Gottingen, Germany
Gottingen, Germany

The University of Göttingen , known informally as Georgia Augusta, is a Public comprehensive research university in the city of Göttingen, Germany. Founded in 1734 by George II, King of Great Britain and Elector of Hanover and starting classes in 1737, the university is the oldest in the state of Lower Saxony, and also the biggest in student enrollment, which stands at around 26,000. The university is highly renowned and respected both in Germany and in the world and has shaped Göttingen into a university city with a high student and faculty population. Wikipedia.

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Riek A.,University of Gottingen | Riek A.,University of New England of Australia | Geiser F.,University of New England of Australia
Biological Reviews | Year: 2013

A large number of analyses have examined how basal metabolic rate (BMR) is affected by body mass in mammals. By contrast, the critical ambient temperatures that define the thermo-neutral zone (TNZ), in which BMR is measured, have received much less attention. We provide the first phylogenetic analyses on scaling of lower and upper critical temperatures and the breadth of the TNZ in 204 mammal species from diverse orders. The phylogenetic signal of thermal variables was strong for all variables analysed. Most allometric relationships between thermal variables and body mass were significant and regressions using phylogenetic analyses fitted the data better than conventional regressions. Allometric exponents for all mammals were 0.19 for the lower critical temperature (expressed as body temperature - lower critical temperature), -0.027 for the upper critical temperature, and 0.17 for the breadth of TNZ. The small exponents for the breadth of the TNZ compared to the large exponents for BMR suggest that BMR per se affects the influence of body mass on TNZ only marginally. However, the breadth of the TNZ is also related to the apparent thermal conductance and it is therefore possible that BMR at different body masses is a function of both the heat exchange in the TNZ and that encountered below and above the TNZ to permit effective homeothermic thermoregulation. © 2013 Cambridge Philosophical Society.

Effendi Y.,Leibniz University of Hanover | Rietz S.,Max Planck Institute for Plant Breeding Research | Fischer U.,University of Gottingen | Scherer G.F.E.,Leibniz University of Hanover
Plant Journal | Year: 2011

Summary AUXIN-BINDING PROTEIN 1 (ABP1) is not easily accessible for molecular studies because the homozygous T-DNA insertion mutant is embryo-lethal. We found that the heterozygous abp1/ABP1 insertion mutant has defects in auxin physiology-related responses: higher root slanting angles, longer hypocotyls, agravitropic roots and hypocotyls, aphototropic hypocotyls, and decreased apical dominance. Heterozygous plants flowered earlier than wild-type plants under short-day conditions. The length of the main root, the lateral root density and the hypocotyl length were little altered in the mutant in response to auxin. Compared to wild-type plants, transcription of early auxin-regulated genes (IAA2, IAA11, IAA13, IAA14, IAA19, IAA20, SAUR9, SAUR15, SAUR23, GH3.5 and ABP1) was less strongly up-regulated in the mutant by 0.1, 1 and 10 μm IAA. Surprisingly, ABP1 was itself an early auxin-up-regulated gene. IAA uptake into the mutant seedlings during auxin treatments was indistinguishable from wild-type. Basipetal auxin transport in young roots was slower in the mutant, indicating a PIN2/EIR1 defect, while acropetal transport was indistinguishable from wild-type. In the eir1 background, three of the early auxin-regulated genes tested (IAA2, IAA13 and ABP1) were more strongly induced by 1 μm IAA in comparison to wild-type, but eight of them were less up-regulated in comparison to wild-type. Similar but not identical disturbances in regulation of early auxin-regulated genes indicate tight functional linkage of ABP1 and auxin transport regulation. We hypothesize that ABP1 is involved in the regulation of polar auxin transport, and thus affects local auxin concentration and early auxin gene regulation. In turn, ABP1 itself is under the transcriptional control of auxin. © 2011 The Authors. The Plant Journal © 2011 Blackwell Publishing Ltd.

Hauck M.,University of Gottingen | Bruyn U.D.,Von Muller Strasse 30 | Leuschner C.,University of Gottingen
Biological Conservation | Year: 2013

Comparing data of epiphytic lichen diversity in semi-natural broad-leaved forests in north-western Germany from the 19th to early 20th centuries with recent inventories revealed strong changes, even though forest structure and tree species composition had changed only little. In three study areas, between 55% and 70% of the species became rarer during the 100-150-year long observation period. In the spatially extended study areas Weser-Ems Lowlands and Solling Mountains, 36% or 39% of the species, respectively, could not be rediscovered in the recent survey. Considering that species might have been overlooked during revisitation, the extinction rate was estimated to be 28% in the Weser-Ems Lowlands and 30% in the Solling Mountains based on a estimated probability for recovering the species of 75% in crustose lichens and 90% in foliose and fruticose lichens. The main causes of the species decline are thought to be forest management (especially the reduction of overmature and decaying trees), the reduction of soil moisture and, with it, air humidity due to drainage as well as the deposition of acidifying and fertilizing substances from the atmosphere. Lichens specialized on rain-sheltered bark furrows and cavities of old trees or smooth, shady bark or moist thick-stemmed deadwood in the forest interior have suffered the strongest declines, including the epiphyte flora of Fagus sylvatica, Central Europe's most abundant native forest tree species. Only few lichens which benefit from nitrogen deposition, global warming or the acidification of bark due to sulphur dioxide pollution have spread. © 2012 Elsevier Ltd.

Skoruppa K.,University of Essex | Mani N.,University of Gottingen | Peperkamp S.,Laboratoire Of Science Cognitives Et Psycholinguistique
Child Development | Year: 2013

Using a picture pointing task, this study examines toddlers' processing of phonological alternations that trigger sound changes in connected speech. Three experiments investigate whether 2;5- to 3-year-old children take into account assimilations-processes by which phonological features of one sound spread to adjacent sounds-for the purpose of word recognition (e.g., in English, ten pounds can be produced as te[mp]ounds). English toddlers (n=18) show sensitivity to native place assimilations during lexical access in Experiment 1. Likewise, French toddlers (n=27) compensate for French voicing assimilations in Experiment 2. However, French toddlers (n=27) do not take into account a hypothetical non-native place assimilation rule in Experiment 3, suggesting that compensation for assimilation is already language specific. © 2012 Society for Research in Child Development, Inc.

Moser T.,University of Gottingen
Physiology | Year: 2012

The organ of Corti, the sensory epithelium of the mammalian auditory system, uses afferent and efferent synapses for encoding auditory signals and topdown modulation of cochlear function. During development, the final precisely ordered sensorineural circuit is established following excessive formation of afferent and efferent synapses and subsequent refinement. Here, we review the development of innervation of the mouse organ of Corti and its regulation. © 2012 Int. Union Physiol. Sci./Am. Physiol. Soc.

Gartner J.,University of Gottingen
Biochimica et Biophysica Acta - Molecular Basis of Disease | Year: 2012

Peroxisomal disorders are an important group of neurometabolic diseases. The clinical presentation is varied in terms of age of onset, severity, and different neurological symptoms. The clinical course spans from death in infancy, rapid functional decline, slow decline on long-term followup, to apparent stable course. Leukoencephalopathy and developmental anomalies are characteristic findings on cerebral MR imaging. From a diagnostic point of view the disorders can be clinically subdivided into four broad categories: (1) the Zellweger spectrum disorders and the peroxisomal ß-oxidation disorders, (2) the rhizomelic chondrodysplasia punctata spectrum disorders, (3) the X-linked adrenoleukodystrophy/adrenomyeloneuropathy complex and (4) the remaining disorders. This article discusses the role of MRI findings in the clinical approach of peroxisomal disorders with neurological disease. This article is part of a Special Issue entitled: Metabolic Functions and Biogenesis of peroxisomes in Health and Disease. © 2012 Elsevier B.V..

Oliveira A.S.,University of Aalborg | Gizzi L.,University Hospital Gdttingen | Farina D.,University of Gottingen | Kersting U.G.,University of Aalborg
Frontiers in Human Neuroscience | Year: 2014

Locomotion can be investigated by factorization of electromyographic (EMG) signals, e.g., with non-negative matrix factorization (NMF). This approach is a convenient concise representation of muscle activities as distributed in motor modules, activated in specific gait phases. For applying NMF, the EMG signals are analyzed either as single trials, or as averaged EMG, or as concatenated EMG (data structure). The aim of this study is to investigate the influence of the data structure on the extracted motor modules. Twelve healthy men walked at their preferred speed on a treadmill while surface EMG signals were recorded for 60s from 10 lower limb muscles. Motor modules representing relative weightings of synergistic muscle activations were extracted by NMF from 40 step cycles separately (EMGSNG), from averaging 2, 3, 5, 10, 20, and 40 consecutive cycles (EMGAVR), and from the concatenation of the same sets of consecutive cycles (EMGCNC). Five motor modules were sufficient to reconstruct the original EMG datasets (reconstruction quality >90%), regardless of the type of data structure used. However, EMGCNC was associated with a slightly reduced reconstruction quality with respect to EMGAVR. Most motor modules were similar when extracted from different data structures (similarity >0.85). However, the quality of the reconstructed 40-step EMGCNC datasets when using the muscle weightings from EMGAVR was low (reconstruction quality ~40%). On the other hand, the use of weightings from EMGCNC for reconstructing this long period of locomotion provided higher quality, especially using 20 concatenated steps (reconstruction quality ~80%). Although EMGSNG and EMGAVR showed a higher reconstruction quality for short signal intervals, these data structures did not account for step-to-step variability. The results of this study provide practical guidelines on the methodological aspects of synergistic muscle activation extraction from EMG during locomotion. © 2014 Oliveira, Gizzi, Farina and Kersting.

Negro F.,University of Aalborg | Negro F.,University of Gottingen | Farina D.,University of Gottingen
Journal of Neurophysiology | Year: 2011

Oscillations in the primary motor cortex are transmitted through the corticospinal tract to the motoneuron pool. This pathway is believed to produce an effective and direct command from the motor cortex to the spinal motoneurons for the modulation of the force output. In this study, we used a computational model of a population of motoneurons to investigate the factors that can influence the transmission of the cortical input to the output of motoneurons, since it can be quantified by coherence analysis. The simulations demonstrated that, despite the nonlinearity of the motoneurons, oscillations present in the cortical input are transmitted to the output of the motoneuron pool at the same frequency. However, the interference introduced by the nonlinearity of the system increases the variability of the oscillations in output, introducing spectral lines whose frequency depends on the input frequencies and the motoneuron discharge rates. Moreover, an additional source of synaptic input common to all motoneurons but independent from the corticospinal component decorrelates the cortical input and motoneuron output and, thus, decreases the magnitude of the estimated coherence, even if the effective cortical drive does not change. These results indicate that the corticospinal input can effectively be sampled by a small population of motoneurons. However, the transmission of a corticospinal drive to the motoneuron pool is influenced by the nonlinearity of the spiking processes of the active motoneurons and by synaptic inputs common to the motoneuron population but independent from the cortical input. © 2011 the American Physiological Society.

Risselada H.J.,Max Planck Institute for Biophysical Chemistry | Marrink S.J.,University of Groningen | Muller M.,University of Gottingen
Physical Review Letters | Year: 2011

Using a coarse-grained molecular model we study the spatial distribution of lipid domains on a 20-nm-sized vesicle. The lipid mixture laterally phase separates into a raftlike, liquid-ordered (lo) phase and a liquid-disordered phase. As we uniaxially compress the mixed vesicle keeping the enclosed volume constant, we impart tension onto the membrane. The vesicle adopts a barrel shape, which is composed of two flat contact zones and a curved edge. The lo domain, which exhibits a higher bending rigidity, segregates to the highly curved edge. This inverted domain sorting switches to normal domain sorting, where the lo domain prefers the flat contact zone, when we release the contents of the vesicle. We rationalize this domain sorting by a pronounced reduction of the bending rigidity and area compressibility of the lo phase upon bending. © 2011 American Physical Society.

Wanger T.C.,University of Adelaide | Wanger T.C.,University of Gottingen
Conservation Letters | Year: 2011

The demand for Lithium-ion batteries as a major power source in portable electronic devices and vehicles is rapidly increasing. I use cumulative data of vehicle, mobile phone, laptop, and digital camera production to show that demand will overshoot the available global Lithium resources before 2025. Even if 100% of all Lithium-ion batteries were recycled today, recycling could not prevent this resource depletion in time. As the increasing Lithium scarcity will increase the price, it will be feasible to mine diluted resources with a strong environmental impact. I highlight these impacts in Lithium-rich Bolivia, the potential new "Saudi Arabia of Lithium." Lithium extraction is likely to cause substantial water pollution, and-through impacts on native diversity-facilitate human health impacts from cyanobacteria that are normally kept at bay by native flamingos. The strongly intertwined Lithium extraction impacts on the environment, biodiversity, and human health from evaporative ponds and ore mining need to be taken into consideration when we discuss resource protection and opportunities from Lithium recycling. Overall, sensible Lithium recycling strategies can provide effective resource and environmental protection right now but urgently need to be supplemented by alternative technologies in the near-future. © 2011 Wiley Periodicals, Inc.

Weigelt P.,University of Gottingen | Steinbauer M.J.,University of Aarhus | Steinbauer M.J.,University of Bayreuth | Cabral J.S.,University of Gottingen | Kreft H.,University of Gottingen
Nature | Year: 2016

Island biogeographical models consider islands either as geologically static with biodiversity resulting from ecologically neutral immigration-extinction dynamics, or as geologically dynamic with biodiversity resulting from immigration-speciation-extinction dynamics influenced by changes in island characteristics over millions of years. Present climate and spatial arrangement of islands, however, are rather exceptional compared to most of the Late Quaternary, which is characterized by recurrent cooler and drier glacial periods. These climatic oscillations over short geological timescales strongly affected sea levels and caused massive changes in island area, isolation and connectivity, orders of magnitude faster than the geological processes of island formation, subsidence and erosion considered in island theory. Consequences of these oscillations for present biodiversity remain unassessed. Here we analyse the effects of present and Last Glacial Maximum (LGM) island area, isolation, elevation and climate on key components of angiosperm diversity on islands worldwide. We find that post-LGM changes in island characteristics, especially in area, have left a strong imprint on present diversity of endemic species. Specifically, the number and proportion of endemic species today is significantly higher on islands that were larger during the LGM. Native species richness, in turn, is mostly determined by present island characteristics. We conclude that an appreciation of Late Quaternary environmental change is essential to understand patterns of island endemism and its underlying evolutionary dynamics.

Behling H.,University of Gottingen | Safford H.D.,University of California at Davis
Global Change Biology | Year: 2010

We present a high-resolution pollen and charcoal record of a 218 cm long sediment core from the Serra dos Órgãos, a subrange of the coastal Serra do Mar, located at 2130 m altitude in campos de altitude (high elevation grass- and shrubland) vegetation near Rio de Janeiro in southeastern Brazil to reconstruct past vegetation, climate and fire dynamics. Based on seven AMS 14C ages, the record represents at least the last 10 450 14C yr bp (12 380 cal years bp), The uppermost region was naturally covered by campos de altitude throughout the recorded period. Diverse montane Atlantic rain forest (ARF) occurred close to the studied peat bog at the end of the Late-glacial period. There is evidence of small Araucaria angustifolia populations in the study area as late as the early Holocene, after which point the species apparently became locally extinct. Between 10 380 and 10 170 14C yr bp (12 310-11 810 cal yr bp), the extent of campos de altitude was markedly reduced as montane ARF shifted rapidly upward to higher elevations, reflecting a very wet and warm period (temperatures similar to or warmer than present day) at the end of the Younger Dryas (YD) chronozone. This is in opposition to the broadly documented YD cooling in the northern Hemisphere. Reduced cross-equatorial heat transport and movement of the Intertropical Convergence Zone over northeastern Brazil may explain the YD warming. Markedly extended campos de altitude vegetation indicates dry climatic conditions until about 4910 14C yr bp (5640 cal yr bp). Later, wetter conditions are indicated by reduced high elevation grassland and the extension of ARF into higher elevation. Fire frequency was high during the early Holocene but decreased markedly after about 7020 14C yr bp (7850 cal yr bp). © 2010 Blackwell Publishing Ltd.

Dideriksen J.L.,University of Aalborg | Negro F.,University of Gottingen | Enoka R.M.,University of Colorado at Boulder | Farina D.,University of Gottingen
Journal of Neurophysiology | Year: 2012

Motoneurons receive synaptic inputs from tens of thousands of connections that cause membrane potential to fluctuate continuously (synaptic noise), which introduces variability in discharge times of action potentials. We hypothesized that the influence of synaptic noise on force steadiness during voluntary contractions is limited to low muscle forces. The hypothesis was examined with an analytical description of transduction of motor unit spike trains into muscle force, a computational model of motor unit recruitment and rate coding, and experimental analysis of inter spike interval variability during steady contractions with the abductor digitiminimi muscle. Simulations varied contraction force, level of synaptic noise, size of motor unit population, recruitment range, twitch contraction times, and level of motor unit short-term synchronization. Consistent with the analytical derivations, simulations and experimental data showed that force variability at target forces above a threshold was primarily due to low-frequency oscillations in neural drive, whereas the influence of synaptic noise was almost completely attenuated by two low-pass filters, one related to convolution of motoneuron spike trains with motor unit twitches (temporal summation) and the other attributableto summation of single motor unit forces (spatial summation). The threshold force above which synaptic noise ceased to influence force steadiness depended on recruitment range, size of motor unit population, and muscle contractile properties. This threshold was low (<10% of maximal force) for typical values of these parameters. Results indicate that motor unit recruitment and muscle properties of a typical muscle are tuned to limit the influence of synaptic noise on force steadiness to low forces and that the inability to produce a constant force during stronger contractions is mainly attributable to the common low-frequency oscillations in motoneuron discharge rates. © 2012 the American Physiological Society.

Balcarek P.,University of Gottingen | Jung K.,University of Gottingen | Sturmer K.M.,University of Gottingen
American Journal of Sports Medicine | Year: 2011

Background: A lateralized tibial tubercle may be a relevant anatomic factor in patients with patellar instability and can be used as an indication for a distal realignment procedure. However, parameter values for the tibial tuberosity-trochlear groove (TT-TG) distance in the young patient have not been defined. It also remains to be determined how this parameter contributes to patellar instability in the growing knee joint. Purpose: The purpose of this study was to evaluate the value of the TT-TG distance in patellar instability in the young athlete. Study Design: Case control study; Level of evidence, 3. Methods: Knee magnetic resonance images were collected from 109 patients with lateral patellar instability and from 136 control subjects. Student t test and multiple logistic regression analysis were used to compare the absolute and relative values of the TTTG distance between patients and controls. The relative value was defined as the ratio between the TT-TG distance and the total width of the distal femur. Results: The TT-TG distance (absolute and relative to femur width) differed significantly between patients with patellar dislocation and the control group (both P≤.01). The TT-TG distances were on average 4 mm larger in patients with patellar dislocation; TTTG distance divided by femur width was on average 5% larger in patients with patellar dislocation. Multiple logistic regression analysis confirmed the TT-TG distance as a significant risk factor for patellar dislocation (P = .04), but showed no significant interaction with patient age or femur width (P = .95 and P = .15, respectively). Conclusion: A lateralized tibial tubercle is a relevant anatomic factor in the young athlete and in the adult patient with lateral patellar instability. Its parameter values and its influence on patellar dislocation are independent of patient age and should therefore be evaluated as in adults. © 2011 The Author(s).

Negro F.,University of Gottingen | Negro F.,University of Aalborg | Farina D.,University of Gottingen
PLoS ONE | Year: 2012

Background: Alpha motoneurons receive common synaptic inputs from spinal and supraspinal pathways. As a result, a certain degree of correlation can be observed between motoneuron spike trains during voluntary contractions. This has been studied by using correlation measures in the time and frequency domains. These measures are interpreted as reflecting different types of connectivity in the spinal networks, although the relation between the degree of correlation of the output motoneuron spike trains and of their synaptic inputs is unclear. Methodology/Principal Findings: In this study, we analyze theoretically this relation and we complete this analysis by simulations and experimental data on the abductor digiti minimi muscle. The results demonstrate that correlation measures between motoneuron output spike trains are inherently influenced by the discharge rate and that this influence cannot be compensated by normalization. Because of the influence of discharge rate, frequency domain measures of correlation (coherence) do not identify the full frequency content of the common input signal when computed from pairs of motoneurons. Rather, an increase in sampling rate is needed by using cumulative spike trains of several motoneurons. Moreover, the application of averaging filters to the spike trains influences the magnitude of the estimated correlation levels calculated in the time, but not in the frequency domain (coherence). Conclusions: It is concluded that the analysis of coherence in different frequency bands between cumulative spike trains of a sufficient number of motoneurons provides information on the spectrum of the common synaptic input. Nonetheless, the absolute values of coherent peaks cannot be compared across conditions with different cumulative discharge rates. © 2012 Negro, Farina.

Biswas T.,Loyola University New Orleans | Gerwick E.,University of Gottingen | Koivisto T.,Institute for Theoretical Physics and Spinoza Institute | Koivisto T.,University of Oslo | And 2 more authors.
Physical Review Letters | Year: 2012

We present the most general covariant ghost-free gravitational action in a Minkowski vacuum. Apart from the much studied f(R) models, this includes a large class of nonlocal actions with improved UV behavior, which nevertheless recover Einstein's general relativity in the IR. © 2012 American Physical Society.

Van Borm C.,University of Groningen | Van Borm C.,University of Gottingen | Spaans M.,University of Groningen
Astronomy and Astrophysics | Year: 2013

Context. The seeds of the supermassive black holes with masses of ∼109M· observed already at z ∼ 6 may have formed through the direct collapse of primordial gas in Tvir ≳ 104 K halos, whereby the gas must stay hot (∼104 K) in order to avoid fragmentation. Aims. The interplay between magnetic fields, turbulence, and a UV radiation background during the gravitational collapse of primordial gas in a halo is explored; in particular, the possibilities for avoiding fragmentation are examined. Methods. Using an analytical one-zone model, the evolution of a cloud of primordial gas is followed from its initial cosmic expansion through turnaround, virialization, and collapse up to a density of 107 cm-3. Results. It was found that in halos with no significant turbulence, the critical UV background intensity (J 21crit) for keeping the gas hot is lower by a factor ∼10 for an initial comoving magnetic field B0 ∼ 2 nG than for the zero-field case, and even lower for stronger fields. In turbulent halos, J21crit is found to be a factor ∼10 lower than for the zero-field-zero-turbulence case, and the stronger the turbulence (more massive halo and/or stronger turbulent heating), the lower J21 crit. Conclusions. The reduction in J21crit is particularly important, since it exponentially increases the number of halos exposed to a supercritical radiation background. © 2013 ESO.

Gerber J.,RWTH Aachen | Nau R.,University of Gottingen
Current Opinion in Neurology | Year: 2010

PURPOSE OF REVIEW: This review describes the pathophysiology of cellular and axonal injury in bacterial meningitis. RECENT FINDINGS: Toll-like receptors have been recognized as important mediators for the initiation of the immune response within the central nervous system. Activation of microglial cells by bacterial products through these receptors increases their ability to phagocytose bacteria, but can also lead to destruction of neurons. The cholesterol-binding hemolysin pneumolysin has a direct toxic effect on neuronal cells. Adjuvant therapy with corticosteroids and glycerol improved the outcome of bacterial meningitis in clinical studies. SUMMARY: Brain damage in bacterial meningitis leading to long-term neurologic sequelae and death is caused by several mechanisms. Bacterial invasion and the release of bacterial compounds promote inflammation, invasion of leukocytes and stimulation of microglia. Leukocytes, macrophages and microglia release free radicals, proteases, cytokines and excitatory amino acids, finally leading to energy failure and cell death. Vasculitis, focal ischemia and brain edema subsequent to an increase in cerebrospinal fluid outflow resistance, breakdown of the blood-brain barrier and swelling of necrotic cells cause secondary brain damage. © 2010 Lippincott Williams & Wilkins.

Landguth E.L.,University of Montana | Balkenhol N.,University of Gottingen
Conservation Genetics | Year: 2012

Population differentiation is often quantified using putatively neutral genetic markers. While adaptive (i. e., selection-driven) genetic markers are becoming increasingly popular, they are mostly used for research on evolutionary processes, such as local adaptation or speciation. Here, we use simulations to evaluate the potential of adaptive genetic data for estimating population differentiation under a range of gene flow, population size, and selection scenarios. Our results suggest that reduced migration can lead to more pronounced genetic differentiation in adaptive versus neutral genetic differentiation, provided that a difference in local selection pressures among spatial locations exists (i. e., spatial selection gradients). These results encourage the use of adaptive genetic data for quantifying genetic differentiation, even in studies focusing on contemporary or recent processes, such as habitat loss and fragmentation. Furthermore, our results illustrate that not testing for selection in putatively neutral markers may lead to incorrect inferences about the processes underlying population differentiation. © 2012 Springer Science+Business Media B.V.

Muceli S.,University of Aalborg | Muceli S.,University of Gottingen | Farina D.,University of Gottingen
IEEE Transactions on Neural Systems and Rehabilitation Engineering | Year: 2012

This paper proposes and tests on able-bodied subjects a control strategy that can be practically applied in unilateral transradial amputees for simultaneous and proportional control of multiple degrees-of-freedom (DOFs). We used artificial neural networks to estimate kinematics of the complex wrist/hand from high-density surface electromyography (EMG) signals of the contralateral limb during mirrored bilateral movements in free space. The movements tested involved the concurrent activation of wrist flexion/extension, radial/ulnar deviation, forearm pronation/supination, and hand closing. The accuracy in estimation was in the range 79%-88% (r 2 index) for the four DOFs in six able-bodied subjects. Moreover, the estimation of the pronation/supination angle (wrist rotation) was influenced by the reduction in the number of EMG channels used for the estimation to a greater extent than the other DOFs. In conclusion, the proposed method and set-up provide a viable means for proportional and simultaneous control of multiple DOFs for hand prostheses. © 2012 IEEE.

News Article | August 24, 2016

(Reuters) - Scientists have discovered a planet that appears to be similar to Earth circling the star closest to the sun, potentially a major step in the quest to find out if life exists elsewhere in the universe, research published on Wednesday showed. The relative proximity of the planet, known as Proxima b, gives scientists a better chance to eventually capture an image of it, to help them establish whether it has an atmosphere and water, which is believed to be necessary for life. Future studies may reveal if any atmosphere contains tell-tale chemicals of biological life, such as methane, according to a paper published in this week's issue of the journal Nature. "The key question of our initiative was whether there were potentially life-bearing planets orbiting these stars. We know now there is at least one planet with some characteristics similar to the Earth," said Pete Worden, a former top NASA manager, who was speaking at a European Southern Observatory webcast news conference to announce the find. The planet, located about 4.2 light-years from Earth, or 25 trillion miles (40 trillion km), is the closest of some 3,500 planets that have been discovered beyond the solar system since 1995, according to the paper. "This planetary system is much closer than any other that we know so detailed investigation is easier," astronomer Ansgar Reiners, with the University of Gottingen in Germany, told reporters on a conference call. Astronomers got their first hint of a planet circling the sun's small dim neighbour star in 2013. But they needed additional observations, using more precise instruments, to make a definitive call. An international team of 31 scientists found the planet after careful and repeated measurements of slight shifts in the colour of the light coming from its host star, Proxima Centauri, which is a small, dim star in the Alpha Centauri system. The shifts, which astronomers call "wobbles," are caused by the gravitational tugging of a planet roughly 1.3 times the size of Earth on the parent star. Based on the timing of wobbles, scientists determined that the planet circles its host star in just 11 days, compared to Earth's 365-day orbit around the sun. That puts the planet far closer to its parent star than Earth orbits the sun. However, Proxima Centauri is so much smaller and dimmer than the sun that its planet's orbit is suitably positioned for liquid water despite being just 4.4 million miles away. "Chances are good that it's a viable, Earth-like planet today," said astronomer Pedro Amado, with the Instituto de Astrofísica de Andalucía in Granada, Spain. But scientists are unsure if red dwarf stars like Proxima Centauri are good hosts for life. Planets orbiting close enough to keep water liquid would be blasted with 100 times more high-energy radiation than Earth receives from the sun, though what impact that would have on life is a matter of scientific debate. "We don't think it's a show-stopper," Amado said. Magnetic fields and an atmosphere offer a planet some protection. It is unknown if Proxima b has either. Before the discovery of Proxima b, the nearest Earth-like planet to the sun was circling a star known as Wolf 1061, located about 14 light-years away. Proxima b may not be flying solo. "We have some suspicions that there is another signal around the star," Reiners said. More research is needed to determine if there are multiple planets circling Proxima Centauri. The discovery announced on Wednesday is expected to bolster a $100 million project unveiled in April and backed by Russian billionaire Yuri Milner to develop a miniature laser-powered spacecraft that can make the trip to the Alpha Centauri system in about 20 years. "We hope to build a whole system that will send nanocraft to Proxima Centauri and Alpha Centauri within a generation," said Worden, the executive director of Breakthrough Starshot, an initiative that aims to deploy thousands of tiny spacecraft to travel to our nearest neighbouring star system and send back pictures.

News Article | August 24, 2016

(Reuters) - Scientists have discovered a planet that appears to be similar to Earth circling the star closest to the sun, potentially a major step in the quest to find out if life exists elsewhere in the universe, research published on Wednesday showed. The relative proximity of the planet, known as Proxima b, gives scientists a better chance to eventually capture an image of it, to help them establish whether it has an atmosphere and water, which is believed to be necessary for life. Future studies may reveal if any atmosphere contains tell-tale chemicals of biological life, such as methane, according to a paper published in this week's issue of the journal Nature. "The key question of our initiative was whether there were potentially life-bearing planets orbiting these stars. We know now there is at least one planet with some characteristics similar to the Earth," said Pete Worden, a former top NASA manager, who was speaking at a European Southern Observatory webcast news conference to announce the find. The planet, located about 4.2 light-years from Earth, or 25 trillion miles (40 trillion km), is the closest of some 3,500 planets that have been discovered beyond the solar system since 1995, according to the paper. "This planetary system is much closer than any other that we know so detailed investigation is easier," astronomer Ansgar Reiners, with the University of Gottingen in Germany, told reporters on a conference call. Astronomers got their first hint of a planet circling the sun's small dim neighbor star in 2013. But they needed additional observations, using more precise instruments, to make a definitive call. An international team of 31 scientists found the planet after careful and repeated measurements of slight shifts in the color of the light coming from its host star, Proxima Centauri, which is a small, dim star in the Alpha Centauri system. The shifts, which astronomers call "wobbles," are caused by the gravitational tugging of a planet roughly 1.3 times the size of Earth on the parent star. Based on the timing of wobbles, scientists determined that the planet circles its host star in just 11 days, compared to Earth's 365-day orbit around the sun. That puts the planet far closer to its parent star than Earth orbits the sun. However, Proxima Centauri is so much smaller and dimmer than the sun that its planet's orbit is suitably positioned for liquid water despite being just 4.4 million miles away. "Chances are good that it's a viable, Earth-like planet today," said astronomer Pedro Amado, with the Instituto de Astrofísica de Andalucía in Granada, Spain. But scientists are unsure if red dwarf stars like Proxima Centauri are good hosts for life. Planets orbiting close enough to keep water liquid would be blasted with 100 times more high-energy radiation than Earth receives from the sun, though what impact that would have on life is a matter of scientific debate. "We don't think it's a show-stopper," Amado said. Magnetic fields and an atmosphere offer a planet some protection. It is unknown if Proxima b has either. Before the discovery of Proxima b, the nearest Earth-like planet to the sun was circling a star known as Wolf 1061, located about 14 light-years away. Proxima b may not be flying solo. "We have some suspicions that there is another signal around the star," Reiners said. More research is needed to determine if there are multiple planets circling Proxima Centauri. The discovery announced on Wednesday is expected to bolster a $100 million project unveiled in April and backed by Russian billionaire Yuri Milner to develop a miniature laser-powered spacecraft that can make the trip to the Alpha Centauri system in about 20 years. "We hope to build a whole system that will send nanocraft to Proxima Centauri and Alpha Centauri within a generation," said Worden, the executive director of Breakthrough Starshot, an initiative that aims to deploy thousands of tiny spacecraft to travel to our nearest neighboring star system and send back pictures.

News Article | March 7, 2016

When Max Born addressed the South Indian Science Association in November 1935, it was a time of great uncertainty in his life. The Nazi Party had already suspended the renowned quantum mechanics physicist's position at the University of Gottingen in 1933. He had been invited to teach at Cambridge, but it was temporary. Then, the Party terminated his tenure at Gottingen in the summer of 1935. Born took up an offer to work with C. V. Raman and his students for six months at the Indian Institute of Science in Bangalore. While there, he found that his family had lost its German citizenship rights. He was stateless and without a permanent home. And then, there was this uncertainty about two numbers. The scientific world had been coming to terms with two numbers that had emerged after a series of discoveries and theories in the previous four decades. They were unchanging and they had no units. One, the fine structure constant, defined the strength of interactions between fundamental particles and light. It is expressed as 1/137. The other, mu, related the mass of a proton to an electron. Born was after a unifying theory to relate all the fundamental forces of nature. He also wanted a theory that would explain where these constants came from. Something, he said, to “explain the existence of the heavy, and light elementary particles and their definite mass quotient 1840." It might seem a little bizarre that Born worried about a couple of constants. The sciences are full of constants—one defines the speed of light, another quantifies the pull of gravity, and so on. We routinely use these numbers, flipping to dog-eared tables in reference books, and coding them into our software without much thought because, well, they are constants. But the weird thing about such constants is that there is no theory to explain their existence. They are universal and they appear to be unchanging. So is the case with the masses of protons and electrons. But time and time again, they are validated through observation and experiment, not theory. What Born and so many others were after was a unifying theory that would demonstrate that there could only be one unchanging value for a constant. Without this theory, scientists resort to testing limits of a constant. Measuring the constant is a good way to verify that theories using them make sense, that science stands on firm ground. Error from the measurements can be a huge concern. So, instead of validating the masses of protons and electrons, it's useful to measure the ratio of their masses, a number that is free of the burden of units. The search for a unifying theory continued. Two years after Born's lecture, his Cambridge colleague, Paul Dirac, wondered in a Nature paper whether the constants were indeed constant if one were to look at the entire history of the cosmos. Measurements on earth are useful but it is a tiny blue dot in the vast universe. What Dirac asked decades ago is what physicists continue to ask today. Is it a constant everywhere in the universe? Why is it a constant? How constant? The question lingered even as the decades rolled on. “The most exact value at present for the ratio of proton to electron mass is 1836.12 +/-0.05,” wrote Friedrich Lenz in a 1951 Physical Review Letters paper. “It may be of interest to note that this number coincides with 6pi^5=1836.12.” That was the entire paper. Questioning the constant is really not that far fetched an idea: the existing theories don't prevent the constants from having a different value. The universe went through three broad phases – the initial radiation dominated phase soon after the Big Bang, a long matter dominated phase, and then a very long dark energy dominated phase that began six billion years ago. One hypothesis is that the mass ratio might have varied only in transitions between the phases. The actual value of the mass ratio (1836.15267389) is not of as much a concern as the uncertainty around its stature as a constant. And scientists have made incredible progress at tackling this uncertainty number. Later this year, researchers from the Vrije Universiteit in Amsterdam along with collaborators from the University of Amsterdam and the Swinburne University of Technology in Melbourne will publish an overview of their findings in the quarterly journal, Review of Modern Physics (the paper is available on arXiv). The mass ratio, they write, varies less than 0.0005 percent, not enough to call it a change. This is based on telescope observations going as far as 12.4 billion years back in time when the universe was only 10 percent of its current age. The conclusion is both mundane and astonishing. Change is so omnipresent that we don't think twice about how much it is part of our fabric. A human cell might endure a million DNA mutations within a day. Summer's green leaves become fall's orange before crackling as winter's brown under our feet, all within a year. Gases coalesced and gravitated around each other over millions of years, packing into rocks like our water-drenched earth that orbits the sun. But underneath all that change lies one number that connects them all and a number that has remain unchanged as far as we can see in the cosmos. And we don't know why. The mu is like scientific gospel that wills the universe into existence. The history of the cosmos is a good sandbox for measuring drifts in the constant. Since light from the early universe continues to reach earth, radio telescopes are effective tools to study the mass ratio. Ancient light interacts with gases in faraway galaxies and stars before reaching earth. The light arrives at earth with a fingerprint of these gases, which absorb certain frequencies of light. It shows up as absences in the spectrum when reviewing the telescope data. By comparing this fingerprint with lab measurements on the same gas, scientists can deduce the mass ratio variations. The Vrije Universiteit group is one of a handful of teams in the world that has been on the case of the proton-electron mass ratio for over a decade. They have collaborated with scientists from Australia, France, Russia, Switzerland, the U.S., the U.K., India and the Phillipines. They have probed tiny bits of hydrogen, ammonia and methanol hovering billions of years away in space. They have compared signals from the Very Large Telescope in the cold, dry desert of north Chile, from a 100-meter radio telescope in a historic spa town in Germany, and from a 30-meter radio telescope in the Spanish Sierra Nevada. They have even used the Hubble Space Telescope to look at white dwarf stars to see if environments with 10,000 times more gravity than earth would alter the mass ratio. And...nada. 'Null result' is one of the most common phrases in their papers. Which is good. Even a small change of a few percent in the value of the ratio would mean a different universe. A smaller mass ratio could mean a wimpier proton, and possibly a weaker pull for the electrons orbiting the nucleus, leading to different kind of matter. While the world isn't very kind to research that doesn't have anything new to offer, a null result doesn't mean the matter can be put to rest. Therein lies the quandry which makes the VU team's research feel like it is equal parts futile and important. No theory in physics can explain the constant mass ratio, the steadfast shepherd of science. It just is, *shrug*. Of course, the VU team is not alone in the search. As early as 1996, another team at the Ioffe Physical Technical Research Institute in Russia analyzed spectral lines from outer space to gauge variations in the mass ratio. Scientists at Cambridge and at the Swinburne University of Technology have looked for drifts in the fine structure constant. But it is the VU group that has perhaps been occupied with the mass ratio the most. Over more than a decade, this preoccupation has produced one of the most comprehensive and intriguing bodies of work. Year after year, across generations of graduate students and post-docs, they have published a paper that gently picks away at the question from different angles – a more distant spot in the universe, a different gravitational environment, a new tool to measure an old problem. The aim for future searches is to hunt further back in time and in different environments. Larger telescopes like the European Extremely Large Telescope will help in gathering fainter signals from the universe. And despite the vast measurements, many are in a very narrow slice of the sky. By broadening the field of view, scientists can probe data from other parts of the universe. The experimental search for a varying constant will likely continue as long as there is no theory to back its existence. A string of null results and small changes to the constant variability helps plug loopholes. As the authors of the Reviews of Modern Physics paper wrote, “Even incremental improvements setting boundaries on drifting fundamental constants are worthwhile to pursue, given the importance of this endeavor into the nature of physical law: Is it constant or not?” Each piece of cosmic doubt is up for scrutiny, to either be nullified in a future experiment or surface as evidence for the next investigator.

Holobar A.,University of Maribor | Minetto M.A.,University of Turin | Farina D.,University of Gottingen
Journal of Neural Engineering | Year: 2014

Objective. A signal-based metric for assessment of accuracy of motor unit (MU) identification from high-density surface electromyograms (EMG) is introduced. This metric, so-called pulse-to-noise-ratio (PNR), is computationally efficient, does not require any additional experimental costs and can be applied to every MU that is identified by the previously developed convolution kernel compensation technique. Approach. The analytical derivation of the newly introduced metric is provided, along with its extensive experimental validation on both synthetic and experimental surface EMG signals with signal-to-noise ratios ranging from 0 to 20 dB and muscle contraction forces from 5% to 70% of the maximum voluntary contraction. Main results. In all the experimental and simulated signals, the newly introduced metric correlated significantly with both sensitivity and false alarm rate in identification of MU discharges. Practically all the MUs with PNR > 30 dB exhibited sensitivity >90% and false alarm rates <2%. Therefore, a threshold of 30 dB in PNR can be used as a simple method for selecting only reliably decomposed units. Significance. The newly introduced metric is considered a robust and reliable indicator of accuracy of MU identification. The study also shows that high-density surface EMG can be reliably decomposed at contraction forces as high as 70% of the maximum. © 2014 IOP Publishing Ltd.

Farina D.,University of Gottingen | Holobar A.,University of Maribor
Proceedings of the IEEE | Year: 2016

Motor units are the smallest functional units of our movements. The study of their activation provides a window into the mechanisms of neural control of movement in humans. The classic methods for motor unit investigations date to several decades ago. They are based on invasive recordings with selective needle or wire electrodes. Conversely, the noninvasive (surface) EMG has been commonly processed as an interference signal, with the extraction of its global characteristics, e.g., amplitude. These characteristics, however, are only crudely associated to the underlying motor unit activities. In the last decade, methods have been proposed for reliably extracting individual motor unit activities from the interference surface EMG signal. We describe these methods in this review, with a focus on blind source separation (BSS) and techniques used on decomposed EMG signals. For example, from the motor unit discharge timings, information can be extracted regarding the synaptic input received by the corresponding motor neurons. In reviewing these methods, we also provide examples of applications in representative conditions, such as pathological tremor. In conclusion, we provide an overview of processing methods of the surface EMG signal that allow a reliable characterization of individual motor units in vivo in humans. © 1963-2012 IEEE.

Storkey J.,Rothamsted Research | Meyer S.,University of Gottingen | Still K.S.,Plantlife | Leuschner C.,University of Gottingen
Proceedings of the Royal Society B: Biological Sciences | Year: 2012

The impact of crop management and agricultural land use on the threat status of plants adapted to arable habitats was analysed using data from Red Lists of vascular plants assessed by national experts from 29 European countries. There was a positive relationship between national wheat yields and the numbers of rare, threatened or recently extinct arable plant species in each country. Variance in the relative proportions of species in different threat categories was significantly explained using a combination of fertilizer and herbicide use, with a greater percentage of the variance partitioned to fertilizers. Specialist species adapted to individual crops, such as flax, are among the most threatened. These species have declined across Europe in response to a reduction in the area grown for the crops on which they rely. The increased use of agro-chemicals, especially in central and northwestern Europe, has selected against a larger group of species adapted to habitats with intermediate fertility. There is an urgent need to implement successful conservation strategies to arrest the decline of this functionally distinct and increasingly threatened component of the European flora. © 2011 The Royal Society.

Friede T.,University of Gottingen | Parsons N.,University of Warwick | Stallard N.,University of Warwick
Statistics in Medicine | Year: 2012

Growing interest in personalised medicine and targeted therapies is leading to an increase in the importance of subgroup analyses. If it is planned to view treatment comparisons in both a predefined subgroup and the full population as co-primary analyses, it is important that the statistical analysis controls the familywise type I error rate. Spiessens and Debois (Cont. Clin. Trials, 2010, 31, 647-656) recently proposed an approach specific for this setting, which incorporates an assumption about the correlation based on the known sizes of the different groups, and showed that this is more powerful than generic multiple comparisons procedures such as the Bonferroni correction. If recruitment is slow relative to the length of time taken to observe the outcome, it may be efficient to conduct an interim analysis. In this paper, we propose a new method for an adaptive clinical trial with co-primary analyses in a predefined subgroup and the full population based on the conditional error function principle. The methodology is generic in that we assume test statistics can be taken to be normally distributed rather than making any specific distributional assumptions about individual patient data. In a simulation study, we demonstrate that the new method is more powerful than previously suggested analysis strategies. Furthermore, we show how the method can be extended to situations when the selection is not based on the final but on an early outcome. We use a case study in a targeted therapy in oncology to illustrate the use of the proposed methodology with non-normal outcomes. © 2012 John Wiley & Sons, Ltd.

Schmidt J.,University of Gottingen | Dalakas M.C.,National and Kapodistrian University of Athens
Expert Review of Clinical Immunology | Year: 2013

Inclusion body myositis is the most common inflammatory myopathy above the age of 50. It becomes clinically apparent around the fourth decade and leads to a slowly, but relentlessly progressive decline in muscular wasting and weakness. The pathology consists of a complex network of inflammatory and degenerative mechanisms, which lead to an attack of muscle fibers by auto-reactive T cells and possibly antibodies. At the same time, various aberrant proteins accumulate within the muscle fibers, including β-amyloid, tau and α-synuclein. Several key components of proinflammatory cell stress mechanisms such as nitric oxide production and macroautophagic processing contribute to the muscle fiber damage. So far, none of the anti-inflammatory or immunomodulatory treatment efforts have been able to halt the disease progression and help the patients. In this summary, the current concept of the complex disease pathology of IBM is reviewed with a focus on recent findings as well as future treatment perspectives. © 2013 Informa UK Ltd.

Schneider F.D.,University of Gottingen | Schneider F.D.,TU Darmstadt | Scheu S.,University of Gottingen | Brose U.,University of Gottingen
Ecology Letters | Year: 2012

Understanding effects of species loss in complex food webs with multiple trophic levels is complicated by the idiosyncrasy of the predator effects on lower trophic levels: direct and indirect effects intermingle and may increase, decrease or not affect ecosystem functioning. We introduce a reductionist approach explaining a predator's trophic effect only by empirically well-founded body-mass constraints on abundance, diet breadth and feeding strength. We demonstrate that this mechanistic concept successfully explains the positive, negative and neutral net effects of predators on decomposers in a litter microcosm experiment. This approach offers a new perspective on the interplay of complex interactions within food webs and is easily extendable to include phylogenetic and other body-mass independent traits. We anticipate that allometry will substantially improve our understanding of idiosyncratic predator effects in experiments and the consequences of predator loss in natural ecosystems. © 2012 Blackwell Publishing Ltd/CNRS.

Background: and objectives The relevance of contact allergens is subject to constant change due to changing exposures according to consumers' preferences and legal requirements. The objective of this paper is to present trends in contact sensitization from the DKG and IVDK patch test clinics, which have led to changes in the DKG standard series (as of 1.1.2014), as well as the current legal framework which has influenced these trends and the way patch testing is performed. Patients and methods The patients from 56 DKG and IVDK patch test clinics from 2010 (n = 13,117), 2011 (n = 13,320) and 2012 (n = 12,529) were analyzed with regard to frequencies of sensitization (hit list) to contact allergens as well as the location of allergic contact dermatitis. Results: With a sensitization rate of 15 % nickel is still the most frequently recognized contact allergen. An increase can be observed for fragrance mix I (9.1 %), the preservative composition of methylchloroisothiazolinone/methylisothiazolinone (MCI/MI) (4.5 %) and methylisothiazolinone (MI) alone (6.8 %). A decline is present for potassium dichromate from above 6 % (2007) to 3 % (2012) and for bufexamac (currently at 0.6 %). Backgrounds, legal requirements and resulting changes to the DKG standard series are illustrated. Conclusions: The indicated trends demonstrate the relevance of clinical epidemiology and the "sentinel function" of DKG and IVDK with regard to public health and prevention of contact allergies. © 2014 Deutsche Dermatologische Gesellschaft (DDG).

Bruck W.,University of Gottingen | Zamvil S.S.,University of California at San Francisco
Expert Review of Clinical Pharmacology | Year: 2012

Laquinimod is a novel, small, orally administered medication that has demonstrated efficacy in the treatment of multiple sclerosis, a chronic inflammatory demyelinating disease of the CNS. In preclinical testing, laquinimod inhibited the development of both acute and chronic paralysis in the multiple sclerosis model, experimental autoimmune encephalomyelitis. Furthermore, laquinimod reduced inflammation, demyelination and axonal damage in experimental autoimmune encephalomyelitis in mice treated at disease induction or at clinical disease onset. Recent findings from the clinical trials indicate that laquinimod has significant effects in reducing relapse rate and has more pronounced effects in reducing sustained disability progression as well as brain atrophy, with a good safety profile. In conclusion, preclinical studies show that laquinimods unique mechanisms of action, including its immunomodulatory and CNS-protective effects, translate into clinical benefits in relapsing-remitting multiple sclerosis patients. © 2012 Expert Reviews Ltd.

Yu H.B.,University of Gottingen | Samwer K.,University of Gottingen | Wang W.H.,CAS Institute of Physics | Bai H.Y.,CAS Institute of Physics
Nature Communications | Year: 2013

Secondary (also known as Johari-Goldstein or β-) relaxations are an intrinsic feature of supercooled liquids and glasses. They are important in many respects but the underlying mechanisms are not well understood. A long-standing puzzle is why some glasses show β-relaxations as pronounced peaks, whereas others as unobvious excess wings. Here we demonstrate that these different behaviours are related to the fluctuations of chemical interactions by using prototypical systems of metallic glasses. A general rule is summarized: pronounced β-relaxations are associated with systems where all the atomic pairs have large similar negative values of enthalpy of mixing, whereas positive or significant fluctuations in enthalpy of mixing suppress β-relaxations. The emerging physical picture is that strong and comparable interactions among all the constituting atoms maintain string-like atomic configurations for the excitations of β-events and can be considered as the formation of molecule-like metallic glasses. © 2013 Macmillan Publishers Limited. All rights reserved.

Mani N.,University of Gottingen | Huettig F.,Max Planck Institute for Psycholinguistics | Huettig F.,Radboud University Nijmegen
Journal of Experimental Child Psychology | Year: 2014

Despite the efficiency with which language users typically process spoken language, a growing body of research finds substantial individual differences in both the speed and accuracy of spoken language processing potentially attributable to participants' literacy skills. Against this background, the current study took a look at the role of word reading skill in listeners' anticipation of upcoming spoken language input in children at the cusp of learning to read; if reading skills affect predictive language processing, then children at this stage of literacy acquisition should be most susceptible to the effects of reading skills on spoken language processing. We tested 8-year-olds on their prediction of upcoming spoken language input in an eye-tracking task. Although children, like in previous studies to date, were successfully able to anticipate upcoming spoken language input, there was a strong positive correlation between children's word reading skills (but not their pseudo-word reading and meta-phonological awareness or their spoken word recognition skills) and their prediction skills. We suggest that these findings are most compatible with the notion that the process of learning orthographic representations during reading acquisition sharpens pre-existing lexical representations, which in turn also supports anticipation of upcoming spoken words. © 2014 Elsevier Inc.

Deponti M.,University of Gottingen | Kozhushkov S.I.,University of Gottingen | Yufit D.S.,Durham University | Ackermann L.,University of Gottingen
Organic and Biomolecular Chemistry | Year: 2013

The chemical behavior of cyclopropyl-substituted alkynes has been probed using the reaction conditions of ruthenium-catalyzed oxidative C-H/O-H and C-H/N-H bond functionalizations. The oxidative annulations proceeded with complete conservation of all cyclopropane fragments and allowed for the one-step preparation of synthetically useful cyclopropyl-substituted isocoumarins and isoquinolones with high regioselectivities and chemical yields. The connectivities of the key heterocyclic products were unambiguously established by X-ray diffraction analysis. This journal is © The Royal Society of Chemistry.

Yu H.-B.,University of Gottingen | Wang W.-H.,CAS Institute of Physics | Samwer K.,University of Gottingen
Materials Today | Year: 2013

Metallic glasses, combining metallic bonding and disordered atomic structures, are at the cutting edge of metallic materials research. Recent advances in this field have revealed that many key questions in glassy physics are inherently connected to one important relaxation mode: the so-called secondary (β) relaxation. Here, in metallic glasses, we review the features of β relaxations and their relations to other processes and properties. Special emphasis is put on their current roles and future promise in understanding the glass transition phenomenon, mechanical properties and mechanisms of plastic deformation, diffusion, physical aging, as well as the stability and crystallization of metallic glasses. © 2013 Elsevier Ltd.

Vucic-Pestic O.,TU Darmstadt | Ehnes R.B.,University of Gottingen | Rall B.C.,University of Gottingen | Brose U.,University of Gottingen
Global Change Biology | Year: 2011

Predictions on the consequences of the rapidly increasing atmospheric CO2 levels and associated climate warming for population dynamics, ecological community structure and ecosystem functioning depend on mechanistic energetic models of temperature effects on populations and their interactions. However, such mechanistic approaches combining warming effects on metabolic (energy loss of organisms) and feeding rates (energy gain by organisms) remain a key, yet elusive, goal. Aiming to fill this void, we studied the metabolic rates and functional responses of three differently sized, predatory ground beetles on one mobile and one more resident prey species across a temperature gradient (5, 10, 15, 20, 25 and 30°C). Synthesizing metabolic and functional-response theory, we develop novel mechanistic predictions how predator-prey interaction strengths (i.e., functional responses) should respond to warming. Corroborating prior theory, warming caused strong increases in metabolism and decreases in handling time. Consistent with our novel model, we found increases in predator attack rates on a mobile prey, whereas attack rates on a mostly resident prey remained constant across the temperature gradient. Together, these results provide critically important information that environmental warming generally increases the direct short-term per capita interaction strengths between predators and their prey as described by functional-response models. Nevertheless, the several fold stronger increase in metabolism with warming caused decreases in energetic efficiencies (ratio of per capita feeding rate to metabolic rate) for all predator-prey interactions. This implies that warming of natural ecosystems may dampen predator-prey oscillations thus stabilizing their dynamics. The severe long-term implications; however, include predator starvation due to energetic inefficiency despite abundant resources. © 2010 Blackwell Publishing Ltd.

Mani N.,University of Gottingen | Huettig F.,Max Planck Institute for Psycholinguistics | Huettig F.,Radboud University Nijmegen
Journal of Experimental Psychology: Human Perception and Performance | Year: 2012

Are there individual differences in children's prediction of upcoming linguistic input and what do these differences reflect? Using a variant of the preferential looking paradigm (Golinkoff, Hirsh-Pasek, Cauley, & Gordon, 1987), we found that, upon hearing a sentence like, "The boy eats a big cake," 2-year-olds fixate edible objects in a visual scene (a cake) soon after they hear the semantically constraining verb eats and prior to hearing the word cake. Importantly, children's prediction skills were significantly correlated with their productive vocabulary size-skilled producers (i.e., children with large production vocabularies) showed evidence of predicting upcoming linguistic input, while low producers did not. Furthermore, we found that children's prediction ability is tied specifically to their production skills and not to their comprehension skills. Prediction is really a piece of cake, but only for skilled producers. © 2012 American Psychological Association.

Meinhold G.,University of Gottingen | Kostopoulos D.K.,National and Kapodistrian University of Athens
Tectonophysics | Year: 2013

The Circum-Rhodope Belt (CRB) sensu stricto comprises low-grade metamorphosed Triassic and Jurassic sedimentary rocks fringing the high-grade metamorphic rocks of the Serbo-Macedonian and Rhodope massifs in northern Greece. Main outcrops occur in the easternmost part of the Vardar suture zone in the Chalkidiki peninsula (Melissochori Formation; formerly Svoula flysch) and in Thrace (Makri unit and Melia Formation). The tectonostratigraphic relationship between the CRB and the high-grade metamorphics has been the subject of long discussions. Older interpretations maintain that the CRB represents the original Mesozoic stratigraphic cover of the Serbo-Macedonian crystalline basement, whereas later revisions propose the existence of two distinct greenschist-facies Mesozoic metasedimentary units: an eastern unit related to the development of a Jurassic black shale basin north of the Rhodope, and a western unit related to the development of an olistostromic flysch in the Cretaceous. Here we present a critical re-evaluation of the CRB with regard to its age, provenance, and tectonic setting based on novel geochemical and isotopic data.The Makri unit and the Melissochori Formation belong to the CRB proper and were deposited in proximity to Carboniferous-Early Permian igneous basement rocks (Pelagonia / Strandja / Thracia Terrane) in latest Triassic and Jurassic times, as shown by a prominent detrital zircon age population of 350-290. Ma. By contrast, the Melia Formation is unrelated to the CRB and was deposited in a foreland basin in front of a metamorphic nappe pile with Rhodopean affinities in the early Cretaceous, as shown by a prominent detrital zircon age population of 315-285. Ma and xenocrysts of ~. 550. Ma and ~. 450. Ma. Thus, the commonly accepted CRB concepts have to be revisited. All units have been tectonically juxtaposed to their present location during Balkan and Alpine orogenic processes. © 2012 Elsevier B.V.

Physical processes acting on leathery and cohesive microbial mats that grow in tidal flats produce a large variety of mat deformation structures (MDS). Among these processes are strong winds which sweep episodically or continuously wide and protected areas of intertidal-supratidal zones covered with microbial mats. Wind-induced MDS occur when a mat layer covering the intertidal zone is floating or loosely attached to the underlying sedimentary layers. Observed MDS triggered by wind shear in recent intertidal to supratidal flats include: i) tearing and breaking up of mats into fragments and pieces of distinct size and shape, ii) network of folds and crumpled structures related to warping and creeping of soft mats, iii) flipped-over edges along shrinkage cracks and tears, iv) rolled-up mat edges and v) wind-blown mat fragments, scattered over the supratidal zone. The observed structures association forms a succession starting from simple tearing and breaking of a mat by wind forces and subsequent crumpling and folding. With continuous strong wind shear acting upon mat surfaces, most of the flipped-over edges are oriented in the direction of wind and form along tears and crack margins; they may evolve into rolled-up edges forming thick cigar-like bodies including both mat and thin sediment layers ('jelly roll'). Dried and non-biostabilised mat fragments are ripped off, transported landward and scattered over upper supratidal and sabkha zones. Within and intertidal-supratidal profile, the structures display a zonality which is controlled by the cohesive behaviour of mats and water-saturation of both mats and underlying sediment substrate. In the absence of recorded physical sedimentary features within the peritidal deposits, recognition and preservation of similar wind-induced mat deformation structures appear critical for environmental interpretation and indicate aeolian processes and an intertidal to supratidal flat setting, flooded intermittently during spring tide or storm events and periodically during high tide. © 2011 Elsevier B.V.

Heckmann L.,TU Darmstadt | Drossel B.,TU Darmstadt | Brose U.,University of Gottingen | Guill C.,University of Gottingen
Ecology Letters | Year: 2012

Body-size structure of food webs and adaptive foraging of consumers are two of the dominant concepts of our understanding how natural ecosystems maintain their stability and diversity. The interplay of these two processes, however, is a critically important yet unresolved issue. To fill this gap in our knowledge of ecosystem stability, we investigate dynamic random and niche model food webs to evaluate the proportion of persistent species. We show that stronger body-size structures and faster adaptation stabilise these food webs. Body-size structures yield stabilising configurations of interaction strength distributions across food webs, and adaptive foraging emphasises links to resources closer to the base. Moreover, both mechanisms combined have a cumulative effect. Most importantly, unstructured random webs evolve via adaptive foraging into stable size-structured food webs. This offers a mechanistic explanation of how size structure adaptively emerges in complex food webs, thus building a novel bridge between these two important stabilising mechanisms. © 2012 Blackwell Publishing Ltd/CNRS.

Ackermann L.,University of Gottingen | Kozhushkov S.I.,University of Gottingen | Yufit D.S.,Durham University
Chemistry - A European Journal | Year: 2012

Intermolecular hydroarylation reactions of highly strained methylenecyclopropanes 2-phenylmethylenecyclopropane (1), 2,2- diphenylmethylenecyclopropane (2), methylenespiropentane (3), bicyclopropylidene (4), (dicyclopropylmethylene)cyclopropane (5), and benzhydrylidenecyclopropane (6) through C-H bond functionalization of 2-phenylpyridine (7 a) and other arenes with directing groups were studied. The reaction was very sensitive to the substitution on the methylenecyclopropanes. Although these transformations involved (cyclopropylcarbinyl)-metal intermediates, substrates 1 and 4 furnished anti-Markovnikov hydroarylation products with complete conservation of all cyclopropane rings in 11-93 % yield, whereas starting materials 3 and 5 were inert toward hydroarylation. Methylenecyclopropane 6 formed the products of formal hydroarylation reactions of the longest distal C-C bond in the methylenecyclopropane moiety in high yield, and hydrocarbon 2 afforded mixtures of hydroarylated products in low yields with a predominance of compounds that retained the cyclopropane unit. As byproducts, Diels-Alder cycloadducts and self-reorganization products were obtained in several cases from substrates 1-3 and 5. The structures of the most important new products have been unambiguously determined by X-ray diffraction analyses. On the basis of the results of hydroarylation experiments with isotopically labeled 7 a-[D 5], a plausible mechanistic rationale and a catalytic cycle for these unusual ruthenium-catalyzed hydroarylation reactions have been proposed. Arene-tethered ruthenium-phosphane complex 53, either isolated from the reaction mixture or independently prepared, did not show any catalytic activity. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Gerard C.,University Paris - Sud | Wrochna M.,University of Gottingen
Communications in Mathematical Physics | Year: 2014

We give a new construction based on pseudo-differential calculus of quasi-free Hadamard states for Klein-Gordon equations on a class of space-times whose metric is well-behaved at spatial infinity. In particular on this class of space-times, we construct all pure Hadamard states whose two-point function (expressed in terms of Cauchy data on a Cauchy surface) is a matrix of pseudo-differential operators. We also study their covariance under symplectic transformations. As an aside, we give a new construction of Hadamard states on arbitrary globally hyperbolic space-times which is an alternative to the classical construction by Fulling, Narcowich and Wald. © 2013 Springer-Verlag Berlin Heidelberg.

Schneider F.D.,University of Gottingen | Schneider F.D.,TU Darmstadt | Brose U.,University of Gottingen
Journal of Animal Ecology | Year: 2013

Summary: The global decline in biodiversity is especially evident in higher trophic levels as predators display higher sensitivity to environmental change than organisms from lower trophic levels. This is even more alarming given the paucity of knowledge about the role of individual predator species in sustaining ecosystem functioning. The effect of predator diversity on lower trophic level prey is often driven by the increasing chance of including the most influential species. Furthermore, intraguild predation can cause trophic cascades with net positive effects on basal prey. As a consequence, the effects of losing a predator species appear to be idiosyncratic and it becomes unpredictable how the community's net effect on lower trophic levels changes when species number is declining. We performed a full factorial microcosm experiment with litter layer arthropods to measure the effects of predator diversity and context-dependent identity effects on a detritivore population and microbial biomass. We show that major parts of the observed diversity effect can be assigned to the increasing likelihood of including the most influential predator. Further, the presence of a second predator feeding on the first predator dampens this dominant effect. Including this intraguild predator on top of the first predator is more likely with increasing predator diversity as well. Thus, the overall pattern can be explained by a second identity effect, which is nested into the first. When losing a predator from the community, the response of the lower trophic level is highly dependent on the remaining predator species. We mechanistically explain the net effects of the predator community on lower trophic levels by nested effects of predator identities. These identity effects become predictable when taking the species' body masses into account. This provides a new mechanistic perspective describing ecosystem functioning as a consequence of species composition and yields an understanding beyond simple effects of biodiversity. Predator species richness affects the lower trophic level. In a full factorial microcosm experiment the authors decomposed the interactive effects of three arthropod predators on a basal springtail population by linear modelling. Nested effects of two predators explain the level of springtail density and microbial biomass. © 2012 The Authors. Journal of Animal Ecology © 2012 British Ecological Society.

Sag C.M.,King's College London | Sag C.M.,University of Gottingen | Wagner S.,University of Gottingen | Maier L.S.,University of Gottingen
Free Radical Biology and Medicine | Year: 2013

In this review article we give an overview of current knowledge with respect to redox-sensitive alterations in Na+ and Ca2+ handling in the heart. In particular, we focus on redox-activated protein kinases including cAMP-dependent protein kinase A (PKA), protein kinase C (PKC), and Ca/calmodulin-dependent protein kinase II (CaMKII), as well as on redox-regulated downstream targets such as Na+ and Ca2+ transporters and channels. We highlight the pathological and physiological relevance of reactive oxygen species and some of its sources (such as NADPH oxidases, NOXes) for excitation - contraction coupling (ECC). A short outlook with respect to the clinical relevance of redox-dependent Na+ and Ca2+ imbalance will be given. © 2013 Elsevier Inc. All rights reserved.

Arcadi G.,University of Gottingen | Mambrini Y.,University Paris - Sud | Tytgat M.H.G.,Free University of Colombia | Zaldivar B.,Free University of Colombia
Journal of High Energy Physics | Year: 2014

We consider a simple, yet generic scenario in which a new heavy Z' gauge boson couples both to SM fermions and to dark matter. In this framework we confront the best LHC limits on an extra gauge boson Z' to the constraints on couplings to dark matter from direct detection experiments. In particular we show that the LHC searches for resonant production of dileptons and the recent exclusion limits obtained by the LUX collaboration give complementary constraints. Together, they impose strong bounds on the invisible branching ratio and exclude a large part of the parameter space for generic Z' models. Our study encompasses many possible Z' models, including SSM, E6- inspired or B-L scenario. © The Authors.

Pfluger-Grau K.,CSIC - National Center for Biotechnology | Gorke B.,University of Gottingen
Trends in Microbiology | Year: 2010

In addition to the sugar phosphotransferase system (sugar PTS) dedicated to carbohydrate uptake, many Gram-negative bacteria possess a so-called nitrogen PTS (PTSNtr). Although fulfilling very different functions, both systems can communicate with each other by phosphate exchange. PTSNtr regulates diverse processes implicated in metabolism of nitrogen and carbon, and is essential for virulence in some bacteria. Additionally, it plays a role in potassium homeostasis by regulating the expression and activity of a high- and a low-affinity K+ transporter, respectively. In this article, we review recent advances in the understanding of the regulatory roles of PTSNtr in various organisms. © 2010 Elsevier Ltd.

Hasenfuss G.,University of Gottingen | Teerlink J.R.,University of California at San Francisco | Teerlink J.R.,Veterans Affairs Medical Center
European Heart Journal | Year: 2011

Intrinsic inotropic stimulation of the heart is central to the regulation of cardiovascular function, and exogenous inotropic therapies have been used clinically for decades. Unfortunately, current inotropic drugs have consistently failed to show beneficial effects beyond short-term haemodynamic improvement in patients with heart failure. To address these limitations, new agents targeting novel mechanisms are being developed: (i) istaroxime has been developed as a non-glycoside inhibitor of the sodium-potassium-ATPase with additional stimulatory effects on the sarcoplasmic reticulum calcium pump (SERCA) and has shown lusitropic and inotropic properties in experimental and early clinical studies; (ii) from a mechanistic point of view, the cardiac myosin activators, directly activating the acto-myosin cross-bridges, are most appealing with improved cardiac performance in both animal and early clinical studies; (iii) gene therapy approaches have been successfully employed to increase myocardial SERCA2a; (iv) nitroxyl donors have been developed and have shown evidence of positive lusitropic and inotropic, as well as potent vasodilatory effects in early animal studies; (v) the ryanodine receptor stabilizers reduce pathological leak of calcium from the sarcoplasmic reticulum with initial promising pre-clinical results; and finally, (vi) metabolic energy modulation may represent a promising means to improve contractile performance of the heart. There is an urgent clinical need for agents that improve cardiac performance with a favourable safety profile. These current novel approaches to improving cardiac function provide the hope that such agents may soon be available. © 2011 The Author.

Yu H.B.,University of Gottingen | Samwer K.,University of Gottingen | Wu Y.,University of North Carolina at Chapel Hill | Wang W.H.,CAS Institute of Physics
Physical Review Letters | Year: 2012

In multicomponent metallic glasses, we demonstrate that diffusion and secondary (β) relaxation are closely related. The diffusion motion of the smallest constituting atoms takes place within the temperature and time regimes where the β relaxations are activated, and, in particular, the two processes have similar activation energies. We suggest cooperative stringlike atomic motion plays an important role in both processes. This finding provides additional insights into the structural origin of the β relaxations as well as the mechanisms of diffusions in metallic glasses. © 2012 American Physical Society.

Wesche K.,Senckenberg Museum of Natural History Gorlitz | Krause B.,University of Gottingen | Culmsee H.,Heritage Foundation | Leuschner C.,University of Gottingen
Biological Conservation | Year: 2012

There is growing concern that biodiversity loss in European agricultural landscapes is having negative effects on functional trait diversity. Long-term studies examining vegetation changes from the period before agricultural industrialisation are however rare. Here, we ask how management intensification and increased nutrient input initiated in the 1950/1960s have altered grassland plant community composition, species diversity and functional trait composition using comprehensive datasets from five floodplain regions (plus one protected reference region) in northern Germany. Sites with available historical relevés and vegetation maps (1950/1960s, 1990s) were resampled in 2008 to facilitate the analysis of a period spanning four to five decades.Plant community composition changed tremendously in all study regions during the 50. year period, which was related to increasing Ellenberg indicator values for nutrient availability. Species richness at the plot-level fell by 30-50% over the period, and losses in functional diversity were equally large. A non-formal comparison with the results from the protected reference study region indicates that the changes may mostly be attributable to local nutrient input rather than to supra-regional climate change. Our results indicate a consistent trend towards much more species-poor communities dominated by mow-tolerant, N-demanding competitive grasses, whereas species with more ruderal strategies, species flowering early in the season and, in particular, insect-pollinated herbs have all decreased. The substantial loss of nectar-producing grassland herbs is likely to have negative effects on the abundance of pollinating insects, with consequences for the grassland animal communities. This highlights the growing need for adequate grassland management schemes with low N input to preserve high-nature-value grassland. © 2012 Elsevier Ltd.

Aggarwal S.,Max Planck Institute for Experimental Medicine | Yurlova L.,Max Planck Institute for Experimental Medicine | Simons M.,Max Planck Institute for Experimental Medicine | Simons M.,University of Gottingen
Trends in Cell Biology | Year: 2011

The wrapping of multiple layers of myelin membrane sheets around an axon is of fundamental importance for the function of the nervous system. In the central nervous system (CNS) oligodendrocytes synthesize tremendous amounts of cellular membrane to form multiple myelin internodes of highly stable membranes with a specific set of tightly packed lipids and proteins. In recent years, mouse mutants have allowed great advances in our understanding of the functional and structural role of many of the major components of myelin. The challenge now is to extend this knowledge to unravel the molecular machinery and mechanisms required to synthesize, assemble and wrap myelin multiple times around an axon at the appropriate developmental time. Such insight will be essential in designing new therapeutic strategies to promote remyelination in demyelinating disorders such as multiple sclerosis. © 2011 Elsevier Ltd.

Sloan K.E.,Newcastle University | Sloan K.E.,University of Gottingen | Bohnsack M.T.,University of Gottingen | Schneider C.,Newcastle University | Watkins N.J.,Newcastle University
RNA | Year: 2014

During eukaryotic ribosome biogenesis, three of the mature ribosomal (r)RNAs are released from a single precursor transcript (pre-rRNA) by an ordered series of endonucleolytic cleavages and exonucleolytic processing steps. Production of the 18S rRNA requires the removal of the 5' external transcribed spacer (5'ETS) by endonucleolytic cleavages at sites A0 and A1/site 1. In metazoans, an additional cleavage in the 5'ETS, at site A', upstream of A0, has also been reported. Here, we have investigated how A' processing is coordinated with assembly of the early preribosomal complex. We find that only the tUTP (UTP-A) complex is critical for A' cleavage, while components of the bUTP (UTP-B) and U3 snoRNP are important, but not essential, for efficient processing at this site. All other factors involved in the early stages of 18S rRNA processing that were tested here function downstream from this processing step. Interestingly, we show that the RNA surveillance factors XRN2 and MTR4 are also involved in A' cleavage in humans. A' cleavage is largely bypassed when XRN2 is depleted, and we also discover that A' cleavage is not always the initial processing event in all cell types. Together, our data suggest that A' cleavage is not a prerequisite for downstream pre-rRNA processing steps and may, in fact, represent a quality control step for initial pre-rRNA transcripts. Furthermore, we show that components of the RNA surveillance machinery, including the exosome and TRAMP complexes, also play key roles in the recycling of excised spacer fragments and degradation of aberrant pre-rRNAs in human cells. © 2014 Jambor et al.

Neesse A.,University of Gottingen | Algul H.,TU Munich | Tuveson D.A.,Pancreatic Cancer Research Laboratory | Gress T.M.,University of Marburg
Gut | Year: 2015

Pancreatic ductal adenocarcinoma (PDA) exhibits one of the poorest prognosis of all solid tumours and poses an unsolved problem in cancer medicine. Despite the recent success of two combination chemotherapies for palliative patients, the modest survival benefits are often traded against significant side effects and a compromised quality of life. Although the molecular events underlying the initiation and progression of PDA have been intensively studied and are increasingly understood, the reasons for the poor therapeutic response are hardly apprehended. One leading hypothesis over the last few years has been that the pronounced tumour microenvironment in PDA not only promotes carcinogenesis and tumour progression but also mediates therapeutic resistance. To this end, targeting of various stromal components and pathways was considered a promising strategy to biochemically and biophysically enhance therapeutic response. However, none of the efforts have yet led to efficacious and approved therapies in patients. Additionally, recent data have shown that tumour-associated fibroblasts may restrain rather than promote tumour growth, reinforcing the need to critically revisit the complexity and complicity of the tumour-stroma with translational implications for future therapy and clinical trial design.

Jerabek P.,University of Marburg | Roesky H.W.,University of Gottingen | Bertrand G.,University of California at San Diego | Frenking G.,University of Marburg
Journal of the American Chemical Society | Year: 2014

Quantum chemical calculations using density functional theory have been carried out for the cyclic (alkyl)(amino)carbene (cAAC) complexes of the group 11 atoms [TM(cAAC)2] (TM = Cu, Ag, Au) and their cations [TM(cAAC)2]+. The nature of the metal-ligand bonding was investigated with the charge and energy decomposition analysis EDA-NOCV. The calculations show that the TM-C bonds in the charged adducts [TM(cAAC)2]+ are significantly longer than in the neutral complexes [TM(cAAC)2], but the cations have much higher bond dissociation energies than the neutral molecules. The intrinsic interaction energies δEint in [TM(cAAC)2]+ take place between TM+ in the 1S electronic ground state and (cAAC)2. In contrast, the metal-ligand interactions in [TM(cAAC)2] involve the TM atoms in the excited 1P state yielding strong TM p(π) → (cAAC)2 π backdonation, which is absent in the cations. The calculations suggest that the cAAC ligands in [TM(cAAC)2] are stronger π acceptors than σ donors. The trends of the intrinsic interaction energies and the bond dissociation energies of the metal-ligand bonds in [TM(cAAC)2] and [TM(cAAC)2]+ give the order Au > Cu > Ag. Calculations at the nonrelativistic level give weaker TM-C bonds, particularly for the gold complexes. The trend for the bond strength in the neutral and charged adducts without relativistic effects becomes Cu > Ag > Au. The EDA-NOCV calculations suggest that the weaker bonds at the nonrelativistic level are mainly due to stronger Pauli repulsion and weaker orbital interactions. The NBO picture of the C-TM-C bonding situation does not correctly represent the nature of the metal-ligand interactions in [TM(cAAC)2]. © 2014 American Chemical Society.

Guerdane M.,Karlsruhe Institute of Technology | Teichler H.,University of Gottingen | Nestler B.,Karlsruhe Institute of Technology
Physical Review Letters | Year: 2013

We illustrate for a solid-liquid interface how local atomic order in a metallic melt (NiZr) transforms into a massive in-plane ordering at the surface of a crystal (bcc Zr) when commensurability is given between the solute-centered clusters of the melt and the periodic potential of the crystalline surface for a given orientation. Linking molecular dynamics simulation to phase-field modeling allows us to estimate quantitatively the influence of the surface effect on the growth kinetics. This study sheds new light on the relation between the undercooling ability (e.g., in the case of glass-forming alloys) and the pronounced local order in the melt. © 2013 American Physical Society.

Bunermann O.,University of Gottingen | Stienkemeier F.,Albert Ludwigs University of Freiburg
European Physical Journal D | Year: 2011

The doping process of helium nanodroplets with alkali atoms has been modeled in order to study deviations from the Poissonian statistics of measured pick-up statistics which are important for assigning cluster or complex sizes in many experimental studies. Several, formally unexplained findings are reproduced and their origin has been analyzed: derivations from the expected functional form of the initial incline, the suppression of the formation of lithium clusters, the influence of the functional form and width of droplet size distributions. Furthermore, the controversially discussed formation of high-spin alkali clusters on helium droplets has been calculated within the model. The selection of high-spin states comes out to depend strongly on the experimental conditions, and is in general not pronounced for cluster sizes 3. The enhancement factor of 50 of high-spin states reported in earlier experiments is reproduced when choosing the conditions of these experiments. © 2011 EDP Sciences, SIF, Springer-Verlag Berlin Heidelberg.

Culmsee H.,University of Gottingen | Culmsee H.,Heritage Foundation | Leuschner C.,University of Gottingen
Journal of Biogeography | Year: 2013

Aim: In order to investigate the relative importance of ecological (habitat specialization) and biogeographical (speciation, geographical dispersal limitation) processes as causes of non-random spatial distribution of tree species in the mountain forests of Malesia, we analysed the elevational change in the taxonomic and phylogenetic diversity of tree assemblages in different biogeographical subregions. Location: Malesia (Borneo, Java, Sulawesi and the Philippines). Methods: Tree inventory data of 12 old-growth forests from a wide elevational range (650-3080 m a.s.l.) were taxonomically harmonized and standardized (50 random draws of 245 individuals each per plot), and the phylogeny of 204 genera was resolved and scaled to its evolutionary origin. The taxonomic and phylogenetic diversities were calculated using effective generic measures, and the diversity patterns analysed by regression, ordination and classification. Results: The primary factor determining the diversity patterns of the tree assemblages was elevation, whereas the influence of region was surprisingly low. This results in common elevational patterns in taxonomic and phylogenetic community structure across western and central Malesia. The major clades of the contemporary mountain forest trees must therefore have evolved before the formation of the Malay Archipelago in its present form (sympatric speciation). Taxonomic richness and phylogenetic diversity exhibited opposite trends with elevation. Generic richness decreased linearly with elevation; the phylogenetic structure of high-elevation forests revealed overdispersion, indicating convergent trait evolution towards higher elevations, whereas the submontane and colline assemblages showed clustering with a considerable number of confamilials. The upper montane forests of Borneo and Sulawesi were characterized by the dominance of Southern Hemisphere conifers, which differentiated them from lower-elevation communities. Main conclusions: Our results indicate that ecological, evolutionary and biogeographical processes (environmental filtering, sympatry and long-distance dispersal) have shaped the contemporary community structure of Malesian mountain forests. Wallace's Line may represent a significant barrier between the lowland tree floras of Borneo and Sulawesi, but this is not true for those at higher elevations. The uniqueness of high-elevation forests in terms of their high phylogenetic diversity and of their unusual structure calls for a high priority in conservation programmes. © 2013 John Wiley & Sons Ltd.

Nielsen A.B.,University of Gottingen | Odgaard B.V.,University of Aarhus
Vegetation History and Archaeobotany | Year: 2010

This paper explores the spatial and temporal land-cover variability within the main cultural landscape units in Denmark during the last 3,000 years. Quantitative estimates of the cover of trees, grasses, Cerealia and Calluna around nine Danish lakes were obtained using the recently developed Landscape Reconstruction Algorithm (LRA) (Sugita 2007a, b). The performance of the approach was evaluated by comparing reconstructed vegetation based on A.D. 1800 pollen spectra to land cover from historical maps of the same period. Although the model tended to overestimate grassland cover by 10-20%, the reconstructed vegetation was much more similar to the observed than the uncorrected pollen proportions. The LRA was then applied to 3,000 year long pollen records to reconstruct the vegetation development around each of the nine sites. The results support earlier conclusions regarding the relative stability of woodland, agrarian and heathland dominated landscapes in Denmark (Odgaard and Rasmussen 2000), with the distribution of the main landscape types determined by topography and soil characteristics. The present study indicates that the transition zones between agricultural and forest dominated landscapes were the most dynamic, acting as buffer zones where most of the expansions and contractions of agricultural activities took place. The quantitative vegetation reconstructions underline the importance of farming and especially pastoral activities in shaping the Danish landscapes throughout the study period. © 2010 The Author(s).

Kaufmann D.,Karlsruhe Institute of Technology | Monig R.,Karlsruhe Institute of Technology | Volkert C.A.,University of Gottingen | Kraft O.,Karlsruhe Institute of Technology
International Journal of Plasticity | Year: 2011

The size dependence of deformation of Ta was studied using compression tests of focused ion beam (FIB) machined microcolumns. Columns with diameters between 0.5 and 8 μm with 〈1 1 1〉 and 〈1 0 0〉 orientations along the column axis were tested. By comparing results of bcc Ta columns with results from previous experiments on fcc metals it was found that Ta shows significantly higher normalized yield stresses in combination with a weaker sample size dependence. The differences between bcc and fcc metals can be attributed to the different dislocation behaviour of bcc metals, especially to the lower mobility of screw dislocations. © 2010 Elsevier Ltd. All rights reserved.

Sowa H.,University of Gottingen | Fischer W.,University of Marburg
Acta Crystallographica Section A: Foundations of Crystallography | Year: 2010

All homogeneous sphere packings and all interpenetrating layers of spheres were derived that refer to the 18 orthorhombic trivariant lattice complexes with mirror symmetry. In total, sphere packings of 51 different types have been found. Only for 28 of these types is the maximal inherent symmetry of their sphere packings orthorhombic. Some crystal structures that can be described by means of sphere packings are listed. © 2010 International Union of Crystallography. Printed in Singapore-all rights reserved.

de Hoz L.,Max Planck Institute for Experimental Medicine | Simons M.,Max Planck Institute for Experimental Medicine | Simons M.,University of Gottingen
BioEssays | Year: 2015

Myelin is required for efficient nerve conduction, but not all axons are myelinated to the same extent. Here we review recent studies that have revealed distinct myelination patterns of different axonal paths, suggesting that myelination is not an all or none phenomenon and that its presence is finely regulated in central nervous system networks. Whereas powerful reductionist biology has led to important knowledge of how oligodendrocytes function by themselves, little is known about their role in neuronal networks. We still do not understand how oligodendrocytes integrate information from neurons to adapt their function to the need of the system. An intricate cross talk between neurons and glia is likely to exist and to determine how neuronal circuits operate as a whole. Dissecting these mechanisms by using integrative systems biology approaches is one of the major challenges ahead. © 2015 WILEY Periodicals, Inc.

Simons M.,Max Planck Institute for Experimental Medicine | Simons M.,University of Gottingen | Lyons D.A.,University of Edinburgh
Current Opinion in Cell Biology | Year: 2013

The formation of myelin in the central nervous system is a multi-step process that involves coordinated cell-cell interactions and dramatic changes in plasma membrane architecture. First, oligodendrocytes send our numerous highly ramified processes to sample the axonal environment and decide which axon(s) to select for myelination. After this decision is made and individual axon to oligodendrocyte contact has been established, the exploratory process of the oligodendrocyte is converted into a flat sheath that spreads and winds along and around its associated axon to generate a multilayered membrane stack. By compaction of the opposing extracellular layers of membrane and extrusion of almost all cytoplasm from the intracellular domain of the sheath, the characteristic membrane-rich multi-lamellar structure of myelin is formed. Here we highlight recent advances in identifying biophysical and signalling based mechanisms that are involved in axonal selection and myelin sheath generation by oligodendrocytes. A thorough understanding of the mechanisms underlying these events is a prerequisite for the design of novel myelin repair strategies in demyelinating and dysmyelinating diseases. © 2013 Elsevier Ltd.

Zemel A.,Fritz Haber Institute | Rehfeldt F.,University of Pennsylvania | Rehfeldt F.,University of Gottingen | Brown A.E.X.,University of Pennsylvania | And 2 more authors.
Nature Physics | Year: 2010

The shape and differentiated state of many cell types are highly sensitive to the rigidity of the microenvironment. The physical mechanisms involved, however, are unknown. Here, we present a theoretical model and experiments demonstrating that the alignment of stress fibres within stem cells is a non-monotonic function of matrix rigidity. We treat the cell as an active elastic inclusion in a surrounding matrix, allowing the actomyosin forces to polarize in response to elastic stresses developed in the cell. The theory correctly predicts the monotonic increase of the cellular forces with the matrix rigidity and the alignment of stress fibres parallel to the long axis of cells. We show that the anisotropy of this alignment depends non-monotonically on matrix rigidity and demonstrate it experimentally by quantifying the orientational distribution of stress fibres in stem cells. These findings offer physical insight into the sensitivity of stem-cell differentiation to tissue elasticity and, more generally, introduce a cell-type-specific parameter for actomyosin polarizability. © 2010 Macmillan Publishers Limited. All rights reserved.

van der Laan M.,Albert Ludwigs University of Freiburg | Hutu D.P.,University of Gottingen | Rehling P.,University of Gottingen
Biochimica et Biophysica Acta - Molecular Cell Research | Year: 2010

Mitochondria are organelles of endosymbiontic origin that contain more than one thousand different proteins. The vast majority of these proteins is synthesized in the cytosol and imported into one of four mitochondrial subcompartments: outer membrane, intermembrane space, inner membrane and matrix. Several import pathways exist and are committed to different classes of precursor proteins. The presequence translocase of the inner mitochondrial membrane (TIM23 complex) mediates import of precursor proteins with cleavable amino-terminal presequences. Presequences direct precursors across the inner membrane. The combination of this presequence with adjacent regions determines if a precursor is fully translocated into the matrix or laterally sorted into the inner mitochondrial membrane. The membrane-embedded TIM23SORT complex mediates the membrane potential-dependent membrane insertion of precursor proteins with a stop-transfer sequence downstream of the mitochondrial targeting signal. In contrast, translocation of precursor proteins into the matrix requires the recruitment of the presequence translocase-associated motor (PAM) to the TIM23 complex. This ATP-driven import motor consists of mitochondrial Hsp70 and several membrane-associated co-chaperones. These two structurally and functionally distinct forms of the TIM23 complex (TIM23SORT and TIM23MOTOR) are in a dynamic equilibrium with each other. In this review, we discuss recent advances in our understanding of the mechanisms of matrix translocation and membrane insertion by the TIM23 machinery. © 2010 Elsevier B.V.

Muller M.,Laser Laboratorium Gottingen e.V. | Mey T.,Laser Laboratorium Gottingen e.V. | Niemeyer J.,University of Gottingen | Mann K.,Laser Laboratorium Gottingen e.V.
Optics Express | Year: 2014

An extremely compact soft x-ray microscope operating in the "water window" region at the wavelength λ = 2.88 nm is presented, making use of a long-term stable and nearly debris-free laser-induced plasma from a pulsed nitrogen gas jet target. The well characterized soft x-ray radiation is focused by an ellipsoidal grazing incidence condenser mirror. Imaging of a sample onto a CCD camera is achieved with a Fresnel zone plate using magnifications up to 500x. The spatial resolution of the recorded microscopic images is about 100 nm as demonstrated for a Siemens star test pattern. ©2014 Optical Society of America.

Dudek J.,University of Gottingen | Rehling P.,University of Gottingen | Rehling P.,Max Planck Institute for Chemistry | van der Laan M.,Albert Ludwigs University of Freiburg
Biochimica et Biophysica Acta - Molecular Cell Research | Year: 2013

Most mitochondrial proteins are encoded in the nucleus. They are synthesized as precursor forms in the cytosol and must be imported into mitochondria with the help of different protein translocases. Distinct import signals within precursors direct each protein to the mitochondrial surface and subsequently onto specific transport routes to its final destination within these organelles. In this review we highlight common principles of mitochondrial protein import and address different mechanisms of protein integration into mitochondrial membranes. Over the last years it has become clear that mitochondrial protein translocases are not independently operating units, but in fact closely cooperate with each other. We discuss recent studies that indicate how the pathways for mitochondrial protein biogenesis are embedded into a functional network of various other physiological processes, such as energy metabolism, signal transduction, and maintenance of mitochondrial morphology. This article is part of a Special Issue entitled: Protein Import and Quality Control in Mitochondria and Plastids. © 2012 Elsevier B.V.

Stolz A.,University of Gottingen | Stolz A.,University of Marburg | Ertych N.,University of Gottingen | Bastians H.,University of Gottingen
Clinical Cancer Research | Year: 2011

CHK2 is a multiorgan tumor susceptibility gene that encodes for a serine/threonine protein kinase involved in the response to cellular DNA damage. After ATM-mediated phosphorylation, the activated Chk2 kinase can act as a signal transducer and phosphorylate a variety of substrates, including the Cdc25 phosphatases, p53, PML, E2F-1, and Brca1, which has been associated with halting the cell cycle, the initiation of DNA repair, and the induction of apoptosis after DNA damage. In addition, recent work has revealed another, DNA-damage-independent function of Chk2 during mitosis that is required for proper mitotic spindle assembly and maintenance of chromosomal stability. This novel role involves a mitotic phosphorylation of the tumor suppressor Brca1 by the Chk2 kinase. On the basis of its role during DNA damage response, Chk2 has been suggested as an anticancer therapy target, but given its recently discovered new function and its role as a tumor suppressor, it is questionable whether inhibition of Chk2 is indeed beneficial for anticancer treatment. However, investigators may be able to exploit the loss of CHK2 in human tumors to develop novel therapies based on synthetic lethal interactions. ©2010 AACR.

Simons M.,Max Planck Institute for Experimental Medicine | Simons M.,University of Gottingen
Sub-Cellular Biochemistry | Year: 2010

Myelin consists of several layers of tightly compacted membranes wrapped around axons in the nervous system. The main function of myelin is to provide electrical insulation around the axon to ensure the rapid propagation of nerve conduction. As the myelinating glia terminally differentiates, they begin to produce myelin membranes on a remarkable scale. This membrane is unique in its composition being highly enriched in lipids, in particular galactosylceramide and cholesterol. In this review we will summarize the role of cholesterol in myelin biogenesis in the central and peripheral nervous system. © Springer Science+Business Media B.V. 2010.

Rahat M.A.,Immunology Research Unit | Hemmerlein B.,University of Gottingen
Frontiers in Physiology | Year: 2013

Tumor cell-macrophage interactions change as the tumor progresses, and the generation of nitric oxide (NO) by the inducible nitric oxide synthase (iNOS) plays a major role in this interplay. In early stages, macrophages employ their killing mechanisms, particularly the generation of high concentrations of NO and its derivative reactive nitrogen species (RNS) to initiate tumor cell apoptosis and destroy emerging transformed cells. If the tumor escapes the immune system and grows, macrophages that infiltrate it are reprogramed in situ by the tumor microenvironment. Low oxygen tensions (hypoxia) and immunosuppressive cytokines inhibit iNOS activity and lead to production of low amounts of NO/RNS, which are pro-angiogenic and support tumor growth and metastasis by inducing growth factors (e.g., VEGF) and matrix metalloproteinases (MMPs). We review here the different roles of NO/RNS in tumor progression and inhibition, and the mechanisms that regulate iNOS expression and NO production, highlighting the role of different subtypes of macrophages and the microenvironment. We finally claim that some tumor cells may become resistant to macrophage-induced death by increasing their expression of microRNA-146a (miR-146a), which leads to inhibition of iNOS translation. This implies that some cooperation between tumor cells and macrophages is required to induce tumor cell death, and that tumor cells may control their fate. Thus, in order to induce susceptibility of tumors cells to macrophage-induced death, we suggest a new therapeutic approach that couples manipulation of miR-146a levels in tumors with macrophage therapy, which relies on ex vivo stimulation of macrophages and their re-introduction to tumors. © 2013 Rahat and Hemmerlein.

Nagler J.,Max Planck Institute for Dynamics and Self-Organization | Nagler J.,University of Gottingen | Levina A.,Max Planck Institute for Dynamics and Self-Organization | Levina A.,Bernstein Center for Computational Neuroscience Gottingen | And 3 more authors.
Nature Physics | Year: 2011

How a complex network is connected crucially impacts its dynamics and function. Percolation, the transition to extensive connectedness on gradual addition of links, was long believed to be continuous, but recent numerical evidence of 'explosive percolationg' suggests that it might also be discontinuous if links compete for addition. Here we analyse the microscopic mechanisms underlying discontinuous percolation processes and reveal a strong impact of single-link additions. We show that in generic competitive percolation processes, including those showing explosive percolation, single links do not induce a discontinuous gap in the largest cluster size in the thermodynamic limit. Nevertheless, our results highlight that for large finite systems single links may still induce substantial gaps, because gap sizes scale weakly algebraically with system size. Several essentially macroscopic clusters coexist immediately before the transition, announcing discontinuous percolation. These results explain how single links may drastically change macroscopic connectivity in networks where links add competitively. © 2011 Macmillan Publishers Limited. All rights reserved.

Rohlfs M.,University of Gottingen | Churchill A.C.L.,Cornell University
Fungal Genetics and Biology | Year: 2011

Fungi share a diverse co-evolutionary history with animals, especially arthropods. In this review, we focus on the role of secondary metabolism in driving antagonistic arthropod-fungus interactions, i.e., where fungi serve as a food source to fungal grazers, compete with saprophagous insects, and attack insects as hosts for growth and reproduction. Although a wealth of studies on animal-fungus interactions point to a crucial role of secondary metabolites in deterring animal feeding and resisting immune defense strategies, causal evidence often remains to be provided. Moreover, it still remains an unresolved puzzle as to what extent the tight regulatory control of secondary metabolite formation in some model fungi represents an evolved chemical defense system favored by selective pressure through animal antagonists. Given these gaps in knowledge, we highlight some co-evolutionary aspects of secondary metabolism, such as induced response, volatile signaling, and experimental evolution, which may help in deciphering the ecological importance and evolutionary history of secondary metabolite production in fungi. © 2010 Elsevier Inc.

Noubactep C.,University of Gottingen | Noubactep C.,Kultur und Nachhaltige Entwicklung CDD e.V. | Care S.,University Paris Est Creteil
Journal of Hazardous Materials | Year: 2011

Despite the amount of data available on investigating the process of aqueous contaminant removal by metallic iron (Fe0), there is still a significant amount of uncertainty surrounding the design of Fe0 beds for laboratory testing to determine the suitability of Fe0 materials for field applications. Available data were obtained under various operating conditions (e.g., column characteristics, Fe0 characteristics, contaminant characteristics, oxygen availability, solution pH) and are hardly comparable to each other. The volumetric expansive nature of iron corrosion has been univocally reported as major drawback for Fe0 beds. Mixing Fe0 with inert materials has been discussed as an efficient tool to improve sustainability of Fe0 beds. This paper discusses some problems associated with the design of Fe0 beds and proposes a general approach for the characterization of Fe0 beds. Each Fe0 column should be characterized by its initial porosity, the composition of the steady phase and the volumetric proportion of individual materials. Used materials should be characterized by their density, porosity, and particle size. This work has introduced simple and reliable mathematical equations for column design, which include the normalisation of raw experimental data prior to any data treatment. © 2011 Elsevier B.V.

Bovino S.,University of Gottingen | Schleicher D.R.G.,University of Gottingen | Schober J.,University of Heidelberg
New Journal of Physics | Year: 2013

The small-scale dynamo provides a highly efficient mechanism for the conversion of turbulent into magnetic energy. In astrophysical environments, such turbulence often occurs at high Mach numbers, implying steep slopes in the turbulent spectra. It is thus a central question whether the small-scale dynamo can amplify magnetic fields in the interstellar or intergalactic media, where such Mach numbers occur. To address this long-standing issue, we employ the Kazantsev model for turbulent magnetic field amplification, systematically exploring the effect of different turbulent slopes, as expected for Kolmogorov, Burgers, the Larson laws and results derived from numerical simulations. With the framework employed here, we give the first solution encompassing the complete range of magnetic Prandtl numbers, including Pm ≪ 1, Pm ∼ 1 and Pm ≫ 1. We derive scaling laws of the growth rate as a function of hydrodynamic and magnetic Reynolds number for Pm ≪ 1 and Pm ≫ 1 for all types of turbulence. A central result concerns the regime of Pm ∼ 1, where the magnetic field amplification rate increases rapidly as a function of Pm. This phenomenon occurs for all types of turbulence we have explored. We further find that the dynamo growth rate can be decreased by a few orders of magnitude for turbulence spectra steeper than Kolmogorov. We calculate the critical magnetic Reynolds number Rmc for magnetic field amplification, which is highest for the Burgers case. As expected, our calculation shows a linear behaviour of the amplification rate close to the threshold proportional to (Rm - Rmc). On the basis of the Kazantsev model, we therefore expect the existence of the small-scale dynamo for a given value of Pm as long as the magnetic Reynolds number is above the critical threshold. © IOP Publishing and Deutsche Physikalische Gesellschaft.

Vollmer S.,University of Gottingen | Vollmer S.,Harvard University | Harttgen K.,ETH Zurich | Subramanyam M.A.,Indian Institute of Technology Gandhinagar | And 3 more authors.
The Lancet Global Health | Year: 2014

Background: Economic growth is widely regarded as a necessary, and often sufficient, condition for the improvement of population health. We aimed to assess whether macroeconomic growth was associated with reductions in early childhood undernutrition in low-income and middle-income countries. Methods: We analysed data from 121 Demographic and Health Surveys from 36 countries done between Jan 1, 1990, and Dec 31, 2011. The sample consisted of nationally representative cross-sectional surveys of children aged 0-35 months, and the outcome variables were stunting, underweight, and wasting. The main independent variable was per-head gross domestic product (GDP) in constant prices and adjusted for purchasing power parity. We used logistic regression models to estimate the association between changes in per-head GDP and changes in child undernutrition outcomes. Models were adjusted for country fixed effects, survey-year fixed effects, clustering, and demographic and socioeconomic covariates for the child, mother, and household. Findings: Sample sizes were 462 854 for stunting, 485 152 for underweight, and 459 538 for wasting. Overall, 35·6% (95% CI 35·4-35·9) of young children were stunted (ranging from 8·7% [7·6-9·7] in Jordan to 51·1% [49·1-53·1] in Niger), 22·7% (22·5-22·9) were underweight (ranging from 1·8% [1·3-2·3] in Jordan to 41·7% [41·1-42·3] in India), and 12·8% (12·6-12·9) were wasted (ranging from 1·2% [0·6-1·8] in Peru to 28·8% [27·5-30·0] in Burkina Faso). At the country level, no association was seen between average changes in the prevalence of child undernutrition outcomes and average growth of per-head GDP. In models adjusted only for country and survey-year fixed effects, a 5% increase in per-head GDP was associated with an odds ratio (OR) of 0·993 (95% CI 0·989-0·995) for stunting, 0·986 (0·982-0·990) for underweight, and 0·984 (0·981-0·986) for wasting. ORs after adjustment for the full set of covariates were 0·996 (0·993-1·000) for stunting, 0·989 (0·985-0·992) for underweight, and 0·983 (0·979-0·986) for wasting. These findings were consistent across various subsamples and for alternative variable specifications. Notably, no association was seen between per-head GDP and undernutrition in young children from the poorest household wealth quintile. ORs for the poorest wealth quintile were 0·997 (0·990-1·004) for stunting, 0·999 (0·991-1·008) for underweight, and 0·991 (0·978-1·004) for wasting. Interpretation: A quantitatively very small to null association was seen between increases in per-head GDP and reductions in early childhood undernutrition, emphasising the need for direct health investments to improve the nutritional status of children in low-income and middle-income countries. © 2014 Vollmer et al.

Noubactep C.,University of Gottingen | Noubactep C.,Kultur und Nachhaltige Entwicklung CDD e.V.
Journal of Hazardous Materials | Year: 2011

This letter challenges the concept that the metallic iron (Fe 0) surface contributes directly to the process of micro-organism inactivation in aqueous solutions. It is shown that any antimicrobial properties of Fe 0 is related to the cycle of expansion/contraction accompanying aqueous iron corrosion. This demonstration corroborates the concept that aqueous contaminant removal in the presence of Fe 0 mostly occurs at the Fe-oxide/water interface or within the oxide-film on Fe 0. © 2011 Elsevier B.V.

Cumming G.S.,University of Cape Town | Buerkert A.,University of Kassel | Hoffmann E.M.,University of Kassel | Schlecht E.,University of Gottingen | And 2 more authors.
Nature | Year: 2014

Historically, farmers and hunter-gatherers relied directly on ecosystem services, which they both exploited and enjoyed. Urban populations still rely on ecosystems, but prioritize non-ecosystem services (socioeconomic). Population growth and densification increase the scale and change the nature of both ecosystem- and non-ecosystem-service supply and demand, weakening direct feedbacks between ecosystems and societies and potentially pushing social-ecological systems into traps that can lead to collapse. The interacting and mutually reinforcing processes of technological change, population growth and urbanization contribute to over-exploitation of ecosystems through complex feedbacks that have important implications for sustainable resource use. © 2014 Macmillan Publishers Limited. All rights reserved.

Kieser M.,University of Heidelberg | Friede T.,University of Gottingen | Gondan M.,University of Heidelberg
Statistics in Medicine | Year: 2013

In drug development, it is well accepted that a successful study will demonstrate not only a statistically significant result but also a clinically relevant effect size. Whereas standard hypothesis tests are used to demonstrate the former, it is less clear how the latter should be established. In the first part of this paper, we consider the responder analysis approach and study the performance of locally optimal rank tests when the outcome distribution is a mixture of responder and non-responder distributions. We find that these tests are quite sensitive to their planning assumptions and have therefore not really any advantage over standard tests such as the t-test and the Wilcoxon-Mann-Whitney test, which perform overall well and can be recommended for applications. In the second part, we present a new approach to the assessment of clinical relevance based on the so-called relative effect (or probabilistic index) and derive appropriate sample size formulae for the design of studies aiming at demonstrating both a statistically significant and clinically relevant effect. Referring to recent studies in multiple sclerosis, we discuss potential issues in the application of this approach. © 2012 John Wiley & Sons, Ltd.

Noubactep C.,University of Gottingen | Noubactep C.,Kultur und Nachhaltige Entwicklung CDD e.V.
Chemical Engineering Journal | Year: 2010

A new concept for household and large-scale safe drinking water production is presented. Raw water is successively filtered through a series of sand and iron filters. Sand filters mostly remove suspended particles (media filtration) and iron filters remove anions, cations, micro-pollutants, natural organic matter, and micro-organisms including pathogens (reactive filtration). Accordingly, treatment steps conventionally achieved with flocculation, sedimentation, rapid sand filtration, activated carbon filtration, and disinfection are achieved in the new concept in only two steps. To prevent bed clogging, Fe0 is mixed with inert materials, yielding Fe0/sand filters. Efficient water treatment in Fe0/sand filters has been extensively investigated during the past two decades. Two different contexts are particularly important in this regard: (i) underground permeable reactive barriers and (ii) household water filters. In these studies, the process of aqueous iron corrosion in a packed bed was proven very efficient for unspecific aqueous contaminant removal. Been based on a chemical process (iron corrosion), efficient water treatment in Fe0 beds is necessarily coupled with a slow flow rate. Therefore, for large communities several filters should work in parallel to produce enough water for storage and distribution. It appears that water filtration through Fe0/sand filters is an efficient, affordable, a flexible technology for the whole world. © 2010 Elsevier B.V.

Clever G.H.,University of Gottingen | Kawamura W.,University of Tokyo | Tashiro S.,University of Tokyo | Shiro M.,Rigaku Co. | Shionoya M.,University of Tokyo
Angewandte Chemie - International Edition | Year: 2012

Neatly wrapped up: Alternately stacked square-planar platinum(II) complexes inside a dinuclear coordination cage were prepared to give a discrete and soluble Pt 5-array of the Magnus' salt type. Characterization of the complex in solution was complemented by an X-ray crystal structure of {[Pt(pyridine) 4]· [PtCl 4] 2@Cage}; this structure showed the linear, pentanuclear array within the cages and their circular packing into a hollow tubular superstructure. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Rodel C.,Goethe University Frankfurt | Hofheinz R.,University of Heidelberg | Liersch T.,University of Gottingen
Current Opinion in Oncology | Year: 2012

Purpose of review: To discuss the recent developments of multimodal treatment for patients with local advanced rectal cancer, including incorporation of new chemotherapeutic and targeted agents, and the optimal sequence and timing of treatment components. Recent findings: Five randomized trials have been completed to determine whether the addition of oxaliplatin to preoperative, fluorouracil-based chemoradiotherapy (CRT) offers an advantage compared to single-agent fluorouracil CRT. Early results from the ACCORD 12, STAR-01, and NSAPB R-04 trials did not confirm a significant improvement of early efficacy endpoints with the addition of oxaliplatin, whereas the German CAO/ARO/AIO-04 did. Most of the phase II trials incorporating cetuximab into CRT reported disappointingly low rates of pathologic complete response (pCR); the combination of CRT with VEGF inhibition showed encouraging pCR rates; however, it was associated with increased surgical complications. Novel clinical trials address the role of induction chemotherapy, of delayed, minimal or omitted surgery following CRT, or the omission of radiotherapy for selected patients. Summary: At this time, the use of oxaliplatin or targeted agents as component of multimodality treatment for rectal cancer outside of a clinical trial is not recommended. The inclusion of different treatment options, according to tumor stage, location, imaging features, and response, will render the multimodal treatment approach of rectal cancer more risk-adapted. © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins.

Noubactep C.,University of Gottingen | Noubactep C.,Kultur und Nachhaltige Entwicklung CDD e.V.
Clean - Soil, Air, Water | Year: 2013

Metallic iron (Fe0) is often reported as a reducing agent for environmental remediation. There is still controversy as to whether Fe0 plays any significant direct role in the process of contaminant reductive transformation. The view that Fe0 is mostly a generator of reducing agents (e.g. H, H2 and FeII) and Fe oxyhydroxides has been either severely refuted or just tolerated. The tolerance is based on the simplification that, without Fe0, no secondary reducing agents could be available. Accordingly, Fe0 serves as the original source of electron donors (including H, H2 and FeII). The objective of this communication is to refute the named simplification and establish that quantitative reduction results from secondary reducing agents. For this purpose, reports on aqueous contaminant removal by Al0, Fe0 and Zn0 are comparatively discussed. Results indicated that reduction may be quantitative in aqueous systems containing Fe0 and Zn0 while no significant reduction is observed in Al0/H2O systems. Given that Al0 is a stronger reducing agent than Fe0 and Zn0, it is concluded that contaminant reduction in Fe0/H2O systems results from synergic interactions between H/H2 and FeII within porous Fe oxyhydroxides. This conclusion corroborates the operating mode of Fe0 bimetallics as H/H2 producing systems for indirect contaminant reduction. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Hardeland R.,University of Gottingen | Madrid J.A.,University of Murcia | Tan D.-X.,University of Texas Health Science Center at San Antonio | Reiter R.J.,University of Texas Health Science Center at San Antonio
Journal of Pineal Research | Year: 2012

Evidence is accumulating regarding the importance of circadian core oscillators, several associated factors, and melatonin signaling in the maintenance of health. Dysfunction of endogenous clocks, melatonin receptor polymorphisms, age-and disease-associated declines of melatonin likely contribute to numerous diseases including cancer, metabolic syndrome, diabetes type 2, hypertension, and several mood and cognitive disorders. Consequences of gene silencing, overexpression, gene polymorphisms, and deviant expression levels in diseases are summarized. The circadian system is a complex network of central and peripheral oscillators, some of them being relatively independent of the pacemaker, the suprachiasmatic nucleus. Actions of melatonin on peripheral oscillators are poorly understood. Various lines of evidence indicate that these clocks are also influenced or phase-reset by melatonin. This includes phase differences of core oscillator gene expression under impaired melatonin signaling, effects of melatonin and melatonin receptor knockouts on oscillator mRNAs or proteins. Cross-connections between melatonin signaling pathways and oscillator proteins, including associated factors, are discussed in this review. The high complexity of the multioscillator system comprises alternate or parallel oscillators based on orthologs and paralogs of the core components and a high number of associated factors with varying tissue-specific importance, which offers numerous possibilities for interactions with melatonin. It is an aim of this review to stimulate research on melatonin signaling in peripheral tissues. This should not be restricted to primary signal molecules but rather include various secondarily connected pathways and discriminate between direct effects of the pineal indoleamine at the target organ and others mediated by modulation of oscillators. © 2011 John Wiley & Sons A/S.

Xu H.,Max Planck Institute for Dynamics and Self-Organization | Pumir A.,Ecole Normale Superieure de Lyon | Bodenschatz E.,Max Planck Institute for Dynamics and Self-Organization | Bodenschatz E.,University of Gottingen | Bodenschatz E.,Cornell University
Nature Physics | Year: 2011

The disorganized fluctuations of turbulence are crucial in the transport of particles or chemicals and could play a decisive role in the formation of rain in clouds, the accretion process in protoplanetary disks, and how animals find their mates or prey. These and other examples suggest a yet-to-be-determined unifying structure of turbulent flows. Here, we unveil an important ingredient of turbulence by taking the perspective of an observer who perceives its world with respect to three distant neighbours all swept by the flow. The time evolution of the observer's world can be decomposed into rotation and stretching. We show that, in this Lagrangian frame, the axis of rotation aligns with the initially strongest stretching direction, and that the dynamics can be understood by the conservation of angular momentum. This pirouette effect' thus appears as an important structural component of turbulence, and elucidates the mechanism for small-scale generation in turbulence. © 2011 Macmillan Publishers Limited. All rights reserved.

Metzner W.,Max Planck Institute for Solid State Research | Salmhofer M.,University of Heidelberg | Honerkamp C.,RWTH Aachen | Meden V.,RWTH Aachen | Schonhammer K.,University of Gottingen
Reviews of Modern Physics | Year: 2012

Numerous correlated electron systems exhibit a strongly scale-dependent behavior. Upon lowering the energy scale, collective phenomena, bound states, and new effective degrees of freedom emerge. Typical examples include (i) competing magnetic, charge, and pairing instabilities in two-dimensional electron systems; (ii) the interplay of electronic excitations and order parameter fluctuations near thermal and quantum phase transitions in metals; and (iii) correlation effects such as Luttinger liquid behavior and the Kondo effect showing up in linear and nonequilibrium transport through quantum wires and quantum dots. The functional renormalization group is a flexible and unbiased tool for dealing with such scale-dependent behavior. Its starting point is an exact functional flow equation, which yields the gradual evolution from a microscopic model action to the final effective action as a function of a continuously decreasing energy scale. Expanding in powers of the fields one obtains an exact hierarchy of flow equations for vertex functions. Truncations of this hierarchy have led to powerful new approximation schemes. This review is a comprehensive introduction to the functional renormalization group method for interacting Fermi systems. A self-contained derivation of the exact flow equations is presented and frequently used truncation schemes are described. Reviewing selected applications it is shown how approximations based on the functional renormalization group can be fruitfully used to improve our understanding of correlated fermion systems. © 2012 American Physical Society.

Mick D.U.,University of Gottingen | Fox T.D.,Cornell University | Rehling P.,University of Gottingen | Rehling P.,Max Planck Institute for Biophysical Chemistry
Nature Reviews Molecular Cell Biology | Year: 2011

Mitochondria maintain genome and translation machinery to synthesize a small subset of subunits of the oxidative phosphorylation system. To build up functional enzymes, these organellar gene products must assemble with imported subunits that are encoded in the nucleus. New findings on the early steps of cytochrome c oxidase assembly reveal how the mitochondrial translation of its core component, cytochrome c oxidase subunit 1 (Cox1), is directly coupled to the assembly of this respiratory complex. © 2011 Macmillan Publishers Limited. All rights reserved.

Doehner W.,Charité - Medical University of Berlin | Frenneaux M.,University of Aberdeen | Anker S.D.,University of Gottingen
Journal of the American College of Cardiology | Year: 2014

Although bioenergetic starvation is not a new concept in heart failure (HF), recent research has led to a growing appreciation of the complexity of metabolic aspects of HF pathophysiology. All steps of energy extraction, transfer, and utilization are affected, and structural metabolism is impaired, leading to compromised functional integrity of tissues. Not only the myocardium, but also peripheral tissues and organs are affected by metabolic failure, resulting in a global imbalance between catabolic and anabolic signals, leading to tissue wasting and, ultimately, to cachexia. Metabolic feedback signals from muscle and fat actively contribute to further myocardial strain, promoting disease progression. The prolonged survival of patients with stable, compensated HF will increasingly bring chronic metabolic complications of HF to the fore and gradually shift its clinical presentation. This paper reviews recent evidence on myocardial and systemic metabolic impairment in HF and summarizes current and emerging therapeutic concepts with specific metabolic targets. © 2014 American College of Cardiology Foundation.

Grimmsmann T.,Review-Board | Himmel W.,University of Gottingen
European Journal of Clinical Pharmacology | Year: 2014

Purpose: To study drug persistence for antihypertensive treatment considering typical patient behaviour including extended drug holidays or irregular repeat prescriptions. Methods: We used prescription data from a German statutory health insurance to follow up patients for 4 years. Medication persistence was defined as the continued use of a specific drug class, therapy persistence as the continued use of any antihypertensive drug. We applied 2 different interval criteria within which a repeat prescription had to be issued: 180 and 360 days. Results: A total of 9,513 patients started an antihypertensive therapy between 2006 and 2008. Applying the 180-day (360-day) interval criterion, 28 % (66 %) of the patients starting therapy with a beta-blocker were still medication-persistent after 4 years. The rates were similar for angiotensin-II receptor blockers (ARBs; 30 % and 69 % respectively) or angiotensin-converting enzyme (ACE) inhibitors (28 % and 61 % respectively). Looking at therapy persistence, these rates were 44 % (79 %) when an ACE inhibitor was the initial drug, 46 % (82 %) for ARBs. On average, even of those who were defined as therapeutically persistent with the 360 days criterion, half received a repeat prescription within 96 days, three quarters within 131 days - with a median supply of 1.2 units per day and 1.25 defined daily doses. Conclusion: By applying more patient-orientated criteria, we found that many patients were therapy-persistent and received a prescription at the appropriate time. Therapy persistence was nearly independent of the initial agent; thus, drug persistence may not be an argument in favour of choosing a certain drug as a first-line option. © 2013 Springer-Verlag Berlin Heidelberg.

Noubactep C.,University of Gottingen | Noubactep C.,Kultur und Nachhaltige Entwicklung CDD e.V.
Water Research | Year: 2015

This article critically evaluates recent review articles on using metallic iron (Fe0) for environmental remediation in order to provide insight for more efficient Fe0-based systems. The presentation is limited to peer-reviewed articles published during 2014 and 2015, excluding own contributions, dealing mostly with granular Fe0. A literature search was conducted up to June 15th 2015 using Science Direct, SCOPUS, Springer and Web of Science databases. The search yielded eight articles that met the final inclusion criteria. The evaluation clearly shows that seven articles provide a narrative description of processes occurring in the Fe0/H20 system according to the concept that Fe0 is a reducing agent. Only one article clearly follows a different path, presenting Fe0 as a generator of adsorbing (hydroxides, oxides) and reducing (FeII, H/H2) agents. The apparent discrepancies between the two schools are identified and extensively discussed based on the chemistry of the Fe0/H20 system. The results of this evaluation indicate clearly that research on 'Fe0 for environmental remediation' is in its infancy. Despite the current paucity of reliable data for the design of efficient Fe0-based systems, this review demonstrates that sensible progress could be achieved within a short period of time, specific recommendations to help guide future research are suggested. © 2015 Elsevier Ltd.

Noubactep C.,University of Gottingen | Noubactep C.,Kultur und Nachhaltige Entwicklung CDD e.V.
Chemosphere | Year: 2014

Use of metallic iron (Fe(0)) for water treatment has attracted much attention over the passed two decades. Achieved results have recalled that the formation of voluminous, low-soluble iron oxides and hydroxides within the system is ubiquitous at pH. >. 4.0. These properties imply that efficiency and porosity of Fe(0)-based filtration systems will decrease in the long-term. Some methods have been suggested to solve the identified problems. However, they could be collectively regarded as weak because they are based on a false description of the system. This note reveals two major inherent flaws in the design of Fe(0)-based filters and shows ways to fix them. © 2014 Elsevier Ltd.

Solli D.R.,University of California at Los Angeles | Solli D.R.,University of Gottingen | Jalali B.,University of California at Los Angeles | Ropers C.,University of Gottingen
Physical Review Letters | Year: 2010

The transition between modulation instability gain and induced soliton fission in nonlinear fiber is experimentally investigated by coherent seeding with the two-color output of an optical parametric oscillator. This approach produces supercontinuum spectra displaying persistent, fine modulation from seeding-induced noise reduction. Numerical simulations support the findings. © 2010 The American Physical Society.

Dutsch M.,University of Gottingen | Gracia-Bondia J.M.,University of Zaragoza | Gracia-Bondia J.M.,Institute Fisica Teorica
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2012

Out of conviction or expediency, some current research programs (Kostelecký (2008) . [1], Kostelecký and Russell (2011) . [2], Ferrero and Altschul (2011) . [3], Anselmi (2009) . [4]) take for granted that "PCT violation implies violation of Lorentz invariance". We point out that this claim (Greenberg (2002) . [5]) is still on somewhat shaky ground. In fact, for many years there has been no strengthening of the evidence in this direction. However, using causal perturbation theory, we prove here that when starting with a local PCT-invariant interaction, PCT symmetry can be maintained in the process of renormalization. © 2012 Elsevier B.V.

Noubactep C.,University of Gottingen | Noubactep C.,Kultur und Nachhaltige Entwicklung CDD e.V.
Clean - Soil, Air, Water | Year: 2013

Water treatment with metallic iron (Fe0) is still based on the premise that Fe0 is a reducing agent. An alternative concept stipulates that contaminants are removed by adsorption, co-precipitation, and size-exclusion in a reactive filtration process. This article underlines the universal validity of the alternative concept. It is shown that admixing non-expansive material to Fe0 as a pre-requisite for sustainable Fe0-based filtration systems. Fe0-based filters are demonstrated an affordable, appropriate, and efficient decentralized water treatment technology. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Solli D.R.,University of California at Los Angeles | Solli D.R.,University of Gottingen | Herink G.,University of Gottingen | Jalali B.,University of California at Los Angeles | And 2 more authors.
Nature Photonics | Year: 2012

Stochastically driven nonlinear processes are responsible for spontaneous pattern formation and instabilities in numerous natural and artificial systems, including well-known examples such as sand ripples, cloud formations, water waves, animal pigmentation and heart rhythms. Technologically, a type of such self-amplification drives free-electron lasers and optical supercontinuum sources whose radiation qualities, however, suffer from the stochastic origins. Through time-resolved observations, we identify intrinsic properties of these fluctuations that are hidden in ensemble measurements. We acquire single-shot spectra of modulation instability produced by laser pulses in glass fibre at megahertz real-time capture rates. The temporally confined nature of the gain physically limits the number of amplified modes, which form an antibunched arrangement as identified from a statistical analysis of the data. These dynamics provide an example of pattern competition and interaction in confined nonlinear systems. © 2012 Macmillan Publishers Limited. All rights reserved.

Hardeland R.,University of Gottingen | Cardinali D.P.,Pontifical Catholic University of Argentina | Brown G.M.,University of Toronto | Pandi-Perumal S.R.,New York University
Progress in Neurobiology | Year: 2015

Melatonin is known to possess several properties of value for healthy aging, as a direct and indirect antioxidant, protectant and modulator of mitochondrial function, antiexcitotoxic agent, enhancer of circadian amplitudes, immune modulator and neuroprotectant. It is levels tend to decrease in the course of senescence and are more strongly reduced in several neurodegenerative disorders, especially Alzheimer's disease, and in diseases related to insulin resistance such as diabetes type 2. Although the role of melatonin in aging and age-related diseases has been repeatedly discussed, the newly emerged concept of inflammaging, that is, the contribution of low-grade inflammation to senescence progression has not yet been the focus of melatonin research. This review addresses the multiple protective actions of melatonin and its kynuramine metabolites that are relevant to the attenuation of inflammatory responses and progression of inflammaging in the brain, i.e. avoidance of excitotoxicity, reduction of free radical formation by support of mitochondrial electron flux, prevention of NADPH oxidase activation and suppression of inducible nitric oxide synthase, as well as downregulation of proinflammatory cytokines. The experimental evidence is primarily discussed on the basis of aging and senescence-accelerated animals, actions in the immune system, and the relationship between melatonin and sirtuins, having properties of aging suppressors. Sirtuins act either as accessory components or downstream factors of circadian oscillators, which are also under control by melatonin. Inflammaging is assumed to strongly contribute to neurodegeneration of the circadian master clock observed in advanced senescence and, even more, in Alzheimer's disease, a change that affects countless physiological functions. © 2015 Elsevier Ltd.

Gleiter R.,University of Heidelberg | Werz D.B.,University of Gottingen
Chemical Reviews | Year: 2010

The study presents (oligo)alkynes capped with main group elements except carbon atoms. The functionalization of many species with a terminal alkyne group proceeds via metalation of the terminal C(sp) carbon. The bis(dialkylboron) acetylenes are prepared by the reaction of dialkylboron iodide with acetylene dimagnesiumdibromide and the resulting alkynes are obtained in moderate yields. A more straightforward synthesis of diborylacetylenes is reported by reacting 2-chloro-1,2,3-benzodioxaborole or the congeners with bis(trimethylstannyl) acetylene. The substitution of the cobaltacarboranes at the 5- and 7-positions by halogen is used to prepare the carbon wired planar octagon. 1,2-dichlorodisilanes with carbon tethers are reacted with bis(bromomagnesium) acetylide to obtain a mixture of cyclic diynes, triynes, and tetraynes and also higher oligomers in low yield.

Kessler A.,Cornell University | Halitschke R.,Cornell University | Poveda K.,University of Gottingen
Ecology | Year: 2011

Abstract. Although induced plant responses to herbivory are well studied as mechanisms of resistance, how induction shapes community interactions and ultimately plant fitness is still relatively unknown. Using a wild tomato, Solanum peruvianum, native to the Peruvian Andes, we evaluated the disruption of pollination as a potential ecological cost of induced responses. More specifically, we tested the hypothesis that metabolic changes in herbivore-attacked plants, such as the herbivore-induced emission of volatile organic compounds (VOCs), alter pollinator behavior and consequentially affect plant fitness. We conducted a series of manipulative field experiments to evaluate the role of herbivore-induced vegetative and floral VOC emissions as mechanisms by which herbivory affects pollinator behavior. In field surveys and bioassays in the plants' native habitat, we found that real and simulated herbivory (methyl jasmonate application) reduced attractiveness of S. peruvianum flowers to their native pollinators. We show that reduced pollinator preference, not resource limitation due to leaf tissue removal, resulted in reduced seed set. Solitary bee pollinators use floral plant volatiles, emitted in response to herbivory or methyl jasmonate treatment, as cues to avoid inflorescences on damaged plants. This herbivory-induced pollinator limitation can be viewed as a general cost of induced plant responses as well as a specific cost of herbivory-induced volatile emission. © 2011 by the Ecological Society of America.

Noubactep C.,University of Gottingen | Noubactep C.,Kultur und Nachhaltige Entwicklung CDD e.V.
Korean Journal of Chemical Engineering | Year: 2012

The instability of the premise of direct quantitative contaminant reduction by elemental iron (Fe 0) materials in Fe 0/H 2O systems is pointed out. Basic knowledge of aqueous iron corrosion shows that the Fe 0 surface is not available for decontamination in nature. A comparison of the reactivity of Fe 0 and Zn 0 shows that the effectiveness of Fe 0 materials for environmental remediation is due to the formation of a non-adhesive, porous oxide scale on Fe 0. Contaminants are enmeshed within the scale and possibly reduced by Fe II and H/H 2. An evaluation of current experimental conditions shows that well-mixed batch systems have disturbed the process of scale formation. Therefore, the majority of published works have operatively created conditions for contaminant reduction that are not likely to occur in nature. Since working under such unrealistic conditions has mediated the above-mentioned premise, interactions in Fe 0/H 2O systems yielding contaminant removal should be revisited. © 2012 Korean Institute of Chemical Engineers, Seoul, Korea.

Gerwick E.,University of Edinburgh | Plehn T.,University of Heidelberg | Schumann S.,University of Heidelberg | Schumann S.,University of Gottingen
Physical Review Letters | Year: 2012

Jet counting and jet vetos are crucial analysis tools for many LHC searches. We can understand their properties from the distribution of the exclusive number of jets. LHC processes tend to show either a distinct staircase scaling or a Poisson scaling, depending on kinematic cuts. We illustrate our approach in a detailed study of jets in weak boson fusion Higgs production. © 2012 American Physical Society.

News Article | December 10, 2016

Donald Trump has sent some mixed signals on China. One minute they are “raping” America, the next they are his best clients. Even the way he says the word – and he says it a lot – seeds confusion. Sometimes the president-elect spits it out like poison, sometimes he exclaims the word as if greeting a favoured child. Whatever his real attitude, those that study the world’s second-largest economy believe US-China relations are in for a rocky time when Trump reaches the White House – and the global consequences could be dire. Trump excoriated China’s trade policies during his election campaign and succeeded in needling Beijing into threats of retaliation after pledging to whack a 45% tariff on Chinese imports. The president-elect rattled Beijing again earlier this month after taking a call from Taiwanese president Tsai Ing-wen – the first communication between top officials from the two governments in nearly 40 years. Last week he seemed to be attempting to mend fences, appointing Iowa governor Terry Branstad, “an old friend of the Chinese people” according to Beijing officials, as his ambassador to China. But such a signal has not been enough to head off worries of a looming trade war between China and the US that would send shockwaves across the globe. “The initial signs are not good,” said Minxin Pei, professor of government at Claremont McKenna College in California and author of the book China’s Crony Capitalism. The US has recognised Taiwan as part of China since 1979 and its status is “non-negotiable”, said Pei. Branstad is an interesting pick and “shows a gesture that he wants to keep the relationship on an even keel”. But Pei said descriptions of Branstad as a longtime friend of Chinese leader Xi Jinpin were overblown. “That’s a very American way of describing friendship. Very few Chinese leaders have longtime friends,” he said. “What China really values in an ambassador is not his relationship with them but his relationship with the White House.” Those doing business with the two trading powers will have a lot invested in the pro-trade Branstad’s powers of persuasion. Academic studies have already shown the consequences of political spats with Beijing. In 2010 the University of Gottingen in Germany coined the term “the Dalai Lama effect” after its study found countries whose top leadership met with Tibet’s exiled spiritual leader lost on average 8.1% in exports to China in the two years following the meeting. The first true test of the Trump White House’s relationship with China may come in April, when the US Treasury releases a report looking at China’s currency. Trump has long maintained that China has been devaluing its currency in order to stack the deck on exports in its favour. “If he wants to impose tariffs on China, he needs a procedural excuse. He can’t just get into the White House and the next day announce a tariff increase, it wouldn’t look good,” said Pei. Allegations of Chinese currency manipulation are out of date and largely incorrect, according to Pei. In fact, Beijing has been burning through its currency reserves in an attempt to prop up the value of the yuan. “But for Donald Trump that doesn’t matter. Intellectual rigour is not one of his concerns.” Louis Kuijs, head of Asia economics at Oxford Economics and a former senior China economist at the World Bank, said it was “more legitimate now than at anytime in the last 10 years to talk about the risk of something pretty close to a trade war”, he said. “Anyone with a stake in Chinese exports, especially to the US, should be worried,” said Kuijs, adding that US and European companies that assemble products in China would also see their bottom lines affected. If a trade war starts, it is likely to start with targeted hits, said Pei. If Trump wants to placate his base in the midwest he could target Chinese steel, for example. China is engaging “in at least questionable” practices in the steel industry, says Pei. “The industry has so much overcapacity and they are exporting a lot of cheap steel and that is disrupting.” If the moves are small enough, China might chose to ignore them and concentrate on the bigger picture. But past at a certain point, Beijing will retaliate and would likely target large American firms, Boeing or Apple for example, that increasingly rely on China. Both sides have a lot to lose in a trade war. China is currently the US’s largest goods trading partner. Trade between the two was worth $598bn in total during 2015, with US exports to China totalling $116bn and imports totalling $482bn. China has more to lose but the types of goods it sells to the US are harder to source elsewhere. The three largest categories of goods China buys from the US are soybeans, cars and aircraft, all of which China could source from elsewhere. The three largest categories that the US imports from China are mobile phones, tablets/laptops and network equipment. “In each case, China is the dominant global supplier, producing about 70% of global output. A high tariff would end up as effectively a tax on US purchases of consumer electronics,” Capital Economics’ chief Asia economist wrote in a recent note to investors. Tariffs on those goods would also disrupt trade right across the Asia Pacific region, said Pei. Some 35% of China’s exports in 2015 was “processing trade”, where China imports components from other countries and assembles them for exports. A trade war with China on those goods would cause collateral damage on imports from Japan, South Korea, Taiwan and others. While both sides would suffer, China’s economy is more reliant on US exports and a serious spat would rock the economy at a time of sluggish growth. Household debt has soared as property prices have increased, and millions of workers are set to lose their jobs as the government seeks to rebalance the economy away from state-led investments. Not all factory owners in China are worried about an upcoming trade war. “Trump’s grandstanding performances during the campaign were for publicity, but he’s a successful businessman and therefore should be very rational in his thinking,” said Sun Sijun, chief executive of Uptop Group in southern China, which exports between $150m-$200m worth of Samsonite suitcases and Walmart shoes to the US every year. “Rationally, the basic interests are not to make enemies, and to ultimately not harm yourself,” he said. “Trump’s talk of increasing tariffs is in the hope of increasing employment in America,” Sun said. “But there’s a very small probability you can bring these labour-intensive industries back to the US. Labour-intensive industries flowed to third world, and they won’t return to America.” But other producers in China see only dark clouds on the horizon. Chen Yadong also sells to Walmart. His company, Indena, makes computer mice and bluetooth speakers, sending more than 1m mice to the US each year. “I’m extremely worried,” Chen said from the electronics manufacturing hub of Shenzhen in southern China. “The US is the largest market for export-oriented companies here. If Trump increases tariffs, then this business will become increasingly difficult.” China’s leaders don’t know what to think of Trump quite yet, said Pei. But they do understand the consequences of a trade war. “The Chinese have a proverb: ‘you lift a rock only to drop it on your own foot.’”

Raupach T.,University of Gottingen | Hoogsteder P.H.J.,Maastricht University | Van Schayck C.P.O.,Maastricht University
Drugs | Year: 2012

Tobacco smoking causes cardiovascular, respiratory and malignant disease, and stopping smoking is among the key medical interventions to lower the worldwide burden of these disorders. However, the addictive properties of cigarette smoking, including nicotine inhalation, render most quit attempts unsuccessful. Recommended therapies, including combinations of counselling and medication, produce long-term continuous abstinence rates of no more than 30. Thus, more effective treatment options are needed.An intriguing novel therapeutic concept is vaccination against nicotine. The basic principle of this approach is that, after entering the systemic circulation, a substantial proportion of nicotine can be bound by antibodies. Once bound to antibodies, nicotine is no longer able to cross the blood-brain barrier. As a consequence, the rewarding effects of nicotine are diminished, and relapse to smoking is less likely to occur. Animal studies indicate that antibodies profoundly change the pharmacokinetics of the drug and can interfere with nicotine self-administration and impact on the severity of withdrawal symptoms. To date, five phase III clinical trials using vaccines against nicotine have been published. Results have been disappointing in that an increase in quit rates was only observed in small groups of smokers displaying particularly high antibody titres.The failure of encouraging preclinical data to completely translate to clinical studies may be partially explained by shortcomings of animal models of addiction and an incomplete understanding of the complex physiological and behavioural processes contributing to tobacco addiction. This review summarizes the current status of research and suggests some directions for the future development of vaccines against nicotine. Ideally, these vaccines could one day become part of a multifaceted approach to treating tobacco addiction that includes counselling and pharmacotherapy. © 2012 Adis Data Information BV. All rights reserved.

Getzin S.,University of Gottingen | Wiegand K.,University of Gottingen | Schoning I.,Friedrich - Schiller University of Jena
Methods in Ecology and Evolution | Year: 2012

1. Structural diversity and niche differences within habitats are important for stabilizing species coexistence. However, land-use change leading to environmental homogenization is a major cause for the dramatic decline of biodiversity under global change. The difficulty in assessing large-scale biodiversity losses urgently requires new technological advances to evaluate land-use impact on diversity timely and efficiently across space. 2. While cost-effective aerial images have been suggested for potential biodiversity assessments in forests, correlation of canopy object variables such as gaps with plant or animal diversity has so far not been demonstrated using these images. 3. Here, we show that aerial images of canopy gaps can be used to assess floristic biodiversity of the forest understorey. This approach is made possible because we employed cutting-edge unmanned aerial vehicles and very high-resolution images (7cmpixel -1) of the canopy properties. We demonstrate that detailed, spatially implicit information on gap shape metrics is sufficient to reveal strong dependency between disturbance patterns and plant diversity (R 2 up to 0·74). This is feasible because opposing disturbance patterns such as aggregated and dispersed tree retention directly correspond to different functional and dispersal traits of species and ultimately to different species diversities. 4. Our findings can be used as a coarse-filter approach to conservation in forests wherever light strongly limits regeneration and biodiversity. © 2011 The Authors. Methods in Ecology and Evolution © 2011 British Ecological Society.

Buchholz D.,University of Gottingen | Lechner G.,University of Vienna | Summers S.J.,University of Florida
Communications in Mathematical Physics | Year: 2011

Warped convolutions of operators were recently introduced in the algebraic framework of quantum physics as a new constructive tool. It is shown here that these convolutions provide isometric representations of Rieffel's strict deformations of C*-dynamical systems with automorphic actions of ℝn, whenever the latter are presented in a covariant representation. Moreover, the device can be used for the deformation of relativistic quantum field theories by adjusting the convolutions to the geometry of Minkowski space. The resulting deformed theories still comply with pertinent physical principles and their Tomita-Takesaki modular data coincide with those of the undeformed theory; but they are in general inequivalent to the undeformed theory and exhibit different physical interpretations. © 2010 The Author(s).

Shiraishi F.,University of Gottingen | Shiraishi F.,Hiroshima University
Geochimica et Cosmochimica Acta | Year: 2012

Chemical conditions favoring photosynthesis-induced CaCO 3 precipitation (PCP) was examined to provide basic knowledge for understanding ancient ocean chemistry that enabled microbial carbonate formation. First, numerical simulations were conducted to examine the property of photosynthetic increase in CaCO 3 saturation state (ΔΩ), an indicator for PCP introduced by previous studies. These simulations revealed that ΔΩ attained a high value at high Ca 2+ concentration, low ionic strength, and optimum pH and dissolved inorganic carbon (DIC) where a low-DIC effect and CO 2/CO 3 2- buffering were insignificant. Second, microelectrode measurements were conducted using cyanobacteria-dominated stromatolite to examine the property of actual PCP. Although Ca 2+ concentration and ionic strength similarly affected actual PCP, the influences of pH and DIC were quite different from what was expected from simulations: significant PCP occurred even at high DIC (up to ~300mmolL -1) where the ΔΩ increase was suppressed by CO 2/CO 3 2- buffering. Instead, actual PCP reflected the photosynthetically achieved saturation state (Ω aft), which is the sum of ΔΩ and initial saturation state (Ω bef). Thus, the chemical conditions favoring PCP is an optimum pH-DIC condition where ΔΩ achieves a high value and/or a high pH-DIC condition where Ω bef achieves a high value, in addition to a sufficiently high Ca 2+ concentration and low ionic strength. The microelectrode measurements also revealed that the photosynthetic pH increase did not always reflect the occurrence and significance of PCP. © 2011 Elsevier Ltd.

Eckstein A.,University of Duisburg - Essen | Schittkowski M.,University of Gottingen | Esser J.,University of Duisburg - Essen
Best Practice and Research: Clinical Endocrinology and Metabolism | Year: 2012

The aims of surgical treatment in Graves's orbitopathy (GO) are improvement of function and appearance. Since antiinflammatory treatment of GO rarely results in a complete resolution of symptoms, surgical treatment is very important for patients well being. Rehabilitative surgery includes orbital decompression, squint correction, lid lengthening and blepharoplasty and these procedures have to be performed in centres of expertise. Various techniques have been developed for orbital decompression which allow now a graded approach to proptosis reduction and optic nerve decompression in emergency situations. Extraocular muscle recessions can be successfully performed to treat most of the patients with diplopia. Only large or complex squint angles are difficult to treat and step by step procedures are recommended in these patients. Lid lengthening procedures are performed most often in GO patients and should be performed under local anaesthesia to get a good result. Serious complications are rare. © 2011 Elsevier Ltd. All rights reserved.

Giebel B.,University of Duisburg - Essen | Wodarz A.,University of Gottingen
Current Biology | Year: 2012

During Drosophila sensory organ precursor cell development, Numb segregates asymmetrically and functions as a cell fate determinant. Recent work now demonstrates in vivo that Numb inactivates Notch by promoting its endocytosis. © 2012 Elsevier Ltd. All rights reserved.

Boehncke W.-H.,University of Geneva | Schon M.P.,University of Gottingen
The Lancet | Year: 2015

Psoriasis is an immune-mediated, genetic disease manifesting in the skin or joints or both. A diverse team of clinicians with a range of expertise is often needed to treat the disease. Psoriasis provides many challenges including high prevalence, chronicity, disfiguration, disability, and associated comorbidity. Understanding the role of immune function in psoriasis and the interplay between the innate and adaptive immune system has helped to manage this complex disease, which affects patients far beyond the skin. In this Seminar, we highlight the clinical diversity of psoriasis and associated comorbid diseases. We describe recent developments in psoriasis epidemiology, pathogenesis, and genetics to better understand present trends in psoriasis management. Our key objective is to raise awareness of the complexity of this multifaceted disease, the potential of state-of-the-art therapeutic approaches, and the need for early diagnosis and comprehensive management of patients with psoriasis. © 2015 Elsevier Ltd.

Raupach T.,University of Gottingen | Van Schayck C.P.,Maastricht University
CNS Drugs | Year: 2011

Promoting smoking cessation is among the key medical interventions aimed at reducing worldwide morbidity and mortality in this century. Both behavioural counselling and pharmacotherapy have been shown to significantly increase long-term abstinence rates, and combining the two treatment modalities is recommended. This article provides an update on pharmacotherapy for smoking cessation in the general population.Current first-line agents used to support quit attempts are nicotine replacement therapy (NRT), bupropion and varenicline. Research suggests that abstinence rates can be increased by combining different forms of NRT or simultaneously administering NRT and non-nicotine medications. New treatments targeting the nicotinic acetylcholine receptor as well as other pathophysiological pathways involved in nicotine addiction are being developed, with nicotine vaccines now being tested in phase III clinical trials.Among the numerous research topics currently addressed, pharmacogenetics and tailoring therapy to specific groups of smokers look most promising. However, substantial progress is unlikely to be made unless social gradients impeding effective treatment of all smokers are overcome. In addition, public smoking bans and reimbursement of medication costs are crucial in reducing the future burden of disease caused by smoking on a global level. © 2011 Adis Data Information BV. All rights reserved.

Meier I.C.,University of Gottingen | Meier I.C.,Indiana University Bloomington | Leuschner C.,University of Gottingen
Global Change Biology | Year: 2010

Temperate forests have recently been identified as being continuing sinks for carbon even in their mature and senescent stages. However, modeling exercises indicate that a warmer and drier climate as predicted for parts of Central Europe may substantially alter the source/sink function of these economically important ecosystems. In a transect study with 14 mature European beech (Fagus sylvatica L.) forests growing on uniform geological substrate, we analyzed the influence of a large reduction of annual precipitation (970-520 mm yr-1) on the carbon stocks in fast and slow pools, independent of the well-known aging effect. We investigated the C storage in the organic L, F, H layers, the mineral soil to 100 cm, and in the biomass (stem, leaves, fine roots), and analyzed the dependence of these pools on precipitation. Soil organic carbon decreased by about 25% from stands with > 900 mm yr-1 to those with < 600 mm yr-1; while the carbon storage in beech stems slightly increased. Reduced precipitation affected the biomass C pool in particular in the fine root fraction but much less in the leaf biomass and stem fractions. Fine root turnover increased with a precipitation reduction, even though stand fine root biomass and SOC in the organic L, F, and H layers decreased. According to regression analyses, the C storage in the organic layers was mainly controlled by the size of the fine root C pool suggesting an important role of fine root turnover for the C transfer from tree biomass to the SOC pool. We conclude that the long-term consequence of a substantial precipitation decrease would be a reduction of the mineral soil and organic layer SOC pools, mainly due to higher decomposition rates. This could turn temperate beech forests into significant carbon sources instead of sinks under global warming. © 2009 Blackwell Publishing Ltd.

Martinez-Zarzoso I.,University of Gottingen | Martinez-Zarzoso I.,Jaume I University | Maruotti A.,Third University of Rome
Ecological Economics | Year: 2011

This paper analyzes the impact of urbanization on CO2 emissions in developing countries from 1975 to 2003. It contributes to the existing literature by examining the effect of urbanization, taking into account dynamics and the presence of heterogeneity in the sample of countries. The results show an inverted-U shaped relationship between urbanization and CO2 emissions. Indeed, the elasticity emission-urbanization is positive for low urbanization levels, which is in accordance with the higher environmental impact observed in less developed regions. Among our contributions is the estimation of a semi-parametric mixture model that allows for unknown distributional shapes and endogenously classifies countries into homogeneous groups. Three groups of countries are identified for which urbanization's impact differs considerably. For two of the groups, a threshold level is identified beyond which the emission-urbanization elasticity is negative and further increases in the urbanization rate do not contribute to higher emissions. However, for the third group only population and affluence, but not urbanization, contribute to explain emissions. The differential impact of urbanization on CO2 emissions should therefore be taken into account in future discussions of climate change policies. © 2011 Elsevier B.V.

Phillips R.P.,Indiana University Bloomington | Meier I.C.,Indiana University Bloomington | Meier I.C.,University of Gottingen | Bernhardt E.S.,Duke University | And 3 more authors.
Ecology Letters | Year: 2012

A common finding in multiple CO2 enrichment experiments in forests is the lack of soil carbon (C) accumulation owing to microbial priming of 'old' soil organic matter (SOM). However, soil C losses may also result from the accelerated turnover of 'young' microbial tissues that are rich in nitrogen (N) relative to bulk SOM. We measured root-induced changes in soil C dynamics in a pine forest exposed to elevated CO2 and N enrichment by combining stable isotope analyses, molecular characterisations of SOM and microbial assays. We find strong evidence that the accelerated turnover of root-derived C under elevated CO2 is sufficient in magnitude to offset increased belowground inputs. In addition, the C losses were associated with accelerated N cycling, suggesting that trees exposed to elevated CO2 not only enhance N availability by stimulating microbial decomposition of SOM via priming but also increase the rate at which N cycles through microbial pools. © 2012 Blackwell Publishing Ltd.

Rutherford M.A.,Central Washington University | Rutherford M.A.,University of Gottingen
Synapse | Year: 2015

Synapses are diverse in form and function; however, the mechanisms underlying this diversity are poorly understood. To illuminate structure/function relationships, robust analysis of molecular composition and morphology is needed. The molecular-anatomical components of synapses-vesicles, clusters of voltage-gated ion channels in presynaptic densities, arrays of transmitter receptors in postsynaptic densities-are only tens to hundreds of nanometers in size. Measuring the topographies of synaptic proteins requires nanoscale resolution of their molecularly specific labels. Super-resolution light microscopy has emerged to meet this need. Achieving 50 nm resolution in thick tissue, we employed stimulated emission depletion (STED) microscopy to image the functionally and molecularly unique ribbon-type synapses in the inner ear that connect mechano-sensory inner hair cells to cochlear nerve fibers. Synaptic ribbons, bassoon protein, voltage-gated Ca2+ channels, and glutamate receptors are inhomogeneous in their spatial distributions within synapses; the protein clusters assume variations of shapes typical for each protein specifically at cochlear afferent synapses. Heterogeneity of substructure among these synapses may contribute to functional differences among auditory nerve fibers. The morphology of synaptic voltage-gated Ca2+ channels matures over development in a way that depends upon bassoon protein, which aggregates in similar form. Functional properties of synaptic transmission appear to depend on voltage-gated Ca2+ channel cluster morphology and position relative to synaptic vesicles. Super-resolution light microscopy is a group of techniques that complement electron microscopy and conventional light microscopy. Although technical hurdles remain, we are beginning to resolve the details of molecular nanoanatomy that relate mechanistically to synaptic function. © 2015 Wiley Periodicals, Inc.

Schulz R.,University of Gottingen | Moll U.M.,University of Gottingen | Moll U.M.,State University of New York at Stony Brook
Current Opinion in Oncology | Year: 2014

PURPOSE OF REVIEW: Macrophage migration inhibitory factor (MIF), originally identified as a proinflammatory cytokine, is highly elevated in many human cancer types, independent of their histological origin. MIF's tumour promoting activities correlate with tumour aggressiveness and poor clinical prognosis. Genetic depletion of MIF in mouse cancer models results in significant inhibition of cell proliferation and induction of apoptosis, making it an attractive target for anticancer therapies. Here, we summarize the current possibilities to inhibit MIF function in cancer. RECENT FINDINGS: All known small molecule MIF inhibitors antagonize MIF's enzymatic function. However, a recent knockin mouse model suggested that protein interactions play a bigger biological role in tumour cell growth regulation than MIF's enzymatic activity. Thus, alternative strategies are important for targeting MIF. Recently, we identified that MIF in cancer cells is highly stabilized through the heat shock protein 90 machinery (HSP90). Thus, MIF is an HSP90 client. Pharmacological inhibition of the Hsp90 ATPase activity results in MIF degradation in several types of cancer cells. This provides a new way to inhibit MIF function independent of its enzymatic activity. SUMMARY: Targeting the HSP90 machinery is a promising way to inhibit MIF function in cancer. Along with MIF and dependent on the molecular make-up of the tumour, a large number of other critical tumourigenic proteins are also destabilized by HSP90 inhibition, overall resulting in a profound block of tumour growth. © Lippincott Williams & Wilkins.

Hanss D.,University of Geneva | Walther M.E.,University of Geneva | Wenger O.S.,University of Gottingen
Coordination Chemistry Reviews | Year: 2010

This review reports on our recent studies of phototriggered charge transfer in rigid rod-like donor-bridge-acceptor molecules in liquid solution as well as between randomly dispersed electron donors and acceptors in frozen organic glasses. Investigation of the distance dependence of the rates of these reactions provides detailed insight into the various factors that govern long-range charge transfer efficiencies. The importance of covalence can be probed by a comparison of charge tunneling through a frozen toluene matrix to tunneling across an oligo-p-xylene bridge. The distance decay constants for these two processes are β=1.26Å-1 and β=0.52Å-1, respectively, indicating that charge tunneling across a covalent xylene-xylene contact is ∼2 orders of magnitude more efficient than that across a noncovalent toluene-toluene contact. Conformational effects were investigated by comparing hole tunneling across oligo-p-xylene and oligo-p-phenylene bridges. The latter are significantly more π-conjugated and mediate long-range hole tunneling with β=0.21Å-1 between a ruthenium-phenothiazine donor-acceptor couple. Quantitative analysis indicates that in this particular instance, tunneling across a phenylene-phenylene contact is roughly 50 times more efficient than tunneling across a xylene-xylene contact. The use of oligo-p-dimethoxybenzene wires instead of the structurally very similar oligo-p-xylene bridges was found to lead to a strong acceleration of long-range hole transfer rates: The 23.5-Å charge transfer step across four xylene units occurs within 20μs, but the charge transfer over the same distance across four dimethoxybenzene units takes only 17ns. This is attributed to a tunneling-barrier effect that is caused by a large difference in oxidation potentials between the two types of bridges. © 2009 Elsevier B.V.

Vaseva A.V.,State University of New York at Stony Brook | Marchenko N.D.,State University of New York at Stony Brook | Ji K.,State University of New York at Stony Brook | Tsirka S.E.,State University of New York at Stony Brook | And 3 more authors.
Cell | Year: 2012

Ischemia-associated oxidative damage leading to necrosis is a major cause of catastrophic tissue loss, and elucidating its signaling mechanism is therefore of paramount importance. p53 is a central stress sensor responding to multiple insults, including oxidative stress to orchestrate apoptotic and autophagic cell death. Whether p53 can also activate oxidative stress-induced necrosis is, however, unknown. Here, we uncover a role for p53 in activating necrosis. In response to oxidative stress, p53 accumulates in the mitochondrial matrix and triggers mitochondrial permeability transition pore (PTP) opening and necrosis by physical interaction with the PTP regulator cyclophilin D (CypD). Intriguingly, a robust p53-CypD complex forms during brain ischemia/reperfusion injury. In contrast, reduction of p53 levels or cyclosporine A pretreatment of mice prevents this complex and is associated with effective stroke protection. Our study identifies the mitochondrial p53-CypD axis as an important contributor to oxidative stress-induced necrosis and implicates this axis in stroke pathology. © 2012 Elsevier Inc.

Heijman J.,University of Duisburg - Essen | Dewenter M.,University of Gottingen | El-Armouche A.,University of Gottingen | Dobrev D.,University of Duisburg - Essen
Journal of Molecular and Cellular Cardiology | Year: 2013

Protein phosphorylation is a major control mechanism of a wide range of physiological processes and plays an important role in cardiac pathophysiology. Serine/threonine protein phosphatases control the dephosphorylation of a variety of cardiac proteins, thereby fine-tuning cardiac electrophysiology and function. Specificity of protein phosphatases type-1 and type-2A is achieved by multiprotein complexes that target the catalytic subunits to specific subcellular domains. Here, we describe the composition, regulation and target substrates of serine/threonine phosphatases in the heart. In addition, we provide an overview of pharmacological tools and genetic models to study the role of cardiac phosphatases. Finally, we review the role of protein phosphatases in the diseased heart, particularly in ventricular arrhythmias and atrial fibrillation and discuss their role as potential therapeutic targets. © 2013.

Method and neuroprosthetic device for monitoring and suppression of pathological tremors in a user through the neurostimulation of the afferent pathways to the brain, which comprises wearable elements placed over the parts of the body affected by tremor, wherein said wearable elements (1) have sensors selected from bioelectric sensors (3) generating a bioelectrical signal characterization of tremor, biomechanical sensors (4) generating a biomechanical signal characterization of tremor and a combination thereof, a programmable electronic device (9) comprised of a control, acquisition and processing module of the characterization signals, and a signal generator for the afferent stimulation based on the bioelectrical, biomechanical or combination of both signal characterization and stimulation electrodes (8) which transmit the neuromodulation signals to the afferent pathways projecting into the central nervous system to modulate the activity of the neural structures responsible for tremor generation.

Kurganova I.,University of Gottingen | Lopes de Gerenyu V.,Russian Academy of Sciences | Six J.,ETH Zurich | Kuzyakov Y.,University of Gottingen
Global Change Biology | Year: 2014

The collapse of collective farming in Russia after 1990 and the subsequent economic crisis led to the abandonment of more than 45 million ha of arable lands (23% of the agricultural area). This was the most widespread and abrupt land use change in the 20th century in the northern hemisphere. The withdrawal of land area from cultivation led to several benefits including carbon (C) sequestration. Here, we provide a geographically complete and spatially detailed analysis of C sequestered in these abandoned lands. The average C accumulation rate in the upper 20 cm of mineral soil was 0.96 ± 0.08 Mg C ha-1 yr-1 for the first 20 years after abandonment and 0.19 ± 0.10 Mg C ha-1 yr-1 during the next 30 years of postagrogenic evolution and natural vegetation establishment. The amount of C sequestered over the period 1990-2009 accounts to 42.6 ± 3.8 Tg C per year. This C sequestration rate is equivalent to ca. 10% of the annual C sink in all Russian forests. Furthermore, it compensates all fire and postfire CO2 emissions in Russia and covers about 4% of the global CO2 release due to deforestation and other land use changes. Our assessment shows a significant mitigation of increasing atmospheric CO2 by prolonged C accumulation in Russian soils caused by collective farming collapse. © 2013 John Wiley & Sons Ltd.

Ferrie A.M.R.,National Research Council Canada | Mollers C.,University of Gottingen
Plant Cell, Tissue and Organ Culture | Year: 2011

The availability of a highly efficient and reliable microspore culture protocol for many Brassica species makes this system useful for studying basic and applied research questions. Microspores and microspore-derived embryos are ideal targets for modification by mutagenesis and transformation. Regenerated doubled haploid plants are widely used in breeding programs and in genetic studies. Furthermore, the Brassica microspore culture system allows the identification of genomic regions and genes involved in the microspore embryogenic response, spontaneous diploidization and direct embryo to plant conversion. This review summarizes current achievements and discusses future perspectives. © 2010 Her Majesty the Queen in Right of Canada.

Maass R.,University of Gottingen | Loffler J.F.,ETH Zurich
Advanced Functional Materials | Year: 2015

The future of metallic glasses as an advanced structural and functional material will to a great extent depend on the understanding and control of their mesoscopic flow defects called shear bands. These defects are sweet-and-sour; sweet because they mediate macroscopic plasticity at room temperature, and sour because they quickly promote failure. In the past decade, fundamental research generated great progress in characterizing the role that shear bands play during plastic deformation of disordered systems, including metallic glasses. Similar to those in many other materials, shear bands in metallic glasses are only active for a very short time, which directed research focus towards topological, structural, chemical, and thermal properties of formed, but inactive shear bands. In this paper, recent progress in directly characterizing the shear-band dynamics in situ during straining experiments is presented. Various shear-banding stages are outlined, including formation, propagation, and arrest, as well as shear-band creep and aging. The results are discussed in a more general context of disordered materials, concluding with a summarizing overview of time-scales involved in shear banding, and describing future research directions that may lead to controlled shear-band plasticity in metallic glasses. Dynamic properties of shear bands are a key element for the design of plastically stable bulk metallic glasses. In this Feature Article, recent progress on in situ characterization of shear-band dynamics is summarized. The aim is to provide a comprehensive understanding of shear-band initiation, propagation, arrest, creep, and aging, and how they determine the plastic flow behavior of bulk metallic glasses. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Berndt M.,Max Planck Institute of Molecular Cell Biology and Genetics | Lorenz M.,Max Planck Institute of Molecular Cell Biology and Genetics | Enderlein J.,University of Gottingen | Diez S.,Max Planck Institute of Molecular Cell Biology and Genetics
Nano Letters | Year: 2010

We present a novel fluorescence lifetime imaging microscopy technique to measure absolute positions of fluorescent molecules within 100 nm above a metalized surface based on distance-dependent fluorescence lifetime modulations. We apply this technique to fluorescently labeled microtubules as optical probes with various unlabeled proteins attached. By measuring the fluorescence lifetimes, we obtain the position of the microtubules and therefore determine the geometrical size of the attached proteins with nanometer precision. © 2010 American Chemical Society.

Irani E.,University of Gottingen | Chaudhuri P.,Heinrich Heine University Düsseldorf | Heussinger C.,University of Gottingen
Physical Review Letters | Year: 2014

Using numerical simulations, the rheological response of an athermal assembly of soft particles with tunable attractive interactions is studied in the vicinity of jamming. At small attractions, a fragile solid develops and a finite yield stress is measured. Moreover, the measured flow curves have unstable regimes, which lead to persistent shear banding. These features are rationalized by establishing a link between the rheology and the interparticle connectivity, which also provides a minimal model to describe the flow curves. © 2014 American Physical Society.

Speck T.,Heinrich Heine University Düsseldorf | Vink R.L.C.,University of Gottingen
Physical Review E - Statistical, Nonlinear, and Soft Matter Physics | Year: 2012

Theoretical models describing specific adhesion of membranes predict (for certain parameters) a macroscopic phase separation of bonds into adhesion domains. We show that this behavior is fundamentally altered if the membrane is pinned randomly due to, e.g., proteins that anchor the membrane to the cytoskeleton. Perturbations which locally restrict membrane height fluctuations induce quenched disorder of the random-field type. This rigorously prevents the formation of macroscopic adhesion domains following the Imry-Ma argument. Our prediction of random-field disorder follows from analytical calculations and is strikingly confirmed in large-scale Monte Carlo simulations. These simulations are based on an efficient composite Monte Carlo move, whereby membrane height and bond degrees of freedom are updated simultaneously in a single move. The application of this move should prove rewarding for other systems also. © 2012 American Physical Society.

Hager A.,Center for Sustainable Development | Dohrenbusch A.,University of Gottingen
Hydrological Processes | Year: 2011

Tropical cloud forests have received increasing attention because of their significance for freshwater supply. This study aimed to understand hydro-meteorological gradients in relation to spatial changes in forest structure in north-western Costa Rica. Seven climate stations (measuring rainfall, horizontal precipitation, throughfall, temperature and soil moisture) were installed along a 2·5 km transect between 1200 and 1500 m.a.s.l. on the Atlantic (windward) slope and the Pacific (leeward) slope of the Tilarán mountains. Forest structure was investigated on seven 10 × 50 m plots. Epiphytic vegetation was assessed on six trees at 1450 m and at 1200 m on the Pacific slope. Annual rainfall ranged from 3690 mm on the leeward slope to 6390 mm on the windward side. Horizontal precipitation was 3560 mm at the ridge, where it exceeded rainfall during the dry season, compared to 330 mm and 28 mm at the lowest windward and leeward plots, respectively. Throughfall remained below rainfall on the lower slopes but exceeded rainfall on the ridge. Soil water content ranged between 70% and 80% on the ridge top, where waterlogging occurred frequently. The studied forests were classified as lower montane rain forest, lower montane cloud forest and elfin cloud forest. The greatest canopy heights and basal areas occurred on the leeward slope between 1200 and 1450 m and at the lowest windward plot. Tree heights remained below 15 m on the ridge, where stilt roots occurred frequently. Near the ridge, epiphyte abundance and species richness were greater, compared to the lower leeward slope. These findings prove the importance of horizontal precipitation in the study area, confirm the important role of epiphytes as indicators for moisture gradients and elucidate the variability of forest structure under the given biophysical conditions. Copyright © 2010 John Wiley & Sons, Ltd.

Gruber O.,University of Gottingen | Santuccione A.C.,Roche Holding AG | Aach H.,Roche Holding AG
Frontiers in Psychiatry | Year: 2014

Schizophrenia is characterized by positive, negative, and cognitive symptoms. While positive symptoms occur periodically during psychotic exacerbations, negative and cognitive symptoms often emerge before the first psychotic episode and persist with low functional outcome and poor prognosis. This review article outlines the importance of modern functional magnetic resonance imaging techniques for developing a stratified therapy of schizophrenic disorders. Functional neuroimaging evidence on the neural correlates of positive and particularly negative symptoms and cognitive deficits in schizophrenic disorders is briefly reviewed. Acute dysregulation of dopaminergic neurotransmission is crucially involved in the occurrence of psychotic symptoms. However, increasing evidence also implicates glutamatergic pathomechanisms, in particular N-methyl-d-aspartate (NMDA) receptor dysfunction in the pathogenesis of schizophrenia and in the appearance of negative symptoms and cognitive dysfunctions. In line with this notion, several gene variants affecting the NMDA receptor's pathway have been reported to increase susceptibility for schizophrenia, and have been investigated using the imaging genetics approach. In recent years, several attempts have been made to develop medications modulating the glutamatergic pathway with modest evidences for efficacy. The most successful approaches were those that aimed at influencing this pathway using compounds that enhance NMDA receptor function. More recently, the selective glycine reuptake inhibitor bitopertin has been shown to improve NMDA receptor hypofunction by increasing glycine concentrations in the synaptic cleft. Further research is required to test whether pharmacological agents with effects on the glutamatergic system can help to improve the treatment of negative symptoms in schizophrenic disorders. © 2014 Gruber, Chadha Santuccione and Aach.

Wilkins B.J.,University of Gottingen | Rall N.A.,University of Gottingen | Ostwal Y.,Max Planck Institute for Biophysical Chemistry | Kruitwagen T.,ETH Zurich | And 5 more authors.
Science | Year: 2014

Metaphase chromosomes are visible hallmarks of mitosis, yet our understanding of their structure and of the forces shaping them is rudimentary. Phosphorylation of histone H3 serine 10 (H3 S10) by Aurora B kinase is a signature event of mitosis, but its function in chromatin condensation is unclear. Using genetically encoded ultraviolet light-inducible cross-linkers, we monitored protein-protein interactions with spatiotemporal resolution in living yeast to identify the molecular details of the pathway downstream of H3 S10 phosphorylation. This modification leads to the recruitment of the histone deacetylase Hst2p that subsequently removes an acetyl group from histone H4 lysine 16, freeing the H4 tail to interact with the surface of neighboring nucleosomes and promoting fiber condensation. This cascade of events provides a condensin-independent driving force of chromatin hypercondensation during mitosis.

Ellis E.C.,University of Maryland, Baltimore | Antill E.C.,University of Maryland, Baltimore | Kreft H.,University of Gottingen
PLoS ONE | Year: 2012

Anthropogenic global changes in biodiversity are generally portrayed in terms of massive native species losses or invasions caused by recent human disturbance. Yet these biodiversity changes and others caused directly by human populations and their use of land tend to co-occur as long-term biodiversity change processes in the Anthropocene. Here we explore contemporary anthropogenic global patterns in vascular plant species richness at regional landscape scales by combining spatially explicit models and estimates for native species loss together with gains in exotics caused by species invasions and the introduction of agricultural domesticates and ornamental exotic plants. The patterns thus derived confirm that while native losses are likely significant across at least half of Earth's ice-free land, model predictions indicate that plant species richness has increased overall in most regional landscapes, mostly because species invasions tend to exceed native losses. While global observing systems and models that integrate anthropogenic species loss, introduction and invasion at regional landscape scales remain at an early stage of development, integrating predictions from existing models within a single assessment confirms their vast global extent and significance while revealing novel patterns and their potential drivers. Effective global stewardship of plant biodiversity in the Anthropocene will require integrated frameworks for observing, modeling and forecasting the different forms of anthropogenic biodiversity change processes at regional landscape scales, towards conserving biodiversity within the novel plant communities created and sustained by human systems. © 2012 Ellis et al.

Konietschke F.,University of Gottingen | Pauly M.,Heinrich Heine University Düsseldorf
Statistics and Computing | Year: 2014

We study various bootstrap and permutation methods for matched pairs, whose distributions can have different shapes even under the null hypothesis of no treatment effect. Although the data may not be exchangeable under the null, we investigate different permutation approaches as valid procedures for finite sample sizes. It will be shown that permutation or bootstrap schemes, which neglect the dependency structure in the data, are asymptotically valid. Simulation studies show that these new tests improve the power of the t-test under non-normality. © 2013 The Author(s).

Schleicher D.R.G.,University of Gottingen | Miniati F.,ETH Zurich
Monthly Notices of the Royal Astronomical Society: Letters | Year: 2011

Primordial magnetic fields generated in the early Universe are subject of considerable investigation, and observational limits on their strength are required to constrain the theory. Due to their impact on the reionization process, the strength of primordial fields can be limited using the latest data on reionization and the observed UV luminosity function of high-redshift galaxies. Given the steep faint-end slope of the luminosity function, faint galaxies contribute substantial ionizing photons, and the low-luminosity cut-off has an impact on the total budget thereof. Magnetic pressure from primordial fields affects such cut-off by preventing collapse in haloes with mass below 1010M, with B0 the comoving field strength. In this Letter, the implications of these effects are consistently incorporated in a simplified model for reionization, and the uncertainties due to the cosmological parameters, the reionization parameters and the observed UV luminosity function are addressed. We show that the observed ionization degree at z~ 7 leads to the strongest upper limit of B0≲ 2-3nG. Stronger limits could follow from measurements of high ionization degree at z > 7. © 2011 The Authors Monthly Notices of the Royal Astronomical Society © 2011 RAS.

Latif M.A.,University Pierre and Marie Curie | Schleicher D.R.G.,University of Gottingen | Schleicher D.R.G.,Normal School of Pisa
Monthly Notices of the Royal Astronomical Society | Year: 2015

Our understanding of Population III star formation is still in its infancy. They are formed in dark matter minihaloes of 105-106M⊙ at z = 20-30. Recent high-resolution cosmological simulations show that a protostellar disc forms as a consequence of gravitational collapse and fragments into multiple clumps. However, it is not entirely clear if these clumps will be able to survive to form multiple stars as simulations are unable to follow the disc evolution for longer times. In this study, we employ a simple analytical model to derive the properties of marginally stable steady-state discs. Our results show that the stability of the disc depends on the critical value of the viscous parameter α. For αcrit = 1, the disc is stable for an accretion rate of ≤10-3M⊙ yr-1 and becomes unstable at radii about ≥100 au in the presence of an accretion rate of 10-2M⊙ yr-1. For 0.06 < αcrit < 1, the disc can be unstable for both accretion rates. The comparison of the migration and the Kelvin-Helmholtz time-scales shows that clumps are expected to migrate inwards before reaching the main sequence. Furthermore, in the presence of a massive central star, the clumps within the central 1 au will be tidally disrupted. We also find that UV feedback from the central star is unable to disrupt the disc, and that photoevaporation becomes important only once the accretion rate has dropped to 2 × 10-4M⊙ yr-1. As a result, the central star may reach a mass of 100 M⊙ or even higher. © 2015 The Authors.

Nickerson R.C.,San Francisco State University | Varshney U.,Georgia State University | Muntermann J.,University of Gottingen
European Journal of Information Systems | Year: 2013

A fundamental problem in many disciplines is the classification of objects in a domain of interest into a taxonomy. Developing a taxonomy, however, is a complex process that has not been adequately addressed in the information systems (IS) literature. The purpose of this paper is to present a method for taxonomy development that can be used in IS. First, this paper demonstrates through a comprehensive literature survey that taxonomy development in IS has largely been ad hoc. Then the paper defines the problem of taxonomy development. Next, the paper presents a method for taxonomy development that is based on taxonomy development literature in other disciplines and shows that the method has certain desirable qualities. Finally, the paper demonstrates the efficacy of the method by developing a taxonomy in a domain in IS. © 2013 Operational Research Society Ltd. All rights reserved.

Battefeld D.,University of Gottingen | Peter P.,University Pierre and Marie Curie
Physics Reports | Year: 2015

Given the proliferation of bouncing models in recent years, we gather and critically assess these proposals in a comprehensive review. The PLANCK data shows an unmistakably red, quasi scale-invariant, purely adiabatic primordial power spectrum and no primary non-Gaussianities. While these observations are consistent with inflationary predictions, bouncing cosmologies aspire to provide an alternative framework to explain them. Such models face many problems, both of the purely theoretical kind, such as the necessity of violating the NEC and instabilities, and at the cosmological application level, as exemplified by the possible presence of shear. We provide a pedagogical introduction to these problems and also assess the fitness of different proposals with respect to the data. For example, many models predict a slightly blue spectrum and must be fine-tuned to generate a red spectral index; as a side effect, large non-Gaussianities often result. We highlight several promising attempts to violate the NEC without introducing dangerous instabilities at the classical and/or quantum level. If primordial gravitational waves are observed, certain bouncing cosmologies, such as the cyclic scenario, are in trouble, while others remain valid. We conclude that, while most bouncing cosmologies are far from providing an alternative to the inflationary paradigm, a handful of interesting proposals have surfaced, which warrant further research. The constraints and lessons learned as laid out in this review might guide future research. © 2015 Published by Elsevier B.V.

Jousset A.,University of Gottingen | Schmid B.,University of Zürich | Scheu S.,University of Gottingen | Eisenhauer N.,University of Gottingen | Eisenhauer N.,University of Minnesota
Ecology Letters | Year: 2011

Biodiversity is an essential determinant of ecosystem functioning. Numerous studies described positive effects of diversity on the functioning of communities arising from complementary resource use and facilitation. However, high biodiversity may also increase competitive interactions, fostering antagonism and negatively affecting community performance. Using experimental bacterial communities we differentiated diversity effects based on genotypic richness and dissimilarity. We show that these diversity characteristics have opposite effects on ecosystem functioning. Genotypic dissimilarity governed complementary resource use, improving ecosystem functioning in complex resource environments. Contrastingly, genotypic richness drove allelopathic interactions, mostly reducing ecosystem functioning. The net biodiversity effect on community performance resulted from the interplay between the genetic structure of the community and resource complexity. These results demonstrate that increasing richness, without concomitantly increasing dissimilarity, can decrease ecosystem functioning in simple environments due to antagonistic interactions, an effect insufficiently considered so far in mechanistic models of the biodiversity-ecosystem functioning relationship. © 2011 Blackwell Publishing Ltd/CNRS.

Thoms S.,University of Gottingen | Harms I.,University of Lübeck | Kalies K.-U.,University of Lübeck | Gartner J.,University of Gottingen
Traffic | Year: 2012

In peroxisome formation, models of near-autonomous peroxisome biogenesis with membrane protein integration directly from the cytosol into the peroxisomal membrane are in direct conflict with models whereby peroxisomes bud from the endoplasmic reticulum and receive their membrane proteins through a branch of the secretory pathway. We therefore reinvestigated the role of the Sec61 complex, the protein-conducting channel of the endoplasmic reticulum (ER) in peroxisome formation. We found that depletion or partial inactivation of Sec61 in yeast disables peroxisome formation. The ER entry of the early peroxisomal membrane protein Pex3 engineered with a glycosylation tag is reduced in sec61 mutant cells. Moreover, we were able to reconstitute Pex3 import into ER membranes in vitro, and we identified a variant of a signal anchor sequence for ER translocation at the Pex3 N-terminus. Our findings are consistent with a Sec61 requirement for peroxisome formation and a fundamental role of the ER in peroxisome biogenesis. © 2011 John Wiley & Sons A/S.

Gagnevin D.,University College Dublin | Daly J.S.,University College Dublin | Kronz A.,University of Gottingen
Contributions to Mineralogy and Petrology | Year: 2010

This study documents the chemical and textural responses of zircon in the Elba igneous complex, with particular reference to the 7- to 7.8-Ma-old Monte Capanne pluton in relation to its coeval volcanic counterpart (Capraia), using BSE imaging and quantitative electron microprobe analyses. The Monte Capanne pluton displays multiple field and geochemical evidence for magma mixing. The samples we have investigated (including monzogranitic, mafic enclave and dyke samples) display similar zircon textures and are associated with an extremely large range of trace and minor element (Hf, Y, HREE, Th, U) compositions, which contrast with relatively simple textures and zoning patterns in zircons from a Capraia dacite. We have used a relatively simple textural classification (patchy zoning, homogenous cores, oscillatory zoning and unzoned zircon) as the basis for discussing the chemical composition and chemical variation within zircons from the Monte Capanne pluton. Based on these data and other works (Dini et al. 2004 in Lithos 78:101-118, 2004), it is inferred that mixing between metaluminous and peraluminous melts occurred early in the evolution of the Monte Capanne magma chamber. In particular, mixing was responsible for the development of the patchy-zoning texture in the zircon cores, which was associated with reactions between other accessory phases (including monazite, apatite, allanite), which we infer to have significantly affected the Th distribution in zircon. Zircons from the MC pluton displaying "homogeneous cores" have chemical affinities with zircons in the coeval Capraia volcanic system, consistent with the participation of a Capraia-like mantle end-member during mixing. Further zircon growth in the MC pluton produced the oscillatory zoning texture, which records both long-term (crystal fractionation) and transient (recharge with both silicic and mafic magmas) events in a hybrid magma chamber. It is inferred that Hf and the Th/U ratio cannot be used alone to infer magmatic processes due to their dependency on temperature, nor are they a diagnostic feature of xenocrystic grains. This study shows that zircon chemistry coupled with detailed textural analysis can provide a powerful tool to elucidate the complex evolution of a magma system. © 2009 Springer-Verlag.

Eisenhauer N.,University of Minnesota | Cesarz S.,University of Gottingen | Koller R.,University of Cologne | Worm K.,University of Minnesota | Reich P.B.,University of Minnesota
Global Change Biology | Year: 2012

The world's ecosystems are subjected to various anthropogenic global change agents, such as enrichment of atmospheric CO 2 concentrations, nitrogen (N) deposition, and changes in precipitation regimes. Despite the increasing appreciation that the consequences of impending global change can be better understood if varying agents are studied in concert, there is a paucity of multi-factor long-term studies, particularly on belowground processes. Herein, we address this gap by examining the responses of soil food webs and biodiversity to enrichment of CO 2, elevated N, and summer drought in a long-term grassland study at Cedar Creek, Minnesota, USA (BioCON experiment). We use structural equation modeling (SEM), various abiotic and biotic explanatory variables, and data on soil microorganisms, protozoa, nematodes, and soil microarthropods to identify the impacts of multiple global change effects on drivers belowground. We found that long-term (13-year) changes in CO 2 and N availability resulted in modest alterations of soil biotic food webs and biodiversity via several mechanisms, encompassing soil water availability, plant productivity, and - most importantly - changes in rhizodeposition. Four years of manipulation of summer drought exerted surprisingly minor effects, only detrimentally affecting belowground herbivores and ciliate protists at elevated N. Elevated CO 2 increased microbial biomass and the density of ciliates, microarthropod detritivores, and gamasid mites, most likely by fueling soil food webs with labile C. Moreover, beneficial bottom-up effects of elevated CO 2 compensated for detrimental elevated N effects on soil microarthropod taxa richness. In contrast, nematode taxa richness was lowest at elevated CO 2 and elevated N. Thus, enrichment of atmospheric CO 2 concentrations and N deposition may result in taxonomically and functionally altered, potentially simplified, soil communities. Detrimental effects of N deposition on soil biodiversity underscore recent reports on plant community simplification. This is of particular concern, as soils house a considerable fraction of global biodiversity and ecosystem functions. © 2011 Blackwell Publishing Ltd.

Meinhold G.,University of Gottingen | Morton A.C.,University of Cambridge | Morton A.C.,HM Research Associates | Avigad D.,Hebrew University of Jerusalem
Gondwana Research | Year: 2013

We present a synopsis of detrital zircon U-Pb ages of sandstones from North Africa and neighboring Israel and Jordan, which allows us to identify zones with characteristic sediment provenance along the northern Gondwana margin (in present-day coordinates) in Cambrian-Ordovician times, and helps us to unravel the peri-Gondwana jigsaw puzzle. A special feature of the early Paleozoic cover sequence of North Africa is the eastward increase of 1.1-0.95. Ga detrital zircons, which become ubiquitous in the early Paleozoic sandstones of the Saharan Metacraton. Detrital zircons aged about 2.7-2.5, 2.15-1.75 and 0.75-0.53. Ga are also present. Early Paleozoic sandstones with similar provenance are known from peri-Gondwana terranes in the Eastern and Western Mediterranean and from NW Iberia. These terranes need not be transported from western Gondwana (Amazonia) as suggested previously. They were likely located to the north of the Saharan Metacraton during the early Paleozoic before they rifted off from Gondwana. Furthermore, we recognize an increase, as stratigraphic ages get younger, of ca. 1.0. Ga detrital zircons at some point between the Late Cambrian and late Middle Ordovician. We speculate that this might be linked to far-field tectonics and regional uplift in central Gondwana related to plate-tectonic reorganization along the Gondwana margin, leading to erosion of ca. 1.0. Ga basement and country rocks of the Transgondwanan supermountain and fluvial dispersal of detritus toward the Gondwana margin. © 2012 International Association for Gondwana Research.

Rand T.A.,U.S. Department of Agriculture | van Veen F.J.F.,University of Exeter | Tscharntke T.,University of Gottingen
Ecography | Year: 2012

The differential loss of higher trophic levels in the face of natural habitat loss can result in the disruption of important trophic interactions, such as biological control. Natural enemies of herbivorous pests in cropping systems often benefit from the presence of natural habitats in surrounding landscapes, as they provide key resources such as alternative hosts. However, any benefits from a biological control perspective may be dampened if this also enhances enemies at the fourth trophic level. Remarkably, studies of the influence of landscape structure on diversity and interactions of fourth trophic-level natural enemies are largely lacking. We carried out a large-scale sampling study to investigate the effects of landscape complexity (i.e. the proportion of non-crop habitat in the landscapes surrounding focal study areas) on the parasitoid communities of aphids in wheat and on an abundant extra-field plant, stinging nettle. Primary parasitoid communities (3rd trophic level) attacking the cereal aphid, Sitobion avenae, had little overlap with the communities attacking the nettle aphid, Microlophium carnosum, while secondary parasitoids (4th trophic level) showed high levels of species overlap across these two aphids (25 vs 73% shared species respectively), resulting in significantly higher linkage density and lower specialization for secondary than primary parasitoid webs. In wheat, parasitoid diversity was not related to landscape complexity for either primary or secondary parasitoids. Rates of primary parasitism were generally low, while secondary parasitism rates were high (37-94%) and increased significantly with increasing landscape complexity, although this pattern was driven by a single secondary parasitoid species. Overall, our results demonstrate that extra-field habitats and landscape complexity can differentially benefit fourth, over third, trophic level natural enemies, and thereby, could dampen biological control. Our results further suggest that fourth trophic-level enemies may play an important, yet understudied, role in linking insect population dynamics across habitat types. © 2011 The Authors. Ecography © 2012 Nordic Society Oikos.

Herold M.J.,Walter and Eliza Hall Institute of Medical Research | Reichardt H.M.,University of Gottingen
Critical Reviews in Immunology | Year: 2013

Glucocorticoids (GCs) are highly potent anti-inflammatory and immunosuppressive agents. They exert influence on many cell types of the immune system and impact a plethora of processes such as cytokine production, leukocyte differentiation, migration and adhesion, apoptosis induction, and changes in morphology. Those that are most relevant for the modulation of neuroinflammatory diseases, however, are still under debate. In this review, we will elaborate on how GCs impact inflammatory responses in general and revisit the ambivalent role that apoptosis plays in animal models of multiple sclerosis. Furthermore, we will discuss arguments that speak in favor or against an essential function of GC-induced apoptosis in neuroinflammation. We anticipate that a better knowledge of the mechanisms that GCs employ will eventually find its way into clinical practice for the future benefit of afflicted patients. © 2013 by Begell House, Inc.

Han J.E.,State University of New York at Buffalo | Dirks A.,University of Gottingen | Pruschke T.,University of Gottingen
Physical Review B - Condensed Matter and Materials Physics | Year: 2012

We discuss the formal relationship between the real-time Keldysh and imaginary-time theory for nonequilibrium in quantum dot systems. The latter can be reformulated using the recently proposed Matsubara-voltage approach. We establish general conditions for correct analytic continuation procedure on physical observables, and apply the technique to the calculation of static quantities in steady-state nonequilibrium for a quantum dot subject to a finite bias voltage and external magnetic field. Limitations of the Matsubara voltage approach are also pointed out. © 2012 American Physical Society.

Leimbach A.,University of Munster | Leimbach A.,University of Gottingen | Hacker J.,German National Academy of science Leopoldina | Dobrindt U.,University of Munster
Current Topics in Microbiology and Immunology | Year: 2013

Escherichia coli is a paradigm for a versatile bacterial species which comprises harmless commensal as well as different pathogenic variants with the ability to either cause intestinal or extraintestinal diseases in humans and many animal hosts. Because of this broad spectrum of lifestyles and phenotypes, E. coli is a well-suited model organism to study bacterial evolution and adaptation to different growth conditions and niches. The geno- and phenotypic diversity, however, also hampers risk assessment and strain typing. A marked genome plasticity is the key to the great variability seen in this species. Acquisition of genetic information by horizontal gene transfer, gene loss as well as other genomic modifications, like DNA rearrangements and point mutations, can constantly alter the genome content and thus the fitness and competitiveness of individual variants in certain niches. Specific gene subsets and traits have been correlated with an increased potential of E. coli strains to cause intestinal or extraintestinal disease. Intestinal pathogenic E. coli strains can be reliably discriminated from non-pathogenic, commensal, or from extraintestinal E. coli pathogens based on genome content and phenotypic traits. An unambiguous distinction of extraintestinal pathogenic E. coli and commensals is, nevertheless, not so easy, as strains with the ability to cause extraintestinal infection are facultative pathogens and belong to the normal flora of many healthy individuals. Here, we compare insights into phylogeny, geno-, and phenotypic traits of commensal and pathogenic E. coli. We demonstrate that the borderline between extraintestinal virulence and intestinal fitness can be blurred as improved adaptability and competitiveness may promote intestinal colonization as well as extraintestinal infection by E. coli. © Springer-Verlag Berlin Heidelberg 2013.

Crane K.,California Institute of Technology | Weischedel C.,University of Gottingen | Wardetzky M.,University of Gottingen
ACM Transactions on Graphics | Year: 2013

We introduce the heat method for computing the geodesic distance to a specified subset (e.g., point or curve) of a given domain. The heat method is robust, efficient, and simple to implement since it is based on solving a pair of standard linear elliptic problems. The resulting systems can be prefactored once and subsequently solved in near-linear time. In practice, distance is updated an order of magnitude faster than with state-of-the-art methods, while maintaining a comparable level of accuracy. The method requires only standard differential operators and can hence be applied on a wide variety of domains (grids, triangle meshes, point clouds, etc.). We provide numerical evidence that the method converges to the exact distance in the limit of refinement; we also explore smoothed approximations of distance suitable for applications where greater regularity is required. © 2013 ACM.

Butenschoen O.,University of Gottingen | Scheu S.,University of Gottingen | Eisenhauer N.,University of Minnesota
Soil Biology and Biochemistry | Year: 2011

Human activity has induced a multitude of global changes that are likely to affect the functioning of ecosystems. Although these changes act in concert, studies on interactive effects are scarce. Here, we conducted a laboratory microcosm experiment to explore the impacts of temperature (9, 12 and 15 °C), changes in soil humidity (moist, dry) and plant diversity (1, 4, 16 species) on soil microbial activity and litter decomposition. We found that changes in litter decomposition did not mirror impacts on microbial measures indicating that the duration of the experiment (22 weeks) may not have been sufficient to determine the full magnitude of global change effects. However and notably, changes in temperature, humidity and plant litter diversity/composition affected in a non-additive way the microbial parameters investigated. For instance, microbial metabolic efficiency increased with plant diversity in the high moisture treatment but remained unaffected in low moisture treatment suggesting that climate changes may mask beneficial effects of biodiversity on ecosystem functioning. Moreover, litter decomposition was unaffected by plant litter diversity/composition but increased with increasing temperature in the high moisture treatment, and decreased with increasing temperature in the low moisture treatment. We conclude that it is inevitable to perform complex experiments considering multiple global change agents in order to realistically predict future changes in ecosystem functioning. Non-additive interactions highlight the context-dependency of impacts of single global change agents. © 2011 Elsevier Ltd.

Basri G.,University of California at Berkeley | Walkowicz L.M.,Princeton University | Reiners A.,University of Gottingen
Astrophysical Journal | Year: 2013

We utilize Kepler data to study the precision differential photometric variability of solar-type and cooler stars at different timescales, ranging from half an hour to three months. We define a diagnostic that characterizes the median differential intensity change between data bins of a given timescale. We apply the same diagnostics to Solar and Heliospheric Observatory data that has been rendered comparable to Kepler. The Sun exhibits similar photometric variability on all timescales as comparable solar-type stars in the Kepler field. The previously defined photometric "range" serves as our activity proxy (driven by starspot coverage). We revisit the fraction of comparable stars in the Kepler field that are more active than the Sun. The exact active fraction depends on what is meant by "more active than the Sun" and on the magnitude limit of the sample of stars considered. This active fraction is between a quarter and a third (depending on the timescale). We argue that a reliable result requires timescales of half a day or longer and stars brighter than MKep of 14, otherwise non-stellar noise distorts it. We also analyze main sequence stars grouped by temperature from 6500 to 3500 K. As one moves to cooler stars, the active fraction of stars becomes steadily larger (greater than 90% for early M dwarfs). The Sun is a good photometric model at all timescales for those cooler stars that have long-term variability within the span of solar variability. © 2013. The American Astronomical Society. All rights reserved.

Musa S.,Hebrew University of Jerusalem | Ackermann L.,University of Gottingen | Gelman D.,Hebrew University of Jerusalem
Advanced Synthesis and Catalysis | Year: 2013

Homo-and cross-coupling of alcohols resulting in the formation of the corresponding ketones in very good to excellent yield was realized through the one-pot sequence of dehydrogenation/ aldol condensation/hydrogenation accompanied by the release of molecular hydrogen. The dehydrogenation and hydrogenation steps are catalyzed by the previously reported ruthernium-and iridiumbased ligand-metal cooperating catalysts. © 2013 Wiley-VCH Verlag GmbH&Co. KGaA, Weinheim.

Becker J.,University of Gottingen | Eisenhauer N.,University of Minnesota | Scheu S.,University of Gottingen | Jousset A.,University of Gottingen
Ecology Letters | Year: 2012

Biodiversity is a major determinant of ecosystem functioning. Species-rich communities often use resources more efficiently thereby improving community performance. However, high competition within diverse communities may also reduce community functioning. We manipulated the genotypic diversity of Pseudomonas fluorescens communities, a plant mutualistic species inhibiting pathogens. We measured antagonistic interactions in vitro, and related these interactions to bacterial community productivity (root colonisation) and ecosystem service (host plant protection). Antagonistic interactions increased disproportionally with species richness. Mutual poisoning between competitors lead to a 'negative complementarity effect', causing a decrease in bacterial density by up to 98% in diverse communities and a complete loss of plant protection. The results emphasize that antagonistic interactions may determine community functioning and cause negative biodiversity-ecosystem functioning relationships. Interference competition may thus be an additional key for predicting the dynamics and performance of natural assemblages and needs to be implemented in future biodiversity models. © 2012 Blackwell Publishing Ltd/CNRS.

Ye L.,University of Minnesota | Ye L.,University of Gottingen | Zimmermann W.-H.,German Center for Cardiovascular Research | Garry D.J.,University of Minnesota | Zhang J.,University of Minnesota
Circulation Research | Year: 2013

Transplantation of engineered tissue patches containing either progenitor cells or cardiomyocytes for cardiac repair is emerging as an exciting treatment option for patients with postinfarction left ventricular remodeling. The beneficial effects may evolve directly from remuscularization or indirectly through paracrine mechanisms that mobilize and activate endogenous progenitor cells to promote neovascularization and remuscularization, inhibit apoptosis, and attenuate left ventricular dilatation and disease progression. Despite encouraging results, further improvements are necessary to enhance current tissue engineering concepts and techniques and to achieve clinical impact. Herein, we review several strategies for cardiac remuscularization and paracrine support that can induce cardiac repair and attenuate left ventricular dysfunction from both within and outside the myocardium. © 2013 American Heart Association, Inc.

Northumbria University, University of Gottingen and Deutsches Primatenzentrum Gmbh | Date: 2011-12-14

The invention relates to the novel use of gene markers in a method of predicting the risk of or diagnosing a subject to develop graft versus host reaction (GvHR) or graft versus host disease (GvHD). In other aspects the invention also relates to methods of monitoring the efficacy of treatment of GvHR or GvHD, and methods of screening a candidate substance for the treatment of GvHR or GvHD.

Teichert I.,Ruhr University Bochum | Nowrousian M.,Ruhr University Bochum | Poggeler S.,University of Gottingen | Kuck U.,Ruhr University Bochum
Advances in Genetics | Year: 2014

Filamentous fungi are excellent experimental systems due to their short life cycles as well as easy and safe manipulation in the laboratory. They form three-dimensional structures with numerous different cell types and have a long tradition as genetic model organisms used to unravel basic mechanisms underlying eukaryotic cell differentiation. The filamentous ascomycete Sordaria macrospora is a model system for sexual fruiting body (perithecia) formation. S. macrospora is homothallic, i.e., self-fertile, easily genetically tractable, and well suited for large-scale genomics, transcriptomics, and proteomics studies. Specific features of its life cycle and the availability of a developmental mutant library make it an excellent system for studying cellular differentiation at the molecular level. In this review, we focus on recent developments in identifying gene and protein regulatory networks governing perithecia formation. A number of tools have been developed to genetically analyze developmental mutants and dissect transcriptional profiles at different developmental stages. Protein interaction studies allowed us to identify a highly conserved eukaryotic multisubunit protein complex, the striatin-interacting phosphatase and kinase complex and its role in sexual development. We have further identified a number of proteins involved in chromatin remodeling and transcriptional regulation of fruiting body development. Furthermore, we review the involvement of metabolic processes from both primary and secondary metabolism, and the role of nutrient recycling by autophagy in perithecia formation. Our research has uncovered numerous players regulating multicellular development in S. macrospora. Future research will focus on mechanistically understanding how these players are orchestrated in this fungal model system. © 2014 Elsevier Inc.

Schmidt-Schweda S.,University of Gottingen | Ohler A.,University of Gottingen | Post H.,Medical University of Graz | Pieske B.,Medical University of Graz
Resuscitation | Year: 2013

Aim of the study: Hypothermia exerts profound protection from neurological damage and death after resuscitation from circulatory arrest. Its application during concomitant cardiogenic shock has been discussed controversially, and still hypothermia is used with reserve when haemodynamic parameters are impaired. On the other hand hypothermia improves force development in isolated human myocardium. Thus, we hypothesized that hypothermia could beneficially affect cardiac function in patients during cardiogenic shock. Methods: 14 Patients, admitted to Intensive Care Unit for cardiogenic shock under inotropic support, were enrolled and moderate hypothermia (33. °C) was induced for either one (n=5, short-term) or twenty-four (n=9, mid-term) hours. Results: 12 patients suffered from ischaemic cardiomyopathy, 2 were female, and 6 were included after cardiac arrest and resuscitation. Body temperature was controlled by an intravascular cooling device. Short-term hypothermia consistently decreased heart rate, and increased stroke volume, cardiac index and cardiac power output. Metabolic and electrocardiographic parameters remained constant during cooling. Improved cardiac function persisted during mid-term hypothermia, but was reversed during re-warming. No severe or persistent adverse effects of hypothermia were observed. Conclusion: Moderate Hypothermia is safe and feasable in patients during cardiogenic shock. Moreover, hypothermia improved parameters of cardiac function, suggesting that hypothermia might be considered as a positive inotropic intervention rather than a risk for patients during cardiogenic shock. © 2012 Elsevier Ireland Ltd.

Koster S.,University of Gottingen | Weitz D.A.,Harvard University | Goldman R.D.,Northwestern University | Aebi U.,University of Basel | Herrmann H.,German Cancer Research Center
Current Opinion in Cell Biology | Year: 2015

Intermediate filament proteins form filaments, fibers and networks both in the cytoplasm and the nucleus of metazoan cells. Their general structural building plan accommodates highly varying amino acid sequences to yield extended dimeric α-helical coiled coils of highly conserved design. These 'rod' particles are the basic building blocks of intrinsically flexible, filamentous structures that are able to resist high mechanical stresses, that is, bending and stretching to a considerable degree, both in vitro and in the cell. Biophysical and computer modeling studies are beginning to unfold detailed structural and mechanical insights into these major supramolecular assemblies of cell architecture, not only in the 'test tube' but also in the cellular and tissue context. © 2015 Elsevier Ltd.

Cakoni F.,University of Delaware | Kress R.,University of Gottingen
Inverse Problems | Year: 2013

Determining the shape of an inclusion within a conducting medium from voltage and current measurements on the accessible boundary of the medium can be modeled as an inverse boundary value problem for the Laplace equation. We present a solution method for such an inverse boundary value problem with a generalized impedance boundary condition on the inclusion via boundary integral equations. Both the determination of the unknown boundary and the determination of the unknown impedance functions are considered. In addition to describing the reconstruction algorithms and illustrating their feasibility by numerical examples, we also obtain a uniqueness result on determining the impedance coefficients. © 2013 IOP Publishing Ltd.

Frund J.,University of Gottingen | Dormann C.F.,Helmholtz Center for Environmental Research | Tscharntke T.,University of Gottingen
Ecology Letters | Year: 2011

Temporal patterns of flower opening and closure within a day are known as Linné's floral clock. Time of flower closure has been explained mainly by light in the traditional botanical literature. We show with a set of experiments that Asteraceae flower heads can close within three hours after pollination, whereas un-pollinated flower heads stay open until the late afternoon. This suggests that closing time strongly depends on pollinators. Using plant-pollinator interaction webs we further demonstrate that the daily pattern of flower opening and the rapid response to pollination can impose strong temporal dynamics on interspecific interactions within a single day. We observed pollinator species turnover and changes in facilitation vs. competition among plants. Our results show for the first time that pollination induces rapid flower closure on the community level. This causes imprecision in Linné's floral clock with far-reaching consequences for plant-pollinator interactions. © 2011 Blackwell Publishing Ltd/CNRS.

Albrecht S.C.,German Cancer Research Center | Barata A.G.,German Cancer Research Center | Grosshans J.,University of Gottingen | Teleman A.A.,German Cancer Research Center | Dick T.P.,German Cancer Research Center
Cell Metabolism | Year: 2011

The glutathione redox couple (GSH/GSSG) and hydrogen peroxide (H 2O 2) are central to redox homeostasis and redox signaling, yet their distribution within an organism is difficult to measure. Using genetically encoded redox probes in Drosophila, we establish quantitative in vivo mapping of the glutathione redox potential (E GSH) and H 2O 2 in defined subcellular compartments (cytosol and mitochondria) across the whole animal during development and aging. A chemical strategy to trap the in vivo redox state of the transgenic biosensor during specimen dissection and fixation expands the scope of fluorescence redox imaging to include the deep tissues of the adult fly. We find that development and aging are associated with redox changes that are distinctly redox couple-, subcellular compartment-, and tissue-specific. Midgut enterocytes are identified as prominent sites of age-dependent cytosolic H 2O 2 accumulation. A longer life span correlated with increased formation of oxidants in the gut, rather than a decrease. © 2011 Elsevier Inc.

Kiel S.,University of Gottingen | Kiel S.,University of Vienna
Proceedings of the Royal Society B: Biological Sciences | Year: 2015

The origin and evolution of the faunas inhabiting deep-sea hydrothermal vents andmethane seeps have been debated for decades. These faunas rely on a local source of sulfide and other reduced chemicals for nutrition, which spawned the hypothesis that their evolutionary history is independent from that of photosynthesis- based food chains and instead driven by extinction events caused by deep-sea anoxia. Here I use the fossil record of seep molluscs to show that trends in body size, relative abundance and epifaunal/infaunal ratios track current estimates of seawater sulfate concentrations through the last 150 Myr. Furthermore, the two main faunal turnovers during this time interval coincide with major changes in seawater sulfate concentrations. Because sulfide at seeps originates mostly from seawater sulfate, variations in sulfate concentrations should directly affect the base of the food chain of this ecosystem and are thus the likely driver of the observed macroecologic and evolutionary patterns. The results imply that the methane-seep fauna evolved largely independently from developments and mass extinctions affecting the photosynthesis-based biosphere and add to the growing body of evidence that the chemical evolution of the oceans had a major impact on the evolution of marine life. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

Voracek M.,University of Vienna | Voracek M.,University of Gottingen
Evolution and Human Behavior | Year: 2014

A series of meta-analyses assessed whether differentially efficacious variants (CAG and GGC repeat-length polymorphisms) of the human androgen receptor gene are associated with digit ratio (2D:4D), a widely investigated putative pointer to prenatal androgen action. Extensive literature search strategies identified a maximum of 18 samples (total N= 2909) vs. 5 samples (N= 1497) for the CAG-related vs. GGC-related meta-analyses, respectively. In contrast to a small-sample (N= 50) initial report, widely cited affirmatively in the literature, meta-analysis of the entire retrievable evidence base did not support any associations between CAG variants and right-hand, left-hand, or right-minus-left-hand 2D:4D. Effects of GGC variants on digit ratios likewise were almost exactly null. For the CAG literature, time trend analysis indicated shrinking effects among more recent studies. Both quantitative and qualitative citation analyses documented that citation bias exists in the research literature: CAG-related studies yielding larger effects were cited more frequently within the same time unit, and the initial, unreplicated report continued to be cited frequently and mostly solely as well as confirmatively, while non-replications were cited much less often. The meta-analytical null findings, along with several further strands of evidence consistent with these, undermine one validity claim for 2D:4D as a retrospective pointer to prenatal testosterone action. Discussed are alternative interpretations of the evidence and avenues for future research. © 2014 Elsevier Inc.

Saouane S.,University of Gottingen | Norman S.E.,Queen's University of Belfast | Hardacre C.,Queen's University of Belfast | Fabbiani F.P.A.,University of Gottingen
Chemical Science | Year: 2013

The solid-state polymorphism of the ionic liquid 1-butyl-3- methylimidazolium hexafluorophosphate, [bmim][PF6], has been investigated via low-temperature and high-pressure crystallisation experiments. The samples have been characterised by single-crystal X-ray diffraction, optical microscopy and Raman spectroscopy. The solid-state phase behaviour of the compound is confirmed and clarified with respect to previous phase diagrams. The structures of the previously reported γ-form, which essentially exhibits a G′T cation conformation, as well as those of the elusive β- and α-forms, are reported. Crystals of the β-phase are twinned and the structure is heavily disordered; the cation conformation in this form is predominantly TT, though significant contributions from other less frequently encountered conformers are also observed at low temperature and high pressure. The cation conformation in the α-form is GT; the presence of the G′T conformer at 193 K in this phase can be eliminated on cooling to 100 K. Whilst X-ray structural data are overall in good agreement with previous interpretations based on Raman and NMR studies, they also reveal a more subtle interplay of intermolecular interactions, which give rise to a wider range of conformers than previously considered. © 2013 The Royal Society of Chemistry.

Carminati A.,University of Gottingen | Vetterlein D.,Helmholtz Center for Environmental Research
Annals of Botany | Year: 2013

BackgroundIt is known that the soil near roots, the so-called rhizosphere, has physical and chemical properties different from those of the bulk soil. Rhizosphere properties are the result of several processes: root and soil shrinking/swelling during drying/wetting cycles, soil compaction by root growth, mucilage exuded by root caps, interaction of mucilage with soil particles, mucilage shrinking/swelling and mucilage biodegradation. These processes may lead to variable rhizosphere properties, i.e. The presence of air-filled gaps between soil and roots; water repellence in the rhizosphere caused by drying of mucilage around the soil particles; or water accumulation in the rhizosphere due to the high water-holding capacity of mucilage. The resulting properties are not constant in time but they change as a function of soil condition, root growth rate and mucilage age.ScopeWe consider such a variability as an expression of rhizosphere plasticity, which may be a strategy for plants to control which part of the root system will have a facilitated access to water and which roots will be disconnected from the soil, for instance by air-filled gaps or by rhizosphere hydrophobicity. To describe such a dualism, we suggest classifying rhizosphere into two categories: class A refers to a rhizosphere covered with hydrated mucilage that optimally connects roots to soil and facilitates water uptake from dry soils. Class B refers to the case of air-filled gaps and/or hydrophobic rhizosphere, which isolate roots from the soil and may limit water uptake from the soil as well water loss to the soil. The main function of roots covered by class B will be long-distance transport of water.OutlookThis concept has implications for soil and plant water relations at the plant scale. Root water uptake in dry conditions is expected to shift to regions covered with rhizosphere class A. On the other hand, hydraulic lift may be limited in regions covered with rhizosphere class B. New experimental methods need to be developed and applied to different plant species and soil types, in order to understand whether such dualism in rhizosphere properties is an important mechanism for efficient utilization of scarce resources and drought tolerance. © 2012 The Author.

Thiele J.C.,University of Gottingen | Grimm V.,Helmholtz Center for Environmental Research
Environmental Modelling and Software | Year: 2010

NetLogo is a software platform for agent-based modelling that is increasingly used in ecological and environmental modelling. So far, for comprehensive analyses of agent-based models (ABMs) implemented in NetLogo, results needed to be written to files and evaluated by using external software, for example R. Ideally, however, it would be possible to call any R function from within a NetLogo program. This would allow sophisticated interactive statistical analysis of model structure and dynamics, using R functions and packages for generating certain statistical distributions and experimental design, and for implementing complex descriptive submodels within ABMs. Here we present an R extension of NetLogo. It consists of only nine new NetLogo primitives for sending data between NetLogo and R and for calling R functions (six additional primitives for debugging). We demonstrate the usage of the R extension with three short examples. © 2010 Elsevier Ltd. All rights reserved.

Mann K.,Max Planck Institute of Biochemistry | Jackson D.J.,University of Gottingen
BMC Genomics | Year: 2014

Background:With a diversity of pigmented shell morphotypes governed by Mendelian patterns of inheritance, the common grove snail, Cepaea nemoralis, has served as a model for evolutionary biologists and population geneticists for decades. Surprisingly, the molecular mechanisms by which C. nemoralis generates this pigmented shelled diversity, and the degree of evolutionary conservation present between molluscan shell-forming proteomes, remain unknown.Results:Here, using next generation sequencing and high throughput proteomics, we identify and characterize the major proteinaceous components of the C. nemoralis shell, the first shell-proteome for a pulmonate mollusc. The recent availability of several marine molluscan shell-proteomes, and the dataset we report here, allow us to identify 59 evolutionarily conserved and novel shell-forming proteins. While the C. nemoralis dataset is dominated by proteins that share little to no similarity with proteins in public databases, almost half of it shares similarity with proteins present in other molluscan shells. In addition, we could not find any indication that a protein (or class of proteins) is directly associated with shell pigmentation in C. nemoralis. This is in contrast to the only other partially characterized molluscan-shell pigmentation mechanism employed by the tropical abalone Haliotis asinina.Conclusions:The unique pulmonate shell-forming proteome that we report here reveals an abundance of both mollusc-specific and pulmonate-specific proteins, suggesting that novel coding sequences, and/or the extensive divergence of these sequences from ancestral sequences, supported the innovation of new shell types within the Conchifera. In addition, we report here the first evidence that molluscs use independently evolved mechanisms to pigment their shells. This proteome provides a solid foundation from which further studies aimed at the functional characterization of these shell-forming proteins can be conducted. © 2014 Mann and Jackson; licensee BioMed Central Ltd.

Stein A.,University of Gottingen | Gerstner K.,Helmholtz Center for Environmental Research | Kreft H.,University of Gottingen
Ecology Letters | Year: 2014

Environmental heterogeneity is regarded as one of the most important factors governing species richness gradients. An increase in available niche space, provision of refuges and opportunities for isolation and divergent adaptation are thought to enhance species coexistence, persistence and diversification. However, the extent and generality of positive heterogeneity-richness relationships are still debated. Apart from widespread evidence supporting positive relationships, negative and hump-shaped relationships have also been reported. In a meta-analysis of 1148 data points from 192 studies worldwide, we examine the strength and direction of the relationship between spatial environmental heterogeneity and species richness of terrestrial plants and animals. We find that separate effects of heterogeneity in land cover, vegetation, climate, soil and topography are significantly positive, with vegetation and topographic heterogeneity showing particularly strong associations with species richness. The use of equal-area study units, spatial grain and spatial extent emerge as key factors influencing the strength of heterogeneity-richness relationships, highlighting the pervasive influence of spatial scale in heterogeneity-richness studies. We provide the first quantitative support for the generality of positive heterogeneity-richness relationships across heterogeneity components, habitat types, taxa and spatial scales from landscape to global extents, and identify specific needs for future comparative heterogeneity-richness research. © 2014 John Wiley & Sons Ltd/CNRS.

Krahmer F.,University of Gottingen | Ward R.,University of Texas at Austin
IEEE Transactions on Image Processing | Year: 2014

In many signal processing applications, one wishes to acquire images that are sparse in transform domains such as spatial finite differences or wavelets using frequency domain samples. For such applications, overwhelming empirical evidence suggests that superior image reconstruction can be obtained through variable density sampling strategies that concentrate on lower frequencies. The wavelet and Fourier transform domains are not incoherent because low-order wavelets and low-order frequencies are correlated, so compressive sensing theory does not immediately imply sampling strategies and reconstruction guarantees. In this paper, we turn to a more refined notion of coherence - the so-called local coherence - measuring for each sensing vector separately how correlated it is to the sparsity basis. For Fourier measurements and Haar wavelet sparsity, the local coherence can be controlled and bounded explicitly, so for matrices comprised of frequencies sampled from a suitable inverse square power-law density, we can prove the restricted isometry property with near-optimal embedding dimensions. Consequently, the variable-density sampling strategy we provide allows for image reconstructions that are stable to sparsity defects and robust to measurement noise. Our results cover both reconstruction by $\ell1-minimization and total variation minimization. The local coherence framework developed in this paper should be of independent interest, as it implies that for optimal sparse recovery results, it suffices to have bounded average coherence from sensing basis to sparsity basis - as opposed to bounded maximal coherence - as long as the sampling strategy is adapted accordingly. © 1992-2012 IEEE.

Ozener B.,Cumhuriyet University | Fink B.,University of Gottingen
Evolution and Human Behavior | Year: 2010

Deviations from perfect symmetry in paired traits of otherwise bilateral symmetrical organisms are thought to reflect developmental quality, especially the ability to resist environmental perturbations early in ontogeny. It is well established that poor environmental conditions increase developmental instability (DI) as reflected by measurements of fluctuating asymmetry. In humans, there is evidence that DI relates to numerous fitness components, and studies have found that perceptions of facial attractiveness for example are positively correlated with measurements of facial symmetry. Here we report the data on measurements of facial symmetry of 503 Turkish senior year high school students aged 17 to 18 years, of whom 133 males and 117 females were recruited from a slum district of Şentepe in Ankara (Group 1), and 131 males and 122 females from three high schools in wealthy central urban areas (Group 2). Digital images were used to assess the degree of facial asymmetry as measured from seven paired traits and calculated as a composite score. Facial asymmetry of participants in Group 1 (slum district) was significantly higher than that of participants in Group 2 (urban areas). Moreover, males in Group 1 were found to have higher facial asymmetry than females, while no sex difference was observed in Group 2. We conclude that poor living conditions have an influence on DI in humans, which manifests itself in the form of facial asymmetry, and that this might be particularly true for males. © 2010 Elsevier Inc.

Stuessy T.F.,University of Vienna | Horandl E.,University of Gottingen
Cladistics | Year: 2014

The review of paraphyly in botanical systematics by Schmidt-Lebuhn brings together a number of useful perspectives for the reader. It fails to offer new ideas, however, and it does not recognize the fallacies of strict cladistic classification, namely accepting only holophyletic groups, and insisting that sister groups have the same rank. The reason for adherence to these rules is to maintain the convenience of cladistic classification. While convenience in biological classification by itself is not necessarily bad, it becomes unacceptable when its use overshadows achieving a higher level of evolutionary (and phylogenetic) information content. Evolutionary divergence and reticulation are both significant parts of the evolutionary process that cannot be ignored in biological classification and that are necessary for high predictive quality. © The Willi Hennig Society 2013.

Ohanyan V.,Yerevan State University | Honecker A.,University of Gottingen
Physical Review B - Condensed Matter and Materials Physics | Year: 2012

We study a spin-1/2 model with triangular XXZ clusters on the orthogonal-dimer chain in the presence of an external magnetic field. First, we discuss the case where the triangular clusters are coupled via intermediate "classical" Ising spins. Diagonalization of the triangular XXZ clusters yields the exact ground states; finite-temperature properties are computed exactly by an additional transfer-matrix step. A detailed analysis reveals a large variety of ground states at magnetization M equal to fractions 0, 1/4, and 1/2 of the saturation magnetization M=1. Some of these ground states break translational symmetry spontaneously and give rise to doubling of the unit cell. In a second part, we present complementary numerical data for the spin-1/2 Heisenberg model on the orthogonal-dimer chain. We analyze several examples of T=0 magnetization curves, entropy as a function of temperature T and magnetic field, and the associated magnetic cooling rate. Comparison of the two models shows that in certain situations the simplified exactly solvable model yields a qualitatively or sometimes even quantitatively accurate description of the more challenging quantum model, including a case which may be relevant to experimental observations of an enhanced magnetocaloric effect in the two-dimensional compound SrCu 2(BO 3) 2. © 2012 American Physical Society.

Horandl E.,University of Gottingen | Emadzade K.,University of Vienna
Perspectives in Plant Ecology, Evolution and Systematics | Year: 2012

Evolutionary classification attempts to integrate information on shared ancestry, evolutionary process and phenetic information into the taxonomic concept. Here we exemplify this concept on the monophyletic, species-rich and cosmopolitan plant genus Ranunculus. Previous classifications have rendered almost all traditional sections as polyphyletic, and a modern revision based on phylogenetic principles was so far lacking. Maximum parsimony and Bayesian inference analysis of a combined nuclear (ITS of nrDNA) and plastid DNA dataset (matK/. trnK, and psbJ- petA) provided a phylogenetic framework for the genus with nine well-supported subclades. Neighbor Net analysis revealed a reticulate data structure within two subclades with frequent polyploidy and/or hybridization. Character evolution was studied by McClade reconstructions of morphological data mapped on to the molecular tree topology. Morphological characters show a mosaic-like distribution, but express several shared states congruent to molecular clades. A total evidence approach (TE) based on the combined morphological and molecular dataset suggests a subdivision of Ranunculus into a paraphyletic, temperate to arctic group of five subclades (subg. Auricomus), and a temperate to subtropical clade with four subclades (subg. Ranunculus). Infrageneric classification of two subgenera and 17 sections is based on both monophyly s.l. as evident from TE and a minimum of shared morphological characters. Six subclades have shared morphological or karyological features (sects. Auricomus, Flammula, Oreophili, Polyanthemos, Ranunculus, Thora, and Trisecti). One subclade was subdivided into three smaller clades according to morphological data (sects. Epirotes, Leucoranunculus, Ranuncella, Aconitifolii). In the case of reticulate evolution and uncertain ancestry we accept well-supported genetic clusters with shared morphological features, as revealed by Neighbor Net analysis (sections Batrachium, Hecatonia, Pseudadonis). Character evolution connected to ecological shifts characterizes the paraphyletic section Ranunculastrum, the holophyletic section Euromontani (sect. nov.), and the monotypic sect. Echinella. The information content of our classification is compared to alternative concepts. © 2012 Perspectives in Plant Ecology, Evolution and Systematics.

Wagner S.,University of Gottingen | Rokita A.G.,University of Gottingen | Rokita A.G.,University of Iowa | Anderson M.E.,University of Iowa | Maier L.S.,University of Gottingen
Antioxidants and Redox Signaling | Year: 2013

Significance: In heart failure (HF), contractile dysfunction and arrhythmias result from disturbed intracellular Ca handling. Activated stress kinases like cAMP-dependent protein kinase A (PKA), protein kinase C (PKC), and Ca/calmodulin-dependent protein kinase II (CaMKII), which are known to influence many Ca-regulatory proteins, are mechanistically involved. Recent Advances: Beside classical activation pathways, it is becoming increasingly evident that reactive oxygen species (ROS) can directly oxidize these kinases, leading to alternative activation. Since HF is associated with increased ROS generation, ROS-activated serine/threonine kinases may play a crucial role in the disturbance of cellular Ca homeostasis. Many of the previously described ROS effects on ion channels and transporters are possibly mediated by these stress kinases. For instance, ROS have been shown to oxidize and activate CaMKII, thereby increasing Na influx through voltage-gated Na channels, which can lead to intracellular Na accumulation and action potential prolongation. Consequently, Ca entry via activated NCX is favored, which together with ROS-induced dysfunction of the sarcoplasmic reticulum can lead to dramatic intracellular Ca accumulation, diminished contractility, and arrhythmias. Critical Issues: While low amounts of ROS may regulate kinase activity, excessive uncontrolled ROS production may lead to direct redox modification of Ca handling proteins. Therefore, depending on the source and amount of ROS generated, ROS could have very different effects on Ca-handling proteins. Future Directions: The discrimination between fine-tuned ROS signaling and unspecific ROS damage may be crucial for the understanding of heart failure development and important for the investigation of targeted treatment strategies. © 2013, Mary Ann Liebert, Inc.

Kiel S.,University of Gottingen | Amano K.,Joetsu University of Education
Journal of Paleontology | Year: 2013

Bathymodiolin mussels are a group of bivalves associated with deep-sea hydrothermal vents and other reducing deep-sea habitats, and they have a particularly rich early Cenozoic fossil record in western Washington State, U.S.A. Here we recognize six species from middle Eocene to latest Oligocene deep-water methane seep deposits in western Washington. Two of them are new: Vulcanidas? goederti from the middle Eocene Humptulips Formation and Bathymodiolus (sensu lato) satsopensis from the late Oligocene part of the Lincoln Creek Formation. Very similar to the latter but more elongate are specimens from the early Oligocene Jansen Creek Member of the Makah Formation and are identified as B. (s.l.) aff. satsopensis. Bathymodiolus (s.l.) inouei Amano and Jenkins, 2011 is reported from the Lincoln Creek Formation. Idas? olympicus Kiel and Goedert, 2007 was previously known from late Eocene to Oligocene whale and wood falls in western Washington and is here reported from Oligocene seep deposits of the Makah and Pysht Formations. Vulcanidas? goederti occurs at a seep deposit from a paleodepth possibly as great as 2000 m, suggesting that its living relative, Vulcanidas insolatus Cosel and Marshall, 2010, which lives at depths of only 150-500 m, is derived from a deep-water ancestor. The bathymodiolins in western Washington indicate that the group originated at least in the middle Eocene and underwent a first diversification in the late Eocene to Oligocene. Early ontogenetic shells of all fossil species investigated so far, including the middle Eocene Vulcanidas? goederti, reflect planktotrophic larval development indicating that this developmental mode is an ancestral trait of bathymodiolins.Copyright © 2013, The Paleontological Society.

Miao G.-X.,Massachusetts Institute of Technology | Munzenberg M.,University of Gottingen | Moodera J.S.,Massachusetts Institute of Technology
Reports on Progress in Physics | Year: 2011

The phenomenon of quantum tunneling, which was discovered almost a century ago, has led to many subsequent discoveries. One such discovery, spin polarized tunneling, was made 40 years ago by Robert Meservey and Paul Tedrow (Tedrow and Meservey 1971 Phys. Rev. Lett. 26 192), and it has resulted in many fundamental observations and opened up an entirely new field of study. Until the mid-1990s, this field developed at a steady, low rate, after which a huge increase in activity suddenly occurred as a result of the unraveling of successful spin tunneling between two ferromagnets. In the past 15 years, several thousands of papers related to spin polarized tunneling and transport have been published, making this topic one of the hottest areas in condensed matter physics from both fundamental science and applications viewpoints. Many review papers and book chapters have been written in the past decade on this subject. This paper is not exhaustive by any means; rather, the emphases are on recent progress, technological developments and informing the reader about the current direction in which this topic is moving. © 2011 IOP Publishing Ltd.

Larrea M.L.,EcoCiencia | Werner F.A.,University of Gottingen
Forest Ecology and Management | Year: 2010

Although vascular epiphytes contribute substantially to the biodiversity of tropical montane forests, it is unclear how their diversity and community composition is affected by forest alteration. We studied the response of vascular epiphyte assemblages to different intensities of land-use in a montane wet forest of northeastern Ecuador: (1) unmanaged mature forest; (2) mature forest with mid- and understorey opened for cattle grazing; and (3) isolated remnant trees in cattle pastures. The numbers of individuals and species of epiphytes per host tree did not differ significantly between land-use types, neither did total epiphyte species richness (n=30 trees). However, total species richness of pteridophytes was significantly lower on isolated remnant trees compared to unmanaged forest, whereas several taxa rich in xerotolerant species (Bromeliaceae, Orchidaceae, Piperaceae) exhibited the opposite trend. An analysis of floristic composition using ordination (NMS) and randomisation techniques (MRPP) showed that epiphyte assemblages on isolated remnant trees were significantly distinct from unmanaged forest while managed forest was intermediate between those two vegetation types. Ordination analysis further indicated reduced floristic heterogeneity in disturbed habitats. These results suggest considerable, rapid species turnover since land-use change 6 years prior to study, with pteridophytes being replaced by more xerotolerant taxa. We attribute this floristic turnover primarily to changes in microclimate towards higher levels of light and desiccation stress associated with forest disturbance. Our results support the notion that community composition offers a more sensitive indicator of human disturbance than species richness. © 2010 Elsevier B.V.

Fuhrmans M.,Zernike Institute for Advanced Materials | Fuhrmans M.,University of Gottingen | Marrink S.J.,Zernike Institute for Advanced Materials
Journal of the American Chemical Society | Year: 2012

Fusion peptides are moderately hydrophobic segments of viral and nonviral membrane fusion proteins that enable these proteins to fuse two closely apposed biological membranes. In vitro assays furthermore show that even isolated fusion peptides alone can support membrane fusion in model systems. In addition, the fusion peptides have a distinct effect on the phase diagram of lipid mixtures. Here, we present molecular dynamics simulations investigating the effect of a particular fusion peptide, the influenza hemagglutinin fusion peptide and some of its mutants, on the lipid phase diagram. We detect a systematic shift toward phases with more positive mean curvature in the presence of the peptides, as well as an occurrence of bicontinuous cubic phases, which indicates a stabilization of Gaussian curvature. The wild-type fusion peptide has a stronger effect on the phase behavior as compared to the mutants, which we relate to its boomerang shape. Our results point to a different role of fusion peptides than hitherto assumed, the stabilization of pores rather than stalks along the fusion pathway. © 2011 American Chemical Society.

Sung H.-W.,University of Gottingen | Spangenberg S.,University of Gottingen | Vogt N.,Max Planck Institute for Developmental Biology | Grosshans J.,University of Gottingen
Current Biology | Year: 2013

The cell number of the early Drosophila embryo is determined by exactly 13 rounds of synchronous nuclear divisions, allowing cellularization and formation of the embryonic epithelium [1]. The pause in G2 in cycle 14 is controlled by multiple pathways, such as activation of DNA repair checkpoint, progression through S phase, and inhibitory phosphorylation of Cdk1, involving the genes grapes, mei41, and wee1 [2-8]. In addition, degradation of maternal RNAs [9] and zygotic gene expression [10, 11] are involved. The zinc finger Vielfältig (Vfl) controls expression of many early zygotic genes [12, 13], including the mitotic inhibitor frühstart [14, 15]. The functional relationship of these pathways and the mechanism for triggering the cell-cycle pause have remained unclear. Here, we show that a novel single-nucleotide mutation in the 3′ UTR of the RNPII215 gene leads to a reduced number of nuclear divisions that is accompanied by premature transcription of early zygotic genes and cellularization. The reduced number of nuclear divisions in mutant embryos depends on the transcription factor Vfl and on zygotic gene expression, but not on grapes, the mitotic inhibitor Frühstart, and the nucleocytoplasmic ratio. We propose that activation of zygotic gene expression is the trigger that determines the timely and concerted cell-cycle pause and cellularization. © 2013 Elsevier Ltd All rights reserved.

Splivallo R.,University of Gottingen | Ottonello S.,University of Parma | Mello A.,CNR Plant Protection Institute | Karlovsky P.,University of Gottingen
New Phytologist | Year: 2011

Summary: Truffles (Tuber spp.) are symbiotic fungi that develop underground in association with plant roots. Food connoisseurs describe their scent as sensual, seductive and unique. These mysterious fungi, however, do not produce their aroma for the mere pleasure of humans. Truffle volatiles act as odorant cues for mammals and insects which are thus able to locate the precious fungi underground and spread their spores. They also freely diffuse in the soil and mediate interactions with microorganisms and plant roots, potentially regulating a complex molecular dialogue among soil fauna and flora. The aim of this review is to synthesize 30 yr of research on truffle volatiles, spanning fields of study from chemical ecology to aroma biosynthesis. Specific aspects of truffle volatile ecology and biology will be discussed, including which species have been studied so far and for what purpose, what ecological role has been demonstrated or speculated to exist for specific truffle volatiles, which volatiles are common or unique to certain species and what their biosynthetic route might be. Future challenges in truffle aroma research will also be addressed, focusing on how high-throughput post-genomic technologies may advance our understanding of truffle aroma biosynthesis and chemical ecology. © 2010 New Phytologist Trust.

Ecker O.,International Food Policy Research Institute | Qaim M.,University of Gottingen
World Development | Year: 2011

Widespread malnutrition in developing countries calls for appropriate strategies, presupposing good knowledge about nutritional impacts of policies. Little previous work has been carried out in this direction, especially with respect to micronutrients. We use representative household data from Malawi and develop a demand systems approach to estimate income and price elasticities of food demand and nutrient consumption. These estimates are applied for policy simulations. Given multiple nutritional deficiencies, income-related policies are better suited than price policies to improve nutrition. While consumer price subsidies for maize improve calorie and mineral consumption, they can worsen vitamin consumption in urban areas. © 2010 Elsevier Ltd.

Sulieman S.,University of Khartoum | Sulieman S.,University of Gottingen | Tran L.-S.P.,RIKEN
Critical Reviews in Biotechnology | Year: 2013

Symbiotic nitrogen fixation is tightly regulated by a range of fine processes at the nodule level, over which the host plant has overall control through the whole life of the plant. The operation of this control at the nodule level is not yet fully understood, but greater knowledge will ultimately lead to a better improvement of N2 fixation through the use of crop legumes and genetic engineering of crop plants for higher performance. It has been suggested that, nodule responses to the nutritional complexity of the rhizosphere environment involve a great deal of coordination of sensing and signal transduction. This regulation can be achieved through several mechanisms, including changes in carbon metabolism, oxygen supply and/or overproduction of reactive oxygen and nitrogen species. Recently, the cycling of amino acids observed between the plant and bacteroid fractions suggests a new and important regulatory mechanism involved in nodule responses. Most of the recent transcriptional findings are consistent with the earlier biochemical and physiological reports. Current research revealed unique advances for nodule metabolism, especially on the regulation of asparagine synthetase gene expression and the control of asparagine (ASN) to N2 fixing activity. A large amount of ASN is found accumulating in the root nodules of the symbiotic plants under restricted environments, such as drought, salinity and nutrient deficiency. Exceptionally, ASN phloem feeding has resulted in an increased concentration of the ASN amide in nodules followed by a remarkable decrease in nodule activity. In this review, recent progress concerning the possible role of ASN in whole-plant-based down-regulation of symbiotic N 2 fixation will be reviewed. © 2013 Informa Healthcare USA, Inc.

Stingl J.C.,University of Ulm | Stingl J.C.,Federal Institute for Drugs and Medical Devices BfArM | Brockmoller J.,University of Gottingen | Viviani R.,University of Ulm
Molecular Psychiatry | Year: 2013

Polymorphic drug-metabolizing enzymes (DMEs) are responsible for the metabolism of the majority of psychotropic drugs. By explaining a large portion of variability in individual drug metabolism, pharmacogenetics offers a diagnostic tool in the burgeoning era of personalized medicine. This review updates existing evidence on the influence of pharmacogenetic variants on drug exposure and discusses the rationale for genetic testing in the clinical context. Dose adjustments based on pharmacogenetic knowledge are the first step to translate pharmacogenetics into clinical practice. However, also clinical factors, such as the consequences on toxicity and therapeutic failure, must be considered to provide clinical recommendations and assess the cost-effectiveness of pharmacogenetic treatment strategies. DME polymorphisms are relevant not only for clinical pharmacology and practice but also for research in psychiatry and neuroscience. Several DMEs, above all the cytochrome P (CYP) enzymes, are expressed in the brain, where they may contribute to the local biochemical homeostasis. Of particular interest is the possibility of DMEs playing a physiological role through their action on endogenous substrates, which may underlie the reported associations between genetic polymorphisms and cognitive function, personality and vulnerability to mental disorders. Neuroimaging studies have recently presented evidence of an effect of the CYP2D6 polymorphism on basic brain function. This review summarizes evidence on the effect of DME polymorphisms on brain function that adds to the well-known effects of DME polymorphisms on pharmacokinetics in explaining the range of phenotypes that are relevant to psychiatric practice. © 2013 Macmillan Publishers Limited.

Hojsgaard D.H.,Northeast National University | Hojsgaard D.H.,University of Gottingen | Martinez E.J.,Northeast National University | Quarin C.L.,Northeast National University
New Phytologist | Year: 2013

Meiotic and apomictic reproductive pathways develop simultaneously in facultative aposporous species, and compete to form a seed as a final goal. This developmental competition was evaluated in tetraploid genotypes of Paspalum malacophyllum in order to understand the low level of sexuality in facultative apomictic populations. Cyto-embryology on ovules, flow cytometry on seeds and progeny tests by DNA fingerprinting were used to measure the relative incidence of each meiotic or apomictic pathway along four different stages of the plant's life cycle, namely the beginning and end of gametogenesis, seed formation and adult offspring. A high variation in the frequencies of sexual and apomictic pathways occurred at the first two stages. A trend of radical decline in realized sexuality was then observed. Sexual and apomictic seeds were produced, but the efficiency of the sexual pathway dropped drastically, and exclusively clonal offspring remained. Both reproductive pathways are unstable at the beginning of development, and only the apomictic one remains functional. Key factors reducing sexuality are the faster growth and parthenogenetic development in the aposporous pathway, and an (epi)genetically negative background related to the extensive gene de-regulation pattern responsible for apomixis. The effects of inbreeding depression during post-fertilization development may further decrease the frequency of effective sexuality. © 2012 New Phytologist Trust.

Ulrich S.,Instituut Lorentz for Theoretical Physics | Zippelius A.,University of Gottingen | Zippelius A.,Max Planck Institute for Dynamics and Self-Organization
Physical Review Letters | Year: 2012

A freely falling stream of weakly cohesive granular particles is modeled and analyzed with the help of event driven simulations and continuum hydrodynamics. The former show a breakup of the stream into droplets, whose size is measured as a function of cohesive energy. Extensional flow is an exact solution of the one-dimensional Navier-Stokes equation, corresponding to a strain rate, decaying like t -1 from its initial value, γ ̇0. Expanding around this basic state, we show that the flow is stable for short times, γ ̇0t≪1, whereas for long times, γ ̇0t≫1, perturbations of all wavelengths grow. The growth rate of a given wavelength depends on the instant of time when the fluctuation occurs, so that the observable patterns can vary considerably. © 2012 American Physical Society.

Stollenz M.,Texas A&M University | Meyer F.,University of Gottingen
Organometallics | Year: 2012

Since its first report in 1981, mesitylcopper has become an extremely popular and useful reagent, with many new applications emerging during the past decade. This review summarizes its structural and spectroscopic properties and gives a brief overview of the multitude of fascinating compounds and reactions that have been discovered by using mesitylcopper. Specifically, the role of mesitylcopper in synthesizing oligonuclear homo- and heteroleptic copper(I) frameworks, including biorelevant copper(I) complexes, and the application of mesitylcopper in stoichiometric and catalytic C-C and C-heteroatom bond-forming reactions and as a precursor for nanoparticles and intermetallic phases are covered. © 2012 American Chemical Society.

Johnsen S.A.,University of Hamburg | Johnsen S.A.,University of Gottingen
FEBS Letters | Year: 2012

The post-translational modification of histone proteins plays an important role in controlling cell fate by directing essentially all DNA-associated nuclear processes. Misregulation and mutation of histone modifying enzymes is a hallmark of tumorigenesis. However, how these different epigenetic modifications lead to tumor initiation and/or progression remains poorly understood. Recent studies have uncovered a potential tumor suppressor role for histone H2B monoubiquitination (H2Bub1). Like many other histone modifications, H2Bub1 has diverse functions and plays roles both in transcriptional activation and repression as well as in controlling mRNA processing and directing DNA repair processes. Notably, H2Bub1 has been linked to transcriptional elongation and is preferentially found in the transcribed region of active genes. Its activity is intimately connected to active transcription and the transcriptional elongation regulatory protein cyclin-dependent kinase-9 (CDK9) and the facilitates chromatin transcription (FACT) complex. This review provides an overview of the current understanding of H2Bub1 function in mammalian systems with a particular emphasis on its role in cancer and potential options for exploiting this knowledge for the treatment of cancer. © 2012 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.

Seifried D.,University of Hamburg | Banerjee R.,University of Hamburg | Schleicher D.,University of Gottingen
Monthly Notices of the Royal Astronomical Society | Year: 2014

The first supernova explosions are potentially relevant sources for the production of the first large-scale magnetic fields. For this reason, we present a set of high-resolution simulations studying the effect of supernova explosions on magnetized, primordial haloes. We focus on the evolution of an initially small-scale magnetic field formed during the collapse of the halo. We vary the degree of magnetization, the halo mass, and the amount of explosion energy in order to account for expected variations as well as to infer systematical dependences of the results on initial conditions. Our simulations suggest that core collapse supernovae with an explosion energy of 1051 erg and more violent pair instability supernovae with 1053 erg are able to disrupt haloes with masses up to about 106 and 107 M⊙, respectively. The peak of the magnetic field spectra shows a continuous shift towards smaller k-values, i.e. larger length scales, over time reaching values as low as k = 4. On small scales, the magnetic energy decreases at the cost of the energy on large scales resulting in a well-ordered magnetic field with a strength up to ̃10-8 G depending on the initial conditions. The coherence length of the magnetic field inferred from the spectra reaches values up to 250 pc in agreement with those obtained from autocorrelation functions. We find the coherence length to be as large as 50 per cent of the radius of the supernova bubble. Extrapolating this relation to later stages, we suggest that significantly strong magnetic fields with coherence lengths as large as 1.5 kpc could be created. We discuss possible implications of our results on processes like recollapse of the halo, first galaxy formation, and the magnetization of the intergalactic medium. © 2014 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society.

Gavara N.,U.S. National Institutes of Health | Chadwick R.S.,U.S. National Institutes of Health | Chadwick R.S.,University of Gottingen
Nature Nanotechnology | Year: 2012

The atomic force microscope can detect the mechanical fingerprints of normal and diseased cells at the single-cell level under physiological conditions. However, atomic force microscopy studies of cell mechanics are limited by the 'bottom effect' artefact that arises from the stiff substrates used to culture cells. Because cells adhered to substrates are very thin, this artefact makes cells appear stiffer than they really are. Here, we show an analytical correction that accounts for this artefact when conical tips are used for atomic force microscope measurements of thin samples. Our bottom effect cone correction (BECC) corrects the Sneddon's model, which is widely used to measure Young's modulus, E. Comparing the performance of BECC and Sneddon's model on thin polyacrylamide gels, we find that although Sneddon's model overestimates E, BECC yields E values that are thickness-independent and similar to those obtained on thick regions of the gel. The application of BECC to measurements on live adherent fibroblasts demonstrates a significant improvement on the estimation of their local mechanical properties. © 2012 Macmillan Publishers Limited. All rights reserved.

van Wyk M.,University of Bern | Pielecka-Fortuna J.,University of Gottingen | Lowel S.,University of Gottingen | Kleinlogel S.,University of Bern
PLoS Biology | Year: 2015

Photoreceptor degeneration is one of the most prevalent causes of blindness. Despite photoreceptor loss, the inner retina and central visual pathways remain intact over an extended time period, which has led to creative optogenetic approaches to restore light sensitivity in the surviving inner retina. The major drawbacks of all optogenetic tools recently developed and tested in mouse models are their low light sensitivity and lack of physiological compatibility. Here we introduce a next-generation optogenetic tool, Opto-mGluR6, designed for retinal ON-bipolar cells, which overcomes these limitations. We show that Opto-mGluR6, a chimeric protein consisting of the intracellular domains of the ON-bipolar cell–specific metabotropic glutamate receptor mGluR6 and the light-sensing domains of melanopsin, reliably recovers vision at the retinal, cortical, and behavioral levels under moderate daylight illumination. © 2015 van Wyk et al.

Mader U.,University of Greifswald | Schmeisky A.G.,University of Gottingen | Florez L.A.,University of Gottingen | Stulke J.,University of Gottingen
Nucleic Acids Research | Year: 2012

In the post-genomic era, most components of a cell are known and they can be quantified by large-scale functional genomics approaches. However, genome annotation is the bottleneck that hampers our understanding of living cells and organisms. Up-to-date functional annotation is of special importance for model organisms that provide a frame of reference for studies with other relevant organisms. We have generated a Wiki-type database for the Gram-positive model bacterium Bacillus subtilis, SubtiWiki ( This Wiki is centered around the individual genes and gene products of B. subtilis and provides information on each aspect of gene function and expression as well as protein activity and its control. SubtiWiki is accompanied by two companion databases SubtiPathways and SubtInteract that provide graphical representations of B. subtilis metabolism and its regulation and of protein-protein interactions, respectively. The diagrams of both databases are easily navigatable using the popular Google maps API, and they are extensively linked with the SubtiWiki gene pages. Moreover, each gene/gene product was assigned to one or more functional categories and transcription factor regulons. Pages for the specific categories and regulons provide a rapid overview of functionally related genes/proteins. Today, SubtiWiki can be regarded as one of the most complete inventories of knowledge on a living organism in one single resource. © The Author(s) 2011. Published by Oxford University Press.

Bayer M.,Humboldt University of Berlin | Sommer W.,Humboldt University of Berlin | Schacht A.,University of Gottingen
Psychophysiology | Year: 2012

Event-related potentials (ERPs) revealed effects of emotional meaning on word recognition at distinguishable processing stages, in rare cases even in the P1 time range. However, the boundary conditions of these effects, such as the roles of different levels of linguistic processing or the relative contributions of the emotional valence and arousal dimensions, remain to be fully understood. The present study addresses this issue by employing two tasks of different processing demands on words that orthogonally varied in their emotional valence and arousal. Effects of emotional valence in ERPs were evident from 100ms after word onset and showed a task-insensitive processing advantage for positive words. Early posterior negativity (EPN) effects to high-arousing words were limited to the lexical decision task, corroborating recent reports that suggested that perceptual processing as reflected in the EPN might not be as automatic as previously assumed. © 2012 Society for Psychophysiological Research.

Lehnik-Habrink M.,University of Gottingen | Lewis R.J.,Northumbria University | Mader U.,University of Greifswald | Stulke J.,University of Gottingen
Molecular Microbiology | Year: 2012

RNAprocessing and degradation are key processes in the control of transcript accumulation and thus in the control of gene expression. In Escherichia coli, the underlying mechanisms and components of RNA decay are well characterized. By contrast, Grampositive bacteria do not possess several important players of E. coli RNA degradation, most notably the essential enzyme RNase E. Recent research on the model Gram-positive organism, Bacillus subtilis, has identified the essential RNases J1 and Y as crucial enzymes in RNA degradation. While RNase J1 is the first bacterial exoribonuclease with 5'-to-3' processivity, RNase Y is the founding member of a novel class of endoribonucleases. Both RNase J1 and RNase Y have a broad impact on the stability of B. subtilis mRNAs; a depletion of either enzyme affects more than 25% of all mRNAs. RNases J1 and Y as well as RNase J2, the polynucleotide phosphorylase PNPase, the RNA helicase CshA and the glycolytic enzymes enolase and phosphofructokinase have been proposed to form a complex, the RNA degradosome of B. subtilis. This review presents a model, based on recent published data, of RNA degradation in B. subtilis. Degradation is initiated by RNase Y-dependent endonucleolytic cleavage, followed by processive exoribonucleolysis of the generated fragments both in 3'-to-5' and in 5'-to-3' directions. The implications of these findings for pathogenic Gram-positive bacteria are also discussed. © 2012 Blackwell Publishing Ltd.

Rellecke J.,Humboldt University of Berlin | Sommer W.,Humboldt University of Berlin | Schacht A.,University of Gottingen
Brain Topography | Year: 2013

We investigated whether face-specific processes as indicated by the N170 in event-related brain potentials (ERPs) are modulated by emotional significance in facial expressions. Results yielded that emotional modulations over temporo-occipital electrodes typically used to measure the N170 were less pronounced when ERPs were referred to mastoids than when average reference was applied. This offers a potential explanation as to why the literature has so far yielded conflicting evidence regarding effects of emotional facial expressions on the N170. However, spatial distributions of the N170 and emotion effects across the scalp were distinguishable for the same time point, suggesting different neural sources for the N170 and emotion processing. We conclude that the N170 component itself is unaffected by emotional facial expressions, with overlapping activity from the emotion-sensitive early posterior negativity accounting for amplitude modulations over typical N170 electrodes. Our findings are consistent with traditional models of face processing assuming face and emotion encoding to be parallel and independent processes. © 2012 Springer Science+Business Media New York.

Zhu R.,University of Gottingen | Lubben J.,University of Gottingen | Dittrich B.,University of Hamburg | Clever G.H.,University of Gottingen
Angewandte Chemie - International Edition | Year: 2015

A simple self-assembled [Pd2L4] coordination cage consisting of four carbazole-based ligands was found to dimerize into the interpenetrated double cage [3X@Pd4L8] upon the addition of 1.5 equivalents of halide anions (X = Cl-, Br-). The halide anions serve as templates, as they are sandwiched by four PdII cations and occupy the three pockets of the entangled cage structure. The subsequent addition of larger amounts of the same halide triggers another structural conversion, now yielding a triply catenated link structure in which each PdII node is trans-coordinated by two pyridine donors and two halide ligands. This simple system demonstrates how molecular complexity can increase upon a gradual change of the relative concentrations of reaction partners that are able to serve different structural roles. © 2015 Wiley-VCH Verlag GmbH & Co. KGaA.

Richter D.W.,University of Gottingen | Richter D.W.,U.S. National Institutes of Health | Smith J.C.,University of Gottingen | Smith J.C.,U.S. National Institutes of Health
Physiology | Year: 2014

The cellular and circuit mechanisms generating the rhythm of breathing in mammals have been under intense investigation for decades. Here, we try to integrate the key discoveries into an updated description of the basic neural processes generating respiratory rhythm under in vivo conditions. © 2014 Int. Union Physiol. Sci./Am. Physiol. Soc.

Newbery D.M.,University of Bern | Van Der Burgt X.M.,University of Bern | Worbes M.,University of Gottingen | Chuyong G.B.,University of Buea
Ecological Monographs | Year: 2013

The large-crowned emergent tree Microberlinia bisulcata dominates rain forest groves at Korup National Park, Cameroon, along with two codominants, Tetraberlinia bifoliolata and T. korupensis. M. bisulcata has a pronounced modal size frequency distribution around ;110 cm stem diameter: its recruitment potential is very poor. It is a long-lived lightdemanding species, one of many found in African forests. Tetraberlinia species lack modality, are more shade tolerant, and recruit better. All three species are ectomycorrhizal. M. bisulcata dominates grove basal area, even though it has similar numbers of trees (≥50 cm stem diameter) as each of the other two species. This situation presented a conundrum that prompted a long-term study of grove dynamics. Enumerations of two plots (82.5 and 56.25 ha) between 1990 and 2010 showed mortality and recruitment of M. bisulcata to be very low (both rates ;0.2% per year) compared with Tetraberlinia (2.4% and 0.8% per year), and M. bisulcata grows twice as fast as the Tetraberlinia. Ordinations indicated that these three species determined community structure by their strong negative associations while other species showed almost none. Ranked species abundance curves fitted the Zipf-Mandelbrot model well and allowed "overdominance" of M. bisulcata to be estimated. Spatial analysis indicated strong repulsion by clusters of large (50 to >100 cm) and very large (≥100 cm) M. bisulcata of their own medium-sized (10 to >50 cm) trees and all sizes of Tetraberlinia. This was interpreted as competition by M. bisulcata increasing its dominance, but also inhibition of its own replacement potential. Stem coring showed a modal age of ̃200 years for M. bisulcata, but with large size variation (50-150 cm). Fifty-year model projections suggested little change in medium, decreases in large, and increases in very large trees of M. bisulcata, accompanied by overall decreases in medium and large trees of Tetraberlinia species. Realistically increasing very-large-tree mortality led to grove collapse without short-term replacement. M. bisulcata most likely depends on climatic events to rebuild its stands: the ratio of disturbance interval to median species' longevity is important. A new theory of transient dominance explains how M. bisulcata may be cycling in abundance over time and displaying nonequilibrium dynamics. © 2013 by the Ecological Society of America.

Donmez G.,Tufts University | Outeiro T.F.,University of Gottingen
EMBO Molecular Medicine | Year: 2013

Sirtuins are NAD-dependent protein deacetylases known to have protective effects against age-related diseases such as cancer, diabetes, cardiovascular and neurodegenerative diseases. In mammals, there are seven sirtuins (SIRT1-7), which display diversity in subcellular localization and function. While SIRT1 has been extensively investigated due to its initial connection with lifespan extension and involvement in calorie restriction, important biological and therapeutic roles of other sirtuins have only recently been recognized. Here, we review the potential roles and effects of SIRT1 and SIRT2 in neurodegenerative diseases. We discuss different functions and targets of SIRT1 and SIRT2 in a variety of neurodegenerative diseases including Alzheimer's disease (AD), Parkinson's disease (PD) and Huntington's Disease (HD). We also cover the role of SIRT1 in neuronal differentiation due to the possible implications in neurodegenerative conditions, and conclude with an outlook on the potential therapeutic value of SIRT1 and SIRT2 in these disorders. Sirtuins (SIRTs) are NAD-dependent protein deacetylases, which have been implicated in age-related diseases. This review discusses recent findings on the roles of SIRT1 and SIRT2 in neurodegenerative diseases and in potential therapeutic approaches. © 2013 The Authors. Published by John Wiley and Sons, Ltd on behalf of EMBO.

Timmermann A.,Helios Klinikum Emil von Behring | Timmermann A.,University of Gottingen
Anaesthesia | Year: 2011

Supraglottic airway devices (SAD) play an important role in the management of patients with difficult airways. Unlike other alternatives to standard tracheal intubation, e.g. videolaryngoscopy or intubation stylets, they enable ventilation even in patients with difficult facemask ventilation and simultaneous use as a conduit for tracheal intubation. Insertion is usually atraumatic, their use is familiar from elective anaesthesia, and compared with tracheal intubation is easier to learn for users with limited experienced in airway management. Use of SADs during difficult airway management is widely recommended in many guidelines for the operating room and in the pre-hospital setting. Despite numerous studies comparing different SADs in manikins, there are few randomised controlled trials comparing different SADs in patients with difficult airways. Therefore, most safety data come from extended use rather than high quality evidence and claims of efficacy and particularly safety must be interpreted cautiously. © 2011 The Association of Anaesthetists of Great Britain and Ireland.

Polania R.,University of Gottingen | Polania R.,University of Zürich | Nitsche M.A.,University of Gottingen | Korman C.,University of Gottingen | And 2 more authors.
Current Biology | Year: 2012

Functional cortical circuits for central executive functions have been shown to emerge by theta (∼6 Hz) phase-coupling of distant cortical areas [1-3]. It has been repeatedly shown that frontoparietal theta coupling at ∼0° relative phase is associated with recognition, encoding, short-term retention, and planning [1, 4, 5]; however, a causal link has not been demonstrated so far. Here we used transcranial alternating current stimulation [6-8] simultaneously applied at 6 Hz over left prefrontal and parietal cortices with a relative 0° ("synchronized" condition) or 180° ("desynchronized" condition) phase difference or a placebo stimulation condition, whereas healthy subjects performed a delayed letter discrimination task. We show that exogenously induced frontoparietal theta synchronization significantly improves visual memory-matching reaction times as compared to placebo stimulation. In contrast, exogenously induced frontoparietal theta desynchronization deteriorates performance. The present findings provide for the first time evidence of causality of theta phase-coupling of distant cortical areas for cognitive performance in healthy humans. Moreover, the results demonstrate the suitability of transcranial alternating current stimulation to artificially induce coupling or decoupling of behaviorally relevant brain rhythms between segregated cortical regions. © 2012 Elsevier Ltd.

Schneider F.,Humboldt University of Berlin | Gradmann D.,University of Gottingen | Hegemann P.,Humboldt University of Berlin
Biophysical Journal | Year: 2013

Channelrhodopsins are light-gated ion channels of green algae. They are widely used for the analysis of neuronal networks using light in the emerging field of optogenetics. Under steady-state light conditions, the two open states, O1 and O2, mediate the photocurrents with different ion conductance and selectivity. To understand the conducting process as well as its optogenetic applications, it is important to study ion binding and transport of this promiscuous cation channel. Here, we present an enzyme kinetic algorithm that allowed us to calculate the ion composition of the initial and steady-state photocurrents for multication media. The approach is based on current-voltage relations determined for the individual ions H+, Na+, Ca2+, and Mg2+. We identify and quantify the widely different competition of the ions in wild-type channelrhodopsin-2 and two high-performing channelrhodopsin variants CatCh+ and C1V1. Both variants show enhanced Ca2+ conductance, but only CatCh+ displays high steady-state Ca2+ currents at neutral pH due to reduced H+ competition and low inactivation. We demonstrate that for optogenetic applications, one should always take into account that the variable equilibria of the two open states depend on light intensity, voltage, and the ionic composition of the medium. © 2013 Biophysical Society.

Langenbruch C.,University of Gottingen | Helfrich M.,Johann Heinrich Von Thunen Institute | Flessa H.,Johann Heinrich Von Thunen Institute
Plant and Soil | Year: 2012

Aims: We aimed to determine the influence of the distribution of different broadleaved tree species on soil chemical properties in a mature deciduous forest in Central Germany. Methods: Triangles of three neighboring trees (tree clusters) that consisted of either one or two species of European beech (Fagus sylvatica L.), European ash (Fraxinus excelsior L.) or lime (Tilia cordata Mill. or Tilia platyphyllos Scop.) were selected and analyzed for their litterfall chemistry and chemical properties of the forest floor and mineral soil (0-10 cm and 10-20 cm). Results: Base saturation, pH-value and the stock of exchangeable Mg 2+ (0-10 cm) were highest under ash and lowest under beech. The proportion of exchangeable Al 3+ was smallest under ash and highest under beech. The stock of exchangeable Mg 2+ and Ca 2+ correlated positively with the annual input of the respective nutrient from leaf litterfall. Ash leaf litterfall contained highest amounts of Mg and Ca. Beech leaf litterfall showed the highest C:N ratio and lignin:N ratio. Soil pH, stocks of organic C, total N and exchangeable Mg 2+ and Ca 2+ correlated positively with increasing proportions of ash leaf litter to total leaf litterfall. Conclusions: Our results indicate that the abundance of ash in beech dominated forests on loess over limestone had a positive effect on soil chemical properties and reduced soil acidification. The intermixture and distribution of ash in beech-dominated stands resulted in an increase of the horizontal and vertical diversity of the soil habitat. © 2011 The Author(s).

Zeisberg M.,University of Gottingen | Kalluri R.,University of Houston
Clinical Journal of the American Society of Nephrology | Year: 2015

Long overlooked as the virtual compartment and then strictly characterized through descriptive morphologic analysis, the renal interstitium has finally been associated with function. With identification of interstitial reninand erythropoietin-producing cells, the most prominent endocrine functions of the kidney have now been attributed to the renal interstitium. This article reviews the functional role of renal interstitium. © 2015 by the American Society of Nephrology.

Siewert I.,University of Gottingen | Gale zowska J.,Wroclaw Medical University
Chemistry - A European Journal | Year: 2015

Herein, we report the synthesis, the thermochemical data, and the catalytic reactivity of a new mononuclear cobalt complex, which has four NH protons in the ligand sphere. The combination of the redox-active metal ion and NH units enabled the coupling of proton and electron-transfer steps, which we exploited in the electrocatalytic water oxidation. © 2015 Wiley-VCH Verlag GmbH & Co. KGaA.

Sivis M.,University of Gottingen | Duwe M.,University of Gottingen | Abel B.,Leibniz Institute of Surface Modification | Ropers C.,University of Gottingen
Nature Physics | Year: 2013

Strong-field phenomena in optical nanostructures have enabled the integration of nanophotonics, plasmonics and attosecond spectroscopy. For example, tremendous excitement was sparked by reports of nanostructure-enhanced high-harmonic generation. However, there is growing tension between the great promise held by extreme-ultraviolet and attosecond-pulse generation on the nanoscale, and the lack of successful implementations. Here, we address this problem in a study of highly nonlinear optical processes in gas-exposed bow-tie nanoantennas. We find multiphoton- and strong-field-induced atomic excitation and ionization resulting in extreme-ultraviolet fluorescence, as well as third- and fifth-harmonic generation intrinsic to the nanostructures. Identifying the intensity-dependent spectral fingerprint of atomic fluorescence, we gauge local plasmonic fields. Whereas intensities sufficient for high-harmonic generation are indeed achieved in the near-field, the nanoscopic volume is found to prohibit an efficient conversion. Our results illustrate opportunities and challenges in highly nonlinear plasmonics and its extension to the extreme ultraviolet. © 2013 Macmillan Publishers Limited. All rights reserved.

Ebers M.,University of Cologne | Maurer I.,University of Gottingen
Research Policy | Year: 2014

While research has produced ample evidence showing that absorptive capacity affects innovation and organizational performance outcomes, we still know little about why some organizations possess greater absorptive capacity than others. This study extends previous research by showing how absorptive capacity emerges as an unintended consequence from organizational boundary spanners' external and internal relational embeddedness and their relational empowerment. Drawing upon survey data from 218 inter-organizational projects in the German engineering industry, we propose and find empirically that potential and realized absorptive capacity have partially distinct antecedents. Moreover, we show that the two components of absorptive capacity unfold not only separate but also complementary effects on innovation, implying that the whole of absorptive capacity is greater than its parts. In examining how different components of absorptive capacity emerge and unfold their effects, this study addresses critical limitations of the literature on absorptive capacity. © 2013 Elsevier B.V. All rights reserved.

Furuya S.,Leibniz University of Hanover | Klaus M.,Leibniz University of Hanover | Nitsche M.A.,University of Gottingen | Paulus W.,University of Gottingen | Altenmuller E.,Leibniz University of Hanover
Journal of Neuroscience | Year: 2014

The roles of the motor cortex in the acquisition and performance of skilled finger movements have been extensively investigated over decades. Yet it is still not known whether these roles of motor cortex are expertise-dependent. The present study addresses this issue by comparing the effects of noninvasive transcranial direction current stimulation (tDCS) on the fine control of sequential finger movements in highly trained pianists and musically untrained individuals. Thirteen pianists and 13 untrained controls performed timed-sequence finger movements with each of the right and left hands before and after receiving bilateral tDCS over the primary motor cortices. The results demonstrate an improvement of fine motor control in both hands in musically untrained controls, but deterioration in pianists following anodal tDCS over the contralateral cortex and cathodal tDCS over the ipsilateral cortex compared with the sham stimulation. However, this change in motor performance was not evident after stimulating with the opposite montage. These findings support the notion that changes in dexterous finger movements induced by bihemispheric tDCS are expertise-dependent. ©2014 the authors.

Lehneck R.,University of Gottingen | Elleuche S.,TU Hamburg - Harburg | Poggeler S.,University of Gottingen
Molecular Microbiology | Year: 2014

Summary: The rapid interconversion of carbon dioxide and bicarbonate (hydrogen carbonate) is catalysed by metalloenzymes termed carbonic anhydrases (CAs). CAs have been identified in all three domains of life and can be divided into five evolutionarily unrelated classes (α, β, γ, δ andζ) that do not share significant sequence similarities. The function of the mammalian, prokaryotic and plant α-CAs has been intensively studied but the function of CAs in filamentous ascomycetes is mostly unknown. The filamentous ascomycete Sordaria macrospora codes for four CAs, three of the β-class and one of the α-class. Here, we present a functional analysis of CAS4, the S. macrospora α-class CA. The CAS4 protein was post-translationally glycosylated and secreted. The knockout strain Δcas4 had a significantly reduced rate of ascospore germination. To determine the cas genes required for S.macrospora growth under ambient air conditions, we constructed double and triple mutations of the four cas genes in all possible combinations and a quadruple mutant. Vegetative growth rate of the quadruple mutant lacking all cas genes was drastically reduced compared to the wild type and invaded the agar under normal air conditions. Likewise the fruiting bodies were embedded in the agar and completely devoid of mature ascospores. © 2014 John Wiley & Sons Ltd.

Trenkwalder C.,Paracelsus Elena Hospital | Paulus W.,University of Gottingen
Nature Reviews Neurology | Year: 2010

Restless legs syndrome (RLS) is a somatosensory network disorder that is clinically diagnosed according to four main criteria: an urge to move the legs, usually associated with unpleasant leg sensations; induction or exacerbation of symptoms by rest; symptom relief on activity; and diurnal fluctuations in symptoms with worsening in the evening and at night. Genetic variants in four chromosomal regions have been identified that increase the risk of RLS. In addition, various different lesions, ranging from peripheral neuropathies to spinal cord lesions or alterations of brain metabolism, are implicated in RLS. In most cases, sleep disorders with frequent sleep fragmentation and characteristic periodic limb movements during sleep can be identified during a polysomnographic recording. The first-line drugs for RLS are dopaminergic agents, which are effective in low to moderate doses. Alternative or additional treatments include opioids and anticonvulsants. Augmentationparadoxical worsening of symptoms by dopaminergic treatmentis the main problem encountered in difficult-to-treat patients. Iron deficiency must be identified and treated by supplementation, both to improve RLS symptoms and to potentially lower the risk of augmentation. Here, we review the latest studies pertaining to the pathophysiology, clinical presentation and management of RLS. © 2010 Macmillan Publishers Limited. All rights reserved.

Schaffelhofer S.,German Primate Center | Agudelo-Toro A.,German Primate Center | Scherberger H.,German Primate Center | Scherberger H.,University of Gottingen
Journal of Neuroscience | Year: 2015

Despite recent advances in decoding cortical activity for motor control, the development of hand prosthetics remains a major challenge. To reduce the complexity of such applications, higher cortical areas that also represent motor plans rather than just the individual movements might be advantageous. We investigated the decoding of many grip types using spiking activity from the anterior intraparietal (AIP), ventral premotor (F5), and primary motor (M1) cortices.Tworhesus monkeys were trained to grasp 50 objects in a delayed task while hand kinematics and spiking activity from six implanted electrode arrays (total of 192 electrodes) were recorded. Offline, we determined 20 grip types from the kinematic data and decoded these hand configurations and the grasped objects with a simple Bayesian classifier. When decoding from AIP, F5, and M1 combined, the mean accuracy was 50% (using planning activity) and 62% (during motor execution) for predicting the 50 objects (chance level, 2%) and substantially larger when predicting the 20 grip types (planning, 74%; execution, 86%; chance level, 5%). When decoding from individual arrays, objects and grip types could be predicted well during movement planning from AIP (medial array) and F5 (lateral array), whereas M1 predictions were poor. In contrast, predictions during movement execution were best from M1, whereas F5 performed only slightly worse. These results demonstrate for the first time that a large number of grip types can be decoded from higher cortical areas during movement preparation and execution, which could be relevant for future neuroprosthetic devices that decode motor plans. © 2015 the authors.

Alexa M.,TU Berlin | Wardetzky M.,University of Gottingen
ACM Transactions on Graphics | Year: 2011

While the theory and applications of discrete Laplacians on triangulated surfaces are well developed, far less is known about the general polygonal case. We present here a principled approach for constructing geometric discrete Laplacians on surfaces with arbitrary polygonal faces, encompassing non-planar and non-convex polygons. Our construction is guided by closely mimicking structural properties of the smooth Laplace-Beltrami operator. Among other features, our construction leads to an extension of the widely employed cotan formula from triangles to polygons. Besides carefully laying out theoretical aspects, we demonstrate the versatility of our approach for a variety of geometry processing applications, embarking on situations that would have been more difficult to achieve based on geometric Laplacians for simplicial meshes or purely combinatorial Laplacians for general meshes. © 2011 ACM.

Kozuch J.,TU Berlin | Steinem C.,University of Gottingen | Hildebrandt P.,TU Berlin | Millo D.,VU University Amsterdam
Angewandte Chemie - International Edition | Year: 2012

Support from the support: Tethered bilayer lipid membranes containing the cation-channel-forming peptide gramicidin A were assembled on nanostructured Au films. The combination of surface-enhanced infrared absorption (SEIRA) and electrochemical impedance spectroscopy (EIS) was used for the in situ structural and functional characterization of gramicidin A in the same device. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Harding D.J.,University of Gottingen | Harding D.J.,Max Planck Institute for Chemistry | Fielicke A.,TU Berlin
Chemistry - A European Journal | Year: 2014

Transition-metal clusters have long been proposed as model systems to study heterogeneous catalysts. In this Concept article we show how advanced spectroscopic techniques can be used to determine the structures of gas-phase transition-metal clusters and their complexes with small molecules. Combined with computational studies, this can help to develop an understanding of the reactivity of these catalytic models. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Tokiwa Y.,University of Gottingen | Bauer E.D.,Los Alamos National Laboratory | Gegenwart P.,University of Gottingen
Physical Review Letters | Year: 2013

Quantum criticality in the normal and superconducting states of the heavy-fermion metal CeCoIn5 is studied by measurements of the magnetic Grüneisen ratio ΓH and specific heat in different field orientations and temperatures down to 50 mK. A universal temperature over magnetic field scaling of ΓH in the normal state indicates a hidden quantum critical point at zero field. Within the superconducting state, the quasiparticle entropy at constant temperature increases upon reducing the field towards zero, providing additional evidence for zero-field quantum criticality. © 2013 American Physical Society.

Wagner H.,University of Gottingen | Bedorf D.,University of Gottingen | Kuchemann S.,University of Gottingen | Schwabe M.,University of Gottingen | And 4 more authors.
Nature Materials | Year: 2011

The nature of non-crystalline materials causes the local potential energy of a cluster of atoms or molecules to vary significantly in space. Different configurations of an ensemble of atoms in a metallic glass lead therefore to a distribution of elastic constants which also changes in space. This is totally different to their crystalline counterparts, where a long-range order exists in space and therefore a much more unified elastic modulus is expected. Using atomic force acoustic microscopy, we present data which show that the local so-called indentation modulus M indeed exhibits a wide distribution on a scale below 10 nm in amorphous PdCuSi, with ΔM/M≈30%. About 104 atoms are probed in an individual measurement. Crystallized PdCuSi shows a variation that is 10-30 times smaller and which is determined by the resolution of the microscope and by the polycrystalline structure of the material. © 2011 Macmillan Publishers Limited. All rights reserved.

Trautmann E.,University of Gottingen | Trautmann E.,Paracelsus Elena Hospital | Kroner-Herwig B.,University of Gottingen
Behaviour Research and Therapy | Year: 2010

Two different self-help training programs (multimodal cognitive-behavioral training (CBT) and applied relaxation (AR)) presented via the Internet were compared with an educational intervention (EDU) in an RCT. Sixty-five children and adolescents (mean age: 12.7 years) with recurrent headache (at least 2 attacks per month) were each assigned to one of the three treatment conditions. The main outcome variables related to changes in headache frequency, intensity and duration as well as the responder rate (50% reduction of headache frequency) and NNTs. Secondary outcome variables were pain catastrophizing and general well-being (depression, psychopathological symptoms and health-related quality of life). All groups showed significant reduction in headache frequency, duration and pain catastrophizing, but not in headache intensity, depression, psychopathological symptoms or health-related quality of life at post-assessment. NNTs were 2.0 for the comparison CBT and EDU; 5.2 for the comparison of AR and EDU at post-treatment. The highest responder rates at post were from CBT (63%), significantly different compared to AR (32%) and EDU (19%), whereas at follow-up no significant differences were found (CBT: 63%, AR: 56%, EDU: 55%) reflecting in the NNTs. The effects remain stable in headache frequency, pain catastrophizing and psychopathological symptoms across all groups at follow-up assessment. CBT showed the highest within-effect size in headache frequency, duration and pain catastrophizing. The results support the use of Internet programs for pediatric recurrent headache, especially given their accessibility and suitability for children and adolescents. Further studies are needed to improve their quality and efficacy. © 2009 Elsevier Ltd. All rights reserved.

Furuya S.,Leibniz University of Hanover | Nitsche M.A.,University of Gottingen | Paulus W.,University of Gottingen | Altenmuller E.,Leibniz University of Hanover
Annals of Neurology | Year: 2014

Objective Abnormal cortical excitability is evident in various movement disorders that compromise fine motor control. Here we tested whether skilled finger movements can be restored in musicians with focal hand dystonia through behavioral training assisted by transcranial direct current stimulation to the motor cortex of both hemispheres. Methods The bilateral motor cortices of 20 pianists (10 with focal dystonia, 10 healthy controls) were electrically stimulated noninvasively during bimanual mirrored finger movements. Results We found improvement in the rhythmic accuracy of sequential finger movements with the affected hand during and after cathodal stimulation over the affected cortex and simultaneous anodal stimulation over the unaffected cortex. The improvement was retained 4 days after intervention. Neither a stimulation with the reversed montage of electrodes nor sham stimulation yielded any improvement. Furthermore, the amount of improvement was positively correlated with the severity of the symptoms. Bihemispheric stimulation without concurrent motor training failed to improve fine motor control, underlining the importance of combined retraining and stimulation for restoring the dystonic symptoms. For the healthy pianists, none of the stimulation protocols enhanced movement accuracy. Interpretation These results suggest a therapeutic potential of behavioral training assisted by bihemispheric, noninvasive brain stimulation in restoring fine motor control in focal dystonia. © 2014 American Neurological Association.

Tokiwa Y.,University of Gottingen | Bauer E.D.,Los Alamos National Laboratory | Gegenwart P.,University of Gottingen
Physical Review Letters | Year: 2012

The heavy-fermion superconductor CeCoIn 5 displays an additional transition within its superconducting (SC) state, whose nature is characterized by high-precision studies of the isothermal field dependence of the entropy, derived from combined specific heat and magnetocaloric effect measurements at temperatures T100mK and fields H≤12T aligned along different directions. For any of these conditions, we do not observe an additional entropy contribution upon tuning at constant temperature by magnetic field from the homogeneous SC into the presumed Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) SC state. By contrast, for [100] a reduction of entropy was found that quantitatively agrees with the expectation for spin-density-wave order without FFLO superconductivity. Our data exclude the formation of a FFLO state in CeCoIn 5 for out-of-plane field directions, where no spin-density-wave order exists. © 2012 American Physical Society.

Klintschar M.,Leibniz University of Hanover | Heimbold C.,Leibniz University of Hanover | Heimbold C.,University of Gottingen
Pediatrics | Year: 2012

OBJECTIVES: Abnormalities in the serotonergic as well as the noradrenergic neuronal systems are believed to contribute to sudden infant death syndrome (SIDS). The X-chromosomal monoamine oxidase A (MAOA) gene is of importance for both systems and up to now no systematic study on a functional polymorphism in this gene has been performed in a sufficiently large group. METHODS: We investigated a functional MAOA promoter length polymorphism in 156 white SIDS cases and 260 gender- and age-matched control subjects by using capillary electrophoresis and fluorescence dye labeled primers. RESULTS: The pooled low-expressing alleles*2 and*3 were more frequent in the 99 male SIDS cases than in 161 male control subjects (44.4% vs 25.5%). However, there were no differences in female cases. The frequency of low expression alleles varied significantly with the age at death and were significantly more frequent in children who died between an age of 46 and 154 days than at an older age (54.9% vs 22.6%). CONCLUSIONS: Our results indicate a relationship between SIDS and the MAOA genotype in boys via influencing serotonergic and noradrenergic neurons in the brainstem. This locus is the first X-chromosomal locus associated with SIDS. Our results support the theory that abnormalities in the brainstem contribute to a subset of SIDS, at least in boys. Moreover, we argue that not only the serotonergic system but also other neuronal systems, among those the noradrenergic one, are involved. Copyright © 2012 by the American Academy of Pediatrics.

Zeisberg M.,University of Gottingen | Kalluri R.,University of Houston
American Journal of Physiology - Cell Physiology | Year: 2013

Fibrosis is a pathological scarring process that leads to destruction of organ architecture and impairment of organ function. Chronic loss of organ function in most organs, including bone marrow, heart, intestine, kidney, liver, lung, and skin, is associated with fibrosis, contributing to an estimated one third of natural deaths worldwide. Effective therapies to prevent or to even reverse existing fibrotic lesions are not yet available in any organ. There is hope that an understanding of common fibrosis pathways will lead to development of antifibrotic therapies that are effective in all of these tissues in the future. Here we review common and organ-specific pathways of tissue fibrosis. © 2013 the American Physiological Society.

Plomann M.,University of Cologne | Wittmann J.G.,University of Gottingen | Rudolph M.G.,University of Gottingen
Journal of Molecular Biology | Year: 2010

The protein kinase C and casein kinase 2 substrates in neurons (PACSINs) represent a subfamily of membrane-binding proteins characterized by an amino-terminal Bin-Amphiphysin-Rvs (F-BAR) domain. PACSINs link membrane trafficking with actin dynamics and regulate the localization of distinct cargo molecules. The F-BAR domain forms a dimer essential for lipid binding. We have obtained crystals of authentic murine PACSIN 2 that contain an ordered F-BAR domain, indicating that additional domains are flexibly connected to F-BAR. The structure shares similarity to other BAR domains and exhibits special features unique to PACSINs. These include the uneven distribution of charged residues on the concave molecular surface and a so-called wedge loop that is driven into the membrane upon binding of PACSIN. The murine PACSIN 2 F-BAR domain requires dimerization for sensing of curved membranes, and the present structure also provides a mechanism for higher-order oligomer formation. Importantly, comparison of murine with human and Drosophila PACSIN 2 F-BAR domains reveals stark differences in the orientation of distal helical segments leading to a wider crescent shape of murine PACSIN 2. We define hinge residues for these movements that may help PACSINs sense and concomitantly reinforce membrane curvature. © 2010 Elsevier Ltd.

Spork A.P.,University of Gottingen | Ducho C.,University of Gottingen
Organic and Biomolecular Chemistry | Year: 2010

Naturally occurring nucleoside antibiotics such as muraymycins represent promising lead structures for the development of novel antibacterial agents. A concise synthesis of 5′-deoxy muraymycin derivatives has been developed. The key step was the highly stereoselective asymmetric hydrogenation of suitable didehydro amino acid precursors, providing unique nucleosyl amino acid structures. © 2010 The Royal Society of Chemistry.

Sivis M.,University of Gottingen | Ropers C.,University of Gottingen
Physical Review Letters | Year: 2013

We present a study of the highly nonlinear optical excitation of noble gases in tapered hollow waveguides using few-femtosecond laser pulses. The local plasmonic field enhancement induces the generation of a nanometric plasma, resulting in incoherent extreme-ultraviolet fluorescence from optical transitions of neutral and ionized xenon, argon, and neon. Despite sufficient intensity in the waveguide, high-order harmonic generation is not observed. The fluorescent emission exhibits a strong bistability manifest as an intensity hysteresis, giving strong indications for multistep collisional excitations. © 2013 American Physical Society.

Kroner-Herwig B.,University of Gottingen | Gassmann J.,University of Gottingen
Headache | Year: 2012

Objective.-This cross-sectional study on a randomly drawn population sample of children and adolescents (n = 3399; aged 9 to 15) aimed at the assessment of patterns of associations between psychosocial variables and primary headache disorders like migraine (MIG) or tension-type headache. A headache-free group served as a control. Methods.-Data on headache and psychological trait variables (eg, internalizing symptoms), behavioral factors (eg, physical activities), and socio-environmental factors (eg, life events) were gathered by questionnaire. Logistic regression analyses were conducted with headache types (MIG, tension-type, and non-classifiable headache) as dependent variables. Results.-The pattern of correlations was largely congruent between the headache disorders. Associations were closest regarding maladaptive psychological traits (in particular internalizing symptoms with an odds ratio > 4 regarding MIG) compared with socio-environmental factors and particularly the behavioral factors. Unfavorable psychological traits and socio-environmental strains demonstrated distinctly stronger associations with MIG than tension-type headache and explained more variance in the occurrence of pediatric headache disorders than parental headache. Sex-specific analyses showed similarities as well as differences regarding the correlations, and in general, the associations were stronger in girls than boys. Conclusions.-A common path model as posited by several researchers in the field may explain the parallelism in biopsychosocial vulnerability regarding the different headache disorders. © 2012 American Headache Society.

Hauck M.,University of Gottingen | Lkhagvadorj D.,Mongolian State University of Agriculture
Ecological Indicators | Year: 2013

The ecological impact of the traditional land use by pastoral nomads on forest ecosystems is little studied. We analyzed the influence of livestock density on epiphytic lichen diversity in larch forests of the Mongolian forest-steppe, which we selected as a case example because pastoral nomadism is here most widespread within Central Asia. Canonical correspondence analysis showed that the epiphytic lichen vegetation was strongly influenced by the livestock density within a radius of 1 km around the sampled forests. Goats together with horses were most significant at shaping lichen vegetation in the forest edges as were horses alone in the forest interiors. This result matches with the results of interviews with 169 herder families and own field observations, which substantiate that goats preferably graze at the edges, whereas horses often browse the interiors. The livestock impact is thought to be primarily exerted through fertilization by the animals and mechanical abrasion. Based on an indicator species analyses, we propose to use epiphytic lichens as indicators of the grazing impact at different livestock densities in the Mongolian forest-steppe. The proposed indication system can be used as a tool for the rapid assessment of the livestock grazing impact. It has the advantage that it is thought to average the livestock impact of several years, which is important with regard to the nomadic style of livestock husbandry. The use of lichens as indicator species can at least partly substitute the time-consuming interviewing of the herder families to assess livestock densities and their impact on forest biodiversity. The proposed indicator system could thus be used as a planning tool for purposes of nature conservation. © 2013 Elsevier Ltd.

Weigelt P.,University of Gottingen | Jetz W.,Yale University | Kreft H.,University of Gottingen
Proceedings of the National Academy of Sciences of the United States of America | Year: 2013

The Earth's islands harbor a distinct, yet highly threatened, biological and cultural diversity that has been shaped by geographic isolation and unique environments. Island systems are key natural laboratories for testing theory in ecology and evolution. However, despite their potential usefulness for research, a quantitative description of island environments and an environmental classification are still lacking. Here, we prepare a standardized dataset and perform a comprehensive global environmental characterization for 17,883 of the world's marine islands >1 km2 (∼98% of total island area). We consider area, temperature, precipitation, seasonality in temperature and precipitation, past climate change velocity, elevation, isolation, and past connectivity-key island characteristics and drivers of ecosystem processes. We find that islands are significantly cooler, wetter, and less seasonal than mainlands. Constrained by their limited area, they show less elevational heterogeneity. Wet temperate climates are more prevalent on islands, whereas desert climates are comparatively rare. We use ordination and clustering to characterize islands in multidimensional environmental space and to delimit island ecoregions, which provides unique insights into the environmental configuration and diversity of the world's islands. Combining ordination and classification together with global environmental data in a common framework opens up avenues for a more integrative use of islands in biogeography, macroecology, and conservation. To showcase possible applications of the presented data, we predict vascular plant species richness for all 17,883 islands based on statistically derived environment-richness relationships.

Hubo C.,University of Gottingen | Krott M.,University of Gottingen
Forest Policy and Economics | Year: 2013

A balanced management of forest conflicts that considers both nature conservation and economic concerns requires the recognition and communication of these concerns within the decision-making procedures of public administration. Thus, the visibility of conflicts is an important condition for balanced conflict resolutions. The analysis of public administration forms shows, theoretically and empirically, that different patterns support the visibility of conflicts in specific ways, mainly by offering the potential for the development of independent expertise and its integration into consideration procedures. Combining different organisation forms increases the potential for balanced conflict resolutions. The effect of this potential depends on its utilization by administrative resources. In the case of administrative reform in the German federal state of Lower Saxony, the utilization of this potential was neglected, reducing the visibility of nature conservation concerns. This had far-reaching consequences for the resolution of forest conflicts. Economically-biased resolutions become camouflaged by keeping conservation issues invisible, neglecting them within administrative procedures and within the operations of forest owners whilst making legal and political claims to their consideration, so as to be able to pretend that conflict resolutions are balanced in their approach. © 2012 Elsevier B.V.

Koelling S.,University of Gottingen | Miosge N.,University of Gottingen
Arthritis and Rheumatism | Year: 2010

Objective. Osteoarthritis (OA), a mainly degenerative disease, is known to be multifactorial in origin. Gene expression patterns vary between populations and sexes. Sex hormone receptors have been described in the cartilage tissue of animals and humans. We undertook this study to determine whether the regenerative potential of chondrogenic progenitor cells (CPCs) present in the arthritic tissue during the late stages of human OA might also be subject to sex-specific differences and influenced by sex steroids. Methods. We analyzed sex-specific differences in the regenerative potential of CPCs and the involvement of sex hormones in vitro in cartilage samples from patients with late-stage knee OA, using electrochemilu-minescence immunoassay, microarray analysis, realtime reverse transcription-polymerase chain reaction, immunohistochemistry, Western blot analysis, fluorescence-activated cell sorting, and cell culture. Results. We detected expression of estrogen and testosterone in the OA synovial fluid as well as CPCs positive for estrogen receptor α (ERα), ERβ, and androgen receptor. Both hormones influenced the expression of all 3 receptor genes as well as the chondrogenic potential of CPCs by regulating gene expression of Sox9, Runx2, type II collagen, and type I collagen. We found regulatory effects on the collagens via Sox9 and Runx2 as well as regulatory effects independent of these transcription factors. These effects were sex-specific and relied on hormone concentrations. Conclusion. Physiologic concentrations of testosterone in men and premenopausal concentrations of estrogen in women have a positive effect on the chondrogenic potential of CPCs in vitro. Therefore, strategies of hormone replacement in the synovial fluid of women and men might have beneficial effects on the regenerative potential of arthritic cartilage tissue in late stages of human OA. © 2010, American College of Rheumatology.

Zhang K.,University of Gottingen | Brotzmann M.,University of Gottingen | Hofsass H.,University of Gottingen
New Journal of Physics | Year: 2011

In this paper, we report on the self-organized pattern formation on Si surfaces driven by Fe surfactant atoms. Si substrates were irradiated with 5keV Xe ions at normal incidence and ion fluences up to 5 × 10 17Xe+cm-2 under continuous deposition of Fe surfactant atoms. In the absence of Fe deposition, uniform flat surfaces were obtained. With Fe surfactants, pronounced patterns, such as dots, combinations of dots and ripples and ripples with about 100 nm wavelength, were generated. The Fe coverage and deposition direction determine the pattern type and the pattern orientation, respectively. A critical Fe steady-state coverage for onset of dot formation and onset of ripple formation ranges between 2 × 10 15 and 6 × 1015 Fecm-2. With increasing ion fluence, the pattern contrast increases but the pattern type remains unchanged. The surface region consists of a thin amorphous FexSi layer with x ≈ 0.2 in the ripple and dot regions and x ≈ 0.03 in the intermediate regions. Pattern formation is explained by ion-induced diffusion and phase separation of the initially flat amorphous FexSi layer and subsequent ion beam erosion with composition-dependent sputter yield. Directed deposition of Fe causes preferential deposition and shadowing and determines the final pattern orientation and morphology. © IOP Publishing Ltd and Deutsche Physikalische Gesellschaft.

On the plateau of the Göttingen Forest, an area of 12 ha of a ca. 145-yr-old species-rich submontane calciphytic beech forest (Hordelymo-Fagetum lathyretosum) was fenced for an ecosystem research project in 1980. Within this area a large transect (GT) of 2.81 ha with 281 10x10 m quadrats has been laid out as a permanent plot to study natural dynamics. From 1981 to 2011 every 10 years flora and vegetation have been recorded in detail (vertical structure, estimate of cover degree of all species in %, vegetation mapping). The results over the three decades are presented in tables of herb layer composi-tion, as well as quantitative distribution maps of selected species and vegetation maps. Already within the first decade a shrub layer mainly of young trees has developed in parts of the transect. Some chan-ges in the herb layer were observed. A frequency table with all 83 species found within 30 years (Ta-ble 1) shows many plants (33) with decreasing tendency besides a stock of constant species. Allium ursinum, Cardamine bulbifera, Dryopteris carthusiana, Hedera helix, and Neottia nidus-avis were the only species showing a pronounced increase. Different types of single species dominance or mixture were mapped out, with the key species Aconitum lycoctonum, Allium ursinum, Anemone nemorosa, and Mercurialis perennis.-For a long time the antagonism of Allium (distinct increase) and Mercurialis (strong decrease) was particularly striking, resulting in a strong increase of the Allium ursinum domi-nance type within the three decades. While on the microscale of quadrats a pronounced change of the floristic composition could be recognized, on the mesoscale of the total stand floristic constancy could also be found.-The discussion reviews possible causes and interpretations for the ascertained changes. Apart from local causes such as fencing and competitive power of Allium ursinum, comparison with the literature yields some more global trends. For a long time deciduous forests with no or negligible silvi-cultural treatment have undergone increasing canopy closure, leading to a shadier and more humid microclimate. Since some decades nutrient-demanding species may have benefitted from nitrogen deposition. Within the last two decades increasing effects of global warming such as a prolonged grow-ing season have been observed. As a new phenomenon the dieback of ash by fungal attack has been described.

Schusser C.,University of Gottingen
Forest Policy and Economics | Year: 2013

Recent and ongoing research has begun to question the efficacy of community forestry programs. In particular, analysis seems to reveal that devolution of power to the local resource user does not happen. Nevertheless, it also appears that community forestry programs do deliver some of their promises. Especially, the biodiversity of the resources involved is often improved. But who determines this, if not the local resource user? This article seeks to answer this by analyzing the biodiversity of 14 community forests in Namibia. The authors apply their power theory and methodology to identify the powerful, actors and these actors' interests. Finally, the author relates his findings to the real outcomes for biodiversity. The article concludes that biodiversity is only in the interest of a few powerful actors who have used their power to achieve a positive outcome for biodiversity. Therefore, the article argues that biodiversity in community forestry depends on the interests of powerful actors. © 2012 Elsevier B.V.

Irniger S.,University of Gottingen
Molecular Microbiology | Year: 2011

Ime2 of the budding yeast Saccharomyces cerevisiae belongs to a family of conserved protein kinases displaying sequence similarities to both cyclin-dependent kinases and mitogen-activated protein kinases. Ime2 has a pivotal role for meiosis and sporulation. The involvement of this protein kinase in the regulation of various key events in meiosis, such as the initiation of DNA replication, the expression of meiosis-specific genes and the passage through the two consecutive rounds of nuclear divisions has been characterized in detail. More than 20 years after the identification of the IME2 gene, a recent report has provided the first evidence for a function of this gene outside of meiosis, which is the regulation of pseudohyphal growth. In the last few years, Ime2-related protein kinases from various fungal species were studied. Remarkably, these homologues are not generally required for meiosis, but instead have other specific tasks. In filamentous ascomycete species, Ime2 homologues are involved in the inhibition of fruiting body formation in response to environmental signals. In the pathogenic basidiomycetes Ustilago maydis and Cryptococcus neoformans, members of this kinase family apparently have primary roles in regulating mating. Thus, Ime2-related kinases exhibit an amazing variety in controlling sexual developmental programs in fungi. © 2011 Blackwell Publishing Ltd.

Claussen I.,University of Gottingen | Mayr S.G.,University of Leipzig
New Journal of Physics | Year: 2011

We report on vibrating reed measurements combined with density functional theory-based calculations to assess the elastic and damping properties of Fe-Pd ferromagnetic shape memory alloy splats. While the austenite-martensite phase transformation is generally accompanied by lattice softening, a severe modulus defect and elevated damping behavior are characteristic of the martensitic state. We interpret the latter in terms of twin boundary motion between pinning defects via partial 'twinning' dislocations. Energy dissipation is governed by twin boundary drag, primarily due to lattice imperfections, as concluded from the temperature dependence of damping and related activation enthalpies. © IOP Publishing Ltd and Deutsche Physikalische Gesellschaft.

The amount of resection is closely related to survival in brain tumours. To enhance resection, especially intraoperative magnetic resonance imaging (MRI) has been applied. The aim of this prospective, randomized study was to test if intraoperative 3-D ultrasound likewise can be used for resection control. 16 patients, who underwent surgery for intraaxial tumours in non-eloquent brain areas, were initially included into this prospective study. In two patients, the small size of the craniotomy hindered intraoperative ultrasound imaging. In 14 patients, 3-D ultrasound images were obtained before and after opening of the dura, during tumour removal, prior to evaluation by a blinded investigator for identification of tumour remnants, and after dura closure. Seven patients were randomized to complete tumour removal according to the impression of the surgeon (group 1). Seven patients were randomized to incomplete tumour removal (tumour remnant <1cm) (group 2); in these patients, the neurosurgeon intentionally left a tumour remnant prior to evaluation by the blinded investigator. The tumour remnant was then removed. It was tested if 3-D ultrasound can correctly identify complete and incomplete tumour resection. All patients underwent early postoperative MRI. In two patients (one each of the two groups) the image quality was too poor for a meaningful intraoperative evaluation. In the six patients randomized for incomplete tumour removal, 3-D ultrasound correctly identified tumour remnants in four patients (67%). In six patients randomized for complete tumour removal, 3-D ultrasound confirmed complete tumour resection in three patients. In addition, 3-D ultrasound identified correctly one tumour remnant in a patient randomized for complete tumour removal. Thus, the sensitivity for tumour remnant detection increased to 71% (five of seven patients) and that of confirmation of complete tumour removal was 60 % (three of five patients). The number of investigated patients is still to low to allow definite conclusions. However, the study results suggest, that 3-D ultrasound is especially helpful for detection of overseen brain tumour tissue.

Karlovsky P.,University of Gottingen
Applied Microbiology and Biotechnology | Year: 2011

Deoxynivalenol (DON) is the major mycotoxin produced by Fusarium fungi in grains. Food and feed contaminated with DON pose a health risk to humans and livestock. The risk can be reduced by enzymatic detoxification. Complete mineralization of DON by microbial cultures has rarely been observed and the activities turned out to be unstable. The detoxification of DON by reactions targeting its epoxide group or hydroxyl on carbon 3 is more feasible. Microbial strains that de-epoxidize DON under anaerobic conditions have been isolated from animal digestive system. Feed additives claimed to de-epoxidize trichothecenes enzymatically are on the market but their efficacy has been disputed. A new detoxification pathway leading to 3-oxo-DON and 3-epi-DON was discovered in taxonomically unrelated soil bacteria from three continents; the enzymes involved remain to be identified. Arabidopsis, tobacco, wheat, barley, and rice were engineered to acetylate DON on carbon 3. In wheat expressing DON acetylation activity, the increase in resistance against Fusarium head blight was only moderate. The Tri101 gene from Fusarium sporotrichioides was used; Fusarium graminearum enzyme which possesses higher activity towards DON would presumably be a better choice. Glycosylation of trichothecenes occurs in plants, contributing to the resistance of wheat to F. graminearum infection. Marker-assisted selection based on the trichothecene-3-O-glucosyltransferase gene can be used in breeding for resistance. Fungal acetyltransferases and plant glucosyltransferases targeting carbon 3 of trichothecenes remain promising candidates for engineering resistance against Fusarium head blight. Bacterial enzymes catalyzing oxidation, epimerization, and less likely de-epoxidation of DON may extend this list in future. © 2011 The Author(s).

Paczkowski S.,University of Gottingen | Schutz S.,University of Gottingen
Applied Microbiology and Biotechnology | Year: 2011

Volatile emission during vertebrate decay is a complex process that is understood incompletely. It depends on many factors. The main factor is the metabolism of the microbial species present inside and on the vertebrate. In this review, we combine the results from studies on volatile organic compounds (VOCs) detected during this decay process and those on the biochemical formation of VOCs in order to improve our understanding of the decay process. Micro-organisms are the main producers of VOCs, which are by- or end-products of microbial metabolism. Many microbes are already present inside and on a vertebrate, and these can initiate microbial decay. In addition, micro-organisms from the environment colonize the cadaver. The composition of microbial communities is complex, and communities of different species interact with each other in succession. In comparison to the complexity of the decay process, the resulting volatile pattern does show some consistency. Therefore, the possibility of an existence of a time-dependent core volatile pattern, which could be used for applications in areas such as forensics or food science, is discussed. Possible microbial interactions that might alter the process of decay are highlighted. © 2011 The Author(s).

Reiners A.,University of Gottingen | Mohanty S.,Imperial College London
Astrophysical Journal | Year: 2012

Angular momentum evolution in low-mass stars is determined by initial conditions during star formation, stellar structure evolution, and the behavior of stellar magnetic fields. Here we show that the empirical picture of angular momentum evolution arises naturally if rotation is related to magnetic field strength instead of to magnetic flux and formulate a corrected braking law based on this. Angular momentum evolution then becomes a strong function of stellar radius, explaining the main trends observed in open clusters and field stars at a fewGyr: the steep transition in rotation at the boundary to full convection arises primarily from the large change in radius across this boundary and does not require changes in dynamo mode or field topology. Additionally, the data suggest transient core-envelope decoupling among solar-type stars and field saturation at longer periods in very low mass stars. For solar-type stars, our model is also in good agreement with the empirical Skumanich law. Finally, in further support of the theory, we show that the predicted age at which low-mass stars spin down from the saturated to unsaturated field regimes in our model corresponds remarkably well to the observed lifetime of magnetic activity in these stars. © 2012. The American Astronomical Society. All rights reserved.

Tanriverdi V.,University of Gottingen | Tilgner A.,University of Gottingen
New Journal of Physics | Year: 2011

The spectrum of temporal fluctuations of total magnetic energy for several dynamo models is different from white noise at frequencies smaller than the inverse of the turnover time of the underlying turbulent velocity field. Examples of this phenomenon are known from previous work, and we add in this paper simulations of the G O Roberts dynamo and of convectively driven dynamos in rotating spherical shells. The appearance of colored noise in the magnetic energy is explained by simple phenomenological models. The Kolmogorov theory of turbulence is used to predict the spectrum of kinetic and magnetic energy fluctuations in the inertial range. © IOP Publishing Ltd and Deutsche Physikalische Gesellschaft.

Pruser H.,University of Gottingen | Wenderoth M.,University of Gottingen | Dargel P.E.,University of Gottingen | Weismann A.,University of Gottingen | And 3 more authors.
Nature Physics | Year: 2011

The Kondo effect, one of the first recognized correlation phenomena in condensed-matter physics1, has regained attention because of scanning tunnelling spectroscopy (STS) experiments carried out on single magnetic impurities2,3. Despite the subnanometre resolution capability of local probe techniques, one of the fundamental aspects of Kondo physics, its spatial extension, is still subject to discussion. Until now all STS studies on single adsorbed atoms have shown that observable Kondo features vanish rapidly with increasing distance from the impurity4-9. Here we report on a hitherto unobserved long-range Kondo signature for single magnetic atoms of Fe and Co buried under a Cu(100) surface. We present a theoretical interpretation of the measured signatures using a combined approach of band-structure and many-body numerical renormalization group calculations. These are in excellent agreement with the rich spatially and spectroscopically resolved experimental data. © 2011 Macmillan Publishers Limited. All rights reserved.

Meiser W.,University of Gottingen | Buback M.,University of Gottingen
Macromolecular Rapid Communications | Year: 2012

We have presented an EPR-based approach for deducing the RAFT equilibrium constant, Keq, of a dithiobenzoate-mediated system [Meiser, W. and Buback M. Macromol. Rapid Commun. 2011, 32, 1490]. Our value is by four orders of magnitude below Keq from ab initio calculations for the identical monomer-free system. Junkers et al. [Macromol. Rapid Commun. 2011, 32, 1891] claim that our EPR approach would be model dependent and our data could be equally well fitted by assuming slow addition of radicals to the RAFT agent and slow fragmentation of the so-obtained intermediate radical as well as high cross-termination rate. By identification of all side products, our EPR-based method is shown to be model independent and to provide reliable Keq values, which demonstrate the validity of the intermediate radical termination model. An EPR-based approach for deducing the RAFT equilibrium constant for the model system CIP-CPDB in conjunction with product analysis via NMR proves that the intermediate radical undergoes fast fragmentation and terminates with CIP radicals. The cross-termination products partly undergo missing step reactions. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Hegerfeldt G.C.,University of Gottingen
Physical Review Letters | Year: 2013

A remarkably simple result is derived for the minimal time Tminâ ¡ required to drive a general initial state to a final target state by a Landau-Zener-type Hamiltonian or, equivalently, by time-dependent laser driving. The associated protocol is also derived. A surprise arises for some states when the interaction strength is bounded by a constant c. Then, for large c, the optimal driving is of type bang-off-bang and for increasing c one recovers the unconstrained result. However, for smaller c the optimal driving can suddenly switch to bang-bang type. We discuss the notion of quantum speed limit time. © 2013 American Physical Society.

Siewert I.,University of Gottingen
Chemistry - A European Journal | Year: 2015

Proton-coupled electron transfer (PCET) reactions are essential for a wide range of natural energy-conversion reactions and recently, the impact of PCET pathways has been exploited in artificial systems, too. The Minireview highlights PCET reactions catalysed by first-row transition-metal complexes, with a focus on the water oxidation, the oxygen reduction, the hydrogen evolution, and the CO2 reduction reaction. Special attention will be paid to systems in which the impact of such pathways is deduced by comparison to systems with "electron-only"-transfer pathways. © 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Gerwick E.,University of Gottingen
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2013

We derive a recursion relation for the analytic leading logarithmic coefficients of a final state gluon cascade. We demonstrate the potential of our method by analytically computing the rate coefficients for the emission of up to 80 gluons in both the exclusive-kt (Durham) and generalized inclusive-kt class of jet algorithms. There is a particularly simple form for the ratios of resolved coefficients. We suggest potential applications for our method including the efficient generation of shower histories. © 2013 American Physical Society.

Latif M.A.,University of Gottingen | Schleicher D.R.G.,University of Gottingen | Schmidt W.,University of Gottingen
Monthly Notices of the Royal Astronomical Society | Year: 2014

Observations of quasars at z > 6 report the existence of a billion solar mass black holes. Comprehending their formation in such a short time-scale is a matter of ongoing research. One of the most promising scenarios to assemble supermassive black holes is a monolithic collapse of protogalactic gas clouds in atomic cooling haloes with Tvir ≥ 104 K. In this paper, we study the amplification and impact of magnetic fields during the formation of seed black holes in massive primordial haloes. We perform high-resolution cosmological magnetohydrodynamic simulations for four distinct haloes and follow their collapse for a few free-fall times until the simulations reach a peak density of 7 × 10-10 g cm-3. Our findings show that irrespective of the initial seed field, the magnetic field strength reaches a saturated state in the presence of strong accretion shocks. Under such conditions, the growth time becomes very short and amplification occurs rapidly within a small fraction of the free-fall time. We find that the presence of such strong magnetic fields provides additional support against gravity and helps in suppressing fragmentation. Massive clumps of a few hundred solar masses are formed at the end of our simulations and high accretion rates of 1M⊙ yr-1 are observed. We expect that in the presence of such accretion rates, the clumps will grow to form supermassive stars of ~105M⊙. Overall, the role of the magnetic fields seems supportive for the formation of massive black holes. © 2014 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society.

Harlov D.E.,Helmholtz Center Potsdam | Van Den Kerkhof A.,University of Gottingen | Johansson L.,Lund University
Journal of Petrology | Year: 2013

The Varberg-Torpa charnockite-granite association (Varberg, SW Sweden) consists of the magmatic Varberg charnockite (1399±12 Ma) and theTorpa granite (1380±12 Ma). TheTorpa granite is both continuous and, based on its whole-rock geochemistry, synmagmatic with the Varberg charnockite. The granite body also contains a number of charnockite inliers. P-T estimation using garnet-clinopyroxene and orthopyroxene-clinopyroxene Fe-Mg exchange thermometry and garnet-orthopyroxene-plagioclase-quartz barometry gives temperatures and pressures (750-8508C; 800-850MPa) that most probably approximate the P-Tconditions during emplacement of the charnockite compared with a lower crystallization temperature (650-700°C) for the granite. The earliest recognized fluid inclusions in both the granite and charnockite consist of H2O-CO2 mixtures (H2O volume fraction 0·2-0·7). Fluid inclusions in the charnockite are characterized by high CO2 densities (up to 1·0 gcm-3; 40-90% bulk CO2), of probable magmatic origin, and are best preserved in garnet, plagioclase, and fluorapatite (in order of decreasing CO2 densities),and sometimes also in clinopyroxene. Fluid inclusions with the highest CO2 densities (1·08-1·10 gcm-3) are found in quartz (Th -31 to -36°C) and may have originated under high P-Tconditions during emplacement and cooling of the charnockite. Magmatic fluids in the granite correspond to aqueous- carbonic inclusions with an estimated bulk composition (mol %) of H2O 73%, CO2 25%, NaCl 2%. The salinity of the solutes in the granite (typically 14-20 wt % NaCl-eq.) is generally higher than for the charnockite (0-8 wt % NaCl-eq.). Field, petrographic,mineralogical, geochemical, and fluid inclusion evidence indicates that, compared with the H2O-rich granite, the magma responsible for the charnockite had a preponderance of CO2 over H2O, which lowered the H2Oactivity in the melt, stabilizing ortho- and clinopyroxene. This evidence alsosupports the idea that the granite and charnockite were derived from a common source magma (most probably a fluid-rich basalt at the base of the crust) as a result of fractional crystallization. © The Author 2012. Published by Oxford University Press. All rights reserved.

Fenner S.,University of Gottingen | Ackermann L.,University of Gottingen
Green Chemistry | Year: 2016

The C-H carboxylation of heteroarenes was achieved under transition metal-free reaction conditions with naturally abundant CO2 as the C1 source at relatively low temperature. The C-H carboxylation was mediated by KOt-Bu at atmospheric pressure of CO2, and thereby provided atom- and step-economical access to various heteroaromatic carboxylic acid derivatives. © 2016 The Royal Society of Chemistry.

Zinngrebe Y.M.,University of Gottingen
Ecology and Society | Year: 2016

In the mega-diverse country Peru, a resource intensive development model collides with the interest of conserving biodiversity. Peruvian biodiversity experts have developed different lines of argumentation as to how to integrate conservation into the sustainable development of their country. Applying grounded theory, I define five groups of conservation narratives based on the analysis of 72 qualitative interviews with experts working in areas of biodiversity conservation. I have labeled them: biodiversity protectionists, biodiversity traditionalists, biodiversity localists, biodiversity pragmatists, and biodiversity capitalists. These groups are each discussed in connection with what they have to say about biodiversity in relation to human life, valuation and knowledge systems, participation and leadership, substitutability of natural capital, and its predominant political strategy. In a second step, a comparative analysis of the dominant and diverging political perspectives is made. I argue that by deconstructing underlying premises and ideologies, common ground and possible opportunities for collaboration can be identified. Moreover, although the presented results can serve as a discussion scaffold to organize conservation debates in Peru, this example demonstrates how the terms biodiversity and sustainability are operationalized in conservation narratives. © 2016 by the author(s).

Fischer A.,University of Gottingen | Fischer A.,German Center for Neurodegenerative Diseases
EMBO Journal | Year: 2014

Recent data support the view that epigenetic processes play a role in memory consolidation and help to transmit acquired memories even across generations in a Lamarckian manner. Drugs that target the epigenetic machinery were found to enhance memory function in rodents and ameliorate disease phenotypes in models for brain diseases such as Alzheimer's disease, Chorea Huntington, Depression or Schizophrenia. In this review, I will give an overview on the current knowledge of epigenetic processes in memory function and brain disease with a focus on Morbus Alzheimer as the most common neurodegenerative disease. I will address the question whether an epigenetic therapy could indeed be a suitable therapeutic avenue to treat brain diseases and discuss the necessary steps that should help to take neuroepigenetic research to the next level. As part of our review series on Molecular Memory, Andre Fischer discusses epigenetic processes leading to memory formation and transgenerational inheritance under physiological and pathological conditions such as Alzheimer's disease. © 2014 The Author. Published under the terms of the CC BY NC ND license.

Rizzoli S.O.,University of Gottingen
EMBO Journal | Year: 2014

Synaptic vesicle recycling is one of the best-studied cellular pathways. Many of the proteins involved are known, and their interactions are becoming increasingly clear. However, as for many other pathways, it is still difficult to understand synaptic vesicle recycling as a whole. While it is generally possible to point out how synaptic reactions take place, it is not always easy to understand what triggers or controls them. Also, it is often difficult to understand how the availability of the reaction partners is controlled: how the reaction partners manage to find each other in the right place, at the right time. I present here an overview of synaptic vesicle recycling, discussing the mechanisms that trigger different reactions, and those that ensure the availability of reaction partners. A central argument is that synaptic vesicles bind soluble cofactor proteins, with low affinity, and thus control their availability in the synapse, forming a buffer for cofactor proteins. The availability of cofactor proteins, in turn, regulates the different synaptic reactions. Similar mechanisms, in which one of the reaction partners buffers another, may apply to many other processes, from the biogenesis to the degradation of the synaptic vesicle. Silvio Rizzoli reviews the different steps and mechanisms involved in synaptic vesicle biogenesis and recycling. © 2014 The Authors.

Mamani M.,University of Gottingen | Worner G.,University of Gottingen | Sempere T.,University Paul Sabatier
Bulletin of the Geological Society of America | Year: 2010

Compositional variations of Central Andean subduction-related igneous rocks reflect the plate-tectonic evolution of this active continental margin through time and space. In order to address the effect on magmatism of changing subduction geometry and crustal evolution of the upper continental plate during the Andean orogeny, we compiled more than 1500 major- and trace-element data points, and 650 Sr-, 610 Nd-, and 570 Pb-isotopic analyses of Mesozoic-Cenozoic (190-0 Ma) magmatic rocks in southern Peru and northern Chile (Central Andean orocline), mostly from new data and the literature. This data set documents compositional variations of magmas since Jurassic time, with a focus on the Neogene period, when major crustal thickening developed and its influence on magma composition was most pronounced. We relate the observed variations in Sr/Y, La/Yb, La/Sm, Sm/Yb, and Dy/Yb ratios, as well as in Sr-, Nd-, and Pb-isotopic ratios, to the crustal structure and evolution of the Central Andean orocline. In particular, the evolution of Dy/Yb and Sm/Yb ratios, which track the presence of the higher-pressure minerals amphibole and garnet, respectively, in the lower crust, documents that crustal thickness has grown through time. Spatial variations in trace elements and isotopic ratios further suggest that crustal domains of distinct composition and age have influenced magma composition through some assimilation. The crustal input in Quaternary magmas is quantified to have been between 7% and 18% by simple two-components mixing. When comparing our geochemical data set to the geological record of uplift and crustal thickening, we observe a correlation between the composition of magmatic rocks and the progression of Andean orogeny. In particular, our results support the interpretation that major crustal thickening and uplift were initiated in the mid-Oligocene (30 Ma) and that crustal thickness has kept increasing until present day. Our data do not support delamination as a general cause for major late Miocene uplift in the Central Andes and instead favor continued crustal thickening. © 2009 Geological Society of America.

Stadelmann C.,University of Gottingen
Current Opinion in Neurology | Year: 2011

Purpose of Review: Multiple sclerosis (MS) treatments targeting the inflammatory nature of the disease have become increasingly effective in recent years. However, our efforts at targeting the progressive disease phase have so far been largely unsuccessful. This has led to the hypothesis that disease mechanisms independent of an adaptive immune response contribute to disease progression and closely resemble neurodegeneration. Recent Findings: Nonfocal, diffuse changes in the MS brain, especially axonal loss and mitochondrial dysfunction, prove better correlates of disability than total lesion load and have been associated with disease progression. Molecular changes in nondemyelinated MS tissue also suggest that alterations in the MS brain are widespread and consist of pro-inflammatory as well as anti-inflammatory responses. However, local lymphocytic inflammation and microglial activation are salient features of the chronic disease, and T-cell-mediated inflammation contributes to tissue damage. In addition, neuroaxonal cytoskeletal alterations have been associated with disease progression. Summary: Our knowledge of the molecular mechanisms leading to neuroaxonal damage and demise in MS is steadily increasing. Experimental therapies targeting neuroaxonal ionic imbalances and energy metabolism in part show promising results. A better understanding of the molecular mechanisms underlying chronic progression will substantially aid the development of new treatment strategies. © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins.

Kool D.M.,Wageningen University | Dolfing J.,Northumbria University | Wrage N.,University of Gottingen | Van Groenigen J.W.,Wageningen University
Soil Biology and Biochemistry | Year: 2011

Soils are the major source of the greenhouse gas nitrous oxide (N2O) to our atmosphere. A thorough understanding of terrestrial N2O production is therefore essential. N2O can be produced by nitrifiers, denitrifiers, and by nitrifiers paradoxically denitrifying. The latter pathway, though well-known in pure culture, has only recently been demonstrated in soils. Moreover, nitrifier denitrification appeared to be much less important than classical nitrate-driven denitrification. Here we studied a poor sandy soil, and show that when moisture conditions are sub-optimal for denitrification, nitrifier denitrification can be a major contributor to N2O emission from this soil. We conclude that the relative importance of classical and nitrifier denitrification in N2O emitted from soil is a function of the soil moisture content, and likely of other environmental conditions as well. Accordingly, we suggest that nitrifier denitrification should be routinely considered as a major source of N2O from soil. © 2010 Elsevier Ltd.

Agis-Balboa R.C.,University of Gottingen | Fischer A.,University of Gottingen | Fischer A.,German Center for Neurodegenerative Diseases
Cellular and Molecular Life Sciences | Year: 2014

Extinction of fear memory is a particular form of cognitive function that is of special interest because of its involvement in the treatment of anxiety and mood disorders. Based on recent literature and our previous findings (EMBO J 30(19):4071-4083, 2011), we propose a new hypothesis that implies a tight relationship among IGF signaling, adult hippocampal neurogenesis and fear extinction. Our proposed model suggests that fear extinction-induced IGF2/IGFBP7 signaling promotes the survival of neurons at 2-4 weeks old that would participate in the discrimination between the original fear memory trace and the new safety memory generated during fear extinction. This is also called "pattern separation", or the ability to distinguish similar but different cues (e.g., context). To understand the molecular mechanisms underlying fear extinction is therefore of great clinical importance. © 2013 Springer Basel.

Dosch R.,University of Gottingen
Critical Reviews in Biochemistry and Molecular Biology | Year: 2015

In many animals, factors deposited by the mother into the egg control the earliest events in development of the zygote. These maternal RNAs and proteins play critical roles in oocyte development and the earliest steps of embryogenesis such as fertilization, cell division and embryonic patterning. Here, this article summarizes recent discoveries made on the maternal control of germline specification in zebrafish. Moreover, this review will discuss the major gaps remaining in our understanding of this process and highlight recent technical innovations in zebrafish, which allow tackling some of these questions in the near future. © 2014 Informa Healthcare USA, Inc. All rights reserved.

Palus S.,University of Gottingen | Von Haehling S.,University of Gottingen | Springer J.,University of Gottingen
International Journal of Cardiology | Year: 2014

The syndrome of cachexia, i.e. involuntaryweight loss in patientswith underlying diseases, sarcopenia, i.e. loss of muscle mass due to ageing, and general muscle atrophy from disuse and/or prolonged bed rest have received more attention over the last decades. All lead to a higher morbidity and mortality in patients and therefore, they represent a major socio-economic burden for the society today. This mini-reviewlooks at recent developments in basic research that are relevant to the loss of skeletalmuscle. It aims to cover the most significant publication of last three years on the causes and effects of muscle wasting, new targets for therapy development and potential biomarkers for assessing skeletal musclemass. The targets include 1) E-3 ligases: TRIM32, SOCS1 and SOCS3 by involving the elongin BC ubiquitin-ligase, Cbl-b, culling 7, Fbxo40, MG53 (TRIM72) and the mitochondrial Mul1, 2) the kinase MST1 and 3) the G-protein Gαi2. D(3)-creatine has the potential to be used as a novel biomarker that allows to monitor actual change in skeletal muscle mass over time. In conclusion, significant development efforts are being made by academic groups aswell as numerous pharmaceutical companies to identify newtargets and biomarkers muscle, asmusclewasting represents a great medical need, but no therapies have been approved in the last decades. © 2014 Elsevier Ireland Ltd. All rights reserved.

Fornasiero E.F.,European Neuroscience Institute | Fornasiero E.F.,University of Gottingen | Opazo F.,European Neuroscience Institute | Opazo F.,University of Gottingen
BioEssays | Year: 2015

The recent 2014 Nobel Prize in chemistry honored an era of discoveries and technical advancements in the field of super-resolution microscopy. However, the applications of diffraction-unlimited imaging in biology have a long road ahead and persistently engage scientists with new challenges. Some of the bottlenecks that restrain the dissemination of super-resolution techniques are tangible, and include the limited performance of affinity probes and the yet not capillary diffusion of imaging setups. Likewise, super-resolution microscopy has introduced new paradigms in the design of projects that require imaging with nanometer-resolution and in the interpretation of biological images. Besides structural or morphological characterization, super-resolution imaging is quickly expanding towards interaction mapping, multiple target detection and live imaging. Here we review the recent progress of biologists employing super-resolution imaging, some pitfalls, implications and new trends, with the purpose of animating the field and spurring future developments. © 2015 WILEY Periodicals, Inc.

Schurmann F.-W.,University of Gottingen
Arthropod Structure and Development | Year: 2016

In the insect brain, mushroom bodies represent a prominent central neuropil for multisensory integration and, crucially, for learning and memory. For this reason, special attention has been focused on its small chemical synapses. Early studies on synaptic types and their distribution, using conventional electron microscopy, and recent publications have resolved basic features of synaptic circuits.More recent studies, using experimental methods for resolving neurons, such as immunocytochemistry, genetic labelling, high resolution confocal microscopy and more advanced electron microscopy, have revealed many new details about the fine structure and molecular contents of identifiable neurons of mushroom bodies and has led to more refined modelling of functional organisation. Synaptic circuitries have been described in most detail for the calyces. In contrast, the mushroom bodies' columnar peduncle and lobes have been explored to a lesser degree. In dissecting local microcircuits, the scientist is confronted with complex neuronal compartmentalisation and specific synaptic arrangements. This article reviews classical and modern studies on the fine structure of synapses and their networks in mushroom bodies across several insect species. © 2016 Elsevier Ltd.

Fischer A.,University of Gottingen | Fischer A.,German Center for Neurodegenerative Diseases
Neuropharmacology | Year: 2014

Alzheimer' s disease (AD) is the most common form of dementia causing an increasing emotional and economical burden to our societies. Although much progress has been made regarding the molecular mechanisms that underlie AD pathogenesis effective therapies are not available yet. The emerging field of neuroepigenetics has provided evidence that de-regulation of epigenetic processes play a role in AD. In this article we will critically review the primary research data that led to the hypothesis that targeting histone-modifying enzymes could be used to treat AD pathogenesis and address the question if the field is ready to translate such findings into clinical application. © 2014 Elsevier Ltd. All rights reserved.

Wichmann C.,University of Gottingen | Moser T.,University of Gottingen
Cell and Tissue Research | Year: 2015

In the mammalian cochlea, sound is encoded at synapses between inner hair cells (IHCs) and type I spiral ganglion neurons (SGNs). Each SGN receives input from a single IHC ribbon-type active zone (AZ) and yet SGNs indefatigably spike up to hundreds of Hz to encode acoustic stimuli with submillisecond precision. Accumulating evidence indicates a highly specialized molecular composition and structure of the presynapse, adapted to suit these high functional demands. However, we are only beginning to understand key features such as stimulus–secretion coupling, exocytosis mechanisms, exo–endocytosis coupling, modes of endocytosis and vesicle reformation, as well as replenishment of the readily releasable pool. Relating structure and function has become an important avenue in addressing these points and has been applied to normal and genetically manipulated hair cell synapses. Here, we review some of the exciting new insights gained from recent studies of the molecular anatomy and physiology of IHC ribbon synapses. © 2015, The Author(s).

The intrinsic reactivity of 4 metallic iron materials (Fe0) was investigated in batch and column experiments. The Fe0 reactivity was characterised by the extent of aqueous fixation of in-situ leached arsenic (As). Air-homogenised batch experiments were conducted for 1 month with 10.0 g/ℓ of an As-bearing rock (ore material) and 0.0 or 5.0 g/ℓ of Fe0. Column experiments were performed for 2 and 3 months. Each dynamic experiment was made up of 2 glass columns in series. The first column contained 2.5 or 5.0 g of the ore material and the second column 0.0 or 5.0 g of a Fe0 material. Results showed no significant reactivity difference in batch studies for all 4 materials; ZVI2 was by far the most reactive material in column experiments. This observation was attributed to the relative kinetics of production of aqueous As and Fe species under the experimental conditions and their impact on the formation of a protective film on Fe0. Accordingly, no protective film could be built at the surface of the least reactive materials. The results corroborated the urgent need for unified experimental procedures to characterise Fe0 materials.

Can A.,University of Maryland Baltimore County | Schulze T.G.,University of Gottingen | Gould T.D.,University of Maryland Baltimore County
Pharmacology Biochemistry and Behavior | Year: 2014

Mood disorders, including bipolar disorder and depression, are relatively common human diseases for which pharmacological treatment options are often not optimal. Among existing pharmacological agents and mood stabilizers used for the treatment of mood disorders, lithium has a unique clinical profile. Lithium has efficacy in the treatment of bipolar disorder generally, and in particular mania, while also being useful in the adjunct treatment of refractory depression. In addition to antimanic and adjunct antidepressant efficacy, lithium is also proven effective in the reduction of suicide and suicidal behaviors. However, only a subset of patients manifests beneficial responses to lithium therapy and the underlying genetic factors of response are not exactly known. Here we discuss preclinical research suggesting mechanisms likely to underlie lithium's therapeutic actions including direct targets inositol monophosphatase and glycogen synthase kinase-3 (GSK-3) among others, as well as indirect actions including modulation of neurotrophic and neurotransmitter systems and circadian function. We follow with a discussion of current knowledge related to the pharmacogenetic underpinnings of effective lithium therapy in patients within this context. Progress in elucidation of genetic factors that may be involved in human response to lithium pharmacology has been slow, and there is still limited conclusive evidence for the role of a particular genetic factor. However, the development of new approaches such as genome-wide association studies (GWAS), and increased use of genetic testing and improved identification of mood disorder patients sub-groups will lead to improved elucidation of relevant genetic factors in the future. © 2014 Elsevier Inc.

Hair fibre is regarded as a unique mammalian feature with an important role for endothermy. Artificial selection for hair characteristics resulted in marked changes with regard to follicle number, type, distribution, growth and natural shedding. This review focuses on the fine fibre-producing South American camelids (SACs) and the relationship between their hair coat and thermoregulation. SACs have developed several special integumental characteristics. While the hair coat of the wild lamoids vicua (Vicugna vicugna) and guanaco (Lama guanicoe) is formed by two types of hair (the coarse outer guard hairs and a finer undercoat), the domesticated llamas (Lama glama) and alpaca (Lama pacos) exhibit variably double coat and predominantly single coat, respectively. The distribution of the hair coat across the body is not homogenous. Thermal windows with shorter hair or thinner skin can be identified at the ventral abdomen, axillary space and inside of the thighs (about 20% of the skin), thus allowing to modulate heat dissipation. In contrast to sheep wool, lamoid fibres are mainly medullated. The thermal conductance of summer pelage was higher than that of the winter fleece and highest for the axillar and lower flanks. Lamoids have developed behavioural strategies to modify heat loss by adopting specific postures according to ambient conditions by closing or opening the thermal windows. Energy savings of 67% attributed to posture were calculated. SACs have shown to be able to adapt to a broad range of different climatic conditions. The specific integumental characteristics of SACs indicate that they have developed adaptation mechanisms particularly suited for cooler climates. Accordingly, hyperthermia might become a problem in hot, humid areas outside of their original habitat. Several studies showed the beneficial effect of shearing against heat stress. In particular, fertility in males exposed to heat stress may be improved by shearing. Infrared thermography reveals that in shorn animals the heat is radiated across the entire body surface and is not restricted to the thermal windows. However, shearing also changes the conditions of the protective layer, resulting in a loss of thermal conductance that may result in adverse effects when animals are kept under cold temperatures. The length of residual fibre appears to be crucial in avoiding excessive heat loss in a cold environment, as demonstrated by shearing experiments with different shearing machines. There is, therefore, potential for welfare considerations to conflict with industrial demands for fibre length or homogenous quality. Copyright © The Animal Consortium 2009.

Hustert R.,University of Gottingen
Arthropod Structure and Development | Year: 2012

Miniaturization effects in the central nervous system (CNS) of a very small calchicid wasp, Encarsia formosa (0.6 mm long), are obvious for the overall morphology and at the level of axon sizes. Parasagittal sections show that most ganglia are fused and leave connectives only in the neck and the petiole. The thoracic complex is partly squeezed between muscles, enwraps cuticular apodemes and protrudes laterally into the coxae of legs. Somata of neurons are similar in size and form a multiple layer around large neuropile regions of the CNS. In TEM sections of connectives the range of axon diameters lies between 0.045 and 3.8 μm. Extremely small axon diameters below 0.1 μm are supposed to present spatial restrictions for ion channels and internal organelles. In theory, that can cause frequent spontaneous releases of action potentials (AP) which impede regular information transfer by normal APs. Therefore, axon sizes were studied in connectives between ganglia where longer distance information transfer requires action potentials even in the smallest axons. The diameters of many interganglionic axons below 0.08 μm contradict the theory. The luxury of large axon diameters exceeding 2-3 μm is reserved for several " giant" interneurons in the thoracic and in the abdominal ganglion complex. They should belong to rapid sensory alerting systems. The largest, a bilateral pair in the abdominal CNS, could integrate afferents from long wind sensitive hairs on the abdomen. © 2012 Elsevier Ltd.

Sauermann N.,University of Gottingen | Gonzalez M.J.,University of Gottingen | Ackermann L.,University of Gottingen
Organic Letters | Year: 2015

Expedient cobalt-catalyzed C-H alkynylation was achieved under exceedingly mild reaction conditions. Thus, chelation-assisted direct alkynylations of heteroarenes occurred with 1-bromoalkynes and ample substrate scope. The optimized catalytic system allowed for step-economical C-H functionalizations with a mild base K2CO3 at reaction temperatures as low as 25 °C. © 2015 American Chemical Society.

Thoms S.,University of Gottingen
Open Biology | Year: 2015

Peroxisomes are capable of importing folded and oligomeric proteins. However, it is a matter of dispute whether oligomer import by peroxisomes is the exception or the rule. Here, I argue for a clear distinction between homo-oli-gomeric proteins that are essentially peroxisomal, and dually localized hetero-oligomers that access the peroxisome by piggyback import, localizing there in limited number, whereas the majority remain in the cytosol. Homooligomeric proteins comprise the majority of all peroxisomal matrix proteins. There is evidence that binding by Pex5 in the cytosol can regulate their oligomerization state before import. The hetero-oligomer group is made up of superoxide dismutase and lactate dehydrogenase. These proteins have evolved mechanisms that render import inefficient and retain the majority of proteins in the cytosol. © 2015 The Authors.

Farina D.,University of Gottingen | Negro F.,University of Gottingen
Exercise and Sport Sciences Reviews | Year: 2015

In considering the role of common synaptic input to motor neurons in force control, we hypothesize that the effective neural drive to muscle replicates the common input and is, thus, the main determinant of force production. Such a perspective argues against a significant role for motor unit synchronization in force control. © 2014 by the American College of Sports Medicine.

Mayrhofer R.,University of Gottingen | Waldmann M.R.,University of Gottingen
Cognition | Year: 2014

The question how agent and patient roles are assigned to causal participants has largely been neglected in the psychological literature on force dynamics. Inspired by the linguistic theory of Dowty (1991), we propose that agency attributions are based on a prototype concept of human intervention. We predicted that the number of criteria a participant in a causal interaction shares with this prototype determines the strength of agency intuitions. We showed in two experiments using versions of Michotte's (1963) launching scenarios that agency intuitions were moderated by manipulations of the context prior to the launching event. Altering features, such as relative movement, sequence of visibility, and self-propelled motion, tended to increase agency attributions to the participant that is normally viewed as patient in the standard scenario. © 2014 Elsevier B.V.

Leonforte F.,University of Gottingen | Muller M.,University of Gottingen
Macromolecules | Year: 2015

The response of adaptive multicomponent polymer brushes to chemically patterned top surfaces as a function of the solvent quality and grafting density of the brushes and for applied patterns is studied by molecular dynamics simulations of a coarse-grained implicit-solvent model with soft, nonbonded interactions. The model is developed in order to address experimentally relevant, large invariant degrees of polymerization, and nonbonded interactions are expressed via a third-order (virial) expansion of the equation of state. The choice of interaction parameters mimics PAA-b-PS diblock copolymer brushes and PAA/PS mixed brushes. The role of the geometry and scale of the surface pattern is explored and related to the response of the spontaneously assembled morphologies of the unconfined brushes. © 2014 American Chemical Society.

Peter T.,University of Gottingen | Plonka G.,University of Gottingen
Inverse Problems | Year: 2013

We derive a new generalization of Prony's method to reconstruct M-sparse expansions of (generalized) eigenfunctions of linear operators from only suitable values in a deterministic way. The proposed method covers the well-known reconstruction methods for M-sparse sums of exponentials as well as for the interpolation of M-sparse polynomials by using special linear operators in . Further, we can derive new reconstruction formulas for M-sparse expansions of orthogonal polynomials using the Sturm-Liouville operator. The method is also applied to the recovery of M-sparse vectors in finite-dimensional vector spaces. © 2013 IOP Publishing Ltd.

Polania R.,University of Gottingen | Nitsche M.A.,University of Gottingen | Paulus W.,University of Gottingen
Human Brain Mapping | Year: 2011

Transcranial direct current stimulation (tDCS) is a noninvasive brain stimulation technique that alters cortical excitability and activity in a polarity-dependent way. Stimulation for few minutes has been shown to induce plastic alterations of cortical excitability and to improve cognitive performance. These effects might be caused by stimulation-induced alterations of functional cortical network connectivity. We aimed to investigate the impact of tDCS on cortical network function through functional connectivity and graph theoretical analysis. Single recordings in healthy volunteers with 62 electroencephalography channels were acquired before and after 10 min of facilitatory anodal tDCS over the primary motor cortex (M1), combined with inhibitory cathodal tDCS of the contralateral frontopolar cortex, in resting state and during voluntary hand movements. Correlation matrices containing all 62 pairwise electrode combinations were calculated with the synchronization likelihood (SL) method and thresholded to construct undirected graphs for the θ, α, β, low-γ and high-γ frequency bands. SL matrices and undirected graphs were compared before and after tDCS. Functional connectivity patterns significantly increased within premotor, motor, and sensorimotor areas of the stimulated hemisphere during motor activity in the 60-90 Hz frequency range. Additionally, tDCS-induced significant intrahemispheric and interhemispheric connectivity changes in all the studied frequency bands. In summary, we show for the first time evidence for tDCS-induced changes in brain synchronization and topological functional organization. © 2010 Wiley-Liss, Inc.

Goerigk M.,University of Gottingen | Schobel A.,University of Gottingen
Computers and Operations Research | Year: 2013

The periodic event scheduling problem (PESP), in which events have to be scheduled repeatedly over a given period, is a complex and well-known discrete problem with numerous real-world applications. The most prominent of them is to find periodic timetables in public transport. Although even finding a feasible solution to the PESP is NP-hard, recent achievements demonstrate the applicability and practicability of the periodic event scheduling model. In this paper we propose different approaches to improve the modulo network simplex algorithm (Nachtigall and Opitz, 2008 [17]), which is a powerful heuristic for the PESP problem, by exploiting improved search methods in the modulo simplex tableau and larger classes of cuts to escape from the many local optima. Numerical experiments on large-scale railway instances show that our algorithms not only perform better than the original method, but even outperform a state-of-the-art commercial MIP solver. © 2012 Elsevier Ltd.

Meyer A.C.,University of Gottingen | Moser T.,University of Gottingen
Current Opinion in Otolaryngology and Head and Neck Surgery | Year: 2010

Purpose of Review For the perception of sound, acoustic signals need to be encoded into a neuronal code. This takes place at the inner hair cells of the organ of Corti and the afferent fibres of the auditory nerve. We will review the current knowledge of the anatomy and function of these elements as well as their connection-formed by the afferent inner hair cell synapse. Recent Findings: Depending on their tonotopic location, inner hair cells are innervated by 5-30 dendrites of spiral ganglion neurons. Electrophysiological recordings from single fibres demonstrate-apart from a high-frequency selectivity-a pronounced heterogeneity in their response to sound of varying intensity. The source as well as the function of this heterogeneity is not well understood, but recent publications have suggested several mechanisms, including variations in the presynaptic Ca influx and subsequent transmitter release, the postsynaptic sensitivity to neurotransmitter and electrical as well as anatomical variability of single fibres. These mechanisms might act together to expand the dynamic range of sound that can be encoded. Summary: Classical studies as well as recent publications demonstrate that sound encoding at the inner hair cell afferent synapse involves mechanisms leading to tonotopic frequency separation and distribution of intensity coding over many neuronal channels. © 2010 Wolters Kluwer Health | Lippincott Williams & Wilkins.

Moser T.,University of Gottingen | Predoehl F.,University of Gottingen | Starr A.,University of California at Irvine
Otology and Neurotology | Year: 2013

OBJECTIVE: To review new insights into the pathophysiology of sensorineural hearing impairment. Specifically, we address defects of the ribbon synapses between inner hair cells and spiral ganglion neurons that cause auditory synaptopathy. DATA SOURCES AND STUDY SELECTION: Here, we review original publications on the genetics, animal models, and molecular mechanisms of hair cell ribbon synapses and their dysfunction. CONCLUSION: Hair cell ribbon synapses are highly specialized to enable indefatigable sound encoding with utmost temporal precision. Their dysfunctions, which we term auditory synaptopathies, impair audibility of sounds to varying degrees but commonly affect neural encoding of acoustic temporal cues essential for speech comprehension. Clinical features of auditory synaptopathies are similar to those accompanying auditory neuropathy, a group of genetic and acquired disorders of spiral ganglion neurons. Genetic auditory synaptopathies include alterations of glutamate loading of synaptic vesicles, synaptic Ca influx or synaptic vesicle turnover. Acquired synaptopathies include noise-induced hearing loss because of excitotoxic synaptic damage and subsequent gradual neural degeneration. Alterations of ribbon synapses likely also contribute to age-related hearing loss. © 2013, Otology &Neurotology, Inc.

Kiel S.,University of Gottingen
Proceedings. Biological sciences / The Royal Society | Year: 2015

The origin and evolution of the faunas inhabiting deep-sea hydrothermal vents and methane seeps have been debated for decades. These faunas rely on a local source of sulfide and other reduced chemicals for nutrition, which spawned the hypothesis that their evolutionary history is independent from that of photosynthesis-based food chains and instead driven by extinction events caused by deep-sea anoxia. Here I use the fossil record of seep molluscs to show that trends in body size, relative abundance and epifaunal/infaunal ratios track current estimates of seawater sulfate concentrations through the last 150 Myr. Furthermore, the two main faunal turnovers during this time interval coincide with major changes in seawater sulfate concentrations. Because sulfide at seeps originates mostly from seawater sulfate, variations in sulfate concentrations should directly affect the base of the food chain of this ecosystem and are thus the likely driver of the observed macroecologic and evolutionary patterns. The results imply that the methane-seep fauna evolved largely independently from developments and mass extinctions affecting the photosynthesis-based biosphere and add to the growing body of evidence that the chemical evolution of the oceans had a major impact on the evolution of marine life. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

Hesse R.,University of Gottingen | Luke D.R.,University of Gottingen
SIAM Journal on Optimization | Year: 2013

We consider projection algorithms for solving (nonconvex) feasibility problems in Euclidean spaces. Of special interest are the method of alternating projections (AP) and the Douglas-Rachford algorithm (DR). In the case of convex feasibility, firm nonexpansiveness of projection mappings is a global property that yields global convergence of AP and for consistent problems DR. A notion of local subfirm nonexpansiveness with respect to the intersection is introduced for consistent feasibility problems. This, together with a coercivity condition that relates to the regularity of the collection of sets at points in the intersection, yields local linear convergence of AP for a wide class of nonconvex problems and even local linear convergence of nonconvex instances of the DR algorithm. © 2013 Society for Industrial and Applied Mathematics.

Flot J.-F.,French Natural History Museum | Flot J.-F.,University of Gottingen
Molecular Ecology Resources | Year: 2010

The program phase is widely used for Bayesian inference of haplotypes from diploid genotypes; however, manually creating phase input files from sequence alignments is an error-prone and time-consuming process, especially when dealing with numerous variable sites and/or individuals. Here, a web tool called seqphase is presented that generates phase input files from fasta sequence alignments and converts phase output files back into fasta. During the production of the phase input file, several consistency checks are performed on the dataset and suitable command line options to be used for the actual phase data analysis are suggested. seqphase was written in perl and is freely accessible over the Internet at the address © 2009 Blackwell Publishing Ltd.

Li J.,University of Gottingen | Ackermann L.,University of Gottingen
Chemistry - A European Journal | Year: 2015

Cobalt-catalyzed C-H arylations enabled the synthesis of biaryl tetrazoles, which are key structural motifs in antihypertensive angiotensin-II-receptor blockers. Thus, weakly-coordinating benzamides were employed for step-economical C-H arylations with ample scope. Further, a low-valent NHC complex enabled first cobalt-catalyzed C-H functionalization by tetrazole assistance. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Zeisberg M.,University of Gottingen | Zeisberg E.M.,University of Gottingen
Kidney International | Year: 2015

Among gliptins, linagliptin is unique, because decreased glomerular filtration rate does not require dose reduction. Linagliptin was originally developed to lower blood glucose by inhibiting dipeptidyl peptidase-4 (DPP-4). However, DPP-4 has numerous additional substrates, and thus gliptins possess a vast range of additional off-target effects. Shi et al. report that linagliptin directly targets interaction of DPP-4 with integrin β1, preventing endothelial-mesenchymal transition and ultimately renal fibrosis, providing additional rationale for use of linagliptin in diabetic nephropathy. © 2015 International Society of Nephrology.

Infection with hepatitis C virus (HCV) primarily causes chronic liver disease with characteristic histopathologic features, including hepatic steatosis. Moreover, chronic hepatitis C is also closely related to insulin resistance (IR) and an increased risk of type 2 diabetes mellitus (DM). This review summarizes the available clinical evidence for a linkage of chronic HCV infection and developing IR or DM that comprises (i) retro- and prospective clinical studies, (ii) the excess risk of chronic hepatitis C patients to develop DM compared to hepatitis B patients, (iii) a preferential relationship of IR with HCV type-1, -2 or -4 infections, (iv) a correlation between IR, viral load and responsiveness to antiviral treatment and (v) a decreased incidence of DM in chronic hepatitis C after sustained virological response. This review further refers to the clinical evidence of a preferential relationship between hepatic steatosis and HCV type-3 infection, and that two distinct genotype-specific pathogenic mechanisms underlie steatosis in hepatitis C. In HCV type-3 infections, steatosis is related to viral load but not to metabolic factors, and, thus, is termed 'viral steatosis'. In HCV type-1, -2 or -4 infections, steatosis appears to be secondary to IR and regarded as 'metabolic steatosis'. In conclusion, multiple lines of clinical evidence support a linkage of HCV infection and both hepatic carbohydrate and lipid metabolism. The extent to which targeting the host's metabolism by drugs or by lifestyle change translates into an improvement of health or in a better response to interferon-α will provide further valuable insights into virus-host interactions, and is topic which is currently addressed in clinical studies. Copyright © 2010 S. Karger AG, Basel.

Naz N.,University of Gottingen
Shock (Augusta, Ga.) | Year: 2013

Ferritin L (FTL) and ferritin H (FTH) subunits are responsible for intracellular iron storage. Serum ferritin levels are not only dependant on body iron stores. Aims of the present study are to demonstrate nature, source, and major regulatory mediators of serum ferritin in an animal model of acute-phase (AP) response. Animals (rats, wild-type [WT] mice, and interleukin [IL]-6ko mice) were injected with turpentine oil (TO) intra-muscularity to induce a sterile abscess and sacrificed at different time points afterward. Rat hepatocytes were isolated for cell culture and, after reaching confluence, stimulated with major AP cytokines to induce AP conditions. We found a significantly increased expression of both ferritin subunits in liver at mRNA and protein levels during AP response. In the serum of both control and TO-injected rats, only FTL was detectable by Western blotting, whereas no increase in serum FTL was measured by Western blot or enzyme-linked immunosorbent assay. An increase in protein expression of FTL and FTH was observed in lysates of rat hepatocytes after treatment with IL-6, IL-1β, and tumor necrosis factor-α; however, only FTL was increasingly released into supernatant. In both TO-injected rats and WT mice, a dramatic increase in serum IL-6 levels was observed, along with an increased amount of hepatic ferritin subunits. However, an increase of hepatic FTL but not of FTH protein expression was observed in IL-6ko mice after TO injection. Our data demonstrate that FTL is the only rat serum ferritin whose release into circulation from the hepatocytes is increased by the effect of AP cytokines (e.g., IL-6). In contrast, FTH expression is intracellular in both under physiological and AP conditions.

D'Adderio M.,University of Gottingen | Moci L.,University of Rome La Sapienza
Journal of Combinatorial Theory. Series A | Year: 2013

We introduce the notions of arithmetic colorings and arithmetic flows over a graph with labelled edges, which generalize the notions of colorings and flows over a graph. We show that the corresponding arithmetic chromatic polynomial and arithmetic flow polynomial are given by suitable specializations of the associated arithmetic Tutte polynomial, generalizing classical results of Tutte (1954) [9]. © 2012 Elsevier Inc.

Straube S.,University of Gottingen
Cochrane database of systematic reviews (Online) | Year: 2010

BACKGROUND: Gabapentin is an antiepileptic drug, also used in the treatment of neuropathic pain, which is the subject of a Cochrane review, currently under revision. Its efficacy in treating established acute postoperative pain has not been demonstrated. OBJECTIVES: To assess the efficacy and safety of single dose oral gabapentin compared with placebo in established acute postoperative pain using methods that permit comparison with other analgesics. SEARCH STRATEGY: We searched Cochrane CENTRAL, MEDLINE, EMBASE, and the Oxford Pain Relief Database. Additional studies were sought from reference lists of retrieved articles and reviews. Clinical trials databases were searched for unpublished studies; clinical trial reports of several unpublished studies have been made public following litigation in the US. SELECTION CRITERIA: Single oral dose, randomised, double-blind, placebo-controlled trials of gabapentin for relief of established moderate to severe postoperative pain in adults. DATA COLLECTION AND ANALYSIS: Studies were assessed for methodological quality and data extracted by two review authors independently. Numbers of participants with at least 50% of maximum possible total pain relief (TOTPAR) or summed pain intensity difference (SPID) with gabapentin or placebo were calculated and used to derive relative benefit (RB) or risk (RR), and number-needed-to-treat-to-benefit (NNT). Numbers of participants using rescue medication, and time to its use, were sought as additional measures of efficacy. Information on adverse events and withdrawals was collected. MAIN RESULTS: Four unpublished studies met inclusion criteria; in three, participants had pain following dental surgery, and one followed major orthopaedic surgery; 177 participants were treated with a single dose of gabapentin 250 mg, 21 with gabapentin 500 mg, and 172 with placebo. At least 50% pain relief over 6 hours was achieved by 15% with gabapentin 250 mg and 5% with placebo; giving a RB of 2.5 (95% CI 1.2 to 5.0) and an NNT of 11 (6.4 to 35). Significantly fewer participants needed rescue medication within 6 hours with gabapentin 250 mg than with placebo; NNT to prevent use 5.8. About one third of participants reported adverse events with both gabapentin 250 mg and placebo. No serious adverse events occurred with gabapentin. AUTHORS' CONCLUSIONS: Gabapentin 250 mg is statistically superior to placebo in the treatment of established acute postoperative pain, but the NNT of 11 for at least 50% pain relief over 6 hours with gabapentin 250 mg is of limited clinical value and inferior to commonly used analgesics. Gabapentin 250 mg is not clinically useful as a stand-alone analgesic in established acute postoperative pain, though this is probably the first demonstration of analgesic effect of an antiepileptic in established acute pain.

Luke D.R.,University of Gottingen
Journal of Mathematical Imaging and Vision | Year: 2013

We present an analysis of sets of matrices with rank less than or equal to a specified number s. We provide a simple formula for the normal cone to such sets, and use this to show that these sets are prox-regular at all points with rank exactly equal to s. The normal cone formula appears to be new. This allows for easy application of prior results guaranteeing local linear convergence of the fundamental alternating projection algorithm between sets, one of which is a rank constraint set. We apply this to show local linear convergence of another fundamental algorithm, approximate steepest descent. Our results apply not only to linear systems with rank constraints, as has been treated extensively in the literature, but also nonconvex systems with rank constraints. © 2012 The Author(s).

Brockmann K.,University of Gottingen
Current Neurology and Neuroscience Reports | Year: 2013

Episodic dyskinetic movement disorders are a heterogeneous group of rare conditions. Paroxysmal dyskinesias constitute the core of this group and usually exhibit normal interepisodic neurologic findings. Contrariwise, episodic dyskinesias occur as a particular feature of complex chronic neurologic disorders. Conjunction of accurate phenotyping with up-to-date methods of molecular genetics recently provided remarkable new insights concerning the genetic causes of episodic dyskinesia. The identification of heterozygous mutations in the PRRT2 gene in paroxysmal kinesigenic dyskinesia as well as in benign familial infantile seizures linked episodic movement disorders with epilepsy. Alternating hemiplegia of childhood, the prototype of a chronic multisystem disease with episodic dyskinesia as a clinical hallmark, was recently found to be caused by heterozygous de novo mutations in the ATP1A3 gene. The clinical spectra of PRRT2 as well as of ATP1A3 mutations are still expanding. This review summarizes new genetic findings and clinical aspects in episodic dyskinesias. © 2013 Springer Science+Business Media New York.

Digel C.,University of Gottingen | Riede J.O.,University of Gottingen | Brose U.,University of Gottingen
Oikos | Year: 2011

The distributions of body masses and degrees (i.e. the number of trophic links) across species are key determinants of food-web structure and dynamics. In particular, allometric degree distributions combining both aspects in the relationship between degrees and body masses are of critical importance for the stability of these complex ecological networks. They describe decreases in vulnerability (i.e. the number of predators) and increases in generality (i.e. the number of prey) with increasing species' body masses. We used an entirely new global body-mass database containing 94 food webs from four different ecosystem types (17 terrestrial, 7 marine, 54 lake, 16 stream ecosystems) to analyze (1) body mass distributions, (2) cumulative degree distributions (vulnerability, generality, linkedness), and (3) allometric degree distributions (e.g. generality - body mass relationships) for significant differences among ecosystem types. Our results demonstrate some general patterns across ecosystems: (1) the body masses are often roughly log-normally (terrestrial and stream ecosystems) or multi-modally (lake and marine ecosystems) distributed, and (2) most networks exhibit exponential cumulative degree distributions except stream networks that most often possess uniform degree distributions. Additionally, with increasing species body masses we found significant decreases in vulnerability in 70% of the food webs and significant increases in generality in 80% of the food webs. Surprisingly, the slopes of these allometric degree distributions were roughly three times steeper in streams than in the other ecosystem types, which implies that streams exhibit a more pronounced body mass structure. Overall, our analyses documented some striking generalities in the body-mass (allometric degree distributions of generality and vulnerability) and degree structure (exponential degree distributions) across ecosystem types as well as surprising exceptions (uniform degree distributions in stream ecosystems). This suggests general constraints of body masses on the link structure of natural food webs irrespective of ecosystem characteristics. © 2011 The Authors.

Waldmann I.,University of Gottingen | Spillner C.,University of Gottingen | Kehlenbach R.H.,University of Gottingen
Journal of Cell Science | Year: 2012

Translocation of transport complexes across the nuclear envelope is mediated by nucleoporins, proteins of the nuclear pore complex that contain phenylalanine-glycine (FG) repeats as a characteristic binding motif for transport receptors. CRM1 (exportin 1), the major export receptor, forms trimeric complexes with RanGTP and proteins containing nuclear export sequences (NESs). We analyzed the role of the nucleoporin-like protein 1, NLP1 (also known as hCG1 and NUPL2) in CRM1-dependent nuclear transport. NLP1, which contains many FG repeats, localizes to the nuclear envelope and could also be mobile within the nucleus. It promotes the formation of complexes containing CRM1 and RanGTP, with or without NES-containing cargo proteins, that can be dissociated by RanBP1 and/or the cytoplasmic nucleoporin Nup214. The FG repeats of NLP1 do not play a major role in CRM1 binding. Overexpression of NLP1 promotes CRM1-dependent export of certain cargos, whereas its depletion by small interfering RNAs leads to reduced export rates. Thus, NLP1 functions as an accessory factor in CRM1-dependent nuclear protein export. © 2012.

Adiabatic compressibility data and principal dielectric relaxation times for aqueous solutions of 1:1 and 2:1 valent electrolytes are evaluated to yield their relative molal shifts B and B, respectively, at low solute concentration. Cationic (Bx) and anionic (Bx) contributions to these quantities are calculated and compared to one another. For some ions also the correspondent relative molal shifts (Bm in the intramolecular proton magnetic relaxation rates are considered. Clear correlations between Bκ values are found for most series of ions. Within the series of halide ions, for example, Bκ increases, whereas Bd decreases with anion radius. For large hydrophobic cations the opposite is true; that is, Bκ increases and Bd decreases with molar volume of ion. In general, the magnitudes |Bk in the changes of the compressibility coefficient are smaller than in the shifts of the dielectric relaxation time. The situation is more complicated with dielectrically saturated small ions. Since the apparently irrotationally bound water molecules around such ions do not contribute to the dielectric spectra by reorientation, comparison of compressibility changes with changes in the proton magnetic relaxation rate rather than in the dielectric relaxation time is more appropriate. Some composite ions, such as BF4O, show special features which can, however, be explained by a nonspherical charge distribution at the ion surface. © 2013 American Chemical Society.

Sanders K.,University of Gottingen
Communications in Mathematical Physics | Year: 2010

We prove that the singularity structure of all n-point distributions of a state of a generalised real free scalar field in curved spacetime can be estimated if the two-point distribution is of Hadamard form. In particular this applies to the free field and the result has applications in perturbative quantum field theory, showing that the class of all Hadamard states is the state space of interest. In our proof we assume that the field is a generalised free field, i.e. that it satisfies scalar (c-number) commutation relations, but it need not satisfy an equation of motion. The same arguments also work for anti-commutation relations and for vector-valued fields. To indicate the strengths and limitations of our assumption we also prove the analogues of a theorem by Borchers and Zimmermann on the self-adjointness of field operators and of a weak form of the Jost-Schroer theorem. The original proofs of these results make use of analytic continuation arguments. In our case no analyticity is assumed, but to some extent the scalar commutation relations can take its place. © The Author(s) 2009.

Wirths O.,University of Gottingen | Bayer T.A.,University of Gottingen
Life Sciences | Year: 2012

Aims: In the present review we summarize current knowledge on the concept of intraneuronal Aβ as a determinant for neuron loss and other pathological alterations in transgenic models for Alzheimer disease. Main methods: We discuss the use of transgenic mouse and non-vertebrate transgenic models accumulating intracellular Aβ peptides and their impact on the ongoing discussion. Key findings: Intraneuronal Aβ accumulation in transgenic models is intimately linked to pathological alterations including neuron loss. One of the technical caveats for visualizing intraneuronal Aβ is the antibody used to unequivocally demonstrate its presence. Very often antibodies were used that recognize both Aβ and APP, leading to false positive results due to misinterpretation. Significance: Whereas a clear relationship between intraneuronal Aβ accumulation and neuron loss is evident in transgenic mouse models it remains an unresolved issue whether the concept of intraneuronal Aβ can be integrated into the human pathology as well. © 2012 Elsevier Inc. All rights reserved.

Kroner-Herwig B.,University of Gottingen
Current Pain and Headache Reports | Year: 2013

All relevant databases (i.e., Pubmed, PsycINFO) were searched for studies published in 2011-2013 focusing on the association of behavioral, cognitive-emotional, and psychosocial factors with recurrent headache in children and adolescents. Only 3 studies were found dealing with psychological intervention for headache; only 2 of them presented empirical data but were not conducted as a RCT. Eleven studies (clinical and population) were concerned with the association of psychosocial factors, dysfunctional psychological traits, and symptoms and headache or examined certain pain features (triggers, course over time, disability). Most studies were interested in the association of cognitive-emotional symptoms (e.g., internalizing symptoms, anxiety) and their relation to headache, including a meta-analysis. In nearly all studies, a close bond between negative affectivity and headache, especially migraine, was revealed. © 2013 Springer Science+Business Media New York.

Werz D.B.,University of Gottingen
Methods in Molecular Biology | Year: 2012

For all carbohydrate microarrays, two important prerequisites are necessary: the carbohydrate of interest has to be obtained either by isolation from natural sources, enzymatic or chemical synthesis; an immobilization of the carbohydrate at the surface of the chip has to be achieved. This chapter provides a very brief overview of the chemical synthesis of carbohydrates (creation of building blocks, assembly, and deprotection) and of immobilization techniques. Numerous methods are known to construct oligosaccharides by chemical methods. A typical monosaccharide building block, used in oligosaccharide assembly, is equipped with different protecting groups that mask the hydroxyl and amine groups. In general, a good leaving group at the anomeric center that can easily be activated is mandatory; especially trichloroacetimidates, phosphates, and thioethers have been widely used for the creation of glycosidic bonds. After the complete assembly of the oligosaccharide, a global deprotection of all permanent protecting groups affords the desired target structure with free hydroxyl groups. Linkers, which were introduced during the synthesis, must often be modified at the end to create appropriate functionalities for surface immobilization. © 2012 Springer Science+Business Media, LLC.

Sowa H.,University of Gottingen
Acta Crystallographica Section A: Foundations of Crystallography | Year: 2012

All homogeneous sphere packings and all interpenetrating layers of spheres were derived that can be realized in the ten orthorhombic trivariant lattice complexes belonging to the space groups of crystal class mmm without mirror symmetry. Altogether, sphere packings of 186 different types have been found; the maximal inherent symmetry is orthorhombic for 124 of these types. In addition, ten types of interpenetrating sphere packings were detected, and in three lattice complexes interpenetrating 6 3 nets occur. © 2012 International Union of Crystallography Printed in Singapore-all rights reserved.

Fehl K.,University of Gottingen | van der Post D.J.,University of Gottingen | Semmann D.,University of Gottingen
Ecology Letters | Year: 2011

The ubiquity of cooperation in nature is puzzling because cooperators can be exploited by defectors. Recent theoretical work shows that if dynamic networks define interactions between individuals, cooperation is favoured by natural selection. To address this, we compare cooperative behaviour in multiple but independent repeated games between participants in static and dynamic networks. In the latter, participants could break their links after each social interaction. As predicted, we find higher levels of cooperation in dynamic networks. Through biased link breaking (i.e. to defectors) participants affected their social environment. We show that this link-breaking behaviour leads to substantial network clustering and we find primarily cooperators within these clusters. This assortment is remarkable because it occurred on top of behavioural assortment through direct reciprocity and beyond the perception of participants, and represents a self-organized pattern. Our results highlight the importance of the interaction between ecological context and selective pressures on cooperation. © 2011 Blackwell Publishing Ltd/CNRS.

Thorn A.,University of Gottingen | Dittrich B.,University of Gottingen | Sheldrick G.M.,University of Gottingen
Acta Crystallographica Section A: Foundations of Crystallography | Year: 2012

The rigid-bond model [Hirshfeld (1976). Acta Cryst. A32, 239-244] states that the mean-square displacements of two atoms are equal in the direction of the bond joining them. This criterion is widely used for verification (as intended by Hirshfeld) and also as a restraint in structure refinement as suggested by Rollett [Crystallographic Computing (1970), edited by F. R. Ahmed et al., pp. 167-181. Copenhagen: Munksgaard]. By reformulating this condition, so that the relative motion of the two atoms is required to be perpendicular to the bond, the number of restraints that can be applied per anisotropic atom is increased from about one to about three. Application of this condition to 1,3-distances in addition to the 1,2-distances means that on average just over six restraints can be applied to the six anisotropic displacement parameters of each atom. This concept is tested against very high resolution data of a small peptide and employed as a restraint for protein refinement at more modest resolution (e.g. 1.7 Å). © 2012 International Union of Crystallography Printed in Singapore - all rights reserved.

Sulieman S.,University of Gottingen
Plant Signaling and Behavior | Year: 2011

The ability to regulate the rates of metabolic processes in response to changes in the internal and/or externa l environment is a fundamental feature which is inherent in all organisms. This adaptability is necessary for conserving the stability of the intercellular environment (homeostasis) which is essential for maintaining an efficient functional state in the organism. Symbiotic nitrogen fixation in legumes is an important process which establishes from the complex interaction between the host plant and microorganism. This process is widely believed to be regulated by the host plant nitrogen demand through a whole plant n feedback mechanism in particular under unfavorable conditions. This mechanism is probably triggered by the impact of shoot-borne, phloem-delivered substances. The precise mechanism of the potential signal is under debate, however, the whole phenomenon is probably related to a constant amino acid cycling within the plant, thereby signaling the shoot nitrogen status. Recent work indicating that there may be a flow of nitrogen to bacteroids is discussed in light of hypothesis that such a flow may be important to nodule function. Large amount of γ-aminobutyric acid (GABA) are cycled through the root nodules of the symbiotic plants. in this paper some recent evidence concerning the possible role of GABA in whole-plant-based upregulation of symbiotic nitrogen fixation will be reviewed. © 2011 Landes Bioscience.

Forest fragmentation can negatively affect tropical epiphyte diversity, but the processes leading to such impoverishment are insufficiently understood. Due to a lack of experimental studies, the relative influence of dispersal constraints vs. growth conditions remains particularly controversial. This paper addresses the fate of late juvenile and adult vascular epiphytes in response to severe forest disturbance in montane southern Ecuador. Plant growth and survival on trunks and lower branches of isolated remnant trees was studied for the first three years following clear-cutting. Overall epiphyte mortality was substantially increased on remnant trees (72% over 3 years) relative to undisturbed forest (11%). Mortality on remnant trees was higher during the first year (52%) than during the second (20%) and third year (26%). Pteridophytes and dicots suffered higher losses than monocots. Plants surviving on remnant trees generally showed a marked negative growth regarding maximum leaf length, whereas the annual increment in leaf number varied more strongly among taxa (families). The present study provides the first field-experimental evidence for the adverse effects of forest disturbance on the performance of later, well-established life stages of vascular epiphytes. The results suggest that growth conditions may often be a more important predictor of epiphyte diversity in disturbed habitats than dispersal constraints. Similar plant responses can be expected to occur along forest edges. Therefore, the retention of scattered green trees, narrow strips or small fragments of forest are unlikely to be sufficient management tools for the conservation of epiphyte diversity in tropical landscapes. Waldfragmentierung kann tropische Epiphytendiversität beeinträchtigen, doch die zugrundeliegenden Prozesse sind unklar. Nicht zuletzt durch das Fehlen experimenteller Studien bleibt insbesondere der Einfluss von Ausbreitungslimitierungen gegenüber Wachstumsbedingungen kontrovers. Die vorliegende Arbeit untersucht die Folgen einer Waldrodung für spätjuvenile und adulte Wuchsstadien vaskulärer Epiphyten in den Anden Südecuadors. Hierzu wurde das Schicksal individueller Pflanzen auf Stämmen und niedrigen Ästen isolierter Reliktbäume über die ersten drei Jahre nach der Waldrodung verfolgt. Epiphyten auf Reliktbäumen zeigten deutlich höhere Sterblichkeitsraten (im Mittel 72% über drei Jahre) als in ungestörtem Wald (11%). Die Sterblichkeit auf Reliktbäumen war im ersten Jahr höher (52%) als im zweiten (20%) und dritten Jahr (26%). Pteridophyten und Zweikeimblättrige erlitten höhere Verluste als Einkeimblättrige. Auf Reliktbäumen überlebende Pflanzen zeigten allgemein ein deutlich negatives Wachstum hinsichtlich der maximalen Blattlänge. Hinsichtlich der jährlichen Zunahme der Blattzahl zeigte sich hingegen höhere Variabilität zwischen einzelnen Taxa (Familien). Diese Studie kann erstmalig freilandexperimentell den negativen Einfluss menschlicher Störung auf die Vitalität späterer Lebensstadien von Epiphyten belegen. Die Ergebnisse legen nahe, daß Wuchsbedingungen oft einen stärkeren Einfluss auf die Epiphytendiversität haben als Ausbreitungslimitierungen. Ähnliche Folgen für die Pflanzenvitalität sind entlang von Waldrändern zu erwarten. Reliktbäume, schmale Waldbänder und kleine Waldfragmente dürften daher kaum ausreichen, den Erhalt der Epiphytendiversität anthropomorpher tropischer Landschaften dauerhaft zu sichern. © 2010 Gesellschaft für Ökologie.

Clough Y.,University of Gottingen
Ecology | Year: 2012

The need to model and test hypotheses about complex ecological systems has led to a steady increase in use of path analytical techniques, which allow the modeling of multiple multivariate dependencies reflecting hypothesized causation and mechanisms. The aim is to achieve the estimation of direct, indirect, and total effects of one variable on another and to assess the adequacy of whole models. Path analytical techniques based on maximum likelihood currently used in ecology are rarely adequate for ecological data, which are often sparse, multi-level, and may contain nonlinear relationships as well as nonnormal response data such as counts or proportion data. Here I introduce a more flexible approach in the form of the joint application of hierarchical Bayes, Markov chain Monte Carlo algorithms, Shipley's d-sep test, and the potential outcomes framework to fit path models as well as to decompose and estimate effects. An example based on the direct and indirect interactions between ants, two insect herbivores, and a plant species demonstrates the implementation of these techniques, using freely available software. © 2012 by the Ecological Society of America.

Ballani F.,TU Bergakademie Freiberg | Schlather M.,University of Gottingen
Biometrika | Year: 2011

We present a construction principle for the spectral density of a multivariate extreme value distribution. It generalizes the pairwise beta model introduced in the literature recently and may be used to obtain new parametric models from lower dimensional spectral densities. We illustrate the flexibility of this new class of models and apply it to a wind speed dataset. © 2011 Biometrika Trust.

Friederich S.,University of Gottingen
Studies in History and Philosophy of Science Part B - Studies in History and Philosophy of Modern Physics | Year: 2013