University of Tbingen


University of Tbingen

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Wilhelm I.,University of Lübeck | Wilhelm I.,University of Tbingen | Metzkow-Meszaros M.,Martin Luther University of Halle Wittenberg | Knapp S.,Martin Luther University of Halle Wittenberg | And 2 more authors.
Developmental Science | Year: 2012

In striking contrast to adults, in children sleep following training a motor task did not induce the expected (offline) gain in motor skill performance in previous studies. Children normally perform at distinctly lower levels than adults. Moreover, evidence in adults suggests that sleep dependent offline gains in skill essentially depend on the pre-sleep level of performance. Against this background, we asked whether improving children's performance on a motor sequence learning task by extended training to levels approaching those of adults would enable sleep-associated gains in motor skill in this age group also. Children (4-6years) and adults (18-35years) performed on the motor sequence learning task (button-box task) before and after ∼2-hour retention intervals including either sleep (midday nap) or wakefulness. Whereas one group of children and adults, respectively, received the standard amount of 10 blocks of training before retention intervals of sleep or wakefulness, a further group of children received an extended training on 30 blocks (distributed across 3days). A further group of adults received a restricted training on only two blocks before the retention intervals. Children after standard training reached lowest performance levels, whereas in adults performance after standard training was highest. Children with extended training and adults after reduced training reached intermediate performance levels. Only at these intermediate performance levels did sleep induce significant gains in motor sequence skill, whereas performance did not benefit from sleep in the low-performing children or in the high-performing adults. Spindle counts in the post-training nap were correlated with performance gains at retrieval only in the adults benefitting from sleep. We conclude that, across age groups, sleep induces the most robust gain in motor skill at an intermediate pre-sleep performance level. In low-performing children sleep-dependent improvements in skill may be revealed only after enhancing the pre-sleep performance level by extended training. © 2012 Blackwell Publishing Ltd.

Bassi D.,University of Ferrara | Iryu Y.,Nagoya University | Nebelsick J.H.,University of Tbingen
Journal of Coastal Research | Year: 2012

The past environment is often reconstructed by measuring certain proxy data, such as changes in oxygen isotopes, taxonomic assemblages, and taphonomic signatures in a palaeoenvironmental archive (e.g., rhodoliths, corals, invertebrate shells, trees, ice cores, speleothems, etc.). Proxy analysis usually yields a record that has to be compared with present-day analogues to yield meaningful results. This also holds true for the interpretation of the palaeoenvironment of rhodolith deposits. The characteristics of Recent rhodoliths and the environments in which they are formed, thus, need to be known to interpret their fossil counterparts. The comparison of fossil and Recent rhodoliths and their environment is, however, not straightforward because the respective analytical methods applied to them are usually different and often difficult to reconcile. To reduce the uncertainties of this problem and to facilitate direct comparisons, we describe a number of analytical methods applied to fossil rhodoliths that can also be performed on Recent material. The analytical methods introduced here correspond to three different scales of analysis: (1) the outcrop scale as completed in field studies and the study of (2) isolated specimens and (3) thin sections in the laboratory. © 2012, the Coastal Education & Research Foundation (CERF).

Kucherenko Y.,University of Tbingen | Kucherenko Y.,Ukrainian Academy of Sciences | Zelenak C.,University of Tbingen | Eberhard M.,University of Tbingen | And 3 more authors.
Cellular Physiology and Biochemistry | Year: 2012

Pharmacological modification of protein kinase CK1 (casein kinase 1) has previously been shown to influence suicidal erythrocyte death or eryptosis, which is triggered by activation of Cl--sensitive Ca 2+-permeable cation channels. Ca2+ entering through those channels stimulates cell membrane scrambling and opens Ca2+-activated K+-channels resulting in KCl exit and thus cell shrinkage. The specific CK1-inhibitor D4476 (1 μM) blunted, whereas the specific CK1 αactivator pyrvinium pamoate (10 μM) enhanced cell membrane scrambling. The substances were at least partially effective through modification of cytosolic Ca2+-activity. The present study explored, whether pyrvinium pamoate indeed influences Cl--sensitive cation-channels in erythrocytes. As a result, removal of Cl-increased Fluo3-fluorescence (reflecting cytosolic Ca2+-activity), triggered cell membrane scrambling (apparent from annexin-V-binding), and decreased forward scatter (pointing to cell shrinkage). Pyrvinium pamoate significantly augmented the effect of Cl--removal on Fluo3 fluorescence and annexin-V-binding, but blunted the effect on forward scatter. According to whole cell patch clamp recording, Cl-removal activated a cation current, which was significantly enhanced by pyrvinium pamoate. Pyrvinium pamoate inhibited Ca 2+-activated K+-channels. Ca2+-ionophore ionomycin (1 μM) decreased forward scatter, an effect significantly blunted by pyrvinium pamoate. In conclusion, pyrvinium pamoate activates Cl --sensitive Ca2+-permeable cation channels with subsequent Ca2+-entry and inhibits Ca2+-activated K +-channels thus blunting the stimulating effect of Ca2+ on those channels, K+-exit and thus cell shrinkage. © 2012 S. Karger AG, Basel.

Schmelzbach C.,University of Potsdam | Schmelzbach C.,Free University of Berlin | Schmelzbach C.,ETH Zurich | Tronicke J.,University of Potsdam | And 2 more authors.
Water Resources Research | Year: 2012

Mapping hydrological parameter distributions in high resolution is essential to understand and simulate groundwater flow and contaminant transport. Of particular interest is surface-based ground-penetrating radar (GPR) reflection imaging in electrically resistive sediments because of the expected close link between the subsurface water content and the dielectric permittivity, which controls GPR wave velocity and reflectivity. Conventional tools like common midpoint (CMP) velocity analysis provide physical parameter models of limited resolution only. We present a novel reflection amplitude inversion workflow for surface-based GPR data capable of resolving the subsurface dielectric permittivity and related water content distribution with markedly improved resolution. Our scheme is an adaptation of a seismic reflection impedance inversion scheme to surface-based GPR data. Key is relative-amplitude-preserving data preconditioning including GPR deconvolution, which results in traces with the source-wavelet distortions and propagation effects largely removed. The subsequent inversion for the underlying dielectric permittivity and water content structure is constrained by in situ dielectric permittivity data obtained by direct-push logging. After demonstrating the potential of our novel scheme on a realistic synthetic data set, we apply it to two 2-D 100 MHz GPR profiles acquired over a shallow sedimentary aquifer resulting in water content images of the shallow (3-7m depth) saturated zone having decimeter resolution.© 2012. American Geophysical Union. All Rights Reserved.

Pollock D.,University of Tbingen | Pollock D.,ETH Zurich | Pollock D.,CSD Ingenieure AG | Cirpka O.A.,University of Tbingen
Water Resources Research | Year: 2012

We perform a salt tracer experiment, monitored by time-lapse electrical resistivity tomography, in a quasi-two-dimensional sandbox with the aim of determining the hydraulic conductivity distribution in the domain. We use sodium chloride as a tracer, together with cochineal red for visual monitoring. The time series of observed resistance for each electrode configuration is characterized by its temporal moments. We invert the mean arrival time of electrical potential perturbations and a few steady state hydraulic head measurements using the fully coupled hydrogeophysical approach recently introduced by Pollock and Cirpka (2010). This is the first application of the approach to experimental data. The results obtained show a reasonable agreement between the estimated hydraulic conductivity field and the pattern of the actual sandbox filling. Using this estimation, a transient simulation is performed to compute the propagation of the salt tracer plume through the sandbox. The latter is compared to pictures taken during the experiment. These results show an even better agreement, indicating that the lenses of different sand types are not entirely homogeneous and some unexpected preferential flow paths are present. We conclude that temporal moments of potential perturbations obtained during salt tracer tests provide a good basis for inferring the hydraulic conductivity distribution by fully coupled hydrogeophysical inversion.

Wnschel M.,University of Tbingen | Mller O.,University of Tbingen | Lo J.,University of Tbingen | Obloh C.,University of Tbingen | Wlker N.,University of Tbingen
Arthroscopy - Journal of Arthroscopic and Related Surgery | Year: 2010

Purpose: We investigated knee kinematics during simulated weight-bearing flexion and determined the effect of 3 different parameters of external tibial loading on the kinematics of the anterior cruciate ligament (ACL)intact and ACL-deficient knee. Methods: Ten human knee specimens were mounted on a dynamic knee simulator, and weight-bearing muscle-loaded knee flexions were simulated while a robotic/universal force sensor system was used to provide external tibial loads during the motion. Three different loading conditions were simulated: partial body weight only, an additional 50 N of anterior tibial force (ATD), or an additional 5 Nm of internal rotational tibial torque (IRT). After arthroscopic transection of the ACL, these 3 trials were repeated. The kinematics were measured with an ultrasonic measuring system for 3-dimensional motion analysis, and different loading and knee conditions were examined. Results: When the ACL was intact, ATD and IRT barely changed the anterior tibial translation. However, in the absence of the ACL, ATD significantly increased the anterior tibial translation by 5 mm whereas IRT did not. The application of IRT increased the internal tibial rotation of ACL-intact knees, but there was no difference in the internal rotation before and after transection of the ACL. Regardless of ACL status, the difference in the anterior tibial translation and the internal tibial rotation across different external tibial loadings was greater at lower flexion angles and gradually diminished with increasing flexion angles. Conclusions: We established an experimental protocol, incorporating a dynamic knee simulator and a robotic/universal force sensor system, to successfully measure the kinematics of the knee joint while applying external forces in weight-bearing flexion. Our findings suggest that, in muscle-loaded knee flexion, the ACL provides substantial resistance to externally applied ATD but not to IRT. Clinical Relevance: Information from this study allows us to better understand the function of the ACL and, hence, treatment of injuries to this important stabilizing ligament. © 2010 Arthroscopy Association of North America.

Lang F.,University of Tbingen | Lang F.,University of Tübingen | Lang E.,University of Tbingen | Fller M.,University of Tbingen
Transfusion Medicine and Hemotherapy | Year: 2012

Suicidal erythrocyte death (eryptosis) is characterized by cell shrinkage, cell membrane blebbing, and cell membrane phospholipid scrambling with phosphatidylserine exposure at the cell surface. Eryptotic cells adhere to the vascular wall and are rapidly cleared from circulating blood. Eryptosis is stimulated by an increase in cytosolic Ca 2+ activity, ceramide, hyperosmotic shock, oxidative stress, energy depletion, hyperthermia, and a wide variety of xenobiotics and endogenous substances. Inhibitors of eryptosis include erythropoietin and nitric oxide. Enhanced eryptosis is observed in diabetes, renal insufficiency, hemolytic uremic syndrome, sepsis, mycoplasma infection, malaria, iron deficiency, sickle cell anemia, beta-thalassemia, glucose-6-phosphate dehydrogenase-(G6PD) deficiency, hereditary spherocytosis, paroxysmal nocturnal hemoglobinuria, Wilson's disease, myelodysplastic syndrome, and phosphate depletion. Eryptosis is further enhanced in gene-targeted mice with deficient annexin 7, cGMP-dependent protein kinase type I (cGKI), AMP-activated protein kinase (AMPK), anion exchanger 1 (AE1), adenomatous polyposis coli (APC), and Klotho, as well as in mouse models of sickle cell anemia and thalassemia. Decreased eryptosis is observed in mice with deficient phosphoinositide-dependent kinase 1 (PDK1), platelet activating factor (PAF) receptor, transient receptor potential channel 6 (TRPC6), janus kinase 3 (JAK3), and taurine transporter (TAUT). Eryptosis may be a useful mechanism to remove defective erythrocytes prior to hemolysis. Excessive eryptosis may, however, compromise microcirculation and lead to anemia. © 2012 S. Karger GmbH, Freiburg.

Venkatramani R.,Childrens Hospital Los Angeles | Furman W.L.,St Jude Childrens Research Hospital | Fuchs J.,University of Tbingen | Warmann S.W.,University of Tbingen | Malogolowkin M.H.,Medical College of Wisconsin
Pediatric Drugs | Year: 2012

Hepatoblastoma is the most common primary malignant neoplasm of the liver in children. Improvements in chemotherapy and surgical techniques have increased survival rates for those with localized disease. The prognosis for patients with progressive or relapsed disease continues to be dismal. Complete resection by surgery or liver transplantation is necessary for cure. Few conventional chemotherapy agents have demonstrated activity in progressive or relapsed hepatoblastoma. Irinotecan has shown activity in relapsed and progressive hepatoblastoma. The efficacy of high-dose chemotherapy in this setting is unknown. Newer targeted agents that 'selectively' interfere with pathway targets involved in tumor growth and progression such as insulin-like growth factor, phosphatidylinositol 3-kinase (PI3K), Akt, and mammalian target of rapamycin (mTOR) are currently under development. Because of the rarity of hepatoblastoma, only a small minority of these agents will ever be evaluated in children with this disorder. Gene-directed therapy and immunotherapy have shown promising results in the preclinical setting, and should be investigated as future treatment options for advanced hepatoblastoma. © 2012 Springer International Publishing AG. All rights reserved.

Lyson T.R.,Yale University | Lyson T.R.,Marmarth Research Foundation | Joyce W.G.,University of Tbingen | Joyce W.G.,Yale University
Journal of Vertebrate Paleontology | Year: 2010

A fragmentary skull from the Hell Creek Formation (Maastrichtian) of southwestern North Dakota represents a new taxon of baenid turtle named herein Gamerabaena sonsalla. The length of the frontals, jugal contribution to the labial ridge, and convex contact between the vomer and the pterygoids indicate its affinities with the clade Palatobaena, but the new taxon clearly lacks the great posterior expansion of the triturating surface, complete absence of a lingual ridge, subrectangular skull, and wide angle between the maxillae that diagnose Palatobaena spp. A maximum parsimony analysis provides strong support for G. sonsalla as sister taxon to Palatobaena spp. Gamerabaena sonsalla has several morphological features that are intermediate between Plesiobaena antiqua and the morphologically disparate Palatobaena spp., including orbits that are oriented slightly dorsally and moderately expanded posterior triturating surfaces. Our phylogenetic analysis, combined with stratigraphic arguments, indicates that our skull-based taxon G. sonsalla could belong to the shell-based taxon "Baena" hayi. Similarly, the skull taxa Hayemys latifrons and Eubaena cephalica may be synonymous with the shell taxa Thescelus insiliens and "Baena" hatcheri, respectively. © 2010 by the Society of Vertebrate Paleontology.

Wohling T.,Lincoln Ventures Ltd. | Wohling T.,University of Tbingen | Vrugt J.A.,University of California at Irvine | Vrugt J.A.,University of Amsterdam | Vrugt J.A.,Los Alamos National Laboratory
Water Resources Research | Year: 2011

In the past two decades significant progress has been made toward the application of inverse modeling to estimate the water retention and hydraulic conductivity functions of the vadose zone at different spatial scales. Many of these contributions have focused on estimating only a few soil hydraulic parameters, without recourse to appropriately capturing and addressing spatial variability. The assumption of a homogeneous medium significantly simplifies the complexity of the resulting inverse problem, allowing the use of classical parameter estimation algorithms. Here we present an inverse modeling study with a high degree of vertical complexity that involves calibration of a 25 parameter Richards'-based HYDRUS-1D model using in situ measurements of volumetric water content and pressure head from multiple depths in a heterogeneous vadose zone in New Zealand. We first determine the trade-off in the fitting of both data types using the AMALGAM multiple objective evolutionary search algorithm. Then we adopt a Bayesian framework and derive posterior probability density functions of parameter and model predictive uncertainty using the recently developed differential evolution adaptive metropolis, DREAMZS adaptive Markov chain Monte Carlo scheme. We use four different formulations of the likelihood function each differing in their underlying assumption about the statistical properties of the error residual and data used for calibration. We show that AMALGAM and DREAMZS can solve for the 25 hydraulic parameters describing the water retention and hydraulic conductivity functions of the multilayer heterogeneous vadose zone. Our study clearly highlights that multiple data types are simultaneously required in the likelihood function to result in an accurate soil hydraulic characterization of the vadose zone of interest. Remaining error residuals are most likely caused by model deficiencies that are not encapsulated by the multilayer model and can not be accessed by the statistics and likelihood function used. The utilization of an explicit autoregressive error model of the remaining error residuals does not work well for the water content data with HYDRUS-1D prediction uncertainty bounds that become unrealistically large. Copyright © 2011 by the American Geophysical Union.

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