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Conicet, National University of Costa Rica and Plant Bioscience Ltd | Date: 2015-04-30

A polynucleotide having at least 80% sequence identity with the fill-length nucleotide sequence of SEQ ID NO: 1 and substantially identical polynucleotides; an isolated polypeptide having at least 80% sequence identity with the full-length amino acid sequence of SEQ ID NO: 2 and substantially identical polypeptides; and polynucleotides encoding the Ha WRKY76 polypeptide and substantially identical polypeptides are described. Also described are vectors and recombinant expression cassettes containing the c DNA polynucleotide, a polynucleotide encoding the Ha WRKY76 polypeptide, or substantially identical polynucleotides. Transgenic plants containing such expression cassettes, related methods and uses are also provided.

Piastrellini R.,CONICET | Arena A.P.,CONICET | Civit B.,CONICET
Energy | Year: 2017

The purpose of this paper is to carry out an updated energy Life-Cycle Assessment of soybean biodiesel produced in the Pampean region of Argentina and to analyze the influence of different tillage systems on the Energy Return on Investment (EROI). It aims to identify the processes, materials and methodological aspects that significantly affect biofuel EROI. The procedure considers the main processes and operations of both the agriculture and industrial stages of biofuel production system, but the main novelty of this study is linking EROI with farming and conservation practices and not in the chemical processing of the oil. The results obtained represent the current average energetic performance of soy-based biodiesel produced in the considered region. The EROI values are very encouraging, demonstrating that this biodiesel provides a net energy gain. The results also show that conservation agriculture and the implementation of practices that improve crop yield do not always determine better energetic performance. Sensitivity analysis confirms that EROI values of soybean biodiesel are more responsive to methodological choices such as the system's boundary definition and the choice of the allocation method rather than to the physical aspects of the productive system such as tillage and water management practices. © 2017 Elsevier Ltd

Sublethal effects of the pesticide chlorpyrifos were evaluated in the crab Zilchiopsis collastinensis (Decapoda, Trichodactylidae). Crabs were exposed to high concentrations of chlorpyrifos at the beginning of the experiment and controlled dilution, under natural light and temperature conditions. A control and three concentrations (22.4, 41.25 and 61.4 µg chlorpyrifos L−1) were evaluated in triplicate. Nine crabs per concentration and day were used. The gills, hepatopancreas and ovaries were sampled before pesticide exposure (day 0) and 8, 15 and 22 days later, when concentrations were diluted and below the detection limits. The histopathological effects and their variations in time were observed and quantified. In gills, hyperplasias were observed in several cases, mainly in crabs exposed to chlorpyrifos. The number of collapsed lamellae and the number of affected lamellae quickly increased in exposed crabs, as effects were observed on day 8 and remained until day 22. In hepatopancreas there was an increase in the number of F and B -cells and affected tubules, especially after 22 days of exposure (p<0.05). In ovaries, there were no effects on gonadosomatic indexes or oocyte volume, but there was a significant increase in the atretic oocyte proportion related to pesticide exposure (p<0.05). The histopathological effects on the gills, hepatopancreas and ovaries were observed after exposure and persist even after dilution, and might be related to earlier exposures. Thus, these histopathological effects might be used as pesticide biomarkers even after the pesticide is not detected by chemical methods. © 2017 Elsevier Inc.

Juanico L.E.,Bariloche Atomic Center | Di Lalla N.,Bariloche Atomic Center | Gonzalez A.D.,CONICET
Renewable and Sustainable Energy Reviews | Year: 2017

A comprehensive analysis of low-cost solar collectors based on a single long plastic LDPE hose resting on a roof and working by thermosiphon is performed. This lay-out involves two challenging issues, high hydraulic resistances and low tilt angles, which shall be solved. We have developed a full thermal-hydraulic and thermal-solar modeling to optimize the collector's parameters to achieve a good performance under thermosiphon conditions. This modeling leads to strong coupling effects between the variables, showing that thermal-hydraulic mechanisms are as important as thermal-solar phenomena. We have investigated several cases comprising variation in the collector's parameters: hose diameter and length, tank height and volume, number and quality of glazing layers, roof tilt angle and climatic conditions. It is found that, all year round, this collector can provide 150 l of sanitary hot water at minimum 45 °C in tropical and temperate climates by using a 100-meter 1.5″-diameter LDPE hose, for roofs tilted 20° or more. In addition, for horizontal roofs, the desired goal could be achieved with a 2″-diameter hose instead. On the other hand, the model also shows that using longer hoses and many wrapping layers lead to worse performances, meanwhile to raise the tank causes slight improvements. The proposed modeling, comprising three coupled phenomena, makes possible to design a simple and robust collector that can be locally manufactured using materials available in hardware store. Due to cost and maintenance feasibility, we find that this option could be useful for developing countries with temperate and tropical climates. © 2017 Elsevier Ltd

Sandoval M.L.,CONICET | Camerucci M.A.,CONICET
Ceramics International | Year: 2017

In this work, the thermogelling behavior of aqueous mullite-bovine serum albumin (BSA) suspensions was studied by dynamic rheology in order to determine the experimental conditions that must be used to form mullite green bodies by thermal consolidation. Viscoelastic properties (G′ and G′′) as a function of temperature (30–95 °C) and time were determined by temperature sweep tests and time sweep tests, respectively. On the other hand, the influence of methylcellulose (MC) (2 wt%) as a binder on the viscoelastic properties of the aqueous mullite-protein system as a function of both experimental parameters (temperature and time) was also studied. In addition, shear flow properties of aqueous mullite (40 vol%; 0.45 wt% of polyacrylic polyelectrolyte as a dispersant)–BSA (10 and 15 vol%)-MC (2 wt%) suspensions were analyzed to obtain information on the rheological behavior of the suspensions at room temperature. The results obtained showed that the presence of mullite particles and MC changed the onset temperature of gelation of the protein and increased the gelation time. Thus, both the mullite particles and methylcellulose intervened in the formation of the developed protein gel. © 2017 Elsevier Ltd and Techna Group S.r.l.

This article analyzes the existing tensions between the recognition of human rights - especially the right to adequate food as it is defined in international agreements and treaties - and the insufficient connection made with care, understood as the set of activities necessary to satisfy the basic needs of existence and human and social reproduction. Applying a methodological approach based in rights and gender, the article analyzes, on one hand, the scope of the right to food and its impact at the level of public institutionality, and on the other, the recent recognition of care as a right at a regional level and its persistent invisibilization in public policies. The results obtained allow for a research and action agenda that identifies tensions and opportunities to achieve universalization in the exercise of rights based in comprehensive and interdependent public policies.

Torres Carbonell P.J.,CONICET | Rodriguez Arias L.,YPF S.A. | Atencio M.R.,YPF S.A.
Tectonics | Year: 2017

Published balanced structural interpretations of the Fuegian thrust-fold belt (southernmost Andes) fail to address aspects such as basement shortening in the thrust-fold belt or its structural connection with the central belt of the orogen. We tackle this deficiency by constructing four serial balanced cross sections based on surface geologic information, 2-D reflection seismic lines, and well logs, which depict the first-order structural geometry and kinematics from the thrust front to the internal thrust-fold belt. The interpretation reveals three main tectonostratigraphic packages separated by major detachments: basement (Paleozoic-Upper Jurassic), Cretaceous, and Paleogene, all variably involved in thrusting along strike. Minimum shortening in the Paleogene cover ranges between 16% and 43%, and significant style changes are observed across and along the thrust wedge. We show that basement thrust sheets have a major role in the construction of the thrust-fold belt; some of them were emplaced below the thrust front during late Oligocene or early Miocene times. The kinematic evolution of the thrust-fold belt indicates that the active detachments depended on the existence of high pore pressure to propagate forward. Our model shows that this pore pressure buildup was controlled by overburden, mean rock impermeability, and strain rate; the variable interaction among these factors controlled the propagation and style of the thrust wedge. ©2016. American Geophysical Union. All Rights Reserved.

Ballare C.L.,CONICET | Pierik R.,University Utrecht
Plant Cell and Environment | Year: 2017

Plants use photoreceptor proteins to detect the proximity of other plants and to activate adaptive responses. Of these photoreceptors, phytochrome B (phyB), which is sensitive to changes in the red (R) to far-red (FR) ratio of sunlight, is the one that has been studied in greatest detail. The molecular connections between the proximity signal (low R:FR) and a model physiological response (increased elongation growth) have now been mapped in considerable detail in Arabidopsis seedlings. We briefly review our current understanding of these connections and discuss recent progress in establishing the roles of other photoreceptors in regulating growth-related pathways in response to competition cues. We also consider processes other than elongation that are controlled by photoreceptors and contribute to plant fitness under variable light conditions, including photoresponses that optimize the utilization of soil resources. In examining recent advances in the field, we highlight emerging roles of phyB as a major modulator of hormones related to plant immunity, in particular salicylic acid and jasmonic acid (JA). Recent attempts to manipulate connections between light signals and defence in Arabidopsis suggest that it might be possible to improve crop health at high planting densities by targeting links between phyB and JA signalling. © 2017 John Wiley & Sons Ltd.

Olivera J.,CONICET | Challu L.,University of Belgrano | Penedo J.M.G.,CONICET | Roussos A.,CONICET
Psychotherapy | Year: 2017

There is no consensus among different therapeutic approaches on the process of termination when therapy does not have a prefixed duration. Moreover, both clinicians and researchers are still exploring decision making in the termination of treatment. The present study assessed former client's perspective of therapy termination in a nonprobabilistic sample from Buenos Aires, Argentina. Seventy-three semistructured interviews, lasting60 min each, were conducted with participants that had finished a therapeutic treatment or dropped out. They were asked about several aspects of therapy, including their experience of termination, specifically who decided to terminate, if there was agreement on termination or not, and their thoughts on the termination process. All interviews were transcribed and analyzed using an adaptation of Consensual Qualitative Research (CQR). Quantitative analyses were also conducted to examine associations between variables. Two main factors emerged from the analysis: client/therapist initiative on termination; and level of agreement between client and therapist regarding termination. Whereas nearly all (95%) of therapistinitiated termination cases agreed on termination, client-initiated termination cases could be sorted in agreed (49%) and disagreed (51%) terminations. Both therapist-initiated terminations and agreed upon terminations presented more categories of positive termination motives, better therapeutic bond, and higher overall satisfaction with treatment. Implications for research and clinical practice are discussed. © 2017 American Psychological Association.

We present a field-based work which illustrates the fracture patterns of the carbonate-silicoclastic Yacoraite Formation in the Tin Tin anticline, a basement fault-related fold located in southern part of the Eastern Cordillera, northwestern Argentina. The fracture patterns include small-scale strike-slip faults (vertical shear fractures and en echelon arrays), thrust faults, extension fractures (joints, veins and normal faults) and stylolites. Extensional mesostructures were formed by along-foreland stretching, prior to the contractional ones that were formed by the layer-parallel shortening mechanism. Furthermore, all fractures are interpreted to be formed before or at the early stages of folding and thrusting during the Andean contraction, all of them belonging to the Eocene thrust belt-foreland system at the Calchaquí Valley of northwestern Argentina. © 2017 Elsevier Ltd

Morphometrics can be an important tool in systematic studies, providing taxonomists with strong elements of quantification and formal hypothesis testing. Here, these tools are tested for the trilobite Leptoplastides marianus (Hoek) which was originally described on the basis of three deformed specimens from west Tarija, Bolivia. Following the conclusions of Harrington & Leanza, a wide range of morphological variation is accepted for this species, and the name was applied to a large number of specimens from north-western Argentina. Based on specimens collected from the quebrada Moya (Huacalera, Jujuy), as well as on material in the Harrington & Leanza collections in the University of Buenos Aires, traditional morphometric and geometric morphometric methods were used to evaluate the variation of the cranidial shape of L. marianus sensu Harrington & Leanza. The results allow discrimination between two clearly different morphotypes. The name L. marianus should be restricted to the type specimens, given the deformation of these materials. In addition, L. argentinensis and L. granulosus are both valid names for the two morphotypes recognized in the present paper. © The Trustees of the Natural History Museum, London 2017. All rights reserved.

Fernandez A.,CONICET
Trends in Biotechnology | Year: 2017

Immune checkpoint blockades induced by antibodies are revolutionizing cancer therapy. Combinations of checkpoint immunotherapies with kinase inhibitors (KIs) are being clinically evaluated as oncogenic mutations arise. Off-target KI cross-reactivity will often compromise synergistic efficacy, with KIs suppressing T-cell functionalities that checkpoint blockers are purportedly boosting. This incompatibility may be removed through molecular optimization. © 2017 Elsevier Ltd.

Tagliazucchi E.,Goethe University Frankfurt | Chialvo D.R.,CONICET
AIP Conference Proceedings | Year: 2013

In this essay we elaborate on recent evidence demonstrating the presence of a second order phase transition in human brain dynamics and discuss its consequences for theoretical approaches to brain function. We review early evidence of criticality in brain dynamics at different spatial and temporal scales, and we stress how it was necessary to unify concepts and analysis techniques across scales to introduce the adequate order and control parameters which define the transition. A discussion on the relation between structural vs. dynamical complexity exposes future steps to understand the dynamics of the connectome (structure) from which emerges the cognitome (function). © 2013 American Institute of Physics.

Twenty-seven Gomphrena names are here investigated, and discussed. Seventeen names are typified (sixteen lectotypes, one neotype) in the present paper on specimens preserved at B, GOET, M, P, and S, while isolectotypes are found at B, BM, BR, CORD, F, G, M, P, S, and US. Concerning the other ten names, they were previously dicusssed by Holzhammer, who reported the word “Typus”. According to the Art. 7.10 of the ICN Holzhammer’s statements are here interpreted as lectotypifications. © 2017 Magnolia Press.

Piatti A.E.,National University of Cordoba | Piatti A.E.,CONICET
Monthly Notices of the Royal Astronomical Society | Year: 2017

We turn our attention to Haffner 9, aMilkyWay open cluster whose previous fundamental parameter estimates are far from being in agreement. In order to provide with accurate estimates, we present high-quality Washington CT1 and Johnson BVI photometry of the cluster field.We put particular care in statistically cleaning the colour-magnitude diagrams (CMDs) from field star contamination, which was found a common source in previous works for the discordant fundamental parameter estimates. The resulting cluster CMD fiducial features were confirmed from a proper motion membership analysis. Haffner 9 is a moderately young object (age ~350 Myr), placed in the Perseus arm - at a heliocentric distance of ~3.2 kpc -, with a lower limit for its present mass of ~160 M ⊙ and of nearly metal solar content. The combination of the cluster structural and fundamental parameters suggest that it is in an advanced stage of internal dynamical evolution, possibly in the phase typical of those with mass segregation in their core regions. However, the cluster still keeps its mass function close to that of the Salpeter's law. © 2016 The Authors.

In-vial filtration with dispersive solid-phase extraction (d-SPE) clean-up of QuEChERS (quick, easy, cheap, effective, rugged and safe) extracts is proposed for the determination of ethylphenols (EPs) in red wines. Analytes were extracted from 5 mL wine sample (previously alkalinized with 0.5% sodium hydroxide) using 5 mL acetonitrile. For phase separation, 1.5 g NaCl and 4 g anhydrous MgSO4 were added. Then, a 0.5 mL aliquot of the partitioned supernatant was cleaned-up using d-SPE and in-vial filtration with a combination of anhydrous CaCl2 (100 mg) and primary-secondary amine (PSA, 25 mg) as sorbents. The proposed method provided limits of quantification (LOQs) ranging from 0.024 to 0.04 mg L−1. Considering matrix-matched calibration as quantification technique, the recoveries (accuracy) ranged between 73% and 116%. The method was applied for the determination of EPs in 15 commercial wines of Argentina, where 4-EP was quantified at concentrations ranging from 0.25 to 3.01 mg L−1. © 2017 Elsevier Ltd

De Rossi M.E.,CONICET | Bromm V.,University of Texas at Austin
Monthly Notices of the Royal Astronomical Society | Year: 2017

We study the contribution of the first galaxies to the far-infrared/sub-millimeter (FIR/sub-mm) extragalactic background light (EBL) by implementing an analytical model for dust emission. We explore different dust models, assuming different grain-size distributions and chemical compositions. According to our findings, observed reradiated emission from dust in dwarfsize galaxies at z ~ 10 would peak at a wavelength of ~500 μm with observed fluxes of ~10-3-10-2 nJy, which is below the capabilities of current observatories. In order to be detectable, model sources at these high redshifts should exhibit luminosities of ≳1012 L⊙, comparable to that of local ultraluminous systems. The FIR/sub-mm-EBL generated by primeval galaxies peaks at ~500 μm, with an intensity ranging from ~10-4 to 10-3 nWm-2 sr-1, depending on dust properties. These values are ~3-4 orders of magnitude below the absolute measured cosmic background level, suggesting that the first galaxies would not contribute significantly to the observed FIR/sub-mm-EBL. Our model EBL exhibits a strong correlation with the dust-to-metal ratio, where we assume a fiducial value of D = 0.005, increasing almost proportionally to it. Thus, measurements of the FIR/sub-mm-EBL could provide constraints on the amount of dust in the early Universe. Even if the absolute signal from primeval dust emission may be undetectable, it might still be possible to obtain information about it by exploring angular fluctuations at ~500 μm, close to the peak of dust emission from the first galaxies. © 2016 The Authors.

Tonini M.H.,CONICET | Palma E.D.,CONICET
Estuarine, Coastal and Shelf Science | Year: 2017

Semidiurnal (M2, S2, N2 and K2), diurnal (K1,O1 and P1) and quarter-diurnal (M4, MN4 and MS4) barotropic tides over the North Patagonian Gulfs of Argentina: San Matías, (SMG), Nuevo (NG) and San José (SJG) are examined using a regional numerical model. Detailed comparison of computed elevations and currents with those obtained from harmonic analysis of few long-term observational records showed good agreement. A large amplification of all semidiurnal waves is recorded when they cross SMG mouth. Most of the tidal energy coming from the south at this frequency dissipates to the northeast of Valdés Península, where the largest tidal currents are located. While M2 currents (up to 2–2.5 m/s) are dominant, there are large S2 and N2 currents and locally intensified diurnal currents (5–10 cm/s) in some outer shelf locations. At difference with the semidiurnal and diurnal tides the higher harmonics M4, MS4 and MN4 develop a large amplification inside the NG. The model revealed a complex field of tidal residual currents. The intensity of such currents in some locations are of the same order of magnitude as those generated by winds or offshore forcing. We have identified three main patterns of residual circulation: regional coastal currents and gulf-wide gyres; inlet eddies and, topographic eddies. Vorticity balances and sensitivity experiments indicate that non-linear advection and bottom topography are the key mechanisms involved in the generation of these residual structures. © 2017 Elsevier Ltd

Brunini A.,CONICET
Monthly Notices of the Royal Astronomical Society | Year: 2017

In this paper, we show that the decoupling of binary pairs by tidal interaction and Kozai oscillations acting together can generate single objects in a slow-rotation-rate state. This mechanism has the merit of not being strongly dependent on the size or shape of the objects. The key parameter leading the process is ω/n, the ratio between the rotation rate and the orbital mean motion of the binary, which must be > 1. The proposed mechanism could also operate in other populations of minor bodies. © 2016 The Authors.

Megevand A.,CONICET | Ramirez S.,CONICET
Nuclear Physics B | Year: 2017

Strongly first-order phase transitions, i.e., those with a large order parameter, are characterized by a considerable supercooling and high velocities of phase transition fronts. A very strong phase transition may have important cosmological consequences due to the departures from equilibrium caused in the plasma. In general, there is a limit to the strength, since the metastability of the old phase may prevent the transition to complete. Near this limit, the bubble nucleation rate achieves a maximum and thus departs from the widely assumed behavior in which it grows exponentially with time. We study the dynamics of this kind of phase transitions. We show that in some cases a gaussian approximation for the nucleation rate is more suitable, and in such a case we solve analytically the evolution of the phase transition. We compare the gaussian and exponential approximations with realistic cases and we determine their ranges of validity. We also discuss the implications for cosmic remnants such as gravitational waves. © 2017 The Author(s)

Alcain P.N.,CONICET | Dorso C.O.,CONICET
Nuclear Physics A | Year: 2017

The study of neutron rich matter, present in neutron star, proto-neutron stars and core-collapse supernovae, can lead to further understanding of the behavior of nuclear matter in highly asymmetric nuclei. Heterogeneous structures are expected to exist in these systems, often referred to as nuclear pasta. We have carried out a systematic study of neutrino opacity for different thermodynamic conditions in order to assess the impact that the structure has on it. We studied the dynamics of the neutrino opacity of the heterogeneous matter at different thermodynamic conditions with semiclassical molecular dynamics model already used to study nuclear multifragmentation. For different densities, proton fractions and temperature, we calculate the very long range opacity and the cluster distribution. The neutrino opacity is of crucial importance for the evolution of the core-collapse supernovae and the neutrino scattering. © 2017 Elsevier B.V.

Fernandez F.M.,CONICET
Annals of Physics | Year: 2017

We study the connection between the solutions of the Schrödinger equation with an inverse square-root potential in three and one dimension. In particular we show that an approximate analytical expression for the eigenvalues of the one-dimensional model also applies to the three-dimensional one for zero angular-momentum quantum number. © 2017 Elsevier Inc.

Meier L.A.,CONICET | Castellani N.J.,CONICET
Computational Materials Science | Year: 2017

In the present work, the adsorption of Sn atoms on the Au(1 1 1) surface was theoretically studied in the framework of density functional theory with a slab model. The results show that the most likely site for the adsorption of Sn is the FCC hollow site at low Sn coverage while at full monolayer degeneracy is produced for the four possible adsorption sites. The energy barrier for Sn surface diffusion is of near 0.1 eV at low coverage and negligible at high coverage. The magnitude of the Sn adsorption energy, Eads, decreases as the overlayer grows. For high coverage values the Sn-Sn interaction has a predominant contribution to Eads. It was observed that for 1/2 ML coverage the adsorbed Sn atoms and the Au atoms of the first and second layers of the substrate can suffer a reordering, resulting in an important surface reconstruction, giving a surface alloy superstructure. An electronic transfer from tin to gold takes place, which is significant at low Sn coverage. The binding of Sn to Au was analyzed in terms of the electronic structure of the Sn/Au(1 1 1) system at different values of coverage. © 2016 Elsevier B.V.

Osteoporosis and obesity are chronic disorders that are increasing in prevalence. The pathophysiology of these diseases is multifactorial and it includes genetic, environmental and hormonal determinants. Basic and clinical studies support an important interaction between adipose tissue and the skeleton similar to that found in osteoporosis and obesity. The belief that obesity is protective for bone has recently been revised. In fact, excess of fat mass might be a risk factor for osteoporosis and fragility fractures. Increasing evidence seems to indicate that different factors released by thefat tissue could play a key role in skeletal health. Adipokines, cytokines and free-fatty acids secreted by the obese fat mass can regulate bone remodelling decreasing bone formation and increasing bone resorption. Moreover they increase oxidative stress, increasing even more the negative effect on bone mass. This review considers literature data to understand bone-fat interactions and the clinical implications of linking obesity to osteoporosis.

Vazquez M.S.,CONICET | Cesari S.N.,CONICET
Journal of South American Earth Sciences | Year: 2017

A palynological study of the Yacimiento Los Reyunos Formation (San Rafael Block) Argentina was carried out in order to correlate the palynological data with other Permian assemblages and biozones from South America. The unit is included in the Cochicó Group deposited under the volcanic influence of the Choiyoi event. The palynological assemblages recovered from subsurface samples show a dominance of taeniate bisaccates like Corisaccites, Lueckisporites, Lunatisporites, Protohaploxypinus, Vittatina and Weylandites. A Lueckisporites complex, which would have biostratigraphical value, is established to include species of Lueckisporites, Corisaccites and Staurosaccites showing a wide morphological variation. The composition of the assemblages allows their inclusion in the Lueckisporites/Weylandites Biozone of Argentina, which is closely related to other biozones from southern South America. Analysis of the distribution of the species using cluster analysis confirms its similarity with the biozones from Bolivia and Brazil. Radiometric datings suggest an age not older than Kungurian for the occurrence of these assemblages in the Southern Hemisphere. © 2017 Elsevier Ltd

The Neuquén Basin in northwestern Patagonia, Argentina, holds the most important record of Cretaceous dinosaurs in South America.The Neuquén Group (Upper Cretaceous) is the richest dinosaur-bearing unit of the basin. It comprises the Río Limay, the Río Neuquén and the Río Colorado subgroups. In this study, dinosaur remains from the Río Neuquén and the Río Colorado subgroups outcropping in Mendoza are examined. In this group, isolated, disarticulated or partially articulated sauropods and theropods are abundant. However, little is known about the diagenetic history of fossil assemblages. In southern Mendoza, three fossiliferous sites were found in the areas of Paso de las Bardas (Quebrada Norte) and Cerro Guillermo (CG1, CG2). This study aims to add to the knowledge of diagenetic processes involving dinosaur remains from the Neuquén Group, as well as their relation to the depositional environment. Histologic features and diagenetic processes of dinosaur bones were analyzed through thin sections in order to interpret the degree of taphonomic alteration. The fossil-diagenetic processes inferred include substitution, fracturing, plastic deformation and different permineralization events. Combined analyses through X-ray diffractometry (XRD) and petrographic studies reveal the substitution of hydroxyapatite by francolite. The presence of fluorine -in one of the cases- suggests a link between the elemental composition and depositional environments: floodplain and fluvial channel. Permineralization stages include infilling of vascular canals, trabeculae and fractures with iron oxides and iron carbonate minerals during the burial history. This contribution represents an integral approach to the study of Cretaceous dinosaurs for assessing the diagenetic changes in the bone microstructure and the differential preservation of fossil remains in fluvial environments. © 2017, Servicio Nacional de Geologia y Mineria. All Rights Reserved.

International Journal of Climatology | Year: 2017

The purpose of this study is to assess the ability of Coupled Model Intercomparison Project 5 (CMIP5) models in reproducing the variability and change of the austral summer precipitation observed in Southeastern South America (SESA) along the 20th century and beginning of the 21st. Models show a reduction in mean precipitation biases and inter-model dispersion, and a significant improvement in the representation of the leading pattern of precipitation interannual variability (EOF1), in comparison with Coupled Model Intercomparison Project 3 (CMIP3) models. Changes of the EOF1 activity in the present climate, as represented by both, climate model simulations and rainfall gridded datasets, evidence an increase of the frequency of EOF1 positive events (associated with positive precipitation anomalies in SESA and negative ones in the South Atlantic Convergence Zone) and a decrease of the frequency of EOF1 negative events. Nevertheless there are still large uncertainties due to model differences and the internal variability of the climate system. In order to reduce the impact of model uncertainties, an ensemble of the climate simulations that represent better the features associated with EOF1 activity was built, regardless to which model they correspond. The results obtained with this ensemble confirm that largest precipitation trends in SESA are those represented by climate simulations associated with an increase (decrease) of EOF1 positives (negative) events. It was also found that positive precipitation trends in SESA resulted from climate simulations forced by anthropogenic sources are the largest and significantly different from those from simulations forced by natural sources only, which are not significantly different from zero. © 2017 Royal Meteorological Society.

Garibotti I.A.,CONICET | Villalba R.,CONICET
Polar Biology | Year: 2017

Understanding the process of primary succession is a relevant topic in restoration and global change ecology, and provides the basis for classic dating methods in geomorphology, such as lichenometry and dendrochronology. The aim of this study is to investigate the colonization by lichens and vascular plants of two pro-glacial chronosequences encompassing the late- and mid-Holocene periods in the sub-Antarctic sub-region of South America. We use this information to address questions related to the pattern of Magellanic forests recovery after disturbance and the applicability of lichenometry for developing glacier retreat chronologies. Progression of succession to a state with high vascular plant cover was slow, and some moraines remained unforested for about 2000 years. Our results contrast with previous reports indicating a quick development of mature forest states on disturbed terrains, suggesting large regional variability on the course of succession. Environmental conditions seem propitious for lichens that colonize immediately after moraine formation. Lichens grow at relatively high rates in comparison to other world areas, but half as fast as in Antarctica and sub-Antarctic islands. Growth rates for the Rhizocarpon Ram. em. Th. Fr. sub-gen. Rhizocarpon group increase with lichen sizes up to ca. 50 mm and decrease in larger thalli, leading to a sigmoidal lichenometric growth curve that extends the applicable range of lichenometry to the last 5700 years in dry sites in the Magellanic province of the sub-Antarctic sub-region. Our results suggest that lichenometry is an effective technique in multi-proxy approaches for reconstructing glacier fluctuations, and agree with early studies in Antarctica suggesting that lichen annual growth rate is a sensitive attribute for the biomonitoring of climate changes. © 2017 Springer-Verlag Berlin Heidelberg

Vennari V.V.,CONICET | Pujana I.,University of Texas at Dallas
Journal of South American Earth Sciences | Year: 2017

An association of ammonoids and radiolarians retrieved from a sedimentary section of the Vaca Muerta Formation at Vega de Escalone, Neuquén Basin, Argentina, was analized under a strict stratigraphic control. Nine ammonoid assemblage biozones were identified, indicating an age span from Early Tithonian to Late Berriasian/earlymost Valanginian for the Vaca Muerta Formation at the studied section. In connection to the ammonoid record, two radiolarian faunas were identified and named J3A1 and J3B1. Fauna J3A1, corresponding to the Virgatosphinctes andesensis Biozone, is dominated by nasellarian genera and represents the first Lower Tithonian radiolarian fauna described from the Neuquén Basin. Fauna J3B1, linked to the interval assigned to the Substeueroceras koeneni Biozone (Late Tithonian–Early Berriasian), yields abundant representatives of the Pantanellid Family. The presence of Complexapora kozuri (Kiessling and Zeiss) and Loopus primitivus (Matsuoka and Yao), two important radiolarian primary markers of the Late Jurassic in North America, supports a Late Tithonian age for at least part of the S. koeneni Biozone in the studied area. Nor certain Berriasian radiolarian faunas nor elements of the Vallupinae Family were identified so far at the Vega de Escalone section. © 2017 Elsevier Ltd

Rios-Tamayo D.,CONICET
Revista del Museo Argentino de Ciencias Naturales, Nueva Serie | Year: 2016

A new species of the spider genus Actinopus Perty from Cochabamba, Bolivia is described under the name of Actinopus cochabamba sp. n. This is the second species of the genus described for the country. Detailed morphological description and illustrations of the new species are presented.

News Article | April 17, 2017
Site: cerncourier.com

Fluorescence is rare in land animals, being largely limited to parrots and marine turtles. Now, for the first time, it has been found in a frog. Carlos Taboada of CONICET in Buenos Aires and colleagues studied South American polka-dot tree frogs (Hypsiboas punctuatus) collected near Santa Fe in Argentina. The colours of these frogs are normally a combination of muted greens, yellows and reds, but in dim light and UV illumination they glow bright blue and green. This is genuine fluorescence, not the more common bioluminescence in which organisms make their own light. The fluorescent molecules are unlike those in any other animals, being derived from dihydroisoquinoline. In twilight or night-time conditions, the fluorescence contributes 18–29% of the total emerging light, enhancing a creature’s visibility, particularly for amphibians, but the reasons for the fluorescence are still not known.

Wilson R.P.,University of Swansea | Quintana F.,CONICET | Quintana F.,Wildlife Conservation Society | Hobson V.J.,University of Swansea
Proceedings of the Royal Society B: Biological Sciences | Year: 2012

Variation in the physical characteristics of the environment should impact the movement energetics of animals. Although cognizance of this may help interpret movement ecology, determination of the landscape-dependent energy expenditure of wild animals is problematic. We used accelerometers in animal-attached tags to derive energy expenditure in 54 free-living imperial cormorants Phalacrocorax atriceps and construct an energy landscape of the area around a breeding colony. Examination of the space use of a further 74 birds over 4 years showed that foraging areas selected varied considerably in distance from the colony and water depth, but were characterized by minimal power requirements compared with other areas in the available landscape. This accords with classic optimal foraging concepts, which state that animals should maximize net energy gain by minimizing costs where possible and show how deriving energy landscapes can help understand how and why animals distribute themselves in space. © 2011 The Royal Society.

Victoria Martin M.,CONICET | Fernando Fiol D.,CONICET | Sundaresan V.,University of California at Davis | Julian Zabaleta E.,CONICET | Pagnussat G.C.,CONICET
Plant Cell | Year: 2013

Reactive oxygen species (ROS) can function as signaling molecules, regulating key aspects of plant development, or as toxic compounds leading to oxidative damage. In this article, we show that the regulation of ROS production during megagametogenesis is largely dependent on MSD1, a mitochondrial Mn-superoxide dismutase. Wild-type mature embryo sacs show ROS exclusively in the central cell, which appears to be the main source of ROS before pollination. Accordingly, MSD1 shows a complementary expression pattern. MSD1 expression is elevated in the egg apparatus at maturity but is downregulated in the central cell. The oiwa mutants are characterized by high levels of ROS detectable in both the central cell and the micropylar cells. Remarkably, egg apparatus cells in oiwa show central cell features, indicating that high levels of ROS result in the expression of central cell characteristic genes. Notably, ROS are detected in synergid cells after pollination. This ROS burst depends on stigma pollination but precedes fertilization, suggesting that embryo sacs sense the imminent arrival of pollen tubes and respond by generating an oxidative environment. Altogether, we show that ROS play a crucial role during female gametogenesis and fertilization. MSD1 activity seems critical for maintaining ROS localization and important for embryo sac patterning. © 2013 American Society of Plant Biologists. All rights reserved.

Garcia-Mata I.,CONICET | Vallejos R.O.,Brazilian Center for Research in Physics (CBPF) | Wisniacki D.A.,University of Buenos Aires
New Journal of Physics | Year: 2011

The fidelity amplitude (FA) is a quantity of paramount importance in echo-type experiments. We use semiclassical theory to study the average FA for quantum chaotic systems under external perturbation. We explain analytically two extreme cases: the random dynamics limit-attained approximately by strongly chaotic systems-and the random perturbation limit, which shows a Lyapunov decay. Numerical simulations help us to bridge the gap between both the extreme cases. © IOP Publishing Ltd and Deutsche Physikalische Gesellschaft.

Mougabure-Cueto G.,CONICET | Picollo M.I.,CONICET
Acta Tropica | Year: 2015

Chagas disease is a chronic parasitic infection restricted to America. The disease is caused by the protozoa Trypanosoma cruzi, which is transmitted to human through the feces of infected triatomine insects. Because no treatment is available for the chronic forms of the disease, vector chemical control represents the best way to reduce the incidence of the disease. Chemical control has been based principally on spraying dwellings with insecticide formulations and led to the reduction of triatomine distribution and consequent interruption of disease transmission in several areas from endemic region. However, in the last decade it has been repeatedly reported the presence triatomnes, mainly Triatoma infestans, after spraying with pyrethroid insecticides, which was associated to evolution to insecticide resistance. In this paper the evolution of insecticide resistance in triatomines is reviewed. The insecticide resistance was detected in 1970s in Rhodnius prolixus and 1990s in R. prolixus and T. infestans, but not until the 2000s resistance to pyrthroids in T. infestans associated to control failures was described in Argentina and Bolivia. The main resistance mechanisms (i.e. enhanced metabolism, altered site of action and reduced penetration) were described in the T. infestans resistant to pyrethrods. Different resistant profiles were demonstrated suggesting independent origin of the different resistant foci of Argentina and Bolivia. The deltamethrin resistance in T. infestans was showed to be controlled by semi-dominant, autosomally inherited factors. Reproductive and developmental costs were also demonstrated for the resistant T. infestans. A discussion about resistance and tolerance concepts and the persistence of T. infestans in Gran Chaco region are presented. In addition, theoretical concepts related to toxicological, evolutionary and ecological aspects of insecticide resistance are discussed in order to understand the particular scenario of pyrethroid resistance in triatomines. © 2015 Elsevier B.V..

Schueftan A.,Austral University of Chile | Gonzalez A.D.,CONICET
Energy Policy | Year: 2015

Major cities in South-central Chile suffer high levels of particulate matter PM10 and PM2.5 due to combustion of solid fuels for heating. Exposure to these air pollutants is recognized as a major contribution to ill health in the region. Here we discuss new strategies to reduce air pollution. Regulations and subsidies focusing on improved combustion by providing drier wood fuel and better stoves have been in effect since 2007. However, air pollution due to combustion of wood fuel has been steadily rising, along with reports on health consequences. The paper analyzes a survey of 2025 households in the city of Valdivia, which found that wood fuel quality, stove renewal, and awareness of programs are strongly affected by income level, and that higher consumption of wood fuel is found in households already having better stoves and drier wood fuel. The analysis suggests that regulations intended to improve combustion are influenced by user's behavior and have limited potential for lowering pollution. We conclude that thermal refurbishment has a larger potential for improvement, not yet been implemented as an energy policy for the majority. Here we propose improvements and additions to current programs to enhance effectiveness and cover the whole social spectrum. © 2015 Elsevier Ltd.

Kazantzidis S.,Ohio State University | Abadi M.G.,CONICET | Navarro J.F.,University of Victoria
Astrophysical Journal Letters | Year: 2010

Cosmological simulations indicate that cold dark matter (CDM) halos should be triaxial. Validating this theoretical prediction is, however, less than straightforward because the assembly of galaxies is expected to modify halo shapes and to render them more axisymmetric.We use a suite of N-body simulations to quantitatively investigate the effect of the growth of a central disk galaxy on the shape of triaxial dark matter halos. In most circumstances, the halo responds to the presence of the disk by becoming more spherical. The net effect depends weakly on the timescale of the disk assembly but noticeably on the orientation of the disk relative to the halo principal axes, and it is maximal when the disk symmetry axis is aligned with the major axis of the halo. The effect depends most sensitively on the overall gravitational importance of the disk. Our results indicate that exponential disks whose contribution peaks at less than ∼50% of their circular velocity are unable to noticeably modify the shape of the gravitational potential of their surrounding halos. Many dwarf and low surface brightness galaxies are expected to be in this regime, and therefore their detailed kinematics could be used to probe halo triaxiality, one of the basic predictions of the CDM paradigm. We argue that the complex disk kinematics of the dwarf galaxy NGC 2976 might be the reflection of a triaxial halo. Such signatures of halo triaxiality should be common in galaxies where the luminous component is subdominant. © 2010 The American Astronomical Society. All rights reserved.

Lipina S.J.,CONICET | Posner M.I.,University of Oregon
Frontiers in Human Neuroscience | Year: 2012

Although the study of brain development in non-human animals is an old one, recent imaging methods have allowed non-invasive studies of the gray and white matter of the human brain over the lifespan. Classic animal studies show clearly that impoverished environments reduce cortical gray matter in relation to complex environments and cognitive and imaging studies in humans suggest which networks may be most influenced by poverty. Studies have been clear in showing the plasticity of many brain systems, but whether sensitivity to learning differs over the lifespan and for which networks is still unclear. A major task for current research is a successful integration of these methods to understand how development and learning shape the neural networks underlying achievements in literacy, numeracy, and attention. This paper seeks to foster further integration by reviewing the current state of knowledge relating brain changes to behavior and indicating possible future directions. © 2012 Lipina and Posner.

Lipina S.J.,CONICET | Lipina S.J.,National University of San Martín of Argentina | Posner M.I.,University of Oregon
Frontiers in Human Neuroscience | Year: 2012

Although the study of brain development in non-human animals is an old one, recent imaging methods have allowed non-invasive studies of the gray and white matter of the human brain over the lifespan. Classic animal studies show clearly that impoverished environments reduce cortical gray matter in relation to complex environments and cognitive and imaging studies in humans suggest which networks may be most influenced by poverty. Studies have been clear in showing the plasticity of many brain systems, but whether sensitivity to learning differs over the lifespan and for which networks is still unclear. A major task for current research is a successful integration of these methods to understand how development and learning shape the neural networks underlying achievements in literacy, numeracy, and attention. This paper seeks to foster further integration by reviewing the current state of knowledge relating brain changes to behavior and indicating possible future directions. © 2012 Lipina and Posner.

Journal of Physical Chemistry C | Year: 2013

In this work, we performed DFT+U periodic calculations to study the geometric and electronic properties of 12.5% Mn-doped CeO2 solid solution. The doping with Mn allowed some Mn2+ cations to substitute Ce4+ ions into the CeO2 lattice and thus drove the formation of a stable O-deficient bulk fluorite-type structure. The Mn-doped CeO2(1 1 1) surface, generated upon the cleavage of the O-deficient bulk, exhibits Mn cations in a (3+) oxidation state. Spin-polarized energy calculations and charge analysis also evidenced the effect of Mn-dopant in facilitating the creation of surface oxygen vacancies; which reflected in extended surface and subsurface ions relaxation and reduction of Mn atoms located on surface and inner cationic layers. Concerning the oxidation state of Ce, it remained unaltered as Ce4+ when an O atom was removed from the topmost anionic layer of the surface system. Reduction of a Ce4+ cation to Ce3+ was evidenced after the creation of a second surface O-vacancy. Our results indicate facilitated surface oxygen release, Mn 3+/Mn2+ redox couples formation, and promoted anionic mobility and can help to better understand the effect of Mn in enhancing Mn-doped CeO2 catalytic performance in oxidation reactions. © 2013 American Chemical Society.

Znidaric M.,National Autonomous University of Mexico | Znidaric M.,University of Ljubljana | Pineda C.,National Autonomous University of Mexico | Garcia-Mata I.,CONICET | Garcia-Mata I.,Laboratory TANDAR
Physical Review Letters | Year: 2011

The channel induced by a complex system interacting strongly with a qubit is calculated exactly under the assumption of randomness of its eigenvectors. The resulting channel is represented as an isotropic time-dependent oscillation of the Bloch ball, leading to non-Markovian behavior, even in the limit of infinite environments. Two contributions are identified: one due to the density of states and the other due to correlations in the spectrum. Prototype examples, one for chaotic and the other for regular dynamics are explored. © 2011 American Physical Society.

Eiroa E.F.,Institute Astronomia | Simeone C.,CONICET
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2013

We study circular shells in a (2+1)-dimensional background within the framework of Einstein-Born-Infeld theory. For shells around black holes we analyze the mechanical stability under perturbations preserving the symmetry. Shells around vacuum are also discussed. We find a large range in the values of the parameters compatible with stable configurations. © 2013 American Physical Society.

Catalano S.A.,CONICET | Goloboff P.A.,CONICET
Systematic Biology | Year: 2012

All methods proposed to date for mapping landmark configurations on a phylogenetic tree start from an alignment generated by methods that make no use of phylogenetic information, usually by superimposing all configurations against a consensus configuration. In order to properly interpret differences between landmark configurations along the tree as changes in shape, the metric chosen to define the ancestral assignments should also form the basis to superimpose the configurations. Thus, we present here a method that merges both steps, map and align, into a single procedure that (for the given tree) produces a multiple alignment and ancestral assignments such that the sum of the Euclidean distances between the corresponding landmarks along tree nodes is minimized. This approach is an extension of the method proposed by Catalano et al. (2010. Phylogenetic morphometrics (I): the use of landmark data in a phylogenetic framework. Cladistics. 26:539-549) for mapping landmark data with parsimony as optimality criterion. In the context of phylogenetics, this method allows maximizing the degree to which similarity in landmark positions can be accounted for by common ancestry. In the context of morphometrics, this approach guarantees (heuristics aside) that all the transformations inferred on the tree represent changes in shape. The performance of the method was evaluated on different data sets, indicating that the method produces marked improvements in tree score (up to 5% compared with generalized superimpositions, up to 11% compared with ordinary superimpositions). These empirical results stress the importance of incorporating the phylogenetic information into the alignment step. © 2012 The Author(s).

Azcoitia I.,Complutense University of Madrid | Arevalo M.-A.,Instituto Cajal | De Nicola A.F.,CONICET | Garcia-Segura L.M.,Complutense University of Madrid
Trends in Endocrinology and Metabolism | Year: 2011

Results from animal experiments showing that estradiol is neuroprotective were challenged 10 years ago by findings indicating an increased risk of dementia and stroke in women over 65 years of age taking conjugated equine estrogens. Our understanding of the complex signaling of estradiol in neural cells has recently clarified the causes of this discrepancy. New data indicate that estradiol may lose its neuroprotective activity or even increase neural damage, a situation that depends on the duration of ovarian hormone deprivation and on age-associated modifications in the levels of other molecules that modulate estradiol action. These studies highlight the complex neuroprotective mechanisms of estradiol and suggest a window of opportunity during which effective hormonal therapy could promote brain function and cognition. © 2011 Elsevier Ltd.

Madrid J.P.,Swinburne University of Technology | Donzelli C.J.,Institute Investigaciones en Astronomia Teorica y Experimental IATE | Donzelli C.J.,CONICET
Astrophysical Journal | Year: 2013

A spectroscopic follow-up of ultracompact dwarf (UCD) candidates in the fossil group NGC 1132 is undertaken with the Gemini Multi Object Spectrograph. These new Gemini spectra prove the presence of six UCDs in the fossil group NGC 1132 at a distance of D ∼ 100 Mpc and a recessional velocity of vr = 6935 ± 11 km s-1. The brightest and largest member of the UCD population is an M32 analog with a size of 77.1 pc and a magnitude of MV = -14.8 mag with the characteristics in between those of the brightest UCDs and compact elliptical galaxies. The ensemble of UCDs have an average radial velocity of 〈vr 〉 = 6966 ± 208 km s-1 and a velocity dispersion of σ v = 169 ± 18 km s-1 similar to the one of poor galaxy groups. This work shows that UCDs can be used as test particles to determine the dynamical properties of galaxy groups. The presence of UCDs in the fossil group environment is confirmed and thus the fact that UCDs can form across diverse evolutionary conditions. © 2013. The American Astronomical Society. All rights reserved..

Jakovcevic A.,CONICET | Steg L.,University of Groningen
Transportation Research Part F: Traffic Psychology and Behaviour | Year: 2013

Most Latin American countries face important environmental and societal problems associated with an increase in car traffic, and only recently, transport policies aimed at reducing these harmful consequences of car use have begun to be discussed and put on the public agenda of these countries. Surprisingly, little is known about the factors influencing the acceptability of transport policies and intentions to reduce car use in Latin America, as studies on acceptability of transport policies have typically been conducted in Europe. Previous evidence from European samples - where reducing car used had been widely discussed - showed that the Value-Belief-Norm (VBN) theory of environmentalism was an adequate theoretical framework to predict the acceptability of a transport pricing policy, as well as the intention to reduce car use when this policy would be implemented. But can these results be generalised to non-European samples? In this paper, we report results of a questionnaire study among 160 participants from Buenos Aires, Argentina, aimed to test the VBN theory. We found that the VBN theory was indeed also successful in explaining policy acceptability and intention to reduce car use in Argentina. In addition, we found support for the causal structure of the variables in VBN theory. Interestingly, biospheric and hedonic values were also directly and significantly related to feelings of moral obligation when intermediate variables were controlled for. These results suggest that normative considerations, activated by values, indeed predict policy acceptability and the intention to reduce car use in Argentina and that these considerations should be taken into account to increase the acceptability of policies aimed at reducing car use. © 2013 Elsevier B.V.

Giribet G.,CONICET
Journal of High Energy Physics | Year: 2011

We present an exact asymptotically Lifshitz black hole solution in Brans-Dicke theory of gravity in arbitrary n(≥ 3) dimensions in presence of a power-law potential. In this solution, the dynamical exponent z is determined in terms of the Brans-Dicke parameter ! and n. Asymptotic Lifshitz condition at infinity requires z > 1, which corresponds to ?(n ? 1)/(n ? 2) ≥ w ?n/(n ? 1). On the other hand, the no-ghost condition for the scalar field in the Einstein frame requires 0 < z ≤ 2(n ? 2)/(n ? 3). We compute the Hawking temperature of the black hole solution and discuss the problems encountered and the proposals in defining its thermodynamic properties. A generalized solution charged under the Maxwell field is also presented. © 2011 SISSA.

Fernandez A.,CONICET | Fernandez A.,Institute for Advanced Study
Drug Discovery Today | Year: 2014

The therapeutic opportunity for anticancer kinase inhibitors (KIs) that block cell-signaling pathways is materializing. Yet, these molecular-targeted therapies are not tailored to be allies of the immune system, and often antagonize it despite generating antigenic activity. KIs usually offer an incomplete cure and one culprit is the lack of synergy between the drug and the immune system, a problem that is magnified when the therapeutic context involves HIV-1-induced immunosuppression (AIDS). We outline a strategy to fulfill the therapeutic imperative of recruiting cooperative immune responses. Accordingly, we propose a method to redesign anticancer drugs to harness the antigenic products of drug-induced apoptosis of tumor cells, thus eliciting an adjuvant immune response. © 2014 Elsevier Ltd. All rights reserved.

Elgoyhen A.B.,CONICET | Elgoyhen A.B.,University of Buenos Aires | Langguth B.,University of Regensburg | De Ridder D.,University of Otago | Vanneste S.,University of Texas at Dallas
Nature Reviews Neuroscience | Year: 2015

Tinnitus is the perception of phantom sound in the absence of a corresponding external source. It is a highly prevalent disorder, and most cases are caused by cochlear injury that leads to peripheral deafferentation, which results in adaptive changes in the CNS. In this article we critically assess the recent neuroimaging studies in individuals with tinnitus that suggest that the disorder is accompanied by functional and structural brain abnormalities in distributed auditory and non-auditory brain regions. Moreover, we consider how the identification of the neuronal mechanisms underlying the different forms of tinnitus would benefit from larger studies, replication and comprehensive clinical assessment of patients. © 2015 Macmillan Publishers Limited.

Reynoso M.A.,CONICET | Blanco F.A.,CONICET | Bailey-Serres J.,University of California at Riverside | Crespi M.,French National Center for Scientific Research | Zanetti M.E.,CONICET
Plant Journal | Year: 2013

Translation of mRNAs is a key regulatory step that contributes to the coordination and modulation of eukaryotic gene expression during development or adaptation to the environment. mRNA stability or translatability can be regulated by the action of small regulatory RNAs (sRNAs), which control diverse biological processes. Under low nitrogen conditions, leguminous plants associate with soil bacteria and develop a new organ specialized in nitrogen fixation: the nodule. To gain insight into the translational regulation of mRNAs during nodule formation, the association of mRNAs and sRNAs to polysomes was characterized in roots of the model legume Medicago truncatula during the symbiotic interaction with Sinorhizobium meliloti. Quantitative comparison of steady-state and polysomal mRNAs for 15 genes involved in nodulation identified a group of transcripts with slight or no change in total cellular abundance that were significantly upregulated at the level of association with polysomes in response to rhizobia. This group included mRNAs encoding receptors like kinases required either for nodule organogenesis, bacterial infection or both, and transcripts encoding GRAS and NF-Y transcription factors (TFs). Quantitative analysis of sRNAs in total and polysomal RNA samples revealed that mature microRNAs (miRNAs) were associated with the translational machinery, notably, miR169 and miR172, which target the NF-YA/HAP2 and AP2 TFs, respectively. Upon inoculation, levels of miR169 pronouncedly decreased in polysomal complexes, concomitant with the increased accumulation of the NF-YA/HAP2 protein. These results indicate that both mRNAs and miRNAs are subject to differential recruitment to polysomes, and expose the importance of selective mRNA translation during root nodule symbiosis. © 2012 The Authors. The Plant Journal © 2012 Blackwell Publishing Ltd.

Zurita G.A.,CONICET | Bellocq M.I.,CONICET | Rybicki J.,Aalto University
Proceedings of the National Academy of Sciences of the United States of America | Year: 2013

The species-area relationship (SAR) gives a quantitative description of the increasing number of species in a community with increasing area of habitat. In conservation, SARs have been used to predict the number of extinctions when the area of habitat is reduced. Such predictions are most needed for landscapes rather than for individual habitat fragments, but SAR-based predictions of extinctions for landscapes with highly fragmented habitat are likely to be biased because SAR assumes contiguous habitat. In reality, habitat loss is typically accompanied by habitat fragmentation. To quantify the effect of fragmentation in addition to the effect of habitat loss on the number of species, we extend the power-law SAR to the species-fragmented area relationship. This model unites the single-species metapopulation theory with the multispecies SAR for communities. We demonstrate with a realistic simulation model and with empirical data for forest-inhabiting subtropical birds that the species-fragmented area relationship gives a far superior prediction than SAR of the number of species in fragmented landscapes. The results demonstrate that for communities of species that are not well adapted to live in fragmented landscapes, the conventional SAR underestimates the number of extinctions for landscapes in which little habitat remains and it is highly fragmented. © PNAS 2013.

In this work, we investigated for the first time the conjugation of gluconolactone to a poly(ethylene oxide)-poly(propylene oxide) block copolymer by a microwave-assisted ring opening reaction. The glucosylated copolymer was obtained with high yield (90%). A conjugation extent of approximately 100% was achieved within 15 min. The modification reduced the critical micellar concentration and increased the size of the micelles. The agglutination of the modified polymeric micelles by a soluble lectin that binds glucose confirmed the recognizability of the modified nanocarrier. Finally, the solubilization of darunavir, an anti-HIV protease inhibitor, showed a sharp increase of the aqueous solubility from 91 microgram/mL to 14.2 and 18.9 mg/mL for 10% w/v pristine and glucosylated polymeric micelles, respectively. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Rodriguez Patino J.M.,University of Seville | Pilosof A.M.R.,University of Buenos Aires | Pilosof A.M.R.,CONICET
Food Hydrocolloids | Year: 2011

Protein-polysaccharide interactions find many applications in food engineering and new food formulations. This review article describes recent research on the effect of protein-polysaccharide interactions on the properties of air-water and oil-water interfaces, as affected by their behaviour in the bulk phase. The interfacial behaviour of protein-polysaccharide mixtures exhibiting associative (i.e., net attractive) interactions as well as their performance in food emulsions and foams has been the subject of several reviews in the last decade. Much less attention has been paid to the interfacial behaviour of protein-polysaccharide mixtures exhibiting unfavourable interactions. Thus we are concerned here with the interfacial behaviour of both kinds of mixtures. © 2011 Elsevier Ltd.

Liu F.-T.,University of California at Davis | Rabinovich G.A.,CONICET
Annals of the New York Academy of Sciences | Year: 2010

Galectins, β-galactoside-binding animal lectins, are differentially expressed by various immune cells as well as a wide range of other cell types. Extracellularly, galectins are able to exhibit bivalent or multivalent interactions with cell-surface glycans on various immune cells and exert various effects. These include cytokine and mediator production, cell adhesion, apoptosis, and chemoattraction. In addition, they can form lattices with cell-surface glycoprotein receptors, resulting in modulation of receptor functions, including clustering and endocytosis. Intracellularly, galectins can participate in signaling pathways and modulate biologic responses. These include apoptosis, cell differentiation, and cell migration. Thus, a large body of literature indicates that galectins play important roles in the immune and inflammatory responses through regulating the homeostasis and functions of immune cells. The use of mice deficient in individual galectins has provided additional evidence for the contributions of these proteins to these responses. Current research indicates that galectins play important roles in the development of acute inflammation as well as chronic inflammation associated with allergies, autoimmune diseases, atherosclerosis, infectious processes, and cancer. Thus, recombinant proteins or specific galectin inhibitors may be used as therapeutic agents for inflammatory diseases. © 2009 New York Academy of Sciences.

Caceres A.,CONICET | Ye B.,University of Michigan
Current Opinion in Cell Biology | Year: 2012

In a biological sense, polarity refers to the extremity of the main axis of an organelle, cell, or organism. In neurons, morphological polarity begins with the appearance of the first neurite from the cell body. In multipolar neurons, a second phase of polarization occurs when a single neurite initiates a phase of rapid growth to become the neuron's axon, while the others later differentiate as dendrites. Finally, during a third phase, axons and dendrites develop an elaborate architecture, acquiring special morphological and molecular features that commit them to their final identities. Mechanistically, each phase must be preceded by spatial restriction of growth activity. We will review recent work on the mechanisms underlying the polarized growth of neurons. © 2012 Elsevier Ltd.

Checa S.K.,CONICET | Soncini F.C.,CONICET
Current Opinion in Biotechnology | Year: 2012

Bacterial signal-responsive regulatory circuits have been employed as platform to design and construct whole-cell bacterial biosensors for reporting toxicity. A new generation of biosensors with improved performance and a wide application range has emerged after the application of synthetic biology concepts to biosensor design. Site-directed mutagenesis, directed evolution and domain swapping were applied to upgrade signal detection or to create novel sensor modules. Rewiring of the genetic circuits allows improving the determinations and reduces the heterogeneity of the response between individual reporter cells. Moreover, the assembly of natural or engineered modules to biosensor platforms provides innovative outputs, expanding the range of application of these devises, from monitoring toxics and bioremediation to killing targeted cells. © 2012 Elsevier Ltd.

Flombaum P.,CONICET | Sala O.E.,Arizona State University
Ecology | Year: 2012

Several experiments have shown that aboveground net primary productivity increases with plant species richness. The main mechanism proposed to explain this relationship is niche complementarity, which is determined by differences in plant traits that affect resource use. We combined field and laboratory experiments using the most abundant species of the Patagonian steppe to identify which are the traits that determine niche complementarity in this ecosystem. We estimated traits that affect carbon, water, microclimate, and nitrogen dynamics. The most important traits distinguishing among species, from the standpoint of their effects on ecosystem functioning, were potential soil nitrification, rooting depth, and soil thermal amplitude. Additionally, we explored the relationship between trait diversity and aboveground net primary production (ANPP) using a manipulative field experiment. ANPP and the fraction of ANPP accounted for by trait diversity increased with number of traits. The effect of trait diversity decreased as the number of traits increased. Here, the use of traits gave us a mechanistic understanding of niche complementarity in the Patagonian steppe. © 2012 by the Ecological Society of America.

The urothelium, a specialized epithelium that covers the mucosa cell surface of the urinary bladder, undergoes dramatic morphological changes during the micturition cycle that involve a membrane apical traffic. This traffic was first described as a lysosomal pathway, in addition to the known endocytosis/exocytosis membrane recycling. In an attempt to understand the role of membrane lipid composition in those effects, we previously described the lipid-dependent leakage of the endocytosed vesicle content. In this work, we demonstrated clear differences in the traffic of both the fluid probe and the membrane-bound probe in urothelial umbrella cells by using spectrofluorometry and/or confocal and epifluorescence microscopy. Different membrane lipid compositions were established by using three diet formulae enriched in oleic acid, linoleic acid and a commercial formula. Between three and five animals for each dietary treatment were used for each analysis. The decreased endocytosis of both fluid and membrane-bound probes (approximately 32 and 49 % lower, respectively) in oleic acid-derived umbrella cells was concomitant with an increased recycling (approximately 4.0 and 3.7 times, respectively) and diminished sorting to the lysosome (approximately 23 and 37 %, respectively) when compared with the control umbrella cells. The higher intravesicular pH and the impairment of the lysosomal pathway of oleic acid diet-derived vesicles compared to linoleic acid diet-derived vesicles and control diet-derived vesicles correlate with our findings of a lower V-ATPase activity previously reported. We integrated the results obtained in the present and previous work to determine the sorting of endocytosed material (fluid and membrane-bound probes) into the different cell compartments. Finally, the weighted average effect of the individual alterations on the intracellular distribution was evaluated. The results shown in this work add evidences for the modulatory role of the membrane lipid composition on sorting of the endocytosed material. This suggests that changes in the membrane organization can be one of the underlying mechanisms for regulating the endocytosis/exocytosis processes and membrane intracellular trafficking. © 2012 Springer-Verlag Berlin Heidelberg.

Agency: European Commission | Branch: FP7 | Program: CP | Phase: ENERGY.2008.10.1.2;NMP-2008-2.6-1 | Award Amount: 2.75M | Year: 2009

At present there is no solid state hydrogen storage material available fulfilling all requirements for practical use in mobile applications. These are 1. high storage density, 2. temperatures and heats of operation compatible with PEM fuel cells, 3. high hydrogen loading and unloading speeds in the range of a few minutes and 4. low production costs. FlyHy focuses especially on the first three points while using commercially upscalable materials preparation processes. High hydrogen capacity materials like alane or borohydrides as well as so called Reactive Hydride Composites (mixtures of borohydrides with selected other hydrides), nowadays suffering from too high or too low reaction temperatures and heats, shall be modified by substituting halogens for part of the hydrogen or hydrogen containing complexes. The project partners IFE, GKSS and AU have shown that by this approach novel mixed hydrido-halogenide compounds can be prepared. Fluorine substituted Sodium Alanate exhibited drastically increased desorption pressures at the same reaction temperature or lowered reaction temperatures at the same pressure resp. Targets of the FlyHy project are (i) to exploit these findings on materials destabilisation and stabilisation resp. by halogen substitution for alane, borohydrides and Reactive Hydride Composites , in order to achieve a breakthrough in the thermodynamic properties of these materials exhibiting the highest hydrogen capacities known at present, (ii) to obtain an in depth scientific understanding of the sorption properties of the substituted materials by extended structural and thermodynamical characterisation and modelling, for materials optimisation, (iii) determine tank relevant materials properties like e.g. densification behaviour and heat conductivity, and, if applicable, do first tests in a prototype tank.

Agency: European Commission | Branch: FP7 | Program: CP-SICA | Phase: ENV.2007. | Award Amount: 4.28M | Year: 2008

The CLARIS LPB Project aims at predicting the regional climate change impacts on La Plata Basin (LPB) in South America, and at designing adaptation strategies for land-use, agriculture, rural development, hydropower production, river transportation, water resources and ecological systems in wetlands. In order to reach such a goal, the project has been built on the following four major thrusts. First, improving the description and understanding of decadal climate variability is of prime importance for short-term regional climate change projections (2010-2040). Second, a sound approach requires an ensemble of coordinated regional climate scenarios in order to quantify the amplitude and sources of uncertainties in LPB future climate at two time horizons: 2010-2040 for adaptation strategies and 2070-2100 for assessment of long-range impacts. Such coordination will allow to critically improve the prediction capacity of climate change and its impacts in the region. Third, adaptation strategies to regional scenarios of climate change impacts require a multi-disciplinary approach where all the regional components (climate, hydrology, land use, land cover, agriculture and deforestation) are addressed in a collaborative way. Feedbacks between the regional climate groups and the land use and hydrology groups will ensure to draw a first-order feedback of future land use and hydrology scenarios onto the future regional climate change. Fourth, stakeholders must be integrated in the design of adaptation strategies, ensuring their dissemination to public, private and governmental policy-makers. Finally, in continuity with the FP6 CLARIS Project, our project will put a special emphasis in forming young scientists in European institutes and in strengthening the collaborations between European and South American partners. The project is coordinated with the objectives of LPB, an international project on La Plata Basin that has been endorsed by the CLIVAR and GEWEX Panels.

Agency: European Commission | Branch: FP7 | Program: CSA-SA | Phase: HEALTH-2007-4.1-8 | Award Amount: 925.80K | Year: 2008

Background Tuberculosis and HIV/AIDS are on the rise worldwide, representing a global public health problem with considerable mutual interaction: TB is the leading cause of mortality for people living with HIV/AIDS, and HIV is the most potent force driving the TB epidemic in countries with a high prevalence of HIV . Especially in rural areas of Africa, Latin America, India and Russia both diseases form a deadly combination affecting large populations: In 2006, 39.5 million people suffered from HIV , and 2 billion people were infected with Mycobacterium tuberculosis, the causative agent of TB . Approximately 11 million people are co-infected with both diseases. Up to now, there is a massive failure to respond to the dual epidemic in an integrated way , and despite an increasing awareness worldwide, greater commitment and increased funding, current prevention and treatment efforts as well as coordinated research initiatives need to be strengthened to address the challenge of TB-HIV coinfection . TB and HIV programmes worldwide still work largely in isolation from each other and are focussing on national levels, although the urgent need to combat HIV and TB is recognized internationally. Additionally, scientists still primarily work with colleagues from the same field of research instead of collaborating with partners in complementary fields. Objective The objective of the support action is to provide an overview of the state of the art in HIV and TB research and disease management in the different partner countries, to identify global research priorities and to boost international cooperation between leading HIV and TB experts from Europe and those countries mainly affected by the two diseases - Russia, Latin America, South Africa and India.

Agency: European Commission | Branch: FP7 | Program: CP-TP | Phase: KBBE.2011.1.2-04 | Award Amount: 4.89M | Year: 2012

ADAPTAWHEAT will show how flowering time variation can be exploited for the genetic improvement of the European wheat crop to optimise adaptation and performance in the light of predicted climate change. It will test current hypotheses that postulate specific changes in ear emergence and the timing and duration of developmental phases, which are thought of as components of ear emergence, will improve wheat productivity. Precise genetic stocks varying in specific flowering time elements and subjected to genotyping and characterisation with diagnostic markers for key flowering time genes will be used to test these hypotheses. They will be phenotyped at the molecular (transcript abundance), physiological (growth stage dissection) and agronomic (yield components) levels in multiple field trials located at sites in Europe that represent regional agricultural diversity and at non European locations that have mega environments of relevance. Controlled environment experiments will investigate specific environmental interactions including day length, ambient temperature, and heat stress. Data analysis will aid the construction of new wheat flowering models that can be used to refine existing hypotheses. They will allow standing genetic variation for flowering time in European germplasm to be deployed more efficiently in wheat breeding programmes. This knowledge will be used to inform searches for specific phenotypic and molecular variants in diverse and non adapted wheat germplasm panels provided by consortium members. Vital novel genetic variation will be efficiently imported into the germplasm of European wheat breeders. The project will deliver new diagnostic markers for genotyping, molecular reporters for novel breeding selection strategies and the tools and knowledge necessary for a combined physiology and genomics led predictive wheat breeding programme. A conduit for these outcomes will be three SMEs, who will exploit the tools developed to deliver these outcomes.

This paper analyses firms' drivers for linking to public research organisations (PRO) (first goal) and compares perceptions and behaviours of linked vs. unlinked firms (second goal). We used an original firm database constructed from a representative survey with information for linked and unlinked firms for year 2005 in Argentina. Drivers were estimated using a Probit model, while differences in perceptions and behaviours between linked and unlinked firms were assessed with propensity score matching techniques. For our first goal we found that (i) firms' knowledge bases were not drivers for linking to PRO and (ii) networking capabilities matter but there is a substitution effect between interacting with PRO and interacting with other economic agents in the market when firms aim at exchanging information rather than doing joint research. These findings may imply that current linkages are not exploiting properly their knowledge potential; it may be worth designing a division of labour among PRO in their functions in PROindustry interactions. For our second goal: we found that (i) linked firms invest more in innovative activities; (ii) they are more prone to patenting; (iii) both groups of firms value similarly PRO research outputs available at arm length (i.e. without direct linking). Given the asymmetric development on appropriability tools between PRO and firms and the fact that all firms benefit from PRO research outputs, the higher predisposition of linked firms towards patenting, suggests that special attention should be placed at analysing the risks of a private appropriation of publicly created knowledge. © 2011 Elsevier Ltd. All rights reserved.

Prado H.J.,University of Buenos Aires | Matulewicz M.C.,CONICET
European Polymer Journal | Year: 2014

Cationic polysaccharides are widely used in diverse areas such as water treatment, papermaking, chemical, food, cosmetic, and petroleum industries. The combination of cationic polysaccharides with anionic polymers can lead to interpolyelectrolyte complexes with hydrogel-like structures further expanding the application of the former. The aim of the present review is to fill a gap on the literature about cationization reactions of different polysaccharides and to offer a systematic and up-to-date analysis on the subject. Polysaccharides such as starch, dextran, cellulose and its derivatives, hemicellulose, pectin, chitosan, and seaweed polysaccharides among others are considered. Cationized polysaccharides can be prepared by reaction with various reagents. The main focus is on the substitution with dialkylamino hydroxypropyl and trialkylammonium hydroxypropyl ethers, being that the most common modifications involve the introduction of the 2-hydroxy-3-(trimethylammonium)propyl group by reaction of the polysaccharide with 2,3-epoxypropyltrimethylammonium chloride in an alkaline solution. An alternative to this method involves generation of the reagent in situ from 3-chloro-2-hydroxypropyltrimethylammonium chloride. In addition, polysaccharides substituted with other type of cationic groups and amphoteric derivatives are presented. Different methods of analysis, toxicological studies and applications of the modified polymers are also included. © 2013 Elsevier B.V.

Generalized frosts (GF) in central-southern South America have a strong impact due to their spatial extension, and they are especially important when they become persistent. This paper aims at identifying the atmospheric circulation features that determine the extreme GF persistence, i. e. very persistent and without persistence, and the differences between them, during the 1961-1990 winters. Since the GF without persistence group outnumbers the other one, two subgroups are composed with events selected from winters with maximum and minimum frequency of GF occurrence, respectively. Additionally, the individual event of July 1988 within the very persistent GF group is analyzed due to its exceptional persistence. GF persistence is mainly conditioned by two large-scale dynamic factors. One is the Rossby wave train propagation across the Pacific Ocean, and the other one is the location with respect to the continent and the magnitude of the confluence in the jet entrance region in subtropical latitudes. A predominantly meridional Rossby wave train propagation with a confluence region to the west of the continent prior to the event favors GF with intermediate (null) persistence depending on the greater (lesser) jet acceleration. This is conditioned by the magnitude of the confluence, which, in turn, depends on the disposition of the wave train propagation pattern. Instead, an essentially zonal propagation with a confluence region to the east of the continent favors the GF persistence for several days, yet if there is no confluence the event does not persist. The greatest persistence of an event combines the confluence/diffluence of the jet entrance/exit region, which depends on the disposition with respect to the continent of the zonally propagating Rossby wave trains. © 2011 Springer-Verlag.

Leon A.E.,CONICET | Mauricio J.M.,University of Seville | Solsona J.A.,CONICET
IEEE Transactions on Energy Conversion | Year: 2012

A control strategy is proposed to enhance the operation, under network disturbances, of a wind turbine driven doubly fed induction generator (DFIG). The scheme allows us to overcome low voltages, imbalances, and harmonic distortions at the point of common coupling. The control law is designed using a feedback linearization approach plus resonant filters; this law directly controls the DFIG stator powers from the rotor voltages, unlike the most used nested two-loop approaches. An accurate control of the active and reactive powers delivered to the grid permits us to fulfill severe grid code requirements and to improve the fault ride-through capability. Under unbalanced conditions, the reference currents of both grid- and rotor-side converters are coordinately chosen to simultaneously eliminate the double-frequency pulsations in the total active power and electromagnetic torque. Several tests and disturbances to provide a realistic assessment and validation have been performed, showing the adequacy of the proposed controller. Comparisons with other control approaches with different objectives are also presented to illustrate the advantages regarding elimination of the double-frequency ripples and harmonic rejection capability. © 2012 IEEE.

Agency: European Commission | Branch: FP7 | Program: CP-IP-SICA | Phase: ENV.2010.4.1.3-2 | Award Amount: 9.15M | Year: 2010

The overall goal of the proposed project is to develop a coordinated global observation system for mercury able to provide temporal and spatial distributions of mercury concentrations in ambient air and precipitation over land and over surface waters at different altitudes and latitudes around the world. This will then provide high quality data for the validation and application of regional and global scale atmospheric models, to give to governments, national and international organisations and stakeholders a firm basis for future policy development and implementation. Specific objectives of the proposed project are (a) to establish a Global Observation System for Mercury (GMOS) able to provide ambient concentrations and deposition fluxes of mercury species around the world, by combining observations from permanent ground-based stations, and from oceanographic and tropospheric measurement campaigns; (b) to validate regional and global scale atmospheric mercury modelling systems able to predict temporal variations and spatial distributions of atmospheric mercury entering to and re-emitted from terrestrial and aquatic receptors; (c) to evaluate and identify source-receptor relationships at country scale and their temporal trends for current and projected scenarios of mercury emissions from anthropogenic and natural sources; (d) to develop interoperable tools to allow the sharing of observational and models output data produced by GMOS. The overarching goal of GMOS is to support the achievement of goals set by the GEO / GEOSS, and specifically of the GEO Task HE-09-02d and contribute to the advancement of our scientific understanding in the nine Societal Benefit Areas (SBA) established in GEOSS. The proposed project will rely on the results and knowledge acquired in the framework of past EU projects (i.e., MAMCS, MOE, MERCYMS) and international programs (i.e., UNECE TF HTAP; UNEP F&T partnership area).

News Article | February 25, 2017
Site: www.scientificamerican.com

Attitudes about marijuana seem to be changing and diversifying in Latin America. Throughout the 20th century its consumption was associated with criminal behavior. But over the last decade the drug's image has improved in some countries. A new survey reveals that in some Latin countries more than 40 percent of the population is in favor of legalizing marijuana, although in other countries favor remains low. “Until now, the scientific literature showed that Latin America had a consistent position on decriminalization,” says lead author Andrés Mendiburo Seguel, a sociologist at the University of Santiago, Chile. “Our work points out that there are differences of opinion that could influence future public policies adopted in the region.” The survey was conducted by Mendiburo Seguel and researchers at Andrés Bello National University of Chile and the University of London, and was published in the International Journal of Drug Policy. The researchers interviewed 8,952 adults in large cities in nine Latin American countries: Argentina, Uruguay, Chile, Bolivia, Mexico, Peru, Costa Rica, Colombia and El Salvador. More than 40 percent of the populations of Chile, Colombia, Uruguay and Mexico are in favor of legalizing marijuana whereas in El Salvador and Bolivia that number did not exceed 10 percent. The survey also assessed the acceptance of recreational marijuana use, with favorable responses in Uruguay (68 percent), Mexico (57 percent) and Costa Rica (55 percent). Less support for such use was reported in Peru (44 percent), El Salvador (31 percent) and Bolivia (30 percent). In all countries acceptance of medicinal marijuana use, either to treat pain or epilepsy, was greater than for recreational use. “There is a correlation between the countries that most disagree with the legalization of marijuana and their level of human development. The most conservative, such as Bolivia, Peru and El Salvador have a lower level of development. They are also countries where illegal drug trafficking is a big problem. The more liberal nations, such as Uruguay and Chile, reached a better level,” according to the researchers. Yet, this is not the only possible interpretation, says Ricardo Pautassi, a researcher at the Mercedes and Martin Ferreyra Institute for Medical Research, CONICET, in Argentina, who did not participate in the survey. “The differences of opinion have to do with which public policies are being carried out in their countries. The human development index has some correlation with income, which promotes access to marijuana use. This in turn tends to facilitate positive views toward legalization for recreational and therapeutic use.” Indeed, all nine nations have enacted laws that make it a crime to produce and distribute drugs, but laws around consumption vary widely. In Bolivia, Colombia and El Salvador, for example, using marijuana is still a criminal offense. Argentina’s Supreme Court decided in 2009 that the punishment for marijuana possession without distribution to third parties was unconstitutional. In Mexico consumption of small amounts was decriminalized whereas in Uruguay personal consumption was never a crime, although in 2013 the country passed a law allowing the production and sale of marijuana in amounts regulated by the state. “We have registered 5,864 people growing cannabis, and 33 clubs with up to 45 members who are also involved in the cultivation, processing and distribution,” says Héctor Suárez, head of the Uruguayan Drug Observatory. “You can’t advertise the product but it will be sold in pharmacies in the coming months. In this way social and sanitary support is given to people with problematic consumption, while illegal drug trafficking is avoided,” he adds. Chile is debating the decriminalization of pot for recreational use, and in 2014 a pilot project for cultivating and distributing marijuana for medicinal purposes was authorized. Last December Colombia passed a law enabling marijuana for medicinal use. Peru has authorized up to eight grams of marijuana for personal use. In Costa Rica the use and possession of drugs for personal use is not considered a crime but it is not yet clear whether growing the plant for personal use is accepted. The questionnaire also measured risk perception. On average, except in Bolivia, El Salvador and Peru, most people believe tobacco and alcohol are more harmful than marijuana. “The overall assessment is correct based on studies conducted in the U.K. While it is not harmless, marijuana causes less harm and involves less risk of dependence than alcohol, tobacco and drugs such as benzodiazepines (which are prescribed as sedatives), cocaine and heroin," says Enzo Tagliazucchi, an addiction researcher at the Netherlands Institute for Neuroscience.

News Article | November 16, 2016
Site: www.sciencemag.org

Scientists in Argentina are bracing for hard times next year. Later this month, the country’s senate is expected to approve a 2017 budget that would deal a crippling blow to research. Researchers and students have been staging protests in the capital, Buenos Aires, and in other cities since news of the pending cuts broke last month. “The message is clear: Science is not a priority to this government,” says Cecilia Kramar, an Argentinian postdoc studying neuroscience at the University of Western Ontario in London. “There won’t be new science in Argentina because there won’t be new scientists to do it.” When Argentine President Mauricio Macri took office in December 2015, he vowed to double the share of spending on science and technology in the government’s budget from 0.7% to 1.5%. But that promise has collided with an economic downturn that is driving up the nation’s debt. As part of its plan for balancing its books, the government intends to cut the science and technology budget by $198 million, to $2.1 billion in 2017—an 8.5% decrease. Belt-tightening will be felt especially severely at the National Scientific and Technical Research Council (CONICET), which will have to devote 96% of its $655 million budget next year to salaries for researchers and scholars. That leaves a mere $26 million for research projects, lab equipment, and scholarships. (In 2014, CONICET spent $77 million—31% of its budget that year—on items other than salaries.) Argentina’s young Ph.D. scientists and postdocs rely on CONICET stipends as a bridge to tenure-track positions in academia or other career paths. Young researchers now on stipends are expected to be OK. But “it is not clear whether [CONICET] will have the sufficient funds to open new positions,” warns Jorge Aliaga, a physicist and former dean of the Faculty of Exact and Natural Sciences at the University of Buenos Aires. That could cast many young researchers adrift. For that reason, Aliaga and others worry that the expected cuts will spark an exodus of young scientific talent. Argentina has experienced brain drains before—most recently in the early 2000s, when the country’s economy was in a severe recession. “Whole packs of young people just left,” Aliaga says. Echoing that concern is Franco Bonafé, a Ph.D, student who is studying quantum dynamics at the National University of Córdoba. In 2013, he turned down a chance to enroll in a Ph.D. program at the University of Texas in Austin. “I said, ‘I’ll take a chance here in Argentina,’” he recalls. But the cuts have cast a shadow over his future. If the outlook for science here remains bleak, he says, “I will have no chance whatsoever to become the chemist that I want to be.” Kramar, meanwhile, is one of almost 7000 Argentinian scientists now living outside of the country, according to the science ministry. It has always been her plan to return to Argentina. “I’m not changing my mind,” she says. “But even if I shout and kick, [the government] will be shutting the doors on me. I won’t be able to return home.”

Reynoso M.M.,National and Kapodistrian University of Athens | Reynoso M.M.,CONICET
Astronomy and Astrophysics | Year: 2014

Context. Gamma-ray bursts (GRB) are the most powerful events in the universe. They are capable of accelerating particles to very high energies, so are strong candidates as sources of detectable astrophysical neutrinos. Aims. We study the effects of particle acceleration and escape by implementing a two-zone model in order to assess the production of high-energy neutrinos in GRBs associated with their prompt emission. Methods. Both primary relativistic electrons and protons are injected in a zone where an acceleration mechanism operates and dominates over the losses. The escaping particles are re-injected in a cooling zone that propagates downstream. The synchrotron photons emitted by the accelerated electrons are taken as targets for pγ interactions, which generate pions along with the pp collisions with cold protons in the flow. The distribution of these secondary pions and the decaying muons are also computed in both zones, from which the neutrino output is obtained. Results. We find that for escape rates lower than the acceleration rate, the synchrotron emission from electrons in the acceleration zone can account for the GRB emission, and the production of neutrinos via pγ interactions in this zone becomes dominant for Eν > 105 GeV. For illustration, we compute the corresponding diffuse neutrino flux under different assumptions and show that it can reach the level of the signal recently detected by IceCube. © 2014 ESO.

Croci D.O.,CONICET | Cerliani J.P.,CONICET | Dalotto-Moreno T.,CONICET | Mendez-Huergo S.P.,CONICET | And 13 more authors.
Cell | Year: 2014

The clinical benefit conferred by vascular endothelial growth factors (VEGF)-targeted therapies is variable, and tumors from treated patients eventually reinitiate growth. Here, we identify a glycosylation-dependent pathway that compensates for the absence of cognate ligand and preserves angiogenesis in response to VEGF blockade. Remodeling of the endothelial cell (EC) surface glycome selectively regulated binding of galectin-1 (Gal1), which upon recognition of complex N-glycans on VEGFR2, activated VEGF-like signaling. Vessels within anti-VEGF-sensitive tumors exhibited high levels of α2-6-linked sialic acid, which prevented Gal1 binding. In contrast, anti-VEGF refractory tumors secreted increased Gal1 and their associated vasculature displayed glycosylation patterns that facilitated Gal1-EC interactions. Interruption of β1-6GlcNAc branching in ECs or silencing of tumor-derived Gal1 converted refractory into anti-VEGF-sensitive tumors, whereas elimination of α2-6-linked sialic acid conferred resistance to anti-VEGF. Disruption of the Gal1-N-glycan axis promoted vascular remodeling, immune cell influx and tumor growth inhibition. Thus, targeting glycosylation-dependent lectin-receptor interactions may increase the efficacy of anti-VEGF treatment. PaperFlick © 2014 Elsevier Inc.

Rostagno C.M.,CONICET | Degorgue G.,Institute Cooperacion Economica Internacional ICEI
Geomorphology | Year: 2011

Desert pavements are prominent features of many geomorphic surfaces in arid and semiarid lands. In the semiarid soils of north-eastern Patagonia, gravel cover in the shrub interspace areas of shrub-dominated communities is generally high, and contrast with that of grass-dominated patches where gravel cover is either absent or negligible. In the present study we analyze the relationship between soil erosion and desert pavement formation, in three sites, the upper, middle and lower slope positions of a flank pediment where well-conserved soils served as reference areas. We used the gravel cover and mass, as well as the thickness of the remnant A horizon, as determined by the depth of the Bt horizon of a Xeric Calciargid, as measures of soil erosion. Surface gravel at four cardinal points in respect to mounds associated with shrub-clumps was collected and the depth to the Bt horizon was determined. The mean thickness of the A horizon in the well-conserved soils were 11.3, 10.0 and 13.5cm for the upper, middle and lower slope positions, respectively. For the same positions, the mean coarse fragment contents (>2.0mm) in the 0-10cm depth of the A horizon in the well-conserved soils were 144, 92 and 119gkg-1, and the mean surface gravel mass in the eroded patches were 5.3, 3.1 and 4.7kgm-2. Surface gravel mass and depth of the remnant A horizon gave different estimates of the magnitude of soil erosion in the flank pediment. Thus, the mean/maximum soil loss, as determined by the mean gravel mass on the soil surface for the upper, middle and lower slope positions were, 28.3/68.2, 27.0/63.8 and 31.5/56.4mm, respectively. These figures increased to a mean of 50.0, 52.5 and 82.0mm for the same positions when soil loss was determined as the difference between the thickness of the A horizon of the well-conserved soil and that of the remaining A horizon in eroded patches. The loss of the A horizon by wind and water erosion seems to initiate the change from grass steppe to a stable shrub steppe characterized, in the shrub interspaces, by well-developed desert pavements. The strong correlation between surface gravel mass and the thickness of the remaining A horizon indicates that accelerated soil erosion has played an important role in the formation of desert pavements, and that desert pavements are good indicators of the extent and intensity of the erosion process in the Punta Ninfas area. © 2011 Elsevier B.V.

Avale M.E.,King's College London | Avale M.E.,CONICET | Rodriguez-Martin T.,King's College London | Gallo J.-M.,King's College London
Human Molecular Genetics | Year: 2013

Abnormal metabolism of the tau protein is central to the pathogenesis of a number of dementias, including Alzheimer's disease. Aberrant alternative splicing of exon 10 in the tau pre-mRNA resulting in an imbalance of tau isoforms is one of the molecular causes of the inherited tauopathy, FTDP-17. We showed previously in heterologous systems that exon 10inclusion in tau mRNA could be modulated by spliceosome-mediated RNA trans-splicing (SMaRT). Here, we evaluated the potential of trans-splicing RNA reprogramming to correct tau mis-splicing in differentiated neurons in a mouse model of taumis-splicing, the htau transgenic mouse line, expressing the human MAPT gene in a null mouse Mapt background.Trans-splicing molecules designed to increase exon 10 inclusion were delivered to neurons using lentiviral vectors. We demonstratereprogramming of tau transcripts at the RNA level after transduction of cultured neurons or after direct delivery and long-term expression of viral vectors into the brain of htau mice in vivo. Tau RNA trans-splicing resulted in an increasein exon 10 inclusion in the mature tau mRNA. Importantly, we also show that the trans-spliced product is translated into a full-length chimeric tau protein. These results validate the potential of SMaRT to correct tau mis-splicing and provide a framework for its therapeutic application to neurodegenerative conditions linked to aberrant RNA processing. © The Author 2013.

Gonzalez A.D.,CONICET | Frostell B.,KTH Royal Institute of Technology | Carlsson-Kanyama A.,Swedish Defence Research Agency
Food Policy | Year: 2011

The production, transport and processing of food products have significant environmental impacts, some of them related to climate change. This study examined the energy use and greenhouse gas emissions associated with the production and transport to a port in Sweden (wholesale point) of 84 common food items of animal and vegetable origin. Energy use and greenhouse gas (GHG) emissions for food items produced in different countries and using various means of production were compared. The results confirmed that animal-based foods are associated with higher energy use and GHG emissions than plant-based foods, with the exception of vegetables produced in heated greenhouses. Analyses of the nutritional value of the foods to assess the amount of protein delivered to the wholesale point per unit energy used or GHG emitted (protein delivery efficiency) showed that the efficiency was much higher for plant-based foods than for animal-based. Remarkably, the efficiency of delivering plant-based protein increased as the amount of protein in the food increased, while the efficiency of delivering animal-based protein decreased. These results have implications for policies encouraging diets with lower environmental impacts for a growing world population. © 2011 Elsevier Ltd.

Sustaita D.,University of Connecticut | Pouydebat E.,CNRS Mechanical Adaptation and Evolution | Manzano A.,CONICET | Abdala V.,CONICET | And 2 more authors.
Biological Reviews | Year: 2013

Human beings have been credited with unparalleled capabilities for digital prehension grasping. However, grasping behaviour is widespread among tetrapods. The propensity to grasp, and the anatomical characteristics that underlie it, appear in all of the major groups of tetrapods with the possible exception of terrestrial turtles. Although some features are synapomorphic to the tetrapod clade, such as well-defined digits and digital musculature, other features, such as opposable digits and tendon configurations, appear to have evolved independently in many lineages. Here we examine the incidence, functional morphology, and evolution of grasping across four major tetrapod clades. Our review suggests that the ability to grasp with the manus and pes is considerably more widespread, and ecologically and evolutionarily important, than previously thought. The morphological bases and ecological factors that govern grasping abilities may differ among tetrapods, yet the selective forces shaping them are likely similar. We suggest that further investigation into grasping form and function within and among these clades may expose a greater role for grasping ability in the evolutionary success of many tetrapod lineages. © 2013 Cambridge Philosophical Society.

Landau S.J.,CONICET | Scoccola C.G.,Institute of Astrophysics of Canarias | Scoccola C.G.,University of La Laguna | Sudarsky D.,National Autonomous University of Mexico
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2012

We briefly review an important shortcoming-unearthed in previous works-of the standard version of the inflationary model for the emergence of the seeds of cosmic structure. We consider here some consequences emerging from a proposal inspired on ideas of Penrose and Diósi about a quantum-gravity induced reduction of the wave function, which has been put forward to address the shortcomings, arguing that its effect on the inflaton field is what can lead to the emergence of the seeds of cosmic structure. The proposal leads to a deviation of the primordial spectrum from the scale-invariant Harrison-Zel'dovich one, and consequently, to a different CMB power spectrum. We perform statistical analyses to test two quantum collapse schemes with recent data from the CMB, including the 7-yr release of WMAP and the matter power spectrum measured using LRGs by the Sloan Digital Sky Survey. Results from the statistical analyses indicate that several collapse models are compatible with CMB and LRG data, and establish constraints on the free parameters of the models. The data put no restriction on the timescale for the collapse of the scalar field modes. © 2012 American Physical Society.

Epele M.,CONICET | Llubaroff R.,University of Buenos Aires | Sassot R.,University of Buenos Aires | Stratmann M.,Brookhaven National Laboratory
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2012

We present a detailed assessment of uncertainties in parton-to-pion and parton-to-kaon fragmentation functions obtained in recent global QCD analyses of single-inclusive hadron production data at next-to-leading order accuracy. We use the robust Lagrange multiplier approach for determining uncertainties to validate the applicability of the simpler but approximate Hessian method. Extensive comparisons of the results obtained within both methods are presented for the individual parton-to-pion and kaon fragmentation functions. We provide Hessian eigenvector sets of pion and kaon fragmentation functions that allow one to easily propagate their uncertainties to any observable. Various applications of these sets are presented for pion and kaon production in electron-positron annihilation, lepton-nucleon scattering, and proton-proton collisions. © 2012 American Physical Society.

Molina J.M.,CONICET | Cazorla A.L.,National University of the South
Journal of Sea Research | Year: 2011

Mustelus schmitti is an endangered endemic shark of the southwest Atlantic, and an important economical resource in Argentina, Brazil and Uruguay. The objective of this study was to describe the trophic ecology of M. schmitti in Anegada Bay, its feeding strategy and diet composition, along with the possible dietary shifts, due to season, sex, ontogeny and the different geographical features of the bay. Our results show that M. schmitti is a carnivorous opportunistic predator, feeding on a variety of benthic invertebrates. The diet presented seasonal and ontogenetic variations, while no differences in diet composition were observed between sexes or the different sampling sites. This species behave as a generalize feeder, with a wide trophic spectrum and a diverse diet. © 2011 Elsevier B.V.

Podhajcer O.L.,CONICET | Miriuka S.,Foundation for the Fight Against Neurological Infant Diseases FLENI
Cell Stem Cell | Year: 2010

To foster stem cell science in South America, a collaborative meeting on scientific and bioethical aspects of stem cell clinical translation was held in November, 2009, in Buenos Aires, Argentina, cosponsored by the International Society for Stem Cell Research. © 2010 Elsevier Inc. All rights reserved.

Garate H.,CONICET | Mondragon I.,University of the Basque Country | D'Accorso N.B.,CONICET | Goyanes S.,CONICET
Macromolecules | Year: 2013

We report an investigation of the mechanisms involved in the formation of nanostructured epoxy thermosetting systems using highly epoxidized poly(styrene-b-isoprene-b-styrene) (eSIS) block copolymer at three different stages of the curing process. In the uncured state, polystyrene (PS) blocks self-assembled in sphere-like nanodomains with a short-range order, while epoxidized polyisoprene (ePI) subchains were initially miscible with the epoxy precursors. As the curing reaction proceeded, the PS nanodomains became gradually distorted switching to bigger and less organized structures. This effect is due to reaction-induced microphase separation of ePI subchains which became immiscible with the epoxy system as the curing process occurs. However, this demixing process was partial because of the reaction between ePI subchains and the epoxy matrix, which reduced ePI subchains mobility. Non expulsed ePI fraction increased the epoxy matrix mean glass transition temperature (T g) in (20-25) C. Moreover, it was demonstrated that the epoxidation degree of ePI subchains affected the final obtained nanostructured pattern of the thermosetting materials, switching from distorted and interconnected sphere-like nanodomains when the epoxidation degree is 65% to sphere-like nanostructures for 100% of epoxidation. © 2013 American Chemical Society.

Chierchie F.,CONICET | Paolini E.E.,National University of the South
IEEE Transactions on Circuits and Systems I: Regular Papers | Year: 2013

A discrete-time pulse width modulator (PWM) with zero baseband distortion for arbitrary band-limited modulating signals is developed in this paper. It is based on adjusting the duty-cycles of the PWM such that the samples of an ideal low-pass filtered version of the PWM signal coincide with the discrete-time samples of the modulating signal. Elaborating on previous approaches in the literature, it is shown that this problem can be stated as a multidimensional inverse function approach, and therefore it can be solved using iterative methods. Starting with the duty-cycle values of a uniform PWM, the successive iterations provide slight duty-cycle corrections that, in the limit, result in zero baseband distortion even for low carrier-to-modulating frequency ratios. Aiming at a practical, real-time implementation two new results are provided. First, explicit bounds on the improvement achievable after each duty-cycle correction are derived. Second, a block processing architecture suitable for real-time implementation is proposed, and the increase of distortion caused by its use is quantified. Several examples with typical band-limited signals demonstrate the performance of the algorithm. © 2013 IEEE.

Tissera P.B.,CONICET | Tissera P.B.,Institute Astronomia y Fisica del Espacio | Scannapieco C.,Leibniz Institute for Astrophysics Potsdam | Beers T.C.,National Optical Astronomy Observatory | Carollo D.,Macquarie University
Monthly Notices of the Royal Astronomical Society | Year: 2013

We investigate the chemical and kinematic properties of the diffuse stellar haloes of six simulated Milky-Way-like galaxies from the Aquarius Project. Binding energy criteria are adopted to define two dynamically distinct stellar populations: the diffuse inner and outer haloes, which comprise different stellar subpopulations with particular chemical and kinematic characteristics. Our simulated inner- and outer-halo stellar populations have received contributions from debris stars (formed in subgalactic systems while they were outside the virial radius of the main progenitor galaxies) and endo-debris stars (those formed in gas-rich subgalactic systems inside the dark matter haloes of the main progenitor galaxy). The inner haloes possess an additional contribution from disc-heated stars, in the range ~3-30 per cent, with a mean of ~20 per cent. Disc-heated stars might exhibit signatures of kinematical support, in particular among the youngest ones. Endo-debris plus disc-heated stars define the so-called in situ stellar populations. In both the inner- and outer-halo stellar populations, we detect contributions from stars with moderate to low [α/Fe] ratios, mainly associated with the endo-debris or disc-heated subpopulations. The observed abundance gradients in the inner-halo regions are influenced by both the level of chemical enrichment and the relative contributions from each stellar subpopulation. Steeper abundance gradients in the inner-halo regions are related to contributions from the disc-heated and endo-debris stars, which tend to be found at lower binding energies than debris stars. In the case of the outer-halo regions, although [Fe/H] gradients are relatively mild, the steeper profiles arise primarily due to contributions from stars formed in more massive satellites, which sink farther into the main halo system, and tend to have higher levels of chemical enrichment and lower energies. Our findings support the existence of (at least) two distinct diffuse stellar halo populations, as suggested by a number of recent observations in the MilkyWay and M31. Our results also indicate that a comparison of the range of predicted kinematics, abundance gradients and frequency of [α/Fe]-deficient stars with observations of these quantities in the Milky Way, M31 and other large spirals can both provide clues to improve the modelling of baryonic physics, and reveal detailed information about their likely history of formation and evolution. © 2013 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society.

Agency: European Commission | Branch: FP7 | Program: MC-ITN | Phase: FP7-PEOPLE-ITN-2008 | Award Amount: 4.65M | Year: 2009

European scientists lead the world in the modelling of the formation of cosmic structures using computer simulations. The objective of the CosmoComp proposal is to reinforce Europes world standing in this field by training the next generation of computational cosmologists. CosmoComp builds on and extends existing research collaborations between major European centres, and has a global element with links to Latin America and the Far East. New training capacity will be developed through the network activities, which will benefit early stage researchers from across Europe, beyond the network members. We propose a series of ground breaking ``grand-challenge simulations which use the state of the art numerical techniques in the subject on some of the largest supercomputers available in Europe. Sun Microsystems and Microsoft will actively participate in our training programme, ensuring that CosmoComp will prepare young people for a research career in academia or industry.

Bearzotti L.A.,Andrés Bello University | Salomone E.,CONICET | Chiotti O.J.,GIDSTAD UTN FRSF
International Journal of Production Economics | Year: 2012

Organizations have made a significant effort to implement software for planning and scheduling, but disruptive event management is still a problem to be solved. Since a disruptive event can affect the overall performance of the supply chain, SCEM (Supply Chain Event Management) systems presenting different automation levels such as monitoring, alarm and decision support have been proposed. However, the management of disruptive events, taking into account the distributed nature of the supply chain, the members autonomy and the ability to exert corrective control actions, has been identified as a problem that requires further research. This work presents an agent-based approach for the SCEM problem, which can perform autonomous corrective control actions to minimize the effect of deviations in the plan that is currently being executed. These control actions consist of a distribution of the variation between supply chain members, using the plans slack in a collaborative way. An innovative feature of this approach is its focus on resources, which are affected by disruptive events in a direct way. Based on this approach, a SCEM system is designed as a net of control points defined on resources connected through supply process orders. Two novel aspects are the distributed collaborative inter-organizational architecture of the SCEM system and a Double Contract Net Protocol. This protocol allows a set of resource:representing agents to interact through an agent, representing a supply process order as a mediator. An application to a case study of the Multi-Agent SCEM system implemented with JADE is provided. © 2010 Elsevier B.V. All rights reserved.

Inis Biotech Llc, Conicet, Fundacion Instituto Leloir Fil and Asociacion Civil De Estudios Superiores Aces | Date: 2014-09-05

The invention relates to the identification of Secreted Protein, Acidic and Rich in Cysteine (SPARC) as a new therapeutic target in patients with fulminant hepatitis and allows the development of a strategy destined to protect the liver form damage. The invention relates to the treatment of acute liver failure or fulminant hepatitis by administering to a subject in need thereof an agent that inhibits at least partially the expression of SPARC and/or interferes with its biological function.

Garcia A.J.,National University of the South | Garcia A.J.,CONICET | Simari G.R.,National University of the South
Argument and Computation | Year: 2014

Argumentation represents a way of reasoning over a knowledge base containing possibly incomplete and/or inconsistent information, to obtain useful conclusions. As a reasoning mechanism, the way an argumentation reasoning engine reaches these conclusions resembles the cognitive process that humans follow to analyse their beliefs; thus, unlike other computationally reasoning systems, argumentation offers an intellectually friendly alternative to other defeasible reasoning systems. Logic Programming is a computational paradigm that has produced computationally attractive systems with remarkable success in many applications. Merging ideas from both areas, Defeasible Logic Programming offers a computational reasoning system that uses an argumentation engine to obtain answers from a knowledge base represented using a logic programming language extended with defeasible rules. This combination of ideas brings about a computationally effective system together with a human-like reasoning model facilitating its use in applications. © 2014 Taylor and Francis.

News Article | December 23, 2016
Site: www.eurekalert.org

The Biophysical Society has announced the winners of its annual CPOW Travel Awards to attend the Biophysical Society's 61st Annual Meeting in New Orleans, Louisiana, February 11-15, 2017. CPOW, the Society's Committee for Professional Opportunities for Women, has initiated these travel fellowships to increase the number of women biophysicists and encourage their participation at the Meeting. The recipients of this competitive award must be female postdoctoral fellows or mid-career scientists presenting a poster or oral presentation at the conference. Each awardee receives a travel grant and will be recognized at a reception on Saturday, February 11, at the Ernest N. Morial Convention Center. Teresa Aman, University of Washington, HCN CHANNEL GATING STUDIED WITH TMFRET AND A FLUORESCENT NONCANONICAL AMINO ACID. Anna Blice-Baum, Sam Houston State University, CARDIAC-SPECIFIC EXPRESSION OF VCP/TER94 RNAI OR DISEASE ALLELES DISRUPTS DROSOPHILA HEART STRUCTURE AND IMPAIRS FUNCTION. Lusine Demirkhanyan, University of Illinois at Chicago, ASSESSMENT OF ENDOGENOUS AND EXOGENOUS MODULATORS OF THE TRPM7 CHANNEL IN PLANAR LIPID BILAYERS. Maria Hoernke, Albert-Ludwigs-Universität, GUV AND LUV LEAKAGE: HOW ALL-OR-NONE AND GRADED LEAKAGE SCALE WITH VESICLE SIZE. Pooja Jadiya, Temple University, GENETIC RESCUE OF MITOCHONDRIAL CALCIUM EFFLUX IN ALZHEIMER'S DISEASE PRESERVES MITOCHONDRIAL FUNCTION AND PROTECTS AGAINST NEURONAL CELL DEATH. Marthe Ludtmann, UCL, Institute of Neurology, DIRECT MODULATION OF THE MITOCHONDRIAL PERMEABILITY TRANSITION PORE BY OLIGOMERIC ALPHA-SYNUCLEIN CAUSES TOXICITY IN PD. Yoojin Oh, Johannes Kepler University, Linz, CURLI MEDIATE BACTERIAL ADHESION TO FIBRONECTIN VIA A TENSILE COLLECTIVE BINDING NETWORK. Laura Orellana, Science for Life Laboratory, TRAPPING ON-PATHWAY INTERMEDIATES FOR LARGE SCALE CONFORMATIONAL CHANGES WITH COARSE-GRAINED SIMULATIONS. Hagit Peretz Soroka, University of Manitoba, NOVEL MECHANISM FOR DRIVING AMOEBOIDLIKE MOTILITY OF HUMAN NEUTROPHILS UNDER AN ELECTRIC FIELD, BASED ON INTRACELLULAR PROTON CURRENTS AND CYTOPLASM STREAMING. Sarah Rouse, Imperial College London, STRUCTURAL AND MECHANISTIC INSIGHTS INTO TRANSPORT OF FUNCTIONAL AMYLOID SUBUNITS ACROSS THE PSEUDOMONAS OUTER MEMBRANE. Siobhan Toal, University of Pennsylvania, DETERMINING THE ROLE OF N-TERMINAL ACETYLATION ON α-SYNUCLEIN FUNCTION. Shelli Frey, Gettysburg College, THE ROLE OF SPHINGOMYELIN AND GANGLIOSIDE GM1 IN THE INTERACTION OF POLYGLUTAMINE PEPTIDES WITH LIPID MEMBRANES. Rebecca Howard, Stockholm University, TRANSMEMBRANE STRUCTURAL DETERMINANTS OF ALCOHOL BINDING AND MODULATION IN A MODEL LIGAND-GATED ION CHANNEL. Sabina Mate, INIBIOLP-CONICET-UNLP, ORIENTATIONAL PROPERTIES OF DOPC/SM/CHOLESTEROL MIXTURES: A PM-IRRAS STUDY. Ekaterina Nestorovich, The Catholic University of America, LIPID DYNAMICS AND THE ANTHRAX TOXIN INTRACELLULAR JOURNEY. The Biophysical Society, founded in 1958, is a professional, scientific Society established to encourage development and dissemination of knowledge in biophysics. The Society promotes growth in this expanding field through its annual meeting, monthly journal, and committee and outreach activities. Its 9000 members are located throughout the U.S. and the world, where they teach and conduct research in colleges, universities, laboratories, government agencies, and industry. For more information on these awards, the Society, or the 2017 Annual Meeting, visit http://www.

Agency: European Commission | Branch: FP7 | Program: CP | Phase: ENV.2012.6.2-1 | Award Amount: 11.49M | Year: 2012

Despite improved understanding of the links between ecosystem health, provision of ecosystem services and human well-being, further conceptual and empirical work is needed to make the ideas of ecosystem services (ESS) and natural capital (NC) operational. OpenNESS will therefore develop innovative and practical ways of applying them in land, water and urban management: it will identify how, where and when the concepts can most effectively be applied to solve problems. To do this, it will work with public and private decision makers and stakeholders to better understand the range of policy and management problems faced in different case study contexts (ranging across locales, sectors, scales and time). OpenNESS will consolidate, refine and develop a range of spatially-explicit methods to identify, quantify and value ecosystem services, and will develop hybrid assessment methods. It will also explore the effectiveness of financial and governance mechanisms, such as payments for ecosystem services, habitat banking, biodiversity offsetting and land and ecosystem accounting. These types of interventions have potential for sustaining ESS and NC, and for the design of new economic and social investment opportunities. Finally, OpenNESS will assess how current regulatory frameworks and other institutional factors at EU and national levels enable or constrain consideration of ESS and NC, and identify the implications for issues related to well-being, governance and competitiveness. OpenNESS will analyse the knowledge that is needed to define ESS and NC in the legal, administrative and political contexts that are relevant to the EU. The work will deliver a menu of multi-scale solutions to be used in real life situations by stakeholders, practitioners, and decision makers in public and business organizations, by providing new frameworks, data-sets, methods and tools that are fit-for-purpose and sensitive to the plurality of decision-making contexts.

Roncaglia A.J.,FCEyN | Roncaglia A.J.,CONICET | Cerisola F.,FCEyN | Paz J.P.,FCEyN | Paz J.P.,CONICET
Physical Review Letters | Year: 2014

We present a new method to measure the work w performed on a driven quantum system and to sample its probability distribution P(w). The method is based on a simple fact that remained unnoticed until now: Work on a quantum system can be measured by performing a generalized quantum measurement at a single time. Such measurement, which technically speaking is denoted as a positive operator valued measure reduces to an ordinary projective measurement on an enlarged system. This observation not only demystifies work measurement but also suggests a new quantum algorithm to efficiently sample the distribution P(w). This can be used, in combination with fluctuation theorems, to estimate free energies of quantum states on a quantum computer. © 2014 American Physical Society.

Garcia D.,University of Oviedo | Zamora R.,University of Granada | Amico G.C.,CONICET
Conservation Biology | Year: 2010

Seed dispersal by animals is considered a pivotal ecosystem function that drives plant-community dynamics in natural habitats and vegetation recovery in human-altered landscapes. Nevertheless, there is a lack of suitable ecological knowledge to develop basic conservation and management guidelines for this ecosystem service. Essential questions, such as how well the abundance of frugivorous animals predicts seeding function in different ecosystems and how anthropogenic landscape heterogeneity conditions the role of dispersers, remain poorly answered. In three temperate ecosystems, we studied seed dispersal by frugivorous birds in landscape mosaics shaped by human disturbance. By applying a standardized design across systems, we related the frequency of occurrence of bird-dispersed seeds throughout the landscape to the abundance of birds, the habitat features, and the abundance of fleshy fruits. Abundance of frugivorous birds in itself predicted the occurrence of dispersed seeds throughout the landscape in all ecosystems studied. Even those landscape patches impoverished due to anthropogenic disturbance received some dispersed seeds when visited intensively by birds. Nonetheless, human-caused landscape degradation largely affected seed-deposition patterns by decreasing cover of woody vegetation or availability of fruit resources that attracted birds and promoted seed dispersal. The relative role of woody cover and fruit availability in seed dispersal by birds differed among ecosystems. Our results suggest that to manage seed dispersal for temperate ecosystem preservation or restoration one should consider abundance of frugivorous birds as a surrogate of landscape-scale seed dispersal and an indicator of patch quality for the dispersal function; woody cover and fruit resource availability as key landscape features that drive seedfall patterns; and birds as mobile links that connect landscape patches of different degrees of degradation and habitat quality via seed deposition. ©2010 Society for Conservation Biology.

Berli C.L.A.,CONICET | De Vicente J.,University of Granada
Applied Physics Letters | Year: 2012

A structural viscosity model is proposed, which describes the shear viscosity from the balance between build up (magnetic field-induced clustering) and breakdown (shear-induced breakup) of particle aggregates. The model accounts for typical deviations from Bingham model predictions that are extensively reported in the MR literature. More precisely, the model (i) provides a physical ground for the observed Casson-like shear flow behaviour, (ii) predicts the existence of a low shear plateau in weak MR fluids, and (iii) asymptotically recovers the typical Bingham-like behavior that is observed in (strong) conventional MR fluids at experimentally accessible times. © 2012 American Institute of Physics.

Godoy D.,UNICEN University | Godoy D.,CONICET
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) | Year: 2012

Social bookmarking systems are Web-based services that allow users to bookmark different type of resources, such as Web pages or pictures, annotate resources using keywords or tags and share their bookmarks with others. It has been argued that the main reason of the widespread success of these systems is the simplicity of organize resources using open-ended tags. The massive amount of user-generated content, however, poses the challenge for users of finding interesting resources to read as well as filtering information streams coming from social systems. The study presented in this paper aims at analyzing various types of one-class classifiers in their applicability to the problem of filtering interesting resources coming from social bookmarking systems. These algorithms were used to learn the user interests starting from different sources, such as the full-text of resources and their social tags. Experimental results using a dataset gathered from Del.icio.us collaborative system are reported, showing promising results for information filtering tasks. © 2012 Springer-Verlag.

Cassini M.H.,CONICET | Cassini M.H.,National University of Luján
Journal of Biogeography | Year: 2011

Most species distribution models (SDMs) assume that habitats are closed, stable and without competition. In that environmental context, it is ecologically correct to assume that members of a species will be distributed in direct relation to the suitability of the habitat, that is, according to the so-called habitat matching rule. This paper examines whether it is possible to maintain the assumption of the habitat matching rule in the following circumstances: (1) when habitats are connected and organisms can move between them, (2) when there are disturbances and seasonal cycles that generate instability, and (3) when there is inter-specific and intra-specific competition. Here I argue that it is possible as long as the following aspects are taken into account. In open habitats at equilibrium, in which habitat selection and competition operate, the habitat matching rule can be applied in some conditions, while competition tends to homogenize the species distribution in other environmental contexts. In the latter case, two methods can be used to incorporate these effects into SDMs: new parameters can be incorporated into the response functions, or the occurrence of proportions of categories of individuals (adult/young, male/female, or dominant/subordinate species in guilds) can be used instead of the occurrence of organisms. The habitat matching rule is not fulfilled in non-equilibrium environments. The solution to this problem lies in the design of SDMs with two strategies that depend on scale. Locally, the disequilibrium can be encapsulated using average environmental conditions, with sufficiently large cells (in the case of metapopulations) and/or long enough sampling periods (in the case of seasonal cycles). At coarse scales, the use of presence-only models can in some cases avoid the destabilizing effect of catastrophic historical processes. The matching law is a strong assumption of SDMs because it is based on population ecology theory and the principle of evolution by natural selection. © 2011 Blackwell Publishing Ltd.

Cassini M.H.,CONICET | Cassini M.H.,National University of Luján
Biodiversity and Conservation | Year: 2011

Within the Red List of the International Union for Conservation of Nature (IUCN), species distribution models (SDM) are used with two main purposes: (1) to estimate extents of occurrence as a parameter of risk of extinction and, more recently, (2) to explore potential impacts of climate change on species distribution. In this article I propose a third use of SDM: to generate objective and quantitative rankings of threats for the species categorized within the Red List. Although, some authors have published threat analyses based on SDM, most current ranking of threats conducted within IUCN Specialist Groups still relies on the subjective perspectives of workshop attendees or individual experts. I found that SDMs are ideal for incorporating theoretical and mathematical rigour to the ranking threat process, because: (1) they are of relatively easy and fast implementation, (2) they can be used with different levels of knowledge about the species in question, and (3) they are particularly suitable for use at the geographical scale for which the IUCN Red List is designed. © 2011 Springer Science+Business Media B.V.

Tissera P.B.,CONICET | Tissera P.B.,Max Planck Institute for Astrophysics | White S.D.M.,Max Planck Institute for Astrophysics | Scannapieco C.,Leibniz Institute for Astrophysics Potsdam
Monthly Notices of the Royal Astronomical Society | Year: 2012

We study the chemical properties of the stellar populations in eight simulations of the formation of Milky Way mass galaxies in a Λ cold dark matter universe. Our simulations include metal-dependent cooling and an explicitly multiphase treatment of the effects on the gas of cooling, enrichment and supernova feedback. We search for correlations between formation history and chemical abundance patterns. Differing contributions to spheroids and discs from in situ star formation and from accreted populations are reflected in differing chemical properties. Discs have younger stellar populations, with most stars forming in situ and with low α-enhancement from gas which never participated in a galactic outflow. Up to 15per cent of disc stars can come from accreted satellites. These tend to be α-enhanced, older and to have larger velocity dispersions than the in situ population. Inner spheroids have old, metal-rich and α-enhanced stars which formed primarily in situ, more than 40per cent from material recycled through earlier galactic winds. Few accreted stars are found in the inner spheroid unless a major merger occurred recently. Such stars are older, more metal-poor and more α-enhanced than the in situ population. Stellar haloes tend to have low metallicity and high α-enhancement. The outer haloes are made primarily of accreted stars. Their mean metallicity and α-enhancement reflect the masses of the disrupted satellites where they formed: more massive satellites typically have higher [Fe/H] and lower [α/Fe]. Surviving satellites have distinctive chemical patterns which reflect their extended, bursty star formation histories. These produce lower α-enhancement at given metallicity than in the main galaxy, in agreement with observed trends in the Milky Way. © 2011 The Authors Monthly Notices of the Royal Astronomical Society © 2011 RAS.

Segovia-Gutierrez J.P.,University of Granada | Berli C.L.A.,CONICET | De Vicente J.,University of Granada
Journal of Rheology | Year: 2012

The yielding behavior of conventional magnetorheological (MR) fluids is revisited for a wide range of magnetic fields and particle concentrations under a colloidal gel perspective. A two-step yielding behavior is found at intermediate magnetic fields (∼10 kA/m) that can be explained as a transition from a strong-link to a weak-link (or transition) regime upon increasing the particle concentration in the MR fluid. This two-step yielding behavior is reminiscent of the classical concepts of static (frictional) and dynamic (Bingham) yield stress. By relating macroscopic elastic properties to a scaling fractal model, we could identify the prevalent gelation regime in MR fluids. © 2012 The Society of Rheology.

Scoccola N.N.,Comision Nacional de la Energia Atomica | Scoccola N.N.,CONICET | Scoccola N.N.,Favaloro University | Riska D.O.,Finnish Society of Science and Letters | Rho M.,CEA Saclay Nuclear Research Center
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2015

Using the bound state version of the topological soliton model for the baryons we show that the existence of a bound (or quasibound) D¯-soliton state leads to the possibility of having hidden charm pentaquarks with quantum numbers and masses, which are compatible with those of the candidates recently reported by the LHCb experiment. The implications of heavy quark symmetry are elaborated. © 2015 American Physical Society. © 2015 American Physical Society.

Fernandez-Duque E.,University of Pennsylvania | Fernandez-Duque E.,CONICET
American Journal of Physical Anthropology | Year: 2011

Some monogamous primates are characterized by biparental care, territoriality, and a reduced level of physical dimorphism. In others, the relationship between those behavioral patterns and dimorphism is less clear. I tested Bergmann's and Rensch's rules using Aotus spp. body mass data and I characterized the extent of sexual dimorphism in body mass, dental and physical measurements in a socially monogamous owl monkey population (n = 91 adults) from the Argentinean Gran Chaco. A. azarai azarai from the Argentinean Chaco is larger than the more tropical owl monkey species (r = 0.7, N = 6 species), but there is no apparent increase in sexual dimorphism with increased body mass. The body masses of adult male and female A. a. azarai were remarkably similar (Mean = 1.26 kg); there were no marked sex differences in most skeletal measurements, but males had higher and wider upper and lower canines than did females. Body mass and neck circumference were positively and strongly related (r = 0.533, n = 52), and the body mass of adults was not a reliable indicator of their age (r = 0.03, n = 10). The data illustrate the complexities inherent in examining and summarizing within population variation in skeletal and nonskeletal measurements and contribute to a better understanding of the relationships between monogamous behavioral patterns and sexual dimorphism. Am J Phys Anthropol, 2011. © 2011Wiley-Liss, Inc. Copyright © 2011 Wiley-Liss, Inc.

de Vicente J.,University of Granada | Berli C.L.A.,CONICET
Rheologica Acta | Year: 2013

The yielding behavior of dilute magnetorheological (MR) fluids has been investigated using creep-recovery tests. At very low stress levels, MR fluids behave in the linear viscoelastic regime as demonstrated by the fact that the instantaneous strain equals the instantaneous (elastic) recovery. In this region, gap-spanning field-induced structures support the stress levels applied. Upon increasing the stress value, the MR fluid evolves towards a nonlinear viscoelastic response. Here, the retarded elastic and viscous strain decrease, and the plastic contribution to the instantaneous strain grows probably due to the appearance of unattached field-induced structures. A larger stress value results in a viscoplastic solid behavior with negligible retarded and viscous strain and a fully plastic instantaneous strain. Finally, a plastic fluid behavior is found when the stress value is larger than the so-called yield stress. MR fluids exhibit an intermediate behavior between non-thixotropic (simple) and highly thixotropic model yield stress fluids. © 2013 Springer-Verlag Berlin Heidelberg.

Cabello J.V.,CONICET | Lodeyro A.F.,National University of Rosario | Zurbriggen M.D.,Albert Ludwigs University of Freiburg
Current Opinion in Biotechnology | Year: 2014

Adverse environmental conditions pose serious limitations to agricultural production. Classical biotechnological approaches towards increasing abiotic stress tolerance focus on boosting plant endogenous defence mechanisms. However, overexpression of regulatory elements or effectors is usually accompanied by growth handicap and yield penalties due to crosstalk between developmental and stress-response networks. Herein we offer an overview on novel strategies with the potential to overcome these limitations based on the engineering of regulatory systems involved in the fine-tuning of the plant response to environmental hardships, including post-translational modifications, small RNAs, epigenetic control of gene expression and hormonal networks. The development and application of plant synthetic biology tools and approaches will add new functionalities and perspectives to genetic engineering programs for enhancing abiotic stress tolerance. © 2013 Elsevier Ltd.

Bond M.,CONICET | Tejedor M.F.,CONICET | Tejedor M.F.,National University of Patagonia San Juan Bosco | Campbell K.E.,Jr. | And 4 more authors.
Nature | Year: 2015

The platyrrhine primates, or New World monkeys, are immigrant mammals whose fossil record comes from Tertiary and Quaternary sediments of South America and the Caribbean Greater Antilles. The time and place of platyrrhine origins are some of the most controversial issues in primate palaeontology, although an African Palaeogene ancestry has been presumed by most primatologists. Until now, the oldest fossil records of New World monkeys have come from Salla, Bolivia, and date to approximately 26 million years ago, or the Late Oligocene epoch. Here we report the discovery of new primates from the ?Late Eocene epoch of Amazonian Peru, which extends the fossil record of primates in South America back approximately 10 million years. The new specimens are important for understanding the origin and early evolution of modern platyrrhine primates because they bear little resemblance to any extinct or living South American primate, but they do bear striking resemblances to Eocene African anthropoids, and our phylogenetic analysis suggests a relationship with African taxa. The discovery of these new primates brings the first appearance datum of caviomorph rodents and primates in South America back into close correspondence, but raises new questions about the timing and means of arrival of these two mammalian groups. ©2015 Macmillan Publishers Limited. All rights reserved.

Caggiano A.,University of Salerno | Etse G.,CONICET | Martinelli E.,University of Salerno
Computers and Structures | Year: 2012

This paper deals with simulating the mechanical response of fiber-reinforced cementitious composites (FRCCs) by means of a zero-thickness interface model formulated within the framework of discrete-crack approaches. Following a similar model already available in literature for plain concrete, the formulation of the interface element is further developed and extended to capture the key mechanical phenomena controlling the FRCC behavior. An original approach is introduced for reproducing the complex influence of fibers on the cracking phenomena of the concrete/mortar matrix. Numerical analyses demonstrate the capabilities of the proposed model and show a very good agreement with experimental results on FRCC tests. © 2012 Elsevier Ltd. All rights reserved.

LeBlanc J.G.,CONICET | Milani C.,University of Parma | de Giori G.S.,CONICET | de Giori G.S.,National University of Tucuman | And 3 more authors.
Current Opinion in Biotechnology | Year: 2013

Food-related lactic acid bacteria (LAB) as well as human gut commensals such as bifidobacteria can de novo synthesize and supply vitamins. This is important since humans lack the biosynthetic capacity for most vitamins and these must thus be provided exogenously. Although vitamins are present in a variety of foods, deficiencies still occur, mainly due to malnutrition as a result of insufficient food intake and because of poor eating habits. Fermented milks with high levels of B-group vitamins (such as folate and riboflavin) can be produced by LAB-promoted and possibly bifidobacteria-promoted biosynthesis. Moreover, certain strains of LAB produce the complex vitamin cobalamin (or vitamin B12). In this review, fermented foods with elevated levels of B-group vitamins produced by LAB used as starter cultures will be covered. In addition, genetic abilities for vitamin biosynthesis by selected human gut commensals will be discussed. © 2012 Elsevier Ltd.

Tissera P.B.,CONICET | White S.D.M.,Max Planck Institute for Astrophysics | Pedrosa S.,CONICET | Scannapieco C.,Leibniz Institute for Astrophysics Potsdam
Monthly Notices of the Royal Astronomical Society | Year: 2010

We have resimulated the six galaxy-sized haloes of the Aquarius Project including metal-dependent cooling, star formation and supernova feedback. This allows us to study not only how dark matter haloes respond to galaxy formation, but also how this response is affected by details of halo assembly history. In agreement with previous work, we find baryon condensation to lead to increased dark matter concentration. Dark matter density profiles differ substantially in shape from halo to halo when baryons are included, but in all cases the velocity dispersion decreases monotonically with radius. Some haloes show an approximately constant dark matter velocity anisotropy with β ≈ 0.1-0.2, while others retain the anisotropy structure of their baryon-free versions. Most of our haloes become approximately oblate in their inner regions, although a few retain the shape of their dissipationless counterparts. Pseudo-phase-space densities are described by a power law in radius of altered slope when baryons are included. The shape and concentration of the dark matter density profiles are not well reproduced by published adiabatic contraction models. The significant spread we find in the density and kinematic structure of our haloes appears related to differences in their formation histories. Such differences already affect the final structure in baryon-free simulations, but they are reinforced by the inclusion of baryons, and new features are produced. The details of galaxy formation need to be better understood before the inner dark matter structure of galaxies can be used to constrain cosmological models or the nature of dark matter. © 2010 The Authors. Journal compilation © 2010 RAS.

Agency: European Commission | Branch: H2020 | Program: RIA | Phase: SFS-14a-2014 | Award Amount: 5.35M | Year: 2016

The OLEUM project will generate innovative, more effective and harmonized analytical solutions to detect and fight the most common and emerging frauds and to verify the overall quality of olive oils (OOs). By a core group of 20 partners from 15 countries OLEUM will undertake RESEARCH ACTIVITIES based on the development of IMPROVED and NEW ANALYTICAL METHODS by targeted and omics approaches with the aim: i) to detect new markers of the soft deodorization process; ii) to discover illegal blends between OOs and other vegetable oils; iii) to control OO quality (e.g. freshness); iv) to improve the organoleptic assessment with a Quantitative Panel Test, based on current official methods, and supported by tailored reference materials for better calibration of the sensory panels coupled with rapid screening tools to facilitate the work of the panelists. The most promising OLEUM solutions will be subjected to VALIDATION in conformity with internationally agreed standards by peer laboratories. OLEUM will recreate a realistic deodorization scenario by producing tailored, soft deodorized OOs by lab-scale and up-scaled pilot plants to apply analytical solutions to known samples. Substantial KNOWLEDGE and TECHNOLOGY TRANSFER activities will be envisaged to aid in implementation of: a) a web-based easily-accessible, scalable and constantly updated OLEUM DATABANK, containing all the information from OLEUM research and other reliable international sources, will be available for download data and spectra and to help achieve satisfactory harmonization of analytical approaches among control laboratories; b) the OLEUM NETWORK of relevant OOs stakeholders to maximize the impact of proposed analytical solutions. Finally, a robust dissemination strategy by the OLEUM project aimed at effectively sharing results with all stakeholders in the OO supply chain has the potential to improve consumer and market confidence, and preserve the image of OOs on a global scale.

Agency: European Commission | Branch: FP7 | Program: CSA-CA | Phase: NMP-2008-2.6-3 | Award Amount: 1.14M | Year: 2009

A key thrust of FP7 is to promote international collaborative research with third countries. The EULASUR project will address the Call for Co-ordination Action in Materials by creating a cooperation platform for forming strategic research partnerships between scientists, policy makers, technology transfer and industrial experts in the EC and 3 Latin-American countries belonging to MERCOSUR: Brazil, Uruguay and Argentina (BRAU). Research topics will be identified within the fields of i) advanced functional ceramics and ii) hybrid materials and nanomaterials where significant opportunities exist for mutually beneficial actions between the two regions. The goals are designed to gain first hand knowledge of the state of the art research in these fields through summer schools, exchanges and partnership actions. The project will also address the social, political and cultural factors impacting technology transfer and collaboration between the EU and BRAU countries. The core activities of EULASUR are based on some research Groups of Excellence that already cooperate bilaterally and will integrate them with additional groups to generate a stable, integrated scientific platform of international excellence interested to collaborate in the development of materials research in specific topics of interest to both regions. The EULASUR partnership is composed of 15 research centres, 8 from Europe and 7 from BRAU countries selected on the basis of: excellence in research, complementary skills and access to national and international R&D policy makers. Government representatives will participate in the EULASUR Advisory Board. Industrial companies and technological centres are expected to take part in the project activities. EULASUR has 5 WPs. 3 designed to build contacts and identify opportunities, 1 to disseminate results to key stakeholders and policy makers and 1 management and progress measures. Each WP has two WP Leaders: one from BRAU and the other from the EU.

Thompson R.M.,University of Canberra | Thompson R.M.,Monash University | Beardall J.,Monash University | Beringer J.,Monash University | And 3 more authors.
Ecology Letters | Year: 2013

Experimental studies assessing climatic effects on ecological communities have typically applied static warming treatments. Although these studies have been informative, they have usually failed to incorporate either current or predicted future, patterns of variability. Future climates are likely to include extreme events which have greater impacts on ecological systems than changes in means alone. Here, we review the studies which have used experiments to assess impacts of temperature on marine, freshwater and terrestrial communities, and classify them into a set of 'generations' based on how they incorporate variability. The majority of studies have failed to incorporate extreme events. In terrestrial ecosystems in particular, experimental treatments have reduced temperature variability, when most climate models predict increased variability. Marine studies have tended to not concentrate on changes in variability, likely in part because the thermal mass of oceans will moderate variation. In freshwaters, climate change experiments have a much shorter history than in the other ecosystems, and have tended to take a relatively simple approach. We propose a new 'generation' of climate change experiments using down-scaled climate models which incorporate predicted changes in climatic variability, and describe a process for generating data which can be applied as experimental climate change treatments. © 2013 John Wiley & Sons Ltd/CNRS.

Villarroel-Campos D.,University of Chile | Gastaldi L.,CONICET | Conde C.,CONICET | Caceres A.,CONICET | Gonzalez-Billault C.,University of Chile
Journal of Neurochemistry | Year: 2014

Neuronal cells are characterized by the presence of two confined domains, which are different in their cellular properties, biochemical functions and molecular identity. The generation of asymmetric domains in neurons should logically require specialized membrane trafficking to both promote neurite outgrowth and differential distribution of components. Members of the Rab family of small GTPases are key regulators of membrane trafficking involved in transport, tethering and docking of vesicles through their effectors. RabGTPases activity is coupled to the activity of guanine nucleotide exchange factors or GEFs, and GTPase-activating proteins known as GAPs. Since the overall spatiotemporal distribution of GEFs, GAPs and Rabs governs trafficking through the secretory and endocytic pathways, affecting exocytosis, endocytosis and endosome recycling, it is likely that RabGTPases could have a major role in neurite outgrowth, elongation and polarization. In this review we summarize the evidence linking the functions of several RabGTPases to axonal and dendritic development in primary neurons, as well as neurite formation in neuronal cell lines. We focused on the role of RabGTPases from the trans-Golgi network, early/late and recycling endosomes, as well as the function of some Rab effectors in neuritogenesis. Finally, we also discuss the participation of the ADP-ribosylation factor 6, a member of the ArfGTPase family, in neurite formation since it seems to have an important cross-talk with RabGTPases. © 2014 International Society for Neurochemistry.

Benvenuto O.G.,National University of La Plata | Benvenuto O.G.,CONICET | De Vito M.A.,CONICET | Horvath J.E.,University of Sao Paulo
Astrophysical Journal Letters | Year: 2014

We calculate the evolution of close binary systems (CBSs) formed by a neutron star (behaving as a radio pulsar) and a normal donor star, which evolve either to a helium white dwarf (HeWD) or to ultra-short orbital period systems. We consider X-ray irradiation feedback and evaporation due to radio pulsar irradiation. We show that irradiation feedback leads to cyclic mass transfer episodes, allowing CBSs to be observed in between episodes as binary radio pulsars under conditions in which standard, non-irradiated models predict the occurrence of a low-mass X-ray binary. This behavior accounts for the existence of a family of eclipsing binary systems known as redbacks. We predict that redback companions should almost fill their Roche lobe, as observed in PSR J1723-2837. This state is also possible for systems evolving with larger orbital periods. Therefore, binary radio pulsars with companion star masses usually interpreted as larger than expected to produce HeWDs may also result in such quasi-Roche lobe overflow states, rather than hosting a carbon-oxygen WD. We found that CBSs with initial orbital periods of Pi < 1 day evolve into redbacks. Some of them produce low-mass HeWDs, and a subgroup with shorter Pi becomes black widows (BWs). Thus, BWs descend from redbacks, although not all redbacks evolve into BWs. There is mounting observational evidence favoring BW pulsars to be very massive (≳ 2 M). As they should be redback descendants, redback pulsars should also be very massive, since most of the mass is transferred before this stage. © 2014. The American Astronomical Society. All rights reserved.

Apesteguia S.,Maimónides University | Carballido J.L.,CONICET
Journal of Vertebrate Paleontology | Year: 2014

A new species of eilenodontine sphenodontian, Priosphenodon minimus, is described from a locality 400 km south of those that yield the northern Patagonian eilenodontines (the largest known terrestrial sphenodontians). The new species, represented by subadult specimens, is both the smallest known eilenodontine and the southernmost record of the group. Pr. minimus is characterized by a nearly vertical lateral process of the premaxilla; anteriorly extended frontals that lack the naso-prefrontal projections; a rounded frontal anterior process; a prefrontal that posteriorly embraces the nasal; a coronoid process of the dentary that is tall and with an anterior border that is vertical in medial view; strong anteromedial flanges on all teeth; uncommonly dense dental packing; and an anteriorly extended angular that reaches the midlength of the lower jaw. Differences from juvenile specimens of Priosphenodon avelasi, such as the interruption of the prefrontal-jugal contact, are marked. The holotype and associated material come from early Albian strata, and are therefore around 12 million years older than the northern Patagonian giant sphenodontians. The new species here described reveals that many of the characters used to diagnose Kaikaifilusaurus calvoi are widespread, so this taxon should be regarded as a nomen dubium. Therefore, the genus Priosphenodon is considered as valid herein, with the new species assigned to it. A phylogenetic analysis demonstrates the monophyly of Priosphenodon and suggests that the new taxon represents an incidence of dwarfing. This discovery increases the morphological disparity among these specialized herbivores, and provides new climatological and biostratigraphic information on the terrestrial ecosystems of Patagonia. © 2014 Copyright Taylor & Francis Group, LLC.

Provasi P.F.,University of Northeastern | Provasi P.F.,CONICET | Sauer S.P.A.,Copenhagen University
Journal of Chemical Physics | Year: 2010

The aug-cc-pVTZ-J series of basis sets for indirect nuclear spin-spin coupling constants has been extended to the atoms B, Al, Si, P, and Cl. The basis sets were obtained according to the scheme previously described by Provasi [J. Chem. Phys. 115, 1324 (2001)]. First, the completely uncontracted correlation consistent aug-cc-pVTZ basis sets were extended with four tight s and three tight d functions. Second, the s and p basis functions were contracted with the molecular orbital coefficients of self-consistent-field calculations performed with the uncontracted basis sets on the simplest hydrides of each atom. As a first illustration, we have calculated the one-bond indirect spin-spin coupling constants in BH4 -, BF, AlH, AlF, SiH4, SiF4, PH3, PF3, H2 S, SF6, HCl, and ClF at the level of density functional theory using the Becke three parameter Lee-Yang-Parr and the second order polarization propagator approximation with coupled cluster singles and doubles amplitudes. © 2010 American Institute of Physics.

Kitazawa H.,Tohoku University | Villena J.,Immunobiotics Research Group | Villena J.,CONICET
Frontiers in Immunology | Year: 2014

Respiratory syncytial virus (RSV) is the leading cause of lower respiratory tract illness in infants and young children. Host immune response is implicated in both protective and immunopathological mechanisms during RSV infection. Activation of Toll-like receptor (TLR)-3 in innate immune cells by RSV can induce airway inflammation, protective immune response, and pulmonary immunopathology. A clear understanding of RSV-host interaction is important for the development of novel and effective therapeutic strategies. Several studies have centered on whether probiotic microorganisms with the capacity to stimulate the immune system (immunobiotics) might sufficiently stimulate the common mucosal immune system to improve defenses in the respiratory tract. In this regard, it was demonstrated that some orally administered immunobiotics do have the ability to stimulate respiratory immunity and increase resistance to viral infections. Moreover, during the last decade scientists have significantly advanced in the knowledge of the cellular and molecular mechanisms involved in the protective effect of immunobiotics in the respiratory tract. This review examines the most recent advances dealing with the use of immunobiotic bacteria to improve resistance against viral respiratory infections. More specifically, the article discuss the mechanisms involved in the capacity of the immunobiotic strain Lactobacillus rhamnosus CRL1505 to modulate the TLR3-mediated immune response in the respiratory tract and to increase the resistance to RSV infection. In addition, we review the role of interferon (IFN)-γ and interleukin (IL)-10 in the immunoregulatory effect of the CRL1505 strain that has been successfully used for reducing incidence and morbidity of viral airways infections in children. © 2014 Kitazawa and Villena.

Abbas T.,University of Virginia | Mueller A.C.,University of Virginia | Shibata E.,University of Virginia | Keaton M.,University of Virginia | And 3 more authors.
Molecular Cell | Year: 2013

The Cul4-Cdt2 (CRL4Cdt2) E3 ubiquitin ligase is a master regulator of cell-cycle progression and genome stability. Despite its central role in the degradation of many cell-cycle regulators, e.g., Cdt1, p21, and Pr-Set7/Set8, little is known about the regulation of its activity. We report that Cdt2 is autoubiquitylated by the CRL4A E3 ubiquitin ligase. Cdt2 is additionally polyubiquitylated and degraded by Cul1-FBXO11 (CRL1FBXO11). CRL1FBXO11-mediated degradation of Cdt2 stabilizes p21 and Set8, and this is important during the response to TGF-β, with the Set8 induction being important for turning off the activation of Smad2. The migration of epithelial cells is also stimulated by CRL1FBXO11-mediated downregulation of Cdt2 and the consequent stabilization of Set8. This is an interesting example of crossregulation between specific Cullin 4 and Cullin 1 E3 ubiquitin ligases and highlights the role of ubiquitylation in regulating cellular responses to TGF-β and the migration of epithelial cells. © 2013 Elsevier Inc.

Castano Rivera P.,Institute Tecnologia Jorge Sabato | Ramunni V.P.,CONICET | Bruzzoni P.,Comision Nacional de la Energia Atomica
Corrosion Science | Year: 2012

Electrochemical hydrogen permeation tests were performed on an API 5L X60 steel to study trapping and diffusion properties in the as-received (AR) and in a cold-rolled (CR) state, at 30, 50 and 70°C. Hydrogen trapping was characterized by assuming saturable traps in local equilibrium. Binding energies (ΔG) and trap densities (N) were determined by fitting a trapping theoretical model to experimental data. Both conditions AR and CR present a high density of weak traps |ΔG|<35kJ/mol, namely N=1.4×10-5 and 7.9×10-4mol/cm3 respectively. Strong trapping sites were detected (-72<ΔG<-57kJ/mol) and their densities increased markedly after cold-rolling. © 2011 Elsevier Ltd.

Ferreiro D.U.,CONICET | Komives E.A.,University of California at San Diego | Wolynes P.G.,Rice University
Quarterly Reviews of Biophysics | Year: 2014

Biomolecules are the prime information processing elements of living matter. Most of these inanimate systems are polymers that compute their own structures and dynamics using as input seemingly random character strings of their sequence, following which they coalesce and perform integrated cellular functions. In large computational systems with finite interaction-codes, the appearance of conflicting goals is inevitable. Simple conflicting forces can lead to quite complex structures and behaviors, leading to the concept of frustration in condensed matter. We present here some basic ideas about frustration in biomolecules and how the frustration concept leads to a better appreciation of many aspects of the architecture of biomolecules, and especially how biomolecular structure connects to function by means of localized frustration. These ideas are simultaneously both seductively simple and perilously subtle to grasp completely. The energy landscape theory of protein folding provides a framework for quantifying frustration in large systems and has been implemented at many levels of description. We first review the notion of frustration from the areas of abstract logic and its uses in simple condensed matter systems. We discuss then how the frustration concept applies specifically to heteropolymers, testing folding landscape theory in computer simulations of protein models and in experimentally accessible systems. Studying the aspects of frustration averaged over many proteins provides ways to infer energy functions useful for reliable structure prediction. We discuss how frustration affects folding mechanisms. We review here how the biological functions of proteins are related to subtle local physical frustration effects and how frustration influences the appearance of metastable states, the nature of binding processes, catalysis and allosteric transitions. In this review, we also emphasize that frustration, far from being always a bad thing, is an essential feature of biomolecules that allows dynamics to be harnessed for function. In this way, we hope to illustrate how Frustration is a fundamental concept in molecular biology. © Cambridge University Press 2014.

Gundel P.E.,CONICET | Rudgers J.A.,Rice University | Ghersa C.M.,CONICET
Oikos | Year: 2011

Variation exists in the frequency of obligate, vertically transmitted symbiotic organisms within and among host populations; however, these patterns have not been adequately explained by variable fitness effects of symbionts on their hosts. In this forum, we call attention to another equally important, but overlooked mechanism to maintain variation in the frequency of symbioses in nature: the rate of vertical transmission. On ecological time scales, vertical transmission can affect the equilibrium frequencies of symbionts in host populations, with potential consequences for population and community dynamics. In addition, vertical transmission has the potential to influence the evolution of symbiosis, by affecting the probability of fixation of symbiosis (and therefore the evolution of complexity) and by allowing hosts to sanction against costly symbionts. Here we use grass-epichloae symbioses as a model system to explore the causes and consequences of variation in vertical transmission rates. We identify critical points for symbiont transmission that emerge from considering the host growth cycle devoted to reproduction (asexual vs sexual) and the host capability to maintain homeostasis. We also use information on the process of transmission to predict the environmental factors that would most likely affect transmission rates. Altogether, we aim to highlight the vertical transmission rate as an important process for understanding the ecology and evolution of symbiosis, using grass-epichloae interactions as a case study. © 2011 The Authors. Oikos © 2011 Nordic Society Oikos.

Osman K.T.,University of Delaware | Wan M.,University of Delaware | Matthaeus W.H.,University of Delaware | Weygand J.M.,University of California at Los Angeles | Dasso S.,CONICET
Physical Review Letters | Year: 2011

The first direct determination of the inertial range energy cascade rate, using an anisotropic form of Yaglom's law for magnetohydrodynamic turbulence, is obtained in the solar wind with multispacecraft measurements. The two-point mixed third-order structure functions of Elsässer fluctuations are integrated over a sphere in magnetic field-aligned coordinates, and the result is consistent with a linear scaling. Therefore, volume integrated heating and cascade rates are obtained that, unlike previous studies, make only limited assumptions about the underlying spectral geometry of solar wind turbulence. These results confirm the turbulent nature of magnetic and velocity field fluctuations in the low frequency limit, and could supply the energy necessary to account for the nonadiabatic heating of the solar wind. © 2011 American Physical Society.

Haimovici A.,University of Buenos Aires | Haimovici A.,CONICET | Tagliazucchi E.,Goethe University Frankfurt | Balenzuela P.,University of Buenos Aires | And 4 more authors.
Physical Review Letters | Year: 2013

The relation between large-scale brain structure and function is an outstanding open problem in neuroscience. We approach this problem by studying the dynamical regime under which realistic spatiotemporal patterns of brain activity emerge from the empirically derived network of human brain neuroanatomical connections. The results show that critical dynamics unfolding on the structural connectivity of the human brain allow the recovery of many key experimental findings obtained from functional magnetic resonance imaging, such as divergence of the correlation length, the anomalous scaling of correlation fluctuations, and the emergence of large-scale resting state networks. © 2013 American Physical Society.

Bauer E.,National University of La Plata | Bauer E.,CONICET | Garbarino G.,University of Turin
Physical Review C - Nuclear Physics | Year: 2010

The contribution of ground-state correlations (GSCs) to the nonmesonic weak decay of Λ12C and other medium to heavy hypernuclei is studied within a nuclear-matter formalism implemented in a local-density approximation. We adopt a weak transition potential including the exchange of the complete octets of pseudoscalar and vector mesons, as well as a residual strong interaction modeled on the Bonn potential. Leading GSC contributions, at first order in the residual strong interaction, are introduced on the same footing for all isospin channels of one- and two-nucleon induced decays. Together with fermion antisymmetrization, GSCs turn out to be important for an accurate determination of the decay widths. Besides opening the two-nucleon stimulated decay channels, for Λ12C GSCs are responsible for 14% of the rate Γ1 while increasing the Γn/Γp ratio by 4%. Our final results for Λ12C are ΓNM=0.98, Γn/Γp=0.34, and Γ2/ΓNM=0.26. The saturation property of ΓNM with increasing hypernuclear mass number is clearly observed. The agreement with data of our predictions for ΓNM, Γn/Γp, and Γ2 is rather good. © 2010 The American Physical Society.

Rivas A.M.F.,Comision Nacional de la Energia Atomica | Rivas A.M.F.,CONICET
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2013

In this work, we derived a semiclassical approximation for the matrix elements of a quantum propagator in coherent states (CS) basis that avoids complex trajectories; it only involves real ones. For that purpose, we used the symplectically invariant semiclassical Weyl propagator obtained by performing a stationary phase approximation (SPA) for the path integral in the Weyl representation. After that, for the transformation to CS representation SPA is avoided; instead a quadratic expansion of the complex exponent is used. This procedure also allows us to express the semiclassical CS propagator uniquely in terms of the classical evolution of the initial point without the need of any root search typical of van Vleck-Gutzwiller-based propagators. For the case of chaotic Hamiltonian systems, the explicit time dependence of the CS propagator has been obtained. The comparison with a realistic chaotic system that derives from a quadratic Hamiltonian, the cat map, reveals that the expression here derived is exact up to quadratic Hamiltonian systems. © 2013 American Physical Society.

Bejas M.,Abdus Salam International Center For Theoretical Physics | Greco A.,CONICET | Yamase H.,Japan National Institute of Materials Science | Yamase H.,Max Planck Institute for Solid State Research
Physical Review B - Condensed Matter and Materials Physics | Year: 2012

Motivated by the growing evidence of the importance of charge fluctuations in the pseudogap phase in high-temperature cuprate superconductors, we apply a large-N expansion formulated in a path integral representation of the two-dimensional t-J model on a square lattice. We study all possible charge instabilities of the paramagnetic state in leading order of the 1/N expansion. While the d-wave charge density wave (flux phase) becomes the leading instability for various choices of model parameters, we find that a d-wave Pomeranchuk (electronic nematic phase) instability occurs as a next leading one. In particular, the nematic state has a strong tendency to become inhomogeneous. In the presence of a large second nearest-neighbor hopping integral, the flux phase is suppressed and the electronic nematic instability becomes leading in a high doping region. Besides these two major instabilities, bond-order phases occur as weaker instabilities close to half-filling. Phase separation is also detected in a finite temperature region near half-filling. © 2012 American Physical Society.

Gao K.,Xiamen University | Helbling E.W.,CONICET | Hader D.-P.,Neue Str. 9 | Hutchins D.A.,University of Southern California
Marine Ecology Progress Series | Year: 2012

Anthropogenic CO2 is accumulating in the atmosphere and trapping reflected infrared radiation, resulting in warming of both terrestrial and ocean ecosystems. At the same time, the dissolution of CO2 into seawater is increasing surface ocean acidity, a process known as ocean acidification. Effects of ocean acidification on marine primary producers have been documented to be stimulative, inhibitive, or neutral. Elevated CO 2 and reduced pH levels can interact with solar radiation, which fluctuates over different time scales from limiting to saturating or even stressful levels, to bring about synergistic, antagonistic, or balanced effects on marine primary producers at different depths or under changing weather conditions. However, shoaling of the upper mixed layer (enhanced stratification) due to ocean warming and freshening (rain, ice melting) can lead to additional photosynthetically active radiation (PAR) and ultraviolet (UV) exposure, which can have both benefits and costs to photosynthetic organisms. Elevated CO 2 concentrations under low or moderate levels of PAR have been shown to enhance photosynthesis or growth of both phytoplankton and macroalgae; excessive levels of PAR, however, can lead to additional inhibition of photosynthesis or growth under elevated CO2, and addition of UV radiation (280 to 400 nm) can increase or down-regulate such inhibition, since solar UV-B (280 to 315 nm) radiation often harms algal cells, while UV-A (315 to 400 nm) at moderate levels stimulates photosynthetic carbon fixation in both phytoplankton and macroalgae. In view of warming effects, increased temperatures have been shown to enhance photorepair of UV-damaged molecules, though it simultaneously enhances respiratory carbon loss. The net effects of ocean acidification on marine primary producers are therefore largely dependent on the photobiological conditions (light limitation, light or UV stress), as well as interactions with rising temperature and other variables such as altered nutrient availability. Hence, feedbacks between changing carbonate chemistry and solar radiation across the entire spectrum present complications to interpret and understand ocean acidification effects based on single-factor experiments. © Inter-Research 2012.

Prevosti F.J.,Museo Argentino de Ciencias Naturales Bernardino Rivadavia | Chemisquy M.A.,CONICET
Cladistics | Year: 2010

Here we explore the effect of missing data in phylogenetic analyses using a large number of real morphological matrices. Different percentages and patterns of missing entries were added to each matrix, and their influence was evaluated by comparing the accuracy and error of most parsimonious trees. The relationships between accuracy and error and different parameters (e.g. the number of taxa and characters, homoplasy, support) were also evaluated. Our findings, based on real matrices, agree with the simulation studies, i.e. the negative effect increases with the percentage of missing entries, and decreases with the addition of more characters. This indicates that the main problem is the lack of information, not just the presence of missing data per se. Accuracy varies with different distribution patterns of missing entries; the worst case is when missing data are concentrated in a few taxa, while the best is when the missing entries are restricted to just a few characters. The results expand our knowledge of the missing data problem, corroborate many of the findings previously published using simulations, and could be useful for empirical or theoretical studies. © The Willi Hennig Society 2009.

Tian F.,CAS National Astronomical Observatories | Tian F.,Tsinghua University | France K.,University of Colorado at Boulder | Linsky J.L.,University of Colorado at Boulder | And 2 more authors.
Earth and Planetary Science Letters | Year: 2014

Recent observations of several planet-hosting M dwarfs show that most have FUV/NUV flux ratios 1000 times greater than that of the Sun. Here we show that the atmospheric oxygen contents (O2 and O3) of potentially habitable planets in this type of UV environment could be 2-3 orders of magnitude greater than those of their counterparts around Sun-like stars as a result of decreased photolysis of O3, H2O2, and HO2. Thus detectable levels of atmospheric oxygen, in combination with the existence of H2O and CO2, may not be the most promising biosignatures on planets around stars with high FUV/NUV ratios such as the observed M dwarfs. © 2013 Elsevier B.V.

Langer M.C.,University of Sao Paulo | Ezcurra M.D.,Museo Argentino de Ciencias Naturales Bernardino Rivadavia | Bittencourt J.S.,University of Sao Paulo | Novas F.E.,Museo Argentino de Ciencias Naturales Bernardino Rivadavia | Novas F.E.,CONICET
Biological Reviews | Year: 2010

The oldest unequivocal records of Dinosauria were unearthed from Late Triassic rocks (approximately 230 Ma) accumulated over extensional rift basins in southwestern Pangea. The better known of these are Herrerasaurus ischigualastensis, Pisanosaurus mertii, Eoraptor lunensis, and Panphagia protos from the Ischigualasto Formation, Argentina, and Staurikosaurus pricei and Saturnalia tupiniquim from the Santa Maria Formation, Brazil. No uncontroversial dinosaur body fossils are known from older strata, but the Middle Triassic origin of the lineage may be inferred from both the footprint record and its sister-group relation to Ladinian basal dinosauromorphs. These include the typical Marasuchus lilloensis, more basal forms such as Lagerpeton and Dromomeron, as well as silesaurids: a possibly monophyletic group composed of Mid-Late Triassic forms that may represent immediate sister taxa to dinosaurs. The first phylogenetic definition to fit the current understanding of Dinosauria as a node-based taxon solely composed of mutually exclusive Saurischia and Ornithischia was given as "all descendants of the most recent common ancestor of birds and Triceratops". Recent cladistic analyses of early dinosaurs agree that Pisanosaurus mertii is a basal ornithischian; that Herrerasaurus ischigualastensis and Staurikosaurus pricei belong in a monophyletic Herrerasauridae; that herrerasaurids, Eoraptor lunensis, and Guaibasaurus candelariensis are saurischians; that Saurischia includes two main groups, Sauropodomorpha and Theropoda; and that Saturnalia tupiniquim is a basal member of the sauropodomorph lineage. On the contrary, several aspects of basal dinosaur phylogeny remain controversial, including the position of herrerasaurids, E. lunensis, and G. candelariensis as basal theropods or basal saurischians, and the affinity and/or validity of more fragmentary taxa such as Agnosphitys cromhallensis, Alwalkeria maleriensis, Chindesaurus bryansmalli, Saltopus elginensis, and Spondylosoma absconditum. The identification of dinosaur apomorphies is jeopardized by the incompleteness of skeletal remains attributed to most basal dinosauromorphs, the skulls and forelimbs of which are particularly poorly known. Nonetheless, Dinosauria can be diagnosed by a suite of derived traits, most of which are related to the anatomy of the pelvic girdle and limb. Some of these are connected to the acquisition of a fully erect bipedal gait, which has been traditionally suggested to represent a key adaptation that allowed, or even promoted, dinosaur radiation during Late Triassic times. Yet, contrary to the classical "competitive" models, dinosaurs did not gradually replace other terrestrial tetrapods over the Late Triassic. In fact, the radiation of the group comprises at least three landmark moments, separated by controversial (Carnian-Norian, Triassic-Jurassic) extinction events. These are mainly characterized by early diversification in Carnian times, a Norian increase in diversity and (especially) abundance, and the occupation of new niches from the Early Jurassic onwards. Dinosaurs arose from fully bipedal ancestors, the diet of which may have been carnivorous or omnivorous. Whereas the oldest dinosaurs were geographically restricted to south Pangea, including rare ornithischians and more abundant basal members of the saurischian lineage, the group achieved a nearly global distribution by the latest Triassic, especially with the radiation of saurischian groups such as "prosauropods" and coelophysoids. © 2009 Cambridge Philosophical Society.

Prevosti F.J.,Museo Argentino de Ciencias Naturales Bernardino Rivadavia | Forasiepi A.,CONICET | Zimicz N.,CONICET
Journal of Mammalian Evolution | Year: 2013

South America was isolated from other continents during most of the Cenozoic, developing a singular mammalian fauna. In contrast to North America, Europe, Asia, and Africa, up to the late Neogene, the carnivore adaptive zone in South America was populated by crocodiles (Sebecidae), large snakes (Madtsoiidae), large birds (Phorusrhacidae), and metatherian mammals (Sparassodonta). Sparassodonta were varied and comprised a wide range of body masses (≈ 2-50 kg) and food habits. Their diversity decreased towards the late Miocene (Huayquerian Stage/Age) and the group became extinct in the "middle" Pliocene (≈ 3 Ma, Chapadmalalan Stage/Age). Several authors have suggested that the cause of this decline and extinction was the ingression of carnivorans to South America (about 6-7 Ma ago), because they competed with the Sparassodonta; although this hypothesis has been criticized in recent years. With the intention of testing the hypothesis of "competitive displacement," we review the fossil record of South American Sparassodonta and Carnivora, collect data about diversity, estimate size and diet, and determine first and last appearances. The diversity of Sparassodonta is low relative to that of Carnivora throughout the Cenozoic with the early Miocene (Santacrucian Stage/Age) showing the greatest diversity with 11 species. In the late Miocene-middle Pliocene (Huayquerian Stage/Age), the fossil record shows overlap of groups, and the Sparassodonta's richness curve begins to decline with the first record of Carnivora. Despite this overlap, carnivorans diversity ranged from four or fewer species in the late Miocene-Pliocene to a peak of around 20 species in the early Pleistocene (Ensenadan Stage/Age). Carnivora was initially represented by small-sized, omnivorous species, with large omnivores first appearing in the Chapadmalalan Stage/Age. Over this period, Sparassodonta was represented by large and small hypercarnivores and a single large omnivorous species. From this review of the fossil record, it is suggested that factors other than competitive displacement may have caused the extinction of the Sparassodonta. © 2011 Springer Science+Business Media, LLC.

The only species of previously named Myrsidea Waterston, 1915 from Neotropical jays of the genus Cyanocorax Boie (Passeriformes: Corvidae), Myrsidea fallax Kéler, 1938 (type-host Cyanocorax cyanomelas Vieillot), is redescribed and six new species of lice in the genus Myrsidea are described: Myrsideapseudofallax n. sp. [type-host C. c. chrysops (Vieillot)]; M. moriona n. sp. [type-host C. m. morio (Wagler)]; Myrsidea daleclaytoni n. sp. [type-host C. v. violaceus Du Bus de Gisignies]; Myrsidealindolphoi n. sp. [type-host C. caeruleus (Vieillot)]; Myrsideamelanocyanei n. sp. [type-host C. melanocyaneus chavezi (Miller & Griscom)]; and Myrsideacristatelli n. sp. [type-host C. cristatellus (Temminck)]. A key to the identification of both sexes of these seven species is provided. Immature stages of M. daleclaytoni n. sp. (all instars) and M. cristatelli n. sp. (nymph III) are described. External chorionic architecture of the eggs is described and illustrated for six Myrsidea spp. from corvine birds: M. picae (Linnaeus, 1758) ex Pica p. pica L.; M. cornicis (DeGeer, 1778) ex Corvus c. corone L.; M. isostoma (Nitzsch in Giebel, 1866) ex Co. f. frugilegus L.; M. interrupta (Osborn, 1896) ex Co. brachyrhynchus Brehm; M. fallax ex Cy. cyanomelas; and M. moriona n. sp. ex Cy. m. morio. This is the first review of the data on Myrsidea spp. infesting Neotropical Corvidae. © 2015, Springer Science+Business Media Dordrecht.

Andreani R.,University of Campinas | Haeser G.,Federal University of São Paulo | Schuverdt M.L.,CONICET | Silva P.J.S.,University of Sao Paulo
Mathematical Programming | Year: 2012

In this work we introduce a relaxed version of the constant positive linear dependence constraint qualification (CPLD) that we call RCPLD. This development is inspired by a recent generalization of the constant rank constraint qualification by Minchenko and Stakhovski that was called RCRCQ. We show that RCPLD is enough to ensure the convergence of an augmented Lagrangian algorithm and that it asserts the validity of an error bound. We also provide proofs and counter-examples that show the relations of RCRCQ and RCPLD with other known constraint qualifications. In particular, RCPLD is strictly weaker than CPLD and RCRCQ, while still stronger than Abadie's constraint qualification. We also verify that the second order necessary optimality condition holds under RCRCQ. © 2011 Springer and Mathematical Optimization Society.

Huespe A.E.,CONICET | Needleman A.,University of North Texas | Oliver J.,University of Barcelona | Sanchez P.J.,CONICET
International Journal of Plasticity | Year: 2012

We present a finite deformation generalization of the finite thickness embedded discontinuity formulation presented in our previous paper [A.E. Huespe, A. Needleman, J. Oliver, P.J. Sánchez, A finite thickness band method for ductile fracture analysis, Int. J. Plasticity 25 (2009) 2349-2365]. In this framework the transition from a weak discontinuity to a strong discontinuity can occur using a single constitutive relation which is of importance in a range of applications, in particular ductile fracture, where localization typically precedes the creation of new free surface. An embedded weak discontinuity is introduced when the loss of ellipticity condition is met. The resulting localized deformation band is given a specified thickness which introduces a length scale thus providing a regularization of the post-localization response. The methodology is illustrated through several example problems emphasizing finite deformation effects including the development of a cup-cone failure in round bar tension. © 2011 Elsevier Ltd. All rights reserved.

Urrutia I.,Comision Nacional de la Energia Atomica | Urrutia I.,CONICET
Physical Review E - Statistical, Nonlinear, and Soft Matter Physics | Year: 2014

In this work I derive analytic expressions for the curvature-dependent fluid-substrate surface tension of a hard-sphere fluid on a hard curved wall. In the first step, the curvature thermodynamic properties are found as truncated power series in the activity in terms of the exactly known second- and third-order cluster integrals of the hard-sphere fluid near spherical and cylindrical walls. These results are then expressed as packing fraction power series and transformed to different reference regions, which is equivalent to considering different positions of the dividing surface. Based on the truncated series it is shown that the bending rigidity of the system is non-null and that higher-order terms in the curvature also exist. In the second step, approximate analytic expressions for the surface tension, the Tolman length, the bending rigidity, and the Gaussian rigidity as functions of the packing fraction are found by considering the known terms of the series expansion complemented with a simple fitting approach. It is found that the obtained formulas accurately describe the curvature thermodynamic properties of the system; further, they are more accurate than any previously published expressions. © 2014 American Physical Society.

Sangeeta Devi Y.,Michigan State University | Halperin J.,Maimónides University | Halperin J.,CONICET
Molecular and Cellular Endocrinology | Year: 2014

Prolactin (PRL) is a polypeptide hormone with a wide range of physiological functions, and is critical for female reproduction. PRL exerts its action by binding to membrane bound receptor isoforms broadly classified as the long form and the short form receptors. Both receptor isoforms are highly expressed in the ovary as well as in the uterus. Although signaling through the long form is believed to be more predominant, it remains unclear whether activation of this isoform alone is sufficient to support reproductive functions or whether both types of receptor are required. The generation of transgenic mice selectively expressing either the short or the long form of PRL receptor has provided insight into the differential signaling mechanisms and physiological functions of these receptors. This review describes the essential finding that both long and short receptor isoforms are crucial for ovarian functions and female fertility, and highlights novel mechanisms of action for these receptors. © 2013 Elsevier Ireland Ltd.

Paz D.J.,CONICET | Sgro M.A.,CONICET | Merchan M.,CONICET | Padilla N.,University of Chile
Monthly Notices of the Royal Astronomical Society | Year: 2011

In this paper we analyse the alignment of galaxy groups with the surrounding large scale structure traced by spectroscopic galaxies from the Sloan Digital Sky Survey Data Release 7. We characterize these alignments by means of an extension of the classical two-point cross-correlation function, developed by Paz et al. We find a strong alignment signal between the projected major axis of group shapes and the surrounding galaxy distribution up to scales of 30Mpch-1. This observed anisotropy signal becomes larger as the galaxy group mass increases, in excellent agreement with the corresponding predicted alignment obtained from mock catalogues and ΛCDM cosmological simulations. These measurements provide new direct evidence of the adequacy of the gravitational instability picture to describe the large-scale structure formation of our Universe. © 2011 The Authors Monthly Notices of the Royal Astronomical Society © 2011 RAS.

Bouzat S.,CONICET | Falo F.,University of Zaragoza
Physical Biology | Year: 2011

We analyze theoretically the problem of cargo transport along microtubules by motors of two species with opposite polarities. We consider two different one-dimensional models previously developed in the literature: a quite widespread model which assumes equal force sharing, here referred to as the mean field model (MFM), and a stochastic model (SM) which considers individual motor-cargo links. We find that in generic situations, the MFM predicts larger cargo mean velocity, smaller mean run time and less frequent reversions than the SM. These phenomena are found to be the consequences of the load sharing assumptions and can be interpreted in terms of the probabilities of the different motility states. We also explore the influence of the viscosity in both models and the role of the stiffness of the motor-cargo links within the SM. Our results show that the mean cargo velocity is independent of the stiffness, while the mean run time decreases with such a parameter. We explore the case of symmetric forward and backward motors considering kinesin-1 parameters, and the problem of transport by kinesin-1 and cytoplasmic dyneins considering two different sets of parameters previously proposed for dyneins. © 2011 IOP Publishing Ltd.

Agency: European Commission | Branch: FP7 | Program: BSG-CSO | Phase: ENV.2011.4.2.3-1 | Award Amount: 2.47M | Year: 2012

Current development models are leading to unprecedented environmental challenges, chief amongst them, climate change. How to respond to these challenges are key research questions. Although they are global problems, their effects are felt locally, especially by the communities that traditionally base their livelihoods in those natural resources. The relevance of these problems at global level has driven different initiatives to increase public awareness and to put in practice measures to improve them. However, many good conservation and management practices are done at local level. Research is needed to better understand local capabilities and to encourage and support potential locally-owned solutions. COMET-LAs objective is to identify sustainable community-based governance models for the management of natural resources that could be used in different social-ecological systems in a context of climate change and increasing competition for the use of these resources. A civil society-scientific partnership has been created to develop the project. Three Latin American civil society organizations, a global CSO and 7 research institutions (3 Latin American and 4 European) comprise this partnership. COMET-LA will create a space of interaction for CSOs, policy makers and research organizations, sharing local and scientific knowledge and contributing to a better knowledge of problems and potential solutions for current and future sustainable management of natural resources. Three different case studies will be analyzed: water and biodiversity systems in Colombia, forest systems in Mexico and marine and coastal areas in Argentina. Similar methods will be used to characterize the current and future ecosystem states, sustainable governance models and locally-tailored scenarios for future changes and challenges. The outcomes will be synthesized and up-scaled to deliver a potentially useful tool to other local communities facing current environmental challenges.

Conicet, University of Buenos Aires, Comision Nacional de la Energia Atomica and Ypf Tecnologia S.A. | Date: 2015-12-23

A nanoporous material made of aggregated polymeric nanoparticles wherein at least 40% of the nanoparticles have a diameter above 50 nm, and a process for producing thereof. Also, a nanoporous material membrane, a process for its manufacturing, and to a method using said membrane for separating hydrophobic compounds from its mixtures in water

Conicet and Comision Nacional de la Energia Atomica | Date: 2011-06-22

A method of quantization of magnetic nanoparticle absorption in animal tissues includes determination of the number of magnetic nanoparticles absorbed in animal tissues by magnetization measurements. The method is based on the measurement of magnetization versus magnetic field applied of the tissue sample absorbed with the nanoparticles obtaining their saturation magnetization. This magnitude is compared to the saturation magnetization of the same nanoparticles found in the tissue for the determination of the absolute number of magnetic nanoparticles in the animal tissue studied. The method includes preparing the samples for the sample holder, measuring the magnetization vs. applied magnetic field of a known number of magnetic nanoparticles, determining the saturation magnetization of the sample to be studied by measuring the magnetization and calculating the nanoparticle mass in the tissues from the data measured (saturation magnetization of the sample and of calibration of nanoparticles).

Finlayson S.A.,Texas AgriLife Research Center | Krishnareddy S.R.,Texas AgriLife Research Center | Kebrom T.H.,Texas AgriLife Research Center | Casal J.J.,CONICET
Plant Physiology | Year: 2010

The red light:far-red light ratio perceived by phytochromes controls plastic traits of plant architecture, including branching. Despite the significance of branching for plant fitness and productivity, there is little quantitative and mechanistic information concerning phytochrome control of branching responses in Arabidopsis (Arabidopsis thaliana). Here, we show that in Arabidopsis, the negative effects of the phytochrome B mutation and of low red light:far-red light ratio on branching were largely due to reduced bud outgrowth capacity and an increased degree of correlative inhibition acting on the buds rather than due to a reduced number of leaves and buds available for branching. Phytochrome effects on the degree of correlative inhibition required functional BRANCHED1 (BRC1), BRC2, AXR1, MORE AXILLARY GROWTH2 (MAX2), and MAX4. The analysis of gene expression in selected buds indicated that BRC1 and BRC2 are part of different gene networks. The BRC1 network is linked to the growth capacity of specific buds, while the BRC2 network is associated with coordination of growth among branches. We conclude that the branching integrators BRC1 and BRC2 are necessary for responses to phytochrome, but they contribute differentially to these responses, likely acting through divergent pathways. © 2010 American Society of Plant Biologists.

Foa Torres L.E.F.,National University of Cordoba | Perez-Piskunow P.M.,National University of Cordoba | Balseiro C.A.,Bariloche Atomic Center | Balseiro C.A.,CONICET | And 2 more authors.
Physical Review Letters | Year: 2014

We report on simulations of the dc conductance and quantum Hall response of a Floquet topological insulator using Floquet scattering theory. Our results reveal that laser-induced edge states lead to quantum Hall plateaus once imperfect matching with the nonilluminated leads is lessened. The magnitude of the Hall plateaus, however, is not directly related to the number and chirality of all the edge states at a given energy, as usual. Instead, the plateaus are dominated by those edge states adding to the time-averaged density of states. Therefore, the dc quantum Hall conductance of a Floquet topological insulator is not directly linked to topological invariants of the full Floquet bands. © 2014 American Physical Society.

Moreno M.F.,Bariloche Atomic Center | Gonzalez Oliver C.J.R.,CONICET
Powder Technology | Year: 2011

Pure Al, Alumix 13 (Al-4.5. wt.% Cu 0.5. Mg 0.2 Si) powders and Alumix13 reinforced with 15. wt.% Saffil short fibers were compacted up to 250-386. MPa in an axial die to study their compacting behavior. The final relative densities D were higher than 0.95 for all unreinforced powders and 0.86 for the composite. Different micromechanical and phenomenological models were used to fit density-pressure relations. Arzt model describes the powder compaction with good agreement up to D ~ 0.85. Kawakita equation results as a best linear fit for all tests, but its compressibility parameter b is not in agreement with the hardening behavior of the composite. Panelli and Ambrosio equation could describe the data fairly well qualitatively for all compactions tests, however, over a limited pressure range. Finally, Konopicky relationship turned out to be very useful and fitted the densification data of all three materials quite well. Its slope from linear P vs. ln (1/(1 - D)) plots, is related to the yield stress and characterizes the work hardening developed during plastic deformation while the density was increased. Microhardness values increase with the compacting pressure and such tendency agrees with the rising values of yield stresses, obtained by Konopicky. © 2010 Elsevier B.V.

Campanella A.,CONICET | Rustoy E.,UMYMFOR | Baldessari A.,UMYMFOR | Baltanas M.A.,CONICET
Bioresource Technology | Year: 2010

This work reports laboratory results obtained from the production of polyols with branched ether and ester compounds from epoxidized vegetable oils pertaining to annual, temperate climate crops (soybean, sunflower and high-oleic sunflower oils), focusing on their possible use as components of lubricant base stocks. To this end, two different opening reactions of the epoxide ring were studied. The first caused by the attack with glacial acetic acid (exclusively in a single organic phase) and the second using short-chain aliphatic alcohols, methanol and ethanol, in acid media. Both reactions proceed under mild conditions: low synthesis temperature and short reaction times and with conversions above 99%. Spectroscopic (NMR), thermal (DSC) and rheological techniques were used to characterize the oils, their epoxides and polyols, to assess the impact of the nature of the vegetable oil and the chemical modifications introduced, including long-term storage conditions. Several correlations were employed to predict the viscosity of the vegetable oils with temperature, and good agreement with the experimental data was obtained. © 2009 Elsevier Ltd. All rights reserved.

Lopez-Pamies O.,State University of New York at Stony Brook | Idiart M.I.,National University of La Plata | Idiart M.I.,CONICET | Nakamura T.,State University of New York at Stony Brook
Journal of the Mechanics and Physics of Solids | Year: 2011

It is by now well established that loading conditions with sufficiently large triaxialities can induce the sudden appearance of internal cavities within elastomeric (and other soft) solids. The occurrence of such instabilities, commonly referred to as cavitation, can be attributed to the growth of pre-existing defects into finite sizes. This paper introduces a new theory to study the phenomenon of cavitation in soft solids that: (i) allows to consider general 3D loading conditions with arbitrary triaxiality, (ii) applies to large (including compressible and anisotropic) classes of nonlinear elastic solids, and (iii) incorporates direct information on the initial shape, spatial distribution, and mechanical properties of the underlying defects at which cavitation can initiate. The basic idea is to first cast cavitation in elastomeric solids as a homogenization problem of nonlinear elastic materials containing random distributions of zero-volume cavities, or defects. This problem is then addressed by means of a novel iterated homogenization procedure, which allows to construct solutions for a specific, yet fairly general, class of defects. These include solutions for the change in size of the defects as a function of the applied loading conditions, from which the onset of cavitation - corresponding to the event when the initially infinitesimal defects suddenly grown into finite sizes - can be readily determined. In spite of the generality of the proposed approach, the relevant calculations amount to solving tractable HamiltonJacobi equations, in which the initial size of the defects plays the role of time and the applied load plays the role of space. When specialized to the case of hydrostatic loading conditions, isotropic solids, and defects that are vacuous and isotropically distributed, the proposed theory recovers the classical result of Ball (1982) for radially symmetric cavitation. The nature and implications of this remarkable connection are discussed in detail. © 2011 Elsevier Ltd. All rights reserved.

Gennari F.C.,CONICET | Gennari F.C.,Instituto Balseiro | Gennari F.C.,Bariloche Atomic Center
International Journal of Hydrogen Energy | Year: 2012

In the present study, the synthesis of two different LiBH 4-Y(BH4)3 and LiBH4-YH3 composites was performed by mechanochemical processing of the 4LiBH 4-YCl3 mixture and as-milled 4LiBH4-YCl 3 plus 3LiH. It was found that Y(BH4)3 and YH3 formed in situ during milling are effective to promote LiBH 4 destabilization but differ substantially from each other in terms of the dehydrogenation pathway. During LiBH4-Y(BH4) 3 dehydriding, Y(BH4)3 decomposes first generating in situ freshly YH3 and subsequently, it destabilizes LiBH4 with the formation of minor amounts of YB4. About 20% of the theoretical hydrogen storage was obtained via the rehydriding of YB4-4LiH-3LiCl at 400 °C and 6.5 MPa. As a novel result, a compound containing (B12H12)2- group was identified during dehydriding of Y(BH4)3. In the case of 4LiBH4-YH3 dehydrogenation, the increase of the hydrogen back pressure favors the formation of crystalline YB4, whereas a reduction to ≤0.1 MPa induces the formation of minor amounts of Li 2B12H12. Although for hydrogen pressures ≤0.1 MPa direct LiBH4 decomposition can occur, the main dehydriding pathway of 4LiBH4-YH3 composite yields YB 4 and LiH. The nanostructured composite obtained by mechanochemical processing gives good hydrogen storage reversibility (about 80%) regardless of the hydrogen back pressure. Copyright © 2012, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.

Nunez M.A.,CONICET | Dickie I.A.,Landcare Research | Dickie I.A.,Lincoln University at Christchurch
Biological Invasions | Year: 2014

Most plants require mutualistic associations to survive, which can be an important limitation on their ability to become invasive. There are four strategies that permit plants to become invasive without being limited by a lack of mutualists. One is to not be dependent on mutualists. The other three strategies are to form novel mutualisms, form associations with cosmopolitan species, or co-invade with mutualists from their native range. Historically there has been a bias to study mutualisms from a plant perspective, with little consideration of soil biota as invasive species in their own right. Here we address this by reviewing the literature on belowground invasive mutualists of woody plants. We focus on woody invaders as ecosystem-transforming plants that frequently have a high dependence on belowground mutualists. We found that co-invasions are common, with many ectomycorrhizal plant species and N-fixing species co-invading with their mutualists. Other groups, such as arbuscular mycorrhizal plants, tend to associate with cosmopolitan fungal species or to form novel associations in their exotic range. Only limited evidence exists of direct negative effects of co-invading mutualists on native mutualist communities, and effects on native plants appear to be largely driven by altered environmental conditions rather than direct interactions. Mutualists that introduce novel ecosystem functions have effects greater than would be predicted based solely on their biomass. Focusing on the belowground aspects of plant invasions provides novel insights into the impacts, processes and management of invasions of both soil organisms and woody plant species. © 2013 Springer Science+Business Media Dordrecht.

In conflicts between primate groups, the resource-holding potential (RHP) of competitors is frequently related to group size or male group size, which can remain relatively constant for long periods of time, promoting stable intergroup dominance relationships. Demographic changes in neighboring groups, however, could introduce uncertainty into existing relationships. Among tufted capuchin monkeys (Cebus apella nigritus), dominant male replacement is a relatively infrequent demographic event that can have a profound effect on both the composition and size of the social group. Here, we report such a case and the consequences for home range use and intergroup aggression. Between June 2008 and August 2010, we periodically followed two neighboring groups (Macuco and Rita) in Iguazú National Park, recording daily paths (N = 143) and encounters between the groups (N = 28). We describe the events leading to a change in the male dominance hierarchy in the larger group (Macuco), which resulted in the death or dispersal of all adult males, followed by the succession of a young adult male to the dominant position. This takeover event reduced the numerical advantage in number of males between the two groups, although the ratio of total group sizes remained nearly constant. Following this shift in numerical asymmetry, the degree of escalation of intergroup aggression increased, and we observed reversals in the former intergroup dominance relationship. These changes in behavior during intergroup encounters were associated with changes in the use of overlapping areas. In the 6 months following the takeover, the area of home range overlap doubled, and the formerly dominant group's area of exclusive access was reduced by half. These results suggest that RHPin tufted capuchin monkeys is related to male group size. Furthermore, they highlight the importance of considering rare demographic events in attempts to understand the dynamics of aggression between primate groups. © 2012 Wiley Periodicals, Inc.

In Northern Patagonia, the long-term vegetation-climate relationships that gave shape to southern South American forests have been the subject of extensive investigations in the Andean regions of Argentina and Chile for about a century. The Río Manso Superior originates in one of the tongues of the Cerro Tronador Glacier, near the international border, discharging into the Pacific Ocean after feeding present Lago Mascardi and flowing east to west on a mountain landscape. Ongoing pollen studies in this watershed provide us with a modern analogue to better understand the vegetation history of the region. A pollen record from a 15 m long sediment core retrieved from Lago Mascardi (41°08°S, 71°34°W) contains continuous evidence of vegetation changes in the Río Manso watershed extending back to the last deglaciation. High Andean steppe vegetation with forest patches, and extended waterlogged areas gave place to a forest, probably deciduous, during the Lateglacial-Holocene transition. A forest diversification took place during the climate amelioration that encompassed the deglaciation whilst the vegetation became more open before the onset of the Huelmo-Mascardi cold reversal. A mixed Nothofagus-Austrocedrus forest expanded during the middle Holocene. This forest became denser under the higher climate variability registered in the region during the late Holocene as shown by independent published data. Statistical analyses of modern pollen samples along an altitudinal transect from low Nothofagus forest and shrubland to high Andean semi-desert support this interpretation. Pollen results are discussed in the context of paleoenvironmental reconstructions at a regional scale. © The Author(s) 2011.

Gudesblat G.E.,Vlaams Institute for Biotechnology | Gudesblat G.E.,Ghent University | Gudesblat G.E.,CONICET | Russinova E.,Vlaams Institute for Biotechnology | Russinova E.,Ghent University
Current Opinion in Plant Biology | Year: 2011

Brassinosteroids (BRs) are plant steroid hormones known mainly for promoting organ growth through their combined effect on cell expansion and division. In addition, BRs regulate a broad spectrum of plant developmental and physiological responses, including plant architecture, vascular differentiation, male fertility, flowering, senescence, photomorphogenesis and tolerance to biotic and abiotic stresses. Recently, a complete core BR signaling pathway was defined in which BR signals are conveyed from the cell surface to the nucleus through sequential signaling modules. A major challenge now is to understand precisely how this signaling pathway controls the different BR-regulated actions. The current identification of direct targets of BRASSINAZOLE-RESISTANT1 (BRZ1) and BR-INSENSITIVE-EMS-SUPPRESSOR1 (BES1)/BZR2 transcription factors suggests that BR signaling pathway controls growth and interacts with other signaling pathways mainly at the transcriptional level. © 2011 Elsevier Ltd.

Hohm O.,State University of New York at Stony Brook | Marques D.,CONICET
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2016

We develop the perturbation theory of double field theory around arbitrary solutions of its field equations. The exact gauge transformations are written in a manifestly background covariant way and contain at most quadratic terms in the field fluctuations. We expand the generalized curvature scalar to cubic order in fluctuations and thereby determine the cubic action in a manifestly background covariant form. As a first application we specialize this theory to group manifold backgrounds, such as SU(2)≃S3 with H-flux. In the full string theory this corresponds to a Wess-Zumino-Witten background CFT. Starting from closed string field theory, the cubic action around such backgrounds has been computed before by Blumenhagen, Hassler, and Lüst. We establish precise agreement with the cubic action derived from double field theory. This result confirms that double field theory is applicable to arbitrary curved background solutions, disproving assertions in the literature to the contrary. © 2016 American Physical Society.

Perez-Piskunow P.M.,National University of Cordoba | Usaj G.,Bariloche Atomic Center | Usaj G.,CONICET | Balseiro C.A.,Bariloche Atomic Center | And 2 more authors.
Physical Review B - Condensed Matter and Materials Physics | Year: 2014

We report on the emergence of laser-induced chiral edge states in graphene ribbons. Insights on the nature of these Floquet states is provided by an analytical solution which is complemented with numerical simulations of the transport properties. Guided by these results we show that graphene can be used for realizing nonequilibrium topological states with striking tunability: while the laser intensity can be used to control their velocity and decay length, changing the laser polarization switches their propagation direction. © 2014 American Physical Society.

Perez-Piskunow P.M.,National University of Cordoba | Foa Torres L.E.F.,National University of Cordoba | Usaj G.,Bariloche Atomic Center | Usaj G.,CONICET
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2015

Electromagnetic driving in a honeycomb lattice can induce gaps and topological edge states with a structure of increasing complexity as the frequency of the driving lowers. While the high-frequency case is the most simple to analyze we focus on the multiple photon processes allowed in the low-frequency regime to unveil the hierarchy of Floquet edge states. In the case of low intensities an analytical approach allows us to derive effective Hamiltonians and address the topological character of each gap in a constructive manner. At high intensities we obtain the net number of edge states, given by the winding number, with a numerical calculation of the Chern numbers of each Floquet band. Using these methods, we find a hierarchy that resembles that of a Russian nesting doll. This hierarchy classifies the gaps and the associated edge states in different orders according to the electron-photon coupling strength. For large driving intensities, we rely on the numerical calculation of the winding number, illustrated in a map of topological phase transitions. The hierarchy unveiled with the low-energy effective Hamiltonians, along with the map of topological phase transitions, discloses the complexity of the Floquet band structure in the low-frequency regime. The proposed method for obtaining the effective Hamiltonian can be easily adapted to other Dirac Hamiltonians of two-dimensional materials and even the surface of a three-dimensional topological insulator. © 2015 American Physical Society.

Aldazabal G.,Bariloche Atomic Center | Aldazabal G.,CONICET | Marques D.,CONICET | Nunez C.,CONICET | Nunez C.,University of Buenos Aires
Classical and Quantum Gravity | Year: 2013

Double field theory (DFT) is a proposal to incorporate T-duality, a distinctive symmetry of string theory, as a symmetry of a field theory defined on a double configuration space. The aim of this review is to provide a pedagogical presentation of DFT and its applications. We first introduce some basic ideas on T-duality and supergravity in order to proceed to the construction of generalized diffeomorphisms and an invariant action on the double space. Steps towards the construction of a geometry on the double space are discussed. We then address generalized Scherk-Schwarz compactifications of DFT and their connection to gauged supergravity and flux compactifications. We also discuss U-duality extensions and present a brief parcours on worldsheet approaches to DFT. Finally, we provide a summary of other developments and applications that are not discussed in detail in the review. © 2013 IOP Publishing Ltd.

Romero M.,CONICET | Aligia A.A.,Bariloche Atomic Center
Physical Review B - Condensed Matter and Materials Physics | Year: 2011

We consider a Hubbard-Anderson model which describes localized orbitals in five different sites hybridized both among themselves and with a continuum of extended states. A square planar geometry with an atom at the center is used to represent TBrPP-Co molecules. When the renormalized effective hopping between sites is small compared with a Kondo energy scale determined by the site-continuum hybridization, the system can be described as a set of independent Kondo resonances, rather than molecular states. We study the crossover between both regimes and analyze the spectral density of conduction electrons as a function of position. The results are in qualitative agreement with measurements of the differential conductance in a system with TBrPP-Co molecules adsorbed on a Cu(111) surface. © 2011 American Physical Society.

Gennari F.C.,CONICET | Gennari F.C.,Bariloche Atomic Center
Journal of Alloys and Compounds | Year: 2013

A new erbium borohydride Er(BH4)3 was synthesized from 3LiBH4 and ErCl3 through mechanochemical processing. This rare-earth metal borohydride presents a primitive cubic structure with a = 10.74(1) A, which is isostructural with the one previously reported for R(BH4)3 (R = Y, Dy and Gd). During heating Er(BH4)3 exhibits a reversible structural transformation at about 220 °C, analogous to that observed for Y(BH4)3. Combination of thermal hydrogen desorption, DSC, XRPD and FTIR measurements allows to determine that thermal decomposition of Er(BH4)3 starts at 230 °C and leads to 3.2 wt% of hydrogen release obtaining ErH2, an unknown intermediate compound and ErB4. It was observed that Er(BH 4)3 is partially reversible under 6.0 MPa of H2 at 400 °C and absorbs about 20% of the total hydrogen capacity obtained experimentally. © 2013 Elsevier B.V. All rights reserved.

Conicet, Inis Biotech Llc and Fundacion Instituo Leloir | Date: 2010-12-02

Vaccine against neoplastic or cancerous lesions caused by human papillomavirus (HPV), which comprises E7 peptide spherical particles and, as an option, an adjuvant, where spherical particles may be oligomeric. The oligomeric spherical particles may have a diameter in the vicinity of 50 nm and a molecular weight in the vicinity of 700 kDa. The vaccine may be helpful to prevent or treat human papillomavirus (HPV)-related lesions or do both things at the same time.

News Article | August 31, 2016
Site: www.techtimes.com

Scientists have found a fossilized skull of a new species of pterosaur in Argentina's Patagonia region. The previously unknown species has been named "Allkaruen koi." The flying reptile, believed to be the oldest pterosaur that lived during the early Jurassic period, thrived between 199.6 million years and 175.6 million years ago. The now-extinct pterosaurs were very well adapted to flight as suggested by their lightweight bones. An earlier study also found that these creatures have air sacs extending from the lungs to keep the body's density down. The Allkaruen koi also featured an elongated digit that supported a wing membrane. Scientists, however, know very little about these ancient creatures because of poor fossil records. Fortunately, an intact braincase was discovered along with the fossil remains, giving scientists a better chance at looking into the neuroanatomy of the creature more closely. The fossils of the flying reptile were discovered in a bone bed with other pterosaur remains. The skull measured only about 7 centimeters (2.75 inches) long, which means that the Allkaruen koi was a small species of pterosaur. Some species of pterosaurs were tiny but others could grow to the size of giraffes. The larger ones may have used their limbs to leapfrog when they fly. Archaeologists were also able to unearth a vertebra and jaws. "Compared to the other similar species we know of, this one is about the size of an egret, but it's very difficult to know exactly, since we only have parts of the skull and some neck vertebrae," said study researcher Ariana Carabajal, from the Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) in Argentina. By using computed tomography scans, Carabajal and colleagues built digital models of the animal's inner ear and the interior of the skull, which helped find the place of the Allkaruen koi in the pterosaur family tree. The researchers said it is rare to find an intact pterosaur and there is much to know about the evolution of pterosaur skulls and brains over time. Researchers learned that some of features of the skull of the Pterodactylus, a genus of pterosaurs, evolved by the early to middle Jurassic period. "Allkaruen, from the middle lower Jurassic limit, shows an intermediate state in the brain evolution of pterosaurs and their adaptations to the aerial environment," noted paleontologist Diego Pol, another member of the research team. "As a result, this research makes an important contribution to the understanding of the evolution of all of pterosaurs." Details of the find are published in the journal PeerJ on Aug. 30. © 2016 Tech Times, All rights reserved. Do not reproduce without permission.

Saraceno M.,CONICET | Provost C.,University Pierre and Marie Curie
Deep-Sea Research Part I: Oceanographic Research Papers | Year: 2012

Eddies in the southwestern Atlantic were detected from more than 18 years of satellite altimetry data using a modified version of the Okubo-Weiss method. The spatial distribution and polarity of eddies were examined. A larger concentration of cyclonic (anticyclonic) eddies was found on the left (right) side when looking downstream on some of the largest current systems in the region, such as the South Atlantic Current, the anticyclonic circulation associated with the Zapiola Drift (ZD) and the northern branch of the Antarctic Circumpolar Current. In the region isolated by the anticyclonic Zapiola Current, 91% of eddies were cyclonic. The observed distribution of eddies is in agreement with the generation of eddies from meanders of the above-mentioned currents: cyclonic (anticyclonic) eddies might detach from a meander of the current on the left (right) side when looking downstream on the current. Furthermore, in the ZD area, the bottom topography plays a key role in determining the trajectory of eddies: the anticyclonic current associated with the ZD meanders and eventually generates a cyclonic eddy that enters the ZD region only across the northeastern border, where the gradient of potential vorticity is lower. Finally, average surface chlorophyll-a concentration inside cyclonic and anticyclonic eddies shows that the former have higher chlorophyll-a values. Thus, on average, the classical eddy-pumping theory explains the difference in chlorophyll-a concentration within eddies in the southwestern Atlantic. © 2012 Elsevier Ltd.

Olivieri A.C.,CONICET | Faber K.,Chemometry Consultancy
Analytical Chemistry | Year: 2012

Appropriate closed-form expressions are known for estimating analyte sensitivities when calibrating with one-, two-, and three-way data (vectors, matrices, and three-dimensional arrays, respectively, built with data for a group of samples). In this report, sensitivities are estimated for calibration with four-way data using the quadrilinear parallel factor (PARAFAC) model, making it possible to assess important figures of merit for method comparison or optimization. The strategy is based on the computation of the uncertainty in the fitted PARAFAC parameters through the Jacobian matrix. Extensive Monte Carlo noise addition simulations in four-way data systems having widely different overlapping situations are helpful in supporting the present approach, which was also applied to two experimental analytical systems. With this proposal, the estimation of the PARAFAC sensitivity for calibration scenarios involving three- and four-way data may be considered complete. © 2011 American Chemical Society.

Lichtenstein R.G.,Ben - Gurion University of the Negev | Rabinovich G.A.,CONICET | Rabinovich G.A.,Laboratorio Of Glicomica Funcional
Cell Death and Differentiation | Year: 2013

Although one typically thinks of carbohydrates as associated with cell growth and viability, glycosylation also has an integral role in many processes leading to cell death. Glycans, either alone or complexed with glycan-binding proteins, can deliver intracellular signals or control extracellular processes that promote initiation, execution and resolution of cell death programs. Herein, we review the role of glycans and glycan-binding proteins as essential components of the cell death machinery during physiologic and pathologic settings. © 2013 Macmillan Publishers Limited All rights reserved.

Montemurro M.A.,University of Manchester | Zanette D.H.,CONICET
PLoS ONE | Year: 2011

Background: The language faculty is probably the most distinctive feature of our species, and endows us with a unique ability to exchange highly structured information. In written language, information is encoded by the concatenation of basic symbols under grammatical and semantic constraints. As is also the case in other natural information carriers, the resulting symbolic sequences show a delicate balance between order and disorder. That balance is determined by the interplay between the diversity of symbols and by their specific ordering in the sequences. Here we used entropy to quantify the contribution of different organizational levels to the overall statistical structure of language. Methodology/Principal Findings: We computed a relative entropy measure to quantify the degree of ordering in word sequences from languages belonging to several linguistic families. While a direct estimation of the overall entropy of language yielded values that varied for the different families considered, the relative entropy quantifying word ordering presented an almost constant value for all those families. Conclusions/Significance: Our results indicate that despite the differences in the structure and vocabulary of the languages analyzed, the impact of word ordering in the structure of language is a statistical linguistic universal. © 2011 Montemurro, Zanette.

Diogo R.,Howard University | Linde-Medina M.,University of Manchester | Abdala V.,CONICET | Ashley-Ross M.A.,Wake forest University
Biological Reviews | Year: 2013

Most textbooks and research reports state that the structures of the tetrapod forelimbs and hindlimbs are serial homologues. From this view, the main challenge of evolutionary biologists is not to explain the similarity between tetrapod limbs, but instead to explain why and how they have diverged. However, these statements seem to be related to a confusion between the serial homology of the vertebrate pelvic and pectoral appendages as a whole, and the serial homology of the specific soft- and hard-tissue structures of the tetrapod forelimbs and hindlimbs, leading to an even more crucial and puzzling question being overlooked: why are the skeletal and particularly the muscle structures of the forelimb and hindlimb actually so strikingly similar to each other? Herein we provide an updated discussion of these questions and test two main hypotheses: (i) that the similarity of the limb muscles is due to serial homology; and (ii) that tetrapods that use hindlimbs for a largely exclusive function (e.g. bipedalism in humans) exhibit fewer cases of similarity between forelimbs and hindlimbs than do quadrupedal species. Our review shows that of the 23 arm, forearm and hand muscles/muscle groups of salamanders, 18 (78%) have clear 'topological equivalents' in the hindlimb; in lizards, 14/24 (58%); in rats, 14/35 (40%); and in modern humans, 19/37 (51%). These numbers seem to support the idea that there is a plesiomorphic similarity and subsequent evolutionary divergence, but this tendency actually only applies to the three former quadrupedal taxa. Moreover, if one takes into account the total number of 'correspondences', one comes to a surprising and puzzling conclusion: in modern humans the number of forelimb muscles/muscle groups with clear 'equivalents' in the hindlimb (19) is substantially higher than in quadrupedal mammals such as rats (14), lizards (14) and even salamanders (18). These data contradict the hypothesis that divergent functions lead to divergent morphological structures. Furthermore, as we show that at least five of the 19 modern human adult forelimb elements that have a clear hindlimb 'equivalent' derive from embryonic anlages that are very different from the ones giving rise to their adult hindlimb 'equivalents', they also contradict the hypothesis that the similarity in muscle structures between the forelimb and hindlimb of tetrapods such as modern humans are due to their origin as serial homologues. This similarity is instead the result of phylogenetically independent evolutionary changes leading to a parallelism/convergence due to: (i) developmental constraints, i.e. similar molecular mechanisms are involved (particularly in the formation of the neomorphic hand), but this does not necessarily mean that similar anlages are used to form the similar adult structures; (ii) functional constraints, related to similar adaptations; (iii) topological constraints, i.e. limited physical possibilities; and even (iv) phylogenetic constraints, which tend to prevent/decrease the occurrence of new homoplasic similarities, but also help to keep older, ancestral homoplasic resemblances. © 2012 Cambridge Philosophical Society.

Langguth B.,University of Regensburg | Elgoyhen A.B.,CONICET | Elgoyhen A.B.,University of Buenos Aires
Expert Opinion on Pharmacotherapy | Year: 2012

Introduction: Tinnitus, the phantom perception of sound, is a highly prevalent disorder and treatment is elusive. Areas covered: This review focuses on clinical research regarding pharmacological treatments for tinnitus. The authors searched PubMed databases for English language articles related to pharmacological treatment of tinnitus, published through August 2012. The keywords tinnitus AND pharmacological treatment" and "tinnitus AND drugs" were used. The search focused on clinical trials, but was complemented by other articles and information from clinical trial registries. Expert opinion: Despite the significant unmet clinical need for a safe and effective drug for tinnitus relief, there is currently no EMA- or FDA-approved drug on the market. Even a drug that produces a small but significant effect would have a huge therapeutic impact. At present, evidence-based pharmacological approaches are limited to the treatment of comorbidities such as depression, anxiety, or insomnia. In the last few years there have been significant advances in the understanding of the pathophysiology of the different forms of tinnitus, the establishment of valid animal models, and the development of clinical trial methodology. A glimpse of hope is appearing in the horizon as an increasing number of pharmaceutical industries now have compounds targeting tinnitus in their pipeline. © Informa UK, Ltd.

Ibanez A.,University of Buenos Aires | Ibanez A.,Diego Portales University | Manes F.,University of Buenos Aires | Manes F.,CONICET
Neurology | Year: 2012

The significance of social situations is commonly context-embedded. Although the role of context has been extensively studied in basic sensory processing or simple stimulus-response settings, its relevance for social cognition is unknown. We propose the social context network model (SCNM), a fronto-insular-temporal network responsible for processing social contextual effects. The SCNM may 1) update the context and use it to make predictions, 2) coordinate internal and external milieus, and 3) consolidate context-target associative learning. We suggest the behavioral variant of frontotemporal dementia (bvFTD) as a specific disorder in which the reported deficits in social cognition (e.g., facial recognition, empathy, decisionmaking, figurative language, theory of mind) can be described as context impairments due to deficits in the SCNM. Disruption of orbitofrontal-amygdala circuit, as well as the frontal, temporal, and insular atrophy in bVFTD, suggests a relationship between context-sensitive social cognition and SCNM. In considering context as an intrinsic part of social cognition, we highlight the need for a situated cognition approach in social cognition research as opposed to an abstract, universal, and decontextualized approach. The assessment of context-dependent social cognition paradigms, the SCNM, and their possible application to neuropsychiatric disorders may provide new insight into bvFTD and other related frontal disorders. Copyright © 2012 by AAN Enterprises, Inc.

Ciocca D.R.,CONICET | Arrigo A.P.,Regional Development Centre | Calderwood S.K.,Beth Israel Deaconess Medical Center
Archives of Toxicology | Year: 2013

Heat shock proteins (HSP) are a subset of the molecular chaperones, best known for their rapid and abundant induction by stress. HSP genes are activated at the transcriptional level by heat shock transcription factor 1 (HSF1). During the progression ofmany types of cancer, this heat shock transcriptional regulon becomes co-opted by mechanisms that are currently unclear, although evidently triggered in the emerging tumor cell. Concerted activation of HSF1 and the accumulation of HSPs then participate in many of the traits that permit the malignant phenotype. Thus, cancers of many histologies exhibit activated HSF1 and increased HSP levels that may help to deter tumor suppression and evade therapy in the clinic. We review here the extensive work that has been carried out and is still in progress aimed at (1) understanding the oncogenic mechanisms by which HSP genes are switched on, (2) determining the roles of HSF1/HSP in malignant transformation and (3) discovering approaches to therapy based on disrupting the influence of the HSF1-controlled transcriptome in cancer. © The Author(s) 2012.

Valero-Mora P.M.,University of Valencia | Ledesma R.D.,CONICET
Journal of Statistical Software | Year: 2012

Since R was first launched, it has managed to gain the support of an ever-increasing percentage of academic and professional statisticians. However, the spread of its use among novice and occasional users of statistics have not progressed at the same pace, which can be atributed partially to the lack of a graphical user interface (GUI). Nevertheless, this situation has changed in the last years and there is currently several projects that have added GUIs to R. This article discusses brie y the history of GUIs for data analysis and then introduces the papers submitted to an special issue of the Journal of Statistical Software on GUIs for R.

Marco D.E.,National University of Costa Rica | Montemurro M.A.,University of Manchester | Cannas S.A.,CONICET
Ecography | Year: 2011

Dispersal is a factor of great importance in determining a species spatial distribution. Short distance dispersal (SDD) and long distance dispersal (LDD) strategies yield very different spatial distributions. In this paper we compare spatial spread patterns from SDD and LDD simulations, contrast them with patterns from field data, and assess the significance of biological and population traits. Simulated SDD spread using an exponential function generates a single circular patch with a well-defined invasion front showing a travelling-wave structure. The invasive spread is relatively slow as it is restricted to reproductive individuals occupying the outer zone of the circular patch. As a consequence of this dispersal dynamics, spread is slower than spread generated by LDD. In contrast, the early and fast invasion of the entire habitat mediated by power law LDD not only involves a significantly greater invasion velocity, but also an entirely different habitat occupation. As newly dispersed individuals soon reach very distant portions of the habitat as well as the vicinity of the original dispersal focus, new growing patches are generated while the main patch increases its own growth absorbing the closest patches. As a consequence of both dispersal and lower density dependence, growth of the occupied area is much faster than with SDD. SDD and LDD also differ regarding pattern generation. With SDD, fractal patterns appear only in the border of the invasion front in SDD when competitive interaction with residents is included. In contrast, LDD patterns show fractality both in the spatial arrangements of patches as well as in patch borders. Moreover, values of border fractal dimension inform on the dispersal process in relation with habitat heterogeneity. The distribution of patch size is also scale-free, showing two power laws characteristic of small and large patch sizes directly arising from the dispersal and reproductive dynamics. Ecological factors like habitat heterogeneity are relevant for dispersal, although its importance is greater for SDD, lowering the invasion velocity. Among the life history traits considered, adult mortality, the juvenile bank and mean dispersal distance are the most relevant for SDD. For LDD, habitat heterogeneity and changes in life history traits are not so relevant, causing minor changes in the values of the scale-free parameters. Our work on short and long distance dispersal shows novel theoretical differences between SDD and LDD in invasive systems (mechanisms of pattern formation, fractal and scaling properties, relevance of different life history traits and habitat variables) that correspond closely with field examples and were not analyzed, at least in this degree of detail, by the previously existing models. © 2011 The Authors. Ecography © 2011 Ecography.

Espi Huerta J.M.,University of Valencia | Castello J.,University of Valencia | Fischer J.R.,CONICET | Garcia-Gil R.,University of Valencia
IEEE Transactions on Industrial Electronics | Year: 2010

This paper presents a new predictive current control for three-phase grid-connected inverters in the synchronous reference frame. The control combines a deadbeat control law with a diagonal Luenberger observer to estimate the future value of the grid currents. It provides a decoupled control of the active and reactive power and offers robustness against the computational delay inherent in the digital implementation and against filter and grid-impedance uncertainties. This control exhibits a very fast current response while widely improving the gain and phase margins of the traditional predictive controllers. © 2006 IEEE.

Oelbermann M.,University of Waterloo | Echarte L.,CONICET
European Journal of Soil Science | Year: 2011

The Pampa comprises the most productive land in Argentina, but the widespread adoption of sole cropping has drastically reduced soil organic carbon (SOC) stocks. This paper presents baseline data on the effects of maize-legume inter-crops compared with maize and soyabean sole crops on SOC and nitrogen (N) stocks, gross SOC turnover, soil microbial biomass (SMB), soil organic matter light fraction (LF) and the partitioning of carbon (C) derived from C3- and C4 crops into SOC, LF and SMB. For soil characteristics, only the C:N ratio was significantly different (0-120 cm) between treatments. Gross SOC and SMB-C turnover time (0-120 cm) was faster in the maize sole crop followed by the inter-crops and the soyabean sole crop. The SMB-C and N were significantly greater in the intercrops. Soil LF-N (0-20 cm) was significantly smaller in the inter-crop. Soil became significantly enriched (0-120 cm) in δ15N in the inter-crop, suggesting that microbial decomposers incorporated C derived from maize and soyabean residues. The greatest proportion of C in the soil and in the soil LF was derived from a C4-C source, and the δ13C of the SMB (0-20 cm) was enriched compared with that of the SOC and the soil LF. Results from this study indicated that after only 1 year of inter-cropping, soil biological and chemical characteristics were influenced positively by this land management practice. © 2010 The Authors. Journal compilation © 2010 British Society of Soil Science.

Gonzalez-Suarez M.,CSIC - Doñana Biological Station | Cassini M.H.,CONICET | Cassini M.H.,University of Buenos Aires
Mammal Review | Year: 2014

The theory of evolution by sexual selection for sexual size dimorphism (SSD) postulates that SSD primarily reflects the adaptation of males and females to their different reproductive roles. For example, competition among males for access to females increases male body size because larger males are better able to maintain dominant status than smaller males. Larger dominant males sire most offspring while smaller subordinate males are unsuccessful, leading to skew in reproductive success. Therefore, species with male-biased SSD are predicted to have greater variance in male reproductive success than those in which both sexes are similar in size. We tested this prediction among the Pinnipedia, a mammalian group with a great variation in SSD. From a literature review, we identified genetic estimates of male reproductive success for 10 pinniped taxa (eight unique species and two subspecies of a ninth species) that range from seals with similarly sized males and females to species in which males are more than four times as large as females. We found no support for a positive relationship between variance in reproductive success and SSD among pinnipeds after excluding the elephant seals Mirounga leonina and Mirounga angustirostris, which we discuss as distinctive cases. Several explanations for these results are presented, including the revival of one of Darwin's original ideas. Darwin proposed that natural selection may explain SSD based on differences in energetic requirements between sexes and the potential for sexual niche segregation. Males may develop larger bodies to exploit resources that remain unavailable to females due to the energetic constraints imposed on female mammals by gestation and lactation. The importance of this alternative explanation remains to be tested. © 2013 The Mammal Society and John Wiley & Sons Ltd.

French Institute of Health, Medical Research, French National Center for Scientific Research, Catholic University of Córdoba, Assistance Publique Hopitaux De Paris, Conicet, University Pierre and Marie Curie | Date: 2011-03-29

The invention relates to pharmaceutical compositions using a polypeptide comprising at least one CXXC motif, such as Giardia parasites variable surface proteins (VSP) or a fragment thereof to raise by oral or mucosal vaccination an immune response against a heterologous selected antigen, such as tumor antigen, microbial antigen or other antigen.

Agency: European Commission | Branch: FP7 | Program: CP-FP | Phase: SSH.2012.8.8-1 | Award Amount: 3.17M | Year: 2013

INTERCO-SSH sets out, firstly, to assess the state of the SSH in Europe. Secondly, it aims to outline potential future pathways that would promote cooperation across disciplinary and national boundaries. To achieve this, it is necessary to study the SSH in their socio-historical context. The project will analyze the process of institutionalization of seven disciplines - sociology/demography, economics, anthropology, political science, philosophy, literary studies, psychoanalysis - to obtain an understanding of the sociological factors that have shaped the academic unconscious of scholars and that facilitate or hinder intellectual cooperation and exchange. Attention will be paid to the relationship between the SSH and political and economic powers. The project will also investigate the already existing circulation of knowledge between countries and disciplines, encompassing an analysis of geographical mobility amongst scholars and an assessment of the circulation of ideas. The project sets out to develop a comparative analysis of the institutionalization of the SSH in at least six European countries (UK, France, Germany, Italy, Netherlands, Hungary) from 1945 to date. It will also analyze exchanges between those countries and other areas: the US, Latin-America, and Africa. The approach will combine three perspectives; it will: 1) construct patterns of institutionalization of the SSH; 2) map the exchanges between countries and disciplines; 3) study the circulation of paradigms, theories and controversies. These three perspectives will help to identify the factors that enable or inhibit intellectual cooperation and to make policy-relevant suggestions to improve it. Using the tools of the SSH to study the SSH, this project also aims to help establish the SSH studies as a proper academic field of inquiry, providing the scientific means for assessing and guiding the development of the SSH, and for strengthening the European Research Area.

Agency: European Commission | Branch: FP7 | Program: CP-FP-SICA | Phase: NMP.2011.2.3-1 | Award Amount: 3.98M | Year: 2012

Polyhydroxyalkanoates (PHAs), naturally produced polyesters, are gaining attention in the biodegradable polymer market due to their high biodegradability and versatility. They display sufficient functional properties to replace some of the 250 MTs of plastics used worldwide today, especially in the substitution of PET, which is widely used in soft drink bottles to electronics casing. A key challenge is in producing PHAs that are cost and performance competitive with conventional fossil-based polymers. Recent research has discovered that PHA polymers are naturally produced by some bacteria within the bacterial cell and can be extracted or processed for use in many applications-packaging, moulded goods, adhesives, films, etc. Work has been underway to determine if they can be grown in genetically modified plants. Despite positive results, many publications and patents on eco-compatible packaging materials, the production of biopolymers from natural sources has been limited, mainly due to difficulties in processing of natural materials, incompatibility at the interface natural fillers-polymeric matrices, poor mechanical properties, possible toxicity due to natural material degradation and moisture sensitivity, high raw material cost, etc. This project will build on promising preliminary research results into the growth of genetically modified cyanobacteria in wastewaters to produce PHAs. Cyanobacteria are a group of oxygen-evolving photosynthetic bacteria with short generation time, and are the sole prokaryotes that accumulate PHA by oxygenic photosynthesis, having potential for PHA cultivation in wastewaters. Olive oil wastewater will be recovered and reused to obtain PHA biopolymers for use as advanced packaging material. A valorisation of the waste materials will be obtained for using the leftover biomass (from biopolymer production) for biodiesel production and for the extraction of chemicals and natural fillers for Polyhydroxybutyrate (PHB)-based composites.

Conicet, French Institute of Health, Medical Research, Catholic University of Córdoba, Assistance Publique Hopitaux De Paris, University Pierre and Marie Curie | Date: 2013-07-05

The invention provides compositions for oral delivery and methods of treatment using VSP carriers, such as Giardia sp. variable surface proteins (VSP), to deliver therapeutic agents. VSP drug carriers can be combined with bioactive peptides, e.g., insulin, glucagon, or hGH, and be administered orally or mucosally. VSP carriers are resistant to acidic pHs and to proteolytic degradation and protect therapeutic agents from degradation in the gastrointestinal tract.

News Article | November 8, 2016
Site: www.npr.org

Pairing Wine And Cheese? Science Says White May Be A Better Choice Than Red Conventional wisdom would have you drink red wine with cheese. A new study, published in the Journal of Food Science, only partially supports that pairing, and also adds a new tool to the scientific study of food combinations. "Red wine with cheese, it can either go really well or not that well," says Mara Galmarini, a sensory scientist at CONICET, the Argentinian National Scientific and Technical Research Council. "A white wine, you have less risk." Ed Behr, editor of the influential Art of Eating newsletter, says he's not surprised. Behr has long argued that red wines and cheeses often fight, to the detriment of both. "There's no question in my mind that white wine goes better. And more often than not, depending on the cheese, a little sweetness makes things even easier," Behr told The Salt. Galmarini spent two years exploring wine and cheese pairings at the Centre des Sciences du Goût et de l'Alimentation (CGSA – Centre for Taste and Feeding Behavior) in Dijon, France. Much of the work was to build on a new technique called temporal dominance of sensations (TDS) that researchers there developed to examine how taste evolves over time. The problem with current methods, Galmarini says, is that they are static and singular. Expert tasters can accurately describe what is in their mouths, often giving a numerical rating to the intensity of each element of the flavor. That doesn't work to chart how the taste of a mouthful changes or how different foods and drinks affect one another. TDS is designed to reveal how the taste of something evolves as you consume it. The taster sits down in front of a computer screen with a black glass of an unknown wine. On the screen are 11 words describing attributes or sensations such as sour, astringent, bitter, floral and so on. Before the test, the tasters are given canonical examples of each sensation – such as a citric acid solution for "sour" and the scent of violets for "floral" – so that they understand exactly what each attribute means. The taster takes a sip and then clicks on whichever sensation is dominant at that moment. When the sensation changes — say, from "sour" to "red fruits" — the tester clicks the new attribute, until there is no sensation left. Then the testers rate how much they like the wine. That's a purely subjective judgment, with no attempt to define what "liking" means. They take another sip and do it all again. After a final sip, the test is over. While the TDS technique is relatively new, it is proving useful. Charles Spence, professor of experimental psychology at Oxford University and an expert on sensory evaluation, told The Salt that "it gives a finer degree of analysis." The temporal evolution of tasting experiences, Spence says, "has been kind of ignored previously, perhaps because it has been harder to get a dynamic sense of how perception is changing." TDS addresses that and, Spence says, is relatively easy. "That's part of its appeal," he said. For Galmarini, too, that is important. "Providing that the attributes are simple enough and well explained," she says "it can be used with consumers." For the experiment, 31 regular consumers of wine and cheese assessed four different wines: a sweet white Pacherenc, a dry white Sancerre, a full-bodied red Bourgogne and a rather tannic red Madiran. Then they did it again, between each sip of wine eating a small bit of cheese, four in all, so each wine was paired with each cheese. The cheeses were a chewy, firm cow's milk Epoisses, a semi-hard cow's milk Comté, a salty, blue-veined sheep's milk Roquefort and a crumbly, goat's milk Crottin de Chavignol. With so many combinations, the detailed results are complex. Nevertheless, Galmarini says there is a clear conclusion for certain sensations, such as sourness and astringency, which would probably be considered negative. "With cheese," she told The Salt, "the sensation is reduced. It does not last so long in the mouth." The reduction in negative sensations is mirrored by changes in likeability. Overall, tasters liked the wines more after the second and third sips with cheese than they did without cheese. The effect was most marked for the Madiran, which was also the wine that tasters liked least after the second and third sips. "I think that's because of an interaction with the fattiness of the cheese," Galmarini said. "It makes a coating in the mouth which reduces the astringency." Although the researchers did not set out to recommend specific pairings, The Salt pressed Dr. Galmarini. Her latest study, as yet unpublished, does offer some advice. "If you have many cheeses, better to serve a white wine," she says. Behr points out that most red wines "are completely unrefreshing." That's fine with a little cheese at the end of a structured meal, to finish the red wine. But Behr says, when the cheese is more than just a taste but "maybe the central protein of the meal, what you want is a drink that's much more refreshing." In other words: a dry white. Galmarini and her colleagues stress that the real value of their study is that it extends the new TDS method to study interactions with food. Spence sees the value in that. "Chefs are becoming more aware of the sequencing of sensations, rather than just combining flavors." The new method will help them understand why some of those sequences work and others don't. For Galmarini, wine and cheese is just a starting point. Whiskey and cigars, wine and chocolate, tea and pastries – all are now in her sights. "There are so many of these traditional pairings that have no sensory science background," she said. "Now we can study them with good data." Jeremy Cherfas is a biologist and science journalist based in Rome.

Goloboff P.A.,CONICET | Simmons M.P.,Colorado State University
Systematic Biology | Year: 2014

When doing a bootstrap analysis with a single tree saved per pseudoreplicate, biased search algorithms may influence support values more than actual properties of the data set. Two methods commonly used for finding phylogenetic trees consist of randomizing the input order of species in multiple addition sequences followed by branch swapping, or using random trees as the starting point for branch swapping. The randomness inherent to such methods is assumed to eliminate any consistent preferences for some trees or unsupported groups of taxa, but both methods can be significantly biased. In the case of trees created by sequentially adding taxa, a bias may occur even if every addition sequence is equiprobable, and if one of the equally optimal positions for each terminal to add to the tree is selected equiprobably. In the case of branch swapping, the bias can happen even when branch swapping equiprobably selects any of the trees of better score in the subtree-pruning-regrafting-neighborhood or tree-bisection-reconnection-neighborhood. Consequently, when the data set is ambiguous, both random-addition sequences and branch swapping from random trees may (i) find some of the optimal trees much more frequently than others and (ii) find some groups with a frequency that differs from their frequency among all optimal trees. When the data set defines a single optimal tree, the groups present in that tree may have a different probability of being found by a search, even if supported by equal amounts of evidence. This may happen in both parsimony and maximum-likelihood analyses, and even in small data sets without incongruence. [Bootstrap group support jackknife phylogenetic analysis resampling tree searches.] © The Author(s) 2014. Published by Oxford University Press, on behalf of the Society of Systematic Biologists. All rights reserved.

Rabinovich G.A.,CONICET | Rabinovich G.A.,University of Buenos Aires | van Kooyk Y.,VU University Amsterdam | Cobb B.A.,Case Western Reserve University
Annals of the New York Academy of Sciences | Year: 2012

Unlike their protein "roommates" and their nucleic acid "cousins," carbohydrates remain an enigmatic arm of biology. The central reason for the difficulty in fully understanding how carbohydrate structure and biological function are tied is the nontemplate nature of their synthesis and the resulting heterogeneity. The goal of this collection of expert reviews is to highlight what is known about how carbohydrates and their binding partners-the microbial (non-self), tumor (altered-self), and host (self)-cooperate within the immune system, while also identifying areas of opportunity to those willing to take up the challenge of understanding more about how carbohydrates influence immune responses. In the end, these reviews will serve as specific examples of how carbohydrates are as integral to biology as are proteins, nucleic acids, and lipids. Here, we attempt to summarize general concepts on glycans and glycan-binding proteins (mainly C-type lectins, siglecs, and galectins) and their contributions to the biology of immune responses in physiologic and pathologic settings. © 2012 New York Academy of Sciences.

Xu X.,CAS Institute of Vertebrate Paleontology and Paleoanthropology | Pol D.,CONICET
Journal of Systematic Palaeontology | Year: 2014

Archaeopteryx, which has often been considered the earliest avialan, is an iconic species, central to our understanding of bird origins. However, a recent parsimony-based phylogenetic study shifted its position from within Avialae, the group that contains modern birds, to Deinonychosauria, the sister-taxon to Avialae. Subsequently, probability-based methods were applied to the same dataset, restoring Archaeopteryx to basal Avialae, suggesting these methods should be used more often in palaeontological studies. Here we review two key issues: arguments recently advocated for the usefulness of probability-based methodologies in the phylogenetic reconstruction of basal birds and their close relatives, and support for different phylogenetic hypotheses. Our analysis demonstrates that Archaeopteryx represents a challenging taxon to place in the phylogenetic tree, but recent discoveries of derived theropods including basal avialans provide increased support for the deinonychosaurian affinities of Archaeopteryx. Most importantly, we underscore that methodological choices should be based on the adequacy of the assumptions for particular kinds of data rather than on the recovery of preferred or generally accepted topologies, and that certain probability methods should be interpreted with caution as they can grossly overestimate character support. © 2013 Natural History Museum.

Awruch C.A.,University of Tasmania | Awruch C.A.,CONICET
General and Comparative Endocrinology | Year: 2013

The class Chondrichthyes, that includes Elasmobranchii and Holocephali, is a diverse group of fish occupying a key position at the base of vertebrate evolution. Their evolutionary success is greatly attributed to their wide range of reproductive strategies controlled by different endocrine mechanics. As in other vertebrates, hormonal control of reproduction in chondrichthyans is mediated by the neuropeptide gonadotropin-releasing hormone (GnRH) that regulates the brain control of gonadal activity via a hypothalamus-pituitary-gonadal (HPG) axis. Chondrichthyans lack of a direct vascular supply from the hypothalamus to the zone of the pituitary where the gonadotropic activity resides, thus transport between these two zones likely occurs via the general circulation. In the brain of elasmobranchs, two groups of GnRH, GnRH-I and GnRH-II were identified, and the presence of two immunoreactive gonadotropins similar to the luteinising (LH) and follicle stimulating (FSH) hormones was identified in the pituitary. In holocephalans, only GnRH-II has been confirmed, and while gonadotropin activity has been found in the buccal pituitary lobe, the presence of gonadotropin receptors in the gonads remains unknowns. The diversity of reproductive strategies display by chondrichthyans makes it difficult to generalize the control of gametogenesis and steroidogenesis; however, some general patterns emerge. In both sexes, androgens and estrogens are the main steroids during gonadal growth; while progestins have maturational activity. Androgens also form the precursors for estrogen steroid production. Estrogens stimulate the hepatic synthesis of yolk and stimulate the development of different part of the reproductive tract in females. The role of other gonadal steroids may play in chondrichthyan reproduction remains largely unknown. Future work should concentrate in filling the gaps into the current knowledge of the HPG axis regulation, and the use of reproductive endocrinology as a non-lethal technique for management of chondrichthyan populations. © 2013 Elsevier Inc.

Hu N.,California Institute of Technology | Strobl-Mazzulla P.,CONICET | Sauka-Spengler T.,Weatherall Institute of Molecular Medicine | Bronner M.E.,California Institute of Technology
Genes and Development | Year: 2012

Here, we explore whether silencing via promoter DNA methylation plays a role in neural versus neural crest cell lineage decisions. We show that DNA methyltransferase3A (DNMT3A) promotes neural crest specification by directly mediating repression of neural genes like Sox2 and Sox3. DNMT3A is expressed in the neural plate border, and its knockdown causes ectopic Sox2 and Sox3 expression at the expense of neural crest markers. In vivo chromatin immunoprecipitation of neural folds demonstrates that DNMT3A specifically associates with CpG islands in the Sox2 and Sox3 promoter regions, resulting in their repression by methylation. Thus, DNMT3A functions as a molecular switch, repressing neural to favor neural crest cell fate. © 2012 by Cold Spring Harbor Laboratory Press.

Villordo S.M.,CONICET | Filomatori C.V.,CONICET | Sanchez-Vargas I.,Colorado State University | Blair C.D.,Colorado State University | Gamarnik A.V.,CONICET
PLoS Pathogens | Year: 2015

Many viral pathogens cycle between humans and insects. These viruses must have evolved strategies for rapid adaptation to different host environments. However, the mechanistic basis for the adaptation process remains poorly understood. To study the mosquito-human adaptation cycle, we examined changes in RNA structures of the dengue virus genome during host adaptation. Deep sequencing and RNA structure analysis, together with fitness evaluation, revealed a process of host specialization of RNA elements of the viral 3’UTR. Adaptation to mosquito or mammalian cells involved selection of different viral populations harvesting mutations in a single stem-loop structure. The host specialization of the identified RNA structure resulted in a significant viral fitness cost in the non-specialized host, posing a constraint during host switching. Sequence conservation analysis indicated that the identified host adaptable stem loop structure is duplicated in dengue and other mosquito-borne viruses. Interestingly, functional studies using recombinant viruses with single or double stem loops revealed that duplication of the RNA structure allows the virus to accommodate mutations beneficial in one host and deleterious in the other. Our findings reveal new concepts in adaptation of RNA viruses, in which host specialization of RNA structures results in high fitness in the adapted host, while RNA duplication confers robustness during host switching. © 2015 Villordo et al.

Strobl-Mazzulla P.H.,CONICET | Bronner M.E.,California Institute of Technology
Seminars in Cancer Biology | Year: 2012

The epithelial-to-mesenchymal transition (EMT) is an important event converting compact and ordered epithelial cells into migratory mesenchymal cells. Given the molecular and cellular similarities between pathological and developmental EMTs, studying this event during neural crest development offers and excellent in vivo model for understanding the mechanisms underlying this process. Here, we review new and old insight into neural crest EMT in search of commonalities with cancer progression that might aid in the design of specific therapeutic prevention. © 2012 Elsevier Ltd.

Simmons M.P.,Colorado State University | Goloboff P.A.,CONICET | Goloboff P.A.,Instituto Miguel Lillo
Molecular Phylogenetics and Evolution | Year: 2013

Empirical and simulated examples are used to demonstrate an artifact caused by undersampling optimal trees in data matrices that consist mostly or entirely of locally sampled (as opposed to globally, for most or all terminals) characters. The artifact is that unsupported clades consisting entirely of terminals scored for the same locally sampled partition may be resolved and assigned high resampling support-despite their being properly unsupported (i.e., not resolved in the strict consensus of all optimal trees). This artifact occurs despite application of random-addition sequences for stepwise terminal addition. The artifact is not necessarily obviated with thorough conventional branch swapping methods (even tree-bisection-reconnection) when just a single tree is held, as is sometimes implemented in parsimony bootstrap pseudoreplicates, and in every GARLI, PhyML, and RAxML pseudoreplicate and search for the most likely tree for the matrix as a whole. Hence GARLI, RAxML, and PhyML-based likelihood results require extra scrutiny, particularly when they provide high resolution and support for clades that are entirely unsupported by methods that perform more thorough searches, as in most parsimony analyses. © 2013 Elsevier Inc.

Hu N.,California Institute of Technology | Strobl-Mazzulla P.H.,CONICET | Bronner M.E.,California Institute of Technology
Developmental Biology | Year: 2014

The neural crest is a migratory and multipotent cell population that plays a crucial role in many aspects of embryonic development. In all vertebrate embryos, these cells emerge from the dorsal neural tube then migrate long distances to different regions of the body, where they contribute to formation of many cell types and structures. These include much of the peripheral nervous system, craniofacial skeleton, smooth muscle, and pigmentation of the skin. The best-studied regulatory events guiding neural crest development are mediated by transcription factors and signaling molecules. In recent years, however, growing evidence supports an important role for epigenetic regulation as an additional mechanism for controlling the timing and level of gene expression at different stages of neural crest development. Here, we summarize the process of neural crest formation, with focus on the role of epigenetic regulation in neural crest specification, migration, and differentiation as well as in neural crest related birth defects and diseases. © 2014 Elsevier Inc.

Kropff E.,Norwegian University of Science and Technology | Kropff E.,CONICET | Carmichael J.E.,Norwegian University of Science and Technology | Carmichael J.E.,Dartmouth College | And 2 more authors.
Nature | Year: 2015

Grid cells in the medial entorhinal cortex have spatial firing fields that repeat periodically in a hexagonal pattern. When animals move, activity is translated between grid cells in accordance with the animal's displacement in the environment. For this translation to occur, grid cells must have continuous access to information about instantaneous running speed. However, a powerful entorhinal speed signal has not been identified. Here we show that running speed is represented in the firing rate of a ubiquitous but functionally dedicated population of entorhinal neurons distinct from other cell populations of the local circuit, such as grid, head-direction and border cells. These 'speed cells' are characterized by a context-invariant positive, linear response to running speed, and share with grid cells a prospective bias of ∼50-80 ms. Our observations point to speed cells as a key component of the dynamic representation of self-location in the medial entorhinal cortex. © 2015 Macmillan Publishers Limited.

Buffone M.G.,CONICET | Wertheimer E.V.,University of Buenos Aires | Visconti P.E.,University of Massachusetts Amherst | Krapf D.,CONICET
Biochimica et Biophysica Acta - Molecular Basis of Disease | Year: 2014

Cyclic adenosine 3',5'-monophosphate (cAMP), the first second messenger to be described, plays a central role in cell signaling in a wide variety of cell types. Over the last decades, a wide body of literature addressed the different roles of cAMP in cell physiology, mainly in response to neurotransmitters and hormones. cAMP is synthesized by a wide variety of adenylyl cyclases that can generally be grouped in two types: transmembrane adenylyl cyclase and soluble adenylyl cyclases. In particular, several aspects of sperm physiology are regulated by cAMP produced by a single atypical adenylyl cyclase (Adcy10, aka sAC, SACY). The signature that identifies sAC among other ACs, is their direct stimulation by bicarbonate. The essential nature of cAMP in sperm function has been demonstrated using gain of function as well as loss of function approaches. This review unifies state of the art knowledge of the role of cAMP and those enzymes involved in cAMP signaling pathways required for the acquisition of fertilizing capacity of mammalian sperm. This article is part of a Special Issue entitled: The role of soluble adenylyl cyclase in health and disease. © 2014 Elsevier B.V.

News Article | September 29, 2016
Site: www.rdmag.com

Humans may have occupied the Southern Cone 14,000 years ago, according to a study published September 28, 2016 in the open-access journal PLOS ONE by Gustavo Politis from CONICET and the Universidad Nacional del Centro de la Provincia de Buenos Aires, Argentina and colleagues. The authors of the present study sought to date the earliest human occupation of the Arroyo Seco 2, a rich archaeological site in the Southern Cone, the southern tip of South America. At Arroyo Seco 2, researchers excavated ancient tools, bone remains from a variety of extinct species, and broken animal bones containing fractures caused by human tools. They used radiocarbon dating techniques to determine the age of the mammal bones, and applied microscopic analysis to the specimens. The researchers found limb bones from extinct mammals at the site, which may indicate human activities of depositing and transporting animal carcasses for consumption at a temporary camp. They found that the bones of some mammal species were concentrated in a specific area of the site, which could indicate specific areas of butchering activities. Microscopic examination also revealed that some bones contained fractures most likely caused by stone tools. Finally, the material remains found at the site were dated between 14,064 and 13,068 years ago, and thus the authors hypothesize that the Arroyo Seco 2 site may have been occupied by humans during that time. This timeline, along with other South American sites, indicates that humans may have arrived at the Southern Cone prior to the Clovis people, but after the onset of the Last Glacial Maximum, or last glacial period which took place 19,000-20,000 years ago. While the characteristics of some of these archaeological materials could be explained without human intervention, the combination of evidence strongly suggests human involvement. Humans' arrival into the Southern Cone 14,000 years ago may represent the last step in the expansion of Homo sapiens throughout the world and the final continental colonization.

Vignolo L.D.,CONICET | Milone D.H.,CONICET | Scharcanski J.,Federal University of Rio Grande do Sul
Expert Systems with Applications | Year: 2013

Feature selection is a key issue in pattern recognition, specially when prior knowledge of the most discriminant features is not available. Moreover, in order to perform the classification task with reduced complexity and acceptable performance, usually features that are irrelevant, redundant, or noisy are excluded from the problem representation. This work presents a multi-objective wrapper, based on genetic algorithms, to select the most relevant set of features for face recognition tasks. The proposed strategy explores the space of multiple feasible selections in order to minimize the cardinality of the feature subset, and at the same time to maximize its discriminative capacity. Experimental results show that, in comparison with other state-of-the-art approaches, the proposed approach allows to improve the classification performance, while reducing the representation dimensionality. © 2013 Elsevier Ltd. All rights reserved.

Hader D.-P.,Neue Str. 9 | Helbling E.W.,CONICET | Williamson C.E.,Miami University Ohio | Worrest R.C.,Columbia University
Photochemical and Photobiological Sciences | Year: 2011

The health of freshwater and marine ecosystems is critical to life on Earth. The impact of solar UV-B radiation is one potential stress factor that can have a negative impact on the health of certain species within these ecosystems. Although there is a paucity of data and information regarding the effect of UV-B radiation on total ecosystem structure and function, several recent studies have addressed the effects on various species within each trophic level. Climate change, acid deposition, and changes in other anthropogenic stressors such as pollutants alter UV exposure levels in inland and coastal marine waters. These factors potentially have important consequences for a variety of aquatic organisms including waterborne human pathogens. Recent results have demonstrated the negative impacts of exposure to UV-B radiation on primary producers, including effects on cyanobacteria, phytoplankton, macroalgae and aquatic plants. UV-B radiation is an environmental stressor for many aquatic consumers, including zooplankton, crustaceans, amphibians, fish, and corals. Many aquatic producers and consumers rely on avoidance strategies, repair mechanisms and the synthesis of UV-absorbing substances for protection. However, there has been relatively little information generated regarding the impact of solar UV-B radiation on species composition within natural ecosystems or on the interaction of organisms between trophic levels within those ecosystems. There remains the question as to whether a decrease in population size of the more sensitive primary producers would be compensated for by an increase in the population size of more tolerant species, and therefore whether there would be a net negative impact on the absorption of atmospheric carbon dioxide by these ecosystems. Another question is whether there would be a significant impact on the quantity and quality of nutrients cycling through the food web, including the generation of food proteins for humans. Interactive effects of UV radiation with changes in other stressors, including climate change and pollutants, are likely to be particularly important. © 2011 The Royal Society of Chemistry and Owner Societies.

Harguinteguy C.A.,CONICET | Schreiber R.,Helmholtz Center for Environmental Research | Pignata M.L.,CONICET
Ecological Indicators | Year: 2013

The aim of the present study was to assess the temporal variation of the heavy metal content (Co, Cu, Fe, Mn, Ni, Pb, and Zn) in surface water and sediments in relation to agricultural practices in the Xanaes River (Córdoba, Argentina). A second objective was to analyze possible relationships between the input of heavy metals on surface water and sediment, heavy metal accumulation and physiological changes in the aquatic plant Myriophyllum aquaticum. Samples were taken from the river at two contrasting sites (between April 2010 and August 2010): (1) a pristine area (mountain site), and (2) an area with intensive agricultural activity located at 60 km down river (agricultural site). The total concentration of heavy metals in surface water was higher in samples collected at the agricultural site but in sediments only the Mn concentration was higher than at the mountain site. The Fe and Mn concentrations in surface water at the agricultural site exceeded the recommended values for Argentinean Legislation of 300 μg L-1 for Fe and 100 μg L-1 for Mn. The accumulations of Zn and Mn in M. aquaticum were higher at the agricultural site and more elevated than the Zn and Mn concentrations in sediments at the same sites and sampling times. At the agricultural site, temporal variations of Cu, Fe and Zn were relatively similar for plants and water column, but the levels of the metals in plants were displaced over time. These results suggest that the levels of pollutants in the river came in pulses from the riverbank. These results show the potential use of M. aquaticum as a suitable accumulation biomonitor at the early stages of heavy metal pollution in rivers. © 2012 Elsevier Ltd.

Bussi I.L.,National University of Quilmes | Levin G.,CONICET | Golombek D.A.,National University of Quilmes | Agostino P.V.,National University of Quilmes
European Journal of Neuroscience | Year: 2014

Duration discrimination within the seconds-to-minutes range, known as interval timing, involves the interaction of cortico-striatal circuits via dopaminergic-glutamatergic pathways. Besides interval timing, most (if not all) organisms exhibit circadian rhythms in physiological, metabolic and behavioral functions with periods close to 24h. We have previously reported that both circadian disruption and desynchronization impaired interval timing in mice. In this work we studied the involvement of dopamine (DA) signaling in the interaction between circadian and interval timing. We report that daily injections of levodopa improved timing performance in the peak-interval procedure in C57BL/6 mice with circadian disruptions, suggesting that a daily increase of DA is necessary for an accurate performance in the timing task. Moreover, striatal DA levels measured by reverse-phase high-pressure liquid chromatography indicated a daily rhythm under light/dark conditions. This daily variation was affected by inducing circadian disruption under constant light (LL). We also demonstrated a daily oscillation in tyrosine hydroxylase levels, DA turnover (3,4-dihydroxyphenylacetic acid/DA levels), and both mRNA and protein levels of the circadian component Period2 (Per2) in the striatum and substantia nigra, two brain areas relevant for interval timing. None of these oscillations persisted under LL conditions. We suggest that the lack of DA rhythmicity in the striatum under LL - probably regulated by Per2 - could be responsible for impaired performance in the timing task. Our findings add further support to the notion that circadian and interval timing share some common processes, interacting at the level of the dopaminergic system. © 2014 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.

Inchaurrondo N.,CONICET | Cechini J.,CONICET | Font J.,Rovira i Virgili University | Haure P.,CONICET
Applied Catalysis B: Environmental | Year: 2012

The performance of a commercial CuO/alumina catalyst used in the catalytic wet peroxide oxidation (CWPO) of 1. g/l phenol solutions is investigated in a batch reactor. The effect of temperature, catalyst load, hydrogen peroxide concentration and dosage strategies on phenol mineralization, hydrogen peroxide consumption efficiencies and catalyst stability was studied. Experiments were performed at 298, 323 and 343. K, using catalyst loads of 1. g/l or 25. g/l and concentrations of hydrogen peroxide 1.3, 2.6 and 3.9 times the stoichiometric requirement added at once or in distributed doses. The critical goal of the CWPO in terms of Process Intensification is to achieve total phenol mineralization working at optimal hydrogen peroxide consumption efficiencies while retaining catalyst stability. The present work highlights the complexity of this objective and shows viable working alternatives.Results indicate that high temperatures and concentrations of catalyst and hydrogen peroxide (added at once) can be employed when fast mineralization and high pH values are required in order to prevent catalyst leaching, although oxidant consumption efficiencies are then low. However, simultaneous high mineralization and hydrogen peroxide consumption efficiencies are obtained with a proper oxidant dosage strategy at high temperature, using high catalyst load. Then, hydrogen peroxide degradation into non-oxidising (parasitic) species is minimized with final TOC conversions close to 90%. The drawback of this strategy is that the rate of reaction is lower because of the limited amount of oxidant available. © 2011 Elsevier B.V.

Cochrane K.L.,Food and Agriculture Organization of the United Nations | Andrew N.L.,Worldfish Center | Parma A.M.,CONICET
Fish and Fisheries | Year: 2011

The social and economic importance of small-scale fisheries is frequently under-valued, and they are rarely effectively managed. There is now growing consensus on how these fisheries could be managed for sustainability and to minimize the risks of crossing undesirable thresholds. Using a concept developed in health care, these approaches have been referred to as primary fisheries management. By encouraging the use of best-available information in a precautionary way, the approaches will facilitate sustainable use and should therefore be encouraged, but they accept high scientific and implementation uncertainties as unavoidable because of limited management and enforcement resources and capacity. It is important to recognize that this limitation will result in social costs, because application of a precautionary approach in the face of high uncertainties will require forgoing potential sustainable benefits. Acceptance of primary fisheries management as a final and sufficient goal could therefore add a further constraint on the possibility of fishing communities escaping the poverty trap. Primary fisheries management should be seen as a first and minimum target for fisheries where there is currently no or inadequate management, but the longer-term goal should still be well informed and adaptive management that strives for optimal benefits, referred to here as tertiary management. © 2010 Blackwell Publishing Ltd.

Holanda E.C.,Federal University of Rio Grande do Sul | Ferrero B.S.,CONICET
Journal of Mammalian Evolution | Year: 2013

The record of the genus Tapirus in South America is associated with the faunistic events of the Great American Biotic Interchange (GABI). The taxon is considered an immigrant of Holarctic origin. Although remains are scarce and incomplete during the Pleistocene, an analysis of these materials allowed us to consider valid seven fossil species: Tapirus tarijensis, T. cristatellus, T. greslebini, T. rioplatensis, T. oliverasi, T. mesopotamicus, and T. rondoniensis. A phylogenetic analysis was carried out in order to elucidate the relationships of the American fossil and extant species. Our result is consistent with a paraphyletic hypothesis for South American tapirs and suggests that a second dispersal event would have occurred from South America to North America, of a form closely related to T. cristatellus, resulting in the derived forms of North America. © 2012 Springer Science+Business Media, LLC.

Sanguinetti A.,University of Buenos Aires | Sanguinetti A.,CONICET | Singer R.B.,Federal University of Rio Grande do Sul
Biological Conservation | Year: 2014

Most non-autogamous orchids rely on either a single, or on a small number of pollinators to set fruit. The nectar-rewarding orchid Brachystele unilateralis and the nectarless and deceit-pollinated Chloraea virescens are restricted to the Southern Andes, where a single native and endemic bumblebee (Bombus dahlbomii) occured until the introduction of honeybees and highly invasive European bumblebees. Here, we describe the floral features, breeding system, pollinator activity and fruiting success of these orchid species. Both are self-compatible but pollinator-dependent, i.e., unable to set fruit and seed in the absence of pollinators. Field observations revealed that most of their current reproductive success is due to the introduced Bombus terrestris, Bombus ruderatus and Apis mellifera bees. The only native pollinator recorded was B. dahlbomii, but this bee was rarely observed due to its steady decline since the introduction of the alien Bombus species. The observed natural fruiting success per inflorescence in both studied species proved to be remarkably high by orchid standards: 83% and 66%, respectively. These results suggest that sexual reproduction in these orchids is not necessarily threatened by the decline of their native pollinator since pollination is successfully achieved by introduced bees. This provides a plausible better outlook for these and other regional, bumblebee-pollinated orchids and raises caution on eventual conservation policies involving the management of these introduced bee species. To our knowledge, this is the first report of native orchid pollinators being effectively replaced by invasive bumblebees and, furthermore, the first description of the pollination biology of a species of Brachystele. © 2014 Elsevier Ltd.

Arruvito L.,Hospital Of Clinicas Jose Of San Martin | Raiden S.,Hospital General Of Ninos Pedro Of Elizalde | Geffner J.,CONICET
Current Opinion in Infectious Diseases | Year: 2015

Purpose of review Respiratory syncytial virus (RSV) infection is the leading cause of bronchiolitis and hospitalization in young infants and causes 100000-200000 deaths annually. There is still no licensed vaccine against RSV infection and the therapeutic options are mainly supportive. Despite almost six decades of research, important knowledge gaps remain with respect to the characterization of immune mechanisms responsible for protection and pathogenesis, as well as to the identification of risk factors that predict the severity of infection. Recent findings Observations made in mouse models and young children suggest that the early innate immune response plays a major role in the pathogenesis of bronchiolitis due to RSV infection. Recent studies have improved our understanding of the role of the adaptive immune response mediated by TH1, TH2, TH17, regulatory T cells, and CD8 + T cells in the pathogenesis and resolution of RSV infection. Moreover, investigations performed in the last years have made important contributions to our knowledge of the immune response in young children, the principal risk group for severe disease. Summary A comprehensive understanding of how the protective and deleterious immune response during the course of RSV infection is induced in young children remains a challenge over the coming years. © 2015 Wolters Kluwer Health, Inc. All rights reserved.

Massaferro J.,CONICET | Larocque-Tobler I.,LimnoPaleoServ
Ecological Indicators | Year: 2013

In the Southern Hemisphere, the lack of quantitative temperature records hampers the understanding of climate change since the Last Glaciation and refrains the comparison with the Northern Hemisphere records. To provide quantitative data, a 63-lake chironomid transfer functions was developed in Patagonia. Mean annual air temperature (MAT) was one of the most important factors explaining the distribution of chironomids while precipitation did not have any significant relationship with chironomid assemblages. The MAT model had a r2 of 0.64, a RMSE of 0.83 and a maximum bias of 1.81 °C, comparable to other transfer functions of this size. This model was applied to the Lake Potrok Aike (PTA) chironomid records which consisted of only four taxa (Phaenopsectra, Cricotopus, Smittia and Polypedilum). The chironomid-inferred air temperatures were colder-than-the-average (10.8°C) during the Lateglacial with the coldest temperatures (9°C in average) during the Antarctic Cold Reversal (ACR). Between ca. 8000 and 3500 cal. years BP, the chironomid-inferred air temperatures were warmer-than-the-average with a decreasing trend. From ca. 3500 cal. years BP to the present, the chironomid-inferred temperatures oscillated around the average. The difference between the chironomid-inferred air temperature in the surface sample and the climate normal (1961-1990) was 0.6°C, suggesting that chironomids are sensitive enough to quantitatively reconstruct MAT at PTA. The general pattern of temperature changes reconstructed by the PTA chironomid record corresponded well to other quantitative records in the Southern Hemisphere. The results presented here show that investing in the development of chironomid transfer functions for quantitative climate research in the Southern Hemisphere is valuable. © 2012 Elsevier Ltd. All rights reserved.

Rohrmann R.D.,CONICET | Althaus L.G.,CONICET | Kepler S.O.,Federal University of Rio Grande do Sul
Monthly Notices of the Royal Astronomical Society | Year: 2011

Kowalski & Saumon identified the missing absorption mechanism in the observed spectra of cool white dwarf stars as the Lyman α red wing formed by the collisions between atomic and molecular hydrogen and successfully explained entire spectra of many cool DA-type white dwarfs. Owing to the important astrophysical implications of this issue, we present here an independent assessment of the process. For this purpose, we compute free-free quasi-molecular absorption in Lyman α due to collisions with H and H2 within the one-perturber, quasi-static approximation. Line cross-sections are obtained using theoretical molecular potentials to describe the interaction between the radiating atom and the perturber. The variation in the electric dipole transition moment with the interparticle distance is also considered. Six and two allowed electric dipole transitions due to H-H and H-H2 collisions, respectively, are taken into account. The new theoretical Lyman α line profiles are then incorporated in our stellar atmosphere program for the computation of synthetic spectra and colours of DA-type white dwarfs. Illustrative model atmospheres and spectral energy distributions are computed, which show that Lyman α broadening by atoms and molecules has a significant effect on the white dwarf atmosphere models. The inclusion of this collision-induced opacity significantly reddens spectral energy distributions and affects the broad-band colour indices for model atmospheres with Teff < 5000K. These results confirm those previously obtained by Kowalski & Saumon. Our study points out the need for reliable evaluations of H3 potential energy surfaces covering a large region of nuclear configurations, in order to obtain a better description of H-H2 collisions and a more accurate evaluation of their influence on the spectrum of cool white dwarfs. © 2010 The Authors Monthly Notices of the Royal Astronomical Society © 2010 RAS.

Inis Biotech Llc, Conicet and National University of Quilmes | Date: 2013-12-26

Antimicrobial peptides such as, for example, the peptides shown in SEQ ID No 1, SEQ ID No 2, SEQ ID No 3, SEQ ID No 4 or SEQ ID No 5. The peptides have activity against Gram positive bacteria and against Gram negative bacteria. A bactericidal composition is also provided, which may comprise an amount between 0.5 g/mL and 1024 g/mL of the peptides; and excipients.

Ypf Sociedad Anonima and Conicet | Date: 2014-06-11

A method and apparatus is provided for detecting and identifying faults in a process having a set of sensors, each of which produces an associated sensor output signal. The method and apparatus extracts the qualitative trend of each variable after detecting an abnormal situation. The set of variable trends constitutes the fault signature which can be compared to a previously generated signature database.

Flores F.G.,National University of Cordoba | Flores F.G.,CONICET
Computer Methods in Applied Mechanics and Engineering | Year: 2013

In this paper a triangular prism solid element for the analysis of thin/thick shells undergoing large elastic-plastic strains is developed. The element is based on a total Lagrangian formulation and uses as strain measure the logarithm of the right stretch tensor (U) obtained from a modified right Cauchy-Green deformation tensor (C̄). Three are the introduced modifications: (a) a classical assumed strain approach for transverse shear strains (b) an assumed strain approach for the in-plane components using information from neighbor elements and (c) an averaging of the volumetric strain over the element. The objective is to use this type of elements for the simulation of shells avoiding transverse shear locking, improving the membrane behavior of the in-plane triangle and to handle quasi-incompressible materials or materials with isochoric plastic flow. Several examples are presented that show the transverse-shear locking free behavior, the importance of the improvement in the membrane approach and the wide possibilities of the introduced element for the analysis of shell structures for both geometric and material non-linear behavior. © 2012 Elsevier B.V.

The main aim of the present work is to synthesize the information obtained from our dissections of the pectoral and forelimb muscles of representative members of the major extant taxa of limbed amphibians and reptiles and from our review of the literature, in order to provide an account of the comparative anatomy, homologies and evolution of these muscles in the Tetrapoda. The pectoral and forelimb musculature of all these major taxa conform to a general pattern that seems to have been acquired very early in the evolutionary history of tetrapods. Although some muscles are missing in certain taxa, and a clear departure from this general pattern is obviously present in derived groups such as birds, the same overall configuration is easily distinguishable in these taxa. Among the most notable anatomical differences between the groups, one that seems to have relevant evolutionary and functional implications, concerns the distal insertion points of the forearm musculature. In tetrapods, the muscles of the radial and ulnar complexes of the forearm are pleisomorphically mainly inserted onto the radius/ulna or onto the more proximal carpal bones, but in mammals some of these muscles insert more distally onto bones such as the metacarpals. Interestingly, a similar trend towards a more distal insertion of these muscles is also found in some non-mammalian tetrapod taxa, such as some anurans (e.g. Phyllomedusa). This may be correlated with the acquisition of more subtle digital movement abilities in these latter taxa. © 2010 The Authors. Journal of Anatomy © 2010 Anatomical Society of Great Britain and Ireland.

Goicoechea H.C.,National University of Santa | Olivieri A.C.,CONICET | Tauler R.,CSIC - Institute of Environmental Assessment And Water Research
Analyst | Year: 2010

Correlation constrained multivariate curve resolution-alternating least-squares is shown to be a feasible method for processing first-order instrumental data and achieve analyte quantitation in the presence of unexpected interferences. Both for simulated and experimental data sets, the proposed method could correctly retrieve the analyte and interference spectral profiles and perform accurate estimations of analyte concentrations in test samples. Since no information concerning the interferences was present in calibration samples, the proposed multivariate calibration approach including the correlation constraint facilitates the achievement of the so-called second-order advantage for the analyte of interest, which is known to be present for more complex higher-order richer instrumental data. The proposed method is tested using a simulated data set and two experimental data systems, one for the determination of ascorbic acid in powder juices using UV-visible absorption spectral data, and another for the determination of tetracycline in serum samples using fluorescence emission spectroscopy. © 2010 The Royal Society of Chemistry.

Cicuttin G.,Institute Zoonosis Luis Pasteur | Nava S.,CONICET
Memorias do Instituto Oswaldo Cruz | Year: 2013

Specimens of the hard tick Amblyomma triste were found infected with Rickettsia parkeri in an area of Argentina (General Lavalle, Buenos Aires Province) where cases of human illness attributed to this microorganism have been reported. Molecular detection of R. parkeri was based on polymerase chain reactions that amplify a ca. 400-bp fragment of the 23S-5S intergenic spacer and a ca. 500-bp fragment of the gene encoding a 190-kDa outer membrane protein. Three (6.97%) of 43 A. triste ticks were determined to be positive for R. parkeri. These results provide strong evidence that A. triste is the vector of R. parkeri in the study area. The findings of this work have epidemiological relevance because human parasitism by A. triste ticks has been frequently recorded in some riparian areas of Argentina and Uruguay and new cases of R. parkeri rickettsiosis might arise in the South American localities where humans are exposed to the bites of this tick species.

Solomon S.,New York Stem Cell Foundation | Pitossi F.,CONICET | Rao M.S.,Stem Cell Therapeutics
Stem Cell Reviews and Reports | Year: 2015

The discovery of induced pluripotent stem cells (iPSCs) and concurrent development of protocols for their cell-type specific differentiation have revolutionized studies of diseases and raised the possibility that personalized medicine may be achievable. Realizing the full potential of iPSC will require addressing the challenges inherent in obtaining appropriate cells for millions of individuals while meeting the regulatory requirements of delivering therapy and keeping costs affordable. Critical to making PSC based cell therapy widely accessible is determining which mode of cell collection, storage and distribution, will work. In this manuscript we suggest that moderate sized bank where a diverse set of lines carrying different combinations of commonly present HLA alleles are banked and differentiated cells are made available to matched recipients as need dictates may be a solution. We discuss the issues related to developing such a bank and how it could be constructed and propose a bank of selected HLA phenotypes from carefully screened healthy individuals as a solution to delivering personalized medicine. © 2014, The Author(s).

Dambolena J.S.,CONICET | Zygadlo J.A.,CONICET | Rubinstein H.R.,National University of Cordoba
International Journal of Food Microbiology | Year: 2011

Fumonisin B 1 (FB 1) is a Fusarium mycotoxin that has received considerable attention from food regulatory agencies, since it shows immunotoxic, neurotoxic, hepatotoxic, nephrotoxic and carcinogenic properties in animals. Although several publications have reported that some natural phenolic compounds can cause a reduction in mycotoxin production, little is known about the molecular properties related to their antitoxigenic activities. The objective of this work was to evaluate which of these molecular properties are important in antifumonisin activity, with this being the first structure-activity relationship study concerning the antimyctoxigenic activity of natural phenolic compounds. The results of the experimental determination of the FB 1 inhibition capacity for ten natural phenolic compounds revealed thymol, carvacrol, and isoeugenol followed by eugenol to be the most active antifumonisin compounds. Lipophilicity, molar refractivity and saturated area were demonstrated to be the molecular properties or descriptors which best explained the antifumonisin activity of these phenolic compounds. A mathematical expression, obtained by QSAR analysis, was able to predict the antifumonisin activity of other structurally related molecules. These findings could provide an important contribution in the search for new compounds with antifumonisin activity. © 2010 Elsevier B.V.

Arrossi S.,CONICET | Thouyaret L.,Instituto Nacional del Cancer Argentina | Herrero R.,International Agency for Research on Cancer | Campanera A.,Ministerio de Salud de la Provincia de Jujuy | And 5 more authors.
The Lancet Global Health | Year: 2015

Background: Control of cervical cancer in developing countries has been hampered by a failure to achieve high screening uptake. HPV DNA self-collection could increase screening coverage, but implementation of this technology is difficult in countries of middle and low income. We investigated whether offering HPV DNA self-collection during routine home visits by community health workers could increase cervical screening. Methods: We did a population-based cluster-randomised trial in the province of Jujuy, Argentina, between July 1, 2012, and Dec 31, 2012. Community health workers were eligible for the study if they scored highly on a performance score, and women aged 30 years or older were eligible for enrolment by the community health worker. 200 community health workers were randomly allocated in a 1:1 ratio to either the intervention group (offered women the chance to self-collect a sample for cervical screening during a home visit) or the control group (advised women to attend a health clinic for cervical screening). The primary outcome was screening uptake, measured as the proportion of women having any HPV screening test within 6 months of the community health worker visit. Analysis was by intention to treat. This trial is registered with ClinicalTrials.gov, number NCT02095561. Findings: 100 community health workers were randomly allocated to the intervention group and 100 were assigned to the control group; nine did not take part. 191 participating community health workers (94 in the intervention group and 97 in the control group) initially contacted 7650 women; of 3632 women contacted by community health workers in the intervention group, 3049 agreed to participate; of 4018 women contacted by community health workers in the control group, 2964 agreed to participate. 2618 (86%) of 3049 women in the intervention group had any HPV test within 6 months of the community health worker visit, compared with 599 (20%) of 2964 in the control group (risk ratio 4·02, 95% CI 3·44-4·71). Interpretation: Offering self-collection of samples for HPV testing by community health workers during home visits resulted in a four-fold increase in screening uptake, showing that this strategy is effective to improve cervical screening coverage. This intervention reduces women's barriers to screening and results in a substantial and rapid increase in coverage. Our findings suggest that HPV testing could be extended throughout Argentina and in other countries to increase cervical screening coverage. Funding: Instituto Nacional del Cáncer (Argentina). © 2015 Arrossi et al. Open Access article distributed under the terms of CC BY-NC-ND.

Visentin A.,National University of Rio Cuarto | Cismondi M.,National University of Cordoba | Maestri D.,CONICET
Innovative Food Science and Emerging Technologies | Year: 2011

Supercritical fluid antisolvent fractionation was used to obtain antioxidant compounds, mainly carnosic acid (CA), from high viscous oleoresins derived from dried rosemary leaves (Rosmarinus officinalis) extracted with ethanol. Due to the high viscosity of the starting material, which may hinder the mass transfer between the phases, a special nozzle was designed to blend the SCCO2 stream with the high viscous oleoresin. Experiments were conducted at 50 °C and six different pressures in the first separation vessel, ranging from 150 to 400 bar; the best separation was achieved at 300 bar. As a result of the oleoresin two-stage fractionation, the starting material was separated in two fractions. The first one was an insoluble dark green powder, with low concentration of CA (< 5 g/100 g extract). The other fraction was an orange colored resinous extract, very soluble in SCCO 2, with a high concentration of CA (33 g/100 g extract at 300 bar). The antioxidant effect of this extract was higher to that of BHT when added to soybean oil. Industrial relevance: The present study adds a possibility for the purification of carnosic acid from rosemary by using SCCO2 antisolvent fractionation. Since the starting material employed (oleoresin) is a fluid phase, the process might be carried out in a continuous or semi-continuous way instead of discontinuous as it should be done if the starting material were a solid (leaves). This feature makes the procedure very promising toward its application at the industrial scale. © 2011 Elsevier Ltd. All rights reserved.

Zwick A.,National University of Cordoba | Osenda O.,CONICET
Journal of Physics A: Mathematical and Theoretical | Year: 2011

One spin excitation states are involved in the transmission of quantum states and entanglement through a quantum spin chain, the localization properties of these states are crucial to achieve the transfer of information from one extreme of the chain to the other. We investigate the bipartite entanglement and localization of the one excitation states in a quantum XX chain with one impurity. The bipartite entanglement is obtained using the concurrence and the localization is analyzed using the inverse participation ratio (IPR). Changing the strength of the exchange coupling of the impurity allows us to control the number of localized or extended states. The analysis of the IPR allows us to identify scenarios where the transmission of quantum states or entanglement can be achieved with a high degree of fidelity. In particular, we identify a regime where the transmission of quantum states between the extremes of the chain is executed in a short transmission time ∼ N/2, where N is the number of spins in the chain, and with a large fidelity. © 2011 IOP Publishing Ltd.

de Abelleyra D.,Instituto Nacional de Tecnologia Agropecuaria | Veron S.R.,Instituto Nacional de Tecnologia Agropecuaria | Veron S.R.,CONICET
Remote Sensing of Environment | Year: 2014

Realizing the full benefits of MODIS' temporal resolution requires, among others, the correction of the directional effect (i.e. the combined impact of the variation of the measurement geometry and of the observed land surface upon the registered radiant flux). While different BRDF methods have been proposed to address this effect, its performance has been evaluated at coarse spatial resolutions making it difficult to assess its applicability to, for example, crop monitoring. Here we test 2 approaches based on two different assumptions: the Classic approach that relies on the hypothesis of stable target and a recent Alternative that is based on the idea that despite reflectance magnitude may change rapidly, the BRDF shape varies slowly in time. Additionally, we segmented the growing season into different numbers of periods for the BRDF correction (a single period along the growing season, 3 periods based in phenology and 9-12 periods of fixed 16-days). The resulting 6 methods were compared over annual crops (wheat, maize and soybean) at 250. m spatial resolution from a site located in the Argentine Pampas. We used MOD and MYD 09 GQ and GA as inputs and compared the corrected daily red and infrared reflectances and the NDVI time series against the filtered benchmark (input time series with quality filters applied) by means of the high frequency variability (i.e. noise). We also tested whether corrected time series were better correlated with soybean PAR interception and biomass. Our results showed that methods' performance was more explained by the number of periods than by the approach (Classic or Alternative). Single period methods decreased noise by 52%, 55% and 4% for red, infrared and NDVI time series. The use of 3 periods improved the correction performance to 63, 64 and 24% for red, infrared and NVDI time series respectively, while the highest reductions (65, 68 and 32% for red, infrared and NVDI) were found with 16-day intervals (9-12 periods) considering a magnitude inversion process. Wheat displayed the lowest noise reduction compared to the other crops. BRDF parameters obtained from different methods were associated to crop structure, suggesting that they have biophysical meaning. The decrease in noise obtained with correction methods was translated into a better assessment of the fraction of intercepted PAR and biomass. These promising results suggest the possibility of extensive field crop monitoring at an unprecedented temporal resolution. © 2013 Elsevier Inc.

Otranto S.,CONICET | Olson R.E.,Missouri University of Science and Technology
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2011

X-ray emission originating in charge-exchange collisions between Ar18 + and neutral argon is studied at impact energies of 5-4000 eV/amu by means of the classical trajectory Monte Carlo method (CTMC). Line emission and charge-exchange cross sections obtained from different CTMC versions based on the one-active electron approximation are contrasted among themselves and against the results obtained by means of a three-active electron code that lets us infer the role of multiple electron capture. The present results are compared to the recent experimental data available from the EBIT groups operating at Livermore, NIST, and Berlin. We were not able to reconcile the major difference in x-ray emission cross sections obtained from in situ measurements made in EBIT, versus those made in an exterior, field-free collision chamber using ions extracted from the EBIT. Our calculations support the extracted beam results. © 2011 American Physical Society.

Tang Y.,University of California at San Diego | Bringa E.M.,CONICET | Remington B.A.,Lawrence Livermore National Laboratory | Meyers M.A.,University of California at San Diego
Acta Materialia | Year: 2011

The growth and collapse of nanoscale voids are investigated for tantalum (a model body-centered cubic metal) under different stress states and strain rates by molecular dynamics (MD). Three principal mechanisms of deformation are identified and quantitatively evaluated: (i) shear loop emission and subsequent expansion from the surface of the void; (ii) cooperative shear loop emission from slip planes that are parallel to the same 〈1 1 1〉 slip direction and their combination, forming prismatic loops; (iii) twinning starting at the void surface. The generation and evolution of these defects are found to be functions of stress state and strain rate. Dislocations are found to propagate preferably on {1 1 0} and {1 1 2} planes, with Burgers vectors 1/2 〈1 1 1〉. The dislocation shear loops generated expand in a crystallographic manner, and in hydrostatic tension and compression generate prismatic loops that detach from the void. In uniaxial tensile strain along [1 0 0], the extremities of the shear loops remain attached to the void surface, a requisite for void growth. In uniaxial compressive strain, the extremities of the shear loops can also detach from the void surface. The difference in defect evolution is explained by the equal resolved shear stress in the hydrostatic loading case, in contrast with uniaxial strain loading. Nanotwins form preferably upon both uniaxial tensile strain and hydrostatic stress (in tension) and there is a slip-to-twinning transition as the strain rate exceeds 108 s -1. A simplified constitutive description is presented which explains the preponderance of twinning over slip in tension beyond a critical strain rate. The formation of both dislocations and twins is confirmed through laser compression experiments, which provide strain rates (∼108 s -1) comparable to MD. The dislocation velocities are determined by tracking the edge component of the expanding loops and are found to be subsonic even at extremely high stress and strain rates: 680 m s-1 for 10 8 s-1 and 1020 m s-1 for 109 s -1. © 2010 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

De Lucio O.G.,National Autonomous University of Mexico | Otranto S.,CONICET | Olson R.E.,Missouri University of Science and Technology | Dubois R.D.,Missouri University of Science and Technology
Physical Review Letters | Year: 2010

Triply differential single ionization of Ar by 200 eV positron and electron impact is measured and calculated. For an unequivocal test of kinematic differences, fully differential ejected electron angular distributions are measured using the same experimental apparatus and conditions for both positron and electron impact. The binary/recoil intensity ratios are shown to significantly differ for the two projectiles. These data are used to test theoretical calculations. © 2010 The American Physical Society.

Kovalsky M.G.,CONICET | Hnilo A.A.,CONICET | Tredicce J.R.,CNRS Non-Linear Institute of Nice
Optics Letters | Year: 2011

We report experimental and theoretical evidence of the existence of extreme value events in the form of scarce and randomly emerging giant pulses in the femtosecond (self-pulsing or Kerr-lens mode-locked) Ti:sapphire laser. This laser displays complex dynamical behavior, including deterministic chaos, in two different regimes. The extreme value pulses are observed in the chaotic state of only one of these two regimes. The observations agree with the predictions of a well-tested theoretical model that does not include noise or self-Q-switching into its framework. This implies that, in this laser, the extreme effects have a nontrivial dynamical origin. The Ti:sapphire laser is hence revealed as a new and convenient system for the study of these effects. © 2011 Optical Society of America.

Pozner R.,CONICET | Zanotti C.,CONICET | Johnson L.A.,Brigham Young University
American Journal of Botany | Year: 2012

Premise of the study: Phylogenies based on molecular data are revealing that generalizations about complex morphological structures often obscure variation and developmental patterns important for understanding the evolution of forms, as is the case for inflorescence morphology within the well-supported MGCA clade (Menyanthaceae + Goodeniaceae + Calyceraceae + Asteraceae). While the basal families share a basic thyrsic/thyrsoid structure of their inflorescences, Asteraceae possesses a capitulum that is widely interpreted as a racemose, condensed inflorescence. Elucidating the poorly known inflorescence structure of Calyceraceae, sister to Asteraceae, should help clarify how the Asteraceae capitulum evolved from thyrsic/thyrsoid inflorescences. • Methods: The early development and structure of the inflorescence of eight species (five genera) of Calyceraceae were studied by SEM, and patterns of evolutionary change were interpreted via phylogenetic character mapping. • Key results: The basic inflorescence structure of Calyceraceae is a cephalioid (a very condensed botryoid/thyrsoid). Optimization of inflorescence characters on a DNA sequence-derived tree suggests that the Asteraceae capitulum derives from a simple cephalioid through two morphological changes: loss of the terminal flower and suppression of the cymose branching pattern in the peripheral branches. • Conclusions: Widely understood as a condensed raceme, the Asteraceae capitulum is the evolutionary result of a very reduced, condensed thyrsoid. Starting from that point, evolution worked separately only on the racemose developmental control/pattern within Asteraceae and mainly on the cymose developmental control/pattern within Calyceraceae, producing head-like inflorescences in both groups but with very different diversification potential. We also discuss possible remnants of the ancestral cephalioid structure in some Asteraceae. © 2012 Botanical Society of America.

Uriu K.,RIKEN | Morelli L.G.,CONICET
Biophysical Journal | Year: 2014

Collective cell movement is a crucial component of embryonic development. Intercellular interactions regulate collective cell movement by allowing cells to transfer information. A key question is how collective cell movement itself influences information flow produced in tissues by intercellular interactions. Here, we study the effect of collective cell movement on the synchronization of locally coupled genetic oscillators. This study is motivated by the segmentation clock in zebrafish somitogenesis, where short-range correlated movement of cells has been observed. We describe the segmentation clock tissue by a Voronoi diagram, cell movement by the force balance of self-propelled and repulsive forces between cells, the dynamics of the direction of self-propelled motion, and the synchronization of genetic oscillators by locally coupled phase oscillators. We find that movement with a correlation length of about 2 ∼ 3 cell diameters is optimal for the synchronization of coupled oscillators. Quantification of cell mixing reveals that this short-range correlation of cell movement allows cells to exchange neighbors most efficiently. Moreover, short-range correlated movement strongly destabilizes nonuniform spatial phase patterns, further promoting global synchronization. Our theoretical results suggest that collective cell movement may enhance the synchronization of the segmentation clock in zebrafish somitogenesis. More generally, collective cell movement may promote information flow in tissues by enhancing cell mixing and destabilizing spurious patterns. © 2014 Biophysical Society.

Camargo A.,Brigham Young University | Camargo A.,CONICET | Avila L.J.,CONICET | Morando M.,CONICET | Sites J.W.,Brigham Young University
Systematic Biology | Year: 2012

Molecular phylogenetics has entered a new era in which species trees are estimated from a collection of gene trees using methods that accommodate their heterogeneity and discordance with the species tree. Empirical evaluation of species trees is necessary to assess the performance (i.e., accuracy and precision) of these methods with real data, which consists of gene genealogies likely shaped by different historical and demographic processes. We analyzed 20 loci for 16 species of the South American lizards of the Liolaemus darwinii species group and reconstructed a species tree with *BEAST, then compared the performance of this method under different sampling strategies of loci, individuals, and sequence lengths. We found an increase in the accuracy and precision of species trees with the number of loci, but for any number of loci, accuracy substantially decreased only when using only one individual per species or 25% of the full sequence length (∼ 147 bp). In addition, locus "informativeness" was an important factor in the accuracy/precision of species trees when using a few loci, but it became increasingly irrelevant with additional loci. Our empirical results combined with the previous simulation studies suggest that there is an optimal range of sampling effort of loci, individuals, and sequence lengths for a given speciation history and information content of the data. Future studies should be directed toward further assessment of other factors that can impact performance of species trees, including gene flow, locus "informativeness," tree shape, missing data, and errors in species delimitation. © 2011 The Author(s).

Ruiz J.J.,CONICET | Saulo C.,CONICET | Nogues-Paegle J.,University of Utah
Monthly Weather Review | Year: 2010

The Weather and Research Forecast model is tested over South America in different configurations to identify the one that gives the best estimates of observed surface variables. Systematic, nonsystematic, and total errors are computed for 48-h forecasts initialized with the NCEP Global Data Assimilation System (GDAS). There is no unique model design that best fits all variables over the whole domain, and nonsystematic errors for all configurations differ little from one another; such differences are in most cases smaller than the observed day-to-day variability. An ensemble mean consisting of runs with different parameterizations gives the best skill for the whole domain. Surface variables are highly sensitive to the choice of land surface models. Surface temperature is well represented by the Noah land model, but dewpoint temperature is best estimated by the simplest land surface model considered here, which specifies soil moisture based on climatology. This underlines the need for better understanding of humid processes at the subgrid scale. Surface wind errors decrease the intensity of the low-level jet, reducing expected heat and moisture advection over southeast South America (SESA), with negative precipitation errors over SESA and positive biases over the South Atlantic convergence zone (SACZ). This pattern of errors suggests feedbacks between wind errors, precipitation, and surface processes as follows: an increase of precipitation over the SACZ produces compensating descent in SESA, with more stable stratification, less rain, less soil moisture, and decreased rain. This is a clear example of how local errors are related to regional circulation, and suggests that improvement of model performance requires not only better parameterizations at the subgrid scales, but also improved regional models. © 2010 American Meteorological Society.

Barral M.P.,CONICET | Oscar M.N.,Instituto Nacional de Tecnologia Agropecuaria
Agriculture, Ecosystems and Environment | Year: 2012

A methodological protocol of strategic environmental assessment was developed to incorporate the valuation of ecosystem services in land use plans. The protocol was applied in rural land planning at Balcarce, a department representative of the Southeast Pampas Region (Argentina). The ecosystem services approach was used as valuation criteria of the 14 principal ecosystems classified in the studied area, where agricultural is the predominant economic activity. The provision of seven principal ecosystem services related to regulation functions or food production was estimated for each ecosystem using a set of indicators integrating climatic, vegetation and terrain variables. The assessment of land use changes showed a significant increase in agriculture in the past 20 years, which affected mainly natural grasslands. The environmental impact of this replacement varied according to the ecosystem and the area. Hills and riparian zones were identified as key areas for grassland conservation in order to provide regulation ecosystem services in agricultural landscapes. On the basis of this analysis, a preliminary zoning was proposed, aimed to retain critical support and regulation ecosystem services without significantly sacrificing food production for humans. Strategic environmental assessment based on ecosystem services appears as a powerful tool to prevent negative environmental costs of land use plans which can remain unnoticed under traditional environmental impact assessment techniques. © 2011 Elsevier B.V.

Colazo J.C.,Instituto Nacional de Tecnologia Agropecuaria | Buschiazzo D.E.,CONICET
Geoderma | Year: 2010

The size and stability of soil aggregates are primary factors that affect the soil susceptibility to wind erosion. Relationships among several soil properties and both the wind erodible fraction (EF) and the dry aggregate stability (DAS) can allow the development of simple mathematical models which can be useful to quantify soil resistance against wind erosion. Considering this we studied 28 cultivated (CULT) and uncultivated (UNCULT) soils of the central semiarid region of Argentina with variable clay, organic carbon (OC), CaCO 3, and amorphous Al (Alo) and Fe (Feo) oxides contents. Results showed that cultivation increased EF and reduced DAS in medium textured soils (silt+clay between 215 and 500gkg -1), but not in sandy (silt+clay<215gkg -1) nor in fine textured soils (silt+clay>500gkg -1). Cultivation of medium textured soils produced the weakening of soil structure through the loss of OC and the breaking down of aggregates. These soils did not contain enough inorganic cementing agents like clay or Alo, which may avoid the deterioration of soil structure. In fine textured soils the formation of large and resistant clods by tillage of cultivated soils produced more similar EF and DAS than in uncultivated conditions. It seems that the lack of EF and DAS differentiation between management systems in sandy soils were produced by their low contents of organic and inorganic cementing agents, even in uncultivated conditions. EF and DAS were related to OC, Alo and clay contents in a logarithmic or an exponentially way. Such relationships allowed the identification of critical OC, Alo and clay contents below which the resistance of the soil against wind erosion is reduced drastically. DAS showed critical values at OC contents of 10gkg -1 in CULT and 29gkg -1 in UNCULT and clay contents of 100gkg -1 in UNCULT. Alo critical contents were 1000gkg -1 for EF and DAS in both managements. There were no effects of Feo and CaCO 3 on EF and DAS in the studied soils. We concluded that the control of wind erosion requires different technologies according to soil texture: management practices which tend to increase the organic matter contents can be successful for the development of large and resistant aggregates which are effective in controlling wind erosion in medium textured soils. The large and stable clods formed by tillage in cultivated fine textured soils are effective in controlling wind erosion. In sandy soils, probably management practices which tend to increase the amount of organic cementing agents of the soil will not be effective in controlling wind erosion. Such goal must be achieved through the increase of coverage of the soil surface with plant residues or canopy. © 2010 Elsevier B.V.

Conicet, Instituto Nacional de Tecnologia Agropecuaria and Inis Biotech Llc | Date: 2012-11-22

Recombinant bacterial strains comprising heterologous nif genes in its genome, and capable of fixing nitrogen. The strain may be, for example, a recombinant Pseudomonas fluorescens strain comprising heterologous nif genes in its genome. An inoculum and a method for increasing plant productivity are further described.

Leiros G.J.,CONICET | Balana M.E.,CONICET
Current Pharmaceutical Biotechnology | Year: 2011

The cancer stem cell (CSC) hypothesis, predicts that a small subpopulation of cancer cells that possess "stemlike" characteristics, are responsible for initiating and maintaining cancer growth. According to the CSC model the many cell populations found in a tumour might represent diverse stages of differentiation. From the cellular point of view metastasis is considered a highly inefficient process and only a subset of tumour cells is capable of successfully traversing the entire metastatic cascade and eventually re-initiates tumour growth at distant sites. Some similar features of both normal and malignant stem cells suggest that CSCs are not only responsible for tumorigenesis, but also for metastases. The CSC theory proposes that the ability of a tumour to metastasize is an inherent property of a subset of CSCs. The similar biological characteristics shared by normal stem cells (NSCs) and CSCs mainly implicate self-renewal and differentiation potential, survival ability, niche-specific microenvironment requirements and specific homing to metastatic sites and may have important implications in terms of new approaches to cancer therapy in the metastatic setting. There are several agents targeting many of these CSC features that have shown to be effective both in vitro and in vivo. Although clinical trials results are still preliminary and continue under investigation, these new therapies are very promising. The identification of new therapeutic targets and drugs based on CSC model constitutes a great challenge. © 2011 Bentham Science Publishers.

Grosse C.,National University of Tucuman | Grosse C.,CONICET
Journal of Physical Chemistry B | Year: 2011

A rigorous extension of the classic Dukhin-Shilov thin double layer polarization theory including the stagnant layer conductivity is presented. Precisely the same assumptions and approximations made in the original theory are maintained, and the same adsorption isotherms are used as in most of the existing numerical calculations. The obtained analytical results improve upon existing approximate extensions, mainly for low surface conductivities and high surface potentials and for high surface conductivities and low surface potentials. Moreover, they avoid the assumption that all the adsorbed ions in the stagnant layer must have a single sign. Finally, they present a very good agreement with numerical calculations specifically made using the same system parameters. © 2011 American Chemical Society.

Gualtieri A.F.,CONICET
Journal of endocrinological investigation | Year: 2011

Controversial effects of bisphenol A (BPA) have been reported on testicular function. These differences might reflect dissimilar exposure conditions. Dose responses to toxicants may be non-linear, e.g. U-shaped, with effects at low and at high levels of exposure and lower or inexistent effects at intermediate levels. Sertoli cells produce high levels of glutathione (GSH) as a cell defense mechanism. In this study, we addressed the question whether the exposure to different doses of BPA could influence Sertoli cell GSH synthesis and recycling. Primary Sertoli cell cultures were exposed to various doses of BPA (0.5 nM-100 μM). Cell viability was measured as an outcome of toxic effect. GSH cell content was determined to evaluate cell response to toxicant exposure. Glutamate-cysteine ligase catalytic (GCLC) and modulatory (GCLM) subunit expression were assessed to estimate GSH synthesis, and GSH reductase (GR) expression to estimate GSH recycling. BPA 100 μM, but not lower doses, decreased cell viability. BPA 10 and 50 μM, but not lower doses, induced an increment in Sertoli cell GSH levels, due to a rapid upregulation of GCLC and GR and a slower upregulation of GCLM. High doses of BPA are deleterious for Sertoli cells. Intermediate doses do not affect Sertoli cell viability and increase cell content of GSH owing to increased GSH synthesis and recycling enzyme expression. Lower doses of BPA are not capable of eliciting a cell defense response. These observations may explain a non-linear dose response of Sertoli cells to BPA.

Manzano M.F.G.,CONICET | Igarzabal C.I.A.,CONICET
Journal of Molecular Catalysis B: Enzymatic | Year: 2011

Novel hydrogels based on N-acryloyl-tris(hydroxymethyl) aminomethane (NAT), 2-aminoethyl methacrylate (AEMA) and N,N′-methylenebisacrylamide (BIS) were prepared and applied for immobilization of lipase. Two procedures were previously performed on the hydrogels as follows: (a) modification with epichlorohydrin (ECH) or 1,4-butanediol diglycidyl ether (BDGE) or (b) grafting with AEMA, using ceric ammonium sulfate as an initiator, and subsequent reaction with ECH. In the hydrolysis reactions, high percentages of lipase activity were reached with products whose enzyme immobilization were performed on both BDGE-containing products and grafted matrices, since the enzyme was bound spaced from the matrices and more likely to interact with the substrate. The best derivatives preserved 86.7-89.5% of the activity corresponding to the soluble enzyme. © 2011 Elsevier B.V.

Materials based on titania directly modified with tungstophosphoric acid were prepared using titanium isopropoxide as titania precursor and urea as a low-cost pore-forming agent. The obtained mesoporous solids presented an average pore diameter higher than 3.1 nm. The specific surface area decreased when the TPA amount and the calcination temperature increased. All the modified solids only showed the anatase structure of titania by X-ray diffraction, while for the unmodified sample this structure was transformed into the rutile phase from 600 °C on. The crystallite size increased with the calcination temperature, though the TPA-modified samples presented lower values when the TPA amount was increased. The 31P nuclear magnetic resonance studies showed that the Keggin structure of the tungstophosphate anion was partially transformed when it was thermally treated up to 600 °C, though structure disruption took place at higher temperature. The band gap values estimated from the UV-vis-diffuse reflectance spectra did not show important variation, though they slightly decreased with the TPA content. The 4-chlorophenol degradation was studied in liquid phase, with an air flow continuously bubbled. The degradation behavior of the catalysts as a function of time depended on the TPA amount and the thermal treatment temperature, the samples containing 30% TPA calcined at 500-600 °C and 20% TPA calcined at 600 °C being more effective. The apparent reaction constant, estimated assuming a pseudo-first-order kinetics, followed the same trend. The catalysts can be reused at least three times without an important decrease in the degradation and mineralization degrees. © 2011 Elsevier B.V. All rights reserved.

Gebhard L.G.,CONICET | Kaufman S.B.,University of Buenos Aires | Gamarnik A.V.,CONICET
PLoS ONE | Year: 2012

The flavivirus nonstructural protein 3 (NS3) bears multiple enzymatic activities and represents an attractive target for antiviral intervention. NS3 contains the viral serine protease at the N-terminus and ATPase, RTPase, and helicase activities at the C-terminus. These activities are essential for viral replication; however, the biological role of RNA remodeling by NS3 helicase during the viral life cycle is still unclear. Secondary and tertiary RNA structures present in the viral genome are crucial for viral replication. Here, we used the NS3 protein from dengue virus to investigate functions of NS3 associated to changes in RNA structures. Using different NS3 variants, we characterized a domain spanning residues 171 to 618 that displays ATPase and RNA unwinding activities similar to those observed for the full-length protein. Interestingly, we found that, besides the RNA unwinding activity, dengue virus NS3 greatly accelerates annealing of complementary RNA strands with viral or non-viral sequences. This new activity was found to be ATP-independent. It was determined that a mutated NS3 lacking ATPase activity retained full-RNA annealing activity. Using an ATP regeneration system and different ATP concentrations, we observed that NS3 establishes an ATP-dependent steady state between RNA unwinding and annealing, allowing modulation of the two opposing activities of this enzyme through ATP concentration. In addition, we observed that NS3 enhanced RNA-RNA interactions between molecules representing the ends of the viral genome that are known to be necessary for viral RNA synthesis. We propose that, according to the ATP availability, NS3 could function regulating the folding or unfolding of viral RNA structures. © 2012 Gebhard et al.

Martinez E.A.,University of Buenos Aires | Paz J.P.,University of Buenos Aires | Paz J.P.,CONICET
Physical Review Letters | Year: 2013

We analyze the evolution of the quantum state of networks of quantum oscillators coupled with arbitrary external environments. We show that the reduced density matrix of the network always obeys a local master equation with a simple analytical solution. We use this to study the emergence of thermodynamical laws in the long time regime demonstrating two main results: First, we show that it is impossible to build a quantum absorption refrigerator using linear networks (thus, nonlinearity is an essential resource for such refrigerators recently studied by Levy and Kosloff and Levy et al.). Then, we show that the third law imposes constraints on the low frequency behavior of the environmental spectral densities. © 2013 American Physical Society.

Kornblihtt A.R.,CONICET | Schor I.E.,CONICET | Allo M.,CONICET | Dujardin G.,CONICET | And 2 more authors.
Nature Reviews Molecular Cell Biology | Year: 2013

Alternative splicing was discovered simultaneously with splicing over three decades ago. Since then, an enormous body of evidence has demonstrated the prevalence of alternative splicing in multicellular eukaryotes, its key roles in determining tissue-and species-specific differentiation patterns, the multiple post-and co-transcriptional regulatory mechanisms that control it, and its causal role in hereditary disease and cancer. The emerging evidence places alternative splicing in a central position in the flow of eukaryotic genetic information, between transcription and translation, in that it can respond not only to various signalling pathways that target the splicing machinery but also to transcription factors and chromatin structure. © 2013 Macmillan Publishers Limited. All rights reserved.

Miller Bertolami M.M.,Max Planck Institute for Astrophysics | Miller Bertolami M.M.,CONICET
Astronomy and Astrophysics | Year: 2014

Context. Recent determinations of the white dwarf luminosity function (WDLF) from very large surveys have extended our knowledge of the WDLF to very high luminosities. This, together with the availability of new full evolutionary white dwarf models that are reliable at high luminosities, have opened the possibility of testing particle emission in the core of very hot white dwarfs, where neutrino processes are dominant. Aims. We use the available WDLFs from the Sloan Digital Sky Survey and the SuperCOSMOS Sky Survey to constrain the value of the neutrino magnetic dipole moment (μν). Methods. We used a state-of-the-art stellar evolution code to compute a grid of white dwarf cooling sequences under the assumptions of different values of μν. Then we constructed theoretical WDLFs for different values of μν and performed a χ2-test to derive constraints on the value of μν. Results. We find that the WDLFs derived from the Sloan Digital Sky Survey and the SuperCOSMOS Sky Survey do not yield consistent results. The discrepancy between the two WDLFs suggests that the uncertainties are significantly underestimated. Consequently, we constructed a unified WDLF by averaging the SDSS and SSS and estimated the uncertainties by taking into account the differences between the WDLF at each magnitude bin. Then we compared all WDLFs with theoretical WDLFs. Comparison between theoretical WDLFs and both the SDSS and the averaged WDLF indicates that μν should be μν < 5 × 10 -12 eħ/(2mec). In particular, a χ2-test on the averaged WDLF suggests that observations of the disk WDLF exclude values of μν > 5 × 10 -12eħ/(2mec) at more than a 95% confidence level, even when conservative estimates of the uncertainties are adopted. This is close to the best available constraints on μν from the physics of globular clusters. Conclusions. Our study shows that modern WDLFs, which extend to the high-luminosity regime, are an excellent tool for constraining the emission of particles in the core of hot white dwarfs. However, discrepancies between different WDLFs suggest there might be some relevant unaccounted systematic errors. A larger set of completely independent WDLFs, as well as more detailed studies of the theoretical WDLFs and their own uncertainties, is desirable to explore the systematic uncertainties behind this constraint. Once this is done, we believe the Galactic disk WDLF will offer constraints on the magnetic dipole moment of the neutrino similar to the best available constraints obtainable from globular clusters. © 2014 ESO.

Murgida G.E.,CONICET | Ganduglia-Pirovano M.V.,Institute Catalisis Y Petroleoquimica Of The Consejo Superior Of Investigaciones Cientificas
Physical Review Letters | Year: 2013

Oxygen vacancies on ceria (CeO2) surfaces play a crucial role in catalytic applications, yet whether vacancies are at surface or subsurface sites on reduced CeO2(111), and whether vacancies agglomerate or repel each other, is still under discussion, with few and inconsistent experimental results. By combining density-functional theory (DFT) in the DFT+U (U is an effective onsite Coulomb interaction parameter) approach and statistical thermodynamics, we show that the energetically most stable near-surface oxygen vacancy structures for a broad range of vacancy concentrations, Θ (116≤Θ≤1 monolayer) have all vacancies at subsurface oxygen sites and predict that the thermodynamically stable phase for a wide range of reducing conditions is a (2×2) ordered subsurface vacancy structure (Θ=14). Vacancy-induced lattice relaxations effects are crucial for the interpretation of the repulsive interactions, which are at the basis of the vacancy spacing in the (2×2) structure. The findings provide theoretical data to support the interpretation of the most recent experiments, bringing us closer to solving the debate. © 2013 American Physical Society.

Corradi J.,CONICET | Bouzat C.,CONICET
Molecular Pharmacology | Year: 2016

The nicotinic acetylcholine receptor (nAChR) belongs to a superfamily of pentameric ligand-gated ion channels involved in many physiologic and pathologic processes. Among nAChRs, receptors comprising the α7 subunit are unique because of their high Ca2+ permeability and fast desensitization. nAChR agonists elicit a transient ion flux response that is further sustained by the release of calcium from intracellular sources. Owing to the dual ionotropic/metabotropic nature of a7 receptors, signaling pathways are activated. The α7 subunit is highly expressed in the nervous system, mostly in regions implicated in cognition and memory and has therefore attracted attention as a novel drug target. Additionally, its dysfunction is associated with several neuropsychiatric and neurologic disorders, such as schizophrenia and Alzheimer's disease. α7 is also expressed in non-neuronal cells, particularly immune cells, where it plays a role in immunity, inflammation, and neuroprotection. Thus, α7 potentiation has emerged as a therapeutic strategy for several neurologic and inflammatory disorders. With unique activation properties, the receptor is a sensitive drug target carrying different potential binding sites for chemical modulators, particularly agonists and positive allosteric modulators. Although macroscopic and singlechannel recordings have provided significant information about the underlying molecular mechanisms and binding sites of modulatory compounds, we know just the tip of the iceberg. Further concerted efforts are necessary to effectively exploit α7 as a drug target for each pathologic situation. In this article, we focus mainly on the molecular basis of activation and drug modulation of α7, key pillars for rational drug design. © 2016 by The American Society for Pharmacology and Experimental Therapeutics.

Ponce J.J.,National University of Rio Negro | Carmona N.,CONICET
Geology | Year: 2011

In this paper we present an outcrop example of coarse-grained sediment waves generated by hyperpycnal discharges at the toe of Miocene clinoform systems exposed in the northeast Atlantic coast of Tierra del Fuego, Argentina. An individual set of these sediment waves is formed during the waxing and waning phases of the hyperpycnal discharge. During the waxing phase, accumulation of coarse-grained sediments with generation and migration of dune bedforms occurs at the base of the clinoforms. These deposits show transitions of tractive sedimentary structures with evidence of bedload transport, and a continuous reworking by the overpassing hyperpycnal flow. The continued erosion and reworking during the waxing phase affect mainly the top and the stoss side of the dunes, resulting in isolated lenses having upcurrent aggradation structures. During the waning phase, these isolated lenses are covered by fine-grained heterolithic strata that are thicker on the stoss side than on the lee side, constituting a differential draping. The pulsating and sustained character of the hyperpycnal flows and the steep depositional slope clinoforms controlled the stacking pattern of the coarse-grained sediment waves during successive hyperpycnal events. In this way, small-scale, coarse-grained sediment waves, with wavelengths of 10-40 m and up to 5 m amplitude, and a stacking pattern showing an up-current growth, are generated by high-density hyperpycnal flows on slopes having steep gradients. © 2011 Geological Society of America.

Folguera A.,CONICET | Ramos V.A.,CONICET
Journal of South American Earth Sciences | Year: 2011

The Southern Andes have been built through the stacking of crustal sheets in discrete periods during the last 100 My. The first important shortening took place in Late Cretaceous at the time of eastward arc expansions potentially linked to two areas of subducted slab shallowings of 200 and 800 km wide respectively. These shallowings have progressed to two smaller flat slabs in Eocene times, where rather anhydrous subducted slabs generated a discontinuous arc emplaced in the foreland area at the time of mountain building. Discrete segments of the former Late Cretaceous slab shallowings would have fallen down at this time producing early slab steepening settings where within-plate products and extensional basins developed such as in the southern Chubut Province. Then Late Oligocene times coincide with the final steepening of the broad Late Cretaceous to Eocene shallow subduction zone with the emplacement of voluminous volcanic plateaux in central Patagonia and extensional basins in the hinterland zone. Lately a long quiescence period was interrupted by the development of three Miocene shallow subduction settings more than 400 km long each, evidenced by arc expansions and associated with Andean construction. Most of these areas were extensionally reactivated in the last 5 My at the time of retraction and steepening of formerly shallow subduction zones, being associated with voluminous mantle derived materials and shallow asthenospheric injection. While some of these shallow subduction configurations could be explained by subduction of highly buoyant oceanic lithosphere related to seismic ridges, in particular those of the Aluk/Farallones and Chilean ridges, other mechanisms remain more speculative. The alternation of shallow subduction zones and their steepening in the last 100 My in the Southern Andes explain location and timing of main magmatic fluxes in the arc and retroarc areas, as well as the presence of coeval foreland mountain systems east of the Main Andes. © 2011 Elsevier Ltd.

Molecular BioSystems | Year: 2012

Disordered regions are segments of a protein that do not fold completely and thus remain flexible. These regions have key physiological roles, particularly in phospho-proteins, which are enriched in disorder-promoting residues surrounding their phosphorylation sites. 14-3-3 proteins are ordered hubs that interact with multiple and diverse intrinsically disordered phosphorylated targets. This provides 14-3-3 with the ability to participate in and to regulate multiple signalling networks. Here, I review the effect of structural disorder on the mechanism involved in 14-3-3 protein-protein interactions and how 14-3-3 impacts cell biology through disordered ligands. How 14-3-3 proteins constitute an advantageous system to identify novel classes of biological tools is discussed with a special emphasis on a particular - and innovative - use of small molecules to stabilize 14-3-3 protein complexes, useful to study gene expression, cancer signalling and neurodegenerative diseases.

As in other parts of the world, the northern coast of the San Matías Gulf (Northern Patagonia, Argentina) has undergone remarkable changes after the Middle Holocene sea level maximum. By means of an interdisciplinary work, the geomorphologic evolution of Bajo de la Quinta coastal hollow was reconstructed since ca. 600014CBP, when the oldest human occupation of the area was detected. Main recorded changes in coastal configuration seem to have had a noticeable influence in both the use of marine resources along time by native hunter-gatherer groups, and the preservation of the archaeological evidence. With respect to the first issue, changes in human paleodiets and fishing practices could be related with the sedimentary filling and rectification of this littoral after the high marine level scenario. This study highlights the importance of reconstructing past scenarios of human activities for archaeological interpretation, in particular when studying high dynamic environments such as the coastal landscape. © 2011 Elsevier Ltd and INQUA.

This paper deals with the way in which the environmental dynamics that took place in the lower basin of the Colorado River (Buenos Aires province, Argentina) have affected the degree of archaeological resolution, integrity, and site preservation in different sectors of the study area (e.g., coastal fringe, delta and interior dune fields). Evidence from geomorphologic, stratigraphic, and sedimentary analyses as well as chemical parameters and zooarchaeological assemblages are used in order to propose spatial and temporal variations in the structure of the archaeological record. These lines of evidence were also used for inferring general paleoclimatic trends. The results obtained indicate that the inland landforms that contained Initial Late Holocene archaeological assemblages (3000-1000 14C BP) have suffered important morphodynamic processes that produced site destruction, loss of organic material and lower degrees of integrity and site resolution. Conversely, landforms located near the delta and the coastal fringe underwent more stable geomorphic processes (e.g., pedogenesis) that promoted better preservation, resolution, and integrity during the Initial Late Holocene and, particularly, during the Final Late Holocene (1000-250 14C BP). The recognition of this pattern is crucial in order to evaluate demographic processes linked with the intensity and mode of hunter-gatherer occupation of the area and population dynamics throughout time. © 2011 Elsevier Ltd and INQUA.

Megalonychidae are known from the Deseadan of Argentina and Bolivia to the present, represented by the tree sloth Choloepus Illiger. The principal fossil records of this clade are those from the Quaternary of Central America and the Antilles (e.g., Megalocnus Leidy, Acratocnus Anthony) and North America (e.g., Megalonyx Harlan, Pliometanastes Hirschfeld and Webb). From the Quaternary of South America, Megalonychidae are recorded in Peru (Diabolotherium Pujos, De Iuliis, Argot and Werdelin) and Brazil (e.g., Ahytherium Cartelle, De Iuliis and Pujos, Australonyx De Iuliis, Pujos and Cartelle). In Argentina they also have been recorded in the Santa Cruz Formation (early-middle Miocene) on the coast of Santa Cruz Province (Eucholaeops Ameghino), Arroyo Chasicó Formation (Protomegalonyx Kraglievich), Río Negro Formation, in the " conglomerado osífero" (ossiferous conglomerate) or " Mesopotamiense" (late Miocene) at the base of Ituzaingó Formation, Entre Ríos Province, and Pleistocene of Buenos Aires Province. Several authors have studied the Megalonychidae from the " conglomerado osífero", but no systematic revision of the group has been undertaken beyond the original naming of species. Taking into account that a broad range of individual variation has been observed in the Megalonychidae from the Pleistocene of North America and the West Indies, and that a similar range probably existed among the megalonychids from the " conglomerado osífero", then the number of valid species might be lower than previously proposed. Thus, the valid species recovered from the " conglomerado osífero" are Ortotherium laticurvatum Ameghino, Pliomorphus mutilatus Ameghino, Amphiocnus paranense Kraglievich, Protomegalonyx doellojuradoi Kraglievich, Pr. Praecursor Kraglievich, Megalonychops primigenius Kraglievich, and Paranabradys vucetichae Scillato-Yané. However, the establishment of synonymies, as well as the generic and specific assignation of the specimens is not an easy task, due to the peculiar taphonomical context of this stratigraphic unit. © 2010 Elsevier Masson SAS.

Within the framework of the CLARIS-LPB EU Project, a suite of 7 coordinated Regional Climate Model (RCM) simulations over South America driven by both the ERA-Interim reanalysis and a set of Global Climate Models (GCMs) were evaluated. The systematic biases in simulating monthly mean temperature and precipitation from the 2 sets of RCM simulations were identified. The Climate Research Unit dataset was used as a reference. The systematic model errors were more dependent on the RCMs than on the driving GCMs. Most RCMs showed a systematic temperature overestimation and precipitation underestimation over the La Plata Basin region. Model biases were not invariant, but a temperature-dependent temperature bias and a precipitation-dependent precipitation bias were apparent for the region, with the warm bias amplified for warm months and the dry bias amplified for wet months. In a climate change scenario, the relationship between model bias behaviour and the projected climate change for each individual model revealed that the models with the largest temperature bias amplification projected the largest warming and the models with the largest dry bias amplification projected the smallest precipitation increase, suggesting that models' bias behaviour may affect the future climate projections. After correcting model biases by means of a quantile-based mapping bias correction method, projected temperature changes were systematically reduced, and projected precipitation changes were systematically increased. Though applying bias correction method - ologies to projected climate conditions is controversial, this study demonstrates that bias correction methodologies should be considered in order to better interpret climate change signals. © Inter-Research 2016.

Giribet G.,University of Buenos Aires | Leston M.,CONICET
Journal of High Energy Physics | Year: 2010

Resorting to the notion of a stress-tensor induced on the boundary of a spacetime, we compute the conserved charges associated to exact solutions of New Massive Gravity that obey weakened versions of AdS 3 asymptotic boundary conditions. The computation requires the introduction of additional counterterms, which play the rǒle of regularizing the semiclassical stress-tensor in the boundary theory. We show that, if treated appropriately, different ways of prescribing asymptotically AdS 3 boundary conditions yield finite conserved charges for the solutions. The consistency of the construction manifests itself in that the charges of hairy asymptotically AdS 3 black holes computed by this holographyinspired method exactly match the values required for the Cardy formula to reproduce the black hole entropy. We also consider new solutions to the equations of motion of New Massive Gravity, which happen to fulfill Brown-Henneaux boundary conditions despite not being Einstein manifolds. These solutions are shown to yield vanishing boundary stresstensor. The results obtained in this paper can be regarded as consistency checks for the prescription proposed in [1]. © SISSA 2010.

Kovalsky M.,CONICET | Hnilo A.,CONICET
Optics Letters | Year: 2010

We report the experimental and theoretical verification that, in a diode-pumped Nd:YAG + Cr:YAG Q-switched laser, the instabilities in the pulse spacing ("jitter") are ruled by low-dimensional deterministic chaos. From our experimental time series, we determine the embedding and fractal dimensions of the attractor, as well as the values of the Lyapunov exponents. We also present a simplified theoretical description in terms of a map of the same universality class as the logistic map, which explains the bifurcations' cascade and the period-three window of stability observed. The achieved characterization of the dynamics and its main parameters opens a door to effective ways to reduce the jitter, which is of practical interest, through mechanisms of control of chaos. Conversely, the difficulty in the prediction of the interpulse spacing makes this system attractive for high power, robust FM chaotic laser cryptography in free-space propagation. © 2010 Optical Society of America.

Karasov W.H.,University of Wisconsin - Madison | Martinez Del Rio C.,University of Wyoming | Caviedes-Vidal E.,CONICET
Annual Review of Physiology | Year: 2011

The morphological and functional design of gastrointestinal tracts of many vertebrates and invertebrates can be explained largely by the interaction between diet chemical constituents and principles of economic design, both of which are embodied in chemical reactor models of gut function. Natural selection seems to have led to the expression of digestive features that approximately match digestive capacities with dietary loads while exhibiting relatively modest excess. Mechanisms explaining differences in hydrolase activity between populations and species include gene copy number variations and single-nucleotide polymorphisms. In many animals, both transcriptional adjustment and posttranscriptional adjustment mediate phenotypic flexibility in the expression of intestinal hydrolases and transporters in response to dietary signals. Digestive performance of animals depends also on their gastrointestinal microbiome. The microbiome seems to be characterized by large beta diversity among hosts and by a common core metagenome and seems to differ flexibly among animals with different diets. © 2011 by Annual Reviews. All rights reserved.

Garbarz A.,National University of La Plata | Leston M.,CONICET
Journal of High Energy Physics | Year: 2014

We revisit the description of the space of asymptotically AdS3 solutions of pure gravity in three dimensions with a negative cosmological constant as a collection of coadjoint orbits of the Virasoro group. Each orbit corresponds to a set of metrics related by diffeomorphisms which do not approach the identity fast enough at the boundary. Orbits contain more than a single element and this fact manifests the global degrees of freedom of AdS3 gravity, being each element of an orbit what we call boundary graviton. We show how this setup allows to learn features about the classical phase space that otherwise would be quite difficult. Most important are the proof of energy bounds and the characterization of boundary gravitons unrelated to BTZs and AdS3. In addition, it makes manifest the underlying mathematical structure of the space of solutions close to infinity. Notably, because of the existence of a symplectic form in each orbit, being this related with the usual Dirac bracket of the asymptotic charges, this approach is a natural starting point for the quantization of different sectors of AdS3 gravity. We finally discuss previous attempts to quantize coadjoint orbits of the Virasoro group and how this is relevant for the formulation of AdS3 quantum gravity. © 2014 The Authors.

Elizalde E.,CONICET | Urteaga R.,CONICET | Koropecki R.R.,CONICET | Berli C.L.A.,CONICET
Physical Review Letters | Year: 2014

The inverse problem of capillary filling, as defined in this work, consists in determining the capillary radius profile from experimental data of the meniscus position l as a function of time t. This problem is central in diverse applications, such as the characterization of nanopore arrays or the design of passive transport in microfluidics; it is mathematically ill posed and has multiple solutions; i.e., capillaries with different geometries may produce the same imbibition kinematics. Here a suitable approach is proposed to solve this problem, which is based on measuring the imbibition kinematics in both tube directions. Capillary filling experiments to validate the calculation were made in a wide range of length scales: glass capillaries with a radius of around 150μm and anodized alumina membranes with a pores radius of around 30nm were used. The proposed method was successful in identifying the radius profile in both systems. Fundamental aspects also emerge in this study, notably the fact that the l(t)t1/2 kinematics (Lucas-Washburn relation) is not exclusive of uniform cross-sectional capillaries. © 2014 American Physical Society.

Superina M.,CONICET | Pagnutti N.,National University of La Plata | Abba A.M.,National University of La Plata
Mammal Review | Year: 2014

Basic knowledge on the biology and ecology of a species is fundamental for the realistic assessment of its conservation status and for planning effective conservation strategies. The latest assessment of the 21 extant armadillo species (Xenarthra, Dasypodidae) by the International Union for Conservation of Nature (IUCN) for its Red List of Threatened Species shows that considerable gaps exist in our knowledge of these Neotropical mammals. Our goal was to analyse the existing literature on armadillos to define thematic and regional research priorities that will eventually benefit their conservation. We categorized 3117 publications on extant armadillos published between 1660 and 2011 according to their research topic, species studied, country and publication language. The number of publications per research topic and the number per species were very variable. The nine best-studied species are classed as Least Concern by the IUCN, while three of the four least-studied species are classed as Data Deficient. At least one field study was done in each range country, but over 80% of field research took place in the USA, Brazil, Argentina and Bolivia. Most research was done in the USA on leprosy in Dasypus novemcinctus. Most ecological research has been focused on four species, and data on the ecology of Data Deficient and Vulnerable taxa are virtually absent. Field research on armadillos should be intensified to broaden conservation-relevant knowledge. Additional studies in the Guianas, Peru, Ecuador, Colombia, Venezuela and Paraguay are urgently needed to assess the conservation status of armadillos in these regions. Future research should focus on ecology, conservation, population genetics, reproduction and threats. Species priorities should include country endemics, such as Dasypus pilosus (Peru), Tolypeutes tricinctus (Brazil) and Dasypus yepesi and Chlamyphorus truncatus (Argentina), as well as other Data Deficient and Vulnerable species, especially Cabassous centralis and Calyptophractus retusus. © 2013 The Mammal Society and John Wiley & Sons Ltd.

Cordoba A.L.,CONICET | Deladino L.,CONICET | Martino M.,CONICET
Carbohydrate Polymers | Year: 2014

Encapsulation of yerba mate (Ilex paraguariensis) extract in a proper matrix enhances the possible applications of this natural antioxidant in food systems. To start, calcium alginate capsules were used as carriers of yerba mate extract and a filler material (corn starch at 2%) was added to the alginate matrix to improve the structural properties and to modulate the release of the active compounds. Next, kinetics and swelling mechanisms involved in the release of yerba mate polyphenols in simulated digestive fluids were analyzed. A lower rate of release was obtained with calcium alginate-starch capsules as compared to control ones, which was attributed to the lower porosity of filled capsules. The release profiles of both systems were satisfactorily fitted with semi-empirical models, which indicated that a combined mechanism of polymer-chain relaxation and diffusion was taking place. © 2013 Elsevier Ltd. All rights reserved.

Aim: Our aims were: (1) to study the shape of the species richness-elevation and abundance-elevation relationships (SRER and AER, respectively) in epigaeic mountain beetles; and (2) to analyse how richness and abundance of the beetles vary across the full gradient and within the forests and steppes in association with environmental variables representing productivity, thermal limitation, water-energy dynamics, environmental heterogeneity and soil characteristics. Location: Five mountains at temperate latitudes in north-western Patagonia, Argentina. Methods: We collected beetles using 486 pitfall traps arranged in fifty-four 100 m2 grid plots of nine traps, established at intervals of about 100 m of elevation from the base to the summit of each mountain. We used multi-model selection and the Akaike information criterion to find the best ecological explanation for species richness and abundance variation. Results: The AER was hump-shaped in four mountains and negative in one; the SRER was negative in one case, humped in two cases, and either low-plateau or humped in the remaining two. Across the full gradient, the increase in vegetation cover, mainly associated with the presence of forests, predominately accounted for SRERs and AERs. In the forests, energy variables combined with precipitation, soil attributes and environmental heterogeneity accounted for richness and abundance. In the steppes, potential evapotranspiration and plant productivity were important. Main conclusions: We confirmed different forms in the shape of SRERs, and the predominance of hump-shaped patterns in AERs. Vegetation type (forests versus steppes) accounted for most of the variation in species richness and abundance on all mountains. Associations with local environmental factors were rather more variable and changed with the spatial extent of analysis, thus confirming the spatial dependence of the species richness/abundance-environment relationships. © 2013 John Wiley & Sons Ltd.

Natural disturbances are important components of ecosystem dynamics. Large scale disturbances produced by volcanoes, have been poorly studied because of their low frequency, the lack of baseline studies due to their unpredictability, the impossibility of replication, and the diffculty of conducting long-term studies to monitor ecosystem recovery. The recent eruption of the Puyehue-Cordón Caulle volcanic complex (June 2011), which produced an ash fall covering 24 million ha of Patagonia, provides a unique opportunity of studying this type of disturbance in areas with baseline data. The summer before the ash fall (2011) ant communities were characterized in areas of the Patagonian steppe which were later covered with 4 cm of fne ash. The aim of this study is to establish if ash deposition affected ant abundance, species richness and composition. In summers 2012 and 2013, sampling was repeated and data obtained were compared among years. Total ant abundance tended to be lower after the eruption, but species richness and composition were similar before and two seasons after the ash fall. The little effects on ant community is mainly a consequence of the timing of the eruption, ants' social nature, and ash thickness. The eruption occurred at the end of the autumn when ant activity was reduced due to low temperatures. Also, the potential mortality of outside workers during the acute deposition phase does not risk colony survival since they represent a small percentage of it. Ash thickness was probably not high enough to produce severe effects. Only four out of 13 species changed their incidence after the ash fall, three of them not until the second season, showing a delayed response. This was probably a consequence of indirect effects mediated by resource and environmental changes. Long-term effects on other species cannot be discarded.

Schmiegelow C.T.,CONICET | Schmidt-Kaler F.,Johannes Gutenberg University Mainz
European Physical Journal D | Year: 2012

We study the interaction of light beams carrying angular momentum with a single, trapped and well localized ion. We provide a detailed calculation of selection rules and excitation probabilities for quadrupole transitions. The results show the dependencies on the angular momentum and polarization of the laser beam as well as the direction of the quantization magnetic field. In order to optimally observe the specific effects, focusing the angular momentum beam close to the diffraction limit is required. We discuss a protocol for examining experimentally the effects on the S 1/2 to D 5/2 transition using a 40Ca + ion. Various applications and advantages are expected when using light carrying angular momentum: in quantum information processing, where qubit states of ion crystals are controlled, parasitic light shifts could be avoided as the ion is excited in the dark zone of the beam at zero electric field amplitude. Such interactions also open the door to high dimensional entanglement between light and matter. In spectroscopy one might access transitions which have escaped excitation so far due to vanishing transition dipole moments. © EDP Sciences, Società Italiana di Fisica, Springer-Verlag 2012.

Advances in Limnology | Year: 2014

The Río de la Plata is an extensive, shallow, and microtidal coastal-plain estuary on the east coast of South America. The river receives freshwater from South America's second largest watershed. The main tributaries are the Paraná and Uruguay rivers, characterized by flows with opposing patterns of seasonal variability. The dynamics of the Río de la Plata Estuary is controlled by tides, wind-driven waves, and continental runoff. This ecosystem is of great socioeconomic importance since industrial and urban areas throughout the region affect the aquatic habitats. Furthermore, this river is used for several purposes, including drinking water, recreational and navigational activities, but at the same time it receives agricultural runoff and industrial and domestic wastes. The ecology of the phytoplankton of the Río de la Plata has been only scarcely explored, particularly those organisms relating to the freshwater tidal zone. The work reported here, investigated the principal abiotic conditions that influence the composition and distribution of phytoplankton, as well the life-form strategies of the algae along the fluvial-mixohaline axis. The structural characteristics such as taxonomic groups, species richness, density, biomass, diversity, and size are described. Upon consideration of the availability of nutrients and the residence time of the water within the ecosystem, the risk of the spread of blooms is also analyzed. © 2014 E. Schweizerbart'sche Verlagsbuchhandlung, 70176 Stuttgart, Germany.

Tinamous are volant terrestrial birds, endemic to the Neotropics. Here, an inclusive phenotype-based phylogenetic study of the interrelationships among all extinct and living species of tinamous is conducted. In this cladistic analysis, results are compared between main character subsets and with previous molecular studies. Special attention is paid to character definition and scoring of integumentary and behavioural characters: transformation costs are applied to analyse egg coloration and plumage characters-on the basis of pigment composition and overlap of pigmentation patterns respectively-in the context of generalized (Sankoff) parsimony. Cladistic analysis recovers the traditional subdivision between those tinamous specialized for open areas (Nothurinae) and those inhabiting forested environments (Tinaminae) and support the monophyly of recognized genera. The present study demonstrates that morphological analysis yields highly congruent results when compared with previous molecular studies; thus, it provides morphological synapomorphies for clades that have been proposed by these molecular analyses. The placement of the fossil species within the open-area (Nothurinae) and the forest-dwelling (Tinaminae) tinamous is also consistent with the palaeoenvironmental conditions inferred from the associated flora and fauna. © 2016 The Willi Hennig Society.

Modenutti B.,CONICET
Advances in Limnology | Year: 2014

Mixotrophic organisms appeared in photosynthetic and heterotrophic lineages (i.e., algae and ciliates). In this article we will present examples and discuss diverse aspects of the success of this dual nutrition mode in different lakes from Argentina. Factors as nutrients, light, water mixing intensity, mixing depth, and prey abundance have large effects on the ecological dynamics of these organisms. Traditional studies suggested that the growth rate of mixotrophic protists would depend on light intensity and prey abundance allowing the classification of mixotrophs into different groups. We will discuss this scheme in the scenario of protists currently present in Argentina. Additionally, we will examine the results of field and experimental studies in Argentina lakes regarding the different co-occurring factors that determine the success of different mixotrophic species. In particular, we will focus competitive interactions among mixotrophs in nature, evaluating both, photosynthetic efficiency as a result of the niche partitioning along the water column and the ingestion of picoprokaryotes for food niche overlap. Furthermore, we will present other studies on the relative importance of light (intensity and quality) in the autotrophy and phagotrophy balance. © 2014 E. Schweizerbart'sche Verlagsbuchhandlung, 70176 Stuttgart, Germany.

Premise of research. Most studies of Anacardiaceae embryology have focused on seed and fruit development in different genera. None of them, however, included species of Schinopsis. Considering the absence of embryological data and the precedents of chalazogamy in the Anacardiaceae family, the aims of this study were to complete the embryological studies in Schinopsis balansae, providing information about micro-and megasporogen-esis and gametogenesis, fertilization, and embryogenesis, and to investigate the development of the gynoecium and the pathway of the pollen tube. Methodology. Flowers and fruits of S. balansae, a dioecious tree from the family Anacardiaceae, were collected and fixed in the field. The embryology was examined using fluorescence microscopy, LM, and SEM. Microtome section series were used to reconstruct the structure and pollen tube pathway. Pivotal results. Staminate flowers have only rudimentary gynoecia, and the anthers are bithecal and tetrasporangiate. The tapetum is secretory and uninucleate, and the pollen grains are bicellular. The morphologically bisexual flowers are functionally pistillate, and staminodia without sporogenous tissue or pollen grains are present. The pistillate flowers have a superior tricarpellate ovary with three styles, each ending in a capitate stigma. The gynoecium is pseudomonomerous, possessing one fertile carpel (with one locule and a single anatropous, crassinucellar, and unitegmic ovule) and two aborted lateral carpels that neither produce an ovule nor form a locule. Embryo sac development conformed to the Polygonum type. Bicellular pollen grains germinate on the stigma and penetrate the transmitting tract inside the styles. At the apical portion of the ovary, pollen tubes grow through the carpel wall and reach the dorsal portion of the bent funicle, which is in close contact and forms a functional ponticulus. Inside the funicle, the pollen tubes continue through the vascular bundle, where they are branched. One branch continues inside the vascular bundle to the chalaza. Fertilization was aporogamous: the pollen tubes encircled the embryo sac, reaching one synergid. Embryos follow the Onagrad type. The endosperm development is of the coenocytic/multicellular type. Conclusions. The structural floral features described here are shared by other species of Anacardiaceae. The results of the embryological studies in S. balansae provide information about micro-and megasporogenesis and gametogenesis, fertilization, and embryogenesis and describe for the first time the developments of the gynoecium and the unique pollen tube pathway and fertilization; the term funiculogamy was proposed to define this type of pollen tube penetration. © 2016 by The University of Chicago. All rights reserved.

Two new species from north-western Argentina are described. The male of a new species of Alisotrichia is described and illustrated as A. benji. This represents the first record of the genus from north-western Argentina. The male and larva of a new species of Leucotrichia are described and illustrated as L. alisensis. The taxonomic positions of A. benji and L. alisensis are discussed. Hydroptila argentinica Flint, H. bidens Flint, Neotrichia gotera Flint and Oxyethyra parce Edwards & Arnold are newly recorded from Bolivia. Oxyethira ulmeri Mosely is recorded for the first time from north-western Argentina. New localities from north-western Argentina are recorded for Hydroptila bidens, Neotrichia elongata Flint and N. gotera. Illustrations of the males of species representing new records are included. © 2011 Taylor & Francis.

Bonanni P.S.,CONICET | Schrott G.D.,CONICET | Busalmen J.P.,CONICET
Biochemical Society Transactions | Year: 2012

The mechanism of electron transport in Geobacter sulfurreducens biofilms is a topic under intense study and debate. Although some proteins were found to be essential for current production, the specific role that each one plays in electron transport to the electrode remains to be elucidated and a consensus on the mechanism of electron transport has not been reached. In the present paper, to understand the state of the art in the topic, electron transport from inside of the cell to the electrode in Geobacter sulfurreducens biofilms is analysed, reviewing genetic studies, biofilm conductivity assays and electrochemical and spectroelectrochemical experiments. Furthermore, crucial data still required to achieve a deeper understanding are highlighted. ©The Authors Journal compilation ©2012 Biochemical Society.

Ortiz de la Plata G.B.,CONICET | Alfano O.M.,CONICET | Cassano A.E.,CONICET
Applied Catalysis B: Environmental | Year: 2010

A study has been conducted on the decomposition of 2-chlorophenol (2-CP) applying a heterogeneous Fenton reaction using goethite as catalyst at pH 3. The research was aimed at obtaining a workable kinetic expression apt for developing a kinetic model for scaling up purposes. Several aspects of the reaction have been described in the available literature but, for the moment, without a reasonable representation of the entire reaction behavior. In order to provide a more comprehensive and probable explanation of the whole observed performance, a set of experiments was carried out varying systematically all the significant variables. The proposal considers that the reaction is essentially a combination of four heterogeneous processes associated with one typical homogeneous Fenton reaction. Three of the surface reactions explain a very small iron leaching to the medium by a proton induced solubilization, a reductive dissolution reaction and a non-reductive iron release produced by detected 2-CP chemical decomposition byproducts, particularly, chlorohydroquinone (ClHQ) and oxalic acid (OxA). Iron concentration in the solution may be further increased in the final stages of the reaction after most of the 2-CP has been degraded, by the appearance of OxA that takes part in a third surface reaction. The fourth heterogeneous reaction rationalizes the unusual hydrogen peroxide consumption at high catalyst loadings. During the homogeneous reaction, the presence of ClHQ and ClBQ produces a homogeneous autocatalytic beneficial enhancement of the Fe3+ → Fe2+ transformation. Consequently, the existence of phenolic derivatives either in the mixture or as reaction byproducts produces a beneficial enhancement of the reaction rate. Very low iron leaching is required to produce the onset of the homogeneous Fenton reaction, which was shown to be strongly dependent upon the reaction temperature. All the experimental findings were satisfactorily described by a set of 19-step feasible reaction scheme. The process could be useful for the treatment of wastewaters containing pollutants with phenolic derivatives, as long as iron leaching remains within tolerable limits. © 2009 Elsevier B.V. All rights reserved.

Ortiz de la Plata G.B.,CONICET | Alfano O.M.,CONICET | Cassano A.E.,CONICET
Applied Catalysis B: Environmental | Year: 2010

The kinetics of the degradation of 2-chlorophenol (2-CP) employing both the heterogeneous Fenton and photo-Fenton reactions using goethite as the solid catalyst is studied. The photoreactor was irradiated with a 350-400 nm wavelength light. The kinetics is based on 19 steps of a combined heterogeneous-homogeneous mechanism derived for the thermal Fenton reaction [see companion article by the authors: Ortiz de la Plata et al. (2009)] [1]. For the photo-Fenton alternative, two more steps are needed. Some of the specific kinetic constants of the reaction scheme are approximately known. However, for the heterogeneous "thermal" Fenton reaction, three new unknown constants were required and were attained from experimental data obtained in this and the previous work. The parameters were (i) the reaction of the HO{radical dot} radical with 2-CP, (ii) the proton induced iron dissolution and (iii) the reductive induced iron dissolution [1]. In the case of the heterogeneous photo-Fenton reaction steps, the radiation field in the reacting system was described by solving the complete radiative transfer equation inside the reactor. With this purpose, the knowledge of the needed goethite optical properties were previously characterized [2]. Combining the dark and the irradiated experiments 21 kinetically consistent parameters were achieved for the proposal of a feasible mechanism. They are valid for both systems; making the two primary quantum yields of the photoreaction equal to zero, the "dark" Fenton reaction performance is properly described by the remaining 19 specific rate constants. These results are independent of the used experimental apparatus and can be safely used for scaling-up purposes within the range of the explored variables. © 2009 Elsevier B.V. All rights reserved.

A mathematical model to describe the amperometric response of a sandwich-type biosensor containing polyphenol oxidase as the recognition catalytic element is proposed. The model was solved numerically and the resulting nonlinear solution was used to simulate chronoamperometric curves as well as to estimate the concentration profiles of reagents and products of the enzymatic reaction within the sensor. Fromm's systematic method was applied to get a kinetic expression for the analysis of polyphenol oxidase enzymes. The simulated data are compared with curves corresponding to a biosensor prepared with an oxidase enzyme that reacts according to a ping-pong mechanism. Although in both cases oxygen is used as mediator of the enzymatic reaction, the electrochemical step can generate it back from the H2O2 released by enzymes such as glucose oxidase but it cannot do the same in the case of working with polyphenol oxidase. Most of the calculated profiles and related data are presented using dimensioned variables so that they can be directly compared with experimental results. Relevant parameters such as limit current, response-time, and sensitivity are analyzed as function of the thickness of membranes, concentration of enzyme and concentration of substrate. © 2014 Elsevier B.V. All rights reserved.

Bruls O.,University of Liège | Cardona A.,CONICET | Arnold M.,Martin Luther University of Halle Wittenberg
Mechanism and Machine Theory | Year: 2012

This paper studies a Lie group extension of the generalized-α time integration method for the simulation of flexible multibody systems. The equations of motion are formulated as an index-3 differential-algebraic equation (DAE) on a Lie group, with the advantage that rotation variables can be taken into account without the need of introducing any parameterization. The proposed integrator is designed to solve this equation directly on the Lie group without index reduction. The convergence of the method for DAEs is studied in detail and global second-order accuracy is proven for all solution components, i.e. for nodal translations, rotations and Lagrange multipliers. The convergence properties are confirmed by three benchmarks of rigid and flexible systems with large rotation amplitudes. The Lie group method is compared with a more classical updated Lagrangian method which is also formulated in a Lie group setting. The remarkable simplicity of the new algorithm opens interesting perspectives for real-time applications, model-based control and optimization of multibody systems. © 2011 Elsevier Ltd. All rights reserved.

Armentano M.G.,CONICET | Godoy D.,CONICET | Amandi A.A.,CONICET
Information Systems | Year: 2013

Nowadays, more and more users keep up with news through information streams coming from real-time micro-blogging activity offered by services such as Twitter. In these sites, information is shared via a followers/followees social network structure in which a follower receives all the micro-blogs from his/her followees. Recent research efforts on understanding micro-blogging as a novel form of communication and news spreading medium have identified three different categories of users in these systems: information sources, information seekers and friends. As social networks grow in the number of registered users, finding relevant and reliable users to receive interesting information becomes essential. In this paper we propose a followee recommender system based on both the analysis of the content of micro-blogs to detect users' interests and in the exploration of the topology of the network to find candidate users for recommendation. Experimental evaluation was conducted in order to determine the impact of different profiling strategies based on the text analysis of micro-blogs as well as several factors that allows the identification of users acting as good information sources. We found that user-generated content available in the network is a rich source of information for profiling users and finding like-minded people. © 2013 Elsevier Ltd. All rights reserved.

Camicia G.,Hospital Of Infecciosas Fj Muniz | Pozner R.,CONICET | De Larranaga G.,Hospital Of Infecciosas Fj Muniz
Shock | Year: 2014

Sepsis is the leading cause of death in critically ill patients in intensive care units. Early recognition of sepsis and proper therapy are essential to reduce patient mortality. Moreover, treatment options for this deleterious inflammatory response to infection are limited. Neutrophils play an essential role in the innate immune response, providing the first line of host defense. It has recently been shown that these cells can trap and kill microorganisms by releasing neutrophil extracellular traps (NETs) composed of chromatin and antimicrobial proteins. Although the beneficial role of NETs during infections has been demonstrated, there is increasing evidence that NETs and their components contribute to the pathogenesis of several diseases, including sepsis. The aim of this review was to summarize the current evidence implicating NETs, as well as their components, in the development of sepsis and to discuss their potential use as novel therapeutic targets and as prognostic markers in septic patients. Copyright © 2014 by the Shock Society.

Three different types of data sets, for which the uniquely most parsimonious tree can be known exactly but is hard to find with heuristic tree search methods, are studied. Tree searches are complicated more by the shape of the tree landscape (i.e. the distribution of homoplasy on different trees) than by the sheer abundance of homoplasy or character conflict. Data sets of Type 1 are those constructed by Radel et al. (2013). Data sets of Type 2 present a very rugged landscape, with narrow peaks and valleys, but relatively low amounts of homoplasy. For such a tree landscape, subjecting the trees to TBR and saving suboptimal trees produces much better results when the sequence of clipping for the tree branches is randomized instead of fixed. An unexpected finding for data sets of Types 1 and 2 is that starting a search from a random tree instead of a random addition sequence Wagner tree may increase the probability that the search finds the most parsimonious tree; a small artificial example where these probabilities can be calculated exactly is presented. Data sets of Type 3, the most difficult data sets studied here, comprise only congruent characters, and a single island with only one most parsimonious tree. Even if there is a single island, missing entries create a very flat landscape which is difficult to traverse with tree search algorithms because the number of equally parsimonious trees that need to be saved and swapped to effectively move around the plateaus is too large. Minor modifications of the parameters of tree drifting, ratchet, and sectorial searches allow travelling around these plateaus much more efficiently than saving and swapping large numbers of equally parsimonious trees with TBR. For these data sets, two new related criteria for selecting taxon addition sequences in Wagner trees (the "selected" and "informative" addition sequences) produce much better results than the standard random or closest addition sequences. These new methods for Wagner trees and for moving around plateaus can be useful when analyzing phylogenomic data sets formed by concatenation of genes with uneven taxon representation ("sparse" supermatrices), which are likely to present a tree landscape with extensive plateaus. © 2014 Elsevier Inc.

Chung C.,Konkuk University | Raingo J.,CONICET
Journal of Neurochemistry | Year: 2013

Central synapses operate neurotransmission in several modes: synchronous/fast neurotransmission (neurotransmitters release is tightly coupled to action potentials and fast), asynchronous neurotransmission (neurotransmitter release is slower and longer lasting), and spontaneous neurotransmission (where small amounts of neurotransmitter are released without being evoked by an action potential). A substantial body of evidence from the past two decades suggests that seemingly identical synaptic vesicles possess distinct propensities to fuse, thus selectively serving different modes of neurotransmission. In efforts to better understand the mechanism(s) underlying the different modes of synaptic transmission, many research groups found that synaptic vesicles used in different modes of neurotransmission differ by a number of synaptic proteins. Synchronous transmission with higher temporal fidelity to stimulation seems to require synaptotagmin 1 and complexin for its Ca2+ sensitivity, RIM proteins for closer location of synaptic vesicles (SV) to the voltage operated calcium channels (VGCC), and dynamin for SV retrieval. Asynchronous release does not seem to require functional synaptotagmin 1 as a calcium sensor or complexins, but the activity of dynamin is indispensible for its maintenance. On the other hand, the control of spontaneous neurotransmission remains less clear as deleting a number of essential synaptic proteins does not abolish this type of synaptic vesicle fusion. VGCC distance from the SV seems to have little control on spontaneous transmission, while there is an involvement of functional synaptic proteins including synaptotagmins and complexin. Recently, presynaptic deficits have been proposed to contribute to a number of pathological conditions including cognitive and mental disorders. In this review, we evaluate recent advances in understanding the regulatory mechanisms of synaptic vesicle dynamics and in understanding how different molecular substrates maintain selective modes of neurotransmission. We also highlight the implications of these studies in understanding pathological conditions. © 2013 International Society for Neurochemistry.

Mongiat L.A.,CONICET | Schinder A.F.,CONICET
Science | Year: 2014

Newly formed hippocampal neurons participate in the encoding of new memories in adult rodents, but too much neurogenesis may jeopardize memory retention.

Pacin M.,University of Buenos Aires | Legris M.,CONICET | Casal J.J.,University of Buenos Aires | Casal J.J.,CONICET
Plant Journal | Year: 2013

Shade-avoider plants typically respond to shade-light signals by increasing the rate of stem growth. CONSTITTUTIVE PHOTOMORPHOGENESIS 1 (COP1) is an E3 ligase involved in the ubiquitin labelling of proteins targeted for degradation. In dark-grown seedlings, COP1 accumulates in the nucleus and light exposure causes COP1 migration to the cytosol. Here, we show that in Arabidopsis thaliana, COP1 accumulates in the nucleus under natural or simulated shade, despite the presence of far-red light. In plants grown under white light, the transfer to shade-light conditions triggers an unexpectedly rapid re-accumulation of COP1 in the nucleus. The partial simulation of shade by lowering either blue or red light levels (maintaining far-red light) caused COP1 nuclear re-accumulation. Hypocotyl growth of wild-type seedlings is more sensitive to afternoon shade than to morning shade. A residual response to shade was observed in the cop1 mutant background, but these seedlings showed inverted sensitivity as they responded to morning shade and not to afternoon shade. COP1 overexpression exaggerated the wild-type pattern by enhancing afternoon sensitivity and making morning shade inhibitory of growth. COP1 nuclear re-accumulation also responded more strongly to afternoon shade than to morning shade. These results are consistent with a signalling role of COP1 in shade avoidance. We propose a function of COP1 in setting the daily patterns of sensitivity to shade in the fluctuating light environments of plant canopies. © 2013 John Wiley & Sons Ltd.

Journal of Physics Condensed Matter | Year: 2010

By combining analytical results and computer simulations, we studied the continuous theory of surface diffusion applied to the decay of periodic high-aspect-ratio patterned substrates. Our results show that, after a transient stage, and for a broad class of initial conditions, patterns adopt a 'universal' mathematically well-specified shape that depends on two coefficients. Moreover, we were able to determine the time-dependence of such coefficients, which enabled us to mathematically reconstruct the pattern's shape at any subsequent time. So, our analysis can be a useful predictive theoretical tool for the design and interpretation of experiments on thermal treatments of high-aspect-ratio patterns. © 2010 IOP Publishing Ltd.

Curatti L.,CONICET | Rubio L.M.,Technical University of Madrid
Plant Science | Year: 2014

Some regions of the developing world suffer low cereal production yields due to low fertilizer inputs, among other factors. Biological N2 fixation, catalyzed by the prokaryotic enzyme nitrogenase, is an alternative to the use of synthetic N fertilizers. The molybdenum nitrogenase is an O2-labile metalloenzyme composed of the NifDK and NifH proteins, which biosyntheses require a number of nif gene products. A challenging strategy to increase cereal crop productivity in a scenario of low N fertilization is the direct transfer of nif genes into cereals. The sensitivity of nitrogenase to O2 and the apparent complexity of nitrogenase biosynthesis are the main barriers identified so far. Expression of active NifH requires the products of nifM, nifH, and possibly nifU and nifS, whereas active NifDK requires the products of nifH, nifD, nifK, nifB, nifE, nifN, and possibly nifU, nifS, nifQ, nifV, nafY, nifW and nifZ. Plastids and mitochondria are potential subcellular locations for nitrogenase. Both could provide the ATP and electrons required for nitrogenase to function but they differ in their internal O2 levels and their ability to incorporate ammonium into amino acids. © 2014 Elsevier Ireland Ltd.

Biochimica et Biophysica Acta - Molecular and Cell Biology of Lipids | Year: 2010

The mammalian pineal gland is a prominent secretory organ with a high metabolic activity. Melatonin (N-acetyl-5-methoxytryptamine), the main secretory product of the pineal gland, efficiently scavenges both the hydroxyl and peroxyl radicals counteracting lipid peroxidation in biological membranes. Approximately 25% of the total fatty acids present in the rat pineal lipids are represented by arachidonic acid (20:4n-6) and docosahexaenoic acid (22:6n-3). These very long chain polyunsaturated fatty acids play important roles in the pineal gland. In addition to the production of melatonin, the mammalian pineal gland is able of convert these polyunsaturated fatty acids into bioactive lipid mediators. Lipoxygenation is the principal lipoxygenase (LOX) activity observed in the rat pineal gland. Lipoxygenation in the pineal gland is exceptional because no other brain regions express significant LOX activities under normal physiological conditions. The rat pineal gland expresses both 12- and 15-lipoxygenase (LOX) activities, producing 12- and 15-hydroperoxyeicosatetraenoic acid (12- and 15-HpETE) from arachidonic acid and 14- and 17-hydroxydocosahexaenoic acid (14- and 17-HdoHE) from docosahexaenoic acid, respectively. The rat pineal also produces hepoxilins via LOX pathways. The hepoxilins are bioactive epoxy-hydroxy products of the arachidonic acid metabolism via the 12S-lipoxygenase (12S-LOX) pathway. The two key pineal biochemical functions, lipoxygenation and melatonin synthesis, may be synergistically regulated by the status of n-3 essential fatty acids. © 2009 Elsevier B.V. All rights reserved.

Haberman M.A.,CONICET | Spinelli E.M.,CONICET
IEEE Transactions on Biomedical Circuits and Systems | Year: 2012

Single ended (SE) amplifiers allow implementing biopotential front-ends with a reduced number of parts, being well suited for preamplified electrodes or compact EEG headboxes. On the other hand, given that each channel has independent gain; mismatching between these gains results in poor common-mode rejection ratios (CMRRs) (about 30 dB considering 1% tolerance components). This work proposes a scheme for multichannel EEG acquisition systems based on SE amplifiers and a novel digital driven right leg (DDRL) circuit, which overcome the poor CMRR of the front-end stage providing a high common mode reduction at power line frequency (up to 80 dB). A functional prototype was built and tested showing the feasibility of the proposed technique. It provided EEG records with negligible power line interference, even in very aggressive EMI environments. © 2007-2012 IEEE.

Amodeo S.J.,CONICET | Chiacchiarini H.G.,CONICET | Oliva A.R.,CONICET
IEEE Transactions on Power Electronics | Year: 2012

The electromechanical interface is a synchronous machine, because its field winding permits direct management of the magnetization during speed variations. For systems with a common dc-link for the drive and excitation converters, the efficiency is increased if the excitation drive has boosting capability. It is shown that with the proposed control strategy the Z-source converter is suitable for this application, becoming a better alternative than the typically used buck converter. The Z-source converter, in combination with the proposed multiloop control law, can achieve the desired voltage reference swing and high-performance tracking. An analytical comparison between the dominant losses of the buck topology, typically used in FESS, and the Z-source converter shows that the latter has higher efficiency for this application. The parameters of the converter prototype were experimentally identified and used to implement the proposed controller. The control strategy uses the two duty cycles as manipulated variables, one to allow tracking fast changes in the reference signal and the other to adapt the system to the slow changes. The combined action on both inputs contribute to the compensation of the nonminimum phase response of the Z-converter. Experimental results show the potential of the controller for tracking typical FESS application waveforms. © 2006 IEEE.

Microfluidics and Nanofluidics | Year: 2010

Theoretical expressions of the flow rate, output pressure and thermodynamic efficiency of electrokinetic pumping of non-Newtonian fluids through cylindrical and slit microchannels are reported. Calculations are carried out in the framework of continuum fluid mechanics. The constitutive model of Ostwald-de Waele (power law) is used to express the fluid shear stress in terms of the velocity gradient. The resulting equations of flow rate and electric current are nonlinear functions of the electric potential and pressure gradients. The fact that the microstructure of non-Newtonian fluids is altered at solid-liquid interfaces is taken into account. In the case of fluids with wall depletion, both the output pressure and efficiency are found to be several times higher than that obtained with simple electrolytes under the same experimental conditions. Apart from potential applications in electrokinetic pumps, these predictions are of interest for the design of microfluidic devices that manipulate non-Newtonian fluids such as polymer solutions and colloidal suspensions. From a more fundamental point of view, the paper discusses a relevant example of nonlinear electrokinetics. © 2009 Springer-Verlag.

Bianchi N.O.,CONICET
Cytogenetic and Genome Research | Year: 2010

The relevant role of mitochondrial mutations in cancer is the most frequent conclusion found in most early publications on the subject. However, it is now clear that this assumption was in many cases based on circumstantial or even flawed evidence. Presently, we know that normal mitochondria structure and functions depend on the concerted interaction between mitochondrial (mt)-genes and different groups of nuclear genes. Thus, somatic mutations of mt- or nuclear genes controlling mitochondrial physiology would influence the cancer transformation process through a disruption of nuclear↔mitochondrial gene interactions. In this regard, somatic mt-mutations influencing carcinogenesis have been detected in preneoplastic lesions. Furthermore, an abnormal respiration process with the subsequent increase in reactive oxygen species production seems to be one of the basic mechanisms favoring oncogenesis. Many mt-genes exhibit inherited polymorphisms associated with their mitochondrial phylogenetic history. In this report we shall summarize data showing that some of these ethnic mt- mutations may increase or alternatively decrease the susceptibility to various forms of malignancy. The interference of mt-mutations with anticancer therapies and the use of body fluids for the analysis of mt-mutations to obtain tumor samples avoiding invasive techniques are two promising fields to be further investigated. Copyright © 2010 S. Karger AG, Basel.

Cuadrado-Laborde C.,CONICET
IEEE Photonics Technology Letters | Year: 2010

We numerically demonstrate that an asymmetrical fiber Bragg grating of uniform-period operated in reflection can provide the required spectral response for implementing an all-optical fractional Hubert transformer. The device shows a good accuracy calculating the fractional Hilbert transform of the complex field of some typical input optical waveforms. The sensibility of the proposed device under different conditions was also analyzed. © 2009 IEEE.

We obtain for the two-phase Lamé-Clapeyron-Stefan problem for a semiinfinite material an equivalence between the temperature and convective boundary conditions at the fixed face in the case that an inequality for the convective transfer coefficient is satisfied. Moreover, an inequality for the coefficient which characterizes the solid-liquid interface of the classical Neumann solution is also obtained. This inequality must be satisfied for data of any phase-change material, and as a consequence the result given in Tarzia, Quart. Appl. Math., 39 (1981), 491-497 is also recovered when a heat flux condition was imposed at the fixed face.