Buenos Aires, Argentina
Buenos Aires, Argentina

The University of Buenos Aires is the largest university in Argentina and the second largest university by enrollment in Latin America. Founded on August 12, 1821 in the city of Buenos Aires, it consists of 13 departments, 6 hospitals, 10 museums and is linked to 4 high schools: Colegio Nacional de Buenos Aires, Escuela Superior de Comercio Carlos Pellegrini, Instituto Libre de Segunda Enseñanza and Escuela de Educación Técnica Profesional en Producción Agropecuaria y Agroalimentaria.Entry to any of the available programmes of study in the university is open to anyone with a secondary school degree; in most cases, students who have successfully completed high school must pass a first year called CBC, which stands for Ciclo Básico Común . Only upon completion of this first year may the student enter the chosen school; until then, they must attend courses in different buildings, and have up to 3 years to finish the 6 or 7 subjects assigned in two groups of 3 or 4. Each subject is of one semester duration . If someone passes all 6 subjects in their respective semester, the CBC will take only one year. Potential students of economics, instead, take a 2-year common cycle, the "CBG" , comprising 12 subjects.The UBA has no central campus. A centralized Ciudad Universitaria was started in the 1960s, but contains only two schools, with the others at different locations in Buenos Aires. Access to the university is free of charge for everyone, including foreigners. However, the postgraduate programs charge tuition fees that can be covered with research scholarships for those students with outstanding academic performance.The university has produced more Nobel Prize laureates than any other Spanish-speaking institution. It is currently the best ranked Argentine university in college and university rankings, present at number 197 of the Top Universities 2008 and at number 151-200 of the 2010 Shanghai Jiao Tong University ranking. According to the 2010 University Ranking by Academic Performance , the university is the best in Argentina and the 247th in the world, and, according to TopUniversities, it is the 46th best university in the world taking into account employer reputation. Wikipedia.

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Mindlin G.B.,University of Buenos Aires
Journal of Statistical Mechanics: Theory and Experiment | Year: 2017

Birdsong is an active field of research in neuroscience, since songbirds learn their songs through a process similar to that followed by humans during vocal learning. Moreover, many of the vocalizations produced by birds are quite complex. Since the avian vocal organ is nonlinear, it is sensible to explore how much of that complexity is due to the neural instructions controlling the vocal organ, and how much to its nonlinear nature. In this work we first review some of the work carried out in the last years to address this problem, and then we discuss the existence of noisy sound sources in the avian vocal organ. We show that some spectral features of the song produced by the Zebra finch (one of the most widely studied species) can only be explained when vortex sound is taken into account. © 2017 IOP Publishing Ltd and SISSA Medialab srl.

Salvo G.,Edenor S.A. | Salvo G.,University of Buenos Aires | Piacquadio M.N.,University of Buenos Aires
Energy for Sustainable Development | Year: 2017

Electrical utilities need to plan their investments in substations and networks to meet future customer demand, by predicting the spatial load growth and its time trend. Several techniques are currently in use to do that, such as trending analysis or simulation methods. To study the electricity demand we used multifractal analysis. A fractal is an object whose irregularities are not smooth and have some self-similarity at different scales. If the fractal does not have strict self-similarity, we could break such fractality, if it really exists in the system, in a spectrum of sub fractals which have a self-similar structure, performing the so-called multifractal spectral analysis. Multifractal spectral analysis has been already applied to study the morphology and population growth of cities. Because electricity demand can be related to demographics of cities, it is possible to consider the hypothesis that multifractal spectral decomposition can be applied to analyze electricity demand. A variety of multifractal analyses were performed on real data from the customer demand of an electrical utility. The results show that the analyzed electricity demand is split into clear and interesting two-multifractal distribution with properties not found yet in the literature on the subject. This type of multifractal analysis could lead the way to improved spatial demand forecasting methods. © 2017 International Energy Initiative

Palottini F.,University of Buenos Aires | Manrique G.,University of Buenos Aires
Physiological Entomology | Year: 2016

Adults of the Chagas disease vector Triatoma infestans Klug (Hemiptera: Reduviidae: Triatominae), possess paired exocrine glands: the metasternal and Brindley's glands. Both glands are discharged by disturbed adults, releasing an alarm pheromone that elicits an escape response of larvae. The present study analyzes the individual (or combined) effects of some of the volatiles of the whole pheromone blend released under disturbance, searching for active compounds and for possible interactions (e.g. synergism, additive effects) between them. Using an experimental arena, different doses of components emitted by disturbed adults are tested against larvae. Larvae show escape responses to some of the acids, as well as to one alcohol, but no response to ketones. This is observed with certain doses of compounds from Brindley's glands (isobutyric, butyric and acetic acid; 2-methyl-1-butanol), although the compounds tested in the present study that are produced by metasternal glands are shown to evoke random responses, suggesting that mainly Brindley's glands are involved in the alarm context. Two combinations of two individually repellent compounds (2-methyl-1-butanol with acetic or isobutyric acid) evoke escape responses, although other combinations make the individual effect disappear. A different mixture of two individually repellent compounds (butyric and isobutyric acid) evokes attraction, although these are also host odours. The potential use of the active compounds released by disturbed adults to monitor triatomine populations is discussed. © 2016 The Royal Entomological Society

G. Cionco R.,University of Buenos Aires | W.-H. Soon W.,Harvard - Smithsonian Center for Astrophysics
Earth-Science Reviews | Year: 2017

The aim of this paper is to provide geoscientists with the most accurate set of the Earth's astro-climatic parameters and daily insolation quantities, able to describe the Short-Term Orbital Forcing (STOF) as represented by the ever-changing incoming solar radiation. We provide an updated review and a pragmatic tool/database using the latest astronomical models and orbital ephemeris, for the entire Holocene and 1 kyr into the future. Our results are compared with the most important database produced for studying long-term orbital forcing showing no systematic discrepancies over the full thirteen thousand years period studied. Our detailed analysis of the periods present in STOF, as perturbed by Solar System bodies, yields a very rich dynamical modulation on annual-to-decadal timescales when compared to previous results. In addition, we addressed, for the first time, the error committed considering daily insolation as a continuous function of orbital longitudes with respect to the nominal values, i.e., calculating the corresponding daily insolation with orbital longitudes tabulated at noon. We found important relative differences up to ± 5%, which correspond to errors of 2.5 W m −2 in the daily mean insolation, for exactly the same calendar day and set of astro-climatic parameters. This previously unrecognized error could have a significant impact in both the initial and boundary conditions for any climate modeling experiment. © 2017 Elsevier B.V.

Rodriguez N.,University of Buenos Aires | Silveira R.I.,University of Buenos Aires
GIS: Proceedings of the ACM International Symposium on Advances in Geographic Information Systems | Year: 2016

The Delaunay triangulation is the standard choice for building triangulated irregular networks (TINs) to represent terrain surfaces. However, the Delaunay triangulation is based only on the 2D coordinates of the data points, ignoring their elevation. It has long been recognized that sometimes it may be beneficial to use other, non-Delaunay, criteria to build TINs. Data-dependent triangulations were introduced decades ago to address this. However, they are rarely used in practice, mostly because the optimization of datadependent criteria often results in triangulations with many thin and elongated triangles. Recently, in the field of computational geometry, higher order Delaunay triangulations (HODTs) were introduced, trying to tackle both issues at the same time-data-dependent criteria and good triangle shape. Nevertheless, most previous studies about them have been limited to theoretical aspects. In this work we present the first extensive experimental study on the practical use of HODTs, as a tool to build data-dependent TINs. We present experiments with two USGS terrains that show that HODTs can give significant improvements over the Delaunay triangulation for the criteria identified as most important for data-dependent triangulations. The resulting triangulations have data-dependent values comparable to those obtained with pure data-dependent approaches, without compromising the shape of the triangles, and are faster to compute. © 2016 ACM.

Smucler E.,University of Buenos Aires | Yohai V.J.,University of Buenos Aires
Computational Statistics and Data Analysis | Year: 2017

Penalized regression estimators are popular tools for the analysis of sparse and high-dimensional models. However, penalized regression estimators defined using an unbounded loss function can be very sensitive to the presence of outlying observations, especially to high leverage outliers. The robust and asymptotic properties of ℓ1-penalized MM-estimators and MM-estimators with an adaptive ℓ1 penalty are studied. For the case of a fixed number of covariates, the asymptotic distribution of the estimators is derived and it is proven that for the case of an adaptive ℓ1 penalty, the resulting estimator can have the oracle property. The advantages of the proposed estimators are demonstrated through an extensive simulation study and the analysis of real data sets. The proofs of the theoretical results are available in the Supplementary material to this article (see Appendix A). © 2017 Elsevier B.V.

In this article we analyze notions about healthy food and the perceptions of risks related to industrialized foodstuffs within a group of young and middle-aged females and males who belong to the middle class and live in the Metropolitan Area of Buenos Aires. Data come from eight focus groups that were carried out in 2013. The study shows that the participants of the focus group have incorporated scientific-nutritional knowledge into their conceptions of healthy food. However, few discuss the risks of industrialized food beyond the growing public attention regarding trans fats and salt content. Although organic foods are positively valued, participants object to their high cost and the location of their commercialization. We show how in their food practices, the participants of the focus groups weigh their concern about health against other priorities such as costs, convenience, aesthetics, pleasure and sociability.

Carballo R.R.,University of Buenos Aires | Rezzano I.N.,University of Buenos Aires
Electroanalysis | Year: 2017

The electropolymerization of Ni(II) Protoporphyrin (polyNiPP) onto glassy carbon electrodes is performed in different experimental conditions, varying the supporting electrolytes, solvent, and oxidative potentials. The AFM images show different average thickness for each polymer, polyNiPP(TBAP) (0.6 μm) and polyNiPP(LiClO4) (0.1μm). The polyNiPP(LiClO4) describes a straight line plot of EMF versus log (C) for NO2 -, with the slope of 37 mV per concentration decade while the same film is not sensitive to the thiocyanate concentration. For polyNiPP(TBAP) the slope for thiocyanate progressively increase when is oxidized in aqueous solution. A sub-Nernstian response (59 mV /decade) is obtained at 1000 mV. The Nyquist plots confirm that the method of preparation establishes the properties of films related to the movement of the ions. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Trainotti V.,University of Buenos Aires
2016 IEEE Global Electromagnetic Compatibility Conference, GEMCCON 2016 | Year: 2016

A method for calculating and measuring antenna gain and factor over perfect ground is presented. The EMC antenna factor is used to determine the spurious electric field of device under evaluation. The radio link employed to calibrate the receiving antenna gain and factor will produce completely different values for the transmitting and receiving antennas, and the principle of reciprocity does not hold true, in this particular case, even if both antennas are identical. © 2016 IEEE.

Gonzalez-Vicente A.,Case Western Reserve University | Gonzalez-Vicente A.,University of Buenos Aires | Garvin J.L.,Case Western Reserve University
Antioxidants | Year: 2017

Reactive oxygen species (ROS) are oxygen-containing molecules naturally occurring in both inorganic and biological chemical systems. Due to their high reactivity and potentially damaging effects to biomolecules, cells express a battery of enzymes to rapidly metabolize them to innocuous intermediaries. Initially, ROS were considered by biologists as dangerous byproducts of respiration capable of causing oxidative stress, a condition in which overproduction of ROS leads to a reduction in protective molecules and enzymes and consequent damage to lipids, proteins, and DNA. In fact, ROS are used by immune systems to kill virus and bacteria, causing inflammation and local tissue damage. Today, we know that the functions of ROS are not so limited, and that they also act as signaling molecules mediating processes as diverse as gene expression, mechanosensation, and epithelial transport. In the kidney, ROS such as nitric oxide (NO), superoxide (O2 −), and their derivative molecules hydrogen peroxide (H2O2) and peroxynitrite (ONO2 −) regulate solute and water reabsorption, which is vital to maintain electrolyte homeostasis and extracellular fluid volume. This article reviews the effects of NO, O2 −, ONO2 −, and H2O2 on water and electrolyte reabsorption in proximal tubules, thick ascending limbs, and collecting ducts, and the effects of NO and O2 − in the macula densa on tubuloglomerular feedback. © 2017 by the authors. Licensee MDPI, Basel, Switzerland.

Paz Volker M.,University of Buenos Aires
Journal of Vocational Rehabilitation | Year: 2013

Argentina has shown a growing interest from the different sectors of society towards the welfare of people with disabilities. Specifically in the labor area, due to the alarming data that 75% ofworking age people with disabilities are unemployed and according to the tenets of the International Convention on the Rights of People with Disabilities (U.N.), the Argentina government decided to develop and reactivate policies to address this situation. The business sector also shows more concern about the inclusion of people with disabilities in their workforce under Corporate Social Responsibility policies. These institutions are only beginning to regard supported employment as a system of labor inclusion in the competitive job market for people with disabilities. There are challenges ahead to ensure full citizenship of people with disabilities, in which the inclusion in the open labor market takes an essential role, and supported employment is emerging to address them. © 2013 - IOS Press and the authors.

Vila A.R.,University of Buenos Aires
ACM International Conference Proceeding Series | Year: 2015

The aim of the present paper is to study the role of the digital publishing industry in the context of the transposition into digital format of titles of a Latin American and Caribbean literary corpus. The main conclusions are articulated in the design of a corpus comprising titles and authors that Harold Bloom labels as a Latin American segment of the Western canon [1], in addition to those segments provided by feminist, queer, postcolonial, and/or decolonization critical theories; and, on the other hand, some of the strategies devised by major e-book retailers and digital libraries in order to offer transposed literature in digital format. © 2015 ACM.

Schavelzon D.,University of Buenos Aires
African and Black Diaspora | Year: 2014

Images of the Retiro slave market in Buenos Aires had never been seen previously and the possibility of excavating the site has long gone. The discovery of etchings of the underground cellars in 2010 of the Bieckert Brewery, which occupied the site years later, has made it possible to see the nature of the market and understand the functioning of the construction that preceded the brewery. This market was unique in the city in that it functioned almost underground. The issue of the presence of the African population in Buenos Aires has had a great impact on archaeology. All information regarding the black population's material culture and architectural places, whether made by them or for them, is important; such is the case here of accessing a system of vaulted subterranean constructions quite different from the city's other architecture. © 2014 © 2014 Taylor & Francis.

Rolhauser A.G.,National University of San Juan | Rolhauser A.G.,University of Buenos Aires | Pucheta E.,National University of San Juan
Ecology | Year: 2017

How plant functional traits (e.g., seed mass) drive species abundance within communities remains an unsolved question. Borrowing concepts from natural selection theory, we propose that trait-abundance relationships can generally correspond to one of three modes of trait selection: directional (a rectilinear relationship, where species at one end of a trait axis are most abundant), stabilizing (an n-shaped relationship), and disruptive (a u-shaped relationship). Stabilizing selection (i.e., the functional convergence of abundant species) would result from positive density-dependent interactions (e.g., facilitation) or due to generalized trade-offs in resource acquisition/use, while disruptive selection (i.e., the divergence of abundant species) would result from negative density-dependent interactions (e.g., competition) or due to environmental heterogeneity. These selection modes can be interpreted as proxies for community-level trait-fitness functions, which establish the degree to which traits are truly "functional". We searched for selection modes in a desert annual-plant community in Argentina (which was divided into winter and summer guilds) to test the hypothesis that the relative importance of disruptive mechanisms (competition, disturbances) decreases with the increase of abiotic stress, a stabilizing agent. Average density was analyzed as a function of eight traits generally linked to resource acquisition and competitive ability (maximum plant height, leaf size, specific leaf area, specific root length), resource retention and stress tolerance (leaf dissection, leaf dry matter content, specific root volume), and regeneration (seed mass) using multiple quadratic-regression models. Trait selection was stabilizing and/or directional when the environment was harshest (winter) and disruptive and/or directional when conditions were milder (summer). Selection patterns differed between guilds for two important traits: plant height and seed mass. These results suggest that abiotic stress may drive within-community functional convergence independently of the trait considered, opposing the view that some traits may be inherently convergent while others divergent. Our quadratic model-based approach provides standardized metrics of both linear and nonlinear selection that may allow simple comparisons among communities subjected to contrasting environmental conditions. These concepts, rooted in natural selection theory, may clarify the functional link between traits and species abundance, and thus help untangle the contributions of deterministic and stochastic processes on community assembly. © 2016 by the Ecological Society of America.

Graff P.,University of Buenos Aires | Aguiar M.R.,University of Buenos Aires
Ecology | Year: 2017

A proposed refinement to the stress-gradient hypothesis requires consideration of the strategies of the interacting species and the characteristics of the stress factors. While the strength and direction of these interactions can be predicted for different ecosystems, this idea remains largely untested in the field. We performed a manipulative field experiment complemented with a descriptive study to test the predictions in a natural setting that represents the extreme end of a precipitation gradient. There, wind driven desiccation and water availability are the main stressors (non-resource and resource-based stresses, respectively). We evaluated the interaction between the shrub and grasses that are dominant in the Patagonian steppe. The species had differences in morpho-functional traits and drought tolerance that fit into the C-S axis of Grime's strategies. We experimentally separated root zones to limit direct competition for soil moisture and reduce the resource-based stress on grasses. We also manipulated the distance to shrubs to evaluate non-resource stress amelioration by canopies (e.g., sun and wind) on grasses. Finally, we evaluated the distribution of naturally established C and S grasses in the neighborhood of C and S shrubs to infer process-pattern relationships. Our growth data coincide to a large degree to the predictions. We found positive effects on the growth of beneficiaries when stress was non-resource based and when strategies differed (i.e., Cshrub-Sgrass and Sshrub-Cgrass). We also found strong negative effects when the abiotic stress was driven by water, particularly on C grasses. Additionally, shrubs only increased the survival of grasses when strategies differed (i.e., Cshrub-Sgrass and Sshrub-Cgrass). Our manipulative and descriptive study supported previous results that showed that stress-tolerant species are important for the persistence of competitive species at high stress. While the applicability and generality of these predictions remains to be tested with more field experiments, some ecological factors, such as stress types and species traits, can explain much of the variation in how dominant shrubs and grasses interact in this extreme arid environment. Moreover, this framework could be extended to specifically test the importance of facilitation under different levels of stress. © 2016 by the Ecological Society of America.

Virasoro M.A.,University of Buenos Aires
International Journal of Modern Physics A | Year: 2017

Abdus Salam was a great man in more than one dimension. The conception and building of the ICTP system required much more than the intelligence of a great scientist. I will stress those other facets that made him such a unique personality: the optimism that coloured his views about men and women, his love for his people and his commitment to the less favoured peoples of the world and a crucial ingredient, his deep and complex sense of ethical values that pushed him towards engagement in the political reality. Endowed with a formidable power of persuasion and a healthy lack of respect for norms or rules that are not based on justice he made a big difference on many of us and will remain as an icon for future generations. I will also describe the final touches that Salam's collaborators and successors had to add to keep his heritage flourishing. © 2017 World Scientific Publishing Company.

Corach J.,University of Buenos Aires | Sorichetti P.A.,University of Buenos Aires | Romano S.D.,University of Buenos Aires
Fuel | Year: 2017

The relative permittivity of diesel fossil fuel and blends with biodiesel from soybean, in the full range from pure diesel to 100% biodiesel, was determined at temperatures between 298.0 K and 333.0 K (controlled within ±0.1 K), using an airtight cell. Measurements were made in the frequency range from 1 kHz to 100 kHz; this frequency range is suitable for the use of low-cost, portable equipment and also for the development of automotive sensors. The relative uncertainty of the measurements was below 1%. Experimental values of permittivity were satisfactorily fitted to a simple model as a function of temperature and composition. The RMS uncertainty of the fitting was 1.2%. The model parameters were determined from experimental results and verified by multiple regression analysis, with very good agreement. In addition, a model was proposed to estimate the composition of diesel/biodiesel blends from permittivity and temperature measurements. The parameters of the model were obtained by a multiple regression analysis; the RMS uncertainty of the composition estimation was below 2.5%. The results presented in this work describe accurately the dependence of the permittivity of diesel fuel with temperature and also validate and extend previously reported models for biodiesel-rich blends with diesel fossil fuel, allowing the estimation in the full composition range with good accuracy. © 2016 Elsevier Ltd

Montanari C.C.,University of Buenos Aires | Dimitriou P.,International Atomic Energy Agency
Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms | Year: 2017

The aim of this work is to present an overview of the state of art of the energy loss of ions in matter, based on the new developments in the stopping power database of the International Atomic Energy Agency (IAEA). This exhaustive collection of experimental data, graphs, programs and comparisons, is the legacy of Helmut Paul, who made it accessible to the global scientific community, and has been extensively employed in theoretical and experimental research during the last 25. years. The field of stopping power in matter is evolving, with new trends in materials of interest, including oxides, nitrides, polymers, and biological targets. Our goal is to identify areas of interest and emerging data needs to meet the requirements of a continuously developing user community. © 2017.

Oestreicher V.,University of Buenos Aires | Jobbagy M.,University of Buenos Aires | Jobbagy M.,Centro Interdisciplinario Of Nanociencia Y Nanotecnologia
Chemical Communications | Year: 2017

Highly crystalline HKUST-1 and COK-16-like phases were obtained based on a mild in situ alkalinization one-pot epoxide driven method. A slurry composed of finely ground trimesic acid, H3BTC, dispersed in a CuCl2 aqueous solution quantitatively developed well crystallized HKUST-1 after the addition of propylene oxide. The use of solid H3BTC ensures a low concentration of free linker, favoring crystalline growth over the precipitation of amorphous or metastable impurities. An extreme space-time yield of 2.1 × 105 kg m-3 day-1 was reached, with no linker excess and minimum use of solvent. The method was equally efficient in the achievement of pure NENU/COK-16 phases, containing [PW12O40]3-, [PMo12O40]3- and [SiMo12O40]4- polyoxometalates. © The Royal Society of Chemistry.

Fernandez S.,University of Buenos Aires | Cordoba M.,University of Buenos Aires
Animal Reproduction Science | Year: 2017

Hyaluronic acid, as well as heparin, is a glycosaminoglycan present in the female genital tract of cattle. The aim of this study was to evaluate oxidative metabolism and intracellular signals mediated by a membrane-associated adenylate cyclase (mAC), in sperm capacitation with hyaluronic acid and heparin, in cryopreserved bull sperm. The mAC inhibitor, 2′,5′-dideoxyadenosine, was used in the present study. Lactate dehydrogenase (LDH) and creatine kinase (CK) activities and lactate concentration were determined spectrophotometrically in the incubation medium. Capacitation and acrosome reaction were evaluated by chlortetracycline technique, while plasma membrane and acrosome integrity were determined by trypan blue stain/differential interference contrast microscopy. Heparin capacitated samples had a significant decrease in LDH and CK activities, while in hyaluronic acid capacitated samples LDH and CK activities both increased compared to control samples, in heparin and hyaluronic acid capacitation conditions, respectively. A significant increase in lactate concentration in the incubation medium occurred in hyaluronic acid-treated sperm samples compared to heparin treatment, indicating this energetic metabolite is produced during capacitation. The LDH and CK enzyme activities and lactate concentrations in the incubation medium were decreased with 2′,5′-dideoxyadenosine treatment in hyaluronic acid samples. The mAC inhibitor significantly inhibited heparin-induced capacitation of sperm cells, but did not completely inhibit hyaluronic acid capacitation. Therefore, hyaluronic acid and heparin are physiological glycosaminoglycans capable of inducing in vitro capacitation in cryopreserved bull sperm, stimulating different enzymatic pathways and intracellular signals modulated by a mAC. Hyaluronic acid induces sperm capacitation involving LDH and CK activities, thereby reducing oxidative metabolism, and this process is mediated by mAC. © 2017 Elsevier B.V.

Galvez R.H.,University of Buenos Aires
Scientometrics | Year: 2017

Author self-citation is a practice that has been historically surrounded by controversy. Although the prevalence of self-citations in different scientific fields has been thoroughly analysed, there is a lack of large scale quantitative research focusing on its usefulness at guiding readers in finding new relevant scientific knowledge. In this work we empirically address this issue. Using as our main corpus the entire set of PLOS journals research articles, we train a topic discovery model able to capture semantic dissimilarity between pairs of articles. By dividing pairs of articles involved in intra-PLOS citations into self-citations (articles linked by a cite which share at least one author) and non-self-citations (articles linked by a cite which share no author), we observe the distribution of semantic dissimilarity between citing and cited papers in both groups. We find that the typical semantic distance between articles involved in self-citations is significantly smaller than the observed one for articles involved in non-self-citations. Additionally, we find that our results are not driven by the fact that authors tend to specialize in particular areas of research, make use of specific research methodologies or simply have particular styles of writing. Overall, assuming shared content as an indicator of relevance and pertinence of citations, our results indicate that self-citations are, in general, useful as a mechanism of knowledge diffusion. © 2017 Akadémiai Kiadó, Budapest, Hungary

Richarte M.G.,Federal University of Paraná | Richarte M.G.,University of Buenos Aires | Kremer G.M.,Federal University of Paraná
European Physical Journal C | Year: 2017

We present a model of inflation where the inflaton is accommodated as a phantom field which exhibits an initial transient pole behavior and then decays into a quintessence field which is responsible for a radiation era. We must stress that the present unified model only deals with a single field and that the transition between the two eras is achieved in a smooth way, so the model does not suffer from the eternal inflation issue. We explore the conditions for the crossing of the phantom divide line within the inflationary era along with the structural stability of several critical points. We study the behavior of the phantom field within the slow-climb approximation along with the necessary conditions to have sufficient inflation. We also examine the model at the level of classical perturbations within the Newtonian gauge and determine the behavior of the gravitational potential, contrast density and perturbed field near the inflation stage and the subsequent radiation era. © 2017, The Author(s).

Bianco A.M.,University of Buenos Aires | Spano P.M.,University of Buenos Aires
Computational Statistics and Data Analysis | Year: 2017

In many applications of regression analysis, there are covariates that are measured with errors. A robust family of estimators of the parametric and nonparametric components of a structural partially linear errors-in-variables model is introduced. The proposed estimators are based on a three-step procedure where robust orthogonal regression estimators are combined with robust smoothing techniques. Under regularity conditions, it is proved that the resulting estimators are consistent. The robustness of the proposal is studied by means of the empirical influence function when the linear parameter is estimated using the orthogonal M-estimator. A simulation study allows to compare the behaviour of the robust estimators with their classical relatives and a real example data is analysed to illustrate the performance of the proposal. © 2016 Elsevier B.V.

The structural study of the petrophysical characteristics and the spatial arrangement of the fracturing in the exposed sedimentary rocks along the eastern edge of the Sierras Australes de Buenos Aires is the main objective of this work. These outcrops correspond to the Tunas Formation of the Pillahuincó Group (upper Paleozoic), being the closest and correlated with the sedimentary sequences located in the adjacent foreland Claromecó basin. According to available subsurface information the paleozoic sequences have potential hydrocarbon generation from the pelitic levels and coals swarms that could be source rocks placed on reservoirs levels with adequate porosity to become conventional and other with fractured levels of unconventional. Structural diagrams obtained from themesotectonic 1.134 data can recognize a responsible stressfield whose maximum principal stress was placed with NE-SW direction. The potential types of discontinuities able to improve the petrophysical properties of reservoir fluids in the adjacent Claromecó basin are the following fractures: 1) parallel to the stratification, 2) coincident with the cleavage axial plane, 3) dilatant filled by quartz and4) subvertical shear fractures. In the case of interventions of potential reservoirs made from exploration and / or producers wells, they should be preferable directed towards the eastern flanks of the anticlinal structures and close to azimuth N 130°. © 2016, Asociacion Geologica Argentina. All rights reserved.

Pigozzi M.I.,University of Buenos Aires
Cytogenetic and genome research | Year: 2016

The cytological analysis of meiotic chromosomes is an exceptional tool to approach complex processes such as synapsis and recombination during the division. Chromosome studies of meiosis have been especially valuable in birds, where naturally occurring mutants or experimental knock-out animals are not available to fully investigate the basic mechanisms of major meiotic events. This review highlights the main contributions of synaptonemal complex and lampbrush chromosome research to the current knowledge of avian meiosis, with special emphasis on the organization of chromosomes during prophase I, the impact of chromosome rearrangements during meiosis, and distinctive features of the ZW pair. © 2016 S. Karger AG, Basel.

Mastaglia S.,University of Buenos Aires
Acta Bioquimica Clinica Latinoamericana | Year: 2016

Age-related sarcopenia is a condition which typically shows a decline in muscle mass and strength due to multifactorial causes. Bones and muscles are two interrelated tissues. The mechanical forces applied on bones are those derived from muscle contraction, conditioning bone properties, such as mass, size, shape and architecture. Therefore, the decline of muscle mass and strength would lead to a decrease in bone quality and quantity resulting in bone frailty. For this reason, sarcopenia is a condition that increases the risk of suffering falls and fractures in older adults. Currently, osteosarcopenia is the term used to identify those older adults with a greater risk of fractures due to bone frailty; however, a consensus of the medical community is needed for developing diagnostic criteria which makes it possible to identify patients with a high risk of developing osteoporotic fractures, to perform adequate therapeutic interventions and to improve the quality of life of older adults.

Mastaglia S.,University of Buenos Aires
Acta Bioquimica Clinica Latinoamericana | Year: 2016

Periostin is a non-collagenous protein expressed mainly in the periosteum, which has an important role during embryonic bone formation but also when repairing bone lesions or metabolic bone diseases. In the first case, when healing fractures and during experimental animal models, a periostin increased expression has been observed immediately after fractures. These findings suggest that periostin may play an important role in periosteal callus formation during the early stage of fracture healing. In benign bone diseases, like fibrous dysplasia, the periostin over-expression was observedin the fibrous component lesion. So, this protein could be detected by immune histochemical technique in histopathology studies. Periostin is a soluble factor, which can be detected in peripheral blood. In recent years, several immunoassays have been developed, though the main limiting factor is the detection of all molecule circulating isoforms, without providing bone specificity. Development of new immunoassays with greater specificity and sensibility than the current ones is crucial to the research concerning the potential of periostin as a biomarker of periosteal metabolism, bone quality and resistance.

Osman M.,University of Buenos Aires | Alvarez M.S.,University of Buenos Aires
Climate Dynamics | Year: 2017

The prediction skill of subseasonal forecast models is evaluated for a strong and long-lasting heat wave occurred in December 2013 over Southern South America. Reforecasts from two models participating in the WCRP/WWRP Subseasonal to Seasonal project, the Bureau of Meteorology POAMA and Beijing Climate Center model BCC-CPS were considered to evaluate their skill in forecasting temperature and circulation anomalies during that event. The POAMA reforecast of 32-member ensemble size, initialized every five days, and BCC-CPS reforecast of 4-member ensemble size for the same date of POAMA plus the previous 4 days were considered. Weekly ensemble-mean forecasts were computed with leadtimes from 2 days up to 24 days every 5 days. Weekly anomalies were calculated for observations from 13th of December to 31st of December 2013. Anomalies for both observations and reforecast were calculated with respect to their own climatology. Results show that the ensemble mean warm anomalies forecasted for week 1 and 2 of the heat wave resulted more similar to the observations for the POAMA model, especially for longer leads. The BCC-CPS performed better for leads shorter than 7 (14) for week 1 (2). For week 3 the BCC-CPS outperformed the POAMA model, particularly at shorter leads, locating more accurately the maxima of the anomalies. In a probabilistic approach, POAMA predicted with a higher chance than BCC-CPS the excess of the upper tercile of temperature anomalies for almost every week and lead time. The forecast of the circulation anomalies over South America could be used to explain the location of the highest temperature anomalies. In summary, for this case, models skill in forecasting surface temperature in a context of a heat wave resulted moderate at lead times longer than the fortnight. However, this study is limited to model-to-model analysis and a multi-model ensemble strategy might increase the skill. © 2017 Springer-Verlag Berlin Heidelberg

Cohen I.M.,University of Buenos Aires
Journal of Radioanalytical and Nuclear Chemistry | Year: 2017

In the light of the values recommended by the International Union of Pure and Applied Chemistry for the isotopic composition of the elements, the feasibility of using low abundant isotopes to determine some elements by reactor neutron activation analysis is discussed. The characteristics of the tables informing the pertinent data are described. In particular, the possibilities of determining sulphur, calcium, iron, nickel, selenium, strontium, tin, barium, gadolinium, ytterbium, mercury and uranium are revised. Some reflections on the situation of the analyst, as user of the literature data, are formulated. © 2017 Akadémiai Kiadó, Budapest, Hungary

Reisin E.R.,University of Buenos Aires | Scheer J.,University of Buenos Aires
Journal of Atmospheric and Solar-Terrestrial Physics | Year: 2017

We find that mesopause region temperatures determined by the SABER instrument on the TIMED satellite during nocturnal overpasses at El Leoncito (31.8°S, 69.3°W) are several kelvins higher when SABER observes from the East than when it observes from the West. We distinguish between altitudes corresponding to the nominal emission heights of the OH and O2 airglow layers. The East-West temperature differences of 4.5 K obtained for OH-equivalent height, and of 3.5 K for O2-equivalent height are surprising, because an effect of the South Atlantic Anomaly on SABER temperature is unexpected. However, the ground-based data obtained with our airglow spectrometer at El Leoncito show that such a SABER artifact can be ruled out. Rather, the phenomenon is explained as a consequence of the temporal sampling of the nocturnal variation, which is mostly due to the semidiurnal tide. The monthly mean tide is strongest from April to September with a mean amplitude of 6.9 K for OH, and of 10.5 K for O2 rotational temperature, but the contribution to the East-West effect varies strongly from month to month because of differences in the temporal sampling. This mechanism should be active at other sites, as well. © 2017 Elsevier Ltd

Kietzmann D.A.,University of Buenos Aires
Journal of South American Earth Sciences | Year: 2017

As part of microfacies studies carried out on the Tithonian – Valanginian carbonate ramp of the Neuquén Basin, two stratigraphic sections of the Vaca Muerta Formation (Arroyo Loncoche and Río Seco de la Cara Cura) were chosen in order to analyze the chitinoidellid content and distribution. Calpionellids in the studied sections are relatively poorly preserved; hyaline calcite walls are often recrystallized making the systematic determination difficult. However, microgranular calcite walls seem to have resisted better the incipient neomorphism presented by the limestones of the Vaca Muerta Formation. Seven known species of Chitinoidellidae and four known species of Calpionellidae are recognized. The distribution of calpionellid species allows recognizing the Chitinoidella and Crassicollaria Zones in the Neuquén Basin. The Chitinoidella Zone correlates with the Virgatosphinctes mendozanus–Windhauseniceras internispinosum Andean ammonite Zones, and can be divided into two subzones. The lower one is poorly defined, while the upper one can be assigned to the Boneti Subzone. The Crassicollaria Zone in the Neuquén basin needs a detailed revision, but data provided in this work enable its correlation at least with the Corongoceras alternans ammonite Zone. Similar associations were reported in Mexico and Cuba, showing good consistency between these regions. However, in the Neuquén Basin unlike the Tethys, chitinoidellids persist until the lower Berriasian. © 2017 Elsevier Ltd

Rouzaut S.,National University of Cordoba | Orgeira M.J.,University of Buenos Aires
Studia Geophysica et Geodaetica | Year: 2017

This contribution comprises geological and magnetic results obtained in loess and paleosols profiles outcropped in the Pampean plain (Argentina). The sedimentary sequence exposed in Córdoba province is represented by four profiles Corralito I, Corralito II, Monte Ral815o and Lozada, 32°S 64°14'W (Argentina). These profiles were mineralogically described and magnetically analyzed. The sediments that compound the profiles contain volcanic glass between 20 and 90%. The results of two paleosols with different percentage of volcanic glass in the parent material (correlated to Marine Isotope Stage 5, MIS 5) exposed at Corralito I and Lozada, were compared; an important relationship between environmental magnetism signal and volcanic glass content was observed. All the results suggest that there are variations between different paleosols of the same area and age; such variations are attributed to content of volcanic glass in parent material; time of exposure of the parent material to pedogenic processes; and geomorphological place of each profile. At present, it is not possible to quantify certainly the paleo-precipitation index. Only qualitative interpretation can be done taking into account many variables of the geological system. © 2017 Institute of Geophysics of the ASCR, v.v.i

Cavagnaro F.P.,University of Buenos Aires | Golluscio R.A.,University of Buenos Aires
Journal of Arid Environments | Year: 2017

This work focuses on the structural defenses of the two dominant spiny shrub species of the Patagonian shrub-grass steppe. We compared the amount of structural defenses (spines and thorns) of Mulinum spinosum (Cav.) Pers. (Apiaceae) and Adesmia volckmannii Phil. (Fabaceae) between grazed and long term non-grazed plots. M. spinosum showed a higher spinescence than A. volckmannii. Moreover, both species plants located in grazed plots showed higher spinescence than those located in non-grazed ones. Therefore, we can conclude that (1) M. spinosum has higher spinescence than A. volckmannii, probably because sheep prefer M. spinosum flowers than A. volckmannii leaves; and (2) both M. spinosum and A. volckmannii showed an increase of spinescence induced by herbivory. These responses may be evidences of co-evolution between these shrub species and large wild browsers that guarantee an adequate capacity to tolerate herbivory disturbance. Such capacity would be important to maintain community functioning, because shrubs provide secure sites for seed germination and, in some cases, are able to set symbiotic interactions with N-fixing bacteria. © 2017 Elsevier Ltd.

Plant populations are seriously threatened by anthropogenic habitat disturbance. In particular, defaunation may disrupt plant-disperser mutualisms, thus reducing levels of seed-mediated gene flow and genetic variation in animal-dispersed plants. This may ultimately limit their adaptive potential and ability to cope with environmental change. Tropical forest remnants are typically deprived of medium to large vertebrates upon which many large-seeded plants rely for accomplishing effective seed dispersal. Our main goal was to examine the potential early genetic consequences of the loss of large vertebrates for large-seeded vertebrate-dispersed plants. We compared the genetic variation in early-stage individuals of the large-seeded palm Syagrus romanzoffiana between continuous protected forest and nearby partially defaunated fragments in the Atlantic Forest of South America. Using nine microsatellites, we found lower allelic richness and stronger fine-scale spatial genetic structure in the disturbed area. In addition, the percentage of dispersed recruits around conspecific adults was lower, although not significantly, in the disturbed area (median values: 0.0 vs 14.4%). On the other hand, no evidence of increased inbreeding or reduced pollen-mediated gene flow (selfing rate and diversity of pollen donors) was found in the disturbed area. Our findings are strongly suggestive of some early genetic consequences resulting from the limitation in contemporary gene flow via seeds, but not pollen, in defaunated areas. Plant-disperser mutualisms involving medium–large frugivores, which are seriously threatened in tropical systems, should therefore be protected to warrant the maintenance of seed-mediated gene flow and genetic diversity in large-seeded plants.Heredity advance online publication, 25 January 2017; doi:10.1038/hdy.2016.130. © 2017 The Genetics Society Macmillan Publishers Limited, part of Springer Nature.

Vennari V.V.,CONICET | Aguirre-Urreta B.,University of Buenos Aires
Ameghiniana | Year: 2017

The earliest records of the genus Spiticeras Uhlig in Western Gondwana occur in the Upper Jurassic-Lower Cretaceous deposits of the Vaca Muerta Formation in the Neuquén Basin, Argentina. Those records involve two species, Spiticeras acutum Gerth and Spiticeras hauthali Gerth, which were firstly described from Arroyo Durazno, Mendoza. A systematic revision and reconsideration of the biostratigraphic distribution of both species was performed based on the study of type material and new bed-by-bed collections in the type locality and other southern Mendoza sections. S. acutum and S. hauthali display a succession of ornamentation stages that, together with other morphological characters, sustain their assignation to the genus Spiticeras. Addidionally, macroconchiate and microconchiate specimens were identified in both taxa. The record of S. acutum from the lowermost beds assigned to the Late Tithonian-Early Berrisian Substeueroceras koeneni Assemblage Biozone substantiates the downwards extension of the known range of the species in the Neuquén Basin. Given that the basal portion of the S. koeneni Biozone can be correlated with the Late Tithonian Standard "Durangites" Zone and that these early spiticeratins records have been found to be associated with a Late Tithonian secondary nannofossil bioevent (Raghodiscus asper (Stradner) first occurrence) in two of the studied sections, a Late Tithonian age is suggested for the earliest records of Spiticeras in Gondwana.

Deshayes A.,University of Buenos Aires | Rolla L.T.,NYU ECNU Institute of Mathematical science at NYU Shanghai
Stochastic Processes and their Applications | Year: 2016

In this paper we study the subcritical contact process on Zd for large times, starting with all sites infected. The configuration is described in terms of the macroscopic locations of infected regions in space and the relative positions of infected sites in each such region. © 2016.

Scientists have discovered the world's first fluorescent frog by accident while studying the pigment of polka-dot tree frogs found in the forests of Amazon basin. The South American polka dotted tree frog (Hypsiboas punctatus) appears to have dull browny-green skin dotted with red spots under normal light but herpetologist Carlos Taboada, from the University of Buenos Aires in Argentina, and colleagues found that it gives off a greenish-blue glow under ultraviolet light and in dim settings. Unlike in bioluminescent creatures whose light is produced by chemical reactions in their bodies, no chemical reaction occurs in biofluorescent organisms. Instead of giving off light from their own power source, these organisms typically absorb light at short wavelengths, transform it and then re-emit this at longer wavelengths as a different color. Biofluorescent light in animals can be produced and only becomes visible to humans when the fluorescent organism gets illuminated by external sources such as a UV light bulb. Fluorescence is more common in marine creatures such as sharks, fish, corals and is also found in the hawksbill turtle but it is rare in land animals having only previously known in parrots and in some scorpions. Prior to the discovery, biofluorescence in frogs is unheard of. The South American tree frog that Taboada and colleagues studied is the first amphibian discovered to fluoresce. It is not clear why some organisms have the special ability to glow in ultraviolet light albeit scientists have theories which include mate attraction, camouflage, and communication. For the South American fluorescent frogs, researchers suspect their fluorescence is relevant to visual perception. The amphibian's fluorescent molecules give off about 18 percent as much visible light as a full moon which is enough for related frog species to see by. Researchers want to conduct a further study of the photoreceptors found in the frog's eyes to determine if the amphibians use their fluorescence for better vision at night. "In low-light conditions, fluorescence accounts for an important fraction of the total emerging light, largely enhancing brightness of the individuals and matching the sensitivity of night vision in amphibians," the researchers wrote in their study published in journal PNAS. "These results introduce an unprecedented source of pigmentation in amphibians and highlight the potential relevance of fluorescence in visual perception in terrestrial environments." Fluorescence in marine organisms serves different purposes. Fluorescent pigment in shallow water corals acts as sunblock for the organisms as the intense ray of the sun that can cause sunburn to swimmers causes similar damage to corals and the symbiotic algae that live inside them. Scientists also found fluorescence in deep-sea corals. They think that fluorescent pigments in corals that live in deeper waters help produce more light for their symbiotic algae that need it for photosynthesis. A newly-found fluorescent species of polyps in the Red Sea is suspected of using its glow around its mouth to attract prey. The fluorescent flashlights can be seen by other invertebrates at sunset, sunrise and in the moonlight. © 2017 Tech Times, All rights reserved. Do not reproduce without permission.

NEW YORK--(BUSINESS WIRE)--White Ops, the leading provider of human verification technology, and Accenture Interactive, the digital agency of the global professional services firm, today announced the results of a new joint research report on behalf of the Union of Belgian Advertisers (UBA). Using White Ops technology, the “2017 Sophisticated Invalid Traffic Assessment: The State of Ad Fraud in the Belgian Market,” evaluates the level of ad fraud facing Belgian advertisers based on 248 million ad impressions commissioned by UBA members, between January and February 2017. The study concluded that sophisticated invalid traffic (SIVT) – which represents fraudulent traffic from bots – accounted for 2 percent of all desktop traffic. This finding suggests that Belgian advertisers are little affected by this type of fraud, compared to other markets, such as the U.S., where fraudulent levels ranged from 3 to 37 percent, according to prior White Ops research. Although fraud rates remain low, some publishers, campaign types and traffic sources experienced high levels of fraudulent activity. “Ad fraud remains a major challenge that affects the entire digital ecosystem globally,” said Michael Tiffany, CEO of White Ops. “While it is reassuring to see the Belgian market experiencing relatively low levels of fraudulent traffic, we should not rejoice. This study should, on the contrary, give us an opportunity to end cybercriminals. To achieve this, advertisers, agencies, publishers and technology partners must work together to better detect and prevent ad fraud, optimize media investments and ensure a higher level of transparency.” Chris Van Roey, CEO of UBA, added: “Advertisers are worried today about their investments in online media. Their confidence in the sector is under severe strain: lack of brand safety, limitation of viewability, lack of reliable campaign measures, etc. Online ad fraud is also well placed in this agenda. Advertisers invest in digital ads that are ultimately not seen by anyone. At the international level, this fraud has reached extremely high levels. The UBA wanted for its members, and with them, to do its own study to assess the importance of this problem in Belgium. Within the UBA, a working group set up more than a year ago, carried out this study under the guidance of Karim Debbah, UBA Media Manager. Apparently, the results for our market reveal a limited level of fraud.” “Digital advertising fraud is growing year on year at the pace of digital media spend. While helping our clients optimize their digital marketing spends, it seemed paramount for us to run this survey in Belgium to assess the level of fraud affecting the marketing efficiency of our clients. UBA and White Ops were then natural partners to run this initiative and we’re happy today to share its results,” said Wim Decraene, Head of Accenture Interactive for Belgium and Luxembourg. Additional findings from the study indicate that more than 90 percent of desktop-focused advertising came from programmatic and direct campaigns. They also show an uneven distribution of visibility on the Belgian market, unlike other markets, such as the U.S., where botnet operators have developed more sophisticated methods, proving that not all bots are created equal. The findings also showed that 98 percent of traffic, and majority of fraud detected in UBA campaigns, was directed at desktop ads. This figure is consistent with data from the companies surveyed, indicating that advertisers spend more than half of their budget on desktop display and video advertising, and much less on mobile advertising. As mobile is a growing area of investment for all advertisers, it deserves additional monitoring. For more information, download the complete study here. White Ops is the global leader in human verification technology and data integrity. In 2016, White Ops was the first company to receive Media Rating Council (MRC) accreditation for Sophisticated Invalid Traffic (SIVT) detection, paving the way for the industry and offering a full suite solution that includes viewability, brand safety, fraud detection and pre-bid verification. Working with some of the best hackers and ad tech specialists in the world, we’re able to think outside the box and create the best solutions for our clients. To learn more, visit whiteops.com and follow us on Twitter, LinkedIn and Facebook. Accenture is a leading global professional services company, providing a broad range of services and solutions in strategy, consulting, digital, technology and operations. Combining unmatched experience and specialized skills across more than 40 industries and all business functions – underpinned by the world’s largest delivery network – Accenture works at the intersection of business and technology to help clients improve their performance and create sustainable value for their stakeholders. With approximately 401,000 people serving clients in more than 120 countries, Accenture drives innovation to improve the way the world works and lives. Visit us at www.accenture.com. Accenture Interactive helps the world’s leading brands transform their customer experiences across the entire customer journey. Through our connected offerings in design, marketing, content and commerce, we create new ways to win in today’s experience-led economy. Accenture Interactive was ranked the world’s largest and fastest-growing digital agency in the latest Ad Age Agency Report. To learn more follow us @accenturesocial and visit www.accenture.com/interactive. UBA is the Belgian organisation made by brands, made for brands. Today, the UBA member community consists of 300 companies who account for the majority of national media investments. As a result, UBA is a unique platform enabling its members to protect the interests of brands and engage in the exchange of knowledge. Through its extensive range of activities and services, UBA stimulates a creative, innovative and transparent communication ecosystem enabling strong and sustainable brands. In the development of its activities and services, UBA consistently implements four strategic principles: inspire, impact, enable and connect. These principles guarantee a relevant service that makes brand builders stronger.

Background: New oral anticoagulant (NOAC) drugs are known to influence the results of some routine hemostasis tests. Further data are needed to enable routine assessment of the effects of NOAC on clotting parameters in some special circumstances. Methods: Following administration of rivaroxaban to patients, at the likely peak and trough activity times, we assessed the effects on prothrombin time (PT), activated partial thromboplastin time (APTT), thrombin time (TT), and clotting time using Russell's viper venom, and in the presence of phospholipids and calcium reagent available as DVVreagent® and DVVconfirm®. The data were used to determine an adequate NOAC plasma level based on anticoagulant activities expressed as a ratio (patients/normal, R-C). Results: DVVconfirm as R-C could be rapidly performed, and the results were reasonably sensitive for rivaroxaban and probably for other FX inhibitors. This assay is not influenced by lupus anticoagulant and heparin, does not require purified NOAC as control, and will measure whole-plasma clotting activity. Conclusions: We propose a cut-off R-C value of 4.52 ± 0.33 for safety, but clinical studies are needed to establish whether this cut-off is useful for identifying patients at increased risk of hemorrhage or exhibiting low anticoagulation effect. It also seems possible that normal R-C could indicate an absence of anticoagulant activity when rivaroxaban is discontinued due to episodes of uncontrolled bleeding during anticoagulation or for emergency surgery. © 2014 Altman and Gonzalez; licensee BioMed Central Ltd.

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.

Galleano M.,University of Buenos Aires | Pechanova O.,Slovak Academy of Sciences | Fraga C.G.,University of Buenos Aires | Fraga C.G.,University of California at Davis
Current Pharmaceutical Biotechnology | Year: 2010

Fruits and vegetables are key foods whose high ingestion is associated with the improvement of numerous pathological conditions, including hypertension. Such health promoting actions have been increasingly ascribed to the antioxidant characteristics of different polyphenols in fruits and vegetables. Consequently, based on this assumption, many beverages and foods rich in polyphenols, grape, tea, cocoa, and soy products and many of their chemical constituents purified, are being studied both, as antioxidants and antihypertensive agents. This paper reviews the current evidence linking high polyphenol consumption with reductions in blood pressure. Basic chemical aspects of flavanols, flavonols, isoflavones and stilbenes, as possible responsible for the observed effects of those foods on blood pressure are included. Human intervention studies by using grapes and wine, cocoa and chocolate, black and green tea, soy products, and purified compounds ((+)-catequin, quercetin, (-)-epigallocatechin gallate) are summarized. The discussed hypothesis, strongly supported by experimental data in animals, is that by regulating nitric oxide bioavailability, polyphenols present in fruits and vegetables affect endothelial function and as a consequence, blood pressure. Even when data are not definitive and many questions remain open, the whole evidence is encouraging to start considering diets that can provide benefits to hypertensive subjects, and those benefits will be more significant in people that do not have controlled his/her elevated blood pressure. © 2010 Bentham Science Publishers Ltd.

Maurel C.,Montpellier University | Simonneau T.,French National Institute for Agricultural Research | Sutka M.,Montpellier University | Sutka M.,University of Buenos Aires
Journal of Experimental Botany | Year: 2010

Roots are the primary sites of water uptake by plants. Roots also sense most of the physico-chemical parameters of the soil, perceive signals from the shoots, and adjust their growth and water transport properties accordingly. The present opinion paper discusses the significance of the variable water transport capacity (hydraulic conductance) of roots during development and in response to environmental stimuli. It is shown that root hydraulics determines water uptake intensities but also water potential gradients within the plant. It is indicated how the dynamics of root hydraulics contributes to many integrated plant nutritional and growth functions. For instance, the heterogeneity of soil water and nutrient availability and the heterogeneity of root hydraulic properties feed each other and play critical roles in root transport functions. Another important aspect is the integration of root hydraulics within the mutual interactions of roots and shoots, for co-ordinated growth and water-saving responses to drought. © 2010 The Author(s).

Medina F.,University of Seville | Mesa F.,University of Seville | Skigin D.C.,University of Buenos Aires | Skigin D.C.,CONICET
IEEE Transactions on Microwave Theory and Techniques | Year: 2010

Extraordinary transmission and other interesting related phenomena for 1-D periodic arrays of slits (compound diffraction gratings) have recently been the object of intense research in the optics and solid state physics communities. This case should be differentiated from the extraordinary transmission through arrays of small apertures on metal screens since small holes only support below-cutoff modes, whereas slits can also support transverse electromagnetic modes without cutoff frequency. In this paper, an equivalent-circuit approach is proposed to account for the most relevant details of the behavior of slit-based periodic structures: extraordinary transmission peaks, FabryProt resonances, and transmission dips observed in compound structures. The proposed equivalent-circuit model, based on well-established concepts of waveguide and circuit theory, provides a simple and accurate description of the phenomenon that is appropriate for educational purposes, as well as for the design of potential devices based on the behavior of the structures under study. © 2006 IEEE.

Quinteros J.,German Research Center for Geosciences | Quinteros J.,University of Buenos Aires | Sobolev S.V.,German Research Center for Geosciences | Sobolev S.V.,Russian Academy of Sciences
Geology | Year: 2013

The classic example of the not-well-understood rapid change of tectonic plate motion is the increase and then decrease of the convergence rate between the Nazca and South America plates during the past 25-20 m.y. that coincided with the growth of the Andes Mountains. Currently, the decrease in convergence rate is explained either by the increasing load of the Andes or by the appearance of fl at slab segments beneath South America. Here, we present an alternative view based on a thermomechanical self-consistent (gravity driven) model of Nazca plate subduction. We explain the changes in the convergence rate as a natural consequence of the Nazca plate penetration into the transition zone and lower mantle after long-term oblique subduction of the Farallon plate. The model is consistent with seismic tomographic images of the Nazca plate beneath South America. Our model also shows that the presence of the Andes does not signifi cantly affect the convergence rate between the Nazca and South America plates. © 2012 Geological Society of America.

The Screaming Cowbird (Molothrus rufoaxillaris) is the most specialized brood-parasitic cowbird, relying almost entirely on the Bay-winged Cowbird (Agelaioides badius) as host. Recently, Screaming Cowbirds have expanded their range to areas where Bay-winged Cowbirds are absent, and they are exploiting the Chopi Blackbird (Gnorimopsar chopi). Interactions between Screaming Cowbirds and Chopi Blackbirds are largely unexplored, as is the reproductive success of the parasite in this host. Screaming Cowbirds, Chopi Blackbirds, and Bay-winged Cowbirds coexist in northeastern Argentina, providing an ideal system to explore interactions between a specialist brood parasite and an alternative host and to compare the reproductive success of the parasite in its main host and in an alternative host. Screaming Cowbirds parasitized both hosts throughout their breeding seasons (Chopi Blackbirds, mid-October to mid-January; Bay-winged Cowbirds, mid-November to mid-March). Frequency of parasitism was lower in Chopi Blackbirds than in Bay-winged Cowbirds (46% vs. 74%). Nest survival was higher in Chopi Blackbirds than in Bay-winged Cowbirds (37% vs. 15%). In successful nests, survival of Screaming Cowbird eggs and chicks was high and relatively similar in both hosts (Chopi Blackbirds: eggs, 99%; chicks, 90%; Bay-winged Cowbirds: eggs, 93%; chicks, 93%), but hatchability was lower in Chopi Blackbirds than in Bay-winged Cowbirds (52% vs. 92%). Considering (1) nest survival and (2) egg survival, hatchability, and chick survival in successful nests, the reproductive success of Screaming Cowbirds (i.e. proportion of eggs that resulted in fledglings) was 0.17 in Chopi Blackbirds and 0.12 in Bay-winged Cowbirds. Our results indicate that the Chopi Blackbird is a frequent host of the Screaming Cowbird, and parasitism of this alternative host may help explain the range expansion of this parasite in areas of Brazil where the Bay-winged Cowbird is absent. © 2015 American Ornithologists' Union.

De La Matta M.,University of Buenos Aires | De La Matta M.,Friedrich Miescher Institute for Biomedical Research | Lafaille C.,University of Buenos Aires | Kornblihtt A.R.,University of Buenos Aires
RNA | Year: 2010

Alternative splicing accounts for much of the complexity in higher eukaryotes. Thus, its regulation must allow for flexibility without hampering either its specificity or its fidelity. The mechanisms involved in alternative splicing regulation, especially those acting through coupling with transcription, have not been deeply studied in in vivo models. Much of our knowledge comes from in vitro approaches, where conditions can be precisely controlled at the expense of losing several levels of regulation present in intact cells. Here we studied the relative order of removal of the introns flanking a model alternative cassette exon. We show that there is a preferential removal of the intron downstream from the cassette exon before the upstream intron has been removed. Most importantly, both cis-acting mutations and trans-acting factors that regulate the model alternative splicing event differentially affect the relative order of removal. However, reduction of transcriptional elongation causing higher inclusion of the cassette exon does not change the order of intron removal, suggesting that the assumption, according to the "first come, first served" model, that slow elongation promotes preferential excision of the upstream intron has to be revised. We propose instead that slow elongation favors commitment to exon inclusion during spliceosome assembly. Our results reveal that measuring the order of intron removal may be a straightforward read-out to discriminate among different mechanisms of alternative splice site selection.

Niederman M.S.,Winthrop University | Niederman M.S.,State University of New York at Stony Brook | Luna C.M.,Hospital Of Clinicas | Luna C.M.,University of Buenos Aires
Seminars in Respiratory and Critical Care Medicine | Year: 2012

Community-acquired pneumonia (CAP) is a common cause of morbidity and mortality worldwide, and since 1993, guidelines for management have been available. The process, which first began in the United States and Canada, has now been implemented in numerous countries throughout the world, and often each geographic region or country develops locally specific recommendations. It is interesting to realize that guidelines from different regions often interpret the same evidence base differently, and guidelines differ from one country to another, even though the bacteriology of CAP is often more similar than different from one region to another. One of the unique contributions of the 2007 US guidelines is the inclusion of quality and performance measures. In addition, US guidelines emphasize management principles that differ from some of the principles in European guidelines because of unique epidemiological considerations. In addition, certain therapy principles apply in the United States that differ from those in other regions, including the need for all patients to receive routine therapy for atypical pathogens, the emergence of community-acquired methicillin-resistant Staphylococcus aureus in some patients following influenza, and the need for all patients admitted to the intensive care unit to receive at least two antimicrobial agents. In the future, as guidelines evolve, there will be an important place for regional guidelines, particularly if these guidelines can recommend locally specific strategies to implement guidelines, which if successful, can lead to improved patient outcomes. Copyright © 2012 by Thieme Medical Publishers, Inc.

Tytiun A.E.,University of Buenos Aires | Argento C.J.,University of Buenos Aires
Journal of Refractive Surgery | Year: 2010

PURPOSE: To evaluate the short- and long-term sequential histological changes of the cornea in vivo after corneal collagen cross-linking (CXL) in patients with keratoconus. METHODS: Eighteen patients with keratoconus (Amsler-Krumeich classification: stages I, II, and III) underwent CXL with riboflavin/ultraviolet A (UVA) in one eye. The corneas were examined preoperatively and within 5 hours, 7 and 14 days, and 1, 3, 6, 9, 12, 18, 24, and 36 months after the procedure using in vivo confocal microscopy. RESULTS: Early changes included edema, superficial nerve loss, cellular modifications, and isolated endothelial damage. At intermediate time points, there was nerve fiber regeneration, increased reflectivity of the extracellular matrix, enlarged keratocytes and extracellular deposits, and remodeling of the endothelial layer (two eyes). At later time points, loss of keratocytes and remodeling of the extracellular deposits were noted. CONCLUSIONS: Although the cornea has no significant tissue modifications clinically after CXL, this study has shown that corneal wounding by riboflavin/UVA collagen CXL induces cellular wound-healing mechanisms and alters the normal structure and cellularity of the cornea for up to 36 months. Copyright © SLACK Incorporated.

Verstraeten S.V.,CONICET | Fraga C.G.,University of Buenos Aires | Oteiza P.I.,University of California at Davis
Food and Function | Year: 2015

Flavonoids are a type of phenolic compound widely present in edible plants. A great number of health benefits have been ascribed to flavonoid consumption in the human population. However, the molecular mechanisms involved in such effects remain to be identified. The flavan-3-ols (-)-epicatechin and (+)-catechin, and their related oligomers (procyanidins) have been thoroughly studied because of their capacity to interact with cell membranes. Starting with these interactions, procyanidins could modulate multiple biochemical processes, such as enzyme activities, receptor-ligand binding, membrane-initiated cell signaling, and molecule transport across membranes. This review focuses on molecular aspects of procyanidin interactions with membrane lipid components, and the resulting protection of the membranes against mechanical and/or oxidative damage, resulting in the maintenance of cell functions. This journal is © The Royal Society of Chemistry.

Mac Keon S.,CONICET | Gazzaniga S.,University of Buenos Aires | Wainstok R.,CONICET | Wainstok R.,University of Buenos Aires
Frontiers in Immunology | Year: 2015

Dendritic cells (DCs) play a pivotal role in the orchestration of immune responses, and are thus key targets in cancer vaccine design. Since the 2010 FDA approval of the first cancer DC-based vaccine (Sipuleucel-T), there has been a surge of interest in exploiting these cells as a therapeutic option for the treatment of tumors of diverse origin. In spite of the encouraging results obtained in the clinic, many elements of DC-based vaccination strategies need to be optimized. In this context, the use of experimental cancer models can help direct efforts toward an effective vaccine design. This paper reviews recent findings in murine models regarding the antitumoral mechanisms of DC-based vaccination, covering issues related to antigen sources, the use of adjuvants and maturing agents, and the role of DC subsets and their interaction in the initiation of antitumoral immune responses. The summary of such diverse aspects will highlight advantages and drawbacks in the use of murine models, and contribute to the design of successful DC-based translational approaches for cancer treatment. © 2015 Mac Keon, Ruiz, Gazzaniga and Wainstok.

Giribet G.,University of Buenos Aires | Giribet G.,Pontifical Catholic University of Valparaíso | Goya A.,University of Buenos Aires | Oliva J.,Austral University of Chile
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2015

We investigate the thermodynamics of hairy black holes in asymptotically anti-de Sitter (AdS) space, including backreaction. Resorting to the Euclidean path integral approach, we show that matter conformally coupled to Einstein gravity in five dimensions may exhibit a phase transition whose endpoint turns out to be a hairy black hole in AdS5 space. The scalar field configuration happens to be regular everywhere outside and on the horizon and behaves asymptotically in such a way that respects the AdS boundary conditions that are relevant for AdS/CFT. The theory presents other peculiar features in the ultraviolet, like the existence of black holes with arbitrarily low temperature in AdS5. This provides a simple setup in which the fully backreacting problem of a hair forming in AdS at a certain critical temperature can be solved analytically. © 2015 American Physical Society.

Fraga C.G.,University of Buenos Aires | Fraga C.G.,University of California at Davis | Oteiza P.I.,University of California at Davis
Free Radical Biology and Medicine | Year: 2011

Plant polyphenols are among the most abundant phytochemicals present in human diets. Increasing evidence supports the health-promoting effects of certain polyphenols, including flavonoids. This review discusses current knowledge of the capacity of monomeric flavanols, i.e., (-)-epicatechin and (+)-catechin, and their derived procyanidins to modulate cell signaling and the associations of these actions with better health. Flavanols and procyanidins can regulate cell signaling through different mechanisms of action. Monomers and dimeric procyanidins can be transported inside cells and directly interact and modulate the activity of signaling proteins and/or prevent oxidation. Larger and nonabsorbable procyanidins can regulate cell signaling by interacting with cell membrane proteins and lipids, inducing changes in membrane biophysics, and by modulating oxidant production. All these actions would be limited by the bioavailability of flavanols at the target tissue. The protection from cardiac and vascular disease and from cancer that is associated with a high consumption of fruit and vegetables could be in part explained by the capacity of flavanols and related procyanidins to modulate proinflammatory and oncogenic signals. © 2011 Elsevier Inc. All rights reserved.

Limarino C.O.,University of Buenos Aires | Cesari S.N.,Museo Argentino de Ciencias Naturales Bernardino Rivadavia | Spalletti L.A.,CONICET | Taboada A.C.,CONICET | And 4 more authors.
Gondwana Research | Year: 2014

This paper provides a review of the Late Mississippian to Permian paleoclimatic history for southern South America based on lithologic indicators, biostratigraphic information, and chronostratigraphic data. The region is divided into three major types of basins: 1. Eastern intraplate basins (e.g., Paraná Basin), 2. Western retroarc basins (e.g., Paganzo Basin) and 3. Western arc-related basins (e.g., Río Blanco Basin). Four major types of paleoclimatic stages are recognized in these basins: 1. glacial (late Visean-early Bashkirian), 2. terminal glacial (Bashkirian-earliest Cisuralian) 3. postglacial (Cisuralian-early Guadalupian), and 4. semiarid-arid (late Guadalupian-Lopingian). The glacial stage began in the late Visean and continued until the latest Serpukhovian or early Bashkirian in almost all of the basins in southern South America. During the Bashkirian-earliest Cisuralian (terminal glacial stage), glacial deposits disappeared almost completely in the western retroarc basins (e.g., Paganzo Basin) but glaciation persisted in the eastern basins (e.g., Paraná and Sauce Grande Basins). A gradual climatic amelioration (postglacial stage) began to occur during the earliest Permian when glacial deposits completely disappeared across all of South America. During this interval, glacial diamictites were replaced by thick coal beds in the Paraná Basin while north-south climatic belts began to be delineated in the western basins, which were likely controlled by the distribution of mountain belts along the Panthalassan Margin of South America. Towards the late Permian, climatic belts became less evident and semiarid or arid conditions dominated in the southern South America basins. Eolian dunes, playa lake deposits, and mixed eolian-fluvial sequences occur in the Paraná Basin and in the western retroarc basins. Volcanism and volcaniclastic sedimentation dominated along the western margin of South America at that time. The stratigraphic record obtained in southern South America supports a long duration transition from icehouse to extreme greenhouse conditions. © 2013 International Association for Gondwana Research.

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.

Verstraeten S.V.,University of Buenos Aires | Mackenzie G.G.,University of California at Davis | Oteiza P.I.,University of California at Davis
Biochimica et Biophysica Acta - Biomembranes | Year: 2010

The mechanisms by which lymphocytes recognize and interpret mechanical stimuli and translate these into the triggering of select signaling cascades that are critical for lymphocyte function are still not fully understood. In this work, we investigated the association of mechanical stress (MS)-induced changes in membrane physical properties with changes in cytoskeleton dynamics and cell signaling. In Jurkat T cells, MS was associated with the immediate and transient depolymerization of both β-tubulin and F-actin. The fluidity of the plasma membrane measured in the hydrophobic region of the bilayer, increased 0.5min post-MS, recovering the initial value in the following 2min. This effect was accompanied by the rearrangement of lipids in the lateral phase of the plasma membrane, transient lipid rafts' alteration, and membrane hyperpolarization. The consequent increase in cellular [Ca2+] triggered the activation of the transcription factors NFAT, AP-1, and NF-κB. Results indicate that the cytoplasmic membrane, through changes in membrane physical properties, senses MS, and transduces an initial physical stimulus into microtubules rearrangements, Ca2+ mobilization, and the subsequent changes in cell signaling. © 2010 Elsevier B.V.

Abad-Franch F.,Instituto Leonidas e Maria Deane Fiocruz | Gurgel-Goncalves R.,University of Brasilia | Gurtler R.E.,University of Buenos Aires
Memorias do Instituto Oswaldo Cruz | Year: 2013

Certifying the absence of Chagas disease transmission by native vectors lacks scientific grounds and weakens long-term control-surveillance systems to the detriment of people living under risk conditions. Instead, a regular "certification of good practice" (including vector control-surveillance, case detection/patient care and blood safety) could help achieve sustained disease control.

Murer M.G.,University of Buenos Aires | Moratalla R.,Instituto Cajal | Moratalla R.,Institute Salud Carlos III
Frontiers in Neuroanatomy | Year: 2011

Parkinson's disease is a common neurodegenerative disorder caused by the degeneration of midbrain substantia nigra dopaminergic neurons that project to the striatum. Despite extensive investigation aimed at finding new therapeutic approaches, the dopamine precursor molecule, 3,4-dihydroxyphenyl-L-alanine (L-DOPA), remains the most effective and commonly used treatment. However, chronic treatment and disease progression lead to changes in the brain's response to L-DOPA, resulting in decreased therapeutic effect and the appearance of dyskinesias. L-DOPA-induced dyskinesia (LID) interferes significantly with normal motor activity and persists unless L-DOPA dosages are reduced to below therapeutic levels. Thus, controlling LID is one of the major challenges in Parkinson's disease therapy. LID is the result of intermittent stimulation of supersensitive D1 dopamine receptors located in the very severely denervated striatal neurons. Through increased coupling to Gα olf, resulting in greater stimulation of adenylyl-cyclase, D1 receptors phosphorylate DARPP-32, and other protein kinase A targets. Moreover, D1 receptor stimulation activates extracellular signal-regulated kinase and triggers a signaling pathway involving mammalian target for rapamycin and modifications of histones that results in changes in translation, chromatin modification, and gene transcription. In turn, sensitization of D1 receptor signaling causes a widespread increase in the metabolic response to D1 agonists and changes in the activity of basal ganglia neurons that correlate with the severity of LID. Importantly, different studies suggest that dyskinesias may share mechanisms with drug abuse and long term memory involving D1 receptor activation. Here we review evidence implicating D1 receptor signaling in the genesis of LID, analyze mechanisms that may translate enhanced D1 signaling into dyskinetic movements, and discuss the possibility that the mechanisms underlying LID are not unique to the Parkinson's disease brain. © 2011 Murer and Moratalla.

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.

Cesari S.N.,Museo Argentino de Cs. Naturales | Limarino C.O.,University of Buenos Aires | Gulbranson E.L.,University of California at Davis
Earth-Science Reviews | Year: 2011

The Carboniferous and Permian fossiliferous sequences of the central-western Argentina contain abundant plant remains, palynomorphs and invertebrates. They include a continuous record of large distribution in the Paganzo, Rio Blanco, Calingasta-Uspallata and San Rafael Basins. The most recent biostratigraphic schemes recognize a floristic succession represented by the biozones: Archaeosigillaria-Frenguellia (AF Biozone), Frenguellia eximia-Nothorhacopteris kellaybelenensis-Cordaicarpus cesarii (FNC Biozone), Nothorhacopteris-Botrychiopsis-Ginkgophyllum (NBG Biozone), Interval Biozone and Gangamopteris Biozone. The associated palynological record is represented by the biozones: Reticulatisporites magnidictyus-Verrucosisporites quasigobbetti (MQ Biozone), Raistrickia densa-Convolutispora muriornata (DM Biozone), Pakhapites fusus-Vittatina subsaccata (FS Biozone), and Lueckisporites-Weylandites (LW Biozone). The precise age of the Upper Paleozoic western Gondwanan biozones has been under discussion and remains controversial to date in some regions. The main issue hampering an integrated comparison of the Gondwanan biozones was its imprecise chronostratigraphic framework. However, new studies in some Argentinian stratigraphic sections bearing floras and faunas have yielded several radiometric ages. From these 206Pb/238U zircon datings it is possible to determine the chronostratigraphic range of many fossiliferous assemblages in this sector of Gondwana. In this way, the AF and MQ Biozones are restricted to the Late Mississippian and they would be not younger than 335Ma according to radiometric ages. 206Pb/238U ages suggest that the NBG, DMa and DMb Biozones characterize the Late Serpukhovian glacial deposits and persisted up to the Late Bashkirian. Beds containing the Interval and DMc Biozones have yielded 206Pb/238U ages of 312.82±0.11Ma and 310.71±0.1Ma which would indicate that both zones characterize the Moscovian. The remains of Gangamopteris Biozone found in the Paganzo Basin overlie basalt levels ranging between 308±6 and 293±6Ma. Therefore, the incoming of the first glossopterids was closely associated to the Carboniferous-Permian boundary in this part of Gondwana. The data presented in this paper are used for establishing comparisons with other Gondwanan biozones, constrained by absolute ages. © 2011 Elsevier B.V.

Adamo A.M.,University of Buenos Aires | Oteiza P.I.,University of California at Davis
BioFactors | Year: 2010

Zinc is essential for normal brain development. Gestational severe zinc deficiency can lead to overt fetal brain malformations. Although not teratogenic, suboptimal zinc nutrition during gestation can have long-term effects on the offspring's nervous system. This article will review current knowledge on the role of zinc in modulating neurogenesis and neuronal apoptosis as well as the proposed underlying mechanisms. A decrease in neuronal zinc causes cell cycle arrest, which in part involves a deregulation of select signals (ERK1/2, p53, and NF-κB). Zinc deficiency also induces apoptotic neuronal death through the intrinsic (mitochondrial) pathway, which can be triggered by the activation of the zincregulated enzyme caspase-3, and as a consequence of abnormal regulation of prosurvival signals (ERK1/2 and NF-κB). Alterations in the finely tuned processes of neurogenesis, neuronal migration, differentiation, and apoptosis, which involve the developmental shaping of the nervous system, could have a long-term impact on brain health. Zinc deficiency during gestation, even at the marginal levels observed in human populations, could increase the risk for behavioral/ neurological disorders in infancy, adolescence, and adulthood. © 2010 International Union of Biochemistry and Molecular Biology, Inc.

Fraga C.G.,University of Buenos Aires | Fraga C.G.,University of California at Davis | Galleano M.,University of Buenos Aires | Verstraeten S.V.,University of Buenos Aires | Oteiza P.I.,University of California at Davis
Molecular Aspects of Medicine | Year: 2010

Polyphenols and consequently many flavonoids have several beneficial actions on human health. However, the actual molecular interactions of polyphenols with biological systems remain mostly speculative. This review addresses the potential mechanisms of action that have been so far identified, as well as the feasibility that they could occur in vivo. Those mechanisms include: i) non specific actions, based on chemical features common to most polyphenols, e.g. the presence of a phenol group to scavenge free radicals; and ii) specific mechanisms; based on particular structural and conformational characteristics of select polyphenols and the biological target, e.g. proteins, or defined membrane domains. A better knowledge about the nature and biological consequences of polyphenol interactions with cell components will certainly contribute to develop nutritional and pharmacological strategies oriented to prevent the onset and/or the consequences of human disease. © 2010 Elsevier Ltd.

Camino N.A.,University of Buenos Aires | Sanchez C.C.,University of Seville | Rodriguez Patino J.M.,University of Seville | Pilosof A.M.R.,University of Buenos Aires
Food Hydrocolloids | Year: 2012

In this work we have studied the bulk, interfacial and emulsification behavior of a surface-active polysaccharide, hydroxypropylmethylcelulose (HPMC) and β-lactoglobulin (βlg) mixtures at two pHs, 3 and 6.The absence of an increase of particle size or a modification of zeta potential in HPMC/βlg mixtures indicated that both biopolymers would not form complexes in the bulk at pH 6. The protein presented a positive charge at pH 3, which makes possible the formation of a weak complex with the HPMC.The interface was dominated by the protein, indicating the displacement of the less surface-active HPMC at pH 6. The interfacial pressure of the HPMC/βlg mixture at pH 3 failed in between the curves corresponding to the single components βlg Complexation may decrease its availability to adsorb at the O/W interface, lowering the mixture interfacial pressure.A bimodal distribution was obtained in emulsions at pH 6 and their confocal images evidenced a strong flocculation, non-adsorbed HPMC would remain in the continuous phase, thus promoting depletion flocculation of oil droplets. At pH 3 the emulsion droplet size distribution curve was bimodal, indicating polidispersity. Nevertheless, a high stability to coalescence was observed. The mixed emulsion zeta potential is reduced in comparison with the protein alone, indicating complexation between βlg and HPMC. When analyzing the confocal microcopy images of recently prepared emulsions, no flocculation was observed. © 2011 Elsevier Ltd.

Finzi A.C.,Boston University | Austin A.T.,University of Buenos Aires | Cleland E.E.,University of California at San Diego | Frey S.D.,University of New Hampshire | And 2 more authors.
Frontiers in Ecology and the Environment | Year: 2011

The biogeochemical cycles of carbon (C), nitrogen (N), and phosphorus (P) are fundamental to life on Earth. Because organisms require these elements in strict proportions, the cycles of C, N, and P are coupled at molecular to global scales through their effects on the biochemical reactions controlling primary production, respiration, and decomposition. The coupling of the C, N, and P cycles constrains organismal responses to climatic and atmospheric change, suggesting that present-day estimates of climate warming through the year 2100 are conservative. N and P supplies constrain C uptake in the terrestrial biosphere, yet these constraints are often not incorporated into global-scale analyses of Earth's climate. The inclusion of coupled biogeochemical cycles is critical to the development of next-generation, global-scale climate models. © The Ecological Society of America.

Fraga C.G.,University of Buenos Aires | Fraga C.G.,University of California at Davis | Oteiza P.I.,University of California at Davis | Galleano M.,University of Buenos Aires
Biochimica et Biophysica Acta - General Subjects | Year: 2014

Background One of the strategies most commonly used to assess a free radical-antioxidant balance in chemical and biological systems is the determination of the total antioxidant capacity (TAC). A large amount of research has been published using TAC. However, it remains unclear which is the significance of these investigations for understanding the biological importance of free radical reactions. Scope of review This review discusses the relevance and limitations of TAC for the assessment of the antioxidant activities present in food and food derivatives, and in body tissues and fluids. Major conclusions TAC determinations are simple, inexpensive, and able to evaluate the capacity of known and unknown antioxidants and their additive, synergistic and/or antagonistic actions, in chemical and biological systems. However, different TAC assays correlate poorly with each other, since each TAC assay is sensitive to a particular combination of compounds, but exclude many others. The TAC values for foods cannot be translated to the in vivo (human) antioxidant defenses, and furthermore, to health effects provided by that food. General significance Up to date, conclusions that can be drawn from the extensive amount of research done using TAC of foods or populations should not be considered when used for making decisions affecting population health. This article is part of a Special Issue entitled Current methods to study reactive oxygen species - pros and cons and biophysics of membrane proteins. Guest Editor: Christine Winterbourn. © 2013 Elsevier B.V.

Agency: European Commission | Branch: FP7 | Program: CSA | Phase: INFRA-2007-1.2.3;INFRA-2007-1.2-03 | Award Amount: 5.11M | Year: 2008

EELA-2 aims to build, on the current EELA e-Infrastructure, a high capacity, production-quality, scalable Grid Facility providing round-the-clock, worldwide access to distributed computing, storage and network resources for a wide spectrum of applications from European and Latin American scientific communities. The project will provide an empowered Grid Facility with versatile services fulfilling application requirements and ensure the long-term sustainability of the e-Infrastructure beyond the term of the project. The specific EELA-2 objectives are: - Build a Grid Facility by: Expanding the current EELA e-Infrastructure to consist of more production sites mobilising more computing nodes and more storage space, at start of the project and to further grow storage over the duration of the project; Providing, in collaboration with related projects (e.g. EGEE), the full set of Grid Services needed by all types of scientific applications; Supporting applications various types (from classical off-line data processing up to control and data acquisition of scientific instruments), selected against well defined criteria (including grid added value, suitability for Grid deployment, outreach/potential impact); - Ensure the Grid Facility sustainability: Through the already established and new contacts with policy/decision makers, collaborating with RedCLARA and NRENs and supporting the ongoing creation of e-Science Initiatives and/or National Grid initiatives (NGI). Building the support of the e-Infrastructure to provide a complete set of Global Services from a Central Operation Centre and to pave the way for the creation of Regional Operation Centres in Latin America: Attracting new applications; Making available knowledge of EELA-2 Grid Facility to all potential users, developers, and decision makers through an extensive Training and Dissemination program; Creating knowledge repositories federated with the EGEE ones.

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: H2020 | Program: RIA | Phase: INT-12-2015 | Award Amount: 2.60M | Year: 2016

EULAC Focus addresses the whole set of topics included in the Call. It delivers a significant contribution to the improvement of EUCELAC relations through a better understanding of the three dimensions selected by the call: cultural, scientific and social. The main objective is that of giving focus to these three dimensions of EUCELAC relations, with a view to determining synergies and cross-fertilization, as well as identifying asymmetries in bi-lateral and bi-regional relations. Research is focused on areas crucial to explain the current state of relations between EU and LAC, and will be pursued at two levels: a) research activities; b) strategic set of recommendations. In order to guarantee high impact, the research is pursued in six interdisciplinary WPs, organized matricially. Three are horizontal : Cross-cutting pathways, Towards a common vision for EUCELAC and Dissemination and outreach. The other three are thematic/vertical: Cultural, Scientific and Social Dimension, and not only intersect the horizontal WPs but also interact between them. To achieve the objectives, the project is organized by the multidisciplinary and well balanced consortium of19 members from 15 counties. The consortium represents a unique group of highly competent and experienced institutions, composed specifically for the purpose of this project,comprising, in both regions, Gov Research Agencies, Research institutes, Universities, University Association, and two International European LA Organizations active in analytical and policy oriented research and dissemination. EULAC Focus builds upon the outcomes of prior mapping conducted at the bi-regional level and will facilitate access to end-users, as well as feeding into the work of the EU-LAC Foundation and informing bi-regional networking activities of the JIRI and T-APs work. The number of partners has been carefully defined to ensure project goals and proper diversity, while allowing for efficient project management.

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.

Agency: European Commission | Branch: FP7 | Program: CP-IP-SICA | Phase: KBBE-2009-2-4-02 | Award Amount: 7.82M | Year: 2010

Plant food supplements, or botanicals, have high acceptance by European consumers. Potentially, they can deliver significant health benefits, safely, and at relatively low costs. New regulations and EFSA guidance are also now in. However, concerns about safety, quality and efficacy of these products remain, and bottle-necks in risk and benefit assessments need to be solved. PlantLIBRA (PLANT food supplements: Levels of Intake, Benefit and Risk Assessment) aims to foster the safe use of food supplements containing plants or herbal extracts, by increasing science-based decision-making by regulators and food chain operators. To make informed decisions, competent authorities and food businesses need more quality-assured and accessible information and better tools (e.g., metadatabanks). PlantLIBRA is structured to develop, validate and disseminate data and methodologies for risk and benefit assessment and implement sustainable international cooperation. International cooperation, on-spot and in-language capacity building are necessary to ensure the quality of the plants imported in the EU. PlantLibra spans 4 continents and 23 partners, comprising leading academics, Small- and Medium-Sized Enterprises, industry and non-profit organizations. Through its partners it exploits the databases and methodologies of two Network of Excellences, EuroFIR and Moniqa. Plantlibra will also fill the gap in intake data by conducting harmonized field surveys in the regions of the EU and apply consumer sciences to botanicals. Existing composition and safety data will be collated into a meta-databank and new analytical data and methods will be generated. The overarching aim is to integrate diverse scientific expertise into a single science of botanicals. PlantLIBRA works closely with EFSA since several PlantLIBRA partners or experts are involved in the relevant EFSA Working Groups, and also plans shoulder-to-shoulder cooperation with competent authorities and stakeholders.

Agency: European Commission | Branch: FP7 | Program: CSA-SA | Phase: SST.2008.6.0.5. | Award Amount: 503.70K | Year: 2009

The primary aim of the proposed project ENABLE is to contribute to the external relations of EU with Latin American countries, specifically Argentina and Brazil, in the area of co-modal and intermodal freight transport. The project will stimulate sustainable freight transport systems with Latin American countries. In order to achieve this aim, the work plan of ENABLE entails inventories and surveys to obtain a sound picture of the situation of intermodal freight transport in Latin America; state-of-the-art reviews in Europe that will allow the identification of strengths and innovations of the European freight transport industry and research; and concrete roadmaps to facilitate their effective transfer to the target areas. Special attention will be paid to networking and partnership building actions that will strengthen the dialogue between Europe and Latin America, and foster international cooperation between the two geographical areas. A stakeholders Forum will be established in Latin America. Furthermore, Forum sessions, conferences and other dissemination actions will contribute to the visibility of the project results and engage the stakeholders of both sides in a fruitful dialogue. The partners of the project comprise a team that covers all disciplines that are essential and necessary for the successful implementation of the work plan. The two Latin American partners have a deep knowledge about the intermodal freight transport activities in their countries and the greater region, and they will play the role of agents in the knowledge transfer activities. The European partners are three of the most active organizations in the continents intermodal freight transport activities. The consortium will be assisted by the European Intermodal Association (EIA) by engaging its extensive know-how in European innovations, as well as its members expertise and contacts in the Latin American intermodal transport society.

Agency: European Commission | Branch: H2020 | Program: RIA | Phase: SFS-05-2015 | Award Amount: 5.67M | Year: 2016

The world demographic growth and global climate change are major challenges for human society,hence the need to design new strategies for maintaining high crop yield in unprecedented environmental conditions.The objective of TomGEM is to design new strategies aiming to maintain high yields of fruit and vegetables at harsh temperature conditions, using tomato as a reference fleshy fruit crop.As yield is a complex trait depending on successful completion of different steps of reproductive organ development, including flower differentiation and efficient flower fertilization,TomGEM will use trans-disciplinary approaches to investigate the impact of high temperature on these developmental processes.The core of the project deals with mining and phenotyping a vast range of genetic resources to identify cultivars/genotypes displaying yield stability and to uncover loci/genes controlling flower initiation,pollen fertility and fruit set.Moreover,since high yield and elevated temperatures can be detrimental to quality traits,TomGEM will also tackle the fruit quality issue.The goal is to provide new targets and novel strategies to foster breeding of new tomato cultivars with improved yield.The main strength of TomGEM resides in the use of unique and unexplored genetic resources available to members of the consortium.It gathers expert academic researchers and private actors committed to implement a multi-actor approach based on demand driven innovation.Tomato producers and breeders are strongly involved from design to implementation of the project and until the dissemination of results.TomGEM will provide new targets and novel strategies to foster the breeding of new tomato cultivars with improved yield under suboptimal temperature conditions.TomGEM will translate scientific insights into practical strategies for better handling of interactions between genotype,environment and management to offer holistic solutions to the challenge of increasing food quality and productivity.

Agency: European Commission | Branch: FP7 | Program: CP-SICA | Phase: ENERGY.2008.3.2.1 | Award Amount: 4.82M | Year: 2009

The increasing reliance on imported diesel fuels, in addition to annual increases in the quantities of organic wastes are threats to the EU and Latin America. This project (DIBANET) will combat these threats and help to eliminate diesel imports by developing novel technologies that will allow the sustainable production of diesel miscible biofuels from wastes. It will build on the key, complementary, strengths of researchers and industries of both regions to advance this field. This enhancement of co-operation will ensure that the whole process, from feedstock to process residues, is engineered for maximum efficiency. The links between regions will be further enhanced by the establishment of inter-regional student scholarships; 2 large brokerage events to engage all stakeholders; and a summer school for knowledge transfer. DIBANET will increase the yield from biomass, beyond the current art, of levulinic acid, a valuable platform chemical that can be combined with ethanol to make a diesel fuel. Processes will be advanced to utilise the solid residue that remains after the acid-treatment. From this residue treatment process a bio-oil and biochar will result. The bio-oil will be upgraded to produce a diesel miscible biofuel. The biochar will be examined for use as a soil amender for enhanced biomass yields. Advanced analytical techniques to benefit levulinic acid yields will be developed and employed online to allow real-time adjustment of biomass conversion conditions. All of the fuels produced will be tested to ensure compliance with current fuel requirements.

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.”

Heckman M.A.,University of Illinois at Urbana - Champaign | Weil J.,University of Buenos Aires | de Mejia E.G.,University of Illinois at Urbana - Champaign
Journal of Food Science | Year: 2010

Caffeine ranks as one of the top most commonly consumed dietary ingredients throughout the world. It is naturally found in coffee beans, cacao beans, kola nuts, guarana berries, and tea leaves including yerba mate. The total daily intake, as well as the major source of caffeine varies globally; however, coffee and tea are the 2 most prominent sources. Soft drinks are also a common source of caffeine as well as energy drinks, a category of functional beverages. Moderate caffeine consumption is considered safe and its use as a food ingredient has been approved, within certain limits, by numerous regulatory agencies around the world. Performance benefits attributed to caffeine include physical endurance, reduction of fatigue, and enhancing mental alertness and concentration. Caffeine has also been recently linked to weight loss and consequent reduction of the overall risks for developing the metabolic syndrome. However, the caloric contribution of caffeine-sweetened beverages needs to be considered in the overall energy balance. Despite all these benefits the potential negative effects of excessive caffeine intake should also be considered, particularly in children and pregnant women. © 2010 Institute of Food Technologists®.

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.

Alcoba D.R.,University of Buenos Aires | Torre A.,University of the Basque Country | Lain L.,University of the Basque Country | Bochicchio R.C.,University of Buenos Aires
Journal of Chemical Theory and Computation | Year: 2011

This work describes a Mulliken-type partitioning of the expectation value of the spin-squared operator <Ŝ 2> corresponding to an N-electron system. Our algorithms, which are based on a spin-free formulation, predict appropriate spins for the molecular fragments (at equilibrium geometries and at dissociation limits) and can be applied to any spin symmetry. Numerical determinations performed in selected closed- and open-shell systems at correlated level are reported. A comparison between these results and their counterpart ones arising from other alternative approaches is analyzed in detail. © 2011 American Chemical Society.

Ferraro R.,Institute Astronomia y Fisica Del Espacio | Ferraro R.,University of Buenos Aires
Journal of High Energy Physics | Year: 2010

The complex method to obtain 2-dimensional Born-Infeld electrostatic solutions is presented in a renewed form. The solutions are generated by a holomorphic seed that makes contact with the Coulombian complex potential. The procedure is exemplified by solving the Born-Infeld multipolar configurations. Besides, it is shown that the attractive force between two equal but opposite charges is lower than its Coulombian partner; it decreases up to vanish when the charges approach each other below a distance ruled by the Born-Infeld constant. © 2010 SISSA.

Ferraro R.,Institute Astronomia y Fisica del Espacio | Ferraro R.,University of Buenos Aires
General Relativity and Gravitation | Year: 2014

Newman-Janis algorithm for Kerr-Newman geometry is reanalyzed in the light of Cartan calculus. © 2014 Springer Science+Business Media New York.

Lazarowski A.,University of Buenos Aires | Lazarowski A.,Institute Biologia Celular Y Neurociencias Prof E Of Robertis | Czornyj L.,Hospital Of Pediatria Prof Dr Juan P Garrahan
Drug Metabolism and Drug Interactions | Year: 2011

Epilepsy is a common neurological disorder. About one-third of epilepsy patients have a multidrug resistance (MDR) phenotype and develop refractory epilepsy (RE). Changes in the properties of the antiepileptic drugs (AEDs) targets resulting in reduced drug sensitivity, can't explain the MDR phenotype. This particular refractoriness is now attributed to overexpression of multidrug transporters in brain, leading to impaired access of AEDs to CNS targets, and it was documented in both human as well as in experimental models of RE. Single nucleotide polymorphism (SNP) identified in the MDR1-ABCB1gene (C3435T/CC-genotype) is associated with increased intestinal expression of P-glycoprotein (P-gp) that affects levels of AEDs in plasma. The functional studies of P-gp using P-gp inhibitors could show the still unclear clinical impact of ABCB1 polymorphisms on AEDs resistance. Some drug-drug interactions previously believed to be cytochrome P450 (CYP) mediated are now also considered to be due to the modulation of multidrug-transporters. Because in certain cases pharmacoresistance can be overcome by add-on therapy, co-administered P-gp inhibitors could contribute to the effectiveness of AEDs treatment in RE. And in this regard, perhaps we can postulate to P-gp as a new clinical therapeutic target in multidrug-refractory epilepsy. © 2011 by Walter de Gruyter Berlin New York.

Valles A.S.,National University of the South | Barrantes F.J.,National University of the South | Barrantes F.J.,University of Buenos Aires
Biochimica et Biophysica Acta - Biomembranes | Year: 2012

The α7 subtype of nicotinic acetylcholine receptors (AChRs) is one of the most abundant members of the Cys-loop family of receptors present in the central nervous system. It participates in various physiological processes and has received much attention as a potential therapeutic target for a variety of pathologies. The importance of understanding the mechanisms controlling AChR assembly and cell-surface delivery lies in the fact that these two processes are key to determining the functional pool of receptors actively engaged in synaptic transmission. Here we review recent studies showing that RIC-3, a protein originally identified in the worm Caenorhabditis elegans, modulates the expression of α7 AChRs in a subtype-specific manner. Potentiation of AChR expression by post-transcriptional events is also critically assessed. © 2011 Elsevier B.V. All rights reserved.

Ferraro R.,Institute Astronomia y Fisica del Espacio | Ferraro R.,University of Buenos Aires | Fiorini F.,Institute Astronomia y Fisica del Espacio
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2010

In the context of Born-Infeld determinantal gravity formulated in an n-dimensional spacetime with absolute parallelism, we found an exact 3-dimensional vacuum circular symmetric solution without cosmological constant consisting in a rotating spacetime with non-singular behavior. The space behaves at infinity as the conical geometry typical of 3-dimensional General Relativity without cosmological constant. However, the solution has no conical singularity because the space ends at a minimal circle that no freely falling particle can ever reach in a finite proper time. The space is curved, but no divergences happen since the curvature invariants vanish at both asymptotic limits. Remarkably, this very mechanism also forbids the existence of closed timelike curves in such a spacetime. © 2010 Elsevier B.V.

Ferraro R.,Institute Astronomia y Fisica Del Espacio | Ferraro R.,University of Buenos Aires
Journal of Physics A: Mathematical and Theoretical | Year: 2010

In Born-Infeld theory and other nonlinear electrodynamics, the presence of a magnetostatic field modifies the dispersion relation and the energy velocity of waves propagating in a hollow waveguide. As a consequence, the transmitted power along a waveguide suffers slight changes when a magnetostatic field is switched on and off. This tiny effect could be better tested by operating the waveguide at a frequency close to the cutoff frequency. © 2010 IOP Publishing Ltd.

Cardinali D.P.,University of Buenos Aires | Srinivasan V.,Sri Sathya Sai Medical Educational and Research Foundation | Brzezinski A.,Hebrew University of Jerusalem | Brown G.M.,University of Toronto | Brown G.M.,Center for Addiction and Mental Health
Journal of Pineal Research | Year: 2012

Benzodiazepine sedative-hypnotic drugs are widely used for the treatment of insomnia. Nevertheless, their adverse effects, such as next-day hangover, dependence and impairment of memory, make them unsuitable for long-term treatment. Melatonin has been used for improving sleep in patients with insomnia mainly because it does not cause hangover or show any addictive potential. However, there is a lack of consistency on its therapeutic value (partly because of its short half-life and the small quantities of melatonin employed). Thus, attention has been focused either on the development of more potent melatonin analogs with prolonged effects or on the design of slow release melatonin preparations. The MT 1 and MT 2 melatonergic receptor ramelteon was effective in increasing total sleep time and sleep efficiency, as well as in reducing sleep latency, in insomnia patients. The melatonergic antidepressant agomelatine, displaying potent MT 1 and MT 2 melatonergic agonism and relatively weak serotonin 5HT 2C receptor antagonism, was found effective in the treatment of depressed patients. However, long-term safety studies are lacking for both melatonin agonists, particularly considering the pharmacological activity of their metabolites. In view of the higher binding affinities, longest half-life and relative higher potencies of the different melatonin agonists, studies using 2 or 3 mg/day of melatonin are probably unsuitable to give appropriate comparison of the effects of the natural compound. Hence, clinical trials employing melatonin doses in the range of 50-100 mg/day are warranted before the relative merits of the melatonin analogs versus melatonin can be settled. © 2011 John Wiley & Sons A/S.

Martinez E.,National University of Salta | Mejia R.,University of Buenos Aires | Perez-Stable E.J.,University of California at San Francisco
Tobacco Control | Year: 2015

Objective: To estimate the long-term and short-term effects on cigarette demand in Argentina based on changes in cigarette price and income per person >14 years old.Method: Public data from the Ministry of Economics and Production were analysed based on monthly time series data between 1994 and 2010. The econometric analysis used cigarette consumption per person >14 years of age as the dependent variable and the real income per person >14 years old and the real average price of cigarettes as independent variables. Empirical analyses were done to verify the order of integration of the variables, to test for cointegration to capture the long-term effects and to capture the short-term dynamics of the variables.Results: The demand for cigarettes in Argentina was affected by changes in real income and the real average price of cigarettes. The long-term income elasticity was equal to 0.43, while the own-price elasticity was equal to −0.31, indicating a 10% increase in the growth of real income led to an increase in cigarette consumption of 4.3% and a 10% increase in the price produced a fall of 3.1% in cigarette consumption. The vector error correction model estimated that the short-term income elasticity was 0.25 and the short-term own-price elasticity of cigarette demand was −0.15. A simulation exercise showed that increasing the price of cigarettes by 110% would maximise revenues and result in a potentially large decrease in total cigarette consumption.Conclusion: Econometric analyses of cigarette consumption and their relationship with cigarette price and income can provide valuable information for developing cigarette price policy. © 2015, BMJ Publishing Group. All rights reserved.

Ferraro R.,Institute Astronomia Y Fisica del Espacio | Ferraro R.,University of Buenos Aires
AIP Conference Proceedings | Year: 2012

We briefly review f(R) theories, both in the metric and Palatini formulations, their scalar-tensor representations and the chameleon mechanism that could explain the absence of perceptible consequences in the Solar System. We also review f(T) theories, a different approach to modified gravity consisting in a deformation of the teleparallel equivalent of General Relativity. We show some applications to cosmology and cosmic strings. As f(R)'s, f(T) theories are not exempted from additional degrees of freedom; we also discuss this still open issue. © 2012 American Institute of Physics.

Mazzei M.E.,University of Buenos Aires | Richeldi L.,University of Southampton | Collard H.R.,University of California at San Francisco
Therapeutic Advances in Respiratory Disease | Year: 2015

Idiopathic pulmonary fibrosis (IPF) is a progressive and ultimately fatal lung disease that occurs in older adults. The clinical course of IPF is variable and hard to predict in an individual patient. Nintedanib is a tyrosine kinase inhibitor that has recently been approved in the US and European Union for the treatment of IPF. Preclinical studies have shown that nintedanib interferes with processes active in fibrosis such as fibroblast proliferation, migration and differentiation and the secretion of extracellular matrix. The safety and efficacy of nintedanib have been investigated in the phase II TOMORROW trial and in two replicate 52-week randomized, placebo-controlled phase III trials known as the INPULSIS trials. These trials demonstrated that nintedanib slowed disease progression by reducing the annual rate of decline in forced vital capacity, with a manageable side-effect profile. In this review, we summarize key data supporting nintedanib as a treatment for patients with IPF and address key questions regarding the use of nintedanib in the clinical setting. © The Author(s), 2015.

Penna I.M.,University of Buenos Aires | Hermanns R.L.,Norges Geologiske Undersokelse | Niedermann S.,Helmholtz Center Potsdam | Folguera A.,University of Buenos Aires
Bulletin of the Geological Society of America | Year: 2011

Quaternary tectonic activity in the transition area between the Central and Patagonian Andes is closely associated with an anomalous cluster of rockslides: 19 rockslides with volumes up to 4 × 109 m3 developed in plateau basalts. We divided them into two groups: (A) rockslides related to neotectonic activity and (B) rockslides not related to neotectonic activity. Thirteen rockslides, with a total volume of ~10 km3, which lie on either folds or faults, have been displaced parallel to the structures and perpendicular to the valleyaxis, and they exhibit headscarps several kilometersaway from the valley axis. Most of them are larger than 109 m3, and are generally of rock avalanche type with a high degree of crushing of rocks, although local relief in some cases does not exceed 200 m. Nine rockslides with a total volume of 8.9 km3 are related to folds, while four with a total volume of 1.3 km3 are related to faults. The six rockslides not related to neotectonic activity have a totalvolume of 0.25 km3 (of which the largest one accounts for 0.17 km3), and are rotational slides and block topples with a low degree of rock fragmentation, although local relief is up to 400 m. The 3He and 21Ne surface exposure ages for six of these slides, as well as relative age assessment based on stratigraphic relation with glacial deposits and the drainage development on the rockslide deposit, suggest that the rockslide ages spread rather randomly betweenpre-glacial and mid Holocene, discarding climatic conditions as a common triggering factor. The absence of structures that can represent ideal sliding planes shows that rock fracturing due to neotectonic activity is a major conditioning factor for failures and that the magnitude of landslides is strongly controlled by the type of deformation. © 2011 Geological Society of America.

Massaferro J.,CONICET | Recasens C.,University of Geneva | Larocque-Tobler I.,LimnoPaleoServ | Zolitschka B.,University of Bremen | Maidana N.I.,University of Buenos Aires
Quaternary Science Reviews | Year: 2013

Laguna Potrok Aike is a maar lake located in southernmost Argentina and is one of the few permanent lakes preserving a continuous climatic record from the semiarid Patagonian steppe. Furthermore, its location close to Antarctica provides a unique opportunity to compare paleoclimate from continental South America with the polar records. The analysis of subfossil chironomids and diatoms throughout a 16-m sedimentary record retrieved from this lake, combined with a well-constrained chronology of the last ca 16ka BP, provided a high resolution paleoenvironmental reconstruction of the limnology of the lake and regional climate conditions. The combination of both bioproxies showed humid conditions during the Lateglacial, followed by drier conditions during the Holocene, resulting in large variations in lake level. Despite not showing a clear evidence of a cold reversal similar to the Antarctic Cold Reversal and/or the Younger Dryas, both records suggest high water levels and oligotrophic conditions between 16.4 and 11.5 cal. ka BP. The lake level drop that occurred at ca 8.7ka BP is well documented by both bioproxies. © 2012 Elsevier Ltd.

Areco M.M.,University of Buenos Aires | Hanela S.,Instituto Nacional del Agua | Duran J.,Instituto Nacional del Agua | dos Santos Afonso M.,University of Buenos Aires
Journal of Hazardous Materials | Year: 2012

Many industries have high heavy metals concentrations in their effluents that should be treated before disposal in drains or natural watercourses. When adsorption process is evaluated to generate and implement an efficient, economical and sustainable method suitable for heavy metals removal from contaminated effluents, it is necessary to develop an experimental setup that contains the adsorbent. Ulva lactuca, a marine green alga, was studied as a natural biosorbent for heavy metals at acid pH conditions. Adsorption experiments were carried out in glass columns and in batch where the alga was suspended or fixed in an agar matrix. Langmuir and Freundlich models were applied to the experimental results. Langmuir model best describes the adsorption isotherms in all analyzed cases. The adsorption capacity increases with pH. Kinetic studies demonstrate that, in most studied cases, the adsorption follows a pseudo second order kinetics model. Removal efficiencies of the biomaterial supported in agar or fixed in columns were: fixed in columns > suspended in batch mode > fixed in agar. Finally, the effect of the presence of two sorbates, Cd and Pb, in the solution was measured and results demonstrate that adsorption of both metals are diminished by co/adsorption. © 2012 Elsevier B.V.

De Florian D.,University of Buenos Aires | Sassot R.,University of Buenos Aires | Stratmann M.,Brookhaven National Laboratory | Vogelsang W.,University of Tübingen
Progress in Particle and Nuclear Physics | Year: 2012

We discuss some recent developments concerning the nucleon's helicity parton distribution functions: new preliminary data from jet production at RHIC suggest for the first time a non-vanishing polarization of gluons in the nucleon. SIDIS measurements at COMPASS provide better constraints on the strange and light sea quark helicity distributions. Single-longitudinal spin asymmetries in W-boson production have been observed at RHIC and will ultimately give new insights into the light quark and anti-quark helicity structure of the nucleon. © 2012 Elsevier B.V. All rights reserved.

Sookoian S.,University of Buenos Aires | Castano G.O.,Hospital Abel Zubizarreta | Scian R.,University of Buenos Aires | Mallardi P.,Hospital Diego Thompson | And 4 more authors.
Hepatology | Year: 2015

We explored the role of transmembrane 6 superfamily member 2 (TM6SF2) rs58542926 C/T nonsynonymous (p.Glu167Lys) variant in genetic susceptibility to nonalcoholic fatty liver disease (NAFLD) and disease severity. A total of 361 individuals (135 control subjects and 226 patients with histologically proven NAFLD) were included in a sample with 97% power for the additive genetic model. A discrete trait analysis of NAFLD showed that rs58542926 was associated with a modest risk of fatty liver (P=0.038; odds ratio [OR]: 1.37; 95% confidence interval [CI]: 1.02-1.84); nevertheless, conditioning on patatin-like phospholipase domain-containing 3 (PNPLA3)-rs738409 abolished this effect. We did not observe an interaction between rs738409 and rs58542926 variants on the risk of NAFLD. We observed a significant association of rs58542926 and disease severity (P=0.027), but not lobular inflammation or fibrosis; rs58542926 was not associated with levels of liver enzymes. An allelic test showed that the T (Lys167) allele was significantly associated with disease progression (P=0.021; OR, 1.66; 95% CI: 1.08-2.55). A significant association was found with the histological degree of liver steatosis (β, 0.15; standard error: 0.06; P=0.0299) that was independent of rs738409. Homozygous carriers of the C (Glu167) allele showed increased risk for cardiovascular disease. TM6SF2 protein expression was decreased markedly in liver of NAFLD patients, compared to controls. In addition, TM6SF2 immunoreactivity was reduced in subjects carrying at least one copy of the T allele, consistent with a difference in liver allele-specific transcript abundance. Conclusion: rs58542926 is a low-frequency variant with a modest effect on NAFLD, suggesting that carriers of the T allele are slightly more likely to accumulate fat in the liver and develop nonalcoholic steatohepatitis than those without. TM6SF2 appears to play a significant role in disease biology. © 2014 by the American Association for the Study of Liver Diseases.

Filippini S.E.,Institute of Legal Medicine and Genomic Medicine Group | Filippini S.E.,University of Buenos Aires | Vega A.,CIBER ISCIII
Frontiers in Bioscience | Year: 2013

Breast cancer (BC) is a heterogeneous disease. The majority of breast cancer cases (about 70 percent) are considered sporadic. Familial breast cancer (about 30 percent of patients), often seen in families with a high incidence of BC, has been associated with a number of high-, moderate-, and low-penetrance susceptibility genes. Family linkage studies have identified high-penetrance genes, BRCA1, BRCA2, PTEN and TP53, that are responsible for inherited syndromes. Moreover, a combination of family-based and population-based approaches indicated that genes involved in DNA repair, such as CHEK2, ATM, BRIP1 (FANCJ), PALB2 (FANCN) and RAD51C (FANCO), are associated with moderate BC risk. Genome wide association studies (GWAS) in BC revealed a number of common low penetrance alleles associated with a slightly increased or decreased risk of BC. Currently, only high penetrance genes are used in clinical practice on a wide scale. Due to the development of next generation sequencing technologies, it is envisaged that all familial breast cancer genes will be included in the genetic test. However, additional research in clinical management of moderate and low-risk variants is needed before full implementation of multi-gene panel testing into clinical work-flows. In this review, we focus on the different components of familial breast cancer risk.

Giribet G.,University of Buenos Aires | Giribet G.,Pontifical Catholic University of Valparaíso | Vasquez Y.,University of La Serena
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2015

Minimal massive gravity (MMG) is an extension of three-dimensional topologically massive gravity that, when formulated about anti-de Sitter space, accomplishes solving the tension between bulk and boundary unitarity that other models in three dimensions suffer from. We study this theory at the chiral point, i.e. at the point of the parameter space where one of the central charges of the dual conformal field theory vanishes. We investigate the nonlinear regime of the theory, meaning that we study exact solutions to the MMG field equations that are not Einstein manifolds. We exhibit a large class of solutions of this type, which behave asymptotically in different manners. In particular, we find analytic solutions that represent two-parameter deformations of extremal Bañados-Teitelboim-Zanelli black holes. These geometries behave asymptotically as solutions of the so-called log gravity, and, despite the weakened falling off close to the boundary, they have finite mass and finite angular momentum, which we compute. We also find time-dependent deformations of Bañados-Teitelboim-Zanelli that obey Brown-Henneaux asymptotic boundary conditions. The existence of such solutions shows that the Birkhoff theorem does not hold in MMG at the chiral point. Other peculiar features of the theory at the chiral point, such as the degeneracy it exhibits in the decoupling limit, are discussed. © 2015 American Physical Society.

Devoto M.,University of Buenos Aires | Bailey S.,Forestry Commission | Memmott J.,University of Bristol
Ecological Entomology | Year: 2011

Diurnal plant-visitor networks are well studied, but the community-level dimension of nocturnal visitation by insects has been largely overlooked.This study focused on the role of moths as pollen vectors in a boreal pine forest in Scotland. Light traps were used to sample moths in 20 plots in two consecutive years. The pollen on moths' bodies was identified and pollen grains counted. This information was used to build a nocturnal pollen-transport network for each year. These are the first networks to characterise a nocturnal plant-visitor community.A total of 4162 moths belonging to 103 species were captured; 25 moth species were found to carry pollen of 12 plant taxa. Adding nocturnal data to diurnal networks increased number of plant taxa, insect species, and unique interactions in the network.Despite differences in species composition, nocturnal networks exhibit similar properties to diurnal networks: significant nestedness, marked asymmetry of interactions, high dependence on a core of generalists, and high inter-annual variation in species abundances and occurrence of interactions.Traditional diurnal plant-visitor networks exclude a significant component of the community, i.e. nocturnal visitors. Exploring links across boundaries between networks (such as between diurnal and nocturnal networks) will provide a more accurate picture of ecosystem structure and function. © 2010 The Authors. Ecological Entomology © 2010 The Royal Entomological Society.

Orellana L.,University of Buenos Aires | Rotnitzky A.,Torcuato Di Tella University | Robins J.M.,Harvard University
International Journal of Biostatistics | Year: 2010

Dynamic treatment regimes are set rules for sequential decision making based on patient covariate history. Observational studies are well suited for the investigation of the effects of dynamic treatment regimes because of the variability in treatment decisions found in them. This variability exists because different physicians make different decisions in the face of similar patient histories. In this article we describe an approach to estimate the optimal dynamic treatment regime among a set of enforceable regimes. This set is comprised by regimes defined by simple rules based on a subset of past information. The regimes in the set are indexed by a Euclidean vector. The optimal regime is the one that maximizes the expected counterfactual utility over all regimes in the set. We discuss assumptions under which it is possible to identify the optimal regime from observational longitudinal data. Murphy et al. (2001) developed efficient augmented inverse probability weighted estimators of the expected utility of one fixed regime. Our methods are based on an extension of the marginal structural mean model of Robins (1998, 1999) which incorporate the estimation ideas of Murphy et al. (2001). Our models, which we call dynamic regime marginal structural mean models, are specially suitable for estimating the optimal treatment regime in a moderately small class of enforceable regimes of interest. We consider both parametric and semiparametric dynamic regime marginal structural models. We discuss locally efficient, double-robust estimation of the model parameters and of the index of the optimal treatment regime in the set. In a companion paper in this issue of the journal we provide proofs of the main results. © 2010 The Berkeley Electronic Press. All rights reserved.

Vucicevic J.,University of Belgrade | Tanaskovic D.,University of Belgrade | Rozenberg M.J.,University Paris - Sud | Rozenberg M.J.,University of Buenos Aires | Dobrosavljevic V.,Florida State University
Physical Review Letters | Year: 2015

Bad-metal (BM) behavior featuring linear temperature dependence of the resistivity extending to well above the Mott-Ioffe-Regel (MIR) limit is often viewed as one of the key unresolved signatures of strong correlation. Here we associate the BM behavior with the Mott quantum criticality by examining a fully frustrated Hubbard model where all long-range magnetic orders are suppressed, and the Mott problem can be rigorously solved through dynamical mean-field theory. We show that for the doped Mott insulator regime, the coexistence dome and the associated first-order Mott metal-insulator transition are confined to extremely low temperatures, while clear signatures of Mott quantum criticality emerge across much of the phase diagram. Remarkable scaling behavior is identified for the entire family of resistivity curves, with a quantum critical region covering the entire BM regime, providing not only insight, but also quantitative understanding around the MIR limit, in agreement with the available experiments. © 2015 American Physical Society.

Sokolov D.A.,University of Notre Dame | Morozov Y.V.,University of Notre Dame | Morozov Y.V.,Taras Shevchenko National University | McDonald M.P.,University of Notre Dame | And 3 more authors.
Nano Letters | Year: 2014

Laser reduction of graphene oxide (GO) offers unique opportunities for the rapid, nonchemical production of graphene. By tuning relevant reduction parameters, the band gap and conductivity of reduced GO can be precisely controlled. In situ monitoring of single layer GO reduction is therefore essential. In this report, we show the direct observation of laser-induced, single layer GO reduction through correlated changes to its absorption and emission. Absorption/emission movies illustrate the initial stages of single layer GO reduction, its transition to reduced-GO (rGO) as well as its subsequent decomposition upon prolonged laser illumination. These studies reveal GO's photoreduction life cycle and through it native GO/rGO absorption coefficients, their intrasheet distributions as well as their spatial heterogeneities. Extracted absorption coefficients for unreduced GO are α405 nm ≈ 6.5 ± 1.1 × 104 cm-1, α 520 nm ≈ 2.1 ± 0.4 × 104 cm-1, and α640 nm ≈ 1.1 ± 0.3 × 104 cm-1 while corresponding rGO α-values are α 405 nm ≈ 21.6 ± 0.6 × 104 cm-1, α520 nm ≈ 16.9 ± 0.4 × 104 cm -1, and α640 nm ≈ 14.5 ± 0.4 × 104 cm-1. More importantly, the correlated absorption/emission imaging provides us with unprecedented insight into GO's underlying photoreduction mechanism, given our ability to spatially resolve its kinetics and to connect local rate constants to activation energies. On a broader level, the developed absorption imaging is general and can be applied toward investigating the optical properties of other two-dimensional materials, especially those that are nonemissive and are invisible to current single molecule optical techniques. © 2014 American Chemical Society.

Gunthard H.F.,University of Zürich | Aberg J.A.,Mount Sinai School of Medicine | Eron J.J.,University of North Carolina at Chapel Hill | Hoy J.F.,Monash University | And 11 more authors.
JAMA - Journal of the American Medical Association | Year: 2014

IMPORTANCE: New data and antiretroviral regimens expand treatment choices in resource-rich settings and warrant an update of recommendations to treat adults infected with human immunodeficiency virus (HIV). OBJECTIVE: To provide updated treatment recommendations for adults with HIV, emphasizing when to start treatment; what treatment to start; the use of laboratory monitoring tools; and managing treatment failure, switches, and simplification. DATA SOURCES, STUDY SELECTION, AND DATA SYNTHESIS: An International Antiviral Society-USA panel of experts in HIV research and patient care considered previous data and reviewed new data since the 2012 update with literature searches in PubMed and EMBASE through June 2014. Recommendations and ratings were based on the quality of evidence and consensus. RESULTS: Antiretroviral therapy is recommended for all adults with HIV infection. Evidence for benefits of treatment and quality of available data increase at lower CD4 cell counts. Recommended initial regimens include 2 nucleoside reverse transcriptase inhibitors (NRTIs; abacavir/lamivudine or tenofovir disoproxil fumarate/emtricitabine) and a third single or boosted drug, which should be an integrase strand transfer inhibitor (dolutegravir, elvitegravir, or raltegravir), a nonnucleoside reverse transcriptase inhibitor (efavirenz or rilpivirine) or a boosted protease inhibitor (darunavir or atazanavir). Alternative regimens are available. Boosted protease inhibitor monotherapy is generally not recommended, but NRTI-sparing approachesmay be considered. New guidance for optimal timing of monitoring of laboratory parameters is provided. Suspected treatment failure warrants rapid confirmation, performance of resistance testing while the patient is receiving the failing regimen, and evaluation of reasons for failure before consideration of switching therapy. Regimen switches for adverse effects, convenience, or to reduce costs should not jeopardize antiretroviral potency. CONCLUSIONS AND RELEVANCE: After confirmed diagnosis of HIV infection, antiretroviral therapy should be initiated in all individuals who are willing and ready to start treatment. Regimens should be selected or changed based on resistance test results with consideration of dosing frequency, pill burden, adverse toxic effect profiles, comorbidities, and drug interactions. Copyright 2014 American Medical Association. All rights reserved.

Gershanik O.,University of Buenos Aires | Jenner P.,King's College London
European Journal of Neurology | Year: 2012

Motor fluctuations and motor complications are a major consequence of the treatment and progression of Parkinson's disease (PD) and they have, in particular, been linked to l-dopa therapy. Using continuous dopaminergic stimulation (CDS) by employing longer acting dopaminergic drugs has been proposed as a means of avoiding or lowering their occurrence. However, both the preclinical and clinical evidence base suggest that this concept does not fully explain the differences between l-dopa and dopamine (DA) agonist drugs and that their pharmacological profiles may also be important. In addition, the way in which drugs are delivered in PD appears to have a marked influence on both efficacy and side-effect profile. As a consequence, the concept of continuous drug delivery (CDD) has arisen to explain the differences between the intermittent and continuous delivery of both l-dopa and DA agonists. This review presents the evidence for using CDD as a working concept for the early and later stages of PD and in the treatment of motor complications and motor fluctuations. CDD as an approach to the treatment of PD may improve the outcome of therapy and explain the differences between drug classes and the delivery systems employed. © 2012 The Author(s) European Journal of Neurology © 2012 EFNS.

Amarilla L.,University of Buenos Aires | Eiroa E.F.,University of Buenos Aires | Eiroa E.F.,Institute Astronomia y Fisica Del Espacio
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2013

We study the shadow produced by a spinning Kaluza-Klein black hole in Einstein gravity coupled to a Maxwell field and a dilaton. The size and the shape of the shadow depend on the mass, the charge, and the angular momentum. We find that, for fixed values of these parameters, the shadow is slightly larger and less deformed than for its Kerr-Newman counterpart. © 2013 American Physical Society.

Josso N.,University Paris - Sud | Rey R.,CONICET | Rey R.,University of Buenos Aires | Picard J.-Y.,University Paris - Sud
Seminars in Reproductive Medicine | Year: 2012

Male fetal sexual differentiation of the genitalia is driven by Leydig cell-secreted androgens and Sertoli cell-secreted anti-Müllerian hormone (AMH). Disorders of sex development (DSD) may be due to abnormal morphogenesis of genital primordia or to defective testicular hormone secretion or action. In dysgenetic DSD, due to an early fetal-onset primary hypogonadism affecting Leydig and Sertoli cells, the fetal gonads are incapable of producing normal levels of androgens and AMH. In non-dysgenetic DSD, either Leydig cells or Sertoli cells are affected but not both. Persistent Müllerian duct syndrome (PMDS) may result from Sertoli cell-specific dysfunction due to mutations in the AMH gene; these patients have Fallopian tubes and uterus, but male external genitalia. In DSD due to insensitivity to testicular hormones, fetal Leydig and Sertoli cell function is normal. Defective androgen action is associated with female or ambiguous genitalia whereas insensitivity to AMH results in PMDS with normal serum AMH. Clinical and biological features of PMDS due to mutations in the genes coding for AMH or the AMH receptor, as well as genetic aspects and clinical management are discussed. © 2012 by Thieme MedicalPublishers, Inc., 333 Seventh Avenue,New York, NY 10001, USA.

Khan I.M.,Aligarh Muslim University | Ahmad A.,Aligarh Muslim University | Kumar S.,University of Buenos Aires
Journal of Molecular Structure | Year: 2013

A new charge transfer (CT) complex [(DAPH)+(DNB)-] consisting of 2,6-diaminopyridine (DAP) as donor and 3,5-dinitrobenzoic acid (DNB-H) as acceptor, was synthesized and characterized by FTIR, 1H and 13C NMR, ESI mass spectroscopic and X-ray crystallographic techniques. The hydrogen bonding (N+-H⋯O-) plays an important role to consolidate the cation and anion together. CT complex shows a considerable interaction with Calf thymus DNA. The CT complex was also tested for its antibacterial activity against two Gram-positive bacteria Staphylococcus aureus and Bacillus subtilis and two Gram-negative bacteria Escherichia coli and Pseudomonas aeruginosa strains by using Tetracycline as standard, and antifungal property against Aspergillus niger, Candida albicans, and Penicillium sp. by using Nystatin as standard. The results were compared with standard drugs and significant conclusions were obtained. A polymeric net work through H-bonding interactions between neighboring moieties was observed. This has been attributed to the formation of 1:1 type CT complex. © 2012 Elsevier B.V. All rights reserved.

Ivanov V.A.,University of Buenos Aires | Caira J.N.,University of Connecticut
Journal of Parasitology | Year: 2012

Three new species of diphyllidean cestodes are described from rhinobatid elasmobranchs of the genus Glaucostegus from the Indian and Pacific Oceans. All 3 new species have 11 apical hooks (6 type-A and 5 type-B hooks) and, therefore, differ in this feature from all but 5 of the 39 valid species of Echinobothrium. In addition, Echinobothrium tetabuanense n. sp. from Glaucostegus cf. typus in the Sulu Sea, Borneo differs from all of its congeners in the number and arrangement of hooklets, number of spines on the cephalic peduncle, and the number and distribution of testes. Echinobothrium sematanense n. sp. from Glaucostegus thouin in the South China Sea, Borneo, can be distinguished from its congeners based on the following combination of characters, i.e., small size (worms less than 1 mm long), number of hooklets, spines per column on the cephalic peduncle, and number of testes. Echinobothrium weipaense n. sp. from northern Australia is unique in the position of the cirrus sac and genital pore, both structures being well posterior and not overlapping the ovary. An emended description of the microthrix pattern on the scolex of Echinobothrium chisholmae from G. typus in Australia is also presented. © 2012 American Society of Parasitologists.

Ballare C.L.,University of Buenos Aires | Caldwell M.M.,Utah State University | Flint S.D.,Utah State University | Robinson S.A.,University of Wollongong | Bornman J.F.,University of Waikato
Photochemical and Photobiological Sciences | Year: 2011

Ultraviolet radiation (UV) is a minor fraction of the solar spectrum reaching the ground surface. In this assessment we summarize the results of previous work on the effects of the UV-B component (280-315 nm) on terrestrial ecosystems, and draw attention to important knowledge gaps in our understanding of the interactive effects of UV radiation and climate change. We highlight the following points: (i) The effects of UV-B on the growth of terrestrial plants are relatively small and, because the Montreal Protocol has been successful in limiting ozone depletion, the reduction in plant growth caused by increased UV-B radiation in areas affected by ozone decline since 1980 is unlikely to have exceeded 6%. (ii) Solar UV-B radiation has large direct and indirect (plant-mediated) effects on canopy arthropods and microorganisms. Therefore, trophic interactions (herbivory, decomposition) in terrestrial ecosystems appear to be sensitive to variations in UV-B irradiance. (iii) Future variations in UV radiation resulting from changes in climate and land-use may have more important consequences on terrestrial ecosystems than the changes in UV caused by ozone depletion. This is because the resulting changes in UV radiation may affect a greater range of ecosystems, and will not be restricted solely to the UV-B component. (iv) Several ecosystem processes that are not particularly sensitive to UV-B radiation can be strongly affected by UV-A (315-400 nm) radiation. One example is the physical degradation of plant litter. Increased photodegradation (in response to reduced cloudiness or canopy cover) will lead to increased carbon release to the atmosphere via direct and indirect mechanisms. © 2011 The Royal Society of Chemistry and Owner Societies.

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.

Valeri C.,Hospital Of Ninos Ricardo Gutierrez | Schteingart H.F.,Hospital Of Ninos Ricardo Gutierrez | Rey R.A.,Hospital Of Ninos Ricardo Gutierrez | Rey R.A.,University of Buenos Aires
Current Opinion in Endocrinology, Diabetes and Obesity | Year: 2013

Purpose of review: Biomarkers of prepubertal testicular function have become widely available only in recent years. The aim of this review is to update the knowledge on key biomarkers used to assess hypogonadism in boys. Recent findings: Sertoli cells are the most representative cells of the prepubertal testis. Anti-Müllerian hormone and inhibin B are essential biomarkers of Sertoli cell function. Also, INSL3 arises as an additional marker of Leydig cell dysfunction. Summary: The widespread use of these biomarkers has enhanced our knowledge on the pathophysiology and diagnosis of prepubertal male hypogonadism. Beyond their well known germ-cell toxicity, oncologic treatments may also affect Sertoli cell function. Pathophysiology is not the same in all aneuploidies leading to infertility: while hypogonadism is not evident until mid-puberty in Klinefelter syndrome, it is established in early infancy in Down syndrome. In Noonan syndrome, the occurrence of primary hypogonadism depends on the existence of cryptorchidism, and Prader-Willi syndrome may present with either primary or combined forms of hypogonadism. Prepubertal testicular markers have also provided insights into the effects of environmental disruptors on gonadal function from early life, and helped dissipate concerns about testicular function in boys born preterm or small for gestational age or conceived by assisted reproductive technique procedures. © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins.

Goddard L.,Columbia University | Hurrell J.W.,U.S. National Center for Atmospheric Research | Kirtman B.P.,University of Miami | Murphy J.,UK Met Office | And 2 more authors.
Bulletin of the American Meteorological Society | Year: 2012

Although differences exist between seasonal- and decadal-scale climate variability, predictability, and prediction, investment in observations, prediction systems, and decision systems for either time scale can benefit both. © 2012 American Meteorological Society.

Bilgin D.D.,University of Illinois at Urbana - Champaign | Zavala J.A.,University of Buenos Aires | Zhu J.,University of Illinois at Urbana - Champaign | Clough S.J.,University of Illinois at Urbana - Champaign | And 2 more authors.
Plant, Cell and Environment | Year: 2010

To determine if damage to foliage by biotic agents, including arthropods, fungi, bacteria and viral pathogens, universally downregulates the expression of genes involved in photosynthesis, we compared transcriptome data from microarray experiments after twenty two different forms of biotic damage on eight different plant species. Transcript levels of photosynthesis light reaction, carbon reduction cycle and pigment synthesis genes decreased regardless of the type of biotic attack. The corresponding upregulation of genes coding for the synthesis of jasmonic acid and those involved in the responses to salicylic acid and ethylene suggest that the downregulation of photosynthesis-related genes was part of a defence response. Analysis of the sub-cellular targeting of co-expressed gene clusters revealed that the transcript levels of 84% of the genes that carry a chloroplast targeting peptide sequence decreased. The majority of these downregulated genes shared common regulatory elements, such as G-box (CACGTG), T-box (ACTTTG) and SORLIP (GCCAC) motifs. Strong convergence in the response of transcription suggests that the universal downregulation of photosynthesis-related gene expression is an adaptive response to biotic attack. We hypothesize that slow turnover of many photosynthetic proteins allows plants to invest resources in immediate defence needs without debilitating near term losses in photosynthetic capacity. © 2010 Blackwell Publishing Ltd.

Zurita G.A.,University of Buenos Aires | Zurita G.A.,National University of Misiones | Bellocq M.I.,University of Buenos Aires
Biotropica | Year: 2012

Traditional approaches to the study of species persistence in fragmented landscapes generally consider a binary classification of habitat being suitable or unsuitable; however, the range of human-modified habitats within a region may offer a gradient of habitat suitability (or conservation value) for species. We identified such a gradient by comparing bird assemblages among contrasting land uses (pine plantations of different age, annual crops, clear cuts and cattle pastures) in the Upper Parana Atlantic forest. Bird assemblages and vegetation structure were characterized in an extensive area of 4400 km 2 in Argentina and Paraguay during the breeding seasons of 2005-2010. Similarity of bird assemblages between anthropogenic habitats and the native forest and the proportion of forest species increased with vegetation vertical structure, while the proportion of open-area species decreased. As a consequence, mature tree plantations were the most suitable habitats for forest species and were mainly used by frugivores and bark insectivores. In contrast, open habitats were the least suitable habitat for forest species and were used primarily by insectivores. Human-created habitats that are structurally complex can be used by a subset of forest species, and may improve functional connectivity and mitigate edge effects. The conservation of large tracks of native forests, however, is critical for the long-term persistence of the entire bird assemblage, especially for native forest dependent species. © 2011 by The Association for Tropical Biology and Conservation.

Chimento L.P.,University of the Basque Country | Chimento L.P.,Ikerbasque | Chimento L.P.,University of Buenos Aires
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2010

We investigate models of interacting dark matter and dark energy for the Universe in a spatially flat Friedmann-Robertson-Walker space-time. We find the "source equation" for the total energy density and determine the energy density of each dark component. We introduce an effective one-fluid description to evidence that interacting and unified models are related to each other, analyze the effective model, and obtain the attractor solutions. We study linear and nonlinear interactions, the former comprises a linear combination of the dark matter and dark energy densities, their first derivatives, the total energy density, its first and second derivatives, and a function of the scale factor. The latter is a possible generalization of the linear interaction consisting of an aggregate of the above linear combination and a significant nonlinear term built with a rational function of the dark matter and dark energy densities homogeneous of degree 1. We solve the evolution equations of the dark components for both interactions and examine exhaustively several examples. There exist cases where the effective one-fluid description produces different alternatives to the ΛCDM model and cases where the problem of coincidence is alleviated. In addition, we find that some nonlinear interactions yield an effective one-fluid model with a Chaplygin gas equation of state, whereas others generate cosmological models with de Sitter and power-law expansions. We show that a generic nonlinear interaction induces an effective equation of state which depends on the scale factor in the same way as the variable modified Chaplygin gas model, giving rise to the "relaxed Chaplygin gas model." © 2010 The American Physical Society.

Ferraro R.,Institute Astronomia y Fisica del Espacio | Ferraro R.,University of Buenos Aires | Fiorini F.,Institute Astronomia y Fisica del Espacio
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2011

Some conceptual issues concerning f(T) theories - a family of modified gravity theories based on absolute parallelism - are analyzed. Due to the lack of local Lorentz invariance, the autoparallel frames satisfying the field equations are evasive to an a priori physical understanding. We exemplify this point by working out the vierbein (tetrad) fields for closed and open Friedmann-Robertson-Walker cosmologies. © 2011 Elsevier B.V.

Ferraro R.,Institute Astronomia y Fisica Del Espacio | Ferraro R.,University of Buenos Aires
Journal of High Energy Physics | Year: 2013

The non-linear second order Born-Infeld equation is reduced to a simpler first order complex equation, which can be trivially solved for the coordinates as functions of the field. Each solution is determined by the choice of a holomorphic function subjected to boundary conditions. The explanation of the method is accompanied by applications to Born-Infeld electrostatics, magnetostatics and wave propagation. © 2013 SISSA, Trieste, Italy.

Arrachea L.,University of Buenos Aires | Fradkin E.,University of Illinois at Urbana - Champaign
Physical Review B - Condensed Matter and Materials Physics | Year: 2011

We consider a model for an edge state of electronic systems in the quantum Hall regime with filling ν=1 and in the quantum spin Hall regime. In both cases, the system is in contact with two reservoirs by tunneling at point contacts. Both systems are locally driven by applying an ac voltage in one of the contacts. By weakly coupling them to a third reservoir, the transport of the generated heat is studied in two different ways: (i) when the third reservoir acts as a thermometer, the local temperature is sensed and (ii) when the third reservoir acts as a voltage probe, the time-dependent local voltage is sensed. Our results indicate a chiral propagation of the heat along the edge in the quantum Hall and in the quantum spin Hall cases (if the injected electrons are spin polarized). We also show that a analogous picture is obtained if instead of heating by ac driving the system is put in contact to a stationary reservoir at a higher temperature. In both cases, the temperature profile shows that the electrons along the edge thermalize with the closest "upstream" reservoir. © 2011 American Physical Society.

Muler N.,Torcuato Di Tella University | Yohai V.J.,University of Buenos Aires
Computational Statistics and Data Analysis | Year: 2013

A new class of robust estimators for VAR models is introduced. These estimators are an extension to the multivariate case of the MM-estimators based on a bounded innovation propagation AR model. They have a filtering mechanism that avoids the propagation of the effect of one outlier to the residuals of the subsequent periods. Besides, they are consistent and have the same asymptotic normal distribution as regular MM-estimators for VAR models. A Monte Carlo study shows that these estimators compare favorable with respect to other robust ones. © 2012 Elsevier B.V. All rights reserved.

Agency: European Commission | Branch: FP7 | Program: CP-IP | Phase: NMP-2007-2.1-1 | Award Amount: 8.23M | Year: 2008

Light composite materials for load bearing applications can be made using different type reinforcements and polymer matrices. Carbon nanotubes (CNT) have been studied extensively because of their exceptional mechanical and electrical properties, yet their practical and extensive use in commercial materials is missing. The utilization of CNTs as reinforcement to design novel composites is a quite old idea. However, there is a lack of a knowledge based approach to achieve the nanostructuration level required to optimize the CNT/polymer composite performances. The main objective of POCO is to get innovative polymer composites filled with CNT in order to obtain nanostructured materials with tailor made properties. The CNT/polymer interface is, together with the CNT and the polymer, the third and most important element that will determine the final properties. Hence the chemical functionalization of CNT surfaces is of utter importance to achieve not only a proper dispersion and anchorage of the nanotubes into the polymer matrix during processing, but also to optimize the performance itself in solid state. Our approach involves the development of different CNT confinement strategies to develop novel polymer matrix nanocomposites. Several polymers have been selected as representative of thermosetting and thermoplastic materials. This ensures that the output of POCO could be applied in a wide range of applications: automotive, aeronautics, building, aerospace, wind power generation (blades), ship building, biomedicineThis project will be focused on four fundamental properties: (i) high strength for structural and mechanical components, (ii) tuneable electrical properties, (iii) low wear under fretting (low amplitude reciprocating movement) and (iv) superhydrophobicity. Multifunctionality of these materials will be an important benefit as the requirements for composite polymeric materials are quite diverse

Agency: European Commission | Branch: FP7 | Program: MC-ITN | Phase: FP7-PEOPLE-2010-ITN | Award Amount: 4.49M | Year: 2011

The Large Hadron Collider (LHC) at CERN is the largest and most complex single experiment ever performed in the history of mankind. The physics program of the LHC is motivated by fundamental questions about the laws of nature, such as explaining the origin of mass, understanding the early universe and the structure of space and time, unravelling the nature of dark matter and providing glimpses of extra spatial dimensions or grand unification of forces. Any of these insights would definitely constitute a revolution in our view on the world. The LHCPhenoNet unites throughout Europe young and energetic leadership in theoretical particle physics with emphasis on LHC phenomenology. Most of its team and task leaders have made highly significant and innovative contributions in the last years within the theory of strong interactions, Quantum Chromodynamics (QCD), or the electroweak sector of the SM by addressing key issues at the interface to the experiments. The network members are poised to lead the theoretical particle physics community to meet the new challenges presented by LHC physics and to provide in a unified European effort excellent training for young theoretical physicists in this field, at both the doctoral and post-doctoral level. With the challenges of the machine operation driving the LHC start-up, the proposed timeline of the initial training network matches the currently foreseen LHC running schedule and thus allows full exploitation and interpretation of the early data. The field of theoretical particle physics is also currently driven by the development of customized open-source software as well as by applications of products from commercial enterprises especially in the field of symbolic manipulation and computer algebra, such as Maple and Mathematica from our private sector partners. The proposed network LHCPhenoNet is designed to provide optimal training conditions for early stage researchers in an interdisciplinary environment.

Agency: European Commission | Branch: FP7 | Program: CSA-SA | Phase: SiS-2007- | Award Amount: 814.10K | Year: 2008

Ecological economics (EE) and, in general, sustainability sciences make important contributions to the analyses of sustainability policies in Europe and worldwide. EE develops physical indicators and indices, provides economic valuation of environmental services and negative externalities, applies tools of multi-criteria evaluation to resource use, and promotes environmental policy instruments such as eco-taxes and marketable permits. To provide policy makers with high quality, relevant research, increased collaboration between ecological economists and CSOs is needed. Many CSOs already have a large stock of environmental knowledge but need increased capacity in EE to give an analytical foundation to activism and policy making. The social and disciplinary divide between CSO and academic research poses significant challenges. At the same time, there are real-world demands from CSOs for knowledge of EE for instance, to assess the liability of companies in oil extraction conflicts, to evaluate plans for palm oil plantations for biofuel exports, or to establish alternative energy plans at the regional level. This project addresses CSO capacity weakness in EE through a number of coordinated activities. The focus is not on theory but on case study learning. Joint working groups will identify and report on key issues for research in water management, mining, energy, forestry and agriculture, based on CSO needs and interests. Previous cooperative research activities will be reviewed and assessed in terms of their effectiveness in meeting CSO needs, and documented and disseminated. In addition, options for future research cooperation will be explored in order to apply EE methods, tools and indicators to CSO work. Findings will be presented and enhanced at symposia embedded in the 2008 EE world conference in Nairobi (with UNEP) and the 2009 conference of the European Society for EE. A website will disseminate the projects work and continue the capacity building process.

Ayala-Pena V.B.,National University of the South | Scolaro L.A.,University of Buenos Aires | Santillan G.E.,National University of the South
Experimental Cell Research | Year: 2013

The modulation of purinergic receptors plays an important role in the regulation of bone formation by the osteoblast. On the other hand, bone morphogenetic proteins (BMPs), members of the transforming growth factor-β superfamily, regulate the differentiation of osteoprogenitor bone cells and stimulate bone formation. In this study, we investigate the effects of several nucleotides on osteoblast differentiation and function, and their relation with the gene expression of osteogenic proteins BMP-2, BMP-4 and BMP-5 as well as of differentiation markers alkaline phosphatase (ALP) and bone sialoprotein (BSP). Our results indicate that 100μM ATP, ATPγS and UTP, but not ADP, ADPβS or UDP, promote ALP activity in rat primary osteoblasts, showing a peak about day 7 of the treatment. ATP, ATPγS and UTP also increase the mRNA levels of ALP, BMP-2, BMP-4, BMP-5 and BSP. Both the ALP activity and ALP and BMP-4 mRNA increments induced by ATP and UTP are inhibited by Ly294002, a PI3K inhibitor, suggesting the involvement of PI3K/AKT signaling pathway in purinergic modulation of osteoblast differentiation. Furthermore, bone mineralization enhance 1 and 1.5 fold after culturing osteoblasts in the presence of 100μM ATP or UTP, respectively, but not of ADP or UDP for 22 days. This information suggests that P2Y2 receptors (responsive to ATP, ATPγS and UTP) enhance osteoblast differentiation involving PI3K/AKT signaling pathway activation and gene expression induction of ALP, BMP-2, BMP-4, BMP-5 and BSP. Our findings state a novel molecular mechanism that involves specific gene expression activation of osteoblast function by the purinoreceptors, which would be of help in setting up new pharmacological strategies for the intervention in bone loss pathologies. © 2013 Elsevier Inc.

News Article | September 14, 2016
Site: www.nature.com

Early on a cold spring morning, Diana Wall is trying out a tool normally used to make holes on golf courses — and she can't contain her excitement. Her team has always used more laborious methods to take samples of soil and its resident organisms. “Oh, that's a beautiful core,” she says as one student bags a sample filled with tiny roundworms. “Hello, nematodes!” Wall, a soil ecologist and environmental scientist at Colorado State University in Fort Collins, has come to this site about an hour east of the campus to collect data for one of her latest experiments. She and her colleagues are creating an artificial drought in a patch of grassland by covering it with temporary shelters. They expect that predatory nematodes will die or enter a type of suspended animation, leaving the parasitic nematodes that prey on plants to dominate the ecosystem. “How do plants respond below-ground to drought?” she wonders. Wall has been asking — and answering — similar questions about soil for decades. She has become one of the most celebrated and outspoken experts on the hidden biodiversity in dirt, having studied soils and their inhabitants in nearly every corner of the world. She has a special fondness for Antarctica, which she has visited almost every year since 1989. It was there that she and a colleague made a landmark discovery, demonstrating that the soil in one of the driest spots on Earth is home to some animal life and not sterile, as many had thought. The same drive to challenge orthodoxy also helped her to advance in a field in which women were once rare. “Many times, I felt like I was hitting the glass ceiling and got discouraged,” she says, before emphasizing how things have improved. “Today, I love seeing so many women in Antarctic and other research.” Alongside her own experiments, Wall has become an ambassador for soil science and conservation — at a time when soil ecosystems are being devastated by forces such as erosion, pollution, pesticides and climate change. Soil degradation over the past two centuries or so has released billions of tonnes of stored carbon into the atmosphere, and this discharge could accelerate, speeding up climate change. Beyond that, says Wall, the threats to soil could jeopardize food production, water quality and the health of humans, plants and animals. The current path, she says, “leaves our terrestrial biodiverse world as we know it very uncertain”. The efforts of Wall and other scientists to raise the profile of soils have been making an impact. The United Nations declared 2015 the International Year of Soils, and in May, Wall travelled to Nairobi to launch the Global Soil Biodiversity Atlas — a compendium of information developed by a team of more than 100 scientists, which she helped to lead. David Montgomery, a geomorphologist at the University of Washington in Seattle, says that Wall has inspired many other researchers in their science and outreach on topics important to society. “We need more first-rate scientists willing to speak in those arenas.” This month, Wall is busy planning for her next trip to Antarctica, which will come, as usual, just after Christmas. Her colleagues joke that those journeys keep Wall young because she often crosses the International Date Line on her birthday, essentially erasing the day from the calendar. Assuming that she passes her physical — for which she is swimming and cycling — this trip will be her 27th to Antarctica. Wall is 72 and has seemingly boundless energy. Tall and thin, she speaks quickly and picks up the pace as she describes the zoo of organisms in soils, from nematodes to the vast array of microbes. She emphasizes how bacteria and other microorganisms provide services that humans take for granted: filtering water, stabilizing soil, improving air quality and recycling nutrients that enable crops to grow. “I like to think of it as this factory underground,” she says. Wall credits her mother, a biology teacher, with helping to spark a lifelong interest in biology. Raised in Lexington, Kentucky, Wall got her PhD in plant pathology from the University of Kentucky in her home town. In 1972, she left for the US west coast to pursue postgraduate research in nematology — convinced that nematode parasites had a lot to reveal about how life behaves above ground. California was a shock at first. “That was eye-opening to me, because I had never crossed the Mississippi River, and it was — oh my god, where are the trees?” she says. But she ended up liking it there, and the University of California, Riverside, remained her home for much of the next two decades. She strung together a series of grants to keep her work going, confident that soil microorganisms were more significant than most researchers realized. “Originally, I was just convinced these all make a difference and I was waiting to be proven wrong,” she says. Wall focused at first on nematodes in deserts and arid croplands, conducting the bulk of her research in southern California, New Mexico and Michigan. By the late 1980s, she was seeking ways to understand a species' impact on an ecosystem. “If you want to find out how a plant parasite has an effect on a root or a predator, how do you exclude everything in the soil except that?” She tried chemicals to kill off species, but they also harmed what she wanted to study. Then a colleague suggested that Wall go somewhere without plants, where the food web was simpler. “I tossed around a number of places,” she says. “And we ended up in Antarctica.” She and her colleague Ross Virginia from Dartmouth College in Hanover, New Hampshire, decided to collect samples in the McMurdo Dry Valleys, a series of ice-free basins near the US McMurdo research station. The valleys receive no snow or rain, and humidity is so low that researchers have found the mummified remains of seals that made their way into the valleys thousands of years ago. Previous researchers had discovered nematodes and other life near glacier-fed streams that trickle during summer, but experts thought that the dry soils making up most of the valleys were barren. On one of Wall and Virginia's first visits to the Dry Valleys, they had just six hours to collect as many samples as possible before the helicopter returned to pick them up. They found nematodes in about 65% of the samples. “I couldn't believe it,” she says. Ultimately, this showed that life can thrive even in the most inhospitable underground environments, revealing that major ecosystems were being overlooked. Wall has returned to the Dry Valleys every field season except 1992, when she didn't receive funding for the trip. To recognize that long-running research, the US Geological Survey named valleys there after Wall and Virginia. Their work in Antarctica dovetailed with discoveries that Wall had previously made about how nematodes cope with extremely dry conditions in the US Southwest. In the Chihuahuan Desert, Wall and her colleagues showed that the worms rely on anhydrobiosis1: they shed most of their water and put metabolic activity on hold. Wall says that the nematodes end up looking like Cheerios, the ring-shaped dry cereal. When she went to Antarctica, Wall and her colleagues found that Dry Valley nematodes use the same mechanism2 to cope with arid conditions there3. With one eye focused on tiny nematodes, Wall kept the other on the bigger picture of how these creatures fit into ecosystems. This was all part of her ever-growing desire to understand and highlight the importance of life underground — something routinely ignored by many researchers until roughly the past decade. Studies that tracked the decomposition of fallen leaves and other organic materials, for example, tended to overlook the role of soil organisms. Wall says she grew tired of that limited perspective. “We wanted to show that animals are important in these processes.” So in 2001, she started a global, multiyear project to measure the impact of soil animals. Her team sent mesh bags filled with hay to colleagues at more than 30 sites around the world. Placed in various locations, the bags attracted worms, beetles and other types of soil invertebrate, while control bags excluded them. Wall's team then analysed the carbon content in each bag and compared the rates at which the organic matter decomposed with and without the soil animals. The results supported Wall's point: soil fauna increased decomposition rates significantly in many regions4. A follow-up study5 found that excluding soil fauna reduced decomposition rates by a global average of 35%. Those studies helped to convince researchers to pay more attention to life in soil (see ‘Soils under siege’). “We now understand how key these organisms are to many ecosystem processes,” says Amy Austin, an ecologist at the University of Buenos Aires. The litter finding means that there could be big changes in how carbon moves throughout ecosystems as forces such as climate change alter soil communities. Wall and her colleagues have seen some of this up close during their most recent field season in Antarctica. In as-yet-unpublished work, they found that the dominant nematode in the Dry Valleys, an endemic genus named Scottnema, has been declining in number, whereas a nematode that lives in wetter soils, Eudorylaimus, has been increasing, thanks to the melting of ice and permafrost. “It looks like there's going to be a species shift,” she says. “It's a fight for habitat.” Scottnema is Wall's favourite nematode. “It's living in this harshest environment, mostly by itself, and it's just so recognizable,” she says. But that's not the only reason that she has concerns about the species' decline. The two nematodes feed on different carbon sources in the soil, and population changes could alter the rate at which underground carbon escapes into the atmosphere. If so, the carbon-storage potential of the soil in Antarctica — a crucial region for absorbing carbon dioxide from the atmosphere — could change. Shifts in soil biota elsewhere on the planet could also affect how much carbon remains locked up, she says. In August this year, Wall found herself at the White House talking about soils with other experts and policymakers as part of a national effort to prevent erosion and promote soil health. It was the latest scene in a role she has increasingly embraced over the past 15 years — to bring soil health to the global stage. As Wall's research career blossomed, she took on more leadership positions. She served as president of the American Institute of Biological Sciences in 1993 and the Ecological Society of America in 1999. By that point, her involvement in these organizations was making her think bigger. “I'd been pretty concentrated on the Antarctic research,” she says. “I thought I should be doing more.” She began participating in and leading initiatives that were increasingly global in scope — chairing, for example, the International Biodiversity Observation Year starting in 2001, which funded research projects to highlight the importance of biodiversity around the world. In 2011, Wall became the founding science chair of the Global Soil Biodiversity Initiative, the group behind the soil atlas that was launched in May. Looking forward, Wall wants to integrate data on soil health and biodiversity into global policies for mitigating large-scale environmental challenges. And she's talking to colleagues about launching a big US experiment to unravel the relationships between soils, biodiversity and health. “Conservation and protecting species is a very old idea, and so is soil conservation. But only now are these two ideas coming together,” she says. While campaigning for soils, Wall has also been a champion for women in science. When she was starting out, there weren't many role models for women in her field. And when she made her first trips to Antarctica, she made do with men's long underwear and boots, and endured eight-hour flights on military aircraft that lacked sit-down toilets. Wall was initially turned down for a tenure-track position at the University of California, Riverside, in the late 1980s — a decision that she and others suggest was related to her gender. Jill Baron, director of the North American Nitrogen Center at Colorado State University, says that how Wall recovered from that rejection is emblematic of her character. “She moved on into this stellar career,” says Baron. “And she's been working to make sure that other young women who come in don't have to ever have that again.” That kind of drive makes a big impression on people just entering science. Ashley Shaw, a PhD student studying under Wall, recalls their first meeting. “She was just so enthusiastic about her science and what she was working on,” says Shaw. “I walked away feeling like I could save the world.” Wall joined Colorado State University in 1993 to become director of the institution's Natural Resource Ecology Laboratory. There, colleagues say, she attracted interdisciplinary, accomplished scientists, which elevated the stature of the lab both on and off campus. She now serves as founding director of the university's School of Global Environmental Sustainability. There, in an office covered in photos and paraphernalia from Antarctica, she talks eagerly about her goals for the future — and takes offence when people ask her if she plans to retire. “Whether I pass my physical to go to Antarctica or get too old and have to have a wheelchair dropped for me from the sky,” she says, “I want to keep working on the issues.”

Lantano B.,University of Buenos Aires | Lantano B.,National University of Luján | Torviso M.R.,University of Buenos Aires | Bonesi S.M.,University of Buenos Aires | And 2 more authors.
Coordination Chemistry Reviews | Year: 2015

Metal-assisted trifluoromethylation and perfluoroalkylation reactions are probably one of the first approaches employed to achieve fluoroalkyl-group substitutions of organic substrates through the use of metals such as copper. Fluoroalkylation reactions of both aromatic and aliphatic substrates involving the employment of perfluoroalkyl halides RfX in conjunction with metallic species, and nucleophilic fluoroalkylating reagents in the presence of metals or organometallic species will be studied. Fluoroalkylation reactions utilizing electrophilic fluoroalkylating reagents in the presence of transition metals or trifluoromethylthiolation reactions will not be the subject of this article. Recently emerging literature (2011-present), with special emphasis on updates from previous review articles on the metal-mediated fluoroalkylation of aromatic substrates will be dealt with. © 2014 Elsevier B.V.

Di L.-J.,U.S. National Cancer Institute | Fernandez A.G.,U.S. National Cancer Institute | De Siervi A.,University of Buenos Aires | Longo D.L.,U.S. National Institute on Aging | Gardner K.,U.S. National Cancer Institute
Nature Structural and Molecular Biology | Year: 2010

Though the linkages between germline mutations of BRCA1 and hereditary breast cancer are well known, recent evidence suggests that altered BRCA1 transcription may also contribute to sporadic forms of breast cancer. Here we show that BRCA1 expression is controlled by a dynamic equilibrium between transcriptional coactivators and co-repressors that govern histone acetylation and DNA accessibility at the BRCA1 promoter. Eviction of the transcriptional co-repressor and metabolic sensor, C terminalgbinding protein (CtBP), has a central role in this regulation. Loss of CtBP from the BRCA1 promoter through estrogen induction, depletion by RNA interference or increased NAD + /NADH ratio leads to HDAC1 dismissal, elevated histone acetylation and increased BRCA1 transcription. The active control of chromatin marks, DNA accessibility and gene expression at the BRCA1 promoter by this 'metabolic switch' provides an important molecular link between caloric intake and tumor suppressor expression in mammary cells. © 2010 Nature America, Inc. All rights reserved.

Ferder M.,University of Buenos Aires | Inserra F.,Austral University | Manucha W.,National University of Cuyo | Ferder L.,Ponce School of Medicine & Health Sciences
American Journal of Physiology - Cell Physiology | Year: 2013

This review attempts to show that there may be a relationship between inflamma-tory processes induced by chronic overstimulation of the renin-angiotensin system (RAS) and the worldwide deficiency of vitamin D (VitD) and that both disorders are probably associated with environmental factors. Low VitD levels represent a risk factor for several apparently different diseases, such as infectious, autoimmune, neu-rodegenerative, and cardiovascular diseases, as well as diabetes, osteoporosis, and cancer. Moreover, VitD insufficiency seems to predispose to hypertension, metabolic syndrome, left ventricular hypertrophy, heart failure, and chronic vascular inflamma-tion. On the other hand, inappropriate stimulation of the RAS has also been associated with the pathogenesis of hypertension, heart attack, stroke, and hypertrophy of the left ventricle and vascular smooth muscle cells. Because VitD receptors (VDRs) and RAS receptors are almost distributed in the same tissues, a possible link between VitD and the RAS is even more plausible. Furthermore, from an evolutionary point of view, both systems were developed simultaneously, actively participating in the regulation of inflammatory and immunological mechanisms. Changes in RAS activity and activation of the VDR seem to be inversely related; thus any changes in one of these systems would have a completely opposite effect on the other, making it possible to speculate that the two systems could have a feedback relationship. In fact, the pandemic of VitD deficiency could be the other face of increased RAS activity, which probably causes lower activity or lower levels of VitD. Finally, from a therapeutic point of view, the combination of RAS blockade and VDR stimulation appears to be more effective than either RAS blockade or VDR stimulation individually. © 2013 the American Physiological Society.

Perazzo C.A.,Favaloro University | Gratton J.,University of Buenos Aires
Physics of Fluids | Year: 2010

With the purpose of modeling the process of mountain building, we investigate the evolution of the ridge produced by the convergent motion of a system consisting of two layers of liquids that differ in density and viscosity to simulate the crust and the upper mantle that form a lithospheric plate. We assume that the motion is driven by basal traction. Assuming isostasy, we derive a nonlinear differential equation for the evolution of the thickness of the crust. We solve this equation numerically to obtain the profile of the range. We find an approximate self-similar solution that describes reasonably well the process and predicts simple scaling laws for the height and width of the range as well as the shape of the transversal profile. We compare the theoretical results with the profiles of real mountain belts and find an excellent agreement. © 2010 American Institute of Physics.

Hamilton C.E.,Mtt Agrifood Research Finland | Gundel P.E.,Mtt Agrifood Research Finland | Gundel P.E.,University of Buenos Aires | Helander M.,University of Turku | Saikkonen K.,Mtt Agrifood Research Finland
Fungal Diversity | Year: 2012

Reactive oxygen species are in all types of organisms from microbes to higher plants and animals. They are by-products of normal metabolism, such as photosynthesis and respiration, and are responsive to abiotic and biotic stress. Accumulating evidence suggests reactive oxygen species play a vital role in programmed cell death, stress responses, plant defense against pathogens and systemic stress signaling in conjunction with antioxidant production. Here, we propose that reactive oxygen species and antioxidants, as both universal and evolutionarily conserved, are likely to play important role(s) in symbiotic interactions. To support this hypothesis we review the root and foliar fungal endophyte literature specific to fungal-plant symbiotum production of reactive oxygen species and antioxidants in response to stress. These asymptomatic fungi can produce antioxidants in response to both biotic and abiotic stress when grown in culture as well as in planta. In addition, there is a growing but nascent literature reporting a significant impact of endophyte colonization on the antioxidant activity of colonized (E+) hosts when compared to uncolonized (E-) hosts, especially when exposed to stress. Here we summarize general patterns emerging from the growing literature specific to antioxidant activity of endophytes in colonized hosts and bring up possible future research questions and approaches. The consequences of changes in reactive oxygen species production and increased antioxidant activity in the symbiotum appear to be beneficial in many instances; but costs are also indicated. Unexplored questions are: 1) to what extent do antioxidants originating from the fungal endophyte mediate host metabolism, and thereby control host responses to endophyte colonization; (2) what role do fungal, plant, or symbiotum produced reactive oxygen species and antioxidants have in determining symbiotic outcome between extremes of pathogenicity and mutualism; and (3) what role if any, do the production of reactive oxygen species and their antioxidant counterparts play in the symbiotum's ability to respond to changing selection pressures? If as the literature suggests, such endophyte imposed mediation can be utilized to foster increases in plant production in resource limited habitats then the utilization of fungal endophytes may prove useful in agronomic and conservation settings. © 2012 The Mushroom Research Foundation.

Pastor V.,University of Buenos Aires | Host L.,University of Strasbourg | Zwiller J.,University of Strasbourg | Bernabeu R.,University of Buenos Aires
Journal of Neurochemistry | Year: 2011

Epigenetic mechanisms have recently been shown to be involved in the long-term effects of drugs of abuse. A well described epigenetic mechanism modulating transcriptional activity consists in the binding to DNA of methyl-CpG binding proteins, such as MeCP2, recruiting histone deacetylases (HDACs). Nicotine causes long-term changes in the brain, but little is known concerning the mechanisms involved in nicotine-preference. Using a nicotine-conditioned place preference protocol, we demonstrate here that the histone deacetylase inhibitor phenylbutyrate was able to dramatically reduce the preference for nicotine, without altering the aversive properties of the drug. We measured immunohistochemically the acetylation of lysine-9 of histone H3, and the expression of phosphorylated cAMP-response element-binding protein, HDAC2 and methyl-CpG-binding protein 2 in the striatum and prefrontal cortex of rats displaying nicotine-preference or aversion and treated with phenylbutyrate. We show that, at the dose administered, the inhibitor was effective in inhibiting HDAC activity. The data suggest that phosphorylated cAMP-response element-binding protein participates in the establishment of conditioned place preference, but not in the reduction of nicotine-preference in response to phenylbutyrate. Moreover, striatal expression of HDAC2 in response to phenylbutyrate mirrored the behavioral effects of the inhibitor, suggesting that HDAC2 is involved in promoting synaptic plasticity underlying the preference for nicotine. © 2011 International Society for Neurochemistry.

Saikkonen K.,Mtt Agrifood Research Finland | Gundel P.E.,Mtt Agrifood Research Finland | Gundel P.E.,University of Buenos Aires | Helander M.,University of Turku
Journal of Chemical Ecology | Year: 2013

Defensive mutualism is widely accepted as providing the best framework for understanding how seed-transmitted, alkaloid producing fungal endophytes of grasses are maintained in many host populations. Here, we first briefly review current knowledge of bioactive alkaloids produced by systemic grass-endophytes. New findings suggest that chemotypic diversity of the endophyte-grass symbiotum is far more complex, involving multifaceted signaling and chemical cross-talk between endophyte and host cells (e.g., reactive oxygen species and antioxidants) or between plants, herbivores, and their natural enemies (e.g., volatile organic compounds, and salicylic acid and jasmonic acid pathways). Accumulating evidence also suggests that the tight relationship between the systemic endophyte and the host grass can lead to the loss of grass traits when the lost functions, such as plant defense to herbivores, are compensated for by an interactive endophytic fungal partner. Furthermore, chemotypic diversity of a symbiotum appears to depend on the endophyte and the host plant life histories, as well as on fungal and plant genotypes, abiotic and biotic environmental conditions, and their interactions. Thus, joint approaches of (bio)chemists, molecular biologists, plant physiologists, evolutionary biologists, and ecologists are urgently needed to fully understand the endophyte-grass symbiosis, its coevolutionary history, and ecological importance. We propose that endophyte-grass symbiosis provides an excellent model to study microbially mediated multirophic interactions from molecular mechanisms to ecology. © 2013 Springer Science+Business Media New York.

Caggiano A.,University of Buenos Aires | Martinelli E.,University of Salerno
Composite Structures | Year: 2013

The present paper deals with the bond behaviour of Fibre Reinforced Polymer (FRP) laminates glued to brittle substrates. Based on a similar proposal already available in the scientific literature for discrete-crack analyses on plain concrete, this work formulates a numerical model completely conceived within the general framework of Fracture Mechanics and plasticity-based concepts. This is the key novel aspect of the proposed work, whereas, as a matter of fact, the most common proposals and theoretical models available in the scientific literature and adopted for describing the bond behaviour of FRP-to-brittle adhesive joints are generally based on assuming "a priori" the analytical expression of the interface bond-slip law. Numerical applications demonstrate the soundness of the proposed formulation and show a very good agreement with experimental results of FRP-to-concrete bond-slip tests. © 2012 Elsevier Ltd.

Martinelli E.,University of Salerno | Koenders E.A.B.,Federal University of Rio de Janeiro | Koenders E.A.B.,Technical University of Delft | Caggiano A.,University of Buenos Aires
Cement and Concrete Composites | Year: 2013

This paper presents a sound theoretical formulation and an effective numerical implementation of a heat-flow and hydration model for concrete hardening. The model is based on the Fourier equation of heat flow with the adiabatic hydration curve employed as a reference for simulating the hydration heat source. The proposed formulations are based on a consistent scheme for the partial differential equation and its boundary and starting conditions. The hydration kinetics is simulated through the Arrhenius approach. Formulations for the compressive strength and the elastic modulus are provided and the maturity function is also considered. A finite difference numerical solution is derived with a forward explicit time integration in the time-space domain. The numerical solution is designed as a stepwise "recipe" specifically conceived to be easily implemented by means of either a high-level programming language or even a spreadsheet tool. Experimental temperature measurements for two different mixtures, under adiabatic and semi-adiabatic conditions, are used for validating the proposed model. The adiabatic and semi-adiabatic temperature simulations show good agreement with the experimental data for both concrete mixtures. The degree of hydration could be simulated and used as the fundamental parameter for scrutinising the evolution of the compressive strength. Particularly, a linear trend between the compressive strength and the degree of hydration and the maturity was figured out. © 2013 Elsevier Ltd. All rights reserved.

D'Alessio C.,University of Buenos Aires | Dahms N.M.,Medical College of Wisconsin
Current Protein and Peptide Science | Year: 2015

N-glycosylation in the endoplasmic reticulum (ER) consists of the transfer of a preassembled glycan conserved among species (Glc3Man9GlcNAc2) from a lipid donor to a consensus sequence within a nascent protein that is entering the ER. The protein-linked glycans are then processed by glycosidases and glycosyltransferases in the ER producing specific structures that serve as signalling molecules for the fate of the folding glycoprotein: to stay in the ER during the folding process, to be retrotranslocated to the cytosol for proteasomal degradation if irreversibly misfolded, or to pursue transit through the secretory pathway as a mature glycoprotein. In the ER, each glycan signalling structure is recognized by a specific lectin. A domain similar to that of the mannose 6-phosphate receptors (MPRs) has been identified in several proteins of the secretory pathway. These include the beta subunit of glucosidase II (GII), a key enzyme in the early processing of the transferred glycan that removes middle and innermost glucoses and is involved in quality control of glycoprotein folding in the ER (QC), the lectins OS-9 and XTP3-B, proteins involved in the delivery of ER misfolded proteins to degradation (ERAD), the gamma subunit of the Golgi GlcNAc-1-phosphotransferase, an enzyme involved in generating the mannose 6-phosphate (M6P) signal for sorting acidic hydrolases to lysosomes, and finally the MPRs that deliver those hydrolytic enzymes to the lysosome. Each of the MRH-containing proteins recognizes a different signalling N-glycan structure. Three-dimensional structures of some of the MRH domains have been solved, providing the basis to understand recognition mechanisms. © 2015 Bentham Science Publishers.

Caggiano A.,University of Buenos Aires | Martinelli E.,University of Salerno | Faella C.,University of Salerno
International Journal of Solids and Structures | Year: 2012

Composite materials, such as fiber reinforced polymers (FRP), are more and more common as strengthening solution for existing structures. Adhesion between FRP and the existing substrate generally represents one of the main concerns on the effectiveness of these techniques. The bond behaviour of composite materials on concrete substrates (but also steel, masonry and wooden ones) are generally investigated by means of pull-out tests. The present paper, starting from the most common assumptions of the mechanical behaviour of the various materials, proposes a fully-analytical formulation for determining the response in terms of the relationship between the external force and the corresponding maximum interface slip observed in those tests. The proposed approach emphasises the key behavioural differences between "short" and "long" bonding length. The former are characterised by a softening behaviour of the relationship between the applied force and the maximum slip, while the latter exhibits a numerically challenging snap-back behaviour. All the key points of the relationship between the external force and the maximum interface slip are defined in closed-form for both the above mentioned cases. Finally, a comparison with some experimental results obtained on FRP-to-concrete pull-out tests are proposed. © 2012 Elsevier Ltd. All rights reserved.

Caggiano A.,University of Buenos Aires | Martinelli E.,University of Salerno
Materials and Design | Year: 2012

This paper presents a unified formulation for simulating the overall bond behaviour of fibres embedded in cementitious matrices. In principle, such a formulation is based on assuming a model between interface bond stresses and the corresponding relative displacements. Two alternative models are actually considered in this paper. The first one is based on a refined fracture-based plasticity model which requires a numerical solution approach; the second one assumes a simplified bilinear relationship and can be handled analytically. Both models, considered in the present formulation, address the behaviour of fibres under tensile axial stresses which result in a " mode II" debonding phenomenon. Finally, numerical results are reported for both validating the proposed models against relevant experimental results and pointing out the differences possibly arising by adopting the two alternative models considered in this paper. © 2012 Elsevier Ltd.

Martinelli E.,University of Salerno | Caggiano A.,University of Buenos Aires
Polymers | Year: 2014

The mechanical behavior of the adhesive interface between the fiber-reinforced polymer (FRP) strip and the concrete substrate often controls the response of FRP-strengthened reinforced concrete (RC) members. Plenty of studies devoted to understanding the mechanical behavior of FRP strips glued to concrete are currently available in the scientific literature. However, they are mainly focused on the response under monotonic actions, which is certainly relevant in a wide class of practical applications. Conversely, few contributions are currently available to better understand the response of FRP-to-concrete interfaces under cyclic actions, such as those deriving from either seismic excitations or traffic loads. This paper presents a unified numerical approach to simulate both monotonic and cyclic behavior of FRP plates glued on quasi-brittle substrates like those made of concrete. Particularly, a damage-based approach is proposed to simulate the fracture behavior of FRP-to-concrete joints under loading/unloading cycling tests. The model is formulated within the general framework of Fracture Mechanics and is based on assuming that fracture at the FRP-to-concrete interface develops in (pure shear) mode II, as widely accepted in similar problems. Two alternative expressions of the bond-slip behavior are herein considered and their preliminary validation is finally proposed. The proposed results highlight the difference between the monotonic and the cyclic response; particularly,they show that the latter is characterized by a significantly lower force and displacement capacity. © 2014 by the authors.

Magarinos M.P.,University of Buenos Aires | Carmona S.J.,University of Buenos Aires | Crowther G.J.,University of Washington | Ralph S.A.,University of Melbourne | And 4 more authors.
Nucleic Acids Research | Year: 2012

The TDR Targets Database (http://tdrtargets.org) has been designed and developed as an online resource to facilitate the rapid identification and prioritization of molecular targets for drug development, focusing on pathogens responsible for neglected human diseases. The database integrates pathogen specific genomic information with functional data (e.g. expression, phylogeny, essentiality) for genes collected from various sources, including literature curation. This information can be browsed and queried using an extensive web interface with functionalities for combining, saving, exporting and sharing the query results. Target genes can be ranked and prioritized using numerical weights assigned to the criteria used for querying. In this report we describe recent updates to the TDR Targets database, including the addition of new genomes (specifically helminths), and integration of chemical structure, property and bioactivity information for biological ligands, drugs and inhibitors and cheminformatic tools for querying and visualizing these chemical data. These changes greatly facilitate exploration of linkages (both known and predicted) between genes and small molecules, yielding insight into whether particular proteins may be druggable, effectively allowing the navigation of chemical space in a genomics context. © The Author(s) 2011. Published by Oxford University Press.

De Cavanagh E.M.V.,Austral University | Inserra F.,University of Buenos Aires | Ferder L.,Ponce School of Medicine & Health Sciences
Cardiovascular Research | Year: 2011

Protein and lipid oxidationmainly by mitochondrial reactive oxygen species (mtROS)was proposed as a crucial determinant of health and lifespan. Angiotensin II (Ang II) enhances ROS production by activating NAD(P)H oxidase and uncoupling endothelial nitric oxide synthase (NOS). Ang II also stimulates mtROS production, which depresses mitochondrial energy metabolism. In rodents, reninangiotensin system blockade (RAS blockade) increases survival and prevents age-associated changes. RAS blockade reduces mtROS and enhances mitochondrial content and function. This suggests that Ang II contributes to the ageing process by prompting mitochondrial dysfunction. Since Ang II is a pleiotropic peptide, the age-protecting effects of RAS blockade are expected to involve a variety of other mechanisms. Caloric restriction (CR)an age-retarding intervention in humans and animalsand RAS blockade display a number of converging effects, i.e. they delay the manifestations of hypertension, diabetes, nephropathy, cardiovascular disease, and cancer; increase body temperature; reduce body weight, plasma glucose, insulin, and insulin-like growth factor-1; ameliorate insulin sensitivity; lower protein, lipid, and DNA oxidation, and mitochondrial H2O2 production; and increase uncoupling protein-2 and sirtuin expression. A number of these overlapping effects involve changes in mitochondrial function. In CR, peroxisome proliferator-activated receptors (PPARs) seem to contribute to age-retardation partly by regulating mitochondrial function. RAS inhibition up-regulates PPARs; therefore, it is feasible that PPAR modulation is pivotal for mitochondrial protection by RAS blockade during rodent ageing. Other potential mechanisms that may underlie RAS blockades mitochondrial benefits are TGF-β down-regulation and up-regulation of Klotho and sirtuins. In conclusion, the available data suggest that RAS blockade deserves further research efforts to establish its role as a potential tool to mitigate the growing problem of age-associated chronic disease. © 2010 The Author.

Urtreger A.J.,University of Buenos Aires | Kazanietz M.G.,University of Pennsylvania | Bal De Kier Joffe E.D.,University of Buenos Aires
IUBMB Life | Year: 2012

The protein kinase C (PKC) family of serine/threonine kinases has been intensively studied in cancer since their discovery as major receptors for the tumor-promoting phorbol esters. The contribution of each individual PKC isozyme to malignant transformation is only partially understood, but it is clear that each PKC plays different role in cancer progression. PKC deregulation is a common phenomenon observed in breast cancer, and PKC expression and localization are usually dynamically regulated during mammary gland differentiation and involution. In fact, the overexpression of several PKCs has been reported in malignant human breast tissue and breast cancer cell lines. In this review, we summarize the knowledge available on the specific roles of PKC isoforms in the development, progression, and metastatic dissemination of mammary cancer. We also discuss the role of PKC isoforms as therapeutic targets, and their potential as markers for prognosis or treatment response. © 2011 IUBMB.

Doherty K.M.,University College London | van de Warrenburg B.P.,Radboud University Nijmegen | Peralta M.C.,Cesar Milstein Hospital | Silveira-Moriyama L.,University College London | And 3 more authors.
The Lancet Neurology | Year: 2011

Postural deformities are frequent and disabling complications of Parkinson's disease (PD) and atypical parkinsonism. These deformities include camptocormia, antecollis, Pisa syndrome, and scoliosis. Recognition of specific postural syndromes might have differential diagnostic value in patients presenting with parkinsonism. The evidence to date suggests that postural deformities have a multifactorial pathophysiology. Contributing factors include muscular rigidity; axial dystonia; weakness caused by myopathy; body scheme defects due to centrally impaired proprioception; and structural changes in the spine. The relative contribution of these different factors varies between patients and across specific syndromes. Improved understanding of the mechanisms underlying postural deformities in PD might ultimately lead us to more effective management strategies for these disabling and drug-refractory complications. © 2011 Elsevier Ltd.

Jenik M.,University of Buenos Aires | Parra R.G.,University of Buenos Aires | Radusky L.G.,University of Buenos Aires | Turjanski A.,University of Buenos Aires | And 2 more authors.
Nucleic Acids Research | Year: 2012

The frustratometer is an energy landscape theory-inspired algorithm that aims at quantifying the location of frustration manifested in protein molecules. Frustration is a useful concept for gaining insight to the proteins biological behavior by analyzing how the energy is distributed in protein structures and how mutations or conformational changes shift the energetics. Sites of high local frustration often indicate biologically important regions involved in binding or allostery. In contrast, minimally frustrated linkages comprise a stable folding core of the molecule that is conserved in conformational changes. Here, we describe the implementation of these ideas in a webserver freely available at the National EMBNet node-Argentina, at URL: http://lfp.qb.fcen.uba. ar/embnet/. © 2012 The Author(s).

Fowlkes J.D.,Oak Ridge National Laboratory | Kondic L.,New Jersey Institute of Technology | Diez J.,University of Buenos Aires | Wu Y.,University of Tennessee at Knoxville | And 2 more authors.
Nano Letters | Year: 2011

A nanoscale, synthetic perturbation was all that was required to nudge a natural, self-assembly process toward significantly higher order. Metallic thin film strips were transformed into nanoparticle arrays by nanosecond, liquid-phase dewetting. Arrays formed according to an evolving Rayleigh - Plateau instability, yet nanoparticle diameter and pitch were poorly controlled. However, by patterning a nanoscale sinusoid onto the original strip edge, a precise nanoparticle diameter and pitch emerged superseding the naturally evolving Rayleigh - Plateau instability. © 2011 American Chemical Society.

Apesteguia S.,Maimónides University | Gomez R.O.,University of Buenos Aires | Rougier G.W.,University of Louisville
Zoological Journal of the Linnean Society | Year: 2012

Herein we describe a new rhynchocephalian taxon from the Middle Jurassic of Patagonia, Argentina, representing the first Jurassic record of the group in South America. The new taxon, consisting of a complete dentary, is ascribed to Sphenodontia based on the presence of a deep and wide Meckelian groove, long posterior process, well-developed coronoid process, and acrodont teeth showing dental regionalization including successional, alternate hatchling, and additional series. This allocation is reinforced by a phylogenetic analysis that places the new taxon in a basal position within a clade of sphenodontians that excludes Diphydontosaurus and Planocephalosaurus. Additionally, the new taxon clusters within a Gondwanan clade with the Indian Godavarisaurus from the Jurassic Kota Formation, sharing the presence of recurved and relatively large posterior successional teeth that are ribbed and bear a peculiar anterolingual groove. This sister-group relationship is intriguing from a palaeobiogeographical viewpoint, as it suggests some degree of endemism during the initial stages of the breakup of Pangaea. We also discuss the ontogenetic stage of the new taxon and provide insights on the evolution of successional dentition in rhynchocephalians. © 2012 The Linnean Society of London.

Cardinali D.P.,Pontifical Catholic University of Argentina | Cardinali D.P.,University of Buenos Aires | Furio A.M.,University of Buenos Aires | Brusco L.I.,University of Buenos Aires
Current Neuropharmacology | Year: 2010

Melatonin secretion decreases in Alzheimer's disease (AD) and this decrease has been postulated as responsible for the circadian disorganization, decrease in sleep efficiency and impaired cognitive function seen in those patients. Half of severely ill AD patients develop chronobiological day-night rhythm disturbances like an agitated behavior during the evening hours (so-called "sundowning"). Melatonin replacement has been shown effective to treat sundowning and other sleep wake disorders in AD patients. The antioxidant, mitochondrial and antiamyloidogenic effects of melatonin indicate its potentiality to interfere with the onset of the disease. This is of particularly importance in mild cognitive impairment (MCI), an etiologically heterogeneous syndrome that precedes dementia. The aim of this manuscript was to assess published evidence of the efficacy of melatonin to treat AD and MCI patients. PubMed was searched using Entrez for articles including clinical trials and published up to 15 January 2010. Search terms were "Alzheimer" and "melatonin". Full publications were obtained and references were checked for additional material where appropriate. Only clinical studies with empirical treatment data were reviewed. The analysis of published evidence made it possible to postulate melatonin as a useful ad-on therapeutic tool in MCI. In the case of AD, larger randomized controlled trials are necessary to yield evidence of effectiveness (i.e. clinical and subjective relevance) before melatonin's use can be advocated. © 2010 Bentham Science Publishers Ltd.

Silber A.M.,University of Sao Paulo | Pereira C.A.,University of Buenos Aires
Journal of Membrane Biology | Year: 2012

Protozoan parasites cause thousands of deaths each year in developing countries. The genome projects of these parasites opened a new era in the identification of therapeutic targets. However, the putative function could be predicted for fewer than half of the protein-coding genes. In this work, all Trypanosoma cruzi proteins containing predicted transmembrane spans were processed through an automated computational routine and further analyzed in order to assign the most probable function. The analysis consisted of dissecting the whole predicted protein in different regions. More than 5,000 sequences were processed, and the predicted biological functions were grouped into 19 categories according to the hits obtained after analysis. One focus of interest, due to the scarce information available on trypanosomatids, is the proteins involved in signal-transduction processes. In the present work, we identified 54 proteins belonging to this group, which were individually analyzed. The results show that by means of a simple pipeline it was possible to attribute probable functions to sequences annotated as coding for "hypothetical proteins." Also, we successfully identified the majority of candidates participating in the signal-transduction pathways in T. cruzi. © 2012 Springer Science+Business Media, LLC.

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.

El-Oirdi M.,Université de Sherbrooke | El-Rahman T.A.,Université de Sherbrooke | Rigano L.,Institute Ciencia Y Tecnologia Dr Cesar Milstein | El-Hadrami A.,University of Manitoba | And 4 more authors.
Plant Cell | Year: 2011

Plants have evolved sophisticated mechanisms to sense and respond to pathogen attacks. Resistance against necrotrophic pathogens generally requires the activation of the jasmonic acid (JA) signaling pathway, whereas the salicylic acid (SA) signaling pathway is mainly activated against biotrophic pathogens. SA can antagonize JA signaling and vice versa. Here, we report that the necrotrophic pathogen Botrytis cinerea exploits this antagonism as a strategy to cause disease development. We show that B. cinerea produces an exopolysaccharide, which acts as an elicitor of the SA pathway. In turn, the SA pathway antagonizes the JA signaling pathway, thereby allowing the fungus to develop its disease in tomato (Solanum lycopersicum). SA-promoted disease development occurs through Nonexpressed Pathogen Related1. We also show that the JA signaling pathway required for tomato resistance against B. cinerea is mediated by the systemin elicitor. These data highlight a new strategy used by B. cinerea to overcome the plant's defense system and to spread within the host. © 2011 American Society of Plant Biologists. All rights reserved.

Mastaglia S.R.,University of Buenos Aires | Watman N.P.,Hospital General Of Agudos J M Ramos Mejia | Oliveri B.,University of Buenos Aires
Osteoporosis International | Year: 2010

Introduction: Type 1 Gaucher's disease (GD1) is a lysosomal storage disorder associated with disabling bone involvement. The choice treatment for Gaucher's disease is enzyme replacement therapy (ERT). The use of bisphosphonate treatment for osteopenia and osteoporosis has been suggested. Case: A 22-year-old woman diagnosed with GD1 had received ERT intermittently, depending on availability of the enzyme since the enzyme was not always available. Due to severe bone involvement and multiple vertebral fractures, intravenous administration of 60 mg of pamidronate every 3 months and safe contraception were indicated. Fifteen days after receiving the fourth infusion, the patient informed us she was pregnant. A baby girl was born by cesarean delivery at week 37, showing no evidence of skeletal abnormality or clinical signs of hypocalcemia. The baby developed normally, presenting no significant pathology. At present (age 15 months), height, body weight, and bone mineral density by DXA are within normal range. The mother showed stable total skeleton and right femoral neck bone mineral density (BMD) values, no new fractures, and only ~3% decrease in lumbar spine BMD 15 months post-delivery and after a 1 year breastfeeding period (expected average ~7-8%). Conclusion: It could be posited that pamidronate exerted a positive protective effect on the mother's skeleton with no evidence of adverse effects on pregnancy or on the baby's health to date. © 2009 International Osteoporosis Foundation and National Osteoporosis Foundation.

Perez-Lloret S.,Raul Carrea Institute for Neurological Research | Perez-Lloret S.,University of Buenos Aires | Merello M.,Raul Carrea Institute for Neurological Research
Expert Opinion on Pharmacotherapy | Year: 2014

Introduction: Adenosine A2A receptors are localized in the brain, mainly within the caudate and putamen nuclei of the basal ganglia. Their activation leads to stimulation of the 'indirect' pathway. Conversely, administration of A2A receptor antagonists leads to inhibition of this pathway, which was translated into reduced hypomotility in several animal models of parkinsonism. Areas covered: In this review, the effects of two A2A receptor antagonists, istradefylline and tozadenant, on parkinsonian symptoms in animal and humans will be discussed. Expert opinion: Animal studies have shown potent antiparkinsonian effects for several A2A receptor antagonists, including istradefylline. In clinical trials, istradefylline reduced OFF time when administered with levodopa, but results are inconclusive. Results with tozadenant are scarce. Modification of thalamic blood flow compatible with reduced inhibition was noted in one small trial, followed by a significant reduction in OFF time in a larger one. Therefore, both drugs show promising efficacy for the reduction of OFF time in levodopa-treated Parkinson's disease patients, but further research is needed in order to obtain definitive conclusions. © 2014 Informa UK, Ltd.

Mesz B.,Laboratory of Musical Research and Production LIPM | Sigman M.,University of Buenos Aires | Trevisan M.,University of Buenos Aires
Frontiers in Human Neuroscience | Year: 2012

While there is broad consensus about the structural similarities between language and music, comparably less attention has been devoted to semantic correspondences between these two ubiquitous manifestations of human culture. We have investigated the relations between music and a narrow and bounded domain of semantics: the words and concepts referring to taste sensations. In a recent work, we found that taste words were consistently mapped to musical parameters. Bitter is associated with low-pitched and continuous music (legato), salty is characterized by silences between notes (staccato), sour is high pitched, dissonant and fast and sweet is consonant, slow and soft (Mesz2011). Here we extended these ideas, in a synergistic dialog between music and science, investigating whether music can be algorithmically generated from taste-words. We developed and implemented an algorithm that exploits a large corpus of classic and popular songs. New musical pieces were produced by choosing fragments from the corpus and modifying them to minimize their distance to the region in musical space that characterizes each taste. In order to test the capability of the produced music to elicit significant associations with the different tastes, musical pieces were produced and judged by a group of non musicians. Results showed that participants could decode well above chance the taste-word of the composition. We also discuss how our findings can be expressed in a performance bridging music and cognitive science. © 2012 Mesz, Sigman and Trevisan.

Garbulsky M.F.,Autonomous University of Barcelona | Garbulsky M.F.,University of Buenos Aires | Penuelas J.,Autonomous University of Barcelona | Gamon J.,University of Alberta | And 2 more authors.
Remote Sensing of Environment | Year: 2011

Traditional remote sensing techniques allow the assessment of green plant biomass, and therefore plant photosynthetic capacity. However, detecting how much of this capacity is actually realized is a more challenging goal. Is it possible to remotely assess actual carbon fluxes? Can this be done at leaf, canopy and ecosystem scales and at different temporal scales? Different approaches can be used to answer these questions. Among them, the Photochemical Reflectance Index (PRI) derived from narrow-band spectroradiometers is a spectral index increasingly being used as an indicator of photosynthetic efficiency. We examined and synthesized the scientific literature on the relationships between PRI and several ecophysiological variables across a range of plant functional types and ecosystems at the leaf, canopy and ecosystem levels and at the daily and seasonal time scales. Our analysis shows that although the strength of these relationships varied across vegetation types, levels of organization and temporal scales, in most reviewed articles PRI was a good predictor of photosynthetic efficiency or related variables with performances at least as good as the widely used NDVI as indicator of green biomass. There are possible confounding factors related to the intensity of the physiological processes linked to the PRI signals, to the structure of the canopies and to the illumination and viewing angles that warrant further studies, and it is expected that the utility of PRI will vary with the ecosystem in question due to contrasting environmental constraints, evolutionary strategies, and radiation use efficiency (RUE; the ratio between carbon uptake and light absorbed by vegetation) variability. Clearly, more research comparing ecosystem responses is warranted. Additionally, like any 2-band index that is affected by multiple factors, the interpretation of PRI can be readily confounded by multiple environmental variables, and further work is needed to understand and constrain these effects. Despite these limitations, this review shows an emerging consistency of the RUE-PRI relationship that suggests a surprising degree of functional convergence of biochemical, physiological and structural components affecting leaf, canopy and ecosystem carbon uptake efficiencies. PRI accounted for 42%, 59% and 62% of the variability of RUE at the leaf, canopy and ecosystem respective levels in unique exponential relationships for all the vegetation types studied. It seems thus that by complementing the estimations of the fraction of photosynthetically active radiation intercepted by the vegetation (FPAR), estimated with NDVI-like indices, PRI enables improved assessment of carbon fluxes in leaves, canopies and many of the ecosystems of the world from ground, airborne and satellite sensors. © 2010 Elsevier Inc.

Rapalini A.E.,University of Buenos Aires | Trindade R.I.,University of Sao Paulo | Poire D.G.,National University of La Plata
Precambrian Research | Year: 2013

The Late Ediacaran to Cambrian Sierras Bayas Group (Villa Mónica, Cerro Largo, Olavarría and Loma Negra Formations) and the Cerro Negro Formation, exposed along the Tandilia system in the province of Buenos Aires (Argentina) were revisited and studied paleomagnetically. Our results supersede those of Valencio et al. (1980) for the La Tinta Formation (old stratigraphic name of these units). Three hundred and twenty-eight samples were collected from forty-four sites in gently folded to subhorizontal strata distributed along the whole stratigraphic succession. Detailed paleomagnetic study comprised systematic stepwise demagnetization by both AF and thermal methods, the latter being generally the most effective in isolating the characteristic remanence. Different magnetic components were defined from different units of the succession. Besides a recent, probably viscous, secondary component (component A), the most widespread magnetic remanence (component B) is a dual-polarity post-tectonic secondary remanence. This component, carried by both hematite and magnetite, corresponds to that originally determined by Valencio et al. (1980) and previously interpreted as primary. This component found in all carbonatic rocks of Villa Mónica and Loma Negra Formations as well as in several claystones and siltstones of the Olavarría Formation do not pass conglomerate and regional tilt tests. The mean in situ direction of component B is Dec: 359.8°, Inc: -63.3°, n: 85 samples, k: 24, α95: 3.2° and yields a paleomagnetic pole virtually identical to the previous one of Valencio and colleagues. It also matches those recently determined from secondary magnetizations in carbonatic and clastic Ediacaran units exposed in Uruguay. The pole positions suggest a Late Permian-Triassic age as the more likely for the acquisition of component B and reveal the presence of a widespread remagnetization event that affected very large areas of the Rio de la Plata craton. Despite this widespread event, some clastic units (claystones, marls) apparently escaped remagnetization. A pre-tectonic, dual polarity, mean remanence (Dec: 28.7°, Inc: 56.1°, n: 17 samples, k: 15, α95: 9.5°) was isolated from the latest Ediacaran-Early Cambrian Cerro Negro Formation (component C). In addition, the Ediacaran Olavarria Formation recorded another apparently ancient remanence, although no field test is available. Its direction (component D) is at Dec: 350.9°, Inc: 47.3°, n: 13 samples, k: 37, α95: 7.0°. Siltstones and claystones of the Ediacaran Cerro Largo Formation were carriers of a characteristic remanence (component E) that shows a better directional grouping after bedding correction, although the field test is not statistically significant, and yield a mean corrected direction at: Dec: 73.7°, Inc: -36.6°, n: 11 samples, k: 15, α95: 12.1°. Finally, a purple horizon of marls on top of the Villa Mónica Formation associated with weathering processes before deposition of the Colombo diamictite, was carrier of a characteristic remanence that attained a better grouping after bedding correction, but again with no statistical significance. This direction (component F) was at Dec: 43.4°, Inc: -36.3°, n: 7 samples, k: 45, α95: 9.1°. Components C-F are interpreted as ancient magnetizations associated either to post-depositional or early to late diagenesis. Mean geomagnetic poles computed from these components fall on the apparent polar wander path for the Rio de la Plata craton from around 600 to 520. Ma, in a correct stratigraphic order and with ages consistent with the most likely ages (or slightly younger) of the different sampled units. These results confirm the already proposed Ediacaran to Cambrian APWP for the Rio de la Plata craton, indicating that it remained at intermediate to low latitudes during most of the Ediacaran. Comparison with coeval paleomagnetic poles from other cratons indicate that by 575. Ma the Rio de la Plata and Congo-Sao Francisco cratons were likely a single plate. It also strongly argues against the generally accepted model that the Rio de la Plata craton was part of the conjugate margin of Eastern Laurentia during the final stages of Rodinia break-up at around 580. Ma. © 2012 Elsevier B.V.

Cuadros-Melgar B.,National Technical University of Athens | De Oliveira J.,University of Buenos Aires | Pellicer C.E.,University of Sao Paulo
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2012

In this work, we probe the stability of a z=3 three-dimensional Lifshitz black hole by using scalar and spinorial perturbations. We found an analytical expression for the quasinormal frequencies of the scalar probe field, which perfectly agree with the behavior of the quasinormal modes obtained numerically. The results for the numerical analysis of the spinorial perturbations reinforce the conclusion of the scalar analysis, i.e., the model is stable under scalar and spinor perturbations. As an application we found the area spectrum of the Lifshitz black hole, which turns out to be equally spaced. © 2012 American Physical Society.

Vera E.I.,Museo Argentino de Ciencias Naturales Bernardino Rivadavia | Vera E.I.,University of Buenos Aires
Cretaceous Research | Year: 2013

A new genus and species of cyathealean fern, Yavanna chimaerica gen. et sp. nov., is erected for several permineralized stems recovered from the Early Cretaceous (Aptian) Cerro Negro Formation, which crops out at the South Shetland Islands, Antarctica. The new species is characterized by solenostelic erect stems with medullary bundles traversing the pith, and surrounded by persistent petiole bases and adventitious roots. Proximal petiole bases present a one-parted modified omega-shaped trace, which becomes three-parted distally. The anatomy of the new fern show similarities with both Thyrsopteris elegans Kunze and with the Cyatheaceae s.s., suggesting that it is a representative of an extinct lineage among the Cyatheales. © 2013 Elsevier Ltd.

Helguera P.,University of California at Irvine | Helguera P.,National University of Cordoba | Seiglie J.,University of California at Irvine | Rodriguez J.,University of California at Los Angeles | And 3 more authors.
Cell Metabolism | Year: 2013

Mitochondrial dysfunction and oxidative stress are common features of Down syndrome (DS). However, the underlying mechanisms are not known. We investigated the relationship between abnormal energy metabolism and oxidative stress with transcriptional and functional changes in DS cells. Impaired mitochondrial activity correlated with altered mitochondrial morphology. Increasing fusion capacity prevented morphological but not functional alterations in DS mitochondria. Sustained stimulation restored mitochondrial functional parameters but increased reactive oxygen species production and cell damage, suggesting that reduced DS mitochondrial activity is an adaptive response for avoiding injury and preserving basic cellular functions. Network analysis of genes overexpressed in DS cells demonstrated functional integration in pathways involved in energy metabolism and oxidative stress. Thus, although preventing extensive oxidative damage, mitochondrial downregulation may contribute to increased susceptibility of individuals with DS to clinical conditions in which altered energy metabolism may play a role, such as Alzheimer's disease, diabetes, and some types of autistic spectrum disorders. © 2013 Elsevier Inc.

Lynch J.P.,Critical Care Medicine | Fishbein M.,University of California at Los Angeles | Echavarria M.,University of Buenos Aires
Seminars in Respiratory and Critical Care Medicine | Year: 2011

Adenoviruses (AdV) are DNA viruses that typically cause mild infections involving the upper or lower respiratory tract, gastrointestinal (GI) tract, or conjunctiva. Rare manifestations of AdV infections include hemorrhagic cystitis, hepatitis, hemorrhagic colitis, pancreatitis, nephritis, or encephalitis. Adenovirus infections are more common in young children, owing to lack of humoral immunity. Epidemics of AdV infections may occur in healthy children or adults in closed or crowded settings (particularly military recruits). The disease is more severe, and dissemination is more likely in patients with impaired immunity (eg, organ transplant recipients, human immunodeficiency virus infection, congenital immunodeficiency syndromes). Fatality rates for untreated severe AdV pneumonia or disseminated disease may exceed 50%. More than 50 serotypes of AdV have been identified. Different serotypes display different tissue trophisms and correlate with clinical manifestations of infection. The predominant serotypes differ among countries or regions and change over time. Transmission of novel strains between countries or across continents and replacement of dominant serotypes by new strains may occur. Treatment of AdV infections is controversial because prospective, randomized therapeutic trials have not been done. Cidofovir is considered the drug of choice for severe AdV infections, but not all patients require treatment. Vaccines have been shown to be highly efficacious in reducing the risk of respiratory AdV infection but are currently not available. Copyright © 2011 by Thieme Medical Publishers, Inc.

Centanin L.,University of Heidelberg | Gorr T.A.,Institute of Veterinary Physiology | Wappner P.,University of Buenos Aires
Journal of Insect Physiology | Year: 2010

The insect tracheal system is a continuous tubular network that ramifies into progressively thinner branches to provide air directly to every organ and tissue throughout the body. During embryogenesis the basic architecture of the tracheal system develops in a stereotypical and genetically controlled manner. Later, in larval stages, the tracheal system becomes plastic, and adapts to particular oxygen needs of the different tissues of the body. Oxygen sensing is mediated by specific prolyl-4-hydroxylases that regulate protein stability of the alpha subunit of oxygen-responsive transcription factors from the HIF family. Tracheal cells are exquisitely sensitive to oxygen levels, modulating the expression of hypoxia-inducible proteins that mediate sprouting of tracheal branches in direction to oxygen-deprived tissues. © 2009 Elsevier Ltd. All rights reserved.

Hermsen E.J.,Cornell University | Gandolfo M.A.,Cornell University | Del Carmen Zamaloa M.,University of Buenos Aires
American Journal of Botany | Year: 2012

Premise of the study: Herein, we name, describe, and illustrate new macrofossil material representing Eucalyptus (Myrtaceae: Myrtoideae, Eucalypteae) from the diverse early Eocene Laguna del Hunco (LH) fl ora of Chubut Province, Patagonia, Argentina. We explore the signifi cance of these fossils in light of understanding the fossil record of eucalypts and the biogeography of the Eucalypteae. Methods: Fossils representing vegetative and reproductive organs were collected from multiple LH localities over several field seasons. These specimens were prepared, photographed, and compared to extant Eucalyptus. Additional historical collections of Patagonian fossil Eucalyptus were also examined. Key results: Vegetative and reproductive organs representing five different Eucalyptus taxa were identifi ed in the LH paleoflora. One new taxon each representing leaves, flower buds, and infructescences with co-occurring, isolated capsules are described and named as new Eucalyptus species. Additionally, two flower types cf. Eucalyptus, represented by one specimen each, are illustrated and briefl y described. The fossil species have unique characteristics that independently suggest each belongs within the Eucalypteae. The reproductive material is most similar morphologically to extant Eucalyptus, although it also shares many similarities to the closely related genus Corymbia. Conclusions: The LH fossil Eucalyptus material is among the few eucalypt macrofossils that have recently been named and described and are the oldest macrofossils that can presently be definitively ascribed to the Eucalypteae. They also represent the only credible description of Eucalyptus fossils occurring outside of Australasia and suggest a once broader geographic distribution for this group. © 2012 Botanical Society of America.

Taminiau T.H.,ICFO - Institute of Photonic Sciences | Stefani F.D.,University of Buenos Aires | Van Hulst N.F.,ICFO - Institute of Photonic Sciences | Van Hulst N.F.,Catalan Institution for Research and Advanced Studies
Nano Letters | Year: 2011

Optical antennas link objects to light. Here we derive an analytical model for the interaction of dipolar transitions with radiation through nanorod antenna modes, by modeling nanorods as cavities. The model includes radiation damping, accurately describes the complete emission process, and is summarized in a phase-matching equation. We analytically discuss the quantitative evolution of antenna modes, in particular the gradual emergence of subradiant, super-radiant, and dark modes, as antennas become increasingly more bound, i.e., plasmonic. Our description is valid for the interaction of nanorods with light in general and is thus widely applicable. © 2011 American Chemical Society.

Vera E.I.,Museo Argentino de Ciencias Naturales Bernardino Rivadavia | Vera E.I.,University of Buenos Aires
Alcheringa | Year: 2012

A new species of the osmundalean fossil morphogenus Millerocaulis Tidwell emend. Vera, Millerocaulis tekelili sp. nov. is defined, based on several permineralized stems recovered from exposures of the Lower Cretaceous Cerro Negro Formation on Livingston Island, South Shetland Islands, Antarctica. This new species is characterized by the presence of an ectophloic-dictyoxylic siphonostele, inner parenchymatic and outer sclerotic cortices, heterogeneous sclerotic ring in the petiole bases, absence of sclerenchyma associated with the petiolar xylem trace, petiolar inner cortex with sclerenchyma strands and stipular wings having a large sclerenchyma bundle and several smaller ones. The presence of non-homogeneous sclerotic rings in the petiole bases allows this new species to be clearly distinguished from other Antarctic Millerocaulis, and suggests that it may represent an intermediate form in the evolutionary lineage leading from Millerocaulis to subgenus Claytosmunda of Osmunda. © 2012 Copyright Taylor and Francis Group, LLC.

Piloni N.E.,University of Buenos Aires | Fermandez V.,University of Chile | Videla L.A.,University of Chile | Puntarulo S.,University of Buenos Aires
Toxicology | Year: 2013

An in vivo model in rat was developed by intraperitoneally administration of Fe-dextran to study oxidative stress triggered by Fe-overload in rat brain. Total Fe levels, as well as the labile iron pool (LIP) concentration, in brain from rats subjected to Fe-overload were markedly increased over control values, 6h after Fe administration. In this in vivo Fe overload model, the ascorbyl (A)/ascorbate (AH-) ratio, taken as oxidative stress index, was assessed. The A/AH- ratio in brain was significantly higher in Fe-dextran group, in relation to values in control rats. Brain lipid peroxidation indexes, thiobarbituric acid reactive substances (TBARS) generation rate and lipid radical (LR) content detected by Electron Paramagnetic Resonance (EPR), in Fe-dextran supplemented rats were similar to control values. However, values of nuclear factor-kappaB deoxyribonucleic acid (NFκB DNA) binding activity were significantly increased (30%) after 8h of Fe administration, and catalase (CAT) activity was significantly enhanced (62%) 21h after Fe administration. Significant enhancements in Fe content in cortex (2.4 fold), hippocampus (1.6 fold) and striatum (2.9 fold), were found at 6h after Fe administration. CAT activity was significantly increased after 8h of Fe administration in cortex, hippocampus and striatum (1.4 fold, 86, and 47%, respectively). Fe response in the whole brain seems to lead to enhanced NF-κB DNA binding activity, which may contribute to limit oxygen reactive species-dependent damage by effects on the antioxidant enzyme CAT activity. Moreover, data shown here clearly indicate that even though Fe increased in several isolated brain areas, this parameter was more drastically enhanced in striatum than in cortex and hippocampus. However, comparison among the net increase in LR generation rate, in different brain areas, showed enhancements in cortex lipid peroxidation, without changes in striatum and hippocampus LR generation rate after 6h of Fe overload. This information has potential clinical relevance, as it could be the key to understand specific brain damage occurring in conditions of Fe overload. © 2013 Elsevier Ireland Ltd.

Menegassi B.,University of Sao Paulo | Pilosof A.M.R.,University of Buenos Aires | Areas J.A.G.,University of Sao Paulo
LWT - Food Science and Technology | Year: 2011

The aim of this study was to compare some of the properties of native and extruded amaranth flour obtained under mild and severe extrusion conditions. The chemical composition of the flours was similar. Flours obtained by both extrusion processes presented high solubility in water, low values of L* (luminosity) and an absence of endothermic peak on the DSC method. Water absorption, retrogradation tendency, final viscosity and the viscous behavior by rheology analysis were also studied. The results indicate that extruded flours have a good potential as an ingredient for food exposed to heat treatment at a high temperature and mechanical shear, for use in instant meal products. On the other hand, original flour properties are comparable to those of amaranth starch, which exhibits similarly high quality paste stability, low solubility in water, and elastic behavior, and could be used as a substitute for raw flour in a range of food formulas. © 2011 Elsevier Ltd.

Forastiero R.,University of Buenos Aires | Martinuzzo M.,Italian Hospital
Expert Review of Clinical Immunology | Year: 2015

Antiphospholipid syndrome (APS) is an autoimmune disorder characterized by clinical symptoms of vascular thrombosis and/or pregnancy morbidity in the presence of autoimmune antiphospholipid antibodies (aPL). Current laboratory APS criteria include the presence of at least one of the three relevant aPL: lupus anticoagulant, anticardiolipin antibodies and anti-β2 glycoprotein I antibodies. Therefore, patients could have a single aPL pattern or combinations of aPL. Evidence arising from clinical experience indicates that patients having the highest aPL titer and simultaneous aPL detected by different tests have a worse prognosis and a higher probability of recurrence of the APS clinical features. In recent years, an emerging role of multiple aPL positivity in the identification of high-risk patients with aPL/APS is evident. This paper will review the current knowledge on the clinical relevance of having single or multiple aPL positivity. © 2015 Taylor & Francis.

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

Agency: European Commission | Branch: FP7 | Program: CSA | Phase: ICT-2011.3.4 | Award Amount: 466.09K | Year: 2011

The RISC project aims at deepening strategic R&D cooperation between Europe (EU) and Latin America (LA) in the field of High Performance Computing (HPC) by building a multinational and multi-stakeholder community that will involve a significant representation of the relevant HPC R&D EU and LA actors (researchers, policy makers, users). RISC will identify common needs, research issues and opportunities for cooperative R&D on HPC between EU and LA in the transition to multi-core architectures across the computing spectrum and relevant programming paradigms, algorithms and modelling approaches, thus setting the basis for the formulation of a global strategy for future research. The project will achieve its overall aim via a range of activities: 1. Assessing the ICT collaboration potential in the High Performance Computing and Computational Science area for the two regions; producing a Green Paper on High Performance Computing Drivers and Needs in Latin America; mapping the LA HPC actors and trends; identifying the opportunities for LA ICT actors in the EU and for EU HPC actors in LA; aligning EU and LA HPC policies and strategies; 2. Sharing and disseminating information and results in the focus area of EU HPC to a number of research, policy and practice actors dealing with technology applications in the LA region; making available existing Latin American HPC research to EU research, policy and practice actors;\n3.\tOrganising awareness-raising events about the ECs ICT R&D programmes, in particular those ones relevant to HPC and exascale computing for LA HPC actors. Organising Summer Schools and Advanced Workshops between EU and LA ICT actors to inform and initiate research collaborations between them. Networking, capacity building and training components of these events will enhance the impact 4. Actively engaging the relevant industry by focusing on industrial problems and problems with impact for the society. Providing advanced support services to a selected number of competent Latin American ICT actors to build long-term relationships with key EU counterparts. The target areas are: Innovation and HPC and its impact, Mathematical Models enhancing HPC and key areas such as Life Sciences, Climate Change, Financial Modelling etc with the corresponding research clusters concentrated around these areas.\n5.\tExtending HPC with links and relationships with complementary technology and tools in the areas of virtualization, data visualization, data analysis and simulation, aligned with industrial-driven application fields, creating a value chain for final users and practitioners. 6. Enhancing HPC R&D policy dialogue between policy makers and stakeholders from EU and Latin American HPC communities; develop a Road Map towards a Joint Strategy in HPC R&D. At the end of the project we expect a fully functioning network focusing on activities to support and to promote coordination of the HPC and Computational Science research between EU and LA.

News Article | December 27, 2016
Site: www.eurekalert.org

The Biophysical Society has announced the winners of its international travel grants to attend the Biophysical Society's 61st Annual Meeting in New Orleans, February 11-15, 2017. The purpose of these awards is to foster and initiate further interaction between American biophysicists and scientists working in countries experiencing financial difficulties. Recipients of this competitive award are chosen based on scientific merit and their proposed presentation at the meeting. They will be honored at a reception on Sunday, February 12 at the Ernest N. Morial Convention Center. The 2017 recipients of the International Travel Award, along with their institutional affiliation and abstract title, are listed below. Ana F. Guedes, Institute of Molecular Medicine, Portugal, ATOMIC FORCE MICROSCOPY AS A TOOL TO EVALUATE THE RISK OF CARDIOVASCULAR DISEASES IN PATIENTS. Karishma Bhasne Mohali, Indian Institute of Science Education and Research (IISER), A TALE OF TWO AMYLOIDOGENIC INTRINSICALLY DISORDERED PROTEINS: INTERPLAY OF TAU AND α-SYNUCLEIN. Chan Cao, East China University of Science and Technology, DIRECT IDENTIFICATION OF ADENINE, THYMINE, CYTOSINE AND GUANINE USING AEROLYSIN NANOPORE. Venkata Reddy Chirasani, Indian Institute of Technology Madras, LIPID TRANSFER MECHANISM OF CETP BETWEEN HDL AND LDL: A COARSEGRAINED SIMULATION STUDY. Assaf Elazar, Weizmann Institute of Science, Israel, DECIPHERING MEMBRANE PROTEIN ENERGETICS USING DEEP SEQUENCING; TOWARDS ROBUST DESIGN AND STRUCTURE PREDICTION OF MEMBRANE PROTEINS. Manuela Gabriel, University of Buenos Aires, Argentina, 3D ORBITAL TRACKING OF SINGLE GOLD NANOPARTICLES: A NEW APPROACH TO STUDY VESICLE TRAFFICKING IN CHROMAFFIN CELLS. Farah Haque National Centre for Biological Sciences, India, A NEW HUMANIZED MOUSE MODEL FOR STUDYING INHERITED CARDIOMYOPATHIC MUTATIONS IN THE MYH7 GENE. Stephanie Heusser, Stockholm University, Switzerland, STRUCTURAL AND FUNCTIONAL EVIDENCE FOR MULTI-SITE ALLOSTERY MEDIATED BY GENERAL ANESTHETICS IN A MODEL LIGAND-GATED ION CHANNEL. Amir Irani, Massey University, New Zealand, HOMOGALACTURONANS ILLUMINATE THE ROLE OF COUNTERION CONDENSATION IN POLYELECTROLYTE TRANSPORT. Olfat Malak, University of Nantes, France, HIV-TAT INDUCES A DECREASE IN IKR AND IKS VIA REDUCTION IN PHOSPHATIDYLINOSITOL-(4,5)-BISPHOSPHATE AVAILABILITY. CONFORMATIONAL TRANSITION AND ASSEMBLY OF E.COLI CYTOLYSIN A PORE FORMING TOXIN BY SINGLE MOLECULE FLUORESCENCE. Sabrina Sharmin, Shizuoka University, Japan, EFFECTS OF LIPID COMPOSITIONS ON THE ENTRY OF CELL PENETRATING PEPTIDE OLIGOARGININE INTO SINGLE VESICLES. Xin Shi, East China University of Science and Technology, DIRECT OBSERVATION OF SINGLE BIOPOLYMER FOLDING AND UNFOLDING PROCESS BY SOLIDSTATE NANOPORE. Omar Alijevic, University of Lausanne, Switzerland, ANALYSIS OF GATING OF ACID-SENSING ION CHANNELS (ASICS) UNDER RAPID AND SLOW PH CHANGES. Swapna Bera, Bose Institute, India, BIOPHYSICAL INSIGHTS INTO THE MEMBRANE INTERACTION OF THE CORE AMYLOID-FORMING Aβ40 FRAGMENT K16-K28 AND ITS ROLE IN THE PATHOGENESIS OF ALZHEIMER'S DISEASE. Anais Cassaignau, University College London, United Kingdom, STRUCTURAL INVESTIGATION OF AN IMMUNOGLOBULIN DOMAIN ON THE RIBOSOME USING NMR SPECTROSCOPY. Bappaditya Chandra, Tata Institute of Fundamental Research, India, SECONDARY STRUCTURE FLIPPING CONNECTED TO SALT-BRIDGE FORMATION CONVERTS TOXIC AMYLOID-β40 OLIGOMERS TO FIBRILS. Gayathri Narasimhan, Cinvestav, Mexico, ANTIHYPERTROPHIC EFFECTS OF DIAZOXIDE INVOLVES CHANGES IN MIR-132 EXPRESSION IN ADULT RAT CARDIOMYCYTES. Giulia Paci, European Molecular Biology Laboratory, Germany, FOLLOWING A GIANT'S FOOTSTEPS: SINGLE-PARTICLE AND SUPER-RESOLUTION APPROACHES TO DECIPHER THE NUCLEAR TRANSPORT OF HEPATITIS B VIRUS CAPSIDS. Bizhan Sharopov, Bogomoletz Institute of Physiology National Academy of Sciences of Ukraine, DISSECTING LOCAL AND SYSTEMIC EFFECTS OF TRPV1 ON BLADDER CONTRACTILITY IN DIABETES. Chao Sun, East China Normal University, FUNCTION OF BACTERIORUBERIN IN ARCHAERHODOPSIN 4, FROM EXPRESSION TO CHARACTERIZATION. Matthew Batchelor, University of Leeds, United Kingdom STRUCTURAL DYNAMICS IN THE MYOSIN 7A SINGLE α-HELIX DOMAIN. Daniel Havelka, Czech Academy of Sciences, MICROVOLUME DIELECTRIC SPECTROSCOPY AND MOLECULAR DYNAMICS OF AMINO ACIDS. Ivan Kadurin, University College London, United Kingdom, INVESTIGATION OF THE PROTEOLYTIC CLEAVAGE OF α2δ SUBUNITS: A MECHANISTIC SWITCH FROM NHIBITION TO ACTIVATION OF VOLTAGE-GATED CALCIUM CHANNELS? Linlin Ma, University of Queensland, Australia, NOVEL HUMAN EAG CHANNEL ANTAGONISTS FROM SPIDER VENOMS. Ivana Malvacio, University of Cagliari, Italy, MOLECULAR INSIGHTS ON THE RECOGNITION OF SUBSTRATES BY THE PROMISCUOUS EFFLUX PUMP ACRB. Cristina Moreno Vadillo, Cardiovascular Research Institute Maastricht, Netherlands, RESTORING DEFECTIVE CAMP-DEPENDENT UPREGULATION IN LONG-QT SYNDROME TYPE-1 THROUGH INTERVENTIONS THAT PROMOTE IKS CHANNEL OPENING. Melanie Paillard, Claude Bernard University Lyon 1, France, TISSUE-SPECIFIC MITOCHONDRIAL DECODING OF CYTOPLASMIC CA2+ SIGNALS IS CONTROLLED BY THE STOICHIOMETRY OF MICU1/2 AND MCU. Mohammed Mostafizur Rahman, Institute for Stem Cell Biology and Regenerative Medicine, India, STRESS-INDUCED DIFFERENTIAL REGULATION LEADS TO DECOUPLING OF THE ACTIVITY BETWEEN MPFC AND AMYGDALA. Marcin Wolny, University of Leeds, United Kingdom, DESIGN AND CHARACTERIZATION OF LONG AND STABLE DE NOVO SINGLE α-HELIX DOMAINS. Elvis Pandzic, University of New South Wales, Australia, VELOCITY LANDSCAPES RESOLVE MULTIPLE DYNAMICAL POPULATIONS FROM FLUORESCENCE IMAGE TIME SERIES. 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.

Curtin P.C.P.,City University of New York | Medan V.,City University of New York | Medan V.,University of Buenos Aires | Neumeister H.,City University of New York | And 2 more authors.
Journal of Neuroscience | Year: 2013

Here we applied behavioral testing, pharmacology, and in vivo electrophysiology to determine the function of the serotonin 5-HT5A receptor in goldfish startle plasticity and sensorimotor gating. In an initial series of behavioral experiments, we characterized the effects of a selective 5-HT5A antagonist, SB-699551 (3-cyclopentyl-N-[2-(dimethylamino)ethyl]-N-[(4-{[(2-phenylethyl)amino]methyl}-4- biphenylyl)methyl]propanamide dihydrochloride), on prepulse inhibition of the acoustic startle response. Those experiments showed a dose-dependent decline in startle rates in prepulse conditions. Subsequent behavioral experiments showed that SB-699551 also reduced baseline startle rates (i.e., without prepulse). To determine the cellular mechanisms underlying these behaviors, we tested the effects of two distinct selective 5-HT5A antagonists, SB-699551 and A-843277 (N-(2,6-dimethoxybenzyl)-N'[4-(4-fluorophenyl)thiazol- 2-yl]guanidine), on the intrinsic membrane properties and synaptic sound response of the Mauthner cell (M-cell), the decision-making neuron of the startle circuit. Auditory-evoked postsynaptic potentials recorded in the M-cell were similarly attenuated after treatment with either 5-HT5A antagonist (SB-699551, 26.41±3.98% reduction; A-843277, 17.52±6.24% reduction). This attenuation was produced by a tonic (intrinsic) reduction in M-cell input resistance, likely mediated by a Cl- conductance, that added to the extrinsic inhibition produced by an auditory prepulse. Interestingly, the effector mechanisms underlying neural prepulse inhibition itself were unaffected by antagonist treatment. In summary, these results provide an in vivo electrophysiological characterization of the 5-HT5A receptor and its behavioral relevance and provide a new perspective on the interaction of intrinsic and extrinsic modulatory mechanisms in startle plasticity and sensorimotor gating. © 2013 the authors.

Aldazabal G.,Bariloche Atomic Center | Baron W.,CONICET | Marques D.,CEA Saclay Nuclear Research Center | Nunez C.,CONICET | Nunez C.,University of Buenos Aires
Journal of High Energy Physics | Year: 2011

We perform a generalized Scherk-Schwarz dimensional reduction of Double Field Theory on a twisted double torus. The four dimensional effective action is shown to exactly reproduce the bosonic electric sector of gauged N = 4 supergravity. We present explicit expressions for the gaugings in terms of the twists, and analyze the associated string backgrounds. This framework provides a higher dimensional origin of the gaugings in terms of generalized fluxes.

Cojan Y.,University of Buenos Aires | Cojan Y.,University of Geneva | Archimi A.,University of Geneva | Cheseaux N.,University of Geneva | And 2 more authors.
Cortex | Year: 2013

Cognitive hypotheses of hypnotic phenomena have proposed that executive attentional systems may be either inhibited or overactivated to produce a selective alteration or disconnection of some mental operations. Recent brain imaging studies have reported changes in activity in both medial (anterior cingulate) and lateral (inferior) prefrontal areas during hypnotically induced paralysis, overlapping with areas associated with attentional control as well as inhibitory processes. To compare motor inhibition mechanisms responsible for paralysis during hypnosis and those recruited by voluntary inhibition, we used electroencephalography (EEG) to record brain activity during a modified bimanual Go-Nogo task, which was performed either in a normal baseline condition or during unilateral paralysis caused by hypnotic suggestion or by simulation (in two groups of participants, each tested once with both hands valid and once with unilateral paralysis). This paradigm allowed us to identify patterns of neural activity specifically associated with hypnotically induced paralysis, relative to voluntary inhibition during simulation or Nogo trials. We used a topographical EEG analysis technique to investigate both the spatial organization and the temporal sequence of neural processes activated in these different conditions, and to localize the underlying anatomical generators through minimum-norm methods. We found that preparatory activations were similar in all conditions, despite left hypnotic paralysis, indicating preserved motor intentions. A large P3-like activity was generated by voluntary inhibition during voluntary inhibition (Nogo), with neural sources in medial prefrontal areas, while hypnotic paralysis was associated with a distinctive topography activity during the same time-range and specific sources in right inferior frontal cortex. These results add support to the view that hypnosis might act by enhancing executive control systems mediated by right prefrontal areas, but does not produce paralysis via direct motor inhibition processes normally used for the voluntary suppression of actions. © 2012 Elsevier Ltd.

Gleichgerrcht E.,Institute of Cognitive Neurology INECO | Gleichgerrcht E.,University of Buenos Aires | Gleichgerrcht E.,Diego Portales University | Young L.,Boston College
PLoS ONE | Year: 2013

Is it permissible to harm one to save many? Classic moral dilemmas are often defined by the conflict between a putatively rational response to maximize aggregate welfare (i.e., the utilitarian judgment) and an emotional aversion to harm (i.e., the non-utilitarian judgment). Here, we address two questions. First, what specific aspect of emotional responding is relevant for these judgments? Second, is this aspect of emotional responding selectively reduced in utilitarians or enhanced in non-utilitarians? The results reveal a key relationship between moral judgment and empathic concern in particular (i.e., feelings of warmth and compassion in response to someone in distress). Utilitarian participants showed significantly reduced empathic concern on an independent empathy measure. These findings therefore reveal diminished empathic concern in utilitarian moral judges. © 2013 Gleichgerrcht, Young.

Aldazabal G.,Bariloche Atomic Center | Marques D.,CEA Saclay Nuclear Research Center | Nunez C.,University of Buenos Aires | Rosabal J.A.,Bariloche Atomic Center
Nuclear Physics B | Year: 2011

We analyze D=4 compactifications of Type IIB theory with generic, geometric and non-geometric, dual fluxes turned on. In particular, we study N=1 toroidal orbifold compactifications that admit an embedding of the untwisted sector into gauged N=4,8 supergravities. Truncations, spontaneous breaking of supersymmetry and the inclusion of sources are discussed. The algebraic identities satisfied by the supergravity gaugings are used to implement the full set of consistency constraints on the background fluxes. This allows to perform a generic study of N=1 vacua and identify large regions of the parameter space that do not admit complete moduli stabilization. Illustrative examples of AdS and Minkowski vacua are presented. © 2011 Elsevier B.V.

Catani S.,University of Florence | Cieri L.,University of Rome La Sapienza | de Florian D.,University of Buenos Aires | Ferrera G.,University of Milan | And 2 more authors.
Nuclear Physics B | Year: 2014

We consider QCD radiative corrections to the production of colorless high-mass systems in hadron collisions. We show that the recent computation of the soft-virtual corrections to Higgs boson production at N3LO [1] together with the universality structure of soft-gluon emission can be exploited to extract the general expression of the hard-virtual coefficient that contributes to threshold resummation at N3LL accuracy. The hard-virtual coefficient is directly related to the process-dependent virtual amplitude through a universal (process-independent) factorization formula that we explicitly evaluate up to three-loop order. As an application, we present the explicit expression of the soft-virtual N3LO corrections for the production of an arbitrary colorless system. In the case of the Drell-Yan process, we confirm the recent result of Ref. [2]. © 2014 The Authors. Published by Elsevier B.V.

Carlini M.J.,University of Buenos Aires | de Lorenzo M.S.,Rutgers University | Puricelli L.,University of Buenos Aires
Current Pharmaceutical Biotechnology | Year: 2011

This review presents recent information about the cross-talk between the tumor cells and the microenvironment in the target organ of metastasis at the premetastatic and metastatic stage. The development of metastatic foci is driven not only by the tumor cells intrinsic properties, but also by the interplay with resident and foreign cells located at particular niches in the target organ. The primary tumor modulates the metastatic target through the production of soluble factors that mobilize cells from distant organs like the bone marrow, which in turn localize in the metastatic niche. There is also strong evidence indicating that some primary tumors induce a fertile ground for the tumor cell at the target organ even before the arrival of the disseminated tumor cell (premetastatic niche). The relationship between the players of the metastatic setting is dynamic and shows a high degree of plasticity. Tumor cells change through the acquisition of genetic and/or epigenetic alterations that provide adaptive advantages and the metastatic niche is remodeled by incoming cell types or newly secreted soluble mediators, as a result a reciprocal dialogue is established that invokes new levels of molecular and cellular complexity. Unraveling the mechanisms that sustain the metastatic niche will allow a better understanding of the biology of the disseminated tumor cell, the design of new therapeutic approaches and, hopefully, the improvement of cancer patients' survival. © 2011 Bentham Science Publishers.

Alvarez E.,University of Buenos Aires | Roldb L.D.,Bariloche Atomic Center | Szynkmanc A.,National University of La Plata
Journal of High Energy Physics | Year: 2011

We perform a joint analysis of the prediction of composite Higgs models for the discrepancies of the forward-backward asymmetries of top and bottom quarks at Tevatron and LEP+SLC, respectively. We build a two sector model which can be thought as an effective low energy description of 5D warped models and choose the quantum numbers of the fermionic resonances to protect the Z-couplings of the partially composite Standard Model light quarks. We analyze the cross section, forward-backward asymmetry and invariant mass distribution of the top anti-top production at Tevatron, as well as the bottom forward-backward asymmetry and the Z-branching fraction into b-quarks at LEP and SLC, for the two sector model. In the region of the parameter space that naturally leads to the Standard Model spectrum and solves the bottom anomaly, the model improves the top forward-backward asymmetry, giving a prediction of up to 10%, and predicts a small decrease of the t̄t cross section. It also predicts non-universal corrections of the Z-couplings to the light quarks of order 0.001. © SISSA 2011.

Abramson G.,Bariloche Atomic Center | Semeshenko V.,University of Buenos Aires | Iglesias J.R.,Federal University of Rio Grande do Sul
PLoS ONE | Year: 2013

We study a simple traffic model with a non-signalized road intersection. In this model the car arriving from the right has precedence. The vehicle dynamics far from the crossing are governed by the rules introduced by Nagel and Paczuski, which define how drivers behave when braking or accelerating. We measure the average velocity of the ensemble of cars and its flow as a function of the density of cars on the roadway. An additional set of rules is defined to describe the dynamics at the intersection assuming a fraction of drivers that do not obey the rule of precedence. This problem is treated within a game-theory framework, where the drivers that obey the rule are cooperators and those who ignore it are defectors. We study the consequences of these behaviors as a function of the fraction of cooperators and defectors. The results show that cooperation is the best strategy because it maximizes the flow of vehicles and minimizes the number of accidents. A rather paradoxical effect is observed: for any percentage of defectors the number of accidents is larger when the density of cars is low because of the higher average velocity. © 2013 Abramson et al.

Chan C.X.,Rutgers University | Yang E.C.,Bigelow Laboratory for Ocean Sciences | Banerjee T.,Rutgers University | Yoon H.S.,Bigelow Laboratory for Ocean Sciences | And 3 more authors.
Current Biology | Year: 2011

The Plantae comprising red, green (including land plants), and glaucophyte algae are postulated to have a single common ancestor that is the founding lineage of photosynthetic eukaryotes [1, 2]. However, recent multiprotein phylogenies provide little [3, 4] or no [5, 6] support for this hypothesis. This may reflect limited complete genome data available for red algae, currently only the highly reduced genome of Cyanidioschyzon merolae [7], a reticulate gene ancestry [5], or variable gene divergence rates that mislead phylogenetic inference [8]. Here, using novel genome data from the mesophilic Porphyridium cruentum and Calliarthron tuberculosum, we analyze 60,000 novel red algal genes to test the monophyly of red + green (RG) algae and their extent of gene sharing with other lineages. Using a gene-by-gene approach, we find an emerging signal of RG monophyly (supported by ∼50% of the examined protein phylogenies) that increases with the number of distinct phyla and terminal taxa in the analysis. A total of 1,808 phylogenies show evidence of gene sharing between Plantae and other lineages. We demonstrate that a rich mesophilic red algal gene repertoire is crucial for testing controversial issues in eukaryote evolution and for understanding the complex patterns of gene inheritance in protists. © 2011 Elsevier Ltd.

Tencer B.,University of Buenos Aires | Rusticucci M.,University of Buenos Aires | Jones P.,University of East Anglia | Lister D.,University of East Anglia
Bulletin of the American Meteorological Society | Year: 2011

A southeastern South American daily high-resolution gridded dataset of observed surface minimum and maximum temperature for 1961-2000 is presented. The interpolation methodology was adapted from the one developed for Europe as part of the EU FP6 ENSEMBLE-based predictions of climate changes and their impacts (ENSEMBLES) project. The gridded dataset presented in this study was developed from daily surface minimum and maximum temperature data observed at meteorological stations from Argentina, Brazil, Paraguay, and Uruguay, compiled during the EU FP6 CLARIS project, with additional Brazilian data gathered after the end of that project. Before data were entered into the CLARIS database, they were quality controlled following a common set of tests. The interpolation methodology used to convert irregularly spaced observations at station points to regular grid boxes was developed during the EU FP6 ENSEMBLES project and consists of a three-step procedure involving the use of the kriging method.

Gleichgerrcht E.,Institute of Cognitive Neurology INECO | Gleichgerrcht E.,University of Buenos Aires | Gleichgerrcht E.,Diego Portales University | Decety J.,University of Chicago
PLoS ONE | Year: 2013

To better understand clinical empathy and what factors can undermine its experience and outcome in care-giving settings, a large-scale study was conducted with 7,584 board certified practicing physicians. Online validated instruments assessing different aspects of empathy, distress, burnout, altruistic behavior, emotional awareness, and well-being were used. Compassion satisfaction was strongly associated with empathic concern, perspective taking and altruism, while compassion fatigue (burnout and secondary traumatic stress) was more closely related to personal distress and alexithymia. Gender had a highly selective effect on empathic concern, with women displaying higher values, which led to a wide array of negative and devalued feelings. Years of experience did not influence dispositional measures per se after controlling for the effect of age and gender. Participants who experienced compassion fatigue with little to no compassion satisfaction showed the highest scores on personal distress and alexithymia as well as the strongest indicators of compassion fatigue. Physicians who have difficulty regulating their negative arousal and describing and identifying emotions seem to be more prone to emotional exhaustion, detachment, and a low sense of accomplishment. On the contrary, the ability to engage in self-other awareness and regulate one's emotions and the tendency to help others, seem to contribute to the sense of compassion that comes from assisting patients in clinical practice. © 2013 Gleichgerrcht, Decety.

Catani S.,University of Florence | Cieri L.,University of Rome La Sapienza | de Florian D.,University of Buenos Aires | Ferrera G.,University of Milan | And 2 more authors.
Nuclear Physics B | Year: 2014

We consider QCD radiative corrections to the production of colorless high-mass systems in hadron collisions. The logarithmically-enhanced contributions at small transverse momentum are treated to all perturbative orders by a universal resummation formula that depends on a single process-dependent hard factor. We show that the hard factor is directly related to the all-order virtual amplitude of the corresponding partonic process. The direct relation is universal (process-independent), and it is expressed by an all-order factorization formula that we explicitly evaluate up to the next-to-next-to-leading order (NNLO) in QCD perturbation theory. Once the NNLO scattering amplitude is available, the corresponding hard factor is directly determined: it controls NNLO contributions in resummed calculations at full next-to-next-to-leading logarithmic accuracy, and it can be used in applications of the q T subtraction formalism to perform fully-exclusive perturbative calculations up to NNLO. The universality structure of the hard factor and its explicit NNLO form are also extended to the related formalism of threshold resummation. © 2014 The Authors.

Reynoso E.M.,Institute Astronomia y Fisica Del Espacio IAFE | Reynoso E.M.,University of Buenos Aires | Hughes J.P.,Rutgers University | Moffett D.A.,Furman University
Astronomical Journal | Year: 2013

Radio polarization observations provide essential information on the degree of order and orientation of magnetic fields, which themselves play a key role in the particle acceleration processes that take place in supernova remnants (SNRs). Here we present a radio polarization study of SN 1006, based on combined Very Large Array and Australia Telescope Compact Array observations at 20 cm that resulted in sensitive images with an angular resolution of 10 arcsec. The fractional polarization in the two bright radio and X-ray lobes of the SNR is measured to be 0.17, while in the southeastern sector, where the radio and non-thermal X-ray emission are much weaker, the polarization fraction reaches a value of 0.6 ± 0.2, close to the theoretical limit of 0.7. We interpret this result as evidence of a disordered, turbulent magnetic field in the lobes, where particle acceleration is believed to be efficient, and a highly ordered field in the southeast, where the acceleration efficiency has been shown to be very low. Utilizing the frequency coverage of our observations, an average rotation measure of ∼12 rad m-2 is determined from the combined data set, which is then used to obtain the intrinsic direction of the magnetic field vectors. While the orientation of magnetic field vectors across the SNR shell appear to be radial, a large fraction of the magnetic vectors lie parallel to the Galactic plane. Along the highly polarized southeastern rim, the field is aligned tangent to the shock, and therefore also nearly parallel to the Galactic plane. These results strongly suggest that the ambient field surrounding SN 1006 is aligned with this direction (i.e., from northeast to southwest) and that the bright lobes are due to a polar cap geometry. Our study establishes that the most efficient particle acceleration and generation of magnetic turbulence in SN 1006 is attained for shocks in which the magnetic field direction and shock normal are quasi-parallel, while inefficient acceleration and little to no generation of magnetic turbulence are obtained for the quasi-perpendicular case. © 2013. The American Astronomical Society. All rights reserved.

Catani S.,University of Florence | Cieri L.,University of Buenos Aires | De Florian D.,University of Buenos Aires | Ferrera G.,University of Milan | And 2 more authors.
Physical Review Letters | Year: 2012

We consider direct diphoton production in hadron collisions, and we compute the next-to-next-to-leading order QCD radiative corrections at the fully differential level. Our calculation uses the q T subtraction formalism, and it is implemented in a parton-level Monte Carlo program. The program allows the user to apply arbitrary kinematical cuts on the final-state photons and the associated jet activity and to compute the corresponding distributions in the form of bin histograms. We present selected numerical results related to Higgs boson searches at the LHC and corresponding results at the Tevatron. © 2012 American Physical Society.

Di Russo N.V.,University of Florida | Di Russo N.V.,University of Buenos Aires | Estrin D.A.,University of Buenos Aires | Marti M.A.,University of Buenos Aires | Roitberg A.E.,University of Florida
PLoS Computational Biology | Year: 2012

The acid-base behavior of amino acids is an important subject of study due to their prominent role in enzyme catalysis, substrate binding and protein structure. Due to interactions with the protein environment, their pKas can be shifted from their solution values and, if a protein has two stable conformations, it is possible for a residue to have different "microscopic", conformation-dependent pKa values. In those cases, interpretation of experimental measurements of the pKa is complicated by the coupling between pH, protonation state and protein conformation. We explored these issues using Nitrophorin 4 (NP4), a protein that releases NO in a pH sensitive manner. At pH 5.5 NP4 is in a closed conformation where NO is tightly bound, while at pH 7.5 Asp30 becomes deprotonated, causing the conformation to change to an open state from which NO can easily escape. Using constant pH molecular dynamics we found two distinct microscopic Asp30 pKas: 8.5 in the closed structure and 4.3 in the open structure. Using a four-state model, we then related the obtained microscopic values to the experimentally observed "apparent" pKa, obtaining a value of 6.5, in excellent agreement with experimental data. This value must be interpreted as the pH at which the closed to open population transition takes place. More generally, our results show that it is possible to relate microscopic structure dependent pKa values to experimentally observed ensemble dependent apparent pKas and that the insight gained in the relatively simple case of NP4 can be useful in several more complex cases involving a pH dependent transition, of great biochemical interest. © 2012 Di Russo et al.

Jiang P.,University of Michigan | Ventura A.C.,University of Buenos Aires | Sontag E.D.,Rutgers University | Merajver S.D.,University of Michigan | And 2 more authors.
Science Signaling | Year: 2011

Biological signal transduction networks are commonly viewed as circuits that pass along information - in the process amplifying signals, enhancing sensitivity, or performing other signal-processing tasks - to transcriptional and other components. Here, we report on a "reverse-causality" phenomenon, which we call load-induced modulation. Through a combination of analytical and experimental tools, we discovered that signaling was modulated, in a surprising way, by downstream targets that receive the signal and, in doing so, apply what in physics is called a load. Specifically, we found that non-intuitivechanges in response dynamics occurred for a covalent modification cycle when load was present.Loading altered the response time of a system, depending on whether the activity of one of the enzymeswas maximal and the other was operating at its minimal rate or whether both enzymes were operating atsubmaximal rates. These two conditions, which we call "limit regime" and "intermediate regime," wereassociated with increased or decreased response times, respectively. The bandwidth, the range of frequencyin which the system can process information, decreased in the presence of load, suggesting thatdownstream targets participate in establishing a balance between noise-filtering capabilities and a circuit'sability to process high-frequency stimulation. Nodes in a signaling network are not independentrelay devices, but rather are modulated by their downstream targets.

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.

News Article | December 15, 2016
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VANCOUVER, BRITISH COLUMBIA--(Marketwired - Dec. 15, 2016) - Argentina Lithium & Energy Corp. (TSX VENTURE:LIT)(FRANKFURT:OAY1)(WKN:A0RK7E)(OTCQB:PNXLF) ("Argentina Lithium" or the "Company") has appointed Dr. Daniel Galli as Director of Technical Operations effective November 28, 2016. Dr. Galli is a highly respected professional mining entrepreneur with more than 40 years' experience working on mining projects and processing of industrial minerals contained in the salt mines of the Argentine Puna and the Bolivian Altiplano, within the "Lithium Triangle". Among Dr. Galli's greatest achievements is the development of processes for the production of lithium carbonate and battery grade lithium hydroxide from the brines contained in the salt mines. His wide range of experience from early stage exploration to production has made him one of the highest profile consultants in the lithium industry in Argentina. Dr. Daniel Galli graduated with a degree in Chemical Science with an emphasis on Industrial Chemistry from the University of Buenos Aires (Argentina) and holds the title of Doctor of Philosophy (PhD) awarded by Macquarie University, Sydney (Australia). Currently, Dr. Galli is a Professor of Thermodynamics at the Faculty of Engineering at the National University of Jujuy, Argentina. During the period 2006 - 2013, Dr. Galli served as the Technical Director of ADY Resources Limited's "Rincón Project", taking it from the initial stage of consolidation of mining properties through to conducting exploration, permitting and production of lithium carbonate employing proprietary patented processes that he developed. Dr. Galli has several reports and patents and has participated as a speaker at numerous symposiums relating to the production of lithium carbonate from brines and the design of appropriate processes for use in the Argentine Puna, the Bolivian Altiplano and the Atacama Desert in Chile. "We are extremely pleased to welcome Dr. Galli to Argentina Lithium," said Nikolaos Cacos, President and C.E.O. "His stature and proven track record in building and successfully operating large-scale lithium brine operations is a tremendous asset to our company." All processes developed by Dr. Galli favor the use of clean energy, minimizing environmental impact while maximizing recovery not only of lithium but also other chemical elements of interest contained in the brines. Pursuant to the terms of an Amended and Restated Consulting Agreement dated as of November 28, 2016 (the "Consulting Agreement") made between the Company and Daniel Galli (the "Consultant"), Dr. Galli will provide advisory services to the Company and its wholly owned subsidiary, Argentina Litio y Energia S.A., which services will include the evaluation of mining properties, preparation of technical reports, reviews of and presentations of new projects, training programs and technical field visits. The Company may elect to pay a portion of the Consultant's compensation by the issuance of common shares of the Company, having up to a maximum deemed value of US$4,000 per month. Any such common shares shall be issued on a quarterly basis at a deemed price equal to the volume weighted average trading price of the Company's common shares over the twenty trading days on the TSX Venture Exchange ("TSXV") immediately preceding the last day of the applicable quarterly period, which shall not be less than the Discounted Market Price (as defined by the TSXV policies) as at the date that the Company elects to issue common shares to the Consultant, in respect of any such quarterly period. The Consulting Agreement is subject to the approval of the TSXV and all share issuances thereunder will also be subject to TSXV approval. ON BEHALF OF THE BOARD Neither TSX Venture Exchange nor its Regulation Services Provider (as that term is defined in policies of the TSX Venture Exchange) accepts responsibility for the adequacy or accuracy of this release. This news release may contain forward-looking statements. Forward-looking statements address future events and conditions and therefore involve inherent risks and uncertainties. Actual results may differ materially from those currently anticipated in such statements. Readers are encouraged to refer to the Company's public disclosure documents for a more detailed discussion of factors that may impact expected future results. The Company undertakes no obligation to publicly update or revise any forward-looking statements.

Lochbihler H.,Louisenthal GmbH | Depine R.A.,University of Buenos Aires
Applied Optics | Year: 2012

Electromagnetic resonances on metallic slit gratings induced by TM polarized incident light have been investigated and physically interpreted. We have developed an electromagnetic model imposing surface impedance boundary conditions on the metallic grating surface from which we derive simple formulas explaining all physical properties of these resonances. It is demonstrated that Fabry-Perot (or cavity) resonances are generated by the zeroth slit mode yielding extraordinary transmission. For very narrow slits, the resonant H-field is squeezed to the slit walls and causes enhanced power losses. The excitation of surface plasmon polaritons (SPPs), however, is generated by two mode coupling. SPPs are linked to sharp absorption peaks and dips in transmittance. It is shown that these phenomena are primarily caused by the interaction of the electromagnetic fields with the finite conducting slit walls. These findings have been confirmed by measured transmittance data of gold gratings with periods of 0.5 μm, 1 μm, and 2 μm. © 2012 Optical Society of America.

Arbuzov A.B.,Joint Institute for Nuclear Research | Cirilo-Lombardo D.J.,University of Buenos Aires
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2016

Radiatively induced symmetry breaking is considered for a toy model with one scalar and one fermion field unified in a superfield. It is shown that the classical quartic self-interaction of the superfield possesses a quantum infrared singularity. Application of the Coleman-Weinberg mechanism for effective potential leads to the appearance of condensates and masses for both scalar and fermion components. That induces a spontaneous breaking of the initial classical symmetries: the supersymmetry and the conformal one. The energy scales for the scalar and fermion condensates appear to be of the same order, while the renormalization scale is many orders of magnitude higher. A possibility to relate the considered toy model to conformal symmetry breaking in the Standard Model is discussed. © 2016 The Authors.

Cirilo-Lombardo D.J.,University of Buenos Aires | Cirilo-Lombardo D.J.,Joint Institute for Nuclear Research
International Journal of Geometric Methods in Modern Physics | Year: 2016

It is commonly claimed in the recent literature that certain solutions to wave equations of positive energy of Dirac-type with internal variables are characterized by a non-thermal spectrum. As part of that statement, it was said that the transformations and symmetries involved in equations of such type corresponded to a particular representation of the Lorentz group. In this paper, we give the general solution to this problem emphasizing the interplay between the group structure, the corresponding algebra and the physical spectrum. This analysis is completed with a strong discussion and proving that: (i) the physical states are represented by coherent states; (ii) the solutions in [Yu. P. Stepanovsky, Nucl. Phys. B (Proc. Suppl.) 102 (2001) 407-411; 103 (2001) 407-411] are not general, (iii) the symmetries of the considered physical system in [Yu. P. Stepanovsky, Nucl. Phys. B (Proc. Suppl.) 102 (2001) 407-411; 103 (2001) 407-411] (equations and geometry) do not correspond to the Lorentz group but to the fourth covering: the Metaplectic group Mp(n). © 2016 World Scientific Publishing Company.

Prieto-Marquez A.,American Museum of Natural History | Salinas G.C.,University of Buenos Aires
Journal of Vertebrate Paleontology | Year: 2010

Hadrosaurids form the most diverse and derived clade of ornithopod dinosaurs. Although well represented in Asia and North America, its presence in South America is known only from rare and fragmentary remains that are poorly documented and mostly unstudied. As a result, the impact of these animals on the phylogenetics and biogeography of hadrosaurids as a whole is poorly known. Here, we provide a revised and complete osteology of the type specimens and hypodigms for the only two taxa known from South America, Secernosaurus koerneri and Kritosaurus australis. Likewise, we infer the phylogenetic position and historical biogeography of South American hadrosaurids using a nearly complete taxonomic sampling of hadrosaurid species. Parsimony methods were used to infer phylogenetic relationships, whereas Fitch parsimony and Dispersal-Vicariance analyses were implemented to reconstruct ancestral areas. Kritosaurus australis is regarded as a junior synonym of Secernosaurus koerneri, based on a combination of iliac and pubic characters unique to these two taxa. Inclusion of 5. koerneri within the genus Kritosaurus is not supported by the phylogenetic analysis. S. koerneri is inferred to be a member of the Kritosaurus-Gryposaurus clade within Saurolophinae, as the sister taxon to the Argentinean unnamed hadrosaurid from Salitral Moreno. Another unnamed hadrosaurid from Big Bend National Park, Texas, is positioned as the closest outgroup to the South American clade. The results of this biogeographical analysis supports the hypothesis that the Secernosaurus clade originated in South America during the late Campanian after a dispersal event (probably followed by vicariance) from southern North America before the end of that geologic stage. © 2010 by the Society of Vertebrate Paleontology.

Fernandez N.,CSIC - Doñana Biological Station | Paruelo J.M.,University of Buenos Aires | Delibes M.,CSIC - Doñana Biological Station
Remote Sensing of Environment | Year: 2010

Spatial heterogeneity in ecosystem functioning is a key component of ecological variability requiring special attention in the context of global change. A large history of human use has produced high physiognomic heterogeneity in Mediterranean ecosystems. However, the consequences for ecosystem functioning remain insufficiently understood. We analyzed spectral indicators of matter and energy fluxes in the land surface to classify the functional ecosystem heterogeneity in a Mediterranean region covering different management histories and protection types. We specifically analyzed the spatial variability in seasonal and annual patterns in the Normalized Difference Vegetation Index (NDVI), surface temperature (Ts) and albedo from five Landsat ETM images. Then we classified numerically this variability into ecosystem functional types (EFTs) and explored their seasonal dynamics in terms of photosynthetic radiation absorption and evapotranspiration. We identified eight main EFTs with ecologically relevant differences including contrasting dynamics in fPAR seasonality, great variation in incoming radiation reflection and differing evapotranspiration rates, particularly during the water-limitation period. Functional variability in natural vegetation mostly consisted in dissimilar annual rates of NDVI and albedo, whereas differences in seasonality were more evident in transformed areas. Similarly, the spatial distribution of EFTs was partly associated to protection, with two EFTs exclusive of protected areas and comparatively higher functional diversity in humanized areas. Landform effects on water availability in protected areas and human activities under different ecological settings were seemingly responsible for the large functional diversity of the region. We advocate for the explicit incorporation of multifunctional ecosystem heterogeneity in ecosystem management and monitoring designs. © 2009 Elsevier Inc. All rights reserved.

Cieri L.,University of Rome La Sapienza | Coradeschi F.,University of Florence | de Florian D.,University of Buenos Aires
Journal of High Energy Physics | Year: 2015

Abstract: We consider the transverse-momentum (qT) distribution of a diphoton pair produced in hadron collisions. At small values of qT, we resum the logarithmically-enhanced perturbative QCD contributions up to next-to-next-to-leading logarithmic accuracy. At intermediate and large values of qT, we consistently combine resummation with the known next-to-leading order perturbative result. All perturbative terms up to order αS 2 are included in our computation which, after integration over qT, reproduces the known next- to-next-to-leading order result for the diphoton pair production total cross section. We present a comparison with LHC data and an estimate of the perturbative accuracy of the theoretical calculation by performing the corresponding variation of scales. In general we observe that the effect of the resummation is not only to recover the predictivity of the calculation at small transverse momentum, but also to improve substantially the agreement with the experimental data. © 2015, The Author(s).

Verdini A.,Observatoire Royale de Belgique | Velli M.,University of Florence | Velli M.,Jet Propulsion Laboratory | Matthaeus W.H.,University of Delaware | And 2 more authors.
Astrophysical Journal Letters | Year: 2010

A model is presented for generation of fast solar wind in coronal holes, relying on heating that is dominated by turbulent dissipation of MHD fluctuations transported upward in the solar atmosphere. Scale-separated transport equations include large-scale fields, transverse Alfvénic fluctuations, and a small compressive dissipation due to parallel shears near the transition region. The model accounts for proton temperature, density, wind speed, and fluctuation amplitude as observed in remote sensing and in situ satellite data. © 2010. The American Astronomical Society. All rights reserved..

Karadayian A.G.,University of Buenos Aires | Busso M.J.,University of Buenos Aires | Feleder C.,Albany College of Pharmacy and Health Sciences | Cutrera R.A.,University of Buenos Aires
Behavioural Brain Research | Year: 2013

Alcohol hangover is a temporary state described as the unpleasant next-day effects after binge-like drinking. Hangover begins when ethanol is absent in plasma and is characterized by physical and psychological symptoms. Affective behavior is impaired during the acute phase of alcohol intoxication; however, no reports indicate if similar effects are observed during withdrawal. The aim of this work was to study the time-extension and possible fluctuations in affective behavior during a hangover episode. Male Swiss mice were injected i.p. either with saline (control group) or with ethanol (3.8. g/kg BW) (hangover group). Anxiety, fear-related behavior and despair phenotype were evaluated at a basal point (ZT0) and every 2. h up to 20. h after blood alcohol levels were close to zero (hangover onset). Also, anhedonia signs and pain perception disabilities were studied. Mice exhibited an increase in anxiety-like behavior during 4. h and 14. h after hangover onset when evaluated by the elevated-plus maze and open field test respectively (p<. 0.05). Fear-related behavior was detected in hangover animals by the increase of freezing and decrease of line crossings and rearing frequency during 16. h after hangover onset (p<. 0.001). Depression signs were found in hangover mice during 14. h (p<. 0.05). Hangover mice showed a significant decrease in pain perception when tested by tail immersion test at the beginning of hangover (p<. 0.05). Our findings demonstrate a time-extension between 14 and 16. h for hangover affective impairments. This study shows the long lasting effects of hangover over the phase of ethanol intoxication. © 2013 Elsevier B.V.

Bozzi G.,University of Milan | Catani S.,University of Florence | Ferrera G.,University of Florence | de Florian D.,University of Buenos Aires | Grazzini M.,University of Florence
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2011

We consider the transverse-momentum (qT) distribution of Drell-Yan lepton pairs produced in hadron collisions. At small values of qT, we resum the logarithmically-enhanced perturbative QCD contributions up to next-to-next-to-leading logarithmic accuracy. At intermediate and large values of qT, we consistently combine resummation with the known next-to-leading order perturbative result. All perturbative terms up to order αS 2 are included in our computation which, after integration over qT, reproduces the known next-to-next-to-leading order result for the Drell-Yan total cross section. We show and discuss the reduction in the scale dependence of the results with respect to lower-order calculations, estimating the corresponding perturbative uncertainty. We present a preliminary comparison with Tevatron Run II data. © 2010 Elsevier B.V.

Crocker J.,Howard Hughes Medical Institute | Abe N.,Columbia University | Rinaldi L.,Columbia University | McGregor A.P.,Oxford Brookes University | And 12 more authors.
Cell | Year: 2015

In animals, Hox transcription factors define regional identity in distinct anatomical domains. How Hox genes encode this specificity is a paradox, because different Hox proteins bind with high affinity in vitro to similar DNA sequences. Here, we demonstrate that the Hox protein Ultrabithorax (Ubx) in complex with its cofactor Extradenticle (Exd) bound specifically to clusters of very low affinity sites in enhancers of the shavenbaby gene of Drosophila. These low affinity sites conferred specificity for Ubx binding in vivo, but multiple clustered sites were required for robust expression when embryos developed in variable environments. Although most individual Ubx binding sites are not evolutionarily conserved, the overall enhancer architecture - clusters of low affinity binding sites - is maintained and required for enhancer function. Natural selection therefore works at the level of the enhancer, requiring a particular density of low affinity Ubx sites to confer both specific and robust expression. © 2015 Elsevier Inc.

Catani S.,University of Florence | De Florian D.,University of Buenos Aires | De Florian D.,University of Zürich | Rodrigo G.,Institute Fisica Corpuscular
Journal of High Energy Physics | Year: 2012

We consider the singular behaviour of QCD scattering amplitudes in kinematical configurations where two or more momenta of the external partons become collinear. At the tree level, this behaviour is known to be controlled by factorization formulae in which the singular collinear factor is universal (process independent). We show that this strict (process-independent) factorization is not valid at one-loop and higher-loop orders in the case of the collinear limit in space-like regions (e.g., collinear radiation from initialstate partons). We introduce a generalized version of all-order collinear factorization, in which the space-like singular factors retain some dependence on the momentum and colour charge of the non-collinear partons. We present explicit results on one-loop and two-loop amplitudes for both the two-parton and multiparton collinear limits. At the level of squared amplitudes and, more generally, cross sections in hadron-hadron collisions, the violation of strict collinear factorization has implications on the non-abelian structure of logarithmically-enhanced terms in perturbative calculations (starting from the next-tonext-to-leading order) and on various factorization issues of mass singularities (starting from the next-to-next-to-next-to-leading order). © SISSA 2012.

Palacios-Jaraquemada J.M.,Center for Medical Education and Clinical Research | Palacios-Jaraquemada J.M.,Scientific South Foundation | Palacios-Jaraquemada J.M.,University of Buenos Aires
Best Practice and Research: Clinical Obstetrics and Gynaecology | Year: 2013

In the past decade, the incidence of placenta praevia and placenta accreta has increased and seems to be associated with induced labour, termination of pregnancy, caesarean section and pregnancy at older age. These factors imply some degree of tissue damage, which can modify the decidualisation process, and produce excessive vascular remodelling. Placenta praevia and accreta are mainly located in the lower segment, a place that predisposes to persistent uterine bleeding because of the development of new vessels and because it is a poorly contractile area of the uterus. The complexity, determined by tissue destruction, newly formed vessels, and vascular invasion of surrounding tissues, warrants multi-disciplinary management. When resective procedures are undertaken, a suitable plan to tackle surgical problems allows better control of bleeding and avoids unnecessary hysterectomies. In cases of placenta accrete, and especially when skills or institutional resources are not available, leaving the placenta in situ may be the best option until definitive treatment is undertaken. © 2012 Elsevier Ltd. All rights reserved.

Kumar S.,University of Buenos Aires | Kumar S.,Indian Institute of Technology Kanpur | Gupta B.D.,Indian Institute of Technology Kanpur
Inorganic Chemistry | Year: 2011

We report the synthesis and crystallographic studies of paddlewheel-based methyl cobaloxime assembly formed from methyl cobaloxime, isonicotinic acid, and Zn(NO 3) 2. The cobaloxime units are assembled over two-dimensional metal-organic polyhedra constructed from isonicotinate and Zn metal ions. © 2011 American Chemical 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.

Holper L.,University of Zürich | Holper L.,ETH Zurich | Scholkmann F.,University of Zürich | Shalom D.E.,University of Buenos Aires | Wolf M.,University of Zürich
Cortex | Year: 2012

Motor imagery (MI) is widely used to study cognitive action control. Although, the neural simulation theory assumes that MI and motor execution (ME) share many common features, the extent of similarity and whether it spreads into the preparation phase is still under investigation. Here we asked, whether an extension of physiological mental preparation has a comparable effect on MI and ME. Data were recorded using wireless functional near-infrared spectroscopy (fNIRS) in a two-stage task design where subjects were cued with or without preparatory stimuli to either execute or imagine complex sequential thumb-finger tasks. The main finding is that the extended mental preparation has a significant positive effect on oxy-hemoglobin ({increment}[O 2Hb]) in response to MI, which is proportionally larger as that found in response to ME. Furthermore, fNIRS was capable to discriminate within each task whether it was preceded by preparatory stimuli or not. Transition from mental preparation to actual performance (ME or MI) was reflected by a dip of the fNIRS signal presumably related to underlying cortical processes changing between preparation and task performance. Statistically significant main effects of 'Preparation' and 'Task' showed that {increment}[O 2Hb] during preparation was preparation-specific, i.e., positively affected by the presence of preparatory stimuli, whereas during task performance {increment}[O 2Hb] was both preparation- and task-specific, i.e., additionally affected by the task mode. These results are particularly appealing from a practical point of view for making use of MI in neuroscientific applications. Especially neurorehabilitation and neural interfaces may benefit from utilizing positive interactions between mental preparation and MI performance. © 2011 Elsevier Srl.

Vain N.E.,University of Buenos Aires | Vain N.E.,Foundation for Maternal and Child Health FUNDASAMIN | Vain N.E.,Trinidad Palermo Private Hospital | Satragno D.S.,Foundation for Maternal and Child Health FUNDASAMIN | And 6 more authors.
The Lancet | Year: 2014

Background Delayed cord clamping allows for the passage of blood from the placenta to the baby and reduces the risk of iron deficiency in infancy. To hold the infant for more than 1 min at the level of the vagina (as is presently recommended), on the assumption that gravity affects the volume of placental transfusion, is cumbersome, might result in low compliance, and interferes with immediate contact of the infant with the mother. We aimed to assess whether gravity affects the volume of placental transfusion Methods We did a multicentre non-inferiority trial at three university-affiliated hospitals in Argentina. We obtained informed consent from healthy mothers with normal term pregnancies admitted early in labour. Vigorous babies born vaginally were randomly assigned in a 1:1 ratio by computer-generated blocks and sequentially numbered sealed opaque envelopes to be held for 2 min before clamping the umbilical cord, at the level of the vagina (introitus group) or on the mother's abdomen or chest (abdomen group). Newborn babies were weighed immediately after birth and after cord clamping. The primary outcome was the difference in weight (as a proxy of placental transfusion volume). The prespecified non-inferiority margin was 18 g (20%). We used t test and test for group comparison, and used a multivariable linear regression analysis to control for covariables.

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.

News Article | January 12, 2016
Site: cleantechnica.com

The first VELUX Natural Light lamps have begun arriving in Africa — roughly one year after the company launched a design competition based around the idea, with the support of Little Sun and NGO Plan International. The design competition was a rather successful one — with 172 proposals, from 65 different countries — so it shouldn’t be surprising things have been moving relatively fast. The VELUX Natural Light International Design Competition was decided via a high-level jury of experts in the fields of architecture, art, and design. The winning design was the proposal from Mariana Arando and Luca Fondello of the University of Buenos Aires, Argentina. As noted in a recent press release, the VELUX Group has, to date, produced and donated 14,500 of the new solar-powered lamps — as well as trained 150 local sales agents, who will be aiming to sell the lamps in off-grid communities in Senegal, Zimbabwe, and Zambia. The sales persons training was reportedly rather intensive — combining demonstrations, role-play, workshops, and other group work. “The first business training was very successful. It was well-attended and the future sales agents had a high interest in the product, convinced that the lamps would sell well. The agents were able to see that the Natural Light lamp can save their customers money. After two months of use, customers already save money compared to what they would spend on kerosene lamps. Having solar lamps means being independent from the electrical grid,” stated Edius N Makono, Alight Zimbabwe Trust (Plan Zimbabwe Alumni).    Get CleanTechnica’s 1st (completely free) electric car report → “Electric Cars: What Early Adopters & First Followers Want.”   Come attend CleanTechnica’s 1st “Cleantech Revolution Tour” event → in Berlin, Germany, April 9–10.   Keep up to date with all the hottest cleantech news by subscribing to our (free) cleantech newsletter, or keep an eye on sector-specific news by getting our (also free) solar energy newsletter, electric vehicle newsletter, or wind energy newsletter.  

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.

Chaneton E.J.,University of Buenos Aires | Noemi Mazia C.,University of Buenos Aires | Kitzberger T.,National University of Comahue
Journal of Ecology | Year: 2010

Facilitation of recruitment by 'nurse' plants can play a major role in harsh environments. Yet the extent to which consumer-mediated apparent competition from habitat-forming plants may counteract facilitative interactions remains largely unexplored. We examined whether seedling predation by tenebrionid beetles seeking refuge under nurse shrubs may prevent tree recruitment facilitation in a Patagonian steppe-woodland ecotone. Newly emerged seedlings of Austrocedrus chilensis were planted in shrub canopy, off-shrub shelter and bare soil microsites, and monitored for causes of early mortality and for overall survival under ambient and elevated beetle densities. Most seedlings in open microsites died from abiotic stress, whereas shrub cover and artificial shelters decreased desiccation mortality. Herbivory was the main cause of mortality in shrub microsites. Beetle addition increased predation beneath shrubs and in off-shrub shelters, indicating that apparent competition 'spilled over' from shrubs with high insect densities. Litter removal from shrubs prevented seedling predation suggesting that nurse plants altered recruitment by providing food as well as shelter to insects. Herbivory rates did not depend on seedling patch density but decreased with seedling age, with 1-week old plants being most vulnerable to beetle predation. Synthesis. Apparent competition from nurse plants can strongly reduce recruitment facilitation in stressful environments, although weak herbivore density dependence and seedling growth into ontogenetic refuges may limit the strength of apparent competition. An explicit consideration of negative, as well as positive, herbivore-mediated indirect effects from habitat-forming plants would broaden the understanding of community dynamics along stress gradients. © 2010 The Authors. Journal compilation © 2010 British Ecological Society.

Chamon C.,Boston University | Mucciolo E.R.,University of Central Florida | Arrachea L.,University of Buenos Aires | Capaz R.B.,Federal University of Rio de Janeiro
Physical Review Letters | Year: 2011

We propose using a phonon pumping mechanism to transfer heat from a cold to a hot body using a propagating modulation of the medium connecting the two bodies. This phonon pump can cool nanomechanical systems without the need for active feedback. We compute the lowest temperature that this refrigerator can achieve. © 2011 American Physical Society.

Fillottrani P.R.,University of Buenos Aires | Franconi E.,Free University of Bozen Bolzano | Tessaris S.,Free University of Bozen Bolzano
Semantic Web | Year: 2012

ICOM (version 3.0) is an advanced conceptual modelling tool, which allows the user to design multiple extended ontologies. Each project can be organised into several ontologies, with the possibility to include inter- and intra-ontology constraints. Complete logical reasoning is employed by the tool to verify the specification, infer implicit facts, devise stricter constraints, and manifest any inconsistency. ICOM is fully integrated with a very powerful description logic reasoning server which acts as a background inference engine. The intention behind ICOM is to provide a simple conceptual modelling tool that demonstrates the use of, and stimulates interest in, the novel and powerful knowledge representation based technologies for database and ontology design. © 2010 - IOS Press and the authors. All rights reserved.

Vittar N.B.R.,National University of Rio Cuarto | Awruch J.,University of Buenos Aires | Azizuddin K.,Case Western Reserve University | Rivarola V.,National University of Rio Cuarto
International Journal of Biochemistry and Cell Biology | Year: 2010

A new water-soluble phthalocyanine derivative, 2,3,9,10,16,17,23,24-octakis(3-aminopropyloxy) phthalocyaninato zinc II (PoII) was studied as a photosensitizer for photodynamic therapy (PDT) in MCF-7c3 cells. We report here that PoII and red light induces apoptosis. However, the precise mechanism appears to differ from that induced by PDT with other known phthalocyanines. The present study provides evidence that in the case of PoII, caspases do not participate in the apoptotic response. PoII-PDT-treated cells exhibited chromatin condensation and phosphatidylserine (PS) externalization. In the absence of light activation, PoII had no detectable cytotoxic effect. An early event upon PoII-PDT was photodamage to lysosomes, suggesting that they are the primary sites of action. Moreover, the treatment induces Bid activation, mitochondrial swelling and translocation of apoptosis-inducing factor (AIF) to the nucleus. An atypical proteolysis of poly(ADP-ribose) polymerase (PARP) indicative of calpain-like activation was observed. These data support the notion that an alternative mechanism of caspase-independent apoptosis was found in PoII-photosensitized cells. © 2010 Elsevier Ltd.

Garibaldi L.A.,National University of Comahue | Garibaldi L.A.,University of Buenos Aires | Aizen M.A.,National University of Comahue | Klein A.M.,Lüneburg University | And 2 more authors.
Proceedings of the National Academy of Sciences of the United States of America | Year: 2011

Human welfare depends on the amount and stability of agricultural production, as determined by crop yield and cultivated area. Yield increases asymptotically with the resources provided by farmers' inputs and environmentally sensitive ecosystem services. Declining yield growth with increased inputs prompts conversion of more land to cultivation, but at the risk of eroding ecosystem services. To explore the interdependence of agricultural production and its stability on ecosystem services, we present and test a general graphical model, based on Jensen's inequality, of yield-resource relations and consider implications for land conversion. For the case of animal pollination as a resource influencing crop yield, this model predicts that incomplete and variable pollen delivery reduces yield mean and stability (inverse of variability) more for crops with greater dependence on pollinators. Data collected by the Food and Agriculture Organization of the United Nations during 1961-2008 support these predictions. Specifically, crops with greater pollinator dependence had lower mean and stability in relative yield and yield growth, despite global yield increases for most crops. Lower yield growth was compensated by increased land cultivation to enhance production of pollinator-dependent crops. Area stability also decreased with pollinator dependence, as it correlated positively with yield stability among crops. These results reveal that pollen limitation hinders yield growth of pollinator-dependent crops, decreasing temporal stability of global agricultural production, while promoting compensatory land conversion to agriculture. Although we examined crop pollination, our model applies to other ecosystem services for which the benefits to human welfare decelerate as the maximumis approached.

Donnay L.,Solvay Group | Giribet G.,University of Buenos Aires | Giribet G.,Pontifical Catholic University of Valparaíso | Gonzalez H.A.,Solvay Group | Pino M.,University of Santiago de Chile
Physical Review Letters | Year: 2016

We show that the asymptotic symmetries close to nonextremal black hole horizons are generated by an extension of supertranslations. This group is generated by a semidirect sum of Virasoro and Abelian currents. The charges associated with the asymptotic Killing symmetries satisfy the same algebra. When considering the special case of a stationary black hole, the zero mode charges correspond to the angular momentum and the entropy at the horizon. © 2016 American Physical Society.

Blois S.M.,Charité - Medical University of Berlin | Barrientos G.,University of Buenos Aires
Journal of Reproductive Immunology | Year: 2014

Members of the galectin family are expressed within the female reproductive tract and have been shown to be involved in multiple biological functions that support the progression of pregnancy. Specific expression patterns of different members of this family have been identified at the maternal decidua and on the placental side. In some cases, mechanisms by which galectins exert their functions have been delineated in adverse pregnancy outcomes. This review summarizes studies on galectins that have been documented to be important for pregnancy maintenance, either supporting the maternal adaptation to pregnancy or the placentation process. In addition, we focus our discussion on the role of galectins in preeclampsia, a specific life-threatening pregnancy disorder. © 2013 Elsevier Ireland Ltd.

Giribet G.,Solvay Group | Giribet G.,University of Buenos Aires | Giribet G.,Pontifical Catholic University of Valparaíso
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2016

We discuss a Coulomb gas realization of n-point correlation functions in the SL(2,R) Wess-Zumino-Witten (WZW) model that is suitable to compute scattering amplitudes of winding strings in three-dimensional anti-de Sitter space at tree level and one loop. This is a refined version of previously proposed free-field realizations that, among other features, make the H3 + WZW-Liouville correspondence manifest. © 2016 American Physical Society.

Cabral P.D.,Case Western Reserve University | Garvin J.L.,University of Buenos Aires
American Journal of Physiology - Renal Physiology | Year: 2014

Nitric oxide (NO) regulates renal function. Luminal flow stimulates NO production in the thick ascending limb (TAL). Transient receptor potential vanilloid 4 (TRPV4) is amechano-sensitive channel activated by luminal flow in different types of cells. We hypothesized that TRPV4 mediates flow-induced NO production in the rat TAL. We measured NO production in isolated, perfused rat TALs using the fluorescent dye DAF FM. Increasing luminal flow from 0 to 20 nl/min stimulated NO from 8 ± 3 to 45±12 arbitrary units (AU)/min (n = 5; P < 0.05). The TRPV4 antagonists, ruthenium red (15 μmol/l) and RN 1734 (10 μmol/l), blocked flow-induced NO production. Also, luminal flow did not increase NO production in the absence of extracellular calcium. We also studied the effect of luminal flow on NO production in TALs transduced with a TRPV4shRNA. In nontransduced TALs luminal flow increased NO production by 47 ± 17 AU/min (P < 0.05; n = 5). Similar to nontransduced TALs, luminal flow increased NO production by 39 ± 11 AU/min (P < 0.03; n = 5) in TALs transduced with a control negative sequence-shRNA while in TRPV4shRNA-transduced TALs, luminal flow did not increase NO production (Δ10 ± 15 AU/min; n = 5). We then tested the effect of two different TRPV4 agonists on NO production in the absence of luminal flow. 4α-Phorbol 12,13-didecanoate (1 μmol/l) enhanced NO production by 60 ± 11 AU/min (P < 0.002; n = 7) and GSK1016790A (10 ηmol/l) increased NO production by 52 ± 15 AU/min (P < 0.03; n = 5). GSK1016790A (10 ηmol/l) did not stimulate NO production in TRPV4shRNA-transduced TALs. We conclude that activation of TRPV4 channels mediates flow-induced NO production in the rat TAL. © 2014 the American Physiological Society.

Doncic A.,Stanford University | Atay O.,Stanford University | Valk E.,University of Tartu | Grande A.,University of Buenos Aires | And 5 more authors.
Cell | Year: 2015

Cells make accurate decisions in the face of molecular noise and environmental fluctuations by relying not only on present pathway activity, but also on their memory of past signaling dynamics. Once a decision is made, cellular transitions are often rapid and switch-like due to positive feedback loops in the regulatory network. While positive feedback loops are good at promoting switch-like transitions, they are not expected to retain information to inform subsequent decisions. However, this expectation is based on our current understanding of network motifs that accounts for temporal, but not spatial, dynamics. Here, we show how spatial organization of the feedback-driven yeast G1/S switch enables the transmission of memory of past pheromone exposure across this transition. We expect this to be one of many examples where the exquisite spatial organization of the eukaryotic cell enables previously well-characterized network motifs to perform new and unexpected signal processing functions. © 2015 Elsevier Inc.

Castro A.,Harvard University | Dehmami N.,Boston University | Giribet G.,University of Buenos Aires | Kastor D.,University of Massachusetts Amherst
Journal of High Energy Physics | Year: 2013

Black holes are famous for their universal behavior. New thermodynamic relations have been found recently for the product of gravitational entropies over all the horizons of a given stationary black hole. This product has been found to be independent of the mass for all such solutions of Einstein-Maxwell theory in d = 4, 5. We study the universality of this mass independence by introducing a number of possible higher curvature corrections to the gravitational action. We consider finite temperature black holes with both asymptotically flat and (A)dS boundary conditions. Although we find examples for which mass independence of the horizon entropy product continues to hold, we show that the universality of this property fails in general. We also derive further thermodynamic properties of inner horizons, such as the first law and Smarr relation, in the higher curvature theories under consideration, as well as a set of relations between thermodynamic potentials on the inner and outer horizons that follow from the horizon entropy product, whether or not it is mass independent. © 2013 SISSA, Trieste, Italy.

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.

Zold C.L.,University of Buenos Aires | Hussain Shuler M.G.,Johns Hopkins University
Journal of Neuroscience | Year: 2015

The primary visual cortex (V1) is widely regarded as faithfully conveying the physical properties of visual stimuli. Thus, experience induced changes in V1 are often interpreted as improving visual perception (i.e., perceptual learning). Here we describe how, with experience, cue-evoked oscillations emerge in V1 to convey expected reward time as well as to relate experienced reward rate. We show, in chronic multisite local field potential recordings from rat V1, that repeated presentation of visual cues induces the emergence of visually evoked oscillatory activity. Early in training, the visually evoked oscillations relate to the physical parameters of the stimuli. However, with training, the oscillations evolve to relate the time in which those stimuli foretell expected reward. Moreover, the oscillation prevalence reflects the reward rate recently experienced by the animal. Thus, training induces experience-dependent changes in V1 activity that relate to what those stimuli have come to signify behaviorally: when to expect future reward and at what rate. © 2015 the authors.

Barata-Vallejo S.,University of Buenos Aires | Postigo A.,University of Belgrano
Journal of Organic Chemistry | Year: 2010

Figure presented. Perfluoroalkyl-substituted compounds are regarded as important components of fluorophors and for the introduction of fluorous tags into organic substrates. Their syntheses in organic solvents are achieved through different methods, among which, the addition of perfluoroalkyl radicals to unsaturated bonds represents a convenient choice. On the other hand, intermolecular radical reactions in water have attracted the attention of synthetic chemists as a strategic route to carbon-carbon bond formation reactions. In this paper we undertook the intermolecular addition of perfluoroalkyl radicals on electron rich alkenes and alkenes with electron withdrawing groups in water, mediated by silyl radicals, and obtained perfluoroalkyl-substituted compounds in fairly good yields. The radical triggering events employed consist of the thermal decomposition of an azo compound and the dioxygen initiation. Our results indicate that for intermolecular carbon-carbon bond formation reactions mediated by (Me 3Si)3SiH, the decomposition of the azo compound 1,1′-azobis(cyclohexanecarbonitrile) (ACCN) is the best radical initiator. We also found that water exerts a relevant solvent effect on the rates of perfluoroalkyl radical additions onto double bonds and the H atom abstraction from the silane. Our account provides a versatile and convenient method to achieve perfluoroalkylation reactions of alkenes in water to render perfluoroalkylated alkanes as key intermediates in the synthesis of fluorophors and other fluorinated materials. This is the first report where perfluoroalkyl-substituted alkanes are synthesized through intermolecular radical carbon-carbon bond formation reactions in water, mediated by silyl radicals. © 2010 American Chemical Society.

Oliva D.,National University of Quilmes | Tomsic D.,University of Buenos Aires
Journal of Neurophysiology | Year: 2014

Similar to most visual animals, crabs perform proper avoidance responses to objects directly approaching them. The monostratified lobula giant neurons of type 1 (MLG1) of crabs constitute an ensemble of 14–16 bilateral pairs of motion-detecting neurons projecting from the lobula (third optic neuropile) to the midbrain, with receptive fields that are distributed over the extensive visual field of the animal’s eye. Considering the crab Neohelice (previously Chasmagnathus) granulata, here we describe the response of these neurons to looming stimuli that simulate objects approaching the animal on a collision course. We found that the peak firing time of MLG1 acts as an angular threshold detector signaling, with a delay of δ = 35 ms, the time at which an object reaches a fixed angular threshold of 49°. Using in vivo intracellular recordings, we detected the existence of excitatory and inhibitory synaptic currents that shape the neural response. Other functional features identified in the MLG1 neurons were phasic responses at the beginning of the approach, a relation between the stimulus angular velocity and the excitation delay, and a mapping between membrane potential and firing frequency. Using this information, we propose a biophysical model of the mechanisms that regulate the encoding of looming stimuli. Furthermore, we found that the parameter encoded by the MLG1 firing frequency during the approach is the stimulus angular velocity. The proposed model fits the experimental results and predicts the neural response to a qualitatively different stimulus. Based on these and previous results, we propose that the MLG1 neuron system acts as a directional coding system for collision avoidance. © 2014 the American Physiological Society.

Postigo A.,University of Belgrano | Nudelman N.S.,University of Buenos Aires
Journal of Physical Organic Chemistry | Year: 2010

The relevance of radical initiation methodologies for the classical hydrosilylation reactions of organic compounds bearing C-C multiple bonds is due to the need to come up with newer and more efficient methods to effect this reaction, on account of its applications on surface chemistry. In the past, when organic solventswere employed, thermal and photochemical methods for the chain initiation reaction have been documented (thermal and photochemical decompositions of azo compounds). We herein present the dioxygen-initiation technique of the classical radical hydrosilylation reaction of C-C triple bonds with tris(trimethylsilyl)silane ((Me3Si)3SiH) in water. This initiation technique is confronted with the photochemical radical initiation in the absence of a chemical radical precursor other than the silane and also confronted with the classical thermal initiation triggered by the decomposition of an azo compound, both performed in water. The radical-based dioxygen initiation methodology studied in water is shown to afford the highest Z:E stereoselective ratios of hydrosilylated alkenes. Copyright © 2010 John Wiley and Sons, Ltd.

Yahdjian L.,University of Buenos Aires | Sala O.E.,Brown University
Ecosystems | Year: 2010

Arid ecosystems receive precipitation pulses of different sizes that may differentially affect nitrogen (N) losses and N turnover during the growing season. We designed a rainfall manipulation experiment in the Patagonian steppe, southern Argentina, where we simulated different precipitation patterns by adding the same amount of water in evenly spaced three-small rainfall events or in one-single large rainfall event, three times during a growing season. We measured the effect of the size of rainfall pulses on N mineralization and N losses by denitrification, ammonia volatilization, and nitrate and ammonia leaching. Irrigation pulses stimulated N mineralization (P < 0.05), with small and frequent pulses showing higher responses than large pulses (P < 0.10). Irrigation effects were transient and did not result in changes in seasonal net N mineralization suggesting a long-term substrate limitation. Water pulses stimulated gaseous N losses by denitrification, with large pulses showing higher responses than small pulses (P < 0.05), but did not stimulate ammonia volatilization. Nitrate leaching also was higher after large than after small precipitation events (P < 0.05). Small events produced higher N transformations and lower N losses by denitrification and nitrate leaching than large events, which would produce higher N availability for plant growth. Climate change is expected to increase the frequency of extreme precipitation events and the proportion of large to small rainfall events. Our results suggest that these changes would result in reduced N availability and a competitive advantage for deep-rooted species that prefer nitrate over ammonia. Similarly, the ammonium:nitrate ratio might decrease because large events foster nitrate losses but not ammonium losses. © 2010 Springer Science+Business Media, LLC.

Oliva D.,National University of Quilmes | Oliva D.,University of Buenos Aires | Tomsic D.,University of Buenos Aires
Journal of Experimental Biology | Year: 2012

Escape responses to directly approaching predators represent one instance of an animal's ability to avoid collision. Usually, such responses can be easily evoked in the laboratory using two-dimensional computer simulations of approaching objects, known as looming stimuli. Therefore, escape behaviors are considered useful models for the study of computations performed by the brain to efficiently transform visual information into organized motor patterns. The escape response of the crab Neohelice (previously Chasmagnathus) granulata offers an opportunity to investigate the processing of looming stimuli and its transformation into complex motor patterns. Here we studied the escape performance of this crab to a variety of different looming stimuli. The response always consisted of a vigorous run away from the stimulus. However, the moment at which it was initiated, as well as the developed speed, closely matched the expansion dynamics of each particular stimulus. Thus, we analyzed the response events as a function of several variables that could theoretically be used by the crab (angular size, angular velocity, etc.). Our main findings were that: (1) the decision to initiate the escape run is made when the stimulus angular size increases by 7 deg; (2) the escape run is not a ballistic kind of response, as its speed is adjusted concurrently with changes in the optical stimulus variables; and (3) the speed of the escape run can be faithfully described by a phenomenological input-output relationship based on the stimulus angular increment and the angular velocity of the stimulus. © 2012. Published by The Company of Biologists Ltd.

Inigo S.,CONICET | Inigo S.,National University of Quilmes | Alvarez M.J.,Columbia University | Strasser B.,CONICET | And 3 more authors.
Plant Journal | Year: 2012

Two aspects of light are very important for plant development: the length of the light phase or photoperiod and the quality of incoming light. Photoperiod detection allows plants to anticipate the arrival of the next season, whereas light quality, mainly the red to far-red ratio (R:FR), is an early signal of competition by neighbouring plants. phyB represses flowering by antagonising CO at the transcriptional and post-translational levels. A low R:FR decreases active phyB and consequently increases active CO, which in turn activates the expression of FT, the plant florigen. Other phytochromes like phyD and phyE seem to have redundant roles with phyB. PFT1, the MED25 subunit of the plant Mediator complex, has been proposed to act in the light-quality pathway that regulates flowering time downstream of phyB. However, whether PFT1 signals through CO and its specific mechanism are unclear. Here we show that CO-dependent and-independent mechanisms operate downstream of phyB, phyD and phyE to promote flowering, and that PFT1 is equally able to promote flowering by modulating both CO-dependent and-independent pathways. Our data are consistent with the role of PFT1 as an activator of CO transcription, and also of FT transcription, in a CO-independent manner. Our transcriptome analysis is also consistent with CO and FT genes being the most important flowering targets of PFT1. Furthermore, comparison of the pft1 transcriptome with transcriptomes after fungal and herbivore attack strongly suggests that PFT1 acts as a hub, integrating a variety of interdependent environmental stimuli, including light quality and jasmonic acid-dependent defences. © 2011 Blackwell Publishing Ltd.

Kumar S.,University of Buenos Aires | Seidel R.W.,Ruhr University Bochum
Inorganic Chemistry Communications | Year: 2013

Two ligand-bridged bicobaloximes, formed by replacement of pyridine (py) in monocobaloximes, [MeCo(dmgH)2(py)] (Me = methyl, dmgH = dimethylglyoxime) and MeCo(dpgH)2(py) (dpgH = diphenylglyoxime), by 4,4′-bipyridine and 2,4-di(1H-imidazol-1-yl)-6-methoxy-1,3,5-triazine, respectively, are reported. The crystal structures of the ligand-bridged bicobaloximes so obtained are described. © 2012 Elsevier B.V. All rights reserved.

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.

Gantman E.R.,University of Belgrano | Gantman E.R.,University of Buenos Aires
Scientometrics | Year: 2012

This paper examines the influence of economic, linguistic, and political factors in the scientific productivity of countries across selected scientific disciplines. Using a negative binomial regression model, I show that the effect of these determinants is contingent upon the scientific field under analysis. The only variable that exerts a positive and significant effect across all disciplines is the size of the economy. The linguistic variable only has a positive influence in the social sciences as well as in medicine and agricultural sciences. In addition, it is also demonstrated that the degree of political authoritarianism has a negative and statistically significant effect in some of the selected fields. © 2012 Akadémiai Kiadó, Budapest, Hungary.

Baldessari A.,University of Buenos Aires | Iglesias L.E.,National University of Quilmes
Methods in Molecular Biology | Year: 2012

In this article, we describe the application of lipases in acylation and alcoholysis reactions on steroids and nucleosides. In the field of steroids, a variety of acetyl and fatty acid derivatives of androstanes, pregnanes, and cholestanes have been prepared through lipase-catalyzed acylation and alcoholysis reactions taking advantage of the high regio- and stereoselectivity of these enzymes. The substrates as well as the products show a high degree of biological activity as neurosteroids, hormones, and glucocorticoids. The regioselective preparation of diacylated nucleosides by means of an enzymatic alcoholysis allowed the synthesis of nucleosides prodrugs or modified nucleosides. The quantitative full deacylation and dealkoxycarbonylation of nucleosides and steroids is a mild synthetic method for the deprotection of these labile compounds. Some of the reported steroid and nucleoside products are novel, and it is not possible to obtain them satisfactorily by following traditional synthetic procedures. The advantages presented by this methodology, such as selectivity, mild reaction conditions, and low environmental impact, make the lipases an important tool in the application of the principles of Green Chemistry, offering a convenient way to prepare derivatives of natural compounds with a great potential in the pharmaceutical industry. © 2012 Springer Science+Business Media New York.

Barata-Vallejo S.,University of Buenos Aires | Nudelman N.S.,University of Buenos Aires | Postigo A.,University of Belgrano
Current Organic Chemistry | Year: 2011

This account is focused on highlighting the recent advances on synthetically-useful organic reactions employing siliconcentered radicals in water, and presenting new reactions in water, mediated by silyl radicals. In doing so, several types of organic radical transformations will be discussed, such as reduction of organic halides utilizing non toxic organosilane reducing agents in water, transformation of azides into amines, synthesis of protecting silyl ethers in water, hydrosilylation reactions of carbon-carbon double and triple bonds, and radical cyclization reactions in water induced by silicon-centered radicals. More recently, intermolecular radical carboncarbon bond formation reactions mediated by silyl radicals have allowed the synthesis of perfluoroalkyl-substituted compounds in water, widening the scope for the syntheses of fluorophoes. These silicon radical-mediated chain reactions in water are initiated through different methods, among which, thermal, photochemical, and dioxygen initiations are reported to be the most successful methods in water. A versatile aspect of the radical methodology employed in water will be presented in terms of dealing with water-soluble and organic solvent- soluble substrates in these silicon radical-mediated reactions in water. In this regard, for an efficient chain process to take place in water, a chain carrier must be used when water-soluble substrates are employed, whereas organic solvent-soluble materials do not require a chain transporter when silyl radicals are used in water. © 2011 Bentham Science Publishers Ltd.

Agency: European Commission | Branch: FP7 | Program: CP-SICA | Phase: HEALTH-2007-2.3.2-12 | Award Amount: 1.54M | Year: 2008

Tuberculosis is today amongst the major worldwide health threats. Treatment failure is unfortunately becoming more usual, especially in countries lacking the long and costly treatment adapted to patients. Thus, tuberculosis causes 2 million deaths every year and latently persists in over 1 billion individuals worldwide. Current treatments are challenged by multidrug resistant strains, drug side effects, and co-infections. Therefore, identification of potent, safety antimycobacterial agents is mandatory. However, the success of this strategy is largely determined by the detailed knowledge of their mechanism of action, which in turn depends on the validation of suitable biological targets. This project pursues the definition of new, complementary therapeutic approaches by identifying the molecular basis of the nitrosative stress resistance of M. tuberculosis. Our working hypothesis is that a decrease in the NO resistance of the microorganism should reduce significantly the capability to rest in latency, thus contributing to increase the efficacy of the therapeutic treatment. In this context, understanding of the NO detoxification activity played by M. tuberculosis trHbN is essential. Accordingly, our objectives are i) to unravel the molecular mechanism underlying the NO dioxygenase activity of M. tuberculosis trHbN, ii) to establish the structure-function relationships in trHbN and trHbO from M. tuberculosis, and iii) to identify the reductase protein system that helps trHbN to restore the ferrous state required to initiate the NO detoxification cycle. The outcome of the project should provide a firm basis to assess the viability of trHbN as a therapeutic target, and set up the background to exploit this knowledge in the design of innovative therapeutic strategies to fight the disease.

Goldman C.G.,University of Buenos Aires | Mitchell H.M.,University of New South Wales
Helicobacter | Year: 2010

Over the last 12 months, new insights into the association of non-Helicobacter pylori Helicobacters with a range of human diseases in children and adults, including hepatobiliary disease, Crohn's disease, sepsis, and gastric disease were published. Studies investigating the presence of non-H. pylori Helicobacters in domestic animals reinforce previous findings that cats and dogs harbor gastric Helicobacter species and thus may be an important source of these organisms in humans. The confounding effect of enterohepatic Helicobacters on the outcome of biomedical research was investigated in several studies and led to recommendations that animals should be screened prior to performing experiments. A number of important and novel investigations regarding pathogenic mechanisms and immune responses to enterohepatic Helicobacters were conducted. Genomic advances in non-H. pylori Helicobacters included description of the complete genome of Helicobacter canadensis, delineation of two Helicobacter bilis genomospecies, and identification of a novel cis-regulatory RNA. New insights concerning growth conditions, biochemical characterization, and the effect of certain dietary compounds on Helicobacter spp. have also been reported. © 2010 Blackwell Publishing Ltd.

Coronado E.A.,National University of Cordoba | Encina E.R.,National University of Cordoba | Stefani F.D.,University of Buenos Aires
Nanoscale | Year: 2011

We present to a general readership an overview of the rich variety of phenomena and applications that arise from the interaction of metallic nanoparticles with light. First, we present the fundamental physics of localized surface plasmon resonances, the most relevant theories and numerical methods, as well as optical detection schemes. Finally, we explain how the localized surface plasmon resonances are currently exploited for the nanoscale manipulation of light, heat and forces in various applications and experimental investigations. © 2011 The Royal Society of Chemistry.

Alvarez O.,National University of San Juan | Gimenez M.,National University of San Juan | Braitenberg C.,University of Trieste | Folguera A.,University of Buenos Aires
Geophysical Journal International | Year: 2012

Global gravity field models, derived from satellite measurements integrated with terrestrial observations, provide a model of the Earth's gravity field with high spatial resolution and accuracy. The Earth Gravity Model EGM08, a spherical harmonic expansion of the geopotential up to degree and order 2159, has been used to calculate two functionals of the geopotential: the gravity anomaly and the vertical gravity gradient applied to the South Central Andes area. The satellite-only field of the highest resolution has been developed with the observations of satellite GOCE, up to degree and order 250. The topographic effect, a fundamental quantity for the downward continuation and validation of satellite gravity gradiometry data, was calculated from a digital elevation model which was converted into a set of tesseroids. This data is used to calculate the anomalous potential and vertical gravity gradient. In the Southern Central Andes region the geological structures are very complex, but not well resolved. The processing and interpreting of the gravity anomaly and vertical gradients allow the comparison with geological maps and known tectonic structures. Using this as a basis, a few features can be clearly depicted as the contact between Pacific oceanic crust and the Andean fold and thrust belt, the seamount chains over the Oceanic Nazca Plate, and the Famatinian and Pampean Ranges. Moreover the contact between the Rio de la Plata craton and the Pampia Terrain is of great interest, since it represents a boundary that has not been clearly defined until now. Another great lineament, the Valle Fertil-Desaguadero mega-lineament, an expression of the contact between Cuyania and Pampia terranes, can also be clearly depicted. The authors attempt to demonstrate that the new gravity fields can be used for identifying geological features, and therefore serve as useful innovative tools in geophysical exploration. © 2012 The Authors Geophysical Journal International © 2012 RAS.

De Fazio E.,University of Buenos Aires | Bercoff P.G.,National University of Cordoba | Jacobo S.E.,University of Buenos Aires
Journal of Magnetism and Magnetic Materials | Year: 2011

Polycrystalline manganese-zinc ferrite with lithium substitution of composition Li0.5xMn0.4Zn0.6-xFe 20.5xO4 (0.0≤x≤0.4) was prepared by the usual ceramic method. X-ray diffraction analysis confirmed that the samples have a spinel structure and are of single phase for some values of Li content. Lithium doping considerably modifies saturation magnetization since its value increases from 57.5 emu/g for x=0.0 to 82.9 emu/g for x=0.4. Lithium inclusion increases the real permeability (over 1 MHz) while the natural resonance frequency shifts to lower values as the fraction of Li increases. These ferrites show good electromagnetic properties as absorbers in the microwave range of 1 MHz 1 GHz. © 2011 Elsevier B.V. All rights reserved.

De San Martin J.Z.,Institute Investigaciones en Ingenieria Genetica Biologia Molecular | Pyott S.,University of North Carolina at Wilmington | Ballestero J.,Institute Investigaciones en Ingenieria Genetica Biologia Molecular | Katz E.,Institute Investigaciones en Ingenieria Genetica Biologia Molecular | Katz E.,University of Buenos Aires
Journal of Neuroscience | Year: 2010

In the mammalian auditory system, the synapse between efferent olivocochlear (OC) neurons and sensory cochlear hair cells is cholinergic, fast, and inhibitory. This efferent synapse is mediated by the nicotinic α9α10 receptor coupled to the activation of SK2 Ca 2+-activated K+ channels that hyperpolarize the cell. So far, the ion channels that support and/or modulate neurotransmitter release from the OC terminals remain unknown. To identify these channels, we used an isolated mouse cochlear preparation and monitored transmitter release from the efferent synaptic terminals in inner hair cells (IHCs) voltage clamped in the whole-cell recording configuration. Acetylcholine (ACh) release was evoked by electrically stimulating the efferent fibers that make axosomatic contacts with IHCs before the onset of hearing. Using the specific antagonists for P/Q- and N-type voltage-gated calcium channels (VGCCs), ω-agatoxin IVA and ω-conotoxin GVIA, respectively, we show that Ca2+ entering through both types of VGCCs support the release process at this synapse. Interestingly, we found that Ca2+ entering through the dihydropiridine-sensitive L-type VGCCs exerts a negative control on transmitter release. Moreover, using immunostaining techniques combined with electrophysiology and pharmacology, we show that BK Ca2+-activated K+ channels are transiently expressed at the OC efferent terminals contacting IHCs and that their activity modulates the release process at this synapse. The effects of dihydropiridines combined with iberiotoxin, a specific BK channel antagonist, strongly suggest that L-type VGCCs negatively regulate the release of ACh by fueling BK channels that are known to curtail the duration of the terminal action potential in several types of neurons. Copyright © 2010 the authors.

Becher E.F.,University of Buenos Aires | McVary K.T.,University of Illinois at Springfield
Sexual Medicine Reviews | Year: 2014

Introduction: Lower urinary tract symptoms (LUTS) because of benign prostatic hyperplasia (BPH) are a highly prevalent condition in men over 50 years old, and their incidence increases with age. The relationship between LUTS and erectile dysfunction (ED) has received increased attention recently because both diseases are highly prevalent, frequently co-associated in the same aging male group, and contribute significantly to the overall quality of life. In this review, we will examine the literature to assess the impact of surgical and minimally invasive treatments for LUTS/BPH on the male's sexual health. Methods: The impact of the various surgical and minimally invasive treatments for LUTS/BPH was reviewed to ascertain the impact on erectile and ejaculatory function. Results: Sexual side effects of treatment for LUTS/BPH are underappreciated by urologists but likely play a prominent role in patient decision making, creating a disparity between provider and patient. Almost all accepted therapies for LUTS (surgical or medical) can affect some aspect of sexual health, making it imperative that health-care professionals understand their patients' concerns and motivations in these two linked diseases. The incidence of newly diagnosed postoperative ED in patients treated with monopolar transurethral resection (TURP) is around 14%, with reported values in various studies ranging from 0-32.5%, 7.7%, 6.5%, 17%, to 14%. Importantly, there is no significant difference reported between bipolar and monopolar TURP on sexual function. Conclusion: The risk of sexual side effects is an important one to consider in discussing the implications for any LUTS intervention as they play a prominent role in patient motivation, acceptance of bother and decision making concerning surgical intervention, thus creating a potential disparity between provider and patient. Becher EF and McVary KT. Surgical procedures for BPH/LUTS: Impact on male sexual health. Sex Med Rev 2014;2:47-55. © 2013 International Society for Sexual Medicine.

Austin A.T.,University of Buenos Aires | Zanne A.E.,George Washington University
Journal of Ecology | Year: 2015

Plants have numerous impacts on biogeochemical cycling across both aquatic and terrestrial ecosystems. These effects extend well beyond the critical role of carbon (C) fixation through photosynthesis that provides the basis for ecosystem energy flow. While foliar and root traits of senescent plant material (litter) have been explored in detail in terrestrial ecosystems, there is a resurgence of interest in how plants modulate biogeochemical cycling in ways other than litter quality effects on C and nutrient mineralization. This Special Feature represents a collection of 'fresh' perspectives on how plants alone, or in interaction with other organisms, have important and lasting impacts on biogeochemical cycles of C and nutrients in a range of terrestrial and aquatic environments. We begin in the open ocean and then peer from the forest edge before moving into forest understoreys and grasslands to examine the control by live terrestrial plants on ecosystem C and nutrient cycling. Plants directly affect biogeochemical cycling while living through their diversity and composition, nutrient capture and strategies for assimilating C, and by altering the microclimate for decomposition. In addition, how they construct their tissues and alter the abiotic environment has large impacts on the turnover of C and nutrients once plants have senesced or died. From the direct impact of plants, we move onto the influence of plant-insect interactions, which effectively determine changes in plant stoichiometry in grasslands of varying diversity. Finally, looking directly in the soil, it is clear that plant-mycorrhizae interactions are important in modulating the response of litter decomposition to nutrient addition and the nature of C metabolism in the soil. Synthesis. The papers here highlight careful matching between how plants live and their biotic and abiotic contexts. Taken together, it appears that the dynamic, rather than passive, nature of plant responses to variable environments is key in affecting ecosystem level processes of C and nutrient turnover. This Special Feature highlights a diversity of connections between plants and their environment and demonstrates that in both life and death, how plants respond to these changes differs among plant lineages and this diversity will play a central role in determining biogeochemical cycling in the future in aquatic and terrestrial ecosystems. © 2015 British Ecological Society.

Sanders J.,TU Eindhoven | Jonckheere M.,University of Buenos Aires | Kokkelmans S.,TU Eindhoven
Physical Review Letters | Year: 2015

Several recent experiments have established by measuring the Mandel Q parameter that the number of Rydberg excitations in ultracold gases exhibits sub-Poissonian statistics. This effect is attributed to the Rydberg blockade that occurs due to the strong interatomic interactions between highly excited atoms. Because of this blockade effect, the system can end up in a state in which all particles are either excited or blocked: a jamming limit. We analyze appropriately constructed random-graph models that capture the blockade effect, and derive formulae for the mean and variance of the number of Rydberg excitations in jamming limits. This yields an explicit relationship between the Mandel Q parameter and the blockade effect, and comparison to measurement data shows strong agreement between theory and experiment. © 2015 American Physical Society.

Teitelbaum T.,University of Buenos Aires | Mininni P.D.,U.S. National Center for Atmospheric Research
Physics of Fluids | Year: 2011

We present a parametric space study of the decay of turbulence in rotating flows combining direct numerical simulations, large eddy simulations, and phenomenological theory. Several cases are considered: (1) the effect of varying the characteristic scale of the initial conditions when compared with the size of the box, to mimic "bounded" and "unbounded" flows; (2) the effect of helicity (correlation between the velocity and vorticity); (3) the effect of Rossby and Reynolds numbers; and (4) the effect of anisotropy in the initial conditions. Initial conditions include the Taylor-Green vortex, the Arn'old-Beltrami-Childress flow, and random flows with large-scale energy spectrum proportional to k4. The decay laws obtained in the simulations for the energy, helicity, and enstrophy in each case can be explained with phenomenological arguments that consider separate decays for two-dimensional and three-dimensional modes and that take into account the role of helicity and rotation in slowing down the energy decay. The time evolution of the energy spectrum and development of anisotropies in the simulations are also discussed. Finally, the effect of rotation and helicity in the skewness and kurtosis of the flow is considered. © 2011 American Institute of Physics.

Gabelloni M.L.,Institute Medicina Experimental IMEX | Trevani A.S.,Institute Medicina Experimental IMEX | Sabatte J.,University of Buenos Aires | Geffner J.,University of Buenos Aires
Seminars in Immunopathology | Year: 2013

Neutrophils not only play a critical role as a first line of defense against bacteria and fungi infections but also contribute to tissue injury associated with autoimmune and inflammatory diseases. Neutrophils are rapidly and massively recruited from the circulation into injured tissues displaying an impressive arsenal of toxic weapons. Although effective in their ability to kill pathogens, these weapons were equally effective to induce tissue damage. Therefore, the inflammatory activity of neutrophils must be regulated with exquisite precision and timing, a task mainly achieved through a complex network of mechanisms, which regulate neutrophil survival. Neutrophils have the shortest lifespan among leukocytes and usually die via apoptosis although new forms of cell death have been characterized over the last few years. The lifespan of neutrophils can be dramatically modulated by a large variety of agents such as cytokines, pathogens, danger-associated molecular patterns as well as by pharmacological manipulation. Recent findings shed light about the complex mechanisms responsible for the regulation of neutrophil survival in different physiological, pathological, and pharmacological scenarios. Here, we provide an updated review on the current knowledge and new findings in this field and discuss novel strategies that could be used to drive the resolution of neutrophil-mediated inflammatory diseases. © 2013 Springer-Verlag Berlin Heidelberg.

Spagnuolo C.M.,National University of Tucuman | Rapalini A.E.,University of Buenos Aires | Astini R.A.,National University of Cordoba
Gondwana Research | Year: 2012

Different hypotheses have been proposed to account for the geologic evolution of the southwestern margin of Gondwana in the Early Paleozoic, involving accretion and displacement of different terranes in a protracted convergent margin. In order to constrain and understand the kinematic and paleogeographic evolution of the Pampia terrane a paleomagnetic study was carried out in different Cambrian to Devonian units of the Eastern Cordillera (Cordillera Oriental) and the Interandean Zone (Interandino) of NW Argentina. Paleomagnetic poles from the Campanario Formation (Middle to Upper Cambrian): 1.5°N 1.9°E A 95=9.2° K=37.46N=8; and Santa Rosita Formation (Lower Ordovician): 8.6°N 355.3°E A 95=10.1° K=26.78 n=9, representative of the Pampia terrane, are interpreted to indicate a Late Cambrian significant displacement with respect to the Río de la Plata and other Gondwana cratons. A model, compatible with several geological evidences that explains this displacement in the framework of the final stages of Gondwana assembly is presented. We propose a simple dextral strike-slip kinematic model in which Pampia and Antofalla (-Arequipa?) blocks moved during Late Cambrian times from a position at the present southern border of the Kalahari craton into its final position next to the Rio de la Plata craton by the Early Ordovician. © 2011 International Association for Gondwana Research.

The southwestern Gondwana basement block configuration in the central Argentinean offshore area was analyzed using gravimetric, magnetic and seismic data and existing onshore tectonic models. The resultant maps, the distribution of the Mesozoic and Cenozoic basins and Paleozoic structural features were used to validate the interpretations and to produce a new regional tectonic model. Pre-Carboniferous southwestern Gondwana of South America was interpreted as an open margin formed from east to west by the Dom Feliciano Belt, the Río de la Plata Craton, the Pampean Belt and the Pampia and Cuyania terranes. The collision of the Patagonia allochthonous terrane during the Late Paleozoic resulted in the development of the Ventania-Cape Fold Belt, which was mapped for the first time off the Argentinean coast out to 600 km from the shore. A strong change in the orientation of the Fold Belt is referred to as the Colorado Syntaxis, a mirror image of the Cape Syntaxis in South Africa. This change reflects the buttressing effect of the cratonic blocks that hamper the northward propagation of syncollisional deformation and resulted in a 180-km shift of the orogenic front. The Mesozoic basins and the basement block distribution were analyzed. The Pampean Belt, a deformed area produced by the Pampia accretion to the cratonic area, is the locus to two episutural basins, the General Levalle and Macachín basins. The Salado Basin was interpreted as an episutural basin controlled by a 2.1-2.0 Ga suture within the Rio de la Plata Craton. The Colorado Basin is composed of four segmented depocenters that reflect different emplacement controls: the location of the western Colorado Basin was controlled by the Upper Paleozoic orogen; the distributions of the central and eastern Colorado depocenters, orthogonal to the continental boundary, were also strongly influenced by the Upper Paleozoic structures and were offset by lineaments that reflect Dom Feliciano fabric; the Colorado Basin external depocenter that parallels the continental margin was also controlled by these lineaments. We interpret a time gap of some 50 Ma between the beginning of the evolution of the margin-orthogonal depocenters and the Atlantic breakup. © 2012 Elsevier Ltd.

Jacobo S.E.,University of Buenos Aires | Herme C.,University of Buenos Aires | Bercoff P.G.,National University of Cordoba
Journal of Alloys and Compounds | Year: 2010

Strontium hexaferrite samples of different composition were prepared by the self-combustion method and heat-treated in air at 1100 °C for 2 h: SrFe 12O 19 (S0), Sr 0.7Nd 0.3Fe 11.7Co 0.3O 19 (SS), Sr 0.7Nd 0.3Fe 10.7Co 0.3O 19 (SM) and Sr 0.7Nd 0.3Fe 8.4Co 0.3O 19 (SL). The phase identification of the powders was performed using XRD. Only sample SL (with the lowest iron concentration) shows well-defined peaks of the hexaferrite phase with no secondary phases. Nd-Co substitution modifies saturation magnetization (M S) and coercivity (H c) but only samples with low Fe 3+ content (SL and SM) show the best magnetic properties, indicating that the best results for applications of this ferrite will be obtained with an iron deficiency in the stoichiometric formulation. © 2009 Elsevier B.V. All rights reserved.

Galante J.,University of Cardiff | Galante I.,University of Buenos Aires | Bekkers M.-J.,TIME Higher School | Gallacher J.,University of Cardiff
Journal of Consulting and Clinical Psychology | Year: 2014

Objective: Kindness-based meditation (KBM) is a rubric covering meditation techniques developed to elicit kindness in a conscious way. Some techniques, for example, loving-kindness meditation and compassion meditation, have been included in programs aimed at improving health and well-being. Our aim was to systematically review and meta-analyze the evidence available from randomized controlled trials (RCTs) comparing the effects of KBM on health and well-being against passive and active control groups in patients and the general population. Method: Searches were completed in March 2013. Two reviewers applied predetermined eligibility criteria (RCTs, peer-reviewed publications, theses or conference proceedings, adult participants, KBM interventions) and extracted the data. Meta-analyses used random-effects models. Results: Twenty-two studies were included. KBM was moderately effective in decreasing self-reported depression (standard mean difference [Hedges's g] = -0.61, 95% confidence interval [CI] [-1.08, -0.14]) and increasing mindfulness (Hedges's g = 0.63, 95% CI [0.22, 1.05]), compassion (Hedges's g = 0.61, 95% CI [0.24, 0.99]) and self-compassion (Hedges's g = 0.45, 95% CI [0.15, 0.75]) against passive controls. Positive emotions were increased (Hedges's g = 0.42, 95% CI [0.10, 0.75]) against progressive relaxation. Exposure to KBM may initially be challenging for some people. Results were inconclusive for some outcomes, in particular against active controls. The methodological quality of the reports was low to moderate. Results suffered from imprecision due to wide CIs deriving from small studies. Conclusions: KBM showed evidence of benefits for the health of individuals and communities through its effects on well-being and social interaction. Further research including well-conducted large RCTs is warranted. © 2014 American Psychological Association.

Storer C.L.,University of Texas at El Paso | Dickey C.A.,University of South Florida | Galigniana M.D.,University of Buenos Aires | Rein T.,Max Planck Institute of Psychiatry | Cox M.B.,University of Texas at El Paso
Trends in Endocrinology and Metabolism | Year: 2011

FKBP51 and FKBP52 are diverse regulators of steroid hormone receptor signaling, including receptor maturation, hormone binding and nuclear translocation. Although structurally similar, they are functionally divergent, which is largely attributed to differences in the FK1 domain and the proline-rich loop. FKBP51 and FKBP52 have emerged as likely contributors to a variety of hormone-dependent diseases, including stress-related diseases, immune function, reproductive functions and a variety of cancers. In addition, recent studies have implicated FKBP51 and FKBP52 in Alzheimer's disease and other protein aggregation disorders. This review summarizes our current understanding of FKBP51 and FKBP52 interactions within the receptor-chaperone complex, their contributions to health and disease, and their potential as therapeutic targets for the treatment of thesediseases. © 2011 Elsevier Ltd.

Gianelli V.R.,Instituto Nacional de Tecnologia Agropecuaria | Bedmar F.,University of Buenos Aires | Costa J.L.,Instituto Nacional de Tecnologia Agropecuaria
Environmental Toxicology and Chemistry | Year: 2014

Imazapyr is a herbicide widely used for weed control in imidazolinone-tolerant sunflower. Imazapyr has a high potential for leaching into groundwater because it is highly water-soluble, persistent in soil, and only weakly sorbed by soils. There is a lack of information available in Argentina concerning groundwater leaching of imazapyr. Therefore, the objective of the present study was to determine the persistence and sorption of imazapyr in 3 Argentinean soils (Tandil, Anguil, and Cerro Azul sites). The presence and concentration of imazapyr were determined and quantified by ultra-performance liquid chromatography and tandem mass spectrometry. The persistence in soils followed the order: Cerro Azul>Tandil>Anguil, with half-life values of 121 d, 75 d, and 37 d, respectively. The half-life of imazapyr was negatively associated with soil pH and iron and aluminum content, and was positively related to clay content. Imazapyr sorption was found to be well described by the Freundlich isotherm. Soil pH and clay, iron, and aluminum contents were the main factors affecting the sorption of imazapyr. The sorption had a limiting effect on the degradation rate. Under certain conditions, the weak sorption and high persistence may increase the movement of imazapyr in the soil profile and the risk of groundwater pollution. © 2013 SETAC.

Easdale M.H.,Instituto Nacional de Tecnologia Agropecuaria | Aguiar M.R.,University of Buenos Aires
Journal of Arid Environments | Year: 2012

Many of the complex issues worldwide regarding environmental management and sustainable develo-pment require integrating the social and natural sciences. Nevertheless, while theoretical discussions have been increasingly developed, operative issues are still major barriers to integrated social-ecological analysis. The aim of this paper was to assess regional forage production in semi-arid rangelands as a key feature in social-ecological analysis, by using human organizational units (i.e. counties). We used these state-administrative units to explore demographic and farming indicators in order to address socio-productive implications of different regional forage production dynamics. We studied the forage spatial and temporal dynamics in two different large ecological regions: Monte and Patagonia, under a single administrative unit (i.e. province). Since forage production estimations in arid rangelands are not trivial, we tested two different methods. We found that inter-annual variability in forage production explained the main differences between regions. At a regional level, zones with higher temporal variability in forage production registered less rural residents and farm numbers, but inverse situations were registered at sub-regional scales. We found a non-linear relationship between forage production variability and rural population density. We proposed differentiated policy recommendations regarding rangeland management and animal husbandry, considering both the social and ecological contexts. © 2012 Elsevier Ltd.

Eclesia R.P.,Instituto Nacional de Tecnologia Agropecuaria | Eclesia R.P.,University of Buenos Aires | Jobbagy E.G.,National University of San Luis | Jackson R.B.,Duke University | And 2 more authors.
Global Change Biology | Year: 2012

The replacement of native vegetation by pastures or tree plantations is increasing worldwide. Contradictory effects of these land use transitions on the direction of changes in soil organic carbon (SOC) stocks, quality, and vertical distribution have been reported, which could be explained by the characteristics of the new or prior vegetation, time since vegetation replacement, and environmental conditions. We used a series of paired-field experiments and a literature synthesis to evaluate how these factors affect SOC contents in transitions between tree- and grass-dominated (grazed) ecosystems in South America. Both our field and literature approaches showed that SOC changes (0-20 cm of depth) were independent of the initial native vegetation (forest, grassland, or savanna) but strongly dependent on the characteristics of the new vegetation (tree plantations or pastures), its age, and precipitation. Pasture establishment increased SOC contents across all our precipitation gradient and C gains were greater as pastures aged. In contrast, tree plantations increased SOC stocks in arid sites but decreased them in humid ones. However, SOC losses in humid sites were counterbalanced by the effect of plantation age, as plantations increased their SOC stocks as plantations aged. A multiple regression model including age and precipitation explained more than 50% (p < 0.01) of SOC changes observed after sowing pastures or planting trees. The only clear shift observed in the vertical distribution of SOC occurred when pastures replaced native forests, with SOC gains in the surface soil but losses at greater depths. The changes in SOC stocks occurred mainly in the silt+clay soil size fraction (MAOM), while SOC stocks in labile (POM) fraction remained relatively constant. Our results can be considered in designing strategies to increase SOC storage and soil fertility and highlight the importance of precipitation, soil depth, and age in determining SOC changes across a range of environments and land-use transitions. © 2012 Blackwell Publishing Ltd.

Schaber J.,Otto Von Guericke University of Magdeburg | Baltanas R.,University of Buenos Aires | Bush A.,University of Buenos Aires | Klipp E.,Humboldt University of Berlin | Colman-Lerner A.,University of Buenos Aires
Molecular Systems Biology | Year: 2012

The high osmolarity glycerol (HOG) pathway in yeast serves as a prototype signalling system for eukaryotes. We used an unprecedented amount of data to parameterise 192 models capturing different hypotheses about molecular mechanisms underlying osmo-adaptation and selected a best approximating model. This model implied novel mechanisms regulating osmo-adaptation in yeast. The model suggested that (i) the main mechanism for osmo-adaptation is a fast and transient non-transcriptional Hog1-mediated activation of glycerol production, (ii) the transcriptional response serves to maintain an increased steady-state glycerol production with low steady-state Hog1 activity, and (iii) fast negative feedbacks of activated Hog1 on upstream signalling branches serves to stabilise adaptation response. The best approximating model also indicated that homoeostatic adaptive systems with two parallel redundant signalling branches show a more robust and faster response than single-branch systems. We corroborated this notion to a large extent by dedicated measurements of volume recovery in single cells. Our study also demonstrates that systematically testing a model ensemble against data has the potential to achieve a better and unbiased understanding of molecular mechanisms. © 2012 EMBO and Macmillan Publishers Limited.

Gonzalez Solveyra E.,University of Buenos Aires | De La Llave E.,University of Buenos Aires | Scherlis D.A.,University of Buenos Aires | Molinero V.,University of Utah
Journal of Physical Chemistry B | Year: 2011

We investigate the melting and formation of ice in partially filled hydrophilic and hydrophobic nanopores of 3 nm diameter using molecular dynamics simulations with the mW water model. Above the melting temperature, the partially filled nanopores contain two water phases in coexistence: a condensed liquid plug and a surface-adsorbed phase. It has been long debated in the literature whether the surface-adsorbed phase is involved in the crystallization. We find that only the liquid plug crystallizes on cooling, producing ice I with stacks of hexagonal and cubic layers. The confined ice is wetted by a premelted liquid layer that persists in equilibrium with ice down to temperatures well below its melting point. The liquid-ice transition is first-order-like but rounded. We determine the temperature and enthalpy of melting as a function of the filling fraction of the pore. In agreement with experiments, we find that the melting temperature of the nanoconfined ice is strongly depressed with respect to the bulk Tm, it depends weakly on the filling fraction and is insensitive to the hydrophobicity of the pore wall. The state of water in the crystallized hydrophilic and hydrophobic pores, however, is not the same: the hydrophobic pore has a negligible density of the surface-adsorbed phase and higher fraction of water in the ice phase than the hydrophilic pore. The widths of the ice cores are nevertheless comparable for the hydrophobic and hydrophilic pores, and this may explain their almost identical melting temperatures. The enthalpy of melting ΔHm, when normalized by the actual amount of ice in the pore, is indistinguishable for the hydrophobic and hydrophilic pores, insensitive to the filling fraction, and within the error bars, the same as the difference in enthalpy between bulk liquid and bulk ice evaluated at the temperature of melting of ice in the nanopores. © 2011 American Chemical Society.

Mietta J.L.,University of Buenos Aires | Jorge G.,National University of General Sarmiento | Martin Negri R.,University of Buenos Aires
Smart Materials and Structures | Year: 2014

A flexible, anisotropic and portable stress sensor (logarithmic reversible response between 40-350 kPa) was fabricated, in which i) the sensing material, ii) the electrical contacts and iii) the encapsulating material, were based on polydimethylsiloxane (PDMS) composites. The sensing material is a slide of an anisotropic magnetorheological elastomer (MRE), formed by dispersing silver-covered magnetite particles (Fe3O4@Ag) in PDMS and by curing in the presence of a uniform magnetic field. Thus, the MRE is a structure of electrically conducting pseudo-chains (needles) aligned in a specific direction, in which electrical conductivity increases when stress is exclusively applied in the direction of the needles. Electrical conductivity appears only between contact points that face each other at both sides of the MRE slide. An array of electrical contacts was implemented based on PDMS-silver paint metallic composites. The array was encapsulated with PDMS. Using Fe 3O4 superparamagnetic nanoparticles also opens up possibilities for a magnetic field sensor, due to the magnetoresistance effects. © 2014 IOP Publishing Ltd.

Uriu K.,RIKEN | Morelli L.G.,University of Buenos Aires | Morelli L.G.,CONICET | Oates A.C.,UK National Institute for Medical Research | Oates A.C.,University College London
Seminars in Cell and Developmental Biology | Year: 2014

Cell movement and local intercellular signaling are crucial components of morphogenesis during animal development. Intercellular signaling regulates the collective movement of a cell population via direct cell-cell contact. Cell movement, conversely, can influence local intercellular signaling by rearranging neighboring cells. Here, we first discuss theoretical models that address how intercellular signaling regulates collective cell movement during development. Examples include neural crest cell migration, convergent extension, and cell movement during vertebrate axis elongation. Second, we review theoretical studies on how cell movement may affect intercellular signaling, using the segmentation clock in zebrafish as an example. We propose that interplay between cell movement and intercellular signaling must be considered when studying morphogenesis in embryonic development. © 2014 Elsevier Ltd.

Navarro A.,University of Cádiz | Boveris A.,University of Buenos Aires
Frontiers in Aging Neuroscience | Year: 2010

Brain senescence and neurodegeneration occur with a mitochondrial dysfunction characterized by impaired electron transfer and by oxidative damage. Brain mitochondria of old animals show decreased rates of electron transfer in complexes I and IV, decreased membrane potential, increased content of the oxidation products of phospholipids and proteins and increased size and fragility. This impairment, with complex I inactivation and oxidative damage, is named "complex I syndrome" and is recognized as characteristic of mammalian brain aging and of neurodegenerative diseases. Mitochondrial dysfunction is more marked in brain areas as rat hippocampus and frontal cortex, in human cortex in Parkinson's disease and dementia with Lewy bodies, and in substantia nigra in Parkinson's disease. The molecular mechanisms involved in complex I inactivation include the synergistic inactivations produced by ONOO- mediated reactions, by reactions with free radical intermediates of lipid peroxidation and by amine-aldehyde adduction reactions. The accumulation of oxidation products prompts the idea of antioxidant therapies. High doses of vitamin E produce a significant protection of complex I activity and mitochondrial function in rats and mice, and with improvement of neurological functions and increased median life span in mice. Mitochondria-targeted antioxidants, as the Skulachev cations covalently attached to vitamin E, ubiquinone and PBN and the SS tetrapeptides, are negatively charged and accumulate in mitochondria where they exert their antioxidant effects. Activation of the cellular mechanisms that regulate mitochondrial biogenesis is another potential therapeutic strategy, since the process generates organelles devoid of oxidation products and with full enzymatic activity and capacity for ATP production. © 2010 Navarro and Boveris.

Coluccio Leskow E.,University of Buenos Aires | Martin T.A.W.,TRIUMF Laboratory Particle and Nuclear Physics | de la Puente A.,TRIUMF Laboratory Particle and Nuclear Physics
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2015

We study a minimal extension to the Standard Model with an additional real scalar triplet, σ, and a single vector-like quark, T. This class of models appear naturally in extensions of the Littlest Higgs model that incorporate dark matter without the need of T-parity. We assume the limit that the triplet does not develop a vacuum expectation value and that all dimension five operators coupling the triplet to Standard Model fields and the vector-like quarks are characterized by the scale Λ at which we expect new physics to arise. We introduce new non-renormalizable interactions between the new scalar sector and fermion sector that allow mixing between the Standard Model third generation up-type quark and the vector-like quark in a way that leads to the cancellation of the leading quadratic divergences to the one-loop corrections from the top quark to the mass of the Higgs boson. Within this framework, new decay modes of the vector-like quark to the real scalar triplet and SM particles arise and bring forth an opportunity to probe this model with existing and future LHC data. We contrast constraints from direct colliders searches with low energy precision measurements and find that heavy vector-like top quarks with a mass as low as 650 GeV are consistent with current experimental constraints in models where new physics arises at scales below 2 TeV. © 2015 The Authors.

Mendez J.M.,University of Utah | Mindlin G.B.,University of Buenos Aires | Goller F.,University of Utah
Journal of Neurophysiology | Year: 2012

The mechanisms by which telencephalic areas affect motor activities are largely unknown. They could either take over motor control from downstream motor circuits or interact with the intrinsic dynamics of these circuits. Both models have been proposed for telencephalic control of respiration during learned vocal behavior in birds. The interactive model postulates that simple signals from the telencephalic song control areas are sufficient to drive the nonlinear respiratory network into producing complex temporal sequences. We tested this basic assumption by electrically stimulating telencephalic song control areas and analyzing the resulting respiratory patterns in zebra finches and in canaries. We found strong evidence for interaction between the rhythm of stimulation and the intrinsic respiratory rhythm, including naturally emerging subharmonic behavior and integration of lateralized telencephalic input. The evidence for clear interaction in our experimental paradigm suggests that telencephalic vocal control also uses a similar mechanism. Furthermore, species differences in the response of the respiratory system to stimulation show parallels to differences in the respiratory patterns of song, suggesting that the interactive production of respiratory rhythms is manifested in species-specific specialization of the involved circuitry. © 2012 the American Physiological Society.

De La Llave E.,University of Buenos Aires | Molinero V.,University of Utah | Scherlis D.A.,University of Buenos Aires
Journal of Chemical Physics | Year: 2010

Molecular dynamics simulations of water in cylindrical hydrophilic pores with diameters of 1.5 and 3 nm were performed to explore the phase behavior and the nucleation dynamics of the confined fluid as a function of the percentage of volume filled f. The interactions of water with the pore wall were considered to be identical to the interactions between water molecules. At low water contents, all the water is adsorbed to the surface of the pore. A second phase consisting of a liquid plug appears at the onset filling for capillary condensation, fonset =27% and 34% for the narrow and wide pores, respectively. In agreement with experimental results for silica pores, the liquid phase appears close to the equilibrium filling feq in the 1.5 nm pore and under conditions of strong surface supersaturations for the 3 nm pore. After condensation, two phases, a liquid plug and a surface-adsorbed phase, coexist in equilibrium. Under conditions of phase coexistence, the water surface density Tcoex was found to be independent of the water content and the diameter of the pore. The value of Tcoex found in the simulations (∼3 nm-2) is in good agreement with experimental results for silica pores, suggesting that the interactions of water with silica and with itself are comparable. The surface-adsorbed phase at coexistence is a sparse monolayer with a structure dominated by small water clusters. We characterize the density and structure of the liquid and surface phases, the nucleation mechanism of the water plug, and the effect of surface hydrophilicity on the two-phase equilibrium and hysteresis. The results are discussed in light of experiments and previous simulations. © 2010 American Institute of Physics.

Moore E.B.,University of Utah | De La Llave E.,University of Buenos Aires | Welke K.,University of Utah | Scherlis D.A.,University of Buenos Aires | Molinero V.,University of Utah
Physical Chemistry Chemical Physics | Year: 2010

The nucleation, growth, structure and melting of ice in 3 nm diameter hydrophilic nanopores are studied through molecular dynamics simulations with the mW water model. The melting temperature of water in the pore was Tporem = 223 K, 51 K lower than the melting point of bulk water in the model and in excellent agreement with experimental determinations for 3 nm silica pores. Liquid and ice coexist in equilibrium at the melting point and down to temperatures as low as 180 K. Liquid water is located at the interface of the pore wall, increasing from one monolayer at the freezing temperature, Tporef = 195 K, to two monolayers a few degrees below Tporem. Crystallization of ice in the pore occurs through homogeneous nucleation. At the freezing temperature, the critical nucleus contains ∼75 to 100 molecules, with a radius of gyration similar to the radius of the pore. The critical nuclei contain features of both cubic and hexagonal ice, although stacking of hexagonal and cubic layers is not defined until the nuclei reach ∼150 molecules. The structure of the confined ice is rich in stacking faults, in agreement with the interpretation of X-ray and neutron diffraction experiments. Though the presence of cubic layers is twice as prevalent as hexagonal ones, the crystals should not be considered defective Ic as sequences with more than three adjacent cubic (or hexagonal) layers are extremely rare in the confined ice. © 2010 the Owner Societies.

Dorso C.O.,University of Buenos Aires | Gimenez Molinelli P.A.,University of Buenos Aires | Lopez J.A.,University of Texas at El Paso
Physical Review C - Nuclear Physics | Year: 2012

Neutron star crusts are studied using a classical molecular dynamics model developed for heavy-ion reactions. After the model is shown to produce a plethora of the so-called pasta shapes, a series of techniques borrowed from nuclear physics, condensed matter physics, and topology is used to craft a method that can be used to characterize the shape of the pasta structures in an unequivocal way. © 2012 American Physical Society.

Bono A.,Instituto Nacional de Tecnologia Agropecuaria | Alvarez R.,University of Buenos Aires
Archives of Agronomy and Soil Science | Year: 2013

Use of the nitrogen balance sheet method as a fertilization strategy in the semi-arid Pampas of Argentina is restricted because of a lack of available information regarding nitrogen mineralization in its coarse soils. Our objective was to determine nitrogen mineralization during corn (Zea mays L.) and following wheat (Triticum aestivum L.) growing cycles under contrasting tillage systems in a representative soil of the region. Mineralized nitrogen from decomposing residues was estimated using the litter bag method and mineralization from soil organic matter using a mass balance approach. Soil water content was higher under no-till during the corn growing season and no differences were detected for wheat during this period. Soil temperature was practically not affected by tillage system. Biomass and nitrogen absorption were higher under no-till than under disk till in corn (p ≤ 0.05), as were nitrogen mineralization from residues and organic matter (p ≤ 0.05). In wheat, no differences in biomass, nitrogen absorption and mineralization were detected between treatments. Mineralization during crop growing cycles accounted for 44.8-67.5% of the absorbed nitrogen. Differences in nitrogen mineralization between tillage systems resulted from the greater water availability under no-till than under disk till during the summer. © 2013 Copyright Taylor and Francis Group, LLC.

Dorso C.A.,University of Buenos Aires | Molinelli P.A.G.,University of Buenos Aires | Lopez J.A.,University of Texas at El Paso
Journal of Physics G: Nuclear and Particle Physics | Year: 2011

Experiments with rare isotopes are shedding light on the role isospin plays in the equation of state (EoS) of nuclear matter, and isoscaling - a straightforward comparison of reactions with different isospin - could deliver valuable information about it. In this work, we test this assertion pragmatically by comparing molecular dynamics simulations of isoscaling reactions using different EoS and looking for changes in the isoscaling parameters; to explore the possibility of isoscaling carrying information from the hot-and-dense stage of the reaction, we perform our study in confined and expanding systems. Our results indicate that indeed isoscaling can help us learn about the nuclear EoS, but only in some ranges of excitation energies. © 2011 IOP Publishing Ltd.

Pedetta A.,University of Buenos Aires | Parkinson J.S.,University of Utah | Studdert C.A.,University of Buenos Aires
Molecular Microbiology | Year: 2014

Chemical signals sensed on the periplasmic side of bacterial cells by transmembrane chemoreceptors are transmitted to the flagellar motors via the histidine kinase CheA, which controls the phosphorylation level of the effector protein CheY. Chemoreceptor arrays comprise remarkably stable supramolecular structures in which thousands of chemoreceptors are networked through interactions between their cytoplasmic tips, CheA, and the small coupling protein CheW. To explore the conformational changes that occur within this protein assembly during signalling, we used in vivo cross-linking methods to detect close interactions between the coupling protein CheW and the serine receptor Tsr in intact Escherichia coli cells. We identified two signal-sensitive contacts between CheW and the cytoplasmic tip of Tsr. Our results suggest that ligand binding triggers changes in the receptor that alter its signalling contacts with CheW (and/or CheA). © 2014 John Wiley & Sons Ltd.

Macias D.,Instituto Nacional de Tecnologia Agropecuaria | Mazia N.,University of Buenos Aires | Jacobo E.,University of Buenos Aires
Basic and Applied Ecology | Year: 2014

Woody encroachment in savannas is a worldwide concern, and there is growing consensus that anthropogenic activities play a central role in changing tree - grass interactions. We evaluated the influence of livestock grazing and neighborhood interactions on seedling emergence and survival of the native tree Acacia caven in wet savannas of northeastern Argentina. We hypothesized that grazing and grass competition act as biotic barriers limiting tree recruitment, but the relative magnitude of such barriers differs according to grass patch type. In two consecutive years (cohort 1 and 2) we sowed seeds and transplanted seedlings of Acacia in two grass patch types (prostrate/palatable and tussock/unpalatable grasses) in both, grazed and ungrazed plots. Each grass patch type was further manipulated to create three levels of grass competition (unclipped control, above-ground biomass removal and total biomass removal).Cattle grazing diminished seedling emergence of both cohorts and seedling survival of cohort 1. The effect of grass competition changed according to grass patch type. Prostrate grass cover enhanced emergence but lowered early survival, while tussock grass cover and also its total biomass removal facilitated early survival. During the second year, a severe drought drastically reduced Acacia recruitment, and it was strong enough to eliminate any grazing effects although the effect of grass competition on seedling establishment remained significant.Our results suggest that grazing and grass competition additively diminished the risk of woody establishment in this wet savanna. However, the stocking rate should be carefully balanced, thus contributing to the maintenance of a competitive grass cover to limit tree recruitment. © 2014 Gesellschaft für Ökologie.