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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.

Giarratano E.,CONICET | Gil M.N.,CONICET | Malanga G.,University of Buenos Aires
Ecotoxicology and Environmental Safety | Year: 2014

In this study, we assessed in gills of native ribbed mussels Aulacomya atra atra from three sites within Nuevo Gulf (Northern Patagonia) several biomarkers such as reactive oxygen species (ROS), lipid radicals (LR), malondialdehyde (MDA), superoxide dismutase (SOD), catalase (CAT), glutathione S-transferase (GST) and metallothionein (MT). Furthermore, concentrations of main trace metals (Fe, Al, Zn, Cu, Cd and Pb) were quantified in mussel tissue. Results showed significant induction of SOD, GST, MT and MDA, as well as, higher concentration of Fe, Al and Cd in winter than in summer. The high MDA content measured in mussels from Folías Wreck seemed to be caused by the very high levels of Fe that would come from the corrosion of the vessel. Mussels from the control site Punta Cuevas presented the lowest levels of Cd and the highest of Al in winter. Despite positive correlations were found between Al and GST and MT, no spatial differentiation was detected in those biomarkers. On the other hand, MT was only related to Al been most likely influenced by environmental variables than by the trace metals. It has to be highlighted that the relationship detected among water temperature, nutrients and antioxidant responses in gills is probably related to the fact that this tissue is in direct contact with water and it is sensitive to its fluctuations. Taking into account that mussel gill is a tissue actively proliferating and the first target of contaminants present in water, so that changes in its antioxidant system can provide an earlier warning signal than in other tissues. © 2014 Elsevier Inc.

Stern D.L.,Howard Hughes Medical Institute | Franke N.,University of Buenos Aires
Philosophical Transactions of the Royal Society B: Biological Sciences | Year: 2013

In this paper, we provide a historical account of the contribution of a single line of research to our current understanding of the structure of cis-regulatory regions and the genetic basis for morphological evolution. We revisit the experiments that shed light on the evolution of larval cuticular patterns within the genus Drosophila and the evolution and structure of the shavenbaby gene. We describe the experiments that led to the discovery that multiple genetic changes in the cis-regulatory region of shavenbaby caused the loss of dorsal cuticular hairs (quaternary trichomes) in first instar larvae of Drosophila sechellia. We also discuss the experiments that showed that the convergent loss of quaternary trichomes in D. sechellia and Drosophila ezoana was generated by parallel genetic changes in orthologous enhancers of shavenbaby. We discuss the observation that multiple shavenbaby enhancers drive overlapping patterns of expression in the embryo and that these apparently redundant enhancers ensure robust shavenbaby expression and trichome morphogenesis under stressful conditions. All together, these data, collected over 13 years, provide a fundamental case study in the fields of gene regulation and morphological evolution, and highlight the importance of prolonged, detailed studies of single genes.

Roussos A.,University of Buenos Aires
Psychotherapy | Year: 2013

The articles included in this special section are based on the works presented in a panel named Clients Talking About Therapy, which took place during the 43rd International Annual Meeting of the Society for Psychotherapy Research in Virginia Beach. One of the main issues at the time of the panel was the difficulty in reaching an agreement about what change represents in psychotherapy research. In this introduction I very briefly present some of the debates that are currently going on about change and the role of qualitative research in that debate. The articles included are qualitative investigations that study the value of clients' perspectives from different vantage points. The authors used in-depth interviews, which allow interviewees to communicate whatever they think, enabling the emergence of new perspectives. I look forward to the application of the information obtained among these studies, in the development of applied clinical knowledge. ©2013 American Psychological Association. ©2013 American Psychological Association.

This article is focused on the characteristics and aims of the Chemistry of Natural Products analyzing the required knowledge from other fields to carry out research. Through a brief historical development, it can be observed that it is related with various branches of Chemistry, including Organic Chemistry, Biological Chemistry and Bioanalytical Chemistry as well as Clinical Biochemistry, among others. Prospects in this field are provided, showing trends in research and in the international chemical industry. A multidisciplinary approach is evident in the research projects shown herein.

Gonzalez R.M.,CONICET | Iusem N.D.,CONICET | Iusem N.D.,University of Buenos Aires
Planta | Year: 2014

Investigating how plants cope with different abiotic stresses—mainly drought and extreme temperatures—is pivotal for both understanding the underlying signaling pathways and improving genetically engineered crops. Plant cells are known to react defensively to mild and severe dehydration by initiating several signal transduction pathways that result in the accumulation of different proteins, sugar molecules and lipophilic anti-oxidants. Among the proteins that build up under these adverse conditions are members of the ancestral ASR (ABA-stress-ripening) family, which is conserved in the plant kingdom but lacks orthologs in Arabidopsis. This review provides a comprehensive summary of the state of the art regarding ASRs, going back to the original description and cloning of the tomato ASR cDNA. That seminal discovery sparked worldwide interest amongst research groups spanning multiple fields: biochemistry, cell biology, evolution, physiology and epigenetics. As these proteins function as both chaperones and transcription factors; this review also covers the progress made on relevant molecular features that account for these dual roles—including the recent identification of their target genes—which may inspire future basic research. In addition, we address reports of drought-tolerant ASR-transgenic plants of different species, highlighting the influential work of authors taking more biotechnological approaches. © 2014, Springer-Verlag Berlin Heidelberg.

Schaff J.-F.,University of Nice Sophia Antipolis | Capuzzi P.,University of Buenos Aires | Labeyrie G.,University of Nice Sophia Antipolis | Vignolo P.,University of Nice Sophia Antipolis
New Journal of Physics | Year: 2011

We study experimentally and theoretically the controlled transfer f harmonically trapped ultracold gases between different quantum states. n particular, we experimentally demonstrate a fast decompression anddisplacement of both a non-interacting gas and an interacting Bose-Einstein ondensate, which are initially at equilibrium. The decompression parameters re engineered such that the final state is identical to that obtained after a erfectly adiabatic transformation despite the fact that the fast decompression is erformed in the strongly non-adiabatic regime. During the transfer the atomic ample goes through strongly out-of-equilibrium states, while the external onfinement is modified until the system reaches the desired stationary state. The cheme is theoretically based on the invariants of motion and scaling equation echniques and can be generalized to decompression trajectories including an rbitrary deformation of the trap. It is also directly applicable to arbitrary initial on-equilibrium states. © IOP Publishing Ltd and Deutsche Physikalische Gesellschaft.

Valentinuzzi M.E.,University of Buenos Aires
IEEE pulse | Year: 2012

On the basis of the strict exclusion of the vis vitalis, the demand was raised by Carl Ludwig, Helmholtz, Du Bois-Reymond, and Brucke for a physiology which was causal-analytical and physically and chemically experimental. If, out of these four investigators, we pick Ludwig as the actual founder of modern physiology, the grounds for this must be justified specifically. That modern physiology is not to be contemplated without the works of the three great students of Johannes Muller is explicitly emphasized. However, Carl Ludwig occupies a special position for physiology.

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.

Albores P.,Johannes Gutenberg University Mainz | Albores P.,University of Buenos Aires | Rentschler E.,Johannes Gutenberg University Mainz
Dalton Transactions | Year: 2010

We are reporting the first supramolecular dimeric units of basic carboxylates. The neutral [FeIII 2MIIO] motif for different 3d M metals is covalently bound through 2,2′-bipyrimidine. We have structurally characterized the hexanuclear clusters and the related trinuclear building blocks. Their magnetic properties have been fully analyzed and DFT calculations have been performed as a supplementary tool. All results evidence a weak antiferromagnetic interaction through the bpym bridge between isolated spin ground states (in some examples) arising from intra-Fe 2MO core exchange couplings. © The Royal Society of Chemistry 2010.

Nabity P.D.,Urbana University | Zavala J.A.,University of Buenos Aires | Delucia E.H.,Urbana University
Journal of Experimental Botany | Year: 2013

Herbivory initiates a shift in plant metabolism from growth to defence that may reduce fitness in the absence of further herbivory. However, the defence-induced changes in carbon assimilation that precede this reallocation in resources remain largely undetermined. This study characterized the response of photosynthesis to herbivore induction of jasmonic acid (JA)-related defences in Nicotiana attenuata to increase understanding of these mechanisms. It was hypothesized that JA-induced defences would immediately reduce the component processes of photosynthesis upon attack and was predicted that wild-type plants would suffer greater reductions in photosynthesis than plants lacking JA-induced defences. Gas exchange, chlorophyll fluorescence, and thermal spatial patterns were measured together with the production of defence-related metabolites after attack and through recovery. Herbivore damage immediately reduced electron transport and gas exchange in wild-type plants, and gas exchange remained suppressed for several days after attack. The sustained reductions in gas exchange occurred concurrently with increased defence metabolites in wild-type plants, whereas plants lacking JA-induced defences suffered minimal suppression in photosynthesis and no increase in defence metabolite production. This suppression in photosynthesis occurred only after sustained defence signalling and defence chemical mobilization, whereas a short bout of feeding damage only transiently altered components of photosynthesis. It was identified that lipoxygenase signalling interacted with photosynthetic electron transport and that the resulting JA-related metabolites reduced photosynthesis. These data represent a metabolic cost to mounting a chemical defence against herbivory and link defence-signalling networks to the differential effects of herbivory on photosynthesis in remaining leaf tissues in a time-dependent manner. © 2012 © 2012 The Authors.

Paruelo J.M.,University of Buenos Aires | Paruelo J.M.,CONICET
Forest Policy and Economics | Year: 2012

The expansion of industrial tree plantations in South America is a case of land transformation that has already generated conflicts at the local, national and international levels. In a recent article, Vihervaara et al. (2012) present a controversial analysis, mainly for the potential use of some of their results; they suggest that the general attitude among the local people toward an increment in tree plantations and toward the forest industry is positive. In this article I discuss the results and conclusions of the Vihervaara et al. article, particularly those related to the definition of the ecosystem services concept, the definition of stakeholders and the approaches to deriving their perception, and the available evidence on the impacts of grassland afforestation in Uruguay. © 2012 Elsevier B.V.

Busi R.,University of Western Australia | Vila-Aiub M.M.,University of Western Australia | Vila-Aiub M.M.,University of Buenos Aires | Powles S.B.,University of Western Australia
Heredity | Year: 2011

The dynamics of herbicide resistance evolution in plants are influenced by many factors, especially the biochemical and genetic basis of resistance. Herbicide resistance can be endowed by enhanced rates of herbicide metabolism because of the activity of cytochrome P450 enzymes, although in weedy plants the genetic control of cytochrome P450-endowed herbicide resistance is poorly understood. In this study we have examined the genetic control of P450 metabolism-based herbicide resistance in a well-characterized Lolium rigidum biotype. The phenotypic resistance segregation in herbicide resistant and susceptible parents, F1, F2 and backcross (BC) families was analyzed as plant survival following treatment with the chemically unrelated herbicides diclofop-methyl or chlorsulfuron. Dominance and nuclear gene inheritance was observed in F1 families when treated at the recommended field doses of both herbicides. The segregation values of P450 herbicide resistance phenotypic traits observed in F2 and BC families was consistent with resistance endowed by two additive genes in most cases. In obligate out-crossing species such as L. rigidum, herbicide selection can easily result in accumulation of resistance genes within individuals. © 2011 Macmillan Publishers Limited All rights reserved 0018-067X/11.

Palacios-Jaraquemada J.M.,Center for Medical Education and Clinical Research | Palacios-Jaraquemada J.M.,University of Buenos Aires
Acta Obstetricia et Gynecologica Scandinavica | Year: 2011

Objective. To analyze the efficacy of surgical techniques to stop excessive obstetric bleeding. Design. Retrospective follow up. Setting. Center for Medical Education and Clinical Research and a total of twelve hospitals in Buenos Aires. Population. Five hundred and thirty-nine consecutive patients were included: 361 had placenta accreta-percreta, 114 uterine atony, 19 cervical scar pregnancy, 21 placenta previa and 24 uterine-cervical-vaginal tears. Three hundred and forty-seven women had surgery, of whom 192 were emergencies. Methods. The surgical techniques included selective arterial ligation and compression procedures. The effectiveness of the techniques was assessed by cessation of bleeding according to source. Follow up included hysteroscopy of 100 patients and magnetic resonance imaging of 341 patients. Main outcome measures. Strong association between topographical uterine irrigation areas and surgical hemostatic technique was established. Results. Hemorrhage stopped following arterial ligation or compression sutures in 499 women, but hysterectomy was needed in 40. In cervical, lower segment and upper vaginal bleeding, Cho's compression sutures proved to be an efficient and simple procedure. Most surgical hemostatic failures that led to hysterectomy occurred in women with severe hemodynamic deterioration and coagulopathy. Two women died due to multiorgan failure. After surgery, 116 successful pregnancies were reported. Conclusions. Bilateral occlusions of the uterine artery or its branches were useful procedures to stop upper uterine bleeding. Square sutures were a simple and effective procedure to control lower genital tract bleeding. © 2011 The Authors Acta Obstetricia et Gynecologica Scandinavica© 2011 Nordic Federation of Societies of Obstetrics and Gynecology.

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.

Zavala J.A.,University of Buenos Aires | Nabity P.D.,Urbana University | DeLucia E.H.,Urbana University
Annual Review of Entomology | Year: 2013

By changing the chemical composition of foliage, the increase in atmospheric CO2 is fundamentally altering insect herbivory. The responses of folivorous insects to these changes is, however, highly variable. In this review we highlight emerging mechanisms by which increasing CO 2 alters the defense chemistry and signaling of plants. The response of allelochemicals affecting insect performance varies under elevated CO 2, and results suggest this is driven by changes in plant hormones. Increasing CO2 presses the production of jasmonates and ethylene and increases the production of salicylic acid, and these differential responses of plant hormones affect specific secondary chemical pathways. In addition to changes in secondary chemistry, elevated CO2 decreases rates of water loss from leaves, increases temperature and feeding rates, and alters nutritional content. New insights into the mechanistic responses of secondary chemistry to elevated CO2 increase our ability to predict the ecological and evolutionary responses of plants attacked by insects. © 2013 by Annual Reviews. All rights reserved.

Torre M.S.,University of Buenos Aires | Gavrielides A.,Air Force Research Lab | Masoller C.,Polytechnic University of Catalonia
Optics Express | Year: 2011

We study the dynamics of two vertical-cavity surface-emitting lasers (VCSELs) mutually coupled such that the natural lasing polarization of each laser is rotated by 90 degrees and then is injected into the other laser. Simulations based on the spin-flip model show transient square-wave polarization switchings before a stationary state is reached. The influence of various model parameters on the duration of the stochastic transient time and on the lasers' dynamics in the stationary state is investigated. © 2011 Optical Society of America.

Sanchez G.A.,University of Buenos Aires
Acta odontológica latinoamericana : AOL | Year: 2010

Myotoxic effects of local anesthetics on skeletal musclefibers involve the inhibition ofsarcoplasmic reticulum Ca2+ -dependent ATPase activity and Ca2 transport. Lidocaine is a local anesthetic frequently used to relieve the symptoms of trigeminal neuralgia. The aim of this work was to test the inhibitory and/or stimulatory effect of lidocaine on sarcoplasmic reticulum Ca2+ -dependent ATPase isolated from rabbit temporalis muscle. Ca2+ -dependent ATPase activity was determined by a colorimetric method Calcium-binding to the Ca dependent ATPase, Ca2+ transport, and phosphorylation of the enzyme by ATP were determined with radioisotopic techniques. Lidocaine inhibited the Ca2+ -dependent ATPase activity in a concentration-dependent manner. The preincubation of the sarcoplasmic reticulum membranes with lidocaine enhanced the Ca2+ dependent ATPase activity in the absence of calcium ionophore. Lidocaine also inhibited both Ca2+ uptake and enzyme phosphorylation by ATP but had no effect on Ca2+ -binding to the enzyme. We conclude that the effect of lidocaine on the sarcoplasmic reticulum Ca2+ -dependent ATPase from temporalis muscle is due to the drug's direct interaction with the enzyme and the increased permeability of the sarcoplasmic reticulum membrane to Ca.

Lechner B.E.,University of Buenos Aires | Alberto E.,CONICET
Revista Iberoamericana de Micologia | Year: 2011

Background: The species of genus Pleurotus are worldwide cultivated. Aims: To evaluate growth, yield production and morphological variations of fruiting bodies obtained from the cultivation of fourteen naturally occurring Pleurotus strains isolated from Argentina. Methods: The strains growth was tested at different temperatures on Nobles' medium. Substrates assayed were: supplemented Salix sawdust, supplemented and non supplemented wheat straw. The species studied were Pleurotus albidus, Pleurotus cystidiosus, Pleurotus djamor, Pleurotus ostreatus and Pleurotus pulmonarius. Results: The maximum rate growth was reached by strains of P. pulmonarius, P. albidus, and P. ostreatus. No relationship was found when optimal mycelium growth, incubation time and yields were compared. The highest yield was obtained with P. albidus on wheat straw (biological efficiency 171.3%) which overcame in 82% the yield obtained for the commercial strain in the same substrate. When morphological variations were analyzed for each species, significant differences were found among strains. It was also possible to find a naturally occurring strain of P. ostreatus with better biological efficiency than the commercial strain assayed. Conclusions: We propose the study of naturally occurring strains as a useful practice to improve yields of species of Pleurotus. Due to the high biological efficiency obtained we propose P. albidus as a new species for commercial production. © 2011 Revista Iberoamericana de Micología.

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.

Zunino L.,CONICET | Rosso O.A.,Federal University of Minas Gerais | Rosso O.A.,University of Buenos Aires | Soriano M.C.,University of the Balearic Islands
IEEE Journal on Selected Topics in Quantum Electronics | Year: 2011

The time evolution of the output of a semiconductor laser subject to delayed optical feedback can exhibit high-dimensional chaotic fluctuations. In this contribution, our aim is to quantify the degree of unpredictability of this hyperchaotic time evolution. To that end, we estimate permutation entropy, a novel information-theory-derived quantifier particularly robust in a noisy environment. The permutation entropy is defined as a functional of a symbolic probability distribution, evaluated using the Bandt-Pompe recipe to assign a probability distribution function to the time series generated by the chaotic system. This measure quantifies the diversity of orderings present in the associated time series. In order to evaluate the performance of this novel quantifier, we compare with the results obtained by using a more standard chaos quantifier, namely the Kolmogorov-Sinai entropy. Here, we present numerical results showing that the permutation entropy, evaluated at specific time-scales involved in the chaotic regime of the semiconductor laser subject to optical feedback, give valuable information about the degree of unpredictability of the chaotic laser dynamics. The influence of additive observational noise on the proposed tool is also investigated. © 2011 IEEE.

Carrica M.C.,CONICET | Fernandez I.,CONICET | Marti M.A.,University of Buenos Aires | Paris G.,CONICET | Goldbaum F.A.,CONICET
Molecular Microbiology | Year: 2012

Brucella spp. are facultative intracellular bacteria pathogenic for many mammalian species including humans, causing a disease called brucellosis. Learning how Brucella adapts to its intracellular niche is crucial for understanding its pathogenesis mechanism, allowing for the development of new and more effective vaccines and treatments against brucellosis. Brucella pathogenesis resides mostly in its ability to adapt to the harsh environmental conditions encountered during host infection such as the oxygen depletion. The mechanism by which Brucella senses the oxygen tension and triggers its environmental adaptation is unknown. In this work we show that the Brucella abortus NtrY/NtrX two-component system is involved in oxygen sensing through a haem group contained in a Per-ARNT-SIM (PAS) domain of the NtrY histidine kinase. The NtrY haem iron can be reduced to the ferrous form and is rapidly oxidized to the ferric form in presence of oxygen. Importantly, we show that the oxidation state of the haem iron modulates the autokinase activity, being the anoxygenic reduced ferrous form the signalling state of NtrY. Also, we show that ntrY gene expression increases under low oxygen tension and that NtrY transfers its signal to its cognate response regulator NtrX, regulating in this way the expression of nitrogen respiration enzymes. Based on these findings, we postulate that NtrY acts as a redox sensor in Brucella spp. © 2012 Blackwell Publishing Ltd.

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.

Thijssen V.L.,VU University Amsterdam | Rabinovich G.A.,CONICET | Rabinovich G.A.,University of Buenos Aires | Griffioen A.W.,VU University Amsterdam
Cytokine and Growth Factor Reviews | Year: 2013

Galectins are a family of carbohydrate binding proteins with a broad range of cytokine and growth factor-like functions in multiple steps of cancer progression. They contribute to tumor cell transformation, promote tumor angiogenesis, hamper the anti-tumor immune response, and facilitate tumor metastasis. Consequently, galectins are considered as multifunctional targets for cancer therapy. Interestingly, many of the functions related to tumor progression can be linked to galectins expressed by endothelial cells in the tumor vascular bed. Since the tumor vasculature is an easily accessible target for cancer therapy, understanding how galectins in the tumor endothelium influence cancer progression is important for the translational development of galectin-targeting therapies. © 2013 Elsevier Ltd.

Jorge F.,University of Buenos Aires
Physiological Reviews | Year: 2010

The mechanism of epithelial fluid transport remains unsolved, which is partly due to inherent experimental difficulties. However, a preparation with which our laboratory works, the corneal endothelium, is a simple leaky secretory epithelium in which we have made some experimental and theoretical headway. As we have reported, transendothelial fluid movements can be generated by electrical currents as long as there is tight junction integrity. The direction of the fluid movement can be reversed by current reversal or by changing junctional electrical charges by polylysine. Residual endothelial fluid transport persists even when no anions (hence no salt) are being transported by the tissue and is only eliminated when all local recirculating electrical currents are. Aquaporin (AQP) 1 is the only AQP present in these cells, and its deletion in AQP1 null mice significantly affects cell osmotic permeability (by ∼40%) but fluid transport much less (∼20%), which militates against the presence of sizable water movements across the cell. In contrast, AQP1 null mice cells have reduced regulatory volume decrease (only 60% of control), which suggests a possible involvement of AQP1 in either the function or the expression of volume-sensitive membrane channels/transporters. A mathematical model of corneal endothelium we have developed correctly predicts experimental results only when paracellular electro-osmosis is assumed rather than transcellular local osmosis. Our evidence therefore suggests that the fluid is transported across this layer via the paracellular route by a mechanism that we attribute to electro-osmotic coupling at the junctions. From our findings we have developed a novel paradigm for this preparation that includes 1) paracellular fluid flow; 2) a crucial role for the junctions; 3) hypotonicity of the primary secretion; and 4) an AQP role in regulation rather than as a significant water pathway. These elements are remarkably similar to those proposed by the laboratory of Adrian Hill for fluid transport across other leaky epithelia. Copyright © 2010 the American Physiological Society.

Feldstein C.A.,University of Buenos Aires
Clinical and Experimental Hypertension | Year: 2016

ABSTRACT: Obstructive sleep apnea (OSA) is a rather common chronic disorder, associated with increased prevalence of hypertension. The pathophysiological mechanisms for hypertension in OSA are at least in part linked to intermittent hypoxia developed during nightly hypopneas and apneas. Hypoxemia stimulates sympathetic overactivity, systemic inflammation, oxidative stress, and endothelial dysfunction. However, it appears that intermittent hypoxemia is not the only factor in the development of hypertension in OSA. Supplemental oxygen therapy that improved oxyhemoglobin saturation to similar levels to those achieved with CPAP treatment did not reduce BP. In this scenario, it could be proposed that hypoxemia acts as a trigger of sympathetic overdrive, which when set is the main factor in the development of hypertension in OSA. This review appraises evidence provided by randomized controlled trials on the BP-lowering effectiveness of continuous positive airway pressure (CPAP) treatment of OSA patients with nonresistant and resistant hypertension. It suggests that CPAP treatment is more effective in treating resistant hypertension than nonresistant hypertension. A possible explanation is that sympathetic overactivity and altered vascular reactivity in OSA could be more severe in resistant hypertension than in nonresistant hypertension. An intricate interaction among compliance, adherence, and their interaction with demographic characteristics, genetic factors, and comorbidities of the population included might explain the differences found between trials on their influence over the antihypertensive effectiveness of CPAP. Further long-term trials are needed in hypertensive OSA patients to assess whether CPAP treatment in OSA patients consistently restores physiological nocturnal BP fall and adjusts resting and circadian heart rate. © 2016 Taylor & Francis.

Gomez R.O.,University of Buenos Aires
Cretaceous Research | Year: 2016

Pipid frogs are fully aquatic frogs that today inhabit freshwater environments of southern continents on both sides of the Atlantic Ocean, with a fairly good fossil record dating back to the Cretaceous. Here I report on fossils from the Allen Formation (upper Campanian-lower Maastrichtian), Río Negro Province, Argentina, that are ascribed to a new genus and species of pipid. In order to assess the evolutionary relationships of the new taxon, which is represented by sphenethmoids, otic capsules, ilia, humeri, and vertebrae, cladistic analyses of a data matrix of 165 osteological characters scored for 36 taxa were performed. The results are congruent with previous hypotheses of pipoid interrelationships and consistently place the new taxon as part of the lineage today represented by the African xenopodines. Temporal calibration of the phylogenetic tree based on the fossil record imply that the origin and early diversification of crown-group Pipidae might have occurred during the Early Cretaceous, prior to the final breakup of western Gondwana. This study highlights the importance of including fossils, even fragmentary ones, directly in phylogenetic analyses in order to disentangling how, when, and where pipid frogs diversified. © 2016 Elsevier Ltd.

Blanco Crivelli X.,University of Buenos Aires
Frontiers in cellular and infection microbiology | Year: 2012

Shigatoxigenic Escherichia coli (STEC) strains are worldwide zoonotic pathogen responsible for different cases of human disease including hemolytic uremic syndrome (HUS). Transmission of STEC to humans occurs through the consumption of food and water contaminated by faeces of carriers and by person-to-person contact. The objective of this study was two-fold: (1) to investigate whether synanthropic rodents are possible reservoirs of STEC in the urban area and (2) whether a particular genus out of synanthropic rodent is the principal carrier of STEC. One hundred and forty-five rodents were captured in Buenos Aires City. Screening for stx1/stx2 and rfbO157 was done by PCR from the confluence zone. STEC isolates were further characterized with biochemical tests by standard methods. Additional virulence factors (eae, ehxA, and saa) were also determined by PCR. Forty-one of the rodents were necropsied and sample of kidney and small and large intestine were taken for histopathological diagnosis. The samples sections were stained with hematoxylin-eosin, and observed by light microscopy to evaluate the systemic involvement of these species in natural infections. STEC was isolated from seven out of 27 suspect animals at screening. The following genotypes were found in the STEC strains: stx1/stx2/ehxA (1), stx2 (4), stx2/ehxA (1), stx2/ehxA/eae (1). Neither gross nor microscopic lesions compatible with those produced by Shiga toxin were observed in the studied organs of necropsied rodents. The bivariate analysis including the 145 rodent's data showed that the isolation of STEC is associated positively to Rattus genus. This synanthropic species may play a role in the transmissibility of the agent thus being a risk to the susceptible population. Their control should be included specifically in actions to dismiss the contamination of food and water by STEC in the urban area, as additional strategies for epidemiological control.

Eggeling C.,Max Planck Institute for Biophysical Chemistry | Eggeling C.,Weatherall Institute of Molecular Medicine | Willig K.I.,Max Planck Institute for Biophysical Chemistry | Barrantes F.J.,University of Buenos Aires
Journal of Neurochemistry | Year: 2013

Recent developments in fluorescence far-field microscopy such as STED microscopy have accomplished observation of the living cell with a spatial resolution far below the diffraction limit. Here, we briefly review the current approaches to super-resolution optical microscopy and present the implementation of STED microscopy for novel insights into live cell mechanisms, with a focus on neurobiology and plasma membrane dynamics. © 2013 International Society for Neurochemistry.

Aedeagal morphology of two sibling cactophilic species, Drosophila buzzatii Patterson & Wheeler and Drosophila koepferae Fontdevila & Wasserman, was analyzed in nine allopatric and three sympatric locations throughout South America. Morphological differences were detected for both aedeagus size and shape between sympatric and allopatric populations of D. buzzatii, despite the significant variability within both groups. Populations of D. buzzatii sympatric with D. koepferae displayed smaller aedeagus than the allopatric ones as well as more differentiated aedeagus shape. The shape differences were non-allometric and mainly consisted in a change of curvature of the dorsal margin of the aedeagus being more pronounced in males from populations sympatric with D. koepferae. It is concluded that aedeagal morphology presented some degree of character displacement in both size and shape in populations of D. buzzatii in sympatry with D. koepferae. These results might suggest the existence of mechanisms of interspecific recognition and hybridization prevention between these species that include the morphology of the male genitalia. © 2012 Sociedade Entomológica do Brasil.

Czornyj L.,Servicio de Neurologia | Lazarowski A.,University of Buenos Aires
Frontiers in Bioscience - Landmark | Year: 2014

ABC-transporters prevent the access of antiepileptic drugs into brain parenchyma, which partly explains why seizures are frequently refractory to AEDs treatment. Overexpression of aABC-transporters and stemcell markers including CD34, have been detected in malformations of cortical development (MCD) and brain tumors. ABC-transporters are constitutively expressed during maturation of normal progenitor stem-cells and cancer stem-cells. These abnormal/immature cells of MCD or brain tumors play an active role in the epileptogenesis but the precise nature of this phenomenon is unclear. Irrespective of their property in the pharmacoresistance, ABCB1-transporter P-glycoprotein also play a role in the membrane depolarization, suggesting that constitutive P-glycprotein overexpression in MCD and brain tumors could explain their epileptogeneic properties. MCD as wells as brain tumors arise from abnormal progenitor cells, where ABC-t together with others stem cell markers, could help to better identification of these abnormal progenitor cells and serve as biomarker of risk for seizure relapse after epilepsy surgery.

Tell G.,University of Buenos Aires
Advances in Limnology | Year: 2014

Argentina is located in the southern part of South America, with climates ranging from warm, temperate to cold, and encompassing several wetlands and a variety of freshwater bodies such as lakes, reservoirs, ponds, rivers and shallow lakes, where phytoplankton may develop. A remarkably large number of taxa have been reported in taxonomic monographs, inventories of regional floras, and floristic lists in ecological papers. Several planktonic algae have a wide geographical distribution and can be found in other parts of the world with similar environmental conditions. Other habitats, particularly those in warm and circumpolar regions, harbour species and infraspecific entities with a limited geographical distribution. On the other hand, some taxa have been recorded only in this country and are thus considered endemic. Taxonomic studies of different groups, mainly Chlorococcales, Desmidiaceae, Euglenophyceae and Diatomophyceae, have revealed several species and infraspecific taxa new to science. The present article provides an overall picture of phytoplankton diversity in the different regions of Argentina. © 2014 E. Schweizerbart'sche Verlagsbuchhandlung, 70176 Stuttgart, Germany.

Vaccaro M.I.,University of Buenos Aires
International Journal of Cell Biology | Year: 2012

Timing is everything. That's especially true when it comes to the activation of enzymes created by the pancreas to break down food. Pancreatic enzymes are packed in secretory granules as precursor molecules called zymogens. In physiological conditions, those zymogens are activated only when they reach the gut, where they get to work releasing and distributing nutrients that we need to survive. If this process fails and the enzymes are prematurely activated within the pancreatic cell, before they are released from the gland, they break down the pancreas itself causing acute pancreatitis. This is a painful disease that ranges from a mild and autolimited process to a severe and lethal condition. Recently, we demonstrated that the pancreatic acinar cell is able to switch on a refined mechanism that could explain the autolimited form of the disease. This is a novel selective form of autophagy named zymophagy, a cellular process to specifically detect and degrade secretory granules containing activated enzymes before they can digest the organ. In this work, we revise the molecules and mechanisms that mediate zymophagy, a selective autophagy of secretory granules. © 2012 Maria I. Vaccaro.

Mancuso A.C.,CONICET | Caselli A.T.,University of Buenos Aires
Sedimentary Geology | Year: 2012

Extensional basins offer a high preservation potential for sedimentary and fossil records. Nonmarine rift basins contain diverse environments, including fluvial and lacustrine. Lake deposits have long been recognized as significant archives of the paleoenvironmental record. The Ischigualasto-Villa Unión Basin represents the only nearly continuous continental Triassic record with up to 6000 m of alluvial, fluvial, and lacustrine deposits. The deep lacustrine interval is known as the Los Rastros Formation and consists of several lacustrine-deltaic cycles. A detailed facies analysis allowed the characterization of five facies associations and two types of cycles: (1) a shoreline-dominated, progradational Type I cycle containing Facies association A (offshore lacustrine deposits) and Facies association B (marginal palustrine deposits along the shoreline of the lake) or Facies association C (lacustrine siliciclastic coastal deposits) and (2) a delta-dominated, progradational Type II cycle characterized by Facies association A (offshore lacustrine and prodelta deposits), Facies association D (delta front deposits), and Facies association E (delta plain deposits). The sedimentary evolution of the Chañares-Los Rastros sequence is defined within this extensional setting as one depositional sequence with three system tracts (lowstand, transgressive, and highstand system tract). Biotic, abiotic, and sedimentologic data allowed the interpretation of the limnologic dynamics of the Los Rastros paleolake as a deep freshwater lake within a half-graben, exhibiting meromixis, and showing a change from moderate eutrophic conditions with low oxygen content to relatively oxygenated oligotrophic conditions. The successive fluctuations recorded in lake level are considered in the sequence stratigraphic framework of Bohacs et al. to reflect the relative balance of sediment and water input versus accommodation in an overfilled lacustrine basin. © 2012 Elsevier B.V. All rights reserved.

Fischbarg J.,University of Buenos Aires
Molecular Aspects of Medicine | Year: 2012

Water is a major component of the eye, and water channels (aquaporins) are ubiquitous in ocular tissues, and quite abundant at their different locations. AQP1 is expressed in corneal endothelium, lens epithelium, ciliary epithelium, and retinal pigment epithelium. AQP3 is expressed in corneal epithelium, and in conjunctival epithelium. AQP4 is expressed in ciliary epithelium and retinal Muller cells. AQP5 is expressed in corneal epithelium, and conjunctival epithelium. AQP0 is expressed in lens fiber cells. It is known that five ocular tissues transport fluid, namely: (1) Corneal endothelium; (2) Conjunctival epithelium; (3) Lens epithelium; (4) Ciliary epithelium; (5) Retinal pigment epithelium. For the corneal endothelium, aquaporins are not the main route for trans-tissue water movement, which is paracellular. Instead, we propose that aquaporins allow fast osmotic equilibration of the cell, which is necessary to maintain optimal rates of fluid movement since the cyclic paracellular water transfer mechanism operates separately and tends to create periodic osmotic imbalances (τ ∼ 5 s). © 2012 Elsevier Ltd. All rights reserved.

Luduena L.,University of the Sea | Vazquez A.,University of Buenos Aires | Alvarez V.,University of the Sea
Carbohydrate Polymers | Year: 2012

This study was based on the influence of lignocellulosic fillers and content on the morphology, crystallization behavior and thermal, mechanical and barrier properties of fully biodegradable eco-composites based on polycaprolactone for packaging applications. The biodegradation in soil as a function of time was also analyzed. Composites with 5 and 15 wt% of cotton (CO); cellulose (CE) and hydrolyzed-cellulose (HCE) were prepared by melt-mixing. It was determined that, whereas lower content of CO and CE produced a decrease on the crystallinity of the matrix, HCE did not affect it. Increasing the filler content, the crystallinity degree of the matrix decreased at less extent, which was independent on the filler type. A clear reduction on the theoretical melting point, attributed to heterogeneous nucleation sites, took place for the lower content of CO and CE. Induction and half-crystallization times diminished when fillers were incorporated but the effect was less notorious at higher filler contents. All fillers enhanced the Young's modulus of the matrix but the optimal mechanical properties were not obtained with HCE, as was expected, but with CE. After analyzing the main parameters that affect the mechanical properties of the composite; such as morphology, hydrophilicity, crystallinity, mechanical properties and thermal stability of the fillers themselves, interface interaction, filler dispersion and thermal aspects of the composites, we concluded that the parameters responsible for such behavior were the larger aspect ratio, better dispersion and enhanced interface interaction of the CE filler. These parameters also affected the barrier properties and the process of biodegradation in soil of the composites. © 2011 Elsevier Ltd. All Rights Reserved.

Gutierrez D.E.,University of Buenos Aires
Environmental Ethics | Year: 2012

Unlike Columbian environmental philosophy, which achieves a certain degree of unity because of the influence of the writings of Augusto Angel-Maya, Argentinean environmental philosophy is more diverse and represents a panorama of views and approaches. Nevertheless, although they could not be said to be environmental philosophy as such, the writings of Rodolfo Kusch could make a significant contribution to environmental thought strongly anchored in the peculiarities of our culture. Alicia Irene Bugallo has worked on themes of ecophilosophy, and has introduced these themes to young people, educators, and the general public. Alcira Bonilla has introduced a type of eco-ethical humanism, avoiding physiocentrism or the sacralization of nature while moving away from anthropocentrism. Unlike Bugallo and Bonilla, whose positions are close to deep ecology, María Julia Bertomeu has emphasized the necessity of normative clarification of generalizable rules oriented toward environmental protection. The Marina Vilte School of the Confederation of Education Workers of the Argentine Republic has been an authentic catalyst by educating a new generation of educators in Argentina with a focus on environmental themes. A collaborative group of intellectuals working on critical thinking, created the journal Theomai, led by its coordinator Guido Galafassi, has elaborated a critique of our existing socio-environmental situation. With regard to the mass media, Miguel Grinberg and Antonio Brailovsky for several decades have been important in spreading concerns about environmental issues.

Epele M.E.,University of Buenos Aires
Anthropology and Medicine | Year: 2016

Based on ethnographic research carried out in the Buenos Aires Metropolitan Area, this paper examines the views of social actors on the psychoanalytically-oriented psychotherapy focused on marginalized populations. From Foucault's perspective on the forms of truth-telling, the aim of this paper is to analyze, as a preliminary research report, treatments according to the native ways of speaking and listening, which dominate the description of therapeutic experiences of patients who come to the treatment without any professional intermediation. The neoliberal transformations of the past decades in Argentina changed both the landscape of the public health system and the daily lives of marginalized people. Considering such changes, this paper examines the ways in which verbal actions (speaking and listening) take place in psychotherapy and mark the course not only of treatments but also the temporal rhythms of their development, and their various levels of efficacy. Finally, the discussion focuses on how ways of speaking and listening in treatments are modeled not only by institutional dynamics but also by the characteristics these verbal activities take in everyday life under the logics of power that prevail over them. © 2016 Informa UK Limited, trading as Taylor & Francis Group

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.

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.

Simeone C.,University of Buenos Aires
International Journal of Modern Physics D | Year: 2012

We prove the impossibility of cylindrical thin-shell wormholes supported by matter satisfying the energy conditions everywhere, under reasonable assumptions about the asymptotic behavior of the in general differentmetrics at each side of the throat. Besides, we establish necessary conditions for the possibility of non-exotic thin-shell wormholes. © 2012 World Scientific Publishing Company.

Capuzzi P.,University of Buenos Aires | Capuzzi P.,CONICET | Gattobigio M.,CNRS Non-Linear Institute of Nice | Vignolo P.,CNRS Non-Linear Institute of Nice
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2011

We study the formation of Faraday waves in an elongated Bose-Einstein condensate in the presence of a one-dimensional optical lattice. The waves are parametrically excited by modulating the radial confinement of the condensate close to a transverse breathing mode of the system. For very shallow optical lattices, phonons with a well-defined wave vector propagate along the condensate, as in the absence of the lattice, and we observe the formation of a Faraday pattern. We find that by increasing the potential depth the local sound velocity decreases, and when it equals the condensate local phase velocity, the condensate develops an incoherent superposition of several modes and the parametric excitation of Faraday waves is suppressed. © 2011 The American Physical Society.

Vazquez G.H.,University of Buenos Aires
Canadian Journal of Psychiatry | Year: 2014

Clinical psychiatric evaluations of patients have changed dramatically in recent decades. Both initial assessments and follow-up visits have become brief and superficial, focused on searching for categorical diagnostic criteria from checklists, with limited inquiry into patient-reported symptomatic status and tolerability of treatments. The virtually exclusive therapeutic task has become selecting a plausible psychotropic, usually based on expert consensus guidelines. These guidelines and practice patterns rest mainly on published monotherapy trials that may or may not be applicable to particular patients but are having a profound impact, not only on modern psychiatric practice but also on psychiatric education, research, and theory.

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.

Goday C.,CSIC - Biological Research Center | Pigozzi M.I.,University of Buenos Aires
Chromosoma | Year: 2010

In the zebra finch (Taeniopygia guttata) a germline-restricted chromosome (GRC) is regularly present in males and females. While the GRC is euchromatic in oocytes, in spermatocytes this chromosome is cytologically seen as entirely heterochromatic and presumably inactive. At the end of male meiosis, the GRC is eliminated from the nucleus. By immunofluorescence on microspreads, we investigated HP1 proteins and histone modifications throughout male meiotic prophase, as well as in young spermatid stages after the GRC elimination. We found that in prophase spermatocytes the GRC chromatin differs from that of the regular chromosome complement. The GRC is highly enriched in HP1β and exhibits high levels of di- and tri-methylated histone H3 at lysine 9 and tri- and di-methylated histone H4 at lysine 20. The GRC does not exhibit neither detectable levels of di- and tri-methylated histone H3 at lysine 4 nor acetylated histone H4 at lysine 5 and 8. The results prove the heterochromatic organization of the GRC in male germline and strongly suggest its transcriptional inactive state during male prophase. Following elimination, in young spermatids the GRC lacks HP1β signals but maintains high levels of methylated histone H3 at lysine 9 and methylated histone H4 at lysine 20. The release of HP1 from the GRC with respect to its elimination is discussed. © 2010 Springer-Verlag.

Moreno I.,University Miguel Hernandez | Iemmi C.,University of Buenos Aires | Campos J.,Autonomous University of Barcelona | Yzuel M.J.,Autonomous University of Barcelona
Optics Express | Year: 2011

We present a Jones matrix method useful to analyze coherent optical Fourier processors employing structured polarization. The proposed method is a generalization of the standard classical optical Fourier transform processor, but considering vectorial spatial functions with two complex components corresponding to two orthogonal linear polarizations. As a result we derive a Jones matrix that describes the polarization output in terms of two vectorial functions defining respectively the structured polarization input and the generalized polarization impulse response. We apply the method to show and analyze an experiment in which a regular scalar diffraction grating is converted into equivalent polarization diffraction gratings by means of an appropriate polarization filtering. The technique is further demonstrated to generate arbitrary structured polarizations. Excellent experimental results are presented. © 2011 Optical Society of America.

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.

Grinberg H.,University of Buenos Aires
Physics Letters, Section A: General, Atomic and Solid State Physics | Year: 2010

An intensity dependent nonlinear coupling model of a two-level system interacting with a bimodal cavity field via two-photon transitions is investigated in a scenario where the rotating wave approximation is lifted. The model is numerically tested against simulations of normal squeezing variance and entropy squeezing factors based on the Heisenberg uncertainty principle and Shannon information theory derived from entangled states. © 2010 Elsevier B.V. All rights reserved.

Alessandro A.P.,University of Buenos Aires
Atmosfera | Year: 2014

In southern South America and for the period 1960-2011, frequencies and trends of seasonal blocking situations (Bs) determined at 100, 70 and 40° W (B100, B70 and B40), respectively are estimated. The effect of such situations on temperature and precipitation is also analyzed. The distribution of occurrences of B100, B70 and B40 peaks in spring and has minimum values in summer; trends are positive in summer and fall and negative in winter and spring. To the north of approximately 38° S, B70 determines negative temperature anomalies (DT) over the entire country during the four seasons and B40 in spring and summer. Except for summer, rainfall is greater than normal when Bs occur at both longitudes. To the south of approximately 38° S, B100 give place to negative δT. The frequencies and amounts of precipitation are greater in spring. This area is limited to the northernmost northern (southernmost southern) area in fall (summer). According to the signs of the trends of the Bs and to the associated values of temperature and precipitation, the way in which they may have contributed to the change in both variables during 1960-2011 is inferred.

Guardia Clausi M.,University of Buenos Aires
ASN neuro | Year: 2010

We have previously demonstrated that aTf (apotransferrin) accelerates maturation of OLs (oligodendrocytes) in vitro as well as in vivo. The purpose of this study is to determine whether aTf plays a functional role in a model of H/I (hypoxia/ischaemia) in the neonatal brain. Twenty-four hours after H/I insult, neonatal rats were intracranially injected with aTf and the effects of this treatment were evaluated in the CC (corpus callosum) as well as the SVZ (subventricular zone) at different time points. Similar to previous studies, the H/I event produced severe demyelination in the CC. Demyelination was accompanied by microglial activation, astrogliosis and iron deposition. Ferritin levels increased together with lipid peroxidation and apoptotic cell death. Histological examination after the H/I event in brain tissue of aTf-treated animals (H/I aTF) revealed a great number of mature OLs repopulating the CC compared with saline-treated animals (H/I S). ApoTf treatment induced a gradual increase in MBP (myelin basic protein) and myelin lipid staining in the CC reaching normal levels after 15 days. Furthermore, significant increase in the number of OPCs (oligodendroglial progenitor cells) was found in the SVZ of aTf-treated brains compared with H/I S. Specifically, there was a rise in cells positive for OPC markers, i.e. PDGFRα and SHH(+) cells, with a decrease in cleaved-caspase-3(+) cells compared with H/I S. Additionally, neurospheres from aTf-treated rats were bigger in size and produced more O4/MBP(+) cells. Our findings indicate a role for aTf as a potential inducer of OLs in neonatal rat brain in acute demyelination caused by H/I and a contribution to the differentiation/maturation of OLs and survival/migration of SVZ progenitors after demyelination in vivo.

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.

Zelaya D.G.,University of Buenos Aires
American Malacological Bulletin | Year: 2015

Bivalves are one of the most abundant groups of invertebrates in many benthic communities. From 1817 to date, numerous contributions have dealt with the Argentine fauna of marine bivalves. Despite this, at present, there is no a text summarizing the currently available information on this group in Argentine waters. The present contribution aims to provide a synthesis of the current state of knowledge of systematics, geographic distribution, biology, and ecology of the living marine and estuarine species of bivalves from the Argentine coast and its shelf and, based on this information, to analyze the species diversity of these areas. For that, 225 publications, including results of scientific expeditions, systematic revisions, description of new species, new distributional records, checklists, compilations on the diversity for particular areas, and contributions dealing with biological and ecological information, were surveyed. As part of this study, 277 nominal species of bivalves were found reported for the study area, although only 169 of them are currently regarded as valid. The analysis of the available bibliography makes evident that the Argentine bivalves have been overlooked throughout the years. This fact results in several limitations and gaps in the current knowledge of this fauna, which are highlighted in the present revision.

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.

Figallo-Orellano A.,University of Buenos Aires
Soft Computing | Year: 2016

Monadic MV-algebras are an algebraic model of first-order infinite-valued Łukasiewicz logic in which only one propositional variable is considered. In this paper, we determine a topological duality for these algebras following well-known P. Halmos’ and H. Priestley’s dualities. © 2016 Springer-Verlag Berlin Heidelberg

Ibarbalz F.M.,CONICET | Figuerola E.L.M.,CONICET | Erijman L.,CONICET | Erijman L.,University of Buenos Aires
Water Research | Year: 2013

Biological degradation of domestic and industrial wastewater by activated sludge depends on a common process of separation of the diverse self-assembled and self-sustained microbial flocs from the treated wastewater. Previous surveys of bacterial communities indicated the presence of a common core of bacterial phyla in municipal activated sludge, an observation consistent with the concept of ecological coherence of high taxonomic ranks. The aim of this work was to test whether this critical feature brings about a common pattern of abundance distribution of high bacterial taxa in industrial and domestic activated sludge, and to relate the bacterial community structure of industrial activated sludge with relevant operational parameters. We have applied 454 pyrosequencing of 16S rRNA genes to evaluate bacterial communities in full-scale biological wastewater treatment plants sampled at different times, including seven systems treating wastewater from different industries and one plant that treats domestic wastewater, and compared our datasets with the data from municipal wastewater treatment plants obtained by three different laboratories. We observed that e. ach industrial activated sludge system exhibited a unique bacterial community composition, which is clearly distinct from the common profile of bacterial phyla or classes observed in municipal plants. The influence of process parameters on the bacterial community structure was evaluated using constrained analysis of principal coordinates (CAP). Part of the differences in the bacterial community structure between industrial wastewater treatment systems were explained by dissolved oxygen and pH. Despite the ecological relevance of floc formation for the assembly of bacterial communities in activated sludge, the wastewater characteristics are likely to be the major determinant that drives bacterial composition at high taxonomic ranks. © 2013 Elsevier Ltd.

Bazin J.,University Pierre and Marie Curie | Batlla D.,University of Buenos Aires | Dussert S.,IRD Montpellier | El-Maarouf-Bouteau H.,University Pierre and Marie Curie | Bailly C.,University Pierre and Marie Curie
Journal of Experimental Botany | Year: 2011

The effect of various combinations of temperature and relative humidity on dormancy alleviation of sunflower seeds during dry after-ripening was investigated. The rate of dormancy alleviation depended on both temperature and embryo moisture content (MC). Below an embryo MC of 0.1 g H2O g -1 dw, dormancy release was faster at 15 °C than at higher temperatures. This suggests that dormancy release at low MC was associated with negative activation energy, supported by Arrhenius plots, and low Q10 values. At higher MC, the rate of dormancy alleviation increased with temperature, correlating well with the temperature dependence of biochemical processes. These findings suggests the involvement of two distinct cellular mechanisms in dormancy release; non-enzymatic below 0.1 g H2O g -1 dw and associated with active metabolism above this value. The effects of temperature on seed dormancy release above the threshold MC were analysed using a population-based thermal time approach and a model predicting the rate of dormancy alleviation is provided. Sunflower embryo dormancy release was effective at temperatures above 8 °C (the base temperature for after-ripening, TbAR, was 8.17 °C), and the higher the after-ripening temperature above this threshold value, the higher was the rate of dormancy loss. Thermodynamic analyses of water sorption isotherms revealed that dormancy release was associated with less bound water and increased molecular mobility within the embryonic axes but not the cotyledons. It is proposed that the changes in water binding properties result from oxidative processes and can, in turn, allow metabolic activities. © 2010 The Author(s).

Silvestroff L.,University of Buenos Aires
ASN neuro | Year: 2013

NSC (neural stem cells)/NPC (neural progenitor cells) are multipotent and self-renew throughout adulthood in the SVZ (subventricular zone) of the mammalian CNS (central nervous system). These cells are considered interesting targets for CNS neurodegenerative disorder cell therapies, and understanding their behaviour in vitro is crucial if they are to be cultured prior to transplantation. We cultured the SVZ tissue belonging to newborn rats under the form of NS (neurospheres) to evaluate the effects of Tf (transferrin) on cell proliferation. The NS were heterogeneous in terms of the NSC/NPC markers GFAP (glial fibrillary acidic protein), Nestin and Sox2 and the OL (oligodendrocyte) progenitor markers NG2 (nerve/glia antigen 2) and PDGFRα (platelet-derived growth factor receptor α). The results of this study indicate that aTf (apoTransferrin) is able to increase cell proliferation of SVZ-derived cells in vitro, and that these effects were mediated at least in part by the TfRc1 (Tf receptor 1). Since OPCs (oligodendrocyte progenitor cells) represent a significant proportion of the proliferating cells in the SVZ-derived primary cultures, we used the immature OL cell line N20.1 to show that Tf was able to augment the proliferation rate of OPC, either by adding aTf to the culture medium or by overexpressing rat Tf in situ. The culture medium supplemented with ferric iron, together with aTf, increased the DNA content, while ferrous iron did not. The present work provides data that could have a potential application in human cell replacement therapies for neurodegenerative disease and/or CNS injury that require the use of in vitro amplified NPCs.

Suarez L.M.,Cajal Institute CSIC | Suarez L.M.,CIBER ISCIII | Solis O.,Cajal Institute CSIC | Solis O.,CIBER ISCIII | And 7 more authors.
Biological Psychiatry | Year: 2014

Background L-3,4-dihydroxyphenylalanine (L-DOPA)-induced dyskinesia is an incapacitating complication of L-DOPA therapy that affects most patients with Parkinson's disease. Previous work indicating that molecular sensitization to dopamine receptor D1 (D1R) stimulation is involved in dyskinesias prompted us to perform electrophysiological recordings of striatal projection "medium spiny neurons" (MSN). Moreover, because enhanced D1R signaling in drug abuse induces changes in spine density in striatum, we investigated whether the dyskinesia is related to morphological changes in MSNs. Methods Wild-type and bacterial artificial chromosome transgenic mice (D1R-tomato and D2R-green fluorescent protein) mice were lesioned with 6-hydroxydopamine and subsequently treated with L-DOPA to induce dyskinesia. Functional, molecular, and structural changes were assessed in corticostriatal slices. Individual MSNs injected with Lucifer-Yellow were detected by immunohistochemistry for three-dimensional reconstructions with Neurolucida software. Intracellular current-clamp recordings with high-resistance micropipettes were used to characterize electrophysiological parameters. Results Both D1R-MSNs and D2R-MSNs showed diminished spine density in totally denervated striatal regions in parkinsonian mice. Chronic L-DOPA treatment, which induced dyskinesia and aberrant FosB expression, restored spine density in D2R-MSNs but not in D1R-MSNs. In basal conditions, MSNs are more excitable in parkinsonian than in sham mice, and excitability decreases toward normal values after L-DOPA treatment. Despite this normalization of basal excitability, in dyskinetic mice, the selective D1R agonist SKF38393 increased the number of evoked action potentials in MSNs, compared with sham animals. Conclusions Chronic L-DOPA induces abnormal spine re-growth exclusively in D2R-MSNs and robust supersensitization to D1R-activated excitability in denervated striatal MSNs. These changes might constitute the anatomical and electrophysiological substrates of dyskinesia. © 2014 Society of Biological Psychiatry.

Different types of alcoholic beverages such as wine and beer were used in ancient times for various medicinal purposes. Being the oldest and probably the most widely used drugs, they were known to have some therapeutic value, in addition to the vital part they played in the daily life of people. Ethanol is produced by fermentation of a variety of plants and consumed either in a diluted form or concentrated by distillation to concoct alcoholic beverages. Beer made of fermented barley is an alcoholic drink that was believed to contain a spirit or a god. It is a drink of relatively low alcohol content with supernatural properties. The same was believed for wine. Considered to be divine, these beverages were the long-sought elixirs of life and appeared in religious ceremonies, in mythology, and in social meals, such as the Greek symposia. In addition, these alcoholic drinks were considered to be a remedy for practically every disease and, therefore, were a common ingredient in ancient prescriptions. They were used as anaesthetics that dull the pain, as stimulants, as analgesics, as antiseptics to cleanse wounds and relieve pain, as emetics, as digestives, as antidotes for plant poisoning, for bites and stings, and as purifiers. However, we should not overlook the harmful effects of alcohol abuse such as drunkenness, chronic liver disease and, in modern terminology, infirmities that included pancreatitis, cardiomyopathy, peripheral neuropathy, dementia, and central nervous system disorders.

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.

Zapiola M.L.,Oregon State University | Zapiola M.L.,University of Buenos Aires | Mallory-Smith C.A.,Oregon State University
Molecular Ecology | Year: 2012

Gene flow is the most frequently expressed public concern related to the deregulation of transgenic events (Snow 2002; Ellstrand 2003). However, assessing the potential for transgene escape is complex because it depends on the opportunities for unintended gene flow, and establishment and persistence of the transgene in the environment (Warwick 2008). Creeping bentgrass (Agrostis stolonifera L.), a turfgrass species widely used on golf courses, has been genetically engineered to be resistant to glyphosate, a nonselective herbicide. Outcrossing species, such as creeping bentgrass (CB), which have several compatible species, have greater chances for gene escape and spontaneous hybridization (i.e. natural, unassisted sexual reproduction between taxa in the field), which challenges transgene containment. Several authors have emphasized the need for evidence of spontaneous hybridization to infer the potential for gene flow (Armstrong 2005). Here we report that a transgenic intergeneric hybrid has been produced as result of spontaneous hybridization of a feral-regulated transgenic pollen receptor (CB) and a nontransgenic pollen donor (rabbitfoot grass, RF, Polypogon monspeliensis (L.) Desf.). We identified an off-type transgenic seedling and confirmed it to be CB × RF intergeneric hybrid. This first report of a transgenic intergeneric hybrid produced in situ with a regulated transgenic event demonstrates the importance of considering all possible avenues for transgene spread at the landscape level before planting a regulated transgenic crop in the field. Spontaneous hybridization adds a level of complexity to transgene monitoring, containment, mitigation and remediation programmes. See also the Perspective by Snow © 2012 Blackwell Publishing Ltd.

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.

Sibbald A.D.,University of Buenos Aires
Otolaryngology - Head and Neck Surgery (United States) | Year: 2012

Acute otitis media has changed conceptually from being a feared infection with severe complications to a modest disease that should be treated for symptomatic relief but often without immediate antimicrobials. This holds true for infants and children with nonsevere forms of the illness if the parents and the clinician agree to a strategy of watchful waiting with easy access for follow-up. Accurate otologic examination is critical for disease recognition, but the initial choice of treatment must also consider the general impact that the disease produces in each individual patient. The appraisal of the symptoms that characterize the illness in a child, matched with the otoscopic intensity of the disease, provide a comprehensive estimation of overall severity that many experts have used for research. The perspectives examined in this article and the schematic construct that proposes considering disease and illness independently may help to bring the current paradigm of acute otitis media into everyday pediatric practice as a model for a more rational and personalized management of each patient. © 2012 American Academy of Otolaryngology - Head and Neck Surgery Foundation.

Daruich J.,University of Buenos Aires
Annals of Hepatology | Year: 2010

Hepatitis C (HCV) is a major public health problem worldwide and it is considered that there are about 180 millions of infected people. The natural history of hepatitis C shows that, of those individuals affected by a primo-infection, 55 to 95% evolve into chronicity. The objective of treatment for chronic hepatitis C is to prevent in the long term the complications and death that this disease may cause. In a short term the most important aim is the sustained virological response (SVR), considered a virological response, normalization of the serum ALT level, histological improvement, improvement in patients' quality of life and the risk of transmission reduction. The association Peginterferon alpha - Ribavirin (PEG IFNα-RBV), at the moment, is the standard of care of patients with chronic hepatitis C and compensated cirrhosis. Two PEG IFNα are licensed, PEG IFNα 2a and PEG IFNα 2b. Pegylation is a procedure that allows the union of polyethylene glycol moieties (PEG) to pharmacologic active proteins; in this case, IFNα. Pegylation of the IFNα 2a and 2b provoke important modifications in these proteins: slower absorption, different distribution, slower elimination, and longer half life with major exposure to the drug and lesser antigenicity. The two pegylated interferons available are dissimilar between them. The SVR in chronic hepatitis C patients who were treated with PEG IFNα-RBV in registration trials was 54 to 61%. Patients with genotypes 1 and 4 must be treated 48 weeks and those with genotypes 2 and 3, 24 weeks. In some situations patients could be treated lesser or longer time. Results obtained from the association of PEG IFNα- RBV - Amantadine in chronic hepatitis C patients are controversial. Meta-analysis comparing both PEG IFNs alpha shows a better SVR with PEG IFNα 2a. Therapies in patients with mild chronic hepatitis C have a similar SVR that those with more advanced liver disease and could be treated in this phase of the disease.

Bou F.,Intel Corporation | Esteva F.,Intel Corporation | Godo L.,Intel Corporation | Rodriguez R.O.,University of Buenos Aires
Journal of Logic and Computation | Year: 2011

This article deals with many-valued modal logics, based only on the necessity operator, over a residuated lattice. We focus on three basic classes, according to the accessibility relation, of Kripke frames: the full class of frames evaluated in the residuated lattice (and so defining the minimum modal logic), the ones evaluated in the idempotent elements and the ones only evaluated in 0 and 1. We show how to expand an axiomatization, with canonical truth-constants in the language, of a finite residuated lattice into one of the modal logic, for each one of the three basic classes of Kripke frames. We also provide axiomatizations for the case of a finite MV chain but this time without canonical truth-constants in the language. © 2009 The Author.

Cymberknop L.J.,University of Buenos Aires
Conference proceedings : ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Conference | Year: 2012

Arterial stiffening is a common but highly variable disorder. Additionally, excessive arterial pulsatility is associated with various common diseases of aging and hypertension. Fractal dimension (FD) quantifies the time series complexity defined by its geometrical representation. Arterial pressure and diameter time series were evaluated in order to assess the relationship between arterial stiffness and FD. Three Corriedale male sheep were operated. Left anterior descending artery (LAD) was dissected and the external arterial diameter was measured trough sonomicrometry. Similarly, a pressure microtransducer was positioned in the upper third of the ascending aorta. Simultaneous pressure and diameter were measured in normal state and under smooth muscle activation. Each time series FD were assessed by the application of Higuchi's method while arterial wall elastic modulus was evaluated by means of the pressure-strain relationship. Coronary stiffness was increased from normal state to phenylephrine state (47.32%, 21.12%, 10.87%) while aortic pressure FD was decreased (2.11%, 2.57%, 6.85%), respectively. Acute hypertension induced by phenylephrine produces an increase in the coronary wall elastic modulus with a concomitant decrease in the fractal nature of the aortic pressure, suggesting that coronary stiffening is associated with an unwrinkled aortic pressure.

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.

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.

Pinto P.T.,University of Buenos Aires | Pinto P.T.,Michigan State University | Litchman E.,Michigan State University
Oikos | Year: 2010

Nitrogen-fixers can contribute significant amounts of nitrogen (N) and impact ecosystem functioning in diverse aquatic and terrestrial ecosystems. What determines N-fixer abundance still remains poorly understood. Here we experimentally investigate major environmental controls on the abundance of N-fixers: nitrogen to phosphorus (N:P) ratio and light. We grew a N-fixer, cyanobacterium Anabaena flos-aquae, in a multispecies community of freshwater phytoplankton in replicated factorial design treatments with two N:P ratios and two light levels. We show that low N:P ratios promote the dominance of the N-fixer in the community, but only under high light. Under low light, N:P ratio did not have a significant effect on the abundance of the N-fixer. N fixation occurred at low N:P only and increased with increasing light. In contrast, the density of non N-fixing cyanobacteria did not depend on N:P ratios. Green algae dominated under high N:P and high light only, exhibiting the opposite pattern of dominance to N-fixers. These results are consistent with patterns observed in nature and help explain the N-fixer distribution along the environmental gradients of nutrients and light. © 2009 The Authors. Journal compilation © 2010 Oikos.

Galigniana M.D.,University of Buenos Aires
Chemistry and Biology | Year: 2012

In this issue of Chemistry & Biology, Grossman et al. report a study on aldosterone-dependent nuclear translocation of the mineralocorticoid receptor (MR). They analyze the dependency of MR retrotransport, DNA-binding, and transcriptional activity on Hsp90 and demonstrate that MR dimerization is a nuclear event. © 2012 Elsevier Ltd All rights reserved.

Poodts E.,University of Bologna | Poodts E.,University of Buenos Aires | Minak G.,University of Bologna | Zucchelli A.,University of Bologna
Composite Structures | Year: 2013

Glass fiber reinforced plastic (GFRP) composite material is often utilized in marine applications for the construction of boats and ships. In this application it is a usual procedure to protect the material with a layer of gel-coat, but if the gel-coat breaks the material would be in direct contact with a humid environment. The main objective of this study was to understand the degradation that sea-water causes on GFRP mechanical properties. The article deals with two common resin systems in marine applications, i.e. polyester and vinylester, and reports the results of quasi-static and vibration tests at different sea-water exposure times, and fatigue tests in dry and wet environments of unexposed specimens and specimens aged in sea water for 22-weeks. The results show degradation of the material in terms of ultimate stress in the case of quasi-static loading, and no appreciable degradation on the fatigue loading case. Vibration tests demonstrated a stable flexural modulus during the water exposure period. © 2012 Elsevier Ltd.

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.

Quarleri J.,University of Buenos Aires
World Journal of Gastroenterology | Year: 2014

The core promoter (CP) of the viral genome plays an important role for hepatitis B virus (HBV) replication as it directs initiation of transcription for the synthesis of both the precore and pregenomic (pg) RNAs. The CP consists of the upper regulatory region and the basal core promoter (BCP). The CP overlaps with the 3′-end of the X open reading frames and the 5′-end of the precore region, and contains cis -acting elements that can independently direct transcription of the precore mRNA and pgRNA. Its transcription regulation is under strict control of viral and cellular factors. Even though this regulatory region exhibits high sequence conservation, when variations appear, they may contribute to the persistence of HBV within the host, leading to chronic infection and cirrhosis, and eventually, hepatocellular carcinoma. Among CP sequence variations, those occurring at BCP may dysregulate viral gene expression with emphasis in the hepatitis B e antigen, and contribute to disease progression. In this review these molecular aspects and pathologic topics of core promoter are deeply evaluated. © 2014 Baishideng Publishing Group Co., Limited. All rights reserved.

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..

Aguilar S.,University of Buenos Aires
Review of European, Comparative and International Environmental Law | Year: 2013

This article addresses the growing body of work within the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) on the management of commercially valuable timber and fish species. The article reviews the types of regulatory tools CITES has adopted to manage fish and timber species subject to high levels of commercial international trade. Tools identified are described through examples from the CITES acquis, and assessed according to two criteria: their normative content to determine the strength of the tool within the CITES regulatory context; and their proactive potential to determine whether the tool is mainly used to achieve the Convention's traditional supportive role towards national management authorities, or for a more modern role as a generator and driving force for sustainable management decisions. © 2013 John Wiley & Sons Ltd.

Chimento L.P.,University of Buenos Aires
AIP Conference Proceedings | Year: 2012

We introduce an effective one-uid description of the interacting dark sector in a spatially at Friedmann-Robertson-Walker space-time and investigate the stability of the power-law solutions. We find the "source equation" for the total energy density and determine the energy density of each dark component. We study linear and nonlinear interactions which depend on the dark matter and dark energy densities, their first derivatives, the total energy density with its derivatives up to second order and the scale factor. We solve the evolution equations of the dark components for both interactions, examine exhaustively several examples and show cases where the problem of the coincidence is alleviated. We show that a generic nonlinear interaction gives rise to the "relaxed Chaplygin gas model" whose effective equation of state includes the variable modified Chaplygin gas model while some others nonlinear interactions yield de Sitter and power-law scenarios. © 2012 American Institute of Physics.

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.

Canepa G.E.,CONICET | Degese M.S.,University of Buenos Aires | Budu A.,University of Sao Paulo | Garcia C.R.S.,University of Sao Paulo | Buscaglia C.A.,CONICET
Biochemical Journal | Year: 2012

TSSA (trypomastigote small surface antigen) is a polymorphic mucin-like molecule displayed on the surface of Trypanosoma cruzi trypomastigote forms. To evaluate its functional properties, we undertook comparative biochemical and genetic approaches on isoforms present in parasite stocks from extant evolutionary lineages (CL Brener and Sylvio X-10). We show that CL Brener TSSA, but not the Sylvio X-10 counterpart, exhibits dosedependent and saturable binding towards non-macrophagic cell lines. This binding triggers Ca 2+ -based signalling responses in the target cell while providing an anchor for the invading parasite.Accordingly, exogenous addition of either TSSA-derived peptides or specific antibodies significantly inhibits invasion of CL Brener, but not Sylvio X-10, trypomastigotes. Non-infective epimastigote forms, which do not express detectable levels of TSSA, were stably transfected with TSSA cDNA from either parasite stock. Although both transfectants produced a surfaceassociated mucin-like TSSA product, epimastigotes expressing CL Brener TSSA showed a ∼2-fold increase in their attachment to mammalian cells. Overall, these findings indicate that CL Brener TSSA functions as a parasite adhesin, engaging surface receptor(s) and inducing signalling pathways on the host cell as a prerequisite for parasite internalization. More importantly, the contrasting functional features of TSSA isoforms provide one appealing mechanism underlying the differential infectivity of T. cruzi stocks. © The Authors Journal compilation © 2012 Biochemical Society.

This article analyzes the creation of the occupational therapy degree in Argentina. Privileging socio-historical construction, it examines aspects of the professionalization process, establishing relationships between the context of the 1956 poliomyelitis epidemic and the influence of gender concepts in the creation of the profession of occupational therapist. The rise of this profession in Argentina introduced the idea of curing by doing, a therapeutic approach that involved doing things as a way of mitigating the consequences of this crucial epidemic. Finally, it suggests an ongoing process of struggle and tensions with obstacles yet to be overcome in order to acquire professional autonomy and a monopoly in practice.

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.

Capitelli N.A.,University of Buenos Aires
Computational Geometry: Theory and Applications | Year: 2016

We introduce the non-pure versions of simplicial balls and spheres with minimum number of vertices. These are a special type of non-homogeneous balls and spheres (NH-balls and NH-spheres) satisfying a minimality condition on the number of facets. The main result is that minimal NH-balls and NH-spheres are precisely the simplicial complexes whose iterated Alexander duals converge respectively to a simplex or the boundary of a simplex. © 2016 Elsevier B.V. All rights reserved.

Mastroleo I.,University of Buenos Aires
Developing World Bioethics | Year: 2016

The general aim of this article is to give a critical interpretation of post-trial obligations towards individual research participants in the Declaration of Helsinki 2013. Transitioning research participants to the appropriate health care when a research study ends is a global problem. The publication of a new version of the Declaration of Helsinki is a great opportunity to discuss it. In my view, the Declaration of Helsinki 2013 identifies at least two clearly different types of post-trial obligations, specifically, access to care after research and access to information after research. The agents entitled to receive post-trial access are the individual participants in research studies. The Declaration identifies the sponsors, researchers and host country governments as the main agents responsible for complying with the post-trial obligations mentioned above. To justify this interpretation of post-trial obligations, I first introduce a classification of post-trial obligations and illustrate its application with examples from post-trial ethics literature. I then make a brief reconstruction of the formulations of post-trial obligations of the Declaration of Helsinki from 2000 to 2008 to correlate the changes with some of the most salient ethical arguments. Finally I advance a critical interpretation of the latest formulation of post-trial obligations. I defend the view that paragraph 34 of ‘Post-trial provisions’ is an improved formulation by comparison with earlier versions, especially for identifying responsible agents and abandoning ambiguous ‘fair benefit’ language. However, I criticize the disappearance of ‘access to other appropriate care’ present in the Declaration since 2004 and the narrow scope given to obligations of access to information after research. © 2015 John Wiley & Sons Ltd.

Leon G.,University of Buenos Aires | Sudarsky D.,National Autonomous University of Mexico
Journal of Cosmology and Astroparticle Physics | Year: 2015

The statistical properties of the primordial density perturbations has been considered in the past decade as a powerful probe of the physical processes taking place in the early universe. Within the inflationary paradigm, the properties of the bispectrum are one of the keys that serves to discriminate among competing scenarios concerning the details of the origin of cosmological perturbations. However, all of the scenarios, based on the conventional approach to the so-called ''quantum-to-classical transition'' during inflation, lack the ability to point out the precise physical mechanism responsible for generating the inhomogeneity and anisotropy of our universe starting from and exactly homogeneous and isotropic vacuum state associated with the early inflationary regime. In past works, we have shown that the proposals involving a spontaneous dynamical reduction of the quantum state provide plausible explanations for the birth of said primordial inhomogeneities and anisotropies. In the present manuscript we show that, when considering within the context of such proposals, the characterization of the spectrum and bispectrum turn out to be quite different from those found in the traditional approach, and in particular, some of the statistical features, must be treated in a different way leading to some rather different conclusions. © 2015 IOP Publishing Ltd and Sissa Medialab srl .

Thamnocephalus chacosaltensis, a new species of fairy shrimp, was found in a temporary turbid pond in the Rivadavia Department, Salta province, Argentina (24°13'19.3"S; 62° 52'14.3"W), belonging to the Chaco salteño. The males present a well developed frontal appendage. Their First (FB) and Third (TB) branches show features diagnostic for the species. FB shows three sub-branches; the most proximal one is coiled, lacks spines all along, gradually thins in distal direction and flattens in the distal half; distally, the flattened portion is folded and ends blunt, bearing a small spine at the tip. TB is a broad-based triangular, thin, much flattened and folded outgrowth, with a small spine at the apex. Male genital and abdominal segments lack medio-ventral spines near their posterior margins. Comparisons with the other species of the genus are established. © Copyright 2016 Magnolia Press.

Navarro A.,University of Cadiz | 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.

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.

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.

A pulsed photoacoustic system is used to determine the fluorescence quantum yield of diluted dye solutions in highly scattering media. In order to show its accuracy, the quantum yield of Rhodamine 6G in water and ethanol was calculated. The chemical Fuchsin was utilized as a dye reference because the entire excitation energy is converted into nonradiative relaxation processes. The scattering coefficient of the samples was incremented by using spherical silica particles of different sizes and concentrations. The determined mean values in the studied scattering optical density range (0-3 cm-1) were 0.95 for ethanol and 0.96 for water. These measurements are in excellent agreement with the best literature values. © 2010 Optical Society of America.

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.

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®.

Mancini M.V.,CONICET | Franco N.V.,University of Buenos Aires | Brook G.A.,University of Georgia
Quaternary International | Year: 2013

Pollen and archaeological records from two areas of southern Patagonia, one in the southern part of the Deseado Massif, the other south of Lago Argentino, suggest an important influence of climate on human movements into new areas. Pollen spectra record a significant dry climate throughout the region prior to ca. 12,900cal BP that may correlate with the Antarctic Cold Reversal (ACR) from ca. 14,500 to 12,700cal BP. The earliest archaeological sites date the initial exploration (sensu Borrero, 1994-95) of the Deseado Massif between 13,081 and 12,141cal BP at the time of the Northern Hemisphere Younger Dryas (YD) cold interval (ca. 12,700-11,500cal BP), which in the Southern Hemisphere was a time of gradually increasing temperatures. When humans set foot into the Deseado Massif, vegetation was grass steppe, indicating that conditions were wetter than during the ACR. The area south of Lago Argentino was occupied somewhat later around 11,000cal BP, also when the vegetation changed to grass steppe. As temperatures increased during the early Holocene, forest replaced grass steppe in southwest Santa Cruz. A mix of forest and grass steppe persisted until ca. 9400cal BP, when there was a return to drier conditions as those of today in the Deseado Massif. © 2012 Elsevier Ltd and INQUA.

Filici C.,University of Buenos Aires
Neural Networks | Year: 2010

In this article a method of error estimation for the neural approximation of the solution of an Ordinary Differential Equation is presented. Some examples of the application of the method support the theory presented. © 2010.

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.

Barraza N.R.,University of Buenos Aires
International Journal of Software Engineering and its Applications | Year: 2013

The parameter estimation for the Compound Poisson Software Reliability Model is analyzed. The biased characteristic is considered in order to get better performance. A comparison with the well known Non Homogeneous Software Reliability Models is presented. Several experimental data are used in order to analyze the goodness of fit of both models.

Bedoya O.A.,CONICET | Marques D.,CONICET | Nunez C.,CONICET | Nunez C.,University of Buenos Aires
Journal of High Energy Physics | Year: 2014

We extend the generalized flux formulation of Double Field Theory to include all the first order bosonic contributions to the α′ expansion of the heterotic string low energy effective theory. The generalized tangent space and duality group are enhanced by α′ corrections, and the gauge symmetries are generated by the usual (gauged) generalized Lie derivative in the extended space. The generalized frame receives derivative corrections through the spin connection with torsion, which is incorporated as a new degree of freedom in the extended bein. We compute the generalized fluxes and find the Riemann curvature tensor with torsion as one of their components. All the four-derivative terms of the action, Bianchi identities and equations of motion are reproduced. Using this formalism, we obtain the first order α′ corrections to the heterotic Buscher rules. The relation of our results to alternative formulations in the literature is discussed and future research directions are outlined. © 2014, The Author(s).

The origins and evolution of sperm storage in Brachyura are enigmatic: sperm is either stored in seminal receptacles, accessible via the vulvae on the sixth thoracic sternite, or in spermathecae at the border between the seventh and eighth sternites. Crabs with spermathecae are collectively referred to as "podotremes" while crabs with seminal receptacles belong to the Eubrachyura. The position of gonopores is the primary basis for subdividing the Eurachyura into the Heterotremata (female vulvae + males with coxal gonopores) and Thoracotremata (female vulvae + males with sternal gonopores). We present a hypothesis about the evolution of seminal receptacles in eubrachyuran female crabs and argue that the sternal gonopore has been internalized into chitin-lined seminal receptacles and the vulva is in fact a secondary aperture. The loss of some or all of the ancestral chitinous seminal receptacle lining was linked to ventral migration of the oviduct connection. Male and female strategies are to maximize gamete fertilization. The most important variable for females is sperm supply, enhanced by long-term storage made possible by the seminal receptacle. To maximize their fertilization rates males must adapt to the structure of the seminal receptacle to ensure that their sperm are close to the oviduct entrance. The major evolutionary impetus for female mating strategies was derived from the consequences of better sperm conservation and the structure of the seminal receptacle. The advantages were all to the females because their promiscuity and sperm storage allowed them to produce more genetically variable offspring, thereby enhancing variation upon which natural selection could act. We extend our arguments to Brachyura as a whole and offer a unifying explanation of the evolution of seminal receptacles, comparing them with the spermathecae found in "Podotremata": they were independent solutions to the same problem: maintaining sperm supply during evolutionary carcinization. Explanation of eubrachyuran mating strategies requires analysis of the mating-moulting link, indeterminate vs. determinate growth format and seminal receptacle structure. Two alternatives for each of these characters means that there are eight possible outcomes. Six of these outcomes have been realized, which we term Portunoid, Majoid, Eriphoid, Xanthoid, Cancroid, and Grapsoid-Ocypodoid strategies, respectively. Mapping these characters on to a workable phylogeny (wherein some changes to the seminal receptacle + moulting-mating links are assumed to have occurred more than once) produces the following relationships: Portunoids + Majoids are a sister group to the rest of the Eubrachyura, which fall into two sister groups, Eriphoids + Xanthoids and Cancroids + Grapsoid-Ocypodoids and the "Podotremata" is sister group to all the Eubrachyura. We conclude that what began as a race to be the first to mate was turned on its head to become a race to be last, by the evolutionary changes to the seminal receptacle. Eubrachyuran females were advantaged by greater reproductive autonomy, more opportunity to mate with other males, resulting in more genetically variable progeny and leading to the evolution of much greater taxonomic diversity compared to "podotremes". © 2011 Elsevier GmbH.

Goya A.F.,University of Buenos Aires
Journal of High Energy Physics | Year: 2014

We show that Zwei-Dreibein Gravity (ZDG), a bigravity theory recently proposed by Bergshoeff, de Haan, Hohm, Merbis, and Townsend in ref. [1], admits exact solutions with anisotropic scale invariance. These type of geometries are the three-dimensional analogues of the spacetimes which were proposed as gravity duals for condensed matter systems. In particular, we find Schrödinger invariant spaces as well as Lifshitz spaces with arbitrary dynamical exponent z. We also find black holes that are asymptotically Lifshitz with z = 3, showing that these (non-constant curvature) solutions of New Massive Gravity (NMG) are persistent after the introduction of the infinite tower of higher-curvature terms of ZDG, provided a renormalization of the parameters. Black holes in asymptotically warped Anti-de Sitter spaces are also found. Interestingly, in almost all the geometries studied in this work, the metric associated with the second dreibein turns out to be equivalent, up to a constant global factor, to the first one. This phenomenon has been previously observed in other bigravity theories in asymptotically flat and asymptotically Anti-de Sitter backgrounds. However, for the particular case of the z = 3 Lifshitz black hole, here we found that the second metric corresponds to a different black hole that coincides with the former only in the asymptotic region. In fact, we find a new family of z = 3 black holes that corresponds to a one-parameter deformation of the NMG solution. © 2014 The Author(s).

Renom M.,University of the Republic of Uruguay | Rusticucci M.,University of Buenos Aires | Barreiro M.,University of the Republic of Uruguay
Climate Dynamics | Year: 2011

We analyze changes in the relationship between extreme temperature events and the large scale atmospheric circulation before and after the 1976 climate shift. To do so we first constructed a set of two temperature indices that describe the occurrence of warm nights (TN90) and cold nights (TN10) based on a long daily observed minimum temperature database that spans the period 1946-2005, and then divided the period into two subperiods of 30 years each (1946-1975 and 1976-2005). We focus on summer (TN10) and winter (TN90) seasons. During austral summer before 1976 the interannual variability of cold nights was characterized by a negative phase of the Southern Annular Mode (SAM) with a cyclonic anomaly centered off Uruguay that favoured the entrance of cold air from the south. After 1976 cold nights are associated not with the SAM, but with an isolated vortex at upper levels over South Eastern South America. During austral winter before 1976, the El Niño phenomenon dominated the interannual variability of warm nights through an increase in the northerly warm flow into Uruguay. However, after 1976 the El Niño connection weakened and the variability of warm nights is dominated by a barotropic anticyclonic anomaly located in the South Atlantic and a low pressure center over South America. This configuration also strengthens the northward flow of warm air into Uruguay. Our results suggest that changes in El Niño evolution after 1976 may have played a role in altering the relationship between temperature extreme events in Uruguay and the atmospheric circulation. © 2011 Springer-Verlag.

Due to its late incorporation into the national State, the social, economic and political setting of the Argentine province Tierra del Fuego differed from that of the rest of the national territory. In the construction of dependent otherness, objectifications and representations were imposed by state-related and non-state-related institutions, among other agencies. In this context, the Salesian mission of La Candelaria and Ushuaia's Jail for recidivists stand out as spaces in which biopolitics was concretised. The native population and criminals in Tierra del Fuego were those to be subjugated. The thesis of the extinction of the Indian and the simultaneous exaltation of the criminal as the subject of progress identified the scientific and political mechanisms by which the exclusion of certain social groups (Tierra del Fuego's indigenous population) and the inclusion of others (criminals) were regulated.

Desimone M.P.,CONICET | Gordillo G.,University of Buenos Aires | Simison S.N.,CONICET
Corrosion Science | Year: 2011

The corrosion inhibition mechanism of the N-[2-[(2-aminoethyl)amino]ethyl]-9-octadecenamide on mild steel surface in CO2-saturated 5% NaCl solution has been studied. The inhibition efficiency decreases with increasing temperature. Adsorption of the inhibitor studied is found to follow the Frumkin adsorption isotherm. EIS results show that the mechanism of its corrosion inhibition at concentrations higher than critical micelle concentration is by forming a protective porous bi-layer. The activation energy, thermodynamic parameters and electrochemical results reveal a change in the adsorption mode of the inhibitor studied: the inhibitor could primarily be physically adsorbed at low concentrations, while chemisorption is favoured as concentration increases. © 2011 Elsevier Ltd.

Gonzalez Diaz E.F.,University of Buenos Aires
Revista de la Asociacion Geologica Argentina | Year: 2011

Jorge polanski abandoned previous orientation in geoform studies, more related to primary geographical concepts and, determining their real geomorphological identity, established a before and after in Argentina in the analysis of landscape geoforms. polanski mostly follows the ideas of William morris Davis, and he was in fact one of the leaders of the davisian school in our country. the geomorphological analysis of polanski was based in the relationship between development and landscape evolution with geological structure, replacing old interpretations based on static principles and genetic processes that lack a precise definition. His concept of geomorphic unit explains the development of land morphology as a result of geomorphological processes and geological structure, coinciding in this way with the european concept of morphostructure. polanski recognized the geoforms that characterized the morphostructure of the bloque de san rafael, mendoza province, roughly known or incorrectly interpreted at the time, and characterized the piedmont environment, between the mendoza and Diamante rivers. His large article of 1962 on this topic constituted a milestone reference on geomorphology, introducing new concepts as pediment, pedimentation o exhumed peneplain.

This article describes the volcanic and sedimentary stratigraphy and their associated processes with the Andean deformation during the Late Cretaceous to Late Pliocene. The studied area is located between the Atuel and Barrancas rivers and the Main Cordillera, in southern Mendoza, Argentina. Three tectovolcanosedimentary cycles limited by regional discordances (Inca, Quechua, Pehuenche and Diaguita) are proposed. The first comprises Upper Oligocene to Upper Miocene volcanic and sedimentary units (Roca and Pircala-Coihueco formations and the Volcanic Cycle Molle). The second extends from the Late Oligocene to Late Miocene (Agua de la Piedra Formation and the Huincán Andesites volcanic cycle). Finally, the third cycle ranges from the Late Miocene to Pliocene (Butaló, Pincheiras, Loma Fiera and Rio Diamante formations and La Brea Andesites).

Studer B.,University of Cambridge | Studer B.,University College London | Manes F.,University of Buenos Aires | Humphreys G.,University of Oxford | And 2 more authors.
Cerebral Cortex | Year: 2015

Successful choice under risk requires the integration of information about outcome probabilities and values and implicates a brain network including the ventromedial prefrontal cortex (vmPFC) and posterior parietal cortex (pPAR). Damage to the vmPFC is linked to poor decision-making and increased risk-taking. Electrophysiological and neuroimaging data implicate the pPAR in the processing of reward probability during choice, but the causal contribution of this area has not been established. We compared patients with lesions to the pPAR (n = 13), vmPFC (n = 13), and healthy volunteers (n = 22) on the Roulette Betting Task, a measure of risk-sensitive decision-making. Both lesion groups were impaired in adjusting their bets to the probability of winning. This impairment was correlated with the extent of pPAR, but not vmPFC, damage. In addition, the vmPFC group chose higher bets than healthy controls overall, an effect that correlated with lesion volume in the medial orbitofrontal cortex. Both lesion groups earned fewer points than healthy controls. The groups did not differ on 2 tasks assessing probabilistic reasoning outside of a risk-reward context. Our results demonstrate the causal involvement of both the pPAR and vmPFC in risk-sensitive choice and indicate distinguishable roles of these areas in probability processing and risk appetite. © 2013 The Author. Published by Oxford University Press.

Sundblad V.,CONICET | Croci D.O.,CONICET | Rabinovich G.A.,CONICET | Rabinovich G.A.,University of Buenos Aires
Histology and Histopathology | Year: 2011

Galectin-3 belongs to a family of highly conserved animal lectins characterized by their ability to recognize multiple N-acetyllactosamine sequences, which can be displayed on both N-and O-glycans on cell surface glycoconjugates. Although first identified in macrophages, galectin-3 (also called 'Mac-2, εBP, CBP35 or L-29') has been found to be widely distributed in several tissues and developmental stages where, depending on its extracellular or intracellular localization, it can display a broad diversity of biological functions including immunomodulation, host-pathogen interactions, embryogenesis, angiogenesis, cell migration, wound healing and apoptosis. In spite of the existence of several reviews describing the multifunctional properties of galectin-3, an integrated view of the regulated expression of this glycan-binding protein in different normal tissues is lacking. Here we attempt to summarize and integrate available information on galectin-3 distribution in normal haematopoietic and non-haematopoietic tissues, mainly in adulthood, with only a brief reference to its expression during embryonic stages. In addition, given the multiplicity of biological roles attributed to this protein, a brief description of galectin-3 functions is also included. Understanding how galectin-3 is regulated in normal tissues will contribute to a rational design of approaches aimed at modulating galectin-3 expression and subcellular localization for experimental and therapeutic purposes.

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.

Krause S.,TU Chemnitz | Aramendia P.F.,University of Buenos Aires | Tauber D.,TU Chemnitz | Von Borczyskowski C.,TU Chemnitz
Physical Chemistry Chemical Physics | Year: 2011

Heterogeneous line broadening and spectral diffusion of the fluorescence emission spectra of perylene diimide molecules have been investigated by means of time dependent single molecule spectroscopy. The influence of temperature and environment has been studied and reveals strong correlation to spectral diffusion processes. We followed the freezing of the molecular mobility of quasi free molecules on the surface upon temperature lowering and by embedding into a poly(methyl methacrylate) (PMMA) polymer. Thereby changes of optical transition energies as a result of both intramolecular changes of conformation and external induced dynamics by the surrounding polymer matrix could be observed. Simulations of spectral fluctuations within a two-level system (TLS) model showed good agreement with the experimental findings. © the Owner Societies.

The right to health has been widely recognized in the Argentine courts, however only those who have the ability to access the justice system are able to fully enjoy that right. Therefore traditionally excluded groups, who for different reasons have not been able to make their demands heard in a judicial court, do not benefit from the recognition gained up to this point in the different judicial resolutions. Taking into account these institutionalized unequal practices, this article suggests a model for understanding the right to health truly as a right. A distinction is made between the right to health as a rule (understood as the minimum or essential core of that right) and the right to health as a principle (understood as the periphery of the right). In this way, it is shown how considering the right to health as both a rule and as a principle could offer greater equality in recognition of that right for disadvantaged groups that lack access to the justice system.

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.

Apesteguia S.,Maimonides 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.

Battista F.,University of Buenos Aires
Contemporary Physics | Year: 2014

The miniaturisation of electronic devices has been a well-known trend in engineering over almost 50 years. The technological advancement in the field can now provide an astonishing control of charge transport in mesoscopic structures. Single particle pumping, namely the control in time and space of the flow of an arbitrarily small number of electrons or holes, has been realised in various kind of structure with, in some cases, very high accuracies. The first half of the manuscript provides a brief overview of different experimental realisations of single particle sources. Though these devices allow to minimise charge fluctuations in the charge current, because of Heisenberg’s uncertainty principle, the emitted particles are characterised by energy fluctuations. The consequences of it are of great relevance and presented in the second part of the paper. © 2014, Taylor & Francis.

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.

Exopolysaccharide (EPS) production by Ganoderma lucidum in response to different culture conditions was studied. Cellulose and glucose, in defined media, resulted in the more efficient enhancers of EPS production among the carbon sources tested. In natural media cultures containing glucose and malt extract exhibited a marked increase (up to 29-fold) respect to defined media. Subsequently, high malt extract and glucose concentrations were tested. G. lucidum produced two fractions of EPS, water-soluble and water-insoluble under these culture conditions. The maximum value (15 g L -1) was reached at 21 days in the medium containing 60 g L -1 malt extract and 40 g L -1 glucose. The incomplete utilization of reducing sugars by the fungus in these media suggested that not only did high malt extract and glucose concentrations play a role in EPS production but also the water activity might be involved. A factorial uniform experimental design to test the effect of malt extract, polyethylene glycol (PEG, as water activity depressor), and initial pH on specific EPS production was applied. G. lucidum showed to be a more efficient specific EPS (mg EPS per g mycelium) producer at pH 3.5 in cultures containing the highest PEG and malt extract concentrations. © 2009 Elsevier Ltd.

Noetinger S.,University of Buenos Aires | di Pasquo M.M.,Dr Matteri y Espana
Geologica Acta | Year: 2011

The palynological analysis of the 2548-3628 m interval of the San Antonio x-1 Borehole in northwestern Argentina is presented. The illustrated palynoflora is composed of 96 species represented by diverse palynological groups such as trilete spores and cryptospores (46 species), microplankton (39 species), chitinozoans (7 species), scolecodonts, and some remaining specimens in open nomenclature and as incertae sedis. One new species, Retusotriletes ottonei, is described. Thirty-four species are first records in the Argentinean Devonian. Three assemblages (SA1, SA2, and SA3) are defined based on the presence, absence, or abundance of groups of taxa. The presence of Grandispora protea and Grandispora douglastownense among others in the assemblage SA1 is indicative of a late Emsian to mid-Eifelian age. The concurrence of Acinosporites macrospinosus and A. acanthomammillatus in the assemblage SA2 is indicative of a late Eifelian-mid Givetian and is also supported by the appearance of several other species such as Chomotriletes vedugensis, Dibolisporites farraginis and Biharisporites parviornatus. An early Frasnian age is associated to the assemblage SA3 on the basis of the appearances of Lunulidia micropunctata, Pseudolunulidia laevigata, Verrucosisporites bulliferus and the abundance of Maranhites. The assemblages SA1 and SA2 reflect a nearshore, shallow marine depositional conditions, characterized by a high terrestrial input and variable marine influence, while the assemblage SA3 could represent a transgression during that time. The assemblages are composed of many cosmpolitan index species that support a partial correlation with Brazilian and Euramerican zonations resulting from the effects of paleolatitude and the configuration of land and sea for that time, with a narrow Rheic Ocean between northern Gondwana and Euramerica.

Somoza R.,University of Buenos Aires
Canadian Journal of Earth Sciences | Year: 2011

Determining the Late Cretaceous paleomagnetic pole for North America has been difficult because of the lack of suitable rocks of that age in cratonic areas to provide the necessary data. As an alternative, different studies have appealed to paleomagnetic data from rocks in western North America. Using paleopoles from stable areas in neighboring continents, it is suggested that the available Late Cretaceous paleomagnetic record in western North America should be analyzed in terms of rigid body deformations rather than be used to represent the cratonic reference field.

Martarega guarani sp. n. is described and illustrated from north-eastern Argentina (Misiones Province), based on brachypterous forms of both sexes and macropterous females. Comparisons with its close relative M. uruguayensis are included. The hind femur with a basal notch extending some distance beyond the apex of the trochanter and conspicuous enlargement contiguous to this notch distinguish the female of M. guarani sp. n. from those of all the remaining species of Martarega. The following combination of characters distinguish the male of M. guarani sp. n. from those of all the remaining species of Martarega: total body length less than 6.5 mm; metaxyphus trilobed with median lobe bluntly rounded; hemelytra of brachypterous form opaque with a narrow straight hyaline stripe running medially almost entire length of wing and a second short one at base of the hemelytral process; anterior surface of middle trochanter with a group of cohesive lanceolate setae on a nodule; anterior surface of middle femur without a nodule. An identification key to the brachypterous form of all described species of Martarega is given. The distribution, habitat preferences and association between species of M. guarani sp. n. are presented. © 2011 Taylor & Francis.

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.

Rosabal J.A.,University of Buenos Aires | Rosabal J.A.,CEA Saclay Nuclear Research Center
Journal of High Energy Physics | Year: 2015

Abstract: In this work we revisit the E8× ℝ+ generalised Lie derivative encoding the algebra of diffeomorphisms and gauge transformations of compactifications of M-theory on eight-dimensional manifolds, by extending certain features of the E7× ℝ+ one. Compared to its Ed× ℝ+, d ≤ 7 counterparts, a new term is needed for consistency. However, we find that no compensating parameters need to be introduced, but rather that the new term can be written in terms of the ordinary generalised gauge parameters by means of a connection. This implies that no further degrees of freedom, beyond those of the field content of the E8 group, are needed to have a well defined theory. We discuss the implications of the structure of the E8× ℝ+ generalised transformation on the construction of the d = 8 generalised geometry. Finally, we suggest how to lift the generalised Lie derivative to eleven dimensions. © 2015, The Author(s).

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.

Giribet G.,University of Buenos Aires | Giribet G.,Pontifical Catholic University of Valparaiso
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2013

In a recent paper Emparan et al. [arXiv:1302.6382] studied general relativity in the limit in which the number of spacetime dimensions D tends to infinity. They showed that, in such limit, the theory simplifies notably. It reduces to a theory whose fundamental objects, black holes and black branes, behave as noninteracting particles. Here, we consider a different way of extending gravity to D dimensions. We present a special limit of dimensionally continued gravity in which black holes retain their gravitational interaction at large D and still have entropy proportional to the mass. The similarities and differences with the limit considered in Emparan et al. [arXiv:1302.6382] are discussed. © 2013 American Physical Society.

Radusky L.,University of Buenos Aires
Database : the journal of biological databases and curation | Year: 2014

In 2012 an estimated 8.6 million people developed tuberculosis (TB) and 1.3 million died from the disease [including 320 000 deaths among human immunodeficiency virus (HIV)-positive people]. There is an urgent need for new anti-TB drugs owing to the following: the fact that current treatments have severe side effects, the increasing emergence of multidrug-resistant strains of Mycobacterium tuberculosis (Mtb), the negative drug-drug interactions with certain HIV (or other disease) treatments and the ineffectiveness against dormant Mtb. In this context we present here the TuberQ database, a novel resource for all researchers working in the field of drug development in TB. The main feature of TuberQ is to provide a druggability analysis of Mtb proteins in a consistent and effective manner, contributing to a better selection of potential drug targets for screening campaigns and the analysis of targets for structure-based drug design projects. The structural druggability analysis is combined with features related to the characteristics of putative inhibitor binding pockets and with functional and biological data of proteins. The structural analysis is performed on all available unique Mtb structures and high-quality structural homology-based models. This information is shown in an interactive manner, depicting the protein structure, the pockets and the associated characteristics for each protein. TuberQ also provides information about gene essentiality information, as determined from whole cell-based knockout experiments, and expression information obtained from microarray experiments done in different stress-related conditions. We hope that TuberQ will be a powerful tool for researchers working in TB and eventually will lead to the identification of novel putative targets and progresses in therapeutic activities. Database URL: http://tuberq.proteinq.com.ar/

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.

Sica R.E.P.,University of Buenos Aires
Biocybernetics and Biomedical Engineering | Year: 2012

This article summarizes the pathogenic mechanisms known to be responsible for sporadic amyotrophic lateral sclerosis, such as excitoxicity, endoplasmic reticulum stress, oxidative stress, proteins damage, inflammation, genes abnormalities and neuronal death; some clinical features of the disorder are discussed as well. Finally, it puts forward the hypothesis that astrocytes, rather than the motor neurons, may be the cells initially damaged by the action of a still unknown causal agent, being the neuronal death a consequence of that first insult. The article suggests that an emergent virus, perhaps a retro-virus, or a misfolded infectious protein might be the agent able to accomplish the task.

Postigo A.,University of Buenos Aires
Canadian Journal of Chemistry | Year: 2012

This account intends to cover recent literature on radical perfluoroalkylation reactions of aromatic nuclei in organic and aqueous media. Emphasis will be placed on radical aromatic perfluoroalkylation reactions in water or aqueous media, with the aim of exploring aromatic radical reactivity in a benign environment. © 2012 Published by NRC Research Press.

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.

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.

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.

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.

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.

Salazar A.,University of Miami | Goldstein G.,University of Miami | Goldstein G.,University of Buenos Aires | Franco A.C.,University of Brasilia | Miralles-Wilhelm F.,Florida International University
Journal of Ecology | Year: 2012

Seedling dynamics are crucial for understanding spatial plant distribution patterns, yet little is known about seedling establishment in Neotropical savannas because empirical studies at the community level are scarce. Over 2 years, we studied the recruitment and survival of an initial seedling assemblage and three cohorts of recruits of woody plants within 216 plots of 1 m 2 located along a tree density gradient in the savannas of central Brazil. These savannas differ in tree density and canopy cover, from closed (high canopy cover) to open savannas (low canopy cover), and are located along shallow topographic gradients. We measured community-wide seedling limitation (i.e. proportion of 1-m 2 plots without seedlings of any woody species), photosynthetic photon flux density, litter cover, soil moisture and soil nutrients in each savanna type. Because closed savannas had lower PPFD and higher leaf litter cover than open savannas, we evaluated the effects of light level and litter cover on seedling emergence of nine dominant savanna woody species under controlled conditions in a glasshouse. Density, recruitment and survival of seedlings decreased over time because of mortality in all savanna types, but they were consistently higher in closed than in open savannas. Community-wide seedling limitation was significantly lower in closed (0.16 ± 0.03) than in open (0.30 ± 0.05) savannas. In the glasshouse, high litter cover and very low light levels reduced seedling emergence of most species, suggesting an adaptation to delay seed germination until the wet season when soil water availability is high and leaf litter rapidly decomposes. Synthesis: In Neotropical savannas, tree canopy cover facilitates seedling establishment of woody species by reducing stressful environmental conditions. In particular, low irradiance and high litter cover in closed savannas enhance the recruitment and survival of woody seedlings relative to open savannas by reducing soil water deficits and increasing nutrient availability in the upper soil layers. The higher seedling limitation of tree species in open than in closed savannas contributes to maintain relatively different balances between trees and herbaceous plants along topographic gradients in Neotropical savannas and helps to explain spatial distribution patterns of woody species in these ecosystems. © 2012 The Authors. Journal of Ecology © 2012 British Ecological Society.

Ayus J.C.,Director of Clinical Research | Caputo D.,Hospital Alejandro Posadas | Heguilen R.,Hospital Fernandez | Gonzalez C.D.,University of Buenos Aires | Moritz M.L.,University of Pittsburgh
American Journal of Kidney Diseases | Year: 2015

Background 3% sodium chloride solution is the accepted treatment for hyponatremic encephalopathy, but evidence-based guidelines for its use are lacking. Study Design A case series. Setting & Participants Adult patients presenting to the emergency department of a university hospital with hyponatremic encephalopathy, defined as serum sodium level < 130 mEq/L with neurologic symptoms of increased intracranial pressure without other apparent cause, and treated with a continuous infusion of 500 mL of 3% sodium chloride solution over 6 hours through a peripheral vein. Predictors Hyponatremic encephalopathy defined as serum sodium level < 130 mEq/L with neurologic symptoms of increased intracranial pressure without other apparent cause. Outcomes Change in serum sodium level within 48 hours, improvement in neurologic symptoms, and clinical evidence of cerebral demyelination, permanent neurologic injury, or death within 6 months' posttreatment follow-up. Results There were 71 episodes of hyponatremic encephalopathy in 64 individuals. Comorbid conditions were present in 86% of individuals. Baseline mean serum sodium level was 114.1 ± 0.8 (SEM) mEq/L and increased to 117.9 ± 1.3, 121.2 ± 1.2, 123.9 ± 1.0, and 128.3 ± 0.8 mEq/L at 3, 12, 24, and 48 hours following the initiation of 3% sodium chloride solution treatment, respectively. There was a marked improvement in central nervous system symptoms within hours of therapy in 69 of 71 (97%) episodes. There were 12 deaths, all of which occurred following the resolution of hyponatremic encephalopathy and were related to comorbid conditions, with 75% of deaths related to sepsis. No patient developed neurologic symptoms consistent with cerebral demyelination at any point during the 6-month follow-up period. Limitations Lack of a comparison group and follow-up neuroimaging studies. Number of cases is too small to provide definitive assessment of the safety of this protocol. Conclusions 3% sodium chloride solution was effective in reversing the symptoms of hyponatremic encephalopathy in the emergency department without producing neurologic injury related to cerebral demyelination on long-term follow-up in this case series. © 2015 National Kidney Foundation, Inc.

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.

Gonzalez R.M.,CONICET | Ricardi M.M.,CONICET | Iusem N.D.,CONICET | Iusem N.D.,University of Buenos Aires
Epigenetics | Year: 2013

Tolerance to water deficits was evolutionarily relevant to the conquest of land by primitive plants. In this context, epigenetic events may have played important roles in the establishment of drought stress responses. We decided to inspect epigenetic marks in the plant organ that is crucial in the sensing of drought stress: the root. Using tomato as a crop model plant, we detected the methylated epialleles of Asr2, a protein-coding gene widespread in the plant kingdom and thought to alleviate restricted water availability. We found 3 contexts (CG, CNG, and CNN) of methylated cytosines in the regulatory region of Solanum lycopersicum Asr2 but only one context (CG) in the gene body. To test the hypothesis of a link between epigenetics marks and the adaptation of plants to drought, we explored the cytosine methylation status of Asr2 in the root resulting from water-deficit stress conditions. We found that a brief exposure to simulated drought conditions caused the removal of methyl marks in the regulatory region at 77 of the 142 CNN sites. In addition, the study of histone modifications around this model gene in the roots revealed that the distal regulatory region was rich in H3K27me3 but that its abundance did not change as a consequence of stress. Additionally, under normal conditions, both the regulatory and coding regions contained the typically repressive H3K9me2 mark, which was lost after 30 min of water deprivation. As analogously conjectured for the paralogous gene Asr1, rapidly acquired new Asr2 epialleles in somatic cells due to desiccation might be stable enough and heritable through the germ line across generations, thereby efficiently contributing to constitutive, adaptive gene expression during the evolution of desiccation-tolerant populations or species. © 2013 Landes Bioscience.

Heleno R.,CSIC - Mediterranean Institute for Advanced Studies | Devoto M.,University of Buenos Aires | Pocock M.,University of Bristol
Ecological Indicators | Year: 2012

Recently, the focus of conservation efforts gradually changed from a species-centred approach to a broader ambition of conserving functional ecosystems. This new approach relies on the understanding that much ecosystem function is a result of the interaction of species to form complex interaction networks. Therefore measures summarising holistic attributes of such ecological networks have the potential to provide useful indicators to guide and assess conservation objectives. The most generally accepted insight is that complexity in species interactions, measured by network connectance, is an important attribute of healthy communities which usually protects them from secondary extinctions. An implicit and overlooked corollary to this generalization is that conservation efforts should be directed to conserve highly connected communities. We conducted a literature review to search for empirical evidence of a relationship between connectance (complexity) and conservation value (communities on different stages of degradation). Our results show that the often assumed positive relationship between highly connected and desirable (i.e. with high conservation value) communities does not derive from empirical data and that the topic deserves further discussion. Given the conflicting empirical evidence revealed in this study, it is clear that connectance on its own cannot provide clear information about conservation value. In the face of the ongoing biodiversity crisis, studies of species interaction networks should incorporate the different 'conservation value' of nodes (i.e. species) in a network if it is to be of practical use in guiding and evaluating conservation practice. © 2011 Elsevier Ltd.

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.

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.

Rodriguez J.B.,University of Buenos Aires
Synthesis (Germany) | Year: 2014

Tetraethyl vinylidenebisphosphonate is a versatile synthetic intermediate that allows access to a variety of highly functionalized compounds bearing the bisphosphonic moiety. As an electron-deficient alkene, this compound is able to undergo conjugate addition with a variety of reagents including strong nucleophiles, such as organometallic reagents and enolates, as well as very mild nucleophiles, such as amines, mercaptans and alcohols. The title compound also possesses the ability to behave as a dipolarophile or dienophile in 1,3-dipolar cycloadditions or Diels-Alder reactions, giving rise to five- or six-membered rings containing the bisphosphonic unit. In summary, tetraethyl vinylidenebisphosphonate is a very useful synthon to have at hand for straightforward syntheses of bisphosphonate derivatives of diverse structures. This bisphosphonate moiety has proven to be very important to impart important pharmacological action. 1 Introduction 2 General Reactivity 3 Michael Addition Reactions 3.1 Reaction with Organometallic Reagents 3.2 Reaction with Mercaptans and Amines 3.3 Reaction with Phosphorus-Containing Nucleophiles 3.4 Epoxidation, Loss of a Phosphonate Unit and Rearrangement Reactions 3.5 Michael Reactions with Enolates 4. Cycloaddition Reactions 4.1 Diels-Alder Reactions 4.2 1,3-Dipolar Cycloadditions 4.2.1 Reaction with Diazo Compounds 4.2.2 Reaction with Nitrones 4.2.3 Reaction with Nitrile Oxides 4.2.4 Grigg Azomethine Ylide Cyclizations 4.2.5 Reaction with Azides 5 Concluding Remarks. © Georg Thieme Verlag Stuttgart, New York.

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.

Kokot R.R.,University of Buenos Aires
Revista de la Asociacion Geologica Argentina | Year: 2010

Three of the biggest barrier spits of Argentina are studied in order to determine the relationship between the coastal planform and littoral dynamics. The studied landforms are the spit of Cabo San Antonio of an age of the 5800 years BP, the north spit of Caleta Valdés with a maximum age of approximately 5700 years BP and El Páramo spit of San Sebastián bay with an inferred age of approximately 6000 years BP. The orientation regarding the coastal planform of the three spits, allows to establish the relationship between landforms and coastal dynamics, being obtained the predominant waves that gave origin to them. Also the possible consequences for the modification or erosion of these landforms, that they would take to the disappearance of coastal environments of significant ecological value and the submergence of some adjacent areas; just as it would happen in Caleta Valdés.

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.

Troncoso A.,University of Buenos Aires
Asian Pacific Journal of Tropical Biomedicine | Year: 2016

The Aedes aegypti mosquito which transmits Zika virus (as well as dengue, chikungunya and yellow fever) represents a high risk for global transmission. This virus comes from Africa, the Zika forest in Uganda, where it was discovered in 1947 in a rhesus monkey. In May 2015, the first local cases were recorded in Brazil, surpassing 1.5 million cases in December of the same year. By March 2016, local transmission of Zika was recognized in 34 countries. Its clinical condition is similar to dengue febrile illness, although milder. The final geographical distribution area is constantly expanding. Recently, it has been associated with cases of Guillain-Barré syndrome in Brazil, Colombia, El Salvador, Venezuela and Suriname. Microcephaly was documented in Brazil. This article discusses some factors that contributed to the spread of Zika virus in South America. Climate change associated with the events of the phenomenon of "El Niño" is also analyzed. The biggest concern is how quickly Zika is spreading around the world and that it could be far more dangerous than previously thought. Zika virus infection, by its explosive potential, has every chance of becoming a global pandemic. © 2016 Hainan Medical University.

Lattes R.,Institute Nefrologia Nephrology | Lasala M.B.,University of Buenos Aires
Clinical Microbiology and Infection | Year: 2014

This review addresses relevant aspects of Chagas disease in the immunocompromised host. Chagas disease-one of the world's most neglected diseases-has become a global public health concern. Novel transmission modalities, such as organ transplantation, evidence of parasite persistence in chronically infected individuals-with the potential for reactivation under immunosuppression-and the prolonged survival of immunosuppressed patients call for an appraisal of the disease in this particular setting. The management and outcome of solid organ transplantation in the infected recipient with special focus on heart transplantation is addressed. The guidelines for management and the outcome of the recipients of organs from infected donors are discussed, and comments on haematopoietic stem cell transplantation are included. Finally, Chagas disease in other situations of impairment of the immune system, such as HIV/AIDS and autoimmune diseases, are considered. Immunosuppression has become an increasingly frequent condition that might modify the natural history of Trypanosoma cruzi infection. A number of strategies are available for Chagas disease management in the immunosuppressed patient. First, according to recent recommendations from the health authorities in Argentina, most infected patients would benefit from being treated at diagnosis. This has not been validated for patients with different immunosuppressive disorders. A different strategy would involve treating only patients with documented reactivation (either parasitaemia or clinical manifestations). These different approaches are discussed. To reach a diagnosis of parasitaemia, monitoring is essential, either with conventional methods or with molecular techniques that are not yet available in all centres. Collaborative studies are needed to improve the level of evidence, which will allow for better guidelines. © 2014 European Society of Clinical Microbiology and Infectious Diseases.

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.

del Priore L.,University of Buenos Aires
Cytogenetic and Genome Research | Year: 2015

In the zebra finch, 2 alternative morphs regarding centromere position were described for chromosome 6. This polymorphism was interpreted to be the result of a pericentric inversion, but other causes of the centromere repositioning were not ruled out. We used immunofluorescence localization to examine the distribution of MLH1 foci on synaptonemal complexes to test the prediction that pericentric inversions cause synaptic irregularities and/or crossover suppression in heterozygotes. We found complete suppression of crossing over in the region involved in the rearrangement in male and female heterozygotes. In contrast, the same region showed high levels of crossing over in homozygotes for the acrocentric form of this chromosome. No inversion loops or synaptic irregularities were detected along bivalent 6 in heterozygotes suggesting that heterologous pairing is achieved during zygotene or early pachytene. Altogether these findings strongly indicate that the polymorphic chromosome 6 originated by a pericentric inversion. Since inversions are common rearrangements in karyotypic evolution in birds, it seems likely that early heterologous pairing could help to fix these rearrangements, preventing crossing overs in heterozygotes and their deleterious effects on fertility. © 2015 S. Karger AG, Basel Copyright © 2015, S. Karger AG. All rights reserved.

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.

Acha C.,University of Buenos Aires
Journal of Physics D: Applied Physics | Year: 2011

Studies related to the dynamics of resistive switching (RS) in ceramic YBCO/metal interfaces were performed. The change in interface resistance during the application of square pulses and its current-voltage (I-V) characteristics were measured. The obtained non-linear current dependence of the differential resistance can be very well reproduced by modelling the electrical behaviour of the interface with simple circuit elements. The RS produces defined changes in the parameters of the circuit model that reveal the particular dynamics of the mechanism beneath the resistance change in complex oxide/metal interfaces. © 2011 IOP Publishing Ltd.

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.

Stortz C.A.,University of Buenos Aires
Carbohydrate Research | Year: 2015

The present article shows the objective figures of the contributions of South American research centers to Carbohydrate Research during its 50 years of history, measured in terms of members of the Editorial Board, number of articles and citations to them, together with a country-based comparison, and the progression of these contributions with time. In addition, it also shows the subjective feelings of the author toward the same journal. © 2015 Elsevier Ltd. All rights reserved.

The stratigraphy of the Gran Bajo del Gualicho Formation is explained by the identification of the new Saladar and Arriola Members. The molluscan fauna comprises 38 genera and 44 species, 17 of which are new: Anadara australis sp. nov., Cubitostrea delrioi sp. nov., Amusium rorii sp. nov., Zygochlamys rizzoloi sp. nov., Pododesmus (Monia) atlantica sp. nov., Tawera canalei sp. nov., Dosinia (Dosinia) salarensis sp. nov., 'Spirocolpus' adapicis sp. nov., Torcula magna sp. nov., Magnatica hansi sp. nov., Eudolium lissiei sp. nov., Sconsia magdai sp. nov., Chicoreus (Chicoreus) guadalupei sp. nov., Penion patagonensis sp. nov., Mitra (Fusimitra) carlosi sp. nov., Austroimbricaria brugnii sp. nov. y Polystira cingula sp. nov. The NVG (Nodipecten sp.-Venericor abasolensis- Glycymerita camaronesia) Molluscan Assemblage in the Saladar Member nov. indicates an age of late Early Miocene-earliest Middle Miocene. The Saladar Member correlates with the upper section of the Chenque Formation and with the Venericor bearing horizons of the Gaiman and Vaca Mahuida formations. The fauna of this member constitutes another evidence with respect to the weather stripes stated for Patagonia since the Late Oligocene-Early Miocene. The assemblage recorded in the Arriola Member nov. indicates the probable presence of the Aequipecten parenensis Zone and a stratigraphic relationship with the Puerto Madryn Formation of a Late Miocene age, extending the covered area along the Valdesian Province to the Salinas del Gualicho. The fauna of the Saladar Member shows more affinity with that in the Monte León and Chenque formations, while the fauna in the Arriola Member shares more resemblance with the Paraná and Puerto Madryn formations. The Chilean Navidad and Guadal formations have 30% and 10% of genus in common with fauna of the Saladar Member, respectively. © 2011 Servicio Nacional de Geología y Minería.

De Jager C.,Netherlands Institute for Sea Research | Duhau S.,University of Buenos Aires
Journal of Space Weather and Space Climate | Year: 2012

The solar dynamo is the exotic dance of the sun's two major magnetic field components, the poloidal and the toroidal, interacting in anti-phase. On the basis of new data on the geomagnetic aa index, we improve our previous forecast of the properties of the current Schwabe cycle #24. Its maximum will occur in 2013.5 and the maximum sunspot number Rmax will then be 62 ± 12, which is within the bounds of our earlier forecasts. The subsequent analysis, based on a phase diagram, which is a diagram showing the relation between maximum sunspot numbers and minimum geomagnetic aa index values leads to the conclusion that a new Grand Episode in solar activity has started in 2008. From the study of the natural oscillations in the sunspot number time series, as found by an analysis based on suitable wavelet base functions, we predict that this Grand Episode will be of the Regular Oscillations type, which is the kind of oscillations that also occurred between 1724 and 1924. Previous expectations of a Grand (Maunder-type) Minimum of solar activity cannot be supported. We stress the significance of the Hallstatt periodicity for determining the character of the forthcoming Grand Episodes. No Grand Minimum is expected to occur during the millennium that has just started. © Owned by the authors, Published by EDP Sciences 2012.

Forte M.,University of Buenos Aires
European Physical Journal C | Year: 2016

We define a generalization of scalar fields with non-canonical kinetic term which we call exotic k-essence or, briefly, exotik. These fields are generated by the global description of cosmological models with two interactive fluids in the dark sector and under certain conditions they correspond to usual k-essences. The formalism is applied to the cases of constant potential and of inverse square potential and also we develop the purely exotik version for the modified holographic Ricci type (MHR) of dark energy, where the equations of state are not constant. With the kinetic function F=1+mx and the inverse square potential we recover, through the interaction term, the identification between k-essences and quintessences of an exponential potential, already known for Friedmann–Robertson–Walker and Bianchi type I geometries. Worked examples are shown that include the self-interacting MHR and also models with crossing of the phantom divide line (PDL). © 2016, The Author(s).

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.

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.

Solari C.A.,University of Buenos Aires | Kessler J.O.,University of Arizona | Goldstein R.E.,University of Cambridge
American Naturalist | Year: 2013

The transition from unicellular, to colonial, to larger multicellular organisms has benefits, costs, and requirements. Here we present a model inspired by the volvocine green algae that explains the dynamics involved in the unicellular-multicellular transition using life-history theory and allometry. We model the two fitness components (fecundity and viability) and compare the fitness of hypothetical colonies of different sizes with varying degrees of cellular differentiation to understand the general principles that underlie the evolution of multicellularity. We argue that germ-soma separation may have evolved to counteract the increasing costs and requirements of larger multicellular colonies. The model shows that the cost of investing in soma decreases with size. For lineages such as the Volvocales, as reproduction costs increase with size for undifferentiated colonies, soma specialization benefits the colony indirectly by decreasing such costs and directly by helping reproductive cells acquire resources for their metabolic needs. Germ specialization is favored once soma evolves and takes care of vegetative functions. To illustrate the model, we use some allometric relationships measured in Volvocales. Our analysis shows that the cost of reproducing an increasingly larger group has likely played an important role in the transition to multicellularity and cellular differentiation. © 2013 by The University of Chicago. 0003-0147/2013/18103-54025$15.00. All rights reserved.

Minuto Espil M.,University of Buenos Aires
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) | Year: 2012

The support and confidence of association rules are defined in terms of itemset frequencies. While deciding the satisfiability of a set of itemset frequencies is known to be an NPTIME complete problem when frequencies are specified through rational ranges, this complexity result is too wide. To achieve tractability, two simpler problems are studied, instead. Both receive a set of association rules as input, each rule provided with exact support and confidence values, and the decision is to be made, respectively on the consistency of the addition and on the implication of a goal rule. Both allow bounds for the support and confidence values of the goal to be specified, and only admit itemsets relevant to the rules to have non-empty extensions in a model. We show that the problems are tractable and efficient algorithms for them are presented. © 2012 Springer-Verlag.

Luduena L.N.,University of the Sea | Vazquez A.,University of Buenos Aires | Alvarez V.A.,University of the Sea
Journal of Applied Polymer Science | Year: 2013

The effect of addition of unmodified (CNa+) and modified (C30B and C20A) montmorillonites on the performance of polycaprolactone (PCL) based nanocomposites prepared by melt intercalation was studied. The study covers morphological and thermal aspects, mechanical and barrier properties and also biodegradability, which are important for packaging applications. Particular effort was made to find the main characteristics of the clays responsible for the final clay dispersion degree inside the nanocomposite. The most hydrophobic reinforcement (demonstrated by water adsorption tests) also showed the strongest thermal stability (shown by thermogravimetrical analysis) and the larger basal spacing (calculated by X-ray diffractometry (XRD)), which were the main characteristics that led to the best clay dispersion degree inside the PCL matrix (demonstrated by XRD and Transmission Electron Microscopy (TEM)). The findings demonstrate that a biodegradable polymer/clay nanocomposite with enhanced mechanical, impact, and barrier properties was obtained. © 2012 Wiley Periodicals, Inc.

Pereira C.A.,University of Buenos Aires
Infectious Disorders - Drug Targets | Year: 2014

Trypanosomatids parasites have complex life cycles which involve a wide diversity of milieus with very different physicochemical properties. Arginine kinase is one of the key enzymes, responsible for the parasites’ metabolic plasticity, which maintains the cell energy homeostasis during environment changes. Arginine kinase catalyzes the reversible phosphorylation between phosphoarginine and ADP. The phosphagen phosphoarginine sustains high levels of cellular activity until metabolic events, such as glycolysis and oxidative phosphorylation, are switched on. In different unicellular and multicellular organisms including trypanosomatids, it was demonstrated that arginine kinase is an important component in resistance mechanisms to different stress factors, such as reactive oxygen species, trypanocidal drugs, pH and starvation. In addition, few arginine kinase inhibitors were identified during the lasts years, some of them with trypanocidal activity, such as polyphenolic compounds. All these unique features, in addition to the fact that arginine kinase is completely absent in mammals, make this pathway a favorable start point for rational drug design for the treatment of human trypanosomamiases. © 2014 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.

Yuhjtman S.A.,University of Buenos Aires
Journal of Statistical Physics | Year: 2015

We show that the stability constant of the Lennard-Jones potential in (Formula presented.), is smaller than 14.316. This is remarkably smaller than the best previously known bound. Our method is very elementary, and probably applicable to other similar potentials such as the Morse potentials. We also improve slightly, in the Lennard-Jones case, the lower bound for the minimum interparticle distance of an optimal n-particle configuration to 0.684. © 2015, Springer Science+Business Media New York.

Sorroche F.G.,National University of Rio Cuarto | Spesia M.B.,National University of Rio Cuarto | Zorreguieta A.,University of Buenos Aires | Giordano W.,National University of Rio Cuarto
Applied and Environmental Microbiology | Year: 2012

Sinorhizobium meliloti is a symbiotic nitrogen-fixing bacterium that elicits nodule formation on roots of alfalfa plants. S. meliloti produces two exopolysaccharides (EPSs), termed EPS I and EPS II, that are both able to promote symbiosis. EPS I and EPS II are secreted in two major fractions that reflect differing degrees of subunit polymerization, designated high- and low-molecularweight fractions. We reported previously that EPSs are crucial for autoaggregation and biofilm formation in S. meliloti reference strains and isogenic mutants. However, the previous observations were obtained by use of "domesticated" laboratory strains, with mutations resulting from successive passages under unnatural conditions, as has been documented for reference strain Rm1021. In the present study, we analyzed the autoaggregation and biofilm formation abilities of native S. meliloti strains isolated from root nodules of alfalfa plants grown in four regions of Argentina. 16S rRNA gene analysis of all the native isolates revealed a high degree of identity with reference S. meliloti strains. PCR analysis of the expR gene of all the isolates showed that, as in the case of reference strain Rm8530, this gene is not interrupted by an insertion sequence (IS) element. A positive correlation was found between autoaggregation and biofilm formation abilities in these rhizobia, indicating that both processes depend on the same physical adhesive forces. Extracellular complementation experiments using mutants of the native strains showed that autoaggregation was dependent on EPS II production. Our results indicate that a functional EPS II synthetic pathway and its proper regulation are essential for cell-cell interactions and surface attachment of S. meliloti. © 2012, American Society for Microbiology.

Valentinuzzi M.E.,University of Buenos Aires
IEEE Pulse | Year: 2013

Discusses the lost art of handwritten letters, documentation, and correspondence and examines what we are missing from digital forms of communications such as emails and online texting. © 2010-2012 IEEE.

Holper L.,University of Zurich | Holper L.,ETH Zurich | Scholkmann F.,University of Zurich | Shalom D.E.,University of Buenos Aires | Wolf M.,University of Zurich
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.

Ramos V.A.,University of Buenos Aires
Journal of South American Earth Sciences | Year: 2010

The analysis of the basement of the Andes shows the strong Grenville affinities of most of the inliers exposed in the different terranes from Colombia to Patagonia. The terranes have different histories, but most of them participated in the Rodinia supercontinent amalgamation during the Mesoproterozoic between 1200 and 1000 Ma. After Rodinia break-up some terranes were left in the Laurentian side such as Cuyania and Chilenia, while others stayed in the Gondwanan side. Some of the terranes once collided with the Amazon craton remained attached, experiencing diverse rifting episodes all along the Phanerozoic, as the Arequipa and Pampia terranes. Some other basement inliers were detached in the Neoproterozoic and amalgamated again to Gondwana in the Early Cambrian, Middle Ordovician or Permian times. A few basement inliers with Permian metamorphic ages were transferred to Gondwana after Pangea break-up from the Laurentian side. Some of them were part of the present Middle America terrane. An exceptional case is the Oaxaquia terrane that was detached from the Gondwana margin after the Early Ordovician and is now one of the main Mexican terranes that collided with Laurentia. These displacements, detachments, and amalgamations indicate a complex terrane transfer between Laurentia and Gondwana during Paleozoic times, following plate reorganizations and changes in the absolute motion of Gondwana. © 2009 Elsevier Ltd. 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).

Cotik V.,University of Buenos Aires
IJCAI International Joint Conference on Artificial Intelligence | Year: 2015

Automatic detection of relevant terms in medical reports is useful for educational purposes and for clinical research. Natural language processing techniques can be applied in order to identify them. The main goal of this research is to develop a method to identify whether medical reports of imaging studies (usually called radiology reports) written in Spanish are important (in the sense that they have non-negated pathological findings) or not. We also try to identify which finding is present and if possible its relationship with anatomical entities.

Sourrouille L.,University of Buenos Aires
Modern Physics Letters A | Year: 2011

We show that the Chern-Simons-CP(1) model can support a singular soliton solution in which the magnetic field is a Dirac delta. © 2011 World Scientific Publishing Company.

Grinberg H.,University of Buenos Aires | Grinberg H.,CONICET
Annals of Physics | Year: 2011

An intensity dependent nonlinear coupling model of N two-level atoms (generalized Dicke model) interacting dispersively with a bimodal cavity field via two-photon transitions is investigated in a scenario where the rotating wave approximation is assumed. The model becomes homogeneous in the sense that the spin transition frequency is the same for all atoms and the coupling constants emerging from the collective interactions of the atomic system with the cavity field depend only on the particular radiation field mode. This allows us to represent the Dicke Hamiltonian entirely in terms of the total angular momentum J. It is assumed that, initially, the atomic system and the field are in a disentangled state where the field modes are in Glauber coherent states and the atomic system is a superposition of states |JM (Dicke states). The model is numerically tested against simulations of normal squeezing variance of the field, squeezing factors based on the Heisenberg uncertainty principle, along with the statistical properties of the light leading to the possible production of nonclassical effects, such as degree of second-order coherence in the modes, degree of intermode correlation, as well as violation of the Cauchy-Schwartz inequality. Analytical expression of the total density operator matrix elements at t>0 shows the present nonlinear model to be strongly entangled, which is reflected in the time evolution of the linear entropy, where the superposition states are reduced to statistical mixtures. Thus, the present generalized Dicke model does not preserve the modulus of the Bloch vector. The computations, performed in the weak coupling and strong field limits, were conducted via second-order Dyson perturbative expansion of the time evolution operator matrix elements for the totality of the angular momentum states of the atomic system. © 2011 Elsevier Inc.

Lasaga M.,University of Buenos Aires | Debeljuk L.,Southern Illinois University Carbondale
Peptides | Year: 2011

Tachykinins play a critical role in neuroendocrine regulation of reproduction. The best known members of the family are substance P (SP), neurokinin A and neurokinin B. Tachykinins mediate their biological actions through three G protein-coupled receptors, named NK1, NK2, and NK3. SP was suggested to play an important role in the ovulatory process in mammals and humans. Recent findings suggest a role of tachykinins in the aging of the hypothalamo-pituitary-gonadal axis. A high presence of SP was found in the sheep pars tuberalis and evidence indicates that it may have some role in the control of prolactin secretion. The presence of SP was confirmed in Leydig cells of the rat testes of animals submitted to constant light or treated with estrogens. Tachykinins were found to increase the motility of human spermatozoa. Tachykinins were also found to be present in the mouse ovary and more specifically, in the granulose cells. It is possible that tachykinins may play an important role in the ovarian function. NKB has been implicated in the steroid feedback control of GnRH release. Human mutations in the gene encoding this peptide or its receptor (TACR3) lead to a defect in the control of GnRH. A specific subset of neurons in the arcuate nucleus of the hypothalamus, colocalized three neuropeptides, kisspeptin, NKB and dynorphin. This subpopulation of neurons mediates the gonadal hormone feedback control of GnRH secretion. NKB/NK3 signaling plays a role in puberty onset and fertility in humans. This minireview summarizes the recent data about the action of tachykinins on the hypothalamo-pituitary-gonadal axis. © 2011 Elsevier Inc.

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.

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.

Gershanik O.,University of Buenos Aires | Jenner P.,Kings 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.

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.

Stortz C.A.,University of Buenos Aires
Journal of Physical Organic Chemistry | Year: 2010

The conformational equilibria of cyclohexane (as well as its fluoro-, chloro-, methyl-, hydroxy-, and t-butyl derivatives), cyclohexanone, piperidine, tetrahydropyran (and its 2-hydroxy derivative) were studied by ab initio and DFT procedures. The transition states were calculated at HF/6-31G, B3LYP/6-31+G*, and B3LYP/6-311+G* levels, whereas the intrinsic reaction coordinates (IRCs) were evaluated at the B3LYP/6-31+G* level. The degree of puckering and energy data was nearly not basis set-dependent (using B3LYP) in most of the cases. However, DFT methods gave better agreement with experimental data than HF methods, as expected from electron correlation inclusion. Fluorocyclohexane and 2-hydroxytetrahydropyran showed the largest basis set-energy dependence. It was found that the conversion from chair to skew is direct in some cases, whereas in others it goes through the pseudorotational (skew/boat) pathway. The case of t-butylcyclohexane, with a skew form as stable as one of the chairs, is especially interesting. In this compound, as well as in cyclohexanone and 2-hydroxytetrahydropyran, large deviations from the known pseudorotation/inversion scheme are observed. Copyright © 2010 John Wiley & Sons, Ltd.

Maldonado A.F.,CONICET | Melo J.I.,University of Buenos Aires | Aucar G.A.,CONICET
Physical Chemistry Chemical Physics | Year: 2015

Accurate calculations of nuclear magnetic shieldings of group-11 metal halides, σ(M; MX) (M = Cu, Ag, Au; X = H, F, Cl, Br, I), were performed with relativistic and nonrelativistic theoretical schemes in order to learn more about the importance of the involved electronic mechanisms that underlie such shieldings. We applied state of the art schemes: polarization propagators at a random phase level of approach (PP-RPA); spin-free Hamiltonian (SF); linear response elimination of small component (LRESC) and density functional theory (DFT) with two different functionals: B3LYP and PBE0. The results from DFT calculations are not close to those from the relativistic polarization propagator calculations at the RPA level of approach (RelPP-RPA), in line with previous results. The spin-orbit (SO) contribution to a shielding constant is important only for MF molecules (M = Cu, Ag, Au). Different electronic mechanisms are considered within the LRESC method, bunched into two groups: core- and ligand-dependent. For the analysed shieldings the core-dependent electronic mechanisms are the most important ones; the ligand-dependent being only important for MF molecules. An out of range value for σ(Au) is found in AuF. It was previously reported in the literature, either originated in the large fluorine electronegativity together with large spin-orbit coupling contributions; or, due to Fermi-contact contributions. We argue here that such an unexpected large value is an artifact originated in the appearance of quasi instabilities, and show how to handle this apparent problem. This journal is © the Owner Societies 2015.

Giordano M.,CONICET | Croci D.O.,CONICET | Rabinovich G.A.,CONICET | Rabinovich G.A.,University of Buenos Aires
Current Opinion in Hematology | Year: 2013

Purpose of Review: Galectins are a family of lectin molecules that have emerged as key players in inflammation and tumor progresssion by displaying intracellular and extracellular activities. This review describes the recent advances on the role of galectins in hematological neoplasms. RECENT FINDINGS: Galectin-1 and galectin-3 are the best studied galectins in oncohematology. Increased expression of galectin-1 has been associated with tumor progression in HodgkinÊs lymphoma and chronic lymphocytic leukemia, whereas galectin-3 plays a supporting role in chronic myelogenous leukemia and multiple myeloma. Functional studies have assigned a key role for galectin-1 as a negative regulator of T-cell immunity in HodgkinÊs lymphoma and cutaneous T-cell lymphoma. Of therapeutic interest is the development of agents with the capacity to interfere with galectin functions. SUMMARY: Current knowledge indicates a key role for galectins in hematological neoplasms by favoring the growth and survival of tumor cells and facilitating tumor immune escape. Intervention using specific galectin inhibitors is emerging as an attractive therapeutic option to alter the course of these malignancies. © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins.

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.

Bordoni N.,University of Buenos Aires
Acta odontológica latinoamericana : AOL | Year: 2012

Health is currently recognized as lying in the individual process rooted in genes, personal habits, the social model and the understanding of the ideological standpoint from which it is viewed. The aim of this study was to validate the Early Childhood Oral Health Impact Scale (ECOHIS) for use in Latin American communities, in order to demonstrate its efficacy for determining the impact of dental condition on children under 5 years of age and their families. The ECOHIS explores two domains: impact on children (9 questions) and on families (4 questions). Validation in Spanish was done in four stages. Stage I included translation and back-translation of the questionnaire (English-Spanish-English). Stage II was a pilot test on families in Venezuela to test stability (test-retest) and make semantic adjustments. Stage III included validation of the questionnaire applied to a Venezuelan sample (n = 50) and two Argentine samples (A and B, made up of families with and without social risk, respectively; n = 95), and consisted of statistical analysis to check the questionnaire's internal consistency and discriminant capacity. In the final stage, parents were given feedback on the results and significance of each domain in the questionnaire. From the results of this study it may be concluded that the Spanish version of the ECOHIS was reliable and valid for administering to populations with homogeneous social risk, and that parents without social risk factors (AC/B) have significantly greater perception of the impact of oral health on the family's quality of life. The trends recorded suggest that (a) larger samples should be used, including variables for diagnosing social vulnerability or general risk, (b) the association with dental condition should be established by applying indicators to discriminate distinct cut-off points in the dental caries process and (c) it should be ascertained whether there are changes in perception of the impact on quality of life before and after dental treatments, including impact on general health condition.

Zilli D.,PINMATE | Bonelli P.R.,PINMATE | Cukierman A.L.,PINMATE | Cukierman A.L.,University of Buenos Aires
Sensors and Actuators, B: Chemical | Year: 2011

Multi-walled carbon nanotubes (MWCNTs) are successfully processed in the form of thin films (buckypapers), and their morphology and electrical behaviour are characterized. The MWCNTs are synthesized by the floating catalyst chemical vapour deposition process. The effects of a sequence of treatments applied for MWCNTs purification on the buckypapers electrical behaviour are also examined. Nanocomposite thin films constituted of pristine and purified MWCNTs and Pd nanoparticles are prepared in order to evaluate their viability as H 2 sensors at room temperature. For this purpose, the electrical resistance of the nanocomposite films in atmospheres with different H 2 concentrations, is determined. Scanning electron microscopy (SEM) images show that the buckypapers and the nanocomposite films are 2D structures constituted by randomly oriented MWCNTs. The buckypapers present a semiconductor-like electrical behaviour as determined by the standard four point method. Room temperature resistivity values of around 10 -3 Ω m are assessed. Nanocomposite films show different electrical behaviour depending on the purification treatment applied to the MWCNTs employed. Furthermore, the electrical resistance of the nanocomposite films is found to increase when the measurements are performed in H 2 atmosphere. Values of H 2 sensitivity at room temperature of the nanocomposite films up to 2.15% are determined for H 2 average concentration higher than 350 ppm with short recovery time. © 2011 Elsevier B.V. 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.

Urrutia I.,University of Buenos Aires
Journal of Chemical Physics | Year: 2010

The partition function of two hard spheres in a hard-wall pore is studied, appealing to a graph representation. The exact evaluation of the canonical partition function and the one-body distribution function in three different shaped pores are achieved. The analyzed simple geometries are the cuboidal, cylindrical, and ellipsoidal cavities. Results have been compared with two previously studied geometries; the spherical pore and the spherical pore with a hard core. The search of common features in the analytic structure of the partition functions in terms of their length parameters and their volumes, surface area, edges length, and curvatures is addressed too. A general framework for the exact thermodynamic analysis of systems with few and many particles in terms of a set of thermodynamic measures is discussed. We found that an exact thermodynamic description is feasible based on the adoption of an adequate set of measures and the search of the free energy dependence on the adopted measure set. A relation similar to the Laplace equation for the fluid-vapor interface is obtained, which expresses the equilibrium between magnitudes that in extended systems are intensive variables. This exact description is applied to study the thermodynamic behavior of the two hard spheres in a hard-wall pore for the analyzed different geometries. We obtain analytically the external reversible work, the pressure on the wall, the pressure in the homogeneous region, the wall-fluid surface tension, the line tension, and other similar properties. © 2010 American Institute of Physics.

Marino C.,University of Buenos Aires
Chembiochem : a European journal of chemical biology | Year: 2014

D-Galactofuranose (D-Galf) is present in glycoconjugates of several pathogenic microorganisms but is absent in mammals, so it is a good target for the development of chemotherapeutic agents for the treatment of microbial infections. This fact has increased interest in the synthesis of D-Galf-containing molecules for corresponding glycobiological studies. The synthesis of oligosaccharides, glycoconjugates, and mimetics of D-Galf requires specific methods for the preparation of galactose derivatives in the furanosic configuration, the synthesis of appropriate acceptors, and efficient glycosylation methods for the construction of α- and β-D-Galf linkages. This review summarizes the different strategies developed for the preparation of partially protected derivatives of D-Galf, suitable as acceptors for the construction of (1→2), (1→3), (1→5), and (1→6) link- ages, and describes recent applications. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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.

Lavore A.,National University of La Plata | Pagola L.,National University of La Plata | Esponda-Behrens N.,National University of La Plata | Rivera-Pomar R.,National University of La Plata | Rivera-Pomar R.,University of Buenos Aires
Developmental Biology | Year: 2012

The segmentation process in insects depends on a hierarchical cascade of gene activity. The first effectors downstream of the maternal activation are the gap genes, which divide the embryo in broad fields. We discovered a sequence corresponding to the leucine-zipper domain of the orthologue of the gene giant (Rp- gt) in traces from the genome of Rhodnius prolixus, a hemipteran with intermediate germ-band development. We cloned the Rp- gt gene from a normalized cDNA library and characterized its expression and function. Bioinformatic analysis of 12.5. kbp of genomic sequence containing the Rp- gt transcriptional unit shows a cluster of bona fide regulatory binding sites, which is similar in location and structure to the predicted posterior expression domain of the Drosophila orthologue. Rp-gt is expressed in ovaries and maternally supplied in the early embryo. The maternal contribution forms a gradient of scattered patches of mRNA in the preblastoderm embryo. Zygotic Rp-gt is expressed in two domains that after germ band extension are restricted to the head and the posterior growth zone. Parental RNAi shows that Rp-gt is required for proper head and abdomen formation. The head lacks mandibulary and maxillary appendages and shows reduced clypeus-labrum, while the abdomen lacks anterior segments. We conclude that Rp-gt is a gap gene on the head and abdomen and, in addition, has a function in patterning the anterior head capsule suggesting that the function of gt in hemipterans is more similar to dipterans than expected. © 2011.

Bengochea G.R.,CONICET | De Rossi M.E.,CONICET | De Rossi M.E.,University of Buenos Aires
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2014

In this work, we show that when supernova Ia (SN Ia) data sets are used to put constraints on the free parameters of inhomogeneous models, certain extra information regarding the light-curve fitter used in the supernovae Ia luminosity fluxes processing should be taken into account. We found that the size of the void as well as other parameters of these models might be suffering extra degenerations or additional systematic errors due to the fitter. A recent proposal to relieve the tension between the results from Planck satellite and SNe Ia is re-analyzed in the framework of these subjects. © 2014 The Authors.

Frankel N.,University of Buenos Aires
Developmental Dynamics | Year: 2012

Genomes contain the necessary information to ensure that genes are expressed in the right place, at the right time, and with the proper rate. Metazoan developmental genes often possess long stretches of DNA flanking their coding sequences and/or large introns which contain elements that influence gene expression. Most of these regulatory elements are relatively small and can be studied in isolation. For example, transcriptional enhancers, the elements that generate the expression pattern of a gene, have been traditionally studied with reporter constructs in transgenic animals. These studies have provided and will provide invaluable insights into enhancer evolution and function. However, this experimental approach has its limits; often, enhancer elements do not faithfully recapitulate native expression patterns. This fact suggests that additional information in cis-regulatory regions modulates the activity of enhancers and other regulatory elements. Indeed, recent studies have revealed novel functional aspects at the level of whole cis-regulatory regions. First, the discovery of "shadow enhancers." Second, the ubiquitous interactions between cis-regulatory elements. Third, the notion that some cis-regulatory regions may not function in a modular manner. Last, the effect of chromatin conformation on cis-regulatory activity. In this article, I describe these recent findings and discuss open questions in the field. © 2012 Wiley Periodicals, Inc.

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

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

Wolansky M.J.,University of Buenos Aires | Tornero-Velez R.,U.S. Environmental Protection Agency
Journal of Toxicology and Environmental Health - Part B: Critical Reviews | Year: 2013

Pyrethroids (PYR) are pesticides with high insecticidal activity that may disrupt neuronal excitability in target and nontarget species. The accumulated evidence consistently showed that this neurophysiologic action is followed by alterations in motor, sensorimotor, neuromuscular, and thermoregulatory responses. Nevertheless, there are some equivocal results regarding the potency of PYR in lab animals. The estimation of potency is an important step in pesticide chemical risk assessment. In order to identify the variables influencing neurobehavioral findings across PYR studies, evidence on experimental and organismic determinants of acute PYR-induced neurotoxicity was reviewed in rodents. A comprehensive analysis of these studies was conducted focusing on test material and dosing conditions, testing conditions, animal models, and other determinants such as testing room temperature. Variations in the severity of the neurotoxicity, under lab-controlled conditions, was explained based upon factors including influence of animal species and age, test material features such as chemical structure and stereochemistry, and dosing conditions such as vehicle, route of exposure, and dose volume. If not controlled, the interplay of these factors may lead to large variance in potency estimation. This review examined the scope of acute toxicological data required to determine the safety of pesticide products, and factors and covariates that need to be controlled in order to ensure that predictivity and precaution are balanced in a risk assessment process within a reasonable time-frame, using acute PYR-induced neurotoxicity in rodents as an exemplar. Copyright © 2013 Taylor and Francis Group, LLC.

Feldstein C.A.,University of Buenos Aires
Journal of Alzheimer's Disease | Year: 2012

Epidemiological studies suggest an association between chronic blood pressure (BP) changes and Alzheimer's disease (AD). In particular, there is growing evidence that hypertensive people that do not have their BP adequately treated and controlled in midlife are more likely to develop AD in late-life. It has been hypothesized that cerebrovascular disease is a common pathway which connects hypertension and AD in individuals with apolipoprotein E genotype through brain hypoperfusion and hypoxia. This could accelerate amyloid-β aggregation that disrupts cell-to-cell connectivity and leads to eventual brain neuron loss. Also, high BP contributes to worsen AD by raising oxidative stress and inflammatory response. Aging-related structural and functional disturbances appear to exacerbate the deleterious effect of chronic hypertension on cerebral blood flow autoregulation. There is evidence suggesting that some antihypertensive drug classes reduce the risk and progression of AD more than others. Further prospective randomized studies comparing different classes of antihypertensive drugs are needed to provide more evidence regarding their effects on AD risk. Hypotension could be a consequence of the incident dementia and conversely deteriorate the outcome of AD by worsening brain hypoperfusion. Frequent home BP monitoring should be carried out in AD patients to detect harmful orthostatic hypotension. © 2012 - IOS Press and the authors. All rights reserved.

Niederman M.S.,Winthrop University | Niederman M.S.,State University of New York at Stony Brook | Luna C.M.,Hospital de 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.

This paper explores food and daily activities in domestic areas at the archaeological site of Cardonal, Provincia de Catamarca, Argentina. It is based on archaeobotanical carpological macro remains recovered by flotation techniques in a residential compound. A set of five taxa including wild plants such as Geoffroea decorticans (chañar), Phaseolus vulgaris var. aborigineus (wild bean), Prosopis sp. (algarrobo) and the crops P. vulgaris var. vulgaris (domesticated bean) and Zea mays (maize) were identified. These well-known staples of ancient communities in this area suggest that the Cardonal people combined agriculture with foraging practices, taking advantage of a diversified environment and extensive social networks. The most abundant plant food remains were bean cotyledons and maize cupules, which were densely concentrated in the "kitchen", near the hearth. Conversely, chañar endocarps, algarrobo seeds and also Chenopodium sp. seeds were almost exclusively confined to the "patio", in the hearth area. As a result, two distinct food-related activity areas could be identified, defined by the relative density of plant remains, occurrence of plant taxa and the different practices of processing and consumption which they evoke. © 2013 Springer-Verlag Berlin Heidelberg.

Montoya S.,University of Caldas | Orrego C.E.,National University of Colombia | Levin L.,University of Buenos Aires
World Journal of Microbiology and Biotechnology | Year: 2012

Cultivation of specialty mushrooms on lignocellulosic wastes represents one of the most economical organic recycling processes. Compared with other cultivated mushrooms, very little is known about the nature of the lignocellulolytic enzymes produced by the edible and medicinal fungus Grifola frondosa, the parameters affecting their production, and enzyme activity profiles during different stages of the developmental cycle. In this work we investigated the enzymes that enable G. frondosa, to colonize and deconstruct two formulations based on industrial lignocellulosic by-products. G. frondosa degraded both substrates (oak-sawdust plus corn bran, and oak/corn bran supplemented with coffee spent-ground) decreasing 67 and 50% of their lignin content, along with 44 and 37% of the polysaccharides (hemicellulose and cellulose) respectively. 35.3% biological efficiency was obtained when using oak sawdust plus corn bran as substrate. Coffee spent-ground addition inhibited mushroom production, decreased growth, xylanase and cellulase activities. However, taking into account that G. frondosa successfully colonized this residue; this substrate formula might be considered for its growth and medicinal polysaccharide production. Although G. frondosa tested positive for Azure B plate degradation, a qualitative assay for lignin-peroxidase, attempts to detect this activity during solid state fermentation were unsuccessful. Enzyme activities peaked during colonization but declined drastically during fruiting body formation. Highest activities achieved were: endoglucanase 12.3, exoglucanase 16.2, β-glucosidase 2.3, endoxylanase 20.3, amylase 0.26, laccase 14.8 and Mn-peroxidase 7.4 U/g dry substrate. © 2011 Springer Science+Business Media B.V.

Hoppe A.,Friedrich - Alexander - University, Erlangen - Nuremberg | Mourino V.,University of Buenos Aires | Mourino V.,CONICET | Boccaccini A.R.,Friedrich - Alexander - University, Erlangen - Nuremberg
Biomaterials Science | Year: 2013

Bioactive glasses (BG) are being widely used for bone tissue engineering applications due to their bioactivity (ability to form strong bonds to bone) and their stimulating effects on bone formation. Recently, progress has been made to enhance the biological impact of BGs by incorporating specific metallic ions in silicate (or phosphate) glasses, including boron, copper, cobalt, silver, zinc and strontium. This review summarizes the newest developments on novel compositions of bioactive glasses in the field of bone tissue engineering related to osteogenesis and angiogenesis. Furthermore, new applications areas for bioactive glasses, including nerve regeneration and cancer treatment, are highlighted. © 2013 The Royal Society of Chemistry.

Giribet G.,Solvay Group | Giribet G.,University of Buenos Aires | Giribet G.,Pontifical Catholic University of Valparaiso
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.

Cherbiy-Hoffmann S.U.,CONICET | Hall A.J.,University of Buenos Aires | Rousseaux M.C.,CONICET
Scientia Horticulturae | Year: 2013

Maximizing productivity in super high density and intensive olive orchards requires proper management of illumination of the canopy walls and their interior. Currently, this is difficult to achieve due to the limited knowledge about the responses to incident photosynthetically active radiation (PAR) of yield determinants and components. We determined the response functions for PAR during the oil synthesis phase of yield components (fruit dry weight and oil concentration) of fruit at a height of 2m on the canopy periphery by applying several radiation levels (3, 20, 40, and 70% of incident PAR) to the north side (S hemisphere) of well-illuminated trees. The experiment was initiated after endocarp hardening as fruit number had already been established at that time. This avoided possible confounding effects due compensation between fruit number and size. Absence of differential fruit fall in response to treatments and of changes in (endocarp+seed) dry weight after application of treatment confirmed the achievement of this objective. Fruit dry weight, oil concentration, and, consequently, yield increased linearly with mean daily PAR receipt up to a threshold of 15mol PARm-2d-1 (i.e., 40% of PAR). In treatments with irradiance levels below this threshold the fruit became the priority sinks for assimilates, although their growth rate and oil concentration were reduced. Increments in length of non-fruiting branches and of trunk cross-sectional areas were substantially reduced in response to shading. We conclude that manipulation of PAR levels during the oil synthesis phase can reduce final fruit dry weight and oil concentration, confirms the existence of upper thresholds to PAR responses for these variables, and provides evidence that fruit growth has priority in the partitioning of photosynthate over vegetative growth under low to moderate levels of PAR. © 2012 Elsevier B.V.

Hall A.J.,University of Buenos Aires | Richards R.A.,CSIRO
Field Crops Research | Year: 2013

Genetic improvement of crop yields under potential (Yp) and water scarce conditions (Yw) will be an important avenue to improved food security over the next four decades, at the end of which projected demand for food, feed and biofuel feedstock is expected to level out. Current measured relative rates of improvement in Yp and Yw for the three main cereal crops (maize, wheat and rice) in many cropping systems in the world are mostly well below the 1.16-1.31%y-1 rates required to meet projected demand for cereals in 2050. These relative rates can be expected to fall further if the current absolute rates of yield improvement continue unchanged and/or the current indications of stagnation in yield improvement for some crops in some regions of the world become widespread. This review assesses the available evidence for unexploited opportunities for enhancing current rates of genetic improvement for Yp and Yw, and examines some substantive proposals for achieving the same end through genetic engineering of photosynthesis, above-ground ideotype design, and improvement of root capacity for water uptake. Because time is of the essence, special attention is paid to the time scales required to progress potentially useful traits through to proof of concept under field conditions, from there to farmer-ready cultivars, and for widespread adoption by farmers of the improved cultivars. The requirements of breeders for inclusion of potentially important traits into the conventional breeding process are outlined and the value of molecular breeding tools as aids to genetic improvement of simple and complex traits is considered. Intellectual property and regulatory requirements are taken as additional potential drags on the rates of adoption into the breeding process of useful traits and/or to the free flow of information between research teams. Main conclusions are: (a) there are some unexploited opportunities to improve Yp or Yw in some crops and/or cropping systems; (b) exploitation of these opportunities could be hastened by increasing funding for focussed research and by identifying and eliminating or reducing drags at various stages of the idea to farmer-ready cultivar chain; (c) the time-scales required for major improvements in yield in farmer-ready cultivars through genetic engineering or ideotype realisation are likely to be measured in decades rather than years; (d) current and expected future relative rates of progress in Yp and Yw are a matter of real concern and are insufficient to meet projected demand for cereals by 2050. Possible step changes in Yp or Yw powered by genetic improvements such as exploitation of hybrid vigour in rice or hypothetical successes in the genetic engineering of photosynthesis are unlikely to change this outlook. The pessimistic assessments embodied in the last two conclusions should not obscure the fact that without continued investment in the search for sources of genetic improvement and development of aids to breeding, the unmet demands for cereals in 2050 will be even greater. © 2012 Elsevier B.V.

Cardona C.A.,CONICET | Cardona C.A.,University of Buenos Aires
Nuclear Physics B | Year: 2013

We discuss the relation between correlation functions of twist-two large spin operators and expectation values of Wilson loops along light-like trajectories. After presenting some heuristic field theoretical arguments suggesting this relation, we compute the divergent part of the correlator in the limit of large 't Hooft coupling and large spins, using a semi-classical world-sheet which asymptotically looks like a GKP rotating string. We show this diverges as expected from the expectation value of a null Wilson loop, namely, as (lnμ-2)2, μ being a cut-off of the theory. © 2012 Elsevier B.V.

Ramirez C.,Autonomous University of Barcelona | Lizana A.,Autonomous University of Barcelona | Iemmi C.,University of Buenos Aires | Campos J.,Autonomous University of Barcelona
Optics Letters | Year: 2015

This Letter proposes a new optical architecture based on a double-sideband filter, simultaneously applied at the Fourier plane, for inline digital holography. The proposed architecture not only allows removal of the conjugate images in the reconstruction process but also reduces the distortions that usually appear when using a single-sideband filter. We first introduce the mathematical model that explains the method and then describe the optical setup used for the implementation. The optical system includes a parallel aligned liquid crystal display placed at the Fourier plane that simultaneously filters positive and negative frequencies, when properly combined with linear polarizers. This feature makes the device useful to register dynamic processes. Finally, we tested the setup by registering a holographic movie of microscopic moving objects placed at different planes. © 2015 Optical Society of America.

Ruiz-Moreno D.,University of Buenos Aires
BMC Infectious Diseases | Year: 2016

Background: Chikungunya fever is a viral disease that recently invaded the American continent. In America, it is transmitted mainly by the mosquito Aedes aegypti, but Aedes albopictus is the main vector in other regions of the world. This work estimates the risk of disease emergence and the corresponding population at risk for the case of a naive population in the metropolitan area of Buenos Aires, the capital city of Argentina. Methods: A classic metapopulation epidemiological model, that considers human and mosquito populations, was extended in order to include different environmental signals. First, the vital rates of the mosquitoes were affected by local temperature. Second, habitat availability estimated from satellite images was used to determine the carrying capacity for local mosquito populations. Disease invasion was proposed to occur at different moments of the year. For each scenario, Monte Carlo simulations were used to estimate the risk of disease invasion and the population at risk. Results: The risk of a Chikungunya outbreak displays strong temporal (seasonal) patterns as well as spatial variability at the level of neighborhoods in the study area. According to the model, Summer and Fall display high risk for a Chikungunya invasion. The population at risk displays less variation over the year underlying the importance of preventive actions. Conclusions: The ability of mapping habitat quality for vector-borne diseases allows developing risk analysis at scales that are easily manageable for public health officers. For this location, the correlation of disease risk with the season of the year and the habitat availability could provide information to develop efficient control strategies. This also underlines the importance of involving the whole community when developing control measures for Chikungunya fever and other recently invading vector-borne diseases such as Zika fever. © 2016 Ruiz-Moreno.

Berini C.A.,University of Buenos Aires
AIDS research and human retroviruses | Year: 2012

Human T-lymphotropic virus subtype b (HTLV-2b) infection has been described among aborigines from Northern Argentina, while HTLV-2a has been described in an injecting drug user (IDU) from a Central region, similar to the situation in Spain, the United States, and Brazil. In this study, 22 of the 26 strains analyzed from blood donors and HIV-1(+) individuals were HTLV-2b (84.6%) clustering with Amerindian references, while 4 HIV-1(+) (15.4%) were HTLV-2a. HTLV-2a sequences were closely related to Brazilian references in contrast to the previous Argentinean IDU strain that clustered with Africans and Amerindians from North America. In summary, these findings show that HTLV-2b is the major strain circulating in an urban population of Argentina. HTLV-2a/b could have been introduced from endemic South American countries such as Brazil and because of contact with other populations such as IDUs from Europe despite its introduction due to the increasing internal migration of aborigines to large urban centers. Considering this results and recent data about the dissemination of HTLV-1 in residents of Buenos Aires city, new studies among non-at-risk groups for HTLV-1/2 infection should be performed.

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.

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.

Garcia-Mata I.,CONICET | Pineda C.,National Autonomous University of Mexico | Wisniacki D.,University of Buenos Aires
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2012

We study the influence of a chaotic environment in the evolution of an open quantum system. We show that there is an inverse relation between chaos and non-Markovianity. In particular, we remark on the deep relation of the short time non-Markovian behavior with the revivals of the average fidelity amplitude-a fundamental quantity used to measure sensitivity to perturbations and to identify quantum chaos. The long time behavior is established as a finite size effect which vanishes for large enough environments. © 2012 American Physical Society.

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.

Gambin B.L.,National University of Rosario | Gambin B.L.,University of Buenos Aires | Borras L.,National University of Rosario
Annals of Applied Biology | Year: 2010

In grain crops, total sink capacity is usually analysed in terms of two components, seed number and individual seed weight. Seed number and potential individual seed weight are established at a similar timing, around the flowering period, and seed weight at maturity is highly correlated with the potential established earlier. It is known that, within a species, available resources during the seed set period are distributed between both yield components, resulting in a trade-off between seed number and seed weight. Here we tested if this concept could apply for interspecific comparisons, where combinations of numbers and size across species could be related to the total available resources being either allocated to more seed or larger potential individual seed weight during the seed set period. Based on this, species differences in seed weight should be related to resource availability per seed around the period when seed number is determined. Resource availability per seed was estimated as the rate of increase in aboveground biomass per seed around the period of seed set. Data from 15 crop species differing in plant growth, seed number, seed weight and seed composition were analysed from available literature. Because species differed in seed composition, seed weight was analysed following an energy requirement approach. There was an interspecific trade-off relationship between seed number per unit of land area and seed weight (r = 0.92; F(1, 13) = 32.9; n = 15; P < 0.001). Seed weight of different species was positively correlated (r = 0.90; F(1, 13) = 52.9; n = 15; P < 0.001) with resource availability per seed around the seed set period. This correlation included contrasting species like quinoa (Chenopodium quinoa; ∼100000 seeds m-2, ∼4 mg equivalent-glucose seed -1) or peanut (Arachis hypogaea; ∼800 seeds m-2, ∼1000 mg equivalent-glucose seed-1). Seed number and individual seed weight combinations across species were related and could be explained considering resource availability when plants are adjusting their seed number to the growth environment and seeds are establishing their storage capacity. Available resources around the seed set period are proportionally allocated to produce either many small seeds or few larger seeds depending on the particular species. © 2009 Association of Applied Biologists.

Hirschler V.,University of Buenos Aires
International Journal of Clinical Practice | Year: 2016

Background It is generally accepted that metabolic changes that take place in individuals exposed to high elevation are because of ambient hypoxia, which occurs as a consequence of a low total atmospheric pressure. The discovery of hypoxia inducible factor 1 (HIF1), a transcription factor, has been a breakthrough in the understanding of adaption to high altitudes. Objective The purpose of the present review was to discuss specific epidemiological aspects of cardiovascular disease (CVD) risk factors and their mechanisms in vulnerable, understudied populations living at high altitudes. Results Obesity prevalence has been inversely associated with elevation. HIF1 has been related to plasma leptin - a hormone secreted by adipose tissue that produces negative feedback on appetite - and inversely associated with obesity. Diverse factors, such as genetics, chronic hypoxia, diet and lifestyle behaviours, could have an influence on the high dyslipidaemia rates of high-altitude natives. Hypoxia could mediate the effects of altitude on human physiology, including lipid metabolism. Genetic studies suggest that dyslipidaemia could be related to the HIF1. Hypoxia inhibits oxidative phosphorylation and stimulates the oxygen signalling pathway through the HIF1. Low fasting glycaemia in individuals at high altitudes has been shown. An increased GLUT4 protein content in skeletal muscle in response to hypoxia has been reported and could be associated with lower glucose levels. Given the high prevalence of dyslipidaemia and the low prevalence of obesity and diabetes in these impoverished high-altitude communities, changes in lifestyle including decreased physical activity and the consumption of a more westernised diet would likely increase the prevalence of CVD related mortality. Conclusions Control over major CVD risk factors, when identified early, could be the key to reducing morbidity and mortality in patients with limited access to medical services such as Native populations. © 2015 John Wiley & Sons Ltd.

Kaski D.,Imperial College London | Dominguez R.O.,University of Buenos Aires | Allum J.H.,University of Basel | Bronstein A.M.,Imperial College London
Neurorehabilitation and Neural Repair | Year: 2013

Background. Leukoaraiosis describes ischemic white matter lesions, a leading cause of gait disturbance in the elderly. Objective. Our aim was to improve gait and balance in patients with leukoaraiosis by combining a single session of transcranial direct current stimulation (tDCS) and physical training (PT). Methods. We delivered anodal tDCS over midline motor and premotor areas in 9 patients with leukoaraiosis. Patients underwent gait and balance training during tDCS stimulation (real/sham). This was repeated 1 week later with the stimulation crossed-over (sham/real) in a double-blind design. Assessments included gait velocity, stride length, stride length variability (primary gait outcomes), and a quantitative retropulsion test (primary balance outcome). Results. Combining tDCS and PT improved gait velocity, stride length, stride length variability, and balance (all at P ≤.05). Overall, training without tDCS showed no significant effects. Conclusions. Combined anodal tDCS and PT improves gait and balance in this patient group, suggesting that tDCS could be an effective adjunct to PT in patients with leukoaraiosis, for whom no treatment is currently available. © The Author(s) 2013.

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.

Aguirre-Urreta B.,University of Buenos Aires | Rawson P.F.,University of Hull | Rawson P.F.,University College London
Cretaceous Research | Year: 2012

Although the Agrio Formation (Valanginian-Early Barremian) yields rich ammonite faunas at many levels, the highest beds are very sparsely fossiliferous. However, intensive collecting over the years has yielded a sparse fauna of heteromorph ammonites that are completely new to Argentina. Three taxa are represented, Sabaudiella riverorum sp. nov., Curacoites rotundus gen. et sp. nov. and Hamulinites? sp. The fauna is placed in a new ammonite zone of Sabaudiella riverorum and dated as latest Hauterivian-Early Barremian. © 2012 Elsevier Ltd.

Rubio M.C.,University of Buenos Aires
Acta odontológica latinoamericana : AOL | Year: 2013

There is evidence that acute myocardial infarction (AMI) is associated with increasing production of reactive oxygen species and tissue injury. The aim of this study was to assess the presence of oxidative stress indices in saliva 24 and 48h after AMI. We designed a prospective study comparing salivary levels of biomarkers of oxidative stress in patients with AMI with elevation of the ST segment in electrocardiogram versus clinically healthy subjects. Oxidative stress indices including the rate of oxidation of 2'7' dichlorohydrofluorescein diacetate (DCFH-DA) and the activity of the antioxidant enzyme catalase (CAT) were evaluated in saliva from patients with AMI at 24 and 48 hours. At each sampling time, blood was drawn for serum markers of myocardial infarction. This study included ten patients with acute ST-segment elevation myocardial infarction and ten clinically healthy controls. Mean age was 67.8 +/- 11.1 vs. 48.7 +/- 4.1 years (p < 0.001) and gender was 60% male vs. 50% (p > 0.05) for AMI vs. controls, respectively. Our results demonstrated an increase in the rate of oxidation of DCFH-DA in the myocardial infarction group as compared with controls (p = 0.004), which remained unchanged at 48h. There was no difference in salivary catalase activity between controls and AML subjects at 24h or at 48h post-diagnosis (p = 0.157). The relationship between CAT48 and DCFH-DA48 was fairly significant (r = 0.39; p = 0.053). This preliminary study showed that biomarkers of oxidative stress are detectable in saliva of patients with acute myocardial infarction. Future studies using a larger population are needed to confirm t