La evolución intelectual de la noción de materia en San Agustín de Hipona

El presente artículo estudia y analiza tanto el significado como la trayectoria intelectual de la noción de materia en el pensamiento de San Agustín, la cual, hallándose en un principio estrechamente unida a su interpretación del Génesis, termina por rebasar el ámbito estrictamente teológico para constituirse en una de las nociones claves para la comprensión de la metafísica agustiniana de la creación ex nihilo.The current article studies and analyzes both, the meaning and the matter-notion intellectual trajectory into St. Augustine’s thought, which –closely bound to the Genesis interpretation at the beginning- get to surpass the strictly theological scope to become a key notion to the comprehension of the augustinian metaphysics of the creation ex nihilo.Fil: Benavides G., Verónica. Universidad Adolfo Ibáñez (Santiago, Chile). Departamento de Filosofí

New Teaching Strategies to Improve Student Performance in Fundamentals of Biotechnology

<p>Fundamentals in Biotechnology is part of the Chemical Engineering curriculum at the National University at Salta, in northwest Argentina. This course, given for four months in the fourth year of a five-year program of study, includes concepts of general microbiology, biochemistry, and industrial microbiology and is the first contact by the students with biological issues. Probably due to the long content of the course and to the lack of previous knowledge of biological and microbiological concepts, students have a lot of difficulty passing this course. In order to reach a better understanding of the concepts, to encourage students to learn biotechnology, and to develop critical thinking skills with the ultimate aim of improving performance, two new strategies were adopted, which consisted of including “Complementary Activities” and an “Integration Seminar.”</p

Migração e Autonomia: os trabalhadores da floresta no nordeste de Misiones (Argentina)

Este artículo versa sobre los peones forestales de la provincia de Misiones (nordeste de Argentina), que se desplazan hacia los bosques cultivados de Eucaliptos, situados en las provincias de Corrientes y Entre Ríos. Analizamos este circuito de migración cíclica en términos de segmentación del mercado de trabajo. La condición social de los migrantes se define por la alternancia entre la venta de fuerza de trabajo y el trabajo para sí en la parcela. La búsqueda de autonomía constituye un valor central en la selección de alternativas laborales. Desde la perspectiva de la antropología, describimos las formas de organización social (fases del ciclo doméstico, redes sociales) y las categorías culturales que intervienen en la segmentación.The present article deals with the forestall workers of Misiones (northeast Argentina) that move towards the planted forests of Eucalyptuses, located in the provinces of Corrientes and Entre Ríos. The alternation between selling labour force and working for themselves in our land defines the migrant’s social condition.We analyse this cyclic migration circuit in terms of labour market segmentation. The search of autonomy represents a central value for labour selection alternatives. From the anthropological point of view we describes the social organization forms (domestic cycle phase, social networks) and cultural conceptions that underlying segmentation.O artigo trata dos trabalhadores florestais do nordeste de Misiones (Arg.) que se deslocam para os reflorestamentos de eucaliptos, localizados em lãs províncias de Entre Rios e Corrientes. Descrevemos o circuito de migração cíclica em termos de segmentação do mercado de trabalho. A condição social dos migrantes e definida considerando a alternância da venta de forca de trabalho e a produção própria. A busca da autonomia representa um valor significativo na seleção de alternativas de trabalho. Do ponto de vista da antropologia, o artigo descreve as formas sociais (ciclo domestico, redes) y os significados culturais que permeiam a segmentação do mercado.Fil: Schiavoni, Otilia Margarita G.. Universidad Nacional de Misiones; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Albertí, Alfonsina Verónica. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Saavedra 15. Centro de Estudios e Investigaciones Laborales; Argentin

Role of serotonergic neurons in the Drosophila larval response to light

<p>Abstract</p> <p>Background</p> <p><it>Drosophila </it>larval locomotion consists of forward peristalsis interrupted by episodes of pausing, turning and exploratory behavior (head swinging). This behavior can be regulated by visual input as seen by light-induced increase in pausing, head swinging and direction change as well as reduction of linear speed that characterizes the larval photophobic response. During 3^rdinstar stage, <it>Drosophila </it>larvae gradually cease to be repelled by light and are photoneutral by the time they wander in search for a place to undergo metamorphosis. Thus, <it>Drosophila </it>larval photobehavior can be used to study control of locomotion.</p> <p>Results</p> <p>We used targeted neuronal silencing to assess the role of candidate neurons in the regulation of larval photobehavior. Inactivation of DOPA decarboxylase (Ddc) neurons increases the response to light throughout larval development, including during the later stages of the 3^rdinstar characterized by photoneutral response. Increased response to light is characterized by increase in light-induced direction change and associated pause, and reduction of linear movement. Amongst Ddc neurons, suppression of the activity of corazonergic and serotonergic but not dopaminergic neurons increases the photophobic response observed during 3^rdinstar stage. Silencing of serotonergic neurons does not disrupt larval locomotion or the response to mechanical stimuli. Reduced serotonin (5-hydroxytryptamine, 5-HT) signaling within serotonergic neurons recapitulates the results obtained with targeted neuronal silencing. Ablation of serotonergic cells in the ventral nerve cord (VNC) does not affect the larval response to light. Similarly, disruption of serotonergic projections that contact the photoreceptor termini in the brain hemispheres does not impact the larval response to light. Finally, pan-neural over-expression of 5-HT1A_Droreceptors, but not of any other 5-HT receptor subtype, causes a significant decrease in the response to light of 3^rdinstar larvae.</p> <p>Conclusion</p> <p>Our data demonstrate that activity of serotonergic and corazonergic neurons contribute to the control of larval locomotion by light. We conclude that this control is carried out by 5-HT neurons located in the brain hemispheres, but does not appear to occur at the photoreceptor level and may be mediated by 5-HT1A_Droreceptors. These findings provide new insights into the function of 5-HT neurons in <it>Drosophila </it>larval behavior as well as into the mechanisms underlying regulation of larval response to light.</p

Different functional sensitivity to mutation at intersubunit interfaces involved in consecutive stages of foot-and-mouth disease virus assembly

© 2015 The Authors. Small spherical viruses are paradigms of supramolecular self-assembly. Identifying the specific structural determinants for virus assembly provides guidelines to develop new antiviral drugs or engineer modified viral particles for medical or technological applications. However, very few systematic studies have been carried out so far to identify those chemical groups at interfaces between virus capsid subunits that are important for viral assembly and function. Foot-and-mouth disease virus (FMDV) and other picornaviruses are assembled in a stepwise process in which different protein–protein interfaces are formed: 5 protomeric subunits oligomerize to form a pentameric intermediate, and 12 of these stable pentameric building blocks associate to form a labile capsid. In this study, a systematic mutational analysis revealed that very few amino acid side chains involved in substantial interactions between protomers within each pentamer are individually required for virus infectivity. This result contrasts sharply with the previous finding that most amino acid side chains involved in interactions between pentamers during the next assembly step are individually required for infectivity. The dramatic difference in sensitivity to single mutations between the two types of protein–protein interfaces in FMDV is discussed in terms of possible structural strategies for achieving self-assembly and genome uncoating in the face of diverse selective constraints.This work was funded by grants from the Spanish Government (BIO2009-10092 and BIO2012-37649) and Comunidad de Madrid (S-505/MAT-0303) to M. G. M., and by an institutional grant from Fundación Ramón Areces to the Centro de Biología Molecular ‘Severo Ochoa>Peer Reviewe

Kinetic Monte Carlo simulation of molecular processes on supported metal particles

A general model is proposed to describe the kinetics of molecular reactions taking place on supported metal particles, which are deformed by the effect of temperature, through kinetic Monte Carlo simulations. The model is applied to the study of the CO oxidation reaction. The effects of adsorbate-adsorbate and adsorbate-metal interactions and of CO and metal atoms diffusion on the reaction window and the overall reaction rate are determined.Fil: Sales, Jose Luis. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Física Aplicada "Dr. Jorge Andrés Zgrablich". Universidad Nacional de San Luis. Facultad de Ciencias Físico Matemáticas y Naturales. Instituto de Física Aplicada "Dr. Jorge Andrés Zgrablich"; ArgentinaFil: Gargiulo Almeida, María Verónica. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Física Aplicada "Dr. Jorge Andrés Zgrablich". Universidad Nacional de San Luis. Facultad de Ciencias Físico Matemáticas y Naturales. Instituto de Física Aplicada "Dr. Jorge Andrés Zgrablich"; ArgentinaFil: Zgrablich, G.. Universidad Nacional de San Luis; Argentin

RALF/LRX monitor cell wall integrity during tomato fruit formation

Plant developmental processes depend largely on a correct communication between cells, together with the ability to respond to such communication. Traditionally cell to cell communication has been studied through the action of phytohormones such as auxin, ethylene, etc. However, in the past decade, Small Signaling Peptides (SSPs) have been identified as key regulators coordinating an extensive range of developmental and stress processes. Plant cells perceive SSPs at the cell wall by Receptor-Like Kinases (RLKs), activating a huge range of biochemical and physiological processes. SSPs from Rapid Alkalinization Factor (RALFs) family are ubiquitous in dicot plants and they have been associated to cell wall integrity during cell wall remodeling. RALFs peptides can bind two types of receptors: Leucine-Rich Repeat Extensin proteins (LRXs), and Catharanthus roseus RLK1-Like (CrRLK1L). All recent discoveries remark the importance of RALF/LRX/CrRLK1L module regulating cell wall status. A tomato fruit formation is a perfect model to further understand the role of this mechanism, since requires a tightly regulation during the cell wall softening phase. It has already been reported that some members of CrRLK1Ls regulate fruit ripening in few species like tomato, strawberry or apple, remarking the importance of these receptors and their ligands sensing changes produced in the cell wall during the ripening process. Here, we initiate a biochemical and phenotypical characterization of RALF/LRX proteins in order to elucidate their role during tomato ripening process

Quantitative analysis of complex nanocomposites based on straight skeletonization

Bones are complex nanocomposites composed mainly by hydroxyapatite nanocrystals. Different factors characterize its morphology: composition, length, orientation, roughness. To increase our understanding of the tissue morphology at this fundamental lever of organization, a new method based on the straight skelonization of the images obtained by electronic microscopy is proposed. The method detects and measures the length and angularity of any straight edge of over the image. The technique resolved several test patterns independent of size and angle of rotation. Several samples obtained from different substrates were analyzed with the method. The results were consistent with those values obtained from conventional methods. Although still limited as a laboratory application, shape analysis has the potential to provide insight into the mechanisms of crystal growing and may provide a basis for specifications or guidelines for the manufacturing of biomaterial for bone tissue engineering. Our proposed automated computational method for the analysis and quantification digital images of bone tissue at microscale provide a rapid and accurate of the mechanical properties of the tissue.Fil: Tahoces, Pablo G.. Universidad de Santiago de Compostela; EspañaFil: Messina, Paula Verónica. Universidad Nacional del Sur; ArgentinaFil: Ruso, Juan Manuel. Universidad de Santiago de Compostela; Españ

Monoaminergic integration of diet and social signals in the brains of juvenile spadefoot toads

ABSTRACT Social behavior often includes the production of species-specific signals (e.g. mating calls or visual displays) that evoke context-dependent behavioral responses from conspecifics. Monoamines are important neuromodulators that have been implicated in context-dependent social behavior, yet we know little about the development of monoaminergic systems and whether they mediate the effects of early life experiences on adult behavior. We examined the effects of diet and social signals on monoamines early in development in the plains spadefoot toad (Spea bombifrons), a species in which diet affects the developmental emergence of species recognition and body condition affects the expression of adult mating preferences. To do so, we manipulated the diet of juveniles for 6 weeks following metamorphosis and collected their brains 40 min following the presentation of either a conspecific or a heterospecific call. We measured levels of monoamines and their metabolites using high pressure liquid chromatography from tissue punches of the auditory midbrain (i.e. torus semicircularis), hypothalamus and preoptic area. We found that call type affected dopamine and noradrenaline signaling in the auditory midbrain and that diet affected dopamine and serotonin in the hypothalamus. In the preoptic area, we detected an interaction between diet and call type, indicating that diet modulates how the preoptic area integrates social information. Our results suggest that the responsiveness of monoamine systems varies across the brain and highlight preoptic dopamine and noradrenaline as candidates for mediating effects of early diet experience on later expression of social preferences