Algunos datos históricos de Albardón a través de su patrimonio Ruiz, Viviana; Frau, Silvana Alejandra El departamento de Albardón se encuentra conformado por una cantidad importante de localidades y pueblos cargados de significado, "Las Tapias" es uno de ellos, vinculado con la fundación misma de la provincia de San Juan -1562-. Un pueblo histórico que formó parte de la historia activa de la provincia siendo un nudo en las rutas desde la fundación hasta 1930. Otros lugares históricos se han podido rescatar como la Estación Las Lomitas y la biblioteca San Martín, sitios donde el habitante albardonero se incorporó a la cultura, actividad económica y política provincial, regional y nacional. Como imaginario histórico se analiza el cruce del Río San Juan, barrera natural que separa a Albardón de la Ciudad de San Juan, un cruce cargado de significatividad para los habitantes de la región.

Géneros, significados sociales y prácticas discursivas del guaraní de Corrientes Cerno, Leonardo Aurelio Este trabajo expone algunas de las representaciones y símbolos que componen el imaginario sociocultural relativo al guaraní en comunidades rurales y pueblos del interior de la provincia de Corrientes, y vincula tales componentes con el sistema de usos observados y con prácticas de socialización lingüística específicas. A su vez describe y analiza un conjunto de categorías etnográficas referentes a tipos de hablantes y formas de conducta social relacionadas con el uso del guaraní, y ofrece una interpretación de tales nociones y prácticas teniendo en cuenta el horizonte sociocultural de los actores.

Personal assistants: Direct manipulation vs. mixed initiative interfaces Armentano, Marcelo Gabriel; Godoy, Daniela Lis; Amandi, Analia Adriana Interface agents are computer programmes that provide assistance to users dealing with computer-based applications. The introduction of agents to user interfaces caused the exploration of new metaphors to enhance user ability to directly manipulate interfaces. In this regard, mixed-initiative interaction refers to a flexible interaction strategy in which agents contribute with users by providing suitable information at the most appropriate time. Mixed-initiative approaches promise to dramatically enhance human-computer interaction by allowing agents to resemble human assistants. In this paper, we report a study on how the interaction metaphor can affect the user perception of agent capabilities and, in turn, the final success of agents.

Exploring RNA Virus Replication in Xenopus Oocytes Gamarnik, Andrea Vanesa; Andino, Raul Microinjection of poliovirus RNA in Xenopus oocytes initiates a complete and authentic viral replication cycle that yields newly synthesized infectious virus. This system can be used to study the molecular mechanism of the different steps involved in virus replication. Interestingly, viral replication only occurs if poliovirus RNA is coinjected with factors present in HeLa extracts. We have determined that two HeLa cell factors are required for viral replication in oocytes, one involved in initiation of translation (polio translation factor) and the other in RNA synthesis. Thus, microinjection in oocytes provides a strategy to identify and further analyze the function of these host cell factors and to biochemically dissect the mechanism of initiation of poliovirus translation and RNA synthesis. Here, we review protocols, approaches, and potential issues that can be addressed using the oocyte system.

Interactions Dans Les Dispersions. Stabilisation Quemada, Daniel; Berli, Claudio Luis Alberto Dans les dispersions et plus généralement dans les fluides complexes, les forces subies par les "particules" interviennent à trois niveaux: aux échelles microscopique, mésoscopique ou macroscopique. Nous les examinerons successivement aux § 2.1, 2.2 et 2.3. Remarquons que les forces à l?échelle microscopique peuvent être séparées en deux groupes: (i) les forces dites externes parce qu´elles résultent de l´action d´un agent extérieur à la suspension. Parmi ces agents, figure, en premier lieu, la pesanteur, qui entraîne une séparation de phase dès que les densités des deux composants de la dispersion sont suffisamment différentes. En second lieu, on trouve les champs électriques, si les particules sont chargées électriquement, ainsi que les champs magnétiques, si les particules sont magnétiques ou simplement chargées (i.e. équivalentes à un courant lorsqu?elles sont en mouvement). Ce sont les possibilités de contrôle des propriétés rhéologiques par l?action de ces champs qui ont donné naissance aux nouvelles classes de matériaux, fluides électro-rhéologiques et ferrofluides signalés dans l?introduction. (ii) les forces dites internes, qui sont des interactions agissant au niveau des particules et qui sont de deux types suivant que l?on se place en milieu très dilué (interaction ?fluide-particule?) ou en milieu semi-dilué ou en milieu concentré (interaction ?particule-particule?).

Relations Viscosite-Fraction Volumique Quemada, Daniel; Berli, Claudio Luis Alberto Nous commencerons donc par discuter dans ce chapitre les résultats des théories exactes, dans le cas des suspensions diluées, en nous appuyant sur les calculs de Batchelor (§4.1), puis nous donnerons un aperçu des possibilités de développement de théories exactes pour les milieux très concentrés, mais néanmoins en essayant d?en montrer les limites lorsqu?on tente de les appliquer à de tels milieux (§4.2). Ensuite, les modèles phénoménologiques, certains directement déduits de plusieurs extensions de la loi d?Einstein, seront présentés et discutés (§4.3), le concept de structure mésoscopique dont la taille dépend de l?écoulement se dégageant progressivement. Enfin, le modèle directement déduit du modèle de SD et prenant en compte les effets de la compacité des structures sera développé (§4.4). On ne discutera pas du très grand nombre de relations purement empiriques (pour lesquelles il existe une revue assez exhaustive [Rutgers, 1962]), dans lesquelles interviennent des paramètres dont l?interprétation n?est pas toujours claire. Il en sera de même de certaines "lois" sous lesquelles sont regroupées un très grand nombre de données expérimentales (cf. par ex. [Thomas, 1961]).

Estrogens and neuroendocrine hypothalamic-pituitary-adrenal axis function de Nicola, Alejandro Federico; Saravia, Flavia Eugenia; Beauquis, Juan; Pietranera, Luciana; Ferrini, Monica G. The function of the HPA axis is subject to regulation by many factors, which achieve relevance under normal and pathological conditions. In the case of aging, this period of life is associated with disturbances of the HPA axis and signs of hippocampal vulnerability. We examined 20-month-old male rats, in which abnormalities of the HPA axis included altered response to stress, reduced effectiveness of the steroid negative feedback and low expression of hippocampal glucocorticoid receptors (GR). Estrogen treatment of aging rats normalized the response to stress, restored the dexamethasone inhibition of the stress response and increased GR density in defined hippocampal areas. Although estrogens could influence the hippocampus of aging animals directly, their effects could be also mediated by estrogen-sensitive forebrain cholinergic neurons projecting to the hippocampus. Additionally, estrogens normalized the deficient granule cell proliferation that aging mice present in the dentate gyrus, and attenuated several markers of hippocampal aging, such as astrocytosis, high lipofucsin content and neuronal loss in the hilus of the dentate gyrus. These effects may be important for the regulation of the HPA axis, in the context that hippocampal function as a whole was normalized by estrogen action. Therefore, estrogens are powerful neuroprotectants in cases of hippocampal dysfunction, and as part of this effect, they contribute to stabilize the function of the HPA axis.

Vegetación Menghi, Mirta Melva Mercedes Las primeras descripciones de la vegetación de Mar Chiquita provienen de Federico Kurtz en la Geografia de la provincia de Córdoba de Ríos & Achaval (1904), y del mapa fitogeográfico que  Kanter (1935) publica como parte de un análisis geográfico detallado de la cuenca de Mar Chiquita. En su obra sobre la vegetación del norte de Córdoba, Sayago (1969) realizó un estudio amplio y detallado de la vegetación de Mar Chiquita y los bañados del Río Dulce, el cual incluye un mapa de la vegetación a escala 1:400000. Este relevamiento se llevó a cabo en un período previo a las grandes inundaciones iniciadas a fines de la década de 1970. Posteriormente  Luti et al. (1979) elaboraron una nueva revisión de la vegetación del área. Mas recientemente Menghi & Herrera (1995; 1996) analizaron en detalle la diversidad florística y aspectos funcionales de la vegetación de la depresión de Mar Chiquita, así como la relación con el relieve y la hidrología (del Sueldo 1995) y con la producción primaria en bañados del Río Dulce (Menghi & Herrera 1998; Menghi et al. 2003).

Automated method for the total creatinine determination in dehydrated broths Acebal, Carolina Cecilia; Centurión, María Eugenia; Lista, Adriana Guillermina; Fernández Band, Beatriz Susana In order to improve the quality control of dehydrated broth, a new automated method was developed to determine total creatinine in dehydrated broths. The sample pretreatment was coupled on-line with the Flow Injection Analysis (FIA) system for analyte determination by the classical Jaffe reaction, stopped flow methodology, and spectrophotometric detection. The time consumed was reduced from 7h, which is necessary with the official method, to 25 min. The calibration graph is linear between 0.342-1.368 mg creatinine/ 100 mL. The relative standard deviation (RSD%) was 1.7%, the sample throughput was 7 h -1, and the detection limit was 0.185 mg creatinine/100 mL. The validation of the proposed method was carried out with real samples. The obtained results were compared with those obtained from the Association of Official Analytical Chemists (AOAC) reference method.

Ostracods (Crustacea) from thermal waters, southern Altiplano, Argentina Laprida, Cecilia; Diaz, Analia Roxana; Ratto, Norma Rosa The ostracod fauna from la Terma hot spring (26°55′31″ S - 68°08′45.7″W, 4026m above sea level), Southern Altiplano, Argentina, is described and the pool itself characterized. The occurrence of ostracods in this type of environments is registered for the first time in Argentina. Six species were found, two of which are new to the fauna of Argentina: Penthesilenula incae (Delachaux) and Hemicypris panningi (Brehm). Two species were found for the first time in the Altiplano: H. panningi (Brehm) and Cypridopsis fuhrmanni (Méhes). Some comments concerning how and when these species could spread to populate the Dry Altiplano are discussed briefly taking into account paleoclimatic data. This paper provides the first record of recent ostracods from the Southern Altiplano, Argentina.

Administration of corticosterone after the first downshift trial enhances consummatory successive negative contrast Bentosela, Mariana; Muzio, Ruben Nestor; Ruetti, Eliana Martha; Mustaca, Alba Elisabeth; Papini, Mauricio Roberto Rats given access to a 32% sucrose solution and then downshifted to a 4% solution exhibit less contact with the sipper tube than unshifted controls always given access to 4% solution. This phenomenon, called consummatory successive negative contrast, was facilitated in Experiment 1 by a post-trial injection of corticosterone (3 mg/kg) administered immediately after the first downshift trial. Experiment 2 demonstrated that this facilitatory effect of post-trial corticosterone does not occur when administered 3 hr after the first downshift trial. These results support the hypothesis that corticosterone strengthens an aversive emotional component elicited by the surprising downshift in reward magnitude during the initial downshift trial.

A kinetic study on the inhibitory action of sympathomimetic drugs towards photogenerated oxygen active species: The case of phenylephrine Massad, Walter Alfredo; Bertolotti, Sonia Graciela; Romero, Mario Raul; Garcia, Norman Andino Kinetics and mechanism of the aerobic Riboflavin (Rf, vitamin B2) sensitized photodegradation of Phenylephrine (Phen), a phenolamine belonging to the sympathomimetic drugs family, has been studied in water, employing continuous photolysis, polarographic detection of oxygen uptake, steady-state and time-resolved fluorescence spectroscopy, time-resolved IR-phosphorescence and laser flash photolysis. Results indicate the formation of a weak dark complex Rf–Phen, with an apparent association constant of 5.5 ± 0.5 M 1 , only detectable at Phen concentrations much higher than those employed in the photochemical experiments. Under irradiation, an intricate mechanism of competitive reactions operates. Phen quenches excited singlet and triplet states of Rf, with rate constants of 3.33 ± 0.08 and 1.60 ± 0.03 · 109 M 1 s 1 , respectively. With the sympathomimetic drug in a concentration similar to that of dissolved molecular oxygen in water, Phen and oxygen competitively quench triplet excited Rf, generating superoxide radical anion and singlet molecular oxygen (O2( 1 Dg)) by processes initiated by electron- and energy-transfer mechanisms respectively. As a global result, the photodegradation of the vitamin, a known process taking place from its excited triplet state, is retarded, whereas the phenolamine, practically unreactive towards these oxidative species, behaves as a highly efficient physical deactivator of O2( 1 Dg). The phenolamine structure in Phen appears as an excellent scavenger of activated oxygen species, comparatively superior, in kinetic terms, to some commercial phenolic antioxidants.

Effect of the drug-excipient ratio in matrix-type-controlled release systems: Computer simulation study Villalobos, Rafael; Ganem, Adriana; Cordero, Salomón; Vidales, Ana Maria; Domínguez, Armande The main objective of this work is to study the drug release behavior from inert matrix systems by using computer simulation. This study allowed us to propose a new statistical method to evaluate the drug percolation threshold as a function of the exposed surface area of the device. The matrix system was simulated as a simple cubic lattice. The sites of the lattice were randomly occupied at various drug-excipient ratios. By simulating a diffusive process, the drug was delivered from the matrix system. The obtained release profiles were fitted to two different models: near the excipient percolation threshold, the square root of the time was well fitted, whereas close to (but above) the drug percolation threshold, the power law described accurately the release data. A relationship between the initial drug load and the amount of drug trapped inside the matrix system at infinite time was found. This relationship was conveniently described by an error function. Percolation thresholds in the matrix systems were determined from the latter relationship by using a nonlinear regression method. The assessment of percolation thresholds depends on the exposed surface area of the matrix systems. Moreover, estimated percolation thresholds were in agreement with the predicted values stated in the percolation theory.

The natural vector bundle of the set of multivariate density functions Marchi, Ezio; Morillas, Patricia Mariela We find a description of the set of multivariate density functions with given marginals and introduce an associated vector bundle. The interest for the probability theory is restricted to the nonnegative elements in the sets of the derived vector bundle. The fiber is the space of all correlation measures among a multivariate density function and its unidimensional marginals.

Stability of Araujiain, a novel plant protease, in different organic systems; Estabilidad de Araujiaína, una nueva fitoproteasa, en diferentes sistemas orgánicos Quiroga, Evelina; Priolo, Nora Silvia; Marchese, Jose; Barberis, Sonia Esther The effect of different organic solvents on the stability of araujiain(the crude enzyme preparation obtained from the latex of fruits of Araujia hortorum Fourn., Asclepiadaceae) in mixtures of buffer and different water-miscible or immiscible organic solvents, and in continuous systems (organic solvents with low water activity) after 4 h at 40 ºC was studied in this paper in order to select the most adequate media for peptide enzymatic synthesis. Araujiainshowed the highest stability in 50% hexane, 50% propanone, and N,N-dimethylformamide (aw: 0.5 in the enzyme), and those values were remarkably greater than in buffer. In addition, the presence of those organic solvents reduced the autolysis degree. In general, araujiainwas not inactivated in aqueous-miscible organic systems and the enzyme showed higher activities in those media than in buffer. In biphasic systems, the partition of the organic solvents into the aqueous phase activated the enzyme in several cases. These results did not agree with those obtained in continuous systems, because many of them inactivated the enzyme. Nevertheless, in N,N-dimethylformamide (aw: 0.5 in the enzyme) araujiainshowed a remarkable stability after 4 h, and it displayed a higher activity in this organic solvent than in aqueous medium. From these results, it is evident that araujiain in the presence of most of the studied organic systems did not suffer unfolding and it was able to retain its native or native-like configuration, though with altered characteristics or properties. This fact was demonstrated by means of comparative FTIR spectroscopy studies for araujiainin buffer and non-aqueous systems.; Con el objeto de seleccionar los medios más adecuados para la síntesis enzimática de péptidos, estudiamos el efecto de diferentes solventes orgánicos sobre la estabilidad de araujiaina(la preparación enzimática no purificada obtenida del látex de frutos de Araujia hortorumFourn., Asclepiadaceae) en mezclas de buffer y diferentes solventes orgánicos miscibles o inmiscibles con el agua y en sistemas continuos (solventes orgánicos con baja actividad de agua), luego de 4 h a 40 °C. Araujiainamostró la mayor estabilidad en hexano (50%), propanona (50%) y en N,N-dimetilformamida (aw: 0,5 en la enzima), siendo aquellos valores marcadamente más elevados que en buffer. Además, la presencia de aquellos solventes orgánicos redujo el grado de autólisis. En general, en sistemas miscibles araujiainano fue inactivada, mostrando actividades más altas que en buffer. En sistemas bifásicos, la partición de los solventes orgánicos en la fase acuosa produjo en numerosos casos una considerable activación de la enzima. Por el contrario, la mayoría de los sistemas continuos inactivaron la enzima. Sin embargo, en N,N-dimetilformamida (aw: 0,5 en la enzima) araujiaina fue estable luego de 4 h y más activa que en medio acuoso. De los resultados aquí presentados hay evidencias de que araujiainano sufrió desdoblamiento en presencia de la mayoría de los sistemas orgánicos estudiados y fue capaz de retener su conformación nativa o semejante a la nativa pero con características o propiedades alteradas. Este hecho fue demostrado por medio de estudios comparativos de espectroscopía FTIR para araujiainaen buffer y en sistemas no acuosos.

A particle swarm optimizer for multi-objective optimization Cagnina, Leticia Cecilia; Esquivel, Susana Cecilia; Coello Coello, Carlos This paper proposes a hybrid particle swarm approach called Simple Multi-Objective Particle Swarm Optimizer (SMOPSO) which incorporates Pareto dominance, an elitist policy, and two techniques to maintain diversity: a mutation operator and a grid which is used as a geographical location over objective function space. In order to validate our approach we use three well-known test functions proposed in the specialized literature. Preliminary simulations results are presented and compared with those obtained with the Pareto Archived Evolution Strategy (PAES) and the Multi-Objective Genetic Algorithm 2 (MOGA2). These results also show that the SMOPSO algorithm is a promising alternative to tackle multiobjective optimization problems.

La configuración del poder en los espacios de trabajo: Dispositivos disciplinarios y resistencia de los trabajadores Montes Cato, Juan Sebastian El artículo analiza las relaciones de poder en los espacios de trabajo en Argentina durante la década de lo noventa. Para ello se seleccionó el sector de las empresas de telecomunicaciones como caso testigo. Nos interesa resaltar la articulación existente entre la flexibilización laboral y los diversos dispositivos de disciplinamiento. Esto permitirá analizar la configuración adoptada por los procesos de dominación del capital. Puesto que las relaciones laborales son esencialmente conflictivas, se estudian las acciones de resistencia desde una perspectiva que recupera aquellos aspectos materiales como los simbólicos. El estudio concluye que el denominado “proceso de modernización” implicó mayor precarización en las condiciones de trabajo y una profundización de la explotación de la fuerza de trabajo.; This article analyses the relations of power in the workplace in Argentina during the decade of the nineties. For it witness selected the sector of the companies of telecommunications. We are interested in highlighting the existing joint the labour flexibility and discipline at work. This will along to analyse the configuration adopted as a processes of domination. Since labour relations are essentially conflict, the actions of resistance are studied from a perspective that recovers those material aspects as the symbolic ones. The study concludes that called “process of modernization” involved major vulnerability in work conditions and a deepening of the exploitations of workforce.

A South American bioinvasion case history: Limnoperna fortunei (Dunker, 1857), the golden mussel Darrigran, Gustavo Alberto; Damborenea, Maria Cristina Two factors combine in this age of globalization to favor the establishment of alien species in natural environments: human activities and global climate change. This paper reviews the recent invasion of the golden mussel, Limnoperna fortunei, in South America, including its impacts in natural and human environments. This case study allows the identification of the likely impacts that morphologically and functionally similar invasive species will have in similar environments, such as in North America, which is considered to be at high risk of invasion by L. fortunei.

The radical-based reduction with (TMS)3SiH 'on water' Postigo, Jose Alberto; Ferreri, Carla; Navacchia, Maria Luisa; Chatgilialoglu, Chryssostomos Reduction of different organohalides, bromonucleosides among them, was successfully carried out in yields ranging from 75% to quantitative, using (TMS)3SiH in a heterogeneous system with water as the solvent. Our procedure, employing 2-mercaptoethanol as the catalyst and the hydrophobic diazo-compound ACCN as the initiator, illustrates that (TMS)3SiH can be the radical-based reducing agent of choice in aqueous medium. (TMS) 3SiH does not suffer from any significant reaction with water and can safely be used with additional benefit, such as ease of purification and environmental compatibility.

Orexin A stimulates hypothalamic-pituitary-adrenal (HPA) axis function, but not food intake, in the absence of full hypothalamic NPY-ergic activity Moreno, Griselda Noemí; Perello, Mario; Gaillard, Rolf C.; Spinedi, Eduardo Julio Neonatal monosodium L-glutamate (MSG) treatment destroys hypothalamic arcuate nucleus neuronal bodies, thus inducing several metabolic abnormalities. As a result, rats develop a phenotype characterized by hyperleptinemia and by impaired NPY but normal preproorexin hypothalamic mRNAs expression. Thus, our study was designed to explore whether hypothalamic effects of orexin A on food intake and glucocorticoid production develop in the absence of full hypothalamic NPY-ergic activity. For this purpose we evaluated, in control and MSG-treated rats, the consequences of intracerebroventricular (icv) orexin A administration on food intake and changes in circulating levels of ACTH and glucocorticoid. Our results indicate that orexin A icv treatment stimulated hypothalamic-pituitary-adrenal (HPA) axis activity in both MSG-damaged and normal animals, with this response even more pronounced in neurotoxin-damaged rats. Conversely, food intake was only enhanced by icv orexin A injection in normal rats. Our study further supports that acute hypothalamic effects of orexin A on food intake and glucocorticoid production are due to independent neuronal systems. While intact arcuate nucleus activity is needed for the orexinergic effect induced by icv orexin A administration, conversely, orexin A-stimulated HPA axis function takes place even in the absence of full NPY-ergic activity.