Relaciones potenciodinámicas corriente/potencial para la formación electroquímica de capas yuxtapuestas; Potentiodynamic current/potential relationships for electrochemical formation of yuxtaposed layers Moreno, Dora Elia; Sustersic, Maria Gisela El objetivo de este trabajo es analizar y comparar las distintas propuestas teóricas presentadas para la formación electroquímica de monocapas y capas yuxtapuestas. Se estudia la variación del grado de cubrimiento de la superficie del electrodo en función del tiempo en la electroadsorción para procesos reversibles. El modelo básico considerado es el de Sirinivasan-Gileadi. Este ha sido ampliado por acoplamiento de un proceso de disolución química y por la participación de una resistencia óhmica. Recientemente se ha elaborado un modelo de formación de multicapas, aplicando las ecuaciones de Srinivasan-Gileadi a cada una de ellas, teniendo en cuenta la resistencia ohmica que cada capa opone al paso de corriente. Se analiza, además de la ley de cubrimiento superficial, el comportamiento de la relación corriente/potencial en los casos de monocapas y capas yuxtapuestas con o sin resistencia óhmica, mostrándose su influencia en el potencial del máximo.; The objective of this work is to analyze and to compare different models for electrochemical formation of mono and yuxtaposed-layer. In particular, the variation of electrode surface coverage as a function of time is studied for electro-adsorption in reversible reactions. The basic model is that of SrinivasanGileadi. This has been extended by coupling a chemical dissolution process and an ohmic resistance. A model for multi-layers formation elaborated taking into account the Srinivasan-Gileadi model for each of them and considering the ohmic resistance that each layer opposes to the electrical current has also been analyzed. Besides the surface coverage law, the behavior of the current/potential relation in the cases of mono and yuxtaposed-layers with and without ohmic resistance are considered. The influence of these variables in the peak potential is shown.

Regional geoid determination in Tierra del Fuego including GPS levelling del Cogliano, Daniel Hector; Dietrich, R.; Richter, Andreas Jorg; Perdomo, Raul Anibal; Hormaechea, José Luis; Liebsch, G.; Fritsche, M. A regional geoid model for the Argentine part of the Isla Grande de Tierra del Fuego, established in previous works on the basis of GPS levelling, suffers a lack of observation data in the remote south-western investigation area. In order to improve the data distribution in this region, the mean lake level of Lago Fagnano has been regarded as a natural indicator for the local geoid. Using a GPS buoy and pressure tide gauges, a method to determine the mean lake surface topography with respect to the ellipsoid has been developed. It is shown thatthe obtained lake level geometry is essentially controlled by the regional gravity field. The derived information on the mean lake level has been included in the geoid model, which results in a more detailed and plausible representation of the regional geoid.

El efecto ansiolítico de testosterona en ratas macho no se debe a la aromatización de estrógeno: evidencias preliminares Yunes, Roberto Miguel Federico; Boulin F.; Cabrera Kreiker, Ricardo Jorge Se sabe que testosterona (T) y sus metabolitos dihidrotestosterona y 3œandrostanediol presentan propiedades ansiolíticas en modelos animales de ansiedad. Sin embargo, y dado que T puede ser aromatizada a estradiol (E2), no se puede descartar un rol ansiolítico de este último compuesto orgánico. En este trabajo, mediante la utilización de ratas macho intactas y castradas, y empleando T o E2 como terapia de reemplazo, pudimos comprobar que E2 no posee efectos ansiolíticos, en tanto sí están presentes posterior a la impregnación con T o eventualmente con sus metabolitos no aromatizables; It has been reported that testosterone (T) and its metabolites dihydrotestosterone and 3œ-androstanediol exhibit anxiolytic properties. However, and since T is also usually aromatized to estradiol (E2), it has not been ruled out the possibility of E2 being responsible for the aforementioned effect, at least partially. In this report, by using intact and castrated male rats, with or without E2 or T replacement, we could conclude that the anxiolytic effect is not due to E2 but to T and, eventually its non aromatizable metabolites.

In Vivo Crosslinking Methods for Analyzing the Assembly and Architecture of Chemoreceptor Arrays Studdert, Claudia Alicia; Parkinson, John S. The chemoreceptor molecules that mediate chemotactic responses in bacteria and archaea are physically clustered and operate as highly cooperative arrays. Few experimental approaches are able to investigate the structure-function organization of these chemoreceptor networks in living cells. This chapter describes chemical crosslinking methods that can be applied under normal physiological conditions to explore physical interactions between chemoreceptors and their underlying genetic and structural basis. Most of these crosslinking approaches are based on available atomic structures for chemoreceptor homodimers, the fundamental building block for higher-order networks. However, the general logic of our in vivo crosslinking approaches is readily applicable to other protein-protein interactions and other organisms, even when high-resolution structural information is not available.

A new species of Uristes Dana, 1849 (Amphipoda: Lysianassoidea: Uristidae) from the Beagle Channel, Argentina Chiesa, Ignacio Luis; Alonso, Gloria Maria A new species of Uristes Dana, 1849 (Uristidae) collected from shallow waters in the Beagle Channel, Argentina, is described and illustrated. Uristes yamana n. sp., the third species of this genus reported for the Magellan area, is closely related to U. serratus Schellenberg 1931, principally by the possession of an unusual stout gnathopod 1 propodus. Both species can be separated by telson shape and relative setosity of uropod 3. The geographical distribution of U. gigas Dana 1849 is also emended.

Pobreza y salud en la Argentina: descripción de una relación asimétrica en base a la Encuesta de Condiciones de Vida del año 2001 Bergesio, Liliana del Carmen; Golovanevsky, Laura Andrea El trabajo muestra la inequidad en cuestiones de salud en la República Argentina, a partir de la comparación de regiones geográficas. Para ello se realiza un análisis de la relación entre conductas vinculadas a la salud y pobreza de los hogares, en base a microdatos de la Encuesta de Condiciones de Vida del año 2001 (ECV-2001). Se concluye que la relación entre pobreza y salud tiene una variedad de aspectos y connotaciones que la tornan muy compleja, presentándose los efectos de la pobreza sobre las condiciones de salud de niños, mujeres y dificultades de accesibilidad como los más relevantes. Para la Argentina, el principal problema es que los servicios y la cobertura de la salud pública son deficitarios y fuertemente inequitativos, desatendiendo a los más pobres (sean estos individuos o regiones).; The work shows the inequity in health issues in the Argentine Republic, based on the comparison of geographical regions. To do this, an analysis of the relationship between behaviors related to health and poverty in households is carried out, based on microdata from the 2001 Survey of Living Conditions (ECV-2001). It is concluded that the relationship between poverty and health has a variety of aspects and connotations that make it very complex, presenting the effects of poverty on the health conditions of children, women and accessibility difficulties as the most relevant. For Argentina, the main problem is that public health services and coverage are deficient and strongly inequitable, neglecting the poorest (be they individuals or regions).

Análisis paleoambiental sobre la base del estudio malacológico del sitio Paso Otero 1 (región pampeana, Argentina); Paleoenvironmental Analysis of the Malacological Studies Conducted at paso Otero 1 Site (Pampean Region, Argentina) Steffan, Pamela Guillermina Se infieren las condiciones paleoclimáticas y paleoambientales en Paso Otero 1 durante el Holoceno, particularmente desde los ca. 4800 AP a 2900 años AP. Paso Otero 1 está ubicado en el área del curso medio del río Quequén Grande (área Interserrana Bonaerense, región pampeana). El análisis de la composición de la fauna de gasterópodos comprende distintos aspectos: diversidad de especies representadas en el muestreo, medidas de abundancia relativa de individuos por especie y distribución de frecuencias por niveles muestreados. Los resultados indican una mayor humedad hacia los 4800 años AP y un ascenso en la temperatura hacia los 2900 años AP. Estos análisis permitieron evaluar la información paleoambiental de los gasterópodos fósiles y aportar datos acerca de las condiciones ambientales locales.; In this paper, paleoclimatic and paleoenvironmental conditions at Paso Otero 1 are inferred for the Holocene, particularly from ca. 4800 to 2900 BP. Paso Otero 1 is located in the area of the middle basin of the Quequén Grande river (Interserrana Bonaerense area, Pampean region). Analysis of the faunal composition of gastropod fauna included different aspects: diversity of represented species in the sample, measurements of relative abundance of individuals by species, and the distribution of frequencies for sampled levels. The results indicate greater humidity toward ca. 4800 BP and an increase in temperature toward 2900 BP. The analyses enable the environmental information of the fossil gastropods to be evaluated, contributing data on local environmental conditions.

Explosion time in stochastic differential equations with small diffusion Groisman, Pablo Jose; Rossi, Julio Daniel We consider solutions of a one dimensional stochastic differential equations that explode in finite time. We prove that, under suitable hypotheses, the explosion time converges almost surely to the one of the ODE governed by the drift term when the diffusion coefficient approaches zero.

The best Sobolev trace constant in a domain with oscillating boundary Fernandez Bonder, Julian; Orive, Rafael; Rossi, Julio Daniel In this paper we study homogenization problems for the best constant for the Sobolev trace embedding W1, p (Ω) {right arrow, hooked} Lq (∂ Ω) in a bounded smooth domain when the boundary is perturbed by adding an oscillation. We find that there exists a critical size of the amplitude of the oscillations for which the limit problem has a weight on the boundary. For sizes larger than critical the best trace constant goes to zero and for sizes smaller than critical it converges to the best constant in the domain without perturbations.

On the embedding problem for 2+s4 representations Pacetti, Ariel Martín Let 2+S4 denote the double cover of S4 corresponding to the element in H2(S4, Z/2Z) where transpositions lift to elements of order 2 and the product of two disjoint transpositions to elements of order 4. Given an elliptic curve E, let E[2] denote its 2-torsion points. Under some conditions on E elements in H1(GalQ, E[2])\{0} correspond to Galois extensions N of Q with Galois group (isomorphic to) S4. In this work we give an interpretation of the addition law on such fields, and prove that the obstruction for N having a Galois extension N˜ with Gal(N/˜ Q) 2+S4 gives a homomorphism s+ 4 : H1(GalQ, E[2]) → H2(GalQ, Z/2Z). As a corollary we can prove (if E has conductor divisible by few primes and high rank) the existence of 2-dimensional representations of the absolute Galois group of Q attached to E and use them in some examples to construct 3/2 modular forms mapping via the Shimura map to (the modular form of weight 2 attached to) E.

Los Salesianos y la conquista de la Patagonia: desde Don Bosco hasta sus primeros textos escolares e historias oficiales; The Salesians and the Conquest of the Patagonia: From Don Bosco to their first school texts and official history records Nicoletti, Maria Andrea La Congregación Salesiana de Don Bosco llegó a la Argentina en 1875 con la intención de evangelizar “infieles” en la Patagonia, mediante un plan concreto de adoctrinamiento y educación para los pueblos originarios. Para ello, Don Bosco formuló un proyecto en el que el daba cuenta acerca de la situación violenta entre los indígenas y el Estado argentino en Patagonia. Tras algunos intentos fallidos de ingresar a la Patagonia, los Salesianos acompañan al ejército de Julio Roca en 1879. Este suceso fue narrado por los primeros misioneros como un hecho cruel y violento perpetrado por el ejército, al que criticaron fuertemente, narrando la situación de marginalidad, pobreza y exclusión de los sobrevivientes. Sin embargo, justificaron esta acción en función de la “acción civilizadora” del Estado y la “necesidad” de cristianización de sus habitantes. Estas primeras fuentes se fueron reinterpretando en distintos textos salesianos: desde los informes internos (Anales) hasta sus propios los textos escolares y sus narraciones históricas. Cada fuente seleccionó y justificó esta información de primera mano de acuerdo al lector, el contexto historiográfico y a su propia reelaboración sobre este tema clave: la violencia y la evangelización.; The Salesian Congregation of Don Bosco arrived in Argentina in 1875 with the aim of evangelizing “infidels” in the Patagonia with a specific plan of indoctrination and education for the originary people. For this purpose, Don Bosco formulated a project where he stated the violent situation between the indigens and the Argentinean state in Patagonia. After some unsuccessful attempts of entering the Patagonia, the Salesians went along with the army of Julio Roca in 1879. This event was narrated by the first missioners as a cruel and violent action perpetrated by the army, which they criticized heavily, telling about the situation of marginality, poverty and exclusion of the survivors. However, they justified this action according to the “civilizing action” of the State and the “necessity” of Christianization of its inhabitants. These first sources have been reinterpreted in different Salesian texts: from the internal reports (Annals) to their own school texts and historical narrations. Each source selected and justified this first-hand information according to the reader, the historiographical context and their own re-elaboration of this key subject: violence and evangelization.

Hb Alesha [β67(E11)Val→Met, GTG→ATG] in an Argentinean girl Eberle, Silvia Eandi; Noguera, Nelida Ines; Sciuccati, Gabriela; Bonduel, Mariana; Díaz, Lilian; Staciuk, Raquel; Targovnik, Hector Manuel; Feliu Torres, Aurora Hb Alesha is caused by a GTG>ATG mutation at codon 67 of the b-globin gene, resulting in abnormal beta-globin chains in which the normal beta67(E11) valine is changed to methionine. This hemoglobin (Hb) is also known as Hb Bristol, the first unstable Hb described, since in a fraction of the variant the methionine is modified into an aspartic acid by a posttranslational modification. This replacement disrupts the apolar bonds between the valine and the heme group, producing an unstable Hb and severe hemolysis. We have identified this rare hemoglobinopathy in an Argentinean girl with severe hemolytic anemia, splenomegaly and frequent requirement for red blood cell transfusions.

Rafael Bielsa y la conformación de un nuevo modelo de formación científica universitaria de Marco, Miguel Angel L. El presente artículo se enmarca en el abordaje biográfico del doctor Rafael Bielsa efectuado en el marco del Proyecto "Juristas, Derecho y Sociedad en la Argentina contemporánea. Ideas y mentalidades de los operadores jurídicos (1901-1970)", del Instituto de Investigaciones en Historia del Derecho. Siguiendo un camino abierto por el doctor Víctor Tao Anzoátegui en la década del 70, se profundiza en la obra de Rafael Bielsa en su prédica por la superación del positivismo, el fomento de los estudios jurídicos y sus iniciativas en reformar el sistema jurídico. Analiza la influencia de lo regional en la visión de Bielsa y sus propuestas superadoras de la Reforma Universitaria, poniendo a la luz el valioso contenido de las actas del Consejo Directivo de la Facultad de Ciencias Económicas, Comerciales y Políticas y del Colegio de Abogados de Rosario. La primera parte se refiere a la incidencia de la Facultad de Ciencias Económicas, Comerciales y Política en la formación de recursos para la región; la segunda, al decanato de Rafael Bielsa y la proyección internacional de la Facultad; la tercera, a la situación en tiempos de intervenciones nacionales y el Golpe de Estado de 1930; la cuarta parte: al breve rectorado de Bielsa al frente de la Universidad Nacional del Litoral y su tercer decanato; la quinta parte: a la consolidación de los flamantes institutos de investigación; y la sexta parte, al cuarto decanato de Bielsa, coincidente con el inicio de la década del 40. El relevamiento de actas concluye en 1943, cuando un nuevo golpe de Estado implicó un cambio de rumbo en la política universitaria argentina.

Infection by Rickettsia bellii and Candidatus "Rickettsia amblyommii" in Amblyomma neumanni ticks from Argentina Labruna, Marcelo B.; Pacheco, Richard C.; Nava, Santiago; Brandão, Paulo E.; Richtzenhain, Leonardo J.; Guglielmone, Alberto Alejandro The tick species, Amblyomma neumanni (Acari: Ixodidae) is the most frequent tick parasitizing humans in northwestern Argentina. The present study evaluated the rickettsial infection among 55 A. neumanni adult free-living ticks collected in Dean Funes, Córdoba Province. Ticks were individually processed by the hemolymph test with Gimenez staining, isolation of rickettsia in Vero cell culture by the shell vial technique, and polymerase chain reaction (PCR) targeting the citrate synthase rickettsial gene. Through the shell vial technique, rickettsiae were successfully isolated and established in Vero cell culture from two ticks (ticks 4 and 13), which previously showed to contain Rickettsia-like organisms by the hemolymph test. These two Rickettsia isolates were designated as An4 and An13. Molecular characterization (partial DNA sequences of two to three rickettsial genes were determined) of these two isolates and phylogenetic analyses identified them as Rickettsia bellii (isolate An4) and Candidatus "Rickettsia amblyommii" (isolate An13). After testing all A. neumanni ticks by PCR, the prevalence of Candidatus R. amblyommii and R. bellii was 23.6% (13/55) and 3.6% (2/55), respectively. These two rickettsiae have been considered of unknown pathogenicity and appropriate studies to test their pathogenicity to humans or animals need to be conducted. This is the first report of Rickettsia in ticks from Argentina, and also in the species A. neumanni. The results reinforce previous findings that R. bellii (and probably Candidatus R. amblyommii) are widespread among some Neotropical Amblyomma species, suggesting that these ticks gained these bacterial agents from a common ancestor and/or by recent horizontal transmission of rickettsiae between ticks.

Phosphorous amount in floating and rooted macrophytes growing in wetlands from the Middle Paraná River floodplain (Argentina) Hadad, Hernán Ricardo; Maine, Maria Alejandra Biomass, P concentration, P amount and chlorophyll in three floating and three rooted macrophytes growing in wetlands of the Middle Paraná River floodplain measured in winter and summer were compared. Macrophytes were sampled three times in summer and twice in winter, in the period 2002/2004. Although Pistia stratiotes was the species with the highest P concentration in leaves and roots, Typha domingensis, Eichhornia crassipes and Pontederia cordata were the most efficient species in P retention in natural wetlands because of their higher biomass. Total P amount in rooted species did not show seasonal variations. However, T. domingensis accumulated a greater P amount in its aerial part in summer, whereas in winter it did so in its below-ground parts, indicating an important P dynamic regarding translocation within the plant. In summer, floating species were able to accumulate great quantities of P in a short period due to their high growth rate. In order to optimize and maintain the efficiency of constructed wetlands for P removal throughout the year, a selection of floating and rooted species should be used.

Effects of enzymatic treatment on cellulosic fibres from recycled paper. Analysis of the experimental design Taleb, María Claudia; Maximino, Mirta Graciela An enzymatic preparation consisting of cellulases and hemicellulases significantly affected the drainability and strength properties of an unbleached softwood Kraft pulp repulped in laboratory. The independent variables, treatment time and enzyme dose, were analysed using a central composite design for both the whole pulp and its fibrous fractions. Statistical analysis showed significant improvements in drainability. The effects of enzymatic treatments on strength properties were: increase in tensile index and apparent density and decrease in tear index and light scattering coefficients. Changes in fibre surfaces (initial and with enzyme treatment) could be observed by Simons´ differential stain.

Influence of residual milk-clotting enzyme and proteolysis on melting properties of soft cheese Candioti, Mario César; Alonso, María Jimena; Hynes, Erica Rut In this work, we assessed the influence of coagulant residual activity and primary proteolysis on Cremoso Argentino cheese melting properties. For that purpose, we made Cremoso soft cheeses using different amounts of coagulant, and also obtained samples in which milk clotting enzyme was inactivated. The residual activity of coagulant correlated with primary proteolysis, especially in early stages of ripening. Caseins’ hydrolysis did not significantly impact on the melting ability of the cheeses, expressed as the area increase after heating samples under standardised conditions. Samples with similar proximate composition showed some changes in meltability; those seemed related to pH evolution during ripening.

Protective action of Lactobacillus kefir carrying S-layer protein against Salmonella enterica serovar Enteritidis Golowczyc, Marina Alejandra; Mobili, Pablo; Garrote, Graciela Liliana; Abraham, Analia Graciela; de Antoni, Graciela Liliana Eight Lactobacillus kefir strains isolated from different kefir grains were tested for their ability to antagonize Salmonella enterica serovar Enteritidis (Salmonella enteritidis) interaction with epithelial cells. L. kefir surface properties such as autoaggregation and coaggregation with Salmonella and adhesion to Caco-2/TC-7 cells were evaluated. L. kefir strains showed significantly different adhesion capacities, six strains were able to autoaggregate and four strains coaggregated with Salmonella. Coincubation of Salmonella with coaggregating L. kefir strains significantly decreased its capacity to adhere to and to invade Caco-2/TC-7 cells. This was not observed with non coaggregating L. kefir strains. Spent culture supernatants of L. kefir contain significant amounts of S-layer proteins. Salmonella pretreated with spent culture supernatants (pH 4.5–4.7) from all tested L. kefir strains showed a significant decrease in association and invasion to Caco-2/TC-7 cells. Artificially acidified MRS containing lactic acid to a final concentration and pH equivalent to lactobacilli spent culture supernatants did not show any protective action. Pretreatment of this pathogen with spent culture supernatants reduced microvilli disorganization produced by Salmonella. In addition, Salmonella pretreated with S-layer proteins extracted from coaggregating and non coaggregating L. kefir strains were unable to invade Caco-2/TC-7 cells. After treatment, L. kefir S-layer protein was detected associated with Salmonella, suggesting a protective role of this protein on association and invasion.

Implementing a post-graduate degree course for diabetes educators in Argentina. Gagliardino, Juan Jose; Malbran, Maria del Carmen; Clark, Charles One reason for poor diabetes outcomes – the development of disabling, potentially life-threatening complications – is the lack of effective participation by people with diabetes in the management of their own condition. This participation is the key to successfully achieving therapeutic goals. To be able to follow a difficult and complex life-long regimen requires high levels of motivation and knowledge. Yet although extensive evidence supports this concept, only a minority of people receive appropriate diabetes education. Thus, many people with diabetes are handicapped in their self-care by limited knowledge and skills. The authors describe an initiative in La Plata, Argentina, which aims to promote and diffuse high-quality diabetes education by training healthcare providers to become expert educators.

The diabetes-related attitudes of health care professionals and persons with diabetes in Argentina; Actitudes relacionadas con la diabetes en los profesionales sanitarios y las personas con diabetes en Argentina Gagliardino, Juan Jose; González, Claudio; Caporale, Joaquín E. To test diabetes-related attitudes of health care team members (HCTMs) and people with diabetes in a developing country, in this case, Argentina. The third version of the Diabetes Attitudes Scale (DAS-3) was randomly administered, in person, to 252 HCTMs (nurses, nutritionists, physicians, podiatrists, and social workers) and 279 people with type 1 or type 2 diabetes mellitus in several provinces of Argentina in 2004. Data from 531 completed questionnaires were included in the study. The data were statistically analyzed using analysis of variance, covariance, chi-square, and t-tests.; Analizar las actitudes relacionadas con la diabetes en los miembros del equipo de salud (MES) y las personas con diabetes en un país en desarrollo, Argentina. Se administró de forma aleatoria la tercera versión de la Escala de Actitudes en la Diabetes (DAS-3) a 252 MES (enfermeros, nutriólogos, médicos, podólogos y trabajadores sociales) y a 279 personas con diabetes mellitus tipos 1 ó 2 en varias provincias de Argentina en 2004. Los datos de 531 cuestionarios respondidos se evaluaron mediante análisis de varianza y covarianza, y las pruebas de la t y de la ji al cuadrado.