Effects of natural phenolic compounds from a desert dominant shrub Larrea divaricata Cav. on toxicity and survival in mice; Efectos de los compuestos fenólicos naturales de un arbusto dominante del desierto, Larrea divaricata Cav. sobre la toxicidad y sobrevida en ratones Ríos, Juan Manuel; Mangione, Antonio Marcelo; Gianello, Jose Carlos Los herbívoros generalistas pueden evitar la intoxicación ingiriendo pequeñas cantidades de una mezcla de metabolitos secundarios de plantas. Sin embargo, un solo compuesto, uno altamente tóxico o el más abundante en la mezcla es el que podría causar la intoxicación. La sobrevida y la toxicidad en ratones Rockland machos fueron evaluadas para determinar si los efectos tóxicos de la resina fenólica de jarilla (Larrea divaricata Cav.) se debe a su compuesto mayoritario, el ácido nordihidroguaiarético (ANDG) o a la concentración total de compuestos fenólicos en esta resina. Este objetivo fue logrado mediante la exposición de ratones a la alimentación voluntaria de alimento para rata tratado con resina y mediante el gavage oral de ratones con las siguientes dosis y compuestos: Resina-100 mg (n = 7), ANDG-15 mg (n = 8), ANDG-100 mg (n = 10) y Control (n = 6). Nuestra hipótesis fue que los efectos tóxicos de Larrea divaricata son atribuibles al ANDG solamente. La ingesta voluntaria de resina por ratones tuvo un efecto tóxico pronunciado, evidenciado en una pérdida en masa corporal y una reducción significativa de la ingesta de alimento. Ratones expuestos a gavage con Resina-100 mg, ANDG-100 mg y ANDG-15 mg mostraron una reducción significativa de la sobrevida comparada con ratones bajo las condiciones Control. Animales expuestos a ANDG-15 mg tuvieron una mayor sobrevida comparado con animales expuestos a ANDG-100 mg y una sobrevida equivalente a los animales expuestos a Resina-100 mg (que contiene a su vez 15 mg de ANDG). No se detectaron diferencias significativas en la detoxificación medida como conjugados de ácido glucurónico en orina entre los tratamientos de gavage. Dado que 15 mg de ANDG fueron suficientes para producir el mismo efecto que la resina total, sugerimos que el ANDG es el constituyente principal de la resina de Larrea divaricata responsable del efecto tóxico de esta planta.; It is known that generalist herbivores may circumvent intoxication by ingesting small quantities from a mixture of plant secondary metabolites. However a single chemical, a highly toxic one or the most abundant in the mixture could cause toxicity. Survivorship and toxicity in Rockland male mice were measured to determine if the toxic effects of the phenolic resin of creosote bush (Larrea divaricata Cav.) is due to its major constituent, the nordihydroguaiaretic acid (NDGA) or to the total concentration of phenolic compounds in this resin. This objective was accomplished by exposing mice to voluntary feeding on resin-treated rat chow and by oral gavaging of mice with the following doses and compounds: Resin-100 mg (n = 7), NDGA-15 mg (n = 8), and NDGA-100 mg (n = 10) and Control (n = 6). Our hypothesis was that NDGA is responsible for the toxicity of Larrea divaricata's phenolic resin. Voluntary resin intake by mice had a pronounced toxic effect, producing body mass loss and significant reduction of food intake. Mice gavaged with Resin-100 mg, NDGA-100 mg, and NDGA-15 mg showed a significant reduction in survival probability compared to mice under Control conditions. Animáis exposed to NDGA-15 mg had a higher survivorship compared to the NDGA-100 mg animáis, and equivalent survivorship to the Resin-100 mg (containing 15 mg of NDGA) animáis. No significant differences in detoxification, measured as glucuronic acid conjugates in urine, were detected among gavage treatments. Therefore, given that just 15 mg of NDGA were enough to produce the same effect as the whole resin, we suggest that NDGA is the main constituent of Larrea divaricata's resin responsible for the toxic effect of the phenolic resin of this plant.

Prognostic value of Bcl-2 in breast cancer patients treated with neoadjuvant anthracycline based chemotherapy Vargas Roig, Laura Maria; Cuello Carrión, Fernando Darío; Fernández-Escobar, Nicolás; Daguerre, Pedro; Leuzzi, Marcela; Ibarra, Jorge; Gago, Francisco E.; Nadin, Silvina Beatriz; Ciocca, Daniel Ramon We have analyzed the predictive/prognostic value of Bcl-2 protein in breast cancer patients treated with neoadjuvant chemotherapy. One hundred and ten patients were submitted to two different chemotherapeutic regimens: a) 5-fluorouracil, adriamycin or epirubicin, and cyclophosphamide (FAC/FEC) during 2-6 cycles before surgery and 3 or 4 additional cycles of FAC/FEC after surgery (n = 40) and b) doxorubicin (D) 75 mg/m2 or epirubicin (E) 120 mg/m2 during 4 cycles before surgery, and 6 cycles of cyclophosphamide, methotrexate, and 5-fluorouracil (CMF) after surgery (n = 70). Bcl-2 expression, evaluated by immunohistochemistry, did not change significantly after chemotherapy and was not related to clinical/pathological response. In FAC/FEC group, Bcl-2 positive expression after chemotherapy correlated with better disease free survival (DFS) and overall survival (OS) (P = 0.008 and P = 0.001). In D/E group, Bcl-2 also correlated with better DFS and OS (P = 0.03 and P = 0.054) in the post-chemotherapy biopsies. An unusual nuclear localization of Bax was observed in some biopsies, but this localization did not correlate with the tumor response or outcome of the patients. We found that a high Bcl-2 expression had no predictive value but had prognostic value in breast cancer patients treated with neoadjuvant anthracycline based chemotherapy.

Ear tufts in Ferruginous Pygmy-Owl (Glaucidium brasilianum) as alarm response Santillan, Miguel Angel; Sarasola, José Hernán; Dolsan, Marcelo

Eficiencia relativa de distintas técnicas de captura de heterópteros terrestres en un pastizal de montaña Marrero, Hugo Javier; Zalba, Sergio Martín; Carpintero, Diego Leonardo Los insectos habitan múltiples micro-ambientes y tienen nichos tróficos muy variados, razón por la cual existen diversas alternativas para su detección. En este trabajo se testeo el uso de distintas técnicas de captura de heterópteros terrestres sobre un pastizal de montaña, procurando la técnica o la combinación de técnicas que mejor representara la diversidad del grupo y que insumiera el menor esfuerzo, de manera de optimizar acciones de monitoreo. El trabajo se realizó durante las cuatro estaciones del año, sobre cuatro niveles altitudinales en la ladera del Cerro Curamalal (provincia de Buenos Aires) usando trampas de caída, red entomológica, trampa de luz y captura manual. La red entomológica resultó la técnica más eficiente, seguida por las trampas de caída, la captura manual y la trampa de luz. La combinación de captura manual y red entomológica rindieron los mejores resultados en términos de representación de la diversidad de heterópteros en el área de estudio. Se determinó además que la época de primavera-verano y los estratos intermedios de altura concentran la mayor diversidad específica del grupo.; Insects thrive in multiple micro-habitats and correspond to diverse trophic niches which is why there are multiple and diverse alternatives for their sampling. In this study we tested different techniques for capturing terrestrial heteropterans in a mountain grassland searching for the technique or combination of techniques that best represented this group´s biodiversity in the area. Sampling took place during all four seasons at four altitudinal levels on the Curamalal hill (Buenos Aires province) and we compared pit-fall traps, entomological net, light traps, and manual capture. When considering each technique separately, entomological nets rendered the best performance, followed by pit-fall traps, manual capture and light traps. The combination of entomological net and manual capture resulted in the best representation of heteropteran diversity in the study area. Spring and summer and intermediate heights on the hills concentrate the highest species diversity in this group of insects.

Deactivation studies of the SCR of NOx with hydrocarbons on Co-mordenite monolithic catalysts Boix, Alicia Viviana; Aspromonte, Soledad Guadalupe; Miro, Eduardo Ernesto The catalytic reduction of NOx with hydrocarbons (butane or methane) on CoMOR washcoated monolithic catalysts was studied in the presence of steam and excess oxygen. The significant changes observed in the catalytic behavior of CoMOR powder and monoliths depended essentially on the hydrocarbon nature (carbon number) and the concentration of water in the feed. When the reducing agent was methane, a low concentration of water (2%) decreased the NO to N2 conversion. However, when butane was used instead of methane, the maximum NOx conversions increased from 50 to 58% and from 52 to 64% for the CoMOR powder and monolith, respectively. The presence of water inhibited the NO adsorption when the reducing agent was methane but when butane was used, water helped to remove the surface-carbon deposits as indicated by TPO and XPS results. This fact explains the increase observed in the NOx conversion. The characterization with TPR and UV-vis spectroscopy showed that the main Co species present in the selective catalysts were the Co(II) ions exchanged at different sites of the mordenite and highly dispersed CoxOy moieties. More rigorous reaction conditions, i.e. 10% of water, led to the irreversible deactivation with both reductants. The Co3O4 phase was detected in all the deactivated powder and monolithic catalysts. The Co3O4 spinel was formed from the cobalt ion migration, which was promoted in wet atmosphere. In addition, for monolithic catalysts washcoated with CoMOR, the silica binder inhibited the water deactivation effect probably due to the silica-cobalt interaction, as a CoxOySi silicate.

The ATLAS Experiment at the CERN Large Hadron Collider Piegaia, Ricardo Nestor; Aad, G.; Romeo, G.; Sanchis Lozano, M.A; Miyagawa, P.S.; Antonelli, S.; Bendel, M.; Breiler, B.; Castrovillari, F.; Civera, J.V.; Del Prete, T.; Duffin, S.; Fichet, S.; Gaumer, O.; Goodrick, M. J.; Goujdami, D.; Herten, G.; Jeremie, A; Kieft, G.; König, S.; Kirk, J.; Lapin, V.V.; LeGeyt, B.C.; Love, J.; Merola,L.; Raith, B.; Plamondon, M.; Saavedra, A.F.; Schott, M.; Soloviev, I. The ATLAS detector as installed in its experimental cavern at point 1 at CERN is described in this paper. A brief overview of the expected performance of the detector when the Large Hadron Collider begins operation is also presented.

Emulsion Polymerization of Styrene with iso-octyl-3-mercaptopropionate as Chain Transfer Agent Minari, Roque Javier; Vega, Jorge Ruben; Gonzalez Sierra, Manuel; Meira, Gregorio Raul; Gugliotta, Luis Marcelino Four batch and unseeded emulsion polymerizations of styrene were investigated, which included isooctyl 3-mercaptopropionate (iOMP) as chain transfer agent (CTA). This compound was analyzed by 13C NMR and GC/ MS, resulting in a mixture of over 10 isomers. Because of different reactivities of the CTA isomers, the produced polystyrenes presented broad and bimodal molecular weight distributions (MWDs). A mathematical model was adjusted to the measurements, and the measured MWDs were adequately predicted when assuming the CTA as a binary mixture of high but different reactivities.

Universidad, interculturalidad y discurso público: La universidad en un contexto social democrático; University, interculturality and public discourse: The university in a social-democratic context; Université, interculturalité et discours public: L’universite dans un contexte social-démocratique Michelini, Dorando Juan La universidad constituye el lugar privilegiado de la sociedad civil en el que los ciudadanos buscan nuevos conocimientos y se preparan para participar como expertos en la tematización, discusión y resolución de todas aquellas cuestiones teóricas y prácticas relevantes para la sociedad. La educación universitaria tiene que contribuir, por consiguiente, a la formación de docentes e investigadores, tecnólogos y expertos en las diversas esferas del saber, y a la capacitación para la reflexión crítica a través del desarrollo de competencias discursivas, éticas y culturales. En este sentido, los universitarios son -tendrían que ser- personas capacitadas no sólo para aumentar metódica y sistemáticamente el conocimiento, sino también para reflexionar críticamente sobre cuestiones centrales de la convivencia humana en un sistema democrático. Por ello, los universitarios tendrían que ser profesionales y expertos, a la vez que “personas de principios”, conocedoras de su propia cultura y del contexto histórico de aplicación.; The university constitutes the privileged place of civil society in which citizens seek new knowledge and prepare themselves to participate as experts in the discussion and resolution of all theoretical and practical issues relevant to society. University education has to contribute, therefore, to the formation of teachers and researchers, technologists and experts in the diverse spheres of knowledge, and to the training for critical thinking through the development of ethical, cultural and discursive skills. In this regard, university graduates are - should be- people qualified not only to enlarge their knowledge methodically and systematically, but also to reflect critically on central questions of human coexistence in a democratic system. Thus, university graduates would have to be professionals and experts as well as "people of principles", proficient in their own culture and in the historical context of implementation.; L’Université constitue l’endroit privilégié de la société civile où les citoyens cherchent de nouvelles connaissances et se préparent pour participer en tant qu’experts, à la thématisation, la discussion et la résolution de toutes les questions théoriques et pratiques remarquables pour la société. En conséquence, l’éducation universitaire doit contribuer à la formation d´enseignants et de chercheurs, de technologues et d’experts dans les diverses sphères du savoir et à la préparation à la réflexion critique à travers le développement de compétences discursives, éthiques et culturelles. Dans ce sens, les universitaires sont –devraient être- des personnes prêtes, non seulement à accroître méthodiquement et systématiquement la connaissance mais aussi à réfléchir de manière critique sur les questions centrales de la vie en commun dans un système démocratique. Les universitaires devraient être des professionnels et des experts, mais en même temps des «gens de principes», connaisseurs de leur propre culture et du contexte historique d’application.

Factors affecting the use of 13Cα chemical shifts to determine, refine, and validate protein structures Vila, Jorge Alberto; Scheraga, Harold A. Interest centers here on the analysis of two different, but related, phenomena that affect side-chain conformations and consequently 13Cα chemical shifts and their applications to determine, refine, and validate protein structures. The first is whether 13Cα chemical shifts, computed at the DFT level of approximation with charged residues is a better approximation of observed 13Cα chemical shifts than those computed with neutral residues for proteins in solution. Accurate computation of 13Cα chemical shifts requires a proper representation of the charges, which might not take on integral values. For this analysis, the charges for 139 conformations of the protein ubiquitin were determined by explicit consideration of protein binding equilibria, at a given pH, that is, by exploring the 2ξ possible ionization states of the whole molecule, with ξ being the number of ionizable groups. The results of this analysis, as revealed by the shielding/deshielding of the 13Cα nucleus, indicated that: (i) there is a significant difference in the computed 13Cα chemical shifts, between basic and acidic groups, as a function of the degree of charge of the side chain; (ii) this difference is attributed to the distance between the ionizable groups and the 13Cα nucleus, which is shorter for the acidic Asp and Glu groups as compared with that for the basic Lys and Arg groups; and (iii) the use of neutral, rather than charged, basic and acidic groups is a better approximation of the observed 13Cα chemical shifts of a protein in solution. The second is how side-chain flexibility influences computed 13Cα chemical shifts in an additional set of ubiquitin conformations, in which the side chains are generated from an NMR-derived structure with the backbone conformation assumed to be fixed. The 13Cα chemical shift of a given amino acid residue in a protein is determined, mainly, by its own backbone and side-chain torsional angles, independent of the neighboring residues; the conformation of a given residue itself, however, depends on the environment of this residue and, hence, on the whole protein structure. As a consequence, this analysis reveals the role and impact of an accurate side-chain computation in the determination and refinement of protein conformation. The results of this analysis are: (i) a lower error between computed and observed 13Cα chemical shifts (by up to 3.7 ppm), was found for ∼68% and ∼63% of all ionizable residues and all non-Ala/Pro/Gly residues, respectively, in the additional set of conformations, compared with results for the model from which the set was derived; and (ii) all the additional conformations exhibit a lower root-mean-square-deviation (1.97 ppm ≤ rmsd ≤ 2.13 ppm), between computed and observed 13Cα chemical shifts, than the rmsd (2.32 ppm) computed for the starting conformation from which this additional set was derived. As a validation test, an analysis of the additional set of ubiquitin conformations, comparing computed and observed values of both 13Cα chemical shifts and χ1 torsional angles (given by the vicinal coupling constants, 3JN−Cγ and 3JC′−Cγ, is discussed.

Anatomía foliar de Rauvolfia schuelii Speg. (Apocynaceae), en la provincia de Tucumán (Argentina); Leaf anatomy of Rauvolfia schuelii (Apocynaceae), in the Tucumán province, Argentina Debes, Mario Alberto; Luque, Ana Catalina; Arias, Marta Eugenia; Albornoz, Patricia Liliana Mario Alberto Debes, Ana Catalina Luque, Marta Eugenia Arias, Patricia Liliana Albornoz. 2008. “Anatomía foliar de Rauvolfia schuelii (Apocynaceae), en la provincia de Tucumán, Argentina”. Lilloa 45 (1-2). Rauvolfia schuelii Speg. es un arbusto o arbolito de 2-6 m de altura, se distribuye en el noroeste de Argentina, entre los 450-1500 m snm. El objetivo del presente trabajo fue estudiar la anatomía foliar de Rauvolfia schuelii Speg. en la provincia de Tucumán. Se utilizó material fresco y fijado en FAA; se realizaron diafanizados, cortes transversales y longitudinales de lámina y pecíolo mediante técnicas anatómicas convencionales. Los resultados muestran que la hoja es dorsiventral, hipostomática, con cutícula estriada. Se presentan diferentes tipos de estomas: hemiparacítico, paracítico, anisocítico, tetracítico, ciclocítico y actinocítico. El pecíolo en sección transversal es subcircular con coléteres en la base. Las drusas y los haces vasculares bicolaterales se presentan en lámina y pecíolo. Los tubos latifíceros son articulados ramificados y no articulados en toda la lámina. Estos caracteres anatómicos son válidos para la correcta identificación de esta especie.; Rauvolfia schuelii Speg. is a shrub or tree about 2-6 m high. In the northwestern of Argentina it grows between 450-1500 m snm. The aim of this work was to study the leaf anatomy of Rauvolfia schuelii in Tucumán. Conventional anatomical techniques were applied. The leaf is dorsiventral and hypostomatic. There are six types of sto- mata: hemiparacytic, paracytic, anisocytic, tetracytic, cyclocytic and actinocytic. The petiole in transversal section is subcircular with colleters at the base. Druses, colateral vascular bundle and laticiferous tubes in laef and petiole are observed. Results show that leaf anatomical features permit to identify these species.

Coordination of leaf and stem water transport properties in tropical forest trees Meinzer, Frederick C.; Woodruff, David R.; Domec, Jean-Christophe; Goldstein, Guillermo Hernan; Campanello, Paula Inés; Gatti, Maria Genoveva; Villalobos-Vega, Randol Stomatal regulation of transpiration constrains leaf water potential (ΨL) within species-specific ranges that presumably avoid excessive tension and embolism in the stem xylem upstream. However, the hydraulic resistance of leaves can be highly variable over short time scales, uncoupling tension in the xylem of leaves from that in the stems to which they are attached. We evaluated a suite of leaf and stem functional traits governing water relations in individuals of 11 lowland tropical forest tree species to determine the manner in which the traits were coordinated with stem xylem vulnerability to embolism. Stomatal regulation of ΨL was associated with minimum values of water potential in branches (Ψbr) whose functional significance was similar across species. Minimum values of Ψbr coincided with the bulk sapwood tissue osmotic potential at zero turgor derived from pressure-volume curves and with the transition from a linear to exponential increase in xylem embolism with increasing sapwood water deficits. Branch xylem pressure corresponding to 50% loss of hydraulic conductivity (P 50) declined linearly with daily minimum Ψbr in a manner that caused the difference between Ψbr and P 50 to increase from 0.4 MPa in the species with the least negative Ψbr to 1.2 MPa in the species with the most negative Ψbr. Both branch P 50 and minimum Ψbr increased linearly with sapwood capacitance (C) such that the difference between Ψbr and P 50, an estimate of the safety margin for avoiding runaway embolism, decreased with increasing sapwood C. The results implied a trade-off between maximizing water transport and minimizing the risk of xylem embolism, suggesting a prominent role for the buffering effect of C in preserving the integrity of xylem water transport. At the whole-tree level, discharge and recharge of internal C appeared to generate variations in apparent leaf-specific conductance to which stomata respond dynamically.

From synapses to behavior: development of a sensory-motor circuit in the leech Marin Burgin, Antonia; Kristan, William B.; French, Kathleen A. The development of neuronal circuits has been advanced greatly by the use of imaging techniques that reveal the activity of neurons during the period when they are constructing synapses and forming circuits. This review focuses on experiments performed in leech embryos to characterize the development of a neuronal circuit that produces a simple segmental behavior called "local bending." The experiments combined electrophysiology, anatomy, and FRET-based voltage-sensitive dyes (VSDs). The VSDs offered two major advantages in these experiments: they allowed us to record simultaneously the activity of many neurons, and unlike other imaging techniques, they revealed inhibition as well as excitation. The results indicated that connections within the circuit are formed in a predictable sequence: initially neurons in the circuit are connected by electrical synapses, forming a network that itself generates an embryonic behavior and prefigures the adult circuit; later chemical synapses, including inhibitory connections, appear, "sculpting" the circuit to generate a different, mature behavior. In this developmental process, some of the electrical connections are completely replaced by chemical synapses, others are maintained into adulthood, and still others persist and share their targets with chemical synaptic connections.

Algunas notas para pensar la participación infantil Llobet, Valeria Silvana El marco normativo internacional de derechos humanos es un conjunto interrelacionado e interdependiente de derechos, donde la Convención de Derechos del Niño (CDN) representa un avance en el sentido de la especificación por ciclo vital de los derechos a aquellos grupos etáreos más vulnerables. El acuerdo internacional, en este terreno, hace de los cuatro principios de la CDN (supervivencia y desarrollo, interés superior del niño, no discriminación, participación) los ejes para la acción respecto de la infancia. La participación infantil es sancionada en el artículo 12, y convocada en todas aquellas instancias que involucren el interés de niños, niñas y adolescentes. Los límites que su definición aporta a la implementación han sido materia de debates y reflexiones. El problema de la participación infantil, más allá o más acá de su expresión jurídica en la Convención de Derechos del Niño, remite a la concepción de democracia y ciudadanía que, como sociedad, nos damos. En efecto, concebir a la democracia como confinada a su expresión política institucional, y considerar que la ciudadanía es la titularidad y el conocimiento de derechos y obligaciones sancionados, otorga legitimidad a la participación infantil entendida como el ejercicio temprano de las virtudes cívicas propias de la vida adulta, acorde con las capacidades propias del momento vital del niño/a. ¿Es posible interpretarlo de otra manera? ¿Qué aporta, si algo, considerar a la democracia, a la ciudadanía y a la participación infantil en un sentido más amplio que el mencionado?

A new genus and two new species of Tingidae (Heteroptera) from Central America Montemayor Borsinger, Sara Itzel A new genus, Ceratotingis, distributed in Central America, is described to accommodate two new species, C. rafaeli from Panama and C. costarriquense from Costa Rica and to include Macrotingis zeteki from Panama. This paper includes descriptions of the new genus and its species, a redescription of C. zeteki, an identification key, and habitus photographs.

Caracterización fenotípica y genotípica de la resistencia a imipenem en Pseudomonas aeruginosa aisladas en un hospital de Buenos Aires; Phenotypic and genotypic characterization of imipenem-resistant Pseudomonas aeruginosa isolated in Buenos Aires Cejas, Daniela; Almuzara, Marisa; Santella, Gisela Natalia; Tuduri, A.; Palombarani, Susana; Figueroa, S.; Gutkind, Gabriel Osvaldo; Radice, Marcela Alejandra En el presente estudio, que tuvo por objeto analizar los mecanismos involucrados en la resistencia a carbapenemes, se incluyeron 129 aislamientos de Pseudomonas aeruginosa recuperados durante el año 2006 en el Hospital “Eva Perón” de la Provincia de Buenos Aires. La caracterización fenotípica y genotípica de la resistencia permitió reconocer la presencia de metalo-β-lactamasas (MBL) en el 14% de esos aislamientos. En todos ellos se identificó la presencia de la enzima IMP-13; sin embargo, algunos aislamientos resultaron sensibles a carbapenemes de acuerdo con los puntos de corte establecidos por el CLSI e incluso con las sugerencias de la Subcomisión de Antimicrobianos de SADEBAC, AAM. El ensayo de detección fenotípica de MBL de sinergia con doble disco resultó útil en este estudio. Sólo aquellos aislamientos productores de IMP-13 que a su vez presentaron alteraciones en las proteínas de membrana externa resultaron completamente resistentes a imipenem. Los aislamientos productores de MBL correspondieron a varios tipos clonales, lo cual sugiere no sólo la diseminación de una cepa resistente, sino también la diseminación horizontal de este mecanismo de resistencia entre clones diferentes.; From 129 P. aeruginosa isolated at a health care centre located in Buenos Aires (Hospital “Eva Perón”), 14% produced IMP-13. Although 18 isolates were metallo-β-lactamases (MBL) producers, only those isolates that displayed altered outer membrane protein profiles correlated with the resistant category according to CLSI or even Subcomisión de Antimicrobianos, SADEBAC, AAM. Phenotypic screening of metallo-β-lactamases proved to be appropriate for detecting MBL producing isolates. IMP-13 producing isolates corresponded to at least five different clonal types, which not only suggests the dissemination of the resistant strain but also of the resistant marker.

Impacto del alumbrado público en la atracción de insectos en áreas subtropicales Mattivi, María de Los Rosarios; Cabello, Alberto José; Kirschbaum, Carlos Federico Este trabajo es una extensión, en cuanto a resultados se refiere, del artículo publicado en la Revista Luminotecnia nº83 “El Alumbrado Público y la Polución Lumínica en un Poblado Rural”. A partir de experimentos en desarrollo, se infiere el impacto ambiental de la Polución Lumínica por parte del Alumbrado Público en la población de insectos en ciudades y zonas rurales situadas en una región de clima subtropical. Se busca cuantificar los efectos en la atracción de insectos por parte de los distintos tipos de lámparas de uso frecuente en alumbrado Público.

Parasites of the Brazilian sandperch Pinguipes brasilianus Cuvier: A tool for stock discrimination in the Argentine Sea Timi, Juan Tomas; Lanfranchi, Ana Laura; Etchegoin, Jorge Alejandro; Cremonte, Florencia The use of parasites as biological tags allowed the identification of three stocks of Brazilian sandperch Pinguipes brasilianus in the Argentine Sea. A total of 156 specimens caught during spring 2006, off the coasts of Buenos Aires Province (38°27′ S; 57°90′ W, n = 54), San Matías Gulf (42°S; 65°10′ W, n = 52) and Nuevo Gulf (42°09′ S; 64°05′ W, n = 50), were examined for parasites and 21 species were found, including monogeneans, digeneans, cestodes, nematodes, acanthocephalans and crustaceans. Diet analyses showed that Brazilian sandperch feed mainly on benthic macroinvertebrates, with differences in relative importance of main items between zones. Univariate analysis on parasite population descriptors, as well as a discriminant analysis, allowed the identification of discrete stocks in each zone, although a higher degree of similarity was observed between both Patagonian Gulfs. Northern samples were characterized by higher values of prevalence and abundance of Grillotia sp., Corynosoma australe and Scolex polymorphus. On the other hand, Trifur tortuosus and Opecoelidae gen. sp. were important in determining the position of Patagonian samples and were specially related to those from Nuevo Gulf, whereas none of the species was clearly related only to fish from San Matías Gulf. The size of the hosts is likely to influence the similarity among zones, with larger fish as better tools to discriminate stocks, probably because they harbour 'mature' assemblages shaped longer by differential environmental conditions and diet in each zone. Parasite species characteristic of sandperch from Buenos Aires Province, which display very low specificity among fish species in this area, have been previously identified as biological tags for other host species in these region, confirming their value as tags for stock delineation.

Palaeosalinity variations in the Early Cretaceous of the Neuquén Basin, Argentina: Evidence from oxygen isotopes and palaeoecological analysis Lazo, Dario Gustavo; Aguirre-Urreta, Maria Beatriz; Price, Gregory D.; Rawson, Peter F.; Ruffell, Alastair H.; Ogle, N. The Neuquén Basin is a stratigraphically- and economically-important Early Cretaceous depocentre located in west-central Argentina. The Early Valanginian to Early Barremian succession (upper Vaca Muerta, Mulichinco and Agrio Formations) contains a rich fossil record, with abundant bivalves and ammonoids. Palaeosalinities are determined systematically throughout the succession, based on an oxygen isotope analysis of unaltered oyster shells from two localities in Neuquén province. A total of 188 oyster samples from 52 stratigraphic levels were processed. A total of 52 mean values of δ18O isotope are used to calculate palaeosalinities, assuming an estimated water temperature of 25 °C. The observed range of palaeosalinities, between the maximum and the minimum, is 19, which is in conflict with published accounts of this being a fully marine succession. The isotopic data are combined with independent faunal evidence to evaluate palaeosalinity variation both laterally and temporally. Significant fluctuations in water salinity are indicated, with a clear tendency to increase from brachyhaline to euhaline and near hyperhaline conditions through time. The fluctuations were probably due to dilution from normal marine water, caused primarily by variations in rainfall and continental runoff. In addition, the presence of a volcanic island arc along the western margin of the basin may have at least partially isolated the basin from the marine waters of the Pacific Ocean. Also, a gulf-shaped basin may have inhibited hydrodynamic exchange with the ocean while enhancing retention of continental waters.

Determination of Size Distributions of Concentrated Polymer Particles Embedded in a Solid Polymer Matrix Soulé, Ezequiel Rodolfo; Elicabe, Guillermo Enrique In this work we present the results obtained from the size characterization of polymer particles embedded in a solid polymer matrix using Static Light Scattering (SLS) and Scanning Electron Microscopy (SEM). The analyzed samples are the result of the solution polymerization of isobornyl methacrylate (IBoMA) in polyisobutylene (PIB) at complete conversion. Induced by polymerization, the system undergoes phase separation. As a result, spherical micron sized particles rich in PIB are formed. At the end of the polymerization, the particles become trapped in a solid polymer matrix rich in Poly‐IBoMA. Size, concentration, and refractive index, make the resulting particle system scatter light under the Rayleigh‐Debye‐Gans (RDG) regime with interparticle interference. For Light Scattering (LS) characterization the samples are measured with a Flat Cell Static Light Scattering (FCSLS) apparatus, in which the reaction takes place. The resulting SLS spectra are analyzed using the Percus‐Yevick approximation to model the interference effects. The local monodisperse approximation is used to consider polydispersity in the particle sizes. The estimated particle size distributions agree well with the measurements from SEM. In this work a concentrated particle system that naturally scatters light according to the RDG regime has been fully characterized in terms of its particle size distribution. This work, against the opinion of other authors, shows the feasibility of measuring still particles using a one dimensional array of light detectors.

Controlling the N - And S -representability of the second-order reduced density matrix: The doublet-state case Alcoba, Diego Ricardo; Valdemoro, C; Tel, L. M.; Perez Romero, E. A purification procedure that simultaneously corrects the N - and S -representability main defects of a second-order reduced density matrix (2RDM), second-order hole reduced density matrix (2HRDM), and second-order G matrix is presented here. In this purifying procedure, the generalized unitarily invariant second-order matrix decomposition for the 2RDM and the 2HRDM as well as for the G matrix is combined with the S -representability conditions. In particular, here we will focus our attention on the RDMs corresponding to doublet states. We will thus explicitly give the S -representability conditions that a two-body correlation matrix has to satisfy when an N -electron system is in a doublet spin-state in the spin-component of maximum projection. Furthermore, as a consequence of the G -matrix spin properties (which directly affect the S -representability of the 2RDM), we show that a different contracting form for the 2RDM is possible. The numerical results presented in this work confirm the efficiency of our purifying procedure. © 2008 The American Physical Society.