Modeling natural photic entrainment in a subterranean rodent (Ctenomys aff. knighti), the tuco-tuco Flôres, Danilo E. F. L.; Tomotani, Barbara M.; Tachinardi, Patricia; Oda, Gisele Akemi; Valentinuzzi, Verónica Sandra Subterranean rodents spend most of the day inside underground tunnels, where there is little daily change in environmental variables. Our observations of tuco-tucos (Ctenomys aff. knighti) in a field enclosure indicated that these animals perceive the aboveground light-dark cycle by several bouts of light-exposure at irregular times during the light hours of the day. To assess whether such light-dark pattern acts as an entraining agent of the circadian clock, we first constructed in laboratory the Phase Response Curve for 1 h light-pulses (1000lux). Its shape is qualitatively similar to other curves reported in the literature and to our knowledge it is the first Phase Response Curve of a subterranean rodent. Computer simulations were performed with a non-linear limit-cycle oscillator subjected to a simple model of the light regimen experienced by tuco-tucos. Results showed that synchronization is achieved even by a simple regimen of a single daily light pulse scattered uniformly along the light hours of the day. Natural entrainment studies benefit from integrated laboratory, field and computational approaches.

Low-Dimensional magnetic systems in nanopore arrays Bajales Luna, Noelia; Viqueira, María Soledad; Avalle, Lucia Bernardita; Urreta, Silvia Elena; Bercoff, Paula Gabriela FeCo nanowires 20 nm diameter are synthesized by AC electrodeposition using AAO membranes as templates. The hysteresis and structural properties of the as deposited nanowire arrays are characterized. The orientation dependence of the coercive field measured in the array is compared with the predictions of a magnetization reversal model involving the nucleation and propagation of a transverse wall. The model is promissory because it predicts the experimental curve shape quite well.

Hysteresis properties of hexagonal arrays of FePd nanowires Viqueira, María Soledad; García, Sebastián Eduardo; Urreta, Silvia Elena; Pozo Lopez, Gabriela del Valle; Fabietti, Luis Maria Rodolfo FePd nanowires (NWs) with different compositions have been grown into anodized aluminum oxide templates (AAO) by AC electrodeposition at room temperature. The effects of nanowire composition and morphology on the hysteresis properties of the ordered array of NWs are investigated. All the NWs are polycrystalline; the Fe-rich wires have a bcc structure while the Pd rich ones are fcc. FePd NWs are ferromagnetic and the spontaneous magnetization is found to be parallel to the nanowire long axis (out of plane easy axis) and both, the saturation polarization and the coercive field increase with the iron content.

Historia/Histoire(s). Las imágenes de Walter Benjamin y Jean-Luc Godard; Histories/Histoire(s). Images of Walter Benjamin and Jean-Luc Godard Taccetta, Natalia Roberta A partir de Histoire(s) du cinéma de Jean-Luc Godard, se intenta revisar algunas nociones fundamentales de la filosofía de la historia de Walter Benjamin. Esto implica volver sobre la importancia del montaje como mecánica historiadora y sobre el modo en que la re-escritura de la historia posibilita miradas políticamente informadas más acordes con la “historia a contrapelo” benjaminiana. En este sentido, se vuelve ineludible la noción de “ruina” que permite volver sobre la mirada heterodoxa de Benjamin, opuesta a los sentidos históricos únicos y la racionalización teleológica de los acontecimientos.; Taking as our starting point Jean-Luc Godard´s film Histoire(s) du cinéma, we intend to review some basic concepts of Walter Benjamin’s philosophy of history. This implies the return to montage as a historic procedure and also to the way in which the re-writing of history enables new political views according to the benjaminian notion of “history against the grain”. In this sense, it becomes unavoidable the notion of “ruin” that allows an unorthodox look at History, different from those which propose a single historical meaning or the teleological rationalization of events.

Export emergence of differentiated goods from developing countries: Export pioneers and business practices in Argentina Artopoulos, Alejandro; Friel, Daniel; Hallak, Juan Carlos This study explores the underlying factors that enable firms from developing countries to successfully export differentiated goods to developed countries. The article describes four case studies of export emergence in differentiated-good sectors in Argentina, namely wine, television programs, motorboats, and wooden furniture. The case studies rely primarily on an extensive set of interviews. We find that consistent exporters to developed countries adopt a new set of business practices that differ starkly from those that prevail in their domestic market. In three of the sectors, an export pioneer led the adoption of these new practices. Export pioneers possessed tacit knowledge about foreign markets, achieved through their previous embeddedness in the business community of those markets. Export emergence occurs as business practices diffuse throughout the sector. These findings point to the importance of foreign market knowledge, relative to production knowledge, as the key constraint to achieve consistent export to developed countries.

Historiografía y educación peronista: un estado de la cuestión sobre historia de la educación durante el primer peronismo Perrupato, Sebastian Domingo El presente artículo tiene por objetivo indagar y analizar la producción historiográfica sobre la educación durante el primer peronismo. Entendemos que la misma ha sido el resultado de la reapertura democrática y que su producción resulta aún hoy una cantera abierta de recursos y documentos historiográficos que esperan ser explorados y analizados por generaciones futuras.; This article aims to investigate and analyze the historiographical production about education during the first Peronist. We understand that it has been the result of the return to democracy and that their production is still today an open quarry historiographical resources and documents waiting to be explored and analyzed by future generations.

Sistema de planificación paciente-específico para medicina nuclear; Patient-specific planning system for nuclear medicine Pérez, Pedro Antonio; Malano, Francisco Mauricio; Valente, Mauro Andres Diferentes radionucleídos han demostrado ser apropiados para radioinmunoterapia (RI). La performance dosimétrica de cada radionucleído debe ser cuidadosamente estudiada y caracterizada antes del tratamiento. Estos estudios pueden ayudar tanto a optimizar el daño al tumor a irradiar, como a minimizar la probabilidad de complicaciones en los órganos sensibles cercanos al mismo. Debido a esto, es de gran interés introducir imágenes paciente-específicas durante la planificación y el proceso de cálculo para mejorar y optimizar la performance dosimétrica. En este sentido, tanto la actividad metabólica/funcional del tumor como la anatomía del paciente,deben ser incorporadas. Las técnicas de imaging metabólico han mostrado ser metodologías valiosas de diagnóstico no invasivas. Además, la tomografía computada por rayos-X puede ser usada para generar imágenes 3D con información de las estructuras anatómicas. En la actualidad, las técnicas de imaging dual como el PETCT o el SPECT-CT son capaces de combinar tanto los métodos de imaging funcional como anatómico, incluso alcanzando un matching preciso entre ellos.; Different radionuclides have proved to be appropriated for radioimmunotherapy. Dosimetric performance of each radionuclide has to be carefully studied and characterized before any treatment. These studies can help to optimize both the damage to the tumor to be irradiated and minimize the probability of complications in sensitive organs close to the tumor. It would be desirable to introduce patient specific images during the planning and calculations process in order to improve and optimize dosimetric performance. In this sense, both the tumor activity and the patient anatomy should be incorporated. Metabolic imaging techniques have shown to be valuable non-invasive and reliable diagnostic methodologies. Besides, X-Ray computed tomography can be used to generate 3D-images with information about patient anatomical structures. Nowadays, dual imaging techniques like PET-CT or SPECT-CT are capable to suitably combine both functional and anatomical imaging methods even assessing accurate matching between them.

Intenciones y artefactos: sobre el enfoque hilpineano de autoría en el ámbito de los objetos técnicos Parente, Diego Carlos El presente trabajo tiene como objetivo fundamental discutir críticamente algunas de la tesis principales del planteo hilpineano sobre los artefactos técnicos y establecer las limitaciones inherentes a su modelo de autoría. Con este propósito se reconstruyen, en primer término, los conceptos vertebradores de la posición de Hilpinen para luego indagar sus supuestos a través de un análisis de su aplicación al campo de producción contemporánea y al territorio de los bioartefactos.

Debatiendo lo rural y la ruralidad: un aporte desde el sudeste de la provincia de Buenos Aires; el caso del partido de Tres Arroyos; Debatendo o rural e a ruralidade: uma contribuição do sudeste da província de Buenos Aires; o caso do partido de Tres Arroyos; Discussing the Rural and Rurality: A Contribution from the Southeast of the Province of Buenos Aires; The Case of the Division of Tres Arroyos Mikkelsen, Claudia Andrea El objetivo del artículo consiste en discutir la presencia de una ruralidad complementaria a partir del caso del partido de Tres Arroyos, ubicado en el sudeste de la provincia de Buenos Aires (Argentina). Este análisis se hace en el marco de la “agricultura científica”, que implica, en cuanto a los lugares, la puesta en marcha de mecanismos que se ajusten a las potencialidades y especificidades de cada recorte territorial. Metodológicamente, fue central la lectura de literatura especializada, la revisión de documentos históricos, estadísticos y fotográficos, la sistematización y análisis de datos provenientes de censos de población y de censos agropecuarios, así como también la observación directa. Puede decirse que el espacio rural es testigo de profundos cambios y, a la vez, objeto de nuevas vocaciones.; O objetivo do artigo consiste em discutir a presença de uma ruralidade complementária a partir do caso do partido de Tres Arroyos, localizado no sudeste da província de Buenos Aires (Argentina). Esta análise é feita no âmbito da “agricultura científica”, que implica, em relação aos lugares, a implementação de mecanismos que se ajustem às potencialidades e especificidades de cada recorte territorial. Metodologicamente, foi fundamental a leitura de literatura especializada, a revisão de documentos históricos, estatísticos e fotográficos, a sistematização e análise de dados provenientes de censos de população e de censos agropecuários, assim como também a observação direta. Pode-se dizer que o espaço rural é testemunha de profundas mudanças e, por sua vez, de novas vocações.; The aim of the article is to discuss the existence of complementary form of rurality on the basis of the case of Tres Arroyos, located to the southeast of the province of Buenos Aires, Argentina. The analysis is framed within the field of “scientific agriculture”, which involves the implementation of mechanisms adjusted to the potential and specificities of each territory. The methodology included a review of the specialized literature, as well as of historical, statistical, and photographic photographs, and the systematization and analysis of data gathered from population and agricultural censuses and direct observation. It is possible to conclude that rural areas are experiencing profound changes and shifting toward new uses.

A molecular biology and phase II trial of lapatinib in children with refractory CNS malignancies: a pediatric brain tumor consortium study. Fouladi, Maryam; Stewart, Clinton F.; Blaney, Susan M.; Onar Thomas, Arzu; Schaiquevich, Paula Susana; Packer, Roger J.; Goldman, Stewart; Geyer, J. Rusell; Gajjar, Amar; Kun, Larry E.; Boyett, James M.; Gilbertson, Richard J. High expression of ERBB2 has been reported in medulloblastoma and ependymoma; EGFR is amplified and over-expressed in brainstem glioma suggesting these proteins as potential therapeutic targets. We conducted a molecular biology (MB) and phase II study to estimate inhibition of tumor ERBB signaling and sustained responses by lapatinib in children with recurrent CNS malignancies. In the MB study, patients with recurrent medulloblastoma, ependymoma, and high-grade glioma (HGG) undergoing resection were stratified and randomized to pre-resection treatment with lapatinib 900 mg/m(2) dose bid for 7-14 days or no treatment. Western blot analysis of ERBB expression and pathway activity in fresh tumor obtained at surgery estimated ERBB receptor signaling inhibition in vivo. Drug concentration was simultaneously assessed in tumor and plasma. In the phase II study, patients, stratified by histology, received lapatinib continuously, to assess sustained response. Eight patients, on the MB trial (four medulloblastomas, four ependymomas), received a median of two courses (range 1-6+). No intratumoral target inhibition by lapatinib was noted in any patient. Tumor-to-plasma ratios of lapatinib were 10-20 %. In the 34 patients (14 MB, 10 HGG, 10 ependymoma) in the phase II study, lapatinib was well-tolerated at 900 mg/m(2) dose bid. The median number of courses in the phase II trial was two (range 1-12). Seven patients (three medulloblastoma, four ependymoma) remained on therapy for at least four courses range (4-26). Lapatinib was well-tolerated in children with recurrent or CNS malignancies, but did not inhibit target in tumor and had little single agent activity.

Molecular and serological characterization of species B2 adenovirus strains isolated from children hospitalized with acute respiratory disease in Buenos Aires, Argentina Kajon, Adriana E.; Jong, Jan C. de; Dickson, Laura; Arron, Georgina; Murtagh, Patricia; Viale, Diana; Carballal, Guadalupe; Echavarría, Marcela Silvia BACKGROUND: Between September 2000 and November 2005, approximately 10% of the retrospectively examined human adenovirus (HAdV)-positive pediatric cases of acute respiratory disease (ARD) requiring hospitalization at the Hospital Nacional de Pediatria Juan P. Garrahan in Buenos Aires, Argentina, were found to have a HAdV-B2 infection. OBJECTIVE: To characterize genetically and antigenically the HAdV-B2 virus isolates. STUDY DESIGN: Restriction enzyme analysis (REA), hexon and fiber gene sequencing and virus neutralization assays (VN) were carried out on 8 HAdV-B2 respiratory virus isolates. RESULTS: REA showed that the 8 examined HAdV-B2 virus isolates were HAdV11, belonging to two genomic variants: HAdV11a and a BclI variant of HAdV11c which we designated 11c4. Molecular analysis of the hexon genes showed that both REA variants had a HAdV11-like hexon gene. Confirming previous reports, the 7 HAdV11a virus isolates were found to have HAdV14-like fiber genes and therefore are HAdV H11/F14. The fiber gene of the HAdV11c4 virus isolates most closely resembled that of various strains of HAdV7. In VN assays, the 4 tested HAdV11a strains were serotyped as HAdV11-14. The HAdV11c4 strain was serotyped as HAdV11 but also showed a weak but significant reactivity with antiserum to HAdV7. Compared with the other HAdV-positive cases in our study, infection with HAdV11 caused a similarly severe disease. CONCLUSIONS: Our results provide evidence to the long term world-wide circulation of HAdV H11/F14 as a causative agent of ARD. Combined, our molecular and serology data support the rationale to base the molecular typing and designation of recombinant viruses on the sequences of the hexon and fiber genes.

Análisis y distribución espacial de la vulnerabilidad social en la provincia de Salta, Argentina; Analysis and spatial distribution of social vulnerability in the province of Salta, Argentina Abeldaño Zuñiga, Roberto Ariel; Estario, Juan Carlos; Fernandez, Alicia Ruth A lo largo de su historia, la provincia de Salta ha sido afectada por distintos tipos de desastres, siendo aquellos de origen hidrometeorológico los más predominantes. Se acepta que para que se produzca una situación de desastre, una amenaza debe operar sobre una comunidad en situación de vulnerabilidad, esto es el grado de exposición de una familia o una comunidad, dada la probabilidad de ocurrencia de un peligro potencialmente dañino, y la insuficiencia o incapacidad de protegerse. Se realizó un análisis descriptivo de la base de datos correspondiente a los datos de la provincia de Salta del Censo Nacional de Población y Vivienda del año 2001, procesados a través de Redatam + SP Process. Se construyeron índices de acuerdo a la metodología empleada por Melina Con, a partir de las dimensiones: hacinamiento del hogar, calidad de los materiales de la vivienda, carga de dependencia sobre los perceptores de ingresos, las posibilidades de acceso al sistema de salud, y aspectos educativos del hogar. Los resultados obtenidos dan cuenta de que las zonas más alejadas a la región centro son las más postergadas y fundamentalmente los departamentos de la región este de la provincia de Salta. Se destaca la cantidad de hogares que acumulan 2 o más dimensiones de vulnerabilidad.; Throughout its history, Salta has been affected by several disasters, hydrometeorological ones have been the most prevalent. It is accepted that for a disaster situation to happen, a threat must operate on a vulnerable community; i.e., the degree of exposure of a family or a community in case of harmful hazards, and their failure or inability to protect themselves. We performed a descriptive analysis of the database corresponding to the information about the province of Salta gathered through the National Census of Population and Housing 2001, processed with Redatam + SP Process. Indexes were made according to the methodology employed by Melina Con, based on sizes: overcrowding, quality of building materials, dependency burden on income earners, access to health care, and learning aspects of the home. Results show that the furthest areas from the central region are the most neglected ones, mainly those in the eastern area of the province of Salta. An important number of households accumulate 2 or more dimensions of vulnerability.

Effect of antibiotics against Mycoplasma sp. on human embryonic stem cells undifferentiated status, pluripotency, cell viability and growth Romorini, Leonardo; Riva, Diego Ariel; Bluguermann, Carolina; Videla Guillermo, Richardson; Scassa, Maria Elida; Sevlever, Gustavo; Miriuka, Santiago Gabriel Human embryonic stem cells (hESCs) are self-renewing pluripotent cells that can differentiate into specialized cells and hold great promise as models for human development and disease studies, cell-replacement therapies, drug discovery and in vitro cytotoxicity tests. The culture and differentiation of these cells are both complex and expensive, so it is essential to extreme aseptic conditions. hESCs are susceptible to Mycoplasma sp. infection, which is hard to detect and alters stem cell-associated properties. The purpose of this work was to evaluate the efficacy and cytotoxic effect of PlasmocinTM and ciprofloxacin (specific antibiotics used for Mycoplasma sp. eradication) on hESCs. Mycoplasma sp. infected HUES-5 884 (H5 884, stable hESCs H5-brachyury promoter-GFP line) cells were effectively cured with a 14 days PlasmocinTM 25 µg/ml treatment (curative treatment) while maintaining stemness characteristic features. Furthermore, cured H5 884 cells exhibit the same karyotype as the parental H5 line and expressed GFP, through up-regulation of brachyury promoter, at day 4 of differentiation onset. Moreover, H5 cells treated with ciprofloxacin 10 µg/ml for 14 days (mimic of curative treatment) and H5 and WA09 (H9) hESCs treated with PlasmocinTM 5 µg/ml (prophylactic treatment) for 5 passages retained hESCs features, as judged by the expression of stemness-related genes (TRA1-60, TRA1-81, SSEA-4, Oct-4, Nanog) at mRNA and protein levels. In addition, the presence of specific markers of the three germ layers (brachyury, Nkx2.5 and cTnT: mesoderm; AFP: endoderm; nestin and Pax-6: ectoderm) was verified in in vitro differentiated antibiotic-treated hESCs. In conclusion, we found that PlasmocinTM and ciprofloxacin do not affect hESCs stemness and pluripotency nor cell viability. However, curative treatments slightly diminished cell growth rate. This cytotoxic effect was reversible as cells regained normal growth rate upon antibiotic withdrawal.

"Prosperidad y espiritualismo para todos": un análisis sobre la noción de emprendedor en eventos masivos de Buenos Aires Vargas, Patricia Beatriz; Viotti, Nicolas Este artículo pretende contribuir al análisis del valor del emprendedurismo en las sociedades modernas contemporáneas. A partir del retrato etnográfico de grandes eventos públicos realizados en la ciudad de Buenos Aires vinculados con el emprendedurismo empresarial y las espiritualidades alternativas, se enfatizan aquí dos dimensiones específicas: los valores de la realización personal, concentrados en la búsqueda de prosperidad, y el modo en que los grandes eventos promueven formas novedosas de socialidad entre colectivos identificados con las clases medias.; This article discusses the value of entrepreneurship in contemporary modern societies. From an ethnographic portrait of big public events in the city of Buenos Aires associated with business entrepreneurship and alternative spirituality. We emphasize two particular dimensions: the values of self-realization, focused on finding prosperity, and the way in which big events promote new forms of sociality among groups identified with urban middle classes.

Genetic diversity of phosphate-solubilizing peanut (Arachis hypogaea L.) associated bacteria and mechanisms involved in this ability Anzuay, María Soledad; Frola, Ornella; Angelini, Jorge Guillermo; Ludueña, Liliana Mercedes; Fabra, Adriana Isidora; Taurian, Tania In this study, attempts were made to analyze mechanisms involved in the bacterial phosphate-solubilizing ability of peanut isolates. Bacteria were taxonomically identified by analysis of 16S rDNA sequence. Levels of soluble P released by the isolates in unbuffered or buffered with Tris–HCl or MES NBRIP-BPB medium as well as the production of D-gluconic acid were determined in their culture. Presence of two of the genes encoding the cofactor PQQ of GDH enzyme was analyzed in the genome of this bacterial collection. 16S rDNA sequence analysis indicated that isolates belong to genera Serratia, Enterobacter, Pantoea, Acinetobacter, Bacillus and Enterococcus. All bacteria showed ability to solubilize tricalcium phosphate either in unbuffered or buffered medium. Nevertheless, addition of buffer solutions reduced levels of Pi liberated by the isolates. Although almost all isolates produced detectable amounts of D-gluconic acid, no correlation with levels of P soluble released were observed. The presence of pqqE and pqqC genes was detected only in Gram negative bacteria. It was concluded from this study that the mechanism involved in phosphate solubilization is organic acids production and, presence of pqq genes in all Gram negative bacteria analyzed encourages to confirm their role in bacterial phosphate solubilizing ability as well to identify genes involved in this PGP trait in Gram positive bacteria.

Agricultura familiar y políticas públicas en la Argentina de los últimos años: algunas reflexiones en torno a una relación compleja; Family farm and public policies in Argentina in recent years: some reflections on a complex relationship Nogueira, Maria Elena El siguiente trabajo pretende contribuir a la discusión actual sobre agricultura familiar. Este tipo de producción ha sido materia de infinidad de análisis y tiene, en la actualidad de las políticas orientadas al desarrollo rural en Argentina, una gran relevancia. En el último tiempo ha habido en ellas un viraje que, al menos en términos propositivos, permite pensar al sujeto de la agricultura familiar con una mirada mayormente anclada en aspectos territoriales, culturales y políticos que en buena medida resultan novedosos y habilitan a considerar más exhaustivamente esta porción de la estructura social agraria. El trabajo tiene como objetivo discutir los usos de esta categoría, poniendo especial énfasis en las políticas públicas que se orientan a estos sujetos en la actualidad. Para ello, se analizaron fuentes oficiales al respecto y una serie de trabajos académicos relevantes para la realidad de Argentina y buena parte de América Latina.; This paper aims to contribute to the ongoing discussion on family farm. This type of production has been the subject of analysis and has a great importance in rural development-oriented policies in Argentina. In recent times there has been a change in its treatment, at least in propositional terms that suggests the inclusion of territorial aspects, cultural and political factors that are largely new and enabled to consider more thoroughly this portion of the agrarian social structure. The paper aims to discuss the use of this category, with special emphasis on public policies that focus on these kind of subjects today. To do this, we analyzed official documents connected with the topic and a series of papers relevant to the reality of Argentina and part of Latin America.

Gas phase imidazole methylation on zeolites and HPA/SiO2: Study of acid site requirements and catalyst deactivation Vanoy Villamil, Michael Nicolás; Apesteguia, Carlos Rodolfo; Padro, Cristina The gas-phase alkylation of imidazole with methanol was studied at 523 K on solid acids such as HPA/SiO2 and zeolites HMCM22, HBEA, NaY, ZnY and HY. The nature, density and strength of acid sites were determined by temperature programmed desorption of NH3 coupled with infrared spectra of adsorbed pyridine. Coke formation was studied by temperature programmed oxidation technique. On all the samples, the selectivity to N-methylimidazole was greater than 98%. Catalysts presenting essentially Lewis (NaY and ZnY) or Brønsted (HPA/SiO2) acidity did not promote efficiently the methylation of imidazole and yielded less than 20% of N-methylimidazole. In contrast, on samples containing similar concentration of Lewis and Brønsted acid sites (HY, HBEA, HMCM22) the N-methylimidazole yield was between 60 % (HMCM22) and 100% (HY). All the samples deactivated during the 4 h catalytic tests and formed significant amounts of coke, between 2.3% (NaY) and 8% (ZnY). Catalytic tests performed at different contact times showed that the initial activity decay diminished with increasing imidazole conversion, suggesting that catalyst deactivation is mainly related with the presence of the reactants, methanol and/or imidazole. In order to gain insight on the catalyst deactivation mechanism, additional catalytic tests using different feed compositions were performed. They showed that the initial catalyst deactivation followed a linear correlation with the partial pressure of imidazole which indicated that the activity decay is essentially related with strong adsorption of imidazole the on surface acid sites.

Can nest predation explain the lack of defenses against cowbird brood parasitism in the Rufous-collared sparrow (Zonotrichia capensis)?; ¿Puede la depredación de nidos explicar la falta de defensas de Zonotrichia capensis contra el parasitismo de cría de M. Bonariensis? Carro, Mariana Emilia; Fernandez, Gustavo Javier Although interspecific avian brood parasitism usually lowers host productivity, some species lack any defense against parasites. We analyzed the effect of parasite egg removal or nest desertion following a parasitism event on the breeding productivity of the Rufous-collared Sparrow (Zonotrichia capensis), a common host of the Shiny Cowbird (Molothrus bonariensis). The Rufouscollared Sparrow is an effective cowbird host that does not eject parasite eggs. We removed cowbird eggs from nests of Rufouscollared Sparrows to test for differences in hatching, fledging, and nesting success among naturally unparasitized, parasitized, and experimentally unparasitized nests from which we removed the cowbird eggs. We also used simulations to test whether parasite egg removal or nest desertion provide viable strategies to counter the effects of parasitism in this species. Naturally unparasitized nests produced more nestlings and fledglings than parasitized and experimentally unparasitized nests, but there were no differences between parasitized nests and those from which cowbird eggs were removed. Moreover, the overall nesting success was similar for all nest types. Simulation models confirmed these results but also showed that productivity may still increase through parasite egg ejection when the nest predation rate is relaxed only if no cost of parasite egg ejection is assumed. By contrast, nest desertion was not a viable strategy to reduce the effect of parasitism. We suggest that high nest predation could reduce the benefits of antiparasite defenses in the Rufouscollared Sparrow and may help explain the lack of such behavior in this species.; A pesar de que el parasitismo de cría interespecífico usualmente reduce la productividad de las especies hospedadoras, algunas de estas especies carecen de defensas contra los parásitos. En este trabajo analizamos el efecto que la remoción de huevos de los parásitos de cría y la deserción del nido siguiendo un evento de parasitismo podrían tener sobre la productividad de Zonotrichia capensis, una especie hospedadora común de Molothrus bonariensis. Esta especie es un hospedador efectivo de M. bonariensis y no rechaza los huevos del parásito de su nido. Realizamos la remoción de los huevos del parásito de nidos de Z. capensis, y comparamos el éxito de eclosión, de volantoneo y de nidificación de nidos naturalmente no parasitados, nidos parasitados y aquellos donde realizamos la remoción del huevo parásito. Además, utilizamos modelos de simulación para evaluar si la remoción de huevos del parásito y la deserción del nido podrían constituir estrategias viables para reducir los efectos del parasitismo de cría en esta especie. Los nidos naturalmente no parasitados produjeron más pichones y volantones que los nidos experimentales ïlos parasitados, pero no existieron diferencias entre estos dos últimos tipos de nidos. Además, el éxito de nidificación fue similar para los distintos tipos de nidos. A pesar de la falta de diferencias detectada en el experimento a campo, los modelos de simulación demostraron también que, cuando la tasa de depredacióon de nidos es menor, la productividad puede aún incrementarse si Z. capensis rechaza los huevos del parásito siempre y cuando no exista un costo en el comportamiento de rechazo. En cambio, la deserción del nido no fue una estrategia viable para reducir el impacto del parasitismo. Sugerimos que la alta tasa de depredación de nidos podría reducir los beneficios de las defensas antiparasitarias en Z. capensis y puede contribuir a explicar la falta de ellas en esta especie.

An efficient synthesis of 1α,25-dihydroxy-20-epi-vitamin D3 Fraga, R.; López Pérez, B.; Sokolowska, K.; Ghini, Alberto Antonio; Regueira, T.; Diaz, S.; Mouriño, A.; Maestro, M. A. The synthesis of 1,25-dihydroxy-20-epi-vitamin D3 (1) by Pd(0)-catalyzed coupling between the boronate ester (2) and the enol triflate (3) is described. This article is part of a Special Issue entitled ‘Vitamin D Workshop’.

Thermophysical properties for the ternary systems toluene (1) + benzene (2) + methyl acetate (3), at various temperatures from 288.15 K to 318.15 K Mariano, Alejandra Beatríz; Mussari, Lelia María Ester; Camacho, Alberto Gustavo; Canzonieri, Salvador Humberto; Postigo, Miguel Angel Density, speed of sound and viscosity for the ternary system formed by toluene, benzene and methyl acetate and their corresponding binaries were measured at atmospheric pressure in the temperature range of 288.15 K to 318.15 K, every 5 K. Experimental data were used to calculate derived properties: excess molar volume, isentropic compressibility, isentropic compressibility deviation, viscosity deviation and excess free energy of activation for viscous flow. These magnitudes were fitted to different equations available in the literature. In addition, geometrical models have been used to predict ternary magnitudes. Predictions of viscosities for the ternary system were performed by group contribution models. Molecular interactions among the components of the mixtures were inferred from the sign of the excess and deviation properties.