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.

Correlation between thermal parameters, structures, dendritic spacing and corrosion behavior of Zn-Al alloys with columnar to equiaxed transition Ares, Alicia Esther; Gassa, Liliana Mabel; Gueijman, Sergio Fabian; Schvezov, Carlos Enrique The columnar to equiaxed transition (CET) has been examined for many years and the significance of CET has been treated in several articles. Experimental observations in different alloy systems have shown that the position of the transition is dependent on parameters like cooling rate, velocity of the liquidus and solidus fronts, local solidification time, temperature gradients and recalescence. The dendritic structure in alloys results in microsegregation of solute species which affects significantly the mechanical properties of the material. The main parameters characterizing the microstructure and the length range of microsegregation is the spacing which is classified as primary, secondary and tertiary. Properties like mechanical resistance and ductility are influenced by the dimensions and continuity of the primary branches, while the secondary and tertiary branches permit the isolation of interdendritic phases which can deteriorate the mechanical behavior of the material. Since the morphology and dimensions of the dendritic structure is related to the solidification parameters mentioned above, for each type of alloy it is essential to correlate dimensions and solidification conditions in order to control the structure. The objective of the present research consists on studying the influence of solidification thermal parameters with the type of structure (columnar, equiaxial or with the CET); and with grain size and dendritic spacing (primary and secondary) in Zn-Al (ZA) alloys (Zn-4 wt%Al, Zn-16 wt%Al and Zn-27 wt%Al, weight percent). Also, correlate the thermal parameters, type of structure, grain size and dendritic spacing with the corrosion resistance of these alloys. © 2007 Elsevier B.V. All rights reserved.

Novel aromatic ring-hydroxylating dioxygenase genes from coastal marine sediments of Patagonia Lozada, Mariana; Riva Mercadal, Juan Pablo; Guerrero, Leandro Demián; Di Marzio, Walter Dario; Ferrero, Marcela Alejandra; Dionisi, Hebe Monica Polycyclic aromatic hydrocarbons (PAHs), widespread pollutants in the marine environment, can produce adverse effects in marine organisms and can be transferred to humans through seafood. Our knowledge of PAH-degrading bacterial populations in the marine environment is still very limited, and mainly originates from studies of cultured bacteria. In this work, genes coding catabolic enzymes from PAH-biodegradation pathways were characterized in coastal sediments of Patagonia with different levels of PAH contamination.Genes encoding for the catalytic alpha subunit of aromatic ring-hydroxylating dioxygenases (ARHDs) were amplified from intertidal sediment samples using two different primer sets. Products were cloned and screened by restriction fragment length polymorphism analysis. Clones representing each restriction pattern were selected in each library for sequencing. A total of 500 clones were screened in 9 gene libraries, and 193 clones were sequenced. Libraries contained one to five different ARHD gene types, and this number was correlated with the number of PAHs found in the samples above the quantification limit (r = 0.834, p < 0.05). Overall, eight different ARHD gene types were detected in the sediments. In five of them, their deduced amino acid sequences formed deeply rooted branches with previously described ARHD peptide sequences, exhibiting less than 70% identity to them. They contain consensus sequences of the Rieske type [2Fe-2S] cluster binding site, suggesting that these gene fragments encode for ARHDs. On the other hand, three gene types were closely related to previously described ARHDs: archetypical nahAc-like genes, phnAc-like genes as identified in Alcaligenes faecalis AFK2, and phnA1-like genes from marine PAH-degraders from the genus Cycloclasticus.Conclusion: These results show the presence of hitherto unidentified ARHD genes in this sub-Antarctic marine environment exposed to anthropogenic contamination. This information can be used to study the geographical distribution and ecological significance of bacterial populations carrying these genes, and to design molecular assays to monitor the progress and effectiveness of remediation technologies.

Aspectos gramaticales del español (morfosintácticos y léxico-semánticos) en la formación del traductor Albano, Hilda Rosa; Giammatteo, Graciela Mabel En este trabajo se parte del debate acerca de la pertinencia de las cuestiones gramaticales en la formación del traductor y se defiende una posición que sostiene que el aprendizaje de la gramática del español es esencial para lograr que el trabajo del traductor resulte plenamente eficaz. Asimismo se propone un enfoque léxico-sintáctico de la gramática, que se ejemplifica con un aspecto central nuclear: la incidencia del verbo en la organización sintáctico-semántica de la oración y en la selección de los modificadores que lo acompañan.

Short-time transport properties in dense suspensions: From neutral to charge-stabilized colloidal spheres Banchio, Adolfo Javier; Nägele, Gerhard We present a detailed study of short-time dynamic properties in concentrated suspensions ofcharge-stabilized and of neutral colloidal spheres. The particles in many of these systems are subjectto significant many-body hydrodynamic interactions. A recently developed accelerated Stokesiandynamics (ASD) simulation method is used to calculate hydrodynamic functions,wave-number-dependent collective diffusion coefficients, self-diffusion and sedimentationcoefficients, and high-frequency limiting viscosities. The dynamic properties are discussed independence on the particle concentration and salt content. Our ASD simulation results are comparedwith existing theoretical predictions, notably those of the renormalized density fluctuation expansionmethod of Beenakker and Mazur [Physica A 126, 349 (1984)], and earlier simulation data on hardspheres. The range of applicability and the accuracy of various theoretical expressions for short-timeproperties are explored through comparison with the simulation data. We analyze, in particular, thevalidity of generalized Stokes?Einstein relations relating short-time diffusion properties to thehigh-frequency limiting viscosity, and we point to the distinctly different behavior of de-ionizedcharge-stabilized systems in comparison to hard spheres.

Une nouvelle espèce du genre Neostenotus d'Argentine (Heteroptera, Miridae, Mirini) Chérot, Frédéric; Carpintero, Diego Leonardo Une nouvelle espèce, Neostenotus querandi n. sp., est décrite de Buenos-Aires, Argentine.

Heat shock factor 1 represses estrogen-dependent transcription through association with MTA1 Khaleque, M. A.; Bharti, A.; Gong, J.; Gray, P. J.; Sachdev, V.; Ciocca, Daniel Ramon; Stati, Arturo Oscar; Fanelli, Mariel Andrea; Calderwood, S. K. Heat shock factor 1 (HSF1), the transcriptional activator of the heat shock genes, is increasingly implicated in cancer. We have shown that HSF1 binds to the corepressor metastasis-associated protein 1 (MTA1) in vitro and in human breast carcinoma samples. HSF1-MTA1 complex formation was strongly induced by the transforming ligand heregulin and complexes incorporated a number of additional proteins including histone deacetylases (HDAC1 and 2) and Mi2α, all components of the NuRD corepressor complex. These complexes were induced to assemble on the chromatin of MCF7 breast carcinoma cells and associated with the promoters of estrogen-responsive genes. Such HSF1 complexes participate in repression of estrogen-dependent transcription in breast carcinoma cells treated with heregulin and this effect was inhibited by MTA1 knockdown. Repression of estrogen-dependent transcription may contribute to the role of HSF1 in cancer.