Recovery of normal cytogenetic records in mussels after cessation of pollutant effluents in Puerto Madryn (Patagonia, Argentina)
Machado Schiaffino, Gonzalo; Bala, Luis Oscar; Garcia Vazquez, Eva
The capacity of coast recovering after interruption of pollution sources has been explored employing mussels as biomarkers. In an area polluted by sewage sludge in Puerto Madryn (Argentina), abnormally high cytogenetic records (micronuclei) had been detected in the mussel Mytilus edulis, even higher than those obtained in this and other mussel species (Brachydontes rodriguezi, Aulacomya atra atra, Perumytilus purpuratus) sampled from heavily polluted industrial areas, and much higher than those recorded in samples from unpolluted areas of the same region. Normal cytogenetic patterns were recovered in Puerto Madryn less than 1 year after cessation of sewage sludge discharges, without additional treatment of the affected area. This discovery opens the possibility of considering restored coastal areas for aquaculture purposes instead of endangering natural populations in virgin areas.
Experimental and theoretical investigation of anaerobic fluidized bed biofilm reactors
Fuentes, M.; Mussati, Miguel Ceferino; Aguirre, Pio Antonio; Scenna, Nicolas Jose
This work presents an experimental and theoretical investigation of anaerobic fluidized bed reactors (AFBRs). The bioreactors are modeled as dynamic three-phase systems. Biochemical transformations are assumed to occur only in the fluidized bed zone. The biofilm process model is coupled to the system hydrodynamic model through the biofilm detachment rate; which is assumed to be a first-order function of the energy dissipation parameter and a second order function of biofilm thickness. Non-active biomass is considered to be particulate material subject to hydrolysis. The model includes the anaerobic conversion for complex substrate degradation and kinetic parameters selected from the literature. The experimental set-up consisted of two mesophilic (36±1°C) labscale AFBRs (R1 and R2) loaded with sand as inert support for biofilm development. The reactor start-up policy was based on gradual increments in the organic loading rate (OLR), over a four month period. Step-type disturbances were applied on the inlet (glucose and acetic acid) substrate concentration (chemical oxygen demand (COD) from 0.85 to 2.66 g L -1) and on the feed flow rate (from 3.2 up to 6.0 L d-1) considering the maximum efficiency as the reactor loading rate switching. The predicted and measured responses of the total and soluble COD, volatile fatty acid (VFA) concentrations, biogas production rate and pH were investigated. Regarding hydrodynamic and fluidization aspects, variations of the bed expansion due to disturbances in the inlet flow rate and the biofilm growth were measured. As rate coefficients for the biofilm detachment model, empirical values of 3.73?104 and 0.75?104 s2 kg -1 m-1 for R1 and R2, respectively, were estimated.
Las extraordinarias variaciones del Opus 111: Motivos adornianos en torno al estilo tardío de Beethoven
Quintana, María Marta
El propósito del presente artículo es retomar las consideraciones de Theodor W. Adorno acerca del estilo tardío de Beethoven. El análisis se centra principalmente en las referencias al Opus 111, por tratarse de "una sonata difícil de comprender como obra espiritualmente equilibrada". Indagando en la tesis del filósofo, se busca desentrañar algunos de los presupuestos estético-filosóficos, tales como: la negatividad de la obra de arte y su función crítica. El trabajo se divide en dos momentos: el primero, ubica el pensamiento de Adorno en el marco de la Escuela de Frankfurt (I), y luego avanza sobre la caracterización y análisis del estilo medio (II); el segundo movimiento, se introduce propiamente en el estilo tardío del compositor.; Cet article examine les thèses de h. Adorno à propos du style tardif de Beethoven. L’analyse s’occupe particulièrement des références à l’Op. 111 –considéré par l’auteur comme une oeuvre diicile à comprendre du point de vue de l´esthétique classique– et cherche à approfondir quelques présuppositions esthético-philosophiques d’Adorno, tels que la négativité de l’oeuvre d’art et sa fonction critique de la société.
Los conglomerados sintectónicos de la formación las cumbres (Plio-Pleistoceno), sierras pampeanas de La Rioja y Catamarca, Argentina.; Stratigraphy and tectonic inversión of the Neogene rift in Campo del Arenal, Catamarca, NW Argentina
Bossi, Gerardo Eugenio; Georgieff, Sergio Miguel; Muruaga, Claudia Marcela; Ibañez, Lucía Marina; Sanagua, Javier G.
La Formación Las Cumbres (Plio-Pleistoceno) aflora extensamente en el área comprendida entre lassierras de Velasco y Paimán al sur y las sierras de Vinquis y Zapata al norte (Provi ncias de Catamarca y La Rioja, NO Argentina) cubriendo concordantemente la Formación Salicas (Mioceno tardío-Plioceno temprano). La Formación Las Cumbres es una sucesión granocreciente de conglomerados y areniscas que desarrollan una gran bajada aluvial formada durante el pico del levantamiento de las Sierras Pampeanas. En el sector sureste del área estudiada (las Cumbres de los Pozuelos), la falla transpresiva Uscamayo creó cuatro alounidades locales separadas por discordancias angulares (progresivas), en el bloque hundido. Cada alounidad constituye un estadio de actividad tectónica intensa, mientras que las discordancias representan etapas intermedias de intensa erosión y pedimentación. Se han distinguido dos facies sedimentarias principales: 1. conglomerados de milonitas angulosas y granitos deformados que dominan
la parte sur del sistema de dispersión y 2. conglomerados polimícticos redondeados (granitos, esquistos, volcanitas, metavolcanitas y milonitas) que corresponden al sector norte. Las facies 1 provienen de las sierras de Velasco, cerro La Punta y Paimán, mientras que las facies 2 derivan del conjunto de sierras integradas por Vinquis, Zapata, Copacabana y Cerro Negro. Los dos sistemas convergen hacia el área de las Cumbres de los Pozuelos para hundirse allí en
el 'Bolsón de Pipanaco'. Estos sistemas de dispersión no son congruentes con la posición actual de las sierras que han sufrido desplazamientos importantes en sentido norte-sur durante la etapa más intensa de levantamiento, ocurrida en
el Pleistoceno temprano y 'medio'; The Santa María-Hualfín Basin in the NW Pampean Ranges started during the extensional faulting of a large NNW-SSE elongated dome, developed abo ve a peneplained basement. The faulted blocks were tilted outwards from the axis of the dome. Subsequently, the Neogene sedimentation (Santa María Group) was concentrated along listric faults bounding hemigrabens, reaching up to 3,000 m thick in these áreas. An intrabasin volcanic event occured during 11-6 Ma and was associated to asthenospheric upwelling and crustal thickening. A change from extensional to compressive tectonism, represented by the Intra-Aldalhuala disconformity, occurred at 4.8-5.2 Ma, resulting in approximately 9% shortening. Subsequently, during Pliocene times, thermal subsidence took place.
El sistema lacustre de la Formación Mollar en el depocentro triásico de Santa Clara (provincia de Mendoza, Argentina); The lacustrine system of the Mollar Formation in the Triassic Santa Clara Depocenter (Mendoza Province, Argentina)
Spalletti, Luis Antonio; Zavattieri, Ana Maria
El depocentro triásico de Santa Clara, Cuenca Cuyana, se caracteriza por espesos depósitos generados en ambiente lacustre. Uno de ellos, con un registro de más de 345 m, corresponde a la Formación Mollar. El tramo inferior a medio está caracterizado por una monótona sucesión de lutitas bituminosas acumuladas por decantación suspensiva en el ?offshore? anóxico de un cuerpo lacustre hidrológicamente cerrado y que muestra alto contenido de materia orgánica amorfa de origen algal y de restos de plantas terrestres muy degradadas junto a sulfuros de hierro autígenos. Intercalan
areniscas finas debidas a corrientes de turbidez diluidas y carbonatos estromatolíticos. En esta sucesión se definen ciclos granocrecientes de pequeña escala (PACs) que se atribuyen a episodios de expansión-retracción lacustre controlados por cambios climáticos. Asociaciones de facies heterolíticas representan los depósitos de la transición entre los ambientes de ?nearshore? y ?offshore? lacustre. La sección superior de la Formación Mollar se compone de sucesiones políticas con profusa bioturbación que sugieren mayor oxigenación del sustrato y se asignan a ambiente de costa afuera de un sistema lacustre holomíctico hidrológicamente abierto. Intercalan areniscas producto de flujos hiperpicnales. Depósitos de areniscas con abundantes trazas fósiles y estructuras de olas y flujos unidireccionales, representan a sectores marginales del ambiente lacustre. Además de los ciclos de alta frecuencia, en la Formación Mollar se definen tres secuencias asimétricas de mayor escala atribuidas a episodios mayores de expansión-contracción lacustre debidos a la interacción entre factores climáticos y tectónicos. El diseño de superposición granocreciente de la Formación Mollar y la gradual transición a depósitos fluviales de la sobreyacente Formación Montaña refleja asimismo una constante reducción del espacio de acomodación sedimentaria en el depocentro de Santa Clara a medida que se produjo la acumulación de los depósitos estudiados.; The Triassic Santa Clara depocenter, Cuyo Basin, is characterised by thick fine-grained deposits formed in lacustrine systems. One of them, represented by the Mollar Formation, exceeds the 345 m. The lower to middle section of this unit is dominated by a monotonous succession of black shales having a high content of amorphous organic matter produced by algae and highly degraded plant remains. These deposits were formed by suspension fallout in the anoxic ‘offshore’ sector of a hydrologically closed lake. Thin and fine-grained turbiditic beds and stromatolitic carbonates are intercalated in the fine-grained succession. Small-scale coarsening-upward cycles (PACs) are attributed to episodes of lake expansion-retraction driven by climate change. A facies association composed of an heterolithic package represents the deposits of the transition between ‘nearshore’ and ‘offshore’ settings. The upper section of the
Mollar Formation essentially consists of bioturbated mudstones suggesting a greater oxygenation of the substrate. They are assigned to the ‘offshore’ environment of a holomictic hydrologically open lake system. Sporadic hyperpycnal flows are documented by intercalations of sandy turbidites. Bioturbated sandstone beds with primary structures indicative of both normal and storm wave action and unidirectional flows, represent the marginal deposits of the lacustrine system. In addition to the high-frequency cycles, three larger scale asymmetrical sequences are identified in the Mollar Formation. These sequences suggest episodes of major expansion-contraction of the lake system due to the interaction between climatic and tectonic factors. The overall shallowing up stacking pattern of the Mollar Formation and the gradual transition to fluvial deposits of the overlying Montaña Formation reflects a steady reduction of accommodation space in the Santa Clara depocenter during the accumulation of the studied succession
El desarrollo de la escritura de palabras en español: Interacción entre el conocimiento fonológico y ortográfico; Spelling development in Spanish: Interaction between phonological and orthographic knowledge
Sanchez Abchi, Veronica Soledad; Diuk, Beatriz Graciela; Borzone, Ana Maria; Ferroni, Marina Valeria
Este trabajo se propone ampliar los conocimientos acerca de las estrategias que utilizan los niños en la tarea de escritura de palabras en español. Para ello se analizó, en dos experimentos, de qué manera incidían las variables de complejidad, extensión y frecuencia de las palabras en la escritura al dictado. Asimismo, se analizó la interacción entre las variables fonológicas y el conocimiento ortográfico en el aprendizaje temprano de la escritura. Se aplicaron pruebas de escritura de palabras a 59 niños al finalizar el primer año y nuevamente al terminar el segundo año de la EGB. Los resultados mostraron que los mecanismos fonológicos son fundamentales en la primera etapa de aprendizaje de la escritura. Al finalizar el 2do año escolar se observó también una interacción entre los mecanismos fonológicos y léxicos.; This study analyzed the acquisition of word spelling strategies in Spanish-speaking children, during the first two years of elementary education. The cognitive word spelling models, initially developed for English, describe different stages in the acquisition spelling process. In the first stage, children write by memory, reproducing visual cues. At a second stage, children analyze the phonological structure of the word. Finally, in an orthographic stage, children can write words, using lexical information, without phonological mediation (Frith, 1984, 1985; Marsh, Friedman, Welch & Desberg, 1980). Even when the stages theory was discussed, these first studies allowed the identification of early lexical strategies and phonological mechanisms implied in the English word spelling processes. However, English is a language with a deep orthography, and the phonological strategy is a necessary mechanism but it is not enough to spell words properly. On the contrary, the Spanish orthographic system is shallow, and the phonemes-graphemes correspondences are very regular. Consequently, the spelling strategies could be different in these two languages, and the models developed for English would partially explain the orthographic learning process in transparent languages.
This work aims to contribute to the knowledge on early spelling word strategies in Spanish. In two experiments, first and second grade children were given spelling tests designed to explore their phonological and orthographic knowledge. In the first experiment, the incidence of word complexity, length and frequency on spelling performance was explored. However, there was a possibility that, if children performed better in frequent words spelling, in relation to less frequent, they were resorting to their lexical knowledge. In this case, children were using an orthographic-lexical strategy. On the other hand, the possibility of writing complex and long words is associated to the phonological awareness level and correspondence knowledge. If children were able to easily write frequent and non frequent short and simple words, but had difficulties in writing long and complex words, they were possibly analyzing the sounds of the words and thus activating the corresponding letters. If the word was long or complex and the phonological skills were not well developed, children would have difficulties in writing them; one such problem, for example, would be in omitting letters. In this case, complexity and length variables that show the use of an analytic strategy would be influencing the performance. In the first experiment, the orthographic variable was not considered specifically, so a second experiment was designed. The second experiment evaluated orthographic knowledge, considering the orthographic characteristics of the words. The acquisition of the consistent and inconsistent correspondences was compared. The consistent correspondences could be solved using transcription rules, while inconsistent correspondences could be written only through lexical knowledge.
Furthermore, consistent correspondences could be independent or dependent from context. In the first case, we refer to phonemes that are always represented with the same letter. In the other case, transcription depends on the syllabic context.
Tests were applied at the end of the first and the second year of primary education. Results of the first experiment showed that, at the end of the first year, there was no frequency effect but the variables of complexity and length affected the children's performance. At the end of the second year, a frequency effect and a significant interaction between complexity and frequency were found. In the second experiment, a significant consistence effect was observed, but there was no frequency effect. These results indicate that phonological strategies are fundamental in the beginning of spelling acquisition. On the contrary, lexical mechanisms appear later and they are acquired gradually. Indeed, at the end of the first grade, frequency only affected performance of context dependent correspondences, but not independent. Likewise, interaction between phonological and lexical strategies was found only at the end of the second year. Pedagogical implications were also considered.
Coke analysis by temperature-programmed oxidation: Morphology characterization
Sanchez, Barbara Sabrina; Gross, Martin Sebastian; Dalla Costa, Bruno Oscar; Querini, Carlos Alberto
Temperature-programmed oxidation (TPO) profiles obtained using high final temperature are usually very similar in shape and it is not possible to easily distinguish among different kinetic models. Typically, statistical criteria are used to select the one that best fits the experimental TPO profile. In this work, we show that using final temperatures selected in such a way that the coke is still reacting with oxygen, relevant information can be obtained from the experimental profile. Coked naphtha reforming catalysts, obtained from an industrial reactor, are characterized by running TPO analyses using intermediate temperatures. Results clearly show that the coke reaction order changes as the coke conversion increases. When the initial coke content is approximately 5 wt% or higher, coke has a tridimensional structure that leads to a low reaction order, close to 0.2. At high conversion levels, approximately 80%, the coke reaction order starts increasing until reaching a value of 1 at conversion close to 1. This information is easily obtained by plotting the experimental coke reaction order using the data at constant temperature. In this way, it is possible to easily distinguish among different models, and to replicate the experimental results.
Conformational and vibrational analysis of methyl methanesulfonate, CH3SO2OCH3
Tuttolomondo, María Eugenia; Navarro, Amparo; Peña, Tomás; Varetti, Eduardo Lelio; Parker, Stewart F.; Ben Altabef, Aída
The molecular structure of methyl methanesulfonate, CH3SO 2OCH3, has been optimized by using methods based on density functional theory, coupled cluster, and Moller-Plesset second order perturbation theory (MP2). With regard to CH3SO2OCH 3, two populated conformations with symmetries Cs and C1 are obtained, the former being more stable than the latter. The theoretical data indicate that although both anti and gauche conformers are possible by rotation about the S-O bond, the preferred conformation is anti. The total energy as a function of the CSOC dihedral angle has been calculated using the MP2 method with the 6-31G(d) and cc-pVDZ basis sets and the hybrid functional B3LYP using 6-31G(d), 6-311G(d,p), and 6-311++G(d,p) basis sets. A natural bond orbital analysis showed that the lone pair →σ * hyperconjugative interactions favor the anti conformation. Furthermore, the infrared spectra for the liquid and solid phases, the Raman spectrum for the liquid one, and the inelastic neutron scattering spectrum of the solid phase have been recorded, and the observed bands have been assigned to the vibrational modes. The experimental vibrational data, along with calculated theoretical force constants, were used to define a scaled quantum mechanical force field for the target system that enabled us to fit the measured frequencies with a final root-mean-square deviation of 10 cm-1.
(1,1-Dichloro-2,2,2-trifluoroethylimino)sulfur dichloride, CF3CCl2N=SCl2: Vibrational spectra and quantum chemical calculations
Flores Antognini, Andrea; Cutin, Edgardo Hugo; Robles, Norma Lis; Oberhammer, Heinz
The vibrational spectra of (1,1-dichloro-2,2,2- trifluoroethylimino)sulfur dichloride, CF3CCl2N@SCl2, were recorded in the gas phase with IR spectroscopy and in the liquid state with Raman spectroscopy. Quantum chemical calculations at the HF, B3LYP (6-311+G(d) and 6-311+G(2df) basis sets) and MP2 levels of theory (6-31+G(d) and 6-311+G(df) basis sets) were performed. According to all calculations the lowest energy conformer possesses C1 symmetry with syn orientation of the SCl2 group relative to the N-C bondand near-trans orientation of the CF3 group relative to the N=S bond. Calculations predict the presence of a second stable conformer with anticlinal orientation of the SCl2 group which, however, possesses considerably higher energy and is therefore not observed in the analysis of the experimental vibrational spectra. The vibrational spectra were assigned for a single conformer in accordance with these calculations.
Alternate Cu2 and Er2 spin carriers in a carboxylate bridged chain: EPR study
Calvo, Rafael; Rapp, Raul E.; Sartoris, Rosana Patricia; Santana, Ricardo C.; Perec, Mireille
We report powder EPR measurements at 9.48 GHz and temperatures of 4 K e T e 30 K and at 33.86 GHz and T = 300 K for the polymeric compound {[Cu2Er2(L)10(H2O)4] ·3H2O}n (HL ) trans-2-butenoic acid) having alternate Cu2 and Er2 dinuclear units bridged by carboxylates along a chain. Above 70 K, when the ErIII resonance is unobservable and uncoupled from the CuII ions, the spectrum arises from the excited triplet state of antiferromagnetic Cu2 units, decreasing in intensity as T decreases, and disappearing when these units condensate into the singlet ground state. Fit of a model to the spectra at 9.48 and 33.86 GHz and 300 K gives gCu//= 2.379, gCuper = 2.065, DCu= -0.340 cm-1, and ECu ∼ 0 for the g-factors and zero field splitting parameters. From the T dependence of the intensity of the spectrum above 70 K, we obtain JCu-Cu = -336(11) cm-1 for the intradinuclear exchange interaction. Below 50 K, a spectrum attributed to Er2 units appears, narrows, and resolves as T decreases, due to the increase of the spin-lattice relaxation time T1. The spectrum at 4 K allows calculating g values g1=1.489, g2= 2.163, and g3= 5.587 and zero field splitting parameters DEr=-0.237 cm-1 and EEr = 0.020 cm-1. The results are discussed in terms of the properties of the Cu and Er ions, and the crystal structure of the compound.
Crecimiento y caracterización de películas delgadas de tio2 y ti1- xfexo2
Galvis, J.; Ramirez Jimenez, Helena; Montes, J.; Sanchez, L.; Beltran, J.; Barrero, C.; Morales, A.; Gomez, J.; Tirado Mejia, L.; Osorio, J.
Titanium dioxide (TiO2) and Fe-doped titanium dioxide (Ti1-xFexO2) thin films were grown on silicon substrates using the magnetron sputtering Rf (13.56 MHz) technique. The relevant growth parameters for the samples (pressure, power, gas mixture ratio, distance between target-substrate, among others) were found. The plasma deposition environment for the ternary films was characterized by optical emission spectroscopy in order to verify and identify the present species which were iron and titanium. The TiO2 films, deposited on silicon substrates [100], showed an amorphous phase while the ternary films showed low crystallinity. After annealing at 800 °C crystalline phases appeared, rutile in binary films and mixed in ternary films.
Differential cholinoceptor modulation of nitric oxide isoforms in experimentally-induced inflammation of dental pulp tissue
de Couto Pita, Alejandra Karina; Passafaro, D.; Ganzinelli, Sabrina Belen; Borda, Enri Santiago; Borda, Enri Santiago
Aim The aim of the study was to investigate the role of muscarinic acetylcholine receptor (mAChR) activity in the regulation of endothelial (e), neuronal (n) and inducible (i) nitric oxide synthase (NOS) activity and expression in experimentally induced inflammation of rat dental pulp tissue. Methodology Inflammation was induced by application of bacterial lipopolysaccharide (LPS) to the pulp. Extirpated pulp-tissue samples were incubated in saline solution until the various experiments were performed. Saline-treated pulp and healthy pulp tissues were used as controls. NOS activity was measured by the production of [U-14C]-citrulline from [U-14C]-arginine. Nitrite/nitrate assay was evaluated by the conversion of nitrate to nitrite in the presence of nicotinamide adenine dinucleotide phosphate. i-nos, e-nos and n-nos mRNA levels were measured using reversetranscriptase polymerase chain reaction by co-amplification of target cDNA with a single set of primers. Results Application of LPS to the pulp increased NOS activity and nitrate production (P < 0.001), generated by iNOS over-activity and expression. Pilocarpine acting on mAChRs triggered a biphasic action on NOS activity and NO accumulation. At low concentrations, pilocarpine induced a negative effect associated with a decrease in i-nos mRNA level, whilst at high concentration, it produced a positive effect associated with increased e-nos and n-nos mRNA levels. In control pulp tissue, only the positive effect of pilocarpine was observed. Conclusions Irreversible pulpitis changes mAChR conformation increasing its efficiency of coupling to transducing molecules that in turn induce activate iNOS. The capacity of pilocarpine to prevent NO accumulation and iNOS activity, by acting on mAChR mutation induced by pulpitis, might be useful therapeutically as a local treatment.
The K-theory of toric varieties
Cortiñas, Guillermo Horacio; Haesemeyer, C.; Walker, M. E.; Weibel, C.
Recent advances in computational techniques for K-theory allow us to describe the K-theory of toric varieties in terms of the K-theory of fields and simple cohomological data.
Familia y Heteronormatividad
Guerra, Luciana Analía
Desde diferentes disciplinas y perspectivas es estudiada una institución tan compleja y dinámica como la familia. Abordajes estadísticos, antropológicos, sociológicos, históricos, intentan comprender y analizar la diversidad de estructuras familiares. Incluso, estos estudios, cambiaron la noción de “familia” por el de “organizaciones familiares” para evitar caer en definiciones ahistóricas y monolíticas que pretenden instalar como “natural” una única manera de agrupamiento familiar. Sin embargo, la feminista marxista Heidi Hartmann, considera que estas investigaciones históricas, sociológicas y antropológicas, abordan las organizaciones familiares como unidades cuyos miembros comparten intereses, minimizando la conflictividad que pueda darse entre los mismos. Este punto de partida teórico no es favorable para visibilizar y comprender la situación concreta de las mujeres en el seno familiar. A partir de los aportes de los Estudios de Género y de la teoría feminista, la familia va a ser cuestionada y denunciada como ámbito de dominación masculina por excelencia dónde el mandato patriarcal de ser madre opera como eje organizador de la vida de las mujeres. Las relaciones de poder, las jerarquías por edad y sexo, la Heterosexualidad Obligatoria, la división sexual del trabajo, el trabajo doméstico no remunerado, la transmisión de valores patriarcales, la producción del binarismo sexual y la reproducción de los estereotipos de género en el proceso de socialización, son algunas de las categorías producidas por la teoría feminista para visibilizar los mecanismos de subordinación de las mujeres. Lejos de considerar a la familia como una unidad armónica con intereses comunes, esta perspectiva pone de manifiesto los conflictos y las tensiones existentes en la misma. Teniendo en cuenta los cambios económicos y políticos de los últimos tiempos y el impacto que los mismos han tenido en la estructuración de las familias, intentaré analizar, en qué medida, la familia continúa siendo o no una institución medular del sistema patriarcal, reproductora del orden heteronormativo. Con esto, nos referimos a un orden construido a partir de un sistema sexual binario y jerárquico: mujeres / femeninas / inferiores y varones / masculinos / superiores, reforzado, a su vez, por la esencialización de la sexualidad a través de la imposición de la Heterosexualidad Obligatoria. En definitiva, este sistema sexo-género como lo denominó Gayle Rubin, no sólo limita la definición de lo humano a dos categorías genéricas, varones y mujeres, sino que también disciplina el deseo sexual para que los sexos opuestos se atraigan mutuamente. Resulta de suma importancia para nuestro análisis, señalar que la heteronormatividad del patriarcado conduce a la discriminación e inferiorización tanto de toda orientación sexual disidente, como de cualquier identidad genérica que no respete la dicotomía varón-mujer –léase: travestis, transexuales, intersexuales, transgéneros, lesbianas, bisexuales, gays. Un recorrido por la realidad cotidiana de éstos colectivos humanos, nos permitirá analizar en qué sentido la “crisis de la familia” de la que tanto se habla tiene que ver con una apertura ideológica respetuosa de las múltiples maneras de vivir, construir y habitar las comunidades denominadas familias, o responde al alarmismo nostálgico de mentes conservadoras que perderían muchos privilegios si la “familia tradicional” deja de ser modelo y ejemplo de vida para las futuras generaciones.
El registro biológico humano de la costa meridional de Santa Cruz
Suby, Jorge Alejandro; Guichon, Ricardo Anibal; Zangrando, Atilio Francisco Javier
La costa patagónica constituye un sector de riesgo para el registro arqueológico, asociado a factores naturales y antrópicos. Al mismo tiempo, la conservación de las colecciones bioarqueológicas, destacándose la pérdida de restos óseos e información asociada por escasez de recursos, desconocimiento o falta de atención especializada, representa escenarios de riesgo para el registro. Una de las áreas para las cuales no se dispone hasta el momento de información bioarqueológica es la región que comprende la costa meridional de la provincia de Santa Cruz. Considerando esta ausencia de información, el objetivo de este trabajo es presentar y discutir los primeros resultados sobre restos óseos humanos hallados en la región costera próxima a la desembocadura del Rio Santa Cruz (Santa Cruz, Argentina). Los estudios incluyen el análisis de las situaciones de hallazgo y riesgo de los restos recuperados en acciones de rescate, el reconocimiento y puesta en valor de materiales depositados en el Museo Regional Carlos Borgialli (Puerto Santa Cruz, Santa Cruz, Argentina) y estudios paleopatológicos. Al mismo tiempo se informan y analizan resultados cronológicos e isotópicos. Los resultados brindan evidencias claras de la ocupación de la región costera al menos durante los últimos 2000 años, consumo de recursos predominantemente terrestres y un estilo de vida que favorece el desarrollo de lesiones articulares con escasos indicios de stress sistémico que coinciden con los resultados reportados para la región continental del estrecho de Magallanes.
Hydrosilylation of C-C multiple bonds using (Me3Si) 3SiH in water: Comparative study of the radical initiation step
Postigo, Jose Alberto; Kopsov, Sergey; Zlotsky, Simon S.; Ferreri, Carla; Chatgilialoglu, Chryssostomos
The classical radical-based hydrosilylation reaction of organic compounds bearing C-C multiple bonds is usually carried out in organic solvents and is herein presented in water with both organic solventsoluble and water-soluble substrates. Different initiation methods to accomplish the radical-induced hydrosilylation reaction of C-C multiple bonds in water with (Me 3Si)3SiH are presented. In the thermal decomposition of azo compounds, the system comprising substrate, silane, and azo-initiator (ACCN) mixed in aqueous medium at 100 °C worked well for both hydrophilic and hydrophobic substrates, with the only variation that the amphiphilic thiol HOCH2CH3SH was also needed in the case of the watersoluble compounds. Dioxygen initiation is shown to afford excellent yields of hydrosilylated products derived from substrates bearing C-C triple bonds and moderate to low yields of hydrosilylated products derived from C-C double-bonded compounds in water. Photochemical initiation in the absence of a chemical radical precursor other than the silane is also found to be a very efficient and convenient method to induce the hydrosilylation reaction of both C-C double and triple bonds of organic compounds (hydrophilic and hydrophobic substrates) with (Me3Si)3SiH in water. These three alternative radicalbased methodologies studied in water are confronted.
Feeding behavior of Adelomelon ancilla (Ligfoot, 1786): A predatory neogastropod (Gastropoda: Volutidae) in Patagonian benthic communities
Bigatti, Gregorio; Sanchez Antelo, Carlos; Miloslavich, Patricia; Penchaszadeh, Pablo Enrique
Adelomelon ancilla, a volutid commonly found in shallow water in northern Patagonia, is a top predator in the benthic communities of this region. This species presents an anemone (Antholoba achates) epibiosis that may protect it from predators. Adelomelon ancilla captures prey by tightly engulfing it with the foot, and ingests them, generally alive, after narcotizing their muscles. A narcotizing substance, produced by the accessory salivary glands, is released through the proboscis into the prey while the latter is tightly enveloped within the foot, allowing for prey narcotization. In this space, water is not abundant and, therefore, the salivary secretion reaches a high concentration, with a pH of around 10. Analysis of prey obtained in situ indicated that A. ancilla mainly consumes bivalves (88.9%), gastropods (9.5%) and, rarely, sea urchins (1.6%). Ingestion of the prey usually occurs while the predator is buried in the substrate, and may last for several hours. The anatomy of the alimentary system and the pH of various organs involved in prey capture and digestion are presented along with a comparison with feeding mechanisms among other species of Volutidae.
Influence of hydraulic conditions over dunes on the distribution of the benthic macroinvertebrates in a large sand bed river
Amsler, Mario Luis; Blettler, Martin Cesar Maria; Ezcurra, Ines Delia
This study aims to relate the flow structure over mobile dunes recorded on the channel bed of the Paraná River (Argentina) with the spatial distribution of the benthic macroinvertebrates. The following main conclusions have been obtained: (1) the dunes found in the active channel could be considered as hydraulic biotopes at a mesohabitat scale: the bed forms in the thalweg region are subjected to higher shear stresses with low benthic densities; (2) differences in benthic densities were also recorded at within-dunes microhabitat scales: the largest densities were found in the dune troughs where small bed shear stresses occur and minimum densities on the low stoss side of dunes where turbulent agitation near the bottom strongly disturb the bed particles; (3) superimposed dunes on larger dunes may be considered as another microhabitat of still smaller dimensions. Summarizing, multiscale approaches are needed if a comprehensive understanding linking hydrodynamics and morphodynamics processes with benthic ecology is intended.
