Ciencia y Tecnología

Domain wall interactions due to vacuum Dirac field fluctuations in 2+1 dimensions

CONICET Digital -

Domain wall interactions due to vacuum Dirac field fluctuations in 2+1 dimensions Fosco, Cesar Daniel; Mazzitelli, Francisco Diego We evaluate quantum effects due to a two-component Dirac field in 2+1 spacetime dimensions, coupled to domain-wall-like defects with a smooth shape. We show that these effects induce nontrivial contributions to the (shape-dependent) energy of the domain walls. For a single defect, we study the divergences in the corresponding self-energy, and also consider the role of the massless zero mode - corresponding to the Callan-Harvey mechanism - by coupling the Dirac field to an external gauge field. For two defects, we show that the Dirac field induces a nontrivial, Casimir-like effect between them, and we provide an exact expression for that interaction in the case of two straight-line parallel defects. As is the case for the Casimir interaction energy, the result is finite and unambiguous.

RC 2016 - Proceso de admisión

ANPCyT -

El Fondo para la Investigación Científica y Tecnológica (FONCyT) anuncia los resultados del proceso de admisión de la convocatoria RC 2016 mediante Disposición Administrativa del FONCyT N° 26/16 con fecha 13/07/2016.

PICT 2015 Categoría V - Proceso de adjudicación

ANPCyT -

El Fondo para la Investigación Científica y Tecnológica (FONCYT) anuncia los resultados del proceso de adjudicación para la convocatoria PICT 2015 Categoría V Proyectos Interdisciplinarios de Impacto Internacional mediante Resolución de Agencia N°360/16 con fecha 11/07/2016.

Highly crystalline LiCuXFe1-XPO4 nanoparticles synthesized by high temperature thermal decomposition: A morphological and electrical transport study

CONICET Digital -

Highly crystalline LiCuXFe1-XPO4 nanoparticles synthesized by high temperature thermal decomposition: A morphological and electrical transport study Martinez, Pablo Sergio; Ruiz, Fabricio Carlos; Curiale, Carlos Javier; Vasquez Mansilla, Marcelo; Zysler, Roberto Daniel; Dada, L.; Moreno, Mario Sergio Jesus; Rodriguez, Luis Miguel; Fregenal, Daniel Eduardo; Bernardi, Guillermo Carlos; Lima, Enio Junior In this work, we report the morphological and electrical characterization of highly crystalline LiCuxFe1-xPO4 nanoparticles synthesized via the high-temperature (380 °C) thermal decomposition of organometallic precursors. The mean diameter of the studied nanoparticles was 30–40 nm. The Cu/Fe relations of 0, 0.001 and 0.042 for the three studied samples were obtained via particle-induced x-ray emission spectroscopy. Crystallographic and morphological studies were performed using x-ray diffraction, transmission electron microscopy and high-resolution transmission electron microscopy techniques. We investigated the effects of incorporating copper on the electric transport properties of this highly crystalline nanometric system using impedance spectroscopy and DC transport techniques. The experimental evidence allowed us to conclude that in the frequency range f   <  1 kHz the transport is dominated by the diffusion of Li and the presence of Cu atoms in the systems hinders this transport mechanism, despite the high crystallinity of the system.

A new species of arboreal rat, genus Oecomys (Rodentia, Cricetidae) from Chaco

CONICET Digital -

A new species of arboreal rat, genus Oecomys (Rodentia, Cricetidae) from Chaco Pardiñas, Ulises Francisco J.; Teta, Pablo Vicente; Jorge Salazar Bravo; Myers, Phil; Galliari, Carlos Alberto A new species of rodent is added to the highly diverse genus Oecomys (Cricetidae, Sigmodontinae, Oryzomyini)based on specimens collected in the Argentinian provinces of Chaco and Formosa. The new species ischaracterized by a derived carotid circulatory pattern, a feature shared with O. concolor, O. mamorae, and O. sydandersoni. A unique combination of morphological, morphometric, and molecular characters, however,provides unambiguous evidence of its validity as a separate entity. Individuals of the new species are larger thanother representatives of Oecomys, and their skulls have wide and cuneate interorbital regions with well-developedsupraorbital shelves, long incisive foramina, long palates, absent alisphenoid struts, and broad Eustachian tubes.This new Oecomys appears to be endemic to the Humid Chaco, an ecoregion listed as Vulnerable due to thehuman impact. Preliminary observations suggest that several specimens from Eastern Paraguay and the BrazilianPantanal could also be assigned to the new species described herein.; Una nueva especie es adicionada al altamente diverso género de roedores Oecomys (Cricetidae, Sigmodontinae, Oryzomyini), sobre la base de especímenes coleccionados en las provincias Argentinas de Chaco y Formosa. La nueva especie se caracteriza por un patrón de circulación carotídea derivado, un rasgo compartido con O. concolor, O. mamorae y O. sydandersoni. Sin embargo, la combinación única de caracteres morfológicos, morfométricos y moleculares provee evidencia inequívoca sobre su validez como una entidad separada. Individuos de la nueva especie son de mayor tamaño en comparación con otros Oecomys y sus cráneos tienen una región interorbitaria ancha y acuñada con plataformas supraorbitarias bien desarrolladas, forámenes incisivos largos, paladares largos, ausencia de las barras alisfenoideas y tubos de Eustaquio anchos. Este nuevo Oecomys parece ser endémico del Chaco Húmedo, una ecorregión considerada como Vulnerable debido al impacto antrópico. Observaciones preliminares sugieren que varios especímenes de Paraguay Oriental y del Pantanal Brasilero podrían también ser asignados a la nueva especie aquí descrita.

The metastasis inducer CCN1 (CYR61) activates the fatty acid synthase (FASN)-driven lipogenic phenotype in breast cancer cells

CONICET Digital -

The metastasis inducer CCN1 (CYR61) activates the fatty acid synthase (FASN)-driven lipogenic phenotype in breast cancer cells Menendez, Javier A.; Vellón, Luciano; Espinoza, Ingrid; Lupu, Ruth The angiogenic inducer CCN1 (Cysteine-rich 61, CYR61) is differentially activated in metastatic breast carcinomas. However, little is known about the precise mechanisms that underlie the pro-metastatic actions of CCN1. Here, we investigated the impact of CCN1 expression on fatty acid synthase (FASN), a metabolic oncogene thought to provide cancer cells with proliferative and survival advantages. Forced expression of CCN1 in MCF-7 cells robustly up-regulated FASN protein expression and also significantly increased FASN gene promoter activity 2- to 3-fold, whereas deletion of the sterol response element-binding protein (SREBP) binding site in the FASN promoter completely abrogated CCN1-driven transcriptional activation. Pharmacological blockade of MAPK or PI-3´K activation similarly prevented the ability of CCN1 to induce FASN gene activation. Pharmacological inhibition of FASN activity with the mycotoxin cerulenin or the small compound C75 reversed CCN1-induced acquisition of estrogen independence and resistance to hormone therapies such as tamoxifen and fulvestrant in anchorage-independent growth assays. This study uncovers FASNdependent endogenous lipogenesis as a new mechanism controlling the metastatic phenotype promoted by CCN1. Because estrogen independence and progression to a metastatic phenotype are hallmarks of therapeutic resistance and mortality in breast cancer, this previously unrecognized CCN1-driven lipogenic phenotype represents a novel metabolic target to clinically manage metastatic disease progression.

Composition dependence of the Néel temperature and the entropy of the magnetic transition in the fcc phase of Fe-Mn and Fe-Mn-Co alloys

CONICET Digital -

Composition dependence of the Néel temperature and the entropy of the magnetic transition in the fcc phase of Fe-Mn and Fe-Mn-Co alloys la Roca, Paulo Matías; Marinelli, P.; Baruj, Alberto Leonardo; Sade Lichtmann, Marcos Leonel; Fernandez Guillermet, Armando Jorge A key feature of the fcc-to-hcp martensitic transformation (MT) in Fe-Mn based alloys is that the fcc structure is strongly stabilized by a paramagnetic-to-antiferromagnetic ordering reaction, which partially or completely inhibits the MT. In order to treat this phenomenon in thermodynamic terms it is necessary to account for the composition dependence of the Néel temperature (TN) of the alloy and the entropy change (ΔSmg) associated to the loss of the antiferromagnetic ordering. In the present work the composition dependence of these properties in Fe-Mn and Fe-Mn-Co alloys have been established by performing systematic measurements of the heat capacity. The current results are critically compared with experimental data from the literature, as well as estimates and correlations based on previous analyses by the present authors. The relevance of the reported data for the understanding of the fcc-to-hcp MT in the Fe-Mn and Fe-Mn-Co alloys is highlighted.

Omisión de cuestión esencial y contrafácticos

CONICET Digital -

Omisión de cuestión esencial y contrafácticos Cucatto, Mariana; Sosa, Toribio Enrique Una cuestión omitida es unacuestión no tratada expresamente peroque debió tratarse de ese modo; y paracorroborar si una cuestión omitida esesencial, debe detectarse al menosla existencia de un contrafáctico: si hipotética e imaginariamente se la hubiera tratado expresamente -que en la realidad no lo fue-, entonces habría podido arribarse a un desenlace diferente -del que en la realidad fue-. SUMARIO: I. Noción de cuestión. II. Detección y ordenamiento de cuestiones. III. Desplazamiento de cuestiones. IV. Desplazamiento y omisión de cuestiones. V. Cuestión de tratamiento expreso omitido como cuestión decidida "por no". VI. Breve caracterización de los contrafácticos. VII. Omisión de cuestión esencial y contrafácticos. VIII. Los contrafácticos en algunos precedentes. IX. Síntesis final.

Peronismo, dictadura y universidades privadas en la Argentina de los años 70

CONICET Digital -

Peronismo, dictadura y universidades privadas en la Argentina de los años 70; Peronism, dictatorship and private universities in Argentina of the 1970s Algañaraz Soria, Victor Hugo A partir del análisis de normativas universitarias, bibliografía especializada y fundamentalmente fuentes documentales y testimoniales, este artículo aborda la trama del sector universitario privado durante el complejo interregno que significaron los años setentas para la historia reciente Argentina. Observaremos que tras el reingreso del peronismo al poder del Estado en 1973, la alta sustentabilidad adquirida por el sector en años anteriores fue puesta en jaque: conflictos estudiantiles, intervenciones políticas y un crecimiento institucional refrenado, fueron algunos de sus rasgos distintivos. En cuanto a la última dictadura militar (1976-1983), abrió una contradictoria etapa de desarrollo para las universidades privadas. Pese a la alternancia de católicos conservadores en el área educativa y al sesgo privatista identificado como un hito del modelo económico implementado, el sector privado resultó contraído en el marco del avasallamiento más brutal del sistema universitario en su conjunto. Sin embargo, algunas universidades católicas resultaron beneficiadas con importantes estímulos económicos.; Drawing from the analysis of university regulations, specialized literature and mainly documentary and testimonial sources, this paper addresses the weft of the private university sector during the complex interregnum that meant the seventies years for Argentina's recent history. We´ll observe that after the reentry of Peronism to power State in 1973, the high sustainability acquired by the sector in previous years was put in check: student conflicts, political interventions and a restrained institutional growth, were some of its distinctive features. Regarding the last military dictatorship (1976-1983), opened a contradictory stage of development for private universities. Despite the alternating of conservative catholics in educative area and privatizing slant identified as a milestone of the implemented economic model, the private sector was contracted under the most brutal subjugation of the university system as a whole. However, some catholic universities were benefited with important economic stimulus.

Páginas

Suscribirse a Facultad de Ciencias Químicas de la Universidad Nacional de Córdoba agregador - Ciencia y Tecnología