3,725 research outputs found

    Thermodynamics from a scaling Hamiltonian

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    There are problems with defining the thermodynamic limit of systems with long-range interactions; as a result, the thermodynamic behavior of these types of systems is anomalous. In the present work, we review some concepts from both extensive and nonextensive thermodynamic perspectives. We use a model, whose Hamiltonian takes into account spins ferromagnetically coupled in a chain via a power law that decays at large interparticle distance rr as 1/rα1/r^{\alpha} for α0\alpha\geq0. Here, we review old nonextensive scaling. In addition, we propose a new Hamiltonian scaled by 2(N/2)1α11α2\frac{(N/2)^{1-\alpha}-1}{1-\alpha} that explicitly includes symmetry of the lattice and dependence on the size, NN, of the system. The new approach enabled us to improve upon previous results. A numerical test is conducted through Monte Carlo simulations. In the model, periodic boundary conditions are adopted to eliminate surface effects.Comment: 12 pages, 2 figures, submitted for publication to Phys. Rev.

    Distinct GSDMB protein isoforms and protease cleavage processes differentially control pyroptotic cell death and mitochondrial damage in cancer cells

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    Artículo escrito por un elevado número de autores, solo se referencian el que aparece en primer lugar, el nombre del grupo de colaboración, si lo hubiere, y los autores pertenecientes a la UAMGasdermin (GSDM)-mediated pyroptosis is functionally involved in multiple diseases, but Gasdermin-B (GSDMB) exhibit cell death-dependent and independent activities in several pathologies including cancer. When the GSDMB pore-forming Nterminal domain is released by Granzyme-A cleavage, it provokes cancer cell death, but uncleaved GSDMB promotes multiple pro-tumoral effects (invasion, metastasis, and drug resistance). To uncover the mechanisms of GSDMB pyroptosis, here we determined the GSDMB regions essential for cell death and described for the first time a differential role of the four translated GSDMB isoforms (GSDMB1-4, that differ in the alternative usage of exons 6-7) in this process. Accordingly, we here prove that exon 6 translation is essential for GSDMB mediated pyroptosis, and therefore, GSDMB isoforms lacking this exon (GSDMB1-2) cannot provoke cancer cell death. Consistently, in breast carcinomas the expression of GSDMB2, and not exon 6-containing variants (GSDMB3-4), associates with unfavourable clinical-pathological parameters. Mechanistically, we show that GSDMB N-terminal constructs containing exon-6 provoke cell membrane lysis and a concomitant mitochondrial damage. Moreover, we have identified specific residues within exon 6 and other regions of the N-terminal domain that are important for GSDMBtriggered cell death as well as for mitochondrial impairment. Additionally, we demonstrated that GSDMB cleavage by specific proteases (Granzyme-A, Neutrophil Elastase and caspases) have different effects on pyroptosis regulation. Thus, immunocytederived Granzyme-A can cleave all GSDMB isoforms, but in only those containing exon 6, this processing results in pyroptosis induction. By contrast, the cleavage of GSDMB isoforms by Neutrophil Elastase or caspases produces short N-terminal fragments with no cytotoxic activity, thus suggesting that these proteases act as inhibitory mechanisms of pyroptosis. Summarizing, our results have important implications for understanding the complex roles of GSDMB isoforms in cancer or other pathologies and for the future design of GSDMB-targeted therapie

    Ácidos graxos poli-insaturados na regulação das concentrações séricas de triglicerídeos e ácidos graxos não esterificados em três gerações de ratos wistar.

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    O objetivo deste estudo foi avaliar o efeito de dietas contendo AGPIs ômega-3 e ômega-6 nas concentrações séricas de ácidos graxos não esterificados (AGNE) e triglicerídeos (TG), no período pré e pós-parto de ratas Wistar, ao longo de três gerações

    Bubble concentration on spheres for supercritical elliptic problems

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    We consider the supercritical Lane-Emden problem (P_\eps)\qquad -\Delta v= |v|^{p_\eps-1} v \ \hbox{in}\ \mathcal{A} ,\quad u=0\ \hbox{on}\ \partial\mathcal{A} where A\mathcal A is an annulus in \rr^{2m}, m2m\ge2 and p_\eps={(m+1)+2\over(m+1)-2}-\eps, \eps>0. We prove the existence of positive and sign changing solutions of (P_\eps) concentrating and blowing-up, as \eps\to0, on (m1)(m-1)-dimensional spheres. Using a reduction method (see Ruf-Srikanth (2010) J. Eur. Math. Soc. and Pacella-Srikanth (2012) arXiv:1210.0782)we transform problem (P_\eps) into a nonhomogeneous problem in an annulus \mathcal D\subset \rr^{m+1} which can be solved by a Ljapunov-Schmidt finite dimensional reduction

    3D digital endocast of the early miocene (Colhuehuapian) sipalocyon externa (Metatheria, Sparassodonta)

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    The skull of Sipalocyon externa Ameghino, 1902 (Hathliacynidae) from Sacanana, Chubut, Sarmiento Formation, Colhuehuapian age, is studied (MACN-CH1911).We first record the taxon for this locality, which includes the sparassodonts Acrocyon riggsi Simpson 1930 and a large Borhyaenoidae. The skull is almost complete andwas studied through μCT-scanning, representingthe first digital encephalic cavity cast(c) for Sparassodonta and one of the few known for stem marsupials. Body massof the specimen was estimated based on teeth measurements, following Gordon´s equations (1.7 kg), and skull centroid-size, inspired by Zelditch (2.8 kg). Considering the mean body mass, its encephalization quotient with and without olfactory bulbsc is respectively: 0.32 and 0.30 (Jerison equations) or 0.41 and 0.38 (Eisenberg equations). The estimates for S. externastand between that recorded by Macrini for the marsupials Didelphis virginiana (Kerr, 1792) and Dasyurus hallucatus Gould, 1842 but are larger than those for the stem marsupial Pucadelphys andinus Marshall and De Muizon, 1988.The olfactory bulbc represents 5.88% of the total endocranial volume, which is smaller than the values for P. andinus (11.7 %) and other marsupials (8 %?11 %).The paraflocculusc corresponds to 2.65 %, representing a large proportionof the endocast. This agrees with a deep subarquate fossa (a primitive condition for Metatheria).Vascular organization is largely conservative in this species. Similar to other sparassodonts, the major venous drainage from the endocranium was through the cerebrospinal system instead of jugular vein.In addition, we detected for the first time in this group an accessory transverse sinus enclosed by cranial bone.Fil: Gaillard, Charlene. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Provincia de Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Universidad Nacional de Cuyo. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales; ArgentinaFil: Tarquini, Sergio Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Universidad Nacional de La Rioja. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Universidad Nacional de Catamarca. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Secretaría de Industria y Minería. Servicio Geológico Minero Argentino. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Provincia de La Rioja. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja; ArgentinaFil: Hernández del Pino, Santiago Ezequiel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Provincia de Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Universidad Nacional de Cuyo. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales; ArgentinaFil: Ladeveze, S.. Universite de Paris. Museum National D´historie Naturelle; FranciaFil: Forasiepi, Analia Marta. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Provincia de Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Universidad Nacional de Cuyo. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales; ArgentinaReunión de Comunicaciones de la Asociación Paleontológica ArgentinaLa PlataArgentinaAsociación Paleontológica ArgentinaUniversidad Nacional de La Plata. Facultad de Ciencias Naturales y MuseoFundación Museo de La Plata “Francisco Pascasio Moreno

    NGC 6705 a young α\alpha-enhanced Open Cluster from OCCASO data

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    The stellar [α\alpha/Fe] abundance is sometimes used as a proxy for stellar age, following standard chemical evolution models for the Galaxy, as seen by different observational results. In this work we show that the Open Cluster NGC6705/M11 has a significant α\alpha-enhancement [α\alpha/Fe]>0.1>0.1 dex, despite its young age (\sim300 Myr), challenging the current paradigm. We use high resolution (R>65,000>65,000) high signal-to-noise (\sim70) spectra of 8 Red Clump stars, acquired within the OCCASO survey. We determine very accurate chemical abundances of several α\alpha elements, using an equivalent width methodology (Si, Ca and Ti), and spectral synthesis fits (Mg and O). We obtain [Si/Fe]=0.13±0.050.13\pm0.05, [Mg/Fe]=0.14±0.070.14\pm0.07, [O/Fe]=0.17±0.070.17\pm0.07, [Ca/Fe]=0.06±0.050.06\pm0.05 and [Ti/Fe]=0.03±0.030.03\pm0.03. Our results place these cluster within the group of young [α\alpha/Fe]-enhanced field stars recently found by several authors in the literature. The ages of our stars have an uncertainty of around 50 Myr, much more precise than for field stars. By integrating the cluster's orbit in several non-axisymmetric Galactic potentials, we establish the M11's most likely birth radius to lie between 6.8-7.5 kpc from the Galactic center, not far from its current position. With the robust Open Cluster age scale, our results prove that a moderate [α\alpha/Fe]-enhancement is no guarantee for a star to be old, and that not all α\alpha-enhanced stars can be explained with an evolved blue straggler scenario. Based on our orbit calculations, we further argue against a Galactic bar origin of M11.Comment: 10 pages, 6 figures, accepted in A&

    Sign-changing tower of bubbles for a sinh-Poisson equation with asymmetric exponents

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    Motivated by the statistical mechanics description of stationary 2D-turbulence, for a sinh-Poisson type equation with asymmetric nonlinearity, we construct a concentrating solution sequence in the form of a tower of singular Liouville bubbles, each of which has a different degeneracy exponent. The asymmetry parameter γ(0,1]\gamma\in(0,1] corresponds to the ratio between the intensity of the negatively rotating vortices and the intensity of the positively rotating vortices. Our solutions correspond to a superposition of highly concentrated vortex configurations of alternating orientation; they extend in a nontrivial way some known results for γ=1\gamma=1. Thus, by analyzing the case γ1\gamma\neq1 we emphasize specific properties of the physically relevant parameter γ\gamma in the vortex concentration phenomena
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