1,288 research outputs found

    Exact finite-size scaling with corrections in the two-dimensional Ising model with special boundary conditions

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    The two-dimensional Ising model with Brascamp-Kunz boundary conditions has a partition function more amenable to analysis than its counterpart on a torus. This fact is exploited to exactly determine the full finite-size scaling behaviour of the Fisher zeroes of the model. Moreover, exact results are also determined for the scaling of the specific heat at criticality, for the specific-heat peak and for the pseudocritical points. All corrections to scaling are found to be analytic and the shift exponent λ\lambda does not coincide with the inverse of the correlation length exponent 1/ν1/\nu.Comment: 3 pages, LaTeX, No figures, Lattice2001(spin

    Wave Pressures and Loads on a Small Scale Model of the Svåheia SSG Pilot Project

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    The paper reports on 2D small scale experiments conducted to investigate wave loadings acting on a pilot project of device for the conversion of wave energy into electricity. The conversion concept is based on the overtopping principle and the structure is worldwide known with the acronym SSG. The hydraulic model tests have been carried out at the LInC laboratory of the University of Naples Federico II using random waves. Results indicate wave overtopping is able to cause a sudden inversion of vertical force under wave crest, so that it is alternatively upward and downward directed over a short time interval. It is also shown that two calculation methods widely employed in the Japanese design practice of vertical face breakwaters, could be used to achieve safe estimates of the hydrodynamic loadings

    Protein phosphatase 2A promotes hepatocellular carcinogenesis in the diethylnitrosamine mouse model through inhibition of p53

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    Hepatocellular carcinoma (HCC) is one of the most common cancers worldwide. Most HCCs develop in cirrhotic livers. Alcoholic liver disease, chronic hepatitis B and chronic hepatitis C are the most common underlying liver diseases. Hepatitis C virus (HCV)-specific mechanisms that contribute to HCC are presently unknown. Transgenic expression of HCV proteins in the mouse liver induces an overexpression of the protein phosphatase 2A catalytic subunit (PP2Ac). We have previously reported that HCV-induced PP2Ac overexpression modulates histone methylation and acetylation and inhibits DNA damage repair. In this study, we analyze tumor formation and gene expression using HCV transgenic mice that overexpress PP2Ac and liver tissues from patients with HCC. We demonstrate that PP2Ac overexpression interferes with p53-induced apoptosis. Injection of the carcinogen, diethylnitrosamine, induced significantly more and larger liver tumors in HCV transgenic mice that overexpress PP2Ac compared with control mice. In human liver biopsies from patients with HCC, PP2Ac expression was significantly higher in HCC tissue compared with non-tumorous liver tissue from the same patients. Our findings demonstrate an important role of PP2Ac overexpression in liver carcinogenesis and provide insights into the molecular pathogenesis of HCV-induced HC

    The dynamic exponent of the Ising model on negatively curved surfaces

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    We investigate the dynamic critical exponent of the two-dimensional Ising model defined on a curved surface with constant negative curvature. By using the short-time relaxation method, we find a quantitative alteration of the dynamic exponent from the known value for the planar Ising model. This phenomenon is attributed to the fact that the Ising lattices embedded on negatively curved surfaces act as ones in infinite dimensions, thus yielding the dynamic exponent deduced from mean field theory. We further demonstrate that the static critical exponent for the correlation length exhibits the mean field exponent, which agrees with the existing results obtained from canonical Monte Carlo simulations.Comment: 14 pages, 3 figures. to appear in J. Stat. Mec

    Análisis de la reestructuración productiva del sector industrial en Ensenada y Berisso

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    Este capítulo es un aporte al objetivo general del proyecto REDES de identificar patrones de localización industrial de las unidades productivas industriales, teniendo en cuenta la infraestructura de los ejes de circulación que influyen directamente en la reestructuración urbana, y en la localización de actividades diversas como son las comerciales, residenciales o de servicios. Se centra en la identificación de los principales componentes de la reestructuración industrial a escala nacional, el análisis de la misma en Berisso y Ensenada y una descripción particularizada del sector pequeña y mediana empresa (pyme) industrial. Incluye una caracterización de Berisso y Ensenada en el marco de la Región Metropolitana de Buenos Aires - La Plata y del Gran La Plata en particular y la problemática de esta inclusión.Centro Interdisciplinario de Estudios ComplejosInstituto de Investigaciones en Humanidades y Ciencias Sociale

    A multicenter study on the diagnostic significance of a single cerebrospinal fluid IgG band

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    The analysis of paired cerebrospinal fluid (CSF) and serum samples with isolectric focusing (IEF) can yield different patterns which can be of aid in the differential diagnosis of central nervous system (CNS) disorders. Rarely, a single CSF-restricted IgG band, which is not included within these patterns, can be detected in association with inflammatory disorders, multiple sclerosis (MS) above all. However, the diagnostic meaning of this abnormality is still uncertain. The main aim of our multicenter study was to establish the frequency and disease associations of single CSF IgG bands. Differences in the CSF profiles between MS and other diseases, and the follow-up patterns were also evaluated. Medical records of patients who underwent CSF analysis, which included IEF, over a 11.5-year period were retrospectively scrutinized at the participating centers, which used similar IEF techniques. One hundred and fifty-one of 9422 CSF reports (1.6%) showed single CSF-restricted IgG bands. Of the 129 patients with a definite diagnosis, 58.2% had CNS inflammatory-demyelinating diseases (the most frequent being MS: 21.7%), 6.2% tumours, 5.4% inflammatory peripheral nervous system diseases and 30.2% miscellaneous diseases. At follow-up, 3 out of the 10 patients with a repeated CSF analysis had developed an oligoclonal band pattern. Our findings indicate that single CSF IgG bands tend to associate with diseases characterized by the involvement of intrathecal humoral immune responses, and strongly support the notion that this abnormality should be regularly reported, thus alerting clinicians of possible inflammatory disorders of the CNS

    VEGF dose regulates vascular stabilization through Semaphorin3A and the Neuropilin-1+ monocyte/TGF-β1 paracrine axis

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    VEGF is widely investigated for therapeutic angiogenesis, but while short-term delivery is desirable for safety, it is insufficient for new vessel persistence, jeopardizing efficacy. Here, we investigated whether and how VEGF dose regulates nascent vessel stabilization, to identify novel therapeutic targets. Monoclonal populations of transduced myoblasts were used to homogeneously express specific VEGF doses in SCID mouse muscles. VEGF was abrogated after 10 and 17 days by Aflibercept treatment. Vascular stabilization was fastest with low VEGF, but delayed or prevented by higher doses, without affecting pericyte coverage. Rather, VEGF dose-dependently inhibited endothelial Semaphorin3A expression, thereby impairing recruitment of Neuropilin-1-expressing monocytes (NEM), TGF-β1 production and endothelial SMAD2/3 activation. TGF-β1 further initiated a feedback loop stimulating endothelial Semaphorin3A expression, thereby amplifying the stabilizing signals. Blocking experiments showed that NEM recruitment required endogenous Semaphorin3A and that TGF-β1 was necessary to start the Semaphorin3A/NEM axis. Conversely, Semaphorin3A treatment promoted NEM recruitment and vessel stabilization despite high VEGF doses or transient adenoviral delivery. Therefore, VEGF inhibits the endothelial Semaphorin3A/NEM/TGF-β1 paracrine axis and Semaphorin3A treatment accelerates stabilization of VEGF-induced angiogenesis

    Planck intermediate results. XLI. A map of lensing-induced B-modes

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    The secondary cosmic microwave background (CMB) BB-modes stem from the post-decoupling distortion of the polarization EE-modes due to the gravitational lensing effect of large-scale structures. These lensing-induced BB-modes constitute both a valuable probe of the dark matter distribution and an important contaminant for the extraction of the primary CMB BB-modes from inflation. Planck provides accurate nearly all-sky measurements of both the polarization EE-modes and the integrated mass distribution via the reconstruction of the CMB lensing potential. By combining these two data products, we have produced an all-sky template map of the lensing-induced BB-modes using a real-space algorithm that minimizes the impact of sky masks. The cross-correlation of this template with an observed (primordial and secondary) BB-mode map can be used to measure the lensing BB-mode power spectrum at multipoles up to 20002000. In particular, when cross-correlating with the BB-mode contribution directly derived from the Planck polarization maps, we obtain lensing-induced BB-mode power spectrum measurement at a significance level of 12σ12\,\sigma, which agrees with the theoretical expectation derived from the Planck best-fit Λ\LambdaCDM model. This unique nearly all-sky secondary BB-mode template, which includes the lensing-induced information from intermediate to small (10100010\lesssim \ell\lesssim 1000) angular scales, is delivered as part of the Planck 2015 public data release. It will be particularly useful for experiments searching for primordial BB-modes, such as BICEP2/Keck Array or LiteBIRD, since it will enable an estimate to be made of the lensing-induced contribution to the measured total CMB BB-modes.Comment: 20 pages, 12 figures; Accepted for publication in A&A; The B-mode map is part of the PR2-2015 Cosmology Products; available as Lensing Products in the Planck Legacy Archive http://pla.esac.esa.int/pla/#cosmology; and described in the 'Explanatory Supplement' https://wiki.cosmos.esa.int/planckpla2015/index.php/Specially_processed_maps#2015_Lensing-induced_B-mode_ma

    Planck intermediate results. XXIX. All-sky dust modelling with Planck, IRAS, and WISE observations

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    We present all-sky modelling of the high resolution Planck, IRAS, and WISE infrared (IR) observations using the physical dust model presented by Draine and Li in 2007 (DL). We study the performance and results of this model, and discuss implications for future dust modelling. The present work extends the DL dust modelling carried out on nearby galaxies using Herschel and Spitzer data to Galactic dust emission. We employ the DL dust model to generate maps of the dust mass surface density, the optical extinction Av, and the starlight intensity parametrized by Umin. The DL model reproduces the observed spectral energy distribution (SED) satisfactorily over most of the sky, with small deviations in the inner Galactic disk and in low ecliptic latitude areas. We compare the DL optical extinction Av for the diffuse interstellar medium with optical estimates for 2 10^5 quasi-stellar objects (QSOs) observed in the Sloan digital sky survey. The DL Av estimates are larger than those determined towards QSOs by a factor of about 2, which depends on Umin. The DL fitting parameter Umin, effectively determined by the wavelength where the SED peaks, appears to trace variations in the far-IR opacity of the dust grains per unit Av, and not only in the starlight intensity. To circumvent the model deficiency, we propose an empirical renormalization of the DL Av estimate, dependent of Umin, which compensates for the systematic differences found with QSO observations. This renormalization also brings into agreement the DL Av estimates with those derived for molecular clouds from the near-IR colours of stars in the 2 micron all sky survey. The DL model and the QSOs data are used to compress the spectral information in the Planck and IRAS observations for the diffuse ISM to a family of 20 SEDs normalized per Av, parameterized by Umin, which may be used to test and empirically calibrate dust models.Comment: Final version that has appeared in A&
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