1,261 research outputs found

    On the computation of Bernstein–Sato ideals

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    AbstractIn this paper we compare the approach of Briançon and Maisonobe for computing Bernstein–Sato ideals—based on computations in a Poincaré–Birkhoff–Witt algebra—with the readily available method of Oaku and Takayama. We show that it can deal with interesting examples that have proved intractable so far

    Algebraic computation of some intersection D-modules

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    Let XX be a complex analytic manifold, DXD\subset X a locally quasi-homogeneous free divisor, EE an integrable logarithmic connection with respect to DD and LL the local system of the horizontal sections of EE on XDX-D. In this paper we give an algebraic description in terms of EE of the regular holonomic D-module whose de Rham complex is the intersection complex associated with LL. As an application, we perform some effective computations in the case of quasi-homogeneous plane curves.Comment: 18 page

    FGF-2 and anosmin-1 are selectively expressed in different types of multiple sclerosis lesions

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    Multiple sclerosis is a demyelinating disease that affects ~2,000,000 people worldwide. In the advanced stages of the disease, endogenous oligodendrocyte precursors cannot colonize the lesions or differentiate into myelinating oligodendrocytes. During development, both FGF-2 and Anosmin-1 participate in oligodendrocyte precursor cell migration, acting via the FGF receptor 1 (FGFR1). Hence, we performed a histopathological and molecular analysis of these developmental modulators in postmortem tissue blocks from multiple sclerosis patients. Accordingly, we demonstrate that the distribution of FGF-2 and Anosmin-1 varies between the different types of multiple sclerosis lesions: FGF-2 is expressed only within active lesions and in the periplaque of chronic lesions, whereas Anosmin-1 is upregulated within chronic lesions and is totally absent in active lesions. We show that the endogenous oligodendrocyte precursor cells recruited toward chronic-active lesions express FGFR1, possibly in response to the FGF-2 produced by microglial cells in the periplaque. Also in human tissue, FGF-2 is upregulated in perivascular astrocytes in regions of the normal-appearing gray matter, where the integrity of the blood-brain barrier is compromised. In culture, FGF-2 and Anosmin-1 influence adult mouse oligodendrocyte precursor cell migration in the same manner as at embryonic stages, providing an explanation for the histopathological observations: FGF-2 attracts/ enhances its migration, which is hindered by Anosmin-1. We propose that FGF-2 and Anosmin-1 are markers for the histopathological type and the level of inflammation of multiple sclerosis lesions, and that they may serve as novel pharmacogenetic targets to design future therapies that favor effective remyelination and protect the blood-brain barrier. © 2011 the authors.Peer Reviewe

    Maximal multihomogeneity of algebraic hypersurface singularities

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    From the degree zero part of logarithmic vector fields along an algebraic hypersurface singularity we indentify the maximal multihomogeneity of a defining equation in form of a maximal algebraic torus in the embedded automorphism group. We show that all such maximal tori are conjugate and in one-to-one correspondence to maxmimal tori in the degree zero jet of the embedded automorphism group. The result is motivated by Kyoji Saito's characterization of quasihomogeneity for isolated hypersurface singularities and extends its formal version and a result of Hauser and Mueller.Comment: 5 page

    ESTUDIO DEL PERFORMANCE DE LOS GRUPOS ESTRATÉGICOS EN EL SISTEMA DE FRANQUICIA ESPAÑOL

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    La preocupación por considerar la heterogeneidad en los comportamientos empresariales dentro de un sector de actividad, ha sido uno de los principales motivos para la búsqueda e identificación de grupos estratégicos, generando un debate inagotable en el ámbito de la estrategia empresarial. Sin embargo, esta preocupación no se ha limitado a identificar arquetipos o configuraciones empresariales, sino que también se ha extendido al estudio de posibles diferencias en el rendimiento entre los grupos identificados. En el presente trabajo, intentamos dar respuesta a esta doble preocupación y todo ello centrándonos en el ámbito de la franquicia. Para ello, se ha elaborado una base de datos con el total de cadenas franquiciadoras (664) que en el año 2005 operaban en España. Los resultados obtenidos revelan la existencia de cinco grupos estratégicos (tipos de franquiciadores) perfectamente diferenciados, los cuales son descritos a partir de las variables estratégicas que los definen. Igualmente, se demuestra la existencia de diferencias en los resultados inter-grupales a partir de determinados indicadores de desempeño (ingresos, resultados ordinarios y rentabilidad)

    Quasihomogeneity of isolated singularities and logarithmic cohomology

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    We characterize quasihomogeneity of isolated singularities by the injectivity of the map induced by the first differential of the logarithmic differential complex in the top local cohomology supported in the singular point.Comment: 5 page

    Effect of an educational intervention in primary care physicians on the compliance of indicators of good clinical practice in the treatment of type 2 diabetes mellitus [OBTEDIGA project]

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    [Abstract] Aim. To evaluate the effect of an educational intervention among primary care physicians on several indicators of good clinical practice in diabetes care. Methods. Two groups of physicians were randomly assigned to the intervention or control group (IG and CG). Every physician randomly selected two samples of patients from all type 2 diabetic patients aged 40 years and above and diagnosed more than a year ago. Baseline and final information were collected cross-sectionally 12 months apart, in two independent samples of 30 patients per physician. The educational intervention comprised: distribution of educational materials and physicians' specific bench-marking information, an on-line course and three on-site educational workshops on diabetes. External observers collected information directly from the physicians and from the medical records of the patients on personal and family history of disease and on the evolution and treatment of their disease. Baseline information was collected retrospectively in the control group. Results. Intervention group comprised 53 physicians who included a total of 3018 patients in the baseline and final evaluations. CG comprised 50 physicians who included 2868 patients in the same evaluations. Measurement of micro-albuminuria in the last 12 months (OR = 1.6, 95% CI: 1.1–2.4) and foot examination in the last year (OR = 2.0, 95% CI: 1.1–3.6) were the indicators for which greater improvement was found in the IG. No other indicator considered showed statistically significant improvement between groups. Conclusions. The identification of indicators with very low level of compliance and the implementation of a simple intervention in physicians to correct them is effective in improving the quality of care of diabetic patients

    Welfare of horses from Mexico and the United States of America transported for slaughter in Mexico: Fitness profiles for transport and pre-slaughter logistics

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    Every year thousands of horses from Mexico and the United States of America (USA) are transported to slaughter in Mexico, but little is known about their welfare or pre-slaughter logistics. In this study, we recorded the origin, sex, age and condition of horses (121 journeys, 2648 animals) upon arrival to an abattoir in northern Mexico, including transport details. Horse welfare was measured indirectly via individual scores for body condition, coat quality, lameness, ocular and nasal discharge, as well as reactivity to a chute restraint test, all performed shortly after unloading. The average journey duration was 9.69 (±7.6) hours for horses from Mexico and 16.77 (±4.51) hours for horses from the USA (77 % of all journeys). The prevalence of ocular discharge, nasal discharge, skin wounds, lameness and diarrhoea, were 23 %, 12 %, 11 %, 9 %, 1 % (respectively) of all the horses observed, with no significant differences between Mexican and American horses (P = 0.05). During the chute test the American horses were calmer than the Mexican ones (P < 0.001), who were more restless and aggressive (P = 0.001). Likewise, vocalizations in their three variants during the restraint, neigh/whinny (P = 0.018), nicker (P < 0.001), and snort (P = 0.018), were more common in horses from Mexico. In order to help characterize fitness for transport, a two-step cluster analysis was applied using the welfare indicators, suggesting the existence of four clusters (C) evaluated on arrival at the abattoir (from good to very poor fitness): good (profile C4, n = 769, 29.1 %), average (profile C1, n = 799 horses, 30.2 %), poor (profile C3, n = 586, 22.1 %) and very poor (profile C2, n = 494, 18.6 %). In fact, the C4 best welfare group had 0% lame, 0% nasal discharge, 16.4 % ocular discharge, 7.9 % skin wounds. Instead, the C2 poorest welfare group had 45.8 % lame, 61.1 % nasal discharge, 42.8 % ocular discharge, and 19.9 % skin wounds. Results show potential for using nasal discharge, lameness and ocular discharge as key indicators of horse fitness and welfare on abattoir. The study provides detailed scientific data to help establish strategies regarding optimal days of recovery post-transport and fattening for homogenization of weights between animals of different origins, logistic planning, and optimization of logistic resources to minimize the biological cost of long-distance transport
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