2,337 research outputs found

    Effective field approach to the Ising film in a transverse field

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    We study the phase transitions of the spin-1/2 Ising film in a transverse field within the framework of the effective field theory. We evaluate the critical temperature of the film as a function of the exchange interactions, the transverse field and the film thickness. We find that, if the ratio of the surface exchange interactions to the bulk ones R=Js/J is smaller than a critical value Rc, the critical temperature Tc/J of the film is smaller than the bulk critical temperature Tc^B/J and approaches Tc^B/J as R increases further. On the other hand, if R>Rc, Tc/J is larger than both the bulk Tc^B/J and the surface Tc^S/J critical temperatures of the corresponding semi-infinite system, and approaches Tc^S as R increases further.Comment: 16 pages, 5 figures, elsart.cls (included

    A structural connectivity convergence zone in the ventral and anterior temporal lobes: Data-driven evidence from structural imaging

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    The hub-and-spoke model of semantic cognition seeks to reconcile embodied views of a fully distributed semantic network with patient evidence, primarily from semantic dementia, who demonstrate modality-independent conceptual deficits associated with atrophy centred on the ventrolateral anterior temporal lobe. The proponents of this model have recently suggested that the temporal cortex is a graded representational space where concepts become less linked to a specific modality as they are processed farther away from primary and secondary sensory cortices and towards the ventral anterior temporal lobe. To explore whether there is evidence that the connectivity patterns of the temporal lobe converge in its ventral anterior end the current study uses three dimensional Laplacian eigenmapping, a technique that allows visualisation of similarity in a low dimensional space. In this space similarity is encoded in terms of distances between data points. We found that the ventral and anterior temporal lobe is in a unique position of being at the centre of mass of the data points within the connective similarity space. This can be interpreted as the area where the connectivity profiles of all other temporal cortex voxels converge. This study is the first to explicitly investigate the pattern of connectivity and thus provides the missing link in the evidence that the ventral anterior temporal lobe can be considered a multi-modal graded hub

    El Borda, un jardín con valor histórico, artístico y cultural: análisis paisajístico

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    230 páginas. Maestría en Diseño.El presente trabajo de investigación, se aboca al estudio del Jardín Borda, ubicado en la ciudad de Cuernavaca, Morelos. El primer acercamiento aborda el entorno natural y construido en la región en que se inserta dicho jardín, analizando componentes tales como clima, vegetación, hidrología, suelos, fisiografía y topografía e identifica las geoformas que sustentan la expresión del paisaje, a saber, Sierra Alta, Piedemonte y los Valles. Se describe brevemente la problemática urbana del centro histórico, así como las peculiaridades de su traza urbana, el tipo de actividades y los rasgos más significativos que determinan la imagen urbana. Se propone una tipología de los paisajes existentes (paisaje agrícola de temporal, paisaje agrícola de riego y paisaje urbano), para una mejor comprensión de la dinámica del sitio de estudio. Se concibe el jardín como una expresión más de la cultura, por ello se acerca al concepto de jardín, abordándose más adelante las condiciones y características que el Jardín Borda cumple para ser considerado como un jardín con valor histórico, artístico y cultural. Se considera al objeto de estudio como un documento-jardín, para estudiarlo a través de la historia, identificando las vicisitudes, hechos y personajes históricos que se encuentran ligados a los cambios establecidos en el tiempo. En este recorrido se intenta describir las alteraciones que ha sufrido con los cambios de uso, las modas y hábitos de jardinería, y las modificaciones establecidas en sus facturas arquitectónicas y en los componentes mismos del jardín. Finalmente y a partir de la forma básica del paisaje, se realiza el análisis de sus componentes, con la finalidad de conocer el grado de deterioro en que se encuentra y con base en ello, establecer una serie de lineamientos con la finalidad de su mejoramiento

    Analysis of Andean blackberry (Rubus glaucus) production models obtained by means of artificial neural networks exploiting information collected by small-scale growers in Colombia and publicly available meteorological data

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    The Andean blackberry (Rubus glaucus) is an important source of income in hillside regions of Colombia. However, growers have little reliable information on the factors that affect the development and yield of the crop, and therefore there is a dearth of information onhowto effectively manage the crop. Site specific information recorded by small-scale producers of the Andean blackberry on their production systems and soils coupled with publicly available meteorological data was used to develop models of such production systems. Multilayer perceptrons and Self-Organizing Maps were used as computational models in the identification and visualization of the most important variables for modeling the production of Andean blackberry. Artificial neural networks were trained with information from 20 sites in Colombia where the Andean blackberry is cultivated. Multilayer perceptrons predicted with a reasonable degree of accuracy the production response of the crop. The soil depth, the average temperature, external drainage, and the accumulated precipitation of the first month before harvest were critical determinants of productivity. A proxy variable of location was used to describe overall differences in management between farmers groups. The use of this proxy indicated that, even under essentially similar environmental conditions, large differences in production could be assigned to management effects. The information obtained can be used to determine sites that are suitable for Andean blackberry production, and to transfer ofmanagement practices from sites of high productivity to sites with similar environmental conditions which currently have lower levels of productivity

    Design de moda na periferia

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    As periferias brasileiras contam vários grupos organizados e fortemente atuantes dentro do segmento de vestuário e artesanato. Motivados pela dificuldade em obter colocação dentro do mercado formal de trabalho, boa parte da população tem encontrado na atividade informal, uma alternativa viável para sua sobrevivência

    Cartografía imaginaria: límites cognoscitivos del paisaje urbano en Mexicali, B.C.

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    Se propone el concepto de límite cognoscitivo asociado al concepto de lugar como un ingrediente fundamental para el estudio y comprensión del paisaje. Los límites, fronteras, bordes o umbrales, representan una variación de componentes físicos, sicológicos o sociales en un espacio determinado, en nuestro caso, el centro antiguo de Mexicali, pero también significa una variación en el gradiente sensible del sujeto que percibe y valora dichos componentes. Finalmente, se considera que los estudios subjetivos del paisaje urbano son tan importantes y relevantes como los estudios de carácter objetivo, y que ambos enfoques aportan herramientas suficientes para mejorar y conservar las características más relevantes del paisaje urbano en Mexicali

    Molecular analysis of hepatitis B virus "a" determinant in asymptomatic and symptomatic Mexican carriers

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    BACKGROUND: Hepatitis B virus (HBV) is a small DNA-containing virus with 4 genes, C, S, X and P. The S gene codes for the surface antigen (HBsAg), which contains the "a" determinant, the main region for induction of a protective humoral immune response. To compare the genotype and sequence of the "a" determinant between strains isolated from asymptomatic and symptomatic Mexican HBV carriers. RESULTS: 21 asymptomatic (blood donors) and 12 symptomatic (with clinical signs and with >1 year lamivudine treatment) HBV carriers were studied; all patients were positive for the HBsAg in serum. Viral load, genotypes, and subtypes were determined in plasma. A fragment of the S gene including the "a" determinant was PCR amplified and sequenced to determine genotype, subtype and to identify mutations. Mean viral load was 0.7965 × 10(4 )copies/ml in asymptomatic carriers and 2.73 × 10(6 )copies/ml in symptomatic patients. Genotypes H, C, and F were identified in asymptomatic individuals; whereas H was dominant in symptomatic patients. A fragment of 279 bp containing the "a" determinant was amplified from all 33 carriers and sequences aligned with S gene sequences in the GenBank. Mutations identified were Y100N, T126I, Q129H and N146K in the asymptomatic group, and F93I and A128V in the symptomatic group. CONCLUSION: Differences in genotype and in mutations in the "a" determinant were found between strains from asymptomatic and symptomatic HBV Mexican carriers

    Restrictive ID policies: implications for health equity

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    We wish to thank Synod Community Services for their critical work to develop, support, and implement a local government-issued ID in Washtenaw County, MI. We also thank Yousef Rabhi of the Michigan House of Representatives and Janelle Fa'aola of the Washtenaw ID Task Force, Lawrence Kestenbaum of the Washtenaw County Clerk's Office, Sherriff Jerry Clayton of the Washtenaw County Sherriff's Office, and the Washtenaw ID Task Force for their tireless commitment to developing and supporting the successful implementation of the Washtenaw ID. Additionally, we thank Vicenta Vargas and Skye Hillier for their contributions to the Washtenaw ID evaluation. We thank the Curtis Center for Research and Evaluation at the University of Michigan School of Social Work, the National Center for Institutional Diversity at the University of Michigan, and the University of California-Irvine Department of Chicano/Latino Studies and Program in Public Health for their support of the Washtenaw ID community-academic research partnership. Finally, we thank the reviewers for their helpful comments on earlier drafts of this manuscript. (Curtis Center for Research and Evaluation at the University of Michigan School of Social Work; National Center for Institutional Diversity at the University of Michigan; University of California-Irvine Department of Chicano/Latino Studies; Program in Public Health)https://link.springer.com/content/pdf/10.1007/s10903-017-0579-3.pdfPublished versio

    Soluble tumor necrosis factor receptor 1 and 2 predict outcomes in advanced chronic kidney disease : a prospective cohort study

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    Background : Soluble tumor necrosis factor receptors 1 (sTNFR1) and 2 (sTNFR2) have been associated to progression of renal failure, end stage renal disease and mortality in early stages of chronic kidney disease (CKD), mostly in the context of diabetic nephropathy. The predictive value of these markers in advanced stages of CKD irrespective of the specific causes of kidney disease has not yet been defined. In this study, the relationship between sTNFR1 and sTNFR2 and the risk for adverse cardiovascular events (CVE) and all-cause mortality was investigated in a population with CKD stage 4-5, not yet on dialysis, to minimize the confounding by renal function. Patients and methods : In 131 patients, CKD stage 4-5, sTNFR1, sTNFR2 were analysed for their association to a composite endpoint of all-cause mortality or first non-fatal CVE by univariate and multivariate Cox proportional hazards models. In the multivariate models, age, gender, CRP, eGFR and significant comorbidities were included as covariates. Results : During a median follow-up of 33 months, 40 events (30.5%) occurred of which 29 deaths (22.1%) and 11 (8.4%) first non-fatal CVE. In univariate analysis, the hazard ratios (HR) of sTNFR1 and sTNFR2 for negative outcome were 1.49 (95% confidence interval (CI): 1.28-1.75) and 1.13 (95% CI: 1.06-1.20) respectively. After adjustment for clinical covariables (age, CRP, diabetes and a history of cardiovascular disease) both sTNFRs remained independently associated to outcomes (HR: sTNFR1: 1.51, 95% CI: 1.30-1.77; sTNFR2: 1.13, 95% CI: 1.06-1.20). A subanalysis of the non-diabetic patients in the study population confirmed these findings, especially for sTNFR1. Conclusion : sTNFR1 and sTNFR2 are independently associated to all-cause mortality or an increased risk for cardiovascular events in advanced CKD irrespective of the cause of kidney disease
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