1,592 research outputs found

    Path Integral Approach to Strongly Nonlinear Composite

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    We study strongly nonlinear disordered media using a functional method. We solve exactly the problem of a nonlinear impurity in a linear host and we obtain a Bruggeman-like formula for the effective nonlinear susceptibility. This formula reduces to the usual Bruggeman effective medium approximation in the linear case and has the following features: (i) It reproduces the weak contrast expansion to the second order and (ii) the effective medium exponent near the percolation threshold are s=1s=1, t=1+κt=1+\kappa, where κ\kappa is the nonlinearity exponent. Finally, we give analytical expressions for previously numerically calculated quantities.Comment: 4 pages, 1 figure, to appear in Phys. Rev.

    Human Mobility in Large Cities as a Proxy for Crime

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    We investigate at the subscale of the neighborhoods of a highly populated city the incidence of property crimes in terms of both the resident and the floating population. Our results show that a relevant allometric relation could only be observed between property crimes and floating population. More precisely, the evidence of a superlinear behavior indicates that a disproportional number of property crimes occurs in regions where an increased flow of people takes place in the city. For comparison, we also found that the number of crimes of peace disturbance only correlates well, and in a superlinear fashion too, with the resident population. Our study raises the interesting possibility that the superlinearity observed in previous studies [Bettencourt et al., Proc. Natl. Acad. Sci. USA 104, 7301 (2007) and Melo et al., Sci. Rep. 4, 6239 (2014)] for homicides versus population at the city scale could have its origin in the fact that the floating population, and not the resident one, should be taken as the relevant variable determining the intrinsic microdynamical behavior of the system.Comment: 17 pages, 8 Figure

    Síndrome de Birt-Hogg-Dubé

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    A 45-year-old woman with a history of renal carcinoma was observed for facial, cervical and truncal flesh-colored papules. Relatives had similar skin findings and a brother had repeated episodes of pneumothorax. The computerized tomography scan revealed multiple cysts on both lungs. A skin biopsy revealed a perifollicular fibroma. The clinical diagnosis of Birt-Hogg-Dubé syndrome (BHDS) was corroborated by identification of a novel frameshift c.573delGAinsT (p.G191fsX31) mutation in heterozygosity on exon 6 of the folliculin gene. The presence of multiple and typical benign hair follicle tumors highlights the role of the dermatologist in the diagnosis of this rare genodermatosis that is associated with an increased risk of renal cell cancer and pulmonary cysts, warranting personal and familial follow-up and counseling

    Intraepidermal Epidermotropic Metastatic Melanoma: a Clinical and Histopathological Mimicker of Melanoma in Situ Occurring in Multiplicity

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    The distinction between primary melanoma and melanoma metastatic to the skin has major prognostic implications. We report a case of a 67-year-old male with a diagnosis of a superficial spreading melanoma (stage IB) rendered 6 years earlier who presented clinically with an atypical nevus on his left thigh. Histopathological examination showed an intraepidermal melanocytic proliferation that was interpreted as melanoma in situ. Subsequently, 45 additional pigmented macules appeared in crops over a 9-month period. Clinically and dermoscopically, these lesions were extremely polymorphic. Histopathological findings were compatible with melanoma in situ, as each lesion consisted of a wholly intraepidermal proliferation of markedly atypical melanocytes arranged singly and in nests. A complete gastrointestinal study showed multiple pigmented metastatic lesions throughout the stomach and small bowel, which supported a diagnosis of metastatic melanoma with gastrointestinal and epidermotropic skin involvement. Monosomy of chromosome 9 and a BRAF V600E mutation were detected in the primary tumor sample and in macro-dissected secondary lesions. No CDKN2A or CDK4 germline mutations were found. Intraepidermal epidermotropic metastases of melanoma have been rarely described in literature. In this case, histopathology alone was insufficient to distinguish metastatic melanoma from multiple in situ melanomas. The recognition of epidermotropic metastases should be based on the correlation between clinical, dermoscopic, histopathological and molecular findings

    APPLICATIONS OF VORONOI AND DELAUNAY DIAGRAMS IN THE SOLUTION OF THE GEODETIC BOUNDARY VALUE PROBLEM

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    Voronoi and Delaunay structures are presented as discretization tools to be used innumerical surface integration aiming the computation of geodetic problemssolutions, when under the integral there is a non-analytical function (e. g., gravityanomaly and height). In the Voronoi approach, the target area is partitioned intopolygons which contain the observed point and no interpolation is necessary, onlythe original data is used. In the Delaunay approach, the observed points are verticesof triangular cells and the value for a cell is interpolated for its barycenter. If theamount and distribution of the observed points are adequate, gridding operation isnot required and the numerical surface integration is carried out by point-wise. Evenwhen the amount and distribution of the observed points are not enough, thestructures of Voronoi and Delaunay can combine grid with observed points in orderto preserve the integrity of the original information. Both schemes are applied to thecomputation of the Stokes’ integral, the terrain correction, the indirect effect and thegradient of the gravity anomaly, in the State of Rio de Janeiro, Brazil area

    Detecção de Cucumber mosaic virus em alface no estado do Pará.

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    A alface (Lactuca sativa L.) é uma planta anual, originária de clima temperado, pertencente à família Asteracea, e certamente uma das hortaliças mais populares e consumidas no Brasil e no mundo. Diversas viroses podem causar danos à cultura da alface. O objetivo deste trabalho foi detectar a presença do Cucumber mosaic virus (CMV) na cultura da alface, utilizando o teste RT-PCR. Foram coletadas 50 amostras de alface aparentemente sem sintomas característicos de viroses no município de Ananindeua-PA e na horta da UFRA campus Belém-PA. O ácido nucléico total foi extraído a partir de folhas de alface. Para a detecção do CMV por meio do RT-PCR utilizou-se um par de iniciadores denominados CMV-CPR e CMV-CPF que permitem a amplificação do fragmento de cerca de 700 pb do DNA do gene da capa proteica. O CMV foi detectado em três amostras analisadas. Este foi o primeiro relato de CMV em alface no estado do Pará

    Ictiólogos de la Argentina: Elvira Mariana Siccardi.

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    En esta serie se mencionan a todos aquellos que, a través de sus pequeños o grandes aportes, contribuyeron a la consolidación de la disciplina en nuestro país. El plan general de esta contribución consiste en la elaboración de fichas individuales que contengan una lista de trabajos de los diferentes autores, acompañadas por bibliografía de referencia y, cuando ello fuera posible, por imágenes personales y material adicional. Se tratará de guardar un orden cronológico, pero esto no es excluyente, ya que priorizaremos las sucesivas ediciones al material disponible. Este es otro camino para rescatar y revalorizar a quienes en diversos contextos históricos sentaron las bases de lo que hoy es la ictiología nacional. Considero que este es el comienzo de una obra de mayor magnitud en la que se logre describir una parte importante de la historia de las ciencias naturales de la República Argentina

    Borderline CD30+ Cutaneous Lymphoproliferative Disorder: Report of a Case with Expression of Cytotoxic Markers and Response to Clarithromycin

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    CD30+ cutaneous lymphoproliferative disorders (CLPDs) are usually characterized by a benign clinical course. The prognostic value of cytotoxic markers in these lymphomas has not been evaluated in large series. We describe a case of borderline CD30+ CLPD with cytotoxic phenotype, presenting in a 22-year-old male patient as an ulcer on the forearm. He reported having had similar ulcers on the buttock and thigh that spontaneously regressed over the course of 1 year. The lesion resolved with a single course of clarithromycin; a subsequent lesion, too, responded to clarithromycin, and no recurrences or systemic involvement have been documented in the 9-month follow-up. A conservative approach in the management of CD30+ CLPD is recommended. We believe that the anti-inflammatory and apoptotic effects of clarithromycin on T cells may have hastened the remission process
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