5,585 research outputs found

    Galactic Nonlinear Dynamic Model

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    We develop a model for spiral galaxies based on a nonlinear realization of the Newtonian dynamics starting from the momentum and mass conservations in the phase space. The radial solution exhibits a rotation curve in qualitative accordance with the observational data.Comment: 6 pages, 1 figure. Talk given in the 7th Alexander Friedmann International Seminar, June 29 to July 5, 2008, Joao Pessoa, PB, Brazi

    Como calcular o custo de produção de uma silagem.

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    Comparação de diferentes estratégias de programação de irrigação suplementar em milho.

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    Uma das estratégias mais simples, embora pouco precisa, para programar irrigações é utilizar a média da evapotranspiração de referência (ETo), de uma série histórica de dados climáticos e através do método de balanço de água no solo. Com isso, é possível gerar um calendário de irrigações, com as respectivas datas e lâminas de água a serem aplicadas durante o ciclo da cultura. Desenvolveu-se um trabalho, com a cooperação da UFMG, com o objetivo de aumentar a precisão desse método, utilizando-se Redes Neurais Artificiais (RNAs) para ajustar e predizer a ETo diária, com base em uma série histórica de dados climáticos. Um experimento foi conduzido em duas épocas de plantio (27 de janeiro de 2003 e 02 de setembro de 2003), para testar a precisão desse método em relação ao uso da média de ETo, da ETo predita por RNAs sem ajuste, da ETo calculada diariamente e da evaporação da água do tanque Classe A (ECA), através do balanço de água no solo e do uso de tensiômetros. O manejo das irrigações pelo balanço de água no solo, utilizando-se a ETo estimada diariamente pelo método de Penman-Monteith, considerado como padrão, utilizando-se dados de ETo ajustados e preditos por RNAs e utilizando-se a ECA, proporcionou as maiores produtividades de milho em ambos os experimentos. O manejo utilizando-se valores médios de ETo e valores de ETo preditos e não ajustados de uma série histórica de dados climáticos causou redução de produtividades de milho, em relação ao padrão

    Giant congenital melanocytic nevi and neurocutaneous melanosis

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    Introduction. The major medical concern with giant congenital melanocytic nevi CMN is high risk of developing cutaneous melanoma, leptomeningeal melanoma, and neurocutaneous melanocytosis. Case Report. A 30-year-old woman with a giant congenital melanocytic nevus covering nearly the entire right thoracodorsal region and multiple disseminated melanocytic nevi presented with neurological symptoms. Cerebral magnetic resonance imaging revealed a large expansive lesion in the left frontal region. Postsurgically pathological diagnosis revealed characteristics of melanoma. Immunohistochemical examination showed S100(+), HMB45(+), MelanA(+), and MiTF(+). She received radiotherapy with temozolomide followed by two more chemotherapy cycles with temozolomide. She followed a rapidly progressive course, reflecting widespread leptomeningeal infiltration, and she died of multiorgan failure seven months after diagnosis of cerebral melanoma. Discussion. This patient was diagnosed as having a neurocutaneous melanosis with malignant widespread leptomeningeal infiltration. Diffuse spinal involvement is unusual and is described in only another patient

    Late onset Ito's nevus

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    Dermal melanocytoses include a variety of congenital and acquired melanocytic lesions characterised by the presence of multiple spindle-shaped dendritic melanocytes in the dermis. These lesions are commonly found in the skin of Asians, but they can also appear in Caucasians. The Mongolian spot, nevi of Ota and Ito are the most common morphological forms. We report a case of a 24-year-old Caucasian woman presented with a 10-months history of progressive darkening of the right side of her upper back. Cutaneous examination revealed a macular blue-grey hyperpigmentation of the right side of her upper back. Biopsy specimen from the macule showed multiple darkly pigmented, spindle-shaped dendritic melanocytes in the superficial dermis, interstitially arranged between collagen bundles. The diagnosis of nevus of Ito was established. Our patient is maintaining vigilance in dermatology consultation

    Rapidly lethal dermatomyositis associated with cutaneous lymphangitis carcinomatosa

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    A 70-year-old woman with a recent diagnosis of dermatomyositis (DM) presented to the dermatology department for study of a probably paraneoplastic syndrome. On examination, we observed discrete, indurated, reddish, painful plaques and nodules on her abdomen and both thighs. A cutaneous biopsy from an abdominal nodule, performed as part of the paraneoplastic workup, was suggestive of cutaneous lymphangitis carcinomatosa, secondary to unknown malignancy. An extensive investigation to locate the site of the primary tumour revealed no specific findings. A course of palliative chemotherapy with cisplatin and 5-fluorouracil was then given, but the patient's condition deteriorated and 6 months after her initial observation the patient died. We describe this case because, to our knowledge, the association between DM and cutaneous lymphangitis carcinomatosa has not been described yet in the literature and to highlight that, DM can be a rapidly lethal disease

    Bleomycin-induced flagellate hyperpigmentation

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    Bleomycin is a chemotherapeutic agent used in the treatment of different tumours. It has several side effects, including flagellate hyperpigmentation, which is a unique and a well-documented side effect of bleomycin therapy. We report a case of a 23-year-old woman with a personal history of ovarian dysgerminoma, who developed flagellate hyperpigmentation on trunk after bleomycin therapy
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