3,352 research outputs found
The Beta Generalized Exponential Distribution
We introduce the beta generalized exponential distribution that includes the
beta exponential and generalized exponential distributions as special cases. We
provide a comprehensive mathematical treatment of this distribution. We derive
the moment generating function and the th moment thus generalizing some
results in the literature. Expressions for the density, moment generating
function and th moment of the order statistics also are obtained. We discuss
estimation of the parameters by maximum likelihood and provide the information
matrix. We observe in one application to real data set that this model is quite
flexible and can be used quite effectively in analyzing positive data in place
of the beta exponential and generalized exponential distributions
Potencial produtivo de própolis em diferentes espécies de abelhas sem ferrão.
A própolis é um material de origem vegetal bastante estudado para fins farmacológicos. Dentre os principais constituintes desse material estão: resinas, ceras e ácidos gordurosos, inerentes à vegetação que circunda a colônia de meliponíneos. Para estes, ainda não existem estudos suficientes que comprovem o poder farmacológico da própolis, não sendo ainda recomendado seu uso para fins terapêuticos, por isso são necessárias mais pesquisas para esse fim. Para a realização do trabalho foram utilizadas 6 espécies de abelhas sem ferrão, das quais 3 espécies produzem própolis com resinas puras e as outras 3 fazem a produção do batume ou geoprópolis (Resina + Barro). As espécies utilizadas foram: Frieseomelitta cf. longipes, F. flavicornis, Scaptotrigona postica, Melipona flavolineata, M. fasciculata e M. melanoventer. Utilizou-se 18 coletores de própolis, sendo 9 coletores com dimensões de 20x20cm e 9 coletores de 30x30cm, ambos com altura de 2,5cm que eram trocados de 15 em 15 dias, tempo hábil para o preenchimento total da fresta. O experimento foi realizado no laboratório de botânica da Embrapa Amazônia Oriental, no período de outubro de 2013 a maio de 2014. Entre as espécies produtoras de batume, a M. flavolineata foi a que melhor se destacou ficando com uma produção média de 188,50 g (±121,76). Entre as espécies produtoras de própolis com resina pura, a que melhor se destacou foi a Frieseomelitta cf. longipes com uma média de 36,65g (±15,87)
Glaucoma: the retina and beyond
Over 60 million people worldwide are diagnosed with glaucomatous optic neuropathy, which is estimated to be responsible for 8.4 million cases of irreversible blindness globally. Glaucoma is associated with characteristic damage to the optic nerve and patterns of visual field loss which principally involves the loss of retinal ganglion cells (RGCs). At present, intraocular pressure (IOP) presents the only modifiable risk factor for glaucoma, although RGC and vision loss can continue in patients despite well-controlled IOP. This, coupled with the present inability to diagnose glaucoma until relatively late in the disease process, has led to intense investigations towards the development of novel techniques for the early diagnosis of disease. This review outlines our current understanding of the potential mechanisms underlying RGC and axonal loss in glaucoma. Similarities between glaucoma and other neurodegenerative diseases of the central nervous system are drawn before an overview of recent developments in techniques for monitoring RGC health is provided, including recent progress towards the development of RGC specific contrast agents. The review concludes by discussing techniques to assess glaucomatous changes in the brain using MRI and the clinical relevance of glaucomatous-associated changes in the visual centres of the brain
Unilateral progressive osseous heteroplasia
A 50-year-old male patient presented with firm subcutaneous nodules and plaques with a gritty texture, unilaterally affecting the left side of the trunk and the left limbs. These lesions had had a progressive course since early childhood and caused functional impairment. There was no family history of similar disorders. No phospho-calcium metabolism abnormalities were observed. Biopsies of the affected areas demonstrated osteoma cutis. Analysis of DNA showed no mutation of the GNAS gene. The clinical features were consistent with progressive osseous heteroplasia, atypically presented in a unilateral form, probably revealing a mosaic distribution
Alterações clínicas e cardiopulmonares produzidas pelo envenenamento escorpiônico em cães
O artigo não apresenta resumo
Tapered GRIN fiber microsensor
FAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULOThe sensitivity of an optical fiber microsensor based on inter-modal interference can be considerably improved by tapering a short extension of the multimode fiber. In the case of Graded Index fibers with a parabolic refractive index profile, a meridional ray exhibits a sinusoidal path. When these fibers are tapered, the period of the propagated beam decrease down-taper and increase up-taper. We take advantage of this modulation -along with the enhanced overlap between the evanescent field and the external medium- to substantially increase the sensitivity of these devices by tuning the sensor's maximum sensitivity wavelength. Moreover, the extension of this device is reduced by one order of magnitude, making it more propitious for reduced space applications. Numerical and experimental results demonstrate the success and feasibility of this approach.The sensitivity of an optical fiber microsensor based on inter-modal interference can be considerably improved by tapering a short extension of the multimode fiber. In the case of Graded Index fibers with a parabolic refractive index profile, a meridional ray exhibits a sinusoidal path. When these fibers are tapered, the period of the propagated beam decrease down-taper and increase up-taper. We take advantage of this modulation -along with the enhanced overlap between the evanescent field and the external medium- to substantially increase the sensitivity of these devices by tuning the sensor's maximum sensitivity wavelength. Moreover, the extension of this device is reduced by one order of magnitude, making it more propitious for reduced space applications. Numerical and experimental results demonstrate the success and feasibility of this approach.22253043230441FAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULOFAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO2011/01524-8Tam, H.Y., Liu, S.Y., Guan, B.O., Chung, W.H., Chan, T.H., Cheng, L.K., Fiber bragg grating sensors for structural and railway applications (2005) Advanced Sensor Systems and Applications II, 5634, pp. 85-97Villatoro, J., Monzón-Hernández, D., Mejía, E., Fabrication and modeling of uniform-waist single-mode tapered optical fiber sensors (2003) Appl. Opt., 42, pp. 2278-2283Kumar, A., Varshney, R.K., Sa, C., Sharma, P., Transmission characteristics of SMS fiber optic sensor structures (2003) Optics Communications, 219, pp. 215-219Tripathi, S.M., Kumar, A., Varshney, R.K., Kumar, Y.P., Marin, E., Meunier, J.-P., Strain and temperature sensing characteristics of single-mode-multimode-single-mode structures (2009) J. Lightwave Technol., 27, pp. 2348-2356Biazoli, C.R., Silva, S., Franco, M.A.R., Frazão, O., Cordeiro, C.M.B., Multimode interference tapered fiber refractive index sensors (2012) Appl. Opt., 51, pp. 5941-5945Beltrán-Mejía, F., Osório, J.H., Biazoli, C.R., Cordeiro, C.M.B., D-microfibers (2013) J. Lightwave Technol., 31, pp. 2756-2761Wang, P., Brambilla, G., Ding, M., Semenova, Y., Wu, Q., Farrell, G., Investigation of single-mode-multimode-single-mode and single-mode-tapered-multimode-single-mode fiber structures and their application for refractive index sensing (2011) J. Opt. Soc. Am. B, 28, pp. 1180-1186Pillai, R.S., Lorenser, D., Sampson, D.D., Deep-tissue access with confocal fluorescence microendoscopy through hypodermic needles (2011) Opt. Express, 19, pp. 7213-7221Liu, Y., Wei, L., Low-cost high-sensitivity strain and temperature sensing using graded-index multimode fibers (2007) Appl. Opt., 46, pp. 2516-2519(2014) Comsol Multiphysics, , Burlington, MA, USA Version 4.4Ghatak, A., Thyagarajan, K., (1998) An Introduction to Fiber Optics, , Cambridge University Press, chap 9Shiraishi, K., Kuroo, S.-I., A new lensed-fiber configuration employing cascaded GI-fiber chips (2000) J. Lightwave Technol., 18, p. 787Guenther, R.D., (1990) Modern Optics, , Wiley, chap.9Kogelnik, H., On the propagation of gaussian beams of light through lenslike media including those with a loss or gain variation (1965) Appl. Opt, 4, pp. 1562-1569Birks, T., Li, Y., The shape of fiber tapers (1992) J. Lightwave Technol., 10, pp. 432-43
[Carotid atherosclerosis and white matter hypodensities: a controversial relationship]
INTRODUCTION:
White matter hypodensities of presumed vascular origin, are recognized as an important cause of morbidity with established clinical and cognitive consequences. Nonetheless, many doubts remain on its physiopathology. Our goal is to clarify the potential role of carotid atherosclerosis and other vascular risk factors in the development of white matter hypodensities of presumed vascular origin.
MATERIAL AND METHODS:
We included patients that underwent CT brain scan and neurosonologic evaluation within a one-month period. Full assessment of vascular risks factors was performed. We seek to find independent associations between white matter hypodensities of presumed vascular origin, carotid intima-media thickness and vascular risk factors.
RESULTS:
472 patients were included, mean age was 67.32 (SD: 14.75), 274 (58.1%) were male. The independent predictors of white matter hypodensities of presumed vascular origin were age (OR: 1.067, 95% IC: 1.049 - 1.086, p < 0.001) and hypertension (OR: 1.726, 95% IC: 1.097 - 2.715, p = 0.018). No association was found between IMT (OR: 2.613, 95% IC: 0.886 - 7.708, p = 0.082) or carotid artery stenosis (OR: 1.021, 95% IC: 0.785 - 1.328, p = 0.877) and white matter hypodensities of presumed vascular origin.
DISCUSSION:
Only age and hypertension proved to have an independent association with white matter hypodensities of presumed vascular origin. Carotid atherosclerosis, evaluated by IMT and the degree of carotid artery stenosis, showed no association with white matter hypodensities of presumed vascular origin. Since atherosclerosis is a systemic pathology, these results suggest that alternative mechanisms are responsible for the development of white matter hypodensities of presumed vascular origin.
CONCLUSION:
Age and hypertension seem to be the main factors in the development of white matter hypodensities of presumed vascular origin. No association was found between carotid atherosclerosis and white matter hypodensities of presumed vascular origin
Análise comparativa de rentabilidade: Brs Platina e Prata Anã.
A banana é a segunda fruta ais produzida e consumida no Brasil, com área colhida de 503 mil hectares e produção de 7,3 milhões de toneladas em 2011 (1). A maior parte do cultivo é realizada em pequenas propriedades. A variedade de maior produção e comercialização no Brasil é a ?Prata Anã?. No entanto, a suscetibilidade à Sigatoka-amarela e ao mal-do-Panamá estimulou a busca por variedades resistentes a tais doenças, resultando na variedade ?BRS Platina?
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