2,872 research outputs found

    Severe Thyroid-associated Ophtalmopathy and Hashimoto´s Thyroiditis in Euthyroid Patient

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    Pricing and Hedging Asian Basket Options with Quasi-Monte Carlo Simulations

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    In this article we consider the problem of pricing and hedging high-dimensional Asian basket options by Quasi-Monte Carlo simulation. We assume a Black-Scholes market with time-dependent volatilities and show how to compute the deltas by the aid of the Malliavin Calculus, extending the procedure employed by Montero and Kohatsu-Higa (2003). Efficient path-generation algorithms, such as Linear Transformation and Principal Component Analysis, exhibit a high computational cost in a market with time-dependent volatilities. We present a new and fast Cholesky algorithm for block matrices that makes the Linear Transformation even more convenient. Moreover, we propose a new-path generation technique based on a Kronecker Product Approximation. This construction returns the same accuracy of the Linear Transformation used for the computation of the deltas and the prices in the case of correlated asset returns while requiring a lower computational time. All these techniques can be easily employed for stochastic volatility models based on the mixture of multi-dimensional dynamics introduced by Brigo et al. (2004).Comment: 16 page

    Light-cone averages in a swiss-cheese universe

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    We analyze a toy swiss-cheese cosmological model to study the averaging problem. In our model, the cheese is the EdS model and the holes are constructed from a LTB solution. We study the propagation of photons in the swiss-cheese model, and find a phenomenological homogeneous model to describe observables. Following a fitting procedure based on light-cone averages, we find that the the expansion scalar is unaffected by the inhomogeneities. This is because of spherical symmetry. However, the light-cone average of the density as a function of redshift is affected by inhomogeneities. The effect arises because, as the universe evolves, a photon spends more and more time in the (large) voids than in the (thin) high-density structures. The phenomenological homogeneous model describing the light-cone average of the density is similar to the concordance model. Although the sole source in the swiss-cheese model is matter, the phenomenological homogeneous model behaves as if it has a dark-energy component. Finally, we study how the equation of state of the phenomenological model depends on the size of the inhomogeneities, and find that the equation-of-state parameters w_0 and w_a follow a power-law dependence with a scaling exponent equal to unity. That is, the equation of state depends linearly on the distance the photon travels through voids. We conclude that within our toy model, the holes must have a present size of about 250 Mpc to be able to mimic the concordance model.Comment: 20 pages, 14 figures; replaced to fit the version accepted for publication in Phys. Rev.

    Banco de estacas para multiplicação de Gliricidia sepium: uma espécie de múltiplo uso.

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    Avaliação do desempenho de banco de estacas de gliricidia implantado em áreas degradadas e determinação da relação entre diâmetro e comprimento das estacas com a qualidade das hastes que elas produzem visando acelerar a produção de material multiplicativo dessa espécie

    Comparison of indoor and outdoor fungi and particles in poultry units

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    A descriptive study was developed in order to compare indoor and outdoor air contamination caused by fungi and particles in seven poultry units. Twenty eight air samples of 25 litters were collected through the impaction method on malt extract agar. Air sampling and particles concentration measurement were done in the interior and also outside premises of the poultries’ pavilions. Regarding the fungal load in the air, indoor concentration of mold was higher than outside air in six poultry units. Twenty eight species / genera of fungi were identified indoor, being Scopulariopsis brevicaulis (40.5%) the most commonly isolated species and Rhizopus sp. (30.0%) the most commonly isolated genus. Concerning outdoor, eighteen species/genera of fungi were isolated, being Scopulariopsis brevicaulis (62.6%) also the most isolated. All the poultry farms analyzed presented indoor fungi different from the ones identified outdoors. Regarding particles’ contamination, PM2.5, PM5.0 and PM10 had a statistically significant difference (Mann-Whitney U test) between the inside and outside of the pavilions, with the inside more contaminated (p=.006; p=.005; p=.005, respectively). The analyzed poultry units are potential reservoirs of substantial amounts of fungi and particles and could therefore free them in the atmospheric air. The developed study showed that indoor air was more contaminated than outdoors, and this can result in emission of potentially pathogenic fungi and particles via aerosols from poultry units to the environment, which may post a considerable risk to public health and contribute to environmental pollution

    Study of the photodegradation of tribenuron-methyl in aqueous solution of two Moroccan soils

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    Photodegradation of Tribenuron-methyl [methyl 2-(((((4-methoxy-6-methyl-1,3,5-triazin-2- yl)methylamino)carbonyl)amino)sulfonyl)benzoate] was carried out in aqueous solution under UV light. The research of the structures of the photoproducts highlighted by follow-up CLHP was carried out by coupling CLHP/SM. The results of this study allowed concluding that the transformation of the tribenuron-methyl depends on the pH of the medium and the light of irradiation. With this intention, the study of the retention, the mineralization of the tribenuron-methyl in two Moroccan soils of the area of Gharb (Northwest of Morocco) called Tirs and Dehs was carried out using the molecule labelled on carbon ureic and in controlled conditions. The adsorption and desorption of the tribenuron-methyl by the two grounds were carried out by the method of Batch balancing. The adsorption of the active matter follows a nonlinear isotherm. The ground Dehs has a more important affinity for the molecule the tribenuron-methyl than the ground Tirs. The desorption of the tribenuron-methyl is more important starting from the ground Dehs. The mineralization of the molecule by biological way is more important starting from the ground Tirs. The contribution of nitrogen seems to inhibit the process of mineralization starting from this ground

    The Na+/glucose cotransporters: from genes to therapy

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    Glucose enters eukaryotic cells via two types of membrane-associated carrier proteins, the Na+/glucose cotransporters (SGLT) and the facilitative glucose transporters (GLUT). The SGLT family consists of six members. Among them, the SGLT1 and SGLT2 proteins, encoded by the solute carrier genes SLC5A1 and SLC5A2, respectively, are believed to be the most important ones and have been extensively explored in studies focusing on glucose fluxes under both physiological and pathological conditions. This review considers the regulation of the expression of the SGLT promoted by protein kinases and transcription factors, as well as the alterations determined by diets of different compositions and by pathologies such as diabetes. It also considers congenital defects of sugar metabolism caused by aberrant expression of the SGLT1 in glucose-galactose malabsorption and the SGLT2 in familial renal glycosuria. Finally, it covers some pharmacological compounds that are being currently studied focusing on the interest of controlling glycemia by antagonizing SGLT in renal and intestinal tissues

    Real-time evaluation of two light delivery systems for photodynamic disinfection of Candida albicans biofilm in curved root canals

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    Antimicrobial photodynamic therapy (APDT) combined with endodontic treatment has been recognized as an alternative approach to complement conventional root canal disinfection methods on bacterial biofilms. We developed an in vitro model of bioluminescent Candida albicans biofilm inside curved dental root canals and investigated the microbial reduction produced when different light delivery methods are employed. Each light delivery method was evaluated in respect to the light distribution provided inside curved root canals. After conventional endodontic preparation, teeth were sterilized before canals were contaminated by a bioluminescent strain of C. albicans (CEC789). Methylene blue (90 μM) was introduced into the canals and then irradiated (λ = 660 nm, P = 100 mW, beam diameter = 2 mm) with laser tip either in contact with pulp chamber or within the canal using an optical diffuser fiber. Light distribution was evaluated by CCD camera, and microbial reduction was monitored through bioluminescence imaging. Our findings demonstrated that the bioluminescent C. albicans biofilm model had good reproducibility and uniformity. Light distribution in dental tissue was markedly dependent on the light delivery system, and this strategy was directly related to microbial destruction. Both light delivery systems performed significant fungal inactivation. However, when irradiation was performed with optical diffuser fiber, microbial burden reduction was nearly 100 times more effective. Bioluminescence is an interesting real-time analysis to endodontic C. albicans biofilm inactivation. APDT showed to be an effective way to inactivate C. albicans biofilms. Diffuser fibers provided optimized light distribution inside curved root canals and significantly increased APDT efficiency.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP, grant 2010/13313-9)Conselho Nacional de Pesquisas (Brazil) Conselho Nacional de Desenvolvimento Cientifico e TecnologicoNational Institute of Mental Health (U.S.) (NIH R01AI050875

    Interferência do material de construção na temperatura do ar no interior do escamoteador.

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    O desenvolvimento dos leitões na maternidade constitui-se um fator determinante para o sucesso econômico na granja. Dessa forma, objetivou-se avaliar o conforto térmico de dois escamoteadores diferentes para leitões. Foi utilizada uma sala com quatro celas parideiras individual, sendo dois escamoteadores de madeira e dois de polietileno. No interior de cada escamoteador e no centro geométrico de cada sala foi instalado um datalogger de temperatura e umidade. Os dados foram coletados em quatro lotes durante três semanas a cada 30 minutos. Essas variáveis foram analisadas, por meio do modelo de medidas repetidas. O escamoteador de polietileno foi mais adequado com 27,36 % e 27,19 % dos dados dentro da faixa de conforto, enquanto o de madeira obteve 13,61% e 23,85% nas semanas 1 e 2 respectivamente. Somente na terceira semana o escamoteador de madeira obteve melhores resultados com 42,45% enquanto o de polietileno obteve 16,52% dos dados dentro da faixa de conforto. Ambos os escamoteadores obtiveram bons resultados quanto a umidade, obtendo média de dados dentro da faixa ideal de 58,30% o de polietileno e 69,85%, o de madeira. Piglet development in the farrowing house is a determining factor for the economic success the farm. The objective was to evaluate the thermal comfort of two different creeps for piglets. For this, it was used a farrowing house with four individual cells, twomade of wood, and two ofpolyethylene. Inside each creep and at the geometric center of each room , a datalogger was installed for recording the temperature and humidity. Data were collected in four batches every 30 minutes for three weeks. These variables were analyzed using a repeated measures model. The polyethylene creep was the most suitable with 27.36 % and 27.19% of the data within the comfort range, while the wooden creep achieved 13.61 % and 23.85% , in the weeks 1 and 2, respectively. Only on the third week the wood creep presented better results, with 42.45%, whereas that of polyethylene attained 16.52% of the data within the comfort rang. Both creeps achieved satisfactory results for the humidity, reaching mean values within the appropriate range, 58.30% and 69.85%, for polyethylene and wood creeps, respectively

    The Asiago-ESO/RASS QSO Survey. III. Clustering analysis and its theoretical interpretation

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    This is the third paper of a series describing the Asiago-ESO/RASS QSO survey (AERQS), a project aimed at the construction of an all-sky statistically well-defined sample of relatively bright QSOs (B<15) at z<0.3. We present here the clustering analysis of the full spectroscopically identified database (392 AGN). The clustering signal at 0.02<z<0.22 is detected at a 3-4 sigma level and its amplitude is measured to be r_0=8.6\pm 2.0 h^{-1} Mpc (in a LambdaCDM model). The comparison with other classes of objects shows that low-redshift QSOs are clustered in a similar way to Radio Galaxies, EROs and early-type galaxies in general, although with a marginally smaller amplitude. The comparison with recent results from the 2QZ shows that the correlation function of QSOs is constant in redshift or marginally increasing toward low redshift. We discuss this behavior with physically motivated models, deriving interesting constraints on the typical mass of the dark matter halos hosting QSOs, M_DMH= 10^{12.7} h^{-1} M_sun (10^{12.0}-10^{13.5}h^{-1} M_sun at 1 sigma confidence level). Finally, we use the clustering data to infer the physical properties of local AGN, obtaining M_BH=2 10^8 h^{-1} M_sun (10^7-3 10^9 h^{-1} M_sun) for the mass of the active black holes, tau_{AGN}= 8 10^6 yr (2 10^{6}-5 10^{7} yr) for their life-time and eta = 0.14 for their efficiency (always for a LambdaCDM model).Comment: 37 pages, Astronomical Journal in press. Changes to match the referee comment
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