150 resultados para Flash Events


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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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The inclusive production cross sections for forward jets, as well for jets in dijet events with at least one jet emitted at central and the other at forward pseudorapidities, are measured in the range of transverse momenta p(T) = 35-150 GeV/c in proton-proton collisions at root s = 7 TeV by the CMS experiment at the LHC. Forward jets are measured within pseudorapidities 3.2<|eta|<4.7, and central jets within the |eta|<2.8 range. The double differential cross sections with respect to pt and eta are compared to predictions from three approaches in perturbative quantum chromodynamics: (i) next-to-leading-order calculations obtained with and without matching to parton-shower Monte Carlo simulations, (ii) PYTHIA and HERWIG parton-shower event generators with different tunes of parameters, and (iii) CASCADE and HEJ models, including different non-collinear corrections to standard single-parton radiation. The single-jet inclusive forward jet spectrum is well described by all models, but not all predictions are consistent with the spectra observed for the forward-central dijet events.

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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Compararam-se os eventos clínicos e as variações da pressão intra-ocular (PIO) das técnicas facoemulsificação endocapsular e extração extracapsular com modificações, no intra e no pós-operatório imediato. A facoemulsificação resultou em menor edema corneano, menor desconforto ocular e menos intercorrências no pós-operatório em relação à extração extracapsular modificada. É imperativo que se faça o monitoramento da PIO no pós-operatório, uma vez que ela ocorreu na facoemulsificação, e o uso de hipotensores oculares, quando os valores da PIO ultrapassarem os limites aceitáveis.

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In this study the Minos element was analyzed in 26 species of the repleta group and seven species of the saltans group of the genus Drosophila. The PCR and Southern blot analysis showed a wide occurrence of the Minos transposable element among species of the repleta and the saltans groups and also a low number of insertions in both genomes. Three different analyses, nucleotide divergence, historical associations, and comparisons between substitution rates (d(N) and d(S)) of Minos and Adh host gene sequences, suggest the occurrence of horizontal transfer between repleta and saltans species. These data reinforce and extend the Arca and Savakis [Genetica 108 (2000) 263] results and suggest five events of horizontal transfer to explain the present Minos distribution: between D. saltans and the ancestor of the mulleri and the mojavensis clusters; between D. hydei and the ancestor of the mulleri and the mojavensis clusters; between D. mojavensis and D. aldrichi; between D. buzzatii and D. serido; and between D. spenceri and D. emarginata. An alternative explanation would be that repeated events of horizontal transfer involving D. hydei, which is a cosmopolitan species that diverged from the others repleta species as long as 14 Mya, could have spread Minos within the repleta group and to D. saltans. The data presented in this article support a model in which distribution of Minos transposon among Drosophila species is determined by horizontal transmission balanced by vertical inactivation and extinction. (c) 2004 Elsevier B.V. All rights reserved.

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Both narrow and broad photoluminescence bands were observed in Ga1-XAsX films prepared by flash evaporation of polycrystalline GaAs containing native C impurities. The observed narrow crystalline-like bands are similar to band-to-band and C acceptor impurity emissions in crystalline GaAs. The narrow bands are evidence that the As excess favors the PL active GaAs crystallite formation in films deposited onto silicon (10 0) substrate, even when the As excess is very large (X = 0.84). This favoring is not observed in twin samples grown on silica glass substrates nor on Ga rich samples, indicating the important role of the combined effect of the As excess and Si substrate in the GaAs crystallite formation. The broad amorphous-like bands were observed in Ga rich and in moderately As rich samples. The photoluminescence emission is compared with the microstructure of the material as determined from the micro-Raman, absorption edge and reflectance measurements. The volume fraction of the crystallites formed is small and PL emission indicates that the crystallite electronic quality is much better than the ones formed heat treating films grown on silica glass substrates. (C) 2004 Elsevier B.V. All rights reserved.

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This study investigated the effect of non-ventilation of the incubator during the first 10 days of incubation and its combination with dexamethasone administration at day 16 or 18 of incubation on hatching parameters and embryo and post-hatch chick juvenile physiology. A total of 2400 hatching eggs produced by Cobb broiler breeders were used for the study. Blood samples were collected at day 18 of incubation, at internal pipping stage (IP), at the end of hatch (day-old chick) and at 7-daypost-hatch for T-3, T-4 and corticosterone levels determination. From 448 to 506 h of incubation, the eggs were checked individually in the hatcher every 2 h for pipping and hatching. The results indicate that non-ventilation during the first 10-day shortened incubation duration up to IP, external pipping (EP) and hatch, had no effect on hatchability and led to higher T-3 levels at IP but lower corticosterone levels at 7-day-post-hatch. The injection of dexamethasone at days 16 and 18 of incubation affected hatching and blood parameters in both the ventilated and non-ventilated embryos differentially and the effect was dependent on the age of the embryo. Dexamethasone increased T-3 levels and T-3/T-4 ratios but the effect was greater with early non-ventilation of eggs. Dexamethasone decreased hatchability but the effect was greater when injected at day 16 and especially in ventilated embryos. The effects of incubation protocols and dexamethasone treatments during incubation were still apparent in the hatched chicks until 7 days of age. The changes in T-3, T-4 and corticosterone levels observed in response to the early incubation conditions and late dexamethasone treatments in this study suggest that incubator ventilation or non-ventilation may influence the hypothalamic-pituitary-adrenal axis (HPA) regulation of stress levels (in terms of plasma corticosterone levels) and thyroid function in the embryo with impact on incubation duration, hatching events and early post-hatch life of the chick. Our results also suggest that some stages of development are more sensitive to dexamethasone administration as effects can be influenced by early incubation protocols. (c) 2006 Elsevier B.V. All rights reserved.

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A contact four-fermion interaction between light quarks and electrons has been evoked as a possible explanation for the excess of events observed by HERA at high-Q2. We explore the 1-loop effects of such interaction in Γ(Z0 → e+e-) measured at LEP and impose strong bounds on the lower limit of the effective scale. Our results are able to discard some of the contact interactions as possible explanation for the HERA events. © 1997 Elsevier Science B.V.