946 resultados para time measurement
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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We present a study of the decay B-s(0)-> J/psi phi. We obtain the CP-odd fraction in the final state at time zero R-perpendicular to = 0.16 +/- 0.10 (stat) +/- 0.02(syst), the average lifetime of the (B-s(0), (B) over bar (0)(s)) system, (tau) over bar (B-s(0)) = 1.39(-0.16)(+0.13)(stat)(-0.02)(+0.01)(syst) ps, and the relative width difference between the heavy and light mass eigen-states, Delta Gamma/(Gamma) over bar = (Gamma(L) - Gamma(H))/(Gamma) over bar = 0.24(-0.38)(+0.28)(stat)(-0.04)(+0.03)(syst). With the additional constraint from the world average of the B-s(0) lifetime measurements using semileptonic decays, we find (tau) over bar (B-s(0)) = 1.39 +/- 0.06 ps and Delta Gamma/(Gamma) over bar = 0.25(-0.15)(+0.14). For the ratio of the B-s(0) and B-0 lifetimes we obtain (tau) over bar (B-s(0))/tau(B-s(0)) = 0.91 +/- 0.09(stat) +/- 0.003(syst).
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We have performed the first direct measurement of the time-integrated flavor untagged charge asymmetry in semileptonic B-s(0) decays A(SL)(s,unt) by comparing the decay rate of B-s(0) -> mu(+) D-s(-) nu X, where D-s(-) -> phi pi(-) and phi -> K+K-, with the charge-conjugate (B) over bar (0)(s) decay rate. This sample was selected from 1: 3 fb(-1) of data collected by the D0 experiment in run II of the Fermilab Tevatron collider. We obtain A(SL)(s,unt) = [1.23 +/- 0.97(stat) +/- 0.17(syst)] x 10(-2). Assuming that Delta m(s)/(Gamma) over bar (s) >> 1, this result can be translated into a measurement of the CP-violating phase in B-s(0) mixing: Delta Gamma(s)/Delta m(s) tan phi(s) = [2.45 +/- 1.93(stat) +/- 0.35(syst)] x 10(-2).
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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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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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A significant part of film production by the coating industry is based on wet bench processes, where better understanding of their temporal dynamics could facilitate control and optimization. In this work, in situ laser interferometry is applied to study properties of flowing liquids and quantitatively monitor the dip coating batch process. Two oil standards Newtonian, non-volatile, with constant refractive indices and distinct flow properties - were measured under several withdrawing speeds. The dynamics of film physical thickness then depends on time as t(-1/2), and flow characterization becomes possible with high precision (linear slope uncertainty of +/-0.04%). Resulting kinematic viscosities for OP60 and OP400 are 1,17 +/- 0,03. St and 9,9 +/- 0,2 St, respectively. These results agree with nominal values, as provided by the manufacturer. For more complex films (a multi-component sol-gel Zirconyl Chloride aqueous solution) with a varying refractive index, through a direct polarimetric measurement, allowing also determination of the temporal evolution of physical thickness (uncertainty of +/- 0,007 microns) is also determined during dip coating.
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Objective: To assess the reliability of the standing measurement of hand-to-foot bioimpedance compared with measurements made in the lying position.Research Methods and Procedures: In 205 volunteers 6 to 89 years of age, 111 males and 94 females from six ethnic groups, effects of posture, time, and age on hand-to-foot resistance were studied over a range of body size. The effect of time in a position on resistance was also recorded in a small subset (n = 10), and repeat measurements over 3 days at the same time of the day were recorded in another subset (n = 12).Results: Lying impedance was consistently higher than standing, with the relationship (resistance lying/resistance standing) for the children (5 to 14 years) being 1.031, progressing to a ratio of 1.016 in those >60 years. The time spent static in either position did change resistance measurements - a decrease of up to 9 Omega (mean 5 Omega, 1.0%) over 10 minutes of standing and an increase of up to 7 Omega (mean 3 Omega, 0.7%) with lying.Discussion: In the field, measurements of hand-to-foot bioimpedance can be made in the standing position, and, with appropriate adjustment, previously validated recumbent equations can be used. Given that errors in the measurement of height and weight also affect the reliability of the derivation of body fat from bioelectrical conductance, the errors that may arise from a more practical standing measurement rather than lying are minimal.
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This paper reports on time-resolved emission and excitation spectra measurement studies of Gd2SiO5:Ce3+ in powder or pellet samples, from spherical particles, in order to assign the Ce3+ ion transitions into two different symmetry sites. Samples were obtained from solid-state reaction of the spherical particles oxides, SiO2 and Gd2O3:Ce3+. From time-resolved spectroscopy measurements Ce3+ ion transitions occupying the two different gadolinium crystallographic sites in Gd2SiO5 were separated and assigned. (C) 2002 Elsevier B.V. B.V. All rights reserved.
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In this paper we present and demonstrate a technique that allows simultaneous and independent measurement of small changes in the refractive index and the absorption coefficient produced in photosensitive materials during holographic exposure. The technique is based on the synchronous detection of two-wave mixing signals in both directions of the transmitted interfering beams. By processing both signals it is possible to separate the diffraction contributions of the refractive index from the absorption coefficient and simultaneously stabilize the incident fringe pattern. The demonstration of this technique is undertaken by following the temporal evolution of the phase and amplitude modulations in photoresist films. To check the ability of the technique to perform numeric evaluations, for a positive photoresist the changes in the optical constants were measured and compared with those obtained using independent methods.
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The magnetorefractive effect (MRE) has been used for the first time to study the magnetotransport properties of La1-xSrxMnO3 perovskite materials. A direct correlation between the MRE and colossal magnetoresistance was observed. Samples with x = 0-0.3 prepared using the homogeneous coprecipitation and the solid state reaction methods were studied, covering the range of insulating to metallic behaviour. The M RE probed both the magnetically induced modification of the scattering of Drude-like electrons and the magnetic dependence of a stretching vibration mode. (C) 2004 Elsevier B.V. All rights reserved.
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)