39,994 research outputs found
Variability of the 13C-acetate breath test for gastric emptying of liquids in healthy children.
No full textEvidence for the decay B0→J/ψω and measurement of the relative branching fractions of meson decays to J/ψη and J/ψη′
No full textFirst evidence of the B 0 → J / ψ ω decay is found and the B s 0 → J / ψ η and B s 0 → J / ψ η ′ decays are studied using a dataset corresponding to an integrated luminosity of 1.0 fb -1 collected by the LHCb experiment in proton-proton collisions at a centre-of-mass energy of sqrt(s) = 7 TeV. The branching fractions of these decays are measured relative to that of the B 0 → J / ψ ρ 0 decay:frac(B (B 0 → J / ψ ω), B (B 0 → J / ψ ρ 0)) = 0.89 ± 0.19 (stat) - 0.13 + 0.07 (syst),frac(B (B s 0 → J / ψ η), B (B 0 → J / ψ ρ 0)) = 14.0 ± 1.2 (stat) - 1.5 + 1.1 (syst) - 1.0 + 1.1 (frac(f d, f s)),frac(B (B s 0 → J / ψ η ′), B (B 0 → J / ψ ρ 0)) = 12.7 ± 1.1 (stat) - 1.3 + 0.5 (syst) - 0.9 + 1.0 (frac(f d, f s)), where the last uncertainty is due to the knowledge of f d / f s, the ratio of b-quark hadronization factors that accounts for the different production rate of B 0 and B s 0 mesons. The ratio of the branching fractions of B s 0 → J / ψ η ′ and B s 0 → J / ψ η decays is measured to befrac(B (B s 0 → J / ψ η ′), B (B s 0 → J / ψ η)) = 0.90 ± 0.09 (stat) - 0.02 + 0.06 (syst)
New Pliocene and Pleistocene acritarchs from the North Atlantic, Arctic Ocean and Bering Sea
No full textAcritarchs have received limited attention in palynological studies of the Cenozoic, although they have much potential both for refining Neogene and Quaternary stratigraphy, especially in mid- and high northern latitudes, and developing palaeoceanographical reconstructions. Here we formally describe and document the stratigraphical and palaeotemperature ranges (from foraminiferal Mg/Ca) of four new acritarch species: Cymatiosphaera? aegirii sp. nov., Cymatiosphaera? fensomei sp. nov., Cymatiosphaera? icenorum sp. nov. and Lavradosphaera canalis sp. nov. In reviewing the stratigraphical distributions of all species of the genus Lavradosphaera De Schepper & Head, 2008, we demonstrate their correlation potential between the North Atlantic and Bering Sea in the Pliocene. Additionally, Lavradosphaera lucifer De Schepper & Head, 2008 and Lavradosphaera canalis sp. nov., while not themselves overlapping stratigraphically, have morphological intermediates that do partially overlap and may represent an evolutionary trend consequent upon climate cooling in the Late Pliocene. Finally, we show that the highest abundances of the acritarchs presented here were living in the eastern North Atlantic, in surface-water temperatures not very different from today
Measurement of the time-dependent CP asymmetry in B0 -> J/ψ KS0 decays
No full textThis Letter reports a measurement of the CP violation observables SJ/ψK0S and CJ/ψK0S in the decay channel B0→J/ψK0S performed with 1.0 fb−1 of pp collisions at s√=7 TeV collected by the LHCb experiment. The fit to the data yields SJ/ψK0S=0.73±0.07(stat)±0.04(syst) and CJ/ψK0S=0.03±0.09(stat)±0.01(syst). Both values are consistent with the current world averages and within
expectations from the Standard Model
Measurement of the ratio of prompt χ c to J / ψ production in pp collisions at √s = 7 TeV
No full textThe prompt production of charmonium χ c and J / ψ states is studied in proton-proton collisions at a centre-of-mass energy of √s = 7 TeV at the Large Hadron Collider. The χ c and J / ψ mesons are identified through their decays χ c → J / ψ γ and J / ψ → μ + μ - using 36 pb - 1 of data collected by the LHCb detector in 2010. The ratio of the prompt production cross-sections for χ c and J / ψ, σ (χ c → J / ψ γ) / σ (J / ψ), is determined as a function of the J / ψ transverse momentum in the range 2 < p T J / ψ < 15 GeV / c. The results are in excellent agreement with next-to-leading order non-relativistic expectations and show a significant discrepancy compared with the colour singlet model prediction at leading order, especially in the low p T J / ψ region
La investigación antropológica de Roberto J. Weitlaner en Guerrero. 1 Año 1 (2014) enero-marzo. Rutas de Campo. Estudiosos de Guerrero: Semblanzas
No full textDahlgren de J., Barbro, “La obra etnológica del maestro Weitlaner”, en Summa anthropologica en homenaje a Roberto J. Weitlaner, México, INAH, 1966, pp. 25-29.Fernández de M., María Teresa, “La madurez mexicana de Weitlaner”, en Summa anthropologica en homenaje a Roberto J. Weitlaner, México, INAH, 1966, pp. 19-23.Fondo Weitlaner, carpeta XIV.Foster, George M., “Robert J. Weitlaner”, American Anthropologist. vol. 72, pp. 343-346, en línea [http://onlinelibrary. wiley.com/doi/10.1525/aa.1970.72.2.02a00080/full], consultado el 28 octubre de 2009.Jiménez Moreno, Wigberto. “Weitlaner en su mocedad”, en Summa anthropologica en homenaje a Roberto J. Weitlaner, México, INAH, 1966, pp. 9-17.Parcero, María de la Luz, María del Carmen Anzures y Sara Molinari, Nuevo catálogo del Fondo Weitlaner, México, INAH, 1995.Pompa y Pompa, Antonio, “Diálogo con Roberto J. Weitlaner. Entrevista de Antonio Pompa y Pompa”, en Summa anthropologica en homenaje a Roberto J. Weitlaner, México, INAH, 1966, pp. 31-36
Response to “Comment on ‘The viscoelastic response of Brownian suspensions’?” [J. Chem. Phys. 114, 3339 (2001)]
No full textOur original article presented computer simulation results for the viscoelastic response of a simple model colloidal suspension. We compared our results for the viscosity with a theoretical prediction of Verberg et al. [R. Verberg, I. M. de Schepper, and E. G. D. Cohen, Phys. Rev. E 55, 3143 (1997)] and found poor agreement. It is suggested in the previous comment that a comparison with a modified expression is more appropriate. In response we explain the basis of our comparison and expand on how a different interpretation could be made, leading to an expression of the form Felderhof suggests is appropriate. Nonetheless, as stated in the comment, the agreement with simulation is poor, no matter which of the two possible theoretical expressions is used. We also seek to clarify our position concerning the form of the high frequency response at low volume fraction. Our finding is that the ratio of this to the high frequency response in the zero density limit is not the radial distribution function at contact, as predicted by Verberg et al. [R. Verberg, I. M. de Schepper, M. J. Feigenbaum, and E. G. D. Cohen, J. Stat. Phys. 87, 1037 (1997)], but is a rather smaller quantity.Computational PhysicsApplied Science
Stochastic approximations of present value functions.
No full textThe aim of the paper is to apply the method proposed by Denuit, Genest and Marceau (1999) for deriving stochastic upper and lower bounds on the present value of a sequence of cash flows, where the discounting is performed under a given stochastic return process. The convex approximation provided by Goovaerts, Dhaene and De Schepper (1999) and Goovaerts and Dhaene (1999) is then compared to these stochastic bounds. On the basis of several numerical examples, it will be seen that the convex approximation seems reasonable.Value; Functions;
Spin-echo development for a time-of-flight neutron reflectometer
No full textNeutron scattering techniques are a useful tool to determine structures in samples with sizes ranging from 1 x 10-10 up to 1 x 10-5 meter. Unfortunately powerful neutron sources are scares and expensive, which demands an efficient use of the available neutrons. This thesis focuses mainly on the practical realisation of a combination of two neutron scattering techniques; neutron reflectometry and neutron spin-echo angle labelling. This special combination will not only result in more efficient neutron scattering measurements but will also open up possibilities for new types of measurements. OffSpec is a new dedicated spin-echo reflectometer which is designed to accommodate the fusion of the two techniques and is located at the Second Target Station at ISIS in the United Kingdom. It will be ready for user operation mid 2009. Delft University of Technology has been responsible for the development and production of the spin-echo components for OffSpec. A flexible mechanical design results in five different applications for this spectrometer: ultra small-angle scattering by spin-echo, high intensity measurements on in-plane - nanometre to micrometre - correlations, high resolution measurements for bent or wavy samples, possibility to separate specular and off-specular scattering within a detector pixel, and inelastic spin-echo in transmission or in reflection. A large part of this thesis work consists of the design and build of these spin-echo components. A dedicated beam at the Reactor Institute Delft was used to test the components and built a number of prototypes spectrometers. These prototypes were used to perform proof of principle measurements for several different instrumental modes which are described in this thesis.Radiation, radionuclides & reactorsApplied Science
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