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181.
Wolfgang J. Bühler Prem S. Puri Hans-J. Schuh 《Annals of the Institute of Statistical Mathematics》1990,42(4):603-621
In a recent article Mallows and Nair (1989,Ann. Inst. Statist. Math.,41, 1–8) determined the probability of intersectionP{X(t)=αt for somet≥0} between a compound Poisson process {X(t), t≥0} and a straight line through the origin. Using four different approaches (direct probabilistic, via differential equations
and via Laplace transforms) we extend their results to obtain the probability of intersection between {X(t), t≥0} and arbitrary lines. Also, we display a relationship with the theory of Galton-Watson processes. Additional results concern
the intersections with two (or more) parallel lines.
Work done in part while these authors were visiting professors at the Indian Statistical Institute, Delhi Centre, New Delhi,
110016, India.
This author's investigation was supported in part by the U. S. National Science Foundation Grant No. DMS-8504319.
Our coauthor and friend Prem Singh Puri died on August 12, 1989. We dedicate our contribution to this paper to his memory. 相似文献
182.
The evolution of Δm = 2 ground state coherences was investigated in a thermal Rb atomic beam using spatially separated laser beams. The coherence was created by optical pumping with a linearly polarized light beam and was probed, after evolving in a homogeneous magnetic field via the rotation of the plane of polarization of a second light beam. The observed signal shows dispersively shaped Ramsey fringes with a fringe width of 6 kHz. 相似文献
183.
D. Hippe H. -W. Schuh B. Heits A. Rademacher K. -O. Zell P. v. Brentano J. Eberth E. Eube 《Zeitschrift für Physik A Hadrons and Nuclei》1978,284(3):329-341
Levels in105Ag were populated by the103Rh(α, 2nγ) reaction,γ-singles spectra,γγ-coincidences, excitation functions, angular distributions and polarisation measurements were taken. These measurements were used to construct a level-scheme and give various spin and parity assignments. Nuclear Reactions:103Rh(α, 2nγ)105Ag; measuredEγ, Iγ, γγ-coincidences, excitation functions, angular distributions, polarisation. 相似文献
184.
Jessop CP Marsiske H Perl ML Savinov V Ugolini D Zhou X Coan TE Fadeyev V Maravin Y Narsky I Stroynowski R Ye J Wlodek T Artuso M Ayad R Boulahouache C Bukin K Dambasuren E Karamov S Majumder G Moneti GC Mountain R Schuh S Skwarnicki T Stone S Viehhauser G Wang JC Wolf A Wu J Kopp S Csorna SE Danko I McLean KW Márka S Xu Z Godang R Kinoshita K Lai IC Schrenk S Bonvicini G Cinabro D McGee S Perera LP Zhou GJ Lipeles E Schmidtler M Shapiro A Sun WM Weinstein AJ Würthwein F Jaffe DE Masek G 《Physical review letters》2000,85(14):2881-2885
We report results of searches for charmless hadronic B meson decays to pseudoscalar( pi(+/-), K+/-, pi(0), or K(0)(S))-vector( rho, K(*), or omega) final states. By using 9.7x10(6) BB pairs collected with the CLEO detector, we report the first observation of B(-)--->pi(-)rho(0), B(0)-->pi(+/-)rho(-/+), and B(-)-->pi(-)omega, which are expected to be dominated by hadronic b-->u transitions. The measured branching fractions are (10.4(+3.3)(-3.4)+/-2.1)x10(-6), (27.6(+8.4)(-7.4)+/-4.2)x10(-6), and (11.3(+3.3)(-2.9)+/-1. 4)x10(-6), respectively. Branching fraction upper limits are set for all of the other decay modes investigated. 相似文献
185.
Cronin-Hennessy D Lyon AL Thorndike EH Savinov V Coan TE Fadeyev V Gao YS Maravin Y Narsky I Stroynowski R Ye J Wlodek T Artuso M Ayad R Boulahouache C Bukin K Dambasuren E Karamov S Majumder G Moneti GC Mountain R Schuh S Skwarnicki T Stone S Wang JC Wolf A Wu J Kopp S Kostin M Mahmood AH Csorna SE Danko I McLean KW Xu Z Godang R Bonvicini G Cinabro D Dubrovin M McGee S Zhou GJ Lipeles E Pappas SP Schmidtler M Shapiro A Sun WM Weinstein AJ Würthwein F Jaffe DE Masek G Paar HP Potter EM Prell S 《Physical review letters》2001,86(17):3730-3734
The CLEO experiment at the CESR collider has used 13.7 fb(-1) of data to search for the production of the Omega(0)(c) (css ground state) in e(+)e(-) collisions at square root of (s) approximately 10.6 GeV. The modes used to study the Omega(0)(c) are Omega(-)pi(+), Omega(-)pi(+)pi(0), Xi-K-pi(+)pi(+), Xi0K-pi(+), and Omega(-)pi(+)pi(+)pi(-). We observe a signal of 40.4+/-9.0(stat) events at a mass of 2694.6+/-2.6(stat)+/-1.9(syst) MeV/c(2), for all modes combined. 相似文献
186.
Mousavipour SH Fernández-Ramos A Meana-Pañeda R Martínez-Núñez E Vázquez SA Ríos MA 《The journal of physical chemistry. A》2007,111(4):719-725
Direct-dynamics canonical variational transition-state theory calculations with microcanonically optimized multidimensional transmission coefficient (CVT/muOMT) for tunneling were carried out at the MPWB1K/6-31+G(d,p) level to study the [1,7] sigmatropic hydrogen rearrangement in 7-methylocta-1,3(Z),5(Z)-triene. This compound has seven conformers, of which only one leads to products, although all of them have to be included in the theoretical treatment. The calculated CVT/muOMT rate constants are in good agreement with the available experimental data. To try to understand the role of tunneling in the hydrogen shift reaction, we have also calculated the thermal rate constants for the monodeuterated compound in the interval T = 333.2-388.2 K. This allowed us to evaluate primary kinetic isotope effects (KIEs) and make a direct comparison with the experiment. Our calculations show that both the large measured KIE and the large measured difference in the activation energies between the deuterated and root compounds are due to the quantum tunneling. The tunneling contribution to the KIE becomes noticeable only when the coupling between the reaction coordinate and the transverse modes is taken into account. Our results confirm previous experimental and theoretical works, which guessed that the obtained kinetic parameters pointed to a reaction with an important contribution due to tunneling. The above conclusion would be essentially valid for the case of the [1,7] hydrogen shift in previtamin D3 because of the similarity to the studied model system. 相似文献
187.
Homayoon Z Vázquez SA Rodríguez-Fernández R Martínez-Núñez E 《The journal of physical chemistry. A》2011,115(6):979-985
Ab initio CCSD and CCSD(T) calculations with the 6-311+G(2d,2p) and the 6-311++G(3df,3pd) basis sets were carried out to characterize the vinyl cyanide (C(3)H(3)N) dissociation channels leading to hydrogen cyanide (HCN) and its isomer hydrogen isocyanide (HNC). Our computations predict three elimination channels giving rise to HCN and another four channels leading to HNC formation. The relative HCN/HNC branching ratios as a function of internal energy of vinyl cyanide were computed using RRKM theory and the kinetic Monte Carlo method. At low internal energies (120 kcal/mol), the total HCN/HNC ratio is about 14, but at 148 kcal/mol (193 nm) this ratio becomes 1.9, in contrast with the value 124 obtained in a previous ab initio/RRKM study at 193 nm (Derecskei-Kovacs, A.; North, S. W. J. Chem. Phys.1999, 110, 2862). Moreover, our theoretical results predict a ratio of rovibrationally excited acetylene over total acetylene of 3.3, in perfect agreement with very recent experimental measurements (Wilhelm, M. J.; Nikow, M.; Letendre, L.; Dai, H.-L. J. Chem. Phys.2009, 130, 044307). 相似文献
188.
The Birnbaum‐Saunders (BS) distribution is a model that frequently appears in the statistical literature and has proved to be very versatile and efficient across a wide range of applications. However, despite the growing interest in the study of the BS distribution, quantile regression modeling has not been considered for this distribution. To fill this gap, we introduce a class of quantile regression models based on the BS distribution, which allows us to describe positive and asymmetric data when a quantile must be predicted using covariates. We use an approach based on a quantile parameterization to generate the model, permitting us to consider a similar framework to generalized linear models, providing wide flexibility. The methodology proposed includes a thorough study of theoretical properties and practical issues, such as maximum likelihood parameter estimation and diagnostic analytics based on local influence and residuals. The performance of the residuals is evaluated by simulations, whereas an illustrative example of income data is conducted using the methodology to show its potential for applications. The numerical results report an adequate performance of the approach to quantile regression, indicating that the BS distribution is a good modeling choice when dealing with data that have both positive support and asymmetry. The economic implications of our investigation are discussed in the final section. Hence, it can be a valuable addition to the tool kit of applied statisticians and econometricians. 相似文献
189.
We consider Discontinuous Galerkin approximations of two-phase, immiscible porous media flows in the global pressure/fractional flow formulation with capillary pressure. A sequential approach is used with a backward Euler step for the saturation equation, equal-order interpolation for the pressure and the saturation, and without any limiters. An accurate total velocity field is recovered from the global pressure equation to be used in the saturation equation. Numerical experiments show the advantages of the proposed reconstruction. To cite this article: A. Ern et al., C. R. Acad. Sci. Paris, Ser. I 347 (2009). 相似文献