A parametric approach to correspondence analysis

We compare correspondence analysis (CA) and the alternative approach using Hellinger distance (HD), for representing categorical data in a contingency table. As both methods may be appropriate, we introduce a parameter and define a generalized version of correspondence analysis (GCA) which contains CA and HD as particular cases. Comparison with alternative approaches are performed. We propose a coefficient which globally measures the similarity between CA and GCA, which can be decomposed into several components, one component for each principal dimension, indicating the contribution of the dimensions on the difference between both representations. Two criteria for choosing the best value of the parameter are proposed.     

Linear Key Predistribution Schemes

In a key predistribution scheme, some secret information is distributed among a set of users. For a given family of privileged groups, this secret information must enable every user in a privileged group to compute a common key associated with that group. Besides, this common key must remain unknown to some specified coalitions of users outside the privileged group. We present in this paper a new model, based on linear algebraic techniques, for the design of key predistribution schemes that unifies all previous proposals. This new model provides a common mathematical formulation and a better understanding of key predistribution schemes. Two new families of key predistribution schemes that are obtained by using this model are presented. Those families provide, for some specification structures, schemes that have better information rates than the ones given in previous proposals or fit in situations that have not been considered before.     

Lattice dynamics of the transition metal pentatellurides ZrTe5 and HfTe5

Fresh Raman data collected from the (001) face of a ZrTe₅ single crystal and from polycrystalline powders of ZrTe₅ and HfTe₅ are presented. A simple model assuming only central interactions between nearest neighbour atoms is used for lattice dynamical calculations at $\text{k}\text{=}\text{0}$. The model accounts for the observations and places emphasis on the virtually lacking dynamical coupling between the two basic structural units in these pentatellurides [trigonal-prismatic (MTe₃)_n rods and zig-zag (Te₂)₂ chains].     

Spin depolarization in Ni and Ce

Spin polarized electrons produced by polarized light in a Ge single crystal are depolarized by thin layers of Ni and Ce deposited on the surface of the sample. The mean free path for spin-exchange scattering is found to be (12.5 ± 1.5) Å in Ni and (3.2 ± 1) Å in Ce. The depolarization by Ce is found to be identical at 300 and 4 K. It is concluded that the occupancy of the 4? shell of the Ce atoms is similar at both temperatures.     

Some homoclinic phenomena in the three-body problem

We prove the existence of transversal homoclinic points in the collinear three-body problem, restricted and general, and in the planar circular restricted three-body problem. As a consequence the shift of Bernoulli is proved to be included as a subsystem of a suitable section of the flow for the three cases studied. Then the existence of all the possible types of final evolution follows.     

Collective mode dispersions of organic chain compounds

We investigate the collective mode dispersions for the tight-binding dielectric matrix with two one-dimensional electron bands per donor and acceptor chains, and the three-dimensional long-range Coulomb electron-electron interaction within the random phase approximation. The hybridized collective modes are the result of the strong coupling between the intraband plasmon and the interband dipolar modes due to strong dipole Coulomb interactions. Our calculations show the existence of the low-energy renormalized plasmon mode above the electron-hole quasi-continuum in the long wavelength limit. The obtained modes are brought into correspondence with the optical data of quasi-one-dimensional organic conductor tetrathiafulvalene-tetracyanoquinodimethane (TTF-TCNQ). Namely, the renormalized plasmon and the dipolar mode are assigned to the observed excitations at respective energy scales of roughly 10 meV and 0.75 eV, explaining why lower excitation is eliminated while higher excitation persists below the temperature of the Peierls phase transition.     

Observation of B(+)-->phiphiK(+) and evidence for B(0)-->phiphiK(0) below eta(c) threshold

We report measurements of the decays B(+)-->phiphiK(+) and B(0)-->phiphiK(0) using a sample of 231 x 10(6) BB pairs collected with the BABAR detector at the PEP-II asymmetric-energy B factory at the Stanford Linear Accelerator Center. The branching fractions are measured to be B(B(+)-->phiphiK(+))=(7.5+/-1.0(stat)+/-0.7(syst)) x 10(-6) and B(B(0)-->phiphiK(0))=(4.1(-1.4)(+1.7)(stat)+/-0.4(syst)) x 10(-6) for a phiphi invariant mass below 2.85 GeV/c(2).     

Observation of an excited charm baryon Omega c* decaying to Omega c0gamma

We report the first observation of an excited singly charmed baryon Omega c* (css) in the radiative decay Omega c0gamma, where the Omega c0 baryon is reconstructed in the decays to the final states Omega(-)pi+, Omega(-)pi+pi0, Omega(-)pi+pi(-)pi+, and Xi(-)K(-)pi+pi+. This analysis is performed using a data set of 230.7 fb(-1) collected by the BABAR detector at the PEP-II asymmetric-energy B factory at the Stanford Linear Accelerator Center. The mass difference between the Omega c* and the Omega c0 baryons is measured to be 70.8+/-1.0(stat)+/-1.1(syst) MeV/c2. We also measure the ratio of inclusive production cross sections of Omega c* and Omega c0 in e+e(-) annihilation.     

Measurement of the B-->pi l nu branching fraction and determination of absolute value of V(ub) with tagged B mesons

We report a measurement of the B-->pi l nu branching fraction based on 211 fb(-1) of data collected with the BABAR detector. We use samples of B0 and B+ mesons tagged by a second B meson reconstructed in a semileptonic or hadronic decay and combine the results assuming isospin symmetry to obtain B(B(0)-->pi- l+ nu) = (1.33+/-0.17stat+/-0.11syst) x 10(-4). We determine the magnitude of the Cabibbo-Kobayashi-Maskawa matrix element absolute value V(ub) by combining the partial branching fractions measured in ranges of the momentum transfer squared and theoretical calculations of the form factor. Using a recent lattice QCD calculation, we find absolute value V(ub) = (4.5+/-0.5stat+/-0.3syst(+0.7) -0.5FF x 10(-3), where the last error is due to the normalization of the form factor.