Scattering Wave Functions at Bound State Poles

The normalisation relation between the bound and scattering S-state wave functions, extrapolated to the bound state pole, is derived from the Schroedinger equation. It is shown that, unlike previous work, the result does not depend on the details of the potential through the corresponding Jost function but is given uniquely in terms of the binding energy. The generalisations to higher partial waves and one-dimensional scattering are given.Comment: 15 pages Latex. No graph

Racial/Ethnic Differences in Bone Mineral Density of Young Adults

An estimated 1.5 million people suffer a bone disease-related fracture every year. Most work investigating bone mineral density (BMD) focuses on post-menopausal females but a report from the Surgeon General in 2004 stated that of particular concern are men, racial and ethnic minorities, poor individuals, individuals with disabilities, and individuals living in rural areas. The purpose of this study was to examine the racial/ethnic differences in bone mineral density of young adults and to investigate any correlations with variables suggested to influence BMD. BMD was assessed at a younger age than most studies based on the assumption that osteoporosis is a pediatric disorder that manifests in old age. Whole-body BMD, percent body fat (BF), fat mass (FM), and lean mass (LM) of 103 college-aged Blacks, Whites, and Hispanics (18 – 34 years of age) were measured using a Lunar Prodigy Dual Energy X-ray Absorptiometry (DEXA). Blacks and Whites were taller than Hispanics. Blacks had higher BMD than Whites and Hispanics. Blacks and Whites had higher t-scores than Hispanics. Weight and LM correlated with BMD for all three groups. Height correlated with BMD for Blacks only. FM correlated with BMD for Hispanics only. In conclusion, BMD is suggested to be higher in Blacks than Whites and Hispanics. LM is suggested to be an important component of bone health. It is important to stress resistance training for building and maintaining bone health throughout life

Exact Eignstates for Trapped Weakly Interacting Bosons in Two Dimensions

A system of N two-dimensional weakly interacting bosons in a harmonic trap is considered. When the two-particle potential is a delta function Smith and Wilkin have analytically proved that the elementary symmetric polynomials of particle coordinates measured from the center of mass are exact eigenstates. In this study, we point out that their proof works equally well for an arbitrary two-particle potential which possesses the translational and rotational symmetries. We find that the interaction energy associated with the eigenstate with angular momentum L is equal to aN(N-1)/2+(b-a)NL/2, where a and b are the interaction energies of two bosons in the lowest-energy one-particle state with zero and one unit of angular momentum, respectively. Additionally, we study briefly the case of attractive quartic interactions. We prove rigorously that the lowest-energy state is the one in which all angular momentum is carried by the center of mass motion.Comment: 4 pages, minor changes made, to appear in PRA Brie

On the criterion for Bose-Einstein condensation for particles in traps

We consider the criterion for Bose condensation for particles in a harmonic trap. For a fixed angular momentum, the lowest energy state for a cloud of bosons with attractive interactions is the ground state of the cloud with all the angular momentum in the center-of-mass motion, and the one-particle reduced density matrix generally does not have a single large eigenvalue, but a number of them, suggesting that the state is an example of a fragmented condensate (Wilkin, Gunn, and Smith, Phys. Rev. Lett. 80, 2265 (1998)). We show that a convenient way to describe correlations in the system is by defining an internal one-particle reduced density matrix, in which the center-of-mass motion is eliminated, and that this has a single eigenvalue equal to the number of particles for the problem considered here. Our considerations indicate that care is necessary in formulating a criterion for Bose-Einstein condensation.Comment: 2 pages, RevTex, Submitted to Phys. Rev.

Yrast line for weakly interacting trapped bosons

We compute numerically the yrast line for harmonically trapped boson systems with a weak repulsive contact interaction, studying the transition to a vortex state as the angular momentum L increases and approaches N, the number of bosons. The L=N eigenstate is indeed dominated by particles with unit angular momentum, but the state has other significant components beyond the pure vortex configuration. There is a smooth crossover between low and high L with no indication of a quantum phase transition. Most strikingly, the energy and wave function appear to be analytical functions of L over the entire range 2 < L < N. We confirm the structure of low-L states proposed by Mottelson, as mainly single-particle excitations with two or three units of angular momentum.Comment: 9 pages, 3 EPS-figures, uses psfig.st

Near-Threshold Production of omega Mesons in the pp -> pp omega Reaction

The total cross section for omega production in the pp -> pp omega reaction has been measured at five c.m. excess energies from 3.8 to 30 MeV. The energy dependence is easily understood in terms of a strong proton-proton final state interaction combined with a smearing over the width of the state. The ratio of near-threshold phi and omega production is consistent with the predictions of a one-pion-exchange model and the degree of violation of the OZI rule is similar to that found in the pi-p -> n omega/phi reactions.Comment: Report in LaTeX2e. 12 pages with 2 eps figure

Within-population variation in prevalence and lineage distribution of avian malaria in blue tits, Cyanistes caeruleus

The development of molecular genetic screening techniques for avian blood parasites has revealed many novel aspects of their ecology, including greatly elevated diversity and complex host–parasite relationships. Many previous studies of malaria in birds have treated single study populations as spatially homogeneous with respect to the likelihood of transmission of malaria to hosts, and we have very little idea whether any spatial heterogeneity influences different malaria lineages similarly. Here, we report an analysis of variation in the prevalence and cytochrome b lineage distribution of avian malaria infection with respect to environmental and host factors, and their interactions, in a single blue tit (Cyanistes caeruleus) population. Of 11 Plasmodium and Haemoproteus cytochrome b lineages found in 997 breeding individuals, the three most numerous (pSGS1, pTURDUS1 and pBT7) were considered separately, in addition to analyses of all avian malaria lineages pooled. Our analyses revealed marked spatial differences in the prevalence and distribution of these lineages, with local prevalence of malaria within the population ranging from over 60% to less than 10%. In addition, we found several more complex patterns of prevalence with respect to local landscape features, host state, parasite genotype, and their interactions. We discuss the implications of such heterogeneity in parasite infection at a local scale for the study of the ecology and evolution of infectious diseases in natural populations. The increased resolution afforded by the combination of molecular genetic and geographical information systems (GIS) tools has the potential to provide many insights into the epidemiology, evolution and ecology of these parasites in the future

Topological Defects in the Abrikosov Lattice of Vortices in Type-II Superconductors

The free energy costs for various defects within an Abrikosov lattice of vortices are calculated using the lowest Landau level approximation (LLL). Defect solutions with boundary conditions for lines to meet at a point (crossing defect) and for lines to twist around each other (braid defect) are sought for 2, 3, 6, and 12 lines. Many results have been unexpected, including the nonexistence of a stable two- or three-line braid. This, and the high energy cost found for a six-line braid lead us to propose that the equilibrium vortex state is not entangled below the irreversibility line of the high-$T_c$ superconductors or in a large part of the vortex-liquid phase above this line. Also, the solution for an infinite straight screw dislocation is found, and used to give a limiting form for the free energy cost of very large braids. This depends on the area enclosed by the braid as well as its perimeter length.Comment: 30 pages, 17 Encapsulated PostScript figures, uses Revtex (with epsf

The pd→3HΛK+pd\to ^3H_\Lambda K^+ reaction cross section

The one- and two-step mechanisms of the $pd\to ^3H_\Lambda K^+$ reaction in the range of incident proton kinetic energy 1.13-3.0 GeV have been investigated. A remarkable peculiarity of the two-step mechanism which incorporates subprocesses $pp\to d\pi ^+$ and $\pi^+n\to K^+\Lambda$ is the so called velocity matching providing the presence of all intermediate particles nearly to the on-mass-shell. The differential cross section has been calculated using a realistic model for the hypertritium $^3H_\Lambda$ wave function. The maximum value of the cross section is estimated as $\sim$1nb/sr. The contribution of the one-step mechanism with the elementary process $pN\to NK\Lambda$ into the cross section has been found to be two - three orders of magnitude smaller in comparison with the two-step mechanism.Comment: 10 pages, Latex, 3 Postscript figure

Dynamics of 1S0^{1}S_0 diproton formation in the pd→{pp}snpd\to \{pp\}_sn and pN→{pp}sπpN\to \{pp\}_s\pi reactions in the GeV region

Mechanisms for the production of $^1S_0$ diproton pairs, ${pp}_s$, in the $pd\to {pp}_s n$ reaction are studied at proton beam energies 0.5 -- 2 GeV in kinematics similar to those of backward elastic $pd$ scattering. This reaction provides valuable information on the short-range $NN$ and $pd$ interactions that is complementary to that investigated in the well known $pd\to dp$ and $dp\to p(0^\circ)X$ processes. The $pd\to {pp}_sn$ reaction is related to the subprocesses $\pi^0 d\to pn$ and $pN\to {pp}_s \pi$ using two different one--pion--exchange (OPE) diagrams. Within both these models a reasonable agreement could be obtained with the data below 1GeV. The similar energy dependence of the $pd\to\{pp\}_s n$ and $pd\to dp$ cross sections and the small ratio of about 1.5% in the production of $\{pp\}_s$ to deuteron final states follow naturally within the OPE models.Comment: 10 pages, 7 figures, Late