Proton Decay from Excited States in Spherical Nuclei

Based on a single particle model which describes the time evolution of the wave function during tunneling across a one dimensional potential barrier we study the proton decay of $^{208}$Pb from excited states with non-vanishing angular momentum $\ell$. Several quantities of interest in this process like the decay rate $\lambda$, the period of oscillation $T_{osc}$, the transient time $t_{tr}$, the tunneling time $t_{tun}$ and the average value of the proton packet position $r_{av}$ are computed and compared with the WKB results.Comment: 12 pages, 4 figure

FISSION DYNAMICS WITH MICROSCOPIC LEVEL DENSITIES

We present a consistent framework for treating the energy and angularmomentum dependence of the shape evolution in the nuclear fission. It combines microscopically calculated level densities with the Metropolis-walk method, has no new parameters, and can elucidate the energy-dependent influence of pairing and shell effects on the dynamics of warm nuclei

Oral Cytokine Levels Are More Linked to Levels of Plasma and Oral HIV-1 RNA Than to CD4+ T-Cell Counts in People With HIV.

BackgroundWe determined the levels of 11 soluble immune mediators in oral washings of AIDS Clinical Trials Group A5254 participants with varying degrees of plasma viremia and CD4 T-cell counts to characterize the mucosal immune response at different stages of HIV-1 infection.MethodsA5254 was a multicenter, cross-sectional study in people with HIV (PWH) recruited into 4 strata based on CD4 count and levels of plasma viremia: stratum (St) A: CD4 ≤200 cells/mm3, HIV-1 RNA (viral load [VL]) >1000 cps/mL; St B: CD4 ≤200, VL ≤1000; St C: CD4 >200, VL >1000; St D: CD4 >200, VL ≤1000. Oral/throat washings were obtained from all participants. Soluble markers were tested in oral/throat washings using a multibead fluorescent platform and were compared across strata. Linear regression was used to determine the associations between cytokines and HIV-1 in plasma and oral fluid.ResultsSt A participants had higher levels of interleukin (IL)-1β, IL-6, IL-17, tumor necrosis factor alpha (TNFα), and interferon gamma (IFNγ) compared with St B and D (P = .02; P < .0001) but were not different from St C. IL-8, IL-10, and IL-12 were elevated in St A compared with the other 3 strata (P = .046; P < .0001). Linear regression demonstrated that oral HIV-1 levels were associated with IL-1β, IL-6, IL-8, and TNFα production (R > .40; P < .001) when controlling for CD4 count and opportunistic infections.ConclusionsOur results show that high levels of oral HIV-1, rather than low CD4 counts, were linked to the production of oral immune mediators. Participants with AIDS and uncontrolled viremia demonstrated higher levels of pro- and anti-inflammatory soluble immune mediators compared with participants with lower HIV-1 RNA. The interplay of HIV-1 and these immune mediators could be important in the oral health of PWH

The ab initio no-core shell model

This contribution reviews a number of applications of the ab initio no-core shell model (NCSM) within nuclear physics and beyond. We will highlight a nuclear-structure study of the A = 12 isobar using a chiral NN + 3NF interaction. In the spirit of this workshop we will also mention the new development of the NCSM formalism to describe open channels and to approach the problem of nuclear reactions. Finally, we will illustrate the universality of the many-body problem by presenting the recent adaptation of the NCSM effective-interaction approach to study the many-boson problem in an external trapping potential with short-range interactions.Comment: 4 pages. Article based on the presentation by C. Forssen at the Fifth Workshop on Critical Stability, Erice, Sicily. Published in Few-Body System

Tests and applications of self-consistent cranking in the interacting boson model

The self-consistent cranking method is tested by comparing the cranking calculations in the interacting boson model with the exact results obtained from the SU(3) and O(6) dynamical symmetries and from numerical diagonalization. The method is used to study the spin dependence of shape variables in the $sd$ and $sdg$ boson models. When realistic sets of parameters are used, both models lead to similar results: axial shape is retained with increasing cranking frequency while fluctuations in the shape variable $\gamma$ are slightly reduced.Comment: 9 pages, 3 ps figures, Revte

Energy averages and fluctuations in the decay out of superdeformed bands

We derive analytic formulae for the energy average (including the energy average of the fluctuation contribution) and variance of the intraband decay intensity of a superdeformed band. Our results may be expressed in terms of three dimensionless variables: $\Gamma^{\downarrow}/\Gamma_S$, $\Gamma_N/d$, and $\Gamma_N/(\Gamma_S+\Gamma^{\downarrow})$. Here $\Gamma^{\downarrow}$ is the spreading width for the mixing of a superdeformed (SD) state $|0>$ with the normally deformed (ND) states $|Q>$ whose spin is the same as $|0>$'s. The $|Q>$ have mean level spacing $d$ and mean electromagnetic decay width $\Gamma_N$ whilst $|0>$ has electromagnetic decay width $\Gamma_S$. The average decay intensity may be expressed solely in terms of the variables $\Gamma^{\downarrow}/\Gamma_S$ and $\Gamma_N/d$ or, analogously to statistical nuclear reaction theory, in terms of the transmission coefficients $T_0(E)$ and $T_N$ describing transmission from the $|Q>$ to the SD band via $|0\angle$ and to lower ND states. The variance of the decay intensity, in analogy with Ericson's theory of cross section fluctuations depends on an additional variable, the correlation length \Gamma_N/(\Gamma_S+\Gamma^{\downarrow})=\frac{d}{2\pi}T_N/(\Gamma_S+\Gamma^{\d ownarrow}). This suggests that analysis of an experimentally obtained variance could yield the mean level spacing $d$ as does analysis of the cross section autocorrelation function in compound nuclear reactions. We compare our results with those of Gu and Weidenm\"uller.Comment: revtex4, 14 pages, 4 figures, to appear in Physical Review

A measure of majorisation emerging from single-shot statistical mechanics

The use of the von Neumann entropy in formulating the laws of thermodynamics has recently been challenged. It is associated with the average work whereas the work guaranteed to be extracted in any single run of an experiment is the more interesting quantity in general. We show that an expression that quantifies majorisation determines the optimal guaranteed work. We argue it should therefore be the central quantity of statistical mechanics, rather than the von Neumann entropy. In the limit of many identical and independent subsystems (asymptotic i.i.d) the von Neumann entropy expressions are recovered but in the non-equilbrium regime the optimal guaranteed work can be radically different to the optimal average. Moreover our measure of majorisation governs which evolutions can be realized via thermal interactions, whereas the nondecrease of the von Neumann entropy is not sufficiently restrictive. Our results are inspired by single-shot information theory.Comment: 54 pages (15+39), 9 figures. Changed title / changed presentation, same main results / added minor result on pure bipartite state entanglement (appendix G) / near to published versio

Mapping the proton drip line from Z=31 to Z=49

The structure of proton drip line nuclei in the 60 < A < 100 mass range is studied with the Relativistic Hartree Bogoliubov (RHB) model. For the elements which determine the astrophysical rapid proton capture process path, the RHB model predicts the location of the proton drip-line, the ground-state quadrupole deformations and one-proton separation energies at and beyond the drip-line. The results of the present theoretical investigation are compared with available experimental data. For possible odd-Z ground state proton emitters, the calculated deformed single-particle orbitals occupied by the odd valence proton and the corresponding spectroscopic factors are compared with predictions of the macroscopic-microscopic mass model.Comment: 20 pages, LaTeX, 6 eps figs, submitted to Nucl. Phys.

Measuring movement fluency during the sit-to-walk task

Restoring movement fluency is a key focus for physical rehabilitation; it's measurement, however, lacks objectivity. The purpose of this study was to find whether measurable movement fluency variables differed between groups of adults with different movement abilities whilst performing the sit-to-walk (STW) movement. The movement fluency variables were: (1) hesitation during movement (reduction in forward velocity of the centre of mass; CoM), (2) coordination (percentage of temporal overlap of joint rotations) and (3) smoothness (number of inflections in the CoM jerk signal)

First principles calculation of point defects and mobility degradation in bulk AlSb for radiation detection application

The development of high resolution, room temperature semiconductor radiation detectors requires the introduction of materials with increased carrier mobility-lifetime ({mu}{tau}) product, while having a band gap in the 1.4-2.2 eV range. AlSb is a promising material for this application. However, systematic improvements in the material quality are necessary to achieve an adequate {mu}{tau} product. We are using a combination of simulation and experiment to develop a fundamental understanding of the factors which affect detector material quality. First principles calculations are used to study the microscopic mechanisms of mobility degradation from point defects and to calculate the intrinsic limit of mobility from phonon scattering. We use density functional theory (DFT) to calculate the formation energies of native and impurity point defects, to determine their equilibrium concentrations as a function of temperature and charge state. Perturbation theory via the Born approximation is coupled with Boltzmann transport theory to calculate the contribution toward mobility degradation of each type of point defect, using DFT-computed carrier scattering rates. A comparison is made to measured carrier concentrations and mobilities from AlSb crystals grown in our lab. We find our predictions in good quantitative agreement with experiment, allowing optimized annealing conditions to be deduced. A major result is the determination of oxygen impurity as a severe mobility killer, despite the ability of oxygen to compensation dope AlSb and reduce the net carrier concentration. In this case, increased resistivity is not a good indicator of improved material performance, due to the concomitant sharp reduction in {mu}{tau}