Surface-peaked effective mass in the nuclear energy density functional and its influence on single-particle spectra

Calculations for infinite nuclear matter with realistic nucleon-nucleon interactions suggest that the isoscalar effective mass of a nucleon at the saturation density, m*/m, equals 0.8 +/- 0.1. This result is at variance with empirical data on the level density in finite nuclei, which are consistent with m*/m ~ 1. Ma and Wambach suggested that these two contradicting results may be reconciled within a single theoretical framework by assuming a radial-dependent effective mass, peaked at the nuclear surface. The aim of this exploratory work is to investigate this idea within the density functional theory by using a Skyrme-type local functional enriched with new terms, $\tau (\mathbf{\nabla}\rho)^2$ and $\tau\frac{d\rho}{dr}$, where $\tau$ and $\rho$ denote the kinetic and particle densities, respectively. We show that each of these terms can give rise to a surface peak in the effective mass, but of a limited height. We investigate the influence of the radial profile of the effective mass on the spin-orbit splittings and centroids. In particular, we demonstrate that the $\tau \frac{d\rho}{dr}$ term quenches the 1f5/2-1f7/2 splitting in 40Ca, which is strongly overestimated within conventional Skyrme parametrizations.Comment: 8 pages, 8 figures, submitted to Phys. Rev.

Spin-orbit and tensor mean-field effects on spin-orbit splitting including self-consistent core polarizations

A new strategy of fitting the coupling constants of the nuclear energy density functional is proposed, which shifts attention from ground-state bulk to single-particle properties. The latter are analyzed in terms of the bare single-particle energies and mass, shape, and spin core-polarization effects. Fit of the isoscalar spin-orbit and both isoscalar and isovector tensor coupling constants directly to the f5/2-f7/2 spin-orbit splittings in 40Ca, 56Ni, and 48Ca is proposed as a practical realization of this new programme. It is shown that this fit requires drastic changes in the isoscalar spin-orbit strength and the tensor coupling constants as compared to the commonly accepted values but it considerably and systematically improves basic single-particle properties including spin-orbit splittings and magic-gap energies. Impact of these changes on nuclear binding energies is also discussed.Comment: 15 pages, 7 figures, submitted to Physical Review

Badger: Complexity Analysis with Fuzzing and Symbolic Execution

Hybrid testing approaches that involve fuzz testing and symbolic execution have shown promising results in achieving high code coverage, uncovering subtle errors and vulnerabilities in a variety of software applications. In this paper we describe Badger - a new hybrid approach for complexity analysis, with the goal of discovering vulnerabilities which occur when the worst-case time or space complexity of an application is significantly higher than the average case. Badger uses fuzz testing to generate a diverse set of inputs that aim to increase not only coverage but also a resource-related cost associated with each path. Since fuzzing may fail to execute deep program paths due to its limited knowledge about the conditions that influence these paths, we complement the analysis with a symbolic execution, which is also customized to search for paths that increase the resource-related cost. Symbolic execution is particularly good at generating inputs that satisfy various program conditions but by itself suffers from path explosion. Therefore, Badger uses fuzzing and symbolic execution in tandem, to leverage their benefits and overcome their weaknesses. We implemented our approach for the analysis of Java programs, based on Kelinci and Symbolic PathFinder. We evaluated Badger on Java applications, showing that our approach is significantly faster in generating worst-case executions compared to fuzzing or symbolic execution on their own

Hidden asymmetry and forward-backward correlations

A model-independent method of studying the forward-backward correlations in symmetric high energy processes is developed. The method allows a systematic study of properties of various particle sources and to uncover asymmetric structures hidden in symmetric hadron-hadron and nucleus-nucleus inelastic reactions.Comment: 11 pages, no figure

Intracellular zinc depletion induces caspase activation and p21Waf1/Cip1 cleavage in human epithelial cell lines

To better understand the mechanisms by which zinc deficiency induces epithelial cell death, studies were done of the effects of intracellular zinc depletion induced by the zinc chelator TPEN on apoptosis-related events in human malignant epithelial cell lines LIM1215 (colonic), NCI-H292 (bronchial), and A549 (alveolar type II). In TPEN-treated cells, depletion of zinc was followed by activation of caspase-3 (as demonstrated by enzymatic assay and Western blotting), DNA fragmentation, and morphologic changes. Increase in caspase-3 activity began 1–2 h after addition of TPEN, suggesting that zinc may suppress a step just before the activation of this caspase. Caspase-6, a mediator of caspase-3 processing, also increased, but later than caspase-3. Effects of TPEN on apoptosis were completely prevented by exogenous ZnSO4 and partially prevented by peptide caspase inhibitors. A critical substrate of caspase-3 may be the cell cycle regulator p21Waf1/Cip1, which was rapidly cleaved in TPEN-treated cells to a 15-kDa fragment before further degradation.F. Chai, A. Q. Truong-Tran, A. Evdokiou, G. P. Young and P. D. Zalewsk

Four-photon interference: a realizable experiment to demonstrate violation of EPR postulates for perfect correlations

Bell's theorem reveals contradictions between the predictions of quantum mechanics and the EPR postulates for a pair of particles only in situations involving imperfect statistical correlations. However, with three or more particles, contradictions emerge even for perfect correlations. We describe an experiment which can be realized in the laboratory, using four-photon entangled states generated by parametric down-conversion, to demonstrate this contradiction at the level of perfect correlations.Comment: publishe

Global nuclear structure effects of tensor interaction

A direct fit of the isoscalar spin-orbit (SO) and both isoscalar and isovector tensor coupling constants to the f5/2-f7/2 SO splittings in 40Ca, 56Ni, and 48Ca nuclei requires a drastic reduction of the isoscalar SO strength and strong attractive tensor coupling constants. The aim of this work is to address further consequences of these strong attractive tensor and weak SO fields on binding energies, nuclear deformability, and high-spin states. In particular, we show that contribution to the nuclear binding energy due to the tensor field shows generic magic structure with tensorial magic numbers at N(Z)=14, 32, 56, or 90 corresponding to the maximum spin-asymmetries in 1d5/2, 1f7/2-2p3/2, 1g9/2-2d5/2 and 1h11/2-2f7/2 single-particle configurations and that these numbers are smeared out by pairing correlations and deformation effects. We also examine the consequences of strong attractive tensor fields and weak SO interaction on nuclear stability at the drip lines, in particular close to the tensorial doubly magic nuclei and discuss the possibility of an entirely new tensor-force driven deformation effect.Comment: replaced with published versio