Information entropy as a measure of the quality of a nuclear density distribution

The information entropy of a nuclear density distribution is calculated for a number of nuclei. Various phenomenological models for the density distribution using different geometry are employed. Nuclear densities calculated within various microscopic mean field approaches are also employed. It turns out that the entropy increases on going from crude phenomenological models to more sophisticated (microscopic) ones. It is concluded that the larger the information entropy, the better the quality of the nuclear density distribution. An alternative approach is also examined: the net information content i.e. the sum of information entropies in position and momentum space $S_{r}+S_{k}$. It is indicated that $S_{r}+S_{k}$ is a maximum, when the best fit to experimental data of the density and momentum distributions is attained.Comment: 12 pages, LaTex, no figures, Int. J. of Mod. Phys. E in pres

Temperature induced shell effects in deformed nuclei

The thermal evolution of the shell correction energy is investigated for deformed nuclei using Strutinsky prescription in a self-consistent relativistic mean-field framework. For temperature independent single-particle states corresponding to either spherical or deformed nuclear shapes, the shell correction energy $\Delta_{sc}$ steadily washes out with temperature. However, for states pertaining to the self-consistent thermally evolving shapes of deformed nuclei, the dual role played by the single-particle occupancies in diluting the fluctuation effects from the single-particle spectra and in driving the system towards a smaller deformation is crucial in determining $\Delta_{sc}$ at moderate temperatures. In rare earth nuclei, it is found that $\Delta_{sc}$ builds up strongly around the shape transition temperature; for lighter deformed nuclei like $^{64}Zn$ and $^{66}Zn$, this is relatively less prominent.Comment: 6 pages revtex file + 4 ps files for figures, Phys. Rev. C (in press

Climate Change, ecosystem impacts and systemic risk

This report highlights some of the vital dependencies of human societies on ecosystems, the damages that can occur from them as a result of climate change, and the steps required to better understand and characterise the systemic risks to societies that result from such climate change-driven ecosystem damages

Relativistic Mean Field Approach and the Pseudo-Spin Symmetry

Based on the Relativistic Mean Field (RMF) approach the existence of the broken pseudo-spin symmetry is investigated. Both spherical RMF and constrained deformed RMF calculations are carried out employing realistic Lagrangian parameters for spherical and for deformed sample nuclei. The quasi - degenerate pseudo-spin doublets are confirmed to exist near the fermi surface for both spherical and deformed nuclei.Comment: 9 pages RevTex, 4 p.s figures, to appear in Phys. Rev. C as R.

Types of Nonlinear Interactions between Plasmonic-Excitonic Hybrids

The unique ability of plasmonic structures to concentrate and manipulate photonic signals in deep sub-wavelength domain provides new efficient pathways to generate, guide, modulate and detect light. Due to collective oscillations exhibited by the conducting electrons of metallic nanoparticles, their local fields can be greatly enhanced at the localized surface plasmon resonance (LSPR). Hence, they offer a versatile platform, where localized surface plasmons can be tuned over a broad range of wavelengths by controlling their shape, size and material properties. It has been realized that plasmonic excitations can strengthen nonlinear optical effects in three ways. First, the coupling between the incident beam of light and surface plasmons results in a strong local confinement of the electromagnetic fields, which in turn enhances the optical response. Second, the sensitivity of plasmonic excitations toward the dielectric properties of the metal and the surrounding medium forms the basis for label-free plasmonic sensors. Finally, the excitation and relaxation dynamics of plasmonic nanostructures responds to a timescale of femtoseconds regime, thus allowing ultrafast processing of the incident optical signals. This chapter aims to discuss all the aforementioned interactions of plasmons and their excitonic hybrids in detail and also represent a glimpse of their experimental realizations

Alpha decay and proton-neutron correlations

We study the influence of proton-neutron (p-n) correlations on alpha-decay width. It is shown from the analysis of alpha Q values that the p-n correlations increase the penetration of the alpha particle through the Coulomb barrier in the treatment following Gamow's formalism, and enlarges the total alpha-decay width significantly. In particular, the isoscalar p-n interactions play an essential role in enlarging the alpha-decay width. The so-called "alpha-condensate" in Z > 84 isotopes are related to the strong p-n correlations.Comment: 5 pages, 6 figures, accepted for publication in Phys. Rev. C (R.C.

Fabrication of a graphene coated nonwoven textile for industrial applications

A cost effective electrically conductive textile for large scale applications would revolutionise numerous industries. Herein, we demonstrate a novel processing approach to produce conductive textiles for industrial applications. A conductive nonwoven textile was successfully fabricated using a simple dip coating method. The nonwoven polyester was coated with liquid crystallite graphene oxide with subsequent non-toxic chemical reduction. The process is readily scalable. The graphene coated fabric has been characterized by electron microscopy as well as by electrical, mechanical, thermal and abrasion resistance measurements. It was found that the electrical surface resistivity of the prepared polyester-graphene composite fabric was 330 Ω □-1. The electrical surface resistivity was 3 and 150 times lower than that of polypyrrole coated woven polyester fabric and graphene coated nonwoven fabrics, respectively, in previously published reports. The hybrid polyester-graphene textile prepared here should find applications in high-performance geotextiles or as heating elements

Identical Bands in Superdeformed Nuclei: A Relativistic Description

Relativistic Mean Field Theory in the rotating frame is used to describe superdeformed nuclei. Nuclear currents and the resulting spatial components of the vector meson fields are fully taken into account. Identical bands in neighboring Rare Earth nuclei are investigated and excellent agreement with recent experimental data is observed.Comment: 11 pages (Latex) and 4 figures (available upon request) TUM-ITP-Ko93/

Covariant response theory beyond RPA and its application

The covariant particle-vibration coupling model within the time blocking approximation is employed to supplement the Relativistic Random Phase Approximation (RRPA) with coupling to collective vibrations. The Bethe-Salpeter equation in the particle-hole channel with an energy dependent residual particle-hole (p-h) interaction is formulated and solved in the shell-model Dirac basis as well as in the momentum space. The same set of the coupling constants generates the Dirac-Hartree single-particle spectrum, the static part of the residual p-h interaction and the particle-phonon coupling amplitudes. This approach is applied to quantitative description of damping phenomenon in even-even spherical nuclei with closed shells $^{208}$Pb and $^{132}$Sn. Since the phonon coupling enriches the RRPA spectrum with a multitude of ph$\otimes$phonon states a noticeable fragmentation of giant monopole and dipole resonances is obtained in the examined nuclei. The results are compared with experimental data and with results of the non-relativistic approach.Comment: 12 pages, 4 figures, Proceedings of the NSRT06 Conferenc

A Whole-Genome RNA Interference Screen Reveals a Role for Spry2 in Insulin Transcription and the Unfolded Protein Response.

Insulin production by the pancreatic β-cell is required for normal glucose homeostasis. While key transcription factors that bind to the insulin promoter are known, relatively little is known about the upstream regulators of insulin transcription. Using a whole-genome RNA interference screen, we uncovered 26 novel regulators of insulin transcription that regulate diverse processes including oxidative phosphorylation, vesicle traffic, and the unfolded protein response (UPR). We focused on Spry2-a gene implicated in human type 2 diabetes by genome-wide association studies but without a clear connection to glucose homeostasis. We showed that Spry2 is a novel UPR target and its upregulation is dependent on PERK. Knockdown of Spry2 resulted in reduced expression of Serca2, reduced endoplasmic reticulum calcium levels, and induction of the UPR. Spry2 deletion in the adult mouse β-cell caused hyperglycemia and hypoinsulinemia. Our study greatly expands the compendium of insulin promoter regulators and demonstrates a novel β-cell link between Spry2 and human diabetes