Nearly Mass-Degenerate Majorana Neutrinos: Double Beta Decay and Neutrino Oscillations

Assuming equal tree-level Majorana masses for the standard-model neutrinos, either from the canonical seesaw mechanism or from a heavy scalar triplet, I discuss how their radiative splitting may be relevant to neutrinoless double beta decay and neutrino oscillations.Comment: 12 pages, including 4 figures, talk at NANP9

Complete relativistic equation of state for neutron stars

We construct the equation of state (EOS) in a wide density range for neutron stars using the relativistic mean field theory. The properties of neutron star matter with both uniform and non-uniform distributions are studied consistently. The inclusion of hyperons considerably softens the EOS at high densities. The Thomas-Fermi approximation is used to describe the non-uniform matter, which is composed of a lattice of heavy nuclei. The phase transition from uniform matter to non-uniform matter occurs around $0.06 \rm{fm^{-3}}$, and the free neutrons drip out of nuclei at about $2.4 \times 10^{-4}\ \rm{fm^{-3}}$. We apply the resulting EOS to investigate the neutron star properties such as maximum mass and composition of neutron stars.Comment: 23 pages, REVTeX, 9 ps figures, to appear in Phys. Rev.

Spiral Chain O4 Form of Dense Oxygen

Oxygen is in many ways a unique element: the only known diatomic molecular magnet and the capability of stabilization of the hitherto unexpected O8 cluster structure in its solid form at high pressure. Molecular dissociations upon compression as one of the fundamental problems were reported for other diatomic solids (e.g., H2, I2, Br2, and N2), but it remains elusive for solid oxygen, making oxygen an intractable system. We here report the theoretical prediction on the dissociation of molecular oxygen into a polymeric spiral chain O4 structure (\theta-O4) by using first-principles calypso method on crystal structure prediction. The \theta-O4 stabilizes above 2 TPa and has been observed as the third high pressure phase of sulfur (S-III). We find that the molecular O8 phase remains extremely stable in a large pressure range of 0.008 - 2 TPa, whose breakdown is driven by the pressure-induced instability of a transverse acoustic phonon mode at zone boundary, leading to the ultimate formation of \theta-O4. Remarkably, stabilization of \theta-O4 turns oxygen from a superconductor into an insulator with a wide band gap (approximately 5.9 eV) originating from the sp3-like hybridized orbitals of oxygen and the localization of valence electrons. (This is a pre-print version of the following article: Li Zhu et al, Spiral chain O4 form of dense oxygen, Proc. Natl. Acad. Sci. U.S.A. (2011), doi: 10.1073/pnas.1119375109, which has been published online at http://www.pnas.org/content/early/2011/12/27/1119375109 .)Comment: 13 apages, 3 figure

Low-Temperature Solution-Processed Electron Transport Layers for Inverted Polymer Solar Cells

© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, WeinheimProcessing temperature is highlighted as a convenient means of controlling the optical and charge transport properties of solution processed electron transport layers (ETLs) in inverted polymer solar cells. Using the well-studied active layer – poly(3-hexylthiophene-2,5-diyl):indene-C60 bisadduct – the influence of ETL processing temperatures from 25 to 450 °C is shown, reporting the role of crystallinity, structure, charge transport, and Fermi level (EF) on numerous device performance characteristics. It has been determined that an exceptionally low temperature processed ETL (110 °C) increases device power conversion efficiency by a factor greater than 50% compared with a high temperature (450 °C) processed ETL. Modulations in device series and shunt resistance, induced by changes in the ETL transport properties, are observed in parallel to significant changes in device open circuit voltage attributed to changes on the EF of the ETLs. This work highlights the importance of interlayer control in multilayer photovoltaic devices and presents a convenient material compatible with future flexible and roll-to-roll processes

Radio Polarization Observations of the Snail: A Crushed Pulsar Wind Nebula in G327.1-1.1 with a Highly Ordered Magnetic Field

Pulsar wind nebulae (PWNe) are suggested to be acceleration sites of cosmic rays in the Galaxy. While the magnetic field plays an important role in the acceleration process, previous observations of magnetic field configurations of PWNe are rare, particularly for evolved systems. We present a radio polarization study of the "Snail" PWN inside the supernova remnant G327.1-1.1 using the Australia Telescope Compact Array. This PWN is believed to have been recently crushed by the supernova (SN) reverse shock. The radio morphology is composed of a main circular body with a finger-like protrusion. We detected a strong linear polarization signal from the emission, which reflects a highly ordered magnetic field in the PWN and is in contrast to the turbulent environment with a tangled magnetic field generally expected from hydrodynamical simulations. This could suggest that the characteristic turbulence scale is larger than the radio beam size. We built a toy model to explore this possibility, and found that a simulated PWN with a turbulence scale of about one-eighth to one-sixth of the nebula radius and a pulsar wind filling factor of 50--75% provides the best match to observations. This implies substantial mixing between the SN ejecta and pulsar wind material in this system.Comment: 13 pages, 10 figures, Accepted for publication in Ap

Fluorescence studies of the binding of amphiphilic amines with phospholipids.

The binding characteristics of several amine drugs with dispersed phospholipids (phosphatidylcholine, phosphatidylserine, and phosphatidylglycerol) have been studied using the fluorometric method and 1-anilino-8-naphthalene sulfonate and 1,6 diphenyl-1,3,5-hexatriene as fluorescence probes. The results show that amphiphilic amines, such as chlorphentermine, interact with phospholipids via both ionic and hydrophobic forces. The ionic interaction, which occurs between the protonated amine group of the drug and the phosphate oxygen of the lipid, changes the amphiphilic characteristics of the lipid by reducing the number of negative charges on the lipid vesicles, and inhibits the Ca2+-dependent lipid hydrolysis by blocking the Ca2+ binding sites on the lipid vesicles. The hydrophobic interaction, which involves the nonpolar moieties of the drug and the lipid, is of primary importance to the overall drug-lipid binding stability. Drugs without a strong hydrophobic moiety, such as dopamine, do not interact with phospholipids

Δ\Delta-scaling and Information Entropy in Ultra-Relativistic Nucleus-Nucleus Collisions

The $\Delta$-scaling method has been applied to ultra-relativistic p+p, C+C and Pb+Pb collision data simulated using a high energy Monte Carlo package, LUCIAE 3.0. The $\Delta$-scaling is found to be valid for some physical variables, such as charged particle multiplicity, strange particle multiplicity and number of binary nucleon-nucleon collisions from these simulated nucleus-nucleus collisions over an extended energy ranging from $E_{lab}$ = 20 to 200 A GeV. In addition we derived information entropy from the multiplicity distribution as a function of beam energy for these collisions.Comment: 4 pages, 4 figures, 1 table; to appear in the July Issue of Chin. Phys. Lett.. Web Page: http://www.iop.org/EJ/journal/CP

Statistical nature of cluster emission in nuclear liquid-vapour phase coexistence

The emission of nuclear clusters is investigated within the framework of isospin dependent lattice gas model and classical molecular dynamics model. It is found that the emission of individual cluster which is heavier than proton is almost Poissonian except near the transition temperature at which the system is leaving the liquid-vapor phase coexistence and the thermal scaling is observed by the linear Arrhenius plots which is made from the average multiplicity of each cluster versus the inverse of temperature in the liquid vapor phase coexistence. The slopes of the Arrhenius plots, {\it i.e.} the "emission barriers", are extracted as a function of the mass or charge number and fitted by the formula embodied with the contributions of the surface energy and Coulomb interaction. The good agreements are obtained in comparison with the data for low energy conditional barriers. In addition, the possible influences of the source size, Coulomb interaction and "freeze-out" density and related physical implications are discussed

LSD1 is essential for oocyte meiotic progression by regulating CDC25B expression in mice

Mammalian oocytes are arrested at prophase I until puberty when hormonal signals induce the resumption of meiosis I and progression to meiosis II. Meiotic progression is controlled by CDK1 activity and is accompanied by dynamic epigenetic changes. Although the signalling pathways regulating CDK1 activity are well defined, the functional significance of epigenetic changes remains largely unknown. Here we show that LSD1, a lysine demethylase, regulates histone H3 lysine 4 di-methylation (H3K4me2) in mouse oocytes and is essential for meiotic progression. Conditional deletion of Lsd1 in growing oocytes results in precocious resumption of meiosis and spindle and chromosomal abnormalities. Consequently, most Lsd1-null oocytes fail to complete meiosis I and undergo apoptosis. Mechanistically, upregulation of CDC25B, a phosphatase that activates CDK1, is responsible for precocious meiotic resumption and also contributes to subsequent spindle and chromosomal defects. Our findings uncover a functional link between LSD1 and the major signalling pathway governing meiotic progression