Constraints on the symmetry energy from observational probes of the neutron star crust

A number of observed phenomena associated with individual neutron star systems or neutron star populations find explanations in models in which the neutron star crust plays an important role. We review recent work examining the sensitivity to the slope of the symmetry energy $L$ of such models, and constraints extracted on $L$ from confronting them with observations. We focus on six sets of observations and proposed explanations: (i) The cooling rate of the neutron star in Cassiopeia A, confronting cooling models which include enhanced cooling in the nuclear pasta regions of the inner crust, (ii) the upper limit of the observed periods of young X-ray pulsars, confronting models of magnetic field decay in the crust caused by the high resistivity of the nuclear pasta layer, (iii) glitches from the Vela pulsar, confronting the paradigm that they arise due to a sudden re-coupling of the crustal neutron superfluid to the crustal lattice after a period during which they were decoupled due to vortex pinning, (iv) The frequencies of quasi-periodic oscillations in the X-ray tail of light curves from giant flares from soft gamma-ray repeaters, confronting models of torsional crust oscillations, (v) the upper limit on the frequency to which millisecond pulsars can be spun-up due to accretion from a binary companion, confronting models of the r-mode instability arising above a threshold frequency determined in part by the viscous dissipation timescale at the crust-core boundary, and (vi) the observations of precursor electromagnetic flares a few seconds before short gamma-ray bursts, confronting a model of crust shattering caused by resonant excitation of a crustal oscillation mode by the tidal gravitational field of a companion neutron star just before merger.Comment: 19 pages, 10 figure and 1 tabl

A Field Technique Measuring Virus Decay and Potential Aerosol Hazard from Wastewater Sprinkler Irrigation

The increased use of domestic wastewater for irrigation purposes has stimulated a growing practice of sprinkler irrigating from oxidation ponds and other domestic wastewaters. Aerosols generated from these sprinkler irrigation systems may contain potentially hazardous pathogens. Subsequently, the aerosols can contain infective viruses which can be carried through the air to surrounding populations. Thus, a public health hazard can be created by sprinkler irrigating domestic wastewater. This study is an investigation of a means by which the virus decay rate of viruses in aerosols and the potentials hazard of sprinkler irrigation aerosol clouds may be examined. A means of injection of a human and animal virus stimulant, MS-2 bacteriophage, is described. In addition, the factors which are known to effect the survival of viruses in aerosols are discussed. The ambient air factors that are known to effect virus survival and which are discussed include relative humidity, air temperature, solar radiation, and aerosol age. The suspending fluid factors that are known to effect virus survival and which are discussed include dissolved inorganic salt contact, dissolved organic content, filterable solids and pH. The decay rate of the aerosolized MS-2 was measured with an all-glass impinger (AGI-30) when the wind velocity and distance of the sampler from the sprinkler system, and the initial and final concentrations of aerosolized MS-2 virus were known. The aerosol hazard of a domestic wastewater sprinkler irrigation system is defined in terms of the likelihood of infective aerosol particles to be inhaled and penetrate the human lung. Thus, the aerosol hazard is a function of aerosol particle size. The aerosol particle size distribution of the infective aerosol cloud was measured wit the Andersen sampler. A high and homogeneous concentration of the virus in the wastewater was insured by using pressure differentials in the sprinkler irrigation delivery line. By injecting the MS-2 virus into the line at a constant rate along with a tracer, Bacillus subtilus var niger (Bacillus globigii) spores, the decay rate of the virus during airborne exposure to environmental factors could be determined. The decay rate was determined assuming the environmental factors had no affect on the concentration of the tracer. It was proposed that the environmental engineer, after knowing the virus decay rates under varying environmental conditions, can define buffer zones which would be required around sprinkler irrigation sites. The buffer zone would reduce the possibility of contaminating humans by prohibiting access. The usefulness of the filed technique was demonstrated and the MS-2 was found to undergo a 33.3 percent decay per minute in the dark (no solar radiation) at 33 percent relative humidity, 70.6 percent dissolved organic material, 29.4 percent dissolved inorganic salts, 30.1 mg/1 filterable solids, and 17 degree C air temperature. The aerosol cloud resulting from the spray irrigation process appeared potentially hazardous because the Andersen sampler collected 84.2 percent of the virus infective droplets in the size range that could be inhaled

Conserved Chromosomal Positions of Dual Domains of the ets Protooncogene in Cats, Mice, and Humans

The mammalian protooncogene homologue of the avian v-ets sequence from the E26 retrovirus consists of two sequentially distinct domains located on different chromosomes. Using somatic cell hybrid panels, we have mapped the mammalian homologue of the 5\u27 v-ets-domain to chromosome 11 (ETS1) in man, to chromosome 9 (Ets-1) in mouse, and to chromosome D1 (ETS1) in the domestic cat. The mammalian homologue of the 3\u27 v-ets domain was similarly mapped to human chromosome 21 (ETS2), to mouse chromosome 16 (Ets-2), and to feline chromosome C2 (ETS2). Both protooncogenes fell in syntenic groups of homologous linked loci that were conserved among the three species. The occurrence of two distinct functional protooncogenes and their conservation of linkage positions in the three mammalian orders indicate that these two genes have been separate since before the evolutionary divergence of mammals

Imprints of Nuclear Symmetry Energy on Properties of Neutron Stars

Significant progress has been made in recent years in constraining the density dependence of nuclear symmetry energy using terrestrial nuclear laboratory data. Around and below the nuclear matter saturation density, the experimental constraints start to merge in a relatively narrow region. At supra-saturation densities, there are, however, still large uncertainties. After summarizing the latest experimental constraints on the density dependence of nuclear symmetry energy, we highlight a few recent studies examining imprints of nuclear symmetry energy on the binding energy, energy release during hadron-quark phase transitions as well as the $w$-mode frequency and damping time of gravitational wave emission of neutron stars.Comment: 10 pages. Invited talk given in the Nuclear Astrophysics session of INPC2010, July 4-9, 2010, Vancouver, Canada; Journal of Physics: Conference Series (2011

IFN-γ alters the expression of diverse immunity related genes in a cell culture model designed to represent maturing neutrophils

<div><p>The cytokine interferon-γ (IFN-γ) is approved as a drug to treat chronic granulomatous disease (CGD) and osteopetrosis and is also used in hyperimmunoglobulin E syndromes. Patients with CGD have defects in proteins of the NOX2 NADPH oxidase system. This leads to reduced production of microbicidal ROS by PMNs and recurrent life threatening infections. The goal of this study was to better understand how IFN-γ might support phagocyte function in these diseases, and to obtain information that might expand potential uses for IFN-γ. Neutrophils mature in the bone marrow and then enter the blood where they quickly undergo apoptotic cell death with a half-life of only 5–10 hours. Therefore we reasoned that IFN-γ might exert its effects on neutrophils via prolonged exposure to cells undergoing maturation in the marrow rather than by its brief exposure to short-lived circulating cells. To explore this possibility we made use of PLB-985 cells, a myeloblast-like myeloid cell line that can be differentiated into a mature, neutrophil-like state by treatment with various agents including DMSO. In initial studies we investigated transcription and protein expression in PLB-985 cells undergoing maturation in the presence or absence of IFN-γ. We observed IFN-γ induced differences in expression of genes known to be involved in classical aspects of neutrophil function (transmigration, chemotaxis, phagocytosis, killing and pattern recognition) as well as genes involved in apoptosis and other mechanisms that regulating neutrophil number. We also observed differences for genes involved in the major histocompatibility complex I (MHCI) and MHCII systems whose involvement in neutrophil function is controversial and not well defined. Finally, we observed significant changes in expression of genes encoding guanylate binding proteins (Gbps) that are known to have roles in immunity but which have not as yet been linked to neutrophil function. We propose that changes in the expression within these classes of genes could help explain the immune supportive effects of IFN-γ. Next we explored if the effect of IFN-γ on expression of these genes is dependent on whether the cells are undergoing maturation; to do this we compared the effects of IFN-γ on cells cultured with and without DMSO. For a subset of genes the expression level changes caused by IFN-γ were much greater in maturing cells than non-maturing cells. These findings indicate that developmental changes associated with cell maturation can modulate the effects of IFN-γ but that this is gene specific. Since the effects of IFN-γ depend on whether cells are maturing, the gene expression changes observed in this study must be due to more than just prolonged application of IFN-γ and are instead the result of interplay between cell maturation and changes caused by the chemokine. This supports our hypothesis that the effects of IFN-γ on developing neutrophils in the bone marrow may be very different from its effects on mature cells in the blood. Collectively the findings in this study enhance our understanding of the effects of IFN-γ on maturing myeloid cells and indicate possible mechanisms by which this cytokine could support immune function.</p></div

Innate immune receptors.

<p>Innate immune receptors.</p

Proteins involved or potentially involved in antigen presentation by MHCII and MHCI.

<p>Proteins involved or potentially involved in antigen presentation by MHCII and MHCI.</p

Proteins involved in basic neutrophil functions.

<p>Proteins involved in basic neutrophil functions.</p

Gene dependent differences in expression changes induced by IFN-γ applied to already mature or maturing cells.

<p>Gene dependent differences in expression changes induced by IFN-γ applied to already mature or maturing cells.</p