Dust in the Ionized Medium of the Galaxy: GHRS Measurements of Al III and S III

We present interstellar absorption line measurements of the ions S III and Al III towards six stars using archival Goddard High Resolution Spectrograph data. The ions Al III and S III trace heavily depleted and non-depleted elements, respectively, in ionized gas. We use the photoionization code CLOUDY to derive the ionization correction relating N(Al III)/N(S III) to the gas-phase abundance [Al/S]_i in the ionized gas. For spectral types considered here, the corrections are small and independent of the assumed ionization parameter. Using the results of these photoionization models, we find [Al/S]_i = -1.0 in the ionized gas towards three disk stars. These values of [Al/S]_i (=[Al/H]_i) imply that Al-bearing grains are present in the ionized nebulae around these stars. If the WIM of the Galaxy is photoionized by OB stars, our data for two halo stars imply [Al/S]_i = -0.4 to -0.5 in the WIM and thus the presence of dust grains containing Al in this important phase of the ISM. While photoionization appears to be the most likely origin of the ionization for Al III and S III, we cannot rule out confusion from the presence of hot, collisionally ionized gas along two sightlines. We find that [Al/S]_i in the ionized gas along the six sightlines is anti-correlated with the electron density and average sightline neutral density. The degree of grain destruction in the ionized medium of the Galaxy is not much higher than in the warm neutral medium. The existence of grains in the ionized regions studied here has important implications for the thermal balance of these regions. (Abstract Abridged)Comment: 30 pages including 8 embedded tables and 8 embedded figures. Accepted for publication in the Astrophysical Journa

Pure-radiation gravitational fields with a simple twist and a Killing vector

Pure-radiation solutions are found, exploiting the analogy with the Euler- Darboux equation for aligned colliding plane waves and the Euler-Tricomi equation in hydrodynamics of two-dimensional flow. They do not depend on one of the spacelike coordinates and comprise the Hauser solution as a special subcase.Comment: revtex, 9 page

Regulation of mammalian horizontal gene transfer by apoptotic DNA fragmentation

Previously it was shown that horizontal DNA transfer between mammalian cells can occur through the uptake of apoptotic bodies, where genes from the apoptotic cells were transferred to neighbouring cells phagocytosing the apoptotic bodies. The regulation of this process is poorly understood. It was shown that the ability of cells as recipient of horizontally transferred DNA was enhanced by deficiency of p53 or p21. However, little is known with regard to the regulation of DNA from donor apoptotic cells. Here we report that the DNA fragmentation factor/caspase-activated DNase (DFF/CAD), which is the endonuclease responsible for DNA fragmentation during apoptosis, plays a significant role in regulation of horizontal DNA transfer. Cells with inhibited DFF/CAD function are poor donors for horizontal gene transfer (HGT) while their ability of being recipients of HGT is not affected

Low-threshold analysis of CDMS shallow-site data

Data taken during the final shallow-site run of the first tower of the Cryogenic Dark Matter Search (CDMS II) detectors have been reanalyzed with improved sensitivity to small energy depositions. Four ~224 g germanium and two ~105 g silicon detectors were operated at the Stanford Underground Facility (SUF) between December 2001 and June 2002, yielding 118 live days of raw exposure. Three of the germanium and both silicon detectors were analyzed with a new low-threshold technique, making it possible to lower the germanium and silicon analysis thresholds down to the actual trigger thresholds of ~1 keV and ~2 keV, respectively. Limits on the spin-independent cross section for weakly interacting massive particles (WIMPs) to elastically scatter from nuclei based on these data exclude interesting parameter space for WIMPs with masses below 9 GeV/c^2. Under standard halo assumptions, these data partially exclude parameter space favored by interpretations of the DAMA/LIBRA and CoGeNT experiments' data as WIMP signals, and exclude new parameter space for WIMP masses between 3 GeV/c^2 and 4 GeV/c^2.Comment: 18 pages, 12 figures, 5 table

Exclusion Limits on the WIMP-Nucleon Cross-Section from the First Run of the Cryogenic Dark Matter Search in the Soudan Underground Lab

The Cryogenic Dark Matter Search (CDMS-II) employs low-temperature Ge and Si detectors to seek Weakly Interacting Massive Particles (WIMPs) via their elastic scattering interactions with nuclei. Simultaneous measurements of both ionization and phonon energy provide discrimination against interactions of background particles. For recoil energies above 10 keV, events due to background photons are rejected with >99.99% efficiency. Electromagnetic events very near the detector surface can mimic nuclear recoils because of reduced charge collection, but these surface events are rejected with >96% efficiency by using additional information from the phonon pulse shape. Efficient use of active and passive shielding, combined with the the 2090 m.w.e. overburden at the experimental site in the Soudan mine, makes the background from neutrons negligible for this first exposure. All cuts are determined in a blind manner from in situ calibrations with external radioactive sources without any prior knowledge of the event distribution in the signal region. Resulting efficiencies are known to ~10%. A single event with a recoil of 64 keV passes all of the cuts and is consistent with the expected misidentification rate of surface-electron recoils. Under the assumptions for a standard dark matter halo, these data exclude previously unexplored parameter space for both spin-independent and spin-dependent WIMP-nucleon elastic scattering. The resulting limit on the spin-independent WIMP-nucleon elastic-scattering cross-section has a minimum of 4x10^-43 cm^2 at a WIMP mass of 60 GeV/c^2. The minimum of the limit for the spin-dependent WIMP-neutron elastic-scattering cross-section is 2x10^-37 cm^2 at a WIMP mass of 50 GeV/c^2.Comment: 37 pages, 42 figure

A Search for WIMPs with the First Five-Tower Data from CDMS

We report first results from the Cryogenic Dark Matter Search (CDMS II) experiment running with its full complement of 30 cryogenic particle detectors at the Soudan Underground Laboratory. This report is based on the analysis of data acquired between October 2006 and July 2007 from 15 Ge detectors (3.75 kg), giving an effective exposure of 121.3 kg-d (averaged over recoil energies 10--100 keV, weighted for a weakly interacting massive particle (WIMP) mass of 60 \gev). A blind analysis, incorporating improved techniques for event reconstruction and data quality monitoring, resulted in zero observed events. This analysis sets an upper limit on the WIMP-nucleon spin-independent cross section of 6.6$\times10^{-44}$ cm$^2$ (4.6$\times10^{-44}$ cm$^2$ when combined with previous CDMS Soudan data) at the 90% confidence level for a WIMP mass of 60 \gev. By providing the best sensitivity for dark matter WIMPs with masses above 42 GeV/c$^2$, this work significantly restricts the parameter space for some of the favored supersymmetric models.Comment: 5 pages, 4 figures, submitted to PRL 28 March 200

S-IgA cholera toxin and rotavirus antibody in human colostrum

artículo (arbitrado) -- Universidad de Costa Rica. Instituto de Investigaciones en Salud (INISA), 1979S-IgA cholera toxin and rotavirus antibody inhuman colostrum. Acta Paediatr Scand, 68: 161, 1979.—S-1gA antibodies against cholera toxin and rotavirus were assayed in 43 colostral samples by means of an enzyme-linked immunosorbent assay (ELISA). Ali specimens contained specific S-1gA antibodies against both antigens. Significant antibody titres to the antigens were demonstrated In almost all colostral samples.Universidad de Costa RicaUCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias de la Salud::Instituto de Investigaciones en Salud (INISA

Analysis of the low-energy electron-recoil spectrum of the CDMS experiment

We report on the analysis of the low-energy electron-recoil spectrum from the CDMS II experiment using data with an exposure of 443.2 kg-days. The analysis provides details on the observed counting rate and possible background sources in the energy range of 2 - 8.5 keV. We find no significant excess in the counting rate above background, and compare this observation to the recent DAMA results. In the framework of a conversion of a dark matter particle into electromagnetic energy, our 90% confidence level upper limit of 0.246 events/kg/day at 3.15 keV is lower than the total rate above background observed by DAMA by 8.9$\sigma$. In absence of any specific particle physics model to provide the scaling in cross section between NaI and Ge, we assume a Z^2 scaling. With this assumption the observed rate in DAMA differs from the upper limit in CDMS by 6.8$\sigma$. Under the conservative assumption that the modulation amplitude is 6% of the total rate we obtain upper limits on the modulation amplitude a factor of ~2 less than observed by DAMA, constraining some possible interpretations of this modulation.Comment: 4 pages, 3 figure