7,989 research outputs found

    Survey of Occupational Hygiene Professional Practice in Spanish-Speaking Countries

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    Professional credentialing schemes based on experience and examination are used to clarify the scope and required competencies associated with the practice of a profession. National occupational hygiene (OH) credentials developed in 17 nations have been recognized by the International Occupational Hygiene Association (IOHA) to meet or exceed the requirements of a model certification program. To date, there is no credentialing or certification scheme for occupational hygienists in Spanish-speaking regions. To fill this void, a new credentialing body has been created named the Iberoamerican Board of Occupational Hygiene (JIHO). As a first step to the development of a certification exam for a profession, it is necessary to determine the interest in an occupational hygiene certification exam in Spanish and to clarify the most common work practices for those practicing the profession. To determine the proper exam weightings for occupational hygiene competencies needed to practice in Spanish-speaking regions JIHO conducted a comprehensive survey of professional practice of occupational hygiene in nations where Spanish is spoken as the primary language. Surveys were sent to 456 practicing occupational hygienists in nine different countries on a variety of topics. Results indicated that 79% of respondents felt the need for an OH certification exam in Spanish was very or extremely important. The most frequent and important technical competencies utilized in practice were (1) awareness about the health effects of hazardous agents to make decisions about workplace activities and exposures, (2) application of the hierarchy of controls, control banding, hazard communication, training of employees and other methods to reduce worker exposure and workplace risks, and (3) application of principles to recognize and control biohazards in the workplace. The study results have been used to guide the weighting and importance of various technical topics and rubrics on the JIHO exam. Data from this study can be used in the development of certification examinations, to improve international coherence in the profession, and the development of educational programs in OH

    The MASSIVE Survey - VIII. Stellar Velocity Dispersion Profiles and Environmental Dependence of Early-Type Galaxies

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    We measure the radial profiles of the stellar velocity dispersions, σ(R)\sigma(R), for 90 early-type galaxies (ETGs) in the MASSIVE survey, a volume-limited integral-field spectroscopic (IFS) galaxy survey targeting all northern-sky ETGs with absolute KK-band magnitude MK<−25.3M_K < -25.3 mag, or stellar mass M∗>4×1011M⊙M_* > 4 \times 10^{11} M_\odot, within 108 Mpc. Our wide-field 107" ×\times 107" IFS data cover radii as large as 40 kpc, for which we quantify separately the inner (2 kpc) and outer (20 kpc) logarithmic slopes Îłinner\gamma_{\rm inner} and Îłouter\gamma_{\rm outer} of σ(R)\sigma(R). While Îłinner\gamma_{\rm inner} is mostly negative, of the 56 galaxies with sufficient radial coverage to determine Îłouter\gamma_{\rm outer} we find 36% to have rising outer dispersion profiles, 30% to be flat within the uncertainties, and 34% to be falling. The fraction of galaxies with rising outer profiles increases with M∗M_* and in denser galaxy environment, with 10 of the 11 most massive galaxies in our sample having flat or rising dispersion profiles. The strongest environmental correlations are with local density and halo mass, but a weaker correlation with large-scale density also exists. The average Îłouter\gamma_{\rm outer} is similar for brightest group galaxies, satellites, and isolated galaxies in our sample. We find a clear positive correlation between the gradients of the outer dispersion profile and the gradients of the velocity kurtosis h4h_4. Altogether, our kinematic results suggest that the increasing fraction of rising dispersion profiles in the most massive ETGs are caused (at least in part) by variations in the total mass profiles rather than in the velocity anisotropy alone.Comment: Accepted/in press, MNRA

    The Radio Light Curve of the Gamma-Ray Nova in V407 Cyg: Thermal Emission from the Ionized Symbiotic Envelope, Devoured from Within by the Nova Blast

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    We present multi-frequency radio observations of the 2010 nova event in the symbiotic binary V407 Cygni, obtained with the Karl G. Jansky Very Large Array and spanning 1-45 GHz and 17-770 days following discovery. This nova---the first ever detected in gamma rays---shows a radio light curve dominated by the wind of the Mira giant companion, rather than the nova ejecta themselves. The radio luminosity grew as the wind became increasingly ionized by the nova outburst, and faded as the wind was violently heated from within by the nova shock. This study marks the first time that this physical mechanism has been shown to dominate the radio light curve of an astrophysical transient. We do not observe a thermal signature from the nova ejecta or synchrotron emission from the shock, due to the fact that these components were hidden behind the absorbing screen of the Mira wind. We estimate a mass loss rate for the Mira wind of Mdot_w ~ 10^-6 M_sun/yr. We also present the only radio detection of V407 Cyg before the 2010 nova, gleaned from unpublished 1993 archival VLA data, which shows that the radio luminosity of the Mira wind varies by a factor of >~20 even in quiescence. Although V407 Cyg likely hosts a massive accreting white dwarf, making it a candidate progenitor system for a Type Ia supernova, the dense and radially continuous circumbinary material surrounding V407 Cyg is inconsistent with observational constraints on the environments of most Type Ia supernovae.Comment: Resubmitted to ApJ after incorporating referee's comment

    Radio studies of novae: a current status report and highlights of new results

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    Novae, which are the sudden visual brightening triggered by runaway thermonuclear burning on the surface of an accreting white dwarf, are fairly common and bright events. Despite their astronomical significance as nearby laboratories for the study of nuclear burning and accretion phenomena, many aspects of these common stellar explosions are observationally not well-constrained and remain poorly understood. Radio observations, modeling and interpretation can potentially play a crucial role in addressing some of these puzzling issues. In this review on radio studies of novae, we focus on the possibility of testing and improving the nova models with radio observations, and present a current status report on the progress in both the observational front and theoretical developments. We specifically address the issues of accurate estimation of ejecta mass, multi-phase and complex ejection phenomena, and the effect of a dense environment around novae. With highlights of new observational results, we illustrate how radio observations can shed light on some of these long-standing puzzles.Comment: 19 pages, 4 figures. Review article published in the Bulletin of the Astronomical Society of India (BASI) special issue on nova

    The MASSIVE Survey - VII. The Relationship of Angular Momentum, Stellar Mass and Environment of Early-Type Galaxies

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    We analyse the environmental properties of 370 local early-type galaxies (ETGs) in the MASSIVE and ATLAS3D surveys, two complementary volume-limited integral-field spectroscopic (IFS) galaxy surveys spanning absolute KK-band magnitude −21.5>MK>−26.6-21.5 > M_K > -26.6, or stellar mass 8×109<M∗<2×1012M⊙8 \times 10^{9} < M_* < 2 \times 10^{12} M_\odot. We find these galaxies to reside in a diverse range of environments measured by four methods: group membership (whether a galaxy is a brightest group/cluster galaxy, satellite, or isolated), halo mass, large-scale mass density (measured over a few Mpc), and local mass density (measured within the NNth neighbour). The spatially resolved IFS stellar kinematics provide robust measurements of the spin parameter λe\lambda_e and enable us to examine the relationship among λe\lambda_e, M∗M_*, and galaxy environment. We find a strong correlation between λe\lambda_e and M∗M_*, where the average λe\lambda_e decreases from ∌0.4\sim 0.4 to below 0.1 with increasing mass, and the fraction of slow rotators fslowf_{\rm slow} increases from ∌10\sim 10% to 90%. We show for the first time that at fixed M∗M_*, there are almost no trends between galaxy spin and environment; the apparent kinematic morphology-density relation for ETGs is therefore primarily driven by M∗M_* and is accounted for by the joint correlations between M∗M_* and spin, and between M∗M_* and environment. A possible exception is that the increased fslowf_{\rm slow} at high local density is slightly more than expected based only on these joint correlations. Our results suggest that the physical processes responsible for building up the present-day stellar masses of massive galaxies are also very efficient at reducing their spin, in any environment.Comment: Accepted to MNRA

    Cloning and Sequencing of Protein Kinase cDNA from Harbor Seal (Phoca vitulina) Lymphocytes

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    Protein kinases (PKs) play critical roles in signal transduction and activation of lymphocytes. The identification of PK genes provides a tool for understanding mechanisms of immunotoxic xenobiotics. As part of a larger study investigating persistent organic pollutants in the harbor seal and their possible immunomodulatory actions, we sequenced harbor seal cDNA fragments encoding PKs. The procedure, using degenerate primers based on conserved motifs of human protein tyrosine kinases (PTKs), successfully amplified nine phocid PK gene fragments with high homology to human and rodent orthologs. We identified eight PTKs and one dual (serine/threonine and tyrosine) kinase. Among these were several PKs important in early signaling events through the B- and T-cell receptors (FYN, LYN, ITK and SYK) and a MAP kinase involved in downstream signal transduction. V-FGR, RET and DDR2 were also expressed. Sequential activation of protein kinases ultimately induces gene transcription leading to the proliferation and differentiation of lymphocytes critical to adaptive immunity. PKs are potential targets of bioactive xenobiotics, including persistent organic pollutants of the marine environment; characterization of these molecules in the harbor seal provides a foundation for further research illuminating mechanisms of action of contaminants speculated to contribute to large-scale die-offs of marine mammals via immunosuppression
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