470 research outputs found

    Work Attribute Importance and Loyalty Intention: Millennial Generation Psychological Contract

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    This study investigated the importance that junior and senior job-seeking undergraduates (Millennial generation members) place on transactional and relational work attributes; how ratings vary by gender, experiences with layoff, and intended loyalty; and how well ratings match with actual attributes offered by organizations. Results are discussed in context of psychological contract theory. Students (n = 199) and recent graduates working full-time (n = 180) took separate online survey. Students indicated the importance of various work attributes (Ng, Schweitzer, & Lyons, 2010), loyalty intentions, and other related questions. Graduates answered only work attribute questions related to their current employer. Work attributes were factored into new transactional (IMP-T; µ = .78) and relational scales (IMP-R; µ = .91). Key results indicated that students rated relational work attributes more highly than transactional attributes (p \u3c .001); gender had no effect on importance ratings or intended loyalty; and students’ importance ratings were above the workplace reality

    Study of porous wall low density wind tunnel diffusers

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    Porous wall wind tunnel diffusers used with low density hypersonic nozzl

    Magnetic Confinement, Magnetohydrodynamic Waves and Smooth Line Profiles in Active Galactic Nuclei

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    In this paper, we show that if the broad-line region clouds are in approximate energy equipartition between the magnetic field and gravity, as hypothesized by Rees, there will be a significant effect on the shape and smoothness of broad emission-line profiles in active galactic nuclei. Linewidths of contributing clouds or flow elements are much wider than their thermal widths, because of the presence of non-dissipative magnetohydrodynamic waves and their collective contribution produce emission-line profiles broader and smoother than would be expected if a magnetic field were not present. As an illustration, a simple model of isotropically emitting clouds, normally distributed in velocity, is used to show that smoothness can be achieved for less than ∼8×104 clouds and may even be as low as a few hundred. We conclude that magnetic confinement has far-reaching consequences for observing and modelling active galactic nuclei

    Magnetic Confinement, MHD Waves, and Smooth Line Profiles in AGN

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    In this paper, we show that if the broad line region clouds are in approximate energy equipartition between the magnetic field and gravity, as hypothesized by Rees, there will be a significant effect on the shape and smoothness of broad emission line profiles in active galactic nuclei. Line widths of contributing clouds or flow elements are much wider than their thermal widths, due to the presence of non-dissipative MHD waves, and their collective contribution produce emission line profiles broader and smoother than would be expected if a magnetic field were not present. As an illustration, a simple model of isotropically emitting clouds, normally distributed in velocity, is used to show that smoothness can be achieved for less than 80,000 clouds and may even be as low as a few hundred. We conclude that magnetic confinement has far reaching consequences for observing and modeling active galactic nuclei.Comment: to appear in MNRA

    On the Effects of Dissipative Turbulence on the Narrow Emission-Line Ratios in Seyfert Galaxies

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    We present a photoionization model study of the effects of micro-turbulence and dissipative heating on emission lines for number and column densities, elemental abundances, and ionizations typical for the narrow emission line regions (NLRs) of Seyfert galaxies. Earlier studies of NLR spectra generally found good agreement between the observations and the model predictions for most strong emission lines, such as [O III] λ\lambda5007, [O II] λ\lambda3727, [N II] λ\lambda6583, [Ne III] λ\lambda3869, and the H and He recombination lines. Nevertheless, the strengths of lines from species with ionization potentials greater than that of He+^{+}(54.4 eV), e.g. N+4^{+4} and Ne+4^{+4}, were often under-predicted. Among the explanations suggested for these discrepancies were (selectively) enhanced elemental abundances and contributions from shock heated gas. Interestingly, the NLR lines have widths of several 100 km s1^{-1}, well in excess of the thermal broadening. If this is due to micro-turbulence, and the turbulence dissipates within the emission-line gas, the gas can be heated in excess of that due to photoionization. We show that the combined effects of turbulence and dissipative heating can strongly enhance N V λ\lambda1240 (relative to He II λ\lambda1640), while the heating alone can boost the strength of [Ne V] λ\lambda3426. We suggest that this effect is present in the NLR, particularly within \sim 100 pc of the central engine. Finally, since micro-turbulence would make clouds robust against instabilities generated during acceleration, it is not likely to be a coincidence that the radially outflowing emission-line gas is turbulent.Comment: 29 oages, including 10 figures. Accepted for publication in the Astrophysical Journa

    H-beta Line Width and the UV-X-ray Spectra of Luminous AGN

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    The width of the broad H-beta emission line is the primary defining characteristic of the NLS1 class. This parameter is also an important component of Boroson and Green's optical Eigenvector 1 (EV1), which links steeper soft X-ray spectra with narrower H-beta emission, stronger H-beta blue wing, stronger optical Fe II emission, and weaker [O III] lambda 5007. Potentially, EV1 represents a fundamental physical process linking the dynamics of fueling and outflow with the accretion rate. We attempted to understand these relationships by extending the optical spectra into the UV for a sample of 22 QSOs with high quality soft-X-ray spectra, and discovered a whole new set of UV relationships that suggest that high accretion rates are linked to dense gas and perhaps nuclear starbursts. While it has been argued that narrow (BLR) H-beta means low Black Hole mass in luminous NLS1s, the C IV, lambda 1549 and Ly alpha emission lines are broader, perhaps the result of outflows driven by their high Eddington accretion rates. We present some new trends of optical-UV with X-ray spectral energy distributions. Steeper X-ray spectra appear associated with stronger UV relative to optical continua, but the presence of strong UV absorption lines is associated with depressed soft X-rays and redder optical-UV continua.Comment: Invited talk presented at the Joint MPE,AIP,ESO workshop on NLS1s, Bad Honnef, Dec. 1999, to appear in New Astronomy Reviews; also available at http://wave.xray.mpe.mpg.de/conferences/nls1-worksho

    Complex X-ray Absorption and the Fe Kalpha Profile in NGC 3516

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    We present data from simultaneous Chandra, XMM-Newton and BeppoSAX observations of the Seyfert 1 galaxy NGC 3516, taken during 2001 April and Nov. We have investigated the nature of the very flat observed X-ray spectrum. Chandra grating data show the presence of X-ray absorption lines, revealing two distinct components of the absorbing gas, one which is consistent with our previous model of the UV/X-ray absorber while the other, which is outflowing at a velocity of ~1100 km/s has a larger column density and is much more highly ionized. The broad-band spectral characteristics of the X-ray continuum observed with XMM during 2001 April, reveal the presence of a third layer of absorption consisting of a very large column (~2.5 x 10E23 cm^-2) of highly ionized gas with a covering fraction ~50%. This low covering fraction suggests that the absorber lies within a few lt-days of the X-ray source and/or is filamentary in structure. Interestingly, these absorbers are not in thermal equilibrium with one another. The two new components are too highly ionized to be radiatively accelerated, which we suggest is evidence for a hydromagnetic origin for the outflow. Applying our model to the Nov dataset, we can account for the spectral variability primarily by a drop in the ionization states of the absorbers, as expected by the change in the continuum flux. When this complex absorption is accounted for we find the underlying continuum to be typical of Seyfert 1 galaxies. The spectral curvature attributed to the high column absorber, in turn, reduces estimates of the flux and extent of any broad Fe emission line from the accretion disk.Comment: 33 pages, 9 figures, accepted for publication in Ap

    Assessing the feasibility, acceptability and potential effectiveness of an integrated approach to smoking cessation for new and expectant fathers: The Dads in Gear study protocol.

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    BACKGROUND: Evidence related to the effects of tobacco exposure in pregnancy and on infant and child health have focused on women's smoking cessation. Less often addressed is men's smoking, which when continued in fatherhood, reduces the chances of female partners' cessation and can negatively impact children's health as well as men's health. Dads in Gear (DIG) is an innovative program designed specifically for new fathers who want to reduce and quit smoking that includes three components: smoking cessation, fathering, and physical activity. The over-arching purpose of this study is to evaluate the feasibility of the DIG program and provide estimates of program efficacy. The purpose of this article is to describe the rationale and protocol for evaluating the DIG program's feasibility, acceptability and potential effectiveness. METHODS: Using a prospective, non-comparative design, the DIG program will be implemented and evaluated in six communities. The program will be offered by trained facilitators to fathers who currently smoke and want to quit. The RE-AIM framework will guide the evaluation. Open-ended questions in participant surveys, and semi-structured interviews and weekly telephone de-briefs with facilitators will provide data for a process evaluation. Estimates of effectiveness include smoking behavior, fathering and physical activity measures at baseline, end of program, and 3-month follow up. CONCLUSION: The DIG program could support positive changes with respect to smoking cessation, physical activity and overall health for men. These effects could also promote family health. The program might also provide an effective model for engaging men in other health behavior change
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