2,601 research outputs found

    Cosmic Ray Rejection by Linear Filtering of Single Images

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    We present a convolution-based algorithm for finding cosmic rays in single well-sampled astronomical images. The spatial filter used is the point spread function (approximated by a Gaussian) minus a scaled delta function, and cosmic rays are identified by thresholding the filtered image. This filter searches for features with significant power at spatial frequencies too high for legitimate objects. Noise properties of the filtered image are readily calculated, which allows us to compute the probability of rejecting a pixel not contaminated by a cosmic ray (the false alarm probability). We demonstrate that the false alarm probability for a pixel containing object flux will never exceed the corresponding probability for a blank sky pixel, provided we choose the convolution kernel appropriately. This allows confident rejection of cosmic rays superposed on real objects. Identification of multiple-pixel cosmic ray hits can be enhanced by running the algorithm iteratively, replacing flagged pixels with the background level at each iteration.Comment: Accepted for publication in PASP (May 2000 issue). An iraf script implementing the algorithm is available from the author, or from http://sol.stsci.edu/~rhoads/ . 16 pages including 3 figures. Uses AASTeX aaspp4 styl

    The Perceived Effectiveness of Christian and Secular Graduate Training Programs in Preparing Christian Psychologists to Deal With Experiences of Sexual Attraction

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    Most psychologists experience feelings of sexual attraction toward clients, and for some Christian therapists this situation can be further complicated by their tendency to deny such sexual attraction. How effective are graduate training programs in teaching Christian psychologists to manage feelings of sexual attraction in professional contexts? In this survey, 258 Christian psychologists answered questions regarding their graduate training. A positive training environment was related to healthy coping responses in managing feelings of sexual attraction, and graduates of explicitly Christian training programs reported greater satisfaction with training conditions than graduates of secular programs. Those involved in training professional psychologists should consider the general training environment in addition to specific course work about managing feelings of sexual attraction

    The Dynamics and Light Curves of Beamed Gamma Ray Burst Afterglows

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    The energy requirements of gamma ray bursts have in past been poorly constrained because of three major uncertainties: The distances to bursts, the degree of burst beaming, and the efficiency of gamma ray production. The first of these has been resolved, with both indirect evidence (the distribution of bursts in flux and position) and direct evidence (redshifted absorption features in the afterglow spectrum of GRB 970508) pointing to cosmological distances. We now wish to address the second uncertainty. Afterglows allow a statistical test of beaming, described in an earlier paper. In this paper, we modify a standard fireball afterglow model to explore the effects of beaming on burst remnant dynamics and afterglow emission. If the burst ejecta are beamed into angle zeta, the burst remnant's evolution changes qualitatively once its bulk Lorentz factor Gamma < 1/zeta: Before this, Gamma declines as a power law of radius, while afterwards, it declines exponentially. This change results in a broken power law light curve whose late-time decay is faster than expected for a purely spherical geometry. These predictions disagree with afterglow observations of GRB 970508. We explored several variations on our model, but none seems able to change this result. We therefore suggest that this burst is unlikely to have been highly beamed, and that its energy requirements were near those of isotropic models. More recent afterglows may offer the first practical applications for our beamed models.Comment: 18 pages, uses emulateapj.sty, four embedded postscript figures. Submitted to The Astrophysical Journal, 199

    Questioning the Slippery Slope : Ethical Beliefs and Behaviors of Private Office-Based and Church-Based Therapists

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    Counselors and other mental health professionals whose primary office is in a church building often face unique challenges in maintaining appropriate client-therapist boundaries. A sample of 497 Christian counselors responded to an 88-item survey of their ethical beliefs and behaviors. Of the respondents, 148 reported a church as their primary work setting and 162 reported a private office as their primary work setting. Survey results were factor analyzed, then church-based therapists were compared with private office-based therapists regarding their views of ethical behaviors. Although church-based therapists take greater liberties with multiple-role relationships than private office-based therapists, they appear similar with regard to other ethical beliefs and behaviors. Results suggest that churchbased therapists who take liberties in nonsexual multiple-role relationships are no more likely than other therapists to violate other ethical standards

    The Near Infrared and Multiwavelength Afterglow of GRB 000301c

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    We present near-infrared observations of the counterpart of GRB 000301c. The K' filter (2.1 micron) light curve shows a well-sampled break in the decay slope at t=3.5 days post-burst. The early time slope is very shallow (~ -0.1), while the late time slope is steep (-2.2). Comparison with the optical (R band) light curve shows marginally significant differences, especially in the early time decay slope (which is steeper in the optical) and the break time (which occurs later in the optical). This is contrary to the general expectation that light curve breaks should either be achromatic (e.g., for breaks due to collimation effects) or should occur later at longer wavelengths (for most other breaks). The observed color variations might be intrinsic to the afterglow, or might indicate systematic errors of > 0.08 magnitude in all fluxes. Even if the break is achromatic, we argue that its sharpness poses difficulties for explanations that depend on collimated ejecta. The R light curve shows further signs of fairly rapid variability (a bump, steep drop, and plateau) that are not apparent in the K' light curve. In addition, by combining the IR-optical-UV data with millimeter and radio fluxes, we are able to constrain the locations of the self-absorption break and cooling break and to infer the location of the spectral peak at t=3 days: f_nu = 3.4 mJy at nu=1e12 Hz. Using the multiwavelength spectral energy distribution, we are able to constrain the blast wave energy, which was E > 3e53 erg if the explosion was isotropic. This implies a maximum gamma ray production efficiency of ~ 0.15 for GRB 000301C.Comment: Accepted to The Astrophysical Journal. 24 pages, 4 figures, 3 tables; uses AASTeX 5 macros. This version includes a new figure (R-K' color vs. time), a better sampled R band light curve, and more extensive discussion of the optical data and error analysi

    Initiating an Entrepreneurial Mindset in the Department of Defense (DoD): Testing a Comprehensive Model

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    Transformation will become vital as senior military leaders prepare to fight tomorrow\u27s battles. The pervasiveness of the entrepreneurial mind set within Department of Defense (DoD) organizations and the ability of senior leaders to foster that mind set will be vital. This research effort tested an integrated model of the entrepreneurial mind set and produced a framework that senior leaders can implement to ignite their organizations\u27 innovative potential and ability to transform. The research used a questionnaire to gather data regarding three entrepreneurial mind set antecedents -- individual characteristics, process, and context -- to determine the level of influence each has on three entrepreneurial outcomes: job performance, job satisfaction, and affective commitment. The questionnaire was administered to an anonymous sample of DoD military and civilian personnel from three Air Force organizations. Results showed that the entrepreneurial mind set was mildly present in DoD, and that all three antecedents together are positively correlated to the entrepreneurial mind set and its outcomes. Further, it showed that process, which is arguably the easiest antecedent for a leader to influence, had the greatest positive impact on the entrepreneurial mind set and its outcomes

    Forgiveness Motives Among Evangelical Christians: Implications for Christian Marriage and Family Therapists

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    Therapists and researchers interested in forgiveness can learn from those who have experienced interpersonal wounds and have chosen to forgive. We interviewed 20 evangelical Christian forgivers, asking about motives for forgiveness. Transcripts were analyzed using qualitative methods. Five categories of motivation are presented: comfort, duty, relational, humility/empathy, and Christian beliefs. Respondents described multiple motives for forgiveness, often combining a desire for comfort or a sense of duty with their Christian beliefs. Four implications for Christian marriage and family therapists are discussed: Expect diversity, avoid moralistic views of motives, remember religious resources in the forgiveness process, and expect benefits, but not immediately

    Forgiveness: More than a Therapeutic Technique

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    Although the concept of forgiveness is accepted by many as profitable in promoting personal and relational healing, some have abandoned its historical connection with religious faith. This uncoupling of religion and forgiveness overlooks a progression of healing that both includes and transcends personal healing for the forgiver, and may rob forgiveness of its therapeutic power. A brief discussion of the historical roots of forgiveness is followed by a proposed model of forgiveness that exemplifies the progression of healing proffered by religious faith. Current trends in the forgiveness literature are considered along with their therapeutic implications

    Ethics Among Christian Counselors: A Survey of Beliefs and Behaviors

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    Previous researchers have reported survey results of the beliefs and behaviors of psychologists (Pope, Tabachnick, & Keith-Spiegel, 1987) and counselors (Gibson & Pope, 1993) with regard to professional ethics. We sent the same instrument to 900 Christian counselors, and received back 496 completed surveys. Rarely and commonly practiced ethical behaviors are described, and differences by sex, age, highest degree, and licensure status are discussed. Although Christian counselors generally appear to have high regard for and good awareness of ethical standards, many unlicensed Christian counselors may benefit from additional training in preventing exploitative counseling relationships. Current professional standards for multiple-role relationships may not apply well to all Christian counseling situations, making an ethics code for Christian counselors an important goal for the immediate future. Implications for training para-professionals and for subsequent research are considered

    GRB Energetics and the GRB Hubble Diagram: Promises and Limitations

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    We present a complete sample of 29 GRBs for which it has been possible to determine temporal breaks (or limits) from their afterglow light curves. We interpret these breaks within the framework of the uniform conical jet model, incorporating realistic estimates of the ambient density and propagating error estimates on the measured quantities. In agreement with our previous analysis of a smaller sample, the derived jet opening angles of those 16 bursts with redshifts result in a narrow clustering of geometrically-corrected gamma-ray energies about E_gamma = 1.33e51 erg; the burst-to-burst variance about this value is a factor of 2.2. Despite this rather small scatter, we demonstrate in a series of GRB Hubble diagrams, that the current sample cannot place meaningful constraints upon the fundamental parameters of the Universe. Indeed for GRBs to ever be useful in cosmographic measurements we argue the necessity of two directions. First, GRB Hubble diagrams should be based upon fundamental physical quantities such as energy, rather than empirically-derived and physically ill-understood distance indicators. Second, a more homogeneous set should be constructed by culling sub-classes from the larger sample. These sub-classes, though now first recognizable by deviant energies, ultimately must be identifiable by properties other than those directly related to energy. We identify a new sub-class of GRBs (``f-GRBs'') which appear both underluminous by factors of at least 10 and exhibit a rapid fading at early times. About 10-20% of observed long-duration bursts appear to be f-GRBs.Comment: Accepted to the Astrophysical Journal (20 May 2003). 19 pages, 3 Postscript figure
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