391 research outputs found

    Quasar Black Hole Masses from Velocity Dispersions

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    Much progress has been made in measuring black hole (BH) masses in (non-active) galactic nuclei using the tight correlation between stellar velocity dispersions (sigma) in galaxies and the mass of their central BH. The use of this correlation in quasars, however, is hampered by the difficulty in measuring sigma in host galaxies that tend to be overpowered by their bright nuclei. We discuss results from a project that focuses on z~0.3 quasars suffering from heavy extinction at shorter wavelengths. This makes it possible to obtain clean spectra of the hosts in the spectral regions of interest, while broad lines (like H-alpha) are still visible at longer wavelengths. We compare BH masses obtained from velocity dispersions to those obtained from the broad line region and thus probe the evolution of this relation and BH growth with redshift and luminosity. Our preliminary results show an offset between the position of our objects and the local relation, in the sense that red quasars have, on average, lower velocity dispersions than local galaxies. We discuss possible biases and systematic errors that may affect our results.Comment: 4 pages, to appear in the proceedings of the 2nd Kolkata conference on Observational Evidence for Black Holes in the Universe, ed. S. Chakrabarti (AIP

    Acculturation, coping, and integration success of international skilled migrants: An integrative review and multilevel framework

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    In this article, we review the limited but growing body of research on international skilled migrants and examine to what extent knowledge generated in adjacent research streams-specifically, work on assigned and self-initiated expatriates-can be meaningfully applied to aid our under- standing of the challenges, coping strategies, and acculturation dynamics of skilled migrants. We develop a framework that explains how variables and processes at multiple levels (individual, organisational, and societal) influence migrant acculturation and coping and result in integration-related outcomes in the domains of personal/family life and workplace/career. We discuss directions for future research and implications for practice

    Dynamic multilateral markets

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    We study dynamic multilateral markets, in which players' payoffs result from intra-coalitional bargaining. The latter is modeled as the ultimatum game with exogenous (time-invariant) recognition probabilities and unanimity acceptance rule. Players in agreeing coalitions leave the market and are replaced by their replicas, which keeps the pool of market participants constant over time. In this infinite game, we establish payoff uniqueness of stationary equilibria and the emergence of endogenous cooperation structures when traders experience some degree of (heterogeneous) bargaining frictions. When we focus on market games with different player types, we derive, under mild conditions, an explicit formula for each type's equilibrium payoff as the market frictions vanish

    Hybrid modeling of collaborative freight transportation planning using agent-based simulation, auction-based mechanisms, and optimization

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    This is the author accepted manuscript. The final version is available from SAGE Publications via the DOI in this recordThe sharing economy is a peer-to-peer economic model characterized by people and organizations sharing resources. With the emergence of such economies, an increasing number of logistics providers seek to collaborate and derive benefit from the resultant economic efficiencies, sustainable operations, and network resilience. This study investigates the potential for collaborative planning enabled through a Physical Internet-enabled logistics system in an urban area that acts as a freight transport hub with several e-commerce warehouses. Our collaborative freight transportation planning approach is realized through a three-layer structured hybrid model that includes agent-based simulation, auction mechanism, and optimization. A multi-agent model simulates a complex transportation network, an auction mechanism facilitates allocating transport services to freight requests, and a simulation–optimization technique is used to analyze strategic transportation planning under different objectives. Furthermore, sensitivity analyses and Pareto efficiency experiments are conducted to draw insights regarding the effect of parameter settings and multi-objectives. The computational results demonstrate the efficacy of our developed model and solution approach, tested on a real urban freight transportation network in a major US city

    Business cooperation technology between a swimming coach-instructor and parents of infants

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    The experimental program for the development of swimming skills in infants with the help of our proposed online pedagogical technology of cooperation between an instructor and parents to improve their health-improving competencies has shown greater efficiency compared to the traditional program. And it can be recommended for use in health-improving swimming centers for infants and in children’s clinic

    The Lick AGN Monitoring Project 2011: Spectroscopic Campaign and Emission-Line Light Curves

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    In the Spring of 2011 we carried out a 2.5 month reverberation mapping campaign using the 3 m Shane telescope at Lick Observatory, monitoring 15 low-redshift Seyfert 1 galaxies. This paper describes the observations, reductions and measurements, and data products from the spectroscopic campaign. The reduced spectra were fitted with a multicomponent model in order to isolate the contributions of various continuum and emission-line components. We present light curves of broad emission lines and the AGN continuum, and measurements of the broad H-beta line widths in mean and root-mean square (rms) spectra. For the most highly variable AGNs we also measured broad H-beta line widths and velocity centroids from the nightly spectra. In four AGNs exhibiting the highest variability amplitudes, we detect anticorrelations between broad H-beta width and luminosity, demonstrating that the broad-line region "breathes" on short timescales of days to weeks in response to continuum variations. We also find that broad H-beta velocity centroids can undergo substantial changes in response to continuum variations; in NGC 4593 the broad H-beta velocity shifted by ~250 km/s over a one-month duration. This reverberation-induced velocity shift effect is likely to contribute a significant source of confusion noise to binary black hole searches that use multi-epoch quasar spectroscopy to detect binary orbital motion. We also present results from simulations that examine biases that can occur in measurement of broad-line widths from rms spectra due to the contributions of continuum variations and photon-counting noise.Comment: 33 pages, 28 figures, accepted for publication in ApJ Supplement Serie

    Clinicians' perspectives on supporting individuals with severe anorexia nervosa in specialist eating disorder intensive treatment settings

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    BACKGROUND: Admissions to intensive treatment (i.e., inpatient [IP] and/or day patient [DP]) for individuals with severe anorexia nervosa (AN) are common. Growing literature indicates potential risks and benefits of each intensive treatment approach; however, existing research has focused on patient and carer perspectives of these treatments. Also, there is scant empirical evidence available for guiding the parameters of intensive treatments for AN. We therefore explored clinicians' perspectives and experience of supporting adults with severe AN in intensive settings. METHODS: We conducted twenty one semi-structured interviews with clinicians who deliver intensive treatments (i.e., IP and/or DP) for individuals with severe AN across four specialist Eating Disorder Services in the United Kingdom between May 2020 and June 2021. We asked clinicians about their views and experiences of supporting individuals with severe AN in intensive treatment settings and the challenges and opportunities associated with IP and DP treatment. Data were analysed using reflexive thematic analysis supported by NVivo software. RESULTS: Five broad and interrelated themes were identified: (1) Intensive Support; (2) The Severity of Patients' Illnesses; (3) Hope and Recovery; (4) Which Treatment When; (5) Limited Resources; and (6) Carer Burden. We identified various similarities between the two intensive treatment approaches, including the value of intensive and multidisciplinary support and carer involvement, and the challenge of managing complex and unique needs in resource-limited intensive settings. We also found differences in the relationship of treatment to patients' home environments, the necessity of patient motivation, and the management of risk. CONCLUSIONS: Both intensive treatment settings are valued by clinicians; however, there are unique challenges and opportunities for supporting individuals with severe AN within each. Our findings suggest DP treatment may be used as an alternative to IP treatment for individuals with severe AN. However, clear questions remain over which intensive treatment setting is best suited to which patient when and should be the focus of future research
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