392 research outputs found
Quasar Black Hole Masses from Velocity Dispersions
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
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
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Water reuse for irrigated agriculture in Jordan: challenges of soil sustainability and the role of management strategies
Reclaimed water provides an important contribution to the water balance in water-scarce Jordan, but the quality of this water presents both benefits and challenges. Careful management of reclaimed water is required to maximize the nutrient benefits while minimizing the salinity risks. This work uses a multi-disciplinary research approach to show that soil response to irrigation with reclaimed water is a function of the management strategies adopted on the farm by the water user. The adoption of management methods to maintain soil productivity can be seen to be a result of farmers’ awareness to potentially plant-toxic ions in the irrigation water (70% of Jordan Valley farmers identified salinization as a hazard from irrigation with reclaimed water). However, the work also suggests that farmers’ management capacity is affected by the institutional management of water. About a third (35%) of farmers in the Jordan Valley claimed that their ability to manage salinization was limited by water shortages. Organizational interviews revealed that institutional awareness of soil management challenges was quite high (34% of interviewees described salinization as a risk from water reuse), but strategies to address this challenge at the institutional level require greater development
Dynamic multilateral markets
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
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
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
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
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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