Men Experiencing Homelessness: A Qualitative Investigation of Multiple Stigmas

Homelessness is a pervasive and problematic phenomenon. Unfortunately, programs designed to reduce or eliminate homelessness face a number of challenges. One such challenge involves difficulty engaging and retaining clientele who are experiencing homelessness in services. The literature suggests that one explanation for this difficulty involves the stigmatization experiences that individuals who are homeless accumulate over time. However, the relationship between stigmatization and the psychosocial functioning of individuals facing homelessness has rarely been investigated empirically, and it is unclear how well various theories of stigma apply to this unique population. The purpose of the current paper is to propose a grounded theory study of how a specific subgroup of the homeless population experiences and responds to multiple sources of social stigmatization: African American men experiencing homelessness and facing co-occurring mental illness and substance use disorders

Evaluating the stability of atmospheric lines with HARPS

Context: In the search for extrasolar systems by radial velocity technique, a precise wavelength calibration is necessary for high-precision measurements. The choice of the calibrator is a particularly important question in the infra-red domain, where the precision and exploits still fall behind the achievements of the optical. Aims: We investigate the long-term stability of atmospheric lines as a precise wavelength reference and analyze their sensitivity to different atmospheric and observing conditions. Methods: We use HARPS archive data on three bright stars, Tau Ceti, Mu Arae and Epsilon Eri, spanning 6 years and containing high-cadence measurements over several nights. We cross-correlate this data with an O2 mask and evaluate both radial velocity and bisector variations down to a photon noise of 1 m/s. Results: We find that the telluric lines in the three data-sets are stable down to 10 m/s (r.m.s.) over the 6 years. We also show that the radial velocity variations can be accounted for by simple atmospheric models, yielding a final precision of 1-2 m/s. Conclusions: The long-term stability of atmospheric lines was measured as being of 10 m/s over six years, in spite of atmospheric phenomena. Atmospheric lines can be used as a wavelength reference for short-time-scales programs, yielding a precision of 5 m/s "out-of-the box". A higher precision, down to 2 m/s can be reached if the atmospheric phenomena are corrected for by the simple atmospheric model described, making it a very competitive method even on long time-scales.Comment: 7 pages, accepted for publication in A&

Signal buffering in random networks of spiking neurons: microscopic vs. macroscopic phenomena

In randomly connected networks of pulse-coupled elements a time-dependent input signal can be buffered over a short time. We studied the signal buffering properties in simulated networks as a function of the networks state, characterized by both the Lyapunov exponent of the microscopic dynamics and the macroscopic activity derived from mean-field theory. If all network elements receive the same signal, signal buffering over delays comparable to the intrinsic time constant of the network elements can be explained by macroscopic properties and works best at the phase transition to chaos. However, if only 20 percent of the network units receive a common time-dependent signal, signal buffering properties improve and can no longer be attributed to the macroscopic dynamics.Comment: 5 pages, 3 figure

Conformal and gauge invariant spin-2 field equations

Using an approach based on the Casimir operators of the de Sitter group, the conformal invariant equations for a fundamental spin-2 field are obtained, and their consistency discussed. It is shown that, only when the spin-2 field is interpreted as a 1-form assuming values in the Lie algebra of the translation group, rather than a symmetric second-rank tensor, the field equation is both conformal and gauge invariant.Comment: 12 pages, no figures; accepted for publication in Gravitation & Cosmolog

African American Men Facing Homelessness and Co-occurring Disorders: A Qualitative Investigation of Multiple Stigmas

Homelessness is a pervasive and problematic phenomenon, and programs designed to assist individuals experiencing homelessness and reduce homelessness face a number of challenges. One such challenge involves difficulty engaging and retaining clientele experiencing homelessness in supportive services (Bhui et al., 2006; Ng & McQuistion, 2004; Padgett et al., 2008). The literature suggests that one explanation for this difficulty may involve the stigmatization experiences that individuals facing homelessness accumulate over time; previous studies have indicated that holding a marginalized position in society may make individuals experiencing homelessness more reluctant to engage in services (because of social rejection fears) and/or more sensitive to injustices that sometimes occur within homeless assistance programs (Bhui et al., 2006; Kim et al., 2007; Leipersberger, 2007; Padgett et al., 2008). However, the overall relationship between stigmatization and the psychosocial functioning of individuals facing homelessness has rarely been investigated empirically. The purpose of the current study, therefore, was to explore how a specific subgroup of the homeless population experiences and responds to multiple sources of stigmatization: African American men facing chronic homelessness and co-occurring mental illness and substance use disorders. Grounded theory research methodology (Corbin & Strauss, 2008) was used to examine this topic from the perspective of men participating in mental health/substance-related counseling at a homeless shelter and maintaining abstinence from alcohol and drugs. Twelve men participated in individual interviews during which they were asked to discuss their experiences being stigmatized, the perceived impact of stigmatization on their psychosocial functioning, coping strategies they employ in response to stigmatization, and treatment-seeking behaviors. Results revealed that (a) the participants have been multiply stigmatized, (b) they perceive the stigma of homelessness as the most difficult stigma with which to contend, and (c) they believe it is more difficult to be stigmatized for multiple reasons than for a single reason alone. Results also indicated that the impact of stigmatization on the participants\u27 lives has changed over time (from disempowerment to empowerment) and that the participants have altered their stigmatization coping strategies (from unhelpful and destructive to helpful and constructive). Findings, implications, and limitations of the current study are discussed. Directions for future research are recommended

Abundance ratios of volatile vs. refractory elements in planet-harbouring stars: hints of pollution?

We present the [X/H] trends as function of the elemental condensation temperature Tc in 88 planet host stars and in a volume-limited comparison sample of 33 dwarfs without detected planetary companions. We gathered homogeneous abundance results for many volatile and refractory elements spanning a wide range of Tc, from a few dozens to several hundreds kelvin. We investigate possible anomalous trends of planet hosts with respect to comparison sample stars in order to detect evidence of possible pollution events. No significant differences are found in the behaviour of stars with and without planets. This result is in agreement with a ``primordial'' origin of the metal excess in planet host stars. However, a subgroup of 5 planet host and 1 comparison sample stars stands out for having particularly high [X/H] vs. Tc slopes.Comment: 10 pages, 7 figures, accepted for publication in A&A. Figures with higher resolution are available at www.iac.es/proyect/abuntes

Comparing HARPS and Kepler surveys: The alignment of multiple-planet systems

Aims. We study a subset of the planetary population characterized both by HARPS and Kepler surveys. We compare the statistical properties of planets in systems with m.sin i >5-10 M_Earth and R>2 R_Earth. If we assume that the underlying population has the same characteristics, the different detection sensitivity to the orbital inclination relative to the line of sight allows us to probe the planets' mutual inclination. Methods. We considered the frequency of systems with one, two and three planets as dictated by HARPS data. We used Kepler's planetary period and host mass and radii distributions (corrected from detection bias) to model planetary systems in a simple yet physically plausible way. We then varied the mutual inclination between planets in a system according to different prescriptions (completely aligned, Rayleigh distributions and isotropic) and compared the transit frequencies with one, two or three planets with those measured by Kepler. Results. The results show that the two datasets are compatible, a remarkable result especially because there are no tunable knobs other than the assumed inclination distribution. For m.sin i cutoffs of 7-10 M_Earth, which are those expected to correspond to the radius cutoff of 2 R_Earth, we conclude that the results are better described by a Rayleigh distribution with mode of 1 deg or smaller. We show that the best-fit scenario only becomes a Rayleigh distribution with mode of 5 deg if we assume a rather extreme mass-radius relationship for the planetary population. Conclusions. These results have important consequences for our understanding of the role of several proposed formation and evolution mechanisms. They confirm that planets are likely to have been formed in a disk and show that most planetary systems evolve quietly without strong angular momentum exchanges (abridged).Comment: 10 pages, 6 figures, 4 tables, accepted for publication in Astronomy & Astrophysic

Radial Velocities with CRIRES: Pushing precision down to 5-10 m/s

With the advent of high-resolution infrared spectrographs, Radial Velocity (RV) searches enter into a new domain. As of today, the most important technical question to address is which wavelength reference is the most suitable for high-precision RV measurements. In this work we explore the usage of atmospheric absorption features. We make use of CRIRES data on two programs and three different targets. We re-analyze the data of the TW Hya campaign, reaching a dispersion of about 6 m/s on the RV standard in a time scale of roughly 1 week. We confirm the presence of a low-amplitude RV signal on TW Hya itself, roughly 3 times smaller than the one reported at visible wavelengths. We present RV measurements of Gl 86 as well, showing that our approach is capable of detecting the signal induced by a planet and correctly quantifying it. Our data show that CRIRES is capable of reaching a RV precision of less than 10 m/s in a time-scale of one week. The limitations of this particular approach are discussed, and the limiting factors on RV precision in the IR in a general way. The implications of this work on the design of future dedicated IR spectrographs are addressed as well.Comment: 9 pages, accepted for publication in A&

Ontological realism, concepts and classification in molecular biology: Development and application of the gene ontology

Purpose – The purpose of this article is to evaluate the development and use of the gene ontology (GO), a scientific vocabulary widely used in molecular biology databases, with particular reference to the relation between the theoretical basis of the GO, and the pragmatics of its application. Design/methodology/approach – The study uses a combination of bibliometric analysis, content analysis and discourse analysis. These analyses focus on details of the ways in which the terms of the ontology are amended and deleted, and in which they are applied by users. Findings – Although the GO is explicitly based on an objective realist epistemology, a considerable extent of subjectivity and social factors are evident in its development and use. It is concluded that bio-ontologies could beneficially be extended to be pluralist, while remaining objective, taking a view of concepts closer to that of more traditional controlled vocabularies. Originality/value – This is one of very few studies which evaluate the development of a formal ontology in relation to its conceptual foundations, and the first to consider the GO in this way

On the functional form of the metallicity-giant planet correlation

It is generally accepted that the presence of a giant planet is strongly dependent on the stellar metallicity. A stellar mass dependence has also been investigated, but this dependence does not seem as strong as the metallicity dependence. Even for metallicity, however, the exact form of the correlation has not been established. In this paper, we test several scenarios for describing the frequency of giant planets as a function of its host parameters. We perform this test on two volume-limited samples (from CORALIE and HARPS). By using a Bayesian analysis, we quantitatively compared the different scenarios. We confirm that giant planet frequency is indeed a function of metallicity. However, there is no statistical difference between a constant or an exponential function for stars with subsolar metallicities contrary to what has been previously stated in the literature. The dependence on stellar mass could neither be confirmed nor be discarded.Comment: 5 pages, 2 figures, accepted in A&