3,296 research outputs found
Exoplanet Catalogues
One of the most exciting developments in the field of exoplanets has been the
progression from 'stamp-collecting' to demography, from discovery to
characterisation, from exoplanets to comparative exoplanetology. There is an
exhilaration when a prediction is confirmed, a trend is observed, or a new
population appears. This transition has been driven by the rise in the sheer
number of known exoplanets, which has been rising exponentially for two decades
(Mamajek 2016). However, the careful collection, scrutiny and organisation of
these exoplanets is necessary for drawing robust, scientific conclusions that
are sensitive to the biases and caveats that have gone into their discovery.
The purpose of this chapter is to discuss and demonstrate important
considerations to keep in mind when examining or constructing a catalogue of
exoplanets. First, we introduce the value of exoplanetary catalogues. There are
a handful of large, online databases that aggregate the available exoplanet
literature and render it digestible and navigable - an ever more complex task
with the growing number and diversity of exoplanet discoveries. We compare and
contrast three of the most up-to-date general catalogues, including the data
and tools that are available. We then describe exoplanet catalogues that were
constructed to address specific science questions or exoplanet discovery space.
Although we do not attempt to list or summarise all the published lists of
exoplanets in the literature in this chapter, we explore the case study of the
NASA Kepler mission planet catalogues in some detail. Finally, we lay out some
of the best practices to adopt when constructing or utilising an exoplanet
catalogue.Comment: 14 pages, 6 figures. Invited review chapter, to appear in "Handbook
of Exoplanets", edited by H.J. Deeg and J.A. Belmonte, section editor N.
Batalh
Fractal Profit Landscape of the Stock Market
We investigate the structure of the profit landscape obtained from the most
basic, fluctuation based, trading strategy applied for the daily stock price
data. The strategy is parameterized by only two variables, p and q. Stocks are
sold and bought if the log return is bigger than p and less than -q,
respectively. Repetition of this simple strategy for a long time gives the
profit defined in the underlying two-dimensional parameter space of p and q. It
is revealed that the local maxima in the profit landscape are spread in the
form of a fractal structure. The fractal structure implies that successful
strategies are not localized to any region of the profit landscape and are
neither spaced evenly throughout the profit landscape, which makes the
optimization notoriously hard and hypersensitive for partial or limited
information. The concrete implication of this property is demonstrated by
showing that optimization of one stock for future values or other stocks
renders worse profit than a strategy that ignores fluctuations, i.e., a
long-term buy-and-hold strategy.Comment: 12 pages, 4 figure
A survey of participants in two internet support groups for people with hair-pulling
BACKGROUND: A substantial number of patients suffering from psychological problems or psychiatric disorders have turned to internet support groups for help. This paper reports on the perceived effectiveness of trichotillomania (TTM) internet support groups for people suffering from hair-pulling. METHODS: A questionnaire was sent via e-mail to all subscribers of two mailing lists devoted to TTM, each of which takes a somewhat different approach to the condition. The questionnaire addressed the possible benefits and problems associated with belonging to a TTM virtual support group. RESULTS: Subscribers had similar demographic features as clinical samples of trichotillomania patients. Subscribers to both internet lists found them helpful in terms of feeling supported and in obtaining information. The different approaches to TTM on the two lists were associated with differences in treatments attempted by participants. CONCLUSION: Internet support groups can potentially contribute to increasing awareness about and knowledge of psychiatric disorders such as TTM, as well as to their management. Nevertheless, additional effort is required to ensure that subscribers are able to make informed, evidence-based decisions
Professional Development and the Informal Curriculum in End-of-Life Care
Although professionalism has emerged as a key competency for todayâs physicians, there exists little insight into how best to teach medical students the relevant skills or instill in them the commitment required to practice according to the highest professional standards. Ten UCSF medical students were interviewed at three time points (second, third, and fourth years of school). Interviews focused on studentsâ learning and development regarding end-of-life care (EOLC). Students described varying steps in their professional development from their second to fourth years of school, including feeling confused about the definition of professionalism and integrating their personal and professional identities. In addition to professional development, four other themes contributed to the development of medical student understanding of how to provide EOLC as a professional: (1) curricular discordance, (2) role models, (3) the tightrope between trained versus human reactions, and (4) ethical dilemmas. These five themes represent dilemmas that students often learned how to respond to over the course of school. Professional development in EOLC required the acquisition of skills necessary to balance the tension between and navigate conflicting messages present in medical student training
Psychometric precision in phenotype definition is a useful step in molecular genetic investigation of psychiatric disorders
Affective disorders are highly heritable, but few genetic risk variants have been consistently replicated in molecular genetic association studies. The common method of defining psychiatric phenotypes in molecular genetic research is either a summation of symptom scores or binary threshold score representing the risk of diagnosis. Psychometric latent variable methods can improve the precision of psychiatric phenotypes, especially when the data structure is not straightforward. Using data from the British 1946 birth cohort, we compared summary scores with psychometric modeling based on the General Health Questionnaire (GHQ-28) scale for affective symptoms in an association analysis of 27 candidate genes (249 single-nucleotide polymorphisms (SNPs)). The psychometric method utilized a bi-factor model that partitioned the phenotype variances into five orthogonal latent variable factors, in accordance with the multidimensional data structure of the GHQ-28 involving somatic, social, anxiety and depression domains. Results showed that, compared with the summation approach, the affective symptoms defined by the bi-factor psychometric model had a higher number of associated SNPs of larger effect sizes. These results suggest that psychometrically defined mental health phenotypes can reflect the dimensions of complex phenotypes better than summation scores, and therefore offer a useful approach in genetic association investigations
Do Doctors Vote?
BACKGROUND: Organizational leaders and scholars have issued calls for the medical profession to refocus its efforts on fulfilling the core tenets of professionalism. A key element of professionalism is participation in community affairs. OBJECTIVE: To measure physician voting rates as an indicator of civic participation. DESIGN: Cross-sectional survey of a subgroup of physicians from a nationally representative household survey of civilian, noninstitutionalized adult citizens. PARTICIPANTS: A total of 350,870 participants in the Current Population Survey (CPS) November Voter Supplement from 1996â2002, including 1,274 physicians and 1,886 lawyers; 414,989 participants in the CPS survey from 1976â1982, including 2,033 health professionals. MEASUREMENTS: Multivariate logistic regression models were used to compare adjusted physician voting rates in the 1996â2002 congressional and presidential elections with those of lawyers and the general population and to compare voting rates of health professionals in 1996â2002 with those in 1976â1992. RESULTS: After multivariate adjustment for characteristics known to be associated with voting rates, physicians were less likely to vote than the general population in 1998 (odds ratio 0.76; 95% confidence interval [CI] 0.59â0.99), 2000 (odds ratio 0.64; 95% CI 0.44â0.93), and 2002 (odds ratio 0.62; 95% CI 0.48â0.80) but not 1996 (odds ratio 0.83; 95% CI 0.59â1.17). Lawyers voted at higher rates than the general population and doctors in all four elections (Pâ<â.001). The pooled adjusted odds ratio for physician voting across the four elections was 0.70 (CI 0.61â0.81). No substantial changes in voting rates for health professionals were observed between 1976â1982 and 1996â2002. CONCLUSIONS: Physicians have lower adjusted voting rates than lawyers and the general population, suggesting reduced civic participation
A new durophagous scincomorphan lizard genus from the Late Cretaceous IharkĂșt locality (Hungary, Bakony Mts)
One-sided versus two-sided stochastic descriptions
It is well-known that discrete-time finite-state Markov Chains, which are
described by one-sided conditional probabilities which describe a dependence on
the past as only dependent on the present, can also be described as
one-dimensional Markov Fields, that is, nearest-neighbour Gibbs measures for
finite-spin models, which are described by two-sided conditional probabilities.
In such Markov Fields the time interpretation of past and future is being
replaced by the space interpretation of an interior volume, surrounded by an
exterior to the left and to the right.
If we relax the Markov requirement to weak dependence, that is, continuous
dependence, either on the past (generalising the Markov-Chain description) or
on the external configuration (generalising the Markov-Field description), it
turns out this equivalence breaks down, and neither class contains the other.
In one direction this result has been known for a few years, in the opposite
direction a counterexample was found recently. Our counterexample is based on
the phenomenon of entropic repulsion in long-range Ising (or "Dyson") models.Comment: 13 pages, Contribution for "Statistical Mechanics of Classical and
Disordered Systems
Collaborative research between clinicians and researchers: a multiple case study of implementation
<p>Abstract</p> <p>Background</p> <p>Bottom-up, clinician-conceived and directed clinical intervention research, coupled with collaboration from researcher experts, is conceptually endorsed by the participatory research movement. This report presents the findings of an evaluation of a program in the Veterans Health Administration meant to encourage clinician-driven research by providing resources believed to be critical. The evaluation focused on the extent to which funded projects: maintained integrity to their original proposals; were methodologically rigorous; were characterized by collaboration between partners; and resulted in sustained clinical impact.</p> <p>Methods</p> <p>Researchers used quantitative (survey and archival) and qualitative (focus group) data to evaluate the implementation, evaluation, and sustainability of four clinical demonstration projects at four sites. Fourteen research center mentors and seventeen clinician researchers evaluated the level of collaboration using a six-dimensional model of participatory research.</p> <p>Results</p> <p>Results yielded mixed findings. Qualitative and quantitative data suggested that although the process was collaborative, clinicians' prior research experience was critical to the quality of the projects. Several challenges were common across sites, including subject recruitment, administrative support and logistics, and subsequent dissemination. Only one intervention achieved lasting clinical effect beyond the active project period. Qualitative analyses identified barriers and facilitators and suggested areas to improve sustainability.</p> <p>Conclusions</p> <p>Evaluation results suggest that this participatory research venture was successful in achieving clinician-directed collaboration, but did not produce sustainable interventions due to such implementation problems as lack of resources and administrative support.</p
- âŠ