14,804 research outputs found
Angular Power Spectra with Finite Counts
Angular anisotropy techniques for cosmic diffuse radiation maps are powerful
probes, even for quite small data sets. A popular observable is the angular
power spectrum; we present a detailed study applicable to any unbinned source
skymap S(n) from which N random, independent events are observed. Its exact
variance, which is due to the finite statistics, depends only on S(n) and N; we
also derive an unbiased estimator of the variance from the data. First-order
effects agree with previous analytic estimates. Importantly, heretofore
unidentified higher-order effects are found to contribute to the variance and
may cause the uncertainty to be significantly larger than previous analytic
estimates---potentially orders of magnitude larger. Neglect of these
higher-order terms, when significant, may result in a spurious detection of the
power spectrum. On the other hand, this would indicate the presence of
higher-order spatial correlations, such as a large bispectrum, providing new
clues about the sources. Numerical simulations are shown to support these
conclusions. Applying the formalism to an ensemble of Gaussian-distributed
skymaps, the noise-dominated part of the power spectrum uncertainty is
significantly increased at high multipoles by the new, higher-order effects.
This work is important for harmonic analyses of the distributions of diffuse
high-energy gamma-rays, neutrinos, and charged cosmic rays, as well as for
populations of sparse point sources such as active galactic nuclei.Comment: 27 pages, 8 figure
Computation of Superpotentials for D-Branes
We present a general method for the computation of tree-level superpotentials
for the world-volume theory of B-type D-branes. This includes quiver gauge
theories in the case that the D-brane is marginally stable. The technique
involves analyzing the A-infinity structure inherent in the derived category of
coherent sheaves. This effectively gives a practical method of computing
correlation functions in holomorphic Chern-Simons theory. As an example, we
give a more rigorous proof of previous results concerning 3-branes on certain
singularities including conifolds. We also provide a new example.Comment: 28 page
The Galactic Isotropic -ray Background and Implications for Dark Matter
We present an analysis of the radial angular profile of the galacto-isotropic
(GI) -ray flux--the statistically uniform flux in circular annuli about
the Galactic center. Two different approaches are used to measure the GI flux
profile in 85 months of Fermi-LAT data: the BDS statistic method which
identifies spatial correlations, and a new Poisson ordered-pixel method which
identifies non-Poisson contributions. Both methods produce similar GI flux
profiles. The GI flux profile is well-described by an existing model of
bremsstrahlung, production, inverse Compton scattering, and the
isotropic background. Discrepancies with data in our full-sky model are not
present in the GI component, and are therefore due to mis-modeling of the
non-GI emission. Dark matter annihilation constraints based solely on the
observed GI profile are close to the thermal WIMP cross section below 100 GeV,
for fixed models of the dark matter density profile and astrophysical
-ray foregrounds. Refined measurements of the GI profile are expected
to improve these constraints by a factor of a few.Comment: 20 pages, 15 figures, references adde
For the good of the group? Exploring group-level evolutionary adaptations using multilevel selection theory.
In this paper, we present an evolutionary framework, multilevel selection theory (MLS), that is highly amenable to existing social psychological theory and empiricism. MLS provides an interpretation of natural selection that shows how group-beneficial traits can evolve, a prevalent implication of social psychological data. We outline the theory and provide a number of example topics, focusing on prosociality, policing behavior, gossip, brainstorming, distributed cognition, and social identity. We also show that individual differences can produce important group-level outcomes depending on differential aggregation of individual types and relate this to the evolutionary dynamics underlying group traits. Drawing on existing work, we show how social psychologists can integrate this framework into their research program and suggest future directions for research
Routine administration of Health Related Quality of Life (HRQoL) and needs assessment instruments to improve psychological outcome: a systematic review
Background. Routine administration of Health Related Quality of Life (HRQoL) and needs assessment instruments has been advocated as part of clinical care to aid the recognition of psychosocial problems, to inform clinical decision making, to monitor therapeutic response and to facilitate patient-doctor communication. However, their adoption is not without cost and the benefit of their use is unclear. Method. A systematic review was conducted. We sought experimental studies that examined the addition of routinely administered measures of HRQoL to care in both psychiatric and non-psychiatric settings. We searched the following databases: MEDLINE, EMBASE, CINAHL, PsycLIT and Cochrane Controlled Trials Register (to 2000). Data were extracted independently and a narrative synthesis of results was presented. Results. Nine randomized and quasi-randomized studies conducted in non-psychiatric settings were found. All the instruments used included an assessment of mental well-being, with specific questions relating to depression and anxiety. The routine feedback of these instruments had little impact on the recognition of mental disorders or on longer term psychosocial functioning. While clinicians welcomed the information these instruments imparted, their results were rarely incorporated into routine clinical decision making. No studies were found that examined the value of routine assessment and feedback of HRQoL or patient needs in specialist psychiatric care settings. Conclusions. Routine HRQoL measurement is a costly exercise and there is no robust evidence to suggest that it is of benefit in improving psychosocial outcomes of patients managed in non-psychiatric settings. Major policy initiatives to increase the routine collection and use of outcome measures in psychiatric settings are unevaluated
Routinely administered questionnaires for depression and anxiety : systematic review
Objectives To examine the effect of routinely administered psychiatric questionnaires on the recognition, management, and outcome of psychiatric disorders in non-psychiatric settings. Data sources Embase, Medline, PsycLIT, Cinahl, Cochrane Controlled Trials Register,and hand searches of key journals. Methods A systematic review of randomised controlled trials of the administration and routine feedback of psychiatric screening and outcome questionnaires to clinicians in non-psychiatric settings. narrative overview of key design features and end points, together with a random effects quantitative synthesis of comparable studies. Main outcome measures Recognition of psychiatric disorders after feedback of questionnaire results; interventions for psychiatric disorders and outcome of psychiatric disorders. Results Nine randomised studies were identified that examined the use of common psychiatric instruments in primary care and general hospital settings. Studies compared the effect of the administration of these instruments followed by the feedback of the results to clinicians, with administration with no feedback. Meta-analytic pooling was possible for four of these studies (2457 participants), which measured the effect of feedback on the recognition of depressive disorders. Routine administration and feedback of scores for all patients (irrespective of score) did not increase the overall rate of recognition of mental disorders such as anxiety and depression (relative risk of detection of depression by clinician after feedback 0.95, 95% confidence interval 0.83 to 1.09). Two studies showed that routine administration followed by selective feedback for only high scores increased the rate of recognition of depression (relative risk of detection of depression after feedback 2.64, 1.62 to 4.31). This increased recognition, however, did not translate into an increased rate of intervention. Overall, studies of routine administration of psychiatric measures did not show an effect on patient outcome. Conclusions The routine measurement of outcome is a costly exercise. Little evidence shows that it is of benefit in improving psychosocial outcomes of those with psychiatric disorder managed in non-psychiatric settings
Dark matter indirect detection signals and the nature of neutrinos in the supersymmetric extension of the standard model
In this paper, we study the prospects for determining the nature of neutrinos
in the context of a supersymmetric extension of the standard model by
using dark matter indirect detection signals and bounds on
from the cosmic microwave background data. The model contains two new dark
matter candidates whose dominant annihilation channels produce more neutrinos
than neutralino dark matter in the minimal supersymmetric standard model. The
photon and neutrino counts may then be used to discriminate between the two
models. If the dark matter comes from the B-L sector, its indirect signals and
impact on the cosmic microwave background can shed light on the nature of the
neutrinos. When the light neutrinos are of Majorana type, the indirect neutrino
signal from the Sun and the galactic center may show a prompt neutrino
box-feature, as well as an earlier cut-off in both neutrino and gamma ray
energy spectra. When the light neutrinos are of Dirac type, their contribution
to the effective number of neutrinos is at a detectable level.Comment: 11 pages, 3 figures, 2 table
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