589 research outputs found
High Energy Positrons From Annihilating Dark Matter
Recent preliminary results from the PAMELA experiment indicate the presence
of an excess of cosmic ray positrons above 10 GeV. In this letter, we consider
possibility that this signal is the result of dark matter annihilations taking
place in the halo of the Milky Way. Rather than focusing on a specific particle
physics model, we take a phenomenological approach and consider a variety of
masses and two-body annihilation modes, including W+W-, ZZ, b bbar, tau+ tau-,
mu+ mu-, and e+e. We also consider a range of diffusion parameters consistent
with current cosmic ray data. We find that a significant upturn in the positron
fraction above 10 GeV is compatible with a wide range of dark matter
annihilation modes, although very large annihilation cross sections and/or
boost factors arising from inhomogeneities in the local dark matter
distribution are required to produce the observed intensity of the signal. We
comment on constraints from gamma rays, synchrotron emission, and cosmic ray
antiproton measurements.Comment: 4 pages, 1 figur
No Indications of Axion-Like Particles From Fermi
As very high energy (~100 GeV) gamma rays travel over cosmological distances,
their flux is attenuated through interactions with the extragalactic background
light. Observations of distant gamma ray sources at energies between ~200 GeV
and a few TeV by ground-based gamma ray telescopes such as HESS, however,
suggest that the universe is more transparent to very high energy photons than
had been anticipated. One possible explanation for this is the existence of
axion-like-particles (ALPs) which gamma rays can efficiently oscillate into,
enabling them to travel cosmological distances without attenuation. In this
article, we use data from the Fermi Gamma Ray Space Telescope to calculate the
spectra at 1-100 GeV of two gamma ray sources, 1ES1101-232 at redshift z=0.186
and H2356-309 at z=0.165, and use this in conjunction with the measurements of
ground-based telescopes to test the ALP hypothesis. We find that the
observations can be well-fit by an intrinsic power-law source spectrum with
indices of -1.72 and -2.1 for 1ES1101-232 and H2356-309, respectively, and that
no ALPs or other exotic physics is necessary to explain the observed degree of
attenuation.Comment: 7 pages, 4 figures. v3: Matches published version, the analysis of
H2356-309 is revised, no change in conclusion
Contemplating E-Scores: Open Ruminations on the E-Score, the Patron, the Library, and the Publisher
For several years now, libraries, publishers, and vendors have worked out a means of creating, licensing, and delivering e-books in academic settings. While the art of the academic e-book is perhaps not quite yet perfected, conservatively speaking, today’s students and faculty will find and use at least one e-book in the course of their academic career and be more or less satisfied with the experience. E-scores, however, are only now coming to occupy the attention of librarians and not a moment too soon as commercial e-score vendors with subpar quality content manage to meet the functionality needs of most users. Many living composers are harnessing the Internet and cutting out the middle man by offering e-scores in the form of downloadable PDFs. Score publishers are, by and large, still in the early stages of thinking about moving to e-score format (also for personal downloads), and vendors with e-score platforms are negligible. This paper opened the conversation about e-scores to acquisition librarians, e-book publishers, and vendors who typically work outside the music library.
The first half of this paper provides an overview of the current state of e-scores in academic libraries, including what patrons want from e-scores, what score publishers are doing, what libraries are currently able to provide, and, finally, what commercial vendors are already doing. The final portion of the paper briefly reviews responses from the conference session audience. Through this open questioning, it is hoped that readers will come to new understandings of their own work with other electronic materials, while at the same time bring their expertise to bear on the future of e-score development
Systematic review and network meta-analysis with individual participant data on cord management at preterm birth (iCOMP): study protocol
Introduction
Timing of cord clamping and other cord management strategies may improve outcomes at preterm birth. However, it is unclear whether benefits apply to all preterm subgroups. Previous and current trials compare various policies, including time-based or physiology-based deferred cord clamping, and cord milking. Individual participant data (IPD) enable exploration of different strategies within subgroups. Network meta-analysis (NMA) enables comparison and ranking of all available interventions using a combination of direct and indirect comparisons.
Objectives
(1) To evaluate the effectiveness of cord management strategies for preterm infants on neonatal mortality and morbidity overall and for different participant characteristics using IPD meta-analysis. (2) To evaluate and rank the effect of different cord management strategies for preterm births on mortality and other key outcomes using NMA.
Methods and analysis
Systematic searches of Medline, Embase, clinical trial registries, and other sources for all ongoing and completed randomised controlled trials comparing cord management strategies at preterm birth (before 37 weeks’ gestation) have been completed up to 13 February 2019, but will be updated regularly to include additional trials. IPD will be sought for all trials; aggregate summary data will be included where IPD are unavailable. First, deferred clamping and cord milking will be compared with immediate clamping in pairwise IPD meta-analyses. The primary outcome will be death prior to hospital discharge. Effect differences will be explored for prespecified participant subgroups. Second, all identified cord management strategies will be compared and ranked in an IPD NMA for the primary outcome and the key secondary outcomes. Treatment effect differences by participant characteristics will be identified. Inconsistency and heterogeneity will be explored.
Ethics and dissemination
Ethics approval for this project has been granted by the University of Sydney Human Research Ethics Committee (2018/886). Results will be relevant to clinicians, guideline developers and policy-makers, and will be disseminated via publications, presentations and media releases
A New Approach to Searching for Dark Matter Signals in Fermi-LAT Gamma Rays
Several cosmic ray experiments have measured excesses in electrons and
positrons, relative to standard backgrounds, for energies from ~ 10 GeV - 1
TeV. These excesses could be due to new astrophysical sources, but an
explanation in which the electrons and positrons are dark matter annihilation
or decay products is also consistent. Fortunately, the Fermi-LAT diffuse gamma
ray measurements can further test these models, since the electrons and
positrons produce gamma rays in their interactions in the interstellar medium.
Although the dark matter gamma ray signal consistent with the local electron
and positron measurements should be quite large, as we review, there are
substantial uncertainties in the modeling of diffuse backgrounds and,
additionally, experimental uncertainties that make it difficult to claim a dark
matter discovery. In this paper, we introduce an alternative method for
understanding the diffuse gamma ray spectrum in which we take the intensity
ratio in each energy bin of two different regions of the sky, thereby canceling
common systematic uncertainties. For many spectra, this ratio fits well to a
power law with a single break in energy. The two measured exponent indices are
a robust discriminant between candidate models, and we demonstrate that dark
matter annihilation scenarios can predict index values that require "extreme"
parameters for background-only explanations.Comment: v1: 11 pages, 7 figures, 1 table, revtex4; v2: 13 pages, 8 figures, 1
table, revtex4, Figure 4 added, minor additions made to text, references
added, conclusions unchanged, published versio
Katrina Works: A Bibliography of Musical Works Composed in Response to Hurricane Katrina
A bibliography of art music composed in response to Hurricane Katrina from 2005-2015
Expanding the discussion regarding parentification and its varied outcomes: Implications for mental health research and practice
'Ain't it a Ripping Night': Alcoholism and the Legacies of Empire in Salman Rushdie's Midnight's Children.
In the era of decolonisation that followed the Second World War, various authors sought to engage with India and the Empire’s past anew throughout their novels, identifying medicine and illness as key parts of Imperial authority and colonial experience. Salman Rushdie’s approach to the Raj in Midnight’s Children (1981) focused on the broad sweep of colonial life, juxtaposing the political and the personal. This article argues that Rushdie explores the history of colonial India by employing alcohol and alcoholism as lenses through which to explore the cultural, political and medical legacies of Empire. Through analysis of Midnight’s Children as well as a range of medical sources related to alcohol and inebriation, it will illustrate how drinking is central to Rushdie’s approach to secular and religious identities in newly independent India, as well as a means of satirising and undermining the supposed benefit that Empire presented to India and Indians
ASSESSING FAMILY CAREGIVING: A COMPARISON OF THREE RETROSPECTIVE PARENTIFICATION MEASURES
Despite the frequent use of the Parentification Questionnaire (PQ) and the Parentification Scale (PS) in research studies, scant attention has been directed toward the psychometric properties of the scores derived from these measures. Moreover, given the importance of parentification as a clinical topic for treatment, it is surprising that more attention has not been paid to the accuracy and psychometric properties of parentification instruments. The current study was the first to compare the psychometric properties of these two commonly used parentification instruments (i.e., PQ and PS). This study also examined another parentification instrument, newly developed: the Parentification Inventory (PI). More specifically, the psychometric properties of the PI were compared comprehensively with those of the PQ and PS in a sample of college students (N = 787). Scores derived from the three measures were found to be comparable, valid, and reliable. Implications for couple and family system practice, and directions for future research are proffered
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