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

The Galactic Isotropic γ\gamma-ray Background and Implications for Dark Matter

We present an analysis of the radial angular profile of the galacto-isotropic (GI) $\gamma$-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, $\pi^0$ 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 $\gamma$-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

Dark matter indirect detection signals and the nature of neutrinos in the supersymmetric U(1)B−LU(1)_{B-L} extension of the standard model

In this paper, we study the prospects for determining the nature of neutrinos in the context of a supersymmetric $B-L$ extension of the standard model by using dark matter indirect detection signals and bounds on $N_{\text{eff}}$ 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 $N_{\text{eff}}$ is at a detectable level.Comment: 11 pages, 3 figures, 2 table

Light Curves for Rapidly-Rotating Neutron Stars

We present raytracing computations for light emitted from the surface of a rapidly-rotating neutron star in order to construct light curves for X-ray pulsars and bursters. These calculations are for realistic models of rapidly-rotating neutron stars which take into account both the correct exterior metric and the oblate shape of the star. We find that the most important effect arising from rotation comes from the oblate shape of the rotating star. We find that approximating a rotating neutron star as a sphere introduces serious errors in fitted values of the star's radius and mass if the rotation rate is very large. However, in most cases acceptable fits to the ratio M/R can be obtained with the spherical approximation.Comment: Accepted by the Astrophysical Journal. 13 pages & 7 figure

Extragalactic and galactic gamma-rays and neutrinos from annihilating dark matter

We describe cosmic gamma-ray and neutrino signals of dark matter annihilation, explaining how the complementarity of these signals provides additional information that, if observable, can enlighten the particle nature of dark matter. This is discussed in the context of exploiting the separate galactic and extragalactic components of the signal, using the spherical halo model distribution of dark matter. We motivate the discussion with supersymmetric extensions of the standard model of particle physics. We consider the minimal supersymmetric standard model (MSSM) where both neutrinos and gamma-rays are produced from annihilations. We also consider a gauged B-L, baryon number minus lepton number, extension of the MSSM, where annihilation can be purely to heavy right-handed neutrinos. We compare the galactic and extragalactic components of these signals, and conclude that it is not yet clear which may dominate when looking out of the galactic plane. To answer this question, we must have an understanding of the contribution of halo substructure to the annihilation signals. We find that different theories with indistinguishable gamma-ray signals can be distinguished in the neutrino signal. Gamma-ray annihilation signals are difficult to observe from the galactic center, due to abundant astrophysical sources; but annihilation neutrinos from there would not be so hidden, if they can be observed over the atmospheric neutrinos produced by cosmic rays.Comment: 15 pages, 11 figure

Communication between secondary and primary care following self-harm: are National Institute of Clinical Excellence (NICE) guidelines being met?

<p>Abstract</p> <p>Background</p> <p>Most patients contact their general practitioner (GP) following presentation to an Emergency Department (ED) after a self-harm incident, and strategies to help GPs manage these patients include efficient communication between services. The aim of this study was to assess the standard of documentation and communication to primary care from secondary care as recommended by the National Institute of Clinical Excellence (NICE) guidelines on the short-term management of people who self-harm.</p> <p>Methods</p> <p>An audit of medical records (ED and Psychiatric) on people aged 16 years and over who had presented to the ED following self-harm, benchmarked according to government guidelines, was performed. Data were collected over a 4-week period at a general teaching hospital.</p> <p>Results</p> <p>We collected data on 93 consecutive episodes of self-harm; 62% of episodes were communicated to primary care, 58% of these communications were within 24 h and most within 3 days. Patient identifying details and follow-up arrangements were specified in most cases. Communication via psychiatric staff was most detailed. ED clinicians provided few communications and were of limited content. Communication with the patient's GP was not made in half of those cases seen by a mental health specialist.</p> <p>Conclusion</p> <p>Government guidelines are only partially being met. Reliance on communication by ED staff would leave a substantial proportion of patients discharged from the ED with no or minimal communication to primary care. Psychiatric services need to improve the rate of communication to the patient's GP following assessment A national sample of National Health Service (NHS) trusts would establish if this is a problem elsewhere.</p

Communication between secondary and primary care following self-harm: are National Institute of Clinical Excellence (NICE) guidelines being met?

<p>Abstract</p> <p>Background</p> <p>Most patients contact their general practitioner (GP) following presentation to an Emergency Department (ED) after a self-harm incident, and strategies to help GPs manage these patients include efficient communication between services. The aim of this study was to assess the standard of documentation and communication to primary care from secondary care as recommended by the National Institute of Clinical Excellence (NICE) guidelines on the short-term management of people who self-harm.</p> <p>Methods</p> <p>An audit of medical records (ED and Psychiatric) on people aged 16 years and over who had presented to the ED following self-harm, benchmarked according to government guidelines, was performed. Data were collected over a 4-week period at a general teaching hospital.</p> <p>Results</p> <p>We collected data on 93 consecutive episodes of self-harm; 62% of episodes were communicated to primary care, 58% of these communications were within 24 h and most within 3 days. Patient identifying details and follow-up arrangements were specified in most cases. Communication via psychiatric staff was most detailed. ED clinicians provided few communications and were of limited content. Communication with the patient's GP was not made in half of those cases seen by a mental health specialist.</p> <p>Conclusion</p> <p>Government guidelines are only partially being met. Reliance on communication by ED staff would leave a substantial proportion of patients discharged from the ED with no or minimal communication to primary care. Psychiatric services need to improve the rate of communication to the patient's GP following assessment A national sample of National Health Service (NHS) trusts would establish if this is a problem elsewhere.</p

Challenges to undertaking randomised trials with looked after children in social care settings.

BACKGROUND: Randomised controlled trials (RCTs) are widely viewed as the gold standard for assessing effectiveness in health research; however many researchers and practitioners believe that RCTs are inappropriate and un-doable in social care settings, particularly in relation to looked after children. The aim of this article is to describe the challenges faced in conducting a pilot study and phase II RCT of a peer mentoring intervention to reduce teenage pregnancy in looked after children in a social care setting. METHODS: Interviews were undertaken with social care professionals and looked after children, and a survey conducted with looked after children, to establish the feasibility and acceptability of the intervention and research design. RESULTS: Barriers to recruitment and in managing the intervention were identified, including social workers acting as informal gatekeepers; social workers concerns and misconceptions about the recruitment criteria and the need for and purpose of randomisation; resource limitations, which made it difficult to prioritise research over other demands on their time and difficulties in engaging and retaining looked after children in the study. CONCLUSIONS: The relative absence of a research infrastructure and culture in social care and the lack of research support funding available for social care agencies, compared to health organisations, has implications for increasing evidence-based practice in social care settings, particularly in this very vulnerable group of young people