2,371 research outputs found

    CMB Distortions from Superconducting Cosmic Strings

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    We reconsider the effect of electromagnetic radiation from superconducting strings on cosmic microwave background (CMB) mu- and y-distortions and derive present (COBE-FIRAS) and future (PIXIE) constraints on the string tension, mu_s, and electric current, I. We show that absence of distortions of the CMB in PIXIE will impose strong constraints on mu_s and I, leaving the possibility of light strings (G mu_s < 10^{-18}) or relatively weak currents (I < 10 TeV).Comment: 10pages, 5 figures, Submitted to PRD, v2:References added, replaced to match the PRD versio

    Polarization fluctuations due to extragalactic sources

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    We have derived the relationship between polarization and intensity fluctuations due to point sources. In the case of a Poisson distribution of a population with uniform evolution properties and constant polarization degree, polarization fluctuations are simply equal to intensity fluctuations times the average polarization degree. Conservative estimates of the polarization degree of the classes of extragalactic sources contributing to fluctuations in the frequency ranges covered by the forthcoming space missions MAP and Planck Surveyor indicate that extragalactic sources will not be a strong limiting factor to measurements of the polarization of the Cosmic Microwave Background.Comment: 15 pages LaTeX file, 3 postscript figures. Uses elsart.sty and elsart.cls Accepted for publication in New Astronom

    Optical Coherence Tomography Findings in Rhegmatogenous Retinal Detachment: A Systematic Review

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    Rhegmatogenous retinal detachment is a sight-threatening condition that may lead to blindness if left untreated. Surgical treatments may vary and are tailored to a single patient. Anatomical and functional results may vary, due to factors that are currently under study. Optical coherence tomography (OCT) allows a detailed visualization of the retinal structure. Some studies have been performed using OCT on eyes with retinal detachment. We performed a review on the subject. Several data have been obtained using different OCT applications. Some alterations may represent potential biomarkers since they are associated with visual and anatomical prognoses. Increased knowledge on the subject may be helpful to choose among different surgical strategies and endotamponades. More research on the topic is needed

    Cosmological Constraints on Neutrino Injection

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    We derive general constraints on the relic abundances of a long-lived particle which mainly decays into a neutrino (and something else) at cosmological time scales. Such an exotic particle may show up in various particle-physics models based on physics beyond the standard model. The constraints are obtained from big-bang nucleosynthesis, cosmic microwave background and diffuse neutrino and photon fluxes, depending on the lifetime and the electromagnetic and hadronic branching ratios.Comment: 33 pages, 23 figure

    Extragalactic Source Counts and Contributions to the Anisotropies of the Cosmic Microwave Background. Predictions for the Planck Surveyor mission

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    We present predictions for the counts of extragalactic sources, the contributions to fluctuations and their spatial power spectrum in each channel foreseen for the Planck Surveyor (formerly COBRAS/SAMBA) mission. The contribution to fluctuations due to clustering of both radio and far--IR sources is found to be generally small in comparison with the Poisson term; however the relative importance of the clustering contribution increases and may eventually become dominant if sources are identified and subtracted down to faint flux limits. The central Planck frequency bands are expected to be ``clean'': at high galactic latitude (|b|>20), where the reduced galactic noise does not prevent the detection of the extragalactic signal, only a tiny fraction of pixels is found to be contaminated by discrete extragalactic sources. Moreover, removal of contaminating signals is eased by the substantial difference between their power spectrum and that of primordial fluctuations.Comment: 10 pages, Latex, mn.sty, 8 figures included, MNRAS, in the press. Minor changes in the text. Sections 3.1 and 3.2 have been expanded. Source counts in Table 2 have been slightly changed. Figure 1,2,7 and 8 have been replaced by new version

    A New Method for ISOCAM Data Reduction - I. Application to the European Large Area ISO Survey Southern Field: Method and Results

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    We have developed a new data reduction technique for ISOCAM LW data and have applied it to the European Large Area ISO Survey (ELAIS) LW3 (15 micron) observations in the southern hemisphere (S1). This method, known as LARI technique and based on the assumption of the existence of two different time scales in ISOCAM transients (accounting either for fast or slow detector response), was particularly designed for the detection of faint sources. In the ELAIS S1 field we obtained a catalogue of 462 15 micron sources with signal-to-noise ratio >= 5 and flux densities in the range 0.45 - 150 mJy (filling the whole flux range between the Deep ISOCAM Surveys and the IRAS Faint Source Survey). The completeness at different flux levels and the photometric accuracy of this catalogue have been tested with simulations. Here we present a detailed description of the method and discuss the results obtained by its application to the S1 LW3 data.Comment: 20 pages, LaTeX, MNRAS style, 20 postscript figures, full catalogue not yet available at http://boas5.bo.astro.it/~elais/catalogues/. Accepted for publication in MNRA

    CARNITINE DEFICIENCY IN SCLERODERMA

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