994 research outputs found

    Time-varying neutrino mass from a supercooled phase transition: current cosmological constraints and impact on the Ωm\Omega_m-σ8\sigma_8 plane

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    In this paper we investigate a time-varying neutrino mass model, motivated by the mild tension between cosmic microwave background (CMB) measurements of the matter fluctuations and those obtained from low-redshift data. We modify the minimal case of the model proposed by Dvali and Funcke (2016) that predicts late neutrino mass generation in a post-recombination cosmic phase transition, by assuming that neutrino asymmetries allow for the presence of relic neutrinos in the late-time Universe. We show that, if the transition is supercooled, current cosmological data (including CMB temperature, polarization and lensing, baryon acoustic oscillations, and Type Ia supernovae) prefer the scale factor asa_s of the phase transition to be very large, peaking at as1a_s\sim 1, and therefore supporting a cosmological scenario in which neutrinos are almost massless until very recent times. We find that in this scenario the cosmological bound on the total sum of the neutrino masses today is significantly weakened compared to the standard case of constant-mass neutrinos, with mν<4.8\sum m_\nu<4.8~eV at 95\% confidence, and in agreement with the model predictions. The main reason for this weaker bound is a large correlation arising between the dark energy and neutrino components in the presence of false vacuum energy that converts into the non-zero neutrino masses after the transition. This result provides new targets for the coming KATRIN and PTOLEMY experiments. We also show that the time-varying neutrino mass model considered here does not provide a clear explanation to the existing cosmological Ωm\Omega_m-σ8\sigma_8 discrepancies.Comment: 13 pages, 13 figures, matches updated version accepted by Physical Review

    The role of Virus "X" (Tortoise Picornavirus) in kidney disease and shell weakness syndrome in European tortoise species determined by experimental infection

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    Tortoise Picornavirus (ToPV) commonly known as Virus "X" was recently discovered in juvenile European tortoises suffering from soft carapace and plastron as well as kidney disease. Therefore, this virus was a potential candidate to be a causative agent for these disease patterns. Spur thighed tortoises (Testudo graeca) seemed to be more susceptible to establish clinical symptoms than other European species like T. hermanni. Thus this trial investigated the role of ToPV in the described syndrome. Two groups of juvenile European tortoises (T. graeca and T.hermanni) each of 10 animals, were cloacally, oronasally and intracoelomically inoculated with an infectious dose (~ 2000 TICD) of a ToPV strain isolated from a diseased T. graeca. A control group of two animals of each species received non-infected cell culture supernatant. The tortoises were examined daily and pharyngeal and cloacal swabs for detection of ToPV-RNA by RT-PCR were taken from each animal every six days for a period of 6 months. At the end of the study the remaining animals were euthanised and dissected. Bacteriological and parasitological tests were performed and organ samples of all tortoises were investigated by RT-PCR for the presence of ToPV and histopathology. Animals that were euthanised at the end of the experiment, were examined for presence of specific anti-ToPV antibodies. Several animals in both inoculated groups showed retarded growth and a light shell weakness, in comparison to the control animals. Three animals were euthanised during the trial, showing reduced weight gain, retarded growth, severe shell weakness and apathy, in parallel to clinical observations in naturally infected animals. In all inoculated animals of both species an intermittent virus shedding, starting from 18 days post inoculation (d.p.i.), till 164 d.p.i. was detected, while the control animals remained negative. The virus was successfully reisolated in terrapene heart cell culture in 16 of 20 inoculated animals of both species. Histopathology of most inoculated animals revealed a lack of bone remodeling and vacuolisation in kidney tubuli which supports the described pathogenesis of nephropathy and osteodystrophy. Anti- ToPV antibody titres ranged from 1:2 to >1:256 in 13 of 20 animals, whereas all control animals were seronegative. The study proofed the Henle Koch`s postulates of ToPV as causative agent for shell dystrophy and kidney disease in both testudo species. The proposed species specific sensitivity towards clinical disease was not observed

    Strengthening Families – Enhancing Education Opportunities

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    In Germany, education opportunities are unequally distributed and often determined by family background. Inadequate education is “inherited” more than in other countries. In school and other education institutions, youth from socially disadvantaged and underprivileged familial backgrounds are being left behind. The significant cost society has accumulated from inadequate education effects society as a whole as well as each individual

    Höhere Geburtenraten in Deutschland: die Rolle des Systems frühkindlicher Bildung und Betreuung

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    One of the main future tasks of our society is to slow down demographic change. Therefore, an important aim of German policy is to implement a fertility-friendly family policy. This paper studies the role of early childhood education and care within such a family policy. At first, fertility behaviour in Germany is shortly described. In the next section, the economic theory of fertility is used in order to analyze the individual decision-making process on whether or not to start a family. It turns out that the compatibility of family and job is increasingly significant. As a consequence, a proper system of early child education and care of good quality can be expected to have a positive effect on fertility behaviour. However, in comparison to other European countries Germany is still running a system of only moderate quality. This is why only a fundamental reform of the system of early child education and care can have a significant positive impact on fertility behaviour. In the last section of the paper, we give a preliminary discussion of the main aspects of such a reform. --

    Observation of coasting beam at the HERA Proton--Ring

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    We present data collected with the HERA-B wire target which prove the existence of coasting beam at the HERA proton storage ring. The coasting beam is inherently produced by the proton machine operation and is not dominated by target effects.Comment: 17 pages (Latex), 12 figures (Enc. Postscript

    Transverse beam tail shaping in HERA-p by means of tune modulation

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    The HERA-B experiment utilizes an internal wire target in the halo of the stored proton beam in order to study CP violation. As operational experience shows, interaction rates tend to be extremely sensitive to tiny orbit jitter amplitudes. In order to stabilize these interaction rates, various methods have been studied to increase diffusion in the transverse proton beam tails without affecting the luminosity at the electron-proton collider experiments ZEUS and H1. Tune modulation was found to be a promising method for this task. The present status of these experiments willbe reported
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