577 research outputs found

    New Experimental limit on Optical Photon Coupling to Neutral, Scalar Bosons

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    We report on the first results of a sensitive search for scalar coupling of photons to a light neutral boson in the mass range of approximately 1.0 milli-electron volts and coupling strength greater than 10−6^-6 GeV−1^-1 using optical photons. This was a photon regeneration experiment using the "light shining through a wall" technique in which laser light was passed through a strong magnetic field upstream of an optical beam dump; regenerated laser light was then searched for downstream of a second magnetic field region optically shielded from the former. Our results show no evidence for scalar coupling in this region of parameter space.Comment: pdf-file, 10 pages, 4 figures, submitted to Physical Review Letter

    Project 8 Phase III Design Concept

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    We present a working concept for Phase III of the Project 8 experiment, aiming to achieve a neutrino mass sensitivity of 2 eV2~\mathrm{eV} (90 %90~\% C.L.) using a large volume of molecular tritium and a phased antenna array. The detection system is discussed in detail.Comment: 3 pages, 3 figures, Proceedings of Neutrino 2016, XXVII International Conference on Neutrino Physics and Astrophysics, 4-9 July 2016, London, U

    Results from the Project 8 phase-1 cyclotron radiation emission spectroscopy detector

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    The Project 8 collaboration seeks to measure the absolute neutrino mass scale by means of precision spectroscopy of the beta decay of tritium. Our technique, cyclotron radiation emission spectroscopy, measures the frequency of the radiation emitted by electrons produced by decays in an ambient magnetic field. Because the cyclotron frequency is inversely proportional to the electron's Lorentz factor, this is also a measurement of the electron's energy. In order to demonstrate the viability of this technique, we have assembled and successfully operated a prototype system, which uses a rectangular waveguide to collect the cyclotron radiation from internal conversion electrons emitted from a gaseous 83m^{83m}Kr source. Here we present the main design aspects of the first phase prototype, which was operated during parts of 2014 and 2015. We will also discuss the procedures used to analyze these data, along with the features which have been observed and the performance achieved to date.Comment: 3 pages; 2 figures; Proceedings of Neutrino 2016, XXVII International Conference on Neutrino Physics and Astrophysics, 4-9 July 2016, London, U

    Rapidly detecting disorder in rhythmic biological signals: A spectral entropy measure to identify cardiac arrhythmias

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    We consider the use of a running measure of power spectrum disorder to distinguish between the normal sinus rhythm of the heart and two forms of cardiac arrhythmia: atrial fibrillation and atrial flutter. This spectral entropy measure is motivated by characteristic differences in the spectra of beat timings during the three rhythms. We plot patient data derived from ten-beat windows on a "disorder map" and identify rhythm-defining ranges in the level and variance of spectral entropy values. Employing the spectral entropy within an automatic arrhythmia detection algorithm enables the classification of periods of atrial fibrillation from the time series of patients' beats. When the algorithm is set to identify abnormal rhythms within 6 s it agrees with 85.7% of the annotations of professional rhythm assessors; for a response time of 30 s this becomes 89.5%, and with 60 s it is 90.3%. The algorithm provides a rapid way to detect atrial fibrillation, demonstrating usable response times as low as 6 s. Measures of disorder in the frequency domain have practical significance in a range of biological signals: the techniques described in this paper have potential application for the rapid identification of disorder in other rhythmic signals.Comment: 11 page

    Organism-sediment interactions govern post-hypoxia recovery of ecosystem functioning

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    Hypoxia represents one of the major causes of biodiversity and ecosystem functioning loss for coastal waters. Since eutrophication-induced hypoxic events are becoming increasingly frequent and intense, understanding the response of ecosystems to hypoxia is of primary importance to understand and predict the stability of ecosystem functioning. Such ecological stability may greatly depend on the recovery patterns of communities and the return time of the system properties associated to these patterns. Here, we have examined how the reassembly of a benthic community contributed to the recovery of ecosystem functioning following experimentally-induced hypoxia in a tidal flat. We demonstrate that organism-sediment interactions that depend on organism size and relate to mobility traits and sediment reworking capacities are generally more important than recovering species richness to set the return time of the measured sediment processes and properties. Specifically, increasing macrofauna bioturbation potential during community reassembly significantly contributed to the recovery of sediment processes and properties such as denitrification, bedload sediment transport, primary production and deep pore water ammonium concentration. Such bioturbation potential was due to the replacement of the small-sized organisms that recolonised at early stages by large-sized bioturbating organisms, which had a disproportionately stronger influence on sediment. This study suggests that the complete recovery of organism-sediment interactions is a necessary condition for ecosystem functioning recovery, and that such process requires long periods after disturbance due to the slow growth of juveniles into adult stages involved in these interactions. Consequently, repeated episodes of disturbance at intervals smaller than the time needed for the system to fully recover organism-sediment interactions may greatly impair the resilience of ecosystem functioning.

    Using Cognitive Interviewing for the Semantic Enhancement of Multi-Lingual Versions of Personality Questionnaires

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    We discuss the use of cognitive interviewing with bilinguals as an integral part of cross-cultural adaptation of personality questionnaires. The aim is to maximize semantic equivalence to increase the likelihood of items maintaining the intended structure and meaning in the target language. We refer to this part of adaptation as semantic enhancement, and integrate cognitive interviewing within it as a tool for scrutinizing translations, the connotative meaning, and the psychological impact of items across languages. During the adaptation of a work-based personality questionnaire from English to Arabic, Chinese (Mandarin), and Spanish, we cognitively interviewed 12 bilingual participants about 136 items in different languages (17% of all items), of which 67 were changed. A content analysis categorizing the reasons for amending items elicited eleven errors that affect two identified forms of semantic equivalence. We provide the resultant coding scheme as a framework for designing cognitive interviewing protocols and propose a procedure for implementing them. We discuss implications for theory and practic
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