909 research outputs found

    Violation of the Leggett-Garg Inequality in Neutrino Oscillations

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    The Leggett-Garg inequality, an analogue of Bell's inequality involving correlations of measurements on a system at different times, stands as one of the hallmark tests of quantum mechanics against classical predictions. The phenomenon of neutrino oscillations should adhere to quantum-mechanical predictions and provide an observable violation of the Leggett-Garg inequality. We demonstrate how oscillation phenomena can be used to test for violations of the classical bound by performing measurements on an ensemble of neutrinos at distinct energies, as opposed to a single neutrino at distinct times. A study of the MINOS experiment's data shows a greater than 6σ6{\sigma} violation over a distance of 735 km, representing the longest distance over which either the Leggett-Garg inequality or Bell's inequality has been tested.Comment: Updated to match published version. 6 pages, 2 figure

    A transboundary transport episode of nitrogen dioxide as observed from GOME and its impact in the Alpine region

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    High tropospheric NO<sub>2</sub> amounts are occasionally detected by space-borne spectrometers above cloudy scenes. For monitoring of near-ground air pollution such data are not directly applicable because clouds shield the highly polluted planetary boundary layer (PBL). We present a method based on trajectories which implicitly estimates the additional sub-cloud NO<sub>2</sub> distribution in order to model concentrations at ground stations. The method is applied to a transboundary pollution transport episode which led to high NO<sub>2</sub> vertical tropospheric column densities (VTCs) over middle Europe observed by the Global Ozone Monitoring Experiment (GOME) instrument above clouds on 17 February 2001. The case study shows that pollution originally residing near the ground in central Germany, the Ruhr area and adjacent parts of the Netherlands and Belgium has been advected to higher tropospheric levels by a passing weather front. Combining the above-cloud NO<sub>2</sub> VTCs with trajectory information covering the GOME columns and including their sub-cloud part yields an estimate of the total NO<sub>2</sub> distribution within the tropospheric columns. The highly polluted air masses are then traced by forward trajectories starting from the GOME columns to move further to the Alpine region and their impact there is assessed. Considering ground-based in-situ measurements in the Alpine region, we conclude that for this episode, at least 50% of the NO<sub>2</sub> concentration recorded at the sites can be attributed to transboundary transport during the frontal passage. This study demonstrates the potential of using NO<sub>2</sub> VTCs from GOME detected above clouds when combined with transport modelling

    Interactive open access to climate observations from Germany

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    During recent years, Germany's national meteorological service (Deutscher Wetterdienst, DWD) has significantly expanded the open access to its climate observations. A first step was a simple FTP-site with the possibility for downloading archives with various categories of data, e.g. national and international station-based meteorological data, derived parameters, gridded products and special categories as e.g. phenological data. The data are based on the observing systems of DWD for Germany as well as international activities of DWD. To improve the interactive and user-friendly access to the data, a new portal has been developed. The portal serves a variety of user requirements that result from the broad range of applications of DWD's climate data. Here we provide an overview of the new climate data portal of DWD. It is based on a systematic implementation of OGC-based technologies. It allows easy graphical access to the station data, but also supports access via technical interfaces, esp. Web-Map- and Web-Feature-Services.</p

    Gamma Dor and Gamma Dor - Delta Sct Hybrid Stars In The CoRoT LRa01

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    A systematic search for gamma Dor and gamma Dor - delta Scuti hybrid pulsators was conducted on the CoRoT LRa01 Exo-archive yielding a total of 418 gamma Dor and 274 hybrid candidates. After an automatic jump correction 194 and 167 respectively, show no more obvious jumps and were investigated in more detail. For about 25\% of these candidates classification spectra from the Anglo-Australian Observatory (AAO) are available. The detailed frequency analysis and a check for combination frequencies together with spectroscopic information allowed us to identify I) 34 gamma Dor stars which show very different pulsation spectra where mostly two modes dominate. Furthermore, a search for regularities in their oscillation spectra allowed to derive recurrent period spacings for 5 of these gamma Dor stars. II) 25 clear hybrid pulsators showing frequencies in the gamma Dor and delta Sct domain and are of A-F spectral type.Comment: Proceedings of the 4th HELAS International Conference held in Lanzarote, 201

    Development of a scale to measure stigma related to podoconiosis in Southern Ethiopia

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    Background: Health-related stigma adds to the physical and economic burdens experienced by people suffering from neglected tropical diseases (NTDs). Previous research into the NTD podoconiosis showed significant stigma towards those with the disease, yet no formal instrument exists by which to assess stigma or interventions to reduce stigma. We aimed to develop, pilot and validate scales to measure the extent of stigma towards podoconiosis among patients and in podoconiosis-endemic communities. Methods: Indicators of stigma were drawn from existing qualitative podoconiosis research and a literature review on measuring leprosy stigma. These were then formulated into items for questioning and evaluated through a Delphi process in which irrelevant items were discounted. The final items formed four scales measuring two distinct forms of stigma (felt stigma and enacted stigma) for those with podoconiosis and those without the disease. The scales were formatted as two questionnaires, one for podoconiosis patients and one for unaffected community members. 150 podoconiosis patients and 500 unaffected community members from Wolaita zone, Southern Ethiopia were selected through multistage random sampling to complete the questionnaires which were interview-administered. The scales were evaluated through reliability assessment, content and construct validity analysis of the items, factor analysis and internal consistency analysis. Results: All scales had Cronbach’s alpha over 0.7, indicating good consistency. The content and construct validity of the scales were satisfactory with modest correlation between items. There was significant correlation between the felt and enacted stigma scales among patients (Spearman’s r = 0.892; p < 0.001) and within the community (Spearman’s r = 0.794; p < 0.001). Conclusion: We report the development and testing of the first standardised measures of podoconiosis stigma. Although further research is needed to validate the scales in other contexts, we anticipate they will be useful in situational analysis and in designing, monitoring and evaluating interventions. The scales will enable an evidencebased approach to mitigating stigma which will enable implementation of more effective disease control and help break the cycle of poverty and NTDs

    Real time approach to tunneling in open quantum systems: decoherence and anomalous diffusion

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    Macroscopic quantum tunneling is described using the master equation for the reduced Wigner function of an open quantum system at zero temperature. Our model consists of a particle trapped in a cubic potential interacting with an environment characterized by dissipative and normal and anomalous diffusion coefficients. A representation based on the energy eigenfunctions of the isolated system, i.e. the system uncoupled to the environment, is used to write the reduced Wigner function, and the master equation becomes simpler in that representation. The energy eigenfunctions computed in a WKB approximation incorporate the tunneling effect of the isolated system and the effect of the environment is described by an equation that it is in many ways similar to a Fokker-Planck equation. Decoherence is easily identified from the master equation and we find that when the decoherence time is much shorter than the tunneling time the master equation can be approximated by a Kramers like equation describing thermal activation due to the zero point fluctuations of the quantum environment. The effect of anomalous diffusion can be dealt with perturbatively and its overall effect is to inhibit tunneling.Comment: 25 pages, 1 figur

    Observation of a baryon resonance with positive strangeness in K+ collisions with Xe nuclei

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    The status of our investigation of low-energy K+K^+Xe collisions in the Xenon bubble chamber DIANA is reported. In the charge-exchange reaction K+Xe→K0pXe′K^+Xe \to K^0 p Xe' the spectrum of K0pK^0 p effective mass shows a resonant enhancement with M=1539±2M = 1539 \pm 2 MeV/c2^2 and Γ≤9MeV/c\Gamma \le 9 MeV/c^2.Thestatisticalsignificanceoftheenhancementisnear. The statistical significance of the enhancement is near 4.4\sigma$. The mass and width of the observed resonance are consistent with expectations for the lightest member of the anti-decuplet of exotic pentaquark baryons, as predicted in the framework of the chiral soliton model.Comment: 9 pages, 4 figure
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