909 research outputs found
Violation of the Leggett-Garg Inequality in Neutrino Oscillations
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 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
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
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
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
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
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
The status of our investigation of low-energy Xe collisions in the Xenon
bubble chamber DIANA is reported. In the charge-exchange reaction the spectrum of effective mass shows a resonant enhancement
with MeV/c and ^24.4\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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