659 research outputs found
URAT: astrometric requirements and design history
The U.S. Naval Observatory Robotic Astrometric Telescope (URAT) project aims
at a highly accurate (5 mas), ground-based, all-sky survey. Requirements are
presented for the optics and telescope for this 0.85 m aperture, 4.5 degree
diameter field-of-view, specialized instrument, which are close to the
capability of the industry. The history of the design process is presented as
well as astrometric performance evaluations of the toleranced, optical design,
with expected wavefront errors included.Comment: 12 pages, 7 figures, SPIE 2006 Orlando conf. proc. Vol. 626
A 5 km resolution regional climate simulation for Central Europe: Performance in high mountain areas and seasonal, regional and elevation-dependent variations
Mountain regions with complex orography are a particular challenge for regional climate simulations. High spatial resolution is required to account for the high spatial variability in meteorological conditions. This study presents a very high-resolution regional climate simulation (5 km) using the Weather Research and Forecasting Model (WRF) for the central part of Europe including the Alps. Global boundaries are dynamically downscaled for the historical period 1980–2009 (ERA-Interim and MPI-ESM), and for the near future period 2020–2049 (MPI-ESM, scenario RCP4.5). Model results are compared to gridded observation datasets and to data from a dense meteorological station network in the Berchtesgaden Alps (Germany). Averaged for the Alps, the mean bias in temperature is about −0.3 °C, whereas precipitation is overestimated by +14% to +19%. R values for hourly, daily and monthly temperature range between 0.71 and 0.99. Temporal precipitation dynamics are well reproduced at daily and monthly scales (R between 0.36 and 0.85), but are not well captured at hourly scale. The spatial patterns, seasonal distributions, and elevation-dependencies of the climate change signals are investigated. Mean warming in Central Europe exhibits a temperature increase between 0.44 °C and 1.59 °C and is strongest in winter and spring. An elevation-dependent warming is found for different specific regions and seasons, but is absent in others. Annual precipitation changes between −4% and +25% in Central Europe. The change signals for humidity, wind speed, and incoming short-wave radiation are small, but they show distinct spatial and elevation-dependent patterns. On large-scale spatial and temporal averages, the presented 5 km RCM setup has in general similar biases as EURO-CORDEX simulations, but it shows very good model performance at the regional and local scale for daily meteorology, and, apart from wind-speed and precipitation, even for hourly values
Co- and multimorbidity patterns in primary care based on episodes of care: results from the German CONTENT project
Contains fulltext :
69171.pdf (publisher's version ) (Open Access)BACKGROUND: Due to technological progress and improvements in medical care and health policy the average age of patients in primary care is continuously growing. In equal measure, an increasing proportion of mostly elderly primary care patients presents with multiple coexisting medical conditions. To properly assess the current situation of co- and multimorbidity, valid scientific data based on an appropriate data structure are indispensable. CONTENT (CONTinuous morbidity registration Epidemiologic NeTwork) is an ambitious project in Germany to establish a system for adequate record keeping and analysis in primary care based on episodes of care. An episode is defined as health problem from its first presentation by a patient to a doctor until the completion of the last encounter for it. The study aims to describe co- and multimorbidity as well as health care utilization based on episodes of care for the study population of the first participating general practices. METHODS: The analyses were based on a total of 39,699 patients in a yearly contact group (YCG) out of 17 general practices in Germany for which data entry based on episodes of care using the International Classification of Primary Care (ICPC) was performed between 1.1.2006 and 31.12.2006. In order to model the relationship between the explanatory variables (age, gender, number of chronic conditions) and the response variables of interest (number of different prescriptions, number of referrals, number of encounters) that were applied to measure health care utilization, we used multiple linear regression. RESULTS: In comparison to gender, patients' age had a manifestly stronger impact on the number of different prescriptions, the number of referrals and number of encounters. In comparison to age (beta = 0.043, p < 0.0001), multimorbidity measured by the number of patients' chronic conditions (beta = 0.51, p < 0.0001) had a manifestly stronger impact the number of encounters for the observation period. Moreover, we could observe that the number of patients' chronic conditions had a significant impact on the number of different prescriptions (beta = 0.226, p < 0.0001) as well as on the number of referrals (beta = 0.3, p < 0.0001). CONCLUSION: Documentation in primary care on the basis of episodes of care facilitates an insight to concurrently existing health problems and related medical procedures. Therefore, the resulting data provide a basis to obtain co- and multimorbidity patterns and corresponding health care utilization issues in order to understand the particular complex needs caused by multimorbidity
Electron focusing, mode spectroscopy and mass enhancement in small GaAs/AlGaAs rings
A new electron focusing effect has been discovered in small single and
coupled GaAs/AlGaAs rings. The focusing in the single ring is attributed solely
to internal orbits. The focusing effect allows the ring to be used as a small
mass spectrometer. The focusing causes peaks in the magnetoresistance at low
fields, and the peak positions were used to study the dispersion relation of
the one-dimensional magnetoelectric subbands. The electron effective mass
increases with the applied magnetic field by a factor of , at a magnetic
field of . This is the first time this increase has been measured
directly. General agreement obtains between the experiment and the subband
calculations for straight channels.Comment: 13 pages figures are available by reques
GROND - a 7-channel imager
We describe the construction of GROND, a 7-channel imager, primarily designed
for rapid observations of gamma-ray burst afterglows. It allows simultaneous
imaging in the Sloan g'r'i'z' and near-infrared bands. GROND was
commissioned at the MPI/ESO 2.2m telescope at La Silla (Chile) in April 2007,
and first results of its performance and calibration are presented.Comment: 25 pages, 21 figs, PASP (subm); version with full-resolution figures
at http://www.mpe.mpg.de/~jcg/GROND/grond_pasp.pd
The spin-orbit interaction as a source of new spectral and transport properties in quasi-one-dimensional systems
We present an exact theoretical study of the effect of the spin-orbit (SO)
interaction on the band structure and low temperature transport in long
quasi-one-dimensional electron systems patterned in two-dimensional electron
gases in zero and weak magnetic fields. We reveal the manifestations of the SO
interaction which cannot in principle be observed in higher dimensional
systems.Comment: 5 pages including 5 figures; RevTeX; to appear in Phys.Rev.B (Rapid
Communications
A beam monitor detector based on doped silica and optical fibres
A beam monitor detector prototype based on doped silica fibres coupled to
optical fibres has been designed, constructed and tested, mainly for
accelerators used in medical applications. Scintillation light produced by Ce
and Sb doped silica fibres moving across the beam has been measured, giving
information on beam position, shape and intensity. Mostly based on commercial
components, the detector is easy to install, to operate and no electronic
components are located near the beam. Tests have been performed with a 2 MeV
proton pulsed beam at an average current of 0.8 {\mu}A. The response
characteristics of Sb doped silica fibres have been studied for the first time
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