422 research outputs found
Strategic Time-Based Metering that Assures Separation for Integrated Operations in a Terminal Airspace
This paper reports an algorithm for strategic time-based metering of air traffic arriving and departing from a large ( tens of nautical miles) area (called here, the commitment region) around an airport or metroplex. The algorithm assures separation continuously in time and avoids a dictation of intent to an aircraft crew. This is accomplished by allowing an aircraft (specifically, its Flight Management System) to specify, and commit to, an intended route and ground speed profile along that route within the commitment region, and by supplying the time at which to enter the region to the aircraft crew. The airspace that comprises the commitment region need not be confined to the terminal airspace and can include some of the enroute space: the size and shape of the commitment region are parameters in the algorithm. An exact formula for including speed profile uncertainty in the algorithm is provided. The algorithm is applied to a number of data sets recorded during actual air traffic operations in the Southern California TRACON in July of 2014 and the Atlanta TRACON in November and December of 2013. The results of the numerical simulations indicate that the algorithm succeeds at keeping the aircraft separated, but introduces, in its current implementation, more separation than that observed in actual operations. This excess separation can be reduced by modeling more accurately the Visual Flight Rules separation practices, a direction for future research
Gold fragmentation induced by stopped antiprotons
A natural gold target was irradiated with the antiproton beam from the Low
Energy Antiproton Ring at CERN. Antiprotons of 200 MeV/c momentum were stopped
in a thick target, products of their annihilations on Au nuclei were detected
using the off-line gamma-ray spectroscopy method. In total, yields for 114
residual nuclei were determined, providing a data set to deduce the complete
mass and charge distribution of all products with A > 20 from a fitting
procedure. The contribution of evaporation and fission decay modes to the total
reaction cross section as well as the mean mass loss were estimated. The
fission probability for Au absorbing antiprotons at rest was determined to be
equal to (3.8+-0.5)%, in good agreement with an estimation derived using other
techniques. The mass-charge yield distribution was compared with the results
obtained for proton and pion induced gold fragmentation. On the average, the
energy released in pbar annihilation is similar to that introduced by ~ 1 GeV
protons. However, compared to proton bombardment products, the yield
distribution of antiproton absorption residues in the N-Z plane is clearly
distinct. The data for antiprotons exhibit also a substantial influence of
odd-even and shell effects.Comment: 14 pages, 9 figures, Revtex 4, to be published in Physical Review
Collisional properties of ultracold K-Rb mixtures
We determine the inter-species s-wave triplet scattering length a3 for all
K-Rb isotopic mixtures by measuring the cross-section for collisions between
41K and 87Rb in different temperature regimes. The positive value
a3=+163(+57,-12)a0 ensures the stability of binary 41K-87Rb Bose-Einstein
condensates. For the fermion-boson mixture 40K-87Rb we obtain a large and
negative scattering length which implies an efficient sympathetic cooling of
the fermionic species down to the degenerate regime.Comment: 4 pages, 4 figures; revised version (references added and small
changes
Composition of the nuclear periphery from antiproton absorption
Thirteen targets with mass numbers from 58 to 238 were irradiated with the
antiproton beam from the Low Energy Antiproton Ring facility at CERN leading to
the formation of antiprotonic atoms of these heavy elements. The antiproton
capture at the end of an atomic cascade results in the production of more or
less excited residual nuclei. The targets were selected with the criterion that
both reaction products with one nucleon less than the proton and neutron number
of the target be radioactive. The yield of these radioactive products after
stopped-antiproton annihilation was determined using gamma-ray spectroscopy
techniques. This yield is related to the proton and neutron density in the
target nucleus at a radial distance corresponding to the antiproton
annihilation site. The experimental data clearly indicate the existence of a
neutron-rich nuclear periphery, a "neutron halo", strongly correlated with the
target neutron separation energy Bn and observed for targets with Bn < 10 MeV.
For two-target nuclei 106Cd and 144Sm, with larger neutron binding energies, a
proton-rich nuclear periphery was observed. Most of the experimental data are
in reasonable agreement with calculations based on current antiproton-nucleus
and pion-nucleus interaction potentials and on nuclear densities deduced with
the help of the Hartree-Fock-Bogoliubov approach. This approach was, however,
unable to account for the 106Cd and 144Sm results.Comment: Latex (RevTeX,aps style), 13 pages + 12 Postscript figure
Атеросклероз: патогенетические механизмы и принципы лечения
Проведен анализ факторов риска развития атеросклероза, дана оценка ряда теорий, объясняющих появление атеросклеротических изменений коронарных артерий. Подчеркивается роль эндотелиальной дисфункции в прогрессировании и обострении сердечно−сосудистых заболеваний. Проанализированы современные подходы к лечению атеросклероза.Risk factors of atherosclerosis development are described, a number of theories explaining atherosclerotic changes appearance in the coronary arteries are analyzed critically. The role of endothelial dysfunction in progress and exacerbation of cardiovascular diseases is emphasized. Contemporary approaches to atherosclerosis treatment are discussed
Virtual reality rehabilitation in patients with chronic obstructive pulmonary disease: A randomized controlled trial
Purpose: This study compared the effects of inpatient-based rehabilitation program of patients with chronic obstructive pulmonary disease (COPD) using non-immersive virtual reality (VR) training with a traditional pulmonary rehabilitation program. The aims of this study were to determine 1) whether rehabilitation featuring both VR as well as exercise training provides benefits over exercise training (ET) alone and 2) whether rehabilitation featuring VR training instead of exercise training provides equivalent benefits. Patients and Methods: The study recruited 106 patients with COPD to a 2-week high-intensity, five times a week intervention. Randomized into three groups, 34 patients participated in a traditional pulmonary rehabilitation program including endurance exercise training (ET), 38 patients participated in traditional pulmonary rehabilitation, including both endurance exercise training and virtual reality training (ET+VR) and 34 patients participated in pulmonary rehabilitation program including virtual reality training but no endurance exercise training (VR). The traditional pulmonary rehabilitation program consisted of fitness exercises, resistance respiratory muscle and relaxation training. Xbox 360® and Kinect® Adventures software were used for the VR training of lower and upper body strength, endurance, trunk control and dynamic balance. Comparison of the changes in the Senior Fitness Test was the primary outcome. Analysis was performed using linear mixed-effects models. Results: The comparison between ET and ET+VR groups showed that ET+VR group was superior to ET group in Arm Curl (p<0.003), Chair stand (p<0.008), Back scratch (p<0.002), Chair sit and reach (p<0.001), Up and go (p<0.000), 6-min walk test (p<0.011). Whereas, the comparison between ET and VR groups showed that VR group was superior to ET group in Arm Curl (p<0.000), Chair stand (p<0.001), 6-min walk test (p<0.031). Conclusion: Results suggest that pulmonary rehabilitation program supplemented with VR training is beneficial intervention to improve physical fitness in patients with COPD
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