961 research outputs found
A Three-Dimensional Position Architecture Using Digital TDE Receiver and Cylindrical Array Antenna
AbstractThe robust three-dimensional position architecture is proposed in the paper, where the hybrid time difference of arrival (TDOA) and direction of arrival (DOA) position system was designed to backup the four-station TDOA position system. The digital time delay estimation (TDE) receiver is used for TDOA measurement and the cylindrical array antenna is used for DOA measurement. The general formula of linear phase compensation for cylindrical array antenna in horizontal plane is derived. The detection probability of the TDE receiver and the circular error probability (CEP) of the position systems over Rayleigh fading channel were numerically computed in three-dimensional space. Simulations indicate that the position accuracy of the four-station TDOA position system is degraded but the location function can be retained by the hybrid TDOA and DOA position system when any one of four-stations is out of work
Not So Lonely Surfers: Loneliness, Social Support, Internet Use and Life Satisfaction in Older Adults
Older adults often encounter diminished social support, loneliness and lower life satisfaction levels. Many of these struggles stem from a loss of social interaction with social network ties that are important to them. Information and communication technology (ICT) use offers promise in helping them maintain their social ties. In this longitudinal study, participants included 306 older adults in 19 different assisted and independent living communities. Through random assignment at the community level, residents were offered ICT training, interaction with trainees (placebo), and a survey only control condition with no interaction. Residents in each group were surveyed at pretest, posttest, and 3, 6, and 12 months post training. This analysis examines the use of the Internet as a tool for stress buffering to maintain and enrich social ties, reducing the impact of loneliness and improving life satisfaction measures. Significant interactions were found between ICT attitudes and loneliness, social support and life satisfaction.ye
A prospective study of venous thromboembolism in relation to factor V Leiden and related factors
The aim of this study was to examine the occurrence of venous thromboembolism (VTE) in relation to factor V-related risk factors. Using a nested case-control design combining 2 population-based prospective studies, we measured factor V Leiden, HR2 haplotype, activated protein C (APC) resistance, and plasma factor V antigen in 335 participants who developed VTE during 8 years of follow-up and 688 controls. The overall odds ratio (OR) of VTE was 3.67 (95% Cl, 2.20-6.12) in participants carrying factor V Leiden compared with noncarriers. APC resistance measured after predilution with factor V-deficient plasma conferred an OR of 2.58 (95% Cl, 1.62-4.10). All 3 participants homozygous for the HR2 haplotype had a VTE, and the OR of VTE for homozygosity was estimated to be 5.5 (95% Cl, 2.45-12.5). Carriers of the HR2 haplotype otherwise were not at increased risk of VTE overall (OR = 1.05; 95% Cl, 0.64-1.72), but double heterozygotes for HR2 and factor V Leiden carried an OR of idiopathic VTE of 16.3 (95% Cl, 1.7-159) compared with noncarriers. Factor V antigen also was not associated with VTE overall, but for participants with the combination of high factor V antigen plus factor V Leiden the OR of idiopathic VTE was 11.5 (95% Cl, 4.2-31.4). In the general population, APC resistance and factor V Leiden were important VTE risk factors; homozygosity for the HR2 haplotype may be a risk factor but was rare; otherwise, HR2 haplotype and factor V antigen were not risk factors except in carriers of factor V Leiden
Theoretical prediction of CNT-CF/PP composite tensile properties using various numerical modeling methods
Development of effective models to predict tensile properties of ‘carbon nanotube coated carbon fibre reinforced polypropylene (CNT-CF/PP)’ composites is briefly discussed. The composite taken as the reference is based on the highest growth mechanism of CNTs over carbon fibres. Halpin-Tsai and Combined Voigt-Reuss model has been implemented. Young's modulus for CNT-CF/PP composites has been found 4.5368 GPa and the tensile strength has been estimated 45.367 MPa considering the optimum operating condition of chemical vapor deposition (CVD) technique. Stiffness of the composite is represented through the stress-strain plots; stiffness is proportional to the steepness of the slope. There are slight deviations of results that have been found theoretically over the experimental issues
The Discrepancy Between tau and e+e- Spectral Functions Revisited and the Consequences for the Muon Magnetic Anomaly
We revisit the procedure for comparing the pi pi spectral function measured
in tau decays to that obtained in e+e- annihilation. We re-examine the
isospin-breaking corrections using new experimental and theoretical input, and
find improved agreement between the tau- --> pi- pi0 nu_tau branching fraction
measurement and its prediction using the isospin-breaking-corrected e+e- -->
pi+pi- spectral function, though not resolving all discrepancies. We recompute
the lowest order hadronic contributions to the muon g-2 using e+e- and tau data
with the new corrections, and find a reduced difference between the two
evaluations. The new tau-based estimate of the muon magnetic anomaly is found
to be 1.9 standard deviations lower than the direct measurement.Comment: 10 pages, 6 figures, submitted to Eur. Phys. J. C; (v2): Revised
version with improved and uniform treatment of tau and e+e- data with
HVPTools and a few minor bug fixes; (v3): Final version accepted for
publicatio
Comportamento de dois genótipos de milho cultivados em sistema de aléias preestabelecido com diferentes leguminosas arbóreas.
O cultivo em aléias tem sido recomendado como alternativa para a substituição da agricultura de corte e queima, no trópico úmido, devido à grande capacidade de produção de matéria orgânica e de reciclagem de nutrientes, mas algumas dúvidas quanto à sustentabilidade e à competição interespecífica são persistentes. O objetivo no trabalho foi avaliar a viabilidade da cultura do milho em um sistema de cultivo em aléias de leguminosas arbóreas. O delineamento experimental utilizado foi em blocos casualisados, com quatro repetições dos tratamentos: aléias de sombreiro (Clitoria fairchildiana), ingá (Inga edulis), guandu (Cajanus cajan) e leucena (Leucaena leucocephala) e uma testemunha sem aléias. Foram avaliadas a remobilização de carbono e nitrogênio, massa de grãos, massa de mil grãos e competição interespecífica entre as cultivares de milho e as leguminosas. A produção de grãos foi maior nas parcelas com C. fairchildiana e L. leucocephala. A produtividade do híbrido de milho foi superior à da variedade em todos os tratamentos. A produtividade e a massa de mil grãos de milho não são negativamente afetadas pela distância da linha da leguminosa arbórea. Esse estudo conclui que o sistema de aléias com leguminosas arbóreas é uma alternativa importante ao manejo sustentável dos agroecossistemas no tropico úmido. Além disso, nessa região a produtividade em grãos na cultura do milho é favorecida no sistema de aléias preeestabelecidas com as leguminosas arbóreas sombreiro, ingá e leucena e pela utilização de genótipos eficientes no aproveitamento do nitrogênio, cujo sincronismo entre a liberação e a absorção do N aplicado por meio das leguminosas deve ser aprimorado
Pion, kaon, proton and anti-proton transverse momentum distributions from p+p and d+Au collisions at GeV
Identified mid-rapidity particle spectra of , , and
from 200 GeV p+p and d+Au collisions are reported. A
time-of-flight detector based on multi-gap resistive plate chamber technology
is used for particle identification. The particle-species dependence of the
Cronin effect is observed to be significantly smaller than that at lower
energies. The ratio of the nuclear modification factor () between
protons and charged hadrons () in the transverse momentum
range GeV/c is measured to be
(stat)(syst) in minimum-bias collisions and shows little
centrality dependence. The yield ratio of in minimum-bias d+Au
collisions is found to be a factor of 2 lower than that in Au+Au collisions,
indicating that the Cronin effect alone is not enough to account for the
relative baryon enhancement observed in heavy ion collisions at RHIC.Comment: 6 pages, 4 figures, 1 table. We extended the pion spectra from
transverse momentum 1.8 GeV/c to 3. GeV/
Demonstration of the temporal matter-wave Talbot effect for trapped matter waves
We demonstrate the temporal Talbot effect for trapped matter waves using
ultracold atoms in an optical lattice. We investigate the phase evolution of an
array of essentially non-interacting matter waves and observe matter-wave
collapse and revival in the form of a Talbot interference pattern. By using
long expansion times, we image momentum space with sub-recoil resolution,
allowing us to observe fractional Talbot fringes up to 10th order.Comment: 17 pages, 7 figure
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