293 research outputs found
The effects of aerobic and resistance exercise on state anxiety and cognitive function
Background: There is a paucity of data directly comparing the effects of aerobic versus resistance exercise within a single cohort. Objective: The study aimed to investigate the effects of an acute bout of aerobic and resistance exercise on state anxiety and cognitive function. Equipment and methods: Participants completed three laboratory visits randomized between aerobic exercise (cycling at a self-selected intensity), resistance exercise (three sets; 10 repetitions; six exercises), and a control condition (seated rest). State anxiety and cognitive function were assessed before and after each condition. Results: Reductions in state anxiety that approached significance were seen immediately following aerobic exercise yet were non-significant in the resistance and control conditions. Cognitive function significantly improved following aerobic exercise yet this was not evident in the resistance or control conditions. Conclusion: Acute aerobic exercise at a self-selected intensity may be an effective way of reducing state anxiety and improving cognitive function, when compared to seated rest or resistance training
Meson Exchange Currents in (e,e'p) recoil polarization observables
A study of the effects of meson-exchange currents and isobar configurations
in reactions is presented. We use a distorted wave
impulse approximation (DWIA) model where final-state interactions are treated
through a phenomenological optical potential. The model includes relativistic
corrections in the kinematics and in the electromagnetic one- and two-body
currents. The full set of polarized response functions is analyzed, as well as
the transferred polarization asymmetry. Results are presented for proton
knock-out from closed-shell nuclei, for moderate to high momentum transfer.Comment: 44 pages, 18 figures. Added physical arguments explaining the
dominance of OB over MEC, and a summary of differences with previous MEC
calculations. To be published in PR
Channel Coupling in Reactions
The sensitivity of momentum distributions, recoil polarization observables,
and response functions for nucleon knockout by polarized electrons to channel
coupling in final-state interactions is investigated using a model in which
both the distorting and the coupling potentials are constructed by folding
density-dependent effective interactions with nuclear transition densities.
Calculations for O are presented for 200 and 433 MeV ejectile energies,
corresponding to proposed experiments at MAMI and TJNAF, and for C at 70
and 270 MeV, corresponding to experiments at NIKHEF and MIT-Bates. The relative
importance of charge exchange decreases as the ejectile energy increases, but
remains significant for 200 MeV. Both proton and neutron knockout cross
sections for large recoil momenta, MeV/c, are substantially
affected by inelastic couplings even at 433 MeV. Significant effects on the
cross section for neutron knockout are also predicted at smaller recoil
momenta, especially for low energies. Polarization transfer for proton knockout
is insensitive to channel coupling, even for fairly low ejectile energies, but
polarization transfer for neutron knockout retains nonnegligible sensitivity to
channel coupling for energies up to about 200 MeV. The present results suggest
that possible medium modifications of neutron and proton electromagnetic form
factors for can be studied using recoil
polarization with relatively little sensitivity due to final state
interactions.Comment: Substantially revised version accepted by Phys. Rev. C; shortened to
49 pages including 21 figure
Near-field optical power transmission of dipole nano-antennas
Nano-antennas in functional plasmonic applications require high near-field optical power transmission. In this study, a model is developed to compute the near-field optical power transmission in the vicinity of a nano-antenna.
To increase the near-field optical power transmission from a nano-antenna, a tightly focused beam of light is utilized to illuminate a metallic nano-antenna. The modeling and simulation of these structures is performed using 3-D finite element method based full-wave solutions of Maxwell’s equations. Using the optical power transmission model, the interaction of a focused beam of light with plasmonic nanoantennas is investigated. In addition, the tightly focused beam of light is passed through a band-pass filter to identify the effect of various regions of the angular spectrum to the near-field radiation of a dipole nano-antenna. An extensive parametric study is performed to quantify the effects of various parameters on the transmission efficiency of dipole nano-antennas, including length, thickness, width, and the composition of the antenna, as well as the wavelength and half-beam angle of incident light. An optimal dipole nanoantenna geometry is identified based on the parameter studies in this work. In addition, the results of this study show the interaction of the optimized dipole nano-antenna with a magnetic recording medium when it is illuminated with a focused beam of light
Relativistic calculation of nuclear transparency in (e,e'p) reactions
Nuclear transparency in (e,e'p) reactions is evaluated in a fully
relativistic distorted wave impulse approximation model. The relativistic mean
field theory is used for the bound state and the Pauli reduction for the
scattering state, which is calculated from a relativistic optical potential.
Results for selected nuclei are displayed in a Q^2 range between 0.3 and 1.8
(GeV/c)^2 and compared with recent electron scattering data. For Q^2 = 0.3
(GeV/c)^2 the results are lower than data; for higher Q^2 they are in
reasonable agreement with data. The sensitivity of the model to different
prescriptions for the one-body current operator is investigated. The off-shell
ambiguities are rather large for the distorted cross sections and small for the
plane wave cross sections.Comment: 8 pages, 3 figure
Incorporating Fluorine Substitution into Conjugated Polymers for Solar Cells: Three Different Means, Same Results
Fluorinating conjugated polymers is a proven strategy for creating high performance materials in polymer solar cells, yet few studies have investigated the importance of the fluorination method. We compare the performance of three fluorinated systems: a poly(benzodithieno-dithienyltriazole) (PBnDT-XTAZ) random copolymer where 50% of the acceptor units are difluorinated, PBnDT-mFTAZ where every acceptor unit is monofluorinated, and a 1:1 physical blend of the difluorinated and nonfluorinated polymer. All systems have the same degree of fluorination (50%) yet via different methods (chemically vs physically, random vs regular). We show that these three systems have equivalent photovoltaic behavior: ∼5.2% efficiency with a short-circuit current (Jsc) at ∼11 mA cm-2, an open-circuit voltage (Voc) at 0.77 V, and a fill factor (FF) of ∼60%. Further investigation of these three systems demonstrates that the charge generation, charge extraction, and charge transfer state are essentially identical for the three studied systems. Transmission electron microscopy shows no significant differences in the morphologies. All these data illustrate that it is possible to improve performance not only via regular or random fluorination but also by physical addition via a ternary blend. Thus, our results demonstrate the versatility of incorporating fluorine in the active layer of polymer solar cells to enhance device performance. (Graph Presented)
Inclusive electron scattering in a relativistic Green function approach
A relativistic Green function approach to the inclusive quasielastic (e,e')
scattering is presented. The single particle Green function is expanded in
terms of the eigenfunctions of the nonhermitian optical potential. This allows
one to treat final state interactions consistently in the inclusive and in the
exclusive reactions. Numerical results for the response functions and the cross
sections for different target nuclei and in a wide range of kinematics are
presented and discussed in comparison with experimental data.Comment: 12 pages, 7 figures, REVTeX
Relativistic corrections in (gamma,N) knockout reactions
We develop a fully relativistic DWIA model for photonuclear reactions using
the relativistic mean field theory for the bound state and the Pauli reduction
of the scattering state which is calculated from a relativistic optical
potential. Results for the 12C(gamma,p) and 16O(gamma,p) differential cross
sections and photon asymmetries are displayed in a photon energy range between
60 and 257 MeV, and compared with nonrelativistic DWIA calculations. The
effects of the spinor distortion and of the effective momentum approximation
for the scattering state are discussed. The sensitivity of the model to
different prescriptions for the one-body current operator is investigated. The
off-shell ambiguities are large in (gamma,p) calculations, and even larger in
(gamma,n) knockout.Comment: LaTeX2e, 18 pages, and 6 figure
Overall and abdominal obesity and prostate cancer risk in a West African population: An analysis of the Ghana Prostate Study
Obesity has been associated with an increased risk of advanced prostate cancer. However, most studies have been conducted among North American and European populations. Prostate cancer mortality appears elevated in West Africa, yet risk factors for prostate cancer in this region are unknown. We thus examined the relationship between obesity and prostate cancer using a case-control study conducted in Accra, Ghana in 2004 to 2012. Cases and controls were drawn from a population-based sample of 1037 men screened for prostate cancer, yielding 73 cases and 964 controls. An additional 493 incident cases were recruited from the Korle-Bu Teaching Hospital. Anthropometric measurements were taken at enrollment. We used logistic regression to estimate odds ratios (ORs) and 95% confidence intervals (CIs) for associations between body mass index (BMI), waist circumference (WC), waist-hip ratio (WHR) and prostate cancer, adjusting for potential confounders. The mean BMI was 25.1 kg/m2 for cases and 24.3 kg/m2 for controls. After adjustment, men with BMI ≥ 30 kg/m2 had an increased risk of prostate cancer relative to men with BMI < 25 kg/m2 (OR 1.86, 95% CI 1.11-3.13). Elevated WC (OR 1.76, 95% CI 1.24-2.51) and WHR (OR 1.46, 95% CI 0.99-2.16) were also associated with prostate cancer. Associations were not modified by smoking status and were evident for low- and high-grade disease. These findings indicate that overall and abdominal obesity are positively associated with prostate cancer among men in Ghana, implicating obesity as a potentially modifiable risk factor for prostate cancer in this region
Efficacy and safety of cumaru syrup as complementary therapy in mild persistent asthma: a double-blind, randomized, placebo-controlled study
Amburana cearensis is a medicinal plant known as "cumaru". It is used in Northeast Brazil in the treatment of respiratory diseases. This was a randomized, double-blind, placebo-controlled study, with the aim of evaluating the efficacy and safety of cumaru syrup as complementary therapy in mild persistent asthma. The study consisted of 3 phases, pre-treatment, treatment and post-treatment. The primary efficacy outcome was comparison of the changes reported by patients of the cumaru and placebo groups after treatment, using the "Asthma Quality of Life Questionnaire" (AQLQ). The secondary outcome was the effect of cumaru syrup on lung function based on spirometry. The results showed that in the cumaru group, the proportion of patients who had global improvement in asthma symptoms was significantly greater (61.90%, P=0.0009) than in the placebo group (9.52%). Only the spirometric parameters Forced Vital Capacity (FVC) and Forced Expiratory Volume in 1 second (FEV1) showed significant intergroup differences in post-treatment (P0.05). Adverse events were reported by 3 patients (14.29%) in the cumaru group and 3 patients (14.29%) in the placebo group. All adverse events were considered non-serious and mild.Amburana cearensis é uma planta medicinal conhecida como "cumaru". No Nordeste do Brasil é usada no tratamento de doenças respiratórias. Este é um estudo randomizado, duplo-cego e controlado por placebo, com o objetivo de avaliar a eficácia e segurança do xarope de cumaru como terapia complementar da asma persistente leve. O estudo consistiu de três fases, pré-tratamento, tratamento e pós-tratamento. A variável primária para determinação da eficácia foi a comparação das mudanças referidas pelos pacientes dos grupos cumaru e placebo após o tratamento, usando o "Questionário sobre Qualidade de Vida na Asma" (QQVA). A variável secundária foi o efeito do xarope de cumaru na função pulmonar baseado na espirometria. Os resultados mostraram que no grupo cumaru, a proporção de pacientes com melhora global dos sintomas da asma foi significativamente maior (61,90%, P=0.0009) que no grupo placebo (9,52%). Somente os parâmetros espirométricos, capacidade vital forçada (CVF) e volume expiratório forçado no primeiro segundo (VEF1), mostraram diferença intergrupo significtivas no pós-tratamento (P0.05). Eventos adversos foram reportados por 3 pacientes (14,29%) no grupo cumaru e 3 (14,29%) no grupo placebo. Todos os eventos adversos foram não sérios e leves
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