1,506 research outputs found
Optimum predetection diversity receiving system Patent
Development of optimum pre-detection diversity combining receiving system adapted for use with amplitude modulation, phase modulation, and frequency modulation system
Bone health of middle-aged and older surfers
Purpose: Given the lack of research investigating surfing and bone health, we aimed to assess the bone mineral density (BMD) of middle-aged and older surfers.
Patients and methods: In a cross-sectional observational design, we compared a group of middle-aged and older surfers to a group of non-surfers, age- and sex-matched controls. Participants were males, aged between 50 and 75 years. Volunteers were assessed for body mass index, bone-specific physical activity questionnaire (BPAQ) scores, daily calcium intake, and alcohol intake. Primary outcomes included BMD at the femur and lumbar spine (LS), and T-score, assessed via dual-energy X-ray absorptiometry. Bone biomarkers were also analyzed.
Results: A total of 104 participants (59 surfers and 45 controls) were assessed. Groups were similar with regards to all demographic characteristics except for percentage of lean mass (higher in surfers, mean difference [MD] +2.57%; 95% CI 0.05–5.09; p=0.046) and current BPAQ score (lower in surfers; MD −0.967; 95% CI −0.395 to −1.539; p=0.001). Surfers had a mean surfing experience of 41.2 (SD ±11.8) years and mean surfing exposure of 26.9 (SD ±15.0) hours/month. Controls were divided into two groups, according to their main physical activity: weight-bearing/high intensity (WBHI) and non-weight-bearing/low intensity (NWBLI). When compared to NWBLI controls, surfers had higher LS BMD (MD +0.064; 95% CI 0.002–0.126; p=0.041) and higher T-score (MD +0.40; 95% CI 0.01–0.80; p=0.042); however, surfers had a lower T-score than the WBHI group (MD −0.52; 95% CI −0.02 to −1.0; p=0.039). No other differences were found between groups.
Conclusion: The findings of this study support our hypothesis that regular surfing may be an effective physical activity for middle-aged and older men to decrease bone deterioration related to aging, as we identified positive results for surfers in relation to primary outcomes.Full Tex
Suppression of two-bounce windows in kink-antikink collisions
We consider a class of topological defects in -dimensions with a
deformed kink structure whose stability analysis leads to a
Schr\"odinger-like equation with a zero-mode and at least one vibrational
(shape) mode. We are interested in the dynamics of kink-antikink collisions,
focusing on the structure of two-bounce windows. For small deformation and for
one or two vibrational modes, the observed two-bounce windows are explained by
the standard mechanism of a resonant effect between the first vibrational and
the translational modes. With the increasing of the deformation, the effect of
the appearance of more than one vibrational mode is the gradual disappearance
of the initial two-bounce windows. The total suppression of two-bounce windows
even with the presence of a vibrational mode offers a counterexample from what
expected from the standard mechanism. For even larger deformation, some
two-bounce windows reappear, but with a non-standard structure.Comment: 13 pages, 6 figure
Dual energy X-ray absorptiometry positioning protocols in assessing body composition: A systematic review of the literature:A systematic review of the literature
OBJECTIVES: To systematically identify and assess methods and protocols used to reduce technical and biological errors in published studies that have investigated reliability of dual energy X-ray absorptiometry (DXA) for assessing body composition. DESIGN: Systematic review. METHODS: Systematic searches of five databases were used to identify studies of DXA reliability. Two independent reviewers used a modified critical appraisal tool to assess their methodological quality. Data was extracted and synthesised using a level of evidence approach. Further analysis was then undertaken of methods used to decrease DXA errors (technical and biological) and so enhance DXA reliability. RESULTS: Twelve studies met eligibility criteria. Four of the articles were deemed high quality. Quality articles considered biological and technical errors when preparing participants for DXA scanning. The Nana positioning protocol was assessed to have a strong level of evidence. The studies providing this evidence indicated very high test–retest reliability (ICC 0.90–1.00 or less than 1% change in mean) of the Nana positioning protocol. The National Health and Nutrition Examination Survey (NHANES) positioning protocol was deemed to have a moderate level of evidence due to lack of high quality studies. However, the available studies found the NHANES positioning protocol had very high test–retest reliability. Evidence is limited and reported reliability has varied in papers where no specific positioning protocol was used or reported. CONCLUSIONS: Due to the strong level of evidence of excellent test–retest reliability that supports use of the Nana positioning protocol, it is recommended as the first choice for clinicians when using DXA to assess body composition
Food-bridging: a new network construction to unveil the principles of cooking
In this manuscript we propose, analyse, and discuss a possible new principle
behind traditional cuisine: the Food-bridging hypothesis and its comparison
with the food-pairing hypothesis using the same dataset and graphical models
employed in the food-pairing study by Ahn et al. [Scientific Reports, 1:196
(2011)].
The Food-bridging hypothesis assumes that if two ingredients do not share a
strong molecular or empirical affinity, they may become affine through a chain
of pairwise affinities. That is, in a graphical model as employed by Ahn et
al., a chain represents a path that joints the two ingredients, the shortest
path represents the strongest pairwise chain of affinities between the two
ingredients.
Food-pairing and Food-bridging are different hypotheses that may describe
possible mechanisms behind the recipes of traditional cuisines. Food-pairing
intensifies flavour by mixing ingredients in a recipe with similar chemical
compounds, and food-bridging smoothes contrast between ingredients. Both
food-pairing and food-bridging are observed in traditional cuisines, as shown
in this work.
We observed four classes of cuisines according to food-pairing and
food-bridging: (1) East Asian cuisines, at one extreme, tend to avoid
food-pairing as well as food-bridging; and (4) Latin American cuisines, at the
other extreme, follow both principles. For the two middle classes: (2)
Southeastern Asian cuisines, avoid food-pairing and follow food-bridging; and
(3) Western cuisines, follow food-pairing and avoid food-bridging
Dynamical large deviations for a boundary driven stochastic lattice gas model with many conserved quantities
We prove the dynamical large deviations for a particle system in which
particles may have different velocities. We assume that we have two infinite
reservoirs of particles at the boundary: this is the so-called boundary driven
process. The dynamics we considered consists of a weakly asymmetric simple
exclusion process with collision among particles having different velocities
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