6,253 research outputs found
Optimization of thrust algorithm calibration for Computing System (TCS) for Thrust the NASA Highly Maneuverable Aircraft Technology (HiMAT) vehicle's propulsion system
A simplified gross thrust computing technique for the HiMAT J85-GE-21 engine using altitude facility data was evaluated. The results over the full engine envelope for both the standard engine mode and the open nozzle engine mode are presented. Results using afterburner casing static pressure taps are compared to those using liner static pressure taps. It is found that the technique is very accurate for both the standard and open nozzle engine modes. The difference in the algorithm accuracy for a calibration based on data from one test condition was small compared to a calibration based on data from all of the test conditions
Physical activity education in the undergraduate curricula of all UK medical schools: are tomorrow's doctors equipped to follow clinical guidelines?
Physical activity (PA) is a cornerstone of disease prevention and treatment. There is, however, a considerable disparity between public health policy, clinical guidelines and the delivery of physical activity promotion within the National Health Service in the UK. If this is to be addressed in the battle against non-communicable diseases, it is vital that tomorrow's doctors understand the basic science and health benefits of physical activity. The aim of this study was to assess the provision of physical activity teaching content in the curricula of all medical schools in the UK. Our results, with responses from all UK medical schools, uncovered some alarming findings, showing that there is widespread omission of basic teaching elements, such as the Chief Medical Officer recommendations and guidance on physical activity. There is an urgent need for physical activity teaching to have dedicated time at medical schools, to equip tomorrow's doctors with the basic knowledge, confidence and skills to promote physical activity and follow numerous clinical guidelines that support physical activity promotion
Post-menopausal women exhibit greater interleukin-6 responses to mental stress than older men
BACKGROUND: Acute stress triggers innate immune responses and elevation in circulating cytokines including interleukin-6 (IL-6). The effect of sex on IL-6 responses remains unclear due to important limitations of previous studies. PURPOSE: The purpose of this study was to examine sex differences in IL-6 responses to mental stress in a healthy, older (post-menopausal) sample accounting for several moderating factors. METHODS: Five hundred six participants (62.9 ± 5.60 years, 55 % male) underwent 10 min of mental stress consisting of mirror tracing and Stroop task. Blood was sampled at baseline, after stress, and 45 and 75 min post-stress, and assayed using a high sensitivity kit. IL-6 reactivity was computed as the mean difference between baseline and 45 min and between baseline and 75 min post-stress. Main effects and interactions were examined using ANCOVA models. RESULTS: There was a main effect of time for the IL-6 response (F 3,1512 = 201.57, p = <.0001) and a sex by time interaction (F 3,1512 = 17.07, p = <.001). In multivariate adjusted analyses, IL-6 reactivity was significantly greater in females at 45 min (M = 0.37 ± 0.04 vs. 0.20 ± 0.03 pg/mL, p = .01) and at 75 min (M = 0.57 ± 0.05 vs. 0.31 ± 0.05 pg/mL, p = .004) post-stress compared to males. Results were independent of age, adiposity, socioeconomic position, depression, smoking and alcohol consumption, physical activity, statin use, testing time, task appraisals, hormone replacement, and baseline IL-6. Other significant predictors of IL-6 reactivity were lower household wealth, afternoon testing, and baseline IL-6. CONCLUSIONS: Healthy, post-menopausal females exhibit substantially greater IL-6 responses to acute stress. Inflammatory responses if sustained over time may have clinical implications for the development and maintenance of inflammatory-related conditions prevalent in older women
Critical and off-critical studies of the Baxter-Wu model with general toroidal boundary conditions
The operator content of the Baxter-Wu model with general toroidal boundary
conditions is calculated analytically and numerically. These calculations were
done by relating the partition function of the model with the generating
function of a site-colouring problem in a hexagonal lattice. Extending the
original Bethe-ansatz solution of the related colouring problem we are able to
calculate the eigenspectra of both models by solving the associated
Bethe-ansatz equations. We have also calculated, by exploring the conformal
invariance at the critical point, the mass ratios of the underlying massive
theory governing the Baxter-Wu model in the vicinity of its critical point.Comment: 32 pages latex, to appear in J. Phys. A: Math. Ge
Path Integral Monte Carlo Approach to the U(1) Lattice Gauge Theory in (2+1) Dimensions
Path Integral Monte Carlo simulations have been performed for U(1) lattice
gauge theory in (2+1) dimensions on anisotropic lattices. We extractthe static
quark potential, the string tension and the low-lying "glueball" spectrum.The
Euclidean string tension and mass gap decrease exponentially at weakcoupling in
excellent agreement with the predictions of Polyakov and G{\" o}pfert and Mack,
but their magnitudes are five times bigger than predicted. Extrapolations are
made to the extreme anisotropic or Hamiltonian limit, and comparisons are made
with previous estimates obtained in the Hamiltonian formulation.Comment: 12 pages, 16 figure
Childhood obesity and device-measured sedentary behaviour: an instrumental variable analysis of 3,864 mother–offspring pairs
Objective:
Intergenerational data on mother–offspring pairs were utilized in an instrumental variable analysis to examine the longitudinal association between BMI and sedentary behavior.
Methods:
The sample included 3,864 mother–offspring pairs from the 1970 British Cohort Study. Height and weight were recorded in mothers (age 31 [5.4] years) and offspring (age 10 years) and repeated in offspring during adulthood. Offspring provided objective data on sedentary behavior (7‐day thigh‐worn activPAL) in adulthood at age 46 to 47 years.
Results:
Maternal BMI, the instrumental variable, was associated with offspring BMI at age 10 (change per kg/m2, β = 0.11; 95% CI: 0.09 to 0.12), satisfying a key assumption of instrumental variable analyses. Offspring (change per kg/m2, β = 0.010; 95% CI: −0.02 to 0.03 h/d) and maternal BMI (β = 0.017; 95% CI: 0.001 to 0.03 h/d) was related to offspring sedentary time, suggestive of a causal impact of BMI on sedentary behavior (two‐stage least squares analysis, β = 0.18 [SE 0.08], P = 0.015). For moderate‐vigorous physical activity, there were associations with offspring BMI (β = −0.010; 95% CI: −0.017 to −0.004) and maternal BMI (β = −0.007; 95% CI: −0.010 to −0.003), with evidence for causality (two‐stage least squares analysis, β = −0.060 [SE 0.02], P = 0.001).
Conclusions:
There is strong evidence for a causal pathway linking childhood obesity to greater sedentary behavior
An Application of Feynman-Kleinert Approximants to the Massive Schwinger Model on a Lattice
A trial application of the method of Feynman-Kleinert approximants is made to
perturbation series arising in connection with the lattice Schwinger model. In
extrapolating the lattice strong-coupling series to the weak-coupling continuum
limit, the approximants do not converge well. In interpolating between the
continuum perturbation series at large fermion mass and small fermion mass,
however, the approximants do give good results. In the course of the
calculations, we picked up and rectified an error in an earlier derivation of
the continuum series coefficients.Comment: 16 pages, 4 figures, 5 table
Mean Field Renormalization Group for the Boundary Magnetization of Strip Clusters
We analyze in some detail a recently proposed transfer matrix mean field
approximation which yields the exact critical point for several two dimensional
nearest neighbor Ising models. For the square lattice model we show explicitly
that this approximation yields not only the exact critical point, but also the
exact boundary magnetization of a semi--infinite Ising model, independent of
the size of the strips used. Then we develop a new mean field renormalization
group strategy based on this approximation and make connections with finite
size scaling. Applying our strategy to the quadratic Ising and three--state
Potts models we obtain results for the critical exponents which are in
excellent agreement with the exact ones. In this way we also clarify some
advantages and limitations of the mean field renormalization group approach.Comment: 16 pages (plain TeX) + 8 figures (PostScript, appended),
POLFIS-TH.XX/9
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