Numerical calculations of a high brilliance synchrotron source and on issues with characterizing strong radiation damping effects in non-linear Thomson/Compton backscattering experiments

A number of theoretical calculations have studied the effect of radiation reaction forces on radiation distributions in strong field counter-propagating electron beam-laser interactions, but could these effects - including quantum corrections - be observed in interactions with realistic bunches and focusing fields, as is hoped in a number of soon to be proposed experiments? We present numerical calculations of the angularly resolved radiation spectrum from an electron bunch with parameters similar to those produced in laser wakefield acceleration experiments, interacting with an intense, ultrashort laser pulse. For our parameters, the effects of radiation damping on the angular distribution and energy distribution of \emph{photons} is not easily discernible for a "realistic" moderate emittance electron beam. However, experiments using such a counter-propagating beam-laser geometry should be able to measure such effects using current laser systems through measurement of the \emph{electron beam} properties. In addition, the brilliance of this source is very high, with peak spectral brilliance exceeding $10^{29}$ photons$\,$s$^{-1}$mm$^{-2}$mrad$^{-2}(0.1$% bandwidth$)^{-1}$ with approximately 2% efficiency and with a peak energy of 10 MeV.Comment: 11 figures, 11 page

Thermalization of magnons in yttrium-iron garnet: nonequilibrium functional renormalization group approach

Using a nonequilibrium functional renormalization group (FRG) approach we calculate the time evolution of the momentum distribution of a magnon gas in contact with a thermal phonon bath. As a cutoff for the FRG procedure we use a hybridization parameter {\Lambda} giving rise to an artificial damping of the phonons. Within our truncation of the FRG flow equations the time evolution of the magnon distribution is obtained from a rate equation involving cutoff-dependent nonequilibrium self-energies, which in turn satisfy FRG flow equations depending on cutoff-dependent transition rates. Our approach goes beyond the Born collision approximation and takes the feedback of the magnons on the phonons into account. We use our method to calculate the thermalization of a quasi two-dimensional magnon gas in the magnetic insulator yttrium-iron garnet after a highly excited initial state has been generated by an external microwave field. We obtain good agreement with recent experiments.Comment: 16 pages, 6 figures, final versio

Proton Association Constants of His 37 in the Influenza-A M218–60 Dimer-of-Dimers

National Institute of Biomedical Imaging and Bioengineering (U.S.) (EB001960)National Institute of Biomedical Imaging and Bioengineering (U.S.) (EB002026)National Institute of Biomedical Imaging and Bioengineering (U.S.) (GM094648

Associations between exposure to takeaway food outlets, takeaway food consumption, and body weight in Cambridgeshire, UK: population based, cross sectional study.

OBJECTIVES: To examine the association between environmental exposure to takeaway food outlets, takeaway food consumption, and body weight, while accounting for home, work place, and commuting route environments. DESIGN: Population based, cross sectional study, using data on individual participants' diet and weight, and objective metrics of food environment exposure. PARTICIPANTS: Working adults participating in the Fenland Study, Cambridgeshire, UK (n = 5442, aged 29-62 years), who provided home and work addresses and commuting preferences. Takeaway food outlet exposure was derived using data from local authorities for individual environmental domains (at home, at work, and along commuting routes (the shortest route between home and work)), and for exposure in all three domains combined. Exposure was divided into quarters (Q); Q1 being the least exposed and Q4 being the most exposed. MAIN OUTCOME MEASURES: Self reported consumption of takeaway type food (g/day; pizza, burgers, fried foods, and chips) using food frequency questionnaires, measured body mass index, and cut-offs for body mass index as defined by the World Health Organization. RESULTS: In multiple linear regression models, exposure to takeaway food outlets was positively associated with consumption of takeaway food. Among domains at home, at work, and along commuting routes, associations were strongest in work environments (Q4 v Q1; β coefficient = 5.3 g/day, 95% confidence interval 1.6 to 8.7; P<0.05), with evidence of a dose-response effect. Associations between exposure in all three domains combined and consumption were greater in magnitude across quarters of exposure (Q4 v Q1; 5.7 g/day, 2.6 to 8.8; P<0.001), with evidence of a dose-response effect. Combined exposure was especially strongly associated with increased body mass index (Q4 v Q1; body mass index 1.21, 0.68 to 1.74; P<0.001) and odds of obesity (Q4 v Q1; odds ratio 1.80, 1.28 to 2.53; P<0.05). There was no evidence of effect modification by sex. CONCLUSIONS: Exposure to takeaway food outlets in home, work, and commuting environments combined was associated with marginally higher consumption of takeaway food, greater body mass index, and greater odds of obesity. Government strategies to promote healthier diets through planning restrictions for takeaway food could be most effective if focused around the workplace

Left ventricular function after valve repair for chronic mitral regurgitation: Predictive value of preoperative assessment of contractile reserve by exercise echocardiography

Objectives.We evaluated the value of preoperative assessment of left ventricular contractile reserve in predicting ventricular function after valve repair for minimally symptomatic mitral regurgitation.Background.The optimal timing for operation in minimally symptomatic patients with significant mitral regurgitation is controversial. Accurate preoperative assessment of left ventricular function is difficult, and the ability to predict postoperative function is limited. Previous studies in patients undergoing mitral valve replacement may not be applicable in the present era of valve repair.Methods.We performed exercise echocardiography in 139 patients with isolated mitral regurgitation and no coronary disease, 74 of whom subsequently underwent uncomplicated valve repair. We measured rest left ventricular end-systolic dimension, end-systolic wall stress and positive first derivative of left ventricular pressure (dP/dt). End-diastolic and end-systolic volumes and ejection fraction were measured preoperatively at rest, immediately after exercise and postoperatively.Results.Ejection fraction decreased postoperatively to 55 ± 10% from a rest preoperative value of 64 ± 9% (p < 0.001). Compared with patients with a postoperative ejection fraction ≥50% (n = 56), patients with postoperative ejection fraction <50% (n = 18) had a significantly lower preoperative exercise ejection fraction (57 ± 11% vs. 73 ± 9%, p < 0.0005), a larger exercise end-systolic volume index (32 ± 8 vs. 18 ± 7 cm3/m2, p < 0.0005) and a lower change in ejection fraction with exercise (−4 ± 8% vs. 9 ± 10%, p < 0.005). Preoperative rest indexes, including dP/dt, end-systolic wall stress and end-systolic volume index were less predictive, whereas exercise capacity, rest ejection fraction and end-systolic dimension were not predictive of postrepair ejection fraction. An exercise end-systolic volume index >25 cm3/m2 was the best predictor of postoperative dysfunction, with a sensitivity and specificity of 83%.Conclusions.In minimally symptomatic patients with mitral regurgitation, latent ventricular dysfunction may be indicated by a limited contractile reserve, manifest at exercise as an inadequate increase in ejection fraction and a larger end-systolic volume. These variables may also be used to predict left ventricular function after repair

Scaling Flows and Dissipation in the Dilute Fermi Gas at Unitarity

We describe recent attempts to extract the shear viscosity of the dilute Fermi gas at unitarity from experiments involving scaling flows. A scaling flow is a solution of the hydrodynamic equations that preserves the shape of the density distribution. The scaling flows that have been explored in the laboratory are the transverse expansion from a deformed trap ("elliptic flow"), the expansion from a rotating trap, and collective oscillations. We discuss advantages and disadvantages of the different experiments, and point to improvements of the theoretical analysis that are needed in order to achieve definitive results. A conservative bound based on the current data is that the minimum of the shear viscosity to entropy density ration is that eta/s is less or equal to 0.5 hbar/k_B.Comment: 32 pages, prepared for "BCS-BEC crossoverand the Unitary Fermi Gas", Lecture Notes in Physics, W. Zwerger (editor), Fig. 5 corrected, note added; final version, corrected typo in equ. 9

Suppression of human immunodeficiency virus replication during acute measles.

To determine the effect of measles virus coinfection on plasma human immunodeficiency virus (HIV) RNA levels, a prospective study of hospitalized children with measles was conducted between January 1998 and October 2000 in Lusaka, Zambia. Plasma HIV RNA levels were measured during acute measles and 1 month after hospital discharge. The median plasma HIV RNA level in 33 children with measles who were followed longitudinally was 5339 copies/mL at study entry, 60,121 copies/mL at hospital discharge, and 387,148 copies/mL at 1-month follow-up. The median plasma HIV RNA level in children without acute illness was 228,454 copies/mL. Plasma levels of immune activation markers were elevated during the period of reduced plasma HIV RNA. Plasma levels of several potential HIV suppressive factors also were elevated during acute measles. HIV replication is transiently suppressed during acute measles at a time of intense immune activation