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

The response to receiving phenotypic and genetic coronary heart disease risk scores and lifestyle advice – a qualitative study

BACKGROUND: Individuals routinely receive information about their risk of coronary heart disease (CHD) based on traditional risk factors as part of their primary care. We are also able to calculate individual's risk of CHD based on their genetic information and at present genetic testing for common diseases is available to the public. Due to the limitations in previous studies further understanding is needed about the impact of the risk information on individual's well-being and health-behaviour. We aimed to explore the short term response to receiving different forms of CHD risk information and lifestyle advice for risk reduction. METHODS: We conducted fourty-one face-to-face interviews and two focus groups across England with participants from the INFORM trial who received a combination of individualised phenotypic and genotypic CHD risk scores and web-based lifestyle advice. Risk scores were presented in different formats, e.g. absolute 10 year risk was presented as a thermometer and expressed as a percentage, natural frequency and 'heart age'. Interviews and focus groups explored participants' understanding and reaction to the risk scores and attempts to change lifestyle during the intervention. We tape-recorded and transcribed the interviews and focus groups and analysed them using thematic analysis. RESULTS: Three main themes were identified: limitations of risk scores to generate concern about CHD risk; the advantages of the 'heart age' format of risk score presentation in communicating a message of sub-optimal lifestyle; and intentions and attempts to make moderate lifestyle changes which were prompted by the web-based lifestyle advice. CONCLUSIONS: There are a number of limitations to the use of risk scores to communicate a message about the need for a lifestyle change. Of the formats used, the 'heart age', if noticed, appears to convey the most powerful message about how far from optimal risk an individual person is. An interactive, user friendly, goal setting based lifestyle website can act as a trigger to initiate moderate lifestyle changes, regardless of concerns about risk scores.INFORM is funded by European Commission Framework 7 EPIC-CVD Grant agreement no: 279233. NHS Blood and Transplant funded the INTERVAL trial. DNA extraction and genotyping in INTERVAL/INFORM was funded by the UK National Institute of Health Research. The coordinating team for INTERVAL/INFORM at the Cardiovascular Epidemiology Unit of the University of Cambridge was supported by core funding from: UK Medical Research Council (G0800270), British Heart Foundation (SP/09/002), British Heart Foundation Cambridge Cardiovascular Centre of Excellence, and UK National Institute for Health Research Cambridge Biomedical Research Centre

Using White Dish CMB Anisotropy Data to Probe Open and Flat-Lambda CDM Cosmogonies

We use data from the White Dish experiment to set limits on cosmic microwave background radiation anisotropies in open and spatially-flat-Lambda cold dark matter cosmogonies. We account for the White Dish calibration uncertainty, and marginalize over the offset and gradient removed from the data. Our 2-sigma upper limits are larger than those derived previously. These upper limits are consistent with those derived from the $COBE$-DMR data for all models tested.Comment: 17 pages of latex. Uses aasms4.sty. 4 figures included. Submitted to ApJ

Single-particle and collective excitations in a charged Bose gas at finite temperature

The main focus of this work is on the predictions made by the dielectric formalism in regard to the relationship between single-particle and collective excitation spectra in a gas of point-like charged bosons at finite temperature $T$ below the critical region of Bose-Einstein condensation. Illustrative numerical results at weak coupling ($r_s = 1$) are presented within the Random Phase Approximation. We show that within this approach the single-particle spectrum forms a continuum extending from the transverse to the longitudinal plasma mode frequency and leading to a double-peak structure as $T$ increases, whereas the density fluctuation spectrum consists of a single broadening peak. We also discuss the momentum distribution and the superfluidity of the gas.Comment: 15 pages, 5 figure

Human subjective response to steering wheel vibration caused by diesel engine idle

This study investigated the human subjective response to steering wheel vibration of the type caused by a four-cylinder diesel engine idle in passenger cars. Vibrotactile perception was assessed using sinusoidal amplitude-modulated vibratory stimuli of constant energy level (r.m.s. acceleration, 0.41 m/s(2)) having a carrier frequency of 26 Hz (i.e. engine firing frequency) and modulation frequency of 6.5 Hz (half-order engine harmonic). Evaluations of seven levels of modulation depth parameter m (0.0, 0.1, 0.2, 0.4, 0.6, 0.8, and 1.0) were performed in order to define the growth function of human perceived disturbance as a function of amplitude modulation depth. Two semantic descriptors were used (unpleasantness and roughness) and two test methods (the Thurstone paired-comparison method and the Borg CR-10 direct evaluation scale) for a total of four tests. Each test was performed using an independent group of 25 individuals. The results suggest that there is a critical value of modulation depth m = 0.2 below which human subjects do not perceive differences in amplitude modulation and above which the stimulus-response relationship increases monotonically with a power function. The Stevens power exponents suggest that the perceived unpleasantness is non-linearly dependent on modulation depth m with an exponent greater than 1 and that the perceived roughness is dependent with an exponent close to unity

Combined liver-kidney transplantation: Analysis of patients with preformed lymphocytotoxic antibody

In this report, we address combined liver-kidney transplantation, with particular attention to the apparent phenomenon of protection of kidney allografts to antibody mediated destruction by liver allografts. Four patients were found to have positive crossmatch before the liver phase of the combined transplant (pre-OT/KT samples). These positive crossmatches were due entirely to anti-HLA class I antibodies, as demonstrated by their removal by immunoabsorption on pololed platelets. In three of these patients, post-OT/pre-KT samples showed a conversion to a negative crossmatch (in the fourth patient this was not done). A kidney allograft, harveted from the same donor, was then placed into the recipient, and in patients no. 3, 7, and 12, good initial function was noted. In one of these patients was there evidence of hyperacute rejection. Post-OT/KT samples were collected in patients no. 3, 7, and 8, and then analyzed for the reappearance of donor specific lymphocytotoxic antibodies in the posttransplant period (data on patient no. 12 was not available at time of preparation). Lymphocytotoxic antibodies with donor specificity could not be detected in any of the samples during the first week posttransplant. The decrease in %PRA and conversion of a positive to negative crossmatch following liver transplantation was correlated to the HLA specificty of the antibody found in the pretransplant serum and the HLA type of the tranplanted organs. In the two instances where an HLA specificity could be determined by panel analysis, transplantation with donor organs bearing these HLA specificities led to a specific disppearance of these antibodies during the postransplant phase

Head-Group Conformation in Phospholipids: A Phosphorus-31 Nuclear Magnetic Resonance Study of Oriented Monodomain Dipalmitoylphosphatidylcholine Bilayers

Angular-dependent $^{31}P$ NMR spectra of oriented biaxial monodomain DPPG $H_20$ multilayers are employed to study head-group conformation in this phospholipid. The results indicate that the 0-P-0 plane of the phosphate, where the 0’s are the nonesterified oxygens of the phosphodiester, is tilted at $47 \pm 5^{\circ}$ with respect to the bilayer normal. This $PO_4$ orientation could result in the choline moiety being extended parallel to the bilayer plane, and it will explain the breadth of the axially symmetric $^{31}P$ powder spectrum observed for DPPC in excess water. This work is the first direct observation of this conformation for lecithins and it illustrates the utility of high-resolution solid-state NMR in structural studies of disordered systems.Engineering and Applied Science

Coherent Tunneling of Atoms from Bose-condensed Gases at Finite Temperatures

Tunneling of atoms between two trapped Bose-condensed gases at finite temperatures is explored using a many-body linear response tunneling formalism similar to that used in superconductors. To lowest order, the tunneling currents can be expressed quite generally in terms of the single-particle Green's functions of the isolated Bose gases. A coherent first-order tunneling Josephson current between two atomic Bose-condensates is found, in addition to coherent and dissipative contributions from second-order condensate-noncondensate and noncondensate-noncondensate tunneling. Our work is a generalization of Meier and Zwerger, who recently treated tunneling between uniform atomic Bose gases. We apply our formalism to the analysis of an out-coupling experiment induced by light wave fields, using a simple Bogoliubov-Popov quasiparticle approximation for the trapped Bose gas. For tunneling into the vacuum, we recover the results of Japha, Choi, Burnett and Band, who recently pointed out the usefulness of studying the spectrum of out-coupled atoms. In particular, we show that the small tunneling current of noncondensate atoms from a trapped Bose gas has a broad spectrum of energies, with a characteristic structure associated with the Bogoliubov quasiparticle u^2 and v^2 amplitudes.Comment: 26 pages, 5 figures, minor changes, to appear in PR

First Results from SPARO: Evidence for Large-Scale Toroidal Magnetic Fields in the Galactic Center

We have observed the linear polarization of 450 micron continuum emission from the Galactic center, using a new polarimetric detector system that is operated on a 2 m telescope at the South Pole. The resulting polarization map extends ~ 170 pc along the Galactic plane and ~ 30 pc in Galactic latitude, and thus covers a significant fraction of the central molecular zone. Our map shows that this region is permeated by large-scale toroidal magnetic fields. We consider our results together with radio observations that show evidence for poloidal fields in the Galactic center, and with Faraday rotation observations. We compare all of these observations with the predictions of a magnetodynamic model for the Galactic center that was proposed in order to explain the Galactic Center Radio Lobe as a magnetically driven gas outflow. We conclude that the observations are basically consistent with the model.Comment: 11 pages, 2 figures, 1 table, submitted to ApJ Let