7,517 research outputs found
Lorentz Violation at One Loop
The proof of one-loop renormalizability of the general Lorentz- and
CPT-violating extension of quantum electrodynamics is described. Application of
the renormalization-group method is discussed and implications for theory and
experiment are considered.Comment: 10 pages, 28 figures, latex, uses sprocl.sty (included), talk
presented at the Second Meeting on CPT and Lorentz Symmetry, Bloomington, IN,
August 200
Chiral Green's Functions in Superconformal Field Theory
By solving the Ward identities in a superconformal field theory we find the
unique three-point Green's functions composed of chiral superfields for N =
1,2,3,4 supersymmetry. We show that the N=1 four-point function with R-charge
equal to one is uniquely determined by the Ward identities up to the
specification of four constants. We discuss why chiral Green's functions above
three-points, with total R-charge greater than N, are not uniquely determined.Comment: 32 pages, no figures, LaTeX2e forma
Prevalence and clinical characteristics of left ventricular dysfunction among elderly patients in general practice setting: cross sectional survey
Objective: To assess the prevalence and clinical characteristics of left ventricular dysfunction among elderly patients in the general practice setting by echocardiographic assessment of ventricular function.
Design: Cross sectional survey.
Setting: Four centre general practice in Poole, Dorset.
Subjects: 817 elderly patients aged 70-84 years.
Main outcomes: Echocardiographic assessment of left ventricular systolic function including measurement of ejection fraction by biplane summation method where possible, clinical symptoms, and signs of left ventricular dysfunction.
Results: The overall prevalence of left ventricular systolic dysfunction was 7.5% (95% confidence interval 5.8% to 9.5%); mild dysfunction (5.0%) was considerably more prevalent than moderate (1.6%) or severe dysfunction (0.7%). Measurement of ejection fraction was possible in 82% of patients (n=667): in patients categorised as having mild, moderate, or severe dysfunction, the mean ejection fraction was 48% (SD 12.0), 38% (8.1), and 26% (7.9) respectively. At all ages the prevalence was much higher in men than in women (odds ratio 5.1, 95% confidence interval 2.6 to 10.1). No clinical symptom or sign was both sensitive and specific. In around half the patients with ventricular dysfunction (52%, 32/61) heart failure had not been previously diagnosed.
Conclusions: Unrecognised left ventricular dysfunction is a common problem in elderly patients in the general practice setting. Appropriate treatment with angiotensin converting enzyme inhibitors has the potential to reduce hospitalisation and mortality in these patients, but diagnosis should not be based on clinical history and examination alone. Screening is feasible in general practice, but it should not be implemented until the optimum method of identifying left ventricular dysfunction is clarified, and the cost effectiveness of screening has been shown
Lift-up, Kelvin-Helmholtz and Orr mechanisms in turbulent jets
Three amplification mechanisms present in turbulent jets, namely lift-up, Kelvin–Helmholtz and Orr, are characterized via global resolvent analysis and spectral proper orthogonal decomposition (SPOD) over a range of Mach numbers. The lift-up mechanism was recently identified in turbulent jets via local analysis by Nogueira et al. (J. Fluid Mech., vol. 873, 2019, pp. 211–237) at low Strouhal number ( St ) and non-zero azimuthal wavenumbers ( m ). In these limits, a global SPOD analysis of data from high-fidelity simulations reveals streamwise vortices and streaks similar to those found in turbulent wall-bounded flows. These structures are in qualitative agreement with the global resolvent analysis, which shows that they are a response to upstream forcing of streamwise vorticity near the nozzle exit. Analysis of mode shapes, component-wise amplitudes and sensitivity analysis distinguishes the three mechanisms and the regions of frequency–wavenumber space where each dominates, finding lift-up to be dominant as St/m→0 . Finally, SPOD and resolvent analyses of localized regions show that the lift-up mechanism is present throughout the jet, with a dominant azimuthal wavenumber inversely proportional to streamwise distance from the nozzle, with streaks of azimuthal wavenumber exceeding five near the nozzle, and wavenumbers one and two most energetic far downstream of the potential core
Sun-induced fluorescence as a proxy for primary productivity across vegetation types and climates
Divergence in Dialogue
Copyright: 2014 Healey et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.This work was supported by the Economic and Social Research Council (ESRC; http://www.esrc.ac.uk/) through the DynDial project (Dynamics of Conversational Dialogue, RES-062-23-0962) and the Engineering and Physical Sciences Research Council (EPSRC; http://www.epsrc.ac.uk/) through the RISER
project (Robust Incremental Semantic Resources for Dialogue, EP/J010383/1). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript
Recent Developments in the Law of the Sea: Synopsis
As part of its annual symposium on the law of the sea, the San Diego Law Review compiles a summary of significant recent developments in the field. This seventh annual synopsis reports major events which occurred between January 1, 1975, and December 31, 1975. Scope, format, and approach are substantially as employed in the past; a minor change is the extended use of footnotes, including citations to newspapers
Measurement of nuclear effects in neutrino interactions with minimal dependence on neutrino energy
We present a phenomenological study of nuclear effects in neutrino
charged-current interactions, using transverse kinematic imbalances in
exclusive measurements. Novel observables with minimal dependence on neutrino
energy are proposed to study quasielastic scattering, and especially resonance
production. They should be able to provide direct constraints on nuclear
effects in neutrino- and antineutrino-nucleus interactions.Comment: 7 pages, 9 figures, accepted version by PR
Determination of the critical stages of processing and tolerance limits for Harmonia axyridis for ‘ladybug taint’ in wine
'Ladybug taint’ (LBT) has recently been reported in some wines from North America, and is associated with 2-isopropyl-3-methoxypyrazine (IPMP), produced by Harmonia axyridis Pallas (the Multicolored Asian Lady Beetle - MALB) when they are incorporated into the winemaking process. It is not known when IPMP is transferred from MALB (e.g. in the vineyard onto grapes or during must processing) nor what minimum MALB densities are required for production of LBT in the final wines. This study sought to clarify these issues through a series of three trials. In the first, MALB were added to 'Riesling' grapes or must at different stages of processing (harvest, crush/destem, pressing or directly to juice), and the resultant wines were analysed chemically and by paired-comparison sensory difference tests.The presence of MALB during processing had minimal effect on the basic composition and spectral properties of the wine. Concentrations of IPMP were < 5 ng·l-1 for all wines except those produced after the direct addition of MALB to the juice (10.3 ng·l-1). Sensorially, control wines (no added MALB) could be differentiated from wines made after MALB were added at crushing/destemming (at 3 beetles per kg grapes), whole bunch pressing and when added directly into the juice, but not when MALB were added and subsequently removed from a simulated harvest treatment or when added during crushing/destemming at 0.3 beetles per kg grapes. In trials 2 and 3, sensory detection thresholds for LBT were determined for white and red wines produced with known densities of MALB. Estimates of ‘tolerance limits’ in the vineyard were then calculated using regression models, and correspond to 1530 and 1260 beetles per t grapes for white and red wines respectively. However, given the range of grape and wine processing options available to producers, many of which are not accounted for in this study, we recommend that a more conservative limit of 200-400 beetles per t grapes may be appropriate. These results should assist in directing appropriate interventions in the vineyard/winery, and provide baseline targets for reducing MALB density to avoid development of LBT.
The impact of the 1783-1784 AD Laki eruption on global aerosol formation processes and cloud condensation nuclei
The 1783–1784 AD Laki flood lava eruption commenced on 8 June 1783 and released 122 Tg of sulphur dioxide gas over the course of 8 months into the upper troposphere and lower stratosphere above Iceland. Previous studies have examined the impact of the Laki eruption on sulphate aerosol and climate using general circulation models. Here, we study the impact on aerosol microphysical processes, including the nucleation of new particles and their growth to cloud condensation nuclei (CCN) using a comprehensive Global Model of Aerosol Processes (GLOMAP). Total particle concentrations in the free troposphere increase by a factor ~16 over large parts of the Northern Hemisphere in the 3 months following the onset of the eruption. Particle concentrations in the boundary layer increase by a factor 2 to 5 in regions as far away as North America, the Middle East and Asia due to long-range transport of nucleated particles. CCN concentrations (at 0.22% supersaturation) increase by a factor 65 in the upper troposphere with maximum changes in 3-month zonal mean concentrations of ~1400 cm<sup>−3</sup> at high northern latitudes. 3-month zonal mean CCN concentrations in the boundary layer at the latitude of the eruption increase by up to a factor 26, and averaged over the Northern Hemisphere, the eruption caused a factor 4 increase in CCN concentrations at low-level cloud altitude. The simulations show that the Laki eruption would have completely dominated as a source of CCN in the pre-industrial atmosphere. The model also suggests an impact of the eruption in the Southern Hemisphere, where CCN concentrations are increased by up to a factor 1.4 at 20&deg; S. Our model simulations suggest that the impact of an equivalent wintertime eruption on upper tropospheric CCN concentrations is only about one-third of that of a summertime eruption. The simulations show that the microphysical processes leading to the growth of particles to CCN sizes are fundamentally different after an eruption when compared to the unperturbed atmosphere, underlining the importance of using a fully coupled microphysics model when studying long-lasting, high-latitude eruptions
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