1,212 research outputs found
Cross-Order Integral Relations from Maximal Cuts
We study the ABDK relation using maximal cuts of one- and two-loop integrals
with up to five external legs. We show how to find a special combination of
integrals that allows the relation to exist, and how to reconstruct the terms
with one-loop integrals squared. The reconstruction relies on the observation
that integrals across different loop orders can have support on the same
generalized unitarity cuts and can share global poles. We discuss the
appearance of nonhomologous integration contours in multivariate residues.
Their origin can be understood in simple terms, and their existence enables us
to distinguish contributions from different integrals. Our analysis suggests
that maximal and near-maximal cuts can be used to infer the existence of
integral identities more generally.Comment: 58 pages, 19 figures; v2 references adde
Trimethylplatinum(IV) complexes of dithiocarbamato ligands: an experimental NMR study on the barrier to C-N bond rotation.
The trimethylplatinum(IV) complexes of a number of dithiocarbamato ligands have been prepared. The complexes are dimeric in the solid-state and in solution, with the ligands acting in both a bridging and chelating fashion. Restricted rotation about the ligand C-N bonds in solution leads to the formation of four rotomers. The kinetics of the restricted rotation were measured by a variety of dynamic NMR techniques in the slow and intermediate exchange regimes. Two distinct processes are observed, namely the independent rotation about each C-N bond and correlated rotation about both C-N bonds. The free energies of activation, which are strongly dependent on the nature of the ligand substituents, are in the range 65 – 88 kJ mol-1 at 298 K. The origins of the barrier to rotation and the effects of the N substituents are discussed. The X-ray structures of fac-[PtMe3(Me2NCS2)]2 (2) and fac-[PtMe3(Ph(H)NCS2)]2 , (6) are reported
“Pure” severe aortic stenosis without concomitant valvular heart diseases:echocardiographic and pathophysiological features
Purpose!#!In echocardiography the severity of aortic stenosis (AS) is defined by effective orifice area (EOA), mean pressure gradient (mPG!##!Methods and results!#!Patients (n = 306) with asymptomatic (n = 133) and symptomatic (n = 173) 'pure' severe AS (mean age 78 ± 9.5 years) defined by indexed EOA < 0.6 cm!##!Conclusion!#!In patients with 'pure' AS according to current guidelines the presence of combined LVH, DD and PAH as accepted pathophysiological sequelae of severe AS cannot be confirmed. Probably, the detection of these secondary cardiac alterations might improve the diagnostic algorithm to avoid overestimation of AS severity
On the non-planar beta-deformed N=4 super-Yang-Mills theory
The beta-deformation is one of the two superconformal deformations of the N=4
super-Yang-Mills theory. At the planar level it shares all of its properties
except for supersymmetry, which is broken to the minimal amount. The tree-level
amplitudes of this theory exhibit new features which depart from the commonly
assumed properties of gauge theories with fields in the adjoint representation.
We analyze in detail complete one-loop amplitudes and a nonplanar two-loop
amplitude of this theory and show that, despite having only N=1 supersymmetry,
two-loop amplitudes have a further-improved ultraviolet behavior. This
phenomenon is a counterpart of a similar improvement previously observed in the
double-trace amplitude of the N=4 super-Yang-Mills theory at three and four
loop order and points to the existence of additional structure in both the
deformed and undeformed theories.Comment: 39 pages, 8 figure
Adiposity has differing associations with incident coronary heart disease and mortality in the Scottish population: cross-sectional surveys with follow-up
Objective:
Investigation of the association of excess adiposity with three different outcomes: all-cause mortality, coronary heart disease (CHD) mortality and incident CHD.
Design:
Cross-sectional surveys linked to hospital admissions and death records.
Subjects:
19 329 adults (aged 18–86 years) from a representative sample of the Scottish population.
Measurements:
Gender-stratified Cox proportional hazards models were used to estimate hazard ratios (HRs) for all-cause mortality, CHD mortality and incident CHD. Separate models incorporating the anthropometric measurements body mass index (BMI), waist circumference (WC) or waist–hip ratio (WHR) were created adjusted for age, year of survey, smoking status and alcohol consumption.
Results:
For both genders, BMI-defined obesity (greater than or equal to30 kg m−2) was not associated with either an increased risk of all-cause mortality or CHD mortality. However, there was an increased risk of incident CHD among the obese men (hazard ratio (HR)=1.78; 95% confidence interval=1.37–2.31) and obese women (HR=1.93; 95% confidence interval=1.44–2.59). There was a similar pattern for WC with regard to the three outcomes; for incident CHD, the HR=1.70 (1.35–2.14) for men and 1.71 (1.28–2.29) for women in the highest WC category (men greater than or equal to102 cm, women greater than or equal to88 cm), synonymous with abdominal obesity. For men, the highest category of WHR (greater than or equal to1.0) was associated with an increased risk of all-cause mortality (1.29; 1.04–1.60) and incident CHD (1.55; 1.19–2.01). Among women with a high WHR (greater than or equal to0.85) there was an increased risk of all outcomes: all-cause mortality (1.56; 1.26–1.94), CHD mortality (2.49; 1.36–4.56) and incident CHD (1.76; 1.31–2.38).
Conclusions:
In this study excess adiposity was associated with an increased risk of incident CHD but not necessarily death. One possibility is that modern medical intervention has contributed to improved survival of first CHD events. The future health burden of increased obesity levels may manifest as an increase in the prevalence of individuals living with CHD and its consequences
Patterns in the Occurrence and Duration of Musculoskeletal Pain and Interference with Work among Eldercare Workers-A One-Year Longitudinal Study with Measurements Every Four Weeks
The objective of this study was to examine patterns of musculoskeletal pain episodes over
time. We conducted a one-year follow-up study among 275 eldercare workers with measurements of
musculoskeletal pain (low back pain (LBP) and neck/shoulder pain (NSP)) and pain-related work
interferenc
Echo-driven V-V optimization determines clinical improvement in non responders to cardiac resynchronization treatment
Echocardiography plays an integral role in the detection of mechanical dyssynchrony in patients with congestive heart failure and in predicting beneficial response to cardiac resynchronization treatment. In patients who derive sup-optimal benefit from biventricular pacing, optimization of atrioventricular delay post cardiac resynchronization treatment has been shown to improve cardiac output. Some recent reports suggest that sequential ventricular pacing may further improve cardiac output. The mechanism whereby sequential ventricular pacing improves cardiac output is likely improved inter and possibly intraventricular synchrony, however these speculations have not been confirmed. In this report we describe the beneficial effect of sequential V-V pacing on inter and intraventricular synchrony, cardiac output and mitral regurgitation severity as the mechanisms whereby sequential biventricular pacing improves cardiac output and functional class in 8 patients who had derived no benefit or had deteriorated after CRT. Online tissue Doppler imaging including tissue velocity imaging, tissue synchronization imaging and strain and strain rate imaging were used in addition to conventional pulsed wave and color Doppler during sequential biventricular pacemaker programming
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