313 research outputs found
Transmural variations of vasodilator-induced changes of myocardial oxygenation vary with age and the presence of diabetes mellitus type II: a study using oxygen-sensitive cardiovascular MR
Molecular Gas in the Lensed Lyman Break Galaxy cB58
We have used the IRAM Plateau de Bure Interferometer to map CO(3-2) emission
from the gravitationally lensed Lyman break galaxy MS1512-cB58. This is the
first detection of a molecular emission line in any Lyman break system; its
integrated intensity implies a total molecular gas mass of 6.6e9 Msun, while
its width implies a dynamical mass of 1.0e10 csc^2i Msun (for a flat Lambda=0.7
cosmology). These estimates are in excellent concordance with nearly all
parameters of the system measured at other wavelengths, and yield a consistent
picture of past and future star formation with no obvious discrepancies
requiring explanation by differential lensing. In particular, we find that the
age and remaining lifetime of the current episode of star formation are likely
to be similar; the surface densities of star formation and molecular gas mass
are related by a Schmidt law; and the fraction of baryonic mass already
converted into stars is sufficient to account for the observed enrichment of
the interstellar medium to 0.4 Zsun. Barring substantial gas inflow or a major
merger, the stars forming in the current episode will have mass and coevality
at z=0 similar to those of a spiral bulge. Assuming cB58 is a typical Lyman
break galaxy apart from its magnification, its global parameters suggest that
the prescriptions for star formation used in some semi-analytic models of
galaxy evolution require moderate revision, although the general prediction
that gas mass fraction should increase with redshift is validated. [abridged]Comment: 41 pages, 6 figures, accepted by Ap
Imaging as an End Point in Ischemia Trials
Imaging of cardiac function and anatomy has advanced at an exponential rate over the past two decades. Our ability to quantitatively assess the degree of myocardial ischemia and accurately define the vascular anatomy using noninvasive techniques is greater than ever before. Current advances is cardiac imaging are allowing us to more safely assess patients for myocardial ischemia and better understand the prognostic implications of our findings. This review summarizes the current state of knowledge in cardiac imaging for the assessment of cardiac ischemia with a focus on the use of cardiac MRI
Re-evaluating the changing geographies of climate activism and the state in the post-climate emergency era in the build-up to COP26
A key aim of much climate activism is to enhance climate ambition and hold local and national governments, as well as global governance forums like the United Nations (UN), to account for the ways in which they implement and monitor climate policy across society to reverse long-term climate change. In recent years new local forms of climate activism, particularly at the urban scale, have taken a more prominent role in this. Although place-based, such local forms of climate activism are at the same time multi-scalar in orientation and strategic focus. This is particularly true in the UK where climate activism has prompted a number of local councils to declare climate emergencies, providing a mechanism by which they can become locally accountable in the delivery of their climate action plans, whilst at the same time holding national government to prior and future commitments to global climate governance. Using interview data with experts working on climate emergency declarations research across the UK, we critically discuss four key themes that have underpinned and catalysed the changing geographies of civil-state relationships within the climate emergency and what this may mean for future global climate governance under the UNFCCC Conferences of the Parties (COP). We argue that decision-makers at COP26 need to take greater heed of the significance of this new broader urban climate activism and its role in geopolitically mobilising more equitable, democratic and inclusive forms of climate governance which give citizens and civil society more credence within global climate policy decision-making processes that have been up to now, dominated by national state discourses
Radial Lattice Quantization of 3D Field Theory
The quantum extension of classical finite elements, referred to as quantum
finite elements ({\bf QFE})~\cite{Brower:2018szu,Brower:2016vsl}, is applied to
the radial quantization of 3d theory on a simplicial lattice for the
manifold. Explicit counter terms to cancel the
one- and two-loop ultraviolet defects are implemented to reach the quantum
continuum theory. Using the Brower-Tamayo~\cite{Brower:1989mt} cluster Monte
Carlo algorithm, numerical results support the QFE ansatz that the critical
conformal field theory (CFT) is reached in the continuum with the full
isometries of restored. The Ricci curvature
term, while technically irrelevant in the quantum theory, is shown to
dramatically improve the convergence opening, the way for high precision Monte
Carlo simulation to determine the CFT data: operator dimensions, trilinear OPE
couplings and the central charge.Comment: 8 pages, 7 figure
Reconstruction of primary vertices at the ATLAS experiment in Run 1 proton–proton collisions at the LHC
This paper presents the method and performance of primary vertex reconstruction in proton–proton collision data recorded by the ATLAS experiment during Run 1 of the LHC. The studies presented focus on data taken during 2012 at a centre-of-mass energy of √s=8 TeV. The performance has been measured as a function of the number of interactions per bunch crossing over a wide range, from one to seventy. The measurement of the position and size of the luminous region and its use as a constraint to improve the primary vertex resolution are discussed. A longitudinal vertex position resolution of about 30μm is achieved for events with high multiplicity of reconstructed tracks. The transverse position resolution is better than 20μm and is dominated by the precision on the size of the luminous region. An analytical model is proposed to describe the primary vertex reconstruction efficiency as a function of the number of interactions per bunch crossing and of the longitudinal size of the luminous region. Agreement between the data and the predictions of this model is better than 3% up to seventy interactions per bunch crossing
Informing UK governance of resilience to climate risks: improving the local evidence-base
International assessments of evidence on climate change (e.g. Intergovernmental Panel on Climate Change, IPCC) or national climate change risk assessments (e.g. UK Climate Change Risk Assessment, CCRA) do not offer a sufficiently granular perspective on climate impacts to adequately inform governance of resilience to climate risks at the local level. Using an analysis of UK decision-makers managing and responding to heatwaves and flood risks, this paper argues how more robust local evidence is needed to inform decision-making regarding adaptation options for enhancing local resilience. We identify evidence gaps and issues relating to local climate change impacts, including sources and quality of evidence used, adequacy and accessibility of evidence available, ill-communicated evidence and conflicting or misused evidence. A lack of appreciation regarding how scientific evidence and personal judgement can mutually enhance the quality of decision-making underpins all of these gaps. Additionally, we find that the majority of evidence currently used is reductively based upon socio-economic and physical characteristics of climate risks. We argue that a step change is needed in local climate resilience that moves beyond current physical and socio-economic risk characterisation to a more inclusive co-constitution of social and politically defined climate risks at the local scale that are better aligned with the local impacts felt and needs of stakeholders
4D strain analysis within non-infarcted myocardium of patients with ischemic cardiomyopathy: potential marker for the prediction of adverse cardiac events
Influence of Sex-Based Differences in Cardiac Phenotype on Atrial Fibrillation Recurrence in Patients Undergoing Pulmonary Vein Isolation
BackgroundPulmonary vein isolation (PVI) is a commonly engaged therapy for symptomatic atrial fibrillation (AF). Prior studies have documented elevated AF recurrence rates among females vs. males. Sex-specific mechanisms underlying this phenomenon are poorly understood. This prospective cohort study aimed to evaluate the sex-based differences in cardiac phenotype and their influence on (AF) recurrence following first-time PVI.MethodsA total of 204 consecutive patients referred for first-time PVI and 101 healthy subjects were prospectively studied by cardiovascular magnetic resonance (CMR) imaging. Multi-chamber volumetric and functional measures were assessed by sex-corrected Z-score analyses vs. healthy subjects. Patients were followed for a median of 2.6 years for the primary outcome of clinical AF recurrence. Multivariable analyses adjusting for age and comorbidities were performed to identify independent predictors of AF recurrence.ResultsAF recurrence following first PVI occurred in 41% of males and 59% of females (p = 0.03). Females were older with higher prevalence of hypertension and thyroid disorders. Z-score-based analyses revealed significantly reduced ventricular volumes, greater left atrial (LA) volumes, and reduced LA contractility in females vs. males. Multivariable analysis revealed each of LA minimum and pre-systolic volumes and booster EF Z-scores to be independently associated with AF recurrence, providing respective hazard ratios of 1.10, 1.19, and 0.89 (p = 0.001, 0.03, and 0.01).ConclusionAmong patients referred for first time PVI, females were older and demonstrated significantly poorer LA contractile health vs. males, the latter independently associated with AF recurrence. Assessment of LA contractile health may therefore be of value to identify female patients at elevated risk of AF recurrence. Factors influencing female patient referral for PVI at more advanced stages of atrial disease warrant focused investigation
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