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GRIDCC: Real-time workflow system
The Grid is a concept which allows the sharing of resources between distributed communities, allowing each to progress towards potentially different goals. As adoption of the Grid increases so are the activities that people wish to conduct through it. The GRIDCC project is a European Union funded project addressing the issues of integrating instruments into the Grid. This increases the requirement of workflows and Quality of Service upon these workflows as many of these instruments have real-time requirements. In this paper we present the workflow management service within the GRIDCC project which is tasked with optimising the workflows and ensuring that they meet the pre-defined QoS requirements specified upon them
Heating Based Model Analysis for Explosive Emission Intitiation at Metal Cathodes
This contribution presents a model analysis for the initiation of explosive emission; a phenomena that is observed at cathode surfaces under high current densities. Here, localized heating is quantitatively evaluated on ultrashort time scales as a potential mechanism that initiates explosive emission, based on a two-temperature, relaxation time model. Our calculations demonstrate a strong production of nonequilibrium phonons, ultimately leading to localized melting. Temperatures are predicted to reach the cathode melting point over nanosecond times within the first few monolayers of the protrusion. This result is in keeping with the temporal scales observed experimentally for the initiation of explosive emission
Finite temperature dynamics of the Anderson model
The recently introduced local moment approach (LMA) is extended to encompass
single-particle dynamics and transport properties of the Anderson impurity
model at finite-temperature, T. While applicable to arbitrary interaction
strengths, primary emphasis is given to the strongly correlated Kondo regime
(characterized by the T=0 Kondo scale ). In particular the
resultant universal scaling behaviour of the single-particle spectrum
D(\omega; T) \equiv F(\frac{\w}{\omega_{\rm K}}; \frac{T}{\omega_{\rm K}})
within the LMA is obtained in closed form; leading to an analytical description
of the thermal destruction of the Kondo resonance on all energy scales.
Transport properties follow directly from a knowledge of . The -dependence of the resulting resistivity , which is
found to agree rather well with numerical renormalization group calculations,
is shown to be asymptotically exact at high temperatures; to concur well with
the Hamann approximation for the s-d model down to ,
and to cross over smoothly to the Fermi liquid form in the low-temperature limit. The underlying
approach, while naturally approximate, is moreover applicable to a broad range
of quantum impurity and related models
The Luminosity Function of Nearby Galaxy Clusters II: Redshifts and Luminosity Function for Galaxies in the Region of the Centaurus Cluster
We acquired spectra for a random sample of galaxies within a 0.83 square
degree region centered on the core of the Centaurus cluster. Radial velocities
were obtained for 225 galaxies to limiting magnitudes of V < 19.5. Of the
galaxies for which velocities were obtained, we find 35% to be member galaxies.
Of the 78 member galaxies, magnitudes range from 11.8 < V < 18.5 (-21.6 < M_{V}
< -14.9 for H_o = 70 km s^-1 Mpc^-1) with a limiting central surface brightness
of \mu_o < 22.5 mag arcsec^-2. We constructed the cluster galaxy luminosity
function by using these spectroscopic results to calculate the expected
fraction of cluster members in each magnitude bin. The faint-end slope of the
luminosity function using this method is shallower than the one obtained using
a statistical method to correct for background galaxy contamination. We also
use the spectroscopy results to define surface brightness criteria to establish
membership for the full sample. Using these criteria, we find a luminosity
function very similar to the one constructed with the statistical background
correction. For both, we find a faint-end slope alpha ~ -1.4. Adjusting the
surface brightness membership criteria we find that the data are consistent
with a faint-end slope as shallow as -1.22 or as steep as -1.50. We describe in
this paper some of the limitations of using these methods for constructing the
galaxy luminosity function.Comment: 16 pages, 12 figures, accepted by A
Magnetic properties of the Anderson model: a local moment approach
We develop a local moment approach to static properties of the symmetric
Anderson model in the presence of a magnetic field, focussing in particular on
the strong coupling Kondo regime. The approach is innately simple and
physically transparent; but is found to give good agreement, for essentially
all field strengths, with exact results for the Wilson ratio, impurity
magnetization, spin susceptibility and related properties.Comment: 7 pages, 3 postscript figues. Latex 2e using the epl.cls Europhysics
Letters macro packag
Field-dependent dynamics of the Anderson impurity model
Single-particle dynamics of the Anderson impurity model in the presence of a
magnetic field are considered, using a recently developed local moment
approach that encompasses all energy scales, field and interaction strengths.
For strong coupling in particular, the Kondo scaling regime is recovered. Here
the frequency () and field ()
dependence of the resultant universal scaling spectrum is obtained in large
part analytically, and the field-induced destruction of the Kondo resonance
investigated. The scaling spectrum is found to exhibit the slow logarithmic
tails recently shown to dominate the zero-field scaling spectrum. At the
opposite extreme of the Fermi level, it gives asymptotically exact agreement
with results for statics known from the Bethe ansatz. Good agreement is also
found with the frequency and field-dependence of recent numerical
renormalization group calculations. Differential conductance experiments on
quantum dots in the presence of a magnetic field are likewise considered; and
appear to be well accounted for by the theory. Some new exact results for the
problem are also established
Depression and anxiety predict health-related quality of life in chronic obstructive pulmonary disease: systematic review and meta-analysis
Background: The causal association between depression, anxiety, and health-related quality of life (HRQoL) in chronic obstructive pulmonary disease (COPD) is unclear. We therefore conducted a systematic review of prospective cohort studies that measured depression, anxiety, and HRQoL in COPD. Methods: Electronic databases (Medline, Embase, Cumulative Index to Nursing and Allied Health Literature [CINAHL], British Nursing Index and Archive, PsycINFO and Cochrane database) were searched from inception to June 18, 2013. Studies were eligible for inclusion if they: used a nonexperimental prospective cohort design; included patients with a diagnosis of COPD confirmed by spirometry; and used validated measures of depression, anxiety, and HRQoL. Data were extracted and pooled using random effects models. Results: Six studies were included in the systematic review; of these, three were included in the meta-analysis for depression and two were included for the meta-analysis for anxiety. Depression was significantly correlated with HRQoL at 1-year follow-up (pooled r=0.48, 95% confidence interval 0.37–0.57, P<0.001). Anxiety was also significantly correlated with HRQoL at 1-year follow-up (pooled r=0.36, 95% confidence interval 0.23–0.48, P<0.001). Conclusion: Anxiety and depression predict HRQoL in COPD. However, this longitudinal analysis does not show cause and effect relationships between depression and anxiety and future HRQoL. Future studies should identify psychological predictors of poor HRQoL in well designed prospective cohorts with a view to isolating the mediating role played by anxiety disorder and depressio
Accuracy of Vitalograph lung monitor as a screening test for COPD in primary care.
Microspirometry may be useful as the second stage of a screening pathway among patients reporting respiratory symptoms. We assessed sensitivity and specificity of the Vitalograph® lung monitor compared with post-bronchodilator confirmatory spirometry (ndd Easy on-PC) among primary care chronic obstructive pulmonary disease (COPD) patients within the Birmingham COPD cohort. We report a case-control analysis within 71 general practices in the UK. Eligible patients were aged ≥40 years who were either on a clinical COPD register or reported chronic respiratory symptoms on a questionnaire. Participants performed pre- and post-bronchodilator microspirometry, prior to confirmatory spirometry. Out of the 544 participants, COPD was confirmed in 337 according to post-bronchodilator confirmatory spirometry. Pre-bronchodilator, using the LLN as a cut-point, the lung monitor had a sensitivity of 50.5% (95% CI 45.0%, 55.9%) and a specificity of 99.0% (95% CI 96.6%, 99.9%) in our sample. Using a fixed ratio of FEV1/FEV6 < 0.7 to define obstruction in the lung monitor, sensitivity increased (58.8%; 95% CI 53.0, 63.8) while specificity was virtually identical (98.6%; 95% CI 95.8, 99.7). Within our sample, the optimal cut-point for the lung monitor was FEV1/FEV6 < 0.78, with sensitivity of 82.8% (95% CI 78.3%, 86.7%) and specificity of 85.0% (95% CI 79.4%, 89.6%). Test performance of the lung monitor was unaffected by bronchodilation. The lung monitor could be used in primary care without a bronchodilator using a simple ratio of FEV1/FEV6 as part of a screening pathway for COPD among patients reporting respiratory symptoms
Cooling Flows and Metallicity Gradients in Clusters of Galaxies
The X-ray emission by hot gas at the centers of clusters of galaxies is
commonly modeled assuming the existence of steady-state, inhomogeneous cooling
flows. We derive the metallicity profiles of the intracluster medium expected
from such models. The inflowing gas is chemically enriched by type Ia
supernovae and stellar mass loss in the outer parts of the central galaxy,
which may give rise to a substantial metallicity gradient. The amplitude of the
expected metallicity enhancement towards the cluster center is proportional to
the ratio of the central galaxy luminosity to the mass inflow rate. The
metallicity of the hotter phases is expected to be higher than that of the
colder, denser phases. The metallicity profile expected for the Centaurus
cluster is in good agreement with the metallicity gradient recently inferred
from ASCA measurements (Fukazawa et al. 1994). However, current data do not
rule out alternative models where cooling is balanced by some heat source. The
metallicity gradient does not need to be present in all clusters, depending on
the recent merging history of the gas around the central cluster galaxy, and on
the ratio of the stellar mass in the central galaxy to the gas mass in the
cooling flow.Comment: uuencoded postscript, 8 pages of text + 2 figures, accepted by The
Astrophysical Journal (Letters
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