4,590 research outputs found

    Clinical significance of perioperative Q-wave myocardial infarction: The Emory Angioplasty versus Surgery Trial

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    AbstractObjective: The primary end point of the Emory Angioplasty versus Surgery Trial was a composite of three events: death, Q-wave infarction, and a new large defect on 3-year postoperative thallium scan. This study examines the clinical significance of Q-wave infarction in the surgical cohort (194 patients) of the Emory trial. Methods: Twenty patients (10.3%) with Q-wave infarctions were identified: 13 patients had inferior Q-wave infarctions and seven patients had anterior, lateral, septal, or posterior Q-wave infarctions (termed anterior Q-wave infarctions). Results: In the inferior Q-wave infarction group, postoperative cardiac catheterization (at 1 year or 3 years) in 11 patients revealed normal ejection fraction (ejection fraction >55%) in 10 (91%), no wall motion abnormalities in 10 (91%), and all grafts patent in 10 (91%). In the anterior Q-wave infarction group, postoperative catheterizatiOn in six patients revealed normal ejection fractions in five (83%), no wall motion abnormalities in three (50%), and all grafts patent in three (50%). Average peak postoperative creatine kinase MB levels were as follows: no Q-wave infarction (n = 174) 37 ± 43 IU/L, inferior Q-wave infarction 40 ± 27 IU/L, and anterior Q-wave infarction 58 ± 38 IU/L. Mortality in the 20 patients with Q-wave infarctions was 5% (1/20) at 3 years; in patients without a Q-wave infarction it was 6.3% (11/174) (p = 0.64). Of 17 patients with a Q-wave infarction who underwent postoperative catheterization, 11 (65%) had a normal ejection fraction, normal wall motion, and all grafts patent with an uneventful 3-year postoperative course. Conclusions: The core laboratory screening of postoperative electrocardiograms, particularly in the case of inferior Q-wave infarctions, appears to identify a number of patients as having a Q-wave infarction with minimal clinical significance. Q-wave infarction identified in the postoperative period seems to be a weak end point with little prognostic significance and therefore not valuable for future randomized trials. (J Thorac Cardiovasc Surg 1996;112:1447-54

    Serum vitamin D levels, diabetes and cardio-metabolic risk factors in Aboriginal and Torres Strait Islander Australians

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    Assesses levels of serum 25(OH)D in Aboriginal and Torres Strait Islander Australians and explores relationships between 25(OH)D and cardio-metabolic risk factors and diabetes. Abstract Background: Low levels of serum 25 – hydroxy vitamin D (25(OH)D), have been associated with development of type 2 diabetes and cardiovascular disease (CVD); however there are limited data on serum 25(OH)D in Indigenous Australians, a population at high risk for both diabetes and CVD. We aimed to assess levels of serum 25(OH)D in Aboriginal and Torres Strait Islander Australians and to explore relationships between 25(OH)D and cardio-metabolic risk factors and diabetes. Methods: 592 Aboriginal and/or Torres Strait Islander Australian participants of The eGFR (estimated glomerular filtration rate) Study, a cross-sectional analysis of a cohort study performed in 2007 – 2011, from urban and remote centres within communities, primary care and tertiary hospitals across Northern Territory, Far North Queensland and Western Australia. Assessment of serum 25(OH)D, cardio-metabolic risk factors (central obesity, diabetes, hypertension, history of cardiovascular disease, current smoker, low HDL-cholesterol), and diabetes (by history or HbA1c ≥ 6.5%) was performed. Associations were explored between 25(OH)D and outcome measures of diabetes and number of cardio-metabolic risk factors. Results: The median (IQR) serum 25(OH)D was 60 (45 – 77) nmol/L, 31% had 25(OH)D <50 nmol/L. For participants with 25(OH)D < 50 vs ≥ 50 nmol/L, cardio-metabolic risk profile differed for: diabetes (54%, 36% p < 0.001), past history of cardiovascular disease (16%, 9%, p = 0.014), waist-hip ratio (0.98, 0.92, p < 0.001), urine albumin-creatinine ratio (2.7, 1.5 mg/mmol, p < 0.001). The OR (95% CI) for diabetes was 2.02 (1.03 – 3.95) for people in the lowest vs highest tertiles of 25(OH)D (<53 vs >72 nmol/L, respectively) after adjusting for known cardio-metabolic risk factors. Conclusion: The percentage of 25(OH)D levels <50 nmol/L was high among Aboriginal and Torres Strait Islander Australians from Northern and Central Australia. Low 25(OH)D level was associated with adverse cardio-metabolic risk profile and was independently associated with diabetes. These findings require exploration in longitudinal studies

    Constraints on Finite Soft Supersymmetry-Breaking Terms

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    Requiring the soft supersymmetry-breaking (SSB) parameters in finite gauge-Yukawa unified models to be finite up to and including two-loop order, we derive a two-loop sum rule for the soft scalar-masses. It is shown that this sum rule coincides with that of a certain class of string models in which the massive string states are organized into N=4 supermultiplets. We investigate the SSB sector of two finite SU(5) models. Using the sum rule which allows the non-universality of the SSB terms and requiring that the lightest superparticle particleis neutral, we constrain the parameter space of the SSB sector in each model.Comment: 34 page

    Predicting pollutant removal in constructed wetlands using artificial neural networks (ANNs)

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    Growth in urban population, urbanisation, and economic development has increased the demand for water, especially in water-scarce regions. Therefore, sustainable approaches to water management are needed to cope with the effects of the urbanisation on the water environment. This study aimed to design novel configurations of tidal-flow vertical subsurface flow constructed wetlands (VFCWs) for treating urban stormwater. A series of laboratory experiments were conducted with semi-synthetic influent stormwater to examine the effects of the design and operation variables on the performance of the VFCWs and to identify optimal design and operational strategies, as well as maintenance requirements. The results show that the VFCWs can significantly reduce pollutants in urban stormwater, and that pollutant removal was related to specific VFCW designs. Models based on the artificial neural network (ANN) method were built using inputs derived from data exploratory techniques, such as analysis of variance (ANOVA) and principal component analysis (PCA). It was found that PCA reduced the dimensionality of input variables obtained from different experimental design conditions. The results show a satisfactory generalisation for predicting nitrogen and phosphorus removal with fewer variable inputs, indicating that monitoring costs and time can be reduced

    A formally verified compiler back-end

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    This article describes the development and formal verification (proof of semantic preservation) of a compiler back-end from Cminor (a simple imperative intermediate language) to PowerPC assembly code, using the Coq proof assistant both for programming the compiler and for proving its correctness. Such a verified compiler is useful in the context of formal methods applied to the certification of critical software: the verification of the compiler guarantees that the safety properties proved on the source code hold for the executable compiled code as well

    The 2dF galaxy redshift survey: clustering properties of radio galaxies

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    The clustering properties of local, S1.4 GHz≥ 1 mJy, radio sources are investigated for a sample of 820 objects drawn from the joint use of the Faint Images of the Radio Sky at 20 cm (FIRST) and 2dF Galaxy Redshift surveys. To this aim, we present 271 new bJ≤ 19.45 spectroscopic counterparts of FIRST radio sources to be added to those already introduced in our previous paper. The two-point correlation function for the local radio population is found to be entirely consistent with estimates obtained for the whole sample of 2dFGRS galaxies. From measurements of the redshift-space correlation function ξ(s) we derive a redshift-space clustering length s0 = 10.7+0.8 −0.7 Mpc, while from the projected correlation function Ξ(rT) we estimate the parameters of the real-space correlation function ξ(r) = (r/r0) −γ, r0 = 6.7+0.9 −1.1 Mpc and γ= 1.6 ± 0.1, where h = 0.7 is assumed. Different results are instead obtained if we only consider sources that present signatures of active galactic nucleus (AGN) activity in their spectra. These objects are shown to be very strongly correlated, with r0 = 10.9+1.0 −1.2 Mpc and γ= 2 ± 0.1, a steeper slope than has been claimed in other recent works. No difference is found in the clustering properties of radio-AGNs of different radio luminosity. Comparisons with models for ξ(r) show that AGN-fuelled sources reside in dark matter haloes more massive than ∼1013.4 M⊙, higher than the corresponding figure for radio-quiet quasi-stellar objects. This value can be converted into a minimum black hole mass associated with radio-loud, AGN-fuelled objects of MminBH∼ 109 M⊙. The above results then suggest - at least for relatively faint radio objects - the existence of a threshold black hole mass associated with the onset of significant radio activity such as that of radio-loud AGNs; however, once the activity is triggered, there appears to be no evidence for a connection between black hole mass and level of radio outpu

    The 2dF Galaxy Redshift Survey: correlation functions, peculiar velocities and the matter density of the Universe

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    We present a detailed analysis of the two-point correlation function, ξ(σ, π), from the 2dF Galaxy Redshift Survey (2dFGRS). The large size of the catalogue, which contains ∼220 000 redshifts, allows us to make high-precision measurements of various properties of the galaxy clustering pattern. The effective redshift at which our estimates are made is zs≈ 0.15, and similarly the effective luminosity, Ls≈ 1.4L*. We estimate the redshift-space correlation function, ξ(s), from which we measure the redshift-space clustering length, s0= 6.82 ± 0.28 h−1 Mpc. We also estimate the projected correlation function, Ξ(σ), and the real-space correlation function, ξ(r), which can be fit by a power law (r/r0), with r0= 5.05 ± 0.26 h−1 Mpc, γr= 1.67 ± 0.03. For r≳ 20 h−1 Mpc, ξ drops below a power law as, for instance, is expected in the popular Λ cold dark matter model. The ratio of amplitudes of the real- and redshift-space correlation functions on scales of 8-30 h−1 Mpc gives an estimate of the redshift-space distortion parameter β. The quadrupole moment of ξ(σ, π) on scales 30-40 h−1 Mpc provides another estimate of β. We also estimate the distribution function of pairwise peculiar velocities, ƒ(v), including rigorously the significant effect due to the infall velocities, and we find that the distribution is well fit by an exponential form. The accuracy of our ξ(σ, π) measurement is sufficient to constrain a model, which simultaneously fits the shape and amplitude of ξ(r) and the two redshift-space distortion effects parametrized by β and velocity dispersion, a. We find β= 0.49 ± 0.09 and a= 506 ± 52 km s−1, although the best-fitting values are strongly correlated. We measure the variation of the peculiar velocity dispersion with projected separation, a(σ), and find that the shape is consistent with models and simulations. This is the first time that β and ƒ(v) have been estimated from a self-consistent model of galaxy velocities. Using the constraints on bias from recent estimates, and taking account of redshift evolution, we conclude that β (L=L*, z= 0) = 0.47 ± 0.08, and that the present-day matter density of the Universe, Ωm≈ 0.3, consistent with other 2dFGRS estimates and independent analyse

    The 2dF Galaxy Redshift Survey: the nature of the relative bias between galaxies of different spectral type

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    We present an analysis of the relative bias between early- and late-type galaxies in the Two-degree Field Galaxy Redshift Survey (2dFGRS) - as defined by the η parameter of Madgwick et al., which quantifies the spectral type of galaxies in the survey. We calculate counts in cells for flux-limited samples of early- and late-type galaxies, using approximately cubical cells with sides ranging from 7 to 42 h−1 Mpc. We measure the variance of the counts in cells using the method of Efstathiou et al., which we find requires a correction for a finite volume effect equivalent to the integral constraint bias of the autocorrelation function. Using a maximum-likelihood technique we fit lognormal models to the one-point density distribution, and develop methods of dealing with biases in the recovered variances resulting from this technique. We then examine the joint density distribution function, f(δE, δL), and directly fit deterministic bias models to the joint counts in cells. We measure a linear relative bias of ≈1.3, which does not vary significantly with ℓ. A deterministic linear bias model is, however, a poor approximation to the data, especially on small scales (ℓ≤ 28h−1 Mpc) where deterministic linear bias is excluded at high significance. A power-law bias model with index b1≈ 0.75 is a significantly better fit to the data on all scales, although linear bias becomes consistent with the data for ℓ≳ 40h−1 Mp
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