16 research outputs found
Plane-symmetric inhomogeneous magnetized viscous fluid universe with a variable
The behavior of magnetic field in plane symmetric inhomogeneous cosmological
models for bulk viscous distribution is investigated. The coefficient of bulk
viscosity is assumed to be a power function of mass density . The values of cosmological constant for these models are
found to be small and positive which are supported by the results from recent
supernovae Ia observations. Some physical and geometric aspects of the models
are also discussed.Comment: 18 pages, LaTex, no figur
Performance of new criteria for right ventricular hypertrophy and myocardial infarction in patients with pulmonary hypertension due to cor pulmonale and mitral stenosis
Historically, electrocardiographic criteria for right ventricular (RV) hypertrophy has achieved high specificity but low sensitivity. Recently, however, Butler-Leggett et al, have introduced three criteria that attained a 66% sensitivity in a population with RV hypertrophy due to mitral stenosis while maintaining a 95% specificity in an extensive normal control group. Electrocardiographic diagnosis of RV hypertrophy is principally dependent on changes in the QRS complex that may be masked or mimicked by myocardial infarction (MI). This dilemma has been confirmed by documentation of the low specificity of both the Selvester QRS scoring system for MI size estimation (>3 points) and its screening subset (>0 points) in a pure mitral stenosis population. This study introduces the population characterized by RV hypertrophy due to cor pulmonale, which has a mean pulmonary arterial systolic pressure that is higher than the mean for the mitral stenosis population and consequently suggests more severe RV hypertrophy. When compared, the Butler-Leggett criteria for RV hypertrophy are more sensitive in the new population than in the mitral stenosis population (89% versus 60%) and the Selvester QRS scoring system is less specific (12% versus 60%). Three sequential steps are suggested for electrocardiographic analysis: (1) diagnosis of RV hypertrophy using the Butler-Leggett criteria, (2) diagnosis of MI using the Selvester screening criteria in those patients with step 1 negative, and (3) estimation of MI size using the complete Selvester scoring system in patients with step 1 negative and step 2 positive
Chronic obstructive pulmonary disease is an independent predictor of death but not atherosclerotic events in patients with myocardial infarction: analysis of the Valsartan in Acute Myocardial Infarction Trial (VALIANT)
Aims: Chronic obstructive pulmonary disease is an independent predictor of mortality in patients with myocardial infarction (MI). However, the impact on mode of death and risk of atherosclerotic events is unknown.
Methods and results: We assessed the risk of death and major cardiovascular (CV) events associated with chronic obstructive pulmonary disease in 14 703 patients with acute MI enrolled in the Valsartan in Acute Myocardial Infarction (VALIANT) trial. Cox proportional hazards models were used to evaluate the relationship between chronic obstructive pulmonary disease and CV outcomes. A total of 1258 (8.6%) patients had chronic obstructive pulmonary disease. Over a median follow-up period of 24.7 months, all-cause mortality was 30% in patients with chronic obstructive pulmonary disease, compared with 19% in those without. The adjusted hazard ratio (HR) for mortality was 1.14 (95% confidence interval 1.02–1.28). This reflected increased incidence of both non-CV death [HR 1.86 (1.43–2.42)] and sudden death [HR 1.26 (1.03–1.53)]. The unadjusted risk of all pre-specified CV outcomes was increased. However, after multivariate adjustment, chronic obstructive pulmonary disease was not an independent predictor of atherosclerotic events [MI or stroke: HR 0.98 (0.77–1.23)]. Mortality was significantly lower in patients receiving beta-blockers, irrespective of airway disease.
Conclusion: In high-risk patients with acute MI, chronic obstructive pulmonary disease is associated with increased mortality and non-fatal clinical events (both CV and non-CV). However, patients with chronic obstructive pulmonary disease did not experience a higher rate of atherosclerotic events
Preserved lignin structures in early eocene Surat lignites, Cambay Basin, Western India
Lignite samples from Vastan and Tadkeshwar lignite mines, Cambay Basin have been analysed to elucidate lignin precursor using thermochemolysis-gas chromatography-mass spectrometry. The thermochemolysis products of lignites are characterized by monomethoxy-, dimethoxy-, and trimethoxybenzene derivatives originated from -hydroxyphenyl, guaiacyl, and syringyl units of lignin polymer, respectively. The other compounds obtained in thermochemolysates of studied lignites are some resin derived C-15 sesquiterpenoids, with a series of fatty acid methyl esters and -alkanes/alkenes. The methylated guaiacyl and syringyl derivatives originate from the cleavage of beta-O-4 linkages and subsequent methylation of acidic hydroxyl groups of preserved lignin. Gymnosperm lignin is characterized mainly by guaiacyl derivatives whereas angiosperm lignin yields some syringyl-type compounds in addition to guaiacyl-type compounds. By analogy with the lignin structure of modern trees, the abundant occurrences of syringyl derivatives in the thermochemolysis products of Surat lignites clearly demonstrate that the palaeofloral community was dominated by angiosperms during the deposition of these lignites