40 research outputs found
Comparison of treatment outcomes of new smear-positive pulmonary tuberculosis patients by HIV and antiretroviral status in a TB/HIV clinic, Malawi
Background: Smear-positive pulmonary TB is the most infectious form of TB. Previous studies on the effect of HIV and antiretroviral therapy on TB treatment outcomes among these highly infectious patients demonstrated conflicting results, reducing understanding of important issues. Methods: All adult smear-positive pulmonary TB patients diagnosed between 2008 and 2010 in Malawi's largest public, integrated TB/HIV clinic were included in the study to assess treatment outcomes by HIV and antiretroviral therapy status using logistic regression. Results: Of 2,361 new smear-positive pulmonary TB patients, 86% had successful treatment outcome (were cured or completed treatment), 5% died, 6% were lost to follow-up, 1% failed treatment, and 2% transferred-out. Overall HIV prevalence was 56%. After adjusting for gender, age and TB registration year, treatment success was higher among HIV-negative than HIV-positive patients (adjusted odds ratio 1.49; 95% CI: 1.14-1.94). Of 1,275 HIV-infected pulmonary TB patients, 492 (38%) received antiretroviral therapy during the study. Pulmonary TB patients on antiretroviral therapy were more likely to have successful treatment outcomes than those not on ART (adjusted odds ratio: 1.83; 95% CI: 1.29-2.60). Conclusion: HIV co-infection was associated with poor TB treatment outcomes. Despite high HIV prevalence and the integrated TB/HIV setting, only a minority of patients started antiretroviral therapy. Intensified patient education and provider training on the benefits of antiretroviral therapy could increase antiretroviral therapy uptake and improve TB treatment success among these most infectious patients. © 2013 Tweya et al
Sources of acoustic emission during fatigue of Ti-6Al-4V: effect of microstructure
The fundamentals of acoustic emission (AE) analysis of fatigue cracking were applied to Ti-6Al-4V. The effect of microstructure on the characteristics of the AE events generated and the failure mechanisms which produced AE in Ti-6Al-4V were established. Lamellar microstructures generated one to two orders of magnitude more emission than equiaxed microstructures. The combination of larger grain size, more continuous α/ÎČ interfaces, more tortuous crack-front geometry, cleavage and intergranular fracture in lamellar microstructures accounts for the greater amount of emission. For lamellar microstructures, most AE events were generated in the upper 20% of the stress range, whereas in equiaxed microstructures, most events were generated at lower stresses. Most AE events were generated during crack opening and also at low stresses. AE events having high level intensities were also generated at stresses other than the peak stress. This is because in titanium alloys, which have both high strength and toughness, AE events are generated from both plastic zone extension and crack extension.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/44721/1/10853_2004_Article_BF00542927.pd
Dilution of oral D3âCreatine to measure creatine pool size and estimate skeletal muscle mass: development of a correction algorithm
Abstract Background Muscle mass can be measured directly in vivo by isotope dilution, using Creatineâ(methylâd3) monohydrate (D3âCr) by mouth followed by measurement of the steadyâstate enrichment of D3âcreatinine (D3âCrn) in urine. Isotope dilution methods require knowledge of the amount of tracer delivered to the pool of interest. In a subset of human subjects, a small amount of orally administered D3âCr âspillsâ into urine after absorption and prior to transport into skeletal muscle cells. The objectives were to develop a method to correct for spillage to compare the estimate of muscle mass by D3âCr dilution to other assessments of fatâfree mass. Methods Subjects (19 males, 23â81 years old; 20 females, 20â77 years old) ingested a single dose of 60 mg D3âCr and urine was collected prior to and daily for 4 days following the dose. Fasting morning urine samples was assessed for D3âCr, total Cr, D3âCrn, and total Crn concentrations, as well as isotopic enrichments of D3âCrn, by LC/MS. The 24âh urine collections over 3 days after the dose of D3âCr were also performed to determine D3âCr spillage. Total body water, fat mass, and fatâfree mass were assessed by bioelectrical impedance spectroscopy (BIS). Results Spillage of D3âCr in the urine was greater in women than men. D3âCrn enrichment and the ratio of Cr/Crn were used in an algorithm to calculate Cr pool size and muscle mass. Specifically, an algorithm was developed for the estimation of spillage based on the relationship between the fasting Cr/Crn ratio and the cumulative proportion of the D3âCr dose excreted over 3 days based on 24âh urine collections. Muscle mass corrected using the algorithm based on fasting urine levels correlated (r = 0.9967, P < 0.0001) with that corrected by measuring D3âCr dose excreted. Muscle mass measured by D3âCrn enrichment also correlated (r = 0.8579, P < 0.0001, algorithm corrected) with that measured by 24âh Crn excretion. Muscle mass measured by D3âCr dilution method correlated with intracellular water by BIS, whether using spillage corrected by the algorithm (r = 0.9041, P < 0.0001) or measured by 3 day D3âCr losses (r = 0.91, P < 0.0001) and similarly correlated with fatâfree mass by BIA (r = 0.8857 and 0.8929, P < 0.0001, respectively). Conclusions The D3âCr dilution method is further validated here as a nonâinvasive, easyâtoâuse test for measuring muscle mass. The technical issue of D3âCr spillage can be corrected for with a simple algorithm based on fasting spot urine samples. Muscle mass by Cr dilution potentially has broad applications in clinical and research settings
New product innovations, information signalling and industry competition
This paper examines the impact of new product innovations on the market values of industry rivals. The evidence indicates that, on average, firms introducing new products experience a significantly positive valuation effect at announcement, while portfolios of industry rivals experience a significant negative valuation effect. This result is consistent with the hypothesis that signals of adverse changes in the competitive position of rivals dominate expected benefits from an innovation spillover. Crosssectional analysis of the announcement period returns reveals that the competitive effects are more pronounced in industries with less concentration and high leverage. Additionally, we find that industry rivals perform as well as the new product firms during the three years following the innovations. We conclude that over a longer period, rival firms are able to respond to the competitive disadvantage of the new product by some alternative innovation or an imitation.