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We have made a comparative study of the relative operational stability of bulk-heterojunction organic photovoltaic (OPV) devices utilising different hole transport layers (HTLs). OPV devices were fabricated based on a blend of the polymer PCDTBT with the fullerene PC70BM, and incorporated the different HTL materials PEDOT:PSS, MoOx and V2O5. Following 620 h of irradiation by light from a solar simulator, we find that devices using the PEDOT:PSS HTL retained the highest efficiency, having a projected T80 lifetime of 14500 h. [ABSTRACT FROM AUTHOR]

We report a comparative study based on the fabrication of polymer:fullerene photovoltaic (PV) devices incorporating carbazole, fluorene, and a PTB based co-polymer. We have explored the efficiency and performance of such devices when the active polymer:fullerene layer is deposited by spin-casting either under nitrogen or ambient conditions. We show that PV devices based on carbazole and fluorene based materials have very similar power conversion efficiencies when processed under both air and nitrogen, with other photobleaching measurements suggesting that such materials have comparatively enhanced photostability. Devices based on the PTB co-polymer, however, have reduced efficiency when processed in air. [ABSTRACT FROM AUTHOR]

Examines the differences between the interaction of antithrombotic agents with the hemostatic system of the young and adults. Side effects of antithrombotic agents in children; Potential advantages of low-molecular-weight heparin over for children; Thromboembolic and hemorrhagic complications of mechanical prosthetic heart valves with no antithrombotic therapy.

Patients with nonvalvular atrial fibrillation (AF) have an increased risk of stroke, but the absolute rate of stroke varies widely depending on coexistent vascular disease. We assessed the stroke rate and predictive value of two published schemes for stroke risk stratification in a population-derived cohort of 259 elderly people with nonvalvular AF followed for a median of 5.3 years. The rate of ischemic stroke was 2.8% per year (95% confidence interval [CI] 1.9, 3.9). Thirty-one percent were predicted to be at low risk, and their stroke rate was 1.7% per year (95% CI 0.6, 3.8). Many people with AF in this population-derived cohort had relatively low rates of stroke. Further studies to reliably stratify stroke risk in patients with AF are needed. [ABSTRACT FROM AUTHOR]

Objectives: To assess the effects of invasive procedures, hemostatic and clinical variables, the timing of beta-blocker therapy, and the doses of recombinant plasminogen activator (rt-PA) on hemorrhagic events.Design: A multicenter, randomized, controlled trial.Setting: Hospitals participating in the Thrombolysis in Myocardial Infarction, Phase II trial (TIMI II).Interventions: Patients received rt-PA, heparin, and aspirin. The total dose of rt-PA was 150 mg for the first 520 patients and 100 mg for the remaining 2819 patients. Patients were randomly assigned to an invasive strategy (coronary arteriography with percutaneous angioplasty [if feasible] done routinely 18 to 48 hours after the start of thrombolytic therapy) or to a conservative strategy (coronary arteriography done for recurrent spontaneous or exercise-induced ischemia). Eligible patients were also randomly assigned to either immediate intravenous or deferred beta-blocker therapy.Measurements: Patients were monitored for hemorrhagic events during hospitalization.Main Results: In patients on the 100-mg rt-PA regimen, major and minor hemorrhagic events were more common among those assigned to the invasive than among those assigned to the conservative strategy (18.5% versus 12.8%, P less than 0.001). Major or minor hemorrhagic events were associated with the extent of fibrinogen breakdown, peak rt-PA levels, thrombocytopenia, prolongation of the activated partial thromboplastin time (APTT) to more than 90 seconds, weight of 70 kg or less, female gender, and physical signs of cardiac decompensation. Immediate intravenous beta-blocker therapy had no important effect on hemorrhagic events when compared with delayed beta-blocker therapy. Intracranial hemorrhages were more frequent among patients treated with the 150-mg rt-PA dose than with the 100-mg rt-PA dose (2.1% versus 0.5%, P less than 0.001). The extent of the plasmin-mediated hemostatic defect was also greater in patients receiving the 150-mg dose.Conclusions: Increased morbidity due to hemorrhagic complications is associated with an invasive management strategy in patients with acute myocardial infarction. Our findings show the complex interaction of several factors in the occurrence of hemorrhagic events during thrombolytic therapy. [ABSTRACT FROM AUTHOR]

Purpose: To determine adherence with practice guidelines in a population-based cohort of elderly persons aged 70 years or older with atrial fibrillation.Subjects and Methods: This was a cross-sectional analysis of a subgroup of participants in the Cardiovascular Health Study, a prospective observational study involving four communities in the United States. Subjects were participants with atrial fibrillation on electrocardiogram at one or more yearly examinations from 1993 to 1995. The outcome measure was self-reported use of warfarin in 1995.Results: In 1995, 172 (4.1%) participants had atrial fibrillation together with information regarding warfarin use and no preexisting indication for its use. Warfarin was used by 63 (37%) of these participants. Of the 109 participants not reporting warfarin use, 92 (84%) had at least one of the clinical risk factors (aside from age) associated with stroke in patients with atrial fibrillation. Among participants not taking warfarin, 47% were taking aspirin. Several characteristics were independently associated with warfarin use, including age [odds ratio (OR) = 0.6 per 5-year increment, 95% CI 0.5-0.9], a modified mini-mental examination score <85 points [OR = 0.3, 95% confidence interval (CI) 0.1-0.9], and among patients without prior stroke, female sex (OR = 0.5, 95% CI 0.2-1.0).Conclusions: Despite widely publicized practice guidelines to treat patients who have atrial fibrillation with warfarin, most participants who had atrial fibrillation were at high risk for stroke but were not treated with warfarin. More studies are needed to determine why elderly patients with atrial fibrillation are not being treated with warfarin. [ABSTRACT FROM AUTHOR]