Homocysteine levels and treatment effect in the prospective study of pravastatin in the elderly at risk

Objectives: To assess the effect of preventive pravastatin treatment on coronary heart disease (CHD) morbidity and mortality in older persons at risk for cardiovascular disease (CVD), stratified according to plasma levels of homocysteine.<p></p> Design: A post hoc subanalysis in the PROspective Study of Pravastatin in the Elderly at Risk (PROSPER), started in 1997, which is a double-blind, randomized, placebo-controlled trial with a mean follow-up of 3.2 years.<p></p> Setting: Primary care setting in two of the three PROSPER study sites (Netherlands and Scotland).<p></p> Participants: Individuals (n = 3,522, aged 70–82, 1,765 male) with a history of or risk factors for CVD were ranked in three groups depending on baseline homocysteine level, sex, and study site.<p></p> Intervention: Pravastatin (40 mg) versus placebo.<p></p> Measurements: Fatal and nonfatal CHD and mortality.<p></p> Results: In the placebo group, participants with a high homocysteine level (n = 588) had a 1.8 higher risk (95% confidence interval (CI) = 1.2–2.5, P = .001) of fatal and nonfatal CHD than those with a low homocysteine level (n = 597). The absolute risk reduction in fatal and nonfatal CHD with pravastatin treatment was 1.6% (95% CI = −1.6 to 4.7%) in the low homocysteine group and 6.7% (95% CI = 2.7–10.7%) in the high homocysteine group (difference 5.2%, 95% CI = 0.11–10.3, P = .046). Therefore, the number needed to treat (NNT) with pravastatin for 3.2 years for benefit related to fatal and nonfatal CHD events was 14.8 (95% CI = 9.3–36.6) for high homocysteine and 64.5 (95% CI = 21.4–∞) for low homocysteine.<p></p> Conclusion: In older persons at risk of CVD, those with high homocysteine are at highest risk for fatal and nonfatal CHD. With pravastatin treatment, this group has the highest absolute risk reduction and the lowest NNT to prevent fatal and nonfatal CHD.<p></p&gt

COMPTEL observations of the quasar PKS 0528+134 during the first 3.5 years of the CGRO mission

The COMPTEL observations of the blazar-type quasar PKS 0528+134 in the energy range 0.75 MeV to 30 MeV carried out between April 1991 and September 1994 have been analyzed. During the first two years PKS 0528+134 was most significantly detected at energies above 3 MeV. During the last year there is only evidence for the quasar at energies below 3 MeV indicating a spectral change. The time-averaged COMPTEL energy spectrum between 0.75 MeV and 30 MeV is well represented by a power-law shape. Spectra collected from different observational periods reveal different power-law shapes: a hard state during flaring observations reported by EGRET, and a soft state otherwise. The combined simultaneous EGRET and COMPTEL spectra indicate these two spectral states as well. During low intensisty gamma-ray phases no spectral break is obvious from the combined COMPTEL and EGRET measurements. For the gamma-ray flaring phases however, the combined COMPTEL and EGRET data require a spectral bending at MeV-energies. By fitting broken power-law functions the best-fit values for the break in photon index range between 0.6 and 1.7, and for the break energy between ~5 MeV and ~20 MeV. Because the flux values measured by COMPTEL below 3 MeV in both states are roughly equal, the observations would be consistent with an additional spectral component showing up during gamma-ray flaring phases of PKS 0528+134. Such a component could be introduced by e.g. a high-energy electron-positron population with a low-energy cutoff in their bulk Lorentz factor distribution. The multiwavelength spectrum of PKS 0528+134 for gamma-ray flaring phases shows that the major energy release across the entire electro-magnetic spectrum is measured at MeV-energies.Comment: 10 pages, 8 postscript figures, latex, to appear in: A&A 328, 33 (1997

COMPTEL Observations of AGN at MeV-Energies

The COMPTEL experiment aboard CGRO, exploring the previously unknown sky at MeV-energies, has so far detected 10 Active Galactic Nuclei (AGN): 9 blazars and the radio galaxy Centaurus A. No Seyfert galaxy has been found yet. With these results COMPTEL has opened the field of extragalactic Gamma-ray astronomy in the MeV-band.Comment: 4 pages, 2 figures including 1 color plot, to appear in the Proceedings of the 3rd INTEGRAL Workshop "The Extreme Universe", held in Taormina, Italy, 14-18 September 199

Ultimate performance of polymer:fullerene bulk heterojunction tandem solar cells

We present the model calculations to explore the potential of polymer:fullerene tandem solar cells. As an approach we use a combined optical and electrical device model, where the absorption profiles are used as starting point for the numerical current-voltage calculations. With this model a maximum power efficiency of 11.7% for single cells has been achieved as a reference. For tandem structures with a ZnO/poly(3,4-ethylenedioxythiophene)/ poly(styrenesulphonic acid) middle electrode an ultimate efficiency of 14.1% has been calculated. In the optimum configuration the subcell with the narrowest band gap is placed closest to the incoming light. Consequently, tandem structures are expected to enhance the performance of optimized single cells by about 20%. © 2011 American Institute of Physics

Diffuse Gamma-Ray Emission from Starburst Galaxies and M31

We present a search for high energy gamma-ray emission from 9 nearby starburst galaxies and M31 with the EGRET instrument aboard CGRO. Though the diffuse gamma-ray emission from starburst galaxies was suspected to be detectable, we find no emission from NGC 253, M82 nor from the average of all 9 galaxies. The 2 sigma upper limit for the EGRET flux above 100 MeV for the averaged survey observations is 1.8 x 10-8 ph cm-2 s-1. From a model of the expected radio and gamma-ray emission, we find that the magnetic field in the nuclei of these galaxies is > 25 micro Gauss, and the ratio of proton and electron densities is < 400. The EGRET limits indicate that the rate of massive star formation in the survey galaxies is only about an order of magnitude higher than in the Milky Way. The upper limit to the gamma-ray flux above 100 MeV for M31 is 1.6 x 10-8 ph cm-2 s-1. At the distance of M31, the Milky Way flux would be over twice this value, indicating higher gamma-ray emissivities in our Galaxy. Therefore, since the supernova rate of the Milky Way is higher than in M31, our null detection of M31 supports the theory of the supernova origin of cosmic rays in galaxies.Comment: 17 pages, plus 1 Postscript figure, AAS Latex macros v4.0, accepted for publication in ApJ Main Journa

A review of outcomes and modes of presentation following liner dissociation from Harris-Galante uncemented acetabular components

Purpose Dissociation of the polyethylene liner is a known failure mechanism of the Harris Galante I and II uncemented acetabular components. The outcomes of revision surgery for this indication and the influence of time to diagnosis are not well described. Methods We report a series of 29 cases revised due to this failure mechanism. The median time from primary to revision surgery was 13 years. Results At a median of 4 years follow-up, the mean OHS was 34 (range 6-48) but results were poorer (mean 29; range 6-45) when the diagnosis and revision was delayed compared to when it was not (mean 39; range 20-48). A large proportion of our patients (n = 14) presented with sudden onset of symptoms with or without trauma. Osteolysis was common in this series but the cup was well fixed in 20/29 cases. There was macroscopic damage to the shell in all cases. Conclusions In our experience, prompt revision of liner dissociation optimises outcomes in this group of patients and radiology reporting alone is not sufficient to identify these cases. </jats:sec

Risk of cancer in first seven years after metal-on-metal hip replacement compared with other bearings and general population: linkage study between the National Joint Registry of England and Wales and hospital episode statistics

Objective To determine whether use of metal-on-metal bearing surfaces is associated with an increased risk of a diagnosis of cancer in the early years after total hip replacement and specifically with an increase in malignant melanoma and haematological, prostate, and renal tract cancers

Ultrafast Carrier Capture in Quantum Well Structures

We present an experimental and theoretical study of the carrier capture time into a semiconductor quantum well. The carrier capture time was obtained by measuring both the rise of the quantum well (QW) population using time-resolved luminescence measurements and the decay of the barrier population using pump-probe correlation experiments. In the first technique, we compare the QW rise-times after direct (below the barrier band gap) and indirect (above the barrier band gap) excitation in order to eliminate the effects of relaxation and exciton formation in the quantum well. We report the first experimental observation of oscillations in the carrier capture time between 3 and 20 ps as a function of quantum well thickness, obtained from both techniques. The observed capture times are, for the first time, in agreement with theoretical predictions from an ambipolar capture model

Device operation of conjugated polymer/zinc oxide bulk heterojunction solar cells

Solar cells based on a poly (p-phenylene vinylene) (PPV) derivative and zinc oxide nanoparticles can reach a power conversion efficiency of 1.6%. The transport of electrons and holes in these promising devices is characterized and it is found that the electron mobility is equal to 2.8 x 10(-9) m(2) V-1 s(-1), whereas the hole mobility amounts to 5.5 x 10(-10) m(2) V-1 s(-1). By modeling the current-voltage characteristics under illumination it is found that the performance of PPV/zinc oxide solar cells is limited by the charge-carrier mobilities. Subsequently, how to further improve the efficiency is discussed