Experimental-theoretical Landau energy level data and its use in making p-Ge laser transition assignments

Landau energy levels are determined from cyclotron resonance absorption data and compared to theoretical calculations. Energy level diagrams are presented to graphically display the nonequal energy level spacings and identify absorption transitions. This information is then used to make transition assignments responsible for the p-Ge laser signals seen by V. N. Shastin et al. and C. Kremser et al. This work suggests that the p-Ge laser yields signals via the following transitions: (a) the expected cyclotron transitions for Δn=1, (b) harmonic cyclotron transitions for Δn=2, 3, (c) light-to-heavy hole transitions and (d) light hole to acceptor level transitions. The material of this paper should be of aid in the study of the pumping-oscillation cycle of the p-Ge laser.     

Reduction of O-linked N-acetylglucosamine-modified assembly protein-3 in Alzheimer's disease

Abnormal protein processing and modification is associated with Alzheimer's disease (AD) pathology. The role of phosphorylation in AD has been studied extensively because the presumed abnormal phosphorylation of tau protein is believed to play a role in the formation of paired helical filaments. Glycosylation with O-linked N-acetylglucosamine (O-GlcNAc) to serine and threonine residues is a dynamic protein modification of intracellular proteins, and it shares similar features with protein phosphorylation. In this study, O-GlcNAc glycosylation of proteins from autopsied human brains with confirmed AD and non-AD age-matched controls was examined. O-GlcNAcylation was demonstrated by labeling protein extracts with [3H]galactose in the presence of galactosyltransferase and subsequent analyses of saccharide-protein linkage and saccharide structure. The number of O-GlcNAc-containing proteins and the overall O-GlcNAc level do not appear to be different between AD and control brain tissues. The only significant change observed is a marked reduction of O-GlcNAcylated clathrin assembly protein-3 (AP-3) in AD. The reduction is more evident in brain neocortical regions, and there appears to be a negative correlation between O-glycosylated AP-3 and the density of neurofibrillary tangles. These data suggest a possible association between the O-glycosylated AP-3 and AD pathology.     

Very narrow linewidth asymmetric cladding InGaAs-GaAs ridge waveguide distributed Bragg reflector lasers

Asymmetric cladding InGaAs-GaAs ridge waveguide distributed Bragg reflector (RW-DBR) lasers are demonstrated with a spectral linewidth as low as 39 kHz for an output power of 24 mW. The fabrication requires only a single standard epitaxial growth of a laser structure while the use of a thin top cladding layer allows for a shallow reactive ion etch of the distributed Bragg reflector. These RW-DBR lasers have a threshold current of 12.4 mA, a slope of 0.3 W/A, and over 40 dB side-mode suppression at a wavelength of 1010 nm.     

Application of the response surface method of uncertainty analysis to establish distributions of FRAP-S3 calculated stored energy for PWR-type fuels

An uncertainty analysis was performed using the steady state fuel rod analysis program, FRAP-S3, to establish burnup-dependent distributions of fuel stored energy. The response surface methodology used for conducting the analysis is briefly discussed. The distributions of fuel stored energy obtained as a result of the uncertainty analysis reflect uncertainties in the FRAP-S3 model in addition to uncertainties in PWR fuel rod design and operating power. An assessment is made of the adequacy of these distributions to represent initial accident conditions for a typical PWR core. The relative influence of individual input variables on the integral uncertainty of computed output is discussed. Applications of the results of this study are presented. Emphasis is placed upon the utilization of the results to quantify evaluation model conservatism.     

Defining and implementing a 'no lifting' standard

Following the launch this spring of the RCN's campaign to reduce injuries from manual lifting of patients, this article describes the main policies and guidelines relating to lifting and handling, and tells how these were used to develop and implement a 'no lifting' standard on an elderly care ward.     

Diradylglycerols alter fatty acid inhibition of monoacylglycerol acyltransferase activity in Triton X-100 mixed micelles

The activity of hepatic monoacylglycerol acyltransferase (MGAT) (EC 2.3.1.22), a developmentally expressed microsomal enzyme, is inhibited by long-chain fatty acids, and stimulated by its product 1, 2-diacyl-sn-glycerol. Because the quantities of fatty acids and diacylglycerols are likely to vary in membranes during different physiological conditions and could thereby alter MGAT activity, we examined their combined effects on MGAT in Triton X-100/phospholipid mixed micelles. MGAT's product, 1,2-diC18:1-sn-glycerol, which is also normally a cooperative activator of the activity, reversed the 50% inhibition caused by 10 mol % oleic acid. The presence of oleic acid also allowed low concentrations (<10 mol %) of 1, 2-diC18:1-sn-glycerol to stimulate MGAT activity without the lag that is observed in the absence of fatty acid. At 12.6 mol %, 1, 2-monoC18:1-sn-glycerol ether, which alone has no effect on MGAT activity, became an activator in the presence of 10 mol % oleic acid. Kinetic studies revealed that in the presence of 15 mol % oleic acid, 1,2-diC18:1-sn-glycerol ether increased the apparent Vmax by 3. 8-fold while minimally altering the apparent Km for palmitoyl-CoA. Other neutral lipids including tri-C18:1-glycerol, ceramide, and cholesterol oleate did not stimulate MGAT in either the presence or the absence of fatty acid. Assay conditions altered MGAT's apparent relative preferences for potential monoradylglycerol substrates. The presence of phospholipids and of MGAT's 1,2-diacyl-sn-glycerol product increased the enzyme's apparent preference for its 2-monoacyl-sn-glycerol substrate by selectively increasing the apparent Vmax 2.7-fold only when 2-monoC18:1-sn-glycerol was the substrate. Thus, in addition to previously reported regulation of MGAT by phospholipids and intracellular lipid second messengers, these studies lend additional support to the hypothesis that changes in other membrane-associated lipids, such as long-chain fatty acids and diradylglycerols, may also profoundly alter the activity of MGAT.     

Excess mortality in England and Wales, and in Greater London, during the 1995 heatwave

STUDY OBJECTIVE: To assess the impact on mortality of the heatwave in England and Wales during July and August 1995 and to describe any difference in mortality impact between the Greater London urban population and the national population. DESIGN: Analysis of variation in daily mortality in England and Wales and in Greater London during a five day heatwave in July and August 1995, by age, sex, and cause. SETTING: England and Wales, and Greater London. MAIN RESULTS: An estimated 619 extra deaths (8.9% increase, approximate 95% confidence interval 6.4, 11.3%) were observed during this heatwave in England and Wales, relative to the expected number of deaths based on the 31-day moving average for that period. Excess deaths were apparent in all age groups, most noticeably in women and for deaths from respiratory and cerebrovascular disease. Using published daily mortality risk coefficients for air pollutants in London, it was estimated that up to 62% of the excess mortality in England and Wales during the heatwave may be attributable to concurrent increases in air pollution. In Greater London itself, where daytime temperatures were higher (and with lesser falls at night), mortality increased by 16.1% during the heatwave. Using the same risk coefficients to estimate the excess mortality apparently attributable to air pollution, more than 60% of the total excess in London was apparently attributable to the effects of heat. CONCLUSION: Analysis of this episode shows that exceptionally high temperatures in England and Wales, though rare, do cause increases in daily mortality.