Management of hyperlipidaemia

Copyright © 2005 Royal Australian College of General Practitioners Copyright to Australian Family Physician. Reproduced with permission. Permission to reproduce must be sought from the publisher, The Royal Australian College of General Practitioners.BACKGROUND: Hyperlipidaemia is a general term for elevated concentrations of any or all lipids in the plasma. An elevated cholesterol is one of several risk factors for coronary heart disease (CHD). In Australia, the use of cholesterol lowering drugs, mainly statins, consumes over $880 million or 16% of the Pharmaceutical Benefits Scheme drug budget and is growing. OBJECTIVE: This article focusses on primary hypercholesterolaemia, its relationship with CHD, and its management in the community setting. DISCUSSION There is strong evidence that treating middle aged men with statins who have established CHD will reduce overall mortality, CHD morbidity, or mortality and stroke. There is weaker but reasonable evidence for treating men aged over 65 years and women of any age who have CHD, or people without CHD but at high risk. There may be some benefits for patients with stroke and peripheral vascular disease who are at risk of CHD. While discontinuation rates are high, the occurrence of serious adverse reactions are infrequent.Nigel Stocks, James Allan and Peter R. Mansfiel

Viscosity of High Energy Nuclear Fluids

Relativistic high energy heavy ion collision cross sections have been interpreted in terms of almost ideal liquid droplets of nuclear matter. The experimental low viscosity of these nuclear fluids have been of considerable recent quantum chromodynamic interest. The viscosity is here discussed in terms of the string fragmentation models wherein the temperature dependence of the nuclear fluid viscosity obeys the Vogel-Fulcher-Tammann law.Comment: 6 pages, ReVTeX 4 format, two figures, *.eps forma

Statin prescribing in Australia: socioeconomic and sex differences - A cross-sectional study

The document attached has been archived with permission from the editor of the Medical Journal of Australia. An external link to the publisher’s copy is included.OBJECTIVE: To assess if there are any differences in statin prescribing across Australia by socioeconomic status or sex and to relate prescribing rates to coronary heart disease (CHD) mortality rates. DESIGN: Cross-sectional study using data on statin prescribing by age, sex and patient postcode for the period May to December 2002. SETTING AND PARTICIPANTS: The Australian population, stratified by sex and quintile of Index of Relative Socio-Economic Disadvantage (IRSD). MAIN OUTCOME MEASURES: Age-standardised rates of statin scripts per 1000 population per month for each sex and IRSD quintile. RESULTS: 9.1 million prescriptions for statins were supplied between May and December 2002, for a total cost of $570 million. The age-standardised rates for statin prescribing in women varied from 56.9 (95% CI, 56.6–57.2) scripts per 1000 population per month in the most disadvantaged socioeconomic quintile through 53.4 (95% CI, 53.0–53.7), 50.3 (95% CI, 50.0–50.6), 48.4 (95% CI, 48.1–48.7) to 46.3 (95% CI, 46.0–46.6) in the least disadvantaged quintile. For men the figures were 52.6 (95% CI, 52.3–52.9), 50.9 (95% CI, 50.6–51.2), 48.8 (95% CI, 48.6–49.1), 47.7 (95% CI, 47.4–47.9), and 51.9 (95% CI, 51.6–52.2). There was a significant linear association between statin prescribing and CHD mortality by quintile of socioeconomic disadvantage in women (weighted least squares slope, 0.380; 95% CI, 0.366 to 0.395; P < 0.0001), but not in men (slope, −0.002; 95% CI, −0.010 to 0.006; P = 0.65). Conclusions: Our results suggest that in men there is either overprescribing of statins in the highest socioeconomic quintile or underprescribing in the lowest. Furthermore, contrary to expectation, women — relative to men — are prescribed statins at higher rates at lower levels of risk (using CHD deaths as a proxy MJA 2004; 180: 229–231 measure of risk).Nigel P Stocks, Philip Ryan, Heather McElroy and James Alla

The Influence of Fatty Acid Ester Alcohol Moiety Molecular Structure on Diesel Combustion and Emissions

At present, biodiesel is primarily comprised of fatty acid methyl esters (FAMEs) obtained by the transesterification of a variety of vegetable oils with methanol. However, transesterification can be carried out with a wide variety of alcohols other than methanol. This paper presents experimental studies carried out on a diesel engine supplied with a range of single-molecule fuels to investigate the effect of fuel molecular structure on combustion and emissions. Eight fatty acid esters that can be produced by transesterification of vegetable oils and animal fats using methanol, ethanol, n-propanol, n-butanol, iso-propanol, iso-butanol, and tert-butanol were investigated. The aim was to ascertain the way in which the structure of the alcohol reactant and the corresponding moiety in the ester molecule affects combustion and emissions. Previously obtained experimental results from a second set of 18 nonoxygenated acyclic hydrocarbons were used to assist the interpretation of the test results from the eight fatty acid esters. The engine tests were carried out at constant injection timing, and they were repeated at constant ignition timing and at constant ignition delay, the latter being achieved through the addition to the various fuels of small quantities of ignition improver (2-ethyl hexyl nitrate). Only small differences in ignition quality of the fatty acid esters were found with variation of the molecular structure of the alcohol moiety. Where present, differences in ignition delay were found to be the main driver of both combustion phasing and emissions production. With the effect of ignition delay isolated, physical properties of the esters, such as thermal degradation prior to vaporization and boiling point, were found to exert an influence on levels of particulate and NOx emissions

Combustion and emissions characteristics of toluene/n-heptane and 1-octene/n-octane binary mixtures in a direct injection compression ignition engine

Successfully designing and making effective of use of the next generation of liquid fuels, which will be derived from a range of biomass and fossil sources, requires an understanding of the interactions between structurally similar and dissimilar fuel components when utilised in current engine technology. Interactions between fuel components can influence the release of energy and production of harmful emissions in compression ignition combustion through determination of the autoignition behavior of the fuel. This paper presents experimental studies carried out in a single-cylinder engine supplied with a range of binary mixture fuels to investigate the effect of fuel component interactions on autoignition in direct injection compression ignition. A range of binary mixtures consisting of toluene and n-heptane and also 1-octene and n-octane were tested so as to observe respectively the effect of an aromatic compound and an alkene on n-alkane combustion and emissions. The engine tests were carried out at constant injection timing and they were repeated at constant ignition timing and at constant ignition delay, the latter being achieved through the addition to the various fuels of small quantities of ignition improver (2-ethylhexyl nitrate). Increasing the presence of toluene in the toluene/n-heptane binary mixtures resulted in an increased ignition delay time and generated a distinct two stage ignition process. An increased level of 1-octene in the binary mixtures of 1-octene/n-octane was also found to increase ignition delay, though to a much lesser extent than toluene in the case of the toluene/n-heptane mixtures. Interactions between the fuel components during the ignition delay period appear important in the case of the toluene/n-heptane mixtures but not those of 1-octene/n-octane. At constant injection and constant ignition timings, the combustion phasing and the level of emissions produced by each binary mixture were primarily driven by the ignition delay time. With ignition delay equalised, an effect of adiabatic flame temperature on NOx production was visible

Bulk and surface energetics of lithium hydride crystal: benchmarks from quantum Monte Carlo and quantum chemistry

We show how accurate benchmark values of the surface formation energy of crystalline lithium hydride can be computed by the complementary techniques of quantum Monte Carlo (QMC) and wavefunction-based molecular quantum chemistry. To demonstrate the high accuracy of the QMC techniques, we present a detailed study of the energetics of the bulk LiH crystal, using both pseudopotential and all-electron approaches. We show that the equilibrium lattice parameter agrees with experiment to within 0.03 %, which is around the experimental uncertainty, and the cohesive energy agrees to within around 10 meV per formula unit. QMC in periodic slab geometry is used to compute the formation energy of the LiH (001) surface, and we show that the value can be accurately converged with respect to slab thickness and other technical parameters. The quantum chemistry calculations build on the recently developed hierarchical scheme for computing the correlation energy of a crystal to high precision. We show that the hierarchical scheme allows the accurate calculation of the surface formation energy, and we present results that are well converged with respect to basis set and with respect to the level of correlation treatment. The QMC and hierarchical results for the surface formation energy agree to within about 1 %.Comment: 16 pages, 4 figure

Organometallic mediated radical polymerization

Controlled radical polymerization has become increasingly important over the past decade and a half, allowing for the facile synthesis of specific macromolecular architectures with excellent control over the chemical and physical properties. This article presents an organized and detailed review of one particular CRP technique, organometallic mediated radical polymerization (OMRP), focusing on the individual catalysts developed, their efficacy and monomer scope. Rhodium, cobalt, molybdenum, osmium, iron, palladium, titanium, chromium and vanadium mediated radical polymerizations are presented alongside organo-main group mediated reactions. A separate section reviews the types of copolymers which have been synthesized using OMRP techniques. An attempt is made to unify the many disparate names which have previously been used for OMRP by virtue of the common mechanistic aspects displayed by the different catalyst systems. A mechanistic discussion highlights the similarities and differences between these systems and examines the interplay between reversible termination and degenerative transfer OMRP and competing 1-electron redox processes

Light attenuation characteristics of glacially-fed lakes

Transparency is a fundamental characteristic of aquatic ecosystems and is highly responsive to changes in climate and land use. The transparency of glacially-fed lakes may be a particularly sensitive sentinel characteristic of these changes. However, little is known about the relative contributions of glacial flour versus other factors affecting light attenuation in these lakes. We sampled 18 glacially-fed lakes in Chile, New Zealand, and the U.S. and Canadian Rocky Mountains to characterize how dissolved absorption, algal biomass (approximated by chlorophyll a), water, and glacial flour contributed to attenuation of ultraviolet radiation (UVR) and photosynthetically active radiation (PAR, 400–700 nm). Variation in attenuation across lakes was related to turbidity, which we used as a proxy for the concentration of glacial flour. Turbidity-specific diffuse attenuation coefficients increased with decreasing wavelength and distance from glaciers. Regional differences in turbidity-specific diffuse attenuation coefficients were observed in short UVR wavelengths (305 and 320 nm) but not at longer UVR wavelengths (380 nm) or PAR. Dissolved absorption coefficients, which are closely correlated with diffuse attenuation coefficients in most non-glacially-fed lakes, represented only about one quarter of diffuse attenuation coefficients in study lakes here, whereas glacial flour contributed about two thirds across UVR and PAR. Understanding the optical characteristics of substances that regulate light attenuation in glacially-fed lakes will help elucidate the signals that these systems provide of broader environmental changes and forecast the effects of climate change on these aquatic ecosystems

Ray helicity: a geometric invariant for multi-dimensional resonant wave conversion

For a multicomponent wave field propagating into a multidimensional conversion region, the rays are shown to be helical, in general. For a ray-based quantity to have a fundamental physical meaning it must be invariant under two groups of transformations: congruence transformations (which shuffle components of the multi-component wave field) and canonical transformations (which act on the ray phase space). It is shown that for conversion between two waves there is a new invariant not previously discussed: the intrinsic helicity of the ray