University of St Andrews

About: University of St Andrews is a education organization based out in St Andrews, Fife, United Kingdom. It is known for research contribution in the topics: Population & Laser. The organization has 16260 authors who have published 43364 publications receiving 1636072 citations. The organization is also known as: St Andrews University & University of St. Andrews.

A measurement of the cosmological mass density from clustering in the 2dF Galaxy Redshift Survey

Abstract: The large-scale structure in the distribution of galaxies is thought to arise from the gravitational instability of small fluctuations in the initial density field of the Universe. A key test of this hypothesis is that forming superclusters of galaxies should generate a systematic infall of other galaxies. This would be evident in the pattern of recessional velocities, causing an anisotropy in the inferred spatial clustering of galaxies. Here we report a precise measurement of this clustering, using the redshifts of more than 141,000 galaxies from the two-degree-field (2dF) galaxy redshift survey. We determine the parameter β = Ω ^(0.6)/b = 0.43 ± 0.07, where Ω is the total mass-density parameter of the Universe and b is a measure of the 'bias' of the luminous galaxies in the survey. (Bias is the difference between the clustering of visible galaxies and of the total mass, most of which is dark.) Combined with the anisotropy of the cosmic microwave background, our results favour a low-density Universe with Ω ≈ 0.3.

Discovery of a cool planet of 5.5 Earth masses through gravitational microlensing

Abstract: Over 170 extrasolar planets have so far been discovered, with a wide range of masses and orbital periods, but until last July no planet of Neptune's mass or less had been detected any more than 0.15 astronomical units (AU) from a normal star. (That's close — Earth is one AU from the Sun). On 11 July 2005 the OGLE Early Warning System recorded a notable event: gravitational lensing of light from a distant object by a foreground star revealed a small planet of about 5.5 Earth masses, orbiting at about 2.6 AU from the foreground star. This is the lowest known mass for an extrasolar planet orbiting a main sequence star, and its detection suggests that cool, sub-Neptune mass planets are more common than gas giants, as predicted by the favoured core accretion theory of planet formation. In the favoured core-accretion model of formation of planetary systems, solid planetesimals accumulate to build up planetary cores, which then accrete nebular gas if they are sufficiently massive. Around M-dwarf stars (the most common stars in our Galaxy), this model favours the formation of Earth-mass (M⊕) to Neptune-mass planets with orbital radii of 1 to 10 astronomical units (au), which is consistent with the small number of gas giant planets known to orbit M-dwarf host stars1,2,3,4. More than 170 extrasolar planets have been discovered with a wide range of masses and orbital periods, but planets of Neptune's mass or less have not hitherto been detected at separations of more than 0.15 au from normal stars. Here we report the discovery of a M⊕ planetary companion at a separation of au from a M⊙ M-dwarf star, where M⊙ refers to a solar mass. (We propose to name it OGLE-2005-BLG-390Lb, indicating a planetary mass companion to the lens star of the microlensing event.) The mass is lower than that of GJ876d (ref. 5), although the error bars overlap. Our detection suggests that such cool, sub-Neptune-mass planets may be more common than gas giant planets, as predicted by the core accretion theory.

The Kennedy pathway—De novo synthesis of phosphatidylethanolamine and phosphatidylcholine

Abstract: The glycerophospholipids phosphatidylcholine (PC) and phosphatidylethanolamine (PE) account for greater than 50% of the total phospholipid species in eukaryotic membranes and thus play major roles in the structure and function of those membranes. In most eukaryotic cells, PC and PE are synthesized by an aminoalcoholphosphotransferase reaction, which uses sn-1,2-diradylglycerol and either CDP-choline or CDP-ethanolamine, respectively. This is the last step in a biosynthetic pathway known as the Kennedy pathway, so named after Eugene Kennedy who elucidated it over 50 years ago. This review will cover various aspects of the Kennedy pathway including: each of the biosynthetic steps, the functions and roles of the phospholipid products PC and PE, and how the Kennedy pathway has the potential of being a chemotherapeutic target against cancer and various infectious diseases.

Lithium Diffusion in Graphitic Carbon

Abstract: Graphiticcarboniscurrentlyconsideredthestate-of-the-artmaterial for the negative electrode in lithium ion cells, mainly due to its high reversibility and low operating potential. However, carbon anodes exhibit mediocre charge/ discharge rate performance, which contributes to severe transport-induced sur- face structural damage upon prolonged cycling and limits the lifetime of the cell. Lithium bulkdiffusion in graphitic carbon is not yet completely understood, partly due to the complexity of measuring bulk transport properties in finite-sized nonisotropic particles. To solvethis problem forgraphite, weuse the Devanathan- Stachurski electrochemical methodology combined with ab initio computations to deconvolute and quantify the mechanism of lithium ion diffusion in highly oriented pyrolytic graphite (HOPG). The results reveal inherent high lithium ion diffusivityinthedirectionparalleltothegrapheneplane(∼10 -7 -10 -6 cm 2 s -1 ),as comparedtosluggishlithiumiontransportalonggrainboundaries(∼10 -11 cm 2 s -1 ), indicating the possibility of rational design of carbonaceous materials and com- posite electrodes with very high rate capability. SECTION Energy Conversion and Storage

Organisational culture and quality of health care

Abstract: “ A student of management and organisation theory could only be stunned by how little the efforts to improve quality [in health care] have learnt from current thinking in management and from the experience of other industries .” Christian Koeck BMJ 1998; 317: 1267–8. Health policy in much of the developed world is concerned with assessing and improving the quality of health care. The USA, in particular, has identified specific concerns over quality issues12 and a recent report from the Institute of Medicine pointed to the considerable toll of medical errors.3 In the UK a series of scandals has propelled quality issues to centre stage45 and made quality improvement a key policy area.6 But how are quality improvements to be wrought in such a complex system as health care? A recent issue of Quality in Health Care was devoted to considerations of organisational change in health care, calling it “the key to quality improvement”.7 In discussing how such change can be managed, the authors of one of the articles asserted that cultural change needs to be wrought alongside structural reorganisation and systems reform to bring about “a culture in which excellence can flourish”.8 A review of policy changes in the UK over the past two decades shows that these appeals for cultural change are not new but have appeared in various guises (box 1). However, talk of “culture” and “culture change” beg some difficult questions about the nature of the underlying substrate to which change programmes are applied. What is “organisational culture” anyway? It is to this issue that this paper is addressed.Many previous policy reforms in the National Health Service (NHS) have invoked the notion of cultural change. In the early 1980s the reforms inspired by Sir Roy Griffiths led …