Measurements of Photon and Neutral Pion Production in Heavy Ion Collisions at RHIC

Inclusive transverse momentum spectra of photons and neutral pions about mid-rapidity are presented for Au+Au collisions at sqrt(s_NN} = 130 GeV. Photon pair conversions have been reconstructed from charged tracks measured with the central Time Projection Chamber (TPC) of STAR. Contributions of the pi^0 -> \gamma\gamma decay in the inclusive photon spectra have been studied. It was found that this contribution begins to decrease at a transverse momentum of 1.65 GeV/c in the top 11% most central centrality class.Comment: 5 pages, 3 figures, contribution to the Proceedings of Quark Matter 2002, Nantes, France, July 18-24, 200

Determinants of stock market development in Nigeria using error correction model approach

Harnessing economic resources for national development is a major goal of governments; the stock market provides the medium through which funds could be mobilized and allocated for investments for development. This study sought to examine empirically whether stock market liquidity, savings rate, investment ratio, and foreign direct investment (FDI) were determinants of stock market development in Nigeria from 1970-2007. Using secondary data from the Central Bank of Nigeria Statistical Bulletin, 2007, and adopting co-integration and error correction mechanism (ECM), we found that stock market liquidity, savings rate, and one-period lagged stock market development were significant predictors of stock market development in Nigeria. It implies that improving liquidity of the market would impact the stock market; more domestic firms should be encouraged to enlist in the market and Nigerian businessmen abroad should enlist their  companies in their home stock market to increase liquidity in the market

Completeness and Incompleteness of Synchronous Kleene Algebra

Synchronous Kleene algebra (SKA), an extension of Kleene algebra (KA), was proposed by Prisacariu as a tool for reasoning about programs that may execute synchronously, i.e., in lock-step. We provide a countermodel witnessing that the axioms of SKA are incomplete w.r.t. its language semantics, by exploiting a lack of interaction between the synchronous product operator and the Kleene star. We then propose an alternative set of axioms for SKA, based on Salomaa's axiomatisation of regular languages, and show that these provide a sound and complete characterisation w.r.t. the original language semantics.Comment: Accepted at MPC 201

An experimental study on high-pressure water jets for paraffin scale removal in partially blocked production tubings

The common practice of using chemicals and solid-entrained liquids to remove soft scales in production tubings is associated with a high risk of contaminating the environment and eroding pipe internal surfaces. Due to the suspended solids, the current practices are also characterized by high pumping costs and are more problematic to rotating parts of machinery than freshwater. As a cheap and less risky alternative to these corrosive chemicals and liquids, this paper investigates the feasibility of utilizing multiple high-pressure (HP) water jets for the same objective. A total of 54 experimental trials were conducted to study the effects of four factors on the efficiency of scale removal with multiple flat-fan nozzles at an orientation of 25°. The factors investigated are (i) number of nozzles; (ii) spray injection pressure; (iii) stand-off distance between the spray nozzle and target scale; and (iv) condition of the production tubing: ambient and pressurized. Details of the experimental set-up, equipment and procedure are provided. The results of these controlled experiments show a positive correlation between descaling efficiency and spray injection pressure. The same set of experiments reveals a negative correlation between descaling efficiency and nozzle count, as well as between descaling efficiency and spray stand-off. However, for the scale samples and range of parameters investigated in this study, descaling efficiency did not exhibit significant dependency on the chamber conditions i.e. ambient vs. pressurized. The results of this study provide some insights into the feasibility of multiple HP water jets as a cleaner alternative to the use of corrosive chemicals and solid-entrained liquids to remove soft scales in production tubings in oil fields and other applications

Alcohol consumption and lifetime change in cognitive ability:a gene × environment interaction study

Studies of the effect of alcohol consumption on cognitive ability are often confounded. One approach to avoid confounding is the Mendelian randomization design. Here, we used such a design to test the hypothesis that a genetic score for alcohol processing capacity moderates the association between alcohol consumption and lifetime change in cognitive ability. Members of the Lothian Birth Cohort 1936 completed the same test of intelligence at age 11 and 70 years. They were assessed for recent alcohol consumption in later life and genotyped for a set of four single-nucleotide polymorphisms in three alcohol dehydrogenase genes. These variants were unrelated to late-life cognition or to socioeconomic status. We found a significant gene × alcohol consumption interaction on lifetime cognitive change (p = 0.007). Individuals with higher genetic ability to process alcohol showed relative improvements in cognitive ability with more consumption, whereas those with low processing capacity showed a negative relationship between cognitive change and alcohol consumption with more consumption. The effect of alcohol consumption on cognitive change may thus depend on genetic differences in the ability to metabolize alcohol

Genetic contributions to stability and change in intelligence from childhood to old age

Understanding the determinants of healthy mental ageing is a priority for society today1,2. So far, we know that intelligence differences show high stability from childhood to old age3,4 and there are estimates of the genetic contribution to intelligence at different ages5,6. However, attempts to discover whether genetic causes contribute to differences in cognitive ageing have been relatively uninformative7–10. Here we provide an estimate of the genetic and environmental contributions to stability and change in intelligence across most of the human lifetime. We used genome-wide single nucleotide polymorphism (SNP) data from 1,940 unrelated individuals whose intelligence was measured in childhood (age 11 years) and again in old age (age 65, 70 or 79 years)11,12. We use a statistical method that allows genetic (co)variance to be estimated from SNP data on unrelated individuals13–17. We estimate that causal genetic variants in linkage disequilibrium with common SNPs account for 0.24 of the variation in cognitive ability change from childhood to old age. Using bivariate analysis, we estimate a genetic correlation between intelligence at age 11 years and in old age of 0.62. These estimates, derived from rarely available data on lifetime cognitive measures, warrant the search for genetic causes of cognitive stability and change

The Lothian Birth Cohort 1936: a study to examine influences on cognitive ageing from age 11 to age 70 and beyond

BACKGROUND: Cognitive ageing is a major burden for society and a major influence in lowering people's independence and quality of life. It is the most feared aspect of ageing. There are large individual differences in age-related cognitive changes. Seeking the determinants of cognitive ageing is a research priority. A limitation of many studies is the lack of a sufficiently long period between cognitive assessments to examine determinants. Here, the aim is to examine influences on cognitive ageing between childhood and old age. METHODS/DESIGN: The study is designed as a follow-up cohort study. The participants comprise surviving members of the Scottish Mental Survey of 1947 (SMS1947; N = 70,805) who reside in the Edinburgh area (Lothian) of Scotland. The SMS1947 applied a valid test of general intelligence to all children born in 1936 and attending Scottish schools in June 1947. A total of 1091 participants make up the Lothian Birth Cohort 1936. They undertook: a medical interview and examination; physical fitness testing; extensive cognitive testing (reasoning, memory, speed of information processing, and executive function); personality, quality of life and other psycho-social questionnaires; and a food frequency questionnaire. They have taken the same mental ability test (the Moray House Test No. 12) at age 11 and age 70. They provided blood samples for DNA extraction and testing and other biomarker analyses. Here we describe the background and aims of the study, the recruitment procedures and details of numbers tested, and the details of all examinations. DISCUSSION: The principal strength of this cohort is the rarely captured phenotype of lifetime cognitive change. There is additional rich information to examine the determinants of individual differences in this lifetime cognitive change. This protocol report is important in alerting other researchers to the data available in the cohort

Profiles of physical, emotional and psychosocial wellbeing in the Lothian birth cohort 1936

<p>Abstract</p> <p>Background</p> <p>Physical, emotional, and psychosocial wellbeing are important domains of function. The aims of this study were to explore the existence of separable groups among 70-year olds with scores representing physical function, perceived quality of life, and emotional wellbeing, and to characterise any resulting groups using demographic, personality, cognition, health and lifestyle variables.</p> <p>Methods</p> <p>We used latent class analysis (LCA) to identify possible groups.</p> <p>Results</p> <p>Results suggested there were 5 groups. These included High (n = 515, 47.2% of the sample), Average (n = 417, 38.3%), and Poor Wellbeing (n = 37, 3.4%) groups. The two other groups had contrasting patterns of wellbeing: one group scored relatively well on physical function, but low on emotional wellbeing (Good Fitness/ Low Spirits,n = 60, 5.5%), whereas the other group showed low physical function but relatively well emotional wellbeing (Low Fitness/Good Spirits, n = 62, 5.7%). Salient characteristics that distinguished all the groups included smoking and drinking behaviours, personality, and illness.</p> <p>Conclusions</p> <p>Despite there being some evidence of these groups, the results also support a largely one-dimensional construct of wellbeing in old age—for the domains assessed here—though with some evidence that some individuals have uneven profiles.</p

The good, the bad and the twisted: a survey of ligand geometry in protein crystal structures

The protein databank now contains the structures of over 11,000 ligands bound to proteins. These structures are invaluable in applied areas such as structure-based drug design, but are also the substrate for understanding the energetics of intermolecular interactions with proteins. Despite their obvious importance, the careful analysis of ligands bound to protein structures lags behind the analysis of the protein structures themselves. We present an analysis of the geometry of ligands bound to proteins and highlight the role of small molecule crystal structures in enabling molecular modellers to critically evaluate a ligand model’s quality and investigate protein-induced strain