Beyond the Thin Lens Approximation

We obtain analytic formulae for the null geodesics of Friedmann-Lema\^{\i}tre-Robertson-Walker spacetimes with scalar perturbations in the longitudinal gauge. From these we provide a rigorous derivation of the cosmological lens equation, and obtain an expression for the magnification of a bundle of light rays without restriction to static or thin lens scenarios. We show how the usual magnification matrix naturally emerges in the appropriate limits.Comment: 37 pages plus 3 appended figures, plain TeX. Submitted to Ap

Sphingosine kinase 2 and multiple myeloma

News on: Sphingosine kinase 2 inhibition synergises with bortezomib to target myeloma by enhancing endoplasmic reticulum stress, by Wallington-Beddoe et al. Oncotarget. 2017; doi: 10.18632/oncotarget.17115

Weak lensing deflection of three-point correlation functions

Weak gravitational lensing alters the apparent separations between observed sources, potentially affecting clustering statistics. We derive a general expression for the lensing deflection which is valid for any three-point statistic, and investigate its effect on the three-point clustering correlation function. We find that deflection of the clustering correlation function is greatest at around $z=2$. It is most prominent in regions where the correlation function varies rapidly, in particular at the baryon acoustic oscillation scale where it smooths out the peaks and troughs, reducing the peak-to-trough difference by about 0.1 percent at $z=1$ and around 2.3 percent at $z=10$. The modification due to lensing deflection is typically at the per cent level of the expected errors in a Euclid-like survey and therefore undetectable.Comment: 15 pages + appendices, 7 figures, minor changes to match version published in JCA

Bayesian meta-analysis for identifying periodically expressed genes in fission yeast cell cycle

The effort to identify genes with periodic expression during the cell cycle from genome-wide microarray time series data has been ongoing for a decade. However, the lack of rigorous modeling of periodic expression as well as the lack of a comprehensive model for integrating information across genes and experiments has impaired the effort for the accurate identification of periodically expressed genes. To address the problem, we introduce a Bayesian model to integrate multiple independent microarray data sets from three recent genome-wide cell cycle studies on fission yeast. A hierarchical model was used for data integration. In order to facilitate an efficient Monte Carlo sampling from the joint posterior distribution, we develop a novel Metropolis--Hastings group move. A surprising finding from our integrated analysis is that more than 40% of the genes in fission yeast are significantly periodically expressed, greatly enhancing the reported 10--15% of the genes in the current literature. It calls for a reconsideration of the periodically expressed gene detection problem.Comment: Published in at http://dx.doi.org/10.1214/09-AOAS300 the Annals of Applied Statistics (http://www.imstat.org/aoas/) by the Institute of Mathematical Statistics (http://www.imstat.org

A Simulator Based Evaluation of Speed Reduction Measures for Rural Arterial Roads

In Great Britain accident rates on rural roads are not falling as fast as those on urban roads. In 1993 the number of casualties from accidents on rural A roads was 4% higher than the average for 1981-85, which is the baseline for the Department of Transport target of a one third reduction in road accident casualties by the year 2000. Driving too fast for the conditions is a major factor in accident causation. High speeds in conjunction with the varying geometric conditions common on rural single-carriageway A roads, result in a fatal accident rate which is higher than that for any other type of road. The aim of the research was to investigate, in a safe and controlled manner using the University of Leeds Advanced Driving Simulator, the effectiveness of a variety of measures for reducing driver speeds on rural single-carriageway arterial roads, in order to identify practical and cost-effective combinations of treatments to reduce both the frequency and severity of accidents on such roads. Treatments appropriate to each of three situations were investigated. These were: (1) treatments that reduce speed and speed variance on fairly straight roads (general treatments); (2) treatments that reduce curve entry speeds for sharp bends; (3) treatments that reduce speeds on the approach to and through villages. Treatments investigated included the use of road markings to reduce lane width or produce horizontal deflection; the use of signs both on posts and on the road surface; and the use of optical illusions to affect the driver's perception of speed or road width. Many of the treatments have been used previously, but few have been evaluated in a controlled way. The first phase of the research involved the evaluation of each individual treatment. The treatments were evaluated with respect to their effect on speed, vehicle lateral position, and incidence of overtaking. The second phase of the research involved the evaluation of variations on and combinations of the most effective treatments. Substantial reductions in speeds were obtained by some of the treatments evaluated, for all three situations studied. There were also reductions in speed variance. These reductions are significant both in statistical and practical road safety terms. For the village situation the most effective combination of treatments was the chicane without hatching, yellow or white transverse lines throughout the village, and countdown speed limit signs on the approach to the village. For the bend treatments the most effective treatments were transverse lines with reducing spacing (including a central area filled with transverse lines); a central hatched area; a Wundt illusion (a series of chevrons with increasing angles but constant spacing, pointing towards the driver); and hatched areas at the edges of the road. Further speed reductions may be produced by combining one of the above treatments with the most effective sign treatments — SLOW or a triangular, warning sign style, advisory speed sign painted on the road surface. For the general treatments all those which involved lane narrowing produced speeds significantly different from the control. Shoulders delineated by continuous lines were more effective, than those delineated by broken lines. Shoulder width was not important, but carriageway width was. For central hatching, type of delineation and width of hatched area was not important. The location (central/edge) and type (removing carriageway or lane space) of the narrowing was not important

Cyclic AMP signalling in pancreatic islets

Cyclic 3'5'AMP (cAMP) is an important physiological amplifier of glucose-induced insulin secretion by the pancreatic islet β-cell, where it is formed by the activity of adenylyl cyclases, which are stimulated by glucose, through elevation in intracellular calcium concentrations, and by the incretin hormones (GLP-1 and GIP). cAMP is rapidly degraded in the pancreatic islet β-cell by various cyclic nucleotide phosphodiesterase (PDE) enzymes. Many steps involved in glucose-induced insulin secretion are modulated by cAMP, which is also important in regulating pancreatic islet β-cell differentiation, growth and survival. This chapter discusses the formation, destruction and actions of cAMP in the islets with particular emphasis on the β-cell

Five-Letter Internal Palidromes

Most Word Ways readers are attuned to letter-patterns. One of the most commonly-encountered ones is the internal palindrome, as in REVERse or diVISIVe. For years I have been collecting words with internal palindromes of five or more letters. I sent the editor a type-collections of 336 five-letter examples, from mACACA to piZAZZ; he added over one hundred more from a perusal of Jack Levine\u27s list of pattern words, and solicited the help of Dana Richards in searching the Air Force list of Webster\u27s Second by command is presented on the following pages. In the interest of brevity only one example for each pattern is given, and words not found in either Webster\u27s Second or Third Editions are tagged according to the following codes

Sphingosine kinases : emerging structure function insights

Sphingosine kinases (SK1 and SK2) catalyse the conversion of sphingosine into sphingosine 1-phosphate and control fundamental cellular processes, including cell survival, proliferation, differentiation, migration, and immune function. In this review, we highlight recent breakthroughs in the structural and functional characterisation of SK1 and these are contextualised by analysis of crystal structures for closely related prokaryotic lipid kinases. We identify a putative dimerisation interface and propose novel regulatory mechanisms governing structural plasticity induced by phosphorylation and interaction with phospholipids and proteins. Our analysis suggests that the catalytic function and regulation of the enzymes might be dependent on conformational mobility and it provides a roadmap for future interrogation of SK1 function and its role in physiology and disease

Two More Electronic Spellers

It was with a great deal of interest that I read the article in the May 1988 issue of Word Ways entitled The Electronic Speller by Faith Eckler. Soon after that I noticed the appearance of a device known as the Spelling Ace on top of a showcase in the Sight and Sound (Electronics) department at the store at which I am employed. After toying with it a number of time, my first notion was that The Electronic Speller described this gadget. Alas, it didn\u27t, but I enjoyed her article anyway