OPEC meetings, oil market volatility and herding behaviour in the Saudi Arabia stock market

We investigate the influence of oil market volatility and hand‐picked OPEC meetings data on herding tendency in the Saudi equity market. Our results show the presence of significant herding behaviour in the Saudi market; surprisingly this herding behaviour is independent of oil market volatility. Importantly, we find herding on and around the OPEC meeting days however this is only limited to a period of high global uncertainty that is, during the Global Financial Crisis period (GFC) of 2008–2010. However, when we filter out factor‐based herding in the Saudi equities, we also find persistent herding in the post GFC period. These results are consistent when we assess the impact of OPEC meetings using event windows of one to 5 days before and after the announcement. In consideration of the crucial role of OPEC in determining the oil prices, we explain our results of Saudi market herding on and around OPEC meeting days for the prior announcement ambiguity and corrections before, on and after the announcements on global supply. Our results show that this tendency has originated during the GFC, has persisted in the post‐GFC in the Saudi equities and surprisingly, is largely found absent in the periods when the Saudi equity market witnessed bullish market conditions. Our results are robust after accounting for common factor return variations in equity returns, the unconditional and conditional estimates of the volatility in oil prices and several event windows around OPEC meeting days

Drag Reduction by Polymers in Wall Bounded Turbulence

We address the mechanism of drag reduction by polymers in turbulent wall bounded flows. On the basis of the equations of fluid mechanics we present a quantitative derivation of the "maximum drag reduction (MDR) asymptote" which is the maximum drag reduction attained by polymers. Based on Newtonian information only we prove the existence of drag reduction, and with one experimental parameter we reach a quantitative agreement with the experimental measurements.Comment: 4 pages, 1 fig., included, PRL, submitte

Factors influencing use of essential surgical services in North-East India: a cross-sectional study of obstetric and gynaecological surgery

Introduction There continues to be a large gap between need and actual use of surgery in low-resource settings. While policy frequently focuses on expanding the supply of services, demand-side factors are at least as important in determining under utilisation and over utilisation. The aim of this study is to understand how these factors influence the use of selected essential obstetric and gynaecological surgical procedures in the underserved and remote setting of North-East India. Methods The study combines and makes use of data from a variety of surveys and routine systems. Descriptive analysis of variations in caesarean section, hysterectomy and sterilisation and then multivariate logit analysis of demand-side and supply-side factors on access to these services is undertaken. Results Surgical rates vary substantially both across and within North-East India, correlated with service capacity and socioeconomic status. Travel times to surgical facilities are associated with rates of caesarean section and hysterectomy but not sterilisation where services are much more deconcentrated. Travel is less important for surgery in private facilities where capacity is much more dispersed but dominated by the non-poor. The presence of non-doctor medical staff is associated with lower levels of surgical activity. Conclusion In low resource, remote settings policy interventions to improve access to services must recognise that surgical rates in low-resource settings are heavily influenced by demand-side factors. As well as boosting services, mechanisms need to mitigate demand-side barriers particularly distance and influence practice to encourage surgical intervention only where clinically indicated

Randomized Controlled Trials: How Can We Know “What Works”?

“Evidence-based” methods, which most prominently include randomized controlled trials, have gained increasing purchase as the “gold standard” for assessing the effect of public policies. But the enthusiasm for evidence-based research overlooks questions about the reliability and applicability of experimental findings to diverse real-world settings. Perhaps surprisingly, a qualitative study of British educators suggests that they are aware of these limitations and therefore take evidence-based findings with a much larger grain of salt than do policy makers. Their experience suggests that the real world is more heterogeneous than the world imagined by evidence-based policy enthusiasts

Giant ambipolar Rashba effect in a semiconductor: BiTeI

We observe a giant spin-orbit splitting in bulk and surface states of the non-centrosymmetric semiconductor BiTeI. We show that the Fermi level can be placed in the valence or in the conduction band by controlling the surface termination. In both cases it intersects spin-polarized bands, in the corresponding surface depletion and accumulation layers. The momentum splitting of these bands is not affected by adsorbate-induced changes in the surface potential. These findings demonstrate that two properties crucial for enabling semiconductor-based spin electronics -- a large, robust spin splitting and ambipolar conduction -- are present in this material.Comment: 4 pages, 3 figure

Synthesis of some new propanamide derivatives bearing 4- piperidinyl-1,3,4-oxadiazole, and their evaluation as promising anticancer agents

Purpose: To sequentially synthesize piperidine-4-carboxylic acid ethyl ester-appended 1,3,4-oxadiazole hybrids and to evaluate them as anticancer agents.Methods: Ethyl 1-[(4-methylphenyl)sulfonyl]-4-piperidinecarboxylate (1) was synthesized from 4- methylbenzenesulfonylchloride (a) and ethyl 4-piperidinecarboxylate (b). Compound (1) was converted into ethyl 1-[(4-methylphenyl)sulfonyl]-4-piperidine carbohydrazides (2) and 5-{1-[(4- methylphenyl)sulfonyl]-4-piperidinyl}-1,3,4-oxadiazole-2-thiol (3) respectively. A variety of aryl amine (4a-l) were treated with 2-bromopropionylbromide to synthesize an array of propanamide (5a-l). Finally, 5-{1-[(4-methylphenyl)sulfonyl]-4-piperidinyl}-1,3,4-oxadiazole-2-thiol (3) and propanamides (5a-l) were reacted to synthesize target compounds (6a-l). Purity compounds 6a-l was confirmed by spectroscopic techniques like (1H-NMR), (13C-NMR) and EI-MS. To determine their anticancer potential, the change in absorbance of mixture and cell line before and after incubation was determined.Results: All the compounds 6a-l were successfully synthesized in 73-85 % yield. Compounds 6h, 6j and 6e have low IC50 (±SD) values of 20.12 ± 6.20, 10.84 ± 4.2 and 24.57 ± 1.62 μM to act as strong anticancer agents relative to doxorubicin (0.92 ± 0.1 μM) used as a reference.Conclusion: The synthesized propanamide derivatives bearing 4-piperidinyl-1,3,4-oxadiazole are potential anticancer agents, but further studies, especially in vivo, are required to ascertain their therapeutic usefulness.Keywords: Ethyl isonipecotate, Propanamides, 1,3,4-Oxadiazole, Anti-cancer activit

Evidence for a singularity in ideal magnetohydrodynamics: implications for fast reconnection

Numerical evidence for a finite-time singularity in ideal 3D magnetohydrodynamics (MHD) is presented. The simulations start from two interlocking magnetic flux rings with no initial velocity. The magnetic curvature force causes the flux rings to shrink until they come into contact. This produces a current sheet between them. In the ideal compressible calculations, the evidence for a singularity in a finite time $t_c$ is that the peak current density behaves like $|J|_\infty \sim 1/(t_c-t)$ for a range of sound speeds (or plasma betas). For the incompressible calculations consistency with the compressible calculations is noted and evidence is presented that there is convergence to a self-similar state. In the resistive reconnection calculations the magnetic helicity is nearly conserved and energy is dissipated.Comment: 4 pages, 4 figure

Hydrogen effusion from tritiated amorphous silicon

Results for the effusion and outgassing of tritium from tritiated hydrogenated amorphous silicon (a-Si:H:T) films are presented. The samples were grown by dc-saddle field glow discharge at various substrate temperatures between 150 and 300 °C. The tracer property of radioactive tritium is used to detect tritium release. Tritium effusion measurements are performed in a nonvacuum ion chamber and are found to yield similar results as reported for standard high vacuum technique. The results suggest for decreasing substrate temperature the growth of material with an increasing concentration of voids. These data are corroborated by analysis of infrared absorption data in terms of microstructure parameters. For material of low substrate temperature (and high void concentration) tritium outgassing in air at room temperature was studied, and it was found that after 600 h about 0.2% of the total hydrogen (hydrogen+tritium) content is released. Two rate limiting processes are identified. The first process, fast tritium outgassing with a time constant of 15 h, seems to be related to surface desorption of tritiated water (HTO) with a free energy of desorption of 1.04 eV. The second process, slow tritium outgassing with a time constant of 200-300 h, appears to be limited by oxygen diffusivity in a growing oxide layer. This material of lowest H stability would lose half of the hydrogen after 60 years. © 2008 American Institute of Physics