How exactly did the Universe become neutral?

We present a refined treatment of H, He I, and He II recombination in the early Universe. The difference from previous calculations is that we use multi-level atoms and evolve the population of each level with redshift by including all bound-bound and bound-free transitions. In this framework we follow several hundred atomic energy levels for H, He I, and He II combined. The main improvements of this method over previous recombination calculations are: (1) allowing excited atomic level populations to depart from an equilibrium distribution; (2) replacing the total recombination coefficient with recombination to and photoionization from each level directly at each redshift step; and (3) correct treatment of the He I atom, including the triplet and singlet states. We find that the ionization fraction x_e = n_e/n_H is approximately 10% smaller at redshifts <~800 than in previous calculations, due to the non-equilibrium of the excited states of H, which is caused by the strong but cool radiation field at those redshifts. In addition we find that He I recombination is delayed compared with previous calculations, and occurs only just before H recombination. These changes in turn can affect the predicted power spectrum of microwave anisotropies at the few percent level. Other improvements such as including molecular and ionic species of H, including complete heating and cooling terms for the evolution of the matter temperature, including collisional rates, and including feedback of the secondary spectral distortions on the radiation field, produce negligible change to x_e. The lower x_e at low z found in this work affects the abundances of H molecular and ionic species by 10-25%. However this difference is probably not larger than other uncertainties in the reaction rates.Comment: 24 pages, including 18 figures, using emulateapj.sty, to appear in ApJ, the code recfast can be obtained at http://www.astro.ubc.ca/people/scott/recfast.html (in FORTRAN) and http://cfa-www.harvard.edu/~sasselov/rec/ (in C

Cryopyrin-Associated Periodic Syndrome: An Update on Diagnosis and Treatment Response

Cryopyrin-associated periodic syndrome (CAPS) is a rare hereditary inflammatory disorder encompassing a continuum of three phenotypes: familial cold autoinflammatory syndrome, Muckle-Wells syndrome, and neonatal-onset multisystem inflammatory disease. Distinguishing features include cutaneous, neurological, ophthalmologic, and rheumatologic manifestations. CAPS results from a gain-of-function mutation of the NLRP3 gene coding for cryopyrin, which forms intracellular protein complexes known as inflammasomes. Defects of the inflammasomes lead to overproduction of interleukin-1, resulting in inflammatory symptoms seen in CAPS. Diagnosis is often delayed and requires a thorough review of clinical symptoms. Remarkable advances in our understanding of the genetics and the molecular pathway that is responsible for the clinical phenotype of CAPS has led to the development of effective treatments. It also has become clear that the NLRP3 inflammasome plays a critical role in innate immune defense and therefore has wider implications for other inflammatory disease states

Predicting quarterly Hong Kong tourism demand growth rates, directional changes and turning points with composite leading indicators

This study predicts numerical demand growth rates, directional changes and turning points in the growth rate using the single input leading indicator model and assesses its forecasting performance with the ARIMA model and the no-change model. To assess the forecasting performance from the March quarter of 2004 to the December quarter of 2006, models are fitted to the growth rates of Hong Kong inbound tourism demand from selected tourism markets (Australia, Japan, the UK and the USA). Composite leading indicators for the single input leading indicator model are constructed from selected national leading and lagged indicators. To avoid false signals in turning points, a method is specified to identify the correct turning points in tourism demand growth rates. The prediction performance of these models is then examined, based on the mean absolute percentage error, directional change error and turning point error. A statistical procedure is considered to determine whether the actual and predicted directional changes and turning points are independent or associated

Will business cycles in the euro area converge? A critical survey of empirical research

This survey of business cycle synchronization in the European monetary union focuses on two issues: have business cycles become more similar, and which factors drive business cycle synchronization. We conclude that business cycles in the euro area have gone through periods of both convergence and divergence. Still, there is quite some evidence that during the 1990s business cycle synchronization in the euro area has increased. Higher trade intensity is found to lead to more synchronization, but the point estimates vary widely. The evidence for other factors affecting business cycle synchronization is very mixed