CMB Isotropy Anomalies and the Local Kinetic Sunyaev-Zel'dovich Effect

Several anomalies have been identified which may imply a breakdown of the statistical isotropy of the cosmic microwave background (CMB). In particular, an anomalous alignment of the quadrupole and octopole and a hemispherical power asymmetry have increased in significance as the data have improved. There have been several attempts to explain these observations which explore isotropy breaking mechanisms within the early universe, but little attention has been given to the possibility that these anomalies have their origin within the local universe. We explore such a mechanism by considering the kinetic Sunyaev-Zel'dovich effect due to a gaseous halo associated with the Milky Way. Considering several physical models of an anisotropic free electron optical depth contributed by such a halo, we find that the associated screening maps of the primordial anisotropies have the necessary orientations to affect the anomaly statistics very significantly, but only if the column density of free electrons in the halo is at least an order of magnitude higher than indicated by current observations.Comment: 10 pages, 4 figure

Optimal filters for detecting cosmic bubble collisions

A number of well-motivated extensions of the LCDM concordance cosmological model postulate the existence of a population of sources embedded in the cosmic microwave background (CMB). One such example is the signature of cosmic bubble collisions which arise in models of eternal inflation. The most unambiguous way to test these scenarios is to evaluate the full posterior probability distribution of the global parameters defining the theory; however, a direct evaluation is computationally impractical on large datasets, such as those obtained by the Wilkinson Microwave Anisotropy Probe (WMAP) and Planck. A method to approximate the full posterior has been developed recently, which requires as an input a set of candidate sources which are most likely to give the largest contribution to the likelihood. In this article, we present an improved algorithm for detecting candidate sources using optimal filters, and apply it to detect candidate bubble collision signatures in WMAP 7-year observations. We show both theoretically and through simulations that this algorithm provides an enhancement in sensitivity over previous methods by a factor of approximately two. Moreover, no other filter-based approach can provide a superior enhancement of these signatures. Applying our algorithm to WMAP 7-year observations, we detect eight new candidate bubble collision signatures for follow-up analysis.Comment: 12 pages, 6 figures, replaced to match version accepted by PR

Strong Lensing Probabilities in a Cosmological Model with a Running Primordial Power Spectrum

The combination of the first-year Wilkinson Microwave Anisotropy Probe (WMAP) data with other finer scale cosmic microwave background (CMB) experiments (CBI and ACBAR) and two structure formation measurements (2dFGRS and Lyman $\alpha$ forest) suggest a $\Lambda$CDM cosmological model with a running spectral power index of primordial density fluctuations. Motivated by this new result on the index of primordial power spectrum, we present the first study on the predicted lensing probabilities of image separation in a spatially flat $\Lambda$CDM model with a running spectral index (RSI-$\Lambda$CDM model). It is shown that the RSI-$\Lambda$CDM model suppress the predicted lensing probabilities on small splitting angles of less than about 4$^{''}$ compared with that of standard power-law $\Lambda$CDM (PL-$\Lambda$CDM) model.Comment: 11 pages including 1 figures. Accepted for publication in Modern Physics Letters A (MPLA), minor revision

Estimating and Forecasting Generalized Fractional Long Memory Stochastic Volatility Models

In recent years fractionally differenced processes have received a great deal of attention due to its flexibility in financial applications with long memory. This paper considers a class of models generated by Gegenbauer polynomials, incorporating the long memory in stochastic volatility (SV) components in order to develop the General Long Memory SV (GLMSV) model. We examine the statistical properties of the new model, suggest using the spectral likelihood estimation for long memory processes, and investigate the finite sample properties via Monte Carlo experiments. We apply the model to three exchange rate return series. Overall, the results of the out-of-sample forecasts show the adequacy of the new GLMSV model

Primordial Black Holes, Eternal Inflation, and the Inflationary Parameter Space after WMAP5

We consider constraints on inflation driven by a single, minimally coupled scalar field in the light of the WMAP5 dataset, as well as ACBAR and the SuperNova Legacy Survey. We use the Slow Roll Reconstruction algorithm to derive optimal constraints on the inflationary parameter space. The scale dependence in the slope of the scalar spectrum permitted by WMAP5 is large enough to lead to viable models where the small scale perturbations have a substantial amplitude when extrapolated to the end of inflation. We find that excluding parameter values which would cause the overproduction of primordial black holes or even the onset of eternal inflation leads to potentially significant constraints on the slow roll parameters. Finally, we present a more sophisticated approach to including priors based on the total duration of inflation, and discuss the resulting restrictions on the inflationary parameter space.Comment: v2: version published in JCAP. Minor clarifications and references adde

Economic Value of Climate Variability Impacts on Coconut Production in Sri Lanka

This paper assesses the economic value of climate variability, employing a percentile analysis on an array of 31-years national annual coconut production data from 1971 to 2001. Of the production array, 10% and 90% percentiles have been considered respectively as lower and upper production extremes. The 60% of production departures of each year of extremes with respect to the mean production of 10% to 90% percentile were attributed to climate variability because studies show that the 60% of the variation of coconut production is explained by climate. These production deviations were then valued multiplying by free-on-board (FOB) prices of fresh coconuts. Results show that the foregone income from coconuts due to low rainfall varied between US$32 million to US$ 73 million while the incremental coconut income in crop glut extremes due to high rainfall varied between US$42 million and US$ 87 million. Results show that the climate variability causes income losses to the economy estimated at US$32 million to US$ 73 million in years of extreme crop shortage. And in years of extreme crop surplus, the economy realises income gains of US$42 million to US$ 87 million. These indicate the potential for significant economic benefits from investments in adaptations that would reduce variability in nut production which is caused by variations in climate. Further work is however needed to estimate the effectiveness and economic benefits that might be achieved from investments in adaptation

Viral evolution from one generation of human influenza infection to the next

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Viral shedding, clinical history and transmission of influenza

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