A theoretical look at the direct detection of giant planets outside the Solar System

Astronomy is at times a science of unexpected discovery. When it is, and if we are lucky, new intellectual territories emerge to challenge our views of the cosmos. The recent indirect detections using high-precision Doppler spectroscopy of now more than one hundred giant planets orbiting more than one hundred nearby stars is an example of such rare serendipity. What has been learned has shaken our preconceptions, for none of the planetary systems discovered to date is like our own. However, the key to unlocking a planet's chemical, structural, and evolutionary secrets is the direct detection of the planet's light. I review the embryonic theory of the spectra, atmospheres, and light curves of irradiated giant planets and put this theory into the context of the many proposed astronomical campaigns to image them.Comment: pre-editorial, non-copyrighted version of Review Article just published in Nature. 5 figures, one in JPEG forma

Linking period and cohort life-expectancy linear increases in Gompertz proportional hazards models

In a Gompertz mortality model with constant yearly improvements at all ages, linear increases in period life expectancy correspond to linear increases in the respective cohort life expectancy. The link between the two measures can be given by a simple approximate relationship.cohort life expectancy, Gompertz mortality, Linear Shift Models, period life expectancy

Flavor and CP violating physics from new supersymmetric thresholds

Treating the MSSM as an effective theory, we study the implications of having dimension five operators in the superpotential for flavor and CP-violating processes, exploiting the linear decoupling of observable effects with respect to the new threshold scale \Lambda. We show that the assumption of weak scale supersymmetry, when combined with the stringent limits on electric dipole moments and lepton flavor-violating processes, provides sensitivity to \Lambda as high as 10^7-10^9 GeV, while the next generation of experiments could directly probe the high-energy scales suggested by neutrino physics.Comment: 4 pages, 1 figur

Hohenberg-Kohn theorem for the lowest-energy resonance of unbound systems

We show that under well-defined conditions the Hohenberg-Kohn theorem (HKT) can be extended to the lowest-energy resonance of unbound systems. Using the Gel'fand Levitan theorem, the extended version of the HKT can also be applied to systems that support a finite number of bound states. The extended version of the HKT provides an adequate framework to carry out DFT calculations of negative electron affinities.Comment: 4 pages, 3 figure

Discretised Non-Linear Filtering for Dynamic Latent Variable Models: with Application to Stochastic Volatility

Filtering techniques are often applied to the estimation of dynamic latent variable models. However, these techniques are often based on a set assumptions which restrict models to be specified in a linear state-space form. Numerical filtering techniques have been propsed that avoid invoking such restrictive assumptions, thus permitting a wider class of latent variable models to be considered. This paper proposes an accurate yet computationally efficient numerical filtering algorithm (based on a discretisation of the state space) for estimating the general class of dynamic latent variable models. The empirical performance of this algorithm is considered within the context of the stochastic volatility model. It is found that the proposed algorithm outperforms a number of accepted procedures in terms of volatility forecastiNon-linear filtering, latent variable models, stochastic volatility, volatilitry forecasting