We measure the effects of charge transfer efficiency (CTE) losses on resolved sources in Wide Field and Planetary Camera 2 (WFPC2) images from 1995 to 2008. We compare medium and long exposures of the Hubble Deep Field – North taken with the F606W filter at several epochs against a “truth” mosaic of the field taken with the Advanced Camera for Surveys early in that instrument’s operation. We ad...

The parameter estimates based on an econometric equation are biased and can also be inconsistent when relevant regressors are omitted from the equation or when included regressors are measured with error. This problem gets complicated when the ‘true’ functional form of the equation is unknown. Here, we demonstrate how auxiliary variables, called concomitants, can be used to remove omitted-varia...

Up until a few years ago, the dispersion parameter of Poisson-gamma models has been assumed to be invariant of the characteristics of the observations under study, but recent research in highway safety has shown that the dispersion parameter can potentially be dependent upon the covariates of the model. To account for this dependence, some researchers have reported that the dispersion parameter...

We propose a nonparametric varying coefficient method that admits both qualitative and quantitative regressors. The proposed estimator is exceedingly flexible and has a wide range of potential applications including hierarchical (mixed) settings, small area estimation, and so forth. For example, the method provides for semiparametric models in which practitioners can select a parametric functio...

In this paper we give necessary and sufficient conditions under which kernels of dot product type k(x, y) = k(x · y) satisfy Mercer’s condition and thus may be used in Support Vector Machines (SVM), Regularization Networks (RN) or Gaussian Processes (GP). In particular, we show that if the kernel is analytic (i.e. can be expanded in a Taylor series), all expansion coefficients have to be nonneg...

We analyze the structure of noncommutative pure Chern-Simons theory systematically in the axial gauge. We show that there is no IR/UV mixing in this theory in this gauge. In fact, we show, using the usual BRST identities as well as the identities following from vector supersymmetry, that this is a free theory. As a result, the tree level Chern-Simons coefficient is not renormalized. It also hol...

In this paper I propose new continuous and discrete choice demand models. To do so, I note that existing demand models from the continuousand discrete-choice demand literatures each have distinct advantages for taking to market-level data. I attempt to build models with the union of the good properties of each literature. For instance, the continuous choice models are more appropriate for disag...

The solution of many physical evolution equations can be expressed as an exponential of two or more operators acting on initial data. Accurate solutions can be systematically derived by decomposing the exponential in a product form. For time-reversible equations, such as the Hamilton or the Schrödinger equation, it is immaterial whether or not the decomposition coefficients are positive. In fac...