We extend the concept of the ridgeline from Ray and Lindsay (2005) to finite mixtures of general elliptical densities with possibly distinct density generators in each component. This can be used to obtain bounds for the number of modes of two-component mixtures of t distributions in any dimension. In case of proportional dispersion matrices, these have at most three modes, while for equal degr...

The Advanced Identity Representation (AIR) Project is a new interdisciplinary approach to the problem of designing identity technologies to enable imaginative selfrepresentations for users by implementing dynamic social identity models grounded in computing and cognitive science. AIR Project research develops models of social computational identity (e.g., characters, avatars, and social network...

−− A simplified approach is presented to the transient atmospheric dispersion of accidental releases of natural gas, originated by leakages in pressurized ducts on sea level. In this scenario, shutoff valves are used for instantaneous shutdown of tube operation, isolating the harmful inventory, whose transient release is simulated providing estimations of gas instantaneous atmospheric concentra...

A Monte Carlo algorithm is iteratively run to identify candidate sources for atmospheric releases. The values of the ground measurements of concentration are synthetically generated by a benchmark simulation of a Gaussian dispersion model. At each iteration, a Gaussian reflected plume model is applied to compute the dispersion from a candidate source, and the resulting concentrations are compar...

Our multiscale air quality modeling activities are reviewed. Two different techniques, static grid nesting and dynamic grid adaptions are discussed. The mass conservation and transportive properties of our grid nesting technique are shown in a linear advection problem. Results from an air quality application to the northeastern U.S. are also presented. The solution accuracy with the adaptive gr...

OCTOBER 2004 AMERICAN METEOROLOGICAL SOCIETY | he data supporting aerosol research can be obtained either observationally or indirectly from models. Observations can be broadly divided into routine monitoring efforts, which may be used to continuously evaluate an assimilation model, or episodically generated data, localized in space and/or time (Fig. 1). Assimilated monitoring results, if they ...

In a recent paper, Peláez and Ynduráin evaluate some of the low energy observables of ππ scattering and obtain flat disagreement with our earlier results. The authors work with unsubtracted dispersion relations, so that their results are very sensitive to the poorly known high energy behaviour of the scattering amplitude. They claim that the asymptotic representation we used is incorrect and pr...

Fork-join and split-merge queueing systems are well-known abstractions of parallel systems in which each incoming task splits into subtasks that are processed by a set of parallel servers. A task exits the system when all of its subtasks have completed service. Two key metrics of interest in such systems are task response time and subtask dispersion. This paper presents a technique applicable t...