Poisson Latent Feature Calculus for Generalized Indian Buffet Processes

The purpose of this work is to describe a unified, and indeed simple, mechanism for non-parametric Bayesian analysis, construction and generative sampling of a large class of latent feature models which one can describe as generalized notions of Indian Buffet Processes(IBP). This is done via the Poisson Process Calculus as it now relates to latent feature models. The IBP was ingeniously devised by Griffiths and Ghahramani in (2005) and its generative scheme is cast in terms of customers entering sequentially an Indian Buffet restaurant and selecting previously sampled dishes as well as new dishes. In this metaphor dishes corresponds to latent features, attributes, preferences shared by individuals. The IBP, and its generalizations, represent an exciting class of models well suited to handle high dimensional statistical problems now common in this information age. The IBP is based on the usage of conditionally independent Bernoulli random variables, coupled with completely random measures acting as Bayesian priors, that are used to create sparse binary matrices. This Bayesian non-parametric view was a key insight due to Thibaux and Jordan (2007). One way to think of generalizations is to to use more general random variables. Of note in the current literature are models employing Poisson and Negative-Binomial random variables. However, unlike their closely related counterparts, generalized Chinese restaurant processes, the ability to analyze IBP models in a systematic and general manner is not yet available. The limitations are both in terms of knowledge about the effects of different priors and in terms of models based on a wider choice of random variables. This work will not only provide a thorough description of the properties of existing models but also provide a simple template to devise and analyze new models.Comment: This version provides more details for the multivariate extensions in section 5. We highlight the case of a simple multinomial distribution and showcase a multivariate Levy process prior we call a stable-Beta Dirichlet process. Section 4.1.1 expande

EMS control system design for a Maglev vehicle - a critical system

For the effective operation of a magnetically levitated (maglev) vehicle using electro-magnetic suspension, it is necessary that the airgap between the guideway and the levitating magnets is maintained. Such systems, where the output is required to remain strictly within bounds, are known as critical systems. This paper describes the design of the suspension system for a high-speed maglev vehicle which ensures that the airgap is maintained

Velocity correlations and the structure of nonequilibrium hard core fluids

A model for the pair distribution function of nonequilibrium hard-core fluids is proposed based on a model for the effect of velocity correlations on the structure. Good agreement is found with molecular dynamics simulations of granular fluids and of sheared elastic hard spheres. It is argued that the incorporation of velocity correlations are crucial to correctly modeling atomic scale structure in nonequilibrium fluids.Comment: Final corrections after referees' reports. To appear in PR

Nuclear spin--rotation interaction in the hydrogen molecular ion

The nuclear spin--rotation interaction in the hyperfine structure of the hydrogen molecular ion is investigated. The interaction constants are determined and are found to differ in sign and magnitude compared to another theory, but they are in agreement with some values derived from experiment.Comment: RevTeX, 8 pages, no figure

Learning from Jesus’ Wife: What Does Forgery Have to Do with the Digital Humanities?

McGrath’s chapter on the so-called Gospel of Jesus’ Wife sets aside as settled the question of the papyrus’ authenticity, and explores instead what we can learn about the Digital Humanities and scholarly interaction in a digital era from the way the discussions and investigations of that work unfolded, and how issues that arose were handled. As news of purported new finds can spread around the globe instantaneously facilitated by current technology and social media, how can academics utilize similar technology to evaluate authenticity, but even more importantly, inform the broader public about the importance of provenance, and the need for skepticism towards finds that appear via the antiquities market