An example and some questions fo Bayesian nonparametric statistics, from a predictive point of view

In this note we raise some questions for Bayesian nonparametric statistics starting from an example. The problems is described by Coram an Diaconis (2001) and regards studying, by probabilistic techniques, the correspondence between the eigenvalues of random unitary matrices and the complex zeros of Riemann's zeta function. This is an intriguing problem, and we will only underline some of the questions which might arise if we look at it from a (non parametric) Bayesian point of view.

State Space Models in R

We give an overview of some of the software tools available in R, either as built- in functions or contributed packages, for the analysis of state space models. Several illustrative examples are included, covering constant and time-varying models for both univariate and multivariate time series. Maximum likelihood and Bayesian methods to obtain parameter estimates are considered.

Bayes and empirical Bayes: do they merge?

Bayesian inference is attractive for its coherence and good frequentist properties. However, it is a common experience that eliciting a honest prior may be difficult and, in practice, people often take an {\em empirical Bayes} approach, plugging empirical estimates of the prior hyperparameters into the posterior distribution. Even if not rigorously justified, the underlying idea is that, when the sample size is large, empirical Bayes leads to "similar" inferential answers. Yet, precise mathematical results seem to be missing. In this work, we give a more rigorous justification in terms of merging of Bayes and empirical Bayes posterior distributions. We consider two notions of merging: Bayesian weak merging and frequentist merging in total variation. Since weak merging is related to consistency, we provide sufficient conditions for consistency of empirical Bayes posteriors. Also, we show that, under regularity conditions, the empirical Bayes procedure asymptotically selects the value of the hyperparameter for which the prior mostly favors the "truth". Examples include empirical Bayes density estimation with Dirichlet process mixtures.Comment: 27 page

Two Boats, Three Summers, Five Universities, One Dozen Instructors, and Sixty-Five Teachers: A Collaborative Oceanography Field Program for Earth Science

A three-day field workshop was an integral component of the graduate-level course entitled, Oceanography, that was offered by Virginia Earth Science Collaborative Project (VESC) to help Virginia educators earn the earth science teaching endorsement. The VESC partner institutions that offered Oceanographngeorge Mason University, James Madison University, the University of Virginia Southwest Center, and Virginia Commonwealth University-lacked direct access to research and education facilities en the coast. The College of William & Mary, another VESC partner, provided this resource through the Virginia Institute of Marine Science’s (VIMS) Eastern Shore Laboratory in Wachapreague, Virginia. The field program agenda and activities were developed and conducted by a team comprised of VESC oceanography faculty, Virginia Sea Grant educators, and a scientist from VIMS. This collaboration resulted in a program design used as the basis for six workshops conducted over three summers. Seventy-nine Virginia middle school and high school science teachers took part in the six workshops, conducted in July of 2005, 2006, and 2007. This article describes the workshop activities and provides perspectives on its design and implementation from the viewpoints of Virginia Sea Grant educators who served as field instructors

Vanadium redox flow batteries: Potentials and challenges of an emerging storage technology

open4noIn this paper an overview of Vanadium Redox Flow Battery technologies, architectures, applications and power electronic interfaces is given. These systems show promising features for energy storage in smart grid applications, where the intermittent power produced by renewable sources must meet strict load requests and economical opportunities. This paper reviews the vanadium-based technology for redox flow batteries and highlights its strengths and weaknesses, outlining the research lines that aim at taking it to full commercial success.openSpagnuolo, Giovanni, Guarnieri, Massimo; Mattavelli, Paolo; Petrone, Giovanni;Guarnieri, Massimo; Mattavelli, Paolo; Petrone, Giovanni; Spagnuolo, Giovann