Statistical eigen-inference from large Wishart matrices

We consider settings where the observations are drawn from a zero-mean multivariate (real or complex) normal distribution with the population covariance matrix having eigenvalues of arbitrary multiplicity. We assume that the eigenvectors of the population covariance matrix are unknown and focus on inferential procedures that are based on the sample eigenvalues alone (i.e., "eigen-inference"). Results found in the literature establish the asymptotic normality of the fluctuation in the trace of powers of the sample covariance matrix. We develop concrete algorithms for analytically computing the limiting quantities and the covariance of the fluctuations. We exploit the asymptotic normality of the trace of powers of the sample covariance matrix to develop eigenvalue-based procedures for testing and estimation. Specifically, we formulate a simple test of hypotheses for the population eigenvalues and a technique for estimating the population eigenvalues in settings where the cumulative distribution function of the (nonrandom) population eigenvalues has a staircase structure. Monte Carlo simulations are used to demonstrate the superiority of the proposed methodologies over classical techniques and the robustness of the proposed techniques in high-dimensional, (relatively) small sample size settings. The improved performance results from the fact that the proposed inference procedures are "global" (in a sense that we describe) and exploit "global" information thereby overcoming the inherent biases that cripple classical inference procedures which are "local" and rely on "local" information.Comment: Published in at http://dx.doi.org/10.1214/07-AOS583 the Annals of Statistics (http://www.imstat.org/aos/) by the Institute of Mathematical Statistics (http://www.imstat.org

The Use of Compensation With Directional Couplers

This thesis describes an improved technique for measuring voltage standing wave ratio (VSWR). The reflectometer system is analyzed, and an improved coaxial system is presented which more accurately measures VSWR

Participation in continuing vocational education and training: results from the case studies and qualitative investigations

Contents: Introduction; Germany; Greece; Italy; Portugal; Spain; United Kingdo

CIRCUIT AND CONTAINMENT ASPECTS OF PHÉBUS EXPERIMENTS FPT0 AND FPT1

The Phebus FP severe accident experiments FPT0 and FPT1 were performed at Institut de radioprotection et de sûreté nucléaire (IRSN, Radioprotection and Nuclear Safety Institute) Cadarache (France) in 1993 and 1996 respectively. In each test a 1 m long bundle of fuel rods plus a silver indium cadmium control rod was heated to an advanced state of degradation in the Phebus reactor, and the materials released were swept by an injected steam flow through a model circuit and into a miniature containment vessel. Test FPT0 used fresh fuel, while in FPT1 the fuel had a burnup of 23 GWd/tonne. In an international effort coordinated by the European Commission Joint Research Centre and IRSN intensive analytical study of data from the circuit and containment was performed using a variety of models and computer codes, seeking to reconcile the wide variety and copious quantity of online and post-test data available and to draw conclusions. The present consolidation report makes a critical survey of the degree of success achieved and draws conclusions as to where understanding can be considered good and where it appears necessary to perform further analytical work, factoring in both findings from other tests of the Phebus FP series and from other experimental programmes.JRC.F.5-Nuclear Reactor Safety Assessmen

Prospective Minority Students\u27 Perceptions of Application Packets for Professional Psychology Programs: A Qualitative Study

This article reports the results of a qualitative study designed to determine issues salient in Black and Hispanic American students\u27 review and evaluation of program-application packets in professional psychology. The study served as an extension to the Yoshida et al. (1989) quantitative investigation. Students interested in pursuing doctoral studies in counseling or school psychology (N = 22) served as the sample. The qualitative methodology incorporated a think-aloud procedure and semistructured interviews. A theme analysis of transcribed interviews identified both major and minor themes central to participants\u27 evaluation of the packets. Major themes included financial aid, program requirements and course descriptions, demography of the student body, and the quality and clarity of application material. Specific suggestions on developing an application packet to send to inquiring prospective students are put forth. It is recommended that such a packet could serve as a cost-effective minority-recruitment strategy

Minority Student Perceptions of Professional Pscyhology Application Packets: A Qualitative Study

This article reports the results of a qualitative study designed to determine issues salient in Black and Hispanic American students\u27 review and evaluation of program-application packets in professional psychology. The study served as an extension to the Yoshida et al. (1989) quantitative investigation. Students interested in pursuing doctoral studies in counseling or school psychology (N = 22) served as the sample. The qualitative methodology incorporated a think-aloud procedure and semistructured interviews. A theme analysis of transcribed interviews identified both major and minor themes central to participants\u27 evaluation of the packets. Major themes included financial aid, program requirements and course descriptions, demography of the student body, and the quality and clarity of application material. Specific suggestions on developing an application packet to send to inquiring prospective students are put forth. It is recommended that such a packet could serve as a costeffective minority-recruitment strategy

ADOPTION OF SUPPLEMENTAL WORK-AT-HOME: A COMPARATIVE ANALYSIS

The primary purpose of this study is to develop a deeper understanding of the dynamics of the adoption of SWAH. Specifically, it examines how the work and family environments of dual-career male and female and traditional male parents who perform SWAH differ from the work and family environments of their cohorts who do not. People who perform SWAH were found to work significantly more hours per week and more hours at home than those who did not adopt SWAH. The data indicates that men and women who have higher level more challenging jobs (Le., greater work expectations and lower role clarity) were more likely to adopt SWAH than were men and women with fewer career demands. There were no significant differences in the family environments of men who did and did not adopt SWAH. Perceived family responsibility (i.e., family involvement, family expectations) was associated with a woman\u27s tendency to adopt SWAH

Rapid Targeted Gene Disruption in Bacillus Anthracis

Anthrax is a zoonotic disease recognized to affect herbivores since Biblical times and has the widest range of susceptible host species of any known pathogen. The ease with which the bacterium can be weaponized and its recent deliberate use as an agent of terror, have highlighted the importance of gaining a deeper understanding and effective countermeasures for this important pathogen. High quality sequence data has opened the possibility of systematic dissection of how genes distributed on both the bacterial chromosome and associated plasmids have made it such a successful pathogen. However, low transformation efficiency and relatively few genetic tools for chromosomal manipulation have hampered full interrogation of its genome. Results: Group II introns have been developed into an efficient tool for site-specific gene inactivation in several organisms. We have adapted group II intron targeting technology for application in Bacillus anthracis and generated vectors that permit gene inactivation through group II intron insertion. The vectors developed permit screening for the desired insertion through PCR or direct selection of intron insertions using a selection scheme that activates a kanamycin resistance marker upon successful intron insertion. Conclusions: The design and vector construction described here provides a useful tool for high throughput experimental interrogation of the Bacillus anthracis genome and will benefit efforts to develop improved vaccines and therapeutics.Chem-Bio Diagnostics program from the Department of Defense Chemical and Biological Defense program through the Defense Threat Reduction Agency (DTRA) B102387MNIH GM037949Welch Foundation F-1607Cellular and Molecular Biolog

Level spacing statistics for the multi-dimensional quantum harmonic oscillator: Algebraic case

We study the statistical properties of the spacings between neighboring energy levels for the multi-dimensional quantum harmonic oscillator that occur in a window [E, E + ΔE) of fixed width ΔE as E tends to infinity. This regime provides a notable exception to the Berry–Tabor conjecture from quantum chaos, and, for that reason, it was studied extensively by Berry and Tabor in their seminal paper from 1977. We focus entirely on the case that the (ratios of) frequencies ω1, ω2, …, ωd together with 1 form a basis for an algebraic number field Φ of degree d + 1, allowing us to use tools from algebraic number theory. This special case was studied by Dyson, Bleher, Bleher–Homma–Ji–Roeder–Shen, and others. Under a suitable rescaling, we prove that the distribution of spacings behaves asymptotically quasiperiodically in log E. We also prove that the distribution of ratios of neighboring spacings behaves asymptotically quasiperiodically in log E. The same holds for the distribution of finite words in the finite alphabet of rescaled spacings. Mathematically, our work is a higher dimensional version of the Steinhaus conjecture (three gap theorem) involving the fractional parts of a linear form in more than one variable, and it is of independent interest from this perspective