A J-Spectral Factorization Approach to ℋ∞ Control

Necessary and sufficient conditions for the existence of suboptimal solutions to the standard model matching problem associated with ℋ∞ control, are derived using J-spectral factorization theory. The existence of solutions to the model matching problem is shown to be equivalent to the existence of solutions to two coupled J-spectral factorization problems, with the second factor providing a parametrization of all solutions to the model matching problem. The existence of the J-spectral factors is then shown to be equivalent to the existence of nonnegative definite, stabilizing solutions to two indefinite algebraic Riccati equations, allowing a state-space formula for a linear fractional representation of all controllers to be given. A virtue of the approach is that a very general class of problems may be tackled within a conceptually simple framework, and no additional auxiliary Riccati equations are required

Neandertal Craniofacial Growth: An Ontogenetic Model

This research seeks to develop a model, using modern fetal crania, of Neandertal craniofacial growth. An argument is made that the developmental approach offers greater insight into Neandertal adaptive morphology than the standard functional models. Discussion of the relation between allometry and heterochrony is followed by a general genetic overview and a description of modern fetal craniofacial growth. These patterns are then extrapolated to the Neandertal condition. Samples for this work consist of modern fetal crania, three modern adult samples, one sample of early modern humans and a sample of Neandertal adults. Principle components analysis was utilized, as was least squares and reduced major axis regressions. A technique was devised where derivatives were taken from polynomials generated from multiple regression. The results would indicate that the posterior cranial base, and not the anterior base, has the neural like growth pattern. The anterior base has a growth pattern similar to that of facial length and facial height. Using pattern of morphogenesis and known principles of cartilage kinetics, a model of Neandertal craniofacial growth was created. Emphasis was placed upon the effects of global growth acceleration on synchrondrosal cartilage dynamics and the resulting relation of base flexure to facial projection. It was concluded that many features of the Neandertal cranium and face are the byproduct of selection for rapid growth rate. It is also concluded that these effects need not imply species level genetic differences. In fact, tests using least squares and reduced major axis regression imply that early modern Europeans had growth rates intermediate between Neandertals and modern blacks. This result is consistent with Assimilation models and inconsistent with the Total Replacement models

Breaking the cycle? The effect of education on welfare receipt among children of welfare recipients

We examine the impact of high school graduation on the probability individuals from welfare backgrounds use welfare themselves. Our data consists of administrative educational records for grade 12 students in a Canadian province linked with their own and their parents' welfare records. We address potential endogeneity problems by: 1) controlling for ability using past test scores; 2) using an instrument for graduation based on school principal fixed effects; and 3) using a Heckman- Singer type unobserved heterogeneity estimator. Graduation would reduce welfare receipt of dropoutsby Ý to 3/4. Effects are larger for individuals from troubled family backgrounds and low income neighbourhoods.

Consortium and Workers’ Compensation: The Demolition of Consortium

The article discusses issues on spousal consortium claims and workers\u27 compensation in the U.S., including the aspects of compensation for accidental injuries and tort claims

A Confirmatory Factor Analysis of Two Web Site Usability Instruments

Many perspectives of user acceptance of Web sites have been examined, yet information systems research often overlooks the human-computer interaction aspects, particularly in the area of Web site usability. Web site usability has recently gained greater acceptance in information literature through the development of instruments by Palmer (2002) and Agarwal and Venkatesh (2002). This study conducted a confirmatory factor analysis of both instruments in an attempt to validate the two instruments. Our results found that the Palmer instrument exhibited satisfactory measurement properties, although allowing room for further refinement. The Agarwal and Venkatesh instrument, although useful as a practical metric, displayed poor validity for the underlying constructs that compose Web site usability. Validation of these instruments furthers their scope and potential use by researchers and practitioners in helping them better understand the capabilities of their Web sites, while providing a foundation for further refinement of the Web site usability construct

The Relationship between Cost Analysis and Program Management

Cost analysis if often viewed as applying basic principles and cost methodologies to determine total system cost. These finished estimates then flow into a decision making process and the cost estimator leaves the stage. Reality shows that the cost estimator is actually one of the main contributors to the decision making process. Our introduction to this special issue explores the areas where cost estimating plays a major role in program management in areas beyond the normal program estimate. We have included articles that show the key role estimators can play in source selection strategies and evaluation; cost of delay analysis for management decisions, earned value management methods to predict program costs; decision criteria to rank competing projects that complement traditional cost-based methods; and a new methodology for determining research and development budget profiles

Human transcription factor YY1 represses human immunodeficiency virus type 1 transcription and virion production

The transcriptional activity of human immunodeficiency virus type 1 (HIV-1) is affected by many cellular factors. Homologies near the HIV-1 initiator region to the DNA-binding sequences of YY1, a multifunctional transcription factor known to regulate diverse viral and cellular promoters, suggested that YY1 might regulate HIV-1. Antibody to YY1 blocked the formation of complexes by HeLa cell nuclear extract and a DNA oligonucleotide encoding the HIV-1 initiator region. HIV-1 long terminal repeat (LTR) expression, as measured the expression of a transfected LTR-CAT reporter gene, was repressed more than 12-fold by the cotransfection of a YY1 expression vector. HIV-1 production by both COS-1 and CEM cells after transfection of an infectious molecular HIV-1 clone was repressed 7- to 20-fold by cotransfection of a YY1 expression vector. HIV-1 production was also decreased threefold in a CD4-positive lymphocyte cell line chronically infected with HIV-1 (8E5) after transfection of YY1. In situ hybridization studies confirmed that YY1 reduced HIV-1 RNA expression. YY1 may play an important role in the regulation of HIV-1 LTR expression in vivo and virus production by infected cells

Measurement of the cosmic-ray proton spectrum from 54 GeV to 9.5 TeV with the Fermi Large Area Telescope

Cosmic rays are a near-isotropic continuous flux of energetic particles of extraterrestrial origin. First discovered in 1912, cosmic rays span over 10 decades of energy and originate from Galactic and extragalactic sources. The Fermi Gamma-ray Space Telescope observations have recently confirmed supernova remnants (SNR) as a source class for Galactic cosmic-ray protons. Additionally, recent measurements made by AMS-02 of the cosmic-ray proton spectrum to 1.8 TeV in kinetic energy have shown an unexpected spectral break at 415 ± 117 GeV with a primary spectral index of −2.794±0.006 and a secondary spectral index of −2.702±0.047. The Fermi Large Area Telescope (LAT), one of two instruments on Fermi, has an ideal energy range for confirming a spectral break and extending a space-based cosmic-ray proton spectrum measurement to overlap with higher energy balloon-borne measurements. In this thesis, I present the measurement of the cosmic-ray proton spectrum from 54 GeV to 9.5 TeV with the Fermi-LAT. Using the LAT’s anti-coincidence detector and tracker as two independent measures of charge, I estimated a residual contamination in our proton data set of less than 5% primarily from cosmic-ray electrons and positrons. The LAT calorimeter provides an energy estimation of the electromagnetic fraction of an induced cosmic-ray proton shower. I use the charge and energy measurements to build instrument response functions, such as acceptance and response for the LAT, and measure cosmic-ray proton flux. I estimate the systematic uncertainties associated with the acceptance and the energy measurement. Using a broken power-law spectrum, I find a primary spectral index of −2.80 ± 0.03, a secondary spectral index of −2.60 ± 0.04, and an energy break of 467 ± 144 GeV. I discuss possible astrophysical and cosmic-ray physics interpretations for the observed spectral break

Roof Loads for Reliability Analysis of Lumber Properties Data

With load information reported in previous studies, distributions of maximum lifetime roof loads are developed in a form suitable for use in reliability analyses of lumber properties data. A lognormal distribution is chosen as best representing normalized maximum lifetime roof snow load.Examples are given in which contrasting lumber data sets are compared using the calculated load distributions and assuming that each set must provide equal reliability (equal safety) in the final design. A factor, k, resulting from this reliability analysis is shown to be a logical adjustment parameter for use in engineering design codes