Research on the control of large space structures

The research effort on the control of large space structures at the University of Houston has concentrated on the mathematical theory of finite-element models; identification of the mass, damping, and stiffness matrix; assignment of damping to structures; and decoupling of structure dynamics. The objective of the work has been and will continue to be the development of efficient numerical algorithms for analysis, control, and identification of large space structures. The major consideration in the development of the algorithms has been the large number of equations that must be handled by the algorithm as well as sensitivity of the algorithms to numerical errors

Advanced engine study program

A design and analysis study was conducted to provide advanced engine descriptions and parametric data for space transfer vehicles. The study was based on an advanced oxygen/hydrogen engine in the 7,500 to 50,000 lbf thrust range. Emphasis was placed on defining requirements for high-performance engines capable of achieving reliable and versatile operation in a space environment. Four variations on the expander cycle were compared, and the advantages and disadvantages of each were assessed. Parametric weight, envelope, and performance data were generated over a range of 7,500 to 50,000 lb thrust and a wide range of chamber pressure and nozzle expansion ratio

Chaotic advection of reacting substances: Plankton dynamics on a meandering jet

We study the spatial patterns formed by interacting populations or reacting chemicals under the influence of chaotic flows. In particular, we have considered a three-component model of plankton dynamics advected by a meandering jet. We report general results, stressing the existence of a smooth-filamental transition in the concentration patterns depending on the relative strength of the stirring by the chaotic flow and the relaxation properties of planktonic dynamical system. Patterns obtained in open and closed flows are compared.Comment: 5 pages, 3 figues, latex compiled with modegs.cl

Functional gene analysis suggests different acetogen populations in the Bovine Rumen and Tammar Wallaby Forestomach

Reductive acetogenesis via the acetyl coenzyme A (acetyl-CoA) pathway is an alternative hydrogen sink to methanogenesis in the rumen. Functional gene-based analysis is the ideal approach for investigating organisms capable of this metabolism (acetogens). However, existing tools targeting the formyltetrahydrofolate synthetase gene (fhs) are compromised by lack of specificity due to the involvement of formyltetrahydrofolate synthetase (FTHFS) in other pathways. Acetyl-CoA synthase (ACS) is unique to the acetyl-CoA pathway and, in the present study, acetyl-CoA synthase genes (acsB) were recovered from a range of acetogens to facilitate the design of acsB-specific PCR primers. fhs and acsB libraries were used to examine acetogen diversity in the bovine rumen and forestomach of the tammar wallaby (Macropus eugenii), a native Australian marsupial demonstrating foregut fermentation analogous to rumen fermentation but resulting in lower methane emissions. Novel, deduced amino acid sequences of acsB and fhs affiliated with the Lachnospiraceae in both ecosystems and the Ruminococcaeae/Blautia group in the rumen. FTHFS sequences that probably originated from nonacetogens were identified by low "homoacetogen similarity" scores based on analysis of FTHFS residues, and comprised a large proportion of FTHFS sequences from the tammar wallaby forestomach. A diversity of FTHFS and ACS sequences in both ecosystems clustered between the Lachnospiraceae and Clostridiaceae acetogens but without close sequences from cultured isolates. These sequences probably originated from novel acetogens. The community structures of the acsB and fhs libraries from the rumen and the tammar wallaby forestomach were different (LIBSHUFF, P < 0.001), and these differences may have significance for overall hydrogenotrophy in both ecosystems

Marine biogeochemical responses to the North Atlantic Oscillation in a coupled climate model

In this study a coupled ocean-atmosphere model containing interactive marine biogeochemistry is used to analyze interannual, lagged, and decadal marine biogeochemical responses to the North Atlantic Oscillation (NAO), the dominant mode of North Atlantic atmospheric variability. The coupled model adequately reproduces present-day climatologies and NAO atmospheric variability. It is shown that marine biogeochemical responses to the NAO are governed by different mechanisms according to the time scale considered. On interannual time scales, local changes in vertical mixing, caused by modifications in air-sea heat, freshwater, and momentum fluxes, are most relevant in influencing phytoplankton growth through light and nutrient limitation mechanisms. At subpolar latitudes, deeper mixing occurring during positive NAO winters causes a slight decrease in late winter chlorophyll concentration due to light limitation and a 10%–20% increase in spring chlorophyll concentration due to higher nutrient availability. The lagged response of physical and biogeochemical properties to a high NAO winter shows some memory in the following 2 years. In particular, subsurface nutrient anomalies generated by local changes in mixing near the American coast are advected along the North Atlantic Current, where they are suggested to affect downstream chlorophyll concentration with 1 year lag. On decadal time scales, local and remote mechanisms act contemporaneously in shaping the decadal biogeochemical response to the NAO. The slow circulation adjustment, in response to NAO wind stress curl anomalies, causes a basin redistribution of heat, freshwater, and biogeochemical properties which, in turn, modifies the spatial structure of the subpolar chlorophyll bloom

Draft genome sequence of Treponema sp. strain JC4, a novel spirochete isolated from the bovine rumen

Morphologically and biochemically diverse members of the Treponema genus are present in the gastrointestinal tract of ruminants, yet very little is understood about their functional importance to this microbiome. Here we describe the annotated draft genome sequence of Treponema sp. strain JC4, a novel spirochete isolated from a bovine rumen sample

2018 REPORT ON OCCUPATIONAL FRAUD: RESULTS AND HOW COMPANIES CAN PROTECT THEIR ASSETS

The Association of Certified Fraud Examiners (ACFE) published their study on occupational fraud and abuse this past year. The study, which is its tenth edition, is the most comprehensive study on occupational fraud and abuse. Its findings give great insight into- among other things- who commits fraud, why they commit fraud, and how companies can protect themselves to deter and detect fraud. This paper will look at the major findings of the study. In addition, the paper will make practical suggestions that companies could implement to deter and detect fraud, with a special focus on internal controls and internal control activities

Senator Claude D. Pepper: Advocate of Aid to the Allies, 193901941

As a junior United States Senator from Florida during 1939-1941, Claude Denson Pepper was one of the most vocal advocates of conscription and aid to France and Britain. Having seen Adolph Hitler\u27s influence and popularity firsthand in 1938, he realized the threat that Nazi Germany presented to the European continent, Great Britain, and possibly the United States. Throughout 1939 and 1940, he spoke of the need for preparedness and became increasingly outspoken as the conflict in Europe intensified. With the help of presidential advisor Benjamin V. Cohen, he drafted two Senate bills for aid to the Allies in May 1940. Although they failed, both resolutions heightened debate and support for aid, later resulting in the Lend-Lease Act of early 1941. Pepper\u27s aggressiveness in promoting his beliefs brought public attention to interventionist ideas and conscription. When, in August 1940, the Congress of American Mothers, a coalition of right-wing women, hanged him in effigy, Pepper\u27s climb into the national spotlight was complete

The social security rights of older international migrants in the European Union

Europe is now home to a significant and diverse population of older international migrants. Social and demographic changes have forced the issue of social security in old age onto the European social policy agenda in the last decade. In spite of an increased interest in the financial well-being of older people, many retired international migrants who are legally resident in the European Union face structured disadvantages. Four linked factors are of particular importance in shaping the pension rights and levels of financial provision available to individual older migrants: migration history, socio-legal status, past relationship to the paid labour market, and location within a particular EU Member State. Building on a typology of older migrants, the paper outlines the ways in which policy at both the European Union and Member State levels serves to diminish rather than enhance the social security rights of certain older international migrants

Research on the application of a decoupling algorithm for structure analysis

The mathematical theory for decoupling mth-order matrix differential equations is presented. It is shown that the decoupling precedure can be developed from the algebraic theory of matrix polynomials. The role of eigenprojectors and latent projectors in the decoupling process is discussed and the mathematical relationships between eigenvalues, eigenvectors, latent roots, and latent vectors are developed. It is shown that the eigenvectors of the companion form of a matrix contains the latent vectors as a subset. The spectral decomposition of a matrix and the application to differential equations is given