Selenium toxicity: cause and effects in aquatic birds

There are several manners in which selenium may express its toxicity: (1) an important mechanism appears to involve the formation of CH3Se− which either enters a redox cycle and generates superoxide and oxidative stress, or forms free radicals that bind to and inhibit important enzymes and proteins. (2) Excess selenium as selenocysteine results in inhibition of selenium methylation metabolism. As a consequence, concentrations of hydrogen selenide, an intermediate metabolite, accumulate in animals and are hepatotoxic, possibly causing other selenium-related adverse effects. (3) It is also possible that the presence of excess selenium analogs of sulfur-containing enzymes and structural proteins play a role in avian teratogenesis. ʟ-selenomethionine is the most likely major dietary form of selenium encountered by aquatic birds, with lesser amounts of ʟ-selenocysteine ingested from aquatic animal foods. The literature is suggestive that ʟ-selenomethionine is not any more toxic to adult birds than other animals. ʟ-Selenomethionine accumulates in tissue protein of adult birds and in the protein of egg white as would be expected to occur in animals. There is no suggestion from the literature that the levels of ʟ-selenomethionine that would be expected to accumulate in eggs in the absence of environmental concentration of selenium pose harm to the developing embryo. For several species of aquatic birds, levels of Se as selenomethionine in the egg above 3 ppm on a wet weight basis result in reduced hatchability and deformed embryos. The toxicity of ʟ-selenomethionine injected directly into eggs is greater than that found from the entry of ʟ selenomethionine into the egg from the normal adult diet. This suggests that there is unusual if not abnormal metabolism of ʟ-selenomethionine in the embryo not seen when ʟ-selenomethionine is present in egg white protein where it likely serves as a source of selenium for glutathione peroxidase synthesis in the developing aquatic chick

Limnological, Ichthyological, and Parasitological Investigations on Arkansas Reservoris in Relation to Water Quality

Lake Fort Smith, a 525 acre (212 ha) reservoir, was impounded in 1936 as a water supply for the city of Fort Smith. The reservoir is located on Clear Creek (Frog Bayou), a tributary of the Arkansas River, in the Boston Mountains 28 miles (45 km) northeast of the city of Fort Smith in Crawford County, Arkansas. A map and morphometric characteristics of Lake Fort Smith are given in Fig. 1 and Table I (Hoffman, 1951; Nelson, 1952). In 1956 Lake Shepherd Springs, a 750 acre (304 ha) impoundment, was created one mile upstream of Lake Fort Smith (Rorie, 1961). Both lakes have a shale substrate and are subject to periods of high turbidity. The 2 two lakes have a water shed of 65 square mile area (168 km ) of mountainous oak-hickory forest. Lake Shepherd Springs has not acted as a settling basin for sediments; thus, the upper portion of Lake Fort Smith has numerous shallow areas with a mud bottom supporting various submergent and emergent aquatic plants. The lower portion of the lake has a rocky, shale substrate with only limited emergent vegetation

Space Station Freedom automation and robotics: An assessment of the potential for increased productivity

This report presents the results of a study performed in support of the Space Station Freedom Advanced Development Program, under the sponsorship of the Space Station Engineering (Code MT), Office of Space Flight. The study consisted of the collection, compilation, and analysis of lessons learned, crew time requirements, and other factors influencing the application of advanced automation and robotics, with emphasis on potential improvements in productivity. The lessons learned data collected were based primarily on Skylab, Spacelab, and other Space Shuttle experiences, consisting principally of interviews with current and former crew members and other NASA personnel with relevant experience. The objectives of this report are to present a summary of this data and its analysis, and to present conclusions regarding promising areas for the application of advanced automation and robotics technology to the Space Station Freedom and the potential benefits in terms of increased productivity. In this study, primary emphasis was placed on advanced automation technology because of its fairly extensive utilization within private industry including the aerospace sector. In contrast, other than the Remote Manipulator System (RMS), there has been relatively limited experience with advanced robotics technology applicable to the Space Station. This report should be used as a guide and is not intended to be used as a substitute for official Astronaut Office crew positions on specific issues

Meanders: Exact Asymptotics

We conjecture that meanders are governed by the gravitational version of a c=-4 two-dimensional conformal field theory, allowing for exact predictions for the meander configuration exponent \alpha=\sqrt{29}(\sqrt{29}+\sqrt{5})/12, and the semi-meander exponent {\bar\alpha}=1+\sqrt{11}(\sqrt{29}+\sqrt{5})/24. This result follows from an interpretation of meanders as pairs of fully packed loops on a random surface, described by two c=-2 free fields. The above values agree with recent numerical estimates. We generalize these results to a score of meandric numbers with various geometries and arbitrary loop fugacities.Comment: new version with note added in proo

inbreedR: An R package for the analysis of inbreeding based on genetic markers

1. Heterozygosity fitness correlations (HFCs) have been used extensively to explore the impact of inbreeding on individual fitness. Initially, most studies used small panels of microsatellites, but more recently with the advent of next generation sequencing, large SNP datasets are becoming increasingly available and these provide greater power and precision to quantify the impact of inbreeding on fitness. 2. Despite the popularity of HFC studies, effect sizes tend to be rather small. One reason for this may be a low variation in inbreeding level across individuals. Using genetic markers, it is possible to measure variance in inbreeding through the strength of correlation in heterozygosity across marker loci, termed identity disequilibrium (ID). 3. ID can be quantified using the measure g2 which is also a central parameter in HFC theory that can be used within a wider framework to estimate the direct impact of inbreeding on both marker heterozygosity and fitness. However, no software exists to calculate g2 for large SNP datasets nor to implement this framework. 4. inbreedR is an R package that provides functions to calculate g2 based on microsatellite and SNP markers with associated p-values and confidence intervals. Within the framework of HFC theory, inbreedR also estimates the impact of inbreeding on marker heterozygosity and fitness. Moreover, we implemented easy-to-use simulations to explore the precision and magnitude of estimates based on different numbers of genetic markers. We hope this package will facilitate good practice in the analysis of HFCs and help to deepen our understanding of inbreeding effects in natural populations

The first amendment rights of high school newspapers in Virginia

As the result of Tinker v. Pes Moines (1969) students have become more aware of their constitutional rights. However, the First Amendment rights of student newspapers have been abridged even after the Tinker decision stated that students' rights did not end at the schoolhouse gate. Even though the courts have recognized certain rights of both the student press and the professional press, areas of litigation during the past few years have involved obscenity, libel, and prior restraint. Of these three abridgments, the imposition of prior restraint by school administrators tends to be the greatest threat to a free student press. This study was begun with the intention of defining student press rights by reviewing major court cases involving the professional press as well as the student press, studying the literature in the area of the student press, and sending a questionnaire to the high school newspaper advisers in Virginia

Information preserving structures: A general framework for quantum zero-error information

Quantum systems carry information. Quantum theory supports at least two distinct kinds of information (classical and quantum), and a variety of different ways to encode and preserve information in physical systems. A system's ability to carry information is constrained and defined by the noise in its dynamics. This paper introduces an operational framework, using information-preserving structures to classify all the kinds of information that can be perfectly (i.e., with zero error) preserved by quantum dynamics. We prove that every perfectly preserved code has the same structure as a matrix algebra, and that preserved information can always be corrected. We also classify distinct operational criteria for preservation (e.g., "noiseless", "unitarily correctible", etc.) and introduce two new and natural criteria for measurement-stabilized and unconditionally preserved codes. Finally, for several of these operational critera, we present efficient (polynomial in the state-space dimension) algorithms to find all of a channel's information-preserving structures.Comment: 29 pages, 19 examples. Contains complete proofs for all the theorems in arXiv:0705.428

West Nile Virus Viremia in Wild Rock Pigeons

Feral rock pigeons were screened for neutralizing antibodies to West Nile virus (WNV) during late winter/spring and summer of 2002 and 2003. Additionally, virus isolation from serum was attempted from 269 birds collected during peak transmission periods. The observed viremia levels and seroprevalence indicate that this species could be involved in amplifying WNV in urban settings

Autonomous Tennis Ball Collector

Practicing tennis often involves hitting many tennis balls from one side of the court to the other without an opponent to hit the balls back. In training sessions like these, the task of collecting the balls is laborious when performed manually. The objective of this project is to develop a robotic tennis ball collector that can automatically collect the balls from one side of the court so that the player can rest rather than collect the balls manually. This document outlines the process of designing such a robot. Included in this report is background research, prototype, and concept modeling, along with a finalized design, and a complete timeline of our process. We will also detail the manufacturing process and the design verification. In the conclusion we will provide you with recommendations for future projects. Throughout our research, we discovered many similar products, but none met all of the customer’s requirements, thus opening a window for our product. After copious design consideration, we selected the strongest idea that satisfied our customers’ needs and are moving forward with structural modeling and preliminary analysis on it. After the structural prototype revealed issues in the design we went back to work and finalized a design that we felt confident with and still satisfied all the requirements. As seen in this report the final design utilizes structural framing materials to build the robot and allows for ease of attachment for all the electrical components. The final step in the design process was to test the verification prototype to ensure that it met all our specifications. Unfortunately, our design did not pass as many of the tests as we would have liked, and this is detailed in that section. While at the conclusion of this project, we did not complete as much as we hoped, there is a good foundation in place for the project to continue as our sponsor so desires