Computer modeling of pulsed CO2 lasers for lidar applications

The experimental results will enable a comparison of the numerical code output with experimental data. This will ensure verification of the validity of the code. The measurements were made on a modified commercial CO2 laser. Results are listed as following. (1) The pulse shape and energy dependence on gas pressure were measured. (2) The intrapulse frequency chirp due to plasma and laser induced medium perturbation effects were determined. A simple numerical model showed quantitative agreement with these measurements. The pulse to pulse frequency stability was also determined. (3) The dependence was measured of the laser transverse mode stability on cavity length. A simple analysis of this dependence in terms of changes to the equivalent fresnel number and the cavity magnification was performed. (4) An analysis was made of the discharge pulse shape which enabled the low efficiency of the laser to be explained in terms of poor coupling of the electrical energy into the vibrational levels. And (5) the existing laser resonator code was changed to allow it to run on the Cray XMP under the new operating system

Leadership role of the Talented Tenth among Afro-Americans, 1895-1919

This thesis endeavours to examine W.E.B. DuBois' concept of a Talented Tenth as the black leadership elite of the period 1895-1919. It discusses the development, evolution and limitations of this idea, and attempts to compare the theory with the reality. It investigates the ideology of leadership within the black community, and suggests reasons for the motivation and goal selection of black leaders. Chapter 2 examines the social structure of the Talented Tenth, assessing its dimensions and socio-economic character¬ istics. Chapter 3 centres on the problems of inter-group communication, and describes both the agencies and the difficulties of this leadership function. It looks principally at the media of language, oratory, pub¬ lications and the press, and follows the adaptation of techniques to fit varying circumstances. The next chapter studies the intra-racial organisations which were dominated by the Talented Tenth, describing their aims and objects, com¬ position and structure, and resilience and durability. Chapter 5 surveys the debate within the Talented Tenth as to the most efficacious methods of attaining the desired ends, or solving the race problem. It contrasts agitation with gradualist tactics, and reviews the struggle with Booker T. Washington and the other factions aspiring to leadership, namely the politicians, the Church, the separatists, the demagogues, especially Marcus Garvey, and the socialists. Chapter 6 focuses on the special problems and the distinctive role of the black female intellectual, and her attempts to overcome the double handicap of racial and sexual prejudice. Chapter 7 analyses the participation of the Talented Tenth in interracial movements and the personal relationships that developed or failed to develop, with white sympathisers. It also examines the effect of white help, and the differing attitudes of the liberals and the philanthropists. The following two chapters discuss the reaction of the Talented Tenth to the issues of the "Negro Problem" in the American context, and then the attitudes of the Talented Tenth to the wider issues of American life or international situations. The final chapter attempts to collate the preceding evidence by assessing the role of the Talented Tenth as theorisers of the Afro- American experience. It claims that their role was of necessity practical rather than philosophical, and deals with their dilemma of portraying a favorable racial image to a dual audience. It looks at black writing in the white press and at black literature, viewing this period as the prelude to the Harlem Renaissance in the 1920's. In relating the development of racial ideologies, scientific and sociological arguments, and the growth of black history, it surveys the growth of race pricje and self-respect, the upsurge of social work and the concept of "social uplift". Finally, the chapter estimates the cohesion and co-operation of the group, and its outlook on its intraracial and inter-racial predicament

Effects of fescue toxicosis on growth and thermoregulation of rats [abstract]

Abstract only availableFaculty Mentor: Don Spiers, Animal SciencesTall fescue (Festuca arundinacia), a cool season forage grass, has been utilized by many farmers for over fifty year to feed livestock. Unfortunately, about half of fescue pastures are infected with an endophytic fungus (Acremonium coenophialum). The fungus produces toxins which cause health and reproduction problems in animals resulting in economic losses. Previous studies have found that intake of infected fescue during hot weather produces hyperthermia, rough hair coats, increased respiration rates, lowered milk production, dystosia, lameness, decreased feed intake and average daily gain, and reduced prolactin, progesterone, and cholesterol levels. This study was done to investigate the effects of heat stress combined with infected tall fescue seed and associated decreased feed intake on male reproduction. Twelve male rats were implanted with telemetric thermometers (Mini-Mitter, Inc.) to record core body temperature and activity every ten minutes. Rats were randomly assigned to either heat stress (HS; 31o C) or thermoneutral conditions (TN; 21o C) and fed one of three diets: endophyte-infected seed (E+), endophyte-free seed (E-), or E- diet fed in the same amount as consumed by the E+ rats the preceding day. Feed intake and body weight were recorded daily. Semen was examined for sperm motility, concentration and morphology. Tissue samples were removed from testis, epidymis, seminal vesicles, and liver and examined histologically. Other organs were collected and weighed. Toxin, heat stress, or feed restriction caused a similar reduction in growth rate, but all showed some recovery by the end of the study (

Fescue toxicosis affects the reproduction and thermoregulatory systems of male rats exposed to heat stress

Abstract only availableTall fescue (Festuca arundinacia), a cool season forage grass, has been utilized by many farmers for over fifty year to feed livestock. Unfortunately, about half of fescue pastures are infected with an endophytic fungus (Acremonium coenophialum). The fungus produces toxins which cause health and reproduction problems in animals resulting in economic losses. Previous studies have found that intake of infected fescue during hot weather produces hyperthermia, rough hair coats, increased respiration rates, lowered milk production, dystosia, lameness, decreased feed intake and average daily gain, and reduced prolactin, progesterone, and cholesterol levels. This study was done to investigate the effects of heat stress combined with infected tall fescue seed and associated decreased feed intake on male reproduction. Twelve male rats were implanted with telemetric thermometers (Mini-Mitter, Inc.) to record core body temperature and activity every ten minutes. Rats were randomly assigned to either heat stress (HS; 31 C) or thermoneutral conditions (TN; 21 C) and fed one of three diets: endophyte-infected seed (E+), endophyte-free seed (E-), or E- diet fed in the same amount as consumed by the E+ rats the preceding day. Feed intake and body weight were recorded daily. Semen was examined for sperm motility, concentration and morphology. Tissue samples were removed from testis, epidymis, seminal vesicles, and liver and examined histologically. Other organs were collected and weighed. Toxin, heat stress, or feed restriction caused a similar reduction in growth rate, but all showed some recovery by the end of the study (P< .0013). Liver (P< .0096) and heart (P< .01) weights decreased in treatment animals. Core body temperature showed differences between treatments; E+ rats showed hyperthermia and adaptation towards the end of the study. Activity was extremely variable and no conclusions could be drawn, given that each group was assigned only 1-2 animals. There was no significant effect on kidney, adrenal, spleen, testes, and seminal vesicle weight. The rough hair coat characteristic of fescue toxicosis was also observed in E+ rats. Analysis of sperm function and morphology are being conducted. Understanding the interaction between fescue toxins, heat stress, nutrition, and reproduction function will help in finding a treatment for fescue toxicosis and developing management strategies.Life Sciences Undergraduate Research Opportunity Progra

Toward Universal Broadband in Rural Alaska

The TERRA-Southwest project is extending broadband service to 65 communities in the Bristol Bay, Bethel and Yukon-Kuskokwim regions. A stimulus project funded by a combination of grants and loans from the Rural Utilities Service (RUS), TERRA-Southwest has installed a middle-mile network using optical fiber and terrestrial microwave. Last-mile service will be through fixed wireless or interconnection with local telephone networks. The State of Alaska, through its designee Connect Alaska, also received federal stimulus funding from the National Telecommunications and Information Administration (NTIA) for tasks that include support for an Alaska Broadband Task Force “to both formalize a strategic broadband plan for the state of Alaska and coordinate broadband activities across relevant agencies and organizations.” Thus, a study of the impact of the TERRA project in southwest Alaska is both relevant and timely. This first phase provides baseline data on current access to and use of ICTs and Internet connectivity in rural Alaska, and some insights about perceived benefits and potential barriers to adoption of broadband. It is also intended to provide guidance to the State Broadband Task Force in determining how the extension of broadband throughout the state could contribute to education, social services, and economic activities that would enhance Alaska’s future. Results of the research could also be used proactively to develop strategies to encourage broadband adoption, and to identify applications and support needed by users with limited ICT skills.Connect Alaska. The National Telecommunications and Information Administration. General Communications Incorporated.Part 1: An Analysis of Internet Use in Southwest Alaska / Introduction / Previous Studies / Current Connectivity / Analytical Framework and Research Methodology / Demographics / Mobile Phones: Access and Use / Access to the Internet / Internet Useage / Considerations about Internet Service / Interest in Broadband / Sources of News / Comparison with National Data / Internet Use by Businesses and Organizations / What Difference may Broadband make in the Region? / Conclusiongs / Part 2 Literature Review / Reference

A feed-restriction model to identify factors responsible for fescue toxicosis-induced reduction in food intake [abstract]

Abstract only availableFescue toxicosis results from intake of ergopeptine alkaloids derived from a fungus (Neotyphodium coenophialum ) in tall fescue, and produces reduced productivity. Contributors to this reduction are decreased feed intake and growth. There have been few attempts to characterize these changes. A study was conducted to develop a model for this component using rats in a feed restriction experiment described previously by others. Each animal was trained over a minimum 11 d period to eat their entire daily ration from 1300-1500. This allows one to evaluate the effect of potential treatments more precisely by using a 2 hours rather than 24. Group I animals were first fed in this order an endophyte-free seed (E-) diet (ad libitum ), a restricted E- diet, a restricted endophyte-infected seed (E+) diet, and lastly an E- diet (ad libitum ). There was no decrease in feed intake (α= 0.05) from restricted E- to restricted E+ diets, but reduced growth while on E+ diet. Return to E- diet restored growth. A different routine was used with Group II. Rats were first fed ground commercial diet (ad libitum ), followed by restricted ground diet, restricted E- diet, and lastly restricted E+ diet. Initial exposure to restricted diet decreased feed intake and growth (α = 0.05), followed by partial recovery or adaptation over following 4 days. Shift to restricted E- produced no change in feed intake and a greater return of growth. Restricted E+ diet intake reduced feed intake and growth within 24 hours (α = 0.05). This reduction was stable over the entire 2 week period. These responses agree with previous studies using long-term ad libitum E+ treatment. This new model can now be used to identify mechanisms for fescue toxicosis-induced reduction in feed intake and growth, and develop potential treatments

Place Field Repetition and Purely Local Remapping in a Multicompartment Environment

Hippocampal place cells support spatial memory using sensory information from the environment and self-motion information to localize their firing fields. Currently, there is disagreement about whether CA1 place cells can use pure self-motion information to disambiguate different compartments in environments containing multiple visually identical compartments. Some studies report that place cells can disambiguate different compartments, while others report that they do not. Furthermore, while numerous studies have examined remapping, there has been little examination of remapping in different subregions of a single environment. Is remapping purely local or do place fields in neighboring, unaffected, regions detect the change? We recorded place cells as rats foraged across a 4-compartment environment and report 3 new findings. First, we find that, unlike studies in which rats foraged in 2 compartments, place fields showed a high degree of spatial repetition with a slight degree of rate-based discrimination. Second, this repetition does not diminish with extended experience. Third, remapping was found to be purely local for both geometric change and contextual change. Our results reveal the limited capacity of the path integrator to drive pattern separation in hippocampal representations, and suggest that doorways may play a privileged role in segmenting the neural representation of space

Inter-individual variation in nucleotide excision repair in young adults: effects of age, adiposity, micronutrient supplementation and genotype

Nucleotide excision repair (NER) is responsible for repairing bulky helix-distorting DNA lesions and is essential for the maintenance of genomic integrity. Severe hereditary impairment of NER leads to cancers such as those in xeroderma pigmentosum, and more moderate reductions in NER capacity have been associated with an increased cancer risk. Diet is a proven modifier of cancer risk but few studies have investigated the potential relationships between diet and NER. In the present study, the plasmid-based host cell reactivation assay was used to measure the NER capacity in peripheral blood mononuclear cells from fifty-seven volunteers aged 18–30 years before and after 6 weeks of supplementation with micronutrients (selenium and vitamins A, C and E). As a control, nine individuals remained unsupplemented over the same period. Volunteers were genotyped for the following polymorphisms in NER genes: ERCC5 Asp1104His (rs17655); XPC Lys939Gln (rs2228001); ERCC2 Lys751Gnl (rs13181); XPC PAT (an 83 bp poly A/T insertion–deletion polymorphism in the XPC gene). NER capacity varied 11-fold between individuals and was inversely associated with age and endogenous DNA strand breaks. For the first time, we observed an inverse association between adiposity and NER. No single polymorphism was associated with the NER capacity, although significant gene–gene interactions were observed between XPC Lys939Gln and ERCC5 Asp1104His and XPC Lys939Gln and ERCC2 Lys751Gnl. While there was no detectable effect of micronutrient supplementation on NER capacity, there was evidence that the effect of fruit intake on the NER capacity may be modulated by the ERCC2 Lys751Gnl single nucleotide polymorphism

The experience of antiretroviral treatment for Black West African women who are HIV positive and living in London: an interpretative phenomenological analysis

Antiretroviral therapy (ART) offers a powerful intervention in HIV but effectiveness can be compromised by inadequate adherence. This paper is a detailed examination of the experience of medication in a purposively selected group of people living with HIV. In-depth interviews were conducted with 10 HIV positive, West African women of black heritage living in London, UK. This group was of interest since it is the second largest group affected by HIV in the UK. Interviews were subjected to interpretative phenomenological analysis, an idiographic, experiential, qualitative approach. The paper details the women’s negative experience of treatment. ART can be considered difficult and unrelenting and may be disconnected from the women’s sense of health or illness. Participants’ social context often exacerbated the difficulties. Some reported an improvement in their feelings about the medication over time. These findings point to some intrinsic and social motivators which could act as spurs to adherence