James Alexander was born on August 21, 1832. Raised in Augusta County, Virginia, he was an active youth. In 1848, he entered the Virginia Military Institute. Though a fine student, in 1852, he was dismissed for his poor conduct in the class of Major Thomas J. Jackson. In the years before the Civil War, Walker worked as an engineer, teacher and lawyer. Settling in New Bern in southwest Virginia’s Pulaski County, Walker became a captain of the “Pulaski Guard.” During the war, Walker rose from captain of Company C of the 4th Virginia, to lieutenant colonel of the 4th, to colonel of the 13th Virginia and finally to brigadier general and last commander of the famed Stonewall Brigade. After the war, Walker made his fortune through his legal practice and land investments in Pulaski and Wythe counties. He was a success in politics, he was twice a member of Virginia’s House of Delegates, a lieutenant governor of Virginia and a member of the Fifty-Fourth and Fifty-Fifth Congresses. On October 22, 1901, he died as a man who made his mark on Virginia history. / Master of Arts

Proponents of labeling theory argue that the labels we use to identify things are not merely harmless words, but, in fact, shape and control experience to some degree. Others, such as W. E. B. Dubois, argued that names only identify things and if one changes a label by which a thing is identified the meaning will not be changed. The major aim of the present study was to determine if there were any significant differences in responses elicited from a random sample of the white population of Roanoke, Virginia, by using varied minority group labels (Negro, Colored, Afro-American, Black). The random sample of 800 was divided into four groups cf 200, each receiving a different form of the questionnaire. Proposed differentiation responses were measured by the use of mean prejudice scores on a cognitive, emotional and action level. The data revealed that there was no significant differences in prejudice scores elicited by the use of varied minority group labels (Negro, Colored, Afro-American, Black). This study, as opposed to traditional labeling-theory, utilizes the group as the unit of analysis and did not presume the passivity of the labelee. Therefore this would tend to indicate that labeling theory, when the unit of analysis is the group, should take into consideration resistance to and counter-application of labels by the labelees. / Master of Science

No description available.

PURPOSE: The purpose of this study was twofold: 1. To select and develop two laboratory approaches for teaching basic woodworking technology to students in agricultural mechanics. 2. To compare student performances of the two laboratory approaches both on the college level and on the high school level. PROCEDURES: The development phase of this study involved the selection and preparation of desired student behavioral outcomes, curriculum, content and materials, two laboratory teaching methods, and student performance measuring instruments for basic woodworking technology. One trial comparison experiment was conducted on the college level with two matched groups of juniors enrolled in agricultural mechanics at Virginia Polytechnic Institute. Each group consisted of eight students. One experiment was conducted on the high school level with two matched groups, each consisting of six high school sophomores. The project-oriented laboratory teaching method was selected for use by the control groups of each experiment. The method used by the experimental groups in both experiments was the "timed-learning experience laboratory method." This method was developed by the writer. CONCLUSIONS: The following conclusions were formulated from the data collected in the experiments: 1. In the college experiment the students taught by the "timed-learning experience laboratory method" had a greater average percentage of gain on both the written and the laboratory test than the students taught by the project-oriented method. 2. In the high school experiment the students taught by the "timed-learning experience laboratory method” had a greater average percentage of gain on both the writtten and the laboratory test than the students taught by the project oriented method. / M.S.

This study is concerned with the simultaneous detection and least squares estimation of vector random processes. The problem is formulated in the following context: A random process, out of a countably infinite collection of (not necessarily Gaussian) vector random processes with known distributions, is observed with additive white Gaussian noise. The <i>a priori</i> probability, that a specific random process will be observed, is specified for each one in the collection. The least squares estimate of the random process that is being observed is to be found in terms of the hypothesis conditioned estimates. It is shown that the best estimate is the linear combination of the hypothesis conditioned estimates weighted by the <i>a posteriori</i> probabilities of the hypotheses conditioned on the observations. A Radon-Nikodym derivative representation is derived for the <i>a posteriori</i> probability by using the specific structure of the product probability measure for this problem. It is shown that this Radon-Nikodym derivative can be expressed in terms of the Radon-Nikodym derivatives of measures induced by the random processes in the collection with respect to Wiener measure. By using the recent results on likelihood functions, an expression for the <i>a posteriori</i> probability is found in terms of the conditioned estimates. In this connection, an extended version of the partition theorem of parameter adaptive estimation is proved. The unique stochastic differential equation, that each <i>a posteriori</i> probability satisfies with its associated <i>a posteriori</i> probability as the initial condition, is derived for the case of finitely many hypotheses along with an expression for the conditional error covariance in terms of the hypothesis conditioned error covariances. The results are applied to the parameter adaptive estimation problem in linear continuous and discrete stochastic dynamic systems. In the continuous case, the solution is also obtained through an alternate approach using nonlinear filtering theory. An application of the theory to the design of a digital flight control system which is tolerant of sensor failures is presented with real-time hybrid computer simulation results. A review of random processes and statistical decision theory is also included. / Ph. D.

This paper investigates the role of credit market sentiments and investor beliefs on credit cycle dynamics and their propagation to business cycle fluctuations. Using US data from 1968 to 2019, we show that credit market sentiments are indeed able to detect asymmetries in a small-scale macroeconomic model. By exploiting recent developments in behavioral finance on expectation formation in financial markets, we are able to identify an unexpected credit market news shock exhibiting different impacts in an optimistic and pessimistic credit market environment. While an unexpected movement in the optimistic regime leads to a rather low to muted impact on output and credit, we find a significant and persistent negative impact on those variables in the pessimistic regime. Therefore, this article departs from the current literature on the role of financial frictions for explaining business cycle behavior in macroeconomics and argues in line with recent theoretical contributions on the relevance of expectation formation and beliefs as source of cyclicity and instability in financial markets. / Series: Department of Economics Working Paper Series

La première étape du cycle viral du virus de l'immunodéficience humaine se déroule grâce à l'interaction entre les glycoprotéines d'enveloppe gp120/gp41 et les récepteurs CD4 et CCR5/CXCR4. Les différentes fonctions activées par cette étape, incluant l'attachement, la pénétration et la signalisation cellulaire représentent des cibles potentielles pour le développement d'antirétroviraux. Dans ce travail, nous avons développé des approches permettant d'agir sur chacune de ces étapes à l'aide de peptides synthétiques, d'anticorps anti-peptide et d'inhibiteurs des voies de signalisation. Dans la première approche, nous nous sommes intéressé au développement d'analogues peptidiques de la région HRII en évitant les limitations, incluant courte demi-vie et émergence d'isolats de résistance, rencontrées lors de l'utilisation du peptide T-20 (Fuzeon). Nous avons synthétisé un peptide de 34 acides aminés modélisant la région HRII en incluant des acides aminés non naturels de série D uniquement au niveau de certains sites sensibles à la protéolyse ou dans la totalité de la séquence.Les résultats obtenus montrent que les modifications ponctuelles permettent de : i) maintenir la structure en hélice a du peptide, ii) maintenir sa capacité à interagir avec la région HRI, iii) d'augmenter sa demie-vie et iv) de conserver son activité antivirale. Dans la deuxième approche, nous avons testé la capacité des peptides analogues de la région HRII de VIH-1 et de la boucle V3 de SIV à induire la production d'anticorps neutralisants. Cette étude nous a permis d'aboutir à deux conclusions principales : i) les anticorps anti-HRII peuvent interférer avec l'activité antivirale du peptide administré lors du traitement antiviral, ii) contrairement aux anticorps anti-V3 du VIH-1, les anticorps anti-V3 de SIV sont incapables de neutraliser le virus SIV suggérant des fonctions différentes pour cette région chez HIV-1 et SIV. Dans la troisième partie, nous avons montré que l'attachement du virus VIH sur son récepteur s'accompagne de l'activation de la voie PKC dont l'isoforme PKC-d. L'inhibition de cet isoforme bloque totalement la réplication virale. Ce blocage semble s'opérer en interférant avec les étapes post-entrée du virus en inhibant la formation des pseudopodes et des filaments d'actine, structure nécessaire pour l'étape de la transcription inverse.

Doctor en Ciencias de la Ingeniería, Mención Ingeniería Química y Biotecnología / Streptomyces leeuwenhoekii C34 es un actinomiceto aislado del desierto de Atacama, Chile, productor de los antibióticos chaxamicinas A a D y chaxalactinas A a C. El objetivo de este trabajo fue identificar los genes involucrados en la biosíntesis de chaxamicinas y chaxalactinas y producir chaxamicinas en un huésped heterólogo. Capítulo Uno detalla procedimientos de crecimiento y modificación genética de S. leeu- wenhoekii C34. La temperatura óptima para producción de chaxamicinas en medio líquido fue 30 °C, y la que permitió alcanzar altos niveles de esporulación en medio sólido fue 37 °C. S. leeuwenhoekii C34 fue sensible a tioestreptona, apramicina, higromicina B y kanamicina, mientras que no a ácido nalidíxico, antibióticos usados para seleccionar bac- terias genéticamente modificadas. Un vector sensible a temperatura (pGM1190) y otro con un sistema de integración del fago C31 (pSET152) fueron exitosamente transferi- dos a S. leeuwenhoekii C34 por conjugación con una cepa que no metila ADN, E. coli ET12567/pUZ8002. Suplementación del medio de conjugación con 120 mM MgCl2 ó 60 mM CaCl2, incrementó la frecuencia de conjugación de forma significativa, comparado con el control sin adición de sales. En este trabajo se demostró que S. leeuwenhoekii C34 incorpora ADN foráneo no metilado. Capítulo Dos describe la identificación y expresión heteróloga de los genes de biosín- tesis de chaxamicinas. El genoma de S. leeuwenhoekii C34 fue secuenciado de novo combinando tecnologías de secuenciación Illumina y PacBio. Un grupo de 27 genes (80,2 kb, locus 1.210.347 1.290.550), codifica enzimas para la biosíntesis de chaxam- icinas. pIJ12853 contenía un inserto del genoma de S. leeuwenhoekii C34 de 145 kb que incluye el segmento de 80,2 kb, el que fue transferido a una cepa que no produce chaxamicinas, S. coelicolor M1152, resultando en la producción de chaxamicinas A D, confirmando que los genes presentes en pIJ12853 codifican para la ruta de biosíntesis de chaxamicinas. Genes del huésped heterólogo podrían estar involucrados en biosíntesis y/o exporte de estas moléculas. La deleción del gen AHBA sintasa (cxmK) en S. leeu- wenhoekii C34, dio origen a la cepa M1653 que pierde su capacidad de producir chax- amicinas. Para demostrar que la interrupción en la producción de chaxamicinas fue sólo debido a su incapacidad de producir AHBA, un cultivo líquido de M1653 suplementado con AHBA comercial permitió restablecer la producción de chaxamicinas. Esto es una prueba más de que el los genes de biosíntesis de chaxamicinas fueron identificados. Capítulo Tres describe la identificación bioinformática de los genes de biosíntesis de chaxalactinas. Una secuencia de 80,7 kb (locus 7.146.903 7.227.608) contenía genes codificantes de 5 subunidades de una policétido sintasa, cuya arquitectura de dominios coincidía con la predicha para biosíntesis de chaxalactina A. Un gen que codifica una citocromo P450 sería responsable de la hidroxilación C-14 de chaxalactina A que da ori- gen a chaxalactina B. Dos genes codificantes de O-metiltransferasas estarían involucra- dos en una O-metilación C-13 de chaxalactina B, que da origen a chaxalactina C.

Methods of calculating the inbreeding coefficient In a finite population undergoing recurrent selection (self-select-intercross in succeeding generations) were investigated. It was noted that, in a population under selection, the inbreeding coefficient does not provide the experimenter with a measure of expected degree of variability; instead an index of total heterozygosity is required, and such an Index was derived. Formulas necessary to calculate both the inbreeding coefficients and the heterozygosity indexes were derived for the cases: one-locus, two-allele, random selection; k independent loci and random selection; one-locus, two-allele and effective directional selection; and k linked loci with effective directional selection. These formulas Involved defining a generalized inbreeding coefficient and a generalized index of homozygosity (or heterozygosity) in terms of vectors whose components reflected the various possible patterns of genes identical by descent at a given stage of the recurrent selection breeding program. Formulas were derived whereby the mean and the variance of the total number of loci homozygous (or heterozygous) by descent or in state may be obtained. The progress of the panmictic index and/or the index of total heterozygosity through at least twenty-five cycles of recurrent selection was observed in computer-simulated populations ranging in sizes from ten through one hundred, assuming varying recombination probabilities both in the one-locus and in the two linked-loci case and assuming both minimum and maximum inbreeding selection patterns. Tables resulting from these simulated studies could be used to estimate minimum and maximum inbreeding coefficients and/or minimum and maximum heterozygosity indexes in experimental populations for which the initial conditions approximate those assumed in the simulated populations. It was observed that the coefficient of relationship in the source population was extremely important in tracing the progress of the degree of Inbreeding and/or total homozygosity, that linkage played a major role in promoting heterozygosity in a recurrent selection system, and that careful intercrossing rather than random mating in alternate generations of the recurrent selection cycle was important in promoting maximum heterozygosity in the selected population. In the simulated populations the effect of small population sizes was observed and, in general, indications were that unless more than five complete recurrent cycles are contemplated, increasing population size results In only relatively minor increases in panmixia, especially when linked loci are involved in the selected trait and when care Is taken to avoid a maximum inbreeding selection pattern. / Ph. D.