« La littérature en systèmes d'information énonce plusieurs recommandations sur la façon de concevoir, administrer et implanter un système d'information. Cette recherche s'intéresse aux suggestions qui concernent la conception et l'implantation d'un système d'information en vérifiant leur présence dans la pratique québécoise de même que leur relation au succès d'un système d'information. Les recommandations vérifiées sont la résultante d'une revue de la littérature qui permit de retenir une liste de suggestions que nous identifions comme "facteurs de succès". Ces suggestions furent soumises à l'évaluation d'experts en systèmes d'information. Ces évaluations furent par la suite analysées, ce qui réduisit le nombre de facteurs de succès pertinents à 16. La satisfaction informationnelle de l'usager d'un système d'information est le critère utilisé dans cette recherche pour mesurer le succès d'un système. Ce concept de satisfaction informationnelle fut validé par une étude empirique auprès d'usagers de systèmes d'information. Utilisé comme instrument de mesure, une analyse permit de le définir comme suit: c'est la résultante de l'agrégation des évaluations que fait l'usager des attributs suivants de l'information que lui fournit un système d'information: accessible, à jour, adaptée, compréhensible, flexible, pertinente, simple, utile, complète, fiable, à temps et concise. Les données qui ont servi à atteindre les objectifs de cette recherche furent cueillies par questionnaires auprès de 375 usagers et de 107 concepteurs de systèmes dans 19 organisations des secteurs public, para-public et privé. Ces données permettent de conclure à la présence des facteurs de succès dans la pratique québécoise. La théorie et la pratique sont donc rapprochées puisque la très grande majorité des facteurs de succès sont utilisés par les praticiens du Québec. Deuxième objectif de cette recherche, une analyse des résultats obtenus permet de conclure que les facteurs de succès sont reliés significativement à la satisfaction informationnelle de l'usager. C'est ainsi que, dans le secteur public 6 des 16 facteurs sont corrélés significativement à la satisfaction informationnelle, 3 dans le secteur para-public et 1 dans le secteur privé. Pour l'ensemble des 3 secteurs à la fois, 11 facteurs sur 16 sont reliés significativement à la satisfaction informationnelle. Les contributions les plus importantes de cette recherche se situent au niveau de la validation empirique de certains principes mentionnés dans la littérature, au niveau du développement du concept de satisfaction informationnelle, ainsi que du développement et de la validation d'un instrument permettant de la mesurer. Finalement, pour les concepteurs et analystes qui acceptent la satisfaction informationnelle comme critère de succès, cette recherche contient plusieurs éléments qui peuvent servir de guide au développement d'un système d'information. »--Pages xi-xii

There have been the formation of mother-infant support groups due to an awareness that women need support in their role as mother. The fifty-three women studied attended An Ongoing Seminar Series: Mothers and Infants in Alexandria, Virginia. The study was an exploratory, descriptive collection of data on the participants' backgrounds, characteristics of their post-partum experience, and their personal evaluation of the seminar. There were sixty-two percent of the questionnaires returned. A variable analysis of the one hundred thirty- ' four variables was undertaken. On four sections of the questionnaire items were rated on a scale. Group scores were analyzed for each of these sections. Participants in this study were seen as socially motivated and intelligent women experiencing post-partum adjustment in balancing their time commitment in the roles of wife, mother, and person. This was coupled with a unanimous feeling of chronic tiredness. The seminar provided social contact with others that shared these same feelings. It did not always provide mothers with certain expertise and solution oriented discussions that they desired. A re-evaluation of the seminar format and content could better meet the mothers' needs. / M.S.

The linearized Vlasov-Maxwell equations describing anisotropic plasma oscillations and waves are studied using an operator theoretic approach. The model considered is one dimensional so that after velocity averages perpendicular to this direction. have been taken, the equations can be naturally grouped into one set of equations for longitudinal modes and another set of equations for transverse modes. The problems of longitudinal and transverse plasma oscillations are studied by Fourier transforming the equations in the space variable and analyzing the resulting operator equations using the theory of semigroups. Existence and uniqueness theorems are proved, and solutions are constructed by the resolvent integration technique. The solutions are put into the form of a generalized eigenfunction expansion with eigenmodes corresponding to zeros of the appropriate plasma dispersion function. The expansion coefficients for eigenmodes corresponding to simple and second order real zeros of the plasma dispersion function are also presented, and constitute some of the new results obtained by our analysis. Existence and uniqueness of the solution to the longitudinal plasma wave boundary value problem is proved by writing the longitudinal equations in operator form and again using the theory of semigroups. The solution to the plasma wave boundary value problem is arrived at by a Fourier time transformation of the Vlasov equation coupled to Ampere's Law rather than Gauss‘ Law, and analyzing a scalar operator as opposed to the more complicated matrix operator that has previously been studied. Special care is used in constructing the half range transport operator whose resolution of the identity yields the solution in the form of a half range generalized eigenfunction expansion where again, new results are presented for the expansion coefficients for eigenfunctions corresponding to simple and second order real zeros of the fixed frequency longitudinal plasma dispersion function. Since this study is concerned with anisotropic plasmas, a non-even plasma equilibrium distribution function is assumed with the direct result that more stable and unstable plasma modes corresponding to real and complex zeros of the plasma dispersion function are possible that has previously been considered. Also, for the longitudinal plasma wave problem, the Wiener-Hopf factorization of the fixed frequency longitudinal plasma dispersion function is presented and the coupled nonlinear integral equations for the Wiener-Hopf factors are studied. These Wiener-Hopf factors are required in the construction of the half range transport operator. / Ph. D.

A long hollow cylinder with five layers, subjected to a random thermal environment is analyzed. The random thermal environment includes the ambient air temperature, solar radiation and wind speed. The location of interest is Phoenix, Arizona. The governing differential equation is the so-called one-dimensional Fourier heat conduction equation in cylindrical coordinates. An implicit finite difference scheme is developed to obtain temperature responses inside the cylinder. Given the linear elastic behavior of materials involved, induced stresses and strains are evaluated at the end of each time step of the finite difference scheme. A statistical analysis is then carried out to determine the probability of failure of the propellant and hence the service life of the motor can be computed. / Ph. D.

The problem which, was explored in this study was: What are the perceptions held by doctoral gradates of their academic-professional and personal experiences related to the residency requirement? Five research, questions were posed to provide guidance for the collection of data for this study. They are described in detail in the summary and conclusions sections of this chapter. The overall purpose of this study was to provide a procedure for evaluating full-time residential study in a doctoral program as perceived by graduates. Specifically, the objectives were: 1) to define the purposes and activities of-the residency requirement in the College of Education at VPI&SU as articulated by the faculty and administrative staff; 2) to determine the graduates' perceptions of their academic, professional and personal experiences while fulfilling the residency requirement at VPI&SU; and 3) to compare and contrast the perceptions of the faculty and the graduates with respect to the residence requirement. / Ed. D.

The positron when formed as a result of nuclear decay process (β+) can interact with an electron resulting in a positronium formation (Ps). In the first part of this thesis the formation of positronium in benzene solutions containing various halogenated compounds was studied in the presence and absence of C₆F₆ additives. The observed I₂ values, which are indicative of the number of thermalized positronium atoms formed, showed a good correlation with the dissociative electron attachment parameters of the solute species. The formation and the reactions of Ps were found to be very sensitive to structural changes and phase transitions. Therefore, the positron annihilation technique was applied for studying systems such as micelles, liposomes and polymers which have found widespread applications in today's chemical industry. The micelle formation process was investigated in inverted micelles. A distinct cooperative effect of the solution resulting in abrupt changes in the number of thermal ortho-positronium atoms was observed and studied as a function of temperature, counter ion, length and structure of the hydrocarbon chain in the cationic and anionic parts of the surfactant molecules. The results are being discussed in terms of existing models. The thermotropic transition, which is an important parameter for all membranes and liposomes, was studied in sonicated dioctadecyldimethylam-monium chloride versicles (DODAC). The results obtained provide important information on fluidities and allow further assessments of cationic surfactant vesicles as membrane mimetic agents. The third application deals with the study of styrene-butadiene-styrene block copolymers obtained by casting in toluene, carbon tetra-chloride, ethyl acetate and methyl ethyl ketone. The temperature studies show the appearance of two distinct changes in the positron annihilation parameter λ₂ at -70°C and +85°C. They were attributed to the onset of motion of butadiene and styrene respectively. In addition two other abrupt changes in λ₂ were observed at -14°C and +10°C. The change at -14°C was observed in all films whereas the second at +10°C occurs only in films casted in poor solvents (ethyl acetate and methyl ethyl ketone). Their presence is discussed in terms of phase separation and morphological changes. / Ph. D.

The effects of room temperature tensile loading and five thermal loadings upon the development of transverse microcracks (TVM) in Celion 6000/PMR-15 graphite-epoxy laminates were investigated. Microcracks were observed using a replicating technique, microscopy and x-ray. The mechanical or thermal load at which microcracking initiates and the ply residual stresses were predicted using laminate analysis with stress and temperature-dependent materials. The TVM density as a function of tensile load was predicted using the multiple cracking theory proposed by Garrett, Parvizi and Bailey. Reasonably good correlation between theory and experiment was obtained for both the load at initial failure and the TVM density as a function of tensile load. It has been shown that TVM density and the load to initiate microcracking are functions of the type of loading and the laminate configuration. Generally, cross-ply laminates exhibit higher TVM density after thermal loading than do quasi-isotropic laminates, but the converse is true for tensile loading. Cross-ply laminates attain saturation TVM density prior to failure, but the TVM density of quasi-isotropic laminates continues to increase until failure. Edge effects have a significant influence on the development of TVM, and TVM present at the free edge of a laminate extend throughout the entire width of the laminate. <i>[Vita removed Feb. 15, 2011. GMc]</i> / Master of Science

The dependence structure of a stationary time series can be described by its autocorrelation function ρ^k. Consider the simple autoregressive model of order 1: y_t = αy_t-1 + u_t where α ε (-1, 1) is a fixed constant and the u_t's are i.i.d. N(O,σ²). Here ρ^k = α^|k|, k = 0, ± 1, ± 2, . . . . It can be argued that as α ranges from 1 to -1, the behavior of the corresponding AR(1) model changes from that of a slowly changing, smooth time series to that of a rapidly changing time series. This motivates a generalized AR(1) model where the coefficient itself changes stochastically with time: y_t = α(t)y_t-1 + u_t where α(t) is a random function of time. This dissertation gives necessary and sufficient conditions for the existence of a mean zero stochastic process with finite second-order moments which is a solution to the generalized AR(1) model and gives sufficient conditions for the existence of a weakly stationary solution. The theory is illustrated with a specific model structure imposed on the random coefficient α(t); α(t) is modeled as a strictly stationary, two-state Markov chain with states taking on values between 0 and 1. The resulting generalized AR(1) process is shown to be weakly stationary. Techniques are provided for estimating the parameters of this specific model and for obtaining the optimal predictor from the estimated model. / Ph. D.

An endo-1,4-β-D-glucanase (E.C. 3.2.1.4) and two exo-1,4-β-D-glucanases (exo-cellobiohydrolases I (D) and II, E.C. 3.2.1.91) have been purified to electrophoretic homogeneity from the extracellular culture filtrate of the imperfect fungus Trichoderma reesei QM 9414 grown on microcrystalline cellulose (Avicel). These three glycoprotein enzymes are the principal components of the cellulase system and constitute <95% of the extracellular protein produced by this organism when grown on cellulose or when incubated in the presence of sophorose (Q-β-D-glucopyranosyl (1->2) α-D-glucopyranose). The glucanases have been characterized with respect to a number of structural and enzymic properties. Neutral carbohydrate, predominantly mannose with some glucose, contributes 5, 21.2 and 14.1 percent of the weight of cellobiohydrolase I (D), cellobiohydrolase II and the endoglucanase, respectively. All three enzymes have a high proportion of acidic and hydroxylated amino acids, but much less of basic amino acids. Sedimentation equilibrium studies yielded the following molecular weights for the glucanases: cellobiohydrolase I (D) 53,220±1479; cellobiohydrolase II 54682±2683; endoglucanase 45,215±1483. Cellobiohydrolase I (D) is the most acidic (pH_I <3.8) of the three enzymes, whereas the endoglucanase and cellobiohydrolase II have isoelectric points of 4.7 and 5.6, respectively. All three lose activity when exposed to alkaline conditions, and the extent of alkali lability is directly related to carbohydrate content. This instability, as well as the low amino sugar content of the enzymes, indicates that the carbohydrate may be linked to the polypeptide via O-glycosyl bonds to serine or threonine residues. Among the three enzymes, the endoglucanase is most resistant to thermal inactivation retaining 70% of its initial activity on swollen cellulose after a 20 min preincubation at 70°. The optimum pH for activity is ca.4.9 for the endoglucanase and cellobiohydrolase II, whereas cellobiohydrolase I (D) has a broader pH range for activity, between pH 5.2 to 5.6. The mechanism of action of each glucanase was investigated by quantitative high performance liquid chromatographic analysis of the products arising from various cellulosic substrates as a result of enzymic action. Cellobiohydrolases I (D) and II produce predominantly (>90%) cellobiose from either oligosaccharides or cellulose. Cellobiohydrolase I (D) is unique among the three glucanases in its ability to cleave cellotriose. The endoglucanase reduces the viscosity of carboxymethylcellulose solutions with a specific activity of 116 (expressed as the change in specific fluidity/min/mg protein). This enzyme also possesses significant transglycosylation activity. When the three glucanases are combined in the proportion 60:25:15, cellobiohydrolase I (D): cellobiohydrolase II: endoglucanase (w/w) respectively, the resulting mixture exhibits activity identical to that of the crude enzyme preparation, with either swollen or crystalline cellulose as the substrate. All three glucanases are essential for the degradation of crystalline cellulose. Cellobiohydrolase I (D) crossreacts immunologically with cellobiohydrolases I forms A, B and C, but not with cellobiohydrolase II, justifying the designation of CBH I and II as isozymes rather than forms of the same enzyme. An enriched β-glucosidase preparation from the culture filtrate of Trichoderma reesei QM 9414 formed a single precipitin line when allowed to react with antiserum to the β-glucosidase previously purified from a commercial T. viride cellulase preparation. The absence of any spurs of nonidentity indicates that these two enzymes are structurally very similar. Lack of crossreactivity is observed between cellobiohydrolase I (D) and the endoglucanase purified during this investigation, but the latter crossreacts weakly with antiserum to cellobiohydrolase II. / Ph. D.

This study was conducted to serve as a basis for the making of administrative and policy decisions regarding student suspension. Selected personal, academic, and socio-economic characteristics of the 3,472 secondary students suspended by the Fairfax County (Virginia) Public Schools during 1976-77 were analyzed. In addition, selected organizational and demographic features were examined as they related to reasons for types, lengths, and incidence of the 5,504 suspensions administered. Data were obtained from school suspension reports, records, census, and property assessment information. An ex-post-facto, descriptive research design, including analysis of covariance, two-way analysis of variance, and the chi-square, was employed to determine the extent of relationships among variables selected. It was found that length of suspension varied significantly with reason and type. In-school suspensions were shorter than out-of-school suspensions. Unauthorized absenteeism was the most frequent suspendable offense. Significantly more suspensions than expected were reported per thousand students for all reasons at high minority enrollment and high student mobility rate schools. More students per thousand than expected were suspended longer and more often by these same schools as well as sub-school administrative organizations and small size schools. In-school suspension was used more often than expected by open plant design, medium size, and high student mobility rate schools, while out-of-school suspension was employed more often than expected by sub-school administrative organizations, small size, high student mobility rate, and high minority enrollment schools. Analysis of a random sample of 377 suspendees revealed that reasons for, lengths, incidence of suspension, and ethnic group of suspendees varied significantly with days absent. Those students suspended for attendance problems (unauthorized absence) were absent, on the average, more often than those suspended for any other reason while those suspended for drinking/drug offenses averaged fewer days absent. Average days absent ranged from 23.25 for students excluded one day to 32.90 for those suspended five days. In addition, students suspended more than one time were absent, on the average, more often than one-time suspendees. Black suspended students were absent an average of nearly six days more than white and other suspendees. Average days absent were greater for black suspendees than for whites and others. Standard achievement scores of suspendees varied significantly with reasons for, types, and incidence of suspension, in addition to grade level, sex, and ethnic group. The average standard achievement score for those students suspended for disruptive behavior was lower than the average score of those suspended for any other reason, while higher average achievement scores were attained by those excluded for drinking/drug offenses and insubordination. In-school suspendees’ average achievement score was nearly seventeen points higher than that of the out-of-school suspendees. One-time suspendees attained an average achievement score higher than the average scores for those excluded more than once. After adjustment for maturation, achievement scores of suspendees increased with grade level. The highest incidence of suspension was at the eighth and ninth grade levels. Average achievement scores for male suspendees were lower than for females. Female scores increased when adjusted for the effects of grade level, ethnic group, grade-point average, and parent(s)’ educational attainment level(s). Black suspendees’ average achievement scores were lower than whites and others. Recidivism was significantly higher than expected per thousand students for ninth/tenth grade, male, and black student suspensions. The repeat suspension rate for males was more than twice that for females; the rate for blacks was nearly five times the rate for whites and others. Recidivous suspensions for attendance offenses and insubordination were significantly greater than expected. Neither in-school nor out-of-school repeat suspension rates were significantly greater than one-time suspension rates. / Ed. D.