Pathogenic bacteria in foods are affected by several factors which may interact to enhance or inhibit microbial growth. <u>Staphylococcus aureus</u> 196E was inoculated into Brain Heart Infusion broth formulated with either 0.5, 4.5 or 8.5% NaCI, adjusted to pH 5.0, 6.0 or 7.0, and incubated aerobically at 12, 20 or 28°C. Mathematical models to predict the growth of <u>S. aureus</u> 196E were developed using a modified Gompertz function and response surface methodology. Each predictive equation required the estimation of only 23 parameters with a biological meaning. These models determined the significance of time, incubation temperature, sodium chloride (NaCI) concentration, and either pH or the logₑ of the undissociated acid concentration and any interactions on growth kinetics. Separate models were developed for the cases where pH was altered with either acetic acid, acetic acid plus sodium hydroxide, lactic acid and hydrochloric acid. All models adequately predicted the log growth of S. aureus 196E. Several interactive relationships between the independent variables upon population growth were significant. Predicted responses to multiple factor interactions were displayed with three-dimensional and contour plots. One model developed from a smaller subset of the growth data demonstrated that models could be produced with much less data collection. Generally, predictions of growth showed that acetic acid was more inhibitory to growth than lactic and hydrochloric acids. Furthermore, predicted and observed growth was slower or reduced when the undissociated acetic acid concentration was elevated at a specific pH. This methodology can provide important information to food scientists about the growth kinetics of microorganisms and prediction ranges or confidence intervals for growth parameters. Consequently, the effects of food formulations and storage conditions on the growth kinetics of foodborne pathogens or spoilage microorganisms could be predicted. / Ph. D.

This research examined the outsourcing decision for the logistics function of motor carrier transportation. A full factorial design was executed on a simulated transportation network to investigate how the efficiency of motor carrier transportation was affected by how it was structured (private/leased fleet versus contract carrier transportation) and the characteristics of the transportation activities. Transaction Cost Analysis (TCA) offered a useful theoretical framework for consideration of this make or buy decision by suggesting the independent variables of asset specificity, uncertainty, and frequency/volume. Seven two-part research hypotheses examined the relationships among the independent variables to gain a greater understanding of the factors which drive the make versus buy decision for motor carrier transportation. The major conclusions of this research are: 1) For the system modelled here, structure (private/leased versus contract carriers) and volume had the largest effects on transportation efficiency (mean shipment cost). 2) The results of this study indicated that there may be important factors within the nature of the “supplying” industry that impact the make or buy decision. This research provided strong support for TCA predictions and clearly demonstrated that TCA is a useful framework for understanding firms’ make or buy decisions. Because of the nature of the transportation industry (the high level of competition and the lack of a small numbers bargaining situation), the hypotheses in this research clearly indicated that a "buy" rather than a "make" decision was the most efficient alternative; this result is exactly consistent with TCA predictions. 3) For the system modelled here, higher fixed and per mile equipment leasing expenses (incurred in the operation of refrigerated trailers) caused refrigerated shipments to be more expensive than standard dry trailer shipments. That is, asset specificity (in this case, requirements for refrigerated trailer equipment) had a significant effect on shipment efficiency. / Ph. D.

This essay examines the persistent and penetrating role of philanthropy in the institutional life of Western Europe. Whatever knowledge has been gained in the collective survival of <i>Homo sapiens,</i> our species derives its authority over history from a purpose more significant than simply the survival of the fittest or the maximization of individual utilities. Our shared history expresses surprisingly consistent levels of organized compassion. Altruism and philanthropy, born of individual need, persist in collectivities. This is a study of public policy outcomes at those interstices where religious, political, and economic forces have taken shape, however transient, as human institutions or collectivities. The analysis yields a more comprehensive understanding of how public policy is made, particularly the unique comparative context of the new European Union. The individual and social choices made within this continuing process tell us a great deal about both the philanthropic impulse and the major institutions which comprise European life at the end of the twentieth century. The description of each important institutional intersection—religion and philanthropy in France, politics and philanthropy in Germany, and economics and philanthropy in England—is framed within the institution of social welfare. The modern European welfare system illustrates the acceptance of public obligations and commitments by the collective institutions of governance has altered over the course of time. Such adjustments, it seems, culminate in our own time in a fuller sense of collective and public responsibility for relationships. The role of altruism, charity, and philanthropy in that institutional shift—from a private to a public conscience—is at the heart of this essay. The "new tempered spirit" which can come to "comfort" the next century may be found in an unexpected intimacy between near and distant obligations as well as in the startling connectedness between ourselves as private individuals and ourselves as an increasingly diminutive portion of national and transnational institutions. The very limited human and institutional possibilities within what we now know as the modern nation-state may well come to an end with this century. The possibilities for new forms of both obligation and commitment to the endless variety of human needs and aspirations are unlimited. In much the same manner that the dissolution of the medieval life of old Europe permitted the discovery and construction of a new spirit of individual human potential, the dissolution of the political boundaries of contemporary Europe should permit the discovery and construction of a new spirit of human interdependence. / Ph. D.

Traditional natural language generation systems use a pipelined architecture. Two problems with this architecture are poor task decomposition and the lack of interaction between conceptual and stylistic decisions making. A revision architecture operating in a knowledge intensive environment is proposed as a means to deal with these two problems. In a revision system. text is produced and refined iteratively. A text production cycle consists of two steps. First, the text generators produce initial text. Second, this text is examined for defects by revisors. When defects are found the revisors make suggestions for the regeneration of the text. The text generator/revision cycle continues to polish the text iteratively until no more defects can be found. Although previous research has focused on stylistic revisions only. this paper describes techniques for both stylistic and conceptual revisions. Using revision to produce extended natural language text through a series of drafts provides three significant advantages over a traditional natural language generation system. First, it reduces complexity through task decomposition. Second, it promotes text polishing techniques that benefit from the ability to examine generated text in the context of the underlying knowledge from which it was generated. Third, it provides a mechanism for the integrated handling of conceptual and stylistic decisions. For revision to operate intelligently and efficiently, the revision component must have access to both the surface text and the underlying knowledge from which it was generated. A knowledge intensive architecture with a uniform knowledge base allows the revision software to quickly locate referents, choices made in producing the defective text, alternatives to the decisions made at both the conceptual and stylistic levels, and the intent of the text. The revisors use this knowledge, along with facts about the topic at hand and knowledge about how text is produced. to select alternatives for improving the text. The Kalos system was implemented to illustrate revision processing in a natural language generation system. It produces advanced draft quality text for a microprocessor users' guide from a knowledge base describing the microprocessor. It uses revision techniques in a knowledge intensive environment to iteratively polish its initial generation. The system performs both conceptual and stylistic revisions. Example output from the system, showing both types of revision, is presented and discussed. Techniques for dealing with the computational problems caused by the system's uniform knowledge base are described. / Ph. D.

A method is developed for analyzing the flexural-torsional and lateral-torsional buckling ("tripping") behavior of flanged stiffeners subjected to axial force, end moment, lateral pressure and any combination of these. The effects of cross-sectional distortion, postbuckling behavior of the plate (incorporated by considering the plate effective width), initial imperfections and plasticity are included. The method uses the Rayleigh-Ritz approach. Based on an assumed strain distribution, a displacement field is obtained for the tripping model, and the total potential energy functional is then derived. The strain distribution assumptions coincide with van der Neut's assumption. However, unlike the somewhat obscure differential equation approach given by van der Neut, this study provides a simple, clear, energy approach. Also the resulting method is applicable in the inelastic range, which is not possible with van der Neut's approach. Both the rigid web case and the flexible web case are studied. The effect of plate rotational restraint in the elastic range is accounted for. The method requires only four degrees of freedom and therefore the solution process is rapid. In order to verify the method in the elastic range, a number of sample stiffened panels are analyzed using the ABAQUS foote element program; the results are in quite good agreement. An inelastic tripping model is then developed based on the established elastic model, using deformation theory. Results obtained using the inelastic tripping method are shown to be in good agreement with experimental results, and to be more accurate than other methods. / Ph. D.

It has been said that inductively coupled plasma (ICP) is the panacea for the determination of metals in environmental samples. The ease of sample introduction for liquids coupled with excellent limits of detection of this spectrometric method provide the analyst with the ability to perform rapid, multi-element determination of most elements in the periodic chart. However, when samples have to be introduced in solid form such as suspensions of finely powdered material (slurries), in order to avoid lengthy extraction procedures and the use of strong acids, the method must be modified so that it can handle solid, often refractory material. Due to large size of the particles (≥ 10 μm), two problems are encountered: poor sample introduction efficiency in the conventional, concentric nebulizer; and poor vaporization efficiency at the argon plasma. The nebulizer tends to clog and a large fraction of particles is lost in the spray chamber due to their weight. The conventional argon plasma is not energetic enough to vaporize the analyte. In this project, a clog free Babington nebulizer was used. A surfactant/thickening agent, polyethylene oxide (PEO), was added to alter such physical properties of the slurry as surface tension, viscosity, and aerosol droplet size. Mixed gas plasma containing small amounts of nitrogen were used. Results showed that, by adding about 5 ppm of PEO, the emission intensity of an analyte increased significantly. Further experiments demonstrated that the signal enhancement resulted from an increase in the nebulizer efficiency brought about by a slight increase in viscosity of the slurry. The use of mixed gas plasma (Ar + 4% N₂) further improved the emission intensity. Temperature diagnostic measurements of such plasmas indicated that rotational and excitation temperatures are higher than those in a pure argon plasma. The improved temperature is believed to result from the higher thermal conductivity of molecular gases. Nitrogen added to the cooling gas works better than when added to the injector gas. Hydrogen does not seem to work as well as nitrogen, probably because its thermal conductivity is 14 times less than nitrogen. Further studies of the excitation temperature using Fe as the thermometric species, have been helpful in elucidating the mechanism of slurry vaporization in the plasma. There is evidence in this study that mass-transfer rather than heat-transfer is the limiting factor. With these improvements in the sample introduction and atomization cell, slurries having particle diameters up to 7 μm have been successfully analyzed. This value is 3 times larger than particles injected into pure Ar-plasma without a surfactant. The percent recovery of Ca, Fe, Mg and Pb, are comparable to that obtained from the same samples analyzed as solutions following acid digestion. / Ph. D.

Seventeen years have passed since Smith and Glass’s paper "Meta-analysis of Psychotherapy Outcome Studies" (1977) influenced how researchers integrated cumulative knowledge. The problem is that no meta-analyses have been found which compare psychotherapeutic methods to the use of Prozac in the treatment of unipolar major depression. Prozac was chosen, specifically, due to its reputation as a new, very effective anti-depressant. This study used a meta-analysis to compare three psychotherapies with medication: 1) cognitive therapy, 2) behavioral therapy, 3) cognitive-behavioral therapy, and 4) the prescription of Prozac. New methods of meta-analysis advocated by Rosenthal (1984) and Wolf (1986) were integrated with Smith and Glass’s (1977) Original approach to analyze the outcome research. The results indicate that Prozac is more effective than psychotherapy in the treatment of unipolar major depression. Psychotherapy results were statistically significant (p=.05) for the subjects as own control condition, but not for the control condition. In the subjects as own control group, cognitive and cognitive-behavior therapy were statistically significant (p < .05). The effectiveness of Prozac may have been caused in part by a selection bias of subjects or other factors outlined in the discussion. / Ph. D.

Freshly isolated protoplasts from pea leaves were used to investigate the responses of antioxidant enzymes to oxidative stress. Two cultivars, Progress (tolerant) and Nugget (sensitive), that have differing resistance with respect to oxidative stress at the whole plant level were used. Sulfite and the superoxide generating herbicide, paraquat, were used as the oxidants. Final sulfite concentrations during photosynthetic incubations ranged from 1.5 mM to 30.0 mM. During the polarographic estimation of photosynthesis, CO₂-dependent O₂ evolution did not decrease. At sulfite concentrations of 3.0 mM or less, light-dependent O₂ evolution increased and was probably due to a concomitant SO₂-dependent O₂ evolution. Photosynthesis determined as ¹⁴CO₂ fixation was not increased at these low concentrations of sulfite. Concentrations greater than 7 mM = sulfite inhibited photosynthetic ¹⁴CO₂ fixation. No difference in these responses was found between the two cultivars. At 0.1 µM paraquat, the relative resistance to oxidative stress was reversed compared to previous studies at the whole plant level. With the tolerant cultivar, activity of the plastid antioxidant enzyme, glutathione reductase, increased after a three-hour exposure. Changes in the steady state level of glutathione reductase protein, as judged by immunoblots, did not correlate with the observed changes in enzyme activity. No change in the de novo synthesis of glutathione reductase occurred over the same period as a consequence of paraquat application. A mechanism, unrelated to oxygen free radical scavenging, may contribute to the relative tolerance to low concentrations of paraquat. On the other hand, after an eight-hour exposure to 0.1 mM PQ in the presence of Gamborg’s basal salts, superoxide dismutase activity of Progress protoplasts was enhanced 288% above the preexposure levels while glutathione reductase activity decreased 70% and ascorbate peroxidase activity decreased 90%. The relationship of these changes to oxidative damage to the photosynthetic machinery remains to be assessed. / Ph. D.

Feeding trials.showed that ruffed grouse (Bonasa umbellus) performed well on diets containing 20% Christmas hollyfem (Polystichum acrostichoides) or mountain laurel (Kalmia latifolia), but diets containing 40% of these forages resulted in lower protein and energy intake and the Christmas hollyfem diet caused a loss of body mass. Grouse were not able to maintain themselves solely on evergreen leaves. Glucuronide excretion was greatest for the 40% mountain laurel diet. Ornithine conjugate excretion was greatest for a diet with 40% deciduous leaves. Sulfate excretion did not vary among diets. Intake rate of leaves was an asymptotic function of bite size when the density of bites did not limit intake. Intake rate of leaves decreased at plants densities < 322 plants/m2. The maximum intake rate of leaves was 25% of the intake rate of aspen buds observed in wild grouse (Huempfuer and Tester 1988). Intake rate of raisins was an asymptotic function of bite size and was 20 times greater than the intake rate of leaves. Ruffed grouse in the Southeast must forage for> 100 min/day under ideal conditions to satisfy energy requirements. / Ph. D.

This dissertation discusses a new approach to spline approximation. A periodic spline approximation 𝑓_M,m,N(x) = Σ_k=1^Nα_kΦ_M,k(x) to a periodic function 𝑓(x) is determined by requiring < Φ_m,j, 𝑓 - 𝑓_M,m,N > = 0 for j = 1,...,N, where the Φ_L,k's are the unique periodic spline basis functions of order 𝐿. Error estimates, examples and some relationships to wavelets are given for the case M - m = 2μ. The case M - m = 2µ + 1 is briefly discussed but not completely explored. / Ph. D.