Dans un premier temps, nous abstenant de nous prononcer sur le statut ontologique du monde empirique, nous accédons au domaine transcendantal. Il s'agit alors de questionner l'évidence de l'ego-cogito et de thématiser l'intentionalité. Ce faisant, la méditation phénoménologique approfondit la thèse égologique du solipsisme transcendantal. Cependant le corps d'autrui fait toujours l'objet d'une expérience possible, Il est possible d'attribuer a cet autre le sens d'alter-ego puis d'en arriver à constituer une intersubjectivité transcendantale au moyen de l'apprésentation. Nous examinons ensuite les conséquences qu’entraine l'opération d'apprésentation, en nous attardant plus particulièrement à la constitution d'une nature objective et à la constitution d'une communauté intermonadique. Ce cheminement conduit à proposer la thématique de la culture comme problème phénoménologique.

Meprin A and meprin B are disulfide-linked, oligomeric metalloendopeptidases in renal brush border membranes. Meprin A contains 90-kDa subunits (α subunits) and is expressed in random-bred and some inbred strains of mice. Meprin B contains subunits of 110 kDa (β subunits) <i>in situ</i>, and the enzyme from C3H/He mice, a strain that does not express α subunits, has been characterized. Evidence from this and previous studies indicate that β subunits are expressed in all mouse strains. Meprins were characterized with regard to their glycosylation by lectin blotting. Both meprin A and meprin B bound the lectins concanavalin A and the erythroagglutinin from <i>Phaseolus vulgaris</i> indicating that both enzymes contain high mannose and bisected biantennary complex type oligosaccharides. However, meprin A, but not meprin B, bound the agglutinins from <i>Ricinus communis</i>, <i>Datura stramonium</i>, and the leukoagglutinin from <i>Phaseolus vulgaris</i>, indicating that complex-type N-glycosylation differs in these proteinases. Lectin blots of membrane proteins from C57BL/6 mice indicated that there were differences between adult male and female mice in the glycosylation (specifically in the complex type oligosaccharides) of the α subunit of meprin A. A marked degree of carbohydrate heterogeneity was observed in meprin A from males as compared to the enzyme isolated from female mice. Additionally, the data indicated that at least three of the ten potential glycosylation sites in the meprin α subunit are glycosylated. Overall, these studies expand our understanding of how estrogens affect glycosylation of meprin A. The oligomeric organization of the meprins was examined in brush border membrane fractions from a random-bred strain (lCR) and two inbred strains of mice (C57BL/6 and C3H/He). The random-bred strain contained three oligomeric complexes of approximately 390, 440, and 490 kDa as determined after sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-P AGE) in the absence of reducing agents. The subuβnits in all three oligomers were linked by disulfide bridges. Western blotting using anti-α monoclonal antibodies revealed that α subunits (90 kDa) were present in the 390- and 440-kDa complexes. Western blotting with polyclonal antibodies specific for the β subunit (110 kDa) revealed the presence of these subunits in the 440- and 490-kDa complexes. Electroelution of the individual oligomers followed by SDS-PAGE under reducing conditions confirmed that the 390- and 490-kDa molecules are homotetramers of α and β subunits, respectively, and that the 440-kDa complex is a heterotetramer composed of disulfide-linked α and subunits. C57BL/6 mice expressed both α and β subunits and contained tetramers composed of α₄ and α₂β₂. C3H1He mice expressed only the 110-kDa β subunits and the β₄ oligomer. This type of multimeric organization of covalently-linked subunits is unique for the known endopeptidases. Initial cloning of the mouse meprin β subunit revealed that the enzyme belongs to the recently described astacin family of metalloendopeptidases. The β subunit polypeptide had a molecular mass of 88 kDa as determined after SDSPAGE of brush border membrane proteins treated with glycosidases. Nucleotide sequencing, internal peptide sequences from the β subunit, and NH₂-terminal sequence analyses (39 residues) indicated that at the amino acid sequence level, mouse β is approximately 55 % identical to mouse , and 85 % identical to the rat β subunit. These and other studies indicate that α and β are closely related products of divergent evolution. Northern blot analyses of different tissues from C57BL/6 and C3H/He mice indicate that β subunit mRNA can be detected in kidney and intestine, in contrast to the α subunit which is only present in kidney tissue. Initial studies in mouse intestinal brush border membranes indicated that the characteristic latency of kidney β subunits may be absent in the intestinal enzyme. This observation may reflect activation of the mouse β subunit by trypsin in the intestinallumen. The activation of β in the kidney by trypsin-like proteinases is reminiscent of the activation of protein zymogens and may serve as a means of regulation of the proteolytic activity of the proteinase at the cell surface. / Ph. D.

This research is focused on the polymerization of 2-alkyl-2-oxazoline homopolymers and 2-alkyl-2-oxazoline containing copolymers with well-defined structures. In addition, the potential of selected materials as polymer blend compatibilizers was briefly evaluated. The polymerization of 2-alkyl-2-oxazoline was investigated with regard to the effects of initiator structures on molecular weight control and molecular weight distribution, living characteristics, and mechanisms and kinetics. The structure of initiators was shown to greatly affect the molecular weight control and molecular weight distribution of poly (2-ethyl-2-oxazoline). The living nature of poly (2-ethyl-2-oxazoline) in chlorobenzene initiated by benzyl iodide, benzyl chloride/NaI, or chloroethyl ethyl ether/NaI has been established by Mn-conversion plots and sequential monomer addition experiments. However, the molecular weight distributions of these polymers were not as narrow as Poisson distributions, Mechanistic and kinetic studies of 2-ethyl-2-oxazoline polymerizations suggested that, at very early stages of polymerization, the active species is covalent. After that very early Stage of polymerization, ionic species are present and the overall propagation rates increases. The rate determining step was found to be the initial propagation step(s) using benzyl iodide as the initiator, and initiation and/or the initial propagation step(s) in the case of iodobutane as an initiator. A kinetic study of 2-methyl-2-oxazoline polymerization in CD₃CN also indicated slower initiation than propagation rates using both butyl mesylate and butyl iodide as initiators. Based on the knowledge of 2-alkyl-2-oxazoline homopolymerizations, poly(2-alkyl-2-oxazoline) containing copolymers were prepared using macroinitiator methods, with poly(2-alkyl-2-oxazoline) being either the macroinitiator or the second component synthesized. Narrow distribution poly(dimethylsiloxane) oligomers terminated with benzyl chloride endgroups were prepared by living anionic ring-opening polymerization of hexamethylcyclotrisiloxane followed by termination with a benzyl chloride containing chlorosilane reagent. Cationic ring-opening polymerization of 2-ethyl-2-oxazoline using these macroinitiators in combination with NaI generated a series of well defined block copolymers. Poly(butyl vinyl ether) and poly(methyl vinyl ether) oligomers with Poisson distributions and precisely terminated on one end with a chloroethyl ether functional group were prepared by living cationic polymerization of alkyl vinyl ethers using a chloroethyl vinyl ether/HI initiating system with ZnI₂ as catalyst and terminated by lithium borohydride. The chloroethyl ether functional groups were used in conjunction with sodium iodide to polymerize 2-ethyl-2-oxazoline blocks. In order to insure effective initiation and to narrow the copolymer molecular weight and composition distributions, the chloride to iodide conversion was made prior to the addition of monomer. A series of these diblock materials was prepared wherein the molecular weight distributions ranged from 1.3 to 1.4. The bulk, solution and surface properties of these copolymers were investigated by NMR, DSC, XPS and surface tension measurements. Both types of materials described above are currently being utilized for studying the parameters important for steric stabilization of inorganic particles in polar media. A less defined series of materials was also prepared. Using poly(butyl vinyl ether-co-chloroethyl vinyl ether) random copolymers as: macroinitiators, 2-methyl-2-oxazoline was polymerized, resulting in poly(butyl vinyl ether-2-methyl-2- oxazoline) graft copolymers. Poly(2-methyl-2-oxazoline-ε-caprolactone) block copolymers were prepared using hydroxyterminated poly(2-methyl-2-oxazoline) as miacroinitiators. Poly(butyl vinyl ether-g-2-methyl-2-oxazoline) (PBVE-g-PMOX) or poly(2-methyl-2-oxazoline-b-ε-caprolactone) (PMOX-b-PCL) were screened as potential blend compatibilizers for poly(ε-caprolactam) (Nylon 6) and isotactic poly(propylene). Analysis of these blends by SEM indicated that PBVE-g-PMOX might function as a blend compatibilizer for Nylon 6/poly(propylene) blend while PMOX-b-PCL would not. / Ph. D.

A definition of an aircraft agility vector is given as the time rate-of-change of the applied forces acting on an aircraft and agility is characterized as being representable by instantaneous and integral time-scales. A unified framework for evaluating instantaneous and integral agility is developed based on the notion of a new dynamic model for aircraft motions. This model may be viewed as intermediate between a point-mass model, in which the body attitude angles are control-like, and a rigid-body model, in which the body attitude angles evolve according to Newton's Laws. Specifically, we consider the case of symmetric flight and construct a model in which the body roll-rate and pitch-rate are the controls. Accordingly, we refer to this new dynamics model as the body-rate model, (BRM). Instantaneous agility is presented as the locus of achievable agility vectors and the construction of such agility sets is demonstrated from aerodynamic and propulsive data for a modern jet fighter. Figures depicting this locus are displayed with indications of the limiting control. An integral performance flight problem is presented and subsequently solved via the optimal control theory. Agility metrics are suggested for this problem based on the transients which exist between the dynamics of the BRM and those of the point-mass model. Suggestions are also provided on the use of instantaneous agility sets and integral agility metrics in the design of aircraft and in performance comparisons of competing aircraft. / Master of Science

The objective of this thesis is to conduct research work on wideband characterization of the complex dielectric constant of low-loss dielectric materials used in multilayer structures. The materials include Pyralux®, a polymer, and Green Tape™, a low-temperature co-fireable tape ceramic (LTCC). The study is composed of three main tasks. First, the effects of operating temperature and relative humidity on the complex dielectric constant of these materials, at low frequencies, will be investigated. Next, the complex dielectric constant of these materials will be determined for high frequencies, under ambient conditions. Finally, lifetime tests will be performed in order to determine the effects of aging on the complex dielectric constant of these materials, at low frequencies. Since experiments will be performed at both low and high frequencies, both capacitor and T-resonator microstrip structures will be used. Analysis of the low frequency environmental test results indicate that both the dielectric constant and the dissipation factor of the polymer increase with both temperature and relative humidity. The results for the tape ceramic indicate that the dielectric constant and dissipation factor increase with temperature, but decrease with rising humidity. The results of the high frequency testing are compared to earlier experimentation in order to evaluate several test structures and techniques. Results of the aging experiments indicate that both the dielectric constant and the dissipation factor of the polymer are increasing over time. Conversely, both the dielectric constant and the dissipation factor of the tape ceramic are decreasing over time. / Master of Science

In this thesis, the miscibility behavior of blends of polypropylene (PP) and poly(l-butene) (PB1) will be reexamined. The driving force for this study is the fact that contradictory conclusions on this subject exist in the literature. In this thesis, the glass transition behavior, morphology, spherulite growth rate and melting behavior of PP/PB1 blends with different molecular weights and tacticities have been investigated. Dynamic mechanical analysis on the melt blends of isotactic polypropylene and poly(1-butene) (it-PP/it-PB1), made of commercial high molecular weight materials, indicates a single but broad, composition dependent glass transition temperature. Crystallization studies of the a phase of it-PP in these blends show that the spherulitic growth rate of it-PP decreases with increasing it-PBl content. The melting behavior of the it-PP also depends on blend composition. However, polarizing optical microscopy reveals morphologies strongly indicating phase separation in these blends. These seemingly conflicting results are explained by further studies performed on the blends of the same it-PP with an atactic poly(i-butene) of lower molecular weight and blends of the atactic poly(1-butene) with an atactic polypropylene. From studies of the glass transition behavior, morphology and growth rate, it was found that the it-PP and the at-PP are definitely miscible with the low molecular weight at-PB1. Since commercial isotactic polypropylene and isotactic poly(1-butene) always contain a certain amount of low molecular weight fractions, it can be concluded that the single composition-dependent T _g, the growth rate depression and the changes in the melting behavior of the it-PP/it-PB1 blends arise from the miscibility of the low molecular weight fractions (both isotactic and atactic) of the it-PB1 and it-PP. Theoretical calculations utilizing the Flory-Huggins-Hildebrand theory (7) supports the above conclusions and suggests the phase separation phenomena in the it-PP/it-PB1 blends is caused by the high molecular weight it-PB1. / Master of Science

A high-fat bologna was formulated to contain 30%fat/10% added water (AW). Three low-fat treatments were formulated to contain 10%fat/30%AW. Lean and fat trim for the low-fat treatments (2, 3, and 4) were combined and minced before massaging intermittently (10 min on/20 min off) for 0, 2.5 and 5.0 h, respectively. Massaging improved (P<0.05) sensory cohesiveness scores and decreased particle definition. However, the high-fat control was the most cohesive, firmest and least juicy (P<0.05). Instron Texture Profile Analysis indicated that massaging increased cohesiveness (P<0.05) and tended to increase springiness. There were no differences (P>0.05) in hardness or fracturability among the low-fat treatments. The high-fat bologna was the hardest, least cohesive, and least springy P<O.05. / Master of Science

Many digital display devices allow only a limited number of colors to be displayed concurrently. Digitized color images typically contain several hundred to several thousand different colors. If these color images are to be viewed on displays with a limited color palette, the number of colors used to represent the image must be reduced to satisfy the display limits. This process is known as color quantization and is a special case of vector quantization. It has been shown that images containing large numbers of colors can be quantized to a very small color palette with little degradation in visual quality. This thesis presents a new algorithm, based on Heckbert's original median cut procedure, for creating near-original quality images using a small color palette. We have found that slight changes to Heckbert's original algorithm yield dramatic improvements in quantizer performance. The color quantization problem is considered in two parts: the selection of the optimal color palette, and the optimal mapping of each image pixel to a color from the palette. The method to be described is an image dependent quantizer in ROB color space. Resulting image quality is measured both subjectively and with a squared error metric. / Master of Science

<u>Bifidobacterium</u> spp. are anaerobic, Gram-positive, nonmotile bacteria that are a major component of intestinal microbiota. They are potential indicators of human fecal pollution in shellfish harvesting waters. In addition, <u>Bifidobacterium</u> spp. are used as supplements in dairy products. These bacteria are easily injured and it is important to have methods that will recover all cells (injured and uninjured) present in water and food samples. The objectives of this research were to develop a repair detection (RD) procedure to be used with VPI's anaerobic roll tube apparatus for improving the recovery of Bifidobacterium and to compare this method with existing enumeration methods. <u>Bifidobacterium adolescentis</u> cells were injured by exposure to pond water. Cells were enumerated using a modification of Human Bifid Sorbitol Agar (MHBSA). MHBSA was modified by substituting phenyl red for bromocresol purple and adding methylene blue as an indicator of oxidation/reduction. / Master of Science

Does the way a question is asked affect the answer given? This thesis looks at this question from two perspectives. First, using contingent valuation data for water quality in the Monongahela River in Western Pennsylvania, an analysis is performed to test for differences in responses across four different formats of the willingness-to-pay question. This analysis shows that the question format has some systematic relationship with the valuation responses given. Specifically, iterative bidding games with high starting points lead to higher willingness-to-pay values than other formats. This result appears to arise from information relayed to the respondent from the question format. That is, since the bidding begins at a high value the respondent interprets that information as a cue to what the value of the commodity should be. The four different question formats are then re-interpreted in a referendum context. Referendum campaigns can be characterized by the amount of information provided to the voters and the degree of focus of that information. For example, some referendum campaigns give the voters a great deal of data, and that data all gives a consistent message. Other campaigns provide very little information for the voters to use in their decision. By transforming the willingness-to-pay data into a discrete-choice format, referendum models are simulated. Then, an analysis shows how the characteristics of the information content affect the vote. Also, the value of the median voter is calculated. This median shows the value at which the referendum just passes. This analysis shows that the campaign associated with the high starting point bidding game yields that highest percentage of yes votes and the highest median voter value. / Master of Arts