VictorJuiz/thesis huggingface dataset:
On the aminergic innervation of locust (Locusta migratoria) salivary glands

This study is a characterization of the aminergic innervation of the salivary glands of the locust, Locusta migratoria. The salivary glands of Locusta are innervated via one pair of tyrosine hydroxylase-like positive cells (SN1) and one pair of serotonin-like positive cells (SN2) whose somata are located within the suboesophageal ganglion. Serotonin and dopamine induce dose-dependent elevations of cyclic AMP levels in the salivary glands. The rank order of potencies of serotonergic and dopaminergic antagonists suggest the presence of a receptor similar to vertebrate 5-HT$\sb2$ and vertebrate D$\sb1$ receptors. The increases in cyclic AMP levels are mimicked by neural stimulation of the salivary nerve which can be partially inhibited by the dopaminergic antagonist SCH-23390, and by the serotonergic antagonist spiperone. Neural stimulation of the salivary nerve leads to time- and frequency-dependent eievations of cyclic AMP levels in the glands that can be partially inhibited by SCH-23390. Uptake transporters for serotonin and dopamine are associated with the salivary glands. The uptake of ($\sp3$H) serotonin is Na$\sp+$-dependent and is composed of high- and low-affinity components. The uptake of ($\sp3$H) dopamine is Na$\sp+$-independent. The efflux of ($\sp3$H) serotonin and ($\sp3$H) dopamine from the salivary glands is Ca$\sp{2+}$-dependent and occurs in response to stimulation of the salivary nerve and to treatment with high-K$\sp+$ saline. Neural stimulation of the maxillary nerve on the SOG results in phase locked SN1 activity at low stimulatory frequencies but not at high. Perfusion of desheathed suboesophageal ganglia with acetylcholine, cholinergic agonists, and octopamine leads to enhanced activity of either SN1 or SN2, or both. Perfusion with either dopamine, serotonin, glutamate or GABA has no apparent effect on salivary neuron activity. A comparative study of salivary gland innervation in the cockroach, Periplaneta americana, and the stick insect, Carausius morosus, was performed. Tyrosine hydroxylase-like immunoreactivity of the SOG of Periplaneta and Carausius, reveals a dopaminergic SN1 pair in both animals. Serotonin-like immunoreactivity of the SOG and salivary glands of Carausius reveals a serotonergic SN2 pair. A phylogenetic analysis using neuroanatomical and neurophysiological data for Locusta, Carausius and Periplaneta, suggest that Phasmatodea and Orthoptera are sister taxa.
Applying 2D NMR methods to the structural elucidation of complex natural products

By means of a combination of 2D NMR experiments, namely HMQC, HMBC, COSY, TOCSY, NOESY and ROESY, structural determinations and spectral assignments have been completed for a number of natural products and compounds derived from natural products. Examples bearing certain unusual or interesting features are discussed in detail. Three alternative but less widely used techniques are evaluated in terms of their contributions to spectral presentation. HSQC has resolution and sensitivity advantages over HMQC, and coupled HSQC spectra are particularly suitable for the determination of $\sp1$H multiplet patterns, aiding stereochemical assignments. HETCOR and FLOCK provide superior $\sp{13}$C resolution and their sensitivity disadvantages can be minimized by means of a microprobe/microtube combination. Furthermore, linear prediction is a reliable time-saving data processing technique that can enhance the sensitivity of 2D NMR spectra.
Regulation of the cell cycle in astrocytomas

To better understand the molecular mechanisms of astrocytoma proliferation and differentiation, the expression and activity of cell cycle regulatory factors were studied in astrocytoma cell lines. The expression of cyclins, cyclin-dependent kinases (CDKs) and cyclin-dependent kinase inhibitors (CKIs) was studied in a panel of astrocytoma cell lines. One cell line, U343MG-a (U343) demonstrated increased expression of cyclins and CDKs in comparison to other cell lines. U343 lacks the expression of p16$\sp{Ink4\rm a}$ and undergoes a G1 cell cycle arrest in response to the differentiation agent retinoic acid (RA). RA also increases the expression of CKIs p21$\sp{Cip1}$ and p27$\sp{Kip1}$ in this cell line and leads to the formation of bipolar cell processes and rearrangement of cytoskeletal intermediate filaments and microfilaments. When p21 and p27 were overexpressed in these cells using the tetracycline expression system U343 cells were growth arrested and became large and flat without process formation. Co-treatment of these tetracycline responsive cells with RA, however, led to a morphological change reminiscent of differentiated astrocytes, a phenotype not seen in cells treated with RA or CKI induction alone. Restoration of p16 expression in U343 cells also failed to induce phenotypic alteration resembling differentiation, unless co-treated with RA. These studies demonstrated that a CKI-growth arrest signal is insufficient to trigger differentiation in U343 cells, but it does cause a unique "flat cell" phenotype. U343 cells require cell cycle arrest and a differentiation signal to phenotypically resemble mature astrocytes. Interestingly, induction of CKIs in U343 cells also leads to the alteration in the expression and activity of pRB/E2F family members. Furthermore, we show that the cell cycle block mediated by CKIs can be overcome by overexpression of E2F factors, demonstrating that restraint of E2F activity is a critical event in CKI-mediated cell cycle arrest. These data demonstrate that CKI's regulate cell growth through a discrete pathway involving pRB and E2F factors and that malignant astrocytoma cell proliferation can be controlled by manipulation of this pathway. Furthermore, we demonstrate that when this pathway is activated by induction of CKI's, the cells become more responsive to a differentiation signal. Restoration of cell cycle control by gene transfer of a CKI and administration of a differentiation agent such as retinoic acid may be a novel strategy to treat astrocytomas in vivo.
The effects of obstructive sleep apnea on blood pressure

Several epidemiological studies have identified obstructive sleep apnea (OSA) as a risk factor for systemic hypertension, but a direct etiologic link between the two disorders has not been established definitively. Furthermore, the specific physiological mechanisms underlying the association between OSA and systemic hypertension have not been identified. The purpose of this study was to use a canine model of OSA to systematically examine the effects of OSA on daytime and night-time blood pressure (BP). In addition, this model was used to determine the long-term effects of sleep apnea on the acute responses to airway occlusion during sleep. Four dogs were studied during a control period before induction of OSA, during a period of OSA (of 83-133 days), and following cessation of OSA. After completion of the OSA protocol, the dogs were re-studied on a sleep fragmentation protocol to determine the impact of sleep disruption without OSA on the acute responses to airway occlusion. OSA resulted in acute transient increases in night-time BP to a maximum of 13.0 $\pm$ 2.0 mm Hg (mean $\pm$ S.E.); and eventually produced sustained daytime hypertension to a maximum of 15.7 $\pm$ 4.3 mm Hg. In contrast, recurrent arousal from sleep without airway occlusion caused night-time hypertension but did not result in daytime hypertension. In addition, OSA and sleep fragmentation both resulted in progressive lengthening of the time to arousal in response to acute airway occlusion (all p values $<$0.02), and in greater arterial oxygen desaturation (p $<$ 0.05), peak inspiratory pressures (p $<$ 0.003), and surges in maximum systolic and diastolic BP during airway occlusion (p $<$ 0.01). There were no differences between the changes observed during OSA and during sleep fragmentation. Thus, the impact of OSA on the acute responses to airway occlusion during sleep is primarily the result of the associated sleep fragmentation. The demonstration that OSA can lead to the development of sustained hypertension has considerable importance, given the high prevalence of both disorders in the population.
Optimization of nonhomogeneous facesheets in composite sandwich plates

Minimum weight design is an important criterion in aircraft and spacecraft because it allows either an increased pay-load or higher performance. As a result, the use of composite sandwich panels has grown due to their light weight and high rigidity. In order to further increase the efficiency of these structures, designers have used different materials in different shapes in the facesheets and in the core. One of the most recent innovations has been the use of a uniform net of carbon fibre/epoxy as the facesheets. In the present study, the optimal design of sandwich plates with heterogeneous, facesheets is treated. The plate mass is minimized, considering the first natural frequency and certain failure loads as constraints. Weight reduction is obtained by defining a nonuniform distribution of composite material in the facesheets. Initially, the facesheets are assumed to be constructed of composite strips in a regular pattern. During the optimization process, both the widths of the strips and the spacing between them are varied to decrease the amount of material used. Such a design is conceptually straightforward to manufacture and, therefore, would lead to improved performance with little cost penalty. In order to solve this problem, it is first necessary to develop a computer code to determine the natural frequencies and the stresses in these plates. The bending and vibration problems for sandwich plates with heterogeneous facesheets are solved using the Ritz Method in conjunction with the assumptions formulated by Reissner for sandwich plates. Since the sandwich plate considered in this study has facesheets constructed of nets and the computer code was developed to analyse laminates with heterogeneous continuous layers, it was necessary to use a procedure to approximate the nonuniform net as a smoothed orthotropic heterogeneous continuum. The smoothing process is accomplished using the theory of homogenisation and the material coefficients were calculated using the Finite Element Method. Two approaches were considered to define the design variables of the problem: an independent design approach, in which the facesheets are discretized into regions with uniform design parameters; and a reduced basis formulation, in which the design is specified by a linear combination of orthogonal basis functions. This study solved the problem proposed. It has been demonstrated that variation in density is important and can lead to significant design improvement. Across of the face of the optimally designed plate, the density varies by a factor of 9. Also, the problems solved showed that the mass of the facesheets can be reduced up to 50%.
Crystal structure and catalytic mechanism of the catalytic domain of the ß-1,4-glycanase Cex

Cellulose-degrading microorganisms secrete a number of glycosyl hydrolases to degrade plant cell walls, the most abundant and renewable source of biomass. The bifunctional xylanase/cellulase ($\beta$-glycanase), Cex, secreted by the bacterium Cellulomonas fimi is an example of glycosyl hydrolases (family 10). This enzyme releases a disaccharide unit following the hydrolysis of its polysaccharide substrate. By analogy with lysozyme, the catalytic mechanism would proceed through an oxocarbonium ion-like species as the catalytic intermediate. However, recent evidence supports the existence of a covalent intermediate in the Cex catalytic mechanism; for example, cleavage of 2$\sp{\prime\prime},4\sp{\prime\prime }$-dinitrophenyl-2-deoxy-2-fluorocellobioside (2FDNPC) by Cex produces a covalent 2-fluorocellobiosyl-enzyme complex. A covalent 2-deoxy-glycosyl-enzyme intermediate has also been speculated to occur in the hydration of glycals by glycosyl hydrolases. In the present work, structural details of the catalytic domain of Cex (cex-cd), unliganded and with covalently complexed disaccharides, give insights into its folding motif, its active site structure and its mechanism of catalysis. This thesis reports the high resolution (1.8 A) crystal structure of cex-cd which is determined by the classical method of isomorphous replacement using heavy atoms. The main architecture of cex-cd consists of an elliptic ($\beta/\alpha$)-barrel with eight $\beta$-strands forming the core. The active site is almost exclusively composed of conserved residues, suggesting a similar substrate recognition and catalytic mechanism among enzymes of family 10 of glycosyl hydrolases. The structure of cex-cd determined in the presence of 2FDNPC reveals a fluorocellobioside molecule at the carboxy-terminal end of the ($\beta/\alpha$)-barrel, which delimits the active site of the enzyme. This ligand is attached to the nucleophile Glu233 by a covalent link of $\alpha$-configuration, which is consistent with a double displacement catalytic mechanism. In addition, a short exposure of cex-cd to the glycal cellobial leads to a 2-deoxy-cellobiosyl-enzyme covalent complex. From the structure of these complexes, seven structural characteristics of the covalent glycosyl-enzyme catalytic intermediate are identified. These studies help to understand catalysis by retaining $\beta$-1,4-glycosyl hydrolases and may be useful in the future for rational design of inhibitors.
Are metaphors elliptical similes?

The comparison theory holds that metaphors are elliptical similes, so that "Sam is a pig" is an ellipsis for "Sam is like a pig" (Fogelin, 1988). Glucksberg and Keysar (1993), and others, have argued against this theory by claiming that metaphors are "stronger" than similes. Their argument rests on the existence of conventions for strengthening a comparison by converting it from a simile to a metaphor. If one says "Sam is like a pig," another speaker can correct the claim by saying "well, I think Sam is a pig." Likewise, a comparison can be weakened by being converted from a metaphor to a simile. If one says "Sam is a pig" another speaker can say "well, I think Sam is like a pig." This thesis argues that these conventions for correcting a speaker do not ensure that metaphors are stronger than similes when used on their own. The results of the first four experiments indicate that metaphors are indeed judged to be stronger than similes in corrective situations. In particular, relative to speakers of similes, speakers of metaphors are seen to be attributing more properties to the tenor (e.g., "Sam" in "Sam is a pig"), expressing stronger attitudes, and suggesting that the tenor possesses a particular property to a greater extent. However, the results of a further four experiments indicate that these differences can be reduced when metaphors and similes are used on their own. Moreover, a ninth experiment indicated that people do not prefer to use metaphors over similes to summarize large numbers of properties, which also suggests that metaphors do not involve more properties than similes. An additional two experiments revealed that people can verify the relevance of a broad range of properties for metaphors and similes equally quickly, suggesting that metaphors are not more strongly associated with a wide range of properties than are similes. The results of all of these experiments are consistent with the comparison theory: metaphors do function as elliptical similes.
Bayesian estimation of discrete duration models

This thesis is comprised of three chapters which discuss Bayesian estimation of discrete time duration models. The first chapter presents the multiperiod probit model and discusses estimation with a Gibbs sampler with data augmentation. As an empirical illustration, the multiperiod probit model is used to estimate a duration model using employment duration data for New Brunswick, Canada. The results from Bayesian estimation are compared with maximum likelihood estimation of a logit hazard model. Bayesian estimation of a model with unobserved heterogeneity is shown to be a simple extension of an estimation of a model with no unobserved heterogeneity. The second chapter discusses parametric and nonparametric specifications of duration dependence. I then propose an alternative to these specifications that can capture the features of both specifications. I employ a Shiller smoothness prior to restrict the curvature of the parameters in the nonparametric duration dependence specification and hence put restrictions on the shape of the baseline hazard. The smoothness prior is used to help 'filter' the 'noise' that commonly appears in estimates of the baseline hazard. The methods are illustrated in an empirical exercise with employment duration data from the Canadian province of New Brunswick. The estimates with the smoothness prior are compared with the competing alternatives to modelling duration dependence. In the third chapter a Bayesian estimator for a discrete time duration model is proposed which incorporates a nonparametric specification of the unobserved heterogeneity distribution through the use of a Dirichlet process prior. This estimator offers distinct advantages over the nonparametric maximum likelihood estimator (NPMLE) of this model. First it allows for exact final sample inference. Second, it is easily estimated and mixed with nonparametric specifications of the baseline hazard. An application of the model to employment duration data from the Canadian province of New Brunswick is provided.
Surface grafting of poly(ethylene glycol) in the presence of cells, a strategy to construct double-layered mammalian cells containing microcapsules

Surface grafting of poly(ethylene glycol), (PEG) was performed in close proximity to live PC12 cells while maintaining a sufficient number of viable cells in vitro. The purpose of the study was to improve the biocompatibility of microencapsulated cells by performing a surface graft and constructing a double layered microcapsule by manipulating the surface chemistry. Several hydrogels that contain reactive primary amines intended for the inner-layer were synthesized. Poly(acrylic acid-co-acrylamide-co-methyl methacrylate-co-vinylamine) was synthesized via Hofmann degradation with a maximum of 8 mole% vinylamines but it was mechanically insufficient. On the other hand, crosslinked poly(acrylamide-co-vinylamine) films, synthesized in a similar manner, had 50 mole% primary amine on the surface and were reacted with tresylated PEG to form a modified outer layer: XPS showed $\sim$2% of amines coupled with PEG. Covalent attachment of PEG occurred in addition to the passive physical adsorption which was also observed by mixing the film with non-activated PEG. To evaluate if the reaction could be applied to microcapsules, the effect of the reaction on the cells was studied by model experiments using crosslinked films because of the difficulty in fabricating the amine containing polymers into microcapsules. The cells retained $\sim$80% viability (trypan blue) while seeded on top of films which being reacted with 10 $\mu$mole/g tresylated PEG in 0.1 M (N-tris hydroxymethyl-2-aminoethane sulfonic acid) buffer for 2 hours at 37$\sp\circ$C. Surprisingly, the reaction itself was not considered to be the major cause of cell death. Rather it appeared that the combined effect of the cytotoxicity of the leaving groups and the changes in osmotic pressure were more significant. Consistent with these observations, the activity of cells in unreactive poly(hydroxyethyl methacrylate-co-methyl methacrylate) microcapsules did not decrease after 2 hours of incubation with activated PEG according to the MTT (3-(4,5-dimethylthiazol-2-yl)-2, 5-diphenyl-tetrazolium bromide) assay. Surface modifying the microcapsules was considered possible by optimizing the reaction conditions so that the diffusion of the tresyl group into the capsule would be limited to keep the capsule core concentration $<$20 $\mu$mole/g. Novel microcapsules containing live cells with different surface and bulk composition may be created by further refinement of this study.
Language and society, studies of guandao/gongchi and corruption in post-Mao China

The aim of this thesis is to investigate how societal changes and particularly two types of corruption are reflected in the emergence and development of neologisms in post-Mao China. In order to accomplish this goal, two groups of neologisms are studied. One group of neologisms examined is that connected with speculation and profiteering. The other group consists of neologisms associated with wining and dining at public expense. Specifically, this study analyzes new expressions and terms which contain the following two key Chinese characters: (1) dao (to speculate) as in the phrases daoye and guandao and, (2) chi (to eat) as in the phrase gongkuan dachi-dahe or gongchi. Other relevant new terms which do not contain those two characters but fall into one of the two categories are also included. This study does not examine these neologisms just from a lexicographer's point of view. It goes beyond the purely linguistic phenomena in order to examine them in their historical and contemporary socio-political context.
The characters of depth-zero representations of Sp¦4(F)

The harmonic analysis of a p-adic group G(F) with Lie algebra g(F) studies two families of distributions on the space $C\sbsp{c}{\infty}({\bf g}({\rm F})\sb{tn})$ of Schwartz functions supported by topologically nilpotent elements: the Fourier transform of regular orbital integrals$$f\to{\rm I}\sb{G}(X, \ f) := \int\sb{T({\rm F})\\ G({\rm F})}\ \ f(Ad(x\sp{-1})X)dx$$and characters of supercuspidal representations $\pi$ of G(F)$$f\to{\rm I}\sb{G}(\pi, f \circ\log) := {\rm Trace}\ (\pi(f\circ\log)).$$ Although it is widely believed that the two finite-dimensional vector spaces spanned by these distributions are closely related, only in a few instances is it known how to write elements from one space as a linear combination of elements from the other. This thesis produces such a relationship for certain representation of Sp$\sb4$(F); specifically, for certain supercuspidal, depth-zero representations $\pi$ of Sp$\sb4$(F) we find $H\in sp\sb4$(F) and integers $c\sb{H}(\pi)$ such that$${\rm I}\sb{G}(\pi, f\circ\log)=\sum\sb{H}c\sb{H}(\pi){\rm I}\sb{G}(H, \ f)$$whenever $f\in C\sbsp{c}{\infty}({\bf g}(\rm F))$ has small support. Our technique makes use of recent work of L. Morris concerning certain filtrations of g(F) as well as the generalised Springer correspondence on ${\bf g}({\rm I\!F}\sb{q}).$ Along the way we deal with some geometric questions which refer to the study of affine Springer fibres by Bernstein, Kazhdan and Lusztig. We also study the stability of certain sums of characters and produce identities relating the values of Shalika germs at unramified and ramified points.