This thesis develops models and associated Bayesian inference methods for flexible univariate and multivariate conditional density estimation. The models are flexible in the sense that they can capture widely differing shapes of the data. The estimation methods are specifically designed to achieve flexibility while still avoiding overfitting. The models are flexible both for a given covariate value, but also across covariate space. A key contribution of this thesis is that it provides general approaches of density estimation with highly efficient Markov chain Monte Carlo methods. The methods are illustrated on several challenging non-linear and non-normal datasets. In the first paper, a general model is proposed for flexibly estimating the density of a continuous response variable conditional on a possibly high-dimensional set of covariates. The model is a finite mixture of asymmetric student-t densities with covariate-dependent mixture weights. The four parameters of the components, the mean, degrees of freedom, scale and skewness, are all modeled as functions of the covariates. The second paper explores how well a smooth mixture of symmetric components can capture skewed data. Simulations and applications on real data show that including covariate-dependent skewness in the components can lead to substantially improved performance on skewed data, often using a much smaller number of components. We also introduce smooth mixtures of gamma and log-normal components to model positively-valued response variables. In the third paper we propose a multivariate Gaussian surface regression model that combines both additive splines and interactive splines, and a highly efficient MCMC algorithm that updates all the multi-dimensional knot locations jointly. We use shrinkage priors to avoid overfitting with different estimated shrinkage factors for the additive and surface part of the model, and also different shrinkage parameters for the different response variables. In the last paper we present a general Bayesian approach for directly modeling dependencies between variables as function of explanatory variables in a flexible copula context. In particular, the Joe-Clayton copula is extended to have covariate-dependent tail dependence and correlations. Posterior inference is carried out using a novel and efficient simulation method. The appendix of the thesis documents the computational implementation details. / <p>At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 3: In press. Paper 4: Manuscript.</p>

A series of experiments were conducted during 2005 and 2006 to evaluate five perennial grass species for forage yield and quality, steer performance and grazing capacity, animal intake, plant energy reserves and economic return under grazed conditions. In 1999, two 0.8 ha replicates each of Paddock meadow bromegrass (<i>Bromus riparius</i>Rehm.), Carlton smooth bromegrass (<i>Bromus inermis</i>Leyss.) and AC Knowles hybrid bromegrass (<i>B. riparius</i> x <i>B. inermis</i>) were seeded. In 2003, two 0.8 ha replicates each of AC Goliath crested wheatgrass (<i>Agropyron cristatum </i> (L.) Gaertn.), hybrid bromegrass, and Courtenay tall fescue (<i>Festuca arundinacea </i> Schreb.) were seeded. A long established stand of crested wheatgrass acted as the control pasture. For 2003 established pastures, AC Goliath crested wheatgrass (7515 kg ha-1) had greater (P<0.05) cumulative dry matter yield than hybrid bromegrass (3136 kg ha-1) during the 2005 grazing season. Average (2005-2006) crude protein (CP) was greatest (P<0.05) for hybrid and smooth bromegrass for 1999 established pastures at start and middle of period one. Control pastures had the greatest (P<0.05) neutral detergent fiber (NDF) mid-grazing period. Over 2 years, smooth bromegrass had greater acid detergent fiber (ADF) (P<0.05) than control pastures at the end of the grazing period one. Average (2005-2006) in vitro organic matter digestibility (IVOMD) was greatest for hybrid and meadow bromegrass (P<0.05) at the start of grazing period one. Control pastures (129 g kg-1) had lower CP levels at the start of the 2005-2006 (average) grazing period 1 (P<0.05) compared to species seeded in 2003. Control and hybrid bromegrass pastures had the greatest NDF and ADF levels at the start of grazing period 1 (2005-2006 average) while tall fescue pastures had the lowest (P<0.05) NDF and ADF levels. Over 2 years, control pastures had the lowest IVOMD at start of grazing (P<0.05). In 2006, hybrid and smooth bromegrass had greater etiolated re-growth than control pastures (P<0.05). In 2006, grazed plants seeded in 1999 had greater (P<0.05) etiolated re-growth than ungrazed plants. For 2003 seeded grasses, crested wheatgrass produced greater (P<0.05) etiolated re-growth than tall fescue and control pastures. Average daily gain was similar (P>0.05) for all 1999 and 2003 seeded grasses. Overall, bromegrasses seeded in 1999 produced greater animal grazing days (AGD) than control pastures (P<0.05). Total beef production (TBP) was greater (P<0.05) for hybrid and meadow bromegrass compared to the control. All species seeded in 2003 produced greater AGD (P<0.05) compared to the control. Crested wheatgrass produced greater (P<0.05) TBP than the control over both years of the study. The C33:C32 alkane ratio estimated greater DMI (P<0.05) for hybrid bromegrass (9.9 kg d-1) and control pastures (9.6 kg d-1) compared to crested wheatgrass (6.8 kg d-1) or tall fescue (6.8 kg d-1) during period 1 in 2006. Over 2 years, net return to labor, equity and personal draw was greater (P<0.05) for hybrid bromegrass ($91.24 ha-1) compared to the control (-$54.32 ha-1). For 2003 seeded pastures, all pastures generated positive returns over 2 years. Crested wheatgrass ($92.49 ha-1) had greater net return than control pastures (-$54.32 ha-1) (P<0.05). Finally, the results of this grazing study indicate beef producers can manage these grasses during the summer grazing season and maintain high levels of animal performance and pasture production. This study has demonstrated that bromegrasses, crested wheatgrass and tall fescue could work well in a complementary grazing system.

<i>In vivo</i> and <i>in vitro</i> studies on numerous types of blood vessels obtained from a variety of vascular beds and species have demonstrated that oxygen free radicals (OFRs) can evoke both vasodilation and vasoconstriction. Specific OFRs have been shown to elicit different and often times opposite effects on vascular smooth muscle. Therefore, this thesis attempts to define the vascular actions and mechanism of oxygen free radicals (OFRs) [superoxide anion (O₂^-), hydrogen peroxide (HO₂) and hydroxyl radical (OH)] on isolated rabbit aorta. This thesis will examine the role of OH in Ach- and nitroglycerin (NTG)-induced relaxation of isolated rabbit aorta. Superoxide anions generated by xanthine (X) plus xanthine oxidase (XO) produced concentration-dependent contractions of isolated rabbit aorta. The contractile response to O₂^- was completely abolished in preparations denuded of endothellum or pretreated with superoxide dismutase (SOD), a scavenger of O₂^-. The contractile response was reduced by indomethacin (I), a cyclooxygenase inhibitor. These results suggest that O₂^- mediated by vasoconstrictor arachidonic acid metabolites. Hydrogen peroxide generated by glucose and glucose oxidase produced contraction (low concentrations) and relaxation followed by contraction (high concentrations) in isolated rabbit aorta. The contractile response was abolished in the presence of catalase, a scavenger of H₂O₂ however the relaxant effect was exaggerated. Indomethacin markedly reduced the H₂O₂-induced contraction. Relaxation was completely prevented by de-endothelialization or pretreatment with N^G-monomethyl-L-arginine (LNMMA), an inhibitor of nitric oxide synthetase. These results suggest that H₂O₂ in large concentrations produces a biphasic response, relaxation followed by contraction. Relaxation is endothelium dependent and is mediated by endothelium-derived relaxing factor (EDRF), nitric oxide (NO). The contractile response is endothelium independent and is mediated by vasoconstrictor arachidonic acid metabolites of smooth muscle. Hydroxyl radicals generated by dihydroxyfumarate (DHF), ferric chloride (FeCl₃) and adenosine diphosphate (ADP) (DHF/FeCl₃-ADP) produced concentration dependent relaxations of NE-precontracted rabbit aorta. Mannitol (Ml) completely inhibited OH-induced relaxation. Relaxation was markedly reduced in aortic rings mechanically denuded of endothelium. The relaxant effect was reduced by an inhibitor of NO synthesis (LNMMA), by an inhibitor of guanylate cyclase (methylene blue), by an inhibitor of cyclooxygenase (indomethacin) and by an inhibitor of an ATP-sensitive K⁺ channel blocker (glyburide). These results indicate that OH produces relaxation that is endothelium-dependent and partially mediated by an endothelium-derived relaxing factor (NO), vasodilatory arachidonic acid metabolites and an ATP-sensitive K⁺ channel. We hypothesized that Ach-induced vascular relaxation is mediated by OH derived from the interaction of NO and O₂^-. To test this hypothesis we investigated the effect of Ach and NTG on NE-precontracted isolated rabbit aortic preparations in the absence or presence of scavengers of O₂^- (SOD), and OH (dimethylthiourea (DMTU) or mannitol or Garlicin). The OFR scavengers (SOD, dimethylthiourea, mannitol, garlicin and histidine) alone or the combination of SOD and DMTU markedly reduced Ach- or NTG-induced relaxation. However, the combination of histidine, (a ¹O₂ scavenger) SOD and DMTU completely abolished Ach-induced relaxation.

A series of experiments were conducted during 2005 and 2006 to evaluate five perennial grass species for forage yield and quality, steer performance and grazing capacity, animal intake, plant energy reserves and economic return under grazed conditions. In 1999, two 0.8 ha replicates each of Paddock meadow bromegrass (<i>Bromus riparius</i>Rehm.), Carlton smooth bromegrass (<i>Bromus inermis</i>Leyss.) and AC Knowles hybrid bromegrass (<i>B. riparius</i> x <i>B. inermis</i>) were seeded. In 2003, two 0.8 ha replicates each of AC Goliath crested wheatgrass (<i>Agropyron cristatum </i> (L.) Gaertn.), hybrid bromegrass, and Courtenay tall fescue (<i>Festuca arundinacea </i> Schreb.) were seeded. A long established stand of crested wheatgrass acted as the control pasture. For 2003 established pastures, AC Goliath crested wheatgrass (7515 kg ha-1) had greater (P<0.05) cumulative dry matter yield than hybrid bromegrass (3136 kg ha-1) during the 2005 grazing season. Average (2005-2006) crude protein (CP) was greatest (P<0.05) for hybrid and smooth bromegrass for 1999 established pastures at start and middle of period one. Control pastures had the greatest (P<0.05) neutral detergent fiber (NDF) mid-grazing period. Over 2 years, smooth bromegrass had greater acid detergent fiber (ADF) (P<0.05) than control pastures at the end of the grazing period one. Average (2005-2006) in vitro organic matter digestibility (IVOMD) was greatest for hybrid and meadow bromegrass (P<0.05) at the start of grazing period one. Control pastures (129 g kg-1) had lower CP levels at the start of the 2005-2006 (average) grazing period 1 (P<0.05) compared to species seeded in 2003. Control and hybrid bromegrass pastures had the greatest NDF and ADF levels at the start of grazing period 1 (2005-2006 average) while tall fescue pastures had the lowest (P<0.05) NDF and ADF levels. Over 2 years, control pastures had the lowest IVOMD at start of grazing (P<0.05). In 2006, hybrid and smooth bromegrass had greater etiolated re-growth than control pastures (P<0.05). In 2006, grazed plants seeded in 1999 had greater (P<0.05) etiolated re-growth than ungrazed plants. For 2003 seeded grasses, crested wheatgrass produced greater (P<0.05) etiolated re-growth than tall fescue and control pastures. Average daily gain was similar (P>0.05) for all 1999 and 2003 seeded grasses. Overall, bromegrasses seeded in 1999 produced greater animal grazing days (AGD) than control pastures (P<0.05). Total beef production (TBP) was greater (P<0.05) for hybrid and meadow bromegrass compared to the control. All species seeded in 2003 produced greater AGD (P<0.05) compared to the control. Crested wheatgrass produced greater (P<0.05) TBP than the control over both years of the study. The C33:C32 alkane ratio estimated greater DMI (P<0.05) for hybrid bromegrass (9.9 kg d-1) and control pastures (9.6 kg d-1) compared to crested wheatgrass (6.8 kg d-1) or tall fescue (6.8 kg d-1) during period 1 in 2006. Over 2 years, net return to labor, equity and personal draw was greater (P<0.05) for hybrid bromegrass ($91.24 ha-1) compared to the control (-$54.32 ha-1). For 2003 seeded pastures, all pastures generated positive returns over 2 years. Crested wheatgrass ($92.49 ha-1) had greater net return than control pastures (-$54.32 ha-1) (P<0.05). Finally, the results of this grazing study indicate beef producers can manage these grasses during the summer grazing season and maintain high levels of animal performance and pasture production. This study has demonstrated that bromegrasses, crested wheatgrass and tall fescue could work well in a complementary grazing system.

Bidens pilosa L. is a traditional Chinese herbal medicine of which was considered as a potential COX2 inhibitor and anti-inflammatory agent. The objective of this study is to discriminate the protective effect of aqueous extract of Bidens pilosa L. leaves (BPLAE) against TAA-induced live fibrosis using an animal model. The herb extracts were administrated via intraperitoneal injection once per week (1.25, 2.5 g/kg), and thioacetamide (200 mg/kg) was injected three times per week and the mice were sacrificed at week 4 and week 8, respectively. Immunohistochemistry staining, Hematoxylin-eosin (HE) staining, Sirius red staining were carried out to evaluate the pathological alterations of mouse livers; in addition, Western blotting was performed to measure the differential expression of £\-smooth muscle actin (£\-SMA) between different treatment groups (vehicle, week 4 and week 8). Hepatic hydroxyproline was also detected in order to compare difference in collagen formation of each group. The results showed that Bidens pilosa L. effectively reduced amount of hepatic hydroxyproline and £\-SMA protein in mice with fibrotic liver induced by TAA. Moreover, in histiopathological exam, the BPLAE treated mice demonstrated a lower collagen and £\-SMA expression, which indicated that BPLAE might reduce degree and severity of liver fibrosis in mice. In conclusion, these results suggested that BPLAE potentially against fibrogenesis in TAA- induced mice liver fibrosis. Additionally, we found that BPLAE might involve in the signaling pathway of MAPK (ERK1/ERK2), which reduced the phosporylation level of p44 but not p42. Further studies using cell base assay to confirm the inhibiting role of BPLAE against cell proliferation or migration is warrant.

This dissertation includes two chapters in the field of international finances about foreign exchange rate predictability and testing purchase power parity. In each chapter, we build the theory, methodology, and the empirical results to present the paper¡¦s construction. The first chapter, we studies whether the pure price inflation rate which is extracted from stock return can help us to test the relative of purchasing power parity in where Asian countries include Malaysia, Korea, Taiwan, Thailand, Hong Kong, and Singapore against the United States. The paper of Chowdhry et al. (2005) argue that relative PPP may not hold for the official price inflation rates which is constructed from consumer price indices, since relative price changes and other frictions cause price to be sticky. Thus, they use the Fisher equation and Fama-French three factors elaborately to build up a model on the nominal return of real risk-free asset to extract the pure price inflation rates. Their argument is supported in the case of Japan, Germany, the United States, and the United Kingdom. We are interested in the case of some Asian countries. So, this chapter, we extend the model and methodology of Chowdhry et al. (2005) to test the relative PPP for Asian countries. If our empirical evidence is firmly supported, it will be a strongly reconfirmed the elaborated idea of Chowdhry et al. (2005). In our study, the PPP rule is not supported for Asian countries since joint null hypothesis of a=0 and b=1 are rejected at all horizons except Taiwan at monthly horizon. The testing results by constrained seeming unrelated regression (SUR) and system equation in pooled data are similar to the tests of country-by-country. Therefore, we apply the methods of panel unite root from Im et al. (2003), Maddala and Wu (1999), and Pesaran (2007) to test the PPP doctrine, and it is strongly supported PPP for Asian countries. The second chapter, we extract the estimated data of pure price inflation by Chowdhry et al. (2005), and use the data to build up a nonlinear STR (smooth transition autoregressive) model by Granger and Ter&#x00E4;svirta (1993), then compare the performance of linear or nonlinear model of exchange rate predictability with random walk model in the United States, the United Kingdom, Japan, and Germany. This study has presented evidences that the extracted inflation rates offer a good predictability on the prediction of exchange rate for the United Kingdom and Germany. Those extracted data in which are calculated from the industry portfolio returns of stock market. The issue of series correlation in regression error does matter the estimated coefficients £]k, thus we estimate the simulation of Gaussian bootstrap distribution for testing variables with Newey West standard deviation in regression estimate. The empirical evidences show that the PPP doctrine affects the predictability performance of exchange rate change by the extracted inflation rates.

¡@¡@The purpose of this research is to employ the STAR model in discussing and analyzing the relationship between stock index and macroeconomic variables in Taiwan, Japan and Korea. ¡@¡@Monthly stock market index data is analyzed over the period January 1990 to December 2000, with the sample period from January 2001 to April 2005 being used in an out-of -sample forecasting exercise. The macroeconomic variables considered in this paper include money supply, consumer price index, industrial production index, interest rate and exchange rate. ¡@¡@The empirical results of Taiwan, Japan and Korea show that LSTAR & ESTAR model improve both the in-sample fit and out-of-sample forecast of the data over both the linear model alternative.

Peetre characterized local operators defined on the smooth section space over an open subset of an Euclidean space as ``linear differential operators'. We look for an extension to such maps of smooth vector sections of smooth Banach bundles. Since local operators are special disjointness preserving operators, it leads to the study of the disjointness structure of smooth Banach manifolds. In this thesis, we take an abstract approach to define the``smooth functions', via the so-called S-category. Especially, it covers the standard classes C^{n} and local Lipschitz functions, where 0≤n≤¡Û. We will study the structure of disjointness preserving linear maps between S-smooth functions defined on separable Banach manifolds. In particular, we will give an extension of Peetre's theorem to characterize disjointness preserving linear mappings between C^n or local Lipschitz functions defined on locally compact metric spaces.

Despite efforts by clinicians and scientists world-wide, coronary artery disease remains to be the leading cause of morbidity and mortality in industrialized nations. Development of a tissue engineered coronary by-pass graft with low thrombogenicity and immune responses, suitable mechanical properties, and a capacity to remodel to their environment could have a significant impact on the treatment of coronary artery disease. While many methods for the tissue engineering of blood vessels have been developed, one promising approach is the self-assembly method. Using autologous cells that produce an endogenous extracellular matrix (ECM), the potential for therapeutic success is high due to biocompatibility. However, despite these advantages, improvements can be made which will give the grafts an even higher rate of patency. This dissertation presents a study of the characterization of the biaxial mechanical properties of self-assembly tissue engineered blood vessels (SA-TEBV), as well as developing a framework for fabrication strategies of SA-TEBV. Native arteries are exposed to multiaxial mechanical loads, including (a pulsatile) blood pressure that causes the vessel to cyclically distend circumferentially, blood flow that induces a shearing load along the luminal surface, and an axial extending load; the latter is relieved upon excision, causing the vessel to retract. These mechanical loads introduce intramural wall stresses and flow induced wall shear stresses that play a key role in mechano-biological signaling and tissue homeostasis. Until now, the mechanical properties of SA-TEBV have only been characterized in the circumferential direction (i.e. burst pressure and circumferential elastic modulus). The objective of this work is to characterize the biaxial mechanical properties of SA-TEBV to quantify their mechanical behavior and local intramural stresses under physiological loading. The work will show that while the global mechanical response of the SA-TEBV is similar to that of native arteries (and potentially sufficient), the local intramural stresses (using the current fabrication techniques) differ greatly from native coronary arteries. Therefore, a novel approach to fabricate the self-assembly derived tissue sheets is developed and tested which utilizes biaxial mechanical stimulation to alter the microstructure, thereby controlling their mechanical response.

The engineering of human vascular grafts is an intense area of study since there is crucial need for alternatives to native vein or artery for vascular surgery. This current study sought to prove that a tissue engineered blood vessel (TEBV) 1mm in diameter could be developed from human smooth muscle cells and that endothelial progenitor cells (EPCs) could be cultured and used to endothelialize these grafts. This project had four specific aims: the isolation and characterization of EPCs, the seeding of a novel scaffold with EPCs and exposure to physiologic shear stress in vitro, the development of TEBV from human smooth muscle cells that are strong enough to implant in vivo, and the in vivo implantation of TEBV into the rat aortic model with a comparison of EPC seeded TEBVs pretreated with shear stress and unseeded TEBVs. The results yielded isolation of four EPC lines and a flow system design capable of seeding EPCs onto a novel scaffold with preliminary studies indicating that it is capable of exposing the EPCs to physiologic shear stress, although further studies require more optimization. The development of mechanically strong TEBV was highly successful, yielding TEBVs comparable to native vessels in collagen density and burst pressure, but with much lower compliance. Current implantation studies indicated that unseeded TEBV grafts implanted into the rat aorta without anticoagulation is highly thrombogenic. However, anticoagulation using Plavix may be capable of maintaining graft patency. These TEBVs did not rupture or form aneurysm in vivo and the future completion of the in vivo studies are likely to demonstrate the high potential of these grafts.