Despite the squat jump's intriguing dynamical properties and prevalence in athletics, there is a lack of information regarding the comprehensive functional role of muscles during the squat jump. To increase our understanding of the strategies the human body uses in accelerating joints and contributing energy to body segments, we incorporated experimental data from trained collegiate men and women into musculoskeletal computer simulations. We evaluated the simulations to determine fundamental coordination principles of the squat jump, and the effect of increased loading and gender on muscle strategies employed during the squat jump. Our results revealed that the plantar flexors and vasti were primarily involved in increasing the mechanical energy of the body, while the proximal muscles were primarily involved in redistributing energy throughout the body. The erector spinae muscles extended the lumbar spine, and contributed energy to the torso, while gluteus maximus and hamstrings extended the hip joint, and contributed energy to the pelvis. The vasti extended the knee joint, and contributed energy to the pelvis and torso. Our results suggested that the rectus femoris plays a critical role in converting rotational energy into vertical kinetic energy. Greater barbell loads reduced the rate of lumbar extension, and resulted in increased normalized energy contributions from soleus and vasti to the torso. When comparing the squat jumps between men and women, our results suggested that soleus and vasti are more active in men than women during the body-weight squat jump. / text

abstract / Real Estate and Construction / Doctoral / Doctor of Philosophy

Atom transfer radical polymerization is a new and important living polymerization mechanism because it can produce many different polymers with controlled microstructures and novel properties. The commercialization of these new polymers will require detailed polymer reaction engineering investigations. Mathematical models are essential in this stage because they can summarize our knowledge on polymers made by ATRP and help us to find the optimum conditions for their synthesis. This thesis studies the polymerization kinetics of ATRP with mathematical models based on our own experimental work and experimental data published by other researchers. ATRP with both monofunctional and bifunctional initiators are considered. This is one of very few studies combining detailed mathematical models for polymerization kinetics and polymer microstructure and experimental results in the area of ATRP. Fundamental mathematical models were used to study the main features of ATRP. Population balances and the method of moments were used to predict polymer average properties, while Monte Carlo models were used to predict the complete microstructural distributions. This type of comparison between different modeling techniques is seldom done in the literature, even for other polymerization techniques, and can lead to a better understanding of polymerization mechanisms and mathematical modeling techniques. Since the discovery of ATRP, approximately ten years ago, little attention has been given to bifunctional initiators. This thesis tries to extend our knowledge on this important class of initiators. Comparison between monofunctional and bifunctional initiators, both through mathematical modeling and experimentally, showed that bifunctional initiators have some advantages over monofunctional initiators for ATRP. Polymers made with bifunctional initiators have narrow molecular weight distributions, higher molecular weight averages, and higher monomer conversion for the same polymerization time. In addition to homopolymerization studies, this thesis presents mathematical models for copolymerization with ATRP and for processes combining ATRP and coordination polymerization. These models describe the detailed microstructures of these copolymers and permit a better understanding of ATRP with its advantages and pitfalls. An interesting conclusion from these modeling studies in atom transfer radical copolymerization is that the Mayo-Lewis terminal model is applicable to ATRP and that the copolymer composition in ATRP is independent of the equilibrium constants (activation and deactivation). In order to develop and validate these mathematical models, we collected experimental data in our own laboratories and also used experimental data available in the literature. Our experimental work focused on the homopolymerization and copolymerization of styrene, because of the commercial importance of this monomer and also due to the relative simplicity of its polymerization. Experimental data collected from the literature covered the following systems: bulk homopolymerization of styrene, solution polymerization of styrene, solution polymerization of methyl methacrylate, bulk polymerization of n-butyl acrylate, bulk copolymerization of styrene and n-butyl acrylate. Different characterization techniques were used to determine polymer properties. Molecular weight and molecular weight distribution were measured using gel permeation chromatography (GPC); copolymer chemical composition was determined with nuclear magnetic resonance (NMR) and Fourier-transform infrared (FTIR). We have also done copolymerization with styrene and acrylonitrile (SAN) because it is one of the least understood ATRP system and also because its potential industrial importance. The ability to synthesize polymers with novel molecular architectures is one of the advantages of living polymerization techniques. In this thesis, we used ATRP to produce amphiphilic copolymers composed of polystyrene and polyethylene glycol methacrylate macromonomers. We have shown that ATRP can produce these very interesting polymers with two different types of macroinitiators.

d region, which is of relevance to Undersea Warfare.

Parmi leurs applications prometteuses, les lignées de cellules souches embryonnaires humaines (hES) présentent un potentiel inestimable pour améliorer la compréhension des mécanismes moléculaires et cellulaires impliqués dans le développement de maladies monogéniques. Cette application de modélisation pathologique est devenue possible grâce à l’utilisation de lignées hES porteuses de la mutation causale d’une maladie monogénique, obtenues au cours d’un diagnostique pré-implantatoire. L’équipe dans laquelle j’ai effectué mes travaux de thèse a démontré que des lignées hES et leurs progénies, porteuses de la mutation causale de la dystrophie myotonique de type 1 (DM1), exprimaient des défauts moléculaires caractéristiques de la pathologie, permettant ainsi leur analyse de façon plus pertinente par rapport à des cultures primaires dérivées de biopsies de patients et validant l’utilisation de ce modèle cellulaire. Dans ce contexte, dans la première partie de mon travail de thèse, mon objectif a été de mettre au point des conditions de culture permettant la différenciation des cellules hES normales et mutantes vers le lignage neural afin d’obtenir des populations homogènes de progéniteurs neuraux et de cellules souches neurales, puis de les caractériser sur le plan phénotypique et fonctionnel. Par une étude transcriptomique, j’ai ensuite comparé le profil d’expression de ces progéniteurs neuraux à une autre population homogène de précurseurs mésenchymateux. J’ai ainsi identifié des gènes et des voies de signalisation spécifiques à chacune de ces populations. (Article 1). Dans la seconde partie de mes travaux, ma contribution au projet de modélisation pathologique de DM1 a été d’utiliser ces progéniteurs neuraux et les cellules souches neurales mutés pour explorer les mécanismes physiopathologiques responsables des symptômes neurologiques observés dans cette pathologie. J’ai ainsi identifié une anomalie dans une voie de signalisation cellulaire perturbée, la voie la voie mTORC1, basée sur l’observation selon laquelle les cellules NSC porteuses de la mutation DM1 proliféraient plus lentement que les cellules contrôles (Article II). J’ai également étudié l’expression la protéine Tau, connue pour son implication dans la maladie d’Alzheimer, et mis en évidence des modifications suggérant une altération du transport axonal dans les neurones issus des lignées hES mutantes. Ces résultats, associés à ceux réalisés dans l’équipe, permettent d’apporter la preuve de concept de l’intérêt d’un tel modèle cellulaire pour la modélisation pathologique des maladies monogéniques. / Among their promising applications, human embryonic stem cells lines (hES) have huge potential to improve the understanding of molecular and cellular mechanisms involved in the development of monogenic diseases. This application of modeling pathologic became possible using hES cell lines carrying the causal mutation of a monogenic disease, obtained during pre-implantation diagnosis. The team where I did my thesis work demonstrated that hES cell lines and their progeny, carrying the causal mutation in myotonic dystrophy type 1 (DM1), expressing the molecular defects characteristic of the pathology, allowing more relevant analysis than primary cultures derived from biopsies of patients and validates the use of this cell model. In this context, in the first part of my thesis, my goal was to develop culture conditions for hES cell differentiation into normal and mutant neural lineage in order to obtain homogeneous populations of neural progenitors and neural stem cells and to characterize their phenotypic and fonctional preperties. Next, using a transcriptomic method, I compared the expression profile of neural progenitors to another homogeneous population of mesenchymal precursors. Thus, I identified genes and signaling pathways specific to each of these populations. (Article 1). In the second part of my work, my contribution to the pathological modeling of DM1 was to use these mutant neural progenitor cells and neural stem cells to explore the pathophysiological mechanisms involved in neurological symptoms observed in this pathology. Thus, I have identified a cell signaling pathway defects in mTORC1 pathway based on the observation that NSC cells carrying DM1 mutation proliferated more slowly than control cells (Article II).At last, I also studied the expression of Tau protein, a protein involved in Alzheimer’s disease and I have highlighted changes suggesting impairement of axonal transport in neurons derived from hES cell lines mutant. These results, together with those performed in the team, can provide proof of concept for the benefit of such a cell model for modeling disease monogenic diseases.

The current research seeks to develop a computational model that accurately describes particle dispersion in turbulent ow. Current particle dispersion models do not accurately predict the small-scale clumping of particles in turbulent ow that occurs due to interaction with turbulent eddies. A new stochastic vortex structure (SVS) model was developed and compared with current stochastic Lagrangian models (SLM) for turbulent ows. To examine what characteristics of the uid ow eld that lead to dispersion of particles, a number of non trivial measures were used. A discrete-element model is used to transport particle locations for cases with and without adhesive forces. Direct numerical simulations (DNS) are used as a baseline for comparison between the two models. Initial results show that the SVS model matches the spatial structure of the ow eld of DNS reasonably well, while the SLMs do not. Investigation of particle collision rate suggest that while SVS matches the large length scales of ow, it omits the smaller scales of the ow.

Recent studies have identified the Class B g-protein coupled receptor (GPCR) pituitary adenylate cyclase activating polypeptide type 1 (PAC1R) as a key component in physiological stress management. Over-activity of neurological stress response systems due to prolonged or extreme exposure to traumatic events has led researchers to investigate PAC1R inhibition as a possible treatment for anxiety disorders such as post-traumatic stress disorder (PTSD). In 2008, Beebe and coworkers identified two such small molecule hydrazide antagonists and a general pharmacaphore for PAC1R inhibition. However, a relative dearth of information about Class B GPCRs in general, and PAC1R in specific, has significantly hindered progress toward the development of small molecule antagonists of PAC1R. The recent crystallization of the homologically similar glucagon receptor (GCGR) by Siu and coworkers in 2013, also a Class B receptor, has provided an experimentally resolved template from which to base computationally derived models of PAC1R. Initially, this research was focused towards synthesizing small molecule antagonists for PAC1R which were to be biologically screened via a qualitative western blot assay followed by a radioisotope binding assay for those hydrazides exhibiting down-stream signaling inhibitory capabilities. However, the resolution of the GCGR crystal structure shifted research objectives towards developing a homology model of PAC1R and evaluating that computationally created model with Beebe's known small molecule antagonists. Created using academic versions of on-line resources including UniProtKB, Swiss-Model and Maestro, a homology model for PAC1R is presented here. The model is validated and evaluated for the presence of conserved Class B GPCR residues and motifs, including expected disulfide bridges, a conserved tyrosine residue, a GWGxP motif, a conserved glutamic acid residue and the extension of the transmembrane helix 1 (TM1) into the extra-cellular domain. Having determined this virtual PAC1R an acceptable model, ligand docking studies of known antagonists to the receptor were undertaken using AutoDock Vina in conjunction with AutoDock Tools and PyMol. Computational docking results were evaluated via comparison of theoretical binding affinity results to Beebe's experimental data. Based on hydrogen bonding capabilities, several residues possibly key to the ligand-receptor binding complex are identified and include ASN 240, TYR 241 and HIST 365. Although the docking software does not identify non-bonding interactions other than hydrogen-bonding, the roles of additional proposed binding pocket residues are discussed in terms of hydrophobic interactions, π-π interactions and halogen bonding. These residues include TYR 161, PHE 196, VAL 203, PHE 204, ILE 209, LEU 210, VAL 237, TRP 297, PHE 362 and LEU 386. Although theoretical in nature, this reported homology modeling and docking exercise details a proposed binding site that may potentially further the development of drugs designed for the treatment of PTSD.

In 2004, a field sampling study was initiated along the southern shoreline area of Lake Pontchartrain in Jefferson Parish, specifically, around Bonnabel Canal (Pumping Station No.1) to identify the effect of urban stormwater discharges on Lake Pontchartrain and to simulate the plume patterns from the Bonnabel Canal. Sixteen sampling stations were selected along the south shore of Lake Pontchartrain. Under dry weather conditions Fecal Coliform values exceeded the limit of 200 MPN/100mL at 3 of 16 stations. Fecal Coliform counts were found to be "wet" weather-dependent and unsuitable for primary contact recreation for at least three to four days following a pumping/rain event. A 3-D Hydrodynamic Model (COHERENS) and the TECPLOT™ equation feature were used for the prediction of contaminant plumes from the Bonnabel Canal into the Lake Pontchartrain. The model verified the three day wet weather effect of stormwater discharges along the shoreline of the study area.

When planning for a tunnel, the ground conditions in which the tunnel is going to be excavated through will be investigated to different extent. Lack of relevant pre-investigation data or misinterpretations of the available data can cause both economical and/or unexpected stability problems. Weakness zones that are expected to cross the tunnel could be investigated thoroughly with a variety of methods. Refraction seismicity survey and 2D resistivity survey are two geophysical methods that are common in Norway for obtaining information about the rock quality in weakness zones. In this work, a twin tunnel under construction in Bodø (northern Norway) called the Bodøtunnel is studied. The predictions based on the pre-investigation for crossing of some expected weakness zones are compared to the actual conditions encountered during tunneling. Tunneling observations (Geological mapping and photos), rock samples and measurement while drilling (MWD) were used to describe the weakness zones that were encountered during tunneling. Rock samples were collected from two weakness zones and the general rock mass. These samples were tested in a point bearing machine for determination of their uniaxial compressive strength (UCS). These results indicated that the rock samples gathered from the weakness zones had significantly lower UCS than the samples from the rock mass. This was exceedingly clear for the samples of fault rock gathered in connection with a shear zone. The results from this work demonstrate that refraction seismicity had a high success rate for locating weakness zones, with the exception for the crossed narrow zones that were interpreted lacking a shear component. Empirical formulas relating Q-value and UCS with the seismic wave speed were used for calculating these factors for some interesting locations. The empirically calculated UCS was similar to the obtained UCS from the point bearing tests, while the empirically calculated Q-value showed large deviations from the mapped Q-value. The resistivity measurements had a low success rate so far in this project; the reason for this could be disturbances in the ground and the location of the resistivity profiles, which had to adapted to the nearby railroad. It should be noted that only one full resistivity profile has been crossed and the rest of the profiles are expected to be more accurate. Based on the results from the crossed profile(s), the suitability of resistivity survey 2D in urban areas can be brought to question. This work also stumbled upon problems regarding the definition of weakness zones. Shear/fault zones are one of the more common type of weakness zones encountered in tunneling. These kind of zones often consists of different parts. Depending on which parts are regarded as a weakness zone by the responsible engineers, the Q-value might differ due to the SRF. Different scenarios were also evaluated with numerical modeling for the expected remaining major weakness zones. This analysis highlights the importance of differentiation between more fractured zones and zones containing fault rock, such as breccia. The width of the zone had a major impact on the stability while the dip for wide zones had a minor impact on the stability, as long the zones dip is not so small that both tunnels are intersected at the same time. The rock mechanical parameter of the weakness zones that had the most impact on the overall stability was the cohesion.

A study on the slag dispersion in bath smelting converter was undertaken. The aim was mainly to investigate the behaviour of the dispersed slag phase at high gas flow rate and low slag volume (10%) systems. For simulations purposes, water; paraffinoil and air were used in a one fifth model of the commercial 100 ton Creusot-Loire- Uddeholm converter to represent bulk steel, molten slag and gas respectively. Emulsion samples were collected by means of the specially made syringe. The experimental results revealed that the dispersed slag phase decreased with the vertical distance from the original interface between the liquid phases. The dispersed phase decreased also with the radial distance in the water plume zone towards the wall side. The holdup was apparently much observable on the right side than on the left side. Four dimensionless numbers defined the dispersion phenomenon through the dimensional analysis. The modified Froude Number ensured the correlation between both model and prototype. The standard error of the estimate and R-squared between the experimental and the calculated results were 3.7 ´10-4 and 0.97 respectively.