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<title>Open Access Dissertations</title>
<copyright>Copyright (c) 2013 University of Massachusetts - Amherst All rights reserved.</copyright>
<link>http://scholarworks.umass.edu/open_access_dissertations</link>
<description>Recent documents in Open Access Dissertations</description>
<language>en-us</language>
<lastBuildDate>Fri, 12 Apr 2013 01:40:46 PDT</lastBuildDate>
<ttl>3600</ttl>



	
		
	



	
		
	



	
		
	



	
		
	



	
		
	



	
		
	



	
		
	



	
		
	



	
		
	









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<title>Particle-Collector Interactions In Nanoscale Heterogeneous Systems</title>
<link>http://scholarworks.umass.edu/open_access_dissertations/724</link>
<guid isPermaLink="true">http://scholarworks.umass.edu/open_access_dissertations/724</guid>
<pubDate>Wed, 10 Apr 2013 06:56:05 PDT</pubDate>
<description>
	<![CDATA[
	<p>Particle-surface interactions govern a myriad of interface phenomena, that span from technological applications to naturally occurring biological processes.</p>
<p>In the present work, particle-collector DLVO interactions are computed with the grid-surface integration (GSI) technique, previously applied to the computation of particle colloidal interactions with anionic surfaces patterned with O(10 nm) cationic patches. The applicability of the GSI technique is extended to account for interactions with collectors covered with topographical and chemical nanoscale heterogeneity. Surface roughness is shown to have a significant role in the decrease of the energy barriers, in accordance with experimental deposition rates that are higher than those predicted by the DLVO theory for smooth surfaces. An energy- and force-averaging technique is presented as a reformulation of the GSI technique, to compute the mean particle interactions with random heterogeneous collectors. A statistical model based on the averaging technique is also developed, to predict the variance of the interactions and the particle adhesion thresholds. An excellent agreement is shown between the models' predictions and results obtained from GSI calculations for large number of random heterogeneous collectors.</p>
<p>Brownian motion effects for particle-collector systems governed by nanoscale heterogeneity are analyzed by introducing stochastic Brownian displacements in particle trajectory equations. It is shown that for the systems under consideration and particle sizes usually used in experiments, it is reasonable to neglect the effects of Brownian motion entirely. Computation of appropriately defined P ́eclet numbers that quantify the relative importance of shear, colloidal and Brownian forces validate that conclusion.</p>
<p>An algorithm for the discretization of spherical surfaces into small equal-area elements is implemented in conjunction with the GSI technique and mobility matrix calculations of particle velocities, to obtain interactions and dynamic behaviors of patchy particles in the vicinity of uniform flat collectors. The patchy particle and patchy collector systems are compared in detail, through the computation of statistical measures that include adhesion probabilities and maximum residence times per patch. The lessened tendency of the patchy particle to adhere on the uniform collector is attributed to a larger maximum residence time per patch, which precludes interactions with multiple surface nano-features at a given simulated time.</p>
<p>Also briefly described are directions for future work, that involve the modeling of two heterogeneous surfaces, and of surfaces covered with many types of heterogeneity, such as patches, pillars and spring-like structures that resemble polymer brushes or cellular receptors.</p>

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<author>Bendersky, Marina</author>

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<title>Measuring Proton Spin Polarizabilities with Polarized Compton Scattering</title>
<link>http://scholarworks.umass.edu/open_access_dissertations/723</link>
<guid isPermaLink="true">http://scholarworks.umass.edu/open_access_dissertations/723</guid>
<pubDate>Wed, 10 Apr 2013 06:56:04 PDT</pubDate>
<description>
	<![CDATA[
	<p>Polarized nuclear Compton scattering on a proton target provides a test of low energy QCD. The beam-target asymmetries of a circularly polarized Bremsstrahlung photon beam on a transversely polarized butanol target (&Sigma<sub>2x</sub>) and on a longitudinally polarized butanol target (&Sigma<sub>2z</sub>), and the beam asymmetry of a linearly polarized Bremsstrahlung beam on an unpolarized hydrogen target (&Sigma<sub>3</sub>) are sensitive to the proton spin polarizabilities, third order terms in the energy expansion of the Compton scattering amplitude. This experiment consisted of the &Sigma<sub>2x</sub> measurement, both just below and above two-pion threshold.</p>

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<author>Martel, Philippe Paul</author>

<source></source>

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<title>Helical Ordering in Chiral Block Copolymers</title>
<link>http://scholarworks.umass.edu/open_access_dissertations/722</link>
<guid isPermaLink="true">http://scholarworks.umass.edu/open_access_dissertations/722</guid>
<pubDate>Wed, 10 Apr 2013 06:56:03 PDT</pubDate>
<description>
	<![CDATA[
	<p>The phase behavior of chiral block copolymers (BCPs*), namely, BCPs with at least one of the constituent block is formed by chiral monomers, is studied both experimentally and theoretically. Specifically, the formation of a unique morphology with helical sense, the H* phase, where the chiral block forms nanohelices hexagonally embedded in the matrix of achiral block, is investigated. Such unique morphology was first observed in the cast film of polystyrene-<em>b</em>-poly(L-lactide) (PS-<em>b</em>-PLLA) from a neutral solvent dichloromethane at room temperature with all the nanohelices being left-handed, which would switch to right-handed if the PLLA block changes to PDLA. Further studies revealed that such morphology only forms when the chiral PLLA block possesses certain volume fraction (from 0.32 to 0.36), and the molecular weight exceeds certain critical value (around 20,000 to 25,000 g/mol). Achiral phases such as lamellae, gyroid, cylinder, and sphere will form if the above criteria are not satisfied. Even though the unique H* phase has been extensively studied and utilized for many applications, many fundamental and important questions remain unanswered for such BCP* system. Specifically, how does the molecular level chirality transfer from the several-angstrom scale of the lactide monomer to the tens-of-nanometer size scale of the H* domain morphology? Why is the chirality transfer not automatic for this BCP* system? Is H* phase a thermodynamic stable or metastable phase? Are there other novel phases other than the H* phase that could form within the BCP* system?</p>
<p>We aimed at providing answers to the abovementioned questions regarding the formation of chiral H* phase, which is no longer limited to the PS-<em>b</em>-PLLA/PDLA system. We divided our studies into both experimental and theoretical parts. In the experiments, we studied the effect of solvent casting conditions, including solvent removal rate and polymer-solvent interactions, on the formation of the H* phase in PS-<em>b</em>-PLLA/PDLA BCPs*. In addition, we monitored the morphological evolution during solvent casting using time-resolved x-ray scattering technique. We found that good solubility towards both PS and PLLA/PDLA blocks are required for the formation of the H* phase, and microphase separation has to happen prior to crystallization of chiral block. Most importantly, we found that crystalline ordering is not necessary for the H* phase formation. This result led us to propose melt-state twisted molecular packing as the underlying driving force for such helical phase to form, and began our work on the theory for BCPs*. First we built the theoretical tool by incorporating the orientational segmental interactions into the self-consistent field theory (SCFT) for BCPs. As a demonstration, we constructed the phase diagrams for one-dimensional (1D) and two-dimensional (2D) phases, for achiral BCPs with different orientational stiffness. We found that orientational stiffness could serve as another parameter to introduce asymmetry into BCP systems, in addition to conformational and architectural asymmetry. This model was further applied to study the phase behavior of BCPs*, and two phase diagrams were constructed. Another chiral phase, wavy lamellae (L* phase), was observed for BCPs*. The H* phase was found to be a thermodynamic stable phase, as long as the segregation strength 𝜒𝑁and chiral strength 𝑞! exceed certain critical values. Energetically favorable cholesteric texture was observed for the chiral segment packing inside the H* phase, which is believed to drive such unusual morphology to form. A simple geometrical argument based on bending of cylindrical microdomain and twisted packing of the bended microdomain can be given to explain the nonlinear chiral sensitivity of BCP* morphology, which further explains the non-automatic feature of chirality transfer in such system.</p>

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<author>Zhao, Wei</author>

<source></source>

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<title>Development and Characterization of Caspase Activatable GFP and a Family of Fluorescent Reporters</title>
<link>http://scholarworks.umass.edu/open_access_dissertations/721</link>
<guid isPermaLink="true">http://scholarworks.umass.edu/open_access_dissertations/721</guid>
<pubDate>Tue, 09 Apr 2013 08:21:48 PDT</pubDate>
<description>
	<![CDATA[
	<p>The cellular process of programmed cell death, or apoptosis, is critical in homeostasis and development. In addition it's misfunction is implicated in an array of disease states from cancer to neurodegeration, making it an attractive pathway for drug targeting. A family of proteases, known as caspases, plays a central role in the apoptotic cascade resulting in the ultimate destruction of the cell. We report a genetically encoded dark-to-bright reporter of caspase activity used in E.coli, mammalian cells, and whole organisms which can be used to monitor apoptosis. This reporter, caspase activatable green fluorescent protein (CA-GFP) consists of GFP fused through a flexible linker containing the caspase-3 and -7 recognition sequence, DEVD, to a hydrophobic peptide derived from the influenza A viral M2 protein. This fusion reporter shows a significant fluorescent response in the presence of active caspase. CA-GFP is unique in its ability to hold GFP in a dark state prior to cleavage by active protease. We investigate the mechanism of quenching, examining the structural characteristics which lead to the inability of the GFP chromophore to mature in the presence of the peptide. In better understanding the mechanism of quenching we can engineer CA-GFP to ultimately be used in transgenic animal models. This requires the development of a palette of protease-activatable fluorescent proteins (PrA-FP) which would enable the monitoring of multiple proteolytic events within a cell or organism in real time. Our development of this palette of reporters, varying in their fluorescence and proteolytic response shows that CA-GFP has the potential to be a powerful tool for the study of the role of apoptosis during development in whole organism models and could be an important tool in understanding the role of individual proteases within the complex biochemical environment in the cell.<strong></strong></p>

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<author>Nicholls, Samantha Elizabeth Bernard</author>

<source></source>

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<title>Multiscale Modeling of Human Addiction: a Computational Hypothesis for Allostasis and Healing</title>
<link>http://scholarworks.umass.edu/open_access_dissertations/720</link>
<guid isPermaLink="true">http://scholarworks.umass.edu/open_access_dissertations/720</guid>
<pubDate>Tue, 09 Apr 2013 08:13:53 PDT</pubDate>
<description>
	<![CDATA[
	<p>This dissertation presents a computational multiscale framework for predicting behavioral tendencies related to human addiction. The research encompasses three main contributions. The first contribution presents a formal, heuristic, and exploratory framework to conduct interdisciplinary investigations about the neuropsychological, cognitive, behavioral, and recovery constituents of addiction. The second contribution proposes a computational framework to account for real-life recoveries that are not dependent on pharmaceutical, clinical, and counseling support. This exploration relies upon a combination of current biological beliefs together with unorthodox rehabilitation practices, such as meditation, and proposes a conjecture regarding possible cognitive mechanisms involved in the recovery process. Further elaboration of this investigation leads on to the third contribution, which introduces a computational hypothesis for exploring the allostatic theory of addiction. A person engaging in drug consumption is likely to encounter mood deterioration and eventually to suffer the loss of a reasonable functional state (e.g., experience depression). The allostatic theory describes how the consumption of abusive substances modifies the brain's reward system by means of two mechanisms which aim to viably maintain the functional state of an addict. The first mechanism is initiated in the reward system itself, whereas the second might originate in the endocrine system or elsewhere. The proposed computational hypothesis indicates that the first mechanism can explain the functional stabilization of the addict, whereas the second mechanism is a candidate for a source of possible recovery.</p>
<p>The formal arguments presented in this dissertation are illustrated by simulations which delineate archetypal patterns of human behavior toward drug consumption: escalation of use and influence of conventional and alternative rehabilitation treatments. Results obtained from this computational framework encourage an integrative approach to drug rehabilitation therapies which combine conventional therapies with alternative practices to achieve higher rates of consumption cessation and lower rates of relapse.</p>

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<author>Levy, Yariv Z.</author>

<source></source>

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<title>Determining Detailed Reaction Kinetics for Nitrogen-and Oxygen-Containing Fuels</title>
<link>http://scholarworks.umass.edu/open_access_dissertations/719</link>
<guid isPermaLink="true">http://scholarworks.umass.edu/open_access_dissertations/719</guid>
<pubDate>Tue, 09 Apr 2013 08:05:13 PDT</pubDate>
<description>
	<![CDATA[
	<p>With the emergence of new biorenewable transportation fuels, the role of heteroatoms in combustion has increased tremendously. While petroleum-based fuels are primarily hydrocarbons, many biorenewable fuels contain heteroatoms such as oxygen and nitrogen, introducing new challenges associated with toxic emissions. A fundamental understanding of the chemical kinetics of combustion of these heteroatomic fuels is necessary to elucidate the pathways by which these toxic emissions are formed and may be achieved through the development of combustion models. Reaction sets, the core of these combustion models, may be assembled for individual fuels through a balance of employing vetted rate constants from prior publications, quantum chemistry calculations, and rate constant estimations. For accuracy, reaction sets should be tested against experimental combustion studies such as low-pressure flame experiments using molecular-beam mass spectrometry (MBMS) or chemiluminescence and high-pressure shock-tube experiments.</p>
<p>This dissertation presents the development of a new reaction set to describe gas-phase combustion chemistry of fuels containing only hydrogen, carbon, oxygen, and nitrogen. The foundation of this model was a reaction set to describe combustion of ammonia flames. This reaction set contains only H/N/O chemistry for simplicity. The new reaction set was tested against a pyrolysis shock-tube study, as well as 12 MBMS flame experiments under a variety of conditions, including different mixtures of fuels and oxidizers (NH<sub>3</sub>, N<sub>2</sub>O, H<sub>2</sub>, NO, O<sub>2</sub>), fuel equivalence ratios (lean to rich), pressures, and concentrations of diluent gas. Additionally, the base H/N/O mechanism was expanded to include carbon chemistry and was tested against flames of dimethylamine, ethylamine, and a methane/ammonia mixture.</p>
<p>This reaction set was employed to study heterocyclic biofuels including a fuel-rich flame of tetrahydropyran, the monoether analogue to cyclohexane and the basic ring in cellulose. Additionally, the model was used in a study of morpholine, a 6-membered ring with both ether and amine functionalities, testing the model against fuel-rich flame studies using both MBMS and chemiluminescence techniques and high-pressure shock-tube studies for both oxidation and pyrolysis at elevated temperatures and pressures. Lastly, the model was used to study the combustion of hypergolic rocket fuels, specifically monomethyl hydrazine and tetramethylethyldiamine with red fuming nitric acid.</p>

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<author>Labbe, Nicole Jeanne</author>

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<title>Intellectual Constellations in the Postsocialist Era: Four Essays</title>
<link>http://scholarworks.umass.edu/open_access_dissertations/718</link>
<guid isPermaLink="true">http://scholarworks.umass.edu/open_access_dissertations/718</guid>
<pubDate>Tue, 09 Apr 2013 07:55:13 PDT</pubDate>
<description>
	<![CDATA[
	<p>In an attempt to facilitate the task of charting a path toward a radically different future, a future without the bourgeois intellectual property regime (IPR), this dissertation searches back in history by examining China's loss of socialism.</p>
<p>The guiding question can be formulated thus: Why did the People's Republic of China give up its socialist mode of intellectual production only to embrace the bourgeois intellectual property regime (IPR), which had been subjected to devastating criticism by progressive scholars in the West since mid-1990s? Situating this rupture of China's approach to intellectual production within the ongoing process of postsocialist structuration in the wake of the waning Chinese socialism, this dissertation focuses on Chinese intellectuals as social mediators and locates the traces of the loss of socialism in various cultural productions during the postsocialist era.</p>

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</description>

<author>Gu, Li</author>

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<title>Accurate and Robust Mechanical Modeling of Proteins</title>
<link>http://scholarworks.umass.edu/open_access_dissertations/717</link>
<guid isPermaLink="true">http://scholarworks.umass.edu/open_access_dissertations/717</guid>
<pubDate>Tue, 09 Apr 2013 07:50:39 PDT</pubDate>
<description>
	<![CDATA[
	<p>Through their motion, proteins perform essential functions in the living cell. Although we cannot observe protein motion directly, over 68,000 crystal structures are freely available from the Protein Data Bank. Computational protein rigidity analysis systems leverage this data, building a mechanical model from atoms and pairwise interactions determined from a static 3D structure. The rigid and flexible components of the model are then calculated with a pebble game algorithm, predicting a protein's flexibility with much more computational efficiency than physical simulation. In prior work with rigidity analysis systems, the available modeling options were hard-coded, and evaluation was limited to case studies.</p>
<p>The focus of this thesis is improving accuracy and robustness of rigidity analysis systems. The first contribution is in new approaches to mechanical modeling of noncovalent interactions, namely hydrogen bonds and hydrophobic interactions. Unlike covalent bonds, the behavior of these interactions varies with their energies. I systematically investigate energy-refined modeling of these interactions. Included in this is a method to assign a score to a predicted cluster decomposition, adapted from the B-cubed score from information retrieval. Another contribution of this thesis is in new approaches to measuring the robustness of rigidity analysis results. The protein's fold is held in place by weak, noncovalent interactions, known to break and form during natural fluctuations. Rigidity analysis has been conventionally performed on only a single snapshot, rather than on an entire trajectory, and no information was made available on the sensitivity of the clusters to variations in the interaction network. I propose an approach to measure the robustness of rigidity results, by studying how detrimental the loss of a single interaction may be to a cluster's rigidity. The accompanying study shows that, when present, highly critical interactions are concentrated around the active site, indicating that nature has designed a very versatile system for transitioning between unique conformations.</p>
<p>Over the course of this thesis, we develop the KINARI library for experimenting with extensions to rigidity analysis. The modular design of the software allows for easy extensions and tool development. A specific feature is the inclusion of several modeling options, allowing more freedom in exploring biological hypotheses and future benchmarking experiments.</p>

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<author>Fox, Naomi</author>

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<title>Analysis of the Spatiotemporal Localization of Mitochondrial DNA Polymerases of &lt;i&gt;Trypanosoma brucei&lt;/i&gt;</title>
<link>http://scholarworks.umass.edu/open_access_dissertations/716</link>
<guid isPermaLink="true">http://scholarworks.umass.edu/open_access_dissertations/716</guid>
<pubDate>Tue, 09 Apr 2013 07:36:08 PDT</pubDate>
<description>
	<![CDATA[
	<p><strong>The mitochondrion contains its own genome. Replication of the mitochondrial DNA (mtDNA) is an essential process that, in most organisms, occurs through the cell cycle with no known mechanism to ensure spatial or temporal constrain. Failures to maintain mtDNA copy number affects cellular functions causing several human disorders. However, it is not clear how the cells control the mtDNA copy number. The mtDNA of trypanosomes, known as kinetoplast DNA (kDNA), is a structurally complex network of topologically interlocked DNA molecules (minicircles and maxicircles). The replication mechanism of the kDNA differs greatly with all other eukaryotic systems. Key features of the kDNA replication mechanism include defined regions for main replication events, coordination of a large number of proteins to drive the replication process, and replication once per cell cycle in near synchrony with nuclear S phase. Two main regions known as the kinetoflagellar zone (KFZ) and the antipodal sites are where main kDNA replication events are known to occur (i.e, initiation, DNA synthesis and Okazaki fragment processing). So far, the localization of the proteins involved in kDNA replication is restricted to two main regions: the KFZ and the antipodal sites. Three mechanisms that directly regulate kDNA replication proteins and serve to control kDNA replication have been proposed: (1) Reduction and oxidation status of the universal minicircle sequence binding protein (UMSBP) controls its binding to the origin sequence, (2) Trans-acting factors regulate the stability of mRNA encoding mitochondrial Topoisomerase II during the cell cycle and, (3) Regulation of TbPIF2 helicase protein levels by a HslVU-like protease to control maxicircle copy number. These mechanisms seem to be protein specific and it appears that a combination rather than a single mechanism regulates kDNA replication.</strong></p>
<p><strong> In this study we used <em>Trypanosoma brucei</em> to understand how mitochondrial DNA replication is controlled. We investigated the mechanism of how proteins transiently localize to the sites of DNA synthesis during cell cycle stages. Our data provides a comprehensive analysis of the first two examples of <em>T. brucei</em> kDNA replication proteins that have a cell cycle dependent localization (Ch. 2 and 3). The localization of two of the three essential mitochondrial DNA polymerases (TbPOLIC and TbPOLID) is under tight cell cycle control and not regulated by proteolysis. TbPOLIC and TbPOLID localize to the antipodal sites during kDNA S phase, however, at other cell cycle stages TbPOLIC becomes undetectable by immunofluorescent analysis and TbPOLID disperses through the mitochondrial matrix. In agreement with this data, TbPOLIC and TbPOLID replication complexes were not detected using affinity purification presumably because only a fraction of these proteins are participating in replication at a given time (Ch. 4). We propose that spatial and temporal changes in the dynamic localization of essential kDNA replication proteins provide a novel mechanism to control kDNA replication.</strong></p>

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<author>Concepcón-Acevedo, Jeniffer</author>

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<title>Adsorption column studies to predict the flow of nutrients through heterogenous porous media under equilibrium and isothermal conditions</title>
<link>http://scholarworks.umass.edu/open_access_dissertations/715</link>
<guid isPermaLink="true">http://scholarworks.umass.edu/open_access_dissertations/715</guid>
<pubDate>Tue, 26 Mar 2013 13:10:35 PDT</pubDate>
<description>
	<![CDATA[
	<p>Because of the endangerment of life of the human beings due to the environmental pollution, a serious study of the pollution of the environment is most vital. Because of increasing surface water pollution there is great hazard of ground water pollution. About half the United States of America derives drinking water from aquifers and much of the projected demand is expected to be met from subsurface sources. Therefore, a study was needed to determine the process of ground water contamination due to nutrients, especially Nitrogen, its degree and Length and Time of Travel and factors inhibiting its flow through soil.</p>
<p>The present study was undertaken at the 'Pine Crest Duck Farm' at Sterling, Massachusetts, where the nature of the soil was Gravely Sandy Loam and Three unlined (from the side and bottom) waste stabilization ponds existed and there was a great danger of ground water contamination due to Nitrogen in the vicinity of ponds and further. In the field, observation wells were installed along the redial line and bi-monthly samples of water were taken to monitor the levels of B.O.D., Ammonium, Nitrate and Nitrite Nitrogen.</p>
<p>Since the Adsorption of the Nitrogen by the soil is great inhibitor in the movement of the Nitrogen through soil profiles, this study was undertaken to study the adsorptive capacity of the soil in 'Bench Tests' and to test the applicability and validity of various adsorption isotherms of nitrogen in the soil; to develop a dimensional model or prediction equation for the nitrogen in the soil under natural flow conditions by studying the effects of varying concentration and flow rates on the adsorptive capacity of the soil, based on the principles of similitude; to correlate adsorption values in bench and column tests; and to determine the length and time of travel of nitrogen through soil.</p>
<p>The soil from the Farm was obtained from a depth of six feet with enough care so that original structure was maintained. Adsorptive capacity of the soil was determined through series of 'Bench Tests' and 'Soil Adsorption Columns' in the laboratory under temperature controlled chambers. From the Bench Tests Adsorption values of the soil at various concentrations of Ammonium, Nitrate and Nitrite Nitrogen were determined and validity and applicability of Adsorption isotherms were confirmed.</p>
<p>To study the Adsorption Process under natural flow conditions 'Soil Adsorption Column Tests' were done by using never done before Dimensional Model Analysis of Factors affecting Adsorption and getting dimensionless numbers and further obtaining 'Break Through Curves' at different Concentration and flow rates and Adsorption Values were obtained for Ammonium Nitrogen and Nitrite Nitrogen. Finally, Component and Prediction Equations were obtained for Ammonium Nitrogen and Nitrate Nitrogen.</p>
<p>By knowing the Adsorption Values of the soil Length and Time of Travel of Ammonium and Nitrate Nitrogen through soil was calculated at various Concentration Levels. A mathematical Prediction Equation was also obtained between Bench and Column Tests and Length of Time of Travel, t predict the adsorption values under natural flow conditions by just performing less time consuming Bench Tests.</p>
<p>It was also found that under eqUilibrium Bench Test conditions and natural flow conditions, adsorption of Ammonium, Nitrate and Nitrite Nitrogen increased with increasing solution concentration and adsorption of Ammonium Nitrogen was considerably higher than Nitrate and Nitrite Nitrogen. It was further found that for solution concentrations of 20, 40, 60, 80 and 100 mgll Ammonium Nitrogen and nitrate nitrogen will travel one foot distance in 183 and 115 days; 168 and 111 days; 148 and 98 days; 145 and 81 days; 130 and 98 days; and 127 and 97 days respectively. It was determined that at the present time contamination of shallow water wells does not pose Nitrogen contamination problem and installation of these wells beyond 300 feet radial distance from the waste stabilization ponds was safe.</p>

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<author>Pandey, Vijai B.</author>

<source></source>

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<title>Assembly Of Surface Engineered Nanoparticles For Functional Materials</title>
<link>http://scholarworks.umass.edu/open_access_dissertations/714</link>
<guid isPermaLink="true">http://scholarworks.umass.edu/open_access_dissertations/714</guid>
<pubDate>Thu, 21 Mar 2013 10:35:58 PDT</pubDate>
<description>
	<![CDATA[
	<p>Nanoparticles are regarded as exciting new building blocks for functional materials due to their fascinating physical properties because of the nano-confinement. Organizing nanoparticles into ordered hierarchical structures are highly desired for constructing novel optical and electrical artificial materials that are different from their isolated state or thermodynamics random ensembles. My research integrates the surface chemistry of nanoparticles, interfacial assembly and lithography techniques to construct nanoparticle based functional structures. We designed and synthesized tailor-made ligands for gold, semiconductor and magnetic nanoparticle, to modulate the assembly process and collective properties of the assembled structures, by controlling the key parameters such as particle-interface interaction, dielectric environments and inter-particle coupling etc. Top-down technologies such as micro contact printing, photolithography and nanoimprint lithography are used to guide the assembly into arbitrarily predesigned structures for potential device applications.<strong></strong></p>

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<author>Yu, Xi</author>

<source></source>

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<title>Bayesian Anatomy of Galaxy Structure</title>
<link>http://scholarworks.umass.edu/open_access_dissertations/713</link>
<guid isPermaLink="true">http://scholarworks.umass.edu/open_access_dissertations/713</guid>
<pubDate>Thu, 21 Mar 2013 08:58:48 PDT</pubDate>
<description>
	<![CDATA[
	<p>In this thesis I develop Bayesian approach to model galaxy surface brightness and apply it to a bulge-disc decomposition analysis of galaxies in near-infrared band, from Two Micron All Sky Survey (2MASS). The thesis has three main parts.</p>
<p>First part is a technical development of Bayesian galaxy image decomposition package Galphat based on Markov chain Monte Carlo algorithm. I implement a fast and accurate galaxy model image generation algorithm to reduce computation time and make Bayesian approach feasible for real science analysis using large ensemble of galaxies. I perform a benchmark test of Galphat and demonstrate significant improvement in parameter estimation with a correct statistical confidence.</p>
<p>Second part is a performance test for full Bayesian application to galaxy bulgedisc decomposition analysis including not only the parameter estimation but also the model comparison to classify different galaxy population. The test demonstrates that Galphat has enough statistical power to make a reliable model inference using galaxy photometric survey data. Bayesian prior update is also tested for parameter estimation and Bayes factor model comparison and it shows that informative prior significantly improves the model inference in every aspects.</p>
<p>Last part is a Bayesian bulge-disc decomposition analysis using 2MASS Ks-band selected samples. I characterise the luminosity distributions in spheroids, bulges and discs separately in the local Universe and study the galaxy morphology correlation, by full utilising the ensemble parameter posterior of the entire galaxy samples. It shows that to avoid a biased inference, the parameter covariance and model degeneracy has to be carefully characterised by the full probability distribution.</p>

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<author>Yoon, Ilsang</author>

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<title>Racialized Spaces In Teacher Discourse: A Critical Discourse Analysis Of Place-Based Identities In Roche Bois, Mauritius</title>
<link>http://scholarworks.umass.edu/open_access_dissertations/712</link>
<guid isPermaLink="true">http://scholarworks.umass.edu/open_access_dissertations/712</guid>
<pubDate>Thu, 21 Mar 2013 08:38:55 PDT</pubDate>
<description>
	<![CDATA[
	<p>This eleven-month ethnographic study puts critical discourse analysis in dialogue with postmodern conceptualizations of space and place to explore how eight educators talk about space and in the process, produce racialized spaces in Roche Bois, Mauritius. The macro-historical context of racialization of this urban marginalized community informs the discursive analysis of educators' talk at school. Drawing on theories of race that call for the non-deterministic exploration of race relations as they occur in different contexts and times (Hall, 2000; Pandian & Kosek, 2003; Essed & Goldberg, 2000), I explore the spatial racialization of children in Roche Bois as a process specific to this township and its history. Engaging with Lefebvre's three-dimensional theorization of space (Lefebre, 1991) as well as the Discourse Historical Approach developed by Wodak and colleagues (Wodak & Reisgl, 1999), I draw on the micro-macro concept of identity construction "strategy" to study 1) how meanings of race play out as an amalgam of various thematic dimensions of schooling, culture, bodies, and work that are spatialized; 2) how meanings of place perpetuate or transform long-standing historical constructions of Creole identity in Roche Bois. The findings show that repeated patterns of educators' spatial racialization produce and reproduce conceived spaces (Lefebvre, 1991) and yet my research also highlights that banal moments of lived space (Lefebvre, 1991) also exist, as ordinary disruptions of the spatial order produced by patterns of conceived space. While educator discourse for the most part negatively emplaces and racializes the children, one educator's representations of place and race both assimilates and differentiates marginal identities, encourages unity and essentialism at the same time as promotes hybridity. The analysis therefore shows that discourses of place are not totalizing and that moments of interruption can be the basis for thinking of teacher education and practice as a politics of "decolonization" and "reinhabitation" (Gruenewald, 2003). Specifically, the findings indicate the importance of reinvesting critical historical meanings into pedagogies of the local.</p>

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<author>Wiehe, Elsa Marie</author>

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<title>Fan Communities and Subgroups: Exploring Individuals&apos; Supporter Group Experiences</title>
<link>http://scholarworks.umass.edu/open_access_dissertations/711</link>
<guid isPermaLink="true">http://scholarworks.umass.edu/open_access_dissertations/711</guid>
<pubDate>Thu, 21 Mar 2013 08:23:24 PDT</pubDate>
<description>
	<![CDATA[
	<p>The aggregate of a sport team’s fans may be viewed as a consumption community that surrounds the team and its brand (Devasagayam & Buff, 2008; Hickman & Ward, 2007). Beneath this larger consumption umbrella, smaller groups of consumers may exist (Dholakia, Bagozzi, & Pearo, 2004), such as specific supporter groups for a team. Individuals thus may identify with multiple layers of the consumption group simultaneously (Brodsky & Marx, 2001; Hornsey & Hogg, 2000). Although past researchers have studied supporter groups (Giulianotti, 1996, 1999a; Parry & Malcolm, 2004) and consumption communities (Kozinets, 2001; Muñiz & O’Guinn, 2001; McAlexander, Schouten, & Koenig, 2002), there has been limited research on the interaction among subgroups within the superordinate group.</p>
<p>The current study examines the American Outlaws (AO), a supporter group for the United States men’s national soccer team (USMNT). AO members belong to local AO chapters (subgroups) as well the national (superordinate) group. This structure creates multiple levels of identification and is conducive to studying the phenomenon in question. Through employing a grounded theory methodology, data were collected via participant observation and ethnographic interviews over a two year period.</p>
<p>The current study identifies six prominent foci of identification among AO members: the USMNT, the United States of America (national identity), the sport of soccer, AO National, AO Local, and one’s small social group. These identities are found to be mutually reinforcing and shape members’ interactions with the team, the supporter group, and social groups therein. Specifically, the regional subgroups (AO Local chapters) create opportunities for social interaction, which fosters members’ sense of community and group identification. In turn, this strengthens group cohesion at the subgroup and superordinate group levels. Further, supporter group members alter their team consumption experiences by creating places of prolonged identity salience at live games and when watching games on television. These events increase identification with the supporter group and its related identities. For practitioners, implications of this study include the understanding of supporter groups’ impact on members’ frequency and duration of brand-related consumption.</p>

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</description>

<author>Tyler, Bruce David</author>

<source></source>

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<item>
<title>Interactions between a Gall Making Fly, Dasineura Oxycoccana (Diptera: Cecidomyiidae), And Its Host Plant, Cultivated Cranberry (Vaccinium Macrocarpon)</title>
<link>http://scholarworks.umass.edu/open_access_dissertations/710</link>
<guid isPermaLink="true">http://scholarworks.umass.edu/open_access_dissertations/710</guid>
<pubDate>Thu, 21 Mar 2013 08:19:24 PDT</pubDate>
<description>
	<![CDATA[
	<p>Cranberry tipworm, <em>Dasineura oxycoccana </em>Johnson (a gall‐making fly), disrupts normal growth of cranberry (<em>Vaccinium macrocarpon </em>Aiton) by injuring the apical meristem of shoots or uprights. The impact of larval feeding injury on reproductive parameters of cranberry was determined, from one growing season to next, at upright (Maine and Massachusetts, 2008 ‐ 2009) and plot levels (Massachusetts, 2009 – 2010 and 2010 ‐ 2011). I also estimated the proportions of uprights injured because of tipworm feeding at several cranberry production sites (Massachusetts and Maine) and the proportions of uprights that produced flowers and fruits in the next growing season. Tipworm‐injured uprights tagged at the end of the growing season did not produce floral‐units (following year) across sites in both Massachusetts and Maine. There was significant variation among the sampled sites in the proportions of tipworm‐injured uprights and also in the proportions of uprights with flowers in the next growing season (Massachusetts and Maine). A trend was apparent wherein sites with higher tipworm injury levels had relatively lower flowering proportions in the next growing season. However, sites in Massachusetts did not differ in the proportions of uprights that set fruit and in a replicated study, significant reduction in tipworm injury at plot level (using insecticide) did not impact flower and fruit production in the next growing season. A two‐year field study was carried out at three different locations to determine the impact of tipworm feeding injury on the reproductive and vegetative growth of two cranberry cultivars (‘Howes’ and ‘Stevens’) in Massachusetts. Individual uprights of cranberry exhibited tolerance to natural (tipworm) and simulated apical meristem injury in the current growing season (fruit production) and results were corroborated by a greenhouse study. In the field study, weight of fruit was higher intipworm‐injured uprights as compared with intact control uprights at the sites with Howes. However, majority of injured uprights (tipworm and simulated) did not produce new growth from lateral buds (side‐shoots) before the onset of dormancy. In the next growing season, fewer injured uprights resumed growth and produced flowers as compared with intact uprights at two of the three sites.</p>

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</description>

<author>Tewari, Sunil</author>

<source></source>

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<item>
<title>Remember Where We Came From: Globalization And Environmental Discourse In The Araucania Region Of Chile</title>
<link>http://scholarworks.umass.edu/open_access_dissertations/709</link>
<guid isPermaLink="true">http://scholarworks.umass.edu/open_access_dissertations/709</guid>
<pubDate>Thu, 21 Mar 2013 08:13:17 PDT</pubDate>
<description>
	<![CDATA[
	<p>Based on an ethnographic investigation, the dissertation examines the emergence and significance of discourses around “the environment” in the Lake District of the Araucanía region of Chile (<em>Araucanía Lacustre</em>). These are understood as part of the discursive aspect of globalization – the process by which the territory and its population are integrated ever more tightly into the networks of global market society – and considered in conjunction with discourses around Mapuche indigenous identity. Drawing on mediacultural studies, actor network theory, and medium theory, the analysis seeks to advance an ecological concept of communication that does not privilege human consciousness and agency. Communication is argued to be the principle by which space (physical and metaphysical) is configured and connected. Through a discussion of the physical and human geography of the territory it is argued that discourse is mutually immanent with material realities, including human practice and pre-discursive, nonhuman elements (chapter 3). The connection between environmental discourse and Mapuche culture is examined through the stereotype of the ecologically virtuous indigenous subject – a stereotype whose significance is changing as parallel neoliberal multicultural and sustainable development discourses boost the prestige of both Mapuche culture and ecological responsibility, even as the steady expansion of market society undermines both (Chapter 2). A program run by an NGO, funded by the Chilean state, and intended to market the agro-ecological produce of Mapuche small farmers to tourists, provides a concrete case of the intersection of neoliberal multiculturalism with environmental discourse (Chapter 4). The concept of “postmaterialism” is adapted, with a critical edge, in an exploration of the environmental activism and a certain dissatisfaction with modernity among college educated immigrants to the District from Santiago, North America and Europe (chapter 5). The process of globalization, through which Mapuche <em>campesinos </em>come to use environmentalist discourses, involves interactions among old and new information technologies, transportation technologies, and the nonanthropogenic realities of physical space-time and geography (chapter 6). The dissertation concludes with a normative argument about the ethical and epistemological inadequacy of globalizing market society.</p>

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</description>

<author>Stephens, Niall</author>

<source></source>

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<item>
<title>Interactions between floral mutualists and antagonists, and consequences for plant reproduction</title>
<link>http://scholarworks.umass.edu/open_access_dissertations/708</link>
<guid isPermaLink="true">http://scholarworks.umass.edu/open_access_dissertations/708</guid>
<pubDate>Thu, 21 Mar 2013 08:07:39 PDT</pubDate>
<description>
	<![CDATA[
	<p>While pollinators and leaf herbivores have been a focus of research for decades, floral antagonists have been studied significantly less. Since floral antagonists can be as common as leaf herbivores and have strong impacts on plant reproduction, it is important to understand the role of floral antagonists in the ecology and evolution of flowers. I conducted four experiments to better understand the relationship between plants, floral traits, floral antagonists, and other plant-insect interactions. First, I manipulated resources (light and soil nutrients) that are known to have impacts on plants and floral traits to test how they affect floral antagonists and other plant-insect interactions. Plentiful resources increased the proportion of floral antagonists to visit flowers, but also increase tolerance of floral antagonists. Second, I manipulated flower bud gallers, a species-specific floral herbivore that destroys flowers, to test how it affected other plant-insect interactions, floral traits, and plant reproduction. Plants with flower bud gallers tended to have more pollinator visits, but this effect is due to a shared preference by gallers and pollinators for similar plants. Third, I manipulated florivory to examine how it affects subsequent plant-arthropod interactions, floral traits, and plant reproduction. Florivory had systemic effects on other plant-insect interactions, including leaf herbivores, and shifted the plant mating system towards more selfing. Additionally, I tested how several floral antagonists respond to floral attractive and defense traits to understand which floral traits are important in mediating antagonisms. Finally, I manipulated florivory, pollination, and nectar robbing to test for effects of multiple floral interactions on subsequent plant-insect interactions, floral traits, and plant reproduction. There were significant many-way interactions between the three treatments on subsequent plant-insect interactions and reproduction, indicating that the effect of one interaction depends on what other interactions are present. Understanding the role that floral antagonists play in plant ecology can help scientists determine which interactions are most important, and may help determine why some floral traits exist in their current state. Together, this work represents some of the most comprehensive research on the community consequences of floral antagonists, as well as the interplay between floral traits and floral interactions.<strong></strong></p>

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</description>

<author>Soper Gorden, Nicole Leland</author>

<source></source>

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<item>
<title>The Role of Capabilities in Innovation Adoption Decisions</title>
<link>http://scholarworks.umass.edu/open_access_dissertations/707</link>
<guid isPermaLink="true">http://scholarworks.umass.edu/open_access_dissertations/707</guid>
<pubDate>Thu, 21 Mar 2013 08:03:50 PDT</pubDate>
<description>
	<![CDATA[
	<p>Successful innovations have been assumed by prior literature to ultimately be adopted by all competitors within an industry based on social explanations or economic rationale specific to the efficiency of the innovation. However, capabilities possessed by a firm can enhance or inhibit the adoption based upon their similarity to those used in the innovation. In categorizing a firm's capabilities as complementary, substitutive, or neutralizing to the innovation, this study provides an economic explanation for the role of internal capabilities in adoption decisions.</p>
<p>Using a sample of professional football teams adopting the West Coast Offense, I find that capabilities influence the decision process in favor of adopting for organizations with complementary and substitutive capabilities. The role of knowledge from the innovator is highlighted in adopting the innovation, but fails to moderate the relationship between adoption and firm performance. I also illustrate how adopting firms with complementary capabilities outperform those organizations with similar capabilities that elect not to adopt. Finally, I demonstrate that firms with neutralizing capabilities are better off not adopting the innovation based on comparative performance of adopters and non-adopters. The overall results suggest a greater emphasis on internal capabilities of the firm in innovation adoption and reconsideration of theories stating that innovations should be adopted throughout an industry.</p>

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</description>

<author>Snyder, Kevin</author>

<source></source>

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<item>
<title>Bridging The Gap Between Autonomous Skill Learning And Task-Specific Planning</title>
<link>http://scholarworks.umass.edu/open_access_dissertations/706</link>
<guid isPermaLink="true">http://scholarworks.umass.edu/open_access_dissertations/706</guid>
<pubDate>Thu, 21 Mar 2013 07:53:54 PDT</pubDate>
<description>
	<![CDATA[
	<p>Skill acquisition and task specific planning are essential components of any robot system, yet they have long been studied in isolation. This, I contend, is due to the lack of a common representational framework. I present a holistic approach to planning robot behavior, using previously acquired skills to represent control knowledge (and objects) directly, and to use this background knowledge to build plans in the space of control actions.</p>
<p>Actions in this framework are closed-loop controllers constructed from combinations of sensors, effectors, and potential functions. I will show how robots can use reinforcement learning techniques to acquire sensorimotor programs. The agent then builds a functional model of its interactions with the world as distributions over the acquired skills. In addition, I present two planning algorithms that can reason about a task using the functional models. These algorithms are then applied to a variety of tasks such as object recognition and object manipulation to achieve its objective on two different robot platforms.</p>

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</description>

<author>Sen, Shiraj</author>

<source></source>

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<item>
<title>Circles and Lines: Complexities of Learning in Community</title>
<link>http://scholarworks.umass.edu/open_access_dissertations/705</link>
<guid isPermaLink="true">http://scholarworks.umass.edu/open_access_dissertations/705</guid>
<pubDate>Thu, 21 Mar 2013 07:46:15 PDT</pubDate>
<description>
	<![CDATA[
	<p>Following is a study that explores learning in community in a fully-integrated, team taught course at a community college in New England. These classes, Learning Communities (LCs) represent rich opportunities for exploring and practicing democratic education. From a theoretical grounding in social learning theories and an exploration into learning and community as active, ongoing phenomena, I present narrative, relational research as enactment. Data from field notes, interviews, focus groups and researcher reflections inform findings and analysis. I represent this as an experience parallel to -- not claiming either to mirror or replace -- the experiences of the other participants. In these findings, I identify a duality of circles and lines, with circles representing open inquiry, community, collaboration, and democratic discourse. Lines represent reification, hierarchical and binary thinking, and the threat of positivism. Long hours, intense interactions, openness to collaboration, flexible pedagogy, and emerging curriculum all make for complicated relationships that allow for questions, confusions and tensions around what it means to know, who gets to decide, and what are the parameters and epistemologies of academic disciplines. I hope, through this text, to report, celebrate, and participate in these conversations.</p>

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</description>

<author>Schupack, Sara Lynne</author>

<source></source>

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