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Title: NONLINEAR SIMULATIONS OF MULTI-VESICLE DYNAMICS
Creator: Hamiilton, Caleb
Date: 2015, 2015-07
Description: Vesicles in biology are closed forms of membranes. The dimensions of vesicles can vary in terms of surface area and enclosed volume. Examples...
Show moreVesicles in biology are closed forms of membranes. The dimensions of vesicles can vary in terms of surface area and enclosed volume. Examples range from small organelles to large cell bodies which all play a variety of resource transportation roles in biological systems. Research from the fields of chemistry and physics helps mathematical modeling by providing the mechanisms behind certain observed morphologies. Mathematical models and methods for simulating vesicle dynamics have produced accurate numerical solutions to verify experimental data and can be used to design new experiments that lead to more discoveries. The most researched case has been a single vesicle under shear flow. However, recent numerical and experimental results consider extensional flows on a single vesicle and hydrodynamic interactions among multiple vesicles. This thesis extends work on hydrodynamic interactions between vesicles in viscous fluid. We investigate numerically cases with multiple vesicles relaxing in asymmetrical configurations, time-dependent flow with more oscillation, and stochastic dynamics. Subjecting vesicles to these various cases reveals sensitivity to initial conditions such as distance and relative orientation. The effects from adding more vesicles are: increased time before equilibrium for the relaxation tests, and distributive wrinkling dynamics for the extensional flow tests. In stochastic cases, there are similar wrinkling distributions. However, initial conditions like distance and orientation have less important effects when competing with influence from thermal fluctuations. Additionally, in the presence of other vesicles under extensional flow, a vesicle may change the number and amplitude of wrinkles it would have experienced alone.
M.S. in Applied Mathematics, July 2015
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Title: Highway improvement in the state of Illinois
Creator: Sears, I. Lee
Date: 2009, 1915
Publisher: Armour Institute of Technology
Description: http://www.archive.org/details/highwayimproveme00sear
Thesis (B.S.)--Armour Institute of Technology; Includes "Contract form and general...
Show morehttp://www.archive.org/details/highwayimproveme00sear
Thesis (B.S.)--Armour Institute of Technology; Includes "Contract form and general specifications for bridge work"
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Title: POLARIZATION COUPLING IN SEMICONDUCTOR NANO-DIMERS IN THE TERAHERTZ RANGE
Creator: Hu, Zhijing
Date: 2017, 2017-05
Description: Surface plasmon resonance (SPR) occurs at the interface of a semiconductor and a dielectric when certain conditions are satisfied. SPR is...
Show moreSurface plasmon resonance (SPR) occurs at the interface of a semiconductor and a dielectric when certain conditions are satisfied. SPR is impetus to new sensor and device development in the optical range, with nanoparticles of noble metals taking up major roles. Typical conduction band electron concentrations in semiconductors lead to resonance frequencies in the terahertz and infrared bands. While the response strength is weaker than those exhibited by metals, it can be made up for by the formation of aggregates. The added degree of freedom by doping or carrier injection further enhances the versatility of semiconductor nanoclusters. To obtain a first principle solution to the coupled set of equations for charge carrier transport and electrodynamics in a conductive cluster is a formidable task with a high computational cost. Employing a finite-element based tool, the COMSOL Multiphysics Simulation Software, the interaction inside and outside some elementary semiconductor structures such as slab and sphere have been solved, which revealed the screening of the internal field while displaying dispersion and absorptions effects. The study of semiconductor dimer also showed a significant field enhancement and frequency shift. Under strong applied field, asymmetric polarization within the particles is revealed. The accompanying nonlinear polarization response can be employed to develop new devices. These model structures can serve to provide insight to the analysis and synthesis more complex structures.
Ph.D. in Electrical Engineering, May 2017
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Title: SALMONELLA SURVIVAL DURING INOCULATION AND STORAGE OF DRIED SPICES CONTAINING ANTIMICROBIAL COMPONENTS
Creator: Hu, Chuxuan
Date: 2016, 2016-05
Description: To provide an adequate initial microbial level for spices containing antimicrobial compounds for use in stability testing of foodborne...
Show moreTo provide an adequate initial microbial level for spices containing antimicrobial compounds for use in stability testing of foodborne pathogens, a dry-transfer inoculation was designed and compared with a traditional aqueous inoculation protocol. A five serovar cocktail of Salmonella spp. was prepared at different concentrations (~11 log CFU/mL, ~8 log CFU/mL and ~4 log CFU/mL). It was inoculated onto 1g silica beads and four types of dried ground spices (clove, oregano, ginger, and black pepper). Both spices and beads were dried for 24h at ambient conditions (~22°C). Silica beads were then used as a carrier to inoculate the same four types of spices. The results suggest that dry-transfer of Salmonella via inoculated silica beads provided a greater starting inoculum than aqueous transfer alone and are a viable alternative to aqueous inoculation when spices contain antimicrobial components. This dry-transfer inoculated ground clove with 8.4 log CFU/g and 3.9 log CFU/g initial populations was then used to determine the survival of Salmonella on spices containing antimicrobial components. Salmonella spp. survival on silica beads with 9.2 log CFU/g and 5.9 log CFU/g initial populations and subsequent transfer to ground clove was also examined. Samples were enumerated at selected time point up to 210 d. Results of this study indicate that Salmonella transfer and recovery from beads and in ground clove was not affect by storage and that Salmonella may persist for an extended period of time. The calculation of recovery was, however, affected by detection limits in clove. To improve detection limits an oil extraction was used and compared to the BAM method (detection limit 3.7 log CFU/g). After oil extraction the clove samples were soaked for 1 h (or 24 h for low inoculum concentration) in TSB at 37ᵒC and subsequently enumerated on tryptic soy agar with 0.6% yeast extract and xylose lysine deoxycholate agars. The result demonstrates that the oil extraction detection method holds promise as an alternative method to detect Salmonella in dry spices containing antimicrobial components and can provide a lower detection limit (1.7 log CFU/g).
M.S. in Food Process Engineering, May 2016
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Title: DESIGN OF INDUCTORLESS LOW NOISE AMPLIFIER
Creator: Huo, Yunsheng
Date: 2017, 2017-05
Description: With the rapidly increasing number of elements integrated on a single chip. The area on a chip became much costlier. And the difficulty of...
Show moreWith the rapidly increasing number of elements integrated on a single chip. The area on a chip became much costlier. And the difficulty of planning all the elements has been growing. So, decreasing the area cost of each single element became important to be considered. In the conventional technology, to cancel the imaginary part of the input impedance, inductors were used in the design of a LNA. However, inductor is an area consuming element, it would cost most of the chip area. To reduce the area cost of LNA, it is important to reduce the number of inductor, the best case is to design a LNA without any inductor. What’s more, without inductor, LNA would be able to work in a wideband frequency, but not a specific narrow-band frequency. But considering the imaginary part of input impedance, the highest frequency would reduce, depending on the f T of the MOSFET used in the design. In this thesis, the design considerations of heterodyne transceiver, which is the most popular architecture in modern RF design, are introduced firstly. Then, to reduce the undesired effect from image signal, a special architecture, called image-ejection architecture, is explained. To implement the proposal function, different architectures are shown. In RF receiver design, Low Noise Amplifier is one of the most important stages in the RX chain. To design a LNA which can meet different requirements of the RX design. Different topologies are explained, including CS stage, CG stage and differential LNA. Besides conventional technique, some up-to-date techniques are also shown, such as modified CG stage. The main propose of this thesis is to design an inductorless LNA. In this LNA design, Noise Canceling technology and Amplifier Enhancement technology were utilized to improve the noise and amplifying performance. After explaining the technologies theoretically, the circuit is simulated in a 65nm technology with working frequency band from 2 to 6 GHz. By the simulation, the gain of the design is beyond 14dB in the whole band, while the noise figure less than 2.8dB.
M.S. in Electrical Engineering, May 2017
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Title: A NANO-STRUCTURED CERAMIC/POLYMER COMPOSITE FILM FOR ELECTRONIC INTERCONNECTIONS
Creator: Harwath, Frank
Date: 2016, 2016-05
Description: Separable electrical interconnections are a ubiquitous part of modern life and for technical reasons are currently based on the use of gold....
Show moreSeparable electrical interconnections are a ubiquitous part of modern life and for technical reasons are currently based on the use of gold. Since gold is a commodity and subject to significant price fluctuations there is a need for separable interconnects not based on gold. Polymer/ceramic films were produced from various polymer precursors with loadings of multi-wall nanotubes (MWNT) and inert fillers. A variety of applications means were employed with the best success being achieved by means of a modified doctor blade. Pyrolysis was conducted in an inert atmosphere at 1 bar at a range of temperatures in a tube furnace. Pyrolysis was also conducted using a fiber laser. The modulus of the film is estimated to be 71.8 MPa with an ultimate tensile strength of 179 MPa based on hardness tests and anisotropic crack dimensions which developed as a result of uniaxial stress induced during application of the precursor. Uniaxial stress improved film adhesion regardless of filler type or level. Modification of film characteristics after pyrolysis was attempted using spark plasma sintering (SPS). Electrical testing displayed a percolation threshold above loadings of 1% (wt) of MWNTs where there is a significant drop in electrical resistivity. Further reductions in contact resistance were demonstrated up to 2% loading of MWNTs. The level of contact resistance achieved (<10) for a separable contact, in conjunction with a gold plated contact representative of most electronic connectors, indicates that an acceptable level of contact resistance may be achieved using these materials. Characterization of the film using attenuated total reflectance (ATR), xray diffraction (XRD), x-ray photoelectron spectroscopy (XPS), and Raman spectroscopy point to a morphology which is dominated by crystallites joined by regions of aliphatic carbon chains. Work function measurements were consistent with highly ordered pyrolytic graphite. (HOPG)
Ph.D. in Materials Science and Engineering, May 2016
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Title: COMMUNITY ENGAGEMENT AND COMMUNITY RESPONSE OF FIRST TIME CODE CONTRIBUTORS ON GITHUB
Creator: Heston, Matthew
Date: 2014, 2014-05
Description: We collect data for 13,383 rst time code contributions from 45 projects on the website GitHub and analyze behavior of developers before...
Show moreWe collect data for 13,383 rst time code contributions from 45 projects on the website GitHub and analyze behavior of developers before submitting code as well as community response to code contributions. Our ndings di er from previous research on open source software communities and social theories of learning in communities of practice. We nd most users do not participate in GitHub peripheral activities before submitting code changes. We also nd that community response to these submitted code changes is a poor predictor of whether or not the code is accepted.
M.S. in Information Architecture, May 2014
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Title: CRITICISM, HEALTH FUNCTIONING, AND MARITAL ADJUSTMENT IN COUPLES WITH CARDIOVASCULAR DISEASE
Creator: Hicks, R. Elliott Iii
Date: 2017, 2017-07
Description: Destructive communication and hostile interactions between spouses are associated with poor behavior maintenance and can elicit substantial...
Show moreDestructive communication and hostile interactions between spouses are associated with poor behavior maintenance and can elicit substantial increases in systolic blood pressure, heart rate, and cardiac output in patients (Broadwell, & Light, 2005; Nealey-Moore et al., 2007; Ryan & Deci, 2000). This negatively impacts the cardiovascular health of the targeted partner (Nealey-Moore et al., 2007; Ryan & Deci, 2000; Smith et al., 2009). Constructive, non-hostile criticism between partners may bolster behavior change and maintenance (Zinbarg, 2007). The present study assesses the relationship between forms of criticism and reports of marital adjustment, autonomous support, health functioning, and health behavior change in a sample of couples participating in a cardiac risk reduction intervention. Results indicate that Hostile Criticism predicted Physical Health Functioning. Further, there were no significant moderating relationships. Interpretation of results and future directions are discussed.
Ph.D. in Psychology, July 2017
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Title: FROM EXPLORATION TO RATIONAL DESIGN OF SELECTIVE PROPANE DEHYDROGENATION CATALYSTS
Creator: Hu, Bo
Date: 2015, 2015-12
Description: Light olefins, e.g., ethene and propene, are important building blocks of chemical industry for the production of fuels, polymers, lubricants...
Show moreLight olefins, e.g., ethene and propene, are important building blocks of chemical industry for the production of fuels, polymers, lubricants and other fine chemicals. Due to the rapidly increasing production of shale gas, conversion of small alkanes in the shale gas, e.g., ethane and propane, to their corresponding olefins via alkane dehydrogenation could be an important industrial process. This thesis has focused on exploring the novel single site heterogeneous catalysts for selective alkane dehydrogenation and investigating the general principles of rational catalyst design to achieve a better performing (e.g., more active, more stable, highly selective) dehydrogenation catalyst. Based on the observed reactivity of ZnO for olefin hydrogenation and activity of Zn-ZSM-5 catalysts for alkane activation, catalytic properties of isolated Zn2+ were first explored for propane dehydrogenation. The 3-coordinate Zn in single site Zn/SiO2 catalyst was demonstrated to be the catalytically active species that was highly selective for the generation of propene by propane dehydrogenation. DFT calculations revealed that slow β-hydride elimination of alkyl intermediates limited the overall activity of single site Zn/SiO2 catalyst. Thus, single site Co/SiO2 was also prepared in order to take the advantage of fast β-hydride elimination. The higher activity of single site Co/SiO2 emphasized the potential of transition metals for alkane dehydrogenation, and propane dehydrogenation reactivity of transition metals was further explored by investigating single site Fe/SiO2 catalyst. By comparing with metallic Fe nanoparticles and bulk phase Fe oxides catalysts, the 3-coordinate single site Fe2+ was also suggested to be the catalytically active species for selective propane dehydrogenation. However, the catalytic activity of single site Fe/SiO2 catalyst was lower than that of Zn/SiO2. Such result suggested heterolytic cleavage of C-H bonds was slow for transition metals, e.g., Co and Fe, due to their weak Lewis acidity, and it may mitigate the advantages gained in rapid β-hydride elimination. An exploration of ligand effects for improving heterolytic cleavage over single site heterogeneous catalysts was performed. The strength of metal oxygen bond governed by ligand electron donating effects and ligand basicity were found to be the critical chemical descriptors for a facile heterolytic cleavage. Those observed principles of ligand effects would lead to a new strategy of rational catalyst design for a superior dehydrogenation catalyst.
Ph.D. in Chemistry, December 2015
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Title: A KINETIC MODEL TO ESTIMATE VASCULAR PERMEABILITY FROM FLUORESCEIN VIDEOANGIOGRAPHY DATA
Creator: Hu, Shaoxian
Date: 2017, 2017-05
Description: Diabetic retinopathy (DR) is a disease affecting the tissue of the retina through hemodynamics and vascular damage that is a side effect of...
Show moreDiabetic retinopathy (DR) is a disease affecting the tissue of the retina through hemodynamics and vascular damage that is a side effect of hyperglycemia. As such, markers of hemodynamic and vascular irregularity have been proposed as potential early indicators of the disease. However, conventional approaches to estimate these conditions are not sensitive enough, leading to indications that are too late, appearing only after irreversible vision problems have occurred. Indicator-dye-dilution tracer kinetic modeling is a decades-old methodology that can be used to quantify blood flow and vascular permeability based on the kinetics of a rapidly injected blood pool imaging agent. The methodology is able to track sensitive hemodynamic changes in stroke and heart disease patients, yet it has never been applied to blood flow and vascular permeability mapping of the retina. The purpose of my Master’s thesis was to adapt those tracer kinetic methods to fluorescein retinal videoangiography data collected in human to map both blood flow and vascular permeability so that in future work, changes in these parameters can be quantified at varying stages of the development of DR. Studies were carried out on simulated data, healthy and diabetic rats, and healthy and diabetic humans. While a robust validation of measures of blood flow and vascular permeability are still required, this first-of-its-kind study exposed many unique complications in applying the kinetic models to human fluorescein videoangiography data. Specifically, eye motion must be accounted for, both detector and fluorescein fluorescence quenching signal saturation must be avoided, and standard use of automatic gain control of imaging exposure should not be used (though corrections were developed for this); rather, data should be collected at a stable exposure throughout a measurement. Solutions were developed for all of these complications that were tested in rat models (optimal data collection in humans is ongoing). In rat study, average vascular permeability in the rat measured by the “extraction fraction”, the extraction fraction in control subject (n=3) 9.4e-4±1.3e-3, is lower than STZ-diabetic subjects (n=3) 5.5-2±5.17e-2 and VEGF group (n=3) 7.6e-2±5.1e-2. In healthy human volunteers, retinal extraction fraction was measured to be 5.0e-5 ± 6.1e-5 (n=2), whereas this was found to be elevated to 1.2e-3 ± 1.0e-3 in patients for diagnosed DR (n=3). These early results clearly demonstrated a statistically significant elevation in vascular permeability in all diabetic groups compared to controls (p<0.05). The human study was carried out on advanced cases of patients who were known to have DR as a test case; however, the sensitivity of the approaches is demonstrated by the eatly changes in extraction fraction observed at only 48 h after the onset of hyperglycemia in the rat experiments (well before irreversible damage to the retina had occurred). These results are promising for the adaptation of our modified kinetic modeling approach to measure hemodynamics and vascular permeability changes during the early onset of DR when preventative therapies could be most effective.
M.S. in Biomedical Engineering, May 2017
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Title: INDEX CODING VIA RANK MINIMIZATION
Creator: Huang, Xiao
Date: 2015, 2015-07
Description: Index codes reduce the number of bits broadcast by a wireless transmitter to a number of receivers with different demands and with side...
Show moreIndex codes reduce the number of bits broadcast by a wireless transmitter to a number of receivers with different demands and with side information. It is known that the problem of finding optimal linear index codes is NP-hard (a worst-case result). Many heuristic solutions based on graph coloring have been proposed. However, graph coloring is also a NP-hard problem, and it only gives an upper bound of the index coding. Motivated by a connection between index coding and rank minimization, this thesis investigates the performance of different heuristics based on rank minimization and matrix completion methods, such as alternating projections and alternating minimization, for constructing linear index codes over the reals. The underlying matrices representing an index coding problem have a special structure that makes celebrated methods, such as nuclear norm minimization, perform badly. The performance of different methods, such as alternating projections, directional alternating projections and alternating minimization are presented, through extensive simulation results on random instances of the index coding problem. This thesis makes the following contributions: 1) The proposed alternating projections method gives the best performance compared to other graph based algorithms in the literature. 2) This proposed method leads to up to 13% savings on average communication cost compared to the well know greedy graph coloring algorithm. 3) The thesis describes how the proposed methods can be used to construct linear network codes for non-multicast networks. Our computer code is available online.
M.S. in Electrical Engineering, July 2015
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Title: MODELING THE IMPACT OF NATURAL GAS VARIATION ON COMBUSTION IN A DUAL FUEL ENGINE
Creator: Hulbert, Matthew Calvin
Date: 2017, 2017-07
Description: The desire to meet rising energy demands while simultaneously adhering to stringent climate policies have propelled several advanced...
Show moreThe desire to meet rising energy demands while simultaneously adhering to stringent climate policies have propelled several advanced combustion technologies. The utilization of alternative fuels in internal combustion engines is a relevant solution to the immediate problems facing the transportation sector. Natural gas (NG) is an attractive alternative as it is economically and environmentally versatile, geographically diverse, and has clean-burning qualities which when coupled with dual fuel technologies has shown significant positive impacts on combustion characteristics. The present work describes the setup of an experimental test cell that contains a modern 2.0-liter 4-cylinder turbocharged direct-injected diesel engine that will be modified for dual fuel capability. The initial stages of a computationally efficient simulation model that represents the experimental engine are also presented and a discussion on the model’s development ensues. A dual fuel simulation model was created and calibrated against experimental data obtained from a heavy-duty 6-cylinder duel fuel engine. The objective of this work is to assess the affects different NG compositions have on the combustion process. Natural gas has shown to vary significantly, depending on where the fuel is acquired. The results show that methane content plays a significant role on combustion. As methane content increases, start of combustion (SOC) shifts and peak cylinder pressure decreases. The premixed combustion phase is shown to increase with decreasing methane content, while the mixing-controlled combustion phase decreases. Nitrogen oxides (NOx), carbon monoxide (CO), and carbon dioxide (CO2) emissions have demonstrated to be dependent on methane content. NG compositions with low methane content show increased amounts of CO2 emissions while high methane content shows a decrease in nitric oxide (NO) emissions.
M.S. in Mechanical and Aerospace Engineering, July 2017
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Title: TEXT MESSAGE REMINDERS AND TREATMENT ADHERENCE IN A TYPE II DIABETES POPULATION: A FEASIBILITY STUDY
Creator: Kramer, Alexis J.
Date: 2014, 2014-05
Description: Type II Diabetes (T2DM) is a chronic disease effecting millions of people worldwide. It is well documented that lifestyle changes including...
Show moreType II Diabetes (T2DM) is a chronic disease effecting millions of people worldwide. It is well documented that lifestyle changes including adherence to treatment regimens (e.g. glucose monitoring) can be very effective in reducing the onset and progression of T2DM. The literature suggests that individuals within this population are often non-compliant with treatment recommendations, for a variety of reasons (e.g. psychological factors, availability of resources, co-morbid conditions). The purpose of this study was to investigate the suitability, recruitment and retention feasibility, and preliminary outcomes of a text message reminder system on treatment adherence within a type 2 diabetic population, as measured by blood glucose levels (HbA1c). A total of 28 participants were randomized into experimental or no-treatment conditions. Participants in the experimental group received text message reminders on either a fixed or variable schedule; with either neutral or calming test message content. They also completed a qualitative feedback measure, to assess participant satisfaction with the proposed intervention. Participants in the no-treatment condition did not receive any text message reminders. All participants completed the Diabetes Care Profile (DCP) and Short Form-36 Health Form Survey, Version 2 (SF-36v2) at baseline and three months later (time 2). Preliminary analyses show that frequency of text message reminder significantly impacted glucose levels over time. The content of the text message was not shown to have a significant effect on glucose levels. Participant perception of the proposed intervention was mixed. Despite diverse recruitment efforts, recruitment was low, however, retention was high.
PH.D in Psychology, May 2014
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Title: SHARED LEADERSHIP EFFECTIVNESS IN FACE-TO-FACE AND VIRTUAL CONDITIONS: A SOCIAL NETWORK ANALYSIS
Creator: King, Adrienne
Date: 2013, 2013-12
Description: The purpose of this study was to investigate the relationship between shared leadership, performance, and team affect across two communication...
Show moreThe purpose of this study was to investigate the relationship between shared leadership, performance, and team affect across two communication-medium conditions: face-to-face and virtual interactions. After completing the “Lost-at-Sea” (Nemiroff & Pasmore, 1975) exercise, undergraduate students in leaderless teams (N = 75) of three reported their experiences and evaluated team members’ interactions and behaviors. Based on the functional leadership theory (McGrath, 1962), shared leadership was described by task and socio-emotional behaviors, and measured through social network analysis. Regression analysis revealed shared leadership’s positive influence on group affect and the condition’s impact on objective standards of performance. A follow-up mediational analysis revealed that team affect had a significant impact on the relationship between shared leadership and decision time. Additionally, post hoc analysis revealed that the level of shared leadership was higher in face-to-face teams, compared to teams in the computer-mediated condition. A discussion of the results and implications for practice are provided. In conclusion, this study highlights the importance of using shared leadership teams in modern organizations.
M.S. in Industrial / Organizational Psychology, December 2013
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Title: THE EFFECT OF NANOPARTICLE SELF-STRUCTURING ON WETTING AND SPREADING OF NANOFLUIDS ON SOLID SURFACES
Creator: Kondiparty, Kirtiprakash
Date: 2011-11, 2011-12
Description: Nanofluids are suspensions of nanometer-sized particles in liquids. The nanoparticles self-structure at the three-phase contact region...
Show moreNanofluids are suspensions of nanometer-sized particles in liquids. The nanoparticles self-structure at the three-phase contact region resulting in the structural disjoining pressure gradient which causes enhanced the spreading of nanofluids compared to simple fluids without nanoparticles. In this thesis, we attempt to understand the effect of the structural disjoining pressure on the spreading dynamics of nanofluids on solid surfaces. We observed nanoparticle self-structuring phenomena during film thinning on a smooth hydrophilic glass surface using a silica-nanoparticle aqueous suspension and reflected light interferometry. Our experiments revealed that film formed from small drop is thicker and contains more particle layers than a film formed from large drop. The data for the film-meniscus contact angle verses film thickness were obtained and used to calculate the structural energy isotherm of an asymmetric film. We studied the effect of structural disjoining pressure on the wedge meniscus profile formed by an oil drop on solid surface surrounded by nanofluid using Laplace Equation augmented with the structural disjoining pressure. Our analyses indicate that a suitable combination of the nanoparticle concentration, nanoparticle size, contact angle, and capillary pressure can result not only in the displacement of the three-phase contact line, but also in the spontaneous spreading of the nanofluid as a film on solid surface. We validated our theoretical predictions using experiments where we observed spreading of nanofluid on glass surface displacing a sessile drop of canola oil. The dynamic spreading of the nanofluid on a solid surface between a sessile oil drop on solid surface was experimentally measured using reflected light microscopy. We xiv obtained the rate of nanofluid spreading by plotting the position of the inner contact line with time. The nanofluid film was found to spread at a constant velocity. We modeled the spreading dynamics of the nanofluid film using the lubrication approximation of the Navier-Stokes Equation, taking into consideration the structural disjoining pressure in the over-all pressure balance. The model was evaluated by estimating the rate of nanofluid spreading for the 10v% nanofluid. The rate of spreading thus predicted by the dynamics model for 10v% nanofluid was in good agreement with the experimental observations.
Ph.D. in Chemical Engineering, December 2011
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Title: INVESTIGATING THE IMPACT OF EDUCATION AND CONTACT-BASED ANTI-STIGMA INTERVENTIONS ON THE STIGMA OF MENTAL ILLNESS IN THE COLLEGE POPULATION
Creator: Kosyluk, Kristin
Date: 2014, 2014-12
Description: Approximately one in four college students screen positive for a mental illness, however many who might benefit from mental health care do not...
Show moreApproximately one in four college students screen positive for a mental illness, however many who might benefit from mental health care do not seek treatment. Amongst both the general adult population and college students, stigma has been shown to be a predictor of treatment engagement, with higher levels of stigma with regard to mental illness predicting lower levels of treatment utilization. It has been demonstrated in the general adult population that contact-based anti-stigma programs are the most effective approach to stigma change, followed by education-based programs. This study aimed to investigate the impact of contact- and education-based anti-stigma interventions, relative to a control condition, on mental illness stigma, affirming attitudes towards individuals with mental illness, discrimination towards individuals with mental illness, and treatment seeking amongst college students. Both contact- and education-based interventions were found to have a significant impact on personal stigma, perceptions of empowerment, desired social distance from individuals with mental illness (a proxy of discrimination), attitudes towards treatment seeking, and intentions to seek treatment from formal sources of support. No difference in effect was demonstrated between the contact- and education-based conditions. These findings suggest that these two approaches may be equally effective for challenging stigma amongst college students.
Ph.D. in Psychology, December 2014
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Title: NEUROPATHOLOGIC CORRELATES OF BRAIN MACROSTRUCTURE
Creator: Kotrotsou, Aikaterini
Date: 2014, 2014-07
Description: Alzheimer’s disease, the most common form of dementia, is a degenerative disorder of the brain that leads to memory loss. Clinical diagnostic...
Show moreAlzheimer’s disease, the most common form of dementia, is a degenerative disorder of the brain that leads to memory loss. Clinical diagnostic techniques in use today rely on mental and behavioral tests and physical examinations and only provide diagnoses of possible or probable Alzheimer’s disease. However, lately it has become clear that clinical-pathological correspondence is not always consistent. A definitive diagnosis of Alzheimer’s disease is only possible via histology, when the density of neurofibrillary tangles and amyloid plaques is measured. Therefore, the development of a reliable neuroimaging technique that allows detection of Alzheimer’s pathology during life is needed. This method would be noninvasive, and could allow the detection of Alzheimer’s disease in the early stages, and could be also used to monitor the progression of the disease through time. The purpose of this work was to investigate the use of magnetic resonance imaging (MRI) as diagnostic tool for Alzheimer’s pathology and other age-related neurodegenerative pathologies that are common in older persons. To uncover the anatomical origins and determine the macrostructural signatures of age-related neuropathologies, it is necessary to link MRI findings with pathologic information on the same individuals. In this work, we focused on imaging cerebral hemispheres ex-vivo, when a complete pathology report was available from a board-certified neuropathologist. The main difference between this work and any other study is the abundance of postmortem imaging data paired with neuropathology data in a relatively large pool of subjects. First, we developed and validated a protocol to perform ex-vivo MR volumetry. By using this protocol we observed the longitudinal behavior of the volume of different brain regions. Furthermore, we tested the hypothesis that volumetric measurements performed ex-vivo are associated with in-vivo measurements. It was shown that: (a) regional brain volumes measured with this approach for ex-vivo MR volumetry remain relatively unchanged for a period of 6 months postmortem, and (b) a linear correspondence was detected between in-vivo and ex-vivo measurements, suggesting that this approach captures information linked to antemortem macrostructural brain characteristics. Using the approach for ex-vivo MR volumetry, we combined ex-vivo MR volumetry with pathology on the same adults. AD pathology was significantly negatively correlated with volumes of cortical gray matter regions, mainly in the temporal, frontal, parietal and cingulate cortices, subcortical gray matter, and whole-hemisphere white matter. A significant negative correlation was shown between hippocampal sclerosis and volumes of the hippocampus, as well as other temporal and frontal gray matter regions. Finally, we performed a morphometric MRI study to investigate associations of brain volumes with pathology using voxel-based analysis. This technique allows the assessment of gray and white matter volumes in subjects with different pathologies compared with controls in an automated fashion, across the whole brain. AD pathology was negatively associated with regions of gray matter and white matter located in temporal and frontal lobes, and orbitofrontal cortex. This work examined the associations of brain volumes with Alzheimer’s pathology and other typed of age-related neurodegenerative pathologies. Combining histological result with MR images requires that the time elapsed between imaging and histology is minimal. Ex-vivo MRI provides images at essentially the same time-point as histological examination of the tissue, and this study is unique in that it involves a large number of cadaveric brain hemispheres. The findings of this ex-vivo study could allow for future standardization of MRI as a biomarker of neurodegenerative diseases, and also allow in identification and classification of subjects in groups for tests of new drugs.
Ph.D. in Biomedical Engineering, July 2014
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Title: MODERATING EFFECT OF MINDFULNESS IN THE RELATIONSHIP BETWEEN CARDIOVASCULAR DISEASE RISK FACTORS
Creator: Kim, Jeong Hye
Date: 2016, 2016-07
Description: Cardiovascular diseases (CVDs) are the leading cause of death worldwide and in the United States. Weight loss, which is associated with blood...
Show moreCardiovascular diseases (CVDs) are the leading cause of death worldwide and in the United States. Weight loss, which is associated with blood pressure and blood glucose, is widely recommended to modify the CVDs risk factors. Among various methods, mindfulness has been extensively studied in improving psychological and physical health. There is some reported evidence that mindfulness based interventions are effective in improving CVDs risk factors. However, overall results are inconclusive. Therefore, more research examining the facets of mindfulness is necessary to understand the fundamental relationship between mindfulness and CVDs risk factors to clarify the effect of mindfulness. In addition, research into whether the relationship between different risk factors is moderated by mindfulness would provide further support of the independent effect of mindfulness on physical health. The current study hypothesized that higher mindfulness skills would correlate with physical well-being. Furthermore, it was hypothesized that mindfulness will moderate a relationship between BMI and other CVDs risk factors (e.g., individuals with higher BMI classification and higher mindfulness will show lower blood pressure compared to individuals at a similar BMI with lower mindfulness). Results found that body adiposity had an inverse relationship with overall mindfulness, and two of the four facets of mindfulness (Describing and Acting with awareness). In addition, the Describing subscale had a significant moderating effect; however, the relationship between body adiposity and systolic blood pressure was stronger rather than weaker with higher Describing skills.
M.S. in Psychology, July 2016
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Title: DEVELOPMENT OF ADVANCED PACKAGING, FABRICATION AND RELIABILITY METHODS FOR SUBMINIATURE IMPLANTABLE NEURAL PROSTHESES
Creator: Kim, Taehyung
Date: 2011-08, 2011-07
Description: The main purpose of the present thesis is to study the critical reliability issues of polymeric encapsulated electronic devices for visual...
Show moreThe main purpose of the present thesis is to study the critical reliability issues of polymeric encapsulated electronic devices for visual prosthesis. Visual prosthesis has been compatibly studied over twenty years in many professional research labs. The electric design of circuit for the visual prosthesis has been well studied so far. However, the device packaging design and reliability have been not studied extensively. In particular, failure analysis and reliability using non-hermetic packaging for long lifetime visual prosthesis have been poorly studied. The first step of the research for this thesis was to create a mechanical design of a visual prosthesis prototype. The prototype device was created by fabricate a multi-layer structure consisting of electrodes, substrate, and integrated circuit chip with silicone encapsulated packaging. The interconnection between the chip and electrodes used Au wire and Al bonding pad. The prototype devices were tested in a liquid water. This water environment is not a common reliability test for commercial electronic packaging. Relative humidity testing is a common and widely used testing methods, but the visual prosthesis device cannot be applied to gas phase relative humidity testing due to the environment condition. Water absorption in polymeric material in the liquid water is higher than in the vapor water. After water penetrated interconnection interface, the Au-Al intermetallic compound becomes oxidized and generates bonding die open failure. From these unusual testing results, we were conformed the failure mechanism and predicted the lifetime using Au-Al imtermetallic growth pattern and oxidation. Additional discussions include transition metal ions in CSF to expect the other failure mechanisms. Wafer and packaging level xiii failure mechanisms by Cu and Fe ions are also discussed in this thesis. The end of this thesis discuss possible fabrication processing to protect overall external environment effects for polymeric packaging visual prosthesis. Overall this thesis study, which uses polymeric packaging electronic devices for bio-implant research, concluded that devices may not make good reliability devices in the CSF environment. The corrosion, oxidation and metallization on or in metal surfaces and interconnection interfaces should continually be studied to produce longer lasting electronic devices over 30 years. The reliability of the visual prosthesis has not been well studied in any other professional research labs, so this thesis may give or address some initial guidelines to help save time for the project decision in the future to develop advanced hermetic packaging for bioimplantable electronic devices.
Ph.D. in Materials Science and Engineering, July 2011
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Title: BLADE PITCH OPTIMIZATION METHODS FOR VERTICAL-AXIS WIND TURBINES
Creator: Kozak, Peter
Date: 2016, 2016-07
Description: Vertical-axis wind turbines (VAWTs) offer an inherently simpler design than horizontal-axis machines, while their lower blade speed mitigates...
Show moreVertical-axis wind turbines (VAWTs) offer an inherently simpler design than horizontal-axis machines, while their lower blade speed mitigates safety and noise concerns, potentially allowing for installation closer to populated and ecologically sensitive areas. While VAWTs do offer significant operational advantages, develop- ment has been hampered by the difficulty of modeling the aerodynamics involved, further complicated by their rotating geometry. This thesis presents results from a simulation of a baseline VAWT computed using Star-CCM+, a commercial nite volume (FVM) code. VAWT aerodynamics are shown to be dominated at low tip- speed ratios by dynamic stall phenomena and at high tip-speed ratios by wake-blade interactions. Several optimization techniques have been developed for the adjustment of blade pitch based on finite-volume simulations and streamtube models. The effectiveness of the optimization procedure is evaluated and the basic architecture for a feedback control system is proposed. Implementation of variable blade pitch is shown to increase a baseline turbine's power output between 40%-100%, depending on the optimization technique, improving the turbine's competitiveness when compared with a commercially-available horizontal-axis turbine.
Ph.D. in Aerospace and Mechanical Engineering, July 2016
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