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Title: An adaptive personalized multivariable, multimodule artificial pancreas system based on a plasma insulin cognizant model predictive control
Creator: Hajizadeh, Iman
Date: 2019
Description: An adaptive and personalized multivariable artificial pancreas system is proposed for effective glycemic control and disturbance rejection...
Show moreAn adaptive and personalized multivariable artificial pancreas system is proposed for effective glycemic control and disturbance rejection without manual user announcements for meals and exercise. Adaptive models identified through system identification techniques are integrated with a physiological compartment model to characterize the time-varying glucose-insulin dynamics. The real-time estimation of plasma insulin concentration to quantify the insulin in the bloodstream in patients with type 1 diabetes mellitus is presented. The identified time-varying models are employed for the design of an adaptive model predictive control formulation that is cognizant of the plasma insulin concentration. A feature extraction method based on glucose measurements is used to detect rapid deviations from the desired set-point caused by significant disturbances and subsequently modify the constraints of the optimization problem for negotiating between the aggressiveness and robustness of the controller to suggest the required amount of insulin. A predictive hypoglycemia module with carbohydrate suggestion is also designed to prevent any potential hypoglycemia events. A controller performance assessment algorithm is developed to analyze the closed-loop behavior and modify the parameters of the artificial pancreas control system. To this end, various performance indices are defined to quantitatively evaluate the controller efficacy in real-time. The controller assessment and modification module also incorporates on-line learning from historical data to anticipate impending disturbances and proactively counteract their effects.
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Title: Electron Cloud studies at Fermilab
Creator: Ji, Yichen
Date: 2019
Description: The presence of unwanted electrons in an accelerator vacuum chamber, known as E-cloud (E-cloud) can potentially cause operational problems in...
Show moreThe presence of unwanted electrons in an accelerator vacuum chamber, known as E-cloud (E-cloud) can potentially cause operational problems in the Fermilab Main Injector (MI) and Recycler Ring (RR). E-cloud has caused instability in the RR in the past, and although it is not currently a problem, there is measurable E-cloud in the MI accelerator. There are planned beam intensity increases due to upgrades of the Fermilab accelerator complex, so E-cloud could become a problem. Some work has been done by others previously to understand how low SEY (Secondary Electron Yield coefficient) coatings might mitigate production of E-cloud, and to model the mechanism whereby E-cloud causes beam instability. Using previous studies as a base, this research took several approaches toward understanding the risk of E-cloud at Fermilab. The evolution of the SEY of the SS316L (stainless steel), TiN coated SS316L, and amorphous carbon coated SS316L were measured in-situ using a SEY measurement station in the MI tunnel. The SEY of these materials change over time either due to bombardment of the E-cloud, or disruption of vacuum conditions. The SEY evolution was tracked over a several year period to find out how long it takes for the SEY of each material to reach its lowest level, and how much the SEY rises during deconditioning periods of poor vacuum. The SEY measurement results can be used to determine whether the SS316L will be a problem at upgrade intensities, and if so, whether or not TiN and A-Carbon coatings can mitigate E-cloud related problems sufficiently. Direct measurements of the E-cloud were done as well, and compared to simulation. The E-cloud bombardment rate was measured at different beam intensities and bunch lengths. It was possible to get detailed information on how the E-cloud varies over the acceleration cycle, where sensitivity to bunch length is reflected in the evolution of the E-cloud. The Retarding Field Analyzer (RFA) measuring the E-cloud bombardment rate was near the instrument that is used to measure the SEY of the beam pipe material. This proximity provided an accurate SEY value for simulations, so that the simulated E-cloud bombardment rate could be better compared to measurement. Bunch length measurements and computations generated accurate bunch length information also needed as input for simulations. After this careful control of the input parameters, the POSINST simulations of E-cloud were a good match to direct measurements. This gave confidence that predictions could be made concerning the E-cloud densities at upgrade intensities. These densities were compared against corresponding proton densities to predict the SEY required to avoid instabilities. That prediction and the information provided by the SEY measurements provide helpful information regarding the risks of E-cloud effects at future beam intensities at Fermilab.
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Title: Measuring Maternal-Fetal Attachment: Model Fit and Measurement Invariance of a New Assessment Tool
Creator: Hedrick, Laura
Date: 2019
Description: The importance of studying Maternal-Fetal Attachment (MFA) as part of the system of maternal-child perinatal functioning is well established...
Show moreThe importance of studying Maternal-Fetal Attachment (MFA) as part of the system of maternal-child perinatal functioning is well established in the literature, as MFA relates to health-related and psychosocial variables both during pregnancy and after the infant is born (e.g., positive health behaviors in pregnancy; levels of maternal stress, anxiety, and depressive symptoms; positive parenting behaviors after the child is born; and secure infant attachment at age one year). Despite the apparent value of studying MFA, there is no acceptable measurement tool for the construct. Existing assessment tools often do not meet minimum psychometric standards, may not be practical for broad research application, and have demonstrated inconsistent results in correlational research. Therefore, a clear need exists for a measurement scale with strong psychometric properties that is based on empirically supported development strategies. The present line of research sought to fill this need. The process of developing a new measurement tool began in a previous study, Hedrick (2015), which used Exploratory Factor Analyses to identify options for a potential measurement scale from subsets of a large pool of items intended to measure MFA. In Hedrick (2015), three options were identified as acceptable, then compared based on ranges of communalities, percentage of variance explained, internal consistency, and performance on two measures of concurrent and discriminant validity. However, these assessments failed to differentiate a single option as most preferable. Therefore, the first aim of present study was to complete the task of differentiating among the working measures to choose a measurement scale. Confirmatory Factor Analysis (CFA) was used to attempt to determine which working measure from the EFA study had the factor structure that fit best in a second sample of participants. The CFA process was not able to differentiate a superior working measure from the options. Therefore, the most theoretically sound of the three was chosen to use as a measurement tool, with some small adjustments made based on the CFA results. To continue to establish the validity of the new questionnaire measure, the second aim of the study was to assess its measurement invariance among different administration methods and populations. The measurement tool was found to be non-invariant in both areas. Specifically, the results of the measurement invariance analyses indicated that the measure should be administered on paper rather than online, would be best applied in research in African American/Black populations than in research with other racial/ethnic groups, and should not be used to compare MFA scores among racial/ethnic groups. Measurement invariance analyses also revealed that the scale was non-invariant at the metric level regarding parity groups. The implications of these findings for further research is discussed.
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Title: Security analysis in device-to-device wireless networks
Creator: Liu, Kecheng
Date: 2019
Description: Device-to-device (D2D) network has now become a standardized feature in many mobile devices, by which mobile devices can communicate with each...
Show moreDevice-to-device (D2D) network has now become a standardized feature in many mobile devices, by which mobile devices can communicate with each other even when internet access is not available. Because D2D network is expected to be an intrinsic part of the Internet of Things (IoT) and mobile device is the smartest and the most advanced commercial device in everyday usage, the D2D feature and related security protocols can influence the design and implementation of many other IoT devices. While D2D network provides tangible benefits to users, it also raises the security risks of information leaking. Our work performs an in-depth systematical security analysis on 802.11 based D2D network among commercial devices, including personal mobile devices such as phones and tablet, as well as business POS and printers. In this paper, we focus on most popular apps in the Google Play Store, the best selling printers in the market and the most widely adopted commercial POS devices for small businesses. Our analysis reveals some critical vulnerabilities. The key findings are multi-fold. First, the current mobile D2D network framework established on 802.11 protocol has significant flaw of over-privileged issue. Second, we have identified that data transfer over D2D network can be eavesdropped. Furthermore, we exploit the identified framework flaws to construct multiple proof-of-concept attacks and we conclude the paper with security lessons and suggestions of possible solutions against the identified security issues.
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Title: SODIUM-BASED ENERGY METABOLISM AND DYNAMIC ENERGY DEPENDENCY OF CHLAMYDIA TRACHOMATIS
Creator: Liang, Pingdong
Date: 2019
Description: Chlamydia trachomatis is an obligate intracellular bacterium that is responsible for various human diseases including trachoma, genital tract...
Show moreChlamydia trachomatis is an obligate intracellular bacterium that is responsible for various human diseases including trachoma, genital tract infections, and lymphogranuloma venereum. Energy metabolism consists many essential pathways to generate energy for every organism. However, it remains much unknown in C. trachomatis. For decades, C. trachomatis has been considered as an “energy parasite”, which needs the energy supply from the host cells entirely. In contrast, genomic studies show that this bacterium is capable of encoding enzymes that involve energy metabolism. However, no experimental data were provided to support the genomic information due to the peculiar developmental cycle of C. trachomatis inside the host cells. In this project, the oxidative phosphorylation pathway of C. trachomatis is first identified with experimental results. This pathway starts with the sodium pumping NADH:Ubiquinone oxidoreductase enzyme complex (NQR) transferring the electrons along the respiratory chain and generating a sodium gradient across the membrane. C. trachomatis contains an A-type ATPase that can utilize this sodium gradient to generate ATP. In vitro experiments in mammalian cells with different respiratory inhibitors show that C. trachomatis is not an obligate energy parasite. Instead, it has a dynamic energy dependency on the host metabolism that the bacterium switches from entirely to partially relying on the host energy metabolism for its energy requirement. The sodium gradient established by NQR and/or other transporters is of great importance to chlamydial metabolism. Further, the respiratory inhibitors test on interferon-γ-induced persistence of C. trachomatis in mammalian cell cultures shows that an inhibited energy metabolism prevents and eliminates the persistent form. This study provides new insights about antibiotics development and therapeutic methods against C. trachomatis infections.
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Title: Silkworm silk - CNT composite fibers: fabrication, characterization and application in cell stimulation for tissue regeneration
Creator: Zheng, Shuyao
Date: 2019
Description: Silk fibroin, a structural protein of the Bombyx mori cocoons, is widely studied for biomedical applications because of its strong mechanical...
Show moreSilk fibroin, a structural protein of the Bombyx mori cocoons, is widely studied for biomedical applications because of its strong mechanical property, biocompatibility, low degradation rate and ease of processing. In this study, we incorporated functionalized CNT in silkworm silk proteins to generate biocomposite fibers by electrospinning. The electro-spun (E-spun) fibers were unidirectionally aligned with a diameter at the sub-micrometer scale, mimicking the locally oriented ECM proteins in native tissues. The addition of a minute amount of CNT not only reinforced the stability and the mechanical strength of the flexible scaffolds, but also rendered the fibers electrical conductivity to not only facilitate the E-spun fiber formation but also grant the fibers an additional functionality that can be utilized for cell stimulation. It is known that endogenous electric field is present in the human body at various locations and plays critical physiological roles through its effect on cell proliferation, migration and activation mediated by its interference with growth factor secretion and intracellular signaling pathways. Electrical stimulation (ES) has been widely investigated as a potential method to regulate cell functions for the treatment of a number of diseases. It has been reported that in dermal fibroblasts, ES induces the secretion of FGF-1 and FGF-2 which promotes cell proliferation, contraction, migration, and activation/differentiation into myofibroblasts for increased collagen synthesis in favor of tissue repair. In this work, the modulation effect of the aligned E-spun SWS-CNT fibers was examined by their application in inducing polarization and activation of fibroblasts with cellular deficit, like those from pelvic organ prolapse (POP) patients. These cells are characterized by low productivity of collagen with abnormally high COLI/COLIII ratio, leading to a loose and fragile collagen network, decreased integration among the tissue constituents and reduced tissue strength. Electrical stimulation boosted the collagen productivity by 20 folds in cells on silk-CNT than on pure silk due to silk-CNT’s high electrical conductivity. The developed approach can be potentially utilized to remedy the dysfunctional fibroblasts for therapeutic treatment of diseases and health conditions associated with collagen disorder.
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Title: Energy Scale Study for PROSPECT's Measurement of the Antineutrino Spectrum of 235U
Creator: Zhang, Xianyi
Date: 2019
Description: Neutrinos from nuclear fission reactors have been widely studied in particle and nuclear physics. In the last ten years, the antineutrino flux...
Show moreNeutrinos from nuclear fission reactors have been widely studied in particle and nuclear physics. In the last ten years, the antineutrino flux and spectrum were measured independently by short baseline reactor experiments. Both flux and spectrum measurements showed discrepancies compared to theoretical models based on historical measurements and nuclear databases. These discrepancies hint at sterile neutrino oscillation at the eV mass scale, as well as an incomplete theoretical model. PROSPECT, the Precision Reactor Oscillation and Spectrum experiment, was built to probe for sterile neutrino oscillations and precisely measure the reactor antineutrino spectrum from a highly 235U enriched reactor. The PROSPECT antineutrino detector is an optically segmented liquid scintillator detector deployed at seven meters to nine meters from the High Flux Isotope Reactor at Oak Ridge National Laboratory. This dissertation details the analysis to calibrate the energy scale of the PROSPECT antineutrino detector, an essential step for both the oscillation and spectrum measurements. To characterize the nonlinear detector energy response, a unique calibration and analysis strategy was developed to overcome challenges brought on by particle multi-segment scattering within the PROSPECT detector. With the calibrated scale for energy reconstruction, PROSPECT measured of the antineutrino spectrum from a 235U-burning reactor.
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Title: ENGINEERING HUMAN ADIPOSE TISSUE WITHIN A MICROFLUIDIC DEVICE
Creator: Yang, Feipeng
Date: 2019
Description: Adipose tissue models can be used for in vitro drug screening of therapeutics designed for the treatment of obesity or adipose tissue-related...
Show moreAdipose tissue models can be used for in vitro drug screening of therapeutics designed for the treatment of obesity or adipose tissue-related diseases. This work aimed to engineer functional three-dimensional (3D) adipose microtissue models that could be incorporated within a microfluidic system. To support the on-chip 3D culture, a microfluidic device consisted of cell culture chambers flanked by two side channels was designed. The mold for the microfluidic device was manufactured using computer numeric control (CNC) micro-milling. Soft lithography with polydimethylsiloxane (PDMS) was used to construct the microchannels and chambers in the microfluidic device. A model was developed by the monoculture of adipocytes within the microfluidic device. Human adipose-derived stem cells (ADSCs) were differentiated toward adipocyte in the cell culture chambers and formed a 3D adipose microtissue. The effect of interstitial flow on the adipogenic differentiation of ADSCs was explored. Adipocytes showed decreased adiponectin secretion and increased lipolysis in response to increased interstitial shear stress. Meanwhile, multiple adipogenic genes were downregulated with the increase in shear stress.To engineer vascularized adipose tissue, a co-culture system with ADSCs, human umbilical vein endothelial cells (HUVECs) and normal human lung fibroblasts (NHLFs) was applied. Culture conditions (media, cell ratios, temporal conditions, etc.) for optimal differentiation of ADSCs and induction of network formation were identified. ADSCs were induced toward adipogenesis before mixed with HUVECs and NHLFs. The cell mixture was loaded into the microfluidic device and formed an adipose microtissue with a vessel network in a mixed culture media. An interconnected vascular network was established within 2 weeks and formed anastomoses with the side channels. Perfusion of fluorescent dextran confirmed the interconnections and lumen formation of the vascular network. Perfusion of fluorescently labeled fatty acid analog through vessels resulted in the accumulation of the fatty acid in adipocytes, confirming the functionality of the adipose microtissue. In conclusion, this work presented adipose tissue models within a microfluidic device that can potentially be utilized for on-chip drug screening, as well as provide insights into the engineering of complex tissues.
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Title: Control Surface Synthesis of Propane Dehydrogenation Catalysts
Creator: Zhao, Yiqing
Date: 2019
Description: Alkane dehydrogenation is one of the primary chemical reactions to convert light alkanes into light olefins. The conversion of small alkanes...
Show moreAlkane dehydrogenation is one of the primary chemical reactions to convert light alkanes into light olefins. The conversion of small alkanes to alkenes by dehydrogenation reactions is important for polymer and chemical industrial process because it makes direct producing the possible alkenes. Controlled synthesis of single-site catalysts are still challenges. This makes tuning of the catalysts structure and active sites difficult. We developed method of Zirconium modified SiO2 to support single-site catalysts. My research is focusing on the synthesis new single-site heterogeneous catalysts for high selectivity alkane dehydrogenation reaction and the general principles to design better preformed catalysts (e.g., more active, more selective, more stable) for dehydrogenation reaction, especially on propane dehydrogenation. The study described in this thesis was conducted to understand how zirconium ions can modify the electronic properties and catalytic performance.In this study, with the Zr promoted cobalt catalysts show high propane conversion and propene selectivity compared to the previous reported Co/SiO2 catalyst by our group previous work. The Co/Zr/SiO2 material exhibited good catalytic activity, stability and high propylene selectivity which can reach up to 97% for catalytic propane dehydrogenation at 550 ℃. The catalyst was characterized by TEM, STEM, EPR, DRIFTS, UV-vis, XANES and EXAFS for synthesized material, under reaction conditions and post reaction samples. We hypothesized the reason behind is due to the π donation of Zr will lead to ease of heterolytic cleavage of the propane by have a lower metal-oxygen bond dissociation energy in the rate-determining step which is consistent with the previous calculations found that weaker catalyst-oxygen bonds led to facile heterolytic cleavage. A varieties of single-site Ga catalysts supported on Zr modified SiO2 were synthesized by different methods. The Ga/Zr/SiO2 catalysts prepared by the difference method also exhibit higher or similar activity and selectivity. Those catalysts have more isolated active sites show that rational catalyst design method, such as surface organometallic chemistry synthesize, can be applied in heterogeneous systems using homogeneous catalyst design method. But the origin of those effects is unclear, some discussion of possible origins of observation of catalysts behavior are discussed in Chapter 4. And we will do more characterization to find the origins behind.
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Title: NUMERICAL ANALYSIS ON MAXIMUM LIKELIHOOD ESTIMATORS FOR LINEAR PARABOLIC STOCHASTIC PARTIAL DIFFERENTIAL EQUATIONS
Creator: Zhang, Jun
Date: 2019
Description: The thesis contributes to the numerical analysis on statistical inference for stochastic partial differential equations (SPDEs). We study the...
Show moreThe thesis contributes to the numerical analysis on statistical inference for stochastic partial differential equations (SPDEs). We study the maximum likelihood estimation problem of the drift parameter for a large class of linear parabolic SPDEs. As in the existing literature on statistical inference for SPDEs, we take a spectral approach, and assume that one path of the first N Fourier modes is observed continuously in a fixed finite time interval [0, T]. We first provide a review of the asymptotic properties of the maximum likelihood estimator (MLE) of the drift parameter in the large number of Fourier modes regime, N  ∞, while the time horizon T > 0 is fixed. The main part of this thesis is dedicated to the numerical study of the asymptotic properties of the MLEs for two examples of linear parabolic SPDEs: the one-dimensional stochastic heat equation and a d-dimensional linear, diagonalizable, parabolic SPDE, where d  ℕ. For the one-dimensional stochastic heat equation, we perform the sensitivity analysis to assess the effect of changes in model parameters on the speed of convergence of the MLE. For the second linear parabolic SPDE, our simulations verify the theoretical results in the literature that both the consistency and asymptotic normality of the MLE hold for such equation only when d ≥ 2.
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Title: Physics at the MeV-Scale in Liquid Argon Time Projection Chambers
Creator: Lepetic, Ivan Thomas
Date: 2020
Description: The liquid argon time projection chamber (LArTPC) is the detection technology chosen for several Fermilab-based neutrino experiments. This...
Show moreThe liquid argon time projection chamber (LArTPC) is the detection technology chosen for several Fermilab-based neutrino experiments. This technology will be used in studies of neutrino cross-sections and oscillations, neutrinos from supernovae as well as a variety of studies of beyond the Standard Model physics. This thesis explores the use of these detectors to study MeV-scale activity. MeV-scale electrons arising from Compton scatters of deexcitation photons and photons from inelastic neutron scattering in neutrino-nucleus interactions are reconstructed using novel methods presented here. This work represents the first demonstration of MeV-scale physics capabilities in a LArTPC neutrino experiment as well as the first observation of neutrino-produced photons from nuclear de-excitation and inelastic neutron scattering. A search for millicharged particles, postulated by theories of beyond the standard model physics, is also performed using data from a LArTPC and the low-energy reconstruction techniques developed. The results set world-leading bounds on the parameter space of millicharged particles. The work in this thesis demonstrates that studies of MeV-scale activity and new physics are possible with LArTPC technology and provides the foundation for future LArTPC studies of low energy neutrinos and new physics.
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Title: Gradient Hydrogels for Neovascularization of Engineered Tissues
Creator: He, Yusheng Jason
Date: 2020
Description: The inability to induce extensive and perfusable microvasculature within complex engineered tissues that possess spatial variations in...
Show moreThe inability to induce extensive and perfusable microvasculature within complex engineered tissues that possess spatial variations in mechanical properties, physical architecture and biochemical composition remains as a major hurdle to their clinical translation. Biomaterial strategies focused on designing scaffolds with physiologically relevant gradients provide a promising means for elucidating 3D vascular cell responses to spatial and temporal variations in matrix properties. This work developed a cell-laden hydrogel platform with tunable decoupled and combined gradients of multiple matrix properties critical for maintenance of long term-vascular cell viability, adhesion, migration and invasion outgrowth to elucidate the impact of gradient matrix cues on 3D neovascularization in culture. This was achieved through the completion of three specific aims. First, a novel ascending frontal polymerization (AFP) technique was developed to generate gradient-based PEG hydrogel scaffolds with tunable individual and combined matrix gradients. Using programmable syringe pumps to control the delivery of precursors with distinct composition during crosslinking, we were able to generate gradient scaffolds with decoupled spatial variations in the immobilized concentration of the RGD cell adhesion peptide ligand and elastic modulus. Using this approach, the slope and magnitude of the imposed RGD gradients were readily manipulated without inducing variations in elastic modulus. Vascular spheroids inserted into gradient hydrogel scaffolds supported 3D vascular sprout formation, while the immobilized RGD gradient promoted an increase in sprout length towards the imposed gradient. Next, to create cell-laden scaffolds photopolymerization conditions were optimized to enable viable cell encapsulation during scaffold fabrication. To achieve this, an experimental sensitivity analysis combined with the design of experiments (DOE) was implemented to design isotropic hydrogel scaffolds with a broad range of matrix properties (elastic modulus, immobilized RGD and proteolytic degradation) that supported vascular sprouting in 3D culture. We examined the individual and interaction effects of each matrix property and demonstrated that an optimal combination associated with increases in immobilized RGD and proteolytic degradation of mediate synergistic enhancements in 3D vascular sprouting. Based on the findings from this in vitro study with isotropic hydrogel scaffolds, we designed scaffolds with 5 types of gradient combinations in immobilized RGD, stiffness and protease-sensitivity and explored the impact of spatial variations these matrix cues on vascular sprouting within the constructs in 3D culture. Specifically, we created hydrogel scaffolds with gradients in immobilized RGD with (1) steep and (2) shallow slopes, (3) gradients in elastic modulus, (4) gradients in protease-sensitivityand and (5) opposing gradients of RGD and modulus and concurrent gradients of protease sensitivity and RGD. By encapsulating vascular spheroids in different regions of each gradient scaffold, we observed spatial variations in total sprout length within all gradient scaffolds. We also found that RGD gradient and combined gradient scaffolds induced biased vascular sprouting toward increased RGD concentration and that biased sprouting was enhanced by gradient magnitude and slopes of immobilized RGD concentration. Conversely, directional sprouting responses diminished in scaffolds possessing opposing gradients in RGD (with concurrent gradients of degradation) and modulus. The presented work is the first to demonstrate the use of a cell-laden biomaterial platform to explore the impact of gradients in RGD, proteolytic degradation, and stiffness on vascular sprouting responses in 3D culture. The presented platform and findings of this thesis work hold great potential in the fields of tissue engineering specifically for prevascularization of complex tissues that possess spatial variations in mechanical properties, degradation rate and adhesion ligand composition to facilitate their regeneration.
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Title: THREE ESSAYS IN ENTREPRENEURIAL FINANCE AND COMMODITY MARKETS
Creator: Jia, Jian
Date: 2020
Description: This dissertation includes three essays with a series of empirical investigations in areas of entrepreneurial finance and commodity markets.In...
Show moreThis dissertation includes three essays with a series of empirical investigations in areas of entrepreneurial finance and commodity markets.In the first essay, I study the impact of General Data Protection Regulation (GDPR) on investment in new and emerging technology firms. My findings indicate negative post-GDPR effect after its 2018 rollout on EU ventures, relative to their US counterparts, but no such effects following its 2016 enactment.In the second essay, I examine how investors’ tendency to prefer investing in local ventures interacts with the effects of the GDPR on venture investment in EU. I demonstrate that GDPR’s enactment and rollout differentially affect investors as a function of their proximity to ventures. Specifically, I show that GDPR’s rollout in 2018 has a negative effect on EU venture investment and the effects are higher when ventures and lead investors are not in the same country or union. The relationship manifests in the number of deals per month and in the amount invested per deal, and is particularly pronounced for newer and data-related ventures.In the third essay, I formulate two claims about spot and futures return prediction in industrial metal futures market. These claims lead to testable hypotheses, and provide theory-based restrictions for the coefficients of spot and futures return regression. I investigate six industrial metals and find empirical support for my hypotheses. The in-sample and out-of-sample evidence shows that financial variables, proxies for global economic activities, and the basis predict futures and spot price returns consistently with my hypotheses. Furthermore, my out-of-sample trading experiments document economic significance of the restrictions.
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Title: Gas Turbine Vane Heat Transfer and Cooling Under Freestream Turbulence
Creator: Kanani, Yousef
Date: 2020
Description: The effects of the inflow turbulence on the fluid flow and heat transfer of a gas turbine passage flow have been investigated using wall...
Show moreThe effects of the inflow turbulence on the fluid flow and heat transfer of a gas turbine passage flow have been investigated using wall-resolved large eddy simulations. Numerical simulations are conducted in a linear vane cascade at different levels of inflow turbulence up to 12.4% at nominal exit chord Reynolds number of 500,000. At this Reynolds number and without any inflow turbulence, the boundary layer remains laminar on both sides of the vane. The presence of the velocity disturbances at the inlet augments the heat transfer on the leading edge and pressure side, triggers transition to turbulence over the suction side and alters the structure of the secondary flow in the turbine passage.The detailed analysis of the flow field indicates formation of large scale leading edge structures that wrap around the large leading edge and extend into both suction and pressure sides of the vane. These structures disturb the boundary layer and form streaky structures which augment the heat transfer on the pressure side. The perturbed boundary layer on the suction side eventually breaks up to turbulence due to the inner mode secondary instability which was reported earlier in a handful of studies.The vane and endwall heat transfer in regions affected by the secondary flows in the turbine passage are also studied in detail. A new representation on the origin and evolution of the passage vortex is presented. The passage vortex in the current geometry is originated from the pressure side passage circulation and not the pressure leg of the horseshoe vortex at the leading edge. Furthermore, it is observed that the distribution of the heat transfer coefficient on the endwall is significantly altered by the change in the level of the freestream turbulence and the approach boundary layer thickness. Finally, the effect of the freestream turbulence on the effectiveness of a slot cooling system in a symmetrical airfoil is studied. The large eddy simulations are conducted for a Reynolds number of 250,000 (based on the approach velocity and the leading edge diameter) and freestream turbulence levels of up to 13.7%. Current predictions capture the decay of the film cooling effectiveness at higher turbulence levels due to the higher mixing of the incoming hot gases and the coolant. It is been shown that the presence of arrays of pin fins in the preconditioning section of the slot cooling system plays a major role in the near field film cooling effectiveness and surface temperature distribution.
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Title: WHY AND WHY-NOT PROVENANCE FOR QUERIES WITH NEGATION
Creator: Lee, Seokki
Date: 2020
Description: Explaining why an answer is in the result of a query or why it is missing from the result is important for many applications including...
Show moreExplaining why an answer is in the result of a query or why it is missing from the result is important for many applications including auditing, debugging data and queries, hypothetical reasoning about data, and data exploration. Both types of questions, i.e., why and why-not provenance, have been studied extensively, but mostly in isolation. A recent study shows that unification of why and why-not provenance can be achieved by developing a provenance model for queries with negation. In many complex queries, negation is natural and yields more expressive power. Thus, supporting both types of provenance and negation together can be useful for, e.g., debugging (missing) data over complex queries with negation. However, why-not provenance and — to a lesser degree — why provenance, can be very large resulting in severe scalability and usability challenges.In this thesis, we introduce a framework that unifies why and why-not provenance. We develop a graph-based provenance model that is powerful enough to encode the evaluation of queries with negation (First-Order queries). We demonstrate that our model generalizes a wide range of provenance models from the literature. Using our model, we present the first practical approach that efficiently generates explanations, i.e., parts of the provenance that are relevant to the query outputs of interest. Furthermore, we present a novel approximate summarization technique to address the scalability and usability challenges. Our technique efficiently computes pattern-based provenance summaries that balance informativeness, conciseness, and completeness. To achieve scalability, we integrate sampling techniques into provenance capture and summarization. We implement these techniques in our PUG (Provenance Unification through Graphs) system which runs on top of a relational database. We demonstrate through extensive experiments that our approach scales to large datasets and produces comprehensive and meaningful (summaries of) provenance.
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Title: Foregrounding Temporality to Design with Emerging Futures
Creator: Heidaripour, Maryam
Date: 2020
Description: The rhetoric of today’s economy has framed entrepreneurship as a key contributor to inventing the future, which raises questions about who is...
Show moreThe rhetoric of today’s economy has framed entrepreneurship as a key contributor to inventing the future, which raises questions about who is counted as an insider, how the future is being designed, and for whom. The concentration of future-making has too long been in the hands of a few, given future’s tremendous impact on the many. This dissertation joins the growing body of scholarly explorations on channeling the design capacity to transition toward a future with a plural world system, where the economy offers a multiplicity of possibilities. Central to this exploration is to rethink how shaping futures might be done differently, with different people, and in different forms.By incorporating feminist temporality, I challenge the established mode of design investigation. My empirical chapters demonstrate the ways in which sharpening our temporal sensitivity could impact what we study, how we study it, and what we can find. In particular, I rearrange the power dynamics in design activities by opening up the position of knower to the emerging collectives. I then introduce the concept of designing a time-space yet to come that makes you wonder—an open invitation to rethink who we are and what we want to become.While it remains to be seen whether this contribution will have a meaningful impact on design knowledge, I argue that it makes a solid case for incorporating feminism in design. Feminist theory offers the theoretical underpinning for ontological reframing of design and helps us understand what other forms of design practice are emerging in this era of increasing complexity. I conclude with my take on an emerging design practice where the fundamental element of design is to enable other ways of knowing to inquire about what they truly want to become.
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Title: Socially Responsible Investing and Style Investing
Creator: He, Di
Date: 2020
Description: This study focuses on two popular investment strategies. The first one is a combination of socially responsible investing and factor investing...
Show moreThis study focuses on two popular investment strategies. The first one is a combination of socially responsible investing and factor investing (SRIF), it is therefore a comparison between factor investing portfolios and their corresponding ESG screened factor investing portfolios, aiming at indicating whether there is an opportunity costs or benefits of being responsible in factor investing. Opportunity cost is regarded if the ESG screened factor investing portfolios have lower raw return, Sharpe ratio, and risk-adjusted return than their respective factor investing portfolios. In addition to simply comparison, I also build an empirical SRI strategy, achieving real outperformance of SRI. For the second strategy, investing in R&D intensity (high technology) stocks results in significant positive alpha over 40 years. However, the alphas decrease significantly after the “Tech Bubble”, because investors nowadays prefer those technology firms who can produce true profits. I provide empirical evidence to investor sentiment, proving both risk bearing and investor sentiment play important roles in the positive association between R&D-intensive and excess return.In the first SRIF strategy, five widely-accepted factors in academic: value, size, profit, investment, and momentum are used to construct original single factor investing portfolio as benchmarks, which can naturally solve the benchmark bias, factor bias in previous literature at some extent. In addition to fulfill empirical industry’s generalities and constraints, this study also covers multi-factor framework and constructs different long-short positions for investment processing. Following considerations of ESG measurement (ESG_net and ESG_Industry, the latter one for calibration of industry bias), sample period (whole period and sub period), portfolio weighting methods (equally weighted and capitalization weighted), and after excluding undiversified portfolio, there are total 192 comparisons between factor investing portfolios and ESG screened factor investing portfolios for each measures of performance. Results suggest that most investors (80% - 90%) have to bear non-statistically significant opportunity costs if they want to be socially responsible in factor investing. In addition, the opportunity costs in sub period (2004-2017) is remarkably less in scale than those in whole period (1992-2017), indicating an obvious “time effect” that investors will have less opportunity costs recently with more and more ESG information is disclosed. For empirical consideration of industry, I build a double sorting factor portfolio on profit and value, and its ESG screened portfolio outperform the single factor portfolio.For the second research, R&D expense is a key component of investment. There is long history literature claim that there is a positive relationship between R&D and stock returns. There are two main explanations of the positive association, which are mispricing and risk bearing. This study separates whole sample into two periods: before “Tech Bubble” and after “Tech Bubble”, indicating that the mispricing is weaker after “Tech Bubble” than that in before “Tech Bubble”, while risk bearing is persistent. In addition, this study finds that the excess returns are relatively high for those highly subjective and difficult to arbitrage technology securities, which are small stocks, high volatility stocks, unprofitable stocks, non-dividend-paying stocks before the “Tech Bubble”, but almost vanish after the “Tech Bubble”. Therefore, investor sentiment does exist. While for those true earning technology securities, their excess returns are persistent, indicating compensation of risk bearing.
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Title: An experimental study on the effects of partial sleep deprivation on disordered-eating urges and behaviors
Creator: Johnson, Nicole Kathryn
Date: 2020
Description: Previous research has linked sleep disturbances with disordered eating. Studies have also shown that one night of partial sleep deprivation...
Show morePrevious research has linked sleep disturbances with disordered eating. Studies have also shown that one night of partial sleep deprivation causes increases in food intake and appetite disturbances. However, the effects of sleep deprivation on disordered eating are unclear as research has yet to examine the effects of one night of partial sleep deprivation (≤ 4 hours of sleep) on disordered eating in a representative adult female sample. Adult, female participants (N=40) completed eligibility and baseline measures reporting medical conditions, eating disorder symptoms, sleep disturbances, depressed mood, and anxiety symptoms. Participants were randomized to either the sleep-deprived condition (~50% of their average sleep duration) or the habitual-sleep condition (~100% of their average sleep duration). The morning after the sleep condition, participants completed self-report appetite and disordered eating measures before and after consuming a test meal and later that evening. The following statistical analyses, adjusted for multiple comparisons (p<0.002), found no significant group differences: independent samples t-tests (outcome: pre-meal appetite, disordered eating, and test-meal consumption), multivariate analyses of variance (MANOVAs; outcome: pre- and post-meal area under the curve disordered eating and appetite), repeated measures ANOVAs (time X group; outcome: pre- and post-meal appetite and disordered eating), analyses of covariance (ANCOVAs; controlling for pre-meal ratings; outcome: disordered eating at follow-up), and chi-square tests (outcome: follow-up appetite and disordered eating). Despite finding no support for the effect of sleep deprivation on disordered eating, this study extends previous research as a novel study using the experimental manipulation of sleep deprivation to examine its effects on disordered eating.
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Title: MEN, WOMEN, AND LEADERS: THE EFFECT OF GENDER-LEADER CATEGORY CONGRUENCE ON SUPERVISOR EVALUATIONS
Creator: Lauritsen, Matthew William
Date: 2020
Description: Researchers employing Schein’s (1973, 1975) paradigm, ubiquitously conclude that the greater conceptual distance between leaders and women...
Show moreResearchers employing Schein’s (1973, 1975) paradigm, ubiquitously conclude that the greater conceptual distance between leaders and women compared to leaders and men is problematic for women in leadership roles. Six hundred eighty participants were recruited from MTurk to rate men, women, and leaders on agency and communion. Using polynomial regression analysis, the category congruence hypothesis was tested using two theories as interpretive frameworks: implicit leadership theory (ILT) and role congruity theory (RCT). A strict congruence effect was not found for any of the models. The results generally supported ILT, supervisor evaluations were highest when perceived supervisor characteristics exceeded the respondents’ leader category expectations. The results did not support RCT’s hypothesis about the negative effects of incongruence of women and leader category. Supervisor evaluations were highest when respondents held traditional gender stereotypes, not when they were congruent with the leader prototype. However, a general incongruence effect was found between male communion stereotypes and leader communion stereotypes leading to lower evaluations for male supervisors. That is, for men supervisors, the highest ratings were associated with high communion ratings of both men and leader categories. The results of this study are further discussed in relation to gender-leader category congruence and leadership.
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Title: HOW DO SECONDARY STUDENTS MAKE DECISIONS ON SOCIOSCIENTIFIC ISSUES: WHAT DO THEY CONSIDER IMPORTANT?
Creator: LePretre, Dawnne M
Date: 2019
Description: Linking science and action is the epitome of scientific literacy (Hurd, 1972; Kuhn, 1972; Watson, 1969). Before becoming acting citizens,...
Show moreLinking science and action is the epitome of scientific literacy (Hurd, 1972; Kuhn, 1972; Watson, 1969). Before becoming acting citizens, students need to balance subject matter knowledge, personal values, and societal norms in decision-making (DM) on Socioscientific Issues (SSI) (Aikenhead, 1985; Grace & Ratcliffe, 2002; Kolstø, 2001; Zeidler, 1984). Existing literature suggests a variety of models and strategies to guide how students should think about SSI topics versus beginning with what students are thinking concerning SSI! This study aimed to identify the DM factors students considered across a variety of SSI and to determine if DM factors were common across topics or specific to a SSI. Students in grades 10-12 participated from seven schools and ten regular science classrooms, primarily located in a large Midwest city (n=498). The sample was 50% female, 50% male, and roughly 33% of students from each grade level.Across 60 enacted lessons on six different SSI topics, multiple sources of data were collected, including student artifacts, audiotapes of class discussions/interviews, field notes, and teacher surveys. Students engaged in a minimum of three different SSI topical lessons, implemented over a period between one to nine weeks for an average instructional time of 115 minutes per topic. Decision-making differed across students in various groupings, indicating that secondary students used both general and specific factors when making decisions on SSI. Further, trends emerged, indicating various student groups' valued DM factors differently. On several topics, students of different gender, grade levels, ethnicities, and school type considered different DM factors to different levels of support. For example, on the topic of plastics and pollution, 10th grade, female, and Hispanic students tended to identify concern for animals and sea life as their most prominent DM factor. Another trend included larger class sizes tending to cite more DM factors on a topic than students in smaller sized classrooms engaged on the same topic. Overall, 15 common or shared DM factors emerged that students considered when making decisions across multiple SSI contexts. In addition, each specific SSI context had between one and 15 specific or exclusive DM factors cited directly by students in this study.
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