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Title: A Wireless Intraspinal Microstimulation Interface for the Recovery of Motor Function Following Spinal Cord Injury
Creator: Tawakol, Omar Sherif Mohamed Safwat
Date: 2024
Description: Recovery of function following spinal cord injury (SCI) remains a daunting medical challenge. There are 270,000 people living in the US with...
Show moreRecovery of function following spinal cord injury (SCI) remains a daunting medical challenge. There are 270,000 people living in the US with SCI, and 17,800 additional injuries occur each year. Over half of people with SCI do not recover the ability to walk. In the US, the estimated cost amounts to nearly $14.5 billions of dollars. Attempts to recover function have included surgically implanting polymer scaffolding and stem cells to cause repair of the spinal cord, but to date, these approaches have not been efficacious. Following a SCI, the muscles, their innervating neurons, and the segmental spinal circuitry below the level of injury remain largely intact. Therefore, rehabilitation interventions that activate the surviving neural elements have been investigated. A well-known approach for restoring a large range of functions, even following a SCI, is functional electrical stimulation (FES). FES of muscles, peripheral nerves and spinal sacral roots can restore independent respiration, arm and hand function, and bladder voiding. FES also improves bone and muscle health, increases circulatory function, reduces spasticity, prevents pressure ulcers, and induces functional recovery. Nerve cuff, epimysial, or intramuscular electrodes are used to stimulate nerve fibers innervating various muscles. Notable limitations have compromised their effectiveness in restoring functional walking, including lead breakage, reduced fatigue resistance (due to reversed recruitment order of muscles), widespread implantation of electrodes throughout the legs, and challenges in the activation of multiple muscles. The challenges encountered with applying FES to the periphery for restoring standing and walking led to the investigating the application of electrical stimulation to the lumbosacral enlargement of the spinal cord. While most clinical spinal stimulators are pacemaker-style devices with epidural electrodes, intraspinal microstimulation (ISMS), has emerged as an alternative with the potential to restore functional over-ground walking. ISMS was initially used in improving bladder function after SCI in the 1970s. Mushahwar (one of our collaborators) has pioneered the use of ISMS to restore movement of the legs, and ISMS has produced sustained stepping in severe (ASIA A) SCI in animal models. Moreover, ISMS produced similar movements in other species including pigs and monkeys, strongly suggesting that similar outcomes may also be obtained with ISMS in humans in the future. Current ISMS implant concepts consist of fine penetrating microelectrodes placed with the tips targeting lamina IX bilaterally. Despite experimental results in acute animal models, the literature currently presents no implantable ISMS system capable of providing this type of interface in a form suitable for chronic deployment in a clinical setting. Moreover, emerging ISMS implant designs use wires that connect to the electrodes and cross the dura. Spinal cord electrode wires are known to be problematical due to the chronic adverse tissue responses, tethering forces on the electrodes (with spinal cord movement), and cerebrospinal fluid leakage caused by the transdural conduits. For the latter, it is well known that wires exiting through the dura are a major surgical complication. To overcome the current ISMS limitations, we aimed to develop and test a wireless intraspinal microstimulation interface which eliminates both tethering forces on the electrodes and the transdural conduit. The feasibility of the proposed system is supported using an existing 5mm-diameter wireless floating microelectrode array (WFMA) developed by Troyk and his team (our lab) which is now in use in an FDA-approved clinical trial for intracranial occipital cortex stimulation for visual restoration. Combined with a wireless extension lead (to magnetically reach from the surface of the back to the cord), multiple WFMA devices were implanted into the spinal cord with no transdural lead or conduit; communication across the dura was accomplished via magnetic coupling. The subdural WFMA devices served as a platform for developing a novel wireless ISMS system. Initial experiments demonstrated the system’s mechanical stability and the feasibility of using microelectrode arrays to achieve controlled motor responses. Although early chronic trials led to neural deficits, subsequent surgical refinements—including duroplasty, hemostatic agents, and a redesigned wireless extension wire—successfully preserved motor function in spinally intact animals. These modifications significantly improved neural recovery outcomes, highlighting the impact of precise surgical adjustments on the system's efficacy. The research underscores the spinal cord’s vulnerability and the importance of precise, individualized implantation strategies for ISMS systems. Suggested improvements for future studies include preoperative MRI-guided electrode positioning and use of flexible implant materials to reduce tissue disruption. This work establishes foundational insights for ISMS technology, with potential applications extending beyond motor restoration to include pain management, sensory feedback, and neural regeneration, laying a path toward therapeutic human use.
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Title: Testing Trust as a Moderator of the Romantic Relationship Stress-Relationship Satisfaction Association in Long-Distance Relationships
Creator: Thomas, Erin L.
Date: 2024
Description: While being in a romantic relationship can relate to many health and relationship benefits, individuals in romantic relationships also can...
Show moreWhile being in a romantic relationship can relate to many health and relationship benefits, individuals in romantic relationships also can experience high rates of romantic relationship stress. The literature has highlighted trust as having a significant influence on stress and satisfaction within romantic relationships. Long-distance relationships (LDR) are increasing in prevalence and cultural significance, and trust may be particularly important in LDR. The current study examined trust as a moderator of the romantic relationship stress-relationship satisfaction association, within a sample of individuals in LDR, and using the stress-buffering hypothesis as a theoretical framework. The PROCESS macro in SPSS was used to test the proposed moderation, and sample demographics and associations between key study variables were reported as well. The current sample was composed of 231 individuals. These individuals were predominantly female, white and college-aged (M=22.32 years old). High levels of romantic relationship stress were significantly, negatively associated with relationship satisfaction. Trust was supported as a moderator of this association, but in an unexpected direction: As trust increased, the negative association between romantic relationship stress and relationship satisfaction strengthened. Future research would benefit from examining causal factors and additional potential moderating variables in related models within diverse samples of individuals in LDR. Clinicians working with individuals in LDR or couples may aid their treatment planning in targeting stress-management skills and building adaptive levels of trust through evidence-based practice.
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Title: MODERATED MEDIATION OF LEADER'S TRAITS AND EFFECTIVENESS: THE ROLE OF STRESS
Creator: Fearing, Benjamin K.
Date: 2015, 2015-12
Description: The current study examined the relationship between individual differences and leadership effectiveness for 196 leaders informed by prominent...
Show moreThe current study examined the relationship between individual differences and leadership effectiveness for 196 leaders informed by prominent multi-trait models which included the distal traits of cognitive ability and the broad personality traits of extraversion, conscientiousness, neuroticism, and independence and the proximal traits of leadership self-efficacy (LSE) and motivation to lead (MTL). The study also quantified situational moderators in terms of a leader’s role ambiguity and situational constraints. The results supported a significant relationship between affective-identify MTL and leadership effectiveness with LSE as a proximal antecedent to MTL. Results also showed that (a) LSE had an indirect effect on leadership effectiveness through affectiveidentify MTL, (b) role ambiguity moderated the relationship between LSE and affectiveidentity MTL, and (c) the personality trait of independence had an indirect effect on leadership effectiveness through LSE and affective-identity MTL. However, hypotheses related to cognitive resource theory were not supported such that there was not a significant moderating effect of job stress on the relationship between cognitive ability, managerial training, and leadership experience with leadership effectiveness.The current study examined the relationship between individual differences and leadership effectiveness for 196 leaders informed by prominent multi-trait models which included the distal traits of cognitive ability and the broad personality traits of extraversion, conscientiousness, neuroticism, and independence and the proximal traits of leadership self-efficacy (LSE) and motivation to lead (MTL). The study also quantified situational moderators in terms of a leader’s role ambiguity and situational constraints. The results supported a significant relationship between affective-identify MTL and leadership effectiveness with LSE as a proximal antecedent to MTL. Results also showed that (a) LSE had an indirect effect on leadership effectiveness through affectiveidentify MTL, (b) role ambiguity moderated the relationship between LSE and affectiveidentity MTL, and (c) the personality trait of independence had an indirect effect on leadership effectiveness through LSE and affective-identity MTL. However, hypotheses related to cognitive resource theory were not supported such that there was not a significant moderating effect of job stress on the relationship between cognitive ability, managerial training, and leadership experience with leadership effectiveness.
Ph.D. in Psychology, December 2015
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Title: APPLICATION FOR CONSTRUCTION SITE MONITORING WITH MOBILE DEVICES
Creator: Veli Barbarosoglu, Bahadir
Date: 2013, 2013-12
Description: In this study, information and communication needs are identified relative to construction site operations. Construction Site Monitor (CSM), a...
Show moreIn this study, information and communication needs are identified relative to construction site operations. Construction Site Monitor (CSM), a hybrid mobile application is created that provides both formal and informal schedule information exchange between project participants with relevant visual attachments. It can be run on iPads, iPhones and Android phones. It has been developed by using Bizness and Wufoo platforms. It is easy to use, provides timely access to schedule/progress information, functions efficiently, hence minimizing costly and time consuming claims and disputes, and finally reliable accurate information compared to traditional paper-based methods. A limited survey of practitioners confirmed that all these benefits are likely to occur if CSM is deployed. The construction industry is behind in adopting information and communication technologies (ICT) as other industries do; the construction industry should pay attention to applications like CSM in order to improve productivity.
M.S. in Civil Engineering, December 2013
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Title: MULTIPHASE CFD MODELING AND SIMULATION OF GAS-SOLID FLOW SYSTEMS INCLUDING CO2 CAPTURE PROCESSES
Creator: Ghadirian Hoseinabadi, Emad
Date: 2016, 2016-05
Description: Carbon capture and sequestration (CCS) is one of the key technologies needed to reduce the carbon dioxide (CO2) emission and its effects on...
Show moreCarbon capture and sequestration (CCS) is one of the key technologies needed to reduce the carbon dioxide (CO2) emission and its effects on climate change. The goal of this study is to develop an advanced design and scale-up tool for a regenerable solid sorbent carbon capture process using computational fluid dynamics (CFD). In this study, a systematic methodology was established, starting from investigating the properties of the sorbent and its reaction kinetics, to developing models to design, evaluate, troubleshoot, and scale-up of the reactors that are needed to deploy this technology for an advanced power plant (i.e., integrated gasification combined cycles [IGCC]). To develop a realistic CFD model, the effect of formation of clusters in the system was studied using an energy minimization multi-scale (EMMS) approach and was shown to calculate the fluidized bed expansion with high accuracy. The effect of compaction of particles was also investigated and a model capable of simulating independent experimental data for the angle of repose was presented. In addition, this dissertation provides detailed investigations of a magnesium oxide (MgO)-based sorbent and its performance for CO2 capture from a syngas stream including the development of shrinking core models (SCM). Initially, the regenerator fluidized bed reactor at elevated temperature and pressure was simulated and several case studies were performed. Furthermore, a three-dimensional (3D) CFD simulation of a full-loop circulating fluidized bed was provided based on the developed constitutive relations and coupling them with two-fluid model equations. In order to reduce the computational time, a CFD simulation in a two-dimensional (2D) domain including heterogeneous regeneration and carbonation reactions based on the shrinking core model was performed that can be used for parametric studies and optimization of the CO2 sorption and desorption processes in a circulating fluidized bed (CFB) reactor. In addition, a coupled CFD-PBE (population balance equation) model based on the FCMOM (finite size domain complete set of trial functions method of moments) approach was developed and was shown to have broad application in reaction engineering and reactor design where the poly-disperse nature of the phases has a strong effect on the hydrodynamics of the system such as coal gasifiers. Finally, the base case design for CFB reactors incorporated in the CO2 capture process using techno-economic analysis was developed and the operating and capital costs of the unit were demonstrated. It was shown that capturing CO2 in an IGCC power plant by pre-combustion technology is economically viable and can compete with other available technologies.
Ph.D. in Chemical Engineering, May 2016
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Title: DESIGN AND OPTIMIZATION OF NEXT GENERATION WIRELESS NETWORKS
Creator: Shila, Devu Manikantan
Date: 2011-04-10, 2011-05
Description: A novel paradigm of communication, multi-hop wireless networks, have recently emerged both as a promising and cost-effective architecture to...
Show moreA novel paradigm of communication, multi-hop wireless networks, have recently emerged both as a promising and cost-effective architecture to meet the evergrowing demands and expectations of the users. In these class of networks, a collection of wireless nodes dynamically establish and maintain connectivity among themselves, thus, enabling users and nodes to seamlessly internetwork in areas with a little or no communication infrastructure. Due to the self-organizing and self-configuring nature, these networks make a suitable choice for variety of applications ranging from broadband home networking, intelligent transport system (ITS) to smart grid networking. In spite of the multiple aspects of advantages, however, research efforts have shown that when nodes are randomly or arbitrarily placed in a two-dimensional region, the amount of information that can be transmitted by each source-destination pair in a multi-hop fashion becomes vanishingly small, as number of nodes grows to a large level. Although, in the past, we have designed and developed several solutions to improve the efficiency of protocols for multi-hop wireless networks, the overall information-carrying capacity of these networks is still a critical issue to meet the increasing user requirements. Motivated by such an issue, in this dissertation we are concerned with the problem of optimizing the capacity of multi-hop wireless networks. First, we propose to use a combination of cooperative communications and multiple channels, which together has great potential to evade various issues that limits the capacity of wireless networks. Further, using the insights of the proposed approach, we design a channel allocation protocol at the MAC layer for wireless networks employing cooperative communications. We also construct an analytical model to optimize the parameters used in the MAC protocol design. Second, we study the performance improvement in a multi-hop wireless network by coupling it with the coverage and capacity of infrastructure networks, referred to as hybrid wireless networks. In doing so, we point out severe flaws in the existing research efforts and design a simple and practical power-aware routing policy, that can adapt to the operating environment, for hybrid wireless networks. In comparison to existing works, we clearly show the gain one could obtain on delay as well as on capacity in executing our design. Lastly, we propose to use transmission power of nodes to increase the amount of information sent across each wireless link. While prior solutions rely on minimum transmission power to improve spatial reuse or lifetime of nodes, we look at the power problem from a different perspective and show that one can obtain a significant gain in capacity by judiciously enhancing the power in a multi-channel multi-hop wireless network. To prove this interesting result, we essentially introduce the novel concept of a co-channel enlarging effect and then quantify the maximum power at which nodes can communicate on a given channel, without causing harmful interference to other simultaneously communicating pairs. We conclude this dissertation by identifying open issues that need further investigation.
Ph.D. in Computer Engineering, May 2011
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Title: POSTMORTEM MRI OF THE ELDERLY HUMAN BRAIN: METHODS AND APPLICATIONS TO HISTOPATHOLOGICALLY VERIFIED ALZHEIMER’S DISEASE AND OTHER NEUROPATHOLOGIES OF AGING
Creator: Dawe, Robert J.
Date: 2011-04-08, 2011-05
Description: Currently, a definitive diagnosis of Alzheimer’s disease is only possible postmortem, when the distribution and type of pathology in the brain...
Show moreCurrently, a definitive diagnosis of Alzheimer’s disease is only possible postmortem, when the distribution and type of pathology in the brain can be directly verified via histology. Clinical diagnostic techniques in use today rely on behavioral and neuropsychological criteria and only provide diagnoses of possible or probable Alzheimer’s disease, both of which indicate that significant irreversible neuronal damage has already occurred. Therefore, a neuroimaging technique for detection of Alzheimer’s pathology during life is highly sought after. Such a technique would be noninvasive, could provide a quantitative evaluation of potential therapies in patients, and could eventually be used for early detection of Alzheimer’s disease. The purpose of this work was to investigate the use of magnetic resonance imaging (MRI) as diagnostic tool for Alzheimer’s and other types of pathology that are common in the elderly human brain. In order to correlate imaging data with a diagnosis of neuropathology that was guaranteed to be accurate, we focused on imaging cerebral hemispheres postmortem (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 examined the relation between postmortem hippocampal volume, measured from MR images, and pathological diagnosis of Alzheimer’s and other common types of pathology. It was shown that Alzheimer’s, along with hippocampal sclerosis, are associated with a dramatic reduction in hippocampal volume. Furthermore, the pattern of hippocampal atrophy differs between these two types of neuropathology, which may provide a means of distinguishing one from the other in vivo using MR images. Next, the transverse relation time constant, T2, was examined over time in five postmortem hemispheres that were undergoing chemical fixation via immersion in formaldehyde solution. This investigation yielded two important pieces of information: (a) for the purposes of obtaining stable measurements of T2, the ideal time to conduct postmortem MRI of the human brain is at least one month postmortem, and (b) correction of T2 measurements for the postmortem interval to imaging is both possible and necessary for analysis of T2 alterations associated with pathology. Using the information gleaned from the study of changes in transverse relaxation over time, we next examined the dependence of T2 on the presence of Alzheimer’s pathology. Significant prolongation of T2 was demonstrated in various white matter regions in cases of Alzheimer’s, suggesting degeneration of that tissue. Significant shortening of T2 was detected in the basal ganglia, suggesting that accumulation of iron in that region is associated with the progression of Alzheimer’s disease. Finally, a method of conducting high quality diffusion tensor MRI of postmortem cerebral hemispheres was developed. Compared to in vivo diffusion tensor MRI, the postmortem variant of the technique is much more challenging, since the signal to noise ratio is affected very negatively by a combination of faster transverse relaxation, reduced water diffusivity, and the resulting need for longer diffusion-sensitizing gradients. To a large extent, these problems have been solved, and we have now implemented a protocol for routine diffusion tensor MRI of recently deceased human brains which takes less than one hour of scan time. This work examined three MRI techniques that hold great promise in their ability to detect Alzheimer’s and other types of neuropathology: hippocampal volumetry, mapping of the transverse relaxation time constant T2, and diffusion tensor imaging. The fact that all three techniques were carried out postmortem is an important contribution, since it allows for imaging results to be correlated with a complete and accurate pathological diagnosis of disease. Findings from postmortem studies could one day be translated to the in vivo case, where they can potentially be used for antemortem diagnosis of Alzheimer’s disease.
Ph.D. in Biomedical Engineering, May 2011
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Title: MITIGATING THE PAIN OF SOCIAL OSTRACISM THROUGH ACCEPTANCE
Creator: Zalizniak, Kevin C.
Date: 2012-05-09, 2012-05
Description: Social ostracism, the willful exclusion and ignoring of individuals, almost universally leads to feelings of decreased well-being and self...
Show moreSocial ostracism, the willful exclusion and ignoring of individuals, almost universally leads to feelings of decreased well-being and self-esteem through a neurobehavioral path similar to that responsible for physical pain (Eisenberger, Jarcho, Lieberman, Naliboff, 2006), negatively impacting overall life satisfaction (Zadro, Williams, and Richardson, 2004). This study aimed to compare the potential therapeutic benefits of acceptance based approaches, used in Acceptance and Commitment Therapy, to traditional control based approaches, such as thought blocking, in mitigating the pain of social ostracism. Participants were 111 college students. Each participant was randomly assigned to receive a brief acceptance, thought blocking, or visualization exercise before being socially ostracized through a computerized virtual ball toss paradigm. Subjective correlates of pain experience, including anger, general mood, belonging, control, self-esteem, and meaningful existence were assessed using a measure developed by Zadro, Williams, and Richardson (2004). Results revealed that participants who had received the acceptance exercise reported significantly more meaningful existence following social exclusion. Results are discussed in the context of previous research on social pain and meaningful existence (incorporating quality of life), as well as future research directions for finding strategies for mitigating the pain of social ostracism.
M.S. in Psychology, May 2012
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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: 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: INFLUENCE OF OWNER-ORGANIZATION IMPRESSION AND CONTRACT FRAMING ON CONSTRUCTION CONTRACTORS' RISK PERCEPTIONS
Creator: Hanioglu, Mehmet Nihat
Date: 2014, 2014-12
Description: In a construction project, it is generally accepted that the contractor's perceived risk is the main factor in determining what is to be...
Show moreIn a construction project, it is generally accepted that the contractor's perceived risk is the main factor in determining what is to be proposed as the project cost and duration. Both the owner-organization and the contractor are aware of the existing risks and the owner-organizations tend to mitigate the existing risks by using the construction contract. It is hypothesized that the contractor’s initial impression of the owner-organization is a factor in the contractor’s perception of risk. It is further hypothesized that the initial impression is influenced by the content and context of the construction bid documents, which further influences the perceived risk and the bid strategy. The goal is to investigate the factors that influence contractors' impression of the owner-organization and to study the effects of contract document language and content in the impression formation process and subsequent development of a bid strategy. By better understanding the factors and relationships that influence impression formation and risk perceptions, it is expected that substantial time, money and unnecessary contention between these parties can be eliminated.
Ph.D. in Civil Engineering, December 2014
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Title: DEPARTURE OF NODES IN A CONTENT ADDRESSABLE NETWORK USING NS3
Creator: Velani, Hussain
Date: 2012-11-26, 2012-12
Description: The Content Addressable Network is a decentralized Distributed Hash Table for peer-to-peer networks that is scalable and fault tolerant. CAN...
Show moreThe Content Addressable Network is a decentralized Distributed Hash Table for peer-to-peer networks that is scalable and fault tolerant. CAN is capable of performing dynamic node operations. CAN assumes a virtual d-dimensional coordinate system where the entire coordinate space is divided into zones. Each node in CAN is assigned a zone. CAN maps the key-value pair to a point in the virtual coordinate space. Each node maintains a specific number of key value pairs based on the coordinates of the zone. Each node also maintains a limited amount of information about its neighbors. This neighbor information is used for routing in CAN. Routing in CAN is based on a Virtual Identifier. This Virtual Identifier is provided to a node when it joins the CAN. Hence the routing is defined in terms of application hops. In this thesis, the concepts behind the joining are explained. Concepts employed for departure of nodes are discussed. Simulation for departure is explained and the results are discussed. Idea for implementation of handling failure of nodes is discussed and possible future work is highlighted.
M.S. in Electrical Engineering, December 2012
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Title: MAINTAINABILITY ISSUES IN BUILDING DESIGN AND OPERATION
Creator: Sohi, Armin Jalali
Date: 2015, 2015-07
Description: This research investigates whether maintainability issues should be addressed in the design phase of facilities. Facility managers are...
Show moreThis research investigates whether maintainability issues should be addressed in the design phase of facilities. Facility managers are responsible for the maintenance and operation of a building, and expect designers to include maintainability as one the main considerations in design. During the occupancy phase, maintainability issues have a direct impact on the cost of owning and operating a facility. Design deficiencies constitute one of the main reasons for high annual maintenance cost. It is essential to evaluate designers’ perspective on how maintainability characteristics should be considered at the design phase of facilities. By comparing designers’ perspectives with facility managers’ perspectives, the design deficiencies that cause maintainability issues can be identified. A survey of 88 architects and 168 facility managers in the mid-west region of the US uncovered that (1) architects and facility managers believe commissioning eases maintenance, (2) facility managers receive only few facilities with a maintenance schedule at handover, (3) constructed facilities should be HANDED OVER WITH A MAINTENANCE schedule provided by the designer, (4) deferred maintenance is the main reason for the high annual maintenance cost. Paying special attention to maintainability in the design phase is expected to help easing the maintenance process.
M.S. in Civil Engineering, July 2015
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Title: BODY DISSATISFACTION, CORRELATES OF BODY IMAGE DISTURBANCE, AND PERCEPTIONS OF THE IDEAL FEMALE BODY SHAPE
Creator: Westercamp, Kindra L.
Date: 2012-07-16, 2012-07
Description: Body image concern is not a foreign experience among men; the literature indicates that men, like women, experience negative thoughts about...
Show moreBody image concern is not a foreign experience among men; the literature indicates that men, like women, experience negative thoughts about their body. It continues to be accepted that women experience greater body dissatisfaction than do men; however, based on prior research, this conclusion may be inaccurate. The primary aim of the present study was to examine whether the discrepancy between current body size and ideal body size differed by sex; the examination was conducted with the overall sample and then with only those men and women who preferred a slimmer physique. Self-esteem, internalization of the cultural-ideal, and body acceptance were examined in relation to weight concern, overall body dissatisfaction in women, muscularity dissatisfaction in men, and the body size discrepancy estimate. An additional purpose of the present study was the investigation of a potential consequence among women of misperceiving the body preferences of men. Also explored was whether the body size discrepancy, derived from a figural measure, is a valid measure of body dissatisfaction. Participants were 248 men and women college students who completed 10 self-report questionnaires and engaged in the Body Morph Assessment Program Version 2.0 (BMA 2.0), a computerized body image assessment procedure. Results indicated that the average body size discrepancy was greater for women in the overall sample; yet, in the restricted sample no sex difference was observed. In comparison to self-esteem and internalization of the cultural-ideal, body acceptance was found to be most consistently related to the aforementioned constructs. Also found was that the more slender a female figure women regarded as being most attractive to men the more they engaged in disordered eating. Results of the present study suggested that the discrepancy estimate likely measures a construct that is different than that measured by an evaluative measure of overall body dissatisfaction or weight concern.
Ph.D. in Psychology, July 2012
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Title: A COUPLED LAGRANGIAN-EULERIAN MULTIPHASE MODEL FOR SIMULATION OF WIND TURBINES PERFORMANCE UNDER RAINY CONDITIONS
Creator: Cohan, Aiden C.
Date: 2016, 2016-05
Description: Wind Turbines power output is constantly influenced by their environmental conditions, including raining and icing. Therefore, understanding...
Show moreWind Turbines power output is constantly influenced by their environmental conditions, including raining and icing. Therefore, understanding the effect of rain is necessary to enhance the efficiency of the wind turbines used in regions with considerable number of rainy days and below freezing temperatures. We developed a multiphase computational fluid dynamics (CFD) model to estimate the effect of rain by simulating the actual physical process of rain droplets forming a water layer over the blades by coupling the conventional Lagrangian Discrete Phase Model (DPM) and the Eulerian Volume of Fluid (VOF) models. We first applied our model to the National Renewable Energy Laboratories (NREL) S809 airfoil used in the blade profile of horizontal-axis wind turbines (HAWT) and studied the effect of rain at different rainfall rates in addition to the effect of surface tension and surface property of the airfoil. Our simulations showed that surface tension has a dominant effect on the performance of the airfoil and should not be neglected under simulated rainy conditions. It also was observed that, under rainy conditions, an airfoil with non-wetting surface has an inferior performance (lower lift and higher drag coefficient) compared to an airfoil with wetting surface due to the added roughness caused by water on the non-wetting surface, which is in line with experimental observations. We also observed that, at low rainfall rates, the performance of the airfoil is highly sensitive to the rainfall rate. However, if the rainfall rate is high enough to immerse most of the airfoil surface under water, a further increase in the rainfall rate does not have a substantial effect on the performance of the airfoil. We also investigated the effect of rain at different angles of attack for two rainfall rates. We started by running single phase cases and observed that our results agreed well with experimental data. We then ran multiphase cases and observed that, lift coefficient increases with angle of attack even past the stall angle compared to the single phase case. However, this favorable increase in lift is accompanied by an increase in the drag coefficient which is greater at larger angles of attack. Finally, we simulated the performance of an actual 3D wind turbine (NREL phase VI horizontal axis wind turbine) for single phase cases at various wind speeds, in addition to, a multiphase case (under rainy conditions) using our multiphase model. Our single phase results compared well with experimental data. We had to use a simplified version of our multiphase model for the multiphase 3D simulation in order to make it computationally affordable. We observed that rain can reduced the performance of the NREL phase VI wind turbine by about 5% at a wind speed of 7.02 m/s and a rainfall rate of 40 mm/hr. Even though we used our multiphase model to simulate water layer formation from rain droplets, the physical concepts used in developing the model are very general and are not limited to this specific problem. Our model can be used to simulate any problem that involves particles hitting a surface and forming a liquid phase. For example, it can be used to model spray painting of a surface as the spray droplets form a paint layer on the surface.
Ph.D. in Mechanical, Materials and Aerospace Engineering, May 2016
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Title: SENTIMENT ANALYSIS BASED ON APPRAISAL THEORY AND FUNCTIONAL LOCAL GRAMMARS
Creator: Bloom, Kenneth
Date: 2011-08, 2011-12
Description: Much of the past work in structured sentiment extraction has been evaluated in ways that summarize the output of a sentiment extraction...
Show moreMuch of the past work in structured sentiment extraction has been evaluated in ways that summarize the output of a sentiment extraction technique for a particular application. In order to get a true picture of how accurate a sentiment extraction system is, however, it is important to see how well it performs at nding individual mentions of opinions in a corpus. Past work also focuses heavily on mining opinion/product-feature pairs from product review corpora, which has lead to sentiment extraction systems assuming that the documents they operate on are review-like | that each document concerns only one topic, that there are lots of reviews on a particular product, and that the product features of interest are frequently recurring phrases. Based on existing linguistics research, this dissertation introduces the concept of an appraisal expression, the basic grammatical unit by which an opinion is expressed about a target. The IIT sentiment corpus, intended to present an alternative to both of these assumptions that have pervaded sentiment analysis research, consists of blog posts annotated with appraisal expressions to enable the evaluation of how well sentiment analysis systems nd individual appraisal expressions. This dissertation introduces FLAG, an automated system for extracting appraisal expressions. FLAG operates using a three step process: (1) identifying attitude groups using a lexicon-based shallow parser, (2) identifying potential structures for the rest of the appraisal expression by identifying patterns in a sentence's dependency parse tree, (3) selecting the best appraisal expression for each attitude group using a discriminative reranker. FLAG achieves an overall accuracy of 0.261 F1 at identifying appraisal expressions, which is good considering the difficulty of the task.
Ph.D. in Computer Science, December 2011
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Title: MINIMIZING MAXIMUM PATH DELAY IN MULTIPATH CONNECTIONS
Creator: Devetak, Fabrizio U
Date: 2013, 2013-07
Description: Minimizing packet delay (or packet latency, as it is often called) is an impor- tant goal in modern telecommunication networks. In a network...
Show moreMinimizing packet delay (or packet latency, as it is often called) is an impor- tant goal in modern telecommunication networks. In a network with given physical and topological characteristics, uneven distribution of tra c between nodes may re- sult in parts of the network being underutilized while other parts may experience congestion and its related e ect of higher delays, and even packet loss if bu ers be- come overloaded. Overload results in longer queuing delays, which are a major, if not the major, source of packet delay. Internet nodes typically route based on a single best (shortest) path without taking into account link occupancy and without taking full advantage of all available network resources. So a method for improving network performance is to allow nodes to use multiple paths to route packets to a given desti- nation. In this research project the main objective is to nd the best algorithm that, applied to a multi-commodity network, produces multi-path ow assignments that minimize the maximum cross-network delay. The motivation for this objective is the tighter requirements for quality of service coming from real-time streaming services, such as voice and video, which restrict the maximum source-destination packet delay. An analytical approach, based on Lagrange Multipliers, was investigated which led to the design of an iterative algorithm that can be proved to converge to the opti- mal path and ow con guration. From that algorithm a simpli ed heuristic algorithm was derived, that achieves results close to optimal. Another heuristic but more intu- itive algorithm, similar to the algorithm described in [6], was also investigated and found to also o ers good results and to be computationally e cient. The two heuristic algorithms were simulated with Java programs and, as a benchmark, the single path algorithm that is commonly used in the Internet was also simulated. That simulation was also done with Java programs. Performance comparisons for the three types of simulations is also provided. For a more realistic evaluation, the intuitive heuristic algorithm was also simu- viii lated in the NS-3 simulation environment (in addition to the Java simulation). NS-3 is a state-of-the-art industry standard widely used in the academic world, and for it a distributed routing protocol, that implements the maximum delay minimization algorithms without centralized control, was designed.
PH.D in Computer Engineering, July 2013
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Title: MATERIAL INVENTORY CONTROL AND MANAGEMENT SYSTEM IN CONSTRUCTION USING GIS APPLICATIONS AND A "HYBRID" TRACKING SYSTEM
Creator: Le, Kiet Tuan
Date: 2017, 2017-05
Description: Material inventory control and management is simply the process by which an organization is supplied with the goods and services that it needs...
Show moreMaterial inventory control and management is simply the process by which an organization is supplied with the goods and services that it needs to achieve its objectives of buying, storing and moving materials. There are usually plenty of materials in a construction site. A large amount of stored materials can meet unexpected demands, and can prevent future purchases that can be affected by an escalation of material prices. However, a large amount of stored materials can also cause negative impacts such as increased costs for storing redundant inventory, and decreased construction productivity. Therefore, a proper material inventory control and management system is critical for economy and efficiency in construction projects. A material inventory control and management system consists of two main elements: inventory control and inventory management. Inventory control is the process of monitoring the flow of materials on the construction site beginning when materials are received from manufacturers and ending when those materials are used in production. Inventory management is the practice overseeing and managing the ordering, storage and use of materials on the construction site. In this study, an automated material inventory control and management system is developed using Geographical Information System (GIS) applications and a “hybrid” tracking system to identify the need for materials, order, track, transport, store, control the inventory, circulate on site, and incorporate into production. The proposed system allows users to have access to real-time information about the materials on the construction such as: the arrival of materials, the amount of materials received, the status of materials (either in storage area or in-production), and the up-to-date information about site stocks. Furthermore, the system provides users the ability to make correct and timely decisions regarding materials on the construction site.
Ph.D. in Civil Engineering, May 2017
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Title: THE TEMPORAL RELATIONSHIP BETWEEN DEPRESSION AND THE CONVERSION TO DEMENTIA: A RETROSPECTIVE ANALYSIS
Creator: Rog, Lauren
Date: 2011-07, 2011-07
Description: A relationship between depression and the dementing process has been fairly well established in both patients with mild cognitive impairment ...
Show moreA relationship between depression and the dementing process has been fairly well established in both patients with mild cognitive impairment (MCI) and dementia (e.g., Apostolova and Cummings, 2008; Lyketsos et al., 2002; Starkstein et al., 2005). However, less clear is the temporal role depression plays in the dementing process, with the possibilities including depression as a risk factor, a prodrome, or a consequence of dementia. Variables that have been considered to affect this relationship include gender, depression severity, lifetime history of depression, and etiology of cognitive decline. The current study examined the temporal relationship between depression and dementia in a sample of 218 patients with MCI or dementia who were seen for at least one follow-up visit at the neuropsychology service of an urban university medical center. Results did not reveal support for either the prodrome or the risk factor hypothesis of the depression-dementia relationship. However, it was found that people with a past history of depression who did not show depressive symptoms concurrent with their cognitive decline converted most quickly to dementia, suggesting a unique depression-dementia relationship in people with earlier-life depression.
Ph.D. in Clinical Psychology, July 2011
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Title: MODELING AND COMPUTATIONAL FLUID DYNAMICS SIMULATION OF A BUBBLING FLUIDIZED BED PROCESS AT DIFFERENT SCALES
Creator: Jang, Jungkee
Date: 2012-11-14, 2012-12
Description: In recent years there has been increased research activity in the experimental and numerical study of gas-solid flow system in the bubbling...
Show moreIn recent years there has been increased research activity in the experimental and numerical study of gas-solid flow system in the bubbling fluidized bed process. The bubbling fluidized bed process have numerous applications in the energy, pharmaceuticals, and chemicals process industries since it has provides a number of advantages such as large heat capacity inside a bed, and rapid heat and mass transfer rate. A reliable design and scale-up approach for a bubbling fluidized bed process requires a very detailed model based on the fundamentals of multiphase transport phenomena. The present works address the simulation and scale-up of rather complex gas-solid flow behavior in bubbling beds using Computational Fluid Dynamics (CFD) approach. The CFD model developed in this study which is based on two fluid model was used to optimize the performance and utilized as a scale-up tool for an isothermal and a non-isothermal bubbling fluidized bed process. For isothermal case, 2-Dimensional and 3-Dimensional simulations of bubbling beds for both PSRI laboratory and large scales fluidized beds using a kinetic theory approach were performed. The FLUENT code was used to conduct the simulations. Our simulation results were validated and refined by comparing them with the laboratory-scale experimental data of PSRI. Then, our modified 2-D and 3-D CFD models were used to predict the large-scale PSRI bubbling fluidized bed performance at different operating conditions. In our 3-D simulations, we used exactly the same bed dimensions and inlet configurations (such as air distributor) as the experimental one to predict the characteristics of gas-solid flow patterns in the PSRI large-scale bubbling fluidized bed. The numerical simulation results compared well with both PSRI large scale experimental xx data on pressure drop and time-averaged void fraction near the wall, which could be a very good proof for demonstrating the capability of CFD as a tool to be used in the design and scale-up of bubbling fluidized bed systems. For non-isothermal case, the set of equations necessary to describe the flow patterns and heat/mass transfer phenomena of bubbling beds at three different scales were developed. CFD simulations were performed to investigate the characteristics of pharmaceutical particle drying process in bubbling fluidized beds at three different scales (e.g., lab, kilo, and 10-kilo scales). The results of CFD simulation were compared with the experimental data obtained at laboratory-scale (Duquesne University experiments), to validate and refine our CFD model. The modified model was used to simulate the drying of the same material in Abbott laboratory kilo and 10-kilo scale units. Our simulation results for solid particles drying as a function of dimensionless time showed that our CFD model along with similar dimensionless group similarity approach can be used as a tool to scale-up the drying process from experimental scale to both kilo-scale and 10-kilo scale fluidized bed dryer. Moreover, to determine the optimum particle mixing, numerical simulations were performed at different particle diameters, bed heights, inlet velocities and inlet velocity distributions, respectively. The numerical simulation results compared well with the experimental data (performed by Duquesne University and Abbott laboratory) on moisture removal rate and outlet gas temperature. This also could be a very good proof for demonstrating the capability of CFD as a tool to be used in the design and scale-up of non-isothermal bubbling fluidized bed processes.
PH.D in Chemical Engineering, December 2012
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