VictorJuiz/thesis huggingface dataset:
Cognitive and Auditory Factors Underlying Auditory Spatial Attention in Younger and Older Adults

Listening to speech with competing speech in the background is challenging and becomes harder with age. Three experiments examined the auditory and cognitive aspects of auditory spatial attention in conditions in which the location of the target was uncertain. In all experiments, word identification was measured for target sentences presented with two competitor sentences. On each trial, the three sentences were presented with one from each of three spatially separated loudspeakers. A priori cues specified the location and identity callsign of the target. In Experiments I and II, sentences were also presented in conditions of simulated spatial separation achieved with the precedence effect. Participants were younger and older adults with normal hearing sensitivity below 4 kHz. For both age groups, the contributions of richer acoustic cues (those present when there was real spatial separation, but absent when there was simulated spatial separation) were most pronounced when the target occurred at “unlikely” spatial listening locations, suggesting that both age groups benefit similarly from richer acoustical cues. In Experiment II, the effect of time between the callsign cue and target word on word identification was investigated. Four timing conditions were tested: the original sentences (which contained about 300 ms of filler speech between the callsign cue and the onset of the target words), or modified sentences with silent pauses of 0, 150, or 300 ms replacing the filler speech. For targets presented from unlikely locations, word identification was better for all listeners when there was more time between the callsign cue and key words, suggesting that time is needed to switch spatial attention. In Experiment III, the effects of single and multiple switches of attention were investigated. The key finding was that, whereas both age groups performed similarly in conditions requiring a single switch of attention, the performance of older, but not younger listeners, was reduced when multiple switches of spatial attention were required. This finding suggests that difficulties disengaging attention may contribute to the listening difficulties of older adults. In conclusion, cognitive and auditory factors contributing to auditory spatial attention appear to operate similarly for all listeners in relatively simple situations, and age-related differences are observed in more complex situations.

Keywords: attention
audition
aging
spatial hearing
Advisor: Pichora-Fuller, Margaret Kathleen
Stress-wave Induced Fracture in Rock due to Explosive Action

Blasting is a complex phenomenon and many parameters affect the outcome of a blast. The process of rock fragmentation by blasting is not well understood yet. Therefore, as a first step, blast-induced dynamic fractures must be studied under highly controlled conditions. The whole cycle of conducting a series of laboratory-scale blast, analyzing the results, and using them to test the validity of an advanced numerical code is reported in this thesis. Initially, the respective contributions by both shock energy and gas energy fractions in an explosive in the blasting process are explained. Then, microstructural, physical and mechanical properties of Laurentian and Barre granites as the selected rock types are investigated. Explosively driven fractures in a blast are controlled by rock and explosive properties, coupling media and coupling ratio. Sample geometries, types of explosives and coupling media used in the experiments are explored in the next step. In order to isolate the effect iii of shock energy from the gas energy in explosively driven fractures, copper liners were installed in the blast holes to prevent gas penetration into the shock induced cracks. The aim of the experiments was to study exclusively the nature of shock-driven fractures, and to contain the dynamic fractures within the samples and avoid sample fragmentation. At the same time and in order to investigate the stress field as a function of distance from the borehole, pressure gauges were installed in the samples. The measured pressures were used in a numerical-experimental procedure to estimate the attenuation properties of the rocks. Blasted samples were cut and impregnated with a mix of epoxy and fluorescent dye. Next, dynamic fracture patterns were highlighted using a strong ultraviolet source. After taking photographs, fracture patterns were manually mapped and crack densities were calculated at different depths and distances from the boreholes. The parameters that affect the development of dynamic fracture patterns are also discussed and relation between crack densities and pressures applied by explosives are investigated. Finally, the dynamic fracture patterns and measured pressures will be used for calibrating the selected equation of state, strength and failure models implemented in AUTODYN. Governing equations, the procedure for obtaining the model constants, applicability of the selected model for predicting the blast experiments and its limitations are discussed in detail.

Keywords: Autodyn
Dynamic Fracture
Laboratoy-scale
Simulation
Granite
Blasting
Advisor: Mohanty, Bibhu
Aerosol Characterization and Analytical Modeling of Concentric Pneumatic and Flow Focusing Nebulizers for Sample Introduction

A concentric pneumatic nebulizer (CPN) and a custom designed flow focusing nebulizer (FFN) are characterized. As will be shown, the classical Nukiyama-Tanasawa and Rizk-Lefebvre models lead to erroneous size prediction for the concentric nebulizer under typical operating conditions due to its specific design, geometry, dimension and different flow regimes. The models are then modified to improve the agreement with the experimental results. The size prediction of the modified models together with the spray velocity characterization are used to determine the overall nebulizer efficiency and also employed as input to a new Maximum Entropy Principle (MEP) based model to predict joint size-velocity distribution analytically. The new MEP model is exploited to study the local variation of size-velocity distribution in contrast to the classical models where MEP is applied globally to the entire spray cross section. As will be demonstrated, the velocity distribution of the classical MEP models shows poor agreement with experiments for the cases under study. Modifications to the original MEP modeling are proposed to overcome this deficiency. In addition, the new joint size-velocity distribution agrees better with our general understanding of the drag law and yields realistic results.

Keywords: Aerosol Characterization
Concentric Nebulizer
Flow Focusing Nebulizer
Sample Introduction
MEP modeling
Advisor: Mostaghimi, Javad
Case in Standard Arabic: The Untraveled Paths

This thesis proposes a novel theory to account for the structural Case facts in Standard Arabic (SA). It argues that structural Nom and Acc Cases are licensed by Verbal Case (VC). Thus it argues against the proposal that structural Case in SA is licensed as a reflex of phi-agreement (Schütze 1997 and Chomsky 2001 crosslinguistically, and Soltan 2007 for SA), and also against the view that structural Case is a [uT] feature on the DP (Pesetsky & Torrego 2001, 2004). After arguing against these two approaches, it is shown that verbless sentences, where the verb is not licensed (by VC), do not witness the licensing of structural Case. Thus verbless sentences provide a context where verbs are not licensed, similar to the embedded subject position of control verbs like ‘try’ (where lexical DPs are not licensed). Investigation of the SA verbal system reveals that SA verbs are licensed through Case checking/assignment by verbal particles. Thus, like DPs, verbs receive a form of Case, which I call VC, represented as unvalued [VC] features on I and v*. Since the VC-assigning particles are Comp elements, I propose that [VC] is valued on I and v* by a valued [VC] feature on Fin (via Agree), which enables I and v* to value the [Case] features on the subject and object as Nom and Acc, respectively. Thus the DP is licensed by the same feature that licenses the verb, which is VC. Given the observation that [T], [phi], and [Mood] do not license Case in SA, I argue for two types of finiteness, Infl-finiteness, related to [T], [Mood], and [phi], and Comp-finiteness, related to [VC]. To account for the Case facts in various SA sentence types, I propose that Fin0 has a [VC] feature iff it selects an XP that has (at least) one I-finiteness feature ([T], [Mood], [phi]) and a categorial [V] feature.

Keywords: Case Theory
Standard Arabic
Advisor: Massam, Diane
Identification and Characterization of a Novel CK2-MSK2 Iinteraction in the UV Response

CK2 is a ubiquitous serine/threonine protein kinase implicated in numerous cellular processes as well as in tumorigenesis. CK2 is composed of two catalytic (αα, αα’, α’α’) subunits and two regulatory (ββ) subunits that assemble to form the active CK2 holoenzyme. CK2 has been shown to phosphorylate, interact with, and regulate other proteins, including other protein kinases. CK2 substrates can be initially bound by the CK2β regulatory subunit, which acts as a docking site to facilitate phosphorylation and mediate CK2 substrate specificity. In a screen to identify novel CK2β interacting proteins, I identified three novel CK2β interactors, including the mitogen- and stress-activated kinase 2 (MSK2), which I pursued for further characterization. MSK2, and the closely related isoform MSK1, are nuclear kinases that are activated following mitogen stimulation or cellular stress, including UV radiation, by the ERK1/2 and p38-MAPK signaling cascades, respectively. However, factors that differentially regulate MSK1 and MSK2 have not been well characterized. In my thesis, I demonstrate that CK2, which contributes to NF-κB activation following UV radiation in a p38-dependent manner, physically interacts with MSK2 but not MSK1 and that CK2 inhibition specifically impairs UV-induced MSK2 kinase activation. A putative site of CK2 phosphorylation was mapped to MSK2 residue serine-324 and when substituted to alanine (S324A) also compromised MSK2 activity. RNA interference-mediated depletion of MSK2 in human MDA-MB-231 cells, but not MSK1 depletion, resulted in impaired UV-induced phosphorylation of NF-κB p65 at serine-276 in vivo, which was restored by the ectopic expression of MSK2 but not by MSK2-S324A. Furthermore, UV-induced p65 transactivation capacity was dependent on MSK2, MSK2 residue S324, and p65-S276. These results suggest that MSK1 and MSK2 are differentially regulated by CK2 during the UV response and that MSK2 is the major protein kinase responsible for the UV-induced phosphorylation of p65 at S276 that positively regulates NF-κB activity in MDA-MB-231 cells.

Keywords: CK2
MSK2
UV response
NF-kappaB
Advisor: Koch, Christine Anne
Flexible Computing with Virtual Machines

This thesis is predicated upon a vision of the future of computing with a separation of functionality between core and edges, very similar to that governing the Internet itself. In this vision, the core of our computing infrastructure is made up of vast server farms with an abundance of storage and processing cycles. Centralization of computation in these farms, coupled with high-speed wired or wireless connectivity, allows for pervasive access to a highly-available and well-maintained repository for data, configurations, and applications. Computation in the edges is concerned with provisioning application state and user data to rich clients, notably mobile devices equipped with powerful displays and graphics processors. We define flexible computing as systems support for applications that dynamically leverage the resources available in the core infrastructure, or cloud. The work in this thesis focuses on two instances of flexible computing that are crucial to the realization of the aforementioned vision. Location flexibility aims to, transparently and seamlessly, migrate applications between the edges and the core based on user demand. This enables performing the interactive tasks on rich edge clients and the computational tasks on powerful core servers. Scale flexibility is the ability of applications executing in cloud environments, such as parallel jobs or clustered servers, to swiftly grow and shrink their footprint according to execution demands. This thesis shows how we can use system virtualization to implement systems that provide scale and location flexibility. To that effect we build and evaluate two system prototypes: Snowbird and SnowFlock. We present techniques for manipulating virtual machine state that turn running software into a malleable entity which is easily manageable, is decoupled from the underlying hardware, and is capable of dynamic relocation and scaling. This thesis demonstrates that virtualization technology is a powerful and suitable tool to enable solutions for location and scale flexibility.

Keywords: Virtualization
Cloud Computing
Operating Systems
Thin Clients
Scalability
Migration
Advisor: Lara, Eyal de
Polymers as Multidentate Ligands for Surface Modification and Hierarchical Organization of Colloidal Quantum Dots

This thesis describes the design and synthesis of homopolymers and copolymers for tuning surface properties of colloidal semiconductor quantum dots (QDs), and directing QD self-assembly to create well-defined 3D structures in which the spatial organization of QDs and other functional materials (e.g. conjugated polymers) is properly controlled. A common feature of all of the polymers described in this thesis is that they contain multiple pendant anchoring groups such as tertiary amines, pyridines and acrylic acids, which bind strongly to QD surfaces as multidentate ligands. This thesis starts by describing a quantitative analytical method based on size exclusion chromatography (SEC) to characterize the interaction of poly(2-N,N-dimethylaminoethyl methacrylate) (PDMA) with TOPO-coated CdSe QDs. In addition, the separation of polymer-bound QDs from excess free polymer can be scaled up by preparative high-performance liquid chromatography. The second part of this thesis explores a method to disperse CdSe and core/shell CdSe/ZnS QDs into water using a poly(ethylene glycol-b-N,N-dimethylaminoethyl methacrylate) (PEG–b–PDMA) diblock copolymer. Alternatively, statistical copolymers, such as poly(oligoethyleneglycol)-co-PDMA (POEG-co-PDMA) and poly(N,N-dimethylacrylamide)-based statistical copolymers carrying pendant pyridine or imidazole groups play the same role as PEG–b–PDMA for dispersion of the QDs into water. The third part of this thesis describes the synthesis and characterization of a water-soluble pH-responsive PDMA-grafted polythiophene (denoted as PT-g-PDMA). The relatively rigid and extended conformation of the polythiophene backbones provides new opportunity for studying the correlation of between optical responses of conjugated polymers and their conformational transitions. In addition, the favorable interaction between the PDMA arms of PT-g-PDMA and CdSe nanorods allows enhanced interface-compatibility of the nanorods with the polythiophene backbone. The last part of this thesis presents a straightforward and versatile approach to achieving nanoscale co-organization of colloidal QDs (e.g. CdSe, CdSe/ZnS core/shell or PbS QDs) with conjugated polymers (e.g. poly(3-hexylthiphene)) by using polymer micelles of poly(styrene-b-4-vinylpyridine) as the structural motif. The spatially defined organization allows photoinduced excited state interaction between the QDs and poly(3-hexylthiphene) at the micellar interface, reminiscent of structures of light harvesting complexes in nature. This strategy is also applicable to other morphologies of polymer self-assemblies, such as poly(styrene-b-acrylic acid) (PS-b-PAA) vesicles.

Keywords: Polymers
Quantum dots
Advisor: Winnik, Mitchell A.
Mindfulness-based Wellness Education: A Longitudinal Evaluation with Students in Initial Teacher Education

Mindfulness-based wellness education (MBWE) is an 8-week program teaching formal mindfulness practices as a foundation for cultivating an awareness of one’s health or ill-health in the physical, social, emotional, ecological, vocational, mental and spiritual domains of human existence. It is designed as a health promotion intervention for individuals who are at risk of developing stress related problems, such as is the case of human services professionals. This dissertation focuses on teachers-in-training. Two groups of teacher trainees completed MBWE as part of an elective course focusing on stress and burnout. In comparison to control participants, who completed other optional courses, MBWE participants experienced improvements in mindfulness, health, and teaching self-efficacy. In one group, the intervention was also effective in reducing psychological distress and augmenting satisfaction with life. Interviews with participants after graduation revealed that although they struggled with independent mindfulness practice, they benefited from their participation in the class, which led to specific health behavior changes such as increased physical activity. Some participants reported that they relied on their mindfulness practices in times of crisis; others shared the knowledge they learned with their students and observed that this was an effective and beneficial response to the needs of their classrooms. Ideas for future inquiries include the need to explore factors influencing participants’ responses to the MBWE program and how to support on-going practice.

Keywords: Mindfulness
Human Services Professionals
Stress
Health Promotion
Wellness
Teacher Education
Advisor: Schneider, Margaret
Development of Microencapsulation-based Technologies for Micronutrient Fortification in Staple Foods for Developing Countries

A microencapsulation-based technology platform for effective delivery of multiple micronutrients for food fortification has been developed. The technology, consisting of extrusion agglomeration followed by encapsulation through surface coating, has been successfully tested on three size scales in typical staple foods: as a surface treatment on salt and sugar, on 20-100µm scale; in salt on a 300-1200 μm scale; and on reconstituted rice on the 5-10 mm scale. The process results in effective delivery systems for one or more active ingredients with organoleptic properties that are unnoticeable to the average consumer. Particularly, salt double fortified with iodine and iron using the microencapsulated ferrous fumarate premix made by the extrusion-based agglomeration process had acceptable sensory properties and stability when stored at 40oC and 60% relative humidity (RH) for up to a year. In these tests >85% of iodine and >90% of ferrous iron were retained. Reconstituted Ultra Rice® grains made by extrusion stabilized by internal gelation has resulted in improved grain integrity and a much simplified process, compared to the original, patented surface crosslinking technique. The most effective internal gelation system is composed of alginate, calcium sulphate (CaSO4), and sodium tripolyphosphate (STPP) at a best ratio of 3%:3%:0.6% (w/w). It is feasible to incorporate folic acid into the existing fortification programs using the technology platform developed in this study. The results indicate that the potential interactions of folic acid with other added micronutrients or with the food vehicles could be prevented by incorporating folic acid as a premix made by the extrusion-based technology. Virtually no folic acid was lost after 9 months storage at 40oC and 60% RH when the folic acid premix was added into salt or sugar samples. The technical feasibility of the microencapsulation-based technology platform has been successfully demonstrated for micronutrient delivery in food vehicles of different size ranges, resulting in fortified staple foods with desired physical, chemical, nutritional, and organoleptic properties. The technology should be adaptable to formulating customized delivery systems of active ingredients for broader applications, and promises to bring immediate benefits in combatting micronutrient deficiencies, that will have far reaching effects in health and social development.

Keywords: Microencapsulation
fortification
micronutrients
staple foods
Advisor: Diosady, Levente L.
Ultra-sensitive Detection of Nucleic Acids using an Electronic Chip

The detection of particular genetic sequences aids in the early detection and diagnosis of disease; permits monitoring of the health and state of the natural environment; and informs forensic investigations. To date, gene detection has relied on enzymatic amplification followed by optical readout. Though these technologies have advanced dramatically, the instruments and assays are costly and lack portability. The work presented herein addresses an urgent challenge: molecular diagnostics at the point-of-need. This work reports the first electronic chip capable of analyzing - directly, without amplification, and with clinically-relevant sensitivity - multiple genes of interest present in a clinical sample. It reports a dramatic acceleration in sample-to-answer times, with clinically actionable findings in minutes where legacy techniques take hours or days. The key to the sensitivity and speed of the biosensors reported herein lies in their architecture and morphology on multiple lengthscales. It is proven that hybridization-based assays employing a nucleic probe attached to a solid surface can only achieve efficient performance when displayed on a nanotextured surface. It is also discovered that these same sensing elements must reach tens of micrometers into solution to achieve rapid, sensitive detection of nucleic acids in clinical samples. As a result, the materials integrated onto the sensing chip reported herein are engineered on multiple lengthscales - from the nanometers to the tens of micrometers. Engineering is done through a combination of low-cost, convenient top-down photolithographic patterning; combined with hierarchically-designed bottom-up growth of electrodeposited sensing elements. The capstone of this work is a chip that distinguishes among different types of bacteria in an unpurified sample. The chip gives accurate answers in under half an hour when detecting bacteria at a level of 1.5 colony-forming-unit (cfu) per microliter. These speeds and sensitivies enable the application of this technology in point-of-need assays for infectious disease detection. Ultimately, the work showcases the power of bringing together techniques and principles from materials chemistry, biochemistry, applied physics, and electrical engineering to the solution of an important problem relevant to human health.

Keywords: Biosensing
electronic chip
DNA detection
nucleic acid detection
Advisor: Sargent, Edward H.