The purpose of the present study was to investigate the role of pitch contours in directing infant attention to adult speech. Several studies have shown that infants from a few days old to 9 months of age prefer infant-directed (ID) over adult-directed (AD) speech. Moreover, 4-month-olds have been shown to prefer pitch contours that simulate ID speech, suggesting that the exaggerated pitch contours are necessary for infant attention. The current study investigated this attentional preference utilizing ID and AD pitch contours in a fixation-based preference procedure. Results from the first experiment failed to show a similar preference for the ID pitch contours. Because a lack of preference could have been due to a failure to discriminate, a habituation study was also conducted. The results from the second experiment showed that 4-month-olds can discriminate the ID and AD pitch contours. From these results, it is argued that the pitch contour may be but one of many possible prosodic characteristics that attract infant attention and this attention may occur only within a language context. It is suggested that future studies investigate ID speech using a more context-dependent procedure, where natural or more complete speech samples are utilized. / Master of Science

In this thesis, we focus on the steady state properties of two systems which are genuinely out of equilibrium. The first project is an application of dynamic field theory to a specific non equilibrium critical phenomenon, while the second project involves both simulations and analytical calculations. The methods of field theory are used on both these projects. In the first part of this thesis, we investigate a generalization of the well-known field theory for directed percolation (DP). The DP theory is known to describe an evolving population, near extinction. We have coupled this evolving population to an environment with its own nontrivial spatio-temporal dynamics. Here, we consider the special case where the environment follows a simple relaxational (model A) dynamics. We find two marginal couplings with upper critical dimension of four, which couple the two theories in a nontrivial way. While the Wilson-Fisher fixed point remains completely unaffected, a mismatch of time scales destabilizes the usual DP fixed point. Some open questions and future work remain. In the second project, we focus on a simple particle transport model far from equilibrium, namely, the totally asymmetric simple exclusion process (TASEP). While its stationary properties are well studied, many of its dynamic features remain unexplored. Here, we focus on the power spectrum of the total particle occupancy in the system. This quantity exhibits unexpected oscillations in the low density phase. Using standard Monte Carlo simulations and analytic calculations, we probe the dependence of these oscillations on boundary effects, the system size, and the overall particle density. Our simulations are fitted to the predictions of a linearized theory for the fluctuation of the particle density. Two of the fit parameters, namely the diffusion constant and the noise strength, deviate from their naive bare values [6]. In particular, the former increases significantly with the system size. Since this behavior can only be caused by nonlinear effects, we calculate the lowest order corrections in perturbation theory. Several open questions and future work are discussed. / Ph. D.

As directed energy technology continues to evolve and become a viable weapon alternative, a need exists to investigate the impacts of these applications without a "plug-and-check" method, but rather with an analysis governed by fundamental principles. This thesis examines the transient thermal loads that a high-energy weapon system introduces into a high performance aircraft using fundamental thermodynamic and heat transfer analyses. The high-energy weapon system employed in this research contains power storage, power conditioning equipment, optics, and a solid-state laser. The high-energy weapon system is integrated into the aircraft by a dedicated thermal management system connected to the onboard air and fuel fluid networks. The dedicated thermal management system includes heat exchangers, thermal storage, microchannel coolers, valves, and pumps. Governing equations for the electric directed energy weapon subsystem and thermal management system are formulated for each system component and modeled in Mathwork's Simulink™. System models are integrated into a generic, high-performance aircraft model created as part of the Air Force Research Laboratory's Integrated Vehicle Energy Technology Demonstration (INVENT) program. The aircraft model performs a defined mission profile, firing the directed energy weapon during the high-altitude, transonic cruise segment. When firing a 100-kilowatt directed energy weapon system operating at 16.9% efficiency, large thermal transients quickly heat downstream onboard systems. Real-time heat rejection causes temperature spikes in avionic and environment systems that exceed allowable operation constraints. The addition of thermal storage to the thermal management system mitigates thermal impacts downstream of the directed energy weapon by delaying the time thermal loads are rejected to aircraft, thereby reducing peak and average loads. Although thermal storage is shown to mitigate peak loads in downstream onboard systems, thermal closure is yet to be achieved. This research presents a general and fundamental approach to investigating the thermal impacts of a directed energy weapon system on a high-performance aircraft. Although specific cases are analyzed, this general approach to model development and simulation is conducive to component and system customization for many other cases. Additionally, the supplementation of models with analytical, semi-empirical, and empirical data further tailors model development to each user's need while increasing the potential to enhance accuracy and efficacy. Without the material expenses of a "plug-and-check" method, component and system level modeling of the directed energy weapon system and high-performance aircraft provides valuable insight into the thermal responses of highly-coupled systems. / Master of Science

A recent study by Polka, Rvachew, and Molnar (2008) found that 6- to 8-month-old infants do not discriminate a simple native consonant-vowel contrast when familiarized to it in the presence of distraction noise (i.e., recordings of crickets and birds chirping), even when testing was conducted in quiet. Because the distraction noise did not overlap with the phonemes' frequencies, failure to encode the familiarization phoneme could be due more to a disruption in infant attention than to direct masking effects. Given that infants learn speech under natural conditions involving noise and distraction, it is important to identify factors that may 'protect' their speech perception under non-ideal listening conditions. The current study investigated three possible factors: speech register, face information, and speaker gender. Six-month-old infants watched a video of a female speaker producing a native phoneme in either an adult-directed or infant-directed manner accompanied by the same background noise as in Polka et al. (2008). After habituation, infants were tested with alternating trials of the familiar phoneme and a novel phoneme in quiet. Phoneme discrimination was measured by recording infants' heart rate and looking times during familiar and novel trials. Discrimination was poor in infants who viewed a female speaker using adult-directed speech but was significantly improved (as seen in both dependent measures of attention) when the female speaker used infant-directed speech. Results indicate that common factors in the typical environment of infants can promote speech perception abilities in noise. / Master of Science

Continuous advances in VLSI technology have led to more complex digital designs and shrinking transistor sizes. Due to these developments, design verification and manufacturing test have gained more importance and 70 % of the design expenditure in on validation processes. Electronic Design Automation (EDA) tools play a huge role in the validation process with various verification and test tools. Their efficiency have a high impact in saving time and money in this competitive market. Direct Acyclic Graphs (DAGs) are the backbone for most of the EDA tools. DAG is the most efficient data structure to store circuit information and also have efficient backt traversing structure which help in developing reasoning/ debugging tools. In this thesis, we focus on two such EDA tools using graphs as their underlying structure for circuit information storage • Scan pattern Debugger for Partial Scan Designs • Circuit SAT Bounded Model Checkers We developed a complete Interactive Scan Pattern Debugger Suite currently being used in the industry for next generation microprocessor design. The back end is an implication graph based sequential logic simulator which creates a Debug Implication Graph during the logic simulation of the failing patterns. An efficient node traversal mechanism across time frames, in the DIG, is used to perform the root-cause analysis for the failing scan-cells. In addition, the debugger provides visibility into the circuit internals to understand and fix the root-cause. We integrated the proposed technique into the scan ATPG flow for industrial microprocessor designs. We were able to resolve the First Silicon logical pattern failures within hours, which would have otherwise taken a few days of manual effort for root-causing the failure, understanding the root-cause and fixing it. For our circuit SAT implementation, we replace the internal implication graph used by the SAT solver with our debug implication graph (DIG). There is a high amount of circuit unrolling in circuit SAT/ BMC (Bounded Model Checking) problems which creates copies of the same combinational blocks in multiple time frames. This allows us to use the repetitive circuit structure and club it with the CNF database in the SAT solver. We propose a new data structure to store data in a circuit SAT solver which results up to 90% reduction in number of nodes. / Master of Science

It is well known that people who use drugs (PWUD) leave the hospital via patient directed discharge (“PDD”; also known as against medical advice “AMA”) more often than people who do not use drugs. The introduction of xylazine – a veterinary tranquilizer – into the United States (US) synthetic opioid supply has only exacerbated this situation. The following paper reviews the literature on xylazine, hospitalization with opioid use disorder (OUD), and how xylazine has changed the experience of hospitalization with OUD. The research revealed that xylazine causes respiratory depression, sedation, and the formation of necrotic wounds. There is currently no treatment for xylazine dependence, overdose, or withdrawal. The literature further revealed that inadequate management of withdrawal and pain, along with stigma from health professionals, are major reasons why PWUD leave the hospital PDD before completing treatment. The difficulty the health system faces with the management of xylazine withdrawal and the necrotic wounds it produces only exacerbates this problem and necessitates increased attention to this topic. Using opioid agonists to treat withdrawal decreases rates of PDD for PWUD in the hospital. This paper will argue that the treatment of PWUD in the hospital with opioid agonists in order to address withdrawal and pain is ethically necessary; and that the introduction of xylazine into the synthetic opioid supply in the US only further necessitates the collective adoption of this viewpoint. / Urban Bioethics

Thesis (Ed.D.)--Boston University / PLEASE NOTE: Boston University Libraries did not receive an Authorization To Manage form for this thesis or dissertation. It is therefore not openly accessible, though it may be available by request. If you are the author or principal advisor of this work and would like to request open access for it, please contact us at open-help@bu.edu. Thank you. / The purpose of this study was to determine whether a match between a participant's learning style and type of online instruction improved learner performance on tests measuring comprehension and retention. Learning style was measured by the Self-Directed Leamer Readiness Scale (SDLRS) and the Grasha-Riechmann Student Learning Style Scale (GRSLSS) and online instruction varied among online courses, recorded online courses, and computer-based tutorials. The setting for the study was a high tech machine vision company in Massachusetts and online users of its products were the participants. Three groups of learners participated in the study: employees, high school students, and customers. All three groups were comprised of engineers or engineering students. All 106 participants completed a survey that measured their preference for self-directed and collaborative learning style with the standard instruments SDLRS and GRSLSS. Participants completed 323 pre- and post-tests for 46 live online courses, recorded online courses, and computer-based tutorials during the data collection phase of the study. Those participants learning in their preferred learning style had the highest mean improvement from pre- to post-tests. Those participants with average or below average scores for self-directed and collaborative learning style showed the least improvement. The results of this study supported the hypothesis that matching the type of activity, collaborative or self-directed, to the learner's preferred learning style improved performance. The study included ten research questions. / 2999-01-01

<p dir="ltr">This dissertation introduces a novel graph embedding paradigm, leveraging a force-directed scheme for graph embedding. In the field of graph embedding, an "embedding" refers to the process of transforming elements of a graph such as nodes, or edges, or potentially other structural information of the graph into a low-dimensional space, typically a vector space, while preserving the graph's structural properties as much as possible. The dimensions of the space are supposed to be much smaller than the elements of the graph that are to be embedded. This transformation results in a set of vectors, with each vector representing a node (or edge) in the graph. The goal is to capture the essence of the graph's topology, node connectivity, and other relevant features in a way that facilitates easier processing by machine learning algorithms, which often perform better with input data in a continuous vector space.</p><p dir="ltr">The main premise of kinematics-based force-directed graph embedding is that the nodes are considered as massive mobile objects that can be moved around in the embedding space under force. In this PhD thesis, we devised a general theoretical framework for the proposed graph embedding paradigm and provided the mathematical proof of convergence given the required constraints. From this point on, the objective was to explore force functions and parameters and methods of applying them in terms of their efficacy regarding graph embedding applications. We found some force functions that outperformed the state-of-the-art methods.</p><p dir="ltr">The author of this manuscript believes that the proposed paradigm will open a new chapter, specifically in the field of graph embedding and generally in the field of embedding.</p>

No / The duocarmycins belong to a class of agent that has fascinated scientists for over four decades. Their exquisite potency, unique mechanism of action, and efficacy in multidrug-resistant tumour models makes them attractive to medicinal chemists and drug hunters. However, despite great advances in fine-tuning biological activity through structure-activity relationship studies (SARS), no duocarmycin-based therapeutic has reached clinical approval. In this review, we provide an overview of the most promising strategies currently used and include both tumour-targeted prodrug approaches and antibody-directed technologies.

Infant speech perception develops within the context of specific language experience. While there is a corpus of empirical evidence concerning infants' perception of linguistic and prosodic information in speech, few studies have explored the interaction of the two. The present investigation was designed to combine what is known about infants' perception of nonnative phonemes (linguistic information) with what is known about infant preferences for ID speech (prosodic information). In particular, the purpose of this series of studies was to examine infant preferences for ID speech within the timeline of the phonemic perceptual reorganization that occurs at the end of the first postnatal year. In Experiment 1, 20 Native-English 10- to 11-month-old infants were tested in an infant-controlled preference procedure for attention to ID speech in their native language versus ID speech in a foreign language. The results showed that infants significantly preferred the ID-native speech. In Experiment 2, the preferred prosodic information (ID speech) was separated from the preferred linguistic information (native speech), as a means of discerning the relative perceptual draw of these types of speech characteristics. Specifically, a second group of 20 10- to 11-month-old infants was tested for a preference between ID speech in a foreign language and AD speech in their native language. In this case the infants exhibited a significant preference for ID-foreign speech, suggesting that prosodic information in speech has more perceptual weight than linguistic information. This pattern of results suggests that infants attend to linguistic-level information by 10- to 11-months of age, and that ID speech may play a role in the native-language tuning process by directing infants' attention to linguistic specifics in speech. / Master of Science