<p>  </p> <p>There is a plethora of information surrounding the stages of infant vocal development, and canonical babble’s predictive power concerning future language outcomes. However, there is less information regarding how the acoustic features of early babble differ between canonical and non-canonical syllable types over the course of development. Furthermore, previous studies rely on small sample sizes which limit their findings’ generalizability. This project examined the pitch range, mean pitch, and syllabic nuclei duration of monosyllabic canonical and non-canonical infant vocalizations over the course of development. </p> <p>Audio files of monosyllabic utterances were obtained from 29 infants at low risk for developing a speech or language disorder, aged 10-26 months. The infants were divided into three age bands: 10-12 months (M=11.74, N=10, 5=F), 13-22 months (M=16.08, N=9, 6=F), and 23-26 months (M=24.67, N=9, 2=F). We listened to each utterance and marked syllable nucleus boundaries prior to running scripts to measure acoustic cues. Between 6 and 15 utterances were selected from each participant. The number of canonical utterances was matched to the number of noncanonical utterances (e.g., if 13 canonical utterances were selected for a specific participant, 13 non-canonical utterances were also selected). We then ran a Praat script which yielded the mean pitch, pitch range, and duration of the syllabic nucleus for each audio file. </p> <p>We found that there was a significant effect of syllable type on duration, as canonical syllables were shorter in duration than non-canonical syllables (F (1, 618.34) = 10.64, <em>p </em>= .001), and on mean pitch, as canonical syllables were lower in mean pitch than non-canonical syllables (F (1, 618.57) = 7.18, <em>p</em> = .008). We did not find an effect of syllable type on pitch range, age on mean pitch or duration, or any interaction effects between syllable type and age. However, we did find an effect of age on pitch range, because infants in the oldest age bracket (23-26 months) were more likely to have a wider pitch range than younger infants (F (2, 44.77) = 5.05, <em>p</em> = .011). </p> <p>This provides preliminary evidence that there are pitch and duration distinctions between canonical and non-canonical syllable types and suggests that as infants age they are more likely to use greater pitch variation within their vocalizations. However, as our study only examined monosyllabic utterances, further research is necessary in order to thoroughly investigate pitch and duration distinctions present in canonical and non-canonical syllables. </p>

This study explored the effects of lecture speech rate and duration on L1 Chinese listeners' listening comprehension of online L2 English lectures on free-recall and cued-recall questions. There are many factors that may affect a Chinese listener's listening comprehension of online English lectures. The current study focused specifically on the effects of speech rate and duration, and explored the possibility of identifying tools that listeners might use to control these factors during online lectures in order to achieve better learning experiences. Using an exploratory quasi-experimental approach, this study explored the research questions in three phases: 1) An initial quasi-experiment was conducted via Qualtrics and applied as a pilot study; 2) The quasi-experiment was revised, with a new link sent out to potential participants from both the United States and China; and 3) Quasi-experiment responses were collected and analyzed. Based on 28 participant responses, the findings from the current study suggest that the interaction between speech rate and duration impacted L1 Chinese listener's comprehension of online L2 English lectures. The findings also suggest that study participants' responses on various types of questions were affected differently by the speech rate and duration of the lectures. / Doctor of Philosophy / It is assumed that the slower and the shorter the listening material is, the better the foreign language learner's listening comprehension will be. Is this true? This study explored how a lecture's speech rate and duration may affect L1 Chinese listeners' listening comprehension of online L2 English lectures on free-recall and cued-recall questions. It discusses the possibility of identifying tools for listeners to control the speech rate and duration of online lectures in order to help listeners achieve better learning experiences. Using an exploratory quasi-experimental approach, this study explored the research questions in three phases: 1) An initial quasi-experiment was conducted via Qualtrics and applied as a pilot study; 2) The quasi-experiment was revised, with a new link sent out to potential participants from both the United States and China; and 3) Quasi-experiment responses were collected and analyzed. Based on 28 participant responses, the findings from the current study suggest that speech rate and duration worked together to impact L1 Chinese listeners' comprehension of online L2 English lectures. The findings also suggest that study participants' responses on various types of questions were affected differently by the speech rate and duration of the lectures.

Real-time control of traffic diversion during non-recurrent congestion continues to be a challenging topic. Especially, with the advent of Intelligent Transportation Systems (ITS), the need for models and algorithms that will control the diversion in real-time, responding to the current traffic conditions has become evident. Several researchers have tried to solve this on-line control problem by adopting different approaches such as, expert systems, feedback control, and mathematical programming. In order to ensure the effectiveness of real-time traffic diversion, an implementation framework capable of predicting the impact of the incident on the traffic flow, generating feasible alternate routes in real-time, and controlling traffic in order to achieve a pre-set goal based on a system optimal or a user equilibrium concept is required. In this dissertation, a framework that would satisfy these requirements is adopted consisting of a "diversion initiation module", a "diversion strategy planning module", and a "control and routing module" which determines the route guidance commands in real-time. The incident duration data collected by the Northern Virginia incident management agencies is analyzed to determine major factors that affect the incident clearance duration. Next, prediction/decision trees are developed for different types of incidents. Based on the validation of these trees using the data that is not employed for the development of the trees, it is found that they perform well for the majority of the incidents. A simple deterministic queuing approach is used to predict the delays that will be caused by the incident for which the clearance duration is predicted using the prediction/decision trees. The diversion strategy planning module, Network Generator, is developed as a knowledge based expert system that uses simple expert rules in conjunction with historical and realtime data to determine the incident impact zone, and to eliminate links that are not suitable for diversion. Finally, it generates alternate routes for diversion using this modified network. Network generator is tested using simulation on a small portion of the Fairfax network. Finally, feedback control models for dynamic traffic routing models, both in distributed and lumped parameter settings, are developed. Methods for developing controllers for these models are also discussed. Two heuristic and analytic feedback controllers for the space discretized lumped parameter models are developed and their effectiveness for realtime traffic control is shown by simulating several scenarios on a simple network. An analytic feedback controller is also designed using a feedback linearization technique for the space discretized model. This controller also performed very well during simulations of various scenarios and proved to be an effective solution to this feedback control problem. / Ph. D.

As falls and fall-related injuries are a major cause of injuries, the purpose of this study was to investigate whether, and to what extent, the stage combat fall technique training could reduce the impact forces of falls from standing. Twenty-six healthy young adults (14 males and 12 females) participated in our study, and were randomly assigned to either a training group or non-training (control) group. Both groups completed a pre-intervention and a post-intervention fall testing session, separated by two weeks, in which they performed naturalistic falls. The training group performed identical pre-intervention fall testing as the control group, and was then required to receive four 1-hour training sessions in the course of two weeks, led by a certified stage combat fall technique training instructor. The training group then completed a post-intervention fall testing session where they performed naturalistic falls and also falls using the fall technique they learned. Falls were induced in both forward and backward directions using a tether-release protocol. Differences between control and training groups at pre-training, and group differences in the change in dependent measures with training, were examined using Mann-Whitney U tests. The results showed that, following stage-combat fall training, the training group exhibited 32% and 35% reduction in median impact forces for forward and backward falls respectively, while the control group exhibited 5% and 2% reductions (p = 0.002 and <0.001). In addition, the training group showed shorter backward fall duration as well as longer impact time, larger impulse, and longer or larger center-of-pressure based measures for both directions of falling than the control group. However, training was not associated with reduced impact force during the naturalistic falls of the training group. To our knowledge, this was the first study to investigate the stage combat fall technique training and demonstrate its effectiveness as an intervention to reduce impact forces of falls, thereby exploring the potential to reduce the number of fall-related injuries. While these falls were induced from standing, whether these results would transfer to an unanticipated fall while walking due to a slip/trip remain to be explored. / Master of Science / As falls and fall-related injuries are a major cause of injuries, the purpose of this study was to investigate whether, and to what extent, the stage combat fall technique training could reduce the impact forces of falls from standing. Twenty-six healthy young adults (14 males and 12 females) participated in our study, and were randomly assigned to either a training group or non-training (control) group. Both groups completed a pre-intervention and a post-intervention fall testing session, separated by two weeks, in which they performed naturalistic falls. The training group was required to receive four 1-hour training sessions in the two-week intervention period, led by a certified stage combat fall technique training instructor. The training group then completed a post-intervention fall testing session where they performed naturalistic falls and also falls using the fall technique they learned. The results showed that, following stage-combat fall training, the training group exhibited nearly a 1/3rd reduction in impact forces for both forward and backward falls, while the control group only exhibited 5% and 2% reductions respectively. Our analysis also showed that the training group achieved this reduction in impact force by increasing the impact time and spreading out their bodies more, to distribute the impact over a larger area. To our knowledge, this was the first study to investigate the stage combat fall technique training and demonstrate its effectiveness as an intervention to reduce impact forces of falls, thereby exploring the potential to reduce the number of fall-related injuries.

The radio spectrum dependent applications are facing a huge scarcity of the resource. To address this issue, future wireless systems require new wireless network architectures and new approaches to spectrum management. Spectrum sharing has emerged as a promising solution to address the radio frequency (RF) spectrum bottleneck. Although spectrum sharing is intended to provide flexible use of the spectrum, the architecture of the existing approaches, such as TV White Space [1] and Citizen Broadband Radio Services (CBRS) [2], have a relatively fixed sharing framework. This fixed structure limits the applicability of the architecture to other bands where the relationship between various new users and different types of legacy users co-exist. Specifically, an important aspect of sharing that has not been explored enough is the cooperation between the resource owner and the opportunistic user. Also in a shared spectrum system, the users do not have any information about the availability and duration of the available spectrum opportunities. This lack of understanding about the shared spectrum leads the research community to explore a number of core spectrum sharing tasks, such as opportunity detection, dynamic opportunity scheduling, and interference protection for the primary users, etc. This report proposes a Primary-Secondary Cooperation Framework to provide flexibility to all the involved parties in terms of choosing the level of cooperation that allow them to satisfy different objective priorities. The cooperation framework allows exchange of a probabilistic assurance: Spectrum Opportunity Duration Assurance (SODA) between the primary and secondary operations to improve the overall spectrum sharing experience for both the parties. This capability will give the spectrum sharing architectures new flexibility to handle evolutions in technologies, regulations, and the requirements of new bands being transitioned from fixed to share usage. In this dissertation we first look into the regulatory aspect of spectrum sharing. We analyze the Federal Communications Commission's (FCC) initiatives with regards to the commercial use of the 150 MHz spectrum block in the 3.5 GHz band. This analysis results into a Spectrum Access System (SAS) architecture and list of required functionalities. Then we address the nature of primary-secondary cooperation in spectrum sharing and propose to generate probabilistic assurances for spectrum opportunities. We use the generated assurance to observe the impact of cooperation from the perspective of spectrum sharing system management. We propose to incorporate primary user cooperation in the auctioning and resource allocation procedures to manage spectrum opportunities. We also analyze the improvement in spectrum sharing experience from the perspective of the primary and secondary users as a result of cooperation. We propose interference avoidance schemes that involve cooperation to improve the achievable quality of service. Primary-secondary cooperation has the potential to significantly influence the mechanism and outcomes of the spectrum sharing systems. Both the primary and secondary operations can benefit from cooperation in a sharing scenario. Based on the priorities of the primary and secondary operations, the users may decide on the level of cooperation that they are willing to participate. Also access to information about the availability and usability of the spectrum opportunity will result in efficient spectrum opportunity management and improved sharing performance for both the primary and secondary users. Thus offering assurances about the availability and duration of spectrum opportunity through primary-secondary cooperation will significantly improve the overall spectrum sharing experience. The research reported in this dissertation is expected to provide a fundamental analytical framework for characterizing and quantifying the implications of primary-secondary cooperation in a spectrum sharing context. It analyzes the technical challenges in modeling different level of cooperation and their impact on the spectrum sharing experience. We hope that this dissertation will establish the fundamentals of the spectrum sharing to allow the involved parties to participate in sharing mechanisms that is suitable to their objective priorities. / PHD

Yes / We adopt a resource dependence approach to explain the effect of state participation on the dissolution of international joint ventures (IJVs). While resource dependence theory has been used to explain the formation of IJVs, we propose an extension of the theory to explain their dissolution. We do so by highlighting the match between foreign firms’ resource needs (resource hierarchy) and the resource provision roles of state-controlled versus private local partners (resource profiles). We further argue that the effect of state participation on the dissolution of IJVs is moderated by foreign firms’ host country experience and IJV age. We test our hypotheses by using data on 623 IJVs in China. Our results show that state participation reduces the risk of IJV dissolution and that the strength of this effect differs depending on the type of state-controlled actor that is involved in an IJV. We also find that host country experience and IJV age moderate the effect of state participation on IJV dissolution. These findings enhance our understanding of IJV dissolution and contribute to the development of resource dependence theory.

Power electronics is inevitably concerned with the processing of variable speed power generations such as in wind turbines, aircraft systems and naval on-board ship systems. The nature of these types of energy is distinct in that their frequency and power vary depending on the speed of the prime-mover. To make use of the variable speed energy, a power processing scheme which transforms the variable speed energy into a constant frequency power is required. There are measures such as mechanical and electrical links for such purposes. Electrical link systems are chosen in this study due to their fast responses and high reliabilities. The power conversion stage may be a dc link with a line-commutated converter, a dc link with a self-commutated inverter, or a cycloconverter. The line-commutated converter and cycloconverter power stages require a fixed frequency supply for operation whereas the self-commutated inverter is capable of stand-alone operation, thus making it attractive. Two cases of variable speed power generation using a permanent magnet synchronous machine (hereafter referred to as PMSM) and a switched reluctance machine (hereafter referred to as SRM) were studied in this dissertation. The possible use of PMSMs has been proved by the good correlation between the experimental results and the theoretically predicted results. Three different control strategies have been proposed, implemented in hardware, and experimentally verified. The efficiency of the VSCF power conversion with a self commutated converter were comparable to the one using a line-commutated converter. A novel converter topology with no dc link capacitor has been proposed for the application of SRMs to the VSCF power conversion. The proposed topology directly links the constant frequency ac source to the SRM. This feature enhances the reliability of the power conversion scheme and reduces the weight and volume of the system. The correlation between the theoretical and experimental results of some key issues showed the feasibility of the proposed VSCF power conversion scheme. In the course of the study, one stage ac to dc power conversion with a compact transformer was required for dc loads. However, phase-controlled ac to dc conversion has the disadvantages of low power factor and harmonic pollution on the utility side, particularly in the case where dc voltage regulation is required. Therefore, a novel single phase rectifier for dc load which provides ohmic isolation with a high frequency transformer is extensively investigated. The proposed scheme had a wide output variation on dc output while maintaining unity power factor and sinusoidal current in the ac input side. Three control strategies for the operation of the converter were proposed and verified experimentally. The harmonic spectra on ac and dc sides are analytically derived and experimentally proved under some load conditions. / Ph. D.

Yes / We investigated the steepened dynamic action potential duration (APD) restitution of rats with pulmonary artery hypertension (PAH) and right ventricular (RV) failure and tested whether the observed APD restitution properties were responsible for negative mechanical restitution in these myocytes. PAH and RV failure were provoked in male Wistar rats by a single injection of monocrotaline (MCT) and compared with saline-injected animals (CON). Action potentials were recorded from isolated RV myocytes at stimulation frequencies between 1 and 9Hz. Action potential waveforms recorded at 1Hz were used as voltage clamp profiles (action potential clamp) at stimulation frequencies between 1 and 7Hz to evoke rate-dependent currents. Voltage clamp profiles mimicking typical CON and MCT APD restitution were applied and cell shortening simultaneously monitored. Compared with CON myocytes, MCT myocytes were hypertrophied; had less polarized diastolic membrane potentials; had action potentials that were triggered by decreased positive current density and shortened by decreased negative current density; APD was longer and APD restitution steeper. APD90 restitution was unchanged by exposure to the late Na+-channel blocker (5μM) ranolazine or the intracellular Ca2+ buffer BAPTA. Under AP clamp, stimulation frequency-dependent inward currents were smaller inMCTmyocytes and were abolished by BAPTA. In MCT myocytes, increasing stimulation frequency decreased contraction amplitude when depolarization duration was shortened, to mimic APD restitution, but not when depolarization duration was maintained. We present new evidence that the membrane potential of PAH myocytes is less stable than normal myocytes, being more easily perturbed by external currents. These observations can explain increased susceptibility to arrhythmias. We also present novel evidence that negative APD restitution is at least in part responsible for the negative mechanical restitution in PAH myocytes. Thus, our study links electrical restitution remodeling to a defining mechanical characteristic of heart failure, the reduced ability to respond to an increase in demand.

No / Evaluation of drug candidates in in-vitro assays of action potential duration (APD) is one component of preclinical safety assessment. Current assays are limited by technically-demanding, time-consuming electrophysiological methods. This study aimed to assess whether a voltage-sensitive dye-based assay could be used instead. Methods Optical APs were recorded using di-4-ANEPPS in electrically field stimulated Beagle left ventricular midmyocardial myocytes (LVMMs). Pharmacological properties of di-4-ANEPPS on the main cardiac ion channels that shape the ventricular AP were investigated using IonWorks™ and conventional electrophysiology. Effects of 9 reference drugs (dofetilide, E4031, d-sotalol, ATXII, cisapride, terfenadine, alfuzosin, diltiazem and pinacidil) with known APD-modulating effects were assessed on optically measured APD at 1 Hz. Results Under optimum conditions, 0.1 μM di-4-ANEPPS could be used to monitor APs paced at 1 Hz during nine, 5 s exposures without altering APD. di-4-ANEPPS had no effect on either hIERG, hINa, hIKs and hIto currents in transfected CHO cells (up to 10 µM) or ICa,L current in LVMMs (at 16 µM). di-4-ANEPPS had no effect on APs recorded with microelectrodes at 1 or 0.5 Hz over a period of 30 min di-4-ANEPPS displayed the sensitivity to record changes in optically measured APD in response to altered pacing frequencies and sequential vehicle additions did not affect the optically measured APD. APD data obtained with 9 reference drugs were as expected except (i) d-sotalol-induced increases in duration were smaller than those caused by other IKr blockers and (ii) increases in APD were not detected using low concentrations of terfenadine. Discussion Early in drug discovery, the di-4-ANEPPS-based method can reliably be used to assess drug effects on APD as part of a cardiac risk assessment strategy.

The present study is the first to examine the effect of first versus second language (L1 versus L2) speech production on specific temporal parameters of speech in bilingual speakers with neurogenic speech disorders. Three persons with apraxia of speech (AOS), three with phonemic paraphasia (PP) and five normal speaking participants were included as subjects in the study. Subjects were required to read phonemically similar L1 and L2 target utterances in a carrier phrase, five times each, at a normal and fast speaking rate, respectively. This rendered four speaking contexts that included speech production in L1 at either a normal (L1NR) or fast speaking rate (L1FR) and speech production in L2 at either a normal (L2NR) or fast speaking rate (L2FR). Acoustic analysis of on-target productions involved measurement of utterance onset duration, vowel duration, utterance duration and voice onset time. Results revealed that in normal speakers, speech production in L2 results in greater token-to-token variability than in L1. However, token-to-token variability in the experimental subjects did not tend to increase whilst speaking in L2, most probably because these subjects generally decreased their speaking rate in this context, resulting in more consistent production. The subjects with AOS and PP seemed to be influenced by the increased processing demands of speaking in L2 to a greater extent than the normal speakers, in that they more frequently experienced difficulty with durational adjustments (decreasing duration in the fast speaking rate) in L2 than in L1. Furthermore, the subjects with AOS or PP also exhibited a greater extent of durational adjustment in L1 than in L2. The durations of most of the subjects with either AOS or PP tended to differ from those of the normal group to a greater extent in L2FR that was hypothesized to be the most demanding speaking context for these subjects. The longer than normal durations and greater than normal token-to-token variability in the subjects with either AOS or PP imply the presence of a motor control deficit. The extent of the motor control deficit appears to be more severe in AOS than in PP as is evident from the finding that the subjects with AOS generally exhibited longer durations and greater token-to-token variability than the subjects with PP. The pattern of breakdown in respect of different parameters and utterance groups also differed between subjects with AOS and PP. The nature of the disorder in AOS and PP thus appears to be both quantitatively and qualitatively different. Regarding measurement of the different temporal parameters, voice onset time appears to be less subject to the influence of L2 than the other measured temporal parameters. The results of this study imply that bilingual AOS is as much a reality as bilingual aphasia. Furthermore, the results underscore the importance of taking contextual factors, specifically L1 versus L2, into account when compiling assessment and treatment procedures for persons with either AOS or PP, since speech production in L2 appears to be motorically more difficult than in L1 for persons with neurogenic involvement. The significance of the results is discussed with reference to the influence of speech production in L2 on temporal control and the underlying nature of AOS and PP with regard to theories of speech sensorimotor control. Copyright / Dissertation (DPhil (Communication Pathology))--University of Pretoria, 2004. / Speech-Language Pathology and Audiology / unrestricted