722 research outputs found

    The Effect of Attention to Self-Regulation of Speech Sound Productions on Speech Fluency in Oral Reading

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    Purpose: This study ultimately sought to test whether a condition of heightened attention to speech sound production during connected speech serves to trigger increased disfluencies. Disfluencies, or disruptions in the flow of speech, are highly variable in form and location, both within and across individuals and situations. Research to identify conditions that can predictably trigger disfluencies has the potential to provide insight into their elusive nature. A review of related literature covered the cognitive-linguistic theories related to speech fluency and stuttering. This review of previous literature also served as the foundation for why it was proposed that disfluencies would be triggered by heightened self-monitoring attention to how speech sounds are made during connected speech. Methods: Participants included 10 male and 10 female normally fluent adult college students. Their tasks included a baseline oral reading of a 330-word passage, learning of two new speech sounds, followed by an experimental reading of the same passage again. During the experimental reading, target sounds, which were indicated by highlighted locations within the passage, had to be replaced with the newly learned speech sounds. Participants indicated much greater attention was given to how speech sounds were produced during the experimental oral reading than in the baseline oral reading, to support and validate the nature of the task. Results: Disfluencies and oral reading rates were examined using descriptive statistics and analyzed by means of the negative binomial distribution model. Secondary analyses of oral reading rates were conducted with the Wilcoxon’s Signed Rank test. The results revealed that the experimental reading task was associated with a significant increase in Stuttering-Like Disfluency (SLD) and Other Disfluency (OD), and a significant decrease in oral reading rate. Furthermore, SLDs increased significantly more than ODs from the first to the second reading. Discussion: Results supported the hypothesis that disfluency, especially SLD, can be triggered by a condition of increased attention to self-monitoring how speech sounds are produced during connected speech. These findings support theories explaining disfluencies as a symptom of a speaker’s cognitive-linguistic speech planning processes being over-burdened. Implications are raised for specific populations that may be at risk-for more disfluencies: young children learning language, second-language learners, and children in speech therapy. Future research directions are recommended to better understand how to prevent disfluencies in at-risk populations and clarify the enigmatic relationship among attentional processes, phonological production planning, and stuttering

    An inventory control project in a major Danish company using compound renewal demand models

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    We describe the development of a framework to compute the optimal inventory policy for a large spare-parts’ distribution centre operation in the RA division of the Danfoss Group in Denmark. The RA division distributes spare parts worldwide for cooling and A/C systems. The warehouse logistics operation is highly automated. However, the procedures for estimating demands and the policies for the inventory control system that were in use at the beginning of the project did not fully match the sophisticated technological standard of the physical system. During the initial phase of the project development we focused on the fitting of suitable demand distributions for spare parts and on the estimation of demand parameters. Demand distributions were chosen from a class of compound renewal distributions. In the next phase, we designed models and algorithmic procedures for determining suitable inventory control variables based on the fitted demand distributions and a service level requirement stated in terms of an order fill rate. Finally, we validated the results of our models against the procedures that had been in use in the company. It was concluded that the new procedures were considerably more consistent with the actual demand processes and with the stated objectives for the distribution centre. We also initiated the implementation and integration of the new procedures into the company’s inventory management systemBase-stock policy; compound distribution; fill rate; inventory control; logistics; stochastic processes

    When Less Can Be More: Dual Task Effects in Stuttering and Fluent Adults

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    The present study tested the counterintuitive hypothesis that engaging cognitive resources in a secondary task while speaking could benefit aspects of speech production. Effects of dual task conditions on speech fluency, rate, and error patterns were examined in stuttering and fluent speakers based on specific predictions derived from three related theoretical frameworks. Twenty fluent adults and 19 adults with confirmed diagnoses of stuttering participated in the study. All participants completed two baseline tasks: (1) a continuous speaking task in which spontaneous speech was produced in response to given prompts; and (2) a working memory (WM) task involving manipulations of WM domain, WM load, and inter-stimulus interval (ISI). In the dual task portion of the experiment, participants simultaneously performed the speaking task with each unique combination of WM conditions. Resulting performance patterns were examined based on speech-related measures (fluency, rate, errors) and WM accuracy in each speaker group. Contrary to predicted outcomes, both groups showed comparable decrements in secondary task performance as well as comparable fluency benefits as a result of dual task conditions. This effect was specific to atypical forms of disfluency and was similar across all manipulations of the WM task. Changes in fluency were accompanied by reductions in speaking rate, but not by corresponding changes in overt speech errors. Overall, findings suggest that WM contributes to disfluencies regardless of stuttering status and that suppressing these resources enhances speech fluency, possibly by inducing more implicit or automatic modes of movement during speech production. Further research is needed to more precisely identify the cognitive mechanism involved in this effect, clarify the nature of this association, and determine whether and how these findings can inform clinical intervention

    The Impact of Anthropologically Motivated Human Social Networks on the Transmission Dynamics of Infectious Disease

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    abstract: Understanding the consequences of changes in social networks is an important an- thropological research goal. This dissertation looks at the role of data-driven social networks on infectious disease transmission and evolution. The dissertation has two projects. The first project is an examination of the effects of the superspreading phenomenon, wherein a relatively few individuals are responsible for a dispropor- tionate number of secondary cases, on the patterns of an infectious disease. The second project examines the timing of the initial introduction of tuberculosis (TB) to the human population. The results suggest that TB has a long evolutionary history with hunter-gatherers. Both of these projects demonstrate the consequences of social networks for infectious disease transmission and evolution. The introductory chapter provides a review of social network-based studies in an- thropology and epidemiology. Particular emphasis is paid to the concept and models of superspreading and why to consider it, as this is central to the discussion in chapter 2. The introductory chapter also reviews relevant epidemic mathematical modeling studies. In chapter 2, social networks are connected with superspreading events, followed by an investigation of how social networks can provide greater understanding of in- fectious disease transmission through mathematical models. Using the example of SARS, the research shows how heterogeneity in transmission rate impacts super- spreading which, in turn, can change epidemiological inference on model parameters for an epidemic. Chapter 3 uses a different mathematical model to investigate the evolution of TB in hunter-gatherers. The underlying question is the timing of the introduction of TB to the human population. Chapter 3 finds that TB’s long latent period is consistent with the evolutionary pressure which would be exerted by transmission on a hunter- igatherer social network. Evidence of a long coevolution with humans indicates an early introduction of TB to the human population. Both of the projects in this dissertation are demonstrations of the impact of var- ious characteristics and types of social networks on infectious disease transmission dynamics. The projects together force epidemiologists to think about networks and their context in nontraditional ways.Dissertation/ThesisDoctoral Dissertation Anthropology 201

    Statistical modelling of Massively Parallel Sequencing data in forensic genetics

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    On the evolution of microbes: the evolution of genomes with respect to RNA folding

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    We hypothesized that the stringency by which RNA folds (summarized in our analysis by the predicted folding free energy (FFE)) may be under selective pressure, presumably due to its role in (reverse) transcription and translation, and its potential effect on the RNA degradation rate. For bacteria, the RNA folding will depend on the physical properties of their environment. For viruses, this balance needs to be reached for every host the virus is successfully replicated in, and may play a critical role in adapting to new hosts. In the influenza A virus, we have shown that the FFE of its polymerase genes is evolving through time from lower to higher values, every time an avian segment jumps into humans. We postulated that this may be related to the difference in body temperature between humans and birds, as generally the genes isolated from avian sources have significantly lower FFE than the human isolates. Furthermore, we can use the FFE and amino acid sequence of the influenza A virus, to classify whether a given virus is similar to others that can jump to and successfully infect human hosts. In bacteria, we have shown that, consistent with previous studies of GC content, tRNA FFE is linearly correlated with growth temperature; while mRNA FFE is not. Regardless, we showed that the growth conditions are related to mRNA FFE distributions and function. Furthermore, there is a relation between mRNA FFE and half-life. Finally, we showed that gene expression can be predicted from RNA structure and sequence properties. In studying RNA folding in both viruses and bacteria, we were able to view the possible association between FFE and environment in two ways: the number of bacterial genomes sequenced allows us to get a sense of what RNA structures and folding energies are required for the bacteria to inhabit a wide variety of environments- everything from the human body to colonizing black smokers on the ocean floor; while the number of influenza A genomes sequenced allows us to determine how the RNA structures change over time. By using both sets of information, we can get a clearer picture of both the importance of RNA structure, and how RNA structure and folding energy evolve as the host environment changes

    Reliability assessment of null allele detection: inconsistencies between and within different methods

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    Microsatellite loci are widely used in population genetic studies, but the presence of null alleles may lead to biased results. Here we assessed five methods that indirectly detect null alleles, and found large inconsistencies among them. Our analysis was based on 20 microsatellite loci genotyped in a natural population of Microtus oeconomus sampled during 8 years, together with 1200 simulated populations without null alleles, but experiencing bottlenecks of varying duration and intensity, and 120 simulated populations with known null alleles. In the natural population, 29% of positive results were consistent between the methods in pairwise comparisons, and in the simulated dataset this proportion was 14%. The positive results were also inconsistent between different years in the natural population. In the null-allele-free simulated dataset, the number of false positives increased with increased bottleneck intensity and duration. We also found a low concordance in null allele detection between the original simulated populations and their 20% random subsets. In the populations simulated to include null alleles, between 22% and 42% of true null alleles remained undetected, which highlighted that detection errors are not restricted to false positives. None of the evaluated methods clearly outperformed the others when both false positive and false negative rates were considered. Accepting only the positive results consistent between at least two methods should considerably reduce the false positive rate, but this approach may increase the false negative rate. Our study demonstrates the need for novel null allele detection methods that could be reliably applied to natural population
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