Hearing loss negatively affects the lives of millions of Americans (Lin, Niparko, & Ferrucci, 2011). Amplification can enhance audibility and in turn improve quality of life (Mulrow et al., 1990). Yet it is estimated that only 20% of those who would benefit from amplification in the United States actually utilize it (Chien & Lin, 2012). Discomfort and insufficient value have been cited as reasons for low uptake as well as low motivation, negative attitudes towards hearing aids, and lack self-perceived handicap (McCormack & Fortnum, 2013; Vestergaard-Knudsen et al., 2010). Studies have also attributed the out-of-pocket cost for hearing aids as a substantial barrier (Bainbridge & Ramachandran, 2014; Kochkin, 2000). Cost as a barrier to hearing aid access may be an issue of particular importance in regions with high poverty, as low-income adults are less likely to report hearing aid use (Bainbridge & Ramachandran, 2014). Hearing aids can typically cost about $2,000 each, possibly making them out of reach for individuals living at or below the poverty line. Arizona has one of the highest poverty rates in the United States (Bishaw & Fontenot, 2014). Using US Census data and epidemiologic studies, we estimate that there are approximately 1,145,166 adults over the age of 19 living with significant bilateral or unilateral hearing loss in Arizona. An estimated 204,984 of these individuals are living at or below the federal poverty line (Lin, Naparko, & Ferrucci, 2011; Bishaw & Fontenot, 2014, Muller et al., 2015, US Census). These numbers are particularly alarming, as there are limited resources to support adults with hearing loss in Arizona. The aim of this study was to gather provider perspectives on the accessibility and affordability of hearing healthcare in Arizona. The long-term goal is to develop a state-level initiative to increase hearing aid use among low-income adults. Based on previous research from the Hearing Aid Coalition, we hypothesized that Arizona providers would prefer a state-level plan that mirrors service coverage and reimbursement mechanisms of private insurance (Hearing Aid Coalition, 2004) Audiologists and hearing instrument specialists were recruited via email to participate in focus groups and surveys. Three focus groups were held across the state in Phoenix, Flagstaff and Tucson (n = 26). The survey methodology included open and closed questions and was administered in paper-based and online versions (n = 77). Data were transcribed, coded, and analyzed using descriptive and basic regression analyses. There was wide-ranging participation from providers across the state representing urban and rural practice locations (All 15 counties represented). Data revealed most providers would prefer to see changes in the current state of hearing access for low-income adults. Providers considered a number of factors to be important when developing and implementing changes to existing service delivery. These factors included a centralized entity to distribute referrals across practices and sufficient reimbursement for service providers. Common themes included the need for a balance between quality of care and expense as well as creating a fee-for-service component to invest the patient in the process. Increased philanthropic practice image and fair compensation were cited as the greatest motivations for provider participation. Survey results also indicated that most providers are already doing pro-bono work. This study highlights that providers are willing to participate in state-level initiatives to improve hearing aid access. Ultimately, these results will inform policy makers of provider preferences for mechanisms of service-delivery and reimbursement. This research is a collaborative project funded by the Arizona Commission for the Deaf and the Hard of Hearing.

No description available.

Switched mode, Class-D power amplification allows for high efficiency power amplification of an audio signal. This thesis investigates its application to high power car audio systems where there is a demand for efficient high power amplification. Examination of the present car audio power amplifiers, which comprise a switched mode power supply combined with a linear output stage, has shown that there is significant scope for improvement in efficiency and power density. A novel power stage in which the attributes of a switched-mode power supply and full bridge output stage is presented. It is demonstrated that elimination of the intermedjate DC supply results in an amplifier which has a significantly lower part count, size and cost compared to conventional designs. Two different modulation schemes are explored (PWM and PDM) with a view to finding the most suitable for the new power stage. The theoretical performances of the modulators are verified by practical measurements. The design of high order DeltaSigma modulators is difficult as they show unstable behaviour and an alternative design methodology has been presented to ease this task. The mechanisms which introduce distortion in a practical amplifier are discussed, and for the case of a PWM driven output stage, a new model is presented to predict the effect of dead time on harmonic distortion. This form of distortion is shown to be the dominant cause of open loop non-linearity. The use of feedback is also investigated and yields a factor of 20 improvement in amplifier total harmonic distortion . The design throughout has been supported with practical results and these have illustrated the importance for careful circuit layout in high frequency switching systems.

Using the technology afforded by Winschel et al., cyclen-1, a high affinity, strong complexation agent for 8-hydroxypyrene-1,3,6 trisulfonate and derivatives, a new assay has been developed for fluorescently labeling proteins of interest (POIs). Ligation of the endogenous ligand for nicotinic acetylcholine receptors (nAChRs), acetylcholine, using click chemistry afforded the triazole derivative of an alkynyl-acylcholine (compound 1) with 8-azidopyrene-1,3,6 trisulfonate (compound 2). Liposomes encapsulated with Rhodamine B were used to strengthen the initial fluorophore response of compound 2, using an anchored form of cyclen-1 complex. Using a palmitoyl tail as the lipophilic moiety for liposomal amplification, the subsequent response has a fluorophore ratio of up to 1:1 million, compound 2:Rhodamine B molecules. in vitro assay using compound 2 and cyclen-1 anchored liposomes with HEK-293 cells produced a positive binding response, allowing brightly colored fluorescent images of nAChRs upon the cellular membrane. A control for nAChR binding was performed using a co-culture of HEK-293 and endothelial cell lines. Control experiments show compound 2 and liposomes weak binding endothelial cells, however, this could be do to accumulation from another mechanism, more work is necessary to prove whether or not this is correct.

DNA polymerases play a fundamental role in the transmission and maintenance of genetic information and have become an important in vitro diagnostic and analytical tool. The Loop-mediated isothermal DNA amplification (LAMP) method has major applications for disease and pathogen detection and utilises the unique strand-displacement activity of a small group of thermostable DNA polymerases. The Large (Klenow-like) Fragment of Geobacillus stearothermophilus DNA polymerase I (B.st LF Pol I) currently serves as the enzyme of choice for the majority of these isothermal reactions, with few alternatives commercially available. An increasing need for point-of-care nucleic acid diagnostics is now shifting detection methods away from traditional laboratory based chemistries, such as the polymerase chain reaction (PCR), in favour of faster, and often simpler, isothermal methods. It was recognised that in order to facilitate these rapid isothermal reactions there was a requirement for alternative thermostable, strand-displacing DNA polymerases and this was the basis of this thesis. This thesis reports the successful identification of polymerases from Family A, chosen for their inherent strand-displacement activity, which is essential for the removal of RNA primers of Okazaki fragments during lagging-strand DNA synthesis in vivo. Twelve thermophilic organisms, with growth temperature ranges between 50oC and 80oC, were identified and the genomic DNA extracted. Where DNA sequences were unavailable, a gene-walking technique revealed the polA sequences, enabling the Large Fragment Pol I to be cloned and the recombinant protein over-expressed in Escherichia coli. A three-stage column chromatography purification permitted the characterisation of ten newly identified Pol I enzymes suitable for use in LAMP. Thermodesulfatator indicus (T.in) Pol I proved to be the most interesting enzyme isolated. Demonstrating strong strand-displacement activity and thermostability to 98oC, T.in Pol I is uniquely suitable to a newly termed heat-denaturing LAMP (HD-LAMP) reaction offering many potential advantages over the existing LAMP protocol. The current understanding of strand-displacement activity of Pol I is poorly understood. This thesis recognised the need to identify the exact regions and motifs responsible for this activity of the enzyme, enabling potential enhancements to be made. Enzyme engineering using site-directed mutagenesis and the formation of chimeras confirmed the importance of specific subdomains in strand-separation activity. With this knowledge, a unique Thermus aquaticus (T.aq) Pol I mutant demonstrated sufficient strand-displacement activity to permit its use in LAMP for the first time. The fusion of Cren7, a double-stranded DNA binding protein, to Pol I for use in LAMP is also reported. Although the fusion construct was found to reduce amplification speed, enhancements were observed in the presence of increased salt concentrations and it is suggested here as a means for future enzyme development.

In this master thesis a control strategy for a Human Power Amplifier (HPA) ispresented. An HPA can be described as a machine that amplifies a force exertedby a human operator. The HPA in this thesis can best be described as a mechanicalore with two degrees of freedom.The approach for the control strategy presented here is to look at the controlproblem not directly as a force amplifying problem, but as coordination problembetween the real system and a virtual system, where the virtual system is used asa reference. If the systems are synchronized then desired force amplification willnaturally follow from that.Furthermore is the possibility to implement guidance and obstacle avoidanceon the machine investigated. The guidance is performed by using velocity fields,i.e., vector fields where a vector represents the desired velocity for each point inthe plane. For the obstacle avoidance potential fields are used, where the idea isthat a high potential should repel the machine from restricted areas.

No description available.

Thèse doctorat : Aspects Moléculaires et Cellulaires de la Biologie : Strasbourg 1 : 2006. / Thèse soutenue sur un ensemble de travaux. Titre provenant de l'écran-titre. Bibliogr. 24 p.

published_or_final_version / Microbiology / Master / Master of Medical Sciences

published_or_final_version / Pathology / Master / Master of Medical Sciences