Collected works related to the development of the modern cochlear implant

University of Technology Sydney. Faculty of Engineering and Information Technology.This thesis for a higher doctorate in engineering at the University of Technology, Sydney (UTS) presents collected works related to the development of the modern cochlear implant, a prosthesis that restores useful hearing for deaf or severely hearing impaired persons. The emphasis is on the engineering aspects of the development, and the principal work for this thesis is the book ‘Better Hearing with Cochlear Implants: Studies at the Research Triangle Institute’, which is a major engineering treatise. In addition, ten further publications are included that also describe engineering aspects of the development. This bounded thesis includes the ten further publications, an acknowledgments section, a published review of the book, a one-page biographical sketch for the author, and the author’s full CV. The book is available separately at the UTS Library or from the publisher, Plural Publishing, Inc., of San Diego, CA, USA

Correlation functions quantify super-resolution images and estimate apparent clustering due to over-counting

We present an analytical method to quantify clustering in super-resolution localization images of static surfaces in two dimensions. The method also describes how over-counting of labeled molecules contributes to apparent self-clustering and how the effective lateral resolution of an image can be determined. This treatment applies to clustering of proteins and lipids in membranes, where there is significant interest in using super-resolution localization techniques to probe membrane heterogeneity. When images are quantified using pair correlation functions, the magnitude of apparent clustering due to over-counting will vary inversely with the surface density of labeled molecules and does not depend on the number of times an average molecule is counted. Over-counting does not yield apparent co-clustering in double label experiments when pair cross-correlation functions are measured. We apply our analytical method to quantify the distribution of the IgE receptor (Fc{\epsilon}RI) on the plasma membranes of chemically fixed RBL-2H3 mast cells from images acquired using stochastic optical reconstruction microscopy (STORM) and scanning electron microscopy (SEM). We find that apparent clustering of labeled IgE bound to Fc{\epsilon}RI detected with both methods arises from over-counting of individual complexes. Thus our results indicate that these receptors are randomly distributed within the resolution and sensitivity limits of these experiments.Comment: 22 pages, 5 figure

Harnessing the power of artificial intelligence to transform hearing healthcare and research

The advances in artificial intelligence that are transforming many fields have yet to make an impact in hearing. Hearing healthcare continues to rely on a labour-intensive service model that fails to provide access to the majority of those in need, while hearing research suffers from a lack of computational tools with the capacity to match the complexities of auditory processing. This Perspective is a call for the artificial intelligence and hearing communities to come together to bring about a technological revolution in hearing. We describe opportunities for rapid clinical impact through the application of existing technologies and propose directions for the development of new technologies to create true artificial auditory systems. There is an urgent need to push hearing towards a future in which artificial intelligence provides critical support for the testing of hypotheses, the development of therapies and the effective delivery of care worldwide

A comparison of two astronomical tuning approaches for the Oligocene-Miocene Transition from Pacific Ocean Site U1334 and implications for the carbon cycle

Astronomical tuning of sediment sequences requires both unambiguous cycle-pattern recognition in climate proxy records and astronomical solutions, and independent information about the phase relationship between these two. Here we present two astronomically tuned age models for the Oligocene-Miocene Transition (OMT) from Integrated Ocean Drilling Program Site U1334 (equatorial Pacific Ocean) to assess the effect tuning approaches have on astronomically calibrated ages and the geologic time scale. These age models are based on different phase-assumptions between climate proxy records and eccentricity: the first age model is based on an inverse and in-phase assumption of CaCO3 weight (wt %) to Earth's orbital eccentricity, the second age model is based on an inverse and in-phase assumption of benthic foraminifer stable carbon isotope ratios (δ13C) to eccentricity. The phase-assumptions that underpin these age models represent two end-members on the range of possible tuning options. To independently test which tuned age model and tuning assumptions are correct, we assign their ages to magnetostratigraphic reversals identified in anomaly profiles. Subsequently we compute tectonic plate-pair spreading rates based on the tuned ages. These alternative spreading rate histories indicate that the CaCO3 tuned age model is most consistent with a conservative assumption of constant spreading rates. The CaCO3 tuned age model thus provides robust ages and durations for polarity chrons C6Bn.1n–C6Cn.1r, which are not based on astronomical tuning in the latest iteration of the Geologic Time Scale. Furthermore, it provides independent evidence that the relatively large (several 10,000 years) time lags documented in the benthic foraminiferal isotope records relative to orbital eccentricity, constitute a real feature of the Oligocene-Miocene climate system and carbon cycle. The age constraints from Site U1334 thus provide independent evidence that the delayed responses of the Oligocene-Miocene climate-cryosphere system and carbon cycle resulted from increased nonlinear feedbacks to astronomical forcing

Increasing the frequency of hand washing by healthcare workers does not lead to commensurate reductions in staphylococcal infection in a hospital ward

Hand hygiene is generally considered to be the most important measure that can be applied to prevent the spread of healthcare-associated infection (HAI). Continuous emphasis on this intervention has lead to the widespread opinion that HAI rates can be greatly reduced by increased hand hygiene compliance alone. However, this assumes that the effectiveness of hand hygiene is not constrained by other factors and that improved compliance in excess of a given level, in itself, will result in a commensurate reduction in the incidence of HAI. However, several researchers have found the law of diminishing returns to apply to hand hygiene, with the greatest benefits occurring in the first 20% or so of compliance, and others have demonstrated that poor cohorting of nursing staff profoundly influences the effectiveness of hand hygiene measures. Collectively, these findings raise intriguing questions about the extent to which increasing compliance alone can further reduce rates of HAI. In order to investigate these issues further, we constructed a deterministic Ross-Macdonald model and applied it to a hypothetical general medical ward. In this model the transmission of staphylococcal infection was assumed to occur after contact with the transiently colonized hands of HCWs, who, in turn, acquire contamination only by touching colonized patients. The aim of the study was to evaluate the impact of imperfect hand cleansing on the transmission of staphylococcal infection and to identify, whether there is a limit, above which further hand hygiene compliance is unlikely to be of benefit. The model demonstrated that if transmission is solely via the hands of HCWs, it should, under most circumstances, be possible to prevent outbreaks of staphylococcal infection from occurring at a hand cleansing frequencies <50%, even with imperfect hand hygiene. The analysis also indicated that the relationship between hand cleansing efficacy and frequency is not linear - as efficacy decreases, so the hand cleansing frequency required to ensure R0<1 increases disproportionately. Although our study confirmed hand hygiene to be an effective control measure, it demonstrated that the law of diminishing returns applies, with the greatest benefit derived from the first 20% or so of compliance. Indeed, our analysis suggests that there is little benefit to be accrued from very high levels of hand cleansing and that in most situations compliance >40% should be enough to prevent outbreaks of staphylococcal infection occurring, if transmission is solely via the hands of HCWs. Furthermore we identified a non-linear relationship between hand cleansing efficacy and frequency, suggesting that it is important to maximise the efficacy of the hand cleansing process

T cell lineage choice and differentiation in the absence of the RNase III enzyme dicer

The ribonuclease III enzyme Dicer is essential for the processing of micro-RNAs (miRNAs) and small interfering RNAs (siRNAs) from double-stranded RNA precursors. miRNAs and siRNAs regulate chromatin structure, gene transcription, mRNA stability, and translation in a wide range of organisms. To provide a model system to explore the role of Dicer-generated RNAs in the differentiation of mammalian cells in vivo, we have generated a conditional Dicer allele. Deletion of Dicer at an early stage of T cell development compromised the survival of alphabeta lineage cells, whereas the numbers of gammadelta-expressing thymocytes were not affected. In developing thymocytes, Dicer was not required for the maintenance of transcriptional silencing at pericentromeric satellite sequences (constitutive heterochromatin), the maintenance of DNA methylation and X chromosome inactivation in female cells (facultative heterochromatin), and the stable shutdown of a developmentally regulated gene (developmentally regulated gene silencing). Most remarkably, given that one third of mammalian mRNAs are putative miRNA targets, Dicer seems to be dispensable for CD4/8 lineage commitment, a process in which epigenetic regulation of lineage choice has been well documented. Thus, although Dicer seems to be critical for the development of the early embryo, it may have limited impact on the implementation of some lineage-specific gene expression programs

Alcohol Production as an Adaptive Livelihood Strategy for Women Farmers in Tanzania and Its Potential for Unintended Consequences on Women's Reproductive Health.

Although women occupy a central position in agriculture in many developing countries, they face numerous constraints to achieving their full potential including unequal access to assets and limited decision-making authority. We explore the intersection of agricultural livelihoods, food and economic security, and women's sexual and reproductive health in Iringa Region, Tanzania. Our goal was to understand whether the benefits of supporting women in the agricultural sector might also extend to more distal outcomes, including sexual and reproductive health. Using the Sustainable Livelihoods Framework to guide data collection, we conducted 13 focus group discussions (FGD) with female (n = 11) and male farmers (n = 2) and 20 in-depth interviews with agricultural extension officers (n = 10) and village agro-dealers (n = 10). Despite providing the majority of agricultural labor, women have limited control over land and earned income and have little bargaining power. In response to these constraints, women adopt adaptive livelihood strategies, such as alcohol production, that allow them to retain control over income and support their households. However, women's central role in alcohol production, in concert with the ubiquitous nature of alcohol consumption, places them at risk by enhancing their vulnerability to unsafe or transactional sex. This represents a dangerous confluence of risk for female farmers, in which alcohol plays an important role in income generation and also facilitates high-risk sexual behavior. Alcohol production and consumption has the potential to both directly and indirectly place women at risk for undesirable sexual and reproductive health outcomes. Group formation, better access to finance, and engaging with agricultural extension officers were identified as potential interventions for supporting women farmers and challenging harmful gender norms. In addition, joint, multi-sectoral approaches from health and agriculture and alternative income-generating strategies for women might better address the complexities of achieving safe and sustainable livelihoods for women in this context

Patient-Specific Prosthetic Fingers by Remote Collaboration - A Case Study

The concealment of amputation through prosthesis usage can shield an amputee from social stigma and help improve the emotional healing process especially at the early stages of hand or finger loss. However, the traditional techniques in prosthesis fabrication defy this as the patients need numerous visits to the clinics for measurements, fitting and follow-ups. This paper presents a method for constructing a prosthetic finger through online collaboration with the designer. The main input from the amputee comes from the Computer Tomography (CT) data in the region of the affected and the non-affected fingers. These data are sent over the internet and the prosthesis is constructed using visualization, computer-aided design and manufacturing tools. The finished product is then shipped to the patient. A case study with a single patient having an amputated ring finger at the proximal interphalangeal joint shows that the proposed method has a potential to address the patient's psychosocial concerns and minimize the exposure of the finger loss to the public.Comment: Open Access articl