Aerospace medicine and biology: A continuing bibliography with indexes (supplement 333)

This bibliography lists 122 reports, articles and other documents introduced into the NASA Scientific and Technical Information System during January, 1990. Subject coverage includes: aerospace medicine and psychology, life support systems and controlled environments, safety equipment, exobiology and extraterrestrial life, and flight crew behavior and performance

High Fidelity Bioelectric Modelling of the Implanted Cochlea

Cochlear implants are medical devices that can restore sound perception in individuals with sensorineural hearing loss (SHL). Since their inception, improvements in performance have largely been driven by advances in signal processing, but progress has plateaued for almost a decade. This suggests that there is a bottleneck at the electrode-tissue interface, which is responsible for enacting the biophysical changes that govern neuronal recruitment. Understanding this interface is difficult because the cochlea is small, intricate, and difficult to access. As such, researchers have turned to modelling techniques to provide new insights. The state-of-the-art involves calculating the electric field using a volume conduction model of the implanted cochlea and coupling it with a neural excitation model to predict the response. However, many models are unable to predict patient outcomes consistently. This thesis aims to improve the reliability of these models by creating high fidelity reconstructions of the inner ear and critically assessing the validity of the underlying and hitherto untested assumptions. Regarding boundary conditions, the evidence suggests that the unmodelled monopolar return path should be accounted for, perhaps by applying a voltage offset at a boundary surface. Regarding vasculature, the models show that large modiolar vessels like the vein of the scala tympani have a strong local effect near the stimulating electrode. Finally, it appears that the oft-cited quasi-static assumption is not valid due to the high permittivity of neural tissue. It is hoped that the study improves the trustworthiness of all bioelectric models of the cochlea, either by validating the claims of existing models, or by prompting improvements in future work. Developing our understanding of the underlying physics will pave the way for advancing future electrode array designs as well as patient-specific simulations, ultimately improving the quality of life for those with SHL

Aerospace medicine and biology: A continuing bibliography with indexes (supplement 349)

This bibliography lists 149 reports, articles and other documents introduced into the NASA Scientific and Technical Information System during April, 1991. Subject coverage includes: aerospace medicine and psychology, life support systems and controlled environments, safety equipment, exobiology and extraterrestrial life, and flight crew behavior and performance

Advances in Sensors and Sensing for Technical Condition Assessment and NDT

The adequate assessment of key apparatus conditions is a hot topic in all branches of industry. Various online and offline diagnostic methods are widely applied to provide early detections of any abnormality in exploitation. Furthermore, different sensors may also be applied to capture selected physical quantities that may be used to indicate the type of potential fault. The essential steps of the signal analysis regarding the technical condition assessment process may be listed as: signal measurement (using relevant sensors), processing, modelling, and classification. In the Special Issue entitled “Advances in Sensors and Sensing for Technical Condition Assessment and NDT”, we present the latest research in various areas of technology

Radio wave imaging using Ultra-Wide Band Spectrum Antennas for Near-Field Applications. Design, Development, and Measurements of Ultra-Wideband Antenna for Microwave Near-Field Imaging Applications by applying Optimisation Algorithms

The emergence of Ultra-wideband (UWB) technology application has yielded tremendous and vital impacts in the field of microwave wireless communications. These applications include military radar imaging, security screening, and tumour detection, especially for early detection of breast cancer. These indicators have stimulated and inspired many researchers to make the best use of this promising technology. UWB technology challenges such as antenna design, the problem of imaging reconstruction techniques, challenges of severe signal attenuation and dispersion in high loss material. Others are lengthy computational time demand and large computer memory requirements are prevalent constraints that need to be tackled especially in a large scale and complex computational electromagnetic analysis. In this regard, it is necessary to find out recently developed optimisation techniques that can provide solutions to these problems. In this thesis, designing, optimisation, development, measurement, and analysis of UWB antennas for near-field microwave imaging applications are considered. This technology emulates the same concept of surface penetrating radar operating in various forms of the UWB spectrum. The initial design of UWB monopole antennas, including T-slots, rectangular slots, and hexagonal slots on a circular radiating patch, was explicitly implemented for medical imaging applications to cover the UWB frequency ranging from 3.1 GHz to 10.6 GHz. Based on this concept, a new bow-tie and Vivaldi UWB antennas were designed for a through-the-wall imaging application. The new antennas were designed to cover a spectrum on a lower frequency ranging from 1 GHz - 4 GHz to ease the high wall losses that will be encountered when using a higher frequency range and to guarantee deeper penetration of the electromagnetic wave. Finally, both simulated and calculated results of the designed, optimised antennas indicate excellent agreement with improved performance in terms of return loss, gain, radiation pattern, and fidelity over the entire UWB frequency. These breakthroughs provided reduced computational time and computer memory requirement for useful, efficient, reliable, and compact sensors for imaging applications, including security and breast cancer detection, thereby saving more lives.Tertiary Education Trust Fund (TET Fund) Supported by the Nigerian Defence Academy (NDA

Aerospace medicine and biology: A continuing bibliography with indexes (supplement 373)

This bibliography lists 206 reports, articles and other documents introduced into the NASA Scientific and Technical Information System during Feb. 1993. Subject coverage includes: aerospace medicine and physiology, pharmacology, toxicology, environmental effect, life support systems and man/system technology, protective clothing, exobiology and extraterrestrial life, planetary biology, and flight crew behavior and performance

Early Disease Detection by Extracting Features of Biomedical Signals

Elderly people face a lot of health problems in day to day life due to old age and so many reasons. Therefore a regular health check-up is needed for them which is much more expensive and cannot be afforded by many people. Again the diagnosis is much more complicated to understand and in many cases there is a chance of mistreatment. There is another chance of delay in the detection of disease and late treatment causing risk in their lives. So, the disease should be detected in the early stage for lower cost and lower risk in life. The present work is related to the different physiological parameters of a human being that are to be measured to accurately diagnose the related disease. Though there are numerous physiological parameters, this work emphasizes on some of the most common physiological parameters such as blood pressure, heart rate and ECG which are of primary importance to elderly people. Accurate measurement and analysis of these parameters can lead to diagnose of several lethal disease. In this work, the method of measurement and analysis of these physiological parameters are described. The simulation, processing and analyses of these signals are also done in the work. The prime objective of the research work is to analyze and extract the features of ECG signal and blood pressure signal for early diagnosis of life threatening diseases

Engineering mechanobiology: the bacterial exclusively-mechanosensitive ion channel MscL as a future tool for neuronal stimulation technology

The development of novel approaches to stimulate neuronal circuits is crucial to understand the physiology of neuronal networks, and to provide new strategies to treat neurological disorders. Nowadays, chemical, electrical or optical approaches are the main exploited strategies to interrogate and dissect neuronal circuit functions. However, although all these methods have contributed to achieve important insights into neuroscience research field, they all present relevant limitations for their use in in-vivo studies or clinical applications. For example, while chemical stimulation does not require invasive surgical procedures, it is difficult to control the pharmacokinetics and the spatial selectivity of the stimulus; electrical stimulation provides high temporal bandwidth, but it has low spatial resolution and it requires implantation of electrodes; optical stimulation provides subcellular resolution but the low depth penetration in dense tissue still requires the invasive insertion of stimulating probes. Due to all these drawbacks, there is still a strong need to develop new stimulation strategies to remotely activate neuronal circuits as deep as possible. The development of remote stimulation techniques would allow the combination of functional and behavioral studies, and the design of novel and minimally invasive prosthetic approaches. Alternative approaches to circumvent surgical implantation of probes include transcranial electrical, thermal, magnetic, and ultrasound stimulation. Among v these methods, the use of magnetic and ultrasound (US) fields represents the most promising vector to remotely convey information to the brain tissue. Both magnetic and low-intensity US fields provide an efficient mean for delicate and reversible alteration of cells and tissues through the generation of local mechanical perturbations. In this regard, advances in the mechanobiology research field have led to the discovery, design and engineering of cellular transduction pathways to perform stimulation of cellular activity. Furthermore, the use of US pressure fields is attracting considerable interest due to its potential for the development of miniaturized, portable and implantation-free US stimulation devices. The purpose of my PhD research activity was the establishment of a novel neuronal stimulation paradigm adding a cellular selectivity to the US stimulation technology through the selective mechano-sensitization of neuronal cells, in analogy to the well-established optogenetic approach. In order to achieve the above mentioned goal, we propose the cellular overexpression of mechanosensitive (MS) ion channels, which could then be gated upon the application of an US generated pressure field. Therefore, we selected the bacterial large conductance mechanosensitive ion channel (MscL), an exclusively-MS ion channel, as ideal tool to develop a mechanogenetic approach. Indeed, the MscL with its extensive characterization represents a malleable nano-valve that could be further engineered with respect to channel sensitivity, conductance and gating mechanism, in order to obtain the desired biophysical properties to achieve reliable and efficient remote mechanical stimulation of neuronal activity. In the first part of the work, we report the development of an engineered MscL construct, called eMscL, to induce the heterologous expression of the bacterial protein in rodent primary neuronal cultures. Furthermore, we report the structural and functional characterization of neuronal cells expressing the eMscL channel, at both single-cell and network levels, in order to show that the functional expression of the engineered MscL channel induces an effective vi neuronal sensitization to mechanical stimulation, which does not affect the physiological development of the neuronal itself. In the second part of the work, we report the design and development of a water tank-free ultrasound delivery system integrated to a custom inverted fluorescence microscope, which allows the simultaneous US stimulation and monitoring of neuronal network activity at single resolution. Overall, this work represents the first development of a genetically mechanosensitized neuronal in-vitro model. Moreover, the developed US delivery system provides the platform to perform high-throughput and reliable investigation, testing and calibration of the stimulation protocols. In this respect, we propose, and envisage in the near future, the exploitation of the engineered MscL ion channel as a mature tool for novel neuro-technological applications