Tinnitus is a problem that affects a diverse range of people. One common trait amongst people with tinnitus is the presence of hearing loss, which is apparent in over 90% of the cohort. It is postulated that the remainder of people with tinnitus have hidden hearing loss in the form of cochlear synaptopathy. The loss of hearing sensation is thought to cause a reduction in the bottom-up excitatory signals of the auditory pathway leading to a change in the frequency of thalamocortical oscillations known as thalamocortical dysrhythmia (TCD). The downward shift in oscillatory behavior, characteristic of TCD, has been recorded experimentally but the underlying mechanisms responsible for TCD in tinnitus subjects cannot be directly observed. This paper investigates these underlying mechanisms by creating a biologically faithful model of the auditory periphery and thalamocortical network, called the central auditory processing (CAP) model. The proposed model replicates tinnitus related activity in the presence of hearing loss and hidden hearing loss in the form of cochlear synaptopathy. The results of this paper show that, both the bottom-up and top-down changes are required in the auditory system for tinnitus related hyperactivity to coexist with TCD, contrary to the theoretical model for TCD. The CAP model provides a novel modeling approach to account for tinnitus related activity with and without hearing loss. Moreover, the results provide additional clarity to the understanding of TCD and tinnitus and provide direction for future approaches to treating tinnitus.

The purpose of the current paper is to demonstrate the feasibility of a new technique whereby mass flowrates, and hence discharge coefficients can be estimated for a range of pipe discontinuities such as poppet valves, throttles, cylinder ports, and orifices. The requirement to directly measure the mass flowrates using a standard conventional steady flow apparatus has been eliminated. As such, flow characteristics were examined during the transient charging or inflow of air, from atmosphere, through a sharp-edged orifice into a partially evacuated cylinder of known volume. In particular, the current study focused on measuring the transient mass flowrates, pressures, and temperatures of air during an inflow test. Comparison between measured gas pressures and temperatures were made with predicted values from an adiabatic and non-adiabatic zero-dimensional inflow model. Mass flowrates calculated from measured cylinder gas pressure data, without heat transfer correction, were shown to be approximately 20 per cent lower, across the full pressure ratio range, than those measured using the mass flow meter. Iterative trial and error techniques were employed to determine the constant and time varying convective heat transfer coefficients needed to correlate the cumulative mass during inflow with the total mass of air, from initial and final cylinder conditions. Heating the cylinder wall to ensure isothermal conditions resulted in an improved correlation between the measured and estimated mass flowrates.

Extrusion of polymeric materials can be made more efficient by modelling with computational techniques. Material-dependent data obtained through a constitutive equation is required to close the fluid dynamic equations. The paper outlines constitutive equations developed for non-Newtonian behaviour and details the choice that is required to obtain a constitutive equation that encapsulates actual material behaviour. 

Tinnitus is the phantom perception of sound, experienced by 10-15% of the global population. Computational models have been used to investigate the mechanisms underlying the generation of tinnitus-related activity. However, existing computational models have rarely benchmarked the modelled perception of a phantom sound against recorded data relating to a person's perception of tinnitus characteristics; such as pitch or loudness. This paper details the development of two perceptual models of tinnitus. The models are validated using empirical data from people with tinnitus and the models' performance is compared with existing perceptual models of tinnitus pitch. The first model extends existing perceptual models of tinnitus, while the second model utilises an entirely novel approach to modelling tinnitus perception using a Linear Mixed Effects (LME) model. The LME model is also used to model the perceived loudness of the phantom sound which has not been considered in previous models. The LME model creates an accurate model of tinnitus pitch and loudness and shows that both tinnitus-related activity and individual perception of sound are factors in the perception of the phantom sound that characterizes tinnitus.

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