Progressive auditory neuropathy in patients with Leber's hereditary optic neuropathy

Objective: To investigate auditory neural involvement in patients with Leber's hereditary optic neuropathy (LHON).Methods: Auditory assessment was undertaken in two patients with LHON. One was a 45 year old woman with Harding disease (multiple-sclerosis-like illness and positive 11778mtDNA mutation) and mild auditory symptoms, whose auditory function was monitored over five years. The other was a 59 year old man with positive 11778mtDNA mutation, who presented with a long standing progressive bilateral hearing loss, moderate on one side and severe to profound on the other. Standard pure tone audiometry, tympanometry, stapedial reflex threshold measurements, stapedial reflex decay, otoacoustic emissions with olivo-cochlear suppression, auditory brain stem responses, and vestibular function tests were undertaken.Results: Both patients had good cochlear function, as judged by otoacoustic emissions ( intact outer hair cells) and normal stapedial reflexes ( intact inner hair cells). A brain stem lesion was excluded by negative findings on imaging, recordable stapedial reflex thresholds, and, in one of the patients, olivocochlear suppression of otoacoustic emissions. The deterioration of auditory function implied a progressive course in both cases. Vestibular function was unaffected.Conclusions: The findings are consistent with auditory neuropathy - a lesion of the cochlear nerve presenting with abnormal auditory brain stem responses and with normal inner hair cells and the cochlear nucleus (lower brain stem). The association of auditory neuropathy, or any other auditory dysfunction, with LHON has not been recognised previously. Further studies are necessary to establish whether this is a consistent finding

Assessment of Aliphatic Based Soot Inception in Laminar Diffusion Flames

Paper presented at 2018 Canadian Society of Mechanical Engineers International Congress, 27-30 May 2018.Soot models are key components of computation fluid dynamic combustion codes that attempt to prescribe how soot is formed. However, due to the complex nature of soot formation, not all pathways may have been fully characterized. This work investigates numerically the influence that an aliphatic-collision (open-chain hydrocarbon) based soot inception model has on soot formation for coflow ethylene/air and methane/air laminar diffusion flames. In the literature, prediction of the soot volume fraction along the centerline of coflow ethylene flames is lacking in accuracy. Similarly for methane flames, soot formation on the wings are under predicted by many models. A new collision based inception model has been developed for specific aliphatics, and applied using an existing framework for molecular collision, in conjunction with pyrene based inception. The purpose of this model is not to be completely fundamental in nature, but more so a proof of concept in that by using physically realistic values for surface reactivity and collision efficiency, this collision mechanism can account for soot formation deficiencies that exist with just polycyclic aromatic hydrocarbon (PAH) based inception. Using this new model, the peak soot volume fraction along the centerline of an ethylene flame can be increased while the peak soot volume fraction along the wings remains unchanged, showing potential to significantly improve the model’s predicative capability. Applying this model to a methane flame has resulted in an increase in the soot volume fraction in both the centerline and the wings, again improving predictive capability

An application of simulated annealing to the optimum design of reinforced concrete retaining structures

This paper reports on the application of a simulated annealing algorithm to the minimum cost design of reinforced concrete retaining structures. Cantilever retaining walls are investigated, being representative of reinforced concrete retaining structures that are required to resist a combination of earth and hydrostatic loading. To solve such a constrained optimisation problem, a modified simulated annealing algorithm is proposed that avoids the simple rejection of infeasible solutions and improves convergence to a minimum cost. The algorithm was implemented using an object-orientated visual programming language, offering facilities for continual monitoring, assessing and changing of the simulated annealing control parameters. Results show that the simulated annealing can be successfully applied to the minimum cost design of reinforced concrete retaining walls, overcoming the difficulties associated with the practical and realistic assessment of the structural costs and their complex inter-relationship with the imposed constraints on the solution space

Life cycle environmental performance of material specification: a BIM-enhanced comparative assessment

This study aims to evaluate the extent to which building material specification affects life cycle environmental performance, using a building information modelling (BIM)-enhanced life cycle assessment (LCA) methodology. A combination of the BIM-based design and analysis tool Revit Architecture, the energy simulation tool Green Building Studio (GBS) and the LCA tool ATHENA Impact Estimator were used for the assessment. The LCA was carried out on a life case study of a 2100 m2 two-floor primary-school building, as well as a variability analysis, by varying the material specification in terms of whole building materials. The life cycle performance of the buildings was primarily evaluated in terms of its global warming potential (GWP) and health impact. The findings of the study show that irrespective of the materials used, buildings that are based on renewable energy perform better than those based on fossil fuels over their life cycle. In terms of building materials, both environmental and health preferences of buildings congruently range from timber, brick/block and steel to insulated concrete formwork (ICF), in descending order. The study suggests that as buildings become more energy efficient during operational stages, serious attention needs to be given to their embodied impact. The study lays out a methodological framework that could be adopted by industry practitioners in evaluating life cycle environmental impact of different BIM-modelled material options at the building conception stage. This has the tendency to ensure that the highest proportion of life cycle environmentally beneficial material combinations are selected during specification and construction

Design of heat sinks for wearable thermoelectric generators to power personal heating garments: A numerical study

To mitigate climate change attributed to the built environments, there have been tremendous efforts to improve air conditioning systems in the buildings. The possibility of harvesting body heat as a renewable energy source to power a wearable personal heating system is investigated. The aim of this study is to integrate a wearable personal heating system with a thermoelectric generator (TEG) that harvests the body heat which is used to convert it into electricity. Moreover, the interaction between the TEG configuration and power output is studied. The power generation of TEG system is obtained by COMSOL Multiphysics software. The simulation results concluded that all the four proposed heat sink configurations can improve the power output of the wearable TEG at 1.4 m/s and 3m/s compared to that of the reference model. Furthermore, the perforated and trapezium shapes of heat sinks have a significantly better performance in comparison to conventional heat sinks

Clinical value of tone burst vestibular evoked myogenic potentials at threshold in acute and stable Ménière's disease

Introduction: The objectives of this preliminary, prospective, cohort study were to ascertain the characteristics of vestibular evoked myogenic potentials at threshold levels in two groups of Ménière's disease patients – acute and stable – and to identify whether vestibular evoked myogenic potentials can provide any specific, objective information to distinguish acute from stable Ménière's disease. Subjects and methods: The study was based at a tertiary neuro-otology centre. Twenty adult patients who fulfilled the American Academy of Otolaryngology–Head and Neck Surgery1 criteria for Ménière's disease were divided into two groups: 11 patients with acute Ménière's disease and nine patients with stable Ménière's disease. Eighteen healthy adult volunteers served as controls. All subjects underwent vestibular evoked myogenic potential testing with ipsilateral, short tone burst stimuli at 500 Hz, as well as pure tone audiometry. The patients also underwent caloric testing. Results: Vestibular evoked myogenic potentials were present in all controls, and were present in 65 per cent of patients but absent in 35 per cent. The mean absolute threshold (Tvestibular evoked myogenic potential) ± standard deviation in normal controls was 116 ± 7.7 dBSPL; this did not differ statistically from that in patients, nor did it differ between acute and stable Ménière's disease. The p13/n23 latencies at the threshold levels in the normal, acute and stable groups (mean ± standard deviation) were respectively: 15 ± 2.2 ms/23.0 ± 2.5 ms; 15.7 ± 0.9 ms/23.7 ± 0.9 ms; and 15.3 ± 2.0 ms/24.2 ± 1.9 ms. The mean interaural amplitude difference ratio (IAD) ± standard deviation was significantly higher in the stable group compared with the acute group (0.54 ± 0.33 vs −0.15 ± 0.22; p = 0.007) and with the controls (0.54 ± 0.33 vs 0.1 ± 0.22; p = 0.05). Conclusions: The parameter that best differentiated acute from stable Ménière's disease at threshold was the interaural amplitude difference ratio. Therefore, this parameter may be used to monitor the clinical course of Ménière's disease

A review on recent developments of thermoelectric materials for room-temperature applications

Wearable thermoelectric generators (TEGs) emerge as a viable renewable energy source, which directly convert the heat dissipated from human skin into electricity. Extensive reviews have been conducted on the efficiency of thermoelectric materials (TE) as the dominant element of TEGs. TE materials are categorised as inorganic, organic, and hybrid. Each of these reviews focused on either a specific type of TE materials, or on a certain specification (i.e. flexibility) of them. However, less attention has been paid to comprehensively review all these types without taking into account a certain specification. Therefore, the purpose of this paper is to summarize the progress and current state-of-the-art research on the three types of TE materials respecting their TE properties and efficiency at 300K, which is the operating temperature of wearable TEGs. Concerning the inorganic TE materials, the results show that Bi0.4-xSb1.6+xTe3 and Bi2Te2.7Se0.3 are the most optimal TE materials, which exhibit the greatest efficiencies at room temperature. In addition, it is remarkably more efficient to replace polymer based TE composites with carbon based TE composites in the organic and the hybrid types. In total, this comprehensive review paves the way for researchers to find out the most suitable TE materials at room temperatures

Optimization of a wearable thermoelectric generator encapsulated in polydimethylsiloxane (PDMS) : a numerical modelling

To mitigate climate change attributed to the electricity generation, there have been tremendous efforts in replacing fossil fuels with renewable energies in the electricity sector. For this purpose, wearable thermoelectric generators (WTEGs) are the most promising direct and green power generation technique for portable electronics. In spite of extensive research, there is a trade-off relationship between the flexibility of WTEGs and their power output. Thus, this research aims to improve the performance of a flexible WTEG through differing thermal conditions around the hot and cold junctions. Accordingly, the PDMS substrate of a flexible WTEG is segmented into two layers, whereas each layer is individually filled with different fillers. Accordingly, three different patterns are proposed for the segmentation. Then, using COMSOL Multiphysics software, the output voltage and power of the specified patterns are analyzed and compared with those of an original flexible WTEG. Results concluded that releasing the thermoelectric legs from PDMS coating can remarkably improve the output voltage as well as the power generation. In addition, with regard to the segmentation pattern, adding fillers to the PDMS layers has a twofold effect on the voltage and power generation. Precisely, the thickness of each segment should be taken into consideration for selecting an appropriate filler. This work paves the way for enhancing the performance of flexible WTEGs, which ultimately leads to low carbon and energy-efficient electricity generation

Optimum design of reinforced concrete retaining walls with the flower pollination algorithm

The flower pollination algorithm (FPA) is anefficient metaheuristicoptimizationalgorithm mimickingthe pollinationprocessof flowering species. In this study, FPA is applied, for first time, to the optimum design of reinforced concrete (RC) cantilever retaining walls. It is foundthat FPA offers important savings with respect to conventional design approachesand that it outperformsgenetic algorithm (GA)andthe particle swarm optimization (PSO) algorithm in this designproblem.Furthermore, parameter tuning reveals that the best FPA performance is achieved for switch probability values ranging between 0.4 and 0.7, a population size of 20 individualsand aLévy flightstep sizescale factor of 0.5. Finally, parametric optimum designs show that theoptimumcost of RC retaining walls increases rapidly with the wallheight and smoothly with the magnitude of surcharge loadin

Spatial layout planning in sub-surface rail station design for effective fire evacuation

The London Underground network is a crucial part of the transportation system in one of only four ‘Alpha’ world cities. The other three – Paris, New York and Tokyo – also have such sub-surface railway transport systems that may benefit from this shape grammar station design process in a future research proposal. In London’s case, the passenger flow rates are the underlining factor in sizing infrastructure where passengers have access – it is therefore this criterion that provides the basis for the shape grammar formulation for the largest, oldest and one of the most complex underground systems in the world. The research aims to improve passenger fire evacuation times, with due cognisance of the growth of numbers using the system, and its present susceptibility to terrorist attacks taken into account. The proposed shape grammar approach will provide for generation of spatial layouts, based upon visual rules of shape recognition, replacement / union, their connectivity and spatial relationships. The paper concentrates on definition and implementation of novel shape grammar design rules that incorporate station planning design knowledge, and in particular also discusses designers’ fire risk assessment approach and related knowledge that is also needed to produce credible station design solutions. Development, to date, of the proposed artificially intelligent CAD environment is also described along with parallel theoretical research. The proposed CAD interface provides familiarity to the designer and avoids incompatibility issues regarding drawing exchange format between various software systems. The shape grammar layouts produced will be tested in SIMULEX, a commercially available evacuation package, and be compared against ‘traditionally’ designed layouts to demonstrate improvements of preliminary ‘reference’ designs, which follow the standard London Underground design process as a later stage of this research