Experimental evaluation on noise reduction performance of a motorcycle helmet

Motorcycle helmets are generally thought to be only protection of motorcycle drivers against head injuries as well as loud noise in traffic. While there have been several papers on noise elimination capabilities of motorcycle helmets, no controlled study has been reported to compare different types of test conditions in literature. The purpose of this study is to assess noise reduction capacities of a motorcycle helmet under different types of acoustical loadings as well as environments and to identify better test condition. Firstly, a Head & Torso simulator with and without the motorcycle helmet in a built acoustical cabinet was exposed to digitally generated sound to investigate insertion loss values. Besides, the Head & Torso simulator was fixed onto a motorcycle to simulate actual driving conditions. Sound pressure levels were captured at the ear level to obtain insertion loss values in case of motorcycle noise for different engine speeds. By comparing calculated insertion losses, it was revealed that considerable differences existed between tests for different conditions. Beneficial interpretations were deduced and thus, a practical solution was presented for accurate measurements acoustic performance of the motorcycle helmets in laboratory conditions

A study of noise source localization in motorcycles

In civilized and developing countries, the number of the motorcycles in transportation systems is increasing day by day. With the growing demand of the motorcycles, the noise caused by these vehicles has constituted an important role in the noise pollution. On the other hand, the drivers are suffering from the permanent damages that are generated by the motorcycle noise. For overcoming these drawbacks, the first necessary is to determine the noise sources in motorcycles. The purposes of this study are the determination of the noise sources in motorcycles by sound intensity method and investigation of the effects of the motorcycle noises on the drivers. Firstly, sound levels were measured at idle mode and at three different engine speeds for investigated motorcycle by using the sound intensity probe. Besides these measurements, the sound levels were also captured at the ear level with and without a helmet. Then the results were analyzed by taking into the consideration of the helmet usage and the driving speed

Motional phase maps for estimating the effectiveness of granular dampers

This paper evaluates simple but general links between the operating dynamic motional phases and the non-linear energy dissipation characteristics of granular dampers. The Discrete Element Method is used to simulate a typical granular medium consisting of spherical particles in a cylindrical enclosure subjected to harmonic vibrations aligned both parallel and perpendicular with gravity. A set of equivalent experiments is conducted to verify the numerical model. A wide range of excitation frequency and amplitude are considered, to obtain many different motional phases, along with particle size and volume fill ratio. Granular motional phase maps are produced over amplitude-frequency plane that defines where the various motion phases are present providing rich information for the effectiveness of granular dampers. Findings show that high granular damping effectiveness is found in two distinct zones: where collective collisions with the enclosure are optimised and where fluidisation without convection is maximised. The most significant factors affecting these high effectiveness zones are identified and can be used to provide guidance for those seeking to design granular dampers to reduce vibrations in structures

On noise reduction of motorcycle helmets

Motorcycle helmets are mandatory on the safe driving, in spite of that the helmet usage rate decreases by the reason of discomfort. One of the most common complaints of the drivers is noise in the helmet. The noise may be structural bourne or air bourne. In this paper, measurements were performed to determine the external noise reduction of the motorcycle helmets, which is a preliminary study to improve the sound quality. The measurements were carried out on a specially designed field to provide a controlled acoustic environment. A Head & Torso simulator was used to measure noise in the built cabinet that produced by an omnidirectional sound source. The in-cab calibration was provided by in-house microphones. The excitation sounds were generated by using special software on the computer and the output was transmitted to the speaker cabinet via a sound card connected to an amplifier. Two types of motorcycle helmets were tested and the sound reduction results were compared

The dissipative characteristics of oblate particles in granular dampers

In numerical models for granular dampers, particles are generally considered to be perfect spheres. However, in practical engineering applications these particles can slightly deviate from being true spheres. It has been observed experimentally that sphericity, which defines the proximity degree of a shape to a sphere, plays an important role in the amplitude dependent behaviour of granular dampers. This paper mainly examines the significance of the sphericity level for slightly oblate particles in a granular damper that are subjected to sinusoidal vibrations in the same direction as standard gravity. This investigation is carried out by evaluating the dissipated power from the granular medium by utilizing three-dimensional discrete element method simulations. Apart from the effect of amplitude of vibrations in the dissipated power, the relative contributions of frictional and inelastic collisional damping mechanisms in the overall power dissipation, are also investigated for varying sphericity levels of the oblate particles

Defining alternative recovery strategies for reuse: An analysis of multiple case studies under the reuse umbrella

This study focuses on the role of the reuse recovery approach and its strategies in the circular economy through a product design lens. While the circular economy has been widely discussed, not all recovery strategies have been thoroughly investigated and understood alike. This research differentiates between reuse and other recovery strategies and defines three distinct opportunities under the ‘reuse umbrella’ – reuse, cascade and relink. For each opportunity, possible sub-opportunities are identified and elaborated. Through a multiple case study analysis, the sub-opportunities are elaborated with a "Design for X" approach into eight different strategies of reuse, including design for direct reuse, reconfiguration, material cascading, repurposing, component reuse, creative reuse, material reclamation and adaptive reuse. The research emphasises that the appropriateness of a reuse strategy depends on various aspects such as the context, users, industries, and material flows. Also, this study stresses the importance of reuse in promoting circular product development and consumption, providing valuable implications for businesses and designers.The research project received financial backing from the UKRI National Interdisciplinary Circular Economy Research programme (NICER

The Neurotoxicity of DOPAL: Behavioral and Stereological Evidence for Its Role in Parkinson Disease Pathogenesis

BACKGROUND: The etiology of Parkinson disease (PD) has yet to be fully elucidated. We examined the consequences of injections of 3,4-dihydroxyphenylacetaldehyde (DOPAL), a toxic metabolite of dopamine, into the substantia nigra of rats on motor behavior and neuronal survival. METHODS/PRINCIPAL FINDINGS: A total of 800 nl/rat of DOPAL (1 µg/200 nl) was injected stereotaxically into the substantia nigra over three sites while control animals received similar injections of phosphate buffered saline. Rotational behavior of these rats was analyzed, optical density of striatal tyrosine hydroxylase was calculated, and unbiased stereological counts of the substantia nigra were made. The rats showed significant rotational asymmetry ipsilateral to the lesion, supporting disruption of dopaminergic nigrostriatal projections. Such disruption was verified since the density of striatal tyrosine hydroxylase decreased significantly (p<0.001) on the side ipsilateral to the DOPAL injections when compared to the non-injected side. Stereological counts of neurons stained for Nissl in pars compacta of the substantia nigra significantly decreased (p<0.001) from control values, while counts of those in pars reticulata were unchanged after DOPAL injections. Counts of neurons immunostained for tyrosine hydroxylase also showed a significant (p=0.032) loss of dopaminergic neurons. In spite of significant loss of dopaminergic neurons, DOPAL injections did not induce significant glial reaction in the substantia nigra. CONCLUSIONS: The present study provides the first in vivo quantification of substantia nigra pars compacta neuronal loss after injection of the endogenous toxin DOPAL. The results demonstrate that injections of DOPAL selectively kills SN DA neurons, suggests loss of striatal DA terminals, spares non-dopaminergic neurons of the pars reticulata, and triggers a behavioral phenotype (rotational asymmetry) consistent with other PD animal models. This study supports the "catecholaldehyde hypothesis" as an important link for the etiology of sporadic PD

NRF2 Activation Restores Disease Related Metabolic Deficiencies in Olfactory Neurosphere-Derived Cells from Patients with Sporadic Parkinson's Disease

Extent: 14p.Background: Without appropriate cellular models the etiology of idiopathic Parkinson’s disease remains unknown. We recently reported a novel patient-derived cellular model generated from biopsies of the olfactory mucosa (termed olfactory neurosphere-derived (hONS) cells) which express functional and genetic differences in a disease-specific manner. Transcriptomic analysis of Patient and Control hONS cells identified the NRF2 transcription factor signalling pathway as the most differentially expressed in Parkinson’s disease. Results: We tested the robustness of our initial findings by including additional cell lines and confirmed that hONS cells from Patients had 20% reductions in reduced glutathione levels and MTS [3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)- 2-(4-sulfophenyl)-2H-tetrazolium, inner salt] metabolism compared to cultures from healthy Control donors. We also confirmed that Patient hONS cells are in a state of oxidative stress due to higher production of H2O2 than Control cultures. siRNA-mediated ablation of NRF2 in Control donor cells decreased both total glutathione content and MTS metabolism to levels detected in cells from Parkinson’s Disease patients. Conversely, and more importantly, we showed that activation of the NRF2 pathway in Parkinson’s disease hONS cultures restored glutathione levels and MTS metabolism to Control levels. Paradoxically, transcriptomic analysis after NRF2 pathway activation revealed an increased number of differentially expressed mRNAs within the NRF2 pathway in L-SUL treated Patient-derived hONS cells compared to L-SUL treated Controls, even though their metabolism was restored to normal. We also identified differential expression of the PI3K/AKT signalling pathway, but only post-treatment. Conclusions: Our results confirmed NRF2 as a potential therapeutic target for Parkinson’s disease and provided the first demonstration that NRF2 function was inducible in Patient-derived cells from donors with uniquely varied genetic backgrounds. However, our results also demonstrated that the response of PD patient-derived cells was not co-ordinated in the same way as in Control cells. This may be an important factor when developing new therapeutics.Anthony L. Cook, Alejandra M. Vitale, Sugandha Ravishankar, Nicholas Matigian, Greg T. Sutherland, Jiangou Shan, Ratneswary Sutharsan, Chris Perry, Peter A. Silburn, George D. Mellick, Murray L. Whitelaw, Christine A. Wells, Alan Mackay-Sim and Stephen A. Woo

Mouse models of neurodegenerative disease: preclinical imaging and neurovascular component.

Neurodegenerative diseases represent great challenges for basic science and clinical medicine because of their prevalence, pathologies, lack of mechanism-based treatments, and impacts on individuals. Translational research might contribute to the study of neurodegenerative diseases. The mouse has become a key model for studying disease mechanisms that might recapitulate in part some aspects of the corresponding human diseases. Neurode- generative disorders are very complicated and multifacto- rial. This has to be taken in account when testing drugs. Most of the drugs screening in mice are very di cult to be interpretated and often useless. Mouse models could be condiderated a ‘pathway models’, rather than as models for the whole complicated construct that makes a human disease. Non-invasive in vivo imaging in mice has gained increasing interest in preclinical research in the last years thanks to the availability of high-resolution single-photon emission computed tomography (SPECT), positron emission tomography (PET), high eld Magnetic resonance, Optical Imaging scanners and of highly speci c contrast agents. Behavioral test are useful tool to characterize di erent ani- mal models of neurodegenerative pathology. Furthermore, many authors have observed vascular pathological features associated to the di erent neurodegenerative disorders. Aim of this review is to focus on the di erent existing animal models of neurodegenerative disorders, describe behavioral tests and preclinical imaging techniques used for diagnose and describe the vascular pathological features associated to these diseases