Magneto-hydrodynamics of couple stress lubricants in combined squeeze and shear in parallel annular disc viscous coupling systems

This article presents predictive analysis of load-carrying capacity, tractive efficiency and response time of parallel annular discs intervened with a film of lubricant under combined shear and squeeze film motions. This configuration represents operational characteristics of viscous coupling systems. In particular, the case of viscous dampers for tractive torque generation and distribution in all-wheel-drive off road vehicles is studied. Various forms of lubricant behaviour, from idealised Newtonian to that of non-Newtonian silicone-based fluids and incompressible isothermal electrically conducting couple stress fluids, subjected to a magneto-hydrodynamic field are studied. The solution for the magneto-hydrodynamics includes combined solution of modified Reynolds equation and Stoke's micro-continuum for couple stress fluids in squeeze and shear with rotational fluid inertia, an approach not hitherto reported in the literature. It is shown that in general magneto-hydrodynamic couple stress fluids enhance the load-carrying capacity of the contact and inhibit the incidence of thin films, which can result in direct contact of surfaces. Rotational inertia decreases the load-carrying capacity, although in general the magneto-hydrodynamic fluids show better load-carrying capacity and tractive efficiency than the other alternatives. However, they exhibit a lower response time under the assumed isothermal condition. Nevertheless, the magneto-hydrodynamic fluids are best suited to applications in viscous coupling systems because of their controllability

A study on torsional vibration attenuation in automotive drivetrains using absorbers with smooth and non-smooth nonlinearities

The automotive industry is predominantly driven by legislations on stringent emissions. This has led to the introduction of downsized engines, incorporating turbocharging to maintain output power. As downsized engines have higher combustion pressures, the resulting torsional oscillations (engine order vibrations) are of broadband nature with an increasing severity, which affect noise and vibration response of the drive train system. Palliative devices, such as clutch pre-dampers and dual mass flywheel have been used to mitigate the effect of transmitted engine torsional oscillations. Nevertheless, the effectiveness of these palliative measures is confined to a narrow band of response frequencies. The nonlinear targeted energy transfer is a promising approach to study vibration mitigation within a broader range of frequencies, using nonlinear vibration absorbers (or nonlinear energy sinks – NESs). These devices would either redistribute vibration energy within the modal space of the primary structure, thus dissipating the vibrational energy more efficiently through structural damping, or passively absorb and locally dissipate a part of this energy (in a nearly irreversible manner) from the primary structure. The absence of a linear resonance frequency of an NES, enables its broadband operation (in contrast to the narrowband operation of current linear tuned mass dampers). Parametric studies are reported to determine the effectiveness of various smooth or non-smooth nonlinear stiffness characteristics of such absorbers. A reduced drivetrain model, incorporating single and multiple absorber attachments is used and comparison of the predictions to numerical integrations proves its efficacy

Early phase of plasticity-related gene regulation and SRF dependent transcription in the hippocampus

Hippocampal organotypic cultures are a highly reliable in vitro model for studying neuroplasticity: in this paper, we analyze the early phase of the transcriptional response induced by a 20 \ub5M gabazine treatment (GabT), a GABA-Ar antagonist, by using Affymetrix oligonucleotide microarray, RT-PCR based time-course and chromatin-immuno-precipitation. The transcriptome profiling revealed that the pool of genes up-regulated by GabT, besides being strongly related to the regulation of growth and synaptic transmission, is also endowed with neuro-protective and pro-survival properties. By using RT-PCR, we quantified a time-course of the transient expression for 33 of the highest up-regulated genes, with an average sampling rate of 10 minutes and covering the time interval [10 3690] minutes. The cluster analysis of the time-course disclosed the existence of three different dynamical patterns, one of which proved, in a statistical analysis based on results from previous works, to be significantly related with SRF-dependent regulation (p-value<0.05). The chromatin immunoprecipitation (chip) assay confirmed the rich presence of working CArG boxes in the genes belonging to the latter dynamical pattern and therefore validated the statistical analysis. Furthermore, an in silico analysis of the promoters revealed the presence of additional conserved CArG boxes upstream of the genes Nr4a1 and Rgs2. The chip assay confirmed a significant SRF signal in the Nr4a1 CArG box but not in the Rgs2 CArG box

Suicide Death Rate after Disasters: A Meta-Analysis Study

Background Disasters have undesirable effects on health among individuals such as psychosocial disorders which may lead lead to suicide in some cases. Thus, the present study aimed to measure the rate of suicide death after disasters all over the world. Methods In the present meta-analysis study, all of the articles published in English until the end of 2019 were probed in electronic databases such as Web of Science, PubMed, Cochrane Library, Science Direct, PsycINFO, PsycARTICLES, and Google Scholar. Then, the data were imported to STATA ver.13 software and analyzed through fixed- and random-effects models, meta-regression, and Cochrane statistical tests. Results A total of 11 studies including a sample size of 65495867 were considered. Suicide death rates before and after the disasters were calculated as 13.61 (CI95: 11.59-15.77) vs. 16.68 (CI95: 14.5-19:0) among the whole population, 28.36 (CI 95:11.29-45.43) vs. 32.17 (CI95: 17.71-46.62) among men, and 12.71 (CI95: 5.98-19.44) vs 12.69 (CI95: 5.17-20.21) among women. The rate of suicide death significantly increased in the whole population and men, while no significant difference was reported among women. Conclusion Suicide death rate increases after disasters indicating the destructive impact of this phenomenon on peoples' health. Therefore, implementing supportive and interventional measures is highly suggested after disasters in order to prevent suicide death among the affected people