Generalized Analysis of Elastic Wave Dispersion Asymmetries in Moving Periodic Media

This work presents a generalized physical interpretation of unconventional dispersion asymmetries associated moving elastic solids. By shifting the notion from systems with time-variant material fields to physically traveling materials, the newly adopted paradigm provides an eloquent take on the dispersion problem and, in the process, highlights discrepancies between both schemes. Equations governing the motion of an elastic rod with a prescribed moving velocity observed from a stationary reference frame are used to predict propagation patterns and asymmetries in wave velocities induced as a result of the induced linear momentum bias. Three distinct scenarios corresponding to a moving rod with a constant modulus, a spatially varying one, and one that varies in space and time are presented. These cases are utilized to extract and interpret correlations pertaining to directional velocities, dispersion patterns, as well as nature of band gaps between moving periodic media and their stationary counterparts with time-traveling material properties. A linear vertical shear transformation is derived and utilized to thoroughly neutralize the effect of the moving velocity on the resultant dispersion characteristics. Finally, dispersion contours associated with the transient response of a finite moving medium are used to validate the entirety of the presented framework

Proposing a new approach to applying pervasive computing in agriculture environments

The resource management in agriculture environments is very important. Using smart controls will be one of the most eminent ways of managing. These resources such as water and plant nutrition. In this paper researcher are going to present a special program in which provide necessary resources for growing plant by using data sensors based on environment conditions. Firstly, it is gained a few data from soil, climate and plant conditions by using sensors and made context by processing all the data. In next stage the presented approach will do its own calculations on the basis of conditions. It can be said that researchers are used fuzzy logic for calculations because of complex data. Then researchers by using actuators can make decision for environment. In this paper, because of injecting nutrition on the basis of its conditions in to soil and plant necessary, plants can frequently use suitable quanta of nutrition and 2026;, won2019;t be on stress danger

The role of BK potassium channels in analgesia produced by alpha-2 adrenergic receptors

BACKGROUND AND OBJECTIVE: Millions of people suffer from pain worldwide, and annually, great economic costs are imposed on societies for pain relief. Analgesics such as alpha-2 adrenergic receptor agonists, which have low risk of complications, can be effective in assuaging pain and reducing costs. According to former studies, potassium channels play an important role in the analgesic mechanism of these receptors. This study aimed to determine the role of BK potassium channels in analgesia induced by alpha-2 adrenergic receptors. METHODS: This study was performed on 56 male Wistar rats weighing 250-300 g that were divided into seven groups of eight rats. We administered 0. 7 mg/kg intraperitoneal (IP) injection of clonidine, 1 mg/kg IP injection of yohimbine, and 5 mg/kg intracerebroventricular (ICV) injection of yohimbine. Iberiotoxin at a dose of 100 nm was also injected ICV. Normal saline and DMSO were applied as solvents. Pain severity was evaluated using formalin test at a concentration of 2%. FINDINGS: The chronic pain induced by formalin injection was relieved by IP injection of 0. 7 mg/kg clonidine. Moreover, 5 μg/kg and 1 μg/kg ICV administration of yohimbine with mean chronic pain scores of 2. 29±0. 13 and 2. 09±0. 07, respectively, could significantly inhibit analgesic effect of clonidine with mean chronic pain score of 1. 55±0. 14 (p<0. 001). ICV injection of iberiotoxin with mean chronic pain score of 2. 33±0. 16 at a dose of 100 nm significantly diminished analgesic effects of clonidine. CONCLUSION: Alpha-2 adrenergic receptor agonists could induce analgesia in the animals, and the antagonist of this receptor inhibited the analgesic effect of agonists of these receptors. BK channel inhibition prevented analgesic effect of adrenergic receptor agonists, as well. © 2016, Babol University of Medical Sciences. All rights reserved

Molecular mechanism of glucocorticoid action

Adrenal corticosteroids are involved in multiple aspects of homeostatic control. The early delayed ( <2h) action of glucocorticoids is mediated by rapid induction of mRNA and protein synthesis. Within this time -frame, glucocorticoids potently modify the electrical excitability of target cells through regulation of ion channels. Increasing evidence suggests that in neurones and endocrine cells, large conductance calcium - and voltage- activated potassium channels (BK channels) are important targets for glucocorticoid action. The aim of this thesis project was to investigate the mechanisms by which glucocorticoid hormones regulate the activity of BK channels in human embryonic kidney 293 (HEK 293) cells as the model system for glucocorticoid- action. It was shown that glucocorticoids act via endogenously expressed type II receptors in a concentration- and time -dependent manner in these cells. Dexamethasone (100 nM) had no significant effect on Dexrasl mRNA but significantly increased serum- and glucocorticoid- induced protein kinase 1 (SGK-1) mRNA. Biochemical analysis showed that SGK-1 protein is increased by dexamethasone in a Triton X-100 insoluble fraction. Further work was directed toward analysing the possible association of SGK -1 and protein phosphatases with two BK channel cc-subunit variants: ZERO-BK and STREX-BK, the latter contains the 59 amino -acid splice insert encoded by the stress hormone induced exon (STREX). HEK 293 cells stably expressing the respective channel subunits were analysed. Immunoprecipitations with antisera directed against the BK channel cc-subunits showed that protein phosphatase 2A (PP2A) but not SGK-1 is constitutively associated with the STREX as well as the ZERO variant BK channel. Furthermore, the cytoplasmic C- terminal segment of the STREX-BK channel was necessary for cell -surface expression of the channel and the association of the channel with PP2A. Dexamethasone failed to change the apparent amount of immunoreactive PP2A co-immunoprecipitating with the channel. In conclusion: SGK-1 but not Dexrasl is a protein rapidly induced by dexamethasone in HEK293 cells. PP2A but not SGK -1 is in complex with both ZERO and STREX-BK channels, and dexamethasone does not alter this association. The cytoplasmic tail of the BK channels is essential for PP2A interaction

Marginalizing Risk

A major focus of finance is reducing risk on investments, a goal commonly achieved by dispersing the risk among numerous investors. Sometimes, however, risk dispersion can cause investors to underestimate and under-protect against risk. Risk can even be so widely dispersed that rational investors individually lack the incentive to monitor it. This Article examines the market failures resulting from risk dispersion and analyzes when government regulation may be necessary or appropriate to limit these market failures. The Article also examines how such regulation should be designed,including the extent to which it should limit risk dispersion in the first instance

Brown syndrome in one pair of dizygotic twins: a case report

This is an Open Access article distributed under the terms of the Creative Commons Attribution Licens

Numerical Study of Cloud-Sized Droplet Impact and Freezing on Superhydrophobic Surfaces

In-flight icing is a serious meteorological hazard caused by supercooled cloud particles (with an average size of 20–50 µm) that turn into ice as an immediate consequence of impact with an aircraft, and it poses a serious risk to the safety of the aircraft and its passengers. Anti-icing surface treatment is a potential solution to mitigate ice accretion and maintain optimal flying conditions. Superhydrophobic coatings inspired by nature (e.g., lotus leaf) have attracted much attention in recent years due to their excellent water repellent properties. These coatings have been extensively applied on various substrates for self-cleaning, anti-fogging, and anti-corrosive applications. The performance of these coatings depends on the chemical composition and their rough hierarchical surface morphology composed of micron and sub-micron-sized structures. Recently, there has been an increased interest to fabricate superhydrophobic coatings that can repel droplets of cloud-relevant sizes (20–50 µm) before they freeze to the surface in practical flight conditions (i.e., icephobic surfaces). The main goal of this work was to numerically model the hydrodynamic and thermal behaviour of cloud-sized droplets on superhydrophobic surfaces when interacting with micron-sized surface features. Consequently, by correlating the hydrophobicity and the icephobicity of the surface, we found viable solutions to counteract icing and to prevent ice accumulation on critical aerodynamic surfaces. For this purpose, we developed a computational model to analyze the hydrodynamics of the impact of the micro-droplet on a micro-structured superhydrophobic surface under room temperature and freezing (including rapid-cooling and supercooling) conditions. All coding and implementations were carried out in the OpenFOAM platform, which is a collection of open-source C++ libraries for computational continuum mechanics and CFD analysis. Superhydrophobic surfaces were directly modelled as a series of fine, micro-structured arrays with defined cross sections and patterns. Surface chemistry was included in the simulations using a dynamic contact angle model that describes well the hydrodynamics of a micro-droplet on rough surfaces. A multi-region transient solver for incompressible, laminar, multi-phase flow of non-isothermal, non-Newtonian fluids with conjugate heat transfer boundary conditions between solid and fluid regions was developed to simulate both the dynamics of the micro-droplet impact on the substrate and the associated heat transfer inside the droplet and the solid bulk simultaneously. In addition, a phase change (freezing) model was added to capture the onset of ice formation and freezing front of the liquid micro-droplet. The computational model was validated using experimental data reported in the literature. In addition, an analytical model was derived using the balance of energy before impact and at the maximum spreading stage, which we found to be in good agreement with the data obtained from simulations. Since aluminum (Al) is the base material used in aerospace industries, the thermo-physical properties of aluminum were extensively used in our simulations. Comparing laser-patterned aluminum substrates with a ceramic base composite material that has a low thermal diffusivity (such as titanium-dioxide), we showed that the onset of icing was significantly delayed on the ceramic-based substrate, as the droplet detached before freezing to the surface. Finally, a freezing model for the supercooled water droplet based on classical nucleation theory was developed. The model is an approximation for a supercooled droplet of the recalescence step, which was assumed to be initiated by heterogeneous nucleation from the substrate. This research extended our knowledge about the hydrodynamic and freezing mechanisms of a micro-droplet on superhydrophobic surfaces. The developed solvers can serve as a design tool to engineer the roughness and thermo-physical properties of superhydrophobic coatings to prevent the freezing of cloud-sized droplets in practical flight conditions