Variations In Channels Research Articles

Plastic Events of the Vestibular Nucleus: the Initiation of Central Vestibular Compensation.

Vestibular compensation is a physiological response of the vestibular organs within the inner ear. This adaptation manifests during consistent exposure to acceleration or deceleration, with the vestibular organs incrementally adjusting to such changes. The molecular underpinnings of vestibular compensation remain to be fully elucidated, yet emerging studies implicate associations with neuroplasticity and signal transduction pathways. Throughout the compensation process, the vestibular sensory neurons maintain signal transmission to the central equilibrium system, facilitating adaptability through alterations in synaptic transmission and neuronal excitability. Notable molecular candidates implicated in this process include variations in ion channels and neurotransmitter profiles, as well as neuronal and synaptic plasticity, metabolic processes, and electrophysiological modifications. This study consolidates the current understanding of the molecular events in vestibular compensation, augments the existing research landscape, and evaluates contemporary therapeutic strategies. Furthermore, this review posits potential avenues for future research that could enhance our comprehension of vestibular compensation mechanisms.

Diagenesis Variation in Different Distributary Channels of Shallow Water Lacustrine Delta Deposits and Implication for High-Quality Reservoir Prediction: A Case Study in the Chang 8 Member in Caijiamiao Area, Sw Ordos Basin, China

Tight oil reservoirs are considered important exploration targets in lacustrine basins. High-quality reservoir prediction is difficult as the reservoirs have complex distributions of depositional facies and diagenesis processes. Previous research has found that the diagenesis process of tight oil sandstones varies greatly in different depositional facies. However, diagenesis variation in different depositional facies is still poorly studied, especially in distributary channels of shallow water delta deposits in lacustrine basins. Based on the description of core samples, the observation of rock slices, the interpretation of well logging data, and the analysis of porosity and permeability data, the differences in the lithofacies types, diagenesis processes, and pore structures of different distributary channels have been clarified. Ultimately, a model of diagenesis and reservoir heterogeneity distribution in the shallow-water delta of Chang 8 Member of the Yanchang Formation in the Caijiamiao area of the Ordos Basin has been established. This research indicates that the main distributary channels in the study area are dominated by massive bedding sandstone lithofacies, while the secondary distributary channels are primarily characterized by cross-bedding sandstone lithofacies. There are significant differences in the compaction, dissolution, and cementation of authigenic chlorite and carbonate among different parts of the distributary channels. Plastic mineral components, such as clay and mica, are abundant in sheet sands, and are more influenced by mechanical and chemical compaction. Influenced by the infiltration of meteoric water and hydrocarbon generation, dissolution pores are relatively well-developed in the underwater distributary channel reservoirs. A large amount of carbonate cementation, such as calcite and siderite, is found within the sandstone at the interface between sand and mud. The occurrence of authigenic chlorite exhibits a clear sedimentary microfacies zonation, but there is little difference in the kaolinite and siliceous cementation among different microfacies reservoirs. Finally, a model of diagenetic differences and reservoir quality distribution within dense sand bodies has been established. This model suggests that high-quality reservoirs are primarily developed in the middle of distributary channels, providing a theoretical basis for the further fine exploration and development of oil and gas in the study area.

Instability of discount-rate and cash-flow channels of stock returns: a nonparametric approach

ABSTRACT According to the log-linear return approximation, the ability of a predictor to predict future stock returns may arise from its ability to predict either the cash flows or the discount rates, or both. This paper introduces a novel nonparametric approach to investigating the time variability in the predictability channels of the equity premium within a present-value framework. Using the existing return predictors, including the measures of economic uncertainty and sentiment, we document strong time variation in both discount-rate and cash-flow channels. In comparison, the predictability of the equity premium through the cash-flow channel is more pronounced than through the discount-rate channel.

The Variation in Boulder Bars Triggered by the 2018 Sedongpu Natural Dam Failure in the Yarlung Tsangpo River

Natural dams are formed most often in narrow, steep valleys in high mountains. The outburst floods triggered by natural dam failures result in the topography and landforms successively being altered. Boulder bars are common natural structures that are selected here to quantitatively evaluate the impact of outburst floods on the topographical and landform variations in downstream channels. In this study, we selected the Sedongpu natural dam on the Yarlung Tsangpo River formed as a result of a landslide in 2018 as an example, and studied the geomorphological changes in a river reach located 173 km downstream of the Sedongpu natural dam. The sizes and shapes of the boulder bars in this area were statistically analyzed. The results show that there are three shape types of boulder bars in this area, i.e., sickle, bamboo leaf and oval. Furthermore, it found that the relationship between the lengths and widths of boulder bars is similar before and after outburst floods, as is the relationship between perimeters and lengths of boulder bars, which means these relationships are not affected by outburst floods. And the perimeters of boulder bars are almost twice their lengths. In addition, the relationship between the areas and lengths of boulder bars follows a power function. The most important finding is that the riverine morphological features conserved self-similarity due the influence of the outburst flood erosion triggered by a natural dam failure. This finding adds to the previous observations since dam failures introduce sudden and dominating impacts on river systems.

Effect of high-intensity vibration parameter on droplet transport characteristics in gas channel of proton exchange membrane fuel cell

In aerospace applications, proton exchange membrane fuel cells are subject to high-intensity vibration. Vibration has a substantial effect on water transport in fuel cells. However, there is a lack of research on the effects of multi-directional and high-intensity vibration conditions on fuel cells. In this study, the droplet transport characteristics in the gas channel under high-intensity vibration conditions are investigated for the first time. Moreover, the effects of vibration direction and vibration frequency on the droplet dynamic transport process are specifically studied. The droplet transport state, drainage performance, and pressure drop variation in the gas channel under different vibration conditions are analyzed and interpreted. The results show that low-frequency vibration in the longitudinal direction is more conducive to the droplet discharge, and the pressure drop undergoes a periodic change corresponding to the vibration frequency. Vertical vibration promotes droplet detachment from the gas diffusion layer surface, which contributes to the reduction in water coverage ratio on its surface, despite an increase in the channel pressure drop. Under the influence of horizontal vibration, droplets are more susceptible to adsorption on the channel sidewalls and turn into a liquid film, which leads to a longer discharge time and a reduction in pressure drop.

Evaluate climate change and anthropogenic activities influencing geochemical variations in sediment between and within the avulsion period in the Lower Yellow River avulsion channels

The geochemical data from sediments in avulsion channels provide historical evidence of climate change and human-induced alterations in river basin environments. The present study focused on the particle size of sediments in cores and the level of geochemical variation in avulsion channels of the Lower Yellow River Delta (YRD), China. The sediment samples were collected in a depth range of 20–400 cm in avulsion channels. The collected samples were analyzed for sediment particle size and geochemical composition using standard methods. The results demonstrated rapid increases in agriculture practices, rainfall pattern changes, and terrestrial sediment runoff reduction in river basins after the 1960s. The reduced sediment loads in the Sanmenxia Reservoir significantly changed the sediment grain size and geochemical levels in the avulsion channel from August 1960.8 to January −1961.1. In particular, TC, TN, and C/N levels decreased with increasing sediment depth. The C/N values of <12 denoted completely reduced terrestrial sources of organic matter in the channel during the August 1960–January 1961 period compared to the July 1953–August 1960 period. The two-way ANOVA p-values were (p <0.016-p<0.001) strong between the avulsion periods but had no significant variation within the avulsion periods. We emphasize that this study provides a close interplay of different historical periods of geochemical variation in avulsion channel sediments in the alluvial fan YRD, and we argue that the evolution of the middle upstream river basin was subjective by climate change and human developmental actions, which impacted the YRD. In particular, reservoir-interrupted water flow and sediment reduction impacts associated with geochemical fluctuations are documented in the YRD.

Enhancing energy efficiency and heat transfer performance of engine oil flow through hybrid nanoparticles in convergent/divergent channel

Engine oil (EO) is employed as a lubricant in various machinery engines. Efficient heat transfers are a fundamental requirement for all processes. To improve heat transfer rates and reduce the energy loss caused by high temperatures, this study focuses on incorporating Iron Oxide (Fe3O4) and Cupper Oxide (CuO) into the engine oil as suspended particles. However, the focus of this research paper is to analyze entropy generation in a convergent/divergent channel that contains a hybrid nanofluid. Mathematical modeling is utilized to present the continuity, momentum, and energy equations. Using the resemblance transformation variables, the governing dimensional partial differential equations (PDEs) are transformed into a system of non-dimensional ordinary differential equations (ODEs), which are then resolved in ascending order through the BVP4c scheme. The graphical results illustrate the effects of various parameters on fluid velocity, temperature, entropy generation, and Bejan number. The study explores changes in velocity profiles under different Hartmann numbers, revealing opposing variations in divergent and convergent channels. Velocity profiles exhibit similar patterns when varying the porosity parameter. In the convergent passage, a higher porosity parameter results in a higher temperature field. Entropy rises against Eckert and Hartmann numbers in both Convergent and Divergent cases. These insights aid in designing and optimizing machinery engines.

A biophysically comprehensive model of urothelial afferent neurons: implications for sensory signalling in urinary bladder.

The urothelium is the innermost layer of the bladder wall; it plays a pivotal role in bladder sensory transduction by responding to chemical and mechanical stimuli. The urothelium also acts as a physical barrier between urine and the outer layers of the bladder wall. There is intricate sensory communication between the layers of the bladder wall and the neurons that supply the bladder, which eventually translates into the regulation of mechanical activity. In response to natural stimuli, urothelial cells release substances such as ATP, nitric oxide (NO), substance P, acetylcholine (ACh), and adenosine. These act on adjacent urothelial cells, myofibroblasts, and urothelial afferent neurons (UAN), controlling the contractile activity of the bladder. There is rising evidence on the importance of urothelial sensory signalling, yet a comprehensive understanding of the functioning of the urothelium-afferent neurons and the factors that govern it remains elusive to date. Until now, the biophysical studies done on UAN have been unable to provide adequate information on the ion channel composition of the neuron, which is paramount to understanding the electrical functioning of the UAN and, by extension, afferent signalling. To this end, we have attempted to model UAN to decipher the ionic mechanisms underlying the excitability of the UAN. In contrast to previous models, our model was built and validated using morphological and biophysical properties consistent with experimental findings for the UAN. The model included all the channels thus far known to be expressed in UAN, including; voltage-gated sodium and potassium channels, N, L, T, P/Q, R-type calcium channels, large-conductance calcium-dependent potassium (BK) channels, small conductance calcium-dependent (SK) channels, Hyperpolarisation activated cation (HCN) channels, transient receptor potential melastatin (TRPM8), transient receptor potential vanilloid (TRPV1) channel, calcium-activated chloride(CaCC) channels, and internal calcium dynamics. Our UAN model a) was constrained as far as possible by experimental data from the literature for the channels and the spiking activity, b) was validated by reproducing the experimental responses to current-clamp and voltage-clamp protocols c) was used as a base for modelling the non-urothelial afferent neurons (NUAN). Using our models, we also gained insights into the variations in ion channels between UAN and NUAN neurons.

Natural variation in CYCLIC NUCLEOTIDE-GATED ION CHANNEL 4 reveals a novel role of calcium signaling in vegetative phase change in Arabidopsis.

The timing of vegetative phase change (VPC) in plants is regulated by a temporal decline in the expression of miR156. Both exogenous cues and endogenous factors, such as temperature, light, sugar, nutrients, and epigenetic regulators, have been shown to affect VPC by altering miR156 expression. However, the genetic basis of natural variation in VPC remains largely unexplored. Here, we conducted a genome-wide association study on the variation of the timing of VPC in Arabidopsis. We identified CYCLIC NUCLEOTIDE-GATED ION CHANNEL 4 (CNGC4) as a significant locus associated with the diversity of VPC. Mutations in CNGC4 delayed VPC, accompanied by an increased expression level of miR156 and a corresponding decrease in SQUAMOSA PROMOTER BINDING-LIKE (SPL) gene expression. Furthermore, mutations in CNGC2 and CATION EXCHANGER 1/3 (CAX1/3) also led to a delay in VPC. Polymorphisms in the CNGC4 promoter contribute to the natural variation in CNGC4 expression and the diversity of VPC. Specifically, the early CNGC4 variant promotes VPC and enhances plant adaptation to local environments. In summary, our findings offer genetic insights into the natural variation in VPC in Arabidopsis, and reveal a previously unidentified role of calcium signaling in the regulation of VPC.

The variation in basal channels and basal melt rates of Pine Island Ice Shelf

The variation in basal channels and basal melt rates of Pine Island Ice Shelf

A highly sensitive diaphragm pressure sensor based on fiber Bragg grating with multiprobe configuration

The demand for accurate low-pressure sensing has become indispensable across diverse industries and research domains, where meticulous pressure monitoring holds paramount significance. This research work presents the development of a multiprobe extrinsically sensitive low pressure fiber Bragg grating (FBG) sensor. Three distinct diaphragm-based FBG sensing probes, equipped with silicone diaphragms of 0.5 mm, 1 mm, and 2 mm thickness, are developed within a unified assembly. This design offers the flexibility to select a probe based on the pressure magnitude and desired sensitivity and resolution. The displacement of diaphragm centers within the probes, caused by pressure variations in gas pipe channels, is actuated through an FBG-cantilever system. The sensor exhibits a dynamic range spanning 0 to 10 psi, featuring a peak sensitivity of 1.635 nm/psi. With a negligible hysteresis of 0.2 % observed in a complete operational cycle, the sensor demonstrates consistent stability across various constant pressure conditions, characterized by an average transient of <1 %. Furthermore, cyclic testing reveals an average deviation of 1.58 % in sensor response. This innovative sensor offers promising avenues for industrial applications and research and development endeavors that necessitate precise and reliable pressure measurements in the low pressure domains.

Entropy generation rate analysis of turbocharger radial flow compressor in range from surge to choke

This study compares the local losses of a radial compressor in the range from surge to choke considering shock phenomena, boundary layer separation, and mixing mechanisms. For this purpose, formulation of the local entropy generation rate (EGR) is added to the computational fluid dynamics (CFD) solver, which models the turbulent flow field of the compressor through the RANS approach. For validation, the numerical pressure rise curve of the compressor is compared with the experimental data. The results indicate that at the design point, the impeller, diffuser, and the volute account for approximately 50.8%, 30.0%, and 12.3% of the EGR, respectively, with approximately 5% in the impeller backspace, 1% in the diffuser cavity, and less than 0.5% in the inlet duct. Approaching the surge condition, local losses due to mixing and shock waves decline while boundary layer losses increase. Based on comprehensive analysis of the leading-edge boundary layer, the largest dead-air zone is found at the design point, resulting in a lower diffusion entrance loss and a higher mixing loss. Furthermore, the EGR variation in the diffuser channel is investigated by shedding light on mixing dynamics and classification of the channel flow regime into three different zones based on mixing ratio (MR). The outcomes show that the flow regime tends to mix more quickly at a higher MR, resulting in a slight decrease in EGR, which benefits compressor performance. We demonstrate that the mixing rate of flow regimes decreases in both the leading-edge boundary layer and the radial diffuser approaching the surge margin.

Theoretical analysis and numerical simulation study on the structural optimization of conical channels in the center tube of a centrifugal radial bed

To improve the uniformities of the flow distributions in radial beds, different design methods for conical channels were developed, that is, proportional method, traditional linear method for minimizing the pressure difference between two ends of the channel, newly proposed improved linear method for minimizing the pressure axial variation in the whole channel, and improved multi-segment linear method that divide the channel into multi-segments with different inclination angles. The flow fields under different design methods and gas flow rates are then investigated by numerical simulation. The designation of the angle of the conical channel is particularly significant. Compared to the original structure, the proportional method has difficulty obtaining a proper inclination angle, whose inhomogeneity indices of the distributions of pressure drop η p and gas velocity η v may increase or decrease. The traditional linear method has lower inhomogeneity indices, for example, η v will decrease by ≥7.02%, which denotes more uniform flow distributions, while the improved linear and multi-stage linear methods have the lowest inhomogeneity indices, for example, η v will decrease by ≥12.12 and 13.60%, respectively. Besides, the latter two methods have good adaptability and robustness to fluctuations in the gas flow rate.

The Effect of Fox News on Health Behavior during COVID-19

AbstractIn the early weeks of the 2020 coronavirus (COVID-19) pandemic, the Fox News Channel advanced a skeptical narrative that downplayed the risks posed by the virus. We find that this narrative had significant consequences: in localities with higher Fox News viewership—exogenous due to random variation in channel positioning—people were less likely to adopt behaviors geared toward social distancing (e.g., staying at home) and consumed fewer goods in preparation (e.g., cleaning products, hand sanitizers, and masks). Using original survey data, we find that the effect of Fox News came not merely from its long-standing distrustful stance toward science, but also due to program-specific content that minimized the COVID-19 threat. Taken together, our results demonstrate the significant impact that misinformation in media coverage can exert on viewers’ beliefs and behavior, even in high-stakes situations.

Tuning the hydraulic resistance by swelling-induced buckling of membranes in high-aspect-ratio microfluidic devices.

Controlling fluid flow in microfluidic devices and adapting it to varying conditions by selectively regulating hydrodynamic properties is of critical importance, as the field of microfluidics faces increasingly complex challenges in its wide range of applications. One way to manipulate flows in microfluidic devices is to introduce elastic elements that can be actively or passively deformed. In this work, we developed a membrane-based microfluidic device that allows us to study the deformation of swollen thin membranes as a function of the volume fractions in binary mixtures - here isopropanol and water. Furthermore, the membrane deformation can be used to control pressure-driven flows within the device. The device consists of two microfluidic channels separated by a thin membrane that deforms by a buckling-based mechanism, when the isopropanol volume fraction of the solvent flowing through it exceeds a certain volume fraction. The buckling membrane causes a sinusoidal height variation in both adjacent channels, resulting in a large increase in hydraulic resistance. We show that buckling-based deflections of elastic membranes can be used to amplify small changes in the degree of swelling to produce large changes in the microchannel geometry of the device, sufficient to manipulate the flow rate of pressure-driven flows in the microdevice.

Clinical relevance of potential self-medication drug interactions in antineoplastic and immune-modulating therapy among online pharmacy customers.

Modern oral antineoplastic and immune-modulating drugs offer an array of therapeutic advantages, and yet pose challenges in daily use for patients, physicians and pharmacists. In contrast to intravenous administration, these drugs are not subject to direct medical control. Recently, we have seen a huge rise in sales of non-prescription over-the-counter (OTC) medicines via the internet without any advice from a healthcare professional. The aim of this study was to investigate whether the risk of known potential drug-drug interactions between modern oral antineoplastic and immune-modulating drugs and OTC drugs differs between sales in traditional community pharmacies versus online pharmacies. Real-life sales data from community and online pharmacies were used as basis for the analysis. We determined the most frequently purchased antineoplastic and immune-modulating drug-substances in 14 local community pharmacies within the Munich area, Germany and identified the OTC substance groups that could potentially cause interactions with oncological therapies. Using sales data from 11 local community pharmacies and three online pharmacies, we investigated whether OTC purchases differed between the two sales channels. We identified 10 relevant OTC substance classes and detected significant variations in patients' preferred sales channels between the drug classes. Certain OTC drugs, which seem to be bought more often over the internet, pose risks during antineoplastic and immune-modulating therapy. Patients should therefore be proactively made aware of the corresponding risks in order not to jeopardize the activity of the antineoplastic and immune-modulating drugs and thus the success of their therapy.

Modeling and measurement of human body blockage loss at 28 GHz

ABSTRACT Millimeter-wave (mm-Wave) spectrum is an essential enabler to the fifth generation (5G) wireless technology. Humans are one of the most noticeable blockers that cause temporal variation in indoor radio channels. This paper presents human blockage measurements at 28 GHz, with several humans of different sizes. The effect of the crossing orientations of the human bodies is investigated for three different transmitter heights. A human blockage model based on the Fresnel diffraction scheme is shown to be applicable in estimating the human blockage loss in indoor radio links considering various body sizes, different crossing orientations, and different transmitter heights. The findings reported in this paper could help improve indoor radio channel models at 28 GHz bands for 5G technologies considering the presence of human body blockages.

The Analytical Solution of an Unsteady State Heat Transfer Model for the Confined Aquifer under the Influence of Water Temperature Variation in the River Channel

The effect of water temperature variation in a river channel on groundwater temperature in the confined aquifer it cuts can be generalized to a one-dimensional thermal convection-conduction problem in which the boundary water temperature rises instantaneously and then remains constant. The basic equation of thermal transport for such a problem is the viscous Burgers equation, which is difficult to solve analytically. To solve this problem, the Cole–Hopf transform was used to convert the second-order nonlinear thermal convection-conduction equation into a heat conduction equation with exponential function-type boundary conditions. Considering the difficulty of calculating the inverse of the image function of the boundary function, the characteristics and properties of the Laplace transform were used to derive the theoretical solution of the model without relying on the transformation of the boundary function, and the analytical solution was obtained by substituting the boundary condition into the theoretical solution. The analytical solution was used to analyze the temperature response laws of aquifers to parameter variation. Subsequently, a 40-day numerical simulation was conducted to analyze the boundary influence range and the results from the analytical method were compared to those from the numerical method. The study shows that: (1) the greater the distance from the river canal and the lower the aquifer flow velocity, the slower the aquifer temperature changes; (2) the influence range of the river canal boundary increases from 18.19 m to 23.19 m at the end of simulation period as the groundwater seepage velocity v increases from 0.08 m/d to 0.12 m/d; (3) the relative errors of the analytical and numerical methods are mostly less than 5%, confirming the rationality of the analytical solution.

A general pattern of non-spiking neuron dynamics under the effect of potassium and calcium channel modifications.

Electrical activity of excitable cells results from ion exchanges through cell membranes, so that genetic or epigenetic changes in genes encoding ion channels are likely to affect neuronal electrical signaling throughout the brain. There is a large literature on the effect of variations in ion channels on the dynamics of spiking neurons that represent the main type of neurons found in the vertebrate nervous systems. Nevertheless, non-spiking neurons are also ubiquitous in many nervous tissues and play a critical role in the processing of some sensory systems. To our knowledge, however, how conductance variations affect the dynamics of non-spiking neurons has never been assessed. Based on experimental observations reported in the biological literature and on mathematical considerations, we first propose a phenotypic classification of non-spiking neurons. Then, we determine a general pattern of the phenotypic evolution of non-spiking neurons as a function of changes in calcium and potassium conductances. Furthermore, we study the homeostatic compensatory mechanisms of ion channels in a well-posed non-spiking retinal cone model. We show that there is a restricted range of ion conductance values for which the behavior and phenotype of the neuron are maintained. Finally, we discuss the implications of the phenotypic changes of individual cells at the level of neuronal network functioning of the C. elegans worm and the retina, which are two non-spiking nervous tissues composed of neurons with various phenotypes.

Relationship marketing variation in multidyadic industrial channels with component supplier specification

Building strong relationships is central to the development and maintenance of effective industrial channels. However, while the relationship marketing literature is vast, our understanding of how multidyadic industrial channels impact relationship marketing models is limited. As many OEM supplier relationships are formed via component supplier specification by its industrial buyer, where freedom to enter and exit a relationship is externally restricted, the current relationship marketing literature is somewhat limited in explaining these relationships. This study examines the underlying differences in relationship marketing across the cases of component supplier specification and non-component supplier specification. We discuss key relationship variable differences across cases within the phases of relationship development, and the extant relationship marketing literature. We then present a research agenda for advancing our understanding of multidyadic industrial channels.