Gate Closes Research Articles

Gap Junction Channel Regulation: A Tale of Two Gates-Voltage Sensitivity of the Chemical Gate and Chemical Sensitivity of the Fast Voltage Gate.

Gap junction channels are regulated by gates sensitive to cytosolic acidification and trans-junctional voltage (Vj). We propose that the chemical gate is a calmodulin (CaM) lobe. The fast-Vj gate is made primarily by the connexin's NH2-terminus domain (NT). The chemical gate closes the channel slowly and completely, while the fast-Vj gate closes the channel rapidly but incompletely. The chemical gate closes with increased cytosolic calcium concentration [Ca2+]i and with Vj gradients at Vj's negative side. In contrast, the fast-Vj gate closes at the positive or negative side of Vj depending on the connexin (Cx) type. Cxs with positively charged NT close at Vj's negative side, while those with negatively charged NT close at Vj's positive side. Cytosolic acidification alters in opposite ways the sensitivity of the fast-Vj gate: it increases the Vj sensitivity of negative gaters and decreases that of positive gaters. While the fast-Vj gate closes and opens instantaneously, the chemical gate often shows fluctuations, likely to reflect the shifting of the gate (CaM's N-lobe) in and out of the channel's pore.

IoT based Smart Car Parking System using RFID in a Community

With the growth of technology in the current decade, we are confronting a parking challenge. Because large towns have a dense population, there are many vehicles on the road, which causes parking and traffic problems. The globe is confronted with a new challenge that is vehicle parking. It is estimated that one million automobiles use oil on a daily basis. This paper proposes an RFID based car parking system in a community. This system was created with the assistance of the internet of things (IOTs). IoT mainly involves the exchange of information or data between two physical devices. In the suggested system, an Arduino Uno microcontroller, ESP32, RFID sensors and IR sensors are used. The value of automation is growing every day. The primary function of Arduino in the proposed system is to serve as a platform for communicating digital devices and interactive objects capable of sensing and controlling physical components. The proposed system was built using an Arduino Uno board for vehicle parking and a ESP32 to connect the parking area to the web. In order to obtain information regarding the vacancy position of the parking slot, the suggested system included an infrared sensor in each slot. Therefore, to determine whether or not a person is in the database for the car parking system, RFID sensors are used. If the driver is listed in the database, the car will be allowed to enter the parking lot and the gate will open when the motors rotate in a clockwise direction. When the gate closes, the door will rotate in an anticlockwise direction and shows the user via led. From this proposed system, we get the information about the vacancy position of parking spot and notify the user through website. Keywords—IOT, RFID, IR Sensors, ESP32, Arduino

Update Scheduling for ADMM-Based Energy Sharing in Virtual Power Plants Considering Massive Prosumer Access

With the proliferation of distributed energy resources (DERs), electricity consumers in virtual power plants (VPPs) are transitioning into prosumers and are encouraged to share surplus energy with peers. Nevertheless, large-scale energy sharing among thousands of prosumers may encounter communication-related challenges. Communication network congestion may result in a significant increase in the negotiation waiting time to reach a sharing agreement, and potentially risks exceeding the deadline of negotiation before the market gate closes, rendering energy sharing ineffective. This paper proposes an online partial-update algorithm for the alternating direction method of multipliers (ADMM)-based energy sharing. By restricting the update connection between the VPP and the prosumers, the algorithm selects a subset of the prosumers participating in ADMM updates each round, hence eliminating the excessively long waiting time caused by communication congestion. Considering the delay induced by massive prosumer communication access requests, a method for determining the optimal number of prosumers participating in updates is provided. To fully utilize the limited update opportunities, a fair and efficient prosumer update scheduling policy is designed. The VPP schedules the participation of prosumers in updates such that the convergence-critical prosumers receive higher priority, yet every prosumer is granted sufficient update opportunities. Additionally, the extra computation and communication overheads brought by the prosumer scheduling are minimized, allowing the whole algorithm to be executed in real time. Numerical studies are conducted to validate the effectiveness of the algorithm and its performance in reducing the overall convergence time.

Smart Traffic Light Control System with Automatic Vehicle Speed Breaker

The aim of the project is to design a smart traffic light control system interfaced with a barrier gate and an LDR based traffic light control system. When the signal timing changes a delay is provided with the help of a microcontroller, pop up barrier before the zebra crossing will open or close to allow vehicles to pass. When the signal is red the interfaced barrier gate closes and a buzzer notifies the closing of gate, thereby blocking the traffic but when the signal is green the same barrier opens and allows a proper flow of vehicles to avoid traffic congestion. We provide a time delay for all signals to change and buzzer action by using ESP32 microcontroller. ESP32 microcontroller is used for signal timing change as well as street light control according to LDR. Smart Street light which operates with the help of sensors Microcontrollers are programmed in such a way to adjust their timing and phasing to meet changing traffic conditions. The circuit, besides being reliable and compact, is also cost effective. This project presents the way of conservation of energy by reducing electricity wastage as well as to reduce the man power. The project uses light emitting diodes (LED) that do not consume an enormous amount of electricity. LDR is used as a sensor for the functioning of street lights effectively.

Local accumulation time for diffusion in cells with gap junction coupling.

In this paper we analyze the relaxation to steady state of intracellular diffusion in a pair of cells with gap-junction coupling. Gap junctions are prevalent in most animal organs and tissues, providing a direct diffusion pathway for both electrical and chemical communication between cells. Most analytical models of gap junctions focus on the steady-state diffusive flux and the associated effective diffusivity. Here we investigate the relaxation to steady state in terms of the so-called local accumulation time. The latter is commonly used to estimate the time to form a protein concentration gradient during morphogenesis. The basic idea is to treat the fractional deviation from the steady-state concentration as a cumulative distribution for the local accumulation time. One of the useful features of the local accumulation time is that it takes into account the fact that different spatial regions can relax at different rates. We consider both static and dynamic gap junction models. The former treats the gap junction as a resistive channel with effective permeability μ, whereas the latter represents the gap junction as a stochastic gate that randomly switches between an open and closed state. The local accumulation time is calculated by solving the diffusion equationin Laplace space and then taking the small-s limit. We show that the accumulation time is a monotonically increasing function of spatial position, with a jump discontinuity at the gap junction. This discontinuity vanishes in the limit μ→∞ for a static junction and β→0 for a stochastically gated junction, where β is the rate at which the gate closes. Finally, our results are generalized to the case of a linear array of cells with nearest-neighbor gap junction coupling.

Calmodulin-Connexin Partnership in Gap Junction Channel Regulation-Calmodulin-Cork Gating Model.

In the past four decades numerous findings have indicated that gap junction channel gating is mediated by intracellular calcium concentrations ([Ca2+i]) in the high nanomolar range via calmodulin (CaM). We have proposed a CaM-based gating model based on evidence for a direct CaM role in gating. This model is based on the following: CaM inhibitors and the inhibition of CaM expression to prevent chemical gating. A CaM mutant with higher Ca2+ sensitivity greatly increases gating sensitivity. CaM co-localizes with connexins. Connexins have high-affinity CaM-binding sites. Connexin mutants paired to wild type connexins have a higher gating sensitivity, which is eliminated by the inhibition of CaM expression. Repeated trans-junctional voltage (Vj) pulses progressively close channels by the chemical/slow gate (CaM’s N-lobe). At the single channel level, the gate closes and opens slowly with on-off fluctuations. Internally perfused crayfish axons lose gating competency but recover it by the addition of Ca-CaM to the internal perfusion solution. X-ray diffraction data demonstrate that isolated gap junctions are gated at the cytoplasmic end by a particle of the size of a CaM lobe. We have proposed two types of CaM-driven gating: “Ca-CaM-Cork” and “CaM-Cork”. In the first, the gating involves Ca2+-induced CaM activation. In the second, the gating occurs without a [Ca2+]i rise.

Design and Development of an Automatic Unmanned Railway Level Crossing Gate

In rapidly developing countries like India, Railways are an important mode of transportation among all the people. In the railway sector, the level crossing gate plays a vital role, which should be taken into consideration. But in the level crossing gates, due to poor monitoring by the humans, many accidents are happening day-by-day. So, there is a need to develop technology to solve this issue. This paper deals with the automatic railway gate at the level crossing, which replaces the gates operated by the gatekeepers. By making it in an automatic way, can reduce the time consumption for closing the gate and also reduces human power. Streamlined the working of level crossing gate through a mini prototype model that solves this problem. Here the sensor is placed safely near the level crossing gate, which is kept at a certain distance in the railway track. Whenever the train is fastened in the railway track, the vibrations which are produced during its motion are being sensed by a sensor and it provides the necessary signal pulses to the controller which is kept at the level crossing column setup. Then the controller activates the motor, therefore the gate closes and opens automatically. Visualized the design calculation for making this setup. Hence by implementing this idea, can able to control the accidents in unmanned areas, therefore the precious human life can be saved.

Calmodulin-Cork Model of Gap Junction Channel Gating-One Molecule, Two Mechanisms.

The Calmodulin-Cork gating model is based on evidence for the direct role of calmodulin (CaM) in channel gating. Indeed, chemical gating of cell-to-cell channels is sensitive to nanomolar cytosolic calcium concentrations [Ca2+]i. Calmodulin inhibitors and inhibition of CaM expression prevent chemical gating. CaMCC, a CaM mutant with higher Ca2+-sensitivity greatly increases chemical gating sensitivity (in CaMCC the NH2-terminal EF-hand pair (res. 9–76) is replaced by the COOH-terminal pair (res. 82–148). Calmodulin colocalizes with connexins. Connexins have high-affinity CaM binding sites. Several connexin mutants paired to wild-type connexins have a high gating sensitivity that is eliminated by inhibition of CaM expression. Repeated transjunctional voltage (Vj) pulses slowly and progressively close a large number of channels by the chemical/slow gate (CaM lobe). At the single-channel level, the chemical/slow gate closes and opens slowly with on-off fluctuations. The model proposes two types of CaM-driven gating: “Ca-CaM-Cork” and “CaM-Cork”. In the first, gating involves Ca2+-induced CaM-activation. In the second, gating takes place without [Ca2+]i rise. The Ca-CaM-Cork gating is only reversed by a return of [Ca2+]i to resting values, while the CaM-Cork gating is reversed by Vj positive at the gated side.

Two-Pronged Aromatic Arginine-Mimics as Hv1 Proton Channel Inhibitors

The voltage-gated proton channel Hv1 regulates cellular pH homeostasis and the production of reactive oxygen species by the NADPH oxidase. The channel is made of two identical subunits, which gate cooperatively. Each subunit contains a voltage-sensing domain (VSD) that conducts protons and is inhibited by the arginine mimic 2-guanidinobenzimidazole (2GBI). 2GBI operates from the intracellular side and gains access to its binding site when the channel is open. The blocker must leave the binding site for the channel gate to close. We previously found that mutation F150A strongly increases the binding affinity. We now show that this increase in affinity is due to a rearrangement of the binding site allowed by the smaller residue at position 150 and use this information to design new arginine mimics with improved affinity for the non-rearranged binding site of the wild type channel. The new compounds consist of two “prongs”, an aminoimidazole ring and a fluorinated aromatic group connected by extended linkers. We find that Hv1 inhibition by the new compounds presents fast and slow binding modalities, which are affected by distinct types of perturbations of the binding site. The conservative amino acid substitution D112E in the Hv1 selectivity filter abolishes the fast component, leaving the slow component unaltered, whereas the F150A substitution affects primarily the slow component. Based on kinetic analysis of the inhibition process, we propose that the new arginine mimics are able to bind the open channel like 2GBI. However, unlike 2GBI, the new compounds become “trapped” inside the VSD when the gate closes, and they can slowly reach the binding site in the trapped conformation even from the closed state. These pharmacological properties are desirable features for the treatment of diseases associated with Hv1 gain of function.

A novel electronic gate that identifies and counts bees based on their RGB backscattered light

In this work, we present an electronic gate that aims to extract a deeper representational signal of the color characterization of the main body of an insect, namely: a) we record the backscattered light and not the extinction light as commonly done, b) a color sensor analyses backscattered light to individual RGB channels independently to grasp the melanization, microstructural and color features of the wing and body of the insects passing the gate. We present all the necessary details to reproduce the device and we analyze many insects of interest like the bee Apis mellifera and the wasp Polistes gallicus. The electronic gate is attached to the entrance of the beehive and counts foraging activity. The backscattered light intensity can quantify the size of the incoming insect and discern a drone and a worker bee from a queen bee while the color measurements aim to recognize invasive species so that the gate closes and the beekeepers are alerted.

Mechanisms of KCNE Beta Subunit Modulation of Voltage Sensing and Gating in KCNQ1 Channels

KCNQ1 (Kv7.1) channels are expressed in different tissues and exhibit different gating behaviors in these different tissues. In the heart, KCNQ1 channels are coexpressed with KCNE1 beta subunits and form slowly activating, voltage-gated potassium channels, whereas in epithelial cells KCNQ1 are coexpressed with KCNE2 or KCNE3 beta subunits and form potassium channels that appear voltage-independent. We have used voltage clamp fluorometry (VCF) to elucidate the gating mechanism in KCNQ1 channels and the effects of KCNE beta subunits on KCNQ1 gating. Voltage clamp fluorometry allows us to follow both voltage sensor movement and gate opening simultaneously, thereby better understand the relationship of voltage sensor movement and channel opening in these channels. We show that the voltage sensor S4 moves and the gate closes in KCNQ1/KCNE3 channels, but only at very negative voltages. By decoupling the voltage sensor and the gate, we show that KCNE3 mainly affects the voltage sensor and only indirectly affects the pore through the voltage-sensor-to-gate coupling. The KCNE3 seems to affect the voltage sensor S4 via an electrostatic interactions between negatively charged KCNE3 residues and positively charged S4 residues. Our data suggests that KCNE1 and KCNE3 affect different domains of KCNQ1, thereby resulting in very different modulations of KCNQ1 voltage gating. KCNE1 affects both the voltage-sensing domain and the pore-gate domain, whereas KCNE3 affects mainly the voltage-sensing domain. That different KCNE beta subunits affect different domains of KCNQ1 explains how two highly similar KCNE beta subunits have so different effects on KCNQ1 gating.

Water and a Proton Shift between a Tyrosine and a Glutamate are Two Keys to Gating in Kv1.2; A Hypothesis Based on Quantum Calculations: The Sensor is Dynamic, Based on Hydrogen Bond Rearrangements, Principally in Water Rotational Degrees of Freedom, Plus a Proton Pathway

An apparent proton pathway in the Kv1.2 K+ channel exists starting with a tyrosine (Y266, 3Lut pdb numbering) and continuing through a glutamate (E226); amino acids that would constitute several more steps can be identified, on to the H310 at the intracellular end of S4. Quantum calculations to date include four cases in which a proton shifts between Y266 and E226, the first step in the pathway, depending on electric field,. Energy differences with H+ transfer are small, ≈5 kT (open), 2 kT (closed). The calculations are, so far, approximate, but good enough to show that H+ transfer is possible, and the proton may “flicker” between the two positions. We hypothesize that proton transfer proceeds intracellularly on closing, down to H310 (the complete proposed pathway, with distances between groups in the path, can be identified); H310 affects the PVPV gate such that, with the proton at the intracellular end of this path, the gate closes. The proposed proton pathway structure resembles that in bacteriorhodopsin, where the proton transfer has been established. The water movement discussed in our other abstract appears to push a water molecule into position to assist in the first step transfer, based on calculations completed so far.

Physiology and Pathophysiology of Sodium Channel Inactivation.

Voltage-gated sodium channels are present in different tissues within the human body, predominantly nerve, muscle, and heart. The sodium channel is composed of four similar domains, each containing six transmembrane segments. Each domain can be functionally organized into a voltage-sensing region and a pore region. The sodium channel may exist in resting, activated, fast inactivated, or slow inactivated states. Upon depolarization, when the channel opens, the fast inactivation gate is in its open state. Within the time frame of milliseconds, this gate closes and blocks the channel pore from conducting any more sodium ions. Repetitive or continuous stimulations of sodium channels result in a rate-dependent decrease of sodium current. This process may continue until the channel fully shuts down. This collapse is known as slow inactivation. This chapter reviews what is known to date regarding, sodium channel inactivation with a focus on various mutations within each NaV subtypeand with clinical implications.

Prototype and numerical studies of interference characteristics of two ski-jump jets from opening spillway gates

Purpose – The purpose of this paper is to experimentally and numerically investigate the interference characteristics between two ski-jump jets on the flip bucket in a large dam spillway when two floodgates are running. Design/methodology/approach – The volume of fluid (VOF) method together with the Realizable k-ε turbulence model were used to predict the flow in two ski-jump jets and the free surface motion in a large dam spillway. The movements of the two gates were simulated using a dynamic mesh controlled by a User Defined Function (UDF). The simulations were run using the prototype dam as the field test to minimize errors due to scale effects. The simulation results are compared with field test observations. Findings – The transient flow calculations, accurately predict the two gate discharges compared to field data with the predicted ski-jump jet interference flow pattern similar to the observed shapes. The transient simulations indicate that the main reason for the deflected nappe is the larger opening difference between the two gates as the buttress side gate closes. When both gates are running, the two ski-jump jets interfere in the flip bucket and raise the jet nappe to near the buttress to form a secondary flow on this jet nappe surface. As the gate continues to close, the nappe surface continues to rise and the surface secondary flow become stronger, which deflects the nappe over the side buttress. Originality/value – A dynamic mesh is used to simulate the transient flow behavior of two prototype running gates. The transient flow simulation clarifies the hydraulics mechanism for how the two ski-jump jets interfere and deflect the nappe.

Aminocalix[4]arene: the effect of pH on the dynamics of gate and portals on the hydrophobic cavity

The pH of a solution shows a significant effect on the dynamics of the gate (formed by eight benzylic functions) and portal on the hydrophobic cavity of receptor. At pH 5.8 the gate closes and prohibits the entry of anionic guests. However, at pH 7.3 the gate opens and allows the entry of anionic guests into the hydrophobic cavity. It is the first time that anionic receptor efficiently recognizes anionic guests.

A Single Server Queue with Two Types of Customers and a Gate Mechanism

SYNOPTIC ABSTRACTWe consider a single server queue with two types(I and II) of customers in which arrivals occur according to a Poisson process and service times of customers are independent and exponentially distributed random variables. The server works according to a gated discipline. Upon arrival customers join a queue in front of a gate. Whenever all customers present at the service area have received service, the gate opens. The customers waiting for service enter the service area and the gate closes. During the service time of a type I customer, only customers of type I are admitted into the system and type II are lost to the system. When a type II customer is served, customers of both type I and type II are permitted in the system.Exact expressions for the performance characteristics, such as the total number of customers served and proportion of each type in the n-th batch are obtained. The connections between queues, branching processes and continued fractions are exploited to obtain these results. Numerical illustrations are presented.

The Importance of Ion Binding for Potassium Channel Inactivation and Recovery

Potassium channels control the flow of ions across cell membranes with gating mechanisms involving conformational changes at the intracellular gate and the selectivity filter. Opening of the intracellular gate via external stimuli (activation) results in a transient period of conduction before the selectivity filter undergoes a conformational change, which constricts the permeation pathway (inactivation). When the applied stimulus is removed and the lower gate closes (deactivation), the filter slowly resets to a conductive conformation (recovery from inactivation).

Expected waiting time in symmetric polling systems with correlated walking times

Polling systems have been extensively studied, and have found many applications. They have often been used for studying wired local area networks such as token passing rings and wireless local area networks such as bluetooth. In this contribution we relax one of the main restrictions on the statistical assumptions under which polling systems have been analyzed. Namely, we allow correlation between walking times. We consider (i) the gated regime where a gate closes whenever the server arrives at a queue. It then serves at that queue all customers who were present when the gate closes. (ii) The exhaustive regime in which the server remains at a queue till it empties. Our analysis is based on stochastic recursive equations related to branching processes with migration with a random environment. In addition to our derivation of expected waiting times for polling systems with correlated walking times, we set the foundations for computing second order statistics of the general multi-dimensional stochastic recursions.

Unusual Slow Gating of Gap Junction Channels in Oocytes Expressing Connexin32 or Its COOH-Terminus Truncated Mutant

Gap junction channels are gated by a chemical gate and two transjunctional voltage (V (j))-sensitive gates: fast and slow. Slow V (j) gate and chemical gate are believed to be the same. The slow gate closes at the negative side of V (j) and is mostly inactive without uncouplers or connexin (Cx) mutations. In contrast, our present data indicate otherwise. Oocytes expressing Cx32 were subjected to series of -100 mV V (j) pulses (12-s duration, 30-s intervals). Both peak (PK) and steady-state (SS) junctional conductances (G (j)), measured at each pulse, decreased exponentially by 50-60% (tau = approximately 1.2 min). G (j)PK dropped more dramatically, such that G (j)SS/G (j)PK increased from 0.4 to 0.6, indicating a drop in V (j) sensitivity. Less striking effects were obtained with -60 mV pulses. During recovery, G (j), measured by applying 20 mV pulses (2-s duration, 30-s intervals), slowly returned to initial values (tau = approximately 7 min). With reversal of V (j) polarity, G (j)PK briefly increased and G (j)SS/G (j)PK decreased, suggesting that V (j)-dependent hemichannel reopening is faster than hemichannel closing. Similar yet more dramatic results were obtained with COOH-terminus truncated Cx32 (Cx32-D225), a mutant believed to lack fast V (j) gating. The data indicate that the slow gate of Cx32 is active in the absence of uncouplers or mutations and displays unusual V (j) behavior. Based on previous evidence for direct calmodulin (CaM) involvement in chemical/slow gating, this may also be CaM-mediated.

Ion occlusion/deocclusion partial reactions in individual palytoxin-modified Na/K pumps.

In P-type ion-motive ATPases, transported ions approach their binding sites from one membrane surface, become buried deep within "occluded" conformations in which the sites are inaccessible from either membrane side, and are then deoccluded and released to the opposite membrane surface. This describes an alternating-gate transport mechanism, in which the pump acts like an ion channel with two gates that open and close alternately. The occluded states ensure that one gate closes before the other can open, thus preventing the large electrodiffusive ion fluxes that would otherwise quickly undo the pump's electrochemical work. High-resolution crystal structures of two conformations of the SERCA (sarcoplasmic and endoplasmic reticulum Ca(2+)) P-type ATPase, together with mutagenesis results and analyses of structural models based on homology, have begun to provide a picture of the ion coordination sites in related P-type ATPases, including the Na/K pump. However, in no P-type ATPase are the structures and mechanisms of the gates known. The marine toxin, palytoxin (PTX), is known to bind to the Na/K pump and elicit a nonselective cation leak pathway, possibly by disrupting the strict coupling between the pump's inner and outer gates, allowing them to both be open. We recently found that ion flow through PTX-modified Na/K pump-channels appears to be modulated by two gates that can be regulated by the pump's physiological ligands in a manner suggesting that gating reflects underlying ion occlusion/deocclusion partial reactions. We review that work here and provide evidence that the pore of the PTX-induced pump-channel has a diameter > 6 A.