Effects Of Gates Research Articles

Correspondences Between Parameters in a Reaction-Diffusion Model and Connexin Functions During Zebrafish Stripe Formation

Different diffusivities among interacting substances actualize the potential instability of a system. When these elicited instabilities manifest as forms of spatial periodicity, they are called Turing patterns. Simulations using general reaction-diffusion (RD) models demonstrate that pigment patterns on the body trunk of growing fish follow a Turing pattern. Laser ablation experiments performed on zebrafish reveal apparent interactions among pigment cells, which allow for a three-component RD model to be derived. However, the underlying molecular mechanisms responsible for Turing pattern formation in this system remain unknown. A zebrafish mutant with a spotted pattern was found to have a defect in Connexin41.8 (Cx41.8) which, together with Cx39.4, exists in pigment cells and controls pattern formation. Here, molecular-level evidence derived from connexin analyses is linked to the interactions among pigment cells described in previous RD modeling. Channels on pigment cells are generalized as “gates,” and the effects of respective gates were deduced. The model uses partial differential equations (PDEs) to enable numerical and mathematical analyses of characteristics observed in the experiments. Furthermore, the improved PDE model, including nonlinear reaction terms, enables the consideration of the behavior of components realistically.

More physical understanding of current characteristics of tunneling field-effect transistor leveraged by gate positions and properties through dual-gate and gate-all-around structuring

In this work, a tunneling field-effect transistor (TFET) in the structure that can maximize the electrostatic effects in determining its electrical performances is optimally designed and characterized. The featured device structure includes gate-all-around (GAA) channel and dual gates (DuGs) identified as control gate (CG) and adjust gate (AG), respectively. Not along with the design tasks, more fundamental studies on the effects of respective gates on device performances are sought. It has been found that the relatively different vicinities of the DuGs to source and drain junctions have differentiable dominances in controlling the primary direct-current (DC) parameters of the TFET including threshold voltage (Vth), on-state current (Ion), subthreshold swing (S), and on/off current ratio (Ion/Ioff). For the systematic study, four different cases have been presumably schemed giving the degree of freedom in gate workfunctions and inter-gate connectivity. It has been found that the CG at the source side more effectively modulates Vth, Ioff, and S, while the AG at the drain side shows the higher controllability over Ion and Ion/Ioff of the TFET. An optimally designed GAA DuG demonstrated Ion/Ioff > 1011 along with a small S of 14.6 mV/dec, which supports the strong potential of the GAA DuG TFET in the low-power applications.

Landau level phases in bilayer graphene under pressure at charge neutrality

Bilayer graphene in a magnetic field hosts a variety of ordered phases built from eight Landau levels close in energy to the neutrality point. These levels are characterized by orbital $n=0,1$, valley $\xi=+,-$ and spin $\sigma=\uparrow,\downarrow$; their relative energies depend strongly on the Coulomb interaction, magnetic field, and interlayer bias. We treat interactions at the Hartree-Fock level, including the effects of metallic gates, layer separation, spatial extent of the $p_z$ orbitals, all Slonczewski-Weiss-McClure tight-binding parameters, and pressure. We obtain the ground state as function of the applied magnetic field, bias, and pressure. The gates, layer separation and extent of the $p_z$ orbitals weaken the Coulomb interaction at different length scales; these effects distort the phase diagram but do not change its topology. However, previously-predicted continuous transitions become discontinuous when all tight-binding parameters are included nonperturbatively. We find that pressure increases the importance of the noninteracting scale with respect to the Coulomb energy, which drives phase transitions to occur at lower fields. This brings two orbitally polarized states not yet predicted or observed into the experimentally accessible region of the phase diagram, in addition to previously-identified valley-, spin-, and partially orbitally polarized states.

The history of the sedimentation processes and heavy metal pollution in the Central Danube Delta (Romania)

Abstract The aim of this study was to investigate the effects of the Iron Gates (IG) hydroelectric power station on the Danube Delta sediment dynamics, and to assess the heavy metal concentrations and pollution in a typical Central Danube Deltaic lake. Eight sediment cores were analysed. The total 210Pb content was measured with 210Po using alpha spectrometry, and the supported 210Pb (226Ra) and 137Cs were measured by gamma spectrometry. The age depth model was derived by applying the 210Pb dating method, and for the calculation of the ages and the sedimentation rates the CRS model was used. The sedimentation rates can be divided into four periods:1940–1972, 1972–1980, 1972–1989 and 1989–2013. In the case of Lake Iacob in the first period, the average sedimentation rate was 0.418 g/cm2y, while in the second it slowly decreased to 0.376 g/cm2y. In the third period, the sedimentation fell to 0.209 g/cm2y, which means the retention of 27.3% of the sediment by the IG dam. In the case of Lake Isac the changes were more visible: in the first period the average sedimentation rate was 0.446 g/cm2y, while in the second it decreased to 0.197 g/cm2y, which means a 42.35% retention of sediment. In the last period, in both cases, a high increase in the sedimentation rate is shown: 0.677 g/cm2y for Lake Iacob and 0.715 g/cm2y for Lake Isac. The heavy-metal concentrations for As, Co, Cr and Ni show decreasing and Hg increasing tendencies, while Cd and Pb show constant values of 310 ± 12 ppb and 9 ± 1 ppm respectively.

Modelling of enterobacterial loads to the Baie des Veys (Normandy, France).

The Baie des Veys (Normandy, France) has abundant stocks of shellfish (oyster and cockle farms). Water quality in the bay is affected by pollutant inputs from a 3500 km2 watershed and notably occasional episodes of contamination by faecal coliforms. In order to characterise enterobacterial loads and develop a plan of action to improve the quality of seawater and shellfish in the bay, a two-stage modelling procedure was adopted. This focused on Escherichia coli and included a catchment model describing the E. coli releases, and the transport and die-off of this bacteria up to the coast. The output from this model then served as input for a marine model used to determine the concentration of E. coli in seawater. A total 60 scenarios were tested, including different wind, tidal, rainfall and temperature conditions and accidental pollution events, for both current situations and future scenarios. The modelling results highlighted the impact of rainfall on E. coli loadings to the sea, as well as the effects of sluice gates and tidal cycles, which dictated the use of an hourly timescale for the modelling process. The coupled models also made it possible to identify the origin of these enterobacteria as found in shellfish harvesting areas, both in terms of the contributing watercourses and the sources of contamination of those watercourses. The tool can accordingly be used to optimise remedial action.

Mixed effects of gating subterranean habitat on bats: A review

ABSTRACTCaves and abandoned mines, roosting environments for many bat species including subterranean obligates, are under human pressure (e.g., recreation) and pose threats to humans. Gating entrances of these subterranean features prevents human entry while protecting habitat for bats. However, bat response to these gates is not well understood and no comprehensive synthesis with species‐specific recommendations on protection measures for bat roosts exists. We reviewed literature on effects of gating subterranean habitat on bats and roost microclimate and found 22 studies and reports from North America, Australia, Europe, and Asia. Ten studies examined effects of gating on bat use, 9 described behavioral responses to gates, and 5 presented effects of gates on roost microclimate. Older gate designs (1950–1970), such as cement walls or iron doors, negatively affected bat use and roost microclimate, but responses to modern (1970s to present), bat‐compatible gate designs varied. Short‐term responses of bats to bat‐compatible gates were negative and included increases in energetically expensive flight behaviors. Although long‐term responses included a mix of population and species trends, we attribute these mixed responses in part to differences in flight agility among species. Bats with moderate to high agility (low wing loading, broad call bandwidths) adjust to gates, but species with low agility (high wing loading and narrow call bandwidths) may abandon sites after gating. Other factors including bat density in roosts and size of the cave or mine entrance also affect acceptance of gates and should be considered in gate design. Current gate designs are adequate for most species. Based on available literature, we recommend use of bat‐compatible gates with horizontal bar spacing of 14.6 cm, bar types that offer high structural rigidity in areas where vandalism is likely, and periodic monitoring of gates to ensure they remain in good condition. © 2017 The Wildlife Society.

Quantum transport in graphene Hall bars: Effects of side gates

Quantum electron transport in side-gated graphene Hall bars is investigated in the presence of quantizing external magnetic fields. The asymmetric potential of four side-gates distorts the otherwise flat bands of the relativistic Landau levels, and creates new propagating states in the Landau spectrum (i.e. snake states). The existence of these new states leads to an interesting modification of the bend and Hall resistances, with new quantizing plateaus appearing in close proximity of the Landau levels. The electron guiding in this system can be understood by studying the current density profiles of the incoming and outgoing modes. From the fact that guided electrons fully transmit without any backscattering (similarly to edge states), we are able to analytically predict the values of the quantized resistances, and they match the resistance data we obtain with our numerical (tight-binding) method. These insights in the electron guiding will be useful in predicting the resistances for other side-gate configurations, and possibly in other system geometries, as long as there is no backscattering of the guided states.

Modified tide gate management for enhancing instream habitat for native fish upstream of the saline limit

Tide and flood gates are used widely throughout the world to facilitate drainage of lowland areas and provide flood protection to valuable agricultural land and human infrastructure. However, these structures can impact on aquatic communities by disrupting connectivity and altering physical habitat conditions. Complete removal is rarely feasible in the short-term because of the competing flood mitigation and land use interests. However, in many cases it is likely that the structure and/or its operation can be modified to enhance connectivity for migratory species and reduce the severity of impacts on instream habitats.This study describes the results of a short-term trial investigating the effects of modified tide gate management on instream habitat and fish communities in a small tidal stream in the North Island of New Zealand. The study site was located upstream of the saline limit and thus does not directly address this potential limitation on managing the effects of some tide gates. The main objective of the study was to understand whether improvements in tidal flushing could mitigate the negative effects of tide gates on upstream habitats, thus improving their suitability for native fish communities.The trial demonstrated that in impacted lowland river reaches, the reintroduction of limited tidal exchange upstream of tide gates reduced negative impacts on instream habitat by restoring hydrological variability, increasing minimum dissolved oxygen concentrations and potentially also reducing water temperatures. However, it was also shown that the recovery may not be uniform and can be dependent on interactions with other stressors. The trial illustrated the potential for using modified tide gate management to mitigate the environmental effects associated with their operation, and to restore habitat conditions so that they are more favourable for the persistence of native fish species.

Comparison of Strategies for Enhancing Energy Capture and Reducing Loads Using LIDAR and Feedforward Control

In this paper, we investigate strategies to enhance turbine energy capture and mitigate fatigue loads using pulsed light detection and ranging (LIDAR) system-enabled torque control strategies. To enhance energy capture when a turbine is operating below rated wind speed, three advanced LIDAR-enabled torque controllers are proposed: the disturbance tracking control (DTC) augmented with LIDAR, the optimally tracking rotor (OTR) control augmented with LIDAR, and LIDAR-based preview control. The DTC with LIDAR and LIDAR-based preview control is combined with a linear quadratic regulator in the feedback path, while OTR is a strategy adapted from a quadratic <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">k</i> Ω <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> torque feedback control. These control strategies are simulated in turbulent wind files and their performance is compared against the baseline <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">k</i> Ω <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> control scheme. We also consider the effects of different LIDAR update rates and range gates. It is shown that LIDAR-enabled controllers have only a small effect on energy capture at the cost of increased control action and low-speed shaft torque load. However, when considering a combination of fatigue load mitigation, power capture enhancement, and control authority requirements, the LIDAR-enabled preview controller outperforms the baseline <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">k</i> Ω <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> controller.

이중게이트 MOSFET의 스켈링 이론에 대한 문턱전압이하 스윙분석

본 연구에서는 이중게이트 MOSFET에서 스켈링 이론에 대한 문턱전압이하 스윙을 분석하였다. 포아송방정식의 해석학적 전위분포를 구하기 위하여 가우스 전하분포를 이용하였다. 문턱전압이하 스윙의 저하와 같은 단채널 효과를 분석하기 위하여 스켈링이론이 사용되었으며 이중게이트 MOSFET의 특성상 두 개의 게이트 효과를 포함하기 위하여 일반적인 스켈링 이론을 수정하였다. 게이트길이에 대한 스켈링인자가 일반적인 스켈링인자의 1/2일 때 문턱전압이하 스윙의 저하현상이 매우 빠르게 감소하였으며 가우스함수의 이온주입범위 및 분포편차도 문턱전압이하 스윙에 영향을 미치는 것을 알았다. This study has presented the analysis of subthreshold swings based on scaling theory for double gate MOSFET. To solve the analytical potential distribution of Poisson's equation, we use Gaussian function to charge distribution. The scaling theory has been used to analyze short channel effect such as subthreshold swing degradation. These scaling factors for gate length, oxide thickness and channel thickness has been modified with the general scaling theory to include effects of double gates. We know subthreshold swing degradation is rapidly reduced when scaling factor of gate length is half of general scaling factor, and parameters such as projected range and standard projected deviation have greatly influenced on subthreshold swings.

Effects of Gates on the Nighttime Use of Mines by Bats in Northern Idaho

Bat gates are installed at the entrances of abandoned mines to protect bat habitat and ensure human safety; however, the response of bats to gates has received little study. Using mist nets and video surveys, we compared use of abandoned mines in northern Idaho by bats (species, entries, and behavior), before and after installation of bat gates, with bat use at ungated reference mines. The number of bat species using mines and the number of individual bats entering mines declined significantly at mines where gates were installed, but not at ungated mines. In addition, 3 of 7 behaviors recorded (entry looping, flying in front, and entry retreating) changed noticeably in frequency of occurrence at experimental mines after being gated, but these changes were not statistically significant. Our data suggest that, in the short-term, bat gates decreased the use of mines by bats and changed their behavior at the abandoned mines we studied. However, our results should be viewed cautiously, given our small sample sizes.

Nanostructures in p-GaAs with improved tunability

A nanofabrication technique is presented which enables the fabrication of highly tunable devices on p-type, C-doped GaAs/AlGaAs heterostructures containing shallow two-dimensional hole systems. The high tunability of these structures is provided by the complementary electrostatic effects of intrinsic in-plane gates and evaporated metallic top-gates. Quantum point contacts fabricated with this technique were tested by electrical conductance spectroscopy.

Effects of protective gates at concentrate feed stations on behaviour and production in dairy cows: A brief note

Concentrate feed stations for dairy cows improve feeding management allowing frequent individual feeding. Concentrates are highly valued by cows and then a cause for competition and aggression. The production and cow welfare may be compromised because of frequent displacements of cows visiting the feed station. A comparison was made between two concentrate feeding stations with two groups of 20 cows each in a change-over experiment lasting for 18 weeks. One feeding stations was equipped with protective gates, which closed while the cow in the feeding station was fed concentrates which eliminated displacement of this cow. No difference in milk production was obtained. The number of visits to the feeding station with protective gates was fewer than to the control (12.7 versus 15.9; P < 0.001) as was the number of unrewarded visits (without feed supply) (3.7 versus 5.3; P < 0.01). The number of aggressions directed towards cows in the concentrate feeding station was reduced by 65% in the feed station with protective gates as was the number of displacements of cows from the concentrate feeding station by 67%. It was concluded that the protective gates reduced competition and made concentrate feeding more efficient.

Correlated product distributions from ketene dissociation measured by dc sliced ion imaging

Speed distributions of spectroscopically selected CO photoproducts of 308 nm ketene photodissociation have been measured by dc sliced ion imaging. Structured speed distributions are observed that match the clumps and gaps in the singlet CH2 rotational density of states. The effects of finite time gates in sliced ion imaging are important for the accurate treatment of quasicontinuous velocity distributions extending into the thickly sliced and fully projected regime, and an inversion algorithm has been implemented for the special case of isotropic fragmentation. With accurate velocity calibration and careful treatment of the velocity resolution, the new method allows us to characterize the coincident rotational state distribution of CH2 states as a smoothly varying deviation from an unbiased phase space theory (PST) limit, similar to a linear-surprisal analysis. High-energy rotational states of CH2 are underrepresented compared to PST in coincidence with all detected CO rotational states. There is no evidence for suppression of the fastest channels, as had been reported in two previous studies of this system by other techniques. The relative contributions of ground and first vibrationally excited singlet CH2 states in coincidence with selected rotational states of CO (upsilon=0) are well resolved and in remarkably good agreement with PST, despite large deviations from the PST rotational distributions in the CH2 fragments. At 308 nm, the singlet CH2 (upsilon2=0) and (upsilon2=1) channels are 2350 and 1000 cm(-1) above their respective thresholds. The observed vibrational branching is consistent with saturation at increasing energies of the energy-dependent suppression of rates with respect to the PST limit, attributed to a tightening variational transition state.

The effect of gates on cave entry by swarming bats

Temperate bats make extensive use of caves and mines as nursery roosts, swarming sites and hibernacula. For a variety of reasons, the entrances to many sites have been modified in the past to restrict human access. Early barrier design often gave little regard to bats, leading to massive population declines in many nursery and hibernation sites. Free access to bats has become an increasingly important design feature, as the damaging effects of early gates were recognised. However, given the large number of gates that have been constructed, relatively few studies have looked at either the short or long-term effects of gates on bat behaviour and population sizes. Even fewer studies have examined specifically the effects of different gate designs. We have looked at the immediate effects of gates on the behaviour of swarming bats as they entered a natural cave. Three gates were tested, all with vertical grille spacings of 750 mm, but with horizontal spacings of 150, 130 or 100 mm. The gate with 150 mm spacings had no significant effect on the behaviour of the bats (predominantly Myotis nattereri). Gates with both 130 mm and 100 mm spacing caused a significant and substantial increase in the number of bats aborting their first and often subsequent attempts to enter the cave. The consequences to swarming behaviour and long-term use of the site by bats are unknown, but we suggest that following the precautionary principle, the minimum spacing between horizontal bars in gates should be 150 mm.

Local Gating of Carbon Nanotubes

Local effects of multiple electrostatic gates placed beneath carbon nanotubes grown by chemical vapor deposition (CVD) are reported. Single-walled carbon nanotubes were grown by CVD from Fe catalyst islands across thin Mo “finger gates” (∼150 nm × 10 nm). Prior to tube growth, several finger gates were patterned lithographically and subsequently coated with a patterned high-κ dielectric using low-temperature atomic layer deposition. Transport measurements demonstrate that local finger gates have an effect that is distinct from that of a global backgate.

Influence of gate oxide thickness on Sc 2O 3/GaN MOSFETs

The influence of Sc 2O 3 gate dielectric thickness and of gate length of GaN metal–oxide–semiconductor field effect transistor (MOSFETs) on saturation current, gate current, gate breakdown voltage and threshold voltage were examined using a drift–diffusion model. The threshold voltage was directly proportional to Sc 2O 3 thickness and only modestly dependent on dielectric thickness. The saturation drain current was <10 −2 A μm −1 for all gate lengths in the range 0.5–1.0 μm devices with oxide thickness < 800 Å. Gate current is <10 −6 A μm −1 at 300 K even at 100 V gate bias for 0.5 μm gate lengths and dielectric thicknesses < 800 Å. The gate breakdown voltage was directly proportional to dielectric thickness. The Sc 2O 3 also performs as an effective surface passivation layer, mitigating the effects of virtual gates created in the gate–drain region by surface states.

Effects of metallic gates on ac measurements of the quantum hall resistance

Using a sample with a split back-gate, a linear frequency dependence of the ac quantum Hall resistance was observed. The frequency coefficient, which is due to dielectric losses produced by leakage current between the 2DEG and the back-gates, can be turned from a positive to a negative values by increasing the back-gate voltage. More interestingly, by removing theses back-gates, the losses can be considerably reduced leading to a residual frequency coefficient on the order of (0.03+-0.03) ppm/kHz. Moreover, at 1 kHz, an extremely flat plateau was observed over a magnetic field range of 1.4 T. These results clearly indicate that the audio frequency dependence of the QHR is to a large extend related to the measurement apparatus and does not originate from the physical transport properties of the 2DEG.

Effects of local gates on the electrical transport of single-walled carbon nanotubes

We have studied the effect of local gates on the electrical transport properties of single-walled carbon nanotubes (SWNT). The local gate have been incorporated into individual SWNT by depositing Al top gate in between Au/Ti electrodes. Noticeable increase of resistance was observed after the deposition of the Al top gates, implying that the Al top gate acted as a barrier for electrical conduction.

The barrier attenuation of garden fences

A study has been undertaken of the barrier attenuation produced by 40 different finite garden fences shielding suburban homes from traffic noise. Two alternative techniques of measuring barrier attenuation were used and an empirical relationship between the results is obtained. The attenuation measured in terms of L 1 , L 10 or L eq generally agrees within ± 1 dB(A) for a given barrier. Similarly constructed fences can produce different attenuations, depending on their surroundings. The effects of unshielded ends, open gates and vegetation are considered. It is postulated that buildings reflect back sound, the effect depending on building size and distance from the fence. A reasonable trend is obtained for brick barriers; however, the wooden fence results may be obscured by sound leakage through the fence.