Gap Condition Research Articles

Collisionless magnetized sheath resonance heating induced by a transverse magnetic field in low-pressure capacitive rf discharges

Abstract The mechanism of resonance heating between the gyrating electrons and the oscillating sheath induced by a small transverse magnetic field in low-pressure capacitively coupled plasmas is investigated. The gyrating electrons will coherently collide with the expanding sheath if the electron gyro-frequency coincides with half the driving frequency. These electrons will gain substantial energy from collision-less heating, which strongly enhances the electron power absorption and the plasma density at a constant driving voltage. The electron kinetics is revealed at resonant conditions by particle simulations. Our numerical results demonstrate that the relation between the magnetic field and the driving frequency determines this resonance effect. Besides, it is found that the operating pressure, electrode gap, and driving voltage all strongly affect this electron resonance mechanism. The resonance effect is more pronounced at the conditions of low pressure, large gap, and high voltage.

The Adult Perceptual Limen of Syllable Segregation in Typically Developing Paediatric Speech

Inappropriate gaps between syllables are one of the core diagnostic features of both childhood apraxia of speech and acquired apraxia of speech. However, little is known about how listeners perceive and identify inappropriate pauses between syllables (gap detection). Only one previous study has investigated the perception of inappropriate pauses between syllables in typical adult speakers and no investigations of gap detection in children's speech have been undertaken. The purpose of this research was to explore the boundaries of listener gap detection to determine at which gap length (duration) a listener can perceive that an inappropriate pause is present in child speech. Listener perception of between-syllable gaps was explored in an experimental design study using the online survey platform Qualtrics. Speech samples were collected from two typically developing children and digitally manipulated to insert gaps between syllables. Adult listeners (n = 84) were recruited and could accurately detect segregation on 80% of presentations at a duration between 100 and 125 ms and could accurately detect segregation on 90% of presentations at a duration between 125 and 150 ms. Listener musical training, gender and age were not correlated with accuracy of detection, but speech pathology training was, albeit weakly. Male speaker gender, and strong onset syllable stress were correlated with increased accuracy compared to female speaker gender and weak onset syllable stress in some gap conditions. The results contribute to our understanding of speech acceptability in CAS and other prosodic disorders and moves towards developing standardised criteria for rating syllable segregation. There may also be implications for computer and artificial intelligence understanding of child speech and automatic detection of disordered speech based on between syllable segregation.

Eye Movement Alterations in Post-COVID-19 Condition: A Proof-of-Concept Study.

There is much evidence pointing out eye movement alterations in several neurological diseases. To the best of our knowledge, this is the first video-oculography study describing potential alterations of eye movements in the post-COVID-19 condition. Visually guided saccades, memory-guided saccades, and antisaccades in horizontal axis were measured. In all visual tests, the stimulus was deployed with a gap condition. The duration of the test was between 5 and 7 min per participant. A group of patients with the post-COVID-19 condition was included in this study. Values were compared with a group () of healthy volunteers whom the SARS-CoV-2 virus had not infected. Features such as centripetal and centrifugal latencies, success rates in memory saccades, antisaccades, and blinks were computed. We found that patients with the post-COVID-19 condition had eye movement alterations mainly in centripetal latency in visually guided saccades, the success rate in memory-guided saccade test, latency in antisaccades, and its standard deviation, which suggests the involvement of frontoparietal networks. Further work is required to understand these eye movements’ alterations and their functional consequences.

Optically Isotropic Liquid Crystal Mode Templated by Nanoporous Breath Figure Membrane

AbstractIn this study, a printing‐based scalable method is proposed for the higher density of a liquid crystal (LC) nanodroplet structure suitable for the optically isotropic LC mode where the LC nanodomains are accurately templated by a nanoporous breath figure (BF) membrane. The highly porous BF polymeric template structure is reliably obtained by utilizing self‐structured packing effects of the silica nanospheres achieved by doctor blade coating. A nanocomposite film with densely packed silica nanospheres encapsulated by the UV‐crosslinked polymer matrix is made by controlling the blade coating velocity and blade gap conditions. This provides a higher LC fill‐factor condition of the optically isotropic nanodroplet LC (OI‐NDLC) mode with filling the LCs into the nanopores obtained after selective silica etching. The OI‐NDLC structure templated by the nanoporous BF membrane made with the silica nanospheres of 300 nm can effectively resolve the scattering‐induced optical loss and depolarization issues observable in the OI‐NDLC mode prepared by conventional phase separation approaches due to the sufficiently reduced LC droplet size. The structure exhibits a much‐improved light leakage level in the field‐off optically isotropic state, a higher transmittance level as the field‐induced Kerr operation, and resultant improved contrast ratio properties.

Influence of sports experience on distribution of pro-saccade reaction time under gap condition

BackgroundPrevious studies indicated that substantial individual variation exists in the distribution of pro-saccade reaction times under gap condition. To investigate the influence of sports experience on the distribution, we examined distribution of the pro-saccade reaction time under overlap and gap conditions, for the basketball club, table tennis club, and non-sporting control groups.MethodsSubjects performed pro-saccade tasks under the overlap and gap conditions, in which the intentional and reflexive disengagement of fixation are important, respectively. Under the overlap condition, the central fixation point was illuminated for a random duration of 1–3 s, then the fixation point was turned off. Just after the switch-off of the fixation point, one of the peripheral targets was illuminated for a duration of 1 s. The visual stimulus under the gap condition was almost the same as that under the overlap condition. However, only the temporal gap between the switch-off of the fixation point and the onset of the target differed between those conditions. The gap duration in the gap condition was set at 200 ms. The mean of median value of the bandwidth showing the earliest peak in the histogram was calculated for each group. Thereafter, for each subject, the bandwidth showing the earliest peak under the gap condition was defined as the criterion bandwidth (0 ms bandwidth). Based on this criterion bandwidth, the mean of the relative frequency was calculated for every 10 ms of bandwidth, for the overlap and gap conditions, in each group.ResultsUnder the overlap condition, for all subjects, the pro-saccade reaction times showed unimodal distribution. The means of the median value of the bandwidth showing the earliest peak for the basketball and table tennis groups (approximate 170 ms) were significantly earlier than that for the control group (approximate 190 ms). Under the gap condition, the distribution was bimodal for 11 of 15 subjects in the basketball group and for 5 of 15 subjects in the control group. In the table tennis group, the distribution was not bimodal but unimodal for all 15 subjects. For the basketball group, mean of the relative frequency showed bimodal distribution with approximate 120 ms and 170 ms peaks. For the table tennis and control groups, the mean of the relative frequency showed unimodal distribution with approximate 130 ms and 140ms peak, respectively.ConclusionsThe present study indicated that under the gap condition, the sports experience influenced on the distribution of the pro-saccade reaction time. The pro-saccade reaction time under the condition would show a distinct bimodal distribution for the basketball group and show a distinct and early unimodal distribution for the table tennis group. It was suggested that the physiological factor leading the group difference in the distribution was the effect of sports experience on the disengagement function of fixation.

Optimization of Design for Air Gap Sensor Using the Response Surface Methodology

In Hard Disk Drive (HDD) manufacturing, there is always a concern about the cutting defects that are caused by residual cutting chips. Only a small amount of 10 μm chips (act as the air gap) can cause the workpiece to tilt and shift from the correct position, and thus affect the dimension of the workpiece (mainly the Base HDD). For this reason, researchers adapted the adjustable micrometer as a simulation device that resembles the air gap for the design of the Air Gap Sensor Module. The design of experiments using response surface methodology will be studied to confirm the appropriate factors of the prototype. This study reports the optimization of the main factors that affect Air Gap Sensor Module condition: Air Nozzle Diameter 2.303 mm, Air Pressure 0.1 MPa, and Sampling Time 645 ms, which has a high square of the coefficient correlation (R-squared = 99.0%) with a close relationship between gap distance and air pressure. The relationship between these variables is mostly linear. The R-squared error percentage of actual value is less than 0.93% compared to predicted value. The mathematical model results and experimental values were consistent and able to predict response variables. The Air Gap Sensor Module can provide the measurement results in micron ccuracy and displays light and beep to confirm as acceptable or reject gap conditions with the uncertainty of measurement ± 0.001 mm.

Dizajn robustnog kontrolera za dvomaseni sistem povezan menjačem na osnovu hibridnog modela

Backlash is a common nonlinear phenomenon in mechanical systems, producing undesired behavior such as inaccuracies and oscillations. Instability thereby may limit the speed and position in industrial robots, automotive, and other applications. In this paper, a two-mass system connected by a gearbox is modeled as a hybrid system based on a two modes approach. First, the size of the backlash gap is assumed known; thus, when the motor and load are in negative or positive-contact, the system becomes an equivalent system (rigid body) and can be modeled as one degree of freedom, which is described as a second-order system, this mode is called Contact Mode. Second, when the motor reverses its direction, the system behaves as two separated subsystems so that each subsystem can be modeled as one degree of freedom; this mode is called Backlash Mode. A sliding mode controller (SMC) has been proposed for the above two modes in this work. Hence, two sliding mode controllers are designed, one for the contact mode to achieve tracking position performance, while the other is for the backlash mode to achieve stability. Finally, the two controllers are connected by designing a switching control mode based on the gap conditions and size. The proposed control system is tested considering two different desired references. The simulation result proved the ability and robustness of the designed SMC controllers to force the load position to track the desired reference position and overcome the nonlinearities and drawbacks of SMC, such as chattering.

Study on Impact Response of Mechanical Structures such as Instrument Panels

If an impact of flying or floating object strikes a crucial industrial facility, high-frequency waves could be applied to mechanical structures and components in the building. However, few studies have examined the effects on the critical components in facilities, including instrument panels. Therefore, this study aims to show the effect on impact response by examining the effects of gaps and friction on equipment response under high-frequency input from both vibration experiments and analysis. In the experiment, a two-degree-of-freedom system of specimens was used to simulate the machine and case of an instrument panel, and the gap and friction conditions of the machine and case models were varied to measure their respective response accelerations. In the analysis, a time history response analysis was performed using a two-degree-of-freedom system with gaps, friction, and collision springs. This paper describes that the experimental results show the relationship between impact response and steady-state response due to collision, including the analysis results using the two-degree-of-freedom system to investigate the impact response phenomena.

Linear Bayesian Approaches for Low-Oversampled Stepwise Staggered SAR Data

Staggered synthetic aperture radar (SAR) is an innovative concept to obtain an ultrawide continuous swath with fine azimuth resolution using multiple elevation beams and pulse repetition interval (PRI) variation. Conventionally, the interpolation of the nonuniform data with gaps (due to the interruption during transmission, i.e., blockage) requires a high oversampling ratio to avoid image quality degradation, which leads to increased range ambiguities and high downlink data rates. In recent years, there has been a growing interest in improving the image quality for low-oversampled staggered mode. This study suggests a new concept, stepwise staggered SAR, which employs stepwise staggered PRIs to facilitate the use of novel linear Bayesian approaches to achieve high-quality recovery of blockage in low-oversampled data. The so-called step in “stepwise” refers to a period that contains multiple constant PRIs in a PRI staggering cycle, ensuring part of the data uniformly sampled to reduce the error propagation during resampling. In addition to the no-consecutive gap condition, the stepwise PRI staggering strategy meets the requirement of no more than one gap at any location within the slant range of interest in each PRI staggering cycle, which makes it possible to easily extract prior information from the consecutive known samples on both sides of each blockage sample to realize the proposed linear Bayesian approaches. Because the prior information adapts to characteristics of backscatter, the linear Bayesian estimation has an excellent performance in blockage recovery, which has been validated by simulations with different scenarios.

A Family of Inertial Manifolds for a Class of Generalized Kirchhoff-Beam Equations

In this paper, we deal with a class of generalized Kirchhoff-Beam equations. At first, we take advantage of Hadamard’s graph to get the equivalent form of the original equations. Then, the inertial manifolds are proved by using spectral gap condition. We gain main result is that the family of inertial manifolds are established under the proper assumptions of nonlinear terms M(s) and N(s).

Exact controllability to eigensolutions of the bilinear heat equation on compact networks

<p style='text-indent:20px;'>Partial differential equations on networks have been widely investigated in the last decades in view of their application to quantum mechanics (Schrödinger type equations) or to the analysis of flexible structures (wave type equations). Nevertheless, very few results are available for diffusive models despite an increasing demand arising from life sciences such as neurobiology. This paper analyzes the controllability properties of the heat equation on a compact network under the action of a single input bilinear control.</p><p style='text-indent:20px;'>By adapting a recent method due to [F. Alabau-Boussouira, P. Cannarsa, C. Urbani, <i>Exact controllability to eigensolutions for evolution equations of parabolic type via bilinear control</i>, arXiv: 1811.08806], an exact controllability result to the eigensolutions of the uncontrolled problem is obtained in this work. A crucial step has been the construction of a suitable biorthogonal family under a non-uniform gap condition of the eigenvalues of the Laplacian on a graph. Application to star graphs and tadpole graphs are included.</p>

A Family of Inertial Manifolds for a Class of Asymmetrically Coupled Generalized Higher-Order Kirchhoff Equations

In this paper, we study the inertial manifolds for a class of asymmetrically coupled generalized Higher-order Kirchhoff equations. Under appropriate assumptions, we firstly exist Hadamard’s graph transformation method to structure a graph norm of a Lipschitz continuous function, then we prove the existence of a family of inertial manifolds by showing that the spectral gap condition is true.

A roadmap for bootstrapping critical gauge theories: decoupling operators of conformal field theories in $d>2$ dimensions

We propose a roadmap for bootstrapping conformal field theories (CFTs) described by gauge theories in dimensions d>2d>2. In particular, we provide a simple and workable answer to the question of how to detect the gauge group in the bootstrap calculation. Our recipe is based on the notion of decoupling operator, which has a simple (gauge) group theoretical origin, and is reminiscent of the null operator of 2d2d Wess-Zumino-Witten CFTs in higher dimensions. Using the decoupling operator we can efficiently detect the rank (i.e. color number) of gauge groups, e.g., by imposing gap conditions in the CFT spectrum. We also discuss the physics of the equation of motion, which has interesting consequences in the CFT spectrum as well. As an application of our recipes, we study a prototypical critical gauge theory, namely the scalar QED which has a U(1)U(1) gauge field interacting with critical bosons. We show that the scalar QED can be solved by conformal bootstrap, namely we have obtained its kinks and islands in both d=3d=3 and d=2+\epsilond=2+ϵ dimensions.

Effect of Photoconductivity Precursor Volume on Structural, Physical, Electrical and Optical Properties of Thin Layers of Cadmium Oxide (CdO) Nanostructures Produced Using Spray Pyrolysis Technique

Thin layers of Cadmium Oxide (CdO) are produced over glassy substrate by spray pyrolysis technique with precursor volumes of 50, 75 and 100 (ml). FESEM images of samples show the formation of nanometric structures and structural characterization of them resulted from XRD spectroscopy indicate the formation of cubic polycrystalline structure in growing layers with preferred direction of (111). Evaluating the optical properties of samples show that optical band gap of layers is reduced from 3.6 to 3.4 (eV) by increasing the precursor volume and the optical absorption coefficient of samples is in UV region at about 105 (cm-1). Data analysis indicates that the produced sample in volume of 100 mL has the smallest penetration depth (smaller than 200 nm) in UV region. On the other hand, thin layers of Cadmium Oxide (CdO) with various volumes of Cadmium acetate solution (40, 50 and 70 ml) were deposited using spray pyrolysis technique over a glassy substrate. Samples were investigated using FESEM images, XRD and UV-Vis spectra as well as I-V characteristic. It was found that all samples were grew up with polycrystalline nanostructures along the preferred direction of (002). In addition, it was found that grew up sample in the volume of 50 (ml) are of optimum photoconductivity condition in visible range regarding optimum structural (largest crystallite size and lowest crystallite defect density) and optical (smallest band gap and highest light absorption) conditions.

Saccadic Eye Movements in Elderly Depressed Patients With Suicidal Behaviors: An Exploratory Eye-Tracking Study.

Suicidal behaviors (SBs) are often associated with impaired performance on neuropsychological executive functioning (EF) measures that encourage the development of more specific and reliable tools. Recent evidence could suggest that saccadic movement using eye tracking can provide reliable information on EF in depressive elderly. The aim of this study was to describe oculomotor performances in elderly depressed patients with SB. To achieve this aim, we compared saccadic eye movement (SEM) performances in elderly depressed patients (N = 24) with SB and with no SB in prosaccade (PS) and antisaccade (AS) tasks under the gap, step, and overlap conditions. All participants also underwent a complete neuropsychological battery. Performances were impaired in patients with SB who exhibited less corrected AS errors and longer time to correct them than patients with no SB. Moreover, both groups had a similar performance for PS latencies and correct AS. These preliminary results suggested higher cognitive inflexibility in suicidal patients compared to non-suicidal. This inflexibility may explain the difficulty of the depressed elderly in generating solutions to the resurgence of suicidal ideation (SI) to respond adequately to stressful environments. The assessment of eye movement parameters in depressed elderly patients may be a first step in identifying high-risk patients for suicide.

Modeling and Simulation of Human Body Heat Transfer System Based on Air Space Values in 3D Clothing Model.

Comfort can be considered as subjective feeling, which could be affected by the external ambient, by the physical activity, and by clothing. Considering the human body heat transfer system, it mainly depends on various parameters including clothing materials, external and internal environment, etc. The purpose of the current paper is to study and establish a quantitative relationship between one of the clothing parameters, ease allowance (air gap values) and the heat transfer through the human body to clothing materials and then to the environment. The study considered clothing which is integrated with the 3D ease allowance from the anthropometric and morphological data. Such incorporating of the clothing’s 3D ease control was essential to properly manage the air space between the body and the proposed clothing thermal regulation model. In the context of thermal comfort, a clothing system consisting of the human body, an ease allowance under clothing, a layer of textile materials, and a peripheral layer adjacent to the textile material was used. For the complete system, the heat transfer from the skin to the environment, which is influenced by thermoregulation of the human body, air gap, tissue, and environmental conditions were also considered. To model and predict the heat transfer between the human body and the temperature of skin and clothes, a 3D adaptive garment which could be adjusted with ease allowance was used. In the paper, a thermoregulatory model was developed and proposed to predict the temperature and heat within clothing material, skin, and air space. Based on the result, in general the main difference in the temperature of clothing and skin from segment to segment is due to the uneven distribution of air layers under the clothing.

Sugar maple (Acer saccharum) Seedling Bank Response to Storm Disturbance and Single Tree Selection Harvest in the Southern Keweenaw Peninsula, Michigan

This case study seeks to fill a critical knowledge gap regarding how natural wind disturbance affects stand and seedling bank diversity in mixed northern hardwood forests managed by single tree selection harvest methods. Contemporary timber harvests on state managed lands in Michigan's Upper Peninsula employ single tree selection cutting methods to promote more complex age structure in second growth stands dominated by sugar maple (Acer saccharum). However, concern exists that single tree selection harvest may result in lowered compositional diversity of seedlings as the low light conditions of small dispersed gaps exclude less shade tolerant species from gap regeneration. In July 2016 severe thunderstorms with winds in excess of 145 km/h (90 mph) caused extensive tree fall and canopy gap creation in second growth mixed northern hardwood forests in the southern Keweenaw Peninsula. We measured the species composition of overstory tree mortality and understory seedling regeneration in 14 storm gaps created in stands with and without previous single tree selection harvest. Storm gaps ranged in size from 125 to 1100 m2. American basswood (Tilia americana) was disproportionately wind-thrown. Robust seedling regeneration was released in all storm gaps, with sugar maple comprising more than 75% of mean seedling abundance, regardless of previous single tree selection harvest. Sugar maple and ironwood (Ostrya virginiana) comprised 80% of sapling abundance. Results indicate single tree selection of mixed northern hardwood stands does not exacerbate, but rather emulates, dense sugar maple regeneration found on unmanaged second growth sites.

Beech and hornbeam dominate oak 20 years after the creation of storm-induced gaps

Oak (Quercus petraea (Matt.) Liebl. and Quercus robur L. grouped), European beech (Fagus sylvatica L.) and hornbeam (Carpinus betulus L.) are three major species of western and central European forests. When conditions are suitable for the three species, silvicultural management often favours oak because of its greater economic interest. Forest managers know that beech and hornbeam are strong competitors for oak during the regeneration phase, but the conditions that influence the relative success of the regeneration of the three species growing in mixture are still poorly characterised. The natural regeneration of the three species 20 years after canopy openings was studied based on 108 study sites established in 2001 in French forests impacted by the windstorms Lothar and Martin in 1999. In spring and summer 2018 and 2019, all saplings over 0.1 m in height were counted, species were identified and diameter at breast height (DBH) was measured for all saplings over 1.30 m. The height of the saplings with the highest and median DBH in each plot was recorded for each species. Mixed models were used to analyse the combined effects of former stand type, distance from the edge of the gap and soil conditions on species presence, sapling abundance, DBH and height. The modelling approach highlighted the preponderant role of the initial seed rain on the presence and sapling density of the three species compared to interspecific competition or distance from the edge. The two latter factors had a secondary effect on sapling DBH and height. Beech and hornbeam saplings were more abundant than oak saplings regardless of soil conditions (on average, 3097, 3063 and 344 saplings ha−1, respectively), suggesting a strong competitive ability of these two species. Oak was present on 22% (43% for hornbeam and 68% for beech) of the studied plots, at a low density but with a height and DBH similar to that of beech or hornbeam. This result highlights the high dissemination capacity of beech and hornbeam, which prevents the establishment of a stand dominated by oak. When seeking to obtain oak-dominated stands in the lowlands of Europe, the abundance of beech and hornbeam can be a limiting factor that could lead to the disappearance of oak from large areas if no silvicultural operations are performed to promote it.

Three‐Partner Symbiosis among Legumes, Mycorrhizae, and N‐Fixing Bacteria Changes with Light and Soil Nitrogen Conditions

Photo 1. A canopy gap at La Selva Biological Station in Costa Rica, created from treefalls during a storm. Seedlings planted under gap conditions were located here, and seedlings planted under understory conditions were in adjacent intact forest. Photo credit: Orlando Vargas Ramirez. Photo 2. Half of the seedlings planted in the gap were kept under a shade cloth to mimic understory light conditions (depicted in panel A). This experimental design allowed us to explore the effects of light alone on the tripartite symbiosis, as it is only one of many factors that vary between gaps and intact forest. Panel B is a top-down view of one of the experimental plots. There are two seedlings of each of the three legume species used in the experiment: (from top to bottom) Stryphnodendron microstachyum, Zygia longifolia, and Pentaclethra macroloba. Photo credit: Lindsay McCulloch. Photo 3. One mm of a root colonized by arbuscular mycorrhizal fungi, stained, and observed under 200× magnification. 100 such images were observed for each seedling to estimate the percentage of each seedling’s root system that was colonized by arbuscular mycorrhizal fungi. This metric was a proxy for carbon investment in arbuscular mycorrhizal fungi by the seedling. Photo credit: Nikayla Ficano. These photographs illustrate the article “Tripartite legume–rhizobia–mycorrhizae relationship is influenced by light and soil nitrogen in Neotropical canopy gaps” by Nikayla Ficano, Stephen Porder, and Lindsay A. McCulloch published in Ecology. https://doi.org/10.1002/ecy.3489.

Optimality of spectral clustering in the Gaussian mixture model

Spectral clustering is one of the most popular algorithms to group high- dimensional data. It is easy to implement and computationally efficient. Despite its popularity and successful applications, its theoretical properties have not been fully understood. In this paper, we show that spectral clustering is minimax optimal in the Gaussian mixture model with isotropic covariance matrix, when the number of clusters is fixed and the signal-to-noise ratio is large enough. Spectral gap conditions are widely assumed in the literature to analyze spectral clustering. On the contrary, these conditions are not needed to establish optimality of spectral clustering in this paper.