scholarly journals Is a Simple Sensorimotor Reaction Really Simple?

2020 ◽  
Author(s):  
Alexey A. Kulakov
Keyword(s):  
Relaxation Time ◽  
Waiting Time ◽  
Complex Structure ◽  
Time Interval ◽  
Previous Response ◽  
A Value ◽  
Corneal Reflex ◽  
Sensorimotor Reaction ◽  
The Moment ◽  
Made In

AbstractThe simple sensorimotor reaction (SSR) is widely used in psychophysiological research. It was previously shown, that the SSR latency is not constant. We studied changes in the SSR latency as a function of the waiting time from the moment of the previous response to the moment of the start of the stimulation. We performed the stimulation using light, sound and air impulse. As a response, we used a “labial sound”, a finger touch and blinking of the eyes. In all cases, where the objects of the study were humans, the SSR latency had constant and variable components. The constant SSR component was the shortest in response to closing the eyes to sound (120 ms). For “lip reaction” and finger response to sound it was 174–178 ms and 178–182 ms, respectively, but for “lip reaction” and finger response to light it was 220–226 ms. The variable SSR component represented exponential latency decay with an increase in the waiting time interval. In this case, the decay consisted of at least two components, with an apparent relaxation time in the range 30–150 ms and 600–1300 ms. Alternating stimulation of paired organs of the reception or alternating fingers reduced the apparent relaxation time of the SSR latency decay. Moreover, the latency of the human corneal reflex during eye stimulation with an air pulse also had the latency decay with three components of apparent relaxation time 9.5, 68.2 and 1,086 ms and the constant latency of 34.2 ms.The latency of the corneal reflex in a young cat was constant and had a value of 14.6 ms. Thus, it has been shown, that the SSR latency has a complex structure and, like any conditioned reflex, is strongly influenced by the cortex. We believe that a choice is made in the centers for analysis of receiving signals from reception organs and centers sending signals to reacting organs, i.e. essentially, the SSR is also a choice reaction.

scholarly journals Period-Life of a Branching Process with Migration and Continuous Time

Mathematics ◽  
2021 ◽  
Vol 9 (8) ◽  
pp. 868
Author(s):  
Khrystyna Prysyazhnyk ◽  
Iryna Bazylevych ◽  
Ludmila Mitkova ◽  
Iryna Ivanochko
Keyword(s):  
Random Process ◽  
Generating Function ◽  
Continuous Time ◽  
Branching Process ◽  
Probability Generating Function ◽  
Time Interval ◽  
The Moment ◽  
First Time ◽  
Critical Branching Process ◽  
Number Of Particles

The homogeneous branching process with migration and continuous time is considered. We investigated the distribution of the period-life τ, i.e., the length of the time interval between the moment when the process is initiated by a positive number of particles and the moment when there are no individuals in the population for the first time. The probability generating function of the random process, which describes the behavior of the process within the period-life, was obtained. The boundary theorem for the period-life of the subcritical or critical branching process with migration was found.

The asymptotic stage of longitudinal turbulent dispersion within a tube

1977 ◽  
Vol 80 (2) ◽  
pp. 293-303 ◽  
Author(s):  
R. Dewey ◽  
Paul J. Sullivan
Keyword(s):  
Turbulent Flows ◽  
Friction Velocity ◽  
Turbulent Dispersion ◽  
Time Interval ◽  
Longitudinal Diffusion ◽  
A Value ◽  
Discharge Velocity ◽  
Concentration Curves ◽  
Temporal Growth Rate ◽  
Short Times

This paper describes an experimental investigation of the conditions for which the asymptotic description of longitudinal dispersion given by Taylor (1954) would apply. At non-dimensional times following the release of a dye pulse that are significantly larger than those previously investigated, the integrated concentration curves were observed to be skewed. At relatively short times from release the concentration curves appear to be well described by the models presented by Sullivan (1971) and by Chatwin (1973). Some features of the asymptotic behaviour, namely the translation of the modal value of the integrated concentration curve at the discharge velocity and the constant temporal growth rate of the variance, are observed at the longest times following release. On the basis of these observations it is estimated that a non-dimensional time interval oftu*/d=O(105/R*), whereR*=u*d/v,u*is the friction velocity,vthe kinematic viscosity anddthe tube diameter, is required for the Taylor result to become applicable. Thus application of Taylor's theory is significantly restricted in turbulent flows, especially those with irregular boundaries and those that are not stationary. There the variations in the flow must be small with respect to an equivalent ‘development time’ if a value of the ‘local’ longitudinal diffusion coefficient is to have meaning.

IONIZATION ENERGY AND IMPURITY BAND CONDUCTION OF SHALLOW DONORS IN n-GALLIUM ARSENIDE

1967 ◽  
Vol 45 (1) ◽  
pp. 119-126 ◽  
Author(s):  
J. Basinski ◽  
R. Olivier
Keyword(s):  
Ionization Energy ◽  
Impurity Band ◽  
Shallow Donor ◽  
Band Model ◽  
A Value ◽  
Transition Concentration ◽  
Temperature Electron ◽  
Two Band Model ◽  
Band Conduction ◽  
Made In

Hall effect and resistivity measurements have been made in the temperature range 4.2–360 °K on several samples of n-type GaAs grown under oxygen atmosphere and without any other intentional dopings. The principal shallow donor in this material is considered to be Si. All samples exhibited impurity-band conduction at low temperature. Electron concentrations in the conduction band were calculated, using a two-band model, and then fitted to the usual equation expressing charge neutrality. A value of 2.3 × 10−3 eV was obtained for the ionization energy of the donors, for donor concentration ranging from 5 × 1015 cm−3 to 2 × 1016 cm−3. The conduction in the impurity band was of the hopping type for these concentrations. A value of 3.5 × 1016 cm−3 was obtained for the critical transition concentration of the impurity-band conduction to the metallic type.

Induced polarization and pore radius — A discussion

Geophysics ◽  
2016 ◽  
Vol 81 (5) ◽  
pp. D519-D526 ◽  
Author(s):  
Andreas Weller ◽  
Zeyu Zhang ◽  
Lee Slater ◽  
Sabine Kruschwitz ◽  
Matthias Halisch
Keyword(s):  
Diffusion Coefficient ◽  
Relaxation Time ◽  
Diffusion Coefficients ◽  
Pore Radius ◽  
Mercury Porosimetry ◽  
Induced Polarization ◽  
Reliable Estimate ◽  
Characteristic Relaxation Time ◽  
A Value ◽  
Apparent Diffusion

Permeability estimation from induced polarization (IP) measurements is based on a fundamental premise that the characteristic relaxation time [Formula: see text] is related to the effective hydraulic radius [Formula: see text] controlling fluid flow. The approach requires a reliable estimate of the diffusion coefficient of the ions in the electrical double layer. Others have assumed a value for the diffusion coefficient, or postulated different values for clay versus clay-free rocks. We have examined the link between a widely used single estimate of [Formula: see text] and [Formula: see text] for an extensive database of sandstone samples, in which mercury porosimetry data confirm that [Formula: see text] is reliably determined from a modification of the Hagen-Poiseuille equation assuming that the electrical tortuosity is equal to the hydraulic tortuosity. Our database does not support the existence of one or two distinct representative diffusion coefficients but instead demonstrates strong evidence for six orders of magnitude of variation in an apparent diffusion coefficient that is well-correlated with [Formula: see text] and the specific surface area per unit pore volume [Formula: see text]. Two scenarios can explain our findings: (1) the length scale defined by [Formula: see text] is not equal to [Formula: see text] and is likely much longer due to the control of pore-surface roughness or (2) the range of diffusion coefficients is large and likely determined by the relative proportions of the different minerals (e.g., silica and clays) making up the rock. In either case, the estimation of [Formula: see text] (and hence permeability) is inherently uncertain from a single characteristic IP relaxation time as considered in this study.

scholarly journals Analytical and Experimental Analysis of a Free Link in Contact with a Granular Medium

2013 ◽  
Vol 2013 ◽  
pp. 1-9 ◽  
Author(s):  
Dan B. Marghitu ◽  
Seung Lee
Keyword(s):  
Granular Medium ◽  
Stopping Time ◽  
The Body ◽  
Resistance Force ◽  
Time Interval ◽  
The Moment ◽  
Static Resistance ◽  
The Impact ◽  
Resistance Forces ◽  
Empirical Approaches

In this study, the experimental and the simulation results for a planar free link impacting a granular medium are analyzed. The resistance force of the granular medium on the body from the moment of the impact until the body stops is very important. Horizontal and vertical static resistance forces developed by theoretical and empirical approaches are considered. The penetrating depth of the impacting end of the free link increases with the increase of the initial impacting velocity. We define the stopping time as the time interval from the moment of impact until the vertical velocity of the link end is zero. The stopping time of the end decreases as the initial velocity increases. The faster the end of the link impacts the surface of the granular medium, the sooner it will come to a stop. This phenomenon involves how rapidly a free link strikes the granular medium and how it slows down upon contact.

scholarly journals Ineffable Cultures or Material Devices: What Valuation Studies can Learn from the Disappearance of Ensured Solidarity in a Health Care Market

2015 ◽  
Vol 3 (1) ◽  
pp. 45-73 ◽  
Author(s):  
Teun Zuiderent-Jerak ◽  
Stans Van Egmond
Keyword(s):  
Health Care ◽  
Decisive Role ◽  
Cultural Value ◽  
Health Care Market ◽  
A Value ◽  
Dutch Health ◽  
Short Time ◽  
Regulated Competition ◽  
Made In

Valuation studies addresses how values are made in valuation practices. A next - or rather previous - question becomes: what then makes valuation practices? Two oppositional replies are starting to dominate how that question can be answered: a more materially oriented focus on devices of valuation and a more sociologically inclined focus on ineffable valuation cultures. The debate between proponents of both approaches may easily turn into the kind of leapfrog debates that have dominated many previous discussions on whether culture or materiality would play a decisive role in driving history. This paper explores a less repetitive reply. It does so by analyzing the puzzling case of the demise of solidarity as a core value within the recent Dutch health care system of regulated competition. While “solidarity among the insured” was both a strong cultural value within the Dutch welfare-based health system, and a value that was built into market devices by health economists, within a fairly short time “fairness” became of lesser importance than “competition”. This makes us call for a more historical, relational, and dynamic understanding of the role of economists, market devices, and of culture in valuation studies.

scholarly journals Reaction to a Visual Stimulus: Anticipation with Steady and Dynamic Contractions

2019 ◽  
Vol 69 (1) ◽  
pp. 17-27
Author(s):  
Agostina Casamento-Moran ◽  
Stefan Delmas ◽  
Seoung Hoon Park ◽  
Basma Yacoubi ◽  
Evangelos A. Christou
Keyword(s):  
Reaction Time ◽  
Planning Process ◽  
Dynamic Condition ◽  
Motor Planning ◽  
Reaction Time Task ◽  
Emg Activity ◽  
Time Interval ◽  
Variable Direction ◽  
The Moment ◽  
Study Participants

Abstract Reacting fast to visual stimuli is important for many activities of daily living and sports. It remains unknown whether the strategy used during the anticipatory period influences the speed of the reaction. The purpose of this study was to determine if reaction time (RT) differs following a steady and a dynamic anticipatory strategy. Twenty‐two young adults (21.0 ± 2.2 yrs, 13 women) participated in this study. Participants performed 15 trials of a reaction time task with ankle dorsiflexion using a steady (steady force at 15% MVC) and a dynamic (oscillating force from 10‐20% MVC) anticipatory strategy. We recorded primary agonist muscle (tibialis anterior; TA) electromyographic (EMG) activity. We quantified RT as the time interval from the onset of the stimulus to the onset of force. We found that a dynamic anticipatory strategy, compared to the steady anticipatory strategy, resulted in a longer RT (p = 0.04). We classified trials of the dynamic condition based on the level and direction of anticipatory force at the moment of the response. We found that RT was longer during the middle descending relative to the middle ascending and the steady conditions (p < 0.01). All together, these results suggest that RT is longer when preceded by a dynamic anticipatory strategy. Specifically, the longer RT is a consequence of the variable direction of force at which the response can occur, which challenges the motor planning process.

scholarly journals Notas em torno do cinema militante de 1960 e 1970 / Notes on the Militant Cinema of the Sixties and Seventies

2019 ◽  
Vol 15 (1) ◽  
pp. 79
Author(s):  
Julia Fagioli
Keyword(s):  
Point Of View ◽  
The Sixties ◽  
Political Challenge ◽  
The Moment ◽  
Collective Production ◽  
Made In

Resumo: Neste trabalho buscamos realizar uma breve genealogia – sempre inacabada – acerca das formas como a política – especificamente sua dimensão militante e engajada – se manifesta no cinema, a partir de um recorte histórico que privilegia a produção militante e coletiva dos anos 1960 e 1970. Nesse período vários coletivos e iniciativas individuais surgiram em torno de um cinema engajado. Ao recuperar algumas dessas iniciativas, é possível retomar também as questões que elas abordavam, tais como o ato de delegar a câmera ao trabalhador, as relações entre as imagens filmadas num momento de urgência – o ponto de vista – e sua articulação na montagem, o modo de distribuição dos filmes militantes. Assim, percebemos o quanto esse momento de contestação política será também o de uma invenção formal no âmbito do cinema.Palavras-chave: cinema militante; cinema coletivo; contra-informação.Abstract: In this paper we seek to develop a genealogy – always unfinished – about the ways in which politics – specifically in its militant and engaged dimensions – manifests itself in cinema, throughout a historical frame that privileges the militant and collective production from the sixties and the seventies. During this period, several collectives and individual initiatives emerged regarding an engaged cinema. By recovering some of these initiatives it is possible to also recapture the issues that they addressed, such as the act of delegating the camera to the workers, the relations between the images made in moments of urgency – the point of view – and its assemblage in montage, the modes of distribution of the militant films. Therefore, we realize that the moment of political challenge will also be of formal invention in the scope of cinema.Keywords: militant cinema; collective cinema; counter-information.

A nuclear magnetic resonance investigation of three solid benzenes

1953 ◽  
Vol 218 (1135) ◽  
pp. 537-552 ◽  
Keyword(s):  
Crystal Structure ◽  
Nuclear Magnetic Resonance ◽  
Relaxation Time ◽  
Lattice Relaxation ◽  
Lattice Relaxation Time ◽  
Spin Lattice Relaxation ◽  
Second Moment ◽  
Spin Lattice ◽  
Second Moments ◽  
A Value

The nuclear magnetic resonance absorption spectrum and the spin-lattice relaxation time have been measured for the protons in three isotopic species of benzene in polycrystalline form between 75 and 278° K. The three species were C 6 H 6 , C 6 H 5 D and 1. 3. 5 - C 6 H 3 D 3 . For all three species the measured spectrum has its full rigid lattice width below 90° K. A method of analysis is developed which makes it possible to derive separately the intramolecular and the intermolecular contributions to the second moment (mean square width) of the spectrum from the measured second moments, without the necessity of knowing the crystal structure. From the intramolecular contribution it is found that the separation of neighbouring protons in the C 6 H 6 molecule is 2.495 ± 0.018 Å. The intermolecular contribution is in agreement with a value calculated from a knowledge of the crystal structure. On warming from 90 to 120°K the spectrum for all three species narrows considerably. From 120°K to the melting-point (278.7° K) the second moments remain almost constant. The second moment separation procedure is also applied in this range and leads to the conclusion that the narrowing is caused by reorientation of the molecules about their hexad axes in the crystal lattice. Analysis of the measurements of the spin-lattice relaxation time shows that for all three species the reorientation process is governed by an activation energy of 3.7 ± 0.2 kcal/mole. The reorientation frequency is of the order of 10 4 c/s at 85° K and rises to a value of the order of 10 11 c/s just below the melting-point. The relationship between the present experimental results and recent measurements of the Raman spectrum of solid benzene is discussed. Finally, consideration is given to the application to other materials of methods of separating the intra- and intermolecular contributions to the second moment.

A technology review of recycling methods for fiber-reinforced thermosets

2021 ◽  
pp. 073168442110552
Author(s):  
Xiao Xue ◽  
Shu-Yan Liu ◽  
Zhao-Yang Zhang ◽  
Qing-Zhou Wang ◽  
Cheng-Zhi Xiao
Keyword(s):  
End Of Life ◽  
Complex Structure ◽  
Waste Recycling ◽  
Fiber Reinforced ◽  
Reinforced Plastics ◽  
Thermal Pyrolysis ◽  
Challenges And Opportunities ◽  
Fiber Reinforced Plastics ◽  
Technology Review ◽  
Made In

The rapidly rising demand for fiber-reinforced plastics (FRPs) has led to large volumes of manufacturing and end-of-life waste. Recycling fiber-reinforced thermosets is very difficult owing to their complex structure and heterogeneity. Landfill and incineration have become the most commonly used methods for eliminating non-degradable FRP waste, which adversely affects the environment and ecology. The purpose of this review is to evaluate end-of-life FRP recycling technologies in terms of optimizing the reuse/recycling of resources and eliminating waste, thereby improving FRP waste management. The technical progress made in the recycling of thermosetting composites is reviewed, including mechanical, thermal (pyrolysis and fluidized-bed), and chemical (critical fluid and low-temperature solvent) methods. The technical feasibility of each method was compared, and the economic and environmental impacts were considered. The challenges and opportunities facing the establishment of a composite recycling market in the future are examined. Finally, we provide a comprehensive summary of the scope of each recycling method.

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