scholarly journals Local direction change of surface gliding microtubules

2019 ◽  
Vol 116 (5) ◽  
pp. 1128-1138 ◽  
Author(s):  
Feiran Li ◽  
Jing Pan ◽  
Jong Hyun Choi
Keyword(s):  
Direction Change ◽  
Local Direction

scholarly journals Directional selectivity and its use in early visual processing

1981 ◽  
Vol 211 (1183) ◽  
pp. 151-180 ◽  
Keyword(s):  
Visual Processing ◽  
Visual Motion ◽  
Time Derivative ◽  
Receptive Fields ◽  
Specific Model ◽  
Zero Crossings ◽  
Second Stage ◽  
Early Visual Processing ◽  
Local Direction ◽  
Zero Values

The construction of directionally selective units, and their use in the processing of visual motion, are considered. The zero crossings of ∇ 2 G(x, y) ∗ I(x, y) are located, as in Marr & Hildreth (1980). That is, the image is filtered through centre-surround receptive fields, and the zero values in the output are found. In addition, the time derivative ∂[∇ 2 G(x, y) ∗ l(x, y) ]/∂ t is measured at the zero crossings, and serves to constrain the local direction of motion to within 180°. The direction of motion can be determined in a second stage, for example by combining the local constraints. The second part of the paper suggests a specific model of the information processing by the X and Y cells of the retina and lateral geniculate nucleus, and certain classes of cortical simple cells. A number of psychophysical and neurophysiological predictions are derived from the theory.

Consistency of Individual Patterns of Autokinetic Direction

1966 ◽  
Vol 23 (3_suppl) ◽  
pp. 1119-1123 ◽  
Author(s):  
Douglas G. Pearce
Keyword(s):  
Directional Dominance ◽  
Direction Change ◽  
Coefficient Of Concordance ◽  
The Individual ◽  
Range Of Values

Four Ss continuously reported the direction of autokinetic movement during 20 10-min. sessions. Individual patterns of directional dominance and change in direction over the 20 sessions were assessed by means of the Kendall coefficient of concordance. Individual patterns of directional dominance were consistent; the range of values of W for the four Ss was from 0.619 to 0.791. The individual patterns of direction change were generally less consistent; the range of W was from 0.242 to 0.704.

scholarly journals A Video Based Fire Smoke Detection Using Robust AdaBoost

Sensors ◽  
2018 ◽  
Vol 18 (11) ◽  
pp. 3780 ◽  
Author(s):  
Xuehui Wu ◽  
Xiaobo Lu ◽  
Henry Leung
Keyword(s):  
Smoke Detector ◽  
Dynamic Features ◽  
Smoke Detection ◽  
Motion Direction ◽  
Direction Change ◽  
Satisfactory Performance ◽  
Orientation Histogram ◽  
Fire Smoke ◽  
Motion Speed ◽  
Camera Sensors

This work considers using camera sensors to detect fire smoke. Static features including texture, wavelet, color, edge orientation histogram, irregularity, and dynamic features including motion direction, change of motion direction and motion speed, are extracted from fire smoke to train and test with different combinations. A robust AdaBoost (RAB) classifier is proposed to improve training and classification accuracy. Extensive experiments on well known challenging datasets and application for fire smoke detection demonstrate that the proposed fire smoke detector leads to a satisfactory performance.

Study on the Bubble Dynamics and the Exciting Force in a Bended Pipe Based on BEM

2016 ◽  
Author(s):  
Y. L. Liu ◽  
Z. L. Tian
Keyword(s):  
Numerical Model ◽  
Potential Theory ◽  
Bubble Dynamics ◽  
Flow Speed ◽  
Exciting Force ◽  
Incoming Flow ◽  
Bubble Motion ◽  
Dynamics Model ◽  
Pipe Surface ◽  
Direction Change

Nonlinear bubble dynamics in a pipeline and its exciting force are investigated by a numerical model based on BEM. The bubble motion is one of the main causes that the pipeline vibrates and generates noise in modern ships. The numerical bubble dynamics model is established under the incompressible potential theory. Bubble motion with different incoming flow in a bended pipe is simulated. We found that the bubble develops jet when it passes by the bend, and adjoin to the pipe surface in the side of the fillet center. The pulsation and the direction change of the bubble apply an exciting force on the pipe which has a positive correlation with the incoming flow speed and may lead vibration and noise.

scholarly journals Detection and characterization of extreme wind speed ramps

2019 ◽  
Vol 4 (3) ◽  
pp. 385-396 ◽  
Author(s):  
Ásta Hannesdóttir ◽  
Mark Kelly
Keyword(s):  
Wind Speed ◽  
Rise Time ◽  
Error Function ◽  
General Pattern ◽  
Analytical Form ◽  
Direction Change ◽  
Extreme Wind Speed ◽  
Time Variables ◽  
The One ◽  
Speed Fluctuations

Abstract. The present study introduces a new method to characterize ramp-like wind speed fluctuations, including coherent gusts. This method combines two well-known methods: the continuous wavelet transform and the fitting of an analytical form based on the error function. The method provides estimation of ramp amplitude and rise time, and is herein used to statistically characterize ramp-like fluctuations at three different measurement sites. Together with the corresponding amplitude of wind direction change, the ramp amplitude and rise time variables are compared to the extreme coherent gust with direction change from the IEC wind turbine safety standard. From the comparison we find that the observed amplitudes of the estimated fluctuations do not exceed the one prescribed in the standard, but the rise time is generally much longer, on average around 200 s. The direction change does however exceed the one prescribed in the standard several times, but for those events the rise time is a minute or more. We also demonstrate a general pattern in the statistical behaviour of the characteristic ramp variables, noting their wind speed dependence, or lack thereof, at the different sites.

scholarly journals Features of the Earth surface deformations in the Kamchatka peninsula and their relation to geoacoustic emission

Solid Earth ◽  
2014 ◽  
Vol 5 (2) ◽  
pp. 1293-1300 ◽  
Author(s):  
I. A. Larionov ◽  
Y. V. Marapulets ◽  
B. M. Shevtsov
Keyword(s):  
Michelson Interferometer ◽  
Kamchatka Peninsula ◽  
Frequency Range ◽  
Near Surface ◽  
Geoacoustic Emission ◽  
Direction Change ◽  
The Earth ◽  
Deformation Processes ◽  
Rock Deformations ◽  
Artificial Water

Abstract. The paper presents the results of investigations of deformation processes in the near-surface sedimentary rocks, which have been carried out in a seismically active region of the Kamchatka peninsula since 2007. The peculiarity of the experiments on registration of geodeformations is the application of a laser strainmeter–interferometer constructed according to the Michelson interferometer scheme. Besides rock deformations, geoacoustic emission in the frequency range from several hertz to the first tens of kilohertz is under investigation. Piezoceramic hydrophones installed in artificial water reservoirs are applied. It is shown that periods of primary rock compression and tension with a duration of up to several months are distinguished in the geodeformation process at the observation site. During the direction change in the deformations, when the geodeformation process rate grows, an increase in geoacoustic radiation is observed.

Inferred seismic fault associated with the 1998 M = 6.2 Zhangbei-Shanyi earthquake, Hebei Province, China

1999 ◽  
Vol 89 (2) ◽  
pp. 550-554 ◽  
Author(s):  
Aiming Lin ◽  
Guochun Zhao ◽  
Guozhe Zhao ◽  
Xiwei Xu
Keyword(s):  
Seismic Data ◽  
Active Fault ◽  
Lateral Displacement ◽  
Displacement Component ◽  
The North ◽  
Seismic Fault ◽  
Direction Change ◽  
Western Side ◽  
Northwest Region ◽  
Beijing China

Abstract The shallow, Ms = 6.2, 1998 Zhangbei-Shanyi earthquake that affected the northwest region of Beijing, China, occurred at the intersection of two active fault zones, located on the north and east edges of the Ordos tableland. A detailed map of the intensity distribution of damaged building shows that the most damaged area was centered 8 to 10 km away from the epicenter, including an ellipsoidal region with a strike of NNE, where more than 70 to 90% of buildings were destroyed. Many chimneys and gate pillars were broken and fell toward the SSE-SSW direction in the western side of the most damaged area and to the NNE-NNW direction in the eastern side. Aftershocks were also concentrated in the most damaged area. It is inferred that the boundary of the downfallen direction change is the surface trace of the seismic fault. Based on the seismic data, the distribution of damaged buildings, and the downfallen directions of 70 chimneys and gate pillars, it is identified that the seismic fault is a thrust fault striking NNE and dipping 40° to 50° northwest with a large right-lateral displacement component.

Abstract 3491: Endo-Epicardial Dissociation of Electrical Activity Increases During the Development of the Substrate for Atrial Fibrillation in the Goat

Circulation ◽  
2008 ◽  
Vol 118 (suppl_18) ◽  
Author(s):  
Jens Eckstein ◽  
Bart Maesen ◽  
Sander Verheule ◽  
Maurits Allessie ◽  
Ulrich Schotten
Keyword(s):  
Atrial Fibrillation ◽  
Mapping Tool ◽  
Time Criterion ◽  
High Incidence ◽  
Subepicardial Layer ◽  
Local Direction ◽  
Endocardial Layer ◽  
Activation Times ◽  
Over Time

Background: The high incidence of transmural conduction of fibrillation waves (breakthroughs) in a complex substrate for atrial fibrillation (AF) implies the presence of electrical dissociation between the subepicardial layer (Epi) and the endocardial bundle network (Endo). The presence of this Endo/Epi dissociation (EED) in remodeled atria and its role in the progressive stabilization of AF over time has not been studied yet. Methods: We developed a mapping tool for synchronous Endo/Epi mapping (spatial resolution 1.6mm) with 90 exactly opposing electrode pairs (open chest experiment). We included 3 groups of goats: C = Control (acute AF induced by 50Hz burst pacing, n=7), 3wk = 3weeks AF (n=7) and 6mo = 6months AF (n=7). Dissociated activity was postulated when either activation times differed by more than 12ms vertically or 8ms horizontally (indicating a local conduction velocity < 20cm/s) or local direction of propagation between Endo and Epi differed by more than 90 degrees. To monitor AF stability, repetitive in-vivo cardioversion experiments with class 1C drugs were performed in 6 of the 6mo goats at 2,6,10 and 14wk AF. Results: Applying the time criterion, EED increased from 15±4% (C) to 22±11% (3wk) and 35±13% (6mo, p=0.002 vs. C). Also the differences in the direction of propagation significantly contributed to EED. Using the combined criterion, EED increased from 38±5% (C) to 46±10% (3wk) and 53±11% (6mo, p=0.007 vs. C). Dissociation within the epicardial and the endocardial layer (time criterion) increased to a comparable extent (19±8% vs. 27±14% vs. 37± 7%, p<0.001 C vs. 6mo). Mean Endo/Epi activation time differences were close to 0ms in all three groups (−1.0±15ms vs. −0.8±16ms vs. −0.3±20ms), ruling out preferential conduction from Endo to Epi or vice versa. Success rate of cardioversion experiments decreased from 83% (2w) to 33% (6wk) to 16% (10wk) to 0% (14wk) indicating increasing stability of AF over time. Conclusion: During AF, pronounced EED occurs. EED (like dissociation within Endo and Epi) increases over time, contributing to the progressive stabilization of AF. Enhanced EED might explain the high incidence of transmural conduction (breakthroughs) in a complex substrate for AF.

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