scholarly journals Functional optoretinography: concurrent OCT monitoring of intrinsic signal amplitude and phase dynamics in human photoreceptors

2021 ◽  
Author(s):  
Guangying Ma ◽  
Taeyoon Son ◽  
Tae-Hoon Kim ◽  
Xincheng Yao
Keyword(s):  
Signal Amplitude ◽  
Phase Dynamics ◽  
Intrinsic Signal

The Effects of Variable-Interval and Fixed-Interval Signal Presentation Schedules on the Auditory Evoked Response

1969 ◽  
Vol 12 (1) ◽  
pp. 199-209 ◽  
Author(s):  
David A. Nelson ◽  
Frank M. Lassman ◽  
Richard L. Hoel
Keyword(s):  
Variable Interval ◽  
Tone Burst ◽  
Signal Amplitude ◽  
Fixed Interval ◽  
Interval Schedule ◽  
Sensation Level ◽  
Fixed Interval Schedule ◽  
Auditory Evoked Responses ◽  
Auditory Evoked Response ◽  
Signal Presentation

Averaged auditory evoked responses to 1000-Hz 20-msec tone bursts were obtained from normal-hearing adults under two different intersignal interval schedules: (1) a fixed-interval schedule with 2-sec intersignal intervals, and (2) a variable-interval schedule of intersignal intervals ranging randomly from 1.0 sec to 4.5 sec with a mean of 2 sec. Peak-to-peak amplitudes (N 1 — P 2 ) as well as latencies of components P 1 , N 1 , P 2 , and N 2 were compared under the two different conditions of intersignal interval. No consistent or significant differences between variable- and fixed-interval schedules were found in the averaged responses to signals of either 20 dB SL or 50 dB SL. Neither were there significant schedule differences when 35 or 70 epochs were averaged per response. There were, however, significant effects due to signal amplitude and to the number of epochs averaged per response. Response amplitude increased and response latency decreased with sensation level of the tone burst.

Electrical Capacitance Volume Tomography (ECVT) for industrial and medical applications-An Overview

2015 ◽  
Vol 11 (1) ◽  
pp. 2897-2908
Author(s):  
Mohammed S.Aljohani
Keyword(s):  
Imaging Technique ◽  
Three Dimensional ◽  
Biological Processes ◽  
Electrical Capacitance ◽  
Image Reconstruction Techniques ◽  
Phase Dynamics ◽  
Non Invasive ◽  
Electrical Capacitance Volume Tomography ◽  
And Performance ◽  
Optimization And Performance

Tomography is a non-invasive, non-intrusive imaging technique allowing the visualization of phase dynamics in industrial and biological processes. This article reviews progress in Electrical Capacitance Volume Tomography (ECVT). ECVT is a direct 3D visualizing technique, unlike three-dimensional imaging, which is based on stacking 2D images to obtain an interpolated 3D image. ECVT has recently matured for real time, non-invasive 3-D monitoring of processes involving materials with strong contrast in dielectric permittivity. In this article, ECVT sensor design, optimization and performance of various sensors seen in literature are summarized. Qualitative Analysis of ECVT image reconstruction techniques has also been presented.

Stereospecific 1,3-H Transfer of Indenols Proceeds via Persistent Ion-Pairs Anchored By NH···Pi Interactions

2018 ◽  
Author(s):  
David Ascough ◽  
Fernanda Duarte ◽  
Robert Paton
Keyword(s):  
Computational Analysis ◽  
Ion Pairs ◽  
Ion Pair ◽  
Hydrogen Atom Transfer ◽  
Polar Solvents ◽  
Chirality Transfer ◽  
Activation Barriers ◽  
Sense And Avoid ◽  
Phase Dynamics ◽  
Pi Interactions

The base-catalyzed rearrangement of arylindenols is a rare example of a suprafacial [1,3]-hydrogen atom transfer. The mechanism has been proposed to proceed via sequential [1,5]-sigmatropic shifts, which occur in a selective sense and avoid an achiral intermediate. A computational analysis using quantum chemistry casts serious doubt on these suggestions: these pathways have enormous activation barriers and in constrast to what is observed experimentally, they overwhelmingly favor a racemic product. Instead we propose that a suprafacial [1,3]-prototopic shift occurs in a two-step deprotonation/reprotonation sequence. This mechanism is favored by 15 kcal mol<sup>-1</sup> over that previously proposed. Most importantly, this is also consistent with stereospecificity since reprotonation occurs rapidly on the same p-face. We have used explicitly-solvated molecular dynamics studies to study the persistence and condensed-phase dynamics of the intermediate ion-pair formed in this reaction. Chirality transfer is the result of a particularly resilient contact ion-pair, held together by electrostatic attraction and a critical NH···p interaction which ensures that this species has an appreciable lifetime even in polar solvents such as DMSO and MeOH.

Effects of Background Event Rate and Critical Signal Amplitude on Vigilance Performance

1974 ◽  
Vol 38 (3_suppl) ◽  
pp. 1175-1181 ◽  
Author(s):  
Kurt R. Metzger ◽  
Joel S. Warm ◽  
Roderick J. Senter
Keyword(s):  
Event Detection ◽  
Detection Probability ◽  
Event Rate ◽  
Signal Amplitude ◽  
Overt Response ◽  
Vigilance Performance ◽  
Background Event ◽  
Critical Signal

Ss monitored a display consisting of the repetitive presentation of pairs of movements of a bar of light. A neutral background event, for which no overt response was required, was a double deflection of 24 mm. The critical signal for detection was a longer deflection in the second movement within an event. Detection probability was greater for incremental excursions of 33% relative to 8.3% of the base movement. This effect was enhanced twofold when the event rate in which the signals were embedded was 21 as compared to 6 events/min. The results are considered in terms of the elicited observing rate hypothesis proposed by Jerison (1970).

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