Noninvasive fiber optic measurement of carotid to radial apparent phase velocity in hypertensive subjects

2002 ◽  
Author(s):  
J.K.-J. Li ◽  
D. Amory ◽  
M. Singh ◽  
R. McMahon ◽  
Ying Zhu ◽  
...  
Keyword(s):  
Phase Velocity ◽  
Fiber Optic

Phase velocity measurements in bubbly liquids using a fiber optic laser interferometer

1995 ◽  
Vol 97 (3) ◽  
pp. 1621-1624 ◽  
Author(s):  
Stanley A. Cheyne ◽  
Carl T. Stebbings ◽  
Ronald A. Roy
Keyword(s):  
Phase Velocity ◽  
Laser Interferometer ◽  
Fiber Optic ◽  
Velocity Measurements ◽  
Bubbly Liquids

scholarly journals Acoustic phase velocity measurements in a bubbly liquid using a fiber optic laser Doppler velocimeter

1992 ◽  
Vol 92 (4) ◽  
pp. 2454-2454
Author(s):  
Stanley A. Cheyne ◽  
Carl T. Stebbings ◽  
Ronald A. Roy
Keyword(s):  
Phase Velocity ◽  
Fiber Optic ◽  
Laser Doppler ◽  
Laser Doppler Velocimeter ◽  
Bubbly Liquid ◽  
Velocity Measurements ◽  
Acoustic Phase

On the transmission of data packets through fiber-optic cables of uniform index

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Sujit K. Bose
Keyword(s):  
Phase Velocity ◽  
Maxwell Equations ◽  
Fiber Optic ◽  
Experimental Measurements ◽  
Property A ◽  
Wave Groups ◽  
Data Packets ◽  
Tail Distribution ◽  
Poisson Arrivals ◽  
Frequency Phase

Abstract The treatment of Maxwell equations show that propagating wave of packets in fiber-optic cables is dispersive, propagating in groups, such that group velocity along certain curves in the frequency-phase velocity diagrams vanishes. It is suggested that stalling of wave groups is responsible, for bursting propagation observed in experimental measurements, causing some delay in transmission. The dispersion equations developed here, are different from those given in texts that are based on “weakly guiding approximation”. The queue of such data packets arriving at a router station is found to have a “raised tail” distribution unlike that of Poisson arrivals. For accounting the property, a Mittag–Leffler function distribution (MLFD) of probability is used following a modification of that for a Poisson process, the tail raising is shown to cause delay in transmission, and its estimate is analysed based on the theory.

Imaging and diffraction modes in Scanning Transmission Electron Microscopy

1986 ◽  
Vol 44 ◽  
pp. 684-687
Author(s):  
J. M. Cowley ◽  
R. Glaisher ◽  
J. A. Lin ◽  
H.-J. Ou
Keyword(s):  
Scanning Transmission Electron Microscopy ◽  
High Efficiency ◽  
Fiber Optic ◽  
Image Intensifier ◽  
Detector System ◽  
Detector Plane ◽  
Secondary Electrons ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Special Detector

Some of the most important applications of STEM depend on the variety of imaging and diffraction made possible by the versatility of the detector system and the serial nature, of the image acquisition. A special detector system, previously described, has been added to our STEM instrument to allow us to take full advantage of this versatility. In this, the diffraction pattern in the detector plane may be formed on either of two phosphor screens, one with P47 (very fast) phosphor and the other with P20 (high efficiency) phosphor. The light from the phosphor is conveyed through a fiber-optic rod to an image intensifier and TV system and may be photographed, recorded on videotape, or stored digitally on a frame store. The P47 screen has a hole through it to allow electrons to enter a Gatan EELS spectrometer. Recently a modified SEM detector has been added so that high resolution (10Å) imaging with secondary electrons may be used in conjunction with other modes.

Vestibular Function and Motion Sickness Susceptibility: Videonystagmographic Evidence From Oculomotor and Caloric Tests

2020 ◽  
Vol 29 (2) ◽  
pp. 188-198
Author(s):  
Cynthia G. Fowler ◽  
Margaret Dallapiazza ◽  
Kathleen Talbot Hadsell
Keyword(s):  
Phase Velocity ◽  
Motion Sickness ◽  
Repeated Measures ◽  
Short Form ◽  
Vestibular Function ◽  
Slow Phase ◽  
Test Results ◽  
Normal Range ◽  
Slow Phase Velocity ◽  
Caloric Tests

Purpose Motion sickness (MS) is a common condition that affects millions of individuals. Although the condition is common and can be debilitating, little research has focused on the vestibular function associated with susceptibility to MS. One causal theory of MS is an asymmetry of vestibular function within or between ears. The purposes of this study, therefore, were (a) to determine if the vestibular system (oculomotor and caloric tests) in videonystagmography (VNG) is associated with susceptibility to MS and (b) to determine if these tests support the theory of an asymmetry between ears associated with MS susceptibility. Method VNG was used to measure oculomotor and caloric responses. Fifty young adults were recruited; 50 completed the oculomotor tests, and 31 completed the four caloric irrigations. MS susceptibility was evaluated with the Motion Sickness Susceptibility Questionnaire–Short Form; in this study, percent susceptibility ranged from 0% to 100% in the participants. Participants were divided into three susceptibility groups (Low, Mid, and High). Repeated-measures analyses of variance and pairwise comparisons determined significance among the groups on the VNG test results. Results Oculomotor test results revealed no significant differences among the MS susceptibility groups. Caloric stimuli elicited responses that were correlated positively with susceptibility to MS. Slow-phase velocity was slowest in the Low MS group compared to the Mid and High groups. There was no significant asymmetry between ears in any of the groups. Conclusions MS susceptibility was significantly and positively correlated with caloric slow-phase velocity. Although asymmetries between ears are purported to be associated with MS, asymmetries were not evident. Susceptibility to MS may contribute to interindividual variability of caloric responses within the normal range.

Synthesis, performance and growth mechanism of silver nanoparticle coated SERS fiber probe

2019 ◽  
Vol 107 (3) ◽  
pp. 305
Author(s):  
Mengmei Geng ◽  
Yuting Long ◽  
Tongqing Liu ◽  
Zijuan Du ◽  
Hong Li ◽  
...  
Keyword(s):  
Silver Nanoparticles ◽  
Absorption Spectrum ◽  
Reaction Time ◽  
Growth Mechanism ◽  
Fiber Optic ◽  
Fiber Optic Probe ◽  
Visible Absorption ◽  
Fiber Probe ◽  
Surface Enhanced Raman ◽  
Optic Probe

Surface-enhanced Raman Scattering (SERS) fiber probe provides abundant interaction area between light and materials, permits detection within limited space and is especially useful for remote or in situ detection. A silver decorated SERS fiber optic probe was prepared by hydrothermal method. This method manages to accomplish the growth of silver nanoparticles and its adherence on fiber optic tip within one step, simplifying the synthetic procedure. The effects of reaction time on phase composition, surface plasmon resonance property and morphology were investigated by X-ray diffraction analysis (XRD), ultraviolet-visible absorption spectrum (UV-VIS absorption spectrum) and scanning electron microscope (SEM). The results showed that when reaction time is prolonged from 4–8 hours at 180 °C, crystals size and size distribution of silver nanoparticles increase. Furthermore, the morphology, crystal size and distribution density of silver nanoparticles evolve along with reaction time. A growth mechanism based on two factors, equilibrium between nucleation and growth, and the existence of PVP, is hypothesized. The SERS fiber probe can detect rhodamin 6G (R6G) at the concentration of 10−6 M. This SERS fiber probe exhibits promising potential in organic dye and pesticide residue detection.

Increasing the information capacity of a fiber-optic multi-sensor converter of binary mechanical signals into electrical signals

2020 ◽  
pp. 15-23
Author(s):  
V. M. Grechishnikov ◽  
E. G. Komarov
Keyword(s):  
Fiber Optic ◽  
Information Capacity ◽  
Parallel Structure ◽  
Optical Scheme ◽  
Digital To Analog Converter ◽  
Electrical Signals ◽  
Mechanical Signals ◽  
Analog Converter ◽  
Output Code ◽  
Digital To Analog

The design and operation principle of a multi-sensor Converter of binary mechanical signals into electrical signals based on a partitioned fiber-optic digital-to-analog Converter with a parallel structure is considered. The digital-to-analog Converter is made from a set of simple and technological (three to five digit) fiber-optic digital-to-analog sections. The advantages of the optical scheme of the proposed. Converter in terms of metrological and energy characteristics in comparison with single multi-bit converters are justified. It is shown that by increasing the number of digital-analog sections, it is possible to repeatedly increase the information capacity of a multi-sensor Converter without tightening the requirements for its manufacturing technology and element base. A mathematical model of the proposed Converter is developed that reflects the features of its operation in the mode of sequential time conversion of the input code vectors of individual fiber-optic sections into electrical analogues and the formation of the resulting output code vector.

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