scholarly journals Application of genetic algorithm in extracting cell dielectric characteristics with electrorotation

2019 ◽  
Vol 8 (1) ◽  
pp. 34-39 ◽  
Author(s):  
Elnaz Alizadeh-Haghighi ◽  
Samad Jafarmadar ◽  
Shahram Khalilarya
Keyword(s):  
Genetic Algorithm ◽  
Low Frequency ◽  
Peak Frequency ◽  
Optimization Process ◽  
Low Frequencies ◽  
Dielectric Characteristics ◽  
Medium Conductivity

Abstract In this study the transformed theory is applied to derive the dielectric characteristics of cells, considering the electrorotation (ER) peak frequency. In current studies, estimations of low frequency, which are credible for the values less than 1 mS/m for medium conductivity, are used to obtain the corresponding permittivity and conductivity of cells. Unlike the presented works, the transformed theory applies the comprehensive statement for corresponding permittivity and conductivity of cells. In the transformed theory, the membrane and interior characteristics could be obtained from the high and the low frequencies of peak ER, for all values of conductivity of medium. Characteristics of cells are obtained via optimization of an equation for the conductivity of medium regarding the peak ER frequency. The optimization process is performed applying genetic algorithm due to its swift adaptation to the problem and faster convergence.

The origin of the anomalous low-frequency vibrational behaviour of amorphous solids

1992 ◽  
Vol 02 ◽  
pp. C2-279-C2-283
Author(s):  
S. R. ELLIOTT
Keyword(s):  
Low Frequency ◽  
Peak Frequency ◽  
Amorphous Solids ◽  
Boson Peak ◽  
Low Frequencies ◽  
Crystalline Materials ◽  
Medium Range ◽  
Phonon Localization ◽  
Strong Scattering ◽  
Vibrational Density

The anomalous vibrational behaviour exhibited by non-crystalline materials - a peak in the vibrational density of states, and in the Raman spectrum (the boson peak) at low frequencies, and a peak in the heat capacity and a plateau in the thermal conductivity at low temperatures - is ascribed ta phonon localization associated with the strong scattering of phonons by density-fluctuation domains in the structure. Within such domains, short-range and medium-range arder is maintained, and outside them the material is structurally homogeneous and isotropie. This model can also explain the correlation between the boson-peak frequency and the position of the first sharp diffraction peak in the structure factor observed in a number of inorganie and polymerie amorphous solids.

Abstract 4666: Anatomic Substrate as Determinant of Dominant Frequency Dynamics During Human Ventricular Fibrillation

Circulation ◽  
2008 ◽  
Vol 118 (suppl_18) ◽  
Author(s):  
Karthikeyan Umapathy ◽  
Stephane Masse ◽  
Elias Sevaptsidis ◽  
John Asta ◽  
Talha Farid ◽  
...  
Keyword(s):  
Low Frequency ◽  
Electrode Array ◽  
Peak Frequency ◽  
Dominant Frequency ◽  
Physiological Factors ◽  
Low Frequencies ◽  
Bipolar Electrodes ◽  
Df Analysis ◽  
Spatio Temporal ◽  
Spatial Locations

Background: Dominant frequency (DF) analysis is a common way of quantitatively studying the spatio-temporal variation of frequency during VF. Areas of high frequencies (e.g. rotors) and low frequencies (e.g. blocks) have been associated with the occurrence and maintenance of VF. However, the relation of these high or low frequency areas to anatomical or physiological substrate remains unclear. Objective: We tested the hypothesis that the Max-Min DF locations in the epicardium during VF are due to anatomical substrate. Methods and Results: We analyzed 33, 4 seconds VF episodes acquired from 6 isolated human hearts using a Langendorff setup. The hearts were received from the heart-transplanted patients with informed consent. Electrode array consisting 112 bipolar electrodes was used to acquire the surface unipolar and bipolar electrograms from the epicardium. DF was computed as the peak frequency of the VF segment from each of electrodes using Welch’s modified periodogram method. From the DF distribution, the regions of max and min frequencies were identified for LV and RV regions. Scar maps were computed for each of the 6 hearts using a previously published method by mapping the amplitude of bipolar electrograms (<0.5mv = scar) during the pacing protocol. The areas of max-min DF frequencies in each of the VF episode were compared to the corresponding spatial locations in the scar map. Table 1 shows the match between the max-min DF frequency locations and the scar locations. 50% of max-min DF frequencies locations match the scar locations and in 97% of the matched locations the max-min DF occur at the vicinity of the scar. Conclusion: During human VF, DF dynamics are only partially explained by the anatomical substrate. This suggests that ion channel heterogeneity and dynamic physiological factors may play an important role in determining fibrillation dynamics. Match Between Max-Min DF locations and Scar Locations

scholarly journals Earless toads sense low frequencies but miss the high notes

2017 ◽  
Vol 284 (1864) ◽  
pp. 20171670 ◽  
Author(s):  
Molly C. Womack ◽  
Jakob Christensen-Dalsgaard ◽  
Luis A. Coloma ◽  
Juan C. Chaparro ◽  
Kim L. Hoke
Keyword(s):  
High Frequency ◽  
Species Differences ◽  
Low Frequency ◽  
Auditory Brainstem ◽  
Low Frequencies ◽  
Hearing Sensitivity ◽  
Sensory Pathways ◽  
Airborne Sound ◽  
Vibrational Sensitivity ◽  
Species Specific

Sensory losses or reductions are frequently attributed to relaxed selection. However, anuran species have lost tympanic middle ears many times, despite anurans' use of acoustic communication and the benefit of middle ears for hearing airborne sound. Here we determine whether pre-existing alternative sensory pathways enable anurans lacking tympanic middle ears (termed earless anurans) to hear airborne sound as well as eared species or to better sense vibrations in the environment. We used auditory brainstem recordings to compare hearing and vibrational sensitivity among 10 species (six eared, four earless) within the Neotropical true toad family (Bufonidae). We found that species lacking middle ears are less sensitive to high-frequency sounds, however, low-frequency hearing and vibrational sensitivity are equivalent between eared and earless species. Furthermore, extratympanic hearing sensitivity varies among earless species, highlighting potential species differences in extratympanic hearing mechanisms. We argue that ancestral bufonids may have sufficient extratympanic hearing and vibrational sensitivity such that earless lineages tolerated the loss of high frequency hearing sensitivity by adopting species-specific behavioural strategies to detect conspecifics, predators and prey.

scholarly journals 82 Struggle behavior and vocalizations of male piglets during castration

2020 ◽  
Vol 98 (Supplement_3) ◽  
pp. 3-4
Author(s):  
Maria E Lou ◽  
Yuzhi Li ◽  
Beth Ventura
Keyword(s):  
Birth Weight ◽  
Acute Pain ◽  
High Frequency ◽  
Video Recording ◽  
Low Frequency ◽  
Peak Frequency ◽  
Analysis Software ◽  
Chi Square ◽  
Behavioral Indicators ◽  
Treatment Groups

Abstract Castration without the use of analgesia is routinely performed on male piglets. The objective of this study was to assess acute pain during castration through behavioral indicators. Piglets (n=88) were randomly allocated to one of two treatments: castration without the use of analgesia (C) and sham-castration (S). Within 24 hours after birth (birth weight = 1.78kg ±0.71), identical procedures were followed for both treatment groups, except sham piglets were not castrated. Struggle behavior (curl ups, leg kicks, and body flailing) and vocalizations were collected via continuous video recording as piglets received treatment from start (first application of scalpel) to end (application of iodine). Vocalization parameters (duration and peak frequency) were analyzed using the Raven Pro: Interactive Sound Analysis Software (Version 1.5). Peak frequency was defined as low (&lt; 1000 Hz) and high (≥ 1000 Hz). Data were analyzed using the Glimmix Procedure of SAS. For struggle behavior, treatment did not affect curl up frequency. However, castrated piglets kicked more frequently than did sham piglets (C=28.8±0.9 vs. S=21.3±0.9 kicks/min; P=0.02). Additionally, 52% of castrated piglets displayed body flailing, whereas only 4.4% of sham piglets displayed the same behavior (Chi-Square = 24.2; P &lt; 0.0001). For vocalizations, no difference was found for duration and peak frequency of low frequency calls. However, castrated piglets responded with more high frequency calls than sham piglets (C=23.6±0.3 vs. S=18.6±0.3 calls/min; P=0.04). High frequency calls tended to be of longer duration for castrated piglets (C=0.45±0.04 vs. S=0.27±0.04 sec/call; P=0.08). Results indicate that castration without the use of analgesia increased the frequency of leg kicks, body failing, and high frequency calls. This suggests that leg kicks, body flailing, and high frequency calls maybe useful behavioral indicators of acute pain in piglets.

A waveform inversion technique for measuring elastic wave attenuation in cylindrical bars

Geophysics ◽  
1992 ◽  
Vol 57 (6) ◽  
pp. 854-859 ◽  
Author(s):  
Xiao Ming Tang
Keyword(s):  
Elastic Wave ◽  
Wave Attenuation ◽  
Waveform Inversion ◽  
Finite Size ◽  
Low Frequency ◽  
Frequency Range ◽  
Multiple Reflections ◽  
Low Frequencies ◽  
The Time Domain ◽  
Attenuation Values

A new technique for measuring elastic wave attenuation in the frequency range of 10–150 kHz consists of measuring low‐frequency waveforms using two cylindrical bars of the same material but of different lengths. The attenuation is obtained through two steps. In the first, the waveform measured within the shorter bar is propagated to the length of the longer bar, and the distortion of the waveform due to the dispersion effect of the cylindrical waveguide is compensated. The second step is the inversion for the attenuation or Q of the bar material by minimizing the difference between the waveform propagated from the shorter bar and the waveform measured within the longer bar. The waveform inversion is performed in the time domain, and the waveforms can be appropriately truncated to avoid multiple reflections due to the finite size of the (shorter) sample, allowing attenuation to be measured at long wavelengths or low frequencies. The frequency range in which this technique operates fills the gap between the resonant bar measurement (∼10 kHz) and ultrasonic measurement (∼100–1000 kHz). By using the technique, attenuation values in a PVC (a highly attenuative) material and in Sierra White granite were measured in the frequency range of 40–140 kHz. The obtained attenuation values for the two materials are found to be reliable and consistent.

Methods to isolate retrograde and prograde Rayleigh-wave signals

2019 ◽  
Vol 219 (2) ◽  
pp. 975-994 ◽  
Author(s):  
Gabriel Gribler ◽  
T Dylan Mikesell
Keyword(s):  
Rayleigh Wave ◽  
Time Domain ◽  
Fundamental Mode ◽  
Poisson Ratio ◽  
Low Frequency ◽  
Wave Dispersion ◽  
Low Frequencies ◽  
Retrograde Motion ◽  
Mode Identification ◽  
Time Frequency

SUMMARY Estimating shear wave velocity with depth from Rayleigh-wave dispersion data is limited by the accuracy of fundamental and higher mode identification and characterization. In many cases, the fundamental mode signal propagates exclusively in retrograde motion, while higher modes propagate in prograde motion. It has previously been shown that differences in particle motion can be identified with multicomponent recordings and used to separate prograde from retrograde signals. Here we explore the domain of existence of prograde motion of the fundamental mode, arising from a combination of two conditions: (1) a shallow, high-impedance contrast and (2) a high Poisson ratio material. We present solutions to isolate fundamental and higher mode signals using multicomponent recordings. Previously, a time-domain polarity mute was used with limited success due to the overlap in the time domain of fundamental and higher mode signals at low frequencies. We present several new approaches to overcome this low-frequency obstacle, all of which utilize the different particle motions of retrograde and prograde signals. First, the Hilbert transform is used to phase shift one component by 90° prior to summation or subtraction of the other component. This enhances either retrograde or prograde motion and can increase the mode amplitude. Secondly, we present a new time–frequency domain polarity mute to separate retrograde and prograde signals. We demonstrate these methods with synthetic and field data to highlight the improvements to dispersion images and the resulting dispersion curve extraction.

Optimally Sensitive and Efficient Compact Loudspeakers for Low Audio Frequencies

2007 ◽  
Vol 38 (7) ◽  
pp. 11-17
Author(s):  
Ronald M. Aarts
Keyword(s):  
Optimality Criterion ◽  
Low Frequency ◽  
Audio Signal ◽  
Design Procedure ◽  
Frequency Range ◽  
Force Factor ◽  
Low Frequencies ◽  
Limited Frequency ◽  
The Cost ◽  
Higher Sensitivity

Conventionally, the ultimate goal in loudspeaker design has been to obtain a flat frequency response over a specified frequency range. This can be achieved by carefully selecting the main loudspeaker parameters such as the enclosure volume, the cone diameter, the moving mass and the very crucial “force factor”. For loudspeakers in small cabinets the results of this design procedure appear to be quite inefficient, especially at low frequencies. This paper describes a new solution to this problem. It consists of the combination of a highly non-linear preprocessing of the audio signal and the use of a so called low-force-factor loudspeaker. This combination yields a strongly increased efficiency, at least over a limited frequency range, at the cost of a somewhat altered sound quality. An analytically tractable optimality criterion has been defined and has been verified by the design of an experimental loudspeaker. This has a much higher efficiency and a higher sensitivity than current low-frequency loudspeakers, while its cabinet can be much smaller.

An Analytical Model for the Interaction of Mass Inclusions in Heterogeneous (HG) Blankets

2011 ◽  
Vol 133 (6) ◽  
Author(s):  
A. Wagner ◽  
M. E. Johnson ◽  
K. Idrisi ◽  
D. P. Bartylla
Keyword(s):  
Elastic Layer ◽  
Analytical Approach ◽  
Low Frequency ◽  
Control Device ◽  
Effective Stiffness ◽  
Special Focus ◽  
Dynamic Vibration Absorber ◽  
Low Frequencies ◽  
Dynamic Vibration ◽  
The Masses

The heterogeneous (HG) blanket is a passive treatment used to reduce the low frequency transmission of sound through partitions. HG blankets, glued onto a structure, consist of an elastic medium with embedded mass inhomogeneities that mechanically replicate a mass-spring-damper system to reduce efficient radiating structural modes at low frequencies. The elastic layer typically used has sound absorption properties to create a noise control device with a wide bandwidth of performance. The natural frequency of an embedded dynamic vibration absorber is determined by the mass of the inhomogeneity as well as by its effective stiffness due to the interaction of the mass inclusion with the elastic layer. A novel analytical approach has been developed to describe in detail the interaction of the mass inclusions with the elastic layer and the interaction between the masses by evaluating special elastomechanical concepts. The effective stiffness is predicted by the analytical approach based on the shape of the mass inclusions as well as on the thickness and material properties of the layer. The experimental validation is included and a simplified direct equation to calculate the effective stiffness of a HG blanket is proposed. Furthermore, the stress field inside the elastic material will be evaluated with focus on the stresses at the base to assess the modeling of one or more masses placed on top of the elastic layer as dynamic vibration absorbers. Finally, the interaction between two (or more) masses placed onto the same layer is studied with special focus on the coupling of the masses at low distances between them.

Measurement of Dynamic Strain

1943 ◽  
Vol 10 (2) ◽  
pp. A85-A92
Author(s):  
C. O. Dohrenwend ◽  
W. R. Mehaffey
Keyword(s):  
High Speed ◽  
Shock Loading ◽  
Low Frequency ◽  
Dynamic Strain ◽  
Time Axis ◽  
Low Frequencies ◽  
Strain Measurements ◽  
Moving Vehicles ◽  
Machine Parts ◽  
Dynamic Strains

Abstract The measurement of dynamic strains of both high and low frequency give rise to a variety of problems in instrumentation. Two types of equipment and circuits designed and used by the authors are discussed in detail. The first type based on the amplitude-modulated method is for low frequencies from zero to about 15 per cent of the carrier frequency of 1025 cycles per sec. The equipment has application to strain measurements varying from static values to those produced in moving vehicles, various machine parts, structures such as crane bridges, in fact all strain measurements where the frequency is 150 cycles per sec or less. The second type of equipment discussed is a potentiometer type and is for high-frequency strain measurements from 100 cycles per sec to 8000 cycles per sec. This high-speed equipment is conveniently used for impact strain, such as produced in hammer blows, shock loading, forging equipment, and impact-factor determination. Both units are designed to be used with a cathode-ray oscillograph which lends itself to a variety of recording methods. The methods discussed include both the type where the time axis is obtained by sweeping the oscilloscope beam on a stationary film and where the time axis is obtained mechanically.

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