Low-frequency sampling rates are effective to record bottlenose dolphins

Acoustic monitoring in cetacean studies is an effective but expensive approach. This is partly because of the high sampling rate required by acoustic devices when recording high-frequency echolocation clicks. However, the proportion of echolocation clicks recorded at different frequencies is unknown for many species, including bottlenose dolphins. Here, we investigated the echolocation clicks of two subspecies of bottlenose dolphins in the western South Atlantic Ocean. The possibility of recording echolocation clicks at 24 and 48 kHz was assessed by two approaches. First, we considered the clicks in the frequency range up to 96 kHz. We found a loss of 0.95–13.90% of echolocation clicks in the frequency range below 24 kHz, and 0.01–0.42% below 48 kHz, to each subspecies. Then, we evaluated these recordings downsampled at 48 and 96 kHz and confirmed that echolocation clicks are recorded at these lower frequencies, with some loss. Therefore, despite reaching high frequencies, the clicks can also be recorded at lower frequencies because echolocation clicks from bottlenose dolphins are broadband. We concluded that ecological studies based on the presence–absence data are still effective for bottlenose dolphins when acoustic devices with a limited sampling rate are used.

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Evaluation of Special Hearing Aids for Deaf Children

Journal of Speech and Hearing Disorders ◽

10.1044/jshd.3604.527 ◽

1971 ◽

Vol 36 (4) ◽

pp. 527-537 ◽

Cited By ~ 1

Author(s):

Norman P. Erber

Keyword(s):

Hearing Aids ◽

High Frequency ◽

Hearing Aid ◽

Low Frequency ◽

Acoustic Stimulation ◽

Deaf Children ◽

Frequency Range ◽

Frequency Limit ◽

Unpublished Studies ◽

Published Research

Two types of special hearing aid have been developed recently to improve the reception of speech by profoundly deaf children. In a different way, each special system provides greater low-frequency acoustic stimulation to deaf ears than does a conventional hearing aid. One of the devices extends the low-frequency limit of amplification; the other shifts high-frequency energy to a lower frequency range. In general, previous evaluations of these special hearing aids have obtained inconsistent or inconclusive results. This paper reviews most of the published research on the use of special hearing aids by deaf children, summarizes several unpublished studies, and suggests a set of guidelines for future evaluations of special and conventional amplification systems.

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Rheology of rounded mammalian cells over continuous high-frequencies

Nature Communications ◽

10.1038/s41467-021-23158-0 ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Gotthold Fläschner ◽

Cosmin I. Roman ◽

Nico Strohmeyer ◽

David Martinez-Martin ◽

Daniel J. Müller

Keyword(s):

High Frequency ◽

Mammalian Cells ◽

Mechanical Response ◽

Cell Mass ◽

Low Frequency ◽

Mass Measurements ◽

High Frequencies ◽

Polymer Relaxation ◽

Continuous Frequency ◽

Rheological Experiments

AbstractUnderstanding the viscoelastic properties of living cells and their relation to cell state and morphology remains challenging. Low-frequency mechanical perturbations have contributed considerably to the understanding, yet higher frequencies promise to elucidate the link between cellular and molecular properties, such as polymer relaxation and monomer reaction kinetics. Here, we introduce an assay, that uses an actuated microcantilever to confine a single, rounded cell on a second microcantilever, which measures the cell mechanical response across a continuous frequency range ≈ 1–40 kHz. Cell mass measurements and optical microscopy are co-implemented. The fast, high-frequency measurements are applied to rheologically monitor cellular stiffening. We find that the rheology of rounded HeLa cells obeys a cytoskeleton-dependent power-law, similar to spread cells. Cell size and viscoelasticity are uncorrelated, which contrasts an assumption based on the Laplace law. Together with the presented theory of mechanical de-embedding, our assay is generally applicable to other rheological experiments.

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An Improved Time Integration Method Based on Galerkin Weak Form with Controllable Numerical Dissipation

Applied Sciences ◽

10.3390/app11041932 ◽

2021 ◽

Vol 11 (4) ◽

pp. 1932

Author(s):

Weixuan Wang ◽

Qinyan Xing ◽

Qinghao Yang

Keyword(s):

High Frequency ◽

Integration Method ◽

Time Integration ◽

Low Frequency ◽

Weak Form ◽

High Accuracy ◽

Numerical Dissipation ◽

Frequency Range ◽

Time Integration Method ◽

Numerical Damping

Based on the newly proposed generalized Galerkin weak form (GGW) method, a two-step time integration method with controllable numerical dissipation is presented. In the first sub-step, the GGW method is used, and in the second sub-step, a new parameter is introduced by using the idea of a trapezoidal integral. According to the numerical analysis, it can be concluded that this method is unconditionally stable and its numerical damping is controllable with the change in introduced parameters. Compared with the GGW method, this two-step scheme avoids the fast numerical dissipation in a low-frequency range. To highlight the performance of the proposed method, some numerical problems are presented and illustrated which show that this method possesses superior accuracy, stability and efficiency compared with conventional trapezoidal rule, the Wilson method, and the Bathe method. High accuracy in a low-frequency range and controllable numerical dissipation in a high-frequency range are both the merits of the method.

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A Compact Four-Port Coplanar Antenna Based on an Excitation Switching Reconfigurable Mechanism for Cognitive Radio Applications

Applied Sciences ◽

10.3390/app9153157 ◽

2019 ◽

Vol 9 (15) ◽

pp. 3157 ◽

Cited By ~ 1

Author(s):

O ◽

Jin ◽

Choi

Keyword(s):

Cognitive Radio ◽

High Frequency ◽

Coplanar Waveguide ◽

Low Frequency ◽

Loop Antenna ◽

Ultra Wideband ◽

Frequency Range ◽

Uwb Antenna ◽

High Isolation ◽

Loop Antennas

In this paper, we propose a compact four-port coplanar antenna for cognitive radio applications. The proposed antenna consists of a coplanar waveguide (CPW)-fed ultra-wideband (UWB) antenna and three inner rectangular loop antennas. The dimensions of the proposed antenna are 42 mm × 50 mm × 0.8 mm. The UWB antenna is used for spectrum sensing and fully covers the UWB spectrum of 3.1–10.6 GHz. The three loop antennas cover the UWB frequency band partially for communication purposes. The first loop antenna for the low frequency range operates from 2.96 GHz to 5.38 GHz. The second loop antenna is in charge of the mid band from 5.31 GHz to 8.62 GHz. The third antenna operates from 8.48 GHz to 11.02 GHz, which is the high-frequency range. A high isolation level (greater than 17.3 dB) is realized among the UWB antenna and three loop antennas without applying any additional decoupling structures. The realized gains of the UWB antenna and three loop antennas are greater than 2.7 dBi and 1.38 dBi, respectively.

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Electromagnetic Property of La0.7Sr0.3MnO3/Ag Composite at High Frequency

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.655.182 ◽

2015 ◽

Vol 655 ◽

pp. 182-185

Author(s):

Ke Lan Yan ◽

Run Hua Fan ◽

Min Chen ◽

Kai Sun ◽

Xu Ai Wang ◽

...

Keyword(s):

High Frequency ◽

Single Phase ◽

Low Frequency ◽

Electromagnetic Property ◽

High Frequency Range ◽

Frequency Range ◽

Free Electron Concentration ◽

Theoretical Simulation ◽

Electrical And Magnetic Properties ◽

Three Phase

The phase structure, and electrical and magnetic properties of La0.7Sr0.3MnO3(LSMO)-xAg (xis the mole ratio,x=0, 0.3, 0.5) composite were investigated. It is found that the sample withx=0 is single phase; the samples withx=0.3 and 0.5 present three phase composite structure of the manganese oxide and Ag. With the increasing of Ag content, the grain size of the samples increases and the grain boundaries transition from fully faceted to partially faceted. The permittivity of spectrum (10 MHz - 1 GHz) and the theoretical simulation reveal that the plasma frequencyfpincrease with Ag content, due to the increasing of free electron concentration, which is further supported by the enhancement of conductivity. While for the permeability (μr'), theμr'decrease with the increasing of Ag content at low frequency range (f< 20 MHz), while at the relative high frequency range (f> 300 MHz), theμr'increased with Ag content. Therefore, the introduction of elemental Ag resulted in a higherμr'at the relative high frequency range.

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Anderson-Stuart Model to Analyze AC and DC Conductivity of Lithium Zinc-Silicate Glass / Glass-Ceramics

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.280-283.919 ◽

2007 ◽

Vol 280-283 ◽

pp. 919-924

Author(s):

M.S. Jogad ◽

V.K. Shrikhande ◽

A.H. Dyama ◽

L.A. Udachan ◽

Govind P. Kothiyal

Keyword(s):

High Frequency ◽

Glass Ceramics ◽

Low Frequency ◽

Frequency Region ◽

Dc Conductivity ◽

Frequency Range ◽

High Frequency Region ◽

Dc Conductivities ◽

Conductivity Variation ◽

Different Temperatures

AC and DC conductivities have been measured by using the real (e¢) and imaginary (e¢¢) parts of the dielectric constant data of glass and glass-ceramics (GC) at different temperatures in the rage 297-642K and in the frequency range 100 Hz to 10 MHz. Using Anderson –Stuart model, we have calculated the activation energy, which is observed to be lower than that of the DC conductivity. The analysis for glass/glass-ceramics indicates that the conductivity variation with frequency exhibits an initial linear region followed by nonlinear region with a maximum in the high-frequency region. The observed frequency dependence of ionic conductivity has been analyzed within the extended Anderson–Stuart model considering both the electrostatic and elastic strain terms. In glass/glassceramic the calculations based on the Anderson-Stuart model agree with the experimental observations in the low frequency region but at higher frequencies there is departure from measured data.

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High sampling rate thermistor string observations at the slope of Great Meteor Seamount

Ocean Science ◽

10.5194/os-1-17-2005 ◽

2005 ◽

Vol 1 (1) ◽

pp. 17-28 ◽

Cited By ~ 16

Author(s):

H. van Haren ◽

R. Groenewegen ◽

M. Laan ◽

B. Koster

Keyword(s):

High Frequency ◽

North Atlantic Ocean ◽

Sampling Rate ◽

Very High Frequency ◽

High Sampling ◽

High Sampling Rate ◽

In Situ Calibration ◽

Great Meteor Seamount ◽

Very High

Abstract. A high sampling rate (1 Hz) thermistor string has been built to accommodate the scientific need to accurately monitor high-frequency and vigorous internal wave and overturning processes in the ocean. The thermistors and their custom designed electronics can register temperature at an estimated precision of about 0.001° C with a response time faster than 0.25 s down to depths of 6000 m. With a quick in situ calibration using SBE 911 CTD an absolute accuracy of 0.005° C is obtained. The present string holds 128 sensors at 0.5 m intervals, which are all read-out within 0.5 s. When sampling at 1 Hz, the batteries and the memory capacity of the recorder allow for deployments of up to 2 weeks. In this paper, the instrument is described in some detail. Its performance is illustrated with examples from the first moored observations, which show Kelvin-Helmholtz overturning and very high-frequency (Doppler-shifted) internal waves besides occasionally large turbulent bores moving up the sloping side of Great Meteor Seamount, Canary Basin, North-Atlantic Ocean.

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ANALYSIS OF HIGH-FREQUENCY C-CORE MAGNETIC FLUX LEAKAGES FOR BONE TUMOR WITH INDUCTION HEATING BY USING MULTI-COIL

Proceedings 17th International Conference on Microwave and High Frequency Heating ◽

10.4995/ampere2019.2019.9900 ◽

2019 ◽

Author(s):

Metharak Jokpudsa ◽

Supawat Kotchapradit ◽

Chanchai Thongsopa ◽

Thanaset Thosdeekoraphat

Keyword(s):

Magnetic Field ◽

High Frequency ◽

Tumor Tissue ◽

Low Frequency ◽

Heat Energy ◽

High Frequencies ◽

Frequency Magnetic Field ◽

High Frequency Magnetic Field ◽

The Magnetic Field ◽

Flux Leakage

High-frequency magnetic field has been developed pervasively. The induction of heat from the magnetic field can help to treat tumor tissue to a certain extent. Normally, treatment by the low-frequency magnetic field needed to be combined with magnetic substances. To assist in the induction of magnetic fields and reduce flux leakage. However, there are studies that have found that high frequencies can cause heat to tumor tissue. In this paper present, a new magnetic application will focus on the analysis of the high-frequency magnetic nickel core with multi-coil. In order to focus the heat energy using a high-frequency magnetic field into the tumor tissue. The magnetic coil was excited by 915 MHz signal and the combination of tissues used are muscle, bone, and tumor. The magnetic power on the heating predicted by the analytical model, the power loss density (2.98e-6 w/m3) was analyzed using the CST microwave studio.

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Shallow subsurface mapping by electromagnetic sounding in the 300 kHz to 30 MHz range: Model studies and prototype system assessment

Geophysics ◽

10.1190/1.1443678 ◽

1994 ◽

Vol 59 (8) ◽

pp. 1201-1210 ◽

Cited By ~ 27

Author(s):

Duff C. Stewart ◽

Walter L. Anderson ◽

Thomas P. Grover ◽

Victor F. Labson

Keyword(s):

Dielectric Permittivity ◽

High Frequency ◽

Low Frequency ◽

Computer Programs ◽

Thin Layers ◽

Depth Range ◽

Frequency Range ◽

Model Studies ◽

New Instrument ◽

Displacement Currents

A new instrument designed for frequency‐domain sounding in the depth range 0–10 m uses short coil spacings of 5 m or less and a frequency range of 300 kHz to 30 MHz. In this frequency range, both conduction currents (controlled by electrical conductivity) and displacement currents (controlled by dielectric permittivity) are important. Several surface electromagnetic survey systems commonly used (generally with frequencies less than 60 kHz) are unsuitable for detailed investigation of the upper 5 m of the earth or, as with ground‐penetrating radar, are most effective in relatively resistive environments. Most computer programs written for interpretation of data acquired with the low‐frequency systems neglect displacement currents, and are thus unsuited for accurate high‐frequency modeling and interpretation. New forward and inverse computer programs are described that include displacement currents in layered‐earth models. The computer programs and this new instrument are used to evaluate the effectiveness of shallow high‐frequency soundings based on measurement of the tilt angle and the ellipticity of magnetic fields. Forward model studies indicate that the influence of dielectric permittivity provides the ability to resolve thin layers, especially if the instrument frequency range can be extended to 50 MHz. Field tests of the instrument and the inversion program demonstrate the potential for detailed shallow mapping wherein both the resistivity and the dielectric permittivity of layers are determined. Although data collection and inversion are much slower than for low‐frequency methods, additional information is obtained inasmuch as there usually is a permittivity contrast as well as a resistivity contrast at boundaries between different materials. Determination of dielectric permittivity is particularly important for hazardous waste site characterization because the presence of some contaminants may have little effect on observed resistivity but a large effect on observed permittivity.

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Fluctuating boundary layer on a magnetized plate

Mathematical Proceedings of the Cambridge Philosophical Society ◽

10.1017/s0305004100041463 ◽

1967 ◽

Vol 63 (2) ◽

pp. 513-525 ◽

Cited By ~ 11

Author(s):

Sahib Singh Chawla

Keyword(s):

Boundary Layer ◽

Low Frequency ◽

Surface Current ◽

Frequency Range ◽

Mean Flow ◽

Wave Type ◽

High Frequencies ◽

Phase Lead ◽

The Mean ◽

The Magnetic Field

The laminar boundary layer on a magnetized plate, when the magnetic field oscillates in magnitude about a constant non-zero mean, is analysed. For low-frequency fluctuations the solution is obtained by a series expansion in terms of a frequency parameter, while for high frequencies the flow pattern is of the ‘skin-wave’ type unaffected by the mean flow. In the low-frequency range, the phase lead and the amplitude of the skin-friction oscillations increase at first and then decrease to their respective ‘skin-wave’ values. On the other hand the phase angle of the surface current decreases from 90° to 45° and its amplitude increases with frequency.

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