Low‐frequency Arctic reverberation. I: Measurement of under‐ice backscattering strengths from short‐range direct‐path returns

1993 ◽  
Vol 93 (5) ◽  
pp. 2517-2523 ◽  
Author(s):  
T. J. Hayward ◽  
T. C. Yang
Keyword(s):  
Short Range ◽  
Low Frequency ◽  
Direct Path

Vibratory communication signal produced by male western conifer seed bugs (Hemiptera: Coreidae)

2008 ◽  
Vol 140 (2) ◽  
pp. 174-183
Author(s):  
Stephen Takács ◽  
Karl Hardin ◽  
Gerhard Gries ◽  
Ward Strong ◽  
Robb Bennett
Keyword(s):  
Short Range ◽  
Field Experiments ◽  
Lodgepole Pine ◽  
Low Frequency ◽  
Wide Band ◽  
Communication Signal ◽  
Vibratory Signal ◽  
Conifer Seed ◽  
Membrane Type ◽  
Piezoelectric Devices

AbstractWe tested the hypothesis that the western conifer seed bug, Leptoglossus occidentalis Heidemann, uses a substrate-borne vibratory signal for short-range communication. To record such a signal we used computers equipped with data-acquisition hardware and software, microphones sensitive to sonic and (or) ultrasonic frequencies, membrane-type and piezoelectric speakers capable of emitting sonic and ultrasonic sound, and piezoelectric devices capable of emitting low-level, low-frequency vibrations. By tapping their abdomen on substrate, males produced a wide-band vibratory signal 20 dB (sound pressure level; 0 dB = 20 µPa) above ambient sound, with dominant frequencies of 115 ± 10 and 175 ± 15 Hz and a distinct temporal pattern. There was no evidence for (i) ultrasonic signal components; (ii) signals produced by females or nymphs, or (iii) repeated trains of signal pulses. In two-choice arena experiments, males and females preferred the played-back recording of the male-produced substrate-borne signal over silent controls, whereas nymphs showed no preference for either stimulus. In two-choice dowel experiments with hickory wood or lodgepole pine crossbeams, females (unlike males or nymphs) preferred played-back recordings of the same signal over controls. In two-choice field experiments, this signal emitted in the air by piezoelectric devices or transferred through a wire to lodgepole pine branches attracted more L. occidentalis than did silent controls. Our data support the hypothesis that L. occidentalis uses a substrate-borne vibratory signal for short-range communication. The use of such a signal is consistent with reports on communication by other true bug species.

Masking of low frequency information in short-range apparent motion

1990 ◽  
Vol 30 (2) ◽  
pp. 317-327 ◽  
Author(s):  
Robert Cleary ◽  
Oliver J. Braddick
Keyword(s):  
Apparent Motion ◽  
Short Range ◽  
Low Frequency ◽  
Frequency Information

Investigations in Short-Range Seismic Propagation

1983 ◽  
Vol 2 (1) ◽  
pp. 12-19 ◽  
Author(s):  
R.F. Powell ◽  
M.R. Clay
Keyword(s):  
Seismic Noise ◽  
Short Range ◽  
Environmental Problem ◽  
Low Frequency ◽  
Seismic Source ◽  
Seismic Signal ◽  
Complex Nature ◽  
Seismic Propagation

The detection and location of a low-frequency seismic source is an increasingly significant environmental problem which is made more difficult by the complex nature of a seismic signal and the effect on it of ground transmission. The topic is discussed here in the context of augmenting a conventional undergraduate course in introductory waves and vibrations. Investigations are made of the geophone as a detector, the problem of seismic noise, the variation of seismic signatures with range and their interpretation, and a simple array for source direction.

A Model for the Mechanisms of Charge Transport Controlled by the Short-range Mobility

2013 ◽  
Vol 1556 ◽  
Author(s):  
Valerio Dallacasa
Keyword(s):  
Charge Transport ◽  
Working Conditions ◽  
Short Range ◽  
Low Frequency ◽  
Harmonic Oscillation ◽  
Zno Nanowires ◽  
Sound Waves ◽  
Transport Parameters ◽  
Oscillation Modes ◽  
Piezoelectric Fields

ABSTRACTStudies of carrier motion in a variety of nanostructures have indicated that a modified Drude model can be applied, by considering carrier bound motion from backscattering mechanisms and localized oscillator modes. Based on the results of these studies a model of damped harmonic oscillation modes is suggested to evaluate transport parameters in piezotronic devices. Here, the case of a system subject to static and low frequency piezoelectric fields is considered which corresponds to typical working conditions of nanogenerators and, as a working example, the response of ZnO nanowires excited by sound waves is analyzed.

Vibrational Raman spectra of liquid and solid ethylene

1970 ◽  
Vol 48 (5) ◽  
pp. 513-520 ◽  
Author(s):  
S. M. Blumenfeld ◽  
S. Paddi Reddy ◽  
H. L. Welsh
Keyword(s):  
Crystal Structure ◽  
Raman Spectrum ◽  
Force Constant ◽  
Raman Spectra ◽  
Short Range ◽  
Short Range Order ◽  
Freezing Point ◽  
Low Frequency ◽  
Intermolecular Force ◽  
Linear Dispersion

The Raman spectra of liquid and solid C2H4 have been examined at a reciprocal linear dispersion of 8 cm−1/mm. The liquid spectrum presents some evidence of short-range order in the liquid near the freezing point. The gerade fundamentals and low-frequency librational modes have been observed in the Raman spectrum of the solid. Analysis of the observed splitting in terms of H-atom repulsion indicates that the intermolecular force constant is 950 dyn/cm, and the crystal structure is P21/n1. The origin of other observed structures is uncertain.

scholarly journals Machine Learning Classification of Mild Traumatic Brain Injury Using Whole-Brain Functional Activity: A Radiomics Analysis

2021 ◽  
Vol 2021 ◽  
pp. 1-7
Author(s):  
Xiaoping Luo ◽  
Dezhao Lin ◽  
Shengwei Xia ◽  
Dongyu Wang ◽  
Xinmang Weng ◽  
...  
Keyword(s):  
Traumatic Brain Injury ◽  
Brain Injury ◽  
Mild Traumatic Brain Injury ◽  
Short Range ◽  
Low Frequency ◽  
Brain Regions ◽  
Classification Performance ◽  
Imaging Parameters ◽  
The Brain ◽  
Normal Controls

Objectives. To investigate the classification performance of support vector machine in mild traumatic brain injury (mTBI) from normal controls. Methods. Twenty-four mTBI patients (15 males and 9 females; mean age, 38.88 ± 13.33 years) and 24 age and sex-matched normal controls (13 males and 11 females; mean age, 40.46 ± 11.4 years) underwent resting-state functional MRI examination. Seven imaging parameters, including amplitude of low-frequency fluctuation (ALFF), fractional amplitude of low-frequency fluctuation (fALFF), regional homogeneity (ReHo), degree centrality (DC), voxel-mirrored homotopic connectivity (VMHC), long-range functional connectivity density (FCD), and short-range FCD, were entered into the classification model to distinguish the mTBI from normal controls. Results. The ability for any single imaging parameters to distinguish the two groups is lower than multiparameter combinations. The combination of ALFF, fALFF, DC, VMHC, and short-range FCD showed the best classification performance for distinguishing the two groups with optimal AUC value of 0.778, accuracy rate of 81.11%, sensitivity of 88%, and specificity of 75%. The brain regions with the highest contributions to this classification mainly include bilateral cerebellum, left orbitofrontal cortex, left cuneus, left temporal pole, right inferior occipital cortex, bilateral parietal lobe, and left supplementary motor area. Conclusions. Multiparameter combinations could improve the classification performance of mTBI from normal controls by using the brain regions associated with emotion and cognition.

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