Calling-song function in male haglids (Orthoptera: Haglidae, Cyphoderris)

2002 ◽  
Vol 80 (2) ◽  
pp. 271-285 ◽  
Author(s):  
Glenn K Morris ◽  
Paul A DeLuca ◽  
Matthew Norton ◽  
Andrew C Mason
Keyword(s):  
Pulse Rate ◽  
Duty Cycle ◽  
Site Fidelity ◽  
Field Experiments ◽  
Low Frequency ◽  
Calling Song ◽  
Large Cage ◽  
Cycle Plays ◽  
Relative Attractiveness ◽  
Lone Male

We studied the response of males to the singing of nearby male conspecifics in two species of the orthopteran genus Cyphoderris, primitive relatives of crickets and katydids. Lone male Cyphoderris buckelli stridulating in a large cage made a phonotactic approach to a nearby speaker broadcasting conspecific calling song. But in field experiments no phonotaxis to song broadcasts occurred; rather, a significant number of male C. buckelli increased their chirp duty cycle and pulse rate. There was no change in their carrier frequency. Calling male Cyphoderris monstrosa were exposed in the field to (i) playback of a synthetic calling song at a typical conspecific pulse rate, (ii) relayed broadcast of their own call, and (iii) low-frequency audio noise. Call duty cycle decreased significantly in response to the noise, while the pooled song models fell just short of significance. Singing C. buckelli were marked individually and their perches flagged over successive nights. We observed low site fidelity and extensive male displacement. Such behaviour is inconsistent with defense of topographically fixed singing territories and concurs with the absence of fighting in this species. Chirp duty cycle was increased significantly in C. buckelli in response to the singing of nearby conspecifics, but unlike in C. monstrosa, this change in duty cycle plays no role in overt aggression, though it may maintain a male's relative attractiveness to females.

Low Frequency of Site Fidelity by Golden-Fronted Woodpeckers

2002 ◽  
Vol 47 (1) ◽  
pp. 110 ◽  
Author(s):  
Michael S. Husak ◽  
Jerry F. Husak
Keyword(s):  
Site Fidelity ◽  
Low Frequency

IP interpretation in environmental investigations

Geophysics ◽  
2002 ◽  
Vol 67 (1) ◽  
pp. 77-88 ◽  
Author(s):  
Lee D. Slater ◽  
David Lesmes
Keyword(s):  
Field Experiments ◽  
Low Frequency ◽  
Environmental Parameters ◽  
Clay Content ◽  
Chemistry Laboratory ◽  
Frequency Effect ◽  
Resistivity Method ◽  
Surface Polarization ◽  
Capacitive Properties ◽  
Diffusion Polarization

The induced polarization (IP) response of rocks and soils is a function of lithology and fluid conductivity. IP measurements are sensitive to the low‐frequency capacitive properties of rocks and soils, which are controlled by diffusion polarization mechanisms operating at the grain‐fluid interface. IP interpretation typically is in terms of the conventional field IP parameters: chargeability, percentage frequency effect, and phase angle. These parameters are dependent upon both surface polarization mechanisms and bulk (volumetric) conduction mechanisms. Consequently, they afford a poor quantification of surface polarization processes of interest to the field geophysicist. A parameter that quantifies the magnitude of surface polarization is the normalized chargeability, defined as the chargeability divided by the resistivity magnitude. This parameter is proportional to the quadrature conductivity measured in the complex resistivity method. For nonmetallic minerals, the quadrature conductivity and normalized chargeability are closely related to lithology (through the specific surface area) and surface chemistry. Laboratory and field experiments were performed to determine the dependence of the standard IP parameters and the normalized chargeability on two important environmental parameters: salinity and clay content. The laboratory experiments illustrate that the chargeability is strongly correlated with the sample resistivity, which depends on salinity, porosity, saturation, and clay content. The normalized chargeability is shown to be independent of the sample resistivity and it is proportional to the quadrature conductivity, which is directly related to the surface polarization processes. Laboratory‐derived relationships between conductivity and salinity, and normalized chargeability and clay content, are extended to the interpretation of 1‐D and 2‐D field‐IP surveys. In the 2‐D survey, the apparent conductivity and normalized chargeability data are used to segment the images into relatively clay‐free and clay‐rich zones. A similar approach can eventually be used to predict relative variations in the subsurface clay content, salinity and, perhaps, contaminant concentrations.

scholarly journals Refactoring and Optimization of Bridge Dynamic Displacement Based on Ensemble Empirical Mode Decomposition

Sensors ◽  
2019 ◽  
Vol 19 (14) ◽  
pp. 3125
Author(s):  
Zou ◽  
Chen ◽  
Liu
Keyword(s):  
Empirical Mode Decomposition ◽  
Field Experiments ◽  
Low Frequency ◽  
Vibration Signal ◽  
Micro Electro Mechanical System ◽  
Ensemble Empirical Mode Decomposition ◽  
Reconstruction Method ◽  
Monitoring Methods ◽  
Dynamic Displacement ◽  
Mode Decomposition

Considering the lack of precision in transforming measured micro-electro-mechanical system (MEMS) accelerometer output signals into elevation signals, this paper proposes a bridge dynamic displacement reconstruction method based on the combination of ensemble empirical mode decomposition (EEMD) and time domain integration, according to the vibration signal traits of a bridge. Through simulating bridge analog signals and verifying a vibration test bench, four bridge dynamic displacement monitoring methods were analyzed and compared. The proposed method can effectively eliminate the influence of low-frequency integral drift and high-frequency ambient noise on the integration process. Furthermore, this algorithm has better adaptability and robustness. The effectiveness of the method was verified by field experiments on highway elevated bridges.

Mechanical and metabolic alterations in rat diaphragm during electrical stimulation

1989 ◽  
Vol 67 (1) ◽  
pp. 210-220 ◽  
Author(s):  
P. S. Massarelli ◽  
H. J. Green ◽  
R. L. Hughson ◽  
M. T. Sharratt
Keyword(s):  
Duty Cycle ◽  
Adenine Nucleotide ◽  
Isometric Force ◽  
Low Frequency ◽  
Maximal Velocity ◽  
Force Output ◽  
Experimental Conditions ◽  
Adult Rats ◽  
Male Adult ◽  
Fatigue Development

To investigate the hypothesis that the rate of fatigue development is not influenced by the absolute duration of contraction (train duration) and relaxation (off-phase of duty cycle) at constant duty cycle, strips of the diaphragm from 36 male adult rats (mean +/- SD wt 152 +/- 21 g) were stimulated directly for periods of 180, 250, and 320 ms at a constant duty cycle of 50%. The frequency of stimulation was adjusted to produce 40% of maximal tetanic tension at supramaximal voltages. After 30 min of stimulation, analysis of twitch characteristics between control and experimental groups indicated a prolongation of contraction time of 9% (P less than 0.05), an increase in relaxation time of 75% (P less than 0.05), and a decrease in twitch tension by 78% (P less than 0.05). Similarly, reductions (P less than 0.05) in isometric force output at high stimulation frequency (100 Hz) of 58% and at low frequency (20 Hz) of 67% were also noted. These changes were accompanied by an approximately 60% reduction in the maximal velocity of shortening. No difference was observed for any of the mechanical measures between experimental conditions. After 30-min stimulation, decreases of between 43 and 46% were noted for ATP (P less than 0.05) and increases of between three- and fourfold noted for IMP (P less than 0.05). No changes were found for either ADP or AMP. Total adenine nucleotide concentrations declined (P less than 0.05) an average of 24%. As with the mechanical data, no differences were found between the different stimulation conditions. It is concluded that for the conditions studied, fatigue mechanisms become manifest early in the stimulation period and are only minimally altered by the duration of specific contractions provided the relaxation period is of equal duration.

scholarly journals An Extraction Method of Weak Low-Frequency Magnetic Communication Signals Based on Multisensor

2015 ◽  
Vol 2015 ◽  
pp. 1-8
Author(s):  
Chao Huang ◽  
Xin Xu ◽  
Dunge Liu ◽  
Wanhua Zhu ◽  
Xiaojuan Zhang ◽  
...  
Keyword(s):  
Blind Source Separation ◽  
Extraction Method ◽  
Field Experiments ◽  
Signal To Noise Ratio ◽  
Source Separation ◽  
Low Frequency ◽  
Signal Extraction ◽  
Magnetic Noise ◽  
Communication Signals ◽  
Low Snr

It is a technical challenge to effectively remove the influence of magnetic noise from the vicinity of the receiving sensors on low-frequency magnetic communication. The traditional denoising methods are difficult to extract high-quality original signals under the condition of low SNR (the signal-to-noise ratio). In this paper, we analyze the numerical characteristics of the low-frequency magnetic field and propose the algorithms of the fast optimization of blind source separation (FOBSS) and the frequency-domain correlation extraction (FDCE). FOBSS is based on blind source separation (BSS). Signal extraction of low SNR can be implemented through FOBSS and FDCE. This signal extraction method is verified in multiple field experiments which can remove the magnetic noise by about 25 dB or more.

Parasitism of House Wren nests by Brown-headed Cowbirds: why is it so rare?

1997 ◽  
Vol 75 (2) ◽  
pp. 302-307 ◽  
Author(s):  
Stanislav Pribil ◽  
Jaroslav Picman
Keyword(s):  
Field Experiments ◽  
Molothrus Ater ◽  
Low Frequency ◽  
Nest Material ◽  
Nest Structure ◽  
Troglodytes Aedon ◽  
House Wren ◽  
House Wrens ◽  
Nest Desertion ◽  
Cowbird Parasitism

We tested five hypotheses that may explain why House Wren (Troglodytes aedon) nests are rarely parasitized by Brown-headed Cowbirds (Molothrus ater). House Wrens may prevent parasitism in five ways: (1) by choosing to nest in cavities with small entrances (inaccessible-entrance hypothesis), (2) by restricting the size of the entrance with nest material (nest-structure hypothesis), (3) by puncturing and ejecting parasitic eggs (puncture–ejection hypothesis), (4) by burying the parasitized clutch under a new nest (egg-burial hypothesis), or (5) by abandoning the parasitized nest altogether (nest-desertion hypothesis). We tested these hypotheses in field experiments and found that (i) female cowbirds cannot enter circular entrances smaller than 38 mm in diameter, (ii) wrens prefer cavities with small entrances (inaccessible to cowbirds) to those with large entrances (accessible to cowbirds), (iii) when forced to breed in cavities with large entrances, wrens do not reduce the entrance size with nest material, (iv) despite the unusual strength of cowbird eggs, wrens are physically capable of puncture–ejecting them, (v) wrens do not puncture–eject cowbird eggs from their own nests, (vi) wrens do not abandon parasitized nests or bury the parasitized clutches under new nests. These results are consistent with the inaccessible-entrance hypothesis. We propose that additional nesting adaptations, as well as active cowbird avoidance of House Wrens, may contribute to the low frequency of cowbird parasitism.

scholarly journals Low-frequency acoustic signal created by rising air-gun bubble

Geophysics ◽  
2017 ◽  
Vol 82 (6) ◽  
pp. P119-P128
Author(s):  
Daniel Wehner ◽  
Martin Landrø
Keyword(s):  
Acoustic Signal ◽  
Field Experiments ◽  
Waveform Inversion ◽  
Low Frequency ◽  
Frequency Signal ◽  
Low Frequencies ◽  
Air Bubble ◽  
Rising Bubble ◽  
Air Gun ◽  
Different Depths

In the seismic industry, there is increasing interest in generating and recording low frequencies, which leads to better data quality and can be important for full-waveform inversion. The air gun is a seismic source with a signal that consists of the (1) main impulse, (2) oscillating bubble, and (3) rising of this air bubble. However, there has been little investigation of the third characteristic. We have studied a low-frequency signal that could be created by the rising air bubble and find the contribution to the low-frequency content in seismic acquisition. We use a simple theory and modeling of rising spheres in water and compute the acoustic signal created by this effect. We conduct tank and field experiments with a submerged buoy that is released from different depths and record the acoustic signal with hydrophones along the rising path. The experiments simulate the signal from the rising bubble separated from the other two effects (1 and 2). Furthermore, we use data recorded below a single air gun fired at different depths to investigate if we can observe the proposed signal. We find that the rising bubble creates a low-frequency signal. Compared with the main impulse and the oscillating bubble effect of an air-gun signal, the contribution of the rising bubble is weak, on the order of 1/900 depending on the bubble size. By using large air-gun arrays tuned to create one big bubble, the contribution of the signal can be increased. The enhanced signal can be important for deep targets or basin exploration because the low-frequency signal is less attenuated.

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