Long-distance, low-frequency elephant communication

2004 ◽  
Vol 190 (10) ◽  
pp. 791-805 ◽  
Author(s):  
Michael Garstang
Keyword(s):  
Low Frequency ◽  
Long Distance

scholarly journals Variation of Low-Frequency Time-Code Signal Field Strength during the Annular Solar Eclipse on 21 June 2020: Observation and Analysis

Sensors ◽  
2021 ◽  
Vol 21 (4) ◽  
pp. 1216
Author(s):  
Xin Wang ◽  
Bo Li ◽  
Fan Zhao ◽  
Xinyu Luo ◽  
Luxi Huang ◽  
...  
Keyword(s):  
Field Strength ◽  
Solar Eclipse ◽  
Low Frequency ◽  
Signal Propagation ◽  
Normal Operation ◽  
Time Code ◽  
Long Distance ◽  
Time Service ◽  
Annular Solar Eclipse ◽  
Signal Field

Due to the occlusion of the moon, an annular solar eclipse will have an effect on the ionosphere above the earth. The change of the ionosphere, for the low-frequency time-code signal that relies on it as a reflection medium for long-distance propagation, the signal field strength, and other parameters will also produce corresponding changes, which will affect the normal operation of the low-frequency time-code time service system. This paper selects the solar eclipse that occurred in China on 21 June 2020, and uses the existing measurement equipment to carry out experimental research on the low-frequency time-code signal. We measured and analyzed the signal field strength from 20 June 2020 to 23 June 2020, and combined solar activity data, ionospheric data, and geomagnetic data, and attempted to explore the reasons and rules of the change of signal parameters. The results showed that the field strength of the low-frequency time-code signal changed dramatically within a short time period, the max growth value can reach up to 17 dBμV/m and the variation trend yielded ‘three mutations’. This change in signal field strength is probably due to the occurrence of a solar eclipse that has an effect on the ionosphere. When the signal propagation conditions change, the signal strength will also change accordingly.

scholarly journals Cues, creaks, and decoys: using passive acoustic monitoring as a tool for studying sperm whale depredation

2015 ◽  
Vol 72 (5) ◽  
pp. 1621-1636 ◽  
Author(s):  
Aaron Thode ◽  
Delphine Mathias ◽  
Janice Straley ◽  
Victoria O'Connell ◽  
Linda Behnken ◽  
...  
Keyword(s):  
Low Frequency ◽  
Field Tests ◽  
Sperm Whale ◽  
Acoustic Monitoring ◽  
Sperm Whales ◽  
Passive Acoustic Monitoring ◽  
Long Distance ◽  
Fishing Activity ◽  
Fishing Vessels ◽  
Passive Acoustic

Abstract Since 2003, a collaborative effort (SEASWAP) between fishers, scientists, and managers has researched how Alaskan sperm whales locate demersal longline fishing activity and then depredate sablefish from gear. Sperm whales constantly produce relatively low-frequency biosonar signals whenever foraging; therefore, over the past decade, passive acoustic monitoring (PAM) has become a basic tool, used for both measuring depredation activity and accelerating field tests of potential depredation countermeasures. This paper reviews and summarizes past published PAM research on SEASWAP, and then provides a detailed example of how PAM methods are currently being used to test countermeasures. The review covers two major research thrusts: (i) identifying acoustic outputs of fishing vessels that provide long-distance “cues” that attract whales to fishing activity; and (ii) validating whether distinctive “creak” sounds can be used to quantify and measure depredation rates, using both bioacoustic tags and statistical comparisons between visual and acoustic depredation estimates during federal sablefish surveys. The latter part of the paper then provides an example of how PAM is being used to study a particular potential countermeasure: an “acoustic decoy” which transmits fishing vessel acoustic cues to attract animals away from true fishing activity. The results of an initial 2011 field trial are presented to show how PAM was used to design the decoy signals and monitor the efficacy of the deployment. The ability of PAM to detect both whale presence and depredation behaviour has reduced the need to deploy researchers or other specialists on fishing cruises. Instead, volunteer fishers can deploy “user-friendly” acoustic recorders on their gear, greatly facilitating the testing of various deterrents, and providing the industry and regulators a convenient and unobtrusive tool for monitoring both the scale and long-term spread of this behaviour across the Alaskan fishery.

scholarly journals Long-distance, low-frequency elephant communication

2005 ◽  
Vol 191 (3) ◽  
pp. 299-299
Author(s):  
Michael Garstang
Keyword(s):  
Low Frequency ◽  
Long Distance

A Graphene Chain Acts as a Long-Distance Ballistic Heat Conductor

2010 ◽  
Author(s):  
Koji Takahashi ◽  
Yohei Ito ◽  
Tatsuya Ikuta
Keyword(s):  
Thermal Conductivity ◽  
Carbon Nanofiber ◽  
Soft Drink ◽  
Three Dimensional ◽  
Low Frequency ◽  
Phonon Transport ◽  
Dynamics Simulation ◽  
Infinite Length ◽  
Unexpected Result ◽  
Long Distance

A carbon nanofiber material, consisting of bottomless graphene cups inside on each other in a line, like a set of soft-drink cups, has been discovered to have the potential to conduct heat ballistically over a long distance. Its longitudinal heat transport ability had been forecast to be extremely poor due to the weak van der Waals force operating between the graphene cups, but our measurements using nano thermal sensor showed that its thermal conductivity is much higher than that along the c-axis of bulk graphite. This unexpected result can be understood by its similarity to a one-dimensional (1D) harmonic-chain where no phonon is scattered even for an infinite length. The current graphene-based nanofiber resembles this type of “superconductive” chain due to the huge difference between the stiff covalent bonding in each cup and the weak inter-cup interaction. A non-equilibrium molecular dynamics simulation is conducted to explore the phonon transport in this fiber. The simulation results show that the thermal conductivity varies with the fiber length in a power law fashion with an exponent as large as 0.7. The calculated phonon density of states and atomic motions indicate that a low-frequency quasi-1D oscillation occurs there. Our investigations show that treating the current nanofiber as a 1D chain with three-dimensional oscillations explains well why this material has the most effective ballistic phonon transport ever observed.

scholarly journals Characteristics of Low-Frequency Acoustic Wave Propagation in Ice-Covered Shallow Water Environment

2021 ◽  
Vol 11 (17) ◽  
pp. 7815
Author(s):  
Shande Li ◽  
Shuai Yuan ◽  
Shaowei Liu ◽  
Jian Wen ◽  
Qibai Huang ◽  
...  
Keyword(s):  
Parabolic Equation ◽  
Target Detection ◽  
Acoustic Field ◽  
Sound Propagation ◽  
Transmission Loss ◽  
Low Frequency ◽  
Sound Field ◽  
The Arctic ◽  
Long Distance ◽  
Propagation Law

Mastering the sound propagation law of low-frequency signals in the Arctic is a major frontier basic research demand to improve the level of detection, communication, and navigation technology. It is of practical significance for long-distance sound propagation and underwater target detection in the Arctic Ocean. Therefore, how to establish an effective model to study the characteristics of the acoustic field in the Arctic area has always been a hot topic in polar acoustic research. Aimed at solving this problem, a mathematical polar acoustic field model with an elastic seafloor is developed based on a range-dependent elastic parabolic equation theory. Moreover, this method is applied to study the characteristics of polar sound propagation for the first attempt. The validity and effectiveness of the method and model are verified by the elastic normal mode method. Simultaneously, the propagation characteristics of low-frequency signals are studied in a polar sound field from three aspects, which are seafloor parameters, sea depth, and ice thickness. The results show that the elastic parabolic equation method can be well utilized to the Arctic low-frequency acoustic field. The analysis of the influence factors of the polar sound field reveals the laws of sound transmission loss of low-frequency signals, which is of great significance to provide information prediction for underwater submarine target detection and target recognition.

scholarly journals Long-distance syntactic dependencies drive the complexity of legal language

2021 ◽  
Author(s):  
Eric Martinez ◽  
Francis Mollica ◽  
Edward Gibson
Keyword(s):  
Low Frequency ◽  
Long Distance ◽  
Passive Voice ◽  
Reading Levels ◽  
Legal Documents ◽  
Embedded Clauses ◽  
Legal Concepts ◽  
Syntactic Dependencies ◽  
Center Embedding ◽  
Processing Difficulty

Although contracts and other legal documents have long been known to cause processing difficulty in laypeople, the source and nature of this difficulty has remained unclear. To better understand this mismatch, we conducted a corpus analysis (~10 million words) to investigate to what extent difficult-to-process features that are reportedly common in contracts--such as center embedding, low-frequency jargon, passive voice and non-standard capitalization--are in fact present in contracts relative to normal texts. We found that all of these features were strikingly more prevalent in contracts relative to standard-English texts. We also conducted an experimental study ($n=108$ subjects) to determine to what extent such features cause processing difficulties for laypeople of different reading levels. We found that contractual excerpts containing these features were recalled and comprehended at a lower rate than excerpts without these features, even for experienced readers, and that center-embedded clauses led to greater decreases in recall than other features. These findings confirm long-standing anecdotal accounts of the presence of difficult-to-process features in contracts, and show that these features inhibit comprehension and recall of legal content for readers of all levels. Our findings also suggest such difficulties may largely result from working memory costs imposed by complex syntactic features--such as center-embedded clauses--as opposed to a mere lack of understanding of specialized legal concepts, and that removing these features would be both tractable and beneficial for society at large.

scholarly journals THE MAIN CHARACTERISTICS AND FEATURES OF THE LOW-FREQUENCY WAVE PROCESS IN THE STRETCHED PIPELINES

2019 ◽  
pp. 5-23
Author(s):  
O. G. Bondarenko
Keyword(s):  
Solid Medium ◽  
Pipe Wall ◽  
Wave Process ◽  
Low Frequency ◽  
Technical Condition ◽  
The Body ◽  
Technical State ◽  
Long Distance ◽  
Pipe Surface ◽  
Frequency Wave

The problem of determining the technical condition of various pipeline systems, ensuring their reliable аnd safe operation has recently become the subject of geopolitics. In this situation, constant monitoring of their technical condition is essential for the maintenance of pipelines. However, it is technically difficult to monitor the technical state of pipelines by conventional methods of non-destructive testing (NDT). An analysis of the essence of the wave process in diagnosing the technical condition of long pipelines by low-frequency ultrasound directed waves is performed. The types of modes of directed waves and peculiarities of the wave process in the solid medium of the pipeline are given. Dispersed diagrams of  ound velocities for different modes of directed waves are considered, on the basis of which their main features are formulated in the diagnosis of the technical state of extended pipelines. The analysis of the wave process in the long pipeline from the position of the acoustic location of its solid medium by low-frequency directional waves is made, the model of the active localization system is developed in diagnosing the technical state of the pipeline, the principles of excitation and displacement of the particles of the medium of the pipe wall are considered in the distribution of longitudinal, twisted and bending mods of low-frequency ultrasonic directed waves. When choosing the frequency and mode of the directed wave to diagnose the technical state of long pipes, it is necessary to take into account that the directed wave is the result of the interaction of the vibrations generated by the transducers with the pipe surface. A significant factor determining the efficiency of energy transfer from the antenna to the body of the drainage pipeline is the harmonization of the internal resistance of the converter and the load due to the static force of pressing the piezoelectric transducers to the pipe surface. When creating systems of low-frequency ultrasonic diagnostics of long-distance pipelines directed waves it is necessary to take into account the main features of the wave process, which has a complicated mechanism of propagation over the thickness of the pipe wall.

scholarly journals Form and function of long-range vocalizations in a Neotropical fossorial rodent: the Anillaco Tuco-Tuco (Ctenomyssp.)

PeerJ ◽  
2016 ◽  
Vol 4 ◽  
pp. e2559 ◽  
Author(s):  
Juan Pablo Amaya ◽  
Juan I. Areta ◽  
Veronica S. Valentinuzzi ◽  
Emmanuel Zufiaurre
Keyword(s):  
Long Range ◽  
Vocal Communication ◽  
Broad Band ◽  
Low Frequency ◽  
Home Ranges ◽  
Subterranean Rodents ◽  
Acoustic Features ◽  
Long Distance ◽  
Form And Function ◽  
Types Of Information

The underground environment poses particular communication challenges for subterranean rodents. Some loud and low-pitched acoustic signals that can travel long distances are appropriate for long-range underground communication and have been suggested to be territorial signals. Long-range vocalizations (LRVs) are important in long-distance communication inCtenomystuco-tucos. We characterized the LRV of the Anillaco Tuco-Tuco (Ctenomyssp.) using recordings from free-living individuals and described the behavioral context in which this vocalization was produced during laboratory staged encounters between individuals of both sexes. Long-range calls of Anillaco tuco-tucos are low-frequency, broad-band, loud, and long sounds composed by the repetition of two syllable types: series (formed by notes and soft-notes) and individual notes. All vocalizations were initiated with series, but not all had individual notes. Males were heavier than females and gave significantly lower-pitched vocalizations, but acoustic features were independent of body mass in males. The pronounced variation among individuals in the arrangement and number of syllables and the existence of three types of series (dyads, triads, and tetrads), created a diverse collection of syntactic patterns in vocalizations that would provide the opportunity to encode multiple types of information. The existence of complex syntactic patterns and the description of soft-notes represent new aspects of the vocal communication ofCtenomys. Long-distance vocalizations by Anillaco Tuco-Tucos appear to be territorial signals used mostly in male-male interactions. First, emission of LRVs resulted in de-escalation or space-keeping in male-male and male-female encounters in laboratory experiments. Second, these vocalizations were produced most frequently (in the field and in the lab) by males in our study population. Third, males produced LRVs with greater frequency during male-male encounters compared to male-female encounters. Finally, males appear to have larger home ranges that were more spatially segregated than those of females, suggesting that males may have greater need for long-distance signals that advertise their presence. Due to their apparent rarity, the function and acoustic features of LRV in female tuco-tucos remain inadequately known.

scholarly journals Booming far: the long-range vocal strategy of a lekking bird

2017 ◽  
Vol 4 (8) ◽  
pp. 170594 ◽  
Author(s):  
C. Cornec ◽  
Y. Hingrat ◽  
T. Aubin ◽  
F. Rybak
Keyword(s):  
Long Range ◽  
Communication Networks ◽  
Second Harmonic ◽  
Natural Habitat ◽  
Low Frequency ◽  
Acoustic Signals ◽  
Long Distance ◽  
Sexual Competition ◽  
The North ◽  
Transmission Of Information

The pressures of selection acting on transmission of information by acoustic signals are particularly high in long-distance communication networks. Males of the North African houbara bustard ( Chlamydotis undulata undulata ) produce extremely low-frequency vocalizations called ‘booms’ as a component of their courtship displays. These displays are performed on sites separated by a distance of on average 550 m, constituting exploded leks. Here, we investigate the acoustic features of booms involved in species-specific identity. We first assessed the modifications of acoustic parameters during boom transmission at long range within the natural habitat of the species, finding that the frequency content of booms was reliably transmitted up to 600 m. Additionally, by testing males' behavioural responses to playbacks of modified signals, we found that the presence of the second harmonic and the frequency modulation are the key parameters for species identification, and also that a sequence of booms elicited stronger responses than a single boom. Thus, the coding–decoding process relies on redundant and propagation-resistant features, making the booms particularly well adapted for the long-range transmission of information between males. Moreover, by experimentally disentangling the presentation of visual and acoustic signals, we showed that during the booming phase of courtship, the two sensory modalities act in synergy. The acoustic component is dominant in the context of intra-sexual competition. While the visual component is not necessary to induce agonistic response, it acts as an amplifier and reduces the time of detection of the signaller. The utilization of these adaptive strategies allows houbara males to maximize the active space of vocalizations emitted in exploded leks.

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