scholarly journals The benefits of insect-swarm hunting in echolocating bats, and its influence on the evolution of bat echolocation signals

2019 ◽  
Author(s):  
Arjan Boonman ◽  
Yossi Yovel ◽  
Brock Fenton
Keyword(s):  
Computer Simulations ◽  
Visual Information ◽  
Prey Detection ◽  
Sound Waves ◽  
Echo Intensity ◽  
Open Spaces ◽  
Echolocation Calls ◽  
Operating Range ◽  
Collective Movement ◽  
Swarm Density

AbstractPredation on swarms of prey, especially using visual information, has drawn much interest in studies of collective movement. Surprisingly, in the field of biosonar this aspect of prey detection, which is probably very common, has received little to no attention. Here, we combine computer simulations and actual echo measurements to accurately estimate the echo intensity of insect swarms of different size and density. We show that swarm echo intensity increases with 3dB for every doubling of insect number, irrespective of swarm density. Thus swarms will be much easier to detect than single insects. Many of the insects bats eat are so small that they are only detectable by echolocation at very short distances. By focusing on detection of swarms of insects, a bat may increase its operating range and diversify its diet. Interestingly, interference between the sound waves reflected from a swarm of insects can sometimes result in echoes that are much much weaker than echoes from single insects. We show that bats can reduce this problem by increasing the bandwidth of their echolocation calls. Specifically, a bandwidth of 3-8 kHz would guarantee receiving loud echoes from any angle relative to the swarm. Indeed, many bat species, and specifically bats hunting in open spaces, where swarms are abundant, use echolocation signals with a bandwidth of several kHz. Our results might also explain how the first echolocating bats that probably had limited echolocation abilities, could detect insects through swarm hunting.

The Detection of Orientation of Small Objects

Perception ◽  
1997 ◽  
Vol 26 (1_suppl) ◽  
pp. 59-59
Author(s):  
J M Zanker ◽  
M P Davey
Keyword(s):  
Visual Field ◽  
Visual System ◽  
Computer Simulations ◽  
Visual Information ◽  
Human Performance ◽  
Receptive Fields ◽  
Experimental Result ◽  
Orientation Tuning ◽  
Basic Question ◽  
Visual Stream

Visual information processing in primate cortex is based on a highly ordered representation of the surrounding world. In addition to the retinotopic mapping of the visual field, systematic variations of the orientation tuning of neurons are described electrophysiologically for the first stages of the visual stream. On the way to understanding the relation of position and orientation representation, in order to give an adequate account of cortical architecture, it will be an essential step to define the minimum spatial requirements for detection of orientation. We addressed the basic question of spatial limits for detecting orientation by comparing computer simulations of simple orientation filters with psychophysical experiments in which the orientation of small lines had to be detected at various positions in the visual field. At sufficiently high contrast levels, the minimum physical length of a line whose orientation can just be resolved is not constant when presented at various eccentricities, but covaries inversely with the cortical magnification factor. A line needs to span less than 0.2 mm on the cortical surface in order to be recognised as oriented, independently of the actual eccentricity at which the stimulus is presented. This seems to indicate that human performance for this task approaches the physical limits, requiring hardly more than approximately three input elements to be activated, in order to detect the orientation of a highly visible line segment. Combined with the estimates for receptive field sizes of orientation-selective filters derived from computer simulations, this experimental result may nourish speculations of how the rather local elementary process underlying orientation detection in the human visual system can be assembled to form much larger receptive fields of the orientation-sensitive neurons known to exist in the primate visual system.

A Virtual Reality Approach for Minimizing Information Loss in Multi-User, Scalable Environments

2015 ◽  
Author(s):  
Bryan Dickens ◽  
Steven Sellers ◽  
Gabe Harms ◽  
Owen Shartle ◽  
Conrad S. Tucker
Keyword(s):  
Virtual Reality ◽  
Real Time ◽  
Information Exchange ◽  
Visual Information ◽  
Information Dissemination ◽  
Research Question ◽  
Information Loss ◽  
Sound Waves ◽  
Brick And Mortar

The authors of this work propose a virtual reality approach that overcomes two fundamental challenges experienced in physical learning environments; i) variations in audial quality, and ii) variations in visual quality, in an effort to achieve individual customization of information content. In physical brick and mortar environments, the dissemination of information is influenced by the medium that the information travels through, which is typically distorted by line of sight constraints and constraints that distort sound waves. The fundamental research question is how to achieve consistent quality of information being disseminated, as the number of audience members increases? There exists a knowledge gap relating to the creation of a scalable, networked, system for enabling real time, information exchange. The authors propose a virtual reality approach to address these limitations of physical learning spaces that minimizes the variability in audial and visual information dissemination. A real time, networked architecture is proposed that enables multiple individuals to simultaneously experience the same quality of audial and visual information, based on the optimal geospatial position for audial and visual exposure determined. A case study is introduced that first quantifies simulations of the audial and visual information loss experienced by audience members receiving information at different geospatial locations in a brick and mortar environment. This information loss is compared against the proposed virtual reality architecture that minimizes the variation in information dissemination. The authors demonstrate that the proposed solution is an improved, scalable multi-user system, unlike brick and mortar environments that are constrained by size and geospatial positioning.

The echolocation calls of hoary (Lasiurus cinereus) and silver-haired (Lasionycteris noctivagans) bats as adaptations for long- versus short-range foraging strategies and the consequences for prey selection

1986 ◽  
Vol 64 (12) ◽  
pp. 2700-2705 ◽  
Author(s):  
Robert M. R. Barclay
Keyword(s):  
Prey Selection ◽  
Foraging Strategy ◽  
Prey Detection ◽  
Constant Frequency ◽  
Insectivorous Bats ◽  
Lasiurus Cinereus ◽  
Echolocation Calls ◽  
Close Range ◽  
Search Approach ◽  
Lasionycteris Noctivagans

Amongst aerial-feeding insectivorous bats, differences in the design of echolocation calls appear to be associated with differences in foraging strategy. Recordings and observations of hoary (Lasiurus cinereus) and silver-haired (Lasionycteris noctivagans) bats in Manitoba, Canada, support such an association. Lasionycteris noctivagans use multiharmonic search–approach calls with an initial frequency sweep and a constant frequency tail. Such calls are suited for bats foraging in the open but near obstacles, and pursuing prey detected at relatively close range. This is the foraging strategy employed by this relatively slow, manoeuverable species. Lasiurus cinereus employ single harmonic search–approach calls that are low (20–17 kHz), essentially constant frequency signals. Calls of this design are suited for long-range target detection in open air situations, the foraging strategy used by L. cinereus. Differences in call design may explain dietary differences between the two species. Lasiurus cinereus consistently prey on large insects. The low, constant frequency design of their calls means that small insects are detectable only at close range and are thus difficult for this fast-dying bat to catch. The broad-band calls used by L. noctivagans do not restrict prey detection and these bats prey on a wider range of insects. Similar restrictions on prey detection, caused by echolocation call specializations, may be important in producing what might otherwise be considered active prey selection by some insectivorous bats.

Visual Information in Judgments of Head-On Collisions

2007 ◽  
Vol 51 (24) ◽  
pp. 1555-1559
Author(s):  
Kerstan S. Mork ◽  
Patricia R. DeLucia
Keyword(s):  
Optical Flow ◽  
Flow Pattern ◽  
Computer Simulations ◽  
Visual Information ◽  
Flow Information ◽  
Self Motion

Head-on collisions result in a substantial number of fatalities. To detect head-on collisions, drivers must judge effectively the direction or heading of their own vehicle in relation to the heading of oncoming vehicles. In our previous study, we used computer simulations of self-motion through a traffic scene to measure judgments about whether a head-on collision was imminent. Results suggested that judgments about head-on collision are affected by both the optical flow information provided by the centerline and the optical flow information provided by the oncoming car. The objective of the current study was to further examine the effect of different components of the optical flow pattern on judgments of head-on collisions. We measured judgments about head on collisions while manipulating local optical flow from the oncoming car and global optical flow from the background scenery. Our results suggest that visual information about the oncoming car's motion was more effective than visual information about self motion. The implication is that it may be beneficial for drivers to focus greater attention on the information about the oncoming car's motion in order to improve judgments about head-on collisions. Further research is needed to evaluate this possibility.

Ultrasonography

2019 ◽  
pp. 808-815
Author(s):  
Santiago Naranjo-Sierra ◽  
Lauren K. Ng Tucker
Keyword(s):  
Intensive Care Unit ◽  
Emergency Medicine ◽  
Visual Information ◽  
Point Of Care ◽  
Clinical Status ◽  
Standard Of Care ◽  
Sound Waves ◽  
Current Standard ◽  
Point Of Care Ultrasonography ◽  
Management Changes

Ultrasonography is the use of sound waves to create images and is used mainly for diagnostic purposes and for real-time guidance during procedures. Point-of-care ultrasonography is widely used in fields such as anesthesia, critical care, and emergency medicine, in which it is becoming an important part of the current standard of care because of its ability to provide accurate visual information about a patient, either to rapidly evaluate clinical status or to provide guidance for procedures, without requiring transfers to other areas. For patients in an intensive care unit, focused ultrasonography has been reported to result in management changes in more than 50%.

Variation in the echolocation calls of the hoary bat (Lasiurus cinereus): influence of body size, habitat structure, and geographic location

1999 ◽  
Vol 77 (4) ◽  
pp. 530-534 ◽  
Author(s):  
Robert MR Barclay ◽  
James H Fullard ◽  
David S Jacobs
Keyword(s):  
Visual Information ◽  
Habitat Type ◽  
Geographic Location ◽  
Encounter Rate ◽  
Echolocation Call ◽  
Lasiurus Cinereus ◽  
Echolocation Calls ◽  
Hoary Bat ◽  
The Individual ◽  
Rule Out

The echolocation calls of bats vary according to the task being undertaken by the individual. Within species, there is evidence for geographic, habitat, and individual variation, although it is often difficult to separate these factors and rule out variation in recording or analysis techniques. We studied the variation in echolocation call design of the hoary bat (Lasiurus cinereus) by analyzing calls, recorded in the same manner, from free-flying bats at one site in Manitoba and at four sites in the Hawaiian islands. Sites varied in terms of the proximity of the bats to vegetation. As predicted, individuals from the larger subspecies (Lasiurus cinereus cinereus; Manitoba) used lower frequency calls than did the smaller individuals in Hawaii. Within the same habitat type (open or closed), there was evidence for differences in echolocation call design between populations on different islands. On the island of Hawaii, bats at a single site used shorter higher frequency calls when foraging within the vegetation than when foraging in the open, again as predicted. However, bats foraging in different sites used calls with the opposite characteristics to those predicted on the basis of the openness of the site. Although there are several possible explanations for this, we suggest that prey encounter rate and the ability of bats to augment acoustic prey detection with visual information may be important.

scholarly journals Activation of the hypothalamic feeding centre upon visual prey detection

2017 ◽  
Author(s):  
Akira Muto ◽  
Pradeep Lal ◽  
Deepak Ailani ◽  
Gembu Abe ◽  
Mari Itoh ◽  
...  
Keyword(s):  
Visual Information ◽  
Prey Capture ◽  
Prey Detection ◽  
Hypothalamic Area ◽  
Zebrafish Larvae ◽  
Prey Recognition ◽  
Food Detection ◽  
Feeding Motivation ◽  
Freely Behaving ◽  
Pretectal Area

The visual system plays a major role in food/prey recognition in diurnal animals, and food intake is regulated by the hypothalamus. However, whether and how visual information about prey is conveyed to the hypothalamic feeding centre is largely unknown. Here we perform real-time imaging of neuronal activity in freely behaving or constrained zebrafish larvae and demonstrate that prey or prey-like visual stimuli activate the hypothalamic feeding centre. Furthermore, we identify prey detector neurons in the pretectal area that project to the hypothalamic feeding centre. Ablation of the pretectum completely abolishes prey capture behaviour and neurotoxin expression in the hypothalamic area also reduces feeding. Taken together, these results suggest that the pretecto-hypothalamic pathway plays a crucial role in conveying visual information to the feeding centre. Thus, this pathway possibly converts visual food detection into feeding motivation in zebrafish.

scholarly journals A Psychophysiological Study of Auditory Illusions of Approach and Withdrawal in the Context of the Perceptual Environment

2007 ◽  
Vol 10 (2) ◽  
pp. 266-276 ◽  
Author(s):  
Inna A. Vartanyan ◽  
Irina G. Andreeva
Keyword(s):  
Visual Information ◽  
Movement Direction ◽  
Sound Waves ◽  
Sound Sources ◽  
Auditory Image ◽  
Psychophysiological Study ◽  
Movement Assessment ◽  
Frequency Changes ◽  
Signal Tone ◽  
Approach And Withdrawal

Auditory perception of the depth of space is based mainly on spectral and amplitude changes of sound waves originating from the sound source and reaching the listener. The perceptive illusion of movement of an auditory image caused by changes in amplitude and/or frequency of the signal tone emanating from an immobile loudspeaker was studied. Analysis of data obtained from the participants revealed the diapason of combinations of amplitude and frequency changes for which the movement direction was perceived similarly by all participants, despite significantly different movement assessment criteria. Additional auditory and visual information of the conditions of radial movement (near or far fields) determined listeners' interpretation of changes in the signal parameters. The data obtained about the perception of approach and withdrawal models are evidence of the fact that the principal cues of the perception of the distance of immobile sound sources manifests similarly to that of an auditory image moving along a radial axis.

A High Resolution Study of G.P. Zones in Aluminum - 4.2 at % Silver

1982 ◽  
Vol 40 ◽  
pp. 722-723 ◽  
Author(s):  
R. Gronsky
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Resolution ◽  
Computer Simulations ◽  
Structural Characteristics ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Resolution Study

The phenomenon of clustering in Al-Ag alloys has been extensively studied since the early work of Guinierl, wherein the pre-precipitation state was characterized as an assembly of spherical, ordered, silver-rich G.P. zones. Subsequent x-ray and TEM investigations yielded results in general agreement with this model. However, serious discrepancies were later revealed by the detailed x-ray diffraction - based computer simulations of Gragg and Cohen, i.e., the silver-rich clusters were instead octahedral in shape and fully disordered, atleast below 170°C. The object of the present investigation is to examine directly the structural characteristics of G.P. zones in Al-Ag by high resolution transmission electron microscopy.

Multislice calculations for quasi-periodic and non-periodic objects

1990 ◽  
Vol 48 (4) ◽  
pp. 138-139
Author(s):  
R. Herrera ◽  
A. Gómez
Keyword(s):  
Electron Diffraction ◽  
Computer Simulations ◽  
Periodic Table ◽  
Amorphous Materials ◽  
Space Group ◽  
Essential Step ◽  
Shape Effects ◽  
Atomic Scattering ◽  
Diffraction Patterns ◽  
Periodic Continuation

Computer simulations of electron diffraction patterns and images are an essential step in the process of structure and/or defect elucidation. So far most programs are designed to deal specifically with crystals, requiring frequently the space group as imput parameter. In such programs the deviations from perfect periodicity are dealt with by means of “periodic continuation”.However, for many applications involving amorphous materials, quasiperiodic materials or simply crystals with defects (including finite shape effects) it is convenient to have an algorithm capable of handling non-periodicity. Our program “HeGo” is an implementation of the well known multislice equations in which no periodicity assumption is made whatsoever. The salient features of our implementation are: 1) We made Gaussian fits to the atomic scattering factors for electrons covering the whole periodic table and the ranges [0-2]Å−1 and [2-6]Å−1.

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