scholarly journals Air motion sensing hairs of arthropods detect high frequencies at near-maximal mechanical efficiency

2011 ◽  
Vol 9 (71) ◽  
pp. 1131-1143 ◽  
Author(s):  
Brice Bathellier ◽  
Thomas Steinmann ◽  
Friedrich G. Barth ◽  
Jérôme Casas
Keyword(s):  
Angular Displacement ◽  
Biological Significance ◽  
Mechanical Efficiency ◽  
Motion Sensing ◽  
High Frequencies ◽  
Spectral Signatures ◽  
Physical Limit ◽  
Image Velocimetry ◽  
Basal Articulation ◽  
Air Motion

Using measurements based on particle image velocimetry in combination with a novel compact theoretical framework to describe hair mechanics, we found that spider and cricket air motion sensing hairs work close to the physical limit of sensitivity and energy transmission in a broad range of relatively high frequencies. In this range, the hairs closely follow the motion of the incoming flow because a minimum of energy is dissipated by forces acting in their basal articulation. This frequency band is located beyond the frequency at which the angular displacement of the hair is maximum which is between about 40 and 600 Hz, depending on hair length (Barth et al . [ 1 ] Phil. Trans. R. Soc. Lond. B 340 , 445–461 ( doi:10.1098/rstb.1993.0084 )). Given that the magnitude of natural airborne signals is known to decrease with frequency, our results point towards the possible existence of spectral signatures in the higher frequency range that may be weak but of biological significance.

scholarly journals The aerodynamic cost of flight in the short-tailed fruit bat ( Carollia perspicillata ): comparing theory with measurement

2014 ◽  
Vol 11 (95) ◽  
pp. 20140147 ◽  
Author(s):  
Rhea von Busse ◽  
Rye M. Waldman ◽  
Sharon M. Swartz ◽  
Christian C. Voigt ◽  
Kenneth S. Breuer
Keyword(s):  
Interpolation Method ◽  
Laser Sheet ◽  
Power Input ◽  
Mechanical Efficiency ◽  
Flight Speed ◽  
Fruit Bat ◽  
Image Velocimetry ◽  
Theoretical Predictions ◽  
Stereo Particle Image Velocimetry ◽  
Animal Flight

Aerodynamic theory has long been used to predict the power required for animal flight, but widely used models contain many simplifications. It has been difficult to ascertain how closely biological reality matches model predictions, largely because of the technical challenges of accurately measuring the power expended when an animal flies. We designed a study to measure flight speed-dependent aerodynamic power directly from the kinetic energy contained in the wake of bats flying in a wind tunnel. We compared these measurements with two theoretical predictions that have been used for several decades in diverse fields of vertebrate biology and to metabolic measurements from a previous study using the same individuals. A high-accuracy displaced laser sheet stereo particle image velocimetry experimental design measured the wake velocities in the Trefftz plane behind four bats flying over a range of speeds (3–7 m s −1 ). We computed the aerodynamic power contained in the wake using a novel interpolation method and compared these results with the power predicted by Pennycuick's and Rayner's models. The measured aerodynamic power falls between the two theoretical predictions, demonstrating that the models effectively predict the appropriate range of flight power, but the models do not accurately predict minimum power or maximum range speeds. Mechanical efficiency—the ratio of aerodynamic power output to metabolic power input—varied from 5.9% to 9.8% for the same individuals, changing with flight speed.

A reexamination of the gain of the vestibuloocular reflex

1986 ◽  
Vol 56 (2) ◽  
pp. 439-450 ◽  
Author(s):  
E. Viirre ◽  
D. Tweed ◽  
K. Milner ◽  
T. Vilis
Keyword(s):  
Target Location ◽  
No Reduction ◽  
Angular Displacement ◽  
Head Rotation ◽  
Phase Lag ◽  
Vestibuloocular Reflex ◽  
High Frequencies ◽  
Axis Of Rotation ◽  
Large Gain ◽  
The Ideal

The properties of the vestibuloocular reflex (VOR) when the axis of rotation is behind the eyes and fixation of a near target is required were studied in the monkey. The magnitude of VOR gain in each eye was found to be above 1.0 and near the ideal value for stabilizing a retinal image. Evidence that this large VOR gain was not visually mediated was provided by the observations that no reduction in gain and no phase lag were observed at high frequencies of head rotation (2 Hz), large gain was observed in the dark, and large gain was observed within 10-20 ms of the start of head rotation. The magnitude of VOR gain was found to increase with increasing radius of head rotation and also to increase with decreasing target distance. When the distances from the two eyes to the target were different the instantaneous velocities and VOR gains of the eyes were also different. The dependence on radius of rotation indicates that the VOR is mediated by a combination of otolith and canal inputs. A general model for otolith-canal interaction is proposed in which VOR gain is based on a computation of target location relative to the head. This model simplifies to the classical VOR reflex when a cyclopean eye is subjected only to angular displacement.

scholarly journals Ontogeny of air-motion sensing in cricket

2006 ◽  
Vol 209 (21) ◽  
pp. 4363-4370 ◽  
Author(s):  
O. Dangles ◽  
D. Pierre ◽  
C. Magal ◽  
F. Vannier ◽  
J. Casas
Keyword(s):  
Motion Sensing ◽  
Air Motion

scholarly journals Probing vortex-shedding at high frequencies in flows past confined microfluidic cylinders using high-speed microscale particle image velocimetry

2019 ◽  
Vol 31 (10) ◽  
pp. 102001 ◽  
Author(s):  
Shigang Zhang ◽  
Neil Cagney ◽  
Stavroula Balabani ◽  
Carolina P. Naveira-Cotta ◽  
Manish K. Tiwari
Keyword(s):  
Particle Image Velocimetry ◽  
Vortex Shedding ◽  
High Speed ◽  
Particle Image ◽  
High Frequencies ◽  
Image Velocimetry

scholarly journals Response of cricket and spider motion-sensing hairs to airflow pulsations

2009 ◽  
Vol 6 (40) ◽  
pp. 1047-1064 ◽  
Author(s):  
R. Kant ◽  
J. A. C. Humphrey
Keyword(s):  
Energy Content ◽  
Angular Displacement ◽  
Gaussian Function ◽  
Flow Pulsation ◽  
Motion Sensing ◽  
Time Duration ◽  
Velocity Signal ◽  
Lower Velocity ◽  
Cupiennius Salei ◽  
Behavioural Experiments

Closed-form analytical solutions are presented for the angular displacement, velocity and acceleration of motion-sensing filiform hairs exposed to airflow pulsations of short time duration. The specific situations of interest correspond to a spider intentionally moving towards a cricket, or an insect unintentionally moving towards or flying past a spider. The trichobothria of the spider Cupiennius salei and the cercal hairs of the cricket Gryllus bimaculatus are explored. Guided by earlier work, the spatial characteristics of the velocity field due to a flow pulsation are approximated by the local incompressible flow field due to a moving sphere. This spatial field is everywhere modulated in time by a Gaussian function represented by the summation of an infinite Fourier series, thus allowing an exploration of the spectral dependence of hair motion. Owing to their smaller total inertia, torsional restoring constant and total damping constant, short hairs are found to be significantly more responsive than long hairs to a flow pulsation. It is also found that the spider trichobothria are underdamped, while the cercal hairs of the cricket are overdamped. As a consequence, the spider hairs are more responsive to sudden air motions. Analysis shows that while two spiders of different characteristic sizes and lunge velocities can generate pulsations with comparable energy content, the associated velocity fields display different patterns of spatial decay with distance from the pulsation source. As a consequence, a small spider lunging at a high velocity generates a smaller telltale far-field velocity signal than a larger spider lunging at a lower velocity. The results obtained are in broad agreement with several of the observations and conclusions derived from combined flow and behavioural experiments performed by Casas et al . for running spiders, and by Dangles et al . for spiders and a physical model of spiders lunging at crickets.

An Airborne Laser Air Motion Sensing System. Part I: Concept and Preliminary Experiment

1987 ◽  
Vol 4 (1) ◽  
pp. 113-127 ◽  
Author(s):  
R. J. Keeler ◽  
R. J. Serafin ◽  
R. L. Schwiesow ◽  
D. H. Lenschow ◽  
J. M. Vaughan ◽  
...  
Keyword(s):  
Motion Sensing ◽  
Sensing System ◽  
Airborne Laser ◽  
System Part ◽  
Air Motion

Quasi-Periodic Oscillations in Dwarf Novae

1979 ◽  
Vol 46 ◽  
pp. 77-88
Author(s):  
Edward L. Robinson
Keyword(s):  
Binary Systems ◽  
Outer Edge ◽  
Light Curves ◽  
Close Binary ◽  
Bright Spot ◽  
Dwarf Novae ◽  
Periodic Oscillations ◽  
High Frequencies ◽  
Short Period ◽  
Typical Time

Three distinct kinds of rapid variations have been detected in the light curves of dwarf novae: rapid flickering, short period coherent oscillations, and quasi-periodic oscillations. The rapid flickering is seen in the light curves of most, if not all, dwarf novae, and is especially apparent during minimum light between eruptions. The flickering has a typical time scale of a few minutes or less and a typical amplitude of about .1 mag. The flickering is completely random and unpredictable; the power spectrum of flickering shows only a slow decrease from low to high frequencies. The observations of U Gem by Warner and Nather (1971) showed conclusively that most of the flickering is produced by variations in the luminosity of the bright spot near the outer edge of the accretion disk around the white dwarf in these close binary systems.

Microstructural morphology of sphingolipid dispersions as investigated by freeze-fracture EM

1995 ◽  
Vol 53 ◽  
pp. 944-945
Author(s):  
Vitthal S. Kulkarni ◽  
Wayne H. Anderson ◽  
Rhoderick E. Brown
Keyword(s):  
Acyl Chain ◽  
Biological Significance ◽  
Freeze Fracture ◽  
Fatty Acyl ◽  
Fatty Acyl Moiety ◽  
Aqueous Dispersions ◽  
Head Groups ◽  
Lipid Species ◽  
Microstructural Morphology ◽  
Layer Chromatography

The biological significance of the sphingomyelins (SM) and monoglycosylated sphingolipids like galactosylceramides (GalCer) are well documented Our recent investigation showed tubular bilayers in the aqueous dispersions of N-nervonoyl GalCer [N-(24:lΔ15,cls) GalCer] (a major fatty acyl moiety of natural GalCer). To determine the influence of lipid head groups on the resulting mesophasic morphology, we investigated microstructural self-assemblies of N-nervonoyl-SM [N-(24:1 Δ15,cls) SM; the second most abundant sphingomyelin in mammalian cell membranes], 1- palmitoyl-2-nervonoyl phosphatidylcholine [PNPC] (the lipid species with the same acyl chain configuration as in N-(24: 1) GalCer) and also compared it with egg-SM by freeze-fracture EM.Procedures for synthesizing and purifying N-(24:1) GalCer, N-(24:1) SM, and PNPC have been reported . Egg-SM was purchased from Avanti Polar Lipids, Alabaster AL. All lipids were >99% pure as checked by thin layer chromatography. Lipid dispersions were prepared by hydrating dry lipid with phosphate buffer (pH 6.6) at 80-90°C (3-5 min), vigorously vortexing (1 min) and repeating this procedure for three times prior to three freeze-thaw cycles.

Sign in / Sign up

Export Citation Format

Share Document