Some Dimensions of the Angular Acceleration Receptor Systems of Cephalopods

1984 ◽  
Vol 64 (1) ◽  
pp. 55-79 ◽  
Author(s):  
Linda Maddock ◽  
J. Z. Young
Keyword(s):  
Angular Velocity ◽  
Frequency Band ◽  
Deep Sea ◽  
Horizontal Plane ◽  
Angular Acceleration ◽  
The Body ◽  
The Other ◽  
Radius Of Curvature ◽  
Internal Radius ◽  
Neutrally Buoyant

The shapes and dimensions of the statocysts of cephalopods have been measured and compared with the semi-circular canals of vertebrates. The cavities grow much more slowly than the body as a whole, but there are knobs, anticristae, which restrict the cavity, and these grow relatively faster. This ensures that the flow of endolymph across the cupulae remains small. Where the liquid is constrained within canals the radius of curvature of the whole canal, R, is similar to that of fishes, whereas its internal radius, r, is twice as large in non-buoyant and four times as large in deep-sea buoyant cephalopods as in fishes of similar size. As in fishes the restriction is greatest in the horizontal plane, providing for operation at higher frequencies in turning about the yaw axis.The statocysts of seven species of Loligo all have similar proportions. The largest individuals of 16 genera of non-buoyant squids also have these same relative dimensions. The statocyst of Sepia is more like that of non-buoyant than of other buoyant cephalopods but yet differs significantly from that of Loligo at all sizes. On the other hand 21 genera of squids known to be neutrally buoyant are very different. Their statocysts are often larger than in the non-buoyant forms and there is less restriction of the cavity by anticristae. The greater flow of endolymph acting across the cupulae presumably provides greater sensitivity at the lower frequencies of turning of these deep-sea animals.The data suggest that the cristae of the cephalopod statocyst may operate in the frequency band where they act as angular accelerometers whereas the vertebrate semi-circular canals operate at higher frequencies as angular velocity meters.

Computation of Rigid-Body Angular Acceleration From Point-Acceleration Measurements

1987 ◽  
Vol 109 (2) ◽  
pp. 124-127 ◽  
Author(s):  
Jorge Angeles
Keyword(s):  
Angular Velocity ◽  
Rigid Body ◽  
Measurement Errors ◽  
Angular Acceleration ◽  
The Body ◽  
The Other ◽  
Compatibility Conditions ◽  
Other Hand ◽  
The One

The computation of the angular acceleration of a rigid body from measurements of accelerations of three noncollinear points of the body is presented in this paper. This is based on algorithms presented previously for the computation of the orientation and the angular velocity of a rigid body from measurements of position and velocity of three noncollinear points of the body. Moreover, compatibility conditions that the said point measurements should verify are introduced. These are necessary to verify the rigidity assumption on the one hand; on the other hand, they are introduced as a means of filtering roundoff and/or measurement errors, which is particularly useful if redundant measurements are taken, i.e., on more than three points. The procedure is illustrated with a fully solved example.

Kinematics of rotation in place during defense turning in the crayfish Procambarus clarkii

2001 ◽  
Vol 204 (3) ◽  
pp. 471-486 ◽  
Author(s):  
N. Copp ◽  
M. Jamon
Keyword(s):  
Angular Velocity ◽  
Procambarus Clarkii ◽  
Angular Acceleration ◽  
The Body ◽  
Simple Variation ◽  
Freely Behaving ◽  
Leg Motion ◽  
Two Phases ◽  
Analysis System ◽  
Final Orientation

The kinematic patterns of defense turning behavior in freely behaving specimens of the crayfish Procambarus clarkii were investigated with the aid of a video-analysis system. Movements of the body and all pereiopods, except the chelipeds, were analyzed. Because this behavior approximates to a rotation in place, this analysis extends previous studies on straight and curve walking in crustaceans. Specimens of P. clarkii responded to a tactile stimulus on a walking leg by turning accurately to face the source of the stimulation. Angular velocity profiles of the movement of the animal's carapace suggest that defense turn responses are executed in two phases: an initial stereotyped phase, in which the body twists on its legs and undergoes a rapid angular acceleration, followed by a more erratic phase of generally decreasing angular velocity that leads to the final orientation. Comparisons of contralateral members of each pair of legs reveal that defense turns are affected by changes in step geometry, rather than by changes in the timing parameters of leg motion, although inner legs 3 and 4 tend to take more steps than their outer counterparts during the course of a response. During the initial phase, outer legs 3 and 4 exhibit larger stance amplitudes than their inner partners, and all the outer legs produce larger stance amplitudes than their inner counterparts during the second stage of the response. Also, the net vectors of the initial stances, particularly, are angled with respect to the body, with the power strokes of the inner legs produced during promotion and those of the outer legs produced during remotion. Unlike straight and curve walking in the crayfish, there is no discernible pattern of contralateral leg coordination during defense turns. Similarities and differences between defense turns and curve walking are discussed. It is apparent that rotation in place, as in defense turns, is not a simple variation on straight or curve walking but a distinct locomotor pattern.

On the use of ammonium for buoyancy in squids

1979 ◽  
Vol 59 (2) ◽  
pp. 259-276 ◽  
Author(s):  
M. R. Clarke ◽  
E. J. Denton ◽  
J. B. Gilpin-Brown
Keyword(s):  
Developmental Stage ◽  
Sea Water ◽  
The Body ◽  
The Other ◽  
Neutral Buoyancy ◽  
Rich Solution ◽  
Almost All ◽  
Neutrally Buoyant

Squids (teuthoids) fall into two distinct groups according to their density in sea water. Squids of one group are considerably denser than sea water and must swim to stop sinking; squids in the other group are nearly neutrally buoyant. Analyses show that in almost all the neutrally buoyant squids large amounts of ammonium are present. This ammonium is not uniformly distributed throughout the body but is mostly confined to special tissues where its concentration can approach half molar. The locations of such tissues differ according to the species and developmental stage of the squid. It is clear that the ammonium-rich solution are almost isosmotic with sea water but of lower density and they are present in sufficient volume to provide the main buoyancy mechanism of these squids. A variety of evidence is given which suggests that squids in no less than 12 of the 26 families achieve near-neutral buoyancy in this way and that 14 families contain squids appreciably denser than sea water [at least one family contains both types of squid]. Some of the ammonium-rich squids are extremely abundant in the oceans.

scholarly journals On the Geodetic Rotation of the Major Planets, the Moon and the Sun

2009 ◽  
Vol 44 (2) ◽  
pp. 43-52
Author(s):  
G. Eroshkin ◽  
V. Pashkevich
Keyword(s):  
Angular Velocity ◽  
Reference Frame ◽  
Velocity Vector ◽  
Previous Investigation ◽  
The Body ◽  
The Other ◽  
The Sun ◽  
The Moon ◽  
Angular Velocity Vector

On the Geodetic Rotation of the Major Planets, the Moon and the SunThe problem of the geodetic (relativistic) rotation of the major planets, the Moon and the Sun was studied in the paper by Eroshkin and Pashkevich (2007) only for the components of the angular velocity vectors of the geodetic rotation, which are orthogonal to the plane of the fixed ecliptic J2000. This research represents an extension of the previous investigation to all the other components of the angular velocity vector of the geodetic rotation, with respect to the body-centric reference frame from Seidelmann et al. (2005).

RUSSIAN VESTIBULAR INVESTIGATIONS WITH PRIMATES IN FLIGHTS OF THE BIOSATELLITES

2020 ◽  
Vol 54 (6) ◽  
pp. 110-116
Author(s):  
I.B. Kozlovskaya ◽  
◽  
B.A. Lapin ◽  
N.V. Miller ◽  
A.M. Badakva ◽  
...  
Keyword(s):  
Cardiac Rhythm ◽  
Horizontal Plane ◽  
Vestibular Nuclei ◽  
Linear Displacement ◽  
The Body ◽  
Head Movements ◽  
Body Axis ◽  
The Other ◽  
Gaze Fixation ◽  
Vestibular Neurons

The BION program with primates included 2 vestibular studies one was focused on coordination of the eye and head movements and activities of the medial vestibular nuclei and cerebellum flocculus during angular head movements in the horizontal plane for gaze fixation and the other, on the central vestibular neurons and otolith-induced cardiac rhythm reaction during linear displacement about the body axis. Sensitivity of the central vestibular neurons to both angular and linear accelerations was found to increase at the beginning of microgravity and then normalized gradually, whereas the flocculus activity remained high throughout the mission.

scholarly journals Oxygen – the forgotten nutrient

2017 ◽  
Vol 6 ◽  
Author(s):  
Paul Trayhurn
Keyword(s):  
Deep Sea ◽  
Lung Diseases ◽  
Molecular Level ◽  
Hypoxia Inducible Factor ◽  
The Body ◽  
The Other ◽  
Anaerobic Glycolysis ◽  
Hypoxia Inducible Factor 1 ◽  
Nutritional Science ◽  
Relative Deficiency

AbstractO2 is essential for the maintenance and growth of aerobic animals, similar to the essentiality of what are classically considered nutrients. Nevertheless, O2 is not customarily regarded as a nutrient, this reflecting the route by which it enters the body – through the lungs or gills in vertebrates, rather than via the mouth and gastrointestinal tract. A relative deficiency of O2 occurs at high altitudes and during deep-sea diving, to which distinct adaptations occur. Deficiency is also evident in lung diseases such as emphysema. Without O2, mitochondrial respiration and oxidative phosphorylation cannot take place. At a molecular level, cells adapt to O2 deficiency by switching from oxidative metabolism to anaerobic glycolysis and there are changes in the expression of a multiplicity of genes, driven by hypoxia-sensitive transcription factors, particularly hypoxia-inducible factor-1. It is argued that O2 should be fully included within the remit of nutritional science alongside the other essential macronutrients.

Minimal Spatial Accelerometer Configurations

2013 ◽  
Vol 135 (2) ◽  
Author(s):  
Thomas R. Williams ◽  
Donald W. Raboud ◽  
Ken R. Fyfe
Keyword(s):  
Angular Velocity ◽  
Special Class ◽  
Design Methodology ◽  
Angular Acceleration ◽  
The Body ◽  
Specific Force ◽  
Geometric Conditions ◽  
Minimum Number ◽  
First Time ◽  
General Motion

It is well established that it is necessary to use a minimum of six accelerometers to determine the general motion of a rigid body. Using this minimum number of accelerometers generally requires that a nonlinear differential equation be solved for the angular velocity and that the estimate of angular velocity that is obtained from the solution of this equation be used in the calculation of the specific force at a point. This paper serves two main purposes. First it discusses, for the first time, the geometric conditions that must be satisfied by an arrangement of six accelerometers so that it is possible, in principle, to determine the motion of the body to which they are attached. Second, a special class of minimal accelerometer configurations that yields angular acceleration as a linear combination of accelerometer measurements is identified, and a design methodology for this special class is presented.

scholarly journals The Mechanics of the Growing Semicircular Canal

1973 ◽  
Vol 58 (2) ◽  
pp. 351-366
Author(s):  
J. H. TEN KATE
Keyword(s):  
Angular Velocity ◽  
Body Length ◽  
Semicircular Canal ◽  
Angular Acceleration ◽  
Radius Of Curvature ◽  
Sensitivity Factor ◽  
Growth Effects ◽  
Ocular Reflex ◽  
Vestibulo Ocular Reflex ◽  
Factor G

1. The motion of the endolymph in the semicircular canal is described with the aid of a linear second-order system, comprising the applied angular acceleration and the linear displacement, the linear velocity and the linear acceleration of the endolymph. 2. A sensitivity factor G for angular velocity is derived and expressed in the dimensions of the semicircular canal. 3. The sensitivity factor G of the semicircular canal proves to be consistent with the equivalent sensitivity factor of a more sophisticated hydrodynamic model of these canals. 4. The sensitivity of the growing semicircular canal is defined to be G/hc2, independent of the pike's size. Threshold angular velocities for the vestibulo-ocular reflex of 27 pike between 4 and 50 cm bodylength are in agreement with this assumption. 5. At threshold stimulation with an angular velocity of 2°/sec the radius of curvature Rc of the cupula is calculated to be 220±48 cm. 6. At the threshold angular velocity γ = 2°/sec the deviation of sensory hairs 5 µm long is assessed to be between 0.06 Å and 1 Å. 7. Young's modulus of elasticity for the cupular substance is found to be between 0.35 x 103 dyne/cm2 and 1.85 x 103 dyne/cm2 (on the basis of a circular bending for the cupula). 8. Characteristics of the model of the growing semicircular canal are calculated for pike with body length between 5 and 100 cm. 9. Observed growth effects of the pike's vestibulo-ocular reflex arc are correlated to the growth effects calculated on basis of the model for the growing semicircular canal. 10. The pike possesses the same degree of vestibulo-ocular compensation in the high-frequency range (2 radians/sec ≤ ω < 7 radians/sec) of angular oscillations during its whole life (11 observations of pike of body length 4-56 cm).

Conics and a generalised conical pendulum

2019 ◽  
Vol 103 (556) ◽  
pp. 28-40
Author(s):  
Daniel Daners ◽  
Theresa Wigmore
Keyword(s):  
Angular Velocity ◽  
Horizontal Plane ◽  
Circular Motion ◽  
The Other

There is a long tradition of using geometry to solve problems from mechanics. Unfortunately this tradition is not practised much in schools and university any more.With this exposition we would like to demonstrate how elementary properties of ellipses can be used to solve a problem related to the conical pendulum. The problem of the conical pendulum is to consider a mass attached to one end of a light inextensible string of length with the other end attached at the top of a vertical rod. The mass is moving about the rod in uniform circular motion in a horizontal plane. Given the angular velocity of the mass, the question is to determine the angle the string makes with the rod.

A Study on Mixed Kinetic-Kinematic Equations for Multibody Systems

2013 ◽  
Author(s):  
Sung-Soo Kim ◽  
Bongcheol Seo ◽  
Myungho Kim
Keyword(s):  
Angular Velocity ◽  
Velocity Vector ◽  
Reference Frames ◽  
Time Derivative ◽  
Kinetic Equations ◽  
Angular Acceleration ◽  
The Body ◽  
Integration Step ◽  
Angular Velocity Vector ◽  
The Relationship

In this paper, mixed kinetic-kinematic equations for a multibody system have been studied in order to resolve the difficulties of non-integrability of angular velocity vectors. As for the kinetic equations, the Newton-Euler equations of motion are considered. They are derived in terms of angular velocity and angular acceleration vectors expressed in the body fixed reference frames. As for the kinematic compatibility equations, two different equations are considered. One is from the relationship between the angular velocity vector and the time derivatives of Euler parameters. The other is from the relationship between the rotational orientation matrix, its time derivative, and the angular velocity vector. In order to investigate the accuracy of the solution methods using two different kinematic compatibility equations, simulations of a spherical pendulum model and a 1/6 robot vehicle model have been carried out. With different integration step-sizes, the constraint violation errors have been also investigated.

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