Undulation Frequency Research Articles

Kinematics of Swimming Garter Snakes ( Thamnophis sirtalis)

We investigate the kinematics of swimming garter snakes ( Thamnophis sirtalis) using a novel nonlinear regression-based digitization method to establish quantitative statistical support for non-constant wavelengths in the undulatory pattern exhibited by swimming snakes. We find that in swimming snakes, the growth of the amplitude of the propulsive wave head-to-tail is strongly correlated ( p < 0.005) with the head-to-tail growth in the wavelength. We investigate correlations between kinematic parameters and steady swimming speed, and find a very strong positive correlation between swimming speed and undulation frequency. We furthermore find a statistically well-supported positive correlation between swimming speed and both the initial amplitude of the propulsive wave at the head and the degree of amplitude growth from head to tail.

Intensity tuning characteristics of double-mode He–Ne laser with optical feedback

This paper investigates the intensity tuning characteristics of a double longitudinal modes He–Ne laser subjected to optical feedback. The intensity undulations of the total light and the two modes are observed for different external cavity length. Two modulations of the internal cavity length are performed. One is only for the internal cavity length being modulated and the other is for both the internal and the external cavity length being modulated. The undulation frequency of the total light is found to be determined by the ratio of external cavity length to internal cavity length in both modulations. When the external cavity length is integral times of the internal cavity length, the fringe frequency of the total light could be seven or even more times of that in conventional optical feedback. A simple theoretical analysis is presented, which is in good agreement with the experimental results. The potential use of the experimental results is also discussed.

Conservation rules, their breakdown, and optimality in Caenorhabditis sinusoidal locomotion

Undulatory locomotion is common to nematodes as well as to limbless vertebrates, but its control is not understood in spite of the identification of hundred of genes involved in Caenorhabditis elegans locomotion. To reveal the mechanisms of nematode undulatory locomotion, we quantitatively analysed the movement of C. elegans with genetic perturbations to neurons, muscles, and skeleton (cuticle). We also compared locomotion of different Caenorhabditis species. We constructed a theoretical model that combines mechanics and biophysics, and that is constrained by the observations of propulsion and muscular velocities, as well as wavelength and amplitude of undulations. We find that normalized wavelength is a conserved quantity among wild-type C. elegans individuals, across mutants, and across different species. The velocity of forward propulsion scales linearly with the velocity of the muscular wave and the corresponding slope is also a conserved quantity and almost optimal; the exceptions are in some mutants affecting cuticle structure. In theoretical terms, the optimality of the slope is equivalent to the exact balance between muscular and visco-elastic body reaction bending moments. We find that the amplitude and frequency of undulations are inversely correlated and provide a theoretical explanation for this fact. These experimental results are valid both for young adults and for all larval stages of wild-type C. elegans. In particular, during development, the amplitude scales linearly with the wavelength, consistent with our theory. We also investigated the influence of substrate firmness on motion parameters, and found that it does not affect the above invariants. In general, our biomechanical model can explain the observed robustness of the mechanisms controlling nematode undulatory locomotion.

Effects of size and behavior on aerial performance of two species of flying snakes (Chrysopelea)

Aerial locomotion in snakes (genus Chrysopelea) is kinematically distinct from any other type of gliding or powered flight, with prominent, high amplitude body undulations visually dominating the behavior. Because it is not known how flying snakes produce aerodynamic forces in flight, the factors that determine snake flight performance are not clear. In this study, the effects of size and behavior on aerial performance were examined both within a species (C. paradisi) and between two species (C. paradisi and C. ornata), using stepwise multiple regressions to identify relevant variables. Smaller C. paradisi traveled farther than larger snakes at lower sinking speeds, with trajectories that shallowed more quickly and reached lower minimum glide angles. Although wing loading increased faster than expected for isometric size increase, wing loading per se was not responsible for performance differences between large and small snakes. Snakes with higher interactions between relative undulation amplitude and body size transitioned out of the initial acceleration phase at higher airspeeds and sinking speeds, and attained higher maximum airspeeds and horizontal speeds; snakes that used higher average relative amplitudes transitioned out of the initial acceleration phase at higher horizontal speeds. Undulation frequency was not significantly related to any performance variable within C. paradisi and was not significantly different between the two species, suggesting that this variable (in contrast to relative undulation amplitude) may have a minor influence on the aerodynamic mechanism of force production in snake flight. C. paradisi and C. ornata differed significantly in most performance comparisons. C. ornata were more massive than C. paradisi at any given body length and in general exhibited poorer gliding performance than C. paradisi. This study contributes towards understanding how an unconventional body form and kinematics can produce a novel mode of aerial locomotion in a vertebrate glider.

Influence de la distance de course sur les paramètres cinématiques de nage chez les nageurs avec palmes de haut niveau

Introduction – Finswimming is a new sport activity. The optimization of the leg’s propulsive action is fundamental to improve the performance. The aim of this work is to quantify finswimmer’s movements per race distances, using a kinematic analysis. Fact synthesis – Five elite finswimmers were video recorded during underwater races. The connections between the average velocity of stroke, frequency and range of finswimmers undulation are observed as a fonction of race distance. Conclusion – Finswimmers are shown to adjust and to stabilize instantaneously their movements in terms of race distance.

Determination of the quench velocity and rewetting temperature of hot surfaces. Part I: analytical solution of the micro-scale hydrodynamic model

The hydrodynamic micro-scale model, developed previously, is used to solve the non-isothermal interface equation. The complex interface equation is simplified in a coordinate frame that moves with the three-phase contact line. This equation accounts for effects of evaporation, thermo-capillary and intermolecular forces. The new non-isothermal interface equation provides generalization of de Gennes’ equation that applies to the isothermal case. The simplified third-order differential equation is solved numerically, and the effect of numerical parameters and selection of boundary conditions on solution convergence are established for a wide range of properties of solid–liquid pairs. In contrast to the smooth isothermal interfaces, non-isothermal interfaces are characterized by an undulating or wavy geometry. This behavior is a reflection of evaporation and mass transfer occurring across the interface, and unique capillary and thermocapillary effects that arise under non-isothermal conditions. A parametric study of the interface solution shows that increase of the capillary, C, and thermocapillary, Cθ 0 2/ F numbers produces steeper interface profiles, whereas the factor N, evaporation coefficient S, and the Hamaker constant Ā, produce the reverse effect. Larger values of N, S and Ā result in higher undulation frequencies. These effects intensify and become dominant under rewetting conditions. The new interface equation provides an advanced tool for further studies of hydrodynamic mechanisms that govern the motion of thin liquid films on hot solid surfaces, that involve high temperature gradients and intense evaporation. This furnishes a hydrodynamic foundation for analysis of rewetting phenomena, and the definition of rewetting temperature and quench velocity, that are presented in a subsequent paper.

Gated escaping of ligand out of protein

We construct a new gating model and develop a new theory to study the escaping process of a ligand out of a spherical cavity with a puncture (or gate) on the surface. The gate undulation can be regulated by any time-dependent function and the motion of the ligand inside the spherical cavity is mapped into a two-dimensional entropy potential surface. Hence the driving force of our model is entropy only. For a static gate, the escaping process corresponds to climbing a two-dimensional entropy barrier. When the gate open angle is small, the escaping rate is proportional to the square of the opening angle. The prefactor of the escaping rate constant depends on the curvature of the entropy potential surface. For coherent gating, the survival time depends not only on the gate undulation frequency but also on how the initial state is defined. On the escaping from protein, our escaping rate shows it is qualitatively consistent with the experimental result of ligand recombination in myoglobin.

Emotions in the singing voice: Acoustic cues for joy, fear, anger, and sadness

Singers can vocally express their emotional interpretation of a musical piece. The analysis of melodies performed by trained sopranos in four labeled affective states, revealed differences in time, amplitude, spectral, and frequency parameters. The tempo was 40% slower in samples expressing sadness, while other modifications of rhythm showed no emotion-specific patterns. Complex amplitude modulations within a tone were reduced to two parameters: the maximum amplitude and its position. In joy and anger, that maximum amplitude was higher and appeared earlier within a tone. Sound-pressure levels were significantly lower in fear and sadness. The energy distribution in the spectrum, which is reflecting timbre, did not show any differences in the lower harmonics, but the peak amplitude of the singer’s formant (clustering of third to fifth harmonic) was significantly higher in joy and anger. The extent of the vibrato, a characteristic feature for the voice of a trained singer, and the variations of the extent depended on the emotional expression. The linear average of the vibrato note’s undulating frequency as an approximation for the perceived pitch differed up to 5 to 10 Hz between emotions, with a tendency to lower frequencies in sadness.

An Atomic Force Microscopy Study on the Roughness of Silicon Wafers Correlated with Direct Wafer Bonding

Atomic force microscopy has been used to quantitatively determine the surface roughness of silicon substrates as a function of processing and limitations to direct wafer bonding ability. This data is conveniently converted into a power spectrum creating a description of the topography which contains information about the amplitude and frequency of the surface undulations. Following initial characterization, the wafers were subjected to typical device manufacturing processes resulting in various degrees of increased roughness. An empirical correlation was developed between the roughness spectrum and bondability of (100) silicon wafers. Data on the roughening of wafers due to various standard integrated circuit processing steps were obtained and used to identify processes which promote wafer‐to‐wafer direct bonding. The fractal dimensions of the surfaces have been calculated and are discussed.

Wave characteristics of butterfly swimming

In this study it was hypothesized that elite butterfly performance is characterized by wave motions with particular frequency, amplitude, and phase characteristics. Particular emphasis was accorded the question of whether ‘waves’ travel along the body during the butterfly stroke. Selected body landmarks and the center of mass (CM) of eight elite males and eight elite female swimmers were quantified. Fourier analysis was conducted to determine the frequency, amplitude, and phase characteristics of the vertical undulations of the vertex of the head, shoulders, hips, knees, and ankles. The differences in phase between these landmarks for the first (H1) and second (H2) Fourier frequencies were investigated to establish whether waves travelled along the body in a caudal direction. The absolute average velocity of H1 wave travel from vertex to ankle was found to be a mean of 0.34 m s −1 faster than the forward velocity of the CM for the male swimmers and 0.17 m s −1 faster for the female swimmers. There was a very strong relationship ( p<0.01) between velocity of H1 wave travel and CM velocity. There was no evidence to suggest that elite swimmers timed their actions to minimise vertical CM displacement to reduce mechanical work. In fact, the phase relationships among adjacent segments suggested that energy gained by raising the CM was transmitted caudally and contributed to a propulsive ‘whip-like’ action.

千葉県南部沿岸のアワビ稚貝場の地形並びに流況

The authors studied these factors of sea bottom type and its current which seemed to make nursery ground. In the bottom types, it was discovered that the frequency of rock undulations in the abalone habitat were 0.60 to 0.81 per meter, and the relation between surf course and rock lines was almost 90 degrees. The depth of abalone habitats was less than 7 meters mainly. And the bottom consists of rock or mixed with sandy zone. As regards the current factor, the current speed of 0.07 to 0.48 meter per second in Kawaguchi and Otohama nursery ground of abalone, was verified. Especially, we got slow current on the nursery ground which were 0.02 to 0.21 meter per second except one station. We anticipated the existence of some eddy zones by the figure of residual current, and eddy zones were made behind the nursery habitat.

Swimming in Constricting (Elaphe g. guttata) and Nonconstricting (Nerodia fasciata pictiventris) Colubrid Snakes

The axial skeleton, musculature and the waveform during swimming were examined for Nerodia f. pictiventris, a nonconstricting colubrid, and Elaphe g. guttata, a constricting colubrid. Both species possess qualitatively similar configurations of the segments of three major epaxial muscles (M. semispinalisspinalis, M. longissimus dorsi and M. iliocostalis). Segmental lengths of these three muscles of Elaphe are slightly less than or equal to those of Nerodia, whereas Elaphe has 50% more total vertebrae than Nerodia. Between the two species examined, no differences were found in waveform or maximum swimming velocity, whereas there were slight differences in the relation between relative swimming velocity and the frequency of wave propagation. For both species the amplitude and wavelength of the lateral undulations increased from anterior to posterior. Within each species, relative amplitude and relative wavelength tended to decrease slightly as swimming speed or snake size increased. For Nerodia the maximum absolute swimming velocity scaled with total snake length to the 0.6 power. For all snakes stability in the transverse plane increased with increased swimming speed. Snakes and anguilliform fish exhibited similar burst swimming velocities and a similar relationship between frequency of undulation and relative forward velocity.

Oxygen consumption during swimming in galapagos marine iguanas and its ecological correlates

1. Oxygen consumption, undulation frequency, and tether force as an index to power output were measured in tethered, swimming marine iguanas. 2. Power output increased linearly with total oxygen consumption and mass-specific oxygen consumption increased linearly with undulation frequency (Figs. 1 and 2). 3. Velocity of free swimming iguanas is a linear function of undulation frequency and of total length (Fig. 3), which allows calculation of the equivalent velocity for tethered iguanas undulating in place on a tether. 4. Cost of transport for swimming iguanas decreases as body mass increases, and can be predicted from the equation ml O2/kg·m=0.31M−0.56, whereM is mass in kg (Fig. 4). 5. The change in cost of transport with body mass correlates with foraging patterns of different size classes of marine iguanas. Small marine iguanas feed on algae on or near shore while adults obtain algae by swimming offshore and diving. 6. Cost of transport during swimming in marine iguanas is higher than for fish and turtles but lower than for ducks or humans (Fig. 5).

Echocardiographic correlates of atrial contraction in normal and abnormal atrial rhythm

Echocardiographic manifestations of normal atrial contraction on the left ventricular posterior wall (LVPW), ventricular septum (VS), right ventricular anterior wall (RVAW), and the aortic root have not been described previously in detail. In 150 consecutive echocardiograms recorded from patients in normal sinus rhythm, we have been able to find correlates of normal atrial contraction (A waves) on the LVPW in 130, on the VS in 95, on the RVAW in 27, and on the aortic root in 107. These waves occurred on the aortic root 0.04 0.06 sec after the onset of the P wave, and they occurred on the other cardiac structures 0.06 0.10 sec after the onset of the P wave. That these waves were due to atrial contraction was established by their close temporal relationship to the P wave in normal and abnormal atrioventricular (AV) conduction and by their absence whenever the QRS complex was not preceded by a P wave. First-degree AV block was associated with “premature” mitral closure. Premature atrial contractions produced definite A waves on the aortic root, but less distinct waves on the other structures. These echocardiographic correlates of atrial contraction provide another noninvasive means of assessing the atrial contribution to ventricular filling. Echocardiographic study of ten patients in atrial flutter showed that atrial flutter contractions produced regular undulations on the mitral valve leaflets, tricuspid valve leaflets, left ventricular posterior wall, ventricular septum, aortic root and cusps, and the anterior and posterior left atrial wall. Echocardiographic observations made in 40 patients in atrial fibrillation frequently showed undulations on the mitral and tricuspid valves, aortic root, pulmonary valve cusp, and left atrial anterior wall. In some instances, the diastolic undulations on the mitral valve leaflets showed only minimal variations in amplitude and frequency even though the simultaneously recorded electrocardiogram showed marked irregularity of amplitude and frequency of atrial undulations.

Frequency of Undulations on a Falling Water Film

An experimental study has been undertaken on the frequency of presented by the undulations occurring on the surface of a falling liquid film. The configuration of the film surface was observed by measuring the changes in the film thickness by means of a capacitometer. The flow regime was in the range of turbulent flow region, in which the undulations occur prominently and travel down along with the fluid film. The undulations proceed downward in an almost fixed pattern. The frequency of the passage of crests observed from a fixed point was evaluated from power spectral analysis to be about 20–30Hz, and this value changed very little with the Reynolds number and with heat flux applied to the falling liquid film. It is shown that this constancy of observed frequency is related to the fact that the large undulations move at the same velocity as the bulk of the fluid film, and that the speed of propagation is corresponding to a group velocity for ripples on the film surface.

Frequency of Undulations on a Falling Water Film

An experimental study has been undertaken on the frequency of presented by the undulations occurring on the surface of a falling liquid film. The configuration of the film surface was observed by measuring the changes in the film thickness by means of a capacitometer. The flow regime was in the range of turbulent flow region, in which the undulations occur prominently and travel down along with the fluid film. The undulations proceed downward in an almost fixed pattern. The frequency of the passage of crests observed from a fixed point was evaluated from power spectral analysis to be about 20–30Hz, and this value changed very little with the Reynolds number and with heat flux applied to the falling liquid film. It is shown that this constancy of observed frequency is related to the fact that the large undulations move at the same velocity as the bulk of the fluid film, and that the speed of propagation is corresponding to a group velocity for ripples on the film surface.

Behaviors of the leech, Placobdella, and transducer recordings of suctorial pressures

The leech habitually clings by hydrostatic suction (usually −2 to −5 cm H2O) generated between the posterior attachment organ and the substratum; there is also evidence that this organ secretes an adhesive. Spontaneous posterior attachment organ pressures associated with rhythmic body undulations and abduction–adduction movements were usually within this range. Subambient pressures (usually −2 to −4 cm H2O) were also recorded between the anterior attachment organ and the substratum. By manual abduction, the maximal pressures generated between the substratum and the posterior attachment organ were −90 ± 7 cm H2O. Similarly,−5 + 1 cm H2O was recorded from the anterior attachment organ.The frequency and amplitude of body undulations and of abduction–adduction movements increased in response to rising ambient temperature. During exploratory movements of the anterior attachment organ, the suction of the posterior attachment organ increased with trunk elongation and decreased with trunk shortening. Defensive posture, righting movements, and crawling are also discussed.

EFFECTS OF CENTRAL DEPRESSANTS AND STIMULANTS ON EEG ALTERATIONS INDUCED BY CAROTID COOLING AND WARMING

The influence of brain temperature changes upon the electroencephalogram (EEG) in the mammals has been reported by several investigators. Gaenshirt et al. (1) demonstrated that the spontaneous EEG recorded from isolated and artificially perfused cat's head showed marked changes in frequency and voltage at temperature varying from 40°C to 20°C, and that the mean frequency of the cortical EEG fell when the brain temperature was lowered down to 32°C, while mean voltage of the EEG increased when the temperature was lowered from 40°C to 33°C. However, the obvious correlation between the EEG activation and brain temperature was not inferred from their reports, because the perfused head would presumedly suffered from extreme non-physiological surgical procedures. von Euler and Soderberg (2) showed that moderate hypothalamic heating synchronized the EEG and inhibited the gamma motor activity in both rat and rabbit. Little work has hitherto been done to study the influence of drugs on synchronization and desynchronization of EEG caused by changes of brain temperature. In the previous reports, Tanabe and Takaori (3) observed the changes in temperature of brain, tympanic membrane and rectum, behavior, respiration, blood pressure and heart rate induced by cooling and warming both common carotid arteries in the rabbit. They reported that the carotid cooling produced alerting, shivering, pallor, increase in the respiratory frequency and depth, and increase in frequency and amplitude of the spontaneous undulation of the blood pressure, while the carotid warming caused drowsiness and slight increase in the heart rate. Further, they regarded the tympanic membrane temperature measured through the external auditory canal as a feasible reflexion of the brain temperature. The present experiments have been designed to elucidate the relationship between the brain temperature and the EEG's in the cortical and subcortical areas, and to trace the influence of central depressants and stimulants on the EEG alterations induced by the carotid cooling and warming.