Spring Apparatus Research Articles

Agonistic sounds and swim bladder morphology in a malapterurid electric catfish

AbstractSeveral catfish families possess an elastic spring apparatus (ESA) morphology that is assumed to function as a swim bladder drumming sound production mechanism. Although they have an ESA, drumming sounds in the electric catfish (Malapteruridae) have not been described. We have recorded several different sound types in Malapterurus beninensis and we examined the morphology of the swim bladder, the ESA and the ultrastructure of the protractor muscle. The protractor muscle contains small rounded muscle fibers with abundant mitochondria, narrow myofibrils, elaborated sarcoplasmic reticula and sometimes sarcoplasmic cores. Contractions of the protractor muscle should pull the Müllerian ramus (MR) and attached swim bladder anteriorly. Further, the MR possesses an anterior fulcrum that abuts upon the vertebral complex. Several sound types were elicited during agonistic interactions in the laboratory. We observed ratchet, click train and mouth sounds. Mouth sounds are single event, low‐frequency (mean dominant frequency 176 Hz) sounds that coincide with a bite‐like motion. Ratchet and click sounds are high‐frequency (mean dominant frequency 1568 and 3739 Hz, respectively) and occur in trains. Ratchet and click train sound characteristics are not indicative of a muscle‐driven drumming sound predicted by ESA morphology. We propose several hypotheses for these sound production mechanisms. Click sounds, in particular, could result from gas movement through the neck between the anterior and posterior swim bladder chambers.

Attempt toward a development of aquatic exercise device for gait disorders

Purpose: To develop an aquatic exercise device to facilitate locomotive motor output and achieve repetitive physiological gait patterns to improve movement dysfunctions. Methods: A custom designed leg movement apparatus (LMA) consisted of closed 4-linkage mechanisms and one-length changeable link using a spring. Three-dimensional motions and electromyographic (EMG) activities were recorded in eight healthy subjects to evaluate the reproducibility of the physiological gait patterns using the LMA with or without a spring apparatus in water. Results: Using the LMA with a spring apparatus compared to walking in water, the foot trajectories and the time course of the elevation angles in each lower limb joint kinematics were preserved. The time-series of the EMG showed reciprocal modulation between agonist and antagonist muscle groups in the hip and ankle joints. However, the amplitudes of the tibialis anterior muscle in the first half and rectus femoris in the last half of the movement cycle were reduced using the LMA with a spring apparatus. Conclusion: We developed a novel aquatic exercise device to reproduce physiological gait patterns. The LMA with a spring apparatus would be particularly valuable in therapy for movement dysfunctions to facilitate locomotive motor outputs.Implications for RehabilitationThe leg movement apparatus with spring for underwater use (LMA) would be effective gait training to induce the locomotor-like EMG activities.Hydrotherapy with the LMA has advantages over the partial body weight support treadmill training on land with a robotic device; (1) the LMA is electrically and mechanically safe, and (2) the LMA would require self-effort to generate the gait pattern for movement disorders, or also enable passive gait training by the physiotherapists.

One and two degrees-of-freedom Vortex-Induced Vibration experiments with yawed cylinders

Vortex-Induced Vibration (VIV) experiments were carried out with yawed cylinders. The purpose was to investigate the validity of the Independence Principle (IP) for properly describing the flow characteristics and the dynamics of structures subjected to oblique flow. Five yaw angles in relation to the direction perpendicular to the free stream velocity were tested, namely θ=0°,10°,20°,30° and 45°. Both the upstream and downstream orientations were tested. The models were mounted on a leaf spring apparatus that allows experiments with one or two degrees of freedom. The Reynolds numbers based on the component normal to the cylinder axis fell in the interval 3×103<Ren<1.5×104. The mass ratio parameter was m⁎=2.6 and the cylinder aspect ratio was L/D≈13 for all the experiments. Time histories of displacement and hydrodynamic forces were acquired. Considering only the component of the free stream which is normal to the cylinder axis, the results of amplitude and force coefficients agreed reasonably well with the non-yawed ones for yaw angles up to 20° for both one and two degrees-of-freedom experiments. This indicates the validity of the IP for this yaw angle range. For yaw angles larger than 20°, a decrease in the maximum amplitude was observed. The decrease in the oscillation amplitudes was related to a larger modulation in the phase shift between force and displacement. Differences in the results for upstream and downstream were observed and were more evident for the larger yaw angle. These differences can be associated to the asymmetric cylinder end conditions.

Nonlinear vibration of a magnetic spring

To demonstrate the different vibration characteristics of a magnetic spring compared withthose of a metal one, a magnetic spring apparatus was constructed from a pair of circularmagnets of the same size with an inside diameter of 2.07 cm and an outside diameter of4.50 cm. To keep the upper magnet in a suspension state, the two magnets wereplaced vertically on a ceramic rod, with the same polarity sides facing against oneanother. The variation of magnetic field, resulting from the oscillation of theupper magnet, was recorded online with the aid of a magnetic field sensor and adata acquisition computer. It showed that the repulsion force has a nonlineardependence on the gap between the two magnets in the form of a polynomial of powerseries.

Bioacoustic variation of swimbladder disturbance sounds in Neotropical doradoid catfishes (Siluriformes: Doradidae, Auchenipteridae): Potential morphological correlates

Abstract Swimbladder disturbance sounds of doradoid catfishes (Doradidae and Auchenipteridae) demonstrated striking waveform and spectrographic variation. We surveyed sounds of 25 doradoid species in 20 genera comparing these to sounds of four vocal outgroup catfish families. Sounds were either continuous waveforms (lacking interpulses) or pulsed (groups of pulses repeated at fixed temporal intervals). This is the first evidence for swimbladder calls with fixed interpulse patterns in catfishes. Vocal mechanism components that were similar between doradids and auchenipterids included: swimbladder shape, swimbladder dimensions and sonic muscle-somatic index. Morphological traits that showed variation among taxa and were evaluated for potential correlates of call diversity are: 1) diverticula (marginal outpocketings of the swimbladder with no connection to inner ear) and 2) elastic spring apparatus Müllerian rami (ESA-Mr). Within the doradid subfamilies and within the Auchenipteridae most species differed significantly in dominant frequency with frequency ranges overlapping to some extent for most. Doradid swim-bladder diverticula did not explain dominant frequency variation within the doradoid superfamily. Some doradids with conical ESA-Mr had the highest dominant frequency sounds. Auchenipterids included both relatively lower and higher dominant frequency sound producers but lacked diverticula and had discoidal ESA-Mr. Comparing a phylogeny of doradoid genera with out-group taxa, we infer that complex diverticula and conical ESA-Mr are derived characters within the Doradidae. Species representing outgroup families produced either continuous lower dominant frequency sounds (aspredinids, mochokids and pseu-dopimelodids) or pulsed higher dominant frequency sounds (pimelodids).

Raman Piezospectroscopy of Phonons in Bulk 6H-SiC

Raman piezospectroscopy of high quality 6H-SiC crystals is presented. The crystals used in experiments were grown by the seeded physical vapor transport method. Uniaxial stress up to 0.9 MPa, obtained using a spring apparatus, was applied along [11–20] and [10–10] directions. It was found that the application of uniaxial stress led to different energy shifts of the observed phonon excitations in the investigated 6H-SiC crystals. The obtained pressure coefficients vary in the range 0.98–5.5 cm−1 GPa−1 for different transverse optical phonon modes. For longitudinal optic phonon modes pressure coefficients in the range 1.6–3.6 cm−1 GPa−1 were found. The data obtained could be useful in evaluation of local strain fields in SiC based structures and devices including epitaxial graphene.

Correlation between milling and baking parameters of wheat varieties

The milling and baking parameters of flours from foreign and Czech varieties were determined and related to milling and baking performance by correlation analysis. Twenty samples of wheat from the international breeding test CIMMYT (harvest year 2003) were used. Standard milling test at CD1 auto mill confirmed expressive different milling parameters of single varieties. Rheological properties of flours in dough were assessed at farinograph, extensigraph, fermentograph SJA, maturograph and oven spring apparatus. Baking test was also performed. Significant correlation was obtained between the milling parameters, grain hardness, flour water absorption and specific bread volume. The significant correlation was found between water absorption and yield of semolina (r=0.79); fermentograph gases volume and yield of semolina (r=0.89), farinograph water absorption (r=0.77), kernel hardness (r=0.76); specific bread volume and flour protein content (r=0.57), the yield of semolina (r=0.57). The most related section correlation was found between maturograph dough resistance and final dough volume on fermentograph (r=0.70).

Catfishes as a case study for discussions on general evolution: the importance of functional uncouplings in morphological macroevolution.

Many evolutionary biologists have stressed that functional uncouplings play an important role in morphological macroevolution, as they facilitate diversification and speciation by increasing the number of degrees of freedom and allowing more mechanical solutions for functional problems. In the present paper, the importance of functional uncouplings in the evolution of six major catfish structural complexes is briefly discussed, namely those constituted by the mandibular barbels and associated structures, the pectoral girdle complex, the elastic spring apparatus, the suspensorium, the palatine-maxillary system, and the adductor mandibulae complex. The overview of these major structural complexes indicates that functional uncouplings did effectively play an essential role on catfish evolutionary history. The study of this cosmopolitan and particularly diverse group representing about one-third of all freshwater fishes thus supports the importance of functional uncouplings in morphological macroevolution.

Competitive effects in the adsorption of CH 3I on KI-impregnated activated carbons in the presence of CO 2

This paper describes an investigation of the adsorption of CH 3I on a KI-impregnated carbon and the influence of competitive adsorption on the process. A gravimetric method was used to study the equilibrium capacity and kinetics for the adsorption of CO 2 and CH 3I in the presence of He, and CH 3I in the presence of CO 2 on the carbon. The results of these experiments were compared with those obtained from measurements carried out using a McBain spring apparatus to obtain the equilibrium uptake of CH 3I vapour on the KI-impregnated carbon at 293 K. The adsorption kinetic results covering the range 275–333 K show that the rates of adsorption are only weakly dependent on the temperature. The apparent activation energies for adsorption of CO 2 and CH 3I in the presence of He, and CH 3I in the presence of CO 2 were 20.0 ± 1.1, 6.5 ± 0.3 and 10.0 ± 0.5 kJ mol −1, respectively. The rates of adsorption of CH 3I in the presence of CO 2 were about half the corresponding rate of the adsorption of CH 3I in the presence of He. However, the equilibrium capacities were very similar in both cases. Adsorption experiments carried out over a CH 3I partial pressure range, 3.08–38.5 kPa in CO 2 showed that the initial adsorption rate constant was linearly dependent on the CH 3I concentration. The results are discussed in terms of competitive adsorption in the CH 3I-CO 2 system.

A SINGLE KERNEL CREEP AND RECOVERY TEST

ABSTRACT Creep and recovery tests were performed with single canola kernels using spring apparatus in conjunction with a common universal testing machine. An apparent modulus of elasticity and viscosity coefficients for Maxwell and Kelvin model in series were determined. The test data were compared with published data. The advantages of the spring apparatus for measuring a creep and recovery behavior for single kernels were discussed based on results obtained.

Phylogenetic Relationships among the Catfish Genera of the Family Auchenipteridae (Teleostei: Siluroidea)

The Auchenipteridae is a neotropical freshwater catfish family composed of over 60 species in 21 genera. It is diagnosed as a monophyletic group on the basis of three synapomorphies: 1) a post-epioccipital process that reaches the nuchal plates or vertebral column: 2) a genital papilla formed with modified rays of the anal fin: and 3) a unique groove that holds the maxillary barbel under the eye. The sister group to the Auchenipteridae is hypothesized to be the Doradidae, a relationship supported by the following five synapomorphies: 1) anterior attachment of the elastic spring apparatus to the wall of the swimbladder; 2) prominent epioccipitals that join the nuchal plates; 3) extreme development of the post-cleithral process; 4) three nuchal plates; and 5) unique arrangement of the neural spines and proximal radials of the dorsal-fin rays. Species representing 19 genera were examined and 24 morphological characters were used in a cladistic analysis of the Auchenipteridae. The most parsimonious tree had only one homoplastic character but it is not completely resolved.

Transthoracic resistance in human defibrillation. Influence of body weight, chest size, serial shocks, paddle size and paddle contact pressure.

Successful defibrillation depends on delivery of adequate electrical current to the heart; one of the major determinants of current flow is transthoracic resistance (TTR). To study the factors influencing TTR, we prospectively collected data from 44 patients undergoing emergency defibrillation. Shocks of 94-450 J delivered energy were administered from specially calibrated Datascope defibrillators that displayed peak current flow, thereby permitting determination of TTR. Shocks were applied from standard (8.5-cm diameter) or large (13 cm) paddles placed anteriorly and laterally. First-shock TTR ranged from 15-143 omega. There was a weak correlation between TTR and body weight (r = 0.45, p less than 0.05) and a stronger correlation between TTR and chest width (r = 0.80, p less than 0.01). Twenty-three patients who were defibrillated using standard 8.5-cm paddles had a mean TTR of 67 +/- 36 omega (+/- SD), whereas 21 patients who received shocks using paddle pairs with at least one large (13 cm) paddle had a 21% lower TTR of 53 +/- 24 omega (p = 0.05, unpaired t test). Ten patients received first and second shocks at the same energy level; TTR declined only 8%, from 52 +/- 19 to 48 +/- 16 omega (p less than 0.01, paired t test). In closed chest dogs, shocks were administered using a spring apparatus that regulated paddle contact pressure against the thorax. Firmer contact pressure caused TTR to decrease 25%, from 48 +/- 22 to 36 +/- 17 omega (p less than 0.01, paired t test). Thus, human TTR varies widely and is related most closely to chest size. TTR declines only slightly with a second shock at the same energy level. More substantial reductions in TTR and declines only slightly with a second shock at the same energy level. More substantial reductions in TTR and increases in current flow can be achieved by using large paddles and applying firm paddle contact pressure.