High Beat Frequency Research Articles

Chemolithoheterotrophy in a metazoan tissue: thiosulfate production matches ATP demand in ciliated mussel gills.

The ribbed mussel Geukensia demissa inhabits sulfide-rich coastal sediments with a distribution that suggests a preference for exposure to sulfide. Although sulfide is a respiratory poison, it is also a potent reductant. Geukensia demissa gill mitochondria can use sulfide as a respiratory substrate for ATP production, and the gills of this species exhibit sulfide-supported oxygen consumption that matches the energy demand of ciliary beating. Here, we demonstrate (i) that the major product of G. demissa gill sulfide oxidation is thiosulfate and (ii) that the rate of sulfide oxidation also matches the cellular energy demand, resulting in a ratio near unity of oxygen consumed to sulfide oxidized at both low and high ciliary beat frequencies. A value for this ratio of unity is consistent with electrons from sulfide oxidation entering the mitochondrial electron transport chain. In the gills of the blue mussel Mytilus edulis from sulfide-free conditions, this ratio is 3-5 times higher, indicating an uncoupling of oxygen consumption from sulfide oxidation. Whereas M. edulis gills exhibit anaerobic metabolism during sulfide exposure, G. demissa gills do not, indicating a difference in sulfide tolerance between the two mussel species.

Bireflectance thin film in a high beat frequency laser

This paper investigates a kind of bireflectance thin film on the window plate of a 633 nm He–Ne laser. The film is coated on the substrate with the application of external load on it. The load on the substrate is removed after the coating has been accomplished, then the strain on the substrate will be transferred to the multilayer coatings. Due to photoelastic effect, the multilayer film becomes an anisotropic film. Selecting appropriate film structure and suitable center wavelength, a high phase dispersion with nearly constant reflectivity around the working wavelength will be obtained. For normal incidence, a sufficient phase shift difference between the two orthogonal polarization states of the reflected wave will be produced. As a result, a dual-frequency laser with a beat frequency of 5 MHz can be carried out by using this kind of multilayer film. The theory of designing such a film is emphasized and an example of bireflectance thin film is proposed.

Expression and Cellular Distribution of αvIntegrins inβ1 Integrin-deficient Embryonic Stem Cell-derived Cardiac Cells

β1integrin-deficient (β1−/−) ES cells showed increased differentiation of cardiac cells characterized by reduced adhesion and high beating frequency. Whereas in whole embryoid body outgrowths of β1−/−cells maximum levels ofαv , β3and β5integrin mRNA were delayed and transiently upregulated, in cardiac clusters isolated from β1−/−cells, onlyβ3 integrin mRNA levels were enhanced in comparison to wild-type (wt) cells. To answer the question, whetherαv and β3integrins may compensate, at least partially, the loss ofβ1 integrin function during cardiac differentiation, the distribution of αvandβ3 integrins in β1−/−and wt pacemaker-like cardiac cells was analyzed. A different distribution of αvand β3integrins inβ1−/−v wt cardiac cells was found. In wt cardiac cells,β1 integrin was localized in specialized subsarcolemmal regions, in particular, at focal contacts and costameres, but αvintegrin was diffusely distributed. In contrast, inβ1−/− cardiac cells, αvintegrin was preponderantly localized at cell membranes, focal contacts and costameres. β3integrin displayed a diffuse pattern both in wt and in β1−/−pacemaker-like cells at early differentiation stages, whereas at terminal stages, β3was colocalized with sarcomeres in wt, but not inβ1−/− pacemaker-like cells. Quantitative immunofluorescence analysis revealed increased αvand β3integrin levels inβ1−/− pacemaker-like cardiac cells. Our results led us to conclude that altered cellular distribution of αvintegrin and upregulation of β3integrin correlate with growth and survival of β1−/−cardiac pacemaker-like cells at an early developmental state. However, αvand β3integrins cannot functionally compensate the loss of β1integrin during terminal differentiation of cardiac cells implicating that cardiomyocytes require specific β1integrin functions for cardiac specialization.

Ultrastructure and motility of the caudal epididymis spermatozoa from the volcano mouse (Neotomodon alstoni alstoni Merriam, 1898)

The volcano mouse Neotomodon alstoni alstoni is a genus endemic to the higher elevations of the Mexican transvolcanic belt. In the present study we examined for the first time the morphological features of the spermatozoa taken from the caudal epididymis of this species by transmission and scanning electron microscopy. Spermatozoan motility was studied in sucrose and bicarbonate solutions; vitality and morphology were observed by light microscopy. Transmission electron microscopy shows that the head of spermatozoon is asymmetric and possesses a large and curved hook. The axoneme of the spermatozoan tail is highly developed at fibers 1, 5, and 6. Absolute and relative measurements of the length of the head, the midpiece, and the rest of the tail were also obtained. N. alstoni alstoni spermatozoa were hyperactive in the presence of 290 mM sucrose and 10 and 20 nM bicarbonate solutions exhibited high motility (180–190 μm/sec), and high flagellum beating frequency (10–12 Hz). In contrast, the spermatozoa in 310 mM sucrose solution showed scarce motility (13.5 ± 3.8 μm/sec) and low beating frequency (1.5 ± 0.4 Hz). It is proposed that the volcano mouse spermatozoa possess some features very similar to other mammalian spermatozoa and that bicarbonate triggers caudal epididymal sperm motility of this species. J. Exp. Zool. 287:316–326, 2000. © 2000 Wiley-Liss, Inc.

昆虫の飛行メカニズム

Flight mechanism of insect is different from that of our familiar system of aircraft, machinery, or bird. Recent studies quantitatively indicated that many features of insect flight mechanism, such as thin airfiol, high beating frequency, and continuous beating motion, well conform to the fluiddynamic condition given to the insect.

Ultrastructure and motility of the caudal epididymis spermatozoa from the volcano mouse (Neotomodon alstoni alstoniMerriam, 1898)

The volcano mouse Neotomodon alstoni alstoni is a genus endemic to the higher elevations of the Mexican transvolcanic belt. In the present study we examined for the first time the morphological features of the spermatozoa taken from the caudal epididymis of this species by transmission and scanning electron microscopy. Spermatozoan motility was studied in sucrose and bicarbonate solutions; vitality and morphology were observed by light microscopy. Transmission electron microscopy shows that the head of spermatozoon is asymmetric and possesses a large and curved hook. The axoneme of the spermatozoan tail is highly developed at fibers 1, 5, and 6. Absolute and relative measurements of the length of the head, the midpiece, and the rest of the tail were also obtained. N. alstoni alstoni spermatozoa were hyperactive in the presence of 290 mM sucrose and 10 and 20 nM bicarbonate solutions exhibited high motility (180-190 microm/sec), and high flagellum beating frequency (10-12 Hz). In contrast, the spermatozoa in 310 mM sucrose solution showed scarce motility (13.5 +/- 3.8 microm/sec) and low beating frequency (1.5 +/- 0.4 Hz). It is proposed that the volcano mouse spermatozoa possess some features very similar to other mammalian spermatozoa and that bicarbonate triggers caudal epididymal sperm motility of this species. J. Exp. Zool. 287:316-326, 2000.

Flight Mechanism of Insect. From Standpoint of View of Bio-Fluiddynamics.

Flight mechanism of insect is different from that of our familiar system of aircraft, machinery, or bird. Recent studies quantitatively indicated that many features of insect flight mechanism, such as thin airfoil, high beating frequency, or continuous beating motion, well conform to the fluiddynamic condition given to the insect.

The use of phosphocreatine plus ADP as energy source for motility of membrane-deprived trout spermatozoa.

Live trout spermatozoa initiate flagellar motility for a short period of time (30 s at 18 degrees C), during which their mean beat frequency (BF) decreases steadily from 60 to 20 Hz; motility then stops abruptly. When demembranated, the motility of axonemes lasts much longer, up to 20 min, with high beat frequency, provided that ATP (millimolar concentration) and cAMP (micromolar) are added. In the present paper, the motility of demembranated trout sperm was investigated in the absence of added ATP in various incubation conditions relative to other substrates. Without the addition of exogenous creatine kinase, the addition of phosphocreatine (PCr) and ADP shows the appearance of a progressive activation of all sperm models with BF increasing with time up to high values. Without the addition of cAMP, the BF increases to lower values but flagella propagated poorly coordinated waves for only a few min. Similar progressive activation is also observed when only ADP is added (without any previous in vivo activation) and BF increases up to moderate values. In this latter case, no activation occurs without addition of cAMP. The respective roles of creatine kinase and adenylate kinase in this process were investigated by addition of specific inhibitors such as fluorodinitrobenzene and P1,P5-di(adenosine-5')pentaphosphate in the above described conditions. We conclude from these observations that all the elements necessary for a coupling between ADP/PCr/creatine kinase on one hand and ATP/ADP/dynein on the other appear to be present in trout spermatozoa: thus the existence of a shuttle sustaining this coupling is strongly suggested.

Flagellar coordination in Chlamydomonas cells held on micropipettes.

The two flagella of Chlamydomonas are known to beat synchronously: During breaststroke beating they are generally coordinated in a bilateral way while in shock responses during undulatory beating coordination is mostly parallel [Rüffer and Nultsch, 1995: Botanica Acta 108:169-276]. Analysis of a great number of shock responses revealed that in undulatory beats also periods of bilateral coordination are found and that the coordination type may change several times during a shock response, without concomitant changes of the beat envelope and the beat period. In normal wt cells no coordination changes are found during breaststroke beating, but only short temporary asynchronies: During 2 or 3 normal beats of the cis flagellum, the trans flagellum performs 3 or 4 flat beats with a reduced beat envelope and a smaller beat period, resulting in one additional trans beat. Long periods with flat beats of the same shape and beat period are found in both flagella of the non-phototactic mutant ptx1 and in defective wt 622E cells. During these periods, the coordination is parallel, the two flagella beat alternately. A correlation between normal asynchronous trans beats and the parallel-coordinated beats in the presumably cis defective cells and also the undulatory beats is discussed. In the cis defective cells, a perpetual spontaneous change between parallel beats with small beat periods (higher beat frequency) and bilateral beats with greater beat periods (lower beat frequency) are observed and render questionable the existence of two different intrinsic beat frequencies of the two flagella cis and trans. Asynchronies occur spontaneously but may also be induced by light changes, either step-up or step-down, but not by both stimuli in turn as breaststroke flagellar photoresponses (BFPRs). Asynchronies are not involved in phototaxis. They are independent of the BFPRs, which are supposed to be the basis of phototaxis. Both types of coordination must be assumed to be regulated internally, involving calcium-sensitive basal-body associated fibrous structures.

Effect of Interferential Current on Perceived Pain and Serum Cortisol Associated with Delayed Onset Muscle Soreness

The purpose of this study was to assess the effect of interferential current (IFC) on perceived pain and serum Cortisol levels in subjects with delayed onset muscle soreness (DOMS). DOMS was induced in 10 subjects through repeated eccentric contractions of the elbow flexors. Forty-eight hours later subjects were evaluated. Starting at t = 0:00, blood samples were withdrawn from a superficial vein every 5 min for 65 min. At t = 0:05, subjects received IFC of 10 bps or IFC of 100 bps. Perceived pain levels were evaluated prior to catheter insertion and at t = 0:35, 0:50, and 0:65. Two mixed-model analyses of variance revealed a significant decrease in perceived pain scores across time for both treatment groups but no significant difference in serum Cortisol for the two groups. It was concluded that IFC of high and low beat frequency is effective in controlling the pain of DOMS but does not elicit a generalized stress response as indexed by increasing serum Cortisol levels.

A beat frequency buncher

A superconducting high energy buncher operating at 13 12 times the linac frequency has been built and installed, to combine with the low energy buncher operating at 1 12 the linac frequency. The system is synchronized so the linac and high energy buncher beat frequency remain in phase with the low energy buncher. On linac cycles not corresponding to a primary bunch, the high energy buncher bunches the residual beam away from the linac longitudinal acceptance rather than into it. The resonator for the new high energy buncher was constructed by shortening an existing low-β resonator.

Activation of mammalian sperm motility by regulation of microtubule sliding via cyclic adenosine 5'-monophosphate-dependent phosphorylation.

Bicarbonate was found to be essential for activating live mouse sperm motility. The activated sperm flagella exhibited high beat frequency, high swimming velocity, and large principal and reverse bends. To gain further insight into the bicarbonate-triggered activation mechanism, the microtubule sliding characteristics of the activated versus the nonactivated sperm flagella were compared by use of demembranated sperm. We found that the effects of bicarbonate on live sperm were identical with the effects of cAMP on demembranated sperm both in microtubule sliding velocity and in sliding disintegration pattern. Furthermore, autoradiography revealed that the activation of mouse sperm motility was associated with cAMP-dependent phosphorylation of a 65-kDa flagellar protein. The results demonstrated that bicarbonate-triggered activation of mouse sperm motility was closely coupled with the regulation of microtubule sliding via cAMP-dependent phosphorylation.

Some problems related to the assessment of sperm motility in freshwater fish

AbstractThe motility of the spermatozoa of freshwater fish is usually of short duration, but a precise description has rarely been provided. Motility requires a high dilution (more than 1,000‐fold) for initiation of synchronous motility in 100% of spermatozoa; a two‐step procedure is necessary, with an initial dilution of 1 to 100 in a medium that keeps the spermatozoa immotile and allows good mixing of the viscous semen. The second dilution (1 to 20) in the activating solution can be made directly under the microscope. Studies of carp sperm indicate that movement of live sperm is influenced by the ionic environment. The inhibition of motility in semen is mainly due to K+ ions in trout and osmotic pressure in carp, but other ions such as Na+, H+, and Mg2+ also interfere. Initiation of motility in trout requires external divalent cations. Immediately after dilution at 20°C, spermatozoa exhibit large circular trajectories (>400 μm in diameter), high beat frequencies (60 Hz), and velocities of 250 μm/sec. These values decrease rapidly. Within 20 sec after dilution, most spermatozoa stop moving, although some of them show some agitation with low beat frequency (< 10 Hz) and with very limited displacement during the next few minutes. A similar pattern is observed in carp, with active motility lasting 40 sec. Under certain ionic conditions, intratesticular spermatozoa are motile and have some fertilizing capacity.

Parametric laser-reception lidar

A theoretical analysis and design features of parametric CO(2) laser-reception lidar are reported. Stabilized regular laser radiation intensity oscillations are shown to occur under the laser-reception scheme of the return signal. Results are presented for low frequency cavity mirror oscillations and high instantaneous beat frequency. The laser radiation modulation structure observed suggests the feasibility of deriving information about the properties of the laser beam propagation medium.

Binaural interaction in low-frequency neurons in inferior colliculus of the cat. II. Effects of changing rate and direction of interaural phase

We used the binaural beat stimulus to study the interaural phase sensitivity of inferior colliculus (IC) neurons in the cat. The binaural beat, produced by delivering tones of slightly different frequencies to the two ears, generates continuous and graded changes in interaural phase. Over 90% of the cells that exhibit a sensitivity to changes in the interaural delay also show a sensitivity to interaural phase disparities with the binaural beat. Cells respond with a burst of impulses with each complete cycle of the beat frequency. The period histogram obtained by binning the poststimulus time histogram on the beat frequency gives a measure of the interaural phase sensitivity of the cell. In general, there is good correspondence in the shapes of the period histograms generated from binaural beats and the interaural phase curves derived from interaural delays and in the mean interaural phase angle calculated from them. The magnitude of the beat frequency determines the rate of change of interaural phase and the sign determines the direction of phase change. While most cells respond in a phase-locked manner up to beat frequencies of 10 Hz, there are some cells tht will phase lock up to 80 Hz. Beat frequency and mean interaural phase angle are linearly related for most cells. Most cells respond equally in the two directions of phase change and with different rates of change, at least up to 10 Hz. However, some IC cells exhibit marked sensitivity to the speed of phase change, either responding more vigorously at low beat frequencies or at high beat frequencies. In addition, other cells demonstrate a clear directional sensitivity. The cells that show sensitivity to the direction and speed of phase changes would be expected to demonstrate a sensitivity to moving sound sources in the free field. Changes in the mean interaural phase of the binaural beat period histograms are used to determine the effects of changes in average and interaural intensity on the phase sensitivity of the cells. The effects of both forms of intensity variation are continuously distributed. The binaural beat offers a number of advantages for studying the interaural phase sensitivity of binaural cells. The dynamic characteristics of the interaural phase can be varied so that the speed and direction of phase change are under direct control. The data can be obtained in a much more efficient manner, as the binaural beat is about 10 times faster in terms of data collection than the interaural delay.

Temperature Effects on the Beat Heating of a Collisional Magnetoplasma

AbstractThe beat heating of a magneto‐plasma by two antiparallel electromagnetic waves at different temperatures is examined. The effects of plasma temperature, plasma electron collisions, plasma ion collisions and magnitude and direction of the magnetic field on the excitation of plasma electron waves and plasma ion waves are studied. A formula for the power absorption density of the plasma by using Maxwell's equations in conjuction with continuity and momentum equation. including collisions and pressure tensor terms, is derived. The contribution of the plasma temperature to the power absorption density, both at low and high beat frequencies, of the collisional and the non‐collisional magnetised plasmas is found very significant and is illustrated numerically. The inclusion of pressure tensor term in the momentum equation is also found to cause characteristic changes in the power absorption density of the plasma with the orientation of magnetic field.

The perception of pure and mistuned musical fifths and major thirds: thresholds for discrimination, beats, and identification.

In Experiment 1, the discriminability of pure and mistuned musical intervals consisting of simultaneously presented complex tones was investigated. Because of the interference of nearby harmonics, two features of beats were varied independently: (1) beat frequency, and (2) the depth of the level variation. Discrimination thresholds (DTs) were expressed as differences in level (AL) between the two tones. DTs were determined for musical fifths and major thirds, at tone durations of 250, 500, and 1,000 msec, and for beat frequencies within a range of .5 to 32 Hz. The results showed that DTs were higher (smaller values of ΔL) for major thirds than for fifths, were highest for the lowest beat frequencies, and decreased with increasing tone duration. Interaction of tone duration and beat frequency showed that DTs were higher for short tones than for sustained tones only when the mistuning was not too large. It was concluded that, at higher beat frequencies, DTs could be based more on the perception of interval width than on the perception of beats or roughness. Experiments 2 and 3 were designed to ascertain to what extent this was true. In Experiment 2, beat thresholds (BTs) for a large number of different beat frequencies were determined. In Experiment 3, DTs, BTs, and thresholds for the identification of the direction of mistuning (ITs) were determined. For mistuned fifths and major thirds, sensitivity to beats was about the same. ITs for fifths and major thirds were not significantly different; deviations from perfect at threshold ranged from about 20 to 30 cents. Comparison of the different thresholds revealed that DTs are mainly determined by sensitivity to beats. Detailed analysis, however, indicated that perception of interval width is a relevant aspect in discrimination, especially for the fifths.

Physiological Thermoregulation in the Albacore Thunnus alalunga

Shipboard experiments demonstrate that the warm-bodied albacore tuna, Thunnus alalunga, uses physiological mechanisms to control heat loss and gain and is able to defend its body temperature (Tb) over a range of ambient temperatures (Ta). Thermocouple-implanted fish that were restrained yet capable of unhindered tail activity maintained stable red and white muscle temperatures (Trm and Twm) for from 15 to 160 min while exposed to Ta's ranging from 11.5 to 18.0 C. Below 11.5 C Ta, Trm and Twm could not be maintained and began to cool. Above 18.0 C Ta, both Trm and Twm increased with Ta in the pattern of a constant temperature excess (Tx = Tt − Ta), The mean Ta triggering thermoregulation was 13.6 C and the mean Trm at the initiation of thermoregulation was 19.7 C. Red and white muscle temperatures varied spatially and temporally. In one fish so tested brain temperature was not regulated while Trm was. All test albacore moved their tails at frequencies and amplitudes that would be sufficient to power a free-swimming fish at velocities needed for hydrostatic equilibrium. At low Ta's caudal fin activity was shifted to a higher frequency (+20%) and lower specific amplitude (from 13.6% to 8.6%l [fish fork length]). This mode of swimming favors thermoregulation because a higher beat frequency would produce more heat. It may also be less efficient and thus further contribute to heat production by requiring additional muscle fiber activity to power swimming. The albacore probably controls its heat balance by modulating retial exchange efficiency. This can occur in response to rapid increases or decreases in Ta and is also affected by a fish's recent thermal history, activity and Tb. High activity or swimming in warmer surface waters can increase the albacore's Tb. Shunting of cool blood around retia and to the body core via the dorsal aorta may be an important mechanism for preventing excessive heating or achieving rapid cooling upon return to a cooler Ta. In its natural environment, the albacore doubtlessly makes short forays into water with Ta's that are both above and below its range of physiological thermoregulation. Thermal imbalances resulting from this activity are probably compensated for by changes in heat exchange efficiency and the behavioral selection of a Ta that favors rapid restoration of thermal equilibrium.

Theory of stimulated Raman scattering in a dispersive medium

An analysis is made of the laws governing amplification of the Stokes wave in stimulated Raman scattering (STRS) in a dispersive medium for different models of wide-band pump radiation. An accurate solution of the STRS equations is obtained for pump radiation having a quadratically time-modulated phase. It is shown that for pump radiation for which the width of the instantaneous frequency spectrum is much less than the Raman scattering line width, the laws governing amplification of the Stokes wave differ substantially from those predicted by statistical STRS theory. Solutions of STRS equations in a dispersive medium are found for a model of temporally periodic pump radiation having a high intermode beat frequency.

Effects of viscosity and ATP concentration on the movement of reactivated sea-urchin sperm flagella.

Spermatozoa from the sea urchin, Lytechinus pictus, can be demembranated with solutions containing Triton X-100 and 5mM-CaCl2 and reactivated in ATP solutions containing low concentrations (10(-9)M) Of free Ca2+ ion to give symmetrical bending wave movements, even at very low ATP concentrations. At ATP concentrations of 0.01-0.02 mM the reactivated spermatozoa have beat frequencies near 1 Hz, nearly normal bend angles, and wave-lengths about 50% longer than normal. 2. The effects of increased viscosity, obtained by addition of methyl cellulose to the reactivation solutions, on bend angle and beat frequency decrease with decreasing ATP concentration, and become almost undetectable at 0.01 mM ATP. On the other hand, the effect of increased viscosity on wavelength shows relatively little change with ATP concentration, although it is noticeably reduced at 0.01 mM ATP. 3. These observations suggest that the beat frequency at low ATP concentrations is determined by an intrinsic rate-limiting process, in contrast to the viscocity-limited behaviour at high beat frequencies. Quantitative agreement with the experimental results is obtained with a model in which ATP concentration and viscosity each determine the rates of one step in a two-step reaction cycle which determines the beat frequency. 4. Two other models which can qualitatively explain the effects of ATP concentration and viscosity on flagellar beat frequency fail to show quantitative agreement with the experimental results. In one of these models, ATP concentration determines the maximum rate of shear between filaments. In the other, ATP concentration determines a time delay which is required to bring the active moment into phase with the elastic moments which would be expected to dominate the bending resistance at low beat frequencies.