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Wave Patterns (wave + pattern)
Selected AbstractsNa+/Ca2+ exchanger modulates the flagellar wave pattern for the regulation of motility activation and chemotaxis in the ascidian spermatozoaCYTOSKELETON, Issue 10 2006Kogiku Shiba Abstract Ion channels and ion exchangers are known to be important participants in various aspects of sperm physiology, e.g. motility activation, chemotaxis, the maintenance of motility and the acrosome reaction in the sperm. We report here on a role of the K+ -independent Na+/Ca2+ exchanger (NCX) on ascidian sperm. Reverse-transcriptase PCR reveals that the NCX is expressed in the testis while immunoblotting and immunolocalization demonstrate that the NCX exists on the sperm in the ascidian Ciona savignyi and C. intestinalis. A potent blocker of the NCX, KB-R7943 was found to block sperm-activating and -attracting factor (SAAF)-induced motility activation, sperm motility and sperm chemotaxis. We further analyzed the effects of this blocker on motility parameters such as the flagellar waveform, curvature, beat frequency, amplitude and wavelength of the sperm flagella. Inhibition of the NCX caused two distinct effects: a low concentration of KB-R7943 induced symmetric bending, whereas a high concentration of KB-R7943 resulted in asymmetric flagellar bending. These findings suggest that the NCX plays important roles in the regulation of SAAF-induced sperm chemotaxis, motility activation and motility maintenance in the ascidian. This study provides new information toward an understanding of Ca2+ transport systems in sperm motility and chemotaxis. Cell Motil. Cytoskeleton 2006. © 2006 Wiley-Liss, Inc. [source] Computation of turbulent free-surface flows around modern shipsINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS, Issue 4 2003Tingqiu Li Abstract This paper presents the calculated results for three classes of typical modern ships in modelling of ship-generated waves. Simulations of turbulent free-surface flows around ships are performed in a numerical water tank, based on the FINFLO-RANS SHIP solver developed at Helsinki University of Technology. The Reynolds-averaged Navier,Stokes (RANS) equations with the artificial compressibility and the non-linear free-surface boundary conditions are discretized by means of a cell-centred finite-volume scheme. The convergence performance is improved with the multigrid method. A free surface is tracked using a moving mesh technology, in which the non-linear free-surface boundary conditions are given on the actual location of the free surface. Test cases recommended are a container ship, a US Navy combatant and a tanker. The calculated results are compared with the experimental data available in the literature in terms of the wave profiles, wave pattern, and turbulent flow fields for two turbulence models, Chien's low Reynolds number k,,model and Baldwin,Lomax's model. Furthermore, the convergence performance, the grid refinement study and the effect of turbulence models on the waves have been investigated. Additionally, comparison of two types of the dynamic free-surface boundary conditions is made. Copyright © 2003 John Wiley& Sons, Ltd. [source] Climate variability in Malawi, part 1: dry summers, statistical associations and predictabilityINTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 11 2002M. R. Jury Abstract Climate variability and predictability over tropical southern Africa is studied using a Malawi summer rainfall index. Thermodynamic and circulation patterns are examined and statistical associations are analysed. Links with El Niño,southern oscillation (ENSO) and quasi-biennial oscillation (QBO) phase are significant and consistent with those found for southern Africa. Correlations are mapped with respect to the Malawi rainfall index, and the regional expression of ENSO emerges quite clearly. Negative r values for sea-surface temperature (SST) in the west Indian Ocean contrast with positive r values in the east Atlantic and Agulhas region. The thermodynamic pattern ,anchors' a standing Rossby wave, comprised of northwest,southeast-oriented centres of action across the Mozambique Channel and southern Africa, and east of Madagascar to East Africa. A meandering of the sub-tropical jet stream is an expression of the standing Rossby wave, leading to vertical motions over southern Africa. The pattern develops at least one season in advance, and predictive indices are extracted in the July,September season for use in a multivariate model to predict the Malawi summer rainfall. The three-area SST index, formulated to capture the ENSO-modulated Rossby wave pattern, is the most influential predictor, followed by air pressure over the east Indian Ocean and the stratospheric zonal wind anomaly (QBO). Skilful results are found, with a 55% hindcast fit and two-thirds of tercile categories correctly forecast in independent tests. Copyright © 2002 Royal Meteorological Society. [source] Click and Low-, Middle-, and High-Frequency Toneburst Stimulation of the Canine CochleaJOURNAL OF VETERINARY INTERNAL MEDICINE, Issue 3 2002G. Ter Haar A method was developed to deliver tonebursts ranging in frequency from 1 to 32 kHz for frequency-specific assessment of the canine cochlea. Brainstem auditory-evoked responses (early latency responses, 0,10 ms) to a click (CS) and to 1-, 2-, 4-, 8-, 12-, 16-, 24-, and 32-kHz toneburst stimulations (TS) were compared at 80-dB sound pressure level stimulus (SPL) intensity in 10 adult dogs. All stimulations yielded a 5,7 positive wave pattern, with the exception of the 1-kHz TS, which evoked a frequency-following response (FFR). Thresholds were lowest for the CS and the 12- and 16-kHz TS. All individual peak latencies for TS were significantly (P, .05) longer than for CS. Peak I latencies were significantly (P,.05) shorter for the 12- and 16-kHz TS than for the other TS. Interpeak latencies I-V were significantly (P, .05) longer for the 4- to 32-kHz TS than for CS. Differences in interpeak latencies I,III were not significant. Amplitudes of waves I and V were significantly (P, .05) lower for TS than for CS, except for higher wave V amplitude (P, .05) at 2- and 32-kHz TS. Peak I-V amplitude ratios were significantly (P, .05) higher for the 2-, 4-, 16-, 24-, and 32-kHz TS and lower for the 8- and 12-kHz TS, compared to CS. We conclude that reproducible information on frequency specificity of the canine cochlea can be obtained by TS. This report provides a normative database for parameters needed to evaluate frequency-specific hearing loss in dogs. [source] A simplified model of gas,liquid two-phase flow pattern transitionHEAT TRANSFER - ASIAN RESEARCH (FORMERLY HEAT TRANSFER-JAPANESE RESEARCH), Issue 7 2004Koji Ito Abstract An experiment of upward gas,liquid two-phase flow was conducted in an air,water isothermal system under atmospheric pressure. The differential pressure was measured at the fully developed section by using a variable reluctance type transducer to classify the flow patterns and their transitions. The flow behavior was observed with a high-speed video camera. The probability density function (PDF) of the differential pressure signal was employed to identify the flow pattern. A simplified one-dimensional flow model was proposed to clarify dominant factors affecting the formation and transitions of flow patterns. The model dealt with the gas-component advection based on the spatiotemporal void fraction behaviors by considering the gas compressibility, the wake, and the liquid phase redistribution mechanism. The simulation results of the model indicated four kinds of the void wave patterns (ripple-like, rectangular, distorted rectangular, and uniform wave patterns) depending on gas and liquid volumetric fluxes. These void wave patterns corresponded well to the experimentally observed flow patterns. The transitions among void wave patterns agree well with the Mishima,Ishii flow pattern map. The friction loss estimated by the present model coincides fairly well with Chisholm's empirical formula. © 2004 Wiley Periodicals, Inc. Heat Trans Asian Res, 33(7): 445,461, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.20029 [source] Analysis of nutritive sucking function in very low and extremely low birthweight infants in Japan: A pilot studyJAPAN JOURNAL OF NURSING SCIENCE, Issue 1 2005Manami MATSUBARA Abstract Aim:, The purpose of the present study was to investigate the differences in nutritive sucking patterns between very low, extremely low birth-weight infants (LBWI) and full-term infants (FTI) and to examine the change in those sucking patterns within 5 months after birth. Methods:, Sucking patterns of eight LBWI and seven FTI were compared. In addition, sucking patterns were measured in four of the LBWI and seven of the FTI until 5 months of age to determine change in sucking wave patterns over time. Results:, During the first month after birth, there was a significant difference in the sucking wave between the LBWI and FTI. The sucking cycle time was significantly shorter and the intensity of the sucking pressure was significantly smaller in the LBWI than that in the FTI. By 5 months, significant correlations were noted between the actual age or the modified age and the sucking pressure in both LBWI and FTI. Conclusions:, The findings suggest that the weakness of oral muscular function and less sucking skill can bring about the weakness of intensity of sucking pressure, decreased time of the sucking stage in a sucking cycle, and unstable intensity of sucking pressure and time of the sucking stage in LBWI infants, causing low efficiency of milk intake and smaller amounts of milk swallowing during each sucking period as they obstructs the development of oral muscular function itself. These problems last for a longer period of time in LBWI than in FTI, leading to a deficit in the development of masticatory function in LBWI. The results of the current pilot study will serve as a foundation to investigate the development of masticatory function in LBWI as they grow into early childhood. [source] Two Coexisting Modes in Field-Assisted AFM Nanopatterning of Thin Polymer FilmsMACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 13 2008Xian Ning Xie Abstract Two coexisting mechanisms, i.e., electrohydrodynamic destabilization and electrostatic detachment, for polymer nanostructuring in field-assisted atomic force microscope nanolithography are presented. The electrohydrodynamic destabilization mechanism is based on the surface instability of molten polymer film in the form of surface waves, and it leads to the formation of well defined polymeric wave patterns. The electrostatic detachment mechanism is associated with nano-blister formation caused by pre-existing defects, such as buried cavities in the polymer, and is responsible for the creation of hollow pillar-like structures. Here, the coexistence and pattern formation probability of the two polymer patterning modes under similar nanolithographic conditions are discussed. It was found that the field strength and the efficiency of probe-induced joule heating can significantly change the flow property of the polymer, which eventually leads to the occurrence of the two modes. The results presented here are useful in obtaining a complete picture of the diverse behaviors of polymers in AFM nanolithographic operations. [source] The global response to tropical heating in the Madden,Julian oscillation during the northern winterTHE QUARTERLY JOURNAL OF THE ROYAL METEOROLOGICAL SOCIETY, Issue 601 2004Adrian J. Matthews Abstract A life cycle of the Madden,Julian oscillation (MJO) was constructed, based on 21 years of outgoing long-wave radiation data. Regression maps of NCEP,NCAR reanalysis data for the northern winter show statistically significant upper-tropospheric equatorial wave patterns linked to the tropical convection anomalies, and extratropical wave patterns over the North Pacific, North America, the Atlantic, the Southern Ocean and South America. To assess the cause of the circulation anomalies, a global primitive-equation model was initialized with the observed three-dimensional (3D) winter climatological mean flow and forced with a time-dependent heat source derived from the observed MJO anomalies. A model MJO cycle was constructed from the global response to the heating, and both the tropical and extratropical circulation anomalies generally matched the observations well. The equatorial wave patterns are established in a few days, while it takes approximately two weeks for the extratropical patterns to appear. The model response is robust and insensitive to realistic changes in damping and basic state. The model tropical anomalies are consistent with a forced equatorial Rossby,Kelvin wave response to the tropical MJO heating, although it is shifted westward by approximately 20° longitude relative to observations. This may be due to a lack of damping processes (cumulus friction) in the regions of convective heating. Once this shift is accounted for, the extratropical response is consistent with theories of Rossby wave forcing and dispersion on the climatological flow, and the pattern correlation between the observed and modelled extratropical flow is up to 0.85. The observed tropical and extratropical wave patterns account for a significant fraction of the intraseasonal circulation variance, and this reproducibility as a response to tropical MJO convection has implications for global medium-range weather prediction. Copyright © 2004 Royal Meteorological Society [source] Differences in the morphology and duration between premature P waves and the preceding sinus complexes in patients with a history of paroxysmal atrial fibrillationCLINICAL CARDIOLOGY, Issue 7 2003Polychronis E. Dilaveris M.D. Abstract Background: Atrial fibrillation (AF) is the most common arrhythmia encountered in clinical practice. Experimental and human mapping studies have demonstrated that perpetuation of AF is due to the presence of multiple reentrant wavelets with various sizes in the right and left atria. Hypothesis: Atrial fibrillation may be induced by atrial ectopic beats originating in the pulmonary veins, and premature P-wave (PPW) patterns may help to identify the source of firing. Methods: To evaluate the morphology and duration of PPWs, 12-lead digital electrocardiogram (ECG) strips containing clearly definable PPWs not merging with the preceding T waves were obtained in 25 patients with AF history (9 men, mean age 59.5 ± 2.2 years) and 25 subjects without any previous AF history (11 men, mean age 53.6 ± 2.5 years). The polarity of PPWs was evaluated in all 12 ECG leads. Previously described indices, such as P maximum, P dispersion (= P maximum ,P minimum), P mean, and P standard deviation were also calculated. Results: Premature P-wave patterns were characterized by more positive P waves in lead V1. All P-wave analysis indices were significantly higher in patients with AF than in controls when calculated in the sinus beat, whereas they did not differ between the two groups when calculated in the PPW. P-wave indices did not differ between the PPW and the sinus P wave in either patients with AF or controls, except for P mean, which was significantly higher in the sinus (110.1 ± 1.7 ms) than in the PPW (100 ± 2 ms) only in patients with AF (p = 0.001). Conclusion: The evaluation of PPW patterns is only feasible in a small percentage of short-lasting digital 12-lead ECG recordings containing ectopic atrial beats. Premature P wave patterns are characterized by more positive P waves in lead V1, which indicates a left atrial origin in the ectopic foci. The observed differences in P-wave analysis indices between patients with AF and controls and between sinus beats and PPWs may be attributed to the presence of electrophysiologic changes in the atrial substrate. [source] | ||||||||||||||||