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Journal articles on the topic 'Amplitude variation'
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1
Yu, Gary. "Offset‐amplitude variation and controlled‐amplitude processing." GEOPHYSICS 50, no. 12 (December 1985): 2697–708. http://dx.doi.org/10.1190/1.1441890.
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The partition of plane seismic waves at plane interfaces introduces changes in seismic amplitude which vary with angle of incidence. These amplitude variations are a function of the elastic parameters of rocks on either side of the interface. Controlled‐amplitude processing is designed to obtain the true amplitude information which is geologic in origin. The offset‐amplitude information may be successfully used to predict the fluid type in reservoir sands. Various tests were carried out on a seismic profile from the Gulf Coast. The processing comparison emphasized the effects and pitfalls of trace equalization, coherent noise, offset, and surface‐related problems. Two wells drilled at amplitude anomaly locations confirmed the prediction of hydrocarbons from offset‐amplitude analysis. Furthermore, controlled‐amplitude processing provided clues in evaluating reservoir quality, which was not evident on the conventional relative amplitude data.
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Neidell, Norman S. "Amplitude variation with offset." Leading Edge 5, no. 3 (March 1986): 47–51. http://dx.doi.org/10.1190/1.1439241.
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Li, Jun, H. Jay Zwally, Helen Cornejo, and Donghui Yi. "Seasonal variation of snow-surface elevation in North Greenland as modeled and detected by satellite radar altimetry." Annals of Glaciology 37 (2003): 233–38. http://dx.doi.org/10.3189/172756403781815889.
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AbstractComparison of the distribution of seasonal variations in surface elevation derived from a firn-densification–elevation model with observed variations derived from ERS-1/-2 satellite radar altimetry shows close similarity in the patterns of the amplitude of the variations over the North Greenland ice sheet. The amplitudes of the seasonal variations decrease from west to east and from south to north, determined by the accumulation rate and the surface-temperature distribution pattern. Several methods of estimating the amplitude of the seasonal variation in the observations are compared, including the use of a three-frequency sinusoidal function derived from the modeled seasonal variation that is asymmetric. The resulting correlation coefficient between the observed amplitude, estimated with the three-frequency function, and the modeled amplitude is 0.66 and the slope is 0.7. Residual differences may be caused by interannual variability in accumulation and temperature and other approximations in the model.
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Carey, M. G., S. S. Al-Zaiti, T. M. Kozik, H. Schell-Chaple, and M. M. Pelter. "QRS Amplitude Variation During Monitoring." American Journal of Critical Care 25, no. 1 (December 31, 2015): 97–98. http://dx.doi.org/10.4037/ajcc2016791.
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Szabados, L. "New Ways of Revealing Cepheid Binaries." International Astronomical Union Colloquium 139 (1993): 406–7. http://dx.doi.org/10.1017/s0252921100118068.
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AbstractTwo methods involving the observed amplitudes of radial velocity and UBVR light variations for classical Cepheids have been analysed, both being implicitly known: their principle is trivial but these methods had not yet been used systematically as indicators of duplicity.The slope method is based on the alteration of the wavelength dependence of the light variation amplitude if either a blue or a red companion is added to the light of the Cepheid. The amplitude ratio (AR) method makes use of the fact that the companion reduces the amplitude of the light variation without observable effect on the pulsational radial velocity amplitude. This means that the ratio of these two amplitudes (Arad.vel./AB) has a larger value for binary Cepheids as compared with the single pulsators.Each method has been applied to more than 100 Cepheids, thus allowing to study how the uncontaminated parameters (amplitude ratio and slope) depend on the pulsation period. Binary Cepheids deviate from the regular pattern in these diagrams, and a number of new binaries can be discovered in this way. The effect of duplicity is revealed by both methods independently for VZ CMa, FM Cas, CR Cep, V402 Cyg, VI154 Cyg, V440 Per and DR Vel.
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Deepa, V., G. Ramkumar, M. Antonita, K. K. Kumar, and M. N. Sasi. "Vertical propagation characteristics and seasonal variability of tidal wind oscillations in the MLT region over Trivandrum (8.5° N, 77° E): first results from SKiYMET Meteor Radar." Annales Geophysicae 24, no. 11 (November 21, 2006): 2877–89. http://dx.doi.org/10.5194/angeo-24-2877-2006.
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Abstract. Tidal activity in the Mesospheric Lower Thermosphere (MLT) region over Trivandrum (8.5° N, 77° E) is investigated using the observations from newly installed SKiYMET Meteor Radar. The seasonal variability and vertical propagation characteristics of atmospheric tides in the MLT region are addressed in the present communication. The observations revealed that the diurnal tide is more prominent than the semi/terdiurnal components over this latitude. It is also observed that the amplitudes of meridional components are stronger than that of zonal ones. The amplitude and phase structure shows the vertical propagation of diurnal tides with vertical wavelength of ~25 km. However, the vertical wavelength of the semidiurnal tide showed considerable variations. The vertical propagation characteristics of the terdiurnal tide showed some indications of their generating mechanisms. The observed features of tidal components are compared with Global Scale Wave Model (GSWM02) values and they showed a similar amplitude and phase structure for diurnal tides. Month-to-month variations in the tidal amplitudes have shown significant seasonal variation. The observed seasonal variation is discussed in light of the variation in tidal forcing and dissipation.
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Geiss, E., N. Petersen, and U. Bleil. "Amplitude variation of marine magnetic anomalies." Geologische Rundschau 78, no. 3 (October 1989): 741–52. http://dx.doi.org/10.1007/bf01829319.
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Bier, M., K. S. Kits, and J. G. Borst. "Relation between rise times and amplitudes of GABAergic postsynaptic currents." Journal of Neurophysiology 75, no. 3 (March 1, 1996): 1008–12. http://dx.doi.org/10.1152/jn.1996.75.3.1008.
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1. We recorded rise times and amplitudes of spontaneous GABAergic inhibitory postsynaptic currents (IPSCs) in melanotropes of Xenopus laevis. Average rise times did not vary with amplitude, but the rise times of larger IPSCs were less variable. A simple linear one-step Markov model for channel opening following the binding of a transmitter molecule can quantitatively account for the average rise time and its coefficient of variation as a function of amplitude. Our results indicate that the observed variations in the rise times are not due to variations in transmitter concentrations, but result from stochastic variations in the opening of the receptor channels.
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Rishbeth, H., K. J. F. Sedgemore-Schulthess, and T. Ulich. "Semiannual and annual variations in the height of the ionospheric F2-peak." Annales Geophysicae 18, no. 3 (March 31, 2000): 285–99. http://dx.doi.org/10.1007/s00585-000-0285-6.
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Abstract. Ionosonde data from sixteen stations are used to study the semiannual and annual variations in the height of the ionospheric F2-peak, hmF2. The semiannual variation, which peaks shortly after equinox, has an amplitude of about 8 km at an average level of solar activity (10.7 cm flux = 140 units), both at noon and midnight. The annual variation has an amplitude of about 11 km at northern midlatitudes, peaking in early summer; and is larger at southern stations, where it peaks in late summer. Both annual and semiannual amplitudes increase with increasing solar activity by day, but not at night. The semiannual variation in hmF2 is unrelated to the semiannual variation of the peak electron density NmF2, and is not reproduced by the CTIP and TIME-GCM computational models of the quiet-day thermosphere and ionosphere. The semiannual variation in hmF2 is approximately "isobaric", in that its amplitude corresponds quite well to the semiannual variation in the height of fixed pressure-levels in the thermosphere, as represented by the MSIS empirical model. The annual variation is not "isobaric". The annual mean of hmF2 increases with solar 10.7 cm flux, both by night and by day, on average by about 0.45 km/flux unit, rather smaller than the corresponding increase of height of constant pressure-levels in the MSIS model. The discrepancy may be due to solar-cycle variations of thermospheric winds. Although geomagnetic activity, which affects thermospheric density and temperature and therefore hmF2 also, is greatest at the equinoxes, this seems to account for less than half the semiannual variation of hmF2. The rest may be due to a semiannual variation of tidal and wave energy transmitted to the thermosphere from lower levels in the atmosphere.Key words: Atmospheric composition and structure (thermosphere - composition and chemistry) - Ionosphere (mid-latitude ionosphere)
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Stening, R. J., and C. Jacobi. "Lunar tidal winds in the upper atmosphere over Collm." Annales Geophysicae 18, no. 12 (December 31, 2000): 1645–50. http://dx.doi.org/10.1007/s00585-001-1645-6.
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Abstract. The lunar semidiurnal tide in winds measured at around 90 km altitude has been isolated with amplitudes observed up to 4 m s–1. There is a marked amplitude maximum in October and also a considerable phase variation with season. The average variation of phase with height indicated a vertical wavelength of more than 80 km but this, and other results, needs to be viewed in the light of the considerable averaging required to obtain statistical significance. Large year-to-year variations in both amplitude and phase were also found. Some phase comparisons with the GSWM model gave reasonable agreement but the model amplitudes above a height of 100 km were much larger than those measured. An attempt to make a comparison with the lunar geomagnetic tide did not yield a statistically significant result. Key words: Meteorology and atmospheric dynamics (middle atmosphere dynamics; waves and tides)
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Krebs, Charles J., John Bryant, Knut Kielland, Mark O’Donoghue, Frank Doyle, Suzanne Carriere, Donna DiFolco, et al. "What factors determine cyclic amplitude in the snowshoe hare (Lepus americanus) cycle?" Canadian Journal of Zoology 92, no. 12 (December 2014): 1039–48. http://dx.doi.org/10.1139/cjz-2014-0159.
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Snowshoe hares (Lepus americanus Erxleben, 1777) fluctuate in 9–10 year cycles throughout much of their North American range. These cycles show large variations in cyclic amplitude and we ask what factors could cause amplitude variation. We gathered data from 1976 to 2012 on hare numbers in the boreal forest of Alaska, Yukon, Northwest Territories, and northern British Columbia to describe the amplitude of hare fluctuations and to evaluate four possible causes. First, weather could cause variation in amplitude via hare reproduction or survival, but this mechanism does not fit our data. Second, bottom-up processes involving forest succession could explain amplitude variation through changes in winter forage availability, but succession is too slow a variable in our study areas. Third, plant defenses entrained by hare over-browsing in one cycle can produce variation in plant quality and quantity in subsequent cycles. A mathematical model suggests this is a possible explanation. Fourth, predator recovery following the cyclic low is inversely related to hare cyclic amplitude, and the existing data are consistent with this mechanism. A standardized regional monitoring program is needed to improve our understanding of cyclic amplitude variation in hares and the possible role of predators and winter foods in affecting amplitude.
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Bokka, Venkat, Abhishek Dey, and Shaunak Sen. "Period–amplitude co-variation in biomolecular oscillators." IET Systems Biology 12, no. 4 (August 1, 2018): 190–98. http://dx.doi.org/10.1049/iet-syb.2018.0015.
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Panaretos, Victor M., and Yoav Zemel. "Amplitude and phase variation of point processes." Annals of Statistics 44, no. 2 (April 2016): 771–812. http://dx.doi.org/10.1214/15-aos1387.
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Neidell, Norman S. "Research elements in amplitude variation with offset." Leading Edge 5, no. 4 (April 1986): 42–44. http://dx.doi.org/10.1190/1.1439257.
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Zong, Zhaoyun, Kun Li, Xingyao Yin, Ming Zhu, Jiayuan Du, Weitao Chen, and Weiwei Zhang. "Broadband seismic amplitude variation with offset inversion." GEOPHYSICS 82, no. 3 (May 1, 2017): M43—M53. http://dx.doi.org/10.1190/geo2016-0306.1.
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Seismic amplitude variation with offset (AVO) inversion is well-known as a popular and pragmatic tool used for the prediction of elastic parameters in the geosciences. Low frequencies missing from conventional seismic data are conventionally recovered from other geophysical information, such as well-log data, for estimating the absolute rock properties, which results in biased inversion results in cases of complex heterogeneous geologic targets or plays with sparse well-log data, such as marine or deep stratum. Broadband seismic data bring new opportunities to estimate the low-frequency components of the elastic parameters without well-log data. We have developed a novel AVO inversion approach with the Bayesian inference for broadband seismic data. The low-frequency components of the elastic parameters are initially estimated with the proposed broadband AVO inversion approach with the Bayesian inference in the complex frequency domain because seismic inversion in the complex frequency domain is helpful to recover the long-wavelength structures of the elastic models. Gaussian and Cauchy probability distribution density functions are used for the likelihood function and the prior information of model parameters, respectively. The maximum a posteriori probability solution is resolved to estimate the low-frequency components of the elastic parameters in the complex frequency domain. Furthermore, with those low-frequency components as initial models and constraints, the conventional AVO inversion method with the Bayesian inference in the time domain is further implemented to estimate the final absolute elastic parameters. Synthetic and field data examples demonstrate that the proposed AVO inversion in the complex frequency domain is able to predict the low-frequency components of elastic parameters well, and that those low-frequency components set a good foundation for the final estimation of the absolute elastic parameters.
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Ball, Vaughn, Luis Tenorio, Christian Schiøtt, Michelle Thomas, and J. P. Blangy. "Three-term amplitude-variation-with-offset projections." GEOPHYSICS 83, no. 5 (September 1, 2018): N51—N65. http://dx.doi.org/10.1190/geo2017-0763.1.
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A three-term (3T) amplitude-variation-with-offset projection is a weighted sum of three elastic reflectivities. Parameterization of the weighting coefficients requires two angle parameters, which we denote by the pair [Formula: see text]. Visualization of this pair is accomplished using a globe-like cartographic representation, in which longitude is [Formula: see text], and latitude is [Formula: see text]. Although the formal extension of existing two-term (2T) projection methods to 3T methods is trivial, practical implementation requires a more comprehensive inversion framework than is required in 2T projections. We distinguish between projections of true elastic reflectivities computed from well logs and reflectivities estimated from seismic data. When elastic reflectivities are computed from well logs, their projection relationships are straightforward, and they are given in a form that depends only on elastic properties. In contrast, projection relationships between reflectivities estimated from seismic may also depend on the maximum angle of incidence and the specific reflectivity inversion method used. Such complications related to projections of seismic-estimated elastic reflectivities are systematized in a 3T projection framework by choosing an unbiased reflectivity triplet as the projection basis. Other biased inversion estimates are then given exactly as 3T projections of the unbiased basis. The 3T projections of elastic reflectivities are connected to Bayesian inversion of other subsurface properties through the statistical notion of Bayesian sufficiency. The triplet of basis reflectivities is computed so that it is Bayes sufficient for all rock properties in the hierarchical seismic rock-physics model; that is, the projection basis contains all information about rock properties that is contained in the original seismic.
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Wang, Daosheng, Haidong Pan, Guangzhen Jin, and Xianqing Lv. "Seasonal variation of the principal tidal constituents in the Bohai Sea." Ocean Science 16, no. 1 (January 6, 2020): 1–14. http://dx.doi.org/10.5194/os-16-1-2020.
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Abstract. The seasonal variation of tides plays a significant role in water level changes in coastal regions. In this study, seasonal variations of four principal tidal constituents, M2, S2, K1, and O1, in the Bohai Sea, China, were studied by applying an enhanced harmonic analysis method to two time series: 1-year sea level observations at a mooring station (named E2) located in the western Bohai Sea and 17-year sea level observations at Dalian. At E2, the M2 amplitude and phase lag have annual frequencies, with large values in summer and small values in winter, while the frequencies of S2 and K1 amplitudes are also nearly annual. In contrast, the O1 amplitude increases constantly from winter to autumn. The maxima of phase lags appear twice in 1 year for S2, K1, and O1, taking place near winter and summer. The seasonal variation trends estimated by the enhanced harmonic analysis at Dalian are different from those at E2, except for the M2 phase lag. The M2 and S2 amplitudes show semi-annual and annual cycles, respectively, which are relatively significant at Dalian. The results of numerical experiments indicate that the seasonality of vertical eddy viscosity induces seasonal variations of the principal tidal constituents at E2. However, the tested mechanisms, including seasonally varying stratification, vertical eddy viscosity, and mean sea level, do not adequately explain the observed seasonal variations of tidal constituents at Dalian.
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Le Mouël, J. L., E. Blanter, and M. Shnirman. "The six-month line in geomagnetic long series." Annales Geophysicae 22, no. 3 (March 19, 2004): 985–92. http://dx.doi.org/10.5194/angeo-22-985-2004.
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Abstract. Daily means of the horizontal components X (north) and Y (east) of the geomagnetic field are available in the form of long series (several tens of years). Nine observatories are used in the present study, whose series are among the longest. The amplitudes of the 6-month and 1-year periodic variations are estimated using a simple but original technique. A remarkably clear result emerges from the complexity of the geomagnetic data: the amplitude of the 6-month line presents, in all observatories, the same large variation (by a factor of 1.7) over the 1920–1990 time span, regular and quasi-sinusoidal. Nothing comparable comes out for the annual line. The 6-month line results from the modulation by an astronomical mechanism of a magnetospheric system of currents. As this latter mechanism is time invariant, the intensity of the system of currents itself must present the large variation observed on the 6-months variation amplitude. This variation presents some similarities with the one displayed by recent curves of reconstructed solar irradiance or the "Earth's temperature". Finally, the same analysis is applied to the aa magnetic index.Key words. Geomagnetism and paleomagnetism (time variations, diurnal to secular). Magnetospheric physics (current systems; polar cap phenomena)
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Weng, Libin, Jiuhou Lei, Eelco Doornbos, Hanxian Fang, and Xiankang Dou. "Seasonal variations of thermospheric mass density at dawn/dusk from GOCE observations." Annales Geophysicae 36, no. 2 (March 22, 2018): 489–96. http://dx.doi.org/10.5194/angeo-36-489-2018.
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Abstract. Thermospheric mass densities from the GOCE (Gravity field and steady-state Ocean Circulation Explorer) satellite for Sun-synchronous orbits between 83.5∘ S and 83.5∘ N, normalized to 270 km during 2009–2013, have been used to develop an empirical mass density model at dawn/dusk local solar time (LST) sectors based on the empirical orthogonal function (EOF) method. The main results of this study are that (1) the dawn densities peak in the polar regions, but the dusk densities maximize in the equatorial regions; (2) the relative seasonal variations to the annual mean have similar patterns across all latitudes regardless of solar activity conditions; (3) the seasonal density variations show obvious hemispheric asymmetry, with large amplitudes in the Southern Hemisphere; (4) both amplitude and phase of the seasonal variations have strong latitudinal and solar activity dependences, with high amplitude for the annual variation at higher latitudes and semiannual variation at lower latitudes; (5) the annual asymmetry and effect of the Sun–Earth distance vary with latitude and solar activity. Keywords. Atmospheric composition and structure (pressure, density, and temperature)
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Stovas, Alexey. "Geometric spreading in orthorhombic media." GEOPHYSICS 83, no. 1 (January 1, 2018): C61—C73. http://dx.doi.org/10.1190/geo2016-0710.1.
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Geometric spreading is an important factor that needs to be taken into account in the analysis of seismic amplitudes. In particular, when using any modification of amplitude variation with offset or amplitude versus azimuth methods, the effect of geometric spreading is crucial to isolate the effect of reflection from a particular interface. The relative geometric spreading controls the amplitude of seismic waves passing through a velocity model. In the case of an anisotropic medium, geometric spreading becomes very complicated. Usually, geometric spreading is computed from ray tracing. I have derived simple analytical formulas to compute the relative geometric spreading of P-waves in a stack of acoustic orthorhombic layers with azimuthal variations in symmetry planes. I also analyzed the kinematic properties of the derived equations and performed sensitivity analysis with respect to three anelliptic parameters. A simple and accurate approximation for the relative geometric spreading is derived and tested against well-known approximation. My approximations give insight into the role that anelliptic parameters play into the azimuthal distribution of amplitudes and can be used for amplitude analysis in multilayered orthorhombic models.
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Javaraiah, J. "22-Year Periodicity in the Solar Differential Rotation." International Astronomical Union Colloquium 179 (2000): 167–70. http://dx.doi.org/10.1017/s0252921100064423.
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AbstractUsing the data on sunspot groups compiled during 1879–1975, we determined variations in the differential rotation coefficientsAandBduring the solar cycle. The variation in the equatorial rotation rateAis found to be significant only in the odd numbered cycles, with an amplitude ∼ 0.01μrads−1. There exists a good anticorrelation between the variations of the differential rotation rateBderived from the odd and even numbered cycles, suggesting existence of a ‘22-year’ periodicity inB. The amplitude of the variation ofBis ∼ 0.05μrads−1.
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Bruyn, John R. de, and David A. Balzarini. "Quantum effects near the liquid–vapour critical point." Canadian Journal of Physics 68, no. 4-5 (April 1, 1990): 449–53. http://dx.doi.org/10.1139/p90-069.
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We gather together a number of recent measurements of the coexistence curve and compressibility of fluids close to the critical point, and investigate the variation of the critical exponents and amplitudes as quantum effects become more important. We find that the universal critical exponents and amplitude ratios are the same for quantum fluids as for room-temperature fluids, as expected. Some of the nonuniversal critical amplitudes, however, show systematic variations as quantum effects become significant, in at least qualitative agreement with theoretical predictions.
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Palmer, Derecke. "Imaging refractors with the convolution section." GEOPHYSICS 66, no. 5 (September 2001): 1582–89. http://dx.doi.org/10.1190/1.1487103.
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Seismic refraction data are characterized by large moveouts between adjacent traces and large amplitude variations across the refraction spread. The moveouts are the result of the predominantly horizontally traveling trajectories of refraction signals, whereas the amplitude variations are the result of the rapid geometric spreading factor, which is at least the reciprocal of the distance squared. The large range of refraction amplitudes produces considerable variation in signal‐to‐noise (S/N) ratios. Inversion methods which use traveltimes only, employ data with a wide range of accuracies, which are related to the variations in the S/N ratios. The time section, generated by convolving forward and reverse seismic traces, addresses both issues of large moveouts and large amplitude variations. The addition of the phase spectra with convolution effectively adds the forward and reverse traveltimes. The convolution section shows the structural features of the refractor, without the moveouts related to the source‐to‐detector distances. Unlike the application of a linear moveout correction or reduction, a measure of the refractor wavespeed is not required beforehand. The multiplication of the amplitude spectra with convolution, compensates for the effects of geometric spreading and dipping interfaces to a good first approximation, and it is sufficient to facilitate recognition of amplitude variations related to geologic causes. These amplitude effects are not as easily recognized in the shot records. The convolution section can be generated very rapidly from shot records without a detailed knowledge of the wavespeeds in either the refractor or the overburden.
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Saar, Steven H., Michelle Dyke, Søren Meibom, and Sydney A. Barnes. "The dependence of maximum starspot amplitude and the amplitude distribution on stellar properties." Proceedings of the International Astronomical Union 6, S273 (August 2010): 469–73. http://dx.doi.org/10.1017/s1743921311015791.
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AbstractWe combine photometric data from field stars, plus over a dozen open clusters and associations, to explore how the maximum photometric amplitude (Amax) and the distribution of amplitudes varies with stellar properties. We find a complex variation of Amax with inverse Rossby number Ro−1, which nevertheless can be modeled well with a simple model including an increase in Amax with rotation for low Ro−1, and a maximum level. Amax may then be further affected by differential rotation and a decline at the highest Ro−1. The distribution of Aspot below Amax varies with Ro−1 : it peaks at low Aspot with a long tail towards Amax for low Ro−1, but is more uniformly distributed at higher Ro−1. We investigate further dependences of the Aspot distributions on stellar properties, and speculate on the source of these variations.
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Mahmoudian, Faranak, Gary F. Margrave, Joe Wong, and David C. Henley. "Azimuthal amplitude variation with offset analysis of physical modeling data acquired over an azimuthally anisotropic medium." GEOPHYSICS 80, no. 1 (January 1, 2015): C21—C35. http://dx.doi.org/10.1190/geo2014-0070.1.
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We evaluated a quantitative amplitude analysis of 3D physical model reflection data acquired over an experimental phenolic layer that modeled a fractured medium with one set of vertical fractures. The phenolic layer was overlain by two isotropic layers, the uppermost being water, and the data acquisition was designed to avoid the interference of the primary and ghost events. The elastic stiffness coefficients and hence the anisotropy of the phenolic layer were known in advance from a previous traveltime analysis. The reflection amplitudes from the top of the phenolic layer required corrections to make them suitable for an amplitude study. In addition to the usual amplitude corrections applied to seismic field data, a directivity correction specific to the physical model transducers was applied. The corrected amplitudes along different azimuths showed a clear azimuthal variation caused by the phenolic layer and agreed with amplitudes predicted theoretically. An amplitude variation with angle and azimuth inversion was performed for horizontal transverse isotropy (HTI) parameters of the phenolic layer. We determined from the inversion results that from the azimuthally varying P-wave reflectivity response, it was possible to estimate HTI parameters that compared favorably to those obtained previously by a traveltime analysis. This result made it possible to compute the S-wave splitting parameter [Formula: see text] (historically determined from S-wave data and directly related to fracture density) from a quantitative analysis of the PP data.
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Lan, Wen-Hau, Chung-Yen Kuo, Li-Ching Lin, and Huan-Chin Kao. "Annual Sea Level Amplitude Analysis over the North Pacific Ocean Coast by Ensemble Empirical Mode Decomposition Method." Remote Sensing 13, no. 4 (February 17, 2021): 730. http://dx.doi.org/10.3390/rs13040730.
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Understanding spatial and temporal changes of seasonal sea level cycles is important because of direct influence on coastal systems. The annual sea level cycle is substantially larger than semi-annual cycle in most parts of the ocean. Ensemble empirical mode decomposition (EEMD) method has been widely used to study tidal component, long-term sea level rise, and decadal sea level variation. In this work, EEMD is used to analyze the observed monthly sea level anomalies and detect annual cycle characteristics. Considering that the variations of the annual sea level variation in the Northeast Pacific Ocean are poorly studied, the trend and characteristics of annual sea level amplitudes and related mechanisms in the North Pacific Ocean are investigated using long-term tide gauge records covering 1950–2016. The average annual amplitude of coastal sea level exhibits interannual-to-decadal variability within the range of 14–220 mm. The largest value of ~174 mm is observed in the west coast of South China Sea. In the other coastal regions of North Pacific Ocean, the mean annual amplitude is relatively low between 77 and 124 mm for the western coast and 84 and 87 mm for the eastern coast. The estimated trend values for annual sea level amplitudes in the western coastal areas of South China Sea and Northeast Pacific Ocean have statistically decreased over 1952–2014 with a range of −0.77 mm·yr−1 to −0.11 mm·yr−1. Our results suggested that the decreasing annual amplitude in the west coast of South China Sea is in good agreement with the annual mean wind stress associated with the Pacific Decadal Oscillation (PDO). This wind phenomenon also explains the temporal variations of annual sea level amplitude in Northeast Pacific Ocean, especially the high correlations since 1980 (R = 0.61−0.72).
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Orlikoff, Robert F. "Vowel amplitude variation associated with the heart cycle." Journal of the Acoustical Society of America 88, no. 5 (November 1990): 2091–98. http://dx.doi.org/10.1121/1.400106.
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Marron, J. S., James O. Ramsay, Laura M. Sangalli, and Anuj Srivastava. "Functional Data Analysis of Amplitude and Phase Variation." Statistical Science 30, no. 4 (November 2015): 468–84. http://dx.doi.org/10.1214/15-sts524.
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Bharadwaj, Shrikant R., M. Pia Hoenig, Viswanathan C. Sivaramakrishnan, Baskaran Karthikeyan, Donna Simonian, Katie Mau, Sally Rastani, and Clifton M. Schor. "Variation of Binocular-Vertical Fusion Amplitude with Convergence." Investigative Opthalmology & Visual Science 48, no. 4 (April 1, 2007): 1592. http://dx.doi.org/10.1167/iovs.06-1018.
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De Abreu, Elita Selmara, John Patrick Castagna, and Gabriel Gil. "Case study: Phase-component amplitude variation with angle." GEOPHYSICS 84, no. 4 (July 1, 2019): B285—B297. http://dx.doi.org/10.1190/geo2018-0762.1.
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In detectable and isolated thin layers below seismic resolution, phase decomposition can theoretically be used to discriminate relatively high-impedance thin-layer responses from low-impedance reservoir responses. Phase decomposition can be used to isolate seismic amplitudes with a particular phase response or to decompose the seismic trace into symmetrical and antisymmetrical phase components. These components sum to form the original trace. Assuming zero-phase seismic data and normal American polarity, seismically thin layers that are high impedance relative to overlying and underlying half-spaces are seen on the [Formula: see text] phase component, whereas a relatively low-impedance thin layer will appear on the [Formula: see text] phase component. When such phase decomposition is applied to prestack attributes on a 2D line across a thin, 8 m thick, gas-saturated reservoir in the Western Canadian Sedimentary Basin of Alberta, Canada, amplitude-variation-with-angle is magnified on the [Formula: see text] phase component. The [Formula: see text] far-offset component allows the lateral extent of the reservoir to be better delineated. This amplification is also seen on the [Formula: see text] phase component of the gradient attribute. These results are corroborated by seismic modeling that indicates the same phase-component relationships for near- and far-angle stacks as are observed on the real data. Fluid substitution and seismic modeling indicate that, relative to full-phase data, the mixed-phase response observed in this study exhibits variations in fluid effects that are magnified and better observed at far angles on the [Formula: see text] phase component.
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Sarkar, Debashish, Robert T. Baumel, and Ken L. Larner. "Velocity analysis in the presence of amplitude variation." GEOPHYSICS 67, no. 5 (September 2002): 1664–72. http://dx.doi.org/10.1190/1.1512814.
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Conventional semblance velocity analysis is equivalent to modeling prestack seismic data with events that have hyperbolic moveout but no amplitude variation with offset (AVO). As a result of its assumption that amplitude is independent of offset, this method might be expected to perform poorly for events with strong AVO—especially for events with polarity reversals at large offset, such as reflections from tops of some class 1 and class 2 sands. We find that substantial amplitude variation and even phase change with offset do not compromise the conventional semblance measure greatly. Polarity reversal, however, causes conventional semblance to fail. The semblance method can be extended to take into account data with events that have amplitude variation, expressed by AVO intercept and gradient (i.e., the Shuey approximation). However, because of the extra degrees of freedom introduced in AVO‐sensitive semblance, resolution of the estimated velocities is decreased. This is because the data can be modeled acceptably with a range of combined erroneous velocity and AVO behavior. To address this problem, in addition to using the Shuey equation to describe the amplitude variation, we constrain the AVO parameters (intercept and gradient) to be related linearly within each semblance window. With this constraint we can preserve velocity resolution and improve the quality of velocity analysis in the presence of amplitude and even polarity variation with offset. Results from numerical tests suggest that the modified semblance is accurate in the presence of polarity reversals. Tests also indicate, however, that in the presence of noise, the signal peak in conventional semblance has better standout than does that in the modified semblance measures.
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Wilson, Hamish, and Lutz Gross. "Amplitude variation with offset-friendly bootstrapped differential semblance." GEOPHYSICS 82, no. 5 (September 1, 2017): V297—V309. http://dx.doi.org/10.1190/geo2016-0395.1.
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Spectral noise, low resolution, and attenuation of semblance peaks due to amplitude variation with offset (AVO) anomalies hamper the reliability of velocity analysis in the semblance spectrum for seismic data processing. Increasing resolution and reducing noise while accounting for AVO has posed a challenge in various semblance schemes due to a trade-off in resolution and AVO detectability. A new semblance scheme is introduced that aims to remove this trade-off. The new scheme uses the concepts of bootstrapped differential semblance with trend-based AB semblance. Results indicate that the new scheme indeed increases spectral resolution, reduces noise, and accounts for AVO anomalies. These improvements facilitate velocity control for automatic and manual picking methods and, hence, provide a means for more reliable apparent velocity models.
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Chen, W. Y., C. W. Lovell, G. M. Haley, and L. J. Pyrak-Nolte. "Variation of shear-wave amplitude during frictional sliding." International Journal of Rock Mechanics and Mining Sciences & Geomechanics Abstracts 30, no. 7 (December 1993): 779–84. http://dx.doi.org/10.1016/0148-9062(93)90022-6.
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Vivas, Flor A., and Reynam C. Pestana. "True-amplitude one-way wave equation migration in the mixed domain." GEOPHYSICS 75, no. 5 (September 2010): S199—S209. http://dx.doi.org/10.1190/1.3478574.
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One-way wave equation migration is a powerful imaging tool for locating accurately reflectors in complex geologic structures; however, the classical formulation of one-way wave equations does not provide accurate amplitudes for the reflectors. When dynamic information is required after migration, such as studies for amplitude variation with angle or when the correct amplitudes of the reflectors in the zero-offset images are needed, some modifications to the one-way wave equations are required. The new equations, which are called “true-amplitude one-way wave equations,” provide amplitudes that are equivalent to those provided by the leading order of the ray-theoretical approximation through the modification of the transverse Laplacian operator with dependence of lateral velocity variations, the introduction of a new term associated with the amplitudes, and the modification of the source representation. In a smoothly varying vertical medium,the extrapolation of the wavefields with the true-amplitude one-way wave equations simplifies to the product of two separable and commutative factors: one associated with the phase and equal to the phase-shift migration conventional and the other associated with the amplitude. To take advantage of this true-amplitude phase-shift migration, we developed the extension of conventional migration algorithms in a mixed domain, such as phase shift plus interpolation, split step, and Fourier finite difference. Two-dimensional numerical experiments that used a single-shot data set showed that the proposed mixed-domain true-amplitude algorithms combined with a deconvolution-type imaging condition recover the amplitudes of the reflectors better than conventional mixed-domain algorithms. Numerical experiments with multiple-shot Marmousi data showed improvement in the amplitudes of the deepest structures and preservation of higher frequency content in the migrated images.
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Worthington, R. M. "Diurnal variation of mountain waves." Annales Geophysicae 24, no. 11 (November 21, 2006): 2891–900. http://dx.doi.org/10.5194/angeo-24-2891-2006.
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Abstract. Mountain waves could be modified as the boundary layer varies between stable and convective. However case studies show mountain waves day and night, and above e.g. convective rolls with precipitation lines over mountains. VHF radar measurements of vertical wind (1990–2006) confirm a seasonal variation of mountain-wave amplitude, yet there is little diurnal variation of amplitude. Mountain-wave azimuth shows possible diurnal variation compared to wind rotation across the boundary layer.
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Zhu, C., and H. Yoshikawa-Inoue. "Temporal variations in atmospheric CO<sub>2</sub> on Rishiri Island in 2006–2013: responses of the interannual variation in amplitude to climate and the terrestrial sink in East Asia." Earth System Dynamics Discussions 5, no. 1 (June 27, 2014): 809–48. http://dx.doi.org/10.5194/esdd-5-809-2014.
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Abstract. Surface observation of the atmospheric CO2 mixing ratio implies the combined influences of both natural fluctuations and anthropogenic activities on the carbon cycle. Atmospheric CO2 has been measured on Rishiri Island in the outflow region of Eurasia since May 2006. We report the first 7 year temporal atmospheric CO2 variations from diurnal to interannual scales. In the diurnal scale, an obvious cycle appeared as a minimum in the afternoon and maximum at midnight in the summer months. Seasonally, the maximum CO2 concentration appeared around the beginning of April, while the minimum appeared around the middle of August. A mean growing season length of ~126 days was estimated. In the period from 2007 to 2012, the peak-to-peak amplitude increased until 2009 and decreased thereafter, with a mean value of 19.7 ppm. In the long term, atmospheric CO2 is increasing by a mean growth rate of 2.1 ppm year−1. Investigations on the driving climatic factors on the interannual variation in amplitude indicated that temperature in East Asia (40–60° N, 90–150° E) affected the CO2 amplitude by affecting the seasonal maximum, with a time lag of 1–2 years. On the contrary, precipitation did not likely affect CO2 amplitudes. The amplitude also responded to a natural carbon source/sink variation in East Asia. We suggest that temperature in the first year would affect carbon sinks in the second year in the fetch regions, which further affect CO2 amplitude mainly through ecosystem respiration. Circulation changes also likely contributed to the decreasing amplitude since 2009, as indicated by the simultaneous decrease in the 222Rn concentration in spring and summer.
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Widyantoro, Adi, and Matthew Saul. "Shaly sand rock physics analysis and seismic inversion implication." APPEA Journal 54, no. 2 (2014): 503. http://dx.doi.org/10.1071/aj13076.
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The analysis of well data from the Enfield field of the Exmouth Sub-basin, WA, indicates that both cementation and pore-filling clay appear to have a stiffening effect on the reservoir sands. The elastic contrast between brine sand and the overlying shale is often small and the large amplitudes observed from seismic data are associated with hydrocarbon content. More detailed rock physics and depth trend analysis of elastic and petrophysical properties, however, indicate significant spatial variability in the cap rock shales across the field with different sand shale mixtures, causing changes in the elastic response of the rock. Areas where shales are softer produce weak seismic amplitude contrasts even with high hydrocarbon saturation; the amplitude response being similar to areas with stiffer shales and brine-filled sands. The variations in reservoir quality are, therefore, masked by the distribution of the brine, oil and gas, as well as the variations in the cap rock. The Enfield rock physics analysis provides an example of reducing amplitude ambiguity over lithology-fluid variation and improves the chance of successful interpretation of the results of seismic inversion.
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Frerking, Matthew, Salvador Borges, and Martin Wilson. "Variation in GABA mini amplitude is the consequence of variation in transmitter concentration." Neuron 15, no. 4 (October 1995): 885–95. http://dx.doi.org/10.1016/0896-6273(95)90179-5.
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Vieira, Taian M., Alberto Botter, Marco A. Minetto, and Emma F. Hodson-Tole. "Spatial variation of compound muscle action potentials across human gastrocnemius medialis." Journal of Neurophysiology 114, no. 3 (September 2015): 1617–27. http://dx.doi.org/10.1152/jn.00221.2015.
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The massed action potential (M wave) elicited through nerve stimulation underpins a wide range of physiological and mechanical understanding of skeletal muscle structure and function. Although systematic approaches have evaluated the effect of different factors on M waves, the effect of the location and distribution of activated fibers within the muscle remains unknown. By detecting M waves from the medial gastrocnemius (MG) of 12 participants with a grid of 128 electrodes, we investigated whether different populations of muscle units have different spatial organization within MG. If populations of muscle units occupy discrete MG regions, current pulses of progressively greater intensities applied to the MG nerve branch would be expected to lead to local changes in M-wave amplitudes. Electrical pulses were therefore delivered at 2 pps, with the current pulse amplitude increased every 10 stimuli to elicit different degrees of muscle activation. The localization of MG response to increases in current intensity was determined from the spatial distribution of M-wave amplitude. Key results revealed that increases in M-wave amplitude were detected somewhat locally, by 10–50% of the 128 electrodes. Most importantly, the electrodes detecting greatest increases in M-wave amplitude were localized at different regions in the grid, with a tendency for greater stimulation intensities to elicit M waves in the more distal MG region. The presented results indicate that M waves recorded locally may not provide a representative MG response, with major implications for the estimation of, e.g., the maximal stimulation levels, the number of motor units, and the onset and normalization in H-reflex studies.
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Zhang, Kanghe, Li Chen, Yuchen Li, Bowen Yu, and Yule Wang. "Experimental Study on the Influence of the Transition Section in the Middle of a Continuous Bend on the Correlation of Flow Movement in the Front and Back Bends." Water 12, no. 11 (November 17, 2020): 3213. http://dx.doi.org/10.3390/w12113213.
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There exists a correlation in the flow movement between the front and back bends of a continuous bend, and the change in the transition section configuration influences this correlation. In this paper, laboratory experiments were conducted to systematically measure the three-dimensional velocity in a continuous bend with different width/depth ratios of the transition section. Based on this work, the flow movement characteristics of a continuous bend were analysed, including the circulation structure, circulation intensity and Turbulent Kinetic Energy (TKE). The flow movement correlation between the front and back bends of the continuous bend was also analysed. The influence of the width/depth ratio of the transition section on the correlation of the flow movement of the front and back bends and their relationship with discharge were explored. This research could help to elucidate the development and evolution laws of the continuous bend and provide theoretical support for flow movement, flood routing, sediment transport and riverbed evolution. It is found that in addition to the circulation structure and intensity, the TKE of the front and back bends of the continuous bend also shows a strong correlation. With increasing discharge, the correlation between the front and back bends increases, and the larger the discharge is, the greater the influence of the same amplitude of variation in the discharge on the correlation. At the same time, the larger the discharge is, the greater the influence of the same amplitude of variation in the width/depth ratio of the transition section on the correlation of the front and back bends. When the discharge is constant, the correlation between the front and back bends decreases with the decrease in the width/depth ratio of the transition section, and the smaller the width/depth ratio, the greater the influence of the same amplitude of variation in the width/depth ratio on the correlation. There is no linear relationship between the amplitudes of variation in both the discharge and width/depth ratio and the corresponding amplitude of variation in the correlation. With increasing discharge, the amplitude of variation in the correlation caused by the same amplitude of the variation in discharge slightly increases. However, there is an exponential relationship between the amplitude of variation in the width/depth ratio and the corresponding correlation. The influence of the width/depth ratio on the correlation is clearly greater than that of the discharge.
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Seguy, Sébastien, Gilles Dessein, Lionel Arnaud, and Tamás Insperger. "Control of Chatter by Spindle Speed Variation in High-Speed Milling." Advanced Materials Research 112 (May 2010): 179–86. http://dx.doi.org/10.4028/www.scientific.net/amr.112.179.
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High-speed milling operations are often limited by regenerative vibrations. The aim of this paper is to analyze the effect of spindle speed variation on machine tool chatter in high-speed milling. The stability analysis of triangular and sinusoidal shape variations is made numerically with the semi-discretization method. Parametric studies show also the influence of the frequency and amplitude variation parameters. This modeling is validated experimentally by variable spindle speed cutting tests with a triangular shape. Stable and unstable tests are analyzed in term of amplitude vibration and surface roughness degradation. This work reveals that stability must be considered at period variation scale. It is also shown that spindle speed variation can be efficiently used to suppress chatter in the flip lobe area.
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Contreras, Bret, Andrew D. Vigotsky, Brad J. Schoenfeld, Chris Beardsley, and John Cronin. "A Comparison of Gluteus Maximus, Biceps Femoris, and Vastus Lateralis Electromyography Amplitude for the Barbell, Band, and American Hip Thrust Variations." Journal of Applied Biomechanics 32, no. 3 (June 2016): 254–60. http://dx.doi.org/10.1123/jab.2015-0091.
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Bridging exercise variations are well researched and commonly employed for both rehabilitation and sport performance. However, resisted bridge exercise variations have not yet been compared in a controlled experimental study. Therefore, the purpose of this study was to compare the differences in upper and lower gluteus maximus, biceps femoris, and vastus lateralis electromyography (EMG) amplitude for the barbell, band, and American hip thrust variations. Thirteen healthy female subjects (age = 28.9 y; height = 164.3 cm; body mass = 58.2 kg) familiar with the hip thrust performed 10 repetitions of their 10-repetition maximum of each variation in a counterbalanced and randomized order. The barbell hip thrust variation elicited statistically greater mean gluteus maximus EMG amplitude than the American and band hip thrusts, and statistically greater peak gluteus maximus EMG amplitude than the band hip thrust (P ≤ .05), but no other statistical differences were observed. It is recommended that resisted bridging exercise be prescribed according to the individual’s preferences and desired outcomes.
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Ghosh, S. S., and G. S. Lakhina. "Anomalous width variation of rarefactive ion acoustic solitary waves in the context of auroral plasmas." Nonlinear Processes in Geophysics 11, no. 2 (April 14, 2004): 219–28. http://dx.doi.org/10.5194/npg-11-219-2004.
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Abstract. The presence of dynamic, large amplitude solitary waves in the auroral regions of space is well known. Since their velocities are of the order of the ion acoustic speed, they may well be considered as being generated from the nonlinear evolution of ion acoustic waves. However, they do not show the expected width-amplitude correlation for K-dV solitons. Recent POLAR observations have actually revealed that the low altitude rarefactive ion acoustic solitary waves are associated with an increase in the width with increasing amplitude. This indicates that a weakly nonlinear theory is not appropriate to describe the solitary structures in the auroral regions. In the present work, a fully nonlinear analysis based on Sagdeev pseudopotential technique has been adopted for both parallel and oblique propagation of rarefactive solitary waves in a two electron temperature multi-ion plasma. The large amplitude solutions have consistently shown an increase in the width with increasing amplitude. The width-amplitude variation profile of obliquely propagating rarefactive solitary waves in a magnetized plasma have been compared with the recent POLAR observations. The width-amplitude variation pattern is found to fit well with the analytical results. It indicates that a fully nonlinear theory of ion acoustic solitary waves may well explain the observed anomalous width variations of large amplitude structures in the auroral region.
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Siniatchkin, M., E. Kirsch, P. Kropp, U. Stephani, and W.-D. Gerber. "Slow Cortical Potentials in Migraine Families." Cephalalgia 20, no. 10 (December 2000): 881–92. http://dx.doi.org/10.1046/j.1468-2982.2000.00132.x.
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Amplitude and habituation of event-related potentials are abnormal in migraine. We investigated 43 migraine and 41 healthy families to evaluate the influences of age, sex and familial contribution on the variance of amplitude and habituation of the contingent negative variation (CNV). Analysis of individual differences in relation to the CNV habituation was performed. The study demonstrated that habituation of the early CNV component characterizes migraine considerably better than the CNV amplitudes. Habituation, however, is strongly influenced by age. Migraine adults and children generally showed reduced habituation. Surprisingly, more than 30% of the healthy adults demonstrated a marked loss of habituation. The reduced CNV habituation represented a high sensitivity but low specificity to migraine, especially in children. CNV amplitude and habituation parameters revealed a considerable familial contribution associated with migraine. No familial influence on either morphology or habituation of the CNV in healthy families or between healthy members of migraine families was observed. The low specificity and familial transmission of CNV parameters in members of migraine families suggest that increased amplitudes and reduced habituation of CNV do not constitute a primary risk factor for migraine, but rather represent a predisposition. Genetic components probably affect variation of the CNV amplitude and habituation.
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Pararó, M., J. Pena, R. Peniche, C. Ibanoglu, Z. Tunca, and S. Evren. "Short-Term Amplitude Variation of FM Com (=HR 4684)." International Astronomical Union Colloquium 134 (1993): 185–87. http://dx.doi.org/10.1017/s0252921100014159.
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AbstractUsing unpublished data obtained in 1982 at Mexico and Turkey combined with Hungarian observations the process of amplitude variation of the frequency at 18.5 c/d is shown. The time scale of the amplitude increase is less than 100 days.
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Barlow, Christopher, Lee Davison, Ray Weinstein, and Mark Ashmore. "Amplitude variation in calibrated audiometer systems in Clinical Simulations." Noise and Health 16, no. 72 (2014): 299. http://dx.doi.org/10.4103/1463-1741.140510.
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Ohmukai, Masato, and Yasuo Tsutsumi. "Chopping Frequency Variation of Photoacoustic Amplitude from Porous Silicon." Japanese Journal of Applied Physics 39, Part 1, No. 2A (February 15, 2000): 448–49. http://dx.doi.org/10.1143/jjap.39.448.
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Alvarado Méndez, E., M. Trejo Durán, J. M. Estudillo Ayala, and R. Rojas Laguna. "Amplitude variation in fractional multiple-interference on N-beams." Acta Universitaria 23 (December 1, 2013): 36–39. http://dx.doi.org/10.15174/au.2013.582.
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Multiple periodic patterns by light interference are a complicated problem from an experimental point of view. We report a theoretical model of the incidence of N beams of light at one point in space. Two components of the electric field are projected: azimuthal (angle formed with the projection of the vector in space on the x-y plane) and zenithal (angle of the incident vector with the z-axis). As a result, azimuthal intensity and zenithal intensity are found. The case of fractional amplitude or fractional number of beams is analyzed. When the phase is modified, the process allows us to visualize the change of geometry. Quasi-lineal patterns to maximum and minimum concentric circles are observed. Some applications of these patterns can be found in sensors and engraving in some lithography processes.
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Wapenaar, Kees. "Amplitude‐variation‐with‐angle behavior of self‐similar interfaces." GEOPHYSICS 64, no. 6 (November 1999): 1928–38. http://dx.doi.org/10.1190/1.1444699.
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Amplitude‐variation‐with‐angle (AVA) analysis is generally based on the assumption that the medium parameters behave as step functions of the depth coordinate z, at least in a finite region around the interface. However, outliers observed in well logs often behave quite differently from step functions. In this paper, outliers in the acoustic propagation velocity are parameterized by functions of the form [Formula: see text]. The wavelet transform of this function reveals properties similar to those of several outliers in real well logs. Moreover, this function is self‐similar, according to [Formula: see text], for β > 0. Analytical expressions are derived for the acoustic normal incidence reflection and transmission coefficients for this type of velocity function. For oblique incidence, no explicit solutions are available. However, by exploiting the self‐similarity property of the velocity function, it turns out that the acoustic angle‐dependent and frequency‐dependent reflection and transmission coefficients are self‐similar as well. To be more specific, these coefficients appear to be constant along curves described by [Formula: see text], where p is the raypath parameter and ω the angular frequency. The singularity exponent α that is reflected in these curves may prove to be a useful indicator in seismic characterization.
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Riedel, Michael, Stan E. Dosso, and Laurens Beran. "Uncertainty estimation for amplitude variation with offset (AVO) inversion." GEOPHYSICS 68, no. 5 (September 2003): 1485–96. http://dx.doi.org/10.1190/1.1620621.
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This paper uses a Bayesian approach for inverting seismic amplitude versus offset (AVO) data to provide estimates and uncertainties of the viscoelastic physical parameters at an interface. The inversion is based on Gibbs' sampling approach to determine properties of the posterior probability distribution (PPD), such as the posterior mean, maximum a posteriori (MAP) estimate, marginal probability distributions, and covariances. The Bayesian formulation represents a fully nonlinear inversion; the results are compared to those of standard linearized inversion. The nonlinear and linearized approaches are applied to synthetic test cases which consider AVO inversion for shallow marine environments with both unconsolidated and consolidated seabeds. The result of neglecting attenuation in the seabed is investigated, and the effects of data factors such as independent and systematic errors and the range of incident angles are considered. The Bayesian approach is also applied to estimate the physical parameters and uncertainties from AVO data collected at two sites along a seismic line in the Baltic Sea with differing sediment types; it clearly identifies the distinct seabed compositions. Data uncertainties (independent and systematic) required for this analysis are estimated using a maximum‐likelihood approach.