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861.
The purpose of this study was to investigate if there was an effect of duration of speaking on determination of habitual pitch. Five speaking periods commonly used to elicit habitual pitch in clinical voice evaluations were compared (1, 5, 15, 30, and 60 seconds). Thirty female speakers with normal voices participated. Results of a within-subject univariate F-test revealed a statistically significant (p < 0.001) difference in habitual pitch among the speaking periods. Habitual pitch for the 1-second and 60-second speaking periods were found to be statistically significantly (p < 0.05) different than all remaining speaking periods, and the habitual pitch for the 30-second speaking period was found to be statistically significantly (p < 0.05) different than 60-second speaking period. Implications for the use of various speaking durations when determining habitual pitch are discussed, as is the possibility of a speaking duration effect on determination of other pitch-related voice parameters. 相似文献
862.
C.F. Lo 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1998,1(1):93-95
Based upon the hidden Lie SU(1,1) symmetry, we have constructed the unitary decoupling transformation which diagonalizes the
multimode two-quantum Jaynes-Cummings model and provides us with an extremely convenient basis to gain a deeper understanding
of the dressing processes present in the matter-field interaction. This canonical transformation approach is very simple and
can be easily extended to other generalized Jaynes-Cummings models.
Received: 5 July 1997 / Revised: 3 November 1997 / Accepted: 14 November 1997 相似文献
863.
Summary It is shown that in the presence of a crossed electric and magnetic field the electronic states of a semiconductor in the
effective-mass approximation are described by a Hamiltonian containing a non-local potential. In order to preserve the gauge
invariance of the two-photon interband transition rate, the interaction Hamiltonian between the electrons and the incident
radiation has to be generalized. For GaAs, the transition rate between two particular levels is evaluated in both length and
velocity gauges demonstrating the correctness of our approach.
Work partially supported by the European Community Programme ESPRIT, Basic research, action n. 6878, EASI. 相似文献
864.
Rudolf Beran 《Annals of the Institute of Statistical Mathematics》1993,45(4):639-654
Linear regression models with random coefficients express the idea that each individual sampled may have a different linear response function. Technically speaking, random coefficient regression encompasses a rich variety of submodels. These include deconvolution or affine-mixture models as well as certain classical linear regression models that have heteroscedastic errors, or errors-in-variables, or random effects. This paper studies minimum distance estimates for the coefficient distributions in a general, semiparametric, random coefficient regression model. The analysis yields goodness-of-fit tests for the semiparametric model, prediction regions for future responses, and confidence regions for the distribution of the random coefficients.This research was supported in part by NSF Grant DMS 9001710. 相似文献
865.
C. Ferdeghini V. Ferrando V. Braccini M.R. Cimberle D. Marré P. Manfrinetti A. Palenzona M. Putti 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,30(2):147-151
The anisotropy of MgB2 is still under debate: its value, strongly dependent on the kind of sample and on the measuring method, ranges between 1.2
and 13. In this work we present our results on MgB2 c-oriented superconducting thin film. To evaluate the anisotropy, we followed two different approaches. Firstly, magnetoresistivity
was measured as a function of temperature at selected magnetic fields applied both parallel and perpendicular to the c-axis; secondly, we measured magnetoresistivity at selected temperatures and magnetic fields, varying the angle θ between the magnetic field and the c-axis. The anisotropy estimated from the ratio between the upper critical fields parallel and perpendicular to the c-axis and the one obtained in the framework of the scaling approach within the anisotropic Ginzburg-Landau theory are different
but show a similar trend in the temperature dependence. Some differences in the upper critical field and in its anisotropy
of our film with respect to single crystals are emphasized: some of these aspects can be accounted for by an analysis of upper
critical fields within a two-band model in presence of disorder and/or crystallographic strain.
Received 12 July 2002 / Received in final form 17 September 2002 Published online 29 November 2002 相似文献
866.
867.
On the interplay between inertial and viscoelastic effects for the flow in weakly modulated channels
The flow inside a spatially modulated channel is examined for viscoelastic fluids of the Oldroyd‐B type. The lower wall is flat and the upper wall is sinusoidally modulated. The modulation amplitude is assumed to be small. Thus, a regular perturbation expansion of the flow field coupled to a variable‐step finite‐difference scheme is used to solve the problem. Convergence and accuracy assessment against earlier experimental results indicate that there is a significant range of validity of the perturbation approach. The influences of wall geometry, inertia and viscoelasticity on the flow kinematics and stresses are investigated systematically. In particular, the interplay between the flow and fluid parameters effects on the conditions for the onset of backflow, number of vortices, their size and location is revealed. The distance between the flow separation and reattachment locations identifies the vortex size. Non‐monotonic dependence of the vortex size on elasticity is reported. The critical conditions for the onset of negative elasticity effects on vortex size are identified. The critical Reynolds number for the onset of backflow initially decreases then levels off or even increases as elasticity increases. For highly elastic fluid and large enough Reynolds number, more than one vortex appear near the lower wall. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
868.
对过氧亚硝酸的细胞生物学效应做了简单阐述,全面回顾和总结了近年来用于过氧亚硝酸测定的各种分析方法,并对各种方法的优缺点及其适用范围进行了比较.过氧亚硝酸的相关研究已取得很大进展,但其在线准确检测仍存在一定困难. 相似文献
869.
《Magnetic resonance in chemistry : MRC》2003,41(2):135-138
The proton transfer equilibrium in a series of double Schiff base derivatives of trans‐1,2‐diaminocyclohexane in solution and the solid state was studied by means of 15N NMR spectroscopy and analysis of the deuterium isotope effect on the chemical shifts Δ15N(D). The presence of a proton transfer equilibrium in the N‐2‐hydroxynaphthylidene moieties of the Schiff bases studied in the solid state at room temperature was evidenced. The results confirmed the interrelation of the two hydrogen bonds in double Schiff base derivatives of trans‐1,2‐diaminocyclohexane. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
870.
This is the first of a couple of papers in which the peculiar capabilities of the Hamiltonian approach to general relativity
are exploited to get both new results concerning specific technical issues, and new insights about old foundational problems of the theory. The first paper includes: (1) a critical analysis of the various concepts of symmetry
related to the Einstein-Hilbert Lagrangian viewpoint on the one hand, and to the Hamiltonian viewpoint, on the other. This
analysis leads, in particular, to a re-interpretation of active diffeomorphisms as passive and metric-dependent dynamical symmetries of Einstein's equations, a re-interpretation which enables to disclose the (not widely known)) connection
of a subgroup of them to Hamiltonian gauge transformations on-shell; (2) a re-visitation of the canonical reduction of the ADM formulation of general relativity, with particular emphasis on
the geometro-dynamical effects of the gauge-fixing procedure, which amounts to the definition of a global non-inertial, space-time laboratory. This analysis discloses the peculiar dynamical nature that the traditional definition of distant simultaneity and clock-synchronization assume in general relativity, as well as
the gauge relatedness of the “conventions” which generalize the classical Einstein's convention. (3) a clarification of the physical role of Dirac
and gauge variables, as their being related to tidal-like and generalized inertial effects, respectively. This clarification is mainly due to the fact that, unlike the standard formulations of the equivalence principle,
the Hamiltonian formalism allows to define a generalized notion of “force” in general relativity in a natural way. 相似文献