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51.
Meccanica - We take up the challenge to explain the correlation between the Jeans instability topic towards star formation within the accelerated expansion of universe and the role of torsional... 相似文献
52.
Alain Tressaud Jean Louis Soubeyroux Jean Michel Dance René Sabatier Paul Hagenmuller Barbara M. Wanklyn 《Solid State Communications》1981,37(6):479-484
The nature of the magnetic interactions in the chain compound Rb2FeF5 has been investigated using neutron diffraction and magnetic measurements under high applied fields. Rb2FeF5 orders antiferromagnetically at TN = 8.0 ± 0.5 K; the magnetic structure is of the AZ + GX mode and the moment of the Fe3+ ion extrapoled to 0K is 3.5 ± 0.2 μB, this low value being due to zero-point spin reduction. Within a chain the Fe3+ ions are antiferromagnetically coupled with an exchange constant of J/k = ?8.8 K. A spin-flop behavior has been observed and interpreted on the basis of the molecular field theory. The critical field was found to be HC = 65 kOe at 1.7 K. 相似文献
53.
Barbara Opozda 《Geometriae Dedicata》1995,55(2):141-163
We present a new approach — which is more general than the previous ones — to the affine differential geometry of complex hypersurfaces inC
n+1. Using this general approach we study some curvature conditions for induced connections.The research supported by Alexander von Humboldt Stiftung and KBN grant no. 2 P30103004. 相似文献
54.
Professional vocalists encounter demands requiring voluntary control of phonation, while utilizing a considerable range of frequency and intensity. These quantifiable acoustic events can be measured and represented in a phonetogram. Previous research has compared the phonetograms of trained and untrained voices and found significant differences between these groups. This study was designed to assess the effects of vocal training for singers over a period of nine months. Phonetogram contour changes were examined, with the primary focus on expansion of frequency range and/or intensity control. Twenty-one first-year, master's level, vocal music students, who were engaged in an intensive vocal performance curriculum, participated in this study. Following nine months of vocal training, significant differences were revealed in the subjects' mean frequency range and minimum vocal intensity across frequency levels. There was no significant difference for the mean maximum vocal intensity across frequency levels following vocal training. 相似文献
55.
Barbara Opozda 《Proceedings of the American Mathematical Society》2004,132(9):2713-2721
Global properties of locally homogeneous and curvature homogeneous affine connections are studied. It is proved that the only locally homogeneous connections on surfaces of genus different from 1 are metric connections of constant curvature. There exist nonmetrizable nonlocally symmetric locally homogeneous affine connections on the torus of genus 1. It is proved that there is no global affine immersion of the torus endowed with a nonflat locally homogeneous connection into .
56.
Ilda Abe Rafael E. de Ges Jos L. Fabris Hypolito J. Kalinowski Mrcia Müller Meire C. Fugihara Rosane Falate Barbara W. Diesel Ricardo C. Kamikawachi Carmen L. Barbosa 《Optics and Lasers in Engineering》2003,39(5-6):537-548
In this work, we report production and modelling of both Bragg gratings and rocking filters in high birefringence fibre optics. Bragg gratings are produced by UV (257.0 nm) external interferometric exposition of a frequency-doubled Ar+ ion laser, whereas for rocking filters formation the visible Ar+ ion laser lines in 488.0 and 514.5 nm are used in an internal method. The spectral characteristics due to the birefringence properties are studied through numerical methods and experimental techniques. The spectral responsivity of the structures under temperature changes and stress application is presented. 相似文献
57.
Barbara L. Osofsky 《代数通讯》2013,41(7):2071-2080
An = An(?) denotes the unique left distributive binary system on {0, 1,…,2n?1) that satisfies a ? 1 = a + 1 mod 2nfor all a ? An, and on(a) = k indicates the period 2kof a ? An (if b,c ? An, then a ? b = a ? c iff b ‵ c mod 2kand if 0 < b < c < 2kthen a < a ? b < a ? c). Amongs others, we prove that ot2(2t?2) ≤ t holds for every integer t ≥ 2, the equality taking place iff t is of the form 22? for an integer s ≥ 0. 相似文献
58.
Barbara Visintin 《Israel Journal of Mathematics》1999,112(1):1-27
A family of the spherical fractional integrals
on the unit sphere Σ
n
in ℝ
n+1 is investigated. This family includes the spherical Radon transform (α = 0) and the Blaschke-Levy representation (α>1). Explicit inversion formulas and a characterization ofT
αƒ are obtained for ƒ belonging to the spacesC
∞,C, Lp and for the case when ƒ is replaced by a finite Borel measure. All admissiblen ≥ 2,α ε ℂ, andp are considered. As a tool we use spherical wavelet transforms associated withT
α. Wavelet type representations are obtained forT
α ƒ, ƒ εL
p, in the case Reα ≤ 0, provided thatT
α is a linear bounded operator inL
p.
Partially supported by the Edmund Landau Center for Research in Mathematical Analysis, sponsored by the Minerva Foundation
(Germany). 相似文献
59.
60.
Barbara Nelli Ricardo Sa Earp Walcy Santos Eric Toubiana 《Annals of Global Analysis and Geometry》2008,33(4):307-321
We prove that a H-surface M in ${\mathbb{H}}^2 \times {\mathbb{R}} ,\vert H\vert \leq 1/2$ , inherits the symmetries of its boundary $\partial M,$ when $\partial M$ is either a horizontal curve with curvature greater than one or two parallel horizontal curves with curvature greater than one, whose distance is greater or equal to π. Furthermore we prove that the asymptotic boundary of a surface with mean curvature bounded away from zero consists of parts of straight lines, provided it is sufficiently regular. 相似文献