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11.
Given a Tychonov space X we can construct another space Y with the same group of homeomorphisms such that X and Y are, in some sense, "almost arbitrarily different". 相似文献
12.
The effective mass in degenerate InP is measured by means of the de Haas-Shubnikov effect observe in the transverse magnetoresistance. 相似文献
13.
M.S. Skolnick L. Eaves R.A. Stradling J.C. Portal S. Askenazy 《Solid State Communications》1974,15(8):1403-1408
The effects of intrinsic illumination on the far infrared photoconductivity of high purity Si and Ge are studied. Such illumination permits the observation of both the majority and minority impurities. One of the donors in Ge is highly sensitive to heat treatment, a result suggesting that it arises from lattice defects rather than chemical impurities. 相似文献
14.
E. B. Olshanetsky Z. D. Kvon D. V. Sheglov A. V. Latyshev A. I. Toropov J. C. Portal 《JETP Letters》2005,81(12):625-628
The temperature dependence of the Aharonov-Bohm oscillations of small quasi-ballistic ring interferometers (effective radius R = 90–110 nm) is studied in a wide temperature range of (0.34–9) K. It is found that this dependence is determined not only by the size of the interferometer, but also by its microscopic state. It is shown that the effect may be associated with the influence of the fluctuation potential leading to different, but not completely stochastic, realizations of the scattering potential in conducting channels of the ring. 相似文献
15.
John?F?StinsEmail author G?Caroline?M?van Baal Tinca?JC?Polderman Frank?C?Verhulst Dorret?I?Boomsma 《BMC neuroscience》2004,5(1):49
Background
There is great interest in appropriate phenotypes that serve as indicator of genetically transmitted frontal (dys)function, such as ADHD. Here we investigate the ability to deal with response conflict, and we ask to what extent performance variation on response interference tasks is caused by genetic variation. We tested a large sample of 12-year old monozygotic and dizygotic twins on two well-known and closely related response interference tasks; the color Stroop task and the Eriksen flanker task. Using structural equation modelling we assessed the heritability of several performance indices derived from those tasks. 相似文献16.
Fixed Point Index in Hyperspaces: A Conley-Type Index for Discrete Semidynamical Systems 总被引:2,自引:0,他引:2
Let X be a locally compact metric absolute neighbourhood retractfor metric spaces, U X be an open subset and f: U X be a continuousmap. The aim of the paper is to study the fixed point indexof the map that f induces in the hyperspace of X. For any compactisolated invariant set, K U, this fixed point index produces,in a very natural way, a Conley-type (integer valued) indexfor K. This index is computed and it is shown that it only dependson what is called the attracting part of K. The index is usedto obtain a characterization of isolating neighbourhoods ofcompact invariant sets with non-empty attracting part. Thisindex also provides a characterization of compact isolated minimalsets that are attractors. 相似文献
17.
Portal 《Semigroup Forum》2008,67(1):125-144
Abstract. We study different notions of discrete maximal regularity for discrete-time abstract Cauchy problems in Banach spaces. First
we look at l
2
-discrete maximal regularity and show that Hilbert spaces are the only Banach spaces, among spaces with an unconditional
basis, in which the analyticity of the associated discrete-time semigroup is a sufficient condition to obtain this kind of
regularity. We then turn to different notions of regularity, in a l
1
and in a l
∞
sense. We link the existence of particular semigroups such that the associated Cauchy problem has one of these maximal regularities
to the geometry of the underlying Banach space (more precisely, to the existence of a complemented subspace isomorphic to
c
0
or l
1
). Finally, we give some elements to compare these regularities. 相似文献
18.
Resume Il s'agit de majorer l'écart entre deux mesures aléatoires (la loi empirique d'un n échantillon et la vraie loi, un processus ponctuel et son compensateur prévisible, une mesure de Poisson et son intensité ...), ceci en vue d'applications statistiques. L'outil principal est l'information de Kullback des mesures bornées, qu'on étudie dans la première partie. On donne enfin des applications dans les quatrième et cinquième parties. La cinquième partie étant plus spécialement consacrée aux applications statistiques. 相似文献
19.
20.
V. A. Tkachenko Z. D. Kvon O. A. Tkachenko D. G. Baksheev O. Estibals J. -C. Portal 《Physica E: Low-dimensional Systems and Nanostructures》2004,21(2-4):469
An AlGaAs/GaAs lateral quantum dot of triangular shape with a characteristic size L<100 nm containing less than ten electrons was studied. Single-electron oscillations of the conductance G of this dot were measured at G<e2/h. When going from Ge2/h to G≈0.5e2/h, a decrease was found not only in the amplitude but also in the period of the oscillations. A calculation of the 3D-electrostatics demonstrated that this effect is due to a change in the dot size produced by control voltages. 相似文献