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191.
192.
Photo-induced enhancement of charge density wave current in the quasi-one-dimensional conductor TaS3
In the near vicinity of Peierls transition temperature TP, we have measured the V-I characteristics of the quasi-one-dimensional conductor TaS3 under dark and photo-irradiation conditions. It is found that a significant enhancement of CDW current occurs only around the threshold voltage Vt under photo-irradiation. This effect can be interpreted as a result of screening of pinning potential for CDW condensate by photo-excited quasi-particles (QP's). Further the distribution of pinning potential intensity is reflected in the behavior of V-I characteristics near Vt. Our finding suggests that the strength of pinning potential can be controlled by the photo-excited QP's in quasi-1D conductors. 相似文献
193.
Mikio Namiki 《Foundations of Physics》1988,18(1):29-55
The many-Hilbert-spaces theory of quantum measurements, which was originally proposed by S. Machida and the present author, is reviewed and developed. Dividing a typical quantum measurement in two successive steps, the first being responsible for spectral decomposition and the second for detection, we point out that the wave packet reduction by measurement takes place at the latter step, through interaction of an object system with one of the local systems of detectors. First we discuss the physics of the detection process, using numerical simulations for a simple detector model, and then formulate a general theory of quantum measurements to give the wave packet reduction in an explicit form as a sort of phase transition. The derivation is based on the macroscopic nature of the local system, to be represented in a continuous direct sum of many Hilbert spaces, and on the finite-size effect of the local system, to give phase shifts proportional to size parameters. We give a definite criterion for examining any instrument as to whether it works well as a detector or not. Finally, we compare the present theory with famous measurement theories and propose a possible experimental test to discriminate it from others. A few solvable detector models are also discussed. 相似文献
194.
Dihydropyrrolo[3,2-b]pyrrole was synthesized starting from 1,4-bis(trimethylsilyl)benzene. 相似文献
195.
Ilko K. Ilev Hiroshi Kumagai Koichi Toyoda Deepak Uttamchandani Brian Culshaw 《Optical Review》1997,4(1):A58-A60
An alternative and simple fiber-optic backreflectance sensor method for accurate measurement of either effective focal lengths
of optical elements and short distances using a single-mode optical fiber and cw laser is presented. The method is based on
the intensity sensing of focused backreflectance laser emission and the spatial location of three specific points: the focal
point of the focusing optical element and two object points. The single-mode fiber is a key optical element and serves simultaneously
as a point laser source for testing, an object for projecting and a highly sensitive point receiver of the focused backreflectance
emission. The experimental and analytical results demonstrate the potential of the method for locating the spatial points
and determining the effective focal length with accuracies exceeding 1 μm and 0.5%, respectively, as well as for short distance
measurement with submicron accuracy. 相似文献
196.
197.
Shinichi Suto Hirotada Ise Mikio Karasawa 《Journal of Polymer Science.Polymer Physics》1986,24(7):1515-1524
An Abbé refractometer with a rotatable polarizer mounted on the eyepiece is used for determining the two principal refractive indices of birefringent concentrated solutions of ethyl cellulose in m-cresol and in acetic acid. At a certain concentration, birefringence appears for both systems, and the concentration agrees with that for the onset of iridescence (here defined as the critical concentration Ca for formation of the liquid-crystalline phase). The birefringence of concentrated solutions depends strongly on concentration and temperature and can be generalized by a master curve. The refractive index increments for both systems are almost independent of temperature at high concentrations. 相似文献
198.
Chitsakon Pakjamsai Noritomo Kobayashi Mikio Koyano Shintaro Sasaki Yusuke Kawakami 《Journal of polymer science. Part A, Polymer chemistry》2004,42(18):4587-4597
The insoluble fraction obtained from the hydrolysis and condensation of (4-dimethylamino-, 2-methyl-, and nonsubstituted)phenyltrimethoxysilanes in the presence of benzyltrimethylammonium hydroxide in benzene was characterized. IR, 1H NMR, and 29Si NMR suggested that the insoluble fraction was composed of RSi(O )3, that is, a T3 structure. X-ray diffraction indicated the presence of a long-range ordered structure composed of a mixture of crystals. Raman spectroscopy strongly suggested a cage structure by the presence of a ring-opening vibration assignable to a cubic structure at 475–482 cm−1. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 4587–4597, 2004 相似文献
199.
200.
On the von Neumann-Jordan constant for Banach spaces 总被引:2,自引:0,他引:2
Let be the von Neumann-Jordan constant for a Banach space . It is known that for any Banach space ; and is a Hilbert space if and only if . We show that: (i) If is uniformly convex, is less than two; and conversely the condition implies that admits an equivalent uniformly convex norm. Hence, denoting by the infimum of all von Neumann-Jordan constants for equivalent norms of , is super-reflexive if and only if . (ii) If , (the same value as that of -space), is of Rademacher type and cotype for any with , where ; the converse holds if is a Banach lattice and is finitely representable in or .