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211.
Background
Neurons require an elaborate system of intracellular transport to distribute cargo throughout axonal and dendritic projections. Active anterograde and retrograde transport of mitochondria serves in local energy distribution, but at the same time also requires input of ATP. Here we studied whether brain-type creatine kinase (CK-B), a key enzyme for high-energy phosphoryl transfer between ATP and CrP in brain, has an intermediary role in the reciprocal coordination between mitochondrial motility and energy distribution. Therefore, we analysed the impact of brain-type creatine kinase (CK-B) deficiency on transport activity and velocity of mitochondria in primary murine neurons and made a comparison to the fate of amyloid precursor protein (APP) cargo in these cells, using live cell imaging. 相似文献212.
van Der Lee AM van Druten NJ van Exter MP Woerdman JP Poizat JP Grangier P 《Physical review letters》2000,85(22):4711-4714
We investigate the impact of the Petermann-excess-noise factor K>/=1 on the possibility of intensity noise squeezing of laser light below the standard quantum limit. Using an N-mode model, we show that squeezing is limited to a floor level of 2(K-1) times the shot noise limit. Thus, even a modest Petermann factor significantly impedes squeezing, which becomes impossible when K>/=1.5. This appears as a serious limitation for obtaining sub-shot-noise light from practical semiconductor lasers. We present experimental evidence for our theory. 相似文献
213.
A. A. Vikharev G. G. Denisov Vl. V. Kocharovsky S. V. Kuzikov V. V. Parshin N. Yu. Peskov A. N. Stepanov D. I. Sobolev M. Yu. Shmelev 《Radiophysics and Quantum Electronics》2007,50(10-11):786-793
We study, both numerically and experimentally, a microwave commutator (phase shifter), whose active element comprises a metal plane mirror with a semiconductor plate on it. Phase shifting of the reflected microwave beam is attained by creating a conducting layer in the semiconductor by a laser with quantum energy approximately equal to the forbidden band width. Using a disk of high-purity silicon and a titatnium-sapphire pulsed laser, we study experimentally a 180° phase shifter operated with a Gaussian wave beam at a frequency of 30 GHz. Efficient phase shifting of the wave beam over a time of several nanoseconds is shown at a low power level. 相似文献
214.
Partial spectra of thermal vibrations of Al, Cu, and Fe atoms in an icosahedral quasicrystal have been obtained by the isotopic-contrast method in inelastic neutron scattering. Joint analysis of these results and the published data on the atomic and electronic structures of the icosahedral i-AlCuFe quasicrystal has been performed. A physical model of the quasicrystal structure is proposed that is in agreement with the existing experimental data and qualitatively describes the peculiarities of interatomic interaction. 相似文献
215.
The atomic dynamics of an Al-Ni-Fe decagonal quasicrystal and an Al-Cu-Fe icosahedral quasicrystal are investigated experimentally using the isotopic contrast method in inelastic neutron scattering. The partial spectra of thermal vibrations of copper, nickel, iron, and aluminum atoms in the decagonal and icosahedral quasicrystals are reconstructed directly from the experimental data without recourse to model concepts. The limiting energies and positions of the main features in the partial spectra of atomic thermal vibrations in decagonal and icosahedral quasicrystals are determined. It is established that, in the quasicrystals under investigation, the copper and nickel atoms are bound more weakly than the iron atoms and that the partial vibrational spectrum of aluminum atoms in the quasicrystals is considerably harder than the spectrum of pure metallic aluminum. 相似文献
216.
Experimental results on the density of states and on the acoustic modes of glasses in the THz region are compared to the predictions of two categories of models. A recent one, solely based on an elastic instability, does not account for most observations. Good agreement without adjustable parameters is obtained with models including the existence of nonacoustic vibrational modes at THz frequency, providing in many cases a comprehensive picture for a range of glass anomalies. 相似文献
217.
P. P. Parshin M. G. Zemlyanov R. A. Brand D. Pavlyuchkov J. Ollivier 《Physics of the Solid State》2010,52(7):1492-1498
The atomic dynamics of the Al0.550Si0.070Cu0.255Fe0.125 alloy with the structure that approximates the structure of an icosahedral quasicrystal with a similar chemical composition
has been investigated using inelastic neutron scattering. The partial vibrational spectra of copper, iron, and aluminum atoms
and the total spectrum of thermal vibrations of the compound have been directly reconstructed from the experimental data for
the first time. A combined analysis of the results obtained and the data on the atomic dynamics of the i-AlCuFe icosahedral quasicrystal has been performed. 相似文献
218.
G. Kh. Panova M. G. Zemlyanov P. P. Parshin A. A. Shikov R. A. Brand 《Physics of the Solid State》2010,52(4):771-775
The specific heat of decagonal Al71.3Ni24.0Fe4.7 and icosahedral Al62Cu25.5Fe12.5 quasicrystals and the Al55.0Si7.0Cu25.5Fe12.5 cubic phase approximating the structure of the icosahedral alloy has been studied in the temperature range 4.2–40.0 K. All
the three compounds exhibit low coefficients of the electronic heat capacity and pronounced deviations of the low-temperature
lattice heat capacity from a cubic temperature law in the range 5–10 K. The results obtained by the thermodynamic method and
inelastic neutron scattering have been compared and analyzed. It has been established that, at energies ɛ < 14 meV, the spectral
density of thermal vibrations in the icosahedral quasicrystal is substantially higher than those in the cubic approximant
and in decagonal quasicrystal. 相似文献
219.
An original method based on determining the characteristics of open Fabry-Perot resonator modes with different polarizations
is proposed for measuring parameters of dielectric plates and films with a thickness smaller than λ/2 in the millimeter and
submillimeter wavelength ranges. This method is used for determining the refractive index and tanδ, as well as the thickness
of films made of isotropic materials. For anisotropic films of known thickness, the method makes it possible to measure the
permittivity tensor components. Popular film materials such as Teflon (polytetrafluoroethylene, PTFE), lavsan (Mylar, polyethyleneterephthalate,
PETP), and polyamide with a minimal thickness of ∼5 μm are investigated. Appreciable anisotropy of roll film materials and
the dependence of the dielectric properties on the thickness, which is associated with manufacturing technology, are revealed.
The dependence of the refractive index and tanδ on the air humidity is investigated 相似文献
220.