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The Index of Cusp Operators on Manifolds with Corners 总被引:3,自引:0,他引:3
We recall a Fredholm criterion for fully elliptic cusp(pseudo)differential operators on a compact manifold with corners ofarbitrary codimension, acting on suitable Sobolev spaces. Then we give aformula for the index in terms of regularized `trace' functionalssimilar to the residue trace of Wodzicki and Guillemin. 相似文献
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Lauter H Apaja V Kalinin I Kats E Koza M Krotscheck E Lauter VV Puchkov AV 《Physical review letters》2011,107(26):265301
We demonstrate by neutron scattering that a localized superfluid component exists at high pressures within solid helium in aerogel. Its existence is deduced from the observation of two sharp phonon-roton spectra which are clearly distinguishable from modes in bulk superfluid helium. These roton excitations exhibit different roton gap parameters than the roton observed in the bulk fluid at freezing pressure. One of the roton modes disappears after annealing the samples. Comparison with theoretical calculations suggests that the model that reproduces the observed data best is that of superfluid double layers within the solid and at the helium-substrate interface. 相似文献
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K.-U. Neumann F. Kusmartsev H.-J. Lauter O. Schärpf T.J. Smith K.R.A. Ziebeck 《The European Physical Journal B - Condensed Matter and Complex Systems》1998,1(1):5-9
A polarized neutron scattering investigation of the flux line lattice in the type-II superconductor niobium is reported. A
modulation of the nuclear lattice has been detected, and the magnitude of the first Fourier component of the lattice distortion
established relative to the magnitude of the magnetic scattering. This constitutes the first experimental observation of lattice
distortions due to the presence of magnetic flux lines within the bulk of a type-II superconductor. Using a simple microscopic
model the lattice distortion in niobium is estimated. A new mechanism is suggested for the coupling of the flux line lattice
to the crystallographic lattice. The experimental technique opens up the possibility of investigating the microscopic mechanism
of flux line - nuclear lattice interactions, in particular the pinning of flux lines within the bulk of a type-II superconductor.
Received: 8 August 1997 / Accepted: 16 October 1997 相似文献
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Measurements are reported on the isothermal, gravitational flow of liquid He II through narrow plane slits. The employed superleak consists of ring-shaped Hostaphan foils packed in layers. The distance between the foils is varied by pressure. The performance of the measurements and the observance of the isothermal conditions are described. The velocity of the superfluid component of He II is calculated in dependence on the width of the slits, the temperature and the hydrostatic pressure. Especially the critical velocity is considered. 相似文献
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I. V. Kalinin E. Kats M. Koza V. V. Lauter H. Lauter A. V. Puchkov 《JETP Letters》2008,87(11):645-648
Evidence of a superfluid liquid phase present in polycrystalline helium at a temperature of 0.2 K and a pressure of 51 bar has been obtained by means of inelastic neutron scattering. The superfluid component is absent at a temperature of 0.6 K and the same pressure. Thus, a “solid helium-superfluid helium” phase transition has been discovered. The sample of solid helium in a porous medium (silica aerogel) has been prepared with the use of a capillary blocking technique. The shape of the structure factor of the superfluid phase indicates the presence of clusters or the effects of a restricted geometry. The results may be used to explain the nonclassical rotational inertia phenomenon in solid helium (often referred to as supersolidity, Nature, 2004). 相似文献
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H. Lauter V. Lauter A. Vorobiev M. Mylaev L. Romashev V. Ustinov B. Toperverg 《Physica B: Condensed Matter》2009,404(17):2553-2556
Additional information about the magnetization distribution in magnetic films is obtained with a 3D-polarimetry set-up. A pilot experiment was performed with the neutron polarization aligned perpendicular to the surface of a Fe-film in a magnetic field parallel to its surface. The Larmor-precession in the magnetic field between two current sheets was used to adjust the neutron polarization perpendicular to the sample surface. This new polarization-magnetization configuration was probed with a Fe-film in specular and off-specular scattering. The off-specular scattering is created by the magnetic domain structure of the Fe-film in remanence. The results of specular and off-specular scattering are reproduced by calculations for the configuration of the incoming neutron polarization parallel to the sample surface and the magnetic field and for the configuration of the incoming neutron polarization perpendicular to the sample surface and the magnetic field. 相似文献
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V. V. Isaev-Ivanov D. V. Lebedev H. Lauter R. A. Pantina A. I. Kuklin A. Kh. Islamov M. V. Filatov 《Physics of the Solid State》2010,52(5):1063-1073
The nucleosome structure in native nuclei of normal (chicken erythrocyte and rat leukocyte nuclei) and anomalously proliferating
(the human cervical adenocarcinoma cell line HeLa and the Chinese hamster fibroblast cell line A238) cells has been investigated
using small-angle neutron scattering. The experimental results obtained allow one to make the inference that the parameters
of the nucleosome structure for the chicken erythrocyte and rat leukocyte nuclei (on average over the nucleus) are close to
the universally accepted values and that the distance distribution function is bimodal. The bimodality of the distance distribution
function reflects a narrow distribution of distances between nucleosomes (on average over the nucleus) at the fibril level
of the chromatin organization. The histone core of the nucleosome structure in the nuclei of the HeLa and A238 cells (on average
over the nucleus) is considerably less compact than that in the chicken erythrocyte and rat leukocyte nuclei, and the distance
distribution function does not exhibit indications of the bimodality. 相似文献
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I. V. Kalinin H. Lauter A. V. Puchkov 《Journal of Experimental and Theoretical Physics》2007,105(1):138-141
The results of the investigation of the temperature evolution of the scattering law S(Q, ω) of superfluid helium measured in the wave-vector range 0.3 < Q < 0.8 Å?1 and helium temperatures from 1.0 to 2.2 K are reported. The investigations have been performed on the high-flux reactor at the Institut Laue-Langevin (France) with the IN6 neutron inelastic-scattering spectrometer. The deviation of the experimental scattering law of liquid helium from the damping harmonic oscillator model, which was previously observed independently in the experiments with the IN6 spectrometer [1] and with the DIN-2PI spectrometer (at the IBR-2 reactor, Dubna, Russia) [2, 3] and were more recently called extrapeak, has been corroborated. The temperature dependence of the extrapeak parameters has been determined. This dependence makes it possible to propose hypotheses on the nature of the extrapeak. 相似文献