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61.
We study a soliton in an optical lattice holding bosonic atoms quantum mechanically using both an exact numerical solution and quantum Monte Carlo simulations. The computation of the state is combined with an explicit account of the measurements of the numbers of the atoms at the lattice sites. In particular, importance sampling in the quantum Monte Carlo method arguably produces faithful simulations of individual experiments. Even though the quantum state is invariant under lattice translations, an experiment may show a noisy version of the localized classical soliton. 相似文献
62.
Kurkijärvi JE Nissi MJ Rieppo J Töyräs J Kiviranta I Nieminen MT Jurvelin JS 《Magnetic resonance imaging》2008,26(5):602-607
The depth-wise variation of T(2) relaxation time is known to reflect the collagen network architecture in cartilage, while the delayed Gadolinium Enhanced MRI of Cartilage (dGEMRIC) technique is sensitive to tissue proteoglycan (PG) concentration. As the cartilage PG content varies along the tissue depth, the depth-dependent accumulation of the contrast agent may affect the inherent T(2) of cartilage in a nonconstant manner. Therefore, T(2) and dGEMRIC are typically measured in separate MRI sessions. In the present in vitro MRI study at 9.4 T, depth-wise T(2) profiles and collagenous zone thicknesses as determined from T(2) maps in the absence and presence of Gd-DTPA(2-) (T(2) and T(2Gd), respectively) were compared in samples of intact human articular cartilage (n=65). These T(2) measures were further correlated with birefringence (BF) of polarized light microscopy (PLM) to quantify the ability of MRI to predict the properties of the collagen fibril network. The reproducibility of the T(2) measurement in the current setup was also studied. Typical tri-laminar collagen network architecture was observed both with and without Gd-DTPA(2-). The inverse of BF (1/BF) correlated significantly with both T(2) and T(2Gd) (r=0.91, slope=0.56 and r=0.90, slope=0.63), respectively. The statistically significant linear correlations between zone thicknesses as determined from T(2) and T(2Gd) were r=0.55 (slope=0.49), r=0.74 (slope=0.71) and r=0.95 (slope=0.94) for superficial, middle and deep tissue zones, respectively. Reproducibility of the T(2) measurement was worst for superficial cartilage. Consistent with PLM, T(2) and T(2Gd) measurements reveal highly similar depth-dependent information on collagen network in intact human cartilage. Thus, dGEMRIC and T(2) measurements in one MRI session are feasible for intact articular cartilage in vitro. 相似文献
63.
In this paper we initiate the study of quasiregular maps in a sub-Riemannian geometry of general Carnot groups. We suggest
an analytic definition for quasiregularity and then show that nonconstant quasiregular maps are open and discrete maps on
Carnot groups which are two-step nilpotent and of Heisenberg type; we further establish, under the same assumption, that the
branch set of a nonconstant quasiregular map has Haar measure zero and, consequently, that quasiregular maps are almost everywhere
differentiable in the sense of Pansu. Our method is that of nonlinear potential theory. We have aimed at an exposition accessible
to readers of varied background.
Dedicated to Seppo Rickman on his sixtieth birthday
J.H. was partially supported by NSF, the Academy of Finland, and the A. P. Sloan Foundation. I.H. was partially supported
by the EU HCM contract no. CHRX-CT92-0071. 相似文献
64.
Ville Hyvrinen Mika Sorjonen Kai-Erik Peiponen Raimo Silvennoinen Tapani Niskanen Juha Kalliokoski 《Optics and Lasers in Engineering》2000,33(4):311
A technique for all-optical laser cleaning and surface quality monitoring of concave metal surfaces is suggested. Contaminated pharmaceutical punches from a tablet compression machine were cleaned using high-energy laser pulses. Image information obtained from a diffractive-optical-element-based sensor was used in inspection of the surface quality change of the concave punches due to laser cleaning. Alternative method for mechanical cleaning of punches is introduced, which is based on simultaneous laser cleaning and surface quality inspection of the punches. 相似文献
65.
rka Matu‐Ne
asov Adlia Sequeira Juha H. Videman 《Mathematical Methods in the Applied Sciences》1999,22(5):449-460
This paper deals with the existence and uniqueness of stationary solutions for the equations modelling the steady flow of compressible viscoelastic fluids of Oldroyd type in an exterior domain. The existence proof is based on an appropriate decomposition of the original nonlinear set of equations into auxiliar problems (Neumann problem for the Laplacian, Oseen problem, two transport equations) and on a fixed point argument in a suitable functional setting. Copyright © 1999 John Wiley & Sons, Ltd. 相似文献
66.
Some models for axially moving orthotropic thin plates are investigated analytically via methods of complex analysis to derive estimates for critical plate velocities. The linearized Kirchhoff plate theory is used, and the energy forms of steady-state models are considered with homogeneous and inhomogeneous tension profiles in the cross direction of the plate. With the help of the energy forms, some limits for the divergence velocity of the plate are found analytically. In numerical examples, the derived lower limits for the divergence velocity are analyzed for plates with small flexural rigidity. 相似文献
67.
68.
The kinetics of signal formation in collinear photofragmentation and atomic absorption spectroscopy (CPFAAS) are discussed, and theoretical equations describing the relation between the concentration of the target molecule and the detected atomic absorption in case of pure and impure samples are derived. The validity of the equation for pure samples is studied experimentally by comparing measured target molecule concentrations to concentrations determined using two other independent techniques. Our study shows that CPFAAS is capable of measuring target molecule concentrations from parts per billion (ppb) to hundreds of parts per million (ppm) in microsecond timescale. Moreover, the possibility to extend the dynamic range to cover eight orders of magnitude with a proper selection of fragmentation light source is discussed. The maximum deviation between the CPFAAS technique and a reference measurement technique is found to be less than 5 %. In this study, potassium chloride vapor and atomic potassium are used as a target molecule and a probed atom, respectively. 相似文献
69.
Nousiainen M Derrick PJ Kaartinen MT Mäenpää PH Rouvinen J Vainiotalo P 《Chemistry & biology》2002,9(2):195-202
Electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry was used to investigate Ca(2+), Mg(2+), and La(3+) binding to bovine bone osteocalcin (OCN). OCN was shown to bind 3 mol Ca(2+) per mol protein. There was also evidence for the presence of four additional metal binding sites. Ca(2+) increased the formation of the OCN dimer. Mg(2+) bound to OCN to the same extent as Ca(2+) but did not induce the dimerization of OCN. La(3+) bound to a lesser extent than either Ca(2+) or Mg(2+) to OCN and, like Mg(2+), did not influence dimerization. Each Gla residue of OCN participates in Ca(2+) binding, whereas Mg(2+) binding may occur preferentially at sites other than Gla residues. This implies that the different natures of Ca(2+)- and Mg(2+)-containing OCN complexes influence the tendency of OCN to form a dimer. 相似文献
70.