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31.
32.
M. R. Tinsley A. J. Steele K. Showalter 《The European physical journal. Special topics》2008,165(1):161-167
Stabilized waves in weakly excitable media propagate with constant velocity and can be directionally controlled with applied
excitability gradients. Multiple waves with directional control governed by pairwise interaction potentials form cohesive
groups. Processional modes arise in collections of waves with random initial conditions, in which spontaneous alignment plays
an essential role. Rotational modes occur with special initial conditions, and highly complex orbits are exhibited in larger
groups. The ordered behavior is associated with waves following paths of minimum potential. 相似文献
33.
A. F. Taylor P. Kapetanopoulos B. J. Whitaker R. Toth L. Bull M. R. Tinsley 《The European physical journal. Special topics》2008,165(1):137-149
We experimentally investigate the formation of clusters in a population of globally coupled photochemical oscillators. The
system consists of catalytic micro-particles in Belousov-Zhabotinsky solution and the coupling exploits the excitatory properties
of light; an increase in the light intensity leads to excitation (“firing") of an oscillator. As the coupling strength is
increased, a transition occurs from incoherence to clustering, whereby the oscillators split into synchronised groups, to
complete synchronisation. Multistability is observed between a one-phase cluster (fully synchronised group) and two-phase
clusters (two groups with the same frequency but different phases). The results are reproduced in simulations and we demonstrate
that the heterogeneity of the population as well as the relaxational nature of the oscillators is important in the observation
of clusters. We also examine the exploitation of the phase model for the prediction of clusters in experiments. 相似文献
34.
R.P. Liljestrand J.M. Cameron D.A. Hutcheon R. MacDonald W.J. McDonald C.A. Miller W.C. Olsen J.J. Kraushaar J.R. Shepard J.G. Rogers J.T. Tinsley C.E. Stronach 《Physics letters. [Part B]》1981,99(4):311-316
Cross sections and analyzing powers for the 13C(,d) reaction have been measured at 200 and 400 MeV to the 0+, ground state and 2+, 4.44 MeV state of 12C. While the cross sections are rather structureless, DWBA calculations in exact finite range account well for both the magnitude and shape of the angular distributions. On the other hand, the measured analyzing powers are in serious disagreement with the DWBA calculations. 相似文献
35.
A new approach to variable selection in least squares problems 总被引:9,自引:0,他引:9
The title Lasso has been suggested by Tibshirani (1996) as acolourful name for a technique of variable selection which requiresthe minimization of a sum of squares subject to an l1 bound on the solution. This forces zero components in the minimizingsolution for small values of . Thus this bound can functionas a selection parameter. This paper makes two contributionsto computational problems associated with implementing the Lasso:(1) a compact descent method for solving the constrained problemfor a particular value of is formulated, and (2) a homotopymethod, in which the constraint bound becomes the homotopyparameter, is developed to completely describe the possibleselection regimes. Both algorithms have a finite terminationproperty. It is suggested that modified Gram-Schmidt orthogonalizationapplied to an augmented design matrix provides an effectivebasis for implementing the algorithms. 相似文献
36.
P.A. Mosier-Boss L.P.G. ForsleyP. Carbonnelle M.S. MoreyJ.R. Tinsley J.P. HurleyF.E. Gordon 《Radiation measurements》2012,47(1):57-66
A solid state nuclear track detector, CR-39, was exposed to DT neutrons. After etching, the resultant tracks were analyzed using both an optical microscope and a scanning electron microscope (SEM). In this communication, both methods of analyzing DT neutron tracks are discussed. 相似文献
37.
RM. Murugappan M. Karthikeyan A. Aravinth MR. Alamelu 《Applied biochemistry and biotechnology》2012,168(8):2170-2183
In the present study, siderophore produced by the marine yeast Aureobasidium pullulans was characterized as hydroxamate by chemical and bioassays. The hydroxamate assignment was supported by the appearance of peaks at 1,647.21?C1,625.99?cm?1 and at 1,435.04?cm?1 in the infrared spectrum. The purified siderophore exhibited specific growth-promoting activity under iron-limited conditions for siderophore auxotrophic probiotic bacteria. Cross-utilization of siderophore indicates a symbiotic relationship between the yeast A. pullulans and the selected probiotic bacterial strains. Statistical optimization of medium components for improved siderophore production in A. pullulans was depicted by response surface methodology. The shift in UV?CVis spectroscopy indicates the photoreactive property and subsequent oxidative cleavage of purified siderophore on exposure to sunlight. 相似文献
38.
39.
MR Eskildsen AB Abrahamsen PL Gammel DJ Bishop NH Andersen K Mortensen PC Canfield 《Pramana》2002,58(5-6):903-905
We compare the results of small angle neutron scattering on the flux line lattice (FLL) obtained in the borocarbide superconductor
LuNi2B2C with the applied field along the c- and a-axes. For H‖c the temperature dependence of the FLL structural phase transition from square to hexagonal symmetry was investigated. Above
10 K the transition onset field. H
2(T), rises sharply, bending away from H
c2(T) in contradiction to theoretical predictions of the two merging. For H‖a a first order FLL reorientation transition is observed at H
tr=3–3.5 kOe. Below H
tr the FLL nearest neighbor direction is parallel to the b-axis, and above H
tr to the c-axis. This transition cannot be explained using nonlocal corrections to the London model. 相似文献
40.
Nonlinear Dynamics - The parabolic leaf spring is widely used in modern vehicle suspension systems because it has many desirable features, such as weak interleaf friction and light weight. In this... 相似文献