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921.
I. R. Eghrari E. Costa Monteiro P. Costa Ribeiro J. P. von der Weid P. M. Oliveira A. Paes de Carvalho 《Il Nuovo Cimento D》1983,2(2):346-355
Summary To study the effect of the volume conductor geometry on the MCG, experiments using isolated rabbit hearts were done. An increase
of the magnetic signal when increasing the volume conductor’s size was observed. The results are discussed by using a fixed-origin
current dipole and a voltage source model for the heart.
Work supported by Brazilian Agencies CNPq, CAPES and FINEP. 相似文献
922.
Freedman B Carmon T Carvalho MI Segev M Christodoulides DN 《Physical review letters》2003,91(13):133902
We report the first experimental observation of optical spatial shock-wave pairs. The shock waves consist of two coupled kink and antikink beams that remain locked to each other throughout propagation in a nonlinear diffusion-driven photorefractive crystal. These coupled shock-wave pairs move undistorted at angles that fall outside their original angular sector of propagation. 相似文献
923.
de Carvalho EM Velloso MH Tinoco LW Figueroa-Villar JD 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2003,164(2):1-204
A study of the nature of the anthelmintic p-cresol:piperazine complex in chloroform solution has been conducted using different NMR techniques: self-diffusion coefficients using DOSY; NOE, NULL, and double-selective T1 measurements to determine inter-molecular distances; and selective and non-selective T1 measurements to determine correlation times. The experimental results in solution and CP-MAS were compared to literature X-ray diffraction data using molecular modeling. It was shown that the p-cresol:piperazine complex exists in solution in a very similar manner as it does in the solid state, with one p-cresol molecule hydrogen bonded through the hydroxyl hydrogen to each nitrogen atom of piperazine. The close correspondence between the X-ray diffraction data and the inter-proton distances obtained by NULL and double selective excitation techniques indicate that those methodologies can be used to determine inter-molecular distances in solution. 相似文献
924.
Abbott B Abolins M Abramov V Acharya BS Adams DL Adams M Alves GA Amos N Anderson EW Baarmand MM Babintsev VV Babukhadia L Baden A Baldin B Balm PW Banerjee S Bantly J Barberis E Baringer P Bartlett JF Bassler U Bean A Begel M Belyaev A Beri SB Bernardi G Bertram I Besson A Bezzubov VA Bhat PC Bhatnagar V Bhattacharjee M Blazey G Blessing S Boehnlein A Bojko NI Borcherding F Brandt A Breedon R Briskin G Brock R Brooijmans G Bross A Buchholz D Buehler M Buescher V Burtovoi VS Butler JM Canelli F 《Physical review letters》2001,86(12):2523-2528
The D0 Collaboration has measured the inclusive jet cross section in barpp collisions at square root of s = 630 GeV. The results for pseudorapidities (eta)<0.5 are combined with our previous results at square root of s = 1800 GeV to form a ratio of cross sections with smaller uncertainties than either individual measurement. Next-to-leading-order QCD predictions show excellent agreement with the measurement at 630 GeV; agreement is also satisfactory for the ratio. Specifically, despite a 10% to 15% difference in the absolute magnitude, the dependence of the ratio on jet transverse momentum is very similar for data and theory. 相似文献
925.
We review the construction of topological Yang–Mills theory (TYMT) from the point of view of an operator satisfying d = [, b] with b the BRST operator. We focus our attention on a situation in which [, d] 0 and show how this leads us to consider a more general derivative ~d = b + d +
k 2
k
1–k
. 相似文献
926.
Raman spectra of fluorine doped silica samples have been investigated. A model for dopant incorporation into the silica network is suggested, involving the formation of a SiO3F tetrahedron. The relationship between refractive index and intensity of the γ (SiF) vibration band is presented. 相似文献
927.
F. Carvalho Rodrigues 《The Journal of the Operational Research Society》1989,40(8):789-793
This paper describes a method for assessing the combat degradation of an army, based on the Shannon entropy measure. It is shown that this measure is useful for analysing combat degradation due to casualties, since it is in broad agreement with the values established from past battle experience. It is also shown that the measure can be used to evaluate the degree of confidence in the outcome of training manoeuvres when weapons simulators are employed. 相似文献
928.
Chris Carvalho William R. Cullen Michael D. Fryzuk Helen Jacobs Brian R. James James P. Kutney Krystyna Piotrowska Vinod K. Singh 《Helvetica chimica acta》1989,72(2):205-212
Employing thujone-derived intermediates, a series of achiral ( 9a–d ; Scheme 1) and chiral ( 11b and 11d; Scheme 2) terpene analogues related to the biologically active ‘terpenoid’ hybrids have been prepared. The stereochemistry of the key epoxidation reaction was established by correlation of the product 11b with the previously reported alcohol (R)- 20 of known absolute configuration (Scheme 3). 相似文献
929.
930.
A grid-embedding technique for the solution of two-dimensional incompressible flows governed by the Navier-Stokes equations is presented. A finite volume method with collocated primitive variables is employed to ensure conservation at the interfaces of embedding grids as well as global conservation. The discretized equations are solved simultaneously for the whole domain, providing a strong coupling between regions of different refinement. The formulation presented herein is applicable to uniform or non-uniform Cartesian meshes. The method was applied to the solution of two scalar transport equations, to cavity flows driven by body and shear forces and to a sudden plane contraction flow. The numerical predictions are compared with the exact solutions when available and with experimental data. The results show that neither the convergence rate nor the stability of the method is affected by the presence of embedded grids. Embedded grids provide a better distribution of grid nodes over the computational domain and consequently the solution accuracy was improved. The grid-embedding technique proved also that significant savings in computing time could be achieved. 相似文献