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21.
This personal perspective is an attempt to look at the role and impact of virtual reality (VR) as related to medicine and
medical practice over the past 10–15 years. A similar treatise was recently published (Robb, 2002) in much shorter form. This
more complete version is still not intended to be, nor can it be, fully comprehensive and inclusive of all developments or
viewpoints. It is primarily based on the author’s experience and opinion. Although such a review begs for many references
to published works, that too is eschewed in the interest of preserving, for better or worse, the single view of the author
in this article. Only seven references are included which contain copious other references to much of the material touched
upon in this essay. To the extent that one can learn from history, this synopsis will also fall short, not so much due to
lack of confirming references, but rather because the impact of VR in medicine has been an evolutionary culmination of digression
and progression that has resulted in some success and useful contributions but also some wasted time and resources. 相似文献
22.
23.
Izmaylov AF Mendive-Tapia D Bearpark MJ Robb MA Tully JC Frisch MJ 《The Journal of chemical physics》2011,135(23):234106
We consider photoinduced electronic transitions through conical intersections in large molecules. Starting from the linear vibronic model Hamiltonian and treating linear diabatic couplings within the second order cumulant expansion, we have developed a simple analytical expression for the time evolution of electronic populations at finite temperature. The derived expression can be seen as a nonequilibrium generalization of the Fermi golden rule due to a nonequilibrium character of the initial photoinduced nuclear distribution. All parameters in our model are obtained from electronic structure calculations followed by a diabatization procedure. The results of our model are found to agree well with those of quantum dynamics for a test set of systems: fulvene molecule, 2,6-bis(methylene) adamantyl cation, and its dimethyl derivative. 相似文献
24.
25.
Let ρ21,…,ρ2p be the squares of the population canonical correlation coefficients from a normal distribution. This paper is concerned with the estimation of the parameters δ1,…,δp, where , i = 1,…,p, in a decision theoretic way. The approach taken is to estimate a parameter matrix Δ whose eigenvalues are δ1,…,δp, given a random matrix F whose eigenvalues have the same distribution as , i = 1,…,p, where r1,…,rp are the sample canonical correlation coefficients. 相似文献
26.
Speech duration characteristics of phrase-level utterances produced by 26 severely and profoundly hearing-impaired adults were examined acoustically using relative timing measures. The measures were then compared to the same utterances produced by 13 normal-hearing adults. Although absolute speech durations of the hearing-impaired subjects were significantly longer than their normal-hearing counterparts, relative timing did not differ between groups. Findings are discussed in relation to the biological constraint hypothesis associated with speech timing, as well as the role of auditory feedback in models of speech production. 相似文献
27.
The complexes PdCl42?, PdCl3(H2O)?, and PdCl3(Ac)2?, in rapid equilibrium with each other under the adopted experimental conditions, react with ethylenediamine according to the experimental rate law A reaction scheme is proposed involving the reaction of enH+ with each of the above species, and the specific rate constants are computed. The activation parameters are given. 相似文献
28.
This paper develops algebraic and convergence properties of the left and right block reflectors used in the block diagonalization algorithm. Several numerical illustrations are reported.AMS subject classification (2000) 65F20, 15A23.Submitted December 2002. Accepted October 2003. Communicated by Per Christian Hansen. 相似文献
29.
Asymptotic expansions, valid for large error degrees of freedom, are given for the multivariate noncentral F distribution and for the distribution of latent roots in MANOVA and discriminant analysis. The asymptotic results are expressed in terms of elementary functions which are easy to compute and the results of some numerical work are included. The Bartlett test of the null hypothesis that some of the noncentrality parameters in discriminant analysis are zero is also briefly discussed. 相似文献
30.
A mechanism of the thermal and photochemical bleaching of merocyanine to spiropyran is proposed on the basis of CASSCF/CASPT2 calculations on the 6-(2-propenyliden)cyclohexadienone model system. Our results suggest that this photochemical transformation takes place in two steps. First, the initially pumped 1(pi-pi) S2 undergoes radiationless decay to 1(n-pi) S1 via an extended S2/S1 conical intersection seam that runs approximately parallel to the trans-to-cis isomerization coordinate, a few kilocalories per mole higher in energy. Thus, S2 --> S1 internal conversion is possible at all values of the S2 trans-to-cis reaction coordinate. Second, on the S1 potential energy surface, there is a barrierless ring closure reaction path from the S1 cis minimum that leads to a peaked S1/S0 conical intersection where the deactivation to the ground state takes place. The inertia of the moving nuclei then drives the system toward the ground-state minimum of the 2H-chromene product. Thus, the extended seam topology of the S2/S1 conical intersection and the coordinate of the branching space of the S1/S0 conical intersection are essential to explain the efficiency and high speed of this reaction. 相似文献