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91.
Martin V. Day 《Applied Mathematics and Optimization》1986,14(1):49-54
This paper is essentially an addendum to a previous paper [3] on the regularity properties of the Ventcel-Freidlin quasipotential function. We give here a proof of our conjecture regarding an exterior sphere condition for level sets.This work was supported in part by the National Science Foundation under grant DMS-8420755. 相似文献
92.
Early detection of (pre-)cancerous changes improves prognosis, therefore in the UK patients at high risk of developing gastrointestinal cancers are enrolled on endoscopic surveillance programmes or the Bowel Cancer Screening Programme. The current gold standard technique for the detection of pre-cancerous changes in the gastrointestinal tract is histopathological analysis of biopsy tissue collected at endoscopy. This relies upon subjective assessment of morphological changes within the excised tissue samples and poor targeting of pre-malignant lesions. Raman spectroscopy offers a number of potential advantages for in vivo assessment of tissue at endoscopy. The performance of a custom built Raman probe as a biopsy targeting tool has been evaluated using excised biopsy material. Multivariate classification models have been used to demonstrate the likely ability of a miniature, confocal, fibre optic Raman probe to be used as an optical biopsy tool at endoscopy to provide spectral information in clinically practicable timescales. This technique could facilitate improved targeting of excisional biopsy with associated clinical benefits. 相似文献
93.
Maher TR Spaeth AD Neal BM Berrie CL Thompson WH Day VW Barybin MV 《Journal of the American Chemical Society》2010,132(45):15924-15926
The key step in accessing the title species (5), the first nonbenzenoid diisocyanobiaryl, involved an unexpected homocoupling of a 6-bromoazulene derivative. The reversible 2e(-) reduction of 5 was addressed electrochemically and computationally. The shifts in energies of the S(0)→S(1) and S(0)→S(2) transitions for a series of related 6,6'-biazulenyl derivatives correlate with the e(-)-donating/-withdrawing strength of their 2,2'-substituents but follow opposite trends. Species 5 adsorbs end-on (η(1)) to the Au(111) surface via one of its -NC groups to form a 2-nm-thick film. In addition, bimetallic coordination of 5's -NC termini can be readily achieved. 相似文献
94.
Li R Zeitler JA Tomerini D Parrott EP Gladden LF Day GM 《Physical chemistry chemical physics : PCCP》2010,12(20):5329-5340
The phonon modes of crystalline benzoic acid have been investigated using terahertz time-domain spectroscopy, rigid molecule atom-atom model potential and plane-wave density functional theory lattice dynamics calculations. The simulation results show good agreement with the measured terahertz spectra and an assignment of the terahertz absorption features of benzoic acid is made with the help of both computational methods. Focussing on the strongest interactions in the crystal, we describe each vibration in terms of distortions of the benzoic acid hydrogen bonded dimers that are present in the crystal structure. The terahertz spectrum is also shown to be highly sensitive to the location of the carboxylic acid hydrogen atoms in the cyclic hydrogen-bonded dimers and we have systematically explored the influence of the observed disorder in the hydrogen atom positions on the lattice dynamics. 相似文献
95.
An ene-yne cross methasis of silyl-substituted alkynes and alkenes has been developed as a route to 4-aryl- and 4-alkyl-2-silyl-substituted 1,3-dienes. The dienes prepared were used to affect highly diastereoselective Diels-Alder reactions and then the silicon-substituted Diels-Alder cycloadducts were used in Hiyama cross-coupling reactions. The cross-coupling reactions enable these silicon dienes to be used as synthons for a variety of other dienes one might prepare and need access to. Two of the silicon-substituted Diels-Alder cycloadducts and one of the Hiyama cross-coupling products were also characterized by X-ray crystallography. 相似文献
96.
On the inversion of diffusion NMR data: Tikhonov regularization and optimal choice of the regularization parameter 总被引:1,自引:0,他引:1
Day IJ 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2011,211(2):178-185
The analysis of diffusion NMR data in terms of distributions of diffusion coefficients is hampered by the ill-posed nature of the required inverse Laplace transformation. Na?ve approaches such as multiexponential fitting or standard least-squares algorithms are numerically unstable and often fail. This paper updates the CONTIN approach of the application of Tikhonov regularization to stabilise this numerical inversion problem and demonstrates two methods for automatically choosing the optimal value of the regularization parameter. These approaches are computationally efficient and easy to implement using standard matrix algebra techniques. Example analyses are presenting using both synthetic data and experimental results of diffusion NMR studies on the azo-dye sunset yellow and some polymer molecular weight reference standards. 相似文献
97.
98.
M. E. Keillor L. E. Erikson C. E. Aalseth A. R. Day E. S. Fuller B. D. Glasgow E. W. Hoppe T. W. Hossbach L. K. Mizouni A. W. Myers C. T. Overman A. Seifert T. J. Stavenger 《Journal of Radioanalytical and Nuclear Chemistry》2013,296(2):683-687
The Pacific Northwest National Laboratory (PNNL) is currently developing a custom software suite capable of automating many of the tasks required to accurately analyze coincident signals within gamma spectrometer arrays. During the course of this work, significant crosstalk was identified in the energy determination for spectra collected with a new low-background intrinsic germanium (HPGe) array at PNNL. The HPGe array is designed for high detection efficiency, ultra-low-background performance, and sensitive γ–γ coincidence detection. The first half of the array, a single cryostat containing seven HPGe crystals, was recently installed into a new shallow underground laboratory facility. This update will present a brief review of the germanium array, describe the observed crosstalk, and present a straight-forward empirical correction that significantly reduces the impact of this crosstalk on the spectroscopic performance of the system. 相似文献
99.
In this letter, we report on, for the first time, the successful femtosecond micro-fabrication of continuous waveguide-like channels in the photorefractive polymer consisting of the nonlinear chromophore 2,5-dimethyl-4-(p-nitrophenylazo)anisole (DMNPAA), the photosensitive compound 2,4,7-trinitro-9-flourenone (TNF), and the plasticiser N-ethylcarbazole (ECZ) all doped in the polymer matrix poly (methyl methacry-late) (PMMA). These channels are caused by the change in refractive index as a result of the localised heating of the polymer and therefore have an important potential for micro-photonic devices in future. 相似文献
100.
We consider piecewise smooth viscosity solutions to a Hamilton-Jacobi equation, for which the Hamiltonian is the maximum of
a finite number of smooth concave functions. We describe the possible types of “basic” singularities, namely jump discontinuities
in either the derivative of the solution or the Hamiltonian, which occur across a smooth hypersurface. Each such type of singularity
is described in terms of the properties of the Hamiltonian and the classical characteristics in the regions on either side
of the singularity. Where appropriate, singular characteristic equations of the types developed by Melikyan are formulated
which can be used in constructions. 相似文献