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21.
A different approach, aiming to achieve the constant blur status of point-spread function (PSF) at a certain defocused plane,
is described. The correlation between the two PSF is used to control the PSF blur similarity, and simultaneously the Strehl
ratio is also used to control the PSF blur minimization. By designing the PSF so that it is significantly insensitive to defocus
or related defocus quantity, for example, due to temperature change, all the constantly blurred images can be accurately de-blurred
by a simple inverse restoration filter for an adequate range of defocus. We refer to that as “software lens compensation”
and apply a design method to solve the athermalization of middle wavelength infrared (MWIR) imaging systems. The resultant
PSF is almost invariant in the temperature range from −10 to 50°C at the same focal plane. Consequently, the constant blur
spot can be removed by a simple digital signal processing. Thus, clear and sharp de-blurred images at different temperatures
are obtained. 相似文献
22.
Zou Y Fahmi NE Vialas C Miller GM Hecht SM 《Journal of the American Chemical Society》2002,124(32):9476-9488
Metabolic inactivation of the antitumor antibiotic bleomycin is believed to be mediated exclusively via the action of bleomycin hydrolase, a cysteine proteinase that is widely distributed in nature. While the spectrum of antitumor activity exhibited by the bleomycins is believed to reflect the anatomical distribution of bleomycin hydrolase within the host, little has been done to characterize the product of the putative inactivation at a chemical or biochemical level. The present report describes the synthesis of deamidobleomycin demethyl A(2) (3) and deamido bleomycin A(2) (4), as well as the respective aglycones. These compounds were all accessible via the key intermediate N(alpha)-Boc-N(beta)-[1-amino-3(S)-(4-amino-6-carboxy-5-methylpyrimidin-2-yl)propion-3-yl]-(S)-beta-aminoalanine tert-butyl ester (16). Synthetic deamido bleomycin A(2) was shown to be identical to the product formed by treatment of bleomycin A(2) with human bleomycin hydrolase, as judged by reversed-phase HPLC analysis and (1)H NMR spectroscopy. Deamido bleomycin A(2) was found to retain significant DNA cleavage activity in DNA plasmid relaxation assays and had the same sequence selectivity of DNA cleavage as bleomycin A(2). The most significant alteration of function noted in this study was a reduction in the ability of deamido bleomycin A(2) to mediate double-strand DNA cleavage, relative to that produced by BLM A(2). 相似文献
23.
We conduct numerical simulations of random packings of frictionless particles at T = 0. The packing fraction where the pressure becomes nonzero is the same as the jamming threshold, where the static shear modulus becomes nonzero. The distribution of threshold packing fractions narrows, and its peak approaches random close packing as the system size increases. For packing fractions within the peak, there is no self-averaging, leading to exponential decay of the interparticle force distribution. 相似文献
24.
In a review paper [H. M. Jaeger, S. R. Nagel, and R. P. Behringer, "Granular solids, liquids and gases," Rev. Mod. Phys. 68, 1259-1273 (1996)] a few years ago, we wrote about granular material as a distinctive form of matter that exhibits behavior rather different from that of ordinary solids, liquids, or gases. We traced this distinction to three characteristic properties. First, the individual particles making up a granular material are typically large so that thermal energy is irrelevant compared to gravitational energy. Consequently, concepts from equilibrium statistical mechanics are often not applicable. Second, the interactions between particles are frictional and can be mobilized to different degrees depending on the preparation history, giving rise to memory effects, i.e., a static pile will remember how it was formed. Third, when particles collide they do so inelastically so that a "gas" of particles will slow down and come to rest in clumps. In the intervening years, the research on granular matter has progressed rapidly and this may be a good time to ask what we have learned since that article was written. In this spirit, the present special issue of the journal Chaos assembles a spectrum of papers discussing recent developments in the field. (c) 1999 American Institute of Physics. 相似文献
25.
It is shown in this paper that if A is a closed normal subgroup of kω-topological groups G and H, then the free product of G and H with A amalgamated, G1AH, exists, is Hausdorff and indeed a kω-group. 相似文献
26.
Sidney C. Scull 《Reports on Mathematical Physics》1976,10(1):1-7
The spectrum of self-adjoint operators arising from unitary representations of semi-simple Lie groups is investigated. A series of irreducible unitary representations in which certain generators of non-compact one-parameter subgroups are realized by positive operators is described. These representations occur only for groups of automorphisms of bounded symmetric domains. 相似文献
27.
The rate of the reaction CH2I2 + HI ? CH3I + I2 has been followed spectrophotometrically from 201.0 to 311.2°. The rate constant for the reaction fits the equation, log (k1/M?1 sec?1) = 11.45 ± 0.18 - (15.11 ± 0.44)/θ. This value, combined with the assumption that E2 = 0 ± 1 kcal/mole, leads to ΔH (CH2I, g) = 55.0 ± 1.6 kcal/mole and DH (H? CH2I) = 103.8 ± 1.6 kcal/mole. The kinetics of the disproportionation, 2 CH3I ? CH4 + CH2I2 were studied at 331° and are compatible with the above values. 相似文献
28.
29.
The reaction \documentclass{article}\pagestyle{empty}\begin{document}${\rm Br} + {\rm CH}_3 {\rm CHO}\buildrel1\over\rightarrow{\rm HBr} + {\rm CH}_3 {\rm CO}$\end{document} has been studied by VLPR at 300 K. We find k1 = 2.1 × 1012 cm3/mol s in excellent agreement with independent measurements from photolysis studies. Combining this value with known thermodynamic data gives k-1 = 1 × 1010 cm3/mol s. Observations of mass 42 expected from ketene suggest a rapid secondary reaction: in which step 2 is shown to be rate limiting under VLPR conditions and k2 is estimated at 1012.6 cm3/mol s from recent theoretical models for radical recombination. It is also shown that 0 ? E1 ? 1.4 kcal/mol using theoretical models for calculation of A1 and is probably closer to the lower limit. Reaction ?1 is negligible under conditions used. 相似文献
30.
The high-pressure absolute rate constants for the decomposition of nitrosobenzene and pentafluoronitrosobenzene were determined using the very-low-pressure pyrolysis (VLPP) technique. Bond dissociation energies of DH0(C6H5? NO) = 51.5 ± 1 kcal/mole and DH0 (C6F5? NO) = 50.5 ± 1 kcal/mole could be deduced if the radical combination rate constant is set at log kr(M?1·sec?1) = 10.0 ± 0.5 for both systems and the activation energy for combination is taken as 0 kcal/mole at 298°K. δHf0(C6H5NO), δHf0(C6F5NO), and δHf0(C6F5) could be estimated from our kinetic data and group additivity. The values are 48.1 ± 1, –160 ± 2, and – 130.9 ± 2 kcal/mole, respectively. C–X bond dissociation energies of several perfluorinated phenyl compounds, DH0(C6F5–X), were obtained from the reported values of δHf0(C6F5X) and our estimated δHf0(C6F5) [X = H, CH3, NO, Cl, F, CF3, I, and OH]. 相似文献