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821.
822.
It is widely accepted from noise models that the extracted performance parameters such as spatial and temporal NEDT do not depend on the number of samples, which are used to estimate the noise values. Experimental studies have determined that noise values depend on the number of sampled data because of other noise contribution or its frequency dependence. This, however, creates ambiguities since unique values NEDT cannot be established without fixing the number of frames to be utilized. However in the frequency domain, values of parameters can be easily established at certain frequency. In the frequency domain it is also easier to study the noise contribution originating from various noise sources such as from the ROIC. This presentation will present preliminary analysis of spatial and temporal noise in the frequency domain by utilizing the power of FFT analysis. 相似文献
823.
Mehdi Asghari‐Khiavi Adam Mechler Keith R. Bambery Don McNaughton Bayden R. Wood 《Journal of Raman spectroscopy : JRS》2009,40(11):1668-1674
The effects of fixation and dehydration procedures on heme environment inside human erythrocytes were examined using resonance Raman spectroscopy. The resonance Raman spectroscopic data along with far‐infrared spectra show that hemoglobin in air‐dried red blood cells and those fixed in the precipitating fixatives, methanol and acetone, changes to hemichrome, a low‐spin component in which the sixth coordination site of the iron is occupied by the imidazole group of the distal histidine. The cross‐linking fixatives, formaldehyde and glutaraldehyde, maintain hemoglobin in its native conformational state (oxyhemoglobin) as evidenced by the appearance of the oxygen ligand marker bands along with the skeletal sensitive modes. However, polymerization with cross‐linking fixatives increases the auto‐oxidation kinetics of hemoglobin and gradually oxidizes it to the met state. Moreover, the dehydration of a red blood cell under N2 results in a change of oxyhemoglobin to a six coordinate low‐spin FeII derivative of hemoglobin, hemochrome. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
824.
在相同的反应体系中当ph值从约9.5调变至11时分别合成出双中孔SiO2和六方中孔SiO2材料,并用XRD、N2吸附、TEM、TG/DTA和FTIR等测试手段对合成产物进行了表征。实验结果表明,双中孔SiO和六 方中孔SiO2是合成中必然出现的两种不同的中孔物相。与六方中孔SiO2相比,双中孔SiO2也具有典型中孔 材料的特征XRD谱图,虽然仅呈现一个易让人产生不完全晶化误解的相对较宽的单XRD衍射峰(d=5.2nm),但它却给出一种独特的N2吸附等温线和窄的双峰中孔孔径分布曲线。由于孔壁的无定形及表面活性剂分子与SiO2骨架间相似的相互作用,两类材料给出类似的FTIR谱图和TG/DTA曲线。然而,在双中孔SiO2的FTIR谱图中960cm处峰强度的微小变化可能意味着在锻烧脱除模板剂后双中孔SiO2较六方中孔SiO2具有更高的骨架聚合度。 相似文献
825.
Don Hadwin 《Mathematische Annalen》2000,316(2):201-213
We show that if S is a pure subnormal operator, then the minimal normal extension can be written as with . We also extend the Kaplansky density theorem by proving that if is a unital -algebra of operators, then every subnormal contraction in is a (SOT) limit of normal contractions in . We prove similar results for subnormal tuples.
Received: 26 July 1998 / in final form: 30 March 1999 相似文献
826.
Sendt K Johnston LA Hough WA Crossley MJ Hush NS Reimers JR 《Journal of the American Chemical Society》2002,124(31):9299-9309
The use of a quinone functionality in the linkage unit of laterally bridged oligoporphyrins as a switch for controlling electronic coupling between the termini is examined. The quinone-bridged bisporphyrin P(2)TA-O(2) was synthesized by condensation of 2 equiv of the dione 2,3-dioxo-5,10,15,20-tetrakis(3,5-di-tert-butylphenyl)chlorin with 2,3,5,6-tetraamino-1,4-benzoquinone. The electronic absorption spectra of P(2)TA-O(2) and its conjugated benzenoid analogue P(2)TA are measured and assigned, in conjunction with the spectra of the fragment monomers and porphyrin-bridge compounds. Band homologies and CASPT2 calculations are used to make the assignments. Chemically, the dimer in one case is bridged by a through-conjugated, pi-delocalized 1,4,5,8-tetraazaanthracene molecule. This is shown to display significant inter-porphyrin coupling, with an observed difference in the exciton couplings of the B(x) and B(y) bands being ca. 0.18 eV. However, the other dimer is bridged using a derivative in which the central ring is converted to a cross-conjugated, pi-localized quinonoid form; this molecule displays no observable inter-porphyrin coupling. This scenario provides a paradigm for the use of molecular electronic devices in sensing, control, and high-capacity relatively low-speed data storage applications. 相似文献
827.
Weingarten D 《Physical review letters》2002,89(24):240201
We establish a necessary and sufficient condition for averages over complex-valued weight functions on R(N) to be represented as statistical averages over real, non-negative probability weights on C(N). Using this result, we show that many path integrals for time-ordered expectation values of bosonic degrees of freedom in real-valued time can be expressed as statistical averages over ensembles of paths with complex-valued coordinates, and then speculate on possible consequences of this result for the relation between quantum and classical mechanics. 相似文献
828.
Klei SR Golden JT Tilley TD Bergman RG 《Journal of the American Chemical Society》2002,124(10):2092-2093
The air-stable complex Cp(PMe(3))IrCl(2) efficiently catalyzes the exchange of deuterium from D(2)O into both activated and unactivated C-H bonds of organic molecules without added acid or stabilizers. Selectivity is observed in many cases, with activation of primary C-H bonds occurring preferentially. A number of new stoichiometric transformations involving the iridiym catalyst precursor are also presented, including an oxidation-decarbonylation reaction with primary alcohols. 相似文献
829.
Don Weingarten 《Nuclear Physics B》1982,210(2):229-245
We construct a number of related euclidean lattice formulations of quantum gravity. The first version incorporates a path integral over discrete manifolds built out of four-cubes embedded in a higher dimensional flat hypercubic lattice. We show this expression is equal to a corresponding path integral in a local lattice field theory. The field theoretic path integral diverges and lacks a satisfactory vacuum state. This divergence can be interpreted as a consequence of a divergent phase space available for topological fluctuations in the four-manifolds of the original path integral. A modified version of the path integral over manifolds converges. We construct a Schrödinger equation and hamiltonian for the modified theory. The hamiltonian is self-adjoint, but as a result of the large phase space available for topological fluctuations, the hamiltonian's spectrum is probably not bounded from below. We show briefly how the flat enveloping space—time can be removed from most of the theories we present and how matter fields can be included. 相似文献
830.