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1.
2.
Dedicated to the memory of John Oxtoby 相似文献
3.
We present a Bayesian theory of object identification. Here, identifying an object means selecting a particular observation from a group of observations (variants), this observation (the regular variant) being characterized by a distributional model. In this sense, object identification means assigning a given model to one of several observations. Often, it is the statistical model of the regular variant, only, that is known. We study an estimator which relies essentially on this model and not on the characteristics of the “irregular” variants. In particular, we investigate under what conditions this variant selector is optimal. It turns out that there is a close relationship with exchangeability and Markovian reversibility. We finally apply our theory to the case of irregular variants generated from the regular variant by a Gaussian linear model. 相似文献
4.
Gunter M. Schütz 《Zeitschrift für Physik B Condensed Matter》1997,104(3):583-590
We study diffusion-limited (on-site) pair annihilation A + A → 0 and (on-site) fusion A + A → A which we show to be equivalent for arbitrary space-dependent diffusion and reaction rates. For one-dimensional lattices with nearest neighbour hopping we find that in the limit of infinite reaction rate the time-dependent n-point density correlations for many-particle initial states are determined by the correlation functions of a dual diffusion-limited annihilation process with at most 2n particles initially. Furthermore, by reformulating general properties of annihilating random walks in one dimension in terms of fermionic anticommutation relations we derive an exact representation for these correlation functions in terms of conditional probabilities for a single particle performing a random walk with dual hopping rates. This allows for the exact and explicit calculation of a wide range of universal and non-universal types of behaviour for the decay of the density and density correlations. 相似文献
5.
Gunter Zwilling 《Monatshefte für Chemie / Chemical Monthly》1981,112(2):157-165
The anodic overvoltage on carbon and platinum electrodes in the electrochemical production of high purity gadolinium from molten 75 LiF-25 mol% GdF3 solutions is discussed. At the cell temperature of 840°C calciumimpregnated anodes led to the reduction of inert electrode films and to a current yield of nearly 100%.The deposited gadolinium contained 75, 22, 54 and less than 100 ppm of the interstitial elements H, N, O and C respectively; the concentrations of the highest other analysed impurities were: Si (89), Fe (15), Y (5), Zr (3), Nd (3), Tb (71), Ta (49), W (23) and Re (<3 ppm).Partly performed at the Ames Laboratory—U.S. Department of Energy. 相似文献
6.
P. J. Hauser A. F. Schreiner J. D. Gunter W. J. Mitchell M. K. Dearmond 《Theoretical chemistry accounts》1972,24(1):78-88
MCD, electronic absorption, external heavy atom, and crystal field data are presented for the low energy region (2
E
g, 2
T
1g, 4
T
2g) and high energy region (2
T
2g, 4
T
1g) of Cr(dtp)3, Cr(dtc)3, and Cr(exan)3. At low energy, MCD intensities of 2
E(2
E
g) and 2
E(2
T
g) are as large or larger than 4
T
2g, and the MCD technique is advantageous over electronic absorption in this respect. The MCD positions of 2
E
g and 2
T
1g are nearly the same for these molecules ( 13 kK and 13.6 kK) · 4
T
2g of this region appears trigonally split ( 500 cm–1) in the MCD of dtp but to a smaller extent than in the electronic crystal spectrum of Lebedda and Palmer ( 600 cm–1). MCD did not resolve such components for exan and dtc. The higher energy region includes 2
T
2g and 4
T
1g, and the combined MCD and electronic absorption data of the three compounds taken together lead us to conclude the ordering 2
A
1(2
T
2g)<2
E(2
T
2g)<4
E(4
T
1g). The potentially useful external heavy atom affect on the solution-observed electronic 2
E and 4
E bands of Cr(dtp)3 did not shed additional light on this order of E states. Finally, it is concluded that the order of 4
T
1g and 2
T
2g cannot be decided from O
h crystal field calculations because of experimental uncertainties about choosing centers of gravity. In addition, 4
T
1g and 2
T
2g are close together so that ordering 2
E<4
E does not guarantee 2
T
2g<4
T
1g. However, it can be concluded that the ratio C/B4 is not correct, whereas the larger 7<(C/B)<8 is consistent with the data of all three molecules because of small B parameters ( 0.4). Locating OO transitions may somewhat decrease C/B and Dq.
Presented in part at the 161st American Chemical Society National Meeting, Los Angeles, California, March–April, 1971.
NDEA Pre-Doctoral Fellow. 相似文献
Zusammenfassung In der vorliegenden Arbeit werden folgende Meßergebnisse mitgeteilt; MCD, elektronische Absorption, Einfluß eines äußeren schweren Atoms sowie Kristallfelddaten für den Bereich niedriger Energie (2 E g, 2 T 1g, 4 T 2g) und den Bereich hoher Energie (2 T 2g, 4 T 1g) von Cr(dtp)3, Cr(dtc)3 und Cr(exan). Bei niedriger Energie sind die MCD-Intensitäten von 2 E(2 E g) und 2 E(2 T 1g) genau so groß, oder größer als 4 T 2g, und die MCD-Technik bietet Vorteile gegenüber der elektronischen Absorptionsmethode. Die MCD-Werte von 2 E g und 2 T 1g sind für die genannten Moleküle etwa gleich ( 13 kK und 13,6 kK). 4 T 2g dieses Gebietes erscheint trigonal aufgespalten ( 500 cm–1) bei MCD von dtp, aber in einem geringeren Maß als im elektronischen Kristallspektrum von Lebedda und Palmer ( 600 cm–1) MCD löste solche Komponenten bei exan und dtc nicht auf. Der Bereich höherer Energie enthält 2 T 2g und 4 T 1g, und aus der Kombination von Daten der MCD-Methode sowie der elektronischen Absorption schlossen wir auf die Anordnung 2 A 1g(2 T 2g)<2 E(2 T 2g)<4 E(4 T 1g). Der möglicherweise nützliche Effekt eines äußeren schweren Atoms auf die in Lösung beobachteten elektronischen 2 E- und 4E-Banden von Cr(dtp)3 brachte bezüglich dieser Anordnung der E-Zustände nichts Neues. Weiterhin wird gefolgert, daß die Ordnung von 4 T 1g und 2 T 2g nicht aus O h-Kristallfeldberechnungen entschieden werden kann, da experimentelle Unsicherheiten bezüglich der Wahl von Schwerpunkten bestehen. Außerdem liegen 4 T 1g und 2 T 2g nahe zusammen, sodaß aus der Anordnung 2 E<4 E nicht notwendig 2 T 2g<4 T 1g folgt. Es kann jedoch gefolgert werden, daß das Verhältnis C/B4 nicht korrekt ist, während 7<(C/B)<8 konsistent mit den Daten aller drei Moleküle ist, da die B-parameter klein sind (0,4). Die Vokalisierung der OO-Übergänge könnten C/B und Dq etwas erniedrigen.
Presented in part at the 161st American Chemical Society National Meeting, Los Angeles, California, March–April, 1971.
NDEA Pre-Doctoral Fellow. 相似文献
7.
Chemical syntheses of 2′-amino-2′-deoxyarabinonucleosides of uracil, thymine, cytosine, adenine, and guanine and their conversion into suitably protected 3′-phosphoramidite building blocks 24–28 for oligonucleotide synthesis are described. The 2-(4-nitrophenyl)ethoxycarbonyl (npeoc) group was used for protection of the aglycon and the 2′-amino functions. 相似文献
8.
A series of neutral porphyrin-containing catenanes has been synthesised, consisting of a zinc porphyrin strapped by a polyethylene glycol chain containing four or six ethylenoxy-units and incorporating a central naphthoquinol unit, interlinked with a naphthalene diimide macrocycle. The napthalene diimide precursor units exhibit only weak binding with the strapped porphyrins (Ka between 8 and 0.02 M(-1)), but good yields of the catenanes were obtained by Glaser coupling of the alkynyl napthalene diimide precursors in the presence of the porphyrins. Structures and solution conformations were determined by mass spectral and detailed 1H NMR studies. For the longer strapped porphyrins, the diimide macrocycle rotates around the central naphthoquinol unit at 420-450 times per second, while rotation is virtually prevented in the tighter strapped derivatives. A second dynamic process occurring in both sets of catenanes and described as 'yawing' leads to inequivalence in the naphthalene moieties. UV-Visible spectra indicate charge transfer interactions and electronic communication between the two components of the catenane. 相似文献
9.
Jäger D Seliger C Redpath NT Friedrich I Silber RE Pönicke K Werdan K Müller-Werdan U 《Electrophoresis》2000,21(13):2729-2736
Elongation factor 2 (EF-2) catalyses the last step of the elongation cycle, translocation, in the course of protein biosynthesis. A system for analyzing post-translational modifications of EF-2, which is a single polypeptide of 857 amino acids, is reported and its application to cytosolic extracts of cultured neonatal rat heart myocytes, neonatal and adult rat cardiac tissue, and extracts of human left ventricular myocardium is described. Comparing different pH ranges in immobilized pH gradient-isoelectric focusing (IPG-IEF), a range of pH 3 - 10 and 4 - 9 resulted in a highly defined and reproducible resolution of six different EF-2 variants of all extracts in the first dimension. These six variants were detected by the "imaging plate" (phosphor radiation image sensor) after specific labeling with Pseudomonas exotoxin A catalyzed [32P]ADP-ribosylation. This finding could be confirmed in Western blot analysis with a specific polyclonal rabbit antibody. Using two-dimensional polyacrylamide gel electrophoresis (2-D-PAGE), five to six EF-2 variants could be demonstrated in all extracts. By application of a second IPG indicator strip to the 2-D gel, they could be aligned with corresponding spots in a silver-stained 2-D separation of human myocardial tissue, revealing that the EF-2 variants belong to the group of low-abundance proteins. 相似文献
10.
Low-energy coherent charge-density wave excitations are investigated in blue bronze (K(0.3)MoO(3)) and red bronze (K(0.33)MoO(3)) by femtosecond pump-probe spectroscopy. A linear gapless, acousticlike dispersion relation is observed for the transverse phasons with a pronounced anisotropy in K(0.33)MoO(3). The amplitude mode exhibits a weak (opticlike) dispersion relation with a frequency of 1.67 THz at 30 K. Our results show for the first time that the time-resolved optical technique provides momentum resolution of collective excitations in strongly correlated electron systems. 相似文献