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1.
It is well known from work of Bruhat and Tits that an affinebuilding has a spherical building at infinity. The paper studiesthe structure at infinity for an affine twin building. It isshown that the twinning restricts the structure at infinityin a natural way, producing two smaller spherical buildingsthat are canonically isomorphic to one another. In the processit is shown that to each wall and panel of these buildings atinfinity is attached a twin tree. 相似文献
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As ab initio electronic structure calculations become more accurate, inherent sources of error in classical transition state theory such as barrier recrossing and tunneling may become major sources of error in calculating rate constants. This paper introduces a general method for diabatically constructing the transverse eigensystem of a reaction path Hamiltonian in systems with many degenerate transverse frequencies. The diabatically constructed reaction path Hamiltonian yields smoothly varying coupling constants that, in turn, facilitate reactive flux calculations. As an example we compute the dynamically corrected rate constant for the chair to boat interconversion of cyclohexane, a system with 48 degrees of freedom and a number of degenerate frequencies. The transmission coefficients obtained from the reactive flux simulations agree with previous results that have been calculated using an empirical potential. Furthermore, the calculated rate constants agree with experimental values. Comparison to variational transition state theory shows that, despite finding the true bottleneck along the reaction pathway, variational transition state theory only accounts for half of the rate constant reduction due to recrossing trajectories. 相似文献
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Desmet G Vervoort N Clicq D Huau A Gzil P Baron GV 《Journal of chromatography. A》2002,948(1-2):19-34
It is only by developing specially designed injection and detection systems that shear-driven chromatography can become a viable alternative to HPLC. In the present paper, a dedicated zero dead-volume injection procedure is presented with which sample volumes can be injected reproducibly in the required picoliter range. In addition, a transversal detection groove system is designed which should allow to perform on-line UV-VIS absorption measurements with path lengths in the millimeter range, with an acceptable theoretical plate loss (only 20% in a 5 cm long channel) and acting as a nearly perfect wave guide. 相似文献
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Studies on the capacity of Pr in uitro to photoconvert to the long wavelength in uioo-like Pfr form were performed with extracts from 10 species. Red irradiation, immediately after extraction of crude extracts from 9 species, photoconverted Pr to long-wavelength Pfr with an absorbance maximum around 735 nm. Red irradiation of soybean extracts, however, photoconverted Pr to short-wavelength Pfr, with an absorbance maximum at 725 nm. Red irradiation given later than 1.5-2 h after extraction, to extracts of oats, pea, cucumber, radish, sunflower and soybean, photoconverted Pr to a short-wavelength Pfr species with an absorbance maximum around 725 nm. In crude extracts of barley, corn, wheat and zucchini, red irradiation, even after a long dark-incubation period at 4°C of up to 48 h, photoconverted Pr to long-wavelength Pfr with an absorbance maximum around 735 nm. After incubation at 25°C for 3 h, however, Pr from barley also photoconverted to the short-wavelength form. It is suggested that in the group exemplified by oats, Pr rapidly undergoes an alteration following extraction, which results in the loss of the capacity of Pr to photoconvert to long-wavelength Pfr. In contrast, in extracts from the group exemplified by barley, Pr is much more stable and retains the capacity to photoconvert to long-wavelength Pfr for much longer periods. 相似文献
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The microwave spectrum of the main isotopic species of cyclopentadienone has been measured and assigned. The rotational constants imply an essentially planar geometry and that the ring is rather “fatter” than the analogous ring in fulvene.The dipole moment, derived from Stark-effect measurements, is 10.4 × 10?30 C m (3.13 D). A vibrational satel- lite spectrum, which, from its inertial defect, corresponds to an out-of-plane vibration has also been assigned.The life time of cyclopentadienone under our spectroscopic conditions is approximately 15 sec. 相似文献
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Summary AssumeE is a real topological vector space,F is a real Banach space,K is a discrete subgroup ofF andC is a symmetric, convex and compact subset ofF such thatK (6C) = {0}. If a functionh:E F is continuous at at least one point andh(x + y) – h(x) – h(y) K + C for allx, y E, then there exists a continuous linear functiona:E F such thath(x) – a(x) K + C for everyx E. 相似文献
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Aihara H Alston-Garnjost M Bakken JA Barbaro-Galtieri A Barnes AV Barnett BA Bengtsson H Blumenfeld BJ Bross AD Buchanan CD Chamberlain O Chien C Clark AR Cordier A Dahl OI Day CT Derby KA Eberhard PH Fancher DL Fujii H Fujii T Gabioud B Gary JW Gorn W Hadley NJ Hauptman JM Hofmann W Huth JE Hylen J Kamae T Kaye HS Kenney RW Kerth LT Koda RI Kofler RR Kwong KK Layter JG Lindsey CS Loken SC Lu X Lynch GR Madansky L Madaras RJ Maruyama K Marx JN Matthews JA Melnikoff SO Moses W Nemethy P 《Physical review letters》1985,54(4):270-273