Error Control in Convergence Acceleration Processes

A procedure for estimating the error on the transformed sequenceobtained by a convergence acceleration method is given. Theprocedure generates a sequence of intervals which asymptoticallycontain the limit of the sequence to be accelerated. The procedureis used to construct a test for the automatic selection of asequence transformation among several others. Theoretical resultson this selection method are proved. Numerical results illustratethe procedures. ^*Work performed under the NATO Research Grant 027–81.     

Complete characterization of the water dimer vibrational ground state and testing the VRT(ASP-W)III,SAPT-5st,and VRT(MCY-5f) surfaces

We report the observation of extensive a- and c-type rotation-tunnelling (RT) spectra of (H₂O)₂ for K_a = 0–3, and (D₂O)₂ for K_a = 0–4. These data allow a detailed characterization of the vibrational ground state to energies comparable to those of the low-lying (70–80 cm^?1) intermolecular vibrations. We present a comparison of the experimentally determined molecular constants and tunnelling splittings with those calculated on the VRT(ASP-W)III, SAPT-5st, and VRT(MCY-5f) intermolecular potential energy surfaces. The SAPT-5st potential reproduces the vibrational ground state properties of the water dimer very well. The VRT(MCY-5f) and especially the VRT(ASP-W)III potentials show larger disagreements, in particular for the bifurcation tunnelling splitting.     

ABSORPTION AND FLUORESCENCE SPECTRA OF CHLOROPHYLL-a IN POLAR SOLVENTS AS A FUNCTION OF TEMPERATURE

Abstract— Absorption and fluorescence spectra of chlorphyll-a in aqueous alcohol were determined as a function of temperature between 173° and 293°K. From a comparison of these spectra with ones obtained in pure methanol, it is suggested that changes in molecular association occur within aggregates of chlorophyll-a in aqueous-alcoholic solution induced by variation of the dielectric constant. The latter varies over a wide range in aqueous alcohol as a function of temperature.     

PHOTODYNAMIC INHIBITION OF ESCHERICHIA COLI DNA POLYMERASE I BY 8-METHOXYPSORALEN PLUS NEAR ULTRAVIOLET IRRADIATION

Abstract— Morphological abnormality due to the UV irradiation of sperm and its modification by photoreactivation (PR) were studied in the sea urchin, Hemicentrotus pukherrimus. When sperm was UV-irradiated and allowed to fertilize unirradiated eggs, the effect of the UV was manifested as an abnormal morphology of embryos in the gastrula or later stages. The UV-induced morphological abnormality was prevented by photoreactivation when the fertilized eggs were illuminated with visible light. In the experiments on a stage-dependent change of PR effectiveness, it was found that an illumination sufficed to effect a nearly complete PR when applied up to the onset of the first DNA synthetic phase, while the PR effectiveness declined thereafter. Illumination after the completion of DNA synthesis had little effect for PR.     

FLUORESCENCE ENERGY TRANSFER BETWEEN DIMETHYLDIAZAPEROPYRENIUM DICATION AND ETHIDIUM INTERCALATED IN POLY d(A-T)

Dimethyldiazaperopyrenium is one of the largest known DNA intercalators. Fluorescence energy transfer occurred between dimethyldiazaperopyrenium (donor) and ethidium (acceptor) when these dyes were bound to a double-stranded polynucleotide such as poly d(A-T). The addition of increasing amounts of ethidium bromide led to a marked shortening of the fluorescence lifetime of the donor, whereas the excited state of the acceptor was progressively populated via energy transfer from the donor. Critical Förster distance between these two chromophores was calculated to be 3.8 nm. The observed transfer efficiency was lower than that calculated on the basis of this critical distance and a statistical distribution of bound drugs. These results are discussed taking into account the conformational change induced by intercalation of dimethyldiazaperopyrenium in the double-stranded polynucleotide.     

有向完美图

Gallai 和 Milgram 曾经证明,有向图 G 的所有结点可用恰好 α(G) 条互不相交的路来复盖,此处 α(G) 为图 G 的内固数.然而这个结果的好多证明都未指出存在着一最优 内固集 S 以及结点集的一个路剖分 μ_1,μ_2,…μ_k,以致对于所有 i,均有|S∩μ_i|=1.Gallai 和 Roy 曾经独立地证明,在一有向图 G 中,令 k 为一条路所能包含的最多的结点的个数,则 k 至少等于图 G 的色数γ(G).同样,我们不知道是否存在一最优色谱(S_1,S_2,…,S_k)以及一条路μ,以致对于所有的 i,均有|S_i∩μ|=1.在本文中引进了下述概念:1.有向图 G 称为α-有向完美,若对于每一最优内固集 S,均存在结点集合的一个路剖分μ_1,μ_2,…,以致对于所有的 i,均有|S∩μ_i|=1(且此性质对 G 的任一子图亦成立).2.一有向图 G 称为 γ-完美,若对于每一最优色谱 (S_1,S_1,…S_k),均存在一条路 μ,以致对于所有 i,均有|μ∩S_i|=1(且此性质对 G 的每一子图亦均成立).3.一长度为2k+1的奇圈系由2k+1条弧 u_1,u_2,…,u_(2k+1) 所给出,并从而确定了一个有2k+1个结点的序列 x_1,x_2,…,x_(2k+1).一条弦,可以是 G 的一条弧,它联结在以上叙列中不相继的两个结点,或者是 G 的一条弧,它平行上述2k+1条弧中的一条弧.一个奇圈称为反有向的,若i)其长度>3,ii)最长     

A graphical procedure for an on-condition maintenance policy: imperfect-inspection model and interpretation

This paper considers on-condition maintenance based on periodicinspection and control of a condition parameter which describesthe wear and deterioration of the productive equipment. We developa model based on delay time and imperfect inspection, and builda graphical procedure to choose the best inspection intervalfor different criteria. The interpretation of this graphicalprocedure allows us to emphasize the factors that are relevantfor inspection decision-making.     

PHOTOCHEMICAL REACTIONS OF PYRIMIDINE DERIVATIVES WITH ACRYLONITRILE IN AQUEOUS SOLUTIONS

Abstract— Ultraviolet excitation of pyrimidine derivatives in aqueous solutions containing acrylonitrile can lead to polymerisation of acrylonitrile and/or photoaddition reactions of acrylonitrile and the pyrimidine. Polymerisation of acrylonitrile induced by excitation of orotic acid occurs even in aerated solutions and is very likely due to radicals derived from excited orotic acid molecuies. Using ¹⁴C-labelied orotic acid, the polymer is shown to contain the pyrimidine. With other pyrimidine derivatives, polymerisation is observed only in deaerated solutions and its low yield did not allow us to determine whether the polymerisation is induced by radicals or by photosensitisation. The role of the lowest excited singlet and triplet states of the pyrimidine derivatives in the photoaddition reaction is discussed. In the case of orotic acid, photoaddition is shown to proceed entirely by way of the triplet state.     

Extension of the Virasoro and Neveu-Schwarz Algebras and Generalized Sturm-Liouville Operators

We consider the universal central extension of the Lie algebra Vect(S ¹) C(S ¹). The coadjoint representation of thisLie algebra has a natural geometric interpretation by matrix analogues ofthe Sturm –Liouville operators. This approach leads to new Liesuperalgebras generalizing the well-known Neveu –Schwarz algebra.