The main purpose of this paper is clarifying the connection between some characteristics of a deciding body and the probability of its making correct decisions. In our model a group of decision makers is required to select one of two alternatives. We assume the probabilities of the decision makers being correct are independent random variables distributed according to the same given distribution rule. This distribution belongs to a general family, containing the uniform distribution as a particular case. We investigate the behavior of the probability of the expert rule being optimal, as well as that of the majority rule, both as functions of the distribution parameter and the group size. The main result is that for any value of the distribution parameter the expert rule is far more likely to be optimal than the majority rule, especially as the deciding body becomes larger. 相似文献
Analytical expressions for neutron reflection and transmission by magnetic mirrors with helical magnetization are derived. Reflectance curves with and without neutron spin flip are presented. Resonant properties of helical systems are studied. 相似文献
The crystal structure of a series of thienylgermatranes has been studied using X-ray diffraction. Disorder of the thiophene
ring in a 2-thienylgermatrane has been established. In the same positions of the unit cell of the crystal there are found
both molecules with an O(2)-Ge-C-S torsional angle of −166.8(4)° and molecules in which this angle is 14.0(4)°. The lengths
of the transannular N→Ge bonds (2.183–2.283 Å) agrees in value with the values of crystalline germatrane structures with a
Ge-C bond. The length of the transannular N→Ge bond (2.248 Å) in 4-(2-thienyl)phenylgermatrane (molecule A) is the largest
amongst germatranes with a Ge-Car bond. Introduction of a second thiophene ring into the 2-thienylgermatrane molecule lowers the acute toxicity of the compound
by about 27 times (LD50 for the 2,2′-bithienylgermatrane = 447 mg/kg).
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Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 299–306, February, 2007. 相似文献
Trihalogermyl-furans and -thiophenes were prepared by inserting germanium dibromide (GeBr2) generated from the dibromogermane(II) dioxanate complex into the carbon-halogen bond of halo-furans and -thiophenes. Their ethanolysis and transesterification by triethanolamine yielded the germatranes which were subjected to psychotropic activity assays. The psychotropic properties of germatranes were found to depend on the type of the heterocycle and on the position of the germatrane moiety. 相似文献
Triethylbenzylammonium chlorometallates [Et3NCH2Ph][MCln]m? (M = Pt, Pd, Rh, Ir, Fe, Co, Cu, m = 1–3, n = 3–6), polymer-anchored ionic metal complexes [?—CH2PBu3][MCln]n? and some other chlorometallates and complexes of platinum, rhodium, ruthenium and osmium were studied as catalysts in the hydrogermylation of phenylacetylene with triethylgermane. All the complexes containing platinum, palladium and rhodium were found to be effective catalysts. The cis/trans ratio of the products obtained is determined by the metal atom involved and decreases in the following order: Ir > Rh ? Pd > Pt. 相似文献
A new method was developed for the synthesis of silicon-and germanium-containing acetylfurans and acetylthiophene by metallation
of 2-acetylfuran or 2-acetylthiophene with n-BuLi at low temperature after protection of the carbonyl group with lithium N-methylpiperazide
and reaction of the lithium derivative with various trialkyl-, alkylphenyl-, and cycloalkylchlorosilanes or trialkylchloro(bromo)germanes.
The cytotoxic activity of the new compounds was studied, and it was established that the silicon-and germanium-containing
acetylfurans and acetylthiophenes are substances with low toxicity (LD50 312->2000 mg/kg) and have low cytotoxicity toward HT-1080 and MG-22A tumor cells.
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Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 192–199, February, 2007. 相似文献
Abstract Different methods for the determination of the local field anisotropy in liquid crystals are analysed and the problems resulting from their application are outlined. One such method, namely that based on the comparison of the polarization of resonance Raman scattering and absorption bands is studied in more detail. The method is applied to determine the structural anisotropy for the 4-n-pentyl-(4′-cyanophenyl) derivatives of benzene, cyclohexane and bicyclooctane. To account for the difference between the optical properties of the probe and of the solvent at the wavelength of the scattered light the local field factor is treated theoretically within the framework of an anisotropic continuous dielectric medium. 相似文献
The reaction of 1,2-phenylenediamine with a variety of silicon- or germanium-containing 2-furaldehydes or 2-thienylcarbaldehydes in DMFA gave the corresponding benzimidazole derivatives in moderate yields (36–49%) in the presence of sodium hydrogen sulfite. As a result, a new series of silyl, germyl substituted hetarylbenzimidazoles were synthesized and their in vitro cytotoxicity was studied. The quaternisation of N-substituted benzimidazoles by heating with various alkyl, allyl and propargyl chlorides and bromides leads to the formation of benzimidazolinium salts. Potential cytotoxic activity of synthesized new benzimidazoles and benzimidazolinium salts was tested in vitro on two monolayer tumour cell lines: MG-22A (mouse hepatoma), HT-1080 (human fibrosarcoma) and normal mouse fibroblasts (NIH 3T3) and compared with corresponding benzimidazoles. 相似文献