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211.
In our simplicial version of lattice gauge theory, we approximate Euclidean path integrals by tiling space-time with simplexes
and by linearly interpolating the fields throughout each simplex from their values at the vertices. We compare this method
with Wilson's lattice gauge theory forU(1) in three dimensions. As a standard of comparison, we compute the exact values of Creutz ratios of Wilson loops in the
continuum theory. Monte Carlo computations using the simplicial method give Creutz ratios within a few percent of the exact
values for reasonably sized loop atβ=1, 2, and 10. Similar computations using Wilson's method give ratios that typically differ from the exact values by factors
of 2 or more for 1⩽β⩽3.5 and that have the wrongβ dependence. The better accuracy of the simplicial method is due to its use of the action and domain of integration of the
exact theory, unaltered apart from the granularity of the simplicial lattice. We also present data on the action density and
the mass gap.
Research supported by the U.S. epartment of Energy under grant DE-FG04-84ER40166. 相似文献
212.
Ballagh HC Bingham HH Lawry TJ Lys J Lynch GR Sokoloff MD Stevenson ML Huson FR Schmidt E Smart W Treadwell E Cence RJ Harris FA Jones MD Koide A Peters MW Peterson VZ Lubatti HJ Moriyasu K Wolin E Camerini U Fry W Gee D Gee M Loveless RJ Reeder DD 《Physical review D: Particles and fields》1989,40(9):2764-2771
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215.
[structure: see text] The synthesis of a photoaffinity probe for EGFR is described. O-Alkylation of 4-(meta-azidoanilino)-6-methoxy-7-hydroxy-quinazoline with a protected tetraethyleneglycol linker followed by the attachment of tetramethylrhodamine yielded the fluorescent probe AX7593. Photoaffinity labeling of EGFR by AX7593 (K(b) = 280 nM) was shown to have an efficiency of 34% and to be competitive with the EGFR inhibitors PP2 and AG1478. 相似文献
216.
Amino sugar has been synthesized in racemic form as a mixture of anomers from sorbic aldehyde. An intramolecular N-sulfinyl dienophile Diels-Alder strategy was used to stereospecifically generate the chiral centers of pentose . 相似文献
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Athanassopoulos C Auerbach LB Burman RL Cohen I Caldwell DO Dieterle BD Donahue JB Eisner AM Fazely A Federspiel FJ Garvey GT Gray M Gunasingha RM Imlay R Johnston K Kim HJ Louis WC Majkic R Margulies J McIlhany K Metcalf W Mills GB Reeder RA Sandberg V Smith D Stancu I Strossman W Tayloe R VanDalen GJ Vernon W Wadia N Waltz J Wang YX White DH Works D Xiao Y Yellin S 《Physical review letters》1996,77(15):3082-3085
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220.
The thiazolidine, 1-thia-4-azaspiro[4,5] decane (Ia), which is derived from cyclohexanone and 2-aminoethanethiol (X), forms a thiazolidone (VIII) with mercaptoacetic acid more slowly and in lower yield than with 2-phenylthiazolidine, a case reported previously. A thiazolidine which is related to a non-conjugate chain tautomer such as Ic, might be expected to behave in this way. Alkylation, as another possible example of tautomer chemistry, was studied, and N-, S-, and C-alkylation were all observed under varying circumstances. Thus, thiazolidine la undergoes alkylation with methyl iodide in ethanol to form the N-methylthiazolidine (IIa), and in sodium-liquid ammonia to give the S-methyl derivative (III). In the latter case, alkylation occurs with reductive cleavage. Although no trace of other tautomer derivatives (IV, V) was to be found in the methyl iodide alkylation, I with acrylonitrile did in fact give C-alkylation. An analytically pure mixture of tautomers was obtained, from which 2-oxocyclohexanepropionitrile (VI) was isolated on hydrolysis. In a manner similar to the formation of III, IIa was S-alkylated by treatment with sodium-liquid ammonia followed by benzyl chloride to give a saturated product (XVII). Although such a process might be identified with a chain tautomer (IIb), the evidence is to the contrary, since the intermediate (XIV), which might be involved in such a process, fails to undergo a similar reduction with sodium-liquid ammonia. A greatly improved procedure for the preparation of thiazolidine (XI, 86% yield) is also reported. 相似文献