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71.
In this note, we study non-linear gauge theories for principal bundles, where the structure group is replaced by a Lie groupoid. We follow the approach of Moerdijk–Mr?un and establish its relation with the existing physics literature. In particular, we derive a new formula for the gauge transformation which closely resembles and generalizes the classical formulas found in Yang Mills gauge theories. 相似文献
72.
[reaction: see text]. Mass spectral data are presented indicating that the antitumor agent 2-crotonyloxymethyl-2-cyclohexenone (COMC) is capable of alkylating oligonucleotides via a mechanism involving an electrophilic exocyclic enone intermediate. Under physiological conditions, the exocyclic enone is likely the glutathionylated 2-exomethylenecyclohexenone. This supports a recent hypothesis that the antitumor activity of COMC arises from alkylation of nucleic acids and/or proteins critical to cell function and not from competitive inhibition of glyoxalase I by an adduct of COMC and glutathione. 相似文献
73.
74.
The reaction of ferrocenylmethylcarbocations with the ambident thiocyanate ion produces only the isothiocyanate isomer. 相似文献
75.
Daniele Mundici 《Archive for Mathematical Logic》1983,23(1):27-36
For any sentenceα (in sentential logic) letd α be the delay complexity of the boolean functionf α represented byα. We prove that for infinitely manyd (and starting with somed<620) there exist valid implicationsα→β withd α,d β≦d such that any Craig's interpolantx has its delay complexityd χ greater thand+(1/3)·log(d/2). This is the first (non-trivial) known lower bound on the complexity of Craig's interpolants in sentential logic, whose general study may well have an impact on the central problems of computation theory. 相似文献
76.
Dell'Orco D Seeber M De Benedetti PG Fanelli F 《Journal of chemical information and modeling》2005,45(5):1429-1438
Fragment complementation is gaining an increasing impact as a nonperturbing method to probe noncovalent interactions within protein supersecondary structures. In this study, the fast Fourier transform rigid-body docking algorithm ZDOCK has been employed for in silico reconstitution of the calcium binding protein calbindin D9k, from its two EF-hands subdomains, namely, EF1 (residues 1-43) and EF2 (residues 44-75). The EF1 fragment has been used both in its wild type and in nine mutant forms, in line with in vitro experiments. Consistent with in vitro data, ZDOCK reconstituted the proper fold of wild-type and mutated calbindin, locating the nativelike structures (i.e., holding a root-mean-square deviation < 1 A with respect to the X-ray structure) among the first 10 top-scored solutions out of 4000. Moreover, the three independent in silico reconstitutions of wild-type calbindin ranked a nativelike structure at the top of the output list, that is, the best scored one. The algorithm has been also successfully challenged in reconstituting the EF2 homodimer from two identical copies of the monomer. Furthermore, quantitative models consisting of linear correlations between thermodynamic data and ZDOCK scores were built, providing a tested tool for very fast in silico predictions of the free energy of association of protein-protein complexes solved at the atomic level and known to not undergo significant conformational changes upon binding. 相似文献
77.
We study the kinetics of crystal nucleation of an undercooled Lennard-Jones liquid using various path-sampling methods. We obtain the rate constant and elucidate the pathways for crystal nucleation. Analysis of the path ensemble reveals that crystal nucleation occurs along many different pathways, in which critical solid nuclei can be small, compact, and face centered cubic, but also large, less ordered, and more body centered cubic. The reaction coordinate thus includes, besides the cluster size, also the quality of the crystal structure. 相似文献
78.
Partially dynamic maintenance of minimum weight hyperpaths 总被引:1,自引:0,他引:1
Giorgio Ausiello Paolo Giulio Franciosa Daniele Frigioni 《Journal of Discrete Algorithms》2005,3(1):27-46
We address the problem of dynamically maintaining minimum weight hyperpaths in a directed hypergraph in a decremental setting. For such a problem, we provide a new efficient algorithm that works for a wide class of hyperpath weight measures. This algorithm explicitly updates minimum weight hyperpaths in
worst case time under a sequence of L hyperarc weight increments and hyperarc deletions, where C is the maximum weight of minimum hyperpaths in
and
is the size of the representation of the hypergraph. Hyperpath weight measures are only required to belong to the class of strict weakly superior functions. 相似文献
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79.
Nonlinear losses accompanying self-focusing substantially impact the dynamic balance of diffraction and nonlinearity, permitting the existence of localized and stationary solutions of the 2D + 1 nonlinear Schr?dinger equation, which are stable against radial collapse. These are featured by linear, conical tails that continually refill the nonlinear, central spot. An experiment shows that the discovered solution behaves as a strong attractor for the self-focusing dynamics in Kerr media. 相似文献
80.
Benati L Calestani G Leardini R Minozzi M Nanni D Spagnolo P Strazzari S 《Organic letters》2003,5(8):1313-1316
[reaction: see text] The radical chain reaction of benzenethiol with alkynylthiol esters provides a new, valuable protocol for the tin-free generation of acyl radicals that arise from intramolecular substitution at sulfur by the initial sulfanylvinyl radicals. 相似文献