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121.
Jean Bourgain 《Communications in Mathematical Physics》1996,176(2):421-445
Consider the2D defocusing cubic NLSiu
t+u–u|u|2=0 with Hamiltonian
. It is shown that the Gibbs measure constructed from the Wick ordered Hamiltonian, i.e. replacing ||4 by ||4 :, is an invariant measure for the appropriately modified equationiu
t
+ u‒ [u|u
2–2(|u|2
dx)u]=0. There is a well defined flow on thesupport of the measure. In fact, it is shown that for almost all data the solutionu, u(0)=, satisfiesu(t)–e
it C
Hs
(), for somes>0. First a result local in time is established and next measure invariance considerations are used to extend the local result to a global one (cf. [B2]). 相似文献
122.
Jean Calbrix 《Transactions of the American Mathematical Society》1996,348(5):2085-2090
We say that a countable, Hausdorff, topological space with one and only one accumulation point is a point-space. For such a space, we give several properties which are equivalent to the property of being a k-space. We study some free filters on the set of integers and we determine if the associated point-spaces are k-spaces or not. We show that the filters of Lutzer-van Mill-Pol are k-filters. We deduce that, for each countable ordinal , there exists a free filter of true additive class (Baire's classification) and a free filter of true multiplicative class for which the associated point-spaces are k-spaces but not , the existence being true in the additive case for . In particular, we answer negatively a question raised in J. Calbrix, C. R. Acad. Sci. Paris 305 (1987), 109--111.
123.
Jean Bénabou 《Applied Categorical Structures》1996,4(2-3):139-165
We give necessary and sufficient conditions on class S of maps of a category C so that a good calculus of fractions is possible in C[S
-1], and a geometric characterization of the communitative diagrams in the category of fractions. These conditions are also described simply in terms of Grothendiek topologies.We characterize the categories which arise in this manner by the fact that the functor C C[S
-1] is uniformly flat and give some applications of this result. 相似文献
124.
Two Fraenkel-Mostowski models are constructed in which the Boolean Prime Ideal Theorem is true. In both models, AC for countable sets is true, but AC for sets of cardinality 2 and the 2m = m principle are both false. The Principle of Dependent Choices is true in the first model, but false in the second. Mathematics Subject Classification: 03E25, 03E35, 04A25. 相似文献
125.
The multicritical points of the O(N)-invariant N vector model in the large-N limit are re-examined. Of particular interest are the subtleties involved in the stability of the phase structure at critical dimensions. In the limit N → ∞ while the coupling g → gc in a correlated manner (the double scaling limit) a massless bound state O(N) singlet is formed and powers of 1/N are compensated by IR singularities. The persistence of the N → ∞ results beyond the leading order is then studied with particular interest in the possible existence of a phase with propagating small mass vector fields and a massless singlet bound state. We point out that under certain conditions the double scaled theory of the singlet field is non-interacting in critical dimensions. 相似文献
126.
Jean Barge 《K-Theory》1993,7(1):9-16
In this paper we construct a canonical 2-cocycle on the groupP SL(2,k) with values in the Witt groupW(k) of the fieldk. This allows us to produce anatural homomorphism :H
2(SL(2,k); Z)I
2(k), whereI
2(k) is the square of the fundamental ideal. We prove that this homomorphism is in fact a lift of Milnor's symbol. 相似文献
127.
The development of a one-pot tandem intramolecular conjugate addition/nucleophilic acyl substitution using samarium(II) iodide is reported. The reaction relies on the reagent’s unique ability to mediate both radical and anionic pathways, which are likely integral to the mechanism of this transformation. The tricyclic hemiacetal product was formed in good yield, with excellent diastereoselectivity, and its structure was verified by X-ray crystallographic analysis. 相似文献
128.
The photosulfochlorination of n-tetradecane by sulfuryl chloride leads to a reaction mixture containing unreacted n-tetradecane, chloro n-tetradecanes and n-tetradecanesulfonyl chlorides. Direct and simultaneous GC analysis of the mixture of the sulfochlorinated and chlorinated isomers is followed by mass spectrometry identification of all the components either by electron impact (EI-MS) and by negative and positive chemical ionisation (NCI-MS and PCI-MS). With the goal of performing an accurate quantitative GC analysis, and as n-tetradecanesulfonyl chlorides prone to degrade partially into the corresponding chlorides, the former are converted to N,N-diethylsufonamides, more stable thermally, and then analysed by GC/EI-MS and GC/PCI-MS. The chloro n-tetradecanes, sulfonylchlorides and sulfonamides spectra present strong similarities. However, some differences between terminal and internal isomers are noticed and the peculiar behaviour of sulfonamides is emphasized. 相似文献
129.
The addition of the dianion of Johnson’s sulfoximine to α,ω-halogenoesters evolves by an intramolecular heterocyclization to provide a direct access to 2-alkylidenetetrahydrofurans bearing a chiral sulfur atom via domino addition-elimination/SN reactions. 相似文献
130.
Jacques Lievin Jacques Breulet Philippe Clercq Jean -Yves Metz 《Theoretical chemistry accounts》1982,61(6):513-537
A simplified method of determining the molecular correlation energy by two separate calculations, one for the internal and
one for the non-internal correlation energies, is extended to multiconfigurational zeroth-order wavefunctions. This extension
offers the possibility of deriving correlated potential energy curves or surfaces for processes involving configurational
changes. The internal correlation energy is shown to be correctly determined by an MC/CI procedure combining the use of minimal
and extended basis sets. An original semi-empirical “atoms-in-molecules” method based on the L.C.A.O. expansion of the molecular
wavefunction is proposed for the non-internal correlation energy calculations. This method is shown to be able to overcome
some of the shortcomings of a previous populations analysis approach. Test calculations concern potential curve parameters
(D
e
,T
e
,R
e
,W
e
) of the ground and some excited states of the NH, C2, HCN and CN molecules. The results are found to be in good agreement with corresponding experimental and large CI results.
Aspirant du Fonds National Belge de la Recherche Scientifique
Boursier I.R.S.I.A. 相似文献