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831.
Molina JJ Lectez S Tazi S Salanne M Dufrêche JF Roques J Simoni E Madden PA Turq P 《The Journal of chemical physics》2011,134(1):014511
Dipole polarizabilities of a series of ions in aqueous solutions are computed from first-principles. The procedure is based on the study of the linear response of the maximally localized Wannier functions to an applied external field, within density functional theory. For most monoatomic cations (Li(+), Na(+), K(+), Rb(+), Mg(2+), Ca(2+) and Sr(2+)) the computed polarizabilities are the same as in the gas phase. For Cs(+) and a series of anions (F(-), Cl(-), Br(-) and I(-)), environmental effects are observed, which reduce the polarizabilities in aqueous solutions with respect to their gas phase values. The polarizabilities of H((aq)) (+), OH((aq)) (-) have also been determined along an ab initio molecular dynamics simulation. We observe that the polarizability of a molecule instantaneously switches upon proton transfer events. Finally, we also computed the polarizability tensor in the case of a strongly anisotropic molecular ion, UO(2) (2+). The results of these calculations will be useful in building interaction potentials that include polarization effects. 相似文献
832.
For graphs of bounded maximum average degree, we consider the problem of 2‐distance coloring, that is, the problem of coloring the vertices while ensuring that two vertices that are adjacent or have a common neighbor receive different colors. We prove that graphs with maximum average degree less than and maximum degree Δ at least 4 are 2‐distance ‐colorable, which is optimal and improves previous results from Dolama and Sopena, and from Borodin et al. We also prove that graphs with maximum average degree less than (resp. , ) and maximum degree Δ at least 5 (resp. 6, 8) are list 2‐distance ‐colorable, which improves previous results from Borodin et al., and from Ivanova. We prove that any graph with maximum average degree m less than and with large enough maximum degree Δ (depending only on m) can be list 2‐distance ‐colored. There exist graphs with arbitrarily large maximum degree and maximum average degree less than 3 that cannot be 2‐distance ‐colored: the question of what happens between and 3 remains open. We prove also that any graph with maximum average degree can be list 2‐distance ‐colored (C depending only on m). It is optimal as there exist graphs with arbitrarily large maximum degree and maximum average degree less than 4 that cannot be 2‐distance colored with less than colors. Most of the above results can be transposed to injective list coloring with one color less. 相似文献
833.
Abdênago Barros Cícero Aquino Henrique de Lima 《Annali di Matematica Pura ed Applicata》2014,193(3):689-698
Our purpose is to study the rigidity of complete hypersurfaces immersed into a Riemannian space form. In this setting, first we use a classical characterization of the Euclidean sphere \(\mathbb S ^{n+1}\) due to Obata (J Math Soc Jpn 14:333–340, 1962) in order to prove that a closed orientable hypersurface \(\Sigma ^n\) immersed with null second-order mean curvature in \(\mathbb S ^{n+1}\) must be isometric to a totally geodesic sphere \(\mathbb S ^{n}\) , provided that its Gauss mapping is contained in a closed hemisphere. Furthermore, as suitable applications of a maximum principle at the infinity for complete noncompact Riemannian manifolds due to Yau (Indiana Univ Math J 25:659–670, 1976), we establish new characterizations of totally geodesic hypersurfaces in the Euclidean and hyperbolic spaces. We also obtain a lower estimate of the index of minimum relative nullity concerning complete noncompact hypersurfaces immersed in such ambient spaces. 相似文献
834.
Michel Chipot Francisco Julio S. A. Corrêa 《Bulletin of the Brazilian Mathematical Society》2009,40(3):381-393
The goal of this paper is to study a class of nonlinear functional elliptic equations using very simple comparison principles.
We first construct a nontrivial solution and then study its asymptotic behaviour when the diffusion coefficient goes to 0. 相似文献
835.
Mayerhoff Zea D. V. L. Roberto Inês C. Franco Telma T. 《Applied biochemistry and biotechnology》2001,91(1-9):729-737
Xylose reductase (XR) activity was evaluated in extracts of Candida mogii grown in media containing different concentrations of rice straw hydrolysate. Results of X Ractivity were compared to xylitol
production and a similar behavior was observed for these parameters. Highest values of specific production and productivity
were found for xylose reductase (35 U/g of cell and 0.97 U/[g of cell·h], respectively) and for xylitol (5.63 g/g of cell
and 0.13 g/[g of cell·h]) in fermentation conducted in medium containing 49.2 g of xylose/L. The maximum value of XR:XD ratio
(1.82) was also calculated under this initial xylose concentration with 60 h of fermentation. 相似文献
836.
Awafo Victor A. Chahal Devinder S. Simpson Ben K. Lê George B. B. 《Applied biochemistry and biotechnology》1996,57(1):461-470
Applied Biochemistry and Biotechnology - Three mutants ofTrichoderma reesei were grown in solid-state fermentation (SSF) in flasks and in a pan bioreactor. Mutant strain MCG 80 proved to be best at... 相似文献
837.
Sebastiāo C. de Almeida Aldir Brasil Jr. Luiz Amâncio M. Souza Jr. 《Results in Mathematics》2004,46(1-2):1-9
Let M be a compact, minimal 3-dimensional submanifold with constant scalar curvature R immersed in the standard sphere S3+p. In codimension 1, we know from the work that has been done on Chern’s conjecture that M is isoparametric and R = 3D0, R = 3D3 or R = 3D6. In this paper we extend this result from codimension one to compact submanifolds with a flat normal bundle and give a complete classification. 相似文献
838.
C. Finck O. Stézowski F.A. Beck D.E. Appelbe T. Byrski S. Courtin D.M. Cullen D. Curien G. de France G. Duchêne S. Ertürk B.J.P. Gall U. Garg B. Haas N. Khadiri B. Kharraja N. Kintz A. Nourreddine D. Prévost C. Rigollet H. Savajols P.J. Twin J.P. Vivien K. Zuber 《The European Physical Journal A - Hadrons and Nuclei》1998,2(2):123-127
839.
Ngoc-Minh Lê 《Discrete and Computational Geometry》1996,16(2):177-196
We prove upper bounds on the number ofL
p-spheres passing throughD+1 points in general position in ℝ”, and on the sum of the Betti numbers of the intersection of bisectors in theL
p-metric, wherep is an even positive integer. The bounds found do not depend onp. Our result implies that the complexity of Voronoi diagrams (for point sites in general position) in theL
p-metric is bounded for increasingp. The proof for this upper bound involves the techniques of Milnor [12] and Thom [16] for finding a bound on the sum of the
Betti numbers of algebraic varieties, but instead of the usual degree of polynomials we use their additive complexity, and
apply results of Benedetti and Risler [2], [13]. Furthermore, we prove that inD dimensions and for evenp the number ofL
p-spheres passing throughD+1 points in general position is odd. In particular, combined with results of [8], [9], our results clarify the structure
of Voronoi diagrams based on theL
p-metric (with evenp) in three dimensions. For the proof we use the theory of degree of continuous mappings in ℝD, which is a tool widely applied in nonlinear analysis [14].
This work was partially supported by Deutsche Forschungsgemeinschaft, Grant K1 655/2-1. A preliminary version of this paper
was presented at the 11th Annual Symposium on Theoretical Aspects of Computer Science, France, 1994. 相似文献
840.
A Simplex Approach for Finding Local Solutions of a Linear Bilevel Program by Equilibrium Points 总被引:2,自引:0,他引:2
In this paper, a linear bilevel programming problem (LBP) is considered. Local optimality conditions are derived. They are
based on the notion of equilibrium point of an exact penalization for LBP. It is described how an equilibrium point can be
obtained with the simplex method. It is shown that the information in the simplex tableaux can be used to get necessary and
sufficient local optimality conditions for LBP. Based on these conditions, a simplex type algorithm is proposed, which attains
a local solution of LBP by moving in equilibrium points. A numerical example illustrates how the algorithm works. Some computational
results are reported. 相似文献