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1.
Mário Bessa 《Journal of Differential Equations》2006,228(2):685-706
We prove that for a C0-generic (a dense Gδ) subset of all the 2-dimensional conservative nonautonomous linear differential systems, either Lyapunov exponents are zero or there is a dominated splitting μ almost every point. 相似文献
2.
A fully-automated system has been developed to measure changes in ultrasonic velocity and the attenuation coefficient resulting from changes in temperature and magnetic field. Accuracy and sensitivity comparable to the pulse-echo overlap technique have been achieved together with an increase in temperature resolution and sample throughput as a result of the automation. All components of the instrumentation are commercially available. 相似文献
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4.
sio Bessa Ramos 《Macromolecular theory and simulations》2011,20(5):320-328
In the present work, we revisit the effect of macromolecular crowding on the sizes of flexible neutral polymer chains. Motivated by recent experimental measurements on crowding effects on neutral flexible polymers chains, we perform Monte Carlo simulations on a model system consisting of hard spheres (HS) and a neutral flexible polymer chain. We find that, depending on the ratio of the sizes of the colloidal particles to the sizes of the polymer chain, and thus, on the extent of the colloid partitioning among the chain segments and the solution, the flexible polymeric coil may be either continuously compressed, or initially compressed followed by a reswelling at high enough colloid concentration. The chain behavior is thus nonmonotonic, a point which, apart from the work of Khalatur et al., has not so far been stressed in simulations of flexible polymer chains under crowding conditions. A thermodynamic model for the polymer–colloid interactions based on the Gibbs–Duhem equation and on a “Flory‐type” argument is also presented, emphasizing the indirect influence of macromolecular crowding on the monomers chemical potential. We show explicitly that under crowding conditions, the colloids are driven into the most compact coil states. These analytical results are compared with the results of the potential of mean force between the chain center of mass and the colloids obtained from the Monte Carlo simulations, and a reasonable agreement is found. The implications of the aforementioned results are further discussed in the context of biological systems, specially those for which macromolecular crowding is supposed to play the important role of including preferentially other (charged) macromolecules into the colloid‐compressed polymer phase.
5.
G. Pacelli Bessa Luquesio P. Jorge J. Fabio Montenegro 《Journal of Geometric Analysis》2010,20(1):63-71
We show that the spectrum of a complete submanifold properly immersed into a ball of a Riemannian manifold is discrete, provided
the norm of the mean curvature vector is sufficiently small. In particular, the spectrum of a complete minimal surface properly
immersed into a ball of ℝ3 is discrete. This gives a positive answer to a question of Yau (Asian J. Math. 4:235–278, 2000). 相似文献
6.
Let ACD(M,SL(d,R)) denote the pairs (f,A) so that f ∈ A ⊂ Diff1(M) is a C1-Anosov transitive diffeomorphisms and A is an SL(d,R) cocycle dominated with respect to f. We prove that open and densely in ACD(M,SL(d,R)), in appropriate topologies, the pair (f,A) has simple spectrum with respect to the unique maximal entropy measure μf. Then, we prove prevalence of trivial spectrum near the dynamical cocycle of an area-preserving map and also for generic cocycles in AutLeb(M) × Lp(M,SL(d,R)). 相似文献
7.
Makosch M Kartusch C Sá J Duarte RB van Bokhoven JA Kvashnina K Glatzel P Fernandes DL Nachtegaal M Kleymenov E Szlachetko J Neuhold B Hungerbühler K 《Physical chemistry chemical physics : PCCP》2012,14(7):2164-2170
An autoclave reactor was modified to perform simultaneously high energy resolution fluorescence detected X-ray absorption spectroscopy (HERFD XAS) and attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy measurements without altering the reactor design. This operando cell allows one to follow changes in the electronic and geometric structure of the catalyst with HERFD XAS and relate them to the simultaneously detected activity and reaction species with ATR-FTIR formed during the reaction in the liquid phase. The capability of the cell is demonstrated by two studies. The first shows the reduction of Au/CeO(2) precursors in different solvents. The second shows that mainly Au(0) is present in the hydrogenation of nitrobenzene over Au/CeO(2). 相似文献
8.
We prove that a volume-preserving three-dimensional flow can be C1-approximated by a volume-preserving Anosov flow or else by another volume-preserving flow exhibiting a homoclinic tangency. This proves the conjecture of Palis for conservative 3-flows and with respect to the C1-topology. 相似文献
9.
We present a method to obtain lower bounds for firstDirichlet eigenvalue in terms of vector fields with positivedivergence. Applying this to the gradient of a distance functionwe obtain estimates of eigenvalue of balls inside the cut locus and of domains M B
N
(p, r) in submanifolds M
Nwith locally bounded mean curvature. Forsubmanifolds of Hadamard manifolds with bounded mean curvaturethese lower bounds depend only on the dimension of the submanifold and the bound on its mean curvature. 相似文献
10.
G. Pacelli Bessa Leandro F. Pessoa 《Bulletin of the Brazilian Mathematical Society》2014,45(2):243-265
Based on ideas of L. Alías, D. Impera and M. Rigoli developed in [13], we present a fairly general weak/Omori-Yau maximum principle for trace operators. We apply this version of maximum principle to generalize several higher order mean curvature estimates and to give an extension of Alias-Impera-Rigoli Slice Theorem of [13, Thm. 16 and 21], see Theorems 5 and 6. 相似文献