INVARIANT MEASURES AND UNIFORM POSITIVE ENTROPY PROPERTY FOR INVERSE LIMITS

In this paper, the interconnection of som e ergodic properties betw een a continuous selfm ap and its inverse lim itis studied. Ithas been proved that(1) theirinvariantBorelproba- bility m easures are identicalup to hom eom orphism and (2) they preserve uniform positive en- tropy property sim ultaneously. As applications, it is also proved that the upper sem i-continu- ous properties of their entropy m aps are restricted each other, and the entropy m ap of the asym ptotically h-expansivecontinuous m ap isuppersem i-continuous, atthe sam e tim e acontin- uous m ap having u.p.e. is topologicalweak-m ixing.

Coexistence of positive and negative magnetic entropy changes in CeMn_2(Si_(1-x)Ge_x)_2 compounds

A series of CeMn2（Si1-xGex）2（x = 0.2, 0.4, 0.6, 0.8） compounds are prepared by the arc-melting method. All the samples primarily crystallize in the Th Cr2Si2-type structure. The temperature dependences of zero-field-cooled（ZFC） and FC magnetization measurements show a transition from antiferromagnetic（AFM） state to ferromagnetic（FM） state at room temperature with the increase of the Ge concentration. For x = 0.4, the sample exhibits two kinds of phase transitions with increasing temperature： from AFM to FM and from FM to paramagnetic（PM） at around TN-197 K and T C-300 K,respectively. The corresponding Arrott curves indicate that the AFM–FM transition is of first-order character and the FM–PM transition is of second-order character. Meanwhile, the coexistence of positive and negative magnetic entropy changes can be observed, which are corresponding to the AFM–FM and FM–PM transitions, respectively.

Shannon information entropies for rectangular multiple quantum well systems with constant total lengths

We first study the Shannon information entropies of constant total length multiple quantum well systems and then explore the effects of the number of wells and confining potential depth on position and momentum information entropy density as well as the corresponding Shannon entropy.We find that for small full width at half maximum（FWHM） of the position entropy density,the FWHM of the momentum entropy density is large and vice versa.By increasing the confined potential depth,the FWHM of the position entropy density decreases while the FWHM of the momentum entropy density increases.By increasing the potential depth,the frequency of the position entropy density oscillation within the quantum barrier decreases while that of the position entropy density oscillation within the quantum well increases.By increasing the number of wells,the frequency of the position entropy density oscillation decreases inside the barriers while it increases inside the quantum well.As an example,we might localize the ground state as well as the position entropy densities of the1 st,2 nd,and 6 th excited states for a four-well quantum system.Also,we verify the Bialynicki–Birula–Mycieslki（BBM）inequality.

The topological entropy for autonomous Lagrangian systems on compact manifolds whose fundamental groups have exponential growth

In this article,we consider the topological entropy for autonomous positive definite Lagrangian systems on connected closed Riemannian manifolds whose fundamental groups have exponential growth.We prove that on each energy level E(x,v)=k with k>c(L),where c(L)is Mane’s critical value,the EulerLagrange flow has positive topological entropy.This extends the classical Dinaburg theorem from geodesic flows to general autonomous positive definite Lagrangian systems.

Pointwise Pseudo-Orbit Tracing Property and Chaos

In this article, we discuss the relationship between pointwise pseudo-orbit tracing property and chaotic properties such as topological mixing. When f has pointwise pseudo-orbit tracing property, we give some equal conditions of uniform positive entropy and completely positive entropy.