The local density of states (LDOS) is a distribution that characterizes the effects of perturbations on quantum systems. Recently, a semiclassical theory was proposed for the LDOS of chaotic billiards and maps. This theory ...

We show that it is possible to extract useful information from the straightforward perturbation theory in classical mechanics. Although the secular terms make the perturbation series useless for large times, these expansions ...

A general result on the structure and dimension of the root subspaces of a linear operator under finite rank perturbations is proved: The increase of dimension from the n-th power of the kernel of the perturbed operator ...

In this note we show that the standard convolution regularization of the Haar system generates Riesz bases of smooth functions for L2(R), providing in this way an alternative to the approach given by Govil and Zalik [Proc. ...

We consider perturbation of frames and frame sequences in a Hilbert space. It is known that small perturbations of a frame give rise to another frame. We show that the canonical dual of the perturbed sequence is a perturbation ...

Using a generalization of the moment problem and the extremal properties of spectral measures corresponding to the self-adjoint extensions of a regular symmetric operator, we study point mass perturbations of spectral ...

We analyse a recent application of homotopy perturbation method to some models for population balances. We show that the only result of the application of this implementation of the perturbation approach is the Taylor ...

We elaborate on the deviation of the Jordan structures of two linear relations that are finite-dimensional perturbations of each other. We compare their number of Jordan chains of length at least n. In the operator case, ...

Loss of species richness and reduced abundance have been the main responses to perturbations of small- and medium-sized mammals in arid and semi-arid areas. Nonetheless, some mammal species whose habitat requirements are ...