In recent papers, new sets of Sheffer and Brenke polynomials based on higher order Bell numbers have been studied, and several integer sequences related to them have been introduced. In this article other types of Sheffer polynomials are considered, by introducing the adjoint Poisson-Charlier and the adjoint Related polynomials.

Front propagation in two-dimensional steady and unsteady cellular flows is investigated in the limit of very fast reaction and sharp front, i.e., in the geometrical optics limit. For the steady flow, a simplified model allows for an analytical prediction of the front speed v(f) dependence on the stirring intensity U, which is in good agreement with numerical estimates. In particular, at large U, the behavior v(f)similar toU/log(U) is predicted. By adding small scales to the velocity field we found that their main effect is to renormalize the flow intensity.

The study takes up some issues relating to the location of the workshops that produced the valuable figured ambers that marked the aristocratic burials of southern Italy from the eighth to fifth century BC. The contribution of findings and recent studies enabled us to assign some groups of artifacts to the activity of different workshops and even to identify outstanding artistic personalities, highlighting the undeniable stylistic connections between them.

The first carved ambers appear in the Adriatic area at the end of the eighth century BC with the beginning of the Orientalizing period. Among the most active centers, the Etruscan Verucchio is one of the main poles for the sorting of amber. At the beginning of the sixth century, a fundamental role is exercised from Piceno and the Etruscan Felsina, whose intercept part of the tra!cs previously directed on the Adriatic road.

In this paper we revisit the problem of performing a QZ step with a so-called "perfect shift", which is an "exact" eigenvalue of a given regular pencil lambda B-A in unreduced Hessenberg-Triangular form. In exact arithmetic, the QZ step moves that eigenvalue to the bottom of the pencil, while the rest of the pencil is maintained in Hessenberg-Triangular form, which then yields a deflation of the given eigenvalue. But in finite-precision the QZ step gets "blurred" and precludes the deflation of the given eigenvalue.

Casual mutations and natural selection have driven the evolution of protein amino acid sequences that we observe at present in nature. The question about which is the dominant force of proteins evolution is still lacking of an unambiguous answer. Casual mutations tend to randomize protein sequences while, in order to have the correct functionality, one expects that selection mechanisms impose rigid constraints on amino acid sequences.

We present a numerical study of two-dimensional turbulent flows in the enstropy cascade regime, with different large-scale energy sinks. In particular, we study the statistics of more-than-differentiable velocity fluctuations by means of two sets of statistical estimators, namely inverse statistics and second-order differences. In this way, we are able to probe statistical fluctuations that are not captured by the usual spectral analysis. We show that a new set of exponents associated to more-than-differentiable fluctuations of the velocity field exists.

An efficient approach to the calculation of the E-entropy is proposed. The method is based on the idea of looking at the information content of a string nf data hv annalyzing the signal only nt thp instants when the fluctuations are larger than a certain threshold is an element of, i.e., by looking at the exit-time statistics. The practical and theoretical advantages of our method with respect to the usual one are shown by the examples of a deterministic map and a self-affine stochastic process.