Invariants and coinvariants of semilocal units modulo elliptic units

Let p be a prime number, and let k be an imaginary quadratic field in which p decomposes into two primes \mathfrak{p} and \bar{\mathfrak{p}}. Let k_\infty be the unique Z_p-extension of k which is unramified outside of \mathfrak{p}, and let K_\infty be a finite extension of k_\infty, abelian over k. Let U_\infty/C_\infty be the projective limit of principal semi-local units modulo elliptic units. We prove that the various modules of invariants and coinvariants of U_\infty/C_\infty are finite.Comment: 13 page

Nonlinear Generalization of Den Hartog's Equal-Peak Method

This study addresses the mitigation of a nonlinear resonance of a mechanical system. In view of the narrow bandwidth of the classical linear tuned vibration absorber, a nonlinear absorber, termed the nonlinear tuned vibration absorber (NLTVA), is introduced in this paper. An unconventional aspect of the NLTVA is that the mathematical form of its restoring force is tailored according to the nonlinear restoring force of the primary system. The NLTVA parameters are then determined using a nonlinear generalization of Den Hartog's equal-peak method. The mitigation of the resonant vibrations of a Duffing oscillator is considered to illustrate the proposed developments

Design Procedure of a Nonlinear Vibration Absorber Using Bifurcation Analysis

A nonlinear energy sink (NES) is characterized by its ability to passively realize targeted energy transfer as well as multimodal damping. This latter feature seems to make this device very well suited for reducing the vibration level of MDOF linear structures. The perspective of dealing with MDOF linear primary structures requires the development of an efficient NES design procedure. This paper poses the basis of such a procedure based upon the bifurcation analysis of a system composed of a linear oscillator coupled to a NES, using the software MatCont

The Gras conjecture in function fields by Euler systems

We use Euler systems to prove the Gras conjecture for groups generated by Stark units in global function fields. The techniques applied here are classical and go back to Thaine, Kolyvagin and Rubin. We obtain our Euler systems from the torsion points of sign-normalized Drinfel'd modules.Comment: accepted for publication in the Bulletin of the London Mathematical Societ

Developing new tools to address the impact of climate change on the evolutionary and distributional history in plant lineages

Tesis doctoral inédita leída en la Universidad Autónoma de Madrid, Facultad de Ciencias, Departamento de Biología. Fecha de lectura: 28-02-202

On Gras conjecture for imaginary quadratic fields

In this paper we extend methods of Rubin to prove the Gras conjecture for abelian extensions of a given imaginary quadratic field k and prime numbers p which divide the number of roots of unity in k.Comment: accepted for publication in Canadian Mathematical Bulleti