Complex dynamics and targeted energy transfer in linear oscillators coupled to multi-degree-of-freedom essentially nonlinear attachments

peer reviewedWe study the dynamics of a system of coupled linear oscillators with a multi-DOF end attachment with essential (nonlinearizable) stiffness nonlinearities. We show numerically that the multi-DOF attachment can passively absorb broadband energy from the linear system in a one-way, irreversible fashion, acting in essence as nonlinear energy sink (NES). Strong passive targeted energy transfer from the linear to the nonlinear subsystem is possible over wide frequency and energy ranges. In an effort to study the dynamics of the coupled system of oscillators, we study numerically and analytically the periodic orbits of the corresponding undamped and unforced hamiltonian system with asymptotics and reduction. We prove the existence of a family of countable infinity of periodic orbits that result from combined parametric and external resonance interactions of the masses of the NES. We numerically demonstrate that the topological structure of the periodic orbits in the frequency-energy plane of the hamiltonian system greatly influences the strength of targeted energy transfer in the damped system and, to a great extent, governs the overall transient damped dynamics. This work may be regarded as a contribution towards proving the efficacy the utilizing essentially nonlinear attachments as passive broadband boundary controllers

SF1 and spleen development: new heterozygous mutation, literature review and consequences for NR5A1- mutated patient's management

International audienceSteroidogenic factor 1 (encoded by SF1/NR5A1) is a transcription factor with multiple target genes involved in the development and function of multiple steroidogenic and non-steroidogenic tissues. NR5A1 mutations lead to several phenotypes, including sex reversal, spermatogenesis failure, premature ovarian failure and adrenocortical insufficiency. The implication of NR5A1 mutations in spleen development anomalies was recently highlighted. We provide new evidence of this involvement, describing a novel heterozygous non-sense NR5A1 mutation in a 46,XY-DSD with polysplenia female proband and her father, who had hypospadias and asplenia