Stochastically perturbed flows: Delayed and interrupted evolution

We present analytical expressions for the time-dependent and stationary probability distributions corresponding to a stochastically perturbed one-dimensional flow with critical points, in two physically relevant situations: delayed evolution, in which the flow alternates with a quiescent state in which the variate remains frozen at its current value for random intervals of time; and interrupted evolution, in which the variate is also re-set in the quiescent state to a random value drawn from a fixed distribution. In the former case, the effect of the delay upon the first passage time statistics is analyzed. In the latter case, the conditions under which an extended stationary distribution can exist as a consequence of the competition between an attractor in the flow and the random re-setting are examined. We elucidate the role of the normalization condition in eliminating the singularities arising from the unstable critical points of the flow, and present a number of representative examples. A simple formula is obtained for the stationary distribution and interpreted physically. A similar interpretation is also given for the known formula for the stationary distribution in a full-fledged dichotomous flow.Comment: 27 pages; no figures. Submitted to Stochastics and Dynamic

Progressive damage in stitched composites: Static tensile tests and tension-tension fatigue

The paper describes progressive damage in static tensile tests and tension-tension fatigue in structurally stitched carbon/epoxy NCF composites, in comparison with their non-stitched counterparts. Analogies between damage development in quasi-static tension and tension-tension fatigue are analyzed and links between the damage initiation thresholds in quasi-static tests and fatigue life are established

Orbital ordering in manganites in the band approach

We consider the orbital ordering in LaMnO3 and similar systems, proceeding from the band picture. We show that for the realistic magnetic structure of A-type there exists a complete nesting betweeen two e_g-bands. As a result there occurs an instability towards an excitonic insulator-like state -- an electron-hole pairing with the wave vector Q=(\pi,\pi), which opens a gap in the spectrum and makes the system insulating. In the resulting state there appeasr an orbital ordering -- orbital density wave (ODW), the type of which coincides with those existing in LaMnO3.Comment: 4 pages, 2 figure

Remarks on a normal subgroup of GA_n

We show that the subgroup generated by locally finite polynomial automorphisms of k^n is normal in GA_n. Also, some properties of normal subgroups of GA_n containing all diagonal automorphisms are given.Comment: 5 page

Crop ontology in support of conservation and use of banana genetic resources

Poster presented at Workshop on Crop Ontology and Phenotyping Data Interoperability. Montpellier (France), 31 Mar-4 Apr 201

Quantum limited sensitivity of SET-based displacement detectors

We consider a model of a quantum-mechanical resonator capacitively coupled to a single electron transistor (SET). The tunnel current in the SET is modulated by the vibrations of the resonator, and thus the system operates as a displacement detector. We analyze the effect of the back-action noise of charge fluctuations in the SET onto the dynamics of the resonator and evaluate the displacement sensitivity of the system. The relation between the "classical" and "quantum" parts of the SET charge noise and their effect on the measured system are also discussed.Comment: 4 pages, 2 eps fig