Trajectory Synthesis for Fisher Information Maximization

Estimation of model parameters in a dynamic system can be significantly improved with the choice of experimental trajectory. For general, nonlinear dynamic systems, finding globally "best" trajectories is typically not feasible; however, given an initial estimate of the model parameters and an initial trajectory, we present a continuous-time optimization method that produces a locally optimal trajectory for parameter estimation in the presence of measurement noise. The optimization algorithm is formulated to find system trajectories that improve a norm on the Fisher information matrix. A double-pendulum cart apparatus is used to numerically and experimentally validate this technique. In simulation, the optimized trajectory increases the minimum eigenvalue of the Fisher information matrix by three orders of magnitude compared to the initial trajectory. Experimental results show that this optimized trajectory translates to an order of magnitude improvement in the parameter estimate error in practice.Comment: 12 page

A Calibrated Time Domain Envelope Measurement System for the Behavioral Modeling of Power Amplifiers

This paper presents a set-up which enables the generation and the calibrated time domain measurements of complex envelopes of modulated signals at both ports of non linear microwave power amplifiers. The architecture of the characterization tool is given. Examples of error corrected time domain envelopes at the input / output RF ports of a 36 dBm output power – 30dB power gain L-band SSPA are shown. Futhermore, the use of this characterization tool and a suitable processing of measurement data are applied to a novel measurement based behavioral modeling approach of non linear devices accounting for memory effects

Isotope geochemistry and petrogenesis of peralkaline Middle Miocene ignimbrites from central Sonora: relationship with continental break-up and the birth of the Gulf of California

Middle Miocene peralkaline ignimbrites constitute a specific geodynamic marker of the early stage of opening of the Gulf of California, preserved either in central Sonora or the Puertecitos area, in Baja California. Very uniform ages (12-12.5 Ma) obtained on these rocks show that this volcanic episode corresponds to a specific stage in the tectonic evolution of the proto-gulf area. Field observations and slightly different Sr and Nd isotopic signatures support eruptions from several small volume magma batches rather than from a large-volume caldera forming event. Isotopic ratios help to constrain the petrogenesis of the peralkaline liquids by fractional crystallization of transitional basalts in a shallow reservoir, with slight contamination by Precambrian upper crustal material. Less differentiated glomeroporphyritic icelandites erupted at about 11 Ma, mark an increase in the magma production rate and highlight an easier access to the surface, illustrating an advanced stage in the weakening of the continental crust. The tilting of the Middle Tertiary sequences results from a major change in the tectonic regime, from E-W extension giving rise to N-S grabens, to NNW-SSE strike-slip motion that can be related to the transfer of Baja California from North America to the Pacific plate. The location of peralkaline volcanism coincides with the southern edge of the Precambrian crust and the southernmost extension of the California slab window at 12.5 Ma

Evolution of mal ABC transporter operons in the Thermococcales and Thermotogales

<p>Abstract</p> <p>Background</p> <p>The <it>mal </it>genes that encode maltose transporters have undergone extensive lateral transfer among ancestors of the archaea <it>Thermococcus litoralis </it>and <it>Pyrococcus furiosus</it>. Bacterial hyperthermophiles of the order <it>Thermotogales </it>live among these archaea and so may have shared in these transfers. The genome sequence of <it>Thermotoga maritima </it>bears evidence of extensive acquisition of archaeal genes, so its ancestors clearly had the capacity to do so. We examined deep phylogenetic relationships among the <it>mal </it>genes of these hyperthermophiles and their close relatives to look for evidence of shared ancestry.</p> <p>Results</p> <p>We demonstrate that the two maltose ATP binding cassette (ABC) transporter operons now found in <it>Tc. litoralis </it>and <it>P. furiosus </it>(termed <it>mal </it>and <it>mdx </it>genes, respectively) are not closely related to one another. The <it>Tc. litoralis </it>and <it>P. furiosus mal </it>genes are most closely related to bacterial <it>mal </it>genes while their respective <it>mdx </it>genes are archaeal. The genes of the two <it>mal </it>operons in <it>Tt. maritima </it>are not related to genes in either of these archaeal operons. They are highly similar to one another and belong to a phylogenetic lineage that includes <it>mal </it>genes from the enteric bacteria. A unique domain of the enteric MalF membrane spanning proteins found also in these <it>Thermotogales </it>MalF homologs supports their relatively close relationship with these enteric proteins. Analyses of genome sequence data from other <it>Thermotogales </it>species, <it>Fervidobacterium nodosum</it>, <it>Thermosipho melanesiensis</it>, <it>Thermotoga petrophila</it>, <it>Thermotoga lettingae</it>, and <it>Thermotoga neapolitana</it>, revealed a third apparent <it>mal </it>operon, absent from the published genome sequence of <it>Tt. maritima </it>strain MSB8. This third operon, <it>mal3</it>, is more closely related to the <it>Thermococcales</it>' bacteria-derived <it>mal </it>genes than are <it>mal1 </it>and <it>mal2</it>. <it>F. nodosum</it>, <it>Ts. melanesiensis</it>, and <it>Tt. lettingae </it>have only one of the <it>mal1-mal2 </it>paralogs. The <it>mal2 </it>operon from an unknown species of <it>Thermotoga </it>appears to have been horizontally acquired by a <it>Thermotoga </it>species that had only <it>mal1</it>.</p> <p>Conclusion</p> <p>These data demonstrate that the <it>Tc. litoralis </it>and <it>P. furiosus mdx </it>maltodextrin transporter operons arose in the <it>Archaea </it>while their <it>mal </it>maltose transporter operons arose in a bacterial lineage, but not the same lineage as the two maltose transporter operons found in the published <it>Tt. maritima </it>genome sequence. These <it>Tt. maritima </it>maltose transporters are phylogenetically and structurally similar to those found in enteric bacteria and the <it>mal2 </it>operon was horizontally transferred within the <it>Thermotoga </it>lineage. Other <it>Thermotogales </it>species have a third <it>mal </it>operon that is more closely related to the bacterial <it>Thermococcales mal </it>operons, but the data do not support a recent horizontal sharing of that operon between these groups.</p