Robust localization methods for passivity enforcement of linear macromodels

In this paper we solve a non-smooth convex formulation for passivity enforcement of linear macromodels using robust localization based algorithms such as the ellipsoid and the cutting plane methods. Differently from existing perturbation based techniques, we solve the formulation based on the direct ℌ∞ norm minimization through perturbation of state-space model parameters. We provide a systematic way of defining an initial set which is guaranteed to contain the global optimum. We also provide a lower bound on the global minimum, that grows tighter at each iteration and hence guarantees δ - optimality of the computed solution. We demonstrate the robustness of our implementation by generating accurate passive models for challenging examples for which existing algorithms either failed or exhibited extremely slow convergenc

Sequence polymorphism from EST data in sugarcane: a fine analysis of 6-phosphogluconate dehydrogenase genes

This paper presents preliminary results demonstrating the use of the sugarcane expressed sequence tag (EST) database (SUCEST) to detect single nucleotide polymorphisms (SNPs) inside 6-phosphogluconate dehydrogenase genes (Pgds). Sixty-four Pgd-related EST sequences were identified and partitioned into two clear-cut sets of 14 and 50 ESTs, probably corresponding to two genes, A and B, respectively. Alignment of A sequences allowed the detection of a single SNP while alignment of B sequences permitted the detection of 39 reliable SNPs, 27 of which in the coding sequence of the gene. Thirty-eight SNPs were binucleotidic and a single one was trinucleotidic. Nine insertions/deletions from one to 72 base pairs long were also detected in the noncoding 3? and 5? sequences. The soundness and the consequences of those preliminary observations on sequence polymorphism in sugarcane are discussed.O presente estudo apresenta resultados preliminares demonstrando a utilização da base de dados de ESTs de cana-de-açúcar para detectar polimorfismo de base única (SNP para Single Nucleotide Polymorphism). Sessenta e quatro ESTs relacionados aos genes da 6-phosphogluconate deshydrogenases (Pgds) foram identificados e divididos em dois conjuntos bem delimitados, de 14 e 50 ESTs, correspondendo a dois genes, A e B. O alinhamento das seqüências do grupo A permitiu a detecção de um único SNP e o alinhamento das seqüências do grupo B permitiu a detecção de 39 SNP, incluindo 27 na região codificante do gene. Trinta e oito SNP foram bi-nucleotídicos e um único tri-nucleotídico. Nove inserções/supressões de um até 72 pares de base foram detectados nas regiões não-codificantes 3? ou 5?. A robustez e as conseqüências dessas observações preliminares são discutidas.16116

High genetic diversity at the extreme range edge: nucleotide variation at nuclear loci in Scots pine (Pinus sylvestris L.) in Scotland

Nucleotide polymorphism at 12 nuclear loci was studied in Scots pine populations across an environmental gradient in Scotland, to evaluate the impacts of demographic history and selection on genetic diversity. At eight loci, diversity patterns were compared between Scottish and continental European populations. At these loci, a similar level of diversity (θsil=~0.01) was found in Scottish vs mainland European populations, contrary to expectations for recent colonization, however, less rapid decay of linkage disequilibrium was observed in the former (ρ=0.0086±0.0009, ρ=0.0245±0.0022, respectively). Scottish populations also showed a deficit of rare nucleotide variants (multi-locus Tajima's D=0.316 vs D=−0.379) and differed significantly from mainland populations in allelic frequency and/or haplotype structure at several loci. Within Scotland, western populations showed slightly reduced nucleotide diversity (πtot=0.0068) compared with those from the south and east (0.0079 and 0.0083, respectively) and about three times higher recombination to diversity ratio (ρ/θ=0.71 vs 0.15 and 0.18, respectively). By comparison with results from coalescent simulations, the observed allelic frequency spectrum in the western populations was compatible with a relatively recent bottleneck (0.00175 × 4Ne generations) that reduced the population to about 2% of the present size. However, heterogeneity in the allelic frequency distribution among geographical regions in Scotland suggests that subsequent admixture of populations with different demographic histories may also have played a role

An optimal control approach to determine resistance-type boundary conditions from in-vivo data for cardiovascular simulations

The choice of appropriate boundary conditions is a fundamental step in computational fluid dynamics (CFD) simulations of the cardiovascular system. Boundary conditions, in fact, highly affect the computed pressure and flow rates, and consequently haemodynamic indicators such as wall shear stress (WSS), which are of clinical interest. Devising automated procedures for the selection of boundary conditions is vital to achieve repeatable simulations. However, the most common techniques do not automatically assimilate patient-specific data, relying instead on expensive and time-consuming manual tuning procedures. In this work, we propose a technique for the automated estimation of outlet boundary conditions based on optimal control. The values of resistive boundary conditions are set as control variables and optimized to match available patient-specific data. Experimental results on four aortic arches demonstrate that the proposed framework can assimilate 4D-Flow MRI data more accurately than two other common techniques based on Murray's law and Ohm's law

Complex Power Distribution Network Investigation using SPICE Based Extraction from First Principle Formulations

The modeling and the analysis of the power distribution networks (PDN) within multi-layer printed circuit board is crucial for the investigation of the performance of PCB systems. Carrying out such analyses in SPICE based tools has the advantage of being faster than the corresponding full-wave modeling and it allows obtaining both frequency and time domain results