Adaptive optics imaging of P Cygni in Halpha

We obtained Halpha diffraction limited data of the LBV star P Cyg using the ONERA Adaptive Optics (AO) facility BOA at the OHP 1.52m telescope on October 1997. Taking P Cyg and the reference star 59 Cyg AO long exposures we find that P Cyg clearly exhibits a large and diffuse intensity distribution compared to the 59 Cyg's point-like source. A deconvolution of P Cyg using 59 Cyg as the Point Spread Function was performed by means of the Richardson-Lucy algorithm. P Cyg clearly appears as an unresolved star surrounded by a clumped envelope. The reconstructed image of P Cyg is compared to similar spatial resolution maps obtained from radio aperture synthesis imaging. We put independent constraints on the physics of P Cyg which agree well with radio results. We discuss future possibilities to constrain the wind structure of P Cyg by using multi-resolution imaging, coronagraphy and long baseline interferometry to trace back its evolutionary status.Comment: 10 pages, 19 Encapsulated Postscript figure

Design of the strut braced wing aircraft in the agile collaborative MDO framework

The paper describes the deployment of the AGILE Development Framework to investigate the Strut Braced Wing aircraft configuration. The design process consists of a multilevel multidisciplinary architecture, progressing from the initial conceptual synthesis to the physics based analysis. All the main disciplinary domains, including on board system design and cost assessment, are accounted for in the assembled workflow. Due to the specific characteristics of the Strut Braced Wing configuration, the aeroelastic analysis is the main focus of the study and it is addressed at both high and low fidelity levels. The integration of the engine-wing system is also included in the design process. All the design competences, which are hosted at the different partners, communicate via CPACS (Common Parametric Aircraft Configuration Schema) data schema. All the results generated, including the multidisciplinary design process itself, will be published and made available as part of the AGILE Overall Aircraft Design database

Benthic oxygen exchange over a heterogeneous Zostera noltei meadow in a temperate coastal ecosystem

Seagrass meadows support intense but highly variable benthic metabolic rates that still need to be better evaluated to determine an accurate trophic status. The present study assessed how seagrasses and associated benthic macrofauna control spatiotemporal changes in benthic oxygen exchanges within a temperate bay. Based on seasonal sampling over a complete year cycle, the diffusive oxygen uptake (DOU), community respiration (CR) and gross primary production (GPP) were measured in a Zostera noltei meadow within Arcachon Bay, taking into account its spatial heterogeneity. Oxygen fluxes were assessed in sediment cores, within which benthic macrofauna and seagrass abundances and biomasses were quantified. The presence of Z. noltei did not significantly affect the DOU. Seasonal changes in CR and GPP correlated strongly with temperature in the presence of Z. noltei. The characteristics of benthic macrofauna associated with Z. noltei only weakly affected seasonal changes in CR. High spatial changes in both GPP and CR were mainly driven by the aboveground biomass of Z. noltei. When extrapolated to the whole intertidal area of the bay, in spite of limitations, our results suggest (1) overall higher contributions to CR and GPP from the seagrass meadow than from bare sediments, even though alternative primary producers in bare sediments (likely microphytobenthos) contributed significantly during winter; (2) an annual decrease in CR and GPP of 35 and 41%, respectively, resulting from the decline in Z. noltei of 25% between 2005 and 2007; and (3) a strong seasonality in the magnitude of this decrease, which was high during autumn and low during winter.

Super-resolution in map-making based on a physical instrument model and regularized inversion. Application to SPIRE/Herschel

We investigate super-resolution methods for image reconstruction from data provided by a family of scanning instruments like the Herschel observatory. To do this, we constructed a model of the instrument that faithfully reflects the physical reality, accurately taking the acquisition process into account to explain the data in a reliable manner. The inversion, ie the image reconstruction process, is based on a linear approach resulting from a quadratic regularized criterion and numerical optimization tools. The application concerns the reconstruction of maps for the SPIRE instrument of the Herschel observatory. The numerical evaluation uses simulated and real data to compare the standard tool (coaddition) and the proposed method. The inversion approach is capable to restore spatial frequencies over a bandwidth four times that possible with coaddition and thus to correctly show details invisible on standard maps. The approach is also applied to real data with significant improvement in spatial resolution.Comment: Astronomy & Astrophysic

Multidisciplinary Design and Optimization of Regional Jet Retrofitting Activity

A retrofit analysis on a 90 passengers regional jet aircraft is performed through a multidisciplinary collaborative aircraft design and optimization highlighting the impact on costs and performance. Two different activities are accounted for selecting the best aircraft retrofit solution: a re-engining operation that allows to substitute a conventional power-plant platform with advanced geared turbofan and an on-board-systems architecture modernization, considering different levels of electrification. Besides the variables that are directly dependent from these activities, also scenario variables are considered during the optimization such as the fuel price, the fleet size and the years of utilization of the upgraded systems. The optimization is led by impacts of the retrofitting process on emissions, capital costs and saving costs, computed at industrial level. Overall aircraft design competences (aerodynamics, masses, performance, noise, and emissions) have been computed increasing the level of fidelity and reliability. The whole process is implemented in the framework of the AGILE 4.0 research project in a collaborative remote multidisciplinary approach. Results show that the engine retrofitting can be a profitable solution for both manufacturers and airliners. Conversely, the on-board-system electrification seems to be not convenient in a retrofitting process due to the high capital costs. Depending on the operative scenario, involved stakeholders can properly orient their decision on a retrofitting strategy

Tensor field interpolation with PDEs

We present a unified framework for interpolation and regularisation of scalar- and tensor-valued images. This framework is based on elliptic partial differential equations (PDEs) and allows rotationally invariant models. Since it does not require a regular grid, it can also be used for tensor-valued scattered data interpolation and for tensor field inpainting. By choosing suitable differential operators, interpolation methods using radial basis functions are covered. Our experiments show that a novel interpolation technique based on anisotropic diffusion with a diffusion tensor should be favoured: It outperforms interpolants with radial basis functions, it allows discontinuity-preserving interpolation with no additional oscillations, and it respects positive semidefiniteness of the input tensor data

Bridging topological and functional information in protein interaction networks by short loops profiling

Protein-protein interaction networks (PPINs) have been employed to identify potential novel interconnections between proteins as well as crucial cellular functions. In this study we identify fundamental principles of PPIN topologies by analysing network motifs of short loops, which are small cyclic interactions of between 3 and 6 proteins. We compared 30 PPINs with corresponding randomised null models and examined the occurrence of common biological functions in loops extracted from a cross-validated high-confidence dataset of 622 human protein complexes. We demonstrate that loops are an intrinsic feature of PPINs and that specific cell functions are predominantly performed by loops of different lengths. Topologically, we find that loops are strongly related to the accuracy of PPINs and define a core of interactions with high resilience. The identification of this core and the analysis of loop composition are promising tools to assess PPIN quality and to uncover possible biases from experimental detection methods. More than 96% of loops share at least one biological function, with enrichment of cellular functions related to mRNA metabolic processing and the cell cycle. Our analyses suggest that these motifs can be used in the design of targeted experiments for functional phenotype detection.This research was supported by the Biotechnology and Biological Sciences Research Council (BB/H018409/1 to AP, ACCC and FF, and BB/J016284/1 to NSBT) and by the Leukaemia & Lymphoma Research (to NSBT and FF). SSC is funded by a Leukaemia & Lymphoma Research Gordon Piller PhD Studentship

A combined first and second order variational approach for image reconstruction

In this paper we study a variational problem in the space of functions of bounded Hessian. Our model constitutes a straightforward higher-order extension of the well known ROF functional (total variation minimisation) to which we add a non-smooth second order regulariser. It combines convex functions of the total variation and the total variation of the first derivatives. In what follows, we prove existence and uniqueness of minimisers of the combined model and present the numerical solution of the corresponding discretised problem by employing the split Bregman method. The paper is furnished with applications of our model to image denoising, deblurring as well as image inpainting. The obtained numerical results are compared with results obtained from total generalised variation (TGV), infimal convolution and Euler's elastica, three other state of the art higher-order models. The numerical discussion confirms that the proposed higher-order model competes with models of its kind in avoiding the creation of undesirable artifacts and blocky-like structures in the reconstructed images -- a known disadvantage of the ROF model -- while being simple and efficiently numerically solvable.Comment: 34 pages, 89 figure