VUV photo-processing of PAH cations: quantitative study on the ionization versus fragmentation processes

Interstellar polycyclic aromatic hydrocarbons (PAHs) are strongly affected by the absorption of vacuum ultraviolet (VUV) photons in the interstellar medium (ISM), yet the branching ratio between ionization and fragmentation is poorly studied. This is crucial for the stability and charge state of PAHs in the ISM in different environments, affecting in turn the chemistry, the energy balance, and the contribution of PAHs to the extinction and emission curves. We studied the interaction of PAH cations with VUV photons in the 7-20 eV range from the synchrotron SOLEIL beamline, DESIRS. We recorded by action spectroscopy the relative intensities of photo-fragmentation and photo-ionization for a set of eight PAH cations ranging in size from 14 to 24 carbon atoms, with different structures. At photon energies below ~13.6 eV fragmentation dominates for the smaller species, while for larger species ionization is immediately competitive after the second ionization potential (IP). At higher photon energies, all species behave similarly, the ionization yield gradually increases, leveling off between 0.8 and 0.9 at ~18 eV. Among isomers, PAH structure appears to mainly affect the fragmentation cross section, but not the ionization cross section. We also measured the second IP for all species and the third IP for two of them, all are in good agreement with theoretical ones confirming that PAH cations can be further ionized in the diffuse ISM. Determining actual PAH dication abundances in the ISM will require detailed modeling. Our measured photo-ionization yields for several PAH cations provide a necessary ingredient for such models

Estimation de sources de chaleur dans les matériaux minces

Dans ce travail, une méthode d'estimation de source est mise au point et elle est associée à une méthode de filtrage des données par décomposition en valeurs singulières. Cette méthode testée dans un premier temps sur des données numériques, est ensuite appliquée à des mesures de températures par thermographie infrarouge obtenues lors d'une expérience dédiée où la position et l'intensité des sources sont connues. L'objectif final de cette étude (non détaillée dans ce papier) sera d'utiliser cette méthode sur des mesures de températures obtenues lors de tests de traction sur des polymères

Achieving rotorcraft noise and emissions reduction for 'Clean Sky' - The measurement of success

This paper describes the work done and strong interaction between Cranfield University as member of the Technology Evaluator (TE) team , Green Rotorcraft (GRC) Integrated Technology Demonstrator (ITD) and Sustainable and Green Engine (SAGE) ITD of the Clean Sky Joint Technology Initiative (JTI). The aim of Clean Sky is to develop and integrate new and innovative technologies that will hel p meeting the emission and noise reduction targets set by the Advisory Council for Aviation Research and Innovation in Europe (ACARE) for aircraft of next generation. The GRC and SAGE ITDs are responsible for developing new helicopter airframe and engine t echnologies respectively, whilst the TE has the distinctive role of assessing the environmental impact of these technologies at single flight (mission), airport and Air Transport System levels (ATS). Cranfield University as a member of the TE is responsibl e for the mission trajectory definition and for conducting the environmental performance assessments . The assessments reported herein have been performed by using a GRC - developed multi - disciplinary simulation framework called PhoeniX (Platform Hosting Oper ational and Environmental Investigations for Rotorcraft) that comprises various computational modules. These modules include a rotorcraft performance code (EUROPA), an engine performance and emissions simulation tool (GSP) and a noise prediction code (HELE NA). PhoeniX can predict the performance of a helicopter along a prescribed 4D trajectory offering a complete helicopter mission analysis. In the context of the TE assessments reported herein, three helicopter classes are examined, namely a Twin Engine Lig ht (TEL) configuration, for Emergency Medical Service (EMS) and Police missions, and a Single Engine Light (SEL) configuration for Passenger/Transport missions, and a Twin Engine Heavy (TEH) configuration for Oil & Gas missions. The different technologies assessed reflect three simulation points which are the ‘Baseline’ Year 2000 technology, ‘Reference’ Y2020 technology, without Clean Sky benefits, and finally the ‘Conceptual’, reflecting Y2020 technology with Clean Sky benefits. The results of this study i llustrate the potential that incorporated technologies possess in terms of improving performance and gas emission metrics such as fuel burn, CO2, NOx as well as the noise footprint on the ground

Electrodynamics with Lorentz-violating operators of arbitrary dimension

The behavior of photons in the presence of Lorentz and CPT violation is studied. Allowing for operators of arbitrary mass dimension, we classify all gauge-invariant Lorentz- and CPT-violating terms in the quadratic Lagrange density associated with the effective photon propagator. The covariant dispersion relation is obtained, and conditions for birefringence are discussed. We provide a complete characterization of the coefficients for Lorentz violation for all mass dimensions via a decomposition using spin-weighted spherical harmonics. The resulting nine independent sets of spherical coefficients control birefringence, dispersion, and anisotropy. We discuss the restriction of the general theory to various special models, including among others the minimal Standard-Model Extension, the isotropic limit, the case of vacuum propagation, the nonbirefringent limit, and the vacuum-orthogonal model. The transformation of the spherical coefficients for Lorentz violation between the laboratory frame and the standard Sun-centered frame is provided. We apply the results to various astrophysical observations and laboratory experiments. Astrophysical searches of relevance include studies of birefringence and of dispersion. We use polarimetric and dispersive data from gamma-ray bursts to set constraints on coefficients for Lorentz violation involving operators of dimensions four through nine, and we describe the mixing of polarizations induced by Lorentz and CPT violation in the cosmic-microwave background. Laboratory searches of interest include cavity experiments. We present the theory for searches with cavities, derive the experiment-dependent factors for coefficients in the vacuum-orthogonal model, and predict the corresponding frequency shift for a circular-cylindrical cavity.Comment: 58 pages two-column REVTeX, accepted in Physical Review

Distributed path planning for controlling a fleet of UAVs : application to a team of quadrotors

International audienc

Grammatikee têes glóossees helleenikees en teê dialecttoo iberikeê = Grammatica de la lengua griega en idioma español

Precede al tít. transliterado, el mismo en caracteres griegos.Texto en latín y griego.Sign.: ã-e8, A-Z8, 2A-2M8.Copia digital : Junta de Castilla y León. Consejería de Cultura y Turismo, 201

Publisher Correction: Carbon dioxide sink in the Arctic Ocean from cross-shelf transport of dense Barents Sea water

In the version of this article initially published, author Cora Hörstmann was wrongly listed with a second affiliation with the Department of Ecoscience–Applied Marine Ecology and Modelling, Aarhus University rather than the Mediterranean Institute of Oceanography (MIO), Marseille, France. Furthermore, references 83–97, now found in the Supplementary Tables caption, were wrongly cited in the Data Availability section. The errors have been corrected in the HTML and PDF versions of the article

Data-Driven Constitutive Model for the Inelastic Response of Metals:Application to 316H Steel

Predictions of the mechanical response of structural elements are conditioned by the accuracy of constitutive models used at the engineering length-scale. In this regard, a prospect of mechanistic crystal-plasticity-based constitutive models is that they could be used for extrapolation beyond regimes in which they are calibrated. However, their use for assessing the performance of a component is computationally onerous. To address this limitation, a new approach is proposed whereby a surrogate constitutive model (SM) of the inelastic response of 316H steel is derived from a mechanistic crystal plasticity-based polycrystal model tracking the evolution of dislocation densities on all slip systems. The latter is used to generate a database of the expected plastic response and dislocation content evolution associated with several instances of creep loading. From the database, a SM is developed. It relies on the use of orthogonal polynomial regression to describe the evolution of the dislocation content. The SM is then validated against predictions of the dead load creep response given by the polycrystal model across a range of temperatures and stresses. When the SM is used to predict the response of 316H during complex non monotonic loading, extrapolating to new loading conditions, it is found that predictions compare particularly well against those from the physics-based polycrystal model

Complex interaction between dengue virus replication and expression of miRNA-133a

Background: Dengue virus (DENV) is the most common vector-borne viral infection worldwide with approximately 390 million cases and 25,000 reported deaths each year. MicroRNAs (miRNAs) are small non-coding RNA molecules responsible for the regulation of gene expression by repressing mRNA translation or inducing mRNA degradation. Although miRNAs possess antiviral activity against many mammalian-infecting viruses, their involvement in DENV replication is poorly understood. Methods: Here, we explored the relationship between DENV and cellular microRNAs using bioinformatics tools. We overexpressed miRNA-133a in Vero cells to test its role in DENV replication and analyzed its expression using RT-qPCR. Furthermore, the expression of polypyrimidine tract binding protein (PTB), a protein involved in DENV replication, was analyzed by western blot. In addition, we profiled miRNA-133a expression in Vero cells challenged with DENV-2, using Taqman miRNA. Results: Bioinformatic analysis revealed that the 3' untranslated region (3'UTR) of the DENV genome of all four DENV serotypes is targeted by several cellular miRNAs, including miRNA-133a. We found that overexpression of synthetic miRNA-133a suppressed DENV replication. Additionally, we observed that PTB transcription, a miRNA-133a target, is down-regulated during DENV infection. Based in our results we propose that 3' UTR of DENV downregulates endogenous expression of miRNA-133a in Vero cells during the first hours of infection. Conclusions: miRNA-133a regulates DENV replication possibly through the modulation of a host factor such as PTB. Further investigations are needed to verify whether miRNA-133a has an anti-DENV effect in vivo