1,366 research outputs found
Protection et mise en valeur touristique d'un site géomorphologique: la région du Sanetsch (Valais, Suisse).
Efficient Exploration of Microstructure-Property Spaces via Active Learning
In materials design, supervised learning plays an important role for optimization and inverse modeling of microstructure-property relations. To successfully apply supervised learning models, it is essential to train them on suitable data. Here, suitable means that the data covers the microstructure and property space sufficiently and, especially for optimization and inverse modeling, that the property space is explored broadly. For virtual materials design, typically data is generated by numerical simulations, which implies that data pairs can be sampled on demand at arbitrary locations in microstructure space. However, exploring the space of properties remains challenging. To tackle this problem, interactive learning techniques known as active learning can be applied. The present work is the first that investigates the applicability of the active learning strategy query-by-committee for an efficient property space exploration. Furthermore, an extension to active learning strategies is described, which prevents from exploring regions with properties out of scope (i.e., properties that are physically not meaningful or not reachable by manufacturing processes)
Connections and dynamical trajectories in generalised Newton-Cartan gravity I. An intrinsic view
The "metric" structure of nonrelativistic spacetimes consists of a one-form
(the absolute clock) whose kernel is endowed with a positive-definite metric.
Contrarily to the relativistic case, the metric structure and the torsion do
not determine a unique Galilean (i.e. compatible) connection. This subtlety is
intimately related to the fact that the timelike part of the torsion is
proportional to the exterior derivative of the absolute clock. When the latter
is not closed, torsionfreeness and metric-compatibility are thus mutually
exclusive. We will explore generalisations of Galilean connections along the
two corresponding alternative roads in a series of papers. In the present one,
we focus on compatible connections and investigate the equivalence problem
(i.e. the search for the necessary data allowing to uniquely determine
connections) in the torsionfree and torsional cases. More precisely, we
characterise the affine structure of the spaces of such connections and display
the associated model vector spaces. In contrast with the relativistic case, the
metric structure does not single out a privileged origin for the space of
metric-compatible connections. In our construction, the role of the Levi-Civita
connection is played by a whole class of privileged origins, the so-called
torsional Newton-Cartan (TNC) geometries recently investigated in the
literature. Finally, we discuss a generalisation of Newtonian connections to
the torsional case.Comment: 79 pages, 7 figures; v2: added material on affine structure of
connection space, former Section 4 postponed to 3rd paper of the serie
Recognition of 2D modelized objects by a discrete relaxation method
In this paper, a discrete relaxation method is described . The
aim of this method is the recognition of 2D objects, a model of
which having prealably be established. The model is based on
two kinds of features : straight segments and circles . The
approach is both forward and backward ; so, it is not necessary
to detect all the primitives at the beginning of the procedure
new primitives may be detected, if necessary, during the
relaxation procedure .L'article présente une méthode de relaxation discrÚte pour la
reconnaissance d'objets plans dont on a effectué une modélisation
préalable . Cette modélisation est réalisée à l'aide de
primitives du type segments de droite ou cercles . L'approche
est descendante et ascendante, permettant, par un retour au
niveau de l'image pour détecter de nouvelles primitives,
d'éviter un prétraitement exhaustif de l'image
Dental Shape Variation and Phylogenetic Signal in the Rattini Tribe Species of Mainland Southeast Asia
We would like to thank Pierre-Henri Fabre for providing the phylogeny for this study. The collection of specimens used was funded by the French ANR Biodiversity, grant ANR 07 BDIV 012 CERoPath project (www.ceropath.org), and by the French ANR CP&ES, grant ANR 11 CPEL 002 BiodivHealthSEA project (www.biodivhealthsea.org). We also thank Madoudou Garba and Gauthier Dobigny (CBGP-IRD) for providing additional specimens. We greatly thank all local communities and their leaders for permission and invaluable help during field trapping. Special thanks to the CERoPath and BiodivHealthSEA teams and the drivers for their invaluable help during fieldwork. We would also like to thank Maeve McMahon for help with manuscript editing and preparation.Peer reviewedPublisher PD
Etude expérimentale d'un arc impulsionnel entre des contacts Ag et Ag-C
International audienc
Single-sex schistosome infections of definitive hosts: Implications for epidemiology and disease control in a changing world
Extracellular Bacterial Pathogen Induces Host Cell Surface Reorganization to Resist Shear Stress
Bacterial infections targeting the bloodstream lead to a wide array of devastating diseases such as septic shock and meningitis. To study this crucial type of infection, its specific environment needs to be taken into account, in particular the mechanical forces generated by the blood flow. In a previous study using Neisseria meningitidis as a model, we observed that bacterial microcolonies forming on the endothelial cell surface in the vessel lumen are remarkably resistant to mechanical stress. The present study aims to identify the molecular basis of this resistance. N. meningitidis forms aggregates independently of host cells, yet we demonstrate here that cohesive forces involved in these bacterial aggregates are not sufficient to explain the stability of colonies on cell surfaces. Results imply that host cell attributes enhance microcolony cohesion. Microcolonies on the cell surface induce a cellular response consisting of numerous cellular protrusions similar to filopodia that come in close contact with all the bacteria in the microcolony. Consistent with a role of this cellular response, host cell lipid microdomain disruption simultaneously inhibited this response and rendered microcolonies sensitive to blood flowâgenerated drag forces. We then identified, by a genetic approach, the type IV pili component PilV as a triggering factor of plasma membrane reorganization, and consistently found that microcolonies formed by a pilV mutant are highly sensitive to shear stress. Our study shows that bacteria manipulate host cell functions to reorganize the host cell surface to form filopodia-like structures that enhance the cohesion of the microcolonies and therefore blood vessel colonization under the harsh conditions of the bloodstream
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