Modeling the shortening history of a fault tip fold using structural and geomorphic records of deformation

We present a methodology to derive the growth history of a fault tip fold above a basal detachment. Our approach is based on modeling the stratigraphic and geomorphic records of deformation, as well as the finite structure of the fold constrained from seismic profiles. We parameterize the spatial deformation pattern using a simple formulation of the displacement field derived from sandbox experiments. Assuming a stationary spatial pattern of deformation, we simulate the gradual warping and uplift of stratigraphic and geomorphic markers, which provides an estimate of the cumulative amounts of shortening they have recorded. This approach allows modeling of isolated terraces or growth strata. We apply this method to the study of two fault tip folds in the Tien Shan, the Yakeng and Anjihai anticlines, documenting their deformation history over the past 6–7 Myr. We show that the modern shortening rates can be estimated from the width of the fold topography provided that the sedimentation rate is known, yielding respective rates of 2.15 and 1.12 mm/yr across Yakeng and Anjihai, consistent with the deformation recorded by fluvial and alluvial terraces. This study demonstrates that the shortening rates across both folds accelerated significantly since the onset of folding. It also illustrates the usefulness of a simple geometric folding model and highlights the importance of considering local interactions between tectonic deformation, sedimentation, and erosion

Impact of reanalysis boundary conditions on downscaled Atlantic hurricane activity

Climate models are capable of producing features similar to tropical cyclones, but typically display strong biases for many of the storm physical characteristics due to their relatively coarse resolution compared to the size of the storms themselves. One strategy that has been adopted to circumvent this limitation is through the use of a hybrid downscaling technique, wherein a large set of synthetic tracks are created by seeding disturbances in the large-scale environment. Here, we evaluate the ability of this technique at reproducing many of the characteristics of the recent North Atlantic hurricane activity as well as its sensitivity to the choice of the reanalysis dataset used as boundary conditions. In particular, we show that the geographical and intensity distributions are well reproduced, but that the technique has difficulty capturing the large difference in activity observed between the most recent active and quiescent phase. Although the signal is somewhat reduced compared to observation, the technique also detects a significant decrease in the intensification rate of hurricanes near the coastal US during the active phase compared to the quiescent phase. Finally, the influence of the El Niño Southern Oscillation on hurricane activity is generally well captured as well, but the technique fails to reproduce the increase in activity over the western part of the basin during Modoki El Niños.We would like to thank NOAA’s National Centers for Environmental Information for making the IBTrACS data available. JPB and LPC would like to acknowledge the financial support from the Ministerio de Economa y Competitividad (MINECO; Project GL2014-55764-R). LPC’s contract is co-financed by the MINECO under Juan de la Cierva Incorporacin postdoctoral fellowship number IJCI-2015-23367. MB would like to acknowledge financial support from the Natural Sciences and Engineering Research Council (NSERC) of Canada. Finally, we are grateful to Kerry Emanuel for providing the data as well as some useful feedback, and two anonymous reviewers for their helpful comments.Peer ReviewedPostprint (published version

Utilisation de la grille EGI pour l'astrophysique de très hautes énergies avec H.E.S.S.

Utilisation de la grille EGI pour l'astrophysique de très hautes énergies avec H.E.S.S

Lagrangian Point Force regularization for dispersed two-phase flows

International audienceThe present paper presents a regularization procedure of the Lagrangian point-particle approach for the simulation of dispersed two-phase flows in a statistical framework. The aim is to regularize the probability presence of a particle, written as a Dirac delta function centered on the particle position in the standard formulation, by a Gaussian like distribution. The associated regularization length scale is obtained by solving additional transport equations in the Lagrangian framework. The regularization itself is then achieved by solving two non-linear diffusion equations. The first diffusion equations allows to spread the field of spatially varying diffusion coefficients required for regularization over the computational mesh. Once this field is defined, regularization of the Lagrangian fields to be projected on the Eulerian grid such as particle density, particle velocity, etc... is performed. These ideas are then tested on simplified one-dimensional test cases. While preliminary results seem encouraging as the dispersed phase fields projected on the Eulerian grid appear much less sensitive to the initial sampling of the spray, further tests on more realistic test cases are necessary to conclude on precision gains with repect to the additional computational expense resulting from the regularization procedure

Lattice stability and formation energies of intrinsic defects in Mg2Si and Mg2Ge via first principles simulations

We report an ab initio study of the semiconducting Mg2X (with X = Si, Ge) compounds and in particular we analyze the formation energy of the different point defects with the aim to understand the intrinsic doping mechanisms. We find that the formation energy of Mg2Ge is 50 % larger than the one of Mg2Si, in agreement with the experimental tendency. From the study of the stability and the electronic properties of the most stable defects taking into account the growth conditions, we show that the main reason for the n-doping in these materials comes from interstitial magnesium defects. Conversely, since other defects acting like acceptors such as Mg vacancies or multivacancies are more stable in Mg2Ge than in Mg2Si, this explains why Mg2Ge can be of n or p type, contrary to Mg2Si. The finding that the most stable defects are different in Mg2Si and Mg2Ge and depend on the growth conditions is important and must be taken into account in the search of the optimal doping to improve the thermoelectric properties of these materials.Comment: 25 pages, 6 Table

Linear Haskell: practical linearity in a higher-order polymorphic language

Linear type systems have a long and storied history, but not a clear path forward to integrate with existing languages such as OCaml or Haskell. In this paper, we study a linear type system designed with two crucial properties in mind: backwards-compatibility and code reuse across linear and non-linear users of a library. Only then can the benefits of linear types permeate conventional functional programming. Rather than bifurcate types into linear and non-linear counterparts, we instead attach linearity to function arrows. Linear functions can receive inputs from linearly-bound values, but can also operate over unrestricted, regular values. To demonstrate the efficacy of our linear type system - both how easy it can be integrated in an existing language implementation and how streamlined it makes it to write programs with linear types - we implemented our type system in GHC, the leading Haskell compiler, and demonstrate two kinds of applications of linear types: mutable data with pure interfaces; and enforcing protocols in I/O-performing functions

Fisheye keyboard : whole keyboard displayed on small device

In this article, we propose a soft keyboard with interaction inspired by research on visualisation information. Our goal is to find a compromise between readability and usability on a whole character layout for an Ultra mobile PC. The proposed interactions allow to display all keys on a small screen while making pointing easier for the user by expanding any given key as a function of its distance from the stylus