Superconductivity in domains with corners

We study the two-dimensional Ginzburg-Landau functional in a domain with corners for exterior magnetic field strengths near the critical field where the transition from the superconducting to the normal state occurs. We discuss and clarify the definition of this field and obtain a complete asymptotic expansion for it in the large $\kappa$ regime. Furthermore, we discuss nucleation of superconductivity at the boundary

Outside-in disk evolution in the LMC

From the analysis of the color-magnitude diagrams and color functions of four wide LMC fields located from ~2 to 6 kpc from the kinematic center of the LMC we present evidence that, while the oldest population is coeval in all fields, the age of the youngest component of the dominant stellar population gradually increases with galactocentric distance, from currently active star formation in a field at 2.3 deg, to 100 Myr, 0.8 Gyr, and 1.5 Gyr in fields at 4.0 deg, 5.5 deg, and 7.1 deg, respectively. This outside-in quenching of the star formation in the LMC disk is correlated with the decreasing HI column density (which is < 2x 10^{20} cm^{-2} in the two outermost fields with little or no current star formation. Other work in the literature hints at similar behavior in the stellar populations of irregular galaxies, and in M33. This is observational evidence against the inside-out disk formation scenario in low-mass spirals and irregular galaxies. Alternatively, it could be that the age distribution with radius results from interplay between the evolution with time of the star-forming area of the LMC and the subsequent outward migration of the stars.Comment: 6 pages, 2 figures, ApJ Letters, in pres

Control of field- and current-driven magnetic domain wall motion by exchange bias in Cr2 O3/Co/Pt trilayers

We investigate the motion of magnetic domain walls driven by magnetic fields and current-driven spin-orbit torques in an exchange-biased system with perpendicular magnetization. We consider Cr2O3/Co/Pt trilayers as a model system, in which the magnetization of the Co layer can be exchanged biased out-of-plane or in-plane depending on the field-cooling direction. In field-driven experiments, the in-plane exchange bias favors the propagation of the domain walls with internal magnetization parallel to the exchange-bias field. In current-driven experiments, the domain walls propagate along the current direction, but the domain wall velocity increases and decreases symmetrically (antisymmetrically) for both current polarities when the exchange bias is parallel (perpendicular) to the current line. At zero external field, the exchange bias modifies the velocity of current-driven domain wall motion by a factor of 10. We also find that the exchange bias remains stable under external fields up to 15 kOe and nanosecond-long current pulses with current density up to 3.5 × 1012 A/m. Our results demonstrate versatile control of the domain wall motion by exchange bias, which is relevant to achieve field-free switching of the magnetization in perpendicular systems and current-driven manipulation of domain walls velocity in spintronic device

Cadmium accumulation and interactions with zinc, copper, and manganese, analysed by ICP-MS in a long-term Caco-2 TC7 cell model

The influence of long-term exposure to cadmium (Cd) on essential minerals was investigated using a Caco-2 TC7 cells and a multi-analytical tool: microwave digestion and inductively coupled plasma mass spectrometry. Intracellular levels, effects on cadmium accumulation, distribution, and reference concentration ranges of the following elements were determined: Na, Mg, Ca, Cr, Fe, Mn, Co, Ni, Cu, Zn, Mo, and Cd. Results showed that Caco-2 TC7 cells incubated long-term with cadmium concentrations ranging from 0 to 10 lmol Cd/l for 5 weeks exhibited a significant increase in cadmium accumulation. Furthermore, this accumulation was more marked in cells exposed long-term to cadmium compared with controls, and that this exposure resulted in a significant accumulation of copper and zinc but not of the other elements measured. Interactions of Cd with three elements: zinc, copper, and manganese were particularly studied. Exposed to 30 lmol/l of the element, manganese showed the highest inhibition and copper the lowest on cadmium intracellular accumulation but Zn, Cu, and Mn behave differently in terms of their mutual competition with Cd. Indeed, increasing cadmium in the culture medium resulted in a gradual and significant increase in the accumulation of zinc. There was a significant decrease in manganese from 5 lmol Cd/l exposure, and no variation was observed with copper. Abbreviation: AAS – Atomic absorption spectrometry; CRM– Certified reference material; PBS – Phosphate buffered saline without calcium and magnesium; DMEM – Dubelcco’s modified Eagle’s medium

The effects of LHC civil engineering on the SPS and LEP machines

The LHC will utilise much of the existing LEP infrastructure but will require many new surface buildings and several smaller underground structures, two new transfer tunnels from the SPS to the LHC an d two huge cavern complexes to house the ATLAS and CMS experiments. Excavation for the underground structures will start while LEP and SPS are running, causig the existing tunnels in close proximity t o move. The predicted movements are of sufficient amplitude to prevent machine oepration if no precautions are taken

Geometrical engineering of a two-bands Chern insulator in two dimensions with arbitrary topological index

Two-dimensional 2-bands insulators breaking time reversal symmetry can present topological phases indexed by a topological invariant called the Chern number. Here we first propose an efficient procedure to determine this topological index. This tool allows in principle to conceive 2-bands Hamiltonians with arbitrary Chern numbers. We apply our methodology to gradually construct a quantum anomalous Hall insulator (Chern insulator) which can be tuned through five topological phases indexed by the Chern numbers {0,+/-1,+/-2}. On a cylindrical finite geometry, such insulator can therefore sustain up to two edge states which we characterize analytically. From this non-trivial Chern insulator and its time reversed copy, we build a quantum spin Hall insulator and show how the phases with a +/-2 Chern index yield trivial Z2 insulating phases.Comment: 10 pages, 9 figure

Dynamique du couvert végétal à la périphérie du Parc W du Burkina Faso

L’objectif de cette étude est d’analyser la dynamique du couvert végétal du Parc W du Burkina Faso et sa périphérie à travers les images Landsat et NDVI. Les données utilisées sont des images Landsat de 1984, 1999 et 2015 de résolution 30 mètres et une série temporelle d’images MODIS NDVI-250 mètres de la période 2001-2015. Des données de références collectées à l’aide d’un GPS et des connaissances locales ont permis une classification supervisée des images Landsat à l’aide de l’algorithme de maximum de vraisemblance. Le test de Mann-Kendall a été appliqué à la série d’images NDVI pour évaluer la tendance évolutive de la végétation.Les résultats montrent que dans la zone hors parc, le couvert végétal a connu une nette régression. Cette régression s’est faite au profit des champs dont les superficies ont plus que doublé, passant de 20,2 % à 46,4 % entre 1984 et 2015. Ainsi, 88,1 %, 48,3 % et 52,2 % des superficies respectives de Botou, Diapaga et Tansarga sont affectées par la dégradation du couvert végétal. Selon le test de Mann-Kendal, 16,82 % de la zone d’étude ont une tendance négative significative de la végétation. Cette tendance est principalement localisée dans les zones à emprise agropastorale, puisque 7,88 % de ces superficies sont localisées dans des champs.The objective of this study is to analyse the dynamics of the vegetation cover of Burkina Faso’s W Park and its periphery through Landsat and NDVI images. The data used are Landsat images from 1984, 1999 and 2015 with a resolution of 30 meters and a time series of MODIS NDVI-250 meters images from the period 2001-2015. Reference data collected using GPS and local knowledge allowed a supervised classification of the Landsat images with the maximum likelihood algorithm. The Mann-Kendall test was applied to the NDVI time series to assess the vegetation trend.The results showed that in the area outside the park, the vegetation cover has clearly regressed. This regression was in favour of croplands whose area has more than doubled from 20.2% to 46.4% between 1984 and 2015. Thus, vegetation cover declined in 88.1%, 48.3% and 52.2% of the areas of Botou, Diapaga and Tansarga respectively. According to the Mann-Kendal test, 16.82% of the study area has a significant negative vegetation trend. This trend is mainly localized in the agropastoral zones, since 7.88% of these areas are located in fields

La culture du vanillier

We use observations of ice sheet surface motion from a Global Positioning System network operating from 2006 to 2014 around North Lake in west Greenland to investigate the dynamical response of the Greenland Ice Sheet's ablation area to interannual variability in surface melting. We find no statistically significant relationship between runoff season characteristics and ice flow velocities within a given year or season. Over the 7 year time series, annual velocities at North Lake decrease at an average rate of −0.9 ± 1.1 m yr−2, consistent with the negative trend in annual velocities observed in neighboring regions over recent decades. We find that net runoff integrated over several preceding years has a negative correlation with annual velocities, similar to findings from the two other available decadal records of ice velocity in western Greenland. However, we argue that this correlation is not necessarily evidence for a direct hydrologic mechanism acting on the timescale of multiple years but could be a statistical construct. Finally, we stress that neither the decadal slowdown trend nor the negative correlation between velocity and integrated runoff is predicted by current ice-sheet models, underscoring that these models do not yet capture all the relevant feedbacks between runoff and ice dynamics needed to predict long-term trends in ice sheet flow

DooSo6: Easy Collaboration over Shared Projects

International audienceExisting tools for supporting parallel work feature some disadvantages that prevent them to be widely used. Very often they require a complex installation and creation of accounts for all group members. Users need to learn and deal with complex commands for efficiently using these collaborative tools. Some tools require users to abandon their favourite editors and impose them to use a certain co-authorship application. In this paper, we propose the DooSo6 collaboration tool that offers support for parallel work, requires no installation, no creation of accounts and that is easy to use, users being able to continue working with their favourite editors. User authentication is achieved by means of a capability-based mechanism