Search results for "tiques"
showing 10 items of 1274 documents
Experimental demonstration of phase bistability in a broad-area optical oscillator with injected signal
2015
We demonstrate experimentally that a broad-area laserlike optical oscillator (a nondegenerate photorefractive oscillator) with structured injected signal displays two-phase patterns. The technique [de Valc\'arcel and Staliunas, Phys. Rev. Lett. 105, 054101 (2010)] consists in spatially modulating the injection, so that its phase alternates periodically between two opposite values, i.e., differing by $\ensuremath{\pi}$.
Connectivity percolation in suspensions of hard platelets
2012
We present a study on connectivity percolation in suspensions of hard platelets by means of Monte Carlo simulation. We interpret our results using a contact-volume argument based on an effective single--particle cell model. It is commonly assumed that the percolation threshold of anisotropic objects scales as their inverse aspect ratio. While this rule has been shown to hold for rod-like particles, we find that for hard plate-like particles the percolation threshold is non-monotonic in the aspect ratio. It exhibits a shallow minimum at intermediate aspect ratios and then saturates to a constant value. This effect is caused by the isotropic-nematic transition pre-empting the percolation tran…
Microwave and optical data fusion for global mapping of soil moisture at high resolution
2018
After more than 8 years in orbit the Soil Moisture and Ocean Salinity (SMOS) satellite is still in good health and several algorithms for improving its spatial resolution have been proposed and validated in a variety of catchments. However, none of them has yet been applied at the global scale. In this article we present: i) a review of the latest SMOS-BEC downscaling algorithm, which allows for its global application using an adaptive moving window and ii) a thorough validation of the resulting maps over two in-situ networks: REMEDHUS in Spain and OzNet in Australia. The proposed algorithm combines SMOS brightness temperatures (at ~40 km spatial resolution), and MODIS-derived Land Surface …
Cartographie des restes osseux et conservation différentielle dans l'amas coquillier d'Ouessant "Mez Notariou": du Bronze moyen à la période romaine
2008
This article addresses the impacts of differential preservation in an alkaline shell midden (fig. 1) overlying an acid soil which does not allow bone to survive. This midden accumulated over an extended period and displays unusual traits attributable to practices of a ritual nature (Le Bihan et Méniel, 2002). Excavation extended to approximately 1000 square metres (fig. 2). Bone was collected on a quarter-metre grid by individual context (fig. 3). Some 35,000 animal and bird bones were recovered; fish bones, which were very numerous, are presently still under study. Consideration of the entire bone assemblage (fig. 8) indicates that the principal deposition occurred along the SW/NE axis of …
Effect of two novel bio-based rejuvenators on the performance of 50% RAP mixes - a statistical study on the complex modulus of asphalt binders and as…
2019
An experimental study was conducted to evaluate the effectiveness of two bio-additives as rejuvenators on the properties of asphalt mixtures containing 50% RAP and their binder constituents containing 37% RAP binder. Before mixing, the rejuvenators were blended with fresh bitumen and the extracted and recovered RAP bitumen, and changes in the rheological properties of the binders were assessed using performance grading (PG) criteria. The results showed that both rejuvenators could improve the low-temperature performance of the aged RAP binder and restore its low-temperature properties. Master curves for the unaged, RTFO-aged, and PAV aged blends were constructed using both the Christensen-A…
Estimation of the degrading genetic potential of soil bacterial communities: a new tool for evaluating and predicting soil contamination by organic m…
2007
During the last two centuries, industrialisation has led to increasing contamination of the environment by xenobiotics, notably aromatic compounds (i.e. PAHs, pesticides). These widespread pollutants are a major threat affecting soil quality and human health. In this context, numerous policies have been drawn up notably in Europe, to monitor the threats of pollution to ecosystems and to detect and implement measures to counterbalance the damage. Nevertheless, the European Commission and scientific community are still confronted with a lack of appropriate tools to monitor biodiversity in relation to environmental processes affecting global warming and soil protection. This study proposes too…
(no title)
1999
We propose hereafter that the signature of the Space-Time metric (+++-) is not anymore frozen at the Planck scale and presents quantum fluctuations (+++±) untill 0 scale where it becomes Euclidean (++++). (i) At the albraic level we suggest an oscillation path (3,1) (4,0) exluding (2,2). We built the quotient topological space describing the superposition of the Lorentzian and the Riemanian metrics. In terms of quantum groups we evidence a relation between q-deformation and deformation of the signature. We have obtained a new algebraic construction ( a new cocycle bicross products by twisting) which allowed us to unify the Lorentzian and the Euclidean signatures within a unique quantum grou…
From resurgent functions to real resummation through combinatorial Hopf algebras
2014
Pas de résumé en anglais.
SMOS REFLEX 2003: L-band emissivity characterization of vineyards
2005
The goal of the Soil Moisture and Ocean Salinity mission over land is to infer surface soil moisture from multiangular L-band radiometric measurements. As the canopy affects the microwave emission of land, it is necessary to characterize different vegetation layers. This paper presents the Reference Pixel L-Band Experiment (REFLEX), carried out in June-July 2003 at the Vale/spl grave/ncia Anchor Station, Spain, to study the effects of grapevines on the soil emission and on the soil moisture retrieval. A wide range of soil moisture (SM), from saturated to completely dry soil, was measured with the Universitat Polite/spl grave/cnica de Catalunya's L-band Automatic Radiometer (LAURA). Concurre…
Global L-band vegetation volume fraction estimates for modeling vegetation optical depth
2021
The attenuation of microwave emissions through the canopy is quantified by the vegetation optical depth (VOD), which is related to the amount of water, the biomass and the structure of vegetation. To provide microwave-derived plant water estimates, one must account for biomass/structure contributions in order to extract the water component from the VOD. This study uses Aquarius scatterometer data to build an L-band global seasonality of vegetation volume fraction (d), representative of biomass/structure dynamics. The dynamic range of d is adapted for its application in a gravimetric moisture (Mg) retrieval model. Results show that d ranging from 0 to 3.35.10- 4 is needed for modelling physi…