Can multimarket competition theory explain why manufacturers are reluctant to adopt e-commerce ? The case of the French household appliances’ manufacturers

International audienceWith turnover of more than €51 billion in France in 2013, e-commerce continues to grow, both in volume and number of players. While economic theories suggest that manufacturers should integrate intermediation functions as soon as they are able to perform them at a lower cost than external operators, few French manufacturers are engaging in e-commerce. In this research, we explore why manufacturers of household appliance do not launch e-commerce sites. Our results suggest that, in accordance with multimarket competition theory, they do so in order to avoid coercion from the traditional French distribution system

Hydration of casein micelles: kinetics and isotherms of water sorption of micellar casein isolated from fresh and heat-treated milk

Water vapour sorption isotherms of casein micelles prepared from raw milk and various heat-treated milks were determined. The equilibrium water contents of the heated preparations were markedly lower than that of the raw-milk casein over the whole range of vapour pressures studied. An analysis of the sorption isotherms in the relative vapour pressure range 0·1-0.45, according to the Brunauer, Emmett & Teller (1938) equation, showed that there were significant differences between preparations in the computed monolayer contents. Differences in the rates of water sorption were also observed between the different preparations. As judged from the amount of absorbed water, the influence of the heating methods could be ranked in the order: HTST (92 °C) UHT (direct) <UHT (indirect) < HTST (72 °C

Intérêt de l’utilisation de la photogrammétrie SfM (Structure from Motion) pour le suivi des processus nivo-glaciaires. Application au bassin du glacier Austre Lovén, Spitsberg

National audienceL’Arctique est reconnu comme un ex¬cellent indicateur des évolutions clima¬tiques contemporaines : sa sensibilité aux moindres sollicitations climatiques en fait une zone d’étude idéale. L’étude des pro¬cessus et des dynamiques glaciaires revêt, dans ce contexte, un intérêt majeur afin de mieux comprendre les impacts du climat sur la récession glaciaire observée durant cette dernière décade

Assessing the relevance of digital elevation models to evaluate glacier mass balance : application to Austre Lovénbreen (Spitsbergen, 79 ° N)

International audienceThe volume variation of a glacier is the actual indicator of long term and short term evolution of the glacier behaviour. In order to assess the volume evolution of the Austre Lovénbreen (79 • N) over the last 47 years, we used multiple historical datasets, complemented with our high density GPS tracks acquired in 2007 and 2010. The improved altitude resolution of recent measurement techniques, including phase corrected GPS and LiDAR, reduces the time interval between datasets used for volume subtraction in order to compute the mass balance. We estimate the sub-metre elevation accuracy of most recent measurement techniques to be sufficient to record ice thickness evolutions occurring over a 3 year duration at polar latitudes. The systematic discrepancy between ablation stake measurements and DEM analysis, widely reported in the literature as well as in the current study, yields new questions concerning the similarity and relationship between these two measurement methods. The use of Digital Elevation Model (DEM) has been an attractive alternative measurement technique to estimate glacier area and volume evolution over time with respect to the classical in situ measurement techniques based on ablation stakes. With the availability of historical datasets, whether from ground based maps, aerial photography or satellite data acquisition, such a glacier volume estimate strategy allows for the extension of the analysis duration beyond the current research programmes. Furthermore, these methods do provide a continuous spatial coverage defined by its cell size whereas interpolations based on a limited number of stakes display large spatial uncertainties. In this document, we focus on estimating the altitude accuracy of various datasets acquired between 1962 and 2010, using various techniques ranging from topographic maps to dual frequency skidoo-tracked GPS receivers and the classical aerial and satellite photogrammetric techniques

Where does a glacier end ? GPR measurements to identify the limits between the slopes and the real glacier area. Application to the Austre Lovénbreen, Spitsbergen -- 79°N

International audienceGlacier limits are usually mapped according to a spatial discrimination based on color of remote sensing images or aerial photography. What appears like ice (white or light colored areas) at the end of the ablation period (end of summer) corresponds to the glacier, while what appears as rock (dark areas) is identified as the slope. This kind of visual discretization seems to be insufficient in the case of small arctic glaciers. Indeed, the slopes have been described as very unstable parts of glacial basins. Debris are generated by the inclination of the slopes, and reach the glacier surface. Thus, the visible limit does not correspond to the ice extension: a significant amount of ice is potentially covered by rock debris, enlarging the actual glacier surface with respect to the observed area. Hence, we apply Ground Penetrating Radar (GPR) measurements for mapping, beyond the central parts of the glacier, the steep slopes of the Austre Lovénbreen (Spitsbergen, 79°N). The aim is to assess the discrepancy between the limits extracted from remote sensing methods -- aerial photography, satellite images and derived digital elevation models -- and the GPR data which exhibit significant ice thickness at locations considered outside the glacier itself. The ice is observed to extend typically from 25 to 30 meters, and up to 100~meters, under the slopes. These measurements allow for a new determination of the rock/ice interface location following criteria beyond the visual and morphological characteristics seen from the surface, as obtained by remote sensing techniques or in-situ observations

Approche multivariée des facteurs influençant le bilan de masse d’un glacier arctique

National audienceL’Arctique est la zone géographique où la modification du climat au cours du XXIieme siècle sera la plus forte de la planète. La totalité de la cryosphère (banquise, glaciers, pergélisol, etc.) subira de profondes altérations qui se traduiront spatialement par des évolutions majeures. Les glaciers sont de bons indicateurs de ces changements, aussi bien à une échelle locale que globale, car leur dynamique est très sensible au climat. Cette étude porte sur un glacierdu Spitsberg où il a été observé que des conditions climatiques et nivologiques contrastées d’une année sur l’autre avaient des conséquences multiples, et parfois inattendues, sur les bilans de masse

High density coverage investigation of The Austre LovénBreen (Svalbard) using Ground Penetrating Radar

COMInternational audienceA three week field survey over April 2010 allowed for the acquisition of 120 Ground Penetrating Radar (GPR) profiles, adding to a 40 km long walk across an Arctic glacier. The profiles were acquired using a Mal°a equipment with 100 MHz antennas, walking slowly enough to record a 2.224 s trace every 30 cm on the average. Some acquisitions were repeated with 50 MHz or 200 MHz antenna to improve data quality. The GPR was coupled to a GPS system to position traces. Each profile has been manually edited using standard GPR data processing, to pick the reflection arrival time from the ice-bedrock interface. Traveltimes were converted to ice thickness using a velocity of 0.17 m/ns. Dual-frequency GPS mapping and snow coverage thickness were acquired during the same survey. Using interpolation methods, we derived the underlying bedrock topography and evaluated the ice volume

Monitoring seasonal snow dynamics using ground based high resolution photography (Austre Lovenbreen, Svalbard, 79°N)

International audienceArctic glaciers are reliable indicators of global climate changes. However, monitoring snow and ice dynamics in Arctic regions is challenging: some fast but key events can be missed since they are short in time but significant in the hydrological budget. In the context of long term monitoring with high temporal and spatial resolutions of the snow cover dynamics, automated digital cameras were installed around the Austre Lovénbreen glacier basin (Spitsbergen, Norway, 79 N). Despite data losses due to rough weather conditions and control electronics failure, a dataset of 2411 pictures (out of an expected 3294) was gathered over a 1 year hydrological period to assess the snow coverage of the glacier as a function of time with daily resolution. 73% of the total number of expected images was thus recorded, with gaps associated with temporary electronics or data storage failure. The six camera stations oriented so as to observe the glacier itself provide a surface coverage of 96%. Furthermore, geometric corrections of the pictures, using reference ground control points located on the glacier through GPS receivers, yield a quantitative information from initially qualitative images. Projecting the resulting mosaic of the images gathered from six cameras on a GIS allows for the precise monitoring of ice-related processes, and especially the snow coverage evolution over time. This paper summarizes our current understanding of such dynamics, based on the analysis of daily mosaics of images allowing for the observation of both long term evolution on the seasonal scale and the short term events on a weekly scale. Such results demonstrated over one typical full hydrological season (April-October 2009) that snow coverage evolves following discrete steps, either due to water precipitation or warm events, with a snow coverage ranging from 100% (april) to 37% (September

Deriving ice thickness, glacier volume and bedrock morphology of the Austre Lovénbreen (Svalbard) using Ground-penetrating Radar

International audienceThe Austre Lovénbreen is a 4.6 km2 glacier on the Archipelago of Svalbard (79°N) that has been surveyed over the last 47 years in order of monitoring in particular the glacier evolution and associated hydrological phenomena in the context of nowadays global warming. A three-week field survey over April 2010 allowed for the acquisition of a dense mesh of Ground-penetrating Radar (GPR) data with an average of 14683 points per km2 (67542 points total) on the glacier surface. The profiles were acquired using a Mala equipment with 100 MHz antennas, towed slowly enough to record on average every 0.3 m, a trace long enough to sound down to 189 m of ice. One profile was repeated with 50 MHz antenna to improve electromagnetic wave propagation depth in scattering media observed in the cirques closest to the slopes. The GPR was coupled to a GPS system to position traces. Each profile has been manually edited using standard GPR data processing including migration, to pick the reflection arrival time from the ice-bedrock interface. Snow cover was evaluated through 42 snow drilling measurements regularly spaced to cover all the glacier. These data were acquired at the time of the GPR survey and subsequently spatially interpolated using ordinary kriging. Using a snow velocity of 0.22 m/ns, the snow thickness was converted to electromagnetic wave travel-times and subtracted from the picked travel-times to the ice-bedrock interface. The resulting travel-times were converted to ice thickness using a velocity of 0.17 m/ns. The velocity uncertainty is discussed from a common mid-point profile analysis. A total of 67542 georeferenced data points with GPR-derived ice thicknesses, in addition to a glacier boundary line derived from satellite images taken during summer, were interpolated over the entire glacier surface using kriging with a 10 m grid size. Some uncertainty analysis were carried on and we calculated an averaged ice thickness of 76 m and a maximum depth of 164 m with a relative error of 11.9%. The volume of the glacier is derived as 0.3487±0.041 km3. Finally a 10-m grid map of the bedrock topography was derived by subtracting the ice thicknesses from a dual-frequency GPS-derived digital elevation model of the surface. These two datasets are the first step for modelling thermal evolution of the glacier and its bedrock, as well as the main hydrological network

Contrasting effects of peroxisome-proliferator-activated receptor (PPAR)γ agonists on membrane-associated prostaglandin E(2 )synthase-1 in IL-1β-stimulated rat chondrocytes: evidence for PPARγ-independent inhibition by 15-deoxy-Δ(12,14)prostaglandin J(2)

Microsomal prostaglandin E synthase (mPGES)-1 is a newly identified inducible enzyme of the arachidonic acid cascade with a key function in prostaglandin (PG)E(2 )synthesis. We investigated the kinetics of inducible cyclo-oxygenase (COX)-2 and mPGES-1 expression with respect to the production of 6-keto-PGF(1α )and PGE(2 )in rat chondrocytes stimulated with 10 ng/ml IL-1β, and compared their modulation by peroxisome-proliferator-activated receptor (PPAR)γ agonists. Real-time PCR analysis showed that IL-1β induced COX-2 expression maximally (37-fold) at 12 hours and mPGES-1 expression maximally (68-fold) at 24 hours. Levels of 6-keto-PGF(1α )and PGE(2 )peaked 24 hours after stimulation with IL-1β; the induction of PGE(2 )was greater (11-fold versus 70-fold, respectively). The cyclopentenone 15-deoxy-Δ(12,14)prostaglandin J(2 )(15d-PGJ(2)) decreased prostaglandin synthesis in a dose-dependent manner (0.1 to 10 μM), with more potency on PGE(2 )level than on 6-keto-PGF(1α )level (-90% versus -66% at 10 μM). A high dose of 15d-PGJ(2 )partly decreased COX-2 expression but decreased mPGES-1 expression almost completely at both the mRNA and protein levels. Rosiglitazone was poorly effective on these parameters even at 10 μM. Inhibitory effects of 10 μM 15d-PGJ(2 )were neither reduced by PPARγ blockade with GW-9662 nor enhanced by PPARγ overexpression, supporting a PPARγ-independent mechanism. EMSA and TransAM(® )analyses demonstrated that mutated IκBα almost completely suppressed the stimulating effect of IL-1β on mPGES-1 expression and PGE(2 )production, whereas 15d-PGJ(2 )inhibited NF-κB transactivation. These data demonstrate the following in IL-1-stimulated rat chondrocytes: first, mPGES-1 is rate limiting for PGE(2 )synthesis; second, activation of the prostaglandin cascade requires NF-κB activation; third, 15d-PGJ(2 )strongly inhibits the synthesis of prostaglandins, in contrast with rosiglitazone; fourth, inhibition by 15d-PGJ(2 )occurs independently of PPARγ through inhibition of the NF-κB pathway; fifth, mPGES-1 is the main target of 15d-PGJ(2)