La longue marche vers une appropriation cognitive du Web : le cas de la bande dessinée

International audienc

Internet et la promotion de la bande dessinée : quel rôle pour les réseaux sociaux ?

Date du colloque : 2011/12/02National audienc

Internet and the ‘Long Tail versus superstar effect’ debate: evidence from the French book market

From a comprehensive database of monthly sales of comic books and literature books in France over the period 2003 to 2007, we show that (i) bestsellers got smaller market shares online than offline, contrary to medium- and low-sellers; (ii) both online and offline sales shift from the head of the distribution to the tail with increasing magnitude over the period; and (iii) the Long Tail appears to be more than just a short-lived phenomenon caused by the specific preferences of early adopters of e-commerce. These three results suggest that online information and distribution tools, whose use increased over the period 2003 to 2007, do have an impact on book distribution and on consumers\u27 purchase decisions

Secular sea level change in the Russian sector of the Arctic Ocean

Author Posting. © American Geophysical Union, 2004. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research 109 (2004): C03042, doi:10.1029/2003JC002007.Sea level is a natural integral indicator of climate variability. It reflects changes in practically all dynamic and thermodynamic processes of terrestrial, oceanic, atmospheric, and cryospheric origin. The use of estimates of sea level rise as an indicator of climate change therefore incurs the difficulty that the inferred sea level change is the net result of many individual effects of environmental forcing. Since some of these effects may offset others, the cause of the sea level response to climate change remains somewhat uncertain. This paper is focused on an attempt to provide first-order answers to two questions, namely, what is the rate of sea level change in the Arctic Ocean, and furthermore, what is the role of each of the individual contributing factors to observed Arctic Ocean sea level change? In seeking answers to these questions we have discovered that during the period 1954–1989 the observed sea level over the Russian sector of the Arctic Ocean is rising at a rate of approximately 0.123 cm yr−1 and that after correction for the process of glacial isostatic adjustment this rate is approximately 0.185 cm yr−1. There are two major causes of this rise. The first is associated with the steric effect of ocean expansion. This effect is responsible for a contribution of approximately 0.064 cm yr−1 to the total rate of rise (35%). The second most important factor is related to the ongoing decrease of sea level atmospheric pressure over the Arctic Ocean, which contributes 0.056 cm yr−1, or approximately 30% of the net positive sea level trend. A third contribution to the sea level increase involves wind action and the increase of cyclonic winds over the Arctic Ocean, which leads to sea level rise at a rate of 0.018 cm yr−1 or approximately 10% of the total. The combined effect of the sea level rise due to an increase of river runoff and the sea level fall due to a negative trend in precipitation minus evaporation over the ocean is close to 0. For the Russian sector of the Arctic Ocean it therefore appears that approximately 25% of the trend of 0.185 cm yr−1, a contribution of 0.048 cm yr−1, may be due to the effect of increasing Arctic Ocean mass.This material is based upon work supported by the National Science Foundation under grant 0136432