À partir de contributions d'Antoine-César Becquerel (1853-1865), une étude économétrique du marché du blé en France de 1815 à 1863

Dans deux Mémoires publiés en 1853 et 1865, A.-C. Becquerel a étudié le marché du blé en France en en dégageant les évolutions de long terme et en analysant les fluctuations de la récolte et du prix. L\u27article présente d\u27abord ces travaux novateurs en les situant par rapport aux recherches de leur époque et en en montrant les insuffisances. Les données statistiques rassemblées par Becquerel sont ensuite traitées à l\u27aide de différentes techniques économétriques, modèle à correction d\u27erreurs, modèle VAR, analyse spectrale. Si les deux dernières techniques montrent peu de liaisons entre les évolutions des différentes variables, le modèle à correction d\u27erreurs montre que l\u27on peut expliquer les variations du prix du blé à partir des variations de la superficie ensemencée en blé et du rendement en blé à l\u27hectare, ce qui rejoint les explications en termes de cycles de récoltes proposées par de nombreux économistes et agronomes au XIXe siècle

Déficits commerciaux et désindustrialisation en Europe : une étude comparée de l’Espagne, l’Italie et la France

International audienc

Une contribution ignorée d’Antoine-César Becquerel : l’analyse économétrique du marché du blé en France

International audienc

La Croatie dans l’Union Européenne : une insertion différenciée

International audienc

Le songe biblique comme hypothèse heuristique : le songe des vaches maigres et des vaches grasses et les analyses de la périodicité des mouvements du prix du blé

Depuis 1850, le songe biblique des vaches grasses et des vaches maigres est utilisé dans l\u27étude de la périodicité des récoltes. Ainsi, Hugo (1853), Briaune (1857) et Duffaud (1862) fondent sur lui leurs analyses de la périodicité. Cette démarche est rejetée par Benner (1875), Leslie (1864) et Juglar (1889). Plus tard, Mandelbrot (1968 fonde sur ce songe et la statistique des crues du Nil l\u27étude de la mémoire longue dans les séries temporelles. L\u27analogie est confirmée en comparant la série de prix utilisée par Duffaud à une série des niveaux du Nil

Trade Elasticities and De-industrialization Phenomena in Europe: Case Studies in Spain, Italy and France

The number of member States in the European Union has been growing for the last 20 years and now includes 28 countries. The euro zone includes 19 countries, some of which (especially Greece, Spain or Portugal) have important price-competitiveness problems. Despite the EMU mechanism and the free movement of capital assets in Europe, which was supposed to help countries reach high competitiveness, some European countries, mostly the countries of the South of Europe, today suffer from a big trade deficit. The aim of this paper is to explain the cause of these deficits and especially to answer the question of the long run specialisation weakness or the short run competitiveness weakness. We compute export price elasticities and income elasticities of four European countries (France, Germany, Spain, and Italy) to analyse the Southern European countries’ hardship caused by structural, institutional, or conjectural problems with their trade balance? The key question deals with industrial deficits and the de-industrialisation phenomena throughout Europe. Are industrial sectors necessary for the increase in economic performances among international markets? Must all European countries specialise in industrial sectors only, in order to export? But if we enlarge the analysis to take into account the service exports (such as travel or firms services), it will be possible to link service exports and industrial exports in a positive dynamic

Seismic Constraints on the Thickness and Structure of the Martian Crust from InSight

NASA¿s InSight mission [1] has for the first time placed a very broad-band seismometer on the surface of Mars. The Seismic Experiment for Interior Structure (SEIS) [2] has been collecting continuous data since early February 2019. The main focus of InSight is to enhance our understanding of the internal structure and dynamics of Mars, which includes the goal to better constrain the crustal thickness of the planet [3]. Knowing the present-day crustal thickness of Mars has important implications for its thermal evolution [4] as well as for the partitioning of silicates and heat-producing elements between the different layers of Mars. Current estimates for the crustal thickness of Mars are based on modeling the relationship between topography and gravity [5,6], but these studies rely on different assumptions, e.g. on the density of the crust and upper mantle, or the bulk silicate composition of the planet and the crust. The resulting values for the average crustal thickness differ by more than 100%, from 30 km to more than 100 km [7]. New independent constraints from InSight will be based on seismically determining the crustal thickness at the landing site. This single firm measurement of crustal thickness at one point on the planet will allow to constrain both the average crustal thickness of Mars as well as thickness variations across the planet when combined with constraints from gravity and topography [8]. Here we describe the determination of the crustal structure and thickness at the InSight landing site based on seismic receiver functions for three marsquakes compared with autocorrelations of InSight data [9].We acknowledge NASA, CNES, partner agencies and institutions (UKSA, SSO,DLR, JPL, IPGP-CNRS, ETHZ, IC, MPS-MPG) and the operators of JPL, SISMOC, MSDS, IRIS-DMC and PDS for providing SEED SEIS data. InSight data is archived in the PDS, and a full list of archives in the Geosciences, Atmospheres, and Imaging nodes is at https://pds-geosciences.wustl.edu/missions/insight/. This work was partially carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration. ©2021, California Institute of Technology. Government sponsorship acknowledge

The interior of Mars as seen by InSight (Invited)

InSight is the first planetary mission dedicated to exploring the whole interior of a planet using geophysical methods, specifically seismology and geodesy. To this end, we observed seismic waves of distant marsquakes and inverted for interior models using differential travel times of phases reflected at the surface (PP, SS...) or the core mantle-boundary (ScS), as well as those converted at crustal interfaces. Compared to previous orbital observations1-3, the seismic data added decisive new insights with consequences for the formation of Mars: The global average crustal thickness of 24-75 km is at the low end of pre-mission estimates5. Together with the the thick lithosphere of 450-600 km5, this requires an enrichment of heat-producing elements in the crust by a factor of 13-20, compared to the primitive mantle. The iron-rich liquid core is 1790-1870 km in radius6, which rules out the existence of an insulating bridgmanite-dominated lower mantle on Mars. The large, and therefore low-density core needs a high amount of light elements. Given the geochemical boundary conditions, Sulfur alone cannot explain the estimated density of ~6 g/cm3 and volatile elements, such as oxygen, carbon or hydrogen are needed in significant amounts. This observation is difficult to reconcile with classical models of late formation from the same material as Earth. We also give an overview of open questions after three years of InSight operation on the surface of Mars, such as the potential existence of an inner core or compositional layers above the CM

Constraints on the shallow elastic and anelastic structure of Mars from InSight seismic data

Mars’s seismic activity and noise have been monitored since January 2019 by the seismometer of the InSight (Interior Exploration using Seismic Investigations, Geodesy and Heat Transport) lander. At night, Mars is extremely quiet; seismic noise is about 500 times lower than Earth’s microseismic noise at periods between 4 s and 30 s. The recorded seismic noise increases during the day due to ground deformations induced by convective atmospheric vortices and ground-transferred wind-generated lander noise. Here we constrain properties of the crust beneath InSight, using signals from atmospheric vortices and from the hammering of InSight’s Heat Flow and Physical Properties (HP3) instrument, as well as the three largest Marsquakes detected as of September 2019. From receiver function analysis, we infer that the uppermost 8–11 km of the crust is highly altered and/ or fractured. We measure the crustal diffusivity and intrinsic attenuation using multiscattering analysis and find that seismic attenuation is about three times larger than on the Moon, which suggests that the crust contains small amounts of volatiles