Matching frictions and the divide of schooling investment between general and specific skills

This paper examines the impact of labor market frictions and institutions on the divide of schooling investment between general and specific skills. We offer a simple matching model of unemployment in which individuals determine the scope and intensity of their skills. In partial equilibrium, we show that the severity of market frictions distorts the schooling allocation towards more general skills. Then, we endogenize job creation and argue that changes in labor market institutions may well originate a non-monotonous relationship between unemployment and the divide of skills between specific and general human capital. We also investigate more carefully the impacts of unemployment compensation, minimum wage and firing costs. We suggest that unemployment compensation has an ambiguous impact on the skill divide, while minimum wage and firing costs are detrimental to general skill acquisition.Matching frictions; education; general and specific skills; labour market institutions

Holostratigraphy of the Kahmah regional Series in Oman, Qatar, and the United Arab Emirates

International audienceThe stratigraphic framework of the uppermost Jurassic - Lower Cretaceous interval of the Gulf area is revised using both historical and recently acquired paleontological (ammonites, calpionellids, foraminifers, 'calcareous' algae), sedimentological and sequential information. The Kahmah regional Series ranging in age from Late Tithonian to Gargasian (= middle Aptian) times is subdivided into regional stages, named from bottom to top: Rayda (with two substages, Bu Haseer and Belbazem), Salil, Zakum, Lekhwair, Kharaib, Hawar, and Shu'aiba. The Kahmah rests either on strata representing the Habshan regional Stage, which is the last term of the Sahtan regional Series (locally absent due to a stratigraphic hiatus in basinal areas), or on much older strata; it is followed either by the Bab regional Stage (locally absent due to a stratigraphic hiatus on platform areas), or by the Sabsab regional Substage (the lowermost part of the Nahr Umr regional Stage), both of which are assigned the Wasi'a regional Series. The Kahmah succession (as well as those of the Sahtan below and the Wasi'a above) is discontinuous, i.e. punctuated by sedimentary hiatuses due to forced regressions, some of significant importance (in the Zakum or in the Bab, and those bounding the Hawar and the Shu'aiba)

A microfoundation for adaptability returns to schooling and technological complexity

In a frictional environment, technological complexity creates adaptability returns to schooling. This paper provides microfoundations to such an argument, and revisits the impacts of worker heterogeneity and risk aversion. In our model, firms and workers are located on a knowledge space. Education widens the measure of the knowledge subset that the worker embodies, while technological complexity expands the measure of the knowledge subset that is required to operate on the job. We find uncertainty with regard to the type of the future partner motivates schooling, while it inhibits technological complexity. When workers differ in scholastic ability, the welfare of a given group increases with the proportion of workers of this group. Finally, risk aversion motivates a precautionary demand for education, which in turn creates income risk through firms' technological choices.Education; Multi-dimensional skills; Frictions; Heterogeneity; Risk aversion

Adaptability vs complexity: on the efficiency of educational and technological choices

European labour markets have known three major changes over the past three decades : the complexification of the technological environment, the growth of general education across the workforce, and rising unemployment. Taken together, do these facts reflect the inefficiency of schooling and technological decisions ? Our answer takes place in a matching model of unemployment in which firms choose technological complexity, and workers educate to improve their adaptability. We show economic policy should focus on the labour market and the education system rather than on firms’ technological choices.Matching frictions; Heterogeneity; Ex-ante investment

A microfoundation for adaptability returns to schooling and technological complexity

In a frictional environment, technological complexity creates adaptability returns to schooling. This paper provides microfoundations to such an argument, and revisits the impacts of worker heterogeneity and risk aversion. In our model, firms and workers are located on a knowledge space. Education widens the measure of the knowledge subset that the worker embodies, while technological complexity expands the measure of the knowledge subset that is required to operate on the job. We find uncertainty with regard to the type of the future partner motivates schooling, while it inhibits technological complexity. When workers differ in scholastic ability, the welfare of a given group increases with the proportion of workers of this group. Finally, risk aversion motivates a precautionary demand for education, which in turn creates income risk through firms' technological choices

Cretaceous Roveacrinids from Mexico revisited: Overcoming the taxonomic misidentifications and subsequent biostratigraphic abuse

The Mesozoic carbonate deposits of Mexico yield a number of overlooked, ill-known, and even enigmatic microfossils, among which are roveacrinoids (Echinodermata, Crinoidea, Roveacrinida). Most of these pelagic organisms probably came from the central Tethysian seaways, and later on from the early central Atlantic Ocean through the northwestern Tethysian neck, thus reaching the Central American platforms (Comanchean shelf, Central Texas platform, and Coahuila platform) and the Western Interior seaway. The present work intends to enlist as comprehensively as possible the Mexican records of roveacrinid crinoids, to propose a revised interpretation of the sections illustrated (most of them being originally erroneously assigned) and to provide a sound data base for further systematic and biostratigraphic research

Falsolikanella danilovae RADOIČIĆ ex BARATTOLO 1978, n. comb., a diploporacean alga from the Urgonian facies

International audienceOriginally described as Likanella danilovae RADOIČIĆ 1969, nom. nud., the species partly revisited hereafter has been lately ascribed to the genus Praturlonella BARATTOLO 1978 and validly published under this new combination. This short paper aims to demonstrate that it should be referred to the genus Falsolikanella GRANIER 1987

Perforations et corrosion dans l'oolithe du Bathonien supérieur - Callovien inférieur du Bassin de Paris (France)

The oolite of the "Dalle Nacrée" Formation in the Paris Basin is made of marine calcareous ooids with, from base to top, radial (and therefore likely to have been calcite), concentric and micritic fabrics, each corresponding to a discrete stratigraphic unit. Several hardgrounds and oolitic pebble-cobble layers in the succession are encrusted and bored. Three main types of boring have been identified ranging in sizes from some tens of µm (sponge borings) to centimeters (bivalve borings), with an intermediate category (worm borings). Some worm borings have rough walls, where early marine fibrous cement is less corroded than the cortices of cemented ooids. The key to understanding this differential dissolution could be related to organic matter, present within the ooid cortices but lacking in the fibrous cement. Polychaete worms that use chemical means (enzymes or acids) to bore are probably responsible for these peculiar borings. A secondary conclusion is that partly or fully leached ooid cortices do not necessarily indicate an original aragonitic mineralogy of the dissolved parts.L'oolite de la Formation de la "Dalle Nacrée" du bassin de Paris est constituée d'ooïdes calcaires marins avec, de bas en haut, des textures radiaire (et par conséquent vraisemblablement calcitiques à l'origine), concentrique et micritique, correspondant chacune à une unité stratigraphique distincte. Plusieurs fonds durcis et niveaux à graviers et galets oolithiques observés dans la succession sont encroûtés et perforés. Les trois principaux types de perforation identifiés ont des dimensions allant de quelques dizaines de micromètres (perforations d'éponges) à quelques centimètres (perforations de pélécypodes), avec une catégorie intermédiaire (perforations de vers). Quelques perforations de vers ont des parois présentant des aspérités, là où le ciment précoce marin est moins corrodé que les cortex des ooïdes qu'il cimente. La clef pour comprendre cette dissolution différentielle pourrait être liée à la matière organique, présente dans les cortex oolithiques mais absente du ciment fibreux. Les vers polychètes qui utilisent des moyens chimiques (enzymes ou acides) pour perforer sont probablement responsables de ces perforations singulières. Une seconde conclusion est que la dissolution partielle ou complète de cortex oolithiques n'implique pas nécessairement qu'à l'origine ces parties dissoutes étaient aragonitiques

Révision de l' Heteroporella ? paucicalcarea (CONRAD, 1970), une algue dasycladale urgonienne

À sa création l'espèce Heteroporella ? paucicalcarea (CONRAD, 1970) a été laissée en nomenclature ouverte. Ultérieurement de nouvelles combinaisons ont été proposées mais aucune n'a rencontrée l'unanimité parmi les paléophycologues. Compte-tenu de l'acception actuelle des familles d'algues dasycladales, nous rapportons ce taxon à la Famille des Polyphysaceae et par contre-coup au genre Clypeina (MICHELIN, 1845). Sa répartition stratigraphique connue est plutôt courte (Hauterivien supérieur-Barrémien inférieur), ce qui en fait un bon marqueur fossile dans les séries de plates-formes carbonatées urgoniennes. Sa distribution géographique est apparemment réduite à l'Europe occidentale (Espagne, France et Suisse).When the species Heteroporella ? paucicalcarea (CONRAD, 1970) was erected it was left in open nomenclature. Later on new combinations were introduced but did not meet a general agreement among paleophycologists. Considering the current acception of the Dasycladalean families, we ascribe it to the Family Polyphysaceae and subsequently to the genus Clypeina (MICHELIN, 1845). Its known stratigraphic range is rather brief (Late Hauterivian-Early Barremian), which makes it a good index fossil in Urgonian carbonate platform series. Its geographical distribution is apparently restricted to Western Europe (France, Spain and Switzerland)

Nouveau modèle stratigraphique et génétique pour les réservoirs dolomitiques du Pinda (Crétacé, Angola). IIe Partie – Preuves irréfutables contre une dolomitization et une dissolution précoces

This is the second contribution to the stratigraphic and genetic model of the Pinda Group. The mid-Cretaceous Pinda Group of the Congo basin in the northern Angolan offshore is a transgressive supersequence. Its lower part is made of Bufalo and Pacassa facies that correspond respectively to mixed and calcareous-dolomitic grain-dominated fabrics. Both facies were strongly diagenetically altered, mostly by dolomitic replacement and leaching. Contrary to opinions expressed by other authors that both styles of alteration are early diagenetic phenomena, there is substantial evidence for a burial origin with dolomitic replacement and leaching of calcite having started at depths not less than 150 m and 400 m, respectively.Il s'agit ici de la deuxième contribution au modèle génétique et stratigraphique du Pinda. Le Groupe Pinda du Crétacé moyen constitue une mégaquence transgressive au large de la partie septentrionale de l'Angola dans le bassin du Congo. Sa partie inférieure est constituée par les faciès Búfalo et Pacassa qui correspondent respectivement à des roches sédimentaires mixtes et calcaires-dolomitiques à dominante grenue. Ces deux types de sédiments ont subi de fortes altérations diagénétiques, essentiellement par du remplacement de la calcite par de la dolomite et par dissolution de la calcite restante. Contrairement aux opinions exprimées par d'autres auteurs selon lesquelles ces processus sont attribuables à une diagénèse précoce, il existe un faisceau d'arguments solides en faveur d'une origine liée au processus d'enfouissement avec notamment un remplacement par de la dolomite et de la dissolution ayant débuté respectivement à des profondeurs d'enfouissement d'au moins 150m et 400m