146 research outputs found
El mes de recolecciĂłn de la macha (Mesodesma donacium) determinado por sus lĂneas de crecimiento: aplicaciones arqueolĂłgicas
IntroducciĂłn La macha (Mesodesma donacium) tiene una importancia econĂłmica desde que llegaron los primeros pescadores recolectores a la costa peruana hace 11âŻ000 años. Ciertos conchales constituidos casi exclusivamente de las conchas de este bivalvo forman montĂculos de hasta diez metros de alto y atestiguan de una larga e intensa explotaciĂłn pasada (Engel, 1957; Sandweiss et al., 1989; 1998; LavallĂ©e et al., 1999). Los arqueĂłlogos disponen en general de muy pocos Ăndices para determinar si l..
Template Based MDE
National audienceIn MDE, design of systems can be improved and accelerated thanks to reusable models which are made available in model repositories or libraries. This paper focuses on the construction and exploitation of " oâ”-the-shelf " model template bases. Model templates are parameterized models which are adaptable to various application contexts. Due to their parameterization, model templates have their own modeling space. In this paper, we present the main construction and composition operations that underlie this space while presenting its dedicated engineering processes and actors. A software environment is shown to illustrate template based engineering in Eclipse
Une fiscalité compétitive dans un monde concurrentiel.
Ăconomie trĂšs largement ouverte, intĂ©grĂ©e, situĂ©e au centre de lâEurope, la France entre en concurrence directe avec ses voisins aussi bien en termes de marchĂ©s quâen termes dâattractivitĂ©. Il lui est impossible aujourdâhui de rĂ©flĂ©chir Ă son systĂšme fiscal sans prendre en compte son ouverture et la question de sa compĂ©titivitĂ©. Or les performances dĂ©cevantes de la France Ă lâexportation, comparĂ©es notamment Ă celles de lâAllemagne, sâexpliquent davantage par des facteurs internes que par un mauvais positionnement Ă lâexportation. Parce quâelle est lâune des plus lourde dâEurope, la fiscalitĂ© française figure en bonne place parmi les facteurs qui pourraient nuire Ă la compĂ©titivitĂ© de ses entreprises. La radiographie des Ă©changes extĂ©rieurs de la France fait ressortir quelques Ă©lĂ©ments utiles pour comprendre les dĂ©terminants de la compĂ©titivitĂ© française et les enjeux de la concurrence fiscale : âą Bien plus que de se focaliser sur la concurrence exercĂ©e par les pays Ă©mergents, lâessentiel pour le maintien de la compĂ©titivitĂ© est de limiter les diffĂ©rences de coĂ»ts de production vis-Ă -vis de nos voisins directs. âą La clĂ© de notre compĂ©titivitĂ© se trouve dans les produits de haute technologie et dans le haut de gamme. Ces productions nĂ©cessitent une forte intensitĂ© capitalistique et en travail qualifiĂ©. Il est essentiel, pour la compĂ©titivitĂ© des entreprises, de ne pas imposer trop lourdement ces bases fiscales. âą Une amĂ©lioration des performances globales de la France Ă lâexportation impliquerait un accroissement du nombre dâentreprises exportatrices. En cela, les entraves Ă lâinvestissement et la croissance des PME nuisent tout particuliĂšrement Ă la compĂ©titivitĂ©. Ce rapport nâa pas pour objectif de proposer une rĂ©forme fiscale, mais plutĂŽt de montrer comment la thĂ©orie Ă©conomique peut apporter des Ă©lĂ©ments utiles au dĂ©bat. Il suggĂšre que, pour renforcer la compĂ©titivitĂ© et lâattractivitĂ© dâune Ă©conomie, le systĂšme fiscal devrait prĂ©senter les caractĂ©ristiques suivantes : âą une pression fiscale comparable ou infĂ©rieure aux pays proches gĂ©ographiquement ; âą une faible fiscalitĂ© sur le capital physique et sur le travail qualifiĂ©, facteurs mobiles qui sont aussi les Ă©lĂ©ments dĂ©terminants de la compĂ©titivitĂ© ; âą un dispositif ne favorisant pas les stratĂ©gies dâoptimisation fiscale, via en particulier une plus grande neutralitĂ© selon le mode de financement de lâinvestissement. Les auteurs du rapport portent un regard circonspect sur des mesures consistant Ă substituer de la TVA Ă des cotisations sociales : il ne faut pas attendre dâeffets importants de telles mesures sur la compĂ©titivitĂ© ; Ă lâinverse, de telles substitutions peuvent avoir des effets redistributifs sâavĂ©rant dĂ©favorables Ă la compĂ©titivitĂ©. De ce point de vue, lâobjectif dâemploi ne devrait pas ĂȘtre confondu avec lâobjectif de compĂ©titivitĂ©. De mĂȘme, la fiscalitĂ© environnementale, si elle se justifie pleinement au regard des engagements internationaux en matiĂšre de climat, ne saurait se substituer durablement Ă des cotisations sociales jugĂ©es trop lourdes ; Ă lâinverse, les craintes que cette fiscalitĂ© soulĂšve en matiĂšre de compĂ©titivitĂ© sont sans doute exagĂ©rĂ©es. Lâimpression qui se dĂ©gage est alors que la compĂ©titivitĂ© est lâennemie de lâĂ©quitĂ©, puisquâune fiscalitĂ© compĂ©titive se veut lĂ©gĂšre, en particulier sur les facteurs les plus mobiles, et quâelle doit favoriser le financement de biens publics productifs, au dĂ©triment Ă©ventuel des 3 transferts sociaux. Bien sĂ»r, une attrition des activitĂ©s Ă forte valeur ajoutĂ©e en France sonnerait le glas de notre Etat providence, les transferts sociaux et subventions au travail peu qualifiĂ© ne pouvant durablement ĂȘtre financĂ©s par emprunt. A lâinverse, cependant, on perçoit aisĂ©ment les limites dâune politique consistant Ă attirer sur le territoire des activitĂ©s Ă lâaide dâune fiscalitĂ© attrayante. Alors, comment faire coĂŻncider les objectifs de compĂ©titivitĂ© et dâĂ©quitĂ© ? La France aura du mal Ă prĂ©server son modĂšle social sans une plus grande coordination au niveau europĂ©en. Compte tenu des Ă©lĂ©ments prĂ©sentĂ©s dans ce rapport, une coordination fiscale ne nĂ©cessite pas (1) de rĂ©unir tous les Etats membres, et (2) dâharmoniser les taux. Elle pourrait consister simplement Ă sâentendre sur une rĂ©partition de la charge fiscale entre les trois grandes assiettes : consommation, travail et capital â ceci entre pays proches gĂ©ographiquement. Certes, chaque pays individuellement ne peut espĂ©rer taxer effectivement le capital, Ă©tant donnĂ©e la mobilitĂ© de cette assiette. Mais lâUnion europĂ©enne est un grand pays qui sâignore : au niveau de lâunion, le taux de rendement du capital nâest pas dĂ©terminĂ© par le niveau mondial et les Etats membres pourraient dĂ©cider collectivement de rĂ©Ă©quilibrer leur fiscalitĂ©. Les Etats-membres sortiront de la crise Ă©conomique mondiale avec des finances publiques fortement dĂ©gradĂ©es. Peut-ĂȘtre cette situation critique obligera-t-elle les Etats-membres Ă rĂ©aliser ensemble cette coordination qui leur fait dĂ©faut. Lâargument de la souverainetĂ© fiscale jouera alors dans le sens de la coordination : sans coordination, il sera difficile pour les Etats membres de trouver les moyens de dĂ©gonfler leurs dettes publiques. Dans lâimmĂ©diat, la piste dâun Ă©largissement de la base de lâIS, avec rĂ©duction du taux dâimposition, mĂ©riterait dâĂȘtre explorĂ©e. Une telle rĂ©forme permettrait de rĂ©duire les distorsions de financement, de limiter les possibilitĂ©s dâoptimisation et dâattĂ©nuer ainsi lâinĂ©galitĂ© entre petites et grandes entreprises, dans un environnement oĂč le dynamisme des exportations viendra essentiellement des entreprises de taille moyenne.ImpĂŽt; systĂšme fiscal; ouverture; compĂ©titivitĂ©;
Affine Multibanking for High-Level Synthesis
International audienceIn the last decade, FPGAs appeared as a credible alternative for big data and high-performance computing applications. However, programming an FPGA is tedious: given a function to implement, the circuit must be designed from scratch by the developer. In this short paper, we address the compilation of data placement under parallelism and resource constraints. We propose an HLS algorithm able to partition the data across memory banks, so parallel accesses will target distinct banks to avoid data transfer serialization. Our algorithm is able to reduce the number of banks and the maximal bank size. Preliminary evaluation shows promising results
Affine Multibanking for High-Level Synthesis
In the last decade, FPGAs appeared as a credible alternative for big data and high-performance computing applications. However, programming an FPGA is tedious: given a function to implement, the circuit configuration must be built from scratch by the developer. Hence the emergence of high-level circuit compilers (high-level synthesis, HLS), able to translate a C program to an FPGA circuit configuration. Unlike software parallelization, there is no operating system to place the computation and the memory at runtime. All the parallelization decisions must be done at compile time. In this report, we address the compilation of data placement under parallelism and resource constraints. We propose an HLS algorithm able to partition the data across memory banks, so parallel access will target distinct banks to avoid data transfer serialization. Our algorithm is able to minimize the number of banks and the maximal bank size.Dans la derniere decennie, les FPGA sont apparus comme une alternative credible pour le big data et le calcul haute performance. Malheureusement, la programmation des FPGA requiert la conception dâune configuration de circuit, ce qui est hors dâatteinte pour un programmeur. DâoĂč lâĂ©mergence de la synthĂšse de circuit haut-niveau (High-Level Synthesis, HLS), capable de compiler un code C canonique en configuration de circuit FPGA. Contrairement `a la parallĂ©lisation logicielle, toutes les dĂ©cisions de placement des donnĂ©es et des calculs doivent ĂȘtre prises statiquement, Ă la compilation. Dans ce rapport, nous ÌĂ©tudions la compilation dâun placement de donnĂ©es sous contrainte de parallĂ©lisme et de taille. Nous proposons un algorithme de HLS capable de partitionner les donnĂ©es sur des bancs, de sorte que deux donnĂ©es accĂ©dĂ©es en mĂȘme temps soient sur deux bancs diffĂ©rents, et puissent ainsi ĂȘtre accessibles en parallĂšle.Notre algorithme est capable de trouver une partition qui minimise le nombre de bancs et la taille maximale dâun banc
Asymptotics of Selberg-like integrals: The unitary case and Newton's interpolation formula
We investigate the asymptotic behavior of the Selberg-like integral ,
as for different scalings of the parameters and with .
Integrals of this type arise in the random matrix theory of electronic
scattering in chaotic cavities supporting channels in the two attached
leads. Making use of Newton's interpolation formula, we show that an asymptotic
limit exists and we compute it explicitly
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High-resolution marine data and transient simulations support orbital forcing of ENSO amplitude since the mid-Holocene
Lack of constraint on spatial and long-term temporal variability of the El Niño southern Oscillation (ENSO) and its sensitivity to external forcing limit our ability to evaluate climate models and ENSO future projections. Current knowledge of Holocene ENSO variability derived from paleoclimate reconstructions does not separate the role of insolation forcing from internal climate variability. Using an updated synthesis of coral and bivalve monthly resolved records, we build composite records of seasonality and interannual variability in four regions of the tropical Pacific: Eastern Pacific (EP), Central Pacific (CP), Western Pacific (WP) and South West Pacific (SWP). An analysis of the uncertainties due to the sampling of chaotic multidecadal to centennial variability by short records allows for an objective comparison with transient simulations (mid-Holocene to present) performed using four different Earth System models. Sea surface temperature and pseudo-ÎŽ18O are used in model-data comparisons to assess the potential influence of hydroclimate change on records. We confirm the significance of the Holocene ENSO minimum (HEM) 3-6ka compared to low frequency unforced modulation of ENSO, with a reduction of ENSO variance of âŒ50 % in EP and âŒ80 % in CP. The approach suggests that the increasing trend of ENSO since 6ka can be attributed to insolation, while models underestimate ENSO sensitivity to orbital forcing by a factor of 4.7 compared to data, even when accounting for the large multidecadal variability. Precession-induced change in seasonal temperature range is positively linked to ENSO variance in EP and to a lesser extent in other regions, in both models and observations. Our regional approach yields insights into the past spatial expression of ENSO across the tropical Pacific. In the SWP, today under the influence of the South Pacific Convergence Zone (SPCZ), interannual variability was increased by âŒ200 % during the HEM, indicating that SPCZ variability is independent from ENSO on millennial time scales
Controls on gut phosphatisation : the trilobites from the Weeks Formation LagerstÀtte (Cambrian; Utah)
Despite being internal organs, digestive structures are frequently preserved in Cambrian LagerstÀtten. However, the reasons for their fossilisation and their biological implications remain to be thoroughly explored. This is particularly true with arthropods--typically the most diverse fossilised organisms in Cambrian ecosystems--where digestive structures represent an as-yet underexploited alternative to appendage morphology for inferences on their biology. Here we describe the phosphatised digestive structures of three trilobite species from the Cambrian Weeks Formation LagerstÀtte (Utah). Their exquisite, three-dimensional preservation reveals unique details on trilobite internal anatomy, such as the position of the mouth and the absence of a differentiated crop. In addition, the presence of paired pygidial organs of an unknown function is reported for the first time. This exceptional material enables exploration of the relationships between gut phosphatisation and the biology of organisms. Indeed, soft-tissue preservation is unusual in these fossils as it is restricted to the digestive structures, which indicates that the gut played a central role in its own phosphatisation. We hypothesize that the gut provided a microenvironment where special conditions could develop and harboured a source of phosphorus. The fact that gut phosphatization has almost exclusively been observed in arthropods could be explained by their uncommon ability to store ions (including phosphorous) in their digestive tissues. However, in some specimens from the Weeks Formation, the phosphatisation extends to the entire digestive system, suggesting that trilobites might have had some biological particularities not observed in modern arthropods. We speculate that one of them might have been an increased capacity for ion storage in the gut tissues, related to the moulting of their heavily-mineralised carapace
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Large-scale features and evaluation of the PMIP4-CMIP6 midHolocene simulations
The mid-Holocene (6,000 years ago) is a standard experiment for the evaluation of the simulated response of global climate models using paleoclimate reconstructions. The latest mid-Holocene simulations are a contribution by the Palaeoclimate Model Intercomparison Project (PMIP4) to the current phase of the Coupled Model Intercomparison Project (CMIP6). Here we provide an initial analysis and evaluation of the results of the experiment for the mid-Holocene. We show that state-of-the-art models produce climate changes that are broadly consistent with theory and observations, including increased summer warming of the northern hemisphere and associated shifts in tropical rainfall. Many features of the PMIP4-CMIP6 simulations were present in the previous generation (PMIP3-CMIP5) of simulations. The PMIP4-CMIP6 ensemble for the mid-Holocene has a global mean temperature change of -0.3 K, which is -0.2 K cooler that the PMIP3-CMIP5 simulations predominantly as a result of the prescription of realistic greenhouse gas concentrations in PMIP4-CMIP6. Neither this difference nor the improvement in model complexity and resolution seems to improve the realism of the simulations. Biases in the magnitude and the sign of regional responses identified in PMIP3-CMIP5, such as the amplification of the northern African monsoon, precipitation changes over Europe and simulated aridity in mid-Eurasia, are still present in the PMIP4-CMIP6 simulations. Despite these issues, PMIP4-CMIP6 and the mid-Holocene provide an opportunity both for quantitative evaluation and derivation of
emergent constraints on climate sensitivity and feedback strength
The Iso2k database: a global compilation of paleo-ÎŽ18O and ÎŽ2H records to aid understanding of common era climate
Reconstructions of global hydroclimate during the Common Era (CE; the past ~2,000 years) are important for providing context for current and future global environmental change. Stable isotope ratios in water are quantitative indicators of hydroclimate on regional to global scales, and these signals are encoded in a wide range of natural geologic archives. Here we present the Iso2k database, a global compilation of previously published datasets from a variety of natural archives that record the stable oxygen (ÎŽ18O) or hydrogen (ÎŽÂČH) isotopic composition of environmental waters, which reflect hydroclimate changes over the CE. The Iso2k database contains 756 isotope records from the terrestrial and marine realms, including: glacier and ground ice (205); speleothems (68); corals, sclerosponges, and mollusks (145); wood (81); lake sediments and other terrestrial sediments (e.g., loess) (158); and marine sediments (99). Individual datasets have temporal resolutions ranging from sub-annual to centennial, and include chronological data where available. A fundamental feature of the database is its comprehensive metadata, which will assist both experts and non-experts in the interpretation of each record and in data synthesis. Key metadata fields have standardized vocabularies to facilitate comparisons across diverse archives and with climate model simulated fields. This is the first global-scale collection of water isotope proxy records from multiple types of geological and biological archives. It is suitable for evaluating hydroclimate processes through time and space using large-scale synthesis, model-data intercomparison and (paleo)data assimilation. The Iso2k database is available for download at: https://doi.org/10.25921/57j8-vs18 (Konecky and McKay, 2020) and is also accessible via through the NOAA/WDS Paleo Data landing page: https://www.ncdc.noaa.gov/paleo/study/29593
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