Testing the methodological utility of trace element analysis for detetecting dietary differences in fossil fauna from Turkana

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An earlier origin for the Acheulian

The Acheulian is one of the first defined prehistoric technocomplexes and is characterized by shaped bifacial stone tools It probably originated in Africa, spreading to Europe and Asia perhaps as early as 1 million years (Myr) ago. The origin of the Acheulian is thought to have closely coincided with major changes in human brain evolution, allowing for further technological developments. Nonetheless, the emergence of the Acheulian remains unclear because well-dated sites older than 1.4Myr ago are scarce. Here we report on the lithic assemblage and geological context for the Kokiselei 4 archaeological site from the Nachukui formation (West Turkana, Kenya) that bears characteristic early Acheulian tools and pushes the first appearance datum for this stone-age technology back to 1.76Myr ago. Moreover, co-occurrence of Oldowan and Acheulian artefacts at the Kokiselei site complex indicates that the two technologies are notmutually exclusive time-successive components of an evolving cultural lineage, and suggests that the Acheulian was either imported from another location yet to be identified or originated from Oldowan hominins at this vicinity. In either case, the Acheulian did not accompany the first human dispersal from Africa despite being available at the time. This may indicate that multiple groups of hominins distinguished by separate stone-tool-making behaviours and dispersal strategies coexisted in Africa at 1.76Myr ago

Analyse de sensibilité à des changements morphologiques du complexe de l’épaule : application aux gestes de percussion au cours de débitage oldowayen

Si la fabrication et l’utilisation d’outils lithiques ont incontestablement joué un rôle déterminant dans l’évolution des hominines, l’impact de tels comportements sur leur morphologie semble moins faire consensus. Toutefois, il semble que l’architecture et les proportions du complexe de l’épaule chez les premiers représentants du genre Homo aient pu avoir été contraintes par ces comportements. Afin de discuter des potentiels avantages adaptatifs de ces traits morphologiques dans le cadre de ..

A generic and systematic procedure to derive a simplified model from the anaerobic digestion model No. 1 (ADM1)

International audienceThe anaerobic digestion model No.1 (ADM1) developed by the IWA Task Group for mathematical modellingof anaerobic digestion processes Batstone et al. [1] is a structural model which describes the mainbiochemical and physicochemical processes. For such purposes, other models have been proposed todescribe anaerobic processes with a reduced set of parameters, state variables and processes. Amongthem, the anaerobic model No. 2 (AM2) proposed by Bernard et al. [2] which describes the degradationof soluble organic compounds, appears as a model well-suited for control and optimization applications.In this work, we aimed at obtaining a model of reduced dimensions on the basis of which to synthesizeregulators or observers with guarantees of performance, stability and robustness. Specifically, our contributionis twofold. First, a modified version of the AM2 is proposed while preserving the simplicity ofthe new model “AM2HN”. Second, we propose a systematic and generic state association procedure inorder to obtain such a simplified model from any validated ADM1.Simulations and comparisons with the predictions of theADM1for a case study involving the anaerobicdigestion of waste sludge are presented along with satisfactory results

Matières premières lithiques et comportements techno-économiques des homininés plio-pléistocènes du Turkana occidental, Kenya

NANTERRE-BU PARIS10 (920502102) / SudocSudocFranceF

An Earlier Origin for Stone Tool Making: Implications for Cognitive Evolution and the Transition to Homo

International audience"The discovery of the earliest known stone tools at Lomekwi 3 (LOM3) from West Turkana, Kenya, dated to 3.3 Ma, raises new questions about the mode and tempo of key adaptations in the hominin lineage. The LOM3 tools date to before the earliest known fossils attributed to Homo at 2.8 Ma. They were made and deposited in a more C3 environment than were the earliest Oldowan tools at 2.6 Ma. Their discovery leads to renewed investigation on the timing of the emergence of human-like manipulative capabilities in early hominins and implications for reconstructing cognition. The LOM3 artefacts form part of an emerging paradigm shift in palaeoanthropology, in which: tool-use and tool-making behaviours are not limited to the genus Homo; cranial, post-cranial and behavioural diversity in early Homo is much wider than previously thought; and these evolutionary changes may not have been direct adaptations to living in savannah grassland environments.

An interdisciplinary approach to percussive technology - International conference, Institute of Archaeology, University College London, September 18th - 19th, 2014

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Towards a systematic approach to reduce complex bioprocess models - Application to the ADM1

International audienceA mathematical reduction method named Homotopy is applied to the Anaerobic Digestion Model No. 1 or ADM1, cf. (Batstone et al., 2002), a complex model of bioprocess describing the anaerobic digestion. Because we are interested in what happens on small timescales, the proposed method neglects the slow dynamics keeping only the fastest ones in using the technique of eigenvalue-state association. This transformation is described by the Homotopy matrix H. Simulations show that the reduced model behaves globally like the initial model at steady states. This approach is confronted with the reduction method using balancing of empirical gramians, an approach that ensures the same input-output behaviour of the reduced model with regard to the original one

Anaerobic digestion models for control purposes: a short survey

International audienceIn the literature one can find two important types of models: (i) ADM1-like models, mostly dedicated to knowledge integration to come up with a real virtual anaerobic digestion (AD) process and (ii) simplified models of the AD including a limited number of steps, mostly dedicated to process optimization and control. In this paper, we go through these two types of models by presenting first, a state of the art of the ADM1 in terms of applications and modifications and then some examples of simple models of AD. We claim that the interest of complex ADM1-like models can be relevant only if their emergent properties are analyzed. A way to do so is to study simpler models and to infer what their properties imply to the so-called “complex” models