Calibration and improved prediction of computer models by universal Kriging

This paper addresses the use of experimental data for calibrating a computer model and improving its predictions of the underlying physical system. A global statistical approach is proposed in which the bias between the computer model and the physical system is modeled as a realization of a Gaussian process. The application of classical statistical inference to this statistical model yields a rigorous method for calibrating the computer model and for adding to its predictions a statistical correction based on experimental data. This statistical correction can substantially improve the calibrated computer model for predicting the physical system on new experimental conditions. Furthermore, a quantification of the uncertainty of this prediction is provided. Physical expertise on the calibration parameters can also be taken into account in a Bayesian framework. Finally, the method is applied to the thermal-hydraulic code FLICA 4, in a single phase friction model framework. It allows to improve the predictions of the thermal-hydraulic code FLICA 4 significantly

Modulation of the texture of emulsified and acidified model systems by the addition of protein aggregates

Modulation of the texture of emulsified and acidified model systems by the addition of protein aggregates. Colloque Biopolymers 201

Converging toward a common speech code: imitative and perceptuo-motor recalibration processes in speech production

International audienceAuditory and somatosensory systems play a key role in speech motor control. In the act of speaking, segmental speech movements are programmed to reach phonemic sensory goals, which in turn are used to estimate actual sensory feedback in order to further control production. The adult's tendency to automatically imitate a number of acoustic-phonetic characteristics in another speaker's speech however suggests that speech production not only relies on the intended phonemic sensory goals and actual sensory feedback but also on the processing of external speech inputs. These online adaptive changes in speech production, or phonetic convergence effects, are thought to facilitate conversational exchange by contributing to setting a common perceptuo-motor ground between the speaker and the listener. In line with previous studies on phonetic convergence, we here demonstrate, in a non-interactive situation of communication, online unintentional and voluntary imitative changes in relevant acoustic features of acoustic vowel targets (fundamental and first formant frequencies) during speech production and imitation. In addition, perceptuo-motor recalibration processes, or after-effects, occurred not only after vowel production and imitation but also after auditory categorization of the acoustic vowel targets. Altogether, these findings demonstrate adaptive plasticity of phonemic sensory-motor goals and suggest that, apart from sensory-motor knowledge, speech production continuously draws on perceptual learning from the external speech environment

Plasticity of sensory-motor goals in speech production: behavioral evidence from phonetic convergence and speech imitation

International audienceImitation is one of the major processes by which humans develop social interactions. In speech communication, imitative processes are used from birth to adulthood, as highlighted by children’s mimicking abilities and by adult’s tendency to automatically “imitate” a number of acoustic-phonetic characteristics in another speaker’s speech. These adaptive changes are thought to play a key role in speech development/acquisition and to facilitate conversational exchange by contributing to setting a common perceptuo-motor link between speakers. Based on acoustic analyses of speech production in various laboratory tasks, the present study aimed to better characterize sensory-to-motor adaptive processes involved in unintentional as well as voluntary speech imitation, and to test possible motor plastic changes due to auditory-motor recalibration mechanisms

Multiframe Scene Flow with Piecewise Rigid Motion

We introduce a novel multiframe scene flow approach that jointly optimizes the consistency of the patch appearances and their local rigid motions from RGB-D image sequences. In contrast to the competing methods, we take advantage of an oversegmentation of the reference frame and robust optimization techniques. We formulate scene flow recovery as a global non-linear least squares problem which is iteratively solved by a damped Gauss-Newton approach. As a result, we obtain a qualitatively new level of accuracy in RGB-D based scene flow estimation which can potentially run in real-time. Our method can handle challenging cases with rigid, piecewise rigid, articulated and moderate non-rigid motion, and does not rely on prior knowledge about the types of motions and deformations. Extensive experiments on synthetic and real data show that our method outperforms state-of-the-art.Comment: International Conference on 3D Vision (3DV), Qingdao, China, October 201

Présentation

Les pratiques de l’espace qui s’inventent dans les métropoles en mutation de notre monde postcolonial sont indissociables de textes qui en formulent les poétiques. Tel est le parti pris de ce volume, qui réunit des travaux de deux séminaires accueillis au Musée du quai Branly, à Paris, de 2010 à 2014. Marquées par des mouvements démographiques de moins en moins contrôlables, les métamorphoses urbaines les plus imprévisibles à l’échelle du monde portent avec elles de nouveaux espaces souvent ..

Les ADN topoisomérases du crenarchaeon hyperthermophile Sulfolobus solfataricus (régulateurs du métabolisme de l'ADN ?)

Les ADN topoisomérases sont des enzymes capables de moduler la torsion de la double hélice d ADN afin de rendre compatible sa topologie avec les différents processus cellulaires impliquant l ADN. Les hyperthermophiles possèdent au moins une topoisomérase particulière, la reverse gyrase qui est constituée à la fois d un domaine topoisomérase IA etd un domaine hélicase de type SF2. Mon sujet de thèse a eu pour objectif de déterminer principalement l implication des ADN topoisomérases IA dans les différents processus cellulaires de Sulfolobus solfataricus. Ce crenarchaeon hyperthermophile possède, en plus, d une ADN topoisomérase de type II (Topo VI), trois ADN-topoisomérases IA dont une classique (TopA) et deux reverse gyrases (TopR1 et TopR2). Notre approche a permis d estimer, pour la première fois, le nombre de TopR1 et de TopR2 par cellule en fonction des différentes conditions testées. L étude des variations quantitatives des ADN topoisomérases a clairement mis en évidence que TopR1 et TopR2 sont régulées différemment ce qui renforce l hypothèse d une spécialisation de leurs fonctions. Nous avons ainsi montré que TopR1 est responsable du maintien de l homéostasie du surenroulement de l ADN. Si la Topo VI de par son activité antagoniste est impliquée dansce même contrôle homéostatique, elle ne fait pas l objet d une régulation quantitative. De plus, nous avons mis en évidence que TopR1 était liée à la vie à haute température. Enfin, nos résultats suggèrent que TopR2 serait pour sa part impliquée dans la stabilité des génomes. L identification des partenaires protéiques respectifs des quatre ADN topoisomérases de S. solfataricus permettra d avoir une vision globale des réseaux de régulation permettant derésoudre les différentes des contraintes topologiques générées au cours de la vie de cet hyperthermophile.DNA topoisomerases act in all DNA metabolism processes to control the DNA topology. Hyperthermophiles possess at least a particular topoisomerase, the reverse gyrase composed of a DNA topoisomerase IA domain and a helicase SF2 domain within the same polypeptide. The general objective of my thesis was to determine the involvement of each DNA topoisomerase in different cellular processes of S. solfataricus. This hyperthermophilic crenarchaeon possesses in addition to a type II DNA topoisomerase (Topo VI), three DNA topoisomerases IA : a classical one (TopA) and two reverse gyrases (TopR1 and TopR2). Our experimental approach allowed to estimate for the first time the number of TopR1 and TopR2 per cell in relation to different conditions. The study of quantitative variations of each DNA topoisomerase clearly showed that TopR1 and TopR2 are differently regulated suggesting that they are involved in distinct cellular processes. Indeed, we showed that TopR1 is the main actor of the homeostatic control of the DNA supercoiling. If the Topo VI with its antogonistic activity is involved in this homeostatic control, there is no regulation at the level of protein quantity. In addition we evidenced that TopR1 is somehow linked to the life at high temperature. Our results suggest that TopR2 is involved in genome stability. The identification of the respective potential partners of the four DNA topoisomerases of S. solfataricus will allow to get a more detailed understanding of the DNA topology regulation during the hyperthermophilic life style.EVRY-Bib. électronique (912289901) / SudocSudocFranceF

Functional interaction of reverse gyrase with single-strand binding protein of the archaeon Sulfolobus

Reverse gyrase is a unique hyperthermophile-specific DNA topoisomerase that induces positive supercoiling. It is a modular enzyme composed of a topoisomerase IA and a helicase domain, which cooperate in the ATP-dependent positive supercoiling reaction. Although its physiological function has not been determined, it can be hypothesized that, like the topoisomerase–helicase complexes found in every organism, reverse gyrase might participate in different DNA transactions mediated by multiprotein complexes. Here, we show that reverse gyrase activity is stimulated by the single-strand binding protein (SSB) from the archaeon Sulfolobus solfataricus. Using a combination of in vitro assays we analysed each step of the complex reverse gyrase reaction. SSB stimulates all the steps of the reaction: binding to DNA, DNA cleavage, strand passage and ligation. By co-immunoprecipitation of cell extracts we show that reverse gyrase and SSB assemble a complex in the presence of DNA, but do not make stable protein–protein interactions. In addition, SSB stimulates reverse gyrase positive supercoiling activity on DNA templates associated with the chromatin protein Sul7d. Furthermore, SSB enhances binding and cleavage of UV-irradiated substrates by reverse gyrase. The results shown here suggest that these functional interactions may have biological relevance and that the interplay of different DNA binding proteins might modulate reverse gyrase activity in DNA metabolic pathways

Spotlight on the invasion of a carabid beetle on an oceanic island over a 105-year period island

The flightless beetle Merizodus soledadinus, native to the Falkland Islands and southern South America, was introduced to the sub-Antarctic Kerguelen Islands in the early Twentieth Century. Using available literature data, in addition to collecting more than 2000 new survey (presence/absence) records of M. soledadinus over the 1991–2018 period, we confirmed the best estimate of the introduction date of M. soledadinus to the archipelago, and tracked subsequent changes in its abundance and geographical distribution. The range expansion of this flightless insect was initially slow, but has accelerated over the past 2 decades, in parallel with increased local abundance. Human activities may have facilitated further local colonization by M. soledadinus, which is now widespread in the eastern part of the archipelago. This predatory insect is a major threat to the native invertebrate fauna, in particular to the endemic wingless flies Anatalanta aptera and Calycopteryx moseleyi which can be locally eliminated by the beetle. Our distribution data also suggest an accelerating role of climate change in the range expansion of M. soledadinus, with populations now thriving in low altitude habitats. Considering that no control measures, let alone eradication, are practicable, it is essential to limit any further local range expansion of this aggressively invasive insect through human assistance. This study confirms the crucial importance of long term biosurveillance for the detection and monitoring of non-native species and the timely implementation of control measures