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Coordination of cytoplasmic flows on large scales in space and time are at the root of many cellular processes, including growth, migration or division. These flows are driven by organized contractions of the actomyosin cortex. In order to elucidate the basic mechanisms at work in the self-organization of contractile activity, we investigate the dynamic patterns of cortex contraction in true slime mold Physarum polycephalum confined in ring-shaped chambers of controlled geometrical dimensions. We make an exhaustive inventory of the different stable contractile patterns in the absence of migration and growth. We show that the primary frequency of the oscillations is independent of the ring perimeter, while the wavelength scales linearly with it. We discuss the consistence of these results with the existing models, shedding light on the possible feedback mechanisms leading to coordinated contractile activity.

Soft cellular systems, such as foams or biological tissues, exhibit highly complex rheological properties, even in the quasistatic regime, that numerical modeling can help to apprehend. We present a numerical implementation of quasistatic strain within the widely used cellular Potts model (CPM). The accuracy of the method is tested by simulating the quasistatic strain of two-dimensional dry foams, both ordered and disordered. The implementation of quasistatic strain in CPM allows the investigation of sophisticated interplays between stress-strain relationship and structural changes that take place in cellular systems.

International audience; PURPOSE: Immune thrombocytopenic purpura (ITP) and autoimmune hemolytic anemia (AIHA) are associated in the definition of Evans syndrome (ES). The occurrence of neurological involvement in this population is poorly described and suggests an underlying primary immunodeficiency (PID). We aimed to describe the clinical manifestations, evolution, and PID profiles of these patients.METHODS: OBS'CEREVANCE is a French, nationwide prospective cohort that includes children with chronic ITP, AIHA, and ES. Patients with a neurological involvement were described. Centralized radiological and pathological reviews and genetic analyses were performed.RESULTS: On October 2016, eight patients (7/181 ES, 1/371 AIHA, and 0/615 ITP) were identified, all male, with a median age (range) at cytopenia onset of 11.5 years (1.6-15.8). Neurological symptoms appeared with a median delay of 6 years (2.5-18) after cytopenia and were polymorphic: seizures (n = 4), cranial nerve palsy (n = 2), Brown-Sequard syndrome (n = 2), intracranial pressure (n = 2), vertigo (n = 1), and/or sensory neuropathy (n = 1). Magnetic resonance imaging (MRI) showed inflammatory lesions, confirmed by pathology for five patients with macrophagic or lymphoplasmocytic infiltrates. All patients had other relevant immunopathological manifestations: pulmonary nodules (n = 6), lymphoproliferation (n = 4), abnormal immunophenotype (n = 8), and hypogammaglobulinemia (n = 7). Treatment consisted of steroids that improved symptomatology and MRI. Five patients relapsed and three had an asymptomatic radiological progression. A PID was identified in 3/8 patients: 22q11.2 microdeletion (n = 1) and CTLA deficiency (n = 2).CONCLUSION: Neurological involvement is a rare and severe late event in the course of childhood ES, which can reveal an underlying PID. Imaging and pathology examination highlight a causative immune dysregulation that may guide targeted therapeutic strategies.

International audience; We describe the clinical, hematologic and genetic characteristics of a retrospective series of 126 subjects from 64 families with hereditary xerocytosis. Twelve patients from six families carried a KCNN4 mutation, five had the recurrent p.Arg352His mutation and one had a new deletion at the exon 7-intron 7 junction. Forty-nine families carried a PIEZO1 mutation, which was a known recurrent mutation in only one-third of the cases and private sequence variation in others; 12 new probably pathogenic missense mutations were identified. The two dominant features leading to diagnosis were hemolysis that persisted after splenectomy and hyperferritinemia, with an inconstant correlation with liver iron content assessed by magnetic resonance imaging. PIEZO1-hereditary xerocytosis was characterized by compensated hemolysis in most cases, perinatal edema of heterogeneous severity in more than 20% of families and a major risk of post-splenectomy thrombotic events, including a high frequency of portal thrombosis. In KCNN4-related disease, the main symptoms were more severe anemia, hemolysis and iron overload, with no clear sign of red cell dehydration; therefore, this disorder would be better described as a ‘Gardos channelopathy’. These data on the largest series to date indicate that PIEZO1-hereditary xerocytosis and Gardos channelopathy are not the same disease although they share hemolysis, a high rate of iron overload and inefficient splenectomy. They demonstrate the high variability in clinical expression as well as genetic bases of PIEZO1-hereditary xerocytosis. These results will help to improve the diagnosis of hereditary xerocytosis and to provide recommendations on the clinical management in terms of splenectomy, iron overload and pregnancy follow-up.

Purpose Safety and organizational research indicates that fostering resilience in organizations is a promising way for improving safety, albeit concrete means to implement resilience are still lacking, especially in the educational field. The purpose of this paper is to propose four principles for training design derived from past and current studies the authors conduct in high-risk organizations. Design/methodology/approach Training for resilience is considered within an enactive approach of human activity building on its properties of autonomy, structural coupling, self-organization, emergence, sensemaking, and metastability. Findings The article describes four educational design principles aiming at improving individual, collective, and organizational resilience: encourage mimetic experiences; pay attention to attention and concernedness; perturb and turn into an event; support participatory-sensemaking and collective sensemaking. Research limitations/implications The training program the authors propose may be challenging to assess. Besides, the most durable solutions to improve safety through resilience are to be found at the crossroad between organizational design and training/development policies. Future research should determine the implementability criteria which are likely to support the use of the principles the authors propose, and contribute to enrich this educational foundation. Originality/value Education and training are conceived herein as high-order means to improve safety through resilience in high-risk organizations, fostering the capacity of the operators and organization to develop efficiently and in the long run. We provide independent but complementary training principles that cannot be hierarchized, but that can be locally prioritized in organizations.

International audience; The Cellular Potts Model (CPM) is a lattice based modeling technique which is widely used for simulating cellular patterns such as foams or biological tissues. Despite its realism and generality, the standard Monte Carlo algorithm used in the scientific literature to evolve this model preserves connectivity of cells on a limited range of simulation temperature only. We present a new algorithm in which cell fragmentation is forbidden for all simulation temperatures. This allows to significantly enhance realism of the simulated patterns. It also increases the computational efficiency compared with the standard CPM algorithm even at same simulation temperature, thanks to the time spared in not doing unrealistic moves. Moreover, our algorithm restores the detailed balance equation, ensuring that the long-term stage is independent of the chosen acceptance rate and chosen path in the temperature space.

International audience; The purpose of this study was to understand how a single pair of expert individual rowers experienced their crew functioning in natural conditions when asked to practice a joint movement for the first time. To fulfill this objective, we conducted a field study of interpersonal coordination that combined phenomenological and mechanical data from a coxless pair activity, to analyze the dynamics of the (inter)subjective experience compared with the dynamics of the team coordination. Using an enactivist approach to social couplings, these heterogeneous data were combined to explore the salience (and accuracy) of individuals' shared experiences of their joint action. First, we determined how each rower experienced the continuous crew functioning states (e.g., feelings of the boat's glide). Second, the phenomenological data helped us to build several categories of oar strokes (i.e., cycles), experienced by the rowers as either detrimentally or effectively performed strokes. Third, the mechanical signatures that correlated with each phenomenological category were tracked at various level of organization (i.e., individual-, interpersonal-, and boat-levels). The results indicated that (a) the two rowers did not pay attention to their joint action during most of the cycles, (b) some cycles were simultaneously lived as a salient, meaningful experience of either a detrimental (n = 15 cycles) or an effective (n = 18 cycles) joint action, and (c) the mechanical signatures diverged across the delineated phenomenological categories, suggesting that the way in which the cycles were experienced emerged from the variance in some mechanical parameters (i.e., differences in peak force level and mean force). Notably, the mechanical measures that helped to explain differences within the phenomenological categories were found at the interpersonal level of analysis, thus suggesting an intentional inter-personal mode of regulation of their joint action. This result is further challenged and discussed in light of extra-personal regulation processes that might concurrently explain why participants did not make an extensive salient experience of their joint action. We conclude that attempts to combine phenomenological and mechanical data should be pursued to continue the research on how individuals regulate the effectiveness of their joint actions' dynamics.

for the PGRx-ITP Study Group; International audience; This prospective observational cohort study aimed to explore the clinical features of incident immune thrombocytopenia in adults and predictors of outcome, while determining if a family history of autoimmune disorder is a risk factor for immune thrombocytopenia. All adults, 18 years of age or older, recently diagnosed with immune thrombocytopenia were consecutively recruited across 21 hospital centers in France. Data were collected at diagnosis and after 12 months. Predictors of chronicity at 12 months were explored using logistic regression models. The association between family history of autoimmune disorder and the risk of developing immune thrombocytopenia was explored using a conditional logistic regression model after matching each case to 10 controls. One hundred and forty-three patients were included: 63% female, mean age 48 years old (Standard Deviation=19), and 84% presented with bleeding symptoms. Median platelet count was 10×109/L. Initial treatment was required in 82% of patients. After 12 months, only 37% of patients not subject to disease-modifying interventions achieved cure. The sole possible predictor of chronicity at 12 months was a higher platelet count at baseline [Odds Ratio 1.03; 95%CI: 1.00, 1.06]. No association was found between outcome and any of the following features: age, sex, presence of either bleeding symptoms or antinuclear antibodies at diagnosis. Likewise, family history of autoimmune disorder was not associated with incident immune thrombocytopenia. Immune thrombocytopenia in adults has been shown to progress to a chronic form in the majority of patients. A lower platelet count could be indicative of a more favorable outcome.

The present study examined how "meaningful time "is constructed and used during acrobatic performance. To do so, six elite athletes (2 tumblers, 2 trampolinists, 2 acrobatic skiers) performed the same acrobatic move within the context of their respective sports. Their activity was described step-by-step using the data obtained from self- confrontation interviews linked to behaviour analysis based on video recordings. The descriptions, which identified the actions, feelings and thoughts of the athletes in relation to the unfolding time of their performance, were then compared. The results demonstrated that acrobatic performance can be divided into different periods that delineate meaningful time. Differences were observed in how the athletes organized activity (e.g. cognitive, physical) according to the specific sport. The results were interpreted as specific ways to use flight time. Key pointsElite acrobatic athletes' activities organize the unfolding of the performance by progressively informing the performers about the state of the evolving situation.The complexity of the activity involved for such acrobatic performances is reduced by a process of timed and situated organization.Athletes' activity consisted to display different jigs corresponding to a meaningful delineate specious present for efficient performance.

International audience; Aim: We investigated the impact of vibrating acoustic airflow, the high frequency (f ≥ 100 Hz) and the low frequency (f ≤ 45 Hz) sound waves, on the enhancement of intrasinus drug deposition.Methods: 81mKr-gas ventilation study was performed in a plastinated human cast with and without the addition of vibrating acoustic airflow. Similarly, intrasinus drug deposition in a nasal replica using gentamicin as a marker was studied with and without the superposition of different modes of acoustic airflow.Results: Ventilation experiments demonstrate that no sinus ventilation was observed without acoustic airflow although sinus ventilation occurred whatever the modes of acoustic airflow applied. Intrasinus drug deposition experiments showed that the high frequency acoustic airflow led to 4-fold increase in gentamicin deposition into the left maxillary sinus and to 2-fold deposition increase into the right maxillary sinus. Besides, the low frequency acoustic airflow demonstrated a significant increase of 4-fold and 2-fold in the right and left maxillary sinuses respectively.Conclusion: We demonstrated the benefit of different modes of vibrating acoustic airflow for maxillary sinus ventilation and intrasinus drug deposition. The degree of gentamicin deposition varies as a function of frequency of the vibrating acoustic airflow and the geometry of the ostia.

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International audience; Purpose:Improvement of clinical outcome in patients with sinuses disorders involves targeting delivery of nebulized drug into the maxillary sinuses. We investigated the impact of nebulization conditions (with and without 100 Hz acoustic airflow), particle size (9.9 μm, 2.8 μm, 550 nm and 230 nm) and breathing pattern (nasal vs. no nasal breathing) on enhancement of aerosol delivery into the sinuses using a realistic nasal replica developed by our team.Methods:After segmentation of the airways by means of high-resolution computed tomography scans, a well-characterized nasal replica was created using a rapid prototyping technology. A total of 168 intrasinus aerosol depositions were performed with changes of aerosol particle size and breathing patterns under different nebulization conditions using gentamicin as a marker.Results:The results demonstrate that the fraction of aerosol deposited in the maxillary sinuses is enhanced by use of submicrometric aerosols, e.g. 8.155 ± 1.476 mg/L of gentamicin in the left maxillary sinus for the 2.8 μm particles vs. 2.056 ± 0.0474 for the 550 nm particles. Utilization of 100-Hz acoustic airflow nebulization also produced a 2- to 3-fold increase in drug deposition in the maxillary sinuses (e.g. 8.155 ± 1.476 vs. 3.990 ± 1.690 for the 2.8 μm particles).Conclusions:Our study clearly shows that optimum deposition was achieved using submicrometric particles and 100-Hz acoustic airflow nebulization with no nasal breathing. It is hoped that our new respiratory nasal replica will greatly facilitate the development of more effective delivery systems in the future.

The rigidity of a network of elastic beams is closely related to its microstructure. We show both numerically and theoretically that there is a class of isotropic networks, which are stiffer than any other isotropic network of same density. The elastic moduli of these stiffest elastic networks are explicitly given. They constitute upper-bounds, which compete or improve the well-known Hashin–Shtrikman bounds. We provide a convenient set of criteria (necessary and sufficient conditions) to identify these networks and show that their displacement field under uniform loading conditions is affine down to the microscopic scale. Finally, examples of such networks with periodic arrangement are presented, in both two and three dimensions. In particular, we present an optimal and isotropic three-dimensional structure which, to our knowledge, is the first one to be presented as such.

International audience; Purpose: Aerosol inhalation therapy is one of the methods to treat rhinosinusitis. However the topical drug delivery to the posterior nose and paranasal sinuses shows only limited efficiency. A precise sinusal targeting remains a main challenge for aerosol treatment of sinus disorders. This paper proposes a comparative study of the nasal deposition patterns of micron and submicron particles using planar gamma-scintigraphy imaging vs. a new 3-dimensional (3D) imaging approach based on SPECT-CT measurements. Methods: Radiolabelled nebulizations have been performed on a plastinated model of human nasal cast coupled with a respiratory pump. First, the benefits provided by SPECT-CT imaging were compared with 2D gamma-scintigraphy and radioactive quantification of maxillary sinus lavage as reference for the sonic 2.8 μm aerosol sinusal deposition. Then, the impact on nasal deposition of various airborne particle sizes was assessed. Results: The 2D methodology overestimates aerosol deposition in the maxillary sinuses by a factor 9 whereas the 3D methodology is in agreement with the maxillary sinus lavage reference methodology. Then with the SPECT-CT approach we highlighted that the higher particle size was mainly deposited in the central nasal cavity contrary to the submicron aerosol particles (33.8 ± 0.6% of total deposition for the 2.8 μm particles vs. 1 ± 0.3% for the 230 nm particles). Conclusion: Benefits of SPECT/CT for the assessment of radiolabelled aerosol deposition in rhinology are clearly demonstrated. This 3D methodology should be preferentially used for scintigraphic imaging of sinusal deposition in Human.

Bubble monolayers are model systems for experiments and simulations of two-dimensional packing problems of deformable objects. We explore the relation between the distributions of the number of bubble sides (topology) and the bubble areas (geometry) in the low liquid fraction limit. We use a statistical model [M. Durand, Europhys. Lett. 90, 60002 (2010)] which takes into account Plateau laws. We predict the correlation between geometrical disorder (bubble size dispersity) and topological disorder (width of bubble side number distribution) over an extended range of bubble size dispersities. Extensive data sets arising from shuffled foam experiments, surface evolver simulations, and cellular Potts model simulations all collapse surprisingly well and coincide with the model predictions, even at extremely high size dispersity. At moderate size dispersity, we recover our earlier approximate predictions [M. Durand, J. Kafer, C. Quilliet, S. Cox, S. A. Talebi, and F. Graner, Phys. Rev. Lett. 107, 168304 (2011)]. At extremely low dispersity, when approaching the perfectly regular honeycomb pattern, we study how both geometrical and topological disorders vanish. We identify a crystallization mechanism and explore it quantitatively in the case of bidisperse foams. Due to the deformability of the bubbles, foams can crystallize over a larger range of size dispersities than hard disks. The model predicts that the crystallization transition occurs when the ratio of largest to smallest bubble radii is 1.4.

International audience; Ventifacts (wind-worn stones) are typical of terrestrial environments remained very long without any vegetation, under hot or cold climates. Therefore, within the sedimentary record, they can allow recognizing desert conditions, even where no aeolian dune deposits are preserved. There seems that, in the recent literature, pebbles and cobbles from various palaeoenvironments were mistaken for ventifacts. This may partly be explained by the scatter and relative scarcity of illustrations to which refer. The aim of this paper is to help recognizing ventifacts in the sedimentary record, based on a critical review of the diagnostic properties generally used, and on new studies permitting to suggest additional criteria. After an evaluation of the sedimentary contexts favourable to preserving ventifacts, the distinctive characters that could be seen on each one are treated in order of increasing alteration of the original appearance: surface features, medium-scale features (new types of pit especially), and general shape. Finally, the problem of distinguishing between ventifacts and aquafacts is approached.

International audience; New insights on the output of a commercial Technegas generator were proposed in order to optimize the generation of a radioactive nanosized aerosol for human inhalation studies. Parameters influencing Technegas generated aerosols (i.e. gaseous atmosphere, generation temperature and storage duration) were analyzed by a combination of size-fractionation and gamma-scintigraphy detection to determine the aerosol aerodynamic-related distributions. It was found that the total radioactivity per mass and number concentrations of aerosols was mostly influenced by the burn temperature, while the radiolabelling of particles was mostly driven by their surface area. 99mTc labeled nanosized carbonaceous primary particles appear mainly to result from nucleation/condensation of the supersaturated vapor during the burning step, and then coalesce into larger particles due to coagulation processes during the residence time in the expansion chamber. We showed that the burn temperature and the aerosol residence time were the main parameters influencing the particle size distribution. Under optimized operating conditions, the amount of radiolabelled nanoparticles substantially increased since the radioactivity median aerodynamic diameter was reduced by half (250 nm--GSD of 2.5) compared with the standard operating conditions of the Technegas generator (450 nm--GSD of 3.4).

Laurent Chiche,1 Alessandra Brescianini,1 Julien Mancini,2 Hervé Servy,3 Jean-Marc Durand11Service de Médecine Interne, Centre de Compétence pour la prise en charge des Cytopénies Auto-immunes, Hôpital de la Conception, Marseille, 2Service de Santé Publique, Hôpital de la Timone, Marseille, 3Association AIMSU, Maison des Associations, La Ciotat, FranceBackground: Patients with rare diseases often lack information about the disease itself and appropriate health care, leading to poor quality of life. Personal health records provide health information which can then be shared between multiple health care providers. Personal health records may also offer a tool for capturing patients' reported outcomes, thus enhancing their empowerment and improving communication with health care professionals. We conducted a pilot study to evaluate the usability of Sanoia, a freely accessible personal health record, which was customized for patients with the rare disease, idiopathic thrombocytopenic purpura (ITP).Methods: The Sanoia interface was expanded with ITP-specific tools. A prospective study was conducted at the referent center to evaluate the usability of this new interface (referred to here as the “tool”) by patients. Forty-three patients were randomized into groups to use or to not use the tool. Its use was evaluated by a specific questionnaire and by surveying individual patient adherence profiles. Evaluation of health-related quality of life using the ITP patient assessment questionnaire, was performed at baseline and after 1, 3, and 6 months via postal mail.Results: The groups were similar at inclusion in terms of characteristics, including global quality of life. During the study period, the tool was used to update the personal records of 19/28 patients (68%), with a median of two connections to the tool (range 1–12) plus access by various health care professionals (n = 22). In addition, 15/19 (78%) patients used the "personal notes" section at least once. We observed no significant changes in quality of life between patients with or without the tool during the study period.Conclusion: This pilot study demonstrates the good usability of the new customized Sanoia interface for patients with ITP. Additional studies will increase its usability further, and its interface could be adapted for use with other rare chronic diseases.Keywords: electronic personal health records, rare diseases, idiopathic thrombocytopenic purpura

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International audience; Aim: Intranasal aerosol administration of drugs is widely used by ENT specialists. Although clinical evidence is still lacking, intranasal nebulization appears to be an interesting therapeutic option for local drug delivery, targeting anatomic sites beyond the nasal valve. The sonic nebulizer NL11SN associates a 100 Hertz (Hz) sound to the aerosolization to improve deposition in the nasal/paranasal sinuses. The aim of the present study was: to evaluate in vivo the influence of associating a 100 Hz sound on sinus ventilation and nasal and pulmonary aerosol deposition in normal volunteers, and; to quantify in vitro aerosol deposition in the maxillary sinuses in a plastinated head model. Material and methods: Scintigraphic analysis of 81mKr gas ventilation and of sonic aerosol (99mTc-DTPA) deposition using the NL11SN was performed in vivo in seven healthy volunteers. In parallel, NL11SN gentamicin nebulization was performed, with or without associated 100 Hz sound, in a plastinated human head model; the gross amount of gentamicin delivered to the paranasal sinuses was determined by fluorescence polarization immunoassay. Results: Associating the 100 Hz sound to 81mKr gas ensured paranasal sinus ventilation in healthy volunteers. 99mTc-DTPA particles nebulized with the NL11SN were deposited predominantly in the nasal cavities (2/3, vs 1/3 in the lungs). In vitro, the use of NL11SN in sonic mode increased gentamicin deposition threefold in the plastinated model sinuses (P < 0.002); the resulting antibiotic deposit would be sufficient to induce a local therapeutic effect. Conclusion: The NL11SN nebulizer ensured preferential nasal cavity aerosol deposition and successfully targeted the maxillary sinuses.

The main aim of this paper is to review Middle Permian through Middle Triassic continental successions in European. Secondly, areas of Middle–Late Permian sedimentation, the Permian–Triassic Boundary (PTB) and the onset of Triassic sedimentation at the scale of the westernmost peri-Tethyan domain are defined in order to construct palaeogeographic maps of the area and to discuss the impact of tectonics, climate and sediment supply on the preservation of continental sediment. At the scale of the western European peri-Tethyan basins, the Upper Permian is characterised by a general progradational pattern from playa-lake or floodplain to fluvial environments. In the northern Variscan Belt domain, areas of sedimentation were either isolated or connected to the large basin, which was occupied by the Zechstein Sea. In the southern Variscan Belt, during the Late Permian, either isolated endoreic basins occurred, with palaeocurrent directions indicating local sources, or basins underwent erosion and/or there was no deposition. These basins were not connected with the Tethys Ocean, which could be explained by a high border formed by Corsica–Sardinia palaeorelief and even parts of the Kabilia microplate. The palaeoflora and sedimentary environments suggest warm and semi-arid climatic conditions. At the scale of the whole study area, an unconformity (more or less angular) is observed almost everywhere between deposits of the Upper Permian and Triassic, except in the central part of the Germanic Basin. The sedimentation gap is more developed in the southern area where, in some basins,Upper Permian sediment does not occur. The large sedimentary supply, erosion and/or lack of deposition during the Late Permian, as well as the variable palaeocurrent direction pattern between theMiddle–Late Permian and the Early Triassic indicate a period of relief rejuvenation during the Late Permian. During the Induan, all the intra-belt basins were under erosion and sediment was only preserved in the extra-belt domains (the northern and extreme southern domains). In the northern domain (the central part of the Germanic Basin), sediment was preserved under the same climatic conditions as during the latest Permian, whereas in the extreme southern domain, it was probably preserved in the Tethys Ocean, implying a large amount of detrital components entering themarinewaters. Mesozoic sedimentation began in the early Olenekian; the ephemeral fluvial systems indicate arid climatic conditions during this period. Three distinct areas of sedimentation occur: a northern and southern domain, separated by an intra-belt domain. The latter accumulated sediments during the Early–Middle Permian and experienced erosion and/or no-deposition conditions between the Middle–Late Permian and the beginning of Mesozoic sedimentation, dated as Anisian to Hettangian. At the top of the Lower Triassic, another tectonically induced, more or less angular unconformity is observed: the Hardegsen unconformity, which is dated as intra-Spathian and is especially found in the North European basins. This tectonic activity created new source areas and a new fluvial style, with marine influences at the distal part of the systems. During the Anisian and Ladinian, continental sedimentation was characterised by a retrogradational trend. In other words, the fluvial system evolved into fluvio-marine environments, attesting to a direct influence of the Tethys Ocean in the southern and northern domains. Both at the end of the Olenekian (Spathian) and during the Anisian, the presence of palaeosols, micro- andmacrofloras indicate less arid conditions throughout this domain

International audience; Plant fossils are rarely preserved within the Upper Permian of western Europe as the majority of continental deposits consists of siliciclastic redbeds. Because organic matter such as plant debris and palynomorphs is destroyed by oxidizing conditions, these red sedimentary facies were often considered as "devoid of life". This paper presents new palaeobotanical data from the Upper Permian strata of Minorca (Balearic Islands, Spain). In addition, a rich and diverse "Thuringian" palynoflora was recovered from the Permian sediments, and several megafloral taxa are recorded. Additionally, a detailed sedimentological analysis of the studied section is provided. The Permian succession shows a general evolution from a ponded floodplain environment to sand-sheet rivers flowing across a semi-arid alluvial plain. Additionally, new palaeobotanical elements, added to the study of palaeosols, allow reconstruction of Late Permian plant growth within the terrestrial environment, as well as a palaeoenvironment reconstruction of the preserved sedimentary interval. At the transition between ponds and alluvial plain deposits, root systems surprisingly similar to those known in extant mangroves are described for the first time within Permian deposits. As there are no other palaeobotanical remains preserved in association, the type of plant that inhabited this environment remains conjectural.

International audience; Description of sedimentary sections and interpretations of sequence stratigraphic evolution of Permian­Triassic red beds of Minorca, allow a new proposal of palaeoenvironment reconstructions. The Permian sediments mainly correspond to floodplain and pond deposits with sheetflood sand-bed rivers (environment DE 1), within a warm and semi-arid climate, and the preserved succession forms one complete stratigraphic cycle. The retrogradational phase of this cycle is represented by alluvial/colluvial deposits grading upwards to environment DE 1 and to extensive floodplain and pond deposits. The progradational phase is characterized by increasing fluvial influence (with palaeocurrent mainly oriented to the SW), palaeosol horizons, and preservation of a Late Permian palynoflora. The uppermost part of this succession is truncated by a major erosional surface. The sediments above this unconformity are characterized by braided river deposits (environment DE 2) with palaeocurrent oriented to the SSW within the more basal conglomeratic facies and to the WNW in overlying units. The absence of extensive floodplain deposits, a paucity of evidence for biogenic activity and palaeosols, together with the presence of ventifacts indicate an arid climatic setting for the succession. This environment evolved from braided rivers (palaeocurrents mainly oriented to the SE, environment DE 3) with in situ palaeosols and reworked breccias to fluvial­coastal and shallow marine deposits (environment DE 4) dated as upper Anisian to Ladinian. This succession characterizes a retrogradational trend. Although the transition between DE 2 and DE 3 was not observed, a switch in palaeocurrent directions may indicate a change in source area. A comparison at a regional scale with other Peri-Tethyan basins allows the succession to be placed within a broader palaeoenvironmental and stratigraphic context during Late Permian to Middle Triassic. During the Late Permian, sedimentation occurred in alluvial, playa-lake or ponded environments where fluvial systems generally flowed southward, except in south-eastern France (oriented to the NE). Within these SW European basins, such as Minorca, the Late Permian succession shows a major retrogradational (evolution from fluvial or alluvial fan deposits to extensive lake, playa or floodplain deposits) and a progradational trend (fluvial or alluvial fan deposits). The Permian­Triassic transition corresponds to an unconformity overlain by braided river deposits with arid climate indicators (aeolian deposits: ventifacts and aeolian dune sedimentation). At the scale of western Europe, this arid episode is dated as Smithian and the Induan age sedimentation deposits seem to be preserved only in the central part of the Germanic Basin. As with all other Peri-Tethyan basins, environment DE 2 of Minorca (above the major erosional surface) is attributed to the Smithian. In the upper part of the studied succession, braided river deposits indicative of less arid climatic conditions are preserved. This succession contains the earliest Mesozoic palaeosols, dated as Anisian by palynomorphs, and expresses a vertical evolution from fluvial to open marine depositional environments attributed to the Muschelkalk transgression.

Networks of elastic beams can deform either by stretching or bending of their members. The primary mode of deformation (bending or stretching) crucially depends on the specific details of the network architecture. In order to shed light on the relationship between microscopic geometry and macroscopic mechanics, we characterize the structural features of networks which deform uniformly, through the stretching of the beams only. We provide a convenient set of geometrical criteria to identify such networks, and derive the values of their effective elastic moduli. The analysis of these criteria elucidates the variability of mechanical response of elastic networks. In particular, our study rationalizes the difference in mechanical behavior of cellular and fiber networks., v2 version of arXiv:0805.4712 was misplaced, as it correponds to a different work and different publication from v1 and v3 versions. This new submission correponds to the work originally published in arXiv:0805.4712v2

Summary Based on the course-of-action theory, this study performed a situated analysis of three elite aerial freestyle skiers’ activity. Data were collected by observation, videotaping and self-confrontation interviews retrospectively build the athletes’ activity. The analysis identified units of action, thought, and feelings and described their relationships during each leap. Comparisons of the different courses of action revealed six components of freestyle skiers’ activity: (1) pick up speed in the descent, (2) manage the curve of the tremplin, (3) take-off, (4) manage the exit of the tremplin, (5) perform rotations, and (6) organize the landing. This study revealed the dynamic and situated property of acrobatic activity. As the leap unfolded, the athletes step-by-step enhanced their knowledge of what was occurring and what they would have to do to perform their best and land on their feet. Points of convergence and divergence with other acrobatic performances are discussed.

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International audience; The aims of this study were to identify and analyse elite athletes' problems in competition. A situated cognition approach placed the emphasis on athletes' actions (i.e. cognitions and behaviours), which were considered to emerge from couplings with selected elements of the context. Fifty-two exercises performed by 10 elite trampolinists were analysed. Field observations, structured interviews, and self-confrontation interviews were conducted and transcribed, and used together with behavioural descriptions derived from video recordings. Performance problems were selected from these reports and from the major infringements of trampoline rules. Qualitative analysis identified the meaningful units of action and their semiotic components for each problem. Four categories of problem were identified and noted to appear either separately or jointly while performing: (a) finding the best moment to begin the performance; (b) finding and maintaining the best mode of involvement to end the performance; (c) recovering normal sensory-motor capacity to perform; and (d) solving problems quickly and definitively while performing. The results suggest that the study of action – situation couplings in sports, as well as of their constantly evolving dynamics, not only reveals elite athletes' psychological activity, but is vital to a deeper understanding of these couplings.

The elementary topological $T1$ process in a two-dimensional foam corresponds to the flip of one film with respect to the geometrical constraints, and is a process by which the structure of an out-of-equilibrium foam evolves. We study both experimentally and theoretically the $T1$ dynamics in a dry two-dimensional foam. The dynamics is controlled by the surface viscoelastic properties of the films (surface shear plus dilatational viscosity, ${\ensuremath{\mu}}_{s}+\ensuremath{\kappa}$, and Gibbs elasticity $ϵ$), and is independent of the shear viscosity of the bulk liquid. Moreover, the dynamics of the $T1$ process provides a tool for measuring the surface rheological properties: we obtained $ϵ=32\ifmmode\pm\else\textpm\fi{}8\text{ }\text{ }\mathrm{mN}/\mathrm{m}$ and ${\ensuremath{\mu}}_{s}+\ensuremath{\kappa}=1.3\ifmmode\pm\else\textpm\fi{}0.7\text{ }\text{ }\mathrm{mPa}\ifmmode\cdot\else\textperiodcentered\fi{}\mathrm{m}\ifmmode\cdot\else\textperiodcentered\fi{}\mathrm{s}$ for sodium dodecyl sulfate, and $ϵ=65\ifmmode\pm\else\textpm\fi{}12\text{ }\text{ }\mathrm{mN}/\mathrm{m}$ and ${\ensuremath{\mu}}_{s}+\ensuremath{\kappa}=31\ifmmode\pm\else\textpm\fi{}12\text{ }\text{ }\mathrm{mPa}\ifmmode\cdot\else\textperiodcentered\fi{}\mathrm{m}\ifmmode\cdot\else\textperiodcentered\fi{}\mathrm{s}$ for bovine serum albumin, in good agreement with literature values.

International audience; New surgical techniques require fine control from the surgeon's point of view. Until recently, the necessary experience was only obtainable through traditional training protocols (using cadavers, animals, etc.). However, numerous training simulators have now been developed for use in this area. We present a new approach based on a three-dimensional finite element software and on different kinds of linear and nonlinear elastic constitutive equations that is able to predict realistic results. To classify these equations in terms of accuracy, we performed ex-vivo experimental measurements on lamb kidneys. The software has been applied to soft tissue deformation, namely lamb kidney and human uterus, and the numerical results have been compared to experimental ones.

International audience; The aim of this paper is to analyse the fluvial evolution of the Lower Triassic in the western part of the Germanic Basin through time and space, as well as the impact of the geodynamic and climatic setting on the preservation of fluvial deposits. The Lower Triassic crops out only in the Vosges Massif and the Black Forest, so well-log studies are required to realise sequence stratigraphy correlations and establish comparisons with others parts of the Germanic Basin. In a first step, we use well-log data analyses to characterise the electrofacies associations in the Triassic and then define the well-log signatures of each formation. In a second step, the characterisation and recognition of genetic sequences and their stacking pattern allow us to define seven minor cycles integrated into two major cycles. Finally, the quantification of the lithologies at different stages of basin evolution leads to the reconstruction of paleoenvironmental maps to illustrate facies evolution through space and time. A comparison with cycles defined in the Germanic Basin allows us to propose correlations of the Lower Triassic on either side of the Rhine Graben and leads to a discussion of the evolution of fluvial systems through time and space. During the Scythian, the fluvial style is characterised by braided fluvial systems evolving laterally into lake deposits towards the central part of the Germanic Basin. During this stage, the basin was a huge depression with very few marine connections in its extreme eastern part. The stratigraphic cycles represent rhythmic fluctuations in relative lake level that could be attributed to sediment supply and/or lake level variations in an arid setting. Four minor stratigraphic cycles are observed that are integrated within a single major stratigraphic cycle. During the period of the stratigraphic base-level rise of the major cycle, a maximum of 233 m of sediment would represent a duration of sedimentation in the Paris Basin of at least 1.8 m.y. During the period of the stratigraphic base-level fall of the major cycle, a maximum of 65 m of sediment would have accumulated over 2.5 m.y. On the western edge of the Germanic Basin, the top of the Scythian is marked by a major sedimentary break characterised by a planation surface, with preservation of the first paleosols, followed by the Hardegsen unconformity. This unconformity is tectonically deformed, leading to the development of a new sedimentation area in the west of the basin. The fluvial sedimentation above this discontinuity shows a trend towards enhanced development of floodplain or lacustrine-type environments at its western margin, with the formation of paleosols. The fluvial systems are linked with sabkhas, and then with a shallow sea connected to the Tethys Ocean. In this context, the stratigraphic cycles are caused by variations in relative sea level and/or sediment supply. The fluvial deposits are preserved in an exoreic basin.

International audience; This article describes the formation of the principal French high-purity silica placer (source for electrometallurgy of silicon and ferrosilicon), the Boudeau deposit in Dordogne, and of one of its subordinate deposits, the Pays Brûlé deposit. Boudeau has always been considered to be a colluvial deposit, formed in a trap produced by extensional tectonism. The present work suggests a new genetic interpretation, based on a combined study of the deposits and their underlying rocks. It shows that the quartz gravel deposits, laid down by stream flow within braided channels, were reworked by karstic progressive sinking, and that the mechanism responsible for the increase in the thickness of the economic formations is cryptokarstic corrosion. This undercovers weathering process, which involves dissolution of karstifiable rocks (oolitic and bioclastic limestones) at their interface with a permeable, non-karstifiable cover composed of chemically pure quartz gravels in a sandy-argillaceous matrix. A typological study of the gravels provides a basis for tackling the problem of their origin and their purity. They seem to be derived mainly from the synmetamorphic quartz mobilisates of the stripped metamorphic units (the lower and upper gneiss units forming the western edge of the Massif Central). Lastly, a dynamic model is suggested for the genesis of the high-purity silica deposits of Dordogne.

21 pages; In order to take into account the studies of the European and American (USA) collections carried out by one of the authors, and of the recent nomenclatural revisions from new footprint discoveries, which have occurred during the last decade, the authors present a critical review of the French Permian palichnofauna. The distribution of the ichnospecies in the stratigraphy of the Lodève Basin, taken as a reference, is outlined. The ichno-associations are then compared with those of other French (Provence), European (Italy, Germany) and USA basins. Based on the ages of different ichnofossiliferous formations, three successive ichnofaunal units can be distinguished in the Permian of Europe. The first developed in the Cisuralian (Asselian to Kungurian). The second is found in the south of France in Kazanian to Lower Tatarian strata, equivalent to the Roadian–Wordian. The third and youngest, dated as Lopingian, is only found in Italy, in the Bolzano Basin. Because of sedimentary gaps, limited observations, sometimes erroneous determinations, and ichnospecies with great vertical distribution, it currently appears that footprints have a low utility for biochronological resolution. Nevertheless, they allow us to discriminate three time intervals in the Permian, as is also the case for skeletal remains.

International audience

International audience; The course-of-action theory (J. Theureau, Le Cours d'action: Analyse Sémiologique, 1992) provided the framework for this study, which described how expert table tennis players' mobilized knowledge in relation with their mode of involvement (exploratory and executory). Matches were videotaped during international meets and the verbalizations of the players as they viewed the tapes were collected a posteriori. The data were processed by transcribing the players' actions and verbalizations, decomposing their activity into elementary units of meaning, labeling the constituents of these units, identifying typical exploratory and executory sequences. The results showed that the knowledge mobilized by the players during the matches differed with their mode of involvement. Knowledge was continuously put into relationship with significant elements in the unfolding situation in order to create interpretive chains, and this contributed to building a meaningful world for the players. The players' cognitive activity was thus revealed to be a permanent construction of meaning aimed at reducing uncertainty in situations of competitive interaction.; Le but de cette étude était de décrire la manière dont les pongistes mobilisaient des connaissances, en relation avec leurs modes d'engagement (exploratoire et exécutoire), au cours de matchs internationaux. L'étude a été menée en référence au cadre théorique du cours d'action (J. Theureau, Le Cours d'action: Analyse Sémiologique, 1992). Les matchs ont été filmés, et les verbalisations des pongistes confrontés à ces enregistrements ont été recueillies a posteriori. Le traitement des données a consisté à retranscrire les actions des pongistes au cours des matchs et leurs verbalisations provoquées lors des entretiens, identifier les unités significatives élémentaires de chaque cours d'action et leurs composantes sous-jacentes, et identifier les séquences types exploratoires et exécutoires. Les résultats montrent que les connaissances mobilisées par les pongistes lors des matchs différaient selon leur mode d'engagement. La mise en relation de ces connaissances avec les éléments significatifs dans la situation actuelle permettait la création de chaînes interprétatives et contribuait à la construction d'un monde pertinent et significatif pour les pongistes. L'activité cognitive des pongistes consiste ainsi comme une construction permanente de significations visant à réduire l'incertitude de la situation d'interaction compétitive.

International audience; Computer simulations of minimal invasive procedures have been developed for surgery planning or training or for the evaluation of surgical procedure. In order to perform realistic and precise simulations of surgery on soft tissue, one key step consists in introducing accurate tissue-specific mechanical parameters. The goal of this work was to transfer an indentation procedure from the laboratory to the operating room using a new portable indentation device. The numerical simulations with 3D finite element software of the experiments allowed us to identify the characteristic rheological properties which minimize the gap between computed end measured physical quantities. The next step will be to extend this procedure to pathologic uterus and to other solid organs.

Many situations in physics, biology, and engineering consist of the transport of some physical quantity through a network of narrow channels. The ability of a network to transport such a quantity in every direction can be described by the average conductivity associated with it. When the flow through each channel is conserved and derives from a potential function, we show that there exists an upper bound of the average conductivity and explicitly give the expression for this upper bound as a function of the channel permeability and channel length distributions. Moreover, we express the necessary and sufficient conditions on the network structure to maximize the average conductivity. These conditions are found to be independent of the connectivity of the vertices.

International audience; This paper both presents a framework for analyzing situated emotions and describes the evolution of two teachers' emotions during their first classroom experiences. Based on Peirce's three categories of experience (1931-1935), we categorized teachers' emotions into affective states, sentiments and emotions-types. The principal results show (a) the emotional flow during ordinary teaching situations, (b) the emergence of contradictory emotions related to phenomena of emotional hysteresis between the affective states and sentiments, (c) the typical character of their emotions related to dependence on the lesson plan and the need to maintain student activity, and (d) the importance of typicalization of emotions in learning to teach.

International audience; Two studies investigated the links between goal orientations and conceptions of sport ability. In Study 1, 194 English children (aged 11-12 yrs) completed a psychological inventory which included questions on achievement goal choice and perceptions of the nature of sport ability. In Study 2, 304 French children (aged 11-17 yrs) completed questionnaires, including the French version of the Perception of Success Questionnaire and the Conception of the Nature of Athletic Ability Questionnaire. Clear relationships were observed between a social comparison goal and a conception of athletic ability as a "gift" and being "general," and between a task mastery goal and the conception of athletic ability as being incremental and determined by learning. The measuring of the causal links that unite goals and ability conceptions, as well as the likely impact of such conceptions on motivation were developed and discussed.