Contrôle de l'équilibre des humains virtuels

Ce chapitre aborde le problème de l'analyse de l'équilibre et de la synthèse par la ommande de la coordination des mouvements d'humains virtuels pour la simulation réaliste d'activités physiques quotidiennes ou professionnelles. nous discutons dans un premier temps les notions d'équilibre postural et de stabilité de cet équilibre dans le cadre particulier des mannequins numériques. Nous introduisons un modèle mécanique pour des mannequins en interaction physique avec l'environnement. À partir d'une formulation générale du problème de l'équilibre, nous examinons un certain nombre de moyens proposés pour caractériser et quantifier la stabilité de l'équilibre des systèmes mécaniques contraints. Nous introduisons la notion de perturbation admissible pour la dynamique posturale vis-à-vis des contraintes de persistance et de non-glissement des appuis. Enfin, nous proposons des techniques de synthèse par la commande de fonctions motrices pour une coordination de l'ensemble du système postural et de manipulation satisfaisant explicitement les contraintes d'équilibre des appuis

Loi relative aux libertés et responsabilités des universités (loi LRU), élection du président et conseil d'administration: une analyse en termes de pouvoir

L'objet de cet article est de mesurer le pouvoir des membres des conseils d'administration des universités françaises tel qu'il est défini par la loi relative aux libertés et responsabilités des universités (loi LRU). A l'aide d'outils issus de la théorie des jeux coopératifs, et en particulier l'indice de pouvoir de Banzhaf, nous montrons que le nombre de représentants d'un groupe, par exemple les professeurs des universités ou les étudiants, et le pouvoir, sont des notions dont les relations sont parfois surprenantes. Nous présentons des exemples où le réel pouvoir de décision n'appartient pas forcément aux groupes auxquels nous pensions intuitivement.conseil d'administration, indice de Banzhaf, pouvoir, universités françaises

Tomato EF-Tsmt, a functional mitochondrial translation elongation factor from higher plants

Ethylene-induced ripening in tomato (Lycopersicon esculentum) resulted in the accumulation of a transcript designated LeEF-Tsmt that encodes a protein with significant homology to bacterial Ts translational elongation factor (EF-Ts). Transient expression in tobacco and sunflower protoplasts of full-length and truncated LeEF-Tsmt- GFP fusion constructs and confocal microscopy observations clearly demonstrated the targeting of LeEF-Tsmt to mitochondria and not to chloroplasts and the requirement for a signal peptide for the proper sorting of the protein. Escherichia coli recombinant LeEF-Tsmt co-eluted from Ni-NTA resins with a protein corresponding to the molecular weight of the elongation factor EF-Tu of E. coli, indicating an interaction with bacterial EF-Tu. Increasing the GDP concentration in the extraction buffer reduced the amount of EF-Tu in the purified LeEF-Tsmt fraction. The purified LeEF-Tsmt stimulated the poly(U)-directed polymerization of phenylalanine 10-fold in the presence of EF-Tu. Furthermore, LeEF-Tsmt was capable of catalysing the nucleotide exchange reaction with E. coli EF-Tu. Altogether, these data demonstrate that LeEF-Tsmt encodes a functional mitochondrial EF-Ts. LeEFTsmt represents the first mitochondrial elongation factor to be isolated and functionally characterized in higher plants

Observation of geometric parametric instability induced by the periodic spatial self-imaging of multimode waves

Spatio-temporal mode coupling in highly multimode physical systems permits new routes for exploring complex instabilities and forming coherent wave structures. We present here the first experimental demonstration of multiple geometric parametric instability sidebands, generated in the frequency domain through resonant space-time coupling, owing to the natural periodic spatial self-imaging of a multimode quasi-continuous-wave beam in a standard graded-index multimode fiber. The input beam was launched in the fiber by means of an amplified microchip laser emitting sub-nanosecond pulses at 1064 nm. The experimentally observed frequency spacing among sidebands agrees well with analytical predictions and numerical simulations. The first order peaks are located at the considerably large detuning of 123.5 THz from the pump. These results open the remarkable possibility to convert a near-infrared laser directly into a broad spectral range spanning visible and infrared wavelengths, by means of a single resonant parametric nonlinear effect occurring in the normal dispersion regime. As a further evidence of our strong space-time coupling regime, we observed the striking effect that all of the different sideband peaks were carried by a well-defined and stable bell-shaped spatial profile.Comment: 5 pages, 4 figure

Sl-ERF2, a Tomato Ethylene Response Factor Involved in Ethylene Response and Seed Germination

Ethylene response factors (ERFs) are plant transcriptional regulators mediating ethylene-dependent gene expression via binding to the GCC motif found in the promoter region of ethylene-regulated genes. We report here on the structural and functional characterization of the tomato Sl-ERF2 gene that belongs to a distinct class of the large ERF gene family. Both spliced and unspliced versions of Sl-ERF2 transcripts were amplified from RNA samples and the search in the public tomato expressed sequence tag (EST) database confirmed the existence of the two transcript species in a number of cDNA libraries. The unspliced transcript contains two open reading frames yielding two hypothetical proteins, a small highly truncated version lacking the APETALA2 domain and a bigger protein lacking the N-terminal MCGGAAII/L consensus peptide specific to ERF members from subfamily IV. Nevertheless, functional Sl-ERF2 protein may only derive from spliced transcripts since, depending on the tissue, the level of the spliced transcript is much higher than that of the unspliced transcript. Sl-ERF2 is expressed in all plant tissues tested, though its transcript accumulates preferentially in germinating seeds and ripening fruit. Overexpression of the Sl-ERF2 gene in transgenic tomato lines results in premature seed germination and enhanced hook formation of darkgrown seedlings, which is indicative of increased ethylene sensitivity. The expression of the mannanase2 gene is upregulated in Sl-ERF2-overexpressing seeds, suggesting that Sl-ERF2 stimulates seed germination through the induction of the mannanase2 gene. It is noteworthy that the exaggerated hook phenotype is abolished when ethylene perception is blocked, strongly suggesting that Sl-ERF2 requires other ethylene-dependent components to impact the hook formation process

Etiology, distribution, treatment modalities and complications of maxillofacial fractures

Purpose: This study evaluated the trends and factors associated with maxillofacial fractures treated from 1997 to 2007 in the Oral and Maxillofacial Surgery Department of the Clermont-Ferrand University Hospital. Material and Methods: This study included 364 patients of which 82% were men and 45%, 20-29-years old. The etio- logy, anatomical distribution, treatment modality and complications of maxillofacial fractures were examined. Results: Overall, interpersonal violence, traffic accidents and falls were the most common mechanisms of injury. There was a decreasing trend in traffic accidents and increasing one in falls as a cause of fracture over the 11-years period of this study. Young male patients were preferentially victim of interpersonal violence and traffic accidents, while middle-aged ones were of falls and work-related accidents. Middle-aged female patients were preferentially victim of traffic accidents and interpersonal violence, while older ones were of falls. And the number of fractures per patient varied according to the mechanism of injury: low after work-related accidents and high after traffic accidents. About two-third of fractures involved the mandible. Most of these mandibular fractures were treated by osteosynthesis with or without intermaxillary fixation, with the proportion of the latter increasing over time. There were very few postoperative infections and only in mandible. Conclusions: Maxillofacial fractures predominantly occur in young men, due to interpersonal violence. There is nevertheless an increasing trend in falls as a cause of fracture, especially in female patients, consistent with the increasing trend in presentation of older people. Most maxillofacial fractures involve the mandible and there is an increasing trend in treating these fractures by osteosynthesis without intermaxillary fixation. Antibiotic prophy - laxis associated with dental hygiene care can be indicated to prevent postoperative infections

Two new metal–organic framework structures derived from terephthalate and linear trimetallic zinc building units

Two new zinc-terephthalate MOFs, (H2NEt2)[Zn3(BDC)3(HCO2)]1.5DEF (1) and Zn4(BDC)3(HCO2)2(DEF)4(2), based on trinuclear zinc secondary building units have been solvothermally synthesized from the well-studied MOF-5 system Zn–H2BDC–DEF (H2BDC = 1,4-benzenedicarboxylic acid or terephthalic acid; DEF = N,N-diethylformamide). It is shown that adding small amounts of formic acid to this system has a great influence on the formation of 3D networks based upon trimetallic zinc building units Zn3(O2CR)6. The structures of 1 and 2 comprise stacked 36 tessellated 2D zinc-terephthalate layers which are linked into 3D frameworks either by bridging formate monoanions (1) or by in situ generated neutral bridging units Zn(HCO2)2(DEF)4 (2). Flowing supercritical-CO2 activation of 1 led to a partially (80%) desolvated and probably collapsed structure (1-SC) with a measured BET (Brunauer–Emmett–Teller) surface area of 38 m2 g-1

Efficiency of dispersive wave generation in dual concentric core microstructured fiber

We describe the generation of powerful dispersive waves that are observed when pumping a dual concentric core microstructured fiber by means of a sub-nanosecond laser emitting at the wavelength of~1064 nm. The presence of three zeros in the dispersion curve, their spectral separation from the pump wavelength, and the complex dynamics of solitons originated by the pump pulse break-up, all contribute to boost the amplitude of the dispersive wave on the long-wavelength side of the pump. The measured conversion efficiency towards the dispersive wave at 1548 nm is as high as 50%. Our experimental analysis of the output spectra is completed by the acquisition of the time delays of the different spectral components. Numerical simulations and an analytical perturbative analysis identify the central wavelength of the red-shifted pump solitons and the dispersion profile of the fiber as the key parameters for determining the efficiency of the dispersive wave generation process.Comment: 11 pages, 12 figure

Bragg-Scattering conversion at telecom wavelengths towards the photon counting regime

9openopenKatarzyna Krupa; Alessandro Tonello; Victor Kozlov; Vincent Couderc; Philippe Di Bin; Stefan Wabnitz; Alain Barthelemy; Laurent Labonte; Sebastien TanzilliKatarzyna, Krupa; Alessandro, Tonello; Kozlov, Victor; Vincent, Couderc; Philippe Di, Bin; Wabnitz, Stefan; Alain, Barthelemy; Laurent, Labonte; Sebastien, Tanzill

Plasmodium vivax-like genome sequences shed new insights into Plasmodium vivax biology and evolution

Although Plasmodium vivax is responsible for the majority of malaria infections outside Africa, little is known about its evolution and pathway to humans. Its closest genetic relative, P. vivax-like, was discovered in African great apes and is hypothesized to have given rise to P. vivax in humans. To unravel the evolutionary history and adaptation of P. vivax to different host environments, we generated using long- and short-read sequence technologies 2 new P. vivax-like reference genomes and 9 additional P. vivax-like genotypes. Analyses show that the genomes of P. vivax and P. vivax-like are highly similar and colinear within the core regions. Phylogenetic analyses clearly show that P. vivax-like parasites form a genetically distinct clade from P. vivax. Concerning the relative divergence dating, we show that the evolution of P. vivax in humans did not occur at the same time as the other agents of human malaria, thus suggesting that the transfer of Plasmodium parasites to humans happened several times independently over the history of the Homo genus. We further identify several key genes that exhibit signatures of positive selection exclusively in the human P. vivax parasites. Two of these genes have been identified to also be under positive selection in the other main human malaria agent, P. falciparum, thus suggesting their key role in the evolution of the ability of these parasites to infect humans or their anthropophilic vectors. Finally, we demonstrate that some gene families important for red blood cell (RBC) invasion (a key step of the life cycle of these parasites) have undergone lineage-specific evolution in the human parasite (e.g., reticulocyte-binding proteins [RBPs])