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The aim of this study was to investigate the hold-by-hold climbing fluency dynamics by using an instrumented holds system that measured the contact time on each hold. Forty-four competitive climbers have been analysed in a regional lead climbing competition during a route composed of 41 instrumented holds on 11 m high artificial climbing wall and with a grade of difficulty 6b on the French scale (IRCRA reported scale: 13). After removing 10 climbers who fell before the top of the route, the 34 remaining climbers who completed the route were clustered according to their total contact time on each hold. The hierarchical cluster analysis distinguished four profiles of climbing fluency dynamics, on the basis of six 'crux' points, showing that the fastest climbers at the crux points were those with the shortest climbing time. This new instrumented-holds system appeared very innovative as it provides an instantaneous feedback to coaches regarding inter-limbs fluency and subsequent motor organisations.

International audience; In this paper, we focus mainly on formation control of a swarm of UAV's tracking a moving target on a non regular mountainous surface. The main objective is to show how to dispatch the whole swarm of the quadrotors around the target (climber) with respect to the natural environment (mountain) taking advantage as much as possible from the free space surrounding the climber. The formation shape adapts with the neighbour environment topology, so that it avoids the collision with the environment and the concealing of the target from the UAV's cameras sights, and ensures as well the formation compactness and its closure to the target respecting the agent-agent and the agent-target security distances. The algorithm to define the free and safe hovering space (SHS) is then demonstrated with other two-steps algorithm to determine for each agent its desired position within the SHS. This work, that is considered as an introduction for upcoming works, does not miss to provide a simple control for each individual agent based on an established and corrected approximate dynamic model. The main idea to resolve this problem is explained in 2D and will be expanded for 3D environment, with other necessary and complementary enhancements. Keywords: UAVs control, formation control, target tracking, surveillance, film-making, 3D reconstruction, monitoring, quadrotor modeling.

International audience; Speed climbing involves an optimization of the velocity of the ascent and the trajectory path during performance. Consequently, any amount of energy spent in the two other directions than vertical, namely the lateral direction and the direction perpendicular to the wall plane, is a potential loss of performance. To assess this principle, we present a study on 3D motion analysis and its 3D visualization for a subject during a speed climbing performance. The fundamentals of geometrical measurement in 3D require to integrate multiple 2D cues, at least two, in order to extract 3D information. First results with two drones following an athlete's ascent show that a 3D velocity profile can be provided from the tracking of a marker on the harness, pointing critical phases in the ascent where the vertical speed is not dominant any more. We further investigate 3D motion of full body using markerless video-based tracking. Our approach is based on a full body 3D avatar model of the climber, represented as a 3D mesh. This model and its deformation are learned in a laboratory studio. The learning needs to be done only once. Result is a manifold embedding of the 3D mesh and its deformations, which can be used afterwards to perform registration onto video of performance of speed climbing. The results of the tracking is an inference of the 3D mesh aligned onto videos of speed climbing performance. From this 3D mesh, we deduce an estimation of the center of mass (COM). We show that this estimation from 3D mesh differs from the usual approximation of the COM as a marker on the harness. In particular, the 3D mesh COM takes into account the whole body movement such as the influence of the limbs which is not detected by a marker on the harness.

Limited data are available on the contribution of wildlife to the spread of antibacterial resistance. We determined the prevalence of resistance to antibiotics in Escherichia coli isolates collected from wild animals in 2013 and 2014 and the genetic basis for resistance to third-generation cephalosporin in Guadeloupe. We recovered 52 antibiotic-resistant (AR) E. coli strains from 48 of the 884 (5.4%) wild animals tested (46 iguanas, 181 birds, 289 anoles, and 368 rodents at 163 sampling sites). Rodents had higher rates of carriage (n = 38, 10.3%) than reptiles and birds (2.4% and 1.1%, respectively, p < 0.001). A significant association (p < 0.001) was found between the degree of anthropization and the frequency of AR E. coli carriage for all species. The carriage rate of ciprofloxacin- and cefotaxime-resistant isolates was 0.7% (6/884) and 1.5% (13/884), respectively. Most (65.4%) AR E. coli were multi-drug resistant, and the prevalence of extended-spectrum beta-lactamase (ESBL)-producing E. coli was low (n = 7, 0.8%) in all species. Eight ESBL-producing E. coli were recovered, two genetically unrelated isolates being found in one bird. These isolates and 20 human invasive ESBL E. coli isolates collected in Guadeloupe during the same period were investigated by whole genome sequencing. blaCTX–M–1 was the only ESBL gene shared by three animal classes (humans, n = 2; birds, n = 2; rodents, n = 2). The blaCTX–M–1 gene and most of the antimicrobial resistance genes were present in a large conjugative IncI1 plasmid that was highly similar (>99% nucleotide identity) to ESBL-carrying plasmids found in several countries in Europe and in Australia. Although the prevalence of ESBL-producing E. coli isolates was very low in wild animals, it is of concern that the well-conserved IncI1 plasmid-carrying blaCTX–M–1 is widespread and occurs in various E. coli strains from animals and humans.

Since the Summer Youth Olympic Games (YOG) 2018, hosted in Buenos Aires, Argentina, sport climbing is an official event of the Olympic Games program as a combine event. The climbers have to perform...

International audience; The epidemiology of human Salmonella enterica infections in Guadeloupe (French West Indies) appears to be specific, with a higher prevalence of the subspecies enterica serovars Panama and Arechavaleta (Panama and Arechavaleta) than in other regions. A study was performed in Guadeloupe to identify the reservoir of Salmonella serovars by comparing their distribution in warm- and cold-blooded animals and in humans living in Guadeloupe and mainland France. Furthermore, a case-control study was conducted in 2012-2013 to identify the main epidemiologic risk factors for S. enterica infection among children under 15 years of age. Between June 2011 and December 2014, feces from 426 reptiles (322 anoles, 69 iguanas and 35 geckos) and 50 frogs distributed throughout Guadeloupe and nearby islands were investigated. The frequency of S. enterica carriage was 15.0% (n = 64) in reptiles but varied by species. The only significant risk factor for S. enterica infection was a more frequent presence of frogs in the houses of cases than in those of controls (P = 0.042); however, isolates were not collected. Panama and Arechavaleta were the two serovars most often recovered between 2005 and 2014 from humans living in Guadeloupe (24.5% (n = 174) and 11.5% (n = 82), respectively), which is in contrast to the low prevalence in mainland France (0.4%). Their presence at low frequencies in wild reptiles (4.6% (n = 3) and 3.1% (n = 2), respectively) and pigs (7.5% (n = 5) and 1.5% (n = 1), respectively) suggests a broad host range, and humans may be infected by indirect or direct contact with animals. These serovars are probably poorly adapted to humans and therefore cause more severe infections. The unusual subspecies houtenae serovar 43:z4,z32:- was a major subspecies in wild reptiles (24.6%, n = 16) and humans (9.4%, n = 67) but was not recovered from warm-blooded animals, suggesting that reptiles plays a key role in human infection.

Triadobatrachus massinotiis a batrachian known from a single fossil from the Early Triassic of Madagascar that presents a combination of apomorphic salientian and plesiomorphic batrachian characters. Herein we offer a revised description of the specimen based on X-ray micro-tomography data. We report previously unknown caudal vertebrae, possible mentomeckelians, and hidden parts of other structures. We also confirm the presence of a ventrolateral ledge on the opisthotic, and we rectify some previous interpretations. There are no cervical ribs and the jaw may have had an angular. The presacral region is composed of 15 vertebrae with a unique atlas-axis complex instead of 14 vertebrae with a bipartite atlas. The configuration of the pelvic girdle is not very clear, although it is likely more plesiomorphic than the anuran- like condition previously assumed. Our re-assessment of the saltatorial performance of Triadobatrachussupports the traditional interpretation that this animal was not a specialised jumper. In order to assess the sequence of events in the early evolution of the salientian morphotype, we estimated the ancestral length of the trunk region of batrachians under different hypotheses of lissamphibian relationships and divergence times. Most of our results suggest that some trunk reduction took place before the divergence of caudates and salientians (presumably in the Permian), and that the trunk of Triadobatrachusmostly reflects this ancestral condition. Thus, trunk reduction possibly preceded the anteroposterior elongation of the ilia and the shortening of the tail seen in Triadobatrachus. We also provide an updated review of the data relevant for the use of Triadobatrachusas a calibration constraint in molecular divergence age analyses that meets recently-suggested standards.

This study provides a morphometric data set of body segments that are biomechanically relevant for locomotion in two ecomorphs of adult male anoles, namely, the trunk-ground Anolis sagrei and the trunk-crown Anolis carolinensis. For each species, 10 segments were characterized, and for each segment, length, mass, location of the center of mass, and radius of gyration were measured or calculated, respectively. The radii of gyration were computed from the moments of inertia by using the double swing pendulum method. The trunk-ground A. sagrei has relatively longer and stockier hindlimbs and forelimbs with smaller body than A. carolinensis. These differences between the two ecomorphs demonstrated a clear relationship between morphology and performance, particularly in the context of predator avoidance behavior, such as running or jumping in A. sagrei and crypsis in A. carolinensis. Our results provide new perspectives on the mechanism of adaptive radiation as the limbs of the two species appear to scale via linear factors and, therefore, may also provide explanations for the mechanism of evolutionary changes of structures within an ecological context.

Predator–prey interactions are probably one of the key mechanisms for explaining the evolution of organisms in their ecosystems. Scientific fields relevant to understanding the mechanisms of these interactions are as diverse as evolutionary biology, behavioral ecology, ecomorphology, molecular biology, phylogeny, neurosciences, physiology, biomechanics, and robotics. The difficulty in understanding these mechanisms lies therefore (1) in the multi- and interdisciplinary nature of this issue, and (2) in keeping up with very rapid developments in various scientific fields. This Special Issue provides an interdisciplinary approach to predator–prey interactions to identify how phenotypic traits of both types of organisms interact and how each can act as a selective pressure on the evolution of a population of organisms at the different levels of the trophic chain. Moreover, we show that confronting bodies of knowledge that a priori appear as remote as those of robotics and experimental biology or ecology may seem difficult but can provide reciprocal understanding.

In arboreal animals such as the grey mouse lemur (Microcebus murinus Miller, 1777), leaping is the most frequent strategy for predator avoidance. The aim of this study was to characterise the locomotor adaptation in response to the structural constraint of the habitat (i.e., position of the landing substrate). Thus, we characterised the push-off phase by inducing the lemurs to leap up to a range of heights from horizontal to their own individual highest performance. Using uniplanar high-frequency cineradiographs collected in a sagittal plane, the relative contributions of the centre of mass (CoM) velocity vector magnitude and orientation to leaping performance were evaluated. The kinematics of the push-off phase showed that for low landing heights, leaping performance was essentially due to hip and knee extensions. Higher leaps seemed to be related to an increase in ankle contribution. At all leaping heights, the proximal-to-distal sequence of the hind limb joints controlled the orientation and magnitude of the M. murinus CoM velocity vector while pushing off. Finally, the analysis of the velocity vector at the onset of take-off suggested that the optimal solution for predator avoidance was to leap for horizontal distance and not for vertical distance.

This paper discusses on the role of joint temporal sequence while moving a two-dimensional arm from an initial position to targets into the fingertip workspace in humans. For this purpose, we proposed a general monotonic model of joint asymmetric displacement. Optimization consisted in minimizing least square dis-placement of either fingertip or arm centre of mass from arm initial position to four targets located into fin-gertip workspace, i.e. contralaterally and ipsilaterally. Except for 60° ipsilateral target, results of the simula-tion presented in all cases temporal sequences of the shoulder, the elbow and the wrist. We concluded that primary function of proximal-to-distal or distal-to-proximal joint sequence is to flatten the trajectory of the fingertip or body centre of mass.

The workspace of a serial manipulators is defined as the area covered by its extremity for a finite number of degrees of freedom. In order to define its boundaries, a pure geometrical interpretation of the jacobian’s property is applied, in opposite to the specific methods or symbolic calculation as proposed in the literature. This solution leads to a general and exact description of the boundaries, independent of the number of degrees of freedom in the planar case and compatible with real-time computation as required in robotics.

Resume On modelise un systeme polyarticule plan par les points definissant les articulations et un dernier point A p lie au dernier corps. L'espace balaye par le point A p a sa frontiere definie par 3 types de courbes correspondants a des configurations singulieres. Ces courbes peuvent etre determinees geometriquement. Pour citer cet article : J. Bastien et al., C. R. Mecanique 335 (2007).

This study investigated the influence of the covering swimsuit and the fabric surface properties on the butterfly stroke kinematics. Surface properties were evaluated by wetting measurements of two fabric samples: one for training suits and one for competition suits. The surface of the second one was coated by mechanochemical treatment in order to modify its surface properties. Nine national level swimmers performed a 50-m butterfly at submaximal velocity in three swimsuit conditions: conventional, long, and coated long swimsuits. From video recording, the hip was digitized at the entry and exit of the swimmer's hand in order to calculate the duration, hip displacement, and hip linear velocity during underwater and recovery phases and during stroke. The results for wetting show that competition fabric was more water-repellent than training fabric, but both were isotropic. Moreover, the mechanochemical treatment increased water repellency and anisotropy. The swimming results indicated that, when compared to a conventional swimsuit, wearing a coated long swimsuit increased hip linear velocity during stroke, and particularly during the recovery phase which had a shorter duration. These results suggest that the covering swimsuit should be coupled with the water repellent and anisotropic properties of the fabric surface in order to improve swimming performance.

The purpose of this study was to investigate the behaviour of the human soleus muscle during isometric contraction. A model taking into account the musculoskeletal geometry, the musculotendon architecture and the neural excitation input has been developed. The neural excitation input was simulated using a recruitment and firing rate organisation model. The musculotendon actuator was modelled as a tendon inserted in series with fibres defined by a contractile component in parallel with an elastic component. At maximal neural excitation, the model highlighted the functional significance of tendon stiffness and pennation angle. These architectural parameters tended to increase the operative ankle joint angle range of the soleus actuator, either to the maximal plantarflexion positions for the pennation angle or to the maximal dorsiflexion positions for tendon elasticity. When the model was simulated under various neural excitation levels, it predicted a displacement of the soleus fibre optimal length towards the soleus long length (maximal dorsiflexion position) with increasing neural excitation. The study concluded that the effect of muscular architecture should be taken into account to analyse the effect of neural excitation level on isometric force output.

In birds, the neck/head system, the beak, and the hyolingual structures show an exceptional degree of variation under the adaptive pressure that arose from the diversity of exploited food (Homberge...

International audience; Hydroxyindole-O-methyltransferase (HIOMT) catalyzes the final step of melatonin biosynthesis and appears to be specifically expressed in the pineal gland and in the retina. This review deals with the regulation of HIOMT by environmental light and with the developmental aspects of HIOMT expression in chicken and rat. Early studies based on HIOMT activity measurements and more recent studies involving cDNA hybridization to HIOMT mRNA are taken into consideration. Together, the data reveal that long term regulation of HIOMT by light would rely on a day/night rhythm of HIOMT gene transcription, coupled to a slow turnover of the protein. Rapid changes in HIOMT mRNA levels and early expression during embryonic development suggest that further studies on this gene may shed light on the molecular mechanisms involved in the differentiation of the melatoninergic function and in its regulation by light, both in the pineal gland and in the retina.

Tetrapods with highly different morphologies occupy ecological niches of the canopy making them ideal for testing the evolution of structures and performances under similar environmental selective pressures. We compared leap up strategies between two distantly related amniote species, Anolis carolinensis (Squamate) and Microcebus murinus (Lemuriform) known to use leaping as their major locomotor mode for predator avoidance. Our comparative analysis and model show that leaping strategies (flat jump trajectory in horizontal leaps, use of forelimbs in landing) are similar in both species. The most striking divergence concerns only the temporal joint sequence accommodation to leaping height, although an identical proximal-to-distal sequence is observed when both taxa leap to maximal height. We suggest a convergent exaptation of leaping biomechanics among arboreal amniotes, which reflects similar biomechanical constraints and evolutionary pressures in these animals.

Detecting and locating prey are key to predatory success within trophic chains. Predators use various signals through specialized visual, olfactory, auditory or tactile sensory systems to pinpoint their prey. Snakes chemically sense their prey through a highly developed auxiliary olfactory sense organ, the vomeronasal organ (VNO). In natricine snakes that are able to feed on land and water, the VNO plays a critical role in predatory behavior by detecting cues, known as vomodors, which are produced by their potential prey. However, the chemical nature of these cues remains unclear. Recently, we demonstrated that specific proteins-parvalbumins-present in the cutaneous mucus of the common frog (Rana temporaria) may be natural chemoattractive proteins for these snakes. Here, we show that parvalbumins and parvalbumin-like proteins, which are mainly intracellular, are physiologically present in the epidermal mucous cells and mucus of several frog and fish genera from both fresh and salt water. These proteins are located in many tissues and function as Ca(2+) buffers. In addition, we clarified the intrinsic role of parvalbumins present in the cutaneous mucus of amphibians and fishes. We demonstrate that these Ca(2+)-binding proteins participate in innate bacterial defense mechanisms by means of calcium chelation. We show that these parvalbumins are chemoattractive for three different thamnophiine snakes, suggesting that these chemicals play a key role in their prey-recognition mechanism. Therefore, we suggest that recognition of parvalbumin-like proteins or other calcium-binding proteins by the VNO could be a generalized prey-recognition process in snakes. Detecting innate prey defense mechanism compounds may have driven the evolution of this predator-prey interaction.

SUMMARYThe purpose of this study was to investigate the pattern of coordinations of the hindlimb joints in the world's smallest living primate (Microcebus murinus). The sequencing and timing of joint rotations have been analyzed in five adult males performing maximal leaping from a take-off immobile platform to their own wooden nest. Angular kinematics of hip, knee, angle and metatarso-phalangeal (MT) joints were deduced from high-speed X-ray films in the sagittal plane of the animals. The body mass center (BMC) of the lemurs was assimilated to their iliac crest. The maximal airborne performance of the lemurs was 0.33±0.04 m, which represented 2.55±0.36 times their snout–vent length. Take-off instant occurred 72±7 ms after the start of the push-off, with a BMC velocity of 3.23±0.48 m s−1, oriented 55±14 deg. with the horizontal plane. The kinematic analysis of the joints and musculo-tendon architecture of the M. murinus plantar flexors pointed out mechanical power amplifier mechanisms (i.e. stretch-shortening cycle of hindlimb muscles and proximo-to-distal sequence).

To our knowledge jumping kinematics have never been studied in elderly persons. This study was aimed at examining the influence of aging on vertical jump performance and on interjoint coordination. Two groups of adults, 11 young men ages 18–25 years and 11 older men ages 79–100 years, were filmed while performing a maximal squat jump. Compared to young adults, jump height was significantly decreased by 28 cm in the elderly. Older adults spontaneously jumped from a more extended position of the hip. Results showed a decrease in hip, knee, and ankle linear velocity and angular amplitude with aging. The decrease in jump height was attributed to a decrease in explosive force and in the range of shortening of extensor muscles. In agreement with the literature, a proximo-distal coordination pattern was observed in young adults. Older adults used a simultaneous pattern. This may indicate that adults adjust their pattern of joint coordination as they age.

This study examined whether providing verbal instructions plus demonstration and task repetition facilitates the early acquisition of a sport skill for which learners had a prior knowledge of the individual motor components. After one demonstration of the task by an expert, 18 novice skaters practiced a figure skating jump during a 15-min. period. Subjects were randomly assigned to one of 3 groups: a group provided with a verbal instruction that specified the subgoals of the task (Subgoals group), a group provided with a verbal instruction that used a metaphor (Metaphoric group), and a group not receiving any specific instruction during training (Control group). Subjects were filmed prior to and immediately following the practice session. Analysis indicated that the modifications of performance were related to the demonstration and the subsequent task repetitions only. Providing additional verbal instructions generated no effect. Therefore, guiding the learner toward a solution to the task problem by means of verbal instruction seems to be ineffective if done too early in the course of learning.

The purpose of this study was to investigate the influence of wearing figure skating skates on vertical jump performance and interjoint co-ordinations described in terms of sequencing and timing of joint rotations. Ten national to international figure skaters were filmed while performing a squat jump (SJ) on a force platform. Three experimental conditions were successively realized: barefoot (BF), lifting a 1.5 kg weight (LW) corresponding to the skates' mass, attached on the distal extremity of each leg and wearing skates (SK). Jump height, angular kinematics as well as joints kinetics were calculated. Relative to the SJ height reached in the BF condition, SJ performance was significantly decreased by 2.1 and 5.5 cm in the LW and SK conditions, respectively. The restriction of ankle amplitude imposed by wearing skates was found to significantly limit the knee joint amplitude while the hip angular motion was not affected. Neither the skates' mass nor the limited ankle angular motion modified the proximo-distal organization of joint co-ordination observed when jumping barefoot. However, with plantar flexion restriction, the delay between hip and knee extensions increased while it was reduced between knee and ankle extensions. Work output at the knee and ankle joints were significantly lowered when wearing skates. The decrease of work at the knee was shown to result from an early flexing moment causing a premature deceleration of the knee and from a reduction of knee amplitude. Taken together, these results show a minimization of the participation of the knee when plantar flexion is limited. It was proposed that constraining the distal joint causes a reorganization of interjoint co-ordinations and a redistribution of the energy produced by knee extensors to the hip and ankle joints.

Ethology and behavioural ecology provide conceptual frameworks in the comparative study of the behaviour of humans and animals (Lorenz and Kickert 1981; Krebs and Davies 1997). In other words, thes...

The main purpose of this study was to investigate the joined behaviours of tendon and pennation angle during maximal isometric contractions. A musculotendon model of the human soleus muscle was simulated as a function of ankle joint position, which determines the soleus length. Analysis of the respective values of tendon length and pennation angle for various musculotendon lengths showed that the primary effects of tendon elasticity and pennation angle variation were to reduce the fibre length variations by absorption of the musculotendon lengthening. The efficiency of this reduction process was the highest at short soleus lengths and principally related to tendon length variations. Finally, it was suggested that the optimal solution for musculotendon actuators acting in high lengthening ranges were long tendon units and great pennation angles. The heuristic model used in this study highlighted the existence of some dynamic phenomena inside the actuator. However, it did not pretend to represent the overall complexity of the mechanical interactions between the different elements composing the soleus architecture.