Transient Response of the Head Kinematics - Influence of a Disturbed Visual Flow

Vision influences the controlled kinematics of human body. Previous studies have shown the influence of vision on head stabilization or whole posture. However, latencies between the stimuli and the head motion have never been quantified. The aim of this study is to quantify the influence of a perturbed vision on the head kinematics. Seven healthy volunteers without uncorrected vision (26.7±6.9 years old, 1 female, 2 right-handed/right-dominant eye, 5 right-handed/left-dominant eye) were studied. Visual stimuli were performed through an immersive personal 3D viewer (HMZ-T1, Sony), securely tied on the head. Motion analysis of the head and the torso were performed using the optoelectronic Vicon system (100Hz). Three markers were glued on the personal viewer, close to the nasion, left and right tragus, in order to create the head frame. Three markers were glued to create the torso frame (both acromia and C7). Two different 3D animated scenes were created on Blender and displayed at 24Hz. The first animation was a landscape with a ball rolling on the ground, and then the ball stopped before being virtually launched via a catapult toward the screen. Two velocities were programmed: 4.67 and 10.58 m.s-1. The second animation was a beach with sea and sky, where horizon tilted anticlockwise at 2 different constant rates: 0.24 deg.s-1 and 0.48 deg.s-1 with maximal amplitude of 8° and 16° respectively. The motion of the head relative to the torso was calculated for both scenes on seated and upright position, at the 2 different velocities, 2 times each, for a total of 16 random tests on each volunteer. For the launched ball animated scene, the reaction time seated was, as expected, shorter for the fast launches. For the beach animated scene, the head profiles followed most of the time the kinematic profile of the tilted animation, linearly or by steps, and not necessary until the end. Volunteers who were right-handed and right dominant eye tilted their head clockwise, at the inverse of the stimuli. Both experiments confirmed that visual stimulus could influence the kinematics of the head-neck system. In the ball animation, velocity of the stimulus does not seem to affect the amplitude of movement. In the beach animation, the head motions were variable, but performed at the same mean speed than the stimuli. Furthermore, the limited number of volunteer cannot conclude on the direction of rotation of the head, depending of the dominant hand and eye

Management plan for sustainable tourism at the Houtman Abrolhos Islands

The combination of unique species of fish, coral reefs and other invertebrates, historical shipwrecks and the commercially valuable Western rock lobster makes the Abrolhos a unique area of Western Australia. In recognition of this the Minister of Fisheries is releasing the plan \u27Management of Houtman Abrolhos System\u27, following a period of public consultation. The islands are becoming increasingly popular destination for tourists that are attracted to the diving, fishing, bird watching, maritime history and other features of the Abrolhos. The draft Management Plan for Sustainable Tourism in the Houtman Abolhos Islands has been developed to provide a framework within which tourism can be developed on the islands. The goal of the draft Management Plan for Sustainable Tourism at the Houtman Abrolhos Islands is to: Manage environmentally senstive nature-based tourism which is constent with the values of the Abrolhos System and provides appropriated access to the area for the community

Future directions for tourism at the Houtman Abrolhos Islands - draft for public comment

This paper discusses the constraints on tourism in the Abrolhos and key management strategies of the draft tourism plan. Discusses facilities required and recommending a broadening of air services to allow their use for tourism, establishment of boat moorings for commercial tourist operators, public moorings may be installed and rented for use by private boats, upgrading of facilites Dransfield House on Beacon Island, could be used as an interpretive centre

A Model for Prediction of the Tidal Currents in the English Channel

A model for prediction of tidal currents in the English Channel is presented. It is based on the classical harmonic description of tides deduced from the spectral development of the luni-solar tidal potential. The spatial distribution of the characteristic parameters (intensity, phase, and direction of the maximum velocity vector, ellipticity of the hodograph) for the 26 harmonic constituents introduced in the prediction procedure are deduced from a numerical simulation of 1 month’s duration for the entire English Channel. Two kinds of documents can be produced from this model : instantaneous velocity fields over a given area, and time series of the intensity and the direction of the velocity vector at a given location, over a given period. Four examples of prediction are presented, corresponding to specific areas and over periods where tidal currents have actually been observed. The comparison between predictions and observations is very satisfactory

Trade-offs and synergies in the ecosystem service demand of urban brownfield stakeholders

Brownfield site redevelopment presents an opportunity to create urban green spaces that provide a wide range of ecosystem services. It is important, therefore, to understand which ecosystem services are demanded by stakeholders and whether there are trade-offs or synergies in this demand. We performed a quantitative survey of ecosystem service demand from brownfield sites that included all major stakeholder groups. Results showed that there was a strong trade-off between demand for services related to property development (e.g. ground strength and low flood risk) and all other services, which were linked to vegetated sites. There was a secondary, but weak, trade-off between demand for services of more ‘natural’ vegetated sites (e.g. with a biodiversity protection role) and those linked to aesthetics and recreation. Stakeholders with a strong preference for biodiversity protection formed a distinct group in their ecosystem service demands. While a ‘development’ vs ‘green space’ trade-off may be unavoidable, the general lack of strong trade-offs in demand for other services indicated that the creation of multifunctional greenspaces from former brownfield sites would be desirable to most stakeholders, as long as these are biophysically possible

Bayesian inference of vorticity in unbounded flow from limited pressure measurements

We study the instantaneous inference of an unbounded planar flow from sparse noisy pressure measurements. The true flow field comprises configurations of one or more regularized point vortices of various strength and size. We interpret the true flow's measurements with a vortex estimator, also consisting of regularized point vortices, and attempt to infer the positions and strengths of this estimator assuming little prior knowledge. This problem often has several possible solutions, many due to a variety of symmetries -- particularly, the invariance of pressure to the sign of vortex strength. To deal with this ill-posedness and quantify the uncertainty, we develop the vortex estimator in a Bayesian setting. We use Markov-chain Monte Carlo techniques and a Gaussian mixture model to sample, characterize, and categorize the probable vortex states in the posterior distribution, tailoring the prior to avoid spurious solutions that arise from symmetries. The eigensystem of the true covariance illuminates rank deficiency and problematic directions in the state space. Through experiments with one or more true vortices, we reveal many aspects of the vortex inference problem. With fewer sensors than states, the estimator can only infer a manifold of equally-possible states. Using one more sensor than states ensures that no cases of rank deficiency arise. Uncertainty grows rapidly with distance when a vortex lies outside of the vicinity of the sensors. Vortex size cannot be reliably inferred, but the position and strength of a larger vortex can be estimated with a much smaller one. In estimates of multiple vortices their individual signs are discernible because of the vortices' non-linear coupling in the pressure. When the true vortex state is inferred from an estimator of fewer vortices, the estimated state approximately aggregates the true vortices where such aggregations are possible.Comment: 32 pages, 20 figure

Information needs and thematic priorities of the organic food and farming sector in France

A large survey was performed among a wide range of actors covering the areas of experimentation and research, processing and distribution, extension services, education and administration, all more or less committed in OF&F, to identify their information needs. This survey highlights the need for increased information dissemination. This analysis identifies four different publics with specific needs. Professional experience, degree of commitment to OF&F and professional category are structuring variables. Legal and economic information on food quality and processing is generally of interest to senior actors who have the lowest information needs. On the contrary, junior actors actively involved in the developmental and educational aspects of OF&F have the greatest information needs over a wide range of themes. Thematic priorities are also different depending on professional categories and types of information. While technicians and farmers call for scientific and technical information on plant production issues, only young farmers in OF&F give priority to animal production issues. The dataset must be further analysed but it already provides insights for recommendations on information dissemination and research priority setting