Éclatement et contraction lagrangiens et applications

Soit (M, ω) une variété symplectique. Nous construisons une version de l’éclatement et de la contraction symplectique, que nous définissons relative à une sous-variété lagrangienne L ⊂ M. En outre, si M admet une involution anti-symplectique ϕ, et que nous éclatons une configuration suffisament symmetrique des plongements de boules, nous démontrons qu’il existe aussi une involution anti-symplectique sur l’éclatement ~M. Nous dérivons ensuite une condition homologique pour les surfaces lagrangiennes réeles L = Fix(ϕ), qui détermine quand la topologie de L change losqu’on contracte une courbe exceptionnelle C dans M. Finalement, on utilise ces constructions afin d’étudier le packing relatif dans (ℂP²,ℝP²).Given a symplectic manifold (M,ω) and a Lagrangian submanifold L, we construct versions of the symplectic blow-up and blow-down which are defined relative to L. Furthermore, if M admits an anti-symplectic involution ϕ, i.e. a diffeomorphism such that ϕ2 = Id and ϕ*ω = —ω , and we blow-up an appropriately symmetric configuration of symplectic balls, then we show that there exists an antisymplectic involution on the blow-up ~M as well. We derive a homological condition for real Lagrangian surfaces L = Fix(ϕ) which determines when the topology of L changes after a blow down, and we then use these constructions to study the real packing numbers for real Lagrangian submanifolds in (ℂP²,ℝP²)

Developing a corpus of strategic conversation in The Settlers of Catan

International audienceWe describe a dialogue model and an implemented annotation scheme for a pilot corpus of annotated online chats concerning bargaining negotiations in the game The Settlers of Catan. We will use this model and data to analyze how conversations proceed in the absence of strong forms of cooperativity, where agents have diverging motives. Here we concentrate on the description of our annotation scheme for negotiation dialogues, illustrated with our pilot data, and some perspectives for future research on the issue

Divergence of Voronoi Cell Anisotropy Vector: A Threshold-Free Characterization of Local Structure in Amorphous Materials

Characterizing structural inhomogeneity is an essential step in understanding the mechanical response of amorphous materials. We introduce a threshold-free measure based on the field of vectors pointing from the center of each particle to the centroid of the Voronoi cell in which the particle resides. These vectors tend to point in toward regions of high free volume and away from regions of low free volume, reminiscent of sinks and sources in a vector field. We compute the local divergence of these vectors, where positive values correspond to overpacked regions and negative values identify underpacked regions within the material. Distributions of this divergence are nearly Gaussian with zero mean, allowing for structural characterization using only the moments of the distribution. We explore how the standard deviation and skewness vary with the packing fraction for simulations of bidisperse systems and find a kink in these moments that coincides with the jamming transition

Are people the problem or the solution? A critical look at the rise of the smart/intelligent building and the role of ICT enabled engagement

Almost 20 % of the UK’s energy consumption and CO2 emissions arise from non-domestic buildings. Behaviour change initiatives could have a significant impact given current estimates that around 30 % of energy in buildings is currently wasted. Most recently, the role of ICT and the digital economy has been championed as offering significant potential to contribute to carbon reduction targets within buildings. The creation of smart or intelligent buildings and increasingly sophisticated (and expensive) building energy management systems (BEMS) are viewed as step forward in cutting energy use by limiting the role of the building user. This paper takes a reflective stance in seeking to question the faith being placed in smart or intelligent buildings through asking, what role then for the building-user? The smart building approach appears to view the behaviour of users as a hurdle to overcome, rather than a resource to be utilized. At times it has had a narrow view of how technology and user-engagement can sit together. This paper suggests lessons can be learnt from other disciplines that champion the role of citizens and the benefits for user-engagement, participation and, increasingly, using digital technologies (such as smartphones and social media) to harness the co-creation of knowledge, collaboration and empowerment. A critical review of recent thinking in this area is presented before discussing the possible options available for organisations seeking to reduce the energy demand. Reflections are offered from a range of academic disciplines that shed light on the wider possibilities and opportunities digital technologies can offer for behaviour change and energy demand reduction in the non-domestic setting. For example, through enabling building users to both understand the environmental impact of their activities and to act in networks through social media applications of the digital technology

Pushing the mass limit for intact launch and photoionization of large neutral biopolymers

Since their first discovery by Louis Dunoyer and Otto Stern, molecular beams have conquered research and technology. However, it has remained an outstanding challenge to isolate and photoionize beams of massive neutral polypeptides. Here we show that femtosecond desorption from a matrix-free sample in high vacuum can produce biomolecular beams at least 25 times more efficiently than nanosecond techniques. While it has also been difficult to photoionize large biomolecules, we find that tailored structures with an abundant exposure of tryptophan residues at their surface can be ionized by vacuum ultraviolet light. The combination of these desorption and ionization techniques allows us to observe molecular beams of neutral polypeptides with a mass exceeding 20,000 amu. They are composed of 50 amino acids – 25 tryptophan and 25 lysine residues – and 26 fluorinated alkyl chains. The tools presented here offer a basis for the preparation, control and detection of polypeptide beams

Size and shape constancy in consumer virtual reality

With the increase in popularity of consumer virtual reality headsets, for research and other applications, it is important to understand the accuracy of 3D perception in VR. We investigated the perceptual accuracy of near-field virtual distances using a size and shape constancy task, in two commercially available devices. Participants wore either the HTC Vive or the Oculus Rift and adjusted the size of a virtual stimulus to match the geometric qualities (size and depth) of a physical stimulus they were able to refer to haptically. The judgments participants made allowed for an indirect measure of their perception of the egocentric, virtual distance to the stimuli. The data show under-constancy and are consistent with research from carefully calibrated psychophysical techniques. There was no difference in the degree of constancy found in the two headsets. We conclude that consumer virtual reality headsets provide a sufficiently high degree of accuracy in distance perception, to allow them to be used confidently in future experimental vision science, and other research applications in psychology

Demonstrations to Support Change to the >260 ppm Mercury Treatment Regulations

The U.S. Department of Energy (DOE) and the U. S. Environmental Protection Agency (EPA) are working together to justify a change in the Land Disposal Restriction for High Mercury (>260 ppm mercury) waste. The present regulation that requires roasting or retorting is based on recovering and recycling the mercury in the waste. However, most of DOE’s High Mercury waste is radioactively contaminated, eliminating the possibility of its recycle. The radioactive mercury recovered must be amalgamated and disposed. In addition, concern over fugitive emissions from retorting and roasting operations has raised the question of whether such processing is environmentally sound. A change to the regulation to allow stabilization and disposal would reduce the overall environmental threat, if the stabilization process can reduce the leachability of the mercury to regulatory levels. Demonstrations are underway to gather data showing that the High Mercury waste can be safely stabilized. At the same time, comparison tests are being conducted using an improved form of the baseline retorting technology to better quantify the fugitive emission problem and determine the full capability of thermal desorption systems. A first round of demonstrations stabilizing mercury in soil from Brookhaven National Laboratory (BNL) has been completed. Four groups demonstrated their process on the waste: 1) BNL demonstrated its Sulfur Polymer Stabilization/Solidification process; 2) Nuclear Fuel Services used their DeHg (de-merk) process, 3) Allied Technology Group used chemical stabilization, and 4) Sepradyne demonstrated their vacuum thermal desorption system. All groups were successful in their tests, reaching regulatory levels for mercury leachability. Data for each group will be presented. DOE, EPA, and the University of Cincinnati are presently working on another series of tests involving treatment of surrogate sludge and soil by commercial vendors. Protocols that better determine the waste form’s ability to withstand leaching are being used to analyze the stabilized surrogates. Results of these and the previous demonstrations will be used to determine whether the High Mercury treatment regulation can be safely changed

Organic farming provides reliable environmental benefits but increases variability in crop yields: a global meta-analysis

To promote food security and sustainability, ecologically intensive farming systems should reliably produce adequate yields of high-quality food, enhance the environment, be profitable, and promote social wellbeing. Yet, while many studies address the mean effects of ecologically intensive farming systems on sustainability metrics, few have considered variability. This represents a knowledge gap because producers depend on reliable provisioning of yields, profits, and environmental services to enhance the sustainability of their production systems over time. Further, stable crop yields are necessary to ensure reliable access to nutritious foods. Here we address this by conducting a global meta-analysis to assess the average magnitude and variability of seven sustainability metrics in organic compared to conventional systems. Specifically, we explored the effects of these systems on (i) biotic abundance, (ii) biotic richness, (iii) soil organic carbon, (iv) soil carbon stocks, (v) crop yield, (vi) total production costs, and (vii) profitability. Organic farms promoted biotic abundance, biotic richness, soil carbon, and profitability, but conventional farms produced higher yields. Compared to conventional farms, organic farms had lower variability in abundance and richness but greater yield variability. Organic farms thus provided a “win-win” (high means and low variability) for environmental sustainability, while conventional farms provided a “win-win” for production by promoting high crop yields with low variability. Despite lower yields, and greater yield variability, organic systems had similar costs to conventional systems and were more profitable due to organic premiums. Our results suggest certification guidelines for organic farms successfully promote reliable environmental benefits, but greater reliance on ecological processes may reduce predictability of crop production

Linear ubiquitin chain assembly complex coordinates late thymic T-cell differentiation and regulatory T-cell homeostasis.

The linear ubiquitin chain assembly complex (LUBAC) is essential for innate immunity in mice and humans, yet its role in adaptive immunity is unclear. Here we show that the LUBAC components HOIP, HOIL-1 and SHARPIN have essential roles in late thymocyte differentiation, FOXP3(+) regulatory T (Treg)-cell development and Treg cell homeostasis. LUBAC activity is not required to prevent TNF-induced apoptosis or necroptosis but is necessary for the transcriptional programme of the penultimate stage of thymocyte differentiation. Treg cell-specific ablation of HOIP causes severe Treg cell deficiency and lethal immune pathology, revealing an ongoing requirement of LUBAC activity for Treg cell homeostasis. These data reveal stage-specific requirements for LUBAC in coordinating the signals required for T-cell differentiation