Slow waves in locally resonant metamaterials line defect waveguides

In the past decades, many efforts have been devoted to the temporal manipulation of waves, especially focusing on slowing down their propagation. In electromagnetism, from microwave to optics, as well as in acoustics or for elastic waves, slow wave propagation indeed largely benefits both applied and fundamental physics. It is for instance essential in analog signal computing through the design of components such as delay lines and buffers, and it is one of the prerequisite for increased wave/matter interactions. Despite the interest of a broad community, researches have mostly been conducted in optics along with the development of wavelength scaled structured composite media, that appear promising candidates for compact slow light components. Yet their minimum structural scale prevents them from being transposed to lower frequencies where wavelengths range from sub-millimeter to meters. In this article, we propose to overcome this limitation thanks to the deep sub-wavelength scale of locally resonant metamaterials. In our approach, implemented here in the microwave regime, we show that introducing coupled resonant defects in such composite media allows the creation of deep sub-wavelength waveguides. We experimentally demonstrate that waves, while propagating in such waveguides, exhibit largely reduced group velocities. We qualitatively explain the mechanism underlying this slow wave propagation and first experimentally demonstrate, then numerically verify, how it can be taken advantage of to tune the velocity, achieving group indices ng as high as 227 over relatively large bandwidths. We conclude by highlighting the three beneficial consequences of our line defect slow wave waveguides in locally resonant metamaterials: the deep sub-wavelength scale, the very large group indices and the fact that slow wave propagation does not occur at the expense of drastic bandwidth reductions

Photo-assisted inkjet printing of antibodies onto cellulose for the eco?-friendly preparation of immunoassay membranes

International audienceThe current global issues have stimulated the search for both ecologically and economically friendly (eco?-friendly) materials and processes. As a sustainable and affordable biopolymer, cellulose is an ideal material for developing diagnostic devices. Recently, paper-based bioanalytical devices have trended towards three-dimensional microfluidic platforms allowing multiplex diagnosis. This technological mutation now challenges the production process of those devices. The whole design, as well as the biosensing material immobilization, should be as eco?-friendly as possible. To this end, the biomolecule immobilization process presented here combines a photolinker-free photografting procedure with inkjet printing which is a versatile and environmentally friendly dispensing method. While many printing cycles are usually achieved to get efficient immune answers, only one to five printing passes were sufficient in this study. Antibodies have been successfully printed and immobilized onto paper sheets. These membranes were further used to perform lateral flow immunoassays. The visual detection limits observed were identical to those usually displayed by the classical dispensing method, regardless the membrane material. The process developed herein is simple, time and cost-saving as well as environmentally friendly. More generally, it is a powerful tool for robust and abundant immobilization of chemical-sensitive proteins onto various cellulose-based papers and according to complex designs

One-step and eco-friendly modification of cellulose membranes by polymer grafting

International audienceThe increasing environmental awareness has stimulated the use of bio-based materials and processes. As an affordable and sustainable biopolymer, cellulose is an ideal engineering material. Beyond paper, cellulose finds applications in many areas such as composites, electronics and drug delivery. To fulfil these new functions, cellulose needs to acquire new properties, which is commonly done by graft polymerization of acrylic compounds. While cellulose modification is usually performed through complex and expensive procedures, the diazonium-based polymer grafting procedure presented here was performed in water, at room temperature, in a short single step. Cellulose sheets have been successfully grafted with several acrylic polymers, first globally through a dipping procedure and then locally by inkjet printing. The process developed herein is simple, eco-friendly and mostly time and cost-saving. More generally, it is a powerful tool for easy, robust and patterned graft copolymerization of cellulose sheets with various acrylic monomers and even bio-based monomer

Collaborative Virtual Training with Physical and Communicative Autonomous Agents

International audienceVirtual agents are a real asset in collaborative virtual environment for training (CVET) as they can replace missing team members. Collaboration between such agents and users, however, is generally limited. We present here a whole integrated model of CVET focusing on the abstraction of the real or virtual nature of the actor to define a homogenous collaboration model. First, we define a new collaborative model of interaction. This model notably allows to abstract the real or virtual nature of a teammate. Moreover, we propose a new role exchange approach so that actors can swap their roles during training. The model also permits the use of physically based objects and characters animation to increase the realism of the world. Second, we design a new communicative agent model, which aims at improving collaboration with other actors using dialog to coordinate their actions and to share their knowledge. Finally, we evaluated the proposed model to estimate the resulting benefits for the users and we show that this is integrated in existing CVET applications

On the pp-supports of a holonomic D\mathcal{D}-module

For a smooth variety $Y$ over a perfect field of positive characteristic, the sheaf $D_Y$ of crystalline differential operators on $Y$ (also called the sheaf of $PD$-differential operators) is known to be an Azumaya algebra over $T^*_{Y'},$ the cotangent space of the Frobenius twist $Y'$ of $Y.$ Thus to a sheaf of modules $M$ over $D_Y$ one can assign a closed subvariety of $T^*_{Y'},$ called the $p$-support, namely the support of $M$ seen as a sheaf on $T^*_{Y'}.$ We study here the family of $p$-supports assigned to the reductions modulo primes $p$ of a holonomic $\mathcal{D}$-module. We prove that the Azumaya algebra of differential operators splits on the regular locus of the $p$-support and that the $p$-support is a Lagrangian subvariety of the cotangent space, for $p$ large enough. The latter was conjectured by Kontsevich. Our approach also provides a new proof of the involutivity of the singular support of a holonomic $\mathcal{D}$-module, by reduction modulo $p.$Comment: The article has been rewritten with much improved exposition as well as some additional results, e.g. Corollary 6.3.1. This is the final version, accepted for publication in Inventiones Mathematica

Age of peak swim speed and sex difference in performance in medley and freestyle swimming – A comparison between 200 m and 400 m in Swiss elite swimmers

The aims of the present study were to examine (i) the age of peak swim speed and (ii) the sex difference in peak swim times in 200m and 400m medley versus freestyle. Swim times and ages of 5,524 swimmers (2,785 males and 2,739 females) from the Swiss high score list from 2006 to 2010 were analyzed using one-way analysis of variance (ANOVA). The age of peak swim speed was younger for females (~20-21 years) compared to males (~22-25 years) for both distances and both swimming styles. The sex differences in peak swim times for age group 10-39 years were 9.7% (SD=3.4) and 7.1% (SD=5.1) for 200m and 400m individual medley, and 10.1% (SD=5.0) and 6.1% (SD=4.0) for 200m and 400m freestyle, respectively. The sex differences were neither different between the two distances nor between the two disciplines (p > .05). There were no differences within each sex (i.e. females to females, and males to males) in the age of reaching peak swim speed in 200m and 400m individual medley and freestyle. However, females reached the peak swim speed at a younger age than males. The sex differences in peak swim times were similar for 200m than for 400m for both swim styles. To summarize, the present findings suggest no difference in the age of peak swim times in 200m and 400m individual medley and freestyle. However, females reached peak swim times earlier than males, which might be dependent on a different development of the genders in puberty and the related physiological and anthropometric factors. Sex differences in peak swim times were similar for 200m than for 400m for both swim styles

Adaptation of Proteins to the Cold in Antarctic Fish: A Role for Methionine?

The evolution of antifreeze glycoproteins has enabled notothenioid fish to flourish in the freezing waters of the Southern Ocean. Whereas successful at the biodiversity level to life in the cold, paradoxically at the cellular level these stenothermal animals have problems producing, folding, and degrading proteins at their ambient temperatures of -1.86 °C. In this first multi-species transcriptome comparison of the amino acid composition of notothenioid proteins with temperate teleost proteins, we show that, unlike psychrophilic bacteria, Antarctic fish provide little evidence for the mass alteration of protein amino acid composition to enhance protein folding and reduce protein denaturation in the cold. The exception was the significant overrepresentation of positions where leucine in temperate fish proteins was replaced by methionine in the notothenioid orthologues. We hypothesize that these extra methionines have been preferentially assimilated into the genome to act as redox sensors in the highly oxygenated waters of the Southern Ocean. This redox hypothesis is supported by analyses of notothenioids showing enrichment of genes associated with responses to environmental stress, particularly reactive oxygen species. So overall, although notothenioid fish show cold-associated problems with protein homeostasis, they may have modified only a selected number of biochemical pathways to work efficiently below 0 °C. Even a slight warming of the Southern Ocean might disrupt the critical functions of this handful of key pathways with considerable impacts for the functioning of this ecosystem in the future

An interaction abstraction model for seamless avatar exchange in CVET

International audienceCollaboration and interaction between users and virtual humans in virtual environments is a crucial challenge, notably for Collaborative Virtual Environments for Training (CVET). A training procedure, indeed, often involves several actors: trainees, teammates and many times a trainer. Yet, a major benefit of CVET is to propose to users to be trained even if the required number of person needed by the procedure is not available. Therefore, almost every CVET use autonomous virtual humans to replace the missing person. In this paper, we present the main results of our project that aims at improving the effective collaboration between users and virtual humans involved in a complex task within CVET. Using an entity called the "Shell", we are able to wrap the features common to both users and virtual humans. It gives us an abstraction level to pool the management of the main processes useful to control an avatar, interact with the environment and gather knowledge from a CVET. Besides, the Shell allows seamless exchange of avatars during a procedure. Thanks to the Shell, the exchange can be carried out at any time during a task while preserving all the data associated to a role in a procedure

Development and validation of an instrument to measure health-related out-of-pocket costs : the cost for patients questionnaire

Objective: The growth of healthcare spending is a major concern for insurers and governments but also for patients whose health problems may result in costs going beyond direct medical costs. To develop a comprehensive tool to measure direct and indirect costs of a health condition for patients and their families to various outpatient contexts. Methods: We conducted a content and face validation including results of a systematic review to identify the items related to direct and indirect costs for patients or their families and an online Delphi to determine the cost items to retain. We conducted a pilot test-retest with 18 naive participants and analyzed data calculating intraclass correlation and kappa coefficients. Results: An initial list of 34 items was established from the systematic review. Each round of the Delphi panel incorporated feedback from the previous round until a strong consensus was achieved. After 4 rounds of the Delphi to reach consensus on items to be included and wording, the questionnaire had a total of 32 cost items. For the test-retest, kappa coefficients ranged from 20.11 to 1.00 (median = 0.86), and intraclass correlation ranged from 20.02 to 0.99 (median = 0.62). Conclusions: A rigorous process of content and face development was implemented for the Cost for Patients Questionnaire, and this study allowed to set a list of cost elements to be considered from the patient's perspective. Additional research including a test-retest with a larger sample will be part of a subsequent validation strategy