Interaction between nearby strangers: serendipity and playfulness

“Nearby strangers” provides an interestingly paradoxical space for interaction design. There are various social norms, cultural practices, and privacy concerns hindering interaction with nearby strangers, but by ignoring them, people constantly miss social opportunities. Technology enabling ad-hoc interactions between co-located people has been explored for years in research but real-life applications are still rare. The potential focus areas include increasing awareness of social possibilities; light-weight playful interactions, play and gaming; serendipitous and ad hoc social interaction; anonymous exchange of content; matching interests for various purposes; icebreakers and provocation to interact, and ambient representation of the nearby strangers. This workshop convenes researchers and practitioners to gather and advance the state of research on interactions between nearby strangers. We aim to explore this design space and collaboratively identify new research and design opportunities that novel communication technology creates

Responses to hydric stress in the seed-borne necrotrophic fungus Alternaria brassicicola

Alternaria brassicicola is a necrotrophic fungus causing black spot disease and is an economically important seed-borne pathogen of cultivated brassicas. Seed transmission is a crucial component of its parasitic cycle as it promotes long-term survival and dispersal. Recent studies, conducted with the Arabidopsis thaliana/A. brassicicola pathosystem, showed that the level of susceptibility of the fungus to water stress strongly influenced its seed transmission ability. In this study, we gained further insights into the mechanisms involved in the seed infection process by analyzing the transcriptomic and metabolomic responses of germinated spores of A. brassicicola exposed to water stress. Then, the repertoire of putative hydrophilins, a group of proteins that are assumed to be involved in cellular dehydration tolerance, was established in A. brassicicola based on the expression data and additional structural and biochemical criteria. Phenotyping of single deletion mutants deficient for fungal hydrophilin-like proteins showed that they were affected in their transmission to A. thaliana seeds, although their aggressiveness on host vegetative tissues remained intact

Transcriptional Control of Steroid Biosynthesis Genes in the Drosophila Prothoracic Gland by Ventral Veins Lacking and Knirps.

Specialized endocrine cells produce and release steroid hormones that govern development, metabolism and reproduction. In order to synthesize steroids, all the genes in the biosynthetic pathway must be coordinately turned on in steroidogenic cells. In Drosophila, the steroid producing endocrine cells are located in the prothoracic gland (PG) that releases the steroid hormone ecdysone. The transcriptional regulatory network that specifies the unique PG specific expression pattern of the ecdysone biosynthetic genes remains unknown. Here, we show that two transcription factors, the POU-domain Ventral veins lacking (Vvl) and the nuclear receptor Knirps (Kni), have essential roles in the PG during larval development. Vvl is highly expressed in the PG during embryogenesis and is enriched in the gland during larval development, suggesting that Vvl might function as a master transcriptional regulator in this tissue. Vvl and Kni bind to PG specific cis-regulatory elements that are required for expression of the ecdysone biosynthetic genes. Knock down of either vvl or kni in the PG results in a larval developmental arrest due to failure in ecdysone production. Furthermore, Vvl and Kni are also required for maintenance of TOR/S6K and prothoracicotropic hormone (PTTH) signaling in the PG, two major pathways that control ecdysone biosynthesis and PG cell growth. We also show that the transcriptional regulator, Molting defective (Mld), controls early biosynthetic pathway steps. Our data show that Vvl and Kni directly regulate ecdysone biosynthesis by transcriptional control of biosynthetic gene expression and indirectly by affecting PTTH and TOR/S6K signaling. This provides new insight into the regulatory network of transcription factors involved in the coordinated regulation of steroidogenic cell specific transcription, and identifies a new function of Vvl and Knirps in endocrine cells during post-embryonic development

Experimental and analytical investigations on aerosol washout in a large vessel with high spray coverage ratio simulating PWR containment spray

International audienceIn severe accident scenarios of a PWR, containment spray can be employed to washout the aerosol of radioactive materials, retaining them in the containment. Therefore, it is crucial to correctly predict the aerosol washout efficiency for safety assessment. For a PWR containment, a high spray coverage ratio (>84%–95%) is required. However, experimental studies focusing on the washout efficiency with such a high coverage ratio in a large vessel are quite limited. To understand such a washout phenomenon toward model development, specifically for PWR, aerosol washout experiments are performed in a large vessel with not only aerosol measurements but also spray droplet characterizations. Significant droplet impaction on the vessel sidewall is observed, and the spray coverage ratios are experimentally confirmed to be compatible with a real PWR. The washout features are investigated in terms of individual particle diameters and the entire one. The model in the safety analysis code, MELCOR, is examined using the experimentally obtained aerosol removal rate, showing the removal rate tendency against particle diameters being reproduced. Although a significant underestimation occurs for large particles, a satisfactory agreement is obtained for smaller ones (<0.52 μm in diameter) corresponding to the minimum removal rate and around

Development and validation of agglomeration model for CFD simulations of aerosol dispersion during Fukushima fuel debris retrieval

International audienceThe general context of this article is related to demonstrate the feasibility of the use of the laser cutting technique for the fuel debris retrieval on the damaged reactors of Fukushima Dai-ichi. IRSN is involved in a project led by ONET, in collaboration with CEA, to bring relevant elements to analyze the risk occurred by the dispersion of aerosols emitted by the dismantling operations. During the laser cutting operations for retrieving the fuel debris in air condition, particles will be produced, inducing a potential risk of dispersion into the environment. Hence, evaluating the amount of aerosols able to deposit on the walls and those able to be released into the environment is one of the safety key issues in the dismantling actions of reactors of Fukushima Dai-ichi. For that, IRSN performed computational fluid dynamics (CFD) simulations of dispersion, agglomeration and deposition of particles whose size distribution was measured during laser cutting operations of inactive fuel simulants (Chagnot et al., 2018, Porcheron et al., 2018).These simulations were conducted with the ANSYS CFX CFD code into which a moment method called DQMOM and a deposition model previously developed by IRSN (Nerisson et al., 2011) were implemented. The first numerical results (Gelain et al., 2018) showed a quite good agreement with the experimental ones for a standard particle size distribution (lognormal with one mode), but some improvements are needed for less classical distributions such bimodal ones.The work presented here proposes an alternative method to the previous one allowing taking into account different kinds of particle size distribution in the CFD simulations of particle agglomeration. This method uses the real experimental distribution to calculate the distribution moments which are then directly implemented in the simulation instead of using a lognormal fit. The previous CFD simulations were calculated again by using this method and showed a better agreement with the experimental results issued from aerosol source term characterization for both absolute values and time evolutions

Development and validation of agglomeration model for CFD simulations of aerosol dispersion during Fukushima fuel debris retrieval

International audienceThe general context of this article is related to demonstrate the feasibility of the use of the laser cutting technique for the fuel debris retrieval on the damaged reactors of Fukushima Dai-ichi. IRSN is involved in a project led by ONET, in collaboration with CEA, to bring relevant elements to analyze the risk occurred by the dispersion of aerosols emitted by the dismantling operations. During the laser cutting operations for retrieving the fuel debris in air condition, particles will be produced, inducing a potential risk of dispersion into the environment. Hence, evaluating the amount of aerosols able to deposit on the walls and those able to be released into the environment is one of the safety key issues in the dismantling actions of reactors of Fukushima Dai-ichi. For that, IRSN performed computational fluid dynamics (CFD) simulations of dispersion, agglomeration and deposition of particles whose size distribution was measured during laser cutting operations of inactive fuel simulants (Chagnot et al., 2018, Porcheron et al., 2018).These simulations were conducted with the ANSYS CFX CFD code into which a moment method called DQMOM and a deposition model previously developed by IRSN (Nerisson et al., 2011) were implemented. The first numerical results (Gelain et al., 2018) showed a quite good agreement with the experimental ones for a standard particle size distribution (lognormal with one mode), but some improvements are needed for less classical distributions such bimodal ones.The work presented here proposes an alternative method to the previous one allowing taking into account different kinds of particle size distribution in the CFD simulations of particle agglomeration. This method uses the real experimental distribution to calculate the distribution moments which are then directly implemented in the simulation instead of using a lognormal fit. The previous CFD simulations were calculated again by using this method and showed a better agreement with the experimental results issued from aerosol source term characterization for both absolute values and time evolutions

Effect of vessel size scale on the aerosol spray scavenging efficiency with water mist

International audienceResearch interest in eliminating airborne aerosol particles has been growing for decades. Aerosol particles with aerodynamic diameters between 0.2 and 1 μm are difficult to remove by traditional spray systems. To improve the aerosol scavenging efficiency, a new method is proposed that employs the addition of water mist. Water mist is supposed to aggregate with aerosol particles to form large-sized coagulated aerosol-mist particle clusters, which can subsequently be removed by spray droplets with a higher efficiency. To investigate the effect of the vessel's size scale on the aerosol collection efficiency, aerosol spray scavenging experiments without and with water mist were conducted in both the UTARTS facility and TOSQAN facility. The cylindrical vessels of the two facilities have the same internal diameter, but the vessel of the TOSQAN facility has a larger height. Experimental results show that water mist has the potential to improve aerosol scavenging efficiency in both facilities but to a higher degree inside the TOSQAN facility. Numerical simulations of aerosol removal by spray droplets without mist were conducted, and different scaling criteria for the geometry of the vessel and gaseous entrainment rate were discussed to explain the experimental results. With water mist, the coagulated aerosol-mist particles have a stronger inertia and a larger Stokes number; these particles are easier to capture by using spray droplets and a water film. The contribution of the spray injection height, spray spread volume, and water film to aerosol removal in cases with mist increased to a larger degree than that of the gaseous entrainment rate, finally resulting in a higher improvement ratio of aerosol removal efficiency in the TOSQAN facility

Development and validation of an agglomeration model for CFD simulations of aerosol dispersion in the frame of Fukushima fuel debris retrieval

This article is devoted to demonstrate the feasibility of laser cutting technique for the fuel debris retrieval into the Fukushima Daiichi damaged reactors. IRSN is involved in a project led by ONET Technologies, in collaboration with CEA, to evaluate the risk occurred by the dispersion of aerosols emitted by the dismantling operations [4]. During the laser cutting operations of fuel debris in air condition, particles will be produced, inducing a potential risk of dispersion into the environment. Hence, evaluating the fate of these particles after their emission is one of the safety key issues for these dismantling operations. In this objective, IRSN performed CFD simulations of dispersion of particles representative of inactive fuel debris simulants (1)(2)(3)(4). The first numerical results (5) showed a quite good agreement but some improvements were needed to take into account complex particle size distributions (PSD). Consequently, this article proposes an alternative method to better initialize the agglomeration calculation, in order to take account for different kinds of particle size distribution in the CFD simulations and to better evaluate the fate of aerosols produced by the debris cutting in the damaged reactors of Fukushima-Daiichi pedestal

CHARACTERIZATION OF INCANDESCENT PARTICLES EMITTED BY A CUT-OFF GRINDER DURING DECOMMISSIONING OPERATIONS FOR EVALUATING FILTERS DEGRADATION

WOS:000367118300068International audienceThe use of mechanical or thermal cutting tools in decommissioning of nuclear facilities generates a lot of incandescent particles. Those particles may represent a deterioration risk of the containment barriers associated with a potential risk of fire starting. The aim of this study is to characterize the incandescent particles emitted by a wheel grinder (in terms of temperature, diameter and velocity) and to follow those parameters all along their path from their emission point to their impact on the air filter. The characteristics of particles correlated with a possible loss of filter efficiency should highlight the destructing particles for the filter. All the measurement techniques used to characterize experimentally the incandescent particles are presented in this article. Particles are characterized in terms of diameter by microscope visualizations. The particle velocity is measured with a high speed camera using Particle Tracking Velocimetry (PTV) technique. An adaptation of a commercial monochromatic pyrometer is achieved to measure the in-flight particles temperature in our specific configuration. All of these techniques have been implemented on an experimental facility which reproduces representative conditions of the cutting processes realized during dismantling operations. Concerning the investigation of the filter, a global and a local approaches about filter degradation are used. The decontamination factor of High Efficiency Particle Air (HEPA) filter is measured, and detailed visualizations of the filter fibers deteriorations are obtained using Scanning Electrons Microscope (SEM)

Characterization of Incandescent Particles Emitted by a Cut-Off Grinder During Decommissioning Operations for Evaluating Filter Degradation

International audienc