Design of a 3 GHz Accelerator Structure for the CLIC Test Facility (CTF 3) Drive Beam

For the CLIC two-beam scheme, a high-current, long-pulse drive beam is required for RF power generation. Taking advantage of the 3 GHz klystrons available at the LEP injector once LEP stops, a 180 MeV electron accelerator is being constructed for a nominal beam current of 3.5 A and 1.5 microsecond pulse length. The high current requires highly effective suppression of dipolar wakes. Two concepts are investigated for the accelerating structure design: the "Tapered Damped Structure" developed for the CLIC main beam, and the "Slotted Iris - Constant Aperture" structure. Both use 4 SiC loads per cell for effective higher-order mode damping. A full-size prototype of the TDS structure has been built and tested successfully at full power. A first prototype of the SICA structure is being built.Comment: Contribution to Linac 2000 Conference, TUA16 (Poster

3D Hopkinson bar: new experiments for dynamic testing on soils.

International audienceThe direct analysis of the dynamic response of materials is possible using Split Hopkinson pressure bar method. For soils, it has to be adapted since the specimen has generally poor mechanical properties. An original experimental arrangement called "Three-Dimensional Split Hopkinson Pressure Bar" (3D SHPB) is proposed. It allows the measurement of the complete three-dimensional dynamic response of soils. Different types of confinement systems are used. The results on different loading paths are compared with other works on sand and clay. The analysis at grain-size level gives further elements on the comminution process

Modelling the Frequency‐Dependent Effective Excess Charge Density in Partially Saturated Porous Media

International audienceIn the context of seismoelectric and self-potential surveying, the effective excess charge density and the electrokinetic coupling coefficient are key parameters relating the measured electrical potential and the hydraulic characteristics of the explored porous media. In this work, we present a novel flux averaging approach that permits to estimate the frequency-dependent effective excess charge density in partially saturated porous media. For this, we conceptualize the porous medium as a partially saturated bundle of capillary tubes under oscillatory flux conditions. We account for the pore size distribution (PSD) to determine the capillary-pressure saturation relationship of the corresponding medium, which, in turn, permits to determine the pore scale saturation. We then solve the Navier-Stokes equations within the saturated capillaries and, by means of a flux-averaging procedure, obtain upscaled expressions for: (i) the effective excess charge density, (ii) the effective permeability, and (iii) the electrokinetic coupling coefficient, which are functions of the saturation and the probing frequency. We analyze and explain the characteristics of these functions for three different PSDs: fractal, lognormal, and double lognormal. It is shown that the PSD characteristics have a strong effect on the corresponding electrokinetic response. The proposed flux-averaging approach has an excellent capability for reproducing experimental measurements and models in the literature, which are otherwise based on well-known empirical relationships. The results of this work constitute a useful framework for the interpretation of electrokinetic signals in partially saturated media

UC-377 Litter Scramble: Encouraging conservation through play

Litter Scramble is a quick-play video gaming experience that delivers a nostalgic low-res combination of 2d assets in a 3d environment to produce an informative and entertaining session that will leave the player better informed on the impact that pollution and littering have on the natural world around us. Featuring a cast of simply animated 2d animals appropriate for a Georgia state park, the player will control a ranger through two different levels, each reflecting a different park environment, in a race against time and the animals to capture as much litter as possible. The development team was eager to turn hardware limitations presented by the required operating device and display system into advantages of our game, which we have done successfully. The gaming experience features simple and intuitive controls, sound effects, background music, and the chance at placing in the top ten scores

Meeting Design Characteristics and Attendee Perceptions of Staff/Team Meeting Quality

Meetings are a common tool in organizations and are used for a variety of purposes and implemented in a variety of ways. Despite the prevalence of meetings, surveys suggest that they are often unproductive and costly. The current study focused on how meetings are designed in hopes of providing practically and theoretically meaningful recommendations for improving meeting quality. A total of 18 design characteristics associated with staff/team meetings were identified and their relevance to perceptions of meeting quality was tested. Using an online panel-based respondent pool of working adults, 367 individuals participated in a survey that they completed within 48 hr of their most recent staff/team meeting. The results demonstrated that 9 of the design characteristics, spanning all 4 categories of design characteristics (i.e., temporal, physical, procedural, and attendee), significantly predicted perceptions of meeting quality. Furthermore, this study validated and greatly extended previous research showing that agenda use, meeting punctuality, facility quality, and meeting facilitator status relate to meeting quality. In addition, this study identified specific relationships to meeting quality for several facility quality characteristics, including lighting, meeting space, refreshments, and temperature, and expanded our knowledge of key characteristics by identifying agreement use and the number of attendees as important. Taken together, these findings suggest that effective meeting design warrants holistic attention to all meeting aspects. These results were robust across demographics, including organizational type, gender, and supervisory status. Implications for meeting design are discussed

Loss of histone macroH2A1 in hepatocellular carcinoma cells promotes paracrine-mediated chemoresistance and CD4+CD25+FoxP3+ regulatory T cells activation

Rationale: Loss of histone macroH2A1 induces appearance of cancer stem cells (CSCs)-like cells in hepatocellular carcinoma (HCC). How CSCs interact with the tumor microenvironment and the adaptive immune system is unclear. Methods: We screened aggressive human HCC for macroH2A1 and CD44 CSC marker expression. We also knocked down (KD) macroH2A1 in HCC cells, and performed integrated transcriptomic and secretomic analyses. Results: Human HCC showed low macroH2A1 and high CD44 expression compared to control tissues. MacroH2A1 KD CSC-like cells transferred paracrinally their chemoresistant properties to parental HCC cells. MacroH2A1 KD conditioned media transcriptionally reprogrammed parental HCC cells activated regulatory CD4+/CD25+/FoxP3+ T cells (Tregs). Conclusions: Loss of macroH2A1 in HCC cells drives cancer stem-cell propagation and evasion from immune surveillance