Natural Virtual Reality User Interface to Define Assembly Sequences for Digital Human Models

Digital human models (DHMs) are virtual representations of human beings. They are used to conduct, among other things, ergonomic assessments in factory layout planning. DHM software tools are challenging in their use and thus require a high amount of training for engineers. In this paper, we present a virtual reality (VR) application that enables engineers to work with DHMs easily. Since VR systems with head-mounted displays (HMDs) are less expensive than CAVE systems, HMDs can be integrated more extensively into the product development process. Our application provides a reality-based interface and allows users to conduct an assembly task in VR and thus to manipulate the virtual scene with their real hands. These manipulations are used as input for the DHM to simulate, on that basis, human ergonomics. Therefore, we introduce a software and hardware architecture, the VATS (virtual action tracking system). This paper furthermore presents the results of a user study in which the VATS was compared to the existing WIMP (Windows, Icons, Menus and Pointer) interface. The results show that the VATS system enables users to conduct tasks in a significantly faster way

跨大西洋贸易与投资伙伴关系协定：一个建设性视角

欧盟与美国于 2013 年 7 月展开《跨大西洋贸易与投资伙伴关系协定》(TTIP)谈 判，这是两大贸易伙伴间达成全面经济协定的一项重要举措。正如往期《展望》 所指出的，该协定为贸易与投资自由化以及规制一致性提供了重大机遇。协定的高目标意味着高风险，尽管谈判各方在谈判初期持乐观态度，但协议能否达成尚未确定

The Transatlantic Trade and Investment Partnership: A critical perspective

Launched in July 2013 by the European Union and the United States, the Transatlantic Trade and Investment Partnership (TTIP) represents an important effort to reach a comprehensive economic agreement between two major trading partners. As has been pointed out, the project offers great opportunities for liberalizing trade and investment and regulatory convergence. Its level of ambition implies high risks, but despite negotiators’ initialoptimism, its success is far from certain

Sucrose- and H+-dependent charge movements associated with the gating of sucrose transporter ZmSUT1

Background: In contrast to man the majority of higher plants use sucrose as mobile carbohydrate. Accordingly proton-driven sucrose transporters are crucial for cell-to-cell and long-distance distribution within the plant body. Generally very negative plant membrane potentials and the ability to accumulate sucrose quantities of more than 1 M document that plants must have evolved transporters with unique structural and functional features. Methodology/Principal Findings: To unravel the functional properties of one specific high capacity plasma membrane sucrose transporter in detail, we expressed the sucrose/H+ co-transporter from maize ZmSUT1 in Xenopus oocytes. Application of sucrose in an acidic pH environment elicited inward proton currents. Interestingly the sucrose-dependent H+ transport was associated with a decrease in membrane capacitance (Cm). In addition to sucrose Cm was modulated by the membrane potential and external protons. In order to explore the molecular mechanism underlying these Cm changes, presteady-state currents (Ipre) of ZmSUT1 transport were analyzed. Decay of Ipre could be best fitted by double exponentials. When plotted against the voltage the charge Q, associated to Ipre, was dependent on sucrose and protons. The mathematical derivative of the charge Q versus voltage was well in line with the observed Cm changes. Based on these parameters a turnover rate of 500 molecules sucrose/s was calculated. In contrast to gating currents of voltage dependent-potassium channels the analysis of ZmSUT1-derived presteady-state currents in the absence of sucrose (I = Q/τ) was sufficient to predict ZmSUT1 transport-associated currents. Conclusions: Taken together our results indicate that in the absence of sucrose, ‘trapped’ protons move back and forth between an outer and an inner site within the transmembrane domains of ZmSUT1. This movement of protons in the electric field of the membrane gives rise to the presteady-state currents and in turn to Cm changes. Upon application of external sucrose, protons can pass the membrane turning presteady-state into transport currents

Rank Priors for Continuous Non-Linear Dimensionality Reduction

Non-linear dimensionality reduction methods are powerful techniques to deal with high-dimensional datasets. However, they often are susceptible to local minima and perform poorly when initialized far from the global optimum, even when the intrinsic dimensionality is known a priori. In this work we introduce a prior over the dimensionality of the latent space, and simultaneously optimize both the latent space and its intrinsic dimensionality. Ad-hoc initialization schemes are unnecessary with our approach; we initialize the latent space to the observation space and automatically infer the latent dimensionality using an optimization scheme that drops dimensions in a continuous fashion. We report results applying our prior to various tasks involving probabilistic non-linear dimensionality reduction, and show that our method can outperform graph-based dimensionality reduction techniques as well as previously suggested ad-hoc initialization strategies

Development and characterization of a catalyst for the decomposition of hydrogen peroxide

International audienceThe design of a reliable and effective catalytic bed with high and reproducible performance is one of the key steps during the development of a highly concentrated hydrogen peroxide thruster. The present paper focuses on the development and characterization of such a catalyst for the decomposition of hydrogen peroxide. A catalyst pre-screening performed by Heraeus on various precious metal-based catalysts supported on alumina granules showed that Pt is the most promising metal for the decomposition of H 2 O 2. Some further investigations were carried out to study the influence of various preparation parameters on the catalytic activity of the Pt catalysts. The prepared catalysts were characterized with various technics (transmission electron microscopy, X-ray diffraction, specific surface area) to better understand the impact of the studied preparation parameters on the catalyst activity for hydrogen peroxide decomposition. Finally, some monopropellant firing tests were performed by ONERA using the most promising catalysts and this paper presents some of the results obtained in their test facility