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Comparison of Dynamical Heterogeneity in Hard-Sphere and Attractive Glass Formers †
No full textUsing molecular dynamics simulations, we have determined that the nature of dynamical heterogeneity in jammed liquids is very sensitive to short-ranged attractions. Weakly attractive systems differ little from dense hard-sphere and Lennard-Jones fluids. Particle motion is punctuated and tends to proceed in steps of roughly a single particle diameter. Both of these basic features change in the presence of appreciable short-ranged attractions. Transient periods of particle mobility and immobility cannot be discerned at intermediate attraction strength, for which structural relaxation is greatly enhanced. Strong attractions, known to dramatically inhibit relaxation, restore bimodality of particle motion. But in this regime, transiently mobile particles move in steps that are significantly more biased toward large displacements than those in the case of weak attractions. This modified feature of dynamical heterogeneity, which cannot be captured by conventional mode coupling theory, verifies recent predictions from a model of spatially correlated facilitating defects. Dynamical heterogeneity is perhaps the most revealing feature of relaxation in deeply supercooled liquids. A high-temperature fluid is dynamically homogeneous in the sense that the local environment restricting fluctuations of any given particle is, for all important purposes, identical to that surrounding any other particle, even on the short time scales of basic microscopic motions. The distribution P(δr,t) of particle displacements, δr, as a function of time t, provides a quantitative measure of such uniformity. Results of molecular dynamics simulations indicate that P(δr,t) is Gaussian over a wide range of displacements, as would be expected from a mean-field perspective, for typical dense fluids. 1 The microscopic environments constraining particle motion in a glassy material are by contrast profoundly nonuniform, even on the long time scales of large-wavelength relaxation
Responses of Metabolites in Soybean Shoot Apices to Changing Atmospheric Carbon Dioxide Concentrations
No full textSoybean seedlings were grown in controlled environment chambers with CO 2 partial pressures of 38 (ambient) and 72 (elevated) Pa. Five or six shoot apices were harvested from individual 21-to 24-day-old plants. Metabolites were analyzed by gas chromatography and, out of 21 compounds, only sucrose and fructose increased in response to CO 2 enrichment. One unidentified metabolite, Unk-21.03 decreased up to 80% in soybean apices in response to elevated CO 2 . Levels of Unk-21.03 decreased progressively when atmospheric CO 2 partial pressures were increased from 26 to 100 Pa. Reciprocal transfer experiments showed that Unk-21.03, and sucrose in soybean apices were altered slowly over several days to changes in atmospheric CO 2 partial pressures. The mass spectrum of Unk-21.03 indicated that this compound likely contained both an amino and carboxyl group and was structurally related to serine and aspartate. Our findings suggested that CO 2 enrichment altered a small number of specific metabolites in soybean apices. This could be an important step in understanding how plant growth and development are affected by carbon dioxide enrichment
Multitouch-based Annotation Boards for Face-to-Face Discussions
No full textABSTRACT This paper presents a hybrid approach to annotations for face-toface settings. Firstly, multitouch-based cooperative interaction for large displays is used to support group discussions with many different structures. Secondly, augmented notes are used to integrate paper-based notes in electronic structures
3D VISUALISATIONS IN SIMULATIONS OF FUTURE LAND USE: EXPLORING THE POSSIBILITIES OF NEW, STANDARD VISUALISATION TOOLS
No full textABSTRACT: Three-dimensional visualisations are an interesting method for representing model outcomes. But most visualisation techniques require expensive software, and a lot of time to create them. When a large set of visualisations is needed, or when the visualisations need to be adapted frequently, a faster and more flexible method is needed. The first step of the proposed model is to create the 3D elements. These elements are combined with the base map, and distributed to the public using Google Earth. Both freely available and commercial software are used in this process
Hierarchical Frequency Control Scheme for Islanded Multi-Microgrids Operation
No full textAbstract-This paper presents a new hierarchical approach to deal with the problem of controlling frequency and active power generation of a medium voltage network comprising several microgrids and distributed generation sources operated in islanded mode. The hierarchical approach described here should be cost effective and capable of dealing with large numbers of distributed microsources and performing tasks related to coordinated frequency control
Effects of Preparation Parameters on Characteristics of Cu-ZnO-Al 2 O 3 Catalysts for Low Pressure Methanol Synthesis
No full textAbstract Catalysts containing copper, zinc and aluminum are widely used in hydrogenation and some other petrochemical processes. Among the latter are low temperature water -gas shift conversion and methanol synthesis at low pressure. In this paper, by using a special three-level experimental design, the effects of certain preparation parameters on crystalline phase of the catalysts for calcined and uncalcined precursors are discussed. The influence of such parameters on total surface area, copper metal surface area and also on reactor activity of the catalysts are also investigated
Deformation of compact Clifford-Klein forms of indefinite-Riemannian homogeneous manifolds
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Handling heterogeneity for efficient implementations A case study on sequence comparison
No full textAbstract-The focus of this talk is to present and discuss scheduling strategies in the context of hybrid parallel multi-core platforms composed of multicores with accelerators (GPUs). We put emphasis on general purpose policies developed at the middleware level (by opposition to codes tuned by the expert users for specific applications). We survey several recent results in various situations (off-line/on-line scheduling, for both independent tasks and precedence relations). These results are illustrated by actual experiments on the comparison of biological sequences in large databases