845 resultados para ordered metric-spaces


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Diffusion-ordered NMR spectroscopy ("DOSY") is a useful tool for the identification of mixture components. In its basic form it relies on simple differences in hydrodynamic radius to distinguish between different species. This can be very effective where species have significantly different molecular sizes, but generally fails for isomeric species. The use of surfactant co-solutes can allow isomeric species to be distinguished by virtue of their different degrees of interaction with micelles or reversed micelles. The use of micelle-assisted DOSY to resolve the NMR spectra of isomers is illustrated for the case of the three dihydroxybenzenes (catechol, resorcinol, and hydroquinone) in aqueous solution containing sodium dodecyl sulfate micelles, and in chloroform solution containing AOT reversed micelles. © 2009 American Chemical Society.

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Appealingly simple: A new method is described that allows the diffusion coefficient of a small molecule to be estimated given only the molecular weight and the viscosity of the solvent used. This method makes possible the quantitative interpretation of the diffusion domain of diffusion-ordered NMR spectra (see picture). © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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An alkali- and nitrate-free hydrotalcite coating has been grafted onto the surface of a hierarchically ordered macroporous-mesoporous SBA-15 template via stepwise growth of conformal alumina adlayers and their subsequent reaction with magnesium methoxide. The resulting low dimensional hydrotalcite crystallites exhibit excellent per site activity for the base catalysed transesterification of glyceryl triolein with methanol for FAME production.

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Incorporating further information into the ordered weighted averaging (OWA) operator weights is investigated in this paper. We first prove that for a constant orness the minimax disparity model [13] has unique optimal solution while the modified minimax disparity model [16] has alternative optimal OWA weights. Multiple optimal solutions in modified minimax disparity model provide us opportunity to define a parametric aggregation OWA which gives flexibility to decision makers in the process of aggregation and selecting the best alternative. Finally, the usefulness of the proposed parametric aggregation method is illustrated with an application in metasearch engine. © 2011 Elsevier Inc. All rights reserved.

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The article explores the possibilities of formalizing and explaining the mechanisms that support spatial and social perspective alignment sustained over the duration of a social interaction. The basic proposed principle is that in social contexts the mechanisms for sensorimotor transformations and multisensory integration (learn to) incorporate information relative to the other actor(s), similar to the "re-calibration" of visual receptive fields in response to repeated tool use. This process aligns or merges the co-actors' spatial representations and creates a "Shared Action Space" (SAS) supporting key computations of social interactions and joint actions; for example, the remapping between the coordinate systems and frames of reference of the co-actors, including perspective taking, the sensorimotor transformations required for lifting jointly an object, and the predictions of the sensory effects of such joint action. The social re-calibration is proposed to be based on common basis function maps (BFMs) and could constitute an optimal solution to sensorimotor transformation and multisensory integration in joint action or more in general social interaction contexts. However, certain situations such as discrepant postural and viewpoint alignment and associated differences in perspectives between the co-actors could constrain the process quite differently. We discuss how alignment is achieved in the first place, and how it is maintained over time, providing a taxonomy of various forms and mechanisms of space alignment and overlap based, for instance, on automaticity vs. control of the transformations between the two agents. Finally, we discuss the link between low-level mechanisms for the sharing of space and high-level mechanisms for the sharing of cognitive representations. © 2013 Pezzulo, Iodice, Ferraina and Kessler.

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Highly ordered mesoporous alumina was prepared via evaporation induced self assembly and was impregnated to afford a family of Pd/meso-Al2O3 catalysts for the aerobic selective oxidation (selox) of allylic alcohols under mild reaction conditions. CO chemisorption and XPS identify the presence of highly dispersed (0.9–2 nm) nanoparticles comprising heavily oxidised PdO surfaces, evidencing a strong palladium-alumina interaction. Surface PdO is confirmed as the catalytically active phase responsible for allylic alcohol selox, with initial rates for Pd/meso-Al2O3 far exceeding those achievable for palladium over either amorphous alumina or mesoporous silica supports. Pd/meso-Al2O3 is exceptionally active for the atom efficient selox of diverse allylic alcohols, with activity inversely proportional to alcohol mass.

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The utility of a hierarchically ordered nanoporous SBA-15 architecture, comprising 270 nm macropores and 5 nm mesopores (MM-SBA-15), for the catalytic aerobic selective oxidation of sterically challenging allylic alcohols is shown. Detailed bulk and surface characterization reveals that incorporation of complementary macropores into mesoporous SBA-15 enhances the dispersion of sub 2 nm Pd nanoparticles and thus their degree of surface oxidation. Kinetic profiling reveals a relationship between nanoparticle dispersion and oxidation rate, identifying surface PdO as the catalytically active phase. Hierarchical nanoporous Pd/MM-SBA-15 outperforms mesoporous analogues in allylic alcohol selective oxidation by (i) stabilizing PdO nanoparticles and (ii) dramatically improving in-pore diffusion and access to active sites by sesquiterpenoid substrates such as farnesol and phytol. © 2013 American Chemical Society.

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Four experiments with unfamiliar objects examined the remarkably late consolidation of part-relational relative to part-based object recognition (Jüttner, Wakui, Petters, Kaur, & Davidoff, 2013). Our results indicate a particularly protracted developmental trajectory for the processing of metric part relations. Schoolchildren aged 7 to 14 years and adults were tested in 3-Alternative-Forced-Choice tasks to judge the correct appearance of upright and inverted newly learned multipart objects that had been manipulated in terms of individual parts or part relations. Experiment 1 showed that even the youngest tested children were close to adult levels of performance for recognizing categorical changes of individual parts and relative part position. By contrast, Experiment 2 demonstrated that performance for detecting metric changes of relative part position was distinctly reduced in young children compared with recognizing metric changes of individual parts, and did not approach the latter until 11 to 12 years. A similar developmental dissociation was observed in Experiment 3, which contrasted the detection of metric relative-size changes and metric part changes. Experiment 4 showed that manipulations of metric size that were perceived as part (rather than part-relational) changes eliminated this dissociation. Implications for theories of object recognition and similarities to the development of face perception are discussed. © 2014 American Psychological Association.

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Purpose: This paper aims to report on a project undertaken in order to identify, develop and reflect on the leadership and managerial skills of clinicians. The main aim of the project was to design, plan, organise and deliver a learning session for Foundation Year 2 Doctors within the premises of one of the largest NHS Foundation Trusts in the UK. The key theme of the learning session was the introduction of the notion of competent medical leadership in the NHS. A leadership role has been traditionally seen as the task of managers and as such clinicians have seemed reluctant to engage. Design/methodology/approach: A two hour workshop was designed and delivered with the use of Open Space Technology. Foundation Year 2 doctors were invited to consider the importance of leadership in their everyday roles. An awareness of the Medical Leadership Competency Framework had been a key aspect of the learning session. Findings: The project's outcome can be identified as being the encouragement of Foundation Year 2 doctors in considering their roles as leaders in their everyday tasks. Originality/value: Design, planning, organisation and delivery of a two hour Open Space learning session with the Foundation Year 2 doctors portrays the session's learning potentials and the potential for such sessions to provide a platform for difficult discussions in the NHS. This is particularly beneficial where a cultural shift is needed in order to see a way forward, notably when facing significant change. © Emerald Group Publishing Limited.

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In this paper, we address the problem of robust information embedding in digital data. Such a process is carried out by introducing modifications to the original data that one would like to keep minimal. It assumes that the data, which includes the embedded information, is corrupted before the extraction is carried out. We propose a principled way to tailor an efficient embedding process for given data and noise statistics. © Springer-Verlag Berlin Heidelberg 2005.

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Many people think of language as words. Words are small, convenient units, especially in written English, where they are separated by spaces. Dictionaries seem to reinforce this idea, because entries are arranged as a list of alphabetically-ordered words. Traditionally, linguists and teachers focused on grammar and treated words as self-contained units of meaning, which fill the available grammatical slots in a sentence. More recently, attention has shifted from grammar to lexis, and from words to chunks. Dictionary headwords are convenient points of access for the user, but modern dictionary entries usually deal with chunks, because meanings often do not arise from individual words, but from the chunks in which the words occur. Corpus research confirms that native speakers of a language actually work with larger “chunks” of language. This paper will show that teachers and learners will benefit from treating language as chunks rather than words.

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Indentation of ceramic materials with smooth indenters such as parabolae of revolution and spheres can be conducted in the elastic regime to relatively high loads. Ceramic single crystals thus provide excellent calibration media for load-and depth-sensing indentation testing; however, they are generally anisotropic and a complete elastic analysis is cumbersome. This study presents a simplified procedure for the determination of the stiffness of contact for the indentation of an anisotropic half-space by a rigid frictionless parabola of revolution which, to first order, approximates spherical indentation. Using a similar approach, a new procedure is developed for analysing conical indentation of anisotropic elastic media. For both indenter shapes, the contact is found to be elliptical, and equations are determined for the size, shape and orientation of the ellipse and the indentation modulus.

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In this paper we take seriously the call for strategy-as-practice research to address the material, spatial and bodily aspects of strategic work. Drawing on a video-ethnographic study of strategic episodes in a financial trading context, we develop a conceptual framework that elaborates on strategic work as socially accomplished within particular spaces that are constructed through different orchestrations of material, bodily and discursive resources. Building on the findings, our study identifies three types of strategic work - private work, collaborative work and negotiating work - that are accomplished within three distinct spaces that are constructed through multimodal constellations of semiotic resources. We show that these spaces, and the activities performed within them, are continuously shifting in ways that enable and constrain the particular outcomes of a strategic episode. Our framework contributes to the strategy-as-practice literature by identifying the importance of spaces in conducting strategic work and providing insight into the way that these spaces are constructed.

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The concept of data independence designates the techniques that allow data to be changed without affecting the applications that process it. The different structures of the information bases require corresponded tools for supporting data independence. A kind of information bases (the Multi-dimensional Numbered Information Spaces) are pointed in the paper. The data independence in such information bases is discussed.

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The paper discusses the application of a similarity metric based on compression to the measurement of the distance among Bulgarian dia- lects. The similarity metric is de ned on the basis of the notion of Kolmo- gorov complexity of a le (or binary string). The application of Kolmogorov complexity in practice is not possible because its calculation over a le is an undecidable problem. Thus, the actual similarity metric is based on a real life compressor which only approximates the Kolmogorov complexity. To use the metric for distance measurement of Bulgarian dialects we rst represent the dialectological data in such a way that the metric is applicable. We propose two such representations which are compared to a baseline distance between dialects. Then we conclude the paper with an outline of our future work.