1,417 research outputs found

    Phase gratings for plasmon focusing

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    We report gratings structures realized for the creation of focused plasmons through noncollinear phasematching. The gratings are created on gold by focused ion beam milling and the plasmons were measured using phase sensitive photon scanning tunneling microscope (PSTM)

    Engineered plasmon focusing on functional gratings

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    We report on the engineering of plasmon propagation and focusing by dedicated curved gratings and noncollinear phasematching. Gratings were created on gold by focused ion beam milling and plasmons were measured using phase sensitive PSTM

    Micro and macro indicators of competition: comparison and relation with productivity change

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    This paper investigates competition in the Dutch manufacturing sector. We look at various indicators that have been used throughout the literature and relate these to productivity growth. Moreover, where possible, the indicators and productivity growth are calculated at both the firm and industry level. This enables us to investigate differences in competition and in its relation with productivity for both aggregation levels. Our results indicate that contemporaneous competition is associated with lower productivity, while lagged competition is positively associated with productivity. This finding is consistent between micro and macro, and robust over the various indicators and industries. The results are consistent with the idea that firms first experience negative effects of changes in competition and need time to adjust, while in the period after adjustment productivity rises again.competition, productivity change, growth accounts, Production Statistics, micro-macro

    Tangible cooperative gestures: Improving control and initiative in digital photo sharing

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    © 2015 by the authors. This paper focuses on co-present digital photo sharing on a notebook and investigates how this could be supported. While analyzing the current digital photo sharing situation we noticed that there was a high threshold for visitors to take control of the personal computer of the photo owner, resulting in inequity of participation. It was assumed that visitors would have the opportunity to interact with the notebook more freely if this threshold was lowered by distributing the user interface and creating a more public, instead of personal, interaction space. This, in turn, could make them feel more involved and in control during a session, creating a more enjoyable experience. To test these assumptions a design prototype was created that stimulates participants to use tangible artifacts for cooperative gestures, a promising direction for the future of HCI. The situation with the cooperative gestures was compared with the regular digital photo sharing situation, which makes use of a keyboard. In dyads, visitors felt more involved and in control in the design prototype cooperative gestures condition (especially during storytelling), resulting in a more enjoyable digital photo sharing experience

    A method for dense packing discovery

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    The problem of packing a system of particles as densely as possible is foundational in the field of discrete geometry and is a powerful model in the material and biological sciences. As packing problems retreat from the reach of solution by analytic constructions, the importance of an efficient numerical method for conducting \textit{de novo} (from-scratch) searches for dense packings becomes crucial. In this paper, we use the \textit{divide and concur} framework to develop a general search method for the solution of periodic constraint problems, and we apply it to the discovery of dense periodic packings. An important feature of the method is the integration of the unit cell parameters with the other packing variables in the definition of the configuration space. The method we present led to improvements in the densest-known tetrahedron packing which are reported in [arXiv:0910.5226]. Here, we use the method to reproduce the densest known lattice sphere packings and the best known lattice kissing arrangements in up to 14 and 11 dimensions respectively (the first such numerical evidence for their optimality in some of these dimensions). For non-spherical particles, we report a new dense packing of regular four-dimensional simplices with density ϕ=128/219≈0.5845\phi=128/219\approx0.5845 and with a similar structure to the densest known tetrahedron packing.Comment: 15 pages, 5 figure

    Diversity in disease course of Duchenne and Becker muscular dystrophy

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    In this thesis research is presented about the progressive muscle diseases Duchenne and Becker muscular dystrophy, two hereditary muscle diseases caused by a mutation in the gene coding for dystrophin, a protein involved in muscle membrane stability. The first part describes the disease course of both diseases. It evaluates the effect of developments in care of Duchenne patients, improving age at wheelchair dependence and survival. Data are presented about the relatively mild disease course of selected Becker patients with a mutation that would be the result of exon skipping in a Duchenne patient, illustrating the possible result of this therapeutic approach. The second part of this thesis focusses on research into factors involved in disease variability. Data are presented regarding the role of dystrophin quantity in disease severity in Becker patients, showing no linear relationship. Expression of several dystrophin associated proteins is shown not to influence disease course either. Contrarily, a single nucleotide polymorphism in the LTBP4 gene involved in fibrosis and muscle regeneration is shown to influence disease severity. Lastly, a disease severity scale for Becker patients is presented in this thesis, enabling a better comparison of individual patients for the purpose of scientific research.UBL - phd migration 201

    Chlamydia control activities in Europe: cross-sectional survey

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    Background: Chlamydia is the most commonly reported bacterial sexually transmitted infection in Europe. The objective of the Screening for Chlamydia in Europe (SCREen) project was to describe current and planned chlamydia control activities in Europe. Methods: The authors sent a questionnaire asking about different aspects of chlamydia epidemiology and control to public health and clinical experts in each country in 2007. The principles of sexually transmitted infection control were used to develop a typology comprising five categories of chlamydia control activities. Each country was assigned to a category, based on responses to the questionnaire. Results: Experts in 29 of 33 (88%) invited countries responded. Thirteen of 29 countries (45%) had no current chlamydia control activities. Six countries in this group stated that there were plans to introduce chlamydia screening programmes. There were five countries (17%) with case management guidelines only. Three countries (10%) also recommended case finding amongst partners of diagnosed chlamydia cases or people with another sexually transmitted infection. Six countries (21%) further specified groups of asymptomatic people eligible for opportunistic chlamydia testing. Two countries (7%) reported a chlamydia screening programme. There was no consistent association between the per capita gross domestic product of a country and the intensity of chlamydia control activities (P = 0.816). Conclusion: A newly developed classification system allowed the breadth of ongoing national chlamydia control activities to be described and categorized. Chlamydia control strategies should ensure that clinical guidelines to optimize chlamydia diagnosis and case management have been implemented before considering the appropriateness of screening programmes
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