44,786 research outputs found
Fabrication of waveguides and microfluidic channels in fused silica by a femtosecond laser
No full textFabrication of optical waveguides in glasses and crystals is very common for many applications in integrated optics. They are commonly fabricated by ionic exchange or diffu- sion into a transparent substrate, by laser irradiation of spe- cial photorefractive materials, or by lithographic methods. Although these technologies are well established and successful they are not very flexible in terms of geometry that can be obtained especially when three-dimensional photonic devices are required. To overcome this limitation, femtosecond lasers could offer a valid alternative to tradi- tional technologies due to the recent development of high energy density laser sources, which would allow infrared laser to interact with glass substrate as shown in. In this article, it was pointed out, for the first time, that a tightly focussed femtosecond laser can be absorbed inside a bulk glass, giving the opportunity to develop new tech- nologies in optical devices fabrications. Since then, several research groups have reported their results in fabricating many devices, in many materials, using many different laser configurations and parameters
MODELLING TECHNICAL EFFICIENCY IN CROSS SECTIONALLY DEPENDENT STOCHASTIC FRONTIER PANELS
No full textThis paper proposes a unified framework for accommodating both time and cross-sectional dependence in
modelling technical efficiency in stochastic frontier models by combining the exogenously driven factor-based
approach and an endogenous threshold efficiency regime selection mechanism. This approach is able to deal with
both weak and strong cross-sectional dependence in a flexible manner. Using a dataset of 26 OECD countries over
1970–2010, we provide satisfactory estimation results for the production technology parameters and the associated
efficiency ranking of individual countries. We find a positive spillover effect on efficiency, supporting the
hypothesis that knowledge spillover is more likely to be induced by technological proximity. Furthermore, our
approach enables us to identify efficiency clubs endogenously
The role of sirtuin 1 in osteoblastic differentiation in human periodontal ligament cells
No full textBackground and Objective: Activation of sirtuin 1 (SIRT1) promotes the differentiation of keratinocytes and mesenchymal stem cells, but inhibits the differentiation of muscle and fat cells. However, the involvement of SIRT1 in the differentiation of human periodontal ligament cells into osteoblast-like cells remains unclear. To identify the role of SIRT1 in human periodontal ligament cells, we measured SIRT1 mRNA and SIRT1 protein levels during the osteoblastic differentiation of human periodontal ligament cells. Additionally, we investigated the effects of overexpressing and underexpressing SIRT1 on the differentiation of human periodontal ligament cells, and the signaling mechanisms involved. Material and Methods: Expression of SIRT1 and osteoblastic differentiation markers was assessed by RT-PCR, real-time PCR, Alizarin red staining and western blotting. Results: Marked upregulation of SIRT1 mRNA and SIRT1 protein was observed in cells grown for 3 d in osteogenic induction medium (OM). Activation of SIRT1 using resveratrol and isonicotinamide stimulated osteoblastic differentiation in a dose-dependent manner, as assessed by the expression of mRNAs encoding alkaline phosphatase, osteopontin, osteocalcin, osterix and Runx2, and induced calcium deposition. In contrast, inhibition of SIRT1 using sirtinol, nicotinamide and gene silencing by RNA interference suppressed mineralization and the expression of osteoblast marker mRNAs. Further mechanistic studies revealed that resveratrol treatment increased the phosphorylation of Akt, adenosine monophosphate kinase (AMPK), Smad 1/5/8 and c-Jun N-terminal kinase, but reduced OM-induced activation of nuclear factor-kappa B. Conversely, application of sirtinol suppressed the phosphorylation of Akt, AMPK, Smad 1/5/8, p38, ERK and c-Jun N-terminal kinase, and enhanced nuclear factor-jB activity, in OM-stimulated cells. Conclusion: These data suggest that SIRT1 is a potent regulator of differentiation of human periodontal ligament cells and may have clinical implications for periodontal bone regeneration.
Globalisation and technological convergence in the EU
No full textWe employ a two-step approach in investigating the dynamic transmission channels under which globalization factors foster technical efficiency by combining a
dynamic efficiency analysis in the stochastic frontier
framework, and a time series approach based on VAR and
spectral analysis. Using the dataset of the 18 EU countries
over 1970–2004, we find that both import and FDI are
significant factors in spreading efficiency externalities and
thus accelerating technology catch-up in the EU. In particular, the impacts of the import are more prominent in the
short-run while those of FDI play a more important role
over the longer-run. Furthermore, the impacts of the import
are pro-cyclical only in the short-run whereas those of FDI
are pro-cyclical mostly over the medium- to the long-run.
This evidence is broadly consistent with the sample
observation that the recent slowdown of the EU productivity has been closely related to the corresponding FDI
decline especially after 2000. Hence, any protection-oriented policy will be likely to be more detrimental for the
EU
Discrimination between earthquake and noise signals on strong motion records by artificial neural networks
No full textNear Realtime Mapping of Peak Ground Acceleration and Peak Ground Velocity following a Strong Earthquake
No full textUSING DISTRIBUTED BRILLOUIN FIBER SENSOR TO DETECT THE STRAIN AND CRACKS OF STEEL STRUCTURES
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