1,154 research outputs found
Sub-wavelength scale characterization of on-chip coupling mirrors
Miniature free-space optical beams, originating from on-chip microstructures, are usually measured and quoted without reference to a particular polarization state. We develop an automated platform to characterize tightly focused free-space optical beams in three dimensions. We present a detailed description of each subsystem including the calibration and test procedure. We demonstrate how amplitude and phase are measured at sub-wavelength resolution using a cleaved fiber with a heterodyne reference. Further analysis provides information about the phase and intensity profile of the beam with regards to its polarization content and spatial confinement. We perform a proof-of-concept experiment for a custom waveguide-coupled micro-mirror. The work opens new possibilities for rapid analysis of micro-mirrors in prototyping and optimization of integrated optical systems.</p
Angiotensin II induces TIMP-1 production in rat heart endothelial cells
AbstractAngiotensin II (AII) was found to upregulate tissue inhibitor of metalloproteineses-1 (TIMP-1) gene expression in rat heart endothelial cells in a dose and time-dependent manner. The maximal stimulation of TIMP-1 mRNA was achieved by 2 h after the addition of AII. This effect was blocked by losartan, an AT1 receptor antagonist and by calphostin C, a protein kinase C inhibitor. Addition of cycloheximide superinduced and actinomycin D abolished the induction. These results suggest that AII stimulates TIMP-1 production by a protein kinase C dependent pathway which is dependent upon de novo RNA synthesis. Immunoprecipitation experiment showed an enhanced band of 28 kDa from the conditioned medium of AII-treated cultures. Immunoblot analysis revealed that TIMP-1 was detectable in the conditioned medium 4 h after AII stimulation. Since endothelial cells line the blood vessels and sense the rise in AII associated with hypertension, the TIMP-1 released by these cells may provide an initial trigger leading to cardiac fibrosis in angiotensin-renin dependent hypertension
Management based on exhaled nitric oxidelevels adjusted for atopy reduces asthma exacerbations in children : A dual centre randomised controlled trial
While several randomised control trials (RCTs) have evaluated the use of fractional exhaled nitric oxide (FeNO) to improve asthma outcomes, none used FeNO cut-offs adjusted for atopy, a determinant of FeNO levels. In a dual centre RCT, we assessed whether a treatment strategy based on FeNO levels, adjusted for atopy, reduces asthma exacerbations compared with the symptoms-based management (controls).
Children with asthma from hospital clinics of two hospitals were randomly allocated to receive an a-priori determined treatment hierarchy based on symptoms or FeNO levels. There was a 2-week run-in period and they were then reviewed ten times over 12-months. The primary outcome was the number of children with exacerbations over 12-months.
Sixty-three children were randomised (FeNO=31, controls=32); 55 (86%) completed the study. Although we did achieve our planned sample size, significantly fewer children in the FeNO group (6 of 27) had an asthma exacerbation compared to controls (15 of 28), p=0.021; number to treat for benefit=4 (95%CI 3-24). There was no difference between groups for any secondary outcomes (quality of life, symptoms, FEV1). The final daily inhaled corticosteroids (ICS) dose was significantly (p=0.037) higher in the FeNO group (median 400µg, IQR 250-600) compared to the controls (200, IQR100-400).
Taking atopy into account when using FeNO to tailor asthma medications is likely beneficial in reducing the number of children with severe exacerbations at the expense of increased ICS use. However, the strategy is unlikely beneficial for improving asthma control. A larger study is required to confirm or refute our findings
Transport of Surface States in the Bulk Quantum Hall Effect
The two-dimensional surface of a coupled multilayer integer quantum Hall
system consists of an anisotropic chiral metal. This unusual metal is
characterized by ballistic motion transverse and diffusive motion parallel
(\hat{z}) to the magnetic field. Employing a network model, we calculate
numerically the phase coherent two-terminal z-axis conductance and its
mesoscopic fluctuations. Quasi-1d localization effects are evident in the limit
of many layers. We consider the role of inelastic de-phasing effects in
modifying the transport of the chiral surface sheath, discussing their
importance in the recent experiments of Druist et al.Comment: 9 pages LaTex, 9 postscript figures included using eps
Revisiting the -Meson Production at the Hadronic Colliders
The production of heavy-flavored hadron at the hadronic colliders provides a
challenging opportunity to test the validity of pQCD predictions. There are two
mechanisms for the hadroproduction, i.e. the gluon-gluon fusion
mechanism via the subprocess and the
extrinsic heavy quark mechanism via the subprocesses and , both of which shall have sizable
contributions in proper kinematic region. Different from the
fixed-flavor-number scheme (FFNS) previously adopted in the literature, we
study the hadroproduction under the general-mass
variable-flavor-number scheme (GM-VFNS), in which we can consistently deal with
the double counting problem from the above two mechanisms. Properties for the
hadroproduction are discussed. To be useful reference, a
comparative study of FFNS and GM-VFNS is presented. Both of which can provide
reasonable estimations for the hadroproduction. At the Tevatron,
the difference between these two schemes is small, however such difference is
obvious at the LHC. The forthcoming more precise data on LHC shall provide a
good chance to check which scheme is more appropriate to deal with the
-meson production and to further study the heavy quark components in
hadrons.Comment: 18 pages, 8 figures, 4 tables. To match the published version. To be
published in Eur.Phys.J.
Organic film thickness influence on the bias stress instability in Sexithiophene Field Effect Transistors
In this paper, the dynamics of bias stress phenomenon in Sexithiophene (T6)
Field Effect Transistors (FETs) has been investigated. T6 FETs have been
fabricated by vacuum depositing films with thickness from 10 nm to 130 nm on
Si/SiO2 substrates. After the T6 film structural analysis by X-Ray diffraction
and the FET electrical investigation focused on carrier mobility evaluation,
bias stress instability parameters have been estimated and discussed in the
context of existing models. By increasing the film thickness, a clear
correlation between the stress parameters and the structural properties of the
organic layer has been highlighted. Conversely, the mobility values result
almost thickness independent
Flexible active compensation based on load conformity factors applied to non-sinusoidal and asymmetrical voltage conditions
This study proposes a flexible active power filter (APF) controller operating selectively to satisfy a set of desired load performance indices defined at the source side. The definition of such indices, and of the corresponding current references, is based on the orthogonal instantaneous current decomposition and conformity factors provided by the conservative power theory. This flexible approach can be applied to single- or three-phase APFs or other grid-tied converters, as those interfacing distributed generators in smart grids. The current controller is based on a modified hybrid P-type iterative learning controller which has shown good steady-state and dynamic performances. To validate the proposed approach, a three-phase four-wire APF connected to a non-linear and unbalanced load has been considered. Experimental results have been generated under ideal and non-ideal voltage sources, showing the effectiveness of the proposed flexible compensation scheme, even for weak grid scenarios
Cultural robotics : The culture of robotics and robotics in culture
Copyright 2013 Samani et al.; licensee InTech. This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly citedIn this paper, we have investigated the concept of "Cultural Robotics" with regard to the evolution o social into cultural robots in the 21st Century. By defining the concept of culture, the potential development of culture between humans and robots is explored. Based on the cultural values of the robotics developers, and the learning ability of current robots, cultural attributes in this regard are in the process of being formed, which would define the new concept of cultural robotics. According to the importance of the embodiment of robots in the sense of presence, the influence of robots in communication culture is anticipated. The sustainability of robotics culture based on diversity for cultural communities for various acceptance modalities is explored in order to anticipate the creation of different attributes of culture between robot and humans in the futurePeer reviewe
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