Search results for "circular"
showing 10 items of 856 documents
A theoretical approach of the propagation through geometrical constraints in cardiac tissue
2007
International audience; The behaviour of impulse propagation in the presence of non-excitable scars and boundaries is a complex phenomenon and induces pathological consequences in cardiac tissue. In this article, a geometrical con¯guration is considered so that cardiac waves propagate through a thin strand, which is connected to a large mass of cells. At this interface, waves can slow down or even be blocked depending on the width of the strand. We present an analytical approach leading to determine the blockade condition, by introducing planar travelling wavefront and circular stationary wave. Eventually, the in°uence of the tissue geometry is examined on the impulse propagation velocity.
Co-Evolutionary Coupling via a Digital-bio Ecosystem : A Suggestion for a New R&D Model in the Digital Economy
2019
A solution to the critical problem of a dilemma between R&D expansion and productivity decline that a majority of information and communication technology (ICT) leaders have been confronting in the digital economy is expected. It can be expected by a spinoff from economic functionality-seeking GDP-based coevolution cycle to supra-functionality beyond an economic value-seeking uncaptured GDP-driven coevolution cycle. However, the transformation dynamism remains a black box. By means of numerical simulations based on empirical analyses of the development trajectories of global ICT leaders, focusing on Amazon and Finland, together with an intensive review of preceding analyses, this paper atte…
From Buildings' End of Life to Aggregate Recycling under a Circular Economic Perspective: A Comparative Life Cycle Assessment Case Study
2021
The demolition of buildings, apart from being energy intensive and disruptive, inevitably produces construction and demolition waste (C&Dw). Unfortunately, even today, the majority of this waste ends up underexploited and not considered as valuable resources to be re-circulated into a closed/open loop process under the umbrella of circular economy (CE). Considering the amount of virgin aggregates needed in civil engineering applications, C&Dw can act as sustainable catalyst towards the preservation of natural resources and the shift towards a CE. This study completes current research by presenting a life cycle inventory compilation and life cycle assessment case study of two buildin…
Tl-related radiation defects in CsI:Tl
2004
Abstract Angular dependencies of the EPR spectra detected via the magnetic circular dichroism of the optical absorption (MCDA-EPR) observed in the MCDA bands at 355, 411, 425, 442, 465, 536, and 815 nm of γ- or X-irradiated CsI:Tl crystals have been investigated. The MCDA-EPR spectrum at B || [1 0 0] consists of two quartets of intense lines. The spectrum could be satisfactorily explained taking into account hyperfine (hf) interactions of unpaired electron with S= 1 2 with three Tl nuclei I ( 205 Tl , 203 Tl )= 1 2 . Therefore we propose as a model a Tl-trimer centre. The hf interactions along a [1 0 0] direction with two equivalent Tl and one single Tl were observed. As a centre model we p…
Magnetooptical studies of defects and recombination luminescence in LiBaF3
2004
Abstract Optically detected EPR investigations have been performed on the recombination luminescence (RL-EPR) of LiBaF3 crystal, X-irradiated at T=4.2 K . RL-EPR lines of VK- centres were found, as well as further lines of a defect with S= 1 2 and an axial g-tensor with its main axis along a [1 0 0] direction of the crystal. Measurements of the magnetic circular dichroism of the absorption (MCDA) have been performed on LiBaF3 crystals X-irradiated at two temperatures ( 4.2 K and RT). After irradiation at T=4.2 K , the main MCDA bands peak at 453 and 500 nm , but after irradiation at T=300 K , the main bands peak at 444 and 390 nm , there is a change of the sign between the peaks in both cas…
Radiation defects in Ce3+-activated fluorobromozirconate glass-ceramic X-ray storage phosphors
2004
Abstract We report on a photostimulated luminescence (PSL) effect in Ce-doped fluorobromozirconate glasses. Small hexagonal or orthorhombic BaBr2 crystallites are formed in the glass upon annealing. The PSL shows a (381,415) nm doublet which is due to the 5d–4f luminescence of Ce3+ in the orthorhombic BaBr2 crystallites embedded in the glass matrix. The stimulation band of the PSL peaking at 580 nm is probably due to perturbed F centres in the crystallites. After X-irradiation the magnetic circular dichroism of the optical absorption showed a broad band in the spectral range between 440 and 800 nm , having a derivative-like line shape centred at about 600 nm . The spectrum consists of two o…
Recent progress in photoemission microscopy with emphasis on chemical and magnetic sensitivity
1997
Abstract With the improved access to synchrotron radiation sources photoemission electron microscopy is developing into a versatile analytical tool in surface and materials science. The broad spectral range and the well-defined polarization characteristics of synchrotron light permit a unique combination of topographic, chemical, and even magnetic investigations down to a mesoscopic scale. The potentiality of photoemission electron microscopy is demonstrated by several experiments on surfaces and microstructured thin film systems, which have been carried out with a newly designed instrument. We discuss its different modes of operation with respect to both microscopy and spectroscopy. A comb…
Fast elemental mapping and magnetic imaging with high lateral resolution using a novel photoemission microscope
1998
Abstract Using tunable soft X-ray synchrotron radiation and a new-generation photoemission electron microscope with integral sample stage and microarea selector, elemental images and local XANES spectra have been measured. Given the present conditions (PM3 at BESSY), the lateral resolution was in the range of 130 nm with the potential of considerable improvement with high-brilliance sources (a base resolution of 25 nm was obtained in threshold photoemission). Measurements at the oxygen K-edge demonstrate that differences in the local chemical environment of the emitter atom are clearly revealed and can thus be used as a fingerprint technique for its chemical state and geometrical surroundin…
RbBr and CsBr doped with Eu2+ as new competitive X-ray storage phosphors
2001
Abstract After X-irradiation of the alkali halides RbBr and CsBr doped with divalent Eu a significant photostimulated luminescence (PSL) effect was found. In both systems the electron trap centre is an F centre, the hole trap centre is still unknown. The Eu 2+ aggregation with cation vacancies plays an important role. Although all of the different Eu 2+ aggregates seem to show PSL effects, they have different PSL efficiencies, decay times and spectral characteristics. In the case of RbBr:Eu 2+ it was possible to investigate the different Eu 2+ -cation vacancy aggregate states by magnetic circular dichroism of the optical absorption (MCDA) and MCDA-detected electron paramagnetic resonance. I…
Structure of eigenvectors of random regular digraphs
2018
Let $d$ and $n$ be integers satisfying $C\leq d\leq \exp(c\sqrt{\ln n})$ for some universal constants $c, C>0$, and let $z\in \mathbb{C}$. Denote by $M$ the adjacency matrix of a random $d$-regular directed graph on $n$ vertices. In this paper, we study the structure of the kernel of submatrices of $M-z\,{\rm Id}$, formed by removing a subset of rows. We show that with large probability the kernel consists of two non-intersecting types of vectors, which we call very steep and gradual with many levels. As a corollary, we show, in particular, that every eigenvector of $M$, except for constant multiples of $(1,1,\dots,1)$, possesses a weak delocalization property: its level sets have cardin…