Numerical Simulation of a Hollow-Core Woodpile-Based Mode Launcher for Dielectric Laser Accelerators

Hollow core microstructures powered by infrared lasers represent a new and promising area of accelerator research, where advanced concepts of electromagnetism must be used to satisfy multiple requirements. Here, we present the design of a dielectric electromagnetic band gap (EBG) mode launcher–converter for high-power coupling in dielectric laser accelerators (DLAs). The device is based on a silicon woodpile structure, and it is composed of two perpendicularly coupled hollow-core waveguides—a transverse electric (TE)-like mode waveguide (excited from laser power) and a transverse magnetic (TM)-like mode (accelerating) waveguide—in analogy with the TE10-to-TM01 waveguide mode converters of radio frequency (RF) linear accelerators (LINACs). The structure is numerically designed and optimized, showing insertion losses (IL) <0.5 dB and efficient mode conversion in the operating bandwidth. The operating wavelength is 5 μm, corresponding to a frequency of ≈60 THz, in a spectral region where solid-state continuous-wave (CW) lasers exist and are actively developed. The presented woodpile coupler shows an interaction impedance in the order of 10 kΩ, high power handling and efficiency

Georadar investigations in the central nave of Hagia Sofia, Istanbul (Turkey)

Within an interdisciplinary project to study Istanbul's Hagia Sofia, a georadar survey was carried out in the central nave to assess if the deformations of the structure previously observed could be related to a differential behavior of the subsoil caused by architectural remains underneath. This study faces an unusual challenge since it was necessary to study the space beneath the scaffolding placed for the restoration works. The survey of the central nave was successful and allowed the detection of remains of walls that probably formed the basement of a previous 18- by 22-m structure. In addition, another interesting feature was discovered 2 m below the marble mosaic in the southeastern part of the nave. Although it is not possible to define its function, it seems that there could be a close relationship between this 2- by 3-m buried structure and the marble mosaic in the floor surface. Although some structures were identified under the floor of Hagia Sofia, there are no major changes in the topography of the central nave floor

The bricks of Hagia Sophia (Istanbul, Turkey): a new hypothesis to explain their compositional difference

The work shows the results of a multi-analytical study performed on twenty-nine brick samples taken from Hagia Sophia in Istanbul (Turkey). Hagia Sophia, one of the most important historical buildings in the world, has a very complex construction history. This complexity is also reflected in the materials that were used for its construction. The main purpose of this work is to verify whether there are any compositional differences in the bricks used in different historical periods, but also to understand the reasons for any compositional differences between one period and another. The samples were studied by optical microscopy (OM), X-ray fluorescence (XRF), X-ray powder diffraction (XRPD) and thermogravimetric analysis (TGA), coupled with a new approach, based on the micro-chemical EDS analysis used to obtain information on the clay fraction of the matrix. The study showed that, most probably, the differences between the bricks belonging to the different construction phases are due to the composition of the clays used for their preparation

Acute Achilles tendon rupture: minimally invasive surgery versus non operative treatment, with immediate full weight bearing. Design of a randomized controlled trial

<p>Abstract</p> <p>Background</p> <p>We present the design of an open randomized multi-centre study on surgical versus conservative treatment of acute Achilles tendon ruptures. The study is designed to evaluate the effectiveness of conservative treatment in reducing complications when treating acute Achilles tendon rupture.</p> <p>Methods/Design</p> <p>At least 72 patients with acute Achilles tendon rupture will be randomized to minimally invasive surgical repair followed by functional rehabilitation using tape bandage or conservative treatment followed by functional rehabilitation with use of a functional bracing system. Both treatment arms use a 7 weeks post-rupture rehabilitation protocol. Four hospitals in the Netherlands will participate. Primary end-point will be reduction in complications other than re-rupture. Secondary end-point will be re-rupturing, time off work, sporting activity post rupture, functional outcome by Leppilahti score and patient satisfaction. Patient follow-up will be 12 month.</p> <p>Discussion</p> <p>By making this design study we wish to contribute to more profound research on AT rupture treatment and prevent publication bias for this open-labelled randomized trial.</p> <p>Trial registration</p> <p>ISRCTN50141196</p

Fermi Large Area Telescope Constraints on the Gamma-ray Opacity of the Universe

The Extragalactic Background Light (EBL) includes photons with wavelengths from ultraviolet to infrared, which are effective at attenuating gamma rays with energy above ~10 GeV during propagation from sources at cosmological distances. This results in a redshift- and energy-dependent attenuation of the gamma-ray flux of extragalactic sources such as blazars and Gamma-Ray Bursts (GRBs). The Large Area Telescope onboard Fermi detects a sample of gamma-ray blazars with redshift up to z~3, and GRBs with redshift up to z~4.3. Using photons above 10 GeV collected by Fermi over more than one year of observations for these sources, we investigate the effect of gamma-ray flux attenuation by the EBL. We place upper limits on the gamma-ray opacity of the Universe at various energies and redshifts, and compare this with predictions from well-known EBL models. We find that an EBL intensity in the optical-ultraviolet wavelengths as great as predicted by the "baseline" model of Stecker et al. (2006) can be ruled out with high confidence.Comment: 42 pages, 12 figures, accepted version (24 Aug.2010) for publication in ApJ; Contact authors: A. Bouvier, A. Chen, S. Raino, S. Razzaque, A. Reimer, L.C. Reye

Gamma-ray and radio properties of six pulsars detected by the fermi large area telescope

We report the detection of pulsed γ-rays for PSRs J0631+1036, J0659+1414, J0742-2822, J1420-6048, J1509-5850, and J1718-3825 using the Large Area Telescope on board the Fermi Gamma-ray Space Telescope (formerly known as GLAST). Although these six pulsars are diverse in terms of their spin parameters, they share an important feature: their γ-ray light curves are (at least given the current count statistics) single peaked. For two pulsars, there are hints for a double-peaked structure in the light curves. The shapes of the observed light curves of this group of pulsars are discussed in the light of models for which the emission originates from high up in the magnetosphere. The observed phases of the γ-ray light curves are, in general, consistent with those predicted by high-altitude models, although we speculate that the γ-ray emission of PSR J0659+1414, possibly featuring the softest spectrum of all Fermi pulsars coupled with a very low efficiency, arises from relatively low down in the magnetosphere. High-quality radio polarization data are available showing that all but one have a high degree of linear polarization. This allows us to place some constraints on the viewing geometry and aids the comparison of the γ-ray light curves with high-energy beam models

Clinical classification and clinical interventions for Post COVID-19 condition: a Scoping Review – Project Protocol

The purpose of this scoping review is to map the available evidence, identify the types and numbers of primary studies, systematic reviews, and real-world evidence available in peer-reviewed journals and grey literature