Calibration of thickness-dependent k-factors for germanium X-ray lines to improve energy-dispersive X-ray spectroscopy of SiGe layers in analytical transmission electron microscopy

We show that the accuracy of energy-dispersive X-ray spectroscopy can be improved by analysing and comparing multiple lines from the same element. For each line, an effective k-factor can be defined that varies as a function of the intensity ratio of multiple lines (e.g. K/L) from the same element. This basically performs an internal self-consistency check in the quantification using differently absorbed X-ray lines, which is in principle equivalent to an absorption correction as a function of specimen thickness but has the practical advantage that the specimen thickness itself does not actually need to be measured

Positive for youth work? Contested terrains of professional youth work in austerity England

© 2014 Taylor & Francis. This article is available open access through the publisher’s website at the link below.This article considers professional youth work in England. It reflects on youth work's persistently anomalous position in the division of labour. Since their achievement of a contested professional status in the 1960s and 1970s, youth workers have pursued an occupational ideology that draws principally on a romantic humanism. Until recently, this provided a relatively stable basis to their practices. Under a dominant contemporary neo-liberalism, influential in different ways across Europe, youth work has been subjected to a range of managerialist practices that have further exposed its ambiguity as a profession. Austerity policy, enacted under the Coalition government, has further weakened professional youth work's position in the welfare division of labour. The article points to resistance to austerity on the part of some youth workers and speculates on the possible future of professional youth work in a policy regime that has little sympathy for the public professions

The Creation and Detection of Arbitrary Photon Number States Using Cavity QED

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Comment on 'Nanoscale mapping of optical band gaps using monochromated electron energy loss spectroscopy' by Zhan, Granerød, Venkatachalapathy, Johansen, Jensen, Kuznetsov and Prytz in Nanotechnology 28 (2017) 105703

Comment on ‘Nanoscale mapping of optical band gaps using monochromated electron energy loss spectroscopy’ by Zhan, Granerød, Venkatachalapathy, Johansen, Jensen, Kuznetsov and Prytz in Nanotechnology 28 (2017) 10570

3D simulations of self-propelled, reconstructed jellyfish using vortex methods

We present simulations of the vortex dynamics associated with the self-propelled motion of jellyfish. The geometry is obtained from image segmentation of video recordings from live jellyfish. The numerical simulations are performed using three-dimensional viscous, vortex particle methods with Brinkman penalization to impose the kinematics of the jellyfish motion. We study two types of strokes recorded in the experiment1. The first type (stroke A) produces two vortex rings during the stroke: one outside the bell during the power stroke and one inside the bell during the recovery stroke. The second type (stroke B) produces three vortex rings: one ring during the power stroke and two vortex rings during the recovery stroke. Both strokes propel the jellyfish, with stroke B producing the highest velocity. The speed of the jellyfish scales with the square root of the Reynolds number. The simulations are visualized in a fluid dynamics video.Comment: 1 page, 1 figur

Gravitationally induced phase shift on a single photon

The effect of the Earth's gravitational potential on a quantum wave function has only been observed for massive particles. In this paper we present a scheme to measure a gravitationally induced phase shift on a single photon travelling in a coherent superposition along different paths of an optical fiber interferometer. To create a measurable signal for the interaction between the static gravitational potential and the wave function of the photon, we propose a variant of a conventional Mach-Zehnder interferometer. We show that the predicted relative phase difference of $10^{-5}$ radians is measurable even in the presence of fiber noise, provided additional stabilization techniques are implemented for each arm of a large-scale fiber interferometer. Effects arising from the rotation of the Earth and the material properties of the fibers are analysed. We conclude that optical fiber interferometry is a feasible way to measure the gravitationally induced phase shift on a single-photon wave function, and thus provides a means to corroborate the equivalence of the energy of the photon and its effective gravitational mass.Comment: 13 pages, 5 figure

Formation of Low Threshold Voltage Microlasers

Vertical cavity surface emitting lasers (VCSELs) with threshold voltages of 1.7V have been fabricated. The resistance-area product in these new vertical cavity lasers is comparable to that of edge-emitting lasers, and threshold currents as low as 3 mA have been measured. Molecular beam epitaxy was used to grow n-type mirrors, a quantum well active region, and a heavily Be-doped p-contact. After contact definition and alloying, passive high-reflectivity mirrors were deposited by reactive sputter deposition of SiO2/Si3N4 to complete the laser cavity