Rhodobacter veldkampii, a new species of phototrophic purple nonsulfur bacteria

We describe a new species of purple nonsulfur bacteria, which has the ability to grow under photoautotrophic growth conditions with sulfide as an electron donor and shows the characteristic properties of Rhodobacter species (i.e., ovoid to rod-shaped cells, vesicular internal photosynthetic membranes, bacteriochlorophyll a and carotenoids of the spheroidene series as photosynthetic pigments). In its physiological properties this new species is particularly similar to the recently described species Rhodobacter adriaticus, but it shows enough differences compared with R. adriaticus and the other Rhodobacter species to be recognized as a separate species. In honor of Hans Veldkamp, a Dutch microbiologist, the name Rhodobacter veldkampii sp. nov. is proposed

Kinetic Energy Transport in Rayleigh--B\'enard Convection

The kinetic energy balance in Rayleigh--B\'{e}nard convection is investigated for the Prandtl number range $0.01\le Pr \le 150$ and for fixed Rayleigh number $Ra=5\cdot10^{6}$. The kinetic energy balance is divided into a dissipation, a production and a flux term. We discuss profiles of all terms and find that the different contributions to the energy balance can be spatially separated into regions where kinetic energy is produced and where kinetic energy is dissipated. Analysing the Prandtl number dependence of the kinetic energy balance, we show that the height-dependence of the mean viscous dissipation is closely related to the flux of kinetic energy. We show that the flux of kinetic energy can be divided into four additive contributions, each representing a different elementary physical process (advection, buoyancy, normal viscous stresses and viscous shear stresses). The behaviour of these individual flux contributions is found to be surprisingly rich and exhibits a pronounced Prandtl number dependence. Different flux contributions dominate the kinetic energy transport at different depth, such that a comprehensive discussion requires a decomposition of the domain into a considerable number of sub-layers. On a less detailed level, our results reveal that advective kinetic energy fluxes play a key role in balancing the near-wall dissipation at low Prandtl number, whereas normal viscous stresses are particularly important at high Prandtl number. Finally, our work reveals that classical velocity boundary layers are deeply connected to the kinetic energy transport, but fail to correctly represent regions of enhanced viscous dissipation

Abundances and kinematics of carbon-enhanced metal-poor stars in the Galactic halo*; A new classification scheme based on Sr and Ba

Carbon-enhanced metal-poor (CEMP) stars span a wide range of stellar populations, from bona fide second-generation stars to later forming stars that provide excellent probes of, e.g., binary mass transfer. Here we analyse 11 metal-poor stars of which 10 are CEMP stars. Based on high signal-to-noise (SNR) X-Shooter spectra, we derive abundances of 20 elements (C, N, O, Na, Mg, Ca, Sc, Ti, Cr, Mn, Fe, Ni, Sr, Y, Ba, La, Ce, Pr, Nd, Eu). From the high SNR spectra, we trace the chemical contribution of the rare earth elements (REE) from various production sites, finding a preference for metal-poor low-mass AGB stars of 1.5Mo in CEMP-s stars, while CEMP-r/s stars may indicate a more massive AGB contribution (2-5Mo). A contribution from the r-process - possibly from neutron star mergers (NSM), is also detectable in the REE abundances, especially in the CEMP-r/s. Combining spectra with Gaia DR2 astrometric data indicates that all but one star in our sample (and most literature stars) belong to the Galactic halo. They exhibit a median orbital eccentricity of 0.7, and are found on both pro- and retrograde orbits. The orbital parameters of CEMP-no and CEMP4s stars are remarkably similar in the 98 stars we study. A special CEMP-no star, with very low Sr and Ba content, possesses the most eccentric orbit among the stars in our sample, passing close to the Galactic centre. Finally, we propose an improved scheme to sub-classify the CEMP stars, making use of the Sr$/$Ba ratio, which can also be used to separate very metal-poor stars from CEMP stars in 93 stars in the metallicity range $-4.2<$[Fe/H]$<-2$. The Sr/Ba ratio can also be used for distinguishing CEMP-s,-r/s and -no stars. The Sr/Ba ratio is also a powerful astro-nuclear indicator, as AGB stars exhibit very different Sr/Ba ratios, compared to fast rotating massive stars and NSM, and it is fairly unbiased by NLTE and 3D corrections.(abridged)Comment: 15 pages, 4 pages appendix, 11 figures, accepted for publication in A&

A collocation method for the solution of the first boundary value problem of elasticity in R^2

We present a spline collocation method for the numerical solution of a system of integral equations on a polygon in ĝ2. This integral equation arises if one solves the first boundary value problem for the Lam'e equation with a double layer potential. The derivation and the analysis of the integral equation is given in detail. The optimal order of the spline collocation method is proved for sufficiently graded meshes

Flicker Explained : guide to IEC for the lighting industry

Flicker, or more precisely temporal light modulation (TLM), has re-emerged as a problem with the introduction of LED-based lighting technology. TLM, meaning variations in light intensity over time, may have negative effects on human health, causing annoyance, headaches, eyestrain and migraine. In addition to the unnecessary suffering TLM causes in individuals, the negative consequences of TLM create an obstacle to broad and rapid adaptation of the new LED-technology and consequently also an obstacle to potential energy savings.This guide gives an introduction to TLM, what it is and how it is measured. The effect of TLM on health is concluded, and also the state of knowledge in its research area. An extended part of this guide discusses the flicker measure short-term flicker indicator, Pst, and the technical report describing it, TR IEC 61547-1:2020 (henceforth referred to as IEC 61547, unless otherwise stated). This report describes the equipment, method and measures required to assess flicker. It is, however, technically complicated and could be very hard to interpret by non-technical readers. For a more detailed investigation and recommended amendments of the IEC 61547, see “Flicker explained – Interpretation of the Technical Report IEC 61547“ which is another product of the project Flicker Explained. For a general guide on TLM measurements, please consult the technical note published by International Commission on Illumination, CIE TN 012:2012

Flicker – a technological overview

Flicker can be annoying, but above all it can have a negative effect on human health; causing irritation, headaches, eye strain and migraines. With the introduction of LED lamps, flicker has once again become a problem. In addition to the unnecessary suffering caused to individuals, the negative consequences create an obstacle to the wide and rapid adoption of new LED technology and thus also an obstacle to potential energy savings.The EU’s new eco-design regulations entered into force in September 2021. These include, for the first time (in Europe) regulatory limits for flicker, creating an urgent need to disseminate knowledge about flicker and how to measure it