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The temperature calibration for cool stars and in particular the Miras continues to be contentious. Lunar occultations have provided radii for many K and M stars and a good temperature calibration has been derived for the hotter non-variable M stars (Ridgway et al. 1980). The situation for the Miras and carbon stars and the metal-rich and metal-poor M stars is, however, not so clear cut. Observations are generally made in some broad-band color such as (R-I), (V-K) or (J-K) and a temperature derived using either the Ridgway et al. (1980) empirical scale or a black-body scale; differences can amount to several hundred degrees. We decided to theoretically explore the effects that extension, metallicity and pulsation could have on colors.
A truthful snapshot of horse welfare conditions is a prerequisite for predicting the impact of any actions intended to improve the quality of life of horses. This can be achieved when welfare information, gathered by different assessors in diverse geographical areas, is valid, comparable and collected in a harmonized way. This paper aims to present the first outcomes of the Animal Welfare Indicators (AWIN) approach: the results of on-farm assessment and a reliable and harmonized data collection system. A total of 355 sport and leisure horses, stabled in 40 facilities in Italy and in Germany, were evaluated by three trained assessors using the AWIN welfare assessment protocol for horses. The AWINHorse app was used to collect, store and send data to a common server. Identified welfare issues were obesity, unsatisfactory box dimensions, long periods of confinement and lack of social interaction. The digitalized data collection was feasible in an on-farm environment, and our results suggest that this approach could prove useful in identifying the most relevant welfare issues of horses in Europe or worldwide.
Besides the link of the HIPPARCOS reference frame to extragalactic objects via radio stars or by the HST, also photographic astrometry is able to calibrate the HIPPARCOS proper motions with regard to an inertial system. Numerical simulations have shown that even with a very small number of well-distributed link fields (3 to 5) the photographic method is competitive with other techniques.
The general picture of research in active flow control for aircraft applications has been continuously changing over the last 20 years. Researchers can now obtain design sensitivities by using numerical flow simulations, and new optical experimental methods can be used that measure flow field data non-intrusively in planes and volumes. These methodological advances enabled significant knowledge increase. The present paper reviews recent progress in active flow control by steady blowing. It appears that two strategies of blowing deserve particular attention. The first uses tangential blowing of thin wall jets to overcome the adverse pressure gradients from locally very large flow turning rates. This approach exploits the potentials of the Coanda effect. The second strategy employs oblique blowing of air jets designed to generate longitudinal vortices in the boundary layer. The longitudinal vortices provide convective redistribution of momentum in the boundary layer, and they also enhance turbulent momentum transport. The sensitivities of these two approaches as observed in fundamental flow investigations and in applications to high-lift aerofoils are described and suited efficiency parameters of blowing are analysed.
The B fields in OB stars (BOB) survey is an ESO large programme collecting spectropolarimetric observations for a large number of early-type stars in order to study the occurrence rate, properties, and ultimately the origin of magnetic fields in massive stars. As of July 2014, a total of 98 objects were observed over 20 nights with FORS2 and HARPSpol. Our preliminary results indicate that the fraction of magnetic OB stars with an organised, detectable field is low. This conclusion, now independently reached by two different surveys, has profound implications for any theoretical model attempting to explain the field formation in these objects. We discuss in this contribution some important issues addressed by our observations (e.g., the lower bound of the field strength) and the discovery of some remarkable objects.
We present near-infrared spectro-interferometric studies of red supergiant (RSG) stars using the VLTI/AMBER instrument, which are compared to previously obtained similar observations of AGB stars. Our observations indicate spatially extended atmospheric molecular layers of water vapor and CO, similar as previously observed for Mira stars. Data of VY~CMa indicate that the molecular layers are asymmetric, possibly clumpy. Thanks to the spectro-interferometric capabilities of the VLTI/AMBER instrument, we can isolate continuum bandpasses, estimate fundamental parameters of our sources, locate them in the HR diagram, and compare their positions to recent evolutionary tracks. For the example of VY CMa, this puts it close to evolutionary tracks of initial mass 25-32 M⊙. Comparisons of our data to hydrostatic model atmospheres, 3d simulations of convection, and 1d dynamic model atmospheres based on self-excited pulsation models indicate that none of these models can presently explain the observed atmospheric extensions for RSGs. The mechanism that levitates the atmospheres of red supergiant is thus a currently unsolved problem.
The objective of the study was to evaluate whether magnetic resonance imaging (MRI) offers the opportunity to reliably analyze body composition of pigs in vivo. Therefore, the relation between areas of loin eye muscle and its back fat based on MRI images were used to predict body composition values measured by dual energy X-ray absorptiometry (DXA). During the study, a total of 77 pigs were studied by MRI and DXA, with a BW ranging between 42 and 102 kg. The pigs originated from different extensive or conventional breeds or crossbreds such as Cerdo Iberico, Duroc, German Landrace, German Large White, Hampshire and Pietrain. A Siemens Magnetom Open was used for MRI in the thorax region between 13th and 14th vertebrae in order to measure the loin eye area (MRI-LA) and the above back fat area (MRI-FA) of both body sides, whereas a whole body scan was performed by DXA with a GE Lunar DPX-IQ in order to measure the amount and percentage of fat tissue (DXA-FM; DXA-%FM) and lean tissue mass (DXA-LM; DXA-%LM). A linear single regression analysis was performed to quantify the linear relationships between MRI- and DXA-derived traits. In addition, a stepwise regression procedure was carried out to calculate (multiple) regression equations between MRI and DXA variables (including BW). Single regression analyses showed high relationships between DXA-%FM and MRI-FA (R2 = 0.89, √MSE = 2.39%), DXA-FM and MRI-FA (R2 = 0.82, √MSE = 2757 g) and DXA-LM and MRI-LA (R2 = 0.82, √MSE = 4018 g). Only DXA-%LM and MRI-LA did not show any relationship (R2 = 0). As a result of the multiple regression analysis, DXA-LM and DXA-FM were both highly related to MRI-LA, MRI-FA and BW (R2 = 0.96; √MSE = 1784 g, and R2 = 0.95, √MSE = 1496 g). Therefore, it can be concluded that the use of MRI-derived images provides exact information about important ‘carcass-traits’ in pigs and may be used to reliably predict the body composition in vivo.
On 2011 July 14, a transient X-ray source, Swift J1822.3–1606, was detected by Swift BAT via its burst activities. It was subsequently identified as a new magnetar upon the detection of a pulse period of 8.4 s. Using follow-up RXTE, Swift, and Chandra observations, we have determined a spin-down rate of Ṗ ~ 3 × 10−13, implying a dipole magnetic field of ~ 5 × 1013 G, second lowest among known magnetars, although our timing solution is contaminated by timing noise. The post-outburst flux evolution is well modelled by surface cooling resulting from heat injection in the outer crust, although we cannot rule out other models. We measure an absorption column density similar to that of the open cluster M17 at 10′ away, arguing for a comparable distance of ~1.6 kpc. If confirmed, this could be the nearest known magnetar.
The improvement of carcass quality is one of the main breeding goals in pig production. To select appropriate breeding animals, it is of major concern to exactly and reliably analyze the body composition in vivo. Therefore, the objective of the study was to examine whether the combination of dual-energy X-ray absorptiometry (DXA) and magnetic resonance imaging (MRI) offers the opportunity to reliably analyze quantitative and qualitative body composition characteristics of different pig breeding groups in vivo. In this study, a total of 77 pigs were studied by DXA and MRI at an average age of 154 days. The pigs originated from different autochthonous or conventional breeds or crossbreeds and were grouped into six breed types: Cerdo Ibérico (Ib); Duroc × Ib (Du_Ib); White Sow Lines (WSL, including German Landrace and German Large White); Hampshire/Pietrain (Pi_Ha, including Hampshire, Pietrain × Hampshire (PiHa) and Pietrain × PiHa); Pietrain/Duroc (Pi_Du, including Pietrain × Duroc (PiDu) and Pietrain × PiDu); crossbred WSL (PiDu_WSL, including Pietrain × WSL and PiDu × WSL). A whole-body scan was performed by DXA with a GE Lunar DPX-IQ in order to measure the amount and percentage of fat tissue (FM; %FM), lean tissue (LM; %LM) and bone mineral, whereas a Siemens Magnetom Open with a large body coil was used for MRI in the thorax region between 13th and 14th vertebrae in order to measure the area of the loin (LA) and the above back fat area (FA) of both body sides. A GLM procedure using SAS 9.2 was used to analyze the data. As expected, the native breed Ib followed by Du_Ib crossbreeds showed the highest %FM (27.2%, 25.0%) combined with the smallest LA (46.2 cm2, 73.6 cm2), whereas Ib had the lowest BW at an average age of 154 days. Pigs with Pi_Ha origin presented the least %FM (12.4%) and largest LA (99.5 cm2). The WSL and PiDu_WSL showed an intermediate body composition. Therefore, it could be concluded that DXA and MRI and especially their combination are very suitable methods to reliably identify differences in body composition and carcass traits among different pig lines in vivo.
The possibility to suppress undesirable diffusion of the base dopant boron in siliconbased bipolar transistor structures by the incorporation of a high concentration of carbon has lead to renewed interest in the behavior of carbon in crystalline silicon. The present paper will review essential features of carbon in silicon including solubility, diffusion mechanisms and precipitation behavior. Based on this information the possibilities to use carbon to influence diffusion of dopants in silicon by the introduction of non-equilibrium concentrations of intrinsic point defects will be discussed as well as the reason for the relatively high resilience against carbon precipitation. Interactions between carbon and oxygen will be mentioned, especially in the context of an as yet unexplained fast out-diffusion of carbon close to the surface.
This paper presents proposals for the synthesis of several group III metal organics (In, Ga, Al compounds) and preliminary results on their use in the MOVPE (metal organic vapor phase epitaxy) of III-V semiconductors. The common feature of all these precursors is that they are saturated by interor intramolecular coordination. They are even non-pyrophoric and air resistant which is an interesting aspect with respect to safe handling. In addition, the compounds are liquid at room temperature with a low but sufficient vapor pressure for MOVPE without additional heating of the source.
MgO single crystals have been irradiated at different temperatures (4 K, 300 K) with electrons of energies varying between 0.3 and 3 MeV. The irradiation induced defects and their reactions during thermal annealing have been investigated by optical absorption spectroscopy and by X-ray diffraction. The relaxation volume (Viel ≈ 1 at.vol. = a3/8) and the migration energy of the interstitial atoms (≈ 1.6 eV) are determined and an ionization induced and thermally assisted migration process is observed for the first time. The relevance of these results for the understanding of the cascade damage observed after neutron- or ion-damage is discussed.
Ga0.5In0.5P has been investigated using optically detected cyclotron resonance and photoluminescence techniques. For the disordered alloy, the electron mass is determined to m*=0.092 m0, and for ordered material (band gap reduction ~ 50 meV) the value m*=0.088 m0 is found. The experimentally deduced values are compared with those obtained from a five-band kp calculation.
A series of spinels were grown by topotaxial solid state reaction on MgO(001) and sapphire(11.2) substrates. The structure of the various spinel/oxide reaction fronts was investigated by cross-sectional high resolution electron microscopy and other methods. While for extremely low misfit the reaction front is completely coherent, different interfacial defects form in other cases, depending on sign and amount of the spinel/oxide lattice misfit. For a large positive misfit, a network of misfit dislocations occured all running along <100<, with Burgers vectors of types a/2 and a/2 pointing out of the interface. The perpendicular Burgers vector component along  permits these dislocations to glide in order to cope with the advancing reaction front, avoiding kinetically unfavourable climb processes. The latter have, however, been observed in negative misfit, where the interfacial dislocations run along <110>, with their Burgers vectors lying in the interface plane. At the sapphire/MgAl2O4 front the structure is completely different. Here the h.c.p.-type oxygen sublattice of sapphire is reconstructed into the f.c.c-type oxygen sublattice of the spinel, which requires a tilt of the MgAl2O4 lattice and the formation of interfacial ledges.
Y2O3 thin films were grown directly on Si (001) by MBE and annealed in-situ under UHV at various annealing temperatures. The samples were investigated in-situ by RHEED and ex-situ by HRTEM. A 7 to 15 Å thick non-uniform interfacial amorphous layer is observed in the as-grown sample. After annealing at 490°C under UHV for 30 minutes the amorphous layer is reduced and a sharp Y2O3/Si interface is obtained. At higher annealing temperatures, YSi2 islands start to form at the Y2O3/Si interface. I-V measurements performed on generic MIS structures show that the annealed samples exhibit higher leakage current density than the as-grown sample, due to reduction of the wide band gap interfacial layer. Leakage current densities in annealed samples remain below 1A/cm2, which is acceptable for future high-κ transistor fabrication.
We demonstrate room temperature laser activity of optically pumped GaN/GalnN-DFB-lasers. The ridge-waveguide DFB lasers were realized on GaN/GalnN double heterostructures grown by low-pressure metal-organic vapor phase epitaxy. The best laser threshold we achieved is 1.9 MW/cm2.
By varying the grating period, the laser emission wavelength could be tuned from 399 to 415 nm. This allows to determine the dispersion relation of the effective refractive index neff(λ) and the spectral dependence of the pump power density at the laser threshold Pth(λ) over the whole emission range. Furthermore, the shift of the emission wavelength with temperature of the DFB-lasers is investigated and is found to be small compared to the emission wavelength shift of the gain maximum.
The use of some specific compound semiconductors in the fabrication of high energy X-ray detectors shows significant potential for X-ray astrophysics space missions. We are currently investigating three high purity crystals - CdZnTe, GaAs and TlBr - as the basis for future hard X-ray detectors (above 10 keV). In this paper we present the first results on CdZnTe and GaAs based detectors and evaluate the factors currently still constraining the performance.
Energy resolutions (FWHM) of 0.9 keV and 1.1 keV at 14 keV and 60 keV, respectively, have been obtained with an epitaxial GaAs detector, while 0.7 keV and 1.5 keV FWHM were measured at the same energies with a CdZnTe detector. Based on these results it is clear, that the next generation of X-ray astrophysics missions now in the planning phase may well consider extending the photon energy range up to ∼100 keV by use of efficient detectors with reasonable spectroscopic capabilities.