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ABSTRACT Numerous admixtures are used in the building practice to customize the properties of the cement paste during application. The influences of admixtures on the course of cement hydration and [...]

To improve the treatment of obesity, some researchers are focusing on understanding the effect of dieting on the resting metabolic rate (RMR), the rate at which calories are burned for basic physiological processes while at rest. One theory of why dieters tend to regain the weight they have lost is that restricting caloric intake slows metabolism, so that less energy is needed in the future. However, it is not clear if dieting reduces the RMR over the long term. Wrestlers are a group of athletes who typically go on sudden diets to reach a certain weight limit for competition; after the match or the season they often regain this weight. To determine whether this weight-cycling lowers the RMR, 12 college wrestlers who had competed (with weight-cycling) for at least three seasons were compared with 13 nonwrestlers (controls). All the subjects were men, aged about 19 to 20 years. The controls were of similar weight and body composition to the wrestlers, but had maintained a stable weight. The RMR was measured before, during, and after the wrestling season, and it was found that at baseline (before the season) the wrestlers actually had a significantly higher RMR than the controls. During the wrestling season, after the wrestlers had lost weight, their RMR was not significantly different from that of the controls. After the season, the findings were the same as at baseline, with the RMR of wrestlers higher than that of controls. It was concluded that the repeated cycles of dieting and weight regain did not cause a long-term reduction in the RMR of these wrestlers. (Consumer Summary produced by Reliance Medical Information, Inc.)

Bildgebende Verfahren haben eine große Bedeutung in der Vaskulitisdiagnostik erlangt. Bei Vaskulitiden großer Gefäße (Riesenzellarteriitis, Takayasu-Arteriitis) können Ultraschall, Magnetresonanztomographie (MRT), Computertomographie (CT) und 18F-Fluorodeoxyglucose(FDG)-Positronenemissionstomographie (PET) spezifische Gefäßwandveränderungen darstellen und bei vorhandener Expertise und adäquater Ausrüstung die Diagnose auch ohne Histologie bestätigen. Ultraschall, MRT und CT zeigen eine homogene, konzentrische Arterienwandverdickung, PET einen gesteigerten Glukosestoffwechsel der Arterienwand. Ultraschall ist erste Wahl besonders bei kranial betonter Riesenzellarteriitis. Die Bildgebung sollte vor oder innerhalb weniger Tage nach Beginn der Glukokortikoidtherapie erfolgen, da sich PET-Befunde an allen Arterien sowie Ultraschall- und MRT-Befunde besonders an den Temporalarterien rasch zurückbilden. Eine geplante Bildgebung darf den Beginn einer Glukokortikoidtherapie nicht verzögern.

We analyze SOHO (SOlar Heliospheric Observatory)/SWAN (Solar Wind ANisotropy) hydrogen Lyman‐αdata collected between 1996 and 2018 to derive the solar wind latitudinal distribution over time. Full‐sky interplanetary Lyman‐αmaps are inverted to derive the total hydrogen ionization rate latitude profiles, normalized to proton charge‐exchange and photoionization. Using Interplanetary Scintillation velocities to calculate the velocity‐dependent charge‐exchange cross‐sections, we produce the solar wind flux latitudinal profiles. Finally, we compute solar wind velocity latitude profiles, based on the dynamic pressure and energy flux conservation (calculated from OMNI data) over latitude. SWAN reproduces the Interplanetary Scintillation velocity profiles up to at least ±60°, and also agrees with Ulysses in situ measurements for solar minimum periods in 1996–1997 and 2007. During solar maximum, discrepancies are more frequent because in situ data reflect local solar wind conditions, while SWAN data reflect global conditions in the heliosphere. The SOHO/SWAN instrument is one of the few to derive the global solar wind distribution outside the eclipticThe data analysis produces latitude distributions for the solar wind particle flux and velocity as a function of timeComparison with IPS and Ulysses velocity data confirms the conservation of dynamic pressure and energy flux in the solar wind

The Earth's hydrogen exosphere Lyman‐αradiation was mapped with the Solar Wind Anisotropies/Solar and Heliospheric Observatory (SWAN/SOHO) instrument in January 1996, 1997, and 1998 (low solar activity). The use of a hydrogen absorption cell allowed to disentangle the interplanetary emission from the geocoronal one and to assign the absorbed signal almost entirely to the geocorona. The geocorona was found to extend at least up to 100 Earth radii (RE) with an intensity of 5 Rayleigh, an unprecedented distance well exceeding the recent results of Lyman Alpha Imaging Camera (LAICA) imager (∼50 RE), and encompassing the orbit of the Moon (∼60 RE). We developed a numerical kinetic model of the hydrogen atoms distribution in the exosphere, which includes the solar Lyman‐αradiation pressure and the ionization. The radiation pressure compresses the H exosphere on the dayside, producing a bulge of H density between 3 and 20 RE, which fits observed intensities very well. The SWAN Lyman‐αdistribution of intensity was compared both to LAICA (2015) and to Orbiting Geophysical Observatory number 5 (1968) measurements. Integrated H densities of SWAN at a tangent distance of 7 REare larger than LAICA/Orbiting Geophysical Observatory number 5 by factors 1.1–2.5, while we should expect a stronger effect of the radiation pressure at solar max. We discuss the possible role of H atoms in satellite orbits to explain this apparent contradiction. An onion‐peeling technique is used to retrieve hydrogen number density in the exosphere for the three SWAN observations. They show an excess of density versus models at large distances, which is likely due to nonthermal atoms (not in the model). We find that the geocorona extends to almost twice the distance of the Moonthe H exosphere is compressed by solar radiation pressure, forming a bulge on the daysidethis bulge is enhanced at low solar activity, possibly in relation with a population of Hatoms in satellite orbits

Kamafugites and carbonatites, being materials of volcanic origin with carbonates as their primary minerals, are relatively low in silica and alumina saturation. Their silica and alumina under-saturation is considered a limiting factor in pozzolanic reactivity; however, these materials are currently being utilised as supplementary cementitious materials in Portland cement in Uganda. This paper presents the findings of an experimental study into their pozzolanic and hydration properties. Pastes and mortars made from cement samples blended with test kamafugites and carbonatites were studied for water demand, setting time, heat of hydration and strength development. Results show carbonatites and kamafugites, because of their low saturation of silica and alumina phases, to have less pronounced pozzolanic properties. The results also show no dependence on reactive silica content for pozzolanic performance after 28 days of curing. The kamafugites and carbonatites accelerated early heat of hydration, reduced setting time, and increased water demand. Although the carbonatites are currently utilized in blended Portland cement as natural pozzolans under the EN 197-1 and ASTM C618 cement standards, they do not meet the minimum composition requirement and volatile elements (LOI) demanded by these standards.

Ultrasound is used increasingly for diagnosing large vessel vasculitis (LVV). The application of Doppler in LVV is very different from in arthritic conditions. This paper aims to explain the most important Doppler parameters, including spectral Doppler, and how the settings differ from those used in arthritic conditions and provide recommendations for optimal adjustments. This is addressed through relevant Doppler physics, focusing, for example, on the Doppler shift equation and how angle correction ensures correctly displayed blood velocity. Recommendations for optimal settings are given, focusing especially on pulse repetition frequency (PRF), gain and Doppler frequency and how they impact on detection of flow. Doppler artefacts are inherent and may be affected by the adjustment of settings. The most important artefacts to be aware of, and to be able to eliminate or minimize, are random noise and blooming, aliasing and motion artefacts. Random noise and blooming artefacts can be eliminated by lowering the Doppler gain. Aliasing and motion artefacts occur when the PRF is set too low, and correct adjustment of the PRF is crucial. Some artefacts, like mirror and reverberation artefacts, cannot be eliminated and should therefore be recognised when they occur. The commonly encountered artefacts, their importance for image interpretation and how to adjust Doppler setting in order to eliminate or minimize them are explained thoroughly with imaging examples in this review.

Die Sonographie der Speicheldrüsen ist eine leicht erlernbare, schnell durchführbare, nichtinvasive, kostengünstige und spezifische Untersuchung zur Detektion pathologischer Veränderungen der Speicheldrüsen in der Diagnostik des Sjögren-Syndroms. Andere bildgebende Verfahren wie Sialographie und Szintigraphie werden nur noch selten eingesetzt. Zur Untersuchung eignen sich Linearschallköpfe mit einer Frequenz zwischen 7 und 12 MHz, die dem in der Sonographie der Bewegungsorgane geschulten Rheumatologen ohnehin zur Verfügung stehen. Standardmäßig werden Glandula parotis und submandibularis beidseits in Longitudinal- und Transversalschnitten durchgemustert. Normale Speicheldrüsen sind echoreich und homogen. Sie lassen sich gut von der umgebenden Muskulatur abgrenzen. Speichel- und Schilddrüsengewebe haben eine ähnliche sonographische Morphologie. Beim Sjögren-Syndrom sind die Speicheldrüsen typischerweise echoarm und inhomogen. Es finden sich fokale oder diffuse echoarme oder echofreie Regionen. Die Glandulae submandibulares können atrophieren (sagittaler Durchmesser <8 mm). Die Glandulae parotidae können bei Krankheitsschüben anschwellen (sagittaler Durchmesser >20 mm). Die Sensitivität für die Diagnose wird mit 60 und 90 %, die Spezifität mit über 90 % angegeben. Eine zusätzliche farbkodierte Dopplersonographie führt nicht zu einer Verbesserung der diagnostischen Aussage. Damit ist die Sonografie ein wichtiger Baustein in der Diagnostik des Sjögren-Syndroms geworden. Ultrasound of the salivary glands is a specific examination for detecting pathology of salivary glands in the diagnosis of Sjögren’s syndrome. It is easy to learn, rapidly performed, non-invasive and inexpensive. Other imaging techniques, such as sialography and scintigraphy, are currently only rarely performed. For the examination, linear ultrasound probes with frequencies between 7 and 12 MHz are recommended. Such probes are already widely available to the rheumatologist performing musculoskeletal ultrasound. The parotid and submandibular glands are bilaterally scanned both in longitudinal and transverse planes as a standard. Normal salivary glands have uniformly hyperechoic and homogeneous tissue. They can be clearly delineated from the surrounding muscles and soft tissue and appear similar to the thyroid gland. The salivary glands are typically hypoechoic and inhomogeneous in Sjögren’s syndrome. Focal or diffuse hypoechoic or anechoic foci are found in the glands. The submandibular glands may become atrophic (sagittal diameter <8 mm). Particularly in disease flares, the parotid glands may become enlarged (sagittal diameter >20 mm). The sensitivity for the diagnosis is 60 to 90% and the specificity is over 90%. Doppler sonography does not further improve the diagnostic accuracy. Sonography has thus become an important tool in the diagnosis of Sjögren’s syndrome.

Transient control over the atomic potential-energy landscapes of solids could lead to new states of matter and to quantum control of nuclear motion on the timescale of lattice vibrations. Recently developed ultrafast time-resolved diffraction techniques combine ultrafast temporal manipulation with atomic-scale spatial resolution and femtosecond temporal resolution. These advances have enabled investigations of photo-induced structural changes in bulk solids that often occur on timescales as short as a few hundred femtoseconds. In contrast, experiments at surfaces and on single atomic layers such as graphene report timescales of structural changes that are orders of magnitude longer. This raises the question of whether the structural response of low-dimensional materials to femtosecond laser excitation is, in general, limited. Here we show that a photo-induced transition from the low- to high-symmetry state of a charge density wave in atomic indium (In) wires supported by a silicon (Si) surface takes place within 350 femtoseconds. The optical excitation breaks and creates In–In bonds, leading to the non-thermal excitation of soft phonon modes, and drives the structural transition in the limit of critically damped nuclear motion through coupling of these soft phonon modes to a manifold of surface and interface phonons that arise from the symmetry breaking at the silicon surface. This finding demonstrates that carefully tuned electronic excitations can create non-equilibrium potential energy surfaces that drive structural dynamics at interfaces in the quantum limit (that is, in a regime in which the nuclear motion is directed and deterministic). This technique could potentially be used to tune the dynamic response of a solid to optical excitation, and has widespread potential application, for example in ultrafast detectors.

Corrole compounds attract increasing interest due to their potential to stabilize high-valent metal states. X-ray spectroscopy is a powerful tool for the investigation and development of functional interfaces. For corrolic species, however, the required reference data are missing. Here, we employ a multitechnique X-ray investigation of thin films of the prototypical free-base 5,10,15-tris(pentafluorophenyl)corrole (3H-TpFPC) grown on the Ag(111) surface under ultrahigh vacuum conditions. Ultrapure corrole multilayer samples are prepared and characterized by X-ray photoelectron spectroscopy (XPS) and near-edge X-ray absorption fine structure (NEXAFS) spectroscopy. In parallel, the X-ray fingerprints are simulated using the continued-fraction approach within density functional theory (DFT) for extended, (quasi-)periodic molecular structures. An excellent agreement between experimental and theoretical spectra enables a thorough interpretation of the detailed spectral features and proves an accurate description of the free-base corrole electronic structure within the present DFT approach. The present study provides X-ray spectroscopic references for all relevant core-level regions and absorption edges of intact molecular species and, thus, represents an ideal starting point for the comprehensive understanding of the complex chemistry of corroles in the adsorbed state toward the development of related functional interfaces.

Product modularization enables a combination of standardization and cost reduction without neglecting the concept of individualization. The major benefit is to maximize external diversity and minimize internal complexity by modular product structures. For a modular product structure and interface design of machine tools combining complementary manufacturing processes in a single machine system, a detailed understanding of the individual technologies and mutual interdependencies is essential to identify complexity and estimate the imminent development effort. Product configuration and conceptualization for integrated machine tools basically depend on the interactions of the manufacturing technologies and the required effort for realization. Platform concepts carry high potential for rationalization, due to similar structures and components and facilitate a fast and low-risk product development process in general.

Context. Colliding flows are a commonly used scenario for the formation of molecular clouds in numerical simulations. Turbulence is produced by cooling, because of the thermal instability of the warm neutral medium.

Aims.We study the structure of the magnetic elements in network-cell interiors.

Aims.We study the structure of the photospheric magnetic field of the quiet Sun by investigating weak spectro-polarimetric signals.

Aims.We investigate the relationship between the photospheric magnetic field and the emission of the mid chromosphere of the Sun.

In thermonuclear supernovae, intermediate mass elements are mostly produced by distributed burning provided that a deflagration to detonation transition does not set in. Apart from the two-dimensional study by Röpke & Hillebrandt (2005, A&A, 429, L29), very little attention has been payed so far to the correct treatment of this burning regime in numerical simulations. In this article, the physics of distributed burning is reviewed from the literature on terrestrial combustion and differences which arise from the very small Prandtl numbers encountered in degenerate matter are pointed out. Then it is shown that the level set method continues to be applicable beyond the flamelet regime as long as the width of the flame brush does not become smaller than the numerical cutoff length. Implementing this constraint with a simple parameterisation of the effect of turbulence onto the energy generation rate, the production of intermediate mass elements increases substantially compared to previous simulations, in which the burning process was stopped once the mass density dropped below 107g cm-3. Although these results depend on the chosen numerical resolution, an improvement of the constraints on the the total mass of burning products in the pure deflagration scenario can be achieved.

Aims.We investigate the morphological, dynamical, and evolutionary properties of the internetwork and network fine structure of the quiet sun at disk centre.

Aims.In this work we investigate the dynamic behavior of inter-network regions of the solar chromosphere.

Aims.Interplanetary Lyman αline profiles are derived from the SWAN H cell data measurements. The measurements cover a 6-year period from solar minimum (1996) to after the solar maximum of 2001. This allows us to study the variations of the line profiles with solar activity.

Aims.We present a spectral analysis of small-scale structures in the solar photosphere and investigate the influence of the speckle deconvolution technique on the line profiles.

We present a one-equation subgrid scale model that evolves the turbulence energy corresponding to unresolved velocity fluctuations in large eddy simulations. The model is derived in the context of the Germano consistent decomposition of the hydrodynamical equations. The eddy-viscosity closure for the rate of energy transfer from resolved toward subgrid scales is localised by means of a dynamical procedure for the computation of the closure parameter. Therefore, the subgrid scale model applies to arbitrary flow geometry and evolution. For the treatment of microscopic viscous dissipation a semi-statistical approach is used, and the gradient-diffusion hypothesis is adopted for turbulent transport. A priori tests of the localised eddy-viscosity closure and the gradient-diffusion closure are made by analysing data from direct numerical simulations. As an a posteriori testing case, the large eddy simulation of thermonuclear combustion in forced isotropic turbulence is discussed. We intend the formulation of the subgrid scale model in this paper as a basis for more advanced applications in numerical simulations of complex astrophysical phenomena involving turbulence.

We apply an ad hocmodel for dynamical ignition in three-dimensional numerical simulations of thermonuclear supernovae assuming pure deflagrations. The model makes use of the statistical description of temperature fluctuations in the pre-supernova core proposed by Wunsch & Woosley (2004, ApJ, 616, 1102). Randomness in time is implemented by means of a Poisson process. We are able to vary the explosion energy and nucleosynthesis depending on the free parameter of the model which controls the rapidity of the ignition process. However, beyond a certain threshold, the strength of the explosion saturates and the outcome appears to be robust with respect to the number of ignitions. In the most energetic explosions, we find about $0.75~M_{\odot}$of iron group elements. Other than in simulations with simultaneous multi-spot ignition, the amount of unburned carbon and oxygen at radial velocities of a few $10^{3}\,{\rm km\,s^{-1}}$tends to be reduced for an ever increasing number of ignition events and, accordingly, more pronounced layering results.

We present first measurements and the calibration procedure for the Polarimetric Littrow Spectrograph (POLIS) operated at the Vacuum Tower Telescope on Tenerife, together with a brief summary of the technical characteristics of the instrument. In its present configuration, we achieve a polarimetric accuracy of about $3 \times 10^{-3}$in the visible channel (630 nm) of the instrument. The accuracy is limited by cross talk among the different polarization states. The detection limit for polarized light is about $2 \times 10^{-3}$for a 7 s exposure. Polarimetric measurements in the blue channel ($\ion{Ca}{ii}$H line, 396.7 nm) are strongly limited by the low photon flux. At this wavelength we present Stokes-Vmaps with a spatial resolution of about 0.5 arcs. The polarimetric quality of any spectropolarimeter is limited by the precision of the instrument calibration. We present a new method for self-calibration that reduces cross talk among the polarization components to 0.1%. This improvement results from a measurement of the retardance of the calibration waveplate with an accuracy of 0.1°. We demonstrate the capability of the simultaneous use of POLIS and the Tenerife Infrared Polarimeter which is integrated in the main spectrograph of the Vacuum Tower Telescope.

A detailed analysis of high-resolution spectra obtained in three different wavelength regions (at 430 nm, 526 nm and 569 nm) of G-band bright points in the solar photosphere is presented. They show an average intensity contrast of 11% with respect to the “quiet” sun reference. The CH lines are weakened in the bright point interior. The atomic lines, too, e.g. the Fe I line at 569.15 nm, weaken in the bright point interior. In contrast thereto, the absorption line of single ionized iron at 526.48 nm remains almost constant between bright point interior and the immediate surroundings. Line-of-sight velocities show a stronger downflow within bright points than in the close environment. A net downflow relative to the intergranular surroundings of around 80 m/s is measured. Filling factors are calculated from a comparison with synthesized spectra for different flux tube models and are used to estimate the “true” velocity in bright points with respect to their immediate surroundings. We obtain up- and downflows in the order of one km s-1, in agreement with the magneto-convective picture of the formation and dispersal of magnetic flux tubes. From the different behavior of the metallic lines and the CH lines we conclude that the line-weakening process that leads to the G-band bright points is mainly due to hot-wall radiation. This confirms that these bright points are indeed magnetic flux elements.

Die spinale epidurale Lipomatose (SEL) der Brust- und Lendenwirbelsäule ist eine seltene Entität, die zur Kompression des Spinalkanals führt. Bei nicht eindeutig geklärter Pathogenese tritt diese am häufigsten bei Patienten mit langzeitigem exogenem oder endogenem Glukokortikoidüberschuss oder morbidem Übergewicht auf, zudem gibt es idiopathische Formen. Die Symptome sind von der Ausprägung der SEL abhängig. Neben asymptomatischen Verläufen können unspezifische Rückenschmerzen, Radiokulopathien und Rückenmarkkompressionssyndrome auftreten. Die Diagnose erfolgt üblicherweise über eine MRT-Darstellung der betroffenen Wirbelsäulensegmente. Die Therapie variiert zwischen dem Absetzen der Glukokortikoide, einer Gewichtsabnahme bis hin zur mehrstufigen dekompressiven Laminektomie. Die folgende Kasuistik stellt den Befund einer SEL bei einem Patienten mit steroidabhängigem Jo-1-Antikörper-Syndrom vor und bietet eine aktuelle Literaturübersicht zu dieser seltenen Erkrankung. Spinal epidural lipomatosis (SEL) of the thoracic and lumbar spine is a rare entity, which leads to compression of the spinal canal. The exact pathogenesis is still unknown. It most commonly occurs in patients with long-term exogenous or endogenous glucocorticoid excess or morbid obesity but there are also idiopathic forms. The symptoms depend on the severity of the SEL and can manifest as clinically asymptomatic, non-specific back pain, radiculopathy up to spinal cord compression. The diagnosis is usually achieved by magnetic resonance imaging (MRI) of the affected spinal segments. The treatment varies between discontinuation of glucocorticoids, weight reduction up to multisegmental decompressive laminectomy. The following case report presents the findings of SEL in a patient with steroid-dependent Jo-1 antibody syndrome and provides a current literature review on this rare disease.

Two hundred fifty‐two transient drops in atmospheric pressure, likely caused by passing convective vortices, were detected by the Rover Environmental Monitoring Station instrument during the first Martian year of the Mars Science Laboratory (MSL) landed mission. These events resembled the vortex signatures detected by the previous Mars landers Pathfinder and Phoenix; however, the MSL observations contained fewer pressure drops greater than 1.5 Pa and none greater than 3.0 Pa. Apparently, these vortices were generally not lifting dust as only one probable dust devil has been observed visually by MSL. The obvious explanation for this is the smaller number of strong vortices with large central pressure drops since according to Arvidson et al. [[Arvidson, R. E., 2014]] ample dust seems to be present on the surface. The annual variation in the number of detected convective vortices followed approximately the variation in Dust Devil Activity (DDA) predicted by the MarsWRF numerical climate model. This result does not prove, however, that the amount of dust lifted by dust devils would depend linearly on DDA, as is assumed in several numerical models of the Martian atmosphere, since dust devils are only the most intense fraction of all convective vortices on Mars, and the amount of dust that can be lifted by a dust devil depends on its central pressure drop. Sol‐to‐sol variations in the number of vortices were usually small. However, on 1 Martian solar day a sudden increase in vortex activity, related to a dust storm front, was detected. Signs of 252 dustless convective vortices have been detected by Mars Science LaboratoryThe annual variation in vortex occurrence rate followed approximately dust devil activity predicted by a numerical climate modelA transient increase in vortex activity related to a dust storm front was detected by meteorological measurements on Mars

We report a detailed analysis of the line shapes of the 0–0 transitions in the fluorescence (FL) and fluorescence excitation (FLE) spectra of perylene-3,4,9,10-tetracarboxylic acid dianhydride (PTCDA) molecules adsorbed at terrace and step edge sites of (100)-oriented alkali halide films (KCl and NaCl). At low temperatures (6–20 K), we find very narrow FLE lines with a fwhm of 4.5 cm–1(3.0 cm–1) on KCl (NaCl). These line shapes are dominated by inhomogeneous broadening related to the structural variation of the environment of the PTCDA molecules. We explain this site broadening on the basis of structural models for the adsorption sites at the step edges from earlier scanning microscopy data and density functional theory calculations. With increasing temperatures, the 0–0 lines in the FL and FLE spectra broaden; e.g., in the FL, the fwhm increases to 26 cm–1(18 cm–1) at 100 K on the KCl (NaCl) surface. This temperature induced broadening is of Lorentzian shape and can be described by the theory of Hsu and Skinner, based on dephasing by coupling to acoustic phonons of the substrate. Discrepancies remain for experimentally observed small line shifts. We discuss how surfaces can be used and optimized as sample systems for a highly resolved optical spectroscopy of molecules.

For reasons of high flexibility but still maximum productivity, machine tools integrating various production technologies have recently received particular attention. Combining and integrating multiple manufacturing techniques into one single system in early stages of the product emergence process is challenging. To keep the effort for implementation to a minimum, an initiation already in the concept phase is being actively pursued. Design guidelines are currently investigated based on the examination of different technology combinations.

We took two-dimensional spectra with the filter spectrometer TESOS at the German Vacuum Tower Telescope, Tenerife, of an absorption line of the CH molecule and a Fe II-line in the ${G}$-band at 430.3 nm. We observed a region, close to disk center of the Sun, that showed a lot of structures with enhanced ${G}$-band intensity (up to 1.3 times the mean intensity of normal granulation). Our spectroscopic investigation of these structures suggests two classes which differ in their spectroscopic signature: (a) Bright structures caused by significant (up to 40%) weakening of absorption lines of the CH molecule; (b) bright structures only caused by an enhanced continuum intensity. In order to distinguish between those two classes we introduce a Bright Point Index (BPI) defined by the ratio of the normalized line depressions of the Fe II and the CH-line. The bright structures caused by weakening of the CH-lines have high BPI values and are accompanied by downflows. The remaining ${G}$-band bright structures have low BPI and are related to granules.

We present several new sets of grids of model stellar atmospheres computed with modified versions of the ATLAS9 code. Each individual set consists of several grids of models with different metallicities ranging from [M/H] $= -$2.0 to +1.0 dex. The grids range from 4000 to 10 000 K in Teffand from 2.0 to 5.0 dex in $\log{g}$. The individual sets differ from each other and from previous ones essentially in the physics used for the treatment of the convective energy transport, in the higher vertical resolution of the atmospheres and in a finer grid in the (Teff, $\log{g}$) plane. These improvements enable the computation of derivatives of color indices accurate enough for pulsation mode identification. In addition, we show that the chosen vertical resolution is necessary and sufficient for the purpose of stellar interior modelling. To explain the physical differences between the model grids we provide a description of the currently available modifications of ATLAS9 according to their treatment of convection. Our critical analysis of the dependence of the atmospheric structure and observable quantities on convection treatment, vertical resolution and metallicity reveals that spectroscopic and photometric observations are best represented when using an inefficient convection treatment. This conclusion holds whatever convection formulation investigated here is used, i.e. MLT($\alpha=0.5$), CM and CGM are equivalent. We also find that changing the convection treatment can lead to a change in the effective temperature estimated from Strömgren color indices from 200 to 400 K.

Polycyclic Aromatic Hydrocarbons (PAHs) are thought to be the carriers of the ubiquitous infrared emission bands (UIBs). Data from the Infrared Space Observatory (ISO) have provided new insights into the size distribution and the structure of interstellar PAH molecules pointing to a trend towards larger-size PAHs. The mid-infrared spectra of galactic and extragalactic sources have also indicated the presence of 5-ring structures and PAH structures with attached side groups. This paper reports for the first time the laboratory measurement of the UV–Vis–NIR absorption spectra of a representative set of large PAHs that have also been selected for a long duration exposure experiment on the International Space Station ISS. PAHs with sizes up to 600 amu, including 5-ring species and PAHs containing heteroatoms, have been synthesized and their spectra measured using matrix isolation spectroscopy. The spectra of the neutral species and the associated cations and anions measured in this work are also compared to astronomical spectra of Diffuse Interstellar Bands (DIBs).

We investigate the thermal and morphological fine structure of a small sunspot, which includes the determination of brightness temperatures and characteristic spatial scales as well as their distribution inside the sunspot. The identification and isolation of sunspot fine structure is accomplished by means of a feature-finding algorithm applied to a high-resolution time sequence taken simultaneously in three continuum bands of the solar spectrum. In order to compensate for seeing and instrumental effects, we apply the phase-diversity technique combined with a deconvolution method. The findings can be summarized as follows: (1) umbral dots are found to be on average 760 K cooler than the immediate surrounding photosphere outside the spot. (2) Some exceptional hot penumbral grains exceed the average temperature of the brightest granules of the spots surroundings by typically 150 K. (3) The size distribution of umbral dots and penumbral grains support the idea that the smallest structures are still spatially unresolved. (4) The distribution function of umbral dot peak intensities points to the existence of two umbral dot “populations” indicating different efficiency of energy transport. (5) The classification of penumbral filaments into “dark” and “bright” depends on the immediate surroundings.

We measure the center-to-limb-variation of the CH lines in the wavelength range from 430.40 to 430.61 nm (G-band) for both quiet sun and for the cooler atmophere of sunspot umbrae at different heliographic positions. The limb effect of the CH lines is about 650 ms-1at $\mu=0.1$with a slope similar to weak Fe lines. We investigate the behaviour of the CH abundance in the range of optical depth ($\tau=-0.05$to $\tau=-0.25$) that is accessible by center-to-limb observations. The CH abundance decreases with height in accordance with recent numerical models.