One of the models explaining the high luminosity of pulsing ultra-luminous X-ray sources (pULXs) was suggested by Mushtukov et al. (2015). They showed that the accretion columns on the surfaces of highly magnetized neutron stars can be very luminous due to opacity reduction in the high magnetic field. However, a strong magnetic field leads also to amplification of the electron-positron pairs creation. Therefore, increasing of the electron and positron number densities compensates the cross-section reduction, and the electron scattering opacity does not decrease with the magnetic field magnification. As a result, the maximum possible luminosity of the accretion column does not increase with the magnetic field. It ranges between 1040 − 1041 erg s−1 depending only slightly on the magnetic field strength.

Many intermediate polars are hard X-ray sources. The theory of their hard X-ray radiation is well developed and allows us to determine white dwarf masse in this kind of cataclysmic variables. Here we present the results of determination the masses of 35 white dwarfs in the intermediate polars observed by observatories NuSTAR (10 sources) and Swift/BAT (25 sources). The corresponding mass accrerion rates and the luminosity function were also derived due to accurate distance to the sources well known now after Gaia DR2.

In our comments, we re-evaluate Brugger and others (2018) Lycopodium/Eucalyptus double marker approach, based on the fact that previous evidence already demonstrated that the batch of Eucalyptus tablets used by Brugger and others (2018) is not suitable for quantitative comparisons as they are characterized by inconsistent pollen concentration. We present clear evidence that the Eucalyptus tablets do feature inaccurate pollen concentrations, and are therefore improper for all quantitative comparisons of microfossil extraction methods. Consequently, the results of the quantitative and qualitative assessment of different pollen extraction methods from ice samples compiled by Brugger and others (2018) are highly questionable due to the use of faulty marker tablets.

We present novel results of pollen analyses performed on a 10 m firn core retrieved from Alto dell’Ortles glacier (3840 m a.s.l.), Eastern Italian Alps, in 2009. The objective was to identify and quantify pollen grains retained in the ice to detect annual and interannual variations in the pollen spectra, thus enabling construction of an accurate pollen-based timescale. Up to now, this has been achieved by pollen diagram interpretation. Here we present a statistical approach developed to extract the seasonal/annual signal contained in the pollen spectra of an ice core. The method is based on principal component analyses of pollen assemblages obtained by high-level taxonomical identification. We apply this approach to the Ortles samples, demonstrating that seasonal and yearly variations of the pollen spectra are easily detectable and provide valuable information that can help improve the chronological model of the firn core. This approach can potentially be used for deeper cores as well as other types of archives (e.g. varved sediments), allowing faster, more objective estimation of yearly and seasonal variations than with classical percentage pollen diagrams.

The present article reports on the results and interpretation of a total of 235 radiocarbon dates from Alpine sites in the Ötztal region. Out of these, 88 age determinations were performed on equipment and artifacts associated with the Neolithic Iceman (discovered in 1991), and on a variety of plant and animal specimens collected at his discovery site. Since the material was dispersed over a larger area, 14C dates were important to establish the deposition time of the respective samples. About half of the samples fall into the time period where the Iceman lived, documenting synchronous deposition, whereas the others spread out over several thousand years before and after his lifetime. The other set of samples (147) were collected along the Ötztal Valley to the north, with a few samples collected also south of the Alpine watershed. The samples were mainly from soil profiles and peat bogs above the present-day timberline. Overall, the analysis of the data indicates human presence in these high regions of the Alps throughout the Holocene. While the older botanical and archaeological finds indicate activities of hunting and foraging, the younger ones (after ∼5000 BC) point to an intensification of pasturing. This suggests that early human activity was concentrated at altitudes where natural pastures were found, which were probably more favorable than locations at the bottom of the valleys where flooding and other hazards existed. Early users may have come from south of the water divide spreading into the northern regions, particularly during the summer season. It is possible that the Iceman perished at one of his crossings over the probably well-known high-altitude mountain pass due to reasons not yet fully resolved.

Metal-rich dust disks around white dwarfs are thought to be the debris of tidally disrupted rocky bodies. While normally the number of features to study the planetary material directly is very limited, ancillary gas disks around some of these white dwarfs provide the opportunity to do so. We used our Tübingen Accretion Disk code AcDc, assuming non-LTE conditions, to model the gaseous spectrum component. We investigated the chemical mixture as well as the surface density and effective temperature, and utilized the Ca ii infrared triplet to determine the geometry of the disk.

PG 1034+001 is an extremely hot, helium-rich DO-type star that excites the planetary nebula Hewett 1 and large parts of the surrounding interstellar medium. We present preliminary results of an ongoing spectral analysis by means of non-LTE model atmospheres that consider most elements from hydrogen to nickel. This analysis is based on high-resolution ultraviolet (FUSE, IUE) and optical (VLT/UVES, Keck) data. The results are compared with those of PG 1034+001's spectroscopic twin, the DO star PG 0038+199.

This paper is focused on the transition phase between central stars and white dwarfs, i.e. objects in the effective temperature range 100 000 – 200 000 K. We confine our review to hydrogen-deficient stars because the common H-rich objects are subject of the paper by Ziegler et al. in these proceedings. We address the claimed iron-deficiency in PG1159 stars and [WC] central stars. The discovery of new Ne vii and Ne viii lines in PG1159 stars suggests that the identification of O vii and O viii lines that are used for spectral classification of [WCE] stars is wrong. We then present evidence for two distinct post-AGB evolutionary sequences for H-deficient stars based on abundance analyses of the He-dominated O(He) stars and the hot DO white dwarf KPD 0005+5106. Finally, we report on evidence for an H-deficient post-super AGB evolution sequence represented by the hottest known, carbon/oxygen-atmosphere white dwarf H 1504+65 and the recently discovered carbon-atmosphere “hot DQ” white dwarfs.

We present results of a (F)UV spectral analysis of 15 hot, hydrogen-rich central stars of planetary nebulae (CSPNe) of DAO-type (A 7, A 31, A 35, A 39, NGC 3587, NGC 6720, NGC 6853, NGC 7293, PuWe 1, Sh 2-174) and O(H)-type (A 36, Lo 1, LSS 1362, NGC 1360, NGC 4361). The sample covers a wide range of parameters (Teff ≈ 70–130 kK, log g = 5.4–7.4). It represents different stages of post-AGB evolution. The derived stellar parameters are crucial constraints for AGB nucleosynthesis and stellar evolutionary calculations. Detailed spectral analyses using fully line-blanketed NLTE model atmospheres including 23 elements from hydrogen to nickel are performed. Additional modeling of the ISM line absorption enables to unambigiously identify nearly all observed lines and to improve both, the photospheric as well as the ISM model.

The four known O(He) stars are the only amongst the hottest post-AGB stars whose atmospheres are composed of almost pure helium. Thus, their evolution deviates from the hydrogen-deficient post-AGB evolutionary sequence of carbon-dominated stars like e.g. PG 1159 stars. The origin of the O(He) stars is still not explained. They might be either post-early AGB stars or the progeny of R Coronae Borealis stars. We present preliminary results of a non-LTE spectral analysis based on FUSE and HST/COS observations.

Spindles were isolated from deposited eggs of the Mediterranean mealmoth, Ephestia Kuehniella. Their structure and development were studied using anti-tubulin immunofluorescence. The microtubules were labelled with three different monoclonal antibodies. These were directed against β-tubulin, tyrosinated α-tubulin and acetylated α-tubulin. Significant differences in the staining behaviour were not detected with the three antibodies. An unusual mode of spindle formation was observed during the first mitotic division after fusion of the pronuclei. Several of the ensuing embryonic divisions may show the same phenomenon. Prophase of these divisions was characterised by an irregular arrangement of microtubules in the nuclear area. The microtubule mass in the nuclear area increased concomitantly with chromosome condensation. Microtubular foci, comparable to the forming asters of canonical spindles, were not detected. The formation of an orderly pattern in the microtubule mass was signalled by the appearance of minispindles apparently developing around individual chromosomes. Several minispindles subsequently aligned and formed metaphase-like entities within the nuclear area. The metaphase-like entities, in turn, aligned with one another and gave rise to a conventional bipolar metaphase spindle with small asters. The further development of the spindle was conventional. The chromosomes migrated towards the spindle poles and finally daughter nuclei formed. The anaphase and telophase spindles possessed both a prominent array of interzone microtubules and asters. The events in prophase of early embryonic mitosis of E. kuehniella may represent a rare case of chromosomeinduced spindle formation.

Larval testes of four Lepidoptera species were examined using electron microscopy. The testes of one species, the Mediterranean mealmoth Ephestia kuehniella (Pyralidae), were devoid of intracellular pathogens and serve as a control. In this species, metaphase spindles of primary spermatocytes showed a thick layer of perispindle membranes. The membranes were structurally very similar to the agranular endoplasmic reticulum. Membranes of this type occurred also at high frequency throughout the spindle matrix. The analysis of larval testes of Pieris brassicae (Pieridae) revealed virus-like particles within spermatocytes. In another species, Philudoria potatoria (Lasiocampidae), the spermatocytes possessed intracellular bacteria. Whereas the pathogens were found within the germ cells in these species, a fourth species, Plutella xylosteUa (Plutellide), showed microsporidia within somatic cells of the testis sheath. In all the infected animals, the mass of perispindle membranes was reduced in comparison with spermatocytes of E. kuehniella. However, spindle structure appeared regular in the infected animals. This indicates that a thick layer of perispindle membranes is not decisive for spindle assembly and function in male meiosis of Lepidopera

The protein composition of myelin in the central nervous system (CNS) has changed at the evolutionary transition from fish to tetrapods, when a lipid-associated transmembrane-tetraspan (proteolipid protein, PLP) replaced an adhesion protein of the immunoglobulin superfamily (P0) as the most abundant constituent. Here, we review major steps of proteolipid evolution. Three paralog proteolipids (PLP/DM20/DMα, M6B/DMγ and the neuronal glycoprotein M6A/DMβ) exist in vertebrates from cartilaginous fish to mammals, and one (M6/CG7540) can be traced in invertebrate bilaterians including the planktonic copepod Calanus finmarchicus that possess a functional myelin equivalent. In fish, DMα and DMγ are coexpressed in oligodendrocytes but are not major myelin components. PLP emerged at the root of tetrapods by the acquisition of an enlarged cytoplasmic loop in the evolutionary older DMα/DM20. Transgenic experiments in mice suggest that this loop enhances the incorporation of PLP into myelin. The evolutionary recruitment of PLP as the major myelin protein provided oligodendrocytes with the competence to support long-term axonal integrity. We suggest that the molecular shift from P0 to PLP also correlates with the concentration of adhesive forces at the radial component, and that the new balance between membrane adhesion and dynamics was favorable for CNS myelination.

Spectral analysis by means of Non-LTE model-atmosphere techniques has arrived at a high level of sophistication: fully line-blanketed model atmospheres which consider opacities of all elements from H to Ni allow the reliable determination of photospheric parameters of hot, compact stars. Such models provide a crucial test of stellar evolutionary theory: recent abundance determinations of trace elements like, e.g., F, Ne, Mg, P, S, Ar, Fe, and Ni are suited to investigate on AGB nucleosynthesis. E.g., the strong Fe depletion found in hydrogen-deficient post-AGB stars is a clear indication of an efficient s-process on the AGB where Fe is transformed into Ni or even heavier trans iron-group elements. We present results of recent spectral analyses based on high-resolution UV observations of hot stars.

The business meeting of Commission 36 was held during the General Assembly in Prague on 16 August. It was attended by about 15 members. The issues presented included a review of the work made by members of Commission 36, and the election of the new Organising Committee. We note that a comprehensive report on the activities of the commission during the last triennium has been published in Reports on Astronomy, Transactions IAU Volume XXVIA. The scientific activity of the members of the commission has been very intense, and has led to the publication of a large number of papers.

The rapid thermal processing (RTP) of Cu-rich Cu/In precursors for the synthesis of CuInS2 thin films is possible within a broad processing window regarding leading parameters like top temperature, heating rate, and Cu excess. The key reaction pathway for the CuInS2 phase formation has already been investigated by in-situ energy dispersive X-ray diffraction (EDXRD) for various precursor stoichiometries, heating rates and top temperatures at sulphur partial pressure conditions which are typical for physical vapour deposition processes. According to the phase diagrams of the binary sulphide phases, the sulfur partial pressure strongly determines the occuring crystalline phases. However, a controlled variation of the maximum sulphur partial in a typical RTP experiment has not been carried out yet. In order to study the influence of this parameter a special RTP reaction chamber was designed suitable for in-situ EDXRD experiments at the EDDI beamline at BESSY, Berlin. In a typical in-situ RTP/EDXRD experiment sulphur and a Cu/In/Mo/glass precursor are placed in an evacuated graphite reactor. The amount of sulphur determines the maximum pressure available at the top temperature of the experiment. As the RTP process proceeds a complete EDXRD spectrum is acquired every 10 seconds and thus the various stages of the reaction path and the crystalline phases can be monitored. The first experiments show already a significant change in the reaction pathway and the secondary Cu-S phases which segregate on top of the CuInS2 thin film during the reaction.

The evolution of central stars of planetary nebulae can proceed in several distinct ways, either leading to H-deficiency or to H-normal surface composition. Several new simulations of the evolution channels that lead to H-deficiency are now available, mainly the born-again scenarios that are triggered by a He-shell flash during the hot pre-white dwarf evolution phase. A realistic AGB progenitor evolution is important for correct HRD tracks, that allow mass determinations. New hydrodynamic simulations of He-shell flash convection including cases with H-ingestion are now performed, and allow a determination of the convective extra-mixing efficiency. This has direct consequences for the intershell abundance distribution of AGB stars that can be observed in the H-deficient CSPN.

This work presents data on topographical structure, chemical surface composition, physicochemical properties and corrosion resistance of medical grade titanium after ion implantation. Pure commercial titanium has been implanted with 30 keV Na-, Ca- and P-ions at fluences of 2.0 × 1017 cm-2 and 1.5 × 1017 cm-2, respectively. Some of the samples were heat treated at 600 °C for 40 min. Atomic force microscopy (AFM) was used for surface analysis. The chemical composition was investigated using Rutherford backscattering spectrometry (RBS). Physicochemical investigations were carried out using contact angle measurements to determine the polarity of the modified titanium surfaces. Moreover, the electrokinetic zeta potentials on a physiological pH value have been determined. Finally, the corrosion resistance was examined in simulated body fluid (SBF) containing 4 g/l bovine serum albumin (BSA) using cyclic voltametry.

Considering the P-implantations, the measured depth distribution of phosphorus agrees well with calculations. For the implantation of Na and Ca, the concentration of implanted atoms in the maximum of the depth distribution is noticeably lower and the distribution extends to larger depths compared to the predictions. This finding is associated with a strong incorporation of oxygen over the whole penetration depth of the implanted ions. According to topographical and chemical changes different contact angles as well as zeta potentials have been detected for the ion implanted surfaces compared to pure titanium. The electrochemical examinations indicate that the implantation has no negative influence on the corrosion resistance in comparison to unmodified medical grade titanium. The results show that ion implantation using certain ions can be used to design tailor-made titanium surfaces from a physicochemical point of view.