Modelling convection in A star atmospheres. Bisectors and lineshapes of HD108642

We present a code, VeDyn, for modelling envelopes and atmospheres of A to F stars focusing on accurate treatment of convective processes. VeDyn implements the highly sophisticated convection model of Canuto and Dubovikov (1998) but is fast and handy enough to be used in practical astrophysical applications. We developed the HME envelope solver for this convection model furtheron to consistently model the envelope together with the stellar atmosphere. The synthesis code SynthV was extended to account for the resulting velocity structure. Finally, we tested our approach on atomic line bisectors. It is shown that our synthetic line bisectors of HD108642 bend towards the blue and are of a magnitude comparable to the observed ones. Even though this approach of modelling convection requires the solution of a coupled system of nonlinear differential equations, it is fast enough to be applicable to many of the investigation techniques relying on model atmospheres.Comment: 3 pages, 3 figure

Renormalized spin coefficients in the accumulated orbital phase for unequal mass black hole binaries

We analyze galactic black hole mergers and their emitted gravitational waves. Such mergers have typically unequal masses with mass ratio of the order 1/10. The emitted gravitational waves carry the inprint of spins and mass quadrupoles of the binary components. Among these contributions, we consider here the quasi-precessional evolution of the spins. A method of taking into account these third post-Newtonian (3PN) effects by renormalizing (redefining) the 1.5 PN and 2PN accurate spin contributions to the accumulated orbital phase is developed.Comment: 10 pages, to appear in Class. Quantum Grav. GWDAW13 Proceedings Special Issue, v2: no typos conjectur

Gravitational-wave research as an emerging field in the Max Planck Society. The long roots of GEO600 and of the Albert Einstein Institute

On the occasion of the 50th anniversary since the beginning of the search for gravitational waves at the Max Planck Society, and in coincidence with the 25th anniversary of the foundation of the Albert Einstein Institute, we explore the interplay between the renaissance of general relativity and the advent of relativistic astrophysics following the German early involvement in gravitational-wave research, to the point when gravitational-wave detection became established by the appearance of full-scale detectors and international collaborations. On the background of the spectacular astrophysical discoveries of the 1960s and the growing role of relativistic astrophysics, Ludwig Biermann and his collaborators at the Max Planck Institute for Astrophysics in Munich became deeply involved in research related to such new horizons. At the end of the 1960s, Joseph Weber's announcements claiming detection of gravitational waves sparked the decisive entry of this group into the field, in parallel with the appointment of the renowned relativist Juergen Ehlers. The Munich area group of Max Planck institutes provided the fertile ground for acquiring a leading position in the 1970s, facilitating the experimental transition from resonant bars towards laser interferometry and its innovation at increasingly large scales, eventually moving to a dedicated site in Hannover in the early 1990s. The Hannover group emphasized perfecting experimental systems at pilot scales, and never developed a full-sized detector, rather joining the LIGO Scientific Collaboration at the end of the century. In parallel, the Max Planck Institute for Gravitational Physics (Albert Einstein Institute) had been founded in Potsdam, and both sites, in Hannover and Potsdam, became a unified entity in the early 2000s and were central contributors to the first detection of gravitational waves in 2015.Comment: 94 pages. Enlarged version including new results from further archival research. A previous version appears as a chapter in the volume The Renaissance of General Relativity in Context, edited by A. Blum, R. Lalli and J. Renn (Boston: Birkhauser, 2020

Bloodstream and endovascular infections due to Abiotrophia defectiva and Granulicatella species

BACKGROUND: Abiotrophia and Granulicatella species, previously referred to as nutritionally variant streptococci (NVS), are significant causative agents of endocarditis and bacteraemia. In this study, we reviewed the clinical manifestations of infections due to A. defectiva and Granulicatella species that occurred at our institution between 1998 and 2004. METHODS: The analysis included all strains of NVS that were isolated from blood cultures or vascular graft specimens. All strains were identified by 16S rRNA sequence analysis. Patients' medical charts were reviewed for each case of infection. RESULTS: Eleven strains of NVS were isolated during the 6-year period. Identification of the strains by 16S rRNA showed 2 genogroups: Abiotrophia defectiva (3) and Granulicatella adiacens (6) or "para-adiacens" (2). The three A. defectiva strains were isolated from immunocompetent patients with endovascular infections, whereas 7 of 8 Granulicatella spp. strains were isolated from immunosuppressed patients, mainly febrile neutropenic patients. We report the first case of "G. para-adiacens" bacteraemia in the setting of febrile neutropenia. CONCLUSION: We propose that Granulicatella spp. be considered as a possible agent of bacteraemia in neutropenic patients

Tumour antigen expression in hepatocellular carcinoma in a low-endemic western area

Background: Identification of tumour antigens is crucial for the development of vaccination strategies against hepatocellular carcinoma (HCC). Most studies come from eastern-Asia, where hepatitis-B is the main cause of HCC. However, tumour antigen expression is poorly studied in low-endemic, western areas where the aetiology of HCC differs. Methods: We constructed tissue microarrays from resected HCC tissue of 133 patients. Expression of a comprehensive panel of cancer-testis (MAGE-A1, MAGE-A3/4, MAGE-A10, MAGE-C1, MAGE-C2, NY-ESO-1, SSX-2, sperm protein 17), onco-fetal (AFP, Glypican-3) and overexpressed tumour antigens (Annexin-A2, Wilms tumor-1, Survivin, Midkine, MUC-1) was determined by immunohistochemistry. Results: A higher prevalence of MAGE antigens was observed in patients with hepatitis-B. Patients with expression of more tumour antigens in general had better HCC-specific survival (P=0.022). The four tumour antigens with high expression in HCC and no, or weak, expression in surrounding tumour-free-liver tissue, were Annexin-A2, GPC-3, MAGE-C1 and MAGE-C2, expressed in 90, 39, 17 and 20% of HCCs, respectively. Ninety-five percent of HCCs expressed at least one of these four tumour antigens. Interestingly, GPC-3 was associated with SALL-4 expression (P=0.001), an oncofetal transcription factor highly expressed in embryonal stem cells. SALL-4 and GPC-3 expression levels were correlated with vascular invasion, poor differentiation and higher AFP levels before surgery. Moreover, patients who co-expressed higher levels of both GPC-3 and SALL-4 had worse HCC-specific survival (P=0.018). Conclusions: We describe a panel of four tumour antigens with excellent coverage and good tumour specificity in a western area, low-endemic for hepatitis-B. The association between GPC-3 and SALL-4 is a novel finding and suggests that GPC-3 targeting may specifically attack the tumour stem-cell compartment

Origin of Galactic and Extragalactic Magnetic Fields

A variety of observations suggest that magnetic fields are present in all galaxies and galaxy clusters. These fields are characterized by a modest strength (10^{-7}-10^{-5} G) and huge spatial scale (~Mpc). It is generally assumed that magnetic fields in spiral galaxies arise from the combined action of differential rotation and helical turbulence, a process known as the alpha-omega dynamo. However fundamental questions concerning the nature of the dynamo as well as the origin of the seed fields necessary to prime it remain unclear. Moreover, the standard alpha-omega dynamo does not explain the existence of magnetic fields in elliptical galaxies and clusters. The author summarizes what is known observationally about magnetic fields in galaxies, clusters, superclusters, and beyond. He then reviews the standard dynamo paradigm, the challenges that have been leveled against it, and several alternative scenarios. He concludes with a discussion of astrophysical and early Universe candidates for seed fields.Comment: 67 pages, 17 figures, accepted for publication in Reviews of Modern Physic

Origin of the Biologically Important Elements

The chemical elements most widely distributed in terrestrial living creatures are the ones (apart from inert helium and neon) that are commonest in the Universe--hydrogen, oxygen, carbon, and nitrogen. A chemically different Universe would clearly have different biology, if any. We explore here the nuclear processes in stars, the early Universe, and elsewhere that have produced these common elements, and, while we are at it, also encounter the production of lithium, gold, uranium, and other elements of sociological, if not biological, importance. The relevant processes are, for the most part, well understood. Much less well understood is the overall history of chemical evolution of the Galaxy, from pure hydrogen and helium to the mix of elements we see today. One implication is that we cannot do a very good job of estimating how many stars and which ones might be orbited by habitable planets

Multi-messenger observations of a binary neutron star merger

On 2017 August 17 a binary neutron star coalescence candidate (later designated GW170817) with merger time 12:41:04 UTC was observed through gravitational waves by the Advanced LIGO and Advanced Virgo detectors. The Fermi Gamma-ray Burst Monitor independently detected a gamma-ray burst (GRB 170817A) with a time delay of ~1.7 s with respect to the merger time. From the gravitational-wave signal, the source was initially localized to a sky region of 31 deg2 at a luminosity distance of 40+8-8 Mpc and with component masses consistent with neutron stars. The component masses were later measured to be in the range 0.86 to 2.26 Mo. An extensive observing campaign was launched across the electromagnetic spectrum leading to the discovery of a bright optical transient (SSS17a, now with the IAU identification of AT 2017gfo) in NGC 4993 (at ~40 Mpc) less than 11 hours after the merger by the One- Meter, Two Hemisphere (1M2H) team using the 1 m Swope Telescope. The optical transient was independently detected by multiple teams within an hour. Subsequent observations targeted the object and its environment. Early ultraviolet observations revealed a blue transient that faded within 48 hours. Optical and infrared observations showed a redward evolution over ~10 days. Following early non-detections, X-ray and radio emission were discovered at the transient’s position ~9 and ~16 days, respectively, after the merger. Both the X-ray and radio emission likely arise from a physical process that is distinct from the one that generates the UV/optical/near-infrared emission. No ultra-high-energy gamma-rays and no neutrino candidates consistent with the source were found in follow-up searches. These observations support the hypothesis that GW170817 was produced by the merger of two neutron stars in NGC4993 followed by a short gamma-ray burst (GRB 170817A) and a kilonova/macronova powered by the radioactive decay of r-process nuclei synthesized in the ejecta