The subdwarf B star SB 290 - A fast rotator on the extreme horizontal branch

Hot subdwarf B stars (sdBs) are evolved core helium-burning stars with very thin hydrogen envelopes. In order to form an sdB, the progenitor has to lose almost all of its hydrogen envelope right at the tip of the red giant branch. In close binary systems, mass transfer to the companion provides the extraordinary mass loss required for their formation. However, apparently single sdBs exist as well and their formation is unclear since decades. The merger of helium white dwarfs leading to an ignition of core helium-burning or the merger of a helium core and a low mass star during the common envelope phase have been proposed. Here we report the discovery of SB 290 as the first apparently single fast rotating sdB star located on the extreme horizontal branch indicating that those stars may form from mergers.Comment: 5 pages, 4 figures, A&A letters, accepte

The population of white dwarf binaries with hot subdwarf companions

Hot subdwarfs (sdBs) are core helium-burning stars, which lost almost their entire hydrogen envelope in the red-giant phase. Since a high fraction of those stars are in close binary systems, common envelope ejection is an important formation channel. We identified a total population of 51 close sdB+WD binaries based on time-resolved spectroscopy and multi-band photometry, derive the WD mass distribution and constrain the future evolution of these systems. Most WDs in those binaries have masses significantly below the average mass of single WDs and a high fraction of them might therefore have helium cores. We found 12 systems that will merge in less than a Hubble time and evolve to become either massive C/O WDs, AM\,CVn systems, RCrB stars or even explode as supernovae type Ia.Comment: 5 pages, 2 figures, to appear in the proceedings of the 19th European White Dwarf Workshop, ASP Conf. Se

The C/EBPβ LIP isoform rescues loss of C/EBPβ function in the mouse

The transcription factor C/EBPβ regulates hematopoiesis, bone, liver, fat, and skin homeostasis, and female reproduction. C/EBPβ protein expression from its single transcript occurs by alternative in-frame translation initiation at consecutive start sites to generate three isoforms, two long (LAP*, LAP) and one truncated (LIP), with the same C-terminal bZip dimerization domain. The long C/EBPβ isoforms are considered gene activators, whereas the LIP isoform reportedly acts as a dominant-negative repressor. Here, we tested the putative repressor functions of the C/EBPβ LIP isoform in mice by comparing monoallelic WT or LIP knockin mice with Cebpb knockout mice, in combination with monoallelic Cebpa mice. The C/EBPβ LIP isoform was sufficient to function in coordination with C/EBPα in murine development, adipose tissue and sebocyte differentiation, and female fertility. Thus, the C/EBPβ LIP isoform likely has more physiological functions than its currently known role as a dominant-negative inhibitor, which are more complex than anticipated

Magnetic-Field Induced Quantum Critical Point in YbRh2_2Si2_2

We report low-temperature calorimetric, magnetic and resistivity measurements on the antiferromagnetic (AF) heavy-fermion metal YbRh$_2$Si$_2$ (${T_N =}$ 70 mK) as a function of magnetic field $B$. While for fields exceeding the critical value ${B_{c0}}$ at which ${T_N\to0}$ the low temperature resistivity shows an ${AT^2}$ dependence, a ${1/(B-B_{c0})}$ divergence of ${A(B)}$ upon reducing $B$ to ${B_{c0}}$ suggests singular scattering at the whole Fermi surface and a divergence of the heavy quasiparticle mass. The observations are interpreted in terms of a new type of quantum critical point separating a weakly AF ordered from a weakly polarized heavy Landau-Fermi liquid state.Comment: accepted for publication in Phys. Rev. Let

Induction of the pro-myelocytic leukaemia gene by type I and type II interferons.

The physiological role of the pro-myelocytic leukaemia (PML) gene product is poorly defined. Among other functions, PML is involved in haematopoietic differentiation and in control of cell growth and tumorigenesis. We investigated the regulation of human PML expression by interferons (IFNs) and IL-1 in various human haematopoietic lines (U937, THP1, HL60, NB4), in human diploid fibroblasts and in human peripheral blood leukocytes. Cytokine-induced modulation of PML expression was assessed by Northern blot analyses, flow cytometry studies and in situ immunolabelling. Our data show that IFNs and IL-1 upregulate PML transcript and protein expression in a time and dose-dependent manner. In situ immunolabelling revealed that upregulation of protein expression by IFN-alpha is a consequence of a marked increase in both the number and the intensity of the staining of so-called PML nuclear bodies. Our data suggest that stimulation of PML expression by interferons and IL-1 may account for upregulation of PML proteins observed in inflammatory tissues and in proliferative states

Logical Rules and a Preliminary Prototype for Translating Mortality Coding Rules from ICD-10 to ICD-11

Iris is a system for coding multiple causes of death in ICD-10 and for the selection of the underlying cause of death, based on a knowledge base composed by a large number of rules. With the adoption of ICD-11, those rules need translation to ICD-11. A pre-project has been carried out to evaluate feasibility of transition to ICD-11, which included the analysis of the logical meta-rules needed for rule translation and development of a prototype support system for the expert that will translate the coding rules