Non-spherical core collapse supernovae III. Evolution towards homology and dependence on the numerical resolution

(abridged) We study the hydrodynamic evolution of a non-spherical core-collapse supernova in two spatial dimensions. We find that our model displays a strong tendency to expand toward the pole. We demonstrate that this expansion is a physical property of the low-mode, SASI instability. The SASI leaves behind a large lateral velocity gradient in the post shock layer which affects the evolution for minutes and hours later. This results in a prolate deformation of the ejecta and a fast advection of Ni-rich material from moderate latitudes to the polar regions. This effect might actually be responsible for the global asymmetry of the nickel lines in SN 1987A. The simulations demonstrate that significant radial and lateral motions in the post-shock region, produced by convective overturn and the SASI during the early explosion phase, contribute to the evolution for minutes and hours after shock revival. They lead to both later clump formation, and a significant prolate deformation of the ejecta which are observed even as late as one week after the explosion. As pointed out recently by Kjaer et al., such an ejecta morphology is in good agreement with the observational data of SN 1987A. Systematic future studies are needed to investigate how the SASI-induced late-time lateral expansion depends on the dominant mode of the SASI, and to which extent it is affected by the dimensionality of the simulations. The impact on and importance of the SASI for the distribution of iron group nuclei and the morphology of the young SNR argues for future three-dimensional explosion and post-explosion studies on singularity-free grids that cover the entire sphere. Given the results of our 2D resolution study, present 3D simulations must be regarded as underresolved, and their conclusions must be verified by a proper numerical convergence analysis in three dimensions.Comment: 16 pages, 20 figures, accepted for publication in Astronomy & Astrophysic

Modeling the X-ray emission of SN 1993J

We investigate the effects of radiative shocks on the observed X-ray emission from the Type II supernova SN 1993J. To this end, the X-ray emission is modeled as a result of the interaction between the supernova ejecta and a dense circumstellar medium at an age of 8 years. The circumstances under which the reverse shock is radiative are discussed and the observed X-ray emission is analyzed using the numerical code described in Nymark et al. (2006). We argue that the original analysis of the X-ray observations suffered from the lack of self-consistent models for cooling shocks with high density and velocity, leading to questionable conclusions about the temperatures and elemental abundances. We reanalyze the spectra with our numerical model, and discuss the expected spectra for different explosion models for the progenitors. We find that the spectra of SN 1993J are compatible with a CNO-enriched composition and that the X-ray flux is dominated by the reverse shock.Comment: 12 pages, 7 figures, 3 tables. Accepted for publication in A&

Massive stars as thermonuclear reactors and their explosions following core collapse

Nuclear reactions transform atomic nuclei inside stars. This is the process of stellar nucleosynthesis. The basic concepts of determining nuclear reaction rates inside stars are reviewed. How stars manage to burn their fuel so slowly most of the time are also considered. Stellar thermonuclear reactions involving protons in hydrostatic burning are discussed first. Then I discuss triple alpha reactions in the helium burning stage. Carbon and oxygen survive in red giant stars because of the nuclear structure of oxygen and neon. Further nuclear burning of carbon, neon, oxygen and silicon in quiescent conditions are discussed next. In the subsequent core-collapse phase, neutronization due to electron capture from the top of the Fermi sea in a degenerate core takes place. The expected signal of neutrinos from a nearby supernova is calculated. The supernova often explodes inside a dense circumstellar medium, which is established due to the progenitor star losing its outermost envelope in a stellar wind or mass transfer in a binary system. The nature of the circumstellar medium and the ejecta of the supernova and their dynamics are revealed by observations in the optical, IR, radio, and X-ray bands, and I discuss some of these observations and their interpretations.Comment: To be published in " Principles and Perspectives in Cosmochemistry" Lecture Notes on Kodai School on Synthesis of Elements in Stars; ed. by Aruna Goswami & Eswar Reddy, Springer Verlag, 2009. Contains 21 figure

MR spectroscopy of hepatic fat and adiponectin and leptin levels during testosterone therapy in type 2 diabetes: a randomized, double-blinded, placebo-controlled trial:A randomized, double-blinded, placebo-controlled trial

Background Men with type 2 diabetes mellitus (T2D) often have lowered testosterone levels and an increased risk of cardiovascular disease (CVD). Ectopic fat increases the risk of CVD, whereas subcutaneous gluteofemoral fat protects against CVD and has a beneficial adipokine-secreting profile. Hypothesis Testosterone replacement therapy (TRT) may reduce the content of ectopic fat and improve the adipokine profile in men with T2D. Design and methods A randomized, double-blinded, placebo-controlled study in 39 men aged 50–70 years with T2D and bioavailable testosterone levels &lt;7.3 nmol/L. Patients were randomized to TRT (n = 20) or placebo gel (n = 19) for 24 weeks. Thigh subcutaneous fat area (TFA, %fat of total thigh volume), subcutaneous abdominal adipose tissue (SAT, % fat of total abdominal volume) and visceral adipose tissue (VAT, % fat of total abdominal volume) were measured by magnetic resonance (MR) imaging. Hepatic fat content was estimated by single-voxel MR spectroscopy. Adiponectin and leptin levels were measured by in-house immunofluorometric assay. Coefficients (b) represent the placebo-controlled mean effect of intervention. Results TFA (b = −3.3 percentage points (pp), P = 0.009), SAT (b = −3.0 pp, P = 0.006), levels of adiponectin (b = −0.4 mg/L, P = 0.045), leptin (b = −4.3 µg/mL, P &lt; 0.001), leptin:adiponectin ratio (b = −0.53, P = 0.001) and HDL cholesterol (b = −0.11 mmol/L, P = 0.009) decreased during TRT compared with placebo. Hepatic fat content and VAT were unchanged. Conclusions The effects of TRT on cardiovascular risk markers were ambiguous. We observed potentially harmful changes in cardiovascular risk parameters, markedly reduced subcutaneous fat and unchanged ectopic fat during TRT and a reduction in adiponectin levels. On the other hand, the decrease in leptin and leptin:adiponectin ratio assessments could reflect an amelioration of the cardiovascular risk profile linked to hyperleptinaemia in ageing men with T2D. </jats:sec

X-ray emission from radiative shocks in Type II supernovae

The X-ray emission from the circumstellar interaction in Type II supernovae with a dense circumstellar medium is calculated. In Type IIL and Type IIn supernovae mass loss rates are generally high enough for the region behind the reverse shock to be radiative, producing strong radiation, particularly in X-rays. We present a model for the emission from the cooling region in the case of a radiative reverse shock. Under the assumption of a stationary flow, a hydrodynamic model is combined with time dependent ionization balance and multilevel calculations. The applicability of the steady state approximation is discussed for various values of the ejecta density gradient and different sets of chemical composition. We show how the emerging spectrum depends strongly on the reverse shock velocity and the composition of the shocked gas. We discuss differences between a spectrum produced by this model and a single-temperature spectrum. Large differences for especially the line emission are found, which seriously can affect abundance estimates. We also illustrate the effects of absorption in the cool shocked ejecta. The applicability of our model for various types of supernovae is discussed.Comment: 25 pages, 15 figures, 4 tables. Accepted for publication in A&

Comparison of hip fracture incidence and trends between Germany and Austria 1995-2004: An epidemiological study

Mann E, Meyer G, Haastert B, Icks A. Comparison of hip fracture incidence and trends between Germany and Austria 1995-2004: an epidemiological study. BMC Public Health. 2010;10(1): 46.Background Several studies evaluated variations in hip fracture incidences, as well as trends of the hip fracture incidences. Comparisons of trends are lacking so far. We compared the incidence rates and, in particular, its trends between Austria and Germany 1995 to 2004 analysing national hospital discharge diagnosis register data. Methods Annual frequencies of hip fractures and corresponding incidences per 100,000 person years were estimated, overall and stratified for sex and age, assuming Poisson distribution. Multiple Poisson regression models including country and calendar year, age and sex were used to analyse differences in incidence and trend. The difference of annual changes between the two countries was explored using an interaction term (calender year * country). Results Overall, the increase of hip fracture risk was 1.31 fold higher (95% CI 1.29-1.34) in Austria compared to Germany, adjusted for age, sex, and calendar year. The risk increase was comparable for both sexes (males: RR 1.35 (1.32-1.37), females: RR 1.31 (1.29-1.33)). Hip fracture trend from 1995 to 2004 indicates an increase in both countries without a statistically significant difference between Austria and Germany (interaction term: p = 0.67). Conclusion In this study comparing hip fracture incidences and its trend using pooled data, the incidence in Austria was 30% higher compared to its neighbouring country Germany. For both countries a similar increasing trend of hip fracture incidence over the 10-year study period was calculated. The results need confirmation by other studies

The hip fracture incidence curve is shifting to the right: A forecast of the age-quake

Background The number of hip fractures has doubled in the last 30–40 years in many countries. Age-adjusted incidence has been reported to be decreasing in Europe and North America, but is there a decreasing trend in all age groups

Augmentation of Reverse Transcription by Integrase through an Interaction with Host Factor, SIP1/Gemin2 Is Critical for HIV-1 Infection

There has been accumulating evidence for the involvement of retroviral integrase (IN) in the reverse transcription of viral RNA. We previously identified a host factor, survival motor neuron-interacting protein 1 (SIP1/Gemin2) that binds to human immunodeficiency virus type 1 (HIV-1) IN and supports HIV-1 infection apparently at reverse transcription step. Here, we demonstrated that HIV-1 IN together with SIP1 augments reverse transcriptase (RT) activity by enhancing the assembly of RT on viral RNA in vitro. Synthetic peptides corresponding to the binding motifs within IN that inhibited the IN-SIP1 interaction abrogated reverse transcription in vitro and in vivo. Furthermore, knockdown of SIP1 reduced intracellular stability and multimer formation of IN through proteasome-mediated degradation machinery. Taken together, SIP1 appears to stabilize functional multimer forms of IN, thereby promoting the assembly of IN and RT on viral RNA to allow efficient reverse transcription, which is a prerequisite for efficient HIV-1 infection

Response of the Diatom Phaeodactylum tricornutum to Photooxidative Stress Resulting from High Light Exposure

The response of microalgae to photooxidative stress resulting from high light exposure is a well-studied phenomenon. However, direct analyses of photosystem II (PSII) D1 protein (the main target of photoinhibition) in diatoms are scarce. In this study, the response of the diatom model species Phaeodactylum tricornutum to short-term exposure to high light was examined and the levels of D1 protein determined immunochemically. Low light (LL) acclimated cells (40 µmol photons m−2 s−1) subjected to high light (HL, 1,250 µmol photons m−2 s−1) showed rapid induction of non-photochemical quenching (NPQ) and ca. 20-fold increase in diatoxanthin (DT) concentration. This resulted from the conversion of diadinoxanthin (DD) to DT through the activation of the DD-cycle. D1 protein levels under LL decreased about 30% after 1 h of the addition of lincomycin (LINC), a chloroplast protein synthesis inhibitor, showing significant D1 degradation and repair under low irradiance. Exposure to HL lead to a 3.2-fold increase in D1 degradation rate, whereas average D1 repair rate was 1.3-x higher under HL than LL, leading to decreased levels of D1 protein under HL. There were significant effects of both HL and LINC on P. tricornutum maximum quantum yield of PSII (Fv/Fm), showing a reduction of active PSII reaction centres. Partial recovery of Fv/Fm in the dark demonstrates the photosynthetic resilience of this diatom to changes in the light regime. P. tricornutum showed high allocation of total protein to D1 and an active D1-repair cycle to limit photoinhibition

Matrix and Tensor Factorization Methods for Toxicogenomic Modeling and Prediction

Peer reviewe