A High-Resolution Spectroscopic Search for the Remaining Donor for Tycho's Supernova

In this paper, we report on our analysis using Hubble Space Telescope astrometry and Keck-I HIRES spectroscopy of the central six stars of Tycho's supernova remnant (SN 1572). With these data, we measured the proper motions, radial velocities, rotational velocities, and chemical abundances of these objects. Regarding the chemical abundances, we do not confirm the unusu- ally high [Ni/Fe] ratio previously reported for Tycho-G. Rather, we find that for all metrics in all stars, none exhibit the characteristics expected from traditional SN Ia single-degenerate-scenario calculations. The only possible exception is Tycho-B, a rare, metal-poor A-type star; however, we are unable to find a suitable scenario for it. Thus, we suggest that SN 1572 cannot be explained by the standard single-degenerate model.Comment: 34 pages, 11 Figures, revised and resubmitted to Ap

Light-cone distribution amplitudes of octet baryons from lattice QCD

We present lattice QCD results for the wave function normalization constants and the first moments of the distribution amplitudes for the lowest-lying baryon octet. The analysis is based on a large number of $N_f=2+1$ ensembles comprising multiple trajectories in the quark mass plane including physical pion (and kaon) masses, large volumes, and, most importantly, five different lattice spacings down to $a=0.039\,\mathrm{fm}$. This allows us to perform a controlled extrapolation to the continuum and infinite volume limits by a simultaneous fit to all available data. We demonstrate that the formerly observed violation of flavor symmetry breaking constraints can, indeed, be attributed to discretization effects that vanish in the continuum limit

Activation energies for two steps in the S_2 → S_3 transition of photosynthetic water oxidation from time-resolved single-frequency infrared spectroscopy

The mechanism of water oxidation by the Photosystem II (PSII) protein–cofactor complex is of high interest, but specifically, the crucial coupling of protonation dynamics to electron transfer (ET) and dioxygen chemistry remains insufficiently understood. We drove spinach-PSII membranes by nanosecond-laser flashes synchronously through the water-oxidation cycle and traced the PSII processes by time-resolved single-frequency infrared (IR) spectroscopy in the spectral range of symmetric carboxylate vibrations of protein side chains. After the collection of IR-transients from 100 ns to 1 s, we analyzed the proton-removal step in the S2 ⇒ S3 transition, which precedes the ET that oxidizes the Mn4CaOx-cluster. Around 1400 cm−1, pronounced changes in the IR-transients reflect this pre-ET process (∼40 µs at 20 °C) and the ET step (∼300 µs at 20 °C). For transients collected at various temperatures, unconstrained multi-exponential simulations did not provide a coherent set of time constants, but constraining the ET time constants to previously determined values solved the parameter correlation problem and resulted in an exceptionally high activation energy of 540 ± 30 meV for the pre-ET step. We assign the pre-ET step to deprotonation of a group that is re-protonated by accepting a proton from the substrate–water, which binds concurrently with the ET step. The analyzed IR-transients disfavor carboxylic-acid deprotonation in the pre-ET step. Temperature-dependent amplitudes suggest thermal equilibria that determine how strongly the proton-removal step is reflected in the IR-transients. Unexpectedly, the proton-removal step is only weakly reflected in the 1400 cm−1 transients of PSII core complexes of a thermophilic cyanobacterium (T. elongatus)

All‐Organic Battery Based on Deep Eutectic Solvent and Redox‐Active Polymers

Sustainable battery concepts are of great importance for the energy storage demands of the future. Organic batteries based on redox-active polymers are one class of promising storage systems to meet these demands, in particular when combined with environmentally friendly and safe electrolytes. Deep Eutectic Solvents (DESs) represent a class of electrolytes that can be produced from sustainable sources and exhibit in most cases no or only a small environmental impact. Because of their non-flammability, DESs are safe, while providing an electrochemical stability window almost comparable to established battery electrolytes and much broader than typical aqueous electrolytes. Here, we report the first all-organic battery cell based on a DES electrolyte, which in this case is composed of sodium bis(trifluoromethanesulfonyl)imide (NaTFSI) and N-methylacetamide (NMA) alongside the electrode active materials poly(2,2,6,6-tetramethylpiperidin-1-yl-oxyl methacrylate) (PTMA) and crosslinked poly(vinylbenzylviologen) (X-PVBV$^{2+}$). The resulting cell shows two voltage plateaus at 1.07 V and 1.58 V and achieves Coulombic efficiencies of 98 %. Surprisingly, the X-PVBV/X-PVBV$^+$ redox couple turned out to be much more stable in NaTFSI : NMA 1 : 6 than the X-PVBV$^+$/X-PVBV$^{2+}$ couple, leading to asymmetric capacity fading during cycling tests

Toll-like receptor stimulation induces higher TNF-alpha secretion in peripheral blood mononuclear cells from patients with hyper IgE syndrome

Hyper IgE syndromes (HIES) are primary immunodeficiency disorders of unknown pathogenesis. Patients are typically affected with `cold' abscesses of the skin, recurrent cyst-forming pneumonia, chronic mucocutaneous candidiasis and other less frequent features such as progressive skeletal abnormalities. Defective signaling in the Toll-like receptor (TLR) pathways has been suggested as a responsible pathologic mechanism, however, in previous reports, 10 patients revealed no defect in inflammatory cytokine responses to different TLR ligands. Here, we report the increase in pro-inflammatory cytokines TNF-alpha and IL-8, following TLR2 and TLR4 stimulation in a larger cohort of 25 additional patients with HIES, and provide a meta-analysis of the TLR data in HIES. Copyright (C) 2008 S. Karger AG, Basel

LUVMI: an innovative payload for the sampling of volatiles at the Lunar poles

The ISECG identifies one of the first exploration steps as in situ investigations of the moon or asteroids. Europe is developing payload concepts for drilling and sample analysis, a contribution to a 250kg rover as well as for sample return. To achieve these missions, ESA depends on international partnerships. Such missions will be seldom, expensive and the drill/sample site selected will be based on observations from orbit not calibrated with ground truth data. Many of the international science community’s objectives can be met at lower cost, or the chances of mission success improved and the quality of the science increased by making use of an innovative, low mass, mobile robotic payload following the LEAG recommendations. LUVMI provides a smart, low mass, innovative, modular mobile payload comprising surface and subsurface sensing with an in-situ sampling technology capable of depth-resolved extraction of volatiles, combined with a volatile analyser (mass spectrometer) capable of identifying the chemical composition of the most important volatiles. This will allow LUVMI to: traverse the lunar surface prospecting for volatiles; sample subsurface up to a depth of 10 cm (with a goal of 20 cm); extract water and other loosely bound volatiles; identify the chemical species extracted; access and sample permanently shadowed regions (PSR). The main innovation of LUVMI is to develop an in situ sampling technology capable of depth-resolved extraction of volatiles, and then to package within this tool, the analyser itself, so as to maximise transfer efficiency and minimise sample handling and its attendant mass requirements and risk of sample alteration. By building on national, EC and ESA funded research and developments, this project will develop to TRL6 instruments that together form a smart modular mobile payload that could be flight ready in 2020. The LUVMI sampling instrument will be tested in a highly representative environment including thermal, vacuum and regolith simulant and the integrated payload demonstrated in a representative environment

Data-driven Bayesian inference of turbulence model closure coefficients incorporating epistemic uncertainty

We introduce a framework for statistical inference of the closure coefficients using machine learning methods. The objective of this framework is to quantify the epistemic uncertainty associated with the closure model by using experimental data via Bayesian statistics. The framework is tailored towards cases for which a limited amount of experimental data is available. It consists of two components. First, by treating all latent variables (non-observed variables) in the model as stochastic variables, all sources of uncertainty of the probabilistic closure model are quantified by a fully Bayesian approach. The probabilistic model is defined to consist of the closure coefficients as parameters and other parameters incorporating noise. Then, the uncertainty associated with the closure coefficients is extracted from the overall uncertainty by considering the noise being zero. The overall uncertainty is rigorously evaluated by using Markov-Chain Monte Carlo sampling assisted by surrogate models. We apply the framework to the Spalart-Allmars one-equation turbulence model. Two test cases are considered, including an industrially relevant full aircraft model at transonic flow conditions, the Airbus XRF1. Eventually, we demonstrate that epistemic uncertainties in the closure coefficients result into uncertainties in flow quantities of interest which are prominent around, and downstream, of the shock occurring over the XRF1 wing. This data-driven approach could help to enhance the predictive capabilities of computational fluid dynamics (CFD) in terms of reliable turbulence modeling at extremes of the flight envelope if measured data is available, which is important in the context of robust design and towards virtual aircraft certification. The plentiful amount of information about the uncertainties could also assist when it comes to estimating the influence of the measured data on the inferred model coefficients. Finally, the developed framework is flexible and can be applied to different test cases and to various turbulence models

Spectroscopic Discovery of the Broad-Lined Type Ic Supernova 2010bh Associated with the Low-Redshift GRB 100316D

We present the spectroscopic discovery of a broad-lined Type Ic supernova (SN 2010bh) associated with the nearby long-duration gamma-ray burst (GRB) 100316D. At z = 0.0593, this is the third-nearest GRB-SN. Nightly optical spectra obtained with the Magellan telescopes during the first week after explosion reveal the gradual emergence of very broad spectral features superposed on a blue continuum. The supernova features are typical of broad-lined SNe Ic and are generally consistent with previous supernovae associated with low-redshift GRBs. However, the inferred velocities of SN 2010bh at 21 days after explosion are a factor of ~2 times larger than those of the prototypical SN 1998bw at similar epochs, with v ~ 26,000 km/s, indicating a larger explosion energy or a different ejecta structure. A near-infrared spectrum taken 13.8 days after explosion shows no strong evidence for He I at 1.083 microns, implying that the progenitor was largely stripped of its helium envelope. The host galaxy is of low luminosity (M_R ~ -18.5 mag) and low metallicity (Z < 0.4 Z_solar), similar to the hosts of other low-redshift GRB-SNe.Comment: 6 pages, 4 figures, 1 table, submitted to ApJ Letter