A High-Resolution Multiband Survey of Westerlund 2 With the Hubble Space Telescope I: Is the Massive Star Cluster Double?

We present first results from a high resolution multi-band survey of the Westerlund 2 region with the Hubble Space Telescope. Specifically, we imaged Westerlund 2 with the Advanced Camera for Surveys through the $F555W$, $F814W$, and $F658N$ filters and with the Wide Field Camera 3 in the $F125W$, $F160W$, and $F128N$ filters. We derive the first high resolution pixel-to-pixel map of the color excess $E(B-V)_g$ of the gas associated with the cluster, combining the H$\alpha$ ($F658N$) and Pa$\beta$ ($F128N$) line observations. We demonstrate that, as expected, the region is affected by significant differential reddening with a median of $E(B-V)_g=1.87$~mag. After separating the populations of cluster members and foreground contaminants using a $(F814W-F160W)$ vs. $F814W$ color-magnitude diagram, we identify a pronounced pre-main-sequence population in Westerlund 2 showing a distinct turn-on. After dereddening each star of Westerlund 2 individually in the color-magnitude diagram we find via over-plotting PARSEC isochrones that the distance is in good agreement with the literature value of $\sim4.16 \pm 0.33$~kpc. With zero-age-main-sequence fitting to two-color-diagrams, we derive a value of total to selective extinction of $R_V=3.95 \pm 0.135$. A spatial density map of the stellar content reveals that the cluster might be composed of two clumps. We estimate the same age of 0.5-2.0 Myr for both clumps. While the two clumps appear to be coeval, the northern clump shows a $\sim 20 \%$ lower stellar surface density.Comment: 24 pages, 27 figures, 7 tables; Accepted for publication to The Astronomical Journa

Nerve growth factor and receptor expression in rheumatoid arthritis and spondyloarthritis

Introduction We previously described the presence of nerve growth factor receptors in the inflamed synovial compartment. Here we investigated the presence of the corresponding nerve growth factors, with special focus on nerve growth factor (NGF). Methods mRNA expression levels of four ligands (NGF, brain derived growth factor (BDNF), neurotrophin (NT)-3, NT-4) and their four corresponding receptors (tyrosine kinase (trk) A, trkB, trkC, NGFRp75) were determined in the synovial fluid (SF) cells of 9 patients with rheumatoid arthritis (RA) and 16 with spondyloarthritis (SpA) and compared with 7 osteoarthritis (OA) patients. NGF was also determined in synovial tissue (ST) biopsies of 10 RA and 10 SpA patients. The production of NGF by monocytes and lymphocytes was assessed by flow cytometry of SF cells, synovial tissue derived fibroblast-like synoviocytes (FLS) were assessed by ELISA on culture supernatant. Results SF cell analysis revealed a clear BDNF and NGF mRNA expression, with significantly higher NGF expression in RA and SpA patients than in the OA group. NGF expression was higher in ST samples of RA as compared to SpA. Using intracellular FACS analysis, we could demonstrate the presence of the NGF protein in the two inflammatory arthritis groups on both CD3+ T lymphocytes and CD14+ cells, i.e. monocytes/macrophages, whereas cultured FLS did not produce NGF in vitro. Conclusions Neurotrophins and especially NGF are expressed in the synovial fluid and tissue of patients with peripheral synovitis. The presence of neurotrophins as well as their receptors, in particular the NGF/trkA-p75 axis in peripheral synovitis warrants further functional investigation of their active involvement in chronic inflammatory arthriti

Relationship between atomic structure and excellent glass forming ability in Pd42.5Ni7.5Cu30P20 metallic glass

International audienceTo understand the relation of the glass-forming ability (GFA) to the local atomic configurations of a PdNiCuP (PNCP) metallic glass having the best GFA at present, the local structures were investigated by combining data obtained from anomalous X-ray scattering, X-ray and neutron diffraction, and applying reverse Monte Carlo modeling. By comparing the results of PNCP with PdNiP (PNP) and PdCuP (PCP) having a slightly and much worse GFAs, respectively, characteristic features were observed in the hyper-ordered atomic structures. Firstly, the concentration inhomogeneity of Ni/Cu in PNCP is larger than that of Ni in PNP and Cu in PCP. Secondly, a Voronoi tessellation showed that the fraction of pure icosahedral arrangements around the Cu atoms increases significantly in PNCP by adding icosahedral-preferred Ni atoms in PCP. Finally, a persistent homology (PH) analysis reveals the largest intermediate-size Cu PH rings in PNCP among the PH rings in these Pd-based BMGs. The structural heterogeneity for the excellent GFA of PNCP would be considered by an incompatible mixture of specific Pd-P configurations and icosahedral clusters around the secondary Ni and Cu metals

Unital Quantum Channels - Convex Structure and Revivals of Birkhoff's Theorem

The set of doubly-stochastic quantum channels and its subset of mixtures of unitaries are investigated. We provide a detailed analysis of their structure together with computable criteria for the separation of the two sets. When applied to O(d)-covariant channels this leads to a complete characterization and reveals a remarkable feature: instances of channels which are not in the convex hull of unitaries can return to it when either taking finitely many copies of them or supplementing with a completely depolarizing channel. In these scenarios this implies that a channel whose noise initially resists any environment-assisted attempt of correction can become perfectly correctable.Comment: 31 page

Partial structure investigation of the traditional bulk metallic glass Pd40Ni40 P20

Local structures of Pd 40 Ni 40 P 20 bulk metallic glass were investigated by combining anomalous x-ray scattering close to the Pd and Ni K absorption edges, x-ray diffraction, neutron diffraction, and reverse Monte Carlo modeling, from which partial structure factors S i j (Q) and partial pair distribution functions g i j (r) as well as threedimensional atomic configurations were carefully obtained around the constituent elements. A disagreement is found in the local structures with an ab initio molecular dynamics simulation by Guan et al., i.e., the existence of the P-P nearest-neighboring configurations is clarified in the present experimental result. From the Voronoi tessellation analysis, a preference of the pure icosahedral configurations is observed around the Ni atoms, whereas the local configurations around the Pd and P atoms are rather distorted icosahedra. A persistent homology analysis was carried out to identify meaningful shape characteristics of the intermediate-range atomic configuration of large rings

Performance of the CMS Cathode Strip Chambers with Cosmic Rays

The Cathode Strip Chambers (CSCs) constitute the primary muon tracking device in the CMS endcaps. Their performance has been evaluated using data taken during a cosmic ray run in fall 2008. Measured noise levels are low, with the number of noisy channels well below 1%. Coordinate resolution was measured for all types of chambers, and fall in the range 47 microns to 243 microns. The efficiencies for local charged track triggers, for hit and for segments reconstruction were measured, and are above 99%. The timing resolution per layer is approximately 5 ns