Persistent circulating platelet and endothelial derived microparticle signature may explain on-going pro-thrombogenicity after acute coronary syndrome

Aims: Microparticles (MPs) are submicron vesicles, released from activated, and apoptotic cells. MPs are elevated in the circulation of patients with coronary artery disease (CAD) and have pro-thrombotic potential. However, limited data exists on MP signature over time following an acute coronary event. / Methods & results: Circulating total annexin v + (Anv+) MPs of endothelial (EMP), platelet (PMP), monocyte (MMP), neutrophil (NMP) and smooth muscle cell (SMMP) origin were quantified by flow cytometry. 13 patients with acute coronary syndrome (ACS) were prospectively enrolled and 12 patients with stable angina (SA) were included as a comparator group. A panel of MP was measured at baseline, after percutaneous coronary intervention (PCI) and at days 1, 7, 30 and 6 months. Intra & inter group comparison was made between various time points. MP mediated thrombin generation was measured by recording lag phase, velocity index, peak thrombin and endogenous thrombin potential at these time points and compared with healthy controls. The total AnV+ MP levels were similar in ACS and SA groups at baseline, peaked immediately after PCI and were at their lowest on day 1. PMP & EMP levels remained significantly elevated in ACS patients at 6 months when compared to SA. No such difference was noted with NMP, MMP and SMMP. Patients with coronary artery disease showed abnormal thrombograms when compared to controls. Peak thrombin (nano moles) was significantly higher in CAD when compared to controls (254 IQR [226, 239] in ACS, 255 IQR [219, 328] in SA and 132 IQR [57, 252] in controls; p = 0.006). Differences in thrombin generation between ACS and SA were not significant (p = 1). Furthermore, thrombin parameters remained abnormal in ACS & SA patients at 6 months. / Conclusions: Total MP and individual MP phenotypes were significantly elevated after PCI reflecting endothelial injury. Elevated PMP and EMP levels at 6 months in ACS patients is suggestive of on-going inflammation, endothelial injury and may explain on-going pro-thrombogenicity seen up to 6 months after ACS despite dual antiplatelet therapy

OH (1720 MHz) Masers: A Multiwavelength Study of the Interaction between the W51C Supernova Remnant and the W51B Star Forming Region

We present a comprehensive view of the W51B HII region complex and the W51C supernova remnant (SNR) using new radio observations from the VLA, VLBA, MERLIN, JCMT, and CSO along with archival data from Spitzer, ROSAT, ASCA, and Chandra. Our VLA data include the first 400 cm (74 MHz) continuum image of W51 at high resolution (88 arcsec). The 400 cm image shows non-thermal emission surrounding the G49.2-0.3 HII region, and a compact source of non-thermal emission (W51B_NT) coincident with the previously-identified OH (1720 MHz) maser spots, non-thermal 21 and 90 cm emission, and a hard X-ray source. W51B_NT falls within the region of high likelihood for the position of TeV gamma-ray emission. Using the VLBA three OH (1720 MHz) maser spots are detected in the vicinity of W51B_NT with sizes of 60 to 300 AU and Zeeman effect magnetic field strengths of 1.5 to 2.2 mG. The multiwavelength data demonstrate that the northern end of the W51B HII region complex has been partly enveloped by the advancing W51C SNR and this interaction explains the presence of W51B_NT and the OH masers. This interaction also appears in the thermal molecular gas which partially encircles W51B_NT and exhibits narrow pre-shock (DeltaV 5 km/s) and broad post-shock (DeltaV 20 km/s) velocity components. RADEX radiative transfer modeling of these two components yield physical conditions consistent with the passage of a non-dissociative C-type shock. Confirmation of the W51B/W51C interaction provides additional evidence in favor of this region being one of the best candidates for hadronic particle acceleration known thus far.Comment: Accepted to Ap

Impedance spectroscopy study of SrTiO3 pulse laser deposited photoelectrodes

Strontium titanate (STO) is an oxide that has found application in several technological areas and is a candidate electrode for photoelectrochemical cells (PECs). In this study, STO thin films were prepared via pulsed laser deposition to function as PEC electrodes. Effects of post-deposition annealing in a reducing environment on the photocatalytic activity of these electrodes are characterized by measurements of optical and electrochemical properties of the films. These observations are used to obtain insight into how the crystal and electronic properties of these electrodes are affected by the annealing process. Low annealing temperatures produce non-crystalline STO films that exhibit low photocatalytic activity. Annealing at 500 °C and higher allowed the formation of crystalline STO, which showed substantially higher ultraviolet-driven photocurrent densities. Electrochemical impedance spectroscopy reveals large decreases in charge transfer resistance that is associated with improved performance of these films. Oxygen evolution at these electrodes was confirmed with a rotating ring-disk electrode setup. Porous versions of the STO films were investigated to evaluate the effect larger surface area can have in enhancing the water oxidation performance

G11.92-0.61-MM2 : a bonafide massive prestellar core?

Supported by NSF AAPF (C.J.C., AST-1003134) and ERC (A.V., PALs 320620).Core accretion models of massive star formation require the existence of stable massive starless cores, but robust observational examples of such objects have proven elusive. We report subarcsecond-resolution Submillimeter Array (SMA) 1.3 mm, 1.1 mm, and 0.88 mm and Very Large Array 1.3 cm observations of an excellent massive starless core candidate, G11.92–0.61-MM2, initially identified in the course of studies of GLIMPSE Extended Green Objects (EGOs). Separated by ~7 farcs 2 from the nearby MM1 protostellar hot core, MM2 is a strong, compact dust continuum source (submillimeter spectral index α = 2.6 ± 0.1), but is devoid of star formation indicators. In contrast to MM1, MM2 has no masers, no centimeter continuum, and no (sub)millimeter wavelength line emission in ~24 GHz of bandwidth observed with the SMA, including N2H+(3-2), HCO+(3-2), and HCN(3-2). Additionally, there is no evidence for an outflow driven by MM2. The (sub)millimeter spectral energy distribution of MM2 is best fit with a dust temperature of ~17-19 K and luminosity of ~5-7 L☉. The combined physical properties of MM2, as inferred from its dust continuum emission, are extreme: M ≳ 30 M☉ within a radius 1025 cm–2 and nH_2 >109 cm–3. Comparison of the molecular abundance limits derived from our SMA observations with gas-grain chemical models indicates that extremely dense (n(H) ≫ 108 cm–3), cold (<20 K) conditions are required to explain the lack of observed (sub)millimeter line emission, consistent with the dust continuum results. Our data suggest that G11.92–0.61-MM2 is the best candidate for a bonafide massive prestellar core found to date, and a promising target for future higher-sensitivity observations.Publisher PDFPeer reviewe

The Full Spectrum Galactic Terrarium: MHz to TeV Observations of Various Critters

Multi-wavelength studies at radio, infrared, optical, X-ray, and TeV wavelengths have discovered probable counterparts to many Galactic sources of GeV emission detected by EGRET. These include pulsar wind nebulae, high mass X-ray binaries, and mixed morphology supernova remnants. Here we provide an overview of the observational properties of Galactic sources which emit across 19 orders of magnitude in energy. We also present new observations of several sources.Comment: 4 pages, 5 figures, Proceedings of the The 4th Heidelberg International Symposium on High Energy Gamma-Ray Astronomy, eds. Aharonian, Hofmann, Riege

Digging into NGC 6334I(N): Multiwavelength Imaging of a Massive Protostellar Cluster

We present a high-resolution, multi-wavelength study of the massive protostellar cluster NGC 6334I(N) that combines new spectral line data from the Submillimeter Array (SMA) and VLA with a reanalysis of archival VLA continuum data, 2MASS and Spitzer images. As shown previously, the brightest 1.3 mm source SMA1 contains substructure at subarcsecond resolution, and we report the first detection of SMA1b at 3.6 cm along with a new spatial component at 7 mm (SMA1d). We find SMA1 (aggregate of sources a, b, c, and d) and SMA4 to be comprised of free-free and dust components, while SMA6 shows only dust emission. Our 1.5" resolution 1.3 mm molecular line images reveal substantial hot-core line emission toward SMA1 and to a lesser degree SMA2. We find CH3OH rotation temperatures of 165\pm 9 K and 145\pm 12 K for SMA1 and SMA2, respectively. We estimate a diameter of 1400 AU for the SMA1 hot core emission, encompassing both SMA1b and SMA1d, and speculate that these sources comprise a >800 AU separation binary that may explain the previously-suggested precession of the outflow emanating from the SMA1 region. The LSR velocities of SMA1, SMA2, and SMA4 all differ by 1-2 km/s. Outflow activity from SMA1, SMA2, SMA4, and SMA6 is observed in several molecules including SiO(5--4) and IRAC 4.5 micron emission; 24 micron emission from SMA4 is also detected. Eleven water maser groups are detected, eight of which coincide with SMA1, SMA2, SMA4, and SMA6. We also detect a total of 83 Class I CH3OH 44GHz maser spots which likely result from the combined activity of many outflows. Our observations paint the portrait of multiple young hot cores in a protocluster prior to the stage where its members become visible in the near-infrared.Comment: Accepted to ApJ, 24 pages, a full high resolution version is available at http://www.cv.nrao.edu/~cbrogan/ms.long.pd

Filamentary mass accretion towards the high-mass protobinary system G11.92-0.61 MM2

Funding: S.Z. is funded by the China Scholarship Council-University of St Andrews Scholarship (PhD programmes, No. 201806190010). C.J.C. acknowledges support from the University of St Andrews Restarting Research Funding Scheme (SARRF), which is funded through the SFC grant reference SFC/AN/08/020. J.D.H gratefully acknowledges financial support from the Royal Society (University Research Fellowship; URF\R1\2216.We present deep, sub-arcsecond (∼2000 AU) resolution ALMA 0.82 mm observations of the former high-mass prestellar core candidate G11.92-0.61 MM2, recently shown to be an ~500 AU-separation protobinary. Our observations show that G11.92-0.61 MM2, located in the G11.92-0.61 protocluster, lies on a filamentary structure traced by 0.82 mm continuum and N2H+(4-3) emission. The N2H+(4-3) spectra are multi-peaked, indicative of multiple velocity components along the line of sight. To analyse the gas kinematics, we performed pixel-by-pixel Gaussian decomposition of the N2H+$ spectra using SCOUSEPY and hierarchical clustering of the extracted velocity components using ACORNS. Seventy velocity- and position-coherent clusters (called "trees") are identified in the N2H+-emitting gas, with the 8 largest trees accounting for > 60 per cent  of the fitted velocity components. The primary tree, with ~20 per cent of the fitted velocity components, displays a roughly north-south velocity gradient along the filamentary structure traced by the 0.82 mm continuum. Analysing a ~0.17 pc-long substructure, we interpret its velocity gradient of ~10.5 km s-1pc-1 as tracing filamentary accretion towards MM2 and estimate a mass inflow rate of ~1.8 × 10-4 to 1.2 × 10-3 M⊙ yr-1. Based on the recent detection of a bipolar molecular outflow associated with MM2, accretion onto the protobinary is ongoing, likely fed by the larger-scale filamentary accretion flows. If 50% of the filamentary inflow reaches the protostars, each member of the protobinary would attain a mass of 8 M⊙ within ~1.6 × 105 yr, comparable to the combined timescale of the 70-μm- and mid-infrared-weak phases derived for ATLASGAL-TOP100 massive clumps using chemical clocks.Peer reviewe