OVI, NV and CIV in the Galactic Halo: II. Velocity-Resolved Observations with Hubble and FUSE

We present a survey of NV and OVI (and where available CIV) in the Galactic halo, using data from the Far Ultraviolet Spectroscopic Explorer (FUSE) and the Hubble Space Telescope (HST) along 34 sightlines. These ions are usually produced in nonequilibrium processes such as shocks, evaporative interfaces, or rapidly cooling gas, and thus trace the dynamics of the interstellar medium. Searching for global trends in integrated and velocity-resolved column density ratios, we find large variations in most measures, with some evidence for a systematic trend of higher ionization (lower NV/OVI column density ratio) at larger positive line-of-sight velocities. The slopes of log[N(NV)/N(OVI)] per unit velocity range from -0.015 to +0.005, with a mean of -0.0032+/-0.0022(r)+/-0.0014(sys) dex/(km/s). We compare this dataset with models of velocity-resolved high-ion signatures of several common physical structures. The dispersion of the ratios, OVI/NV/CIV, supports the growing belief that no single model can account for hot halo gas, and in fact some models predict much stronger trends than are observed. It is important to understand the signatures of different physical structures to interpret specific lines of sight and future global surveys.Comment: ApJ in press 43 pages, 22 fig

Speeding up Simplification of Polygonal Curves using Nested Approximations

We develop a multiresolution approach to the problem of polygonal curve approximation. We show theoretically and experimentally that, if the simplification algorithm A used between any two successive levels of resolution satisfies some conditions, the multiresolution algorithm MR will have a complexity lower than the complexity of A. In particular, we show that if A has a O(N2/K) complexity (the complexity of a reduced search dynamic solution approach), where N and K are respectively the initial and the final number of segments, the complexity of MR is in O(N).We experimentally compare the outcomes of MR with those of the optimal "full search" dynamic programming solution and of classical merge and split approaches. The experimental evaluations confirm the theoretical derivations and show that the proposed approach evaluated on 2D coastal maps either shows a lower complexity or provides polygonal approximations closer to the initial curves.Comment: 12 pages + figure

Cold Dust but Warm Gas in the Unusual Elliptical Galaxy NGC 4125

Data from the Herschel Space Observatory have revealed an unusual elliptical galaxy, NGC 4125, which has strong and extended submillimeter emission from cold dust but only very strict upper limits to its CO and Hi emission. Depending on the dust emissivity, the total dust mass is 2-5 x 10(6) M-circle dot. While the neutral gas-to-dust mass ratio is extremely low (= 10(4) K faster than the dust is evaporated. If galaxies like NGC 4125, where the far-infrared emission does not trace neutral gas in the usual manner, are common at higher redshift, this could have significant implications for our understanding of high redshift galaxies and galaxy evolution.Canadian Space AgencyNatural Sciences and Engineering Research Council of CanadaAgenzia Spaziale Italiana (ASI) I/005/11/0BMVIT (Austria)ESA-PRODEX (Belgium)CEA/CNES (France)DLR (Germany)ASI/INAF (Italy)CICYT/MCYT (Spain)CSA (Canada)NAOC (China)CEA, (France)CNES (France)CNRS (France)ASI (Italy)MCINN (Spain)SNSB (Sweden)STFC (UK)NASA (USA)National Aeronautics and Space AdministrationAstronom

ALMA Resolves 30 Doradus: Sub-parsec Molecular Cloud Structure Near the Closest Super-Star Cluster

We present ALMA observations of 30 Doradus -- the highest resolution view of molecular gas in an extragalactic star formation region to date (~0.4pc x 0.6pc). The 30Dor-10 cloud north of R136 was mapped in 12CO 2-1, 13CO 2-1, C18O 2-1, 1.3mm continuum, the H30alpha recombination line, and two H2CO 3-2 transitions. Most 12CO emission is associated with small filaments and clumps (<1pc, ~1000 Msun at the current resolution). Some clumps are associated with protostars, including "pillars of creation" photoablated by intense radiation from R136. Emission from molecular clouds is often analyzed by decomposition into approximately beam-sized clumps. Such clumps in 30 Doradus follow similar trends in size, linewidth, and surface density to Milky Way clumps. The 30 Doradus clumps have somewhat larger linewidths for a given size than predicted by Larson's scaling relation, consistent with pressure confinement. They extend to higher surface density at a given size and linewidth compared to clouds studied at 10pc resolution. These trends are also true of clumps in Galactic infrared-dark clouds; higher resolution observations of both environments are required. Consistency of clump masses calculated from dust continuum, CO, and the virial theorem reveals that the CO abundance in 30 Doradus clumps is not significantly different from the LMC mean, but the dust abundance may be reduced by ~2. There are no strong trends in clump properties with distance from R136; dense clumps are not strongly affected by the external radiation field, but there is a modest trend towards lower dense clump filling fraction deeper in the cloud.Comment: accepted to Ap

The Three Pillars of Natural Product Dereplication. Alkaloids from the Bulbs of Urceolina peruviana (C. Presl) J.F. Macbr. as a Preliminary Test Case

The role and importance of the identification of natural products are discussed in the perspective of the study of secondary metabolites. The rapid identification of already reported compounds, or structural dereplication, is recognized as a key element in natural product chemistry. The biological taxonomy of metabolite producing organisms, the knowledge of metabolite molecular structures, and the availability of metabolite spectroscopic signatures are considered as the three pillars of structural dereplication. The role and the construction of databases is illustrated by references to the KNApSAcK, UNPD, CSEARCH, and COCONUT databases, and by the importance of calculated taxonomic and spectroscopic data as substitutes for missing or lost original ones. Two NMR-based tools, the PNMRNP database that derives from UNPD, and KnapsackSearch, a database generator that provides taxonomically focused libraries of compounds, are proposed to the community of natural product chemists. The study of the alkaloids from Urceolina peruviana, a plant from the Andes used in traditional medicine for antibacterial and anticancer actions, has given the opportunity to test different approaches to dereplication, favoring the use of publicly available data sources

Spitzer View of Massive Star Formation in the Tidally Stripped Magellanic Bridge

The Magellanic Bridge is the nearest low-metallicity, tidally stripped environment, offering a unique high-resolution view of physical conditions in merging and forming galaxies. In this paper we present analysis of candidate massive young stellar objects (YSOs), i.e., {\it in situ, current} massive star formation (MSF) in the Bridge using {\it Spitzer} mid-IR and complementary optical and near-IR photometry. While we definitely find YSOs in the Bridge, the most massive are $\sim10 M_\odot$, $\ll45 M_\odot$ found in the Large Magellanic Cloud (LMC). The intensity of MSF in the Bridge also appears decreasing, as the most massive YSOs are less massive than those formed in the past. To investigate environmental effects on MSF, we have compared properties of massive YSOs in the Bridge to those in the LMC. First, YSOs in the Bridge are apparently less embedded than in the LMC: 81% of Bridge YSOs show optical counterparts, compared to only 56% of LMC sources with the same range of mass, circumstellar dust mass, and line-of-sight extinction. Circumstellar envelopes are evidently more porous or clumpy in the Bridge's low-metallicity environment. Second, we have used whole samples of YSOs in the LMC and the Bridge to estimate the probability of finding YSOs at a given \hi\ column density, N(HI). We found that the LMC has $\sim3\times$ higher probability than the Bridge for N(HI) $>10\times10^{20}$ cm$^{-2}$, but the trend reverses at lower N(HI). Investigating whether this lower efficiency relative to HI is due to less efficient molecular cloud formation, or less efficient cloud collapse, or both, will require sensitive molecular gas observations.Comment: 41 pages, 20 figures, 6 tables; accepted for publication in ApJ; several figures are in low resolution due to the size limit here and a high resolution version can be downloaded via http://www.astro.virginia.edu/~cc5ye/ms_bridge20140215.pd

PACS photometry of the Herschel Reference Survey - Far-infrared/sub-millimeter colours as tracers of dust properties in nearby galaxies

We present Herschel/PACS 100 and 160 micron integrated photometry for the 323 galaxies in the Herschel Reference Survey (HRS), a K-band-, volume-limited sample of galaxies in the local Universe. Once combined with the Herschel/SPIRE observations already available, these data make the HRS the largest representative sample of nearby galaxies with homogeneous coverage across the 100-500 micron wavelength range. In this paper, we take advantage of this unique dataset to investigate the properties and shape of the far-infrared/sub-millimeter spectral energy distribution in nearby galaxies. We show that, in the stellar mass range covered by the HRS (8<log(M*/Msun)<12), the far-infrared/sub-millimeter colours are inconsistent with a single modified black-body having the same dust emissivity index beta for all galaxies. In particular, either beta decreases, or multiple temperature components are needed, when moving from metal-rich/gas-poor to metal-poor/gas-rich galaxies. We thus investigate how the dust temperature and mass obtained from a single modified black-body depend on the assumptions made on beta. We show that, while the correlations between dust temperature, galaxy structure and star formation rate are strongly model dependent, the dust mass scaling relations are much more reliable, and variations of beta only change the strength of the observed trends.Comment: 26 pages, 8 figures, 2 tables. Accepted for publication in MNRA

Inhibition of hepadnaviral replication by polyethylenimine-based intravenous delivery of antisense phosphodiester oligodeoxynucleotides to the liver

Antisense oligodeoxynucleotides (ODNs) appear as attractive anti-hepatitis B virus (HBV) agents. We investigated in vivo, in the duck HBV (DHBV) infection model, whether linear polyethylenimine (lPEI)-based intravenous delivery of the natural antisense phosphodiester ODNs (O-ODNs) can prevent their degradation and allow viral replication inhibition in the liver. DHBV-infected Pekin ducklings were injected with antisense O-ODNs covering the initiation codon of the DHBV large envelope protein, either in free form (O-ODN-AS2) or coupled to lPEI (lPEI/O-ODN-AS2). Following optimization of lPEI/O-ODN complex formulation, complete O-ODN condensation into a homogenous population of small (20–60 nm) spherical particles was achieved. Flow cytometry analysis showed that lPEI-mediated transfer allowed the intrahepatic delivery of lPEI/O-ODN-AS2 to increase three-fold as compared with the O-ODN-AS2. Following 9-day therapy the intrahepatic levels of both DHBV DNA and RNA were significantly decreased in the lPEI/O-ODN-AS2-treated group as compared with the O-ODN-AS2-treated, control lPEI/O-ODN-treated, and untreated controls. In addition, inhibition of intrahepatic viral replication by lPEI/O-ODN-AS2 was not associated with toxicity and was comparable with that induced by the phosphorothioate S-ODN-AS2 at a five-fold higher dose. Taken together, our results demonstrate that phosphodiester antisense lPEI/O-ODN complexes specifically inhibit hepadnaviral replication. Therefore we provide here the first in vivo evidence that intravenous treatment with antisense phosphodiester ODNs coupled to lPEI can selectively block a viral disease-causing gene in the liver