5,809 research outputs found
Resolving Gas Flows in the Ultraluminous Starburst IRAS23365+3604 with Keck LGSAO/OSIRIS
Keck OSIRIS/LGSAO observations of the ultraluminous galaxy IRAS~23365+3604
resolve a circumnuclear bar (or irregular disk) of semimajor axis 0.42" (520
pc) in Paschen-alpha emission. The line-of-sight velocity of the ionized gas
increases from the northeast toward the southwest; this gradient is
perpendicular to the photometric major axis of the infrared emission. Two pairs
of bends in the zero-velocity line are detected. The inner bend provides
evidence for gas inflow onto the circumnuclear disk/bar structure. We interpret
the gas kinematics on kiloparsec scales in relation to the molecular gas disk
and multiphase outflow discovered previously. In particular, the fast component
of the outflow (detected previously in line wings) is not detected, adding
support to the conjecture that the fast wind originates well beyond the
nucleus. These data directly show the dynamics of gas inflow and outflow in the
central kiloparsec of a late-stage, gas-rich merger and demonstrate the
potential of integral field spectroscopy to improve our understanding of the
role of gas flows during the growth phase of bulges and supermassive black
holes.Comment: 14 pages with 7 figures accepted to the astrophysical journa
High-efficiency receptor-mediated delivery of small and large (48 kilobase gene constructs using the endosome-disruption activity of defective or chemically inactivated adenovirus particles.
One limit to successful receptor-mediated gene delivery is the exit of the endocytosed material from the endosome. We demonstrate here the delivery of marker genes to tissue culture cells using a modification of the receptor-mediated gene delivery technique that exploits the endosomolytic activity of defective adenovirus particles. In particular, greater than 90% of the transfected-cell population is found to express a beta-galactosidase gene, and, most importantly, this high level of expression can be obtained with psoralen-inactivated virus particles. Furthermore, because the delivered gene is not carried within the genome of the adenovirus particle, the size constraints are relieved, and we can, therefore, show the delivery of a 48-kilobase cosmid DNA molecule
Turbulence and waves over irregularly sloping topography : cruise report - Oceanus 324
This report documents the work of R/V Oceanus cruise 324, which occurred during May of 1998.
This cruise was the field component of the Turbulence and Waves in Irregularly Sloping
Topography (TWIST) program. TWIST was part of the Littoral Internal Wave Initiative (LIW)
supported by the Office of Naval Research.
The objective of TWIST was to sample the background, internal wave and turbulence properties
on the Continental Slope in the Mid-Atlantic Bight. Previous investigations have revealed
strongly enhanced finescale internal wavefields and much more energetic turbulence due to
internal wave breaking above topographic roughness associated with the Mid-Atlantic Ridge. So,
an area of steeply sloping ridges and troughs running perpendicular to the continental slope near
36˚34'N, 74˚39'W was chosen as the site of the observational program due to its topographic
similarity to the Mid-Atlantic Ridge.
Fíve instrument systems were employed to make observations during this cruise: the High
Resolution Profier (HRP), three Moored Profiler (MP) moorings, a Lowered Acoustic Doppler
Current Profiler/Conductivity, Temperature, Depth (LADCP/CTD) rosette, eXpendable Current
Profilers/eXpendable CTD (XCP/XCTD), and finally, the shipboard ADCP. The data from these
instruments (more than 1100 full depth profiles) provide adequate spatial and temporal resolution
to describe the finescale and turbulent processes observed.Funding was provided by the Office of Naval Research under Grant No. N00014-97-1-0087
The LyAlpha Line Profiles of Ultraluminous Infrared Galaxies: Fast Winds and Lyman Continuum Leakage
We present new Hubble Space Telescope Cosmic Origins Spectrograph
far-ultraviolet (far-UV) spectroscopy and Keck Echellete optical spectroscopy
of 11 ultraluminous infrared galaxies (ULIRGs), a rare population of local
galaxies experiencing massive gas inflows, extreme starbursts, and prominent
outflows. We detect H Lyman alpha emission from 8 ULIRGs and the companion to
IRAS09583+4714. In contrast to the P Cygni profiles often seen in galaxy
spectra, the H Lyman alpha profiles exhibit prominent, blueshifted emission out
to Doppler shifts exceeding -1000 km/s in three HII-dominated and two
AGN-dominated ULIRGs. To better understand the role of resonance scattering in
shaping the H Lyman alpha line profiles, we directly compare them to
non-resonant emission lines in optical spectra. We find that the line wings are
already present in the intrinsic nebular spectra, and scattering merely
enhances the wings relative to the line core. The H Lyman alpha attenuation (as
measured in the COS aperture) ranges from that of the far-UV continuum to over
100 times more. A simple radiative transfer model suggests the H Lyman alpha
photons escape through cavities which have low column densities of neutral
hydrogen and become optically thin to the Lyman continuum in the most advanced
mergers. We show that the properties of the highly blueshifted line wings on
the H Lyman alpha and optical emission-line profiles are consistent with
emission from clumps of gas condensing out of a fast, hot wind. The luminosity
of the H Lyman alpha emission increases non-linearly with the ULIRG bolometric
luminosity and represents about 0.1 to 1% of the radiative cooling from the hot
winds in the HII-dominated ULIRGs.Comment: Submitted to Ap
Oxygen-related traps in pentacene thin films: Energetic position and implications for transistor performance
We studied the influence of oxygen on the electronic trap states in a
pentacene thin film. This was done by carrying out gated four-terminal
measurements on thin-film transistors as a function of temperature and without
ever exposing the samples to ambient air. Photooxidation of pentacene is shown
to lead to a peak of trap states centered at 0.28 eV from the mobility edge,
with trap densities of the order of 10(18) cm(-3). These trap states need to be
occupied at first and cause a reduction in the number of free carriers, i.e. a
consistent shift of the density of free holes as a function of gate voltage.
Moreover, the exposure to oxygen reduces the mobility of the charge carriers
above the mobility edge. We correlate the change of these transport parameters
with the change of the essential device parameters, i.e. subthreshold
performance and effective field-effect mobility. This study supports the
assumption of a mobility edge for charge transport, and contributes to a
detailed understanding of an important degradation mechanism of organic
field-effect transistors. Deep traps in an organic field-effect transistor
reduce the effective field-effect mobility by reducing the number of free
carriers and their mobility above the mobility edge.Comment: 13 pages, 14 figures, to be published in Phys. Rev.
Coupling of adenovirus to transferrin-polylysine/DNA complexes greatly enhances receptor-mediated gene delivery and expression of transfected genes.
We are developing efficient methods for gene transfer into tissue culture cells. We have previously shown that coupling of a chimeric adenovirus with polylysine allowed the construction of an adenovirus-polylysine-reporter-gene complex that transferred the transporter gene with great efficiency into HeLa cells. We have now explored simpler, biochemical means for coupling adenovirus to DNA/polylysine complexes and show that such complexes yield virtually 100% transfection in tissue culture cell lines. In these methods adenovirus is coupled to polylysine, either enzymatically through the action of transglutaminase or biochemically by biotinylating adenovirus and streptavidinylating the polylysine moiety. Combination complexes containing DNA, adenovirus-polylysine, and transferrin-polylysine have the capacity to transfer the reporter gene into adenovirus-receptor- and/or transferrin-receptor-rich cells
Advantages of large medical record database for outcomes research: Insights into post‐menopausal hormone therapy
Approximately 25 years ago, our team initiated studies to determine whether outcome results from a large medical record database would yield valid results. We utilized the data in the United Kingdom (UK) General Practice Research Database (GPRD) to replicate the randomized controlled trial (RCT) study result and compared them to confirm the database results. The initial studies compared favorably, but some subsequent studies did not. This prompted development of a new strategy to determine and correct for unrecognized confounding in the database. This strategy divided outcome rates prior to initiation of therapy in the database study (which should include both identified and unidentified confounders) into the outcome rates during the treatment interval. When they differed from Cox‐adjusted results, it reflected unrecognized confounding. We called this strategy Prior Event Rate Ratio (PERR)–adjusted outcome.One of our previously published observational studies replicated the Women’s Health Initiative (WHI) RCT study of hormone therapy in post‐menopausal women. Our study results replicated the WHI RCT results except it did not exhibit an increase in heart attack in contrast to the RCT. Furthermore, we could not evaluate death reliably since our analytic approach to overcome unrecognized confounding does not work for this outcome. In Volume 1, Issue 1 of the Learning Health Systems open access journal, we published a new study (titled “A new method to address unmeasured confounding of mortality in observational studies”) that reported a novel death method, based on our prior methodology, that could analyze unrecognized confounding of the death outcome. This new methodology, termed Post Treatment Event Rate Ratio (PTERR), permitted a reliable examination of mortality in post‐menopausal women undergoing hormone therapy. These results are reported in this manuscript. The study used the data from our previous observational study. It demonstrates that estrogen therapy markedly reduced death in post‐menopausal women.This work also illuminates principles of database construction and correspondingly demonstrates the use of novel methodologies for obtaining valid results, which can be applied to enable learning from such databases. Work to advance such methodologies is essential to advancing the scientific integrity Core Value underpinning learning health systems (LHSs). Indeed, in the absence of such efforts to develop and refine methodologies for learning trustworthy lessons from real‐world data, we risk inadvertently creating mis‐learning systems.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/150513/1/lrh210193.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/150513/2/lrh210193_am.pd
Effects of Mowing and Tebuthiuron on the Nutritional Quality of Wyoming Big Sagebrush
Wyoming big sagebrush (Artemisia tridentata Nutt. ssp. wyomingensis Beetle & Young) is the most abundant and widely distributed subspecies of big sagebrush and has been treated through chemical application, mechanical treatments, and prescribed burning in efforts thought to improve habitat conditions for species such as greater sage-grouse (Centrocercus urophasianus) and mule deer (Odocoileus hemionus). Although the response of structural attributes of sagebrush communities to treatments is well understood, there is a need to identify how treatments influence the quality of sagebrush as winter food for wildlife. Our purpose was to identify how mowing and tebuthiuron treatments influenced dietary quality of Wyoming big sagebrush in central Wyoming. Two study areas were mowed in January and February 2014 and tebuthiuron was applied in two study areas in May 2014. We constructed 6 exclosures in each of these four study areas (24 total), which encompassed 30 m x 30 m areas of treated and untreated sagebrush within each exclosure. Samples of current annual growth were collected from 18 sagebrush plants from treated and 12 plants from control portions of mowing exclosures during November 2013–2015 and tebuthiuron exclosures during November 2014–2015. Samples were analyzed for crude protein and plant secondary metabolites known to influence dietary selection of sagebrush by sage-grouse and other sagebrush occurring herbivores. Our results suggest mowing and tebuthiuron treatments may slightly increase crude protein concentrations directly after treatments without immediate changes in plant secondary metabolites. Slight increases in dietary quality of sagebrush following treatments coupled with potential trade-offs with loss of biomass associated with treatments corroborates previous research that treating Wyoming big sagebrush may have little benefit for sage-grouse and other sagebrush-dependent wildlife. Future work should evaluate not only how treatments influence sage-grouse habitat use and 2 reproductive success, but how treatments influence other wildlife species in fragile sagebrush ecosystems
Research of Magnetizing Roasting of Iron Ore Before Beneficiation and Dephosphorizing
There are quite a lot of iron ore deposits in the world with increased (0.75%) phosphorus content, which is an obstacle to their involving in production. Research of removal of detrimental impurities from such iron ores has a great prospect. On the experimental base of OJSC VNIIMT, it was studied dephosphorizing technology at which after preliminary magnetizing roasting and subsequent dephosphorization of iron ore with aqueous solution of sulfuric acid the least residual phosphorus content in concentrate was observed. Research of influence of temperature and duration of magnetizing roasting on iron content and residual phosphorus content in dephosphorized concentrate was studied. The influence of specific consumption of solid reductant (brown coal) on the quality of magnetite concentrate was also studied. Based on the results of the experiment, the optimal technological parameters of magnetizing roasting of iron ore before beneficiation and subsequentdephosphorization were selected.
Keywords: magnetizing roasting, beneficiation, dephosphorizing, research, rotary furnace, optimal process parameters, iron content, residual phosphorus conten
Differential Uptake of Gold Nanoparticles by 2 Species of Tadpole, the Wood Frog (Lithobates Sylvaticus) and the Bullfrog (Lithobates Catesbeianus)
Engineered nanoparticles are aquatic contaminants of emerging concern that exert ecotoxicological effects on a wide variety of organisms. We exposed cetyltrimethylammonium bromide–capped spherical gold nanoparticles to wood frog and bullfrog tadpoles with conspecifics and in combination with the other species continuously for 21 d, then measured uptake and localization of gold. Wood frog tadpoles alone and in combination with bullfrog tadpoles took up significantly more gold than bullfrogs. Bullfrog tadpoles in combination with wood frogs took up significantly more gold than controls. The rank order of weight-normalized gold uptake was wood frogs in combination \u3e wood frogs alone \u3e bullfrogs in combination \u3e bullfrogs alone \u3e controls. In all gold-exposed groups of tadpoles, gold was concentrated in the anterior region compared with the posterior region of the body. The concentration of gold nanoparticles in the anterior region of wood frogs both alone and in combination with bullfrogs was significantly higher than the corresponding posterior regions. We also measured depuration time of gold in wood frogs. After 21 d in a solution of gold nanoparticles, tadpoles lost \u3e83% of internalized gold when placed in gold-free water for 5 d. After 10 d in gold-free water, tadpoles lost 94% of their gold. After 15 d, gold concentrations were below the level of detection. Our finding of differential uptake between closely related species living in similar habitats with overlapping geographical distributions argues against generalizing toxicological effects of nanoparticles for a large group of organisms based on measurements in only one species
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