3,288 research outputs found
Holocene-Neogene volcanism in northeastern Australia: chronology and eruption history
Quaternary and late Neogene volcanism is widespread in northeastern Australia, producing at least 397 eruptions covering more than 20,000 km2, including at least 20 flows over 50 km long. Despite this abundance of young volcanism, before this study numerous eruptions had tentative ages or were undated, and the area requires a comprehensive evaluation of eruption patterns through time. To help address these issues we applied multi-collector ARGUS-V 40Ar/39Ar geochronology to determine the age of four of the younger extensive flows: Undara (160 km long, 189 ± 4/4 ka; 2Ï, with full analytical/external uncertainties), Murronga (40 km long, 153 ± 5/5 ka), Toomba (120 km long, 21 ± 3/3 ka), and Kinrara (55 km long, 7 ± 2/2 ka). Verbal traditions of the Gugu Badhun Aboriginal people contain features that may potentially describe the eruption of Kinrara. If the traditions do record this eruption, they would have been passed down for 230 ± 70 generations â a period of time exceeding the earliest written historical records. To further examine north Queensland volcanism through time we compiled a database of 337 ages, including 179 previously unpublished K-Ar and radiocarbon results. The compiled ages demonstrate that volcanic activity has occurred without major time breaks since at least 9 Ma. The greatest frequency of eruptions occurred in the last 2 Ma, with an average recurrence interval of <10â22 ka between eruptions. Activity was at times likely more frequent than these calculations indicate, as the geochronologic dataset is incomplete, with undated eruptions, and intraplate volcanism is often episodic. The duration, frequency, and youthfulness of activity indicate that north Queensland volcanism should be considered as potentially still active, and there are now two confirmed areas of Holocene volcanism in eastern Australia â one at each end of the continent. More broadly, our data provides another example of 40Ar/39Ar geochronology applied to Holocene and latest Pleistocene mafic eruptions, further demonstrating that this method has the ability to examine eruptions and hazards at the youngest volcanoes on Earth
Evaluation of Six Atmospheric Reanalyses over Arctic Sea Ice from Winter to Early Summer
© Copyright 19 June 2019 American Meteorological Society (AMS). Permission to use figures, tables, and brief excerpts from this work in scientific and educational works is hereby granted provided that the source is acknowledged. Any use of material in this work that is determined to be âfair useâ under Section 107 of the U.S. Copyright Act or that satisfies the conditions specified in Section 108 of the U.S. Copyright Act (17 USC §108) does not require the AMSâs permission. Republication, systematic reproduction, posting in electronic form, such as on a website or in a searchable database, or other uses of this material, except as exempted by the above statement, requires written permission or a license from the AMS. All AMS journals and monograph publications are registered with the Copyright Clearance Center (http://www.copyright.com). Questions about permission to use materials for which AMS holds the copyright can also be directed to [email protected]. Additional details are provided in the AMS Copyright Policy statement, available on the AMS website (http://www.ametsoc.org/CopyrightInformation).This study evaluates the performance of six atmospheric reanalyses (ERA-Interim, ERA5, JRA-55, CFSv2, MERRA-2, and ASRv2) over Arctic sea ice from winter to early summer. The reanalyses are evaluated using observations from the Norwegian Young Sea Ice campaign (N-ICE2015), a 5-month ice drift in pack ice north of Svalbard. N-ICE2015 observations include surface meteorology, vertical profiles from radiosondes, as well as radiative and turbulent heat fluxes. The reanalyses simulate surface analysis variables well throughout the campaign, but have difficulties with most forecast variables. Wintertime (JanuaryâMarch) correlation coefficients between the reanalyses and observations are above 0.90 for the surface pressure, 2-m temperature, total column water vapor, and downward longwave flux. However, all reanalyses have a positive wintertime 2-m temperature bias, ranging from 1° to 4°C, and negative (i.e., upward) net longwave bias of 3â19 W mâ2. These biases are associated with poorly represented surface inversions and are largest during cold-stable periods. Notably, the recent ERA5 and ASRv2 datasets have some of the largest temperature and net longwave biases, respectively. During spring (AprilâMay), reanalyses fail to simulate observed persistent cloud layers. Therefore they overestimate the net shortwave flux (5â79 W mâ2) and underestimate the net longwave flux (8â38 W mâ2). Promisingly, ERA5 provides the best estimates of downward radiative fluxes in spring and summer, suggesting improved forecasting of Arctic cloud cover. All reanalyses exhibit large negative (upward) residual heat flux biases during winter, and positive (downward) biases during summer. Turbulent heat fluxes over sea ice are simulated poorly in all seasons
Pharmacokinetics and Safety of Micafungin in Infants Supported With Extracorporeal Membrane Oxygenation
Candida is a leading cause of infection in infants on extracorporeal membrane oxygenation (ECMO). Optimal micafungin dosing is unknown in this population because ECMO can alter drug pharmacokinetics (PK)
A New Spiral Arm of the Galaxy: The Far 3-Kpc Arm
We report the detection in CO of the far-side counterpart of the well-known
expanding 3-Kpc Arm in the central region of the Galaxy. In a CO
longitude-velocity map at b = 0 deg the Far 3-Kpc Arm can be followed over at
least 20 deg of Galactic longitude as a faint lane at positive velocities
running parallel to the Near Arm. The Far Arm crosses l = 0 deg at +56 km/s,
quite symmetric with the -53 km/s expansion velocity of the Near Arm. In
addition to their symmetry in longitude and velocity, we find that the two arms
have linewidths (~21 km/s), linear scale heights (~103 pc FWHM), and H2 masses
per unit length (~4.3 x 10^6 Mo/kpc) that agree to 26% or better. Guided by the
CO, we have also identified the Far Arm in high-resolution 21 cm data and find,
subject to the poorly known CO-to-H2 ratio in these objects, that both arms are
predominately molecular by a factor of 3-4. The detection of these symmetric
expanding arms provides strong support for the existence of a bar at the center
of our Galaxy and should allow better determination of the bar's physical
properties.Comment: ApJ Letters, accepted 9 July 0
Exposure Matching of Pediatric Anti-infective Drugs: Review of Drugs Submitted to the Food and Drug Administration for Pediatric Approval
Over the last decade, few novel antibiotics have been approved by the Food and Drug Administration (FDA) for pediatric use. For most anti-infective agents, including antibiotics, extrapolation of efficacy from adults to children is possible if the disease and therapeutic exposures are similar between the 2 populations. This approach reduces the number of studies required in children, but relies heavily on exposure matching between children and adults. Failures in exposure matching can lead to delays in pediatric approvals of new anti-infective agents. We sought to determine the extent of exposure matching, defined by a comparison of area under the concentration-time curve, between children and adults, for anti-infective drug products submitted to the FDA for approval
GLIMPSE: I. A SIRTF Legacy Project to Map the Inner Galaxy
GLIMPSE (Galactic Legacy Infrared Mid-Plane Survey Extraordinaire), a SIRTF
Legacy Science Program, will be a fully sampled, confusion-limited infrared
survey of the inner two-thirds of the Galactic disk with a pixel resolution of
\~1.2" using the Infrared Array Camera (IRAC) at 3.6, 4.5, 5.8, and 8.0
microns. The survey will cover Galactic latitudes |b| <1 degree and longitudes
|l|=10 to 65 degrees (both sides of the Galactic center). The survey area
contains the outer ends of the Galactic bar, the Galactic molecular ring, and
the inner spiral arms. The GLIMPSE team will process these data to produce a
point source catalog, a point source data archive, and a set of mosaicked
images. We summarize our observing strategy, give details of our data products,
and summarize some of the principal science questions that will be addressed
using GLIMPSE data. Up-to-date documentation, survey progress, and information
on complementary datasets are available on the GLIMPSE web site:
www.astro.wisc.edu/glimpse.Comment: Description of GLIMPSE, a SIRTF Legacy project (Aug 2003 PASP, in
press). Paper with full res.color figures at
http://www.astro.wisc.edu/glimpse/glimpsepubs.htm
The Mid-Infrared Colours of Galactic Bulge, Disk and Magellanic Planetary Nebulae
We present mid-infrared (MIR) photometry for 367 Galactic disk, bulge and
Large Magellanic Cloud (LMC) planetary nebulae, determined using GLIMPSE II and
SAGE data acquired using the Spitzer Space Telescope. This has permitted us to
make a comparison between the luminosity functions of bulge and LMC planetary
nebulae, and between the MIR colours of all three categories of source. It is
determined that whilst the 3.6 microns luminosity function of the LMC and bulge
sources are likely to be closely similar, the [3.6]-[5.8] and [5.8]-[8-0]
indices of LMC nebulae are different from those of their disk and bulge
counterparts. This may arise because of enhanced 6.2 microns PAH emission
within the LMC sources, and/or as a result of differences between the spectra
of LMC PNe and those of their Galactic counterparts. We also determine that the
more evolved disk sources listed in the MASH catalogues of Parker et al. and
Miszalski et al. (2008) have similar colours to those of the less evolved (and
higher surface brightness) sources in the catalogue of Acker et al. (1992); a
result which appears at variance with previous studies of these sources.Comment: 14 pages, 9 figures, Publicated in MNRAS. 58 pages in arXi
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