1,195 research outputs found
Galaxy Zoo Builder: Four-component Photometric Decomposition of Spiral Galaxies Guided by Citizen Science
Multicomponent modeling of galaxies is a valuable tool in the effort to quantitatively understand galaxy evolution, yet the use of the technique is plagued by issues of convergence, model selection, and parameter degeneracies. These issues limit its application over large samples to the simplest models, with complex models being applied only to very small samples. We attempt to resolve this dilemma of "quantity or quality"by developing a novel framework, built inside the Zooniverse citizen-science platform, to enable the crowdsourcing of model creation for Sloan Digital Sky Survey galaxies. We have applied the method, including a final algorithmic optimization step, on a test sample of 198 galaxies, and examine the robustness of this new method. We also compare it to automated fitting pipelines, demonstrating that it is possible to consistently recover accurate models that either show good agreement with, or improve on, prior work. We conclude that citizen science is a promising technique for modeling images of complex galaxies, and release our catalog of models
The FUSE survey of OVI absorption in and near the Galaxy
We present FUSE observations of OVI absorption in a sample of 100
extragalactic targets and 2 distant halo stars. We describe the details of the
calibration, alignment in velocity, continuum fitting, and manner in which
contaminants were removed (Galactic H2, absorption intrinsic to the background
target and intergalactic Ly-beta lines). We searched for OVI absorption in the
velocity range -1200 to 1200 km/s. With a few exceptions, we only find OVI
between -400 and 400 km/s; the exceptions may be intergalactic OVI. We discuss
the separation of the observed OVI absorption into components associated with
the Galactic halo and components at high-velocity, which are probably located
in the neighborhood of the Galaxy. We describe the measurements of equivalent
width and column density, and we analyze the different contributions to the
errors. We conclude that low-velocity Galactic OVI absorption occurs along all
sightlines - the few non-detections only occur in noisy spectra. We further
show that high-velocity OVI is very common, having equivalent width >65 mAA in
50% of the sightlines and >30 mAA in 70% of the high-quality sightlines. The
high-velocity OVI absorption has velocities relative to the LSR of
+/-(100--330) km/s; there is no correlation between velocity and absorption
strength. We present 50 km/s wide OVI channel maps. These show evidence for the
imprint of Galactic rotation. They also highlight two known HI high-velocity
clouds (complex~C and the Magellanic Stream). The channel maps further show
that OVI at velocities <-200 km/s occurs along all sightlines in the region
l=20-150, b200 km/s occurs along all sightlines
in the region l=180-300, b>20 (abbreviated).Comment: 85 pages, 127 figures, 13 color figures, 3 tables, AASTeX preprint
format. All figures are in PNG format due to space concerns. Bound copies of
manuscript and two accompanying articles are available upon request.
submitted to ApJ
Regional Climate Trends and Scenarios for the U.S. National Climate Assessment Part 4. Climate of the U.S. Great Plains
This document is one of series of regional climate descriptions designed to provide input that can be used in the development of the National Climate Assessment (NCA). As part of a sustained assessment approach, it is intended that these documents will be updated as new and well-vetted model results are available and as new climate scenario needs become clear. It is also hoped that these documents (and associated data and resources) are of direct benefit to decision makers and communities seeking to use this information in developing adaptation plans.
There are nine reports in this series, one each for eight regions defined by the NCA, and one for the contiguous U.S. The eight NCA regions are the Northeast, Southeast, Midwest, Great Plains, Northwest, Southwest, Alaska, and Hawaiâi/Pacific Islands.
These documents include a description of the observed historical climate conditions for each region and a set of climate scenarios as plausible futures â these components are described in more detail below.
While the datasets and simulations in these regional climate documents are not, by themselves, new, (they have been previously published in various sources), these documents represent a more complete and targeted synthesis of historical and plausible future climate conditions around the specific regions of the NCA.
There are two components of these descriptions. One component is a description of the historical climate conditions in the region. The other component is a description of the climate conditions associated with two future pathways of greenhouse gas emissions
Galaxy And Mass Assembly: Galaxy Zoo spiral arms and star formation rates
Understanding the effect spiral structure has on star formation properties of galaxies is important to complete our picture of spiral structure evolution. Previous studies have investigated connections between spiral arm properties and star formation, but the effect that the number of spiral arms has on this process is unclear. Here, we use the Galaxy And Mass Assembly (GAMA) survey paired with the citizen science visual classifications from the Galaxy Zoo project to explore galaxiesâ spiral arm number and how it connects to the star formation process. We use the votes from the GAMA-Kilo Degree Survey Galaxy Zoo classification to investigate the link between spiral arm number and stellar mass, star formation rate, and specific star formation rate (sSFR). We find that galaxies with fewer spiral arms have lower stellar masses and higher sSFRs, while those with more spiral arms tend towards higher stellar masses and lower sSFRs, and conclude that galaxies are less efficient at forming stars if they have more spiral arms. We note how previous studiesâ findings may indicate a cause for this connection in spiral arm strength or opacity
Quality Of Antenatal Care In Rural Southern Tanzania: A Reality Check.
Counselling on the danger signs of unpredictable obstetric complications and the appropriate management of such complications are crucial in reducing maternal mortality. The objectives of this study were to identify gaps in the provision of ANC services and knowledge of danger signs as well as the quality of care women receive in case of complications. The study took place in the Rufiji District of Tanzania in 2008 and was conducted in seven health facilities. The study used (1) observations from 63 antenatal care (ANC) sessions evaluated with an ANC checklist, (2) self-assessments of 11 Health workers, (3) interviews with 28 pregnant women and (4) follow-up of 12 women hospitalized for pregnancy-related conditions.Blood pressure measurements and abdominal examinations were common during ANC visits while urine testing for albumin or sugar or haemoglobin levels was rare which was often explained as due to a lack of supplies. The reasons for measuring blood pressure or abdominal examinations were usually not explained to the women. Only 15/28 (54%) women were able to mention at least one obstetric danger sign requiring medical attention. The outcomes of ten complicated cases were five stillbirths and three maternal complications. There was a considerable delay in first contact with a health professional or the start of timely interventions including checking vital signs, using a partograph, and detailed record keeping. Linking danger signs to clinical and laboratory examination results during ANC with the appropriate follow up and avoiding delays in emergency obstetric care are crucial to the delivery of coordinated, effective care interventions
CalFUSE v3: A Data-Reduction Pipeline for the Far Ultraviolet Spectroscopic Explorer
Since its launch in 1999, the Far Ultraviolet Spectroscopic Explorer (FUSE)
has made over 4600 observations of some 2500 individual targets. The data are
reduced by the Principal Investigator team at the Johns Hopkins University and
archived at the Multimission Archive at Space Telescope (MAST). The
data-reduction software package, called CalFUSE, has evolved considerably over
the lifetime of the mission. The entire FUSE data set has recently been
reprocessed with CalFUSE v3.2, the latest version of this software. This paper
describes CalFUSE v3.2, the instrument calibrations upon which it is based, and
the format of the resulting calibrated data files.Comment: To appear in PASP; 29 pages, 13 figures, uses aastex, emulateap
Magnetic phase diagram of cubic perovskites SrMn_1-xFe_xO_3
We combine the results of magnetic and transport measurements with Mossbauer
spectroscopy and room-temperature diffraction data to construct the magnetic
phase diagram of the new family of cubic perovskite manganites SrMn_1-xFe_xO_3.
We have found antiferromagnetic ordering for lightly and heavily Fe-substituted
material, while intermediate substitution leads to spin-glass behavior. Near
the SrMn_0.5Fe_0.5O_3 composition these two types of ordering are found to
coexist and affect one another. The spin glass behavior may be caused by
competing ferro- and antiferromagnetic interactions among Mn^4+ and observed
Fe^3+ and Fe^5+ ions.Comment: 8 pages, 10 figures, revtex, accepted to Phys. Rev.
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