51 research outputs found
Absolute diffuse calibration of IRAC through mid-infrared and radio study of HII regions
We investigate the diffuse absolute calibration of the InfraRed Array Camera
on the Spitzer Space Telescope at 8.0microns using a sample of 43 HII regions
with a wide range of morphologies near GLON=312deg. For each region we
carefully measure sky-subtracted,point-source- subtracted, areally-integrated
IRAC 8.0-micron fluxes and compare these with Midcourse Space eXperiment (MSX)
8.3-micron images at two different spatial resolutions, and with radio
continuum maps. We determine an accurate median ratio of IRAC
8.0-micron/MSX\8.3-micron fluxes, of 1.55+/-0.15. From robust spectral energy
distributions of these regions we conclude that the present 8.0-micron diffuse
calibration of the SST is 36% too high compared with the MSX validated
calibration, perhaps due to scattered light inside the camera. This is an
independent confirmation of the result derived for the diffuse calibration of
IRAC by the Spitzer Science Center (SSC).
From regression analyses we find that 843-MHz radio fluxes of HII regions and
mid-infrared (MIR) fluxes are linearly related for MSX at 8.3-microns and
Spitzer at 8.0 microns, confirming the earlier MSX result by Cohen & Green. The
median ratio of MIR/843-MHz diffuse continuum fluxes is 600 times smaller in
nonthermal than thermal regions, making it a sharp discriminant. The ratios are
largely independent of morphology up to a size of ~24 arcsec. We provide
homogeneous radio and MIR morphologies for all sources. MIR morphology is not
uniquely related to radio structure. Compact regions may have MIR filaments
and/or diffuse haloes, perhaps infrared counter- parts to weakly ionized radio
haloes found around compact HII regions. We offer two IRAC colour-colour plots
as quantitative diagnostics of diffuse HII regions.Comment: 29 pages, LaTeX (aastex), incl. 31 PostScript (ps,eps) figures and 5
tables. Accepted by MNRAS (main journal). Replaced an unused file and added
this URL for people wishing to download a version with high-resolution
images: http://www.astro.wisc.edu/sirtf/martin.hii.accepted.pd
G313.3+00.3: A New Planetary Nebula discovered by the Australia Telescope Compact Array and the Spitzer Space Telescope
We present a new planetary nebula, first identified in images from the
Australia Telescope Compact Array, although not recognized at that time. Recent
observations with the Spitzer Space Telescope during the GLIMPSE Legacy program
have rediscovered the object. The high-resolution radio and infrared images
enable the identification of the central star or its wind, the recognition of
the radio emission as thermal, and the probable presence of polycylic aromatic
hydrocarbons in and around the source. These lead to the conclusion that
G313.3+00.3 is a planetary nebula. This object is of particular interest
because it was discovered solely through radio and mid-infrared imaging,
without any optical (or near-infrared) confirmation, and acts as a proof of
concept for the discovery of many more highly extinguished planetary nebulae.
G313.3+00.3 is well-resolved by both the instruments with which it was
identified, and suffers extreme reddening due to its location in the
Scutum-Crux spiral arm.Comment: 18 pages, LaTeX (aastex), incl. 8 PostScript (eps) figures and 1
table. Accepted by ApJ (Part 1
Recommended from our members
The martian dust chronicle: Eight years of reconstructed climatology from spacecraft observations
We have reconstructed the climatology of airborne dust from Martian years (MY) 24 to 31 using multiple datasets
of retrieved or estimated column optical depth. The datasets are based on observations of the Martian atmosphere
from March 1999 to July 2013 by different orbiting instruments: the Thermal Emission Spectrometer (TES)
on board Mars Global Surveyor, the Thermal Emission Imaging System (THEMIS) on board Mars Odyssey,
and the Mars Climate Sounder (MCS) on board Mars Reconnaissance Orbiter (MRO). The procedure we have
adopted consists in gridding the available retrievals of column dust optical depth (CDOD) from TES and THEMIS
nadir observations, as well as the estimates of this quantity from MCS limb observations. Our gridding method
calculates weighted averages on a regular but likely incomplete spatial grid, using an iterative procedure with
weights in space, time, and retrieval uncertainty. The derived product consists of daily synoptic gridded maps of
CDOD at a resolution of 6 degree longitude x 3 degree latitude for MY 24-26, and 6 degree longitude x 5 degree
latitude for MY 27-31.
We have statistically analyzed the gridded maps to present an overview of the dust climatology on Mars
over eight years, specifically in relation to its intraseasonal and interannual variability.
Finally, we have produced complete daily maps of CDOD by spatially interpolating the available incomplete
gridded maps using a kriging method. These complete maps are used as dust scenarios in the Mars Climate
Database (MCD) version 5, and should be useful for many other applications.
The maps for the eight available Martian years are publicly available and distributed with open access, under
Creative Commons Attribution-ShareAlike 3.0 Unported License. The current version and future updates
can be downloaded from the MCD website at the Laboratoire de Meteorologie Dynamique: http://wwwmars.
lmd.jussieu.fr/mars/dust_climatology
Reconciling ice core CO2 and land use change following New World-Old World contact
Ice core records of carbon dioxide (CO2) throughout the last 2000 years provide context for the unprecedented anthropogenic rise in atmospheric CO2 and insights into global carbon cycle dynamics. Yet the atmospheric history of CO2 remains uncertain in some time intervals. Here we present measurements of CO2 and methane (CH4) in the Skytrain ice core from 1450 to 1700 CE. Results suggest a sudden decrease in CO2 around 1610 CE in one widely used record may be an artefact of a small number of anomalously low values. Our analysis supports a more gradual decrease in CO2 of 0.5 ppm per decade from 1516 to 1670 CE, with an inferred land carbon sink of 2.6 PgC per decade. This corroborates modelled scenarios of large-scale reorganisation of land use in the Americas following New World-Old World contact, whereas a rapid decrease in CO2 at 1610 CE is incompatible with even the most extreme land-use change scenarios
Evaluating the use of prostate-specific antigen as an instrument for early detection of prostate cancer beyond urologists: Results of a representative cross-sectional questionnaire study of general practitioners and internal specialists
OBJECTIVES The aim of this cross-sectional study was to evaluate the value of prostate-specific antigen (PSA) testing as a tool for early detection of prostate cancer (PCa) applied by general practitioners (GPs) and internal specialists (ISs) as well as to assess criteria leading to the application of PSA-based early PCa detection.
METHODS Between May and December 2012, a questionnaire containing 16 items was sent to 600 GPs and ISs in the federal state Brandenburg and in Berlin (Germany). The independent influence of several criteria on the decision of GPs and ISs to apply PSA-based early PCa detection was assessed by multivariate logistic regression analysis (MLRA).
RESULTS 392 evaluable questionnaires were collected (return rate 65%). 81% of the physicians declared that they apply PSA testing for early PCa detection; of these, 58 and 15% would screen patients until the age of 80 and 90 years, respectively. In case of a pathological PSA level, 77% would immediately refer the patient to a urologist, while 13% would re-assess elevated PSA levels after 3-12 months. Based on MLRA, the following criteria were independently associated with a positive attitude towards PSA-based early PCa detection: specialisation (application of early detection more frequent for GPs and hospital-based ISs) (OR 3.12; p < 0.001), physicians who use exclusively GP or IS education (OR 3.95; p = 0.002), and physicians who recommend yearly PSA assessment after the age of 50 (OR 6.85; p < 0.001).
CONCLUSIONS GPs and ISs frequently apply PSA-based early PCa detection. In doing so, 13% would initiate specific referral to a urologist in case of pathological PSA values too late. Improvement of this situation could possibly result from specific educational activities for non-urological physicians active in fields of urological core capabilities, which should be guided by joint boards of the national associations of urology and general medicine
Conduit artery structure and function in lowlanders and native highlanders: relationships with oxidative stress and role of sympathoexcitation
Research detailing the normal vascular adaptions to high altitude is minimal and
often confounded by pathology (e.g. chronic mountain sickness) and methodological issues.
We examined vascular function and structure in: (1) healthy lowlanders during acute hypoxia and prolonged ( 2 weeks) exposure to high altitude, and (2) high-altitude natives at 5050 m (highlanders). In 12 healthy lowlanders (aged 32 ± 7 years) and 12 highlanders(Sherpa; 33 ± 14 years) we assessed brachial endothelium-dependent flow-mediated dilatation(FMD), endothelium-independent dilatation (via glyceryl trinitrate; GTN), common carotid intimaâmedia thickness (CIMT) and diameter (ultrasound), and arterial stiffness via pulse wave velocity (PWV; applanation tonometry). Cephalic venous biomarkers of free radical-mediated lipid peroxidation (lipid hydroperoxides, LOOH), nitrite (NO2 â) and lipid soluble antioxidants were also obtained at rest. In lowlanders, measurements were performed at sea level (334 m) and between days 3â4 (acute high altitude) and 12â14 (chronic high altitude) following arrival to 5050 m. Highlanders were assessed once at 5050 m. Compared with sea level, acute high altitude reduced lowlandersâ FMD (7.9 ± 0.4 vs. 6.8 ± 0.4%; P = 0.004) and GTN-induced dilatation (16.6 ± 0.9 vs. 14.5 ± 0.8%; P = 0.006), and raised central PWV (6.0 ± 0.2 vs. 6.6 ± 0.3 m sâ1; P = 0.001). These changes persisted at days 12â14, and after allometricallyscaling FMD to adjust for altered baseline diameter. Compared to lowlanders at sea level and high altitude, highlanders had a lower carotid wall:lumen ratio ( 19%, P 0.04), attributable to a narrower CIMT and wider lumen. Although both LOOH and NO2 â increased with high altitude in lowlanders, only LOOH correlated with the reduction in GTN-induced dilatation
evident during acute (n = 11, r=â0.53) and chronic (n = 7, r=â0.69; P 0.01) exposure to 5050 m. In a follow-up, placebo-controlled experiment (n=11 healthy lowlanders) conducted in a normobaric hypoxic chamber (inspiredO2 fraction (FIO2 )=0.11; 6 h), a sustained reduction in FMD was evident within 1 h of hypoxic exposure when compared to normoxic baseline (5.7±1.6 vs. 8.0 ±1.3%; P < 0.01); this decline in FMD was largely reversed following α1-adrenoreceptor blockade. In conclusion, high-altitude exposure in lowlanders caused persistent impairment in vascular function, which was mediated partially via oxidative stress and sympathoexcitation. Although a lifetime of high-altitude exposure neither intensifies nor attenuates the impairments seen with short-term exposure, chronic high-altitude exposure appears to be associated with arterial remodelling
Mosaic: A Satellite Constellation to Enable Groundbreaking Mars Climate System Science and Prepare for Human Exploration
The Martian climate system has been revealed to rival the complexity of Earth\u27s. Over the last 20 yr, a fragmented and incomplete picture has emerged of its structure and variability; we remain largely ignorant of many of the physical processes driving matter and energy flow between and within Mars\u27 diverse climate domains. Mars Orbiters for Surface, Atmosphere, and Ionosphere Connections (MOSAIC) is a constellation of ten platforms focused on understanding these climate connections, with orbits and instruments tailored to observe the Martian climate system from three complementary perspectives. First, low-circular near-polar Sun-synchronous orbits (a large mothership and three smallsats spaced in local time) enable vertical profiling of wind, aerosols, water, and temperature, as well as mapping of surface and subsurface ice. Second, elliptical orbits sampling all of Mars\u27 plasma regions enable multipoint measurements necessary to understand mass/energy transport and ion-driven escape, also enabling, with the polar orbiters, dense radio occultation coverage. Last, longitudinally spaced areostationary orbits enable synoptic views of the lower atmosphere necessary to understand global and mesoscale dynamics, global views of the hydrogen and oxygen exospheres, and upstream measurements of space weather conditions. MOSAIC will characterize climate system variability diurnally and seasonally, on meso-, regional, and global scales, targeting the shallow subsurface all the way out to the solar wind, making many first-of-their-kind measurements. Importantly, these measurements will also prepare for human exploration and habitation of Mars by providing water resource prospecting, operational forecasting of dust and radiation hazards, and ionospheric communication/positioning disruptions
Controls over Ocean Mesopelagic Interior Carbon Storage (COMICS): Fieldwork, Synthesis, and Modeling Efforts
The ocean's biological carbon pump plays a central role in regulating atmospheric CO2 levels. In particular, the depth at which sinking organic carbon is broken down and respired in the mesopelagic zone is critical, with deeper remineralization resulting in greater carbon storage. Until recently, however, a balanced budget of the supply and consumption of organic carbon in the mesopelagic had not been constructed in any region of the ocean, and the processes controlling organic carbon turnover are still poorly understood. Large-scale data syntheses suggest that a wide range of factors can influence remineralization depth including upper-ocean ecological interactions, and interior dissolved oxygen concentration and temperature. However, these analyses do not provide a mechanistic understanding of remineralization, which increases the challenge of appropriately modeling the mesopelagic carbon dynamics. In light of this, the UK Natural Environment Research Council has funded a programme with this mechanistic understanding as its aim, drawing targeted fieldwork right through to implementation of a new parameterization for mesopelagic remineralization within an IPCC class global biogeochemical model. The Controls over Ocean Mesopelagic Interior Carbon Storage (COMICS) programme will deliver new insights into the processes of carbon cycling in the mesopelagic zone and how these influence ocean carbon storage. Here we outline the programme's rationale, its goals, planned fieldwork, and modeling activities, with the aim of stimulating international collaboration
WELLFOCUS PPT â modified positive psychotherapy to improve well-being in psychosis: study protocol for a pilot randomised controlled trial
BACKGROUND: The promotion of well-being is an important goal of recovery oriented mental health services. No structured, evidence-based intervention exists that aims to increase the well-being in people with severe mental illness such as psychosis. Positive psychotherapy (PPT) is a promising intervention for this goal. Standard PPT was adapted for use with people with psychosis in the UK following the Medical Research Council framework for developing and testing complex interventions, resulting in the WELLFOCUS Model describing the intended impact of WELLFOCUS PPT. This study aims to test the WELLFOCUS Model, by piloting the intervention, trial processes, and evaluation strategy. METHODS/DESIGN: This study is a non-blinded pragmatic pilot RCT comparing WELLFOCUS PPT provided as an 11-session group therapy in addition to treatment as usual to treatment as usual alone. Inclusion criteria are adults (aged 18â65 years) with a main diagnosis of psychosis who use mental health services. A target sample of 80 service users with psychosis are recruited from mental health services across the South London and Maudsley NHS Foundation Trust. Participants are randomised in blocks to the intervention and control group. WELLFOCUS PPT is provided to groups by specifically trained and supervised local therapists and members of the research team. Assessments are conducted before randomisation and after the group intervention. The primary outcome measure is well-being assessed by the Warwick-Edinburgh Mental Well-being Scale. Secondary outcomes include good feelings, symptom relief, connectedness, hope, self-worth, empowerment, and meaning. Process evaluation using data collected during the group intervention, post-intervention individual interviews and focus groups with participants, and interviews with trial therapists will complement quantitative outcome data. DISCUSSION: This study will provide data on the feasibility of the intervention and identify necessary adaptations. It will allow optimisation of trial processes and inform the evaluation strategy, including sample size calculation, for a future definitive RCT. TRIAL REGISTRATION: Current Controlled Trials ISRCTN04199273 â WELLFOCUS study: an intervention to improve well-being in people with psychosis, Date registered: 27 March 2013, first participant randomised on 26 April 2013
The James Webb Space Telescope Mission
Twenty-six years ago a small committee report, building on earlier studies,
expounded a compelling and poetic vision for the future of astronomy, calling
for an infrared-optimized space telescope with an aperture of at least .
With the support of their governments in the US, Europe, and Canada, 20,000
people realized that vision as the James Webb Space Telescope. A
generation of astronomers will celebrate their accomplishments for the life of
the mission, potentially as long as 20 years, and beyond. This report and the
scientific discoveries that follow are extended thank-you notes to the 20,000
team members. The telescope is working perfectly, with much better image
quality than expected. In this and accompanying papers, we give a brief
history, describe the observatory, outline its objectives and current observing
program, and discuss the inventions and people who made it possible. We cite
detailed reports on the design and the measured performance on orbit.Comment: Accepted by PASP for the special issue on The James Webb Space
Telescope Overview, 29 pages, 4 figure
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