156 research outputs found
Pulsed Laser System to Simulate Effects of Cosmic Rays in Semiconductor Devices
Spaceflight system electronic devices must survive a wide range of radiation environments with various particle types including energetic protons, electrons, gamma rays, x-rays, and heavy ions. High-energy charged particles such as heavy ions can pass straight through a semiconductor material and interact with a charge-sensitive region, generating a significant amount of charge (electron-hole pairs) along their tracks. These excess charges can damage the device, and the response can range from temporary perturbations to permanent changes in the state or performance. These phenomena are called single event effects (SEE). Before application in flight systems, electronic parts need to be qualified and tested for performance and radiation sensitivity. Typically, their susceptibility to SEE is tested by exposure to an ion beam from a particle accelerator. At such facilities, the device under test (DUT) is irradiated with large beams so there is no fine resolution to investigate particular regions of sensitivity on the parts. While it is the most reliable approach for radiation qualification, these evaluations are time consuming and costly. There is always a need for new cost-efficient strategies to complement accelerator testing: pulsed lasers provide such a solution. Pulsed laser light can be utilized to simulate heavy ion effects with the advantage of being able to localize the sensitive region of an integrated circuit. Generally, a focused laser beam of approximately picosecond pulse duration is used to generate carrier density in the semiconductor device. During irradiation, the laser pulse is absorbed by the electronic medium with a wavelength selected accordingly by the user, and the laser energy can ionize and simulate SEE as would occur in space. With a tightly focused near infrared (NIR) laser beam, the beam waist of about a micrometer can be achieved, and additional scanning techniques are able to yield submicron resolution. This feature allows mapping of all of the sensitive regions of the studied device with fine resolution, unlike heavy ion experiments. The problematic regions can be precisely identified, and it provides a considerable amount of information about the circuit. In addition, the system allows flexibility for testing the device in different configurations in situ
Symptom Burden in Long-Term Survivors of Head and Neck Cancer: Patient-Reported Versus Clinical Data
Introduction: The symptom burden faced by long-term head and neck cancer survivors is not well understood. In addition, the accuracy of clinical data sources for symptom ascertainment is not clear.
Objective: To 1) describe the prevalence of symptoms in 5-year survivors of head and neck cancer, and 2) to evaluate agreement between symptoms obtained via self-report and symptoms obtained from clinical data sources.
Methods: We recruited 5-year survivors of head and neck cancer enrolled at Kaiser Permanente Washington (n = 54). Symptoms were assessed using the MD Anderson Symptom Inventory head and neck cancer module. For each symptom, we assessed the agreement of the patient\u27s survey response ( gold standard ) with the 1) medical chart and 2) administrative health care claims data. We computed the sensitivity, specificity, positive predictive value (PPV), and negative predictive value, along with their 95 percent confidence intervals, for each clinical data source.
Results: Eighty percent of patients responded. Nearly all participants (95 percent) reported experiencing at least one symptom from the MDASI-HN, and 93 percent reported two or more symptoms. Among patients reporting a given symptom, there was generally no evidence of the symptom from either clinical data source (i.e., sensitivity was generally no greater than 40 percent). The specificity and PPV of the clinical data sources were generally higher than the sensitivity.
Conclusion: Relying only on medical chart review and/or administrative health data would substantially underestimate symptom burden in long-term head and neck cancer survivors
An Automated Method for the Detection and Extraction of HI Self-Absorption in High-Resolution 21cm Line Surveys
We describe algorithms that detect 21cm line HI self-absorption (HISA) in
large data sets and extract it for analysis. Our search method identifies HISA
as spatially and spectrally confined dark HI features that appear as negative
residuals after removing larger-scale emission components with a modified CLEAN
algorithm. Adjacent HISA volume-pixels (voxels) are grouped into features in
(l,b,v) space, and the HI brightness of voxels outside the 3-D feature
boundaries is smoothly interpolated to estimate the absorption amplitude and
the unabsorbed HI emission brightness. The reliability and completeness of our
HISA detection scheme have been tested extensively with model data. We detect
most features over a wide range of sizes, linewidths, amplitudes, and
background levels, with poor detection only where the absorption brightness
temperature amplitude is weak, the absorption scale approaches that of the
correlated noise, or the background level is too faint for HISA to be
distinguished reliably from emission gaps. False detection rates are very low
in all parts of the parameter space except at sizes and amplitudes approaching
those of noise fluctuations. Absorption measurement biases introduced by the
method are generally small and appear to arise from cases of incomplete HISA
detection. This paper is the third in a series examining HISA at high angular
resolution. A companion paper (Paper II) uses our HISA search and extraction
method to investigate the cold atomic gas distribution in the Canadian Galactic
Plane Survey.Comment: 39 pages, including 14 figure pages; to appear in June 10 ApJ, volume
626; figure quality significantly reduced for astro-ph; for full resolution,
please see http://www.ras.ucalgary.ca/~gibson/hisa/cgps1_survey
A survey for hydroxyl in the THOR pilot region around W43
We report on observations of the hydroxyl radical (OH) within The H{\sc I}, OH Recombination line survey (THOR) pilot region. The region is bounded approximately between Galactic coordinates l=29.2 to 31.5 ∘ and b=-1.0 to +1.0 ∘ and includes the high-mass star forming region W43. We identify 103 maser sites, including 72 with 1612\,MHz masers, 42 showing masers in either of the main line transitions at 1665 and 1667\,MHz and four showing 1720\,MHz masers. Most maser sites with either main-line or 1720\,MHz emission are associated with star formation, whereas most of the 1612\,MHz masers are associated with evolved stars. We find that nearly all of the main-line maser sites are co-spatial with an infrared source, detected by GLIMPSE. We also find diffuse OH emission, as well as OH in absorption towards selected unresolved or partially resolved sites. Extended OH absorption is found towards the well known star forming complex W43 Main
A Pan-Carina YSO Catalog: Intermediate-Mass Young Stellar Objects in the Carina Nebula Identified Via Mid-Infrared Excess Emission
We present a catalog of 1439 young stellar objects (YSOs) spanning the 1.42
deg^2 field surveyed by the Chandra Carina Complex Project (CCCP), which
includes the major ionizing clusters and the most active sites of ongoing star
formation within the Great Nebula in Carina. Candidate YSOs were identified via
infrared (IR) excess emission from dusty circumstellar disks and envelopes,
using data from the Spitzer Space Telescope Vela--Carina survey and the
Two-Micron All Sky Survey. We model the 1--24 /mu m IR spectral energy
distributions of the YSOs to constrain physical properties. Our Pan-Carina YSO
Catalog (PCYC) is dominated by intermediate-mass (2 Msun < m < 10 Msun) objects
with disks, including Herbig Ae/Be stars and their less evolved progenitors.
The PCYC provides a valuable complementary dataset to the CCCP X-ray source
catalogs, identifying 1029 YSOs in Carina with no X-ray detection. We also
catalog 410 YSOs with X-ray counterparts, including 62 candidate protostars.
Candidate protostars with X-ray detections tend to be more evolved than those
without. In most cases, X-ray emission apparently originating from
intermediate-mass, disk-dominated YSOs is consistent with the presence of
low-mass companions, but we also find that X-ray emission correlates with
cooler stellar photospheres and higher disk masses. We suggest that
intermediate-mass YSOs produce X-rays during their early pre-main sequence
evolution, perhaps driven by magnetic dynamo activity during the convective
atmosphere phase, but this emission dies off as the stars approach the main
sequence. Extrapolating over the stellar initial mass function scaled to the
PCYC population, we predict a total population of >2x10^4 YSOs and a
present-day star formation rate (SFR) of >0.008 Msun/yr. The global SFR in the
Carina Nebula, averaged over the past ~5 Myr, has been approximately constant.Comment: 23 pages, 11 figures, accepted for the ApJS Special Issue on the
Chandra Carina Complex Project (CCCP), scheduled for publication in May 2011.
All 16 CCCP Special Issue papers, including a version of this article with
high-quality figures and full electronic tables, are available at
http://cochise.astro.psu.edu/Carina_public/special_issue.html (through 2011
at least
Compact HI clouds from the GALFA-HI survey
The Galactic Arecibo L-band Feed Array HI (GALFA-HI) survey is mapping the
entire Arecibo sky at 21-cm, over a velocity range of -700 to +700 km/s (LSR),
at a velocity resolution of 0.18 km/s and a spatial resolution of 3.5 arcmin.
The unprecedented resolution and sensitivity of the GALFA-HI survey have
resulted in the detection of numerous isolated, very compact HI clouds at low
Galactic velocities, which are distinctly separated from the HI disk emission.
In the limited area of ~4600 deg surveyed so far, we have detected 96 of
such compact clouds. The detected clouds are cold with a median T
(the kinetic temperature in the case in which there is no non-thermal
broadening) of 300 K. Moreover, these clouds are quite compact and faint, with
median values of 5 arcmin in angular size, 0.75 K in peak brightness
temperature, and cm in HI column density. Most of the
clouds deviate from Galactic rotation at the 20-30 km/s level, and a
significant fraction show evidence for a multiphase medium and velocity
gradients. No counterparts for these clouds were found in other wavebands. From
the modeling of spatial and velocity distributions of the whole compact cloud
population, we find that the bulk of the compact clouds are related to the
Galactic disk, and their distances are likely to be in the range of 0.1 to a
few kpc. We discuss various possible scenarios for the formation and
maintenance of this cloud population and its significance for Galactic ISM
studies.Comment: Accepted for publication in the Astrophysical Journa
Real-Time Ventilation Measurements from Mechanically Ventilated Livestock Buildings for Emission Rate Estimations
A six-state USDA-IFAFS funded research project (Aerial Pollutant Emissions from Confined Animal Buildings, APECAB) was conducted with the purpose of determining hydrogen sulfide, ammonia, PM10, and odor emission rates from selected swine and poultry housing systems. An important aspect of emission studies is to be able to measure the mass flow rate of air through the housing system. For this research project, the decision was made to study only fan ventilated buildings due to the difficulty in estimating mass flow rates through naturally ventilated buildings. This paper highlights the various techniques used throughout the study to determine mass flow rate through fan ventilated swine and poultry housing systems
A Look at the History of Biosimilar Adoption: Characteristics of Early and Late Adopters of Infliximab and Etanercept Biosimilars in Subregions of England, Scotland and Wales - A Mixed Methods Study
Background: Regions within England, Scotland and Wales show variation in rate of adoption of biosimilar infliximab and etanercept. Objectives: This study aims to examine how local decisions and practices in regions within England, Scotland and Wales might explain initial variation in market dynamics of biosimilar and originator infliximab and etanercept. Methods: Market data provided by the National Health Service (NHS) on biosimilar and originator infliximab and etanercept uptake were analysed for the 10 historical regions of England, 14 health boards in Scotland and 7 health boards in Wales (2015–2018). Findings were discussed in ten semi-structured interviews: on a national level with an industry representative (1), on a regional level with NHS employees in England (6), Scotland (1) and Wales (1), and on a local level with a representative of a clinical commissioning group in England (1). Results: Tenders for infliximab and etanercept in England, Scotland and Wales have consistently resulted in a biosimilar as the best value biological. Early and late biosimilar adopters are seen, with overall convergence towards high biosimilar market shares over time. Qualitative results suggest that biosimilar adoption was positively influenced by (a) a price difference between biosimilar and originator product making it worthwhile to switch patients; (b) a good relationship between commissioner and provider in England resulting in gain share agreements; (c) leadership on biosimilars in regional NHS offices in England or Scottish and Welsh health boards; (d) key opinion leaders or leading hospitals that start using biosimilars early and gain experience. Conclusions: This study has shown that the savings potential drives biosimilar use. Regions with a proactive attitude, good stakeholder relationships, and clinician engagement were identified as early adopters
Integrated Ecosystem Assessments: Developing the Scientific Basis for Ecosystem-Based Management of the Ocean
Integrated ecosystem assessments challenge the broader scientific community to move beyond the important task of tallying insults to marine ecosystems to developing quantitative tools that can support the decisions national and regional resource managers must make
GASKAP -- The Galactic ASKAP Survey
A survey of the Milky Way disk and the Magellanic System at the wavelengths
of the 21-cm atomic hydrogen (HI) line and three 18-cm lines of the OH molecule
will be carried out with the Australian Square Kilometre Array Pathfinder
telescope. The survey will study the distribution of HI emission and absorption
with unprecedented angular and velocity resolution, as well as molecular line
thermal emission, absorption, and maser lines. The area to be covered includes
the Galactic plane (|b|< 10deg) at all declinations south of delta = +40deg,
spanning longitudes 167deg through 360deg to 79deg at b=0deg, plus the entire
area of the Magellanic Stream and Clouds, a total of 13,020 square degrees. The
brightness temperature sensitivity will be very good, typically sigma_T ~ 1 K
at resolution 30arcsec and 1 km/s. The survey has a wide spectrum of scientific
goals, from studies of galaxy evolution to star formation, with particular
contributions to understanding stellar wind kinematics, the thermal phases of
the interstellar medium, the interaction between gas in the disk and halo, and
the dynamical and thermal states of gas at various positions along the
Magellanic Stream.Comment: 45 pages, 8 figures, Pub. Astron. Soc. Australia (in press
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