350 research outputs found
A Low Noise Thermometer Readout for Ruthenium Oxide Resistors
The thermometer and thermal control system, for the Absolute Radiometer for
Cosmology, Astrophysics, and Diffuse Emission (ARCADE) experiment, is
described, including the design, testing, and results from the first flight of
ARCADE. The noise is equivalent to about 1 Omega or 0.15 mK in a second for the
RuO_2 resistive thermometers at 2.7 K. The average power dissipation in each
thermometer is 1 nW. The control system can take full advantage of the
thermometers to maintain stable temperatures. Systematic effects are still
under investigation, but the measured precision and accuracy are sufficient to
allow measurement of the cosmic background spectrum.
Journal-ref: Review of Scientific Instruments Vol 73 #10 (Oct 2002)Comment: 5 pages text 7 figure
ARCADE: Absolute Radiometer for Cosmology, Astrophysics, and Diffuse Emission
The Absolute Radiometer for Cosmology, Astrophysics, and Diffuse Emission
(ARCADE) is a balloon-borne instrument designed to measure the temperature of
the cosmic microwave background at centimeter wavelengths. ARCADE searches for
deviations from a blackbody spectrum resulting from energy releases in the
early universe. Long-wavelength distortions in the CMB spectrum are expected in
all viable cosmological models. Detecting these distortions or showing that
they do not exist is an important step for understanding the early universe. We
describe the ARCADE instrument design, current status, and future plans.Comment: 12 pages, 6 figures. Proceedings of the Fundamental Physics With CMB
workshop, UC Irvine, March 23-25, 2006, to be published in New Astronomy
Review
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Cancer Informatics for Cancer Centers (CI4CC): Building a Community Focused on Sharing Ideas and Best Practices to Improve Cancer Care and Patient Outcomes.
Cancer Informatics for Cancer Centers (CI4CC) is a grassroots, nonprofit 501c3 organization intended to provide a focused national forum for engagement of senior cancer informatics leaders, primarily aimed at academic cancer centers anywhere in the world but with a special emphasis on the 70 National Cancer Institute-funded cancer centers. Although each of the participating cancer centers is structured differently, and leaders' titles vary, we know firsthand there are similarities in both the issues we face and the solutions we achieve. As a consortium, we have initiated a dedicated listserv, an open-initiatives program, and targeted biannual face-to-face meetings. These meetings are a place to review our priorities and initiatives, providing a forum for discussion of the strategic and pragmatic issues we, as informatics leaders, individually face at our respective institutions and cancer centers. Here we provide a brief history of the CI4CC organization and meeting highlights from the latest CI4CC meeting that took place in Napa, California from October 14-16, 2019. The focus of this meeting was "intersections between informatics, data science, and population science." We conclude with a discussion on "hot topics" on the horizon for cancer informatics
ARCADE 2 Measurement of the Extra-Galactic Sky Temperature at 3-90 GHz
The ARCADE 2 instrument has measured the absolute temperature of the sky at
frequencies 3, 8, 10, 30, and 90 GHz, using an open-aperture cryogenic
instrument observing at balloon altitudes with no emissive windows between the
beam-forming optics and the sky. An external blackbody calibrator provides an
{\it in situ} reference. Systematic errors were greatly reduced by using
differential radiometers and cooling all critical components to physical
temperatures approximating the CMB temperature. A linear model is used to
compare the output of each radiometer to a set of thermometers on the
instrument. Small corrections are made for the residual emission from the
flight train, balloon, atmosphere, and foreground Galactic emission. The ARCADE
2 data alone show an extragalactic rise of mK at 3.3 GHz in addition
to a CMB temperature of K. Combining the ARCADE 2 data with
data from the literature shows a background power law spectrum of [K] from 22 MHz to 10 GHz ( GHz)
in addition to a CMB temperature of K.Comment: 11 pages 5 figures Submitted to Ap
The Temperature of the CMB at 10 GHz
We report the results of an effort to measure the low frequency portion of
the spectrum of the Cosmic Microwave Background Radiation (CMB), using a
balloon-borne instrument called ARCADE (Absolute Radiometer for Cosmology,
Astrophysics, and Diffuse Emission). These measurements are to search for
deviations from a thermal spectrum that are expected to exist in the CMB due to
various processes in the early universe. The radiometric temperature was
measured at 10 and 30 GHz using a cryogenic open-aperture instrument with no
emissive windows. An external blackbody calibrator provides an in situ
reference. A linear model is used to compare the radiometer output to a set of
thermometers on the instrument. The unmodeled residuals are less than 50 mK
peak-to-peak with a weighted RMS of 6 mK. Small corrections are made for the
residual emission from the flight train, atmosphere, and foreground Galactic
emission. The measured radiometric temperature of the CMB is 2.721 +/- 0.010 K
at 10 GHz and 2.694 +/- 0.032 K at 30 GHz.Comment: 8 pages including 5 figures. Submitted to The Astrophysical Journa
ARCADE 2 Observations of Galactic Radio Emission
We use absolutely calibrated data from the ARCADE 2 flight in July 2006 to
model Galactic emission at frequencies 3, 8, and 10 GHz. The spatial structure
in the data is consistent with a superposition of free-free and synchrotron
emission. Emission with spatial morphology traced by the Haslam 408 MHz survey
has spectral index beta_synch = -2.5 +/- 0.1, with free-free emission
contributing 0.10 +/- 0.01 of the total Galactic plane emission in the lowest
ARCADE 2 band at 3.15 GHz. We estimate the total Galactic emission toward the
polar caps using either a simple plane-parallel model with csc|b| dependence or
a model of high-latitude radio emission traced by the COBE/FIRAS map of CII
emission. Both methods are consistent with a single power-law over the
frequency range 22 MHz to 10 GHz, with total Galactic emission towards the
north polar cap T_Gal = 0.498 +/- 0.028 K and spectral index beta = -2.55 +/-
0.03 at reference frequency 1 GHz. The well calibrated ARCADE 2 maps provide a
new test for spinning dust emission, based on the integrated intensity of
emission from the Galactic plane instead of cross-correlations with the thermal
dust spatial morphology. The Galactic plane intensity measured by ARCADE 2 is
fainter than predicted by models without spinning dust, and is consistent with
spinning dust contributing 0.4 +/- 0.1 of the Galactic plane emission at 22
GHz.Comment: 10 poges, 9 figures. Submitted to The Astrophysical Journa
Learners in a Changing Learning Landscape: Reflections from an Instructional Design Perspective
Van Merriënboer, J. J. G., & Stoyanov, S. (2008). Learners in a changing learning landscape: Reflections from an instructional design perspective. In J. Visser & M. Visser-Valfrey (Eds.), Learners in a changing learning landscape: Reflections from a dialogue on new roles and expectations (pp. 69-90). Dordrecht, The Netherlands: Springer.Both learners and teachers find themselves in a learning landscape that is rapidly changing, along with fast societal and technological developments. This paper discusses the new learning landscape from an instructional design perspective. First, with regard to what is learned, people more than ever need flexible problem-solving and reasoning skills allowing them to deal with new, unfamiliar problem situations in their professional and everyday life. Second, with regard to the context in which learning takes place, learning in technology-rich, informal and professional 24/7 settings is becoming general practice. And third, with regard to the learners themselves, they can more often be characterized as lifelong learners who are mature, bring relevant prior knowledge, and have very heterogeneous expectations and perceptions of learning. High-quality instructional design research should focus on the question which instructional methods and media-method combinations are effective, efficient and appealing in this new learning landscape. Some innovative instructional methods that meet this requirement are discussed
Design and Calibration of a Cryogenic Blackbody Calibrator at Centimeter Wavelengths
We describe the design and calibration of an external cryogenic blackbody
calibrator used for the first two flights of the Absolute Radiometer for
Cosmology, Astrophysics, and Diffuse Emission (ARCADE) instrument. The
calibrator consists of a microwave absorber weakly coupled to a superfluid
liquid helium bath. Half-wave corrugations viewed 30 deg off axis reduce the
return loss below -35 dB. Ruthenium oxide resistive thermometers embedded
within the absorber monitor the temperature across the face of the calibrator.
The thermal calibration transfers the calibration of a reference thermometer to
the flight thermometers using the flight thermometer readout system. Data taken
near the superfluid transition in 8 independent calibrations 4 years apart
agree within 0.3 mK, providing an independent verification of the thermometer
calibration at temperatures near that of the cosmic microwave background.Comment: 5 pages including 5 figures. Submitted to Review of Scientific
Instrument
Detectable Clonal Mosaicism from Birth to Old Age and its Relationship to Cancer
Clonal mosaicism for large chromosomal anomalies (duplications, deletions and uniparental disomy) was detected using SNP microarray data from over 50,000 subjects recruited for genome-wide association studies. This detection method requires a relatively high frequency of cells (>5–10%) with the same abnormal karyotype (presumably of clonal origin) in the presence of normal cells. The frequency of detectable clonal mosaicism in peripheral blood is low (<0.5%) from birth until 50 years of age, after which it rises rapidly to 2–3% in the elderly. Many of the mosaic anomalies are characteristic of those found in hematological cancers and identify common deleted regions that pinpoint the locations of genes previously associated with hematological cancers. Although only 3% of subjects with detectable clonal mosaicism had any record of hematological cancer prior to DNA sampling, those without a prior diagnosis have an estimated 10-fold higher risk of a subsequent hematological cancer (95% confidence interval = 6–18)
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Genome-wide association study of Tourette Syndrome
Tourette Syndrome (TS) is a developmental disorder that has one of the highest familial recurrence rates among neuropsychiatric diseases with complex inheritance. However, the identification of definitive TS susceptibility genes remains elusive. Here, we report the first genome-wide association study (GWAS) of TS in 1285 cases and 4964 ancestry-matched controls of European ancestry, including two European-derived population isolates, Ashkenazi Jews from North America and Israel, and French Canadians from Quebec, Canada. In a primary meta-analysis of GWAS data from these European ancestry samples, no markers achieved a genome-wide threshold of significance (p<5 × 10−8); the top signal was found in rs7868992 on chromosome 9q32 within COL27A1 (p=1.85 × 10−6). A secondary analysis including an additional 211 cases and 285 controls from two closely-related Latin-American population isolates from the Central Valley of Costa Rica and Antioquia, Colombia also identified rs7868992 as the top signal (p=3.6 × 10−7 for the combined sample of 1496 cases and 5249 controls following imputation with 1000 Genomes data). This study lays the groundwork for the eventual identification of common TS susceptibility variants in larger cohorts and helps to provide a more complete understanding of the full genetic architecture of this disorder
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