1,429 research outputs found
Data Streams from the Low Frequency Instrument On-Board the Planck Satellite: Statistical Analysis and Compression Efficiency
The expected data rate produced by the Low Frequency Instrument (LFI) planned
to fly on the ESA Planck mission in 2007, is over a factor 8 larger than the
bandwidth allowed by the spacecraft transmission system to download the LFI
data. We discuss the application of lossless compression to Planck/LFI data
streams in order to reduce the overall data flow. We perform both theoretical
analysis and experimental tests using realistically simulated data streams in
order to fix the statistical properties of the signal and the maximal
compression rate allowed by several lossless compression algorithms. We studied
the influence of signal composition and of acquisition parameters on the
compression rate Cr and develop a semiempirical formalism to account for it.
The best performing compressor tested up to now is the arithmetic compression
of order 1, designed for optimizing the compression of white noise like
signals, which allows an overall compression rate = 2.65 +/- 0.02. We find
that such result is not improved by other lossless compressors, being the
signal almost white noise dominated. Lossless compression algorithms alone will
not solve the bandwidth problem but needs to be combined with other techniques.Comment: May 3, 2000 release, 61 pages, 6 figures coded as eps, 9 tables (4
included as eps), LaTeX 2.09 + assms4.sty, style file included, submitted for
the pubblication on PASP May 3, 200
Hip-Hopping Over the Great Firewall of China: Authenticity, Language and Race in the Global Hip Hop Nation
This paper explores how Chinese youth interact and relate to this form of music and culture, and what this adaptation reveals about authenticity, class, race and regionalization in the age of digitized communication. For this paper, I ethnographically observe how participants experience Chinese Hip Hop as part of the Global spread of Hip Hop, as a cultural phenomenon that relates cosmopolitan marginalized youth identity, digital censorship, shedding light on relations to race, class, nationality and globalization among college aged international Chinese students studying at Bard College in Annandale-On-Hudson New York
CMB signal in WMAP 3yr data with FastICA
We present an application of the fast Independent Component Analysis
(FastICA) to the WMAP 3yr data with the goal of extracting the CMB signal. We
evaluate the confidence of our results by means of Monte Carlo simulations
including CMB, foreground contaminations and instrumental noise specific of
each WMAP frequency band. We perform a complete analysis involving all or a
subset of the WMAP channels in order to select the optimal combination for CMB
extraction, using the frequency scaling of the reconstructed component as a
figure of merit. We found that the combination KQVW provides the best CMB
frequency scaling, indicating that the low frequency foreground contamination
in Q, V and W bands is better traced by the emission in the K band. The CMB
angular power spectrum is recovered up to the degree scale, it is consistent
within errors for all WMAP channel combination considered, and in close
agreement with the WMAP 3yr results. We perform a statistical analysis of the
recovered CMB pattern, and confirm the sky asymmetry reported in several
previous works with independent techniques.Comment: 10 pages, 7 figures, submitted to MNRA
Processing of Irradiated 241Am Targets by Ion Exchange and Extraction. EUR 4409.
Abstract Background Evidence supporting the effectiveness of care management programs for complex patients has been inconclusive. However, past reviews have not focused on complexity primarily defined by multimorbidity and healthcare utilization. We conducted a systematic review of care management interventions targeting the following three patient groups: adults with two or more chronic medical conditions, adults with at least one chronic medical condition and concurrent depression, and adults identified based solely on high past or predicted healthcare utilization. Methods Eligible studies were identified from PubMed, published between 06/01/2005 and 05/31/2015, and reported findings from a randomized intervention that tested a comprehensive, care management intervention. Identified interventions were grouped based on the three “complex” categories of interest (described above). Two investigators extracted data using a structured abstraction form and assessed RCT quality. Results We screened 989 article titles for eligibility from which 847 were excluded. After reviewing the remaining 142 abstracts, 83 articles were excluded. We reviewed the full-text of 59 full-text articles and identified 15 unique RCTs for the final analysis. Of these 15 studies, two focused on patients with two or more chronic medical conditions, seven on patients with at least one chronic medical condition and depression, and six on patients with high past or predicted healthcare utilization. Measured outcomes included utilization, chronic disease measures, and patient-reported outcomes. The seven studies targeting patients with at least one chronic medical condition and depression demonstrated significant improvement in depression symptoms (ranging from 9.2 to 48.7% improvement). Of the six studies that focused on high utilizers, two showed small reductions in utilization. The quality of the research methodology in most of the studies (12/15) was rated fair or poor. Conclusions Interventions were more likely to be successful when patients were selected based on having at least one chronic medical condition and concurrent depression, and when patient-reported outcomes were assessed. Future research should focus on the role of mental health in complex care management, finding better methods for identifying patients who would benefit most from care management, and determining which intervention components are needed for which patients
Trade-off between angular resolution and straylight contamination in CMB anisotropy experiments. II. Straylight evaluation
Satellite CMB anisotropy missions and new generation of balloon-borne and
ground experiments, make use of complex multi-frequency instruments at the
focus of a meter class telescope. Between 70 GHz and 300 GHz, where foreground
contamination is minimum, it is extremely important to reach the best trade-off
between the improvement of the angular resolution and the minimization of the
straylight contamination mainly due to the Galactic emission. We focus here, as
a working case, on the 30 and 100 GHz channels of the Planck Low Frequency
Instrument (LFI). We evaluate the GSC introduced by the most relevant Galactic
foreground components for a reference set of optical configurations. We show
that it is possible to improve the angular resolution of 5-7% by keeping the
overall GSC below the level of few microKelvin. A comparison between the level
of straylight introduced by the different Galactic components for different
beam regions is presented. Simple approximate relations giving the rms and
peak-to-peak levels of the GSC are provided. We compare the results obtained at
100 GHz with those at 30 GHz, where GSC is more critical. Finally, we compare
the results based on Galactic foreground templates derived from radio and IR
surveys with those based on WMAP maps including CMB and extragalactic source
fluctuations.Comment: Submitted to A&A. Quality of the figures was degraded for
size-related reason
A unique aminoglycoside-O-phosphorylating activity mediating resistance to aminoglycosides in Escherichia coli
On the loss of telemetry data in full-sky surveys from space
In this paper we discuss the issue of loosing telemetry (TM) data due to
different reasons (e.g. spacecraft-ground transmissions) while performing a
full-sky survey with space-borne instrumentation. This is a particularly
important issue considering the current and future space missions (like Planck
from ESA and WMAP from NASA) operating from an orbit far from Earth with short
periods of visibility from ground stations. We consider, as a working case, the
Low Frequency Instrument (LFI) on-board the Planck satellite albeit the
approach developed here can be easily applied to any kind of experiment that
makes use of an observing (scanning) strategy which assumes repeated pointings
of the same region of the sky on different time scales. The issue is addressed
by means of a Monte Carlo approach. Our analysis clearly shows that, under
quite general conditions, it is better to cover the sky more times with a lower
fraction of TM retained than less times with a higher guaranteed TM fraction.
In the case of Planck, an extension of mission time to allow a third sky
coverage with 95% of the total TM guaranteed provides a significant reduction
of the probability to loose scientific information with respect to an increase
of the total guaranteed TM to 98% with the two nominal sky coverages.Comment: 17 pages, 6 figures, accepted for publication on New Astronom
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