77 research outputs found
MRI safety and devices: An update and expert consensus
Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/154533/1/jmri26909_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/154533/2/jmri26909.pd
Red, Blue, and the Flu: Media Self-Selection and Partisan Gaps in Swine Flu Vaccinations
Upper limits on the strength of periodic gravitational waves from PSR J1939+2134
The first science run of the LIGO and GEO gravitational wave detectors
presented the opportunity to test methods of searching for gravitational waves
from known pulsars. Here we present new direct upper limits on the strength of
waves from the pulsar PSR J1939+2134 using two independent analysis methods,
one in the frequency domain using frequentist statistics and one in the time
domain using Bayesian inference. Both methods show that the strain amplitude at
Earth from this pulsar is less than a few times .Comment: 7 pages, 1 figure, to appear in the Proceedings of the 5th Edoardo
Amaldi Conference on Gravitational Waves, Tirrenia, Pisa, Italy, 6-11 July
200
Improving the sensitivity to gravitational-wave sources by modifying the input-output optics of advanced interferometers
We study frequency dependent (FD) input-output schemes for signal-recycling
interferometers, the baseline design of Advanced LIGO and the current
configuration of GEO 600. Complementary to a recent proposal by Harms et al. to
use FD input squeezing and ordinary homodyne detection, we explore a scheme
which uses ordinary squeezed vacuum, but FD readout. Both schemes, which are
sub-optimal among all possible input-output schemes, provide a global noise
suppression by the power squeeze factor, while being realizable by using
detuned Fabry-Perot cavities as input/output filters. At high frequencies, the
two schemes are shown to be equivalent, while at low frequencies our scheme
gives better performance than that of Harms et al., and is nearly fully
optimal. We then study the sensitivity improvement achievable by these schemes
in Advanced LIGO era (with 30-m filter cavities and current estimates of
filter-mirror losses and thermal noise), for neutron star binary inspirals, and
for narrowband GW sources such as low-mass X-ray binaries and known radio
pulsars. Optical losses are shown to be a major obstacle for the actual
implementation of these techniques in Advanced LIGO. On time scales of
third-generation interferometers, like EURO/LIGO-III (~2012), with
kilometer-scale filter cavities, a signal-recycling interferometer with the FD
readout scheme explored in this paper can have performances comparable to
existing proposals. [abridged]Comment: Figs. 9 and 12 corrected; Appendix added for narrowband data analysi
Search for gravitational wave bursts in LIGO's third science run
We report on a search for gravitational wave bursts in data from the three
LIGO interferometric detectors during their third science run. The search
targets subsecond bursts in the frequency range 100-1100 Hz for which no
waveform model is assumed, and has a sensitivity in terms of the
root-sum-square (rss) strain amplitude of hrss ~ 10^{-20} / sqrt(Hz). No
gravitational wave signals were detected in the 8 days of analyzed data.Comment: 12 pages, 6 figures. Amaldi-6 conference proceedings to be published
in Classical and Quantum Gravit
Money, (Co)Production and Power in Digital
This article discusses the contribution of critical political economy approaches to digital journalism studies and argues that these offer important correctives to celebratory perspectives. The first part offers a review and critique of influential claims arising from self-styled new studies of convergence culture, media and creative industries. The second part discusses the contribution of critical political economy in examining digital journalism and responding to celebrant claims. The final part reflects on problems of restrictive normativity and other limitations within media political economy perspectives and considers ways in which challenges might be addressed by more synthesising approaches. The paper proposes developing radical pluralist, media systems and comparative analysis, and advocates drawing on strengths in both political economy and culturalist traditions to map and evaluate practices across all sectors of digital journalism
Personalization and the Future of News
Over the past two decades, much scholarship has theorized about how highly personalized news media might change the public sphere. But even as algorithmic content filtering has become widespread, social science research has lagged in understanding how such systems work, and how they have altered competitive dynamics between media outlets. Drawing on recent research into recommender systems, this paper examines the Netflix prize, as well as collaborative filtering algorithms deployed by Google and Yahoo. Content recommendation systems strongly advantage the very largest websites over small news outlets, with profound implications for the online news landscape
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