1,319 research outputs found
Automated polysomnographic assessment for rapid eye movement sleep behavior disorder
Methods and systems for diagnosing or assessing rapid eye movement sleep behavior disorder (RBD). Muscle tone or activity variance during rapid eye movement (REM) and nonrapid eye movement (NREM) sleep intervals of a polysom- nogram are compared. A threshold based on the NREM data is used to identify a subj ect-specific threshold for abnormality in the REM variance. A metric that includes the percentage of REM variance exceeding the threshold relates to RBD.https://digitalcommons.mtu.edu/patents/1017/thumbnail.jp
Effects Of The Ionosphere On Ground-Based Detection Of The Global 21 CM Signal From The Cosmic Dawn And The Dark Ages
Detection of the global HI 21 cm signal from Cosmic Dawn and Epoch of
Reionization is the key science driver for several ongoing ground-based and
future ground/space-based experiments. The crucial spectral features in the
global 21 cm signal (turning points) occur at low radio frequencies <100 MHz.
In addition to the human-generated RFI, Earth's ionosphere drastically corrupts
low-frequency radio observations from the ground. In this paper, we examine the
effects of time-varying ionospheric refraction, absorption and thermal emission
at these low radio frequencies and their combined effect on any ground-based
global 21 cm experiment. It should be noted that this is the first study of the
effect of a dynamic ionosphere on global 21 cm experiments. The fluctuations in
the ionosphere are influenced by solar activity with flicker noise
characteristics. The same characteristics are reflected in the ionospheric
corruption to any radio signal passing through the ionosphere. As a result, any
ground based observations of the faint global 21 cm signal are corrupted by
flicker noise (or "" noise, where "" is the dynamical frequency) which
scales as (where is the frequency of observation) in the
presence of a bright galactic foreground (, where is
radio spectral index). Hence, the calibration of the ionosphere for any such
experiment is critical. Any attempt to calibrate the ionospheric effects will
be subject to the inaccuracies in the current ionospheric measurements using
GPS ionospheric measurements, riometer measurements, ionospheric soundings,
etc. Even considering an optimistic improvement in the accuracy of GPS-TEC
(Total Electron Content) measurements, we conclude that the detection of the
global 21 cm signal below 100 MHz is best done from above the Earth's
atmosphere in orbit of the Moon.Comment: 15 pages, 11 figures. Submitted to The Astrophysical Journal. This is
an updated version after addressing the comments from the refere
Physical characteristics and non-keplerian orbital motion of "propeller" moons embedded in Saturn's rings
We report the discovery of several large "propeller" moons in the outer part
of Saturn's A ring, objects large enough to be followed over the 5-year
duration of the Cassini mission. These are the first objects ever discovered
that can be tracked as individual moons, but do not orbit in empty space. We
infer sizes up to 1--2 km for the unseen moonlets at the center of the
propeller-shaped structures, though many structural and photometric properties
of propeller structures remain unclear. Finally, we demonstrate that some
propellers undergo sustained non-keplerian orbit motion. (Note: This arXiv
version of the paper contains supplementary tables that were left out of the
ApJL version due to lack of space).Comment: 9 pages, 4 figures; Published in ApJ
Dark Ages Radio Explorer Mission: Probing the Cosmic Dawn
The period between the creation of the cosmic microwave background at a
redshift of ~1000 and the formation of the first stars and black holes that
re-ionize the intergalactic medium at redshifts of 10-20 is currently
unobservable. The baryonic component of the universe during this period is
almost entirely neutral hydrogen, which falls into local regions of higher dark
matter density. This seeds the formation of large-scale structures including
the cosmic web that we see today in the filamentary distribution of galaxies
and clusters of galaxies. The only detectable signal from these dark ages is
the 21-cm spectral line of hydrogen, redshifted down to frequencies of
approximately 10-100 MHz. Space-based observations of this signal will allow us
to determine the formation epoch and physics of the first sources of ionizing
radiation, and potentially detect evidence for the decay of dark matter
particles. JPL is developing deployable low frequency antenna and receiver
prototypes to enable both all-sky spectral measurements of neutral hydrogen and
ultimately to map the spatial distribution of the signal as a function of
redshift. Such observations must be done from space because of Earth's
ionosphere and ubiquitous radio interference. A specific application of these
technologies is the Dark Ages Radio Explorer (DARE) mission. This small
Explorer class mission is designed to measure the sky-averaged hydrogen signal
from the shielded region above the far side of the Moon. These data will
complement ground-based radio observations of the final stages of intergalactic
re-ionization at higher frequencies. DARE will also serve as a scientific
percursor for space-based interferometry missions to image the distribution of
hydrogen during the cosmic dark ages.Comment: 2015 IEEE Aerospace Conferenc
Type and Timing of Rehabilitation Following Acute and Subacute Spinal Cord Injury: A Systematic Review
Objectives: The objective of this study was to conduct a systematic review of the literature to address the following clinical questions: In adult patients with acute and subacute complete or incomplete traumatic SCI, (1) does the time interval between injury and commencing rehabilitation affect outcome?; (2) what is the comparative effectiveness of different rehabilitation strategies, including different intensities and durations of treatment?; (3) are there patient or injury characteristics that affect the efficacy of rehabilitation?; and (4) what is the cost-effectiveness of various rehabilitation strategies? Methods: A systematic search was conducted for literature published through March 31, 2015 that evaluated rehabilitation strategies in adults with acute or subacute traumatic SCI at any level. Studies were critically appraised individually and the overall strength of evidence was evaluated using methods proposed by the GRADE (Grades of Recommendation Assessment, Development and Evaluation) working group. Results: The search strategy yielded 384 articles, 19 of which met our inclusion criteria. Based on our results, there was no difference between body weight–supported treadmill training and conventional rehabilitation with respect to improvements in Functional Independence Measure (FIM) Locomotor score, Lower Extremity Motor Scores, the distance walked in 6 minutes or gait velocity over 15.2 m. Functional electrical therapy resulted in slightly better FIM Motor, FIM Self-Care, and Spinal Cord Independence Measure Self-Care subscores compared with conventional occupational therapy. Comparisons using the Toronto Rehabilitation Institute Hand Function Test demonstrated no differences between groups in 7 of 9 domains. There were no clinically important differences in Maximal Lean Test, Maximal Sidewards Reach Test, T-shirt Test, or the Canadian Occupational Performance Measure between unsupported sitting training and standard in-patient rehabilitation. Conclusion: The current evidence base for rehabilitation following acute and subacute spinal cord injury is limited. Methodological challenges have contributed to this and further research is still needed. © 2017, © The Author(s) 2017
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