4,966 research outputs found
The Coronal Analysis of SHocks and Waves (CASHeW) Framework
Coronal Bright Fronts (CBF) are large-scale wavelike disturbances in the
solar corona, related to solar eruptions. They are observed in extreme
ultraviolet (EUV) light as transient bright fronts of finite width, propagating
away from the eruption source. Recent studies of individual solar eruptive
events have used EUV observations of CBFs and metric radio type II burst
observations to show the intimate connection between low coronal waves and
coronal mass ejection (CME)-driven shocks. EUV imaging with the Atmospheric
Imaging Assembly(AIA) instrument on the Solar Dynamics Observatory (SDO) has
proven particularly useful for detecting CBFs, which, combined with radio and
in situ observations, holds great promise for early CME-driven shock
characterization capability. This characterization can further be automated,
and related to models of particle acceleration to produce estimates of particle
fluxes in the corona and in the near Earth environment early in events. We
present a framework for the Coronal Analysis of SHocks and Waves (CASHeW). It
combines analysis of NASA Heliophysics System Observatory data products and
relevant data-driven models, into an automated system for the characterization
of off-limb coronal waves and shocks and the evaluation of their capability to
accelerate solar energetic particles (SEPs). The system utilizes EUV
observations and models written in the Interactive Data Language (IDL). In
addition, it leverages analysis tools from the SolarSoft package of libraries,
as well as third party libraries. We have tested the CASHeW framework on a
representative list of coronal bright front events. Here we present its
features, as well as initial results. With this framework, we hope to
contribute to the overall understanding of coronal shock waves, their
importance for energetic particle acceleration, as well as to the better
ability to forecast SEP events fluxes.Comment: Accepted for publication in the Journal of Space Weather and Space
Climate (SWSC
Fluorescent probes of the orientation of myosin regulatory light chains in relaxed, rigor, and contracting muscle.
The orientation of the light-chain region of myosin heads in relaxed, rigor, and isometrically contracting fibers from rabbit psoas muscle was studied by fluorescence polarization. Cysteine 108 of chicken gizzard myosin regulatory light chain (cgRLC) was covalently modified with iodoacetamidotetramethylrhodamine (iodo-ATR). Native RLC of single glycerinated muscle fibers was exchanged for labeled cgRLC in a low [Mg2+] rigor solution at 30 degrees C. Troponin and troponin C removed in this procedure were replaced. RLC exchange had little effect on active force production. X-ray diffraction showed normal structure in rigor after RLC exchange, but loss of axial and helical order in relaxation. In isolated myofibrils labeled cgRLC was confined to the regions of the sarcomere containing myosin heads. The ATR dipoles showed a preference for orientations perpendicular to the fiber axis, combined with limited nanosecond rotational motion, in all conditions studied. The perpendicular orientation preference was more marked in rigor than in either relaxation or active contraction. Stretching relaxed fibers to sarcomere length 4 microns to eliminate overlap between actin- and myosin-containing filaments had little effect on the orientation preference. There was no change in orientation preference when fibers were put into rigor at sarcomere length 4.0 microns. Qualitatively similar results were obtained with ATR-labeled rabbit skeletal RLC
Blind estimation of reverberation time in classrooms and hospital wards
This paper investigates blind Reverberation Time (RT) estimation in occupied classrooms and hospital wards. Measurements are usually made while these spaces are unoccupied for logistical reasons. However, occupancy can have a significant impact on the rate of reverberant decay.
Recent work has developed a Maximum Likelihood Estimation (MLE) method which utilises only passively recorded speech and music signals, this enables measurements to be made while the room is in use. In this paper the MLE method is applied to recordings made in classrooms during lessons.
Classroom occupancy levels differ for each lesson, therefore a model is developed using blind estimates to predict the RT for any occupancy level to within ±0.07s for the mid-frequency octave bands. The model is also able to predict the effective room and per person absorption area.
Ambient sound recordings were also carried out in a number of rooms in two hospitals for a week.
Hospital measurements are more challenging as the occurrence of free reverberant decay is rarer than in schools and the acoustic conditions may be non-stationary. However, by gaining recordings over a period of a week, estimates can be gained within ±0.07 s. These estimates are representative of the times when the room contains the highest acoustic absorption. In other words when curtains
are drawn, there are many visitors or perhaps a window may be open
Constraining local non-Gaussianities with kSZ tomography
Kinetic Sunyaev Zel'dovich (kSZ) tomography provides a powerful probe of the
radial velocity field of matter in the Universe. By cross-correlating a high
resolution CMB experiment like CMB S4 and a galaxy survey like DESI or LSST,
one can measure the radial velocity field with very high signal to noise over a
large volume of the universe. In this paper we show how this measurement can be
used to improve constraints on primordial non-Gaussianities of the local type.
The velocity field provides a measurement of the unbiased matter perturbations
on large scales, which can be cross-correlated with the biased large-scale
galaxy density field. This results in sample variance cancellation for a
measurement of scale-dependent bias due to a non-zero . Using this
method we forecast that CMB S4 and LSST combined reach a sensitivity
, which is a factor of three improvement over the
sensitivity using LSST alone (without internal sample variance cancellation).
We take into account critical systematics like photometric redshifts, the kSZ
optical depth degeneracy, and systematics affecting the shape of the galaxy
auto-power spectrum and find that these have negligible impact, thus making kSZ
tomography a robust probe for primordial non-Gaussianities. We also forecast
the impact of mass binning on our constraints. The techniques proposed in this
paper could be an important component of achieving the theoretically important
threshold of with future surveys.Comment: 16 pages, 7 figure
Hypnosis for acute procedural pain: a critical review
Clinical evidence for the effectiveness of hypnosis in the treatment of acute procedural pain was critically evaluated based on reports from randomized controlled clinical trials (RCTs). Results from the 29 RCTs meeting inclusion criteria suggest that hypnosis decreases pain compared to standard care and attention control groups and that it is at least as effective as comparable adjunct psychological or behavioral therapies. In addition, applying hypnosis in multiple sessions prior to the day of the procedure produced the highest percentage of significant results. Hypnosis was most effective in minor surgical procedures. However, interpretations are limited by considerable risk of bias. Further studies using minimally effective control conditions and systematic control of intervention dose and timing are required to strengthen conclusions
Depletion of atmospheric nitrate and chloride as a consequence of the Toba Volcanic Eruption
Continuous measurements of SO42− and electrical conductivity (ECM) along the GISP2 ice core record the Toba mega‐eruption at a depth 2590.95 to 2091.25 m (71,000±5000 years ago). Major chemical species were analyzed at a resolution of 1 cm per sample for this section. An ∼6‐year long period with extremely high volcanic SO42− coincident with a 94% depletion of nitrate and 63% depletion of chloride is observed at the depth of the Toba horizon. Such a reduction of chloride in a volcanic layer preserved in an ice core has not been observed in any previous studies. The nearly complete depletion of nitrate (to 5 ppb) encountered at the Toba level is the lowest value in the entire ∼250,000 years of the GISP2 ice core record. We propose possible mechanisms to explain the depletion of nitrate and chloride resulting from this mega‐eruption
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