102 research outputs found
Combined Multipoint Remote and In Situ Observations of the Asymmetric Evolution of a Fast Solar Coronal Mass Ejection
We present an analysis of the fast coronal mass ejection (CME) of 2012 March
7, which was imaged by both STEREO spacecraft and observed in situ by
MESSENGER, Venus Express, Wind and Mars Express. Based on detected arrivals at
four different positions in interplanetary space, it was possible to strongly
constrain the kinematics and the shape of the ejection. Using the white-light
heliospheric imagery from STEREO-A and B, we derived two different kinematical
profiles for the CME by applying the novel constrained self-similar expansion
method. In addition, we used a drag-based model to investigate the influence of
the ambient solar wind on the CME's propagation. We found that two preceding
CMEs heading in different directions disturbed the overall shape of the CME and
influenced its propagation behavior. While the Venus-directed segment underwent
a gradual deceleration (from ~2700 km/s at 15 R_sun to ~1500 km/s at 154
R_sun), the Earth-directed part showed an abrupt retardation below 35 R_sun
(from ~1700 to ~900 km/s). After that, it was propagating with a quasi-constant
speed in the wake of a preceding event. Our results highlight the importance of
studies concerning the unequal evolution of CMEs. Forecasting can only be
improved if conditions in the solar wind are properly taken into account and if
attention is also paid to large events preceding the one being studied
On the Propagation of a Geoeffective Coronal Mass Ejection during March 15 -- 17, 2015
The largest geomagnetic storm so far in the solar cycle 24 was produced by a
fast coronal mass ejection (CME) originating on 2015 March 15. It was an
initially west-oriented CME and expected to only cause a weak geomagnetic
disturbance. Why did this CME finally cause such a large geomagnetic storm? We
try to find some clues by investigating its propagation from the Sun to 1 AU.
First, we reconstruct the CME's kinematic properties in the corona from the
SOHO and SDO imaging data with the aid of the graduated cylindrical shell (GCS)
model. It is suggested that the CME propagated to the west
away from the Sun-Earth line with a speed of
about 817 km s before leaving the field of view of the SOHO/LASCO C3
camera. A magnetic cloud (MC) corresponding to this CME was measured in-situ by
the Wind spacecraft two days later. By applying two MC reconstruction methods,
we infer the configuration of the MC as well as some kinematic information,
which implies that the CME possibly experienced an eastward deflection on its
way to 1 AU. However, due to the lack of observations from the STEREO
spacecraft, the CME's kinematic evolution in interplanetary space is not clear.
In order to fill this gap, we utilize numerical MHD simulation, drag-based CME
propagation model (DBM) and the model for CME deflection in interplanetary
space (DIPS) to recover the propagation process, especially the trajectory, of
the CME from to 1 AU. It is suggested that the trajectory of the CME
was deflected toward the Earth by about , consistent with the
implication from the MC reconstruction at 1 AU. This eastward deflection
probably contributed to the CME's unexpected geoeffectiveness by pushing the
center of the initially west-oriented CME closer to the Earth.Comment: 10 pages, 5 figures, 1 table, accepted by JGR - Space Physic
SPARKESX: Single-dish PARKES data sets for finding the uneXpected -- A data challenge
New classes of astronomical objects are often discovered serendipitously. The
enormous data volumes produced by recent high-time resolution, radio-telescope
surveys imply that efficient algorithms are required for a discovery. Such
algorithms are usually tuned to detect specific, known sources. Existing data
sets therefore likely contain unknown astronomical sources, which will remain
undetected unless algorithms are developed that can detect a more diverse range
of signals. We present the Single-dish PARKES data challenge for finding the
uneXpected (SPARKESX), a compilation of real and simulated high-time resolution
observations. SPARKESX comprises three mock surveys from the Parkes "Murriyang"
radio telescope. A broad selection of simulated and injected expected signals
(such as pulsars, fast radio bursts), poorly characterised signals (plausible
flare star signatures) and unknown unknowns are generated for each survey. The
goal of this challenge is to aid in the development of new algorithms that can
detect a wide-range of source types. We show how successful a typical pipeline
based on the standard pulsar search software, PRESTO, is at finding the
injected signals. The dataset is publicly available at
https://doi.org/10.25919/fd4f-0g20.Comment: Accepted for publication in MNRAS. 18 pages, 8 figures, 4 tabl
Spin-echo and quantum versus classical critical fluctuations in TmVO
Using spin-echo Nuclear Magnetic Resonance in the model Transverse-Field
Ising system TmVO, we show that low frequency quantum fluctuations at the
quantum critical point have a very different effect on V nuclear-spins
than classical low-frequency noise or fluctuations that arise at a finite
temperature critical point. Spin-echos filter out the low frequency classical
noise but not the quantum fluctuations. This allows us to directly visualize
the quantum critical fan and demonstrate the persistence of quantum
fluctuations at the critical coupling strength in TmVO to high temperatures
in an experiment that remains transparent to finite temperature classical phase
transitions. These results show that while dynamical decoupling schemes can be
quite effective in eliminating classical noise in a qubit, a quantum critical
environment may lead to rapid entanglement and decoherence.Comment: 10 pages, 5 figure
The gravitational-wave background null hypothesis: Characterizing noise in millisecond pulsar arrival times with the Parkes Pulsar Timing Array
The noise in millisecond pulsar (MSP) timing data can include contributions
from observing instruments, the interstellar medium, the solar wind, solar
system ephemeris errors, and the pulsars themselves. The noise environment must
be accurately characterized in order to form the null hypothesis from which
signal models can be compared, including the signature induced by
nanohertz-frequency gravitational waves (GWs). Here we describe the noise
models developed for each of the MSPs in the Parkes Pulsar Timing Array (PPTA)
third data release, which have been used as the basis of a search for the
isotropic stochastic GW background. We model pulsar spin noise, dispersion
measure variations, scattering variations, events in the pulsar magnetospheres,
solar wind variability, and instrumental effects. We also search for new timing
model parameters and detected Shapiro delays in PSR~J06143329 and
PSR~J19025105. The noise and timing models are validated by testing the
normalized and whitened timing residuals for Gaussianity and residual
correlations with time. We demonstrate that the choice of noise models
significantly affects the inferred properties of a common-spectrum process.
Using our detailed models, the recovered common-spectrum noise in the PPTA is
consistent with a power law with a spectral index of , the value
predicted for a stochastic GW background from a population of supermassive
black hole binaries driven solely by GW emission.Comment: 18 pages, 10 figures. Accepted for publication in ApJ
European dermatology forum - updated guidelines on the use of extracorporeal photopheresis 2020 - part 1.
Following the first investigational study on the use of extracorporeal photopheresis for the treatment of cutaneous T-cell lymphoma published in 1983, this technology has received continued use and further recognition for additional earlier as well as refractory forms. After the publication of the first guidelines for this technology in the JEADV in 2014, this technology has maintained additional promise in the treatment of other severe and refractory conditions in a multi-disciplinary setting. It has confirmed recognition in well-known documented conditions such as graft-versus-host disease after allogeneic bone marrow transplantation, systemic sclerosis, solid organ transplant rejection including lung, heart and liver and to a lesser extent inflammatory bowel disease.
In order to further provide recognized expert practical guidelines for the use of this technology for all indications, the European Dermatology Forum (EDF) again proceeded to address these questions in the hands of the recognized experts within and outside the field of dermatology. This was done using the recognized and approved guidelines of EDF for this task. All authors had the opportunity to review each contribution as it was added.
These updated 2020 guidelines provide at present the most comprehensive available expert recommendations for the use of extracorporeal photopheresis based on the available published literature and expert consensus opinion. The guidelines are divided in two parts: PART I covers cutaneous T-cell lymphoma, chronic graft-versus-host disease and acute graft-versus-host disease while PART II will cover scleroderma, solid organ transplantation, Crohn's disease, use of ECP in paediatrics practice, atopic dermatitis, type 1 diabetes, pemphigus, epidermolysis bullosa acquisita and erosive oral lichen planus
ESPRAS Survey on Continuing Education in Plastic, Reconstructive and Aesthetic Surgery in Europe
Background Specialty training in plastic, reconstructive and aesthetic surgery is a prerequisite for safe and effective provision of care. The aim of this study was to assess and portray similarities and differences in the continuing education and specialization in plastic surgery in Europe. Material and Methods A detailed questionnaire was designed and distributed utilizing an online survey administration software. Questions addressed core items regarding continuing education and specialization in plastic surgery in Europe. Participants were addressed directly via the European Leadership Forum (ELF) of the European Society of Plastic, Reconstructive and Aesthetic Surgery (ESPRAS). All participants had detailed knowledge of the organization and management of plastic surgical training in their respective country. Results The survey was completed by 29 participants from 23 European countries. During specialization, plastic surgeons in Europe are trained in advanced tissue transfer and repair and aesthetic principles in all parts of the human body and within several subspecialties. Moreover, rotations in intensive as well as emergency care are compulsory in most European countries. Board certification is only provided for surgeons who have had multiple years of training regulated by a national board, who provide evidence of individually performed operative procedures in several anatomical regions and subspecialties, and who pass a final oral and/or written examination. Conclusion Board certified plastic surgeons meet the highest degree of qualification, are trained in all parts of the body and in the management of complications. The standard of continuing education and qualification of European plastic surgeons is high, providing an excellent level of plastic surgical care throughout Europe
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