756 research outputs found
Eruptions from solar ephemeral regions as an extension of the size distribution of coronal mass ejections
Observations of the quiet solar corona in the 171A (~1MK) passband of the
Transition Region and Coronal Explorer (TRACE) often show disruptions of the
coronal part of small-scale ephemeral bipolar regions that resemble the
phenomena associated with coronal mass ejections on much larger scales:
ephemeral regions exhibit flare-like brightenings, rapidly rising filaments
carrying absorbing material at chromospheric temperatures, or the temporary
dimming of the surrounding corona. I analyze all available TRACE observing
sequences between 1998/04/01 and 2009/09/30 with full-resolution 171A image
sequences spanning a day or more within 500 arcsec of disk center, observing
essentially quiet Sun with good exposures and relatively low background. Ten
such data sets are identified between 2000 and 2008, spanning 570h of observing
with a total of 17133 exposures. Eighty small-scale coronal eruptions are
identified. Their size distribution forms a smooth extension of the
distribution of angular widths of coronal mass ejections, suggesting that the
eruption frequency for bipolar magnetic regions is essentially scale free over
at least two orders of magnitude, from eruptions near the arcsecond resolution
limit of TRACE to the largest coronal mass ejections observed in the inner
heliosphere. This scale range may be associated with the properties of the
nested set of ranges of connectivity in the magnetic field, in which
increasingly large and energetic events can reach higher and higher into the
corona until the heliosphere is reached
The Genesis of an Impulsive Coronal Mass Ejection observed at Ultra-High Cadence by AIA on SDO
The study of fast, eruptive events in the low solar corona is one of the
science objectives of the Atmospheric Imaging Assembly (AIA) imagers on the
recently launched Solar Dynamics Observatory (SDO), which take full disk images
in ten wavelengths with arcsecond resolution and 12 sec cadence. We study with
AIA the formation of an impulsive coronal mass ejection (CME) which occurred on
June 13, 2010 and was associated with an M1.0 class flare. Specifically, we
analyze the formation of the CME EUV bubble and its initial dynamics and
thermal evolution in the low corona using AIA images in three wavelengths (171,
193 and 211 A). We derive the first ultra-high cadence measurements of the
temporal evolution of the CME bubble aspect ratio
(=bubble-height/bubble-radius). Our main result is that the CME formation
undergoes three phases: it starts with a slow self-similar expansion followed
by a fast but short-lived (~ 70 sec) period of strong lateral over-expansion
which essentially creates the CME. Then the CME undergoes another phase of
self-similar expansion until it exits the AIA field of view. During the studied
interval, the CME height-time profile shows a strong, short-lived, acceleration
followed by deceleration. The lateral overexpansion phase coincides with the
deceleration phase. The impulsive flare heating and CME acceleration are
closely coupled. However, the lateral overexpansion of the CME occurs during
the declining phase and is therefore not linked to flare reconnection. In
addition, the multi-thermal analysis of the bubble does not show significant
evidence of temperature change.Comment: 2010 in pres
Coronal Mass Ejection Detection using Wavelets, Curvelets and Ridgelets: Applications for Space Weather Monitoring
Coronal mass ejections (CMEs) are large-scale eruptions of plasma and
magnetic feld that can produce adverse space weather at Earth and other
locations in the Heliosphere. Due to the intrinsic multiscale nature of
features in coronagraph images, wavelet and multiscale image processing
techniques are well suited to enhancing the visibility of CMEs and supressing
noise. However, wavelets are better suited to identifying point-like features,
such as noise or background stars, than to enhancing the visibility of the
curved form of a typical CME front. Higher order multiscale techniques, such as
ridgelets and curvelets, were therefore explored to characterise the morphology
(width, curvature) and kinematics (position, velocity, acceleration) of CMEs.
Curvelets in particular were found to be well suited to characterising CME
properties in a self-consistent manner. Curvelets are thus likely to be of
benefit to autonomous monitoring of CME properties for space weather
applications.Comment: Accepted for publication in Advances in Space Research (3 April 2010
Immunotherapy in Urothelial Cancer:Stop When Achieving a Response, Restart upon Disease Progression
Background: Since there is no clear consensus on optimal treatment duration of PD-(L)1 targeting checkpoint inhibitors in the setting of urothelial cancer (UC) patients, even patients with durable responses are often treated up to 2 years. It is questionable whether this is necessary and whether quality of life improves when treatment is discontinued earlier and restarted when necessary. Methods: We collected available data from locally advanced or metastatic UC patients within the Netherlands between September 2017 and December 2019 treated with first or second-line pembrolizumab, to evaluate treatment duration, reasons for discontinuation, subsequent treatments and survival outcomes. Results: Data were available from 74 patients: 85% (63/74) of patients had a treatment duration of 12 months or shorter, and in seven out of them, treatment was discontinued for another reason than progressive disease. Two patients (3%) had a treatment duration between 12 and 24 months, and eight patients (11%) completed 24 months of treatment. Survival at data cut-off (1 July 2020) with a median follow-up of 35 months was 100% in patients with partial or complete response (6/7 patients) and treatment duration ≤ 12 months, and 100% in patients treated for 24 months. In total, three patients were re-treated with pembrolizumab upon progressive disease during follow-up. Conclusions: In patients who reach partial or complete response during treatment with a PD-(L)1 targeting checkpoint inhibitor, early discontinuation of treatment with pembrolizumab and restart if necessary seems to be reasonable with preserved favorable outcomes. This article should drive further efforts to optimize the treatment duration for patients who respond to treatment with pembrolizumab.</p
Automated LASCO CME catalog for solar cycle 23: are CMEs scale invariant?
In this paper we present the first automatically constructed LASCO CME
catalog, a result of the application of the Computer Aided CME Tracking
software (CACTus) on the LASCO archive during the interval September 1997 -
January 2007. We have studied the CME characteristics and have compared them
with similar results obtained by manual detection (CDAW CME catalog). On
average CACTus detects less than 2 events per day during solar minimum up to 8
events during maximum, nearly half of them being narrow (< 20 degrees).
Assuming a correction factor, we find that the CACTus CME rate is surprisingly
consistent with CME rates found during the past 30 years. The CACTus statistics
show that small scale outflow is ubiquitously observed in the outer corona. The
majority of CACTus-only events are narrow transients related to previous CME
activity or to intensity variations in the slow solar wind, reflecting its
turbulent nature. A significant fraction (about 15%) of CACTus-{\it only}
events were identified as independent events, thus not related to other CME
activity. The CACTus CME width distribution is essentially scale invariant in
angular span over a range of scales from 20 to 120 degrees while previous
catalogues present a broad maximum around 30 degrees. The possibility that the
size of coronal mass outflows follow a power law distribution could indicate
that no typical CME size exists, i.e. that the narrow transients are not
different from the larger well-defined CMEs.Comment: 13 pages. ApJ, accepte
RTPrimerDB: the real-time PCR primer and probe database, major update 2006
The RTPrimerDB () project provides a freely accessible data retrieval system and an in silico assay evaluation pipeline for real-time quantitative PCR assays. Over the last year the number of user submitted assays has grown to 3500. Data conveyance from Entrez Gene by establishing an assay-to-gene relationship enables the addition of new primer assays for one of the 1.5 million different genes from 2300 species stored in the system. Easy access to the primer and probe data is possible by using multiple search criteria. Assay reports contain gene information, assay details (such as oligonucleotide sequences, detection chemistry and reaction conditions), publication information, users' experimental evaluation feedback and submitter's contact details. Gene expression assays are extended with a scalable assay viewer that provides detailed information on the alignment of primer and probe sequences on the known transcript variants of a gene, along with Single Nucleotide Polymorphisms (SNP) positions and peptide domain information. Furthermore, an mfold module is implemented to predict the secondary structure of the amplicon sequence, as this has been reported to impact the efficiency of the PCR. RTPrimerDB is also extended with an in silico analysis pipeline to streamline the evaluation of custom designed primer and probe sequences prior to ordering and experimental evaluation. In a secured environment, the pipeline performs automated BLAST specificity searches, mfold secondary structure prediction, SNP or plain sequence error identification, and graphical visualization of the aligned primer and probe sequences on the target gene
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