112 research outputs found
Statistical analysis of solar H-alpha flares
A statistical analysis of a large data set of H-alpha flares comprising
almost 100000 single events that occurred during the period January 1975 to
December 1999 is presented. We analyzed the flares evolution steps, i.e.
duration, rise times, decay times and event asymmetries. Moreover, these
parameters characterizing the temporal behavior of flares, as well as the
spatial distribution on the solar disk, i.e. N-S and E-W asymmetries, are
analyzed in terms of their dependency on the solar cycle. The main results are:
1) The duration, rise and decay times increase with increasing importance
class. The increase is more pronounced for the decay times than for the rise
times. The same relation is valid with regard to the brightness classes but in
a weaker manner. 2) The event asymmetry indices, which characterize the
proportion of the decay to the rise time of an event, are predominantly
positive (90%). For about 50% of the events the decay time is even more than 4
times as long as the rise time. 3) The event asymmetries increase with the
importance class. 4) The flare duration and decay times vary in phase with the
solar cycle; the rise times do not. 5) The event asymmetries do not reveal a
distinct correlation with the solar cycle. However, they drop during times of
solar minima, which can be explained by the shorter decay times found during
minimum activity. 6) There exists a significant N-S asymmetry over longer
periods, and the dominance of one hemisphere over the other can persist for
more than one cycle. 7) For certain cycles there may be evidence that the N-S
asymmetry evolves with the solar cycle, but in general this is not the case. 8)
There exists a slight but significant E-W asymmetry with a prolonged eastern
excess.Comment: 13 pages, 11 figure
Temporal aspects and frequency distributions of solar soft X-ray flares
A statistical analysis of almost 50000 soft X-ray (SXR) flares observed by
GOES during the period 1976-2000 is presented. On the basis of this extensive
data set, statistics on temporal properties of soft X-ray flares, such as
duration, rise and decay times with regard to the SXR flare classes is
presented. Correlations among distinct flare parameters, i.e. SXR peak flux,
fluence and characteristic times, and frequency distributions of flare
occurrence as function of the peak flux, the fluence and the duration are
derived. We discuss the results of the analysis with respect to statistical
flare models, the idea of coronal heating by nanoflares, and elaborate on
implications of the obtained results on the Neupert effect in solar flares.Comment: 11 pages, 7 figure
Studying Sun-Planet Connections Using the Heliophysics Integrated Observatory (HELIO)
The Heliophysics Integrated Observatory (HELIO) is a software infrastructure involving a collection of web services, heliospheric data sources (e.g., solar, planetary, etc.), and event catalogues – all of which are accessible through a unified front end. In this paper we use the HELIO infrastructure to perform three case studies based on solar events that propagate through the heliosphere. These include a coronal mass ejection that intersects both Earth and Mars, a solar energetic particle event that crosses the orbit of Earth, and a high-speed solar wind stream, produced by a coronal hole, that is observed in situ at Earth (L1). A ballistic propagation model is run as one of the HELIO services and used to model these events, predicting if they will interact with a spacecraft or planet and determining the associated time of arrival. The HELIO infrastructure streamlines the method used to perform these kinds of case study by centralising the process of searching for and visualising data, indicating interesting features on the solar disk, and finally connecting remotely observed solar features with those detected by in situ solar wind and energetic particle instruments. HELIO represents an important leap forward in European heliophysics infrastructure by bridging the boundaries of traditional scientific domains
The Role of T Cell Immunity in Monoclonal Gammopathy and Multiple Myeloma: From Immunopathogenesis to Novel Therapeutic Approaches
Multiple Myeloma (MM) is a malignant growth of clonal plasma cells, typically arising from asymptomatic precursor conditions, namely monoclonal gammopathy of undetermined significance (MGUS) and smoldering MM (SMM). Profound immunological dysfunctions and cyto-kine deregulation are known to characterize the evolution of the disease, allowing immune escape and proliferation of neoplastic plasma cells. In the past decades, several studies have shown that the immune system can recognize MGUS and MM clonal cells, suggesting that anti-myeloma T cell immunity could be harnessed for therapeutic purposes. In line with this notion, chimeric antigen receptor T cell (CAR-T) therapy is emerging as a novel treatment in MM, especially in the re-lapsed/refractory disease setting. In this review, we focus on the pivotal contribution of T cell im-pairment in the immunopathogenesis of plasma cell dyscrasias and, in particular, in the disease progression from MGUS to SMM and MM, highlighting the potentials of T cell-based immunother-apeutic approaches in these settings
Early palliative care versus usual haematological care in multiple myeloma: retrospective cohort study
Objectives Although early palliative care (EPC) is beneficial in acute myeloid leukaemia, little is known about EPC value in multiple myeloma (MM). We compared quality indicators for palliative and end of life (EOL) care in patients with MM receiving EPC with those of patients who received usual haematological care (UHC).Methods This observational, retrospective study was based on 290 consecutive patients with MM. The following indicators were abstracted: providing psychological support, assessing/managing pain, discussing goals of care, promoting advance care plan, accessing home care services; no anti MM treatment within 14 and 30 days and hospice length of stay >7 days before death; no cardiopulmonary resuscitation, no intubation, <2 hospitalisations and emergency department visits within 30 days before death. Comparisons were performed using unadjusted and confounder adjusted regression models.Results 55 patients received EPC and 231 UHC. Compared with UHC patients, EPC patients had a significantly higher number of quality indicators of care (mean 2.62 +/- 1.25 vs 1.12 +/- 0.95; p<0.0001)); a significant reduction of pain intensity over time (p<0.01) and a trend towards reduced aggressiveness at EOL, with the same survival (5.3 vs 5.46 years; p=0.74)).Conclusions Our data support the value of integrating EPC into MM routine practice and lay the groundwork for future prospective comparative studies
Study of solar brightness profiles in the 18-26 GHz frequency range with INAF radio telescopes I: solar radius
The Sun is an extraordinary workbench, from which several fundamental
astronomical parameters can be measured with high precision. Among these
parameters, the solar radius plays an important role in several
aspects, such as in evolutionary models. Despite the efforts in obtaining
accurate measurements of , the subject is still debated and
measurements are puzzling and/or lacking in many frequency ranges. We aimed to
determine the mean, equatorial, and polar radii of the Sun (, ,
and ) in the frequency range 18.1 - 26.1 GHz. We employed single-dish
observations from the newly-appointed Medicina "Gavril Grueff" Radio Telescope
and the Sardinia Radio Telescope (SRT) throughout 5 years, from 2018 to
mid-2023, in the framework of the SunDish project for solar monitoring. Two
methods to calculate the radius at radio frequencies are considered and
compared. To assess the quality of our radius determinations, we also analysed
the possible degrading effects of the antenna beam pattern on our solar maps,
using two 2D-models. We carried out a correlation analysis with the evolution
of the solar cycle through the calculation of Pearson's correlation coefficient
. We obtained several values for the solar radius - ranging between 959
and 994 arcsec - and , with typical errors of a few arcsec. Our
measurements, consistent with values reported in literature,
suggest a weak prolatness of the solar limb ( > ), although
and are statistically compatible within 3 errors.
The correlation analysis using the solar images from Grueff shows (1) a
positive correlation between the solar activity and the temporal variation of
(and ) at all observing frequencies, and (2) a weak
anti-correlation between the temporal variation of and the solar
activity at 25.8 GHz.Comment: 18 pages, 12 figures, 6 tables, accepted by A&A; v
In-flight radiometric calibration of the Metis Visible Light channel using stars and comparison with STEREO-A/COR2 data
Context. We present the results for the in-flight radiometric calibration performed for the Visible Light (VL) channel of the Metis coronagraph on board Solar Orbiter. Aims. The radiometric calibration is a fundamental step in building the official pipeline of the instrument, devoted to producing the calibrated data in physical units (L2 data). Methods. To obtain the radiometric calibration factor (ÏμVL), we used stellar targets transiting the Metis field of view. We derived ÏμVLby determining the signal of each calibration star by means of the aperture photometry and calculating its expected flux in the Metis band pass. The analyzed data set covers the time range from the beginning of the Cruise Phase of the mission (June 2020) until March 2021. Results. Considering the uncertainties, the estimated factor ÏμVLis in a good agreement with that obtained during the on-ground calibration campaign. This implies that up to March 2021 there was no measurable reduction in the VL channel throughput. Finally, we compared the total and polarized brightness visible light images of the solar corona acquired with Metis and STEREO-A/COR2 during the November 2020 superior conjunction of these instruments. A general good agreement was obtained between the images of these instruments for both the total and polarized brightness
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