120 research outputs found
Kinematic active region formation in a three-dimensional solar dynamo model
We propose a phenomenological technique for modelling the emergence of active regions within a three-dimensional, kinematic dynamo framework. By imposing localized velocity perturbations, we create emergent flux tubes out of toroidal magnetic field at the base of the convection zone, leading to the eruption of active regions at the solar surface. The velocity perturbations are calibrated to reproduce observed active region properties (including the size and flux of active regions, and the distribution of tilt angle with latitude), resulting in a more consistent treatment of flux-tube emergence in kinematic dynamo models than artificial flux deposition. We demonstrate how this technique can be used to assimilate observations and drive a kinematic three-dimensional model, and use it to study the characteristics of active region emergence and decay as a source of poloidal field.We find that the poloidal components are strongest not at the solar surface, but in the middle convection zone, in contrast with the common assumption that the poloidal source is located near the solar surface. We also find that, while most of the energy is contained in the lower convection zone, there is a good correlation between the evolution of the surface and interior magnetic fields
MEMPSEP II. -- Forecasting the Properties of Solar Energetic Particle Events using a Multivariate Ensemble Approach
Solar Energetic Particles (SEPs) form a critical component of Space Weather.
The complex, intertwined dynamics of SEP sources, acceleration, and transport
make their forecasting very challenging. Yet, information about SEP arrival and
their properties (e.g., peak flux) is crucial for space exploration on many
fronts. We have recently introduced a novel probabilistic ensemble model called
the Multivariate Ensemble of Models for Probabilistic Forecast of Solar
Energetic Particles (MEMPSEP). Its primary aim is to forecast the occurrence
and physical properties of SEPs. The occurrence forecasting, thoroughly
discussed in a preceding paper (Chatterjee et al., 2023), is complemented by
the work presented here, which focuses on forecasting the physical properties
of SEPs. The MEMPSEP model relies on an ensemble of Convolutional Neural
Networks, which leverage a multi-variate dataset comprising full-disc
magnetogram sequences and numerous derived and in-situ data from various
sources. Skill scores demonstrate that MEMPSEP exhibits improved predictions on
SEP properties for the test set data with SEP occurrence probability above 50%,
compared to those with a probability below 50%. Results present a promising
approach to address the challenging task of forecasting SEP physical
properties, thus improving our forecasting capabilities and advancing our
understanding of the dominant parameters and processes that govern SEP
production
On the Amplitude of Convective Velocities in the Deep Solar Interior
We obtain lower limits on the amplitude of convective velocities in the deep
solar convection zone based only on the observed properties of the differential
rotation and meridional circulation together with simple and robust dynamical
balances obtained from the fundamental MHD equations. The linchpin of the
approach is the concept of gyroscopic pumping whereby the meridional
circulation across isosurfaces of specific angular momentum is linked to the
angular momentum transport by the convective Reynolds stress. We find that the
amplitude of the convective velocity must be at least 30 m s in the
upper CZ () and at least 8 m s in the lower CZ () in order to be consistent with the observed mean flows. Using the base
of the near-surface shear layer as a probe of the rotational influence, we are
further able to show that the characteristic length scale of deep convective
motions must be no smaller than 5.5--30 Mm. These results are compatible with
convection models but suggest that the efficiency of the turbulent transport
assumed in advection-dominated flux-transport dynamo models is generally not
consistent with the mean flows they employ.Comment: 16 pages, 4 figures, accepted to the Astrophysical Journa
Infrastructure for Detector Research and Development towards the International Linear Collider
The EUDET-project was launched to create an infrastructure for developing and
testing new and advanced detector technologies to be used at a future linear
collider. The aim was to make possible experimentation and analysis of data for
institutes, which otherwise could not be realized due to lack of resources. The
infrastructure comprised an analysis and software network, and instrumentation
infrastructures for tracking detectors as well as for calorimetry.Comment: 54 pages, 48 picture
Total cardiovascular or fatal events in people with type 2 diabetes and cardiovascular risk factors treated with dulaglutide in the REWIND trail:a post hoc analysis
Abstract
Background
The Researching cardiovascular Events with a Weekly INcretin in Diabetes (REWIND) double blind randomized trial demonstrated that weekly subcutaneous dulaglutide 1.5Â mg, a glucagon like peptide-1 receptor agonist, versus matched placebo reduced the first outcome of major adverse cardiovascular event (MACE), cardiovascular death, nonfatal myocardial infarction or nonfatal stroke (594 versus 663 events) in 9901 persons with type 2 diabetes and either chronic cardiovascular disease or risk factors, and followed during 5.4Â years. These findings were based on a time-to-first-event analysis and preclude relevant information on the burden of total major events occurring during the trial. This analysis reports on the total cardiovascular or fatal events in the REWIND participants
Methods
We compared the total incidence of MACE or non-cardiovascular deaths, and the total incidence of expanded MACE (MACE, unstable angina, heart failure or revascularization) or non-cardiovascular deaths between participants randomized to dulaglutide and those randomized to placebo. Incidences were expressed as number per 1000 person-years. Hazard ratios (HR) were calculated using the conditional time gap and proportional means models.
Results
Participants had a mean age of 66.2 years, 46.3% were women and 31% had previous cardiovascular disease. During the trial there were 1972 MACE or non-cardiovascular deaths and 3673 expanded MACE or non-cardiovascular deaths. The incidence of total MACE or non-cardiovascular deaths in the dulaglutide and placebo groups was 35.8 and 40.3 per 1000 person-years, respectively [absolute reduction = 4.5 per 1000 person-years; conditional time gap HR 0.90 (95% CI, 0.82–0.98) p = 0.020, and proportional means HR 0.89 (95% CI, 0.80–0.98) p = 0.022]. The incidence of total expanded MACE or non-cardiovascular deaths in the dulaglutide and placebo groups was 67.1 and 74.7 per 1000 person-years, respectively [absolute reduction = 7.6 per 1000 person-years; conditional time gap HR 0.93 (95% CI, 0.87–0.99) p = 0.023, and proportional means HR 0.90 (95% CI, 0.82–0.99) p = 0.028].
Conclusions
These findings suggest that weekly subcutaneous dulaglutide reduced total cardiovascular or fatal event burden in people with type 2 diabetes at moderate cardiovascular risk.
Clinical Trial Registration:
https://www.clinicaltrials.gouv
. Unique Identifier NCT01394952)
The MoS2 Nanotubes with Defect-Controlled Electric Properties
We describe a two-step synthesis of pure multiwall MoS2 nanotubes with a high degree of homogeneity in size. The Mo6S4I6 nanowires grown directly from elements under temperature gradient conditions in hedgehog-like assemblies were used as precursor material. Transformation in argon-H2S/H2 mixture leads to the MoS2 nanotubes still grouped in hedgehog-like morphology. The described method enables a large-scale production of MoS2 nanotubes and their size control. X-ray diffraction, optical absorption and Raman spectroscopy, scanning electron microscopy with wave dispersive analysis, and transmission electron microscopy were used to characterize the starting Mo6S4I6 nanowires and the MoS2 nanotubes. The unit cell parameters of the Mo6S4I6 phase are proposed. Blue shift in optical absorbance and metallic behavior of MoS2 nanotubes in two-probe measurement are explained by a high defect concentration
Neonatal infections: Case definition and guidelines for data collection, analysis, and presentation of immunisation safety data.
Maternal vaccination is an important area of research and requires appropriate and internationally comparable definitions and safety standards. The GAIA group, part of the Brighton Collaboration was created with the mandate of proposing standardised definitions applicable to maternal vaccine research. This study proposes international definitions for neonatal infections. The neonatal infections GAIA working group performed a literature review using Medline, EMBASE and the Cochrane collaboration and collected definitions in use in neonatal and public health networks. The common criteria derived from the extensive search formed the basis for a consensus process that resulted in three separate definitions for neonatal blood stream infections (BSI), meningitis and lower respiratory tract infections (LRTI). For each definition three levels of evidence are proposed to ensure the applicability of the definitions to different settings. Recommendations about data collection, analysis and presentation are presented and harmonized with the Brighton Collaboration and GAIA format and other existing international standards for study reporting
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