A study of magnetic reconnection in near-Earth space

Magnetic reconnection is a fundamental process by which two plasmas with different magnetic fields interact, changing the magnetic field topology, and transferring energy from the magnetic field to particles, resulting in electron and ion acceleration and heating. It is a multi-scale process: the small spatial and temporal scales are strongly coupled with the large scales. Although magnetic reconnection can be individuated in a bunch of different situation in space plasmas, we are interested in reconnection processes driven by the interaction between the solar wind and the magnetosphere. This work focuses on asymmetric reconnection - in which the two reconnection plasmas have different features - produced at Earth's magnetopause. In this study, we propose a study of magnetic reconnection focused on the microphysics of the process, which is still poorly understood. In particular, we investigate the relative contributions of various terms in the generalized Ohm's law by means of \textit{in situ} measurements by the Magnetospheric Multiscale (MMS) mission. MMS is a NASA four-spacecraft constellation mission launched in 2015 with the aim to conduct a definitive experiment to determine the causes of collisionless magnetic reconnection. The evaluation of Ohm's law has always been a challenge because of the lack of high resolution data preventing the achievement of a proper computation of the electron scale terms of Ohm's law. Indeed, the computation of the pressure and the inertia term using in situ measurements has never been achieved with data from previous missions. We consider the event of October, 3 2015 in which several consecutive magnetopause crossings occurred. Around 1500 UTC the MMS satellites were located in the afternoon side of magnetosphere and separated by a distance of about 20 km. The analysis focuses in particular on two consecutive complete crossings: during the first crossing signatures of reconnection are observed while these are absent in the second one. We report an encounter with an ion diffusion region. Then, we compute of all the terms of the generalised Ohm's law. Since the spacecraft did not cross the electron diffusion region, we expect the inertia and the pressure terms to be negligible compared to the others. This is what is found at the end of the analysis: the reconnection electric field is mainly sustained by the Hall term in presence of reconnection; ideal Ohm's law holds when reconnection stops

Serology of Lupus Erythematosus: Correlation between Immunopathological Features and Clinical Aspects

Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by the aberrant production of a broad and heterogenous group of autoantibodies. Even though the presence of autoantibodies in SLE has been known, for more than 60 years, still nowadays a great effort is being made to understand the pathogenetic, diagnostic, and prognostic meaning of such autoantibodies. Antibodies to ds-DNA are useful for the diagnosis of SLE, to monitor the disease activity, and correlate with renal and central nervous involvements. Anti-Sm antibodies are highly specific for SLE. Anti-nucleosome antibodies are an excellent marker for SLE and good predictors of flares in quiescent lupus. Anti-histone antibodies characterize drug-induced lupus, while anti-SSA/Ro and anti-SSB/La antibodies are associated with neonatal lupus erythematosus and photosensitivity. Anti-ribosomal P antibodies play a role in neuropsychiatric lupus, but their association with clinical manifestations is still unclear. Anti-phospholipid antibodies are associated with the anti-phospholipid syndrome, cerebral vascular disease, and neuropsychiatric lupus. Anti-C1q antibodies amplify glomerular injury, and the elevation of their titers may predict renal flares. Anti-RNP antibodies are a marker of Sharp’s syndrome but can be found in SLE as well. Anti-PCNA antibodies are present in 5–10% of SLE patients especially those with arthritis and hypocomplementemia

Birth month and adult lifespan : a within-family, cohort, and spatial examination using FamiLinx data in the United States (1700-1899)

Background: Research has shown that the circumstances surrounding birth may influence the timing of death. In the northern hemisphere, children born in spring and summer have a shorter lifespan than those born in fall and winter. Objective: We describe the effect of month of birth on adult lifespan (50+) in the United States in three ways. First, we estimate it between and within groups of siblings, accounting for unobserved factors at the family level. Second, we estimate the effect of birth month across a period of about 200 years (1700‒1899). Third, we examine geographical variation in the effect of birth month across US census areas. Method: We estimate descriptive statistics and OLS regression models between and within sibling groups.Results: we find an effect of birth month on lifespan. Individuals born in spring and summer have on average a shorter lifespan than those born in fall and winter. The effect is relatively consistent across cohorts, geographical census areas, and between and within families. We test different possible explanations for this result and find residual evidence that in utero debilitation may account for this result

Birth month and adult lifespan: A within-family, cohort, and spatial examination using FamiLinx data in the United States (1700-1899)

Background: Research has shown that the circumstances surrounding birth may influence the timing of death. In the northern hemisphere, children born in spring and summer have a shorter lifespan than those born in fall and winter. Objective: We describe the effect of month of birth on adult lifespan (50+) in the United States in three ways. First, we estimate it between and within groups of siblings, accounting for unobserved factors at the family level. Second, we estimate the effect of birth month across a period of about 200 years (1700‒1899). Third, we examine geographical variation in the effect of birth month across US census areas. Methods: We estimate descriptive statistics and OLS regression models between and within sibling groups. Results: We find an effect of birth month on lifespan. Individuals born in spring and summer have on average a shorter lifespan than those born in fall and winter. The effect is relatively consistent across cohorts, geographical census areas, and between and within families. We test different possible explanations for this result and find residual evidence that in utero debilitation may account for this result. Contribution: Twenty years ago, Gabriele Doblhammer and James W. Vaupel published an influential paper, showing the importance of birth month for lifespan and arguing that circumstances experienced in utero are the likely explanation for this result. We extend these insights by exploiting new crowdsourced data that allows us to study the phenomena over 200 years, across space, and between and within families

Fragments Generated During Liquid Hydrogen Tank Explosions

Liquid hydrogen (LH2) may be employed to transport large quantities of pure hydrogen or be stored onboard of ships, airplanes and trains fuelled by hydrogen, thanks to its high density compared to gaseous compressed hydrogen. LH2 is a cryogenic fluid with an extremely low boiling point (-253°C at atmospheric pressure) that must be stored in double-walled vacuum insulated tanks to limit the boil-off formation. There is limited knowledge on the consequences of LH2 tanks catastrophic rupture. In fact, the yield of the consequences of an LH2 tank explosion (pressure wave, fragments and fireball) depend on many parameters such as tank dimension, filling degree, and tank internal conditions (temperature and pressure) prior the rupture. Only two accidents provoked by the rupture of an LH2 tank occurred in the past and a couple of experimental campaigns focussed on this type of accident scenario were carried out for LH2. The aim of this study is to analyse one of the LH2 tank explosion consequences namely the fragments. The longest horizontal and vertical ranges of the fragments thrown away from the blast wave are estimated together with the spatial distribution around the tank. Theoretical models are adopted in this work and validated with the experimental results. The proposed models can aid the risk analysis of LH2 storage technologies and provide critical insights to plan a prevention and mitigation strategy and improve the safety of hydrogen applications

Modelling of Fireballs Generated After the Catastrophic Rupture of Hydrogen Tanks

The interest towards hydrogen skyrocketed in the last years. Thanks to its potential as an energy carrier, hydrogen will be soon handled in public and densely populated areas. Therefore, accurate models are necessary to predict the consequences of unwanted scenarios. These new models should be employed in the consequence analysis, a phase of risk assessment, and thus aid the selection, implementation, and optimization of effective risk-reducing measures. This will increase safety of hydrogen technologies and therefore favour their deployment on a larger scale. Hydrogen is known to be an extremely flammable gas with a low radiation flame compared to hydrocarbons. However, luminous fireballs were generated after the rupture of both compressed gaseous and liquid hydrogen tanks in many experiments. Moreover, it was demonstrated that conventional empirical correlations, initially developed for hydrocarbon fuels, underestimate both dimension and duration of hydrogen fireballs recorded during small-scale tests (Ustolin and Paltrinieri, 2020). The aim of this study is to obtain an analysis of hydrogen fireballs to provide new critical insights for consequence analysis. A comparison among different correlations is conducted when predicting fireball characteristics during the simulation of past experiments where both gaseous and liquid hydrogen tanks were intentionally destroyed. All the models employed in this study are compared with the experimental results for validation purposes. Specific models designed for hydrogen can support the design of hydrogen systems and increasing their safety and promote their future distribution

ViDA: a VlasovDArwin solver for plasma physics at electron scales

We present a Vlasov–DArwin numerical code (ViDA) specifically designed to address plasma physics problems, where small-scale high accuracy is requested even during the nonlinear regime to guarantee a clean description of the plasma dynamics at fine spatial scales. The algorithm provides a low-noise description of proton and electron kinetic dynamics, by splitting in time the multi-advection Vlasov equation in phase space. Maxwell equations for the electric and magnetic fields are reorganized according to the Darwin approximation to remove light waves. Several numerical tests show that ViDA successfully reproduces the propagation of linear and nonlinear waves and captures the physics of magnetic reconnection. We also discuss preliminary tests of the parallelization algorithm efficiency, performed at CINECA on the Marconi-KNL cluster. ViDA will allow the running of Eulerian simulations of a non-relativistic fully kinetic collisionless plasma and it is expected to provide relevant insights into important problems of plasma astrophysics such as, for instance, the development of the turbulent cascade at electron scales and the structure and dynamics of electron-scale magnetic reconnection, such as the electron diffusion region

Environmental factors in autoimmune bullous diseases with focusing on seasonality: new insights

Autoimmune bullous diseases are a heterogeneous group of rare conditions clinically characterized by the presence of blisters and/or erosions on the skin and on the mucous membranes. Practically, they can be divided into two large groups: the pemphigoid group and the pemphigus group, depending on the depth of the autoimmune process on the skin. Family history of autoimmune disease can often be found, and demonstrating that genetic predisposition is crucial in the development of them. Moreover, numerous environmental risk factors, such as solar radiation, drugs and infections, are known. This study aimed to evaluate how seasonality can affect the trend of BP and PV, especially considering the number of hospitalizations recorded over the course of individual months. The total number of hospitalizations in the twelve months of the year was evaluated. Further, blood chemistry assay and, for some patients, enzyme-linked immunosorbent assay were executed in order to evaluate antibodies. Regarding the severity of the disease BPDAI (Bullous Pemphigoid Area Index) and PDAI (Pemphigus Disease Area Index), score systems were used. Results showed a complex interplay between environmental factors such as seasons and autoimmune conditions

Spatial filtering in a 6D hybrid-Vlasov scheme to alleviate adaptive mesh refinement artifacts : a case study with Vlasiator (versions 5.0, 5.1, and 5.2.1)

Numerical simulation models that are used to investigate the near-Earth space plasma environment require sophisticated methods and algorithms as well as high computational power. Vlasiator 5.0 is a hybrid-Vlasov plasma simulation code that is able to perform 6D (3D in ordinary space and 3D in velocity space) simulations using adaptive mesh refinement (AMR). In this work, we describe a side effect of using AMR in Vlasiator 5.0: the heterologous grid approach creates discontinuities due to the different grid resolution levels. These discontinuities cause spurious oscillations in the electromagnetic fields that alter the global results. We present and test a spatial filtering operator for alleviating this artifact without significantly increasing the computational overhead. We demonstrate the operator's use case in large 6D AMR simulations and evaluate its performance with different implementations.Peer reviewe