Relative field line helicity of a large eruptive solar active region

Context. Magnetic helicity is a physical quantity of great importance in the study of astrophysical and natural plasmas. Although a density for helicity cannot be defined, a good proxy for it is field line helicity. The appropriate quantity for use in solar conditions is relative field line helicity (RFLH). Aims. This work aims to study in detail the behaviour of RFLH, for the first time, in a solar active region (AR). Methods. The target active region is the large, eruptive AR 11158. In order to compute RFLH and all other quantities of interest we use a non-linear force-free reconstruction of the AR coronal magnetic field of excelent quality. Results. We find that the photospheric morphology of RFLH is quite different than that of the magnetic field or of the electrical current, and this is not sensitive to the chosen gauge in the computation of RFLH. The value of helicity experiences a large decrease, 25% of its pre-flare value, during an X-class flare of the AR, a change that is also depicted in the photospheric morphology of RFLH. Moreover, the area of this change coincides with the area that encompasses the flux rope, the magnetic structure that later erupted. Conclusions. The use of RFLH can provide important information about the value and location of the magnetic helicity expelled from the solar atmosphere during eruptive events.Comment: accepted by Astronomy & Astrophysic

Magnetic Helicity Estimations in Models and Observations of the Solar Magnetic Field. Part III: Twist Number Method

We study the writhe, twist and magnetic helicity of different magnetic flux ropes, based on models of the solar coronal magnetic field structure. These include an analytical force-free Titov--D\'emoulin equilibrium solution, non force-free magnetohydrodynamic simulations, and nonlinear force-free magnetic field models. The geometrical boundary of the magnetic flux rope is determined by the quasi-separatrix layer and the bottom surface, and the axis curve of the flux rope is determined by its overall orientation. The twist is computed by the Berger--Prior formula that is suitable for arbitrary geometry and both force-free and non-force-free models. The magnetic helicity is estimated by the twist multiplied by the square of the axial magnetic flux. We compare the obtained values with those derived by a finite volume helicity estimation method. We find that the magnetic helicity obtained with the twist method agrees with the helicity carried by the purely current-carrying part of the field within uncertainties for most test cases. It is also found that the current-carrying part of the model field is relatively significant at the very location of the magnetic flux rope. This qualitatively explains the agreement between the magnetic helicity computed by the twist method and the helicity contributed purely by the current-carrying magnetic field.Comment: To be published in Ap

The politics of deindustrialisation in France (1974-1984): the case of the textiles & clothing, steel and automobile industries

This thesis proposes an original understanding of deindustrialisation which it defines as a double-sided phenomenon that involves both industrial modernisation and contraction and as a process that is actively shaped by the state. The thesis’ central argument is that deindustrialisation can be understood as a form of industrial statecraft whereby state managers endorse a selective disengagement from certain manufacturing activities in order to rationalise the country’s industry and enhance its overall commercial performance. Drawing from an Open Marxist perspective this thesis contends that states, as the political form of capitalist social relations, are an integral instant of the process of capital valorisation and as a result are constrained by the necessity to guarantee the conditions for profitable accumulation within their borders and the national economy’s competitive insertion within the global market. To substantiate these claims, this thesis offers empirical evidence from the French national archives which traces the process of industrial policy-making between 1974 and 1984 towards three sectors: textiles & clothing, steel and automobiles. In France, faced with a global crisis of overaccumulation that domestically translated into a growing trade deficit, the consecutive governments of the decade under examination sought to selectively devalue the superfluous industrial capital that impeded the competitiveness of domestic industry on the world stage. In each of these sectors, government officials were faced with a policy quandary as the planned closures and ensuing unemployment that accompanied selective disengagement threatened to ignite widespread labour contestation. Thus, selective disengagement was carried out through diverse strategies that involved to different degrees the politicisation and/or depoliticisation of industrial policy. Such strategies sought to palliate the consequences of deindustrialisation and/or transfer the responsibilities over industrial adjustment to non-state spheres in order to ensure the conformity of domestic class relations with the general objectives of selective disengagement

Th17 cytokines disrupt the airway mucosal barrier in chronic rhinosinusitis

Cytokine mediated changes in paracellular permeability contribute to a multitude of pathological conditions including chronic rhinosinusitis (CRS). The purpose of this study was to investigate the effect of interferons and of Th1, Th2, and Th17 cytokines on respiratory epithelium barrier function. Cytokines and interferons were applied to the basolateral side of air-liquid interface (ALI) cultures of primary human nasal epithelial cells (HNECs) from CRS with nasal polyp patients. Transepithelial electrical resistance (TEER) and permeability of FITC-conjugated dextrans were measured over time. Additionally, the expression of the tight junction protein Zona Occludens-1 (ZO-1) was examined via immunofluorescence. Data was analysed using ANOVA, followed by Tukey HSD post hoc test. Our results showed that application of interferons and of Th1 or Th2 cytokines did not affect the mucosal barrier function. In contrast, the Th17 cytokines IL-17, IL-22, and IL-26 showed a significant disruption of the epithelial barrier, evidenced by a loss of TEER, increased paracellular permeability of FITC-dextrans, and discontinuous ZO-1 immunolocalisation. These results indicate that Th17 cytokines may contribute to the development of CRSwNP by promoting a leaky mucosal barrier.Mahnaz Ramezanpour, Sophia Moraitis, Jason L. P. Smith, P. J. Wormald, and Sarah Vreugd

In which shell-type SNRs should we look for gamma-rays and neutrinos from p-p collisions?

We present a simple analytic model for the various contributions to the non-thermal emission from shell type SNRs, and show that this model's results reproduce well the results of previous detailed calculations. We show that the \geq 1 TeV gamma ray emission from the shell type SNRs RX J1713.7-3946 and RX J0852.0-4622 is dominated by inverse-Compton scattering of CMB photons (and possibly infra-red ambient photons) by accelerated electrons. Pion decay (due to proton-proton collisions) is shown to account for only a small fraction, \lesssim10^-2, of the observed flux, as assuming a larger fractional contribution would imply nonthermal radio and X-ray synchrotron emission and thermal X-ray Bremsstrahlung emission that far exceed the observed radio and X-ray fluxes. Models where pion decay dominates the \geq 1 TeV flux avoid the implied excessive synchrotron emission (but not the implied excessive thermal X-ray Bremsstrahlung emission) by assuming an extremely low efficiency of electron acceleration, K_ep \lesssim 10^-4 (K_ep is the ratio of the number of accelerated electrons and the number of accelerated protons at a given energy). We argue that observations of SNRs in nearby galaxies imply a lower limit of K_ep \gtrsim 10^-3, and thus rule out K_ep values \lesssim 10^-4 (assuming that SNRs share a common typical value of K_ep). It is suggested that SNRs with strong thermal X-ray emission, rather than strong non-thermal X-ray emission, are more suitable candidates for searches of gamma rays and neutrinos resulting from proton-proton collisions. In particular, it is shown that the neutrino flux from the SNRs above is probably too low to be detected by current and planned neutrino observatories (Abridged).Comment: 13 pages, 1 figure, accepted for publication in JCAP, minor revision

Evaluation of magnetic resonance imaging abnormalities in juvenile onset neuropsychiatric systemic lupus erythematosus.

The aim of this study was to describe the abnormalities identified with conventional MRI in children with neuropsychiatric systemic lupus erythematosus (NPSLE). This was single-centre (Great Ormond Street Hospital, London) retrospective case series of patients with juvenile NPSLE seen in 2003-2013. Brain MR images of the first episode of active NPSLE were reviewed. All patients fulfilled the 1999 ACR case definitions for NPSLE syndromes. Presenting neuropsychiatric manifestations, immunological findings and treatment are reported. Results are expressed as median and ranges or percentages. Fisher's exact test was used to identify clinical predictors of abnormal MRI. A total of 27 patients (22 females), median age 11 years (4-15), were identified. Presenting clinical symptoms included the following: headaches (85.1 %), mood disorder/depression (62.9 %), seizures (22.2 %), acute psychosis (18.5 %), cognitive dysfunction (14.8 %), movement disorder (14.8 %), acute confusional state (14.8 %), aseptic meningitis (7.4 %), demyelinating syndrome (3.7 %), myelopathy (3.7 %), dysautonomia (3.7 %) and cranial neuropathy (3.7 %). The principal MR findings were as follows: (1) absence of MRI abnormalities despite signs and symptoms of active NPSLE (59 %); (2) basilar artery territory infarction (3 %); (3) focal white matter hyperintensities on T2-weighted imaging (33 %); (4) cortical grey matter lesions (3 %); and (5) brain atrophy (18.5 %). The presence of an anxiety disorder strongly associated with abnormal MRI findings (p = 0.008). In over half the children with NPSLE, no conventional MRI abnormalities were observed; white matter hyperintensities were the most commonly described abnormalities. Improved MR techniques coupled with other alternative diagnostic imaging modalities may improve the detection rate of brain involvement in juvenile NPSLE

Systemic juvenile idiopathic arthritis: The Great Ormond Street Hospital experience (2005–2021)

Systemic juvenile idiopathic arthritis (sJIA) is a complex, systemic inflammatory disorder driven by both innate and adaptive immunity. Improved understanding of sJIA pathophysiology has led to recent therapeutic advances including a growing evidence base for the earlier use of IL-1 or IL-6 blockade as first-line treatment. We conducted a retrospective case notes review of patients diagnosed with sJIA over a 16-year period (October 2005-October 2021) at Great Ormond Street Hospital for Children. We describe the clinical presentation, therapeutic interventions, complications, and remission rates at different timepoints over the disease course. We examined our data, which spanned a period of changing therapeutic landscape, to try and identify potential therapeutic signals in patients who received biologic treatment early in the disease course compared to those who did not. A total of 76-children (female n = 40, 53%) were diagnosed with sJIA, median age 4.5 years (range 0.6-14.1); 36% (27/76) presented with suspected or confirmed macrophage activation syndrome. A biologic disease-modifying anti-rheumatic drug (bDMARD) alone was commenced as first-line treatment in 28% (n = 21/76) of the cohort; however, at last review, 84% (n = 64/76) had received treatment with a bDMARD. Clinically inactive disease (CID) was achieved by 88% (n = 67/76) of the cohort at last review; however, only 32% (24/76) achieved treatment-free CID. At 1-year follow-up, CID was achieved in a significantly greater proportion of children who received treatment with a bDMARD within 3 months of diagnosis compared to those who did not (90% vs. 53%, p = 0.002). Based on an ever-increasing evidence base for the earlier use of bDMARD in sJIA and our experience of the largest UK single-centre case series described to date, we now propose a new therapeutic pathway for children diagnosed with sJIA in the UK based on early use of bDMARDs. Reappraisal of the current National Health Service commissioning pathway for sJIA is now urgently required

Effective induction therapy for anti-SRP associated myositis in childhood:A small case series and review of the literature

Background: Anti-Signal Recognition Particle associated myopathy is a clinically and histopathologically distinct subgroup of Juvenile Idiopathic Inflammatory Myositis, which is under-recognised in children and fails to respond to conventional first line therapies. We present three cases where remission was successfully induced using combination therapy with intensive rehabilitation. / Case presentations: Three new patients are reported. All 3 cases presented with profound, rapid-onset, proximal myopathy and markedly raised CK, but no rash. Histology revealed a destructive myopathy characterized by scattered atrophic and necrotic fibres with little or no inflammatory infiltrate. All 3 patients responded to induction with cyclophosphamide, IVIG and rituximab, in conjunction with intensive physiotherapy and methotrexate as the maintenance agent. Our patients regained near-normal strength (MMT > 70/80), in contrast with the current literature where >50% of cases reported severe residual weakness. / A literature search on paediatric anti-SRP myositis was performed to June 2016; PubMed was screened using a combination of the following terms: signal recognition particle, autoantibodies, antibodies, myositis, muscular diseases, skeletal muscle, childhood, paediatric, juvenile. Articles in a foreign language were excluded. Nine case studies were found. / Conclusion: This paper supports the hypothesis that anti-SRP myositis is distinct from other JIIM. It is an important differential to JDM and should be considered where there is severe weakness without rash or if highly elevated muscle enzymes (CK > 10,000 U/l) are found. Early identification is essential to initiate aggressive medical and physical therapy. Greater international collaboration and long-term follow-up data is needed to establish the most effective treatment strategy for this rare group of patients