| 1. |
|
|
| 2. |
- Elhai, M, et al.
(författare)
-
Outcomes of patients with systemic sclerosis treated with rituximab in contemporary practice: a prospective cohort study
- 2019
-
Ingår i: Annals of the rheumatic diseases. - : BMJ. - 1468-2060 .- 0003-4967. ; 78:7, s. 979-987
-
Tidskriftsartikel (refereegranskat)abstract
- To assess the safety and efficacy of rituximab in systemic sclerosis (SSc) in clinical practice.MethodsWe performed a prospective study including patients with SSc from the European Scleroderma Trials and Research (EUSTAR) network treated with rituximab and matched with untreated patients with SSc. The main outcomes measures were adverse events, skin fibrosis improvement, lung fibrosis worsening and steroids use among propensity score-matched patients treated or not with rituximab.Results254 patients were treated with rituximab, in 58% for lung and in 32% for skin involvement. After a median follow-up of 2 years, about 70% of the patients had no side effect. Comparison of treated patients with 9575 propensity-score matched patients showed that patients treated with rituximab were more likely to have skin fibrosis improvement (22.7 vs 14.03 events per 100 person-years; OR: 2.79 [1.47–5.32]; p=0.002). Treated patients did not have significantly different rates of decrease in forced vital capacity (FVC)>10% (OR: 1.03 [0.55–1.94]; p=0.93) nor in carbon monoxide diffusing capacity (DLCO) decrease. Patients having received rituximab were more prone to stop or decrease steroids (OR: 2.34 [1.56–3.53], p<0.0001). Patients treated concomitantly with mycophenolate mofetil had a trend for better outcomes as compared with patients receiving rituximab alone (delta FVC: 5.22 [0.83–9.62]; p=0.019 as compared with controls vs 3 [0.66–5.35]; p=0.012).ConclusionRituximab use was associated with a good safety profile in this large SSc-cohort. Significant change was observed on skin fibrosis, but not on lung. However, the limitation is the observational design. The potential stabilisation of lung fibrosis by rituximab has to be addressed by a randomised trial.
|
|
| 3. |
|
|
| 4. |
|
|
| 5. |
- Becker, M, et al.
(författare)
-
Predictors of disease worsening defined by progression of organ damage in diffuse systemic sclerosis: a European Scleroderma Trials and Research (EUSTAR) analysis
- 2019
-
Ingår i: Annals of the rheumatic diseases. - : BMJ. - 1468-2060 .- 0003-4967. ; 78:9, s. 1242-1248
-
Tidskriftsartikel (refereegranskat)abstract
- Mortality and worsening of organ function are desirable endpoints for clinical trials in systemic sclerosis (SSc). The aim of this study was to identify factors that allow enrichment of patients with these endpoints, in a population of patients from the European Scleroderma Trials and Research group database.MethodsInclusion criteria were diagnosis of diffuse SSc and follow-up over 12±3 months. Disease worsening/organ progression was fulfilled if any of the following events occurred: new renal crisis; decrease of lung or heart function; new echocardiography-suspected pulmonary hypertension or death. In total, 42 clinical parameters were chosen as predictors for the analysis by using (1) imputation of missing data on the basis of multivariate imputation and (2) least absolute shrinkage and selection operator regression.ResultsOf 1451 patients meeting the inclusion criteria, 706 had complete data on outcome parameters and were included in the analysis. Of the 42 outcome predictors, eight remained in the final regression model. There was substantial evidence for a strong association between disease progression and age, active digital ulcer (DU), lung fibrosis, muscle weakness and elevated C-reactive protein (CRP) level. Active DU, CRP elevation, lung fibrosis and muscle weakness were also associated with a significantly shorter time to disease progression. A bootstrap validation step with 10 000 repetitions successfully validated the model.ConclusionsThe use of the predictive factors presented here could enable cohort enrichment with patients at risk for overall disease worsening in SSc clinical trials.
|
|
| 6. |
|
|
| 7. |
- Diaz-Gallo, L. M., et al.
(författare)
-
Analysis of the influence of PTPN22 gene polymorphisms in systemic sclerosis
- 2011
-
Ingår i: Annals of the Rheumatic Diseases. - : BMJ. - 1468-2060 .- 0003-4967. ; 70:3, s. 454-462
-
Tidskriftsartikel (refereegranskat)abstract
- Objective Two functional single nucleotide polymorphisms (SNP) in the PTPN22 gene (rs24746601 and rs33996649) have been associated with autoimmunity. The aim of this study was to investigate the role of the R263Q SNP for the first time and to re-evaluate the role of the R620W SNP in the genetic predisposition to systemic sclerosis (SSc) susceptibility and clinical phenotypes. Methods 3422 SSc patients (2020 with limited cutaneous SSc and 1208 with diffuse cutaneous SSc) and 3638 healthy controls of Caucasian ancestry from an initial case--control set of Spain and seven additional independent replication cohorts were included in our study. Both rs33996649 and rs2476601 PTPN22 polymorphisms were genotyped by TaqMan allelic discrimination assay. A meta-analysis was performed to test the overall effect of these PTPN22 polymorphisms in SSc. Results The meta-analysis revealed evidence of association of the rs2476601 T allele with SSc susceptibility (p(FDRcorrected) = 0.03 pooled, OR 1.15, 95% CI 1.03 to 1.28). In addition, the rs2476601 T allele was significantly associated with anticentromere-positive status (p(FDRcorrected) = 0.02 pooled, OR 1.22, 95% CI 1.05 to 1.42). Although the rs33996649 A allele was significantly associated with SSc in the Spanish population (p(FDRcorrected) = 0.04, OR 0.58, 95% CI 0.36 to 0.92), this association was not confirmed in the meta-analysis (p = 0.36 pooled, OR 0.89, 95% CI 0.72 to 1.1). Conclusion The study suggests that the PTPN22 R620W polymorphism influences SSc genetic susceptibility but the novel R263Q genetic variant does not. These data strengthen evidence that the R620W mutation is a common risk factor in autoimmune diseases.
|
|
| 8. |
- Distler, J. H. W., et al.
(författare)
-
Is there a role for TNF-alpha antagonists in the treatment of SSc? EUSTAR expert consensus development using the Delphi technique
- 2011
-
Ingår i: Clinical and Experimental Rheumatology. - 1593-098X. ; 29:2, s. 40-45
-
Tidskriftsartikel (refereegranskat)abstract
- Objective: To obtain experiences and expert opinion on treatment of SSc patients with TNF-alpha antagonists. Methods: An investigation was carried out among the EUSTAR centres into their expertise on use of TNF-alpha antagonists. Assessment forms on the frequency of TNF-alpha inhibitor use were distributed to EULAR Scleroderma Trials and Research Group (EUSTAR) centres. Afterwards, a three round Delphi exercise was performed to obtain expert consensus on the use of TNF-alpha inhibitors in SSc. Results: Seventy-nine centres returned information on use of TNF-alpha antagonists in SSc patients. A total of 65 patients were treated with TNF-alpha inhibitors in 14 different centres. Forty-eight of the 65 patients treated with TNF-alpha inhibitors improved. Improvement was mainly seen in patients with arthritis, whereas the effects on fibrosis varied. In the first round of the subsequent Delphi approach, 71 out of 79 experts stated that they would use TNF-alpha antagonists in SSc. Arthritis was suggested as an indication for TNF alpha antagonists by 75% of the experts. However; after the third stage of the Delphi exercise, the acceptance for the off-label use of TNF-alpha antagonists decreased and 59% recommended that TNF-alpha antagonists should not be used or only used in clinical trials in SSc patients, while 38% of the experts suggested the use of TNF-alpha antagonists for arthritis associated with SSc. Conclusions: Most of the experts do not recommend the routine use of TNF-alpha antagonists in systemic sclerosis. Arthritis might be a potential indication in SSc, although controlled clinical trials with TNF-alpha antagonists are needed before general recommendations can be given.
|
|
| 9. |
|
|
| 10. |
- Soucek, J., et al.
(författare)
-
EMC Aspects Of Turbulence Heating Observer (THOR) Spacecraft
- 2016
-
Ingår i: Proceedings Of 2016 Esa Workshop On Aerospace Emc (Aerospace Emc). - : Institute of Electrical and Electronics Engineers (IEEE). - 9789292213039
-
Konferensbidrag (refereegranskat)abstract
- Turbulence Heating ObserveR (THOR) is a spacecraft mission dedicated to the study of plasma turbulence in near-Earth space. The mission is currently under study for implementation as a part of ESA Cosmic Vision program. THOR will involve a single spinning spacecraft equipped with state of the art instruments capable of sensitive measurements of electromagnetic fields and plasma particles. The sensitive electric and magnetic field measurements require that the spacecraft-generated emissions are restricted and strictly controlled; therefore a comprehensive EMC program has been put in place already during the study phase. The THOR study team and a dedicated EMC working group are formulating the mission EMC requirements already in the earliest phase of the project to avoid later delays and cost increases related to EMC. This article introduces the THOR mission and reviews the current state of its EMC requirements.
|
|
| 11. |
- Vaivads, Andris, et al.
(författare)
-
Turbulence Heating ObserveR - satellite mission proposal
- 2016
-
Ingår i: JOURNAL OF PLASMA PHYSICS. - 0022-3778. ; 82
-
Tidskriftsartikel (refereegranskat)abstract
- The Universe is permeated by hot, turbulent, magnetized plasmas. Turbulent plasma is a major constituent of active galactic nuclei, supernova remnants, the intergalactic and interstellar medium, the solar corona, the solar wind and the Earth's magnetosphere, just to mention a few examples. Energy dissipation of turbulent fluctuations plays a key role in plasma heating and energization, yet we still do not understand the underlying physical mechanisms involved. THOR is a mission designed to answer the questions of how turbulent plasma is heated and particles accelerated, how the dissipated energy is partitioned and how dissipation operates in different regimes of turbulence. THOR is a single-spacecraft mission with an orbit tuned to maximize data return from regions in near-Earth space - magnetosheath, shock, foreshock and pristine solar wind - featuring different kinds of turbulence. Here we summarize the THOR proposal submitted on 15 January 2015 to the 'Call for a Medium-size mission opportunity in ESAs Science Programme for a launch in 2025 (M4)'. THOR has been selected by European Space Agency (ESA) for the study phase.
|
|
| 12. |
- Acosta-Herrera, M, et al.
(författare)
-
Genome-wide meta-analysis reveals shared new loci in systemic seropositive rheumatic diseases
- 2019
-
Ingår i: Annals of the rheumatic diseases. - : BMJ. - 1468-2060 .- 0003-4967. ; 78:3, s. 311-319
-
Tidskriftsartikel (refereegranskat)abstract
- Immune-mediated inflammatory diseases (IMIDs) are heterogeneous and complex conditions with overlapping clinical symptoms and elevated familial aggregation, which suggests the existence of a shared genetic component. In order to identify this genetic background in a systematic fashion, we performed the first cross-disease genome-wide meta-analysis in systemic seropositive rheumatic diseases, namely, systemic sclerosis, systemic lupus erythematosus, rheumatoid arthritis and idiopathic inflammatory myopathies.MethodsWe meta-analysed ~6.5 million single nucleotide polymorphisms in 11 678 cases and 19 704 non-affected controls of European descent populations. The functional roles of the associated variants were interrogated using publicly available databases.ResultsOur analysis revealed five shared genome-wide significant independent loci that had not been previously associated with these diseases: NAB1, KPNA4-ARL14, DGQK, LIMK1 and PRR12. All of these loci are related with immune processes such as interferon and epidermal growth factor signalling, response to methotrexate, cytoskeleton dynamics and coagulation cascade. Remarkably, several of the associated loci are known key players in autoimmunity, which supports the validity of our results. All the associated variants showed significant functional enrichment in DNase hypersensitivity sites, chromatin states and histone marks in relevant immune cells, including shared expression quantitative trait loci. Additionally, our results were significantly enriched in drugs that are being tested for the treatment of the diseases under study.ConclusionsWe have identified shared new risk loci with functional value across diseases and pinpoint new potential candidate loci that could be further investigated. Our results highlight the potential of drug repositioning among related systemic seropositive rheumatic IMIDs.
|
|
| 13. |
- Bossini-Castillo, Lara, et al.
(författare)
-
A replication study confirms the association of TNFSF4 (OX40L) polymorphisms with systemic sclerosis in a large European cohort
- 2011
-
Ingår i: Annals of the Rheumatic Diseases. - : BMJ. - 1468-2060 .- 0003-4967. ; 70:4, s. 638-641
-
Tidskriftsartikel (refereegranskat)abstract
- Objectives The aim of this study was to confirm the influence of TNFSF4 polymorphisms on systemic sclerosis (SSc) susceptibility and phenotypic features. Methods A total of 8 European populations of Caucasian ancestry were included, comprising 3014 patients with SSc and 3125 healthy controls. Four genetic variants of TNFSF4 gene promoter (rs1234314, rs844644, rs844648 and rs12039904) were selected as genetic markers. Results A pooled analysis revealed the association of rs1234314 and rs12039904 polymorphisms with SSc (OR 1.15, 95% CI 1.02 to 1.31; OR 1.18, 95% CI 1.08 to 1.29, respectively). Significant association of the four tested variants with patients with limited cutaneous SSc (lcSSc) was revealed (rs1234314 OR 1.22, 95% CI 1.07 to 1.38; rs844644 OR 0.91, 95% CI 0.83 to 0.99; rs844648 OR 1.10, 95% CI 1.01 to 1.20 and rs12039904 OR 1.20, 95% CI 1.09 to 1.33). Association of rs1234314, rs844648 and rs12039904 minor alleles with patients positive for anti-centromere antibodies (ACA) remained significant (OR 1.23, 95% CI 1.10 to 1.37; OR 1.12, 95% CI 1.01 to 1.25; OR 1.22, 95% CI 1.07 to 1.38, respectively). Haplotype analysis confirmed a protective haplotype associated with SSc, lcSSc and ACA positive subgroups (OR 0.88, 95% CI 0.82 to 0.96; OR 0.88, 95% CI 0.80 to 0.96; OR 0.86, 95% CI 0.77 to 0.97, respectively) and revealed a new risk haplotype associated with the same groups of patients (OR 1.14, 95% CI 1.03 to 1.26; OR 1.20, 95% CI 1.08 to 1.35; OR 1.23, 95% CI 1.07 to 1.42, respectively). Conclusions The data confirm the influence of TNFSF4 polymorphisms in SSc genetic susceptibility, especially in subsets of patients positive for lcSSc and ACA.
|
|
| 14. |
- Fayolle, E. C., et al.
(författare)
-
Protostellar and cometary detections of organohalogens
- 2017
-
Ingår i: Nature Astronomy. - : Springer Science and Business Media LLC. - 2397-3366. ; 1:10, s. 703-708
-
Tidskriftsartikel (refereegranskat)abstract
- Organohalogens, a class of molecules that contain at least one halogen atom bonded to carbon, are abundant on the Earth where they are mainly produced through industrial and biological processes(1). Consequently, they have been proposed as biomarkers in the search for life on exoplanets(2). Simple halogen hydrides have been detected in interstellar sources and in comets, but the presence and possible incorporation of more complex halogen-containing molecules such as organohalogens into planet-forming regions is uncertain(3,4). Here we report the interstellar detection of two isotopologues of the organohalogen CH3Cl and put some constraints on CH3F in the gas surrounding the low-mass protostar IRAS 16293-2422, using the Atacama Large Millimeter/submillimeter Array (ALMA). We also find CH3Cl in the coma of comet 67P/Churyumov-Gerasimenko (67P/C-G) by using the Rosetta Orbiter Spectrometer for Ion and Neutral Analysis (ROSINA) instrument. The detections reveal an efficient pre-planetary formation pathway of organohalogens. Cometary impacts may deliver these species to young planets and should thus be included as a potential abiotical production source when interpreting future organohalogen detections in atmospheres of rocky planets.
|
|
| 15. |
- Gorlova, Olga, et al.
(författare)
-
Identification of Novel Genetic Markers Associated with Clinical Phenotypes of Systemic Sclerosis through a Genome-Wide Association Strategy
- 2011
-
Ingår i: PLoS Genetics. - : Public Library of Science (PLoS). - 1553-7404. ; 7:7
-
Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to determine, through a genome-wide association study (GWAS), the genetic components contributing to different clinical sub-phenotypes of systemic sclerosis (SSc). We considered limited (IcSSc) and diffuse (dcSSc) cutaneous involvement, and the relationships with presence of the SSc-specific auto-antibodies, anti-centromere (ACA), and anti-topoisomerase I (ATA). Four GWAS cohorts, comprising 2,296 SSc patients and 5,171 healthy controls, were meta-analyzed looking for associations in the selected subgroups. Eighteen polymorphisms were further tested in nine independent cohorts comprising an additional 3,175 SSc patients and 4,971 controls. Conditional analysis for associated SNPs in the HLA region was performed to explore their independent association in antibody subgroups. Overall analysis showed that non-HLA polymorphism rs11642873 in IRF8 gene to be associated at GWAS level with lcSSc (P = 2.32x10(-12), OR = 0.75). Also, rs12540874 in GRB10 gene (P = 1.27 x 10(-6), OR = 1.15) and rs11047102 in SOX5 gene (P = 1.39x10(-7), OR = 1.36) showed a suggestive association with lcSSc and ACA subgroups respectively. In the HLA region, we observed highly associated allelic combinations in the HLA-DQB1 locus with ACA (P = 1.79x10(-61), OR = 2.48), in the HLA-DPA1/B1 loci with ATA (P = 4.57x10(-76), OR = 8.84), and in NOTCH4 with ACA P = 8.84x10(-21), OR = 0.55) and ATA (P = 1.14x10(-8), OR = 0.54). We have identified three new non-HLA genes (IRF8, GRB10, and SOX5) associated with SSc clinical and autoantibody subgroups. Within the HLA region, HLA-DQB1, HLA-DPA1/B1, and NOTCH4 associations with SSc are likely confined to specific auto-antibodies. These data emphasize the differential genetic components of subphenotypes of SSc.
|
|
| 16. |
- Postmus, I., et al.
(författare)
-
Meta-analysis of genome-wide association studies of HDL cholesterol response to statins
- 2016
-
Ingår i: Journal of Medical Genetics. - : BMJ. - 0022-2593 .- 1468-6244. ; 53:12, s. 835-45
-
Tidskriftsartikel (refereegranskat)abstract
- Background In addition to lowering low density lipoprotein cholesterol (LDL-C), statin therapy also raises high density lipoprotein cholesterol (HDL-C) levels. Interindividual variation in HDL-C response to statins may be partially explained by genetic variation. Methods and results We performed a meta-analysis of genome-wide association studies (GWAS) to identify variants with an effect on statin-induced high density lipoprotein cholesterol (HDL-C) changes. The 123 most promising signals with p<1x10(-4) from the 16 769 statin-treated participants in the first analysis stage were followed up in an independent group of 10 951 statin-treated individuals, providing a total sample size of 27 720 individuals. The only associations of genome-wide significance (p<5x10(-8)) were between minor alleles at the CETP locus and greater HDL-C response to statin treatment. Conclusions Based on results from this study that included a relatively large sample size, we suggest that CETP may be the only detectable locus with common genetic variants that influence HDL-C response to statins substantially in individuals of European descent. Although CETP is known to be associated with HDL-C, we provide evidence that this pharmacogenetic effect is independent of its association with baseline HDL-C levels.
|
|
| 17. |
|
|
| 18. |
- Valentini, F., et al.
(författare)
-
Differential kinetic dynamics and heating of ions in the turbulent solar wind
- 2016
-
Ingår i: New Journal of Physics. - : IOP Publishing. - 1367-2630. ; 18
-
Tidskriftsartikel (refereegranskat)abstract
- The solar wind plasma is a fully ionized and turbulent gas ejected by the outer layers of the solar corona at very high speed, mainly composed by protons and electrons, with a small percentage of helium nuclei and a significantly lower abundance of heavier ions. Since particle collisions are practically negligible, the solar wind is typically not in a state of thermodynamic equilibrium. Such a complex system must be described through self-consistent and fully nonlinear models, taking into account its multi-species composition and turbulence. Weuse a kinetic hybrid Vlasov-Maxwell numerical code to reproduce the turbulent energy cascade down to ion kinetic scales, in typical conditions of the uncontaminated solar wind plasma, with the aim of exploring the differential kinetic dynamics of the dominant ion species, namely protons and alpha particles. Weshow that the response of different species to the fluctuating electromagnetic fields is different. In particular, a significant differential heating of alphas with respect to protons is observed. Interestingly, the preferential heating process occurs in spatial regions nearby the peaks of ion vorticity and where strong deviations from thermodynamic equilibrium are recovered. Moreover, by feeding a simulator of a top-hat ion spectrometer with the output of the kinetic simulations, we show that measurements by such spectrometer planned on board the Turbulence Heating ObserveR (THORmission), a candidate for the nextM4space mission of the European Space Agency, can provide detailed three-dimensional ion velocity distributions, highlighting important non-Maxwellian features. These results support the idea that future space missions will allow a deeper understanding of the physics of the interplanetary medium.
|
|
| 19. |
|
|
| 20. |
|
|
| 21. |
- Radstake, Timothy R. D. J., et al.
(författare)
-
Genome-wide association study of systemic sclerosis identifies CD247 as a new susceptibility locus
- 2010
-
Ingår i: Nature Genetics. - : Springer Science and Business Media LLC. - 1546-1718 .- 1061-4036. ; 42:5, s. 71-426
-
Tidskriftsartikel (refereegranskat)abstract
- Systemic sclerosis (SSc) is an autoimmune disease characterized by fibrosis of the skin and internal organs that leads to profound disability and premature death. To identify new SSc susceptibility loci, we conducted the first genome-wide association study in a population of European ancestry including a total of 2,296 individuals with SSc and 5,171 controls. Analysis of 279,621 autosomal SNPs followed by replication testing in an independent case-control set of European ancestry (2,753 individuals with SSc (cases) and 4,569 controls) identified a new susceptibility locus for systemic sclerosis at CD247 (1q22-23, rs2056626, P = 2.09 x 10(-7) in the discovery samples, P = 3.39 x 10(-9) in the combined analysis). Additionally, we confirm and firmly establish the role of the MHC (P = 2.31 x 10(-18)), IRF5 (P = 1.86 x 10(-13)) and STAT4 (P = 3.37 x 10(-9)) gene regions as SSc genetic risk factors.
|
|
| 22. |
- Retinò, A., et al.
(författare)
-
Particle energization in space plasmas : towards a multi-point, multi-scale plasma observatory
- 2021
-
Ingår i: Experimental astronomy. - : Springer Nature. - 0922-6435 .- 1572-9508.
-
Tidskriftsartikel (refereegranskat)abstract
- This White Paper outlines the importance of addressing the fundamental science theme “How are charged particles energized in space plasmas” through a future ESA mission. The White Paper presents five compelling science questions related to particle energization by shocks, reconnection, waves and turbulence, jets and their combinations. Answering these questions requires resolving scale coupling, nonlinearity, and nonstationarity, which cannot be done with existing multi-point observations. In situ measurements from a multi-point, multi-scale L-class Plasma Observatory consisting of at least seven spacecraft covering fluid, ion, and electron scales are needed. The Plasma Observatory will enable a paradigm shift in our comprehension of particle energization and space plasma physics in general, with a very important impact on solar and astrophysical plasmas. It will be the next logical step following Cluster, THEMIS, and MMS for the very large and active European space plasmas community. Being one of the cornerstone missions of the future ESA Voyage 2050 science programme, it would further strengthen the European scientific and technical leadership in this important field.
|
|
| 23. |
|
|
| 24. |
- Beth, A., et al.
(författare)
-
First in situ detection of the cometary ammonium ion NH4+ (protonated ammonia NH3) in the coma of 67P/C-G near perihelion
- 2016
-
Ingår i: Monthly notices of the Royal Astronomical Society. - : OXFORD UNIV PRESS. - 0035-8711 .- 1365-2966. ; 462, s. S562-S572
-
Tidskriftsartikel (refereegranskat)abstract
- In this paper, we report the first in situ detection of the ammonium ion NH4+ at 67P/Churyumov-Gerasimenko (67P/C-G) in a cometary coma, using the Rosetta Orbiter Spectrometer for Ion and Neutral Analysis (ROSINA)/Double Focusing Mass Spectrometer (DFMS). Unlike neutral and ion spectrometers onboard previous cometary missions, the ROSINA/DFMS spectrometer, when operated in ion mode, offers the capability to distinguish NH4+ from H2O+ in a cometary coma. We present here the ion data analysis of mass-to-charge ratios 18 and 19 at high spectral resolution and compare the results with an ionospheric model to put these results into context. The model confirms that the ammonium ion NH4+ is one of the most abundant ion species, as predicted, in the coma near perihelion.
|
|
| 25. |
- Goetz, C., et al.
(författare)
-
Cometary plasma science : Open science questions for future space missions
- 2021
-
Ingår i: Experimental astronomy. - : Springer Nature. - 0922-6435 .- 1572-9508.
-
Tidskriftsartikel (refereegranskat)abstract
- Comets hold the key to the understanding of our Solar System, its formation and its evolution, and to the fundamental plasma processes at work both in it and beyond it. A comet nucleus emits gas as it is heated by the sunlight. The gas forms the coma, where it is ionised, becomes a plasma, and eventually interacts with the solar wind. Besides these neutral and ionised gases, the coma also contains dust grains, released from the comet nucleus. As a cometary atmosphere develops when the comet travels through the Solar System, large-scale structures, such as the plasma boundaries, develop and disappear, while at planets such large-scale structures are only accessible in their fully grown, quasi-steady state. In situ measurements at comets enable us to learn both how such large-scale structures are formed or reformed and how small-scale processes in the plasma affect the formation and properties of these large scale structures. Furthermore, a comet goes through a wide range of parameter regimes during its life cycle, where either collisional processes, involving neutrals and charged particles, or collisionless processes are at play, and might even compete in complicated transitional regimes. Thus a comet presents a unique opportunity to study this parameter space, from an asteroid-like to a Mars- and Venus-like interaction. The Rosetta mission and previous fast flybys of comets have together made many new discoveries, but the most important breakthroughs in the understanding of cometary plasmas are yet to come. The Comet Interceptor mission will provide a sample of multi-point measurements at a comet, setting the stage for a multi-spacecraft mission to accompany a comet on its journey through the Solar System. This White Paper, submitted in response to the European Space Agency’s Voyage 2050 call, reviews the present-day knowledge of cometary plasmas, discusses the many questions that remain unanswered, and outlines a multi-spacecraft European Space Agency mission to accompany a comet that will answer these questions by combining both multi-spacecraft observations and a rendezvous mission, and at the same time advance our understanding of fundamental plasma physics and its role in planetary systems.
|
|
| 26. |
- Gorman, Jeffrey, et al.
(författare)
-
Deoxyribonucleic Acid Encoded and Size-Defined π-Stacking of Perylene Diimides
- 2022
-
Ingår i: Journal of the American Chemical Society. - : American Chemical Society (ACS). - 0002-7863 .- 1520-5126. ; 144:1, s. 368-376
-
Tidskriftsartikel (refereegranskat)abstract
- Natural photosystems use protein scaffolds to control intermolecular interactions that enable exciton flow, charge generation, and long-range charge separation. In contrast, there is limited structural control in current organic electronic devices such as OLEDs and solar cells. We report here the DNA-encoded assembly of pi-conjugated perylene diimides (PDIs) with deterministic control over the number of electronically coupled molecules. The PDIs are integrated within DNA chains using phosphoramidite coupling chemistry, allowing selection of the DNA sequence to either side, and specification of intermolecular DNA hybridization. In this way, we have developed a "toolbox" for construction of any stacking sequence of these semiconducting molecules. We have discovered that we need to use a full hierarchy of interactions: DNA guides the semiconductors into specified close proximity, hydrophobic-hydrophilic differentiation drives aggregation of the semiconductor moieties, and local geometry and electrostatic interactions define intermolecular positioning. As a result, the PDIs pack to give substantial intermolecular pi wave function overlap, leading to an evolution of singlet excited states from localized excitons in the PDI monomer to excimers with wave functions delocalized over all five PDIs in the pentamer. This is accompanied by a change in the dominant triplet forming mechanism from localized spin-orbit charge transfer mediated intersystem crossing for the monomer toward a delocalized excimer process for the pentamer. Our modular DNA-based assembly reveals real opportunities for the rapid development of bespoke semiconductor architectures with molecule-by-molecule precision.
|
|
| 27. |
- Gunell, H, et al.
(författare)
-
Acceleration of ions and nano dust at a comet in the solar wind
- 2015
-
Ingår i: Planetary and Space Science. - : Elsevier. - 0032-0633 .- 1873-5088. ; 119, s. 13-23
-
Tidskriftsartikel (refereegranskat)abstract
- A quasi-neutral hybrid simulation of the interaction of the solar wind with the atmosphere of a comet is used together with a test particle simulation of cometary ions and dust to compute trajectories and velocity distribution functions of charged particles, starting outside the diamagnetic cavity at 150 km cometocentric distance. The simulations are run with parameters suited to make predictions for comet 67P/Churyumov-Gerasimenko when it is at a heliocentric distance of 1.45 AU. It is found that the shape of the ion trajectories depends on the location of the source, and that a velocity distribution that is observed at a given point in space is influenced by the spatial structure of the source. Charged dust grains with radii in the 1-10 nm range are accelerated from the nucleus to a distance of 2.9 x 104 km in between 15 min and 2 h approximately. Dust particles smaller than 10 nm in radius are accelerated to speeds over 10 km/s.
|
|
| 28. |
- Gunell, H., et al.
(författare)
-
Ion acoustic waves at comet 67P/Churyumov-Gerasimenko : Observations and computations
- 2017
-
Ingår i: Astronomy and Astrophysics. - : EDP SCIENCES S A. - 0004-6361 .- 1432-0746. ; 600
-
Tidskriftsartikel (refereegranskat)abstract
- Context. On 20 January 2015 the Rosetta spacecraft was at a heliocentric distance of 2.5 AU, accompanying comet 67P/Churyumov-Gerasimenko on its journey toward the Sun. The Ion Composition Analyser (RPC-ICA), other instruments of the Rosetta Plasma Consortium, and the ROSINA instrument made observations relevant to the generation of plasma waves in the cometary environment.Aims. Observations of plasma waves by the Rosetta Plasma Consortium Langmuir probe (RPC-LAP) can be explained by dispersion relations calculated based on measurements of ions by the Rosetta Plasma Consortium Ion Composition Analyser (RPC-ICA), and this gives insight into the relationship between plasma phenomena and the neutral coma, which is observed by the Comet Pressure Sensor of the Rosetta Orbiter Spectrometer for Ion and Neutral Analysis instrument (ROSINA-COPS).Methods. We use the simple pole expansion technique to compute dispersion relations for waves on ion timescales based on the observed ion distribution functions. These dispersion relations are then compared to the waves that are observed. Data from the instruments RPC-LAP, RPC-ICA and the mutual impedance probe (RPC-MIP) are compared to find the best estimate of the plasma density.Results. We find that ion acoustic waves are present in the plasma at comet 67P/Churyumov-Gerasimenko, where the major ion species is H2O+. The bulk of the ion distribution is cold, k(B)T(i) = 0.01 eV when the ion acoustic waves are observed. At times when the neutral density is high, ions are heated through acceleration by the solar wind electric field and scattered in collisions with the neutrals. This process heats the ions to about 1 eV, which leads to significant damping of the ion acoustic waves.Conclusions. In conclusion, we show that ion acoustic waves appear in the H2O+ plasmas at comet 67P/Churyumov-Gerasimenko and how the interaction between the neutral and ion populations affects the wave properties.
|
|
| 29. |
- Gunell, Herbert, et al.
(författare)
-
Plasma waves confined to the diamagnetic cavity of comet 67P/Churyumov-Gerasimenko
- 2017
-
Ingår i: Monthly notices of the Royal Astronomical Society. - : Oxford University Press. - 0035-8711 .- 1365-2966. ; 469, s. S84-S92
-
Tidskriftsartikel (refereegranskat)abstract
- Ion acoustic waves were observed in the diamagnetic cavity of comet 67P/Churyumov-Gerasimenko by the Rosetta spacecraft on 2015 August 3, when the comet was 1.25 au from the Sun. Wave spectra recorded by the Langmuir probe (RPC-LAP), peak near 200 Hz, decrease for higher frequencies and reach the noise floor at approximately 1.5 kHz. These waves were observed only when the spacecraft was in the diamagnetic cavity or at its boundary, which is identified as a sharp drop in magnetic field magnitude, measured by RPC-MAG. The plasma, on both sides of the boundary, is dominated by a cold (a few hundred K) water group ion population, one cold (k(B)T(e) similar to 0.1 eV) and one warm (k(B)T(e) similar to 10 eV) electron population. The observations are interpreted in terms of current-driven ion acoustic waves, generated by currents that flow through bulges on the boundary of the diamagnetic cavity.
|
|
| 30. |
- Gunell, H., et al.
(författare)
-
Waves in high-speed plasmoids in the magnetosheath and at the magnetopause
- 2014
-
Ingår i: Annales Geophysicae. - : Copernicus GmbH. - 0992-7689 .- 1432-0576. ; 32:8, s. 991-1009
-
Tidskriftsartikel (refereegranskat)abstract
- Plasmoids, defined here as plasma entities with a higher anti-sunward velocity component than the surrounding plasma, have been observed in the magnetosheath in recent years. During the month of March 2007 the Cluster spacecraft crossed the magnetopause near the subsolar point 13 times. Plasmoids with larger velocities than the surrounding magnetosheath were found on seven of these 13 occasions. The plasmoids approach the magnetopause and interact with it. Both whistler mode waves and waves in the lower hybrid frequency range appear in these plasmoids, and the energy density of the waves inside the plasmoids is higher than the average wave energy density in the magnetosheath. When the spacecraft are in the magnetosphere, Alfvenic waves are observed. Cold ions of ionospheric origin are seen in connection with these waves, when the wave electric and magnetic fields combine with the Earth's dc magnetic field to yield an E x B/B-2 drift speed that is large enough to give the ions energies above the detection threshold.
|
|
| 31. |
- Maggiolo, R., et al.
(författare)
-
Effect of the Surface Roughness of Icy Grains on Molecular Oxygen Chemistry in Molecular Clouds
- 2019
-
Ingår i: Astrophysical Journal. - : Institute of Physics Publishing (IOPP). - 0004-637X .- 1538-4357. ; 882:2
-
Tidskriftsartikel (refereegranskat)abstract
- Molecular cloud and protosolar nebula chemistry involves a strong interaction between the gas phase and the surface of icy grains. The exchanges between the gas phase and the solid phase depend not only on the adsorption and desorption rates but also on the geometry of the surface of the grains. Indeed, for sufficient levels of surface roughness, atoms and molecules have a significant probability to collide with the grain icy mantle several times before being potentially captured. In consequence, their net sticking probability may differ from their sticking probability for a single collision with the grain surface. We estimate the effectiveness of the recapture on uneven surfaces for the various desorption processes at play in astrophysical environments. We show that surface roughness has a significant effect on the desorption rates. We focus in particular on the production of O-2 since unexpectedly large amounts of it, probably incorporated in the comet when it formed, have been detected in the coma of comet 67P by the Rosetta probe. Our results suggest that the higher escape probability of hydrogen compared to heavier species on rough surfaces can contribute to enhancing the production of O-2 in the icy mantles of grains while keeping its abundance low in the gas phase and may significantly decrease the desorption probability of molecules involved in the O-2 chemical network.
|
|
| 32. |
- Maggiolo, R., et al.
(författare)
-
The earth's magnetic field enhances solar energy deposition in the upper atmosphere
- 2022
-
Ingår i: Journal of Geophysical Research - Space Physics. - : John Wiley & Sons. - 2169-9380 .- 2169-9402. ; 127:12
-
Tidskriftsartikel (refereegranskat)abstract
- The presence of a large-scale planetary magnetic field is thought to be a protective factor for atmospheres, preventing them from being blown off by the solar wind. We focus on one key aspect of atmospheric escape: how does a planetary magnetic fields affect the energy transfer from the Sun to the atmosphere? We estimate the solar wind energy currently dissipated in the Earth's atmosphere using empirical formulas derived from observations. We show that it is significantly higher than the energy dissipated in the atmosphere of a hypothetical unmagnetized Earth. Consequently, we conclude that the Earth's magnetic field enhances the solar energy dissipation in the Earth's atmosphere and that, contrary to the old paradigm, an intrinsic magnetic field does not necessarily reduces atmospheric loss.
|
|
| 33. |
- Maggiolo, R., et al.
(författare)
-
The Effect of Cosmic Rays on Cometary Nuclei. II. Impact on Ice Composition and Structure
- 2020
-
Ingår i: Astrophysical Journal. - : IOP PUBLISHING LTD. - 0004-637X .- 1538-4357. ; 901:2
-
Tidskriftsartikel (refereegranskat)abstract
- Since their formation in the protosolar nebula some similar to 4.5 billion years ago, comets are in storage in cold distant regions of the solar system, the Kuiper Belt/scattered disk or Oort Cloud. Therefore, they have been considered as mostly unaltered samples of the protosolar nebula. However, a significant dose of energy is deposited by galactic cosmic rays (GCRs) into the outermost tens of meters of cometary nuclei during their stay in the Oort Cloud or Kuiper Belt. We investigate the impact of energy deposition by GCRs on cometary nuclei. We use experimental results from laboratory experiments and the energy deposition by GCRs estimated by Gronoff et al. (2020), to discuss the depth down to which the cometary nucleus is altered by GCRs. We show that GCRs do not significantly change the isotopic composition of cometary material but modify the chemical composition and the ice structure in the outer layers of the nucleus, which cannot be considered as pristine solar nebula material. We discuss the effect of the collisional history of comets on the distribution of processed material inside the nucleus and its implication on the observation of comets.
|
|
| 34. |
- Vaivads, Andris, et al.
(författare)
-
EIDOSCOPE : particle acceleration at plasma boundaries
- 2012
-
Ingår i: Experimental astronomy. - : Springer Science and Business Media LLC. - 0922-6435 .- 1572-9508. ; 33:2-3, s. 491-527
-
Tidskriftsartikel (refereegranskat)abstract
- We describe the mission concept of how ESA can make a major contribution to the Japanese Canadian multi-spacecraft mission SCOPE by adding one cost-effective spacecraft EIDO (Electron and Ion Dynamics Observatory), which has a comprehensive and optimized plasma payload to address the physics of particle acceleration. The combined mission EIDOSCOPE will distinguish amongst and quantify the governing processes of particle acceleration at several important plasma boundaries and their associated boundary layers: collisionless shocks, plasma jet fronts, thin current sheets and turbulent boundary layers. Particle acceleration and associated cross-scale coupling is one of the key outstanding topics to be addressed in the Plasma Universe. The very important science questions that only the combined EIDOSCOPE mission will be able to tackle are: 1) Quantitatively, what are the processes and efficiencies with which both electrons and ions are selectively injected and subsequently accelerated by collisionless shocks? 2) How does small-scale electron and ion acceleration at jet fronts due to kinetic processes couple simultaneously to large scale acceleration due to fluid (MHD) mechanisms? 3) How does multi-scale coupling govern acceleration mechanisms at electron, ion and fluid scales in thin current sheets? 4) How do particle acceleration processes inside turbulent boundary layers depend on turbulence properties at ion/electron scales? EIDO particle instruments are capable of resolving full 3D particle distribution functions in both thermal and suprathermal regimes and at high enough temporal resolution to resolve the relevant scales even in very dynamic plasma processes. The EIDO spin axis is designed to be sun-pointing, allowing EIDO to carry out the most sensitive electric field measurements ever accomplished in the outer magnetosphere. Combined with a nearby SCOPE Far Daughter satellite, EIDO will form a second pair (in addition to SCOPE Mother-Near Daughter) of closely separated satellites that provides the unique capability to measure the 3D electric field with high accuracy and sensitivity. All EIDO instrumentation are state-of-the-art technology with heritage from many recent missions. The EIDOSCOPE orbit will be close to equatorial with apogee 25-30 RE and perigee 8-10 RE. In the course of one year the orbit will cross all the major plasma boundaries in the outer magnetosphere; bow shock, magnetopause and magnetotail current sheets, jet fronts and turbulent boundary layers. EIDO offers excellent cost/benefits for ESA, as for only a fraction of an M-class mission cost ESA can become an integral part of a major multi-agency L-class level mission that addresses outstanding science questions for the benefit of the European science community.
|
|
| 35. |
- Yamauchi, M., et al.
(författare)
-
Plasma-neutral gas interactions in various space environments : Assessment beyond simplified approximations as a Voyage 2050 theme
- 2022
-
Ingår i: Experimental astronomy. - : Springer Nature. - 0922-6435 .- 1572-9508.
-
Tidskriftsartikel (refereegranskat)abstract
- In the White Paper, submitted in response to the European Space Agency (ESA) Voyage 2050 Call, we present the importance of advancing our knowledge of plasma-neutral gas interactions, and of deepening our understanding of the partially ionized environments that are ubiquitous in the upper atmospheres of planets and moons, and elsewhere in space. In future space missions, the above task requires addressing the following fundamental questions: (A) How and by how much do plasma-neutral gas interactions influence the re-distribution of externally provided energy to the composing species? (B) How and by how much do plasma-neutral gas interactions contribute toward the growth of heavy complex molecules and biomolecules? Answering these questions is an absolute prerequisite for addressing the long-standing questions of atmospheric escape, the origin of biomolecules, and their role in the evolution of planets, moons, or comets, under the influence of energy sources in the form of electromagnetic and corpuscular radiation, because low-energy ion-neutral cross-sections in space cannot be reproduced quantitatively in laboratories for conditions of satisfying, particularly, (1) low-temperatures, (2) tenuous or strong gradients or layered media, and (3) in low-gravity plasma. Measurements with a minimum core instrument package (< 15 kg) can be used to perform such investigations in many different conditions and should be included in all deep-space missions. These investigations, if specific ranges of background parameters are considered, can also be pursued for Earth, Mars, and Venus.
|
|
