| 1. |
|
|
| 2. |
- Glasbey, JC, et al.
(författare)
-
- 2021
-
swepub:Mat__t
|
|
| 3. |
- Thomas, HS, et al.
(författare)
-
- 2019
-
swepub:Mat__t
|
|
| 4. |
- Tabiri, S, et al.
(författare)
-
- 2021
-
swepub:Mat__t
|
|
| 5. |
- Bravo, L, et al.
(författare)
-
- 2021
-
swepub:Mat__t
|
|
| 6. |
|
|
| 7. |
|
|
| 8. |
|
|
| 9. |
|
|
| 10. |
- Drake, TM, et al.
(författare)
-
Surgical site infection after gastrointestinal surgery in children: an international, multicentre, prospective cohort study
- 2020
-
Ingår i: BMJ global health. - : BMJ. - 2059-7908. ; 5:12
-
Tidskriftsartikel (refereegranskat)abstract
- Surgical site infection (SSI) is one of the most common healthcare-associated infections (HAIs). However, there is a lack of data available about SSI in children worldwide, especially from low-income and middle-income countries. This study aimed to estimate the incidence of SSI in children and associations between SSI and morbidity across human development settings.MethodsA multicentre, international, prospective, validated cohort study of children aged under 16 years undergoing clean-contaminated, contaminated or dirty gastrointestinal surgery. Any hospital in the world providing paediatric surgery was eligible to contribute data between January and July 2016. The primary outcome was the incidence of SSI by 30 days. Relationships between explanatory variables and SSI were examined using multilevel logistic regression. Countries were stratified into high development, middle development and low development groups using the United Nations Human Development Index (HDI).ResultsOf 1159 children across 181 hospitals in 51 countries, 523 (45·1%) children were from high HDI, 397 (34·2%) from middle HDI and 239 (20·6%) from low HDI countries. The 30-day SSI rate was 6.3% (33/523) in high HDI, 12·8% (51/397) in middle HDI and 24·7% (59/239) in low HDI countries. SSI was associated with higher incidence of 30-day mortality, intervention, organ-space infection and other HAIs, with the highest rates seen in low HDI countries. Median length of stay in patients who had an SSI was longer (7.0 days), compared with 3.0 days in patients who did not have an SSI. Use of laparoscopy was associated with significantly lower SSI rates, even after accounting for HDI.ConclusionThe odds of SSI in children is nearly four times greater in low HDI compared with high HDI countries. Policies to reduce SSI should be prioritised as part of the wider global agenda.
|
|
| 11. |
|
|
| 12. |
- Coustenis, A., et al.
(författare)
-
TandEM : Titan and Enceladus mission
- 2009
-
Ingår i: Experimental astronomy. - : Springer Science and Business Media LLC. - 0922-6435 .- 1572-9508. ; 23:3, s. 893-946
-
Tidskriftsartikel (refereegranskat)abstract
- TandEM was proposed as an L-class (large) mission in response to ESA's Cosmic Vision 2015-2025 Call, and accepted for further studies, with the goal of exploring Titan and Enceladus. The mission concept is to perform in situ investigations of two worlds tied together by location and properties, whose remarkable natures have been partly revealed by the ongoing Cassini-Huygens mission. These bodies still hold mysteries requiring a complete exploration using a variety of vehicles and instruments. TandEM is an ambitious mission because its targets are two of the most exciting and challenging bodies in the Solar System. It is designed to build on but exceed the scientific and technological accomplishments of the Cassini-Huygens mission, exploring Titan and Enceladus in ways that are not currently possible (full close-up and in situ coverage over long periods of time). In the current mission architecture, TandEM proposes to deliver two medium-sized spacecraft to the Saturnian system. One spacecraft would be an orbiter with a large host of instruments which would perform several Enceladus flybys and deliver penetrators to its surface before going into a dedicated orbit around Titan alone, while the other spacecraft would carry the Titan in situ investigation components, i.e. a hot-air balloon (MontgolfiSre) and possibly several landing probes to be delivered through the atmosphere.
|
|
| 13. |
- Jakosky, B. M., et al.
(författare)
-
MAVEN observations of the response of Mars to an interplanetary coronal mass ejection
- 2015
-
Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 350:6261
-
Tidskriftsartikel (refereegranskat)abstract
- Coupling between the lower and upper atmosphere, combined with loss of gas from the upper atmosphere to space, likely contributed to the thin, cold, dry atmosphere of modern Mars. To help understand ongoing ion loss to space, the Mars Atmosphere and Volatile Evolution (MAVEN) spacecraft made comprehensive measurements of the Mars upper atmosphere, ionosphere, and interactions with the Sun and solar wind during an interplanetary coronal mass ejection impact in March 2015. Responses include changes in the bow shock and magnetosheath, formation of widespread diffuse aurora, and enhancement of pick-up ions. Observations and models both show an enhancement in escape rate of ions to space during the event. Ion loss during solar events early in Mars history may have been a major contributor to the long-term evolution of the Mars atmosphere.
|
|
| 14. |
|
|
| 15. |
|
|
| 16. |
- Ademuyiwa, Adesoji O., et al.
(författare)
-
Determinants of morbidity and mortality following emergency abdominal surgery in children in low-income and middle-income countries
- 2016
-
Ingår i: BMJ Global Health. - : BMJ Publishing Group Ltd. - 2059-7908. ; 1:4
-
Tidskriftsartikel (refereegranskat)abstract
- Background: Child health is a key priority on the global health agenda, yet the provision of essential and emergency surgery in children is patchy in resource-poor regions. This study was aimed to determine the mortality risk for emergency abdominal paediatric surgery in low-income countries globally.Methods: Multicentre, international, prospective, cohort study. Self-selected surgical units performing emergency abdominal surgery submitted prespecified data for consecutive children aged <16 years during a 2-week period between July and December 2014. The United Nation's Human Development Index (HDI) was used to stratify countries. The main outcome measure was 30-day postoperative mortality, analysed by multilevel logistic regression.Results: This study included 1409 patients from 253 centres in 43 countries; 282 children were under 2 years of age. Among them, 265 (18.8%) were from low-HDI, 450 (31.9%) from middle-HDI and 694 (49.3%) from high-HDI countries. The most common operations performed were appendectomy, small bowel resection, pyloromyotomy and correction of intussusception. After adjustment for patient and hospital risk factors, child mortality at 30 days was significantly higher in low-HDI (adjusted OR 7.14 (95% CI 2.52 to 20.23), p<0.001) and middle-HDI (4.42 (1.44 to 13.56), p=0.009) countries compared with high-HDI countries, translating to 40 excess deaths per 1000 procedures performed.Conclusions: Adjusted mortality in children following emergency abdominal surgery may be as high as 7 times greater in low-HDI and middle-HDI countries compared with high-HDI countries. Effective provision of emergency essential surgery should be a key priority for global child health agendas.
|
|
| 17. |
|
|
| 18. |
- Edberg, Niklas J. T., et al.
(författare)
-
Simultaneous measurements of Martian plasma boundaries by Rosetta and Mars Express
- 2009
-
Ingår i: Planetary and Space Science. - : Elsevier BV. - 0032-0633 .- 1873-5088. ; 57:8-9, s. 1085-1096
-
Tidskriftsartikel (refereegranskat)abstract
- We present the first two-spacecraft near-simultaneous observations of the Martian bow shock (BS), magnetic pileup boundary (MPB) and photo-electron boundary (PEB) obtained by the plasma instruments onboard Rosetta and Mars Express during the Rosetta Mars fly by on February 25, 2007. Our observations are compared with shape models for the BS and MPB derived from previous statistical studies. The MPB is found at its expected position but the BS for this event is found significantly closer to the planet than expected for the rather slow and moderately dense solar wind. Cross-calibration of the density measurements on the two spacecraft gives a density profile through the magnetosheath, indicating an increasing solar wind flux during the Rosetta passage which is consistent with the multiple BS crossings at the Rosetta exit.
|
|
| 19. |
- Edberg, Niklas, et al.
(författare)
-
Rosetta and Mars Express observations of the influence of high solar wind pressure on the Martian plasma environment
- 2009
-
Ingår i: Annales Geophysicae. - : Copernicus GmbH. - 0992-7689 .- 1432-0576. ; 27:12, s. 4533-4545
-
Tidskriftsartikel (refereegranskat)abstract
- We report on new simultaneous in-situ observations at Mars from Rosetta and Mars Express (MEX) on how the Martian plasma environment is affected by high pressure solar wind. A significant sharp increase in solar wind density, magnetic field strength and turbulence followed by a gradual increase in solar wind velocity is observed during similar to 24 h in the combined data set from both spacecraft after Rosetta's closest approach to Mars on 25 February 2007. The bow shock and magnetic pileup boundary are coincidently observed by MEX to become asymmetric in their shapes. The fortunate orbit of MEX at this time allows a study of the inbound boundary crossings on one side of the planet and the outbound crossings on almost the opposite side, both very close to the terminator plane. The solar wind and interplanetary magnetic field (IMF) downstream of Mars are monitored through simultaneous measurements provided by Rosetta. Possible explanations for the asymmetries are discussed, such as crustal magnetic fields and IMF direction. In the same interval, during the high solar wind pressure pulse, MEX observations show an increased amount of escaping planetary ions from the polar region of Mars. We link the high pressure solar wind with the observed simultaneous ion outflow and discuss how the pressure pulse could also be associated with the observed boundary shape asymmetry.
|
|
| 20. |
|
|
| 21. |
|
|
| 22. |
|
|
| 23. |
- Brain, D., et al.
(författare)
-
A comparison of global models for the solar wind interaction with Mars
- 2010
-
Ingår i: Icarus. - : Elsevier BV. - 0019-1035 .- 1090-2643. ; 206:1, s. 139-151
-
Tidskriftsartikel (refereegranskat)abstract
- We present initial results from the first community-wide effort to compare global plasma interaction model results for Mars. Seven modeling groups participated in this activity, using MHD, multi-fluid, and hybrid assumptions in their simulations. Moderate solar wind and solar EUV conditions were chosen, and the conditions were implemented in the models and run to steady state. Model output was compared in three ways to determine how pressure was partitioned and conserved in each model, the location and asymmetry of plasma boundaries and pathways for planetary ion escape, and the total escape flux of planetary oxygen ions. The two participating MHD models provided similar results, while the five sets of multi-fluid and hybrid results were different in many ways. All hybrid results, however, showed two main channels for oxygen ion escape (a pickup ion 'plume' in the hemisphere toward which the solar wind convection electric field is directed, and a channel in the opposite hemisphere of the central magnetotail), while the MHD models showed one (a roughly symmetric channel in the central magnetotail). Most models showed a transition from an upstream region dominated by plasma dynamic pressure to a magnetosheath region dominated by thermal pressure to a low altitude region dominated by magnetic pressure. However, calculated escape rates for a single ion species varied by roughly an order of magnitude for similar input conditions, suggesting that the uncertainties in both the current and integrated escape over martian history as determined by models are large. These uncertainties are in addition to those associated with the evolution of the Sun, the martian dynamo, and the early atmosphere, highlighting the challenges we face in constructing Mars' past using models.
|
|
| 24. |
- Hadid, L. Z., et al.
(författare)
-
Ambipolar electrostatic field in negatively charged dusty plasma
- 2022
-
Ingår i: Journal of Plasma Physics. - : Cambridge University Press. - 0022-3778 .- 1469-7807. ; 88:2
-
Tidskriftsartikel (refereegranskat)abstract
- We study the effect of negatively charged dust on the magnetic-field-aligned polarisation electrostatic field (E-parallel to) using Cassini's RPWS/LP in situ measurements during the `ring-grazing' orbits. We derive a general expression for E-parallel to and estimate for the first time in situ parallel to E-parallel to parallel to (approximately 10(-5) V m(-1)) near the Janus and Epimetheus rings. We further demonstrate that the presence of the negatively charged dust close to the ring plane (vertical bar Z vertical bar less than or similar to 0.11 R-s) amplifies parallel to E-parallel to parallel to by at least one order of magnitude and reverses its direction due to the effect of the charged dust gravitational and inertial forces. Such reversal confines the electrons at the magnetic equator within the dusty region, around 0.047 R-s above the ring plane. Furthermore, we discuss the role of the collision terms, in particular the ion-dust drag force, in amplifying E-parallel to. These results imply that the charged dust, as small as nanometres in size, can have a significant influence on the plasma transport, in particular ambipolar diffusion along the magnetic field lines, and so their presence must be taken into account when studying such dynamical processes.
|
|
| 25. |
- Bertucci, C., et al.
(författare)
-
The magnetic memory of Titan's ionized atmosphere
- 2008
-
Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 321:5895, s. 1475-1478
-
Tidskriftsartikel (refereegranskat)abstract
- After 3 years and 31 close flybys of Titan by the Cassini Orbiter, Titan was finally observed in the shocked solar wind, outside of Saturn's magnetosphere. These observations revealed that Titan's flow- induced magnetosphere was populated by "fossil" fields originating from Saturn, to which the satellite was exposed before its excursion through the magnetopause. In addition, strong magnetic shear observed at the edge of Titan's induced magnetosphere suggests that reconnection may have been involved in the replacement of the fossil fields by the interplanetary magnetic field.
|
|
| 26. |
- Garnier, P., et al.
(författare)
-
Titan's ionosphere in the magnetosheath : Cassini RPWS results during the T32 flyby
- 2009
-
Ingår i: Annales Geophysicae. - : Copernicus GmbH. - 0992-7689 .- 1432-0576. ; 27:11, s. 4257-4272
-
Tidskriftsartikel (refereegranskat)abstract
- The Cassini mission has provided much information about the Titan environment, with numerous low altitude encounters with the moon being always inside the magnetosphere. The only encounter taking place outside the magnetopause, in the magnetosheath, occurred the 13 June 2007 (T32 flyby). This paper is dedicated to the analysis of the Radio and Plasma Wave investigation data during this specific encounter, in particular with the Langmuir probe, providing a detailed picture of the cold plasma environment and of Titan's ionosphere with these unique plasma conditions. The various pressure terms were also calculated during the flyby. The comparison with the T30 flyby, whose geometry was very similar to the T32 encounter but where Titan was immersed in the kronian magnetosphere, reveals that the evolution of the incident plasma has a significant influence on the structure of the ionosphere, with in particular a change of the exo-ionospheric shape. The electrical conductivities are given along the trajectory of the spacecraft and the discovery of a polar plasma cavity is reported.
|
|
| 27. |
- Kim, Won Keun, et al.
(författare)
-
Outcomes and performance of the ACURATE neo2 transcatheter heart valve in clinical practice : one-yearresults of the ACURATE neo2 PMCF Study
- 2024
-
Ingår i: EuroIntervention : journal of EuroPCR in collaboration with the Working Group on Interventional Cardiology of the European Society of Cardiology. - 1969-6213. ; 20:1, s. 85-94
-
Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Transcatheter aortic valve implantation is an effective treatment for patients with aortic stenosis; however, complications related to paravalvular leakage (PVL) persist, including increased risk of mortality, cardiovascular mortality, and rehospitalisation. AIMS: We sought to evaluate the clinical outcomes and valve performance at 1 year in patients with severe aortic stenosis treated with the ACURATE neo2 valve in a post-market clinical setting. METHODS: Valve Academic Research Consortium-2 safety events were assessed up to 1 year. Independent core laboratories evaluated echocardiographic measures of valve performance and hypoattenuated leaflet thickening (HALT; as measured by four-dimensional computed tomography). RESULTS: The study enrolled 250 patients (64% female; mean age: 81 years; baseline Society of Thoracic Surgeons risk score: 2.9±2.0%); 246 patients were implanted with ACURATE neo2. All-cause mortality was 0.8% at 30 days and 5.1% at 1 year. The 1-year rates for stroke and disabling stroke were 3.0% and 1.3%, respectively. Overall, HALT of >50% leaflet involvement of at least one leaflet was present in 9% of patients at 30 days and in 12% of patients at 1 year. No association was observed between the presence of HALT and 1-year clinical or haemodynamic outcomes. Early haemodynamic improvements were maintained up to 1 year (mean aortic valve gradient: 47.6±14.5 mmHg at baseline, 7.6±3.2 mmHg at 1 year; mean aortic valve area: 0.7±0.2 cm2 at baseline, 1.7±0.4 cm2 at 1 year). At 1 year, 99% of patients had mild or no/trace PVL (<1% had moderate PVL; no patient had severe PVL). CONCLUSIONS: The study outcomes confirm favourable performance and safety up to 1 year in patients treated with ACURATE neo2 in routine clinical practice. (ClinicalTrials.gov: NCT04655248).
|
|
| 28. |
- Madic, C., et al.
(författare)
-
Futuristic back-end of the nuclear fuel cycle with the partitioning of minor actinides
- 2007
-
Ingår i: Journal of Alloys and Compounds. - 0925-8388. ; 444, s. 23-27
-
Tidskriftsartikel (refereegranskat)abstract
- For future back-end of the nuclear fuel cycle, the partitioning of minor actinides: Np, Am and Cm, followed by their transmutation will minimize importantly the radiotoxicity of nuclear glass waste. In this paper, the research done in France and in Europe will be presented: (i) partitioning of Np by modified PUREX process, (ii) partitioning of Am and Cm by the DIAMEX and SANEX hydrometallurgical processes. (c) 2007 Published by Elsevier B.V.
|
|
| 29. |
|
|
| 30. |
- Morooka, Michiko, et al.
(författare)
-
The electron density of Saturn's magnetosphere
- 2009
-
Ingår i: Annales Geophysicae. - : Copernicus GmbH. - 0992-7689 .- 1432-0576. ; 27:7, s. 2971-2991
-
Tidskriftsartikel (refereegranskat)abstract
- We have investigated statistically the electron density below 5 cm(-3) in the magnetosphere of Saturn (7-80 R-S, Saturn radii) using 44 orbits of the floating potential data from the RPWS Langmuir probe (LP) onboard Cassini. The density distribution shows a clear dependence on the distance from the Saturnian rotation axis (root X-2 + Y-2) as well as on the distance from the equatorial plane (vertical bar Z vertical bar), indicating a disc-like structure. From the characteristics of the density distribution, we have identified three regions: the extension of the plasma disc, the magnetodisc region, and the lobe regions. The plasma disc region is at L<15, where L is the radial distance to the equatorial crossing of the dipole magnetic field line, and confined to vertical bar Z vertical bar <5 R-S. The magnetodisc is located beyond L=15, and its density has a large variability. The variability has quasi-periodic characteristics with a periodicity corresponding to the planetary rotation. For Z > 15 R-S, the magnetospheric density distribution becomes constant in Z. However, the density still varies quasi-periodically with the planetary rotation also in this region. In fact, the quasi-periodic variation has been observed all over the magnetosphere beyond L=15. The region above Z=15 R-S is identified as the lobe region. We also found that the magnetosphere can occasionally move latitudinally under the control of the density in the magnetosphere and the solar wind. From the empirical distributions of the electron densities obtained in this study, we have constructed an electron density model of the Saturnian nightside magnetosphere beyond 7 R-S. The obtained model can well reproduce the observed density distribution, and can thus be useful for magnetospheric modelling studies.
|
|
| 31. |
|
|
| 32. |
- Retegan Vollmer, Teodora, 1979, et al.
(författare)
-
Synthesis and Screening of t-Bu-CyMe4-BTBP, and Comparison with CyMe4-BTBP
- 2014
-
Ingår i: Solvent Extraction and Ion Exchange. - : Informa UK Limited. - 0736-6299 .- 1532-2262. ; 32:7, s. 720-736
-
Tidskriftsartikel (refereegranskat)abstract
- The effect of adding a t-butyl group to the core molecule of CyMe4-BTBP, with the aim of improving solubility in organic diluents, has been studied with regard to the extraction of Am(III) and Eu(III) from HNO3. Synthesis of t-Bu-CyMe4-BTBP is described in detail. Metal nitrates are extracted from nitric acid in the form of 1:2 complexes, M(NO3)(3)(BTBP)(2). Whether in 1-octanol, kerosene, or cyclohexanone diluents, t-Bu-CyMe4-BTBP extracts with larger distribution ratios but with slower kinetics than CyMe4-BTBP. The general trends previously observed for CyMe4-BTBP regarding the diluent and modifier influence were also found for t-Bu-CyMe4-BTBP.
|
|
| 33. |
- Wei, H. Y., et al.
(författare)
-
Cold ionospheric plasma in Titan's magnetotail
- 2007
-
Ingår i: Geophysical Research Letters. - 0094-8276 .- 1944-8007. ; 34:24, s. L24S06-
-
Tidskriftsartikel (refereegranskat)abstract
- The interaction between Titan and the corotating Saturnian plasma forms an induced magnetosphere with an elongated Alfven-wing-style magnetotail. On 26 December 2005, the Cassini spacecraft flew through Titan's magnetotail, providing the first distant tail observation, over 5 Titan radii downstream. We examine measurements observed by the magnetometer and Langmuir probe during this pass. We use the direction of the magnetic field along the trajectory to identify the source regions of plasma reaching the spacecraft. Cold plasma, with a density of about 10 cm(-3), is found magnetically connected to the ionosphere. Titan's ionosphere appears to be escaping along field lines down the tail, leading to particle loss from the atmosphere.
|
|
| 34. |
- Bourg, S., et al.
(författare)
-
ACSEPT-Partitioning technologies and actinide science: Towards pilot facilities in Europe
- 2011
-
Ingår i: Nuclear Engineering and Design. - : Elsevier BV. - 0029-5493. ; 241:9, s. 3427-3435
-
Tidskriftsartikel (refereegranskat)abstract
- Actinide recycling by separation and transmutation is considered worldwide and particularly in several European countries as one of the most promising strategies to reduce the inventory of radioactive waste and to optimise the use of natural resources. With its multidisciplinary consortium of 34 partners from 12 European countries plus Australia and Japan, the European Research Project ACSEPT (Actinide recycling by SEParation and Transmutation) aims at contributing to the development of this strategy by studying both hydrometallurgical and pyrochemical partitioning routes. ACSEPT is organised into three technical domains: (i) Considering technically mature aqueous separation processes, ACSEPT works to optimise and select the most promising ones dedicated either to actinide partitioning (for the heterogeneous recycling of actinides in ADS target or specific actinide bearing blanket fuels in fast reactor) or to grouped actinide separation (for the homogeneous recycling of the actinides in fast reactor fuels). In addition, dissolution and conversion studies are underway taking into account the specific requirements of these specific fuels. (ii) Concerning pyrochemical separation processes. ACSEPT focuses on the enhancement of the two reference cores processes selected within FP6-EUROPART. R&D efforts are also devoted to key scientific and technical issues compulsory to set up a complete separation process (head-end steps, salt treatment for recycling and waste management). (iii) By integrating all the experimental results in engineering and system studies, both in hydro and pyro domains, ACSEPT will deliver relevant flowsheets and recommendations to prepare for future demonstrations at a pilot level. After more than two years of work, significant progress was achieved in process development with the demonstration of the SANEX and innovative SANEX flowsheets. Chemical systems were selected for GANEX and are under study. In addition, efforts were made to increase collaborations, mutualise and homogenise procedures and share good practices. Based on these assessments, it is now time to look at the future challenges to overcome. A training and education program is implemented to share the knowledge among the partitioning community, present and future generations of researchers. Specific attention is paid to the funding of post-doctorate fellowships, two having been appointed respectively at the end of 2008 and at the end of 2009. Through this training and education programme, the first ACSEPT International Workshop was organised last March in Lisbon, Portugal. It gave an emphasis to young researchers' contributions (two thirds of the contributions) and allowed young scientists to meet and exchange with international recognised experts.
|
|
| 35. |
- Edberg, Niklas, et al.
(författare)
-
Electron density and temperature measurements in the cold plasma environment of Titan : Implications for atmospheric escape
- 2010
-
Ingår i: Geophysical Research Letters. - 0094-8276 .- 1944-8007. ; 37:20, s. L20105-
-
Tidskriftsartikel (refereegranskat)abstract
- We present electron temperature and density measurements of Titan's cold ionospheric plasma from the Langmuir probe instrument on Cassini from 52 flybys. An expression of the density as a function of temperature is presented for altitudes below two Titan radii. The density falls off exponentially with increased temperature as log(n(e)) = -2.0log(T-e) + 0.6 on average around Titan. We show that this relation varies with location around Titan as well as with the solar illumination direction. Significant heating of the electrons appears to take place on the night/wake side of Titan as the density-temperature relation is less steep there. Furthermore, we show that the magnetospheric ram pressure is not balanced by the thermal and magnetic pressure in the topside ionosphere and discuss its implications for plasma escape. The cold ionospheric plasma of Titan extends to higher altitudes in the wake region, indicating the loss of atmosphere down the induced magnetospheric tail.
|
|
| 36. |
- Edberg, Niklas J. T., et al.
(författare)
-
Extreme densities in Titan's ionosphere during the T85 magnetosheath encounter
- 2013
-
Ingår i: Geophysical Research Letters. - : American Geophysical Union (AGU). - 0094-8276 .- 1944-8007. ; 40:12, s. 2879-2883
-
Tidskriftsartikel (refereegranskat)abstract
- We present Cassini Langmuir probe measurements of the highest electron number densities ever reported from the ionosphere of Titan. The measured density reached 4310cm(-3) during the T85 Titan flyby. This is at least 500cm(-3) higher than ever observed before and at least 50% above the average density for similar solar zenith angles. The peak of the ionospheric density is not reached on this flyby, making the maximum measured density a lower limit. During this flyby, we also report that an impacting coronal mass ejection (CME) leaves Titan in the magnetosheath of Saturn, where it is exposed to shocked solar wind plasma for at least 2 h 45 min. We suggest that the solar wind plasma in the magnetosheath during the CME conditions significantly modifies Titan's ionosphere by an addition of particle impact ionization by precipitating protons.
|
|
| 37. |
- Hill, C., et al.
(författare)
-
Assessment of ligand extraction properties: an intercomparison campaign amongst EUROPARTners
- 2008
-
Ingår i: Radiochimica Acta. - : Walter de Gruyter GmbH. - 0033-8230 .- 2193-3405. ; 96:4-5, s. 259-264
-
Tidskriftsartikel (refereegranskat)abstract
- An intercomparison campaign was organized at the beginning of the European FP6 EUROPART Integrated Project, among the partners involved in the assessment of the extracting properties of novel ligands, in order to check their accuracy and reliability when determining metal cation distribution ratios. Three different extracting systems, presenting various selectivity and affinity towards trivalent actinides were selected: (i) CMPO, (ii) TPTZ and (iii) BTP. Although some differences could be pointed out in the implementation of liquid-liquid extraction tests, the distribution ratios measured by the nine partners were fairly reproducible (
|
|
| 38. |
- Leblanc, F., et al.
(författare)
-
Ganymede's atmosphere as constrained by HST/STIS observations
- 2023
-
Ingår i: Icarus. - : Elsevier BV. - 0019-1035 .- 1090-2643. ; 399
-
Tidskriftsartikel (refereegranskat)abstract
- A new analysis of aurora observations of Ganymede's atmosphere on the orbital leading and trailing hemispheres has been recently published by Roth et al. (2021), suggesting that water is its main constituent near noon. Here, we present two additional aurora observations of Ganymede's sub-Jovian and anti-Jovian hemispheres, which suggest a modulation of the atmospheric H2O/O-2 ratio on the moon's orbital period, and analyze the orbital evolution of the atmosphere. For this, we propose a reconstruction of aurora observations based on a physical modelling of the exosphere taking into account its orbital variability (the Exospheric Global Model; Leblanc et al., 2017). The solution described in this paper agrees with Roth et al. (2021) that Ganymede's exosphere should be dominantly composed of water molecules. From Ganymede's position when its leading hemisphere is illuminated to when it is its trailing hemisphere, the column density of O-2 may vary between 4.3 x 10(14) and 3.6 x 10(14) cm(-2) whereas the H2O column density should vary between 5.6 x 10(14) and 1.3 x 10(15) cm(-2). The water content of Ganymede's atmosphere is essentially constrained by its sublimation rate whereas the O-2 component of Ganymede's atmosphere is controlled by the radiolytic yield. The other species, products of the water molecules, vary in a more complex way depending on their sources, either as ejecta from the surface and/or as product of the dissociation of the other atmospheric constituents. Electron impact on H2O and H-2 molecules is shown to likely produce H Lyman-alpha emissions close to Ganymede, in addition to the observed extended Lyman-alpha corona from H resonant scattering. All these conclusions being highly dependent on our capability to accurately model the origins of the observed Ganymede auroral emissions, modelling these emissions remains poorly constrained without an accurate knowledge of the Jovian magnetospheric and Ganymede ionospheric electron populations.
|
|
| 39. |
- Modolo, Ronan, et al.
(författare)
-
A global hybrid model for Titan's interaction with the Kronian plasma : Application to the Cassini Ta flyby
- 2008
-
Ingår i: Journal of Geophysical Research. - 0148-0227 .- 2156-2202. ; 113:A1, s. A01317-
-
Tidskriftsartikel (refereegranskat)abstract
- The interaction between the corotating magnetospheric plasma of Saturn and the exosphere of Titan is investigated by means of a three-dimensional and multispecies hybrid simulation model coupling charged and neutral species via three ionizing mechanisms: the absorption of extreme ultraviolet solar photons, the impacts of magnetospheric electrons, and the charge exchange reactions between ions and neutral atoms or molecules. The simulation model includes the low and energetic components of the magnetospheric plasma, the main exospheric neutral species (molecular hydrogen and nitrogen and methane), and the atmospheric slowing down of charged particles penetrating below the exobase. Ionization rates of the exospheric species are computed as consistently as possible for each of the three ionizing mechanisms by making use of the relevant local number densities and cross sections or ionization frequencies. This model is thus able to provide a priori estimates of the escaping fluxes of exospheric ionic species and to separate for the contributions of the different ionization sources. A simulation run has been made for the conditions encountered by spacecraft Cassini during flyby Ta of Titan on 26 October 2004. Results are presented to characterize the main features of the simulated plasma environment of Titan: the induced magnetic tail and the flow of magnetospheric plasma around Titan, as well as the wake and the acceleration of the planetary plasma. Considering the coarse spatial resolution of the present simulation, these features are in reasonable agreement with in situ plasma measurements made by spacecraft Cassini.
|
|
| 40. |
- Modolo, Ronan, et al.
(författare)
-
Plasma environment in the wake of Titan from hybrid simulation : A case study
- 2007
-
Ingår i: Geophysical Research Letters. - 0094-8276 .- 1944-8007. ; 34:24, s. L24S07-
-
Tidskriftsartikel (refereegranskat)abstract
- On 26 December 2005, the Cassini spacecraft flew through Titan's plasma wake and revealed a complex and dynamic region. Observations suggest a strong asymmetry which seems to be displaced from the ideal position of the wake. Two distinct plasma regions are identified with a significant difference on the electron number density and on the plasma composition. Simulation results using a three-dimensional and multi-species hybrid model, performed in conditions similar to those encountered during the flyby, are presented and compared to the observations. An acceptable agreement is shown between the model predictions and the observations. We suggest that the observed asymmetries, in terms of density and plasma composition, are mainly caused by the a combination of the asymmetry in the ion/electron production rate and the magnetic field morphology, where the first plasma region is connected to the dayside hemisphere of Titan's ionosphere while the other is connected to the nightside hemisphere.
|
|
| 41. |
- Mold, Jeff E., et al.
(författare)
-
Divergent clonal differentiation trajectories establish CD8(+) memory T cell heterogeneity during acute viral infections in humans
- 2021
-
Ingår i: Cell Reports. - : Elsevier BV. - 2211-1247. ; 35:8
-
Tidskriftsartikel (refereegranskat)abstract
- The CD8(+) T cell response to an antigen is composed of many T cell clones with unique T cell receptors, together forming a heterogeneous repertoire of effector and memory cells. How individual T cell clones contribute to this heterogeneity throughout immune responses remains largely unknown. In this study, we longitudinally track human CD8(+) T cell clones expanding in response to yellow fever virus (YFV) vaccination at the single-cell level. We observed a drop in clonal diversity in blood from the acute to memory phase, suggesting that clonal selection shapes the circulating memory repertoire. Clones in the memory phase display biased differentiation trajectories along a gradient from stem cell to terminally differentiated effector memory fates. In secondary responses, YFV- and influenza-specific CD8(+) T cell clones are poised to recapitulate skewed differentiation trajectories. Collectively, we show that the sum of distinct clonal phenotypes results in the multifaceted human T cell response to acute viral infections.
|
|
| 42. |
- Romanelli, N., et al.
(författare)
-
Outflow and plasma acceleration in Titan's induced magnetotail : Evidence of magnetic tension forces
- 2014
-
Ingår i: Journal of Geophysical Research - Space Physics. - 2169-9380 .- 2169-9402. ; 119:12
-
Tidskriftsartikel (refereegranskat)abstract
- Cassini plasma wave and particle observations are combined with magnetometer measurements to study Titan's induced magnetic tail. In this study, we report and analyze the plasma acceleration in Titan's induced magnetotail observed in flybys T17, T19, and T40. Radio and Plasma Wave Science observations show regions of cold plasma with electron densities between 0.1 and a few tens of electrons per cubic centimeter. The Cassini Plasma Spectrometer (CAPS)-ion mass spectrometer (IMS) measurements suggest that ionospheric plasma in this region is composed of ions with masses ranging from 15 to 17 amu and from 28 to 31 amu. From these measurements, we determine the bulk velocity of the plasma and the Alfven velocity in Titan's tail region. Finally, a Walen test of such measurements suggest that the progressive acceleration of the ionospheric plasma shown by CAPS can be interpreted in terms of magnetic tension forces.
|
|
| 43. |
- Schmidt, H., et al.
(författare)
-
Gamma and pulsed electron radiolysis studies of CyMe 4 BTBP and CyMe 4 BTPhen: Identification of radiolysis products and effects on the hydrometallurgical separation of trivalent actinides and lanthanides
- 2021
-
Ingår i: Radiation Physics and Chemistry. - : Elsevier BV. - 1879-0895 .- 0969-806X. ; 189
-
Tidskriftsartikel (refereegranskat)abstract
- The radiolytic stability of the highly selective ligands CyMe4BTBP and CyMe4BTPhen against ionizing gamma radiation was studied in 1-octanol solution. CyMe4BTBP and CyMe4BTPhen are important extractants for a potential treatment of used nuclear fuel. They were studied under identical experimental conditions to directly compare the effects of gamma and pulsed electron radiolysis on the ligands and systematically study the influence of structural changes in the ligand backbone. Distribution ratios of Am3+, Cm3+ and Eu3+, the residual concentration of CyMe4BTBP and CyMe4BTPhen in solution, and the formation of radiolysis products were studied as a function of absorbed gamma dose and presence of an acidic aqueous phase during irradiation. Quantitative and semi-quantitative analyses were used to elucidate the radiolysis mechanism for both ligands. Addition products of alpha-hydroxyoctyl radicals formed through radiolysis of the 1-octanol diluent to the ligand molecules were identified as the predominant radiolysis products. These addition products also extract trivalent metal ions, as distribution ratios remained high although the parent molecule concentrations decreased. Therefore, the utilization time of a solvent using these extractants under the harsh conditions of used nuclear fuel treatment could be considerably longer than expected. Understanding the radiolysis mechanism is crucial for designing more radiation resistant extractants.
|
|
| 44. |
- Schmidt, H., et al.
(författare)
-
Gamma radiolysis of the highly selective ligands CyMe4BTBP and CyMe(4)BTPhen: Qualitative and quantitative investigation of radiolysis products
- 2016
-
Ingår i: Atalante 2016 International Conference on Nuclear Chemistry for Sustainable Fuel Cycles. - : Elsevier BV. - 1876-6196. ; 21, s. 32-37
-
Konferensbidrag (refereegranskat)abstract
- The highly selective nitrogen donor ligands CyMe4BTBP and CyMe(4)BTPhen where gamma-irradiated under identical experimental conditions in 1-octanol with and without contact to nitric acid solution. Subsequently, solvent extraction experiments were carried out to evaluate the stability of the extractants against gamma-radiation monitoring Am(III) and Eu(III) distribution ratios. Generally, decreasing distribution ratios with increasing absorbed dose were detected for both molecules. Furthermore, qualitative mass spectrometric analyses were performed and ligand concentrations were determined by HPLC-DAD after irradiation to investigate the radiolysis mechanism. An exponential decrease with increasing absorbed dose was observed for both ligands with a faster rate for CyMe(4)BTPhen. Main radiolysis products indicated the addition of one or more diluent molecules (1-octanol) to the ligand via prior production of a-hydroxyoctyl radicals from diluent radiolysis. The addition of nitric acid during the irradiation lead to a remarkable stabilization of the system, as the extraction of Am(III) and Eu(III) did not change significantly over the whole examined dose range. Quantification of the remaining ligand concentration on the other hand showed decreasing concentrations with increasing absorbed dose. The stabilization of D values is therefore explained by the formation of 1-octanol addition products which are also able to extract the studied metal ions.
|
|
| 45. |
- Wilden, A., et al.
(författare)
-
Gamma-Radiolytic Stability of Solvents Containing C5-BPP (2,6-Bis(5-(2,2-dimethylpropyl)-1H-pyrazol-3-yl)pyridine) for Actinide(III)/Lanthanide(III) Separation
- 2016
-
Ingår i: Solvent Extraction and Ion Exchange. - : Informa UK Limited. - 0736-6299 .- 1532-2262. ; 34:1, s. 1-12
-
Tidskriftsartikel (refereegranskat)abstract
- The stability of solvents containing the C5-BPP (2,6-Bis(5-(2,2-dimethylpropyl)-1H-pyrazol-3-yl)pyridine) extractant against gamma-irradiation up to 330 kGy adsorbed dose was evaluated using HPLC mass spectrometric and solvent extraction methods. The main radiolysis products were identified using high-resolution mass spectrometry. Quantitative analysis of the residual C5-BPP concentration in irradiated samples was accomplished by a specifically developed MRM (Multiple Reaction Monitoring) method. A mixture of C5-BPP with 2-bromohexanoic acid in kerosene and 1-octanol, which had been used in an actinide(III)/lanthanide(III) separation process demonstration test, was also studied for its radiolytic stability and a remarkable protective effect of the presence of nitric acid during irradiation was found.
|
|
| 46. |
- Ågren, Karin, et al.
(författare)
-
Detection of currents and associated electric fields in Titan's ionosphere from Cassini data
- 2011
-
Ingår i: Journal of Geophysical Research. - 0148-0227 .- 2156-2202. ; 116:4, s. A04313-
-
Tidskriftsartikel (refereegranskat)abstract
- We present observations from three Cassini flybys of Titan using data from the radio and plasma wave science, magnetometer and plasma spectrometer instruments. We combine magnetic field and cold plasma measurements with calculated conductivities and conclude that there are currents of the order of 10 to 100 nA m (2) flowing in the ionosphere of Titan. The currents below the exobase (similar to 1400 km) are principally field parallel and Hall in nature, while the Pedersen current is negligible in comparison. Associated with the currents are perpendicular electric fields ranging from 0.5 to 3 mu V m (1).
|
|
| 47. |
- Ågren, Karin, et al.
(författare)
-
On magnetospheric electron impact ionisation and dynamics in Titan's ram-side and polar ionosphere - a Cassini case study
- 2007
-
Ingår i: Annales Geophysicae. - 0992-7689 .- 1432-0576. ; 25:11, s. 2359-2369
-
Tidskriftsartikel (refereegranskat)abstract
- We present data from the sixth Cassini flyby of Titan (T5), showing that the magnetosphere of Saturn strongly interacts with the moon's ionosphere and exo-ionosphere. A simple electron ionisation model provides a reasonable agreement with the altitude structure of the ionosphere. Furthermore, we suggest that the dense and cold exo-ionosphere (from the exobase at 1430 km and outward to several Titan radii from the surface) can be explained by magnetospheric forcing and other transport processes whereas exospheric ionisation by impacting low energy electrons seems to play a minor role.
|
|
| 48. |
- Ågren, Karin, et al.
(författare)
-
On the ionospheric structure of Titan
- 2009
-
Ingår i: Planetary and Space Science. - : Elsevier BV. - 0032-0633 .- 1873-5088. ; 57:14-15, s. 1821-1827
-
Tidskriftsartikel (refereegranskat)abstract
- In this study we present data from 17 Titan flybys showing that solar photons are the main ionisation source of Titan's dayside atmosphere. This is the first comprehensive study of Solar Zenith Angle (SZA) dependence of the electron number density and electron temperature at the ionospheric peak. The results show on average four times more plasma on the dayside compared to the nightside, with typical dayside electron densities of around 2500-3500 cm(-3) and corresponding nightside densities of around 400-1000 cm(-3). We identify a broad transition region between SZA 50 degrees and 100 degrees, where the ionosphere of Titan changes from being entirely sunlit to being in the shadow of the moon. For SZA <50 degrees the ionisation peak altitude increases with increasing SZA, whereas the transition region and the nightside show more scattered ionospheric peak altitudes. Typical electron temperatures at the ionospheric peak are 0.03-0.06 eV (approximate to 350-700 K) for both dayside and nightside. (C) 2009 Elsevier Ltd. All rights reserved.
|
|
