| 1. |
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| 2. |
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| 3. |
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| 4. |
- Ahlberg, Erik, et al.
(author)
-
"Vi klimatforskare stödjer Greta och skolungdomarna"
- 2019
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In: Dagens nyheter (DN debatt). - 1101-2447.
-
Journal article (pop. science, debate, etc.)abstract
- DN DEBATT 15/3. Sedan industrialiseringens början har vi använt omkring fyra femtedelar av den mängd fossilt kol som får förbrännas för att vi ska klara Parisavtalet. Vi har bara en femtedel kvar och det är bråttom att kraftigt reducera utsläppen. Det har Greta Thunberg och de strejkande ungdomarna förstått. Därför stödjer vi deras krav, skriver 270 klimatforskare.
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| 5. |
- Andersson, Matts, et al.
(author)
-
A method for measuring and valuing transport time variability in logistics and cost benefit analysis
- 2017
-
In: Research in Transportation Economics. - : Elsevier. - 0739-8859 .- 1875-7979. ; 66, s. 59-69
-
Journal article (peer-reviewed)abstract
- The freight transport system is subject to delays and disturbances, which influence investment and planning decisions made by governments and infrastructure authorities. Traditionally relying on Cost Benefit Analysis (CBA) they are dependent on correct and up-to-date input data. So far, little success has been reached in estimating the effects of disturbances for freight. This paper aims to contribute to the understanding of disturbances in freight transport by reviewing and classifying the effects occurring due to transport time variability (TTV) and to suggest a calculation model to estimate the value of transport time variability (VTTV). In order to validate the model and its usability it was successfully tested in a case study for a large Swedish retail company. The effects of delays can be divided into four main types: System Killers, Catastrophic Events, Expected Risks, and Contingencies, of which the last two are relevant for VTTV. The model applies these in a two-step cost function with a fixed and variable part, building on previous studies of VTW for passenger transport based on the scheduling utility approach. A main theoretical result is that the estimation of VTTV is derived mathematically independently of which measure that is chosen for the quantification of TTV.
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| 6. |
- Andersson, Matts, et al.
(author)
-
A method for measuring and valuing transport time variability in logistics and cost benefit analysis
- 2016
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In: World Conference on Transport Research, WCTR 2016, Shanghai 10-15 July.
-
Conference paper (other academic/artistic)abstract
- Today transport system is subject to delays and disturbances, which has impacts on the transport chain itself and on the recipients of the goods. These effects influence the investment and planning decisions made by governments and infrastructure authorities. These authorities traditionally rely on Cost Benefit Analysis (CBA) as an input to their decisions. By performing CBA calculations they can base their decisions on a solid and comparable foundation. However, CBA is dependent on correct and up-to-date input data, but little success has been reached in determining the effects of disturbances. Largely, this is due to the complex and context depend nature of disturbances and thereby obvious difficulties in estimating the effects. This paper aims to contribute to the understanding of disturbances in freight transport by reviewing and classifying the effects occurring due to transport time variability (TTV) and to suggest a calculation model to mathematically estimate the value of transport time variability (VTTV). The calculation method is tested in a case study for a large Swedish retail company. An extensive literature review has been performed on the existing methods to measure TTV and VTTV. Except identifying the measures used in the studies, any discussions in the studies on which measure to use has also been analysed. Effects of delays are further analysed and mapped in an activity framework of Transport, Transhipment, Delivery, Use of goods and Overall chain effects. Based on this mapping, four main types of disturbances are identified based on Magnitude and Frequency, followed by a suggestion on how these disturbances should be managed in a VTTV perspective. A method has also been developed to mathematically estimate VTTV for freight, extending previous studies on VTTV for passenger transport based on the scheduling utility approach and linked to the previous defined framework of four main types of disturbances. The study has resulted in an improved understanding of the effects of disturbances in freight transport networks through the developed framework. Further, a mathematical method for estimating VTTV has been developed. The model contains is a two-step cost function with a fixed and variable part. The method have successfully been tested on a test data set and proven to be able to estimate VTTV. Furthermore, this study has found that the estimation of VTTV can be (and is) derived mathematically independently of which measure that is chosen for the quantification of TTV.
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| 7. |
- Bader, Alexander, et al.
(author)
-
Proton Temperature Anisotropies in the Plasma Environment of Venus
- 2019
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In: Journal of Geophysical Research - Space Physics. - : American Geophysical Union (AGU). - 2169-9380 .- 2169-9402. ; 124:5, s. 3312-3330
-
Journal article (peer-reviewed)abstract
- Velocity distribution functions (VDFs) are a key to understanding the interplay between particles and waves in a plasma. Any deviation from an isotropic Maxwellian distribution may be unstable and result in wave generation. Using data from the ion mass spectrometer IMA (Ion Mass Analyzer) and the magnetometer (MAG) onboard Venus Express, we study proton distributions in the plasma environment of Venus. We focus on the temperature anisotropy, that is, the ratio between the proton temperature perpendicular (T-perpendicular to) and parallel (T-parallel to) to the background magnetic field. We calculate average values of T-perpendicular to and T-parallel to for different spatial areas around Venus. In addition we present spatial maps of the average of the two temperatures and of their average ratio. Our results show that the proton distributions in the solar wind are quite isotropic, while at the bow shock stronger perpendicular than parallel heating makes the downstream VDFs slightly anisotropic (T-perpendicular to/T-parallel to > 1) and possibly unstable to generation of proton cyclotron waves or mirror mode waves. Both wave modes have previously been observed in Venus's magnetosheath. The perpendicular heating is strongest in the near-subsolar magnetosheath (T-perpendicular to/ T-parallel to approximate to 3/2), which is also where mirror mode waves are most frequently observed. We believe that the mirror mode waves observed here are indeed generated by the anisotropy. In the magnetotail we observe planetary protons with largely isotropic VDFs, originating from Venus's ionosphere.
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| 8. |
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| 9. |
- Bakardjieva Engelbrekt, Antonina, et al.
(author)
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EU kan fastna i negativ spiral
- 2012
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In: Svenska Dagbladet, Brännpunkt. - 1101-2412.
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Journal article (pop. science, debate, etc.)
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| 10. |
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| 11. |
- Bakardjieva Engelbrekt, Antonina, et al.
(author)
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The EU and Global Imbalances
- 2015
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In: The EU’s Role in Fighting Global Imbalances. - Cheltenham : Edward Elgar Publishing. - 9781784716721 - 9781784716738 - 978 1 78471 672 1 ; , s. 1-15
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Book chapter (peer-reviewed)
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| 12. |
- Bakardjieva Engelbrekt, Antonina, 1963-, et al.
(author)
-
The EU’s Role in Fighting Global Imbalances
- 2015
-
Book (peer-reviewed)abstract
- The EU’s Role in Fighting Global Imbalances looks at the role of the European Union in addressing some of the greatest challenges of our time: poverty, protectionism, climate change, and human trafficking. Contributions from ten leading scholars in the fields of economics, law, and political science provide in-depth analyses of three key dimensions of EU foreign policy, namely: the internal challenges facing the EU, as its 28 member countries struggle to coordinate their actions; the external challenges facing the EU on the global arena, in areas where global imbalances are particularly pervasive, and where measures taken by the Union can have an important impact; and the EU´s performance on the global arena, in the eyes of other key actors. Based on a broad and interdisciplinary understanding of the concept of global imbalances, this book argues that these challenges follow from pervasive global imbalances, which at root are economic, political, and legal in character.
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| 13. |
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| 14. |
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| 15. |
- Bernitz, Ulf, et al.
(author)
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Preface
- 2018
-
In: Bridging the Prosperity Gap in the EU : The Social Challenge Ahead - The Social Challenge Ahead. - : Edward Elgar Publishing. - 9781786436665 - 9781786436672
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Book chapter (other academic/artistic)
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| 16. |
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| 17. |
-
Bridging the Prosperity Gap in the EU : The Social Challenge Ahead
- 2018
-
Editorial collection (other academic/artistic)abstract
- Bridging the Prosperity Gap in the EU addresses the great social challenge currently facing the European Union. Taking an interdisciplinary approach, the authors invaluably pinpoint both overarching problems and possibilities associated with the social dimension of European integration. Prominent researchers of economics, law and political science tackle this complex issue, providing new solutions within their respective fields of expertise. The chapters cover crucial policy challenges and analyse fundamental mechanisms that limit, or otherwise affect, the evolution of a European social dimension. These insights clarify the far-reaching measures that will be needed to gradually restore the balance between market integration and social protection across the European Union. Illustrating the importance of cohesion, this book is vital for those interested in comparative European studies, from backgrounds in public and social policy, law and economics.
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| 18. |
-
Bridging the prosperity gap in the EU : The social challenge ahead
- 2018
-
Editorial collection (peer-reviewed)abstract
- Taking an interdisciplinary approach, the authors invaluably pinpoint both overarching problems and possibilities associated with the social dimension of European integration. Prominent researchers of economics, law and political science tackle this complex issue, providing new solutions within their respective fields of expertise. Illustrating the importance of cohesion, this book is vital for those interested in comparative European studies, from backgrounds in public and social policy, law and economics.
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| 19. |
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| 20. |
- Fowler, C. M., et al.
(author)
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Pioneer Venus Orbiter Observations of Solar Wind Driven Magnetosonic Waves Interacting With the Dayside Venusian Ionosphere
- 2024
-
In: Geophysical Research Letters. - : American Geophysical Union (AGU). - 0094-8276 .- 1944-8007. ; 51:12
-
Journal article (peer-reviewed)abstract
- We use in situ plasma observations made by the Pioneer Venus Orbiter spacecraft to show for the first time that magnetosonic waves can couple the solar wind to the upper ionosphere and deposit energy there. The waves are generated upstream of Venus, are advected into the shock and propagate across the draped magnetic field, through the magnetosheath and into the dayside upper ionosphere. The magnetosonic waves damp in the upper ionosphere in a region where physical collisions are rare, and electromagnetic forces must control this damping. The waves damp when the ionospheric heavy ion density is a few thousand cm-3 and wave-particle interactions with the dominant O+ ions are postulated as the damping mechanism. Estimates of ion heating rates show that 1%-5% of the O+ ion distribution function could be heated to escape energy in 10-40 s.
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| 21. |
- Gillmann, Cedric, et al.
(author)
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The Long-Term Evolution of the Atmosphere of Venus : Processes and Feedback Mechanisms Interior-Exterior Exchanges
- 2022
-
In: Space Science Reviews. - : Springer. - 0038-6308 .- 1572-9672. ; 218:7
-
Research review (peer-reviewed)abstract
- This work reviews the long-term evolution of the atmosphere of Venus, and modulation of its composition by interior/exterior cycling. The formation and evolution of Venus's atmosphere, leading to contemporary surface conditions, remain hotly debated topics, and involve questions that tie into many disciplines. We explore these various inter-related mechanisms which shaped the evolution of the atmosphere, starting with the volatile sources and sinks. Going from the deep interior to the top of the atmosphere, we describe volcanic outgassing, surface-atmosphere interactions, and atmosphere escape. Furthermore, we address more complex aspects of the history of Venus, including the role of Late Accretion impacts, how magnetic field generation is tied into long-term evolution, and the implications of geochemical and geodynamical feedback cycles for atmospheric evolution. We highlight plausible end-member evolutionary pathways that Venus could have followed, from accretion to its present-day state, based on modeling and observations. In a first scenario, the planet was desiccated by atmospheric escape during the magma ocean phase. In a second scenario, Venus could have harbored surface liquid water for long periods of time, until its temperate climate was destabilized and it entered a runaway greenhouse phase. In a third scenario, Venus's inefficient outgassing could have kept water inside the planet, where hydrogen was trapped in the core and the mantle was oxidized. We discuss existing evidence and future observations/missions required to refine our understanding of the planet's history and of the complex feedback cycles between the interior, surface, and atmosphere that have been operating in the past, present or future of Venus.
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| 22. |
- Julén Votinius, Jenny, et al.
(author)
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Youth, Labour Law, and European Economic Crisis
- 2018
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In: Bridging the Prosperity Gap in the EU: The Social Challenge Ahead. - : Edward Elgar Publishing. ; , s. 146-169
-
Book chapter (peer-reviewed)
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| 23. |
- Karlsson, Christer, Professor, 1965-, et al.
(author)
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Dimensions of disagreement in EU affairs : is parliamentary opposition driven by left-right or European integration contestation?
- 2024
-
In: West European Politics. - 0140-2382 .- 1743-9655.
-
Journal article (peer-reviewed)abstract
- This study provides new insights regarding how the EU dimension relates to the left-right dimension in national politics. It does so by examining to what extent parties’ oppositional behaviour in EU affairs in parliament is a function of their distance to the government, other parties, the voters and party supporters on the EU dimension and the left-right dimension, respectively. The results suggest that oppositional behaviour is determined by two parallel dynamics: When expressing opposition, political parties are receptive both to the positions of the government and other parties on the EU dimension, and to the positions of voters and supporters on the left-right dimension. Our results thus indicate that the politicization of EU affairs in national parliaments primarily is an elite phenomenon. In their relation to the voters and supporters, parties still primarily navigate along the traditional left-right dimension.
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| 24. |
- Karlsson, Christer, Professor, 1965-, et al.
(author)
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Do Members of Parliament Express More Opposition in the Plenary than in the Committee? : Comparing Frontstage and Backstage Behaviour in Five National Parliaments
- 2024
-
In: Parliamentary Affairs. - : Oxford University Press. - 0031-2290 .- 1460-2482. ; 77:1, s. 173-195
-
Journal article (peer-reviewed)abstract
- This study attempts to break new ground by systematically comparing oppositional behaviour of Members of Parliament (MPs) in the two key arenas found in parliament: the plenary and the committee. Do MPs express more opposition frontstage in the plenary than backstage in the committee when discussing European affairs? The article sheds new light on political opposition in parliament by using a dataset of hand-coded statements made by MPs during plenary debates and European Affairs committee deliberations in five national parliaments. The results lend strong support to the main hypothesis that MPs express more opposition during plenary debates than committee deliberations.
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| 25. |
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| 26. |
- Karlsson, Christer, Professor, 1965-, et al.
(author)
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Hur mycket opposition finns det i svensk EU-politik?
- 2019
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In: EU i riksdagen. - Stockholm : Svenska institutet för europapolitiska studier (Sieps). - 9789186107826 ; , s. 37-60
-
Book chapter (other academic/artistic)
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| 27. |
- Karlsson, Christer, Professor, 1965-, et al.
(author)
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Is Oppositional Behaviour in European Union Affairs Gendered? Evidence from Plenary Debates and Committee Deliberations in Four Legislatures
- 2024
-
In: Journal of Common Market Studies. - : John Wiley & Sons. - 0021-9886 .- 1468-5965. ; 62:2, s. 412-429
-
Journal article (peer-reviewed)abstract
- Is oppositional behaviour in legislatures gendered? Despite a growing literature on gender and legislative behaviour, there is a conspicuous absence of research on differences between female and male members of parliament (MPs) when it comes to one of the key aspects of parliamentary debates: the voicing of opposition. This article connects the literature on gender and legislative behaviour with opposition scholarship. We examine the role of gender for oppositional behaviour in four legislatures with a focus on debates concerning European Union affairs. Our results show that female MPs generally are equally likely to express opposition as their male colleagues. This result, however, is conditioned by government status. Whilst there is no significant difference between the proportion of opposition expressed by female and male MPs from opposition parties, we find that male MPs representing government parties express more than twice as much opposition as their female colleagues.
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| 28. |
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| 29. |
- Landergren, Magnus, 1988-, et al.
(author)
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VTTV – Value of Transport Time Variability : Method development and synthesis. Value transfer, measurements, and decomposition of VTTV
- 2015
-
Reports (peer-reviewed)abstract
- Transporttidsvinster (TTS) och minskad transporttidsvariation (TTV) för gods-och passagerartrafik är viktiga nyttoposter i de samhällsekonomiska kalkylerna inom transportsektorn. Ett av antagandena som behöver göras är den monetära värderingen av TTS och TTV – VTTS och VTTV. Resenärers värderingar av dessa mått baseras oftastpå SP-studier (Stated Preference). VTTS för godstrafik baseras på kostnaden för kapitalbindningen i, och därmed värdet av, godset. I nuläget antas VTTV vara lika med det dubbla VTTS. Transportörers nyttor av minskad transporttid och transporttidsvariation beräknas som en del av transportkostnaderna (i andra poster i kalkylen). Detta projekt fokuserar på VTTV för godstransporter.Den här rapporten består av två delar. Kapitel 2, som är skrivet av WSP, Handelshögskolan vid Göteborgs Universitet och Logistics Landscapers, beskriver WP 4 som handlar om vilket mått som ska användas för transporttidens variation, vilka delar VTTV består av samt härleder en matematisk modell för att beräkna VTTV.Syftet med WP 4 var ursprungligen att kartlägga och utvärdera olika mått för transporttidsvariationen (TTV). Med mått menas enheten som används för att kvantifiera variationen, som exempelvis standardavvikelsen eller den genomsnittliga förseningen. En litteraturstudie har genomförts där använda mått i 22 tidigare samhällsekonomiska studier i Sverige ochutomlands listas. En slutsats av litteraturstudien är att många olika mått använts, vilka kan kategoriseras underStandardavvikelseSpridning (ofta i form av skillnad mellan percentiler)Andel av sändningar som är försenadeGenomsnittlig försening (om försenad)Fördelar och nackdelar med de olika måtten diskuteras. En annan slutsats är att valet av mått sällan diskuteras i de genomgångna studierna, utan man verkar ha valt ett mått som passar undersökningsmetoden. Vidare har det undersökts om det används mått inom logistikbranschen som skulle kunna passa TTV inom samhällsekonomin. Slutsatsen är att dessa mått (eller indikatorer) är framtagna med andra syften och för användning på mikronivå (företag eller enskilda transportkedjor) vilket gör det svårt att tillämpa dem på makronivå. Dock finns ett behov av mått på en mesonivå som gör det möjligt att analysera förändringar i transportsystemet ur båda perspektiv – samhällets och enskilda aktörers.
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| 30. |
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| 31. |
- Nilsson, Hans, et al.
(author)
-
Solar cycle variation of ion escape from Mars
- 2023
-
In: Icarus. - : Academic Press. - 0019-1035 .- 1090-2643. ; 393
-
Journal article (peer-reviewed)abstract
- Using Mars Express data from 2007 until 2020 we show how ion outflow from Mars varied over more than a solar cycle, from one solar minimum to another. The data was divided into intervals with a length of one Martian year, starting from 30 April 2007 and ending 13 July 2020. The net escape rate was about 5×1024s−1 in the first covered minimum, and 2−3×1024s−1 in the most recent minimum. Ion escape peaked at 1×1025s−1 during the intervening solar maximum. The outflow is a clear function of the solar cycle, in agreement with previous studies which found a clear relationship between solar EUV flux and ion escape at Mars. The outflow during solar maximum is 2.5 to 3 times higher than in the surrounding solar minima. The average solar wind dynamic pressure over a Martian year was investigated, but does not vary much with the solar cycle. The escape rate at solar maximum is in good agreement with some recent MAVEN studies, and dominated by low energy ions at most sampled locations. A simple linear fit to the data gives a prediction of the escape rate for the much stronger solar maximum during the Phobos mission in 1989 that is consistent with observations. The fit also implies a non-linear response of ion escape for low solar EUV, with a lower initial escape response for lower solar EUV levels than those of the studied data set.
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| 32. |
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| 33. |
- Persson, Mats, et al.
(author)
-
Energy-resolved CT imaging with a photon-counting silicon-strip detector
- 2014
-
In: Medical Imaging 2014. - : SPIE - International Society for Optical Engineering. - 9780819498267 ; , s. 90333L-
-
Conference paper (peer-reviewed)abstract
- Photon-counting detectors are promising candidates for use in the next generation of x-ray CT scanners. Among the foreseen benefits are higher spatial resolution, better trade-off between noise and dose, and energy discriminating capabilities. Silicon is an attractive detector material because of its low cost, mature manufacturing process and high hole mobility. However, it is sometimes claimed to be unsuitable for use in computed tomography because of its low absorption efficiency and high fraction of Compton scatter. The purpose of this work is to demonstrate that high-quality energy-resolved CT images can nonetheless be acquired with clinically realistic exposure parameters using a photon-counting silicon-strip detector with eight energy thresholds developed in our group. We use a single detector module, consisting of a linear array of 50 0.5 × 0.4 mm detector elements, to image a phantom in a table-top lab setup. The phantom consists of a plastic cylinder with circular inserts containing water, fat and aqueous solutions of calcium, iodine and gadolinium, in different concentrations. We use basis material decomposition to obtain water, calcium, iodine and gadolinium basis images and demonstrate that these basis images can be used to separate the different materials in the inserts. We also show results showing that the detector has potential for quantitative measurements of substance concentrations.
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| 34. |
- Persson, Mats, et al.
(author)
-
Energy-resolved CT imaging with a photon-counting silicon-strip detector
- 2014
-
In: Physics in Medicine and Biology. - : IOP Publishing. - 0031-9155 .- 1361-6560. ; 59:22, s. 6709-6727
-
Journal article (peer-reviewed)abstract
- Photon-counting detectors are promising candidates for use in the next generation of x-ray computed tomography (CT) scanners. Among the foreseen benefits are higher spatial resolution, better trade-off between noise and dose and energy discriminating capabilities. Silicon is an attractive detector material because of its low cost, mature manufacturing process and high hole mobility. However, it is sometimes overlooked for CT applications because of its low absorption efficiency and high fraction of Compton scatter. The purpose of this work is to demonstrate that silicon is a feasible material for CT detectors by showing energy-resolved CT images acquired with an 80 kVp x-ray tube spectrum using a photon-counting silicon-strip detector with eight energy thresholds developed in our group. We use a single detector module, consisting of a linear array of 50 0.5 x 0.4 mm detector elements, to image a phantom in a table-top lab setup. The phantom consists of a plastic cylinder with circular inserts containing water, fat and aqueous solutions of calcium, iodine and gadolinium, in different concentrations. By using basis material decomposition we obtain water, calcium, iodine and gadolinium basis images and demonstrate that these basis images can be used to separate the different materials in the inserts. We also show results showing that the detector has potential for quantitative measurements of substance concentrations.
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| 35. |
- Persson, Moa, 1991-
(author)
-
Escape to space or return to venus : ion flows measured by venus express
- 2020
-
Doctoral thesis (other academic/artistic)abstract
- The present-day Venusian atmosphere is crushingly dense, extremely hot and arid. Yet, in its early history, Venus presumably had a massive amount of water, which, if spread evenly over the surface, provided a water depth of 10s to 100s of meters. Therefore, over the course of the atmospheric evolution, the water must have been removed from Venus. The main processes responsible for water loss can be catagorised into either diffusion into the surface materials or escape to space, where the focus of this thesis is the latter. Determining the contribution on the atmospheric evolution from each of these processes can help us understand how planetary atmospheres evolve, both here in our Solar System and in extra-solar systems, and tell us why Venus became so dry.The water escape to space is determined by several processes, where the main processes are a consequence of the interaction between the Venusian atmosphere and the solar wind. As Venus does not have an intrinsic magnetic field, its atmosphere interacts directly with the solar wind, and creates a, so called, induced magnetosphere. The interaction causes part of the solar wind energy and momentum to be transferred to the upper atmospheric particles. The additional momentum may allow the ions to reach above escape energy and escape the planet. Therefore, the interaction between the atmosphere and the solar wind is important to study to determine the rate of escape of atmospheric constituents to space.In this thesis, the escape of atmospheric constituents to space is investigated through measurements of the H+ and O+ ion flows. These ion flows were measured by the Ion Mass Analyser (IMA) on board the Venus Express spacecraft, which orbited Venus during 2006-2014. Using IMA measurements near the North Pole ionosphere, the ionospheric ion flows were shown to have a strong dusk-to-dawn component along the terminator, inside the collisional region of the atmosphere. From ion flow measurements in the magnetotail, the rate of escape of atmospheric H+ and O+ ions were shown to be affected by the solar cycle, with an average escape rate ratio near two, the stoichiometric ratio of water. The change is mainly attributed to the decrease in the net escape rates of H+, which is a result of the increase in return flows, i.e. ions that flow back towards Venus in the magnetotail. Furthermore, the O+ net escape rate increases as the amount of energy available in the upstream solar wind increases. The increase indicates, as expected, that a portion of the available energy in the upstream solar wind is transferred to the escaping ions. However, the total portion of energy transferred from the solar wind to the escaping ions decreases as the available upstream energy increases. Using the simple relation between the O+ escape rate and the upstream solar wind energy flux, the total atmospheric escape was extrapolated backwards in time, by accounting for the evolution of the solar wind parameters. The resulting total escape over the past 3.9 Ga can be translated into a global equivalent water depth of 0.02-0.6 m. This result cannot explain the massive historical water content on Venus.
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| 36. |
- Persson, Moa, 1991-, et al.
(author)
-
Global Venus-Solar wind coupling and oxygen ion escape
- 2021
-
In: Geophysical Research Letters. - : American Geophysical Union (AGU). - 0094-8276 .- 1944-8007. ; 48:4
-
Journal article (peer-reviewed)abstract
- The present‐day Venusian atmosphere is dry, yet, in its earlier history a significant amount of water evidently existed. One important water loss process comes from the energy and momentum transfer from the solar wind to the atmospheric particles. Here, we used measurements from the Ion Mass Analyzer onboard Venus Express to derive a relation between the power in the upstream solar wind and the power leaving the atmosphere through oxygen ion escape in the Venusian magnetotail. We find that on average 0.01% of the available power is transferred, and that the percentage decreases as the available energy increases. For Mars the trend is similar, but the efficiency is higher. At Earth, the ion escape does not behave similarly, as the ion escape only increases after a threshold in the available energy is reached. These results indicate that the Venusian induced magnetosphere efficiently screens the atmosphere from the solar wind.
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| 37. |
- Persson, Moa, et al.
(author)
-
H+/O+ Escape Rate Ratio in the Venus Magnetotail and its Dependence on the Solar Cycle
- 2018
-
In: Geophysical Research Letters. - : American Geophysical Union (AGU). - 0094-8276 .- 1944-8007. ; 45:20, s. 10805-10811
-
Journal article (peer-reviewed)abstract
- A fundamental question for the atmospheric evolution of Venus is how much water-related material escapes from Venus to space. In this study, we calculate the nonthermal escape of H+ and O+ ions through the Venusian magnetotail and its dependence on the solar cycle. We separate 8 years of data obtained from the ion mass analyzer on Venus Express into solar minimum and maximum. The average escape of H+ decreased from 7.6.10(24) (solar minimum) to 2.1.10(24) s(-1) (solar maximum), while a smaller decrease was found for O+: 2.9.10(24) to 2.0.10(24) s(-1). As a result, the H+/O+ flux ratio decreases from 2.6 to 1.1. This implies that the escape of hydrogen and oxygen could have been below the stoichiometric ratio of water for Venus in its early history under the more active Sun.
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| 38. |
- Persson, Moa, 1991-, et al.
(author)
-
Heavy Ion Flows in the Upper Ionosphere of the Venusian North Pole
- 2019
-
In: Journal of Geophysical Research - Space Physics. - : American Geophysical Union (AGU). - 2169-9380 .- 2169-9402. ; 124:6, s. 4597-4607
-
Journal article (peer-reviewed)abstract
- We investigate the heavy ion density and velocity in the Venusian upper ionosphere near the North Pole, using the Ion Mass Analyzer, a part of the Analyzer of Space Plasmas and Energetic Atoms 4, together with the magnetic field instruments on Venus Express. The measurements were made during June-July 2014, covering the aerobraking campaign with lowered altitude measurements (similar to 130 km). The plasma scale heights are similar to 15 km below 150-km altitude and similar to 200 km at 150-400-km altitude. A clear trend of dusk-to-dawn heavy ion flow across the polar ionosphere was found, with speeds of similar to 2-10 km/s. In addition, the flow has a significant downward radial velocity component. The flow pattern does not depend on the interplanetary magnetic field directions nor the ionospheric magnetization states. Instead, we suggest a thermal pressure gradient between the equatorial and polar terminator regions, induced by the decrease in density between the regions, as the dominant mechanism driving the ion flow. Plain Language Summary We have calculated the ion density and velocities in the Venusian polar ionosphere using measurements from the Ion Mass Analyzer on board the Venus Express spacecraft. During June-July 2014 the periapsis was lowered to similar to 130 km, which allowed for measurements down to low altitudes of the ionosphere near the North Pole. The plasma scale heights are similar to 15 km below 150-km altitude and similar to 200 km at 150-400 km, which is similar to what was found near the equatorial region by the Pioneer Venus mission. In addition, there is a clear trend of dusk-to-dawn flow, along the terminator, for the heavy ions. This is surprising, as a general flow from day-to-night is expected for the Venusian ionosphere due to the long nights and significant heating of the dayside upper atmosphere. The interplanetary magnetic field direction does not appear to affect the ion flow pattern. Instead, we propose a thermal pressure gradient as the dominant accelerating mechanism, induced by the decrease in density from the equator toward the pole.
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| 39. |
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| 40. |
- Persson, Moa, et al.
(author)
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The Venusian Atmospheric Oxygen Ion Escape : Extrapolation to the Early Solar System
- 2020
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In: Journal of Geophysical Research - Planets. - : American Geophysical Union (AGU). - 2169-9097 .- 2169-9100. ; 125:3
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Journal article (peer-reviewed)abstract
- The present atmosphere of Venus contains almost no water, but recent measurements indicate that in its early history, Venus had an Earth-like ocean. Understanding how the Venusian atmosphere evolved is important not only for Venus itself but also for understanding the evolution of other planetary atmospheres. In this study, we quantify the escape rates of oxygen ions from the present Venus to infer the past of the Venusian atmosphere. We show that an extrapolation of the current escape rates back in time leads to the total escape of 0.02-0.6 m of a global equivalent layer of water. This implies that the loss of ions to space, inferred from the present state, cannot account for the loss of an historical Earth-like ocean. We find that the O+ escape rate increases with solar wind energy flux, where more energy available leads to a higher escape rate. Oppositely, the escape rate decreases slightly with increased extreme ultraviolet radiation (EUV) flux, though the small variation of EUV flux over the measured solar cycle may explain the weak dependency. These results indicate that there is not enough energy transferred from the solar wind to Venus' upper atmosphere that can lead to the escape of the atmosphere over the past 3.9 billion years. This means that the Venusian atmosphere did not have as much water in its atmosphere as previously assumed or the present-day escape rates do not represent the historical escape rates at Venus. Otherwise, some other mechanisms have acted to more effectively remove the water from the Venusian atmosphere. Plain Language Summary Today, Venus only has small amounts of water in its atmosphere. In its early history, Venus presumably contained an Earth-like ocean of several meters. The evolution of the atmosphere may have been caused by escape of atmospheric content to space. In this study, we investigate how much the escape of oxygen ions to space could have affected the atmospheric evolution for Venus from measurements of the present-day escape rates. Using measurements of oxygen ions in the vicinity of Venus, we show that the amount of energy available in the solar wind to be transferred to the upper atmosphere of Venus determines how much of the atmosphere escapes. From the evolution of the energy in the solar wind over the past 3.9 billion years, together with the relation between the solar wind energy and oxygen ion escape, we show that in total, about 0.02-0.6 m of water depth, if spread equally over the entire Venusian surface, was lost. This indicates that either Venus did not have as much water as previously assumed or the current escape rates are not representative of the historical escape rates. Otherwise, some other mechanisms must have acted to more effectively remove the water from Venus.
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| 41. |
- Persson, Sofia, et al.
(author)
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Validation of an optimised method for quantitative detection of hepatitis E virus in pork sausage
-
Other publication (other academic/artistic)abstract
- Hepatitis E virus (HEV) is an emerging zoonosis that can be transmitted to humans through the consumption of raw or undercooked pork meat products. Several methods for detecting the virus in food have been described, but there are still few robust data on qualitative and quantitative performance characteristics. In this study, we developed an optimised workflow for quantitative detection of HEV in pork sausage based on a combination of previously existing protocols. The protocol uses sample disruption and phase separation with tri-reagent and 1-bromo-3-chloropropane, followed by RNA concentration with isopropanol precipitation. We validated the protocol for use on reverse transcription quantitative real-time PCR (RT-qPCR) and reverse transcription droplet digital (RT-ddPCR). The 95% limit of detection and limit of quantification was 200 copies/g for both RT-qPCR and RT-ddPCR. The RT-ddPCR technology has previously shown promise as a more precise alternative to RT-qPCR. However, we found no evidence for improved performance using RT-ddPCR instead of RT-qPCR in this method. Furthermore, we also evaluated different combinations of RNA concentration methods and PCR detection strategies. This showed that isopropanol precipitation of viral RNA was more than twice as efficient as magnetic silica bead-based extraction when an inhibitor tolerant RT-PCR detection strategy was used. In conclusion, we present an efficient and well-characterised method for quantitative detection of HEV in pork sausage. Such methods are valuable to provide high quality data for risk assessments and food monitoring.
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| 42. |
- Persson, Thomas, 1969-, et al.
(author)
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Drivers of parliamentary opposition in European Union politics: institutional factors or party characteristics?
- 2024
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In: Journal of European Public Policy. - : Informa UK Limited. - 1350-1763 .- 1466-4429. ; 31:3
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Journal article (peer-reviewed)abstract
- A vital political opposition is one of the cornerstones of democracy, yet we know surprisingly little about the conditions that shape it. In this paper, we offer a comprehensive assessment of the drivers of parliamentary opposition in European Union (EU) politics in five countries: Denmark; Germany; Ireland; Sweden; and the United Kingdom. Based on an extensive hand-coded data set of 7,520 statements made by members of parliament (MPs) during both plenary sessions and deliberations during European Affairs Committee (EAC) meetings, we examine how institutions and party characteristics shape two types of oppositional behaviour: the expression of critique and the presentation of alternatives. We find that both factors are important for understanding to what extent, and how, opposition is voiced in national parliaments. Oversight institutions’ strength and a party’s degree of Euroscepticism jointly function as significant determinants of the likelihood that MPs will express opposition in the form of critique. However, when it comes to the likelihood of offering alternatives, oversight institutions’ strength fails to explain variations in the share of alternatives, while degree of Euroscepticism remains a significant predictor.
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| 43. |
- Persson, Thomas, 1969-, et al.
(author)
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Eurosceptic Challenger Parties and Political Opposition in European Union Politics : Part of the Problem or Part of the Solution?
- 2019
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In: Scandinavian Political Studies. - : John Wiley & Sons. - 0080-6757 .- 1467-9477. ; 42:3-4, s. 245-269
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Journal article (peer-reviewed)abstract
- Despite extensive research on Eurosceptic challenger parties, our knowledge of their influence on political opposition has so far been sparse. In this article we make an in-depth assessment of parliamentary EU opposition, based on 4,264 statements made by national parliamentarians in the European Affairs Committees (EACs) of Denmark and Sweden. Our analysis shows that the presence of Eurosceptic challenger parties in the national parliamentary arena impacts patterns and practices of EU opposition significantly. A greater presence of ‘hard’ Eurosceptic parties in parliament is associated with more opposition in EU politics. These parties deliver a vast majority of the polity-oriented opposition towards the EU and present more policy alter- natives than mainstream parties. The findings presented have implications for our understand- ing of national parliamentary EU opposition as well as for the assessment of the impact of Eurosceptic challenger parties on the process of European integration.
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| 44. |
- Persson, Thomas, 1969-, et al.
(author)
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The influence of Eurosceptic challenger parties on mainstream party behaviour : Is oppositional behaviour contagious?
- 2023
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In: Party Politics. - : Sage Publications. - 1354-0688 .- 1460-3683. ; 29:1, s. 100-111
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Journal article (peer-reviewed)abstract
- Previous research has looked at how Eurosceptic challenger parties can cause mainstream parties to change their policy positions and bring about adjustments to their programmes. We explore whether this contagion effect extends to the parliamentary behaviour of mainstream parties in European Union (EU) affairs. The empirical analysis is based on a large-scale study of 6215 statements made by national parliamentarians in the European Affairs Committee of Sweden between 1995 and 2016. A dynamic panel analysis of the data shows that the oppositional behaviour of Eurosceptic challenger parties has a significant impact on the opposition statements made in EU affairs by mainstream parties. These findings have important implications for the general understanding of factors that drive national EU opposition.
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| 45. |
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| 46. |
- Stergiopoulou, Katerina, et al.
(author)
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Solar Orbiter Model-Data Comparison in Venus' Induced Magnetotail
- 2023
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In: Journal of Geophysical Research - Space Physics. - : American Geophysical Union (AGU). - 2169-9380 .- 2169-9402. ; 128:2
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Journal article (peer-reviewed)abstract
- We investigate the structure of the Venusian magnetotail utilizing magnetic field and electron density measurements that cover a wide range of distances from the planet, from the first two Solar Orbiter Venus flybys. We examine the magnetic field components along the spacecraft trajectory up to 80 Venus radii down the tail. Even though the magnetic field behavior differs considerably between the two cases, we see extended electron density enhancements covering distances greater than ∼20 RV in both flybys. We compare the magnetic field measurements with a global hybrid model of the induced magnetosphere and magnetotail of Venus, to examine to what degree the observations can be understood with the simulation. The model upstream conditions are stationary and the solution encloses a large volume of 83 RV × 60 RV × 60 RV in which we look for spatial magnetic field and plasma variations. We rotate the simulation solution to describe different stationary upstream IMF clock angle cases with a 10° step and find the clock angle for which the agreement between observations and model is maximized along Solar Orbiter's trajectory in 1-min steps. We find that in both flybys there is better agreement with the observations when we rotate the model for some intervals, while there are parts that cannot be well reproduced by the model irrespective of how we vary the IMF clock angle, suggesting the presence of non-stationary features in the Venus-solar wind interaction not accounted for in the hybrid model.
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| 47. |
-
The EU's Role in Fighting Global Imbalances
- 2015
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Editorial collection (peer-reviewed)abstract
- The EU’s Role in Fighting Global Imbalances looks at the role of the European Union in addressing some of the greatest challenges of our time: poverty, protectionism, climate change, and human trafficking. Contributions from ten leading scholars in the fields of economics, law, and political science provide in-depth analyses of three key dimensions of EU foreign policy, namely: the internal challenges facing the EU, as its 28 member countries struggle to coordinate their actions; the external challenges facing the EU on the global arena, in areas where global imbalances are particularly pervasive, and where measures taken by the Union can have an important impact; and the EU´s performance on the global arena, in the eyes of other key actors. Based on a broad and interdisciplinary understanding of the concept of global imbalances, this book argues that these challenges follow from pervasive global imbalances, which at root are economic, political, and legal in character.Contributions from ten leading scholars in the fields of economics, law, and political science provide in-depth analyses of three key dimensions of EU foreign policy, namely: the internal challenges facing the EU, as its 28 member countries struggle to coordinate their actions; the external challenges facing the EU on the global arena, in areas where global imbalances are particularly pervasive, and where measures taken by the Union can have an important impact; and the EU´s performance on the global arena, in the eyes of other key actors.This policy-oriented, interdisciplinary volume offers real insight into the European Union and its role in global affairs and will appeal to academics and policy-makers alike.
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| 48. |
- Way, Michael J., et al.
(author)
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Synergies Between Venus & Exoplanetary Observations : Venus and Its Extrasolar Siblings
- 2023
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In: Space Science Reviews. - : Springer Nature. - 0038-6308 .- 1572-9672. ; 219:1
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Research review (peer-reviewed)abstract
- Here we examine how our knowledge of present day Venus can inform terrestrial exoplanetary science and how exoplanetary science can inform our study of Venus. In a superficial way the contrasts in knowledge appear stark. We have been looking at Venus for millennia and studying it via telescopic observations for centuries. Spacecraft observations began with Mariner 2 in 1962 when we confirmed that Venus was a hothouse planet, rather than the tropical paradise science fiction pictured. As long as our level of exploration and understanding of Venus remains far below that of Mars, major questions will endure. On the other hand, exoplanetary science has grown leaps and bounds since the discovery of Pegasus 51b in 1995, not too long after the golden years of Venus spacecraft missions came to an end with the Magellan Mission in 1994. Multi-million to billion dollar/euro exoplanet focused spacecraft missions such as JWST, and its successors will be flown in the coming decades. At the same time, excitement about Venus exploration is blooming again with a number of confirmed and proposed missions in the coming decades from India, Russia, Japan, the European Space Agency (ESA) and the National Aeronautics and Space Administration (NASA). Here we review what is known and what we may discover tomorrow in complementary studies of Venus and its exoplanetary cousins.
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| 49. |
- Xu, Shaosui, et al.
(author)
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Statistical Mapping of Magnetic Topology at Venus
- 2023
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In: Journal of Geophysical Research - Space Physics. - : American Geophysical Union (AGU). - 2169-9380 .- 2169-9402. ; 128:12
-
Journal article (peer-reviewed)abstract
- Despite Venus having insignificant intrinsic magnetic fields, the magnetic connectivity between the solar wind and the Venus ionosphere, or magnetic topology, is not as simple as expected and is also important for characterizing the Venus space environment. This study provides a technique combining superthermal electron energy and pitch angle distributions to infer up to 6 subtypes of magnetic topology at Venus. This enables us to determine magnetic topology with automated procedures using the Venus Express (VEx) observations from May 2006 to November 2014. We find that the draped topology (both ends of a field line not connected to the collisional ionosphere) is the dominant topology in the near-Venus space environment, >70%, except at low altitudes close to the ionosphere. The open (a field line connected to both the solar wind and the collisional ionosphere) and closed (a field line connected only to the collisional ionosphere) topologies make up 20%-30% on average of the magnetotail and up to 50% at low altitudes. This study provides the first characterization of the statistical distributions of different magnetic topologies at Venus.
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| 50. |
- Yveborg, Moa, et al.
(author)
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Eliminated risk of iodine contrast cancellation with multibin spectral CT
- 2013
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In: Physics in Medicine and Biology. - : Institute of Physics (IOP). - 0031-9155 .- 1361-6560. ; 58:14, s. N201-N209
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Journal article (peer-reviewed)abstract
- This note compares the extent of contrast cancellation induced by iodinated contrast agents in energy integrating and photon counting multibin CT images. The contrast between a hypodense target and soft tissue is modeled for the two systems for a range of iodine concentrations and tube voltages. In energy integrating systems, we show that the contrast vanishes for low concentrations of iodine whereas the same effect is not seen in multibin systems. We conclude that it is the ability of multibin systems to apply weighting schemes post-acquisition that allows the operator to eliminate the risk of contrast cancellation between iodinated targets and the background.
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