| 1. |
- Feroci, M., et al.
(författare)
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The large observatory for x-ray timing
- 2014
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Ingår i: Proceedings of SPIE - The International Society for Optical Engineering. - : SPIE. - 9780819496126
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Konferensbidrag (refereegranskat)abstract
- The Large Observatory For x-ray Timing (LOFT) was studied within ESA M3 Cosmic Vision framework and participated in the final downselection for a launch slot in 2022-2024. Thanks to the unprecedented combination of effective area and spectral resolution of its main instrument, LOFT will study the behaviour of matter under extreme conditions, such as the strong gravitational field in the innermost regions of accretion flows close to black holes and neutron stars, and the supranuclear densities in the interior of neutron stars. The science payload is based on a Large Area Detector (LAD, 10 m2 effective area, 2-30 keV, 240 eV spectral resolution, 1° collimated field of view) and a Wide Field Monitor (WFM, 2-50 keV, 4 steradian field of view, 1 arcmin source location accuracy, 300 eV spectral resolution). The WFM is equipped with an on-board system for bright events (e.g. GRB) localization. The trigger time and position of these events are broadcast to the ground within 30 s from discovery. In this paper we present the status of the mission at the end of its Phase A study.
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| 2. |
- Tuskan, G A, et al.
(författare)
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The genome of black cottonwood, Populus trichocarpa (Torr. & Gray).
- 2006
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Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 1095-9203 .- 0036-8075. ; 313:5793, s. 1596-604
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Tidskriftsartikel (refereegranskat)abstract
- We report the draft genome of the black cottonwood tree, Populus trichocarpa. Integration of shotgun sequence assembly with genetic mapping enabled chromosome-scale reconstruction of the genome. More than 45,000 putative protein-coding genes were identified. Analysis of the assembled genome revealed a whole-genome duplication event; about 8000 pairs of duplicated genes from that event survived in the Populus genome. A second, older duplication event is indistinguishably coincident with the divergence of the Populus and Arabidopsis lineages. Nucleotide substitution, tandem gene duplication, and gross chromosomal rearrangement appear to proceed substantially more slowly in Populus than in Arabidopsis. Populus has more protein-coding genes than Arabidopsis, ranging on average from 1.4 to 1.6 putative Populus homologs for each Arabidopsis gene. However, the relative frequency of protein domains in the two genomes is similar. Overrepresented exceptions in Populus include genes associated with lignocellulosic wall biosynthesis, meristem development, disease resistance, and metabolite transport.
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| 3. |
- Berthomier, M., et al.
(författare)
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Alfven : magnetosphere-ionosphere connection explorers
- 2012
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Ingår i: Experimental astronomy. - Dordrecht : Springer. - 0922-6435 .- 1572-9508. ; 33:2-3, s. 445-489
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Tidskriftsartikel (refereegranskat)abstract
- The aurorae are dynamic, luminous displays that grace the night skies of Earth's high latitude regions. The solar wind emanating from the Sun is their ultimate energy source, but the chain of plasma physical processes leading to auroral displays is complex. The special conditions at the interface between the solar wind-driven magnetosphere and the ionospheric environment at the top of Earth's atmosphere play a central role. In this Auroral Acceleration Region (AAR) persistent electric fields directed along the magnetic field accelerate magnetospheric electrons to the high energies needed to excite luminosity when they hit the atmosphere. The "ideal magnetohydrodynamics" description of space plasmas which is useful in much of the magnetosphere cannot be used to understand the AAR. The AAR has been studied by a small number of single spacecraft missions which revealed an environment rich in wave-particle interactions, plasma turbulence, and nonlinear acceleration processes, acting on a variety of spatio-temporal scales. The pioneering 4-spacecraft Cluster magnetospheric research mission is now fortuitously visiting the AAR, but its particle instruments are too slow to allow resolve many of the key plasma physics phenomena. The Alfv,n concept is designed specifically to take the next step in studying the aurora, by making the crucial high-time resolution, multi-scale measurements in the AAR, needed to address the key science questions of auroral plasma physics. The new knowledge that the mission will produce will find application in studies of the Sun, the processes that accelerate the solar wind and that produce aurora on other planets.
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| 4. |
- Hilson, P., et al.
(författare)
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Versatile gene-specific sequence tags for Arabidopsis functional genomics : Trancript profiling and reverse genetics applications
- 2004
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Ingår i: Genome Research. - : Cold Spring Harbor Laboratory. - 1088-9051 .- 1549-5469. ; 14:10B, s. 2176-2189
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Tidskriftsartikel (refereegranskat)abstract
- Microarray transcript profiling and RNA interference are two new technologies crucial for large-scale gene function studies in multicellular eukaryotes. Both rely on sequence-specific hybridization between complementary nucleic acid strands, inciting us to create a collection of gene-specific sequence tags (GSTs) representing at least 21,500 Arabidopsis genes and which are compatible with both approaches. The GSTs were carefully selected to ensure that each of them shared no significant similarity with any other region in the Arabidopsis genome. They were synthesized by PCR amplification from genomic DNA. Spotted microarrays fabricated from the GSTs show good dynamic range, specificity, and sensitivity in transcript profiling experiments. The GSTs have also been transferred to bacterial plasmid vectors via recombinational cloning protocols. These cloned GSTs constitute the ideal starting point for a variety of functional approaches, including reverse genetics. We have subcloned GSTs on a large scale into vectors designed for gene silencing in plant cells. We show that in planta expression of GST hairpin RNA results in the expected phenotypes in silenced Arabidopsis lines. These versatile GST resources provide novel and powerful tools for functional genomics.
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| 5. |
- Johansson, R., et al.
(författare)
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A strategy for assessing safe use of sensors in autonomous road vehicles
- 2017
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Ingår i: 36th International Conference on Computer Safety, Reliability, and Security, SAFECOMP 2017. - Cham : Springer. - 9783319662657 ; , s. 149-161
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Konferensbidrag (refereegranskat)abstract
- When arguing safety for an autonomous road vehicle it is considered very hard to show that the sensing capability is sufficient for all possible scenarios that might occur. Already for today’s manually driven road vehicles equipped with advanced driver assistance systems (ADAS), it is far from trivial how to argue that the sensor systems are sufficiently capable of enabling a safe behavior. In this paper, we argue that the transition from ADAS to automated driving systems (ADS) enables new solution patterns for the safety argumentation dependent on the sensor systems. A key factor is that the ADS itself can compensate for a lower sensor capability, by for example lowering the speed or increasing the distances. The proposed design strategy allocates safety requirements on the sensors to determine their own capability. This capability is then to be balanced by the tactical decisions of the ADS equipped road vehicle.
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| 6. |
- Teixeira, André, et al.
(författare)
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Cyber security analysis of state estimators in electric power systems
- 2010
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Ingår i: 49TH IEEE CONFERENCE ON DECISION AND CONTROL (CDC). ; , s. 5991-5998
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Konferensbidrag (refereegranskat)abstract
- In this paper, we analyze the cyber security of state estimators in Supervisory Control and Data Acquisition (SCADA) systems operating in power grids. Safe and reliable operation of these critical infrastructure systems is a major concern in our society. In current state estimation algorithms there are bad data detection (BDD) schemes to detect random outliers in the measurement data. Such schemes are based on high measurement redundancy. Although such methods may detect a set of very basic cyber attacks, they may fail in the presence of a more intelligent attacker. We explore the latter by considering scenarios where deception attacks are performed, sending false information to the control center. Similar attacks have been studied before for linear state estimators, assuming the attacker has perfect model knowledge. Here we instead assume the attacker only possesses a perturbed model. Such a model may correspond to a partial model of the true system, or even an out-dated model. We characterize the attacker by a set of objectives, and propose policies to synthesize stealthy deceptions attacks, both in the case of linear and nonlinear estimators. We show that the more accurate model the attacker has access to, the larger deception attack he can perform undetected. Specifically, we quantify trade-offs between model accuracy and possible attack impact for different BDD schemes. The developed tools can be used to further strengthen and protect the critical state-estimation component in SCADA systems.
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| 7. |
- Aspeborg, Henrik, et al.
(författare)
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Carbohydrate-active enzymes involved in the secondary cell wall biogenesis in hybrid aspen
- 2005
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Ingår i: Plant Physiology. - : Oxford University Press (OUP). - 0032-0889 .- 1532-2548. ; 137:3, s. 983-997
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Tidskriftsartikel (refereegranskat)abstract
- Wood formation is a fundamental biological process with significant economic interest. While lignin biosynthesis is currently relatively well understood, the pathways leading to the synthesis of the key structural carbohydrates in wood fibers remain obscure. We have used a functional genomics approach to identify enzymes involved in carbohydrate biosynthesis and remodeling during xylem development in the hybrid aspen Populus tremula x tremuloides. Microarrays containing cDNA clones from different tissue-specific libraries were hybridized with probes obtained from narrow tissue sections prepared by cryosectioning of the developing xylem. Bioinformatic analyses using the sensitive tools developed for carbohydrate-active enzymes allowed the identification of 25 xylem-specific glycosyltransferases belonging to the Carbohydrate-Active EnZYme families GT2, GT8, GT14, GT31, GT43, GT47, and GT61 and nine glycosidases (or transglycosidases) belonging to the Carbohydrate-Active EnZYme families GH9, GH10, GH16, GH17, GH19, GH28, GH35, and GH51. While no genes encoding either polysaccharide lyases or carbohydrate esterases were found among the secondary wall-specific genes, one putative O-acetyltransferase was identified. These wood-specific enzyme genes constitute a valuable resource for future development of engineered fibers with improved performance in different applications.
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| 8. |
- Bonagas, Nadilly, et al.
(författare)
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Pharmacological targeting of MTHFD2 suppresses acute myeloid leukemia by inducing thymidine depletion and replication stress
- 2022
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Ingår i: NATURE CANCER. - : Springer Science and Business Media LLC. - 2662-1347. ; 3:2, s. 156-
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Tidskriftsartikel (refereegranskat)abstract
- The folate metabolism enzyme MTHFD2 (methylenetetrahydrofolate dehydrogenase/cyclohydrolase) is consistently overexpressed in cancer but its roles are not fully characterized, and current candidate inhibitors have limited potency for clinical development. In the present study, we demonstrate a role for MTHFD2 in DNA replication and genomic stability in cancer cells, and perform a drug screen to identify potent and selective nanomolar MTHFD2 inhibitors; protein cocrystal structures demonstrated binding to the active site of MTHFD2 and target engagement. MTHFD2 inhibitors reduced replication fork speed and induced replication stress followed by S-phase arrest and apoptosis of acute myeloid leukemia cells in vitro and in vivo, with a therapeutic window spanning four orders of magnitude compared with nontumorigenic cells. Mechanistically, MTHFD2 inhibitors prevented thymidine production leading to misincorporation of uracil into DNA and replication stress. Overall, these results demonstrate a functional link between MTHFD2-dependent cancer metabolism and replication stress that can be exploited therapeutically with this new class of inhibitors. Helleday and colleagues describe a nanomolar MTHFD2 inhibitor that causes replication stress and DNA damage accumulation in cancer cells via thymidine depletion, demonstrating a potential therapeutic strategy in AML tumors in vivo.
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| 9. |
- Buccolieri, R., et al.
(författare)
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Flow and pollutant dispersion within the canal grande channel in venice (Italy) via CFD techniques
- 2010
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Ingår i: HARMO 2010 - Proceedings of the 13th International Conference on Harmonisation within Atmospheric Dispersion Modelling for Regulatory Purposes. ; , s. 760-764
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Konferensbidrag (refereegranskat)abstract
- The present paper is aimed at the analysis of flow and pollutant dispersion in a portion of the Canal Grande (Grand Canal) in Venice (Italy) by means of both Computational Fluid Dynamics (CFD) FLUENT simulations and wind tunnel experiments performed at the University of Gävle (Sweden). For this application, Canal Grande can be viewed as a sort of street canyon where the bottom surface is water and bus boat emissions are the major source of pollution. Numerical investigations were made to assess the effect of the water surface on air flow and pollutant concentrations in the atmosphere. One of the challenges has been to deal with the interface between two immiscible fluids which requires ad-hoc treatment of the wall in terms of the numerical scheme adopted and the grid definition which needs to be much finer than in typical numerical airflow simulations in urban street canyons. Preliminary results have shown that the presence of water at the bottom of the street canyon modifies airflow and turbulence structure with direct consequences on concentration distribution within the domain.
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| 10. |
- Cole, S. G., et al.
(författare)
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Arctic games : An analytical framework for identifying options for sustainable natural resource governance
- 2016
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Ingår i: The Polar Journal. - : Taylor and Francis Ltd.. - 2154-896X .- 2154-8978. ; 6:1
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Tidskriftsartikel (refereegranskat)abstract
- Changes in the Arctic are fuelled by a variety of drivers, including global warming, economic growth, improved access to natural resources, technological advances and globalisation processes. Further, the region is characterised by a diverse set of international agreements, national legislations and common pool resources. This presents challenges for actors to suggest, evaluate and agree on sustainable development alternatives. We propose an analytical framework to better understand (1) the types of trade-offs associated with Arctic futures and (2) actors’ incentives for strategic behaviour. In the framework, game theory illuminates incentives and strategies among actors, cost-benefit analysis and economic valuation of ecosystem services help identify socially desirable outcomes and institutional analysis provides insight on how governance structures can support or interfere with policy intervention. We apply the proposed framework by analysing possible oil development futures for Lofoten in Northern Norway. For example, institutional analysis and estimates of costs and benefits of reducing oil spill risk and their distribution among actors are used for discussing incentive structures, including the use of side payments as a mechanism to mitigate conflicting interests.
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