| 1. |
- Andersson, Anders, et al.
(författare)
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A transcriptional timetable of autumn senescence
- 2004
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Ingår i: Genome Biology. - : Springer Science and Business Media LLC. - 1465-6906 .- 1474-760X. ; 5:4, s. R24-
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Tidskriftsartikel (refereegranskat)abstract
- Background We have developed genomic tools to allow the genus Populus (aspens and cottonwoods) to be exploited as a full-featured model for investigating fundamental aspects of tree biology. We have undertaken large-scale expressed sequence tag (EST) sequencing programs and created Populus microarrays with significant gene coverage. One of the important aspects of plant biology that cannot be studied in annual plants is the gene activity involved in the induction of autumn leaf senescence. Results On the basis of 36,354 Populus ESTs, obtained from seven cDNA libraries, we have created a DNA microarray consisting of 13,490 clones, spotted in duplicate. Of these clones, 12,376 (92%) were confirmed by resequencing and all sequences were annotated and functionally classified. Here we have used the microarray to study transcript abundance in leaves of a free-growing aspen tree (Populus tremula) in northern Sweden during natural autumn senescence. Of the 13,490 spotted clones, 3,792 represented genes with significant expression in all leaf samples from the seven studied dates. Conclusions We observed a major shift in gene expression, coinciding with massive chlorophyll degradation, that reflected a shift from photosynthetic competence to energy generation by mitochondrial respiration, oxidation of fatty acids and nutrient mobilization. Autumn senescence had much in common with senescence in annual plants; for example many proteases were induced. We also found evidence for increased transcriptional activity before the appearance of visible signs of senescence, presumably preparing the leaf for degradation of its components.
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| 2. |
- Andersson, Andreas
(författare)
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Democracy and UN-interventions : A study of state commitment to UN-interventions 1991-1999
- 2002
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- After the Cold War a new world-order is in the making. The 1990s prove to be a seminal decade for sketching the contours of the emerging order. This developing order indicates a change in the legitimate use of force. As civil wars erupted world-wide, the international community managed these conflicts by an unparalleled use of UN-interventions, the most legitimate type of intervention. Where to allocate these interventions and which states decide to do so are argued to have long-term implications for the legitimate use of force. Detecting a pattern of these events suggests what to expect of the future use of force, and how to understand it. Over the past two decades the research known as the Democratic Peace Proposition (DPP) has shown that democracy affects the use of force (e.g. war) between states. Capitalising on these findings, this study centres on the three questions of how democratic norms affect states' commitment to UN-interventions, armed conflicts receiving a UN-intervention and the relationship between committing states and armed conflicts.The thesis uses unique data on states' monthly participation to all UN-interventions in the 1990s, to analyse the relationship between state commitment and democracy. The findings suggest tendencies, together indicating a significant development in our understanding of when multilateral use of force is to be expected. The democratic states' preference to intervene in lesser democratic states is very likely to affect the incidence of UN-interventions.
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| 3. |
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| 4. |
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| 5. |
- Andersson, Andreas, et al.
(författare)
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The impact of demography on the real exchange rate
- 2001
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Theory predicts that life cycle saving mechanisms will cause real exchange rate variations as the age structure varies. We investigate the impact of demography on the Swedish real exchange rate, measured as the real TCW index, during 1960 to 2000. Time series regressions show that the Swedish demographic structure has significant explanatory power on the real exchange rate. A model using age shares alone as regressors is used for medium term out-of-sample forecasts, outperforming both a naive forecast and forecasts based on an autoregressive model. Finally we use the estimated model in order to make forecasts of the Swedish real exchange rate up to 2015. The model predicts that the Swedish age structure will have a depreciating effect on the real exchange rate up to 2007 followed by an appreciating effect in the end of the forecasting period.
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| 6. |
- Andersson, Björn, et al.
(författare)
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Raloxifene does not affect insulin sensitivity or glycemic control in postmenopausal women with type 2 diabetes mellitus: a randomized clinical trial.
- 2002
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Ingår i: The Journal of clinical endocrinology and metabolism. - : The Endocrine Society. - 0021-972X .- 1945-7197. ; 87:1, s. 122-8
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Tidskriftsartikel (refereegranskat)abstract
- Little is known about the metabolic or cardiovascular effects of selective ER modulators (SERMs), such as raloxifene hydrochloride (RLX), in postmenopausal women with type 2 diabetes mellitus (DM). Therefore, the effect of RLX vs. placebo (PL) on glycemic control, insulin sensitivity, as well as effects on a number of hormone, lipid, coagulation, and safety factors were determined in 30 postmenopausal women with type 2 DM in a randomized, double blind, cross-over trial. All participants had a SHBG serum concentration below 60 nmol/liter at baseline and had stable diabetes controlled by either oral hypoglycemic agents or diet for 1 month. In the first treatment period, participants received 12 wk of either PL or RLX, followed by an 8-wk washout before the second treatment period. In the second treatment period, participants were crossed over to the other treatment. Compared with PL, RLX did not significantly affect fasting blood glucose, hemoglobin A(1c), lipids, fasting insulin, or insulin sensitivity (as measured by the euglycemic clamp technique). Compared with PL, RLX reduced fibrinogen levels by 0.77 g/liter (P < 0.001), IGF-I by 2.4 nmol/liter (P < 0.001), and free T by 0.73 pmol/liter (P = 0.038) and increased SHBG by 5.5 nmol/liter (P = 0.001) and IGF-binding protein-3 by 0.57 ng/ml (P = 0.007). Our results demonstrate that RLX does not significantly affect glycemic control and has favorable or neutral effects on selected surrogate markers of cardiovascular risk in postmenopausal women with type 2 diabetes mellitus while decreasing hyperandrogenicity in these patients.
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| 7. |
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| 8. |
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| 9. |
- Andersson, Dan, et al.
(författare)
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Managing Risk When Outsourcing Advanced Logistics
- 2003
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Ingår i: ; , s. 377-391
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Konferensbidrag (refereegranskat)abstract
- The paper describes and analyses both shipper’s and provider’s risk in outsourcing advanced logistics services. Also the risk management process (including risk analysis, risk assessment and risk management) of both companies are described and discussed. Conclusions are that risk management have been of increasing importance both during and after the outsourcing decision, and that both parties have developed their risk management processes and contingency plans due to the changed risk situation. Contracts play a vital role in risk management; but liability is an issue where there is a gap between the parties as well as in theory.
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| 10. |
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| 11. |
- Andersson, Dan, 1966-, et al.
(författare)
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Outsourcing Advanced Logistics : A Shipper's and Provider's Perspective on Risks
- 2004
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Ingår i: Supply Chain Risk. - Aldershot : Ashgate Publishing Ltd. - 0754639029 - 9780754639022 ; , s. 160-174
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- This collection, written by international scholars from the UK, US and Scandinavia, provides empirical case studies within services and manufacturing in both large and SME organizations. The findings represent a robust cross-disciplinary view of supply chains, articulating policies and strategies for organizations. This work provides the foundation for future research in this expanding area and the impact it has on managing risk within the supply chain
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| 12. |
- Andersson, Dan, et al.
(författare)
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Procurement of logistics services a minutes work or a multi-year project?
- 2002
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Ingår i: European Journal of Purchasing & Supply Management. - 0969-7012 .- 1873-6858. ; 8:1
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Tidskriftsartikel (refereegranskat)abstract
- The purpose of the article is to describe and compare the purchasing process for advanced versus basic logistics services. Further some specific observations are presented from the procurement of advanced third-party logistics services, with respect to service definitions, providers evaluations and contracts. The purchasing process of logistics services will in the future need to be more differentiated due to current business trends. Hence companies must analyse how these new procurement situations will impact on their purchasing processes in order to understand what new resources, routines and competence they need to have in order to purchase logistics services in an effective way. © 2002 Published by Elsevier Science Ltd.
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| 13. |
- Andersson, Dan, 1966-, et al.
(författare)
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Risk Management in Outsourced Logistics
- 2004
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Ingår i: Annual NOFOMA Conference for Nordic Researchers in Logistics: Challenging Boundaries with Logistics.,2004. - Linköping : Linköpings universitet. ; , s. 35-, s. 35-51
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Konferensbidrag (refereegranskat)
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| 14. |
- Andersson, Emma, et al.
(författare)
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Antimicrobial activities of heparin-binding peptides.
- 2004
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Ingår i: European Journal of Biochemistry. - : Wiley. - 0014-2956. ; 271:6, s. 1219-1226
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Tidskriftsartikel (refereegranskat)abstract
- Antimicrobial peptides are effector molecules of the innate immune system. We recently showed that the human antimicrobial peptides alpha-defensin and LL-37 bind to glycosaminoglycans (heparin and dermatan sulphate). Here we demonstrate the obverse, i.e. structural motifs associated with heparin affinity (cationicity, amphipaticity, and consensus regions) may confer antimicrobial properties to a given peptide. Thus, heparin-binding peptides derived from laminin isoforms, von Willebrand factor, vitronectin, protein C inhibitor, and fibronectin, exerted antimicrobial activities against Gram-positive and Gram-negative bacteria. Similar results were obtained using heparin-binding peptides derived from complement factor C3 as well as consensus sequences for heparin-binding (Cardin and Weintraub motifs). These sequence motifs, and additional peptides, also killed the fungus Candida albicans. These data will have implications for the search for novel antimicrobial peptides and utilization of heparin-protein interactions should be helpful in the identification and purification of novel antimicrobial peptides from complex biological mixtures. Finally, consensus regions may serve as templates for de novo synthesis of novel antimicrobial molecules.
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| 15. |
- Andersson, Jan, et al.
(författare)
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Utslagen fiskrekrytering och sviktande fiskbestånd i Kalmar läns kustvatten
- 2000
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Undersökningar gjorda 1994-1997 i ett antal områden i Kalmarsund visade minskande bestånd av främst gädda och abborre samt en låg årsyngelproduktion vid jämförelse med tidigare studier. Observationerna stöddes av rapporter från fiskare och allmänhet och uppfattades så allvarliga, att ett tvåårigt forskningsprojekt beslutades genomföras för att dels dokumentera skadornas karaktär och geografiska utbredning, dels analyserade bakomliggande orsakerna. Projektet, som pågick under 1998-1999, omfattade ett flertal områden efter Kalmarsunds fastlandskust, ett område öster om Öland, samt några referensområden norr om sundet och ett söder därom. Inventerande provfisken och årsyngelundersökningar gjordes för att kartlägga fisksamhällets sammansättning och rekryteringen till de vuxna bestånden. Trålningar genomfördes under abborrens kläckningsperiod för att mäta tätheten av fisklarver samt undersöka deras överlevnad och tillväxt. I samband med detta gjordes insamlingar av djurplankton för att kartlägga larvernas födounderlag. Fält- och laboratorieexperiment genomfördes för att studera romutveckling, kläckning och larvöverlevnad hos gädda och abborre. Som stöd vid tolkningarna av resultaten inhämtades vattenkemiska data från den samordnade kustvattenkontrollen i Kalmar län.Tätheten av främst vuxen abborre men även gädda var mycket låg i området mellan Emån och Revsudden i sundets mitt och andelen gamla fiskar var stor. Även längre ner mot länsgränsen fanns tecken på att bestånden var negativt påverkade. På lokalen vid östra Öland var tätheterna likaså mycket låga. Inventeringen av årsyngel gav en ännu mer negativ bild. Bara ett fåtal yngel av abborre och gädda fångades i hela Kalmarsundsområdet. Även yngel av karpfiskar,strömming och stubbar förekom i lågatätheter. Något påverkade alltså fiskrekryteringen så negativt, att även de vuxna bestånden av flertalet arter reducerats. Det strandnära yngel- och småfisksamhället dominerades av spiggar, vilka förekom i högre tätheter än i referensområdena. Resultaten från de lokaler som besökts vid upprepade tillfällen visade att skadorna förvärrats med tiden.Vattenkemiska data visade, att högsalt- eller ammoniumhalt knappast kunde vara en tänkbar förklaring till den uteblivna rekryteringen. Ammoniumhalterna når inte skadliga nivåer i rekryteringsområdena, och salthalten har minskat i stället för ökat i kustområdet under de senaste 10 åren. Såväl fält- som laboratorieexperimenten gav resultat som talar emot en toxisk påverkan på föräldrafiskar eller ägg och larver. Befruktningsgrad, kläckning och larvöverlevnad vartill synes normala. Undersökning av snäckor från de områden där kläckningsförsök och rekryteringsstudier genomfördes, visade att det åtminstone detta år inte förekom larver eller cerkarier ögonsugmasken Diplostomum sp. under den känsliga period då fisklarver kan dödas av parasitangrepp. Eutrofiering har förts fram som en tänkbar orsak till den sviktande fiskrekryteringen. Närsaltsdata visar att området är övergött, och en förändrad kväve/fosforkvot antyder att primärproduktionen blivit alltmer kvävebegränsad under produktionsperioden senare år.Eutrofieringen yttrar sig som en ökning av primärproduktionen. Halterna klorofyll-a har tenderat att öka i de kustnära vattnen och bedöms som höga enligt Naturvårdsverkets bedömningsgrunder för miljökvalitet, Kust och Hav (1999). Under de senaste 4-5 åren har halterna emellertid sjunkit, vilket kan kopplas till ökat siktdjup. Utvecklingen indikerar att en större del av primärproduktionen under senare år sker i det bentiska växtsamhället. Denna utveckling ses inte i referensområdena. Även om en rik bottenvegetation normalt är positivt för fisk, kan alltför kraftig algpåväxt ha flera negativa effekter, t ex att leksubstraten försämras. En förskjutning av produktionen från pelagiska mikroalger till det bentiska systemet kan också innebära att fiskens födotillgång påverkas. Analyserna av zooplanktonproven visade tydliga avvikelser jämfört med referensmaterialen, såväl vad avser artsammansättning som täthet, och indikerar att födounderlaget försämrats för pelagiska fisklarver, t ex abborre, strömming och stubbar.Utsläppen från Mönsterås Bruk har också ansetts utgöra en möjlig förklaring. Om skadorna på fisk beror på eutrofiering, kan effekterna av brukets utsläpp ses som ett bidrag bland andra till den antropogena belastningen i området. Risken för att toxiska eller hormonellt störande ämnen i avloppsvattnet påverkat fisken måste enligt resultaten från fält och laboratorieexperimenten bedömas vara liten.Kalmarsund hyser landets tätaste skarvkolonier. Teoretiska beräkningar, baserat på uppskattningar av skarvbeståndets storlek, visar att dess konsumtion skulle kunna uppgå till den totala produktionen av stationär fisk i området vilket kan vara en viktig förklaring till de minskande tätheterna. Det finns dock observationer som talar mot skarven som den enda bakomliggande faktorn. Årsyngel utnyttjas normalt inte som föda av skarvarna, och rekryteringen försämrades inte bara för de stationära arterna abborre och gädda, utan även för stubbar och sillar vars vuxna bestånd inte påverkas lika starkt av skarv. Modellsimuleringar visar dock, att i dagens situation kan skarvpredationen effektivt motverka att bestånden återhämtar sig när, förhoppningsvis, rekryteringen åter börjar bli normal.
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| 16. |
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| 17. |
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| 18. |
- Andersson Lundgren, Andreas, 1970-
(författare)
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Molecular gas in the galaxy M83 : Its distribution, kinematics, and relation to star formation
- 2004
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The barred spiral galaxy M83 (NGC5236) has been observed in the 12CO J=1–0 and J=2–1 millimetre lines with the Swedish-ESO Submillimetre Telescope (SEST). The sizes of the CO maps are 100×100, and they cover the entire optical disk. The CO emission is strongly peaked toward the nucleus. The molecular spiral arms are clearly resolved and can be traced for about 360º. The total molecular gas mass is comparable to the total Hi mass, but H2 dominates in the optical disk.Iso-velocity maps show the signature of an inclined, rotating disk, but also the effects of streaming motions along the spiral arms. The dynamical mass is determined and compared to the gas mass. The pattern speed is determined from the residual velocity pattern, and the locations of various resonances are discussed. The molecular gas velocity dispersion is determined, and a trend of decreasing dispersion with increasing galactocentric radius is found.A total gas (H2+Hi+He) mass surface density map is presented, and compared to the critical density for star formation of an isothermal gaseous disk. The star formation rate (SFR) in the disk is estimated using data from various star formation tracers. The different SFR estimates agree well when corrections for extinctions, based on the total gas mass map, are made. The radial SFR distribution shows features that can be associated with kinematic resonances. We also find an increased star formation efficiency in the spiral arms. Different Schmidt laws are fitted to the data. The star formation properties of the nuclear region, based on high angular resolution HST data, are also discussed.
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| 19. |
- Andersson, Magnus, et al.
(författare)
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Scaling of the vortex-liquid resistivity in optimally doped and oxygen-deficient YBa2Cu3O7-delta single crystals
- 2001
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 63:18, s. 1845111-1845119
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Tidskriftsartikel (refereegranskat)abstract
- The consequences of a recently proposed model [A. Rydh. O. Rapp. and M. Andersson. Phys. Rev. Lett. 83. 1850 (1999)] for the vortex-liquid resistivity close to a vortex liquid-to-glass transition are anal-zed in detail. We find a detailed quantitative agreement between the model and resistivity measurements on disordered, optimally doped YBa2Cu3O7-delta single crystals. For temperatures below the superconducting transition temperature. a scaling of all measured resistivity curves in magnetic field (0
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| 20. |
- Andersson, Magnus, et al.
(författare)
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Vortex liquid properties in optimally doped and oxygen-deficient YBa2Cu3O7-delta single crystals
- 2000
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Ingår i: Physica. C, Superconductivity. - 0921-4534 .- 1873-2143. ; 332:1-4, s. 86-92
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Tidskriftsartikel (refereegranskat)abstract
- The electrical anisotropy, gamma = (m(c)/m(ab))(1/2), can easily be varied by changing the oxygen content in single crystals of YBa2Cu3O7-delta (YBCO); thus making this system useful as a test system For vortex dynamics in high-temperature superconductors (HTSC). Here, some recent results are reviewed. Measurements of the c-axis resistivity with the magnetic field B II ab-plane is shown to be a powerful tool in studying vortex velocity correlations both parallel and perpendicular to the applied field. In optimally doped crystals, we iind evidence that the in-plane vortex lattice melts at T-m into a disentangled vortex liquid, which looses its correlation along the c-axis at a higher temperature T-br > T-m. For weakly disordered crystals and magnetic fields B \\ c-axis, a relation between the vortex glass line and the magnetic field dependence of the characteristic energy, U*, in the pinned vortex liquid is proposed. This approach is shown to give support to our idea of describing the vortex glass resistivity in the liquid regime by a modified glass correlation Length, xi(g) = xi(0)\k(B)T/U-0 - 1\(-nu) which depends on the average pinning energy, Lr,, in the system [A. Rydh, O. Rapp, M. Andersson, Phys. Rev. Lett. 83 (1999) 1850].
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| 21. |
- Andersson, Magnus, et al.
(författare)
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Vortex liquid resistivity in disordered YBa2Cu3O7-delta single crystals
- 2000
-
Ingår i: Physica. C, Superconductivity. - 0921-4534 .- 1873-2143. ; 341, s. 1239-1240
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Tidskriftsartikel (refereegranskat)abstract
- The vortex solid-to-liquid transition line, T-g(B) and the linear resistivity in the vortex liquid of an optimally doped disordered YBa2Cu3O7-delta Single crystal is analyzed in detail. Our previously proposed description [Rydh, Rapp and Andersson, Phys.Rev.Lett. 83 (1999) 1850] is shown to quantitatively describe both T-g(B) and the vortex liquid resistivity above T-g using the same parameters. Furthermore, a comparison with the thermally activated behaviour usually employed to account for the resistivity in the vortex liquid is reported.
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| 22. |
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| 23. |
- Andersson, Per, et al.
(författare)
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Recognition of Prior Vocational Learning in Sweden
- 2004
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Ingår i: Studies in the Education of Adults. - 0266-0830 .- 1478-9833. ; 36:1, s. 57-71
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Tidskriftsartikel (refereegranskat)abstract
- Initiatives in the recognition of prior learning (RPL) have been taken in Sweden in recent years, mainly focusing on prior vocational learning among immigrants. The government started different projects to find methods for recognising a person’s prior learning in the field of vocational competence. This article presents a study of how these projects were organised and their starting points. Differences are identified concerning whether they were integrated with, or parallel to, the school system, and whether the starting point was a few vocations or a number of different vocations (depending on the background of the participants). The article then looks at some problems that arise when trying to recognise prior learning. We find that knowledge of the Swedish language is essential in this process, but that the demands are flexible and the criteria informal. The article also discusses the relationship between RPL and the educational system, where most of the projects had problems in not being too influenced by the school tradition where the main documentation of competence is grades. Finally, the article discusses conditions for the development of trust in RPL.
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| 24. |
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| 25. |
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| 26. |
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| 27. |
- Elmqvist, Thomas, et al.
(författare)
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The Dynamics of Social-Ecological Systems in Urban Landscapes
- 2004
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Ingår i: Annals of the New York Academy of Sciences. - : Wiley. - 0077-8923 .- 1749-6632. ; 1023, s. 308-322
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Tidskriftsartikel (refereegranskat)abstract
- This study addresses social-ecological dynamics in the greater metropolitan area of Stockholm County, Sweden, with special focus on the National Urban Park (NUP). It is part of the Millennium Ecosystem Assessment (MA) and has the following specific objectives: (1) to provide scientific information on biodiversity patterns, ecosystem dynamics, and ecosystem services generated; (2) to map interplay between actors and institutions involved in management of ecosystem services; and (3) to identify strategies for strengthening social-ecological resilience. The green areas in Stockholm County deliver numerous ecosystem services, for example, air filtration, regulation of microclimate, noise reduction, surface water drainage, recreational and cultural values, nutrient retention, and pollination and seed dispersal. Recreation is among the most important services and NUP, for example, has more than 15 million visitors per year. More than 65 organizations representing 175,000 members are involved in management of ecosystem services. However, because of population increase and urban growth during the last three decades, the region displays a quite dramatic loss of green areas and biodiversity. An important future focus is how management may reduce increasing isolation of urban green areas and enhance connectivity. Comanagement should be considered where locally managed green space may function as buffer zones and for management of weak links that connect larger green areas; for example, there are three such areas around NUP identified. Preliminary results indicate that areas of informal management represent centers on which to base adaptive comanagement, with the potential to strengthen biodiversity management and resilience in the landscape.
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| 28. |
- Fejes, Andreas, 1977-, et al.
(författare)
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Recognition of prior professional learning
- 2003
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Ingår i: Nordic Educational Research Association Conference,2003. ; , s. 20-20
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Initiatives in recognition of prior professional learning among immigrants have been taken in Sweden during the last years. The government started different projects aiming at finding methods for recognising aperson-s prior learning in the field of professional competence. This paper presents a study of how these projects were organised and what the starting points of them were. We also lookupon some problems arising when you try to recognise priorlearning. We found that the level of language knowledge in Swedishis essential in this process and that most of the projects had problems leaving the classical school tradition where the maindocumentation of competence is grades.
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| 29. |
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| 30. |
- Hinz, Andreas, et al.
(författare)
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An investigation of the reaction mechanism for the promotion of propane oxidation over Pt/Al2O3 by SO2
- 2001
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Ingår i: Journal of Catalysis. - : Elsevier BV. - 0021-9517 .- 1090-2694. ; 201:2, s. 247-257
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Tidskriftsartikel (refereegranskat)abstract
- Total oxidation of propane with oxygen in the absence and the respective presence of SO2 in the feed gas was studied over 1 wt% Pt on gamma-Al2O3 using transient experiments with TAP (temporal analysis of products) and in situ DRIFT spectroscopy. The TAP experiments confirm the promoting role of SO2 on the conversion of propane and, moreover, show an inhibiting effect from SO2 on the conversion of the intermediate products propene and CO. In situ DRIFT spectroscopy reveals the formation of sulphate species on the catalyst surface and indicates the formation of an allylic intermediate in the absence of SO2 only. Interaction between hydrocarbon intermediates and the sulphate species is confirmed by the appearance of thiol fragments in the mass spectra. The transient experiments show that propane in the first step is irreversibly adsorbed at the surface. Analysis of the surface residence times of the products formed at the propane pulse in pump-probe experiments provides information about the reaction pathways. Without S02 in the feed gas, propane reacts consecutively in the sequence propane --> propene -->. ethane --> CO --> CO2. In the presence of SO2 the first step of the main route is the breaking of a C-C bond in propane producing ethane and a C-1 fragment, which then form CO and eventually CO2. It is suggested that the promoting effect by SO2 on the conversion of propane is due to the formation of an acidic site at the Pt/Al2O3/SO42-interface.
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| 31. |
- Johansson, Andreas, et al.
(författare)
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Influence from the cross-angle on piston forces and bending moments in variable hydraulic piston pumps
- 2003
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- By implementing an additional incline (cross-angle) of the swash plate of an axial piston pump, in the direction perpendicular to the traditional displacement direction, the piston dead-centre points will move as the displacement angle varies. The cross-angle is fixed and normally very small (1-4°). If designed correctly, the movement of the dead-centre points achieved by using a cross-angle coincides with the dead centres desired for optimal cylinder pre-compression and decompression for all displacement angles. It has in earlier works been described how the cross-angle enables minimisation of discharge and inlet peak-to-peak flow ripple for all displacement angles simultaneously. In this paper, it is also investigated how the piston forces and the bending moments are influenced.The cross-angle is designed using simulation-based multi-objective optimisation. It is investigated how objective functions can be made up from peak-to-peak values as well as from frequency spectrum of signals. The trade-offs between the conflicting objectives considered are elucidated by using the concept of Pareto optimality. The result from such a Pareto optimisation is not one optimal solution, but a set of optimal solutions. With the technique presented, it is thus possible to investigate an optimal value for the cross-angle that the most beneficial impact on all factors that influence the noise level of the pump.
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| 32. |
- Johansson, Andreas, et al.
(författare)
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Optimal design of the cross-angle for pulsation reduction in variable displacement pumps
- 2002
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Ingår i: Power Transmission and Motion Control: PTMC 2002. - : Wiley-Blackwell. - 1860583792 - 9781860583797 ; , s. 319-333
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Konferensbidrag (refereegranskat)abstract
- The cross-angle, illustrated in this paper, is a fixed displacement angle around the axis perpendicular to the normal trunnion axis. With the cross-angle, the traditional piston dead centres will change as the normal displacement angle is varied. The result is a behaviour similar to thal of the revolving valve plate technique. but without any movable parts. When the cross-angle is used in a constant pressure system with a variable pump, the desired dead centre for optimal pro-compression coincides with the obtained dead centre for a wide range of displacement angles. This implies that when the cross-angle is used, the flow ripple becomes less sensitive to changes in displacement angles. The cross-angle does not constitute an alternative to the different design features developed, but rather as complement for preserved effective flow ripple reduction over a wide range of displacement angles.ln this study. simulation-based optimisations, employing non-gradient optimisation techniques such as genetic algorithms and the Complex method, are used in order to find the optimal cross-angle for a variable displacement pump. Furthermore. with the help of optimisation, the trade-offs between attributes such as low flow ripples, avoidance of large cylinder pressure-peaks, and cavitation have been studied. Increased insight is thereby gained into what possibilities the cross-angle offers regarding reduction of pump ripple for a variable displacement pump.
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| 33. |
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| 34. |
- Knutsson, Hans, 1950-, et al.
(författare)
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Motion artifact reduction in MRI through generalized DFT
- 2004
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Ingår i: Biomedical Imaging: Nano to Macro, 2004. IEEE International Symposium on. - : IEEE. - 0780383885 ; , s. 896-899 vol.1
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Konferensbidrag (refereegranskat)abstract
- This paper presents a method that dramatically reduces artifacts caused by respiratory (and similar types of) patient motion in magnetic resonance imaging (MRI). The basis for the method is the observation that affine deformations of an object will correspond to a different but unique affine coordinate transform (plus phase shift) of the Fourier representation of the object. The resulting sample points will be irregularly distributed prohibiting the use of standard IFFT to reconstruct the object. The object can however be reconstructed through the use of a weighted regularized pseudo inverse. A standard pseudo inverse is, however, not possible due to excessive computational demands. For this reason a novel fast sequential pseudo inverse algorithm is also presented. Significantly improved results are obtained on both synthetic and clinical data.
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| 35. |
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| 36. |
- Malmquist, Andreas
(författare)
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Kryptogamer och skalbaggar i tre ekområden i Kronobergs län : - inventering och miljöövervakning -
- 2000
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Inledning Kryptogamer och hålträdslevande skalbaggar knutna till äldre grova ädellövträd har inventerats på två lokaler i kronobergs län, nämligen Enhaholm i Alvesta kommun och Toftaholm i Ljungby kommun. På en tredje lokal i Kronobergs län, Yxkullsund i Ljungby kommun, har en mer översiktlig kryptogaminventreing gjorts vid sidan av skalbaggsinventeringen. På sistnämnda lokal har en ett förslag til avgränsning för ett naturreservat gjorts. Alla lokaler är belägna vid gods eller herrgårdar, miljöer som hyser ett stort andel av Sveriges grova och gamla lövträd. Inventeringen av kryptogamer har framförallt inriktats på epifytiska lavar, en grupp som har visat sig användbar i miljöövervakningssyfte....Arbetet har utförts på uppdrag av Länsstyrelsen i Kronobergs län...Inventeringar och övrigt fältarbete genomfördes under juli och augusti år 2000.
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| 37. |
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| 38. |
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| 39. |
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| 40. |
- Olofsson, Göran, et al.
(författare)
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A transient response study of the selective catalytic oxidation of ammonia to nitrogen on Pt/CuO/Al2O3
- 2004
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Ingår i: Chemical Engineering Science. - : Elsevier BV. - 0009-2509. ; 59:19, s. 4113-4123
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Tidskriftsartikel (refereegranskat)abstract
- The reaction mechanism for the selective catalytic oxidation of ammonia to give nitrogen on CuO/Al2O3, Pt/Al2O3 and Pt/CuO/Al2O3 was investigated using transient experiments. Temperature-programmed desorption and reaction of adsorbed ammonia indicated the formation of NHx species at the surface, and that this species is the precursor for the formation of nitrogen and nitrogen oxides. Pt/CuO/Al2O3 is the most active sample for nitrogen formation. In experiments pulsing alternately ammonia and oxygen it is observed that nitrogen is predominantly formed at the oxygen pulse on Pt/CuO/Al2O3 and at the ammonia pulse on Pt/Al2O3 and CuO/Al2O3. Results obtained in the alternate pulsing of ammonia and NO over preoxidised samples exclude NO from being a reaction intermediate for nitrogen formation. The performance of Pt/Al2O3 and CuO/Al2O3 in NH3-NO2 alternate pulsing reveals that nitrogen formation on these two samples occurs by formed NO2 reacts with an NHchi species. Over Pt/CuO/Al2O3, on the other hand, most nitrogen is formed by the direct oxidation and combination of two NHchi species using adsorbed oxygen. The data obtained suggests that the reaction takes place at the Pt/CuO phase boundary between NHx species being adsorbed on CuO and oxygen on Pt sites. (C) 2004 Elsevier Ltd. All rights reserved.
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| 41. |
- Palmqvist, Anders, 1966, et al.
(författare)
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LOTUS: A co-operation for low temperature urea-based selective catalytic reduction of NOx
- 2004
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Ingår i: SAE Technical Papers. - 400 Commonwealth Drive, Warrendale, PA, United States : SAE International. - 0148-7191 .- 2688-3627. ; 20014
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Tidskriftsartikel (refereegranskat)abstract
- The European research co-operation Lotus is presented. The main objectives of the project were i) to show the potential for a urea-based SCR system to comply with the EU standard of years 2005 and 2008 for heavy-duty Diesel engines for different driving conditions with optimal fuel consumption, ii) to reach 95 % conversion of NOx at steady state at full load on a Euro III. engine, iii) to reach 75 % NOx reduction for exhaust temperatures between 200-300°C, and 85 % average NOx reduction between 200-500°C. The energy content of the consumed urea should not exceed 1.0 %, calculated as specific fuel consumption. These targets were met in May 2003 and the Lotus SCR system fulfilled the Euro V NOx legislative objectives for year 2008. Copyright © 2004 SAE International.
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| 42. |
- Rydh, Andreas, et al.
(författare)
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Magnetic field scaling of the vortex glass resistivity in oxygen deficient YBa2Cu3O7-delta single crystals
- 2000
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Ingår i: Physica. B, Condensed matter. - 0921-4526 .- 1873-2135. ; 284, s. 707-708
-
Tidskriftsartikel (refereegranskat)abstract
- The in-plane resistivity of an oxygen deficient YBa2Cu3O7-delta single crystal has been measured as a function of magnetic field B \\ c-axis in the range 0 T less than or equal to B less than or equal to 12 T. A scaling relation is found for the linear resistivity at p less than or similar to 0.1 rho(n) above the glass line that incorporates all studied temperatures and magnetic fields. Our scaling can be understood within a simple model where the mean pinning energy balances the thermal energy at the glass transition, U-0(B, T-g) = k(B)Th(g), with U-0(B, T) resembling a generalized condensation energy, U-0 similar to (1 - T/T-c)(m)/B-beta.
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| 43. |
- Sigfridsson, Andreas, et al.
(författare)
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Retrospective Respiratory Motion Compensation for Cardiac MRI
- 2003
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Konferensbidrag (refereegranskat)abstract
- Cardiac MRI is known to be degraded by respiratory motion. Short scans can be performed using breath-hold techniques, while coronary artery imaging commonly use navigator gated sequences, acquiring data in a known static respiration position.
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| 44. |
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| 45. |
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| 46. |
- Wiklind, Tommy, et al.
(författare)
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Star formation in the nuclear region of M83 : The HST/NICMOS view
- 2004
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Ingår i: The Interplay among Black Holes, Stars and ISM in Galactic Nuclei. - Cambridge : Cambridge University Press. - 0521848032 ; , s. 219-220
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Konferensbidrag (refereegranskat)abstract
- The nuclear region of the barred spiral galaxy M83 has been imaged at near-infrared wavelengths with the HST NICMOS, showing a new region of star formation activity.
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