| 1. |
- Björklund, Henrik, et al.
(författare)
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Compression of finite-state automata through failure transitions
- 2014
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Ingår i: Theoretical Computer Science. - : Elsevier. - 0304-3975 .- 1879-2294. ; 557, s. 87-100
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Tidskriftsartikel (refereegranskat)abstract
- Several linear-time algorithms for automata-based pattern matching rely on failure transitions for efficient back-tracking. Like epsilon transitions, failure transition do not consume input symbols, but unlike them, they may only be taken when no other transition is applicable. At a semantic level, this conveniently models catch-all clauses and allows for compact language representation.This work investigates the transition-reduction problem for deterministic finite-state automata (DFA). The input is a DFA A and an integer k. The question is whether k or more transitions can be saved by replacing regular transitions with failure transitions. We show that while the problem is NP-complete, there are approximation techniques and heuristics that mitigate the computational complexity. We conclude by demonstrating the computational difficulty of two related minimisation problems, thereby cancelling the ongoing search for efficient algorithms.
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| 2. |
- Westblad, Niklas, et al.
(författare)
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The Effect of Autoregulated Flywheel and Traditional Strength Training on Training Load Progression and Motor Skill Performance in Youth Athletes.
- 2021
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Ingår i: International Journal of Environmental Research and Public Health. - : MDPI. - 1661-7827 .- 1660-4601. ; 18:7
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: The effects of flywheel resistance training (FRT) on youth are relatively unknown. The aim of this study was to compare the effects of autoregulated FRT with traditional strength training (TST) on jumping, running performance and resistance training load progression in youth athletes. Thirty youth athletes (11.8 ± 0.9 yr) were matched for peak height velocity (PHV) status and block-randomised into two groups: FRT (n = 15, PHV -0.8 ± 1.6) and TST (n = 15, PHV -0.8 ± 1.5). Twelve resistance training sessions over a six-week intervention with flywheel or barbell squats were performed using autoregulated load prescription. Squat jump (SJ); countermovement jump (CMJ); and 10 m, 20 m and 30 m sprints were assessed pre- and post-intervention. The external load increased similarly for FRT and TST (z = 3.8, p = 0.06). SJ increased for both groups (p < 0.05) but running performance was unaffected (p > 0.05).CONCLUSIONS: FRT resulted in similar load progression and motor skill development in youth athletes as TST, but the perceived exertion was less. Autoregulation is a practical method for adjusting training load during FRT and should be considered as an alternative to autoregulated TST.
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| 3. |
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| 4. |
- Björklund, Camilla, 1977, et al.
(författare)
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Pattern discernment and pseudo-conceptual development in early childhood mathematics education
- 2014
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Ingår i: International Journal of Early Years Education. - : Informa UK Limited. - 0966-9760 .- 1469-8463. ; 22:1, s. 89-104
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Tidskriftsartikel (refereegranskat)abstract
- In this empirical study, we investigate an early childhood education activity in mathematics on the concept of ‘pattern’. The children participating in the study attend an intermediate form of schooling in Sweden called ‘the preschool class for six-year-olds’, intended to facilitate their transition from preschool to school. Following a prolonged activity over 45 minutes, we analyse for what the children are supported in discerning and what they give as evidence of having discerned in and about patterns. The theoretical point of departure is variation theory, conceptualising learning as increased discernment. The results show that in terms of the important Vygotskian distinction between ‘pseudo concepts’ and ‘concepts (proper)’, the children's discernment and what they are supported in discerning are of the former kind. Pseudo concepts are discussed as integral to the institutional form of the preschool class and premised to be important to the child's further conceptual development.
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| 5. |
- Björklund, Johanna, et al.
(författare)
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An efficient best-trees algorithm for weighted tree automata over the tropical semiring
- 2015
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Ingår i: Proc. 9th International Conference on Language and Automata Theory and Applications. - Cham : Springer. ; , s. 97-108
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Konferensbidrag (refereegranskat)abstract
- We generalise a search algorithm by Mohri and Riley from strings to trees. The original algorithm takes as input a weighted automaton M over the tropical semiring, together with an integer N, and outputs N strings of minimal weight with respect to M. In our setting, M defines a weighted tree language, again over the tropical semiring, and the output is a set of N trees with minimal weight. We prove that the algorithm is correct, and that its time complexity is a low polynomial in N and the relevant size parameters of M.
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| 6. |
- Björklund, Johanna, et al.
(författare)
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Efficient enumeration of weighted tree languages over the tropical semiring
- 2019
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Ingår i: Journal of computer and system sciences (Print). - : Elsevier BV. - 0022-0000 .- 1090-2724. ; 104, s. 119-130
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Tidskriftsartikel (refereegranskat)abstract
- We generalise a search algorithm by Mohri and Riley from strings to trees. The original algorithm takes as input a nondeterministic weighted automaton M over the tropical semiring and an integer N, and outputs N strings of minimal weight with respect to M. In our setting, M is a weighted tree automaton, again over the tropical semiring, and the output is a set of N trees with minimal weight in this language. We prove that the algorithm is correct, and that its time complexity is a low polynomial in N and the relevant size parameters of M.
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| 7. |
- Björklund, Johanna, et al.
(författare)
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Syntactic methods for topic-independent authorship attribution
- 2017
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Ingår i: Natural Language Engineering. - : CAMBRIDGE UNIV PRESS. - 1351-3249 .- 1469-8110. ; 23:5, s. 789-806
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Tidskriftsartikel (refereegranskat)abstract
- The efficacy of syntactic features for topic-independent authorship attribution is evaluated, taking a feature set of frequencies of words and punctuation marks as baseline. The features are 'deep' in the sense that they are derived by parsing the subject texts, in contrast to 'shallow' syntactic features for which a part-of-speech analysis is enough. The experiments are made on two corpora of online texts and one corpus of novels written around the year 1900. The classification tasks include classical closed-world authorship attribution, identification of separate texts among the works of one author, and cross-topic authorship attribution. In the first tasks, the feature sets were fairly evenly matched, but for the last task, the syntax-based feature set outperformed the baseline feature set. These results suggest that, compared to lexical features, syntactic features are more robust to changes in topic.
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| 8. |
- Björklund, Mattias, 1971-
(författare)
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Beyond Moral Teaching : Financial Literacy as Citizenship Education
- 2021
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis explores what financial literacy is, what financial literacy becomes and what financial literacy could become within the context of a citizenship education such as the Swedish upper secondary subject of social studies. Financial literacy does not intuitively converge with social sciences which leaves social studies teachers to both teach and realise financial literacy. Thus, teachers become co-creators of financial literacy as a school subject. This thesis explores this process via two different studies resulting in four research articles. In the first study, semi-structured interviews – analysed through PCK – are used to explore the perceptions of Swedish social studies teachers in upper secondary school regarding financial literacy teaching and learning. The findings include differences between experienced and novice teachers regarding which content knowledge and pedagogical approaches they use. However, all teachers express difficulties fitting financial literacy into social studies, mainly due to a perception of financial literacy primarily being a private matter, along with the unclear relationship between financial and societal issues. The second study is designed as a financial literacy teaching intervention. Students’ views on a financial dilemma are analysed using citizenship conceptions and threshold concepts. The findings are used to discuss design principles for financial literacy teaching. Salient conclusions in the thesis include citizenship education being able to frame financial literacy and provide epistemic features which can make financial literacy more teachable and learnable. It is hoped that the results from this thesis can inform future financial literacy teaching design as well as policy discussion related to financial literacy teaching and learning contextualised with another subject, especially citizenship education.
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| 9. |
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| 10. |
- Björklund, Maria, et al.
(författare)
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Kunskapsdelning för grönare logistik, erfarenheter från ett dyadiskt samarbete
- 2024
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Ingår i: Sammanställning av referat från Transportforum 2024. - Linköping : Statens väg- och transportforskningsinstitut. ; , s. 376-377
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Kunskapsdelning mellan aktörer i försörjningskedjor är en viktig möjliggörare för grönare logistik. Flertalet studier framhäver vikten av kunskapsdelning vid exempelvis implementering av grön fordonsteknik, alternativa bränslen, transportslagsbyte och elektriska fordon utan att gå djupare in på vad kunskapsutbytet innebär. I studien har vi strävat efter att besvara frågor av karaktären: Vad är det för sorts kunskap som utbytes?Vilka (ex titlar) spelar centrala roller vid kunskapsutbytet?Hur sker kunskapsutbytandet? I en tvåårig observationsstudie har vi följt ett tjugotal 2-4h möten mellan ett logistikföretag och en transportköpare. Målet med mötena var att identifiera hur de tillsammans kan nå kundens mål, att bli fossilfria till 2023. Den longitudinella ansatsen har även möjliggjort att vi kunnat se förändringar över tid. Ett ramverk baserat på litteratur kring kunskapsutbyte skapades bestående av olika typer (ex. enklare eller komplexare kunskap) och former (ex. vem som ger och vem som får kunskap) av kunskapsutbyte. I empirin fann vi sedan ett starkt fokus på management-orienterad kunskap och utbyte av enklare information. Femton personer närvarade vid mötena vilket visar att samverkan krävde kunskap från individer med olika erfarenheter och ansvarsområden. Det longitudinella perspektivet visar att en del kunskap som var relativt komplex såsom sätt att definiera fossilfri blev enklare när en samsyn uppnåtts. Logistikföretaget hade mest kunskap att donera, samtidigt som det logistikköpande företaget styrde mötena och dialogen. Medan logistikköparen fick en fördjupad förståelse för potentialerna och konsekvenserna i olika potentiella åtgärder, erhöll logistikföretaget djupare insikter kring köparens prioriteringar och förändringsmöjligheter. Tre områden fokuserades i kunskapsutbytet: prestationsstyrning (för att tydliggöra utvecklingen och strävan mot satta mål), olika gröna satsningar (ex. elbilar, HVO1000 och gröna leveransfönster). En tredje aspekt blev med tiden allt tydligare: att de tillsammans blev alltmer beroende av andra aktörer för att erhålla nödvändiga kunskaper. Studien tydliggör den komplexitet som finns i kunskapsutbytet mellan dessa båda aktörer och hur kunskapsutbytet varierar över tid och hur det är beroende av de medverkande i mötet. Studien visar även på att båda aktörerna har kunskap som måste delas för att kunna identifiera de mest framgångsrika lösningarnai deras unika kontext.
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| 11. |
- Björklund, Maria, 1973-, et al.
(författare)
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Nära aktörssamverkan för hållbar logistik : vad innebär det i praktiken?
- 2022
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Ingår i: Supply chain effect. ; :5, s. 32-37
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Tidskriftsartikel (populärvet., debatt m.m.)abstract
- Det finns en uppsjö av studier som pekar på vikten avnära samverkan över företagsgränser för en hållbar om-ställning av logistiken. Men hur ser egentligen dennasamverkan ut? Hur möts företagen? Vad pratar de om?Hur är stämningen i rummet? Vilka nya satsningar föds urdenna typ av samverkan?
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| 12. |
- Björklund, Maria, 1973-, et al.
(författare)
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Roles and Perspectives When Estimating Energy and Environmental Potentials of Urban Consolidation
- 2019
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Ingår i: Energies. - : MDPI. - 1996-1073. ; 12:24, s. 4811-
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Tidskriftsartikel (refereegranskat)abstract
- Urban consolidation centers (UCCs) are presumed to provide more efficient goods distribution in cities and lead to decreased environmental impact and energy usage. There is, however, limited knowledge as to the actual performance of UCCs, and what roles and perspectives the involved actors have in the performance measurement. The overall aim of this paper is to investigate the roles and perspectives of involved actors when estimating and evaluating the performance of UCCs. The article is based on a study of one case that evaluates the performance of a UCC involving several actors. Interviews were triangulated with documents from the case. The results showed that actors have different roles in performance measurements and even if they share a mutual interest in conducting the measurements, they did not share opinions regarding factors such as system limits or performance indicators. The study provides a deeper understanding of the importance of inter-organizational interaction when conducting performance measurements. The study provides additional insights into the roles of the actors and their perspectives in logistics performance measurement that targets energy usage and environmental impact. These aspects are seldom addressed in less complex estimations or mathematical modelling estimations.
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| 13. |
- Björklund, Maria, 1973-, et al.
(författare)
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Who is driving towards sustainable transportation?
- 2019
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Ingår i: Paper presented at the National conference in transport research, Linköping Sweden, October 22-23, 2019. - : Linköping University.
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Konferensbidrag (refereegranskat)
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| 14. |
- Björklund, Niklas, et al.
(författare)
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Assessing the confidence in pest freedom gained in the past pine wood nematode surveys
- 2023
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Ingår i: EFSA supporting publications. - 2397-8325. ; 20
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Tidskriftsartikel (refereegranskat)abstract
- All Member States of the European Union must conduct annual surveys of pine wood nematode (PWN) to ensure its timely detection. However, the statistical confidence of these surveys is rarely assessed. To facilitate such assessments, we developed two easy-to-use web applications: NoBaSURV-PWN for assessment of the statistical confidence of past PWN surveys, and NoBa Land Cover Retriever for retrieving the land cover data needed in the assessments. This report explains how the statistical confidence of past PWN surveys can be assessed with NoBaSURV-PWN. In addition, the reportpresents the assessments done with the NoBaSURV-PWN applicationfor Estonia, Finland, Lithuania, Norway, and Sweden. The technical details of the developed applications are presented,and some matters that have general relevance for statistical assessment and planning of quarantine pest surveys are discussed. Also, the capacity building activitiesdone in the project are described and their impact is evaluated.The assessments forthe five Nordic-Baltic countries show that, in most of the countries, PWN surveys have been extensive enough to provide evidence for facilitating tradewith a rather high confidence. Yet, the surveys have clearly not been extensive enough to ensure detection of PWN invasions at such an early stage that they could be eradicated.
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| 15. |
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| 16. |
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| 17. |
- Björklund, Niklas
(författare)
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Climate change and range expansion of an aggressive bark beetle: evidence of higher beetle reproduction in naive host tree populations
- 2010
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Ingår i: Journal of Applied Ecology. - : Wiley. - 0021-8901 .- 1365-2664. ; 47, s. 1036-1043
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Tidskriftsartikel (refereegranskat)abstract
- 5. Synthesis and applications. The current study demonstrates that the mountain pine beetle has higher reproductive success in areas where its host trees have not experienced frequent beetle epidemics, which includes much of the current outbreak area in north central British Columbia. This increased productivity of mountain pine beetle is likely to have been a key reason for the rapid population buildup that resulted in unprecedented host tree mortality over huge areas in western Canada. The outbreak thus provides an example of how climate change-driven range expansion of native forest insects can have potentially disastrous consequences. Since an increased reproductive success is likely to accelerate the progression of outbreaks, it is particularly critical to manage forests for the maintenance of a mosaic of species and age classes at the landscape level in areas where host tree populations are naive to eruptive herbivores.
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| 18. |
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| 19. |
- Björklund, Niklas, et al.
(författare)
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Erroneous conclusions about current geographical distribution and future expansion of forest insects in Northern Sweden: comments on Hof and Svahlin (2015)
- 2016
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Ingår i: Scandinavian Journal of Forest Research. - : Informa UK Limited. - 0282-7581 .- 1651-1891. ; 31, s. 126-127
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Tidskriftsartikel (refereegranskat)abstract
- We question the validity of the results and the conclusions from a study entitled The potential effect of climate change on the geographical distribution of insect pest species in the Swedish boreal forest that was recently published in Scandinavian Journal of Forest Research. The main problem is that for several of the species the current geographical distributions presented in the paper (based on modeling of a limited set of occurrence data) are vastly underestimated compared with distribution maps in standard reference literature and other available occurrence data. As a consequence of that the predicted major future range expansions of these important pest species are also erroneous.
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| 20. |
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| 21. |
- Björklund, Niklas, et al.
(författare)
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Exploiting jasmonate-induced responses for field protection of conifer seedlings against a major forest pest, Hylobius abietis
- 2014
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Ingår i: Forest Ecology and Management. - : Elsevier BV. - 0378-1127 .- 1872-7042. ; 313, s. 212-223
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Tidskriftsartikel (refereegranskat)abstract
- Herbivore damage commonly initiates an increased synthesis of chemical defensive compounds in attacked plants. Such induced defences are a vital part of plant defence systems, but when herbivore pressure is high, as frequently occurs in man-made ecosystems such as agricultural and forest plantations, plants may suffer considerable damage before adequate induced defences build up. To prepare the plants for such conditions their induced defence may be artificially triggered by the exogenous application of different phytohormones involved in damage signalling. This method is already employed in agriculture but within forestry systems it has so far been restricted to promising laboratory results. The pine weevil, Hylobius abietis, causes damage by feeding on the bark of young conifer plants and it is one of the main threats to successful regeneration in the Palaearctic region. Here we present results from a large scale field experiment where we triggered the induced defences of conifer seedlings using exogenous application of the chemical elicitor methyl jasmonate. To enhance the generality of the results different species were planted under extremely different environmental conditions; Maritime pine and Monterrey pine in Spain, and Scots pine and Norway spruce in Sweden. Weevil damage, chemical defences, and seedling growth were studied during the two growing periods following planting. In general, treated plants showed increased quantitative defences, and were less attacked, less wounded, less girdled and showed lower mortality rates than their untreated counterparts. Effects were mostly dose dependent, although some interactive effects with tree species were observed. The treatment initially caused a growth reduction but it was later compensated by the benefit, in terms of growth, of being less damaged. The measures that are currently taken to protect forest plantations against this harmful pest all around Europe have enormous economic costs and cause important environmental hazards. Elicitation of inducible defences in seedlings in the nursery appears to be an attractive alternative to these measures. To our knowledge, this is the first field study that explores the applicability of chemical elicitors of induced defences as a way to protect forest plantations against biotic threats. (C) 2013 Elsevier B.V. All rights reserved.
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| 22. |
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| 23. |
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| 24. |
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| 25. |
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| 26. |
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| 27. |
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| 28. |
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| 29. |
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| 30. |
- Björklund, Niklas, et al.
(författare)
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Fungal inoculation and methyl jasmonate application induce highly variable terpene accumulation in Norway spruce
- 2012
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Knowledge about tree chemical defense is vital for developing practical methods to maintain healthy forests. With the aims of characterizing the defensive chemical induction in Norway spruce Picea abies and demonstrating its ecological function to spruce bark beetle Ips typographus, we measured the terpenoid content in the bark of mature Norway spruce trees inoculated with Ceratocystis polonica, or treated with methyl jasmonate (MeJA), and investigated the colonization and pheromone emission of I. typographus.
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| 31. |
- Björklund, Niklas
(författare)
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Granbarkborrar, fångstvirkesfällor och angripen skog
- 2009
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Fångstvirkesfällorna minskar angreppen i undersökningsområdet. Skyddseffekten uppmättes till 60 m från fällorna. Angreppen kan öka i fällans omedelbara när-område, närmare än 10-15 m
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| 32. |
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| 33. |
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| 34. |
- Björklund, Niklas
(författare)
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Inget entydigt resultat av ombehandlingar
- 2012
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Ingår i: Skogseko. - 0346-0495. ; 2, s. 42-
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Tidskriftsartikel (populärvet., debatt m.m.)abstract
- En ombehandling med insekticid kan ge en kraftig reduktion av snytbaggeskadorna under vissa omständigheter och knappt någon alls under andra. Här sammanfattas vad vi från forskarhåll vet om detta.
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| 35. |
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| 36. |
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| 37. |
- Björklund, Niklas, et al.
(författare)
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Mitochondrial DNA haplotypes indicate two postglacial re-colonization routes of the spruce bark beetle Ips typographus through northern Europe to Scandinavia
- 2014
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Ingår i: Journal of Zoological Systematics and Evolutionary Research. - : Hindawi Limited. - 0947-5745 .- 1439-0469. ; 52, s. 285-292
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Tidskriftsartikel (refereegranskat)abstract
- Species in northern Europe re-colonized the region after the last glacial maximum via several routes, which could have lingering signatures in current intraspecific trait variation. The spruce bark beetle, Ips typographus, occurs across Europe, and biological differences have been found between southern and northern Scandinavian populations. However, the postglacial history of I. typographus in Scandinavia has not been previously studied at a fine geographical scale. Therefore, we collected specimens across northern Europe and analysed the genetic variation in a quite large mitochondrial fragment (698 bp). A high genetic diversity was found in some of the most northern populations, in the Baltic States, Gotland and central Europe. Detected genetic and phylogeographic structures suggest that I. typographus re-colonized Scandinavia via two pathways, one from the northeast and one from the south. These findings are consistent with the re-colonization history of its host plant, Picea abies. However, we observed low haplotype and nucleotide diversity in southern Scandinavian populations of I. typographus, indicating that (unlike P. abies) it did not disperse across the Baltic Sea in multiple events. Further, the divergence among Scandinavian populations was shallow, conflicting with a scenario where I. typographus expanded concurrently with its host plant from a 'cryptic refugium' in the northwest.
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| 38. |
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| 39. |
- Björklund, Niklas
(författare)
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Non-destructive tree-trunk funnel trap for capturing Hylobius warreni (Coleoptera: Curculionidae) ascending stems of trees
- 2009
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Ingår i: Canadian Entomologist. - : Cambridge University Press (CUP). - 0008-347X .- 1918-3240. ; 141, s. 422-424
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Tidskriftsartikel (refereegranskat)abstract
- A simple and inexpensive non-destructive trap to catch insects as they ascend tree boles is described. The trap was tested in a capture-mark-recapture experiment on the Warren root collar weevil, Hylobius warreni Wood. A high percentage (77%) of marked H. warreni were recaptured at least once during a 12-day period and 54% were recaptured more than once, with one weevil recaptured eight times.
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| 40. |
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| 41. |
- Björklund, Niklas
(författare)
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Pest risk assessment of Eotetranychus lewisi for the EU territory
- 2017
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Ingår i: EFSA Journal. - : Wiley. - 1831-4732. ; 15
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Based on the pest categorisation prepared by EFSA, E. lewisi has the potential to be both a quarantine pest, as it fulfils all ISPM 11 criteria, and a Non-Regulated Quarantine Pest, as it fulfils all ISPM 21 criteria. However, it is noted that information on the potential impact is very limited. At the same time, the organism is currently regulated only for plants of Citrus L., Fortunella Swingle, Poncirus Raf. and their hybrids. However, the affected host range is broader than what is currently covered. There are major hosts such as plants of Euphorbia, Rubus, Fragaria, Prunus, Vitis, etc. which are not regulated for this specific organism. In the European Union (EU), it has been found, for example, also on plants of Corokia cotoneaster in 1999. The pathways of spreading are numerous. The Working Group recommends to keep this organism as Union Quarantine Pest. To support further decisions on risk reduction options, the PRA process has to continue. In particular, EFSA is asked to focus further work on the probability of entry of the pest (identification of the pathways), its establishment, as well as further spread after its establishment in the EU. It is important to explore as well the reasons for its absence in the EU. Additional information as regards the degree of impact would be also relevant even though the Working Group above acknowledges the absence of data in this respect.
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| 42. |
- Björklund, Niklas
(författare)
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Population size estimation for the Warren root collar weevil, Hylobius warreni Wood (Coleoptera: Curculionidae), a pest of regenerating lodgepole pine plantations
- 2021
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Ingår i: Journal of the Entomological Society of British Columbia. - 0071-0733 .- 1929-7890. ; 118, s. 12-18
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Tidskriftsartikel (refereegranskat)abstract
- The Warren root collar weevil, Hylobius warreni Wood (Coleoptera: Curculionidae), is an endemic pest species of conifers, particularly lodgepole pine (Pinus contorta var. latifolia) (Pinaceae), in British Columbia. Larvae feed on the roots and root collars of young trees, resulting in girdling damage and mortality or growth reductions. Population sizes of adult H. warreni have historically been difficult to assess due to a lack of operational sampling methods or chemical attractants for the species. Therefore, most previous population estimates have relied on indirect or incomplete measures of damage by immature individuals. In this study, we tested the Björklund funnel trap to assess its efficacy as a method to estimate H. warreni populations. Funnel traps were placed on all 182 trees in half of a small (~1 ha) lodgepole pine stand over four days and remained in place for 13 days after the last traps were installed. Adult weevils were captured, marked, and released on the bole of the tree on which they had been caught. It is likely that most of the adult weevils in the plot, which was isolated from any nearby lodgepole pine stands, were caught at least once and many were caught multiple times. Population sizes were estimated using both the Schnabel method and the Schumacher and Eschmeyer method, resulting in population estimates of 1.83-2.19 weevils/tree and 731-875 weevils/ha. These measures are within the range of population sizes estimated by previous studies. The results suggest the Björklund funnel trap may be an effective operational tool for population monitoring for this species and may also be an effective tactic in population reduction strategies.
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| 43. |
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| 44. |
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| 46. |
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| 47. |
- Björklund, Niklas
(författare)
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Random and directed movement by Warren root collar weevils (Coleoptera: Curculionidae), relative to size and distance of host lodgepole pine trees
- 2020
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Ingår i: Journal Of Insect Science (Online). - : Oxford University Press (OUP). - 1536-2442. ; 20
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Tidskriftsartikel (refereegranskat)abstract
- Hylobius warreni Wood (Coleoptera: Curculionidae) is a pest of conifers, especially lodgepole pine (Pinus contorta var. latifolia Douglas ex Loudon) (Pinales: Pinaceae) in the Interior of British Columbia. The larvae feed on the roots and root collars and cause girdling damage, resulting in mortality or growth reductions. Previous research has suggested the adult weevils locate potential host trees by using random movements and vision, but likely not chemosensory cues. The purpose of this study is to determine if adult H. warreni respond to particular tree characteristics versus encounter potential hosts at random. Study A was a capture–mark–recapture experiment where weevils were captured on mature pine trees, while Study B was a tracking experiment within a young pine plantation. Weevils showed a preference for larger trees, and for trees that were closer to the weevil’s last known location. In Study A, weevils also avoided climbing trees in poor health, while in Study B, the weevils’ preference for taller trees increased as their distance from the weevil increased, as well as when taller trees were closer to other trees. Movement rates were similar to those observed in previous studies, were positively correlated with the average spacing of trees, and declined with time after release. This confirms previous findings that H. warreni may locate host trees by both vision and random movements, and that their movements are determined primarily by the size and distribution of potential host trees within their habitat.
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- Björklund, Niklas, et al.
(författare)
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Rapid Pest Risk Analysis Xyleborinus attenuatus
- 2017
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- This rapid pest risk analysis (PRA) provides a quick assessment of the risks posed by the pest to Sweden, which is the PRA area being assessed. The format is an adapted version of the EPPO Express PRA scheme (EPPO 2012). Definition of terms used as well as the rating scheme and assessments are done in line with the guidance given in the EPPO CAPRA system (EPPO 2011). The likelihood of entry and establishment are assessed considering the current phytosanitary regulation in place with respect to the EU legislation (Council Directive 2000/29/EC). The definition of a quarantine pest follows the regulation (EU) 2016/2031.
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