| 11. |
- Dahl, Sofia
(författare)
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Movements and analysis of drumming
- 2012
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Ingår i: Music, Motor Control and the Brain. - : Oxford University Press. - 9780199298723 - 9780191700903
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Bokkapitel (refereegranskat)abstract
- This chapter analyses the movement strategies used in drumming. These movement strategies can be described as whiplash-like and aim at achieving high stick velocities on impact. Skilled playing of percussion instruments involves adjusting to and utilising the kinesthetic feedback from the instrument in question. The overall patterns of the movement strategies are maintained consistently for different tempi, surfaces and dynamic levels. The height to which the stick is lifted in preparation for a stroke and the vertical velocity of the stick marker at impact are both strongly linked to the dynamic level.
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| 12. |
- Dahl, Sofia, et al.
(författare)
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Näringsvävsmodellering i Vättern
- 2005
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Del I:S. Dahl & C Rosenqvist, Uppsala UniversitetNäringsvävsmodellering i Vättern.Vättern är en sjö med egenskaper som gör den känslig för miljöpåverkan. Dessa innefattar sjöns oligotrofa karaktär, den sparsamma planktonförekomsten, det stora djupet, den stora volymen och den långa utbytestiden hos vattnet. Koncentrationen av fosfor i sjön har under senare år minskat avsevärt, vilket delvis beror på utsläppsreduktioner från t ex hushållsavlopp och industrier. Beståndet av signalkräfta har vuxit snabbt och nått en stark etablering i delar av Vättern. Fosfor i vattnet binds naturligt i biologiskt material. Förutsatt att allt annat är konstant kan en expansion av signalkräfta innebära en minskning av sjöns totalfosforkoncentration samt en större kvarhållning av fosfor i sjön. En risk om utarmningen av Vätterns näringsstatus får fortgå är att halterna av miljögifter i exempelvis fisk kan stiga då en given mängd av en toxisk substans fördelas på ett färre antal organismer.I examensarbetet har en akvatisk näringsvävsmodell, LakeWeb, anpassats till förhållandena i Vättern och använts för att simulera tillförseln och omsättningen av fosfor i Vättern. Modellen har vidare använts för att utreda vilken betydelse näringshalten i sjön har för kvicksilverhalten i fisk från Vättern samt vilken inverkan utsläpp från den största punktkällan, Aspa bruk, har för fosforhalten i Vättern och kvicksilverhalten i röding. För att bedöma om expansionen av signalkräfta är en signifikant sänka för fosfor och om det expanderande beståndet utgör ett hot mot övriga organismer i Vättern har en utvidgning av modellen gjorts där signalkräftan kommer in som en predator på bottendjur. Massbalansberäkningar visar att Vätterns totala tillförsel av fosfor är 35 ton/år, varav 23 ton fastläggs i sedimenten och 12 ton transporteras ut från sjön via det enda utflödet, Motala ström. Det går med LakeWeb-modellen att på ett bra sätt beskriva effekterna av utsläppsreduktioner. En simulerad halvering av totalfosforkoncentrationen i Vättern ger en ökning av kvicksilverhalten i fisk med 7 %. En fullständig eliminering av fosforutsläppet från Aspa bruk resulterar efter 50 år i en minskning av totalfosforkoncentrationen i Vättern med knappt 1 ¼g/l, vilket motsvarar ca 14 % minskning. En fördubbling av utsläppen resulterar på samma sätt i en 14 % ökning av fosforhalten i Vättern. Kvicksilverhalten i fisk påverkas inte nämnvärt av utsläppsförändringarna. Ett expanderande bestånd av signalkräfta leder till en minskad fosforhalt. Modellsimuleringar visar att Signalkräftan har en betydande inverkan på biomassor av bottendjur och fisk medan påverkan på övriga organismgrupper inte är särskilt stor.Del II: M. Sezter, Högskolan i SkövdeEn näringsvävsanalys för att undersöka storrödingens (Salvelinus umbla) tillbakagång i Vättern.Statistik över yrkesfiskets fångster av röding (Salvelinus umbla) i Vättern finns sedan 1914och den visar att fångsterna successivt har minskat sedan 1950-talet (60-70 ton per år). Deårliga fångsterna inom yrkesfisket har de senaste åtta åren inte överstigit 20 ton per år. Deorsaker till minskningen som undersöks i denna modell är fisketrycket på rödingen,kräftpredation på rom och yngel samt konkurrens med inplanterad lax. En näringsvävsmodellöver Vätterns pelagiska ekosystem, där rödingen är stadiestrukturerad har använts. Lotka-Volterra ekvationen har använts för att beskriva dynamiken i systemet och empirisktinsamlade data (bland annat maganalyser) har använts för att parameterisera modellen.Resultaten visar att fisketrycket har den största effekten på rödingbeståndet och att den storatätheten av signalkräftan respektive utsättningar av laxsmolt inte kan vara de enda orsakernatill rödingbeståndets tillbakagång i Vättern.
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| 13. |
- Dahl, Sofia, 1972-
(författare)
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On the beat : human movement and timing in the production and perception of music
- 2005
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis addresses three aspects of movement, performance and perception in music performance. First, the playing of an accent, a simple but much used and practiced element in drumming is studied, second, the perception of gradually changing tempo, and third, the perception and communication of specific emotional intentions through movements during music performance. Papers I and II investigated the execution and interpretation of an accent in drumming, performed under different playing conditions. Players' movements, striking velocities and timing patterns were studied for different tempi, dynamic levels and striking surfaces. It was found that the players used differing movement strategies and that interpreted the accent differently, reflected in their movement trajectories. Strokes at higher dynamic levels were played from a greater average height and with higher striking velocities. All players initiated the accented strokes from a greater height, and delivered the accent with increased striking velocity compared to the unaccented strokes. The interval beginning with the accented stroke was also prolonged, generally by delaying the following stroke. Recurrent cyclic patterns were found in the players' timing performances. In a listening test, listeners perceived grouping of the strokes according to the cyclic patterns. Paper III concerned the perception of gradual tempo changes in auditory sequences. Using an adaptive test procedure subjects judged stimuli consisting of click sequences with either increasing or decreasing tempo, respectively. Each experiment included three test sessions at different nominal tempi (80, 120, and 180~beats per minute). The results showed that ten of the eleven subjects showed an inherent bias in their perception of tempo drift. The direction and magnitude of the bias was consistent between test sessions but varied between individuals. The just noticeable differences for tempo drift agreed well with the estimated tempo drifts in production data, but were much smaller than earlier reported thresholds for tempo drift. Paper IV studied how emotional intent in music performances is conveyed to observers through the movements of the musicians. Three players of marimba, bassoon, and saxophone respectively, were filmed when playing with the expressive intentions Happiness, Sadness, Anger and Fear. Observers rated the emotional content and movement cues in the videos clips shown without sound. The results showed that the observers were able to identify the intentions Sadness, Anger, and Happiness, but not Fear. The rated movement cues showed that an Angry performance was characterized by jerky movements, Happy performances by large, and somewhat fast and jerky movements, and Sad performances by slow, and smooth movements.
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| 14. |
- Dahl, Sofia
(författare)
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Playing the accent : comparing striking velocity and timing in an ostinato rhythm performed by four drummers
- 2004
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Ingår i: Acta Acoustica united with Acustica. - 1610-1928 .- 1861-9959. ; 90:4, s. 762-776
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Tidskriftsartikel (refereegranskat)abstract
- Four percussion players’ strategies for performing an accented stroke were studied by capturing movement trajectories.The players played on a force plate with markers on the drumstick, hand, and lower and upper arm. Therhythmic pattern – an ostinato with interleaved accents every fourth stroke – was performed at different dynamiclevels, tempi and on different striking surfaces attached to the force plate. The analysis displayed differencesbetween the movement trajectories for the four players, which were maintained consistently during all playingconditions. The characteristics of the players’ individual movement patterns were observed to correspond wellwith the striking velocities and timing in performance. The most influential parameter on the movement patternswas the dynamic level with increasing preparatory heights and striking velocity for increasing dynamic level. Theinterval beginning with the accented stroke was prolonged, the amount of lengthening decreasing with increasingdynamic level.
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| 15. |
- Dahl, Sofia
(författare)
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Striking movements : movement strategies and expression in percussive playing
- 2003
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis concerns two aspects of movement and performancein percussion playing, First, the playing of an accent, asimple but much used and practised element in drumming, andsecond; the perception and communication of specific emotionalintentions through movements during performances onmarimba.Papers I and II investigated the execution andinterpretation of an accent performed for different playingconditions. Players' movements, striking velocities and timingpatterns were studied for different tempi, dynamic levels andstriking surfaces. It was found that the players used differingmovement strategies when playing and that they interpreted theaccent differently, something that was reflected in theirmovement trajectories. Strokes at greater dynamic levels wereplayed from a greater height and with higher strikingvelocities. All players initiated the accented strokes from agreater height, and delivered the accent with increasedstriking velocity compared to unaccented strokes. The intervalbeginning with the accented stroke was also prolonged,generally by delaying the following stroke. Recurrent cyclicpatterns were found in the players' timing performances. In alistening test listeners perceived the strokes groupedaccording to the cyclic patterns.Paper III studied how emotional intent was conveyed toobservers through the movements of a marimba player. Apercussionist was filmed when playing a piece with theexpressive intentions Happiness, Sadness, Anger and Fear onmarimba. Observers rated the emotional content and movementcues in the videos clips shown without sound. Results showedthat the observers were able to identify the intentionsSadness, Anger, and Happiness, but not Fear. The rated movementcues showed that an Angry performance was characterized bylarge, fast, uneven and jerky movements, Happy performances bylarge, somewhat fast movements, and Sad performances by small,slow, even, and smooth movements.Keywords:drumming, percussion, movement strategies,instrument interaction, timing, accent, movement cues emotionalexpression, gesture.
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| 16. |
- Dahl, Sofia
(författare)
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The playing of an accent : Preliminary observations from temporal and kinematic analysis of percussionists
- 2000
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Ingår i: Journal of New Music Research. - : Informa UK Limited. - 0929-8215 .- 1744-5027. ; 29:3, s. 225-233
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Tidskriftsartikel (refereegranskat)abstract
- The movements and timing when playing an interleaved accent in drumming were studied for three professionals and one amateur. The movement analysis showed that the subjects prepared for the accented stroke by raising the drumstick up to a greater height. The movement strategies used, however, differed widely in appearance. The timing analysis showed two basic features, a slow change in tempo over a longer time span ("drift"), and a short ter variation between adjacent intervals ("flutter"). Cyclic patterns, with every fourth interval prolonged, could be seen in the flutter. The lengthening of the interval, beginning with the accented stroke, seems to be a common way for the player to give the accent more emphasis. A listening test was performed to investigate if these cyclic patterns conveyed information to a listener about the grouping of the strokes. Listeners identified sequences where the magnitude of the inter-onset interval fluctuations were large during the cyclic patterns.
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| 17. |
- Dahl, Sofia, et al.
(författare)
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Visual perception of expressiveness in musicians' body movements
- 2007
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Ingår i: Music perception. - : University of California Press. - 0730-7829 .- 1533-8312. ; 24:5, s. 433-454
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Tidskriftsartikel (refereegranskat)abstract
- MUSICIANS OFTEN MAKE GESTURES and move their bodies expressing a musical intention. In order to explore to what extent emotional intentions can be conveyed through musicians' movements, participants watched and rated silent video clips of musicians performing the emotional intentions Happy, Sad, Angry, and Fearful. In the first experiment participants rated emotional expression and movement character of marimba performances. The results showed that the intentions Happiness, Sadness, and Anger were well communicated, whereas Fear was not. Showing selected parts of the player only slightly influenced the identification of the intended emotion. In the second experiment participants rated the same emotional intentions and movement character for performances on bassoon and soprano saxophone. The ratings from the second experiment confirmed that Fear was not communicated whereas Happiness, Sadness, and Anger were recognized. The rated movement cues were similar in the two experiments and were analogous to their audio counterpart in music performance.
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| 18. |
- Dahl, Viktor, 1979-, et al.
(författare)
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The moderating role of political interest : Investigating involvement in institutional and non-institutional political participation among young adults in Sweden
- 2016
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Ingår i: Politics, Culture and Socialization. - : Verlag Barbara Budrich. - 1866-3427 .- 2196-1417. ; 7:1-2, s. 157-181
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Tidskriftsartikel (refereegranskat)abstract
- Many efforts have been made to explain variations in political participation. One such effort was made by Gamson, who hypothesized that different combinations of political efficacy and trust will generate different kinds and intensity of involvement in political activity. This study tests this hypothesis on a broad variety of political activities, while at the same time including the potentially moderating effect of people’s political interest. Using data from a longitudinal study in Sweden (2009-2015), this study shows that different combinations of efficacy-trust do indeed generate distinct patterns of participation for young adults. By adding political interest to the model, the effect of certain efficacy-trust combinations on political participation is present foremost among politically interested citizens. Hence, the hypothesis requires to be complemented by political interest to more accurately understand under which circumstances people engage in various political activities.
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| 19. |
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| 20. |
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