| 11. |
- Baklanov, A. V, et al.
(författare)
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Nanosecond and femtosecond probing of the dynamics of the UV-photodissociation of perfluoroethyliodide C2F5I
- 2001
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Ingår i: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 115:24, s. 11157-11165
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Tidskriftsartikel (refereegranskat)abstract
- The ns photodissociation of perfluoroethyliodide C2F5I at 266 nm has been studied by using the resonant two-photon ionization (R2PI) technique. Recoil anisotropy parameters as well as average translational energy of the I atoms in the fine structure states P-2(1/2) and P-2(3/2) have been determined. The main contribution (99%) to the absorption at 266 nm was found to be caused by a parallel transition to the (3)Q(0) state which gives mainly excited-state atoms I(P-2(1/2)). The ground-state atoms I(P-2(3/2)) were found to appear mainly (88%) from the primarily excited (3)Q(0) state via curve-crossing (3)Q(0)-(1)Q(1) and to a lesser extent (12%) from direct absorption by a perpendicular transition to the (1)Q(1) and (3)Q(1) states. The fs pump-dump technique in combination with ns R2PI probing of the fragments I(P-2(1/2)) and I(P-2(3/2)) and time-of-flight mass spectrometry have been applied to probe the early stage dynamics of the C2F5I molecule on the excited state (3)Q(0) potential energy surface (PES). The evolution time of the excited molecule to the point where the energy gap between the excited state (3)Q(0) and the ground-state potential energy surfaces drops to a value of about 12 440 cm-1 was found to be 52 +/- 13 fs. This time corresponds to about 0.8 Angstrom extension of the C-I bond distance. The molecular dynamics simulation with DFT calculated ground-state PES and (3)Q(0) PES with the shape calculated for methyl iodide found in the literature gives reasonable agreement with the experimental result for the evolution time. (C) 2001 American Institute of Physics.
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| 12. |
- Batani, D., et al.
(författare)
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Effects of laser prepulses on laser-induced proton generation
- 2010
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Ingår i: New Journal of Physics. - : IOP Publishing. - 1367-2630. ; 12
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Tidskriftsartikel (refereegranskat)abstract
- Low-intensity laser prepulses (<10(13) W cm(-2), nanosecond duration) are a major issue in experiments on laser-induced generation of protons, often limiting the performances of proton sources produced by high-intensity lasers (approximate to 10(19) W cm(-2), picosecond or femtosecond duration). Depending on the intensity regime, several effects may be associated with the prepulse, some of which are discussed in this paper: (i) destruction of thin foil targets by the shock generated by the laser prepulse; (ii) creation of preplasma on the target front side affecting laser absorption; (iii) deformation of the target rear side; and (iv) whole displacement of thin foil targets affecting the focusing condition. In particular, we show that under oblique high-intensity irradiation and for low prepulse intensities, the proton beam is directed away from the target normal. Deviation is towards the laser forward direction, with an angle that increases with the level and duration of the ASE pedestal. Also, for a given laser pulse, the beam deviation increases with proton energy. The observations are discussed in terms of target normal sheath acceleration, in combination with a laser-controllable shock wave locally deforming the target surface.
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| 13. |
- Baumann, Stefan, et al.
(författare)
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Gender differences in the diagnostic performance of machine learning coronary CT angiography-derived fractional flow reserve -results from the MACHINE registry
- 2019
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Ingår i: European Journal of Radiology. - : ELSEVIER IRELAND LTD. - 0720-048X .- 1872-7727. ; 119
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: This study investigated the impact of gender differences on the diagnostic performance of machine-learning based coronary CT angiography (cCTA)-derived fractional flow reserve (CT-FFR mL ) for the detection of lesion-specific ischemia. Method: Five centers enrolled 351 patients (73.5% male) with 525 vessels in the MACHINE (Machine leArning Based CT angiograpHy derIved FFR: a Multi-ceNtEr) registry. CT-FFRML and invasive FFR amp;lt;= 0.80 were considered hemodynamically significant, whereas cCTA luminal stenosis amp;gt;= 50% was considered obstructive. The diagnostic performance to assess lesion-specific ischemia in both men and women was assessed on a per-vessel basis. Results: In total, 398 vessels in men and 127 vessels in women were included. Compared to invasive FFR, CT-FFRML reached a sensitivity, specificity, positive predictive value, and negative predictive value of 78% (95%CI 72-84), 79% (95%CI 73-84), 75% (95%CI 69-79), and 82% (95%CI: 76-86) in men vs. 75% (95%CI 58-88), 81 (95%CI 72-89), 61% (95%CI 50-72) and 89% (95%CI 82-94) in women, respectively. CT-FFRML showed no statistically significant difference in the area under the receiver-operating characteristic curve (AUC) in men vs. women (AUC: 0.83 [95%CI 0.79-0.87] vs. 0.83 [95%CI 0.75-0.89], p = 0.89). CT-FFRML was not superior to cCTA alone [AUC: 0.83 (95%CI: 0.75-0.89) vs. 0.74 (95%CI: 0.65-0.81), p = 0.12] in women, but showed a statistically significant improvement in men [0.83 (95%CI: 0.79-0.87) vs. 0.76 (95%CI: 0.71-0.80), p = 0.007]. Conclusions: Machine-learning based CT-FFR performs equally in men and women with superior diagnostic performance over cCTA alone for the detection of lesion-specific ischemia.
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| 14. |
- Behravesh, Maysam, et al.
(författare)
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Why Israel Won’t Abide Any Iran Nuclear Accord
- 2013
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Ingår i: Foreign Policy In Focus (FPIF), Institute for Policy Studies (IPS). - 1524-1939.
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Tidskriftsartikel (populärvet., debatt m.m.)abstract
- Any diplomatic resolution of Iran’s nuclear controversy will deprive Israeli hawks of what they see as the sole feasible justification to overthrow the Iranian regime by military force.
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| 15. |
- Behrens, Jane W., et al.
(författare)
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Personality- and size-related metabolic performance in invasive round goby (Neogobius melanostomus)
- 2020
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Ingår i: Physiology and Behavior. - : Elsevier. - 0031-9384 .- 1873-507X. ; 215, s. 1-6
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Tidskriftsartikel (refereegranskat)abstract
- Differences between individuals in behavioral type (i.e. animal personality) are ecologically and evolutionarily important because they can have significant effects on fitness components such as growth and predation risk. In the present study we are used the invasive round goby (Neogobius melanostomus) from an established population in controlled experiments to examine the relationships among personality, metabolic performance, and growth rate (inferred as size-at-age). Boldness was measured as the time to return to normal behavior after a simulated predator attack, where fish with shorter freezing times were categorized as "bold" and fish with longer times were categorized as "shy." We show that bold fish have significantly higher standard metabolic rate (SMR) than their shy conspecifics, whereas there was no difference between personality types in their maximum metabolic rate (MMR) or aerobic scope (AS). Bold fish furthermore had a smaller size-at-age as compared to shy fish. Together this provides evidence of a metabolic underpinning of personality where the high-SMR bold fish require more resources to sustain basic life functions than their low-SMR shy conspecifics, indicating that bold round goby from established populations with high densities (and high competition for food) pay a price of reduced growth rate.
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| 16. |
- Berg, Mikael, Universitetslektor, 1970-, et al.
(författare)
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Att resonera nyanserat i Samhällskunskap : ett begränsande eller vidgande kunskapskrav?
- 2020
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Ingår i: SO-didaktik. - : Föreningen SO-didaktik. - 2002-4525. ; :9, s. 70-75
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Många samhällskunskapslärare har nog funderat på hur man som lärare ska ta sig an och agera gentemot elever som ger uttryck för ett ensidigt politiskt perspektiv. Hur ska man få eleven att vidga sina perspektiv utan att för den skull styra och bestämma för eleven vad som ”rätt sak att tänka och säga”? Läraren måste samtidigt förhålla sig till skolans värdegrund och demokratiska uppdrag. Forskarna Mikael Berg och Anders Persson har undersökt hur samhällskunskapslärare skulle agera i ett fingerat scenario kring en sådan ”vinklad” elev och de upptänkte då att lärarna var ganska överens om att det handlar om att ge eleven fler perspektiv, men hur elever skulle få dessa perspektiv varierade.
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| 17. |
- Berg, Mikael, Universitetslektor, 1970-, et al.
(författare)
-
Graderande granskning och förklarade glapp : Svensk historie- och samhällskunskapsdidaktisk forskning om lärares bedömningspraktik 2009–2019
- 2020
-
Ingår i: Nordidactica. - Karlstad : CSD Karlstad. - 2000-9879. ; :1, s. 18-44
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Tidskriftsartikel (refereegranskat)abstract
- During the last decade there has been an increasing interest in the Swedish research field concerning assessment in schools, especially with focus on the school subject’s history and social science. The aim of this article is therefore to explore what perspectives that have being used by researchers in the Swedish field of history and social science subject didactic, when investigating teacher’s assessment practice. The method used in the article is a text analysis of 13 Swedish thesis and articles that deal with teacher’s assessment practice within the Swedish field of history and social science subject didactics between 2009 and 2019. The result shows that there an overwhelming part of the studies deals with examine teacher’s assessment practice. Another dominant trend is to explain the variations in teacher’s assessment practice. Overall the result shows that there is a lack of studies which begin with teachers subject specific experiences and also a lack of studies with a policy critical approach. To try to capture the complexity in assessment we therefore argue in the light of the result that there is a need of both a theoretical and cumulative broadening of the Swedish research field concerning teacher’s assessment with focus on the school subject’s history and social science.
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| 18. |
- Berg, Mikael, Universitetslektor, 1970-, et al.
(författare)
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The Didactic Function of Narratives : Teacher discussions on the use of challenging, engaging, unifying, and complementing narratives in the history classroom
- 2023
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Ingår i: Historical Encounters. - : HERMES History Education Research Network. - 2203-7543. ; 10:1, s. 44-59
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Tidskriftsartikel (refereegranskat)abstract
- At a time when society is characterised by a polarised social climate, it is teachers who need to contribute to a nuanced orientation of the world. This article looks at the ways historical narratives can be used as a collective didactic resource in the historical-cultural context of contemporary society. Its purpose is to analyse the didactic function that underlies historical narratives in relation to students’ understanding of society. Our study builds on three focus group interviews with six upper-secondary-school teachers of history and social studies. The method used is the stimulated-recall interview whereby teachers talk about various teaching situations. Four uses of historical narratives were identified, each with its own didactic function. The first is the use of the “challenging” narrative, the function of which is to disrupt and realign students’ understanding of society. The second is the use of the “engaging” narrative: its function is to involve and activate students in their present understanding of society. The third is the use of the “unifying” narrative, the function of which is to bridge contradictions within society. The fourth and final narrative is the “complementing” narrative, whose function it is to broaden and open students’ understanding of society. To address students in terms of their present understanding of society, teachers employ these four narratives as didactic resources. In such a way, these uses of historical narratives tie in with the teachers’ overall aim to contribute an alternative perspective to students’ current understanding of society.As such, the results reveal the general theoretical knowledge teachers have relating to their profession.
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| 19. |
- Berglund, Martin, 1985-, et al.
(författare)
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Evaluation of a microplasma source based on a stripline split-ring resonator
- 2013
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Ingår i: Plasma sources science & technology. - : Institute of Physics (IOP). - 0963-0252 .- 1361-6595. ; 22:5, s. 055017-
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, a stripline split-ring resonator microwave-induced plasma source, aimed for integration in complex systems, is presented and compared with a traditional microstrip design. Devices based on the two designs are evaluated using a plasma breakdown test setup for measuring the power required to ignite plasmas at different pressures. Moreover, the radiation efficiency of the devices is investigated with a Wheeler cap, and their electromagnetic compatibility is investigated in a variable electrical environment emulating an application. Finally, the basic properties of the plasma in the two designs are investigated in terms of electron temperature, plasma potential and ion density. The study shows that, with a minor increase in plasma ignition power, the stripline design provides a more isolated and easy-to-integrate alternative to the conventional microstrip design. Moreover, the stripline devices showed a decreased antenna efficiency as compared with their microstrip counterparts, which is beneficial for plasma sources. Furthermore, the investigated stripline devices exhibited virtually no frequency shift in a varying electromagnetic environment, whereas the resonance frequency of their microstrip counterparts shifted up to 17.5%. With regard to the plasma parameters, the different designs showed only minor differences in electron temperature, whereas the ion density was higher with the stripline design.
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| 20. |
- Berglund, Martin, 1985-, et al.
(författare)
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Evaluation of dielectric properties of HTCC alumina for realization of plasma sources
- 2015
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Ingår i: Journal of Electronic Materials. - : Springer Science and Business Media LLC. - 0361-5235 .- 1543-186X. ; 44:10, s. 3654-3660
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Tidskriftsartikel (refereegranskat)abstract
- As the sensitivity of optogalvanic spectroscopy based on prototype microplasma sources increases, contamination from composite materials in the printed circuit board used starts to become a concern. In this paper, a transfer to high-temperature cofired alumina and platinum is made and evaluated. The high-purity alumina provides an inert plasma environment, and allows for temperatures above 1000A degrees C, which is beneficial for future integration of a combustor. To facilitate the design of high-end plasma sources, characterization of the radio frequency (RF) parameters of the materials around 2.6 GHz is carried out. A RF resonator structure was fabricated in both microstrip and stripline configurations. These resonators were geometrically and electrically characterized, and epsilon (r) and tan were calculated using the RF waveguide design tool Wcalc. The resulting epsilon (r) for the microstrip and stripline was found to be 10.68 (+/- 0.12) and 9.65 (+/- 0.14), respectively. The average tan of all devices was found to be 0.0011 (+/- 0.0007). With these parameters, a series of proof-of-concept plasma sources were fabricated and evaluated. Some problems in the fabrication stemmed from the lamination and difficulties with the screen-printing, but a functioning plasma source was demonstrated.
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