| 1. |
- Hallquist, Mattias, 1969, et al.
(författare)
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Photochemical smog in China: scientific challenges and implications for air-quality policies
- 2016
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Ingår i: National Science Review. - : Oxford University Press (OUP). - 2095-5138 .- 2053-714X. ; 3:4, s. 401-403
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Tidskriftsartikel (refereegranskat)abstract
- In large areas of China severe air pollution events pose a significant threat to human health, ecosystems and climate. Current reduction of primary emissions will also affect secondary pollutants such as ozone (O3) and particulate matter (PM), but the magnitude of the effects is uncertain. Major scientific challenges are related to the formation of O3 and secondary particulate matter including Secondary Organic Aerosols (SOA). Large uncertainties also remain regarding the interactions of soot, SOA and O3 under the influence of different SO2, NOX and VOC concentrations. To improve the understanding of these secondary atmospheric interactions in China, scientific areas of central importance for photochemically induced air pollutants have been identified. In addition to the scientific challenges, results from research need to be synthesized across several disciplines and communicated to stakeholders affected by air pollution and to policy makers responsible for developing abatement strategies. Development of these science-policy interactions can benefit from experience gained under the UN ECE Convention on Long Range Transboundary Air Pollution (LRTAP)
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| 2. |
- Skedung, Lisa, 1980-
(författare)
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Tactile Perception : Role of Friction and Texture
- 2012
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Tactile perception is considered an important contributor to the overall consumer experience of a product. However, what physical properties that create the specifics of tactile perception, are still not completely understood. This thesis has researched how many dimensions that are required to differentiate the surfaces perceptually, and then tried to explain these dimensions in terms of physical properties, by interconnecting human perception measurements with various physical measurements. The tactile perception was assessed by multidimensional scaling or magnitude estimation, in which methods human participants assign numbers to how similar pairs of surfaces are perceived or to the relative quantity of a specified perceptual attribute, such as softness, smoothness, coarseness and coolness. The role of friction and surface texture in tactile perception was investigated in particular detail, because typically tactile exploration involves moving (at least) one finger over a textured surface. A tactile approach for measuring friction was developed by means of moving a finger over the surfaces, mounted on a force sensor. The contribution of finger friction to tactile perception was investigated for surfaces of printing papers and tissue papers, as well as for model surfaces with controlled topography. The overarching research goal of this thesis was to study, systematically, the role of texture in tactile perception of surfaces.The model surfaces displayed a sinusoidal texture with a characteristic wavelength and amplitude, fabricated by surface wrinkling and replica molding techniques. A library of surfaces was manufactured, ranging in wavelengths from 270 nm up to 100 µm and in amplitudes from 7 nm up to 6 µm. These surfaces were rigid and cleanable and could therefore be reused among the participants. To my knowledge, this is the first time in a psychophysical experiment, that the surface texture has been controlled over several orders of magnitude in length scale, without simultaneously changing other material properties of the stimuli.The finger friction coefficient was found to decrease with increasing aspect ratio (amplitude/wavelength) of the model surfaces and also with increasing average surface roughness of the printing papers. Analytical modeling of the finger’s interaction with the model surfaces shows how the friction coefficient increases with the real contact area, and that the friction mechanism is the same on both the nanoscale and microscale. The same interaction mechanism also explains the friction characteristics of tissue paper. Furthermore, it was found that the perceptions of smoothness, coarseness, coolness and dryness are satisfactorily related to the real contact area at the finger-surface interface. It is shown that it is possible to discern perceptually among both printing papers and tissue papers, and this differentiation is based on either two or three underlying dimensions. Rough/smooth and thin/thick were the two main dimensions of surface feel found for the printing papers, whereas friction and wavelength were strongly related to the perceptual cues employed in scaling the model surfaces. These experimental results support the duplex theory of texture perception, which holds that both a “spatial sense”; used to discriminate the roughest textures from the others, and a “vibration sense”; used to discriminate among the smoother textures, are involved. The perception of what is considered rough and smooth depends on the experimental stimulus context. It is concluded that friction is important for human differentiation of surface textures below about 10 µm in surface roughness, and for larger surface textures, friction is less important or can even be neglected.The finger friction experiments also allowed the following conclusions to be drawn: (i) The interindividual variation in friction coefficients is too large to allow direct comparison; however, the trends in relative friction coefficients for a group of participants are the same. (ii) Lipids are transferred to the test surface of study, and this lowers the friction. (iii) Many of the studies point to a characteristic frequency during sliding of about 30 Hz, which is both characteristic of the resonance frequency of skin and the expected frequency associated with the fingerprints. (iv) The applied load in surface interrogation is in fact regulated in response to the friction force.The limits in tactile perception were indirectly researched by similarity scaling experiments on the model surfaces. Wrinkle wavelengths of 760 nm and 870 nm could be discriminated from untextured reference surfaces, whereas 270 nm could not. The amplitude of the wrinkles so discriminated was approximately 10 nm, suggesting that nanotechnology may well have a role to play in haptics and tactile perception.
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| 3. |
- Nimmermark, Anders, 1971
(författare)
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Facets of chemical bonding that enhance or encumber conceptual understanding
- 2014
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Chemical bonding is a vast subject, rich in abstract concepts and advanced and less-advanced explanatory models that the learner has to master. In this context, the teaching of chemical bonding at the secondary school level is extremely important, as it has the potential to increase or hinder students’ further understanding of bonding.In the absence of firm knowledge and effective mental models of chemical bonding, it almost impossible to achieve significant results in any chemical field or application. In this work, which combines the pure chemistry of bonding with didactical studies, I have used database searches, questionnaires, interviews, and textbook analyses to investigate some of the more important aspect of chemical bonding.In the field of pure Science, bond length data have been analysed to ascertain the differences in bond strength between neutral and charged ligands in coordination compounds. While the bond strengths differ, the difference is not sufficiently large for the bonds to be classified as different types.In the didactical field, the conceptual models of students in South Africa and Sweden and underlying causes for these mind-sets, have been investigated. The results show that the different curricula and points of emphasis foster different patterns of understanding of the topic. One finding is that 55%–60% of the students exposed to any of the curricula have a molecular view of a salt that can be traced to visual representations of single ions or formula units of a salt. Therefore, it is important to understand how, when, and which models to use, in order to help students build a more advanced understanding of chemical bonding.
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| 4. |
- Kjellander, Roland, 1948
(författare)
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Att konkretisera det abstrakta: Förstå och undervisa om entropi och temperatur
- 2013
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Ingår i: Modeller, analogier och metaforer i naturvetenskapsundervisning. - Lund : Studentlitteratur. - 9789144090009
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Termodynamik har en viktig plats inom fysik, kemi och många ingenjörsämnen. Ämnet bereder dock ofta konceptuella och andra svårigheter bland annat på grund av sin abstrakta natur. Ett begrepp som vållar särskild huvudbry är entropi. Orsaken till detta är mångfaldig. Entropi är en storhet som inte kan mätas direkt, dess definition är inte enkel och den har egenskaper som kan vara svåra att förstå varför den har. Dessa egenskaper är emellertid av fundamental betydelse bland annat för naturliga processer. Svårigheterna med entropibegreppet finns både då det gäller att själv att förstå det och att lära ut det till andra. I kapitlet beskrivs ett möjligt sätt att närma sig begreppen entropi och temperatur som författaren funnit vara en framgångsrik väg för studenter att ta till sig de väsentligaste grunderna. Dessutom diskuteras, utgående från författarens erfarenhet, varför flera andra alternativ inte är lika lämpliga ur ett naturvetenskapligt perspektiv eller inte lika tillgängliga för studenterna.
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| 5. |
- Bursjöö, Ingela, 1963
(författare)
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SOWING THE SEEDS OF URBAN SCHOOL GARDENS
- 2016
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Ingår i: Eridob, Eleventh Conference of European Researchers in Didactics of Biology.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)
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| 6. |
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| 7. |
- Skedung, Lisa, et al.
(författare)
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Tactile perception : Finger friction, surface roughness and perceived coarseness
- 2011
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Ingår i: Tribology International. - : Elsevier BV. - 0301-679X .- 1879-2464. ; 44:5, s. 505-512
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Tidskriftsartikel (refereegranskat)abstract
- Finger friction measurements performed on a series of printing papers are evaluated to determine representativeness of a single individual. Results show occasionally large variations in friction coefficients. Noteworthy though is that the trends in friction coefficients are the same, where coated (smoother) papers display higher friction coefficients than uncoated (rougher) papers. The present study also examined the relationship between the measured friction coefficients and surface roughness to the perceived coarseness of the papers. It was found that both roughness and finger friction can be related to perceived coarseness, where group data show that perceived coarseness increases with increasing roughness.
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| 8. |
- Airey, John, 1963-, et al.
(författare)
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Making the Invisible Visible : The role of undergraduate textbooks in the teaching and learning of physics and chemistry
- 2023
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Ingår i: Designing futures. - London : UCL Press.
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Konferensbidrag (refereegranskat)abstract
- As disciplines, undergraduate physics and chemistry leverage a particularly wide range of semiotic systems (modes) in order to create and communicate their scientific meanings. Examples of the different semiotic systems employed are: spoken and written language, mathematics, chemical formulae, graphs, diagrams, sketches, computer simulations, hands-on work with experimental apparatus, computer simulations, etc. Individual semiotic resources within this range of semiotic systems are coordinated in specific constellations (Airey & Linder, 2009) in order to mediate scientific knowledge. In this Swedish Research Council project, we are interested in the representation of scientific phenomena that cannot be seen. The question we pose is: How is scientific knowledge mediated when we cannot directly interact with the phenomena in question through our senses? We adopt a social semiotic approach (Airey & Linder, 2017; van Leeuwen, 2005), to investigate the ways in which two phenomena—electromagnetic fields and chemical bonds—are presented in undergraduate textbooks. To do this we carried out a semiotic audit (Airey & Erikson, 2019) of eight textbooks (four in each discipline). We note that the individual resources used have a mixture of affordances—whilst the majority retain high disciplinary affordance, others are unpacked (Patron et al. 2021) providing higher pedagogical affordance. We discuss the ways in which the resources have been combined and orchestrated (Bezemer & Jewitt, 2010) in order to attempt to make visible that which is invisible, and identify a number of potential problems. In earlier work, Volkwyn et al. (2019) demonstrated how experimental work with physics devices can make the Earth’s magnetic field accessible to students through chains of transduction. Thus, we propose that encouraging transductions across the semiotic resource systems provided in textbooks may help students to experience the invisible.ReferencesAirey, J. (2006). Physics students' experiences of the disciplinary discourse encountered in lectures in English and Swedish (Licentiate dissertation, Department of Physics, Uppsala University).Airey, J. (2009). Science, language, and literacy: Case studies of learning in Swedish university physics (Doctoral dissertation, Acta Universitatis Upsaliensis).Airey, J. (2015). Social Semiotics in Higher Education: Examples from teaching and learning in undergraduate physics. In In: SACF Singapore-Sweden Excellence Seminars, Swedish Foundation for International Cooperation in Research in Higher Education (STINT) , 2015 (pp. 103). Airey, J., & Eriksson, U. (2019). Unpacking the Hertzsprung-Russell diagram: A social semiotic analysis of the disciplinary and pedagogical affordances of a central resource in astronomy. Designs for Learning, 11(1), 99-107.Goodwin, C. (2015). Professional vision. In Aufmerksamkeit: Geschichte-Theorie-Empirie (pp. 387-425). Wiesbaden: Springer Fachmedien Wiesbaden.O’Halloran, K. (2007). Mathematical and scientific forms of knowledge: A systemic functional multimodal grammatical approach. language, Knowledge and pedagogy: functional linguistic and sociological perspective, 205-236.Patron, E. (2022). Exploring the role that visual representations play when teaching and learning chemical bonding: An approach built on social semiotics and phenomenography(Doctoral dissertation, Linnaeus University Press).
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