| 1. |
- van Meeningen, Ylva
(författare)
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Is genetic diversity more important for terpene emissions than latitudinal adaptation? : Using genetically identical trees to better understand emission fluctuations across a European gradient
- 2017
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Biogenic volatile organic compounds (BVOCs) are trace gases other than CO2 and CH4 produced and emitted by the vegetation. The group consists of thousands of compounds in various shapes and sizes and with short atmospheric lifetimes. Some of the most common BVOC groups are called isoprene, monoterpenes and sesquiterpenes. For the plant, the emission of BVOCs is used for plant communication, attracting pollinators, to deter herbivores and to enhance abiotic stress defense against for example high temperatures, irradiation or oxidative stresses. But once released into the atmosphere, they are affecting the atmospheric chemistry which in effect alters our climate. Depending on the atmospheric composition, BVOC emissions can either enhance tropospheric ozone and indirectly prolong the lifetimes of greenhouse gases such as methane by reducing the concentration of hydroxyl radicals, or increase the formation of aerosols and cloud condensation nuclei which may mitigate the effect of greenhouse gases on global warming.It is fairly well known that BVOCs have an impact on the climate. However, whether the BVOC emissions have a warming or cooling effect on the overall climate is difficult to determine due to existing emission pattern variations both between individuals of the same species and between species. Some of the reasons which are often discussed to be influential and where there is relatively little data available are within-species genetic variation, stress response, adaptation to different weather and climatic conditions and seasonality. In this thesis, focus has been given to the importance of genetic diversity and adaptation to different growing conditions. Studies have been conducted on three European tree species with genetically identical individuals across a latitudinal gradient, stretching from Slovenia to southern Finland. The main results were that even though the emission amounts varied between sites due to differences in weather events, the progression of the growing season and insect outbreaks, the compound composition between individuals were similar both across latitudes and between measurement years. By showing compound composition stability for genetically identical trees, the results highlights the importance of taking genetic diversity into account in terms of observed emission pattern variations. The response to changing light conditions on the emission amount of different compounds was also investigated. The results uncovered that different compounds had different emission responses to changing light conditions, but that the response of the compounds were fairly similar across different species.
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| 2. |
- van der Wijngaart, Wouter, et al.
(författare)
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A low-temperature thermopneumatic actuation principle for gas bubble microvalves
- 2007
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Ingår i: Journal of microelectromechanical systems. - : IEEE Press. - 1057-7157 .- 1941-0158. ; 16:3, s. 765-774
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Tidskriftsartikel (refereegranskat)abstract
- We introduce a novel type of microfluidic actuator in which a trapped air bubble functions as the thermally controlled volume displacing element. The pressure of the trapped air pocket is controlled by the changing equilibrium gas composition for static operation and by thermal expansion for dynamic operation. The volume displacement is determined by the liquid surface tension and the valve geometry. A fully functional demonstrator device was successfully fabricated and tested. The absence of moving mechanical parts, the electrical control of the valve, and the limited required actuation temperature make the actuator suitable for control of large-scale integration fluidic networking in biotechnical applications.
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| 3. |
- Botsis, Hannah
(författare)
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Subjectivity, Language and the Postcolonial : Beyond Bourdieu in South Africa
- 2017
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Bok (refereegranskat)abstract
- In Subjectivity, Language and the Postcolonial, Hannah Botsis draws on theoretical work that exists at the intersection of critical social psychology, sociolinguistics and the political economy of language, to examine the relationships between language, subjectivity, materiality and political context.The book foregrounds the ways in which the work of Bourdieu could be read in conjunction with ‘poststructural’ theorists such as Butler and Derrida to offer a critical understanding of subjectivity, language and power in postcolonial contexts. This critical engagement with theorists traditionally from outside of psychology allows for a situated approach to understanding the embodied and symbolic possibilities and constraints for the postcolonial subject. This exploration opens up how micro-politics of power are refracted through ideological categories such as language, race and class in post-apartheid South Africa.Also drawing on the empirical findings of original research undertaken in the South African context on students’ linguistic biographies, the book offers a unique perspective – critical social theory is brought to bear on the empirical linguistic biographies of postcolonial subjects, offering insight into how power is negotiated in the postcolonial symbolic economy.Ideal for advanced undergraduate and postgraduate students on courses including social psychology, sociolinguistics, sociology, politics, and education, this is an invaluable resource for students and researchers alike.
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| 4. |
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| 5. |
- Diehl, Roland, et al.
(författare)
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Early Ni-56 decay gamma rays from SN2014J suggest an unusual explosion
- 2014
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Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 345:6201, s. 1162-1165
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Tidskriftsartikel (refereegranskat)abstract
- Type Ia supernovae result from binary systems that include a carbon-oxygen white dwarf, and these thermonuclear explosions typically produce 0.5 solar mass of radioactive Ni-56. The Ni-56 is commonly believed to be buried deeply in the expanding supernova cloud. In SN2014J, we detected the lines at 158 and 812 kiloelectron volts from Ni-56 decay (time similar to 8.8 days) earlier than the expected several-week time scale, only similar to 20 days after the explosion and with flux levels corresponding to roughly 10% of the total expected amount of Ni-56. Some mechanism must break the spherical symmetry of the supernova and at the same time create a major amount of Ni-56 at the outskirts. A plausible explanation is that a belt of helium from the companion star is accreted by the white dwarf, where this material explodes and then triggers the supernova event.
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| 6. |
- Sundberg, Marcus
(författare)
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Regional Ekonomi
- 2011
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Konferensbidrag (refereegranskat)
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| 7. |
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| 8. |
- van der Wijngaart, Wouter, et al.
(författare)
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A micromachined interface for transfer of liquid or vapour sample to a liquid solution
- 2005
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Ingår i: Solid-State Sensors, Actuators and Microsystems, 2005. Digest of Technical Papers. TRANSDUCERS '05. The 13th International Conference on (Volume:2 ). - NEW YORK : IEEE conference proceedings. - 0780389948 ; , s. 1276-1279
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Konferensbidrag (refereegranskat)abstract
- A novel microfluidic interface for vapour-to-liquid adsorption and droplet-to-liquid transfer was designed and fabricated using silicon micromachining. The interface was characterised and successfully tested.
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| 9. |
- Van Meeningen, Ylva, et al.
(författare)
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Isoprenoid emission response to changing light conditions of English oak, European beech and Norway spruce
- 2017
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Ingår i: Biogeosciences. - : Copernicus GmbH. - 1726-4170 .- 1726-4189. ; 14:18, s. 4045-4060
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Tidskriftsartikel (refereegranskat)abstract
- Light is an important environmental factor controlling biogenic volatile organic compound (BVOC) emissions, but in natural conditions its impact is hard to separate from other influential factors such as temperature. We studied the light response of foliar BVOC emissions, photosynthesis and stomatal conductance on three common European tree species, namely English oak (Quercus robur), European beech (Fagus sylvatica) and two provenances of Norway spruce (Picea abies) in Taastrup, Denmark. Leaf scale measurements were performed on the lowest positioned branches of the tree in July 2015. Light intensity was increased in four steps (0, 500, 1000 and 1500 ?molm2 s-1), whilst other chamber conditions such as temperature, humidity and CO2 levels were fixed. Whereas the emission rate differed between individuals of the same species, the relative contributions of compounds to the total isoprenoid emission remained similar. Whilst some compounds were species specific, the compounds -pinene, camphene, 3-carene, limonene and eucalyptol were emitted by all of the measured tree species. Some compounds, like isoprene and sabinene, showed an increasing emission response with increasing light intensity, whereas other compounds, like camphene, had no significant emission response to light for most of the measured trees. English oak and European beech showed high light-dependent emission fractions from isoprene and sabinene, but other emitted compounds were light independent. For the two provenances of Norway spruce, the compounds -pinene, 3-carene and eucalyptol showed high light-dependent fractions for many of the measured trees. This study highlights differences between compound emissions in their response to a change in light and a possible light independence for certain compounds, which might be valid for a wider range of tree species. This information could be of importance when improving emission models and to further emphasize the discussion regarding light or temperature dependencies for individual compounds across species. Light is an important environmental factor controlling biogenic volatile organic compound (BVOC) emissions, but in natural conditions its impact is hard to separate from other influential factors such as temperature. We studied the light response of foliar BVOC emissions, photosynthesis and stomatal conductance on three common European tree species, namely English oak (Quercus robur), European beech (Fagus sylvatica) and two provenances of Norway spruce (Picea abies) in Taastrup, Denmark. Leaf scale measurements were performed on the lowest positioned branches of the tree in July 2015. Light intensity was increased in four steps (0, 500, 1000 and 1500 ?molm-2 s-1), whilst other chamber conditions such as temperature, humidity and CO2 levels were fixed. Whereas the emission rate differed between individuals of the same species, the relative contributions of compounds to the total isoprenoid emission remained similar. Whilst some compounds were species specific, the compounds -pinene, camphene, 3-carene, limonene and eucalyptol were emitted by all of the measured tree species. Some compounds, like isoprene and sabinene, showed an increasing emission response with increasing light intensity, whereas other compounds, like camphene, had no significant emission response to light for most of the measured trees. English oak and European beech showed high light-dependent emission fractions from isoprene and sabinene, but other emitted compounds were light independent. For the two provenances of Norway spruce, the compounds -pinene, 3-carene and eucalyptol showed high light-dependent fractions for many of the measured trees. This study highlights differences between compound emissions in their response to a change in light and a possible light independence for certain compounds, which might be valid for a wider range of tree species. This information could be of importance when improving emission models and to further emphasize the discussion regarding light or temperature dependencies for individual compounds across species. Light is an important environmental factor controlling biogenic volatile organic compound (BVOC) emissions, but in natural conditions its impact is hard to separate from other influential factors such as temperature. We studied the light response of foliar BVOC emissions, photosynthesis and stomatal conductance on three common European tree species, namely English oak (Quercus robur), European beech (Fagus sylvatica) and two provenances of Norway spruce (Picea abies) in Taastrup, Denmark. Leaf scale measurements were performed on the lowest positioned branches of the tree in July 2015. Light intensity was increased in four steps (0, 500, 1000 and 1500 ?molm-2, s-1), whilst other chamber conditions such as temperature, humidity and CO2, levels were fixed. Whereas the emission rate differed between individuals of the same species, the relative contributions of compounds to the total isoprenoid emission remained similar. Whilst some compounds were species specific, the compounds -pinene, camphene, 3-carene, limonene and eucalyptol were emitted by all of the measured tree species. Some compounds, like isoprene and sabinene, showed an increasing emission response with increasing light intensity, whereas other compounds, like camphene, had no significant emission response to light for most of the measured trees. English oak and European beech showed high light-dependent emission fractions from isoprene and sabinene, but other emitted compounds were light independent. For the two provenances of Norway spruce, the compounds -pinene, 3-carene and eucalyptol showed high light-dependent fractions for many of the measured trees. This study highlights differences between compound emissions in their response to a change in light and a possible light independence for certain compounds, which might be valid for a wider range of tree species. This information could be of importance when improving emission models and to further emphasize the discussion regarding light or temperature dependencies for individual compounds across species.
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