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  • 1167951. Yuzvyuk, M. H.
    et al.
    Putrolaynen, V. V.
    Grishin, Alexander M.
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Processing of ultra-hard coatings based on AlMgB14 films2016In: 18th International Conference PhysicA.SPb26–29 October 2015, Saint Petersburg, Russian Federation, Institute of Physics Publishing (IOPP), 2016, Vol. 769, no 1, article id 012039Conference paper (Refereed)
    Abstract [en]

    First time AlMgB14 films were prepared in Ames Lab by pulsed laser deposition technique. In this work, RF magnetron sputtering from a single stoichiometric target was employed to fabricate hard AlMgB14 coatings on Si wafer and industrial items. Measurements of nanohardness and elastic Young's modulus were performed to determine reliable strength characteristics of samples. Smooth 3 μm thick AlMgB14 films with the RMS surface roughness to be less than 1 nm exhibit hardness of 34 GPa and modulus of elasticity of 230 GPa at 20 mN peak load.

  • 1167952. Yvdal, Isabell
    Historieundervisningen i det mångkulturella klassrummet: Lärares strategier för att utveckla elevers historiemedvetande2013Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Abstract

    This essay examines the points of elementary teachers use in their history in the multicultural classroom. A further aim is to examine how teachers perceive historical consciousness and how they work to develop students' historical consciousness. I have immersed in previous research, to find out what is meant by multicultural and definition of historical consciousness. In order to find answers to my purpose, I conducted interviews with six teachers working in multicultural schools. The previous research shows that the Western cultural heritage is the norm in the Swedish history lessons, despite that the Swedish curriculum writes that the individual should be in focus.

    The results of the survey show that Swedish history dominates in history teaching and according to some of the teachers, this is based on it's Swedish and Nordic history as part of the knowledge that students must achieve in middle school. Despite this, there are some teachers through various approaches involving all students and adjust instruction based on the multicultural perspective. Some of the teachers are editing texts to make them easier to read and some teachers connect to students' home countries and make different comparisons. To develop a sense of history, teachers let students imagine what it looked like 100 years ago and also how it might look in the future, how traditions could be linked to the past could take place. In some cases, the teachers were native speakers in parallel with the regular teaching, helping the students with their own native history.

     

    Keywords: Historical consciousness, multicultural, intercultural education, history teaching

  • 1167953.
    Yveborg, Moa
    KTH, School of Engineering Sciences (SCI), Physics, Physics of Medical Imaging.
    Quantification and Maximization of Performance Measures for Photon Counting Spectral Computed Tomography2015Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    During my time as a PhD student at the Physics of Medical Imaging group at KTH, I have taken part in the work of developing a photon counting spectrally resolved silicon detector for clinical computed tomography. This work has largely motivated the direction of my research, and is the main reason for my focus on certain issues. Early in the work, a need to quantify and optimize the performance of a spectrally resolved detector was identified. A large part of my work have thus consisted of reviewing conventional methods used for performance quantification and optimization in computed tomography, and identifying which are best suited for the characterization of a spectrally resolved system. In addition, my work has included comparisons of conventional systems with the detector we are developing. The collected result after a little more than four years of work are four publications and three conference papers.

    This compilation thesis consists of five introductory chapters and my four publications. The introductory chapters are not self-contained in the sense that the theory and results from all my published work are included. Rather, they are written with the purpose of being a context in which the papers should be read.

    The first two chapters treat the general purpose of the introductory chapters, and the theory of computed tomography including the distinction between conventional, non-spectral, computed tomography, and different practical implementations of spectral computed tomography. The second chapter consists of a review of the conventional methods developed for quantification and optimization of image quality in terms of detectability and signal-to-noise ratio, part of which are included in my published work. In addition, the theory on which the method of material basis decomposition is based on is presented, together with a condensed version of the results from my work on the comparison of two systems with fundamentally different practical solutions for material quantification. In the fourth chapter, previously unpublished measurements on the photon counting spectrally resolved detector we are developing are presented, and compared to Monte Carlo simulations. In the fifth and final chapter, a summary of the appended publications is included.

  • 1167954.
    Yveborg, Moa
    et al.
    KTH, School of Engineering Sciences (SCI), Physics, Medical Imaging.
    Danielsson, Mats
    KTH, School of Engineering Sciences (SCI), Physics, Medical Imaging.
    Bornefalk, Hans
    KTH, School of Engineering Sciences (SCI), Physics, Medical Imaging.
    Performance evaluation of a sub-millimetre spectrally resolved CT system on high- and low-frequency imaging tasks: a simulation2012In: Physics in Medicine and Biology, ISSN 0031-9155, E-ISSN 1361-6560, Vol. 57, no 8, p. 2373-2391Article in journal (Refereed)
    Abstract [en]

    We are developing a photon-counting silicon strip detector with 0.4 x 0.5 mm(2) detector elements for clinical CT applications. Except for the limited detection efficiency of approximately 0.8 for a spectrum of 80 kVp, the largest discrepancies from ideal spectral behaviour have been shown to be Compton interactions in the detector and electronic noise. Using the framework of cascaded system analysis, we reconstruct the 3D MTF and NPS of a silicon strip detector including the influence of scatter and charge sharing inside the detector. We compare the reconstructed noise and signal characteristics with a reconstructed 3D MTF and NPS of an ideal energy-integrating detector system with unity detection efficiency, no scatter or charge sharing inside the detector, unity presampling MTF and 1 x 1 mm(2) detector elements. The comparison is done by calculating the dose-normalized detectability index for some clinically relevant imaging tasks and spectra. This work demonstrates that although the detection efficiency of the silicon detector rapidly drops for the acceleration voltages encountered in clinical computed tomography practice, and despite the high fraction of Compton interactions due to the low atomic number, silicon detectors can perform on a par with ideal energy-integrating detectors for routine imaging tasks containing low-frequency components. For imaging tasks containing high-frequency components, the proposed silicon detector system can perform approximately 1.1-1.3 times better than a fully ideal energy-integrating system.

  • 1167955.
    Yveborg, Moa
    et al.
    KTH, School of Engineering Sciences (SCI), Physics, Medical Imaging.
    Danielsson, Mats
    KTH, School of Engineering Sciences (SCI), Physics, Medical Imaging.
    Bornefalk, Hans
    KTH, School of Engineering Sciences (SCI), Physics, Medical Imaging.
    Task based weights for spectral computed tomography2012In: Progress in Biomedical Optics and Imaging - Proceedings of SPIE, SPIE - International Society for Optical Engineering, 2012, Vol. 8313, p. 831334-Conference paper (Refereed)
    Abstract [en]

    In photon counting multi-bin CT, both projection based weighting and image based weighting (designed to maximize the signal-difference-to-noise ratio SDNR) in the final image, are pixel based and do not account for any spatial frequency dependency of signal and noise among the bins. The same weighting scheme will be used when imaging objects with a large fraction of high spatial frequencies and those with predominantly low spatial frequency content. Any effect on the detectability of a certain target due to correlation between detector elements and bins that might arise in pulse height discriminating systems will not be captured using such an approach. We show how to take the spatial frequency dependency of signal and noise transfer for each bin, and the spatial frequency composition of a target, into account when determining optimal task based weights for photon-counting multi-bin CT imaging using the 2D slice detectability index by applying cascaded system analysis to a spectrally resolved photon counting CT detector system with multiple bins.

  • 1167956.
    Yveborg, Moa
    et al.
    KTH, School of Engineering Sciences (SCI), Physics, Physics of Medical Imaging.
    Danielsson, Mats
    KTH, School of Engineering Sciences (SCI), Physics, Physics of Medical Imaging.
    Bornefalk, Hans
    KTH, School of Engineering Sciences (SCI), Physics, Physics of Medical Imaging.
    Theoretical comparison of a dual energy system and photon counting silicon detector used for material quantification in spectral CT2015In: IEEE Transactions on Medical Imaging, ISSN 0278-0062, E-ISSN 1558-254X, Vol. 34, no 3, p. 796-806Article in journal (Refereed)
    Abstract [en]

    Any method using dual energy computed tomography (CT) has to make prior assumptions in order to quantify k-edge contrast agents. This work estimates the mean square error (MSE) in contrast agent quantification employing a method based on assigning each reconstructed voxel a ratio of soft tissue and fat using dual energy CT. The results are compared to the MSE using a photon counting silicon detector with multiple bins. The square root of the MSEs of the quantifications of iodine and gadolinium for an object consisting of soft tissue and fat using the silicon detector and dual energy CT range from below 2% and 1% of the contrast agent content for 100 ${rm mg}/{rm cm}^{3}$ of iodine and gadolinium, up to approximately 10% and 13%, and 6% and 4%, for 5 ${rm mg}/{rm cm}^{3}$ of iodine and gadolinium, respectively. When adding bone with a voxel volume fraction of 2.2%, the square root of the MSEs of the quantifications of iodine and gadolinium using dual energy CT increases to 25% and 6%, respectively, for 5 ${rm mg}/{rm cm}^{3}$ of contrast agent. In conclusion, results indicate that the noise levels of the material quantification using the silicon detector are higher than the noise levels using a dual energy CT when the composition of the object is known. However, using a dual energy CT increases the risk of model specification error and subsequently a large bias in contrast agent quantification, a problem which does not exist when using a multi-bin CT where the number of energy bins is larger than two.

  • 1167957.
    Yveborg, Moa
    et al.
    KTH, School of Engineering Sciences (SCI), Physics, Medical Imaging.
    Danielsson, Mats E.
    KTH, School of Engineering Sciences (SCI), Physics, Medical Imaging.
    Bornefalk, Hans
    KTH, School of Engineering Sciences (SCI), Physics, Medical Imaging.
    Performance evaluation of a sub-millimeter spectrally resolved CT system on pediatric imaging tasks: a simulation2011In: MEDICAL IMAGING 2011: PHYSICS OF MEDICAL IMAGING / [ed] Pelc, NJ; Samei, E; Nishikawa, RM, 2011, Vol. 7961Conference paper (Refereed)
    Abstract [en]

    We are developing a photon counting silicon strip detector with 0.4x0.5 mm(2) square detector elements for clinical CT applications. Except the somewhat limited detection efficiency at higher kVp's the largest discrepancies from ideal spectral behavior have been shown to be Compton interactions in the detector combined with electronic noise. Using the framework of cascaded systems analysis, we reconstruct the 3D MTF and NPS of a silicon strip detector using "optimal" projection based weighting, including the influence of scatter and charge sharing inside the detector. We compare the reconstructed noise and signal characteristics with a reconstructed 3D MTF and NPS of an ideal energy integrating detector by calculating the detectability index for several clinically relevant imaging task. This work demonstrates that although the detection efficiency of the silicon detector rapidly drops for the acceleration voltages encountered in clinical computed tomography practice and the high fraction of Compton interactions due to the low atomic number, silicon detectors can perform on par with ideal energy integrating detectors for routine imaging tasks contaning low frequency components. For imaging task containing high frequency components, silicon detectors can perform approximately 1.4 - 1.8 times better than a fully ideal energy integrating system with unity detection, no scatter or charge sharing inside the detector and 1x1 mm(2) square detector elements.

  • 1167958.
    Yveborg, Moa
    et al.
    KTH, School of Engineering Sciences (SCI), Physics, Physics of Medical Imaging.
    Hans, Bornefalk
    KTH, School of Engineering Sciences (SCI), Physics, Physics of Medical Imaging.
    Mats, Persson
    KTH, School of Engineering Sciences (SCI), Physics, Physics of Medical Imaging.
    Optimal frequency-based weighting for spectral x-ray projection imaging2015In: IEEE Transactions on Medical Imaging, ISSN 0278-0062, E-ISSN 1558-254X, Vol. 34, no 3, p. 779-787Article in journal (Refereed)
    Abstract [en]

    The purpose of this work is to derive a weighting scheme that maximizes the frequency-dependent ideal observer signal-difference-to-noise ratio, commonly referred to as detectability index or Hotelling-SDNR, for spectral X-ray projection imaging. Starting from basic statistical decision theory, optimal frequency-dependent weights are derived for a multiple-bin system and the Hotelling-SDNR calculated. A 28% increase in detectability index is found for high frequency objects when applying optimal frequency-dependent weights instead of pixel-based weights to a simplified model of a silicon detector, decreasing towards 0% for low frequency objects. Simulation results indicate a potentially large increase in detectability for high-frequency object imaging using silicon detectors, thus meriting further evaluations on a real system.

  • 1167959.
    Yveborg, Moa
    et al.
    KTH, School of Engineering Sciences (SCI), Physics, Medical Imaging.
    Persson, Mats
    KTH, School of Engineering Sciences (SCI), Physics, Medical Imaging.
    Crafoord, Joakim
    Danielsson, Mats
    KTH, School of Engineering Sciences (SCI), Physics, Medical Imaging.
    Bornefalk, Hans
    KTH, School of Engineering Sciences (SCI), Physics, Medical Imaging.
    Eliminated risk of iodine contrast cancellation with multibin spectral CT2013In: Physics in Medicine and Biology, ISSN 0031-9155, E-ISSN 1361-6560, Vol. 58, no 14, p. N201-N209Article in journal (Refereed)
    Abstract [en]

    This note compares the extent of contrast cancellation induced by iodinated contrast agents in energy integrating and photon counting multibin CT images. The contrast between a hypodense target and soft tissue is modeled for the two systems for a range of iodine concentrations and tube voltages. In energy integrating systems, we show that the contrast vanishes for low concentrations of iodine whereas the same effect is not seen in multibin systems. We conclude that it is the ability of multibin systems to apply weighting schemes post-acquisition that allows the operator to eliminate the risk of contrast cancellation between iodinated targets and the background.

  • 1167960.
    Yveborg, Moa
    et al.
    KTH, School of Engineering Sciences (SCI), Physics, Physics of Medical Imaging.
    Xu, Cheng
    KTH, School of Engineering Sciences (SCI), Physics, Physics of Medical Imaging.
    Fredenberg, Erik
    KTH, School of Engineering Sciences (SCI), Physics, Physics of Medical Imaging.
    Danielsson, Mats
    KTH, School of Engineering Sciences (SCI), Physics, Physics of Medical Imaging.
    Photon-counting CT with silicon detectors: feasibility for pediatric imaging2009In: Medical Imaging 2009: Physics of Medical Imaging, 2009, Vol. 7258Conference paper (Refereed)
    Abstract [en]

    X-ray detectors made of crystalline silicon have several advantages including low dark currents, fast charge collection and high energy resolution. For high-energy x-rays, however, silicon suffers from its low atomic number, which might result in low detection efficiency, as well as low energy and spatial resolution due to Compton scattering. We have used a monte-carlo model to investigate the feasibility of a detector for pediatric CT with 30 to 40 mm of silicon using x-ray spectra ranging from 80 to 140 kVp. A detection efficiency of 0.74 was found at 80 kVp, provided the noise threshold could be set low. Scattered photons were efficiently blocked by a thin metal shielding between the detector units, and Compton scattering in the detector could be well separated from photo absorption at 80 kVp. Hence, the detector is feasible at low acceleration voltages, which is also suitable for pediatric imaging. We conclude that silicon detectors may be an alternative to other designs for this special case.

  • 1167961.
    Yveborg, Zandra
    et al.
    Dalarna University, School of Technology and Business Studies, Graphic/Arts Technology.
    Isaksson, Erik
    Dalarna University, School of Technology and Business Studies, Graphic/Arts Technology.
    Kundnytta med JDF-flöde2006Independent thesis Basic level (degree of Bachelor)Student thesis
    Abstract [sv]

    Examensarbetet har gjorts utifrån Företaget AB där kundnyttan med JDF har utretts. Rapporten presenterar de för- och nackdelar med JDF-flöde som framkommit under projektets gång. Man kan välja att utnyttja JDF på olika sätt. I rapporten har tre hypoteser ställts mot varandra där utnyttjandegraden av JDF kontra för- och nackdelar för kunder och tryckeri presenterats.

  • 1167962.
    Yvede, Matilda
    Karlstad University, Faculty of Social and Life Sciences.
    Vad föder våld?: En tudelad studie om våld; som fenomen och som produktiv kraft2008Independent thesis Basic level (degree of Bachelor), 10 points / 15 hpStudent thesis
  • 1167963.
    Yvell, Karin
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Experimental Studies of Deformation Structures in Stainless Steels using EBSD2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    In this thesis, the focus has been the study of deformation structures in stainless steels by using electron backscatter diffraction (EBSD). Via increased knowledge of the evolution of the substructure during deformation, the design and control of the manufacturing process can be improved.

    A relation was found between the active deformation mechanisms, the evolution of low angle boundaries (LABs) and the strain hardening rate. When deformation twinning was an active deformation mechanism in an austenitic stainless steel with lower stacking fault energy (SFE), the strain hardening rate was maintained up to large strains due to formation of LABs. The deformation twin boundaries acted as new obstacles for dislocation slip which in turn increased the formation of LABs even further. During deformation by slip in an austenitic stainless steel with a higher SFE, the strain hardening rate instead decreased when LABs were formed. A high value of SFE promotes dislocation cross slip which in turn increases annihilation of dislocations leading to a minor increase in LAB formation.

    Deformation structures formed in surface grains during in situ tensile tests were found to develop at lower strains than in bulk grains obtained from interrupted conventional tensile tests. This behavior is consistent with the fact that dislocations sources and deformation twinning operate at approximately half the stress on a free surface as compared to the bulk.

    The deformation structures were quantified by measuring size distributions for entities bounded by LABs and high angle boundaries (HABs). The size distributions were found to be well described by bimodal lognormal distribution functions. The average size for the distribution of small grains and subgrains correlated well with the mean free distance of dislocation slip and to the strain hardening.

  • 1167964.
    Yvell, Karin
    Dalarna University, School of Technology and Business Studies, Materials Technology. KTH, Materialvetenskap.
    Experimental Studies of Deformation Structures in Stainless Steels using EBSD2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    In this thesis, the focus has been the study of deformation structures in stainless steels by using electron backscatter diffraction (EBSD). Via increased knowledge of the evolution of the substructure during deformation, the design and control of the manufacturing process can be improved.

    A relation was found between the active deformation mechanisms, the evolution of low angle boundaries (LABs) and the strain hardening rate. When deformation twinning was an active deformation mechanism in an austenitic stainless steel with lower stacking fault energy (SFE), the strain hardening rate was maintained up to large strains due to formation of LABs. The deformation twin boundaries acted as new obstacles for dislocation slip which in turn increased the formation of LABs even further. During deformation by slip in an austenitic stainless steel with a higher SFE, the strain hardening rate instead decreased when LABs were formed. A high value of SFE promotes dislocation cross slip which in turn increases annihilation of dislocations leading to a minor increase in LAB formation.

    Deformation structures formed in surface grains during in situ tensile tests were found to develop at lower strains than in bulk grains obtained from interrupted conventional tensile tests. This behavior is consistent with the fact that dislocations sources and deformation twinning operate at approximately half the stress on a free surface as compared to the bulk.

    The deformation structures were quantified by measuring size distributions for entities bounded by LABs and high angle boundaries (HABs). The size distributions were found to be well described by bimodal lognormal distribution functions. The average size for the distribution of small grains and subgrains correlated well with the mean free distance of dislocation slip and to the strain hardening.

  • 1167965.
    Yvell, Karin
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Engberg, Göran
    Deformation structures in a duplex stainless steel2018In: Materials Science Forum, ISSN 0255-5476, E-ISSN 1662-9752Article in journal (Refereed)
  • 1167966.
    Yvell, Karin
    et al.
    Dalarna University, School of Technology and Business Studies, Materials Technology. KTH, Materialvetenskap.
    Engberg, Göran
    Dalarna University, School of Technology and Business Studies, Materials Technology.
    Deformation structures in a duplex stainless steel2018In: Materials Science Forum, ISSN 0255-5476, E-ISSN 1662-9752, Vol. 941, p. 176-181Article in journal (Refereed)
    Abstract [en]

    The evolution of the deformation structure with strain has been studied using electron backscatter diffraction (EBSD). Samples from interrupted uniaxial tensile tests and from a cyclic tension/compression test were investigated. The evolution of low angle boundaries (LABs) was studied using boundary maps and by measuring the LAB density. From calculations of local misorientations, smaller orientation changes in the substructure can be illustrated. The different orientations developed with strain within a grain, due to operation of different slip systems in different parts of the grain, were studied using a misorientation profile showing substantial orientation changes after a true strain of 0.24. The texture evolution with increasing strain was followed by using inverse pole figures (IPFs). The observed substructure development in the ferritic and austenitic phases could be successfully correlated with the stress-strain curve from a tensile test. LABs were first observed in the different phases when the strain hardening rate changed in appearance indicating that cross slip started to operate as a significant dislocation recovery mechanism. The evolution of the deformation structure is concluded to occur in a similar manner in the austenitic and ferritic phases but with different texture evolution for the two phases.

  • 1167967.
    Yvell, Karin
    et al.
    Dalarna University, School of Technology and Business Studies, Materials Technology.
    Engberg, Göran
    Dalarna University, School of Technology and Business Studies, Materials Technology.
    Microstructure evolution in an austenitic stainless steel during wire rolling2013In: Materials Science Forum, ISSN 0255-5476, E-ISSN 1662-9752, Vol. 753, p. 407-410Article in journal (Refereed)
    Abstract [en]

    Material characterization is of great importance for example to improve and further develop physically based models for predicting the microstructural evolution in steels during and after hot deformation. The aim of this study was to characterize the microstructure evolution during wire rod rolling of an austenitic stainless steel of type AISI 304L in a wire rod block, consisting of eight pairs of rolls, using electron backscatter diffraction. The investigation showed that the grain size in the center of the bar decreases during the first four passes. The grain size decrease from 6.5 Όm after the first roll pass down to 2 Όm, and only small changes was measured in the overall grain size during the last four passes. The subgrain size adopts an almost constant size of 0.9 Όm from the second until the fifth roll pass. During the first 3 passes almost no recrystallization is observed and strain accumulates. Partial recrystallization then starts and for the last 3 passes the recrystallization is almost complete and the texture is nearly random. © (2013) Trans Tech Publications, Switzerland.

  • 1167968.
    Yvell, Karin
    et al.
    Dalarna University, 791 88 Falun, Sweden.
    Engberg, Göran
    Microstructure evolution in an austenitic stainless steel during wire rolling2013In: 5th International Conference on Recrystallization and Grain Growth, ReX and GG 2013, Trans Tech Publications, 2013, Vol. 753, p. 407-410Conference paper (Refereed)
    Abstract [en]

    Material characterization is of great importance for example to improve and further develop physically based models for predicting the microstructural evolution in steels during and after hot deformation. The aim of this study was to characterize the microstructure evolution during wire rod rolling of an austenitic stainless steel of type AISI 304L in a wire rod block, consisting of eight pairs of rolls, using electron backscatter diffraction. The investigation showed that the grain size in the center of the bar decreases during the first four passes. The grain size decrease from 6.5 μm after the first roll pass down to 2 μm, and only small changes was measured in the overall grain size during the last four passes. The subgrain size adopts an almost constant size of 0.9 μm from the second until the fifth roll pass. During the first 3 passes almost no recrystallization is observed and strain accumulates. Partial recrystallization then starts and for the last 3 passes the recrystallization is almost complete and the texture is nearly random.

  • 1167969.
    Yvell, Karin
    et al.
    Material Science, Dalarna University, Falun, Sweden.
    Grehk, Mikael
    Engberg, Göran
    Microstructure characterization of 316L deformed at high strain rates using EBSD2016In: Materials Characterization, ISSN 1044-5803, E-ISSN 1873-4189, Vol. 122, p. 14-21Article in journal (Refereed)
    Abstract [en]

    Specimens from split Hopkinson pressure bar experiments, at strain rates between ~ 1000–9000 s− 1 at room temperature and 500 �C, have been studied using electron backscatter diffraction. No significant differences in the microstructures were observed at different strain rates, but were observed for different strains and temperatures. Size distribution for subgrains with boundary misorientations > 2� can be described as a bimodal lognormal area distribution. The distributions were found to change due to deformation. Part of the distribution describing the large subgrains decreased while the distribution for the small subgrains increased. This is in accordance with deformation being heterogeneous and successively spreading into the undeformed part of individual grains. The variation of the average size for the small subgrain distribution varies with strain but not with strain rate in the tested interval. The mean free distance for dislocation slip, interpreted here as the average size of the distribution of small subgrains, displays a variation with plastic strain which is in accordance with the different stages in the stress-strain curves. The rate of deformation hardening in the linear hardening range is accurately calculated using the variation of the small subgrain size with strain.

  • 1167970.
    Yvell, Karin
    et al.
    Materials Science, Dalarna University, Falun, Sweden.
    Grehk, Mikael
    Hedström, Peter
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Borgenstam, Annika
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Engberg, Göran
    EBSD analysis of surface and bulk microstructure evolution during interrupted tensile testing of a Fe-19Cr-12Ni alloy2018In: Materials Characterization, ISSN 1044-5803, E-ISSN 1873-4189, Vol. 141, p. 8-18Article in journal (Refereed)
    Abstract [en]

    The microstructure evolution in both surface and bulk grains in a pure Fe-19Cr-12Ni alloy has been analyzed using electron backscatter diffraction after tensile testing interrupted at different strains. Surface grains were studied during in situ tensile testing performed in a scanning electron microscope, whereas bulk grains were studied after conventional tensile testing. The evolution of the deformation structure in surface and bulk grains displays a strong resemblance but the strain needed to obtain a similar deformation structure is lower in the case of surface grains. Both slip and twinning are observed to be important deformation mechanisms, whereas deformation-induced martensite formation is of minor importance. Since the stacking fault energy (SFE) is low, ~17 mJ/m2, dynamic recovery by cross slip of un-dissociated dislocations is unfavorable. This reduces the annihilation of dislocations which in turn leads to a significant increase of low angle boundaries with increasing strain. The low SFE also favors formation of deformation twins which reduces the slip distance, leading to a hardening similar to the Hall-Petch relation. The combination of a low ability for cross-slip and a reduced slip distance caused by twinning is concluded to be the main reason for maintaining a high strain-hardening rate up to strains close to necking.

  • 1167971.
    Yvell, Karin
    et al.
    Dalarna University, School of Technology and Business Studies, Materials Technology.
    Grehk, T. M.
    Engberg, Göran
    Dalarna University, School of Technology and Business Studies, Materials Technology.
    Microstructure characterization of 316L deformed at high strain rates using EBSD2016In: Materials Characterization, ISSN 1044-5803, E-ISSN 1873-4189, Vol. 122, p. 14-21Article in journal (Refereed)
    Abstract [en]

    Specimens from split Hopkinson pressure bar experiments, at strain rates between ~ 1000–9000 s− 1 at room temperature and 500 °C, have been studied using electron backscatter diffraction. No significant differences in the microstructures were observed at different strain rates, but were observed for different strains and temperatures. Size distribution for subgrains with boundary misorientations > 2° can be described as a bimodal lognormal area distribution. The distributions were found to change due to deformation. Part of the distribution describing the large subgrains decreased while the distribution for the small subgrains increased. This is in accordance with deformation being heterogeneous and successively spreading into the undeformed part of individual grains. The variation of the average size for the small subgrain distribution varies with strain but not with strain rate in the tested interval. The mean free distance for dislocation slip, interpreted here as the average size of the distribution of small subgrains, displays a variation with plastic strain which is in accordance with the different stages in the stress-strain curves. The rate of deformation hardening in the linear hardening range is accurately calculated using the variation of the small subgrain size with strain.

  • 1167972.
    Yvell, Karin
    et al.
    Dalarna University, School of Technology and Business Studies, Materials Technology.
    Grehk, T. M.
    Hedström, P.
    Borgenstam, A.
    Engberg, Göran
    Dalarna University, School of Technology and Business Studies, Materials Technology.
    EBSD analysis of surface and bulk microstructure evolution during interrupted tensile testing of a Fe-19Cr-12Ni alloy2018In: Materials Characterization, ISSN 1044-5803, E-ISSN 1873-4189, Vol. 141, p. 8-18Article in journal (Refereed)
    Abstract [en]

    Abstract The microstructure evolution in both surface and bulk grains in a pure Fe-19Cr-12Ni alloy has been analyzed using electron backscatter diffraction after tensile testing interrupted at different strains. Surface grains were studied during in situ tensile testing performed in a scanning electron microscope, whereas bulk grains were studied after conventional tensile testing. The evolution of the deformation structure in surface and bulk grains displays a strong resemblance but the strain needed to obtain a similar deformation structure is lower in the case of surface grains. Both slip and twinning are observed to be important deformation mechanisms, whereas deformation-induced martensite formation is of minor importance. Since the stacking fault energy (SFE) is low, 17mJ/m2, dynamic recovery by cross slip of un-dissociated dislocations is unfavorable. This reduces the annihilation of dislocations which in turn leads to a significant increase of low angle boundaries with increasing strain. The low SFE also favors formation of deformation twins which reduces the slip distance, leading to a hardening similar to the Hall-Petch relation. The combination of a low ability for cross-slip and a reduced slip distance caused by twinning is concluded to be the main reason for maintaining a high strain-hardening rate up to strains close to necking.

  • 1167973.
    Yvell, Karin
    et al.
    Dalarna University, School of Technology and Business Studies, Materials Technology.
    Grehk, T. M.
    Hedström, P.
    Borgenstam, A.
    Engberg, Göran
    Dalarna University, School of Technology and Business Studies, Materials Technology.
    Microstructure development in a high-nickel austenitic stainless steel using EBSD during in situ tensile deformation2018In: Materials Characterization, ISSN 1044-5803, E-ISSN 1873-4189, Vol. 135, no Supplement C, p. 228-237Article in journal (Refereed)
    Abstract [en]

    Plastic deformation of surface grains has been observed by electron backscatter diffraction technique during in situ tensile testing of a high-nickel austenitic stainless steel. The evolution of low- and high-angle boundaries as well as the orientation changes within individual grains has been studied. The number of low-angle boundaries and their respective misorientation increases with increasing strain and some of them also evolve into high-angle boundaries leading to grain fragmentation. The annealing twin boundaries successively lose their integrity with increasing strain. The changes in individual grains are characterized by an increasing spread of orientations and by grains moving towards more stable orientations with 〈111〉 or 〈001〉 parallel to the tensile direction. No deformation twins were observed and deformation was assumed to be caused by dislocation slip only.

  • 1167974.
    Yvell, Karin
    et al.
    Materials Science, Dalarna University, Falun, Sweden.
    Grehk, T. M.
    Hedström, Peter
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Borgenstam, Annika
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Engberg, G.
    Microstructure development in a high-nickel austenitic stainless steel using EBSD during in situ tensile deformation2018In: Materials Characterization, ISSN 1044-5803, E-ISSN 1873-4189, Vol. 135, p. 228-237Article in journal (Refereed)
    Abstract [en]

    Plastic deformation of surface grains has been observed by electron backscatter diffraction technique during in situ tensile testing of a high-nickel austenitic stainless steel. The evolution of low- and high-angle boundaries as well as the orientation changes within individual grains has been studied. The number of low-angle boundaries and their respective misorientation increases with increasing strain and some of them also evolve into high-angle boundaries leading to grain fragmentation. The annealing twin boundaries successively lose their integrity with increasing strain. The changes in individual grains are characterized by an increasing spread of orientations and by grains moving towards more stable orientations with < 111 > or < 001 > parallel to the tensile direction. No deformation twins were observed and deformation was assumed to be caused by dislocation slip only.

  • 1167975.
    Yvell, Karin
    et al.
    Dalarna University, SE-791 88 Falun, Sweden.
    Lindgren, Michael
    Bexell, Ulf
    A Microstructural Investigation of Roll Formed Austenitic Stainless Steel2013In: Sheet Metal 2013, Trans Tech Publications, 2013, Vol. 549, p. 364-371Conference paper (Refereed)
    Abstract [en]

    Due to high production rates and the possibility to form complex geometries roll forming has become an increasingly popular forming process for sheet metal. Increasing quantities of high strength steels are used today but can be difficult to form due to their low ductility. One way to partly overcome this problem is to heat the steel in the forming area thus locally increasing the ductility. In the present study partially heated cold rolled high strength AISI 301 type austenitic stainless steel was investigated using electron backscattered diffraction (EBSD), and the results were compared to microhardness measurements. The results show that partial heating will give an almost complete reverse martensite transformation, i.e. martensite (α′) transforms to austenite (γ), close to the surfaces and grain growth in the middle of the steel sheet. The extension of the heat affected zone can be determined using either microhardness or EBSD measurements. Both these measurements can be used to determine the position of the neutral layer after roll forming. The hardness measurement cannot distinguish between microstructural features but the results are in good agreement with the EBSD results for volume fraction of α′-martensite. A major advantage of using EBSD is the possibility to characterize and follow the microstructural development when heating and roll forming.

  • 1167976.
    Yvell, Karin
    et al.
    Dalarna University, School of Technology and Business Studies, Materials Technology.
    Lindgren, Michael
    Bexell, Ulf
    Dalarna University, School of Technology and Business Studies, Materials Technology.
    A microstructural investigation of roll formed austenitic stainless steel2013In: Sheet metal 2013: Key engineering metals, 2013, Vol. 549, p. 364-371Conference paper (Refereed)
    Abstract [en]

    Due to high production rates and the possibility to form complex geometries roll forming has become an increasingly popular forming process for sheet metal. Increasing quantities of high strength steels are used today but can be difficult to form due to their low ductility. One way to partly overcome this problem is to heat the steel in the forming area thus locally increasing the ductility. In the present study partially heated cold rolled high strength AISI 301 type austenitic stainless steel was investigated using electron backscattered diffraction (EBSD), and the results were compared to microhardness measurements. The results show that partial heating will give an almost complete reverse martensite transformation, i.e. martensite (alpha') transforms to austenite (gamma), close to the surfaces and grain growth in the middle of the steel sheet. The extension of the heat affected zone can be determined using either microhardness or EBSD measurements. Both these measurements can be used to determine the position of the neutral layer after roll forming. The hardness measurement cannot distinguish between microstructural features but the results are in good agreement with the EBSD results for volume fraction of alpha'-martensite. A major advantage of using EBSD is the possibility to characterize and follow the microstructural development when heating and roll forming.

  • 1167977.
    Yvell, Malin
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Industrial Ecology.
    El Malla, Dana
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Industrial Ecology.
    Avfallshanteringen i SödraHammarbyhamnen: En studie om möjligheter till förändring av mänskligt beteende beträffande utsorteringen av matavfall2017Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    “Hammarby Sjöstad” was one of the first districts of Stockholm constructed withconsiderations taken to become more environmentally sustainable. Despite the grand visionsfor the project, some elements developed to be more successful than others. One element thatcould be improved upon, is the waste disposal system of the district. This thesis focuses on“Södra Hammarbyhamnen” which utilizes a stationary vacuum system with disposal insertionin connection to the residences. The neighborhood fulfils all the prerequisites for a successfulwaste disposal system, however, these aren’t utilized to capacity. In 2015, the averageresident in central Stockholm sorted approximately 17 kilos of food waste, whilst thecorresponding figure in “Hammarby Sjöstad” was only 13 kilos. As households make up mostof the produced food waste, this report is delimited to focus on households.

    Therefore, the purpose of this study is to identify obstacles that hamper the sorting of foodwaste in “Södra Hammarbyhamnen”. Furthermore, the report covers a concretization of howto inform residents with the intention of increasing waste separation. In combination with ananalysis on human habits, an empirical study was carried out, consisting of surveys andinterviews. Finally, a mapping of the aforementioned obstacles that obstruct waste separationhave been pinpointed in the gathered results. The results indicate that residents perceive a lackof continuity in the flow of information, described by theory as fundamental to create newhabits. Furthermore, it became clear that the accessibility of waste disposal bags can beimproved. Regardless of location, residents felt that the distance to the nearest waste bagdispensary was too long. This study concludes that improvement efforts should conform tothe apophthegm “It should be easy to do it right” to facilitate waste separation of food waste.

  • 1167978.
    Yvert-Hamon, Sophie
    Stockholm University, Faculty of Humanities, Department of French, Italian and Classical Languages.
    Ethos et représentation de l'Autre dans le discours de controverse religieuse de Philippe Duplessis-Mornay: Étude de l'emploi des pronoms dans la préface de deux éditions du Traité de l'eucharistie (1598/1604)2013Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    With the discourse analysis as framework, this study focuses on the ethos, the representation of the Other and the argumentation in the discourse of religious controversy of the protestant Philippe Duplessis-Mornay. The corpus, which consists of the prefaces of two editions of the Traité de l’eucharistie (1598 and 1604), was subject to a systematic survey of the personal pronouns je, nous, vous as well as references to Duplessis-Mornay’s direct opponents, in a diachronic perspective (the two editions have been compared).

    The analysis has shown the discursive strategies of Duplessis-Mornay, including a subtle management of the ethos and the relationship with the Other in order to convince the reader. The build-up of an ethos by an interposed author (frequent use of quotations), observed in the edition of 1598, has increased in that of 1604. This edition is also characterized by an ethos of justification which intends to invalidate an unfavourable prediscursive ethos resulting from adverse reactions to the first edition. The ethos of caritas and the authorial ethos are also very present in the discourse of the author in both editions. In his relation to the Other, Duplessis-Mornay uses a strategic approach, alternating nous inclusif and nous exclusif, and referring most often the notion of vous dans l’erreur to authors recognized by Catholics themselves, through quotations. Only direct opponents of the author are stigmatized by their representation in the third person. Duplessis-Mornay’s discourse, in both prefaces, is characterized by a diplomatic and persuasive attitude.

  • 1167979.
    Yvert-Hamon, Sophie
    Stockholm University, Faculty of Humanities, Department of Romance Studies and Classics.
    Ethos, représentation de l’Autre et argumentation dans le discours de controverse religieuse de Philippe Duplessis-Mornay. Résultats d’une recherche en cours 2017Conference paper (Other academic)
  • 1167980.
    Yvert-Hamon, Sophie
    Stockholm University, Faculty of Humanities, Department of Romance Studies and Classics.
    La citation dans le discours de controverse religieuse: un cas particulier de reformulation?2017Conference paper (Refereed)
  • 1167981.
    Yvert-Hamon, Sophie
    Stockholm University, Faculty of Humanities, Department of Romance Studies and Classics.
    La citation dans le discours de controverse religieuse: un cas particulier de reformulation?2019In: La reformulation: à la recherche d'une frontière / [ed] Houda Landolsi, Maria Svensson, Coco Norén, Uppsala: Acta Universitatis Upsaliensis, 2019Chapter in book (Other academic)
  • 1167982.
    Yvert-Hamon, Sophie
    Stockholm University, Faculty of Humanities, Department of Romance Studies and Classics.
    La vérité dans la dynamique de la controverse. Philippe Duplessis-Mornay et la préface du Traité de l’eucharistie2019Conference paper (Refereed)
  • 1167983.
    Yvert-Hamon, Sophie
    Stockholm University, Faculty of Humanities, Department of Romance Studies and Classics.
    L'emploi des pronoms je, nous et vous dans le discours de controverse religieuse en France après les guerres de religion2015In: Studii de Lingvistica, ISSN 2248-2547, E-ISSN 2284-5437, no 5, p. 129-154Article in journal (Refereed)
    Abstract [en]

    This study explores the ethos, the representation of the Other and argumentation in the discourse of religious controversy between Catholics and Protestants in the sixteenth and seventeenth centuries in France. During the period following the Wars of Religion, which is characterized by a regulated coexistence of the two religions in accordance with the Edict of Nantes (1598), a significant increase in the number of publications relating to religious controversy is observed, as the fight is displaced to a discursive level. The corpus for this study is composed of several publications by the Protestant Philippe Duplessis-Mornay. Using the framework of Discourse Analysis, our study makes a systematic survey of the personal pronouns in the texts written by the author in order to analyze his discursive strategies. The purpose of this study is to contribute to exploring a new corpus for discourse analysis as well as to further our understanding of religious controversies.

  • 1167984.
    Yvert-Hamon, Sophie
    Stockholm University, Faculty of Humanities, Department of Romance Studies and Classics.
    Stratégies de désignation dans le discours politique catholique et protestant pendant les guerres de religion : le tournant décisif des premières années de règne d’Henri IV (1589-1593)2017In: 20th Nordic Romanist Conference: Book of Abstracts, 2017, p. 94-95Conference paper (Refereed)
  • 1167985.
    Yvert-Hamon, Sophie
    Stockholm University, Faculty of Humanities, Department of Romance Studies and Classics.
    Stratégies de désignation dans le discours politique protestant après la conversion du roi Henri IV. L’exemple de la Lettre au Roy de 1593 2016In: Political Discourse and the Extremes in the Romance Speaking Countries: Linguistics and Social Science Perspectives: Abstracts, 2016, p. 23-23Conference paper (Refereed)
  • 1167986.
    Yvert-Hamon, Sophie
    Stockholm University, Faculty of Humanities, Department of Romance Studies and Classics.
    Tradition and transformation through the religious controversies between Catholics and Protestants after the French Wars of Religion 2017Conference paper (Refereed)
  • 1167987.
    Yves, Hawa
    Blekinge Institute of Technology, School of Engineering, Department of Signal Processing.
    A Study of Fast Backprojection Algorithm for UWB SAR and a Comparison between Fast- and Global Backprojection2008Independent thesis Advanced level (degree of Master (Two Years))Student thesis
    Abstract [en]

    In this thesis, we present a study of the Fast Backprojection (FBP) known to be a fast time-domain algorithm for image retrieval in Synthetic Aperture Radar (SAR). As a time domain algorithm, FBP possesses inherent advantages such as perfect motion compensation, unlimited scene size, wide bandwidth and ability to handle long integration angles. Although FBP reproduces SAR images on pixel-by-pixel basis, the processing time for FBP is reduced significant compared to the Global Backprojection (GBP) with a heavy computational load. For GBP, the number of operations to process a N×N SAR image with N aperture positions is proportional to N . Whereas, the number of operation required by FBP in the same case is reduced by a factor of sqrt(N) i.e. proportional to N2sqrt(N). We give a detailed explanation on how to implement FBP in Matlab in order to retrieve a SAR image. We explain about different techniques of interpolation used to obtain a high quality image. We also present a method to compare between interpolation techniques in term of SAR image quality and processing time. A comparison between FBP and GBP is also a topic to be discussed in this thesis. In this comparison, the processing time in theory and reality will be focused.

  • 1167988.
    Yvesand, Lina
    et al.
    Linnaeus University, Faculty of Health, Social Work and Behavioural Sciences, School of Education, Psychology and Sport Science.
    Fors, Sophie
    Linnaeus University, Faculty of Health, Social Work and Behavioural Sciences, School of Education, Psychology and Sport Science.
    Åtgärdsprogram för elever med svenska som andraspråk: En jämförande studie av fyra elevers åtgärdsprogram i två skolor2013Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
  • 1167989.
    Yvette Tanila, Nchombua
    Umeå University, Faculty of Social Sciences, Umeå School of Business and Economics (USBE).
    A Systematic Analysis of the Factors that Drive SMEs to Internationalisation and the Paths followed by these Firms: An Exploratory Study of Four Highly Technological Firms in Sweden2011Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Due to globalization and other factors, the business environment of small and medium sized enterprises (SMEs) is radically changing. In order for these firms to cope with increased competition and business opportunities in globalised markets, they have to strengthen their innovative capabilities and internationalise their business activities (Rammer and Schmiele, 2008, p.3). In this paper, I investigate the determinants that drive highly technological SMES from Umea (Sweden) to other markets abroad and the paths followed by these SMES.The choice of Highly technological SMES (i.e. SMES with innovative solutions) is mainly due to the fact that they internationalise at a fast pace and often bypass the traditional methods of internationalisation proposed by the Uppsala model of internationalisation. The Uppsala model of internationalisation was used as a reference point where similarities and discrepancies between findings was analysed. In addition to this, a general analysis on how managerial internationalisation strategies are drawn was carefully outlined. Core focus is placed on the importance of resource evaluation, proper entry modes, networking and the inclusion of deinternationalisation as a contingency plan in case the market becomes unresponsive due to rise in cost or high competitive pressures.

     

    By carrying out a qualitative research and a cross-sectional analysis of some four firms operating in the highly technological sector of the Swedish economy, I obtained findings that; Swedish SMEs do not seem to be pushed to internationalisation by increased competition (such as threat of market position through new entrants or a fierce price competition), but rather go abroad with innovative activities when they have a niche market position, i.e. a low number of competitors and a patent-based technology advantage (Rammer and Shmiele,2008,p.3). Concerning the paths followed by these SMEs to international markets, I outlined that the starting point of SMEs is to carry out an evaluation of their resources (physical, human and financial).Careful evaluation of these resources will enable managers detect if the company can cope with foreign expansion. With this information, they can seek for resources that are not internally possess by the company through establishing networks with distributors, firms, suppliers and their customers. With this network, the firm can obtain both market specific and general knowledge of the foreign market. With all this information at hand, the entry mode must be considered. It is of great importance because the cost and risk involve in foreign markets are mostly associated with the chosen entry mode. Because international expansion involves taking risk, I advise managers on setting up a threshold where they can withdraw if the value of the firm begins to drop. However, I urge them to be careful not to withdraw either prematurely or too late. Therefore, I conclude that though international expansion can help SMEs overcome resource constraints, they should however be careful on how they internationalised by following the paths I outlined.

     

     

     

    Keywords; Internationalisation, Networking, Resourced Based Perspectives, International Entry Mode, SMEs, Deinternationalisation

  • 1167990.
    Yvling, Mikael
    Swedish National Defence College.
    Operation Anaconda och taktik kopplat mot Wardens teori2014Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    John A. Warden III har utvecklat en teori om hur luftmakt skall användas vid mellanstatliga konflikter, teorin är utvecklad för strategiskt bruk. Wardens teori prövades under Gulfkriget 1990-1991 och visade sig var väldigt effektiv. 

    Det här arbetet skall undersöka om Wardens teori kan förklara det taktiska samspelet mellan mark- och luftstridskrafter.  Arbetet skall även undersöka om Wardens teori kan förklara taktiska händelser. Undersökningen kommer att göras genom att analyser Operation Anaconda utifrån Wardens teori.   

  • 1167991. Yvling, Sofie
    Miljöriskanalys vid Smurfit Kappa Kraftliner Piteå2007Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
  • 1167992. Yvon-Durocher, Gabriel
    et al.
    Allen, Andrew P.
    Bastviken, David
    Conrad, Ralf
    Gudasz, Cristian
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    St-Pierre, Annick
    Thanh-Duc, Nguyen
    del Giorgio, Paul A.
    Methane fluxes show consistent temperature dependence across microbial to ecosystem scales2014In: Nature, ISSN 0028-0836, E-ISSN 1476-4687, Vol. 507, no 7493, p. 488-491Article in journal (Refereed)
    Abstract [en]

    Methane (CH4) is an important greenhouse gas because it has 25 times the global warming potential of carbon dioxide (CO2) by mass over a century(1). Recent calculations suggest that atmospheric CH4 emissions have been responsible for approximately 20% of Earth's warming since pre-industrial times(2). Understanding how CH4 emissions from ecosystems will respond to expected increases in global temperature is therefore fundamental to predicting whether the carbon cycle will mitigate or accelerate climate change. Methanogenesis is the terminal step in the remineralization of organic matter and is carried out by strictly anaerobic Archaea(3). Like most other forms of metabolism, methanogenesis is temperature-dependent(4,5). However, it is not yet known how this physiological response combines with other biotic processes (for example, methanotrophy(6), substrate supply(3,7), microbial community composition(8)) and abiotic processes (for example, water-table depth(9,10)) to determine the temperature dependence of ecosystem-level CH4 emissions. It is also not known whether CH4 emissions at the ecosystem level have a fundamentally different temperature dependence than other key fluxes in the carbon cycle, such as photosynthesis and respiration. Here we use meta-analyses to show that seasonal variations in CH4 emissions from a wide range of ecosystems exhibit an average temperature dependence similar to that of CH4 production derived from pure cultures of methanogens and anaerobic microbial communities. This average temperature dependence (0.96 electron volts (eV)), which corresponds to a 57-fold increase between 0 and 30 degrees C, is considerably higher than previously observed for respiration (approximately 0.65 eV)(11) and photosynthesis (approximately 0.3 eV)(12). As a result, we show that both the emission of CH4 and the ratio of CH4 to CO2 emissions increase markedly with seasonal increases in temperature. Our findings suggest that global warming may have a large impact on the relative contributions of CO2 and CH4 to total greenhouse gas emissions from aquatic ecosystems, terrestrial wetlands and rice paddies.

  • 1167993. Yvon-Durocher, Gabriel
    et al.
    Allen, Andrew P.
    Bastviken, David
    Conrad, Ralf
    Gudasz, Cristian
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences. ARCUM; Department of Ecology and Genetics, Limnology, Uppsala University, Norbyvägen 18D, SE-752 36, Uppsala Sweden; Department of Ecology and Evolutionary Biology, Princeton University, Princeton, 106A Guyot Hall, New Jersey 08544, USA.
    St-Pierre, Annick
    Thanh-Duc, Nguyen
    del Giorgio, Paul A.
    Methane fluxes show consistent temperature dependence across microbial to ecosystem scales2014In: Nature, ISSN 0028-0836, E-ISSN 1476-4687, Vol. 507, no 7493, p. 488-491Article in journal (Refereed)
    Abstract [en]

    Methane (CH4) is an important greenhouse gas because it has 25 times the global warming potential of carbon dioxide (CO2) by mass over a century(1). Recent calculations suggest that atmospheric CH4 emissions have been responsible for approximately 20% of Earth's warming since pre-industrial times(2). Understanding how CH4 emissions from ecosystems will respond to expected increases in global temperature is therefore fundamental to predicting whether the carbon cycle will mitigate or accelerate climate change. Methanogenesis is the terminal step in the remineralization of organic matter and is carried out by strictly anaerobic Archaea(3). Like most other forms of metabolism, methanogenesis is temperature-dependent(4,5). However, it is not yet known how this physiological response combines with other biotic processes (for example, methanotrophy(6), substrate supply(3,7), microbial community composition(8)) and abiotic processes (for example, water-table depth(9,10)) to determine the temperature dependence of ecosystem-level CH4 emissions. It is also not known whether CH4 emissions at the ecosystem level have a fundamentally different temperature dependence than other key fluxes in the carbon cycle, such as photosynthesis and respiration. Here we use meta-analyses to show that seasonal variations in CH4 emissions from a wide range of ecosystems exhibit an average temperature dependence similar to that of CH4 production derived from pure cultures of methanogens and anaerobic microbial communities. This average temperature dependence (0.96 electron volts (eV)), which corresponds to a 57-fold increase between 0 and 30 degrees C, is considerably higher than previously observed for respiration (approximately 0.65 eV)(11) and photosynthesis (approximately 0.3 eV)(12). As a result, we show that both the emission of CH4 and the ratio of CH4 to CO2 emissions increase markedly with seasonal increases in temperature. Our findings suggest that global warming may have a large impact on the relative contributions of CO2 and CH4 to total greenhouse gas emissions from aquatic ecosystems, terrestrial wetlands and rice paddies.

  • 1167994.
    Yvon-Durocher, Gabriel
    et al.
    University of Exeter, Penryn, UK.
    Allen, Andrew P.
    Macquarie University, Sydney, Australia .
    Bastviken, David
    Linköping University, The Tema Institute, Department of Water and Environmental Studies. Linköping University, Faculty of Arts and Sciences.
    Conrad, Ralf
    Max-Planck-Institute for Terrestrial Microbiology, Marburg, Germany .
    Gudasz, Cristian
    Umeå University, Sweden; Uppsala University, Sweden .
    St-Pierre, Annick
    University of Quebec, Canada .
    Thanh-Duc, Nguyen
    University of New Hampshire, Durham, USA.
    del Giorgio, Paul A.
    Université du Québec à Montréal, Canada.
    Methane fluxes show consistent temperature dependence across microbial to ecosystem scales2014In: Nature, ISSN 0028-0836, E-ISSN 1476-4687, Vol. 507, no 7493, p. 488-491Article in journal (Refereed)
    Abstract [en]

    Methane (CH4) is an important greenhouse gas because it has 25 times the global warming potential of carbon dioxide (CO2) by mass over a century(1). Recent calculations suggest that atmospheric CH4 emissions have been responsible for approximately 20% of Earths warming since pre-industrial times(2). Understanding how CH4 emissions from ecosystems will respond to expected increases in global temperature is therefore fundamental to predicting whether the carbon cycle will mitigate or accelerate climate change. Methanogenesis is the terminal step in the remineralization of organic matter and is carried out by strictly anaerobic Archaea(3). Like most other forms of metabolism, methanogenesis is temperature-dependent(4,5). However, it is not yet known how this physiological response combines with other biotic processes (for example, methanotrophy(6), substrate supply(3,7), microbial community composition(8)) and abiotic processes (for example, water-table depth(9,10)) to determine the temperature dependence of ecosystem-level CH4 emissions. It is also not known whether CH4 emissions at the ecosystem level have a fundamentally different temperature dependence than other key fluxes in the carbon cycle, such as photosynthesis and respiration. Here we use meta-analyses to show that seasonal variations in CH4 emissions from a wide range of ecosystems exhibit an average temperature dependence similar to that of CH4 production derived from pure cultures of methanogens and anaerobic microbial communities. This average temperature dependence (0.96 electron volts (eV)), which corresponds to a 57-fold increase between 0 and 30 degrees C, is considerably higher than previously observed for respiration (approximately 0.65 eV)(11) and photosynthesis (approximately 0.3 eV)(12). As a result, we show that both the emission of CH4 and the ratio of CH4 to CO2 emissions increase markedly with seasonal increases in temperature. Our findings suggest that global warming may have a large impact on the relative contributions of CO2 and CH4 to total greenhouse gas emissions from aquatic ecosystems, terrestrial wetlands and rice paddies.

  • 1167995.
    Yvon-Durocher, Gabriel
    et al.
    Queen Mary University London.
    Reiss, Julia
    Queen Mary University London.
    Blanchard, Julia
    Cefas Lowestoft Lab.
    Ebenman, Bo
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Biology . Linköping University, The Institute of Technology.
    Perkins, Danie lM
    Queen Mary University London.
    Reuman, Daniel C
    University London Imperial College of Science Technology and Medicine.
    Thierry, Aaron
    University of Sheffield.
    Woodward, Guy
    Queen Mary University London.
    Petchey, Owen L
    University of Sheffield.
    Across ecosystem comparisons of size structure: methods, approaches and prospects2011In: OIKOS, ISSN 0030-1299, Vol. 120, no 4, p. 550-563Article in journal (Refereed)
    Abstract [en]

    Understanding how ecological communities are structured and how this may vary between different types of ecosystems is a fundamental question in ecology. We develop a general framework for quantifying size-structure within and among different ecosystem types (e. g. terrestrial, freshwater or marine), via the use of a suite of bivariate relationships between organismal size and properties of individuals, populations, assemblages, pair-wise interactions, and network topology. Each of these relationships can be considered a dimension of size-structure, along which real communities lie on a continuous scale. For example, the strength, slope, or elevation of the body mass-versus-abundance or predator size-versus-prey size relationships may vary systematically among ecosystem types. We draw on examples from the literature and suggest new ways to use allometries for comparing among ecosystem types, which we illustrate by applying them to published data. Finally, we discuss how dimensions of size-structure are interconnected and how we could approach this complex hierarchy systematically. We conclude: (1) there are multiple dimensions of size-structure; (2) communities may be size-structured in some of these dimensions, but not necessarily in others; (3) across-system comparisons via rigorous quantitative statistical methods are possible, and (4) insufficient data are currently available to illuminate thoroughly the full extent and nature of differences in size-structure among ecosystem types.

  • 1167996.
    Yvonne, Ceraolo
    et al.
    Blekinge Institute of Technology, School of Management.
    Elina, Kettinen
    Blekinge Institute of Technology, School of Management.
    Verksamhetsstyrning med fokus på intressenters och medarbetares betydelse: ett fundament för företagens varaktiga framgång?2012Independent thesis Basic level (degree of Bachelor)Student thesis
    Abstract [sv]

    We would like to gain a more in depth knowledge of whether the modern orientations both within corporate governance and control philosophy lay the foundation for enterprises’ more sustainable success. These both modern orientations are increasingly focusing on the importance of enterprises’ setting of goals and visions on the basis of stake holders’ interests and the employees’ more active engagement in and motivation for the goal achievement. Despite these common inherent characteristics, it is not evident from current scientific debate how such integration actually emerges in the control philosophies of the enterprises. However, the above mentioned common inherent characteristics, focused on the stakeholders’ interests and employee’s active engagement, could support our view on the broader perspective of steering and organizing of enterprises. The purpose of our thesis is to analyze whether the modern orientations both within corporate governance and performance management could establish a joint view on steering and organizing of enterprises, where the setting of targets and visions are based on the stake holders’ interests and where the enterprises are more oriented to interact with their surroundings. These strategies need to be thoroughly embedded with the employees throughout the whole organization. As a consequence we are especially interested whether our illustration of a more holistic perspective of steering and organizing of enterprises with emphasis on increasing consideration both on the stakeholders’ interests and on the employees’ more active engagement and motivation, could bring more positive outcomes for enterprises’ goal fulfillment and adaptability. Furthermore, we have found a number of indications suggesting that such a holistic perspective of steering and organizing of enterprises could lay the foundation for sustainable success of the enterprises. However, the concept of success can be defined through several different measurements. Success depends highly on the individual circumstances in each organization, whereby every enterprise needs to define its own criteria. Accordingly, we think a sustainable success requires that the enterprises’ targets and visions ate defined in line with the stake holders’ interests. The next step would be to transform these goals into concrete operational activities that are closely integrated in the daily work. It is therefore critical that the enterprises’ strategies are thoroughly embedded with the employees in order to be able to adapt the business to new challenges that the organization might face from time to time. By means of a qualitative literature study both within corporate governance and control philosophies, combined with an empirical study focused on a few enterprises’ control philosophy, we have found support for our assumption of the potential for a more holistic perspective of steering and organizing of enterprises. Such a holistic perspective for control philosophy is well in line with the development of the modern corporate governance theories and modern theories on control philosophies emphasizing the stakeholders' interests and the employees’ active commitment towards goal achievement. Key words: corporate governance, internal and external control mechanisms, control philosophy, stakeholders, balanced scorecard, organizational culture, success.

  • 1167997.
    Yvonne, Hirdman
    Stockholm University, Faculty of Humanities, Department of History.
    Alva Myrdal: the passionate mind2008Book (Other (popular science, discussion, etc.))
  • 1167998.
    Yxe, Jessica
    Stockholm University, Faculty of Humanities, Department of Culture and Aesthetics.
    Skenbar objektivitet: Om jämställdhetsidealens väg in i den medicinska diskursen2016Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The aim of this study is to show how the ideas of gender equality in the late 1970 ́s and early 80 ́s were expressed in Swedish medical discourse. The questions asked are primarily how the ideas came to matter in medical discourse as well as the resistance against these ideas. The primary method used is a modified form of discourse analysis, to suit the aim of this study. The study draws upon three Official Reports of the Swedish Government. Prior research has found that ideas of female submission were a dominant part of the medical discourse, as well as the image of the caring mother. Research has also found that the traditional image of male and female as different species were in a profound reform process, due to, for example, the feminist revolutions, in which gender equality became a prioritized part of the international political agenda.

    This study shows that the resistance to the ideas of gender equality within the medical discourse was still hard to break trough in the early 1980 ́s. The women that were represented in medical studies, as scientists or as a target for research, were minimal or not represented at all – but they who did illustrates how the androcentric ideals of the medical discourse dominated the selection of objects to research, as well as the research itself. This study also shows that, even though the ideas of gender equality were politically accepted, and academic expressions of the opposite opinion were not, the expectations of men and women were still rooted in older ideas of the rational working man and the emotional house wife.

    Keywords: Gender, Medicine, Androcentrism, Discourse, Official Reports of the

    Swedish Government

  • 1167999.
    Yxenholt, Louise
    Karlstad University, Faculty of Arts and Social Sciences (starting 2013), Karlstad Business School.
    Att överskatta sin egen förmåga & tidsinkonsistens: En studie om hur gymnasieelever överskattar sin egen förmåga och effekten av tidsinkonsistens2016Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Overconfidence is most easily explained by individuals who overestimate their own ability and knowledge. Time inconsistency is a concept that many people can identify with. It involves making a decision about the future, but when it is time to execute the decision individual’s change their minds. This study was done to investigate the overconfidence and the time-inconsistency of students in high school. Between 9-12 days before the students had a test in mathematics, they were given a questionnaire consisting of 4 questions. Just before they would write their tests they had to answer the same questionnaire again. One question focused on grades, and the students would then try to estimate what grade their test scores would correspond. The responses from both questionnaires were then compared with the actual grade to see if the students were overconfident about their knowledge of mathematics. The results showed that about 54 percent of the students were overconfident at the first questionnaire and around 44 percent at the second questionnaire. 60 percent of the boys were overconfident at the first questionnaire and about 47 percent at the second questionnaire. For the girls, it was about 51 percent that was overconfident at the first questionnaire, and about 43 percent at the second questionnaire. The result then showed that both boys and girls tend to be overconfident. To investigate time-inconsistency, students' expected rating at the first questionnaire were compared with their expected rating on the second questionnaire. About 31 percent of all students were time-inconsistent, as they changed the expected rating on the second questionnaire. About 30 percent of the boys and about 32 percent of the girls were time-inconsistent. The results showed therefore not much difference between the genders. This means that most students were time-consistent, they did not change their views on their knowledge in mathematics on the second questionnaire.

  • 1168000.
    Yxfeldt, A
    et al.
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Reumatology.
    Wållberg-Jonsson, Solveig
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Reumatology.
    Hultdin, J
    Umeå University, Faculty of Medicine, Department of Medical Biosciences.
    Rantapää-Dahlqvist, Solbritt
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Reumatology.
    Homocysteine in patients with rheumatoid arthritis in relation to inflammation and B-vitamin treatment2003In: Scandinavian Journal of Rheumatology, ISSN 0300-9742, E-ISSN 1502-7732, Vol. 32, no 4, p. 205-210Article in journal (Refereed)
23357233582335923360233612336223363 1167951 - 1168000 of 1207337
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