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  • 7651.
    Abrikosov, Igor A.
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering.
    Alling, Björn
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Steneteg, Peter
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Hultberg, Lasse
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, Faculty of Science & Engineering.
    Hellman, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering.
    Yu Mosyagin, Igor
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering. Department of Theoretical Physics and Quantum Technologies, National Research, Technological University MISiS, Moscow, Russia.
    Lugovskoy, Andrey V.
    Department of Theoretical Physics and Quantum Technologies, National Research, Technological University MISiS, Russia.
    Barannikova, Svetlana A.
    Institute of Strength Physics and Materials Science, Siberian Branch of Russian Academy of Science, Tomsk, Russia; Department of Physics and Engineering, Tomsk State University, Tomsk, Russia.
    Finite Temperature, Magnetic, and Many-Body Effects in Ab Initio Simulations of Alloy Thermodynamics2013In: TMS2013 Supplemental Proceedings, John Wiley & Sons, 2013, p. 617-626Chapter in book (Refereed)
    Abstract [en]

    Ab initio electronic structure theory is known as a useful tool for prediction of materials properties. However, majority of simulations still deal with calculations in the framework of density functional theory with local or semi-local functionals carried out at zero temperature. We present new methodological solution.s, which go beyond this approach and explicitly take finite temperature, magnetic, and many-body effects into account. Considering Ti-based alloys, we discuss !imitations of the quasiharmonic approximation for the treatment of lattice vibrations, and present an accurate and easily extendable method to calculate free ,energies of strongly anharmonic solids. We underline the necessity to going beyond the state-of-the-art techniques for the determination of effective cluster interactions in systems exhibiting mctal-to-insulator transition, and describe a unified cluster expansion approach developed for this class of materials. Finally, we outline a first-principles method, disordered local moments molecular dynamics, for calculations of thermodynamic properties of magnetic alloys, like Cr1-x,.AlxN, in their high-temperature paramagnetic state. Our results unambiguously demonstrate importance of finite temperature effects in theoretical calculations ofthermodynamic properties ofmaterials.

  • 7652.
    Abrikosov, Igor
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics .
    Alling, Björn
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics .
    Asker, Christian
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics .
    Ruban, A.V.
    Department of Material Science and Engineering Royal Institute of Technology.
    Phase Stabilities of Alloys From First-Principles2008In: XVII International Materials Research Congress,2008, Mexico: Mexico , 2008Conference paper (Refereed)
  • 7653.
    Abrikosov, Igor
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, The Institute of Technology.
    Ekholm, Marcus
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, The Institute of Technology.
    Ponomareva, Alena V.
    Theoretical Physics Department, Moscow Steel and Alloys Institute, Russua.
    Barannikova, Svetlana A.
    Institute of Strength Physics and Materials Science, Siberian Branch of Russian Academy of Science, Tomsk, Russia.
    Importance of Thermally Induced Magnetic Excitations in First-principles Simulations of Elastic Properties of Transition Metal Alloys2012In: Solid State Phenomena, ISSN 1012-0394, E-ISSN 1662-9779, Vol. 190, p. 291-294Article in journal (Refereed)
    Abstract [en]

    We demonstrate the importance of accounting for the complex magnetic ground state and finite temperature magnetic excitations in theoretical simulations of structural and elastic properties of transition metal alloys. Considering Fe72Cr16Ni12 face centered cubic (fcc) alloy, we compare results of first-principles calculations carried out for ferromagnetic and non-magnetic states, as well as for the state with disordered local moments. We show that the latter gives much more accurate description of the elastic properties for paramagnetic alloys. We carry out a determination of the magnetic ground state for fcc Fe-Mn alloys, considering collinear, as well as non-collinear states, and show the sensitively of structural and elastic properties in this system to the detailed alignment between magnetic moments. We therefore conclude that it is essential to develop accurate models of the magnetic state for the predictive description of properties of transition metal alloys.

  • 7654.
    Abrikosov, Igor
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics . Linköping University, The Institute of Technology.
    Fors, Cecilia
    Nobelpriset som fortfarande är en gåta2010In: Fysikaktuellt, ISSN 0283-9148, no 2, p. 14-14Article in journal (Other (popular science, discussion, etc.))
  • 7655.
    Abrikosov, Igor
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, The Institute of Technology.
    Kissavos, Andreas E.
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, The Institute of Technology.
    Liot, Francois
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, The Institute of Technology.
    Alling, Björn
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, The Institute of Technology.
    Simak, Sergey
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, The Institute of Technology.
    Peil, O.
    Applied Materials Physics, Department of Materials Science and Engineering, Royal Institute of Technology, SE-10044 Stockholm, Sweden.
    Ruban, A. V.
    Applied Materials Physics, Department of Materials Science and Engineering, Royal Institute of Technology, SE-10044 Stockholm, Sweden.
    Competition between Magnetic Structures in the Fe-Rich FCC FeNi Alloys2007In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 76, no 1, p. 014434-Article in journal (Refereed)
    Abstract [en]

    We report on the results of a systematic ab initio study of the magnetic structure of Fe rich fcc FeNi binary alloys for Ni concentrations up to 50 at. %. Calculations are carried out within density-functional theory using two complementary techniques, one based on the exact muffin-tin orbital theory within the coherent potential approximation and another one based on the projector augmented-wave method. We observe that the evolution of the magnetic structure of the alloy with increasing Ni concentration is determined by a competition between a large number of magnetic states, collinear as well as noncollinear, all close in energy. We emphasize a series of transitions between these magnetic structures, in particular we have investigated a competition between disordered local moment configurations, spin spiral states, the double layer antiferromagnetic state, and the ferromagnetic phase, as well as the ferrimagnetic phase with a single spin flipped with respect to all others. We show that the latter should be particularly important for the understanding of the magnetic structure of the Invar alloys.

  • 7656.
    Abrikosov, Igor
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, The Institute of Technology.
    Knutsson, Axel
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, The Institute of Technology.
    Alling, Björn
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, The Institute of Technology.
    Tasnádi, Ferenc
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, The Institute of Technology.
    Lind, Hans
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, The Institute of Technology.
    Hultman, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Odén, Magnus
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, The Institute of Technology.
    Phase Stability and Elasticity of TiAlN2011In: Materials, ISSN 1996-1944, E-ISSN 1996-1944, Vol. 4, no 9, p. 1599-1618Article in journal (Refereed)
    Abstract [en]

    We review results of recent combined theoretical and experimental studies of Ti1−xAlxN, an archetypical alloy system material for hard-coating applications. Theoretical simulations of lattice parameters, mixing enthalpies, and elastic properties are presented. Calculated phase diagrams at ambient pressure, as well as at pressure of 10 GPa, show a wide miscibility gap and broad region of compositions and temperatures where the spinodal decomposition takes place. The strong dependence of the elastic properties and sound wave anisotropy on the Al-content offers detailed understanding of the spinodal decomposition and age hardening in Ti1−xAlxN alloy films and multilayers. TiAlN/TiN multilayers can further improve the hardness and thermal stability compared to TiAlN since they offer means to influence the kinetics of the favorable spinodal decomposition and suppress the detrimental transformation to w-AlN. Here, we show that a 100 degree improvement in terms of w-AlN suppression can be achieved, which is of importance when the coating is used as a protective coating on metal cutting inserts.

  • 7657.
    Abrikosov, Igor
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, The Institute of Technology.
    Liot, Francois
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, The Institute of Technology.
    Marten, Tobias
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, The Institute of Technology.
    Smirnova, E. A.
    Theoretical Physics Department, Moscov Steel and Alloys Institute, Moscow, Russia.
    Magnetism in systems with reduced dimensionality and chemical disorder: the local environment effects2006In: Journal of Magnetism and Magnetic Materials, ISSN 0304-8853, E-ISSN 1873-4766, Vol. 300, no 1, p. 211-215Article in journal (Refereed)
    Abstract [en]

    We study influence of the local chemical environment, the so-called local environment effects, on the electronic structure and properties of magnetic systems with reduced dimensionality and chemical disorder, and show that they play a crucial role in a vicinity of magnetic instability. As a model, we consider Fe–Ni Invar. We present results obtained from ab initio calculations of the electronic structure, magnetic moments, and exchange interactions in random fcc Fe–Ni alloy, for a single monolayer alloy film on a Cu (0 0 1) substrate as well as in the bulk. We analyze the difference between the film and the bulk magnetization, which is found to be most pronounced for dilute alloys. We also analyze a sensitivity of the individual magnetic moments and effective exchange parameters to the local chemical environment of the atoms.

  • 7658.
    Abrikosov, Igor
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, The Institute of Technology.
    Marten, Tobias
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, The Institute of Technology.
    Olovsson, Weine
    Condensed Matter Theory Group, Department of Physics, Uppsala University, SE-751 21 Uppsala, Sweden.
    Local environment effects in random metallic alloys2005In: The Science of Complex Alloy Phases: proceedings of a symposium held during the TMS Annual Meeting and Exhibition in San Francisco, California, USA, February 13-17, 2005, to honor the Wiliam Hume-Rothery Award recipient Professor Uichiro Mizutani / [ed] Thaddeus B. Massalski and Patrice E. A. Turchi, USA: TMS , 2005, 1, p. 87-108Chapter in book (Other academic)
    Abstract [en]

    This book is published in honor of the 2005 Hume-Rothery Award Recipient, Uichiro Mizutani. It emphasizes both theoretical and experimental aspects of electronic, structural, and thermodynamic properties of complex alloy phases. Leading experts provide an assessment of our current understanding of the structural properties of complex materials, including quasicrystalline and amorphous alloys. Special emphasis is placed on our understanding of why nature is able to stabilize complex atomic arrangements and on recent results related to structurally complex alloy phases. These topics, in the spirit of the work carried out by U. Mizutani, constitute the main theme of the book

  • 7659.
    Abrikosov, Igor
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics .
    Marten, Tobias
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics .
    Olsson, P.
    Uppsala University.
    Simak, Sergey
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics .
    Electronic theory of materials properties: from fundamental understanding towards materials design2006Report (Other academic)
    Abstract [en]

           

  • 7660.
    Abrikosov, Igor
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics .
    Mikhaylushkin, Arkady
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics .
    Asker, Christian
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics .
    Simak, Sergey
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics .
    Ab initio modeling of alloying effects at extreme conditions2008In: Second EuroMinScI Conference,2008, France: ESF , 2008Conference paper (Refereed)
    Abstract [en]

       

  • 7661.
    Abrikosov, Igor
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, The Institute of Technology.
    Nikonov, A. Yu
    Russian Academic Science, Russia .
    Ponomareva, A. V.
    National University of Science and Technology MISiS, Russia .
    Dmitriev, A. I.
    Russian Academic Science, Russia National Research Tomsk State University, Russia .
    Barannikova, S. A.
    Russian Academic Science, Russia National Research Tomsk State University, Russia .
    Theoretical Modeling of Thermodynamic and Mechanical Properties of the Pure Components of Ti and Zr Based Alloys Using the Exact Muffin-Tin Orbitals Method2014In: Russian Physics Journal, ISSN 1064-8887, E-ISSN 1573-9228, Vol. 56, no 9, p. 1030-1038Article in journal (Refereed)
    Abstract [en]

    The exact muffin-tin orbitals (EMTO) method belongs to the third and latest generation of first-principles methods of calculating the electronic structure of materials in the so-called approximation of muffin-tin (MT) orbitals within the framework of the density functional theory. A study has been performed of its applicability for modeling the thermodynamic and mechanical properties of the pure components of Ti and Zr based alloys. The total energies of Ti, Zr, Nb, V, Mo, and Al are calculated in three crystal structures - face-centered cubic (FCC), body-centered cubic (BCC), and hexagonal close-packed (HCP). For all of these elements and crystal structures, we have calculated the theoretical values of the lattice constants, elastic constants, and equations of state. The stable crystal structures have been determined. In all cases, calculations by the EMTO method predict the correct structure of the ground state. For stable structures we compared the obtained results with experiment and with calculations using full potential methods. We have demonstrated the reliability of the EMTO method and conclude that its further application for effective modeling of the properties of disordered alloys based on Ti and Zr is possible.

  • 7662.
    Abrikosov, Igor
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, The Institute of Technology.
    Olovsson, W.
    Uppsala University.
    Wallenius, J.
    Royal Institute of Technology.
    Ab initio simuleringar av materialegenskaper: från grundläggande teori mot design av material2004In: Nytt från NSC, no 19, p. 3-5Article in journal (Other (popular science, discussion, etc.))
  • 7663.
    Abrikosov, Igor
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, The Institute of Technology. NUST MISIS, Russia.
    Ponomareva, A. V.
    NUST MISIS, Russia.
    Nikonov, A. Yu.
    National Research Tomsk State University, Russia; SB RAS, Russia.
    Zharmukhambetova, A. M.
    National Research Tomsk State University, Russia.
    Mosyagin, Igor
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, The Institute of Technology. NUST MISIS, Russia.
    Lugovskoy, A. V.
    NUST MISIS, Russia.
    Hellman, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, The Institute of Technology.
    Lind, Hans
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, The Institute of Technology.
    Dmitriev, A. I.
    National Research Tomsk State University, Russia; SB RAS, Russia.
    Barannikova, S. A.
    National Research Tomsk State University, Russia; SB RAS, Russia.
    Theoretical description of pressure-induced phase transitions: a case study of Ti-V alloys2015In: High Pressure Research, ISSN 0895-7959, E-ISSN 1477-2299, Vol. 35, no 1, p. 42-48Article in journal (Refereed)
    Abstract [en]

    We discuss theoretical description of pressure-induced phase transitions by means of first-principles calculations in the framework of density functional theory. We illustrate applications of theoretical tools that allow one to take into account configurational and vibrational disorders, considering Ti-V alloys as a model system. The universality of the first-principles theory allows us to apply it in studies of different phenomena that occur in the Ti-V system upon compression. Besides the transitions between different crystal structures, we discuss isostructural transitions in bcc Ti-V alloys. Moreover, we present arguments for possible electronic transitions in this system, which may explain peculiar behaviour of elastic properties of V upon compression.

  • 7664.
    Abrikosov, Igor
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering. National University of Science and Technology MISIS, Russia.
    Ponomareva, A. V.
    National University of Science and Technology MISIS, Russia.
    Steneteg, Peter
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Barannikova, S. A.
    National University of Science and Technology MISIS, Russia; National Research Tomsk State University, Russia; SB RAS, Russia.
    Alling, Björn
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Recent progress in simulations of the paramagnetic state of magnetic materials2016In: Current opinion in solid state & materials science, ISSN 1359-0286, E-ISSN 1879-0348, Vol. 20, no 2, p. 85-106Article, review/survey (Refereed)
    Abstract [en]

    We review recent developments in the field of first-principles simulations of magnetic materials above the magnetic order disorder transition temperature, focusing mainly on 3d-transition metals, their alloys and compounds. We review theoretical tools, which allow for a description of a system with local moments, which survive, but become disordered in the paramagnetic state, focusing on their advantages and limitations. We discuss applications of these theories for calculations of thermodynamic and mechanical properties of paramagnetic materials. The presented examples include, among others, simulations of phase stability of Fe, Fe-Cr and Fe-Mn alloys, formation energies of vacancies, substitutional and interstitial impurities, as well as their interactions in Fe, calculations of equations of state and elastic moduli for 3d-transition metal alloys and compounds, like CrN and steels. The examples underline the need for a proper treatment of magnetic disorder in these systems. (C) 2015 Elsevier Ltd. All rights reserved.

  • 7665.
    Abrikossov, Alexei
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Biology Education Centre.
    Computer simulations: Orientation of Lysozyme in vacuum under the influence of an electric field2011Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The possibility to orient a protein in space using an external electrical field was studied bymeans of molecular dynamics simulations. To model the possible conditions of an electrospray ionization (ESI) the protein Lysozyme in vacuum was considered under the influence ofdifferent field strengths. The simulations showed three distinct patterns: (1) the protein wasdenaturated when exposed to too strong electrical fields, above 1.5 V/nm; (2) the proteinoriented without being denaturated at field strengths between 0.5 V/nm and 1.5 V/nm (3) theprotein did not orient and did not denaturate if the strength of the field became to low, below0.5 V/nm. Our simulations show that the orientation of the protein in the fields correspondingto the second pattern takes place within time intervals from about 100 ps at 1.5 V/nm to about1 ns at 0.5 V/nm. We therefore predict, that there exists a window of field strengths, which issuitable for orientation of proteins in experimental studies without affecting their structure.The orientation of proteins potentially increases the amount of information that can beobtained from experiments such as single particle imaging. This study will therefore bebeneficial for the development of such modern techniques.

  • 7666.
    Abrikossova, Natalia
    Linköping University, Department of Physics, Chemistry and Biology, Molecular Surface Physics and Nano Science. Linköping University, Faculty of Science & Engineering.
    Investigation of nanoparticle-cell interactions for development of next generation of biocompatible MRI contrast agents2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Progress in synthesis technologies and advances in fundamental understanding of materials with low dimensionality has led to the birth of a new scientific field, nanoscience, and to strong expectations of multiple applications of nanomaterials. The physical properties of small particles are unique, bridging the gap between atoms and molecules, on one side, and bulk materials on the other side. The work presented in this thesis investigates the potential of using magnetic nanoparticles as the next generation of contrast agents for biomedical imaging. The focus is on gadolinium-based nanoparticles and cellular activity including the uptake, morphology and production of reactive oxygen species.

    Gd ion complexes, like Gd chelates, are used today in the clinic, world-wide. However, there is a need for novel agents, with improved contrast capabilities and increased biocompatibility. One avenue in their design is based on crystalline nanoparticles. It allows to reduce the total number of Gd ions needed for an examination. This can be done by nanotechnology, which allows one to improve and fine tune the physico- chemical properties on the nanomaterial in use, and to increase the number of Gd atoms at a specific site that interact with protons and thereby locally increase the signal. In the present work, synthesis, purification and surface modification of crystalline Gd2O3-based nanoparticles have been performed. The nanoparticles are selected on the basis of their physical properties, that is they show enhanced magnetic properties and therefore may be of high potential interest for applications as contrast agents.

    The main synthesis method of Gd2O3 nanoparticles in this work was the modified “polyol” route, followed by purification of as-synthesized DEG-Gd2O3 nanoparticles suspensions. In most cases the purification step involved dialysis of the nanoparticle samples. In this thesis, organosilane were chosen as an exchange agent for further functionalization. Moreover, several paths have been explored for modification of the nanoparticles, including Tb3+ doping and capping with sorbitol.

    Biocompatibility of the newly designed nanoparticles is a prerequisite for their use in medical applications. Its evaluation is a complex process involving a wide range of biological phenomena. A promising path adopted in this work is to study of nanoparticle interactions with isolated blood cells. In this way one could screen nanomaterial prior to animal studies.

    The primary cell type considered in the thesis are polymorphonuclear neutrophils (PMN) which represent a type of the cells of human blood belonging to the granulocyte family of leukocytes. PMNs act as the first defense of the immune system against invading pathogens, which makes them valuable for studies of biocompatibility of newly synthesized nanoparticles. In addition, an immortalized murine alveolar macrophage cell line (MH-S), THP-1 cell line, and Ba/F3 murine bone marrow-derived cell line were considered to investigate the optimization of the cell uptake and to examine the potential of new intracellular contrast agent for magnetic resonance imaging.

    In paper I, the nanoparticles were investigated in a cellular system, as potential probes for visualization and targeting intended for bioimaging applications. The production of reactive oxygen species (ROS) by means of luminol-dependent chemiluminescence from human neutrophils was studied in presence of Gd2O3 nanoparticles. In paper II, a new design of functionalized ultra-small rare earth-based nanoparticles was reported. The synthesis was done using polyol method followed by PEGylation, and dialysis. Supersmall gadolinium oxide (DEG-Gd2O3) nanoparticles, in the range of 3-5 nm were obtained and carefully characterized. Neutrophil activation after exposure to this nanomaterial was studied by means of fluorescence microscopy. In paper III, cell labeling with Gd2O3 nanoparticles in hematopoietic cells was monitored by magnetic resonance imaging (MRI). In paper IV, ultra-small gadolinium oxide nanoparticles doped with terbium ions were synthesized as a potentially bifunctional material with both fluorescent and magnetic contrast agent properties. Paramagnetic behavior was studied. MRI contrast enhancement was received, and the luminescent/ fluorescent property of the particles was attributable to the Tb3+ ion located on the crystal lattice of the Gd2O3 host. Fluorescent labeling of living cells was obtained. In manuscript V, neutrophil granulocytes were investigated with rapid cell signaling communicative processes in time frame of minutes, and their response to cerium-oxide based nanoparticles were monitored using capacitive sensors based on Lab-on-a-chip technology. This showed the potential of label free method used to measure oxidative stress of neutrophil granulocytes. In manuscript VI, investigations of cell-(DEGGd2O3) nanoparticle interactions were carried out. Plain (DEG-Gd2O3) nanoparticles, (DEG-Gd2O3) nanoparticles in presence of sorbitol and (DEG-Gd2O3) nanoparticles capped with sorbitol were studied. Relaxation studies and measurements of the reactive oxygen species production by neutrophils were based on chemiluminescence. Cell morphology was evaluated as a parameter of the nanoparticle induced inflammatory response by means of the fluorescence microscopy.

    The thesis demonstrates high potential of novel Gd2O3-based nanoparticles for development of the next generation contrast agents, that is to find biocompatible compounds with high relaxivity that can be detected at lower doses, and in the future enable targeting to provide great local contrast.

  • 7667.
    Abrikossova, Natalia
    Linköping University, The Department of Physics, Chemistry and Biology.
    In-vitro studier av inflammatorisk svar från helblod och neutrofila granulocyter vid aktivering med nanopartiklar2007Independent thesis Basic level (degree of Bachelor), 10 points / 15 hpStudent thesis
    Abstract [sv]

    Syftet med detta arbete var att studera inflammatoriska effekter i mänskligt helblod och neutrofila granulocyter exponerade och stimulerade av nanopartiklar av gadoliniumoxid. Projektet utreder den toxiska potentialen hos nanopartiklar med olika kemiska och morfologiska egenskaper.

    I experimenten undersöktes cellresponsen hos blodceller exponerade med ofunktionaliserade och funktionaliserade nanopartiklarna. Effekterna av funktionaliserade och ofunktionaliserade nanopartiklarna på aggregation och syreradikalproduktion i helblod och hos neutrofila granulocyter studerades med hjälp av lumi-aggregometri.

    Studier har visat att varken ofunktionaliserade eller funktionaliserade nanopartiklarna ger aggregation i blodet. Syreradikalproduktionen ökar däremot. Resultaten av studier i helblod visar att stimulering med spädnings serier av funktionaliserade nanopartiklar ger mindre frisättning av syreradikaler än spädnings serier med ofunktionaliserade nanopartiklar. Detta bekräftas med studier av morfologiska skillnader i neutrofila granulocyter som var stimulerade med olika typer av nanopartiklar. Detta gjordes med hjälp av fluorescensmikroskopi. Resultaten från studierna tyder på att funktionaliserade nanopartiklar är mindre inflammatoriska än ofunktionaliserade nanopartiklar.

  • 7668.
    Abrikossova, Natalia
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Molecular Surface Physics and Nano Science. Linköping University, Faculty of Science & Engineering.
    Skoglund, Caroline
    Linköping University, Department of Physics, Chemistry and Biology, Molecular Surface Physics and Nano Science. Linköping University, The Institute of Technology.
    Ahrén, Maria
    Linköping University, Department of Physics, Chemistry and Biology, Molecular Surface Physics and Nano Science. Linköping University, Faculty of Science & Engineering.
    Bengtsson, Torbjorn
    University of Örebro, Sweden .
    Uvdal, Kajsa
    Linköping University, Department of Physics, Chemistry and Biology, Molecular Surface Physics and Nano Science. Linköping University, Faculty of Science & Engineering.
    Effects of gadolinium oxide nanoparticles on the oxidative burst from human neutrophil granulocytes2012In: Nanotechnology, ISSN 0957-4484, E-ISSN 1361-6528, Vol. 23, no 27, p. 275101-Article in journal (Refereed)
    Abstract [en]

    We have previously shown that gadolinium oxide (Gd2O3) nanoparticles are promising candidates to be used as contrast agents in magnetic resonance (MR) imaging applications. In this study, these nanoparticles were investigated in a cellular system, as possible probes for visualization and targeting intended for bioimaging applications. We evaluated the impact of the presence of Gd2O3 nanoparticles on the production of reactive oxygen species (ROS) from human neutrophils, by means of luminol-dependent chemiluminescence. Three sets of Gd2O3 nanoparticles were studied, i.e. as synthesized, dialyzed and both PEG-functionalized and dialyzed Gd2O3 nanoparticles. In addition, neutrophil morphology was evaluated by fluorescent staining of the actin cytoskeleton and fluorescence microscopy. We show that surface modification of these nanoparticles with polyethylene glycol (PEG) is essential in order to increase their biocompatibility. We observed that the as synthesized nanoparticles markedly decreased the ROS production from neutrophils challenged with prey (opsonized yeast particles) compared to controls without nanoparticles. After functionalization and dialysis, more moderate inhibitory effects were observed at a corresponding concentration of gadolinium. At lower gadolinium concentration the response was similar to that of the control cells. We suggest that the diethylene glycol (DEG) present in the as synthesized nanoparticle preparation is responsible for the inhibitory effects on the neutrophil oxidative burst. Indeed, in the present study we also show that even a low concentration of DEG, 0.3%, severely inhibits neutrophil function. In summary, the low cellular response upon PEG-functionalized Gd2O3 nanoparticle exposure indicates that these nanoparticles are promising candidates for MR-imaging purposes.

  • 7669.
    Abrikossova, Natalia
    et al.
    Division of Molecular Surface Physics and Nanoscience, Department of Physics, Chemistry and Biology, Linköping University, Linköping, Sweden .
    Skoglund, Caroline
    Division of Molecular Surface Physics and Nanoscience, Department of Physics, Chemistry and Biology, Linköping University, Linköping, Sweden; Division of Clinical Medicine, Department of Biomedicine, Örebro University, Örebro, Sweden.
    Ahrén, Maria
    Division of Molecular Surface Physics and Nanoscience, Department of Physics, Chemistry and Biology, Linköping University, Linköping, Sweden.
    Bengtsson, Torbjörn
    Örebro University, School of Health and Medical Sciences, Örebro University, Sweden. Division of Clinical Medicine, Department of Biomedicine, School of Health and Medical Sciences, Örebro University, Örebro, Sweden.
    Uvdal, Kajsa
    Division of Molecular Surface Physics and Nanoscience, Department of Physics, Chemistry and Biology, Linköping University, Linköping, Sweden.
    Effects of gadolinium oxide nanoparticles on the oxidative burst from human neutrophil granulocytes2012In: Nanotechnology, ISSN 0957-4484, E-ISSN 1361-6528, Vol. 23, no 27, article id 275101Article in journal (Refereed)
    Abstract [en]

    We have previously shown that gadolinium oxide (Gd2O3) nanoparticles are promising candidates to be used as contrast agents in magnetic resonance (MR) imaging applications. In this study, these nanoparticles were investigated in a cellular system, as possible probes for visualization and targeting intended for bioimaging applications. We evaluated the impact of the presence of Gd2O3 nanoparticles on the production of reactive oxygen species (ROS) from human neutrophils, by means of luminol-dependent chemiluminescence. Three sets of Gd2O3 nanoparticles were studied, i.e. as synthesized, dialyzed and both PEG-functionalized and dialyzed Gd2O3 nanoparticles. In addition, neutrophil morphology was evaluated by fluorescent staining of the actin cytoskeleton and fluorescence microscopy. We show that surface modification of these nanoparticles with polyethylene glycol (PEG) is essential in order to increase their biocompatibility. We observed that the as synthesized nanoparticles markedly decreased the ROS production from neutrophils challenged with prey (opsonized yeast particles) compared to controls without nanoparticles. After functionalization and dialysis, more moderate inhibitory effects were observed at a corresponding concentration of gadolinium. At lower gadolinium concentration the response was similar to that of the control cells. We suggest that the diethylene glycol (DEG) present in the as synthesized nanoparticle preparation is responsible for the inhibitory effects on the neutrophil oxidative burst. Indeed, in the present study we also show that even a low concentration of DEG, 0.3%, severely inhibits neutrophil function. In summary, the low cellular response upon PEG-functionalized Gd2O3 nanoparticle exposure indicates that these nanoparticles are promising candidates for MR-imaging purposes.

  • 7670.
    Abril, Claudia
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences.
    Seismicity and crustal structure in Iceland2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The main goal of this Ph.D. thesis is to improve locations of earthquake hypocenters and to resolve heterogeneous crustal structure and its effects on travel times. The data and case studies are drawn from the Icelandic national SIL network and the temporary NICE project deploy-ment in the Tjörnes Fracture Zone. Iceland presents complex tectonics and active volcanism, consequences of its position astride the Mid-Atlantic Ridge between the European and North American plates and on top of a melting anomaly in the mantle below. Studies focused on characterizing the seismicity and the crustal structure are prerequisites for further seismologi-cal studies in Iceland, e.g., on seismic sources, the evolution of volcanic systems, activity on seismic faults and seismic hazard, among others.

    Different methods have been explored. First, we estimated empirically travel-time functions of seismic waves and their uncertainties for 65 stations in the Icelandic permanent network (SIL) using arrival times. The estimated travel-time functions and uncertainties were used to relocate the complete catalog applying a nested-search algorithm to this non-linear problem. The clearest changes in locations compared to the SIL solutions were obtained in the peripheral areas of the network, in particular in the Tjörnes Fracture Zone (North Iceland) and on the Reykjanes Peninsula (South Iceland).

    Relocations with empirical travel times were used complementary with constrained earth-quake relocation and the collapsing methods of Li et al. [2016] to study the seismicity in the Hengill area (South Iceland). Patterns in the seismicity in the final locations reproduce lin-eations previously found in relative relocations in the area. The brittle-ductile transition was estimated, obtaining a smaller depth in the northern part of the region, dominated by volcanic processes, compared with the south, controlled by tectonic processes. Furthermore, the Hengill fissure swarm that hosts two large geothermal power plants, was found to have deeper penetrat-ing earthquakes than adjacent volcanic areas, presumably because it is more effectively cooled.

    Local earthquake tomography was used to solve simultaneously for earthquake location and velocity structure in the Tjörnes Fracture Zone, using data from the temporary network installed during the North ICeland Experiment, and data from the permanent SIL network. 3-D velocity models for P- and S-waves were obtained for the area and used to relocate the complete SIL catalog. The results demonstrate significant structures associated with the different branches of this complex transform region, e.g. low velocities along the Husavík-Flatey Fault (HFF), penetrating to about 10 km depth. Low Vp/Vs ratios were also mapped at depth along the HFF indicating presence of highly compressible fluids in the middle crust. In general, the seismicity pattern was shifted towards the surface from SIL locations and clarified in its lateral distribution. This highlighted a zone of concentrated deformation in the Tjörnes Microplate, which intersections with the two main strands of the overall zone coincide with changes in their geometry and character.

  • 7671.
    Abril, Claudia
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Geophysics.
    Gudmundsson, Ólafur
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Geophysics.
    Relocating earthquakes with empirical traveltimes2018In: Geophysical Journal International, ISSN 0956-540X, E-ISSN 1365-246X, Vol. 214, no 3, p. 2098-2114Article in journal (Refereed)
    Abstract [en]

    A strategy is proposed to incorporate effects of 3-D velocity variations on earthquake locationsusing empirical traveltimes (ETTs). Traveltime residuals are interpolated from those predictedusing a 1-D velocity reference, mapped on to the hypocentres of corresponding earthquakesfor each station in a network. First, station corrections are computed by averaging the residualsover a fixed scale. Then, summary-ray variograms are used to estimate uncertainty and that,in turn, is used to tune a local fit to neighbouring residuals to refine the corrections. Resulting3-D traveltime estimates are then used as a description of the forward problem in a nonlineargrid-search relocation. Data are weighted according to the estimated uncertainty. Data fromthe Icelandic Southern Iceland Lowlands (SIL) national seismic network are used to test thestrategy. ETTs are estimated forP- andS-waves at 65 stations in the SIL network, basedon four million arrival time readings of 300.000 events registered between 1990 and 2012.ETTs are strongly correlated for the two wave types. The spatial variations of the predictedcorrections are consistently comparable or somewhat less forS-waves thanP-waves. Thisfeature suggests variations of theVP/VSratio in the Icelandic crust. Error estimates are alsostrongly correlated for the two wave types and between nearby stations. Relocations aretested by comparison with explosions and small populations of well-located events withindenser subnetworks. Relocations result in modestly enhanced clustering of explosions andearthquakes and significantly improved depth estimates. Estimates of the random relocationerror are statistically better behaved than those of the SIL system. They are in general reduced,as is expected since 3-D heterogeneity is now partly taken into account.

  • 7672.
    Abril, Claudia
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences.
    Mai, Martin
    King Abdullah University of Science and Technology.
    Jonsson, Sigurjon
    King Abdullah University of Science and Technology.
    Ground-motion simulations around the Husavik-Flatey Fault, North IcelandManuscript (preprint) (Other academic)
  • 7673.
    Abril, Claudia
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences.
    Tryggvason, Ari
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Geophysics.
    Gudmundsson, Ólafur
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Geophysics.
    Steffen, Rebekka
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Geophysics.
    Local earthquake tomography and earthquake relocation in the Tjörnes Fracture Zone (North Iceland)Manuscript (preprint) (Other academic)
  • 7674.
    Abril, Daniel
    et al.
    IIIA, Institut d'Investigació en Intelligència Artificial – CSIC, Consejo Superior de Investigaciones Científicas, Bellaterra, Spain / UAB, Universitat Autónoma de Barcelona, Bellaterra, Spain.
    Navarro-Arribas, Guillermo
    DEIC, Dep. Enginyeria de la Informació i de les Comunicacions, UAB, Universitat Autònoma de Barcelona, Bellaterra, Spain.
    Torra, Vicenç
    University of Skövde, School of Informatics. University of Skövde, The Informatics Research Centre. IIIA, Institut d'Investigació en Intelligència Artificial – CSIC, Consejo Superior de Investigaciones Científicas, Bellaterra, Spain.
    Spherical Microaggregation: Anonymizing Sparse Vector Spaces2015In: Computers & security (Print), ISSN 0167-4048, E-ISSN 1872-6208, Vol. 49, p. 28-44Article in journal (Refereed)
    Abstract [en]

    Unstructured texts are a very popular data type and still widely unexplored in the privacy preserving data mining field. We consider the problem of providing public information about a set of confidential documents. To that end we have developed a method to protect a Vector Space Model (VSM), to make it public even if the documents it represents are private. This method is inspired by microaggregation, a popular protection method from statistical disclosure control, and adapted to work with sparse and high dimensional data sets.

  • 7675.
    Abril, Daniel
    et al.
    IIIA, Institut d'Investigació en Intel·ligència Artificial, CSIC, Consejo Superior de Investigaciones Científicas, Campus UAB s/n, Bellaterra, Spain / UAB, Universitat Autònoma de Barcelona, Campus UAB s/n, Bellaterra, Spain.
    Torra, Vicenç
    University of Skövde, School of Informatics. University of Skövde, The Informatics Research Centre. IIIA, Institut d'Investigació en Intel·ligència Artificial, CSIC, Consejo Superior de Investigaciones Científicas, Campus UAB s/n, Bellaterra, Spain.
    Navarro-Arribas, Guillermo
    DEIC, Dep. Enginyeria de la Informació i de les Comunicacions, UAB, Universitat Autònoma de Barcelona, Campus UAB s/n, Bellaterra, Spain.
    Supervised Learning Using a Symmetric Bilinear Form for Record Linkage2015In: Information Fusion, ISSN 1566-2535, E-ISSN 1872-6305, Vol. 26, p. 144-153Article in journal (Refereed)
    Abstract [en]

    Record Linkage is used to link records of two different files corresponding to the same individuals. These algorithms are used for database integration. In data privacy, these algorithms are used to evaluate the disclosure risk of a protected data set by linking records that belong to the same individual. The degree of success when linking the original (unprotected data) with the protected data gives an estimation of the disclosure risk.

    In this paper we propose a new parameterized aggregation operator and a supervised learning method for disclosure risk assessment. The parameterized operator is a symmetric bilinear form and the supervised learning method is formalized as an optimization problem. The target of the optimization problem is to find the values of the aggregation parameters that maximize the number of re-identification (or correct links). We evaluate and compare our proposal with other non-parametrized variations of record linkage, such as those using the Mahalanobis distance and the Euclidean distance (one of the most used approaches for this purpose). Additionally, we also compare it with other previously presented parameterized aggregation operators for record linkage such as the weighted mean and the Choquet integral. From these comparisons we show how the proposed aggregation operator is able to overcome or at least achieve similar results than the other parameterized operators. We also study which are the necessary optimization problem conditions to consider the described aggregation functions as metric functions.

  • 7676.
    Abril López, Raimundo
    et al.
    University of Skövde, School of Technology and Society.
    Huertas Molina, Pablo
    University of Skövde, School of Technology and Society.
    González Zuheros, Rocío
    University of Skövde, School of Technology and Society.
    STRUCTURAL ANALYSIS OF A WASHING MACHINE THROUGH ITS LOADING CASES: REDESIGN OF THE TRIPOD AND THE FRONT COVER2011Independent thesis Basic level (degree of Bachelor), 15 credits / 22,5 HE creditsStudent thesis
    Abstract [en]

    This project thesis is developed in collaboration with the mechanical department at University of Skövde, and it is focused in the determination of different loading cases and the application of their results to the optimization of two parts of a washing machine.

     

    The first step in this report is to obtain a numerical model of a washing machine. It includes the assembly in a mechanical software program (Abaqus), and the assignment of the specific boundary conditions and material properties for the problem. Simulation parameters such as mesh size; types of elements, and number of iterations used in the calculations will also be decided.

     

    A study of the different loading cases is carried out with the intention of having a general view of the problem and selecting four specific cases for its application to the reconstruction of the aimed parts (tripod and front cover). This study includes the calculation of the worst relative angle between the tripod and the resultant force for two opposite loads inside the drum. This angle results to be 35º between the arm and the direction of the resultant force.

     

    Through the application of these different loading conditions to this model, the mechanical behaviour of the parts will be obtained and this information will be used in the reconstruction. By mechanical behaviour it is meant to know the maximum level of stress (tension, compression and shear), and deformation (displacement and strain).

     

    Once it is well known which are the most suffering points of the tripod and in the front cover, several different new shapes are created. The parameters considered in this reconstruction were the decrease of volume, the reduction of the level of stress and the deformations. Two of these shapes are chosen and tested in the numerical model, as a checkout.

     

    Finally all these results are presented to the University of Skövde for possible future use.

  • 7677.
    Abril-Ojeda, Galo
    Stockholm University.
    The role of disaster relief for long-term development in LDCs: with special reference to Guatemala after the 1976 earthquake1982Doctoral thesis, monograph (Other academic)
  • 7678.
    Abring, Cecilia
    et al.
    Linköping University, Department of Management and Engineering, Business Administration. Linköping University, Faculty of Arts and Sciences.
    Eriksson, Madeleine
    Linköping University, Department of Management and Engineering, Business Administration. Linköping University, Faculty of Arts and Sciences.
    Transaktionsexponerade kassaflöden: En kvalitativ studie om hur styrdokument reglerar den praktiska hanteringen av transaktionsexponerade kassaflöden2015Independent thesis Advanced level (degree of Master (One Year)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Background: As a result of increased international trading, adequate management of transaction exposure has become more important. Foreign currency cash flows are associated with different risks and thus give cause to distinct transaction exposure with overseas trading. Previous research advocates that management of transaction exposure is controlled through policy documents and we have identified a lack of research in how policy documents of Swedish firms are designed.

    Problem: To what extent is previous research agreeing with how Swedish firms have developed policy documents for managing transaction exposure of different foreign currency cash flows?

    Aim: The aim of the study is, compared to what previous research advocates, to examine and analyze how policy documents for managing transaction exposure are designed within the Swedish firms. The study also aims to analyze the differences in the policy document for the transaction exposure in different foreign currency cash flows, as well as the factors that give reasons to possible deviations.

    Conclusions: The findings of the study indicate a clear congruence between previous research and established practices of how policy documents for managing transaction exposure are designed in Swedish firms. Policy documents are comprehensive in their design; regulate the risk management strategy but not the management procedures. Even though the actual management of transaction exposure of different foreign currency cash flows indicates significant discrepancies, the policy document doesn’t regulate any of them. Giving reason for a different management are: factors related to the foreign exchange market characteristics, company-specific factors and other influencing market factors.Contribution: The study contributes to a better understanding and clearer differentiation of how Swedish firms control the management of transaction exposure, from a business perspective. Moreover, the study intends to give rise to the interest in how and on which grounds companies differently control the management of transaction exposure of different foreign currency cash flows.

  • 7679. Abrink, M
    et al.
    Gobl, Anders
    Uppsala University, Medicinska vetenskapsområdet, Faculty of Medicine, Department of Medical Sciences.
    Huang, R
    Nilsson, K
    Hellman, L
    The human cell lines U-937, THP-1 and MonoMac 6, represent relatively immature cells of the monocyte cell lineage1994In: Leukemia, Vol. 8, p. 1579-Article in journal (Refereed)
  • 7680. Abrink, M
    et al.
    Larsson, E
    Uppsala University, Medicinska vetenskapsområdet, Faculty of Medicine, Department of Genetics and Pathology.
    Hellman, L
    Demethylation of ERV3, an endogenous retrovirus regulating the Kruppel related Zinc finger gene H-plk, in several human cell lines arrested during early monocytic development.1998In: DNA and Cell Biology, Vol. 17, p. 17-Article in journal (Refereed)
  • 7681.
    Abrink, M
    et al.
    Uppsala University, Medicinska vetenskapsområdet, Faculty of Medicine, Department of Medical Biochemistry and Microbiology.
    Larsson, E
    Hellman, L
    Uppsala University, Medicinska vetenskapsområdet, Faculty of Medicine, Department of Medical Biochemistry and Microbiology.
    Demethylation of ERV3, anendogenous retrovirus regulating a krüppel related zinc finger gene H-plk,in several human cell lines arrested during early monocyte development.1998In: DNA and Cell Biology, Vol. 17, p. 27-Article in journal (Refereed)
  • 7682.
    Abrink, Magnus
    et al.
    Uppsala University, Medicinska vetenskapsområdet, Faculty of Medicine, Department of Medical Biochemistry and Microbiology.
    Larsson, Erik
    Department of Genetics and Pathology.
    Gobl, Anders
    Department of Medical Sciences.
    Hellman, Lars
    Uppsala University, Medicinska vetenskapsområdet, Faculty of Medicine, Department of Medical Biochemistry and Microbiology.
    Expression of lactoferrin in the kidney:implications for innate immunity and iron metabolism2000In: Kidney Int, Vol. 57, p. 2004-Article in journal (Refereed)
  • 7683.
    Abrishambaf, Reza
    et al.
    Department of Engineering Technology, Miami University, Hamilton, OH.
    Bal, Mert
    Department of Engineering Technology, Miami University, Hamilton, OH.
    Vyatkin, Valeriy
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Distributed home automation system based on IEC61499 function blocks and wireless sensor networks2017In: Proceedings of the IEEE International Conference on Industrial Technology, Piscataway, NJ: Institute of Electrical and Electronics Engineers (IEEE), 2017, p. 1354-1359, article id 7915561Conference paper (Refereed)
    Abstract [en]

    In this paper, a distributed home automation system will be demonstrated. Traditional systems are based on a central controller where all the decisions are made. The proposed control architecture is a solution to overcome the problems such as the lack of flexibility and re-configurability that most of the conventional systems have. This has been achieved by employing a method based on the new IEC 61499 function block standard, which is proposed for distributed control systems. This paper also proposes a wireless sensor network as the system infrastructure in addition to the function blocks in order to implement the Internet-of-Things technology into the area of home automation as a solution for distributed monitoring and control. The proposed system has been implemented in both Cyber (nxtControl) and Physical (Contiki-OS) level to show the applicability of the solution

  • 7684.
    Abrishami, Mahdi
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Dynamic Link Flow Estimation according to Historical Travel Times2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Vast application of ITS and the availability of numerous on-road detection devices has resulted in variety of alternative data sources to be exploited and used in the field of traffic modelling. In this thesis, historical travel times, as an alternative data source, is employed on the developed method to perform dynamic network loading. The developed method, referred to as DNLTT, uses the share of each route available in the route choice set from the initial demand, as well as link travel times to perform the network loading. The output of the algorithm is time-dependent link flows. DNLTT is applied on Stockholm transportation network, where it is expected to have variation in link travel times in different time-periods, due to network congestion. In order to calculate the route shares, a time-sliced OD matrix is used. The historical travel times and the routes in the route choice set are extracted from an existing route planning tool. An available logit model, which considers the route travel time as the only logit parameter, is used for the route share calculation and the network loading is performed according to 2 different methods of DNLTT and DL. The evaluation of results is done for a toy network, where there happen different network states in different time-periods. Furthermore, the model output from Stockholm case study is analyzed and evaluated. The dynamic behavior of DNLTT is studied by analysis of link flows in different time-periods. Furthermore, the resulting link flows from both network loading methods are compared against observed link flows from radar sensors and the statistical analysis of link flows is performed accordingly. DNLTT exhibits a better performance on the toy network compared to DL, where the increasing link travel times cause the link flows to decline in different time-periods. However, the output of the developed method does not resemble the observed link flows for the investigated links in Stockholm case study. It is strongly believed, that the performance of DNLTT on the investigated transportation network potentially improves, in case the historical travel times better resemble the network dynamics. In addition to a more reliable data set, an OD adjustment process in all the time-periods is believed to generate better model output.

  • 7685.
    Abro, Mehwish
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Modelling the exfoliation of graphite for production of graphene2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The aim of my thesis is to make a theoretical model of data obtained from liquid-phase exfoliation of graphene. The production of graphene in the liquid phase exfoliation is a cost efficient method One part of this work is devotedto learn the method of production of graphene by the shear mixing technique from the graphite and to estimate some important parameters which are crucial for the process. Other part of my work is based on studying the liquid-phase exfoliation mechanism of graphene through ultrasonication technique. This method is time consuming as compared to shearmixing.

  • 7686.
    Abromaitis, V.
    et al.
    Kaunas Univ Technol, Lithuania ; Wetsus, European Ctr Excellence Sustainable Water Technol, Netherlands.
    Racys, V.
    Kaunas Univ Technol, Lithuania.
    van der Marel, P.
    WLN, Netherlands.
    Ni, Gaofeng
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Dopson, Mark
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Wolthuizen, A. L.
    Wageningen Univ, Netherlands.
    Meulepas, R. J. W.
    Wetsus, European Ctr Excellence Sustainable Water Technol, Netherlands.
    Effect of shear stress and carbon surface roughness on bioregeneration and performance of suspended versus attached biomass in metoprolol-loaded biological activated carbon systems2017In: Chemical Engineering Journal, ISSN 1385-8947, E-ISSN 1873-3212, Vol. 317, p. 503-511Article in journal (Refereed)
    Abstract [en]

    The bioregeneration of activated carbon (AC) in biological activated carbon (BAC) systems is limited by sorption-desorption hysteresis and transport between the adsorbent and biomass. In this study, we investigated these limitations and whether a biofilm covering the AC surface is required. Consequently, BAC reactors were operated at different shear stress and AC surface smoothness, since this may affect biofilm formation. The experiments were carried out in BAC and blank reactors treating synthetic wastewater containing the pharmaceutical metoprolol. After start-up, all reactors removed metoprolol completely; however, after 840 h the removal dropped due to saturation of the AC. In the blank reactors, the removal dropped to 0% while in the BAC reactors removal recovered to >99%, due to increased biological activity. During the initial phase, the metoprolol was adsorbed, rather than biodegraded. At the end, the AC from the BAC reactors had higher pore volume and sorption capacity than from the blank reactors, showing that the AC had been bioregenerated. At high shear (G = 25 s(-1)), the rough AC granules (R-a = 13 mu m) were covered with a 50-400 gm thick biofilm and the total protein content of the biofilm was 2.6 mg/gAC, while at lower shear (G = 8.8 s(-1)) the rough AC granules were only partly covered. The biofilm formation at lower shear (G = 8.8 s(-1)) on smooth AC granules (R-a = 1.6 mu m) was negligible. However, due to the presence of suspended biomass the reactor performance or bioregeneration were not reduced. This showed that direct contact between the AC and biomass was not essential in mixed BAC systems. The microbial analyses of the suspended biomass and the biofilm on AC surface indicated that metoprolol was mainly biodegraded in suspension. (C) 2017 Elsevier B.V. All rights reserved.

  • 7687.
    Abrouk, Michael
    et al.
    Institute of Experimental Botany, Centre of the Region Hana for Biotechnological and Agricultural Research, Olomouc, Czech Republic.
    Balcarkova, Barbora
    Institute of Experimental Botany, Centre of the Region Hana for Biotechnological and Agricultural Research, Olomouc, Czech Republic.
    Simkova, Hana
    Institute of Experimental Botany, Centre of the Region Hana for Biotechnological and Agricultural Research, Olomouc, Czech Republic.
    Kominkova, Eva
    Institute of Experimental Botany, Centre of the Region Hana for Biotechnological and Agricultural Research, Olomouc, Czech Republic.
    Martis, Mihaela-Maria
    Linköping University, Department of Clinical and Experimental Medicine, Division of Cell Biology. Linköping University, Faculty of Medicine and Health Sciences. Institute for Bioinformatics and Systems Biology, Helmholtz Center Munich, Neuherberg, Germany.
    Jakobson, Irena
    Department of Gene Technology, Tallinn University of Technology, Akadeemia tee 15, Tallinn 19086, Estonia.
    Timofejeva, Ljudmilla
    Department of Gene Technology, Tallinn University of Technology, Akadeemia tee 15, Tallinn 19086, Estonia.
    Rey, Elodie
    Institute of Experimental Botany, Centre of the Region Hana for Biotechnological and Agricultural Research, Olomouc, Czech Republic.
    Vrana, Jan
    Institute of Experimental Botany, Centre of the Region Hana for Biotechnological and Agricultural Research, Olomouc, Czech Republic.
    Kilian, Andrzej
    Diversity Arrays Technology Pty Ltd, Yarralumla, ACT2600, Australia.
    Järve, Kadri
    Department of Gene Technology, Tallinn University of Technology, Akadeemia tee 15, Tallinn 19086, Estonia.
    Dolezel, Jaroslav
    Institute of Experimental Botany, Centre of the Region Hana for Biotechnological and Agricultural Research, Olomouc, Czech Republic.
    Valarik, Miroslav
    Institute of Experimental Botany, Centre of the Region Hana for Biotechnological and Agricultural Research, Olomouc, Czech Republic.
    The in silico identification and characterization of a bread wheat/Triticum militinae introgression line: Characterization of alien introgression in wheat2017In: Plant Biotechnology Journal, ISSN 1467-7644, E-ISSN 1467-7652, Vol. 15, no 2, p. 249-256Article in journal (Refereed)
    Abstract [en]

    The capacity of the bread wheat (Triticum aestivum) genome to tolerate introgression from related genomes can be exploited for wheat improvement. A resistance to powdery mildew expressed by a derivative of the cross bread wheat cv. Tähti ⨯ T. militinae (Tm) is known to be due to the incorporation of a Tm segment into the long arm of chromosome 4A. Here, a newly developed in silico method termed RICh (rearrangement identification and characterization) has been applied to characterize the introgression. A virtual gene order, assembled using the GenomeZipper approach, was obtained for the native copy of chromosome 4A; it incorporated 570 4A DArTseq markers to produce a zipper comprising 2,132 loci. A comparison between the native and introgressed forms of the 4AL chromosome arm showed that the introgressed region is located at the distal part of the arm. The Tm segment, derived from chromosome 7G, harbors 131 homoeologs out of the 357 genes present on the corresponding region of Chinese Spring 4AL. The estimated number of Tm genes transferred along with the disease resistance gene was 169. Characterizing the introgression's position, gene content and internal gene order should facilitate not only gene isolation, but may also be informative with respect to chromatin structure and behavior studies.

  • 7688.
    Abrzid, Muhamad
    Södertörn University College, School of Business Studies.
    Godstransport mellan kvalitets- och priskonkurrens2010Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
  • 7689.
    Abrèu, Lorenny
    et al.
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Hodzic, Amela
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Hemlöshet: En studie av missbruk och stämpling2009Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

     

    Med denna studie ville vi belysa hur före detta hemlösa upplevt de sociala myndigheternas insatser samt vilken hjälp de fick under deras tid som hemlösa. I studien medverkade åtta personer som tidigare varit hemlösa. Vi har tillämpat teorier från sociologer så som Erving Goffman (Stigma), Howard Becker (avvikarkarriären) samt Johan Cullberg (kris och utveckling). Detta för att kunna belysa empirin som framkom i studien. I studien har vi använt oss av sex artiklar från tidigare forskning som handlade om hemlöshet. Detta delades upp i fyra olika kategorier och utifrån dessa har vi tillämpat vår empiri. Denna studie utgår från en kvalitativ metod med en hermeneutisk forskningstradition.

    Resultatet i studien visade att hälften utav respondenterna var nöjda med de insatser de fick från de sociala myndigheterna. Vi kunde även se att motivation till förändring inte endast var ett krav från de sociala myndigheterna utan genom motivation fick respondenterna de resurser de var i behov av. Andra hälften var inte nöjda med myndigheternas insatser då en del kraven var alldeles för många och svåra att uppnå. Samtliga respondenter betonade frivilliga organisationers betydelse som bidrog till att respondenterna kunde ta sig ur hemlösheten.

  • 7690. Abs, Roger
    et al.
    Feldt-Rasmussen, Ulla
    Mattsson, Anders F
    Monson, John P
    Bengtsson, Bengt-Ake
    Goth, M I
    Wilton, Patrick
    Koltowska-Häggström, Maria
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmacy.
    Determinants of cardiovascular risk in 2589 hypopituitary GH-deficient adults - a KIMS database analysis.2006In: European Journal of Endocrinology, ISSN 0804-4643, E-ISSN 1479-683X, Vol. 155, no 1, p. 79-90Article in journal (Refereed)
    Abstract [en]

    Objective: The aim of the present study was to clarify the relationship between GH deficiency (GHD) andsome cardiovascular risk factors and to analyse the effect of GH replacement therapy in a large numberof patients over a prolonged period of time.Design: Data for analysis were retrieved from KIMS (Pfizer International Metabolic Database). Serumconcentrations of total cholesterol, high-density lipoprotein (HDL)-cholesterol, low-density lipoprotein(LDL)-cholesterol and triglycerides were obtained from 2589 patients at baseline and from 1206patients after 1 and 2 years of GH replacement therapy. Body mass index (BMI), waist and hip, restingblood pressure and body composition were also measured.Results: At baseline, the unfavourable effects of GHD were most obvious in the lipid profiledemonstrating elevated mean total and LDL-cholesterol, in the increased waist circumference and theelevated BMI. The cholesterol concentration, BMI and body composition were significantly adverselyaffected by a number of factors, including age, sex and the use of anti-epileptic drugs. The therapeuticeffect of GH was essentially uniform across the whole population. GH replacement reduced significantlythe mean total and LDL-cholesterol, the waist circumference and the fat mass and was maintainedduring 2 years.Conclusions: This analysis of a large number of patients confirmed that GHD adults present with anincreased cardiovascular risk. The sustained improvement of the adverse lipid profile and bodycomposition suggests that GH replacement therapy may reduce the risk of cardiovascular disease andthe premature mortality seen in hypopituitary patients with untreated GHD.

  • 7691. Abs, Roger
    et al.
    Mattsson, Anders F
    Bengtsson, Bengt-Ke
    Feldt-Rasmussen, Ulla
    Goth, Miklos I
    Koltowska-Häggström, Maria
    Uppsala University, Medicinska vetenskapsområdet, Faculty of Pharmacy, Department of Pharmacy.
    Monson, John P
    Verhelst, Johan
    Wilton, Patrick
    Isolated growth hormone (GH) deficiency in adult patients: Baseline clinical characteristics and responses to GH replacement in comparison with hypopituitary patients. A sub-analysis of the KIMS database.2005In: Growth Horm IGF Res, ISSN 1096-6374, Vol. 15, no 5, p. 349-59Article in journal (Refereed)
  • 7692.
    Absalyamova, Viktoriya
    Dalarna University, School of Technology and Business Studies, Mechanical Engineering.
    Energy Analysis within Industrial Hydraulics and Correspondent Solar PV System Design2010Independent thesis Advanced level (degree of Master (Two Years))Student thesis
    Abstract [en]

    Energy efficiency and renewable energy use are two main priorities leading to industrial sustainability nowadays according to European Steel Technology Platform (ESTP). Modernization efforts can be done by industries to improve energy consumptions of the production lines. These days, steel making industrial applications are energy and emission intensive. It was estimated that over the past years, energy consumption and corresponding CO2 generation has increased steadily reaching approximately 338.15 parts per million in august 2010 [1]. These kinds of facts and statistics have introduced a lot of room for improvement in energy efficiency for industrial applications through modernization and use of renewable energy sources such as solar Photovoltaic Systems (PV).The purpose of this thesis work is to make a preliminary design and simulation of the solar photovoltaic system which would attempt to cover the energy demand of the initial part of the pickling line hydraulic system at the SSAB steel plant. For this purpose, the energy consumptions of this hydraulic system would be studied and evaluated and a general analysis of the hydraulic and control components performance would be done which would yield a proper set of guidelines contributing towards future energy savings. The results of the energy efficiency analysis showed that the initial part of the pickling line hydraulic system worked with a low efficiency of 3.3%. Results of general analysis showed that hydraulic accumulators of 650 liter size should be used by the initial part pickling line system in combination with a one pump delivery of 100 l/min. Based on this, one PV system can deliver energy to an AC motor-pump set covering 17.6% of total energy and another PV system can supply a DC hydraulic pump substituting 26.7% of the demand. The first system used 290 m2 area of the roof and was sized as 40 kWp, the second used 109 m2 and was sized as 15.2 kWp. It was concluded that the reason for the low efficiency was the oversized design of the system. Incremental modernization efforts could help to improve the hydraulic system energy efficiency and make the design of the solar photovoltaic system realistically possible. Two types of PV systems where analyzed in the thesis work. A method was found calculating the load simulation sequence based on the energy efficiency studies to help in the PV system simulations. Hydraulic accumulators integrated into the pickling line worked as energy storage when being charged by the PV system as well.

  • 7693.
    Absetz, Pilvikki
    et al.
    Univ Eastern Finland, Kuopio, Finland;Collaborat Care Syst Finland, Helsinki, Finland.
    Van Olmen, Josefien
    Inst Trop Med, Antwerp, Belgium.
    Alvesson, Helle
    Karolinska Inst, Stockholm, Sweden.
    Delobelle, Peter
    Univ Western Cape, Bellville, South Africa.
    Kasujja, Francis
    Makerere Univ, Kampala, Uganda.
    Guwatudde, David
    Makerere Univ, Kampala, Uganda.
    Puoane, Thandi
    Univ Western Cape, Bellville, South Africa.
    Daivadanam, Meena
    Uppsala University, Disciplinary Domain of Humanities and Social Sciences, Faculty of Social Sciences, Department of Food, Nutrition and Dietetics. Karolinska Inst, Stockholm, Sweden.
    SMART2D: a self-management approach linking health care and community in prevention and management of type 2 diabetes2018In: International Journal of Behavioral Medicine, ISSN 1070-5503, E-ISSN 1532-7558, Vol. 25, p. S113-S114Article in journal (Other academic)
  • 7694.
    Abshir, Hamdiya
    Dalarna University, School of Education, Health and Social Studies, Caring Science/Nursing.
    Användning av information och kommunikationsteknologi för att främja egenvård på distans för patienter med diabetes typ 2 En litteraturöversikt2016Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Introduction: Diabetes Mellitus is a chronic disease that is linked to suffering

    and lack of quality of life. Self-care is essential to reduce the negative

    consequences. Less than half of all patients achieve good self-care. Some of the

    reasons are limited knowledge of diabetes and poor self-care compliance. The

    introduction of ICT in diabetes care was started to improve clinical outcomes and

    quality of life for patients with diabetes type 2. Aim: To describe how information

    and communication technology can promote self-care in distance for patients with

    diabetes mellitus type 2. Methods: Literature study, in which the articles were

    searched in CINAHL, PubMed and Web of Science. Articles included were 15

    articles with a quantitative, qualitative and mixed method. Results: The results

    showed that information and communication technology such as internet,

    computer and mobile phone-based self-care program promoted self-care in patients

    with diabetes type 2 by increasing knowledge, awareness, motivation and

    improving lifestyle change. Conclusion: Information and communication

    technology can facilitate the daily challenges for patients with type 2 diabetes

    because it covers the knowledge gap and increases patient awareness and

    motivation for self-care.

  • 7695.
    Abshir, Layla
    et al.
    Blekinge Institute of Technology, School of Health Science.
    Pettersson, Malin
    Blekinge Institute of Technology, School of Health Science.
    Att vårda personer med fetma: Vårdpersonalens erfarenheter2013Student thesis
    Abstract [sv]

    Bakgrund: Fetma betraktas som ett folkhälsoproblem i många delar av världen och det blir allt vanligare att personer med fetma söker sjukvård. Tidigare forskning har visat att det kan vara en utmaning för vårdpersonalen att erbjuda patienter med fetma en god och säker vård. Dessa utmaningar måste uppmärksammas så att vårdandet för dessa patienter kan förbättras samt förhindra skador på patienter och personal. Syfte: Syftet med studien var att beskriva vårdpersonalens erfarenheter av att vårda personer med fetma. Metod: Det gjordes en litteraturstudie med kvalitativ ansats som baserades på sju vetenskapliga artiklar. Analysen genomfördes utifrån Graneheim och Lundmans tolkning av innehållsanalys. Resultat: Analysen resulterade i två kategorier och fyra undekategorier. Den ena kategorin var Hinder i omgivningen med underkategorierna Utrustningens otillräcklighet och Begränsningar i miljön. Den andra kategorin var Konsekvenser för vårdpersonalen och hade underkategorierna Risk för arbetsskada och Behov av mer personal och tid. Slutsats: Det framkom i studien att utrustning och fysisk miljö visade sig vara otillräcklig och risken för skada på både personal och patient ökade i samband med vårdanet av personer med fetma. Framtida forskning borde fokusera på hur vårdandet av personer med fetma kan förbättras.

  • 7696.
    Abshirini, Ehsan
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment.
    Interaction between rivers and morphology of cities in Sweden2014In: Our common future in urban morphology, Porto: FEUP edições (Faculdade de Engenharia da Universidade do Porto Edicoes), 2014Conference paper (Refereed)
    Abstract [en]

    Rivers as one of the most important topographic factor have played a strategic role not only on the appearance of cities but they also affect the structure and morphology of cities. In this paper I intend to find out the influence of rivers on the morphology of a cities and discuss that how a city in its physical network interacts with a river flowing inside. My study area is river-cities in Sweden in which they have not received much attention in this issue. To this purpose I use space syntax method integrating with geospatial analysis and extract the properties of physical form of cities in terms of global and local integration value, choice value and so on. Comparing the states of presence and absence of rivers in these cities as well as evaluating the effect of rivers on the morphology of areas located in different banks of rivers are also part of interest in this paper. The primary result shows that although a river is not comparable to a city based on size and the area occupied by, it has a significant effect on the form of a city in both global and local properties. In addition, tracking the pattern of river-cities and their interaction to rivers may lead us to interoperate the physical form of these cities in terms of structured and distributed cities.

  • 7697.
    Abshirini, Ehsan
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment.
    Koch, Daniel
    KTH, School of Architecture and the Built Environment (ABE), Architecture, Architectural Design.
    Resilience, space syntax and spatialinterfaces: The case of river cities2017In: A|Z ITU Journal of the Faculty of Architecture, ISSN 1303-7005, Vol. 14, no 1, p. 25-41Article in journal (Refereed)
    Abstract [en]

    Resilience defined as the capacity of a system to manage impacts, keep its efficiency and continue its development has been scrutinized by researchers from different points of view over the past decades. Due to the prominence of resilience in urban planning, this paper intends to find out how the spatial structure of cities deals with disturbances, and if geographical phenomena such as rivers affect the resilience in cities. Using the space syntax methods syntactically analyze the resilience in cities, we innovatively introduce two measures; similarity and sameness. These measures are in relation with the syntactical properties of cities and compare the degree of resilience between different groups. Similarity measures the degree to which each city retains the relative magnitude of its foreground network after a disturbance and sameness is the degree to which each city retains the same segments as its foreground network after a disturbance. Likewise to network resilience studies, we apply different disturbances on cities and explore the reaction of cities to disturbances in terms of size of the foreground network and which segments are parts thereof. We then compare different groups based on these measurements as a method to analyze sameness and similarity. The results show that the resilience, in the way we define it, is different in different cities depending on in which view and based on which parameters we are discussing the resilience. Additionally morphological phenomena such as rivers have a great impact on the structure of cities and in turn on their resilience.

  • 7698.
    Abshirini, Ehsan
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geoinformatics.
    Koch, Daniel
    KTH, School of Architecture and the Built Environment (ABE), Architecture.
    Rivers as integration devices in cities2016In: City, Territory and Architecture, ISSN 0885-7024, E-ISSN 2195-2701, Vol. 3, no 1, p. 1-21Article in journal (Refereed)
    Abstract [en]

    Background: As dynamic systems rivers and cities have been in interaction under changing relations over time, and the morphology of many cities has risen through a long and steady struggle between the city functions and the river system flowing inside. This makes river cities an interesting case to study how the presence of geographical features interacts with spatial morphology in the formation of cities.

    Methods: The basis of this research is enabled by utilizing a novel model for cross-city comparison presented by Hillier in his Santiago keynote in 2012 called a “star model”. This is done on large samples of cities investigating concurrent configurations, as well as how the properties in this star model react to specific forms of disturbance.

    Results: Results illustrate that the foreground network as identified through maximum choice values in cities are more vital to the structure of cities than the bridges. The overall syntactic structure tends to retain its character (degree of distributedness) and the location of its foreground network (which street segments constitute the foreground network) even when bridges are targeted. Furthermore, counter to the initial hypothesis, river cities tend to change less than non-river cities after targeted disturbance of the systems. Finally, the results show that while there is a statistical morphological difference between river cities and non-river cities, this difference is not directly explained through the bridges.

    Conclusion: Integrating space syntax with statistical and geospatial analysis can throw light on the way in which the properties of city networks and urban structure reflect the relative effect of rivers on the morphology of river cities. The paper, finally, contributes through offering one piece of a better perception of the structure of river-cities that can support strategies of river-cities interaction as well as enhance our knowledge on the constraints and limits to that interaction.

  • 7699.
    Abshirini, Ehsan
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Geoinformatics.
    Koch, Daniel
    KTH, School of Architecture and the Built Environment (ABE), Architecture.
    Visibility Analysis, Similarity and Dissimilarity in General Trends of Building Layouts and their Functions2013In: Proceedings of Ninth International Space Syntax Symposium / [ed] Young Ook Kim, Hoon Tae Park, Kyung Wook Seo, Seoul: Sejong University Press , 2013, p. 11:1-11:15Conference paper (Refereed)
    Abstract [en]

    Visibility analysis is one of the key methods in space syntax theory that discusses visual information conveyed to observers from any location in space that is potentially directly visible for the observer without any obstruction. Visibility – simply defined as what we can see – not only affects the spatial function of buildings, but also has visual relation to the perception of buildings by inhabitants and visitors. In this paper we intend to present the result of visibility analysis applied on a sample of building layouts of different sizes and functions from a variety of places of periods. The main aim of this paper is to statistically explore the general trends of building layouts and show if and how visibility properties such as connectivity, clustering coefficient, mean depth, entropy, and integration values can make distinctions among different functions of buildings. Our findings reveal that there are significant correlation coefficients among global properties of visibility in which we consider the mean value of properties, a similarity suggesting that they are not intensively manipulated by architecture. On the other hand, there are correlations although less so than the previous, still significant among local properties of visibility in which we consider the (max-min) value of properties, suggesting that social, cultural or other physical parameters distinguish buildings individually. We also show that functions such as ‘museum’ and ‘veterinary’ are relatively well-clustered, while functions such as ‘ancient’ and ‘shopping’ show high diversity. In addition, using a decision tree model we show that, in our sample, functions such as ‘museum’ and ‘library’ are more predictable rather than functions such as ‘hospital’ and ‘shopping.’ All of these mean that – at least in our sample – the usability and applicability of well-clustered and well-predicted functions have been predominant in shaping their interior spaces; vice versa, in well-diverse and unpredicted functions, the pragmatic solutions of people’s daily life developed in material culture affect the visual properties of their interior spaces.

  • 7700.
    Abshirini, Ehsan
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geoinformatics.
    Koch, Daniel
    KTH, School of Architecture and the Built Environment (ABE), Architecture.
    Legeby, Ann
    KTH, School of Architecture and the Built Environment (ABE), Architecture.
    Flood hazard and its impact on the resilience of cities: An accessibility-based approach to amenities in the city of Gothenburg, Sweden2017In: Proceedings - 11th International Space Syntax Symposium, SSS 2017, Instituto Superior Tecnico, Departamento de Engenharia Civil, Arquitetura e Georrecursos , 2017, p. 36.1-36.15Conference paper (Refereed)
    Abstract [en]

    In the wake of climate change and its impact on increasing the number and intensity of floods, adaptability of cities to and resistance against the flood hazard is critical to retain functionality of the cities. Vulnerability of urban infrastructure and its resilience to flooding from different points of view have been important and worth investigating for experts in different fields of science. Flood hazards as physical phenomena are influenced by form of the cities and thus the magnitude of their impacts can be intensified by urban infrastructures such as street networks and buildings (Bacchin et. al, 2011). In this paper, we aim to develop a method to assess the resilience of a river city (the city of Gothenburg in Sweden), which is prone to flood events, against such disturbances and find out how the city reacts to river floods and to what extent the city retains its accessibility to essential amenities after a flood occurs. To do so, collecting required data; we, firstly, simulate flood inundation with two different return periods (50 and 1000 years) and then the impact areas overlay on the street networks. Evaluating the resilience of the city, syntactic properties of the street networks before and after flooding are measured at different scales. Additionally, accessibility and the minimum distance of the street networks to essential amenities such as healthcare centers, schools and commercial centers, at a medium distance (3 Km) is examined. The results show that flooding influences the city configuration at global scale more than the local scale based on comparison of syntactic properties before and after flooding. However, the results of accessibility and the minimum distance show that the impact of flooding on the functionality of the city is more limited to the riparian areas and the city is not affected globally.

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