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  • 3001.
    Ajello, M.
    et al.
    Clemson Univ, Kinard Lab Phys, Dept Phys & Astron, Clemson, SC 29634 USA..
    Baldini, L.
    Univ Pisa, I-56127 Pisa, Italy.;Ist Nazl Fis Nucl, Sez Pisa, I-56127 Pisa, Italy..
    Barbiellini, G.
    Ist Nazl Fis Nucl, Sez Trieste, I-34127 Trieste, Italy.;Univ Trieste, Dipartimento Fis, I-34127 Trieste, Italy..
    Bastieri, D.
    Ist Nazl Fis Nucl, Sez Padova, I-35131 Padua, Italy.;Univ Padua, Dipartimento Fis & Astron G Galilei, I-35131 Padua, Italy..
    Bellazzini, R.
    Ist Nazl Fis Nucl, Sez Pisa, I-56127 Pisa, Italy..
    Bissaldi, E.
    Univ Politecn Bari, Dipartimento Fis M Merlin, I-70126 Bari, Italy.;Ist Nazl Fis Nucl, Sez Bari, I-70126 Bari, Italy..
    Blandford, R. D.
    Stanford Univ, Kavli Inst Particle Astrophys & Cosmol, WW Hansen Expt Phys Lab, Dept Phys, Stanford, CA 94305 USA.;Stanford Univ, SLAC Natl Accelerator Lab, Stanford, CA 94305 USA..
    Bonino, R.
    Ist Nazl Fis Nucl, Sez Torino, I-10125 Turin, Italy.;Univ Turin, Dipartimento Fis, I-10125 Turin, Italy..
    Bottacini, E.
    Stanford Univ, Kavli Inst Particle Astrophys & Cosmol, WW Hansen Expt Phys Lab, Dept Phys, Stanford, CA 94305 USA.;Stanford Univ, SLAC Natl Accelerator Lab, Stanford, CA 94305 USA..
    Bregeon, J.
    Univ Montpellier, CNRS IN2P3, Lab Univers & Particules Montpellier, F-34095 Montpellier, France..
    Bruel, P.
    CNRS IN2P3, Ecole Polytech, Lab Leprince Ringuet, F-91128 Palaiseau, France..
    Buehler, R.
    DESY, D-15738 Zeuthen, Germany..
    Cameron, R. A.
    Stanford Univ, Kavli Inst Particle Astrophys & Cosmol, WW Hansen Expt Phys Lab, Dept Phys, Stanford, CA 94305 USA..
    Caputo, R.
    CRESST, Greenbelt, MD 20771 USA.;NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA..
    Caraveo, P. A.
    INAF Ist Astrofis Spaziale & Fis Cosm Milano, Via E Bassini 15, I-20133 Milan, Italy..
    Chiaro, G.
    INAF Ist Astrofis Spaziale & Fis Cosm Milano, Via E Bassini 15, I-20133 Milan, Italy..
    Ciprini, S.
    Agenzia Spaziale Italiana, Space Sci Data Ctr, Via Politecn, I-00133 Rome, Italy..
    Cohen-Tanugi, J.
    Univ Montpellier, CNRS IN2P3, Lab Univers & Particules Montpellier, F-34095 Montpellier, France..
    Costantin, D.
    Univ Padua, Dipartimento Fis & Astron G Galilei, I-35131 Padua, Italy..
    D'Ammando, F.
    INAF Ist Radioastron, I-40129 Bologna, Italy.;Univ Bologna, Dipartimento Astron, I-40127 Bologna, Italy..
    de Palma, F.
    Ist Nazl Fis Nucl, Sez Bari, I-70126 Bari, Italy.;Univ Telemat Pegaso, Piazza Trieste & Trento 48, I-80132 Naples, Italy..
    Di Lalla, N.
    Univ Pisa, I-56127 Pisa, Italy.;Ist Nazl Fis Nucl, Sez Pisa, I-56127 Pisa, Italy..
    Di Mauro, M.
    Stanford Univ, Kavli Inst Particle Astrophys & Cosmol, WW Hansen Expt Phys Lab, Dept Phys, Stanford, CA 94305 USA..
    Di Venere, L.
    Univ Politecn Bari, Dipartimento Fis M Merlin, I-70126 Bari, Italy.;Ist Nazl Fis Nucl, Sez Bari, I-70126 Bari, Italy..
    Dominguez, A.
    Univ Complutense Madrid, Grp Altas Energias, E-28040 Madrid, Spain..
    Favuzzi, C.
    Univ Politecn Bari, Dipartimento Fis M Merlin, I-70126 Bari, Italy.;Ist Nazl Fis Nucl, Sez Bari, I-70126 Bari, Italy..
    Franckowiak, A.
    DESY, D-15738 Zeuthen, Germany..
    Fukazawa, Y.
    Hiroshima Univ, Dept Phys Sci, Higashihiroshima, Hiroshima 7398526, Japan..
    Funk, S.
    Friedrich Alexander Univ Erlangen Nurnberg, Erlangen Ctr Astroparticle Phys, Erwin Rommel Str 1, D-91058 Erlangen, Germany..
    Fusco, P.
    Univ Politecn Bari, Dipartimento Fis M Merlin, I-70126 Bari, Italy.;Ist Nazl Fis Nucl, Sez Bari, I-70126 Bari, Italy..
    Gargano, F.
    Ist Nazl Fis Nucl, Sez Bari, I-70126 Bari, Italy..
    Gasparrini, D.
    Agenzia Spaziale Italiana, Space Sci Data Ctr, Via Politecn, I-00133 Rome, Italy.;Ist Nazl Fis Nucl, Sez Perugia, I-06123 Perugia, Italy..
    Giglietto, N.
    Univ Politecn Bari, Dipartimento Fis M Merlin, I-70126 Bari, Italy.;Ist Nazl Fis Nucl, Sez Bari, I-70126 Bari, Italy..
    Giordano, F.
    Univ Politecn Bari, Dipartimento Fis M Merlin, I-70126 Bari, Italy.;Ist Nazl Fis Nucl, Sez Bari, I-70126 Bari, Italy..
    Giroletti, M.
    INAF Ist Radioastron, I-40129 Bologna, Italy..
    Green, D.
    Univ Maryland, Dept Astron, College Pk, MD 20742 USA.;NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA..
    Grenier, I. A.
    Univ Paris Diderot, Lab AIM, CEA IRFU, CNRS,Serv Astrophys,CEA Saclay, F-91191 Gif Sur Yvette, France..
    Guiriec, S.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA.;George Washington Univ, Dept Phys, 725 21st St NW, Washington, DC 20052 USA..
    Holt, C.
    Univ Maryland Baltimore Cty, Dept Phys, Baltimore, MD 21250 USA.;Univ Maryland Baltimore Cty, Ctr Space Sci & Technol, Baltimore, MD 21250 USA..
    Horan, D.
    CNRS IN2P3, Ecole Polytech, Lab Leprince Ringuet, F-91128 Palaiseau, France..
    Johannesson, G.
    Univ Iceland, Sci Inst, IS-107 Reykjavik, Iceland.;NORDITA, Roslagstullsbacken 23, SE-10691 Stockholm, Sweden..
    Kocevski, D.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA..
    Kuss, M.
    Ist Nazl Fis Nucl, Sez Pisa, I-56127 Pisa, Italy..
    La Mura, G.
    Univ Padua, Dipartimento Fis & Astron G Galilei, I-35131 Padua, Italy..
    Larsson, Stefan
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Li, J.
    Inst Space Sci CSICIEEC, Campus UAB,Carrer Magrans S-N, E-08193 Barcelona, Spain..
    Longo, F.
    Ist Nazl Fis Nucl, Sez Trieste, I-34127 Trieste, Italy.;Univ Trieste, Dipartimento Fis, I-34127 Trieste, Italy..
    Loparco, F.
    Univ Politecn Bari, Dipartimento Fis M Merlin, I-70126 Bari, Italy.;Ist Nazl Fis Nucl, Sez Bari, I-70126 Bari, Italy..
    Lubrano, P.
    Ist Nazl Fis Nucl, Sez Perugia, I-06123 Perugia, Italy..
    Magill, J. D.
    Univ Maryland, Dept Astron, College Pk, MD 20742 USA..
    Maldera, S.
    Stanford Univ, SLAC Natl Accelerator Lab, Stanford, CA 94305 USA..
    Manfreda, A.
    Univ Pisa, I-56127 Pisa, Italy..
    Mazziotta, M. N.
    Ist Nazl Fis Nucl, Sez Bari, I-70126 Bari, Italy..
    Michelson, P. F.
    Stanford Univ, Kavli Inst Particle Astrophys & Cosmol, WW Hansen Expt Phys Lab, Dept Phys, Stanford, CA 94305 USA..
    Mizuno, T.
    Hiroshima Univ, Hiroshima Astrophys Sci Ctr, Higashihiroshima, Hiroshima 7398526, Japan..
    Monzani, M. E.
    Stanford Univ, Kavli Inst Particle Astrophys & Cosmol, WW Hansen Expt Phys Lab, Dept Phys, Stanford, CA 94305 USA..
    Morselli, A.
    Ist Nazl Fis Nucl, Sez Roma Tor Vergata, I-00133 Rome, Italy..
    Negro, M.
    Ist Nazl Fis Nucl, Sez Torino, I-10125 Turin, Italy.;Univ Turin, Dipartimento Fis, I-10125 Turin, Italy..
    Nuss, E.
    Univ Montpellier, CNRS IN2P3, Lab Univers & Particules Montpellier, F-34095 Montpellier, France..
    Omodei, N.
    Stanford Univ, Kavli Inst Particle Astrophys & Cosmol, WW Hansen Expt Phys Lab, Dept Phys, Stanford, CA 94305 USA..
    Orienti, M.
    INAF Ist Radioastron, I-40129 Bologna, Italy..
    Orlando, E.
    Stanford Univ, Kavli Inst Particle Astrophys & Cosmol, WW Hansen Expt Phys Lab, Dept Phys, Stanford, CA 94305 USA..
    Paliya, V. S.
    Clemson Univ, Kinard Lab Phys, Dept Phys & Astron, Clemson, SC 29634 USA..
    Perkins, J. S.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA..
    Persic, M.
    Ist Nazl Fis Nucl, Sez Trieste, I-34127 Trieste, Italy.;Ist Nazl Astrofis, Osservatorio Astron Trieste, I-34143 Trieste, Italy..
    Pesce-Rollins, M.
    Ist Nazl Fis Nucl, Sez Pisa, I-56127 Pisa, Italy..
    Piron, F.
    Univ Montpellier, CNRS IN2P3, Lab Univers & Particules Montpellier, F-34095 Montpellier, France..
    Principe, G.
    Friedrich Alexander Univ Erlangen Nurnberg, Erlangen Ctr Astroparticle Phys, Erwin Rommel Str 1, D-91058 Erlangen, Germany..
    Racusin, J. L.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA..
    Raino, S.
    Univ Politecn Bari, Dipartimento Fis M Merlin, I-70126 Bari, Italy.;Ist Nazl Fis Nucl, Sez Bari, I-70126 Bari, Italy..
    Rando, R.
    Ist Nazl Fis Nucl, Sez Padova, I-35131 Padua, Italy.;Univ Padua, Dipartimento Fis & Astron G Galilei, I-35131 Padua, Italy..
    Razzano, M.
    Ist Nazl Fis Nucl, Sez Pisa, I-56127 Pisa, Italy..
    Razzaque, S.
    Univ Johannesburg, Dept Phys, POB 524, ZA-2006 Auckland Pk, South Africa..
    Reimer, A.
    Stanford Univ, Kavli Inst Particle Astrophys & Cosmol, WW Hansen Expt Phys Lab, Dept Phys, Stanford, CA 94305 USA.;Leopold Franzens Univ Innsbruck, Inst Astro & Teilchenphys, A-6020 Innsbruck, Austria.;Leopold Franzens Univ Innsbruck, Inst Theoret Phys, A-6020 Innsbruck, Austria..
    Reimer, O.
    Stanford Univ, Kavli Inst Particle Astrophys & Cosmol, WW Hansen Expt Phys Lab, Dept Phys, Stanford, CA 94305 USA.;Leopold Franzens Univ Innsbruck, Inst Astro & Teilchenphys, A-6020 Innsbruck, Austria.;Leopold Franzens Univ Innsbruck, Inst Theoret Phys, A-6020 Innsbruck, Austria..
    Sgro, C.
    Siskind, E. J.
    NYCB Real Time Comp Inc, Lattingtown, NY 11560 USA..
    Spandre, G.
    Ist Nazl Fis Nucl, Sez Pisa, I-56127 Pisa, Italy..
    Spinelli, P.
    Univ Politecn Bari, Dipartimento Fis M Merlin, I-70126 Bari, Italy.;Ist Nazl Fis Nucl, Sez Bari, I-70126 Bari, Italy..
    Tak, D.
    Univ Maryland, Dept Astron, College Pk, MD 20742 USA..
    Thayer, J. B.
    Stanford Univ, Kavli Inst Particle Astrophys & Cosmol, WW Hansen Expt Phys Lab, Dept Phys, Stanford, CA 94305 USA..
    Torres, D. F.
    ICREA, E-08010 Barcelona, Spain..
    Tosti, G.
    Univ Perugia, Dipartimento Fis, I-06123 Perugia, Italy..
    Valverde, J.
    CNRS IN2P3, Ecole Polytech, Lab Leprince Ringuet, F-91128 Palaiseau, France..
    Vogel, M.
    Calif State Univ Los Angeles, Dept Phys & Astron, Los Angeles, CA 90032 USA..
    Wood, K.
    Praxis Inc, Alexandria, VA 22303 USA.;Naval Res Lab, Washington, DC 20375 USA..
    Investigating the Nature of Late-time High-energy GRB Emission through Joint Fermi/Swift Observations2018In: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 863, no 2, article id 138Article in journal (Refereed)
    Abstract [en]

    We use joint observations by the Swift X-ray Telescope (XRT) and the Fermi Large Area Telescope (LAT) of gamma-ray burst (GRB) afterglows to investigate the nature of the long-lived high-energy emission observed by Fermi LAT. Joint broadband spectral modeling of XRT and LAT data reveals that LAT nondetections of bright X-ray afterglows are consistent with a cooling break in the inferred electron synchrotron spectrum below the LAT and/or XRT energy ranges. Such a break is sufficient to suppress the high-energy emission so as to be below the LAT detection threshold. By contrast, LAT-detected bursts are best fit by a synchrotron spectrum with a cooling break that lies either between or above the XRT and LAT energy ranges. We speculate that the primary difference between GRBs with LAT afterglow detections and the nondetected population may be in the type of circumstellar environment in which these bursts occur, with late-time LAT detections preferentially selecting GRBs that occur in low wind-like circumburst density profiles. Furthermore, we find no evidence of high-energy emission in the LAT-detected population significantly in excess of the flux expected from the electron synchrotron spectrum fit to the observed X-ray emission. The lack of excess emission at high energies could be due to a shocked external medium in which the energy density in the magnetic field is stronger than or comparable to that of the relativistic electrons behind the shock, precluding the production of a dominant synchrotron self-Compton (SSC) component in the LAT energy range. Alternatively, the peak of the SSC emission could be beyond the 0.1-100 GeV energy range considered for this analysis.

  • 3002. Ajello, M
    et al.
    Larsson, Stefan
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics. AlbaNova, Sweden.
    Li, L.
    KTH, School of Engineering Sciences (SCI), Physics. AlbaNova, Sweden.
    Yassine, M.
    et al.,
    DEEP MORPHOLOGICAL AND SPECTRAL STUDY OF THE SNR RCW 86 WITH FERMI-LAT2016In: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 819, no 2, article id 98Article in journal (Refereed)
    Abstract [en]

    RCW 86 is a young supernova remnant (SNR) showing a shell-type structure at several wavelengths and is thought to be an efficient cosmic-ray (CR) accelerator. Earlier Fermi Large Area Telescope results reported the detection of.-ray emission coincident with the position of RCW 86 but its origin (leptonic or hadronic) remained unclear due to the poor statistics. Thanks to 6.5 years of data acquired by the Fermi-LAT and the new event reconstruction Pass 8, we report the significant detection of spatially extended emission coming from RCW 86. The spectrum is described by a power-law function with a very hard photon index (Gamma= 1.42 +/- 0.1(stat) +/- 0.06(syst)) in the 0.1-500 GeV range and an energy flux above 100 MeV of (2.91. 0.8(stat). 0.12(syst)) 10-11 erg cm(-2) s(-1). Gathering all the available multiwavelength (MWL) data, we perform a broadband modeling of the nonthermal emission of RCW 86 to constrain parameters of the nearby medium and bring new hints about the origin of the gamma-ray emission. For the whole SNR, the modeling favors a leptonic scenario in the framework of a two-zone model with an average magnetic field of 10.2 +/- 0.7 mu G and a limit on the maximum energy injected into protons of 2. x. 10(49) erg for a density of 1 cm(-3). In addition, parameter values are derived for the north-east and south-west (SW) regions of RCW 86, providing the first indication of a higher magnetic field in the SW region.

  • 3003. Ajello, M.
    et al.
    Larsson, Stefan
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics. Oskar Klein Centre for Cosmoparticle Physics, Sweden.
    Li, L.
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics. Oskar Klein Centre for Cosmoparticle Physics, Sweden.
    Zimmer, S.
    et al.,
    Search for Spectral Irregularities due to Photon-Axionlike-Particle Oscillations with the Fermi Large Area Telescope2016In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 116, no 16, article id 161101Article in journal (Refereed)
    Abstract [en]

    We report on the search for spectral irregularities induced by oscillations between photons and axionlike-particles (ALPs) in the γ-ray spectrum of NGC 1275, the central galaxy of the Perseus cluster. Using 6 years of Fermi Large Area Telescope data, we find no evidence for ALPs and exclude couplings above 5×10-12 GeV-1 for ALP masses 0.5ma5 neV at 95% confidence. The limits are competitive with the sensitivity of planned laboratory experiments, and, together with other bounds, strongly constrain the possibility that ALPs can reduce the γ-ray opacity of the Universe.

  • 3004.
    Ajmal Khan, Muhammad
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Raza, Rizwan
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Bohn Lima, Raquel
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology. KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Chaudhry, M. Asharf
    Ahmed, E.
    Abbas, Ghazanfar
    Comparative study of the nano-composite electrolytes based on samaria-doped ceria for low temperature solid oxide fuel cells (LT-SOFCs)2013In: International journal of hydrogen energy, ISSN 0360-3199, E-ISSN 1879-3487, Vol. 38, no 36, p. 16524-16531Article in journal (Refereed)
    Abstract [en]

    Ceria-based electrolyte materials have great potential in low and intermediate temperature solid oxide fuel cell applications. In the present study, three types of ceria-based nanocomposite electrolytes (LNK-SDC, LN-SDC and NK-SDC) were synthesized. One-step co-precipitation method was adopted and different techniques were applied to characterize the obtained ceria-based nano-composite electrolyte materials. TGA, XRD and SEM were used to analyze the thermal effect, crystal structure and morphology of the materials. Cubic fluorite structures have been observed in all composite electrolytes. Furthermore, the crystallite sizes of the LN-SDC, NK-SDC, LNK-SDC were calculated by Scherrer formula and found to be in the range 20 nm, 21 nm and 19 nm, respectively. These values emphasize a good agreement with the SEM results. The ionic conductivities were measured using EIS (Electrochemical Impedance Spectroscopy) with two-probe method and the activation energies were also calculated using Arrhenius plot. The maximum power density was achieved 484 mW/cm(2) of LNK-SDC electrolyte at 570 degrees C using the LiCuZnNi oxide electrodes.

  • 3005.
    Ajne, Joel
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Real Estate and Construction Management.
    Peterhoff, Marcus
    KTH, School of Architecture and the Built Environment (ABE), Real Estate and Construction Management.
    Digitalisering inom den Svenska Fastighetsmarknaden2018Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    PropTech has become a worldwide phenomenon in the real estate market. The attribute of digitization benefit the entire range of owners, investors and tenants. Cost-efficiency, time optimization and the renewal of stereotypes are some of the reasons for this. In Sweden, interest has risen sharply over the past three years, but the real estate industry is slow moving and it is only until now that real estate companies begin to realize the value of applying the new technology. The purpose of the report is to get a market view of how the Swedish real estate industry defines PropTech and digitization, as well as investigate how companies look at the future of the subject. The problem is answered using expert interviews that also form the basis for the analysis. The perception of the significance of digitization varies depending on ownership and yield, while it is clear that the mission of a property owner will change in the future.

  • 3006. Aka, Menny
    et al.
    Breuillard, Emmanuel
    Rosenzweig, Lior
    KTH, School of Engineering Sciences (SCI), Mathematics (Dept.).
    de Saxce, Nicolas
    Diophantine properties of nilpotent Lie groups2015In: Compositio Mathematica, ISSN 0010-437X, E-ISSN 1570-5846, Vol. 151, no 6, p. 1157-1188Article in journal (Refereed)
    Abstract [en]

    A finitely generated subgroup F of a real Lie group G is said to be Diophantine if there is beta > 0 such that non-trivial elements in the word ball B-Gamma(n) centered at 1 is an element of F never approach the identity of G closer than broken vertical bar Br(n)broken vertical bar(-beta). A Lie group G is said to be Diophantine if for every k >= 1 a random k-tuple in G generates a Diophantine subgroup. Semi-simple Lie groups are conjectured to be Diophantine but very little is proven in this direction. We give a characterization of Diophantine nilpotent Lie groups in terms of the ideal of laws of their Lie algebra. In particular we show that nilpotent Lie groups of class at most 5, or derived length at most 2, as well as rational nilpotent Lie groups are Diophantine. We also find that there are non-Diophantine nilpotent and solvable (non-nilpotent) Lie groups.

  • 3007. Aka, Menny
    et al.
    Breuillard, Emmanuel
    Rosenzweig, Lior
    KTH, School of Engineering Sciences (SCI), Mathematics (Dept.), Mathematics (Div.).
    de Saxce, Nicolas
    On metric Diophantine approximation in matrices and Lie groups2015In: Comptes rendus. Mathematique, ISSN 1631-073X, E-ISSN 1778-3569, Vol. 353, no 3, p. 185-189Article in journal (Refereed)
    Abstract [en]

    We study the Diophantine exponent of analytic submanifolds of m x n real matrices, answering questions of Beresnevich, Kleinbock, and Margulis. We identify a family of algebraic obstructions to the extremality of such a submanifold, and give a formula for the exponent when the submanifold is algebraic and defined over Q. We then apply these results to the determination of the Diophantine exponent of rational nilpotent Lie groups.

  • 3008. Akabori, M.
    et al.
    Hidaka, S.
    Iwase, H.
    Yamada, S.
    Ekenberg, Ulf
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics.
    Realization of In0.75Ga0.25As two-dimensional electron gas bilayer system for spintronics devices based on Rashba spin-orbit interaction2012In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 112, no 11, p. 113711-Article in journal (Refereed)
    Abstract [en]

    Narrow gap InGaAs two-dimensional electron gas (2DEG) bilayer samples are fabricated and confirmed to have good electronic qualities as well as strong Rashba-type spin-orbit interactions (SOIs). The 2DEG systems are realized by molecular beam epitaxy in the form of wide quantum wells (QWs) with thicknesses tQW∼40-120nm modulation doped in both the upper and lower InAlAs barriers. From the Hall measurements, the overall mobility values of μe ∼15 m2/V s are found for the total sheet electron density of ns ∼8 × 1011/cm2, although the ns is distributed asymmetrically as about 1:3 in the upper and lower 2DEGs, respectively. Careful low temperature magneto-resistance analysis gives large SO coupling constants of α ∼20 × 10 -12eV m as well as expected electron effective masses of m*/m0 ∼0.033-0.042 for each bilayer 2DEG spin sub-band. Moreover, the enhancement of α with decrease of tQW is found. The corresponding self-consistent calculation, which suggests the interaction between the bilayer 2DEGs, is carried out and the origin of α enhancement is discussed.

  • 3009.
    Akan, Pelin
    et al.
    KTH, School of Biotechnology (BIO), Gene Technology. KTH, Centres, Science for Life Laboratory, SciLifeLab.
    Alexeyenko, Andrey
    KTH, School of Biotechnology (BIO), Gene Technology. KTH, Centres, Science for Life Laboratory, SciLifeLab.
    Costea, Paul Igor
    KTH, School of Biotechnology (BIO), Gene Technology. KTH, Centres, Science for Life Laboratory, SciLifeLab.
    Hedberg, Lilia
    KTH, School of Biotechnology (BIO), Gene Technology. KTH, Centres, Science for Life Laboratory, SciLifeLab.
    Werne Solnestam, Beata
    KTH, School of Biotechnology (BIO), Gene Technology. KTH, Centres, Science for Life Laboratory, SciLifeLab.
    Lundin, Sverker
    KTH, School of Biotechnology (BIO), Gene Technology. KTH, Centres, Science for Life Laboratory, SciLifeLab.
    Hallman, Jimmie
    Lundberg, Emma
    KTH, School of Biotechnology (BIO), Gene Technology. KTH, Centres, Science for Life Laboratory, SciLifeLab.
    Uhlén, Mathias
    KTH, School of Biotechnology (BIO), Proteomics (closed 20130101). KTH, Centres, Science for Life Laboratory, SciLifeLab.
    Lundeberg, Joakim
    KTH, School of Biotechnology (BIO), Gene Technology. KTH, Centres, Science for Life Laboratory, SciLifeLab.
    Comprehensive analysis of the genome transcriptome and proteome landscapes of three tumor cell lines2012In: Genome Medicine, ISSN 1756-994X, E-ISSN 1756-994X, Vol. 4, p. 86-Article in journal (Refereed)
    Abstract [en]

    We here present a comparative genome, transcriptome and functional network analysis of three human cancer cell lines (A431, U251MG and U2OS), and investigate their relation to protein expression. Gene copy numbers significantly influenced corresponding transcript levels; their effect on protein levels was less pronounced. We focused on genes with altered mRNA and/or protein levels to identify those active in tumor maintenance. We provide comprehensive information for the three genomes and demonstrate the advantage of integrative analysis for identifying tumor-related genes amidst numerous background mutations by relating genomic variation to expression/protein abundance data and use gene networks to reveal implicated pathways.

  • 3010.
    Akan, Pelin
    et al.
    KTH, Centres, Science for Life Laboratory, SciLifeLab. KTH, School of Biotechnology (BIO).
    Stranneheim, Henrik
    KTH, Centres, Science for Life Laboratory, SciLifeLab. KTH, School of Biotechnology (BIO).
    Lexow, Preben
    LingVitae, Oslo.
    Lundeberg, Joakim
    KTH, Centres, Science for Life Laboratory, SciLifeLab. KTH, School of Biotechnology (BIO).
    Design and assessment of binary DNA for nanopore sequencing2010In: Genome biology, ISSN 1474-760X, Vol. 11, p. P4-Article in journal (Other academic)
  • 3011.
    Akan, Rabia
    KTH, School of Chemical Science and Engineering (CHE).
    Oorganiska-organiska nanopartikelbaserade supramolekylära strukturer för biomedicinska applikationer2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The possibility to create a multifunctional nanoparticle system via supramolecular chemistry approach with ability to simultaneously target, deliver and diagnose was investigated. Superparamagnetic iron oxide nanoparticles were synthesized by co-precipitation method and surface modified with the cyclic oligosaccharide carboxymethyl-β-cyclodextrin by three different routes. The different routes involved one, two or three reaction steps in order to reach to the final oligosaccharide functionalized nanoparticles. Esterification was performed using the intrinsic hydroxyl functionality of the nanoparticle surfaces or amine functionality was introduced prior to amidization. Further, a polymeric coating was created by incorporation of folic acid functionalized Pluronic® L-35 into carboxymethyl-β-cyclodextrin. The resulting nanoparticle based supramolecular systems were characterized by TEM, TGA, FT-IR, DLS and zeta potential techniques.

     

    The colloidal stabilities of the supramolecular nanoparticle systems were investigated in phosphate buffered saline with pH 7.4 representing body conditions. It was found that a three-step functionalization of iron oxide nanoparticles with citric acid, hexamethylenediamine and finally carboxymethyl-β-cyclodextrin resulted in the most stable ferrofluids. The average size of the resulting carboxymethyl-β-cyclodextrin functionalized nanoparticles was 25 nm prior to, and 50 nm after inclusion of folic acid functionalized Pluronic. The amount of grafted carboxymethyl-β-cyclodextrin on the nanoparticles surfaces was 25 weight %. Thus, the resulting stable ferrofluid creates an efficient platform with potential of multiple uses in biomedicine. This nanoparticle based supramolecular system combines the properties of magnetic targeting and MRI contrast enhancement due to the superparamagnetic iron oxide nanoparticle core, drug delivery of hydrophobic drugs due to the polymer capsule and selective targeting towards tumour cells due to the folic acid.

  • 3012.
    Akan, Rabia
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Parfeniukas, Karolis
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Vogt, Carmen
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Toprak, M. S.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Vogt, Ulrich
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Reaction control of metal-assisted chemical etching for silicon-based zone plate nanostructures2018In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 8, no 23, p. 12628-12634Article in journal (Refereed)
    Abstract [en]

    Metal-assisted chemical etching (MACE) reaction parameters were investigated for the fabrication of specially designed silicon-based X-ray zone plate nanostructures using a gold catalyst pattern and etching solutions composed of HF and H2O2. Etching depth, zone verticality and zone roughness were studied as a function of etching solution composition, temperature and processing time. Homogeneous, vertical etching with increasing depth is observed at increasing H2O2 concentrations and elevated processing temperatures, implying a balance in the hole injection and silica dissolution kinetics at the gold-silicon interface. The etching depth decreases and zone roughness increases at the highest investigated H2O2 concentration and temperature. Possible reasons for these observations are discussed based on reaction chemistry and zone plate design. Optimum MACE conditions are found at HFH2O2 concentrations of 4.7 M:0.68 M and room temperature with an etching rate of ≈0.7 μm min-1, which is about an order of magnitude higher than previous reports. Moreover, our results show that a grid catalyst design is important for successful fabrication of vertical high aspect ratio silicon nanostructures. 

  • 3013.
    Akan, Rabia
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Parfeniukas, Karolis
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics. KTH Royal Institute of Technology.
    Vogt, Carmen
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Toprak, Muhammet S.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Vogt, Ulrich
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Reaction control of metal-assisted chemical etching for silicon-based zone plate nanostructuresManuscript (preprint) (Other academic)
    Abstract [en]

    Metal-assisted chemical etching (MACE) reaction parameters were investigated for the fabrication of specially designed silicon-based x-ray zone plate nanostructures using a gold catalyst pattern and etching solutions composed of HF and H2O2. Etching depth, zone verticality and zone roughness were studied as a function of etching solution composition, temperature and processing time. Homogeneous, vertical etching with increasing depth is observed at increasing H2O2 concentrations and elevated processing temperatures, implying a balance in the hole injection and silica dissolution kinetics at the gold-silicon interface. The etching depth decreases and zone roughness increases at the highest investigated H2O2 concentration and temperature. Possible reasons for these observations are discussed based on reaction chemistry and zone plate design. Optimum MACE conditions are found at HF:H2O2 concentrations of 4.7 M:0.68 M and room temperature with an etching rate of 0.7 micrometers per minute, which is about an order of magnitude higher than previous reports. Moreover, our results show that a grid catalyst design is important for successful fabrication of vertical high aspect ratio silicon nanostructures.

  • 3014.
    Akander, Amanda
    KTH, School of Biotechnology (BIO).
    Development and Evaluation of a Lateral Flow Immunoassay for on-site Diagnosisof Contagious Bovine Pleuropneumonia2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The purpose of this study was to develop and evaluate a lateral flow immunoassay, as a point-of-care prototype for diagnosis of contagious bovine pleuropneumonia (CBPP). The assay was based on a panel of recombinant proteins spotted on a nitrocellulose membrane. The study included optimization of assay components, such as running buffer and protein microarray layout. The purpose was to obtain a clear discriminatory capacity between CBPP positive and CBPP negative sera, by developing and evaluating a lateral flow immunoassay that could be used on-site.

    The discriminatory capacity between CBPP positive sera and CBPP negative sera in the lateral flow assay was statistically significant with p-values ≤0.05 for recombinant proteins to be printed in microarray spots both individually as well as proteins printed as mixtures. The sensitivity of the assay was 64% and the specificity 100%, which was comparable to current diagnostic methods for CBPP. From these rsults, four combinations of recombinant proteins were selected to print as a microarray, which was based on p-valuesas well as sera coverage. As the purpose of this study was to develop a prototype for on-site usage, a fieldtrip to Nairobi, Kenya, facilitated by the Swedish International Development Cooperation Agency, SIDA, was made to test the prototpyes as well as obtain deeper knowledge of user area. However, the lateral flow immunoassay did not deliver reproducible and stable results during the field trip to Kenya.

  • 3015.
    Akander, Amanda
    KTH, School of Biotechnology (BIO).
    Massive parallell DNA-sequencing - future methods to obtain a human genome in 15 minutes2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
  • 3016.
    Akander, Jan
    KTH, Superseded Departments, Building Sciences and Engineering.
    The ORC method2000Doctoral thesis, comprehensive summary (Other scientific)
    Abstract [en]

    The ORC Method (Optimised RC-networks) provides a means ofmodelling one- or multidimensional heat transfer in buildingcomponents, in this context within building simulationenvironments. The methodology is shown, primarily applied toheat transfer in multilayer building components. For multilayerbuilding components, the analytical thermal performance isknown, given layer thickness and material properties. The aimof the ORC Method is to optimise the values of the thermalresistances and heat capacities of an RC-model such as to givemodel performance a good agreement with the analyticalperformance, for a wide range of frequencies. The optimisationprocedure is made in the frequency domain, where the over-alldeviation between model and analytical frequency response, interms of admittance and dynamic transmittance, is minimised. Itis shown that ORC's are effective in terms of accuracy andcomputational time in comparison to finite difference modelswhen used in building simulations, in this case with IDA/ICE.An ORC configuration of five mass nodes has been found to modelbuilding components in Nordic countries well, within theapplication of thermal comfort and energy requirementsimulations.

    Simple RC-networks, such as the surface heat capacity andthe simple R-C-configuration are not appropriate for detailedbuilding simulation. However, these can be used as basis fordefining the effective heat capacity of a building component.An approximate method is suggested on how to determine theeffective heat capacity without the use of complex numbers.This entity can be calculated on basis of layer thickness andmaterial properties with the help of two time constants. Theapproximate method can give inaccuracies corresponding to20%.

    In-situ measurements have been carried out in anexperimental building with the purpose of establishing theeffective heat capacity of external building components thatare subjected to normal thermal conditions. The auxiliary wallmethod was practised and the building was subjected toexcitation with radiators. In a comparison, there werediscrepancies between analytical and measured effective heatcapacities. It was found that high-frequency discrepancies wereto a large extent caused by the heat flux sensors.Low-frequency discrepancies are explained by the fact that theexterior climate contained other frequencies than those assumedin the interior climate.

    Key words: Building component, building simulation, heattransfer, thermal performance, frequency response, RC-network,finite difference model.

  • 3017.
    Akander, Jan
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering.
    Alvarez, S
    Jóhannesson, Gundi
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering.
    Energy normalization techniques2004In: Energy Performance of Residential Buildings: A Practical Guide for Energy Rating and Efficiency, James & James/Earthscan , 2004, p. 57-70Chapter in book (Other academic)
  • 3018.
    Akander, Jan
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering.
    Jóhnnesson, Gudini
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering.
    Experimental methods for the energy characterization of buildings2004In: Energy Performance of Residential Buildings: A Practical Guide for Energy Rating and Efficiency, James & James/Earthscan , 2004, p. 26-56Chapter in book (Other academic)
  • 3019.
    Akay, Altug
    KTH, School of Technology and Health (STH), Health Systems Engineering, Systems Safety and Management.
    A Novel Method to Intelligently Mine Social Media to Assess Consumer Sentiment of Pharmaceutical Drugs2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis focuses on the development of novel data mining techniques that convert user interactions in social media networks into readable data that would benefit users, companies, and governments. The readable data can either warn of dangerous side effects of pharmaceutical drugs or improve intervention strategies. A weighted model enabled us to represent user activity in the network, that allowed us to reflect user sentiment of a pharmaceutical drug and/or service. The result is an accurate representation of user sentiment. This approach, when modified for specific diseases, drugs, and services, can enable rapid user feedback that can be converted into rapid responses from consumers to industry and government to withdraw possibly dangerous drugs and services from the market or improve said drugs and services.

    Our approach monitors social media networks in real-time, enabling government and industry to rapidly respond to consumer sentiment of pharmaceutical drugs and services.

  • 3020.
    Akay, Altug
    et al.
    KTH, School of Technology and Health (STH), Health Systems Engineering, Systems Safety and Management.
    Dragomir, A.
    Department of Biomedical Engineering, University of Houston, Houston, TX, US.
    Erlandsson, Björn-Erik
    KTH, School of Technology and Health (STH), Health Systems Engineering, Systems Safety and Management.
    A novel data-mining approach leveraging social media to monitor and respond to outcomes of diabetes drugs and treatment2013In: 2013 IEEE Point-of-Care Healthcare Technologies (PHT), New York: IEEE , 2013, p. 264-266Conference paper (Refereed)
    Abstract [en]

    A novel data-mining method was developed to gauge the experiences of medical devices and drugs by patients with diabetes mellitus. Self-organizing maps were used to analyze forum posts numerically to better understand user opinion of medical devices and drugs. The end-result is a word list compilation that correlates certain positive and negative word cluster groups with medical drugs and devices. The implication of this novel data-mining method could open new avenues of research into rapid data collection, feedback, and analysis that would enable improved outcomes and solutions for public health.

  • 3021.
    Akay, Altug
    et al.
    KTH, School of Technology and Health (STH), Health Systems Engineering, Systems Safety and Management.
    Dragomir, A
    Erlandsson, Björn-Erik
    KTH, School of Technology and Health (STH), Health Systems Engineering, Systems Safety and Management.
    A Novel Data-Mining Approach Leveraging Social Media to Monitor Consumer Opinion of Sitagliptin2015In: IEEE journal of biomedical and health informatics, ISSN 2168-2194, E-ISSN 2168-2208, Vol. 19, no 1, p. 389-396Article in journal (Refereed)
    Abstract [en]

    A novel data mining method was developed to gauge the experience of the drug Sitagliptin (trade name Januvia) by patients with diabetes mellitus type 2. To this goal, we devised a two-step analysis framework. Initial exploratory analysis using self-organizing maps was performed to determine structures based on user opinions among the forum posts. The results were a compilation of user's clusters and their correlated (positive or negative) opinion of the drug. Subsequent modeling using network analysis methods was used to determine influential users among the forum members. These findings can open new avenues of research into rapid data collection, feedback, and analysis that can enable improved outcomes and solutions for public health and important feedback for the manufacturer.

  • 3022.
    Akay, Altug
    et al.
    KTH, School of Technology and Health (STH), Health Systems Engineering, Systems Safety and Management.
    Dragomir, A.
    Erlandsson, Björn-Erik
    KTH, School of Technology and Health (STH), Health Systems Engineering, Systems Safety and Management.
    A novel data-mining platform leveraging social media to monitor outcomes of Januvia2013In: Engineering in Medicine and Biology Society (EMBC), 2013 35th Annual International Conference of the IEEE, IEEE conference proceedings, 2013, p. 7484-7487Conference paper (Refereed)
    Abstract [en]

    A novel data-mining method was developed to gauge the experiences of the diabetes mellitus drug Januvia. Self-organizing maps were used to analyze forum posts numerically to infer user opinion of drug Januvia. Graph theory was used to discover influential users. The result is a word list compilation correlating positive and negative word cluster groups and a web of influential users on Januvia. The implications could open new research avenues into rapid data collection, feedback, and analysis that would enable improved solutions for public health.

  • 3023.
    Akay, Altug
    et al.
    KTH, School of Technology and Health (STH), Health Systems Engineering, Systems Safety and Management.
    Dragomir, A
    Erlandsson, Björn-Erik
    KTH, School of Technology and Health (STH), Health Systems Engineering, Systems Safety and Management.
    Network-Based Modeling and Intelligent Data Mining of Social Media for Improving Care2015In: IEEE journal of biomedical and health informatics, ISSN 2168-2194, E-ISSN 2168-2208, Vol. 19, no 1, p. 210-218Article in journal (Refereed)
    Abstract [en]

    Intelligently extracting knowledge from social media has recently attracted great interest from the Biomedical and Health Informatics community to simultaneously improve healthcare outcomes and reduce costs using consumer-generated opinion. We propose a two-step analysis framework that focuses on positive and negative sentiment, as well as the side effects of treatment, in users' forum posts, and identifies user communities (modules) and influential users for the purpose of ascertaining user opinion of cancer treatment. We used a self-organizing map to analyze word frequency data derived from users' forum posts. We then introduced a novel network-based approach for modeling users' forum interactions and employed a network partitioning method based on optimizing a stability quality measure. This allowed us to determine consumer opinion and identify influential users within the retrieved modules using information derived from both word-frequency data and network-based properties. Our approach can expand research into intelligently mining social media data for consumer opinion of various treatments to provide rapid, up-to-date information for the pharmaceutical industry, hospitals, and medical staff, on the effectiveness (or ineffectiveness) of future treatments.

  • 3024.
    Akay, Altug
    et al.
    KTH, School of Technology and Health (STH), Health Systems Engineering, Systems Safety and Management.
    Dragomir, Andrei
    Erlandsson, Björn-Erik
    KTH, School of Technology and Health (STH), Health Systems Engineering, Systems Safety and Management.
    A Novel-Data Mining Platform to Monitor the Outcomes of Erlontinib (Tarceva) using Social Media2014In: XIII Mediterranean Conference on Medical and Biological Engineering and Computing 2013, Springer, 2014, p. 1394-1397Conference paper (Refereed)
    Abstract [en]

    A novel data-mining method was developed to gauge the experiences of the oncology drug Tarceva. Self-organizing maps were used to analyze forum posts numerically to infer user opinion of drug Tarceva. The result is a word list compilation correlating positive and negative word cluster groups and a web of influential users on Tarceva. The implica-tions could open new research avenues into rapid data collec-tion, feedback, and analysis that would enable improved solu-tions for public health.

  • 3025.
    Akay, Altug
    et al.
    KTH, School of Technology and Health (STH), Health Systems Engineering, Systems Safety and Management.
    Dragomir, Andrei
    Erlandsson, Björn-Erik
    KTH, School of Technology and Health (STH), Health Systems Engineering, Systems Safety and Management.
    Assessing Antidepressants Using Intelligent Data Monitoring and Mining of Online Fora2016In: IEEE journal of biomedical and health informatics, ISSN 2168-2194, E-ISSN 2168-2208, Vol. 20, no 4, p. 977-986Article in journal (Refereed)
    Abstract [en]

    Depression is a global health concern. Social networks allow the affected population to share their experiences. These experiences, when mined, extracted, and analyzed, can be converted into either warnings to recall drugs (dangerous side effects), or service improvement (interventions, treatment options) based on observations derived from user behavior in depression-related social networks. Our aim was to develop a weighted network model to represent user activity on social health networks. This enabled us to accurately represent user interactions by relying on the data's semantic content. Our three-step method uses the weighted network model to represent user's activity, and network clustering and module analysis to characterize user interactions and extract further knowledge from user's posts. The network's topological properties reflect user activity such as posts' general topic as well as timing, while weighted edges reflect the posts semantic content and similarities among posts. The result, a synthesis from word data frequency, statistical analysis of module content, and the modeled health network's properties, has allowed us to gain insight into consumer sentiment of antidepressants. This approach will allow all parties to participate in improving future health solutions of patients suffering from depression.

  • 3026.
    Akay, Altug
    et al.
    KTH, School of Technology and Health (STH), Health Systems Engineering, Systems Safety and Management.
    Dragomir, Andrei
    University of Houston, Biomedical Engineering.
    Erlandsson, Björn-Erik
    KTH, School of Technology and Health (STH), Health Systems Engineering.
    Mining Social Media Big Data for Health2015In: IEEE PulseArticle, review/survey (Refereed)
    Abstract [en]

    Advances in information technology (IT) and big data are affecting nearly every facet of the public and private sectors. Social media platforms are one example of such advances: its nature allows users to connect, collaborate, and debate on any topic with comparative ease. The result is a hefty volume of user-generated content that, if properly mined and analyzed, could help the public and private health care sectors improve the quality of their products and services while reducing costs. The users of these platforms are the key to these improvements, as their valuable feedback will help improve health solutions.

  • 3027. Akbar, F.
    et al.
    Kolahdouz, M.
    Larimian, Sh.
    Radfar, B.
    Radamson, Henry
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Graphene synthesis, characterization and its applications in nanophotonics, nanoelectronics, and nanosensing2015In: Journal of materials science. Materials in electronics, ISSN 0957-4522, E-ISSN 1573-482X, Vol. 26, no 7, p. 4347-4379Article in journal (Refereed)
    Abstract [en]

    In the last decade, as semiconductor industry was approaching the end of the exponential Moore's roadmap for device downscaling, the necessity of finding new candidate materials has forced many research groups to explore many different types of non-conventional materials. Among them, graphene, CNTs and organic conductors are the most successful alternatives. Finding a material with metallic properties combined with field effect characteristics on nanoscale level has been always a dream to continue the ever-shrinking road of the nanoelectronics. Due to its fantastic features such as high mobility, optical transparency, room temperature quantum Hall effect, mechanical stiffness, etc. the atomically thin carbon layer, graphene, has attracted the industry's attention not only in the micro-, nano-, and opto-electronics but also in biotechnology. This paper reviews the basics and previous works on graphene technology and its developments. Compatibility of this material with Si processing technology is its crucial characteristic for mass production. This study also reviews the physical and electrical properties of graphene as a building block for other carbon allotropes. Different growth methods and a wide range of graphene's applications will be discussed and compared. A brief comparison on the performance result of different types of devices has also been presented. Until now, the main focus of research has been on the background physics and its application in electronic devices. But, according to the recent works on its applications in photonics and optoelectronics, where it benefits from the combination of its unique optical and electronic properties, even without a bandgap, this material enables ultrawide-band tunability. Here in this article we review different applications and graphene's advantages and drawbacks will be mentioned to conclude at the end.

  • 3028.
    AKBARI KHALIL ABAD, HANNANE
    et al.
    KTH, School of Chemical Science and Engineering (CHE).
    ARONSSON, JENS
    KTH, School of Chemical Science and Engineering (CHE).
    PERSSON, ALEXANDER
    KTH, School of Chemical Science and Engineering (CHE).
    REINECK POPA, ERIK
    KTH, School of Chemical Science and Engineering (CHE).
    Heterogen katalys för produktion av biodiesel från rester av matolja2015Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Energikonsumtionen inom transportsektor består till störst del av konsumtion av fossila bränslen. Transportsektorn själv står för ca 30 % av världens totala energikonsumtion. Att växla till ett grönt drivmedel skulle bidra till en mer ekologiskt hållbar verksamhet.

    Biodiesel kan vara svaret på transportsektorns problem och kan dessutom framställas av vad man idag anser är avfall. Restmatolja kan med hjälp av katalysatorer transesterifieras till biodiesel som efter inblandning av konventionell diesel kan köras i dagens dieselmotorer.

    För att spara resurser är en process med heterogen katalysator bättre än en homogen process. I rapporten undersöks om MgO, CaO och Li2O kan användas som katalysator för att framställa biodieseln från restmatoljan. Studien undersöker också om SnO eller SnO2 kan tillsättas till katalysatorn för att öka utbytet.

    Försök genomfördes i labbmiljö med restolja från en lokal restaurang. Olika parametrar testades för att optimera utbytet. Parametrarna som ändrades var temperatur, mängd katalysator och molförhållandet mellan alkohol och olja. Varje parameter varierades mellan två värden.

    Resultaten visade att CaO var den enda av de undersökta katalysatorerna som fungerade och gav ett tillräckligt bra utbyte. SnO som användes tillsammans med CaO visade en liten effekt av att öka utbytet, men antalet försök var för få för att kunna dra några säkra slutsatser.

    Resultaten från undersökningen av optimala parametrar visar att utbytet minskar med ökande temperatur. Större andel alkohol jämfört med olja ger ett högre utbyte. Med ökande mängd katalysator finns ett optimalt värde och när det överskrids minskar utbytet igen.

    Vidare studier krävs för att optimera de heterogena katalysatorerna i biodieselframställningen.

  • 3029. Akbari, N.
    et al.
    Modarressi, M.
    Daneshtalab, Masoud
    KTH.
    Loni, Efisio
    KTH.
    A Customized Processing-in-Memory Architecture for Biological Sequence Alignment2018In: Proceedings of the International Conference on Application-Specific Systems, Architectures and Processors, Institute of Electrical and Electronics Engineers Inc. , 2018, Vol. 2018, article id 8445124Conference paper (Refereed)
    Abstract [en]

    Sequence alignment is the most widely used operation in bioinformatics. With the exponential growth of the biological sequence databases, searching a database to find the optimal alignment for a query sequence (that can be at the order of hundreds of millions of characters long) would require excessive processing power and memory bandwidth. Sequence alignment algorithms can potentially benefit from the processing power of massive parallel processors due their simple arithmetic operations, coupled with the inherent fine-grained and coarse-grained parallelism that they exhibit. However, the limited memory bandwidth in conventional computing systems prevents exploiting the maximum achievable speedup. In this paper, we propose a processing-in-memory architecture as a viable solution for the excessive memory bandwidth demand of bioinformatics applications. The design is composed of a set of simple and lightweight processing elements, customized to the sequence alignment algorithm, integrated at the logic layer of an emerging 3D DRAM architecture. Experimental results show that the proposed architecture results in up to 2.4x speedup and 41% reduction in power consumption, compared to a processor-side parallel implementation.

  • 3030.
    Akbaripour Sheijnai, Solmaz
    KTH, School of Engineering Sciences (SCI), Mechanics.
    Numerical studies on receptivity and control of a three-dimensional boundary layer2012Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Receptivity in three-dimensional boundary layer ow to localized roughness elements over a at plate is studied by means of direct numerical simulations (DNS). The surface roughness is modeled by applying nonhomogeneous boundary conditions along the wall as well as considering as a surface deformation by inserting the bump shape into the numerical mesh. Under the assumption of the small amplitudes of the roughness, although dierent disturbances amplitudes are observed in the vicinity of the bump for the meshed and modeled case, the boundary layer response downstream of the roughness is independent if the way of the bump implementation. Dierent roughness heights are considered in order to compare the boundary layer response of two approaches. Also, the boundary layer is excited by random distributed surface roughness and the receptivity results are studied. Moreover, a simple model for natural roughness excites steady multi wavenumber crossow instabilities. A localised surface roughness i.e. control roughness is applied to stabilise the latter. The control mode which is subcritical with respect to transition aects the most steady unstable mode. Suppression of the most dangerous mode is observed through nonlinear interactions with the control mode.

  • 3031.
    Akbarnejad, Shahin
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Experimental and Mathematical Study of Incompressible Fluid Flow through Ceramic Foam Filters2016Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Ceramic Foam Filters (CFFs) are widely used to filter solid particles and inclusions from molten metal in metal production, particularly in the aluminum industry. In general, the molten metal is poured on the top of a ceramic foam filter until it reaches a certain height, also known as metal head or gravity head. This is done to build the required pressure to prime the filter media and to initiate filtration. To predict the required metal head, it is necessary to obtain the Darcy and non-Darcy permeability coefficients of the filter. The coefficients vary upon filter type. Here, it is common to classify CFFs based on grades or pore per inches (PPI). These CFFs range from10 to100 PPI and their properties vary in everything from cell and window size to strut size. The 80-100 PPI CFFs are generally not practical for use by industry, since the priming of the filters by a gravitational force requires an excessive metal head. However, recently a new method has been developed to prime such filters by using electromagnetic Lorentz forces. This allows the filters to be primed at a low metal head.

    To continue the research work, it was deemed necessary to measure the pressure gradients of single and stack of commercial alumina ceramic foam filters and to obtain the permeability characteristics. Therefore, efforts have been made to validate the previously obtained results, to improve the permeametry experimental setup, and to obtain Darcy and non-Darcy permeability coefficients of single 30, 50, and 80 PPI filters and stacks of filters. Furthermore, the experimentally obtained pressure gradients were analyzed and compered to the mathematically and analytically estimated pressure gradients.

    The studies showed that, in permeametry experiments, the sample sealing procedure plays an important role for an accurate estimation of the permeability constants. An inadequate sealing or an un-sealed sample results in an underestimation of the pressure drop, which causes a considerable error in the obtained Darcy and non-Darcy permeability coefficients. Meanwhile, the results from the single filter experiments showed that the permeability values of the similar PPI filters are not identical. However, the stacks of three identical filters gave substantially the same measured pressure drop values and roughly the same Darcy and non-Darcy coefficients as for the single filters.

    The permeability coefficients of the filters are believed to be best defined and calculated by using the Forchheimer equation. The well-known and widely used Ergun and Dietrich equations cannot correctly predict the pressure drop unless a correction factor is introduced. The accuracy of the mathematically estimated pressure drop, using COMSOL Multiphysics® 5.1, found to be dependent on the drag term used in the Brinkman-Forchheimer equation.  Unacceptable error, as high as 84 to 89 percent for the 30, 50 and 80 PPI single filters, compared to the experimentally obtained pressure gradient values were observed when the literature defined Brinkman-Forchheimer drag term was used. However, when the same second order drag term (containing the non-Darcy coefficient) as defined in the Forchheimer equation was used, the predicted pressure gradient profiles satisfactorily agreed with the experiment data with as little as 0.3 to 5.5 percent deviations for the 30, 50 and 80 PPI single filters.

  • 3032.
    Akbarnejad, Shahin
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Investigation on static strength of welded joints2012Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Although high strength steels represent yield strength up to 1300 MPa, welded structures reveal lowerstrength values. The strongest commercially available electrode provides the yield strength of about900 MPa. Therefore, in welded steels with strength above this type of filler metal, achieving anacceptable global strength is a crucial issue.

    In this master thesis, affects of different welding procedures on static strength of welded jointsof Weldox 960 and Weldox 1100 steels, were studied. These steels are produced by SSAB inOxelösund. Meanwhile, finite element method analyses were applied in order to investigatethe static strength behavior of such weldments under uniaxial tension.

    The welding parameters which were selected as variables are:

    •  Heat input
    • Weld joint geometry
    • Filler metal

    When weld metal is undermatching in strength levels than the base material, by applyingtension the soft weld metal begins to deform before parent metal. At that point thedeformation of resulted soft zone, including the weld metal and the heat affected zone, ishindered by high strength parent metal. Thus, uniaxial stress caused by uniaxial load isconverted to multiaxial stress. This conversion in tension results in increase in the staticstrength of weldment. The increase in strength is emphasized by increase in the width of thewelded joint while the thickness of the plate is kept as constant.

    After experiments and performing FEM studies, it was revealed that the static strength ofWeldox 960 welded joints approaches towards the tensile strength of parent metal by increasein the width of the weldment. In Weldox 1100 joints; a slight increase in tensile properties ofthe weldments, when the width of the sample increases, was observed.

  • 3033.
    Akbarnejad, Shahin
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Jonsson, Lage
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Kennedy, M. W.
    Aune, R. E.
    Jönsson, Pär
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Analysis on Experimental Investigation and Mathematical Modelling of Incompressible Flow through Ceramic Foam FiltersManuscript (preprint) (Other academic)
  • 3034.
    Akbarnejad, Shahin
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Jonsson, Lage Tord Ingemar
    Kennedy, Mark William
    Aune, Ragnhild Elizabeth
    Jönsson, Pär
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Analysis on Experimental Investigation and Mathematical Modeling of Incompressible Flow Through Ceramic Foam Filters2016In: Metallurgical and materials transactions. B, process metallurgy and materials processing science, ISSN 1073-5615, E-ISSN 1543-1916, Vol. 47, no 4, p. 2229-2243Article in journal (Refereed)
    Abstract [en]

    This paper presents experimental results of pressure drop measurements on 30, 50, and 80 pores per inch (PPI) commercial alumina ceramic foam filters (CFF) and compares the obtained pressure drop profiles to numerically modeled values. In addition, it is aimed at investigating the adequacy of the mathematical correlations used in the analytical and the computational fluid dynamics (CFD) simulations. It is shown that the widely used correlations for predicting pressure drop in porous media continuously under-predict the experimentally obtained pressure drop profiles. For analytical predictions, the negative deviations from the experimentally obtained pressure drop using the unmodified Ergun and Dietrich equations could be as high as 95 and 74 pct, respectively. For the CFD predictions, the deviation to experimental results is in the range of 84.3 to 88.5 pct depending on filter PPI. Better results can be achieved by applying the Forchheimer second-order drag term instead of the Brinkman-Forchheimer drag term. Thus, the final deviation of the CFD model estimates lie in the range of 0.3 to 5.5 pct compared to the measured values.

  • 3035.
    Akbarnejad, Shahin
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Kennedy, M. W.
    Fritzsch, R.
    Aune, R. E.
    An investigation on permeability of ceramic foam filters (CFF)2015In: TMS Light Metals, 2015, p. 949-954Conference paper (Refereed)
    Abstract [en]

    CFFs are used to filter liquid metal in the aluminum industry. CFFs are classified in grades or pores per inch (PPI), ranging from 10-100 PPI. Their properties vary in everything from pore and strut size to window size. CFFs of 80-100 PPI are generally not practical for use by industry, as priming of the filters by gravitational forces requires an excessive metal head. Recently, co-authors have invented a method to prime such filters using electromagnetic Lorentz forces, thus allowing filters to be primed with a low metal head. In the continuation of this research work, an improved experimental setup was developed in the present study to validate previous results and to measure the permeability of different filters, as well as a stack of filters. The study of permeability facilitates estimation of the required pressure drop to prime the filters and the head required to generate a given casting rate.

  • 3036.
    Akbarnejad, Shahin
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Saffari Pour, Mohsen
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Jonsson, Lage
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Jönsson, Pär
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Significance of Fluid Bypassing Effect on Darcy and Non-Darcy Permeability Parameters of Ceramic Foam FiltersManuscript (preprint) (Other academic)
  • 3037.
    Akbarnejad, Shahin
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Saffari Pour, Mohsen
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Jonsson, Lage Tord Ingemar
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Jönsson, Pӓr Göran
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Effect of Fluid Bypassing on the Experimentally Obtained Darcy and Non-Darcy Permeability Parameters of Ceramic Foam Filters2017In: Metallurgical and materials transactions. B, process metallurgy and materials processing science, ISSN 1073-5615, E-ISSN 1543-1916, Vol. 48, no 1, p. 197-207Article in journal (Refereed)
    Abstract [en]

    Ceramic foam filters (CFFs) are used to remove solid particles and inclusions from molten metal. In general, molten metal which is poured on the top of a CFF needs to reach a certain height to build the required pressure (metal head) to prime the filter. To estimate the required metal head, it is necessary to obtain permeability coefficients using permeametry experiments. It has been mentioned in the literature that to avoid fluid bypassing, during permeametry, samples need to be sealed. However, the effect of fluid bypassing on the experimentally obtained pressure gradients seems not to be explored. Therefore, in this research, the focus was on studying the effect of fluid bypassing on the experimentally obtained pressure gradients as well as the empirically obtained Darcy and non-Darcy permeability coefficients. Specifically, the aim of the research was to investigate the effect of fluid bypassing on the liquid permeability of 30, 50, and 80 pores per inch (PPI) commercial alumina CFFs. In addition, the experimental data were compared to the numerically modeled findings. Both studies showed that no sealing results in extremely poor estimates of the pressure gradients and Darcy and non-Darcy permeability coefficients for all studied filters. The average deviations between the pressure gradients of the sealed and unsealed 30, 50, and 80 PPI samples were calculated to be 57.2, 56.8, and 61.3 pct. The deviations between the Darcy coefficients of the sealed and unsealed 30, 50, and 80 PPI samples found to be 9, 20, and 31 pct. The deviations between the non-Darcy coefficients of the sealed and unsealed 30, 50, and 80 PPI samples were calculated to be 59, 58, and 63 pct.

  • 3038.
    Akbarpour, S.
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering.
    Hallström, S.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering.
    Metal reinforcement around fastener holes in composites2016In: ECCM 2016 - Proceeding of the 17th European Conference on Composite Materials, European Conference on Composite Materials, ECCM , 2016Conference paper (Refereed)
    Abstract [en]

    One way of improving the load capacity of bolted joints in composite components is to use metal inserts locally at the holes in order to reduce the bearing stress. In this paper an innovative local reinforcement concept is introduced where metal inserts are implemented in the form of stacked patches at the holes in order to improve the bearing strength of the composite. After doing some initial tests and a parameter study, some specimens with optimized stacked patch inserts were designed and tested. The specimens with optimized inserts show 50-60% improved bearing strength in pin-loaded tests which corresponds to a potential weight reduction of about 30%. These very promising results indicates that the efficiency of joints in composites can be improved significantly.

  • 3039.
    Akbary, Amir
    et al.
    Univ Lethbridge, Dept Math & Comp Sci, 4401 Univ Dr, Lethbridge, AB T1K 3M4, Canada..
    Parks, James
    KTH, School of Engineering Sciences (SCI), Mathematics (Dept.), Mathematics (Div.). Univ Lethbridge, Dept Math & Comp Sci, 4401 Univ Dr, Lethbridge, AB T1K 3M4, Canada.
    On the Lang-Trotter conjecture for two elliptic curves2019In: Ramanujan Journal, ISSN 1382-4090, Vol. 49, no 3, p. 585-623Article in journal (Refereed)
    Abstract [en]

    Following Lang and Trotter, we describe a probabilistic model that predicts the distribution of primes p with given Frobenius traces at p for two fixed elliptic curves over Q. In addition, we propose explicit Euler product representations for the constant in the predicted asymptotic formula and describe in detail the universal component of this constant. A new feature is that in some cases the l-adic limits determining the l-factors of the universal constant, unlike the Lang-Trotter conjecture for a single elliptic curve, do not stabilize. We also prove the conjecture on average over a family of elliptic curves, which extends the main results of Fouvry and Murty (Supersingular primes common to two elliptic curves, number theory (Paris, 1992), London Mathematical Society Lecture Note Series, vol 215, Cambridge University Press, Cambridge, 1995) and Akbary et al. (Acta Arith 111(3):239-268, 2004), following the work of David et al. (Math Ann 368(1-2):685-752, 2017).

  • 3040. Akbarzadeh, Sara
    et al.
    Combes, Richard
    KTH, School of Electrical Engineering (EES), Automatic Control.
    Altman, Zwi
    Self-organizing femtocell offloading at the flow level2013In: International Journal of Network Management, ISSN 1055-7148, E-ISSN 1099-1190, Vol. 23, no 4, p. 259-271Article in journal (Refereed)
    Abstract [en]

    Femtocell technology is expected to be fully self-managed, empowered by self-organizing network functionalities. This paper proposes a solution for self-optimized offloading of macrocell traffic towards open/hybrid-access femtocells. A heterogeneous network comprising macro- and femtocells is modeled as parallel queues. The coverage area of the femtocells is self-optimized by dynamically adapting their pilot powers. A simple update equation for the pilot power is given and its convergence is studied using stochastic approximation techniques. The algorithm balances the load among the cells to improve network capacity. Simulation results illustrate the important performance gains brought about by the proposed scheme, using a dynamic network simulator.

  • 3041. Akcay, H.
    et al.
    Hjalmarsson, Håkan
    Department of Electrical Engineering, Linköping University.
    Ljung, Lennart
    Department of Electrical Engineering, Linköping University.
    On the choice of norms in system identification1996In: IEEE Transactions on Automatic Control, ISSN 00189286 (ISSN), Vol. 41, no 9, p. 1367-1372Article in journal (Refereed)
    Abstract [en]

    In this paper we discuss smooth and sensitive norms for prediction error system identification when the disturbances are magnitude bounded. Formal conditions for sensitive norms, which give an order of magnitude faster convergence of the parameter estimate variance, are developed. However, it also is shown that the parameter estimate variance convergence rate of sensitive norms is arbitrarily bad for certain distributions. A necessary condition for a norm to be statistically robust with respect to the family F(C) of distributions with support [-C, C] for some arbitrary C > 0 is that its second derivative does not vanish on the support. A direct consequence of this observation is that the quadratic norm is statistically robust among all ℓp-norms, p ≀ 2 < ∞ for F(C). ©1996 IEEE.

  • 3042.
    Akdis, M
    et al.
    SIAF, Switzerland.
    Verhagen, J
    SIAF, Switzerland.
    Taylor, A
    SIAF, Switzerland.
    Karamloo, F
    SIAF, Switzerland.
    Karagiannidis, C
    SIAF, Switzerland.
    Crameri, R
    SIAF, Switzerland.
    Thunberg, Sarah
    Karolinska Institutet.
    Deniz, G
    SIAF, Switzerland.
    Valenta, R
    SIAF, Switzerland.
    Fiebig, H
    SIAF, Switzerland.
    Kegel, C
    SIAF, Switzerland.
    Disch, R
    SIAF, Switzerland.
    Schmidt-Weber, C B
    SIAF, Switzerland.
    Blaser, K
    SIAF, Switzerland.
    Akdis, C A
    SIAF, Switzerland.
    Immune responses in healthy and allergic individuals are characterized by a fine balance between allergen-specific T regulatory 1 and T helper 2 cells2004In: Journal of Experimental Medicine, ISSN 0022-1007, E-ISSN 1540-9538, Vol. 199, no 11, p. 1567-1575Article in journal (Refereed)
    Abstract [en]

    The mechanisms by which immune responses to nonpathogenic environmental antigens lead to either allergy or nonharmful immunity are unknown. Single allergen-specific T cells constitute a very small fraction of the whole CD4(+) T cell repertoire and can be isolated from the peripheral blood of humans according to their cytokine profile. Freshly purified interferon-gamma-, interleukin (IL)-4-, and IL-10-producing allergen-specific CD4(+) T cells display characteristics of T helper cell (Th)1-, Th2, and T regulatory (Tr)1-like cells, respectively. Tr1 cells consistently represent the dominant subset specific for common environmental allergens in healthy individuals; in contrast, there is a high frequency of allergen-specific IL-4-secreting T cells in allergic individuals. Tr1 cells use multiple suppressive mechanisms, IL-10 and TGF-beta as secreted cytokines, and cytotoxic T lymphocyte antigen 4 and programmed death 1 as surface molecules. Healthy and allergic individuals exhibit all three allergen-specific subsets in different proportions, indicating that a change in the dominant subset may lead to allergy development or recovery. Accordingly, blocking the suppressor activity of Tr1 cells or increasing Th2 cell frequency enhances allergen-specific Th2 cell activation ex vivo. These results indicate that the balance between allergen-specific Tr1 cells and Th2 cells may be decisive in the development of allergy.

  • 3043.
    Akdogan, Mariam
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Technology and Design.
    Baghdo, Gabriella
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Technology and Design.
    Utvärdering och effektivisering av byggprocessen på Projektgaranti AB2012Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The ame of this examination thesis is to evaluate the operation system at the company Projektgaranti AB and find different approaches and solutions on how to streamline the construction process. The purpose of evaluating the operational system is to get an understanding of Projektgaranti ABs way to work and investigate the use of the system.To carry out this study, we determined three different methods of evaluation that must be done in order to get a broad perspective at the opportunities that the system has to develop. This took the form of sample survey based on five selected projects from the company server. After that a questionnaire was sent out to all employees of the company in Stockholm and Gothenburg. Based on the answers we received we selected two employees from each office to be interviewed.The evaluation result shows the employees' opinions about the system, various improvement and development.To make the construction process more efficient is based on various research techniques. The one which we found to be most profitable for the company's development was the Lean Production, which includes showing different types of waste that can be avoided, how to create value and better planning. If you do it visually and include teamwork and commitment it will lead to a more efficient construction.

  • 3044. Akerman, J. J.
    et al.
    Venturini, E. L.
    Siegal, M. P.
    Yun, S. H.
    Karlsson, U. O.
    Rao, K. V.
    KTH, Superseded Departments, Materials Science and Engineering.
    Two-stage crossover from thermal to quantum flux creep of dilute vortex ensembles in various high-T-c superconducting thin films2001In: Physical Review B Condensed Matter, ISSN 0163-1829, E-ISSN 1095-3795, Vol. 64, no 9Article in journal (Refereed)
    Abstract [en]

    The thermal-to-quantum flux creep crossover at low vortex densities has been studied in YBa2Cu3O7, TlBa2CaCu2O7-delta, and HgBa2CaCu2O6+delta thin films using ac susceptibility. The crossover temperatures T-cr are 10-11, 17, and 30 K, respectively. Both thermal and quantum flux creep is suppressed as the vortex density is decreased. We observe a two-stage nature in the crossover behavior which appears to be a general property of all the three materials studied.

  • 3045. Akerman, J. J.
    et al.
    Yun, S. H.
    Karlsson, U. O.
    Rao, K. V.
    KTH, Superseded Departments, Materials Science and Engineering.
    Dislocation-mediated creep of highly separated vortices in a-axis-oriented HgBa2CaCu2O6+delta thin films2001In: Physical Review B Condensed Matter, ISSN 0163-1829, E-ISSN 1095-3795, Vol. 64, no 2Article in journal (Refereed)
    Abstract [en]

    Using ac susceptibility, we determine the critical current density J(c) and the flux creep activation energy U of an a-axis-oriented HgBa2CaCu2O6+delta thin film. The critical current density at helium temperatures is found to be 4.6 x 10(4) A/cm(2), i.e., about two orders of magnitude smaller than for corresponding films with c-axis orientation. The temperature and ac field dependent activation energy is consistent with dislocation-mediated flux creep and well described by U(T,H-ac)=U-o(1-t(4))H-ac(-1/2) with t=T/T-c, T-c=120K, and U-o = 0.77 eV Oe(1/2) for temperatures T>45 K and in the field range studied. The activation energy is of the same order as that found in c-axis-oriented films. Below T = 45 K the activation energy is observed to decrease as thermally assisted quantum creep becomes increasingly important.

  • 3046. Akesson, M.
    et al.
    Gustafsson, E.
    Johansson, Karl Henrik
    Control design for a helicopter lab process1996Conference paper (Refereed)
  • 3047.
    Akeyo Forsman, Prisca
    KTH, School of Industrial Engineering and Management (ITM), Applied Mechanical Engineering (KTH Södertälje).
    A Study of Construction Project Stakeholders’ Management Methods and the Critical Success Factors Essential for Successful Management in Stockholm Region.2017Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
  • 3048.
    Akfidan, Johny
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Sadek, Rafed
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Dimensionering och utförande av bottenplattor utsatta för upptryck2012Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [sv]

    När en konstruktion byggs på det viset att dess bottenplatta hamnar under grundvattenytan, skapas ett grundvattentryck upp mot bottenplattan och konstruktionen, som kan åstadkomma stora problem. Grundvattnet, som tryckts undan av konstruktionen, vill nå upp till sin ursprungliga nivå och därmed trycka med sig konstruktionen upp. Detta fenomen kallas hydraulisk bottenupptryckning. Fenomenet kan motverkas på olika sätt, där rapporten beaktar två olika sätt att motverka hydraulisk bottenupptryckning på: genom en bottenplatta som är tyngre än grundvattentrycket eller förankra bottenplattan mot ett fast underlag.

    Genom att uppmärksamma och sammanställa projekt (huvudsakligen konstruerade av Tyréns) som tagit hänsyn till ovan nämnda fenomen vid dimensioneringen av bottenplattan, har en rapport skapats. Denna rapport ska finnas för att åstadkomma kunskapsåterföring av de problem som uppstått i projekten och deras lösningar.

    Utöver att skapa en rapport där de berörda projekten sammanställs ska en bottenplatta optimeras, huvudsakligen med hänseende till bottenplattans tjocklek och dess bärförmåga mot genomstansning för olika förankringstyper. Optimeringen ska ske i enlighet med, huvudsakligen Eurokod 2 kapitlen 6.4 och 7.3. Det har bestämts att tre tjocklekar på bottenplattan ska beaktas, och dessa är 400, 550 och 800 mm. Genom diskussioner med våra handledare, sakkunnig personal på Tyréns och representanter inom branschen, valdes ett antal förankringstyper som skulle jämföras. För att kunna jämföra kombinationerna av de olika tjocklekarna på bottenplattan och de olika förankringstyperna, har Tyréns projekt Biomedicum med dess förutsättningar, utnyttjats som referensobjekt.

    Att ta fram de inre krafterna i bottenplattan via handberäkningar är mycket komplicerat och tidskrävande för att rymmas inom ramen för denna studie. Därför används programmet FEM Plate (Strusoft) för att ta fram dessa krafter. De inre krafter som tas fram från FEM Plate utnyttjas sedan för att med hjälp av handberäkningar, i enlighet Eurokod 2, dimensionera Biomedicums bottenplatta enligt de moment som krävs.

    Jämförelsen av de olika kombinationerna visar på att bottenplattan 400 mm med förankringstypen stålkärna av diameter 80 mm från Inexa Profil är den optimala lösningen för Biomedicums bottenplatta. Denna förankringstyp (för bottenplattan 400 mm) är den enda som får en tillräcklig bärförmåga mot genomstansning av bottenplattan, endast med åtgärden skjuvarmering runtomkring förankringen.

    En föreslagen lösning på hur förankringstypen bör monteras i bottenplattan har tagits fram. Diskussioner med sakkunnig personal från Minova (tillverkare av MAI-förankringen) har lett till övertygelsen om att föreslagen lösning fungerar utan några kapacitetsförsämringar på förankringen. En modellering av bottenplattan 400 mm med föreslagen lösning på MAIförankringen och efterföljande handberäkningar, visar att lösningen optimerar bottenplattan än mer. föreslagen lösning på monteringen i bottenplattan bör dessutom kunna tillämpas på de andra förankringstyperna, men har endast beaktats för MAI-förankringen.

    Eftersom fokus endast är på att den optimala bottenplattan är 400 mm och ingen hänsyn tas till kostnaderna, är föreslagen lösning på MAI-staget den optimala lösningen. Det är den enda förankringen som har en tillräcklig bärförmåga mot genomstansning för bottenplattan 400 mm, utan några som helst extra åtgärder.

    En bottenplatta med vot under förankringen bör undvikas, eftersom förtjockningen av bottenplattan under förankringen kräver mycket extra tid i utförande. Därför rekommenderas det att en jämntjock bottenplatta dimensioneras med eventuell skjuvarmering, om bottenplattans bärförmåga mot genomstansning inte är tillräcklig utan skjuvarmering.

    Den optimering som tagits fram är en generalisering av Biomedicums bottenplatta. Detta leder till att de modeller och beräkningar som gjorts, enkelt kan implementeras på andra bottenplattor med samma problem genom att justera indata.

  • 3049.
    Akhand, Victoria
    KTH, School of Chemical Science and Engineering (CHE).
    Mass Balance Model of Impurities for the WoodRoll Process2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The depletion time for fossil fuels calculated from 2009 is 35 years for oil, 37 years for gas

    and 107 years for coal. Hence, it has become essential to reduce the dependence on fossil

    fuels by switching over to renewable resources. This in turn will also help in combating the

    negative effects on the environment like global warming. Thermochemical processes such as

    pyrolysis and gasification of biomass are considered the most efficient technology for

    converting biomass to useful energy carriers. Cortus Energy AB is a Swedish company that

    has developed a patented gasification technology called WoodRoll

    ® for gasification of fuels derived from biomass. However, ash in a thermochemical conversion process can cause

    corrosion, sintering, slag and poisoning of catalysts, which leads to operational problems. In

    addition, heavy metals such as Zn, Pb and Cd are environmentally problematic. These metals

    contribute to environmental pollution by contaminating the soil, which in turn can harm

    humans and the ecosystem via the food chain. The undesired elements should therefore be

    identified to minimize their impact on the overall thermochemical process and to reduce the

    emission of these harmful substances.

    The objective of this master thesis project, on behalf of Cortus Energy AB, was to investigate

    possible key numbers that can be used to describe and predict how the ash behaves in their

    patented WoodRoll® process. The key numbers that have been identified are empirically

    developed based on experience of coal combustion. These key numbers are regularly used for

    fuel derived from biomass by companies specializing in analyzing, although knowledge about

    whether they can actually be used on biomass is limited. In order to ensure that the use of

    these for biomass is correct, they must be experimentally verified in the future. In addition, a

    theoretical investigation is conducted to study which species can form and in what phase this

    occurs. The investigation reveals that there are no clear trends for how the inorganic elements

    behave since contradicting results from different studies have been reported. Formation of

    species and their phase depends on several parameters such as temperature, heating rate,

    particle size, volatility, quantity and interaction between the elements in the biomass. The

    thesis project ends with a mass balance model on selected inorganic elements for wood

    residues, as well as for bark. The model could be a tool for Cortus Energy AB to identify

    approximately how much of each element is present in each stream in the WoodRoll® process.

    The models are verified with analysis results. Inorganic elements that affect the

    overall process and its equipment have been selected for modelling. The volume percent of

    H2, CO, CO2 and CH4 in the models agree well with the values obtained by Cortus Energy

    AB. This shows that the thermodynamic equilibrium calculations performed are reasonable.

  • 3050.
    Akhand, Victoria
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Celsi, Adrian
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Lagerberg, Tove
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Sångberg, Oscar
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Plastfilm från rapshalm2015Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The purpose of this project is to extract hemicellulose from the rape straw by using alkali- and water extraction, and thereafter to produce a film with these polymers. The intention with this film is to eventually replace the present oxygen barrier made of aluminium in applications such as food packaging made of cardboard, among other things. The film is composed of hemicellulose and additives, either the CMC or sorbitol molecules. Many analyses were conducted on the extracts and the films in order to draw conclusions about the structure and properties. The NMR analysis showed that the extracts contained the expected sugars and that the main deacetylation of O-acetyl groups happened during the extraction with low alkali. The SEC analysis gave low values of Đ. The tensile testing gave exceptional results, namely elongations of 10-60%, depending on the composition of the films. Two of the most significant analyses are the ion chromatography and the oxygen permeability test, which could not be implemented because of technical difficulties. Low alkali is to be preferred as solvent, used to extract the polymers, with respect to the environment, the economy and the mechanical properties. Furthermore, high addition of CMC is preferred when producing films because low CMC and sorbitol resulted in sticky films. For future work it would be recommended to analyse the films by conducting the ion chromatography and the oxygen permeability test. Additionally, it would be desirable to find the optimal addition amount of the CMC.

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