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  • 201.
    Andersson, Staffan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Physics Didactics.
    A conference as examination: Meeting a professional scientist culture2008In: Presentation at the Scholarship of University Teaching and Learning National Workshop III - Teachers developing their practice using science education research, Göteborg, Sweden, 23-24 October, 2008Conference paper (Other academic)
  • 202.
    Andersson, Staffan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Physics Didactics.
    Acquisition of a collection in context: A case study of the Uppsala Cabinet of Physics2006In: Proceedings of the XXV Scientific Instrument Symposium: East and West, The Common European Heritage / [ed] Ewa Wyka, Maciej Kluza, Anna Karolina Zawada, 2006Conference paper (Refereed)
  • 203.
    Andersson, Staffan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Physics Didactics.
    Bitar av en lärarroll: "Jag är lite som ett utrotningshotat djur - jag är fysiklärare."2015In: LMNT-nytt, ISSN 1402-0041, no 1, p. 8-10Article in journal (Other (popular science, discussion, etc.))
  • 204.
    Andersson, Staffan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Physics Didactics.
    Conference as examination: Meeting a professional scientist culture2008Conference paper (Other academic)
  • 205.
    Andersson, Staffan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Physics Didactics.
    Experimentalfysiken - Motiven bakom 1700-talets förändrade fysikundervisning2007Other (Other (popular science, discussion, etc.))
  • 206.
    Andersson, Staffan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Physics Didactics.
    'Fysikshow?' eller 'Varför måste fysik alltid vara så roligt?'2007In: Presentation at "Fysikdagarna 2007", Uppsala Universitet, 29-30 October., 2007Conference paper (Other (popular science, discussion, etc.))
  • 207.
    Andersson, Staffan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Physics Didactics.
    Hur ger man civilingenjörsstudenter positiva upplevelser av utbildningens första termin?2008Conference paper (Other academic)
  • 208.
    Andersson, Staffan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Physics Didactics.
    Hur tänker studenterna? Växelspelet mellan individer och utbildningsdiskursen.2008Other (Other academic)
  • 209.
    Andersson, Staffan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Physics Didactics.
    Physics Education in Sweden: An Overview2008In: Presentation at the European Committee for Future Accelerators R-ECFA Meeting, Uppsala, Sweden, 9-10 May, 2008Conference paper (Other academic)
  • 210.
    Andersson, Staffan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Physics Didactics.
    Undervisning och lärande ur ett identitetsperspektiv2008In: Presentation to the 'Mentorskollegiet', Uppsala University, 16 October, 2008Conference paper (Other academic)
  • 211.
    Andersson, Staffan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Physics Didactics.
    Using Historical Collections when Teaching a Broadened Science Curriculum2008In: Rittenhouse - The Journal of the American Scientific Enterprise, Vol. 22, no 2, p. 114-131Article in journal (Refereed)
  • 212.
    Andersson, Staffan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Physics Didactics. Fysikens didaktik.
    Using Historical Collections when Teaching a Broadened Science Curriculum.2007In: International Workshop on Historic Scientific Instrument Collections in the University, Oxford, Mississippi, 2007Conference paper (Refereed)
  • 213.
    Andersson, Staffan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Physics Didactics.
    Andersson Chronholm, Jannika
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Physics Didactics.
    Retentionsbefrämjande introduktionskurs till universitetsstudier.2010Conference paper (Other academic)
    Abstract [sv]

    Studenters första tid vid universitetet är mycket viktig, då forskningen betonar att grunden läggs för studenternas fortsatta lärande och deras retention inom högre utbildning. Samtidigt är det en period då många studenter avbryter sina studier. I Sverige har mer än 10 % av nybörjarna på utbildningsprogram försvunnit till den andra terminen (SCB, 2009).

    På basårsutbildningen vid Uppsala universitet fortsatte omkring 80 % av nybörjarna till utbildningens andra termin (2002-2007). Förlusten av studenter förklarades först med att studenterna var ”svaga” och en kurs i studieteknik introducerades hösten 2007. Ingen skillnad sågs dock för studentretentionen till våren 2008.

    Höstterminen 2008 infördes därför en nyutvecklad delkurs – Introduktion till universitetsstudier. Kursen tar ett bredare grepp och baseras på forskning kring lärande och retention inom högre utbildning. Studenters beslut att avbryta sina studier har visat sig till stor del bero på växelspelet mellan dem och deras upplevelse av universitetsmiljön och yttre faktorer (se exempelvis Cabrera, Castaneda, Nora & Hengstler, 1992). De bakomliggande upplevelserna kan sägas vara av fyra olika slag (Yorke & Longden, 2004). Studenter som lämnat utbildningen har upplevt att de:

    1)      inte valt rätt utbildning. 2) inte klarar av utbildningen. 3) inte passar in på utbildningen. 4) måste lämna utbildningen på grund av yttre faktorer.

    Den tidigare kursen i studieteknik hade som utgångspunkt att studenterna hade problem att klara av utbildningen, vilket delvis berör andra punkten. I utformningen den nya kursen utgick vi från alla dessa punkter, men med en tonvikt på den andra och tredje.

    Introduktionskursens främsta mål blev att underlätta studenternas introduktion till universitetet, synliggöra aspekter av den universitetstypiska studiekulturen och få dem att känna tillhörighet. Studenterna arbetade också med uppläggningen för sina fortsatta studier samt studieteknik kopplad till andra delkurser.

    Den nya kursens mål, att öka studentretentionen, lyckades över förväntan. Av de nybörjare som deltog i introduk­tionskursen 2008 eller 2009 fortsatte 94 % till vårterminen. För de 117 nybörjare som valde att inte läsa kursen är mot­svarande siffra 78 %.

    I presentationen kommer vi att ge en kort översikt av bakomliggande forskning, presentera vårt kursupplägg och diskutera kursens effekter.

    Referenser

    Cabrera, A. F., Castaneda, M. B., Nora, A. & Hengstler, D. (1992). The Convergence between Two Theories of College Persistence. Journal of Higher Educ.,63(2), 143-164.

    SCB (2009) Utbildningsstatistisk årsbok 2010 Tabeller, Örebro:SCB

    Yorke, M. & Longden, B. (2004). Retention and Student Success in Higher Education. Glasgow: Open University Press.

  • 214.
    Andersson, Staffan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Physics Didactics.
    Forsman, Jonas
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Physics Didactics.
    Linder, Cedric
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Physics Didactics.
    ”Det löser sig under studiernas gång”2010Conference paper (Other academic)
    Abstract [sv]

    Studenters förhållningssätt till högre studier präglas allt mer av identitetsbekräftelse (Schreiner, 2006) och utbildningskon­sumtion (Friis Johannsen, 2007). För många är studierna ett medel för att utveckla eller manifestera en identitet. Schrei­ner (2006) sammanfattar: When young people choose an education or profession, they express at the same time key components of their identity.

    Andelen nybörjarstudenter som tagit civilingenjörsexamen efter fem år halverades från 38% i 1980-talets mitt till 19% vid 2000-talets början. Andelen som tagit examen efter sju år har däremot bara minskat från 60% till 55%. Idag tar alltså nästan lika många studenter en civilingenjörsexamen, men de tar längre tid på sig. Med resultat från olika studier vill vi illustrera hur det förändrade förhållningssättet bidrar till att det tar allt längre tid för civilingenjörsstudenter att nå sin examen. Att finna ett yrke har för många blivit något som ”löser sig under studiernas gång”.

    En enkätstudie för nybörjare på ett civilingenjörsprogram i teknisk fysik visade att 65 % hade som främsta mål att just gå utbildningen. Övriga hade mer långsiktiga mål, som exempelvis yrkesarbete.

    Flera studenter uttrycker en osäkerhet i att välja rätt i det stora utbildningsutbudet med fler än 65 olika civilingenjörs­program och otaliga andra utbildningar att välja på. Ett sätt att hanterar detta utbud är mobilitet mellan utbildningar.

    Analys av studiebanor för en kull på teknisk fysik från 2006 visade att 30 % av studenterna läst vid andra utbildnings-program tidigare och/eller lämnade programmet för att läsa ett annat.

    En intervjustudie visade att många av studenterna ansåg att det inledningsvis var minst lika viktigt att engagera sig i kår, studentliv och annat för att utveckla sig som person. Senare under studietiden kunde man fokusera sig, hitta en inriktning och avsluta studierna.

    Den inriktning som studenterna vill ha finns inte alltid inom civilingenjörsprogrammens struktur. Därför väljer de att bredda sig med andra kurser, exempelvis i ekonomi, språk, juridik och datavetenskap.

    Detta är några faktorer som bidrar till att tiden som studenterna behöver för att nå sin civilingenjörsexamen ökar. Dagens studenter läser allt oftare främst för att ”bli någon” och det är något som ofta tar både längre tid och andra vägar än vad de som planerat utbildningarna förväntat sig.

    Referenser

    Friis Johannsen, B. (2007). Attrition in University Physics. Uppsala University, Uppsala.

    Schreiner, C. (2006) EXPLORING A ROSE-GARDEN Norwegian youth’s orientations towards science – seen as signs of late modern identities. Oslo University, Oslo.

  • 215.
    Andersson, Staffan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Physics Didactics.
    Linder, Cedric
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Physics Didactics.
    Motives and achievements of first year students in the masters programme in Engineering Physics at Uppsala University2008In: Paper presented at the Engineering Education Development Conference, Royal Institute of Technology, Stockholm, Sweden, 26-27 November., 2008Conference paper (Refereed)
  • 216.
    Andersson, Staffan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Physics Didactics.
    Linder, Cedric
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Physics Didactics.
    Relations between motives, academic achievement and retention in the first year of a master programme in Engineering Physics.2010In: Contemporary Science Education Research: Learning and Assessment. / [ed] G. Çakmakci & M. F. Tasar, Ankara: Pegem Akademi. , 2010, p. 123-128Chapter in book (Other academic)
  • 217.
    Andersson, Staffan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Physics Didactics.
    Linder, Cedric
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Physics Didactics.
    Relations between motives, academic achievement and retention in the first year of a master programme in Engineering Physics2009In: Paper presented at the ESERA (European Science Education Research Association) Conference, Istanbul, Turkey, 31 August - 4 September, 2009Conference paper (Refereed)
  • 218.
    Andisheh, Bahram
    Stockholm University, Faculty of Science, Department of Physics.
    Improving the therapeutic ratio of stereotactic radiosurgery and radiotherapy2012Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    New methods of high dose delivery, such as intensity modulated radiation therapy (IMRT), stereotactic radiation therapy (SRT) or stereotactic radiosurgery (SRS), hadron therapy, tomotherapy, etc., all make use of a few large fractions. To improve these treatments, there are three main directions: (i) improving physical dose distribution, (ii) optimizing radiosurgery dose-time scheme and (iii) modifying dose response of tumors or normal tissues.

    Different radiation modalities and systems have been developed to deliver the best possible physical dose to the target while keeping radiation to normal tissue minimum. Although applications of radiobiological findings to clinical practice are still at an early stage, many studies have shown that   sublethal radiation damage repair kinetics plays an important role in tissue response to radiation.

    The purpose of the present thesis is to show how the above-mentioned directions could be used to improve treatment outcomes with special interest in radiation modalities and dose-time scheme, as well as radiobiological modeling. Also for arteriovenous malformations (AVM), the possible impact of AVM network angiostructure in radiation response was studied.

  • 219.
    Andresen, Juan Carlos
    et al.
    KTH, School of Engineering Sciences (SCI), Theoretical Physics, Condensed Matter Theory. Theoretische Physik, ETH Zurich, Zurich, Switzerland.
    Pramudya, Yohanes
    Katzgraber, Helmut G.
    Thomas, Creighton K.
    Zimanyi, Gergely T.
    Dobrosavljevic, V.
    Charge avalanches and depinning in the Coulomb glass: The role of long-range interactions2016In: Physical Review B, ISSN 2469-9950, Vol. 93, no 9, article id 094429Article in journal (Refereed)
    Abstract [en]

    We explore the stability of far-from-equilibrium metastable states of a three-dimensional Coulomb glass at zero temperature by studying charge avalanches triggered by a slowly varying external electric field. Surprisingly, we identify a sharply defined dynamical ("depinning") phase transition from stationary to nonstationary charge displacement at a critical value of the external electric field. Using particle-conserving dynamics, scale-free system-spanning avalanches are observed only at the critical field. We show that the qualitative features of this depinning transition are completely different for an equivalent short-range model, highlighting the key importance of long-range interactions for nonequilibrium dynamics of Coulomb glasses.

  • 220. Andreyev, A. N.
    et al.
    Huyse, M.
    Van Duppen, P.
    Qi, Chong
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Liotta, Roberto J.
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Antalic, S.
    Ackermann, D.
    Franchoo, S.
    Heßberger, F. P.
    Hofmann, S.
    Kojouharov, I.
    Kindler, B.
    Kuusiniemi, P.
    Lesher, S. R.
    Lommel, B.
    Mann, R.
    Nishio, K.
    Page, R. D.
    Streicher, B.
    Šáro, Š.
    Sulignano, B.
    Wiseman, D.
    Wyss, Ramon A .
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Signatures of the Z=82 shell closure in alpha-decay process2013In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 110, no 24, article id 242502Article in journal (Refereed)
    Abstract [en]

    In recent experiments at the velocity filter Separator for Heavy Ion reaction Products (SHIP) (GSI, Darmstadt), an extended and improved set of α-decay data for more than 20 of the most neutron-deficient isotopes in the region from lead to thorium was obtained. The combined analysis of this newly available α-decay data, of which the Po186 decay is reported here, allowed us for the first time to clearly show that crossing the Z=82 shell to higher proton numbers strongly accelerates the α decay. From the experimental data, the α-particle formation probabilities are deduced following the Universal Decay Law approach. The formation probabilities are discussed in the framework of the pairing force acting among the protons and the neutrons forming the α particle. A striking resemblance between the phenomenological pairing gap deduced from experimental binding energies and the formation probabilities is noted. These findings support the conjecture that both the N=126 and Z=82 shell closures strongly influence the α-formation probability.

  • 221. Andrievsky, Alexander
    et al.
    Brandenburg, Axel
    KTH, Centres, Nordic Institute for Theoretical Physics NORDITA. Department of Astronomy, Stockholm University, AlbaNova University Center, Stockholm, Sweden.
    Noullez, Alain
    Zheligovsky, Vladislav
    Negative magnetic eddy diffusivities from the test-field method and multiscale stability theory2015In: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 811, no 2, article id 135Article in journal (Refereed)
    Abstract [en]

    The generation of a large-scale magnetic field in the kinematic regime in the absence of an alpha-effect is investigated by following two different approaches: the test-field method and the multiscale stability theory relying on the homogenization technique. Our computations of the magnetic eddy diffusivity tensor of the parity-invariant flow IV of G. O. Roberts and the modified Taylor-Green flow confirm the findings of previous studies. and also explain some of their apparent contradictions. The two flows have large symmetry groups; this is used to considerably simplify the eddy diffusivity tensor. Finally, a new analytic result is presented: upon expressing the eddy diffusivity tensor in terms of solutions to auxiliary problems for the adjoint operator, we derive relations between the magnetic eddy diffusivity tensors that arise for mutually reverse small-scale flows v(x) and - v(x).

  • 222.
    Anghel, Ionut Gheorghe
    et al.
    KTH, School of Engineering Sciences (SCI), Physics, Reactor Technology.
    Anglart, Henryk
    KTH, School of Engineering Sciences (SCI), Physics, Reactor Technology.
    Post-dryout heat transfer to high-pressure water flowing upward in vertical channels with various flow obstacles2012In: International Journal of Heat and Mass Transfer, ISSN 0017-9310, E-ISSN 1879-2189, Vol. 55, no 25-26, p. 8020-8031Article in journal (Refereed)
    Abstract [en]

    Post-dryout heat transfer to high pressure water was investigated experimentally in vertical tubes and annuli containing various flow obstacles. The operational conditions during the experiments were as follows: mass flux from 500 to 1750 kg/m(2) s. pressure from 5 to 9 MPa, inlet subcooling from 10 to 40K and heat flux up to 1.5 MW/m(2). Five different test sections were used in experiments: three annular test sections with inner diameter 12.7 mm and outer diameter 24.3 mm, containing cylindrical and grid flow obstacles in the upper part, and two tubular test sections with inner diameter 24.3 mm with and without pin flow obstacles. The heated length in all test sections was 3650 mm. The wall temperature was measured with 88 thermocouples located along the inner rod and the outer tube surfaces. Due to the presence of flow obstacles, only developing post-dryout heat transfer was observed. Selected post-dryout heat transfer correlations were compared to the experimental data. It has been concluded that all tested correlations predict significantly higher wall temperatures than those obtained in the present experiment. A simple correction function to the Saha model has been suggested which significantly improves the agreement between the correlation and the present data.

  • 223.
    Anglart, Henryk
    KTH, School of Engineering Sciences (SCI), Physics, Reactor Technology.
    Numerical analysis of the onset of heat transfer deterioration to supercritical water2010In: International Congress on Advances in Nuclear Power Plants 2010, ICAPP 2010: Volume 3, 2010, p. 1689-1695Conference paper (Refereed)
    Abstract [en]

    In this paper the mechanism of the onset of heat transfer deterioration to supercritical water is elucidated with detailed numerical predictions of flow and heat transfer in the boundary layer. It is shown that for low mass flow rates the buoyancy effects are dominant and the deterioration of heat transfer is caused by the turbulence damping in the vicinity of the heated wall. For high mass flow rates the mechanism of deterioration changes and the triggering factor is the decrease of the thermal conductivity of fluid in the viscous sub-layer. A numerical prediction of this phenomenon requires application of a low Reynolds number turbulence model with y+ less than 1.

  • 224. Angyal, G.
    et al.
    Csepura, G.
    Balkay, L.
    Galuska, L.
    Molnár, J.
    Valastyán, I.
    PET examination in intracranial tumor diagnosis of a cat2008In: AIP Conference Proceedings, 2008, p. 199-203Conference paper (Refereed)
    Abstract [en]

    This paper shows the significance of the Positron Emission Tomography (PET) in the veterinary medication through a case study of a cat brain tumor. A castrated male cat with bilateral mydriasis and blindness arrived at the veterinary clinic. After physical, laboratory and neurological investigations other sickness was ruled out and the inkling of the intracranial lesion had come to light. Brain tumor seemed the most likely to cause the illness because other symptoms appeared (for example: anorexia, depression) and they progrediated fast. PET examination, using 18F-FDG isotope, was performed to confirm the possible causes of the cat's symptoms

  • 225. Anoushirvani, B.
    et al.
    Enström, Daniel
    Fredriksson, Sverker
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Hansson, Johan
    Ökvist, P.
    Nicolaidis, A.
    Ekelin, Svante
    Kungliga tekniska högskolan, KTH.
    Gamma-ray bursts from primordial quark objects in space1997In: Proceedings of the Joint Meeting of the Networks 'The Fundamental Structure of Matter' and 'Tests of the Electroweak Symmetry Breaking', Ouranoupolis, Greece, May 1997, 1997Conference paper (Refereed)
    Abstract [en]

    We investigate the possibility that gamma-ray bursts originate in a concentric spherical shell with a given average redshift and find that this is indeed compatible with the data from the third BATSE (3B) catalog. It is also shown that there is enough freedom in the choice of unknown burst properties to allow even for extremely large distances to the majority of bursts. Therefore, we speculate about an early, and very energetic, origin of bursts, and suggest that they come from phase transitions in massive objects of pure quark matter, left over from the Big Bang.

  • 226.
    Ansari, Nazanin
    et al.
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Khartsev, Sergiy
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Grishin, Alexander
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Multicolor filter all-garnet magneto-optical photonic crystals2012In: Optics Letters, ISSN 0146-9592, E-ISSN 1539-4794, Vol. 37, no 17, p. 3552-3554Article in journal (Refereed)
    Abstract [en]

    We demonstrate a multicolor optical filter and isolator based on a double-cavity magneto-optical (MO) photonic crystal. Being grown as a heteroepitaxial all-garnet multilayer, it compromises a strong MO response and high optical transmittance. Low-loss, high Faraday rotation passbands as well as strong light rejection within the stop band were achieved by optimization of distance between cavities and repetition number of distributed Bragg reflectors.

  • 227.
    Anselmino, M.
    et al.
    Dipertemento di Fisica Teoria, Universita di Torino and INFS.
    Boglione, M.
    Department of Physics and Astronomy, Vrije Universitet Amsterdam.
    Hansson, Johan
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Murgia, F.
    Institute Nazionale Fisica Nucleare, Seizone di Cagliari.
    Predictions for single spin asymmetries in ℓ parrow -> π X and γ * parrow -> π X2000In: European Physical Journal C, ISSN 1434-6044, E-ISSN 1434-6052, Vol. 13, no 3, p. 519-526Article in journal (Refereed)
    Abstract [en]

    Predictions for the single transverse spin asymmetry AN in semi-inclusive DIS processes are given; non-negligible values of AN may arise from spin effects in the fragmentation of a polarized quark into a final hadron with a transverse momentum ěc k⊥ with respect to the jet axis, the so-called Collins effect. The elementary single spin asymmetry of the fragmenting quark has been fixed in a previous paper, by fitting data on parrow p -> π X, and by assuming that the QCD factorization theorem holds also when transverse momenta are taken into account. The predictions given here are based on the assumption that the Collins effect is the only cause of the observed single spin asymmetries in parrow p -> π X. Eventual spin and ěc k⊥ dependences in the quark distribution functions, the so-called Sivers effect, are also discussed.

  • 228. Anselmino, M.
    et al.
    Boglione, Mariaelena
    Hansson, Johan
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Burgia, F.
    Inclusive production of hadrons in lepton (polarized) p (polarized) ---> h (polarized) X and spin measurements1996In: Proceedings of International Workshop on Deep Inelastic Scattering and Related Phenomena, DIS 96, 1996, p. 583-589Conference paper (Refereed)
    Abstract [en]

    We discuss the production of polarized hadrons in polarized lepton nucleon interactions and show that the helicity density matrix of the hadron, when measurable, can give information on the spin structure of the nucleon and the spin dependence of the quark fragmentation process. Single spin asymmetries in the $\ell N^\uparrow \to hX$ process are also briefly discussed.

  • 229. Anselmino, M.
    et al.
    Boglione, Mariaelena
    Hansson, Johan
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Murgia, F.
    Spin measurements in l p ---> h X deep inelastic scattering1997In: SPIN 96: proceedings; September 10-14, 1996, Amsterdam, the Netherlands, Singapore: World Scientific Publishing Co Pte Ltd , 1997, p. 346-348Conference paper (Refereed)
    Abstract [en]

    The production of hadrons in polarized lepton-nucleon deep inelastic scattering is discussed. The helicity density matrix of the hadron is computed within the QCD hard scattering formalism and its elements are shown to yield information on the spin structure of the nucleon and the spin dependence of the quark fragmentation process. The case of $\rho$ vector mesons is considered in more detail and estimates are given.

  • 230.
    Anselmino, Mauro
    Luleå tekniska universitet.
    Diquarks1992Report (Other academic)
  • 231.
    Anselmino, Mauro
    et al.
    Dipartimento di Fisica Teorica, Università di Torino and Istituto Nazionale di Fisica Nucleare, Sezione di Torino.
    Boglione, Maria
    Dipartimento di Fisica Teorica, Università di Torino and Istituto Nazionale di Fisica Nucleare, Sezione di Torino.
    Hansson, Johan
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Murgia, Francesco
    Istituto Nazionale di Fisica Nucleare, Sezione di Cagliari.
    Polarized inclusive leptoproduction, lN→hX, and the hadron helicity density matrix ρ(h): Possible measurements and predictions1996In: Physical Review D. Particles and fields, ISSN 0556-2821, E-ISSN 1089-4918, Vol. 54, no 1, p. 828-837Article in journal (Refereed)
    Abstract [en]

    We discuss the production of hadrons in polarized lepton-nucleon interactions and in the current jet fragmentation region; using the QCD hard scattering formalism we compute the helicity density matrix of the hadron and show how its elements, when measurable, can give information on the spin structure of the nucleon and the spin dependence of the quark fragmentation process. The cases of ρ vector mesons and Λ baryons are considered in more detail and, within simplifying assumptions, some estimates are given

  • 232.
    Anselmino, Mauro
    et al.
    Dipartimento di Fisica Teorica, Università di Torino and Istituto Nazionale di Fisica Nucleare, Sezione di Torino.
    Predazzi, Enrico
    Dipartimento di Fisica Teorica, Università di Torino and Istituto Nazionale di Fisica Nucleare, Sezione di Torino.
    Ekelin, Svante
    Kungliga tekniska högskolan, KTH.
    Fredriksson, Sverker
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Lichtenberg, D.B.
    Department of Physics, Indiana University.
    Diquarks1993In: Reviews of Modern Physics, ISSN 0034-6861, E-ISSN 1539-0756, Vol. 65, no 4, p. 1199-1233Article in journal (Refereed)
    Abstract [en]

    It is becoming increasingly clear that the concept of a diquark (a two-quark system) is important for understanding hadron structure and high-energy particle reactions. According to our present knowledge of quantum chromodynamics (QCD), diquark correlations arise in part from spin-dependent interactions between two quarks, from quark radial or orbital excitations, and from quark mass differences. Diquark substructures affect the static properties of baryons and the mechanisms of baryon decay. Diquarks also play a role in hadron production in hadron-initiated reactions, deep-inelastic lepton scattering by hadrons, and in e+e- reactions. Diquarks are important in the formation and properties of baryonium and mesonlike semistable states. Many spin effects observed in high-energy exclusive reactions pose severe problems for the pure quark picture of baryons and might be explained by the introduction of diquarks as hadronic constituents. There is considerable controversy, not about the existence of diquarks in hadrons, but about their properties and their effects. In this work a broad selection of the main ideas about diquarks is reviewed.

  • 233.
    Antipov, Sergey V.
    et al.
    Department of Chemistry and Molecular Biology, University of Gothenburg.
    Gustafsson, Magnus
    Department of Chemistry and Molecular Biology, University of Gothenburg.
    Nyman, Gunnar
    Department of Chemistry and Molecular Biology, University of Gothenburg.
    Isotope effect in the formation of carbon monoxide by radiative association2013In: Monthly notices of the Royal Astronomical Society, ISSN 0035-8711, E-ISSN 1365-2966, Vol. 430, no 2, p. 946-950Article in journal (Refereed)
    Abstract [en]

    Rate coefficients for the formation of 12CO and 13CO isotopologues of carbon monoxide by radiative association for T = 10–20 000 K are calculated using a quantum mechanical approach. It is shown that the presence of the potential barrier on the A1Π electronic state of CO leads to different formation channels for the isotopologues at low temperatures. The corresponding rate coefficients are fitted to an analytic formula.

  • 234.
    Antipov, Sergey V.
    et al.
    Department of Chemistry and Molecular Biology, University of Gothenburg.
    Gustafsson, Magnus
    Department of Chemistry, University of Gothenburg.
    Nyman, Gunnar
    Department of Chemistry and Molecular Biology, University of Gothenburg.
    Spin-orbit and rotational couplings in radiative association of C(3P) and N(4S) atoms2011In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 135, no 18, article id 184302Article in journal (Refereed)
    Abstract [en]

    The role of spin-orbit and rotational couplings in radiative association of C(3 P) and N(4 S) atoms is investigated. Couplings among doublet electronic states of the CN radical are considered, giving rise to a 6-state model of the process. The solution of the dynamical problem is based on the L2 method, where a complex absorbing potential is added to the Hamiltonian operator in order to treat continuum and bound levels in the same manner. Comparison of the energy-dependent rate coefficients calculated with and without spin-orbit and rotational couplings shows that the couplings have a strong effect on the resonance structure and low-energy baseline of the rate coefficient.

  • 235.
    Antipov, Sergey V.
    et al.
    Department of Chemistry and Molecular Biology, University of Gothenburg.
    Sjölander, Tobias
    Department of Chemistry, University of Gothenburg.
    Nyman, Gunnar
    Department of Chemistry and Molecular Biology, University of Gothenburg.
    Gustafsson, Magnus
    Department of Chemistry, University of Gothenburg.
    Rate coefficient of CN formation through radiative association: A theoretical study of quantum effects2009In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 131, no 7, article id 74302Article in journal (Refereed)
    Abstract [en]

    Radiative association of CN is simulated using a quantum dynamical as well as a semiclassical approach. A comparison of the resulting energy-resolved cross sections reveals striking quantum effects that are due to shape resonances. These, in turn, arise because of states that are quasibound by the centrifugal barrier. The quantal rate coefficient for temperatures from 40 to 1900 K has been computed using the Breit–Wigner theory to account for the resonances. Comparison with the results obtained by Singh and Andreazza [Astrophys. J.537, 261 (2000)] shows that the semiclassical method, which completely omits the shape resonances, is accurate to within 25% above room temperature. At lower temperatures the contribution from the shape resonances to the radiative association rate is more significant.

  • 236.
    Anttila, Liisa J.
    et al.
    Department of Chemistry—Ångström Laboratory, Uppsala University.
    Ghamgosar, Pedram
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Maji, Somnath
    Department of Chemistry—Ångström Laboratory, Uppsala University.
    Tian, Haining
    Department of Chemistry—Ångström Laboratory, Uppsala University.
    Ott, Sascha
    Department of Chemistry—Ångström Laboratory, Uppsala University.
    Hammarström, Leif
    Department of Chemistry—Ångström Laboratory, Uppsala University.
    Dynamics and Photochemical H-2 Evolution of Dye-NiO Photocathodes with a Biomimetic FeFe-Catalyst2016In: ACS Energy Letters, ISSN 2380-8195, Vol. 1, no 6, p. 1106-1111Article in journal (Refereed)
    Abstract [en]

    Mesoporous NiO films were cosensitized with a coumarin 343 dye and a proton reduction catalyst of the [Fe-2(CO)(6)(bdt)] (bdt = benzene-1,2-dithiolate) family. Femtosecond ultraviolet visible transient absorption experiments directly demonstrated subpicosecond hole injection into NiO from excited dyes followed by rapid (t(50%) similar to 6 ps) reduction of the catalyst on the surface with similar to 70% yield. The reduced catalyst was long-lived (2 mu s to 20 ms), which may allow protonation and a second reduction step of the catalyst to occur. A photo electrochemical device based on this photocathode produced H-2 with a Faradaic efficiency of similar to 50%. Fourier transform infrared spectroscopy and gas chromatography experiments demonstrated that the observed device deterioration with time was mainly due to catalyst degradation and desorption from the NiO surface. The insights gained from these mechanistic studies, regarding development of dye-catalyst cosensitized photocathodes, are discussed.

  • 237.
    Antzutkin, Oleg
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Norlin, N.
    Hellberg, M.
    Eriksson, P.
    Almqvist, Nils
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Leapman, R.D.
    Tycko, R.
    Petkova, A.T.
    Toth, I.
    Howes, A.P.
    Dupree, R.
    Binding of Aluminium(III)-Citrate Complexes, [Al3(H-1Cit)3(OH)]-4 and [Al3(H-1Cit)3(OH)4]-7, to Alzheimer's A-beta(1-40) Peptides: In situ Atomic Force, Electron Microscopy and Solid State 13C and 27Al NMR Studies2005In: Sixth Keele Meeting on Aluminium: Aluminium Lithosphere to Biosphere (and Back), Centro de Estudos do Ambiente e Mar, Universidade de Aveiro , 2005, p. 16-Conference paper (Other academic)
    Abstract [en]

    It is believed that Alzheimer's disease (AD) amyloid-β-peptide (Aβ) deposits contribute directly to the disease's progressive neurodegeneration. Aggregation cascade for Aβ peptides, its relevance to neurotoxicity in the course of AD, various factors modulating Aβ aggregation kinetics and experimental methods useful for these studies were recently discussed [1]. Al(III), Zn(II), Cu(II) and Fe(III) ions are often colocalized at the center of the core of Alzheimer's amyloid plaques [2] and are suggested to promote aggregation of physiological concentrations of Aβ [3]. It has also been suggested that Al can block calcium permeable putative Aβ-peptide channels in bilayer membranes [4]. Therefore studies of complexation of metal ions with Aβ-oligomers and fibrils are important in the search for the causes of and potential treatments for AD.We studied effects of highly soluble and biologically relevant aluminium(III)-citrate compounds, [Al3(H-1Cit)3(OH)]-4 and [Al3(H-1Cit)3(OH)4]-7, on the fibrillogenesis of Aβ(1-40). All resonances in 156.37 MHz 27Al and 90.52 MHz 13C MAS NMR spectra of powder Al(III)-citrate complexes were assigned. 27Al MAS NMR of dialysed samples of Aβ(1-40) co-incubated with the Al(III)-citrate complexes at different concentrations in TRIS buffer solutions, pH 7.4, shows that Al(III)-citrates bind to Aβ(1-40) as [Al3(H-1Cit)3(OH)]-4 and either accelerate ([Al3(H-1Cit)3(OH)]-4 complex) or retard ([Al3(H-1Cit)3(OH)4]-7 compound) aggregation of Aβ(1-40) as revealed by AFM. [1] ON Antzutkin, Magn. Reson. Chem. 42 (2004) 231; [2] MA Lovell et al., J. Neurol. Sci. 158 (1998) 47; Ch Exley et al., Al and Alzheimer's disease, Ch Exley (Ed)1998) 47; Ch Exley , Ch Exley (Ed) Elsevier Science, 2001, 421; [3] PW Mantyh et al., J. Neurochem. 61 (1993) 1171; [4] N Arispe et al, PNAS 90 (1993) 567.

  • 238.
    Anzellini, S.
    et al.
    Diamond Light Source Ltd., Diamond House, Harwell Science Campus, Didcot, Oxfordshire, United Kingdom.
    Errandonea, D.
    Departamento de Física Aplicada-Instituto de Ciencia de Materiales, Matter at High Pressure (MALTA) Consolider Team, Universidad de Valencia, Edificio de Investigación, Valencia, Spain.
    MacLeod, S. G.
    AWE, Aldermaston, Reading, United Kingdom. SUPA, School of Physics and Astronomy, and Centre for Science at Extreme Conditions,The University of Edinburgh, Edinburgh, United Kingdom.
    Botella, Pablo
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Daisenberger, D.
    Diamond Light Source Ltd., Diamond House, Harwell Science Campus, Didcot, Oxfordshire, United Kingdom.
    De’Ath, M.
    AWE, Aldermaston, Reading, United Kingdom.
    Gonzalez-Platas, J.
    Departmento de Física, Universidad de La Laguna, Avda. Astrofísico Fco. Sánchez s/n, Tenerife, Spain.
    Ibáñez, J.
    Institute of Earth Sciences Jaume Almera, CSIC, Barcelona, Spain.
    McMahon, M. I.
    SUPA, School of Physics and Astronomy, and Centre for Science at Extreme Conditions,The University of Edinburgh, Edinburgh, United Kingdom.
    Munro, K. A.
    SUPA, School of Physics and Astronomy, and Centre for Science at Extreme Conditions,The University of Edinburgh, Edinburgh, United Kingdom.
    Popescu, C.
    CELLS-ALBA Synchrotron Light Facility, Barcelona, Spain.
    Ruiz-Fuertes, J.
    DCITIMAC, MALTA Consolider Team, Universidad de Cantabria, Santander, Spain.
    Wilson, C. W.
    AWE, Aldermaston, Reading, United Kingdom.
    Phase diagram of calcium at high pressure and high temperature2018In: Physical review materials, ISSN 2475-9953, Vol. 2, no 8, article id 083608Article in journal (Refereed)
    Abstract [en]

    Resistively heated diamond-anvil cells have been used together with synchrotron x-ray diffraction to investigate the phase diagram of calcium up to 50 GPa and 800 K. The phase boundaries between the Ca-I (fcc), Ca-II (bcc), and Ca-III (simple cubic, sc) phases have been determined at these pressure-temperature conditions, and the ambient temperature equation of state has been generated. The equation of state parameters at ambient temperature have been determined from the experimental compression curve of the observed phases by using third-order Birch-Murnaghan and Vinet equations. A thermal equation of state was also determined for Ca-I and Ca-II by combining the room-temperature Birch-Murnaghan equation of state with a Berman-type thermal expansion model.

  • 239.
    Apazidis, Nicholas
    KTH, School of Engineering Sciences (SCI), Mechanics.
    Numerical investigation of shock induced bubble collapse in water2016In: Physics of fluids, ISSN 1070-6631, E-ISSN 1089-7666, Vol. 28, no 4, article id 046101Article in journal (Refereed)
    Abstract [en]

    A semi-conservative, stable, interphase-capturing numerical scheme for shock propagation in heterogeneous systems is applied to the problem of shock propagation in liquid-gas systems. The scheme is based on the volume-fraction formulation of the equations of motion for liquid and gas phases with separate equations of state. The semi-conservative formulation of the governing equations ensures the absence of spurious pressure oscillations at the material interphases between liquid and gas. Interaction of a planar shock in water with a single spherical bubble as well as twin adjacent bubbles is investigated. Several stages of the interaction process are considered, including focusing of the transmitted shock within the deformed bubble, creation of a water-hammer shock as well as generation of high-speed liquid jet in the later stages of the process.

  • 240. Aperia, Anita Chatarina
    et al.
    Akkuratov, Evgeny E
    Fontana, Jacopo Maria
    KTH, School of Engineering Sciences (SCI), Applied Physics, Cell Physics.
    Brismar, Hjalmar
    KTH, School of Engineering Sciences (SCI), Applied Physics, Cell Physics.
    Na+, K+-ATPase, a new class of plasma membrane receptors2016In: American Journal of Physiology - Cell Physiology, ISSN 0363-6143, E-ISSN 1522-1563, Vol. 310, no 7, p. C491-C495Article in journal (Refereed)
    Abstract [en]

    The Na(+), K(+)-ATPase (NKA) differs from most other ion transporters not only in its capacity to maintain a steep electrochemical gradient across the plasma membrane but also as a receptor for a family of cardiotonic steroids, to which ouabain belongs. Studies from many groups, performed during the last fifteen years, have demonstrated that ouabain, a member of the cardiotonic steroid family, can activate a network of signaling molecules and that NKA will also serve as a signal transducer that can provide a feed back loop between NKA and the mitochondria. This brief review summarizes the current knowledge and controversies with regard to the understanding of NKA signaling.

  • 241. Apostolakis, A
    et al.
    Aslanides, E.
    -.
    Backenstoss, G.
    -.
    Bargassa, P.
    -.
    Behnke, O.
    -.
    Benelli, A.
    -.
    Bertin, V.
    -.
    Blanc, F.
    -.
    Bloch, P.
    -.
    Carlson, P.
    KTH, School of Engineering Sciences (SCI).
    Danielsson, Mats
    KTH, Superseded Departments, Physics.
    A determination of the CP violation parameter η+- from the decay of strangeness-tagged neutral kaons1999In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 458, no 4, p. 545-552Article in journal (Refereed)
    Abstract [en]

    LEAR offered unique opportunities to study the symmetries which exist between matter and antimatter. At variance with other approaches at this facility, CPLEAR was an experiment devoted to the study of CP, T and CPT symmetries in the neutral-kaon system. A variety of measurements allowed us to determine with high precision the parameters which describe the time evolution of the neutral kaons and their antiparticles, including decay amplitudes, and the related symmetry properties. Limits concerning quantum-mechanical predictions (EPR, coherence of the wave function) or the equivalence principle of general relativity have been obtained. An account of the main features of the experiment and its performances is given here, together with the results achieved.

  • 242.
    Appelgren, Patrik
    et al.
    KTH, School of Electrical Engineering (EES), Space and Plasma Physics. Swedish Defence Research Agency (FOI), Sweden.
    Hurtig, T.
    Larsson, A.
    Skoglund, M.
    Parametric studies of an electrohydrodynamic plasma actuator for boundary layer flow control2009In: PPC '09. IEEE Pulsed Power Conference, 2009, IEEE , 2009, p. 1069-1074Conference paper (Refereed)
    Abstract [en]

    An electrohydrodynamic plasma actuator can be used as an aerodynamic flow control device. A plasma actuator is realised as a surface-mounted dielectric barrier discharge (DBD) that transfers directed energy from ions in the discharge to the surrounding air. Parametric studies have been performed in order to investigate the relative efficiency in terms of electrical power into the actuator versus mechanical power in the generated boundary flow. The parametric study includes variations of the applied driving voltage and frequency as well as different electrode and dielectric materials. It is found that, within the range tested, for each value of electrical power into the actuator there exists an optimum driving frequency in terms of boundary layer flow velocity. It is also found that the same trend seems to be true when analyzing electric to mechanical efficiency of the device, i.e. for a given input power there exists an optimum driving frequency that produces the highest efficiency. However, this peak in efficiency of the actuator lies on the edge of the parametric space tested so that further experiments are needed to validate these results.

  • 243.
    Appelquist, Ellinor
    et al.
    KTH, School of Engineering Sciences (SCI), Mechanics, Fluid Physics.
    Imayama, Shintaro
    KTH, School of Engineering Sciences (SCI), Mechanics, Fluid Physics.
    Alfredsson, Henrik
    KTH, School of Engineering Sciences (SCI), Mechanics, Fluid Physics.
    Schlatter, Philipp
    KTH, School of Engineering Sciences (SCI), Mechanics, Stability, Transition and Control.
    Lingwood, Rebecca
    KTH, School of Engineering Sciences (SCI), Mechanics, Fluid Physics. University of Cambridge, UK.
    Linear disturbances in the rotating-disk flow: a comparison between results from simulations, experiments and theory2014Report (Other academic)
  • 244.
    Arabi Ardehali, Arash
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Physics. Inst Res Fundamental Sci IPM, Sch Phys, POB 19395-5531, Tehran, Iran.
    Cardy-like asymptotics of the 4d N=4 index and AdS(5) blackholes2019In: Journal of High Energy Physics (JHEP), ISSN 1126-6708, E-ISSN 1029-8479, no 6, article id 134Article in journal (Refereed)
    Abstract [en]

    Choi, Kim, Kim, and Nahmgoong have recently pioneered analyzing a Cardy-like limit of the superconformal index of the 4d N=4 theory with complexified fugacities which encodes the entropy of the dual supersymmetric AdS(5) blackholes. Here we study the Cardy-like asymptotics of the index within the rigorous framework of elliptic hypergeometric integrals, thereby filling a gap in their derivation of the blackhole entropy function, finding a new blackhole saddle-point, and demonstrating novel bifurcation phenomena in the asymptotics of the index as a function of fugacity phases. We also comment on the relevance of the supersymmetric Casimir energy to the blackhole entropy function in the present context.

  • 245.
    Ardenfors, Oscar
    Stockholm University, Faculty of Science, Department of Physics.
    Out-of-field doses from proton therapy and doses from CBCT imaging: Risk of radiation-induced second cancer from modern radiotherapy2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The use of ionizing radiation for treatment of cancer diseases is continuously increasing as patient survival is improving and new treatment techniques are emerging. While this development is beneficial for curing primary tumors, concerns have been raised regarding the unwanted dose contribution to healthy tissues of patients and the associated risk of radiation-induced second cancer (RISC). This is especially important for younger patients receiving radiotherapy more often than before and for whom the risk of developing RISC is elevated in comparison to the typical adult radiotherapy patient. In order to estimate the risk of RISC associated with modern radiotherapy and imaging, the associated radiation doses must be determined.

    Patients undergoing radiotherapy receive in-field doses from the primary beam but also out-of-field doses originating from secondary radiation produced in the beamline and within the patient. Over the last years, the use of proton pencil beam scanning (PBS) therapy has rapidly increased due to its potential to reduce the in-field doses to healthy tissues in comparison to photon therapy. One of the drawbacks with proton therapy is the production of neutrons capable of travelling large distances and depositing out-of-field doses to organs located far from the primary treatment field. The dose reduction associated with proton PBS therapy could consequently be affected by the out-of-field doses originating from secondary radiation.

    The sharp dose gradients associated with modern treatment techniques, such as photon intensity-modulated radiotherapy (IMRT) and proton PBS therapy require more frequent and accurate patient imaging in comparison to conventional treatment techniques such as three-dimensional conformal radiotherapy (CRT). Setup verification images could be acquired with cone-beam computed tomography (CBCT) producing three-dimensional patient images at the cost of an increased patient dose in comparison to planar x-ray imaging. Concerns have been raised regarding the cumulative patient doses from repeated CBCT imaging versus the dose-saving benefits associated with modern radiotherapy techniques like IMRT and proton PBS.

    In this thesis, a study on the in-field and out-of-field doses to healthy tissues from photon IMRT and CRT treatments of head and neck tumors showed that the risk of RISC was unaffected by the employed treatment technique and indicated that the lifetime risk of cancer induction was of the order of 1-2%.

    Results from measurements and Monte Carlo simulations showed that the out-of-field absorbed doses and equivalent doses associated with proton PBS treatments of brain tumors were up to 60 µGy/Gy and 150 µSv/Gy, respectively. The risk of RISC associated with these out-of-field doses was in the range of approximately one induced cancer in ten thousand treated patients. A simulation study on the doses from a proton gantry-mounted CBCT system showed that repeated CBCT imaging could result in cumulative organ doses of almost 2 Gy. The conclusion from these studies is that the dose-sparing effects of proton PBS therapy are not overshadowed by the out-of-field doses originating from secondary radiation for brain tumor treatments, but that the cumulative doses from repeated CBCT imaging could have a relevant impact on the overall dose reduction.

  • 246.
    Ardenfors, Oscar
    Stockholm University, Faculty of Science, Department of Physics.
    Secondary doses to healthy tissues from radiotherapy and modern imaging techniques2017Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    The use of ionizing radiation for treatment of cancer diseases is continuously increasing giving rise to several new questions and concerns. One of the most important aspects of this is the associated dose imparted to healthy tissues. This unwanted dose contribution is a result of both radiotherapy procedures and diagnostic imaging. The dose deposition in healthy tissues from external radiotherapy mainly originates from the incident primary beam. However, the patient also receives non-negligible organ doses originating from secondary radiation produced in the treatment machine and within the patient. This secondary radiation, especially neutrons, can travel large distances and consequently deposit doses to organs located far from the primary treatment field. The dose contribution to healthy organs from diagnostic procedures is growing due to the increase in repeated imaging performed in conjunction with radiotherapy. Also, patients undergoing both external radiotherapy and radionuclide therapy with radioactive isotopes could receive a high combined dose burden to healthy tissues.

    The need to quantify the secondary dose contribution and the associated risk of radiation-induced cancer is a relevant matter as new techniques are continuously emerging both in the field of radiotherapy and imaging. The technical advances in modern treatment techniques such as intensity modulated radiotherapy, rotational therapy and ion therapy have contributed to the overall increase in patient survival. A parallel development in medical imaging has caused an increase in the use of cone-beam computed tomography for repeated image-guidance imaging providing better tumor localization and a reduction in high doses deposited in adjacent healthy tissues.

    The most accurate way of estimating the risk of radiation-induced secondary cancers is to conduct comprehensive epidemiological studies on an exposed population stretching over several decades. This has been done in the past using cohorts of survivors of the atomic bombings and other nuclear accidents and medical exposures. However, the implementation of these epidemiological data is complex as the types of exposure differ greatly from modern radiotherapy procedures. Also, the long latency associated with radiation-induced secondary cancers further complicate the use of epidemiological data.

    Thus, the goal of achieving a dose-response relationship for secondary cancers is not only a matter of assessing the dose to the patient but also on how this data should be analyzed. Today, the most popular way of achieving this is through theoretical risk models using patient-specific parameters including dose distributions and risk coefficients obtained for populations from epidemiological studies.

    Due to the difficulties associated with performing measurements of radiation-induced organ doses from treatment and imaging, the dose is often calculated either analytically using an algorithm employed in the clinical treatment planning system or through Monte Carlo simulations that offer the most accurate tool for such calculations. To allow for accurate Monte Carlo simulations of secondary radiation from external radiotherapy the beam model should be validated against measurements with regard to both the primary beam and the out-of-field secondary radiation.

    These aspects have been investigated in individual studies that make the object of the articles included in this thesis. Paper I presents a literature review of secondary doses from different treatment and imaging modalities. Paper II shows a comparison between the risks of radiation-induced cancer for patients treated for head and neck cancer using two different treatment techniques. Paper III deals with Monte Carlo simulations of doses to healthy tissues from radionuclide therapy given in conjunction with external radiotherapy. Paper IV presents the validation of a proton spot scanning Monte Carlo model.

  • 247.
    Ardenfors, Oscar
    et al.
    Stockholm University, Faculty of Science, Department of Physics.
    Dasu, Alexandru
    Kopeć, Mariusz
    Gudowska, Irena
    Stockholm University, Faculty of Science, Department of Physics.
    Modelling of a proton spot scanning system using MCNP62017In: Journal of Physics, Conference Series, ISSN 1742-6588, E-ISSN 1742-6596, Vol. 860, article id 012025Article in journal (Refereed)
    Abstract [en]

    The aim of this work was to model the characteristics of a clinical proton spot scanning beam using Monte Carlo simulations with the code MCNP6. The proton beam was defined using parameters obtained from beam commissioning at the Skandion Clinic, Uppsala, Sweden. Simulations were evaluated against measurements for proton energies between 60 and 226 MeV with regard to range in water, lateral spot sizes in air and absorbed dose depth profiles in water. The model was also used to evaluate the experimental impact of lateral signal losses in an ionization chamber through simulations using different detector radii. Simulated and measured distal ranges agreed within 0.1 mm for R90 and R80 , and within 0.2 mm for R50 . The average absolute difference of all spot sizes was 0.1 mm. The average agreement of absorbed dose integrals and Bragg-peak heights was 0.9%. Lateral signal losses increased with incident proton energy with a maximum signal loss of 7% for 226 MeV protons. The good agreement between simulations and measurements supports the assumptions and parameters employed in the presented Monte Carlo model. The characteristics of the proton spot scanning beam were accurately reproduced and the model will prove useful in future studies on secondary neutrons.

  • 248.
    Aref’eva, I. Ya.
    et al.
    Russian Academy of Sciences, Russia.
    Djordjevic, G. S.
    University of Niš, Serbia.
    Khrennikov, Andrei
    Linnaeus University, Faculty of Technology, Department of Mathematics.
    Kozyrev, S. V.
    Russian Academy of Sciences, Russia.
    Rakic, Z.
    University of Belgrade, Serbia.
    Volovich, I. V.
    Russian Academy of Sciences, Russia.
    p-Adic mathematical physics and B. Dragovich research2017In: P-Adic Numbers, Ultrametric Analysis, and Applications, ISSN 2070-0466, E-ISSN 2070-0474, Vol. 9, no 1, p. 82-85Article in journal (Refereed)
    Abstract [en]

    We present a brief review of some parts of p-adic mathematical physics related to the scientific work of Branko Dragovich on the occasion of his 70th birthday.

  • 249.
    Armakavicius, Nerijus
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Study of novel electronic materials by mid-infrared and terahertz optical Hall effect2017Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Development of silicon based electronics have revolutionized our every day life during the last three decades. Nowadays Si based devices operate close to their theoretical limits that is becoming a bottleneck for further progress. In particular, for the growing field of high frequency and high power electronics, Si cannot offer the required properties. Development of materials capable of providing high current densities, carrier mobilities and high breakdown fields is crucial for a progress in state of the art electronics.

    Epitaxial graphene grown on semi-insulating silicon carbide substrates has a high potential to be integrated in the current planar device technologies. High electron mobilities and sheet carrier densities make graphene extremely attractive for high frequency analog applications. One of the remaining challenges is the interaction of epitaxial graphene with the substrate. Typically, much lower free charge carrier mobilities, compared to free standing graphene, and doping, due to charge transfer from the substrate, is reported. Thus, a good understanding of the intrinsic free charge carriers properties and the factors affecting them is very important for further development of epitaxial graphene.

    III-group nitrides have been extensively studied and already have proven their high efficiency as light sources for short wavelengths. High carrier mobilities and breakdown electric fields were demonstrated for III-group nitrides, making them attractive for high frequency and high power applications. Currently, In-rich InGaN alloys and AlGaN/GaN high electron mobility structures are of high interest for the research community due to open fundamental questions.

    Electrical characterization techniques, commonly used for the determination of free charge carrier properties, require good ohmic and Schottky contacts, which in certain cases can be difficult to achieve. Access to electrical properties of buried conductive channels in multilayered structures requires modification of samples and good knowledge of the electrical properties of all electrical contact within the structure. Moreover, the use of electrical contacts to electrically characterize two-dimensional electronic materials, such as graphene, can alter their intrinsic properties. Furthermore, the determination of effective mass parameters commonly employs cyclotron resonance and Shubnikov-de Haas oscillations measurements, which require long scattering times of free charge carriers, high magnetic fields and low temperatures.

    The optical Hall effect is an external magnetic field induced optical anisotropy in  conductive layers due to the motion of the free charge carriers under the influence of the Lorentz force, and is equivalent to the electrical Hall effect at optical frequencies. The optical Hall effect can be measured by generalized ellipsometry and provides a powerful method for the determination of free charge carrier properties in a non-destructive and contactless manner. In principle, a single optical Hall effect measurement can provide quantitative information about free charge carrier types, concentrations, mobilities and effective mass parameters at temperatures ranging from few kelvins to room temperature and above. Further, it was demonstrated that for transparent samples, a backside cavity can be employed to enhance the optical Hall effect.

    Measurement of the optical Hall effect by generalized ellipsometry is an indirect technique requiring subsequent data analysis. Parameterized optical models are fitted to match experimentally measured ellipsometric data by varying physically significant parameters. Analysis of the optical response of samples, containing free charge carriers, employing optical models based on the classical Drude model, which is augmented with an external magnetic field contribution, provide access to the free charge carrier properties.

    The main research results of the graduate studies presented in this licentiate thesis are summarized in the five scientific papers.

    Paper I. Description of the custom-built terahertz frequency-domain spectroscopic ellipsometer at Linköping University. The terahertz ellipsometer capabilities are demonstrated by an accurate determination of the isotropic and anisotropic refractive indices of silicon and m-plane sapphire, respectively. Further, terahertz optical Hall effect measurements of an AlGaN/GaN high electron mobility structures were employed to extract the two-dimensional electron gas sheet density, mobility and effective mass parameters. Last, in-situ optical Hall effect measurement on epitaxial graphene in a gas cell with controllable environment, were used to study the effects of environmental doping on the mobility and carrier concentration.

    Paper II. Presents terahertz cavity-enhanced optical Hall measurements of the monolayer and multilayer epitaxial graphene on semi-insulating 4H-SiC (0001) substrates. The data analysis revealed p-type doping for monolayer graphene with a carrier density in the low 1012 cm−2 range and a carrier mobility of 1550 cm2/V·s. For the multilayer epitaxial graphene, n-type doping with a carrier density in the low 1013 cm−2 range, a mobility of 470 cm2/V·s and an effective mass of (0.14 ± 0.03) m0 were extracted. The measurements demonstrate that cavity-enhanced optical Hall effect measurements can be applied to study electronic properties of two-dimensional materials.

    Paper III. Terahertz cavity-enhanced optical Hall effect measurements are employed to study anisotropic transport in as-grown monolayer, quasi free-standing monolayer and quasi free-standing bilayer epitaxial graphene on semi-insulating 4H-SiC (0001) substrates. The data analysis revealed a strong anisotropy in the carrier mobilities of the quasi freestanding bilayer graphene. The anisotropy is demonstrated to be induced by carriers scattering at the step edges of the SiC, by showing that the mobility is higher along the step than across them. The scattering mechanism is discussed based on the results of the optical Hall effect, low-energy electron microscopy, low-energy electron diffraction and Raman measurements.

    Paper IV. Mid-infrared spectroscopic ellipsometry and mid-infrared optical Hall effect measurements are employed to determine the electron effective mass in an In0.33Ga0.67N epitaxial layer. The data analysis reveals slightly anisotropic effective mass and carrier mobility parameters together with the optical phonon frequencies and broadenings.

    Paper V. Terahertz cavity-enhanced optical Hall measurements are employed to study the free charge carrier properties in a set of AlGaN/GaN high electron mobility structures with modified interfaces. The results show that the interface structure has a significant effect on the free charge carrier mobility and that the sample with a sharp interface between an AlGaN barrier and a GaN buffer layers exhibits a record mobility of 2332±73 cm2/V·s. The determined effective mass parameters showed an increase compared to the GaN value, that is attributed the the penetration of the electron wavefunction into the AlGaN barrier layer.

  • 250. Armougom, J.
    et al.
    Melkonian, J. -M
    Raybaut, M.
    Dherbecourt, J. -B
    Gorju, G.
    Godard, A.
    Cotzee, Riaan
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Pasiskevicius, Valdas
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Kadlcak, J.
    Longwave Infrared Lidar Based on Parametric Sources for Standoff Detection of Gaseous Chemicals2018In: 2018 Conference on Lasers and Electro-Optics, CLEO 2018 - Proceedings, Institute of Electrical and Electronics Engineers (IEEE), 2018, article id 8426308Conference paper (Refereed)
    Abstract [en]

    We report on a longwave infrared lidar, tailored for detection of chemical warfare agents in the gaseous phase. The emitter is based on single-frequency 2 μm parametric oscillator/amplifier systems followed by a ZnGeP2 downconversion stage.

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