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  • 1.
    A. Strumpfer, Johan
    et al.
    University of Illinois at Urbana Champaign, Urbana, IL, USA; Beckman Institute, Urbana, IL, USA.
    von Castelmur, Eleonore
    Institute of Integrative Biology, University of Liverpool, Liverpool, IL, USA.
    Franke, Barbara
    Institute of Integrative Biology, University of Liverpool, Liverpool, United Kingdom.
    Barbieri, Sonia
    Institute of Integrative Biology, University of Liverpool, Liverpool, United Kingdom.
    Bogomolovas, Julijus
    Universitätsmedizin Mannheim, Mannheim, Germany.
    Qadota, Hiroshi
    Department of Pathology, Emory University, Atlanta, GA, USA.
    Konarv, Petr
    European Molecular Biology Laboratory, Hamburg, Germany.
    Svergun, Dmitri
    European Molecular Biology Laboratory, Hamburg, Germany.
    Labeit, Siegfried
    Department for Integrative Pathophysiology, Universitätsmedizin Mannheim, Mannheim, Germany.
    Schulten, Klaus
    University of Illinois at Urbana Champaign, Urbana, IL, USA Beckman Institute, Urbana, IL, USA.
    Benian, Guy
    Department of Pathology, Emory University, Atlanta, GA, USA.
    Mayans, Olga
    Institute of Integrative Biology, University of Liverpool, Liverpool, United Kingdom.
    Stretching of Twitchin Kinase2012Ingår i: Biophysical Journal, ISSN 0006-3495, E-ISSN 1542-0086, Vol. 102, nr 3 Supplement 1, s. 361a-362aArtikel i tidskrift (Refereegranskat)
    Abstract [en]

    The giant proteins from the titin family, that form cytoskeletal filaments, have emerged as key mechanotransducers in the sarcomere. These proteins contain a conserved kinase region, which is auto-inhibited by a C-terminal tail domain. The inhibitory tail domain occludes the active sites of the kinases, thus preventing ATP from binding. It was proposed that through application of a force, such as that arising during muscle contraction, the inhibitory tail becomes detached, lifting inhibition. The force-sensing ability of titin kinase was demonstrated in AFM experiments and simulations [Puchner, et al., 2008, PNAS:105, 13385], which showed indeed that mechanical forces can remove the autoinhibitory tail of titin kinase. We report here steered molecular dynamics simulations (SMD) of the very recently resolved crystal structure of twitchin kinase, containing the kinase region and flanking fibronectin and immuniglobulin domains, that show a variant mechanism. Despite the significant structural and sequence similarity to titin kinase, the autoinhibitory tail of twitchin kinase remains in place upon stretching, while the N-terminal lobe of the kinase unfolds. The SMD simulations also show that the detachment and stretching of the linker between fibronectin and kinase regions, and the partial extension of the autoinhibitory tail, are the primary force-response. We postulate that this stretched state, where all structural elements are still intact, may represent the physiologically active state.

  • 2.
    Aakumiah, Prince Osei
    Linköpings universitet, Institutionen för tema, Tema vatten i natur och samhälle.
    Water Management and Health in Ghana: Caes Study - Kumasi2007Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats
    Abstract [en]

    There have been multiple cases of drinking water related diseases in Ghana, particularly the cities. Kumasi, the second largest city is recording high figures of drinking water related diseases. The Ghana water and sewage company is supposed to provide adequate safe drinking water to the people. However, the company has failed to provide this service effectively. Various reasons have been given by the company on its inability to perform efficiently. Meanwhile the government decided lately to privatise water in the cities to facilitate access to quality water through what is called “FULL COST RECOVERY”. This attracted a lot of international companies to Ghana but this has also generated protest and demonstrations. The argument is that these foreign companies are basically profit oriented and considering the fact that most of the affected people are very poor, suggesting they cannot afford it.

    The study is aimed at finding out the relationship between water management and health in the study area and how effective water management through full community participation could help provide adequate safe drinking water. The study was a non-interventional descriptive type using both qualitative and quantitative methods. It was conducted in Kumasi, the second largest city in Ghana. A total of 100 residents from the communities was selected through systematic sampling and interviewed. This includes 86 local residents and 14 key informer interviews. The study also relied on observation as well as some selected literature.

    The results confirmed that drinking water related diseases is on the increase with the most affected people being the poor living in shanty and informal areas of the city. It was also found that most people in the city are willing to render any services to provide safe drinking water. But in relative terms, most of these people are very poor with high percentage of illiterates and may only contribute if there is a good relation and trust among all. It however appears that community participation is a good option for the city provided that stakeholders are made to play effective roles.

  • 3.
    Aalberg, Laura
    et al.
    National Bureau of Investigation, P.O. Box 285, FIN-01301 Vantaa, Finland.
    Andersson, Kjell
    Swedish National Laboratory of Forensic Science, SKL, SE-581 94 Linköping, Sweden.
    Bertler, Christina
    Swedish National Laboratory of Forensic Science, SKL, SE-581 94 Linköping, Sweden.
    Borén, Hans
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Organisk Analytisk Kemi.
    Cole, Michael D.
    Forensic Science Unit, University of Strathclyde, 204 George Street, Glasgow, UK.
    Dahlén, Johan
    Swedish National Laboratory of Forensic Science, SKL, SE-581 94 Linköping, Sweden.
    Finnon, Yvonne
    Forensic Science Unit, University of Strathclyde, 204 George Street, Glasgow, UK.
    Huizer, Henk
    Netherlands Forensic Institute, Volmerlaan 17, 2288 GD Rijswijk, The Netherlands.
    Jalava, Kajsa
    National Bureau of Investigation, P.O. Box 285, FIN-01301 Vantaa, Finland.
    Kaa, Elisabet
    Department of Forensic Medicine, University of Aarhus, Skovagervej 2, DK-8240 Risskov, Denmark.
    Lock, Eric
    Netherlands Forensic Institute, Volmerlaan 17, 2288 GD Rijswijk, The Netherlands/Institut de Police Scientifique, University of Lausanne, Batiment de Chimie, CH-1015 Lausanne-Dorigny, Switzerland.
    Lopes, Alvaro
    Laboratorio de Policia Cientifica, Policia Judiciaria, Rua Gomes Freire 174, 1169-007 Lisbon, Portugal.
    Poortman-van-der Meer, Anneke
    Department of Forensic Medicine, University of Aarhus, Skovagervej 2, DK-8240 Risskov, Denmark.
    Sippola, Erkki
    National Bureau of Investigation, P.O. Box 285, FIN-01301 Vantaa, Finland.
    Development of a harmonised method for the profiling of amphetamines: I. Synthesis of standards and compilation of analytical data2005Ingår i: Forensic Science International, ISSN 0379-0738, E-ISSN 1872-6283, Vol. 149, nr 2-3, s. 219-229Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Reference material was synthesised for 21 substances that are frequently present as synthetic impurities, i.e. by-products, in illicitly produced amphetamine. Each of these substances is a typical by-product for at least one of the three approaches most often used to synthesise amphetamine, namely, the Leuckart, the reductive amination of benzyl methyl ketone, and the nitrostyrene routes. A large body of data on the substances was recorded, including the following: mass spectra, ultraviolet spectra, Fourier transform infrared spectra, infrared spectra in gas phase, and 1H NMR and 13C NMR spectra. © 2004 Elsevier Ireland Ltd. All rights reserved.

  • 4. Aavikko, R.
    et al.
    Saarinen, K.
    Magnusson, Björn
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial.
    Janzén, Erik
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial.
    Clustering of Vacancies in Semi-Insulating SiC Observed with Positron Spectroscopy2006Ingår i: Materials Science Forum, Vols. 527-529, 2006, Vol. 527-529, s. 575-578Konferensbidrag (Refereegranskat)
  • 5. Aavikko, R.
    et al.
    Saarinen, K.
    Tuomisto, F.
    Magnusson, Björn
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Nguyen, Son Tien
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Janzén, Erik
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Clustering of vacancy defects in high-purity semi-insulating SiC2007Ingår i: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 75, nr 8, s. 085208-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Positron lifetime spectroscopy was used to study native vacancy defects in semi-insulating silicon carbide. The material is shown to contain (i) vacancy clusters consisting of four to five missing atoms and (ii) Si-vacancy-related negatively charged defects. The total open volume bound to the clusters anticorrelates with the electrical resistivity in both as-grown and annealed materials. Our results suggest that Si-vacancy-related complexes electrically compensate the as-grown material, but migrate to increase the size of the clusters during annealing, leading to loss of resistivity. © 2007 The American Physical Society.

  • 6.
    Abadias, Gregory
    et al.
    University of Poitiers, France.
    Sarakinos, Kostas
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Plasma och beläggningsfysik. Linköpings universitet, Tekniska högskolan.
    Fenker, Martin
    FEM, Germany.
    Kassavetis, Spiros
    Aristotle University of Thessaloniki, Greece.
    Editorial Material: Preface in SURFACE and COATINGS TECHNOLOGY, vol 255, issue , pp2014Ingår i: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 255Artikel i tidskrift (Övrigt vetenskapligt)
    Abstract [en]

    n/a

  • 7.
    Abadir Guirgis, Georg
    Linköpings universitet, Institutionen för datavetenskap.
    Lärarperspektiv på riskutbildningen för motorcyklister2011Självständigt arbete på grundnivå (kandidatexamen), 12 poäng / 18 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Under det senaste decenniet har det i Sverige blivit allt populärare att åka motorcykel. Enobligatorisk riskutbildning för behörighet A och A1 infördes från och med den 1 november2009. Då riskutbildningen är ny har få utvärderingar gjorts.Denna studie utvärderar riskutbildningen för motorcyklister utifrån trafikskolläraresperspektiv. Målet har varit att sammanställa synpunkter och erfarenheter från lärarna påutbildningen. Ett ytterligare mål har varit att undersöka trafikskollärarnas upplevda effekter avutbildningen på elevers trafikbeteende. Sex semistrukturerade intervjuer med trafikskolläraresamt en observationsstudie på olika trafikskolor genomfördes. Utöver detta genomfördesdeltagande observation av en fortbildning där 15 trafikskollärare deltog. Resultatet frånstudien visar att lärarna anser att behovet av riskutbildningen är stort och attimplementationen av den nya riskutbildningen gått bra. Förutom att elever efter utbildningenrefererar till den, vilket enligt lärarna indikerar att de tagit till sig vad som sagts, märks det nui större utsträckning än tidigare att elever kör lugnare och tänker sig mer för i vissasituationer. Detta påtalades vara ett klart önskvärt resultat.

  • 8.
    Abadir Guirgis, Georg
    Linköpings universitet, Institutionen för datavetenskap. Linköpings universitet, Filosofiska fakulteten.
    Mindre energi och rätt tid: Utvärdering av utbildning och träning för lokförare i energieffektiv körning – en simulatorstudie2013Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Under 1980-talet introducerades den första tågsimulatorn i svensk lokförarutbildning. Denna simulator är fortfarande den enda fullskalesimulator som används för att utbilda lokförare i Sverige. En anledning till att det inte finns fler tycks vara att det bl.a. saknas pedagogiska och ekonomiska motiv för en utvidgad användning av simulatorer i undervisning och träning. Energibesparingar inom spårtrafik dvs. att köra tåg energieffektivt är idag mycket aktuellt hos alla tågoperatörer i Sverige. Vissa operatörer utbildar redan sina förare teoretiskt i energieffektiv körning och tester av energieffektiv körning i verklig trafik har visat på en möjlig besparing om 16 % energi efter det att lokförare genomgått en teoretisk utbildning i energieffektiv körning. Då det emellertid fanns en del osäkerhet i mätdata från de tester som genomförts i verklig trafik och betingelserna samt försöksprocedur varierade mellan förarna fanns det ett behov av att undersöka besparingspotentialen under mer kontrollerade former. Dessutom visade sig att utbildning samt tillgång till ett stödsystem under körning gav en mindre besparing i energi (13 %). Således genomfördes en studie med hjälp av en tågsimulator. I simulatorn har man full kontroll på mätdata och betingelserna är lika för alla förare. Simulatorn som användes i studien är utvecklad på VTI (Statens väg- och transportforskningsinstitut) och är modellerad efter en X50 Regina. Syftet med denna studie var således att undersöka om samma teoretiska utbildning i energieffektiv körning, i kombination med simulatorträning under ideala förhållanden skulle ge lika bra eller bättre energibesparing jämfört med resultaten från tester i verklig trafik. Vidare undersöktes effekten av återkoppling under träningen med avseende på energibesparing. I studien deltog 24 lokförarelever som delades in i tre grupper med 8 elever i varje. Två av grupperna fick genomföra två körningar (referens- och testkörning) med utbildning och simulatorträning mellan tillfällena, medan den tredje gruppen (kontrollgrupp) endast genomförde referens- och testkörning utan utbildning och träning. De två grupperna som fick utbildning fick dock träna under två olika betingelser, en med återkoppling (energiförbrukning och banlutning) och en utan återkoppling. Det visade sig att utbildning i energieffektiv körning i kombination med 30 minuters simulatorträning resulterade i en total besparing för båda grupperna på ungefär 24 % energi, om man sen tar hänsyn till att man förbättrar sin körning genom att bara få tillfälle att köra upprepade gånger (kontrollgruppen använde 8 % mindre energi andra gången) så visade det sig att besparingen blev lika stor som den man fann i verklig trafik (16 %). Då resultaten blev lika fast betingelserna var olika finns det anledning till att vidare undersöka hur olika körförhållanden påverkar utfallet. Dessutom behöver man bättre förstå varför utbildning plus stödsystem gav mindre effekt än bara utbildning i verklig trafik samt varför återkoppling under träning inte gav någon påvisbar effekt. Det vill säga det finns anledning till ytterligare insatser för att utforma träning och stödsystem till förarna. Förutom energibesparing visade resultatet att rättidigheten förbättrades efter utbildning och simulatorträning. Resultaten talar för att det finns outnyttjad potential för tågsimulatorer i den svenska lokförarutbildningen både för att träna och utvärdera effekter av utbildningsinsatser.

  • 9.
    Abbas, Muhammad Hassan
    et al.
    Linköpings universitet, Institutionen för datavetenskap.
    Khan, Mati-ur-Rehman
    Linköpings universitet, Institutionen för datavetenskap.
    Correlational Analysis of Drivers Personality Traits and Styles in a Distributed Simulated Driving Environment2007Självständigt arbete på grundnivå (yrkesexamen), 20 poäng / 30 hpStudentuppsats
    Abstract [en]

    In this thesis report we conducted research study on driver's behavior in T-Intersections using simulated environment. This report describes and discusses correlation analysis of driver's personality traits and style while driving at T-Intersections.

    The experiments were performed on multi user driving simulator under controlled settings, at Linköping University. A total of forty-eight people participated in the study and were divided into groups of four, all driving in the same simulated world.

    During the experiments participants were asked to fill a series of well-known self-report questionnaires. We evaluated questionnaires to get the insight in driver's personality traits and driving style. The self-report questionnaires consist of Schwartz's configural model of 10 values types and NEO-five factor inventory. Also driver's behavior was studied with the help of questionnaires based on driver's behavior, style, conflict avoidance, time horizon and tolerance of uncertainty. Then these 10 Schwartz's values are correlated with the other questionnaires to give the detail insight of the driving habits and personality traits of the drivers.

  • 10.
    Abbas, Qaisar
    Uppsala universitet, Avdelningen för teknisk databehandling.
    Weak Boundary and Interface Procedures for Wave and Flow Problems2011Doktorsavhandling, monografi (Övrigt vetenskapligt)
    Abstract [en]

    In this thesis, we have analyzed the accuracy and stability aspects of weak boundary and interface conditions (WBCs) for high order finite difference methods on Summations-By-Parts (SBP) form. The numerical technique has been applied to wave propagation and flow problems.

    The advantage of WBCs over strong boundary conditions is that stability of the numerical scheme can be proven. The boundary procedures in the advection-diffusion equation for a boundary layer problem is analyzed. By performing Navier-Stokes calculations, it is shown that most of the conclusions from the model problem carries over to the fully nonlinear case.

    The work was complemented to include the new idea of using WBCs on multiple grid points in a region, where the data is known, instead of at a single point. It was shown that we can achieve high accuracy, an increased rate of convergence to steady-state and non-reflecting boundary conditions by using this approach.

    Using the SBP technique and WBCs, we have worked out how to construct conservative and energy stable hybrid schemes for shocks using two different approaches. In the first method, we combine a high order finite difference scheme with a second order MUSCL scheme. In the second method, a procedure to locally change the order of accuracy of the finite difference schemes is developed. The main purpose is to obtain a higher order accurate scheme in smooth regions and a low order non-oscillatory scheme in the vicinity of shocks.

    Furthermore, we have analyzed the energy stability of the MUSCL scheme, by reformulating the scheme in the framework of SBP and artificial dissipation operators. It was found that many of the standard slope limiters in the MUSCL scheme do not lead to a negative semi-definite dissipation matrix, as required to get pointwise stability.

    Finally, high order simulations of shock diffracting over a convex wall with two facets were performed. The numerical study is done for a range of Reynolds numbers. By monitoring the velocities at the solid wall, it was shown that the computations were resolved in the boundary layer. Schlieren images from the computational results were obtained which displayed new interesting flow features.

  • 11.
    Abbas, Qaisar
    et al.
    Uppsala universitet, Avdelningen för teknisk databehandling.
    Nordström, Jan
    Uppsala universitet, Avdelningen för teknisk databehandling.
    Weak versus strong no-slip boundary conditions for the Navier-Stokes equations2010Ingår i: Engineering Applications of Computational Fluid Mechanics, ISSN 1994-2060, Vol. 4, s. 29-38Artikel i tidskrift (Refereegranskat)
  • 12.
    Abbas, Qaisar
    et al.
    Uppsala universitet, Avdelningen för teknisk databehandling.
    Nordström, Jan
    Uppsala universitet, Avdelningen för teknisk databehandling.
    Weak versus Strong No-Slip Boundary Conditions for the Navier-Stokes Equations2008Ingår i: Proc. 6th South African Conference on Computational and Applied Mechanics, South African Association for Theoretical and Applied Mechanics , 2008, s. 52-62Konferensbidrag (Övrigt vetenskapligt)
  • 13.
    Abbas, Qaisar
    et al.
    Uppsala universitet, Avdelningen för teknisk databehandling.
    van der Weide, Edwin
    Nordström, Jan
    Uppsala universitet, Avdelningen för teknisk databehandling.
    Accurate and stable calculations involving shocks using a new hybrid scheme2009Ingår i: Proc. 19th AIAA CFD Conference, AIAA , 2009Konferensbidrag (Refereegranskat)
  • 14.
    Abbas, Qaisar
    et al.
    Uppsala universitet, Avdelningen för teknisk databehandling.
    van der Weide, Edwin
    Faculty of Engineering Technology, University of Twente, AE Enschede, The Netherlands.
    Nordström, Jan
    Uppsala universitet, Avdelningen för teknisk databehandling.
    Energy Stability of the MUSCL Scheme2010Ingår i: Proc. 7th South African Conference on Computational and Applied Mechanics, South African Association for Theoretical and Applied Mechanics , 2010, s. 65:1-8Konferensbidrag (Övrigt vetenskapligt)
  • 15.
    Abbas, Qaisar
    et al.
    Uppsala universitet, Avdelningen för teknisk databehandling.
    van der Weide, Edwin
    Nordström, Jan
    Uppsala universitet, Avdelningen för teknisk databehandling.
    Energy stability of the MUSCL scheme2010Ingår i: Numerical Mathematics and Advanced Applications: 2009, Berlin: Springer-Verlag , 2010, s. 61-68Konferensbidrag (Refereegranskat)
  • 16.
    Abbasi, Mazhar Ali
    Linköpings universitet, Institutionen för teknik och naturvetenskap. Linköpings universitet, Tekniska högskolan.
    The synthesis, characterization and device fabrication of ZnO, NiO and their composite nanostructures2014Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Electronics industry has been revolutionized since last few decades because of the fabrication of electronic devices by using nanoscale based materials. But the more innovative feature in the electronic devices is the use of transparent materials, which makes the transparent electronic devices as one of the most interesting research field in nanoscience and nano-technology now a days. In order to have high performance electronic devices based on the wide band gap compound semiconductors, a selection of right transparent material is crucial step. Among all the transparent metal oxides, ZnO is one of the potential candidates due to the ease in the synthesis process, wide bandgap of 3.37 eV, a high exciton binding energy of 60 meV and diverse morphologies. Since p-type ZnO based nanodevices are still difficult to fabricate due to the instability and unreliability of p-type ZnO nanomaterial, therefore several p-type semiconductors are used for the development of p-n junctions. Among those NiO is suitable p-type compound semiconductor to make p-n junction with ZnO because of its wide band gap of 3.7 eV and environment friendly conditions for its synthesis. Keeping these attractive properties of n-type ZnO and p-type NiO, the synthesis of composite nanostructures of these two transparent oxides and fabrication of their electronic devices is presented in this dissertation work.

    I started my work with the synthesis of ZnO nanostructures focusing on the effect of different anions of zinc salts on the morphology and crystallinity of ZnO nanostructures. Then I grow honey-comb like NiO nanostructures on 3D nickel foam and used these nanostructures for the detection of Zinc ion. After that synthesized NiO and ZnO based composite nanostructures and characterized them, having main focus on the luminescence properties of ZnO when decorated with NiO nanostructures. The composite nanostructures of p-type NiO and n-type ZnO showed enhancement in the luminescence properties. Since pn junction is the back bone of electronic devices so working on the designing of band alignment along with the current transport properties of p-type NiO/n-type ZnO composite structures, an attempt was put forwarded to explain the phenomenon of these compound semiconducting materials. Different devices based on these two compound semiconducting materials are fabricated and designed in the present dissertation work, however still more work is required to improve the efficiency of devices like LEDs and UV detectors.

    Delarbeten
    1. Anions effect on the low temperature growth of ZnO nanostructures
    Öppna denna publikation i ny flik eller fönster >>Anions effect on the low temperature growth of ZnO nanostructures
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    2012 (Engelska)Ingår i: Vacuum, ISSN 0042-207X, E-ISSN 1879-2715, Vol. 86, nr 12, s. 1998-2001Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    Seed mediated aqueous chemical growth (ACG) route was used for the growth of ZnO nanostructures on Si substrate in four different growth mediums. The growth medium has shown to affect the morphology and the size of the different nanostructures. We observed that the medium containing zinc nitrate anions yields the nanorods, in a medium containing zinc acetate anions nano-candles are obtained. While in a medium containing zinc chloride anions ZnO nano-discs were obtained and in a medium containing zinc sulfate anions nano-flakes are achieved. Growth in these different mediums has also shown effect on the optical emission characteristics of the different ZnO nanostructures.

    Ort, förlag, år, upplaga, sidor
    Elsevier, 2012
    Nyckelord
    ZnO, Chemical growth, Nanostructures, Optical properties
    Nationell ämneskategori
    Teknik och teknologier
    Identifikatorer
    urn:nbn:se:liu:diva-84909 (URN)10.1016/j.vacuum.2012.05.020 (DOI)000308672000041 ()
    Tillgänglig från: 2012-10-26 Skapad: 2012-10-26 Senast uppdaterad: 2018-02-16
    2. Potentiometric Zinc Ion Sensor Based on Honeycomb-Like NiO Nanostructures
    Öppna denna publikation i ny flik eller fönster >>Potentiometric Zinc Ion Sensor Based on Honeycomb-Like NiO Nanostructures
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    2012 (Engelska)Ingår i: Sensors, ISSN 1424-8220, E-ISSN 1424-8220, Vol. 12, nr 11, s. 15424-15437Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    In this study honeycomb-like NiO nanostructures were grown on nickel foam by a simple hydrothermal growth method. The NiO nanostructures were characterized by field emission electron microscopy (FESEM), high resolution transmission electron microscopy (HRTEM) and X-ray diffraction (XRD) techniques. The characterized NiO nanostructures were uniform, dense and polycrystalline in the crystal phase. In addition to this, the NiO nanostructures were used in the development of a zinc ion sensor electrode by functionalization with the highly selective zinc ion ionophore 12-crown-4. The developed zinc ion sensor electrode has shown a good linear potentiometric response for a wide range of zinc ion concentrations, ranging from 0.001 mM to 100 mM, with sensitivity of 36 mV/decade. The detection limit of the present zinc ion sensor was found to be 0.0005 mM and it also displays a fast response time of less than 10 s. The proposed zinc ion sensor electrode has also shown good reproducibility, repeatability, storage stability and selectivity. The zinc ion sensor based on the functionalized NiO nanostructures was also used as indicator electrode in potentiometric titrations and it has demonstrated an acceptable stoichiometric relationship for the determination of zinc ion in unknown samples. The NiO nanostructures-based zinc ion sensor has potential for analysing zinc ion in various industrial, clinical and other real samples.

    Ort, förlag, år, upplaga, sidor
    MDPI, 2012
    Nyckelord
    honeycomb NiO nanostructures, potentiometric response, ion selective electrode, selectivity, selective ionophore
    Nationell ämneskategori
    Teknik och teknologier
    Identifikatorer
    urn:nbn:se:liu:diva-86653 (URN)10.3390/s121115424 (DOI)000311429500060 ()
    Tillgänglig från: 2012-12-20 Skapad: 2012-12-20 Senast uppdaterad: 2017-12-06
    3. Decoration of ZnO nanorods with coral reefs like NiO nanostructures by the hydrothermal growth method and their luminescence study
    Öppna denna publikation i ny flik eller fönster >>Decoration of ZnO nanorods with coral reefs like NiO nanostructures by the hydrothermal growth method and their luminescence study
    Visa övriga...
    2014 (Engelska)Ingår i: Materials, ISSN 1996-1944, E-ISSN 1996-1944, Vol. 7, nr 1, s. 430-440Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    Composite nanostructures of coral reefs like p-type NiO on n-type ZnO nanorods have been decorate on fluorine-doped tin oxide glass substrates by the hydrothermal growth. Structural characterization was performed by field emission scanning electron microscopy,  high-resolution transmission electron microscopy and X-ray diffraction techniques. This investigation has shown that the adopted synthesis has led to high crystalline quality nanostructures. Morphological study shows that the coral reefs like nanostructures are densely packed on the ZnO nanorods. Cathodoluminescence (CL) spectra for the synthesized composite nanostructures were dominated by a near band gap emission at 380 nm and by a broad interstitial defect related luminescence centered at ~630 nm. Spatially resolved CL images reveal that the luminescence originates mainly from the ZnO nanorods.

    Ort, förlag, år, upplaga, sidor
    MDPI, 2014
    Nyckelord
    ZnO nanorods; NiO nanostructure; composite nanostructures; defect states; cathodoluminescent
    Nationell ämneskategori
    Naturvetenskap
    Identifikatorer
    urn:nbn:se:liu:diva-103339 (URN)10.3390/ma7010430 (DOI)000336088500030 ()
    Tillgänglig från: 2014-01-17 Skapad: 2014-01-17 Senast uppdaterad: 2018-07-20Bibliografiskt granskad
    4. The determination of valence band offset and the current transport properties of the p-NiO/n-ZnO heterojunction
    Öppna denna publikation i ny flik eller fönster >>The determination of valence band offset and the current transport properties of the p-NiO/n-ZnO heterojunction
    Visa övriga...
    2013 (Engelska)Manuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    The electron transport in the electronic devices has significant influence on the device performance, thus current transport properties determination is highly demanded for a particular device. Herein, we report the facile hydrothermal growth method based fabrication of p-NiO/n-ZnO heterojunction. The material characterization was performed by scanning electron microscopy, X-ray diffraction, transmission electron microscopy and X-ray photo electron spectroscopy. These techniques provided the good crystal quality, pure phase of p-NiO and n-ZnO nanostructures respectively. The measured valance band offset of composite nanostructure is 2.25 eV and conduction band offset was found to be 2.58 eV. The current transport properties of the fabricated p-n junction are governed by three different I-V regions. The impedance spectroscopy was used for the determination of the role of grain boundaries at the interface.

    Nyckelord
    Zinc oxide, nickel oxide, heterojunction, diode, current transport properties
    Nationell ämneskategori
    Naturvetenskap
    Identifikatorer
    urn:nbn:se:liu:diva-103340 (URN)
    Tillgänglig från: 2014-01-17 Skapad: 2014-01-17 Senast uppdaterad: 2014-03-27Bibliografiskt granskad
    5. Fabrication of UV photo-detector based on coral reef like p-NiO/n-ZnO nanocomposite structures
    Öppna denna publikation i ny flik eller fönster >>Fabrication of UV photo-detector based on coral reef like p-NiO/n-ZnO nanocomposite structures
    Visa övriga...
    2013 (Engelska)Ingår i: Materials letters (General ed.), ISSN 0167-577X, E-ISSN 1873-4979, Vol. 108, s. 149-152Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    In this research work, a UV photo-detector is fabricated on fluorine doped tin oxide (FTO) glass substrate by exploiting the advantageous features of p-n heterojunctions based on p-NiO and n-ZnO composite nanostructures forming a coral-reef like structures. Scanning electron microscopy (SEM) and X-ray diffraction results showed uniform morphology and good crystal quality of the synthesised nanostructures respectively. I-V measurements have shown nonlinear and rectifying response of the p-NiO/n-ZnO heterojunction. The proposed photodiode exhibited excellent UV response with acceptable photocurrent generation of about 3.4 mA and the responsivity of 2.27 A/W at -3 biasing voltage.

    Ort, förlag, år, upplaga, sidor
    Elsevier, 2013
    Nyckelord
    p-NiO/n-ZnO composite nanostructures, Photodiode, UV-visible spectrophotometry
    Nationell ämneskategori
    Teknik och teknologier
    Identifikatorer
    urn:nbn:se:liu:diva-99403 (URN)10.1016/j.matlet.2013.06.083 (DOI)000324562900038 ()
    Tillgänglig från: 2013-10-17 Skapad: 2013-10-17 Senast uppdaterad: 2017-12-06
    6. The fabrication of white light-emitting diodes using the n-ZnO/NiO/p-GaN heterojunction with enhanced luminescence
    Öppna denna publikation i ny flik eller fönster >>The fabrication of white light-emitting diodes using the n-ZnO/NiO/p-GaN heterojunction with enhanced luminescence
    Visa övriga...
    2013 (Engelska)Ingår i: Nanoscale Research Letters, ISSN 1931-7573, E-ISSN 1556-276X, Vol. 8, nr 320Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    Cheap and efficient white light-emitting diodes (LEDs) are of great interest due to the energy crisis all over the world. Herein, we have developed heterojunction LEDs based on the well-aligned ZnO nanorods and nanotubes on the p-type GaN with the insertion of the NiO buffer layer that showed enhancement in the light emission. Scanning electron microscopy have well demonstrated the arrays of the ZnO nanorods and the proper etching into the nanotubes. X-ray diffraction study describes the wurtzite crystal structure array of ZnO nanorods with the involvement of GaN at the (002) peak. The cathodoluminescence spectra represent strong and broad visible emission peaks compared to the UV emission and a weak peak at 425 nm which is originated from GaN. Electroluminescence study has shown highly improved luminescence response for the LEDs fabricated with NiO buffer layer compared to that without NiO layer. Introducing a sandwich-thin layer of NiO between the n-type ZnO and the p-type GaN will possibly block the injection of electrons from the ZnO to the GaN. Moreover, the presence of NiO buffer layer might create the confinement effect.

    Nyckelord
    White light-emitting diode; ZnO nanorods; Nanotubes; NiO buffer layer
    Nationell ämneskategori
    Naturvetenskap
    Identifikatorer
    urn:nbn:se:liu:diva-103341 (URN)10.1186/1556-276X-8-320 (DOI)000331642900001 ()
    Tillgänglig från: 2014-01-17 Skapad: 2014-01-17 Senast uppdaterad: 2017-12-06Bibliografiskt granskad
  • 17.
    Abbasi, Mazhar Ali
    et al.
    Linköpings universitet, Institutionen för teknik och naturvetenskap. Linköpings universitet, Tekniska högskolan.
    Hussain Ibupoto, Zafar
    Linköpings universitet, Institutionen för teknik och naturvetenskap. Linköpings universitet, Tekniska högskolan.
    Hussain, Mushtaque
    Linköpings universitet, Institutionen för teknik och naturvetenskap. Linköpings universitet, Tekniska högskolan.
    Nur, Omer
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik och elektroteknik. Linköpings universitet, Tekniska högskolan.
    Willander, Magnus
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik och elektroteknik. Linköpings universitet, Tekniska högskolan.
    The fabrication of white light-emitting diodes using the n-ZnO/NiO/p-GaN heterojunction with enhanced luminescence2013Ingår i: Nanoscale Research Letters, ISSN 1931-7573, E-ISSN 1556-276X, Vol. 8, nr 320Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Cheap and efficient white light-emitting diodes (LEDs) are of great interest due to the energy crisis all over the world. Herein, we have developed heterojunction LEDs based on the well-aligned ZnO nanorods and nanotubes on the p-type GaN with the insertion of the NiO buffer layer that showed enhancement in the light emission. Scanning electron microscopy have well demonstrated the arrays of the ZnO nanorods and the proper etching into the nanotubes. X-ray diffraction study describes the wurtzite crystal structure array of ZnO nanorods with the involvement of GaN at the (002) peak. The cathodoluminescence spectra represent strong and broad visible emission peaks compared to the UV emission and a weak peak at 425 nm which is originated from GaN. Electroluminescence study has shown highly improved luminescence response for the LEDs fabricated with NiO buffer layer compared to that without NiO layer. Introducing a sandwich-thin layer of NiO between the n-type ZnO and the p-type GaN will possibly block the injection of electrons from the ZnO to the GaN. Moreover, the presence of NiO buffer layer might create the confinement effect.

  • 18.
    Abbasi, Mazhar Ali
    et al.
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik och elektroteknik. Linköpings universitet, Tekniska högskolan.
    Hussain Ibupoto, Zafar
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik och elektroteknik. Linköpings universitet, Tekniska högskolan.
    Hussain, Mushtaque
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik och elektroteknik. Linköpings universitet, Tekniska högskolan.
    Pozina, Galia
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Lu, Jun
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Nur, Omer
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik och elektroteknik. Linköpings universitet, Tekniska högskolan.
    Willander, Magnus
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik och elektroteknik. Linköpings universitet, Tekniska högskolan.
    Decoration of ZnO nanorods with coral reefs like NiO nanostructures by the hydrothermal growth method and their luminescence study2014Ingår i: Materials, ISSN 1996-1944, E-ISSN 1996-1944, Vol. 7, nr 1, s. 430-440Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Composite nanostructures of coral reefs like p-type NiO on n-type ZnO nanorods have been decorate on fluorine-doped tin oxide glass substrates by the hydrothermal growth. Structural characterization was performed by field emission scanning electron microscopy,  high-resolution transmission electron microscopy and X-ray diffraction techniques. This investigation has shown that the adopted synthesis has led to high crystalline quality nanostructures. Morphological study shows that the coral reefs like nanostructures are densely packed on the ZnO nanorods. Cathodoluminescence (CL) spectra for the synthesized composite nanostructures were dominated by a near band gap emission at 380 nm and by a broad interstitial defect related luminescence centered at ~630 nm. Spatially resolved CL images reveal that the luminescence originates mainly from the ZnO nanorods.

  • 19.
    Abbey-Lee, Robin
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biologi. Linköpings universitet, Tekniska fakulteten. Max Planck Inst Ornithol, Germany.
    Araya-Ajoy, Yimen G.
    Norwegian Univ Sci and Technol, Norway.
    Mouchet, Alexia
    Max Planck Inst Ornithol, Germany.
    Moiron, Maria
    Max Planck Inst Ornithol, Germany.
    Stuber, Erica F.
    Univ Nebraska Lincoln, NE USA.
    Kempenaers, Bart
    Max Planck Inst Ornithol, Germany.
    Dingemanse, Niels J.
    Max Planck Inst Ornithol, Germany; Ludwig Maximilians Univ Munchen, Germany.
    Does perceived predation risk affect patterns of extra-pair paternity? A field experiment in a passerine bird2018Ingår i: Functional Ecology, ISSN 0269-8463, E-ISSN 1365-2435, Vol. 32, nr 4, s. 1001-1010Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Non-consumptive predator effects have been shown to influence a wide range of behavioural, life history and morphological traits. Extra-pair reproduction is widespread among socially monogamous birds and may incur predation costs. Consequently, altered rates of extra-pair reproduction are expected in circumstances characterized by increased adult perceived predation risk. In addition, extra-pair reproduction is expected to be most affected for birds with phenotypes that generally increase predation risk (such as more active individuals). In two consecutive years, perceived predation risk was manipulated for great tits Parus major breeding in 12 nest-box plots by broadcasting sounds of their main predator (European sparrowhawk Accipiter nisus; six plots). As a control treatment, sounds of a sympatric, avian non-predator species were broadcast (Eurasian blackbird Turdus merula; six plots). Levels of extra-pair paternity did not differ between plots with different predation risk treatments. Males that moved more in a novel environment (more active or faster exploring) tended to have offspring with fewer partners, but this effect did not vary with predation risk treatment. From an adaptive viewpoint, predation costs associated with extra-pair reproduction may be small and may not outweigh the benefits of extra-pair behaviour. Research on a broader range of taxa with different mating strategies is now needed to confirm the generality of our findings.

  • 20.
    Abbey-Lee, Robin N.
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biologi. Linköpings universitet, Tekniska fakulteten.
    Uhrig, Emily J.
    Department of Zoology, Stockholm University, 10691 Stockholm, Sweden.
    Zidar, Josefina
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biologi. Linköpings universitet, Tekniska fakulteten.
    Favati, Anna
    Department of Zoology, Stockholm University, 10691 Stockholm, Sweden.
    Almberg, Johan
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biologi. Linköpings universitet, Tekniska fakulteten.
    Dahlblom, Josefin
    Department of Neuroscience, Uppsala Biomedical Centre BMC, Uppsala University, Uppsala, Sweden.
    Winberg, Svante
    Department of Neuroscience, Uppsala Biomedical Centre BMC, Uppsala University, Uppsala, Sweden.
    Løvlie, Hanne
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biologi. Linköpings universitet, Tekniska fakulteten.
    The influence of rearing on behavior, brain monoamines and gene expression in three-spined sticklebacks2018Dataset
    Abstract [en]
    1. The causes of individual variation in behavior are often not well understood, and potential underlying mechanisms include both intrinsic and extrinsic factors, such as early environmental, physiological, and genetic differences.
    2. In an exploratory laboratory study, we raised three-spined sticklebacks (Gasterosteus aculeatus) under 4 different environmental conditions (simulated predator environment, complex environment, variable social environment, and control). We investigated how these manipulations related to behavior, brain physiology and gene expression later in life, with focus on brain dopamine and serotonin levels, turnover rates, and gene expression.
    3. The different rearing environments influenced behavior and gene expression, but did not alter monoamine levels or metabolites. Specifically, compared to control fish, fish exposed to a simulated predator environment tended to be less aggressive, more exploratory, and more neophobic; and fish raised in both complex and variable social environments tended to be less neophobic. Exposure to a simulated predator environment tended to lower expression of dopamine receptor DRD4A, a complex environment increased expression of dopamine receptor DRD1B, while a variable social environment tended to increase serotonin receptor 5-HTR2B and increased serotonin transporter SLC6A4A expression. Despite both behavior and gene expression varying with early environment, there was no evidence that gene expression mediated the relationship between early environment and behavior.
    4. Our results confirm that environmental conditions early in life can affect phenotypic variation. However, the mechanistic pathway of the monoaminergic systems translating early environmental variation into observed behavioral responses was not detected.
  • 21.
    Abbey-Lee, Robin N.
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biologi. Linköpings universitet, Tekniska fakulteten.
    Uhrig, Emily
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biologi. Linköpings universitet, Tekniska fakulteten.
    Zidar, Josefina
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biologi. Linköpings universitet, Tekniska fakulteten.
    Favati, A.
    Department of Zoology, Stockholm University, Stockholm, Sweden.
    Almberg, J.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biologi. Linköpings universitet, Tekniska fakulteten.
    Dahlbom, J.
    Department of Neuroscience, Uppsala Biomedical Centre BMC, Uppsala University, Uppsala, Sweden.
    Winberg, S.
    Department of Neuroscience, Uppsala Biomedical Centre BMC, Uppsala University, Uppsala, Sweden.
    Løvlie, Hanne
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biologi. Linköpings universitet, Tekniska fakulteten.
    The Influence of Rearing on Behavior, Brain Monoamines, and Gene Expression in Three-Spined Sticklebacks2018Ingår i: Brain, behavior, and evolution, ISSN 0006-8977, E-ISSN 1421-9743, Vol. 91, nr 4, s. 201-213Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The causes of individual variation in behavior are often not well understood, and potential underlying mechanisms include both intrinsic and extrinsic factors, such as early environmental, physiological, and genetic differences. In an exploratory laboratory study, we raised three-spined sticklebacks <i>(Gasterosteus aculeatus)</i> under 4 different environmental conditions (simulated predator environment, complex environment, variable social environment, and control). We investigated how these manipulations related to behavior, brain physiology, and gene expression later in life, with focus on brain dopamine and serotonin levels, turnover rates, and gene expression. The different rearing environments influenced behavior and gene expression, but did not alter monoamine levels or metabolites. Specifically, compared to control fish, fish exposed to a simulated predator environment tended to be less aggressive, more exploratory, and more neophobic; and fish raised in both complex and variable social environments tended to be less neophobic. Exposure to a simulated predator environment tended to lower expression of dopamine receptor DRD4A, a complex environment increased expression of dopamine receptor DRD1B, while a variable social environment tended to increase serotonin receptor 5-HTR2B and serotonin transporter SLC6A4A expression. Despite both behavior and gene expression varying with early environment, there was no evidence that gene expression mediated the relationship between early environment and behavior. Our results confirm that environmental conditions early in life can affect phenotypic variation. However, the mechanistic pathway of the monoaminergic systems translating early environmental variation into observed behavioral responses was not detected.

  • 22.
    Abdalla, Hassan
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Komplexa material och system. Linköpings universitet, Tekniska fakulteten.
    Charge and Energy Transport in Disordered Organic Semiconductors2018Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Improvement of the performance of organic disordered semiconductors (OSC) is driven by the understanding   of the underlying charge transport mechanisms and systematic exploitation thereof. There exists a multitude of materials and material systems based on polymers and small molecules with promising performance for use in organic light emitting diodes, photovoltaics, organic field-effect transistors and thermoelectrics. However, universal understanding of many classes of these materials has eluded researchers, due to their broad   spectrum of morphologies, molecular structures and electrical properties. Building on the large body of existing models, this thesis deals with charge transport phenomena from the perspective of transport energetics, by studying the interplay between a few but important concepts commonly accepted to play a crucial role in all  OSC materials; energetic disorder, charge carrier hopping and Coulomb interactions. The influence of these concepts on the energetic landscape through which charge carriers move and how this translates to experimentally observed transport phenomena are studied by a combination of experimental work, kinetic Monte Carlo (MC) simulations and empirical and analytical models.

    The universal scaling and collapse of the temperature and electric field dependence of the conductivity of PEDOT:PSS to a single curve is shown to be functionally equivalent to the scaling of the effective temperature, which describes the effect of field heating as a broadening of the charge carrier distribution. From numerical investigation of the energy relaxation, an empirical model is developed that relates the physical meaning   behind both concepts to the heat balance between Joule heating of the carrier distribution via the effective temperature and energy loss to the lattice. For this universal description to be applicable a strongly energy- dependent density of states (DOS) as well as Coulomb interactions and large carrier concentrations are needed.

    Chemical doping is a common way of improving charge transport in OSC and is also beneficial for energy transport, which combined leads to an increased thermoelectric power factor. The ensuing thermoelectric investigations not only showed the potential of these materials for use in thermoelectric generators, but are  also helpful in unraveling charge transport mechanism as they give direct insight into the energetics of a material. Interestingly, doped OSC exhibit the same universal power-law relationship between thermopower and conductivity, independent of material system or doping method, pointing towards a common energy and charge transport mechanism. In this thesis an analytical model is presented, which reproduces said universal power-law behavior and is able to attribute it to Variable Range Hopping (VRH) or a transition between Nearest Neighbour Hopping (NNH) and VRH at higher concentrations. This model builds on an existing three- dimensional hopping formalism that includes the effect of the attractive Coulomb potential of ionized dopants that leads to a broadening of the DOS. Here, this model is extended by including the energy offset between   host and dopant material and is positively tested against MC simulations and a set of thermoelectric measurements covering different material groups and doping mechanisms.

    Organic field effect transistors (OFETs) have become increasingly comparable in electrical mobility to their inorganic (silicon) counterparts. The spatial extent of charge transport in OFETs has been subject to debate since their inception with many experimental, numerical and analytical studies having been undertaken. Here it is shown that the common way of analyzing the dimensionality of charge transport in OFETs may be prone to misinterpretations. Instead, the results in this thesis suggest that charge transport in OFETs is, in fact, quasi- two-dimensional (2D) due to the confinement of the gate field in addition to a morphology-induced preferred in-plane direction of the transport. The inherently large charge carrier concentrations in OFETs in addition to   the quasi-2D confinement leads to increased Coulomb interaction between charge carriers as compared to bulk material, leading to a thermoelectric behavior that deviates from doped organic systems. At very large concentrations interesting charge transport phenomena are observed, including an unexpected simultaneous increase of the concentration dependence and the magnitude of the mobility, the appearance of a negative transconductance, indicating a transition to an insulating Mott-Hubbard phase. The experimental and   numerical results in this thesis relate these phenomena the intricacies of the interplay between Coulomb interactions, energetic disorder and charge carrier hopping.

    Delarbeten
    1. Effective Temperature and Universal Conductivity Scaling in Organic Semiconductors
    Öppna denna publikation i ny flik eller fönster >>Effective Temperature and Universal Conductivity Scaling in Organic Semiconductors
    2015 (Engelska)Ingår i: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 5, artikel-id 16870Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    We investigate the scalability of the temperature-and electric field-dependence of the conductivity of disordered organic semiconductors to universal curves by two different but commonly employed methods; by so-called universal scaling and by using the effective temperature concept. Experimentally both scaling methods were found to be equally applicable to the out-of-plane charge transport in PEDOT: PSS thin films of various compositions. Both methods are shown to be equivalent in terms of functional dependence and to have identical limiting behavior. The experimentally observed scaling behavior can be reproduced by a numerical nearest-neighbor hopping model, accounting for the Coulomb interaction, the high charge carrier concentration and the energetic disorder. The underlying physics can be captured in a simple empirical model, describing the effective temperature of the charge carrier distribution as the outcome of a heat balance between Joule heating and (effective) temperature-dependent energy loss to the lattice.

    Ort, förlag, år, upplaga, sidor
    Nature Publishing Group, 2015
    Nationell ämneskategori
    Fysik
    Identifikatorer
    urn:nbn:se:liu:diva-123329 (URN)10.1038/srep16870 (DOI)000364933800002 ()26581975 (PubMedID)
    Tillgänglig från: 2015-12-14 Skapad: 2015-12-11 Senast uppdaterad: 2018-10-08
    2. Impact of doping on the density of states and the mobility in organic semiconductors
    Öppna denna publikation i ny flik eller fönster >>Impact of doping on the density of states and the mobility in organic semiconductors
    2016 (Engelska)Ingår i: PHYSICAL REVIEW B, ISSN 2469-9950, Vol. 93, nr 23, s. 235203-Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    We experimentally investigated conductivity and mobility of poly(3-hexylthiophene) (P3HT) doped with tetrafluorotetracyanoquinodimethane (F(4)TCNQ) for various relative doping concentrations ranging from ultralow (10(-5)) to high (10(-1)) and various active layer thicknesses. Although the measured conductivity monotonously increases with increasing doping concentration, the mobilities decrease, in agreement with previously published work. Additionally, we developed a simple yet quantitative model to rationalize the results on basis of a modification of the density of states (DOS) by the Coulomb potentials of ionized dopants. The DOS was integrated in a three-dimensional (3D) hopping formalism in which parameters such as energetic disorder, intersite distance, energy level difference, and temperature were varied. We compared predictions of our model as well as those of a previously developed model to kinetic Monte Carlo (MC) modeling and found that only the former model accurately reproduces the mobility of MC modeling in a large part of the parameter space. Importantly, both our model and MC simulations are in good agreement with experiments; the crucial ingredient to both is the formation of a deep trap tail in the Gaussian DOS with increasing doping concentration.

    Ort, förlag, år, upplaga, sidor
    AMER PHYSICAL SOC, 2016
    Nationell ämneskategori
    Annan fysik
    Identifikatorer
    urn:nbn:se:liu:diva-130276 (URN)10.1103/PhysRevB.93.235203 (DOI)000378813800009 ()
    Anmärkning

    Funding Agencies|Chinese Scholarship Council (CSC)

    Tillgänglig från: 2016-08-01 Skapad: 2016-07-28 Senast uppdaterad: 2018-08-29
    3. Range and energetics of charge hopping in organic semiconductors
    Öppna denna publikation i ny flik eller fönster >>Range and energetics of charge hopping in organic semiconductors
    2017 (Engelska)Ingår i: Physical Review B, ISSN 2469-9950, E-ISSN 2469-9969, Vol. 96, nr 24, artikel-id 241202Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    The recent upswing in attention for the thermoelectric properties of organic semiconductors (OSCs) adds urgency to the need for a quantitative description of the range and energetics of hopping transport in organic semiconductors under relevant circumstances, i.e., around room temperature (RT). In particular, the degree to which hops beyond the nearest neighbor must be accounted for at RT is still largely unknown. Here, measurements of charge and energy transport in doped OSCs are combined with analytical modeling to reach the univocal conclusion that variable-range hopping is the proper description in a large class of disordered OSC at RT. To obtain quantitative agreement with experiment, one needs to account for the modification of the density of states by ionized dopants. These Coulomb interactions give rise to a deep tail of trap states that is independent of the materials initial energetic disorder. Insertion of this effect into a classical Mott-type variable-range hopping model allows one to give a quantitative description of temperature-dependent conductivity and thermopower measurements on a wide range of disordered OSCs. In particular, the model explains the commonly observed quasiuniversal power-law relation between the Seebeck coefficient and the conductivity.

    Ort, förlag, år, upplaga, sidor
    AMER PHYSICAL SOC, 2017
    Nationell ämneskategori
    Den kondenserade materiens fysik
    Identifikatorer
    urn:nbn:se:liu:diva-144143 (URN)10.1103/PhysRevB.96.241202 (DOI)000418616700001 ()
    Anmärkning

    Funding Agencies|Chinese Scholarship Council (CSC); Knut och Alice Wallenberg stiftelse

    Tillgänglig från: 2018-01-10 Skapad: 2018-01-10 Senast uppdaterad: 2018-08-29
    4. Investigation of the dimensionality of charge transport in organic field effect transistors
    Öppna denna publikation i ny flik eller fönster >>Investigation of the dimensionality of charge transport in organic field effect transistors
    2017 (Engelska)Ingår i: Physical Review B, ISSN 2469-9950, E-ISSN 2469-9969, Vol. 95, nr 8, artikel-id 85301Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    Ever since the first experimental investigations of organic field effect transistors (OFETs) the dimensionality of charge transport has alternately been described as two dimensional (2D) and three dimensional (3D). More recently, researchers have turned to an analytical analysis of the temperature-dependent transfer characteristics to classify the dimensionality as either 2D or 3D as well as to determine the disorder of the system, thereby greatly simplifying dimensionality investigations. We applied said analytical analysis to the experimental results of our OFETs comprising molecularly well-defined polymeric layers as the active material as well as to results obtained from kinetic Monte Carlo simulations and found that it was not able to correctly distinguish between 2D and 3D transports or give meaningful values for the disorder and should only be used for quasiquantitative and comparative analysis. We conclude to show that the dimensionality of charge transport in OFETs is a function of the interplay between transistor physics and morphology of the organic material.

    Ort, förlag, år, upplaga, sidor
    AMER PHYSICAL SOC, 2017
    Nationell ämneskategori
    Den kondenserade materiens fysik
    Identifikatorer
    urn:nbn:se:liu:diva-138929 (URN)10.1103/PhysRevB.95.085301 (DOI)000402194500006 ()
    Anmärkning

    Funding Agencies|Knut och Alice Wallenbergs stiftelse; Advanced Functional Materials Center at Linkoping University [2009-00971]; VINNOVA [2015-04859]

    Tillgänglig från: 2017-06-27 Skapad: 2017-06-27 Senast uppdaterad: 2018-03-14
  • 23.
    Abdalla, Hassan
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Komplexa material och system. Linköpings universitet, Tekniska fakulteten.
    Fabiano, Simone
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik och elektroteknik. Linköpings universitet, Tekniska fakulteten.
    Kemerink, Martijn
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Komplexa material och system. Linköpings universitet, Tekniska fakulteten.
    Investigation of the dimensionality of charge transport in organic field effect transistors2017Ingår i: Physical Review B, ISSN 2469-9950, E-ISSN 2469-9969, Vol. 95, nr 8, artikel-id 85301Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Ever since the first experimental investigations of organic field effect transistors (OFETs) the dimensionality of charge transport has alternately been described as two dimensional (2D) and three dimensional (3D). More recently, researchers have turned to an analytical analysis of the temperature-dependent transfer characteristics to classify the dimensionality as either 2D or 3D as well as to determine the disorder of the system, thereby greatly simplifying dimensionality investigations. We applied said analytical analysis to the experimental results of our OFETs comprising molecularly well-defined polymeric layers as the active material as well as to results obtained from kinetic Monte Carlo simulations and found that it was not able to correctly distinguish between 2D and 3D transports or give meaningful values for the disorder and should only be used for quasiquantitative and comparative analysis. We conclude to show that the dimensionality of charge transport in OFETs is a function of the interplay between transistor physics and morphology of the organic material.

  • 24.
    Abdalla, Hassan
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Komplexa material och system. Linköpings universitet, Tekniska fakulteten.
    van de Ruit, Kevin
    Eindhoven University of Technology, Netherlands.
    Kemerink, Martijn
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Komplexa material och system. Linköpings universitet, Tekniska fakulteten. Eindhoven University of Technology, Netherlands.
    Effective Temperature and Universal Conductivity Scaling in Organic Semiconductors2015Ingår i: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 5, artikel-id 16870Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We investigate the scalability of the temperature-and electric field-dependence of the conductivity of disordered organic semiconductors to universal curves by two different but commonly employed methods; by so-called universal scaling and by using the effective temperature concept. Experimentally both scaling methods were found to be equally applicable to the out-of-plane charge transport in PEDOT: PSS thin films of various compositions. Both methods are shown to be equivalent in terms of functional dependence and to have identical limiting behavior. The experimentally observed scaling behavior can be reproduced by a numerical nearest-neighbor hopping model, accounting for the Coulomb interaction, the high charge carrier concentration and the energetic disorder. The underlying physics can be captured in a simple empirical model, describing the effective temperature of the charge carrier distribution as the outcome of a heat balance between Joule heating and (effective) temperature-dependent energy loss to the lattice.

  • 25.
    Abdalla, Hassan
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Komplexa material och system. Linköpings universitet, Tekniska fakulteten.
    Zuo, Guangzheng
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Komplexa material och system. Linköpings universitet, Tekniska fakulteten.
    Kemerink, Martijn
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Komplexa material och system. Linköpings universitet, Tekniska fakulteten.
    Range and energetics of charge hopping in organic semiconductors2017Ingår i: Physical Review B, ISSN 2469-9950, E-ISSN 2469-9969, Vol. 96, nr 24, artikel-id 241202Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The recent upswing in attention for the thermoelectric properties of organic semiconductors (OSCs) adds urgency to the need for a quantitative description of the range and energetics of hopping transport in organic semiconductors under relevant circumstances, i.e., around room temperature (RT). In particular, the degree to which hops beyond the nearest neighbor must be accounted for at RT is still largely unknown. Here, measurements of charge and energy transport in doped OSCs are combined with analytical modeling to reach the univocal conclusion that variable-range hopping is the proper description in a large class of disordered OSC at RT. To obtain quantitative agreement with experiment, one needs to account for the modification of the density of states by ionized dopants. These Coulomb interactions give rise to a deep tail of trap states that is independent of the materials initial energetic disorder. Insertion of this effect into a classical Mott-type variable-range hopping model allows one to give a quantitative description of temperature-dependent conductivity and thermopower measurements on a wide range of disordered OSCs. In particular, the model explains the commonly observed quasiuniversal power-law relation between the Seebeck coefficient and the conductivity.

  • 26.
    Abdallah, Nancy
    et al.
    Linköpings universitet, Matematiska institutionen, Matematik och tillämpad matematik. Linköpings universitet, Tekniska fakulteten.
    Hultman, Axel
    Linköpings universitet, Matematiska institutionen, Matematik och tillämpad matematik. Linköpings universitet, Tekniska fakulteten.
    Combinatorial invariance of Kazhdan-Lusztig-Vogan polynomials for fixed point free involutions2018Ingår i: Journal of Algebraic Combinatorics, ISSN 0925-9899, E-ISSN 1572-9192, Vol. 47, nr 4, s. 543-560Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    When acts on the flag variety of , the orbits are in bijection with fixed point free involutions in the symmetric group . In this case, the associated Kazhdan-Lusztig-Vogan polynomials can be indexed by pairs of fixed point free involutions , where denotes the Bruhat order on . We prove that these polynomials are combinatorial invariants in the sense that if is a poset isomorphism of upper intervals in the Bruhat order on fixed point free involutions, then for all v amp;gt;= u.

  • 27.
    Abdelfattah, Ahmed
    et al.
    Univ Mediterranea Reggio Calabria, Italy.
    Malacrinò, Antonino
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biologi. Linköpings universitet, Tekniska fakulteten.
    Wisniewski, Michael
    USDA ARS, WV 25430 USA.
    Cacciola, Santa O.
    Univ Catania, Italy.
    Schena, Leonardo
    Univ Mediterranea Reggio Calabria, Italy.
    Metabarcoding: A powerful tool to investigate microbial communities and shape future plant protection strategies2018Ingår i: Biological control (Print), ISSN 1049-9644, E-ISSN 1090-2112, Vol. 120Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Microorganisms are the main drivers shaping the functioning and equilibrium of all ecosystems, contributing to nutrient cycling, primary production, litter decomposition, and multi-trophic interactions. Knowledge about the microbial assemblies in specific ecological niches is integral to understanding the assemblages interact and function the function, and becomes essential when the microbiota intersects with human activities, such as protecting crops against pests and diseases. Metabarcoding has proven to be a valuable tool and has been widely used for characterizing the microbial diversity of different environments and has been utilized in many research endeavors. Here we summarize the current status of metabarcoding technologies, the advantages and challenges in utilizing this technique, and how this pioneer approach is being applied to studying plant diseases and pests, with a focus on plant protection and biological control. Current and future developments in this technology will foster a more comprehensive understanding of microbial ecology, and the development of new, innovative pest control strategies.

  • 28.
    Abdollahi Sani, Negar
    et al.
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik och elektroteknik. Linköpings universitet, Tekniska högskolan.
    Robertsson, Mats
    Linköpings universitet, Institutionen för teknik och naturvetenskap. Linköpings universitet, Tekniska högskolan.
    Cooper, Philip
    De La Rue Plc, Overton, Hampshire, UK .
    Wang, Xin
    Acreo AB, Norrköping, Sweden.
    Svensson, Magnus
    Acreo AB, Norrköping, Sweden.
    Andersson Ersman, Peter
    Acreo AB, Norrköping, Sweden.
    Norberg, Petronella
    Acreo AB, Norrköping, Sweden.
    Nilsson, Marie
    Acreo AB, Norrköping, Sweden.
    Nilsson, David
    Acreo AB, Norrköping, Sweden.
    Liu, Xianjie
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Ytors Fysik och Kemi. Linköpings universitet, Tekniska högskolan.
    Hesselbom, Hjalmar
    Hesselbom Innovation and Development HB, Huddinge, Sweden .
    Akesso, Laurent
    De La Rue Plc, Overton, Hampshire, UK .
    Fahlman, Mats
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Ytors Fysik och Kemi. Linköpings universitet, Tekniska högskolan.
    Crispin, Xavier
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik och elektroteknik. Linköpings universitet, Tekniska högskolan.
    Engquist, Isak
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik och elektroteknik. Linköpings universitet, Tekniska högskolan.
    Berggren, Magnus
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik och elektroteknik. Linköpings universitet, Tekniska högskolan. Acreo AB, Norrköping, Sweden.
    Gustafsson, Goran
    Acreo AB, Norrköping, Sweden.
    All-printed diode operating at 1.6 GHz2014Ingår i: Proceedings of the National Academy of Sciences of the United States of America, ISSN 0027-8424, E-ISSN 1091-6490, Vol. 111, nr 33, s. 11943-11948Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Printed electronics are considered for wireless electronic tags and sensors within the future Internet-of-things (IoT) concept. As a consequence of the low charge carrier mobility of present printable organic and inorganic semiconductors, the operational frequency of printed rectifiers is not high enough to enable direct communication and powering between mobile phones and printed e-tags. Here, we report an all-printed diode operating up to 1.6 GHz. The device, based on two stacked layers of Si and NbSi2 particles, is manufactured on a flexible substrate at low temperature and in ambient atmosphere. The high charge carrier mobility of the Si microparticles allows device operation to occur in the charge injection-limited regime. The asymmetry of the oxide layers in the resulting device stack leads to rectification of tunneling current. Printed diodes were combined with antennas and electrochromic displays to form an all-printed e-tag. The harvested signal from a Global System for Mobile Communications mobile phone was used to update the display. Our findings demonstrate a new communication pathway for printed electronics within IoT applications.

  • 29.
    Abdolmajid Ahmad, Bookan
    Linköpings universitet, Institutionen för datavetenskap. Linköpings universitet, Tekniska högskolan.
    Programmering av generativ konst i C# .Net2014Självständigt arbete på grundnivå (kandidatexamen), 180 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Detta examensarbete utfördes på IDA (Institutionen för datavetenskap) vid Linköpings universitet. 

    Syftet med det här examensarbetet var att utveckla ett program som skulle skapa förutsättningar för generativ konst med hjälp av MyPaint som är ett digitalt rit/målarverktyg. Metoden gick ut på att registrera vad användaren skapat för komponenter, dvs. musinteraktioner och kortkommandon, och därefter använda dem algoritmiskt.

    Examensarbetet resulterades i ett program (SharpArt), som fångar musinteraktioner samt simulerar tangentbordstryckningar (kortkommandon) från och till Mypaint, vilket i sin tur skapar komponenter som används algoritmiskt. Programmet kan även positionera objektet på canvasen enligt det önskade koordinatvärdet.

  • 30.
    Abdulahad, Bassam
    et al.
    Linköpings universitet, Institutionen för datavetenskap.
    Lounis, Georgios
    Linköpings universitet, Institutionen för datavetenskap.
    A user interface for the ontology merging tool SAMBO2004Självständigt arbete på grundnivå (yrkesexamen)Studentuppsats
    Abstract [en]

    Ontologies have become an important tool for representing data in a structured manner. Merging ontologies allows for the creation of ontologies that later can be composed into larger ontologies as well as for recognizing patterns and similarities between ontologies. Ontologies are being used nowadays in many areas, including bioinformatics. In this thesis, we present a desktop version of SAMBO, a system for merging ontologies that are represented in the languages OWL and DAML+OIL. The system has been developed in the programming language JAVA with JDK (Java Development Kit) 1.4.2. The user can open a file locally or from the network and can merge ontologies using suggestions generated by the SAMBO algorithm. SAMBO provides a user-friendly graphical interface, which guides the user through the merging process.

  • 31.
    Abdulla, Ariyan
    et al.
    Linköpings universitet, Matematiska institutionen, Optimeringslära. Linköpings universitet, Tekniska fakulteten.
    Andersson, Erik
    Linköpings universitet, Matematiska institutionen, Optimeringslära. Linköpings universitet, Tekniska fakulteten.
    Heuristiska algoritmer för schemaläggning i real-tidssystem med hänsyn till data beroenden2018Självständigt arbete på grundnivå (kandidatexamen), 10,5 poäng / 16 hpStudentuppsats (Examensarbete)
    Abstract [en]

    The schedule for the jobs in a real-time system can have a huge impact on how the system behave. Since real-time systems are common in safety applications it is important that the scheduling is done in a valid way. Furthermore, one can enhance the performance of the applications by minimizing data latency and jitter. A challenge is that jobs in real-time systems usually have complex constraints making it too time consuming to minimize data latency and jitter to optimality. The purpose of this report is to investigate the possibility of creating high quality schedules using heuristics, with the goal to keep the computational time under one minute. This will be done by comparing three different algorithms that will be used on real scheduling instances provided by the company Arcticus. The first algorithm is a greedy heuristic, the second one a local search and the third one is a metaheuristic, simulated annealing. The results indicate that the data latency can be reduced whilst keeping the computational time below one minute.

  • 32.
    Abdulla, Parosh Aziz
    et al.
    Department of Information Technology, Uppsala University, Sweden.
    Atig, Mohamed Faouzi
    Department of Information Technology, Uppsala University, Sweden.
    Chen, Yu-Fang
    Institute of Information Science, Academia Sinica, Taiwan.
    Holik, Lukas
    Faculty of Information Technology, Brno University of Technology, Czech Republic.
    Rezine, Ahmed
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska högskolan.
    Rümmer, Philipp
    Department of Information Technology, Uppsala University, Sweden.
    Stenman, Jari
    Department of Information Technology, Uppsala University, Sweden.
    String Constraints for Verification2014Ingår i: 26th International Conference on Computer Aided Verification (CAV 2014), Vienna, Austria, Jul. 9-12, 2014., Berlin: Springer, 2014, s. 150-166Konferensbidrag (Refereegranskat)
    Abstract [en]

    We present a decision procedure for a logic that combines (i) word equations over string variables denoting words of arbitrary lengths, together with (ii) constraints on the length of words, and on (iii) the regular languages to which words belong. Decidability of this general logic is still open. Our procedure is sound for the general logic, and a decision procedure for a particularly rich fragment that restricts the form in which word equations are written. In contrast to many existing procedures, our method does not make assumptions about the maximum length of words. We have developed a prototypical implementation of our decision procedure, and integrated it into a CEGAR-based model checker for the analysis of programs encoded as Horn clauses. Our tool is able to automatically establish the correctness of several programs that are beyond the reach of existing methods.

  • 33.
    Abdulla, Parosh Aziz
    et al.
    Uppsala University, Sweden.
    Atig, Mohamed Faouzi
    Uppsala University, Sweden.
    Chen, Yu-Fang
    Academia Sinica, Taiwan.
    Leonardsson, Carl
    Uppsala University, Sweden.
    Rezine, Ahmed
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska högskolan.
    Automatic fence insertion in integer programs via predicate abstraction2012Ingår i: Static Analysis: 19th International Symposium, SAS 2012, Deauville, France, September 11-13, 2012. Proceedings / [ed] Antoine Miné, David Schmidt, Springer Berlin/Heidelberg, 2012, s. 164-180Konferensbidrag (Refereegranskat)
    Abstract [en]

    We propose an automatic fence insertion and verification framework for concurrent programs running under relaxed memory. Unlike previous approaches to this problem, which allow only variables of finite domain, we target programs with (unbounded) integer variables. The problem is difficult because it has two different sources of infiniteness: unbounded store buffers and unbounded integer variables. Our framework consists of three main components: (1) a finite abstraction technique for the store buffers, (2) a finite abstraction technique for the integer variables, and (3) a counterexample guided abstraction refinement loop of the model obtained from the combination of the two abstraction techniques. We have implemented a prototype based on the framework and run it successfully on all standard benchmarks together with several challenging examples that are beyond the applicability of existing methods.

  • 34.
    Abdulla, Parosh Aziz
    et al.
    Uppsala University, Sweden.
    Atig, Mohamed Faouzi
    Uppsala University, Sweden.
    Chen, Yu-Fang
    Academia Sinica, Taiwan.
    Leonardsson, Carl
    Uppsala University, Sweden.
    Rezine, Ahmed
    Linköpings universitet, Institutionen för datavetenskap, ESLAB - Laboratoriet för inbyggda system. Linköpings universitet, Tekniska högskolan.
    Counter-Example Guided Fence Insertion under TSO2012Ingår i: TACAS 2012, Berlin, Heidelberg: Springer , 2012Konferensbidrag (Refereegranskat)
    Abstract [en]

    We give a sound and complete fence insertion procedure for concurrentfinite-state programs running under the classical TSO memory model. Thismodel allows “write to read” relaxation corresponding to the addition of an unboundedstore buffer between each processor and the main memory. We introducea novel machine model, called the Single-Buffer (SB) semantics, and show thatthe reachability problem for a program under TSO can be reduced to the reachabilityproblem under SB. We present a simple and effective backward reachabilityanalysis algorithm for the latter, and propose a counter-example guided fence insertionprocedure. The procedure is augmented by a placement constraint thatallows the user to choose places inside the program where fences may be inserted.For a given placement constraint, we automatically infer all minimal setsof fences that ensure correctness. We have implemented a prototype and run itsuccessfully on all standard benchmarks together with several challenging examplesthat are beyond the applicability of existing methods.

  • 35.
    Abdulla, Parosh Aziz
    et al.
    Uppsala University, Sweden.
    Atig, Mohamed Faouzi
    Uppsala University, Sweden.
    Chen, Yu-Fang
    Academia Sinica, Taiwan.
    Leonardsson, Carl
    Uppsala University, Sweden.
    Rezine, Ahmed
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska högskolan.
    Memorax, a Precise and Sound Tool for Automatic Fence Insertion under TSO2013Ingår i: Tools and Algorithms for the Construction and Analysis of Systems: 19th International Conference, TACAS 2013, Held as Part of the European Joint Conferences on Theory and Practice of Software, ETAPS 2013, Rome, Italy, March 16-24, 2013. Proceedings, Springer Berlin/Heidelberg, 2013, s. 530-536Konferensbidrag (Refereegranskat)
    Abstract [en]

    We introduce MEMORAX, a tool for the verification of control state reachability (i.e., safety properties) of concurrent programs manipulating finite range and integer variables and running on top of weak memory models. The verification task is non-trivial as it involves exploring state spaces of arbitrary or even infinite sizes. Even for programs that only manipulate finite range variables, the sizes of the store buffers could grow unboundedly, and hence the state spaces that need to be explored could be of infinite size. In addition, MEMORAX in- corporates an interpolation based CEGAR loop to make possible the verification of control state reachability for concurrent programs involving integer variables. The reachability procedure is used to automatically compute possible memory fence placements that guarantee the unreachability of bad control states under TSO. In fact, for programs only involving finite range variables and running on TSO, the fence insertion functionality is complete, i.e., it will find all minimal sets of memory fence placements (minimal in the sense that removing any fence would result in the reachability of the bad control states). This makes MEMORAX the first freely available, open source, push-button verification and fence insertion tool for programs running under TSO with integer variables.

  • 36.
    Abdulla, Parosh Aziz
    et al.
    Uppsala University.
    Atig, Mohammed Faouzi
    Uppsala University.
    Ganjei, Zeinab
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    Rezine, Ahmed
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska högskolan.
    Zhu, Yunyun
    Uppsala University.
    Verification of Cache Coherence Protocols wrt. Trace Filters2015Konferensbidrag (Refereegranskat)
    Abstract [en]

    We address the problem of parameterized verification of cache coherence protocols for hardware accelerated transactional memories. In this setting, transactional memories leverage on the versioning capabilities of the underlying cache coherence protocol. The length of the transactions, their number, and the number of manipulated variables (i.e., cache lines) are parameters of the verification problem. Caches in such systems are finite-state automata communicating via broadcasts and shared variables. We augment our system with filters that restrict the set of possible executable traces according to existing conflict resolution policies. We show that the verification of coherence for parameterized cache protocols with filters can be reduced to systems with only a finite number of cache lines. For verification, we show how to account for the effect of the adopted filters in a symbolic backward reachability algorithm based on the framework of constrained monotonic abstraction. We have implemented our method and used it to verify transactional memory coherence protocols with respect to different conflict resolution policies.

  • 37.
    Abdulla, Parosh Aziz
    et al.
    Uppsala University, Sweden.
    Dwarkadas, Sandhya
    University of Rochester, U.S.A..
    Rezine, Ahmed
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska högskolan.
    Shriraman, Arrvindh
    Simon Fraser University, Canada.
    Zhu, Yunyun
    Uppsala University, Sweden.
    Verifying Safety and Liveness for the FlexTM Hybrid Transactional Memory2013Ingår i: Design, Automation & Test in Europe (DATE 2013), Grenoble, France, March 18-22, 2013., IEEE , 2013, s. 785-790Konferensbidrag (Refereegranskat)
    Abstract [en]

    We consider the verification of safety (strict se- rializability and abort consistency) and liveness (obstruction and livelock freedom) for the hybrid transactional memory framework FLEXTM. This framework allows for flexible imple- mentations of transactional memories based on an adaptation of the MESI coherence protocol. FLEXTM allows for both eager and lazy conflict resolution strategies. Like in the case of Software Transactional Memories, the verification problem is not trivial as the number of concurrent transactions, their size, and the number of accessed shared variables cannot be a priori bounded. This complexity is exacerbated by aspects that are specific to hardware and hybrid transactional memories. Our work takes into account intricate behaviours such as cache line based conflict detection, false sharing, invisible reads or non-transactional instructions. We carry out the first automatic verification of a hybrid transactional memory and establish, by adopting a small model approach, challenging properties such as strict serializability, abort consistency, and obstruction freedom for both an eager and a lazy conflict resolution strategies. We also detect an example that refutes livelock freedom. To achieve this, our prototype tool makes use the latest antichain based techniques to handle systems with tens of thousands of states.

  • 38.
    Abdulla, Parosh Aziz
    et al.
    Uppsala University.
    Haziza, Frédéric
    Uppsala University.
    Holik, Lukas
    Brno University of Technology, Czech Republic.
    Jonsson, Bengt
    Uppsala University.
    Rezine, Ahmed
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska högskolan.
    An Integrated Specification and Verification Technique for Highly Concurrent Data Structures2013Ingår i: The 19th International Conference on Tools and Algorithms for the Construction and Analysis of Systems (TACAS 2013), Rome, Italy, March 16-24, 2013. / [ed] Piterman, Nir, Smolka, Scott, 2013Konferensbidrag (Refereegranskat)
    Abstract [en]

    We present a technique for automatically verifying safety properties of concurrent programs, in particular programs which rely on subtle dependencies of local states of different threads, such as lock-free implementations of stacks and queues in an environment without garbage collection. Our technique addresses the joint challenges of infinite-state specifications, an unbounded number of threads, and an unbounded heap managed by explicit memory allocation. Our technique builds on the automata-theoretic approach to model checking, in which a specification is given by an automaton that observes the execution of a program and accepts executions that violate the intended specification.We extend this approach by allowing specifications to be given by a class of infinite-state automata. We show how such automata can be used to specify queues, stacks, and other data structures, by extending a data-independence argument. For verification, we develop a shape analysis, which tracks correlations between pairs of threads, and a novel abstraction to make the analysis practical. We have implemented our method and used it to verify programs, some of which have not been verified by any other automatic method before.

  • 39.
    Abdullah Jan, Mirza
    et al.
    Linköpings universitet, Institutionen för systemteknik.
    Ahsan, Mahmododfateh
    Linköpings universitet, Institutionen för systemteknik.
    Multi-View Video Transmission over the Internet2010Självständigt arbete på avancerad nivå (masterexamen), 30 poäng / 45 hpStudentuppsats (Examensarbete)
    Abstract [en]

    3D television using multiple views rendering is receiving increasing interest. In this technology a number of video sequences are transmitted simultaneously and provides a larger view of the scene or stereoscopic viewing experience. With two views stereoscopic rendition is possible. Nowadays 3D displays are available that are capable of displaying several views simultaneously and the user is able to see different views by moving his head.

    The thesis work aims at implementing a demonstration system with a number of simultaneous views. The system will include two cameras, computers at both the transmitting and receiving end and a multi-view display. Besides setting up the hardware, the main task is to implement software so that the transmission can be done over an IP-network.

    This thesis report includes an overview and experiences of similar published systems, the implementation of real time video, its compression, encoding, and transmission over the internet with the help of socket programming and finally the multi-view display in 3D format.  This report also describes the design considerations more precisely regarding the video coding and network protocols.

  • 40.
    Abellán, C.
    et al.
    ICFO - Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, Barcelona, Spain.
    Acín, A.
    ICFO - Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, Barcelona, Spain / ICREA - Institució Catalana de Recerca i Estudis Avançats, Barcelona, Spain.
    Alarcón, A.
    Millennium Institute for Research in Optics, Universidad de Concepción, Universidad de Concepción, Concepción, Chile / Departamento de Ingeniería Eléctrica, Universidad de Concepción, Concepción, Chile.
    Alibart, O.
    Université Côte d’Azur, CNRS UMR 7010, Institut de Physique de Nice (INPHYNI), Nice, France.
    Andersen, C. K.
    Department of Physics, ETH Zurich,, Zurich, Switzerland.
    Andreoli, F.
    Dipartimento di Fisica, Sapienza Università di Roma, Rome, Italy.
    Beckert, A.
    Department of Physics, ETH Zurich,, Zurich, Switzerland.
    Beduini, F. A.
    ICFO - Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, Barcelona, Spain.
    Bendersky, A.
    Departamento de Computación, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires and Instituto de Investigación en Ciencias de la Comunicación (ICC), CONICET, Buenos Aires, Argentina.
    Bentivegna, M.
    Dipartimento di Fisica, Sapienza Università di Roma, Rome, Italy.
    Bierhorst, P.
    National Institute of Standards and Technology, Boulder, CO, USA.
    Burchardt, D.
    Ludwig-Maximilians-Universität, Munich, Germany.
    Cabello, A.
    Departamento de Física Aplicada II, Universidad de Sevilla, Seville, Spain.
    Cariñe, J.
    Millennium Institute for Research in Optics, Universidad de Concepción, Universidad de Concepción, Concepción, Chile.
    Carrasco, S.
    ICFO - Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, Barcelona, Spain.
    Carvacho, G.
    Dipartimento di Fisica, Sapienza Università di Roma, Rome, Italy.
    Cavalcanti, D.
    Chaves, R.
    Cortés-Vega, J.
    Cuevas, A.
    Delgado, A.
    de Riedmatten, H.
    Eichler, C.
    Farrera, P.
    Fuenzalida, J.
    García-Matos, M.
    Garthoff, R.
    Gasparinetti, S.
    Gerrits, T.
    Ghafari Jouneghani, F.
    Glancy, S.
    Gómez, E. S.
    González, P.
    Guan, J. -Y.
    Handsteiner, J.
    Heinsoo, J.
    Heintze, G.
    Hirschmann, A.
    Jiménez, O.
    Kaiser, F.
    Knill, E.
    Knoll, L. T.
    Krinner, S.
    Kurpiers, P.
    Larotonda, M. A.
    Larsson, Jan-Åke
    Linköpings universitet, Institutionen för systemteknik, Informationskodning. Linköpings universitet, Tekniska fakulteten.
    Lenhard, A.
    Li, H.
    Li, M. -H.
    Lima, G.
    Liu, B.
    Liu, Y.
    López Grande, I. H.
    Lunghi, T.
    Ma, X.
    Magaña-Loaiza, O. S.
    Magnard, P.
    Magnoni, A.
    Martí­-Prieto, M.
    Martínez, D.
    Mataloni, P.
    Mattar, A.
    Mazzera, M.
    Mirin, R. P.
    Mitchell, M. W.
    Nam, S.
    Oppliger, M.
    Pan, J. -W.
    Patel, R. B.
    Pryde, G. J.
    Rauch, D.
    Redeker, K.
    Rieländer, D.
    Ringbauer, M.
    Roberson, T.
    Rosenfeld, W.
    Salathé, Y.
    Santodonato, L.
    Sauder, G.
    Scheidl, T.
    Schmiegelow, C. T.
    Sciarrino, F.
    Seri, A.
    Shalm, L. K.
    Shi, S. -C
    Slussarenko, S.
    Stevens, M. J.
    Tanzilli, S.
    Toledo, F.
    Tura, J.
    Ursin, R.
    Vergyris, P.
    Verma, V. B.
    Walter, T.
    Wallraff, A.
    Wang, Z.
    Weinfurter, H.
    Weston, M. M.
    White, A. G.
    Wu, C.
    Xavier, Guilherme B.
    Linköpings universitet, Institutionen för systemteknik, Informationskodning. Linköpings universitet, Tekniska fakulteten.
    You, L.
    Yuan, X.
    Zeilinger, A.
    Zhang, Q.
    Zhang, W.
    Zhong, J.
    Challenging Local Realism with Human Choices2018Ingår i: Nature, ISSN 0028-0836, E-ISSN 1476-4687, Vol. 557, s. 212-216Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A Bell test is a randomized trial that compares experimental observations against the philosophical worldview of local realism , in which the properties of the physical world are independent of our observation of them and no signal travels faster than light. A Bell test requires spatially distributed entanglement, fast and high-efficiency detection and unpredictable measurement settings. Although technology can satisfy the first two of these requirements, the use of physical devices to choose settings in a Bell test involves making assumptions about the physics that one aims to test. Bell himself noted this weakness in using physical setting choices and argued that human ‘free will’ could be used rigorously to ensure unpredictability in Bell tests. Here we report a set of local-realism tests using human choices, which avoids assumptions about predictability in physics. We recruited about 100,000 human participants to play an online video game that incentivizes fast, sustained input of unpredictable selections and illustrates Bell-test methodology. The participants generated 97,347,490 binary choices, which were directed via a scalable web platform to 12 laboratories on five continents, where 13 experiments tested local realism using photons, single atoms, atomic ensembles and superconducting devices. Over a 12-hour period on 30 November 2016, participants worldwide provided a sustained data flow of over 1,000 bits per second to the experiments, which used different human-generated data to choose each measurement setting. The observed correlations strongly contradict local realism and other realistic positions in bi-partite and tri-partite 12 scenarios. Project outcomes include closing the ‘freedom-of-choice loophole’ (the possibility that the setting choices are influenced by ‘hidden variables’ to correlate with the particle properties), the utilization of video-game methods for rapid collection of human-generated randomness, and the use of networking techniques for global participation in experimental science.

  • 41.
    Abidin, Aysajan
    Linköpings universitet, Matematiska institutionen, Tillämpad matematik. Linköpings universitet, Tekniska högskolan.
    Weaknesses of Authentication in Quantum Cryptography and Strongly Universal Hash Functions2010Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Authentication is an indispensable part of Quantum Cryptography, which is an unconditionally secure key distribution technique based on the laws of nature. Without proper authentication, Quantum Cryptography is vulnerable to “man-in-the-middle” attacks. Therefore, to guarantee unconditional security of any Quantum Cryptographic protocols, the authentication used must also be unconditionally secure. The standard in Quantum Cryptography is to use theWegman-Carter authentication, which is unconditionally secure and is based on the idea of universal hashing.

    In this thesis, we first investigate properties of a Strongly Universal hash function family to facilitate understanding the properties of (classical) authentication used in Quantum Cryptography. Then, we study vulnerabilities of a recently proposed authentication protocol intended to rule out a "man-in-the-middle" attack on Quantum Cryptography. Here, we point out that the proposed authentication primitive is not secure when used in a generic Quantum Cryptographic protocol. Lastly, we estimate the lifetime of authentication using encrypted tags when the encryption key is partially known. Under simplifying assumptions, we derive that the lifetime is linearly dependent on the length of the authentication key. Experimental results that support the theoretical results are also presented.

    Delarbeten
    1. Special Properties of Strongly Universal2 Hash Functions Important in Quantum Cryptography
    Öppna denna publikation i ny flik eller fönster >>Special Properties of Strongly Universal2 Hash Functions Important in Quantum Cryptography
    2009 (Engelska)Ingår i: AIP Conference Proceedings, ISSN 0094-243X, Foundations of Probability and Physics—5, Växjö, augusti 2008, New York: American Institute of Physics , 2009, Vol. 1101, s. 289-293Konferensbidrag, Publicerat paper (Refereegranskat)
    Abstract [en]

    Secure message authentication is an important part of Quantum Key Distribution. In this paper we analyze special properties of a Strongly Universal2 hash function family, an understanding of which is important in the security analysis of the authentication used in Quantum Cryptography. We answer the following question: How much of Alices message does Eve need to influence so that the message along with its tag will give her enough information to create the correct tag for her message?

    Ort, förlag, år, upplaga, sidor
    New York: American Institute of Physics, 2009
    Nyckelord
    Quantum cryptography, Quantum theory, Probability
    Nationell ämneskategori
    Matematik
    Identifikatorer
    urn:nbn:se:liu:diva-18738 (URN)10.1063/1.3109951 (DOI)
    Konferens
    Foundations of Probability and Physics—5, Växjö, augusti 2008
    Projekt
    ICG QC
    Tillgänglig från: 2009-06-03 Skapad: 2009-06-03 Senast uppdaterad: 2016-08-31
    2. Vulnerability of "A Novel Protocol-Authentication Algorithm Ruling out a Man-in-the-Middle Attack in Quantum Cryptography"
    Öppna denna publikation i ny flik eller fönster >>Vulnerability of "A Novel Protocol-Authentication Algorithm Ruling out a Man-in-the-Middle Attack in Quantum Cryptography"
    2009 (Engelska)Ingår i: International Journal of Quantum Information, ISSN 0219-7499, Vol. 7, nr 5, s. 1047-1052Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    In this paper, we review and comment on "A novel protocol-authentication algorithm ruling out a man-in-the-middle attack in quantum cryptography" [M. Peev et al., Int. J. Quant. Inf. 3 (2005) 225]. In particular, we point out that the proposed primitive is not secure when used in a generic protocol, and needs additional authenticating properties of the surrounding quantum-cryptographic protocol.

    Nyckelord
    Quantum cryptography, quantum key distribution, authentication
    Nationell ämneskategori
    Naturvetenskap
    Identifikatorer
    urn:nbn:se:liu:diva-20405 (URN)10.1142/S0219749909005754 (DOI)
    Projekt
    ICG QC
    Tillgänglig från: 2009-09-08 Skapad: 2009-09-07 Senast uppdaterad: 2016-08-31Bibliografiskt granskad
    3. Lifetime of Authentication Using Encrypted Tags When the Encryption Key is Partially Known
    Öppna denna publikation i ny flik eller fönster >>Lifetime of Authentication Using Encrypted Tags When the Encryption Key is Partially Known
    (Engelska)Manuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    Quantum cryptography is an unconditionally secure key growing technique provided that an unconditionally secure authentication protocol is combined with it. This paper is about the study of the lifetime of a message authentication scheme, where a message to be authenticated is first hashed by a secret–but fixed–Strongly Universal hash function then the output is encrypted with a one-time-pad key to generate a tag for the message. If the onetime-pad is completely secret, then the lifetime is exponential in the tag length. If, however, the one-time-pad key is partially known in each authentication round, as is the case in practical quantum key distribution protocols, then the picture is different; because the adversary’s partial knowledge of the one-time-pad key in each authentication round contributes to his/her ability to identify the secret hash function. We estimate the lifetime of this type of authentication. Here the parameters are the length of the key identifying the secret hash function and the amount of knowledge that Eve has on the one-time-pad. A theoretical estimate is presented, along with experimental results that support it.

    Nyckelord
    Quantum cryptography, quantum key distribution, authentication, strongly universal hash functions, lifetime
    Nationell ämneskategori
    Matematik
    Identifikatorer
    urn:nbn:se:liu:diva-57289 (URN)
    Projekt
    ICG QC
    Tillgänglig från: 2010-06-16 Skapad: 2010-06-16 Senast uppdaterad: 2016-08-31
  • 42.
    Abidin, Aysajan
    et al.
    Linköpings universitet, Matematiska institutionen. Linköpings universitet, Tekniska högskolan.
    Larsson, Jan-Åke
    Linköpings universitet, Matematiska institutionen, Tillämpad matematik. Linköpings universitet, Tekniska högskolan.
    Lifetime of Authentication Using Encrypted Tags When the Encryption Key is Partially KnownManuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    Quantum cryptography is an unconditionally secure key growing technique provided that an unconditionally secure authentication protocol is combined with it. This paper is about the study of the lifetime of a message authentication scheme, where a message to be authenticated is first hashed by a secret–but fixed–Strongly Universal hash function then the output is encrypted with a one-time-pad key to generate a tag for the message. If the onetime-pad is completely secret, then the lifetime is exponential in the tag length. If, however, the one-time-pad key is partially known in each authentication round, as is the case in practical quantum key distribution protocols, then the picture is different; because the adversary’s partial knowledge of the one-time-pad key in each authentication round contributes to his/her ability to identify the secret hash function. We estimate the lifetime of this type of authentication. Here the parameters are the length of the key identifying the secret hash function and the amount of knowledge that Eve has on the one-time-pad. A theoretical estimate is presented, along with experimental results that support it.

  • 43.
    Abidin, Aysajan
    et al.
    Linköpings universitet, Matematiska institutionen, Tillämpad matematik. Linköpings universitet, Tekniska högskolan.
    Larsson, Jan-Åke
    Linköpings universitet, Matematiska institutionen, Tillämpad matematik. Linköpings universitet, Tekniska högskolan.
    Special Properties of Strongly Universal2 Hash Functions Important in Quantum Cryptography2009Ingår i: AIP Conference Proceedings, ISSN 0094-243X, Foundations of Probability and Physics—5, Växjö, augusti 2008, New York: American Institute of Physics , 2009, Vol. 1101, s. 289-293Konferensbidrag (Refereegranskat)
    Abstract [en]

    Secure message authentication is an important part of Quantum Key Distribution. In this paper we analyze special properties of a Strongly Universal2 hash function family, an understanding of which is important in the security analysis of the authentication used in Quantum Cryptography. We answer the following question: How much of Alices message does Eve need to influence so that the message along with its tag will give her enough information to create the correct tag for her message?

  • 44.
    Abidin, Aysajan
    et al.
    Linköpings universitet, Matematiska institutionen, Tillämpad matematik. Linköpings universitet, Tekniska högskolan.
    Larsson, Jan-Åke
    Linköpings universitet, Matematiska institutionen, Tillämpad matematik. Linköpings universitet, Tekniska högskolan.
    Vulnerability of "A Novel Protocol-Authentication Algorithm Ruling out a Man-in-the-Middle Attack in Quantum Cryptography"2009Ingår i: International Journal of Quantum Information, ISSN 0219-7499, Vol. 7, nr 5, s. 1047-1052Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this paper, we review and comment on "A novel protocol-authentication algorithm ruling out a man-in-the-middle attack in quantum cryptography" [M. Peev et al., Int. J. Quant. Inf. 3 (2005) 225]. In particular, we point out that the proposed primitive is not secure when used in a generic protocol, and needs additional authenticating properties of the surrounding quantum-cryptographic protocol.

  • 45.
    Abidin, Aysajan
    et al.
    Linköpings universitet, Institutionen för systemteknik, Informationskodning. Linköpings universitet, Tekniska högskolan.
    Pacher, Christoph
    Austrian Institute of Technology, Austria.
    Lorünser, Thomas
    Austrian Institute of Technology, Austria.
    Larsson, Jan-Åke
    Linköpings universitet, Institutionen för systemteknik, Informationskodning. Linköpings universitet, Tekniska högskolan.
    Peev, Momtchil
    Austrian Institute of Technology, Austria.
    Quantum cryptography and authentication with low key-consumption2011Ingår i: Proceedings of SPIE - The International Society for Optical Engineering, 2011, s. 818916-Konferensbidrag (Refereegranskat)
    Abstract [en]

    Quantum Key Distribution (QKD - also referred to as Quantum Cryptography) is a technique for secret key agreement. It has been shown that QKD rigged with Information-Theoretic Secure (ITS) authentication (using secret key) of the classical messages transmitted during the key distribution protocol is also ITS. Note, QKD without any authentication can trivially be broken by man-in-the-middle attacks. Here, we study an authentication method that was originally proposed because of its low key consumption; a two-step authentication that uses a publicly known hash function, followed by a secret strongly universal2 hash function, which is exchanged each round. This two-step authentication is not information-theoretically secure but it was argued that nevertheless it does not compromise the security of QKD. In the current contribution we study intrinsic weaknesses of this approach under the common assumption that the QKD adversary has access to unlimited resources including quantum memories. We consider one implementation of Quantum Cryptographic protocols that use such authentication and demonstrate an attack that fully extract the secret key. Even including the final key from the protocol in the authentication does not rule out the possibility of these attacks. To rectify the situation, we propose a countermeasure that, while not informationtheoretically secure, restores the need for very large computing power for the attack to work. Finally, we specify conditions that must be satisfied by the two-step authentication in order to restore informationtheoretic security.

  • 46.
    Abongo, D. A.
    et al.
    University of Nairobi, Kenya.
    Wandiga, S. O.
    University of Nairobi, Kenya.
    Jumba, I. O.
    University of Nairobi, Kenya.
    Van den Brink, P. J.
    University of Wageningen and Research Centre, Netherlands.
    Naziriwo, B. B.
    Makerere University, Uganda.
    Madadi, V. O.
    University of Nairobi, Kenya.
    Wafula, G. A.
    University of Nairobi, Kenya.
    Nkedi-Kizza, P.
    University of Florida, FL USA.
    Kylin, Henrik
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Filosofiska fakulteten. North West University, South Africa.
    Occurrence, abundance and distribution of benthic macroinvertebrates in the Nyando River catchment, Kenya2015Ingår i: African Journal of Aquatic Science, ISSN 1608-5914, E-ISSN 1727-9364, Vol. 40, nr 4, s. 373-392Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A baseline study was conducted of the occurrence of macroinvertebrates at 26 sites in the Nyando River catchment in 2005-2006. A total of 13 orders and 16 families of Arthropoda, Mollusca, Platyhelminthes and Annelida were collected, with the order Ephemeroptera being most abundant in the up- and mid-stream reaches, followed by Hemiptera and Plecoptera respectively. The downstream sections of the river were dominated by Hirudinea and tubificids, as the water quality deteriorated mainly due to local land use, raw sewage effluent discharge and annual floods. Insects and annelids were the main invertebrates found and the extent of pollution increased from mid-section (Site 15) downwards as the river flowed into the Winam Gulf. Stringent management measures are required to safeguard the environment and ecosystems of Lake Victoria.

  • 47.
    Abong'o, Deborah
    et al.
    University of Nairobi, Kenya.
    Wandiga, Shem
    University of Nairobi, Kenya.
    Jumba, Isaac
    University of Nairobi, Kenya.
    Madadi, Vincent
    University of Nairobi, Kenya.
    Kylin, Henrik
    Linköpings universitet, Institutionen för tema, Tema vatten i natur och samhälle. Linköpings universitet, Filosofiska fakulteten.
    Impacts of pesticides on human health and environment in the River Nyando catchment, Kenya2014Ingår i: International Journal of Humanities, Arts, Medicine and Sciences, ISSN 2348-0521, Vol. 2, nr 3, s. 1-14Artikel i tidskrift (Övrigt vetenskapligt)
    Abstract [en]

    The population of the River Nyando catchment largely relies on rain fed agriculture for their subsistence.

    Important crops grown include cereals, cash crops fruits and vegetables. Farming is one of the contributors of pollution to Lake Victoria. Organophosphates and other banned organochlorine pesticides such as lindane, aldrin and dieldrin were used by farmers. The pesticides transport was by storm water run-off and air drift into the lake. Environmental risk assessment background information was collected through questionnaire and interviews of farmers to determine knowledge and safe use of pesticides. Fourteen pesticides were identified as commonly used of which four are toxic to bees and five to birds. The farmers identified declines in the number of pollinating insects, the disappearance of Red-billed Oxpecker (Buphagus erythrorthynchus) and wild bird’s fatalities. The general knowledge among farmers about chemicals risks, safety, and chronic illnesses was low. Activities that increases environmental awareness and safety of pesticides should be initiated by the agrochemical firms and government.

  • 48.
    Abong'o, Deborah
    et al.
    University of Nairobi, Kenya.
    Wandiga, Shem
    University of Nairobi. Kenya.
    Jumba, Isac
    University of Nairobi, Kenya.
    van den Brink, Paul
    Wageningen University, the Netherlands.
    Nazariwo, Betty
    Makerere University, Uganda.
    Madadi, Vincent
    University of Nairobi, Kenya.
    Wafula, Godfrey
    University of Nairobi, Kenya.
    Kylin, Henrik
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Filosofiska fakulteten.
    Nkedi-Kizza, Peter
    University of Florida, USA.
    Organochlorine pesticide residue levels in soil from the Nyando River catchment, Kenya2015Ingår i: Africa Journal of Physical Sciences, ISSN 2313-3317, Vol. 2, nr 1, s. 18-32Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Soil samples were collected from six locations representative of the Nyando River catchment area of the Lake Victoria over a period of two years. Sampling was done four times in the year in February, May, September and December 2005 and 2006 in farms where maize, tea, sugar cane, coffee, rice and vegetables have been grown over the years. This coincided with the effects of different seasons and farming activities on residue levels of the pesticides in use. The objective was to investigate levels and distribution of organochlorine pesticides that have either been banned or are restricted for use in Kenya. Organochlorine pesticides investigated were DDT, lindane, aldrin, dieldrin, heptachlor, endrin, endosulfan (both α- and β- isomers and endosulfan sulphate), the sum is called “total” or Σendosulfan and methoxychlor. Prior to the ban or restriction in use, these pesticides had found wide applications in public health for control of disease vectors and in agriculture for control of crop pests. The analysis revealed presence of all the targeted pesticides with the highest mean concentrations for methoxychlor 140 ± 1.5 μg/kg, Σendosulfan (30 ± 2.1 μg/kg), aldrin (18 ± 0.28 μg/kg), respectively. The results show the presence of these pesticides in soils in the basin and this could be impacting negatively on the ecosystem health of the area.

  • 49.
    Abraham-Nordling, Mirna
    et al.
    Karolinska institutet.
    Persson, Bengt
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Bioinformatik. Linköpings universitet, Tekniska högskolan.
    Nordling, Erik
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Bioinformatik. Linköpings universitet, Tekniska högskolan.
    Model of the complex of Parathyroid hormone-2receptor and Tuberoinfundibular peptide of39 residues2010Ingår i: BMC Reseach Notes, ISSN 1756-0500, Vol. 3, nr 270Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Background

    We aim to propose interactions between the parathyroid hormone-2 receptor (PTH2R) and its ligand the tuberoinfundibular peptide of 39 residues (TIP39) by constructing a homology model of their complex. The two related peptides parathyroid hormone (PTH) and parathyroid hormone related protein (PTHrP) are compared with the complex to examine their interactions.

    Findings

    In the model, the hydrophobic N-terminus of TIP39 is buried in a hydrophobic part of the central cavity between helices 3 and 7. Comparison of the peptide sequences indicates that the main discriminator between the agonistic peptides TIP39 and PTH and the inactive PTHrP is a tryptophan-phenylalanine replacement. The model indicates that the smaller phenylalanine in PTHrP does not completely occupy the binding site of the larger tryptophan residue in the other peptides. As only TIP39 causes internalisation of the receptor and the primary difference being an aspartic acid in position 7 of TIP39 that interacts with histidine 396 in the receptor, versus isoleucine/histidine residues in the related hormones, this might be a trigger interaction for the events that cause internalisation.

    Conclusions

    A model is constructed for the complex and a trigger interaction for full agonistic activation between aspartic acid 7 of TIP39 and histidine 396 in the receptor is proposed.

  • 50.
    Abrahamsson, Björn
    Linköpings universitet, Institutionen för systemteknik.
    Architectures for Multiplication in Galois Rings2004Självständigt arbete på grundnivå (yrkesexamen)Studentuppsats
    Abstract [en]

    This thesis investigates architectures for multiplying elements in Galois rings of the size 4^m, where m is an integer.

    The main question is whether known architectures for multiplying in Galois fields can be used for Galois rings also, with small modifications, and the answer to that question is that they can.

    Different representations for elements in Galois rings are also explored, and the performance of multipliers for the different representations is investigated.

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