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  • 2051.
    Ahlsten, Nanna
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Martín-Matute, Belén
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Rhodium-catalysed coupling of allylic, homoallylic, and bishomoallylic alcohols with aldehydes and N-tosylimines: insights into the mechanism2009In: Advanced Synthesis and Catalysis, ISSN 1615-4150, E-ISSN 1615-4169, Vol. 351, no 16, p. 2657-2666Article in journal (Refereed)
    Abstract [en]

    The isomerisation of alkenols followed by reaction with aldehydes or N-tosylimines catalysed by rhodium complexes has been studied. The catalytically active rhodium complex is formed in situ from commercially available (cyclooctadiene)rhodium(l) chloride dimer [Rh(COD)Cl](2). The tandem process affords aldol and Mannich-type products in excellent yields. The key to the success of the coupling reaction is the activation of the catalysts by reaction with postassium tert-butoxide (t-BuOK), which promotes a catalytic cycle via alkoxides rather than rhodium hydrides. This mechanism minimises the formation of unwanted by-products. The mechanism has been studied by (1)H NMR spectroscopy and deuterium labelling experiments.

  • 2052.
    Ahlstrand, Pernilla
    Stockholm University, Faculty of Humanities, Department of Ethnology, History of Religions and Gender Studies.
    Att kunna lyssna med kroppen: En studie av gestaltande förmåga inom gymnasieskolans estetiska program, inriktning teater2014Doctoral thesis, monograph (Other academic)
    Abstract [en]

    Theatre has been a school subject in the Swedish upper secondary school's national arts program since 1992 and has its own syllabus and grading criteria. The National Curriculum in theatre emphasises the development of performative capability, which is the focus of this dissertation. This study aims to contribute to the improvement of teachers’ subject-specific language, and concerns certain aspects of student ways of knowing.

    Theatre encompasses tacit knowledge (Lagerström 2003) and as an art form belongs to a tradition of practical knowledge. Knowledge in theatre has traditionally been acquired within a master-apprentice tradition (Johansson 2012, Järleby 2003). When theatre as an art form becomes a school subject the conditions of the art form change through a didactic transposition (Chevallard 2005). The previous two curriculum reforms in Sweden have developed competency-based syllabuses. To meet the school's requirements for planning teaching activities with colleagues as well as assessing and giving feedback to students, theatre knowledge needs to be articulated. Research is therefore needed to develop a professional language among teachers within the subject of theatre.

    I have chosen to work with Learning study, which is a collaborative and iterative research approach which enables the articulation of teachers and students knowing. Data is analysed using foremost phenomenographic analyses. The results generated in this study could be useful for teachers in the process of planning lessons, giving feedback to students, for assessments and grades, for discussing the content of lessons with other teachers, and ultimately for us to begin to recognize different levels of knowing.

  • 2053.
    Ahlstrand, Pernilla
    Stockholm University, Faculty of Humanities, Department of Ethnology, History of Religions and Gender Studies.
    "Inte ett öga torrt" - en studie rörande ämnesdidaktiska val i teaterundervisning2015In: Forskning om undervisning och lärande, ISSN 2000-9674, E-ISSN 2001-6131, Vol. 3, no 15, p. 38-60Article in journal (Refereed)
    Abstract [sv]

    I artikeln lyfts resultat från ett pågående arbete fram, där en ny metod prövas. Syftet är att visa hur studier av lärarens didaktiska val kan bidra med kunskap om hur ett kroppsligt kunnande inom skolämnet teater på gymnasienivå utvecklas. Metoden om används är ett exempel på hur man kan studera lärarens didaktiska val och därigenom utveckla kunskap om innehållsliga aspekter av ämnet. Resultatet från studien, där interaktionsanalys har använts, pekar på hur lärares professionella omdöme delvis är inbegripet som del av en praxis. De slutsatser som dras avser att visa hur kunskap i ett estetiskt ämne kan visualiseras och artikuleras. Artikeln syftar till att problematisera och diskutera hur man kan prata om och i undervisningen hantera utvecklandet av ämnesspecifika förmågor.

  • 2054. Ahlstrand, Tuuli
    et al.
    Torittu, Annamari
    Elovaara, Heli
    Välimaa, Hannamari
    Pöllänen, Marja T.
    Kasvandik, Sergo
    Högbom, Martin
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Ihalin, Riikka
    Interactions between the Aggregatibacter actinomycetemcomitans secretin HofQ and host cytokines indicate a link between natural competence and interleukin-8 uptake2018In: Virulence, ISSN 2150-5594, E-ISSN 2150-5608, Vol. 9, no 1, p. 1205-1223Article in journal (Refereed)
    Abstract [en]

    Naturally competent bacteria acquire DNA from their surroundings to survive in nutrient-poor environments and incorporate DNA into their genomes as new genes for improved survival. The secretin HofQ from the oral pathogen Aggregatibacter actinomycetemcomitans has been associated with DNA uptake. Cytokine sequestering is a potential virulence mechanism in various bacteria and may modulate both host defense and bacterial physiology. The objective of this study was to elucidate a possible connection between natural competence and cytokine uptake in A. actinomycetemcomitans. The extramembranous domain of HofQ (emHofQ) was shown to interact with various cytokines, of which IL-8 exhibited the strongest interaction. The dissociation constant between emHofQ and IL-8 was 43nM in static settings and 2.4M in dynamic settings. The moderate binding affinity is consistent with the hypothesis that emHofQ recognizes cytokines before transporting them into the cells. The interaction site was identified via crosslinking and mutational analysis. By structural comparison, relateda type I KH domain with a similar interaction site was detected in the Neisseria meningitidis secretin PilQ, which has been shown to participate in IL-8 uptake. Deletion of hofQ from the A. actinomycetemcomitans genome decreased the overall biofilm formation of this organism, abolished the response to cytokines, i.e., decreased eDNA levels in the presence of cytokines, and increased the susceptibility of the biofilm to tested -lactams. Moreover, we showed that recombinant IL-8 interacted with DNA. These results can be used in further studies on the specific role of cytokine uptake in bacterial virulence without interfering with natural-competence-related DNA uptake.

  • 2055. Ahlström, A. P.
    et al.
    Anderson, B.
    Arenillas, M.
    Bajracharya, S.
    Baroni, C.
    Bidlake, W. R.
    Braun, L. N.
    Caceres, B.
    Casassa, G.
    Ceballos, J. L.
    Cobos, G.
    Davila, L. R.
    Delgado Granados, H.
    Demberel, O.
    Demuth, M. N.
    Espizua, L.
    Fischer, A.
    Fujita, K.
    Gadek, B.
    Ghazanfar, A.
    Hagen, J. O.
    Hoelzle, M.
    Holmlund, Per
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Karimi, N.
    Li, Z.
    Martinez De Pison, E.
    Pelto, M.
    Pitte, P.
    Popovnin, V. V.
    Portocarrero, C. A.
    Prinz, R.
    Ramirez, J.
    Rudell, A.
    Sangewar, C.
    Severskiy, I
    Sigurdsson, O.
    Soruco, A.
    Tielidze, L.
    Usubaliev, R.
    Van Ommen, T.
    Vincent, C.
    Yakovlev, A.
    Historically unprecedented global glacier decline in the early 21st century2015In: Journal of Glaciology, ISSN 0022-1430, E-ISSN 1727-5652, Vol. 61, no 228, p. 745-+Article in journal (Refereed)
    Abstract [en]

    Observations show that glaciers around the world are in retreat and losing mass. Internationally coordinated for over a century, glacier monitoring activities provide an unprecedented dataset of glacier observations from ground, air and space. Glacier studies generally select specific parts of these datasets to obtain optimal assessments of the mass-balance data relating to the impact that glaciers exercise on global sea-level fluctuations or on regional runoff. In this study we provide an overview and analysis of the main observational datasets compiled by the World Glacier Monitoring Service (WGMS). The dataset on glacier front variations (similar to 42 000 since 1600) delivers clear evidence that centennial glacier retreat is a global phenomenon. Intermittent readvance periods at regional and decadal scale are normally restricted to a subsample of glaciers and have not come close to achieving the maximum positions of the Little Ice Age (or Holocene). Glaciological and geodetic observations (similar to 5200 since 1850) show that the rates of early 21st-century mass loss are without precedent on a global scale, at least for the time period observed and probably also for recorded history, as indicated also in reconstructions from written and illustrated documents. This strong imbalance implies that glaciers in many regions will very likely suffer further ice loss, even if climate remains stable.

  • 2056. Ahlström, Christer
    et al.
    Anund, Anna
    Fors, Carina
    Åkerstedt, Torbjörn
    Stockholm University, Faculty of Social Sciences, Stress Research Institute. Karolinska Institute, Sweden.
    Effects of the road environment on the development of driver sleepiness in young male drivers2018In: Accident Analysis and Prevention, ISSN 0001-4575, E-ISSN 1879-2057, Vol. 112, p. 127-134Article in journal (Refereed)
    Abstract [en]

    Latent driver sleepiness may in some cases be masked by for example social interaction, stress and physical activity. This short-term modulation of sleepiness may also result from environmental factors, such as when driving in stimulating environments. The aim of this study is to compare two road environments and investigate how they affect driver sleepiness. Thirty young male drivers participated in a driving simulator experiment where they drove two scenarios: a rural environment with winding roads and low traffic density, and a suburban road with higher traffic density and a more built-up roadside environment. The driving task was essentially the same in both scenarios, i.e. to stay on the road, without much interaction with other road users. A 2 x 2 design, with the conditions rural versus suburban, and daytime (full sleep) versus night-time (sleep deprived), was used. The results show that there were only minor effects of the road environment on subjective and physiological indicators of sleepiness. In contrast, there was an increase in subjective sleepiness, longer blink durations and increased EEG alpha content, both due to time on task and to night-time driving. The two road environments differed both in terms of the demand on driver action and of visual load, and the results indicate that action demand is the more important of the two factors. The notion that driver fatigue should be countered in a more stimulating visual environment such as in the city is thus more likely due to increased task demand rather than to a richer visual scenery. This should be investigated in further studies.

  • 2057. Ahlström, Christer
    et al.
    Anund, Anna
    Fors, Carina
    Åkerstedt, Torbjörn
    Stockholm University, Faculty of Social Sciences, Stress Research Institute. Karolinska Institute, Sweden.
    The effect of daylight versus darkness on driver sleepiness: a driving simulator study2018In: Journal of Sleep Research, ISSN 0962-1105, E-ISSN 1365-2869, Vol. 27, no 3, article id e12642Article in journal (Refereed)
    Abstract [en]

    Driver sleepiness studies are often carried out with alert drivers during daytime and sleep-deprived drivers during night-time. This design results in a mixture of different factors (e.g. circadian effects, homeostatic effects, light conditions) that may confound the results. The aim of this study was to investigate the effect of light conditions on driver sleepiness. Thirty young male drivers (23.6 ± 1.7 years old) participated in a driving simulator experiment where they drove on a rural road. A 2 × 2 design was used with the conditions daylight versus darkness, and daytime (full sleep) versus night-time (sleep deprived). The results show that light condition had an independent effect on the sleepiness variables. The subjective sleepiness measured by Karolinska Sleepiness Scale was higher, lateral position more left-oriented, speed lower, electroencephalogram alpha and theta higher, and blink durations were longer during darkness. The number of line crossings did not change significantly with light condition. The day/night condition had profound effects on most sleepiness indicators while controlling for light condition. The number of line crossings was higher during night driving, Karolinska Sleepiness Scale was higher, blink durations were longer and speed was lower. There were no significant interactions, indicating that light conditions have an additive effect on sleepiness. In conclusion, Karolinska Sleepiness Scale and blink durations increase primarily with sleep deprivation, but also as an effect of darkness. Line crossings are mainly driven by the need for sleep and the reduced alertness at the circadian nadir. Lane position is, however, more determined by light conditions than by sleepiness.

  • 2058. Ahlström, Christer
    et al.
    Fors, Carina
    Anund, Anna
    Hallvig, David
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Video-based observer rated sleepiness versus self-reported subjective sleepiness in real road driving2015In: European Transport Research Review, ISSN 1867-0717, E-ISSN 1866-8887, Vol. 7, no 4, article id 38Article in journal (Refereed)
    Abstract [en]

    Purpose: Observer-rated sleepiness (ORS) based on video recordings of the driver's face is often used when analysing naturalistic driving data. The aim of this study is to investigate if ORS ratings agree with subjective self-reported sleepiness (SRS). Methods: Forty raters assessed 54 video-clips showing drivers with varying levels of sleepiness. The video-clips were recorded during a field experiment focusing on driver sleepiness using the same cameras that are typically used in large-scale field studies. The weak results prompted a second test. Ten human factors researchers made pairwise comparisons of videos showing the same four participants in an alert versus a very sleepy condition. The task was simply to select the video-clip where the driver was sleepy. Results: The overall average percentage of video segments where ORS and SRS matched was 41 % in Test 1. ORS 0 (alert) and ORS 2 (very sleepy) were easier to score than ORS 1 and it was slightly harder to rate night-time drives. Inter-rater agreement was low, with average Pearson's r correlations of 0.19 and Krippendorff's alpha of 0.15. In Test 2, the average Pearson's r correlations was 0.35 and Krippendorff's alpha was 0.62. The correspondence between ORS and SRS showed an agreement of 35 %. Conclusions: The results indicate that ORS ratings based on real road video recordings correspond poorly with SRS and have low inter-rater agreement. Further research is necessary in order to further evaluate the usefulness of ORS as a measure of sleepiness.

  • 2059. Ahlström, Christer
    et al.
    Nyström, Marcus
    Holmqvist, Kenneth
    Fors, Carina
    Sandberg, David
    Anund, Anna
    Kecklund, Göran
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Åkerstedt, Torbjörn
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Fit-for-duty test for estimation of drivers' sleepiness level: Eye movements improve the sleep/wake predictor2013In: Transportation Research Part C: Emerging Technologies, ISSN 0968-090X, E-ISSN 1879-2359, Vol. 26, p. 20-32Article in journal (Refereed)
    Abstract [en]

    Driver sleepiness contributes to a considerable proportion of road accidents, and a fit-for-duty test able to measure a driver’s sleepiness level might improve traffic safety. The aim of this study was to develop a fit-for-duty test based on eye movement measurements and on the sleep/wake predictor model (SWP, which predicts the sleepiness level) and evaluate the ability to predict severe sleepiness during real road driving. Twenty-four drivers participated in an experimental study which took place partly in the laboratory, where the fit-for-duty data were acquired, and partly on the road, where the drivers sleepiness was assessed. A series of four measurements were conducted over a 24-h period during different stages of sleepiness. Two separate analyses were performed; a variance analysis and a feature selection followed by classification analysis. In the first analysis it was found that the SWP and several eye movement features involving anti-saccades, pro-saccades, smooth pursuit, pupillometry and fixation stability varied significantly with different stages of sleep deprivation. In the second analysis, a feature set was determined based on floating forward selection. The correlation coefficient between a linear combination of the acquired features and subjective sleepiness (Karolinska sleepiness scale, KSS) was found to be R = 0.73 and the correct classification rate of drivers who reached high levels of sleepiness (KSS ⩾ 8) in the subsequent driving session was 82.4% (sensitivity = 80.0%, specificity = 84.2% and AUC = 0.86). Future improvements of a fit-for-duty test should focus on how to account for individual differences and situational/contextual factors in the test, and whether it is possible to maintain high sensitive/specificity with a shorter test that can be used in a real-life environment, e.g. on professional drivers.

  • 2060.
    Ahlström, Christian
    Stockholm University, Faculty of Humanities.
    Spår av hav, yxa och penna: historiska sjöolyckor i Östersjön avspeglade i marinarkeologiskt källmaterial1995Doctoral thesis, monograph (Other academic)
  • 2061.
    Ahlström, David
    et al.
    Stockholm University, Faculty of Social Sciences, School of Business.
    Luthman, Andreas
    Stockholm University, Faculty of Social Sciences, School of Business.
    En studie av likviditeten i SAS - aktien2003Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    I denna uppsats har författarna genomfört en kvalitativ studie i syfte att undersöka vilka orsaker som legat bakom den låga likviditeten i SAS-aktien. Studien har innefattat intervjuer med representanter från institutionella ägare och investerare. Av den empiriska undersökningen har det framkommit att det statliga ägandet och den låga free floaten främst bidragit till likviditetssituationen. Vidare har respondenterna angivit likviditeten i flygindustrin samt börsklimatet varit tongivande för likviditetsutvecklingen i SAS-aktien. Ytterligare en aspekt som försämrat förutsättningarna för likviditeten anges ha varit en alltför svåranalyserad och förhållandevis liten verksamhet. Det har således inte ansetts vara ekonomiskt försvarbart att analysera SAS-aktien i någon större omfattning. Detta har i sin tur bidragit till att aktien inte varit föremål för förvaltares och mäklares intresse i någon större utsträckning. Dessutom har värdeskapandet i SAS varit dåligt de senaste åren, varför vissa aktörer pekat på en viss uppgivenhet inför aktien som sådan. Analysen och slutsatsen av uppsatsen diskuterar vilka åtgärder som SAS kan tänkas vidta för att förbättra likviditeten på Stockholmsbörsen.

  • 2062.
    Ahlström, Elin
    Stockholm University, Faculty of Humanities, Department of English.
    How do influencers portray companies on Instagram?: A multimodal discourse analysis on sponsored updates on the social media network Instagram2017Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The present thesis approaches the newly developed phenomenon of Influencer Marketing, with the aim to investigate the structure of influencer’s sponsored posts on the social media network Instagram. As people continuously express their opinions and feelings on social networking sites, this thesis analyses the textual and multimodal aspects of 18 posts from six influencers of two companies, namely Daniel Wellington and Na-kd, from the perspective of stance to distinguish similarities, differences and patterns concerning the structure of the posts and what these might imply regarding how a sponsored update marketing a product is structured. The results indicate that a common structure of how sponsored updates are generally constructed exists, but that the way they structure their posts does not depend on which company they are presenting, but rather how influencers structure their posts in general. Hence, there are similarities that conform to the influencers marketing both companies, for instance that the texts have roughly the same length and similar composition- both regarding the textual and the multimodal aspects. In addition, one important finding was the need of pragmatic competence to fully interpret how the influencer expresses stance, evaluation and positioning in the sponsored updates. To conclude, as Influencer Marketing provide a new way of communicating, I hope that other researchers continue to investigate Influencer Marketing on social media to contribute to the field of linguistics further. 

  • 2063.
    Ahlström, Hanna
    Stockholm University, Faculty of Science, Stockholm Resilience Centre.
    Institutional structures and actor collaborations for the governance of global nitrogen and phosphorous cycles: investigating polycentric order2015Independent thesis Advanced level (degree of Master (Two Years)), 40 credits / 60 HE creditsStudent thesis
    Abstract [en]

    Despite an increased interest from the global change and resilience community, there is limited knowledge about the features and outcomes of polycentric governance. Moreover, there are few examples from the literature explaining transitions from lower to higher degrees of polycentric order. This seriously limits the explanatory power and application potential of the theory. The present study addresses this gap by investigating the global governance of nitrogen (N) and phosphorous (P) cycles. Those biophysical flows are two of the identified Earth-system processes in the “planetary boundaries” framework. This study explores governance challenges associated to these processes by analysing present institutional structures and actor collaborations. This is done by studying the network structures among all relevant multilateral agreements, EU (-level) Directives, and agreements on trade, combined with a more in-depth analysis of one global partnership initiative as a means to assess a possible emerging structure of polycentric order. The present study provides insights into how the current governance regimes in place for regulating the issues related to N and P flows look like, as well as issues and synergies of having a global partnership in place. The study suggests a global structure of polycentricity, which has the possibility to evolve into a better “match” with the dynamics of those biophysical flows through a larger governance context. 

  • 2064. Ahlström, Hanna
    et al.
    Cornell, Sarah E.
    Stockholm University, Faculty of Science, Stockholm Resilience Centre.
    Governance, polycentricity and the global nitrogen and phosphorus cycles2018In: Environmental Science and Policy, ISSN 1462-9011, E-ISSN 1873-6416, Vol. 79, p. 54-65Article in journal (Refereed)
    Abstract [en]

    Global change and governance scholars frequently highlight polycentricity as a feature of resilient governance, but both theoretical and empirical knowledge about features and outcomes of the concept are lacking at the global scale. Here we investigate the structural properties of governance of global nitrogen (N) and phosphorus (P) cycles, two processes in the 'planetary boundaries' framework. We have used a mixed-methods approach to institutional analysis, integrating polycentric theory with social network theory in environmental policy and legal studies. We include an actor collaboration case study, the Global Partnership on Nutrient Management (GPNM), to explore governance challenges associated with global N and P cycles. We set the scope for selection of relevant legal instruments using an overview of global N and P flows between Earth system 'components' (land, water, atmosphere, oceans, biosphere) and the major anthropogenic N and P perturbations. Our network analysis of citations of global N and P governance exposes the structural patterns of a loose network among the principal institutions and actors, in which legal instruments of the European Union serve as key cross-scale and cross-sectoral 'gateways'. We show that the current international regimes in place for regulating N- and P-related issues represent a gap in governance at the global level. In addition, we are able to show that the emergence of GPNM provides synergies in this context of insufficient governance. The GPNM can be viewed as a structure of polycentric governance as it involves deliberate attempts for mutual adjustments and self-organised action.

  • 2065.
    Ahlström, Jenny
    et al.
    Stockholm University, Faculty of Social Sciences, Department of Child and Youth Studies.
    Lesant, Anna
    Stockholm University, Faculty of Social Sciences, Department of Child and Youth Studies.
    ”Barnen är ju redan där, de är ju hur nyfikna och intresserade som helst”: IKT i förskolan2015Independent thesis Basic level (professional degree), 210 HE creditsStudent thesis
    Abstract [sv]

    Syftet med vår studie är att undersöka vilka faktorer som är avgörande när det gäller implementering av IKT i förskolan samt hur arbetet med IKT kan integreras på ett kreativt sätt i den pedagogiska verksamheten. För att försöka ta reda på detta har vi genomfört en kvalitativ studie där vi intervjuat medie/IKT-pedagoger för att kunna ta del av deras tankar och erfarenheter. Resultatet visar att ledning och chefer som satsar på och prioriterar IKT är en viktig aspekt. Att tid avsätts för regelbundna reflektionstillfällen är av mycket stor betydelse för att kunna utveckla arbetet med IKT, ett arbete som måste förstås som en ständigt pågående process. Medutforskande pedagoger med ett nyfiket och öppet förhållningssätt är en avgörande faktor för att IKT ska integreras på ett kreativt sätt i förskolans verksamhet. Studien visar även på vikten av att barn ges möjlighet att utveckla digital kompetens för att kunna vara delaktiga i ett digitalt samhälle.

  • 2066.
    Ahlström, Linda
    Stockholm University, Faculty of Social Sciences, Department of Special Education.
    Man bygger lösningar efter de barn man har: En studie om några pedagogers arbetssätt kring inkluderande undervisningssituationer.2010Independent thesis Advanced level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The aim with my study was to examine how some tachers interpret the term inclusion and how they implement it in their work. Information has been collected through focus interviews with sex teachers from two pedagogical teams at an elementary school in Stockholm. The mail questions regarded the teachers view and thoughts on inclusion and also eventual difficulties they saw by working with inclusion within the classroom. The study showed that there was a difference of opinion between the interviewed teachers on what including workway was. One of the pedagogical teams said that all the students should be in the classroom in order to feel included. The other team said that it was not the classroom but that students should feel included in the learning process. Many of the teachers felt that working with inclusion through learning and teaching meant that the students should feel they succeeded. Homework and lessons were adapted to the student’s individual needs. Teachers used different methods in working with inclusion in their lessons. The difficulties they seen in their work were to succeed in keeping all the students working and challenge them as far as possible. There were also difficulties finding balance between those students who needed help and those that were independent.   

  • 2067.
    Ahlström, Magnus
    et al.
    Stockholm University, Faculty of Social Sciences, School of Business.
    Lindén, Peter
    Stockholm University, Faculty of Social Sciences, School of Business.
    Telias Investor Relations utifrån ett relationsmarknadsföringsperspektiv2001Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Uppsatsen bedrivs som en fallstudie på Telia. I denna fallstudie undersöker vi hur Telia använder sig av relationsmarknadsföring i sin investor relations.

  • 2068.
    Ahlström, Margareta
    Stockholm University, Faculty of Social Sciences, Department of Psychology.
    Hörselskadade barn i kommunikation och samspel2000Doctoral thesis, monograph (Other academic)
    Abstract [en]

    The aim of this thesis was to study the communicative and social development of twelve hard of hearing children, between the ages of two and seven. The children were observed by videorecordings, during a two year period in natural settings in three different sign language preschools, where sign language and spoken Swedish was exposed to the children at a varying extent. The theoretical basis of this thesis is found in modem child development research emphasising the significance of early close relationships with adults and peers. In order to give a description of the cultural context, interviews were made with parents and staffmembers. A descriptive qualitative analysis of the non-verbal and verbal communication between the children and the staff-members was conducted in order to focus on patterns of interaction within the group of hard of hearing children and between hard of hearing and deaf children, as well as between the children and the staff-members. From the analysis, five different patterns of interaction emerged and will be presented as five case studies at an individual and at a group level. These two perspectives were necessary in order to understand the way the hard of hearing children communicated in different contexts. The adults attitudes towards play and language, manifested by the way in which they acted towards the children played a central part to the outcome of peer-peer and adult-child interactions. The research findings indicated that a multitude of circumstances influenced the development of communicative skills of the children. The use of a language that enabled them to understand and to be understood, a supportive communicative style of the adults, where focus was on the content and the quality of the interaction in combination with a positive attitude towards fantasy and role play seemed to promote the children’s well-being and communicative and social development, more than an adult-centred and directive communicative style where the two languages per se were in focus.

  • 2069.
    Ahlström, Mette
    Stockholm University, Faculty of Humanities, Department of Scandinavian Languages.
    Att jonglera med ord: Berättelser om språksituationen på en mångspråkig cirkusskola2012Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    I den här uppsatsen görs en kvalitativ samtalsanalytisk analys av sammanlagt åtta narrativer. Dessa är hämtade ur intervjuer med en lärare och en elev vid Cirkus Cirkörs dåvarande utbildning Cirkuspiloterna - en internationell utbildning där lärare och elever ofta inte hade ett gemensamt språk att mötas i. Syftet med analysen är att synliggöra likheter och skillnader mellan hur läraren och eleven berättar berättelser om händelser som har att göra med den språkliga situationen på skolan - vilken funktion berättelserna har i respektive intervju, samt vilka attityder till språksituationen som speglas i narrativerna. Analysen visar att läraren, till skillnad från eleven, verkar ha en färdig berättelserepertoar och att berättelserna fungerar som exempel i lärarens argumentation. För eleven verkar istället berättelserna utgöra en resurs att resonera sig fram till svar på intervjufrågorna, och elevens berättelser ger ett intryck av att födas i ögonblicket snarare än att vara en del av ett etablerat berättande. Både lärarens och elevens narrativ genomsyras av tydligt positiva attityder till språksituationen på skolan, men analysen visar en mer medveten och aktiv uppskattning från lärarens sida.

  • 2070.
    Ahlström, Stellan
    Stockholm College.
    Strindbergs erövring av Paris: Strindberg och Frankrike 1884-18951956Doctoral thesis, monograph (Other academic)
  • 2071.
    Ahlström Söderling, Ragnar
    Stockholm University, Faculty of Social Sciences, School of Business.
    Regionala företags förutsättningar för internationell konkurrenskraft: utvärdering av en undersökningsmetod2006Doctoral thesis, monograph (Other academic)
    Abstract [en]

    Kan man bedöma om företag med tillväxtpotential även har kompetens att ta tillvara den? Denna fundering ligger till grund för den studie som redovisas i den här avhandlingen.

    Syftet med studien är i första hand att utvärdera hur en ”Best Business Practice”- modell kan bidra till ökad förståelse, hos myndigheter och andra samhällsaktörer, för vilka befintliga företag i en region som kan ha förutsättningar att vara internationellt konkurrenskraftiga med avseende på de processutövanden och processresultat som föreligger i deras operativa verksamhet. Utvärderingen baseras på en kartläggning av tillverkande arbetsställen i Dalarnas län med minst 10 anställda som genomfördes 2002.

    Studien i Dalarna bekräftar undersökningsmodellens antagande om en relation mellan gott processutövande och bra processresultat. Analyser visar att företag med höga värden på såväl processutövande som processresultat (de Ledande företagen) har högre sannolikhet för att redovisa en hög och ökande marknadsandel, förbättrad produktivitet, ökande nettokassaflöde, god och förbättrad lönsamhet samt en högre avkastningsgrad än företag med låga värden på dessa parametrar (de Sladdande företagen). Studien indikerar även ett samband mellan tillväxt och processresultat då de flesta företagen med hög tillväxt redovisar höga värden på undersökningsmetodens indexet för processresultat samtidigt som de flesta företagen med negativ tillväxt har låga värden på detta index.

    De marknadsledande företagen i studien skiljer sig från övriga företag genom att oftare använda sig av benchmarking. I sina benchmarkingprocesser fokuserar de på ett bredare spann av jämförelsemått, jämför sig oftare med företag inom andra branscher såväl som andra länder samt lägger en större fokus på innovations- och verksamhetsmått.. De marknadsledande företagen är även mer innovativa, både vad gäller introduktion av nya produkter som av nya processer.

    Utvärderingen redovisar att undersökningsmetoden har en del tveksamheter men trots det ger möjlighet att skaffa en mängd information och kunskap om näringslivets status i en region. Den visar på vilka företag som har processer på plats för att kunna expandera och vilka som behöver ”se om sitt hus” för att ha möjlighet att fortsätta sin verksamhet.

    Det räcker dock inte med kunskap. Kunskapen behöver omsättas i handling. En fråga som avhandlingen leder fram till är vilka som kan och vill agera på denna typ av information?

  • 2072.
    Ahlström, Torbjörn
    Stockholm University, Faculty of Humanities, Osteology Unit.
    Landmark morphometrics and osteology1994Doctoral thesis, comprehensive summary (Other academic)
  • 2073.
    Ahlsén, Emelie
    et al.
    Stockholm University, The Stockholm Institute of Education.
    Lundh, Nathalie
    Stockholm University, The Stockholm Institute of Education.
    Teaching Writing in Theory and Practice: A Study of Ways of Working with Writing in the 9th Grade2008Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The main purpose of this study is to take a closer look at how teachers work with writing and to examine some theories on the teaching of writing. Five teachers in two schools are included in order to get an insight in teachers’ practical work with EFL writing. This has been done through classroom observations and interviews. The results show that all teachers seem to use aspects from several theories. The results also show that the teachers’ level of awareness of theories on teaching writing varies

  • 2074. Ahltorp, Magnus
    et al.
    Skeppstedt, Maria
    Stockholm University, Faculty of Social Sciences, Department of Computer and Systems Sciences.
    Dalianis, Hercules
    Stockholm University, Faculty of Social Sciences, Department of Computer and Systems Sciences.
    Kvist, Maria
    Stockholm University, Faculty of Social Sciences, Department of Computer and Systems Sciences.
    Using text prediction for facilitating input and improving readability of clinical text2013In: MedInfo 2013: Proceedings of the 14th World Congress on Medical and Health Informatics / [ed] Christoph Ulrich Lehmann, Elske Ammenwerth, Christian Nøhr, IOS Press, 2013, p. 1149-1149Conference paper (Refereed)
    Abstract [en]

    Text prediction has the potential for facilitating and speeding up the documentation work within health care, making it possible for health personnel to allocate less time to documentation and more time to patient care. It also offers a way to produce clinical text with fewer misspellings and abbreviations, increasing readability. We have explored how text prediction can be used for input of clinical text, and how the specific challenges of text prediction in this domain can be addressed. A text prediction prototype was constructed using data from a medical journal and from medical terminologies. This prototype achieved keystroke savings of 26% when evaluated on texts mimicking authentic clinical text. The results are encouraging, indicating that there are feasible methods for text prediction in the clinical domain.

  • 2075. Ahltorp, Magnus
    et al.
    Skeppstedt, Maria
    Kitajima, Shiho
    Henriksson, Aron
    Stockholm University, Faculty of Social Sciences, Department of Computer and Systems Sciences.
    Rzepka, Rafal
    Araki, Kenji
    Expansion of medical vocabularies using distributional semantics on Japanese patient blogs2016In: Journal of Biomedical Semantics, ISSN 2041-1480, E-ISSN 2041-1480, Vol. 7, article id 58Article in journal (Refereed)
    Abstract [en]

    Background: Research on medical vocabulary expansion from large corpora has primarily been conducted using text written in English or similar languages, due to a limited availability of large biomedical corpora in most languages. Medical vocabularies are, however, essential also for text mining from corpora written in other languages than English and belonging to a variety of medical genres. The aim of this study was therefore to evaluate medical vocabulary expansion using a corpus very different from those previously used, in terms of grammar and orthographics, as well as in terms of text genre. This was carried out by applying a method based on distributional semantics to the task of extracting medical vocabulary terms from a large corpus of Japanese patient blogs. Methods: Distributional properties of terms were modelled with random indexing, followed by agglomerative hierarchical clustering of 3x100 seed terms from existing vocabularies, belonging to three semantic categories: Medical Finding, Pharmaceutical Drug and Body Part. By automatically extracting unknown terms close to the centroids of the created clusters, candidates for new terms to include in the vocabulary were suggested. The method was evaluated for its ability to retrieve the remaining n terms in existing medical vocabularies. Results: Removing case particles and using a context window size of 1 + 1 was a successful strategy for Medical Finding and Pharmaceutical Drug, while retaining case particles and using a window size of 8 + 8 was better for Body Part. For a 10n long candidate list, the use of different cluster sizes affected the result for Pharmaceutical Drug, while the effect was only marginal for the other two categories. For a list of top n candidates for Body Part, however, clusters with a size of up to two terms were slightly more useful than larger clusters. For Pharmaceutical Drug, the best settings resulted in a recall of 25 % for a candidate list of top n terms and a recall of 68 % for top 10n. For a candidate list of top 10n candidates, the second best results were obtained for Medical Finding: a recall of 58 %, compared to 46 % for Body Part. Only taking the top n candidates into account, however, resulted in a recall of 23 % for Body Part, compared to 16 % for Medical Finding. Conclusions: Different settings for corpus pre-processing, window sizes and cluster sizes were suitable for different semantic categories and for different lengths of candidate lists, showing the need to adapt parameters, not only to the language and text genre used, but also to the semantic category for which the vocabulary is to be expanded. The results show, however, that the investigated choices for pre-processing and parameter settings were successful, and that a Japanese blog corpus, which in many ways differs from those used in previous studies, can be a useful resource for medical vocabulary expansion.

  • 2076. Ahltorp, Magnus
    et al.
    Skeppstedt, Maria
    Stockholm University, Faculty of Social Sciences, Department of Computer and Systems Sciences.
    Kitajima, Shiho
    Rzepka, Rafal
    Araki, Kenji
    Medical vocabulary mining using distributional semantics on Japanese patient blogs2014In: Proceedings of the 6th International Symposium on Semantic Mining in Biomedicine, 2014, p. 57-62Conference paper (Refereed)
    Abstract [en]

    Random indexing has previously been successfully used for medical vocabulary expansion for Germanic languages. In this study, we used this approach to ex- tract medical terms from a Japanese pa- tient blog corpus. The corpus was seg- mented into semantic units by a semantic role labeller, and different pre-processing and parameter settings were then evalu- ated. The evaluation showed that simi- lar settings are suitable for Japanese as for previously explored Germanic languages, and that distributional semantics is equally useful for semi-automatic expansion of Japanese medical vocabularies as for med- ical vocabularies in Germanic languages.

  • 2077.
    Ahlvar, Susanne Elisabeth
    et al.
    Stockholm University, Faculty of Social Sciences, School of Business.
    Holtsjö, Sara
    Stockholm University, Faculty of Social Sciences, School of Business.
    Belöningssystem: Styrverktyg för ledningen?2003Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    För att nå verksamhetens mål styr många företagsledare sina företag genom så kallade styrverktyg. Styrverktyg är hjälpmedel för att kunna styra företag mot deras ekonomiska mål. Exempel på styrverktyg är bland andra budgetering, internredovisning och belöningssystem. Belöningssystem kan användas i den operativa styrningen. Syftet med belöningssystem är att medarbetarna skall motiveras att prestera maximalt för att säkerställa effektiviteten i företaget.

  • 2078.
    Ahlvik Doverhem, Rebecka
    Stockholm University, Faculty of Law, Department of Law.
    Förhållandet mellan förskott på arv och laglott: en belysning av rättsläget och dess tillämpningsproblem2016Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
  • 2079. Ahlvik, P
    et al.
    Karlsson, Hans
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Westerholm, Roger
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Åsman, P
    Exhaust emissions from flexi-fuel light-duty passenger cars fuelled by petrol (E5) and bioethanol (E70, E85) tested at ambient temperatures of +22°C and -7°C: Part 1:Regulated and particulate emissions.2008In: Proceedings of the17:th International Symposium on Alcohol Fuels, 2008Conference paper (Other academic)
  • 2080.
    Ahlzén, Björn
    Stockholm University, Faculty of Social Sciences, Department of Sociology.
    Att bryta mot samhällsnormer: En kvantitativ studie om hög alkoholkonsumtion och narkotikabruk2011Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Synen på hög alkoholkonsumtion respektive narkotikabruk skiljer sig mellan olika samhällen, och i Sverige har vi en tradition av att problematisera dessa beteenden i högre grad än i många andra länder. Dessutom ses narkotikabruk som en mer klandervärd handling än hög alkoholkonsumtion. Med dessa socialt konstruerade skillnader i åtanke fokuserar uppsatsen på vad om ligger bakom dessa beteenden och om liknande faktorer kan förklara dem. Uppsatsens syfte är med andra ord att undersöka huruvida liknande bakgrundsvariabler kan förklara hög alkoholkonsumtion och narkotikabruk bland individer i Sverige. För att förstå varför olika sociala regler och normer råder i olika samhällen används Howard Beckers klassiska stämplingsteori. Tidigare forskning visar att i synnerhet kön och ålder är viktiga variabler för att förklara skillnader i alkoholkonsumtion och narkotikabruk, men även inkomst och familjekonstellation tycks spela en roll. För narkotikabruk verkar även sysselsättning och möjligen också utbildning ha betydelse. Studien är kvantitativ och bygger på ett datamaterial bestående av 5 469 respondenter. Analyserna genomfördes med logistisk regressionsanalys. Resultaten visade att det endast finns signifikanta samband mellan hög alkoholkonsumtion och variablerna kön och ålder, då män och yngre i högre grad riskerar att vara högkonsumenter av alkohol. För narkotikabruk var de signifikanta sambanden fler, förutom kön och ålder hade även sysselsättning, inkomst och huruvida man bor med en partner eller inte en signifikant effekt för förklaringen av vilka som brukar narkotika. Starkast var dock, även här, sambanden för kön och ålder som hade samma riktning som för hög alkoholkonsumtion. Detta skulle kunna tyda på att män och yngre personer inte fördöms lika hårt som övriga grupper när de högkonsumerar alkohol respektive brukar narkotika. Då narkotikabruk visade sig vara mycket ovanligt skulle studien gynnas av ett större datamaterial då säkrare slutsatser skulle kunna dras.

  • 2081.
    Ahlzén, Maja-Stina
    Stockholm University, Faculty of Social Sciences, Department of Social Work.
    Vägen till hemlöshet: en studie av nio livshistorier2005Independent thesis Advanced level (degree of Master (One Year)), 20 credits / 30 HE creditsStudent thesis
    Abstract [sv]

    Syftet med studien är att öka förståelsen för den process som leder till hemlöshet. Utifrån intervjuer med nio personer belyses de hemlöshetsgenererande processer som för var och en av dem lett till att de förlorat sin bostad och inte kunnat få någon ny.

    Intervjuerna har analyserats med hjälp av fattigdomsspiralen. Analysen visar hur de intervjuades resurser successivt har utarmats när de passerat genom olika stadier av kriser och svårigheter. Successivt har de förlorat makten över sina liv och för några av dem har detta lett till permanent fattigdom och utslagning. Genom att använda ett krisperspektiv kan utslagningsprocessen göras tydlig.

    Studien visar också hur socialtjänsten för flera av de intervjuade medverkat i utslagningsprocessen. Samtliga intervjupersoner har varit med om svåra trauman som de inte fått möjlighet att bearbeta. I mötet med socialtjänsten har deras trauman inte uppmärksammats och insatserna har i stor utsträckning inte varit individuellt anpassade.

    Även ett historiskt perspektiv kan tydliggöra utslagningsprocessen. Litteraturen visar hur attityderna gentemot fattiga och hemlösa har växlat genom historien.Till stora delar kan dagens sociallagstiftning härledas till medeltiden. Samtliga intervjupersoner har mött regler och förordningar vars underliggande attityder har sina rötter långt tillbaka i tiden.

    En viktig slutsats av studien är att socialtjänsten och andra berörda myndigheter bör sträva efter att i mycket större utsträckning än i dag ge varje hemlös ett individuellt bemötande. Åtgärder bör anpassas efter den hemlöses uppfattning om sina behov och inte efter myndighetens åtgärdsrepertoar.

  • 2082.
    Ahlén, Anton
    Stockholm University, Faculty of Social Sciences, Department of Political Science.
    Unconditional Conditions: A Study of How Civic Integration Policies Affect Migration Flows in Europe2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In the last decade, there has been a diffusion of civic integration policies in Europe, which

    requires immigrants by certain category of entry to accomplish integration tests for

    acquisition of residence. Despite a flurry of literature based on civic integration policies,

    attention drawn to the implication of these policies has been quite rare. This thesis examines

    how civic integration strategies associate with immigration, and tests if civic integration

    policies are connected to variations of immigration by certain category of entry. I argue in

    this thesis that the conditional factor in civic integration policies creates a barrier for affected

    migrants and their possibility to gain long term residence in the host country. Based on

    theories of immigrant integration that relate civic integration to the backlash against

    multiculturalism in Europe, the thesis emphasize a reasoning in which the push for internal

    inclusion seems to be associated with excluding implications. The result presented here

    shows that there are connections between the extension of civic integration policies and

    reduced family and labour immigration between 2004 and 2011. The connection between the

    variables can however not be discerned from other integration requirements. The main

    concern is the lack of harmonized data, which obstructs the possibility to test for causality

    and to draw generalizing conclusions. However, the thesis reveals noteworthy correlations

    between the concepts, which contribute to the research field by connecting civic integration

    to immigration and by showing what implications civic integration policies may result in.

  • 2083.
    Ahlén, Barbro
    et al.
    Stockholm University, Faculty of Social Sciences, Department of Education.
    Ekström, Anna
    Stockholm University, Faculty of Social Sciences, Department of Education.
    Samtalets dilemma: Vägledning som instrument vid sjukfrånvaro2009Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Counselling is one of the most commonly utilized tools in the work place. The purpose of this paper is to explore how four employers utilize early counselling sessions related to absences due to illness. A qualitative research method has been used and four human resource managers have been interviewed. The research questions have been divided into three categories: the counselling structure, the counselling model and the counselling dilemmas. The interviews have been transcribed and processed through these three categories. The results show that most employers are positive regarding conducting initial counselling sessions related to work absences. The experience of the session can vary depending on one’s role in the counselling session. Counselling sessions related to short term work absences are impacted by labour legislation, changes in the workplace, the company culture, and the amount of power held by the person who conducts the counselling session. One of the conclusions of this study is that it is difficult to combine initial counselling sessions regarding work absences with career counselling 

  • 2084.
    Ahlén, Emil
    et al.
    Stockholm University, Faculty of Social Sciences, Department of Social Work.
    Lundberg, Linn
    Stockholm University, Faculty of Social Sciences, Department of Social Work.
    Konstruktioner av en sexköpare: en diskursteoretisk analys av offentliga dokument2017Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The purpose of this study is to present dominant discourses of sex buyers in public documents published before and after the implementation of the Swedish sex buyer law; making the purchase but not the sale of sexual services illegal. The purpose is further to examine what consequences these discourses might have on social work with sex buyers. We also aim to illustrate how language, gender, sexuality and power can be understood in the reading of the empirical material stretching from 1981 to 2016. With a discourse theoretical approach drawn from Laclau and Mouffe (2008 [1985]), five prominent discourses are identified; the average man, the homosexual man, the woman as a sex buyer, the man with the problematic sexuality and the sex buyer in need of help. The main findings are that processes of conflict among the discourses outlines a social problem where discourses that don’t include the heterosexual man as a sex buyer are subdued. Gender and sexuality in general and male heterosexual sexuality in particular is performed. As demands on a stricter legislation is propositioned we identified a linguistic offset; from descriptive graphic characteristics of the sex buyer to a depersonalization focusing on the action rather than the actor. 

  • 2085.
    Ahlén, Niklas
    Stockholm University.
    Carbothermal synthesis of transition metal carbide and carbonitride whiskers via a Vapour-Liquid-Solid (VLS) growth mechanism1999Doctoral thesis, monograph (Other academic)
    Abstract [en]

    A route for the synthesis of TiC, TiCyN1-y, TaxTi1-xC and TaxTi1-xCyN1-y whiskers via a carbothermal Vapour-Liquid-Solid (VLS) growth mechanism, yielding 70-90 vol.% whiskers, has been established. The whiskers were uniform in diameter (0.3-0.6mm), and had a length of about 10-30mm. The starting materials consisted of TiO2 and/or Ta2O5, C, a catalyst metal (Ni or Fe) and NaCl. Carbon was added to reduce the oxides, and NaCl to provide chlorine in the formation of TiClx(g) and TaOxCly(g) species. The overall chemical reaction is a straightforward carbothermal reduction process. The optimum synthesis temperature was found to be 1250°C for TiCyN1-y, TaxTi1-xC and TaxTi1-xCyN1-y whisker, and 1400°C for TiC. The growth direction of the whiskers was found to be <100> for TaC and TaxTi1-xC and either <100> or <111> for TiC. Nitridation of TiC whiskers yielded TiCyN1-y whiskers with morphology and chemical composition different from those obtained by the carbothermal VLS growth mechanism. From oxidation studies it was found that TiC had the lowest oxidation resistance (onset temperature Ton=390°C) and that TaC had the highest (Ton=550°C). The oxidation onset temperature was found to increase with increasing x-value for both TaxTi1-xC and TaxTi1-xCyN1-y whiskers. Microscopy studies (SEM and TEM) showed that whiskers with a native diameter exceeding 0.3 mm split into two halves along their length when oxidised. It was found that the TiO2 particle size of oxidised TaxTi1-xC whiskers are markedly smaller than that obtained from oxidation of TiC whiskers, whereas the Ta2O5 particle size was the same as that observed for oxidised TaC whiskers.

  • 2086.
    Ahlénius, Emily
    Stockholm University, Faculty of Social Sciences, Department of Criminology.
    A Qualitative Analysis of the JudicialAspects of Child-Sex Tourism inThailand2010Independent thesis Basic level (degree of Bachelor), 15 credits / 22,5 HE creditsStudent thesis
    Abstract [en]

    Every year Thailand is invaded by tourists seeking the sun and white beautiful beaches. Most of them come for the inexpensive travel and lodging, good food and kind inviting people. For some of them the purpose of visit is somewhat different: every year there are people travelling to Thailand with the purpose to sexually exploit children. The world wide globalisation has contributed to a massive growth in tourism which has brought an economical growth to the country. This in turn has had some negative effects, where the poor rural areas are largely affected by inequality and the dream of a better lifestyle. Economical disadvantage, lack of education and the absence of capable guardians affect children’s vulnerability and make them an easy target for child-sex tourism. I argue that potential child-sex tourists travel to Thailand due to a perception of the prevalence of easy targets affected by people in a society that is not always aware of what is happening around them as well as due to a common perception that Thailand has a weak legal system. Based on this assumption and with the theoretical basis of routine activity and rational choice I research if there is a reason to believe that the legal system is corrupt. I believe that a combination of the three elements provided routine activity as well as analysing a phenomenon through rational choice can open up to answers of why perpetrators chose Thailand as their child-sex vacation hot-spot. To address the aim of my study I conducted six semi-structured interviews with people working in Bangkok, Thailand. From these interviews I first explain the process leading to the prosecution of Swedish child-sex tourists in Thailand and, second, uncover and examine potential difficulties in this process. In the result of this study a few of the answers differ substantially from previous studies as well as some of the interviewees sharing controversial opinions. The results of the conducted interviews show three identifiable weaknesses that play a large part in the problems of the judicial process. These three are: education, bail and cooperation between authorities.

  • 2087. Ahmad, Anees
    et al.
    Scarassati, Paulo
    Jalalian, Nazli
    Stockholm University, Faculty of Science, Department of Organic Chemistry. Universidade de São Paulo, Brazil.
    Olofsson, Berit
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Silva, Luiz F., Jr.
    Oxidative rearrangement of alkenes using in situ generated hypervalent iodine(III)2013In: Tetrahedron Letters, ISSN 0040-4039, E-ISSN 1359-8562, Vol. 54, no 43, p. 5818-5820Article in journal (Refereed)
    Abstract [en]

    A novel protocol for the oxidative rearrangement of alkenes using in situ generated hypervalent iodine(III) was developed. This approach uses inexpensive, readily available, and stable chemicals (PhI, mCPBA, and TsOH) giving rearrangement products in yields comparable to those obtained using the more expensive commercially available [hydroxy(tosyloxy)iodo]benzene [HTIB or Koser's reagent]. Additionally, an alternative protocol for the synthesis of 1-methyl-2-tetralone through the one-step epoxidation/rearrangement of 4-methyl-1,2-dihydronaphthalene using mCPBA and TsOH was developed.

  • 2088.
    Ahmad, Farhan
    Stockholm University, Faculty of Social Sciences, School of Business.
    Knowledge Transfer: Mechanism Selection Criteria2009Independent thesis Advanced level (degree of Master (Two Years)), 30 credits / 45 HE creditsStudent thesis
    Abstract [en]

    Knowledge transfer is one of the dominant topics in the organizational research today. This study criticizes the focus of the researchers to use the nature of knowledge as criteria to select a knowledge transfer mechanism. Consideration of this only criterion has led us to ignore the other relevant and important factors which could be very useful for selecting an appropriate knowledge transfer mechanism. On the basis of the fact that there is a high failure rate of the knowledge transfer mechanisms in the organizations, author tried to explore the effective factors in the selection of knowledge transfer mechanism because researchers believe that selection is the area which needs consideration for successful knowledge transfer. For this purpose two mechanisms i.e. expatriation and training were studied in three organizations. Interviews were used to find the primary information in the study. Findings imply that four factors geographic location, preconception of success, image development and size and age of the organization has dominant effect on the selection of knowledge transfer mechanism. This study tries to shift the focus of the research from consideration of more theoretical aspects like nature of knowledge to more practical ones like found in the study.

  • 2089.
    Ahmad, Farhan
    Stockholm University, Faculty of Social Sciences, Department of Sociology.
    Male immigrants’ fertility in Spain2011Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Declining fertility in developed countries along with rising number of immigrants and different fertility behavior exhibited by the immigrants make the immigrants’ fertility an interesting topic in field of demography. However most of the studies on immigrants’ fertility consider the female immigrants as their subject on the assumption that they represent the immigrants’ fertility. This study took another perspective and tries to study male immigrants’ fertility. Spanish Immigrants’ Survey 2007 was used to see how the different migration related factors affect the male immigrants’ fertility. Poisson regression was applied on a sample of 3797 childless males who are 16 or older. This study found tentative support to selection hypothesis but no clear support to adaptation hypothesis on male fertility behaviors. There exist differences in the fertility between male immigrants from different regions. Effect of education, number of parent’s siblings and mother language on male immigrants’ fertility was also analyzed.

  • 2090. Ahmad, Fouad
    et al.
    Ibrahim, Maha
    El-Esnawy, N
    Fors, Uno
    Stockholm University, Faculty of Social Sciences, Department of Computer and Systems Sciences.
    An e-Learning Faculty Development Course with Formative Assessment2010In: 16th Annual Sloan Consortium International Conference on Online Learning, 2010Conference paper (Other academic)
    Abstract [en]

    An e-Learning faculty development course has been developed and taught in Egypt for the past five years. The course adopts Formative Assessment (FA) techniques to enhance participants' learning. The additional FA effort for collecting and analyzing data as well as adjusting teaching is worth investing to accommodate gaps in learning.

  • 2091. Ahmad, Nawaz
    et al.
    Wörman, Anders
    Sanchez-Vila, Xavier
    Jarsjö, Jerker
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Bottacin-Busolin, Andrea
    Hellevang, Helge
    Injection of CO2-saturated brine in geological reservoir: A way to enhanced storage safety2016In: International Journal of Greenhouse Gas Control, ISSN 1750-5836, E-ISSN 1878-0148, Vol. 54, p. 129-144Article in journal (Refereed)
    Abstract [en]

    Injection of free-phase supercritical CO2 into deep geological reservoirs is associated with risk of considerable return flows towards the land surface due to the buoyancy of CO2, which is lighter than the resident brine in the reservoir. Such upward movements can be avoided if CO2 is injected in the dissolved phase (CO2aq). In this work, injection of CO2-saturated brine in a subsurface carbonate reservoir was modelled. Physical and geochemical interactions of injected low-pH CO2-saturated brine with the carbonate minerals (calcite, dolomite and siderite) were investigated in the reactive transport modelling. CO2-saturated brine, being low in pH, showed high reactivity with the reservoir minerals, resulting in a significant mineral dissolution and CO2 conversion in reactions. Over the injection period of 10yr, up to 16% of the injected CO2 was found consumed in geochemical reactions. Sorption included in the transport analysis resulted in additional quantities of CO2 mass stored. However, for the considered carbonate minerals, the consumption of injected CO2aq was found mainly in the form of ionic trapping.

  • 2092.
    Ahmad, Nina Sna
    Stockholm University, Faculty of Law, Department of Law.
    Privatkopieringsersättning för molntjänster: exemplarframställning av upphovsrättskyddade verk i molnbaserade lagringstjänster och fråga om privatkopieringsersättning2015Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
  • 2093. Ahmad, Shabbir
    et al.
    Thulasingam, Madhuranayaki
    Palombo, Isolde
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Daley, Daniel O.
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Johnson, Kenneth A.
    Morgenstern, Ralf
    Haeggström, Jesper Z.
    Rinaldo-Matthis, Agnes
    Trimeric microsomal glutathione transferase 2 displays one third of the sites reactivity2015In: Biochimica et Biophysica Acta - Proteins and Proteomics, ISSN 1570-9639, E-ISSN 1878-1454, Vol. 1854, no 10, p. 1365-1371Article in journal (Refereed)
    Abstract [en]

    Human microsomal glutathione transferase 2 (MGST2) is a trimeric integral membrane protein that belongs to the membrane-associated proteins in eicosanoid and glutathione metabolism (MAPEG) family. The mammalian MAPEG family consists of six members where four have been structurally determined. MGST2 activates glutathione to form a thiolate that is crucial for GSH peroxidase activity and GSH conjugation reactions with electrophilic substrates, such as 1-chloro-2,4-dinitrobenzene (CDNB). Several studies have shown that MGST2 is able to catalyze a GSH conjugation reaction with the epoxide LTA(4) forming the pro-inflammatory LTC4. Unlike its closest homologue leukotriene C-4 synthase (LTC4S), MGST2 appears to activate its substrate GSH using only one of the three potential active sites [Ahmad S, et al. (2013) Biochemistry. 52, 1755-1764]. In order to demonstrate and detail the mechanism of one-third of the sites reactivity of MGST2, we have determined the enzyme oligomeric state, by Blue native PAGE and Differential Scanning Calorimetry, as well as the stoichiometty of substrate and substrate analog inhibitor binding to MGST2, using equilibrium dialysis and Isothermal Titration Calorimetry, respectively. Global simulations were used to fit kinetic data to determine the catalytic mechanism of MGST2 with GSH and CDNB (1-chloro-2,4-dinitrobenzene) as substrates. The best fit was observed with 1/3 of the sites catalysis as compared with a simulation where all three sites were active. In contrast to LTC4S, MGST2 displays a 1/3 the sites reactivity, a mechanism shared with the more distant family member MGST1 and recently suggested also for microsomal prostaglandin E synthase-1.

  • 2094. Ahmad, Waqas
    et al.
    Fatima, Aamira
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Awan, Usman Khalid
    Anwar, Arif
    Analysis of long term meteorological trends in the middle and lower Indus Basin of Pakistan-A non-parametric statistical approach2014In: Global and Planetary Change, ISSN 0921-8181, E-ISSN 1872-6364, Vol. 122, p. 282-291Article in journal (Refereed)
    Abstract [en]

    The Indus basin of Pakistan is vulnerable to climate change which would directly affect the livelihoods of poor people engaged in irrigated agriculture. The situation could be worse in middle and lower part of this basin which occupies 90% of the irrigated area. The objective of this research is to analyze the long term meteorological trends in the middle and lower parts of Indus basin of Pakistan. We used monthly data from 1971 to 2010 and applied non-parametric seasonal Kendal test for trend detection in combination with seasonal Kendall slope estimator to quantify the magnitude of trends. The meteorological parameters considered were mean maximum and mean minimum air temperature, and rainfall from 12 meteorological stations located in the study region. We examined the reliability and spatial integrity of data by mass-curve analysis and spatial correlation matrices, respectively. Analysis was performed for four seasons (spring-March to May, summer-June to August-fall-September to November and winter-December to February). The results show that max. temperature has an average increasing trend of magnitude +0.16, +0.03, 0.0 and +0.04 degrees C/decade during all the four seasons, respectively. The average trend of min. temperature during the four seasons also increases with magnitude of +0.29, +0.12, +0.36 and +0.36 degrees C/decade, respectively. Persistence of the increasing trend is more pronounced in the min. temperature as compared to the max. temperature on annual basis. Analysis of rainfall data has not shown any noteworthy trend during winter, fall and on annual basis. However during spring and summer season, the rainfall trends vary from -1.15 to +0.93 and -3.86 to +2.46 mm/decade, respectively. It is further revealed that rainfall trends during all seasons are statistically non-significant. Overall the study area is under a significant warming trend with no changes in rainfall.

  • 2095.
    Ahmadi, Hamid
    et al.
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Bolinius, Dämien Johann
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Jahnke, Annika
    MacLeod, Matthew
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Mass transfer of hydrophobic organic chemicals between siliconesheets and through plant leaves and low-density polyethylene2016In: Chemosphere, ISSN 0045-6535, E-ISSN 1879-1298, Vol. 164, p. 683-690Article in journal (Refereed)
    Abstract [en]

    Plant leaves play an important role in the fate of hydrophobic organic contaminants (HOCs) in theenvironment. Yet much remains unknown about the permeability of leaves by HOCs. In this pilot studywe measured (i) the kinetics of mass transfer of three polycyclic aromatic hydrocarbons (PAHs) and sixpolychlorinated biphenyls between a spiked and an unspiked sheet of polydimethylsiloxane (PDMS) indirect contact with each other for 24 h and (ii) kinetics of mass transfer of two PAHs through leaves andlow-density polyethylene (LDPE) in a passive dosing experiment by inserting these matrices between thetwo sheets of PDMS for 48 h. The kinetics of mass transfer of fluoranthene between PDMS sheets in directcontact were a factor of 12 slower than those reported in the literature. The kinetics of mass transfer offluorene and phenanthrene through leaves were within the range of those previously reported for 2,4-dichlorophenoxyacetic acid through isolated cuticles. Our results provide a proof-of-concept demon-stration that the passive dosing method applied in this study can be used to measure the mass transfercoefficients of organic chemicals through leaves. Key recommendations for future experiments are toload the PDMS at the highest feasible concentrations to avoid working at analyte levels close to the limitof detection, to keep the leaves moist and to minimize potential pathways for contamination of the PDMSsheets by exposure to laboratory air.

  • 2096. Ahmadi, M.
    et al.
    Alves, B. X. R.
    Baker, C. J. .
    Bertsche, W.
    Butler, E.
    Capra, A.
    Carruth, C.
    Cesar, C. L.
    Charlton, M.
    Cohen, S.
    Collister, R.
    Eriksson, S.
    Evans, A.
    Evetts, N.
    Fajans, J.
    Friesen, T.
    Fujiwara, M. C.
    Gill, D. R.
    Gutierrez, A.
    Hangst, J. S.
    Hardy, W. N.
    Hayden, M. E.
    Isaac, C. A.
    Ishida, A.
    Ohnson, M. A. J.
    Ones, S. A. J.
    Jonsell, Svante
    Stockholm University, Faculty of Science, Department of Physics.
    Kurchaninov, L.
    Madsen, N.
    Mathers, M.
    Maxwell, D.
    McKenna, J. T. K.
    Menary, S.
    Michan, J. M.
    Momose, T.
    Munich, J. J. .
    Nolan, P.
    Olchanski, K.
    Olin, A.
    Pusa, P.
    Rasmussen, C. O.
    Robicheaux, F.
    Sacramento, R. L.
    Sameed, M.
    Sarid, E.
    Silveira, D. M.
    Stracka, S.
    Stutter, G.
    So, C.
    Tharp, T. D.
    Thompson, J. E.
    Thompson, R. I.
    van der Werf, D. P.
    Wurtele, J. S.
    Observation of the 1S-2S transition in trapped antihydrogen2017In: Nature, ISSN 0028-0836, E-ISSN 1476-4687, Vol. 541, no 7638, p. 506-510Article in journal (Refereed)
    Abstract [en]

    The spectrum of the hydrogen atom has played a central part in fundamental physics over the past 200 years. Historical examples of its importance include the wavelength measurements of absorption lines in the solar spectrum by Fraunhofer, the identification of transition lines by Balmer, Lyman and others, the empirical description of allowed wavelengths by Rydberg, the quantum model of Bohr, the capability of quantum electrodynamics to precisely predict transition frequencies, and modern measurements of the 1S-2S transition by Hansch1 to a precision of a few parts in 10(15). Recent technological advances have allowed us to focus on antihydrogen-the antimatter equivalent of hydrogen(2-4). The Standard Model predicts that there should have been equal amounts of matter and antimatter in the primordial Universe after the Big Bang, but today's Universe is observed to consist almost entirely of ordinary matter. This motivates the study of antimatter, to see if there is a small asymmetry in the laws of physics that govern the two types of matter. In particular, the CPT (charge conjugation, parity reversal and time reversal) theorem, a cornerstone of the Standard Model, requires that hydrogen and antihydrogen have the same spectrum. Here we report the observation of the 1S-2S transition in magnetically trapped atoms of antihydrogen. We determine that the frequency of the transition, which is driven by two photons from a laser at 243 nanometres, is consistent with that expected for hydrogen in the same environment. This laser excitation of a quantum state of an atom of antimatter represents the most precise measurement performed on an anti-atom. Our result is consistent with CPT invariance at a relative precision of about 2 x 10(-10).

  • 2097. Ahmadi, M.
    et al.
    Alves, B. X. R.
    Baker, C. J.
    Bertsche, W.
    Butler, E.
    Capra, A.
    Carruth, C.
    Cesar, C. L.
    Charlton, M.
    Cohen, S.
    Collister, R.
    Eriksson, S.
    Evans, A.
    Evetts, N.
    Fajans, J.
    Friesen, T.
    Fujiwara, M. C.
    Gill, D. R.
    Gutierrez, A.
    Hangst, J. S.
    Hardy, W. N.
    Hayden, M. E.
    Isaac, C. A.
    Ishida, A.
    Johnson, M. A.
    Jones, S. A.
    Jonsell, Svante
    Stockholm University, Faculty of Science, Department of Physics.
    Kurchaninov, L.
    Madsen, N.
    Mathers, M.
    Maxwell, D.
    McKenna, J. T. K.
    Menary, S.
    Michan, J. M.
    Momose, T.
    Munich, J. J.
    Nolan, P.
    Olchanski, K.
    Olin, A.
    Pusa, P.
    Rasmussen, C. O.
    Robicheaux, F.
    Sacramento, R. L.
    Sameed, M.
    Sarid, E.
    Silveira, D. M.
    Stracka, S.
    Stutter, G.
    So, C.
    Tharp, T. D.
    Thompson, J. E.
    Thompson, R. I.
    Van der Werf, D. P.
    Wurtele, J. S.
    Observation of the hyperfine spectrum of antihydrogen2017In: Nature, ISSN 0028-0836, E-ISSN 1476-4687, Vol. 548, no 7665, p. 66-+Article in journal (Refereed)
    Abstract [en]

    The observation of hyperfine structure in atomic hydrogen by Rabi and co-workers(1-3) and the measurement(4) of the zero-field ground-state splitting at the level of seven parts in 10(13) are important achievements of mid-twentieth-century physics. The work that led to these achievements also provided the first evidence for the anomalous magnetic moment of the electron(5-8), inspired Schwinger's relativistic theory of quantum electrodynamics(9,10) and gave rise to the hydrogen maser(11), which is a critical component of modern navigation, geo-positioning and very-long-baseline interferometry systems. Research at the Antiproton Decelerator at CERN by the ALPHA collaboration extends these enquiries into the antimatter sector. Recently, tools have been developed that enable studies of the hyperfine structure of antihydrogen(12)-the antimatter counterpart of hydrogen. The goal of such studies is to search for any differences that might exist between this archetypal pair of atoms, and thereby to test the fundamental principles on which quantum field theory is constructed. Magnetic trapping of antihydrogen atoms(13,14) provides a means of studying them by combining electromagnetic interaction with detection techniques that are unique to antimatter(12,15). Here we report the results of a microwave spectroscopy experiment in which we probe the response of antihydrogen over a controlled range of frequencies. The data reveal clear and distinct signatures of two allowed transitions, from which we obtain a direct, magnetic-field-independent measurement of the hyperfine splitting. From a set of trials involving 194 detected atoms, we determine a splitting of 1,420.4 +/- 0.5 megahertz, consistent with expectations for atomic hydrogen at the level of four parts in 10(4). This observation of the detailed behaviour of a quantum transition in an atom of antihydrogen exemplifies tests of fundamental symmetries such as charge-parity-time in antimatter, and the techniques developed here will enable more-precise such tests.

  • 2098. Ahmadi, M.
    et al.
    Alves, B. X. R.
    Baker, C. J.
    Bertsche, W.
    Butler, E.
    Capra, A.
    Carruth, C.
    Cesar, C. L.
    Charlton, M.
    Cohen, S.
    Collister, R.
    Eriksson, S.
    Evans, A.
    Evetts, N.
    Fajans, J.
    Friesen, T.
    Fujiwara, M. C.
    Gill, D. R.
    Gutierrez, A.
    Hangst, J. S.
    Hardy, W. N.
    Hayden, M. E.
    Isaac, C. A.
    Ishida, A.
    Johnson, M. A.
    Jones, S. A.
    Jonsell, Svante
    Stockholm University, Faculty of Science, Department of Physics.
    Kurchaninov, L.
    Madsen, N.
    Mathers, M.
    Maxwell, D.
    McKenna, J. T. K.
    Menary, S.
    Michan, J. M.
    Momose, T.
    Munich, J. J.
    Nolan, P.
    Olchanski, K.
    Olin, A.
    Pusa, P.
    Rasmussen, C. Ø.
    Robicheaux, F.
    Sacramento, R. L.
    Sameed, M.
    Sarid, E.
    Silveira, D. M.
    Stracka, S.
    Stutter, G.
    So, C.
    Tharp, T. D.
    Thompson, J. E.
    Thompson, R. I.
    van der Werf, D. P.
    Wurtele, J. S.
    Antihydrogen accumulation for fundamental symmetry tests2017In: Nature Communications, ISSN 2041-1723, E-ISSN 2041-1723, Vol. 8, article id 681Article in journal (Refereed)
    Abstract [en]

    Antihydrogen, a positron bound to an antiproton, is the simplest anti-atom. Its structure and properties are expected to mirror those of the hydrogen atom. Prospects for precision comparisons of the two, as tests of fundamental symmetries, are driving a vibrant programme of research. In this regard, a limiting factor in most experiments is the availability of large numbers of cold ground state antihydrogen atoms. Here, we describe how an improved synthesis process results in a maximum rate of 10.5 +/- 0.6 atoms trapped and detected per cycle, corresponding to more than an order of magnitude improvement over previous work. Additionally, we demonstrate how detailed control of electron, positron and antiproton plasmas enables repeated formation and trapping of antihydrogen atoms, with the simultaneous retention of atoms produced in previous cycles. We report a record of 54 detected annihilation events from a single release of the trapped anti-atoms accumulated from five consecutive cycles.

  • 2099. Ahmadi, M.
    et al.
    Alves, B. X. R.
    Baker, C. J.
    Bertsche, W.
    Capra, A.
    Carruth, C.
    Cesar, C. L.
    Charlton, M.
    Cohen, S.
    Collister, R.
    Eriksson, S.
    Evans, A.
    Evetts, N.
    Fajans, J.
    Friesen, T.
    Fujiwara, M. C.
    Gill, D. R.
    Hangst, J. S.
    Hardy, W. N.
    Hayden, M. E.
    Hunter, E. D.
    Isaac, C. A.
    Johnson, M. A.
    Jones, J. M.
    Jones, S. A.
    Jonsell, Svante
    Stockholm University, Faculty of Science, Department of Physics.
    Khramov, A.
    Knapp, P.
    Kurchaninov, L.
    Madsen, N.
    Maxwell, D.
    McKenna, J. T. K.
    Menary, S.
    Michan, J. M.
    Momose, T.
    Munich, J. J.
    Olchanski, K.
    Olin, A.
    Pusa, P.
    Rasmussen, C. O.
    Robicheaux, F.
    Sacramento, R. L.
    Sameed, M.
    Sarid, E.
    Silveira, D. M.
    Starko, D. M.
    Stutter, G.
    So, C.
    Tharp, T. D.
    Thompson, R. I.
    van der Werf, D. P.
    Wurtele, J. S.
    Observation of the 1S-2P Lyman-alpha transition in antihydrogen2018In: Nature, ISSN 0028-0836, E-ISSN 1476-4687, Vol. 561, no 7722, p. 211-217Article in journal (Refereed)
    Abstract [en]

    In 1906, Theodore Lyman discovered his eponymous series of transitions in the extreme-ultraviolet region of the atomic hydrogen spectrum(1,2). The patterns in the hydrogen spectrum helped to establish the emerging theory of quantum mechanics, which we now know governs the world at the atomic scale. Since then, studies involving the Lyman-alpha line-the 1S-2P transition at a wavelength of 121.6 nanometres-have played an important part in physics and astronomy, as one of the most fundamental atomic transitions in the Universe. For example, this transition has long been used by astronomers studying the intergalactic medium and testing cosmological models via the so-called 'Lyman-alpha forest('3) of absorption lines at different redshifts. Here we report the observation of the Lyman-alpha transition in the antihydrogen atom, the antimatter counterpart of hydrogen. Using narrow-line-width, nanosecond-pulsed laser radiation, the 1S-2P transition was excited in magnetically trapped antihydrogen. The transition frequency at a field of 1.033 tesla was determined to be 2,466,051.7 +/- 0.12 gigahertz (1 sigma uncertainty) and agrees with the prediction for hydrogen to a precision of 5 x 10(-8). Comparisons of the properties of antihydrogen with those of its well-studied matter equivalent allow precision tests of fundamental symmetries between matter ;and antimatter. Alongside the ground-state hyperfine(4,5) and 1S-2S transitions(6,7) recently observed in antihydrogen, the Lyman-alpha transition will permit laser cooling of antihydrogen(8,9), thus providing a cold and dense sample of anti-atoms for precision spectroscopy and gravity measurements(10). In addition to the observation of this fundamental transition, this work represents both a decisive technological step towards laser cooling of antihydrogen, and the extension of antimatter spectroscopy to quantum states possessing orbital angular momentum.

  • 2100. Ahmadi, M.
    et al.
    Alves, B. X. R.
    Baker, C. J.
    Bertsche, W.
    Capra, A.
    Carruth, C.
    Cesar, C. L.
    Charlton, M.
    Cohen, S.
    Collister, R.
    Eriksson, S.
    Evans, A.
    Evetts, N.
    Fajans, J.
    Friesen, T.
    Fujiwara, M. C.
    Gill, D. R.
    Hangst, J. S.
    Hardy, W. N.
    Hayden, M. E.
    Isaac, C. A.
    Johnson, M. A.
    Jones, J. M.
    Jones, S. A.
    Jonsell, Svante
    Stockholm University, Faculty of Science, Department of Physics.
    Khramov, A.
    Knapp, P.
    Kurchaninov, L.
    Madsen, N.
    Maxwell, D.
    McKenna, J. T. K.
    Menary, S.
    Momose, T.
    Munich, J. J.
    Olchanski, K.
    Olin, A.
    Pusa, P.
    Rasmussen, C. O.
    Robicheaux, F.
    Sacramento, R. L.
    Sameed, M.
    Sarid, E.
    Silveira, D. M.
    Stutter, G.
    So, C.
    Tharp, T. D.
    Thompson, R. I.
    van der Werf, D. P.
    Wurtele, J. S.
    Characterization of the 1S-2S transition in antihydrogen2018In: Nature, ISSN 0028-0836, E-ISSN 1476-4687, Vol. 557, no 7703, p. 71-+Article in journal (Refereed)
    Abstract [en]

    In 1928, Dirac published an equation(1) that combined quantum mechanics and special relativity. Negative-energy solutions to this equation, rather than being unphysical as initially thought, represented a class of hitherto unobserved and unimagined particles-antimatter. The existence of particles of antimatter was confirmed with the discovery of the positron(2) (or anti-electron) by Anderson in 1932, but it is still unknown why matter, rather than antimatter, survived after the Big Bang. As a result, experimental studies of antimatter(3-7), including tests of fundamental symmetries such as charge-parity and charge-parity-time, and searches for evidence of primordial antimatter, such as antihelium nuclei, have high priority in contemporary physics research. The fundamental role of the hydrogen atom in the evolution of the Universe and in the historical development of our understanding of quantum physics makes its antimatter counterpart-the antihydrogen atom-of particular interest. Current standard-model physics requires that hydrogen and antihydrogen have the same energy levels and spectral lines. The laser-driven 1S-2S transition was recently observed(8) in antihydrogen. Here we characterize one of the hyperfine components of this transition using magnetically trapped atoms of antihydrogen and compare it to model calculations for hydrogen in our apparatus. We find that the shape of the spectral line agrees very well with that expected for hydrogen and that the resonance frequency agrees with that in hydrogen to about 5 kilohertz out of 2.5 x 10(15) hertz. This is consistent with charge-parity-time invariance at a relative precision of 2 x 10(-12)-two orders of magnitude more precise than the previous determination(8)-corresponding to an absolute energy sensitivity of 2 x 10(-20) GeV.

39404142434445 2051 - 2100 of 104413
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