Change search
Refine search result
17181920212223 951 - 1000 of 104615
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 951.
    Acar, Patricja
    et al.
    Stockholm University, Faculty of Social Sciences, Department of Child and Youth Studies.
    Lundberg, Jonas
    Stockholm University, Faculty of Social Sciences, Department of Child and Youth Studies.
    Om barn i skolan med ADHD: Pedagogers erfarenheter av att arbeta med barn med ADHD2013Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Studiens syfte är att se vad olika sorters pedagoger inom skolan skulle kunna berätta och beskriva om vad de har för erfarenhet och om arbetet med elever med diagnosen ADHD, vilka utmaningar som möts och vilka arbetssätt som kan användas. Kvalitativa intervjuer var den metod som användes, och intervjuerna spelades in med mobiltelefon för att inte missa vad pedagogerna från de fyra olika skolorna som intervjuades berättade och beskrev. Som teoretiskt perspektiv valdes behaviorismen som användes som analysverktyg för analysen. Resultatet visar att det inte bara finns ett arbetssätt pedagogerna använder utan av flera olika metoder. Den visar även deras erfarenheter och utmaningar av- och i skolan. Pedagogerna menade också att det finns många utmaningar i mötet med barn med ADHD, då ett barn som har ADHD sällan bara har en renodlad ADHD utan även någon tilläggsdiagnos eller språkstörning. Det man kan säga är att det krävs mer kunskap om ADHD för att vidare hitta lämpliga arbetssätt, att använda sig av rätt verktyg för att vidare kunna nå ut till alla elever och inte enbart de så kallade "normal klassade" barnen.

  • 952.
    Acaralp, Linnéa
    Stockholm University, Faculty of Social Sciences, Department of Political Science.
    U.S. Drone Attacks and the Proportionality Principle: Growing ignorance or Consciousness?2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This thesis focuses on the usage of military drones, a type of semi-autonomous weapon, which has shifted the premises of conventional warfare, particularly relating to the ethics and legality of warfare. This paper examines the conditions that affect the civilian casualties in United States (U.S.) drone attacks. Drawing on Graham Allison’s work on the factors that influence U.S. foreign policy decision making, I theorize that civilian collateral casualties are more likely under certain conditions. These conditions changes depending on the type of administration in office, level of organization pressure, and the value and level of risk a target directs towards the U.S. In light of the discussion and the effect of drones on civilian casualties a debate upon the proportionality principle will be assessed. In the assessment a cost and benefit analysis is made between the military goal and civilian casualties (Gardam,1993). The proportionality principle refers to the balancing act of the excessive use of force on civilians in relation to the military goal.

    This paper is using a quantitative method. This study investigate data on US drone attacks, sourced from Bureau of Investigative Journalism, covering 733 attacks in four countries (Afghanistan, Yemen, Somalia and Pakistan) during the time period from 2002 to 2016. Based on Allison’s model three hypotheses are formulated and evaluated against the data using descriptive statistic and t-tests. The empirical result suggests that there was a statistical significance in all three hypotheses, indicating that it was possible to detect that under certain circumstances drone attacks are more likely to lead to more civilian casualties. However, when one observed the total casualties in proportion to the civilian casualties the result was not as grand as anticipated. However, the findings of this paper illustrates a pattern that during certain premises and cost and benefit analyses, the usage of drones are causing a greater risk towards civilians. Thus, these discussions further develop an already existing debate on today’s focus on military autonomous weapons and the results of using such weapons. Hence, this type of study can be applied to other military autonomous weapons as well. In light of the discussion of the proportionality principle, this paper suggest that the development of autonomous military weapons should not be taken lightly and an improvement of international regulations should perhaps be made. 

  • 953.
    Acemoglu, Daron
    et al.
    MIT.
    Aghion, Philippe
    Stockholm University, Faculty of Social Sciences, Institute for International Economic Studies.
    Bursztyn, Leonardo
    Harvard.
    Hemous, David
    Harvard.
    The Environment and Directed Technical Change2010Report (Other academic)
    Abstract [en]

    This paper introduces endogenous and directed technical change in a growth model with environmental constraints. A unique final good is produced by combining inputs from two sectors. One of these sectors uses “dirty” machines and thus creates environmental degradation. Research can be directed to improving the technology of machines in either sector. We characterize dynamic tax policies that achieve sustainable growth or maximize intertemporal welfare. We show that: (i) in the case where the inputs are sufficiently substitutable, sustainable long-run growth can be achieved with temporary taxation of dirty innovation and production; (ii) optimal policy involves both “carbon taxes” and research subsidies, so that excessive use of carbon taxes is avoided; (iii) delay in intervention is costly: the sooner and the stronger is the policy response, the shorter is the growth transition phase; (iv) the use of an exhaustible resource in dirty input production helps the switch to clean innovation under laissez-faire when the two inputs are substitutes. Under reasonable parameter values and with sufficient substitutability between inputs, it is optimal to redirect technical change towards clean technologies immediately and optimal environmental regulation need not reduce long-run growth.

  • 954. Acemoglu, Daron
    et al.
    Aghion, Philippe
    Stockholm University, Faculty of Social Sciences, Institute for International Economic Studies.
    Bursztyn, Leonardo
    Hemous, David
    The Environment and Directed Technical Change2012In: The American Economic Review, ISSN 0002-8282, E-ISSN 1944-7981, Vol. 102, no 1, p. 131-166Article in journal (Refereed)
    Abstract [en]

    This paper introduces endogenous and directed technical change in a growth model with environmental constraints. The final good is produced from dirty and clean inputs. We show that: (i) when inputs are sufficiently substitutable, sustainable growth can be achieved with temporary taxes/subsidies that redirect innovation toward clean inputs; (ii) optimal policy involves both carbon taxes and research subsidies, avoiding excessive use of carbon taxes; (iii) delay in intervention is costly, as it later necessitates a longer transition phase with slow growth; and (iv) use of an exhaustible resource in dirty input production helps the switch to clean innovation under laissez-faire.

  • 955.
    Acemoglu, Daron
    et al.
    MIT Department of Economics.
    Aghion, Philippe
    Stockholm University, Faculty of Social Sciences, Institute for International Economic Studies.
    Griffith, Rachel
    UCL.
    Zilibotti, Fabrizio
    Stockholm University, Faculty of Social Sciences, Institute for International Economic Studies.
    Vertical Integration and Technology: Theory and Evidence2010In: Journal of the European Economic Association, ISSN 1542-4766, E-ISSN 1542-4774, Vol. 8, no 5, p. 989-1033Article in journal (Refereed)
  • 956. Acemoglu, Daron
    et al.
    Aghion, Philippe
    Lelarge, Claire
    Van Reenen, John
    Zilibotti, Fabrizio
    Stockholm University, Faculty of Social Sciences, Institute for International Economic Studies.
    Technology, Information, and the Decentralization of the Firm2007In: Quarterly Journal of Economics, Vol. 122, no 4, p. 1759-1799Article in journal (Refereed)
    Abstract [en]

    This paper analyzes the relationship between the diffusion of new technologies and the decentralization of firms. Centralized control relies on the information of the principal, which we equate with publicly available information. Decentralized control, on the other hand, delegates authority to a manager with superior information. However, the manager can use his informational advantage to make choices that are not in the best interest of the principal. As the available public information about the specific technology increases, the tradeoff shifts in favor of centralization. We show that firms closer to the technological frontier, firms in more heterogeneous environments, and younger firms are more likely to choose decentralization. Using three data sets on French and British firms in the 1990s, we report robust correlations consistent with these predictions.

  • 957.
    Acemoglu, Daron
    et al.
    Massachusetts Institute of Technology.
    Zilibotti, Fabrizio
    Universitat Pompeu Fabra.
    Agency Costs in the Process of Development1996Report (Other academic)
    Abstract [en]

    We analyze an economy where production is subject to moral hazard. The degree of the incentive (agency) costs introduced by the presence of moral hazard naturally depends on the information structure in the economy; it is cheaper to induce correct incentives in a society which posesses better ex post information. The degree of ex post information depends on the number of projects and entrepreneurs in the economy; the more projects, the better the information. This implies that at the early stages of development, the range of projects and the amount of information are limited and agency costs are high. Since the information created by a project is an externality on others, the decentralized economy is constrained inefficient; in particular, it does not 'experiment' enough. The analysis of the role of information also opens the way to an investigation of the development of financial institutions. We contrast the information aggregation role of stock markets and information production role of banks. Because the amount of available information increases with development, our model predicts the pattern of financial development observed in practice; banks first and stock markets later.

  • 958.
    Acemoglu, Daron
    et al.
    Masachusetts Institute of Technology.
    Zilibotti, Fabrizio
    Stockholm University, Faculty of Social Sciences, Institute for International Economic Studies.
    Information Accumulation in Development1998Report (Other academic)
    Abstract [en]

    We propose a model in which economic relations and intritutions in advanced and less developed countries differ as these societies have access to different amounts of information. The lack of information in less developed economies makes it hard to evaluate the performance of manager, and leads to high "agency costs". Differences in the amount of information have a variety of sources. As well as factors related to the informational infrastructure, we emphasize that societies accumulate information partly because the scarcity of capital restricts the repetition of various activities. Two implications of our model are: (i) as an economy develops and generates more information, it achieves better risk-sharing at a given level of effort, but because agents are exerting more effort and the types of activities are changing, the overall level of risk-sharing may decline; (ii) with development, the share of financial intermediation carried out through market institutions should increase.

  • 959.
    Acemoglu, Daron
    et al.
    Massachusetts Institute of Technology.
    Zilibotti, Fabrizio
    Stockholm University, Faculty of Social Sciences, Institute for International Economic Studies.
    Productivity Differences1998Report (Other academic)
    Abstract [en]

    Many technologies used by the LDCs are developed in the OECD economies, and as such, are designed to make optimal use of the skills of these richer countries' workforces. Due to differences in the supply of skills, some of the tasks performed by skilled workers in the OECD economies will be carried out by unskilled workers in the LDCs. Since the technologies in these tasks are designed to be used by skilled workers, productivity in the LDCs will be low. Even when all countries have equal access to new technologies, this mismatch between skills and technology can lead to sizable differences in total factor productivity and output per worker. Our theory also suggests that productivity differences should be highest in medium-tech sectors, and that the trade regime and the degree of intellectual property right enforcement in the LDCs have an important effect on the direction of technical change and on productivity differences.

  • 960.
    Acerbi, Alberto
    et al.
    Stockholm University, Faculty of Humanities, Centre for the Study of Cultural Evolution.
    Bentley, R. Alexander
    Biases in cultural transmission shape the turnover of popular traits2014In: Evolution and human behavior, ISSN 1090-5138, E-ISSN 1879-0607, Vol. 35, p. 228-236Article in journal (Refereed)
    Abstract [en]

    The neutral model of cultural evolution, which assumes that copying is unbiased, provides precise predictions regarding frequency distributions of traits and the turnover within a popularity-ranked list. Here we study turnover in ranked lists and identify where the turnover departs from neutral model predictions to detect transmission biases in three different domains: color terms usage in English language 20th century books, popularity of early (1880–1930) and recent (1960–2010) USA baby names, and musical preferences of users of the Web site Last.fm. To help characterize the type of transmission bias, we modify the neutral model to include a content-based bias and two context-based biases (conformity and anti-conformity). How these modified models match real data helps us to infer, from population scale observations, when cultural transmission is biased, and, to some extent, what kind of biases are operating at individual level.

  • 961.
    Acerbi, Alberto
    et al.
    Department of Psychology, University of Bologna.
    Enquist, Magnus
    Stockholm University, Faculty of Humanities, Centre for the Study of Cultural Evolution. Stockholm University, Faculty of Science, Department of Zoology, Department of Ethology.
    Ghirlanda, Stefano
    Stockholm University, Faculty of Humanities, Centre for the Study of Cultural Evolution.
    Cultural evolution and individual development of openness and conservatism2009In: Proceedings of the National Academy of Sciences of the United States of America, ISSN 0027-8424, E-ISSN 1091-6490, Vol. 106, no 45, p. 18931-18935Article in journal (Refereed)
    Abstract [en]

    We present a model of cultural evolution in which an individual's propensity to engage in social learning is affected by social learning itself. We assume that individuals observe cultural traits displayed by others and decide whether to copy them based on their overall preference for the displayed traits. Preferences, too, can be transmitted between individuals. Our results show that such cultural dynamics tends to produce conservative individuals, i.e., individuals who are reluctant to copy new traits. Openness to new information, however, can be maintained when individuals need significant time to acquire the cultural traits that make them effective cultural models. We show that a gradual enculturation of young individuals by many models and a larger cultural repertoire to be acquired are favorable circumstances for the long-term maintenance of openness in individuals and groups. Our results agree with data about lifetime personality change, showing that openness to new information decreases with age. Our results show that cultural remodeling of cultural transmission is a powerful force in cultural evolution, i.e., that cultural evolution can change its own dynamics

  • 962. Acerbi, Alberto
    et al.
    Ghirlanda, Stefano
    Enquist, Magnus
    Stockholm University, Faculty of Humanities, Centre for Cultural Evolution.
    Old and Young Individuals' Role in Cultural Change2012In: JASSS: Journal of Artificial Societies and Social Simulation, ISSN 1460-7425, E-ISSN 1460-7425, Vol. 15, no 4, article id 1Article in journal (Refereed)
    Abstract [en]

    We explore the impact of age on cultural change through simulations of cultural evolution. Our simulations show that common observations about the relationship between old and young naturally emerge from repeated cultural learning. In particular, young individuals are more open to learn than older individuals, they are less effective as cultural models, and they possess less cultural traits. We also show that, being more open to learning, young individuals are an important source of cultural change. Cultural change, however, is faster in populations with both young and old. A relatively large share of older individuals, in fact, allows a population to retain more culture, and a large culture can change in more directions than a small culture. For the same reason, considering age-biased cultural transmission in an overlapping generations model, cultural evolution is slower when individuals interact preferentially with models of similar age than when they mainly interact with older models.

  • 963.
    Acerbi, Alberto
    et al.
    Stockholm University, Faculty of Humanities, Centre for the Study of Cultural Evolution.
    Ghirlanda, Stefano
    Stockholm University, Faculty of Humanities, Centre for the Study of Cultural Evolution. Brooklyn College, USA.
    Enquist, Magnus
    Stockholm University, Faculty of Humanities, Centre for the Study of Cultural Evolution. Stockholm University, Faculty of Science, Department of Zoology.
    Regulatory traits: Cultural influences on cultural evolution2014In: Evolution, Complexity and Artificial Life / [ed] Stefano Cagnoni, Marco Mirolli, Marco Villani, Springer Berlin/Heidelberg, 2014, p. 135-147Chapter in book (Refereed)
    Abstract [en]

    We use the term regulatory traits to indicate traits that both regulate cultural transmission (e.g., from whom to learn) and are themselves culturally transmitted. In the first part of this contribution we study the dynamics of some of these traits through simple mathematical models. In particular, we consider the cultural evolution of traits that determine the propensity to copy others, the ability to influence others, the number of individuals from whom one may copy, and the number of individuals one tries to influence. We then show how to extend these simple models to address more complex human cultural phenomena, such as ingroup biases, the emergence of open or conservative societies, and of cyclical, fashion-like, increases and decreases of popularity of cultural traits. We finally discuss how the ubiquity of regulatory traits in cultural evolution impacts on the analogy between genetic and cultural evolution and therefore on the possibility of using models inspired by evolutionary biology to study human cultural dynamics.

  • 964.
    Acerbi, Alberto
    et al.
    Stockholm University, Faculty of Humanities, Centre for Cultural Evolution.
    Ghirlanda, Stefano
    Stockholm University, Faculty of Humanities, Centre for Cultural Evolution. Brooklyn College, US.
    Enquist, Magnus
    Stockholm University, Faculty of Humanities, Centre for Cultural Evolution. Stockholm University, Faculty of Science, Department of Zoology, Ethology.
    Regulatory Traits in Cultural Evolution2012In: Proceedings of WiVACE 2012, 2012, p. 1-9Conference paper (Refereed)
    Abstract [en]

    We call "regulatory traits" those cultural traits that are transmitted through cultural interactions and, at the same time, change individual behaviors directly influencing the outcome of future cultural interactions. The cultural dynamics of some of those traits are studied through simple simulations. In particular, we consider the cultural evolution of traits determining the propensity to copy, the number of potential demonstrators from whom one individual may copy, and conformist versus anti conformist attitudes. Our results show that regulatory traits generate peculiar dynamics that may explain complex human cultural phenomena. We discuss how the existence and importance of regulatory traits in cultural evolution impact on the analogy between genetic and cultural evolution and therefore on the possibility of using evolutionary biology inspired models to study human cultural dynamics.

  • 965.
    Acerbi, Alberto
    et al.
    Stockholm University, Faculty of Humanities, Centre for the Study of Cultural Evolution.
    Ghirlanda, Stefano
    Stockholm University, Faculty of Humanities, Centre for the Study of Cultural Evolution.
    Enquist, Magnus
    Stockholm University, Faculty of Humanities, Centre for the Study of Cultural Evolution. Stockholm University, Faculty of Science, Department of Zoology.
    The logic of fashion cycles2012In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 7, no 3, p. e32541-Article in journal (Refereed)
    Abstract [en]

    Many cultural traits exhibit volatile dynamics, commonly dubbed fashions or fads. Here we show that realistic fashion-like dynamics emerge spontaneously if individuals can copy others' preferences for cultural traits as well as traits themselves. We demonstrate this dynamics in simple mathematical models of the diffusion, and subsequent abandonment, of a single cultural trait which individuals may or may not prefer. We then simulate the coevolution between many cultural traits and the associated preferences, reproducing power-law frequency distributions of cultural traits (most traits are adopted by few individuals for a short time, and very few by many for a long time), as well as correlations between the rate of increase and the rate of decrease of traits (traits that increase rapidly in popularity are also abandoned quickly and vice versa). We also establish that alternative theories, that fashions result from individuals signaling their social status, or from individuals randomly copying each other, do not satisfactorily reproduce these empirical observations.

  • 966.
    Acerbi, Alberto
    et al.
    Stockholm University, Faculty of Humanities, Centre for Cultural Evolution.
    Jacquet, Pierre O.
    Tennie, Claudio
    Behavioral constraints and the evolution of faithful social learning2012In: Current Zoology, ISSN 1674-5507, Vol. 58, no 2, p. 307-318Article in journal (Refereed)
    Abstract [en]

    Behavioral “traditions”, i.e. behavioral patterns that are acquired with the aid of social learning and that are relativelystable in a group, have been observed in several species. Recently, however, it has been questioned whether non-human sociallearning is faithful enough to stabilize those patterns. The observed stability could be interpreted as a result of various constraintsthat limit the number of possible alternative behaviors, rather than of the fidelity of transmission mechanisms. Those constraints canbe roughly described as “internal”, such as mechanical (bodily) properties or cognitive limitations and predispositions, and “external”, such as ecological availability or pressures. Here we present an evolutionary individual-based model that explores the relationships between the evolution of faithful social learning and behavioral constraints, represented both by the size of the behavioral repertoire and by the “shape” of the search space of a given task. We show that the evolution of high-fidelity transmission mechanisms, when associated with costs (e.g. cognitive, biomechanical, energetic, etc.), is only likely if the potential behavioral repertoire of a species is large and if the search space does not provide information that can be exploited by individual learning. Moreover we show how stable behavioral patterns (“traditions”) can be achieved at the population level as an outcome of both high-fidelity and low-fidelity transmission mechanisms, given that the latter are coupled with a small behavioral repertoire or with a search space that provide substantial feedback. Finally, by introducing the possibility of environmental change, we show that intermediaterates of change favor the evolution of faithful social learning.

  • 967.
    Acerbi, Alberto
    et al.
    Stockholm University, Faculty of Humanities, Centre for the Study of Cultural Evolution. University of Bristol, United Kingdom.
    Lampos, Vasileios
    Garnett, Philip
    Bentley, R. Alexander
    The Expression of Emotions in 20th Century Books2013In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 8, no 3, article id e59030Article in journal (Refereed)
    Abstract [en]

    We report here trends in the usage of mood words, that is, words carrying emotional content, in 20th century English language books, using the data set provided by Google that includes word frequencies in roughly 4% of all books published up to the year 2008. We find evidence for distinct historical periods of positive and negative moods, underlain by a general decrease in the use of emotion-related words through time. Finally, we show that, in books, American English has become decidedly more emotional than British English in the last half-century, as a part of a more general increase of the stylistic divergence between the two variants of English language.

  • 968.
    Acerbi, Alberto
    et al.
    Stockholm University, Faculty of Humanities, Centre for the Study of Cultural Evolution.
    Nunn, Charles
    Harvard University, Department of Human Evolutionary Biology.
    Predation and the phasing of sleep: an evolutionary individual-based model2011In: Animal Behaviour, ISSN 0003-3472, E-ISSN 1095-8282, Vol. 81, no 4, p. 801-811Article in journal (Refereed)
    Abstract [en]

    All mammals thus far studied sleep, yet important questions remain concerning the ecological factors that influence sleep patterns. Here, we developed an evolutionary individual-based model to investigate the effect of predation pressure on prey sleep. We investigated three ecological conditions, including one that assumed a dynamic interaction between predator and prey behaviour. In condition 1, we found that monophasic predators (i.e. with one sleep bout per 24 h) select for monophasic prey that sleep perfectly out of phase with predators. In condition 2, predators were monophasic but the safety of prey varied as a function of their activity (sleeping versus awake). In this condition, the prey adjusted their sleeping behaviour to lower the risk of predation. Finally, in condition 3, we modelled a more dynamic interaction between predator and prey, with predator activity dependent on prey activity in the previous hour. In this scenario, the prey adjusted their behaviour relative to one another, resulting in either greater or lesser synchrony in prey as a function of predator searching behaviour. Collectively, our model demonstrates that predator behaviour can have a strong influence on prey sleep patterns, including whether prey are monophasic or polyphasic (i.e. with many sleep bouts per 24 h). The model further suggests that the timing of sleep relative to predator behaviour may depend strongly on how other potential prey partition the activity period.

  • 969.
    Acerbi, Alberto
    et al.
    Stockholm University, Faculty of Humanities, Centre for the Study of Cultural Evolution.
    Tennie, Claudio
    Nunn, Charles
    Modeling imitation and emulation in constrained search spaces2011In: Animal Learning and Behavior, ISSN 0090-4996, E-ISSN 1532-5830, Vol. 39, no 2, p. 104-114Article in journal (Refereed)
    Abstract [en]

    Social transmission of behavior can be realized through distinct mechanisms. Research on primate social learning typically distinguishes two forms of information that a learner can extract from a demonstrator: copying actions (defined as imitation) or copying only the consequential results (defined as emulation). We propose a decomposition of these learning mechanisms (plus pure individual learning) that incorporates the core idea that social learning can be represented as a search for an optimal behavior that is constrained by different kinds of information. We illustrate our approach with an individual-based model in which individuals solve tasks in abstract “spaces” that represent behavioral actions, results, and benefits of those results. Depending on the learning mechanisms at their disposal, individuals have differential access to the information conveyed in these spaces. We show how different classes of tasks may provide distinct advantages to individuals with different learning mechanisms and discuss how our approach contributes to current empirical and theoretical research on social learning and culture.

  • 970. Acero, F.
    et al.
    Ackermann, M.
    Ajello, M.
    Albert, A.
    Atwood, W. B.
    Axelsson, Magnus
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Baldini, L.
    Ballet, J.
    Barbiellini, G.
    Bastieri, D.
    Belfiore, A.
    Bellazzini, R.
    Bissaldi, E.
    Blandford, R. D.
    Bloom, E. D.
    Bogart, J. R.
    Bonino, R.
    Bottacini, E.
    Bregeon, J.
    Britto, R. J.
    Bruel, P.
    Buehler, R.
    Burnett, T. H.
    Buson, S.
    Caliandro, G. A.
    Cameron, R. A.
    Caputo, R.
    Caragiulo, M.
    Caraveo, P. A.
    Casandjian, J. M.
    Cavazzuti, E.
    Charles, E.
    Chaves, R. C. G.
    Chekhtman, A.
    Cheung, C. C.
    Chiang, J.
    Chiaro, G.
    Ciprini, S.
    Claus, R.
    Cohen-Tanugi, J.
    Cominsky, L. R.
    Conrad, Jan
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC). Royal Swedish Academy of Science, Sweden.
    Cutini, S.
    D'Ammando, F.
    de Angelis, A.
    DeKlotz, M.
    de Palma, F.
    Desiante, R.
    Digel, S. W.
    Di Venere, L.
    Drell, P. S.
    Dubois, R.
    Dumora, D.
    Favuzzi, C.
    Fegan, S. J.
    Ferrara, E. C.
    Finke, J.
    Franckowiak, A.
    Fukazawa, Y.
    Funk, S.
    Fusco, P.
    Gargano, F.
    Gasparrini, D.
    Giebels, B.
    Giglietto, N.
    Giommi, P.
    Giordano, F.
    Giroletti, M.
    Glanzman, T.
    Godfrey, G.
    Grenier, I. A.
    Grondin, M. -H.
    Grove, J. E.
    Guillemot, L.
    Guiriec, S.
    Hadasch, D.
    Harding, A. K.
    Hays, E.
    Hewitt, J. W.
    Hill, A. B.
    Horan, D.
    Iafrate, G.
    Jogler, T.
    Johannesson, G.
    Johnson, R. P.
    Johnson, A. S.
    Johnson, T. J.
    Johnson, W. N.
    Kamae, T.
    Kataoka, J.
    Katsuta, J.
    Kuss, M.
    La Mura, G.
    Landriu, D.
    Larsson, Stefan
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Latronico, L.
    Lemoine-Goumard, M.
    Li, J.
    Li, L.
    Longo, F.
    Loparco, F.
    Lott, B.
    Lovellette, M. N.
    Lubrano, P.
    Madejski, G. M.
    Massaro, F.
    Mayer, M.
    Mazziotta, M. N.
    McEnery, J. E.
    Michelson, P. F.
    Mirabal, N.
    Mizuno, T.
    Moiseev, A. A.
    Mongelli, M.
    Monzani, M. E.
    Morselli, A.
    Moskalenko, I. V.
    Murgia, S.
    Nuss, E.
    Ohno, M.
    Ohsugi, T.
    Omodei, N.
    Orienti, M.
    Orlando, E.
    Ormes, J. F.
    Paneque, D.
    Panetta, J. H.
    Perkins, J. S.
    Pesce-Rollins, M.
    Piron, F.
    Pivato, G.
    Porter, T. A.
    Racusin, J. L.
    Rando, R.
    Razzano, M.
    Razzaque, S.
    Reimer, A.
    Reimer, O.
    Reposeur, T.
    Rochester, L. S.
    Romani, R. W.
    Salvetti, D.
    Sanchez-Coude, Miguel
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Parkinson, P. M. Saz
    Schulz, A.
    Siskind, E. J.
    Smith, D. A.
    Spada, F.
    Spandre, G.
    Spinelli, P.
    Stephens, T. E.
    Strong, A. W.
    Suson, D. J.
    Takahashi, H.
    Takahashi, T.
    Tanaka, Y.
    Thayer, J. G.
    Thayer, J. B.
    Thompson, D. J.
    Tibaldo, L.
    Tibolla, O.
    Torres, D. F.
    Torresi, E.
    Tosti, G.
    Troja, E.
    Van Klaveren, B.
    Vianello, G.
    Winer, B. L.
    Wood, K. S.
    Wood, M.
    Zimmer, Stephan
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    FERMI LARGE AREA TELESCOPE THIRD SOURCE CATALOG2015In: Astrophysical Journal Supplement Series, ISSN 0067-0049, E-ISSN 1538-4365, Vol. 218, no 2, article id 23Article in journal (Refereed)
    Abstract [en]

    We present the third Fermi Large Area Telescope (LAT) source catalog (3FGL) of sources in the 100 MeV-300 GeV range. Based on the first 4 yr of science data from the Fermi Gamma-ray Space Telescope mission, it is the deepest yet in this energy range. Relative to the Second Fermi LAT catalog, the 3FGL catalog incorporates twice as much data, as well as a number of analysis improvements, including improved calibrations at the event reconstruction level, an updated model for Galactic diffuse.-ray emission, a refined procedure for source detection, and improved methods for associating LAT sources with potential counterparts at other wavelengths. The 3FGL catalog includes 3033 sources above 4 sigma significance, with source location regions, spectral properties, and monthly light curves for each. Of these, 78 are flagged as potentially being due to imperfections in the model for Galactic diffuse emission. Twenty-five sources are modeled explicitly as spatially extended, and overall 238 sources are considered as identified based on angular extent or correlated variability (periodic or otherwise) observed at other wavelengths. For 1010 sources we have not found plausible counterparts at other wavelengths. More than 1100 of the identified or associated sources are active galaxies of the blazar class; several other classes of non-blazar active galaxies are also represented in the 3FGL. Pulsars represent the largest Galactic source class. From source counts of Galactic sources we estimate that the contribution of unresolved sources to the Galactic diffuse emission is similar to 3% at 1 GeV.

  • 971. Acero, F.
    et al.
    Ackermann, M.
    Ajello, M.
    Albert, A.
    Baldini, L.
    Ballet, J.
    Barbiellini, G.
    Bastieri, D.
    Bellazzini, R.
    Bissaldi, E.
    Bloom, E. D.
    Bonino, R.
    Bottacini, E.
    Brandt, T. J.
    Bregeon, J.
    Bruel, P.
    Buehler, R.
    Buson, S.
    Caliandro, G. A.
    Cameron, R. A.
    Caragiulo, M.
    Caraveo, P. A.
    Casandjian, J. M.
    Cavazzuti, E.
    Cecchi, C.
    Charles, E.
    Chekhtman, A.
    Chiang, J.
    Chiaro, G.
    Ciprini, S.
    Claus, R.
    Cohen-Tanugi, J.
    Conrad, Jan
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Cuoco, A.
    Cutini, S.
    D'Ammando, F.
    de Angelis, A.
    de Palma, F.
    Desiante, R.
    Digel, S. W.
    Di Venere, L.
    Drell, P. S.
    Favuzzi, C.
    Fegan, S. J.
    Ferrara, E. C.
    Focke, W. B.
    Franckowiak, A.
    Funk, S.
    Fusco, P.
    Gargano, F.
    Gasparrini, D.
    Giglietto, N.
    Giordano, F.
    Giroletti, M.
    Glanzman, T.
    Godfrey, G.
    Grenier, I. A.
    Guiriec, S.
    Hadasch, D.
    Harding, A. K.
    Hayashi, K.
    Hays, E.
    Hewitt, J. W.
    Hill, A. B.
    Horan, D.
    Hou, X.
    Jogler, T.
    Johannesson, G.
    Kamae, T.
    Kuss, M.
    Landriu, D.
    Larsson, Stefan
    Latronico, L.
    Li, J.
    Li, L.
    Longo, F.
    Loparco, F.
    Lovellette, M. N.
    Lubrano, P.
    Maldera, S.
    Malyshev, D.
    Manfreda, A.
    Martin, P.
    Mayer, M.
    Mazziotta, M. N.
    McEnery, J. E.
    Michelson, P. F.
    Mirabal, N.
    Mizuno, T.
    Monzani, M. E.
    Morselli, A.
    Nuss, E.
    Ohsugi, T.
    Omodei, N.
    Orienti, M.
    Orlando, E.
    Ormes, J. F.
    Paneque, D.
    Pesce-Rollins, M.
    Piron, F.
    Pivato, G.
    Raino, S.
    Rando, R.
    Razzano, M.
    Razzaque, S.
    Reimer, A.
    Reimer, O.
    Remy, Q.
    Renault, N.
    Sanchez-Conde, Miguel
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Schaal, M.
    Schulz, A.
    Sgro, C.
    Siskind, E. J.
    Spada, F.
    Spandre, G.
    Spinelli, P.
    Strong, A. W.
    Suson, D. J.
    Tajima, H.
    Takahashi, H.
    Thayer, J. B.
    Thompson, D. J.
    Tibaldo, L.
    Tinivella, M.
    Torres, D. F.
    Tosti, G.
    Troja, E.
    Vianello, G.
    Werner, M.
    Wood, K. S.
    Wood, M.
    Zaharijas, G.
    Zimmer, Stephan
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    DEVELOPMENT OF THE MODEL OF GALACTIC INTERSTELLAR EMISSION FOR STANDARD POINT-SOURCE ANALYSIS OF FERMI LARGE AREA TELESCOPE DATA2016In: Astrophysical Journal Supplement Series, ISSN 0067-0049, E-ISSN 1538-4365, Vol. 223, no 2, article id 26Article in journal (Refereed)
    Abstract [en]

    Most of the celestial. rays detected by the Large Area Telescope (LAT) on board the Fermi Gamma-ray Space Telescope originate from the interstellar medium when energetic cosmic rays interact with interstellar nucleons and photons. Conventional point-source and extended-source studies rely on the modeling of this diffuse emission for accurate characterization. Here, we describe the development of the Galactic Interstellar Emission Model (GIEM), which is the standard adopted by the LAT Collaboration and is publicly available. This model is based on a linear combination of maps for interstellar gas column density in Galactocentric annuli and for the inverse-Compton emission produced in the Galaxy. In the GIEM, we also include large-scale structures like Loop. I and the Fermi bubbles. The measured gas emissivity spectra confirm that the cosmic-ray proton density decreases with Galactocentric distance beyond 5 kpc from the Galactic Center. The measurements also suggest a softening of the proton spectrum with Galactocentric distance. We observe that the Fermi bubbles have boundaries with a shape similar to a catenary at latitudes below 20 degrees and we observe an enhanced emission toward their base extending in the north and south Galactic directions and located within similar to 4 degrees of the Galactic Center.

  • 972. Acero, F.
    et al.
    Ackermann, M.
    Ajello, M.
    Allafort, A.
    Baldini, L.
    Ballet, J.
    Barbiellini, G.
    Bastieri, D.
    Bechtol, K.
    Bellazzini, R.
    Blandford, R. D.
    Bloom, E. D.
    Bonamente, E.
    Bottacini, E.
    Brandt, T. J.
    Bregeon, J.
    Brigida, M.
    Bruel, P.
    Buehler, R.
    Buson, S.
    Caliandro, G. A.
    Cameron, R. A.
    Caraveo, P. A.
    Cecchi, C.
    Charles, E.
    Chaves, R. C. G.
    Chekhtman, A.
    Chiang, J.
    Chiaro, G.
    Ciprini, S.
    Claus, R.
    Cohen-Tanugi, J.
    Conrad, Jan
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Cutini, S.
    Dalton, M.
    D'Ammando, F.
    de Palma, F.
    Dermer, C. D.
    Di Venere, L.
    do Couto e Silva, E.
    Drell, P. S.
    Drlica-Wagner, A.
    Falletti, L.
    Favuzzi, C.
    Fegan, S. J.
    Ferrara, E. C.
    Focke, W. B.
    Franckowiak, A.
    Fukazawa, Y.
    Funk, S.
    Fusco, P.
    Gargano, F.
    Gasparrini, D.
    Giglietto, N.
    Giordano, F.
    Giroletti, M.
    Glanzman, T.
    Godfrey, G.
    Gregoire, T.
    Grenier, I. A.
    Grondin, M. -H
    Grove, J. E.
    Guiriec, S.
    Hadasch, D.
    Hanabata, Y.
    Harding, A. K.
    Hayashida, M.
    Hayashi, K.
    Hays, E.
    Hewitt, J.
    Hill, A. B.
    Horan, D.
    Hou, X.
    Hughes, R. E.
    Inoue, Y.
    SUBJackson, M. S.
    Jogler, T.
    Johannesson, G.
    Johnson, A. S.
    Kamae, T.
    Kawano, T.
    Kerr, M.
    Knoedlseder, J.
    Kuss, M.
    Lande, J.
    Larsson, Stefan
    Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC). Stockholm University, Faculty of Science, Department of Physics.
    Latronico, L.
    Lemoine-Goumard, M.
    Longo, F.
    Loparco, F.
    Lovellette, M. N.
    Lubrano, P.
    Marelli, M.
    Massaro, F.
    Mayer, M.
    Mazziotta, M. N.
    McEnery, J. E.
    Mehault, J.
    Michelson, P. F.
    Mitthumsiri, W.
    Mizuno, T.
    Monte, C.
    Monzani, M. E.
    Morselli, A.
    Moskalenko, I. V.
    Murgia, S.
    Nakamori, T.
    Nemmen, R.
    Nuss, E.
    Ohsugi, T.
    Okumura, A.
    Orienti, M.
    Orlando, E.
    Ormes, J. F.
    Paneque, D.
    Panetta, J. H.
    Perkins, J. S.
    Pesce-Rollins, M.
    Piron, F.
    Pivato, G.
    Porter, T. A.
    Raino, S.
    Rando, R.
    Razzano, M.
    Reimer, A.
    Reimer, O.
    Reposeur, T.
    Ritz, S.
    Roth, M.
    Rousseau, R.
    Parkinson, P. M. Saz
    Schulz, A.
    Sgro, C.
    Siskind, E. J.
    Smith, D. A.
    Spandre, G.
    Spinelli, P.
    Suson, D. J.
    Takahashi, H.
    Takeuchi, Y.
    Thayer, J. G.
    Thayer, J. B.
    Thompson, D. J.
    Tibaldo, L.
    Tibolla, O.
    Tinivella, M.
    Torres, D. F.
    Tosti, G.
    Troja, E.
    Uchiyama, Y.
    Vandenbroucke, J.
    Vasileiou, V.
    Vianello, G.
    Vitale, V.
    Werner, M.
    Winer, B. L.
    Wood, K. S.
    Yang, Zhaoyu
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    CONSTRAINTS ON THE GALACTIC POPULATION OF TeV PULSAR WIND NEBULAE USING FERMI LARGE AREA TELESCOPE OBSERVATIONS2013In: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 773, no 1, p. 77-Article in journal (Refereed)
    Abstract [en]

    Pulsar wind nebulae (PWNe) have been established as the most populous class of TeV gamma-ray emitters. Since launch, the Fermi Large Area Telescope (LAT) has identified five high-energy (100 MeV < E < 100 GeV) gamma-ray sources as PWNe and detected a large number of PWN candidates, all powered by young and energetic pulsars. The wealth of multi-wavelength data available and the new results provided by Fermi-LAT give us an opportunity to find new PWNe and to explore the radiative processes taking place in known ones. The TeV gamma-ray unidentified (UNID) sources are the best candidates for finding new PWNe. Using 45 months of Fermi-LAT data for energies above 10 GeV, an analysis was performed near the position of 58 TeV PWNe and UNIDs within 5. of the Galactic plane to establish new constraints on PWN properties and find new clues on the nature of UNIDs. Of the 58 sources, 30 were detected, and this work provides their gamma-ray fluxes for energies above 10 GeV. The spectral energy distributions and upper limits, in the multi-wavelength context, also provide new information on the source nature and can help distinguish between emission scenarios, i.e., between classification as a pulsar candidate or as a PWN candidate. Six new GeV PWN candidates are described in detail and compared with existing models. A population study of GeV PWN candidates as a function of the pulsar/PWN system characteristics is presented.

  • 973. Acero, F.
    et al.
    Ackermann, M.
    Ajello, M.
    Baldini, L.
    Ballet, J.
    Barbiellini, G.
    Bastieri, D.
    Bellazzini, R.
    Bissaldi, E.
    Blandford, R. D.
    Bloom, E. D.
    Bonino, R.
    Bottacini, E.
    Brandt, T. J.
    Bregeon, J.
    Bruel, P.
    Buehler, R.
    Buson, S.
    Caliandro, G. A.
    Cameron, R. A.
    Caputo, R.
    Caragiulo, M.
    Caraveo, P. A.
    Casandjian, J. M.
    Cavazzuti, E.
    Cecchi, C.
    Chekhtman, A.
    Chiang, J.
    Chiaro, G.
    Ciprini, S.
    Claus, R.
    Cohen, J. M.
    Cohen-Tanugi, J.
    Cominsky, L. R.
    Condon, B.
    Conrad, Jan
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC). The Royal Swedish Academy of Sciences, Sweden.
    Cutini, S.
    D'Ammando, F.
    de Angelis, A.
    de Palma, F.
    Desiante, R.
    Digel, S. W.
    Di Venere, L.
    Drell, P. S.
    Drlica-Wagner, A.
    Favuzzi, C.
    Ferrara, E. C.
    Franckowiak, A.
    Fukazawa, Y.
    Funk, S.
    Fusco, P.
    Gargano, F.
    Gasparrini, D.
    Giglietto, N.
    Giommi, P.
    Giordano, F.
    Giroletti, M.
    Glanzman, T.
    Godfrey, G.
    Gomez-Vargas, G. A.
    Grenier, I. A.
    Grondin, M. -H.
    Guillemot, L.
    Guiriec, S.
    Gustafsson, M.
    Hadasch, D.
    Harding, A. K.
    Hayashida, M.
    Hays, E.
    Hewitt, J. W.
    Hill, A. B.
    Horan, D.
    Hou, X.
    Iafrate, G.
    Jogler, T.
    Johannesson, G.
    Johnson, A. S.
    Kamae, T.
    Katagiri, H.
    Kataoka, J.
    Katsuta, J.
    Kerr, M.
    Knodlseder, J.
    Kocevski, D.
    Kuss, M.
    Laffon, H.
    Lande, J.
    Larsson, Stefan
    Latronico, L.
    Lemoine-Goumard, M.
    Li, J.
    Li, Liang
    Longo, F.
    Loparco, F.
    Lovellette, M. N.
    Lubrano, P.
    Magill, J.
    Maldera, S.
    Marelli, M.
    Mayer, M.
    Mazziotta, M. N.
    Michelson, P. F.
    Mitthumsiri, W.
    Mizuno, T.
    Moiseev, A. A.
    Monzani, M. E.
    Moretti, E.
    Morselli, A.
    Moskalenko, I. V.
    Murgia, S.
    Nemmen, R.
    Nuss, E.
    Ohsugi, T.
    Omodei, N.
    Orienti, M.
    Orlando, E.
    Ormes, J. F.
    Paneque, D.
    Perkins, J. S.
    Pesce-Rollins, M.
    Petrosian, V.
    Piron, F.
    Pivato, G.
    Porter, T. A.
    Raino, S.
    Rando, R.
    Razzano, M.
    Razzaque, S.
    Reimer, A.
    Reimer, O.
    Renaud, M.
    Reposeur, T.
    Rousseau, R.
    Parkinson, P. M. Saz
    Schmid, J.
    Schulz, A.
    Sgro, C.
    Siskind, E. J.
    Spada, F.
    Spandre, G.
    Spinelli, P.
    Strong, A. W.
    Suson, D. J.
    Tajima, H.
    Takahashi, H.
    Tanaka, T.
    Thayer, J. B.
    Thompson, D. J.
    Tibaldo, L.
    Tibolla, O.
    Torres, D. F.
    Tosti, G.
    Troja, E.
    Uchiyama, Y.
    Vianello, G.
    Wells, B.
    Wood, K. S.
    Wood, M.
    Yassine, M.
    den Hartog, P. R.
    Zimmer, Stephan
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    THE FIRST FERMI LAT SUPERNOVA REMNANT CATALOG2016In: Astrophysical Journal Supplement Series, ISSN 0067-0049, E-ISSN 1538-4365, Vol. 224, no 1, article id 8Article in journal (Refereed)
    Abstract [en]

    To uniformly determine the properties of supernova remnants (SNRs) at high energies, we have developed the first systematic survey at energies from 1 to 100 GeV using data from the Fermi Large Area Telescope (LAT). Based on the spatial overlap of sources detected at GeV energies with SNRs known from radio surveys, we classify 30 sources as likely GeV SNRs. We also report 14 marginal associations and 245 flux upper limits. A mock catalog in which the positions of known remnants are scrambled in Galactic longitude allows us to determine an upper limit of 22% on the number of GeV candidates falsely identified as SNRs. We have also developed a method to estimate spectral and spatial systematic errors arising from the diffuse interstellar emission model, a key component of all Galactic Fermi LAT analyses. By studying remnants uniformly in aggregate, we measure the GeV properties common to these objects and provide a crucial context for the detailed modeling of individual SNRs. Combining our GeV results with multiwavelength (MW) data, including radio, X-ray, and TeV, we demonstrate the need for improvements to previously sufficient, simple models describing the GeV and radio emission from these objects. We model the GeV and MW emission from SNRs in aggregate to constrain their maximal contribution to observed Galactic cosmic rays.

  • 974. Acero, F.
    et al.
    Aharonian, F.
    Akhperjanian, A. G.
    Anton, G.
    de Almeida, U. Barres
    Bazer-Bachi, A. R.
    Becherini, Y.
    Behera, B.
    Bernloehr, K.
    Bochow, A.
    Boisson, C.
    Bolmont, J.
    Borrel, V.
    Braun, I.
    Brucker, J.
    Brun, F.
    Brun, P.
    Buehler, R.
    Bulik, T.
    Buesching, I.
    Boutelier, T.
    Chadwick, P. M.
    Charbonnier, A.
    Chaves, R. C. G.
    Cheesebrough, A.
    Conrad, Jan
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Chounet, L. -M
    Clapson, A. C.
    Coignet, G.
    Dalton, M.
    Daniel, M. K.
    Davids, I. D.
    Degrange, B.
    Deil, C.
    Dickinson, H. J.
    Djannati-Atai, A.
    Domainko, W.
    Drury, L. O 'C.
    Dubois, F.
    Dubus, G.
    Dyks, J.
    Dyrda, M.
    Egberts, K.
    Eger, P.
    Espigat, P.
    Fallon, L.
    Farnier, C.
    Fegan, S.
    Feinstein, F.
    Fiasson, A.
    Foerster, A.
    Fontaine, G.
    Fuessling, M.
    Gabici, S.
    Gallant, Y. A.
    Gerard, L.
    Gerbig, D.
    Giebels, B.
    Glicenstein, J. F.
    Glueck, B.
    Goret, P.
    Goering, D.
    Hauser, M.
    Heinz, S.
    Heinzelmann, G.
    Henri, G.
    Hermann, G.
    Hinton, J. A.
    Hoffmann, A.
    Hofmann, W.
    Hofverberg, P.
    Holleran, M.
    Hoppe, S.
    Horns, D.
    Jacholkowska, A.
    de Jager, O. C.
    Jahn, C.
    Jung, I.
    Katarzynski, K.
    Katz, U.
    Kaufmann, S.
    Kerschhaggl, M.
    Khangulyan, D.
    Khelifi, B.
    Keogh, D.
    Klochkov, D.
    Kluzniak, W.
    Kneiske, T.
    Komin, Nu.
    Kosack, K.
    Kossakowski, R.
    Lamanna, G.
    Lenain, J. -P
    Lohse, T.
    Marandon, V.
    Martineau-Huynh, O.
    Marcowith, A.
    Masbou, J.
    Maurin, D.
    McComb, T. J. L.
    Medina, M. C.
    Mehault, J.
    Moderski, R.
    Moulin, E.
    Naumann-Godo, M.
    de Naurois, M.
    Nedbal, D.
    Nekrassov, D.
    Nicholas, B.
    Niemiec, J.
    Nolan, S. J.
    Ohm, S.
    Olive, J-F
    Wilhelmi, E. de Ona
    Orford, K. J.
    Ostrowski, M.
    Panter, M.
    Arribas, M. Paz
    Pedaletti, G.
    Pelletier, G.
    Petrucci, P. -O
    Pita, S.
    Puehlhofer, G.
    Punch, M.
    Quirrenbach, A.
    Raubenheimer, B. C.
    Raue, M.
    Rayner, S. M.
    Reimer, O.
    Renaud, M.
    Rieger, F.
    Ripken, Joachim
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Rob, L.
    Rosier-Lees, S.
    Rowell, G.
    Rudak, B.
    Rulten, C. B.
    Ruppel, J.
    Ryde, F.
    Sahakian, V.
    Santangelo, A.
    Schlickeiser, R.
    Schoeck, F. M.
    Schoenwald, A.
    Schwanke, U.
    Schwarzburg, S.
    Schwemmer, S.
    Shalchi, A.
    Sikora, M.
    Skilton, J. L.
    Sol, H.
    Stawarz, L.
    Steenkamp, R.
    Stegmann, C.
    Stinzing, F.
    Superina, G.
    Sushch, I.
    Szostek, A.
    Tam, P. H.
    Tavernet, J. -P
    Terrier, R.
    Tibolla, O.
    Tluczykont, M.
    van Eldik, C.
    Vasileiadis, G.
    Venter, C.
    Venter, L.
    Vialle, J. P.
    Vincent, P.
    Vivier, M.
    Voelk, H. J.
    Volpe, F.
    Wagner, S. J.
    Ward, M.
    Zdziarski, A. A.
    Zech, A.
    Localizing the VHE gamma-ray source at the Galactic Centre2010In: Monthly notices of the Royal Astronomical Society, ISSN 0035-8711, E-ISSN 1365-2966, Vol. 402, no 3, p. 1877-1882Article in journal (Refereed)
    Abstract [en]

    The inner 10 pc of our Galaxy contains many counterpart candidates of the very high energy (VHE; > 100 GeV) gamma-ray point source HESS J1745-290. Within the point spread function of the H.E.S.S. measurement, at least three objects are capable of accelerating particles to VHE and beyond and of providing the observed gamma-ray flux. Previous attempts to address this source confusion were hampered by the fact that the projected distances between these objects were of the order of the error circle radius of the emission centroid (34 arcsec, dominated by the pointing uncertainty of the H.E.S.S. instrument). Here we present H.E.S.S. data of the Galactic Centre region, recorded with an improved control of the instrument pointing compared to H.E.S.S. standard pointing procedures. Stars observed during gamma-ray observations by optical guiding cameras mounted on each H.E.S.S. telescope are used for off-line pointing calibration, thereby decreasing the systematic pointing uncertainties from 20 to 6 arcsec per axis. The position of HESS J1745-290 is obtained by fitting a multi-Gaussian profile to the background-subtracted gamma-ray count map. A spatial comparison of the best-fitting position of HESS J1745-290 with the position and morphology of candidate counterparts is performed. The position is, within a total error circle radius of 13 arcsec, coincident with the position of the supermassive black hole Sgr A* and the recently discovered pulsar wind nebula candidate G359.95-0.04. It is significantly displaced from the centroid of the supernova remnant Sgr A East, excluding this object with high probability as the dominant source of the VHE gamma-ray emission.

  • 975. Acero, F.
    et al.
    Aharonian, F.
    Akhperjanian, A. G.
    Anton, G.
    de Almeida, U. Barres
    Bazer-Bachi, A. R.
    Becherini, Y.
    Behera, B.
    Bernloehr, K.
    Bochow, A.
    Boisson, C.
    Bolmont, J.
    Borrel, V.
    Brucker, J.
    Brun, F.
    Brun, P.
    Bulik, T.
    Buesching, I.
    Boutelier, T.
    Chadwick, P. M.
    Charbonnier, A.
    Chaves, R. C. G.
    Cheesebrough, A.
    Conrad, Jan
    Stockholm University, Faculty of Science, Department of Physics.
    Chounet, L. -M
    Clapson, A. C.
    Coignet, G.
    Dalton, M.
    Daniel, M. K.
    Davids, I. D.
    Degrange, B.
    Deil, C.
    Dickinson, H. J.
    Djannati-Atai, A.
    Domainko, W.
    Drury, L. O 'C.
    Dubois, F.
    Dubus, G.
    Dyks, J.
    Dyrda, M.
    Egberts, K.
    Eger, P.
    Espigat, P.
    Fallon, L.
    Farnier, C.
    Fegan, S.
    Feinstein, F.
    Fiasson, A.
    Foerster, A.
    Fontaine, G.
    Fuessling, M.
    Gabici, S.
    Gallant, Y. A.
    Gerard, L.
    Gerbig, D.
    Giebels, B.
    Glicenstein, J. F.
    Glueck, B.
    Goret, P.
    Goering, D.
    Hauser, M.
    Heinz, S.
    Heinzelmann, G.
    Henri, G.
    Hermann, G.
    Hinton, J. A.
    Hoffmann, A.
    Hofmann, W.
    Hofverberg, P.
    Holleran, M.
    Hoppe, S.
    Horns, D.
    Jacholkowska, A.
    de Jager, O. C.
    Jahn, C.
    Jung, I.
    Katarzynski, K.
    Katz, U.
    Kaufmann, S.
    Kerschhaggl, M.
    Khangulyan, D.
    Khelifi, B.
    Keogh, D.
    Klochkov, D.
    Kluzniak, W.
    Kneiske, T.
    Komin, Nu.
    Kosack, K.
    Kossakowski, R.
    Lamanna, G.
    Lenain, J. -P
    Lohse, T.
    Marandon, V.
    Marcowith, A.
    Masbou, J.
    Maurin, D.
    McComb, T. J. L.
    Medina, M. C.
    Mehault, J.
    Moderski, R.
    Moulin, E.
    Naumann-Godo, M.
    de Naurois, M.
    Nedbal, D.
    Nekrassov, D.
    Nicholas, B.
    Niemiec, J.
    Nolan, S. J.
    Ohm, S.
    Olive, J-F
    Wilhelmi, E. de Ona
    Orford, K. J.
    Ostrowski, M.
    Panter, M.
    Arribas, M. Paz
    Pedaletti, G.
    Pelletier, G.
    Petrucci, P. -O
    Pita, S.
    Puehlhofer, G.
    Punch, M.
    Quirrenbach, A.
    Raubenheimer, B. C.
    Raue, M.
    Rayner, S. M.
    Reimer, O.
    Renaud, M.
    de los Reyes, R.
    Rieger, F.
    Ripken, Joachim
    Stockholm University, Faculty of Science, Department of Physics.
    Rob, L.
    Rosier-Lees, S.
    Rowell, G.
    Rudak, B.
    Rulten, C. B.
    Ruppel, J.
    Ryde, F.
    Sahakian, V.
    Santangelo, A.
    Schlickeiser, R.
    Schoeck, F. M.
    Schoenwald, A.
    Schwanke, U.
    Schwarzburg, S.
    Schwemmer, S.
    Shalchi, A.
    Sushch, I.
    Sikora, M.
    Skilton, J. L.
    Sol, H.
    Stawarz, L.
    Steenkamp, R.
    Stegmann, C.
    Stinzing, F.
    Superina, G.
    Szostek, A.
    Tam, P. H.
    Tavernet, J. -P
    Terrier, R.
    Tibolla, O.
    Tluczykont, M.
    van Eldik, C.
    Vasileiadis, G.
    Venter, C.
    Venter, L.
    Vialle, J. P.
    Vincent, P.
    Vivier, M.
    Voelk, H. J.
    Volpe, F.
    Vorobiov, S.
    Wagner, S. J.
    Ward, M.
    Zdziarski, A. A.
    Zech, A.
    HESS upper limits on very high energy gamma-ray emission from the microquasar GRS 1915+1052009In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 508, no 3, p. 1135-1140Article in journal (Refereed)
    Abstract [en]

    Context. High energy particles reside in the relativistic jets of microquasars, making them possible sources of very high energy radiation (VHE, > 100 GeV). Detecting this emission would provide a new handle on jet physics. Aims. Observations of the microquasar GRS 1915+105 with the HESS telescope array were undertaken in 2004-2008 to search for VHE emission. Methods. Stereoscopic imaging of Cherenkov radiation from extensive air showers is used to reconstruct the energy and direction of the incident gamma rays. Results. There is no evidence for a VHE gamma-ray signal either from the direction of the microquasar or its vicinity. An upper limit of 6.1 x 10(-13) ph cm(-2) s(-1) (99.9% confidence level) is set on the photon flux above 410 GeV, equivalent to a VHE luminosity of similar to 10(34) erg s(-1) at 11 kpc. Conclusions. The VHE to X-ray luminosity ratio in GRS 1915+105 is at least four orders of magnitude lower than the ratio observed in gamma-ray binaries. The VHE radiative efficiency of the compact jet is less than 0.01% based on its estimated total power of 10(38) erg s(-1). Particle acceleration in GRS 1915+105 is not efficient at high energies and/or the magnetic field is too strong. It is also possible that VHE gamma-rays are produced by GRS 1915+105, but the emission is highly time-dependent.

  • 976. Acero, F.
    et al.
    Wagner, Robert
    Stockholm University, Faculty of Science, Department of Physics. Max-Planck-Institut für Physik, Germany.
    Zorn, J.
    Prospects for Cherenkov Telescope Array Observations of the Young Supernova Remnant RX J1713.7-39462017In: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 840, no 2, article id 74Article in journal (Refereed)
    Abstract [en]

    We perform simulations for future Cherenkov Telescope Array (CTA) observations of RX J1713.7-3946, a young supernova remnant (SNR) and one of the brightest sources ever discovered in very high energy (VHE) gamma rays. Special attention is paid to exploring possible spatial (anti) correlations of gamma rays with emission at other wavelengths, in particular X-rays and CO/H I emission. We present a series of simulated images of RX J1713.7-3946 for CTA based on a set of observationally motivated models for the gamma-ray emission. In these models, VHE gamma rays produced by high-energy electrons are assumed to trace the nonthermal X-ray emission observed by XMM-Newton, whereas those originating from relativistic protons delineate the local gas distributions. The local atomic and molecular gas distributions are deduced by the NANTEN team from CO and H I observations. Our primary goal is to show how one can distinguish the emission mechanism(s) of the gamma rays (i.e., hadronic versus leptonic, or a mixture of the two) through information provided by their spatial distribution, spectra, and time variation. This work is the first attempt to quantitatively evaluate the capabilities of CTA to achieve various proposed scientific goals by observing this important cosmic particle accelerator.

  • 977. Aceto, Luca
    et al.
    Della Monica, Dario
    Goranko, Valentin
    Stockholm University, Faculty of Humanities, Department of Philosophy. University of Johannesburg, South Africa.
    Ingólfsdóttir, Anna
    Montanari, Angelo
    Sciavicco, Guido
    A complete classification of the expressiveness of interval logics of Allen’s relations: the general and the dense cases2016In: Acta Informatica, ISSN 0001-5903, E-ISSN 1432-0525, Vol. 53, no 3, p. 207-246Article in journal (Refereed)
    Abstract [en]

    Interval temporal logics take time intervals, instead of time points, as their primitive temporal entities. One of the most studied interval temporal logics is Halpern and Shoham’s modal logic of time intervals HS, which associates a modal operator with each binary relation between intervals over a linear order (the so-called Allen’s interval relations). In this paper, we compare and classify the expressiveness of all fragments of HS on the class of all linear orders and on the subclass of all dense linear orders. For each of these classes, we identify a complete set of definabilities between HS modalities, valid in that class, thus obtaining a complete classification of the family of all 4096 fragments of HS with respect to their expressiveness. We show that on the class of all linear orders there are exactly 1347 expressively different fragments of HS, while on the class of dense linear orders there are exactly 966 such expressively different fragments.

  • 978.
    Acevedo Belmonte, Rebecca
    et al.
    Stockholm University, Faculty of Social Sciences, School of Business.
    Ronnevi, Therese
    Stockholm University, Faculty of Social Sciences, School of Business.
    Corporate Citizenship2002Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    I samhällsdebatten tycker vi oss märka ett tilltagande intresse och en ökande efterfråga för ett större socialt engagemang och ansvarstagande av företagen. Det är framför allt affärs- och företagsetiken som kommit i fokus och frågor som rör västvärldens och storföretagens utnyttjande av exempelvis lågavlönad arbetskraft, fattiga länders bristfälliga lagar m m. Det handlar om corporate citizenship, företagen som medborgare och deras sociala ansvar gentemot de samhälle de verkar i.

  • 979. Acevedo, Nathalie
    et al.
    Bornacelly, Adriana
    Mercado, Dilia
    Unneberg, Per
    Stockholm University, Science for Life Laboratory (SciLifeLab). Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Mittermann, Irene
    Valenta, Rudolf
    Kennedy, Malcolm
    Scheynius, Annika
    Caraballo, Luis
    Genetic Variants in CHIA and CHI3L1 Are Associated with the IgE Response to the Ascaris Resistance Marker ABA-1 and the Birch Pollen Allergen Bet v 12016In: plos one, ISSN 1932-6203, Vol. 11, no 12, article id e0167453Article in journal (Refereed)
    Abstract [en]

    Helminth infections and allergic diseases are associated with IgE hyperresponsiveness but the genetics of this phenotype remain to be defined. Susceptibility to Ascaris lumbricoides infection and antibody levels to this helminth are associated with polymorphisms in locus 13q33-34. We aimed to explore this and other genomic regions to identify genetic variants associated with the IgE responsiveness in humans. Forty-eight subjects from Cartagena, Colombia, with extreme values of specific IgE to Ascaris and ABA-1, a resistance marker of this nematode, were selected for targeted resequencing. Burden analyses were done comparing extreme groups for IgE values. One-hundred one SNPs were genotyped in 1258 individuals of two well-characterized populations from Colombia and Sweden. Two low-frequency coding variants in the gene encoding the Acidic Mammalian Chitinase (CHIA rs79500525, rs139812869, tagged by rs10494133) were found enriched in high IgE responders to ABA-1 and confirmed by genetic association analyses. The SNP rs4950928 in the Chitinase 3 Like 1 gene (CHI3L1) was associated with high IgE to ABA-1 in Colombians and with high IgE to Bet v 1 in the Swedish population. CHIA rs10494133 and ABDH13 rs3783118 were associated with IgE responses to Ascaris. SNPs in the Tumor Necrosis Factor Superfamily Member 13b gene (TNFSF13B) encoding the cytokine B cell activating Factor were associated with high levels of total IgE in both populations. This is the first report on the association between low-frequency and common variants in the chitinases- related genes CHIA and CHI3L1 with the intensity of specific IgE to ABA-1 in a population naturally exposed to Ascaris and with Bet v 1 in a Swedish population. Our results add new information about the genetic influences of human IgE responsiveness; since the genes encode for enzymes involved in the immune response to parasitic infections, they could be helpful for understanding helminth immunity and allergic responses. We also confirmed that TNFSF13B has an important and conserved role in the regulation of total IgE levels, which supports potential evolutionary links between helminth immunity and allergic response.

  • 980. Achari, Muthuraaman Bhagavathi
    et al.
    Elumalai, Viswanathan
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Vlachopoulos, Nick
    Safdari, Majid
    Gao, Jiajia
    Gardner, James M.
    Kloo, Lars
    A quasi-liquid polymer-based cobalt redox mediator electrolyte for dye-sensitized solar cells2013In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 15, no 40, p. 17419-17425Article in journal (Refereed)
    Abstract [en]

    Recently, cobalt redox electrolyte mediators have emerged as a promising alternative to the commonly used iodide/triiodide redox shuttle in dye-sensitized solar cells (DSCs). Here, we report the successful use of a new quasi-liquid, polymer-based electrolyte containing the Co3+/Co2+ redox mediator in 3-methoxy propionitrile solvent in order to overcome the limitations of high cell resistance, low diffusion coefficient and rapid recombination losses. The performance of the solar cells containing the polymer based electrolytes increased by a factor of 1.2 with respect to an analogous electrolyte without the polymer. The performances of the fabricated DSCs have been investigated in detail by photovoltaic, transient electron measurements, EIS, Raman and UV-vis spectroscopy. This approach offers an effective way to make high-performance and long-lasting DSCs.

  • 981. Acharya, B.
    et al.
    Alexandre, J.
    Bendtz, Katarina
    Stockholm University, Faculty of Science, Department of Physics.
    Benes, P.
    Bernabeu, J.
    Campbell, M.
    Cecchini, S.
    Chwastowski, J.
    Chatterjee, A.
    de Montigny, M.
    Derendarz, D.
    De Roeck, A.
    Ellis, J. R.
    Fairbairn, M.
    Felea, D.
    Frank, M.
    Frekers, D.
    Garcia, C.
    Giacomelli, G.
    Hasegan, D.
    Kalliokoski, M.
    Katre, A.
    Kim, D. -W.
    King, M. G. L.
    Kinoshita, K.
    Lacarrere, D. H.
    Lee, S. C.
    Leroy, C.
    Lionti, A.
    Margiotta, A.
    Mauri, N.
    Mavromatos, N. E.
    Mermod, P.
    Milstead, David A.
    Stockholm University, Faculty of Science, Department of Physics.
    Mitsou, V. A.
    Orava, R.
    Parker, B.
    Pasqualini, L.
    Patrizii, L.
    Pavalas, G. E.
    Pinfold, J. L.
    Platkevic, M.
    Popa, V.
    Pozzato, M.
    Pospisil, S.
    Rajantie, A.
    Sahnoun, Z.
    Sakellariadou, M.
    Sarkar, S.
    Stemenoff, G.
    Sirri, G.
    Silwa, K.
    Soluk, R.
    Spurio, M.
    Srivastava, Y. N.
    Staszewski, R.
    Suk, M.
    Swain, J.
    Tenti, M.
    Togo, V.
    Trzebinski, M.
    Tuszynski, J. A.
    Vento, V.
    Vives, O.
    Vykdal, Z.
    Whyntie, T.
    Widom, A.
    Willems, G.
    Yoon, J. H.
    Search formagnetic monopoles with the MoEDAL prototype trapping detector in 8 TeV proton-proton collisions at the LHC2016In: Journal of High Energy Physics (JHEP), ISSN 1126-6708, E-ISSN 1029-8479, no 8, article id 067Article in journal (Refereed)
    Abstract [en]

    The MoEDAL experiment is designed to search for magnetic monopoles and other highly-ionising particles produced in high-energy collisions at the LHC. The largely passive MoEDAL detector, deployed at Interaction Point 8 on the LHC ring, relies on two dedicated direct detection techniques. The first technique is based on stacks of nuclear-track detectors with surface area similar to 18 m(2), sensitive to particle ionisation exceeding a high threshold. These detectors are analysed offline by optical scanning microscopes. The second technique is based on the trapping of charged particles in an array of roughly 800 kg of aluminium samples. These samples are monitored offline for the presence of trapped magnetic charge at a remote superconducting magnetometer facility. We present here the results of a search for magnetic monopoles using a 160 kg prototype MoEDAL trapping detector exposed to 8TeV proton-proton collisions at the LHC, for an integrated luminosity of 0.75 fb(-1). No magnetic charge exceeding 0.5g(D) (where g(D) is the Dirac magnetic charge) is measured in any of the exposed samples, allowing limits to be placed on monopole production in the mass range 100 GeV <= m <= 3500 GeV. Model-independent cross-section limits are presented in fiducial regions of monopole energy and direction for 1g(D) <= vertical bar g vertical bar <= 6g(D), and model-dependent cross-section limits are obtained for Drell-Yan pair production of spin-1/2 and spin-0 monopoles for 1g(D) <= vertical bar g vertical bar <= 4g(D). Under the assumption of Drell-Yan cross sections, mass limits are derived for vertical bar g vertical bar = 2g(D) and vertical bar g vertical bar = 3g(D) for the first time at the LHC, surpassing the results from previous collider experiments.

  • 982. Acharya, Kamal Prasad
    et al.
    De Frenne, Pieter
    Brunet, Jörg
    Chabrerie, Olivier
    Cousins, Sara A. O.
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Diekmann, Martin
    Hermy, Martin
    Kolb, Annette
    Lemke, Isgard
    Plue, Jan
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Verheyen, Kris
    Graae, Bente Jessen
    Latitudinal variation of life-history traits of an exotic and a native impatiens species in Europe2017In: Acta Oecologica, ISSN 1146-609X, E-ISSN 1873-6238, Vol. 81, p. 40-47Article in journal (Refereed)
    Abstract [en]

    Understanding the responses of invasive and native populations to environmental change is crucial for reliable predictions of invasions in the face of global change. While comparisons of responses across invasive species with different life histories have been performed before, comparing functional traits of congeneric native and invasive species may help to reveal driving factors associated with invasion. Here we compared morphological functional trait patterns of an invasive species (Impatiens parviflora) with its congeneric native species (I. noli-tangere) along an approximately 1600 km European latitudinal gradient from France (49 degrees 34'N) to Norway (63 degrees 40'N). Soil nitrogen was recorded during six weeks of the growing season, and light, soil moisture, and nutrient availability were estimated for each sampled population using community weighted means of indicator values for co-occurring species. Temperature data were gathered from nearby weather stations. Both the native and invasive species are taller at higher latitudes and this response is strongest in the invasive species. Seed mass and number of seeds per capsule increase in I. noli-tangere but decrease in I. parviflora towards higher latitudes. Surprisingly, plant height in the invasive I. parviflora decreases with increasing soil nitrogen availability. The latitudinal pattern in seed mass is positively related to temperature in I. noli-tangere and negatively in I. parviflora. Leaf area of both species decreases with increasing Ellenberg indicator values for nitrogen and light but increases with increasing soil moisture. Soil nitrogen concentrations and Ellenberg indicator values for nitrogen have significant positive (I. nolitangere) and negative (I. parviflora) effects on the number of seeds per capsule. Our results show that the native I. noli-tangere has efficient reproduction at its range edge while the invasive I. parviflora shows a marked decrease in seed size and seed number per capsule. These patterns are unrelated to the growth and obtained size of the plants: even low soil nitrogen availability in the north seemed not to limit plant growth and size. Our results suggest that the invasive I. parviflora tends to become more invasive at lower latitudes by producing heavier seeds and more seeds per capsule.

  • 983. Acher, Andrés
    et al.
    Krabbe Sillasen, Martin
    Febri, Maria I. M.
    Lyngved Staberg, Ragnhild
    Karlström, Matti
    Stockholm University, Faculty of Science, Department of Mathematics and Science Education.
    Hamza, Karim
    Stockholm University, Faculty of Science, Department of Mathematics and Science Education.
    McDonald, Scott
    Teaching Practices in Preservice Science Teacher Education2018In: Electronic Proceedings of the ESERA 2017 Conference: Research, Practice and Collaboration in Science Education / [ed] Odilla Finlayson, Eilish McLoughlin, Sibel Erduran, Peter Childs, Dublin, Ireland: Dublin City University , 2018, p. 1903-1914Conference paper (Refereed)
    Abstract [en]

    Recent efforts to design and study Pre-service Science Teacher Education have focused on engaging future teachers in teaching practices. This focus on practices comes with an explicit intention to blend aspects of knowledge and doing that has been historically separate in other efforts to teach novice learners practical aspects of their profession. This intention brings particular challenges to EU preservice teacher preparation programs that need to reconsider how to incorporate aspects of practices into their science education courses. These challenges not only emerge from the novelty and interrelated nature of these practices, but also from lack of clear ways of articulating what these practices are and look like across international teacher educational contexts. This paper brings together four EU studies and an international discussant that explore possibilities to embrace and respond to these challenges and being a cross-contextual conversation about science teacher education. 

  • 984. Achidi, E. A.
    et al.
    Apinjoh, T. O.
    Mbunwe, E.
    Besingi, R.
    Yafi, C.
    Awah, N. Wenjighe
    Stockholm University, Faculty of Science, The Wenner-Gren Institute , Immunology.
    Ajua, A.
    Anchang, J. K.
    Febrile status, malarial parasitaemia and gastro-intestinal helminthiases in schoolchildren resident at different altitudes, in south-western Cameroon2008In: Annals of Tropical Medicine and Parasitology, ISSN 0003-4983, E-ISSN 1364-8594, Vol. 102, no 2, p. 103-118Article in journal (Refereed)
    Abstract [en]

    In the many areas where human malaria and helminthiases are co-endemic, schoolchildren often harbour the heaviest infections and suffer much of the associated morbidity, especially when co-infected. In one such area, the Buea district, in south-western Cameroon, two cross-sectional surveys, together covering 263 apparently healthy schoolchildren aged 4-12 years, were recently conducted. The prevalences of fever, malarial parasitaemia and intestinal helminth infections, the seroprevalences of anti-Plasmodium falciparum IgG and IgE and anti-glycosylphosphatidylinositol (anti-GPI) IgG, plasma concentrations of total IgE, and the incidence of anaemia were all investigated. The mean (S.D.) age of the study children was 7.56 (1.82) years. Overall, 156 (59.3%) of the children were found parasitaemic, with a geometric mean parasitaemia of 565 parasites/mu l. Parasitaemia and fever were significantly associated (P=0.042). The children who lived at low altitude, attending schools that lay 400-650 m above sea level, had significantly higher parasitaemias than their high-altitude counterparts (P < 0.01). At low altitude, the children attending government schools had significantly higher parasitaemias than their mission-school counterparts (P=0.010). Of the 31 children (11.9%) found anaemic, 22 (70.4%) had mild anaemia and none had severe anaemia. A significant negative correlation (r=-0.224; P=0.005) was observed between haemoglobin concentration and level of parasitaemia. Infection with Plasmodium appeared to reduce erythrocyte counts (P=0.045), a condition that was exacerbated by co-infection with helminths (P=0.035). Plasma concentrations of total IgE were higher in the children found to be excreting helminth eggs than in those who appeared helminth-free, while levels of anti-P. falciparum IgE were higher in the children with low-grade parasitaemias than in those with more intense parasitaemias. Levels of anti-GPI IgG increased with age and were relatively high in the children who lived at low altitude and in those who were aparasitaemic. The survey results confirm that asymptomatic malarial parasitaemia frequently co-exists with helminth infections in schoolchildren and indicate links with fever, altitude and school type. Immunoglobulin E may play a role in immune protection against helminthiasis whereas anti-GPI antibodies may be important in the development of antimalarial immunity in such children. In Cameroon, as in other areas with endemic malaria, control programmes to reduce the prevalences of infections with intestinal helminths and malarial parasites in schoolchildren, which may effectively reduce the incidence of anaemia, are clearly needed.

  • 985.
    Achimo, Mussa
    Stockholm University.
    Sedimentology and geochemistry of the recent sediments in Maputo Bay, Mozambique2002Doctoral thesis, comprehensive summary (Other academic)
  • 986. Achnak, Safâa
    et al.
    Griep, Yannick
    Stockholm University, Faculty of Social Sciences, Stress Research Institute. University of Calgary, Canada.
    Vantilborgh, Tim
    I Am So Tired... How Fatigue May Exacerbate Stress Reactions to Psychological Contract Breach2018In: Frontiers in Psychology, ISSN 1664-1078, E-ISSN 1664-1078, Vol. 9, article id 231Article in journal (Refereed)
    Abstract [en]

    Previous research showed that perceptions of psychological contract (PC) breach have undesirable individual and organizational consequences. Surprisingly, the PC literature has paid little to no attention to the relationship between PC breach perceptions and stress. A better understanding of how PC breach may elicit stress seems crucial, given that stress plays a key role in employees' physical and mental well-being. Based on Conservation of Resources Theory, we suggest that PC breach perceptions represent a perceived loss of valued resources, subsequently leading employees to experience higher stress levels resulting from emerging negative emotions. Moreover, we suggest that this mediated relationship is moderated by initial levels of fatigue, due to fatigue lowering the personal resources necessary to cope with breach events. To tests our hypotheses, we analyzed the multilevel data we obtained from two experience sampling designs (Study 1: 51 Belgian employees; Study 2: 53 US employees). Note that the unit of analysis is observations rather than respondents, resulting in an effective sample size of 730 (Study 1) and 374 (Study 2) observations. In both studies, we found evidence for the mediating role of negative emotions in the PC breach-stress relationship. In the second study, we also found evidence for the moderating role of fatigue in the mediated PC breach-stress relationship. Implications for research and practice are discussed.

  • 987. Achterberg et al., IceCube Collaboration: A
    Detection of Atmospheric Muon Neutrinos with the IcCube 9-String Detector2007Article in journal (Refereed)
  • 988. Achterberg et al., IceCube Collaboration: A
    First Year Performance of the Icecube Neutrino Telescope2006In: Astroparticle Physics, Vol. 26, p. 155-Article in journal (Refereed)
  • 989. Achterberg et al., IceCube Collaboration: A
    Limits on the High-Energy Gamma and Neutrino Fluxes from the SGR 1806-20 Giant Flare of 27 December2004 with the AMANDA-II Detector2006In: Physical Review Letters, Vol. 97, p. 221101-Article in journal (Refereed)
  • 990. Achterberg et al., IceCube Collaboration: A
    Limits on the Muon Flux from Neutralino Annihilations at the Center of the Earth with AMANDA2006In: Astroparticle Physics, Vol. 26, p. 129-Article in journal (Refereed)
  • 991. Achterberg et al., IceCube Collaboration: A
    Multiyear Search for a Diffuse Flux of Muon Neutrinos with AMANDA-II2007In: Physical Review D, Vol. 76, p. 042008-Article in journal (Refereed)
  • 992. Achterberg et al., IceCube Collaboration: A
    On the Selection of AGN Neutrino Source Candidates for a Source Stacking Analysis with Neutrino Telescopes2006In: Astroparticle Physics, Vol. 26, p. 282-Article in journal (Refereed)
  • 993. Achterberg et al., IceCube Collaboration: A
    Search for Neutrino-InducedCascades From Gamma-Ray Bursts with AMANDA2007In: The Astrophysical Journal, Vol. 664, p. 397-Article in journal (Refereed)
  • 994. Achtert, P.
    et al.
    Brooks, I. M.
    Brooks, B. J.
    Moat, B. I.
    Prytherch, J.
    Persson, P. O. G.
    Tjernström, Michael
    Stockholm University, Faculty of Science, Department of Meteorology .
    Measurement of wind profiles by motion-stabilised ship-borne Doppler lidar2015In: Atmospheric Measurement Techniques, ISSN 1867-1381, E-ISSN 1867-8548, Vol. 8, no 11, p. 4993-5007Article in journal (Refereed)
    Abstract [en]

    Three months of Doppler lidar wind measurements were obtained during the Arctic Cloud Summer Experiment on the icebreakerOden during the summer of 2014. Such ship-borne Doppler measurements require active stabilisation to remove the effects of ship motion. We demonstrate that the combination of a commercial Doppler lidar with a custom-made motion-stabilisation platform enables the retrieval of wind profiles in the Arctic atmospheric boundary layer during both cruising and ice-breaking with statistical uncertainties comparable to land-based measurements. This held true particularly within the atmospheric boundary layer even though the overall aerosol load was very low. Motion stabilisation was successful for high wind speeds in open water and the resulting wave conditions. It allows for the retrieval of vertical winds with a random error below 0.2 m s−1. The comparison of lidar-measured wind and radio soundings gives a mean bias of 0.3 m s−1 (2°) and a mean standard deviation of 1.1 m s−1 (12°) for wind speed (wind direction). The agreement for wind direction degrades with height. The combination of a motion-stabilised platform with a low-maintenance autonomous Doppler lidar has the potential to enable continuous long-term high-resolution ship-based wind profile measurements over the oceans.

  • 995.
    Achtert, Peggy
    Stockholm University, Faculty of Science, Department of Meteorology .
    Lidar Measurements of Polar Stratospheric Clouds in the Arctic2013Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Polar Stratospheric Clouds (PSCs) play a key role for ozone depletion in the polar stratosphere. Its magnitude depends on the type of PSC and its lifetime and extent. This thesis presents PSC observations conducted with the Esrange lidar and the space-borne CALIPSO lidar.

    PSCs are separated into three types according to their optical properties. The occurrence rate of the different types which are often observed simultaneously as well as their interaction and connection is not well understood. To better understand the processes that govern PSC formation, observations need to be combined with a detailed view of the atmospheric background in which PSCs develop, exist, and are transformed from one type to another.

    This thesis introduces a new channel of the Esrange lidar for temperature profiling at heights below 35 km. The design of this channel and first temperature measurements within PSCs and cirrus clouds are presented. This is an important step since the majority of PSC-related literature extracts temperatures within PSCs from reanalysis data.

    In contrast to ground–based measurements space–borne lidar does not rely on cloud–free conditions. Hence, it provides an unprecedented opportunity for studying the connection between PSCs and the underlying synoptic–scale conditions which manifest as tropospheric clouds. This thesis shows that most of the PSCs observed in the Arctic during winter 2007/08 occurred in connection with tropospheric clouds.

    A combined analysis of ground-based and space-borne lidar observation of PSCs in combination with microphysical modeling can improve our understanding of PSC formation. A first case study of this approach shows how a PSC that was formed by synoptic-scale processes is transformed into another type while passing the Scandinavian mountains.

    Today a variety of classification schemes provides inconsistent information on PSC properties and types. This thesis suggests a unified classification scheme for lidar measurements of PSCs.

  • 996.
    Achtert, Peggy
    et al.
    Stockholm University, Faculty of Science, Department of Meteorology .
    Birmili, W.
    Nowak, A.
    Wehner, B.
    Wiedensohler, A.
    Takegawa, N.
    Kondo, Y.
    Miyazaki, Y.
    Hu, M.
    Zhu, T.
    Hygroscopic growth of tropospheric particle number size distributions over the North China Plain2009In: Journal of Geophysical Research, ISSN 0148-0227, E-ISSN 2156-2202, Vol. 114, p. D00G07-Article in journal (Refereed)
    Abstract [en]

    The hygroscopic growth of atmospheric submicrometer particle size distributions (diameter D-p ranging from 22 to 900 nm) was studied at a rural/suburban site in the North China Plain within the framework of the international Campaigns of Air Quality Research in Beijing and Surrounding Region 2006 (CAREBeijing-2006) research project. The goal was to characterize the regional aerosol in the polluted northeastern plain in China. Size descriptive hygroscopic growth factors (DHGFs) were determined as a function of relative humidity (RH) by relating the particle number size distribution at a dry condition ( 100 nm), the DHGF are substantially higher than in the Aitken particle mode (D-p < 100 nm) as a result of different chemical composition. The size-dependent behavior of the DHGF highlights the relevance of particulate sulfate production over the North China Plain, accomplished by secondary formation from the gas phase and, potentially, liquid phase processes in convective clouds. Furthermore, all results concerning the DHGF show a significant dependency on meteorological air masses. The hygroscopic growth of accumulation mode particles correlates significantly with the PM1-mass fraction of sulfate ions determined by chemical analysis. Finally, this investigation provides a parameterization of the hygroscopic growth of 250-nm particles, which might be useful when predicting visibility and radiative forcing and performing atmospheric aerosol model validations.

  • 997.
    Achtert, Peggy
    et al.
    Stockholm University, Faculty of Science, Department of Meteorology .
    Karlsson Andersson, M.
    Stockholm University, Faculty of Science, Department of Meteorology .
    Khosrawi, Farahnaz
    Stockholm University, Faculty of Science, Department of Meteorology .
    Gumbel, Jörg
    Stockholm University, Faculty of Science, Department of Meteorology .
    On the linkage between tropospheric and Polar Stratospheric clouds in the Arctic as observed by space-borne lidar2012In: Atmospheric Chemistry And Physics, ISSN 1680-7316, E-ISSN 1680-7324, Vol. 12, no 8, p. 3791-3798Article in journal (Refereed)
    Abstract [en]

    The type of Polar stratospheric clouds (PSCs) as well as their temporal and spatial extent are important for the occurrence of heterogeneous reactions in the polar stratosphere. The formation of PSCs depends strongly on temperature. However, the mechanisms of the formation of solid PSCs are still poorly understood. Recent satellite studies of Antarctic PSCs have shown that their formation can be associated with deep-tropospheric clouds which have the ability to cool the lower stratosphere radiatively and/or adiabatically. In the present study, lidar measurements aboard the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) satellite were used to investigate whether the formation of Arctic PSCs can be associated with deep-tropospheric clouds as well. Deep-tropospheric cloud systems have a vertical extent of more than 6.5 km with a cloud top height above 7 km altitude. PSCs observed by CALIPSO during the Arctic winter 2007/2008 were classified according to their type (STS, NAT, or ice) and to the kind of underlying tropospheric clouds. Our analysis reveals that 172 out of 211 observed PSCs occurred in connection with tropospheric clouds. 72% of these 172 observed PSCs occurred above deep-tropospheric clouds. We also find that the type of PSC seems to be connected to the characteristics of the underlying tropospheric cloud system. During the Arctic winter 2007/2008 PSCs consisting of ice were mainly observed in connection with deep-tropospheric cloud systems while no ice PSC was detected above cirrus. Furthermore, we find no correlation between the occurrence of PSCs and the top temperature of tropospheric clouds. Thus, our findings suggest that Arctic PSC formation is connected to adiabatice cooling, i.e. dynamic effects rather than radiative cooling.

  • 998.
    Achtert, Peggy
    et al.
    Stockholm University, Faculty of Science, Department of Meteorology .
    Khaplanov, Mikhail
    Stockholm University, Faculty of Science, Department of Meteorology .
    Khosrawi, Farahnaz
    Stockholm University, Faculty of Science, Department of Meteorology .
    Gumbel, Jörg
    Stockholm University, Faculty of Science, Department of Meteorology .
    Pure rotational-Raman channels of the Esrange lidar for temperature and particle extinction measurements in the troposphere and lower stratosphere2013In: Atmospheric Measurement Techniques, ISSN 1867-1381, E-ISSN 1867-8548, Vol. 6, no 1, p. 91-98Article in journal (Refereed)
    Abstract [en]

    The Department of Meteorology at Stockholm University operates the Esrange Rayleigh/Raman lidar at Esrange(68° N, 21° E) near the Swedish city of Kiruna. This paper describes the design and first measurements of the newpure rotational-Raman channel of the Esrange lidar. The Esrange lidar uses a pulsed Nd:YAG solid-state laser operating at 532 nm as light source with a repetition rate of 20 Hz and a pulse energy of 350 mJ. The minimum vertical resolution is 150m and the integration time for one profile is 5000 shots. The newly implemented channel allows for measurements of atmospheric temperature at altitudes below 35 km and is currently optimized for temperature measurements between 180 and 200 K. This corresponds to conditions in the lower Arctic stratosphere during winter. In addition to the temperature measurements, the aerosol extinction coefficientand the aerosol backscatter coefficient at 532 nm can be measured in dependently. Our filter-based design minimizes the systematic error in the obtained temperature profile to less than 0.51 K. By combining rotational-Raman measurements (5–35 km height) and the integration technique (30–80 kmheight), the Esrange lidar is now capable of measuring atmospheric temperature profiles from the upper troposphere up to the mesosphere. With the improved setup, the system can be used to validate current lidar-based polar stratospheric cloud classification schemes. The new capability of the instrument measuring temperature and aerosol extinction furthermore enables studies of the thermal structure and variability of the upper troposphere/lower stratosphere. Although several lidars are operated at polar latitudes, there are few instruments that are capable of measuring temperature profiles in the troposphere, stratosphere, and mesosphere, as well as aerosols extinction in the troposphere and lower stratospherewith daylight capability.

  • 999.
    Achtert, Peggy
    et al.
    Stockholm University, Faculty of Science, Department of Meteorology .
    Khosrawi, Farahnaz
    Stockholm University, Faculty of Science, Department of Meteorology .
    Blum, U.
    Fricke, K. H.
    Investigation of polar stratospheric clouds in January 2008 by means of ground-based and spaceborne lidar measurements and microphysical box model simulations2011In: Journal of Geophysical Research, ISSN 0148-0227, E-ISSN 2156-2202, Vol. 116, p. D07201-Article in journal (Refereed)
    Abstract [en]

    Polar stratospheric clouds (PSCs) play a key role in heterogeneous chemistry and ozone depletion in the lower stratosphere. The type of PSC as well as their temporal and spatial extent are important for the occurrence of heterogeneous reactions and, thus, ozone depletion. In this study a combination of ground-based and spaceborne lidar measurements were used together with microphysical box model simulations along back trajectories to investigate the formation and alteration of Arctic PSCs. The measurements were made by the Rayleigh/Mie/Raman lidar system at Esrange and by the Cloud-Aerosol Lidar with Orthogonal Polarization aboard the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) satellite. Between 20 and 23 January 2008 PSCs composed of liquid particles were observed by CALIPSO between Greenland and the western side of the Scandinavian Mountains. Between 21 and 23 January 2008 the Esrange lidar observed a PSC composed of distinct layers of liquid and solid particles on the eastern side of the mountain range. Microphysical box model simulations along air parcel back trajectories indicate that liquid particles had formed at least 40 h before the observation at Esrange. Furthermore, the model indicates a high HNO(3) uptake into the liquid layer between 10 and 20 h before the observation. The PSC was formed when the air mass was over Greenland. On two occasions during these 20 h, CALIPSO observed PSCs when its measurement tracks crossed the air parcel back trajectory ending at the location of the Esrange lidar. Backscatter ratios calculated from the output of the box model simulation indicate good agreement with the values observed with the Esrange lidar and by CALIPSO. The box model simulations along the back trajectories from Esrange to the CALIPSO ground track and beyond provide us with the unique opportunity to relate ground-based and spaceborne lidar measurements that were not performed at the same spatial location and time. Furthermore, possible differences in the observations from ground and space can be traced to temporal and/or geographically induced changes in particle microphysics within the measured PSCs.

  • 1000.
    Achtert, Peggy
    et al.
    Stockholm University, Faculty of Science, Department of Meteorology .
    Tesche, Matthias
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Assessing lidar-based classification schemes for polar stratospheric clouds based on 16 years of measurements at Esrange, Sweden2014In: Journal of Geophysical Research: Atmospheres, ISSN 2169-8996, Vol. 119, no 3, p. 1386-1405Article in journal (Refereed)
    Abstract [en]

    Lidar measurements of polar stratospheric clouds (PSCs) are commonly analyzed in classification schemes that apply the backscatter ratio and the particle depolarization ratio. This similarity of input data suggests comparable results of different classification schemes—despite measurements being performed with a variety of mostly custom-made instruments. Based on a time series of 16 years of lidar measurements at Esrange (68°N, 21°E), Sweden, we show that PSC classification differs substantially depending on the applied scheme. The discrepancies result from varying threshold values of lidar-derived parameters used to define certain PSC types. The resulting inconsistencies could impact the understanding of long-term PSC observations documented in the literature. We identify two out of seven considered classification schemes that are most likely to give reliable results and should be used in future lidar-based studies. Using polarized backscatter ratios gives the advantage of increased contrast for observations of weakly backscattering and weakly depolarizing particles. Improved confidence in PSC classification can be achieved by a more comprehensive consideration of the effect of measurement uncertainties. The particle depolarization ratio is the key to a reliable identification of different PSC types. Hence, detailed information on the calibration of the polarization-sensitive measurement channels should be provided to assess the findings of a study. Presently, most PSC measurements with lidar are performed at 532 nm only. The information from additional polarization-sensitive measurements in the near infrared could lead to an improved PSC classification. Coincident lidar-based temperature measurements at PSC level might provide useful information for an assessment of PSC classification.

17181920212223 951 - 1000 of 104615
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf