Designing by decorating: The use of pictures in primary school

Introduction. This paper concerns the concept of information use. The aim of the study is to understand how information use, as an activity, is shaped when project-based methods are used in primary school. The particular focus here is information use which involves visual information resources. It relates to the overarching aim of a set of studies describing and illustrating how information literacies are enacted and socially shaped in Swedish primary schools. Method. 25 booklets, produced by children at a Swedish primary school when working with project-based assignments, were collected during an ethnographical study. Analysis. An analysis of the relationships between pictures and text in the 25 booklets was conducted. Results. The analysis suggests that the pictures in the booklets are subordinated to written text and their functions are decorative and illustrative. Pictures are seldom used for explaining or narrating. Conclusions. An underpinning idea of the study is to understand information activities as purposeful within the settings where they take place. Given earlier research indicating that project-based working methods tend to be focused on the reproduction of facts and the making of products rather than on contents, it could be argued that the children's use of pictures in this study is purposeful. However, if this use of pictures is a desirable outcome could be a matter of discussion. The findings may be relevant for developing teaching in the multimodal aspects of information use

Constructing the Desirable Reader in Swedish Contemporary: Literature Policy

This study contributes to a growing number of critical studies of reading that are seeking to understand how reading is constructed socially and politically. It addresses issues concerning why certain types of reading are deemed more appropriate than others in various contexts and historical eras. The aim of the study is to explore constructions of reading, reading promotion, and readers that can be identified in Swedish literature policy 2012-2013 in order to make explicit the implicit assumptions embedded in the politics of readinğ This is achieved through a discourse analysis of the Swedish Government Commission report on Literature from 2012 and the subsequent Government Bill from 2013. The analysis focuses on the construction of the 'problem' that reading is supposed to solve, the subject-position of the reader, and the knowledge practices that underpin the construction of the 'problem'. The analysis reveals that the main 'problem' is the changing reading habits of the Swedish population and the decline in the reading ability of Swedish children and youth. This is seen as a threat to several important societal values, such as children's learning and development, democracy, “the culture of reading”, Sweden's economic competitiveness, and the market for literature. Responsibility for the problem is placed on the school system, parents, and the use of computers and the Internet. The remedy is seen as the promotion of the right kind of literature. Furthermore, the analysis illustrates how the subject position of the appropriate reader is formed around the notion of the harmful non-reader. Similar dividing practices are constructed around youth/adult, pupil/teacher, child/parent, and son/father where the latter is expected to make the former a reader and thereby a desirable subject. The analysis also shows how two contradictory knowledge practices are joined together in the policy texts, where seemingly rational, objective, and empirical research is paired with humanistic Bildung values

Correlations and superfluidity of a one-dimensional Bose gas in a quasiperiodic potential

We consider the correlations and superfluid properties of a Bose gas in an external potential. Using a Bogoliubov scheme, we obtain expressions for the correlation function and the superfluid density in an arbitrary external potential. These expressions are applied to a one-dimensional system at zero temperature subject to a quasiperiodic modulation. The critical parameters for the Bose glass transition are obtained using two different criteria and the results are compared. The Lifshits glass is seen to be the limiting case for vanishing interactions.Comment: Published in PRA, typos correcte

Information Research

Introduction. This study explored how various meanings are attributed to the term facts in Swedish schools and how this may shape conditions for students' learning. The understanding of information activities as social, communicative, and discursive, which motivates the study, is informed by a sociocultural perspective of learning and information interaction. Method. The study re-analyses empirical data from four previous research projects, where material was collected through various qualitative methods, mainly interviews, observations, and document analysis. The material involved 14 classes from year 2 to year 12.Analysis. The data were analysed thematically. In the material, 565 occurrences of facts are identified and categorised. Results. The analysis generated three themes. Firstly, facts were associated with specific genres or modalities. Secondly, facts were seen as distinguishable, external, and tangible. Thirdly, facts came across as having strong connections to neutrality and they were viewed as evidence. Conclusions. The analysis showed variation in how the study participants talked about facts. Despite the dominant associations, each theme displayed more complex meanings of the term, which indicates that fact cannot be equated to how the term has been used as an analytical term in previous research. The frequent use of the term facts can be understood as a result of the strong focus on students seeking and using certain types of information for writing school reports. The results show how important it is that information researchers adopt an open and explorative approach to the meaning of the language used in school activities that they study

Ansatz from Non-Linear Optics Applied to Trapped Bose-Einstein Condensates

A simple analytical ansatz, which has been used to describe the intensity profile of the similariton laser (a laser with self-similar propagation of ultrashort pulses), is used as a variational wave function to solve the Gross-Pitaevskii equation for a wide range of interaction parameters. The variational form interpolates between the noninteracting density profile and the strongly interacting Thomas-Fermi profile smoothly. The simple form of the ansatz is modified for both cylindrically symmetric and completely anisotropic harmonic traps. The resulting ground-state density profile and energy are in very good agreement with both the analytical solutions in the limiting cases of interaction and the numerical solutions in the intermediate regime.Comment: 4 pages, 3 figures, published versio

Superfluid-Insulator transition of ultracold atoms in an optical lattice in the presence of a synthetic magnetic field

We study the Mott insulator-superfluid transition of ultracold bosonic atoms in a two-dimensional square optical lattice in the presence of a synthetic magnetic field with p/q (p and q being co-prime integers) flux quanta passing through each lattice plaquette. We show that on approach to the transition from the Mott side, the momentum distribution of the bosons exhibits q precursor peaks within the first magnetic Brillouin zone. We also provide an effective theory for the transition and show that it involves q interacting boson fields. We construct, from a mean-field analysis of this effective theory, the superfluid ground states near the transition and compute, for q=2,3, both the gapped and the gapless collective modes of these states. We suggest experiments to test our theory.Comment: 4 pages, 4 figs; v

Relating two standard notions of secrecy

Two styles of definitions are usually considered to express that a security protocol preserves the confidentiality of a data s. Reachability-based secrecy means that s should never be disclosed while equivalence-based secrecy states that two executions of a protocol with distinct instances for s should be indistinguishable to an attacker. Although the second formulation ensures a higher level of security and is closer to cryptographic notions of secrecy, decidability results and automatic tools have mainly focused on the first definition so far. This paper initiates a systematic investigation of the situations where syntactic secrecy entails strong secrecy. We show that in the passive case, reachability-based secrecy actually implies equivalence-based secrecy for digital signatures, symmetric and asymmetric encryption provided that the primitives are probabilistic. For active adversaries, we provide sufficient (and rather tight) conditions on the protocol for this implication to hold.Comment: 29 pages, published in LMC

Vortices in Bose-Einstein-Condensed Atomic Clouds

The properties of vortex states in a Bose-Einstein condensed cloud of atoms are considered at zero temperature. Using both analytical and numerical methods we solve the time-dependent Gross-Pitaevskii equation for the case when a cloud of atoms containing a vortex is released from a trap. In two dimensions we find the simple result that the time dependence of the cloud radius is given by $(1+\omega^2t^2)^{1/2}$, where $\omega$ is the trap frequency. We calculate and compare the expansion of the vortex core and the cloud radius for different numbers of particles and interaction strengths, in both two and three dimensions, and discuss the circumstances under which vortex states may be observed experimentally.Comment: Revtex, 11 pages including 5 eps figures, submitted to Phys. Rev. A; new reference added, remark added in Sec. IIIB, axis label added in Fig.

Betatron emission as a diagnostic for injection and acceleration mechanisms in laser-plasma accelerators

Betatron x-ray emission in laser-plasma accelerators is a promising compact source that may be an alternative to conventional x-ray sources, based on large scale machines. In addition to its potential as a source, precise measurements of betatron emission can reveal crucial information about relativistic laser-plasma interaction. We show that the emission length and the position of the x-ray emission can be obtained by placing an aperture mask close to the source, and by measuring the beam profile of the betatron x-ray radiation far from the aperture mask. The position of the x-ray emission gives information on plasma wave breaking and hence on the laser non-linear propagation. Moreover, the measurement of the longitudinal extension helps one to determine whether the acceleration is limited by pump depletion or dephasing effects. In the case of multiple injections, it is used to retrieve unambiguously the position in the plasma of each injection. This technique is also used to study how, in a capillary discharge, the variations of the delay between the discharge and the laser pulse affect the interaction. The study reveals that, for a delay appropriate for laser guiding, the x-ray emission only occurs in the second half of the capillary: no electrons are injected and accelerated in the first half.Comment: 8 pages, 6 figures. arXiv admin note: text overlap with arXiv:1104.245

Phase diagram of quantized vortices in a trapped Bose-Einstein condensed gas

We investigate the thermodynamic stability of quantized vortices in a dilute Bose gas confined by a rotating harmonic trap at finite temperature. Interatomic forces play a crucial role in characterizing the resulting phase diagram, especially in the large $N$ Thomas-Fermi regime. We show that the critical temperature for the creation of stable vortices exhibits a maximum as a function of the frequency of the rotating trap and that the corresponding transition is associated with a discontinuity in the number of atoms in the condensate. Possible strategies for approaching the vortical region are discussed.Comment: Revtex, 4 pages, 2 figure