Full regularity for a C*-algebra of the Canonical Commutation Relations. (Erratum added)

The Weyl algebra,- the usual C*-algebra employed to model the canonical commutation relations (CCRs), has a well-known defect in that it has a large number of representations which are not regular and these cannot model physical fields. Here, we construct explicitly a C*-algebra which can reproduce the CCRs of a countably dimensional symplectic space (S,B) and such that its representation set is exactly the full set of regular representations of the CCRs. This construction uses Blackadar's version of infinite tensor products of nonunital C*-algebras, and it produces a "host algebra" (i.e. a generalised group algebra, explained below) for the \sigma-representation theory of the abelian group S where \sigma(.,.):=e^{iB(.,.)/2}. As an easy application, it then follows that for every regular representation of the Weyl algebra of (S,B) on a separable Hilbert space, there is a direct integral decomposition of it into irreducible regular representations (a known result). An Erratum for this paper is added at the end.Comment: An erratum was added to the original pape

Gravitational Lensing by Dark Matter Caustics

Dark matter caustics have specific density profiles and, therefore, precisely calculable gravitational lensing properties. We present a formalism which simplifies the relevant calculations, and apply it to four specific cases. In the first three, the line of sight is tangent to a smooth caustic surface. The curvature of the surface at the tangent point is positive, negative or zero. In the fourth case the line of sight passes near a cusp. For each we derive the map between the image and source planes. In some cases, a point source has multiple images and experiences infinite magnification when the images merge. Unfortunately, for the dark matter caustics expected in realistic galactic halo models, the angular resolution required to resolve the multiple images is not presently achievable. A more promising approach aims to observe the distortions caused by dark matter caustics in the images of extended sources such as radio jets.Comment: 36 pages, 11 figure

Alcohol-induced retrograde facilitation renders witnesses of crime less suggestible to misinformation

RATIONALE: Research has shown that alcohol can have both detrimental and facilitating effects on memory: intoxication can lead to poor memory for information encoded after alcohol consumption (anterograde amnesia) and may improve memory for information encoded before consumption (retrograde facilitation). This study examined whether alcohol consumed after witnessing a crime can render individuals less vulnerable to misleading post-event information (misinformation). METHOD: Participants watched a simulated crime video. Thereafter, one third of participants expected and received alcohol (alcohol group), one third did not expect but received alcohol (reverse placebo), and one third did not expect nor receive alcohol (control). After alcohol consumption, participants were exposed to misinformation embedded in a written narrative about the crime. The following day, participants completed a cued-recall questionnaire about the event. RESULTS: Control participants were more likely to report misinformation compared to the alcohol and reverse placebo group. CONCLUSION: The findings suggest that we may oversimplify the effect alcohol has on suggestibility and that sometimes alcohol can have beneficial effects on eyewitness memory by protecting against misleading post-event information

WIMP Annual Modulation with Opposite Phase in Late-Infall Halo Models

We show that in the late-infall model of our galactic halo by P. Sikivie the expected phase of the annual modulation of a WIMP halo signal in direct detection experiments is opposite to the one usually expected. If a non-virialized halo component due to the infall of (collisionless) dark matter particles cannot be rejected, an annual modulation in a dark matter signal should be looked for by experimenters without fixing the phase a-priori. Moreover, WIMP streams coming to Earth from directions above and below the galactic plane should be expected, with a characteristic pattern of arrival directions.Comment: 15 pages, 5 figure

Evaluating policy as argument: the public debate over the first UK austerity budget

This article aims to make a methodological contribution to the ‘argumentative turn’ in policy analysis and to the understanding of the public debate on the UK Government's austerity policies. It suggests that policy arguments are practical arguments from circumstances, goals and means–goal relations to practical conclusions (proposals) that can ground decision and action. Practical proposals are evaluated in light of their potential consequences. This article proposes a deliberation scheme and a set of critical questions for the evaluation of deliberation and decision-making in conditions of incomplete knowledge (uncertainty and risk). It illustrates these questions by analysing a corpus of articles from five newspapers over the two months following the adoption of the first austerity budget in June 2010. It also suggests how analysis of ‘frames’ and ‘framing’ can be integrated with the evaluation of deliberation and decision-making

The effect of harmonized emissions on aerosol properties in global models – an AeroCom experiment

The effects of unified aerosol sources on global aerosol fields simulated by different models are examined in this paper. We compare results from two AeroCom experiments, one with different (ExpA) and one with unified emissions, injection heights, and particle sizes at the source (ExpB). Surprisingly, harmonization of aerosol sources has only a small impact on the simulated diversity for aerosol burden, and consequently optical properties, as the results are largely controlled by model-specific transport, removal, chemistry (leading to the formation of secondary aerosols) and parameterizations of aerosol microphysics (e.g. the split between deposition pathways) and to a lesser extent on the spatial and temporal distributions of the (precursor) emissions. The burdens of black carbon and especially sea salt become more coherent in ExpB only, because the large ExpA diversity for these two species was caused by few outliers. The experiment also indicated that despite prescribing emission fluxes and size distributions, ambiguities in the implementation in individual models can lead to substantial differences. These results indicate the need for a better understanding of aerosol life cycles at process level (including spatial dispersal and interaction with meteorological parameters) in order to obtain more reliable results from global aerosol simulations. This is particularly important as such model results are used to assess the consequences of specific air pollution abatement strategies

Language and learning science in South Africa

South Africa is a multilingual country with 11 official languages. However, English dominates as the language of access and power and although the Language-in- Education Policy (1997) recommends school language policies that will promote additive bilingualism and the use of learners' home languages as languages of learning and teaching, there has been little implementation of these recommendations by schools. This is despite the fact that the majority of learners do not have the necessary English language proficiency to successfully engage with the curriculum and that teachers frequently are obliged to resort to using the learners' home language to mediate understanding. This research investigates the classroom language practices of six Grade 8 science teachers, teaching science through the medium of English where they and their learners share a common home language, Xhosa. Teachers' lessons were videotaped, transcribed and analysed for the opportunities they offered learners for language development and conceptual challenge. The purpose of the research is to better understand the teachers' perceptions and problems and to be able to draw on examples of good practice, to inform teacher training and to develop a coherent bilingual approach for teaching science through the medium of English as an additional language

Lack of correlation of stem cell markers in breast cancer stem cells

BACKGROUND: Various markers are used to identify the unique sub-population of breast cancer cells with stem cell properties. Whether these markers are expressed in all breast cancers, identify the same population of cells, or equate to therapeutic response is controversial. METHODS: We investigated the expression of multiple cancer stem cell markers in human breast cancer samples and cell lines in vitro and in vivo, comparing across and within samples and relating expression with growth and therapeutic response to doxorubicin, docetaxol and radiotherapy. RESULTS: CD24, CD44, ALDH and SOX2 expression, the ability to form mammospheres and side-population cells are variably present in human cancers and cell lines. Each marker identifies a unique rather than common population of cancer cells. In vivo, cells expressing these markers are not specifically localized to the presumptive stem cell niche at the tumour/stroma interface. Repeated therapy does not consistently enrich cells expressing these markers, although ER-negative cells accumulate. CONCLUSIONS: Commonly employed methods identify different cancer cell sub-populations with no consistent therapeutic implications, rather than a single population of cells. The relationships of breast cancer stem cells to clinical parameters will require identification of specific markers or panels for the individual cancer