12,059 research outputs found

    The Galam Model of Minority Opinion Spreading and the Marriage Gap

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    In 2002, Serge Galam designed a model of a minority opinion spreading. The effect is expected to lead a conservative minority to prevail if the issue is discussed long enough. Here we analyze the marriage gap, i.e. the difference in voting for Bush and Kerry in 2004 between married and unmarried people. It seems possible to interpret this marriage gap in terms of the Galam model.Comment: 6 page

    Enhanced radiative strength in the quasi-continuum of 117Sn

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    Radiative strength functions of 117Sn has been measured below the neutron separation energy using the (3He,3He'gamma) reactions. An increase in the slope of the strength functions around E_gamma= 4.5 MeV indicates the onset of a resonance-like structure, giving a significant enhancement of the radiative strength function compared to standard models in the energy region 4.5 <= E_gamma <= 8.0 MeV. For the first time, the functional form of this resonance-like structure has been measured in an odd tin nucleus below neutron threshold in the quasi-continuum region.Comment: 4 pages, 3 figure

    Evidence for the pair-breaking process in 116,117Sn

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    The nuclear level densities of 116,117Sn below the neutron separation energy have been determined experimentally from the (3He,alpha gamma) and (3He,3He gamma') reactions, respectively. The level densities show a characteristic exponential increase and a difference in magnitude due to the odd-even effect of the nuclear systems. In addition, the level densities display pronounced step-like structures that are interpreted as signatures of subsequent breaking of nucleon pairs.Comment: 7 pages, 5 figures, accepted for publication in Phys. Rev. C, 22 December 200

    Strategy bifurcation and spatial inhomogeneity in a simple model of competing sellers

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    We present a simple one-parameter model for spatially localised evolving agents competing for spatially localised resources. The model considers selling agents able to evolve their pricing strategy in competition for a fixed market. Despite its simplicity, the model displays extraordinarily rich behavior. In addition to ``cheap'' sellers pricing to cover their costs, ``expensive'' sellers spontaneously appear to exploit short-term favorable situations. These expensive sellers ``speciate'' into discrete price bands. As well as variety in pricing strategy, the ``cheap'' sellers evolve a strongly correlated spatial structure, which in turn creates niches for their expensive competitors. Thus an entire ecosystem of coexisting, discrete, symmetry-breaking strategies arises.Comment: 6 pages, 6 figures, epl2; 1 new figure, include nash equilibrium analysis, typo fixe

    First-order Raman spectra of double perovskites ABâ€Č1/2B'{1/2}B''{1/2}O3

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    First principles computations of Raman intensities were performed for perovskite-family compound CaAl1/2_{1/2}Nb1/2_{1/2}O3_3 (CAN). This compound features 1:1 (NaCl-type) ordering of Al and Nb superimposed onto the b−b−c+b^-b^-c+ octahedral tilting. Raman tensor for CAN was computed using the package for first-principles computations ABINIT (URL \underline {http://www.abinit.org}). Computations performed for both untilted cubic (Fm3ˉmFm\bar{3}m) and tilted monoclinic (P21/nP2_1/n) CAN structures showed that the strongest Raman lines are associated with the ordering of Al and Nb. The computed spectrum agreed qualitatively with the experimental data measured on powder (CAN is available in polycrystalline form only). The effect of cation disorder on the Raman intensities was considered using phenomenological theory of light scattering in the vicinity of a phase transition. We suggest that, for certain modes, the corresponding Raman intensities depend primarily on the average long range order while, for other modes, the intensities are determined by fluctuations of the order parameter.Comment: 4 figures, submitte

    Longitudinal magnetic excitations in classical spin systems

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    Using spin dynamics simulations we predict the splitting of the longitudinal spin wave peak in all antiferromagnets with single site anisotropy into two peaks separated by twice the energy gap at the Brillouin zone center. This phenomenon has yet to be observed experimentally but can be easily investigated through neutron scattering experiments on MnF2_2 and FeF2_2. We have also determined that for all classical Heisenberg models the longitudinal propagative excitations are entirely multiple spin-wave in nature.Comment: four pages three figures, the last two postscript files are two parts of the third figur

    Does environmental enrichment promote recovery from stress in rainbow trout?

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    The EC Directive on animal experimentation suggests that animals should have enrichment to improve welfare yet relatively little research has been conducted on the impact of enrichment in fish. Studies on zebrafish have been contradictory and other fish species may require species specific enrichments. Salmonids are important experimental models given their relevance to aquaculture and natural ecosystems. This study sought to establish how an enriched environment may promote better welfare in rainbow trout (Oncorhynchus mykiss) enhancing their recovery from invasive procedures. Trout were held individually in either barren or enriched (gravel, plants and an area of cover) conditions and recovery rates after a potentially painful event and a standard stressor were investigated by recording parameters such as behaviour, opercular beat rate and plasma cortisol concentrations. Fish were randomly assigned to one of four treatment groups: Control where the fish were left undisturbed; Sham where fish were anaesthetised but no invasive procedure; Pain where a subcutaneous injection of acetic acid was administered to the frontal lips during anaesthesia; and Stress where fish were subject to one minute of air emersion. Video recordings were made prior to treatment then at 30 minute intervals afterwards to determine whether fish in enriched conditions recovered more rapidly than those in barren tanks. Preliminary analyses suggest that enriched fish may be less stressed thus these findings have important implications for the husbandry and welfare of captive rainbow trout but may also affect the outcome of experimental studies dependent upon whether enrichment was adopted

    The role of primary care in cancer diagnosis via emergency presentation: qualitative synthesis of significant event reports

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    Background: Patients diagnosed with cancer in the context of an emergency presentation (EP) have poorer outcomes. It is often assumed that such patients present to the emergency department without consulting their general practitioner (GP). Little work has been done to identify primary care involvement before hospital attendance. Methods: Participating primary care practices completed a significant event audit (SEA) report for the last patient diagnosed with cancer as a result of an EP. Accounts were synthesised and a qualitative approach to analysis undertaken. Results: SEAs for 222 patients were analysed. A range of cancers were included, the most common being lung (32.4%) and upper gastrointestinal (19.8%). In most cases, patients had contact with their practice before diagnosis, primarily in the period immediately before admission. In only eight cases had there been no input from primary care. Accounts of protracted primary care contact generally demonstrated complexity, often related to comorbidity, patient-mediated factors or reassurance provided by negative investigations. Learning points identified by practices centred on the themes of presentation and diagnosis, consultation and safety-netting, communication and system issues, patient factors and referral guidelines. Conclusions: There is extensive primary care input into patients whose diagnosis results from EP, and for the most part potential ‘delay’ in referral can be reasonably explained by the complexity of the presentation or by coexisting patient factors

    Level densities and Îł\gamma-ray strength functions in 170,171,172^{170,171,172}Yb

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    Level densities and radiative strength functions in 171^{171}Yb and 170^{170}Yb nuclei have been measured using the 171^{171}Yb(3^3He,3^3Heâ€ČÎł^\prime\gamma)171^{171}Yb and 171^{171}Yb(3^3He,αγ\alpha\gamma)170^{170}Yb reactions. New data on 171^{171}Yb are compared to a previous measurement for 171^{171}Yb from the 172^{172}Yb(3^3He,αγ\alpha\gamma)171^{171}Yb reaction. Systematics of level densities and radiative strength functions in 170,171,172^{170,171,172}Yb are established. The entropy excess in 171^{171}Yb relative to the even-even nuclei 170,172^{170,172}Yb due to the unpaired neutron quasiparticle is found to be approximately 2kBk_B. Results for the radiative strength function from the two reactions lead to consistent parameters characterizing the ``pygmy'' resonances. Pygmy resonances in the 170,172^{170,172}Yb populated by the (3^3He,α\alpha) reaction appear to be split into two components for both of which a complete set of resonance parameters are obtained.Comment: 8 pages, 7 figure
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