1,783 research outputs found

    Plural Rationality and Interactive Decision Processes; Proceedings of an IIASA Summer Study on Plural Rationality and Interactive Decision Processes, Sopron, Hungary, August 16-26, 1984

    Get PDF
    These Proceedings report the scientific results of the Summer Study on Plural Rationality and Interactive Decision Processes organized jointly by IIASA and the Hungarian Committee for Applied Systems Analysis. Sixty-eight researchers from sixteen countries participated, most of them contributing papers or experiments. The Study gathered specialists from many disciplines, from philosophy and cultural anthropology, through decision theory, game theory and economics, to engineering and applied mathematics. Twenty-eight of the papers presented during the Study are included in this volume

    Results from the adaptive optics coronagraph at the William Herschel Telescope

    Get PDF
    Described here is the design and commissioning of a coronagraph facility for the 4.2-m William Herschel Telescope (WHT) and its Nasmyth Adaptive Optics for Multi-purpose Instrumentation (NAOMI). The use of the NAOMI system gives an improved image resolution of 0.15 arcsec at a wavelength of 2.2 ÎŒm. This enables the Optimised Stellar Coronagraph for Adaptive optics (OSCA) to suppress stellar light using smaller occulting masks and thus allows regions closer to bright astronomical objects to be imaged. OSCA provides a selection of 10 different occulting masks with sizes of 0.25–2.0 arcsec in diameter, including two with full grey-scale Gaussian profiles. There is also a choice of different sized and shaped Lyot stops (pupil plane masks). Computer simulations of the different coronagraphic options with the NAOMI segmented mirror have relevance for the next generation of highly segmented extremely large telescopes

    The value of character-based judgement in the professional domain

    Get PDF
    Dimensions of character are often overlooked in professional practice at the expense of the development of technical competence and operational efficiency. Drawing on philosophical accounts of virtue ethics and positive psychology, the present work attempts to elevate the role of ‘good’ character in the professional domain. A ‘good’ professional is ideally one that exemplifies dimensions of character informed by sound judgement. A total of 2340 professionals, from five discrete professions, were profiled based on their valuation of qualities pertaining to character and judgement. Profile differences were subsequently examined in the self-reported experience of professional purpose towards a wider societal ‘good’. Analysis of covariance, controlling for stage of career, revealed that professionals valuing character reported higher professional purpose than those overweighting the importance of judgement or valuing neither character nor judgement, F(3, 2054) = 7.92, p < .001. No differences were found between the two groups valuing character, irrespective of whether judgement was valued simultaneously. This profiling analysis of entry-level and in-service professionals, based on their holistic character composition, paves the way for fresh philosophical discussion regarding what constitutes a ‘good’ professional and the interplay between character and judgement. The empirical findings may be of substantive value in helping to recognise how the dimensions of character and judgement may impact upon practitioners’ professional purpose

    Influence of Hydrodynamic Interactions on the Adsorption Process of Large Particles

    Full text link
    We have studied the adsorption process of non-Brownian particles on a line incorporating hydrodynamic interactionsa and we have numerically analyzed their effect on typical relevant quantities. We compare our model to the ballistic deposition model (BM) and address the limitations of BM in experimental situations. The results obtained can explain some differences observed between recent experiments and BM predictions.Comment: 10 pages, LaTeX. 4 Figures upon reques

    Model of correlated sequential adsorption of colloidal particles

    Get PDF
    We present results of a new model of sequential adsorption in which the adsorbing particles are correlated with the particles attached to the substrate. The strength of the correlations is measured by a tunable parameter σ\sigma. The model interpolates between free ballistic adsorption in the limit σ→∞\sigma\to\infty and a strongly correlated phase, appearing for σ→0\sigma\to0 and characterized by the emergence of highly ordered structures. The phenomenon is manifested through the analysis of several magnitudes, as the jamming limit and the particle-particle correlation function. The effect of correlations in one dimension manifests in the increased tendency to particle chaining in the substrate. In two dimensions the correlations induce a percolation transition, in which a spanning cluster of connected particles appears at a certain critical value σc\sigma_c. Our study could be applicable to more general situations in which the coupling between correlations and disorder is relevant, as for example, in the presence of strong interparticle interactions.Comment: 6 pages, 8 EPS figures. Phys. Rev. E (in press

    Gut microbiome and brain functional connectivity in infants-a preliminary study focusing on the amygdala

    Get PDF
    Recently, there has been a surge of interest in the possibility that microbial communities inhabiting the human gut could affect cognitive development and increase risk for mental illness via the “microbiome-gut-brain axis.” Infancy likely represents a critical period for the establishment of these relationships, as it is the most dynamic stage of postnatal brain development and a key period in the maturation of the microbiome. Indeed, recent reports indicate that characteristics of the infant gut microbiome are associated with both temperament and cognitive performance. The neural circuits underlying these relationships have not yet been delineated. To address this gap, resting-state fMRI scans were acquired from 39 1-year-old human infants who had provided fecal samples for identification and relative quantification of bacterial taxa. Measures of alpha diversity were generated and tested for associations with measures of functional connectivity. Primary analyses focused on the amygdala as manipulation of the gut microbiota in animal models alters the structure and neurochemistry of this brain region. Secondary analyses explored functional connectivity of nine canonical resting-state functional networks. Alpha diversity was significantly associated with functional connectivity between the amygdala and thalamus and between the anterior cingulate cortex and anterior insula. These regions play an important role in processing/responding to threat. Alpha diversity was also associated with functional connectivity between the supplementary motor area (SMA, representing the sensorimotor network) and the inferior parietal lobule (IPL). Importantly, SMA-IPL connectivity also related to cognitive outcomes at 2 years of age, suggesting a potential pathway linking gut microbiome diversity and cognitive outcomes during infancy. These results provide exciting new insights into the gut-brain axis during early human development and should stimulate further studies into whether microbiome-associated changes in brain circuitry influence later risk for psychopathology

    Kinematical and nonlocality effects on the nonmesonic weak hypernuclear decay

    Full text link
    We derive in detail the transition potential for nonmesonic lambda-hypernuclear decay in a one-meson-exchange model involving the full pseudoscalar and vector meson octets and including two effects that have been systematically omitted in the literature. These are the kinematical effects due to the difference between the lambda and nucleon masses and the first-order nonlocality corrections. Numerical results for Λ12^{12}_\LambdaC and Λ5^5_\LambdaHe are presented and they show that the combined kinematical plus nonlocal corrections have an appreciable influence on the partial decay rates. However, this is somewhat diminished in the main decay observables: the total nonmesonic rate, the neutron-to-proton branching ratio, and the asymmetry parameter. The latter two still cannot be reconciled with the available experimental data. The existing theoretical predictions for the sign of the asymmetry parameter in Λ5^5_\LambdaHe are confirmed.Comment: 36 pages; LaTeX2e; 1 eps figure. Changes: 2 more tables and 14 new references added; effects on asymmetry parameter calculated; discussions expanded; more definite conclusions reache

    Entropy and Spin Susceptibility of s-wave Type-II Superconductors near Hc2H_{c2}

    Get PDF
    A theoretical study is performed on the entropy SsS_{\rm s} and the spin susceptibility χs\chi_{\rm s} near the upper critical field Hc2H_{c2} of s-wave type-II superconductors with arbitrary impurity concentrations. The changes of these quantities through Hc2H_{c2} may be expressed as [Ss(T,B)−Ss(T,0)]/[Sn(T)−Ss(T,0)]=1−αS(1−B/Hc2)≈(B/Hc2)αS[S_{\rm s}(T,B)-S_{\rm s}(T,0)]/[S_{\rm n}(T)-S_{\rm s}(T,0)]=1-\alpha_{S}(1-B/H_{c2})\approx (B/H_{c2})^{\alpha_{S}}, for example, where BB is the average flux density and SnS_{\rm n} denotes entropy in the normal state. It is found that the slopes αS\alpha_{S} and αχ\alpha_{\chi} at T=0 are identical, connected directly with the zero-energy density of states, and vary from 1.72 in the dirty limit to 0.5∌0.60.5\sim 0.6 in the clean limit. This mean-free-path dependence of αS\alpha_{S} and αχ\alpha_{\chi} at T=0 is quantitatively the same as that of the slope αρ(T=0)\alpha_{\rho}(T=0) for the flux-flow resistivity studied previously. The result suggests that Ss(B)S_{\rm s}(B) and χs(B)\chi_{\rm s}(B) near T=0 are convex downward (upward) in the dirty (clean) limit, deviating substantially from the linear behavior ∝B/Hc2\propto B/H_{c2}. The specific-heat jump at Hc2H_{c2} also shows fairly large mean-free-path dependence.Comment: 8 pages, 5 figure

    Study of the radiative decay Ï•â†’Î·Îł\phi \to \eta \gamma with CMD-2 detector

    Full text link
    Using the 1.9pb−11.9 pb^{-1} of data collected with the CMD-2 detector at VEPP-2M the decay mode Ï•â†’Î·Îł\phi \to \eta \gamma, η→π+π−π0\eta \to \pi^+\pi^-\pi^0 has been studied. The obtained branching ratio is B(Ï•â†’Î·Îł)=(1.18±0.03±0.06)\phi \to \eta \gamma) = (1.18 \pm 0.03 \pm 0.06) %.Comment: 13 pages, 5 figures, LaTex2e, to be published in Phys. Lett.

    Effects of rapid prey evolution on predator-prey cycles

    Full text link
    We study the qualitative properties of population cycles in a predator-prey system where genetic variability allows contemporary rapid evolution of the prey. Previous numerical studies have found that prey evolution in response to changing predation risk can have major quantitative and qualitative effects on predator-prey cycles, including: (i) large increases in cycle period, (ii) changes in phase relations (so that predator and prey are cycling exactly out of phase, rather than the classical quarter-period phase lag), and (iii) "cryptic" cycles in which total prey density remains nearly constant while predator density and prey traits cycle. Here we focus on a chemostat model motivated by our experimental system [Fussmann et al. 2000,Yoshida et al. 2003] with algae (prey) and rotifers (predators), in which the prey exhibit rapid evolution in their level of defense against predation. We show that the effects of rapid prey evolution are robust and general, and furthermore that they occur in a specific but biologically relevant region of parameter space: when traits that greatly reduce predation risk are relatively cheap (in terms of reductions in other fitness components), when there is coexistence between the two prey types and the predator, and when the interaction between predators and undefended prey alone would produce cycles. Because defense has been shown to be inexpensive, even cost-free, in a number of systems [Andersson and Levin 1999, Gagneux et al. 2006,Yoshida et al. 2004], our discoveries may well be reproduced in other model systems, and in nature. Finally, some of our key results are extended to a general model in which functional forms for the predation rate and prey birth rate are not specified.Comment: 35 pages, 8 figure
    • 

    corecore