507 research outputs found

    Taking the right to exit seriously

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    Both diversity and autonomy liberals agree that adults have the right to exit from voluntary associations. As children do not have this right, the paradoxical character of the upbringing of children in fundamentalist and ultra-orthodox communities is evident. Diversity liberals like Galston and Spinner-Halev seem to take an ambivalent position with regard to the right to exit, because they want to defend both the child's future right to exit, which requires particular capacities, as well as the parental right to upbringing according to their conception of the good even if this undermines the required capacities. We defend that people need to be at least autarchic, that is self-determining and morally accountable, in order to be able to exercise their right to exit. Since this right is a civic freedom right, the state has the right and duty to ensure that children will be able to develop into autarchic persons. Therefore, our claim is that school education should aim for minimal autonomy and that such education should be compulsory. We argue that this will not undermine legitimate diversity and therefore that Galston and Spinner-Halev should be able to take an unequivocal position. © 2006, SAGE Publications. All rights reserved

    Self-concept and social integration. The Dutch case as an example

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    This article evaluates the credo ‘integration while maintaining one's identity’ with the help of psychological arguments. First, it explores the requirements of being a good citizen in a liberal democracy. Following Rawls, we state that justice is the cardinal liberal virtue and that this virtue includes having the disposition to respect the rights of all citizens equally. It then investigates psychological theories about identity and the relation between culture and identity. We focus on the distinction between collectivistic cultures and an interdependent self-concept on the one hand and individualistic cultures and an independent self-concept on the other. We come to the conclusion that the development into a good citizen of a liberal democracy cannot be combined with the full preservation of an interdependent self-concept. Further, we argue that the state has the right and the duty to offer civic education to all pupils, even if this means that the development of an inter-dependent self-concept of children from particular immigrant groups will be hampered. © 2004, SAGE Publications. All rights reserved

    Keplerian discs around post-AGB stars: a common phenomenon?

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    Aims: We aim at showing that the broad-band SED characteristics of our sample of post-AGB stars are best interpreted, assuming the circumstellar dust is stored in Keplerian rotating passive discs. Methods: We present a homogeneous and systematic study of the Spectral Energy Distributions (SEDs) of a sample of 51 post-AGB objects. The selection criteria to define the whole sample were tuned to cover the broad-band characteristics of known binary post-AGB stars. The whole sample includes 20 dusty RV Tauri stars from the General Catalogue of Variable Stars (GCVS). We supplemented our own Geneva optical photometry with literature data to cover a broad range of fluxes from the UV to the far-IR. Results: All the SEDs display very similar characteristics: a large IR excess with a dust excess starting near the sublimation temperature, irrespective of the effective temperature of the central star. Moreover, when available, the long wavelength fluxes show a black-body slope indicative of the presence of a component of large mm sized grains. Conclusions: We argue that in all systems, gravitationally bound dusty discs are present. The discs must be puffed-up to cover a large opening angle for the central star and we argue that the discs have some similarity with the passive discs detected around young stellar objects. We interpret the presence of a disc to be a signature for binarity of the central object, but this will need confirmation by long-term monitoring of the radial velocities. We argue that dusty RV Tauri stars are those binaries which happen to be in the Population II instability strip.Comment: 29 pages, 5 figures, accepted for publication in A&

    A Hierarchical Model of Virtual Experience and Its Influences on the Perceived Value and Loyalty of Customers

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    Many businesses use virtual experience (VE) to enhance the overall customer experience, though extant research offers little guidance for how to improve consumers’ VE. This study, anchored in activity theory, examines key drivers of VE and its influences on value perceptions and customer loyalty. A hierarchical model indicates that VE comprises second-order variables (i.e., social presence, social capital, flow experience, and situational involvement) and third-order variables (i.e., communal and individual experience). The results obtained from a substantive model further reveal that VE positively influences perceptions of both economic and social value and thus influences loyalty in both the real world and virtual environments

    Entropy and information in neural spike trains: Progress on the sampling problem

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    The major problem in information theoretic analysis of neural responses and other biological data is the reliable estimation of entropy--like quantities from small samples. We apply a recently introduced Bayesian entropy estimator to synthetic data inspired by experiments, and to real experimental spike trains. The estimator performs admirably even very deep in the undersampled regime, where other techniques fail. This opens new possibilities for the information theoretic analysis of experiments, and may be of general interest as an example of learning from limited data.Comment: 7 pages, 4 figures; referee suggested changes, accepted versio

    Universal Statistical Behavior of Neural Spike Trains

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    We construct a model that predicts the statistical properties of spike trains generated by a sensory neuron. The model describes the combined effects of the neuron's intrinsic properties, the noise in the surrounding, and the external driving stimulus. We show that the spike trains exhibit universal statistical behavior over short times, modulated by a strongly stimulus-dependent behavior over long times. These predictions are confirmed in experiments on H1, a motion-sensitive neuron in the fly visual system.Comment: 7 pages, 4 figure

    Fly Photoreceptors Demonstrate Energy-Information Trade-Offs in Neural Coding

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    Trade-offs between energy consumption and neuronal performance must shape the design and evolution of nervous systems, but we lack empirical data showing how neuronal energy costs vary according to performance. Using intracellular recordings from the intact retinas of four flies, Drosophila melanogaster, D. virilis, Calliphora vicina, and Sarcophaga carnaria, we measured the rates at which homologous R1–6 photoreceptors of these species transmit information from the same stimuli and estimated the energy they consumed. In all species, both information rate and energy consumption increase with light intensity. Energy consumption rises from a baseline, the energy required to maintain the dark resting potential. This substantial fixed cost, ∼20% of a photoreceptor's maximum consumption, causes the unit cost of information (ATP molecules hydrolysed per bit) to fall as information rate increases. The highest information rates, achieved at bright daylight levels, differed according to species, from ∼200 bits s(−1) in D. melanogaster to ∼1,000 bits s(−1) in S. carnaria. Comparing species, the fixed cost, the total cost of signalling, and the unit cost (cost per bit) all increase with a photoreceptor's highest information rate to make information more expensive in higher performance cells. This law of diminishing returns promotes the evolution of economical structures by severely penalising overcapacity. Similar relationships could influence the function and design of many neurons because they are subject to similar biophysical constraints on information throughput

    On the Role of ExperienceLab in Professional Domain Ambient Intelligence Research

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    Concept development for professional domain AmI solutions involves different stakeholders than those for consumer products, and puts different requirements on experience test methods and facilities. Philips ExperienceLab facility for experience research is described, as well as trends and lessons learned from its use in the two domains

    A silicate disk in the heart of the Ant

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    We aim at getting high spatial resolution information on the dusty core of bipolar planetary nebulae to directly constrain the shaping process. Methods: We present observations of the dusty core of the extreme bipolar planetary nebula Menzel 3 (Mz 3, Hen 2-154, the Ant) taken with the mid-infrared interferometer MIDI/VLTI and the adaptive optics NACO/VLT. The core of Mz 3 is clearly resolved with MIDI in the interferometric mode, whereas it is unresolved from the Ks to the N bands with single dish 8.2 m observations on a scale ranging from 60 to 250 mas. A striking dependence of the dust core size with the PA angle of the baselines is observed, that is highly suggestive of an edge-on disk whose major axis is perpendicular to the axis of the bipolar lobes. The MIDI spectrum and the visibilities of Mz 3 exhibit a clear signature of amorphous silicate, in contrast to the signatures of crystalline silicates detected in binary post-AGB systems, suggesting that the disk might be relatively young. We used radiative-transfer Monte Carlo simulations of a passive disk to constrain its geometrical and physical parameters. Its inclination (74 degrees ±\pm 3 degrees) and position angle (5 degrees ±\pm 5 degrees) are in accordance with the values derived from the study of the lobes. The inner radius is 9±\pm 1 AU and the disk is relatively flat. The dust mass stored in the disk, estimated as 1 x 10-5Msun, represents only a small fraction of the dust mass found in the lobes and might be a kind of relic of an essentially polar ejection process
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