7,524 research outputs found

    What has Necessity to do with Analyticity?

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    First Causes: Divine and Human

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    The paper analyzes the concept of a first cause, both for event causation and for agent causation. It turns out that one is rather ready to believe in the existence of first causes that are events, but not in the existence of first causes that are agents. The paper, however, develops and defends a complex argument to the conclusion that there is a first agent-cause. one version of that argument proves -- not necessarily the existence of God -- but still the existence of a godlike agent. Finally, the notion of a first agent-cause is employed for an analysis of freely willed human action

    Evidence of grain growth in the disk of the bipolar proto-planetary nebula M 1--92

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    We investigate the dust size and dust shell structure of the bipolar proto-planetary nebula M 1--92 by means of radiative transfer modeling. Our models consists of a disk and bipolar lobes that are surrounded by an AGB shell, each component having different dust characteristics. The upper limit of the grain size amaxa_\mathrm{max} in the lobes is estimated to be 0.5μ0.5 \mum from the polarization value in the bipolar lobe. The amaxa_\mathrm{max} value of the disk is constrained with the disk mass (0.2 M_{\sun}), which was estimated from a previous CO emission line observation. We find a good model with amax=1000.0μa_\mathrm{max}=1000.0 \mum, which provides an approximated disk mass of 0.15 M_{\sun}. Even taking into account uncertainties such as the gas-to-dust mass ratio, a significantly larger dust of amax>100.0μa_\mathrm{max}>100.0 \mum, comparing to the dust in the lobe, is expected. We also estimated the disk inner radius, the disk outer radius, and the envelope mass to be 30 RR_\star(=9 AU), 4500 AU, and 4 M_{\sun}, respectively, where vexpv_\mathrm{exp} is the expansion velocity. If the dust existing in the lobes in large separations from the central star undergoes little dust processing, the dust sizes preserves the ones in the dust formation. Submicron-sized grains are found in many objects besides M 1--92, suggesting that the size does not depend much on the object properties, such as initial mass of the central star and chemical composition of the stellar system. On the other hand, the grain sizes in the disk do. Evidence of large grains has been reported in many bipolar PPNs, including M 1--92. This result suggests that disks play an important role in grain growth.Comment: 8 pages with 3 figures. Accepted for publication in A&

    The Casimir force for passive mirrors

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    We show that the Casimir force between mirrors with arbitrary frequency dependent reflectivities obeys bounds due to causality and passivity properties. The force is always smaller than the Casimir force between two perfectly reflecting mirrors. For narrow-band mirrors in particular, the force is found to decrease with the mirrors bandwidth.Comment: 12 pages, 2 figures, LaTe

    Comparison of the π\pi and Δ\Delta operator approximations for the two-dimensional t-J model

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    We compare the spectra of the new π\pi operator of the SO(5) theory and the conventional Δ\Delta operator for the two-dimensional t-J model. We also calculate the weight transferred to the two-hole ground state from half-filling by these operators. We find that the spectra of these operators are quite similar and the weight for the π\pi operator is smaller than the weight for the Δ\Delta operator. We argue that the two-dimensional t-J model does not have a good approximate SO(5) symmetry claimed in Ref. 1.Comment: 9 latex pages, 3 figure

    Trust in ICT-Based New Product Development - Guidelines for Virtual New Product Development Teams

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    The traditional process of new product development is focusing on an intra-organizational workflow, which should - in its ideal form - be done by virtual interdisciplinary teams. Team members should be from several departments like manufacturing, research & development, sales and marketing. But innovation is happening more and more in networks of companies, clusters or so called network companies. The following article delivers a framework of guidelines for virtual team management in order to improve the success of innovation strategies.e-collaboration, virtual team work, new product development, Research and Development/Tech Change/Emerging Technologies,
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