7,524 research outputs found
First Causes: Divine and Human
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
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 in the lobes is estimated to be m from
the polarization value in the bipolar lobe. The 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
m, 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 m, 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 (=9 AU), 4500 AU, and 4 M_{\sun},
respectively, where 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
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 and operator approximations for the two-dimensional t-J model
We compare the spectra of the new operator of the SO(5) theory and the
conventional 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 operator is smaller than the weight for
the 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
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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