3,106 research outputs found
Hypervelocity heat transfer studies in simulated planetary atmospheres final report
Hypervelocity heat transfer studies in simulated planetary atmosphere
Study of equilibrium air total radiation
Equilibrium radiation in air and gas mixtures assumed to represent near planet atmosphere
Laboratory simulation of hypervelocity heat transfer problem during planetary entry
Laboratory simulation of hypervelocity heat transfer problem during planetary entr
Image of the Energy Gap Anisotropy in the Vibrational Spectum of a High Temperature Superconductor
We present a new method of determining the anisotropy of the gap function in
layered high-Tc superconductors. Careful inelastic neutron scattering
measurements at low temperature of the phonon dispersion curves in the (100)
direction in La_(1.85)Sr_(.15)CuO_4 would determine whether the gap is
predominately s-wave or d-wave. We also propose an experiment to determine the
gap at each point on a quasi-two-dimensional Fermi surface.Comment: 12 pages + 2 figures (included
Pseudogap in 1d revisited
Two decades ago, Sadovskii found an exact solution of a model describing a
pseudogap in electron energy spectrum (first introduced by Lee, Rice and
Anderson). The discovery of a pseudogap in high-Tc superconductors has revived
the interest to his exact solution. I review the model with the emphasis on
physical content, point out an error in the original Sadovskii's solution and
explain which problem he actually solved. A recent incorporation of Sadovskii's
ideas into a description of "hot spots" on the Fermi surface in cuprate
superconductors (Schmalian, Pines and Stojkovic) is briefly discussed.Comment: Final version to appear in PR
Robot rights? Towards a social-relational justification of moral consideration \ud
Should we grant rights to artificially intelligent robots? Most current and near-future robots do not meet the hard criteria set by deontological and utilitarian theory. Virtue ethics can avoid this problem with its indirect approach. However, both direct and indirect arguments for moral consideration rest on ontological features of entities, an approach which incurs several problems. In response to these difficulties, this paper taps into a different conceptual resource in order to be able to grant some degree of moral consideration to some intelligent social robots: it sketches a novel argument for moral consideration based on social relations. It is shown that to further develop this argument we need to revise our existing ontological and social-political frameworks. It is suggested that we need a social ecology, which may be developed by engaging with Western ecology and Eastern worldviews. Although this relational turn raises many difficult issues and requires more work, this paper provides a rough outline of an alternative approach to moral consideration that can assist us in shaping our relations to intelligent robots and, by extension, to all artificial and biological entities that appear to us as more than instruments for our human purpose
Perturbation study on the spin and charge susceptibilities of the two-dimensional Hubbard model
We investigate the spin and charge susceptibilities of the two-dimensional
Hubbard model based upon the perturbative calculation in the strength of
correlation . For comparable to a bare bandwidth, the charge
susceptibility decreases near the half-filling as hole-doping approaches zero.
This behavior suggesting the precursor of the Mott-Hubbard gap formation cannot
be obtained without the vertex corrections beyond the random phase
approximation. In the low-temperature region, the spin susceptibility deviates
from the Curie-Weiss-like law and finally turns to decrease with the decrease
of temperature. This spin-gap-like behavior is originating from the van Hove
singularity in the density of states.Comment: Revtex file + 11 figures, to appear in Phys. Rev.
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