10,537 research outputs found
Darwinism and Organizational Ecology: A Reply to Reydon and Scholz
In an earlier article published in this journal I challenge Reydon and Scholz's (2009) claim that Organizational Ecology is a non-Darwinian program. In this replay to Reydon and Scholz's subsequent response, I clarify the difference between our two approaches denoted by an emphasis her on the careful application of core Darwinian principles and an insistence by Reydon and Scholz on direct biological analogies. On a substantive issue, they identify as being the principle problem for Organizational Ecology, namely, the inability to identify replicators and interactors "of the right sort" in the business domain; this is also shown to be easily addressed with reference to empirical studies of business populations.Peer reviewedFinal Accepted Versio
Macroscopic Phase Coherence of Defective Vortex Lattices in Two Dimensions
The superfluid density is calculated theoretically for incompressible vortex
lattices in two dimensions that have isolated dislocations quenched in by a
random arrangement of pinned vortices. The latter are assumed to be sparse and
to be fixed to material defects. It is shown that the pinned vortices act to
confine a single dislocation of the vortex lattice along its glide plane.
Plastic creep of the two-dimensional vortex lattice is thereby impeded, and
macroscopic phase coherence results at low temperature in the limit of a dilute
concentration of quenched-in dislocations.Comment: 18 pages, 1 figure, 1 table, new title, submitted to Physical Review
Frame-like Geometry of Double Field Theory
We relate two formulations of the recently constructed double field theory to
a frame-like geometrical formalism developed by Siegel. A self-contained
presentation of this formalism is given, including a discussion of the
constraints and its solutions, and of the resulting Riemann tensor, Ricci
tensor and curvature scalar. This curvature scalar can be used to define an
action, and it is shown that this action is equivalent to that of double field
theory.Comment: 35 pages, v2: minor corrections, to appear in J. Phys.
Superstring partition functions in the doubled formalism
Computation of superstring partition function for the non-linear sigma model
on the product of a two-torus and its dual within the scope of the doubled
formalism is presented. We verify that it reproduces the partition functions of
the toroidally compactified type--IIA and type--IIB theories for appropriate
choices of the GSO projection.Comment: 15 page
Untangling the Conceptual Isssues Raised in Reydon and Scholz’s Critique of Organizational Ecology and Darwinian Populations
Reydon and Scholz raise doubts about the Darwinian status of organizational ecology by arguing that Darwinian principles are not applicable to organizational populations. Although their critique of organizational ecology’s typological essentialism is correct, they go on to reject the Darwinian status of organizational populations. This paper claims that the distinction between replicators and interactors, raised in modern philosophy of biology but not discussed by Reydon and Scholz, points the way forward for organizational ecologists. It is possible to conceptualise evolving Darwinian populations providing the inheritance mechanism is appropriately specified. By this approach, adaptation and selection are no longer dichotomised, and the evolutionary significance of knowledge transmission is highlightedPeer reviewe
Unmasking quality: exploring meanings of health by doing art
This paper arises from a presentation at the ‘Quality in Healthcare’ symposium at Cumberland Lodge, England, in 2013. MK, CR and SH conceived the paper and led the writing of the manuscript. JF, JL-D, AC, DE contributed substantially to the intellectual content of the paper through providing critical commentary and interpretation. All authors read and approved the final manuscript
Moody's Correlated Binomial Default Distributions for Inhomogeneous Portfolios
This paper generalizes Moody's correlated binomial default distribution for
homogeneous (exchangeable) credit portfolio, which is introduced by Witt, to
the case of inhomogeneous portfolios. As inhomogeneous portfolios, we consider
two cases. In the first case, we treat a portfolio whose assets have uniform
default correlation and non-uniform default probabilities. We obtain the
default probability distribution and study the effect of the inhomogeneity on
it. The second case corresponds to a portfolio with inhomogeneous default
correlation. Assets are categorized in several different sectors and the
inter-sector and intra-sector correlations are not the same. We construct the
joint default probabilities and obtain the default probability distribution. We
show that as the number of assets in each sector decreases, inter-sector
correlation becomes more important than intra-sector correlation. We study the
maximum values of the inter-sector default correlation. Our generalization
method can be applied to any correlated binomial default distribution model
which has explicit relations to the conditional default probabilities or
conditional default correlations, e.g. Credit Risk, implied default
distributions. We also compare some popular CDO pricing models from the
viewpoint of the range of the implied tranche correlation.Comment: 29 pages, 17 figures and 1 tabl
Heterotic-type IIA duality with fluxes
In this paper we study a possible non-perturbative dual of the heterotic
string compactified on K3 x T^2 in the presence of background fluxes. We show
that type IIA string theory compactified on manifolds with SU(3) structure can
account for a subset of the possible heterotic fluxes. This extends our
previous analysis to a case of a non-perturbative duality with fluxes.Comment: 26 pages, minor corrections; version to appear in JHE
Relaxation of strained silicon on Si0.5Ge0.5 virtual substrates
Strain relaxation has been studied in tensile strained silicon layers grown on Si0.5Ge0.5 virtual substrates, for layers many times the critical thickness, using high resolution x-ray diffraction. Layers up to 30 nm thick were found to relax less than 2% by the glide of preexisting 60° dislocations. Relaxation is limited because many of these dislocations dissociate into extended stacking faults that impede the dislocation glide. For thicker layers, nucleated microtwins were observed, which significantly increased relaxation to 14%. All these tensile strained layers are found to be much more stable than layers with comparable compressive strain
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