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Global Competition, Institutions, And The Diffusion Of Organizational Practices: The International Spread Of Iso 9000 Quality Certificates
We use panel data on ISO 9000 quality certification in 85 countries between 1993 and 1998 to better understand, the cross-national diffusion of an organizational practice. Following neoinstitutional theory, we focus on the coercive, normative, and mimetic effects that result from the exposure of firms in a given country to a powerful source of critical resources, a common pool of relevant technical knowledge, and the experiences of firms located in other countries. We use social network theory to develop a systematic conceptual understanding of how firms located in different countries influence each other's rates of adoption as a result of cohesive and equivalent network relationships. Regression results provide support for our predictions that states and foreign multinationals are the key actors responsible for coercive isomorphism, cohesive trade relationships between countries generate coercive and normative effects, and role-equivalent trade relationships result in learning-based and competitive imitation.Business Administratio
Origin of transition metal clustering tendencies in GaAs based dilute magnetic semiconductors
While isovalent doping of GaAs (e.g. by In) leads to a repulsion between the
solute atoms, two Cr, Mn, or Fe atoms in GaAs are found to have lower energy
than the well-separated pair, and hence attract each other. The strong bonding
interaction between levels with t2 symmetry on the transition metal (TM) atoms
results in these atoms exhibiting a strong tendency to cluster. Using
first-principles calculations, we show that this attraction is maximal for Cr,
Mn and Fe while it is minimal for V. The difference is attributed to the
symmetry of the highest occupied levels. While the intention is to find
possible choices of spintronic materials that show a reduced tendency to
cluster, one finds that the conditions that minimize clustering tendencies also
minimize the stabilization of the magnetic state.Comment: To appear in Appl. Phys. Let
Supersymmetric extensions of K field theories
We review the recently developed supersymmetric extensions of field theories
with non-standard kinetic terms (so-called K field theories) in two an three
dimensions. Further, we study the issue of topological defect formation in
these supersymmetric theories. Specifically, we find supersymmetric K field
theories which support topological kinks in 1+1 dimensions as well as
supersymmetric extensions of the baby Skyrme model for arbitrary nonnegative
potentials in 2+1 dimensions.Comment: Contribution to the Proceedings of QTS7, Prague, August 201
Extended Supersymmetry and BPS solutions in baby Skyrme models
We continue the investigation of supersymmetric extensions of baby Skyrme
models in d=2+1 dimensions. In a first step, we show that the CP(1) form of the
baby Skyrme model allows for the same N=1 SUSY extension as its O(3)
formulation. Then we construct the N=1 SUSY extension of the gauged baby Skyrme
model, i.e., the baby Skyrme model coupled to Maxwell electrodynamics. In a
next step, we investigate the issue of N=2 SUSY extensions of baby Skyrme
models. We find that all gauged and ungauged submodels of the baby Skyrme model
which support BPS soliton solutions allow for an N=2 extension such that the
BPS solutions are one-half BPS states (i.e., annihilated by one-half of the
SUSY charges). In the course of our investigation, we also derive the general
BPS equations for completely general N=2 supersymmetric field theories of (both
gauged and ungauged) chiral superfields, and apply them to the gauged nonlinear
sigma model as a further, concrete example.Comment: 32 pages, Latex fil
Thermodynamics of the BPS Skyrme model
One problem in the application of the Skyrme model to nuclear physics is that
it predicts too large a value for the compression modulus of nuclear matter.
Here we investigate the thermodynamics of the BPS Skyrme model at zero
temperature and calculate its equation of state. Among other results, we find
that classically (i.e. without taking into account quantum corrections) the
compressibility of BPS skyrmions is, in fact, infinite, corresponding to a zero
compression modulus. This suggests that the inclusion of the BPS submodel into
the Skyrme model lagrangian may significantly reduce this too large value,
providing further evidence for the claim that the BPS Skyrme model may play an
important role in the description of nuclei and nuclear matter.Comment: Latex, 26 pages, 1 figure; v2: some typos corrected, version accepted
for publication in Phys. Rev.
Symmetries and exact solutions of the BPS Skyrme model
The BPS Skyrme model is a specific subclass of Skyrme-type field theories
which possesses both a BPS bound and infinitely many soliton solutions
(skyrmions) saturating that bound, a property that makes the model a very
convenient first approximation to the study of some properties of nuclei and
hadrons. A related property, the existence of a large group of symmetry
transformations, allows for solutions of rather general shapes, among which
some of them will be relevant to the description of physical nuclei.
We study here the classical symmetries of the BPS Skyrme model, applying them
to construct soliton solutions with some prescribed shapes, what constitutes a
further important step for the reliable application of the model to strong
interaction physics.Comment: Latex, 17 page
A BPS Skyrme model
Within the set of generalized Skyrme models, we identify a submodel which has
both infinitely many symmetries and a Bogomolny bound which is saturated by
infinitely many exact soliton solutions. Concretely, the submodel consists of
the square of the baryon current and a potential term only. Further, already on
the classical level, this BPS Skyrme model reproduces some features of the
liquid drop model of nuclei. Here, we review the properties of the model and we
discuss the semiclassical quantization of the simplest Skyrmion (the nucleon).Comment: Conference Proceedings of the 28th International Colloquium On Group
Theoretical Methods In Physics (GROUP 28), July 2010, Northumbria, England.
10pages, 1 figure. Version 2: Publication information adde
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