5,394 research outputs found
MICRO-Foundations in Strategic Management: Squaring Coleman's Diagram
Abell, Felin and Foss argue that "macro-explanations" in strategic management, explanations in which organizational routines figure prominently and in which both the explanandum and explanans are at the macro-level, are necessarily incomplete. They take a diagram (which has the form of a trapezoid) from Coleman, Foundations of Social Theory, The Belknap Press of Harvard University Press, Cambridge (Mass.)/London, (1990) to task to show that causal chains connecting two macro-phenomena always involve "macro-to-micro" and "micro-to-macro" links, links that macro-explanations allegedly fail to recognize. Their plea for micro-foundations in strategic management is meant to shed light on these "missing links". The paper argues that while there are good reasons for providing micro-foundations, Abell, Felin and Foss's causal incompleteness argument is not one of them. Their argument does not sufficiently distinguish between causal and constitutive relations. Once these relations are carefully distinguished, it follows that Coleman's diagram has to be squared. This in turn allows us to see that macro-explanations need not be incomplete
Holographic metastability
We show how supersymmetric QCD in a slice of AdS can naturally acquire
metastable vacua. The formulation closely follows that of Intriligator, Seiberg
and Shih (ISS), with an "electric" sector on the UV brane and a "magnetic"
sector on the IR brane. However the 't Hooft anomaly matching that constrains
the Seiberg duality central to ISS is replaced by anomaly inflow and
cancellation, and the source of strong coupling is the CFT to which the theory
couples rather than the gauge groups. The theory contains an anomaly free
R-symmetry that, when broken by UV effects, leads to an O'Raifeartaigh model on
the IR brane. In contrast to ISS, the R-symmetry breaking in the UV can be
maximal, and yet the R-symmetry breaking in the IR theory remains under strict
control: there is no need for retrofitting of small parameters.Comment: 20 pages, 2 figure
Bounds on 4D Conformal and Superconformal Field Theories
We derive general bounds on operator dimensions, central charges, and OPE
coefficients in 4D conformal and N=1 superconformal field theories. In any CFT
containing a scalar primary phi of dimension d we show that crossing symmetry
of implies a completely general lower bound on the central
charge c >= f_c(d). Similarly, in CFTs containing a complex scalar charged
under global symmetries, we bound a combination of symmetry current two-point
function coefficients tau^{IJ} and flavor charges. We extend these bounds to
N=1 superconformal theories by deriving the superconformal block expansions for
four-point functions of a chiral superfield Phi and its conjugate. In this case
we derive bounds on the OPE coefficients of scalar operators appearing in the
Phi x Phi* OPE, and show that there is an upper bound on the dimension of Phi*
Phi when dim(Phi) is close to 1. We also present even more stringent bounds on
c and tau^{IJ}. In supersymmetric gauge theories believed to flow to
superconformal fixed points one can use anomaly matching to explicitly check
whether these bounds are satisfied.Comment: 47 pages, 9 figures; V2: small corrections and clarification
Thermodynamics of Holographic Defects
Using the AdS/CFT correspondence, we study the thermodynamic properties and
the phase diagram of matter fields on (2+1)-dimensional defects coupled to a
(3+1)-dimensional N=4 SYM "heat bath". Considering a background magnetic field,
(net) quark density, defect "magnitude" and the mass of the
matter, we study the defect contribution to the thermodynamic potentials and
their first and second derivatives to map the phases and study their physical
properties.
We find some features that are qualitatively similar to other systems e.g. in
(3+1) dimensions and a number of features that are particular to the defect
nature, such as its magnetic properties, unexpected properties at T->0 and
finite density; and the finite effects, e.g. a diverging
susceptibility and vanishing density of states at small temperatures, a
physically consistent negative heat capacity and new types of consistent
phases.Comment: 33 pages, 16 figures (jpg and pdf), typos fixed and references added,
final version published in JHE
A slice of AdS_5 as the large N limit of Seiberg duality
A slice of AdS_5 is used to provide a 5D gravitational description of 4D
strongly-coupled Seiberg dual gauge theories. An (electric) SU(N) gauge theory
in the conformal window at large N is described by the 5D bulk, while its
weakly coupled (magnetic) dual is confined to the IR brane. This framework can
be used to construct an N = 1 MSSM on the IR brane, reminiscent of the original
Randall-Sundrum model. In addition, we use our framework to study
strongly-coupled scenarios of supersymmetry breaking mediated by gauge forces.
This leads to a unified scenario that connects the extra-ordinary gauge
mediation limit to the gaugino mediation limit in warped space.Comment: 47 Pages, axodraw4j.st
Signatures of arithmetic simplicity in metabolic network architecture
Metabolic networks perform some of the most fundamental functions in living
cells, including energy transduction and building block biosynthesis. While
these are the best characterized networks in living systems, understanding
their evolutionary history and complex wiring constitutes one of the most
fascinating open questions in biology, intimately related to the enigma of
life's origin itself. Is the evolution of metabolism subject to general
principles, beyond the unpredictable accumulation of multiple historical
accidents? Here we search for such principles by applying to an artificial
chemical universe some of the methodologies developed for the study of genome
scale models of cellular metabolism. In particular, we use metabolic flux
constraint-based models to exhaustively search for artificial chemistry
pathways that can optimally perform an array of elementary metabolic functions.
Despite the simplicity of the model employed, we find that the ensuing pathways
display a surprisingly rich set of properties, including the existence of
autocatalytic cycles and hierarchical modules, the appearance of universally
preferable metabolites and reactions, and a logarithmic trend of pathway length
as a function of input/output molecule size. Some of these properties can be
derived analytically, borrowing methods previously used in cryptography. In
addition, by mapping biochemical networks onto a simplified carbon atom
reaction backbone, we find that several of the properties predicted by the
artificial chemistry model hold for real metabolic networks. These findings
suggest that optimality principles and arithmetic simplicity might lie beneath
some aspects of biochemical complexity
Classical kinetic energy, quantum fluctuation terms and kinetic-energy functionals
We employ a recently formulated dequantization procedure to obtain an exact
expression for the kinetic energy which is applicable to all kinetic-energy
functionals. We express the kinetic energy of an N-electron system as the sum
of an N-electron classical kinetic energy and an N-electron purely quantum
kinetic energy arising from the quantum fluctuations that turn the classical
momentum into the quantum momentum. This leads to an interesting analogy with
Nelson's stochastic approach to quantum mechanics, which we use to conceptually
clarify the physical nature of part of the kinetic-energy functional in terms
of statistical fluctuations and in direct correspondence with Fisher
Information Theory. We show that the N-electron purely quantum kinetic energy
can be written as the sum of the (one-electron) Weizsacker term and an
(N-1)-electron kinetic correlation term. We further show that the Weizsacker
term results from local fluctuations while the kinetic correlation term results
from the nonlocal fluctuations. For one-electron orbitals (where kinetic
correlation is neglected) we obtain an exact (albeit impractical) expression
for the noninteracting kinetic energy as the sum of the classical kinetic
energy and the Weizsacker term. The classical kinetic energy is seen to be
explicitly dependent on the electron phase and this has implications for the
development of accurate orbital-free kinetic-energy functionals. Also, there is
a direct connection between the classical kinetic energy and the angular
momentum and, across a row of the periodic table, the classical kinetic energy
component of the noninteracting kinetic energy generally increases as Z
increases.Comment: 10 pages, 1 figure. To appear in Theor Chem Ac
Superconformal Flavor Simplified
A simple explanation of the flavor hierarchies can arise if matter fields
interact with a conformal sector and different generations have different
anomalous dimensions under the CFT. However, in the original study by Nelson
and Strassler many supersymmetric models of this type were considered to be
'incalculable' because the R-charges were not sufficiently constrained by the
superpotential. We point out that nearly all such models are calculable with
the use of a-maximization. Utilizing this, we construct the simplest
vector-like flavor models and discuss their viability. A significant constraint
on these models comes from requiring that the visible gauge couplings remain
perturbative throughout the conformal window needed to generate the
hierarchies. However, we find that there is a small class of simple flavor
models that can evade this bound.Comment: 43 pages, 1 figure; V3: small corrections and clarifications,
references adde
Criminal and Noncriminal Psychopathy: The Devil is in the Detail
Brooks, NS ORCiD: 0000-0003-1784-099XPsychopathy is prevalent and problematic in criminal populations, but is also found to be present in noncriminal populations. In 1992, Robert Hare declared that psychopaths may also “be found in the boardroom”, which has since been followed by an interest in the issue of noncriminal, or even successful, psychopathy. In this chapter, the paradox of criminal and noncriminal psychopathy is discussed with specific attention given to the similarities and differences that account for psychopathic personality across contexts. That psychopathy is a condition typified by a constellation of traits and behaviours requires wider research across diverse populations, and thus the streams of research related to criminal and noncriminal psychopathy are presented and the implications of these contrasting streams are explored
A comprehensive 1000 Genomes-based genome-wide association meta-analysis of coronary artery disease
Existing knowledge of genetic variants affecting risk of coronary artery disease (CAD) is largely based on genome-wide association studies (GWAS) analysis of common SNPs. Leveraging phased haplotypes from the 1000 Genomes Project, we report a GWAS meta-analysis of 185 thousand CAD cases and controls, interrogating 6.7 million common (MAF>0.05) as well as 2.7 million low frequency (0.005<MAF<0.05) variants. In addition to confirmation of most known CAD loci, we identified 10 novel loci, eight additive and two recessive, that contain candidate genes that newly implicate biological processes in vessel walls. We observed intra-locus allelic heterogeneity but little evidence of low frequency variants with larger effects and no evidence of synthetic association. Our analysis provides a comprehensive survey of the fine genetic architecture of CAD showing that genetic susceptibility to this common disease is largely determined by common SNPs of small effect siz
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