Capabilities, Confusion, and the Costs of Coordination On Some Problems in Recent Research On Inter-Firm Relations

The arguably dominant approaches to the study of interfirm relations are the capabilities and organizational economics perspectives. This paper discusses their merits and weaknesses, concentrating on the capabilities perspective, which is argued to rest on rather weak foundations, particularly as a theory of economic organization (including interfirm relations). However, it is suggested that both perspectives may be seen as part of an overarching bargaining approach to economic organization (yet to be developed). Both perspectives have identified impediments to efficient bargaining.Interfirm relations, capabilities, organizational economics, research methodology

Universality of the Operator Product Expansions of SCFT_4

We study the operator product algebra of the supercurrent J and Konishi superfield K in four-dimensional supersymmetric gauge theories. The Konishi superfield appears in the JJ OPE and the algebra is characterized by two central charges c and c' and an anomalous dimension h for K. In free field (one-loop) approximation, c~3N_v+N_\chi and c'~N_\chi, where N_v and N_\chi are, respectively, the number of vector and chiral multiplets in the theory. In higher order c, c' and h depend on the gauge and Yukawa couplings and we obtain the two-loop contributions by combining earlier work on c with our own calculations of c'. The major result is that the radiative corrections to the central charges cancel when the one-loop beta-functions vanish, suggesting that c and c' (but not h) are invariant under continuous deformations of superconformal theories. The behavior of c and c' along renormalization group flows is studied from the viewpoint of a c-theorem.Comment: LaTeX file, 11 pages, no figur

A Lambda Term Representation Inspired by Linear Ordered Logic

We introduce a new nameless representation of lambda terms inspired by ordered logic. At a lambda abstraction, number and relative position of all occurrences of the bound variable are stored, and application carries the additional information where to cut the variable context into function and argument part. This way, complete information about free variable occurrence is available at each subterm without requiring a traversal, and environments can be kept exact such that they only assign values to variables that actually occur in the associated term. Our approach avoids space leaks in interpreters that build function closures. In this article, we prove correctness of the new representation and present an experimental evaluation of its performance in a proof checker for the Edinburgh Logical Framework. Keywords: representation of binders, explicit substitutions, ordered contexts, space leaks, Logical Framework.Comment: In Proceedings LFMTP 2011, arXiv:1110.668

Integration of statistics and food process engineering: Assessing the uncertainty of thermal processing and shelf-life estimations

Resumo indisponível

PCR-based characterisation of entomopathogenic fungi for ecological studies

The implementation of PCR-based tools for characterisation of organisms has greatly advanced our understanding of the phylogenies and species boundaries in entomopathogenic fungi, especially the widespread taxa Beauveria bassiana and Metarhizium anisopliae. These fungi have received a lot of interest due to their potential as biocontrol agents of pests. However, there is still a lack of knowledge about the fundamental ecology of these fungi in both managed and natural ecosystems, but such information is necessary both for risk assessments prior to release of biocontrol agents in the environment as well as if we wish to understand the distribution of the fungi and their impact on host populations. This latter focus is essential if the fungi are to be included in pest management strategies based on conservation biological control. A series of unspecific PCR methods have been used to characterise isolates of B. bassiana and M. anisopliae, and many studies have concluded that the fungi contain a lot of genetic diversity. The problem with these methods is that they provide little phylogenetic information of the fungi and the characters can not be used to explicitly compare data between studies. Sequences from specific targets in the DNA provide tools for explicit comparison between isolates across studies. There is now a range of primer sets published along with reference sequences in GenBank to make these comparisons possible. Multi-gene phylogenies have revealed that both B. bassiana and M. anisopliae are complexes of species that contain cryptic taxa or clades. Using merely morphological characteristics will not result in the same degree of taxa identification as will the use of DNA sequence data. Similarly, when using microsatellite markers for population genetic studies of fungal communities, it is necessary to first separate the populations in clades as allele sizes can convert across populations. In the near future, USDA-ARS in Beltsville will launch a web-based platform (MBID, Metarhizium-Beauveria ID) including lists of primers, databases of reference sequences and type isolates of new described species for the reliable identification of taxa for the scientific community. This tool should provide a common framework and nomenclature for scientists and create basis for making comparisons among studies. There should be great potential to learn more about the ecology of the entomopathogenic fungi with the application of these molecular markers. However, designing an appropriate sampling scheme in the environment is absolutely necessary to conduct these ecological studies. The use of isolates from culture collections should be avoided

Complex viscosity behavior and cluster formation in attractive colloidal systems

The increase of the viscosity, which is observed in attractive colloidal systems by varying the temperature or the volume fraction, can be related to the formation of structures due to particle aggregation. In particular we have studied the non trivial dependence of the viscosity from the temperature and the volume fraction in the copolymer-micellar system L64. The comparison of the experimental data with the results of numerical simulations in a simple model for gelation phenomena suggests that this intriguing behavior can be explained in terms of cluster formation and that this picture can be quite generally extended to other attractive colloidal systems.Comment: 5 pages, 4 figure

On Some Stability Properties of Compactified D=11 Supermembranes

We desribe the minimal configurations of the bosonic membrane potential, when the membrane wraps up in an irreducible way over $S^{1}\times S^{1}$. The membrane 2-dimensional spatial world volume is taken as a Riemann Surface of genus $g$ with an arbitrary metric over it. All the minimal solutions are obtained and described in terms of 1-forms over an associated U(1) fiber bundle, extending previous results. It is shown that there are no infinite dimensional valleys at the minima.Comment: 12 pages,Latex2e lamuphys, Invited talk at International Seminar "Supersymetry and Quantum Symmetries", Dubn

Octonionic Gravitational Instantons

We construct eight-dimensional gravitational instantons by solving appropriate self-duality equations for the spin-connection. The particular gravitational instanton we present has $Spin(7)$ holonomy and, in a sense, it is the eight-dimensional analog of the Eguchi-Hanson 4D space. It has a removable bolt singularity which is topologically S^4 and its boundary at infinity is the squashed S^7. We also lift our solutions to ten and eleven dimensions and construct fundamental string and membrane configurations that preserve 1/16 of the original supersymmetries.Comment: 17 pages, latex, no figures. References to earlier works adde