A Matrix Model for Type 0 Strings

A matrix model for type 0 strings is proposed. It consists in making a non-supersymmetric orbifold projection in the Yang-Mills theory and identifying the infrared configurations of the system at infinite coupling with strings. The correct partition function is calculated. Also, the usual spectrum of branes is found. Both type A and B models are constructed. The model in a torus contains all the degrees of freedom and interpolates between the four string theories (IIA, IIB, 0A, 0B) and the M theory as different limits are taken.Comment: 13 pages, one figure. Also available at http://condmat1.ciencias.uniovi.es

The role of high-performance people management practices in Industry 4.0: The case of medium-sized Spanish firms

Purpose: This paper wants to build the case for the key role of high-performance people management practices in the development of I4.0 in SMEs. The research upon which this paper is based wants to prove that the consolidation of those practices should be a priority for any company willing to embark in this journey. The paper deals specifically with medium-sized Spanish firms which, on top, are already having significant issues with digitization. Design/methodology: The paper starts by digging into the literature to see how past technologies have impacted productivity, followed by a review of the material available on digitization and Industry 4.0. It moves on to explore the relationship between people management practices, productivity and innovation. Finally, the focus is placed on Spanish medium-sized companies, understanding their current levels of consolidation of high-performance people management practices as well as digitization. With all this information, several propositions are posited for validation using the Delphi methodology. Findings: I4.0 is, at its core, about productivity improvements through business process and business model innovation. People management practices are found to be strongly correlated with both productivity and innovation. It has also been found that Spanish medium-sized firms already have a significant initial gap compared to those of other OECD countries not only in productivity, but also people management practices and digitization. The experts seem to agree on the key role of people management practices and that they should be a high priority for any firm seriously thinking about industry 4.0. This is not to say that strategy or leadership will not play a paramount role in any digital transformation, but to emphasize the fact that the normally-forgotten people management practices will be important enablers in this process. Originality/value: It is believed that this is a topic that has been mostly neglected in the I4.0 literature. In that sense, the findings of this paper could be relevant for small and medium-sized businesses embarking on the industry 4.0 journey. This will entail a significant investment of time and money and, if the key role of people management practices is not on the radar screen, it may have significant implications for the success of those ventures.Peer ReviewedPostprint (published version

Interfaces tecnológicos corporales en la práctica artística de María Castellanos

Este artículo se centrará en tres proyectos realizados por la artista María Castellanos (Gijón 1985) en colaboración con el matemático Alberto Valverde. De esta obra, que trata la figura del cíborg, se describen los materiales y procedimientos usados. De ellos, se destacan las herramientas de fabricación digital, como las interfaces tecnológicas corporales y la impresión 3D.This paper will focus on three projects made by the artist María Castellanos (Gijón, 1985) in collaboration with the mathematician Alberto Valverde. From this artwork, which deals with the figure of the cyborg, we describe the used materials and procedures. From these, they are highlighted digital fabrication tools such as the corporal technological interfaces and the 3D printin

The role of high-performance people management practices in Industry 4.0: the case of medium-sized Spanish firms

Purpose: This paper wants to build the case for the key role of high-performance people management practices in the development of I4.0 in SMEs. The research upon which this paper is based wants to prove that the consolidation of those practices should be a priority for any company willing to embark in this journey. The paper deals specifically with medium-sized Spanish firms which, on top, are already having significant issues with digitization. Design/methodology/approach: The paper starts by digging into the literature to see how past technologies have impacted productivity, followed by a review of the material available on digitization and Industry 4.0. It moves on to explore the relationship between people management practices, productivity and innovation. Finally, the focus is placed on Spanish medium-sized companies, understanding their current levels of consolidation of high-performance people management practices as well as digitization. With all this information, several propositions are posited for validation using the Delphi methodology. Findings: I4.0 is, at its core, about productivity improvements through business process and business model innovation. People management practices are found to be strongly correlated with both productivity and innovation. It has also been found that Spanish medium-sized firms already have a significant initial gap compared to those of other OECD countries not only in productivity, but also people management practices and digitization. The experts seem to agree on the key role of people management practices and that they should be a high priority for any firm seriously thinking about industry 4.0. This is not to say that strategy or leadership will not play a paramount role in any digital transformation, but to emphasize the fact that the normally-forgotten people management practices will be important enablers in this process. Originality/value: It is believed that this is a topic that has been mostly neglected in the I4.0 literature. In that sense, the findings of this paper could be relevant for small and medium-sized businesses embarking on the industry 4.0 journey. This will entail a significant investment of time and money and, if the key role of people management practices is not on the radar screen, it may have significant implications for the success of those ventures.Peer Reviewe

Specializations and a local homeomorphism theorem for real Riemann surfaces of rings

Let phi : k --> A and f : A --> R be ring morphisms, R a real ring. We prove that if f : A --> R is etale, then the corresponding mapping between real Riemann surfaces S-r(f) : S-r(R/k) --> S-r(A/k) is a local homeomorphism. Several preparatory results are proved, as well. The most relevant among these are: (1) a Chevalley's theorem for real Riemann surfaces on the preservation of constructibility via S-r(f), and (2) an analysis of the closure operator on real Riemann surfaces. Constructible sets are dealt with by means of a suitable first-order language

Tropical linear maps on the plane

In this paper we fully describe all tropical linear maps in the tropical projective plane, that is, maps from the tropical plane to itself given by tropical multiplication by a real 3×3 matrix A. The map fA is continuous and piecewise-linear in the classical sense. In some particular cases, the map fA is a parallel projection onto the set spanned by the columns of A. In the general case, after a change of coordinates, the map collapses at most three regions of the plane onto certain segments, called antennas, and is a parallel projection elsewhere (Theorem 3). In order to study fA, we may assume that A is normal, i.e., I A 0, up to changes of coordinates. A given matrix A admits infinitely many normalizations. Our approach is to define and compute a unique normalization for A (which we call lower canonical normalization) (Theorem 1) and then always work with it, due both to its algebraic simplicity and its geometrical meaning. On , any , some aspects of tropical linear maps have been studied in [6]. We work in , adding a geometric view and doing everything explicitly. We give precise pictures. Inspiration for this paper comes from [3,5,6,8,12,26]. We have tried to make it self-contained. Our preparatory results present noticeable relationships between the algebraic properties of a given matrix A (idempotent normal matrix, permutation matrix, etc.) and classical geometric properties of the points spanned by the columns of A (classical convexity and others); see Theorem 2 and Corollary 1. As a by-product, we compute all the tropical square roots of normal matrices of a certain type; see Corollary 4. This is, perhaps, a curious result in tropical algebra. Our final aim is, however, to give a precise description of the map . This is particularly easy when two tropical triangles arising from A (denoted and ) fit as much as possible. Then the action of fA is easily described on (the closure of) each cell of the cell decomposition ; see Theorem 3. Normal matrices play a crucial role in this paper. The tropical powers of normal matrices of size satisfy A n-1=A n=A n+1= . This statement can be traced back, at least, to [26], and appears later many times, such as [1,2,6,9,10]. In lemma 1, we give a direct proof of this fact, for n=3. But now the equality A 2=A 3 means that the columns of A 2 are three fixed points of fA and, in fact, any point spanned by the columns of A 2 is fixed by fA. Among 3×3 normal matrices, the idempotent ones (i.e., those satisfyingA=A 2) are particularly nice: we prove that the columns of such a matrix tropically span a set which is classically compact, connected and convex (Lemma 2 and Corollary 1). In our terminology, it is a good tropical triangl