On permanents of Sylvester Hadamard matrices

It is well-known that the evaluation of the permanent of an arbitrary $(-1,1)$-matrix is a formidable problem. Ryser's formula is one of the fastest known general algorithms for computing permanents. In this paper, Ryser's formula has been rewritten for the special case of Sylvester Hadamard matrices by using their cocyclic construction. The rewritten formula presents an important reduction in the number of sets of $r$ distinct rows of the matrix to be considered. However, the algorithm needs a preprocessing part which remains time-consuming in general

On an inequivalence criterion for cocyclic Hadamard matrices

Given two Hadamard matrices of the same order, it can be quite difficult to decide whether or not they are equivalent. There are some criteria to determine Hadamard inequivalence. Among them, one of the most commonly used is the 4-profile criterion. In this paper, a reformulation of this criterion in the cocyclic framework is given. The improvements obtained in the computation of the 4-profile of a cocyclic Hadamard matrix are indicated.Ministerio de Ciencia e Innovación MTM2008-06578Junta de Andalucía FQM–296Junta de Andalucía P07-FQM-0298

Self-Dual codes from (−1,1)(-1,1)-matrices of skew symmetric type

Previously, self-dual codes have been constructed from weighing matrices, and in particular from conference matrices (skew and symmetric). In this paper, codes constructed from matrices of skew symmetric type whose determinants reach the Ehlich-Wojtas' bound are presented. A necessary and sufficient condition for these codes to be self-dual is given, and examples are provided for lengths up to 52

Using seam to better understand born globals. A spanish case

This work presents a systematic overview of the opportunities and challenges for international ventures. Moreover, it seeks to reflect on success-factors of launching a venture in international context and how Socio-Economic Approach to Management (SEAM) can help. Using a practical case study, we discuss the limitations of the “state of art” in BGs and reflect on what SEAM can provide in understanding the main managerial complexities faced by BGs and in leading BGs change in order that they develop the dynamic capabilities to succeed in International markets.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Internal orientation in the growth of Born-Globals. Learning from inside

Este paper ha recibido dos premios en el congreso: 1. Thomson South-Western Award OUTSTANDING RESEARCH-BASED PAPER ON MANAGEMENT CONSULTING 2. FINALIST CAROLYN DEXTER AWARD FOR BEST INTERNATIONAL PAPERBased on a longitudinal case study in a young BG by means of action-research, that allows the participation of all employees in the co-creation of internal knowledge, we identify organisational dysfunctions during the early phase that affect the development of entrepreneurial and market orientation. Using the Socio-Economic Approach to Management (Savall, 1974), we propose that the entrepreneurs need to adopt an Internal Orientation (aiming at developing a cohesive organisation), and that the ‘right time’ for doing so is not after a few years, as the literature suggests, but much earlier.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Generalized binary arrays from quasi-orthogonal cocycles

Generalized perfect binary arrays (GPBAs) were used by Jedwab to construct perfect binary arrays. A non-trivial GPBA can exist only if its energy is 2 or a multiple of 4. This paper introduces generalized optimal binary arrays (GOBAs) with even energy not divisible by 4, as analogs of GPBAs. We give a procedure to construct GOBAs based on a characterization of the arrays in terms of 2-cocycles. As a further application, we determine negaperiodic Golay pairs arising from generalized optimal binary sequences of small length.Junta de Andalucía FQM-01

On quasi-orthogonal cocycles

We introduce the notion of quasi-orthogonal cocycle. This is motivated in part by the maximal determinant problem for square {±1}-matrices of size congruent to 2 modulo 4. Quasi-orthogonal cocycles are analogous to the orthogonal cocycles of algebraic design theory. Equivalences with new and known combinatorial objects afforded by this analogy, such as quasi-Hadamard groups, relative quasi-difference sets, and certain partially balanced incomplete block designs, are proved.Junta de Andalucía FQM-01

Self-Dual codes from (−1,1)-matrices of skew symmetric type

Previously, self-dual codes have been constructed from weighing matrices, and in particular from conference matrices (skew and symmetric). In this paper, codes constructed from matrices of skew symmetric type whose determinants reach the Ehlich- Wojtas’ bound are presented. A necessary and sufficient condition for these codes to be self-dual is given, and examples are provided for lengths up to 52.Ministerio de Ciencia e Innovación MTM2008-06578Junta de Andalucía FQM-016Junta de Andalucía P07-FQM-0298

Severe Atopic Dermatitis In Spain: A Real-Life Observational Study

Objective: To determine the epidemiology and characterize the treatment prescribed for severe atopic dermatitis (AD) in children/adults in usual clinical practice. Methods: Observational, retrospective study made through review of medical records of Spanish patients aged >= 6 years. Patients diagnosed with severe AD who required care between 2013 and 2017 were included. The study groups were: 6-12 years; 13-18 years; and > 18 years. Patients were followed for 5 years. The main measurements were the prevalence of AD, comorbidity and treatment duration. Statistical significance was established as p <0.05. Results: We included 2323 patients with severe AD. The overall prevalence was 0.10% (95% CI: 0.09-0.11%) and was 0.39%, 0.23% and 0.07% in the 6-12 years, 13-18 years and >18 years age groups, respectively (p <0.001), the percentage of males was 58%, 48.6% and 39%, respectively, and general comorbidity was 0.1, 0.2 and 0.9 points, respectively (p <0.001).The most frequent comorbidities were asthma in 49.0%, 44.9% and 20.8%, respectively (p <0.001), and anxiety in 79.7%, 65.8% and 67.3%, respectively (p <0.001). Oral corticosteroids were administered in 97.3%, 90.9% and 81.7%, respectively (concomitant-medication). Cyclosporine (45.3%), azathioprine (15.9%) and methotrexate (9.0%) were the most frequently prescribed drugs; biologic agents were administered in 5.8% of patients (for AD). Conclusion: In AD the presence of comorbidities was significant, especially in the psychological, immunoallergic and cardiovascular areas. Cyclosporine was the most widely used immunosuppressant. There was a degree of variability in the use and duration of the treatments prescribed