Suborbifolds and groupoid embeddings

Given the notion of suborbifold of the second author (based on ideas of Borzellino/Brunsden) and the classical correspondence (up to certain equivalences) between (effective) orbifolds via atlases and effective orbifold groupoids, we analyze which groupoid embeddings correspond to suborbifolds and give classes of suborbifolds naturally leading to groupoid embeddings

Elliptic curves of large rank and small conductor

For r=6,7,...,11 we find an elliptic curve E/Q of rank at least r and the smallest conductor known, improving on the previous records by factors ranging from 1.0136 (for r=6) to over 100 (for r=10 and r=11). We describe our search methods, and tabulate, for each r=5,6,...,11, the five curves of lowest conductor, and (except for r=11) also the five of lowest absolute discriminant, that we found.Comment: 16 pages, including tables and one .eps figure; to appear in the Proceedings of ANTS-6 (June 2004, Burlington, VT). Revised somewhat after comments by J.Silverman on the previous draft, and again to get the correct page break

Topological insight into the non-Arrhenius mode hopping of semiconductor ring lasers

We investigate both theoretically and experimentally the stochastic switching between two counter-propagating lasing modes of a semiconductor ring laser. Experimentally, the residence time distribution cannot be described by a simple one parameter Arrhenius exponential law and reveals the presence of two different mode-hop scenarios with distinct time scales. In order to elucidate the origin of these two time scales, we propose a topological approach based on a two-dimensional dynamical system.Comment: 4 pages, 3 figure

Capas finas de ZrO2 para mejorar la resistencia química de los vidriados mates de calcio

La resistencia al ataque químico de vidriados cerámicos susceptibles al mismo, concretamente formulados a partir de una frita mate de calcio, se ha mejorado depositando en la superficie una capa delgada de óxido de circonio. Un sol de circonio estabilizado es el precursor de la capa, el cual se deposita mediante aerografía sobre el vidriado cocido y con un tratamiento térmico suave (Tmax ≈ 400 ºC), es transformado en ZrO2 y anclado a la superficie. Los ensayos de resistencia química demuestran que el vidriado protegido no sufre un ataque apreciable visualmente por parte del ácido clorhídrico concentrado, condiciones en las que el mismo vidriado sin el recubrimiento resulta gravemente dañado. El precursor utilizado genera una capa de óxido de circonio que protege el vidriado subyacente, de modo que el ataque químico por parte del ácido clorhídrico queda confinado al entorno de las grietas y discontinuidades de la capa depositadaPeer reviewe

An Analysis of Open Innovation Strategies in Firms in Low and Medium Technology Industries

Open innovation (OI) has been mainly associated with high-technology firms. This paper aims to analyze how firms in low and medium technology industries implement their OI strategy. In doing so, we explore common patterns in OI strategies by considering inbound, outbound, and coupled OI practices. We also examine whether there are differences in innovation performance among companies adopting a specific OI strategy. The study is carried out on a sample of 242 Spanish innovating companies. Based on the relevance of the different OI practices, we identify three types of OI firms: advanced open innovators, intermediate open innovators, and incipient open innovators. Our results reveal that advanced open innovators have a higher performance in product innovation, and that there are no differences among groups in process and organizational innovation

Popular Matchings in the Capacitated House Allocation Problem

We consider the problem of finding a popular matching in the Capacitated House Allocation problem (CHA). An instance of CHA involves a set of agents and a set of houses. Each agent has a preference list in which a subset of houses are ranked in strict order, and each house may be matched to a number of agents that must not exceed its capacity. A matching M is popular if there is no other matching M′ such that the number of agents who prefer their allocation in M′ to that in M exceeds the number of agents who prefer their allocation in M to that in M′. Here, we give an O(√C+n1m) algorithm to determine if an instance of CHA admits a popular matching, and if so, to find a largest such matching, where C is the total capacity of the houses, n1 is the number of agents and m is the total length of the agents’ preference lists. For the case where preference lists may contain ties, we give an O(√Cn1+m) algorithm for the analogous problem

The relationship between external knowledge absorptive capacity and firm strategy: an exploratory analysis

En este trabajo se plantea que la capacidad de absorción de la empresa variará según sea la estrategia adoptada por esta. Para ello, partiendo de que la capacidad de absorción se desarrolla a través de la habilidad para adquirir, asimilar, transformar y explotar el conocimiento generado externamente, examinamos la importancia que tiene cada una de estas dimensiones en empresas que persiguen distintas estrategias. La información ha sido obtenida de una muestra compuesta por 81 empresas españolas fabricantes de pavimentos y revestimientos cerámicos. Los resultados muestran que la capacidad de adquirir conocimiento es mayor en las empresas exploradoras que en las defensoras y en las analizadoras, y que la capacidad de transformación y la capacidad de explotación son mayores en las empresas exploradoras que en las defensoras, no observándose diferencias en la capacidad de asimilación del conocimientoIn this work we raise that a firm’s absorptive capacity differs depending on the strategy being followed by the firm. We consider that absorptive capacity is formed by the ability to acquire, assimilate, transform and exploit the knowledge generated externally and examine the importance that each one of these dimensions has in compa- nies that adopt different strategies. The information has been obtained from a sample composed by 81 Spanish ce- ramic tiles firms. The results show that the ability to acquire knowledge is higher in prospectors than in defenders and analyzers, and that the transformation and exploitation abilities are higher in the prospector firms than in the de- fenders, whereas no differences are observed in the knowledge assimilation capacit