Intended Ties with Local Institutions as a Factor in Innovation: An Application to Spanish Manufacturing Firms

In this paper we seek to check for a number of interactions between firms and external environment. We aim to contribute to the discussion on the role of the regional environment in a firm’s innovation performance. We test the statistical significance of a number of particular interactions between institutions and firm innovation. In particular, we have hypothesized the association between trade and professional institutions, technological centers, and cooperation arrangements and innovation. In contrast with existing studies, we have provided empirical evidence of the impact of external factors on individual firm

Factores psicosociales influyentes en la ocurrencia de accidentes laborales

El objetivo del trabajo es la presentación de un modelo de predicción de la siniestralidad laboral basado en datos empíricos en un conjunto de variables susceptibles de intervención. El método empleado es un diseño transversal y correlacional, en el que a partir de una muestra representativa de más de 500 trabajadores de diferentes sectores de actividad de la provincia de Valencia, se cuantifica la importancia relativa de cada uno de los aspectos definidos como relevantes para predecir la ocurrencia de accidentes. El uso metodológico de modelos de ecuaciones estructurales permite la consideración simultánea de un gran número de variables, junto con un adecuado control estadístico, reflejando así con mayor fidelidad la problemática de la siniestralidad laboral. Los resultados muestran el impacto de la variables organizacionales y los riesgos sobre variables del trabajador, la importancia de éstas en la predicción de accidentes, junto con su papel mediador en los efectos de las variables organizacionales (clima de seguridad, formación en seguridad, sobrecarga de trabajo, etc.) sobre la ocurrencia de accidentes laborales. La conclusión es que los aspectos psicosociales son claves en la explicación de los accidentes laborales y abren vías para una intervención efica

Retranslocament de nutrients en les fulles senescents de faig (Fagus sylvatica L.)

Nutrient (P. K. Ca and Mg) contents of leaves prior to senescence, nutrient return in leaf litterfall, and nutrient lcaching in throughfall were measured during October and November in a beech forest experimental plot in the Montseny Mountains (NE Spain). Only K was leached in significant amounts. Rctranslocation of P and K amounted to 46% and 13%. respectively. of the foliar nutrient contents before senescence. Calcium accumulated in the leaves during this period. while Mg showed no net retranslocation or accumulation. Retranslocated P can supply a large fraction of the annual P requirements of the trees. and contributes to keep a tight P cycle. However. the percentagc of P retranslocated in this forest lies in the lower range of literature values for forest ecosystems.Es mesuraren les mineralomasses foliars de P, K, Ca i Mg abans de la senescencia i el retorn de nutrients per la caiguda de fulles i per la lixiviació en el trascol durant octubre i novembre en una parcel4a experimental de la fageda de Santa Fe (Montseny, Barcelona). Només el K es lixivia en quantitats significatives. El retranslocament de P i K representi, respectivament, el 46% i el 13% de la mineralomassa foliar abans de la senescbncia. Les fulles acumularen Ca durant aquest període. mentre que el Mg no manifesta retranslocament ni acumulació nets. La quantitat de P retranslocada (1.4 kg ha-') pot subministrar una part important dels requeriments anuals de P del faig, i contribueix a mantenir un cicle tancat de P. No obstant, el percentatge de P retranslocat en aquest bosc es dels més baixos dels trobats a la bibliografia sobre ecosistemes forestals

Effects of reduced and conventional tillage on weed communities: Results of a long-term experiment in Southwestern Spain [Efeito do cultivo mínimo e plantio convencional em comunidades de plantas daninhas: Resultados de um experimento de longo prazo no sudoeste da espanha]

An important drawback in adopting minimum tillage (MT) and notillage (NT) techniques is the frequently observed weed shift promoting adapted species and achieving poorer weed control. These changes can be detected best with long-term experiments, and results might differ depending on soil characteristics and the local flora. The objectives of this work were to evaluate the effect of reduced tillage on weed seed distribution in the soil profile and to identify possible consequences on weed diversity on a long-term experiment maintained during 24 years in Seville (Spain) with three tillage systems: NT, MT and conventional tillage (CT) including moldboard plow on a vertisol. For this purpose, soil seedbanks at 0-8 cm and 8-16 cm depths were enumerated in autumn 2005 and in-field emerged plants in autumn 2005 and winter 2006. Shannon diversity index (H) and evenness (J’) were calculated for seedbank and aboveground weed communities. Total weed seed density was highest for NT and lowest for CT. Some big-seeded species, such as Chrozophora tinctorea L., showed highest seed density in CT. NT increased the relative density of Amaranthus blitoides S. Watson seeds in the seedbank and the abundance of emerged plants of Malva parviflora L., Anagallis arvensis L. and Picris echioides L. Overall, MT led to a less diverse seedbank in the 0-8 cm depth of soil than CT. The frequent drought-induced deep fractures in the expandable clay soil caused natural tillage, which probably resulted in fewer differences in weed seed and seedling densities among tillage treatments compared to what might be expected in other soil types

An efficient CDMA decoder for correlated information sources

We consider the detection of correlated information sources in the ubiquitous Code-Division Multiple-Access (CDMA) scheme. We propose a message-passing based scheme for detecting correlated sources directly, with no need for source coding. The detection is done simultaneously over a block of transmitted binary symbols (word). Simulation results are provided demonstrating a substantial improvement in bit-error-rate in comparison with the unmodified detector and the alternative of source compression. The robustness of the error-performance improvement is shown under practical model settings, including wrong estimation of the generating Markov transition matrix and finite-length spreading codes.Comment: 11 page

Inference by replication in densely connected systems

An efficient Bayesian inference method for problems that can be mapped onto dense graphs is presented. The approach is based on message passing where messages are averaged over a large number of replicated variable systems exposed to the same evidential nodes. An assumption about the symmetry of the solutions is required for carrying out the averages; here we extend the previous derivation based on a replica symmetric (RS) like structure to include a more complex one-step replica symmetry breaking (1RSB)-like ansatz. To demonstrate the potential of the approach it is employed for studying critical properties of the Ising linear perceptron and for multiuser detection in Code Division Multiple Access (CDMA) under different noise models. Results obtained under the RS assumption in the non-critical regime give rise to a highly efficient signal detection algorithm in the context of CDMA; while in the critical regime one observes a first order transition line that ends in a continuous phase transition point. Finite size effects are also observed. While the 1RSB ansatz is not required for the original problems, it was applied to the CDMA signal detection problem with a more complex noise model that exhibits RSB behaviour, resulting in an improvement in performance.Comment: 47 pages, 7 figure

Parametric model for the simulation of the railway catenary system static equilibrium problem

Dynamic simulations of pantograph catenary interaction are nowadays essential for improving the performance of railway locomotives, by achieving better current collection at higher speeds and lower wear of thecollecting parts.The first step in performing these simulations is to compute the static equilibrium of the overhead line.The initial dropper lengths play an important role in hanging the contact wire at an appropriate height. From a classical point of view, if one wants to obtain the static equilibrium configuration of the system for different combinations of dropper lengths, one static pro- blem must be solved for each combination of lengths, which involves a prohibitive computational cost. In this paper we propose a parametric model of the catenary, including the undeformed dropper lengths as extra-coordinates of the problem. This multidimensional problem is efficiently solved by means of the Proper Generalized Decomposition (PGD) technique, avoiding the curse of dimensionality issue. The capabilities and performance of the proposed method are shown by numerical examples.The authors would like to acknowledge the financial support of the FPU program offered by the Ministerio de Educacion, Cultura y Deporte under Grant number FPU13/04191. The funding from Universitat Politecnica de Valencia and Generalitat Valenciana (PROMETEO/2012/023) are also acknowledged.Gregori Verdú, S.; Tur Valiente, M.; Nadal, E.; Fuenmayor Fernández, FJ.; Chinesta, F. (2016). Parametric model for the simulation of the railway catenary system static equilibrium problem. Finite Elements in Analysis and Design. 115:21-32. https://doi.org/10.1016/j.finel.2016.02.007S213211

Formation and dissolution of inter-firm linkages in lengthy and stable networks in clusters

[EN] Firms aspire to take advantage of technical and business networks through inter-organizational interactions to improve performance. Consequently, researchers are increasingly focusing on the dynamics and implications of network formation at both local and global levels. The recent research trend does not consider a monotonic effect and simplistic approach to proximity because proximity is a complex multidimensional concept. Using data from a foodstuffs cluster in the Valencian region (Spain) and advanced econometric methods such as Exponential Random Graph Models, this study aims to clarify the detrimental effects and complementarities that may arise among proximity dimensions. After controlling for network endogenous forces and firm characteristics, findings reveal the negative effect of cognitive and institutional proximity dimensions on the creation of linkages in advanced stages of the cluster life cycle. Furthermore, social proximity and geographical proximity favor the formation of inter-firm relationships and reinforce the organizational dimension.The authors acknowledge the financial support of the Spanish Ministry of Economy and Competitiveness (Research Project Number ECO2012-32663 and Research Project Number ECO2010-2055).Molina Morales, FX.; Belso Martínez, JA.; Mas Verdú, F.; Martínez Cháfer, L. (2015). Formation and dissolution of inter-firm linkages in lengthy and stable networks in clusters. Journal of Business Research. 68(7):1557-1562. https://doi.org/10.1016/j.jbusres.2015.01.051S1557156268