Colour valued Scattering Matrices

We describe a general construction principle which allows to add colour values to a coupling constant dependent scattering matrix. As a concrete realization of this mechanism we provide a new type of S-matrix which generalizes the one of affine Toda field theory, being related to a pair of Lie algebras. A characteristic feature of this S-matrix is that in general it violates parity invariance. For particular choices of the two Lie algebras involved this scattering matrix coincides with the one related to the scaling models described by the minimal affine Toda S-matrices and for other choices with the one of the Homogeneous sine-Gordon models with vanishing resonance parameters. We carry out the thermodynamic Bethe ansatz and identify the corresponding ultraviolet effective central charges.Comment: 8 pages Latex, example, comment and reference adde

Do process innovations boost SMEs productivity growth?

In this paper we explore in depth the effect of process innovations on total factor productivity growth for small and medium enterprises (SMEs), taking into account the potential endogeneity problem that may be caused by self selection into these activities. First, we analyse whether the ex-ante most productive SMEs are those that start introducing process innovations; then, we test whether process innovations boost SMEs productivity growth using matching techniques to control for the possibility that selection into introducing process innovations may not be a random process. We use a sample of Spanish manufacturing SMEs for the period 1991-2002, drawn from the Encuesta sobre Estrategias Empresariales. Our results show that the introduction of process innovations by a first-time process innovator yields an extra productivity growth as compared to a non-process innovator, and that the life span of this extra productivity growth has an inverted U-shaped form. En este artículo se exploran los posibles efectos de la introducción de innovaciones de proceso en el crecimiento de la productividad de las pequeñas y medianas empresas (PYMES). Para ello se presta especial atención a la existencia de un problema de selección no aleatorio en la implementación de tales innovaciones. En primer lugar, se analiza si son aquellas empresas ex-ante más productivas las que introducen innovaciones de proceso. A continuación, se utilizan técnicas de matching para contrastar si la implementación de innovaciones de proceso acelera el crecimiento de la productividad de las PYMES. La utilización de técnicas de matching permite controlar la posible existencia de un proceso de selección no aleatorio en la implementación de innovaciones de proceso. El análisis empírico se lleva cabo usando una muestra de PYMES manufactureras españolas extraída de la Encuesta sobre Estrategias Empresariales. Nuestros resultados muestran que la implementación de innovaciones de proceso por parte de PYMES sin experiencia previa en la introducción de tales innovaciones, produce un crecimiento extra de la productividad de estas PYMES en comparación con el de aquellas PYMES que no implementan innovaciones de proceso. Adicionalmente, nuestros resultados sugieren la existencia de una relación en forma de U invertida entre el crecimiento extra de la productividad y el tiempo transcurrido desde la introducción de la innovación de proceso.innovaciones de proceso, PTF, dominancia estocástica, técnicas de matching. process innovations, TFP, stochastic dominance, matching techniques.

Low-order harmonic generation in a ZnS laser ablation plasma

Low-order (3rd to 9th) harmonic generation of a near-infrared driving laser (1064 nm) is reported in a laser ablation plasma of ZnS. Temporal analysis shows two distinct components with respect to the ablation event. The late temporal component exhibits high conversion efficiency for the highest harmonic orders observed. This is attributed to a dramatic modification of the plasma medium with the driving laser.Peer Reviewe

‘Omics’ approaches for crop improvement

The growing human population and climate change are imposing unprecedented challenges on the global food supply [1]. To cope with these pressures, crop improvement demands enhancing important agronomical traits beyond yield, such as adaptation, resistance, and nutritional value, by pivoting direct and indirect selection approaches [2]. The development of next-generation high-throughput screening technologies, referred to as ‘omics’, promises to speed up plant trait improvement [3] while producing more sustainable crops. Large-scale techniques, such as genomics, transcriptomics, proteomics, metabolomics, and phenomics, have already provided large datasets for that purpose. Meanwhile, modern bioinformatic and machine-learning approaches are helping us to process this heterogeneous hyper-dimensional data [4] while ultimately understanding the mechanisms behind agronomic features within the contemporary plant breeding triangle (i.e., genomics vs. phenomics vs. enviromics) [5]. ‘Omics’ datasets are also being generated to study macro-scale interactions and deepen our knowledge of crop behavior across the microbial [6] and environmental [7,8] continua. However, despite these massive technological and computational developments [4], systemic efforts to integrate ‘omics’ studies to understand biochemical pathways and cellular networks of crop systems are in their infancy [9], especially in orphan species [10]. Therefore, this Special Issue envisions offering updated emergent views on large-scale ‘omics’-based approaches. Specifically, the compilation explores the conceptual framework of the ‘omics’ paradigm [11], the practical uses of multiple ‘omics’ technologies, and their integration through trans-disciplinary bioinformatics as tools to improve qualitative and quantitative traits in a diverse panel of crop species

Disparate dispersal limitation in Geomalacus slugs unveiled by the shape and slope of the genetic–spatial distance relationship

Long‐term dispersal ability is a key species’ trait constraining species ranges and thus large‐scale biodiversity patterns. Here we infer the long‐term dispersal abilities of three Geomalacus (Gastropoda, Pulmonata) species from their range‐wide genetic–spatial distance relationships. This approach follows recent advances in statistical modelling of the analogous pattern at the community level: the distance decay in assemblage similarity. While linear relationships are expected for species with high long‐term dispersal abilities, asymptotic relationships are expected for those with more restricted mobility. We evaluated three functional forms (linear, negative exponential and power‐law) for the relationship between genetic distance (computed from mitochondrial cox1 sequences, n = 701) and spatial distance. Range fragmentation at present time and at the Last Glacial Maximum was also estimated based on the projection of climatic niches. The power‐law function best fit the relationship between genetic and spatial distances, suggesting strong dispersal limitation and long‐term population isolation in all three species. However, the differences in slope and explained variance pointed to disparities in dispersal ability among these weak dispersers. Phylogeographic patterns of Geomalacus species are thus largely driven by the same major process (i.e. dispersal limitation), operating at different strengths. This strong dispersal limitation results in geographic clustering of genetic diversity that makes these species highly vulnerable to genetic erosion due to climate changThe authors were supported by the Spanish Ministry of Economy and Competitiveness and the European Regional Development Fund (ERDF) through grant CGL2016‐76637‐P and fellowship IJCI‐2014‐20881 to CG‐RS

Sea Level in the Strait of Gibraltar: Tides

A network of tide gauges with eight observation recording points was in operation in the Strait of Gibraltar during the years 1984 and 1985, which made it possible to draw up detailed charts of the tides showing their refined structure. For the first order, the Strait of Gibraltar represents the nodal line of the stationary wave of the western Mediterranean, which, hypothetically, would end at the Cadiz meridian (6°17.0W). The tide is basically semi-diurnal; on average, 90% of the energy is associated with the second order and, for this, the Strait of Gibraltar tends to represent an antinode of the stationary wave, although the influence of the bottom topography and the rotation is interpreted in phase delays in the sill area (slightly progressive wave) and in increased non-linear constituents of higher orders. The radiational tide S is evaluated in the area studied and it is ascertained that it shows the same characteristics as the tides having strictly gravitational constituents, which implies that it is fundamentally co-oscillating. Order 4 displays characteristics of resonant amplification due to the existence of the free oscillation mode of the western Mediterranean basin the period of which is close to 6 hours. Of order 3 it should be stressed that M3, though small, is perfectly detectable in the area

Harmonic generation by atomic and nanoparticle precursors in a ZnS laser ablation plasma

Harmonic generation of a driving laser propagating across a laser ablation plasma serves for the diagnosis of multicomponent plumes. Here we study the contribution of atomic and nanoparticle precursors to the generation of coherent ultraviolet and vacuum ultraviolet light as low-order harmonics of the fundamental emission (1064 nm) of a Q-switched Nd:YAG laser in a nanosecond infrared ZnS laser ablation plasma. Odd harmonics from the 3rd up to the 9th order (118.2 nm) have been observed with distinct temporal and spatial characteristics which were determined by varying the delay between the ablation and driving nanosecond pulses and by spatially scanning the plasma with the focused driving beam propagating parallel to the target. At short distances from the target surface (≤1 mm), the harmonic intensity displays two temporal components peaked at around 250 ns and 10 μs. While the early component dies off quickly with increasing harmonic order and vanishes for the 9th order, the late component is notably intense for the 7th harmonic and is still clearly visible for the 9th. Spectral analysis of spontaneous plume emissions help to assign the origin of the two components. While the early plasma component is mainly constituted by neutral Zn atoms, the late component is mostly due to nanoparticles, which upon interaction with the driving laser are subject to breakup and ionization. With the aid of calculations of the phase matching integrals within the perturbative model of optical harmonic generation, these results illustrate how atom and nanoparticle populations, with differing temporal and spatial distributions within the ablation plasma, contribute to the nonlinear medium.Funding has been provided by Ministerio de Economía y Competitividad (MINECO) of Spain under Project CTQ2013-43086-P. I.L-Q., A.B-C. and M.O. thank respectively MINECO, for a FPI fellowship (BES-2011-044738), CSIC, for a JAE-TEC 2010 contract and CSIC for a contract. Fruitful discussions with Dr. Mikel Sanz and Prof. A. Gonzalez-Arroyo are acknowledged.Peer reviewe

New views on old hands: the context of stencils in El Castillo and La Garma Caves (Cantabria, Spain)

Hand stencils are an intriguing feature of prehistoric imagery in caves and rockshelters in several parts of the world, and the recent demonstration that the oldest of those in Western Europe date back to 37 000 years or earlier further enhances their significance. Their positioning within the painted caves of France and Spain is far from random, but responds to the shapes and fissures in the cave walls. Made under conditions of low and flickering light, the authors suggest that touch—‘palpation’—as much as vision, would have driven and directed the locations chosen for these stencils. Detailed study of the images in two Cantabrian caves also allows different individuals to be distinguished, most of whom appear to have been female. Finally, the project reveals deliberate associations between the stencils and features on the cave walls