146 research outputs found
First record of Caprella mutica from the Iberian Peninsula: expansion southwards in European waters
The caprellid amphipod, Caprella mutica, is a well-known invasive species, originating in the Sea of Japan, which has been rapidly expanding along the coasts of North America, Europe and Oceania for the last forty years. Caprella mutica is frequently associated with man-made structures, especially those dedicated to aquaculture activities, where it can reach high densities of up to 300,000 ind./m2. A well-established population of C. mutica was recently found by SCUBA-divers in Galician waters (north-west Spain) at 6 different man-made floating structures along Ría de Arousa. The record of this species in this location implies a new southernmost limit of distribution, extending the known distribution range in Atlantic European waters and confirming the continuity of the colonization southwards
Instabilities and turbulence in stellarators from the perspective of global codes
In this work, a comparison of the global gyrokinetic codes EUTERPE and
GENE-3D in stellarator configurations of LHD and W7-X is carried out. In linear
simulations with adiabatic electrons, excellent agreement is found in the mode
numbers, growth rate and frequency, mode structure, and spatial localization of
the most unstable mode in LHD. In W7-X, the dependence of the growth rate and
frequency with the mode number is well reproduced by both codes. The codes are
also compared in linear simulations with kinetic ions and electrons in W7-X
using model profiles, and reasonable agreement is found in the wavenumber of
the most unstable modes. A stabilization of small-scale modes in
kinetic-electron simulations with respect to the adiabatic-electron case is
consistently found in both codes. Nonlinear simulations using adiabatic
electrons and model profiles are also studied and the heat fluxes are compared.
Very good agreement is found in the turbulent ion heat fluxes in both LHD and
W7-X. Two problems that cannot be properly accounted for in local flux tube
codes are studied: the localization of instabilities and turbulence over the
flux surface and the influence of a background long-wavelength electric field.
Good agreement between codes is found with respect to the spatial localization
of instabilities and turbulence over the flux surface. The localization of
saturated turbulence is found in both codes to be much smaller than that of the
linear instabilities and smaller than previously reported in full-surface
radially-local simulations. The influence of the electric field on the
localization is also found to be smaller in the developed turbulent state than
in the linear phase, and smaller than in previous works. A stabilizing effect
of a constant electric field on the linearly unstable modes is found in both
codes. A moderate reduction of turbulent transport by the radial electric
field..
Effects of salinity and B excess on the growth, photosynthesis, water relation and mineral composition of laurustinus grown in greenhouse
Trabajo presentado en el XXVIII International Horticultural Congress on Science and Horticulture for People (IHC2010): International Symposium on Greenhouse 2010 and Soilless Cultivation, celebrado en Lisboa, Portugal, del 22 al 27 de agosto de 2010A greenhouse study was conducted to determine the interactive effects of NaCl
salinity and boron on the growth, plant water status, gas exchange, chlorophyll
fluorescence and concentrations of sodium (Na), chloride (Cl) and boron (B) in
laurustinus (Viburnum tinus L.). Potted plants were grown in a factorial
combination of salinity (2 and 6 dS m-1) and boron (1 and 6 mg L-1). Plant dry
weight (DW) decreased with salinity and B excess, particularly as a result of the
former. The salinity × B interaction on the plant DW was not significant (additive
effects). Salinity increased Na and Cl concentrations in leaf (20 and 35 mg g-1 DW,
respectively) resulting in foliar injury. The application of 6 mg L-1 of B (B toxicity or
B excess) produced injury symptoms in old leaves (leaf tip and edge burn). Salinity
and B toxicity led to leaves dropping, especially the former. B toxicity led to higher B
concentrations in insured leaves (1385 mg kg-1 DW) and salinity reduced it to 425 (B
x NaCl antagonistic effect). Boron excess did no alter Na and Cl concentrations in
leaf. Salinity decreased stomatal conductance (gs) as a regulatory mechanism against
osmotic stress, which resulted in a dropping photosynthesis (Pn). Leaf water
parameters were only affected by salinity, which enhanced a process of osmotic
adjustment and improving the plant water status. Salt-stressed plants showed an
adaptive response to salinity, which decreased gs, Pn and quantum yield of
photosystem II (éPSII), and dissipated the excess radiant energy as heat (increased
non-photochemical quenching [NPQ]). The combination of salinity and B excess
maintained éPSII and decreased the effectiveness of stomatal regulation, NPQ and
Pn. This caused the lowest plant DW and suggests disorders in electron transport
(photorespiration). Our findings suggest that: (1) laurustinus is a B excess sensitive
species, (2) salinity reduced the accumulation of B in leaves of the B excess stressed
plants but was not enough to prevent injuries in PSII, and (3) B excess or/and
salinity provide plants of poor commercial quality.This research was supported by CICYT projects (CICYT AGL2008-05258-CO2-
1-AGR and CICYT AGL2008-05258-CO2-2-AGR), SENECA project (08669/PI/08) and
by the Consejería de Agricultura y Agua de la Región de Murcia, program (UPCTCEBAS-
IMIDA 2008).Peer Reviewe
Maritime antarctic lakes as sentinels of climate change
Remote lakes, such as lakes from the Maritime Antarctica, can be used as sentinels of climate change, because
they are mostly free of direct anthropogenic pressures, and they experience climate change as a main stressor
capable of modifying the ecosystem structure and function. In this paper, the content of a lecture that has been
presented at the First Conference of Lake Sustainability, which has been centred in our studies on lakes from
Byers Peninsula (Maritime Antarctica), are summarized. These included physical, chemical and biological
studies of these lakes and other freshwater ecosystems, which highlighted the relevance of biotic interactions
for these ecosystems and its sensibility to temperature variations and to biological invasions, which is of rel-
evance given the acute regional warming occurring during the last decades in the area, concomitant with the
enhancement of dispersion of alien species linked to the increased presence of humans
ONTOGENERATION: Reusing Domain and Linguistic Ontologies for Spanish Text Generation
A significant problem facing the reuse of ontologies is to make their content more widely accessible to any potential user. Wording all the information represented in an ontology is the best way to ease the retrieval and understanding of its contents. This article proposes a general approach to reuse domain and linguistic ontologies with natural language generation technology, describing a practical system for the generation of Spanish texts in the domain of chemical substances. For this purpose the following steps have been taken: (a) an ontology in the chemicals domain developed under the METHONTOLOGY framework and the Ontology Design Environment (ODE) has been taken as knowledge source; (b) the linguistic ontology GUM (Generalized Upper Model) used in other languages has been extended and modified for Spanish; (c) a Spanish grammar has been built following the systemic-functional model by using the KPML (Komet-Penman Multilingual) environment. As result, the final system named Ontogeneration permits the user to consult and retrieve all the information of the ontology in Spanish
Ontogeneration: Arquitectura basada en ontologías para la generación de textos en castellano
En este trabajo se presenta Ontogeneration, una arquitectura para generar textos en castellano utilizando ontologías lingüísticas y de dominio con la tecnología KPML de generación de lenguaje natural. Además se ha construido un sistema que genera textos en castellano en el dominio de las sustancias químicas. Para alcanzar tales resultados, se han seguido los siguientes pasos: a) se ha tomado como fuente de conocimiento una ontología en el dominio químico construida usando la metodología de desarrollo de ontologías llamada METHONTOLOGY y el Entorno de Diseño de Ontologías (Ontology Design Environment: ODE), b) se ha extendido y modificado la ontología lingüística GUM (Generalized Upper Model) para el castellano, c) se ha construido una gramática para el castellano siguiendo el modelo sistémico-funcional usando el entorno KPML (Komet Penman Multilingual). Se consigue, así, que los contenidos almacenados en la ontología de dominio sean accesibles por usuarios legos en la materia
Nuevos datos sobre la presencia de especies nuevas o poco conocidas de la ictiofauna marina de Galicia (II)
La bibliografía ictiológica de Galicia tiene
una larga historia que ha ido enriqueciéndose
con sucesivas aportaciones. Durante los últimos
años, una mayor atención científica y el estrecho
contacto con el sector pesquero, han permitido
mejorar el conocimiento de la ictiofauna marina
de Galicia, dando lugar al registro de especies
nuevas para aguas gallegas y europeas (Bañón,
2002; Bañón et al., 2007) y a la confirmación de
la presencia de especies citadas anteriormente.
En este trabajo se establecen seis nuevas citas
sobre la presencia de especies nuevas o poco
conocidas para las aguas de Galicia: Anjova
Pomatomus saltatrix (Linnaeus, 1766) (Pomatomatidae),
Jurelo negro Trachurus picturatus
(Bowdich, 1825) (Carangidae), Palometa blanca
Trachinotus ovatus (Linnaeus, 1758), pez volador
Cheilopogon heterurus. (Rafinesque, 1810),
Linterna negra Benthosema glaciale (Reinhardt,
1838) y Limanda noruega Phrynorhombus norvegicus
(Günther, 1862) (Scophthalmidae)
Gyrokinetic simulations in stellarators using different computational domains
In this work, we compare gyrokinetic simulations in stellarators using
different computational domains, namely, flux tube, full-flux-surface, and
radially global domains. Two problems are studied: the linear relaxation of
zonal flows and the linear stability of ion temperature gradient (ITG) modes.
Simulations are carried out with the codes EUTERPE, GENE, GENE-3D, and stella
in magnetic configurations of LHD and W7-X using adiabatic electrons. The zonal
flow relaxation properties obtained in different flux tubes are found to differ
with each other and with the radially global result, except for sufficiently
long flux tubes, in general. The flux tube length required for convergence is
configuration-dependent. Similarly, for ITG instabilities, different flux tubes
provide different results, but the discrepancy between them diminishes with
increasing flux tube length. Full-flux-surface and flux tube simulations show
good agreement in the calculation of the growth rate and frequency of the most
unstable modes in LHD, while for W7-X differences in the growth rates are found
between the flux tube and the full-flux-surface domains. Radially global
simulations provide results close to the full-flux-surface ones. The radial
scale of unstable ITG modes is studied in global and flux tube simulations
finding that in W7-X, the radial scale of the most unstable modes depends on
the binormal wavenumber, while in LHD no clear dependency is found.Comment: submitted to Nuclear Fusio
Shedding light on the Holocephali taxonomy, the mitogenome of Chimaera opalescens
Cartilaginous fish (Chondrichthyes), i.e. sharks, rays, and chimaeras, are extremely interesting from a biological perspective as they represent one of the oldest and most ecologically diverse groups of jawed vertebrates. Their K-selective reproductive traits, make them vulnerable to overfishing. Chimaerid are also a frequent by-catch of deep-water fisheries. Holocephalans comprise a single surviving order, the Chimaeriformes, and are allocated into three different families: Callorhinchidae, Rhinochimaeridae and Chimaeridae (Weigmann 2016). Furthermore, the family Chimaeridae only includes two genera: Chimera and Hydrolagus. Recently, several new species have been described (Iglesias et al., 2022), including Chimera opalescens from deep-sea assemblages (Luchetti et al., 2011). However, previous records of C. opalescens were erroneously classified as Chimera monstrosa (Luchetti et al., 2011; Catarino et al., 2020), due to the similar morphology (Luchetti et al., 2011), which highlights the critical importance of molecular approaches to support species identification. Mitogenomes have been a powerful tool used to elucidate phylogenetic relationships, both at deep and at shallow evolutionary nodes. The development of long-read sequencing technologies a precise and reliable assembly of complete mtDNA genomes. The sequencing and characterization of the complete mitogenome of the opal chimera Chimera opalescens (Luchetti, Iglesias et al., 2011) was carried out, using the long-read technique PacBio HiFi. The entire mitogenome was 23,411 bp long and shows the same overall content, i.e. 13 protein-coding genes, 22 transfer RNA and 2 ribosomal RNA genes, as all other examined chondrichthyan mitogenomes. Phylogenetic reconstructions using all available Chondrichthyan mitogenomes, including 11 Holocephali (chimeras and ratfishes), places C. opalescens within the Chimaeridae family. Furthermore, the results reinforce previous findings, showing the genus Chimera as paraphyletic and thus highlighting the need to expand molecular approaches in this group of cartilaginous fishes
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