911 research outputs found
CONSIDERING ANTI-PIRACY SHIP SECURITY: CITADEL DESIGN AND USE
As piracy continues to pose a threat to the shipping industry, a number of measures for protecting ships, cargo and crew will need to be implemented. Along with other steps, such as deploying military rescue teams, securing the crew within a ship’s citadel has proved to be a highly effective form of self-protection against hostage-taking by pirates. From a design standpoint, aspects that should be considered include the location and dimensions of the citadel, the maximum time crew can stay within it and the specific requirements for various elements of the ship or citadel equipment. Exploiting data on pirate attacks recently occurring in High Risk Areas, this article analyses the design and use of the citadel as a self-protection measure against piracy. As a conclusion, various requirements for these structures are recommended
Free amino acid composition in juveniles of Mytilus galloprovincialis: spatial variability after Prestige oil spill
10 páginas, 5 figuras, 2 tablasComposition of free amino acids (FAA) in juveniles of Mytilus galloprovincialis was analysed along a large geographical coastline area in
Galicia (NW Spain). Individuals were sampled in February 2003, three months after the Prestige oil spill. Pollution values at sampling time were
reported as polycyclic aromatic hydrocarbons (PAHs) concentrations in soft tissues of individuals and varied between the highest amount observed
in Carrumeiro mussels (502 ng/g dw) and the lowest in Pindo mussels (196 ng/g dw), both locations being close to each other in the centre of the
geographical area under study. Pollution values in the other populations varied within the range of 241–347 ng/g dw. Total free amino acids
(TFAA) were highest in Aguiño–Pindo–Carrumeiro juveniles at the centre of the Coastline area studied (420–462 μmol/g dw) as compared to the
other populations at North and South of Galicia (312–347 μmol/g dw). TFAA results were based on the variability observed in protein free amino
acids (PFAA μmol/g dw) among populations (214–249 μmol/g dw for Aguiño–Pindo–Carrumeiro mussels and 98–149 μmol/g dw for the other
populations) whereas non-protein free amino acids (NPFAA) taurine and ornithine did not show any significant spatial pattern of variation.
Glycine and alanine represented the most abundant PFAA (16–29% and 2.7–11.9% of TPFAA, respectively) and significant correlations between
PFAA and both the protein content of soft tissues (r=−0.82) and the condition index of juveniles (r=0.86) were observed. No significant
relationships were detected, however, between pollution values in soft tissues as PAHs and FAA profiles with the exception of alanine
concentrations as percentage of TFAA (r=0.88; P<0.01). The latter seemed to be an “all or nothing” effect likely due to the influence of other
abiotic factors at one of the sampling sites. Such relationship was found not significant when the outlier represented by Carrumeiro mussels was
removed from the analysis. The most abundant free amino acid taurine (43.2–68.5%TFAA) followed an inverse variability of that of glycine and
by extension of the group PFAA most likely as a compensatory decrease in mussel populations with low protein content (and high condition
index). Accordingly, taurine:glycine (t:g) ratio varied between 1 and 2 in most mussel populations but increased up to 3.2–4.2 in Miranda and
Bueu mussels at both ends of the geographical interval studied with a corresponding PAHs concentrations of 261 and 304 ng/g dw, respectively.
These mussel populations with the highest t:g ratios were characterised by the lowest PFAA contents (below 40%) and condition index values
(below 10%). Results of the present study established a significant link between energetic status of growing juveniles and FAA concentrations in
environments with different pollution degrees. Variability of the free amino acids profiles in soft tissues were related to endogenous factors of
juveniles (protein content, condition index) whereas no relationship with contamination values could be observed. The utility of t:g ratio as general
condition factor for M. galloprovincialis is also corroborated for in situ growing juveniles.This study was
supported by the contract-project PROINSA, Code CSIC 2004448,
Galicia PGDIT03RMA13E. JMFB acknowledges funding by the
Program Ramón y Cajal 2003 from Ministry of Education and
Sciences (Spain).Peer reviewe
Los primeros años de la reconstituida SEEC
Twenty years ago, in February 1994, the Spanish Comparative Pedagogy Society was substantially transformed, not only in its denomination but in the structure, modus operandi and concrete tasks. This paper, written in almost autobiographical way, aims to reflect the main reasons for such a change, as well as the life and evolution of the updated academic society during these first years of functioning, at the time in which the author assumed the presidency. Dealing with a lively chronicle of the mentioned period, the author implies also some of his main theoretical convictions concerning the comparative education field. En febrero de 1994, hace ahora 20 años, la Sociedad Española de Pedagogía Comparada (SEPC) operó una transformación en profundidad que no sólo afectaría a su nombre, sino muy especialmente a su tipología, a su modus operandi e incluso a la ejecución de nuevos objetivos y tareas. Este artículo, escrito en primera persona y de modo casi autobiográfico, desea reflejar cuáles fueron las razones del cambio y sobre todo la vida de la renovada asociación durante los primeros años, correspondientes al período de presidencia de su autor. Además de intentar una crónica vivida de la institución, el texto refleja también algunas de las principales convicciones que inspiraron las acciones de esa etapa.Twenty years ago, in February 1994, the Spanish Comparative Pedagogy Society was substantially transformed, not only in its denomination but in the structure, modus operandi and concrete tasks. This paper, written in almost autobiographical way, aims to reflect the main reasons for such a change, as well as the life and evolution of the updated academic society during these first years of functioning, at the time in which the author assumed the presidency. Dealing with a lively chronicle of the mentioned period, the author implies also some of his main theoretical convictions concerning the comparative education field
A new rebbachisaurid sauropod from the Aptian–Albian, Lower Cretaceous Rayoso Formation, Neuquén, Argentina
Rebbachisaurids are a group of basal diplodocimorph sauropods that diversified in Gondwana at the end of the Early
Cretaceous and the beginning of the Late Cretaceous. It is a group of great palaeobiogeographical interest, for it clearly
illustrates various processes of dispersal throughout Gondwana and to Laurasia prior to the breakup of Africa and South
America. However, the relationships within the group are still under discussion owing to the scarcity of cranial material
that would help clarify them. In the present paper we describe the new rebbachisaurid Lavocatisaurus agrioensis gen. et
sp. nov. from the Aptian–Albian (Lower Cretaceous) of Neuquén (Argentina). Remains have been recovered belonging
to an adult specimen (holotype) and two immature specimens (paratypes). Taken together, almost all the bones of the
taxon are represented, including most of the cranium. Lavocatisaurus agrioensis gen. et sp. nov. is the first rebbachisaurid
from Argentina with an almost complete cranium, making it possible to recognize differences with respect to
other rebbachisaurids, such as the highly derived Nigersaurus. Among its most notable characters are the presences of
a large preantorbital fenestra and maxillary teeth that are significantly larger than those of the dentary. Our phylogenetic
study places Lavocatisaurus amongst basal rebbachisaurids, as the sister lineage to Khebbashia (the clade formed by
Limaysaurinae + Rebbachisaurinae). This position, which is somewhat more derived than that previously suggested
for Comahuesaurus and Zapalasaurus (the Argentinean rebbachisaurids closest in geographical and geological terms),
reaffirms the presence of different basal rebbachisaurid lineages in the Early Cretaceous of Patagonia
The structure and ecological function of the interactions between plants and arbuscular mycorrhizal fungi through multilayer networks
Arbuscular mycorrhizas are one of the most frequent mutualisms in terrestrial
ecosystems. Although studies on plant mutualistic interaction networks suggest
that they may leave their imprint on plant community structure and dynamics,
this has not been explicitly assessed. Thus, in the context of plant-fungi
interactions,
studies explicitly linking plant-mycorrhizal
fungi interaction networks with
key ecological functions of plant communities, such as recruitment, are lacking.
2. In this study, we analyse, in two Mediterranean forest communities of southern
Iberian Peninsula, how plant-arbuscular
mycorrhizal fungi (AMF) networks
modulate plant-plant
recruitment interaction networks. We use a new approach
integrating plant-AMF
and plant recruitment networks into a single multilayer
structure. We also develop a new metric (Interlayer Node Neighbourhood
Integration, INNI) to explore the impact of a given node on the structure across
layers.
3. The similarity of plant species in their AMF communities is positively related to
the observed frequency of recruitment interactions in the field. Results reveal
that properties of plant-AMF
networks, such as plant degree and centrality, can
explain about the properties of plant recruitment network, such as in-and
out-degree
(i.e. sapling bank and canopy service) and its modular structure. However,
these relationships differed between the two forest communities. Finally, we
identify particular AMF that contribute to integrate the neighbourhood of recruitment
interactions between plants.
4. This multilayer network approach is useful to explore the role of plant-AMF
interactions
on recruitment, a key ecosystem function enhanced by fungi. Results
provide evidence that the complex structure of plant-AMF
interactions impacts
functional and structurally plant-plant
interactions, which in turn may potentiallyMinisterio de Ciencia e Innovación, Grant/
Award Number: CGL2015-69118-
C2-
2-
P
and PGC2018-100966-
B-
I0
A new species of Aquilegia (Ranunculaceae) from Sardinia (Italy)
The new species Aquilegia cremnophila (Ranunculaceae) from the Italian island of Sardinia is here described and illustrated. It occurs in shady rocky crevices, near the upper parts of Mt. Corrasi (Supramontes Region), where it is a member of chasmophilous communities. This species is morphologically, phenologically, ecologically and genetically well differentiated from the other Sardinian taxa, showing some relationships mainly with A. nugorensis, an endemic species of Central-Eastern Sardinia. Its conservation status is examined. A key of all taxa present in Sardinia is also provided. © 2012 Magnolia Press.Peer Reviewe
Uso De Un Polímero Hidrófilo A Base De Poliacrilamida Para Mejorar La Eficiencia En El Uso Del Agua
As an alternative in search of new options to reduce overexploitation of groundwater that allow us to increase agricultural profitability in water scarce areas, the behavior of a commercial hydrophilic polymer based in polyacrylamide (PAM) Lluvia solida®, was analyzed by evaluating the polymer hydration capacity. The tests that we used showed that this polymer is capable of absorbing its own weight in 268 times when using distilled water. When salts are dissolved in the water, the polymer reduces its water absorbing capacity, the hydration capacity being lower as the salt content increases, with a water absorption reduction up to 116 times its weight. The polymer hydration capacity also decreases significantly when a complete nutritive solution is used, reducing water absorption up to 55 times its weight; in the presence of divalent (Ca2+ and Mg2+) and monovalent (K+ and NH4 +) cations the polymer hydration capacity reduces proportionally to the cation concentration as an exponential function. Urea did not have any effect in the polymer hydration, thus this fertilizer may be used along with the polymer. The use of this hydrophilic polymer is a tool that improves the water use efficiency but the effect depends on water quality, being reduced by the presence of salts in water
Invasive species and habitat degradation in Iberian streams: An analysis of their role in freshwater fish diversity loss
Mediterranean endemic freshwater fish are among the most threatened biota in the world. Distinguishing the role of different extinction drivers and their potential interactions is crucial for achieving conservation goals. While some authors argue that invasive species are a main driver of native species declines, others see their proliferation as a co-occurring process to biodiversity loss driven by habitat degradation. It is difficult to discern between the two potential causes given that few invaded ecosystems are free from habitat degradation, and that both factors may interact in different ways. Here we analyze the relative importance of habitat degradation and invasive species in the decline of native fish assemblages in the Guadiana River basin (southwestern Iberian Peninsula) using an information theoretic approach to evaluate interaction pathways between invasive species and habitat degradation (structural equation modeling, SEM). We also tested the possible changes in the functional relationships between invasive and native species, measured as the per capita effect of invasive species, using ANCOVA. We found that the abundance of invasive species was the best single predictor of natives' decline and had the highest Akaike weight among the set of predictor variables examined. Habitat degradation neither played an active role nor influenced the per capita effect of invasive species on natives. Our analyses indicated that downstream reaches and areas close to reservoirs had the most invaded fish assemblages, independently of their habitat degradation status. The proliferation of invasive species poses a strong threat to the persistence of native assemblages in highly fluctuating environments. Therefore, conservation efforts to reduce native freshwater fish diversity loss in Mediterranean rivers should focus on mitigating the effect of invasive species and preventing future invasions
STUDIES OF SIMULATIONS OF TWO-PHASE WATER-AIR FLOWS USING ANSYS CFX.
Normally in all simulations of flows in computational fluid dynamics, CFD, it is common to use characteristic planes to visualize the profiles of the parameters of interest, mainly in 3D simulations.
The present work proposes a standard form of visualization that shows, mainly in two-phase flows, in a more realistic way, the dynamics of the development of the phase flow. This visualization is present within the CFX program in the post-processing module, in the option of representing volumes using sub option, isovolumes. Through this representation, the program highlights the volumes of the finite element mesh corresponding to the selected values of the parameter to be analyzed such as pressure, velocity, volumetric fraction, etc.
By means of the volume-isovolume representation, a well representative effect of the current flow pattern is obtained, especially when the volumetric fraction of the air or the gas phase of the flow is emphasized.
This form of visualization is being applied to the study of inclined two-phase flows, which will be tested in a new experiment currently under construction at the Laboratory of Experimental Thermal-Hydraulics – LTE of the Institute of Nuclear Engineering - IEN in Rio de Janeiro
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