Search results for "structures"
showing 10 items of 4815 documents
Isolation of a new serovar of Vibrio vulnificus pathogenic for eels cultured in freshwater farms
2003
The present work reports the isolation of a new serovar of Vibrio vulnificus pathogenic for eels cultured in freshwater farms. This serovar, named Serovar A, produced two outbreaks of low morbidity and mortality in one Spanish eel farm in September 2000 and March 2001. The vibriosis affected healthy eels, weighting between 10 and 100 g, that had been vaccinated against the serovar E of the species (formerly biotype 2) at least 6 months before. Some of the diseased eels showed symptoms different to those reported for the classical vibriosis due to serovar E. These symptoms included bleeding ventral ulcers together with haemorrhagic intestine. Bath experimental challenges demonstrated that (i…
Comparative Analysis of Natural Gas Pipeline Interconnections
2021
The paper shows a comparison between two intervention methods for interconnecting two gas transmission pipelines within a natural gas transmission system. One intervention implies shutdown of pipelines, while the other one in-service pipelines. Each method is described in detail along with the main technological issues, as well as the related advantages and disadvantages. The technological procedures imply special working techniques such as welding or hot tapping in service pipelines.
Semidirect products of internal groupoids
2010
We give a characterization of those finitely complete categories with initial object and pushouts of split monomorphisms that admit categorical semidirect products. As an application we examine the case of groupoids with fixed set of objects. Further, we extend this to the internal case. (C) 2010 Elsevier B.V. All rights reserved.
The rise of thermophilic sea urchins and the expansion of barren grounds in the Mediterranean Sea
2011
Recent ecological studies have shown a strong relation between temperature, echinoids and their grazing effects on macro-algal communities. In this study, we speculate that climate warming may result in an increasingly favourable environment for the reproduction and development of the sea urchin Arbacia lixula. The relationship between increased A. lixula density and the extent of barren grounds in the Mediterranean Sea is also discussed.
Use of fresh vegetable discards as sea urchin diet: effect on gonad index and quality
2014
This study evaluated the exploitation of unprocessed agricultural discards in the form of fresh vegetable leaves as a diet for the sea urchin Paracentrotus lividus through the assessment of their effects on gonad yield and quality. A stock of wild-caught P. lividus was fed on discarded leaves from three different species (Beta vulgaris, Brassica oleracea, and Lactuca sativa) and the macroalga Ulva lactuca for 3 months under controlled conditions. At the beginning and end of the experiment, total and gonad weight were measured, while gonad and diet total carbon (C%), nitrogen (N%), δ13C, δ15N, carbohydrates, lipids, and proteins were analyzed. The results showed that agricultural discards pr…
Lipid and fatty acid biomarkers as proxies for environmental contamination in caged mussels Mytilus galloprovincialis
2015
Mussels (Mytilus galloprovincialis) were transplanted from a reference site (Syracuse harbour) to an impacted site (Augusta Bay) from January to July 2013 to assess the biochemical response of caged mus- sels to high trace element and polycyclic aromatic hydrocarbon (PAH) contamination, using lipid and fatty acid (FA) biomarkers. Sediment and mussels were analysed to assess contaminant bioavailability in the study sites and bioaccumulation in mussel tissue. Trace elements (As, Cd, Co, Cr, Cu, Hg, Mn, Ni, Pb, V, Zn) and PAHs were significantly higher in mussels from Augusta than in those from Syracuse, mirror- ing the different environmental contamination. The biological impact quotient (BIQs…
Crushing predation of the spiny star Marthasterias glacialis upon the sea urchin Paracentrotus lividus
2009
Literature data report that only fish predators are able to crush sea urchin tests in Mediterranean rocky reefs. This experimental study showed that the spiny star Marthasterias glacialis is able to break Paracentrotus lividus tests and that the breaking event is more likely to occur for small-sized sea urchins than for big ones. Our results show that the role of M. glacialis in regulating P. lividus population density can be important in specific locations. They may have important implications, moreover, for the use of tethering techniques aimed at identifying predator types of sea urchins.