Study of the infrastructures and the fishing power in Gran Canaria

Máster en Gestión Sostenible de Recursos Pesqueros

An analysis of an international fishery: introduction to a fishery management strategy compatible with the fishing sector

Máster en Gestión Sostenible de Recursos Pesqueros

Analisi dell'efficienza del chelante EDTA per l'estrazione di metalli pesanti da lisciviati di fly ash prodotte da termovalorizzatori

Si è valutata l'efficienza di estrazione di metalli pesanti (Al, Zn, Pb, V, Cr, Cu, Ti, Co, Cd, Ni) da soluzioni ottenute da leaching acido di fly ash da termovalorizzatore. L'efficienza è stata stimata in funzione del pH e del tempo (esperimenti di 24 h e 3 h) e tramite l'utilizzo di un agente chelante (EDTA). Si è dimostrata l'efficienza dell'esperimento di 3 h, che si traduce in un beneficio economico in quanto si ottiene un elevato grado di estrazione in minor tempo.

Characterization of a Coal Fly Ash-Cement Slurry by the Absolute Foam Index

This dissertation established a standard foam index: the absolute foam index test. This test characterized a wide range of coal fly ash by the absolute volume of air-entraining admixture (AEA) necessary to produce a 15-second metastable foam in a coal fly ash-cement slurry in a specified time. The absolute foam index test was used to characterize fly ash samples having loss on ignition (LOI) values that ranged from 0.17 to 23.3 %wt. The absolute foam index characterized the fly ash samples by absolute volume of AEA, defined as the amount of undiluted AEA solution added to obtain a 15-minute endpoint signified by 15-second metastable foam. Results were compared from several foam index test time trials that used different initial test concentrations to reach termination at selected times. Based on the coefficient of variation (CV), a 15-minute endpoint, with limits of 12 to 18 minutes was chosen. Various initial test concentrations were used to accomplish consistent contact times and concentration gradients for the 15-minute test endpoint for the fly ash samples. A set of four standard concentrations for the absolute foam index test were defined by regression analyses and a procedure simplifying the test process. The set of standard concentrations for the absolute foam index test was determined by analyzing experimental results of 80 tests on coal fly ashes with loss on ignition (LOI) values ranging from 0.39 to 23.3 wt.%. A regression analysis informed selection of four concentrations (2, 6, 10, and 15 vol.% AEA) that are expected to accommodate fly ashes with 0.39 to 23.3 wt.% LOI, depending on the AEA type. Higher concentrations should be used for high-LOI fly ash when necessary. A procedure developed using these standard concentrations is expected to require only 1-3 trials to meet specified endpoint criteria for most fly ashes. The AEA solution concentration that achieved the metastable foam in the foam index test was compared to the AEA equilibrium concentration obtained from the direct adsorption isotherm test with the same fly ash. The results showed that the AEA concentration that satisfied the absolute foam index test was much less than the equilibrium concentration. This indicated that the absolute foam index test was not at or near equilibrium. Rather, it was a dynamic test where the time of the test played an important role in the results. Even though the absolute foam index was not an equilibrium condition, a correlation was made between the absolute foam index and adsorption isotherms. Equilibrium isotherm equations obtained from direct isotherm tests were used to calculate the equilibrium concentrations and capacities of fly ash from 0.17 to 10.5% LOI. The results showed that the calculated fly ash capacity was much less than capacities obtained from isotherm tests that were conducted with higher initial concentrations. This indicated that the absolute foam index was not equilibrium. Rather, the test is dynamic where the time of the test played an important role in the results. Even though the absolute foam index was not an equilibrium condition, a correlation was made between the absolute foam index and adsorption isotherms for fly ash of 0.17 to 10.5% LOI. Several batches of mortars were mixed for the same fly ash type increasing only the AEA concentration (dosage) in each subsequent batch. Mortar air test results for each batch showed for each increase in AEA concentration, air contents increased until a point where the next increase in AEA concentration resulted in no increase in air content. This was maximum air content that could be achieved by the particular mortar system; the system reached its air capacity at the saturation limit. This concentration of AEA was compared to the critical micelle concentration (CMC) for the AEA and the absolute foam index.

In silico target fishing for rationalized ligand discovery exemplified on constituents of Ruta graveolens

The identification of targets whose interaction is likely to result in the successful treatment of a disease is of growing interest for natural product scientists. In the current study we performed an exemplary application of a virtual parallel screening approach to identify potential targets for 16 secondary metabolites isolated and identified from the aerial parts of the medicinal plant RUTA GRAVEOLENS L. Low energy conformers of the isolated constituents were simultaneously screened against a set of 2208 pharmacophore models generated in-house for the IN SILICO prediction of putative biological targets, i. e., target fishing. Based on the predicted ligand-target interactions, we focused on three biological targets, namely acetylcholinesterase (AChE), the human rhinovirus (HRV) coat protein and the cannabinoid receptor type-2 (CB (2)). For a critical evaluation of the applied parallel screening approach, virtual hits and non-hits were assayed on the respective targets. For AChE the highest scoring virtual hit, arborinine, showed the best inhibitory IN VITRO activity on AChE (IC (50) 34.7 muM). Determination of the anti-HRV-2 effect revealed 6,7,8-trimethoxycoumarin and arborinine to be the most active antiviral constituents with IC (50) values of 11.98 muM and 3.19 muM, respectively. Of these, arborinine was predicted virtually. Of all the molecules subjected to parallel screening, one virtual CB (2) ligand was obtained, i. e., rutamarin. Interestingly, in experimental studies only this compound showed a selective activity to the CB (2) receptor ( Ki of 7.4 muM) by using a radioligand displacement assay. The applied parallel screening paradigm with constituents of R. GRAVEOLENS on three different proteins has shown promise as an IN SILICO tool for rational target fishing and pharmacological profiling of extracts and single chemical entities in natural product research.

Cryptic invertebrates on subtidal rocky reefs vary with microhabitat structure and protection from fishing

The deployment of flat concrete blocks on subtidal rocky reefs can replicate natural reef microhabitats and provides a means for standardized sampling of cryptic invertebrates. The shape of the cavity beneath the block is related to reef topography and may influence the invertebrate community by affecting the amount of space for cryptic fauna to colonise and influencing the effectiveness of their predator-defence mechanisms. To determine the effect of sub-block reef structure and different levels of external predators on cryptic molluscs and echinoderms, I deployed concrete blocks at locations inside and outside the Maria Island marine reserve in eastern Tasmania, Australia. Relationships between sub-block reef structure and the cryptic invertebrate assemblage were evident between locations, whereas only a small but significant proportion of variation of assemblages between blocks within location was explained by reef surface area. No clear association with external predation pressure was evident in multivariate analyses of variation in assemblage structure. Juvenile abalone Haliotis rubra were not influenced by micro-habitat structure but were significantly less abundant at protected locations, the only species to exhibit such a response. This result follows a decline of emergent adult abalone in the marine reserve and raises the possibility of recruitment failure of abalone at some fully protected locations in the longer term.

Simulation of the Impact of Dams and Fishing Weirs on Reproductive Potential of Silver-Phase American Eels in the Kennebec River Basin, Maine

I modeled the cumulative impact of hydroelectric projects with and without commercial fishing weirs and water-control dams on the production, survival to the sea, and potential fecundity of migrating female silver-phase American eels, Anguilla rostrata in the Kennebec River basin, Maine, This river basin has 22 hydroelectric projects, 73 water-control dams, and 15 commercial fishing weir sites. The modeled area included an 8,324 km(2) segment of the drainage area between Merrymeeting Bay and the upper limit of American eel distribution in the basin. One set of input,, (assumed or real values) concerned population structure (Le., population density and sex ratio changes throughout the basin, female length-class distribution, and drainage area between dams), Another set concerned factors influencing survival and potential fecundity of migrating American eels (i.e., pathway sequences through projects, survival rate per project by length-class. and length-fecundity relationship). Under baseline conditions about 402,400 simulated silver female American eels would be produced annually reductions in their numbers due to dams and weirs would reduce the realized fecundity (i.e., the number of eggs produced by all females that survived the migration). Without weirs or water-control dams, about 63% of the simulated silverphase American eels survived their freshwater spawning migration run to the sea when the survival rate at each hydroelectric dam was 9017, 40% survived at 80% survival per dam, and 18% survived at 60% survival per dam. Removing the lowermost hydroelectric dam on the Kennebec River increased survival by 6.0-7.6% for the basin. The efficient commercial weirs reduced survival to the sea to 69-76%( of what it would have been without weirs', regardless of survival rates at hydroelectric dams. Water-control dams had little impact on production in this basin because most were located in the upper reaches of tributaries. Sensitivity analysis led to the conclusion that small changes in population density and female length distribution had greater effects on survival and realized fecundity than similar changes in turbine survival rate. The latter became more important as turbine survival rate decreased. Therefore, it might be more fruitful to determine population distribution in basins of interest than to determine mortality rate at each hydroelectric project.

A Normative Theory of Forgetting: Lessons from the Fruit Fly

Recent experiments revealed that the fruit fly Drosophila melanogaster has a dedicated mechanism for forgetting: blocking the G-protein Rac leads to slower and activating Rac to faster forgetting. This active form of forgetting lacks a satisfactory functional explanation. We investigated optimal decision making for an agent adapting to a stochastic environment where a stimulus may switch between being indicative of reward or punishment. Like Drosophila, an optimal agent shows forgetting with a rate that is linked to the time scale of changes in the environment. Moreover, to reduce the odds of missing future reward, an optimal agent may trade the risk of immediate pain for information gain and thus forget faster after aversive conditioning. A simple neuronal network reproduces these features. Our theory shows that forgetting in Drosophila appears as an optimal adaptive behavior in a changing environment. This is in line with the view that forgetting is adaptive rather than a consequence of limitations of the memory system.

Social motility of African trypanosomes is a property of a distinct life-cycle stage that occurs early in tsetse fly transmission

The protozoan pathogen Trypanosoma brucei is transmitted between mammals by tsetse flies. The first compartment colonised by trypanosomes after a blood meal is the fly midgut lumen. Trypanosomes present in the lumen-designated as early procyclic forms-express the stage-specific surface glycoproteins EP and GPEET procyclin. When the trypanosomes establish a mature infection and colonise the ectoperitrophic space, GPEET is down-regulated, and EP becomes the major surface protein of late procyclic forms. A few years ago, it was discovered that procyclic form trypanosomes exhibit social motility (SoMo) when inoculated on a semi-solid surface. We demonstrate that SoMo is a feature of early procyclic forms, and that late procyclic forms are invariably SoMo-negative. In addition, we show that, apart from GPEET, other markers are differentially expressed in these two life-cycle stages, both in culture and in tsetse flies, indicating that they have different biological properties and should be considered distinct stages of the life cycle. Differentially expressed genes include two closely related adenylate cyclases, both hexokinases and calflagins. These findings link the phenomenon of SoMo in vitro to the parasite forms found during the first 4-7 days of a midgut infection. We postulate that ordered group movement on plates reflects the migration of parasites from the midgut lumen into the ectoperitrophic space within the tsetse fly. Moreover, the process can be uncoupled from colonisation of the salivary glands. Although they are the major surface proteins of procyclic forms, EP and GPEET are not essential for SoMo, nor, as shown previously, are they required for near normal colonisation of the fly midgut.

Comet 1P/Halley multifluid MHD model for the Giotto fly-by

The interaction of comets with the solar wind has been the focus of many studies including numerical modeling. We compare the results of our multifluid MHD simulation of comet 1P/Halley to data obtained during the flyby of the European Space Agency's Giotto spacecraft in 1986. The model solves the full set of MHD equations for the individual fluids representing the solar wind protons, the cometary light and heavy ions, and the electrons. The mass loading, charge-exchange, dissociative ion-electron recombination, and collisional interactions between the fluids are taken into account. The computational domain spans over several million kilometers, and the close vicinity of the comet is resolved to the details of the magnetic cavity. The model is validated by comparison to the corresponding Giotto observations obtained by the Ion Mass Spectrometer, the Neutral Mass Spectrometer, the Giotto magnetometer experiment, and the Johnstone Plasma Analyzer instrument. The model shows the formation of the bow shock, the ion pile-up, and the diamagnetic cavity and is able to reproduce the observed temperature differences between the pick-up ion populations and the solar wind protons. We give an overview of the global interaction of the comet with the solar wind and then show the effects of the Lorentz force interaction between the different plasma populations.

DEVELOPMENT AND APPLICATION OF SHORT-TERM MUTAGENICITY AND CYTOTOXICITY BIOASSAYS FOR INTEGRATED HEALTH ASSESSMENT STUDIES OF COAL FLY ASH EMISSIONS

Two respirable coal fly ash samples ((LESSTHEQ) 3(mu)m), one from a pressurized fluidized-bed combustion miniplant and one from a conventional combustion power plant, were investigated for physical properties, chemical composition and biological activity. Electron microscopy illustrated irregularity in fluidized-bed combustion fly ash and sphericity in conventional combustion fly ash. Elemental analysis of these samples showed differences in trace elements. Both fly ash samples were toxic in rabbit alveolar macrophage and Chinese hamster ovary cell systems in vitro. The macrophages were more sensitive to toxicity of fly ash than the ovary cells. For measuring the cytotoxicity of fly ash, the most sensitive parameters were adenosine triphosphate in the alveolar macrophage system and viability index in the hamster ovary system. Intact fluidized-bed combustion fly-ash particles showed mutagenicity only in strains TA98 and TA1538 without metabolic activation in the Ames Salmonella assay. No mutagenicity was detected in bioassay of conventional combustion fly ash particles. Solvent extraction yielded more mass from fluidized-bed combustion fly ash than from conventional combustion fly ash. The extracts of fluidized-bed combustion fly ash showed higher mutagenic activity than conventional combustion fly ash. These samples contained direct-acting, frameshift mutagens.^ Fly ash samples collected from the same fluidized-bed source by cyclones, a fabric filter, and a electrostatic precipitator at various temperatures were compared for particle size, toxicity, and mutagenicity. Results demonstrated that the biological activity of coal fly ash were affected by the collection site, device, and temperature.^ Coal fly ash vapor-coated with 1-nitropyrene was developed as a model system to study the bioavailability and recovery of nitroaromatic compounds in fly ash. The effects of vapor deposition on toxicity and mutagenicity of fly ash were examined. The nitropyrene coating did not significantly alter the ash's cytotoxicity. Nitropyrene was bioavailable in the biological media, and a significant percentage was not recovered after the coated fly ash was cultured with alveolar macrophages. 1-Nitropyrene loss increased as the number of macrophages was increased, suggesting that the macrophages are capable of metabolizing or binding 1-nitropyrene present in coal fly ash. ^