Dissertations / Theses: 'Lava Dome'

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Holland, Alastair Simon Peter. "Degassing processes at Santiaguito lava dome, Guatemala." Thesis, University of Bristol, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.558078.

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This thesis focuses on using spectroscopic gas emissions data to understand degassing processes occurring during low-intensity explosive activity at Santiaguito lava dome, Guatemala. It results in a refinement of the ultra violet camera spectroscopic technique; the proposal of a trigger mechanism for low-intensity explosions during lava dome growth; and the first successful modelling of an unsteady explosion plume. The ultra violet camera provides high spatial and temporal resolution spectroscopic measurements of volcanic 802, However, data collection is difficult under the non-ideal conditions typically encountered at silicic volcanoes. A new processing protocol is developed that corrects for plume-instrument distance and in-plume ash/aerosols, permitting data collection at 8antiaguito. The resulting dataset is used to constrain the trigger mechanism of 8antiaguito explosions. The lava dome is found to be continuously permeable, whilst explosions contain as little as 150 kg 802 - characteristics incompatible with gas pressurisation beneath an impermeable plug. Rather, the data support a model in which transient explosive degassing pathways are generated at the conduit margins through shear-driven fracturing. Rheological modelling shows that this process is likely to occur during even extremely slow extrusion of high-crystallinity intermediate magma, on account of the very high viscosity of such magma. This model is further supported by the discovery of tuffisite veins in Santiaguito dacite. Santiaguito explosions form short-duration plumes that may be used as observable proxies for larger Vulcanian plumes. Ultra violet camera data have been used to define time-varying boundary conditions for a cutting-edge unsteady plume model. This represents a first attempt to compare field observations of a volcanic plume with model predictions using field-derived boundary conditions. The resulting simulation closely recreates the observed plume ascent, in contrast to approximations made using steady and instantaneous plume models. This explicitly shows that unsteady effects are critical to understanding Vulcanian plume dynamics.

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Ball, Jessica Lynne. "Field and numerical investigations of lava dome hydrothermal systems and their effects on dome stability." Thesis, State University of New York at Buffalo, 2014. http://pqdtopen.proquest.com/#viewpdf?dispub=3612916.

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This study investigates the potential for hydrothermal alteration and circulation in lava domes using combined analytical, remote sensing and numerical modeling approaches. This has been accomplished in three parts: 1) A comprehensive field, geochemical and remote sensing investigation was undertaken of the hydrothermal system in the Santiaguito lava dome complex in Guatemala. The Santiaguito domes were found to contain mainly hydrous silica alteration, which is unlikely to weaken dome rock, but the summit of Santa Maria was found to contain pervasive argillic alteration (clay minerals), which do pose more of a collapse-related hazard. These results were confirmed by hot spring geochemistry which indicated that water in the domes was responsible for some rock dissolution but had a residence time too short to allow for secondary mineralization. 2) A finite element numerical modeling approach was developed which was designed to simulate the percolation of meteoric water in two dome geometries (crater-confined and 'perched'), and the results were compared to the surface expression of hydrothermal systems on existing lava domes. In both cases, we concluded that simulated domes which lacked a high-temperature (magmatic) heat source could not develop a convecting hydrothermal system and were dominated by gravitational water flow. In these low-temperature simulations, warm springs (warmer high fluid fluxes) were produced at the base of the dome talus and cool springs were dispersed lower down the slope/substrate; fumaroles (high vapor fluxes) were confined to the dome summits. Comparison with existing dome cross sections indicates that the simulations were accurate in predicting fumarole locations and somewhat accurate at predicting spring locations, suggesting that springs may be subject to permeability contrasts created by more complicated structural features than were simulated in this study. 3) The results of the numerical modeling were used to calculate alteration potential in the simulated domes, indicating the most likely areas where alteration processes might either reduce the strength of a dome or reduce permeability that could contribute to internal pressurization. Rock alteration potential in low-temperature lava domes was found to be controlled by material permeability and the presence or absence of a sustained heat source driving hydrothermal circulation. High RAI values were preserved longer in low-permeability domes, but were more strongly developed in domes with higher permeabilities. Potential for mineral dissolution was highest at the base of the dome core, while the potential for mineral precipitation is highest at the dome core-talus interface. If precipitated minerals are impermeable, the dome core/talus interface would be a likely location for accumulation of gases and initiation of gas-pressurization-related collapse; if alteration is depositing weak (i.e. clay) minerals in this area, the dome core/talus interface might be a candidate for collapses occurring as the result of alteration processes.

The results of this study are all geared toward answering two broad questions: Where are hydrothermal alteration processes likely to occur or be focused within lava domes? and What effect could these processes have on dome stability? In the specific case of the Santiaguito dome complex, the combination of a quickly-recharged, low-temperature hydrothermal system in the inactive domes actually indicated a low possibility of collapse related to alteration minerals. This result was reinforced by the results of the numerical modeling, which indicated that domes are unlikely to develop sustained hydrothermal convection without the presence of a significant (magmatic) heat source and—in the case of Santiaguito—are likely to produce more hydrous silica alteration minerals when they also lack a source of acidic gases. Models of alteration potential do detail, however, that both shallow and deep dome collapses are still a possibility with a low-temperature hydrothermal system, given either a) a source of acidic gases to drive the formation of clay minerals (which are most likely to be deposited at the core/talus interface of a dome, or b) enough deposition of silica minerals in pore spaces to lower permeability in dome rock and promote internal gas pressurization. The results of this study are not limited to lava domes, as the volcanic edifices on which they rest are composed of the same materials that comprise lava domes and are therefore susceptible to the same hydrothermal processes. Further simulations of both lava domes and their associated edifices, including mineral species models, could help constrain under what conditions a lava dome or volcano is likely to develop areas of weak mineral precipitates (such as clay minerals) which could provide sites for collapse, or develop an impermeable cap of silicate minerals which could trap rising vapor and contribute to the pressurization of the edifice in question (which can in turn lead to collapse).

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Hale, Alina Jane. "Computationally Modelling the Lava Dome at Soufriere Hills Volcano, Montserrat." Thesis, University of Reading, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.485361.

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Finite element method (FEM) models using the commercially available software package FASTFLO and traditional low-level computational programming methods have been used to consider the Peleean lava dome extruded on Soufriere Hills Volcano, Montserrat. Phenomenological nonNewtonian models are used to describe the complex rheology of the lava and time-dependent processes. Four research areas are studied: endogenous dome growth, the transition from endogenous to exogenous dome growth, conduit flow dynamics and the stability of structures containing lava domes. An elasto-viscoplastic FEM model is used to analyse the rheological gradients and the growth and evolution of an endogenous lava dome. The transition from endogenous to exogenous dome growth is an important process in Peleean lava domes. It is found that the development of shear planes within the conduit and lava dome ultimately govern this process and that the lava must be non-Newtonian for shear planes to form. Temporal non-linearities observed in the extrusion rate for Soufriere Hills Volcano are analysed in conduit flow models. Accelerating extrusion rates can be explained by a change in magma chamber over-pressure and a 'rheological memory' associated with the magma. Non-Newtonian magma may form unstable shear planes due to gas over-pressure in the conduit and it is thought that this process is responsible for hybrid seismicity and oscillatory flow. Model results show a first order fit to the cyclicity behaviour observed. The graZritational instability of lava domes may be influenced by viscous relaxation. Instability models show a possible time-delayed collapse mechanism as well as enhanced front lobe toppling. Numerical models are only as useful as the data used to constrain them and due to a paucity of data these models should be regarded as qualitative rather than quantitative.

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Lamb, O. D. "Monitoring lava dome eruptions : a seismic, acoustic and experimental study." Thesis, University of Liverpool, 2017. http://livrepository.liverpool.ac.uk/3008537/.

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Lava dome eruptions are one of the most dangerous forms of volcanic activity. Geophysical, experimental, field or numerical investigations over the past few decades have improved our understanding of dynamic processes associated with these eruptions. In this thesis, I use multi-disciplinary approaches to analyse unrest at four different volcanoes: Volcán de Colima, Unzen, Santiaguito dome complex and Mt. Redoubt. At Volcán de Colima, waveform correlation and seismic interferometry techniques are used to analyse seismic data collected prior to the November 1998 eruption. A decrease in seismic velocity is observed during pre-eruptive activity, consistent with rock failure caused by increased stress associated with the migration of magma towards the surface. This mechanism is confirmed by measurements during experimental Brazil tests on lava samples from the volcano. Furthermore, repetitive micro-cracking during the experiments suggest some repeating earthquakes detected at Volcán de Colima were produced by repeated tensile failure. At Unzen, I analyse seismic data collected during the formation of a lava spine during the last phase of the 1991-95 eruption. Two large groups of repeating earthquakes are identified and further analysis demonstrates how their sources migrated during their period of activation. Citing experimental and field observations, repeated slip motion along the margins of the spine are inferred as the source mechanisms for these earthquakes. Santiaguito dome complex is one of the most active volcanoes in the world, and here I present the first long-term seismo-acoustic dataset to be recorded at the volcano. The dataset captures a major transition in explosive activity that took place in 2015. Variations in energies and waveform arrival times are used to gain insights into the explosion source dynamics. During its eruption in 2009, Mt. Redoubt volcano erupted 19 times, at least 16 of which produced ash plumes tall enough to disrupt air traffic in the region. Using infrasound data recorded during two of these explosions and a three-dimensional plume rise model, I demonstrate how it is possible to efficiently and accurately estimate the ash plume height soon after an eruption begins. These four case studies demonstrate how using a combination of geophysical, experimental, numerical, and field observations can provide more robust interpretations of dynamic processes prior to or during lava dome eruptions. Therefore, multi-disciplinary approaches to studying volcanic activity can have important implications for hazard assessments at active volcanoes worldwide.

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Hornby, A. J. "Fracture, friction and fragmentation : brittle processes at lava dome volcanoes." Thesis, University of Liverpool, 2016. http://livrepository.liverpool.ac.uk/3005862/.

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The extent to which transitions from dominantly viscous to dominantly brittle magma deformation regulate eruptive activity has not been widely explored in volcanology. Within this thesis, investigations combining experiments, petrology and geophysical signals are presented to help decipher and understand the role of brittle deformation during lava dome eruptions. Lava domes are commonly associated with explosions and dome collapse events, both of which generate volcanic ash. In order to recognise and discriminate fragmentation mechanisms from ash samples, the physical properties and mineralogy of natural ash produced during a typical Vulcanian explosion and a dome collapse event were compared. Measurements of the componentry of several thousand ash particles were conducted using QEMSCAN® Particle Mineralogical Analysis, a rapid automated SEM-EDS mapping technique. Analysis of images obtained by QEMSCAN® reveals that the relative distribution of plagioclase and glass present along the ash particle boundaries varied for both generation mechanisms. Deconvolution of particle size distributions and particle shape analyses shows that ash ejected in Vulcanian explosions has a more complex fragmentation and transport history, while ash produced in pyroclastic flows shows the dominance of a single process. These results suggest mechanism-dependent controls on the surface composition and componentry of volcanic ash – future work is required to discriminate fragmentation mechanisms from ash characteristics through the use of QEMSCAN® data. Explosive fragmentation at lava dome volcanoes is likely to be triggered by tensile failure of magma following stress accumulation. In order to investigate pressure-driven fracturing of conduit magma, Brazilian tensile tests were conducted on lava samples from Santiaguito volcano at ambient and magmatic temperatures. These tests reveal that deformation style becomes sensitive to small changes in temperature and strain rate at temperatures of 750-800 °C. Higher temperatures generated increasingly viscous deformation, while faster strain rates promoted more brittle behaviour. Experimental constraints on the strain rate and strain leading to failure can be compared to natural deformation timescales recorded in cycles of inflation preceding explosions at Santiaguito, which shows that a viscous component accompanies deformation and suggests that fractures propagate away from a pressure source prior to explosive eruption. Following fracture propagation, any remaining energy is likely to be accommodated by fault slip along the fracture plane. These faulting events are investigated using a high-velocity rotary shear apparatus, showing that the response to faulting generates temperatures sufficient to produce frictional melt within ~10 cm of slip under the slip rates and normal stresses constrained through monitoring of the volcanic behaviour at Santiaguito. The range of mechanical response to slip events in the volcanic conduit and their relation to concurrent seismic signals are investigated in greater detail during the extrusion of a lava spine at Mt Unzen (Japan). Examination of textures at the spine margins and similarity of the seismic signals that accompanied its extrusion has determined that spine emplacement proceeds by incremental fault slip events in the shallow edifice. Waveform analysis together with spine growth observations allow calculation of the average slip distance (8.9 cm) and slip velocity (0.75 m.s-1). These calculations are combined with results from laboratory measurements in a high-velocity rotary shear apparatus to define the range of depths where average faulting events would induce viscous remobilisation (at >275m) and frictional melting along the fault plane (at >500 m). The frictional properties of the dome rocks and the viscosity of the frictional melt in the fault zone suggest that at shallow depths frictional melts act as a viscous brake to fault slip, potentially augmenting stick-slip spine growth. Taken together, the failure, faulting and fragmentation of dome-forming magma demonstrates that our interpretation of eruptive activity at lava dome volcanoes requires a fundamental understanding of brittle processes.

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Scott, Jeannie A. J. "Origin and evolution of the Santiaguito lava dome complex, Guatemala." Thesis, University of Oxford, 2013. http://ora.ox.ac.uk/objects/uuid:d6e6be78-4464-4b6d-b236-46e22ff8826d.

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Subduction zone volcanoes are a major natural hazard, frequently endangering lives and livelihoods. The eruptive history of many subduction zone volcanoes includes the extrusion of blocky, silicic lava that forms domes or flows, but we do not yet understand what determines the duration of dome-forming behaviour, what path magma may take to the surface, or how these systems may change over time. This thesis presents an investigation of the Santiaguito complex of lava domes and flows in Guatemala, which has been erupting continuously since its inception in 1922. The Santiaguito lavas are predominantly dacitic to andesitic, with a gradual reduction in SiO2 content from ~66 wt% in the 1920s, to ~62 wt% in 2002. This is consistent with a ~15% decrease in the extent of fractional crystallization over that time. The compositions of plagioclase phenocryst cores indicate a diminished role for magma mixing after the 1940s. I model the Santiaguito system as progressively extracting magma from an extensive, chemically-stratified storage zone. Petrological data are consistent with a storage zone extending from ~25 to ~12 km depth, and magma storage temperatures of ~940 to ~980°C. Phenocryst-hosted apatites suggest melt in this storage zone contained 401 to 1199 ppm S, 600 to 1300 ppm F, and 4100 to 6200 ppm Cl. Ascending magma may pass slowly through a conduit bottleneck, or plug, at shallow depths; groundmass texture suggests that melt rigidifies at or near the base this plug. Pre-eruptive melt volatile concentrations suggest time-averaged fluxes of 40 to 263 Mg d-1 SO2, 32 to 145 Mg d-1 HF, and 247 to 708 Mg d-1 HCl, giving ratios of 0.6 to 0.8 HF/SO2, and 2.7 to 6.2 HCl/SO2. These results are consistent with the few direct measurements of SO2 at Santiaguito, and with measured halogen emissions from other silicic dome-forming systems.

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Kingsbury, Cole G. "Physical Volcanology of Obsidian Dome, California: A Complex Record of Emplacement of a Youthful Lava Dome." Thèse, Université d'Ottawa / University of Ottawa, 2012. http://hdl.handle.net/10393/22840.

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Obsidian Dome is a 550-650 year old, 1.5 by 1.8 km extrusion of high silica rhyolite situated along the Inyo Craters in eastern California. Field, and observations of drill core, reveals discrete metre-scale thick zones of rhyolitic glass exposed along the margin of Obsidian Dome as well as within its interior. Millimetre-scale flow-banded obsidian, pumice and rhyolite range from planar to chaotically folded, the latter a product of ductile, compressive deformation. Fractures, some of which display en-echelon splitting patterns are a result of brittle failure. Taken together, these features along with others, result from flow during lava dome growth and suggest complex emplacement patterns signified by vesiculation, crystallization and repeated brittle-ductile deformation, owing to episodic crossing of the glass transition. Evidence further shows that gas loss from the system occurred due to explosions, pumice formation and also brecciation of the melt as it episodically crossed the glass transition. Loss of gas by these mechanisms along with the inherent high viscosity of rhyolite melt explains the large amount of glass found on and within Obsidian Dome and other similar rhyolite extrusions in comparison to less silica-rich systems.

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Ashwell, Paul. "Controls on rhyolite lava dome eruptions in the Taupo Volcanic Zone." Thesis, University of Canterbury. Geological Sciences, 2014. http://hdl.handle.net/10092/8965.

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The evolution of rhyolitic lava from effusion to cessation of activity is poorly understood. Recent lava dome eruptions at Unzen, Colima, Chaiten and Soufrière Hills have vastly increased our knowledge on the changes in behaviour of active domes. However, in ancient domes, little knowledge of the evolution of individual extrusion events exists. Instead, internal structures and facies variations can be used to assess the mechanisms of eruption. Rhyolitic magma rising in a conduit vesiculates and undergoes shear, such that lava erupting at the surface will be a mix of glass and sheared vesicles that form a permeable network, and with or without phenocryst or microlites. This foam will undergo compression from overburden in the shallow conduit and lava dome, forcing the vesicles to close and affecting the permeable network. High temperature, uniaxial compression experiments on crystal-rich and crystal-poor lavas have quantified the evolution of porosity and permeability in such environments. The deformation mechanisms involved in uniaxial deformation are viscous deformation and cracking. Crack production is controlled by strain rate and crystallinity, as strain is localised in crystals in crystal rich lavas. In crystal poor lavas, high strain rates result in long cracks that drastically increase permeability at low strain. Numerous and small cracks in crystal rich lavas allow the permeable network to remain open (although at a lower permeability than undeformed samples) while the porosity decreases. Flow bands result from shear movement within the conduit. Upon extrusion, these bands will become modified from movement of lava, and can therefore be used to reconstruct styles of eruption. Both Ngongotaha and Ruawahia domes, from Rotorua caldera and Okataina caldera complex (OCC) respectively, show complex flow banding that can be traced to elongated or aligned vents. The northernmost lobe at Ngongotaha exhibits a fan-like distribution of flow bands that are interpreted as resulting from an initial lava flow from a N – S trending fissure. This flow then transitioned into intrusion of obsidian sheets directly above the conduit, bound by wide breccia zones which show vertical movement of the sheets. Progressive intrusions then forced the sheets laterally, forming a sequence of sheets and breccia zones. At Ruawahia, the flow bands show two types of eruption; long flow lobes with ramp structures, and smaller spiny lobes which show vertical movement and possible spine extrusion. The difference is likely due to palaeotopography, as a large pyroclastic cone would have confined the small domes, while the flow lobes were unconfined and able to flow down slope. The vents at Ruawahia are aligned in a NE – SW orientation. Both domes are suggested to have formed from the intrusion of a dyke. The orientations of the alignment or elongation of vents at Ngongotaha and Ruawahia can be attributed to the overall regional structure of the Taupo Volcanic Zone (TVZ). At Ngongotaha, the N – S trending elongated vent is suggested to be controlled by a N – S trending caldera collapse structure at Rotorua caldera. The rest of the lobes at Ngongotaha, as well as other domes at Rotorua caldera, are controlled by the NE – SW trending extensional regional structure or a NW – SE trending basement structure. The collapse of Rotorua caldera, and geometry of the deformation margin, are related to the interplay of these structures. At Ruawahia, the NE – SW trending vent zone is parallel to the regional extension across the OCC, as shown by the orientation of intrusion of the 1886AD dyke through the Tarawera dome complex. The NE – SW trending regional structures observed at both Rotorua caldera and Okataina caldera complex are very similar to each other, but differ from extension within the Taupo rift to the south. Lava domes, such as Ngongotaha, that are controlled by this structure show that the ‘kink’ in the extension across Okataina caldera complex was active across Rotorua caldera during the collapse at 240 ka, and possibly earlier. This study shows the evolution of dyke-fed lava domes during eruption, and the control of regional structures in the location and timing of eruption. These findings improve our knowledge of the evolution of porosity and permeability in a compacting lava dome, as well as of the structures of Rotorua caldera, the longevity of volcanic activity at dormant calderas and the hazard potential of dyke-fed lava domes.

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Friedlander, Elizabeth Anne. "The nature and evolution of conduit faults in the 2004-2008 Mount St. Helens lava dome eruption." Thesis, University of British Columbia, 2012. http://hdl.handle.net/2429/40473.

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Mount St. Helens reawakened 24 years after erupting in the 1980’s. This effusive eruption produced 95 million cubic meters of dacite in the form of 7 discrete, competent spines or domes of lava between September 2004- June 2008. The spines comprise low-porosity dacite that is inferred to have crystallized at a depth of about 1 km and are enveloped by a 1-3 meter carapace of fault gouge. The rate of linear extrusion of the spines peaked at 11 m/day in November 2004 and subsequently slowed to < 0.5 m/day. Dome growth was accompanied by a “drumbeat” seismicity that was sourced from 1-0.5 km below the vent. Here, field, petrographic, and microstructural observations on the nature of deformation attending the extrusion of Spines 4, 5 and 7 at Mount St. Helens (2004-2006) are presented. The enveloping fault zones provide a static view of the cumulative strain produced by shear along the conduit wall. The conduit faults narrow from Spine 4 to Spine 7 and exhibit fewer macroscopic brittle features. Strain accommodation is achieved through a scale-dependent ductility. The subsurface ascent velocities for each packet of magma are reconstructed using surface observed extrusion rates. Computed shear strain rates for the margins of the conduit range from 1x10⁻⁴ to 7.9x10⁻⁵ s⁻¹. As ascent rate decreases, fault zone width also decreases maintaining an average shear strain rate of 4.3x10⁻⁵ s⁻¹. Intense strain localization within each fault zone is expressed by 0.001 m thick slickensides implying very high (co-seismic) transient shear-strain rates of 1x10⁻¹s⁻¹ (Spines 4-5) to 2.2x10⁻²s⁻¹ (Spine 7). I conclude with a time and space model for the evolution of the fault zone as magma ascends the conduit, and how the fault zones evolve through time. The factors that contribute to the differences in conduit fault zone width and nature throughout the eruption are: 1) differences in ascent rates at the onset and origin of brittle failure, 2) variations in shear strain rates, 3) and the increasing residence time throughout the eruption that the damaged fault rocks experienced at high temperatures within the conduit.

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Zorn, Edgar Ulrich Verfasser], Thomas [Akademischer Betreuer] Walter, and Ulrich [Gutachter] [Küppers. "Monitoring lava dome growth and deformation with photogrammetric methods and modelling / Edgar Ulrich Zorn ; Gutachter: Ulrich Küppers ; Betreuer: Thomas Walter." Potsdam : Universität Potsdam, 2020. http://d-nb.info/1223022455/34.

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Hicks, Peter Daniel. "A thermodynamic model of rainwater and magmatic vapour flow in a porous medium : triggering of a volcanic lava dome collapse." Thesis, University of East Anglia, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.445213.

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Zorn, Edgar Ulrich [Verfasser], Thomas Akademischer Betreuer] Walter, and Ulrich [Gutachter] [Küppers. "Monitoring lava dome growth and deformation with photogrammetric methods and modelling / Edgar Ulrich Zorn ; Gutachter: Ulrich Küppers ; Betreuer: Thomas Walter." Potsdam : Universität Potsdam, 2020. http://d-nb.info/1223022455/34.

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Yamasato, Hitoshi. "Study on infrasonic waves associated with growth and collapse of dacitic lava dome and pyroclastic flow at Unzen volcano, Japan." 京都大学 (Kyoto University), 1998. http://hdl.handle.net/2433/182452.

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Gaunt, H. E. "Experimental study of permeability under simulated volcanic conditions on lava dome rocks from Mount St. Helens : constraints on degassing and eruption style." Thesis, University College London (University of London), 2014. http://discovery.ucl.ac.uk/1426442/.

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The research presented in this thesis integrates field observations and sampling, data from controlled laboratory experiments with a radially-symmetric fluid flux model to investigate permeability controls on degassing processes operating during lava dome eruptions at silicic volcanoes. Laboratory permeability measurements were made on samples collected systematically across the marginal shear zone of a lava spine at Mount Saint Helens (MSH), Washington, USA, from the 2004-08 eruption, at room temperature and confining pressures up to 85 MPa. Permeability experiments were also performed on samples of massive dacite from the spine core at a range of temperatures up to 900°C and a confining pressure of 10 MPa. A simplified radially-symmetric fluid flux model was developed which incorporated the observed structure of the conduit at Mount Saint Helens and the measured permeability profile to show the effects of the permeability on the magnitude and direction of fluid flow. Permeability was found to be essentially isotropic in the conduit interior but highly anisotropic in the marginal shear zone rocks. Vertical permeability in the marginal rocks is increased by two orders of magnitude, through the formation of an aligned shear fracture network. Ultracataclasite shear bands in the fault core also decreased the horizontal permeability by two orders of magnitude. Permeability was also seen to decrease by around four orders of magnitude as temperature was increased to 900°C. In contrast to previous work that assumed significant lateral transport of gases, modeled fluid flow using the experimentally determined permeability data shows that the vertical volatile volumetric flow rate will be orders of magnitude greater than the horizontal rate into the wall rock; more than 90% of volatile flow would have been partitioned vertically within the conduit-margin fault zone, consistent with the location of gas and ash venting during the eruption. Changes in permeability with temperature indicate that magma rising in the conduit becomes progressively more permeable to gas escape during ascent and crystallisation. When applied to gas sealing processes, the intrusion of molten lava under a solidified plug and the associated heating may cause the permeability of the overlying rock to decrease sufficiently that gas escape is inhibited, allowing for the build up of pressure and potentially an explosive eruption.

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Portal, Angélie. "Etude géophysique de la structure interne d'un dôme volcanique : le Puy de Dôme et son environnement (Chaîne des Puys, France)." Thesis, Clermont-Ferrand 2, 2015. http://www.theses.fr/2015CLF22647/document.

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Les dômes de lave sont associés à des éruptions volcaniques violentes et des indices d’explosivité élevés. L’observation et la surveillance de dômes actifs (e.g. St. Helens, Unzen, Montserrat) ont mis en évidence des modes de croissance caractérisés par des phases d’extrusion, d’explosion et des phénomènes d’effondrement, impliquant une structure interne souvent complexe de ces édifices volcaniques. L’étude du Puy de Dôme (Massif Central français), un dôme trachytique âgé de 11 000 ans, grâce à l’apport de l’imagerie géophysique et à la modélisation des données, ainsi qu’à une analyse morpho-structurale détaillée, a permis d’établir un modèle précis de la structure interne du dôme et a fourni de nouvelles contraintes concernant sa croissance et son évolution. L’analyse du Modèle Numérique de Terrain haute résolution (0,5 m) a permis d’identifier différentes unités sur le dôme, morphologiquement distinctes, et associées à des dynamismes éruptifs différents, ainsi que des structures volcano-tectoniques remarquables sur les édifices volcaniques voisins (Petit Puy de Dôme et Puy des Grosmanaux). Différentes méthodes géophysiques (tomographie des résistivités électriques – ERT -, gravimétrie et magnétisme) ont été mises en oeuvre afin d’étudier la structure interne du dôme, et de caractériser la nature des mécanismes à l’origine des zones de déformations identifiées dans l’environnement du Puy de Dôme. L’utilisation de plusieurs méthodes a permis d’étudier des paramètres physiques différents mais complémentaires, bien que l’interprétation globale des résultats géophysiques ait parfois été délicate dans le cas d’un édifice volcanique aussi complexe. Les modèles géophysiques 2D et 3D obtenus montrent que le Puy de Dôme repose sur des édifices volcaniques préexistants, un ensemble de volcans stromboliens dont la présence et/ou l’extension exacte étaient partiellement méconnues jusqu’alors. La structure interne de l’édifice, très hétérogène, est constituée d’une partie centrale très massive, entourée d’une ceinture de brèches d’effondrement, la zone sommitale du conduit étant affectée de nombreuses évidences d’une forte altération hydrothermale, caractéristique des dômes volcaniques. La partie supérieure du dôme est définie par une carapace de roches consolidées, de quelques dizaines de mètres d’épaisseur au maximum, alors que la base de l’édifice forme un talus constitué des dépôts d’effondrements gravitaires et d’écoulements pyroclastiques associés à la croissance du dôme. Enfin, les données gravimétriques et magnétiques ont permis la mise en évidence de la présence d’intrusions sous les édifices du Petit Puy de Dôme et du Puy des Grosmanaux. La géométrie de ces intrusions, déterminées grâce à différentes approches de modélisation, ainsi que la nature des roches qui les composent indiquent des processus de mise en place complexes
Volcanic domes are associated to violent volcanic eruptions and high explosivity indexes. Observation and monitoring of active domes (e.g. St. Helens, Unzen, Montserrat) underlined growth patterns characterized by extrusion phases, explosions and collapse events, involving the complex inner structure of these volcanic edifices. The study of the Puy de Dôme volcano (French Massif Central), a 11,000 years old trachytic lava dome, through geophysical imaging and data modelling, as well as a detailed morpho-structural analysis, allowed to build a precise model of the inner structure of the dome and provided new constraints about its growth and its evolution. The analysis of the high resolution Digital Terrain Model (0.5 m) allowed to identify distinct morphological units on the dome, as well as volcano-tectonic structures on the neighboring volcanic edifices (Petit Puy de Dôme and Puy des Grosmanaux). Different geophysical methods (Electrical Resistivity Tomography – ERT -, gravity and magnetism) have been implemented in order to study the inner structure of the dome and to characterize the initiating mechanisms of the deformations areas identified in the Puy de Dôme vicinity. The use of several methods allowed to study different, but complementary physical parameters, although the overall interpretation of the geophysical results is sometimes difficult in the case of a volcanic edifice so complex. The 2D and 3D geophysical models obtained indicate that the Puy de Dôme is based on preexisting volcanic edifices, a cluster of strombolian volcanoes whose the presence and/or the exact extension were partially unknown until now. The internal structure of the edifice, highly heterogeneous, is composed of a massive central part, encompassed of collapse breccia, and its summit part highlights evidences of a strong hydrothermal alteration, characteristic feature of volcanic domes. The upper part of the dome is defined by a carapace of consolidated rocks, a few meters thick, whereas the base of the edifice forms a talus composed of collapses and pyroclastic flows deposits associated to the dome growth. Finally, gravity and magnetic data pointed out the presence of intrusions beneath the Petit Puy de Dôme and the Puy des Grosmanaux edifices. The geometry of these intrusions, determined through different modelling approaches, and the nature of the rocks that composed them, indicate complex emplacement processes

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Hernandez, Brett M. "Physical Volcanology, Kinematics, Paleomagnetism, and Anisotropy of Magnetic Susceptibility of the Nathrop Volcanics, Colorado." Bowling Green State University / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1400251995.

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Hernández, Prat Loreto Tamara. "Evolución geoquímica del domo cerro La Torta, El Tatio, a través de inclusiones vítreas." Tesis, Universidad de Chile, 2017. http://repositorio.uchile.cl/handle/2250/148433.

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Geóloga
El Cerro La Torta es un domo volcánico riolítico, de 34 ka de edad, ubicado en la zona de El Tatio, al oeste de los Cerros de Tocorpuri, en la frontera con Bolivia, a 1270 km al noreste de Santiago y 100 km al este de Calama. Abarca un área de 12 km2 y un volumen de 4,7 km3 a una altura de 5090 m s.n.m. El objetivo principal de este estudio es reconstruir los procesos ígneos que ocurrieron en evolución del magma que formó el Cerro La Torta mediante inclusiones vítreas. Para esto se realizaron análisis en microsonda electrónica y ablación láser luego de un detallado trabajo de petrografía de inclusiones vítreas hospedadas en anfíbol y plagioclasa. El domo Cerro la Torta erupcionó a partir de un magma riolítico, rico en potasio y con un 74,5% wt de sílice desde una fuente magmática que cristalizó a presiones de entre 114 y 185 MPa, equivalentes a profundidades entre los 90 y 2390 m. bajo el nivel del mar. La temperatura de cristalización de las distintas fases y sus respectivas inclusiones varía entre 949 y 723 °C en promedio. La fugacidad de oxígeno del fundido (logfO2) es -12,3, indicando un ambiente oxidante, y el porcentaje de agua del fundido, 4,9% wt. A pesar de los datos anteriores, las inclusiones estudiadas registran un último evento de cristalización de fases minerales debido a que un magma de 74% de sílice no puede fraccionar piroxeno, por lo que la fuente real está más profunda y menos diferencia. La gran presencia de andesina indica que este magma parental real, es andesítico. Se establecen dos modelos de fuente magmática para La Torta. i) Fuente magmática más profunda que los 2,6 km de espesor, que en un principio (0,8 Ma) tenía composición andesítica a dacítica, erupcionando el volcán Tocorpuri y, posteriormente, los Cerros de Tocorpuri. ii) Fuente magmática netamente riolítica alimentada por otra más profunda y primitiva. Este magma contenía enstatita y magnesio-hornblenda que por un calentamiento provocado por otro cuerpo magmático más primitivo se disolvieron violentamente, enriqueciendo el sistema en Ni, Cr y tierras raras pesadas, quedando escasos micro-fenocristales de enstatita. Las nuevas fases de Mg.-Hbl asimilaron estos elementos tanto en su cristal como en sus inclusiones. Posteriormente, el magma fue ascendiendo y cristalizando fraccionadamente a fases minerales como cuarzo y biotita, registrando un decaimiento en la concentración de los elementos compatibles de las inclusiones de centro a borde. Luego de un periodo de residencia suficiente para formar fenocristales de hasta un cm de largo, ocurre una descompresión y recalentamiento debido a la fuente de calor aportada por el APMB, que creó las texturas de reabsorción en cuarzo y anfíbol.
22/12/2019

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Rech, Karine Cristiane. "Desenvolvimento da criação de larvas de Chironomus sp. (Diptera) e Branchiura sowerbyi (Annelida) para alimentação de peixes de água doce." Florianópolis, 2011. http://repositorio.ufsc.br/xmlui/handle/123456789/95023.

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Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Ciências Agrárias, Programa de Pós-Graduação em Aquicultura, Florianópolis, 2011
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O presente trabalho tem por objetivo desenvolver métodos para a criação de larvas de Chironomus sp. (Diptera) e Branchiura sowerbyi (Annelida). Para o estabelecimento dos métodos, os organismos foram capturados em ambiente natural e transportados para o laboratório, onde diferentes condições foram testadas para avaliação do seu crescimento. Para Chironomus sp. foram testadas a temperatura, o tipo de sedimento e o tipo e o nível de alimentação, sendo que ao final do experimento foram determinadas a sobrevivência e a biomassa. Para Branchiura sowerbyi a influência da densidade e do tipo de alimentação sobre a ovoposição, eclosão de juvenis e sobrevivência dos reprodutores foram analisadas. Os resultados obtidos nos estudos realizados com Chironomus sp. revelaram que as melhores condições para a emergência e reprodução destes organismos ocorreram em sedimentos arenosos e sob temperatura de 25ºC. As larvas apresentaram melhor crescimento e sobrevivência quando alimentadas com ração para peixes ornamentais ou ração para frangos, independentemente do nível de alimentação utilizado. Os estudos com Branchiura sowerbyi mostraram melhor reprodução da espécie em condição de maior densidade e alimentação com ração comercial para frangos, para a qual foi registrada maior ovoposição e produção de jovens. Os resultados deste estudo podem ser usados para o futuro desenvolvimento de métodos de produção em massa dessas espécies para sua utilização como alimento vivo para peixes de água doce.

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Dibacto, Kamwa Stéphane. "Dynamique de construction et démantèlement des volcans tertiaires et quaternaires des Carpates par des approches géomorphologiques et géochronologiques Growth and erosion constraints of the East Carpathians volcanoes by numerical models: tectonic and climatic implications Eruptive history of the Late Quaternary Ciomadul (Csomád) volcano, East Carpathians, part II: magma output rates Eruptive history of the Late Quaternary Ciomadul (Csomád) volcano, East Carpathians I: timing of lava dome activity constrained by the unspiked K-Ar method." Thesis, université Paris-Saclay, 2020. http://www.theses.fr/2020UPASS144.

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Dans cette thèse, 47 nouveaux âges ont été obtenus par la technique Cassignol-Gillot. La très bonne reproductibilité des âges obtenus, ajoutée à une stricte cohérence observée entre les édifices volcaniques, supporte l'utilisation de la méthode K-Ar dans la datation des laves des Carpates orientales (Călimani-Gurghiu-Harghita ; CGH) et des dépôts d'ignimbrite du Miocène des Carpates occidentales (les monts de Mátra et Bükk). Dans la partie orientale de la chaîne, les données géochronologiques ont été combinées avec des analyses géomorphologiques pour contraindre l'histoire volcanique et calculer leur taux de construction et d'érosion. Parallèlement, dans la partie occidentale de la chaîne, les données géochronologiques obtenues ont été combinées aux données paléomagnétiques disponibles pour affiner leur stratigraphie. La chaîne des Carpates orientales a connu une migration de son activité éruptive le long de l’arc du Miocène au Quaternaire. Ici, une méthodologie novatrice et complexe apporte de nouvelles contraintes géochronologiques et géomorphologiques sur l'évolution des 20 volcans de la chaîne. Les nouveaux âges ont permis de contraindre leur durée d’activité Par exemple Seaca-Tătarca (6,79-6,47 Ma), Vârghiş (5,47-4,61 Ma) ou de dater l’activité volcanique la plus récente de Călimani. Pour le complexe volcanique de Ciomadul, composé d'une douzaine de dômes de lave, l’activité volcanique a été contrainte entre 704±18 et 28±1ka (<1 Ma) interrompue de périodes de repos. En parallèle, des reconstructions numériques de paléo-topographies volcaniques ont été réalisées dans le but de quantifier leur forme à la fin de leur construction. Les résultats déduits de nos reconstructions ont donné un volume total de matériel émis de 2300km3 sur toute la chaîne avec, à l’échelle de chaque volcan, une large gamme de variation de leur taille (3±3 à 592±115 km³). Ces volumes montrent une nette diminution du nord au sud de la chaîne avec des valeurs de 910, 880, 279 et 165 km³ pour des secteurs géographiques de Călimani, Gurghiu, North Harghita et South Harghita respectivement. Combinés aux âges, ces volumes ont permis de calculer un taux de construction moyen de 200km³/Ma pour toute la chaîne, représenté par deux groupes distincts ; un groupe caractérisé par des taux de construction de 137 km³/Ma caractéristiques des vieux volcans (11-3,6 Ma) suivi d'un groupe avec des taux de construction de 28km³/Ma pour les volcans Plio-Quaternaires. La comparaison des volcans reconstruits et ceux actuels a permis de calculer un volume érodé total de 524±125km³, correspondant à une dénudation moyenne de 22% et à un taux d'érosion moyen de 20m/Ma pour la chaîne de CGH. Suite aux fluctuations climatiques enregistrées le long de cette chaîne, les taux d'érosion caractéristiques de ces grandes périodes climatiques ont été calculés dans le but de montrer le rôle qu’a joué le climat sur les taux d’érosion. Le taux d'érosion le plus élevé de 38m/Ma a été obtenu pour la période régie par un climat continental subtropical modéré transitionnel (9,5-8,2 Ma). Pour la période climatique continentale modérée (8,2-6,8 Ma), caractérisée par des conditions climatiques beaucoup moins humides, un taux d'érosion de 14 m/Ma est proposé. Pour la période correspondant à un climat continental avec identification de périodes semi-arides (6,8-5,8 Ma), un taux d'érosion de 7 m/Ma a été calculé. Pour les volcans Plio-Quaternaires ayant connus des cycles interglaciaires/glaciaires, un taux d'érosion de 28m/Ma a été obtenu. Une telle approche morphométrique et géochronologique quantitative démontre son efficacité à étudier le dynamisme volcanique, y compris les processus de construction et d'érosion au fil du temps. Dans la partie occidentale des Carpates, les âges obtenus sur les coulées de lave de Börzsöny contraignent sa période d'activité entre 14,3-15,1 Ma. Pour les dépôts ignimbritiques de Bükk, les résultats K-Ar évoluent entre 12,7-16,5 Ma
In this PhD thesis, 47 new ages have been obtained by the Cassignol-Gillot technique. The very good reproducibility of the ages obtained in this study, added to a strict consistency observed between the volcanic edifices, support the use of the K-Ar method in the dating of the East Carpathian lavas (Călimani-Gurghiu-Harghita) and ignimbrite deposits of the North Hungarian (Mátra and Bükk Mts. [western Carpathians]). In the Eastern part, this new geochronological dataset has been combined with geomorphological analyses to constrain the volcanic history as well as to compute construction and erosion rates of those volcanoes. In parallel, in the western part geochronological dataset has been combined with available paleomagnetic data to refine their stratigraphy. The East Carpathian volcanic range experienced an along-arc, Late Miocene to Quaternary migration of eruptive activity. Here, a novel and complex methodology are presented that yields new geochronological and geomorphological constraints on the evolution of the 20 volcanic edifices. New unspiked K-Ar ages either constrain their lifespan (6.79- 6.47 Ma for Seaca-Tătarca; 5.47- 4.61 Ma for Vârghiş) or date the youngest volcanic activity (central Călimani). For Ciomadul volcanic complex composed by a dozen of lava domes, which hosts the recent volcanic activity since the last 1 Ma, its activity has been constrained between 704± 18 ka and 28 ± 1 ka with several quiescence periods. In parallel, numerical reconstructions of volcanic paleo-topographies were performed to quantify their shape at the end of their construction stage. The inferred initial volcano size shows a wide range (3±3 to 592±115 km³), making up the four main successive volcanic segments (910, 880, 279 and 165 km³ for Călimani, Gurghiu,North Harghita and South Harghita segment, respectively) totalizing 2300 km³. Volume and age constraints allowed computing an average growth rate of 200 km³/Ma for the whole range, characterized by an initial moderate growth rate (137 km³/Ma) of the older volcanoes (11-3.6 Ma) followed by a lower growth rate (28 km³/Ma) obtained for the Plio-Quaternary volcanoes. Comparing reconstructed and current topographies yielded a total eroded volume of 524±125 km³, defining averaged denudation of 22% and a 20 m/Ma erosion rate. Erosion rates for major climatic periods were computed, which highlight the contrasting climatic contexts since 11 Ma. The highest erosion rate (38 m/Ma) occurred during a transitional moderate subtropical continental climate period (9.5-8.2 Ma). An intermediate erosion rate (14m/Ma) characterized a moderate continental climate period (8.2-6.8 Ma) when conditions became less humid. The lowest erosion rate (7 m/Ma) reflects the prevailing continental but occasionally semi-arid climate (6.8-5.8 Ma). The highest erosion rate (28m/Ma) was obtained for Plio-Quaternary times during the interglacial/glacial cycles. Such a quantitative morphometric and geochronological approach demonstrates its efficiency to study volcanic dynamism, including both constructional and erosional processes, through time. In the western part of the Carpathian range, the new ages obtained on the lava flows of Börzsöny made it possible to constraint its period of activity between 14.27 - 15.11 Ma. For the Miocene ignimbrite of Bükk foreland, the new K-Ar results range between 12.7 - 16.5 Ma

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Rodrigues, Coralucia Chaltein Bello. "Efeitos da luz solar e cor do tanque no desenvolvimento larval e produção de pos-larvas do camarão Macrobrachium rozenbergii (De Man, 1879)." reponame:Repositório Institucional da UFSC, 1997. http://repositorio.ufsc.br/xmlui/handle/123456789/77071.

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Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Ciencias Agrarias
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Com a finalidade de se avaliar o efeito da luz solar e a cor dos tanques no desenvolvimento larval e produção de pós-larvas do Macrobrachium rozenbergii, foi conduzido um experimento junto ao laboratório de camarão de água doce do Departamento de Aqüicultura-UFSC. Tanto a luz solar quanto a cor dos tanques (preto e branco) não influenciaram na captura e ingestão de alimentos pelas larvas. Os tanques de cor preta produziram mais pós-larvas (P<0.05) e em menor período do que os tanques de cor branca, independente da incidência de luz solar. Os tanques pretos com incidência de luz solar indireta, produziram pós-larvas maiores e mais pesadas (P<0.05) do que os tanques pretos que não recebiam a luz solar. Nos cultivos com tanques brancos, a incidência solar não influenciou no peso e comprimento das pós-larvas (P>0.05). Os resultados nos mostram que o tanque de cor preta são mais indicados e que a incidência de luz solar indireta é um fator que influencia positivamente (P<0.05) no peso e no comprimento das pós-larvas recém metamorfoseadas.

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FREITAS, J. F. N. "Crescimento inicial e eficiência fotoquímica de mangueiras cultivadas em solo contendo lama do rio doce." Universidade Federal do Espírito Santo, 2018. http://repositorio.ufes.br/handle/10/9943.

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RESUMO Este trabalho avaliou os efeitos da lama oriunda do leito do Rio Doce (19º4154550 S, 40º 07 43960 O), sobre a atividade fotossintética e o crescimento de três cultivares enxertadas de Mangífera Indica L. em estádio de muda. O Rio Doce, ao longo dos anos, vem sofrendo com a deposição de materiais contaminados oriundos da extração do minério de ferro. Essa situação agravou-se com o rompimento da barragem de Mariana-MG em novembro de 2015, quando milhões de metros cúbicos de rejeitos de mineração foram depositados e arrastados ao longo da bacia do Rio Doce. Até o momento, pouco se sabe sobre a magnitude do impacto causado pela lama no desenvolvimento das espécies vegetais. A atividade agrícola das regiões próximas ao desastre foi altamente prejudicada, os rejeitos compactaram o solo tornando-o infértil. Entender a fisiologia das plantas submetidas a essa nova realidade ambiental é primordial para as estratégias de recuperação tanto do âmbito ambiental quanto socioeconômico. Para isso, três diferentes cultivares de Mangífera indica L. com destaque no mercado de frutíferas foram utilizadas para avaliar os efeitos dos resíduos de mineração sobre o crescimento e a vitalidade das plantas. Os tratamentos foram caracterizados de acordo com as cultivares (Rosa, Tommy Atkins e Palmer) submetidas a três concentrações dos resíduos de mineração (0%, 20% e 50) presente no substrato a base de turfa. Essas concentrações foram caracterizadas de acordo com as propriedades físicas e químicas. Simultaneamente, as análises nutricionais das folhas das cultivares foram avaliadas. As medidas de crescimento e as análises fotossintéticas foram realizadas mensalmente, entre outubro de 2016 a outubro de 2017. No último mês de análise foi realizada a contagem dos primeiros frutos das cultivares estabelecendo-os em ter categorias de acordo com seu tamanho. Os parâmetros que melhor representaram os efeitos dos resíduos de mineração no desenvolvimento das mudas foram o PITOTAL (Indice de desempenho total da etapa fotoquímica da fotossíntese) e o PIABS (índice de desempenho do FSII). Os danos causados foram evidentes na cv. Rosa, as análises de crescimento, os índices de clorofila, as curvas OJIPs normalizadas juntamente com os parâmetros do teste JIP utilizados, corroboram essa afirmação. Através dessas análises também foi possível observar que as cultivares Tommy Atkins e Palmer não apresentaram redução significativas em resposta ao aumento das concentrações residuais. Os resultados dos macro e micronutrientes foliares revelaram que a cv.Rosa (Tratamento 50%) apresentou níveis tóxicos de Mn, podendo ter contribuído para a severidade do estresse observado. Os resultados indicaram, frente aos efeitos causados pelos resíduos oriundo do leito do Rio Doce, que a cv.Rosa apresentou os mais severos sintomas, resultando em mudas menos desenvolvidas e com uma produtividade inicial reduzida, enquanto as cultivares Tommy Atkins e Palmer demonstraram alta tolerância ao efeitos da contaminação. Palavras-chave: Desastre, fluorescência, crescimento, compactação, mangueira.

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Fragoso, Evelise Nunes. "Ictiofauna da microbacia do Córrego da Lapa, Bacia do Alto Paraná, Itirapina/Ipeúna, SP." Universidade Federal de São Carlos, 2005. https://repositorio.ufscar.br/handle/ufscar/1894.

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Financiadora de Estudos e Projetos
O presente estudo foi desenvolvido na microbacia da Lapa (Itirapina/Ipeúna) localizada na região das Cuestas do centro do estado de São Paulo, com o objetivo de caracterizar a ictiofauna quanto à composição e distribuição logitudinal e vertical a diversidade, riqueza e equitabilidade para cada uma das 12 estações de coleta. Foram amostrados o córrego da Lapa, o córrego Cantagalo e o rio Passa Cinco. (Ver resumo completo em Texto completo para download)

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Rissmann, Clinton Francis. "Using Surface Methods to Understand the Ohaaki Hydrothermal Field, New Zealand." Thesis, University of Canterbury. Geological Sciences, 2010. http://hdl.handle.net/10092/5027.

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After water vapour, CO₂ is the most abundant gas associated with magmatic hydrothermal systems. The detection of anomalous soil temperature gradients, and/or a significant flux of magmatic volatiles, is commonly the only surface signature of an underlying high temperature reservoir. For both heat (as water vapour) and gas to ascend to the surface, structural permeability must exist, as the unmodified bulk permeability of reservoir rock is too low to generate the focussed fluid flow typical of magmatic hydrothermal systems. This thesis reports the investigation into the surface heat and mass flow of the Ohaaki hydrothermal field using detailed surface measurements of CO₂ flux and heat flow. Detailed surface measurements form the basis of geostatistical models that quantify and depict the spatial variability of surface heat and mass flow, across the surface of both major thermal areas, as high resolution pixel plots. These maps, in conjunction with earlier heat and mass flow studies, enable: (i) estimates of the pre-production and current CO₂ emissions and heat flow for the Ohaaki Field; (ii) interpretation of the shallow permeability structures governing fluid flow, and; (iii) the spatial relationships between pressure-induced ground subsidence and permeability. Heat flow and CO₂ flux surveys indicate that at Ohaaki the soil zone is the dominant (≥ 70% and up to 99%) pathway of heat and mass release to the atmosphere from the underlying hydrothermal reservoir. Modelling indicates that although the total surface heat and mass flow at Ohaaki is small, it is highly focused (i.e., high volume per unit area) relative to other fields within the Taupo Volcanic Zone (TVZ). Normalised CO₂ emissions are comparable to other volcanic and hydrothermal fields both regionally and globally. Despite 20 years of production, there is little difference between pre-production and current CO₂ emission rates. However, the similarity of CO₂ emission rates masks a 40% increase in CO₂ emissions from new areas of intense steaming ground that have developed in response to production of the field for electrical energy production. This increase in thermal ground emissions is offset by emission losses associated with the drying up of all steam heated pools and alkali-Cl outflows from the Ohaaki West (OHW) thermal area, in response to production-induced pressure decline. The location of surface thermal areas is governed by the occurrence of buried or partially emergent lava domes, whereas the magnitude of CO₂ flux, mass flow, and heat flow occurring within each thermal area is determined by the proximity of each dome (thermal areas) to major upflow zones. Buried or partially emergent silicic lava domes act as cross-stratal pathways for fluid flow, connecting the underlying reservoir to the surface, and bypassing several hundred metres of the poorly permeable Huka Falls Formation (HFF) caprock. For each dome complex the permeable structures governing fluid flow are varied. At Ohaaki West, thermal activity is controlled by a deep-rooted concentric fracture zone, developed during eruption of the Ohaaki Rhyolite dome. Within the steam-heated Ohaaki East (OHE) thermal area, flow is controlled by a high permeability fault damage zone (Broadlands Fault) developed within the apex of the Broadlands Dacite dome. Structures controlling alkali-Cl fluid flow at OHW also iii appear to control the occurrence and shape of major subsidence bowls (e.g., the Main Ohaaki Subsidence Bowl), the propagation of pressure decline to surface, and the development and localization of pore fluid drainage. Across the remainder of the Ohaaki field low amplitude ground subsidence is controlled by the extent of aquifer and aquitard units that underlie the HFF, and proximity to the margins of the hot water reservoir. The correlation between the extent of low amplitude ground subsidence and the margins of the field reflects the coupled relationship between the hot water reservoir and reservoir pressure. Only where thick vapour-phase zones buffer the vertical propagation of deep-seated pressure decline to the surface (i.e., OHE thermal area), is ground subsidence not correlated with subvertical structural permeability developed within the HFF. This thesis makes contributions to regional and global research on geothermal and hydrothermal systems by: (i) quantifying the origin, mass, and upward transport of magmatic carbon from geothermal reservoirs; (ii) assessing the changes to the natural surface heat and mass flow of the Ohaaki Field following 20 years of production; (iii) establishing the utility of surface CO₂ flux and heat flow surveys to identify major upflow zones, estimate minimum mass flow, and determine the enthalpy of reservoirs; (iv) providing insight into the hydrothermal, structural and lithological controls over hydrothermal fluid flow; (v) demonstrating the influence of extinct silicic lava domes as important structural elements in the localisation of hydrothermal fluid flow; (vi) identifying the hydrostructural controls governing the spatial variability in the magnitude of pressure-induced ground subsidence, from which predictive models of subsidence risk may be defined, and; (vii) developing new technologies and characterising methods used for detailed assessment of surface heat and mass flow.

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Bussular, Camilla Zanon. "A amargura do Rio que era Doce : às margens da lama e dos processos de aprender a organizar." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2017. http://hdl.handle.net/10183/180841.

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O objetivo central da tese foi compreender como se configura a aprendizagem nos processos organizativos de desastres. Realizei uma pesquisa qualitativa à luz da teoria ator-rede como inspiração teórico-metodológica, a partir do crime-desastre da Samarco/Vale/BHP Billiton ocorrido em novembro de 2015. Na primeira discussão teórica da tese, busquei aproximar processualmente os atos de organizar e aprender, por meio do conceito de aprendizagem organizativa. Na segunda discussão teórica, analisei as questões contemporâneas sobre a temática dos desastres do Brasil, propondo que os desastres são efeitos disruptivos em uma rede de relações heterogêneas, desiguais, atemporais e multiterritoriais, sendo as vulnerabilidades e os perigos constituídos relacionalmente. A pesquisa foi constituída por uma fase preliminar/exploratória e três momentos de imersão no campo: na etapa preliminar realizei um aprofundamento empírico sobre os desastres, especialmente a partir de experiências brasileiras; os três momentos de imersão foram no caso do desastre das empresas, com enfoque para os desdobramentos do desastre no Estado do Espírito Santo. Ao longo do primeiro ano do desastre-crime da Samarco/Vale/BHP, coletei e analisei 1.297 documentos, entrevistas (formais e informais) e registros em diários de campo. Todos os dados foram inseridos no software de análise qualitativa Atlas.ti. A metodologia e a análise dos dados foram realizadas a partir do mapeamento das principais controvérsias que emergiram das relações entre os atores do estudo, uma das possibilidades da teoria ator-rede enquanto método e que se constitui uma das contribuições desta pesquisa A partir das discussões teóricas e empíricas, foi possível observar que os desastres geram uma latência organizativa, que se constitui num estado abstrato e transitório de disposição para aprender a organizar. Essa latência impulsiona os processos de aprendizagem organizativa, que são os modos de cooperar e se fazer coletivamente, em movimento e instáveis, cognoscíveis pelo aprender e pelos saberes-em-ato (knowing); eles são estabelecidos numa rede de relações heterogêneas em múltiplas formas de espacialidades, podendo se inscrever e formar uma tessitura de práticas, sendo que as condições de possibilidades para a sua realização e participação não são dadas, podendo também servir como um meio para superar, combater as desigualdades, e formar outros fazeres e práticas. Pelas imersões de campo, foi possível analisar que os processos de aprendizagem organizativa se configuraram de modo excludente, nos quais alguns atores (como os sujeitos atingidos pelo desastre das empresas) foram ausências-presentes nesses processos. Dada a dinâmica formada pela exclusão e pelas tensões originadas nos conflitos, desigualdades e divergências (controvérsias), os processos organizativos se tornaram múltiplos, oportunizando que os sujeitos excluídos de algumas práticas organizativas pudessem aprender a se organizar em outras relações, para superar e combater as desigualdades geradas nos desastres.
The main objective of the thesis was to understand how learning is configured in organizational processes of disasters. I conducted a qualitative research in the light of actor-network theory as a theoretical-methodological inspiration, starting from the Samarco/Vale/BHP Billiton crime-disaster that occurred in November of 2015. In the first theoretical discussion of the thesis, I tried to procedurally approach the acts of organizing and learning, through the concept of organizational learning. In the second theoretical discussion, I analyzed contemporary issues on Brazil's disasters, proposing that disasters are disruptive effects in a network of heterogeneous, unequal, timeless and multi-territorial relations, with vulnerabilities and dangers being constituted relationally. The research consisted of a preliminary/exploratory phase and three moments of immersion in the field: in the preliminary stage I realized an empirical deepening on the disasters, especially from Brazilian experiences; the three moments of immersion were in the case of the disaster of the companies, with focus on the unfolding of the disaster in the State of Espírito Santo. Throughout the first year of the Samarco/Vale/BHP crime-disaster, I collected and analyzed 1,297 documents, interviews (formal and informal) and records in field journals. All data were entered into the qualitative analysis software Atlas.ti. The methodology and data analysis were performed from the mapping of the main controversies that emerged from the relations between the actors of the study, one of the possibilities of actor-network theory as a method and that is one of the contributions of this research From the theoretical and empirical discussions, it was possible to observe that disasters generate an organizational latency, which constitutes an abstract and transitory state of disposition to learn how to organize. This latency drives the processes of organizational learning, which are ways of cooperating and doing collectively, moving and unstable, knowable by learning and knowing-in-act; they are established in a network of heterogeneous relations in multiple forms of spatiality, and can register and form a texture of practices, and the conditions of possibilities for their realization and participation are not given, and can also serve as a means to overcome, combat inequalities, and to form other doings and practices. Due to the field immersions, it was possible to analyze that organizational learning processes were configured in an exclusive way, in which some actors (such as the subjects affected by corporate disaster) were present-absences in these processes. Given the dynamics of exclusion and tensions arisen from conflicts, inequalities, and divergences (controversies), organizational processes became multiple, allowing the excluded subjects of some organizational practices to learn to organize in other relationships, to overcome and combat inequalities generated by disasters.

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Elomaa, Kaisa. "The risk of escape ovulation under treatment with low-dose combined oral contraceptives." Helsinki : University of Helsinki, 2001. http://ethesis.helsinki.fi/julkaisut/laa/kliin/vk/elomaa/.

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Leitão, Natalia de Jesus [UNESP]. "Dietas microencapsuladas: produção e avaliação para alimentação de larvas altriciais de peixes de água doce." Universidade Estadual Paulista (UNESP), 2013. http://hdl.handle.net/11449/104067.

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Este estudo teve como objetivo produzir e avaliar dietas microencapsuladas para larvas altriciais de peixes de água doce pela combinação dos processos de gelificação iônica e coacervação complexa. As microcápsulas foram formuladas para conter níveis de nutrientes baseados na composição de náuplios de artêmia. Cinco dietas microencapsuladas foram produzidas variando apenas o óleo incorporado: oliva, girassol, linhaça, sacha inchi e peixe. As dietas microencapsuladas foram avaliadas utilizando larvas de pacu Piaractus mesopotamicus e foram comparadas a dois tratamentos controle, um com náuplios de artêmia e outro com dieta comercial. Para tanto, foram considerados aspectos relacionados à aceitação das dietas, desempenho produtivo, alterações morfológicas do trato digestório e celularidade do músculo esquelético dos animais, além da expressão de genes relacionados com a miogênese e crescimento muscular. As dietas microencapsuladas apresentaram, de modo geral, 550 g kg–1 de proteína bruta, 240 g kg–1 de lipídios e 11 g kg–1 de cinzas, além de teores de umidade superiores a 850 g kg–1. Nenhuma das dietas microencapsulas foi rejeitada pelos animais, entretanto quantidades inferiores aos náuplios de artêmia foram ingeridas (p<0,05). Baixos valores de taxa de crescimento específico foram observados nos animais alimentados com as dietas microencapsulas, o que refletiu em ganho em peso inferior ao proporcionado pelos náuplios de artêmia e pela dieta comercial (p<0,05). Entre as dietas microencapsuladas, aquela produzida com óleo de peixe apresentou os mais baixos índices de crescimento e sobrevivência (p<0,05). As análises histológicas demonstraram atraso no desenvolvimento do intestino, fígado, pâncreas e estômago dos animais alimentados com as dietas microencapsuladas, assim como na musculatura...
This study aimed to produce and evaluate microencapsulated diets for altricial freshwater fish larvae by combining ionic gelation and complex coacervation processes. The microparticles were formulated to contain nutrient levels based on artemia nauplii composition. Five microencapsulated diets were produced varying only the oil source: olive, sunflower, linseed, sacha inchi and fish. Microencapsulated diets were evaluated using pacu Piaractus mesopotamicus larvae and compared to two feed controls, artemia nauplii and commercial diet. Therefore, we considered issues related to attractiveness of diets, growth performance, morphological changes of the digestive tract and skeletal muscle cellularity, and expression of genes related to myogenesis and muscle growth. Microencapsulated diets displayed in general 550 g kg–1 protein, 240 g kg–1 lipid and 11 g kg–1 of ash. Moisture content was higher than 850 g kg–1. Any of the microencapsulated diet was rejected by fish, however lower amounts then artemia nauplii were ingested (p<0.05). The specific growth rates of the animals fed with microencapsulated diets were lower than the control treatments, which also resulted in less weight gain (p<0.05). The comparison amongst the microencapsulated diets revealed that the diet produced with fish oil showed the lowest growth rate and survival (p<0.05). Histological analyzes indicated developmental delay in intestine, liver, pancreas and stomach of fish fed with microencapsulated diets, as well as skeletal muscle fibers in these fish. Higher frequency of small fibers (diameter ≤10 mm) was observed in the deep layer of the epaxial muscle... (Complete abstract click electronic access below)

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Leitão, Natalia de Jesus. "Dietas microencapsuladas : produção e avaliação para alimentação de larvas altriciais de peixes de água doce /." Jaboticabal, 2013. http://hdl.handle.net/11449/104067.

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Orientador: Maria Célia Portella
Banca: Carlos Raimundo Ferreira Grosso
Banca: Renata Guimarães Moreira
Banca: Maeli Dal Pai Silva
Banca: Elisabeth Criscuolo Urbinati
Resumo: Este estudo teve como objetivo produzir e avaliar dietas microencapsuladas para larvas altriciais de peixes de água doce pela combinação dos processos de gelificação iônica e coacervação complexa. As microcápsulas foram formuladas para conter níveis de nutrientes baseados na composição de náuplios de artêmia. Cinco dietas microencapsuladas foram produzidas variando apenas o óleo incorporado: oliva, girassol, linhaça, sacha inchi e peixe. As dietas microencapsuladas foram avaliadas utilizando larvas de pacu Piaractus mesopotamicus e foram comparadas a dois tratamentos controle, um com náuplios de artêmia e outro com dieta comercial. Para tanto, foram considerados aspectos relacionados à aceitação das dietas, desempenho produtivo, alterações morfológicas do trato digestório e celularidade do músculo esquelético dos animais, além da expressão de genes relacionados com a miogênese e crescimento muscular. As dietas microencapsuladas apresentaram, de modo geral, 550 g kg-1 de proteína bruta, 240 g kg-1 de lipídios e 11 g kg-1 de cinzas, além de teores de umidade superiores a 850 g kg-1. Nenhuma das dietas microencapsulas foi rejeitada pelos animais, entretanto quantidades inferiores aos náuplios de artêmia foram ingeridas (p<0,05). Baixos valores de taxa de crescimento específico foram observados nos animais alimentados com as dietas microencapsulas, o que refletiu em ganho em peso inferior ao proporcionado pelos náuplios de artêmia e pela dieta comercial (p<0,05). Entre as dietas microencapsuladas, aquela produzida com óleo de peixe apresentou os mais baixos índices de crescimento e sobrevivência (p<0,05). As análises histológicas demonstraram atraso no desenvolvimento do intestino, fígado, pâncreas e estômago dos animais alimentados com as dietas microencapsuladas, assim como na musculatura... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: This study aimed to produce and evaluate microencapsulated diets for altricial freshwater fish larvae by combining ionic gelation and complex coacervation processes. The microparticles were formulated to contain nutrient levels based on artemia nauplii composition. Five microencapsulated diets were produced varying only the oil source: olive, sunflower, linseed, sacha inchi and fish. Microencapsulated diets were evaluated using pacu Piaractus mesopotamicus larvae and compared to two feed controls, artemia nauplii and commercial diet. Therefore, we considered issues related to attractiveness of diets, growth performance, morphological changes of the digestive tract and skeletal muscle cellularity, and expression of genes related to myogenesis and muscle growth. Microencapsulated diets displayed in general 550 g kg-1 protein, 240 g kg-1 lipid and 11 g kg-1 of ash. Moisture content was higher than 850 g kg-1. Any of the microencapsulated diet was rejected by fish, however lower amounts then artemia nauplii were ingested (p<0.05). The specific growth rates of the animals fed with microencapsulated diets were lower than the control treatments, which also resulted in less weight gain (p<0.05). The comparison amongst the microencapsulated diets revealed that the diet produced with fish oil showed the lowest growth rate and survival (p<0.05). Histological analyzes indicated developmental delay in intestine, liver, pancreas and stomach of fish fed with microencapsulated diets, as well as skeletal muscle fibers in these fish. Higher frequency of small fibers (diameter ≤10 mm) was observed in the deep layer of the epaxial muscle... (Complete abstract click electronic access below)
Doutor

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Laureano, Fernando Verassani. "O registro sedimentar clástico associado aos sistemas de cavernas Lapa Doce e Torrinha, Município de Iraquara, Chapada Diamantina (BA)." Universidade de São Paulo, 1998. http://www.teses.usp.br/teses/disponiveis/44/44134/tde-22042013-164416/.

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A região de Iraquara situa-se na porção meridional da Bacia de Irerê, onde afloram as rochas carbonáticas neoproterozóicas da Formação Salitre (Grupo Una), formando um planalto bordeado pelas serras e morros desenvolvidas, principalmente, nas sequências mesoproterozóicas do Supergrupo Espinhaço. Neste platô carbonático são conhecidas dezenas de cavernas de grande porte, onde associam-se extensas pilhas de sedimentos clásticos, muitas vezes, preenchendo os condutos até o teto. O enfoque do presente trabalho foi de aplicar a metodologia de análise de fácies a estes sedimentos, nos dois maiores sistemas de cavernas desta região (Lapa Doce e Torrinha), de forma a promover uma caracterização sedimentológica e estratigráfica dos mesmos, disponibilizando sua inserção no quadro de evolução das cavernas e do relevo local. Foram individualizadas treze fácies sedimentares descritivas, baseando-se em critérios texturais e estruturas internas, as quais podem ser agrupadas em brechas, areias e lamas. Sucessões verticais destas fácies permitiram o reconhecimento de três associações de fácies (A, B e C), com a predominância de depósitos por suspensão, tração e por gravidade, respectivamente. Três estágios de sedimentação são propostos: (i) por atuação de rios subterrâneos; (ii) por atuação de cursos efêmeros em enchentes bruscas e (iii) pela injeção gradativa de fluxos de lama em condutos inundados. Os dados cronológicos disponíveis indicam a atuação deste último estágio a até o Pleistoceno terminal. A expressão regional deste registro leva a sugestão de mudanças climáticas envolvidas nas transições entre os estágios de sedimentação. Os dois primeiros estágios de sedimentação requerem um vazio inicial, com exposição sub-aérea, para instalação de rios subterrâneos, sendo característicos da zona vadosa. Uma ampliação paragenética é assumida durante o último estágio, dado as características dos sedimentos e a posição relativa do nível d\'água. A exposição vadosa destes condutos e o seu assoreamento estão temporalmente situados entre o início do entalhamento da Superfície Sul-Americana e a instalação da superfície desenvolvida sobre os carbonatos. A erosão parcial destes sedimentos está vinculada ao rebaixamento do nível de base local, gerado pela conexão do aquífero cárstico à bacia hidrográfica do rio Paraguaçu, através do entalhamento vertical da rochas siliclásticas, na borda leste do sinforme de Iraquara.
Neoproterozoic carbonate rocks of the Salitre Formation (Una Group), form an elevated plain in the Iraquara region, southern portion of the Irece Basin. Several kilometric caves are known in this area, most of which exhibit a sedimentary infilling which usually reaches the top of the conduits. This dissertation applied facies analysis to the sediments, along the tow longest cave systems of this region (Lapa Doce and Torrinha) in order to understand the sedimentology and stratigraphy of the caves, as well to relate sedimentation with cave development and geomorphological evolution. Thirteen facies have been described, based on textural parameters and internal structures. These facies fall into three groups: breccias, sands and muds. Vertical successions of these facies allowed the distinction of three facies associations, relate to suspension, traction, and gravity deposits. Three successive stages of sedimentation are proposed: (i) by subterranean rivers; (ii) by the action of ephemeral streams and (iii) by the gradual injection of mud flows through flooded conduits. Available chronological data indicate that this last stage was active until the end of Late Pleistocene. Climatic changes are invoked as responsible for these different sedimentary environments. The two first stages of sedimentation, of necessity, require the presence of air in the conduits, so that, deposition did not take place within a water-filled cavities. The third stage is compatible with hydraulic a paragenetic conditions leading to the upward expansion of the cave systems. Vadose exposure of these conduits and their silting-up were part of a continuous event, that occurred between the start of erosion of the Sul-Americana Surface and the installation of a younger surface, developed upon the carbonate rocks. Partial erosion of the cave sediments is linked to the lowering of the local base level, associated with the connection of the karstic aquifer to the Rio Paraguaçu basin, with the entrenchment of the underlying terrigenous rocks (Espinhaço Supergroup), that crop out along the eastern border of the Iraquara synform.

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Hölttä, Päivi. "Developmental aberrations of permanent teeth after high-dose anticancer therapy in childhood : a study on stem cell transplant recipients /." Helsinki : Helsinki University Printing House, 2005. http://ethesis.helsinki.fi/julkaisut/laa/hamma/vk/holtta/.

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Thesis (doctoral)--University of Helsinki, 2005.
At head of title: Institute of Dentistry, Department of Pediatric and Preventive Dentistry, University of Helsinki, Finland; Hospital for Children and Adolescents, University of Helsinki, Finland. Includes bibliographical references. Also available on World Wide Web.

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Hölttä, Päivi Alvesalo Lassi. "Developmental aberrations of permanent teeth after high-dose anticancer therapy in childhood a study on stem cell transplant recipients /." Helsinki : Helsinki University Printing House, 2005. http://ethesis.helsinki.fi/julkaisut/laa/hamma/vk/holtta/developm.pdf.

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Academic dissertation : University of Helsinki : 2005.
Textes et résumés en anglais. Pagination multiple pour les articles publiés en annexe. Bibiogr. p. 107-119. Bibliogr. à la suite des articles.

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Santos, Cíntia Pinheiro dos. "Desenvolvimento de metodologia para controle das larvas de Limnoperna fortunei com o uso de radiação ultravioleta e seus impactos sobre Microscystis aeruginosa potencialmente presentes na água superficial." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2011. http://hdl.handle.net/10183/37458.

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Este trabalho objetivou adaptar um método de controle de larvas do mexilhão dourado (Limnoperna fortunei) com a utilização de radiação ultravioleta e verificar seu efeito sobre cianobactérias e cianotoxinas presentes na água. Limnoperna fortunei (Dunker, 1857), conhecido vulgarmente como mexilhão dourado é proveniente do sudeste asiático. Foi, provavelmente, introduzido nos nossos mananciais, não intencionalmente, através da água de lastro, com os primeiros registros na América do Sul, em 1991, no Rio da Prata, nas proximidades de Buenos Aires, Argentina. No Brasil foi visto pela primeira vez na área do Delta do Jacuí, em frente ao porto de Porto Alegre, RS, no ano de 1998. Além de ameaçar à biodiversidade de ecossistemas, vem provocando a obstrução das tubulações e trocadores de calor junto às estações de tratamento de água e indústrias que utilizam água bruta para resfriamento. As estações de tratamento, além de enfrentarem problemas com o entupimento pelo mexilhão, defrontam-se também com as florações de cianobactérias. As florações, conhecidas também como blooms, são eventos de multiplicação e acumulação de microalgas ou cianobactérias nos corpos hídricos, que podem durar de algumas horas ao longo do dia a meses. As cianobactérias podem liberar cianotoxinas que estão presentes principalmente no interior das células, e são liberadas na lise celular, que ocorre principalmente por senescência natural. Os experimentos foram realizados em uma unidade piloto, onde concentrações conhecidas de larvas do mexilhão dourado foram submetidas a doses de radiação ultravioleta, na faixa de 200 a 800 mWs/cm2. As amostras de água bruta utilizadas nos testes foram avaliadas por meio de métodos analíticos adequados (APHA, 2005). Foram determinados os parâmetros de temperatura (°C), pH, turbidez (NTU), dureza (mgCaCO3/L) e sólidos suspensos (mg/L), os quais poderiam influenciar nas condições dos testes. As mesmas condições testadas para o mexilhão foram utilizadas nos experimentos com cianobactérias. As larvas de mexilhão dourado e a água bruta utilizada no experimento foram obtidos no delta do Jacui, Porto Alegre, Rio Grande do Sul, Brasil. A cianobactéria Microcystis aeruginosa, produtora de microcistina, foi cultivada em laboratório. A mortalidade instantânea das larvas aproximou-se dos 100% nas condições do teste com a dosagem de 781mWs/cm2 , com DL50 de 324 mWs/cm2. Na água residual dos experimentos de exposição à radiação UV, foram realizados ensaios ecotoxicológicos crônicos com Pimephales promelas, Ceriodaphnia dubia e Selenastrum capricornutum, a fim de detectar a presença de subprodutos que poderiam gerar toxicidade aos organismos de diferentes níveis tróficos. Os resultados desta avaliação ecotoxicológica não demonstraram toxicidade residual. Os dados obtidos demonstraram-se satisfatórios no controle daslarvas de mexilhão, entretanto não promoveram a lise das células de M. aeruginosa e a conseqüente liberação de microcistinas nas condições testadas.
L. fortunei (Dunker, 1857), commonly known as golden mussel comes from Southeast Asia. It might have been unintentionally introduced in our water sources through ballast water, with the first records in 1991, in Rio de la Plata, near Buenos Aires, Argentina, South America. In Brazil it was first seen in 1998, in Jacuí Delta, opposite Porto Alegre’s harbor. Besides threatening the biodiversity of ecosystems, this mussel has caused the obstruction of pipes and heat exchangers along the water treatment plants and industries that use raw water for cooling. Treatment plants facing problems with the clogging of mussels also have to contend with the cyanobacterial blooms. The blooms are events of multiplication and accumulation of algae or cyanobacteria in water bodies that can last from a few hours to days or months. The cyanobacteria may release cyanotoxins present mainly in cells and are released upon cell lysis, which occurs primarily by natural senescence. Thus, the aim of study is to adapt a control method of golden mussel larvae (L. fortunei) using ultraviolet radiation and verify its effect on cyanobacteria and cyanotoxins in the water. The experiments were performed in a pilot unit, where known concentrations of mussel larvae were subjected to doses of ultraviolet radiation ranging from 200 to 800 mWs/cm2, and the quality of water used, evaluated. The same conditions tested for the mussels were used in experiments with cyanobacteria. Mussel larvae and raw water used in the experiments were obtained from the Jacuí Delta, Porto Alegre, Rio Grande do Sul, Brazil. The cyanobacteria Microcystis aeruginosa, witch produces microcystin, was grown in culture in our laboratory. The instantaneous mortality of larvae was approximately 100% with 781mWs/cm2 in test conditions, with LD50 of 324 mWs/cm2. Ecotoxicological tests were performed with Pimephales promelas, Ceriodaphnia dubia, and Selenastrum capricornutum, to detect the presence of byproducts that could cause toxicity to organisms of different trophic levels in the residual water. The results of ecotoxicological evaluation showed no residual toxicity. The data showed to be satisfactory in larvae control, but did not cause lysis in cells of M. aeruginosa and the consequent release of microcystins in the water.

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Carlini, Mirco. "“Dove hai imparato a fare queste cose, piccola?” Localizzazione videoludica e Gender Translation Studies: un’analisi della saga di Tomb Raider." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2019. http://amslaurea.unibo.it/17815/.

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After a brief introduction to the gaming industry and the gaming localization industry, and a glimpse of the gender representation issue that in some ways persists to this day in the videogame world, this dissertation considers as its object of inquiry the Italian localization of the acclaimed Tomb Raider saga. Its main aim is to scrutinize the evolution of the titles’ main character, Lara Croft, with the objective of pinning down the gender-related issues that arise in the translation from English into Italian. Since the videogame industry has been marred for decades by what could be considered a serious issue with gender representation, this dissertation highlights the elements of game localization that can be taken into consideration to mitigate this issue. Through a discussion of the topics of fidelity and culturalization, it is argued that by following the disruptive and revolutionary principles theorized by the feminist scholars that started Gender Translation Studies, the translator could contribute to reduce the discriminatory and sexist content that the analysis shows could be, even inadvertently, introduced during the translation process. To this end, the global intent of fidelity towards the translation project and the translator-client relationship would still be maintained, but the translator would be given greater liberty to commit to choices as dictated by a newfound sensitivity towards gender-related issues, with the ever-present assurance that the look and feel of the final product would not be compromised in any way.

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Hayd, Liliam de Arruda [UNESP]. "Ciclo de muda e metabolismo durante o desenvolvimento larval do camarão-da-amazônia Macrobrachium amazonicum (Heller, 1862)." Universidade Estadual Paulista (UNESP), 2007. http://hdl.handle.net/11449/100232.

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Universidade Estadual Paulista (UNESP)
O estudo teve por objetivo descrever o ciclo de muda e estudar o metabolismo nas fases iniciais do desenvolvimento ontogenético de Macrobrachium amazonicum. O trabalho está organizado em cinco capítulos. O capítulo 1 apresenta uma introdução geral, apresentando os estudos inerentes à M. amazonicum e o programa de tecnologia onde este estudo esta inserido. No capítulo 2 estão descritos os estágios do ciclo de muda de M. amazonicum. As descrições foram determinadas e documentadas fotograficamente em intervalos diários usando o telson como principal região de referência e aplicando o sistema de classificação de Drach, observando as principais mudanças que ocorrem na epiderme e na cutícula. O desenvolvimento é rápido (1-2 dias ou 2-4 dias por instar larval a 29 e 21°C, respectivamente). Foram descritos os seguintes estágios de muda, A/C (pós-muda/intermuda combinados), D (pré-muda) e E (ecdise). Estima-se que a pós-muda/intermuda (A/C) ocupe cerca de 40-50% do total de duração do instar enquanto que o período da pré-muda (D) requer mais que a metade do tempo nas temperaturas experimentais. O capítulo 3 apresenta a descrição do metabolismo de embriões, larvas e pós-larvas (PL com 1, 7 e 14 dias após a metamorfose) nas fases iniciais do desenvolvimento ontogenético. O peso seco, consumo de oxigênio, excreção de amônia total–N e taxa atômica O:N foram determinados. Os animais em estágio de muda A/C foram separados conforme o estágio de desenvolvimento larval e colocados dentro de câmaras respirométricas (30mL) por 2h para quantificar as taxas metabólicas. Após este período, as amostras foram analisadas pela titulação de Winkler e método de Koroleff para o consumo de oxigênio e nitrogênio amoniacal, respectivamente. As taxas metabólicas foram expressas como taxas individuais e peso-específico...
The moulting cycle was studied in laboratory-reared larvae of the Amazon River prawn, Macrobrachium amazonicum. Using the telson as main reference region and applying Drach’s classification system, we checked twice daily the epidermis and cuticle and documented major structural changes such as the retraction of epidermal tissues from the cuticle and setal development. Rapid development (1-2d or 3-4d per larval instar at 29 and 21°C, respectively), a thin and little structured larval integument, and gradual rather than abrupt integumental changes allowed for only a coarse classification of the moulting cycle with three principal stages, A-C (postmoult and intermoult stages combined), D (premoult), and E (ecdysis). These periods could be morphologically further divided into substages; however, without providing a definite timing for their transitions. At early postmoult (stage A), the cuticle is still thin and water is taken up, so that the larval body expands and rapidly attains its final size and shape. The epidermal tissues reveal at this stage a spongy structure with numerous lacunae. During later postmoult (stage B) and throughout intermoult (stage C), the larvae reinforce the cuticle, while the epidermis shows an increasing condensation with reduced lacunar spaces and conspicuous tissue growth. Early premoult (substage D0) begins with a retraction of the epidermis from the cuticle (apolysis), which is first visible at the setal bases. During intermediate premoult (substage D1), epidermal invaginations take place, leading to a substantial enlargement of the epidermal surface and initiating the formation of new setae and appendages (setogenesis, morphogenesis). Subsequently, a thin new cuticle is secreted on the epidermal surface (substages D2-4). Moulting (stage E) is a very short process, which usually takes only a few minutes ...(Complete abstract, click electronic access below)

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Barros, Helenice Pereira de [UNESP]. "Alimentação de Macrobrachium rosenbergii (De Man, 1879)(crustacea, palaemonidae) durante a fase larval: efeitos da densidade de náuplios de Artemia, do tamanho das partículas de ração, do tipo de alimento e do fotoperíodo." Universidade Estadual Paulista (UNESP), 2001. http://hdl.handle.net/11449/144131.

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A freqüência de aceitação de alimento (FAA) por larvas de M. rosenbergii foi utilizada como medida para determinar o tamanho de partícula e o tipo de alimento mais adequados para cada estágio de desenvolvimento. Foram testados quatro classes de tamanho de partículas (250-425; 425-710; 710-1000 e 1000-1190 mm) de dois tipos de ração (seca e úmida). Verificou-se também a freqüência de aceitação das duas rações e de náuplios de Artemia em cada estágio larval. A freqüência de aceitação foi obtida pela avaliação qualitativa da ingestão de cada alimento pelas larvas por meio da observação do trato digestório das mesmas sob estereomicroscópio. Não houve relação significativa (P < 0,01) entre o tamanho das partículas na freqüência de aceitação das rações pelas larvas no decorrer do desenvolvimento. Náuplios de Artemia foram significativamente mais ingeridos por larvas entre os estágios II e VII; aceitação similar para a ração úmida e seca foi obtida a partir dos estágios VII e IX, respectivamente. Verificou-se que o alimento inerte foi capturado e ingerido por mais de 50% das larvas apenas a partir dos estágios VII (ração úmida) e VIII (ração seca). Nossos resultados indicam que a complementação da dieta com alimento inerte deve se iniciar a partir do estágio VII
The functional response (relationship between ingestion rate and food concentration) was determined for each larval stage of Macrobrachium rosenbergii. Artemia nauplii were supplied at six different densities: 2, 4, 6, 8, 10 and 12 ind/mL. The nauplii were counted manually using a Pasteur pipette and placed in Petri dishes containing 40 mL of brackish water (12‰). A single Macrobrachium rosenbergii larvae was placed in each Petri dish and after 24 hours the leftover nauplii were counted. Daily average ingestion rate by larva was calculated for each zoeal stage. Consumption pattern was defined by the model I = Im(1-e-kP). Ingestion rate increased with food density in the medium. The best relationship between predator and prey seemed to occur during stages IV and V. The high values for maximum ingestion (Im) and the low values for constant k obtained in the last larval stages indicate the necessity of supplementary diet during the final stages of development

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Barros, Helenice Pereira de. "Alimentação de Macrobrachium rosenbergii (De Man, 1879)(crustacea, palaemonidae) durante a fase larval : efeitos da densidade de náuplios de Artemia, do tamanho das partículas de ração, do tipo de alimento e do fotoperíodo /." Jaboticabal, 2001. http://hdl.handle.net/11449/144131.

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Orientador: Wagner Cotroni Valenti
Resumo: A freqüência de aceitação de alimento (FAA) por larvas de M. rosenbergii foi utilizada como medida para determinar o tamanho de partícula e o tipo de alimento mais adequados para cada estágio de desenvolvimento. Foram testados quatro classes de tamanho de partículas (250-425; 425-710; 710-1000 e 1000-1190 mm) de dois tipos de ração (seca e úmida). Verificou-se também a freqüência de aceitação das duas rações e de náuplios de Artemia em cada estágio larval. A freqüência de aceitação foi obtida pela avaliação qualitativa da ingestão de cada alimento pelas larvas por meio da observação do trato digestório das mesmas sob estereomicroscópio. Não houve relação significativa (P < 0,01) entre o tamanho das partículas na freqüência de aceitação das rações pelas larvas no decorrer do desenvolvimento. Náuplios de Artemia foram significativamente mais ingeridos por larvas entre os estágios II e VII; aceitação similar para a ração úmida e seca foi obtida a partir dos estágios VII e IX, respectivamente. Verificou-se que o alimento inerte foi capturado e ingerido por mais de 50% das larvas apenas a partir dos estágios VII (ração úmida) e VIII (ração seca). Nossos resultados indicam que a complementação da dieta com alimento inerte deve se iniciar a partir do estágio VII
The functional response (relationship between ingestion rate and food concentration) was determined for each larval stage of Macrobrachium rosenbergii. Artemia nauplii were supplied at six different densities: 2, 4, 6, 8, 10 and 12 ind/mL. The nauplii were counted manually using a Pasteur pipette and placed in Petri dishes containing 40 mL of brackish water (12‰). A single Macrobrachium rosenbergii larvae was placed in each Petri dish and after 24 hours the leftover nauplii were counted. Daily average ingestion rate by larva was calculated for each zoeal stage. Consumption pattern was defined by the model I = Im(1-e-kP). Ingestion rate increased with food density in the medium. The best relationship between predator and prey seemed to occur during stages IV and V. The high values for maximum ingestion (Im) and the low values for constant k obtained in the last larval stages indicate the necessity of supplementary diet during the final stages of development
Doutor

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Briot, Danielle. "Génèse d'une série alcaline intraplaque continentale : étude géochimique (éléments traces et isotopes SR-ND-O) du volcan des Monts Dore (Massif central français)." Clermond-Ferrand 2, 1988. http://www.theses.fr/1988CLF21107.

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Le stratovolcan des Mont Dore (massif central français) est caractérisé par l'existence d'une caldera, par l'abondance des laves de composition globalement intermédiaire trachyandesitique et par la coexistence de laves sur- et sous-saturées. Il s'est édifié en deux temps. De 3 a 1;5 ma, l'activité se concentre au niveau des volcans septentrionnaux (Mont Dore s. S. , d'ordanche, aiguiller). Cette période est marquée par l'effondrement de la caldera de la haute-Dordogne et l'émission de rhyolites (ponces rhyolitiques de la grande nappe, dôme de la Gacherie. . . ). De 0;9 a 0;25 ma, le volcan du Sancy puis le massif adventif s'édifient au sud des structures précedentes. L'étude géochimique (isotopes du sr, du nd et de l'oxygène associes aux éléments en trace) des basaltes s. L. Met en évidence une évolution par cristallisation fractionnée d'olivine et de clinopyroxenes (+ ou - opaques) depuis les basanites jusqu'aux hawaiites. Les laves trachyandesitiques hétérogènes sont marquées par des déséquilibres minéralogiques, des phénomènes complexes de brassage mécanique de magmas, associés à l'assimilation de xenocristaux, de cumulats, de roches subvolcaniques et de socle. L'expulsion de fluides et des liquides résiduels lors de la cristallisation plus ou moins rapide des inclusions comagmatiques basiques et postérieurement à leur incorporation dans un magma trachytisque joue un rôle important dans la genèse d'inclusions particulières, préalablement interprérees comme des "liquides fractionnés". Au vu des données isotopiques, les trachyandesites basiques ne peuvent être le résultat d'un simple mélange abouti entre deux magmas. L'abondance des trachyandesites ne serait qu'un artefact dû aux processus de brassage mécanique de magmas de realimentation périodique des réservoirs magmatiques. Les données isotopiques sur les ponces et dômes rhyolitiques (**(87)sr/**(86)sr et **(143)nd/**(144)nd) excluent une origine par anatexie généralisée de la croute granitique mais montrent l'existence d'une contamination par la croute granito-gneissique. Les trachyphonolites et phonolites sont issus de la cristallisation fractionnée d'amphibole, de sphène et de feldspath potassique a partir des basanites et tephrites. Un modèle évolutif de réservoir magmatique dans la croute supérieure est proposé en fonction de l'âge, de la nature et de la répartition spatiale des produits émis en surface. A partir de quelques données géochimiques sur les peridotites et les basaltes du massif central et des données géophysiques disponibles, des esquisses de manteau sous cette région volcanisée sont également proposées

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Young, Kirby D. "Deformation, lava dome evolution, and eruption cyclicity at Merapi Volcano, Indonesia." 2007. http://etda.libraries.psu.edu/theses/approved/WorldWideIndex/ETD-2196/index.html.

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Young, Kriby D. "Deformation, lava dome evolution, and eruption cyclicity at Merapi Volcano, Indonesia." 2007. http://etda.libraries.psu.edu/theses/approved/WorldWideIndex/ETD-2196/index.html.

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"Spatial variations of rockfalls from a growing lava dome: Soufriere Hills Volcano, Montserrat." STATE UNIVERSITY OF NEW YORK AT BUFFALO, 2009. http://pqdtopen.proquest.com/#viewpdf?dispub=1464811.

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Vöge, Malte [Verfasser]. "Doppler radar monitoring of lava dome processes at Merapi Volcano, Indonesia / vorgelegt von Malte Vöge." 2007. http://d-nb.info/985022418/34.

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"Transitions in Eruption Style at Silicic Volcanoes: From Stable Domes to Pyroclastic Flows and Explosive Plumes." Doctoral diss., 2016. http://hdl.handle.net/2286/R.I.40333.

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abstract: Silicic volcanoes produce many styles of activity over a range of timescales. Eruptions vary from slow effusion of viscous lava over many years to violent explosions lasting several hours. Hazards from these eruptions can be far-reaching and persistent, and are compounded by the dense populations often surrounding active volcanoes. I apply and develop satellite and ground-based remote sensing techniques to document eruptions at Merapi and Sinabung Volcanoes in Indonesia. I use numerical models of volcanic activity in combination with my observational data to describe the processes driving different eruption styles, including lava dome growth and collapse, lava flow emplacement, and transitions between effusive and explosive activity. Both effusive and explosive eruptions have occurred recently at Merapi volcano. I use satellite thermal images to identify variations during the 2006 effusive eruption and a numerical model of magma ascent to explain the mechanisms that controlled those variations. I show that a nearby tectonic earthquake may have triggered the peak phase of the eruption by increasing the overpressure and bubble content of the magma and that the frequency of pyroclastic flows is correlated with eruption rate. In 2010, Merapi erupted explosively but also shifted between rapid dome-building and explosive phases. I explain these variations by the heterogeneous addition of CO2 to the melt from bedrock under conditions favorable to transitions between effusive and explosive styles. At Sinabung, I use photogrammetry and satellite images to describe the emplacement of a viscous lava flow. I calculate the flow volume (0.1 km3) and average effusion rate (4.4 m3 s-1) and identify active regions of collapse and advance. Advance rate was controlled by the effusion rate and the flow’s yield strength. Pyroclastic flow activity was initially correlated to the decreasing flow advance rate, but was later affected by the underlying topography as the flow inflated and collapsed near the vent, leading to renewed pyroclastic flow activity. This work describes previously poorly understood mechanisms of silicic lava emplacement, including multiple causes of pyroclastic flows, and improves the understanding, monitoring capability, and hazard assessment of silicic volcanic eruptions.
Dissertation/Thesis
Doctoral Dissertation Geological Sciences 2016

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Brož, Petr. "Maké sopky na Marsu: obrazová analýza, numerické modelování a srovnání s pozemskými analogy." Doctoral thesis, 2015. http://www.nusl.cz/ntk/nusl-350992.

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Small-scale volcanoes represent diverse group of landforms which vary in morphology, morphometry, and mechanisms of their formation. They are the most common volcanic form on Earth, and their existence and basic characteristics were also predicted for Mars. Availability of high-resolution image data now allows to search, identify and interpret such small volcanic features on the martian surface. This thesis extends our knowledge about the small-scale volcanoes with the following objectives: (a) to document the existence of martian analogues to some of the terrestrial volcanoes, in particular scoria cones, tuff cones, tuff rings and lava domes; (b) to establish their morphological and morphometrical parameters; and (c) to examine the effect of environmental factors, which differ on Earth and Mars, on the mechanisms of formation of the scoria cones. Interpretation of remote sensing images and digital elevation models reveals that scoria cones, tuff rings and cones, and lava domes exist on different parts of the martian surface and, in some cases, far away from previously well-known volcanic provinces. Scoria cones have been identified in the volcanic field Ulysses Colles situated within the Tharsis volcanic province; tuff cones and tuff rings have been found in the Nephenthes/Amenthes region at the...

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Liz, Guilherme Marques Mouta. "Conceção de um Sistema para Poupança de Água para Máquinas de Lavar Roupa Industriais." Master's thesis, 2020. http://hdl.handle.net/10362/108678.

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A problemática do aquecimento global e das alterações climáticas inerentes têm sido assuntos de crescente debate nos últimos anos, sendo a disponibilidade de água doce um dos focos de maior preocupação. O forte crescimento populacional que se tem vindo a verificar e, consequentemente, a crescente demanda de água e energia tem vindo a colocar cada vez mais pressão sobre os recursos hídricos disponíveis. Embora 2/3 do planeta Terra sejam cobertos por água, somente 2,5 % da totalidade da água existente representa água doce, sendo que apenas uma fração desta se encontra disponível para extração e consumo. Com isto, prevê-se que no futuro próximo este recurso fundamental para a maioria dos seres vivos se venha a tornar um recurso escasso. Um setor de atividade comercial cujo consumo de água é elevado é o setor das lavandarias que, na União Europeia, contabiliza um consumo anual de aproximadamente 42 milhões de metros cúbicos de água. O trabalho desenvolvido na presente dissertação tem como objetivo a máxima redução possível do consumo de água em estabelecimentos comerciais como lavandarias. Para tal, foi projetado um sistema modular de poupança de água para funcionamento em conjunto com as máquinas de lavar roupa industriais presentes no referido tipo de estabelecimentos. No desenvolvimento do projeto adotaram-se diversas ferramentas de apoio à decisão na conceção de produto, onde se podem salientar as metodologias sugeridas em Product Design and Development e na Teoria Axiomática de Projeto. Desta forma, o produto obtido trata-se de um dispositivo de poupança de água através do armazenamento e reutilização de água residual proveniente de fases menos contaminadas do ciclo de lavagem. Com a implementação do dispositivo projetado para funcionamento com uma máquina de lavar até 25 kg de capacidade, espera-se uma redução de cerca de 30% do consumo de água em cada ciclo de lavagem realizado. No decorrer deste projeto, chegou-se à conclusão de que nenhuma solução com um maior nível de complexidade em termos de componentes e processos seria adequada, uma vez que seria economicamente inviável devido ao atual preço da água. De facto, numa lavandaria o custo do consumo de água não é dos principais encargos. Com isto, no final conclui-se que atualmente se verifica um preço da água demasiado reduzido para que a implementação deste tipo de equipamento faça sentido do ponto de vista económico. No entanto, ignorando esta última componente e evidenciando a motivação ambiental do projeto, é de salientar que com um sistema relativamente simples é possível alcançar uma redução do consumo de água por parte da lavandaria de cerca de 30 %, conseguindo uma melhor gestão dos recursos hídricos.

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Dissertations / Theses on the topic 'Lava Dome'

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