Magma-crust interaction in magma reservoirs and conduits is a crucial process during magma evolution and ascent. This interaction is recorded by crustal xenoliths that frequently show partial melting, inflation and disintegration textures. Frothy xenoliths are widespread in volcanic deposits from all types of geological settings and indicate crustal gas liberation. To unravel the observed phenomena of frothy xenolith formation we experimentally simulated the behaviour of crustal lithologies in volcanic conduits. We subjected various sedimentary lithologies to elevated temperature (maximum 916 °C) and pressure (maximum 160 MPa) in closed-system autoclaves. Experimental conditions were held constant between 24h and 5 days. Controlled decompression to atmospheric pressure then simulated xenolith ascent. Pressure release was a function of temperature decline in our setup. Temperature lapse rate proceeded exponentially; the mean rate during the first 30 minutes was 17.8 ˚C/min and the mean decompression rate during the same interval was 3.0 MPa/min, eventually reaching room temperature after approximately 5.5 hours of slow cooling. The experimental products have been analysed for internal textures by synchrotron X-ray μ-CT at a resolution of 3.4 – 9 microns/pixel. This method permits visualisation and quantification of vesicle volumes, -networks and-connectivity in 3D without destroying the sample. Experimental products closely reproduced textures of natural frothy xenoliths in 3D and define anevolutionary sequence from partial melting to gas exsolution and bubble nucleation that eventually leads to the development of three-dimensional bubble networks. Experimental P-T-t conditions and especially rock lithology proved decisive for degassing behaviour and ensuing bubble nucleation during decompression. Progressive bubble nucleation leads to subsequent bubble coalescence to form interconnected bubble networks. This, in turn, enables efficient gas liberation and release. Our results attest to significant potential of even very common crustal rock types to release volatiles and develop interconnected bubble networks upon heating and decompression in magmatic systems. Crustal volatile input from xenoliths affects magma rheology and may drive magmas to sudden explosive eruptions. Our experiments offer insight into the mechanism of how such crustal volatile liberation is accomplished.

Cette étude traite de la dynamique des éruptions volcaniques explosives, depuis les mécanismes de sub-surface jusqu'aux processus d'émission et de dispersion des pyroclastes. A cet effet un radar Doppler sol est utilisé (VOLDORAD), lequel renseigne sur la charge / vitesse des ejectas. Les données sont intégrées avec d'autres techniques géophysiques, et des modèles numériques sont développés afin de simuler les émissions pyroclastiques, générer des signaux radar synthétiques, pour finalement améliorer notre compréhension des processus qui leurs sont sous-jacents. L'Arenal (Costa Rica) est utilisé comme volcan cible, où de fréquentes éruptions de faible magnitude émettent des panaches de cendres et des projections balistiques jusqu'à quelques centaines de mètres au-dessus de l'évent. Dans un premier temps, nous combinons des données sismiques et radar afin d'explorer la relation entre les processus de conduit et les émissions pyroclastiques. Leurs interactions complexes sont interprétées via un modèle conceptuel, lequel décrit les fractures parsemant le bouchon de lave comme responsables du dégazage du système, et en retour des signaux sismiques et radar collectés (ces derniers dépendants de la charge en cendres des émissions de gaz). Par ailleurs, nous investiguons la dynamique des émissions pyroclastiques à travers l'étude de radargrammes Doppler. La distribution spatio-temporelle de la vitesse des ejectas indique l'existence de deux phénomènes aux dynamiques distinctes. Des modélisations numériques permettant la reconstruction de signaux synthétiques indiquent qu'il s'agit de l'émission simultanée de blocs balistiques et de panaches de cendres. Une procédure d'inversion de type Monte Carlo couplée d'un algorithme d'optimisation permet de retrouver les radargrammes synthétiques qui reproduisent au mieux ceux observés. Les résultats apportent des contraintes sur divers paramètres éruptifs, tels que les tailles, trajectoires, vitesses des ejectas et des gaz, ainsi que la vitesse / direction de dispersion des panaches de cendres par le vent. Enfin, nous discutons du potentiel des radars Doppler appliqués à la surveillance opérationnelle des émissions volcaniques. En particulier, la possibilité de quantifier les masses éjectées dans l'atmosphère ou retombant sur les flancs du volcan, fournit des paramètres éruptifs à la source pouvant alimenter les modèles de dispersion de panaches de cendres.

Training studies involving competitive runners and road cyclists have shown substantial gains in sprint and endurance performance when sessions of high-intensity interval training were added to their usual training in the competitive phase of a season. Further research has shown large performance benefits in sprint and endurance power (7 - 9%) when cyclists combined explosive single-leg jumps with cycling-specific high-intensity interval training during a competitive season. The aim of the present study was to assess the contribution of the jumps to the gains in performance in competitive cyclists in a randomized control trial.The training protocol for the control group was based on previous experimental work in which the control group (n=8) completed cycle specific interval training followed by a series of explosive single-leg jumps. The experimental group (n=7) carried out the same cycle specific interval training but did not participate in the explosive single-leg jumps. While the current study did not use a true control group, the investigation was carried out in the knowledge that a combination of high intensity interval cycling and explosive single-leg jumps causes changes positive changes in performance. Participants took part in 10 x 30-min sessions consisting four sets of high intensity intermittent cycling (4 x 30-s maximum efforts at 50 - 60 min-1 alternating with 30-s recovery). Between each set of 4 x 30 s sprints the control (ballistic) group carried out one set of explosive single-leg jumps (20 for each leg), while the experimental (continuous) group cycled for 20 s at 50 - 60 min-1.Before and after the training period all cyclists completed an incremental peak power test for assessment of VO2max, lactate threshold, exercise economy and peak power, a 30 s Wingate sprint test and a 20 km time-trial. Relative to the control group the percent mean changes (±90% confidence limits) in the experimental group were: power at 4-mM lactate, -4.2 (±6.3); VO2max, -3.1 (±3.7); mean time-trial power, -0.7 (± 4.7); peak incremental power, -1.7; (±5.0); power at 80% max heart rate, -2.8; (±5.6); Wingate peak power, -4.2; (±7.8). We conclude that high-intensity training may improve performance but the combination of high-intensity training and explosive resistance training in the competitive phase is likely to produce greater gains in trained cyclists than high intensity cycling alone.

The broad aim of this thesis was to progress understanding of the neuromechanics of joint stability and injury mechanisms by investigating the interactions between neuromuscular function and balance perturbations as well as the influence of sex and fatigue on these variables. Knee extensor (KE) and plantar flexor (PF) isometric strength parameters (maximum voluntary torque (MVT), explosive voluntary torque (EVT)) were related in young healthy adults. EVT of KE and PF were correlated at 4/5 time points during the rising torque-time curve for all absolute (r = 0.488-0.755) and relative (to body mass (BM) (r = 0.517-0.669) and MVT (r = 0.353-0.480)) expressions of EVT. These results suggest that KE and PF function is related for both maximum and explosive torque. Males were stronger for KE (+89%) and PF (+55%) than females. Males also displayed greater EVT at all time points in KE (+57-109%) and at 50-150 ms in PF (+33-52%). When MVT and EVT were normalised to BM, males continued to be stronger at all time points in KE (+23-60%) and from 100-150 ms (18-20%) in PF. No sex differences were found when EVT was normalised to MVT. Furthermore, sex differences were discovered in muscle morphology. Females had a smaller knee flexor (KF):KE size ratio, a proportionately small sartorius (SA) and gracilis (GR) and a proportionately larger vastus lateralis (VL), potentially predisposing females to greater risk of ACL injury. Females had a larger biceps femoris long head (BFlh) as a proportion of the KF than males, which may contribute to the higher risk of hamstring strain injury (HSI) in males. Regarding explosive performance and perturbation response, explosive PF torque had a weak to moderate correlation with COM displacement (COMD) from 400-500 ms (r = -0.346 to -0.508) and COM velocity (COMV) from 300-500 ms (r = -0.349 to -0.416), with weaker correlations between explosive KE torque and COMV at 400 ms (r = -0.381 to -0.411) but not with COMD. These findings suggest that greater explosive torque results in better control of the COM in response to unexpected perturbations. The effects of football simulated fatigue on these factors resulted in reduced maximal KF and KE torque. However, football simulated fatigue was not found to reduce EVT of either muscle group, or explosive H/Q ratio. Football simulated fatigue resulted in impaired balance response to unexpected perturbation in the posterior but not the anterior direction.

This thesis examined the change in skeletal muscle architecture with contractile force production, the relationship of architecture with muscle strength parameters and if muscle tendinous tissue stiffness determines in vivo explosive strength (i.e. rate of torque development, RTD). Muscle and tendinous tissue adaptations to contrasting strength training regimes, and the potential capacity of these tissues to adapt following chronic strength training were also explored. Quadriceps femoris fascicle length (FL) decreased, while the pennation angle (PA) increased in a curvi-linearly manner from rest to maximal voluntary contraction (MVC) torque. Consequently, effective physiological cross-sectional area (effPCSA) during MVC was 27% greater than at rest, although effPCSA measured at rest and during MVC had similar correlations to maximal strength. In the earliest phase of contraction, FL, but not PA, was negatively related (R2=0.187) to voluntary RTD. Neither FL nor PA was related to maximal isometric or dynamic strength. Muscle-tendon unit (MTU) and patellar tendon (PT) stiffness were unrelated to voluntary and evoked RTD. Relative PT stiffness was also unrelated to relative RTD, although relative MTU stiffness was related to voluntary RTD (25-55%MVT, R2≤0.188) and evoked RTD (5-50%MVT, R2≤0.194). MTU stiffness increased after sustained-contraction (SCT, +21%), though not explosive-contraction strength training (ECT). PT stiffness increased similarly after ECT (+20%) and SCT (+16%), yet neither induced tendon hypertrophy. SCT produced modest muscle (+8%) and aponeurosis (+7%) hypertrophy. Chronic strength trained (CST: >3 years) males had substantially greater muscle and aponeurosis size, but similar tendon size as untrained controls (UNT) and short-term (12 weeks) strength trained (STT) individuals. Between these groups, at the highest common force, MTU stiffness was indifferent, while PT stiffness was similarly greater in STT and CST than UNT. These results suggest FL and PA have little influence on muscle strength and tendon stiffness has no influence on RTD. Maximum strength negated any qualitative influence of MTU stiffness on in vivo RTD. Component MTU tissues (muscle-aponeurosis vs. external tendon) adapt differentially depending on the strength training regime. Specifically, free tendon appeared to adapt to high magnitude loading, while loading duration is also an important stimulus for the muscle-aponeurosis. However, chronic strength training was not concordant with greater higher force MTU stiffness, and does not further increase higher force PT stiffness beyond the adaptations that occur after 12 weeks of strength training. Finally, no evidence was found for tendon hypertrophy in response to strength training.

xvi, 182 p. : col. ill. / Volatile components (H 2 O, CO 2 , S, Cl) dissolved in magmas influence all aspects of volcanic activity from magma formation to eruption explosivity. Understanding the behavior of volatiles is critical for both mitigating volcanic hazards and attaining a deeper understanding of large-scale geodynamic processes. This work relates the dissolved volatile contents in olivine-hosted melt inclusions from young volcanics in the Central Oregon and Northern California Cascades to inferred magmatic processes at depth and subsequent eruptive activity at the surface. Cinder cone eruptions are the dominant form of Holocene volcanism in the Central Oregon segment of the High Cascades. Detailed field study of deposits from three cinder cones in Central Oregon reveals physical and compositional similarities to explosive historic eruptions characterized as violent strombolian. This work has important implications for future hazard assessments in the region. Based on melt inclusion data, pre-eruptive volatile contents for seven calc-alkaline cinder cones vary from 1.7-3.6 wt.% H 2 O, 1200-2100 ppm S, and 500-1200 ppm Cl. Subarc mantle temperatures inferred from H 2 O and trace elements are similar to or slightly warmer than temperatures in other arcs, consistent with a young and hot incoming plate. High-magnesium andesites (HMA) are relatively rare but potentially important in the formation of continental crust. Melt inclusions from a well-studied example of HMA from near Mt. Shasta, CA were examined because petrographic evidence for magma mixing has stimulated a recent debate over the origin of HMA magmas. High volatile contents (3.5-5.6 wt.% H 2 O, 830-2900 ppm S, 1590-2580 ppm Cl), primitive host crystals, and compositional similarities with experiments suggest that these inclusions represent mantle-derived magmas. The Cascades arc is the global end member, warm-slab subduction zone. Primitive magma compositions from the Cascades are compared to data for arcs spanning the global range in slab thermal state to examine systematic differences in slab-derived components added to the mantle wedge. H 2 O/Ce, Cl/Nb, and Ba/La ratios negatively correlate with inferred slab surface temperatures predicted by geodynamic models. Slab components become increasingly solute-rich as slab surface temperatures increase from ∼550 to 950°C at 120 km depth. This dissertation includes previously published and unpublished co-authored material. / Committee in charge: Dr. Paul J. Wallace, Chair and Advisor; Dr. Katharine Cashman, Member; Dr. Ilya Bindeman, Member; Dr. Richard Taylor, Outside Member

Plusieurs volcans andésitiques dans le monde connaissent des périodes d’activité en système ouvert pendant plusieurs années, décennies voire siècles, qui sont caractérisées par des manifestations éruptives persistantes d’intensité fluctuante et ponctuées de phases explosives violentes et dangereuses, souvent accompagnées d’écoulements pyroclastiques. La compréhension de la dynamique et de l’origine de ces paroxysmes en système ouvert est un enjeu majeur de la recherche volcanologique dans le but d’améliorer la surveillance de ce type d’activité. Le Tungurahua en Equateur est un excellent exemple pour étudier un système andésitique ouvert : entré en activité en 1999, le volcan a connu une phase paroxysmale en août 2006, avec l’émission d’un panache éruptif de 15 km de hauteur et la mise en place d’écoulements pyroclastiques. Les objectifs de cette thèse sont, à partir de l’étude du dépôt de retombée, d’explorer la dynamique d’un volcan andésitique fonctionnant en système ouvert en étudiant le cas du paroxysme explosif du Tungurahua et de développer une méthode de suivi haute-résolution des budgets éruptifs massiques, transposable à différentes phases éruptives et différents volcans. A l’aide d’une déconvolution automatique des distributions granulométriques bimodales du dépôt, deux sous-populations ont été caractérisées et quantifiées. Ces dernières reflètent la syn-sédimentation de particules grossières depuis le panache éruptif, et de particules fines depuis des nuages co-écoulements pyroclastiques. Cette analyse granulométrique couplée à l’étude de l’amincissement du dépôt indiquent un volume total minimum de 42×106 m3 et un panache de 16-18 km au dessus du cratère. Cette éruption est classée comme une VEI 3 de type subplinien. Un nouveau protocole d’analyses de type et densité de clastes révèle une distribution sigmoïdale des densités des particules vésiculées avec la granulométrie. Cette loi empirique permet de déterminer la charge massique de chaque classe de constituants latéralement dans le dépôt à partir des données de comptage de grains. L’intégration des lois de décroissance massique exponentielle et puissance de chaque classe de constituant dans le dépôt permet d’estimer leur masse totale. Ces budgets massiques indiquent une magnitude~3,5 et une intensité ~9,2. La faible masse de ponces acides (<0.4 wt.%) exclus une origine par mélange de magma. Une proportion de ~98 wt.% et la faible densité de produits juvéniles révèle le caractère magmatique de l’éruption et l’absence d’interactions phréato-magmatiques. Les xénoclastes témoignent d’une fragmentation et d’une érosion des 2 km supérieurs du conduit. Des analyses morphologiques de particules menées avec un outil automatique et innovant (Morphologi G3 de Malvern) montrent le caractère hautement vésiculé des particules juvéniles et la faible viscosité de la lave. L’explosivité élevée d’août 2006 apparaît comme une manifestation extrême d’un système ouvert alimenté par des injections irrégulières de magma andésitique profond. L’activité du Tungurahua depuis 1999 définit un système caractérisé par un conduit très ouvert, une lave peu visqueuse et un dégazage par le biais d’explosions stromboliennes de faibles à hautes intensités. La méthode de détermination des budgets éruptifs est un atout majeur pour le suivi et la surveillance des phases éruptives en système ouvert. / Many andesitic volcanoes at subduction plate margins can experience in the course of their evolution periods of continuous eruption during years, decades, or centuries characterized by a fluctuation of the activity interrupted by explosive events of varying size and duration, with possible production of pyroclastic density currents. Magmatic activity lasts for long periods of time before violent explosive eruptions occur, which makes the forecasting of such events a real challenge. I focus on the case of Tungurahua, one of Ecuador’s most active volcanoes, which started an open-vent eruptive period in 1999. The paroxysmal phase occurred in August 2006 and resulted in a sustained eruption column associated with pyroclastic flows and surges. From the study of the tephra fall deposit, the aims of this work are to understand the origin and the dynamics of the August 2006 explosive paroxysmal phase and to develop a transposable method of high-resolution analysis of eruptive mass budgets. Based on a new grainsize deconvolution algorithm, two subpopulations of grains were distinguished, characterized and quantified in the bimodal distributions of the tephra fall deposit. These subpopulations result from the syn-deposition of coarse grains from the main volcanic plume and fine-grained ash elutriated from pyroclastic flows. A bulk minimum tephra volume ~42×106 m3 and a column height of 16-18 km above the vent are assessed. These data support a VEI 3 event of subplinian type. Detailed componentry counting and particle density analyses allow to propose a sigmoidal law to describe the particle density variations with grainsize of vesicular grains. This law is used to calculate the mass per unit area of the componentry classes laterally in the deposit, from the results of the componentry analyses. Integrating the mass decay rates of the componentries in the deposit, we infer their total mass. Results point to a mass magnitude of~3.5 and an intensity of ~9.2. The pumice mass fraction is far too small (< 0.4 %) to account for the high explosivity of the 2006 event. The high juvenile content in the deposit (~98 wt.%)supports a magmatic origin of the eruption, and no phreatic influence on the overall explosivity. The nature and content of non-magmatic material imply that fragmentation and erosional behaviour occurred in the upper ~2 km of the plumbing system. Morphological analyses performed with Morphologi G3 instrument (Malvern) show a high vesicularity of the products and a low viscosity of the lava. These results support an explosive event fed by a deep gas-rich andesitic reinjection, which would have incorporated a pocket of older differentiated magma and eroded the upper conduit during the sub-plinian event. Tungurahua activity describes a eruptive system characterized by an open-vent, a low lava viscosity and a degassing behaviour through strombolian explosions of weak to high intensity. The high-resolution mass-based approach reveals useful to decipher the origin of the violent 2006 paroxysm and has potential to improve magnitude determinations of ancient eruption by considering componentry mass instead of volume. It is also applicable for monitoring purposes in the context of on-going crises at many andesitic eruptive worldwide.

A qualitative description of the personal armour design system is elicited by comparing armour throughout the ages. Inputs that 'shape' designs are the materials technology, threat, wearer, task and environment. The emergent properties of protection, ergonomic effectiveness and financial cost form the basis of trade-offs to select final solutions. Work on the protection subsystem refines the key positive emergent property of personal armour. Existing quantifications of protection effectiveness are rejected in favour of a novel measure named the Usefulness Factor, UF. This is the first measure that accounts for the real benefit of armour. A five-stage model is proposed for the assessment of protection. Two feedback loops - due to making tasks as safe as possible and the ergonomic penalty of armour are evident. These must be considered in order to assess protection correctly. Casualty reduction analysis software (CASPER) is used to produce 'approach plots' and 'zones of usefulness' in order to make tasks safer and map the benefit of armour. This approach is demonstrated with the UK's Lightweight Combat EOD Suit against L2A2 and No. 36 Mills grenades, an HB876 area denial mine, a BL 755 sub-munition and a 105mm artillery shell. Assessment of secondary fragmentation from antipersonnel (AP) blast mines defines a threat input that is specific to Explosive Ordnance Disposal (EOD). Trials are carried out with explosive charges of 50g to 500g, buried under 5 or 10cm of stones and sand at a range of 1m. The threat is defined in terms of the probabilities of (a) being hit, (b) a hit perforating armour and (c) a hit incapacitating an unarmoured person. The chances of being hit close to the ground decrease to approximately 15% of the value when directly above the mine. Secondary fragmentation is not likely to perforate armour that protects against primary fragments. However, it is likely to incapacitate an unarmoured person. Protection is traded-off against proxies for ergonomic and financial cost effectiveness by using quantitative optimisation of personal armour. This introduces the concept of a 'protection optimisation envelope', which defines the bounds of possibility rather than a single solution. CASPER is adapted to produce weight and cost as well as incapacitation parameters. This provides a model that generates both benefits and constraints of armour. Hence, the foundations are laid for the world's first fully integrated personal armour design tools. The ergonomic effectiveness subsystem is the primary constraint of personal armour. Visor demisting for the UK's Mk 5 EOD Suit provides a simple example. Existing methods of assessment of the ergonomic penalty of armour are considered. A novel development of biomechanics computational models is proposed to predict both the mechanical and thermal burdens of armour.

The one of the dog use scope is explosive substances and booby traps searching. At present, when very often terrorist attacks or threats appear this usage is more and more often. To use the dog for this purpose means the dog has to be trained by means of complex training. In my thesis I have described the basic dog training and another training focused to special activities as the searching of explosive materials and mines is. I did not describe the all dogs basic exercises which the dog must handle safely because this theme is very extensive but only such excercise which I consider as important for explosive materials searching in practises. I have used available literature about dogs training and excercise, expert editorials and guidelines, my own experience with police dogs training and skilled knowledge from workshops and seminar meetings. I have created complex overview the dog preparing and the way of dog training for this special use. I have compared some methods for dogs training and way of excercise used in USA. By means of dogs special training and by means of their use we prevent extraordinary events and we preserve the human life doubtless. The thesis corresponds with another authors similar theses.

A qualitative description of the personal armour design system is elicited by comparing armour throughout the ages. Inputs that 'shape' designs are the materials technology, threat, wearer, task and environment. The emergent properties of protection, ergonomic effectiveness and financial cost form the basis of trade-offs to select final solutions. Work on the protection subsystem refines the key positive emergent property of personal armour. Existing quantifications of protection effectiveness are rejected in favour of a novel measure named the Usefulness Factor, UF. This is the first measure that accounts for the real benefit of armour. A five-stage model is proposed for the assessment of protection. Two feedback loops - due to making tasks as safe as possible and the ergonomic penalty of armour are evident. These must be considered in order to assess protection correctly. Casualty reduction analysis software (CASPER) is used to produce 'approach plots' and 'zones of usefulness' in order to make tasks safer and map the benefit of armour. This approach is demonstrated with the UK's Lightweight Combat EOD Suit against L2A2 and No. 36 Mills grenades, an HB876 area denial mine, a BL 755 sub-munition and a 105mm artillery shell. Assessment of secondary fragmentation from antipersonnel (AP) blast mines defines a threat input that is specific to Explosive Ordnance Disposal (EOD). Trials are carried out with explosive charges of 50g to 500g, buried under 5 or 10cm of stones and sand at a range of 1m. The threat is defined in terms of the probabilities of (a) being hit, (b) a hit perforating armour and (c) a hit incapacitating an unarmoured person. The chances of being hit close to the ground decrease to approximately 15% of the value when directly above the mine. Secondary fragmentation is not likely to perforate armour that protects against primary fragments. However, it is likely to incapacitate an unarmoured person. Protection is traded-off against proxies for ergonomic and financial cost effectiveness by using quantitative optimisation of personal armour. This introduces the concept of a 'protection optimisation envelope', which defines the bounds of possibility rather than a single solution. CASPER is adapted to produce weight and cost as well as incapacitation parameters. This provides a model that generates both benefits and constraints of armour. Hence, the foundations are laid for the world's first fully integrated personal armour design tools. The ergonomic effectiveness subsystem is the primary constraint of personal armour. Visor demisting for the UK's Mk 5 EOD Suit provides a simple example. Existing methods of assessment of the ergonomic penalty of armour are considered. A novel development of biomechanics computational models is proposed to predict both the mechanical and thermal burdens of armour.