"The primary purpose of this research was to quantify fire suppression and fire intensification phenomena for water spray application to high flash point hydrocarbon oil pool fires. Test data and analyses of the phenomena include the drop size distribution and application and delivered densities of various water sprays, and spray-induced oil cooling and oil splattering for mineral seal oil and for cooking oil 30-cm diameter pool fires. Four different types of tests were conducted as described below. A Dantec Particle Dynamic, phase Doppler, Analyzer was used to measure the water drop sizes and velocities generated by 13 selected nozzles and sprinkler heads. Most measurements were made 0.91 m (3 ft) below the nozzles/sprinklers, since this was the location of the center of the hydrocarbon pool in later fire tests. The correlations for the volume-median drop diameter, dw, were of the form , where D is the nozzle orifice and is the spray Weber number based on D and the nozzle velocity. A ring burner was designed and constructed for uniformly heating oil pool surfaces from above and igniting them. The resulting oil temperatures while the oil was heated to its flash point satisfied the one-dimensional transient heat conduction model for a semi-infinitely thick solid with a shallow heated layer near the surface. Water sprays actuated when the oil surface temperature reached its flash point rapidly cooled the heated layer and caused mixing with the cooler oil below. Fire suppression tests were conducted to determine the relationship between required water spray density, drop size, and oil temperature in order to achieve suppression. A data correlation using non-dimensional parameters was developed to quantify the fire suppression criteria for the high flash point oil fires. Oil pool fires with the higher flash point oils, such as the 291oC flash point soybean oil, could be suppressed with much lower water densities than those of the lower flash point (137oC) mineral seal oil. However, if the water spray drop sizes are sufficiently small, the lower flash point oil fires can also be extinguished with lower spray densities. The NFPA 15 specified critical water density (0.30 gpm/ft2, 12 mm/min) to extinguish high flash point pool fires is only valid for mineral seal oil when the drop size is lower than about 300 µm. It is valid with larger drop sprays only when the flash point of the oil is higher than 190 according to the correlation developed here. Spray-induced pool fire intensification tests were conducted under a fire products calorimeter for measuring heat release rates. Supplemental oil vaporization rate tests were also conducted to determine the contributions of oil vaporization and oil splattering to the intensified fire. Results showed that vaporization could only account for between 1% and 1.7% of the heat release rate in intensified mineral seal oil fires, and less than 1% of the heat release rate in intensified soybean oil fires. The remainder is due to spray-induced oil splattering, which increased with increasing drop Weber number as well as increased oil temperature. The heat release rate is enhanced by factor from 2.12 to 5.55 compared to the heat release rate of free burning cooking oil. For mineral seal oil, this ratio is in the range 0.92 to 1.25 for the spray conditions tested. Correlations with the dimensionless factors of and the Weber number of the water spray were also developed to quantify the ratio of the splattered oil to applied spray density."

While community ecologists have traditionally focused on local-scale processes, it has become apparent that a broader perspective, which explores the community-level ramifications of material fluxes within and between ecosystems, is necessary to effectively evaluate bottom-up influences on community structure and dynamics. In this dissertation, I employed ecosystem principles to understand these processes in rocky intertidal communities. I specifically examined the roles of sessile invertebrates in mediating the transfers and transformations of carbon and nitrogen in intertidal ecosystems. First, I quantified the links between nearshore pelagic and rocky intertidal systems. By assimilating suspended particulate organic material (seston), mussels and other sessile invertebrates serve as mediators of material exchange from pelagic to benthic ecosystems. I evaluated these trophic linkages along productivity gradients on the coasts of New Zealand and Oregon, which allowed me to address the influences of seston quality and quantity on the growth and ammonium excretion rates of mussels. My results highlight the necessity of simultaneously considering both seston quantity (total organic particulates) and quality (phytoplankton availability) in evaluating benthic-pelagic coupling. Second, I assessed the utilization of invertebrate-excreted ammonium by macroalgae in high-intertidal pools. Sessile invertebrates not only serve as mediators of material transfer into intertidal ecosystems, they also chemically transform that material, converting particulate organic nitrogen, which is unusable by macroalgae, into ammonium, which algae readily assimilate. l showed that especially in high-zone pools, which are isolated from the ocean for 80% of the time, invertebrate-excreted ammonium is an important nitrogen source for macroalgae. Ammonium accumulated in tide pools and was subsequently taken up by algae. This novel positive interaction influenced community structure: macroalgal species richness increased with the rate of invertebrate-mediated ammonium loading in pools. Finally, by experimentally manipulating macroalgae and invertebrates in laboratory mesocosms, I quantified the effect of ammonium loading on algal growth. I demonstrated that algal nitrogen assimilation rates increased with the rate of ammonium accumulation in tide pools, which resulted in enhanced growth when invertebrates were present. Together, these studies suggest that by merging community and ecosystem perspectives we can gain unique and important insights into the bottom-up processes influencing intertidal systems. / Graduation date: 2004

Synaptic transmission alters the strength of the postsynaptic potential, through a process called short-term synaptic plasticity (STP). In this study, endplate potentials (EPPs) from the frog neuromuscular junction were used to resolve and quantify the presynaptic components involved in enhancement and depression of transmitter release during repetitive stimulation under normal quantal release conditions (2 mM Ca2+, 1mM Mg2+). During trains of stimulation given between 10 - 200 Hz, the amplitude of the EPPs first increased then decreased; a maximum increase of 77% was produced after 2-4 stimuli. EPP amplitudes began to increase at ~ 20 Hz, were maximal at ~ 55 Hz, and thereafter, decreased as the rate of stimulation increased. The integrated total release after 25 stimuli was little changed across frequencies between 10 - 100 Hz. EPPs ran down in two phases: a fast phase, attributed to the depletion of a readily releasable pool (RRP) of synaptic vesicles, followed by a slow phase, attributed to the depletion of vesicles from a depot pool (DP). Depletion of the readily releasable pool of synaptic vesicles (RRP) was determined by quantifying release under the fast and slow time rundowns and subtracting the number of vesicles associated with mobilization to the RRP from the total number of vesicles released during stimulation trains of 50 impulses. Impulses were delivered at 12 different rates ranging from 50 to 200 /s. Estimates of the number of vesicles released from the RRP increased with frequency of stimulation until maximal depletion levels of 5500 - 6000 vesicles were reached at stimulation rates between 90-130/s, assuming a control quantal content of 200 vesicles released per impulse. Depletion was less at lower frequencies when the number of stimuli delivered was identical. When the RRP maximally depleted, release was inversely related to stimulation rate, as would be expected if mobilization from the depot pool was the sole determinate of release during the slow phase. An equation constructed from four known components of enhancement and two components of depression - the depletion of vesicles from a readily releasable pool (RRP) and from the depot pool (DP) that refills the RRP, was used to fit and then simulate EPPs obtained during trains using different patterns of stimulation and varying amounts of extracellular Ca2+; the decay time constant parameters of enhancement, numerically derived from the observed data, were fixed at tau ~ 46, 220, 1600, and 20000 ms. The number of components of enhancement necessary to approximate the data decreased, from four in low (0.14 - 0.2mM) extracellular Ca2+, to one (tau ~ 46 ms) in 2.0 mM extracellular Ca2+, but four components of enhancement were necessary to fit the data when the amplitude of the EPP was not depressed below the control amplitude. This model was able to predict within ~ 3 % EPP amplitudes over a 10-fold range of frequency and Ca2+ concentration.

No description available.

Production of electric energy is continuously affected by many factors. Therefore, tools for predicting the future production are needed. In turn, the production affects the electric energy price, which is set on electric energy exchanges. This thesis is intended to find out if the software SDDP can be used for hydrothermal power production simulations in the Nord pool area. By building a simplified model of the electric energy production in Sweden with a focus on hydro, thermal and wind power, the intention is to see how the model is affected by different conditions. The investigated conditions are several; higher and lower water inflows to the hydro power reservoirs; different amounts of installed wind power production; different price levels of emission allowances for CO2. By using the simulation software SDDP, more wind power was seen to lower the electric energy prices, as well as reduce the need of transmission of power from the northern to the southern parts of Sweden. In the simulation, Sweden was divided into four areas, connected where the main bottlenecks in the power grid are located. Water inflows to the reservoirs are crucial in the model. Actual inflow data can be bought from SMHI. However, due to the limited thesis budget, estimations were constructed instead. The estimations were difficult to make and turned out to be too high. Consequently, no reliable evaluation of the SDDP software could be done using this data.

Vernal pools are small, seasonally filling wetlands found throughout forests of north eastern North America. Vernal pools have been proposed as potential 'hot spots' of carbon cycling. A key component of the carbon cycle within vernal pools is the decomposition of leaf litter. I tested the hypothesis that leaf litter decomposition is more rapid within vernal pools than the adjacent upland. Leaf litter mass losses from litterbags incubated in situ within vernal pools and adjacent upland habitat were measured periodically over one year and then again after two years. The experiment was carried out at 24 separate vernal pools, over two replicate years. This is a novel degree of replication in studies of decomposition in temporary wetlands. Factors influencing decomposition, such as duration of flooding, water depth, pH, temperature, and dissolved oxygen were measured. Mass loss was greater within pools than adjacent upland after 6 months, equal after 12 months, and lower within pools than adjacent upland after 24 months. This evidence suggests that vernal pools of Central Ontario are 'hot spots' of decomposition up to 6 months, but not after 12 and 24 months. In the long term, vernal pools may reduce decomposition rates, compared to adjacent uplands.

Uppsatsens explorativa syfte är att utforska samt beskriva riskpremiens storlek och utveckling för de EPADs som handlas för olika elprisområden på den nordiska elmarknaden. Riskpremien har definierats enligt de prissättningsteorier som ursprungligen formulerats av Fama & French (1987) och beräknats ur ett ex post-perspektiv. Studien omfattar drygt 700 EPAD-kontrakt från perioden 2006 till 2014 Tillämpning av deskriptiv statistik visar existensen av betydande riskpremier vars tecken och storlek varierar mellan områden och tidsperioder. Detta är i linje med tidigare resultat av Kristiansen (2004) samt Marckhoff & Wimschulte (2009). Några långsiktiga trender har inte kunnat säkerställas statistiskt. Grafisk analys av säsongsmönster visar på låga (höga) riskpremier sommartid (vintertid) för samtliga områden utom Oslo där omvänt förhållande råder. Oslo samt de danska områdenas kontrakt handlas i contango, övriga områden i backwardation. Samtliga kontrakts riskpremier minskar dock över time-to-maturity, vilket stämmer överens med de riskpreferenser som beskrivs av Hillier et al., (2010). Resultaten från denna explorativa studie kan användas för att hitta intressanta perspektiv och frågeställningar till vidare forskning. Resultaten kan även vara av intresse dels för aktörer som använder EPADs för prissäkring och dels för de institutioner som verkar för en effektiv nordisk elmarknad, exempelvis NordREG, Energimarknadsinspektionen och Nord Pool. / This exploratory paper aims to describe the magnitude and development of risk premium in EPADs traded for different electricity price areas in the Nordic electricity market. Risk premium is defined according to the pricing theories originally formulated by Fama & French (1987), and calculated through an ex post perspective. The study includes more than 700 EPADs from 2006 to 2014. Application of descriptive statistics indicates existence of significant risk premia whose sign and magnitude varies between regions and time periods. This is in line with previous results by Kristiansen (2004) and Marckhoff & Wimschulte (2009). Any long-term trends have not been validated statistically. Graphical analysis of seasonal patterns revealed low (high) risk premium in summer (winter) for all areas except Oslo, where the seasonal patterns are the opposite. EPADs for Oslo and the Danish regions are traded in contango and all other areas in backwardation. Risk premia for all contracts do however approach zero when approaching maturity, which is consistent with theory of risk preferences described by Hillier et al., (2010). The results of this exploratory paper can be used to find interesting perspectives and research questions for further research. The results may also be of interest both for traders who are using EPADs for hedging purposes and the institutions aiming to achieve an efficient Nordic electricity market, such as NordREG, the Swedish Energy Markets Inspectorate and Nord Pool.

Stora koncerner med verksamhet i flera företag och inte sällan i flera länder kan gynnas av att styra hela koncernens ekonomi från en gemensam enhet. Moderbolaget har olika stor insyn i dotterbolagens verksamheter beroende på koncernens storlek och organisationsstruktur och därmed kan centralisering av likviditetsstyrningen ske på olika sätt. Syftet med uppsatsen är att ur ett ledarskapsperspektiv studera hur centraliserad likviditetsstyrning utförs samt hur det kan påverka koncerner. För att uppnå syftet har kvalitativa intervjuer genomförts med ekonomicheferna i fyra koncerner. Studien har därmed gjorts ur ett ledarskapsperspektiv och personliga intervjuer har gjorts för att få en djupare förståelse för hur koncernerna väljer att centralisera sin likviditetsstyrning samt vilken påverkan det har. Koncernerna som intervjuats har i hög grad centraliserad likviditetsstyrning och de viktigaste besluten fattas i huvudsak från en och samma enhet, resultatet av intervjuerna visar att centraliserad likviditetsstyrning skapar ökad översikt och kontroll. Ekonomicheferna anser sig ha god insyn i dotterbolagens verksamheter och kan därmed fatta de beslut som är de bästa för koncernen.  För att få en ökad förståelse för hur cash pooling kan användas som instrument för att centralisera likviditetsstyrningen intervjuades även två banker. Cash pooling ger en översiktlig bild över koncernens likviditet genom interna överföringar mellan konton med intern ränta. Därmed används det befintliga kapitalet på ett effektivt sätt innan externa lån behöver tas. Tre av koncernerna använder sig av cash pooling och de anser att det skapar en överskådlighet över koncernens likviditet samt en ökad effektivitet eftersom antalet externa banklån reduceras. Bankerna är eniga och menar att cash pooling skapar en samlad bild över koncernens likviditet. Utöver cash pooling tar studien även upp begrepp som centralisering, cash management och treasury management, vilka även de kan ses som sätt att effektivisera likviditetsstyrningen i en koncern. / Business groups with companies active in several countries can benefit from managing the entire group’s economy from one single entity. The parent company’s transparency of its subsidiaries is depending on the size and the organizational structure of the concern. Therefore, centralization of the liquidity can be done in several ways. The purpose of the study aims to clarify how centralization of the liquidity can be performed and what consequences it gives the concern. The study has been conducted through the leaders’ perspectives of the business groups. Interviews have been carried out with the financial chiefs of four business groups, in order to get a deeper knowledge of how the liquidity is centralized and what effects it brings. The business groups have in a great extent centralized their liquidity to one entity where the most important decisions are made. The financial chiefs consider themselves to have the right knowledge to make decisions with the concern’s best interest in mind. To get a deeper knowledge about centralization of liquidity from the perspectives of the banks, and also to get awareness of cash pooling and how it is used, the decision of interviewing two banks as well, was made. Cash pooling is an instrument for optimizing the liquidity within business groups and thereby enabling an effective management of cash, and reducing the need for external borrowings. Three out of the four concerns interviewed are users of cash pooling and they all consider it an effective instrument that creates transparency and control over the liquidity. The banks agree and say that it gives a more composed picture of the liquidity of the concern, which simplifies the contact with the bank. In addition to cash pooling, the study also discusses cash management and treasury management. In conclusion, it is clear to say that there are considerable advantages, such as a greater transparency and control, when a corporate group is centralizing its liquidity. It also creates legitimacy against banks.

Malgré une surveillance constante exercée par les MNS, des noyades surviennent dans les PPAP. La thèse propose une analyse systémique et organisationnelle du risque de noyade dans ces équipements. Elle s'appuie sur une méthodologie qualitative plurielle : une analyse documentaire visant à quantifier le phénomène accidentel doublée de 9 entretiens d'experts (partie C), des observations de terrain menées dans 108 PPAP dans l'optique d'objectiver l'effectivité de la surveillance (partie D) et des entretiens semi-directifs afin de cerner les causes profondes des inadéquations : (n=27) à titre expérimental au sein d'une métropole du Grand-Ouest à l'occasion d'une mission d'expertise commanditée et (n=30) au sein de la communauté d'agglomération Caen la mer (partie E). Les résultats obtenus montrent que : 1) la production de données quantitatives sur la noyade en PPAP est entravée par un certain nombre de barrières faisant de cette question un « angle mort » de la connaissance ; 2) la surveillance exercée par les MNS est dégradée la moitié du temps d'observation et que 3) les arbitrages managériaux, la dynamique organisationnelle, mais aussi les représentations des acteurs interfèrent avec la fonction de surveillance, exerçant une influence sur sa réalisation et sa qualité. Les travaux mettent en évidence la coexistence et la redondance de boucles de rétroaction relativement efficaces mais peu coordonnées, articulées de manière contingente et inscrites dans différents registres. Aléatoire quant à son efficacité, la surveillance exercée par les MNS renvoie à une tâche difficile, fortement contrainte et de surcroît sujette à des formes plurielles d'adaptation. Ce travail montre que la gestion des risques dans ces équipements ainsi que les pratiques actuelles sont perfectibles. A ce propos, des recommandations à même d'optimiser la gestion des risques et la surveillance des bassins ont pu être formulées. Des actions préventives ont du reste été engagées (partie F) / Drownings occur in PSP (public swimming pool) despite lifeguard supervision.The thesis proposes a systemic and organizational analysis of the drowning risk in PSP based on a combined qualitative methodology : a documentary analysis aimed at quantifying the accidental phenomenon coupled with 9 expert interviews (part C), field observations conducted in 108 PSP in order to objectifying the effectiveness of supervision (part D) and semi-structured interviews to identify the root causes of mismatches : (n = 27) in experimental way for a Grand-Ouest metropolis within the framework of an expertise mission and (n = 30) within the Caen la mer community (part E). The results of the study show that : (1) the production of quantitative data on PSP drowning is hampered by several barriers that make this issue a “blind spot” of the knowledge ; 2) the supervision by lifeguard is degraded half of the observation time and 3) managerial arbitration, organizational dynamics, but also social representations of the actors interfere with the supervision function, exerting influence on its realization and quality. The work highlights the coexistence and redundancy of feedback loops that are relatively efficient but not coordinated, articulated in a contingent way and included into different registers. Monitoring by lifeguards, which is random about its effectiveness, refers to a difficult task, which is highly constrained and, moreover, subject to plural forms of adaptation. This work shows that the management of the drowning risks in these equipment and the current practices are perfectible. Moreover, recommendations were formulated to optimize risk management and pool supervision. Preventive action was also launched (Part F)

Les estuaires, situés à l’interface entre les domaines continental et marin, constituent des zones essentielles dans les échanges de matières. Ils jouent dès lors un rôle capital pour les cycles biogéochimiques et biologiques et subissent, par ailleurs, des pressions climatiques et anthropiques croissantes depuis plusieurs décennies. Le présent travail a été focalisé sur les peuplements benthiques et pélagiques présents dans la partie fluviale (Garonne et Dordogne) de l’estuaire de la Gironde, zone àtrès faible salinité où ces peuplements n’avaient encore jamais été étudiés. Alors que la méiofaune, composée principalement de Nématodes, s’est avérée relativement abondante dans les domaines intertidal et subtidal, le macrobenthos est apparu composé essentiellement d’Oligochètes en intertidal et complètement absent en subtidal. La grande plasticité du copépode dominant Eurytemora affinis a été confirmée, celui-ci occupant une niche écologique différente dans la partie fluviale de l’estuaire par rapport à la zone haline. L’importance de la température plutôt que la qualité du pool nutritif sur la productivité d’E. affinis a été démontrée, mettant en évidence une fois de plus la grande adaptabilité de cette espèce dans un habitat très fluctuant. L’étude de l’habitat benthique et pélagique, notamment en terme de qualité du pool nutritif disponible pour les organismes, a démontré que la contribution de la matière organique réfractaire d’origine terrestre est dominante. La contribution du micro phytobenthos à la composition de la matière organique sédimentaire et pélagique a aussi été mise en évidence. Enfin,l’étude des communautés planctoniques dans la partie fluviale de l’estuaire de la Gironde a montré que l’espèce E. affinis y occupe une position clef. / Being at the interface between continental and marine systems, estuaries are essential areas for matter exchanges. Therefore, they play a crucial role in biological and biogeochemical cycles. In addition to natural fluctuations, these systems have also undergone increasing climate and anthropogenic pressures for several decades. The present work focused on the benthic and pelagic assemblages in the fluvial section (Garonne and Dordogne rivers) of the Gironde estuary, a low salinity area where these communities had never been studied. Meiofauna, mainly composed ofnematodes, was found in relatively high abundance in both intertidal and subtidal zones.Macrozoobenthos was essentially composed of oligochaetes in the intertidal, while it was totally absent in the subtidal areas. The high plasticity of the dominant copepod Eurytemora affinis was confirmed, with a different ecological niche in the freshwater section of the estuary compared to the haline area downstream. The importance of temperature rather than the quality of the nutrient pool on the productivity of E. affinis was demonstrated, thereby confirming the great adaptability of thisspecies to a highly fluctuating habitat. Study of benthic and pelagic habitat, especially in terms of quality of the nutrient pool available to the organisms, showed that the contribution of refractoryorganic matter with a terrestrial origin is dominant. A significant contribution of microphytobenthos to the composition of sedimentary and pelagic organic matter was also highlighted. Finally, the study of planktonic communities in the fluvial part of the Gironde estuary showed that the species E. affinis occupies a key position in this part of the estuary.