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Chemical and Dynamical Characteristics of Stratosphere-Troposphere ExchangeHomeyer, Cameron Ross 2012 August 1900 (has links)
Stratosphere-troposphere exchange processes are responsible for controlling the distribution of chemically and radiatively important trace gases in the upper troposphere and lower stratosphere. Extensive characterization of exchange processes is critical to the development of our understanding and prediction of the climate system. This study examines the occurrence and dynamical and chemical characteristics related to two primary stratosphere-troposphere exchange processes: Rossby wavebreaking and moist convection.
Intrusions of air from the tropical upper troposphere into the extratropical stratosphere above the subtropical jet via Rossby wavebreaking potentially have a significant impact on the composition of the lowermost stratosphere (the stratospheric part of the "middleworld"). We first present an analysis of tropospheric intrusion events observed in aircraft observations using kinematic and chemical diagnostics. The transport processes operating during each event are discussed using high-resolution model analyses and backward trajectory calculations. In situ chemical observations of the tropospheric intrusions are used to estimate the mixing timescales of the observed intrusions through use of a simple box model and trace species with different photo-chemical lifetimes. We estimate that the timescale for an intrusion to mix with the background stratospheric air is 5 to 6 days. Detailed analysis of small-scale features with tropospheric characteristics observed in the stratosphere suggests frequent irreversible transport associated with tropospheric intrusions. We also present a 30-year climatology (1981-2010) of anticyclonically and cyclonically sheared Rossby wave-breaking events along the boundary of the tropics in the 350-500 K potential temperature range from ECMWF ERA-Interim reanalyses. Lagrangian transport analyses show poleward transport at altitudes below and above the 370-390 K layer. Poleward transport at lower levels is in disagreement with previous studies and is shown to be largely dependent on the choice of tropical boundary. In addition, transport analyses reveal three modes of transport for anticyclonic wavebreaking events near the tropical tropopause (380 K): poleward, equatorward, and bidirectional. These transport modes are associated with distinct characteristics in the geometry of the mean flow.
Stratospheric intrusions (tropopause folds) are known to be major contributors to stratosphere-troposphere exchange. The specific mixing processes that lead to irreversible exchange between stratospheric intrusions and the surrounding troposphere, however, are not entirely understood. This study presents direct observations of moist convection penetrating into stratospheric intrusions. The characteristics of convective injection are shown by using in situ aircraft measurements, radar reflectivities, and model analyses. Convective injection is observed at altitudes up to 5 km above the bottom of a stratospheric intrusion. Aircraft measurements show that convective injection in stratospheric intrusions can be uniquely identified by coincident observations of water vapor greater than about 100 ppmv and ozone greater than about 125 ppbv. Trajectory analyses show that convective injection can impact transport in both directions: from troposphere to stratosphere and from stratosphere to troposphere. We present a conceptual model of the synoptic meteorological conditions conducive to convective injection in stratospheric intrusions. In particular, convective injection is found to be associated with a "split front" where the upper-level frontal boundary outruns the surface cold front.
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Life Science Boundary Spanners and Their Role in Exchange Processes with AcademiaNilsson, Stefan Kristoffer, Widding, Peter January 2009 (has links)
<p>Innovation and entrepreneurship are recognized by many scholars as two of the key factors in company, regional and ultimately national growth. Up until now scholars have focused on macro level research leading to theories such as different innovation systems which explain how society through legislation and other incentives can facilitate the collaboration process between e.g. industry and academy leading to innovation. Despite this interest in the innovation process little effort has been made to elucidate how collaboration and innovation occurs from an individual perspective. This process involves individuals that interact in a knowledge exchange process.</p><p>Boundary spanners have been identified as facilitators and drivers of innovative processes between organizations. Their extensive networks enable them to distinguish collaboration opportunities and win-win situations with outside partners. In most industries boundary spanners are quite uncommon but within the life science sector many employees are potential boundary spanners since they often have an academic background and thus a good network with a major collaboration partner. We decided to look into the life science industry in order to investigate the exchange process in innovation collaborations and the role of academic background among boundary spanners. The research question that has guided this thesis was set to;</p><p>what prominent exchange customs exist among these boundary spanners and what does the background of these individuals have for these exchanges?</p><p>To be able to answer our research question and fulfill our aim we have made a qualitative hermeneutical study. By using a pending approach between deduction and induction we have continuously created understanding during the process of our theoretical and empirical generation. By performing five in-depth interviews with representatives from three different life science organizations we investigated how collaboration processes with academia are built and what role academic background can have for the boundary spanners involved.</p><p>From our empirical findings we derived answers to meet our aim;"identify prominent exchange customs among boundary spanners in innovation processes between academic and industry partners."</p><p>Exchange customs were dependent on foremost networking procedures or procedures indirectly dependent in networks. The actions of searching, screening and signalling were found to be central in the innovation process and for exchange customs. Furthermore we answered two set of sub-purposes;(i) what role does academic background have for the development of exchange customs and procedures pursued by boundary spanners in industry?</p><p>and(ii) how can background knowledge of academia contribute to or mitigate exchanges between boundary spanners in industry and academia?</p><p>The role of academic background was found to contribute significantly to all network dependent activities such as the above mentioned exchange customs. Moreover, we identified the process of academic self contact, i.e. when academia approaches industry with ideas, which could be a direct effect from signalling processes or personal networks. Background knowledge about academia affects exchange customs since it creates a better understanding of the academic partners' needs.</p><p> </p>
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Life Science Boundary Spanners and Their Role in Exchange Processes with AcademiaNilsson, Stefan Kristoffer, Widding, Peter January 2009 (has links)
Innovation and entrepreneurship are recognized by many scholars as two of the key factors in company, regional and ultimately national growth. Up until now scholars have focused on macro level research leading to theories such as different innovation systems which explain how society through legislation and other incentives can facilitate the collaboration process between e.g. industry and academy leading to innovation. Despite this interest in the innovation process little effort has been made to elucidate how collaboration and innovation occurs from an individual perspective. This process involves individuals that interact in a knowledge exchange process. Boundary spanners have been identified as facilitators and drivers of innovative processes between organizations. Their extensive networks enable them to distinguish collaboration opportunities and win-win situations with outside partners. In most industries boundary spanners are quite uncommon but within the life science sector many employees are potential boundary spanners since they often have an academic background and thus a good network with a major collaboration partner. We decided to look into the life science industry in order to investigate the exchange process in innovation collaborations and the role of academic background among boundary spanners. The research question that has guided this thesis was set to; what prominent exchange customs exist among these boundary spanners and what does the background of these individuals have for these exchanges? To be able to answer our research question and fulfill our aim we have made a qualitative hermeneutical study. By using a pending approach between deduction and induction we have continuously created understanding during the process of our theoretical and empirical generation. By performing five in-depth interviews with representatives from three different life science organizations we investigated how collaboration processes with academia are built and what role academic background can have for the boundary spanners involved. From our empirical findings we derived answers to meet our aim;"identify prominent exchange customs among boundary spanners in innovation processes between academic and industry partners." Exchange customs were dependent on foremost networking procedures or procedures indirectly dependent in networks. The actions of searching, screening and signalling were found to be central in the innovation process and for exchange customs. Furthermore we answered two set of sub-purposes;(i) what role does academic background have for the development of exchange customs and procedures pursued by boundary spanners in industry? and(ii) how can background knowledge of academia contribute to or mitigate exchanges between boundary spanners in industry and academia? The role of academic background was found to contribute significantly to all network dependent activities such as the above mentioned exchange customs. Moreover, we identified the process of academic self contact, i.e. when academia approaches industry with ideas, which could be a direct effect from signalling processes or personal networks. Background knowledge about academia affects exchange customs since it creates a better understanding of the academic partners' needs.
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Procesné riadenie komoditnej burzy / Process management of commodity exchangeScholtz, Ľudovít January 2009 (has links)
Thesis contains description of processes at Commodity Exchange Bratislava, analysis of current state of the processes, and recommends improvements of them for the future use. The main objective is to analyze if the current processes described in the exchange rules are optimal, and in the case they are not, the objective is to recommend the improvements. On behalf of hypothesis "By the application of the model of the process management it is possible to make the functions of the exchange more effective by optimizing the exchange rules, improving of the information systems, or removing of redundant activities." is possible to determine the state of effectiveness of processes. Value added by the thesis is in determining the state of the CEB exchange rules, and making improvements of them. Thesis is divided into chapters according to the conceptual logic of the processes. At the beginning is defined the key process. In next chapters is description of different types of orders, parameters, pairing process, and finally settlement of the contracts.
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Exchange processes between littoral and pelagic waters in a stratified lakeMarti, Clelia Luisa January 2004 (has links)
[Truncated abstract] The lake boundaries are an important source of sediment, nutrients and chemicals. For life inside the lake, the exchange between the lake boundaries (littoral) and lake interior (pelagic) is of central importance to Limnology as the net flux of nutrients into the water column is both the driving force and limiting factor for most algae blooms found during the stratification period. Consequently, the understanding of the relevant processes defining such an exchange is a further step toward a sound basis for future decisions by lake managers in order to ensure high water quality. The objective of this research was to investigate the physical processes responsible for the exchange of water and particles between the lake boundaries and the lake interior. An integrated approach using field experiments and 3D modelling as applied to Lake Kinneret (Israel) is presented. The field data revealed large-scale metalimnion oscillations with amplitudes up to 10 m in response to westerly diurnal winds, the existence of a well-defined suspended particle intrusion into the metalimnion of the lake, characterized by high concentrations of organic matter, and a well-mixed benthic boundary layer (BBL). The changes in the thermal structure explained the observed vertical and horizontal movements of the suspended particle intrusion. The horizontal advective transport via the metalimnion, associated with the velocities induced by the basin-scale mode-two Poincare wave, controlled the exchange between the lake boundaries and lake interior on daily time scales. The observed BBL over the lake slope varied markedly with time and space. Detailed comparison of simulation results with field data revealed that the model captured the lake hydrodynamics for time scales from hours to days. The model could then be used to extract the residual motions in the various regions of the lake. The residual motions below the surface layer were predominantly forced by the basin-scale internal wave motions, but the residual motion in the surface layer was found to be very sensitive to the curl of the wind field. The residual circulation was responsible for redistributing mass throughout the lake basin on time scales from days to weeks. A clear connection of dynamics of the BBL with the large-scale features of the flow was addressed. The time history of the mixing in the BBL and the resulting cross-shore flux was shown to vary with the phase of the basin-scale internal waves.
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Výměny náboje mezi projektilem a terčem v režimu nízkých energií studované pomocí HS-LEIS / Charge Exchange processes involved in projectile-target interaction at low energy range studied by HS-LEISBábík, Pavel January 2018 (has links)
This diploma thesis is focused on the charge exchange processes between projectile and target studied by the Low Energy Ion Scattering (LEIS) technique. Basic premise to investigate charge exchange processes is correct cleaning processes and proper settings of experimental instrument Qtac 100 placed in the Central European Institute of Technology (CEITEC) in Brno. Ion fraction expresses neutralization rate of the projectile. The parametr is investigated for clean and oxidized polycrystalline copper. Oxygen presence performs a significant part of reionization of backscattered neutralized projectiles.
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