Dissertations / Theses on the topic 'Emission pathways'

Orientadora: Profa. Dra. Karina Passalacqua Morelli Frin<br>Dissertação (mestrado) - Universidade Federal do ABC, Programa de Pós-Graduação em Ciência & Tecnologia - Química, 2014.<br>Neste trabalho, foram estudadas as propriedades fotofisicas de alguns compostos de coordenacao de renio(I), fac-[Re(CO)3(NN)L]0/+1 (NN = 2,2f-bipiridina ou 2,2f-bipirimidina; L = Cloreto (Cl-), piridina (py), 2-aminometilpiridina (ampy) ou 2-fenilpiridina (phpy), e [Cl(CO)3Re(bpm)Re(CO)3Cl]. Os compostos sintetizados foram caracterizados quanto as suas propriedades na espectroscopia de ressonancia magnetica nuclear de 1H (1H RMN), absorcao e emissao na regiao do Ultravioleta- Visivel (UV-Vis) e espectroscopia na regiao do Infravermelho (IV). Os espectros eletronicos de absorcao na regiao de UV-Vis evidenciaram que os compostos sintetizados apresentaram altos valores na absortividade molar (na ordem de 104 L.mol-1.cm-1) e exibiram na regiao analisada transicoes intraligante (1IL¿Î¨¿Î*) do ligante polipiridinico e do ligante piridinico e transicoes de transferencia de carga metal-ligante (1MLCTRe¨NN). Para o composto binuclear de renio(I), [Cl(CO)3Re(bpm)Re(CO)3Cl], observou-se uma prolongamento da banda de absorcao, isto e, o composto absorve radiacao visivel ate aproximadamente 600 nm.. Os espectros de emissao dos compostos fac-[Re(CO)3(bpy)L]0/+1 (L = Cl, py, ampy ou phpy) apresentaram uma banda larga e nao estruturada, sendo que o estado excitado 3MLCTRe¨bpy e o responsavel pela emissao. O composto fac-[Re(CO)3(bpy)Cl] apresentou em diclorometano (CH2Cl2) uma emissao maxima em 612 nm e 0,005 de rendimento quantico, enquanto que os compostos fac-[Re(CO)3(bpy)L]+1 (py, ampy ou phpy) apresentaram a emissao em 548, 558, 526 nm e rendimento quantico de 0,216, 0,078, 0,254, respectivamente. Portanto, a substituicao do ligante cloro pelo ligante piridinico provoca um deslocamento hipsocromico da emissao e tambem a um aumento. no rendimento quantico, tendo em vista que o ligante cloro reduz a eficiencia do cruzamento intersistema. Os compostos fac-[Re(CO)3(bpm)Cl] e [Cl(CO)3Re(bpm)Re(CO)3Cl] apresentaram uma emissao relativamente baixa em diferentes solventes, na ordem de 10-4. Enquanto que o estado responsavel pela emissao do composto mononuclear e 3MLCTRe¨bpm, por outro lado quando ocorre a coordenacao com outro atomo de renio, [Cl(CO)3Re(bpm)Re(CO)3Cl], existe a desestabilizacao deste estado, tendo assim, o estado excitado 3ILbpm responsavel pela emissao. O estado excitado de mais baixa energia 3MLCT para os compostos fac-[Re(CO)3(bpm)Cl] e fac-[Re(CO)3(bpy)L]+, (L= py, ampy ou phpy) e os diferentes valores observados em meios rigidos confirmaram a sensibilidade do estado excitado a rigidez do meio, observou-se o efeito rigidocromico. Consequentemente, estes compostos podem ser utilizados no desenvolvimento de dispositivos moleculares.<br>In this work, it were studied the photophysical properties of some coordination compounds of rhenium(I), fac-[Re(CO)3(NN)L]0/+1 (NN = 2,2'- bipyridine, bpy, or 2,2'-bipyrimidine, bpm; L = chloride (Cl), pyridine (py), 2-aminomethylpyridine (ampy) or 2 -phenylpyridine (phpy), and [Cl(CO)3Re(bpm)Re(CO)3Cl]]. The synthesized compounds were characterized by nuclear magnetic resonance spectroscopy of 1H (1H NMR), absorption and emission in the Ultraviolet- Visible region (UV - VIS) and spectroscopy in infrared region (IR). The electronic absorption spectra in the UV-Vis region showed that the synthesized compounds presented high molar absorptivity (in the order of 104 L.mol-1.cm-1) and exhibited in the analyzed region intraligand transitions (1IL¿Î¨¿Î*) of the polypyridyl ligant and pyridine, as well as metal to ligand charge transfer transitions (1MLCTRe ¨ NN). For binuclear compound of rhenium(I), [Cl(CO)3Re(bpm)Re(CO)3Cl], there was a prolongation of the absorption band, i.e., the compound absorbs visible radiation up to approximately 600 nm.The emissions spectra of the compounds fac-[Re(CO)3(bpy)L]0/+1(L = Cl-, py, ampy or phpy) exhibited a broad and unstructured band assigned to the lowest lying excited state, 3MLCTRe ¨ bpy. The compound fac-[Re(CO)3(bpy)Cl] presented in dichloromethane (CH2Cl2) a maximum emission at 612 nm and quantum yield of 0.005, while the compounds fac-[Re(CO)3(bpy)L]+1 (py, ampy or phpy) presented the emission in 548, 558, 526 nm and quantum yield of 0.216, 0.078, 0.254, respectively. Therefore, the substitution of the chloride ligant by pyridine causes a hypsochromic shift in the emission, as well as an increase in the quantum yield, since the chloride ligant reduces the efficiency of intersystem crossing. The fac-[Re(CO)3(bpm)Cl] and [Cl(CO)3Re(bpm)Re(CO)3Cl] compounds presented a relatively low emission in CH3CN, in the order of 10-4. While the 3MLCTRe ¨ bpm was the responsible for the mononuclear emission, when the coordination to an another atom of rhenium occurred [Cl(CO)3Re(bpm)Re(CO)3Cl], this state was destabilized, and thus, the 3ILbpm excited state became the responsible to emission. The state excited of lower energy 3MLCT for compounds fac-[Re(CO)3(bpm)Cl], fac-[Re(CO)3(bpy)L]+ (L = py, ampy or phpy) and the different values observed in rigid media have confirmed the sensitivity of the excited state to the medium rigidity, due to the rigidochromic effect. Consequently, these compounds can be used in the development of molecular devices.

Transportation and energy play an essential role in modern society. Since the Industrial Revolution, fossil fuels have enabled great advancements in human society. Within this process, Internal Combustion Engines Vehicles (ICEVs) played a significant role in guaranteeing reliable and affordable long-distance transportation. However, the subsequent increase of the Motorized Private Transport resulted in undesired effects such as pollution. One instrument in reducing the Greenhouse Gas (GHG) emissions of the transport sector is to shift from the conventional ICEVs toward zero local emission vehicles. Electric Vehicles (EVs) are being promoted worldwide as a suitable powertrain technology that could replace the ICEVs. However, unless combined with electricity from renewable generation technologies the EVs will not effectively reduce GHG emissions. Through the simulation of future transport and energy sector scenarios in Germany, the GHG emission reductions have been analyzed. Techno-economic and environmental characteristics for several powertrain technologies under several vehicles charging strategies are evaluated. The thesis explores the impact of charging EVs on the electrical grid. The result show that EVs using smart charging strategies that support Vehicle-to-grid (V2G) are capable of fulfilling mobility needs of users while providing substantial flexibility to the electrical grid. Such flexibility can facilitate the future expansion of non-dispatchable Renewable Energy Sources (RES).

We are entering a golden age for radio astronomy. There are several new interferometers upcoming, whose characteristics, in terms of sensitivity, frequency coverage, angular and temporal resolution, field of view, will permit unprecedented deep observations. The most outstanding ones among them will be the Square Kilometre Array (SKA) and its precursors, such as the Australian SKA Pathfinder (ASKAP) and MeerKAT. Several surveys will be carried out, in continuum and spectral line. In particular we will have as continuum surveys the Evolutionary Map of the Universe (EMU), to be carried out with ASKAP, the MeerKAT International GigaHertz Tiered extra-galactic Exploration Survey (MIGHTEE) and the MeerKAT High Frequency Galactic Plane Survey (Meer-GAL), both to be carried out with MeerKAT. All this surveys will observe large regions of the sky at high sensitivity, providing a huge increase in known object. This thesis focuses on radio stars and the science that can be carried out with the new radio interferometers. Even if, in general, stars emit in radio a small fraction of their luminosity, at these wavelengths it is possible to trace different phenomena that is not possible to study by other means. Furthermore the Galaxy is optically thin in radio, then we can observe stars in the GP that we could not observe in the optical frequencies. Unfortunately, due to the faintness of stars in radio, the number of currently known radio stars is limited to a small sample. Furthermore, they have all been observed directly, not discovered in a blind survey. We want to know how many radio stars to expect from the new surveys and, to do that, we worked on two different approaches. In the theoretical approach, described in Chapter 3 of the thesis, we estimate the number of stars that belong to those spectral type that incorporates radio emitting classes, such as Magnetic Chemically Peculiar (MCP) stars, OB stars, Flare stars and RS CVn stars from the Besancon model (Robin et al., 2003), and, from this information, from the probability of a certain spectral type star to be a radio emitter, we estimate the total number of stars detected at different sensitivities. As reported in the conclusions, we expect about 250 000 stars in EMU and about 50 000 000 with SKA-1. For the observational approach, we started the Stellar Continuum Originating from Radio Physics In Ourgalaxy (SCORPIO). SCORPIO is a blind survey of a five square degree region of the Galactic Plane, carried out with ATCA at 2.1 GHz and designed with two major goals, a scientific and a technical one. First of all, we wanted to know how may stars per square degree we can detect in a blind survey and to collect as much information as possible about the radio emission. Secondly, we wanted to know how to address the issues that comes from a blind survey on a area of the Galactic Plane, such as issues due to the complex structures present in the GP; issues due to the presence of variable sources; issues due to the diffuse emission that dominate the GP; issues regarding the identification of different populations. The work on the SCORPIO project is described in Chapters 4, 5 and 6 of this thesis. In Chapter 4 we focused on the data reduction, analysing each step from the raw data to the final image. In Chapter 5 we described a way to discriminate the source classes, studying their emission mechanism through their spectral indices. We found out, comparing our work to the ATLAS survey, that, in the SCORPIO field, about 20 sources per square degree with a flux density greater than 1 mJy are Galactic. In Chapter 6 we show all the different images created during the process, showing their importance in the study of specific physical properties. We also described the H ii regions and the radio stars found in the field. On Chapter 7 we do a summary and present the results accomplished in the thesis and the planned future work.

Introdução: A partir de sua descrição anatômica, o interesse sobre a ação das vias auditivas eferentes sobre a audição vem crescendo progressivamente, com estudos realizados em animais e humanos. A função do trato olivococlear medial em humanos pode ser avaliada por meio da supressão das emissões otoacústicas, exame clínico que se mostra promissor para a análise do estado coclear e dos mecanismos auditivos centrais, auxiliando no diagnóstico de lesões e disfunções retrococleares. O estudo sobre a supressão das emissões otoacústicas com apresentação de estímulo supressor contralateral ou bilateral torna-se útil para avaliar a interação entre as orelhas e contribuir para a investigação da ação do sistema eferente. Objetivo: Os objetivos do presente estudo foram: a) comparar o efeito da estimulação unilateral e bilateral na pesquisa dos níveis de resposta das emissões otoacústicas por estímulo transiente (EOAT) e por produto de distorção (EOAPD) em indivíduos com audição normal; b) comparar o efeito de supressão bilateral e contralateral das EOAT. Metodologia: Esta pesquisa foi realizada no Laboratório de Investigação Fonoaudiológica em Audição Humana do Departamento de Fisioterapia, Fonoaudiologia e Terapia Ocupacional da Faculdade de Medicina da Universidade de São Paulo. A casuística foi composta por 30 sujeitos com audição dentro dos parâmetros da normalidade, de acordo com a avaliação audiológica convencional, sendo 15 do gênero masculino e 15 do feminino, na faixa etária de 18 a 33 anos. Foi realizada a pesquisa das EOAT e EOAPD em ambas as orelhas, inicialmente com estimulação unilateral e posteriormente com estimulação bilateral (estímulo eliciador fornecido simultaneamente para ambas as orelhas). Em seguida realizou-se a pesquisa da supressão das EOAT com estímulo supressor contralateral. Foi utilizado o Analisador de Emissões cocleares Echoport ILO 292 USB II, versão 6, Otodynamics. Resultados: Observou-se que os valores de nível de resposta da coleta com estimulação unilateral foram significantemente maiores do que os valores da coleta com estimulação bilateral, tanto para EOAT como para EOAPD, evidenciando a redução do nível de resposta das emissões otoacústicas com a apresentação do estímulo eliciador bilateral. Não foi observado efeito de gênero e de lado de orelha tanto para as respostas de EOAT como de EOAPD. Para EOAT, comparando-se o valor da supressão bilateral com a supressão contralateral, observaram-se maiores valores de supressão com a estimulação acústica bilateral. Conclusão: A coleta das EOA com estimulação bilateral foi capaz de ativar mecanismos do sistema auditivo eferente e produziu um efeito supressor em relação à coleta unilateral. A supressão bilateral das EOAT observada apresentou maior magnitude em relação à supressão contralateral convencionalmente utilizada.<br>Introduction: Since the anatomical description of olivocochlear pathway, the interest on its action over the hearing has been growing progressively supported by studies performed in animals and humans. The function of medial olivocochlear pathway in humans can be assessed through the otoacoustic emissions suppression, a clinical examination which is useful for the analysis of cochlear state and central auditory mechanisms, aiding in the diagnosis of hearing injuries and disorders. The study about otoacoustic emissions suppression with presentation of contralateral or bilateral suppressor stimulus becomes useful to assess the interaction between the ears and contribute to research the auditory efferent system action. Aim: The main goal of this study was to compare the effect of unilateral and bilateral stimulation in response of transient evoked otoacoustic emissions (TEOAE) and distortion product evoked otoacoustic emissions (DPOAE) in individuals with normal hearing. The secondary purpose was to compare the effect of bilateral and contralateral transient evoked otoacoustic emissions suppression. Method: This study was developed in the Human Hearing Investigation Laboratory of the Physical Therapy, Speech and Hearing Science and Occupational Therapy Department of the Medicine College of São Paulo University, Brazil. Data were obtained from 30 adults (15 males and 15 females) with normal hearing, according to conventional audiological evaluation. Their age ranged from 18 to 33 years. The research of TEOAE and DPOAE was conducted in both ears, initially only with unilateral stimulation and later with bilateral stimulation (elicitor stimulus provided simultaneously to both ears). Then was performed the search of contralateral transient evoked otoacoustic suppression. It was used an Echoport ILO 292 USB II, version 6, Otodynamics. Results: The response levels of bilateral TEOAE and DPOAE were significantly larger than the response of unilateral search. So, it was observed a reduction in the response level of otoacoustic emissions with the presentation of bilateral elicitor stimulus. No significant differences in TEOAE and DPOAE responses were found among gender and ear side. For TEOAE, comparing the amount of bilateral and contralateral suppression, was found higher values in the first testing paradigm. Conclusion: The bilateral EOA search was capable of activating mechanisms of the auditory efferent system and produced a suppressive effect in comparison with unilateral EOA search. Bilateral TEOAE suppression showed a greater suppression effect than contralateral TEOAE suppression.

Thesis advisor: Christopher Maxwell<br>Reducing carbon dioxide emissions and strengthening the economies of developing countries are among the most pressing issues within Sustainable Development. In order to enact effective policies to move toward Sustainable Development Goals, a deep understanding of the pollution-income relationship, and how it differs between developed and developing countries, is imperative. Using advanced panel data analysis techniques, and using the IPAT and EKC models, my results find that the relationship between carbon dioxide emissions and economic development differs for developed and developing countries. Additionally, my analysis uses carbon dioxide emissions, a global pollutant, to proxy environmental quality. My results, however, oppose those of existing literature which use local pollutants as the proxy. This may suggest that the utility gained from reducing local pollutants differs from the utility gained by reducing global pollutants. Further exploration of the differing pollution-income relationship for local and global pollutants serves as an area for future research<br>Thesis (BA) — Boston College, 2021<br>Submitted to: Boston College. College of Arts and Sciences<br>Discipline: Departmental Honors<br>Discipline: Economics

This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.<br>Thesis: S.M. in Technology and Policy, Massachusetts Institute of Technology, School of Engineering, Institute for Data, Systems, and Society, 2019<br>Cataloged from student-submitted PDF of thesis.<br>Includes bibliographical references (pages 104-109).<br>The Indian government is aiming to reduce carbon emissions intensity in the power sector through incentivizing the addition of renewables sources into the grid. India has set the goal that at least 40% of total power capacity must be non-fossil fuel-based by 2030 with more ambitious goals expected to be set for 2040 and 2050. To meet the decarbonization goals by the next decades, the central government is promoting a large-scale development of wind turbines and solar photovoltaic power plants. Achieving long-term decarbonization in the Indian power sector presents several challenges to the current electric grid. For example, the current generation mix relies heavily on coal power plants such that integrating solar and wind plants (i.e., variable renewable energy (VRE) sources) adds several layers of economic and technical complexity. Other challenges include improving the national quality of service and reducing local emissions.<br>The overall effect is amplified by India's rapidly increasing electricity consumption, which has necessitated the build-out of additional capacity to meet the future load. The following thesis analyzes potential pathways to the decarbonization of India's grid by 2037. The study explores 24 different scenarios, each considering different technology costs (solar, wind, and storage), setting different gas prices, and defining different emissions limits. The analysis uses the capacity expansion model "GenX" developed internally at MIT. GenX is a deterministic capacity expansion planning model. The model optimizes generation, storage, and transmission capacity expansion decisions and dispatch of generation and storage resources on an hourly basis to meet the electricity demand in a year, at the lowest cost possible.<br>The study successfully identifies the trade-offs between system costs, global emissions, and local emissions levels for different scenarios, enabling the assessment of the long-term impact of large infrastructure decisions in the electric power sector. Of the findings: (1) Scenarios without emission limits, continue to be dominated by coal and emissions rose relative to 2017 levels. (2) Scenarios with emissions limits had an increased share of VRE sources, greater than 50% in some scenarios. (3) Some scenarios with high VRE penetration required significant dispatchable capacity that could ramp up suddenly to meet net load, reaching 270 GW in peak load days. (4) Gas-based plants competed directly with storage technologies; both technologies are flexible and can adapt to abrupt changes in VRE generation. However, as storage costs rise, gas plants begin to dominate the generation mix.<br>There are some challenges in developing new gas plants, as plants cycling increase and the gas fleet is underutilized in some scenarios. The thesis also addresses the policy implications for each scenario. To reduce greenhouse gasses emissions, setting emissions limits can be hard to enforce. Imposing a carbon tax is ideal, although it is hard to set the right price. Setting a non-fossil fuel portfolio standard can not necessarily help reduce emissions to a specific target. Many regulatory changes are required to encourage higher levels of VRE penetration such as promoting better coordination between state and regional system operators, reducing uncertainty in the use of the gas infrastructure, and promoting the development of storage technologies.<br>by Iván Rudnick García.<br>S.M. in Technology and Policy<br>S.M.inTechnologyandPolicy Massachusetts Institute of Technology, School of Engineering, Institute for Data, Systems, and Society

Success or failure of climate policies in limiting warming to beneath particular thresholds depends on several physical, economic and social uncertainties. Whilst scenario analysis can be informative as to the types of policies that are required to achieve these goals, the complexity of scenario analysis often masks the underlying fundamental choices. This dissertation introduces the concept of the ‘decarbonization identity' to simply and systematically describe the mutually exclusive and collectively exhaustive range of choices available in future climate policy decisions. The simple identity states that the remaining carbon budget [B] for a given level of warming can be partitioned into four areas: the already committed 'baked-in' emissions from existing capital stock [E]; new commitments arising from investments in additional capital stock yet to be made [N]; less the stranding of existing or future capital stock [S]; and the additional atmospheric space created by negative emissions technologies (NETs) [A]. This dissertation finds that currently operating electricity generators [E] would already emit more CO2 (~300 GtCO₂) then is compatible with currently available generation-only carbon budgets [B] for a temperature rise of 1.5-2°C (~240 GtCO₂). In addition, the current pipeline of planned fossil fuel power plants would add almost the same amount [N] of emission commitments (~270 GtCO₂) to this capital stock again. Finally, these carbon budgets are inherently uncertain and depend on future, yet to be achieved, reductions of short-lived climate pollutant (SLCP) emissions. Should those reductions not be achieved today's remaining carbon budgets could be up to 37% smaller. Policymakers have now five choices to achieve the Paris climate goals: (1) protect and enhance carbon budgets by early and decisive action on SLCPs; (2) retrofit existing power generators with carbon capture and storage (3) ensure that no new polluting capital stock is added; (4) strand a considerable amount of global electricity generation capacity; and (5) create additional atmospheric space by scaling up NETs. Over the coming years and decades, the challenge will be to identify the most efficient balance of these options.

A utilização das emissões otoacústicas (EOs) têm contribuído na avaliação do sistema auditivo eferente por meio do estudo do efeito da estimulação acústica simultânea à pesquisa das EOs, descrito na literatura como supressão das EOs. Este trabalho teve por objetivo comparar o efeito da estimulação contralateral do ruído na amplitude das emissões otoacústicas evocadas por clique (EOE-c), em crianças que apresentam audição normal e em crianças com Neuropatia Auditiva/Dessincronia Auditiva. A casuística foi constituída de 16 crianças com audição normal e 11 crianças com o diagnóstico audiológico de Neuropatia Auditiva/Dessincronia Auditiva. As EOE-c foram pesquisadas, utilizando-se o clique linear na intensidade de 60 dB NPS e, para a estimulação contralateral do ruído, foi utilizado o ruído branco na intensidade de 65 dB NPS, com monitoramento do nível de pressão sonora, gerado no conduto auditivo externo, por meio do microfone sonda. Os resultados demonstraram que, nas crianças com audição normal, além da redução da amplitude das EOE-c, foi observada supressão das EOE-c, ou seja, a ausência do registro das EOE-c com a estimulação contralateral do ruído. Nas crianças com Neuropatia Auditiva/Dessincronia Auditiva, foi observado que a estimulação contralateral do ruído não provocou mudanças significativas na amplitude das EOE-c. Este trabalho permitiu concluir que a amplitude das EOE-c do grupo de crianças com audição normal se comportou de maneira estatisticamente diferente do grupo de crianças com Neuropatia Auditiva/Dessincronia Auditiva na presença da estimulação contralateral do ruído, e que a média da redução da amplitude das EOE-c frente à estimulação contralateral do ruído nas crianças com audição normal é estatisticamente maior que a redução da amplitude das EOEc nas crianças com Neuropatia Auditiva/Dessincronia Auditiva.<br>The use of otoacoustic emissions (EOs) has contributed to the evaluation of the efferent auditory system through the effect of the acoustic stimulation simultaneous to the EOs, described in the literature as EOs suppression. This study had the objective of comparing the effect of the contralateral stimulation of the noise in the amplitude of the click-evoked otoacoustic emissions (EOE-c), in children having normal hearing and in children with Auditory Neuropathy/ Auditory Dsy-synchrony. The casuistry was constituted by 16 children having normal hearing and 11 children diagnosed audiologically as having Auditory Neuropathy/ Auditory Dsy-synchrony. The EOE-c were scrutinized by using the linear click in the intensity of 60 dB SPL, and to the contralateral noise stimulation, the white noise was employed in the intensity of 65 dB SPL, with the monitoring of the level of sound pressure generated in the external auditory conduit, by using the microphone probe. The results have shown that in children with normal hearing, besides the reduction of amplitude of the EOE-c, it was noticed their suppression, that is, the absence of the record of the EOE-c with the contralateral noise stimulation. It was observed that the contralateral noise stimulation havent provoked significative change in the amplitude of the EOE-c in children with Auditory Neuropathy/ Auditory Dsy-synchrony. This study allowed us to conclude that the amplitude of EOE-c in children with normal hearing presented a different statistical result in the group of children with Auditory Neuropathy/ Auditory Dsy-synchrony in the presence of the contralateral noise stimulation and the average of the amplitude reduction of the EOE-c in the face of children with normal hearing is statistically higher than the amplitude reduction of the EOE-c in the children with Auditory Neuropathy/Auditory Dsy-synchrony.

Characterized by excessive myocardial glycogen deposition, cardiac hypertrophy, frequent cardiac arrhythmias and progressive conduction system disease, the PRKAG2 cardiac syndrome stems from a genetic mutation in the γ2-subunit of AMP-activated protein kinase (AMPK). Although functionally diverse, the main role of AMPK is to modulate cardiac metabolism in response to depleted ATP levels. A comprehensive study of the dysfunctional regulation of AMPK activity involved in the progression of the human PRKAG2 cardiac syndrome is hindered by the limitations of in vitro techniques. Positron emission tomography (PET) imaging with the glucose analogue, FDG, offers a quantitative assessment of myocardial glucose uptake non-invasively. The aim of this thesis was to determine the ability of FDG to detect changes in glucose uptake, storage and metabolism in the heart in relation to AMPK activity and provide insights into the mechanism of PRKAG2 cardiac hypertrophy. To achieve this aim, a transgenic AMPK γ2-subunit Arg302Gln mouse model was evaluated with small animal FDG PET with correlation to biochemical assays of cardiac AMPK activity and the glycogen metabolism pathway. Using the vena cava blood input function, FDG myocardial glucose uptake was reliably assessed in mice for the first time with Patlak modeling. Reduced FDG uptake in the Arg302Gln PRKAG2 mouse model suggested a feedback pathway reducing exogenous glucose uptake due to excessive intracellular glycogen stores. Despite an increase in FDG uptake in the skeletal muscle of the PRKAG2 mutant mice following insulin stimulation, there was no change in cardiac uptake, signifying myocardial insulin resistance. Increased reliance on glucose oxidation by TMZ inhibition of fatty acid oxidation reduced glycogen stores, restored cardiac function and eliminated ventricular preexcitation. The observed reduction in mouse myocardial FDG uptake mirrors the reduction previously observed in the human PRKAG2 patients. The potential now exists to evaluate both progression and therapeutic interventions for the PRKAG2 cardiac syndrome with the transgenic mouse model with translation to the affected patients using FDG cardiac imaging.

This report reviews the current state of long-term climate action planning in 17 cities which have publicly communicated carbon reducttargets in line with the IPCC recommended 80% reduction by 2050 (80x50) for stabilizing the impacts of climate change at 2°C.  The aim of this report is to provide a foundation of support for cities in achieving their deep carbon reduction goals through a comprehensive understanding of leading climate action plans and the context under which they were created, including current city emissions and demographic data, climate plan reduction strategies and targets, and feedback on plan creation and needs from city planning staff.  By achieving this aim, cities are in a better position to understand where their plans fit in the global context and connect with other cities around common issues, research institutions have a new benchmark analysis of leading action plans to build further research upon, and city-level climate action organizations have a clearer idea of how to focus efforts in helping cities achieve carbon reduction goals.  This aim is achieved through the application of a framework for comparing city plans and targets, an analysis of current city emissions and demographic data, and synthesis of key findings from city planning staff discussions.   Key findings show no clear demographic and environmental biases exist within these 17 cities, indicating long-term climate action planning can be undertaken by cities across the full spectrum of size, climate, and current per capita emissions output, though regional geographic and development bias exists.  Plans for carbon reduction are highly concentrated among a small number of actions, indicating the movement has coalesced around a standard set of strategies for achieving deep carbon reductions.  Finally, the relative newness of plans, with the majority less than 5 years old, and the lack of commonality among cities in emissions methodology and communication of reduction strategies, shifts a short-term focus towards standardization methodologies which enable deeper comparison between cities and plans.

<p> In California and many places around the world, exhaust from heavy-duty (HD) diesel vehicles accounts for a major fraction of criteria pollutant emissions such as particulate matter (PM) and nitrogen oxides (NOx), and HD vehicles are a significant consumer of petroleum-based fuels and a growing contributor to greenhouse gas (GHG) emissions. California has been a leader in implementing a broad range of policy measures that promote the development and deployment of fuels and technologies to reduce fuel consumption and emissions from HD vehicles. This dissertation formulates an analytical method to investigate the costs and benefits of various technology pathways for HD vehicles that result in drastic reductions in criteria pollutant and GHG emissions. </p><p> Though there are several studies that estimate the fuel use and emissions contribution of HD vehicles in California and the implications of accelerated advanced technology adoption over time, no studies investigate both the end-user and externality cost impacts of these sweeping technology changes to the HD fleet. This dissertation begins to fill this research gap. Taken together, private and external costs represent an approximation of total societal costs, which is used in a cost-benefit framework to explore the impact of various scenarios for introducing advanced fuel and technologies in the HD vehicle fleet out to 2050. The primary objective of this research is to examine the comparative emissions, fuel use, and total societal costs of six discrete technology adoption scenarios for California HD vehicles between 2010 and 2050. </p><p> The results indicate that, compared to the Baseline, the five remaining scenarios provide net present value (NPV) savings between roughly 5% and 10% and significant reductions in emissions and fuel use. Total costs are dominated by vehicle retail, fuel, and maintenance expenses, and monetized externalities generally account for less than 5% of total costs. Compared to the Baseline, reduced petroleum-based fuel use makes up roughly 90% or more of the cost savings for each of the non-Baseline scenarios. </p><p> For the HD fleet, reaching an 80% reduction in GHG emissions versus 1990 levels by 2050 requires that vehicle sales shift almost completely to zero tailpipe emission technologies by 2030, annual fuel consumption reductions in new vehicles are between 2% and 4% per year, and fuel feedstocks transition to low-carbon pathways. Results from this research suggest that if California is to dramatically transform the HD vehicle fleet over such a short timeframe, a combination of strong incentive programs and technology-forcing regulations are required.</p>

O trato olivococlear medial realiza o controle eferente das células ciliadas externas, regulando as contrações lentas e atenuando as contrações rápidas. Com o surgimento das técnicas de pesquisa da amplitude das emissões otoacústicas sem e com estimulação acústica contra, ipsi ou bilateralmente, é possível estimar clinicamente as condições fisiológicas desse trato, uma vez que o efeito resultante de redução/supressão das emissões otoacústicas indica seu funcionamento efetivo. O envelhecimento implica em diminuição da atividade do sistema auditivo central, em função da degeneração das estruturas envolvidas nas habilidades auditivas. A perda de fibras axonais e a diminuição da bainha de mielina nas estruturas do trato representam perda da eficácia de sua função. O objetivo deste estudo foi investigar o efeito da idade na atividade do trato sobre as propriedades mecânicas da cóclea, por meio da análise da amplitude das emissões otoacústicas com estimulação acústica contralateral. A casuística foi composta por 75 indivíduos ouvintes, de ambos os sexos, agrupados conforme a idade. A metodologia para captação das emissões otoacústicas foi o modo convencional, com clique linear na intensidade de 60 dB NPS e o ruído branco, como estímulo contralateral, em 60 dB NPS. A análise dos resultados considerou o valor do response das orelhas e a comparação entre os grupos etários. Os resultados revelam diferenças estatisticamente significantes entre os valores do response das EO sem e com estimulação acústica contralateral, nos indivíduos de 20 a 39 anos. O efeito redução/supressão das EOE-T diminui substancialmente com a idade, por volta da quarta década. Conclui-se que o envelhecimento prejudica a efetividade da atividade do trato sobre a cóclea.<br>Medial olivocochlear tract makes the efferent control of the outer hair cells, controlling the slow contractions and mitigating rapid contractions. Upon the appearance of techniques for the investigation of the amplitude of otoacoustic emissions with and without acoustic stimulation against, ipsi and bilaterally, it is now possible to stimulate clinically the physiologic conditions of this tract, once the resulting effect of reduction/suppression of otoacoustic emissions indicates its effective action. Aging brings a decrease of the activity of central auditory system, as a function of the degeneration of structures involved in auditory abilities. The loss of axon fibers and the decrease of myelin sheath in tract structures causes the loss of efficacy in its function. It was the objective of this study to assess the effect of aging in tract activity upon mechanical properties of cochlea, through the analysis of the amplitude of acoustic emissions with a contralateral acoustic stimulation. Casuistic comprised 75 both sex hearing individuals, grouped according to age. Methodology to capture otoacoustic emissions employed conventional means, with a linear click at a 60 dB NPS intensity and white sound, as a contralateral stimulus, at 60 dB NPS. The analysis of results considered the value of the response of the ears and the comparison of between age groups. Results show statistically significant differences between values for response of EO with and without a contralateral acoustic stimulation, in individuals between 20 to 39 years of age. The reduction/suppression effect of EOE-T decreases greatly with aging, around the fourth decade. It is concluded that aging impairs the efficacy of the activity of tract upon the cochlea.

"Zero emissions, zero poverty" has become an ambitious target to fight climate change and reduce poverty at the same time. In Kenya, eradication of extreme poverty through economic growth is one of the aims to be achieved by the Government of Kenya by 2030. Historically, economic growth has been directly linked to increased emissions. Poverty eradication through economic growth is proving to be challenging due to the fact that both developed and developing countries are expected to mitigate climate change through emissions reduction. Despite the challenge, Kenya has prioritised low carbon development as a means to eradicate poverty and mitigate climate change. "Clean coal" is one of the low carbon developments that the country has proposed. This study investigates how "clean coal" can assist Kenya to remain low carbon and develop properly. The analysis of the literature and qualitative data consists of three parts: the first analysis establishes the relationship between emissions and poverty in Kenya. The second part of the analysis assesses the literature on cost, environmental, social and economic consequences of clean coal as a low carbon development. The third component analyses the discourse of the actors involved in the decision-making process to understand the controversy for and against clean coal in Kenya. The study finds that there is possibly a link between poverty and emissions in Kenya and that improved socio-economic development results in increased emissions. The study also suggested that efforts to develop may be hindered by the increasing rate of inequality. The discourse analysis highlighted that Lamu Coal Power Plant may lead to economic development through employment and economic growth.; which comes at a high cost on environmental degradation (increased emissions and pollution) and increased deprivations (negatively impacted livelihood, health deterioration and displacement) that are likely to result in increasing poverty.

INTRODUÇÃO: Uma possibilidade de pesquisa em audição é a supressão das emissões otoacústicas, que verifica a diminuição de sua magnitude a partir de estimulação acústica simultânea. Acredita-se que esta diminuição ocorra devido ao papel da via eferente auditiva. OBJETIVO: verificar a atividade do sistema auditivo eferente, por meio da supressão contralateral das emissões otoacústicas, em neonatos com e sem indicadores de risco para perda auditiva. MÉTODO: foram avaliados 21 neonatos com indicadores de risco para perda auditiva (grupo estudo) e 30 neonatos sem indicadores (grupo controle) por meio das emissões otoacústicas evocadas por estímulo de freqüência específica \"tone burst\" em 2000 e em 4000 hertz, na ausência e na presença de ruído branco contralateral. RESULTADOS: a orelha direita e o grupo controle apresentaram vantagem na amplitude das EOA TB. Os valores médios de \"Response\" para 2000 hertz foram 17,73 dB no grupo controle e 16,55 dB no grupo estudo, para o gênero feminino e 16,63 dB no grupo controle e 16,12 dB no grupo estudo, para o gênero masculino. Para 4000 hertz, os valores médios de \"Response\" foram 14,63 dB no grupo controle e 15,09 dB no grupo estudo, para o gênero feminino e 18,57 dB no grupo controle e 15,06 dB no grupo estudo, para o gênero masculino. Na supressão, houve vantagem da orelha direita, do grupo controle para o gênero feminino e do grupo estudo para o gênero masculino, embora sem plena significância estatística. Os valores médios de supressão para a variável \"Response\" em 2000 hertz foram 1,66 dB no grupo controle e 0,84 dB no grupo estudo, para o gênero feminino e 1,41 dB no grupo controle e 2,07 dB no grupo estudo, para o gênero masculino. Para 4000 hertz, os valores médios da supressão em \"Response\" foram 1,29 dB no grupo controle e 0,98 dB no grupo estudo, para o gênero feminino e 1,75 dB no grupo controle e 2,14 dB no grupo estudo, para o gênero masculino. CONCLUSÃO: A partir de estímulos de freqüência específica, em 2000 e em 4000 hertz, foi possível verificar o efeito inibitório da via eferente auditiva sobre a amplitude das EOA, em neonatos. A utilização de estímulos de freqüência específica pode contribuir para a avaliação da função auditiva periférica e central nesta população.<br>INTRODUCTION: A possible hearing research is the suppression of otoacoustic emissions which verifies a decrease of its magnitude from a simultaneous acoustic stimulation. It is assumed that this decrease occurs because of the role of the auditory efferent pathway. AIM: to verify the activity of the auditory efferent pathway by the contralateral suppression of OAE in neonates with and without risk factors for hearing loss. MEHOD: 21 neonates at risk for hearing loss (study group), and 30 neonates without risk factors for hearing loss (control group) were assessed through otoacoustic emissions evoked by a frequency specific stimulus, \"tone burst\", at 2000 and at 4000 hertz, with and without contralateral white noise. RESULTS: the right ear and the control group presented advantage in the amplitude of OAE TB. The mean values of \"Response\" at 2000 hertz were 17,73 dB in the control group and 16,55 dB in the study group, for female subjects, and 16,63 dB in the control group and 16,12 dB in the study group, for male subjects. At 4000 hertz, the mean values of \"Response\" were 14,63 dB in the control group and 15,09 dB in the study group, for female subjects and 18,57 dB in the control group and 15,06 dB in the study group, for male subjects. In the suppression, there was an advantage of the right ear, of the control group for female subjects, and of the study group for male subjects, although without statistical significance. The mean values of suppression for the variable \"Response\" at 2000 hertz were 1,66 dB in the control group and 0,84 dB in the study group, for female subjects, and 1,41 dB in the control group and 2,07 dB in the study group, for male subjects. At 4000 hertz, the mean values of suppression for \"Response\" were 1,29 dB in the control group and 0,98 dB in the study group, for female subjects, and 1,75 dB in the control group and 2,14 dB in the study group, for male subjects. CONCLUSION: From frequency-specific stimuli at 2000 and at 4000 hertz, it was possible to verify the inhibitory effect of the auditory efferent pathway upon the amplitude of otoacoustic emissions in neonates. The use of frequencyspecific stimuli may contribute for the assessment of the central auditory function in this population.

This paper provides an overview of developmental timetables relevant to hearing and of current pediatric audiological techniques and practices. The first sections summarize structural and functional development of the auditory pathway and the development of primary auditory processing. These developmental sequences appear to follow similar paths in humans and animals. Speech and music perception involve more complex processing and are strongly influenced by experience. Hearing disorders affect the perception of complex sounds in a variety of ways, depending on the site(s) of lesions. Early onset hearing impairment, including conductive loss from chronic otitis media, can seriously impede language development. Language cannot develop normally without adequate speech stimulation. Sensitive and inexpensive techniques are available for performing neonatal hearing screening, and early intervention has a positive effect on development of language skills in hearing-impaired children. Thus, the National Institute of Health has recommended nationwide universal newborns hearing screening. The rationale and methodology of universal screening programs is summarized in the chapter. Advances in the field of the genetics of hearing impairment are also reviewed Recent advances in the field of auditory physiology - coupled with longstanding concerns about delayed identification of hearing impairment - have precipitated public health initiatives (National Institute of Health, 1993) and legislation for neonatal hearing screening programs (Blake & Hall, 1990). Pediatric audiology, once more “art” than science, is now largely based on physiologic methods rather than observed behavior. With current techniques, it is not only possible to detect hearing impairment at birth but also to determine the site of the lesion and to obtain close estimates of hearing threshold at specific frequencies (Werner, Folsom, & Mancl, 1993). Habilitative measures, including amplification, can begin within weeks of birth. Protocols for the management of hearing impairment are guided not only by the site of the lesion but by the developmental sequences and interactions among all of the child’s sensory modalities. This chapter provides an overview of developmental timetables relevant to hearing and of current pediatric audiological techniques and practices.

Cette thèse présente une approche multidisciplinaire de la recherche sur la modélisation du changement climatique. Elle explore les limites du cadre actuel d'élaboration de scénarios prospectifs utilisé par le Groupe d'experts intergouvernemental sur l'évolution du climat (GIEC) et présente de nouvelles approches alternatives et complémentaires pour surmonter ces limites. À l'aide de Pathfinder, un modèle simple axé sur le climat et le cycle du carbone, on investit un espace inexploré par la gamme des modèles climatiques simples existants en incorporant les données les plus récentes et en inversant le processus usuel de génération des scénarios de changement climatique.Des perspectives d'amélioration de notre modèle sont ensuite identifiées en examinant la représentation de l'océan dans Pathfinder, en se concentrant sur le Nexus chaleur-carbone océanique et son rôle critique dans le cycle global du carbone et la réponse du climat aux émissions cumulées de CO2. Une comparaison est faite entre les représentations de l'interface carbone-chaleur océanique dans Pathfinder et les modèles du système terrestre les plus récents, mettant en évidence les divergences significatives et les implications potentielles pour les scénarios de réchauffement à venir.Après avoir présenté Pathfinder en détail, ma recherche examine tout d'abord les réductions d'émissions de CO2 physiquement nécessaires pour atteindre l'objectif de réchauffement global de 1,5C, en soulignant l'importance des émissions de CO2 provenant de l'utilisation des terres et du forçage non lié au CO2. Nous inversons ensuite la chaîne de causalité pour relier les impacts environnementaux aux activités anthropiques, ce qui constitue une approche unique. L'étude cartographie les espaces d'activités anthropiques compatibles avec certaines limites planétaires et introduit un cadre de modélisation qui tient compte du réchauffement climatique, de l'acidification des océans, de l'élévation du niveau de la mer et de la fonte de la banquise arctique.En outre, cette thèse examine le rôle des modèles d'évaluation intégrée dans la compréhension des coûts d'atténuation des émissions associés à ces scénarios climatiques. Elle explore l'impact des choix conceptuels dans ces modèles sur l'identification de scénarios d'atténuation robustes et examine les effets de l'incertitude physique et de l'équité intergénérationnelle.Ce manuscrit se termine par une appréciation des contributions clés de ma recherche doctorale à la modélisation du changement climatique, l'exploration de nouvelles frontières et opportunités dans le domaine, et de mon ressenti personnel sur le domaine de recherche. Dans l'ensemble, cette thèse représente une approche unique et innovante de la modélisation du changement climatique qui, je l'espère, fournira des outils pratiques pour l'évaluation et le développement de stratégies d'atténuation<br>This dissertation presents a multidisciplinary approach to climate change research. It explores the limitations of the current scenario-building framework used by the Intergovernmental Panel on Climate Change (IPCC) and presents new strategies for better understanding climate futures. Using Pathfinder, a simple model focused on climate and the carbon cycle, this research fills a gap in the range of existing simple climate models by incorporating the latest data and providing a backward, temperature-driven examination of climate change scenarios.Prospects for improvement are then identified by discussing the representation of the ocean in Pathfinder, focusing on the Ocean Heat-Carbon Nexus and its critical role in the global carbon cycle and the response of Earth's climate to cumulative CO2 emissions. A comparison is made between the representations of the Ocean Heat-Carbon Nexus in Pathfinder and state-of-the-art Earth system models, highlighting the significant discrepancies and potential implications for future warming scenarios.After introducing Pathfinder, my research first examines the CO2 emission reductions physically required to meet the 1.5C global warming target, emphasizing the importance of CO2 emissions from land use and non-CO2 forcing. We then reverse the causal chain to link environmental impacts to anthropogenic activities, which is a unique approach. The study maps the spaces of anthropogenic activities compatible with planetary boundaries and introduces a modeling framework that accounts for global warming, ocean acidification, sea level rise, and Arctic sea ice melt.Furthermore, this thesis examines the role of Integrated Assessment Models (IAMs) in understanding the costs associated with these climate scenarios. It explores the impact of conceptual choices in these models on the identification of robust mitigation pathways and examines the effects of physical uncertainty and intergenerational equity.This manuscript concludes with an appreciation of the key contributions of my doctoral research to climate change modeling, exploration of new frontiers and opportunities in the field, and personal insights into the research journey. Overall, this research represents a unique, innovative approach to climate change modeling that will hopefully provide practical tools for assessing and developing mitigation strategies

Thesis: S.M. in Atmospheric Science, Massachusetts Institute of Technology, Department of Earth, Atmospheric, and Planetary Sciences, 2014.<br>In title on title-page. double-underscored "x" appears as subscript. Cataloged from PDF version of thesis.<br>Includes bibliographical references (pages 42-49).<br>A 3-D chemical transport model with coupled oxidant-aerosol chemistry (GEOSChem) is used to analyze the influence of recent (2001 to 2010) growth in Asian NOx and Asian SO 2 emission on transpacific transport of Asian particulate matter, especially sulfate, by quantifying and analyzing the details of chemistry and its sequential influence on transpacific transport during spring and summer. From 2001 to 2010, the spring averaged Asian sulfate enhancement in the western US model surface layer increases by 0.01-0.03 [mu]g M-3 (about 4% of the surface sulfate concentration over the US at 2010 emission level). The net chemical production rate increases in the troposphere over Asia but decreases over the Pacific Ocean. The sulfate production pathway shifts toward gas phase production by OH (7-8% increase-China; 2-3% increase-Upper atmosphere Pacific Ocean) with corresponding reductions in aqueous phase production by H202 ; resulting in a switch of the most important production pathway from aqueous production by H202 to gas phase production by OH. Almost doubling the Asian NO. emission during the period has a negligible influence on Asian sulfate enhancement over the US; this change in Asian NOx emission causes the net chemical production rate to increase in the Asian boundary layer, but to decrease in the upper Asian atmosphere, and in the atmosphere over the Pacific Ocean and the US. This is because the Asian NOx emission growth strengthens the oxidizing power in the Asian boundary layer to more actively form sulfate (mostly removed by wet scavenging), reducing available SO2 for further production away from the source. The Asian NOx emission growth is the major driver in changing the sulfate production pathways toward the gas phase. The 20% increase in Asian SO 2 emission during the period is the primary driver in increasing Asian sulfate enhancement over the US; this change accelerates net sulfate production rate, and makes a minor contribution to shifting toward gas phase production by OH over the course of the transpacific transport. The calculated sulfate column burden shows a notable increase as a response to the changes in Asian emissions. However, the shifts in sulfate lifetime over China due to changes in Asian SO 2 and/or Asian NO, emission are almost negligible (generally 1-2%), and lifetimes over the upper level Pacific Ocean are generally reduced by 3-4%.<br>by Flora Min.<br>S.M. in Atmospheric Science

Com o objetivo de analisar o efeito de supressão das emissões otoacústicas transientes com a apresentação de ruído branco contralateral, foram avaliadas 51 crianças de 7 a 11 anos, sendo 15 sem queixas auditivas (grupo controle) e 36 com distúrbio de processamento auditivo (divididas em dois grupos experimentais). Foram determinados, para cada grupo, a média e o desvio padrão dos valores de supressão em cada condição de estímulo: clique linear e clique não linear. Verificou-se que a proporção de ausência do efeito de supressão foi significativamente maior nos grupos de crianças com distúrbio de processamento auditivo, comparados ao grupo controle<br>This study concerns the suppression of transient evoked otoacoustic emissions by contralateral white noise in children with auditory processing disorder. Fifty-one children between 7 and 11 years old were assessed, being 15 children without auditory complaints (control group) and 36 with auditory processing disorder (divided in two experimental groups). The mean suppression of otoacoustic emissions and standard deviation were determined for each group, both in linear and nonlinear acquisition mode. The results provided evidence that proportion of absence of otoacoustic emissions suppression was significantly higher in auditory processing disorder groups, when compared to control group

Climate change brings with it a set of challenges if our buildings are to remain thermally comfortable whilst energy consumption is kept to a minimum and greenhouse gas emissions are reduced. As a means of addressing these issues, three models have been constructed using future climate data as forecast by the UK Climate Projections (UKCP09), and they have been used to inform the Department of Energy and Climate Change (DECC) 2050 Calculator. Observing there to be a correlation between regionalised National Grid non-daily metered gas demand and daily air temperature, the first model uses these data and UKCP09 data to estimate future energy savings deriving from a reduced requirement for space heating across the built environment. Using UKCP09 data, the second model estimates the increase in the uptake of residential air-conditioning if the UK were to follow the same experience as Canada, regression data showing a correlation between penetration levels of air-conditioning in the residential sector and air temperature in North America. Resultant levels of space cooling energy consumption are calculated using two different bottom-up approaches, the first of which uses the dwelling as the base unit, and the second of which uses the air-conditioner. Deriving from conventional degree-day theory and substantiated through a series of building simulations, the third model uses a novel metric, the Adaptive Comfort Degree-Day, to estimate the energy savings potential of employing adaptive comfort standards for future climates using UKCP09 data. Finally, it is found that pathways prescribed as achieving an 80% reduction in emissions levels by 2050 remain successful when the DECC 2050 Calculator is updated with correctly-weighted air temperatures. However, the demand for space heating is under-estimated by up to 99 TWh when the Calculator is amended so as to take account of data from the preceding space heating model.

Le système auditif possède deux particularités. En périphérie, les mécanismes cochléaires actifs (MCA), sous-tendus par la motilité des cellules ciliées externes (CCE), interviennent dans la sensibilité auditive et la sélectivité fréquentielle. Sur le versant central, le système efférent olivocochléaire médian (SEOCM), qui se projette sur les CCE et module les MCA, améliore la perception auditive en milieu bruité. Sur le plan exploratoire, ces deux processus peuvent être évalués grâce aux otoémissions acoustiques provoquées (OEAP) et leur suppression controlatérale. Par ailleurs, des résultats expérimentaux chez l’animal ont montré l’existence d’un rétrocontrôle exercé par le système auditif corticofuge descendant (SACD) sur la cochlée, via le SEOCM.Le présent travail comporte trois études réalisées chez l’humain, visant à explorer les interactions entre SACD, SEOCM et MCA. Les études 1 et 2, utilisant une méthodologie innovante chez des patients épileptiques réalisant une stéréo-électroencéphalographie, ont révélé un effet atténuateur différentiel de la stimulation électrique intracérébrale sur l’amplitude des OEAP, en fonction des modalités de stimulation, ainsi qu’une variabilité de cet effet selon les caractéristiques de l’épilepsie. L’étude 3 a montré un renforcement bilatéral de l’activité du SEOCM chez des musiciens professionnels.Pris dans leur ensemble, ces résultats fournissent d’une part, des arguments directs et indirects en faveur de l’existence d’un SACD fonctionnel chez l’humain. D’autre part, des phénomènes de plasticité à long terme, pathologique ou supranormale, seraient susceptibles de modifier l’activité de cette voie cortico-olivocochléaire<br>The auditory system has two special features. At peripheral level, active cochlear micromechanisms (ACM), underlain by motility of outer hair cells (OHC), are involved in auditory sensitivity and frequency selectivity. At central level, the medial olivocochlear efferent system (MOCES), which directly projects onto OHC to modulate ACM, improves auditory perception in noise. From an exploratory point of view, both processes can be assessed through transient evoked otoacoustic emissions (TEOAE) and the procedure of contralateral suppression. In addition, experimental data in animals have disclosed a top-down control exerted by corticofugal descending auditory system (CDAS) on cochlea, via MOCES.The present work comprises three studies carried out in human, aiming to investigate interactions between CDAS, MOCES and ACM. The first and second studies, based on an innovative experimental procedure in epileptic patients undergoing presurgical stereoelectroencephalography, have revealed a differential attenuation effect of intracerebral electrical stimulation on TEOAE amplitude depending on stimulation modalities, as well as a variability of this effect depending on the clinical history of epilepsy. The third study has shown a bilateral enhancement of MOCES activity in professional musicians.Taking together, these results provide direct and indirect evidence for the existence of a functional CDAS in humans. Moreover, possible long-term plasticity phenomenon, either pathological –as in epileptic patients– or supernormal –as in professional musicians– may change cortico-olivocochlear activity

Radiative forcing by increased atmospheric levels of greenhouse gases (GHGs) produced by human activities could lead to strongly undesirable effects on oceans and their dependent human systems in the coming centuries. Such dangerous anthropogenic interference with the climate system is a possibility the UN Framework Convention on Climate Change (UNFCCC) calls on nations to avoid. Unacceptable consequences of such interference could include inundation of coastal areas and low-lying islands by rising sea level, the rate of which could exceed natural and human ability to adapt, and ocean acidification contributing to widespread disruption of marine and human food systems. Such consequences pose daunting socioeconomic costs, for developing nations in particular. Drawing on existing literature, we define example levels of acceptable global marine change in terms of global mean temperature rise, sea level rise and ocean acidification. A global-mean climate model (ACC2), is implemented in an optimizing environment, GAMS, and coupled to an economic model (DICE). Using cost-effectiveness analysis and the tolerable windows approach (TWA) allows for the computation of both economically optimal carbon dioxide emissions pathways as well as a range in carbon dioxide emissions (the so-called ``emissions corridor'') which respect the predetermined ceilings and take into account the socio-economically acceptable pace of emissions reductions. The German Advisory Council on Global Change (WBGU) has issued several guardrails focused on marine changes, of which we find the rate and absolute rise in global mean temperature to be the most restrictive (0.2 degrees Celsius per decade, 2 degrees Celsius total). Respecting these guardrails will require large reductions in both carbon and non-carbon GHGs over the next century, regardless of equilibrium climate sensitivity. WBGU sea level rise and rate of rise guardrails (1 meter absolute, 5 cm per decade) are substantially less restrictive, and respecting them does not require deviation from a business-as-usual path in the next couple hundred of years, provided common assumptions of Antarctic ice mass balance sensitivity are correct. The ocean acidification guardrail (0.2 unit decline relative to the pre-industrial value) is less restrictive than those for temperature, but does require emissions reductions into the coming century.

The increased use of synthetic nitrogen fertilizers since the early 1900s has resulted in greater food production but also problems with nitrogen pollution in freshwaters. Nitrate (NO3-) is a common pollutant in rivers and groundwater in agricultural watersheds; the drinking water limit in Canada is 10 mg N/L. Microbial processing of NO3- and ammonium (NH4+) can produce nitrous oxide (N2O), a potent greenhouse gas responsible for about 5% of the greenhouse effect. Rivers provide a complex environment, where a variety of redox conditions, available substrates and microbial populations can co-exist on small spatial and temporal scales. Therefore, many questions remain about N cycling in river environments. N2O is produced during anoxic microbial NO3- or NO2- reduction to N2 (denitrification) and oxic microbial NH4+ oxidation to NO3- (nitrification). A significant portion (~25%) of global anthropogenic N2O is produced in rivers and estuaries, but mechanisms are not clear and predictability is poor. The United Nations Intergovernmental Panel on Climate Change (IPCC) provides default equations for calculating N2O emission estimates, in which annual NO3- loading to rivers is positively linearly related to N2O emissions. However, it is unclear how sound these linear relationships are and if measured N2O emissions are similar to IPCC estimates. The Grand River watershed is the largest in southern Ontario. Nutrient discharge to the Grand River is high due to extensive agriculture and high urban populations. The river often has a hypoxic water column due to high community respiration in summer. However, although nitrogen pollution is significant, N cycling is not well understood in the river. This thesis shows that NO3- and NH4+ do not typically change on the diel scale, with the exception of two sites downstream of wastewater treatment plants (WWTPs). However, N2O concentration changes dramatically. N2O concentrations are higher at night and lower during the day for most sites, but are reversed at very low-nutrient sites. N2O is therefore a sensitive indicator of changes in N cycling that may not be evident from NO3- and NH4+ concentrations or stable isotope ratios. Additionally, this work shows the importance of having a sampling design that captures diel variability in N2O. Previous work in rivers and streams worldwide focused on the appropriate N2O:NO3- ratio used to predict N2O emissions. In contrast, this thesis shows that there is a significant but very weak relationship between instantaneous N2O emissions and NO3- concentrations. However, there is a much stronger negative exponential relationship between DO and N2O. Annual N2O emissions tripled between 2006 and 2007 but NO3- masses in the river were only 10% higher, likely because river levels were lower and anoxia more prevalent in 2007. This research suggests that the IPCC needs a new conceptual model for N2O-NO3- relationships in rivers. N2O is produced in rivers, partially due to microbial processing of NO3- and NH4+ from WWTP effluent. However, WWTP effluent may also include dissolved N2O and CH4 but this previously had not been directly quantified. It was also unclear if stable isotopic ratios of NH4+, NO3-, N2O and CH4 in WWTP effluent were distinct from river sources and could be used for effluent tracing. N2O emissions from three WWTPs in the Grand River Watershed were measured over 24 hours in summer and winter. N2O emissions were similar to direct emissions from WWTPs but CH4 emissions were about an order of magnitude lower than direct WWTP emissions. This is a previously-ignored source of N2O and CH4 to the atmosphere. While stable isotopic ranges of NO3- and NH4+ were not always distinct from river sources, ??15N-N2O, ??18O-N2O and ??13C-CH4 were distinct, making them potentially useful tracers of WWTP effluent in rivers. N2O isotopic signatures may help determine production and removal processes in rivers, but isotopic effects of the major production pathway, denitrification, have not been characterized for river sediments. This was addressed by preparing anoxic laboratory incubations of river sediment from two sites (non-urban and urban) in the Grand River and measuring stable isotopic effects of N2O production via denitrification. Stable isotopic fractionations were similar to published values but, surprisingly, strongly negatively correlated to production rate, even though NO3- substrate was plentiful. This novel finding suggests that N2O reduction resulting in isotopic effects is more prevalent in high-substrate systems than previously thought, and that N2O reduction may be inhibited by high NO3- or NO2- or by lags in N2O reductase activity in high N2O-production incubations. This could explain why N2O emissions from the Grand River are lower than predicted by IPCC equations, which assume that N2O:(N2O+N2) ratios produced by denitrification are constant. Concern about NO3- export to freshwater lakes and to oceans is growing, but the role of large, eutrophic rivers in removing watershed NO3- loading via denitrification and biotic assimilation is not clear. To understand how much NO3- the Grand River receives, and how much it removes annually, a NO3- isotope mass balance for the Grand River was created. The river denitrified between 0.5% and 17% of incoming NO3-, less than the 50% suggested by the IPCC. This is surprising, as the river is well mixed, has moderate to high NO3- concentrations, experiences hypoxia (promoting denitrification), and has extensive biomass (biofilm and macrophytes) that assimilate N. However, the river???s short residence time (~3 days not counting reservoirs), organic carbon-poor sediment and mineralization of organic matter could contribute to low denitrification rates. These findings suggest that denitrification rates in rivers worldwide could be lower than previously estimated. Although error was high, most ??15N-NO3- values for losses were in the expected range for denitrification and most ??15N-NO3- values for gains were within ranges from tributaries, WWTP effluent and groundwater measured in the watershed. The model suggests that 68% to 83% of N loads to the watershed are lost before entering the Grand River, and 13% is exported to Lake Erie, leaving 5 to 19% lost in the Grand River from a combination of denitrification, assimilation and storage. These findings suggest that large rivers are much less efficient in denitrification than other locations in watersheds such as small streams, ponds, groundwater and riparian zones. They also indicate that agricultural NO3- loading is much higher than WWTP effluent, suggesting that N management strategies should focus on agricultural runoff and groundwater. Given that N2O:NO3- relationships are weak and non-linear in the Grand River, a new conceptual model for N2O:NO3- relationships is presented. First, the Grand River dataset was supplemented with data from high-oxygen streams in southern Ontario. Regression tree analysis shows a weak relationship between NO3- and N2O in these streams with no other factors (temperature, DO, NH4+, TP, DOC, etc.) improving fit. A conceptual model was then created, which posits that N2O emission variability (between and within sites) increases with NO3- concentration when NO3- concentrations are above the threshold for NO3- limitation. The global dataset does not dispute this model, though a NO3- threshold was not clear. The lack of sites with both high NO3- and high N2O may indicate a paucity of research on eutrophic sites. Alternatively, high NO3- may indicate oxic conditions (i.e. little to no denitrification to remove it) which are incompatible with very high N2O emissions. In this case, the conceptual model can be modified such that N2O variability decreases when NO3- > ~ 4 mg N/L. The work also shows that low DO consistently results in high N2O emissions but high temperatures result in a very large range of N2O emissions. This approach allows N2O emissions, which have very high variability and are difficult to predict, to be constrained to likely ranges.

碩士<br>朝陽科技大學<br>環境工程與管理系碩士班<br>92<br>The discussion of external effects associated with economic activities is highly related to the deterioration of local air quality. There are lots of benefits of economic promotion that can be estimated through the production or consumption of the economic individuals (i.e. manufacturers or consumers). However, it is not easy to weigh welfare losses caused by air quality deterioration. In order to identify the external effect, this research performs an assessment of the environmental externalities of SO2 in Tai-chung Metropolitan Area. An impact pathway approach (IPA) based on the European ExternE project was employed to evaluate the environmental impacts caused by SO2 emission. The framework of impact pathway approach has been developed to evaluate the externalities of electricity generation. It is a sequential pathway, so that emissions can be quantified, analyzed and evaluated. Nevertheless, it also needs a large amount of data to input into the model. At first, the quantity of SO2 pollutants in the studied area was estimated and allocated appropriately to each small grid. Then, air quality data was collected from the monitoring station of environmental protection administration. These data was used to estimate the dosage of exposing and the weight of SO2 through the geographic statistics (Ordinary Kriging) of the geographical information system (GIS) method. The results showed that the highest external damage caused by SO2 occurs in Longjing. It causes acute mortality about 681 YOLL and respiratory hospital admission 260 cases in 2002. After the monetary valuation of impacts, the damage cost is 123 NTD per kilogram. Compared with the current pollution fee of 12 NTD per kilogram of SO2, it needs more cost to compensate the damage cased by the power plant. In Tai-chung metropolitan area, the damage cost of SO2 is about 80 NTD per kilogram emitted. This equals the external cost about 1053 NTD per person estimated in 2002. The overall economic benefits losses were more than 4,600 million NTD. The results of this research can be used as the reference for the government to make rational decision in internalization.