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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
81

Dosimetria gel polimérica usando imagem de ressonância magnética para aplicação em radioterapia / Polymeric dosimetry gel using magnetic resonance imaging for application in Radiotherapy

Silva, Ana Luiza Quevedo Ramos da 04 December 2018 (has links)
A dosimetria em radioterapia é importante para garantir a igualdade entre a dose prescrita e a dose entregue ao paciente. Devido às inovações tecnológicas dos aparelhos de radioterapia e das técnicas de tratamento, aumentou-se a dose entregue nas regiões lesionadas. A dosimetria gel polimérica tem se mostrado promissora no controle da qualidade de fontes de radioterapia. O objetivo desse trabalho foi desenvolver um dosímetro gel, MAGIC-fm, para aplicações em dosimetria em Radioterapia e estudando características de sua resposta dosimétrica. O entendimento da construção da resposta dosimétrica, do processo de polimerização e da composição elementar do gel foi realizado através de imagem por ressonância magnética, em intensidades de campo magnético de 3T, 7T e 9,4T, com sequências de leitura de dispersão em T1, Espectroscopia Resolvida no Tempo, Pulse Size Ratio, Relaxometria em T2 e Efeito Overhauser Nuclear. Embora o dosímetro desenvolvido não tenha apresentado dispersão em T1, com essa sequência foi possível determinar R1 e R2, que podem ser utilizados em dosimetria. Através das análises de espectroscopia, verificou-se a contribuição de cada elemento do gel na resposta dosimétrica. O aparecimento de efeitos NOE conforme o aumento da dose, mostrou-se promissora para detecção de dose em gel dosimétrico. O gel MAGIC-fm apresentou sensibilidade 40% maior que a formulação original do gel MAGIC-f, além de saturação de resposta acima de 50 Gy. Utilizando-se a técnica de relaxometria avaliou-se a dependência de resposta com a energia e a taxa de dose em feixes de fótons e elétrons tipicamente utilizados em tratamentos de radioterapia. O processo de calibração do dosímetro foi estudado, concluindo-se que o uso de objetos simuladores com tamanhos similares aqueles de interesse clínico devem ser usados. Uma aplicação de dosimetria em fonte de braquiterapia de alta taxa de dose de 192Ir foi realizada, com resultados comparados com dados do sistema de planejamento. Os resultados apresentaram concordância em mais de 95% dos pontos das regiões analisadas, incluindo regiões de alta dose, concluindo-se que o gel desenvolvido, MAGIC-fm, é promissor no controle da qualidade de fontes de radioterapia / Dosimetry in radiotherapy is important to ensure equality between the prescribed dose and the delivered dose to the patient. Due to the technological innovations of the radiotherapy machines and the treatment techniques, increased the delivered dose in the injured regions. Polymer gel dosimetry has shown promising in the quality control of radiotherapy sources. The purpose of this work was to develop a dosimeter gel, MAGIC-fm, for applications in dosimetry in Radiotherapy and to study characteristics of its dosimetric response. The understanding of dosimetric response construction, the polymerization process and the gel elemental composition was performed by magnetic resonance imaging at magnetic field intensities of 3T, 7T and 9.4T, with reading sequences of T1 dispersion, Time-Resolved Spectroscopy, Pulse Size Ratio, T2 Relaxometry and Nuclear Overhauser Effect. Although the developed dosimeter did not present T1 dispersion, with this sequence it was possible to determine R1 and R2, which can be used in dosimetry. Through the spectroscopy analyzes, the contribution of each gel element in the dosimetric response was verified. The appearance of NOE effects as the dose increased, was shown to be promising for dosimetric gel dose detection. The MAGIC-fm gel showed 40% sensitivity higher than the original MAGIC-f gel formulation, in addition to response saturation above 50 Gy. Using the relaxometry technique, the dependence of energy and dose rate response on photon and electron beams typically used in radiotherapy treatments was evaluated. The dosimeter calibration process was studied, concluding that the use of phantoms with similar sizes of those of clinical interest should be used. An application of dosimetry in a high dose rate 192Ir brachytherapy source was performed, with results compared with data from the planning system. The results showed a concordance in more than 95% of the points of the analyzed regions, including regions of high dose, concluding that the developed gel, MAGIC-fm, is promising in the quality control of radiotherapy sources
82

The Study of the Colossal Magnetoresistance Tunneling

Wu, Tsung-Chan 27 July 2002 (has links)
We imitated the sandwich structure of TMR(Tunneling Magnetoresistance) to apply to CMR(Colossal Magnetoresistance) material . We choose one of the Colossal Magnetoresistance material La0.67Sr0.33MnO3(113) to be the Ferromagnetic(FM) layers as top and bottom layer in sandwich structure and use La0.67Sr0.33MnO3 ¡P SrO(214) to be middle layer which have Antiferromagnetic(AFM) property to form FM-AFM-FM structure. The FM and AFM layer can match their lattice in interface joint. What its purpose is to use this structure to enhance SPT (Spin Polarization Tunneling) effect and let spintronics can periodical spin-flip in supper lattice structure of antiferromagnetic. Upon this compose we try to show increase the LFMR (Low Field Magnetoresistance) by use CMR. The experiment result shows maybe the film structure damage occurred in our made TMR tunneling device process (ex. Ion etching process), so we should improvement the process to get the exactly experiment data. Additional, due to the alignment of the moment of La0.67Sr0.33MnO3 is unstable, the back and forth hysteresis loop can¡¦t overlap, So that afterwards we can use the more stable material La0.67Ca0.33MnO3 which have more stable moment.
83

Nanofils suspendus en silicium vibrants à haute fréquence : étude théorique et expérimentale / Suspended silicon nanowires resonating at high frequency : theoretical and experimental study

Koumela, Alexandra 17 January 2013 (has links)
La miniaturisation des composants électroniques de l'échelle micro à l'échelle nano a entrainé aussi une miniaturisation des systèmes micro électromécaniques (MEMS). Cependant, la transition de MEMS à NEMS (systèmes nano électromécaniques) ne se résume pas simplement une réduction de taille. En fait, les méthodes d'actionnement et de détection utilisées couramment à l'échelle micro ne sont pas toujours efficaces à l'échelle nano. En plus, la fabrication des composants nanométriques avec des méthodes top-down est un défi à cause des limites de résolution. En surmontant ces difficultés, nous avons fabriqué et caractérisé des résonateurs à base de nanofils en silicium suspendus avec des petites sections de 30nm par 40nm et de longueurs allant de 1.5-3.5μm. L'actionnement de ces résonateurs est électrostatique et la détection est effectué avec deux mécanismes indépendants : (i) l'effet piezo résistif de deuxième ordre et (ii) l'effet de champ. Les mesures en régime statique nous ont permis de valider la présence de ces deux mécanismes et d'extraire les paramètres correspondants tels que le facteur de jauge et la transconductance du nanofil. Aussi, pour la première fois, ces deux principes ont été utilisés en alternance pour détecter la résonance du même nanofil. Les résultats obtenus avec ces transductions sont très prometteurs. La distinction entre les deux méthodes de transduction a été possible grâce à l'hétérodynage qui permet de sélectionner des phénomènes qui se produisent à la fréquence naturelle du dispositif ou au double de cette fréquence. Dans le but d'évaluer les performances de ces résonateurs pour de potentielles applications, nous avons mesuré la variance d'Allan. La stabilité de ces résonateurs pour des temps courts est du même ordre que celle des MEMS en silicium ce qui permet d'envisager l'utilisation de nanofils de silicium pour concevoir des bases de temps. Ces dispositifs nanométriques peuvent également être utilisés comme détecteur de masse avec des résolutions en masse de l'ordre du zg / The continuous miniaturization of electronics from micro to nano scale has impacted also the micro electromechanical systems (MEMS). However, the transition from MEMS to NEMS (nano electromechanical systems) is not only a matter of size. The actuation and detection principles used for efficient transduction at the microscale are not always efficient at the nanoscale. Also, top-down fabrication for nanometric devices becomes challenging due to resolution limits. Overcoming such difficulties, we were able to fabricate and characterize suspended silicon nanowire resonators with cross sections as small as 30nm by 40nm and lengths of 1.5-3.5μm. The actuation of these resonators was electrostatic, while the detection was performed with two independent physical phenomena: (i) the piezoresistive effect of second order and (ii) the field-effect. Measurements in static regime permitted us to validate the presence of these two mechanisms and extract related parameters such as the gauge factor and the nanowire transconductance. Then, for the first time, these two principles were used alternatively on the same silicon nanowire device for resonance detection and showed promising results. The distinction between the two was possible thanks to the down-mixed technique which could differentiate phenomena happening at the natural resonant frequency of the nanowire and twice this frequency. In order to evaluate the performances of these resonators, Allan deviation measurements were performed. It seems that the short-term stability of these devices is in the spectrum of other silicon MEMS devices for time reference applications and that potentially silicon nanowire resonators could be conceived for time keeping. Another potential application of these devices consists in mass sensing with mass resolutions close to the state of the art (<zg)
84

FM vysílač APRS telemetrických dat v pásmu 435 MHz / FM Transmitter of APRS Telemetry in 435 MHz Band

Klíma, Martin January 2011 (has links)
FM transmitter APRS of telemetric data is device able to measure telemetric values from its ambient. It is able to send this data to user on earth by radio frequency channel. This device can create data frames, with proper formatting allowing sending data. It operates in 435 MHz band, uses FSK and AFSK modulation. This work describes basic information of used protocols, electronic connection of this transmitter and software equipment.
85

Truck Connectivity Platform Using Software Defined Radios

Vasan, Srinath January 2019 (has links)
Hardware updates and feature updates of electronic equipment can take a long time for market implementations. Technology tends to become obsolete by the time the update is launched into the market. In the automotive industry, the service entertainment module (SEM) containing the core logic for Amplitude Modulation (AM), Frequency Modulation (FM), and Digital Audio Broadcasting (DAB) radio tuners lack the facility for software-based updates. One of the major challenges for the infotainment/entertainment modules in the automotive industry is to have a single radio module that can support software updates and multistandard radio technologies from different countries. Software Defined Radios (SDR) can be used to deal with this problem as SDR is a platform to prototype or develop new communication protocols as well as add new features or capabilities to the existing protocols without requiring major capital expenditures. SDR is a cost-effective radio platform because it can update radio equipment on the fly and provide additional functionality without requiring hardware modifications. By means of software instead of hardware updates, development loops could be shortened and manufacturing costs are reduced. In this thesis, a thorough comparison of a hardware-based tuner and a software-based tuner is performed in the presence of AM/FM/DAB modulated signals based on the metrics specified in ETSI EN 303 345-1 including sensitivity, adjacent channel suppression, far-off channel suppression, cross-modulation, third-order intermodulation, etc. After performance evaluation and comparison, it can be proven that the SDR based system can perform as well as the hardware tuner used in the SEM unit. / Hårdvaruuppdateringar och funktionsuppdateringar av elektronisk utrustning kan ta lång tid för marknadsimplementeringar. Teknik tenderar att bli föråldrad när uppdateringen lanseras på marknaden. Inom fordonsindustrin saknar servicunderhållningsmodulen (SEM) som innehåller kärnlogiken för Amplitude Modulation (AM), Frequency Modulation (FM) och Digital Audio Broadcasting (DAB) radiostemmare möjligheten för programvarubaserade uppdateringar. En av de största utmaningarna för infotainment/ underhållningsmodulerna i bilindustrin är att ha en enda radiomodul som kan stödja programvaruuppdateringar och multistandardradioteknologier från olika länder. Programvarudefinierade radioapparater (SDR) kan användas för att hantera detta problem eftersom SDR är en plattform för att prototypa eller utveckla nya kommunikationsprotokoll samt lägga till nya funktioner eller kapaciteter till de befintliga protokollen utan att kräva stora investeringar. SDR är en kostnadseffektiv radioplattform eftersom den kan uppdatera radioutrustning i farten och ge ytterligare funktionalitet utan att kräva hårdvaruändringar. Med hjälp av mjukvara istället för hårdvaruuppdateringar kan utvecklingsslingor förkortas och tillverkningskostnaderna reduceras. I denna avhandling utförs en grundlig jämförelse av en hårdvarubaserad tuner och en mjukvarubaserad tuner i närvaro av AM / FM / DABmodulerade signaler baserade på mätvärden som specificeras i ETSI EN 303 345-1 inklusive känslighet, intilliggande kanalsuppression, avlägsna kanalundertryckning, tvärmodulering, tredje ordning intermodulering etc. Efter utvärdering och jämförelse av prestanda kan det bevisas att det SDR-baserade systemet kan fungera liksom hårdvarutunern som används i SEM-enheten.
86

Vilken effekt har framtida klimat på strömningsmönster i Ekoln - en modelleringsstudie baserad på MIKE 3 FM / The influence of future climate on circulation patterns in the Ekoln basin - a modelling study based on MIKE 3 FM

Lindqvist, Sandra January 2019 (has links)
For centuries in the future, the climate on Earth will be affected by the global warming.Effects as melting ices, increasing sea levels and extreme weather, are all consequencesof the high amount of carbon dioxide (CO2), that we humans have caused. In Sweden,can climate effects like higher temperatures, longer vegetation periods and greaterseasonal variations in water fluxes, be expected. Due to climate changes and anincreasing population, the drinking water production in Uppsala will be affected. Interms of securing the drinking water production in the future, Uppsala Vatten och Avfall AB are investigating the possibility to use the Ekoln basin in lake Mälaren, as acomplementary raw water catchment area. In order to keep a secure drinking water production, in regard to quantity and quality, itis of interest to investigate how fluxes and water quality will be affected in the future.The annual pattern of water mixing, with summer- and winter stratification, and overturnduring spring and autumn, is something that significantly affects the water quality in theSwedish lakes. With the aim to study how the annual pattern of water mixing in theEkoln basin, might change due to future climate changes, hydrodynamic modelling wasperformed on a model area consisting of the Ekoln basin with adjacently bays. A hydrodynamic (3D) transport model of type MIKE 3 Flow Model FM, created byTyréns AB for simulating transport of pollutions, was calibrated and adapted to simulatetemperature profiles in the model area. To be able to study the annual pattern of watermixing, the model was also adapted to simulate a period of a year. Three scenarios weresimulated, one reference year and two future scenarios, where the future scenarios werebased on the climate scenarios RCP4.5 and RCP8.5 in year 2050. The calibration of the model was successful, and the calculation time was reduced byadapting the mesh. Results from the three scenarios, showed that the period with summerstratification might become nine days longer by RCP4.5 in year 2050, compared to thereference scenario. Simulation of RCP8.5 during the same time period, did not showany changes. By RCP8.5 it is possible that water temperatures in the epilimnion, areincreasing and that there will be no winter stratification. The temperature in the surfacewater are affected by the air temperature, in future studies it is in interest to investigatehow stratification and cirkulation will be affected by changes in wind speed and winddirection, how different types of wind data effect the results, it is also in interest to studychanges during a time period longer than one year. / Den globala uppvärmningen kommer att påverka Jordens klimat i många sekel framöver.Effekter som smältande isar, stigande havsnivåer och extremare väder, är allakonsekvenser av de enorma utsläpp koldioxid (CO2), som vi människor orsakat. ISverige kan vi i framtiden vänta oss varmare temperaturer, längre vegetationsperioderoch flöden med stora säsongsvariationer. I Uppsala kommer de framtidaklimatförändringarna i samverkan med en växande befolkning att påverka stadensdricksvattenproduktion. Uppsala Vatten och avfall AB undersöker idag möjligheten tillatt använda Mälarbassängen Ekoln som kompletterande råvattentäkt. För att säkerställa en säker dricksvattenproduktion, både utifrån den kvantitet ochkvalitet som krävs, är det av intresse att veta hur flöden och vattenkvalitet i Ekoln kankomma att utvecklas i framtiden. Något som i stor grad påverkar vattenkvaliteten i våraSvenska sjöar, är den årstidsbundna cirkulationen, med vinter- och sommarstagnation,samt vår- och höstcirkulation. För att undersöka hur den årstidsbundna cirkulationen iEkoln kan komma att förändras med framtida klimat, utfördes hydrodynamiskmodellering för sjön med intilliggande vikar. En bestående tredimensionell spridningsmodell av typ MIKE 3 Flow Model FM, skapadför att simulera spridning av avloppsvatten i Ekoln, erhölls från Tyréns AB. Modellenkalibrerades och anpassades för att simulera temperaturprofiler i sjön. För att täcka inbeteendet för den årstidsbundna cirkulationen anpassades modellen till att simulera etthelt år. Modellen kördes för ett referensår, samt för de två strålningsdrivningsscenariernaRCP4.5 och RCP8.5 vid år 2050. Kalibrering av modellen var lyckad och beräkningstiden förkortades genom anpassningav beräkningsnätet. Resultat från simuleringar visade på att sommarstagnation kanförekomma nio dagar längre vid RCP4.5 för år 2050, än under referensåret. Ingenförändring förväntas vid RCP8.5 under samma tidsperiod. Vid RCP8.5 förväntas dockvattentemperaturer i epilimnion att stiga och vinterstagnation förekommer ej.Temperaturer i vattenmassans övre skikt påverkas i hög grad av lufttemperatur och vidfortsatta studier är det även av intresse att undersöka hur skiktning och cirkulationpåverkas av förändrade vindförhållanden, hur olika drivdata för vindförhållandenpåverkar resultatet samt att undersöka en tidsperiod som är längre än ett år.
87

O Jornalismo nas Rádios Comunitárias

Rosembach, Cilto José 10 October 2006 (has links)
Made available in DSpace on 2016-04-26T18:15:56Z (GMT). No. of bitstreams: 1 COS - Cilto Jose Rosembach.pdf: 1195990 bytes, checksum: 8ddd58d859ac81042e7772b2ca23da3e (MD5) Previous issue date: 2006-10-10 / The present study analyzes journalism in community radios from the paradigm of alternative, grassroots communication. The analysis is done from the historical context of community radios in Brazil. This work uses the case study as the methodological basis and examines the programming of community journalism in two community radios in the state of São Paulo from a theoretical reference that clarifies grassroots communication and emphasizes the concepts of community journalism. Two community stations, Radio Cantareira FM 107.5 Vila Isabel, District of Brasilândia, São Paulo, capital, on the air since 1995 and Radio Nova Esperança FM 87.9, Vila Esperança, Cubatão, São Paulo, on the air since 2003, are analyzed. In the final considerations, based on the studies done, we present the possibilities of the contribution of community journalism to the democratization of communication, and to the construction of citizenship. It also shows the limits and challenges of this paradigm of communication / O presente estudo analisa o jornalismo nas rádios comunitárias a partir do paradigma da comunicação popular, alternativa e da contextualização histórica das rádios comunitárias no Brasil. A programação jornalística de duas rádios comunitárias no Estado de São Paulo é analisada a partir do referencial teórico que elucida a comunicação popular e prioriza os conceitos de jornalismo popular. São analisadas a Rádio Cantareira FM 107,5, de Vila Isabel, distrito de Brasilândia, São Paulo, capital, no ar desde 1995, e a Rádio Nova Esperança FM 87,9, de Vila Esperança, Cubatão/SP, no ar desde 2003. Nas considerações finais, baseadas em estudos de caso, apresentamos as possibilidades de contribuição do jornalismo comunitário para a democratização da comunicação e a construção da cidadania. São também apontados os limites e os desafios desse paradigama de comunicação
88

Contributions to the analysis of multicomponent signals : synchrosqueezing and associated methods / Contributions à l'analyse des signaux multicomposantes : synchrosqueezing et méthodes associées

Pham, Duong Hung 17 September 2018 (has links)
De nombreux signaux physiques incluant des signaux audio (musique, parole), médicaux (ECG, PCG), de mammifères marins ou d'ondes gravitationnelles peuvent être modélisés comme une superposition d'ondes modulées en amplitude et en fréquence (modes AM-FM), appelés signaux multicomposantes (SMCs). L'analyse temps-fréquence (TF) joue un rôle central pour la caractérisation de tels signaux et, dans ce cadre, diverses méthodes ont été développées au cours de la dernière décennie. Néanmoins, ces méthodes souffrent d'une limitation intrinsèque appelée le principe d'incertitude. Dans ce contexte, la méthode de réallocation (MR) a été développée visant à améliorer les représentations TF (RTFs) données respectivement par la transformée de Fourier à court terme (TFCT) et la transformée en ondelette continue (TOC), en les concentrant autour des lignes de crête correspondant aux fréquences instantanées. Malheureusement, elle ne permet pas de reconstruction des modes, contrairement à sa variante récente connue sous le nom de transformée synchrosqueezée (TSS). Toutefois, de nombreux problèmes associés à cette dernière restent encore à traiter tels que le traitement des fortes modulations en fréquence, la reconstruction des modes d'un SMC à partir de sa TFCT sous-échantillonnée or l'estimation des signatures TF de modes irréguliers et discontinus. Cette thèse traite principalement de tels problèmes afin de construire des nouvelles méthodes TF inversibles plus puissantes et précises pour l'analyse des SMCs.Cette thèse offre six nouvelles contributions précieuses. La première contribution introduit une extension de TSS d'ordre deux appliqué à la TOC ainsi qu'une discussion sur son analyse théorique et sa mise en œuvre pratique. La seconde contribution propose une généralisation des techniques de synchrosqueezing construites sur la TFCT, connue sous le nom de transformée synchrosqueezée d'ordre supérieur (FTSSn), qui permet de mieux traiter une large gamme de SMCs. La troisième contribution propose une nouvelle technique utilisant sur la transformée synchrosqueezée appliquée à la TFCT de second ordre (FTSS2) et une procédure de démodulation, appelée DTSS2, conduisant à une meilleure performance de la reconstruction des modes. La quatrième contribution est celle d'une nouvelle approche permettant la récupération des modes d'un SMC à partir de sa TFCT sous-échantillonnée. La cinquième contribution présente une technique améliorée, appelée calcul de représentation des contours adaptatifs (CRCA), utilisée pour une estimation efficace des signatures TF d'une plus grande classe de SMCs. La dernière contribution est celle d'une analyse conjointe entre l'CRCA et la factorisation matricielle non-négative (FMN) pour un débruitage performant des signaux phonocardiogrammes (PCG). / Many physical signals including audio (music, speech), medical data (ECG, PCG), marine mammals or gravitational-waves can be accurately modeled as a superposition of amplitude and frequency-modulated waves (AM-FM modes), called multicomponent signals (MCSs). Time-frequency (TF) analysis plays a central role in characterizing such signals and in that framework, numerous methods have been proposed over the last decade. However, these methods suffer from an intrinsic limitation known as the uncertainty principle. In this regard, reassignment method (RM) was developed with the purpose of sharpening TF representations (TFRs) given respectively by the short-time Fourier transform (STFT) or the continuous wavelet transform (CWT). Unfortunately, it did not allow for mode reconstruction, in opposition to its recent variant known as synchrosqueezing transforms (SST). Nevertheless, many critical problems associated with the latter still remain to be addressed such as the weak frequency modulation condition, the mode retrieval of an MCS from its downsampled STFT or the TF signature estimation of irregular and discontinuous signals. This dissertation mainly deals with such problems in order to provide more powerful and accurate invertible TF methods for analyzing MCSs.This dissertation gives six valuable contributions. The first one introduces a second-order extension of wavelet-based SST along with a discussion on its theoretical analysis and practical implementation. The second one puts forward a generalization of existing STFT-based synchrosqueezing techniques known as the high-order STFT-based SST (FSSTn) that enables to better handle a wide range of MCSs. The third one proposes a new technique established on the second-order STFT-based SST (FSST2) and demodulation procedure, called demodulation-FSST2-based technique (DSST2), enabling a better performance of mode reconstruction. The fourth contribution is that of a novel approach allowing for the retrieval of modes of an MCS from its downsampled STFT. The fifth one presents an improved method developed in the reassignment framework, called adaptive contour representation computation (ACRC), for an efficient estimation of TF signatures of a larger class of MCSs. The last contribution is that of a joint analysis of ACRC with non-negative matrix factorization (NMF) to enable an effective denoising of phonocardiogram (PCG) signals.
89

Physiological responses of Ulva fasciata Delile (Ulvales, Chlorophyta): comparison of two populations from thermally distinct sites from Brazilian coast / Respostas fisiológicas de Ulva fasciata Delile (Ulvales, Chlorophyta): comparação de duas populações de locais termicamente distintos do litoral brasileiro

Martins, Nuno Tavares 10 January 2017 (has links)
In a global warming scenario, an increase temperature is expected in addition to the occurrence and intensity of extreme climate events. One example of extreme events is the marine heat waves, which are a major threat to marine macroalgae. Ulva fasciata is a cosmopolitan species that occur in the whole Brazilian coast. This study was performed in two regions of Rio de Janeiro State (RJ) coast. Both regions are tropical, however, Arraial do Cabo/RJ is naturally colder than Niterói/RJ due upwelling phenomenon. This study aimed to: (i) confirm that U. fasciata individuals from these two Brazilian coast regions are of the same species; and (ii), physiologically analyze individuals of U. fasciata in the field and under in-laboratory controlled temperature experiment. We hypothesized that U. fasciata populations grown at thermally different locations would present distinct ecophysiological responses. In the field, it was accessed maximum quantum yield (Fv/Fm) and pigment content, and in laboratory, it was also evaluated growth rate. The in-laboratory controlled experiment comprised three phases: (i) a temperature gradient; (ii) a 5-day heat wave (+ 5 oC); and (iii) a 5-day recovery (- 5 oC). The molecular data allow us to state that the two populations belong to the same species. No differences of the fluorescence-derived factors were observed between individuals from both populations in the field, suggesting acclimation. However, differences were detected along all three experimental phases. The analysis of pigment content field data evidenced that individuals from the population of Niterói (warmer site) had higher concentrations of chlorophyll a than individuals from Arraial do Cabo (colder site). However, individuals of population from Niterói when cultured at 21 oC showed the lowest values of pigment. The differences observed suggest ecotypes. In conclusion, as the planet becomes warmer and extreme weather events become more frequent, the likelihood that heat wave to occur is higher. Therefore, U. fasciata from Arraial do Cabo showed better physiological responses to the effects of heat wave, what could confer them higher competitiveness ability to overcome thermal stress / Num cenário de aquecimento global, um aumento da temperatura é esperado, assim como a ocorrência e intensidade de eventos climáticos extremos. Um exemplo de evento extremo são as ondas de calor marinhas, que são a principal ameaça a macroalgas marinhas. Ulva fasciata é uma espécie cosmopolita que ocorre em toda costa brasileira. Esse estudo foi realizado em duas regiões da costa do Estado do Rio de Janeiro (RJ). Ambas regiões são tropicais, mas Arraial do Cabo/RJ é naturalmente mais fria que Niterói/RJ devido ao fenômeno de ressurgência. Esse estudo objetivou: (i), confirmar que os indivíduos de U. fasciata dessas duas localidades da costa brasileira são da mesma espécie; e (ii) analisar fisiologicamente indivíduos de U. fasciata em campo e em experimentos de temperatura em condições controladas de laboratório. Nossa hipótese era de que populações de U. fasciata procedentes de localidades termicamente diferentes iriam apresentar respostas ecofisiológicas distintas. Em campo, foi acessado o rendimento quântico máximo (Fv/Fm) e o conteúdo pigmentar, e em laboratório, foi também avaliada a taxa de crescimento. O experimento em condições controladas de laboratório consistiu de três fases: (i) gradiente de temperatura; (ii) onda de calor (+5 oC) de 5 dias; e (iii) recuperação (- 4 oC) de 5 dias. Os dados moleculares permitiram afirmar que as duas populações pertencem à mesma espécie. Não foram detectadas diferenças nos fatores derivados da fluorescência entre os indivíduos das duas populações avaliadas em campo, sugerindo aclimatação. Contudo, foram detectadas diferenças ao longo das três fases experimentais. A análise do conteúdo pigmentar em campo evidenciou que os indivíduos da população de Niterói (região mais quente) tinham mais clorofila a do que os indivíduos de Arraial do Cabo (região mais fria). No entanto, indivíduos da população de Niterói, quando cultivados em 21 oC, mostraram valores menores de pigmentos. As diferenças observadas sugerem ecótipos. Em conclusão, conforme o planeta se torna mais quente e eventos extremos climáticos se tornam mais frequentes, a probabilidade de ocorrência de ondas de calor é maior. Dessa forma, U. fasciata de Arraial do Cabo mostro melhor resposta fisiológica aos efeitos da onda de calor, o que lhe pode conferir maior capacidade de competição para superar estresses térmicos
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共積模型之估計與檢定方法研究 / Cointegrated Model Analysis:Estimation,and Testing

陶志偉, Tao, Chih Wei Unknown Date (has links)
介紹幾種具有良好性質的共積模型估計方法,這些方法因其估計目的不同,而採取相異的模型表示式、相異的估計準則。在論文的連貫性與完整性考量上,須從最簡單的單變數非恆定模型開始介紹整篇論文的基礎。考慮變數間的累積性質關聯,採取空間投影的方法,將共積向量空間、模型虛假迴歸性質、甚至非恆定模型的單根來源連結在一起。充份說明了共積模型裡變數彼此的關聯後,採用共積空間表示式來完備誤差修正表示式裡無法說明的變數相關性。兩種表示式相互配合後,可以建立不同估計方法一致的比較基礎。比較不同估計方法的同時,也系統的介紹幾種估計方法。其中Phillips的完全修正法是主要介紹的估計法,也是後續不同方法間的比較基礎。比較不同方法的異同,主要著重點在於不同方法的估計準則或是修正動機。比較後的結論,可以對照原來方法的估計步驟,唯有暸解不同角度看出的變數性質,才能更精確的掌握估計方法。

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