This work presents results on the study of mechanisms and performance of negative ion drift and gas gain in gas-filled radiation detectors with electronegative fill gases. Negative ions drift with slow drift velocity and the lowest possible (thermal limit) diffusion, which leads to relaxed requirements for readout electronics without sacrificing accuracy. Slow drift velocity and low diffusion are the bases for this work because these characteristics are highly desirable for space-based detectors and for low pressure Time Projection Chambers (TPCs) used to make direction sensitive searches for Galactic Dark Matter. The present work led to two major successes: (1) Nitromethane (CH3NO2) was discovered as a new electronegative fill gas for TPCs. Nitromethane anions drift even slower (mobility = 0.032 m2·T/V ·s) than the only other known capture agent, carbon disulfide (CS2, mobility = 0.036 m2·T/V ·s), and the measured longitudinal diffusion remains at the thermodynamic (lower) limit for fields up to 7 V/cmT. Nitromethane is of particular interest for X-ray photoelectric polarimeters in the 2-10 keV energy range because of its low atomic number (Z). (2) Using a Diethorn plot, the mechanism which initiates electron avalanches in electronegative gas mixtures was accounted for. The Diethorn plot parameter Emin, is the minimum field needed to start avalanche gain in a proportional counter. Electronegative gases were found to have extremely large pressure-reduced starting fields (10-50 times larger than electron gases) which are themselves approximately independent of pressure. This can only be accounted for by a collisional ionization mechanism leading to the release of electrons from the ions and subsequent development of gain through a normal Townsend avalanche. The collision cross-section (σc) calculated from drift velocity data allows an estimate of Emin to be made which agrees with the experimental findings (5 - 25 % difference). The light output from Townsend avalanches has been proposed as an alternative readout mechanism for TPCs. The light output from negative ion avalanches was investigated using a Negative Ion Drift Chamber (NIDC) with a Gaseous Electron Multiplier (GEM)-like device as the amplification structure, viewed through a quartz window by a photomultiplier tube. This study allowed an upper limit of light output to be assigned to several negative ion gas mixtures. Finally, a Micromegas NIDC was assembled to test the performance of negative ion mixtures in this gain device. The detector was stable and operated at gas gains of ∼ 104 in an electron gas mixture (argon-isobutane). However, with the two negative ion gases studied, CS2 and CH3NO2, high voltage breakdown and microphonic noise developed before appreciable gain was obtained. / Physics

Une grande ‘Chambre à Projection Temporelle’ (TPC) est un candidat pour la détection et la mesure des traces chargées auprès de l’ILC, collisionneur linéaire d’électrons et de positons de 31 km permettant d’atteindre des énergies dans le centre de masse de 250 GeV à 1 TeV. Le travail de R&D décrit dans cette thèse porte sur un type nouveau de TPC, dont la lecture est assurée par des Micromégas à anode résistive. Ce dispositif permet de répartir le signal électrique sur plusieurs carreaux, même lorsque la charge est déposée sur un seul carreau. Il permet aussi de protéger l’électronique, ce qui est utilisé dans notre prototype pour miniaturiser les cartes de lecture. Dans ce travail, des modules Micromégas ont été testés et caractérisés, dans un premier temps, en faisceau, un par un au centre de la chambre, puis 7 modules montés en même temps de façon à couvrir la surface. Egalement, des tests sur un banc équipé d’une source de ⁵⁵Fe ont permis de caractériser les 7 modules utilisés. Une résolution en position de 60 microns par ligne de carreaux est obtenue à petite distance de dérive. L’uniformité est aussi évaluée, et des distorsions pouvant atteindre environ 500 microns sont observées. L’ensemble des résultats démontre l’adéquation de ce type de lecture à la TPC pour l’ILC. La fraction de retour des ions est également mesurée à l’aide d’un détecteur de même géométrie et avec le même gaz que ceux utilisés dans ces tests, et la loi en rapport inverse des champs est validée à nouveau dans ces conditions. La même technique est appliquée à la réalisation d’un imageur neutron, consistant en une TPC Micromégas ‘plate’ précédée d’un film convertisseur de 1mm d’épaisseur. Les protons éjectés par les neutrons sont ‘suivis à la trace’ dans le volume gazeux, ce qui permet de reconstruire avec une précision meilleure que le millimètre le point d’origine du neutron. / The study of the fundamental building blocks of matter necessitates always more powerful accelerators. New particles are produced in high energy collisions of protons or electrons. The by-Products of these collisions are detected in large apparatus surrounding the interaction point. The 125 GeV Higgs particle discovered at LHC will be studied in detail in the next e⁺e⁻ collider. The leading project for this is called ILC. The team that I joined is working on the R&D for a Time Projection Chamber (TPC) to detect the charged tracks by the ionization they leave in a gas volume, optimised for use at ILC. This primary ionization is amplified by the so-Called Micromegas device, with a charge-Sharing anode made of a resistive-Capacitive coating. After a presentation of the physics motivation for the ILC and ILD detector, I will review the principle of operation of a TPC (Chapter 2) and underline the advantages of the Micromegas readout with charge sharing. The main part of this PhD work concerns the detailed study of up to 12 prototypes of various kinds. The modules and their readout electronics are described in Chapter 3. A test-Bench setup has been assembled at CERN (Chapter 4) to study the response to a ⁵⁵Fe source, allowing an energy calibration and a uniformity study. In Chapter 5, the ion backflow is studied using a bulk Micromegas and the gas gain is measured using a calibrated electronics chain. With the same setup, the electron transparency is measured as a function of the field ratio (drift/amplification). Also, several beam tests have been carried out at DESY with a 5 GeV electron beam in a 1 T superconducting magnet. These beam tests allowed the detailed study of the spatial resolution. In the final test, the endplate was equipped with seven modules, bringing sensitivity to misalignment and distortions. Such a study required software developments (Chapter 6) to make optimal use of the charge sharing and to reconstruct multiple tracks through several modules with a Kalman filter algorithm. The results of these studies are given in Chapter 7. The TPC technique has been applied to neutron imaging in collaboration with the University of Lanzhou. A test using a neutron source has been carried out in China. The results are reported in Chapter 8.

Submitted by JÚLIO HEBER SILVA (julioheber@yahoo.com.br) on 2017-05-19T17:06:06Z No. of bitstreams: 2 Dissertação - Alex Rabelo Ferreira - 2017.pdf: 1520702 bytes, checksum: 4d6d16d4b1045c459e8d23fc2f6a4c69 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2017-05-22T10:41:24Z (GMT) No. of bitstreams: 2 Dissertação - Alex Rabelo Ferreira - 2017.pdf: 1520702 bytes, checksum: 4d6d16d4b1045c459e8d23fc2f6a4c69 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2017-05-22T10:41:24Z (GMT). No. of bitstreams: 2 Dissertação - Alex Rabelo Ferreira - 2017.pdf: 1520702 bytes, checksum: 4d6d16d4b1045c459e8d23fc2f6a4c69 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2017-04-25 / Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPq / In large-scale data centers, power management techniques such as Dynamic Voltage/Frequency Scaling (DVFS), virtual machine consolidation, and power-capping mechanisms promise impressive energy savings compared to traditional resource management strategies. Most of these techniques rely on coarse-grained monitoring of the workload behavior to apply their optimizations. However, coarse-grained monitoring and black box observations are not satisfactory for predicting the behavior of bursty workloads such as those observed in enterprise, Web servers. In this work, we propose an analytical model to estimate the energy consumption of multi-tier Web Systems. Differently from previous works, our model captures the consumption pattern at the level of fine-grained transactions and for each tier of the system. In addition, our model is based only on CPU utilization and server architectural parameters, which can be easily obtained in today’s production environments. We demonstrate the effectiveness of our model in a real-world experimentation environment, based on the TPC-W benchmark. Results show that our model is able to estimate the energy consumption for a Web system with an average relative error of 6.5% in the worst-case scenario, whereas more complex models of the literature present errors within the same order of magnitude. / Em grandes centros de dados, técnicas de gerenciamento de energia como Dynamic Voltage/Frequency Scaling (DVFS), consolidação de máquinas virtuais e mecanismos de limitação de energia prometem grande economia de energia quando comparados a métodos tradicionais de gerenciamento de recursos. A maioria dessas técnicas utilizam mecanismos caixas-pretas para monitorar o comportamento da carga de trabalho. Contudo, esse tipo de monitoramento não é satisfatório para prever os fenômenos de rajadas, comumente encontrados em serviços e aplicações Web. Neste trabalho, propomos um modelo analí- tico para estimar o consumo de energia de Sistemas Web multi-camadas. Diferentemente de outros trabalhos, nosso modelo captura o padrão de consumo desses sistemas na granularidade de transações e para cada camada do sistema. Além disso, nosso modelo se baseia apenas na utilização de CPU e em parâmetros arquiteturais do servidor, os quais podem ser facilmente obtidos nos ambientes de produção atuais. Demonstramos a efetividade do nosso modelo em um ambiente de experimentação real, baseado no benchmark TPC-W. Os resultados obtidos mostram que nosso modelo é capaz de estimar o consumo de energia para um sistema Web com um erro relativo médio de 6,5% para o pior cenário, enquanto modelos mais complexos da literatura apresentam erros com a mesma ordem de grandeza.

Les travaux décrits dans cette thèse sont centrés sur la caractérisation et l’optimisation d’une camera Compton à phase unique au xénon liquide pour des applications médicales. Le détecteur a été conçu pour exploiter les avantages d’une technique d’imagerie médicale innovante appelée l’imagerie 3γ. Elle vise à l’obtention de la position en 3D d’une source radioactive avec une très haute sensibilité et une réduction importante de la dose administrée au patient. L’imagerie 3γ est basée sur la détection en coïncidence de 3 photons gamma émis par un émetteur spécifique (+β, γ), le 44Sc. Un premier prototype de camera Compton au xénon liquide a été développé par le laboratoire Subatech à travers le projet XEMIS (Xenon Medical Imaging System), pour démontrer la faisabilité de l’imagerie 3γ. Ce nouveau système de détection comporte un système de cryogénie avancé et une électronique front-end à très faible bruit qui fonctionne à la température du xénon liquide. Ce travail a contribué à la caractérisation de la réponse du détecteur et à l’optimisation de la mesure du signal d’ionisation. L'influence de la grille de Frisch sur le signal mesuré a été particulièrement étudiée. Les premières preuves de la reconstruction Compton en utilisant une source de ²²Na (β+, Eγ = 1.274 MeV) sont aussi rapportées dans cette thèse et valident la preuve de concept de la faisabilité de l’imagerie 3γ. Les résultats présentés dans cette thèse ont joué un rôle essentiel dans le développement d’une camera Compton au xénon liquide de grandes dimensions pour l’imagerie des petits animaux. Ce nouveau détecteur, appelée XEMIS2, est maintenant en phase de construction. / The work described in this thesis is focused on the characterization and optimization of a single-phaseliquid xenon Compton camera for medical imaging applications. The detector has been conceived to exploit the advantages of an innovative medical imaging technique called 3γ imaging, which aims to obtain aprecise 3D location of a radioactive source with high sensitivity and an important reduction of the dose administered to the patient. The 3γ imaging technique is based on the detection in coincidence of 3gamma rays emitted by a specific (+β, γ) emitter radionuclide,the 44Sc. A first prototype of a liquid xenon Compton camera has been developed by Subatech laboratory within the XEMIS (Xenon Medical Imaging System) project, to proof the feasibility of the 3γ imaging technique. This new detection framework is based on an advanced cryogenic system and an ultra-low noise front-end electronics operating at liquid xenon temperature. This work has contributed to the characterization of the detector response and the optimization of the ionization signal extraction. A particular interest has been given to the influence of the Frisch grid on the measured signals. First experimental evidences of the Compton cone reconstruction using asource of ²²Na (β+, Eγ = 1.274 MeV) are also reported in this thesis, which demonstrate the proof of concept of the feasibility of the 3γ imaging. The results reported in this thesis have been essential for the development of a larger scale liquid xenon Compton camera for small animal imaging. This new detector, called XEMIS2, is now in phase of construction.

De nombreuses mesures cosmologiques et astrophysiques tendent à montrer que notre galaxie serait englobée par un halo de matière sombre non-baryonique. La détection directionnelle vise à mesurer la direction du recul nucléaire issu d'une interaction avec une particule de matière sombre. Cela permettrait de mettre en évidence la forte dépendance angulaire de la distribution de reculs due à la rotation du système solaire autour du centre galactique. Cette thèse aborde la détection directionnelle par une approche multi-thématique : phénoménologie, expérimentale et analyse de données. L'objectif des études phénoménologiques est de montrer l'apport d'un détecteur directionnel en terme de recherche de matière sombre. Grâce au développement de méthodes statistiques dédiées, on montre qu'un détecteur tel que celui proposé par la collaboration MIMAC, devrait permettre de découvrir la matière sombre avec une grande significance jusqu'à des sections efficaces 2 à 3 ordres de grandeur en dessous des limites actuelles. La mise en place d'une méthodologie d'analyse de données directionnelles constitue un second objectif de cette thèse car la reconstruction 3D des traces mesurées est un point clef de cette nouvelle stratégie de détection. On présente ainsi une nouvelle méthode d'analyse basée sur une approche par vraisemblance, permettant d'optimiser l'estimation des paramètres de chaque événement mesuré: position dans le détecteur et direction. Dans le cadre de la discrimination du bruit de fond électronique, on a mis en place une étude basée sur la topologie de la trace et utilisant une analyse par arbres de décision boostés qui nous permet d'obtenir des facteurs de rejet environ 20 fois supérieurs à ceux obtenus avec des analyses séquentielles. Du point de vue expérimental, on présente une méthode originale de la mesure de vitesse de dérive des électrons permettant d'obtenir des incertitudes de l'ordre du pourcent et de contraindre simultanément les coefficients de diffusion longitudinale. On termine enfin sur l'analyse des données obtenues auprès du champ de neutrons AMANDE permettant de valider la stratégie de détection du projet MIMAC. / A large number of cosmological and astrophysical measurements supports the fact that our galaxy should be immersed in a halo of non-baryonic dark matter. Directional detection aims at measuring the direction of recoiling nucleus following an elastic scattering with a Dark Matter particle. This should allow us to show the expected strong angular dependence of the recoil distribution due to the rotation of the Solar System around the galactic center. This thesis presents a comprehensive study of directional detection following three different aspects: phenomenology, experimental and data analysis. The goal of the phenomenological studies is to explore the interest of directional detection in terms of galactic dark matter search. With the use of dedicated statistical tools we show that a detector, as the one proposed by the MIMAC collaboration, should be able to discover dark matter with a high significance down to cross sections 2 to 3 orders of magnitude below current limits. Setting up a new strategy of data analysis is a second goal of this thesis as an efficient 3D track reconstruction is compulsory to achieve an accurate directional detection of dark matter. We present a new method based on a likelihood approach aiming at the optimisation of the estimation of the parameters of each measured track: position in the detector volume and direction. In the context of reducing the electronic background, we present a method based on the analysis of the track topology using a boosted decision tree algorithm which enhances the rejection power by a factor 20 with respect to a sequential analysis. In the context of experimental measurement, we present a new method dedicated to the measurement of the electron drift velocity with uncertainties of the order of the percent and constraining the longitudinal diffusion coefficients. Eventually, we discuss the results of a data analysis obtained during an acquisition using a neutron field which validate the detection strategy of the MIMAC experiment.

Le collisionneur linéaire international (ILC) est prévu pour être le prochain grand projet de la physique des hautes énergies. ILC est proposé avec deux détecteurs, International Large Detector (ILD), et Silicon Detector (SID). Cette thèse s’est déroulée dans le cadre de l'ILD. L'un des principaux composants du détecteur ILD est la chambre à projection temporelle (TPC). Cette thèse se concentre sur le développement de la lecture de la TPC, basée sur l'intégration des détecteurs de gaz Micro-pattern (Micromegas) et de puces CMOS pixels ("Timepix"). Ce nouveau type de dispositif est appelé "Ingrid". Les exigences principales pour "Ingrid" sont d’atteindre la sensibilité aux électrons uniques et d’obtenir une très haute résolution spatiale (~ 30 µm). Avec une TPC, on reconstruit les traces en utilisant le profil 2D des charges sur la plaque a l’extrémité de la TPC et la troisième coordonnée est dérivée du temps de dérive. Dans le cadre de cette thèse, une mini-TPC a été construite a Saclay dans le but de tester plusieurs prototypes de détecteurs "Ingrid". En outre, un système compose de 8 puces nommé "Octopuce" a été construit pour développer des algorithmes de reconstruction de traces. Nous avons effectué plusieurs mesures à l'aide de source radioactive à Saclay. Par ailleurs, de grands modules ont été testés avec un prototype de grande TPC (LP) sur un faisceau de test à DESY. Les résultats obtenus avec deux modules différents ont été présentés et les résultats sont en bon accord avec la prédiction théorique. La présence de la matière noire fournit une bonne indication d'apparition de nouveaux phénomènes a proximité de l'échelle électrofaible, et l'hypothèse populaire d’existence des WIMP doit être testé. Comme les couplages des WIMP aux différentes espèces de particules du modèle standard sont a priori inconnus, la recherche de la production de WIMP en collisions e+e- est complémentaire à la production dans les collisions pp ou a la détection directe de WIMPs primordiaux par leur diffusion sur des nucléons. Dans ce travail, nous étudions possibilité de découverte (ou l'exclusion) de production de paires de WIMPs avec l’ILC. Dans ce processus, un unique photon est rayonne dans l'état initial et une énergie manquante est requise. Nous montrons que l’ILC peut découvrir cette signature, même si l'annihilation en paires électron-positon contribue faiblement au taux d’annihilation de la matière noire dans l'univers primordial. Nous avons traduit la sensibilité en terme d’échelles de masse pour différents types d’opérateurs effectifs et montré que la masse et les couplages des WIMPs peuvent être mesurés avec une précision de l’ordre de 1% si leur détection est avérée. En outre, des études de production de WIMPs avec l’ILC sont complémentaires aux études avec des états finaux mono-X au LHC, car ils testent le couplage WIMP-lepton. Au LHC, le couplage WIMP-proton est testé a une l'échelle de 1 TeV. Avec l’ILC, en utilisant une luminosité intégrée de 500 fb⁻¹, une énergie dans le centre de masse de √s = 500 GeV et avec des faisceau non polarisés, une limite pour l’échelle sur l'interaction de contact Λ de l’ordre de 2 TeV est accessible. De plus, les configurations de polarisation appropriées permettent d'améliorer la sensibilité pour les recherches de matière noire à l’ILC, en supposant que le couplage des paires de WIMP aux électrons et aux positons dépend du choix de l'opérateur. / The International Linear Collider (ILC) is planned to be the next major project in the High Energy Physics. ILC is proposed to have two detectors, namely International Large Detector (ILD), and Silicon Detector (SiD). This thesis is done in the framework of the ILD. One of the main components of the ILD detector is the Time Projection Chamber (TPC). This PhD thesis concentrates on the development of TPC readout, based on integration of the Micro-pattern gas detectors (Micromegas) and CMOS pixel chips ("Timepix"). This new type of device is named "InGrid". Main requirements for "InGrid" is to achieve sensitivity to single electrons and a very high spatial resolution (~30 μm). In TPC one reconstructs tracks using 2D-charge profile on the TPC endplate and the third coordinate is derived from the drift time information. In Saclay mini-TPC was built. Using this mini-TPC, several prototype "Ingrid" detectors have been tested in the course of this PhD. In addition, 8-chips system named “Octopuce” was built to develop track reconstruction algorithms. We have performed several measurements using laboratory radioactive source in Saclay. In addition, the large modules were tested at a Large TPC Prototype (LP) in a test beam area at DESY. Results with two different modules were presented. Obtained results well agreed with theoretical prediction. The existence of Dark Matter provides a strong indication for the appearance of new phenomena near the electroweak scale, and the popular WIMP hypothesis is out there to be tested. Since the couplings of WIMPs to different species of Standard Model particles are a priori unknown, the investigation of WIMP production in e+e- collisions is fundamentally complementary to production in pp collisions or direct detection of primordial WIMPs scattering on nucleons. In this work we investigate the discovery (or exclusion) reach of the ILC based on the production of a pair of WIMPs, which recoils against an energetic photon from initial state radiation. We show that the ILC can discover this signature even if annihilation to electrons provides only a small fraction of the total dark matter annihilation rate in the early universe. We translated the sensitivity into mass scales of various effective operators and showed that the WIMPs mass and couplings can be measured at the percent level in case of an observation. Furthermore, WIMPs studies on ILC are complementary to current LHC in the mono-X final states, because they test WIMP-lepton coupling. LHC studies WIMP-proton coupling at the scale of 1 TeV. ILC could reach limits up to 2 TeV on the contact interaction scale Λ for the vector operator by using an integrated luminosity at 500 fb⁻¹, at the center-of-mass √s = 500 GeV with unpolarized beams. Moreover, proper polarization configurations allows to improve sensitivity for the Dark Matter searches at the ILC, assuming WIMPs pair couple differently to electron and positron for different operators.

A aplicação de ar quente em videiras foi primeiramente realizada na fazenda do Sr. Florenzo Lazo, localizada no Chile, onde havia a necessidade de combater os efeitos negativos das freqüentes geadas que resultava em severos danos à lavoura. Por este motivo o Sr. Florenzo inventou uma máquina que aplicava ar quente com baixa umidade e tinha por objetivo dispersar o ar frio proveniente das geadas. Após certo tempo, foi observado pelo produtor que no local onde a máquina havia operado com maior frequência as plantas apresentavam-se com uma coloração mais escura e com sinais de maior vitalidade. Seguindo estas observações, relacionamos estes efeitos a um possível aumento nos fito-hormônios relacionados ao estresse vegetal e à SAR (Systemic Resistence Adquired), como o ácido salicílico (AS), ácido jasmônico (AJ) e ácido abscísico (ABA), além de fazer uma correlação com alguns resultados de pós-colheita importantes para a comercialização, como: Sólidos solúveis, firmeza e coloração. Para isso foi montado um experimento que foi conduzido em duas parcelas, sendo uma com tratamento TPC e outra apenas com o tratamento convencional com distância padronizada em 3,2 metros entre linhas por 2,0 metros entre planta. As amostras eram coletadas diariamente e devidamente acondicionadas. Ao final da safra, as amostras foram transportadas para o laboratório de estresse e neurofisiologia da universidade de São Paulo (LEPSE), onde foram novamente armazenadas em um Ultra-freezer - 86ºC. As analises fisiológicas de pós-colheita foram realizadas no departamento de pós-colheita da universidade de São Paulo onde foram analisados os teores de sólidos solúveis, coloração e firmeza das bagas de uva. As amostras de folhas foram maceradas e uniformizadas no LEPSE e enviadas para o laboratório de ecotoxicologia do Centro de Energia Nuclear na Agricultura (CENA) onde foram mensurados os teores dos fito-hormônios pelo método de espectrometria de massa. Para ambas as analises foram feitos testes estatísticos utilizando o programa SAS®. Não houve alteração de SS e firmeza entre os dois tratamentos para as características fisiológicas de póscolheita. Entretanto foi notado uma redução na coloração avermelhada para os cachos tratados com TPC seguindo o sistema de colorimetria proposto pelo CIE. Não houve alterações significantes para as variáveis ABA, AJ e AS para o efeito tratamento e para a analise de correlação. Entretanto notou-se significância entre o efeito dias para as variáveis ABA e AJ. Não foi notada significância para o efeito dias para a variável AS. Por se tratar de um estresse rápido, a TPC parece não causar estresse imediato nas plantas, entretanto notou-se indução de estresse ao longo do tempo, possivelmente devido à resposta lenta de ABA que aparentemente está envolvida com RNA e à síntese de proteínas S e R- ABA que são igualmente efetivas. Já para o AJ sugere-se que houve a produção de H2O2 por derivados de oligogalacturonideos, liberados por ação da enzima poligalacturonase, e um segundo mensageiro que ativam genes defensivos (genes tardios). O aumento na biossíntese do ABA e do AJ parece ter suprimido genes envolvidos na biossíntese do AS. / The application of hot air in grapevines was first held on the farm of Mr. Florenzo Lazo, located in Chile, to combat the negative effects of frequent frosts that resulted in severe damage to the crop. For this reason Mr. Florenzo invented a machine that applied hot air with low humidity and aimed to disperse the cold air from the frost. After a while, it was observed by the producer that where the machine had operated more frequently plants showed up with a darker and more signs of vitality. Following these observations, these effects relate to a possible increase in phytohormones related to plant stress and SAR (Systemic Resistance Adquired), such as salicylic acid (AS), jasmonic acid (AJ) and abscisic acid (ABA), besides making a correlation with results of some important postharvest for marketing, such as soluble solids, firmness and color. For this experiment was created that was conducted in two installments, the first one was treated with TPC and second one was applied only conventional treatment with standardized distance of 3.2 meters between lines by 2.0 meters between plant . The samples were collected daily and properly packed. At the end of the season, samples were transported to the laboratory stress and neurophysiology from the University of São Paulo (LEPSE), where they were again stored in an Ultra-freezer - 86 degrees. The physiological analyses of post-harvest were performed at the Department of Postharvest in University of Sao Paulo where we analyzed the levels of soluble solids, firmness and color in grape berries. The leaf samples were uniform macerated at LEPSE and sent to the laboratory of ecotoxicology in the Center for Nuclear Energy in Agriculture (CENA) where we measured the levels of the phytohormones by the method of mass spectrometry. For both analyzes were performed statistical tests using SAS ® program. There wasn`t change between the two treatments on physiological post-harvest characteristics. There was no change of SS and firmly between the two treatments for the physiological of post-harvest characteristics. However it was noted a reduction in red color for bunches treated with TPC following the colorimetry system by CIE. There were no significant changes to the variables ABA, AJ and AS for the treatment effect and to analyze the correlation. However significance was noted between the effect variables ABA days and AJ. No significant effect was noted for days variable for AS. Since it is a stress fast TPC does not seem to cause immediate stress in plants but it was noticed induction of stress over time, possibly due to slow response to ABA which apparently is involved in the synthesis of RNA and proteins S and R-ABA that are equally effective. As for AJ suggests that there was the production of H2O2 by derivatives of oligogalacturonides, released by action of the enzyme polygalacturonase, and a second messenger that activates defensive genes (late genes). The increase in ABA biosynthesis and AJ appears to have deleted genes involved in the biosynthesis of AS.

A aplicação de ar quente em videiras foi primeiramente realizada na fazenda do Sr. Florenzo Lazo, localizada no Chile, onde havia a necessidade de combater os efeitos negativos das freqüentes geadas que resultava em severos danos à lavoura. Por este motivo o Sr. Florenzo inventou uma máquina que aplicava ar quente com baixa umidade e tinha por objetivo dispersar o ar frio proveniente das geadas. Após certo tempo, foi observado pelo produtor que no local onde a máquina havia operado com maior frequência as plantas apresentavam-se com uma coloração mais escura e com sinais de maior vitalidade. Seguindo estas observações, relacionamos estes efeitos a um possível aumento nos fito-hormônios relacionados ao estresse vegetal e à SAR (Systemic Resistence Adquired), como o ácido salicílico (AS), ácido jasmônico (AJ) e ácido abscísico (ABA), além de fazer uma correlação com alguns resultados de pós-colheita importantes para a comercialização, como: Sólidos solúveis, firmeza e coloração. Para isso foi montado um experimento que foi conduzido em duas parcelas, sendo uma com tratamento TPC e outra apenas com o tratamento convencional com distância padronizada em 3,2 metros entre linhas por 2,0 metros entre planta. As amostras eram coletadas diariamente e devidamente acondicionadas. Ao final da safra, as amostras foram transportadas para o laboratório de estresse e neurofisiologia da universidade de São Paulo (LEPSE), onde foram novamente armazenadas em um Ultra-freezer - 86ºC. As analises fisiológicas de pós-colheita foram realizadas no departamento de pós-colheita da universidade de São Paulo onde foram analisados os teores de sólidos solúveis, coloração e firmeza das bagas de uva. As amostras de folhas foram maceradas e uniformizadas no LEPSE e enviadas para o laboratório de ecotoxicologia do Centro de Energia Nuclear na Agricultura (CENA) onde foram mensurados os teores dos fito-hormônios pelo método de espectrometria de massa. Para ambas as analises foram feitos testes estatísticos utilizando o programa SAS®. Não houve alteração de SS e firmeza entre os dois tratamentos para as características fisiológicas de póscolheita. Entretanto foi notado uma redução na coloração avermelhada para os cachos tratados com TPC seguindo o sistema de colorimetria proposto pelo CIE. Não houve alterações significantes para as variáveis ABA, AJ e AS para o efeito tratamento e para a analise de correlação. Entretanto notou-se significância entre o efeito dias para as variáveis ABA e AJ. Não foi notada significância para o efeito dias para a variável AS. Por se tratar de um estresse rápido, a TPC parece não causar estresse imediato nas plantas, entretanto notou-se indução de estresse ao longo do tempo, possivelmente devido à resposta lenta de ABA que aparentemente está envolvida com RNA e à síntese de proteínas S e R- ABA que são igualmente efetivas. Já para o AJ sugere-se que houve a produção de H2O2 por derivados de oligogalacturonideos, liberados por ação da enzima poligalacturonase, e um segundo mensageiro que ativam genes defensivos (genes tardios). O aumento na biossíntese do ABA e do AJ parece ter suprimido genes envolvidos na biossíntese do AS. / The application of hot air in grapevines was first held on the farm of Mr. Florenzo Lazo, located in Chile, to combat the negative effects of frequent frosts that resulted in severe damage to the crop. For this reason Mr. Florenzo invented a machine that applied hot air with low humidity and aimed to disperse the cold air from the frost. After a while, it was observed by the producer that where the machine had operated more frequently plants showed up with a darker and more signs of vitality. Following these observations, these effects relate to a possible increase in phytohormones related to plant stress and SAR (Systemic Resistance Adquired), such as salicylic acid (AS), jasmonic acid (AJ) and abscisic acid (ABA), besides making a correlation with results of some important postharvest for marketing, such as soluble solids, firmness and color. For this experiment was created that was conducted in two installments, the first one was treated with TPC and second one was applied only conventional treatment with standardized distance of 3.2 meters between lines by 2.0 meters between plant . The samples were collected daily and properly packed. At the end of the season, samples were transported to the laboratory stress and neurophysiology from the University of São Paulo (LEPSE), where they were again stored in an Ultra-freezer - 86 degrees. The physiological analyses of post-harvest were performed at the Department of Postharvest in University of Sao Paulo where we analyzed the levels of soluble solids, firmness and color in grape berries. The leaf samples were uniform macerated at LEPSE and sent to the laboratory of ecotoxicology in the Center for Nuclear Energy in Agriculture (CENA) where we measured the levels of the phytohormones by the method of mass spectrometry. For both analyzes were performed statistical tests using SAS ® program. There wasn`t change between the two treatments on physiological post-harvest characteristics. There was no change of SS and firmly between the two treatments for the physiological of post-harvest characteristics. However it was noted a reduction in red color for bunches treated with TPC following the colorimetry system by CIE. There were no significant changes to the variables ABA, AJ and AS for the treatment effect and to analyze the correlation. However significance was noted between the effect variables ABA days and AJ. No significant effect was noted for days variable for AS. Since it is a stress fast TPC does not seem to cause immediate stress in plants but it was noticed induction of stress over time, possibly due to slow response to ABA which apparently is involved in the synthesis of RNA and proteins S and R-ABA that are equally effective. As for AJ suggests that there was the production of H2O2 by derivatives of oligogalacturonides, released by action of the enzyme polygalacturonase, and a second messenger that activates defensive genes (late genes). The increase in ABA biosynthesis and AJ appears to have deleted genes involved in the biosynthesis of AS.

<p>  </p> <p>This dissertation explores multimodal composing strategies enacted by technical and professional communication (TPC) writers during and post-COVID-19 period. The researcher presents an investigation into a course unit project and pedagogical approach framed around the idea of multimodal composition in an upper-division professional writing class with transnational students majoring in management, economics, health science, aviation technology, mathematics, computer engineering, accounting, consumer science, biology, and agronomy in a large research university in the Midwest. This study advocates a multimodal approach to teaching writing in its expanded sense with multimodal career unit project assignments in multiple media and modes, including resumes/CVs, personal statements, LinkedIn profiles, video profiles/resumes, job position analyses, and rhetorical and mode analyses. This project presents implications for instructors of technical and professional communicators who are aiming to develop and update their curricula and teaching pedagogies situated in multiple modes across global audiences, for multiple purposes, and in a variety of media.</p>

Made available in DSpace on 2014-06-12T17:38:30Z (GMT). No. of bitstreams: 2 arquivo6838_1.pdf: 8328507 bytes, checksum: d656bce5f5df0978588e23edcc6f1957 (MD5) license.txt: 1748 bytes, checksum: 8a4605be74aa9ea9d79846c1fba20a33 (MD5) Previous issue date: 2008 / Companhia Hidro Elétrica do São Francisco / Os Transformadores de Potencial Capacitivos (TPC) fornecem através dos seus enrolamentos secundários as informações do sinal de tensão do sistema elétrico de potência para controle, proteção e medição. Falhas destes equipamentos podem causar saídas intempestivas de linhas de transmissão (LT) que resultam em severas penalidades impostas pela regulamentação do setor elétrico. Este fato requer agilidade da manutenção para recompor a função transmissão no menor tempo possível, bem como medidas preventivas no sentido de reduzir os desligamentos não programados. Neste contexto, estudos têm sido realizados para modelar os TPC voltados para análises de transitórios eletromagnéticos. Diante do estado da arte, o trabalho mostra que nas manobras de abertura da LT podem ocorrer amplificações da tensão nos secundários do TPC por um tempo sustentado, fruto da interação transitória que causa solicitações térmicas e dielétricas impostas aos componentes do mesmo. Esta interação é influenciada pelo projeto do equipamento e pelo grau de compensação da LT, comprovados neste estudo através de levantamento da resposta em frequência, ensaios nos componentes de diferentes projetos de TPC e simulações digitais. Além disto, o trabalho apresenta registros oscilográficos do sistema de transmissão da Companhia Hidro Elétrica do São Francisco como ilustração da existência deste fenômeno. Destaca-se ainda que a expansão do sistema interligado nacional pode exigir maior frequência de manobras das LT, o que implica em majoração dos efeitos mencionados