The key task for a search engine advertising system is, for each query that the search engine receives, to choose what advertisement should be displayed, and in what order. This ranking order has a strong impact on the revenue the search engine receives from the ads. Meanwhile, showing the user an advertisement that they prefer to click on improves user satisfaction. Therefore, it is reasonable to set up click-through rate (CTR) as a weighted ranking criteria. In this project, we aim to develop a model capable of accurately predicting CTR of ads in the system. For ads that have been displayed repeatedly, this is empirically measurable, but for new ads, other means must be used. Combining logistic regression model with L1 regularization we are able to predict CTR for new ads based on self-defined features. The ultimate goal is to improve the convergence and performance of our advertising system, consequently increasing both revenue and user satisfaction. Second part of this report is about a study on poisson factorization recommender evaluation. As recommender systems become more and more popular, many approaches have been suggested to evaluate the performance of traditional recommenders based on Gaussian distribution. However, few evaluating approaches were designed for poisson factorization recommender. This study checked some most common evaluation methods and discussed about their appropriateness in poisson factorization recommender evaluation. / text

The thesis deals about banner advertisement. After brief introduction, theoretical basis describes how did banner advertisement go throughout the timeline, what are the possibilities of banner advertisement, which technologies can be used for proper banner advertisement, how is it measured, etc. In practical part of thesis a global company is introduced and there are analyzed ways how it uses banners in its web presentation. In final part a research is made to point out the importance of various factors effecting the efficiency of banner advertising. In conclusion author summarizes findings and tries to give hints how to use powers of effective advertising in bussinnes.

<p>Copper was first released into the environment as the result of the mass generation of oxygen from photosynthetic bacteria roughly 2.7 billion years ago. While it proved to be poisonous to early life on Earth, those that met the evolutionary challenge utilized the metal as a cofactor in enzymes to perform biochemically significant functions, while controlling intracellular levels of copper with a sophisticated network of trafficking proteins. Proteins and enzymes that utilize copper as a cofactor have evolved significantly different coordination environments than copper trafficking proteins, as a result of the different functions they perform. Of particular interest was characterizing the unique Cu(I) binding events observed in some of these proteins, the extracellular N-terminal regions of eukaryotic high affinity copper transport proteins (Ctr), and the bacterial periplamsic CusF protein of the CusFBCA Cu(I)/Ag(I) efflux pathway. </p><p>Model peptides corresponding to the methionine rich binding motifs (Mets motifs) were characterized in terms of Cu(I) binding affinity, stoichiometry, and metal specificity, via an ascorbic acid oxidation assay and electrospray ionization mass spectrometry. Metal induced structural features and coordination environments were elucidated with NMR, CD and X-ray spectroscopy. A series of peptides was also examined to infer the relative Cu(I) binding affinities, and susceptibility to oxidation, of methionine, histidine, cysteine residues found in copper binding motifs. The resistance of Cu+ specific peptides to metal catalyzed oxidation is also described. Attempts were also made to model the Cu(I)/Ag(I) tryptophan cation-&#960; interaction observed in CusF.</p> / Dissertation

Die Langzeitsicherheitsanalyse für ein Endlager für nukleare Abfälle bedarf einer eingehenden Beschreibung der Mobilität von Radionukliden im Nah- und Fernfeld des Endlagers. Da extrem lange Zeiträume von bis zu einer Million Jahren abgebildet werden müssen, muss diese Beschreibung auf einem molekularen Prozessverständnis beruhen. Nur dann ist eine unbegrenzte zeitliche Extrapolation zulässig. Die wichtigsten Rückhalteprozesse finden an der Wasser/Mineralgrenzfläche statt, wobei in einem realen Endlager sehr viele primäre und sekundäre Mineralphasen vorhanden sind, mit denen die Radionuklide wechselwirken können. Zudem stehen eine Vielzahl verschiedener Reaktionsmechanismen zur Verfügung – innersphärische oder außersphärische Sorption, struktureller Einbau, Oberflächenfällung etc. – die sich hinsichtlich ihrer Rückhaltefähigkeit deutlich unterscheiden. Somit muss auf hochsensitive Methoden zurückgegriffen werden, die in der Lage sind, selektiv Informationen über die relevanten Radionuklide innerhalb der Grenzschicht zu liefern. Die in dieser Arbeit hauptsächlich verwendeten Methoden, die zeitaufgelöste Laser-induzierte Fluoreszenzspektroskopie (TRLFS), und die Oberflächenröntgenbeugungsmethoden crystal truncation rod (CTR) Messung und resonant anomalous X-ray reflectivity (RAXR), haben sich als effiziente Werkzeuge zur Ermittlung struktureller und Speziationsdaten erwiesen. So konnte im Rahmen dieser Arbeit die Wechselwirkung der Radionuklide U, Pu, Am und Cm mit verschiedenen Mineralphasen aufgeklärt, sowie die Abhängigkeit dieser Reaktionen von der Lösungszusammensetzung beschrieben werden.:1 Einleitung 9 1.1 Zeitaufgelöste laser-induzierte Fluoreszenzspektroskopie 12 1.2 Oberflächenröntgenbeugung 18 2 Spektroskopische Charakterisierung von Einbauprozessen 21 2.1 Biswas S, Steudtner R, Schmidt M, McKenna C, Vintró LL 25 Twamley B, et al. An investigation of the interactions of Eu3+ and Am3+ with uranyl minerals: implications for the storage of spent nuclear fuel. Dalton Transactions. 2016; 45(15):6383-93. 2.2 Schmidt M, Heck S, Bosbach D, Ganschow S, Walther 36 C, Stumpf T. Characterization of powellite-based solid solutions by site-selective time resolved laser fluorescence spectroscopy. Dalton Transactions. 2013;42(23):8387 - 93. 2.3 Hellebrandt SE, Hofmann S, Jordan N, Barkleit A, Schmidt M. 43 Incorporation of Eu(III) into Calcite under recrystallization conditions. Scientific Reports. 2016;6:33137. 2.4 Johnstone EV, Hofmann S, Cherkouk A, Schmidt M. 53 Study of the Interaction of Eu3+ with Microbiologically Induced Calcium Carbonate Precipitates using TRLFS. Environmental Science & Technology. 2016;50(22):12411-20. 3 Oberflächeninduzierte Kondensationsreaktionen 63 3.1 Lee SS, Schmidt M, Fister TT, Nagy KL, Sturchio NC, Fenter P. 65 Structural Characterization of Aluminum (Oxy)hydroxide Films at the Muscovite (001)–Water Interface. Langmuir. 2016; 32(2):477-86. 3.2 Hellebrandt S, Lee SS, Knope KE, Lussier AJ, Stubbs JE, Eng 75 PJ, et al. Cooperative effects of adsorption, reduction, and polymerization observed for hexavalent actinides on the muscovitebasal plane. Langmuir. 2016; 32(41):10473-82.6 3.3 Schmidt M, Lee SS, Wilson RE, Knope KE, Bellucci F, Eng 85 PJ, et al. Surface-Mediated Formation of Pu(IV) Nanoparticles at the Muscovite-Electrolyte Interface. Environmental Science & Technology. 2013;47(24):14178-84. 4 Elektrolyteffekte auf Oberflächenprozesse 92 4.1 Lee SS, Schmidt M, Laanait N, Sturchio NC, Fenter P. 94 Investigation of Structure, Adsorption Free Energy, and Overcharging Behavior of Trivalent Yttrium Adsorbed at the Muscovite (001)–Water Interface. The Journal of Physical Chemistry C. 2013;117(45):23738-49. 4.2 Schmidt M, Hellebrandt S, Knope KE, Lee SS, Stubbs JE, 106 Eng PJ, et al. Effects of the Background Electrolyte on Th(IV) Sorption to Muscovite Mica. Geochimica et Cosmochimica Acta. 2015;165:280-93. 4.3 Hofmann S, Voïtchovsky K, Schmidt M, Stumpf T. Trace 120 concentration – Huge impact: Nitrate in the calcite/Eu(III) system. Geochimica et Cosmochimica Acta. 2014;125:528-38. 4.4 Hofmann S, Voïtchovsky K, Spijker P, Schmidt M, Stumpf 131 T. Visualising the molecular alteration of the calcite (104)–water interface by sodium nitrate. Scientific Reports. 2016; 6:21576. 5 Schlussfolgerungen 142 Literatur 146 / The safety assessment of a nuclear waste disposal site requires the accurate description of the radionuclides’ mobility in the near and far field of the site. This description must rely on molecular level understanding of the occurring processes to allow extrapolation for time frames of up to one million years. The most important retention mechanisms take place at the water/mineral interface. A disposal site will contain a large number of mineral phases, both as primary and secondary minerals. Moreover, a large number of potential reaction pathways is conceivable, and must be investigated: inner and outer sphere sorption, structural incorporation, surface precipitation, etc. As these mechanisms will differ significantly in their retention potential, it is crucial to be able to differentiate between them. Hence, the need arises for analytical techniques capable of providing selective information about radionuclides at the water/mineral interface. This work employs time-resolved laser-induced fluorescence spectroscopy (TRLFS), as well as the surface X-ray diffraction techniques crystal truncation rod (CTR) measurements and resonant anomalous X-ray reflectivity (RAXR) as efficient tools to obtain both structural and speciation data from these systems. Following this approach, the interaction of the radionuclides U, Pu, Am, and Cm with various mineral phases could be elucidated, while also characterizing the dependence of these reactions on the composition of the aqueous solution.:1 Einleitung 9 1.1 Zeitaufgelöste laser-induzierte Fluoreszenzspektroskopie 12 1.2 Oberflächenröntgenbeugung 18 2 Spektroskopische Charakterisierung von Einbauprozessen 21 2.1 Biswas S, Steudtner R, Schmidt M, McKenna C, Vintró LL 25 Twamley B, et al. An investigation of the interactions of Eu3+ and Am3+ with uranyl minerals: implications for the storage of spent nuclear fuel. Dalton Transactions. 2016; 45(15):6383-93. 2.2 Schmidt M, Heck S, Bosbach D, Ganschow S, Walther 36 C, Stumpf T. Characterization of powellite-based solid solutions by site-selective time resolved laser fluorescence spectroscopy. Dalton Transactions. 2013;42(23):8387 - 93. 2.3 Hellebrandt SE, Hofmann S, Jordan N, Barkleit A, Schmidt M. 43 Incorporation of Eu(III) into Calcite under recrystallization conditions. Scientific Reports. 2016;6:33137. 2.4 Johnstone EV, Hofmann S, Cherkouk A, Schmidt M. 53 Study of the Interaction of Eu3+ with Microbiologically Induced Calcium Carbonate Precipitates using TRLFS. Environmental Science & Technology. 2016;50(22):12411-20. 3 Oberflächeninduzierte Kondensationsreaktionen 63 3.1 Lee SS, Schmidt M, Fister TT, Nagy KL, Sturchio NC, Fenter P. 65 Structural Characterization of Aluminum (Oxy)hydroxide Films at the Muscovite (001)–Water Interface. Langmuir. 2016; 32(2):477-86. 3.2 Hellebrandt S, Lee SS, Knope KE, Lussier AJ, Stubbs JE, Eng 75 PJ, et al. Cooperative effects of adsorption, reduction, and polymerization observed for hexavalent actinides on the muscovitebasal plane. Langmuir. 2016; 32(41):10473-82.6 3.3 Schmidt M, Lee SS, Wilson RE, Knope KE, Bellucci F, Eng 85 PJ, et al. Surface-Mediated Formation of Pu(IV) Nanoparticles at the Muscovite-Electrolyte Interface. Environmental Science & Technology. 2013;47(24):14178-84. 4 Elektrolyteffekte auf Oberflächenprozesse 92 4.1 Lee SS, Schmidt M, Laanait N, Sturchio NC, Fenter P. 94 Investigation of Structure, Adsorption Free Energy, and Overcharging Behavior of Trivalent Yttrium Adsorbed at the Muscovite (001)–Water Interface. The Journal of Physical Chemistry C. 2013;117(45):23738-49. 4.2 Schmidt M, Hellebrandt S, Knope KE, Lee SS, Stubbs JE, 106 Eng PJ, et al. Effects of the Background Electrolyte on Th(IV) Sorption to Muscovite Mica. Geochimica et Cosmochimica Acta. 2015;165:280-93. 4.3 Hofmann S, Voïtchovsky K, Schmidt M, Stumpf T. Trace 120 concentration – Huge impact: Nitrate in the calcite/Eu(III) system. Geochimica et Cosmochimica Acta. 2014;125:528-38. 4.4 Hofmann S, Voïtchovsky K, Spijker P, Schmidt M, Stumpf 131 T. Visualising the molecular alteration of the calcite (104)–water interface by sodium nitrate. Scientific Reports. 2016; 6:21576. 5 Schlussfolgerungen 142 Literatur 146

Sammanfattning Bakgrund - Dagens processorer börjar närma sig gränsen för hur höga klockfrekvenser de kan köras i. Detta har lett till att processorer har fått fler kärnor för att kunna exekvera flera processer parallellt med flertrådade applikationer. Det finns dock ofta en stor mängd oanvänd beräkningskraft under långa perioder då datorn är igång som ligger i grafikprocessorn, GPU. Då en GPU kan köra tusentals många fler trådar på samma gång än en CPU har ramverk för att göra mer generella beräkningar på GPU utvecklats, dessa kallas för GPGPU-ramverk. Då varje kärna på en GPU inte är lika stark som på en CPU ligger vinsten i att använda algoritmer som går bra att parallellisera. En sådan algoritm är krypteringsalgoritmen AES som är en av de säkraste och vanligaste krypteringsalgoritmerna som används idag. Syfte – Med hjälp av GPU-accelerering kan man kryptera med AES snabbare än med en traditionell CPU-lösning. För att göra GPU-accelereringen så effektiv som möjligt undersöker detta examensarbete vilken AES-metod samt vilket GPGPU-ramverk man bör välja. Metod – För att undersöka vilken/vilka AES-metoder samt vilka GPGPU-ramverk som var lämpliga att använda för denna undersökning gjordes två litteraturstudier. Utifrån data som litteraturstudierna gav genomfördes experiment för att jämföra de valda GPGPU-ramverken med den valda AES-metoden som ansågs vara mest lämpliga. Resultat – Från litteraturstudierna kom det fram att OpenCL och CUDA blir de rekommenderade GPGPU-ramverken och att CTR blir den rekommenderade AES-metoden för AES-kryptering med GPGPU-programmering. Utifrån experimenten som genomförts kunde det konstateras att CUDA är ett effektivare GPGPU-ramverk än OpenCL för AES-CTR på det testade grafikkortet, GTX 560. Implikationer – CUDA är snabbare vid större filer för att OpenCL begränsas mer av dataöverföringshastigheten än CUDA på ett GTX 560. Begränsningar – Experimenten genomfördes endast på ett grafikkort från Nvidia. Eftersom Nvidia inte har något intresse i att optimera för andra GPGPU-ramverk så kunde inte testresultaten från OpenCL verifieras med externa verktyg. Detta p.g.a. att Nvidias verktyg inte längre stödjer debugging eller profiling för OpenCL. Nyckelord – Processorer, GPGPU, AES, CTR, OpenCL, CUDA, GPGPU-ramverk / Abstract Background - Processors today are approaching the limit for how high clockfrequences they can run. This has led to that instead of trying to make them run faster they are instead made with multiple cores so they can utilize parallelization by running several threads in parallel. However aside from the CPU there is still the graphics card which has a large amount of unused computing power for long durations of time while the computer is active. While a GPU might not have as quick processors it instead has several thousands of them at the same time than a CPU which have led to the development of GPGPU-frameworks to use that potential parallelization. The profit in this lies in using algorithms and code functions that got high potential parallelization, one of which is the AES encryption algorithm. AES is one of the most widely used encryption algorithms today and also considered to be one of the most secure. Purpose – By using GPGPU-acceleration the encryption speed of AES is higher than by using a traditional CPU approach. To make the GPU-acceleration as effective as possible this study looks into which AES-method and which GPGPU-framework that should be chosen during development. Method – This study makes two literature studies to determine which AES-methods and which GPGPU-frameworks that are viable for GPU-acceleration of AES. Afterwards this study conducts experiments to determine which of these GPGPU-frameworks are the most effective. Findings – The conclusion drawn from the literature study is that the CTR-method among the AES-methods is preferable due to its parallelization potential and high security measures. Among the current GPGPU-frameworks only two frameworks satisfies the criteria determined from the literature study and those are CUDA and OpenCL. From the experiment the conclusion is thereafter drawn that of the two GPGPU-frameworks CUDA is more effective due to the bandwidth limits that OpenCL have compared to CUDA. This conclusion is valid on at least the tested graphics card, GTX 560. Implications – CUDA is faster at larger file sizes than OpenCL due to limited data transfer speed in OpenCL on a GTX 560. Limitations – The experiments were only conducted on one graphics card from Nvidia due to hardware constraints in that CUDA can only be run on Nvidia hardware. Due to this hardware constraint and Nvidia’s lack of support in their tools for debugging and profiling of OpenCL the results from the testing of OpenCL couldn’t be verified using external tools. Keywords – Processor, GPGPU, AES, CTR, OpenCL, CUDA, GPGPU-framework

Com o avanço da internet, novos tipos de negócios surgiram. Por exemplo, o sistema de anúncios online: produtores de sites e diversos outros conteúdos podem dedicar em uma parte qualquer de sua página um espaço para a impressão de anúncios de diversas lojas em troca de um valor oferecido pelo anunciante. É neste contexto que este trabalho se insere. O objetivo principal é o desenvolvimento de algoritmos que preveem a probabilidade que um dado usuário tem de se interessar e clicar em um anúncio a que está sendo exposto. Este problema é conhecido como predição de CTR (do inglês, \"Click-Through Rate\") ou taxa de conversão. Utiliza-se para isto uma abordagem baseada em regressão logística integrada a técnicas de fatoração de matriz que preveem, através da obtenção de fatores latentes do problema, a probabilidade de conversão para um anúncio impresso em dado site. Além disto, testes considerando uma estratégia dinâmica (em função do tempo) são apresentados indicando que o desempenho previamente obtido pode melhorar ainda mais. De acordo com o conhecimento do autor, esta é a primeira vez que este procedimento é relatado na literatura. / With the popularization of the internet, new types of business are emerging. An example is the online marketing system: publishers can dedicate in any given space of theirs websites a place to the printing of banners from different stores in exchange for a fee paid by the advertiser. It\'s in this context that this work takes place. Its main goal will be the development of algorithms that forecasts the probability that a given user will get interested in the ad he or she is seeing and click it. This problem is also known as CTR Prediction Task. To do so, a logistic regression approach is used combined with matrix factorization techniques that predict, through latent factor models, the probability that the click will occur. On top of that, several tests are conducted utilizing a dynamic approach (varying in function of time) revealing that the performance can increase even higher. According to the authors knowledge, this is the first time this test is conducted on the literature of CTR prediction.

Subglottic stenosis (SGS) is a narrowing of the airway in the region of the cricoid cartilage below the vocal folds and above the tracheal rings. Individuals with SGS experience difficulty breathing at rest and during exertion both of which become increasingly difficult with the level of stenosis severity. Some individuals also experience negative voice changes. Individuals whose stenoses significantly impact breathing generally require medical procedures or surgery, either balloon dilation or cricotracheal resection (CTR). CTR has been shown to improve patients' ability to breathe, but it can also result in permanent vocal changes. Alternatively, balloon dilation results in similar breathing improvements but for a relatively short period of time. Many studies have been published on the effectiveness of CTR; however, only a few have examined the effects of CTR on vocal production. The purpose of this study is to quantify the acoustic and auditory-perceptual features of subglottic stenosis and examine possible acoustic and auditory-perceptual changes in voice production following a revised CTR aimed to minimize voice impact in a group of women. A retrospective chart review identified women with idiopathic SGS who received revised CTR at The University of Utah Voice Disorders Center between 2008 and 2014. Presurgical and postsurgical groups included patients with both pre and post recordings (n = 11) as well as patients with only pre (n = 6) or post (n = 9) recordings. Acoustic quantification of voice signal periodicity, as well as cepstral, spectral, and fundamental frequency (F0) analyses were performed. Auditory-perceptual ratings of overall quality and monotonicity were performed. Cross-sectional and pre-post surgery analyses were completed. Aggregate analyses revealed that both pre and posttreatment SGS patients demonstrated voice disorders in the mild to moderate severity range. Pre-post comparisons indicated no significant voice change after surgery. Mean fundamental frequency decreased from 215 Hz (SD = 40 Hz) to 201 Hz (SD = 65 Hz). Voice disorder severity based on the cepstral spectral index of dysphoniaTM for sustained vowels decreased (i.e., improved) from 41 (SD = 41) to 25 (SD = 21) points. Semitone standard deviation (2.2 semitones) was equivalent from pretreatment to posttreatment. Auditory-perceptual ratings demonstrated similar results. These preliminary results indicate that the revised CTR procedure is promising in minimizing adverse voice effects. Future research is needed to determine causative factors for pretreatment voice disorders, as well as to optimize treatments in this population.

Les produits de contraste ultrasonore constituent un véritable apport pour l'imagerie échographique et sont aujourd'hui utilisés en clinique pour l'évaluation de la perfusion cardiaque ou encore la détection de tumeurs. Depuis quelques années, les transducteurs capacitifs micro-usinés (cMUTs) se présentent comme une alternative intéressante aux transducteurs piézoélectriques classiques et offrent certains avantages comme une large bande passante. Nous proposons dans cette thèse d'évaluer le potentiel de cette technologie pour l'imagerie de contraste. Dans un premier temps, notre étude s'est orientée vers l'adaptation des cMUTs à l'imagerie non linéaire. Ensuite, de nouvelles méthodes de détection de contraste, basées sur le comportement spécifique des microbulles, ont été développées pour exploiter les avantages de la technologie cMUT. Comparés aux méthodes conventionnelles, les résultats obtenus montrent une meilleure visualisation des agents de contraste par rapport aux tissus environnants. L'utilisation de cMUTs améliore l'efficacité de ces méthodes démontrant, ainsi, leur intérêt pour l'imagerie de contraste.

The calcitonin gene family of peptides consists of calcitonin (CT), two calcitonin gene related peptides (α-CGRP, β-CGRP), adrenomedullin (ADM), amylin (AMY), three calcitonin receptor activating peptides (CRSP1-3) and intermedin/adrenomedullin2 (IMD). These peptides bind to one of two G protein -coupled receptors, the calcitonin receptor (CTR) or the calcitonin receptor-like receptor (CRLR). The receptor specificity to different ligands is dependent on the formation of a complex with one of three receptor activity-modifying proteins (RAMP1-3). The aim of this study was to analyse effects of this family of peptides on the formation of osteoclasts and bone resorption, and the expression of the receptor components in bone cells. CT inhibited the formation of multinucleated osteoclasts in spleen cell cultures and in bone marrow macrophage cultures (BMM) without affecting a number of genes important for osteoclast differentiation, activity or fusion of osteoclast progenitor cells. All members of the CT family, except ADM, inhibited osteoclastogenesis in BMM. The inhibitory effect seemed to involve activation of both protein kinase A and the exchange protein directly activated by cyclic AMP (Epac) signalling. BMM expressed the CRLR, RAMP1-3 and the receptor component protein (RCP). AMY, ADM, CGRP and IMD, but not CRSP and CT, increased cyclic AMP (cAMP) levels in these cells, indicating the presence of functional receptors. Stimulation of BMM with RANKL gradually increased the levels of CTR mRNA as well as the capacity of the cells to respond to the stimulation by CRSP and CT. The response to stimulation of ADM was, on the contrary, decreased by RANKL. Stimulation of RANKL caused a transiently enhanced CRLR mRNA expression and transiently decreased RAMP1, but did not affect RAMP2, RAMP3, or RCP mRNA. However, RANKL did not affect protein levels of CRLR or RAMP1-3. CT, CGRP, AMY, ADM, IMD and CRSP all down regulated the CTR mRNA, but none of the peptides caused any effects on the expression of CRLR or any of the RAMPs. All members of the CT family, except ADM, rapidly and transiently, inhibited bone resorption in mouse calvarial bones. CT, CGRP, AMY and CRSP also significantly stimulated cAMP formation in the calvaria. cAMP analogues specifically stimulating the PKA or the Epac pathways did not cause inhibition of bone resorption in the calvaria. An unspecific cAMP analogue, stimulating both pathways did, however, cause inhibition. Analyses of an osteoblastic cell line, MC3T3-E1, showed that these cells express the mRNA for CRLR and all three RAMP proteins. In conclusion, the results of this thesis show that all peptides in CT family of peptides, except ADM, inhibit of bone resorption and osteoclast formation and that these effects involve the adenylate cyclase-cAMP pathway. Furthermore, expressions of CRLR and RAMP1-3 mRNA have been demonstrated on osteoclasts, as well as in an osteoblastic cell line.

<p>Copper is an essential trace element required by all aerobic organisms as a co-factor for enzymes involved in normal growth, development and physiology. Ctr1 proteins are members of a highly conserved family of copper importers responsible for copper uptake across the plasma membrane. Mice lacking Ctr1 die during embryogenesis from widespread developmental defects, demonstrating the need for adequate copper acquisition in the development of metazoan organisms via as yet uncharacterized mechanisms. The early lethality of the Ctr1 knockout mouse has made it difficult to study the functions of copper and Ctr1 proteins in metazoan development and physiology. Drosophila melanogaster, a genetically tractable system expresses three Ctr1 genes, Ctr1A, Ctr1B and Ctr1C, and may help to further understand the roles of copper and Ctr1 proteins in metazoan development and physiology. Described here is the characterization of Drosophila Ctr1A. </p><p>Localization studies using an affinity purified anti-Ctr1A peptide antibody show Ctr1A is predominantly expressed at the plasma membrane in whole embryos and in larval tissues. Ctr1A is an essential gene in Drosophila as loss-of-function mutants, generated by imprecise p-element excision arrest at early larval stages of development. Inductively coupled plasma mass spectroscopy (ICP-MS) demonstrated that whole body copper levels are reduced in Ctr1A mutants and consequently, a number of copper-dependent enzyme deficiencies were detected by in vitro enzyme and cell biological assays. Ctr1A maternal and zygotic mutants have a more severe developmental phenotype and also showed reductions in heart rate, which could be partially rescued by dietary copper supplementation. Heart-specific Ctr1A knockdown flies were subsequently examined for heart rate defects using optical coherence tomography (OCT) and while they did have reduced heart rate measurements, heart contractility was compromised. While investigating tissue-specific requirements for Ctr1A in the development of Drosophila, a genetic interaction between Ctr1A and Ras was observed. Genetic experiments in Drosophila and cell culture experiments in both Drosophila and mammalian cell lines demonstrate a conserved role for Ctr1 proteins and copper as positive modulators of Ras/MAPK pathway signaling. Immunoblot analysis shows that signal transduction is intact until the point at which MEK1/2 phosphorylates ERK1/2. MEK2 protein levels are reduced in copper deficient cells, while MEK1 is able to bind copper-chelated beads, suggesting that these two proteins may be copper-binding proteins. In summary, this work demonstrates that Ctr1A is an essential gene in Drosophila and through characterization studies of Ctr1A, has uncovered conserved roles for Ctr1 proteins and copper in physiological processes and in an important signaling pathway that controls a number of fundamental biological processes.</p> / Dissertation