L'expression intracellulaire des anticorps (intracorps) est une approche qui permet l'étude et le ciblage des antigènes dans les compartiments intracellulaires. Néanmoins, l'expression d'anticorps entiers fonctionnels dans les cellules reste une tâche difficile en raison de leur grande taille et de leur structure, l'environnement réducteur du milieu intracellulaire étant défavorable à la formation des ponts disulfure. Notre groupe a une forte expertise dans le domaine de l'immunisation intracellulaire et son application pour l'identification de nouvelles cibles thérapeutiques. Pour cela, notre équipe a élaboré des banques de fragments d'anticorps scFv optimisés pour une meilleure expression intracellulaire. Nos travaux antérieurs ont démontré que ces intracorps peuvent cibler spécifiquement des domaines ou des modifications post-traductionnelles de protéines dans des cellules vivantes. Ceci est particulièrement important car il démontre l'un des avantages principaux des intracorps par rapport à l'approche basée sur l'ARNi. Cet avantage a été démontré par un criblage phénotypique dans un modèle d'allergie. En appliquant cette approche à l'étude de l'activation des mastocytes, nous avons pu identifier un nouvel acteur moléculaire impliqué dans la voie de signalisation mise en jeu. Ce travail a été protégé par un brevet européen en 2013 et est publié récemment. Dans le cadre de mon projet de thèse, j'ai construit une nouvelle banque synthétique (HUSCIv) optimisée pour la stabilité, la diversité et l'affinité des scFvs. Pour cela, le scFv 13R4 isolé dans notre équipe a servi de charpente pour le greffage des différentes boucles hypervariables, tout en respectant la diversité des régions CDR observée dans les anticorps naturels humains. Nous avons utilisé la protéine GFP en tant que rapporteur pour étudier le repliement et la solubilité des intracorps. Nos résultats ont clairement démontré que la plupart des intracorps issus de la banque HUSCIv sont soluble dans le cytoplasme des cellules mammifères. Mon projet de thèse décrit ici rapporte l'utilisation de la banque HUSCIv pour un criblage phénotypique dans des cellules de cancer colorectal portant une mutation du gène K-RAS et résistantes au traitement par l'anticorps chimérique Cetuximab. Le projet cherche à sélectionner des scFv capables de restaurer la sensibilité au Cetuximab, avec comme objectif l'identification des cibles intracellulaires impliquées.Pour ce criblage fonctionnel, la banque HUSCIv a été exprimée dans les cellules HCT116 par l'intermédiaire d'un système d'expression rétroviral. Le processus de sélection est basé sur la sélection directe de la prolifération des cellules en utilisant un colorant fluorescent (CMRA). Les cellules dont la prolifération est bloquée sont isolées et un séquençage à haut débit permet de suivre l'évolution des populations de scFv tout au long de l'expérience. Ainsi, ce projet a nécessité un séquençage profond d'un grand nombre de scFv afin de réaliser une analyse statistique. Nous avons réalisé à ce jour deux tours de sélection. Les tests de cytotoxicité réalisés sur les populations sélectionnées ont montré une inhibition significative de la prolifération en présence du Cetuximab d'environ 10%. Ces résultats indiquent l'évolution du phénotype qui tend vers une sélection de scFv inhibiteurs et suggèrent que nous devons réaliser au moins un ou plusieurs tours plus sélectifs avant de formuler des conclusions.L'approche introduite ici est différente de toutes les études existantes en ce qu'elle utilise des banques « naïves », et permet non seulement de répondre à la diversité du protéome, mais aussi d'étudier les messagers secondaires et le métabolisme des cellules. En tant que tel, et par rapport à d'autres approches à grande échelle, celle-ci représente une voie simple pour la découverte de molécules thérapeutiques potentielles. / Intracellular expression of antibodies (intrabodies) permitted the study and targeting of antigens in cellular compartments. However, the expression of functional intrabodies remains a difficult task due to their large size, structure, and the reducing intracellular environment. Our group has a strong expertise in the field of intracellular immunization and the identification of new therapeutic targets. For this purpose, we have developed an scFv library optimized for intracellular expression of scFv antibody fragments. Our previous works have shown the successful use of intrabodies for targeting specific domains or post-translational modifications in living cells. This is particularly important because it demonstrates one of the main advantages of intrabodies compared to the approaches using RNAi. This benefit was demonstrated by a phenotypic screen in a model of allergy. Applying this approach to the study of mast cell activation, we identified a new molecular player involved in the signaling pathway implemented. This work was protected by a European patent in 2013 and was recently published. As part of my thesis project, I designed a new synthetic library (HUSCIv) optimized for scFv stability, diversity and affinity. For this, a highly soluble and hyper-stable framework, scFv13R4 isolated in our group, was used as a scaffold for grafting different hypervariable loops, while respecting the diversity of CDRs observed in human natural antibodies. We used protein GFP as a reporter to study the folding and solubility of intrabodies. Our findings clearly demonstrated that most of the intrabodies from HUSCIv library are soluble in the cytoplasm of mammalian cells. My thesis project described here reports the use of HUSCIv in a phenotypic screen of colorectal cancer cells carrying a mutation in the K-RAS gene and resistant to the treatment with the chimeric antibody Cetuximab. The project seeks to select scFv fragments able to restore the sensitivity to Cetuximab, with the objective to identify the intracellular targets involved. For this functional screen, the HUSCIv library was expressed in HCT116 cells via a retroviral expression system. The selection process is based on the direct selection of cell proliferation using a fluorescent dye (CMRA). The cells whose proliferation is blocked are isolated and the evolution of scFv populations throughout the experiment are tracked via high-throughput sequencing. This sequencing requires a large number of scFvs to perform a statistical analysis. So far, we have achieved two rounds of selection. The cytotoxicity tests carried out on the selected populations showed a significant inhibition of proliferation (10%) in the presence of Cetuximab. These results indicate that the evolving phenotypes are tending towards a selection of scFv inhibitors and suggest that we need to perform at least one or more selective rounds before making conclusions. The approach introduced here is different from all existing studies in that it uses "naive" libraries not only to respond to the diversity of the proteome, but also to study secondary messengers and metabolism in cells. As such, and in comparison to other large-scale approaches, it is a simple way for the discovery of potential therapeutic molecules.

Les particules fines ont un impact réel sur la qualité de vie et la santé de millions de personnes dans les grandes zones urbaines, notamment en Asie. Pour les détecter et quantifier leur concentration, les capteurs de particules optiques sont les plus couramment étudiés, mais restent relativement chers et volumineux. Les transducteurs MEMS micropoutres sont largement utilisés pour des applications gravimétriques, pour la détection de particules ou de gaz, ce qui requiert des sensibilités massiques (Sm) élevées et des limites de détection (LOD) basses. Pour cela les micropoutres les plus adaptées sont celles ayant des fréquences de résonance (f0) et facteurs de qualité (Q) élevés, avec de faibles bruits de mesure et des masses faibles. Les micropoutres silicium sont couramment utilisées en tant que capteurs gravimétriques et sont de sérieux candidats pour répondre aux caractéristiques souhaitées. Cependant, la sérigraphie a le potentiel pour une fabrication moins chère, plus rapide et aussi à grande échelle. Pour ces micropoutres, l'actionnement et la lecture de f0 sont possibles par effet piézoélectrique. Bien qu'il existe des solutions inorganiques prometteuses sans plomb, les céramiques de titano-zirconate de plomb (PZT) possèdent encore les meilleures propriétés parmi les matériaux piézoélectriques. Des micropoutres fabriquées en technologie hybride couches épaisses sérigraphiées, à actionnement et lecture piézoélectriques intégrés, libérées à l'aide d'une couche sacrificielle polyester et avec co-cuisson de toutes les couches pour leurs libérations sont présentées ici. Différentes géométries ont été testées de 1 mm à 2 mm de large et de 1 mm à 8 mm de long, pour une épaisseur d'environ 100 μm. Une masse volumique ρ PZT = 7200 kg/m³ a été obtenue (≈ 93%ρ PZT massif). Enfin, avec une micropoutre 1×2×0,1 mm³, une sensibilité Sm ≈ 85 Hz/μm et une LOD de 70 ng ont été trouvées, permettant des applications en détection de particules. / Fine particulate matters (PM) have a real impact on the quality of life and health of millions of people in large urban areas, especially in Asia. In order to detect them and quantify their concentration, optical PM sensors are the most widely studied, but remain relatively expensive and bulky. MEMS microcantilever transducers are widely used for gravimetric applications, for PM or gas detection, which requires high mass sensitivities (Sm) and low limits of detection (LOD). A solution is to focus on microcantilevers with high resonance frequencies (f0) and quality factors (Q), low measurement noise and low masses. Silicon microcantilevers are commonly used as gravimetric sensors and are serious candidates to meet the desired characteristics. However, screen printing has the potential for cheaper, faster and large scale manufacturing. Such microcantilevers can be actuated and f0 read-out using the piezoelectric effect. Although promising lead-free inorganic solutions exist, titanium lead zirconate (PZT) ceramics still have the best properties among piezoelectric materials. Screen-printed microcantilevers manufactured in hybrid thick-film technology, with integrated piezoelectric actuation and read-out, released using a polyester sacrificial layer and with co-firing of all the layers are presented here. Different geometries were tested from 1 mm to 2 mm wide and from 1 mm to 8 mm long, for a thickness of about 100 μm. A density ρ PZT = 7200 kg/m³ (≈ 93%ρ PZT bulk) was obtained. With a 1×2×0.1 mm³ microcantilever, a sensitivity Sm ≈ 85 Hz/μm and a LOD of 70 ng were found, compatible with applications in PM mass detection.

Vi upplever att vi jämt är omgivna av digitala apparater och av digitalisering. Kandidatarbetets tema är ett vågat ämne där vi undersöker hur mobiltelefonen påverkar vårt psykiska välmående och vilka möjliga lösningar det finns på hur problemen kan hanteras. Vi skriver om vad det finns för mobilapplikationer som kan terapeutiskt hjälpa användaren att utveckla och förbättra sitt välmående. Från våra kunskapsområden vill vi med vår mobilapplikation bygga upp välmående. Den ska terapeutiskt hjälpa den som är i behov och som behöver hjälp att må bättre. Vi fördjupar oss i detta ämnesområde där vi ser det från vårt perspektiv med våra ögon och hanterar det efter våra erfarenheter.   Vi tillämpar designperspektivet X for Change som tar upp samhällsfrågor, i detta fall så är det om folkhälsa. X for Change ska inte på något sätt vara upprörande eller provocerande i de frågor som besvaras, utan vara till hjälp under hela kandidatarbetet. Designprocessen delades in i två faser där ändringar av gestaltningen ägde rum. Under denna undersökning går vi in på nya gestaltningsmetoder där vi skapar färdiga prototyper från idé till hi-fi prototyper för vår mobilapplikation. Detta är ett vågat försök där vi testar oss fram och med tiden utvecklat en ny förmåga i vårt skapande som designers. / We believe that we are constantly surrounded by digital devices and by digitalization. The theme of this bachelor’s thesis is a daring subject where we investigate how the mobile phone affects a person's mental wellbeing and what possible solutions there are on how to deal with those problems. We are writing about what kind of mobile applications there are that can help users develop and improve their wellbeing. From our area of expertise, we want with our mobile application help users to improve their mental health and promote wellbeing. It is meant to work as a therapeutic tool to those who are in need of help to feel better. We immerse ourselves in this topic where we see it from our own perspective with our own eyes and manage it based on our own experiences.   We use the design perspective X for Change that brings up certain societal issues, in this case it's about the public health. X for Change is not meant to be upsetting or provoking on the topic of these questions but be of help throughout the whole thesis. The design process is split into two phases, where changes to our application took place. During the whole investigation we enter new methods to create our application where we create finished prototypes from ideas to hi-fi prototypes for our mobile application. It is a bold attempt where we test ourselves and with time we have created a new ability in our creativity as designers.

Sidladdningar på webbplatser har visat sig ha stor påverkan på hur användare beter sig på webbplatser. Redan efter 1 sekunds fördröjning börjar användarens beteende ändras. Laddningsindikatorer kan användas för att minska den upplevda hastigheten av sidladdningar. Det finns olika varianter av laddningsindikatorer som fungerar på olika sätt. En traditionell laddningsindikator är spinner och en nyare, mindre undersökt, heter skeleton screen.  Syftet med denna kandidatuppsats har varit att undersöka effektiviteten hos skeleton screen att påverka den upplevda hastigheten av sidladdningar. Dessutom var syftet att utforma och demonstrera ett test för att förse webbutvecklare med vägledning om hur liknande test kan genomföras i syfte att avgöra vilken laddningsindikator de bör välja att använda vid utveckling. En prototypisk webbsida skapades i två olika versioner, en med 2 sekunders fördröjning och en med 4 sekunders fördröjning vid sidladdning. För att ladda sidorna användes spinner eller skeleton screen. För att samla in användares upplevda hastighet av webbplatsen utfördes användartester där deltagarna för varje sida fick uppskatta hur lång tid nedladdningen tog. Totalt deltog 14 testpersoner i åldrarna 13–47 år. Resultatet visade på att skeleton screen påverkade testpersonernas upplevda hastighet som kortast i både versionerna. Medelvärdet av alla resultatet från testpersonerna visade på att vid 2 sekunders fördröjning upplevdes sidladdningar som 0.89 sekunder med skeleton screen och 1,95 sekunder med spinner. Vid 4 sekunders fördröjning upplevdes skeleton screen som 1,38 sekunder och spinner 3,81 sekunder. Trots att skeleton screen var den laddningsindikator som minskade upplevd hastighet mest, fanns det delade åsikter om vilken laddningsindikator testpersonerna föredrog baserat på design och tidigare erfarenheter. Skeleton screen verkar inte vara meningsfulla på sidor med enstaka produkter, utan effektiviteten av skeleton screen visades främst vid laddning av flera produkter.

The purpose of this research paper was to explain how product placement in games influences the consumer’s attitude towards the brand. The aims during this work with the purpose in mind were to utilize quantitative methods in the pursuit of fulfilling the objective of answering how certain placement strategies can affect individual consumer’s attitudes. As said, quantitative methods are used in combination with deductive reasoning, hence meaning that researchers of this paper make use of such programs like google docs questionnaire (for collecting data and creating surveys), SPSS statistics (for measuring the given data and assembling patterns/relationships). Since these kinds of methods were used, it means that both primary and secondary sources were made use of by the authors. Findings concerning the research put forward in this paper indicates that the most significant kind of placement strategy which is motivated why its significance value, is Plot and narrative placement. research presented in this work is represented by three hypotheses. H1-screen placement, H2 -script placement and H3 plot placement. All hypothesis except the third one was accepted through 2 produced positive results (H2, H3) while one produced negative results (H1). As a wrap-up summary of this, consumers who play games seem to have a more positive attitude towards brands utilizing screen and plot placement rather than script placement. Hence having a better attitude when it comes to product placement in games compared from the previous studies. Researchers suggest using qualitative research to cover for more factors concerning product placement in games which may affect consumers'' attitude toward brands. This together with a further focus on random sampling may produce an interesting result.

A presente dissertação se dedica a mapear a organização do trabalho na atual cadeia produtiva do audiovisual na cidade de São Paulo, por meio da análise das atuais formas de produção do cinema e do atual modelo de financiamento do setor, com o objetivo de evidenciar seus principais elos e suas principais vulnerabilidades. Um setor identificado como vulnerável, porém, pouco evidenciado, está localizado no início da cadeia produtiva o desenvolvimento de projetos. Essa etapa, que inicia todo o processo do filme, está muito centrada na figura de um profissional o roteirista. Portanto, esta pesquisa está centrada na identificação da vulnerabilidade desse profissional, em suas relações de trabalho e seus níveis de relacionamento, em sua influência nos outros setores da cadeia produtiva, como também, na atual condição de trabalho que lhe é ofertada. Foram identificadas três questões centrais para justificar a atual vulnerabilidade da profissão de roteirista, que se desmembram em outros apontamentos, são elas: a disputa de autoria entre diretor e escritor no final dos anos 60 (cinema e literatura), as relações flexíveis impostas pelo novo modelo de trabalho apoiado na lógica da intermitência e fragmentação e por último, a falta de organização do profissional de roteiro enquanto categoria. / This thesis aims at drawing a map of the current state of the audiovisual industry productive chain in the city of São Paulo. I shall analyse the current forms of film production and the sector\'s funding model, seeking to outline its most relevant nodes and its main vulnerabilities. One particular aspect that has been identified as vulnerable, while rarely identified, is located at the beginning of the productive chain: project development. This stage, which upstarts the whole film process, is very centered on one sole professional: the writer. Therefore, this research is oriented at the identification of vulnerabilities pertaining to this professional in particular, in their work relations and levels of relationship, in their influence on other sectors of the production chain, as well as in the current working conditions offered to them. Three main questions have been identified, which explain the current vulnerability of the writer profession. These questions are developed into other remarks. The three questions are namely: the dispute surrounding authorship, between director and writer, at the end of the 1960s (cinema and literature); the flexible relations imposed by the new working model supported by the logic of precariousness and fragmentation; and the lack of professional organizations among writers as a social category.

A obstrução de emissores tem sido um entrave para a microirrigação. Porém, tem-se notado poucos estudos relativos ao desenvolvimento de equipamentos que auxiliam na prevenção da obstrução de emissores nos últimos anos. Os estudos realizados nesta linha estão geralmente ligados à caracterização dos sistemas em uso. O objetivo deste trabalho foi desenvolver um sistema de filtragem com reversão automática de fluxo, de alta frequência. O sistema foi concebido para operar com água de baixa qualidade, com inversão de fluxo e limpezas automáticas e com volume mínimo de água para realização das limpezas. As decisões do controlador do sistema de filtragem têm como base a perda de carga, obtida por meio de transdutores de pressão instalados na entrada e na saída do sistema. O protótipo final é composto, basicamente, por três filtros de tela e onze válvulas solenoides controladas eletronicamente. Determinou-se a curva de perda de carga em função da vazão, a eficiência de retenção e o volume mínimo de água para limpeza dos filtros. A eficiência de retenção de partículas foi determinada em delineamento experimental inteiramente aleatorizado em esquema fatorial, sendo testados três fatores: tempo de reversão (15 e 30 s); incremento da perda de carga (25 e 50%) e concentração de sólidos (500 e 1000 mg L-1). A eficiência de retenção de sólidos totais foi de 71,7 e 78,3% para as concentrações de 500 e 1000 mg L-1, respectivamente, tendo apresentado diferença significativa a 1% de probabilidade. Entretanto, a eficiência retenção de sólidos maiores que 50 ?m (Ed > 50) foi de 98,6 ± 0,7%, não sendo significante para nenhum dos tratamentos ao nível de significância de 1%. O volume médio de água despendido durante as limpezas foi de 5,39 L por limpeza, que representou um volume de água de limpeza por volume de água filtrada de 8,0 e 12,6 L m-3, para as concentrações de 500 e 1000 mg L-1, respectivamente. Os valores de eficiência energética do sistema de filtragem variaram de 80 a 90% para a vazão de 2 m3 h-1 com pressão de entrada entre 15 a 40 mca. As limpezas do sistema de filtragem não foram totalmente eficazes na retomada da perda de carga, com tendência de aumento com o tempo. A inversão de fluxo com frequências de 11,11 e 22,22 mHz influenciou na evolução da perda de carga do sistema de filtragem, tornando-a mais lenta que a evolução para o sistema funcionando sem inversão de fluxo. Considerou-se que o sistema de filtragem desenvolvido apresentou potencial para filtragem da água de irrigação com baixa qualidade, porém necessita de manutenções periódicas para limpeza do elemento filtrante. A perda de carga admissível do sistema de filtragem deve ser o valor mais restritivo entre o critério de desempenho de retenção de partículas e o de variação de vazão do sistema de irrigação. / Emitters clogging have been a barrier to trickle irrigation. Just a few studies have been performed concerning equipments which assist in preventing emitters clogging in recent years, especially regarding to development equipment. Studies carried out on this issue are usually linked to the characterization of systems in use. The aim of this study was to develop a filtering system with automatic flow reversal of high frequency. The system is designed to operate with low quality water, with reverse flow and automatic cleanings and with minimum volume of water to perform the cleaning. Decisions by the controller of the filtration system are based on head loss, obtained by pressure transducers installed at the upstream and downstream of the system. The final prototype consists of three screen filters and eleven electronically controlled solenoid valves. The curve of head loss was determined as a function of water flow, retention efficiency and minimum volume of water required for cleaning the filters. The efficiency in particle retention was determined following a completely randomized experimental design in a factorial scheme in which three factors were tested: reversal time (15 and 30 s) increase in head loss (25 and 50%) and solids concentration (500 and 1000 mg L-1). The total solids retention efficiency was 71.7 and 78.3% for concentrations of 500 and 1000 mg L-1, respectively, presenting a significant difference at 1%. However, when analyzing the retention efficiency of solids larger than 50 ?m (Ed> 50), none of the treatments was significant at 1%, whose efficiency was 98.6 ± 0.7%. The mean volume of water expended during the cleaning was 5.39 L. It represented a volume of water for cleaning per volume of filtered water from 8.0 and 12.6 L m-3, to concentrations of 500 and 1000 mg L-1, respectively. The energy efficiency values of filtering system ranged from 80 to 90% considering flow rate of 2 m3 h-1 and inlet pressure ranging from 15 to 40 mca. The filtering system cleaning was not totally effective in reestablishing the head loss, with an upward trend over time. The reverse flow with frequency of 11.11 and 22.22 mHz influenced the head loss evolution of the filtration system, making it slower than the trend for the system running without flow reversal. The developed filtration system has potential for filtering low quality irrigation water, but it requires periodic maintenance to clean the filter element. The allowable head loss of the filter system should be the most restrictive value between the criterion of particle retention performance and the flow variation of the irrigation system because of the increase in head loss in the filters.

Nonsense mediated mRNA decay (NMD) is a surveillance mechanism that targets transcripts containing premature stop codons (PTCs) for degradation, and that also regulates up to 10% of the whole transcriptome. During the course of my PhD I set out to identify novel NMD factors by performing a genome-wide RNA interference (RNAi) screen in a transgenic strain of Caenorhabditis elegans carrying an NMD reporter. I identified five novel proteins that are putative NMD factors in worms: NGP-1, NPP-20, AEX-6, PBS-2 and NOAH-2. Knock-down of these proteins led to severe developmental defects: worms were either arrested during various larval stages or died prematurely. The only exception was AEX-6, the knockdown of which led to a milder phenotype. Homology analysis of the novel C. elegans NMD factors showed that these proteins are conserved in human, with the exception of NOAH-2, which only has a homologue in Drosophila melanogaster, NOMPA. By performing an NMD assay in human cells, I demonstrated that GNL2 (NGP-1) and SEC13 (NPP-20) are functionally conserved NMD factors in human. Analysis of the consequences of depletion of GNL2, SEC13, UPF1 or UPF2 on the transcriptome of HeLa cells revealed that these four proteins co-regulate a subset of endogenous NMD targets, whilst also independently regulating the expression of other sets of transcripts. The findings presented in this thesis further our knowledge of the biology of NMD in both nematodes and humans. They demonstrate the existence of further regulators of this surveillance pathway, and add a layer of complexity to this fine-tuned biological process.

Na década de60, Andy Warhol começou a trabalhar com as técnicas da serigrafia. Copiava imagens gráficas e fotográficas e as transferia diretamente para a tela. O artista abandonou os modos mais tradicionais de pintura e passou a trabalhar com a apropriação de imagens reproduzidas em série nos cartazes, fotografias, embalagens e no cinema. O uso destes clichês gráficos causou controvérsia. Uma série de discussões tentava entender a escolha do artista a partir de interlocuções dele com a obra de outros criadores e como uma interpretação de fatos da realidade social. A partir destas análises, este trabalho busca construir uma interpretação alternativa que entenda as razões para a modificação de procedimentos e linguagens na obra de Andy Warhol e o seu impacto na produção do século XX. / Andy Warhol started to work with the silkscreen techniques in the 1960s. Graphic and photographic images were copied and transferred straight onto canvas. The artist abandoned the traditional modes of painting and began working with the appropriation of serialized images from billboards, photos, packages and film. The use of such clichés was controversial. In several discussions, critics tried to understand Warhol\'s choices from his dialogue with other artists and as an interpretation of the facts of social reality. This study attempts to build an alternative interpretation that tries to understand the reasons for the modification of procedures and poetics in the Andy Warhol\'s work and his impact on the 20th century art.

"This study characterizes the image quality parameters of a clinical full-field digital mammography system at various x-ray spectral conditions. The energy of the incident x-ray beam, the spectral characteristics, and breast thickness impact the physical performance such as the detective quantum efficiency of the system, thereby affecting the overall performance. The modulation transfer function, noise power spectrum were measured without the anti-scatter grid, and the detective quantum efficiency was calculated for different incident x-ray conditions. Detective quantum efficiency was also calculated with the anti-scatter grid placed above the detector to study its impact. Results indicate a substantial drop in the detective quantum efficiency with the anti-scatter grid under certain conditions. It was also determined that detective quantum efficiency decreases as x-ray beam hardening is increased. A spatial frequency-dependent cascaded liner systems model was developed to predict the detective quantum efficiency of the system for different target-filter combinations. This theoretical model is based upon a serial cascade approach in which the system is conceptually divided into a number of discrete stages. Each stage represents a physical process having intrinsic signal and noise transfer properties. A match between the predicted data and the experimental detective quantum efficiency data confirmed the validity of the model. Contrast-detail performance, a widely used quality control tool to assess clinical imaging systems, for the clinical full-field digital mammography was studied using a commercially available CDMAM phantom to learn the effects of Joint Photographic Experts Group 2000 (JPEG2000) compression technique on detectability. A 4-alternative forced choice experiment was conducted. The images were compressed at three different compression ratios (10:1, 20:1 and 30:1). From the contrast-detail curves generated from the observer data at 50% and 75% threshold levels, it was concluded that uncompressed images exhibit lower (better) contrast-detail characteristics than compressed images but a certain limit to compression, without substantial loss of visual quality, can be used."