Foram construídas duas montagens experimentais: Com a primeira, mediu-se o decaimento do potencial de superfície em circuito aberto, em função da temperatura; com a segunda mediu-se diretamente a corrente termo-estimulada (derivada do potencial de superfície em circuito aberto) aquecendo-se a amostra a uma taxa constante. Usando essas técnicas estudamos as propriedades de transporte e armazenamento de cargas no Teflon FEP-A, carregado com corona. Usando a segunda técnica, verificou-se que amostras descarregadas, do citado material, podem liberar portadores de cargas positivas que dão origem a uma corrente anômala, que pode interferir nas medidas de corrente termo-estimulada de amostras carregadas positivamente. Estudou-se o comportamento das curvas de corrente em amostras com e sem tratamento térmico, carregadas com corona tanto positiva como negativa. Além disto, é feita uma discussão dos resultados por nós obtidos e os publicados na literatura. / Two experimental systems were constructed: with the first the surface potential could be measured, while with the second, its derivative with respect to the time (the so called open circuit current). In both cases the measurements were performed while heating previously positive or negative corona charged FEP-A Teflon 25&#956m samples. The results gave information about charge storage and transport properties in this material. During the work it was noticed that positive ions maybe emitted from Teflon surface. This unexpected phenomenon was followed in some detail in order to know how far it influences the usual currents. This study led us to carry measurements in previously annealed samples, whose behavior was found to differ from that of virgin samples. Our results were compared with those found in the literature.

Evolution of sex determining mechanisms in squamate reptiles (Reptilia: Squamata) Martina Pokorná Ph.D. thesis Abstract This Ph.D. thesis is focused on the evolution of sex determining mechanisms and genomes in squamate reptiles. It is based on three published articles and two manuscripts. The evolution of sex determining mechanisms, sex chromosomes and genomes, and their organisation, was studied on a wide phylogenetic scale of the whole group of squamate reptiles and some lineages of other Sauropsids, as well as on the small phylogenetic range as a detailed comparative study inside individual lineages of squamates. This thesis is based upon the use of classical cytogenetic methods, methods of molecular cytogenetic (especially fluorescent in situ hybridisation) and the results were analysed using phylogenetic approaches. The results and outputs of this study represent an important contribution to the general knowledge of the principals of sex determination and the evolution of these phenomena not only in squamate reptiles but also in the whole group of amniotes. Using the results obtained during the work on this thesis we can conclude that sex chromosomes evolved in particular lineages of amniotes independently. This origin was in some cases followed by accumulation of microsatellite sequences on sex...

Um método de correção viscosa é aplicado na solução da equação potencial transônica de pequenas perturbações (TSD) no domínio da frequência. O objetivo é melhorar os resultados transônicos em que a interação choque/camada-limite é importante. A espessura de deslocamento da camada limite é estimada, a partir dos resultados da análise do escoamento invíscido, usando um método integral. A espessura de deslocamento é usada, então, para modificar a geometria das superfícies de sustentação e um novo resultado invíscido é obtido. Esse processo é repetido até que se atinja a convergência. No passado esse método foi aplicado, com bons resultados, na análise no domínio do tempo. No domínio da frequência os termos espaciais não lineares são preservados usando uma técnica de transformação conhecida como média harmônica. A principal razão para usar equação TSD ainda é o custo computacional, especialmente em se tratando de configurações completas de aeronaves. Um código de computador original é desenvolvido para análise bidimensional e um código de computador tridimensional existente é modificado para incluir a correção viscosa. A equação TSD é aproximada usando o método das diferenças finitas e resolvida usando sobre-relaxação sucessiva por linhas. Nos dois códigos é utilizada correção para vorticidade e variação de entropia. Os resultados têm boa correlação com dados experimentais publicados para a distribuição de pressão em regime transônico estacionário. / A viscous correction method is applied to the solution of the transonic small disturbance (TSD) potential equation in the frequency domain. The objective is to improve transonic results for which shock/boundary-layer interaction is important. Boundary-layer displacement thickness is calculated, with an integral method, using the results from an inviscid flow analysis. The calculated displacement thickness is then used to modify the lifting surface geometry and a new inviscid result is obtained. This process is repeated until convergence is achieved. In the past that method has been applied to time domain analysis with good results. In frequency domain the spatial nonlinear terms are preserved using a transformation technique known as harmonic averaging. The main reason for using the TSD equation still is computational cost, especially when dealing with complete aircraft configurations. An original computer code is developed for two-dimensional analysis and an existing three-dimensional computer code is extended to include the viscous correction. The transonic small disturbance potential equation is approximated using the finite difference method and solved through successive line over-relaxation. Both codes include correction for vorticity and variation in entropy. Results for several airfoil sections are obtained. The results compare well with published experimental data for steady transonic pressure distribution.

Um método de correção viscosa é aplicado na solução da equação potencial transônica de pequenas perturbações (TSD) no domínio da frequência. O objetivo é melhorar os resultados transônicos em que a interação choque/camada-limite é importante. A espessura de deslocamento da camada limite é estimada, a partir dos resultados da análise do escoamento invíscido, usando um método integral. A espessura de deslocamento é usada, então, para modificar a geometria das superfícies de sustentação e um novo resultado invíscido é obtido. Esse processo é repetido até que se atinja a convergência. No passado esse método foi aplicado, com bons resultados, na análise no domínio do tempo. No domínio da frequência os termos espaciais não lineares são preservados usando uma técnica de transformação conhecida como média harmônica. A principal razão para usar equação TSD ainda é o custo computacional, especialmente em se tratando de configurações completas de aeronaves. Um código de computador original é desenvolvido para análise bidimensional e um código de computador tridimensional existente é modificado para incluir a correção viscosa. A equação TSD é aproximada usando o método das diferenças finitas e resolvida usando sobre-relaxação sucessiva por linhas. Nos dois códigos é utilizada correção para vorticidade e variação de entropia. Os resultados têm boa correlação com dados experimentais publicados para a distribuição de pressão em regime transônico estacionário. / A viscous correction method is applied to the solution of the transonic small disturbance (TSD) potential equation in the frequency domain. The objective is to improve transonic results for which shock/boundary-layer interaction is important. Boundary-layer displacement thickness is calculated, with an integral method, using the results from an inviscid flow analysis. The calculated displacement thickness is then used to modify the lifting surface geometry and a new inviscid result is obtained. This process is repeated until convergence is achieved. In the past that method has been applied to time domain analysis with good results. In frequency domain the spatial nonlinear terms are preserved using a transformation technique known as harmonic averaging. The main reason for using the TSD equation still is computational cost, especially when dealing with complete aircraft configurations. An original computer code is developed for two-dimensional analysis and an existing three-dimensional computer code is extended to include the viscous correction. The transonic small disturbance potential equation is approximated using the finite difference method and solved through successive line over-relaxation. Both codes include correction for vorticity and variation in entropy. Results for several airfoil sections are obtained. The results compare well with published experimental data for steady transonic pressure distribution.

The importance of sex hormones in formation, development and regulation of sexually dimorphic behavior does not need to be stressed. However, their actual organizational and activational effects and interactions in sexual differentiation and determination are not fully understood yet. The aim of our study was to explore the effects of hormonal manipulation in eyelid-geckos (family Eublepharidae) and enlighten the role of steroid hormones in formation of sexual differences. In the first part of our work we tried to reverse sex of Yucatán banded gecko (Coleonyx elegans) by hormonal manipulation in the early embryogenesis. This species has genotypic sex determination with chromosome set X1X2Y. In reverted individuals we aimed to examine the effects of steroid hormones on sexually dimorphic traits and in case of full sexual reversion and fertility of progeny, we would search for the sex-determining gene. In the second part, we studied masculinization effects of testosterone in females of leopard gecko (Eublepharis macularius). In contrast with the Coleonyx elegans mentioned above, this species has temperature dependent sex determination, even though these two species are closely related. Experimental females were implanted with testosterone implants and therefore their testosterone levels were increased in...

Submitted by Nathalya Silva (nathyjf033@gmail.com) on 2017-05-22T19:58:24Z No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Dissertacao_ModelagemEtnomatematicaSituacao.pdf: 1205331 bytes, checksum: 3766cb85fe8651205be975bd08013d65 (MD5) / Approved for entry into archive by Edisangela Bastos (edisangela@ufpa.br) on 2017-05-31T13:01:35Z (GMT) No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Dissertacao_ModelagemEtnomatematicaSituacao.pdf: 1205331 bytes, checksum: 3766cb85fe8651205be975bd08013d65 (MD5) / Made available in DSpace on 2017-05-31T13:01:35Z (GMT). No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Dissertacao_ModelagemEtnomatematicaSituacao.pdf: 1205331 bytes, checksum: 3766cb85fe8651205be975bd08013d65 (MD5) Previous issue date: 2013-08-14 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / A Educação Matemática se preocupa em solucionar os diversos problemas relativos ao ensino e aprendizagem da Matemática. Dentre estes problemas, há em específico, a dificuldade de os discentes e docentes não conseguirem articular o conhecimento matemático escolar às diversas situações impostas pela realidade, principalmente àquelas pertencentes ao seu mundo cultural. O objetivo deste texto científico foi de estudar as práticas cotidianas de um grupo cultural e, a partir dos pressupostos da Modelagem Matemática com abordagem da Etnomatemática, mostrar que ambas podem ser caracterizadas como uma situação a-didática de acordo com a perspectiva da Teoria das Situações Didáticas (TSD). Por não termos envolvido de forma direta alunos nessa pesquisa, buscamos, a priori, estudar algumas obras que indicam o entrelaçamento da Modelagem com a Etnomatemática e, também, criar uma atividade envolvendo os saberes dos mestres-artesãos, responsáveis pela construção de embarcações, utilizando o nosso conhecimento tácito a ser analisada. A intenção foi de verificar os caminhos percorridos durante o processo de Modelagem e compará-los às fases presentes na TSD. O resultado obtido nos permitiu entender que os temas de cunho cultural podem ser usados como ambiente motivador no processo de aprendizagem por fazer parte da realidade dos alunos dessa região, Além disso, indicamos o emprego da Modelagem com o aporte da Etnomatemática pode ser caracterizada como uma situação a-didática por não tentar modificar o conjunto de conhecimentos matemáticos do outro, aqui incluindo os seus argumentos e suas referências culturais, ao impor o que o aluno deva aprender. / Mathematics education is concerned with solving the various problems relating to the teaching and learning of mathematics. Among these problems, there is in particular the difficulty of the students and teachers can not articulate the school mathematical knowledge to various situations imposed by reality, especially those belonging to their cultural world. The aim of this paper was to study scientific everyday practices of a cultural group, and from the assumptions of mathematical modeling approach with the Ethnomatematics, show that both can be characterized as a situation a-didactic according to the perspective of the Theory of Didactic Situations (TSD). By not directly involved students in this research, we a priori study some works that indicate interlacing Modeling to Ethnomatematics and also create an activity involving the knowledge of master craftsmen, responsible for the construction of vessels, using our tacit knowledge to be analyzed. The intention was to check the paths taken through the process of modeling and comparing them to the phases present in the TSD. The results obtained allowed us to understand that the themes of cultural imprint can be used as a motivating environment in the learning process to be part of the reality of the students of this region, also indicated the use of modeling with the input of Ethnomatematics can be characterized as a situation a-didactic not attempt to modify the set of mathematical knowledge of the other, here including their arguments and cultural references, to enforce what the student should learn.

Posttraumatic stress disorder (PTSD) is an anxiety disorder that may result from an exposure to a severely traumatic life-event. It is characterised by a delayed onset of psychological and physical symptoms including re-experiencing the event, avoidance of reminders associated with the trauma, increased autonomic arousal and distinct memory deficits. This disorder is also characterised by a maladaptive hypothalamic-pituitary-adrenal (HPA)-axis response and altered monoamine concentrations in the hippocampus and pre-frontal cortex. The Time Dependent Sensitization (TDS) model is a putative animal model of PTSD that is based on the concept of repeated trauma, using three acute stressors (TS) of intense severity followed by a mild situational reminder (RS) on day 7 subsequent to the acute stressors. The aims of this study were to determine if the Triple Stressor (TS) induces stress and if the situational reminder (RS) is necessary for the maintenance of the stress response over time and whether these two stress responses are qualitatively and quantitively different. This was done to further validate the TDS model and to characterize the development and progression of the stress-related pathology of PTSD. Methods used were High Performance Liquid Chromatography (HPLC) with electrochemical detection (biochemical correlates) for quantifying the monoamines dopamine (DA), noradrenaline (NA) and serotonin (5-HT) concentrations in the hippocampus and pre-frontal cortex (PFC); radio immuno assay (RIA) for the determination of plasma corticosterone concentrations (neuroendocrine parameter) and the use of the Elevated Plus Maze (EPM) to detect anxiety-like behaviour (behavioural analyses). The study was subdivided into an Acute and Re-Stress study (n = 10). In the Acute Study rats were exposed to TS as the only stressor. Group 1 was sacrificed immediately after TS, Group 2 was sacrificed 3 days post TS and Group 3 on day 7 post TS. In the Re-Stress Study both TS and RS were used as stressors. Group 4 was sacrificed immediately after the situational reminder, Group 5 was sacrificed 3 days post RS and Group 6 on day 7 post RS. A group of unstressed rats were used as Control. The results of this study found corticosterone concentrations elevated immediately after the TS (p<0.05). Exposure to the RS resulted in a profound hypocortisolism (p<0.05). These results indicate a possible disturbance in the regulation of the HPA-axis, which manifests as an enhanced negative feed-back upon re-introduction of the stressful situation. Changes in MA concentrations were evident. Although no definite fixed trend is apparent in this study, it is evident that the TDS model does induce monoamine dysregulation. Hippocampal NA. DA and 5-HT concentrations were noted to be elevated on day 7 post TS (p<0.05). On day 7 post RS only hippocampal 5HT was decreased significantly (p<0.05). Behavioural analyses indicate that stress related anxiety was not sustained after the TS but 7 days after the exposure to the RS rats were most anxious (p<0.05). The results confirm that the TDS model does induce PTSD-like symptoms in rats and that the situational reminder (RS) is necessary for the maintenance of the stress response. This model may be useful in the investigation of future experimental pharmacological interventions in the management of PTSD. / Thesis (M.Sc. (Pharmacology))--North-West University, Potchefstroom Campus, 2005.

Posttraumatic stress disorder (PTSD) is an anxiety disorder that may result from an exposure to a severely traumatic life-event. It is characterised by a delayed onset of psychological and physical symptoms including re-experiencing the event, avoidance of reminders associated with the trauma, increased autonomic arousal and distinct memory deficits. This disorder is also characterised by a maladaptive hypothalamic-pituitary-adrenal (HPA)-axis response and altered monoamine concentrations in the hippocampus and pre-frontal cortex. The Time Dependent Sensitization (TDS) model is a putative animal model of PTSD that is based on the concept of repeated trauma, using three acute stressors (TS) of intense severity followed by a mild situational reminder (RS) on day 7 subsequent to the acute stressors. The aims of this study were to determine if the Triple Stressor (TS) induces stress and if the situational reminder (RS) is necessary for the maintenance of the stress response over time and whether these two stress responses are qualitatively and quantitively different. This was done to further validate the TDS model and to characterize the development and progression of the stress-related pathology of PTSD. Methods used were High Performance Liquid Chromatography (HPLC) with electrochemical detection (biochemical correlates) for quantifying the monoamines dopamine (DA), noradrenaline (NA) and serotonin (5-HT) concentrations in the hippocampus and pre-frontal cortex (PFC); radio immuno assay (RIA) for the determination of plasma corticosterone concentrations (neuroendocrine parameter) and the use of the Elevated Plus Maze (EPM) to detect anxiety-like behaviour (behavioural analyses). The study was subdivided into an Acute and Re-Stress study (n = 10). In the Acute Study rats were exposed to TS as the only stressor. Group 1 was sacrificed immediately after TS, Group 2 was sacrificed 3 days post TS and Group 3 on day 7 post TS. In the Re-Stress Study both TS and RS were used as stressors. Group 4 was sacrificed immediately after the situational reminder, Group 5 was sacrificed 3 days post RS and Group 6 on day 7 post RS. A group of unstressed rats were used as Control. The results of this study found corticosterone concentrations elevated immediately after the TS (p<0.05). Exposure to the RS resulted in a profound hypocortisolism (p<0.05). These results indicate a possible disturbance in the regulation of the HPA-axis, which manifests as an enhanced negative feed-back upon re-introduction of the stressful situation. Changes in MA concentrations were evident. Although no definite fixed trend is apparent in this study, it is evident that the TDS model does induce monoamine dysregulation. Hippocampal NA. DA and 5-HT concentrations were noted to be elevated on day 7 post TS (p<0.05). On day 7 post RS only hippocampal 5HT was decreased significantly (p<0.05). Behavioural analyses indicate that stress related anxiety was not sustained after the TS but 7 days after the exposure to the RS rats were most anxious (p<0.05). The results confirm that the TDS model does induce PTSD-like symptoms in rats and that the situational reminder (RS) is necessary for the maintenance of the stress response. This model may be useful in the investigation of future experimental pharmacological interventions in the management of PTSD. / Thesis (M.Sc. (Pharmacology))--North-West University, Potchefstroom Campus, 2005.

Submitted by Rita Cinéia Silva (ritacineia@hotmail.com) on 2017-06-19T17:08:05Z No. of bitstreams: 1 Dissertacao-Rita Cineia-Versão Final.pdf: 4949050 bytes, checksum: a09810a332049e6ed17e88e938d8d36f (MD5) / Approved for entry into archive by Vanessa Reis (vanessa.jamile@ufba.br) on 2017-06-29T11:31:56Z (GMT) No. of bitstreams: 1 Dissertacao-Rita Cineia-Versão Final.pdf: 4949050 bytes, checksum: a09810a332049e6ed17e88e938d8d36f (MD5) / Made available in DSpace on 2017-06-29T11:31:57Z (GMT). No. of bitstreams: 1 Dissertacao-Rita Cineia-Versão Final.pdf: 4949050 bytes, checksum: a09810a332049e6ed17e88e938d8d36f (MD5) / Esta pesquisa tem como objetivo analisar os resultados da integração de Construtos Didáticos à prática dos professores no trabalho com as Operações Aritméticas Básicas. O aporte teórico aqui utilizado se alicerçará em alguns elementos da Teorias das Situações Didáticas, desenvolvida por Guy Brousseau, da Teoria da Instrumentação de Pierre Rabardel e da Teoria do Antropológico do Didático, elaborada por Yves Chevallard. Neste contexto, criamos o termo Malamática para fazer alusão a uma mala que transportará elementos capazes de auxiliar a construção dos Percursos de Estudo e Pesquisa (PEP), no intuito de contribuir com a prática de professores de Matemática. Como questão de investigação, apresentamos: “Como institucionalizar as contribuições de Construtos Didáticos – uma vez que, a incompletude opera na instituição escolar – a partir do trabalho dos professores, no 6° ano, quando ensinam as Operações Aritméticas Fundamentais?”. A pesquisa é de caráter qualitativo, em concordância com John Creswell, e apresenta como campo de investigação três escolas da rede estadual de Feira de Santana-BA. Como aporte metodológico, utilizaremos alguns elementos da Engenharia Didática do PEP, de Yves Chevallard e construiremos um PEP para as quatro Operações Aritméticas Fundamentais. Para produzir os dados, realizaremos visitas às três escolas, entrevistas semiestruturadas com três professores, filmagens e/ou gravação de áudio de algumas aulas, observações naturalistas, como também o uso de questionários abertos para professores e estudantes. Além disso, observaremos anotações nos cadernos dos estudantes, faremos seis encontros para estudos e, em seguida, convidaremos os professores para criarem conosco situações didáticas que integrem as contribuições da Didática da Matemática às Operações Aritméticas Básicas, a partir do que denominamos de Construtos Didáticos. Logo após, solicitaremos que os professores façam a aplicação dos Construtos elaborados envolvendo as quatro operações. Diante do exposto, esperamos que este trabalho possa contribuir com as propostas de ensino da matemática, e, desejamos também, suscitar outras pesquisas com o propósito referido. Ressaltamos ainda que dentre as análises construídas nesta investigação, percebemos que os livros apreciados e a prática pedagógica do professor apresentaram uma preponderância do Modelo Clássico, desenvolvido por Joseph Gascón – modelo que apresenta tendência a um perfil oriundo da interseção dos modelos tecnicista e teoricista. / The aim of this research is to analyze the results of the Didactics devices integration in the practice of teachers in the study of Basic Arithmetic Operations. Our theoretical contribution is based on some elements of the Theories of Didactic Situations developed by Guy Brousseau, the Theory of Instrumentations of Pierre Rabardel and the Antropological Theory of Didactic created by Yves Chevallard. In this context, we created the term (Malamática), mala the word in Portuguese for “suitcase”, to refer to a suitcase that will carry elements capable of assisting the construction of Study and Research Paths (PEP in Portuguese), aiming to contribute to the practice of mathematics teachers. As a research question, we present: "How to institutionalize the contributions of Didactic Constructs - since incompleteness operates in the school institution - from the work of the teachers, in the 6th year, when they teach the Fundamental Arithmetic Operations?". The research is of a qualitative nature, in agreement with John Creswell and it presents as a research field three schools of the network of Feira de Santana-BA. As a methodological contribution, we will use some elements of the PEP Didactic Engineering, by Yves Chevallard and construct a PEP for the four Fundamental Arithmetic Operations. To produce the data, we will visit three schools, semi-structured interviews with three teachers, filming and / or audio recording of some classes, naturalistic observations, as well as the use of open questionnaires for teachers and students. In addition, we will observe notes in the students' notebooks, we will make six study meetings and then invite teachers to create with us didactic situations that integrate the contributions of Didactics of Mathematics to Basic Arithmetic Operations, from what we call Didactic Constructs. Right after, we will ask that the teachers make the application of the elaborated constructs involving the four operations. Based on the considerations above, we hope that this work can contribute to the mathematics teaching proposals, and we also wish to raise other research for the purpose We also emphasize that among the analyzes constructed in this research, we noticed that the books appreciated and the pedagogical practice of the teacher presented a preponderance of the Classical Model, developed by Joseph Gascón - a model that shows a tendency from the intersection of technical and theoretical models.

L’adoption par l’OMC de mesures de TSD utiles pour promouvoir l’agriculture des PED par le commerce agricole a favorisé l’accès des PED au marché rémunérateur de l’UE par des schémas multiples qui ne sont pas encore répartis équitablement entre les PED. Les préférences tarifaires de l’UE accordées aux PED figurent parmi les plus importants instruments de développement commercial utilisés par les pays développés. Cependant, l’effectivité des mesures de TSD reste relative à cause des limites inhérentes à leur contenu influencé par le statut particulier de l’agriculture à l’OMC. L’UE continue de bénéficier d’arrangements spéciaux et pratique un protectionnisme agricole très complexe et très décrié sur le plan externe. Les politiques commerciales, agricoles, sociales, environnementales et sécuritaires en vigueur dans le marché agricole européen neutralisent les efforts consentis par les PED, plus particulièrement les PMA et les pays ACP, pour exploiter les préférences. L’avenir de l’accès des PED au marché agricole de l’UE est actuellement lié à l’aboutissement incertain des négociations du Cycle Doha sur le TSD et l’agriculture. Les Conférences ministérielles de Bali (décembre 2013) et de Nairobi (décembre 2015) ont permis de mettre sur pied des accords partiels et a minima qui semblent maintenir le déséquilibre subtil entre un TSD peu contraignant et un statut particulier de l’agriculture toujours résistant à l’OMC, sans apporter une solution définitive au statu quo de l’accès des PED aux marchés agricoles des pays développés. Les enjeux et les perspectives de l’accès des PED au marché agricole de l’UE dépendent de la direction que prendront les travaux en cours pour répondre aux questions de développement et de libéralisation agricole dans le cadre d’un vrai cycle de développement. / The adoption by the WTO of special and differential treatment (SDT) measures that are useful for promoting the agriculture of developing countries through agricultural trade has favored the access of developing countries to the remunerative market of the EU through multiple schemes that are not yet evenly distributed between developing countries. EU tariff preferences for developing countries (DCs) are among the most important trade development instruments used by developed countries. However, the effectiveness of SDT measures remains relative because of the limitations inherent in their content influenced by the special status of agriculture in the WTO. The EU continues to benefit from special arrangements and practices agricultural protectionism that is very complex and highly criticized externally. The commercial, agricultural, social, environmental and security policies in force in the European agricultural market neutralize the efforts made by developing countries, in particular least developed countries (LDCs) and ACP countries, to exploit preferences.The future access of developing countries to the agricultural market of the EU is currently linked to the uncertain outcome of the Doha Round negotiations on SDT and agriculture. The Ministerial Conferences in Bali (December 2013) and Nairobi (December 2015) have led to the establishment of partial and minimum agreements that seem to maintain the subtle imbalance between a non-constraining SDT and a particular status of agriculture that is still resistant to The WTO without providing a definitive solution to the status quo of DCs access to agricultural markets in developed countries. The challenges and prospects of developing countries' access to the EU agricultural market depend on the direction of work in progress to address agricultural development and liberalization issues within a real development cycle.