Atualmente, a Leucemia Linfocítica Crônica (LLC) pode ser dividida em dois grupos: um com mutações somáticas no gene da região variável da cadeia pesada da imunoglobulina (MIgVH) e outro sem mutações (NMIgVH). Alguns estudos mostraram que a expressão de CD38 na superfície das células B de LLC pode estar correlacionada com o estado mutacional do gene VHIg, entretanto, esses controversos. Estudos recentes mostraram que a expressão da proteína tirosina quinase Zap-70 está melhor associada com o estado mutacional do gene IgVH. O objetivo deste estudo foi avaliar a expressão de Zap-70 e CD38, por citometria de fluxo, nas células CD19+ de pacientes com LLC e correlacioná-los com o estádio clínico (EC), sobrevida livre de tratamento (SLT) e sobrevida global (SG). A expressão de Zap-70 e CD38 foi avaliada, em 144 de pacientes com LLC classificados nos estádios clínicos A, B e C de acordo com os critérios de Binet: 59 (41%) do EC-A, 38 (26%) do EC-B e 47 (33%) do EC-C. Foi observada menor positividade para Zap-70 e CD38 nos pacientes do EC-A do que nos EC-B e C. Quando avaliada a SLT nos pacientes do EC-A, os casos Zap-70+ assim como os CD38+ apresentaram menor SLT. A média de SG dos pacientes Zap-70+ e CD38+ foi menor quando comparado com os Zap-70- e CD38- entretanto quando correlacionada com o EC não foi observada diferença estatisticamente significante entre a expressão desses marcadores e o EC-A, B ou C. Pela analise combinada de CD38 e Zap-70, dividimos os pacientes em dois grupos (Zap-70-/CD38- e Zap-70+ ou CD38+). Observamos que a expressão positiva desses dois marcadores estava associada ao EC, uma vez que a grande maioria dos pacientes dos estádios B (74%) e C (66%) expressam Zap-70 ou CD38. Entretanto, os pacientes do EC-A, Zap-70+ ou CD38+, apresentaram SG menor quando comparado com os Zap-70-/CD38-. Essa diferença não foi observada nos pacientes do EC-B e do EC-C. Também foi observada menor SLT nos pacientes no EC-A, Zap-70+ ou CD38+. Esses resultados sugerem que análise combinada de Zap-70 e CD38 podem ser empregadas na avaliação dos pacientes do EC-A para se acompanhar a evolução clinica desse grupo de pacientes. Porém, estudos adicionais devem ser realizados para se validar a utilização clínica desses marcadores. / Actually, chronic lymphocytic leukemia (CLL) can be divided in two subsets: one with somatically mutated immunoglobulin heavy-chain variable-region genes (MIgVH) and other with unmutated sequences. (UMIgVH). Some studies have shown that CD38 expression in CLL cells are correlated with IgVH mutational status. However, the value of CD38 as surrogate IgVH mutational status is controversial. Recent studies, have found that Zap-70 protein tyrosine kinase expression is strongly associated with the mutational status IgVH. The aim of this study was to evaluate the Zap-70 and CD38 expression, for flow cytometry, in CD19+ LLC cells and correlate with the Binet’s staging system, treatment-free survival (TFS) and a overall survival (OS). Zap-70 and CD38 was evaluated, in 144 CLL patients that was classified in A, B and C Binet’s staging system: 59 (41%) in stage A, 38 (26%) in B and 47 (33%) in C. We observed low Zap-70 and CD38 expression in stage A patients than in stage B and C cases. When we analyzed the TFS in stage A patients Zap-70+ and CD38+ patients showed shorter TFS than Zap-70- and CD38-. Then we observed that the OS of Zap-70+ and CD38+ patients was, also, shorter than Zap-70- and CD38- cases. However, statistical differences was not found when Zap-70 and CD38 expression was correlated with stage A, B or C Binet’s staging system. To understand the associated Zap-70 and CD38 expression, we divided the CLL patients in two subgroups (Zap-70-/CD38 - and Zap-70+ or CD38+). We observed that CD38+ or Zap-70+ was associated Binet’s staging system, once most of stage B (74%) and C (66%) patients are Zap-70+ or CD38+. However, stage A patients, Zap-70+ or CD38+, showed shorter OS than Zap-70-/CD38-. These differences were not observed in stage B and C patients. Shorter TFS was also observed in the Zap-70+ or CD38+ stage A patients. These results suggest that combined analysis of Zap-70 and CD38 can be used to evaluate stage A patients to observe the clinical evolution of the disease. Nevertheless, other studies must be carried to confirm the clinical use of these markers.

No description available.

[pt] O projeto mecânico de componentes estruturais para vidas longas à fadiga requer limites de fadiga confiáveis. Porém, a previsão do limite de fadiga ainda apresenta alguns desafios, especialmente por causa dos inevitáveis entalhes e pela presença de pequenos defeitos intrínsecos do material que podem ser considerados como microtrincas. Os entalhes atuam como concentradores de tensão e microtrincas podem ser geradas na ponta destes. Tais microtrincas (geradas ou intrínsecas) podem propagar até provocar a falha do componente ou parar de propagar depois de crescer uma pequena distância e se tornarem não-propagantes, dependendo do nível de carga e do gradiente de tensão à frente do entalhe. Modelos empíricos e teóricos têm sido propostos para fazer previsão do limite de fadiga de componentes entalhados. Entre os teóricos, o chamado modelo do Gradiente de Tensão (GT), que utiliza conceitos da mecânica da fratura linear elástica, apresenta-se como um modelo promissor. No entanto, a validação experimental das previsões deste modelo ainda não tem sido completamente realizada. Neste contexto, corpos de prova tipo C(T) do aço 1020 e com vários valores do raio da ponta do entalhe foram testados sob controle de amplitude de carga constante, frequência de 40 Hz e razão de tensão R igual a 0.1 para avaliar o limite de fadiga através de testes acelerados com cargas tipo step up durante blocos de 3.10 elevado a sexta potência ciclos. O limite de fadiga determinado experimentalmente foi comparado com as previsões do modelo GT e do Método do Ponto, um dos métodos da chamada Teoria da Distância Crítica (TDC). No modelo GT foram considerados três métodos: GTc-p, GTs-e e GTquebra, segundo o método usado para achar o fator geométrico para determinar o fator de intensidade de tensão. As previsões dos modelos GTc-p, GTquebra e TDC são similares no caso de entalhes com raios de ponta grandes, e bem próximas do limite de fadiga medido experimentalmente, enquanto que eles são não-conservativos no caso de entalhes afiados (raios de ponta pequenos). As previsões do modelo GTs-e foram conservativas para entalhes afiados e não afiados. Devido a que os dois modelos são baseados em conceitos lineares elásticos, foi demonstrado que uma análise elástica apresenta limitações para modelar o comportamento à fadiga em entalhes afiados, pois nesses casos a tensão local no ponto crítico pode exceder o limite de escoamento do material. Alem disso, o modelo GT também permite estimar o tamanho da maior trinca curta não-propagante (TCNP) associada ao limite de fadiga. Tais TCNP foram monitoradas nas faces do C(T) através de técnicas não-destrutivas tais como microscopia óptica, correlação digital de imagens e tomografia; enquanto que as TCNP internas foram detectadas usando a técnica destrutiva da metalografia. Os tamanhos das TCNP detectadas foram muito menores do que as estimadas pelo modelo GT, dificultando ainda mais o problema de detecção daquelas trincas. / [en] The mechanical design of structural components for high cycle fatigue applications needs reliable fatigue limits. However, mainly because of notches and the unavoidable presence of small defects, such a task still presents some challenges. Notches cause a stress concentration effect that can initiate short cracks at their tips, but such short cracks may propagate or become non-propagating, depending not only on the load level, but on the stress gradient ahead of the notch tip as well. Notch-like defects, such as scratches, pores, and inclusions, behave in the same way. There are empirical and theoretical models to predict the fatigue limit of notched components. The latter includes the so-called Stress Gradient (SG) model, based on linear elastic fracture mechanics concepts and using the El Haddad-Topper-Smith (ETS) characteristic size aR, as a promissory approach. However, there is a lack of experimental data verifying their fatigue limit predictions. In this context, C(T)-like notched specimens of SAE 1020 steel with several notch root radii were tested under constant load amplitude control at 40 Hz and a stress ratio R equal 0.1, to evaluate their fatigue limit through accelerated tests involving step loading procedures with blocks of 3.10 to sixth power cycles. The experimental fatigue limit was compared with values predicted by SG model, following three approaches: SGc-p, SGs-e, and SGquebra, according to the determination of the geometric factor of the stress concentration factor; and with an alternative prediction by the Point Method based on the theory of critical-distance (TCD). SGc-p, SGquebra and TCD model predictions are almost coincident for blunt notches and they present a good agreement with experimental results, but they are non-conservatives in the case of sharp notches; while SGc-p predictions are conservative for both blunt and sharp notches. Since both models are based on linear elastic concepts, it was demonstrated that an elastic analysis presents limitations to model the behavior of short cracks emanating from sharp notches, due to the local stress at the critical point can exceed the yield strength of the material. Furthermore, according to SG model, the fatigue limit is related to the presence of non-propagating short cracks (NPSC). Such surface NPSCs on the face of the specimens were monitored by non-destructive techniques including optical microscopy, digital image correlation (DIC) and micro-computed tomography; whereas subsurface NPSCs were detected through destructive metallographic technique. The sizes of the detected NPSCs were much smaller than those values predicted by SG model, which in turn makes the detection of these cracks a more complex problem.

Submitted by ANA CLAUDIA SILVA BRAGA null (anabragga@gmail.com) on 2017-08-31T16:15:53Z No. of bitstreams: 1 Tese Doutorado Ana Claudia Silva Braga.pdf: 4552779 bytes, checksum: 456de4a6fbfd60347292d8755d6c8c47 (MD5) / Approved for entry into archive by Luiz Galeffi (luizgaleffi@gmail.com) on 2017-09-01T14:16:37Z (GMT) No. of bitstreams: 1 braga_acs_dr_sjrp.pdf: 4552779 bytes, checksum: 456de4a6fbfd60347292d8755d6c8c47 (MD5) / Made available in DSpace on 2017-09-01T14:16:37Z (GMT). No. of bitstreams: 1 braga_acs_dr_sjrp.pdf: 4552779 bytes, checksum: 456de4a6fbfd60347292d8755d6c8c47 (MD5) Previous issue date: 2017-08-04 / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / O vírus da hepatite C (HCV) causa a doença da Hepatite C e estima-se que cerca de 3% da população mundial esteja infectada com o vírus. A infecção por HCV promove a alteração na expressão de várias proteínas celulares. Estudos têm demonstrado que muitas proteínas de choque térmico (HSPs) possuem um perfil de expressão alterado na presença do vírus e algumas HSPs interagem diretamente com proteínas do HCV. Assim, o presente estudo teve como objetivo avaliar in vitro os níveis de expressão de proteínas de choque térmico na presença e ausência de HCV. Com este propósito, células de hepatoma humano Huh7.5 e células Huh7.5 infectadas com o vírus (HCV JFH-1) foram submetidas à extração de RNA e síntese de cDNA. A expressão diferencial de 84 HSPs e chaperonas foi avaliada por qPCR Array. Os resultados demonstram que cinco genes apresentaram expressão aumentada (em Log2 2), enquanto outros cinco apresentaram expressão reduzida. Para validar estes resultados os 10 genes diferencialmente expressos foram testados por qPCR em três modelos celulares para o HCV: células contendo replicon subgenômico do HCV (SGR-JFH-1), células infectadas com JFH-1 (ambos do genótipo 2a) e células contendo o replicon subgenômico S52 (genótipo 3). O gene HSPB8 mostrou expressão aumentada nos três modelos testados, condizente com os resultados obtidos por qPCR Array. Em seguida, promovemos o silenciamento de HSPB8 e foi observado um aumento na replicação viral. Em contraste, quando aumentamos a expressão de HSPB8, o HCV teve uma diminuição na taxa de replicação. O mesmo procedimento foi adotado para o gene DNAJC5B, validado no modelo viral genótipo 3, e o HCV mostrou padrão de replicação semelhante ao observado para o gene anterior. Esses resultados sugerem que HSPB8 pode atuar como um fator intracelular contra a replicação do vírus da hepatite C e DNAJC5B apresenta a mesma função, mas específico para o genótipo 3. Também avaliamos interações diretas com proteínas do HCV e os resultados demonstraram uma interação física entre a proteína NS4B de HCV e HSPB8. Esses resultados podem contribuir para uma melhor compreensão dos mecanismos envolvidos na replicação do HCV. / Hepatitis C virus (HCV) causes Hepatitis C disease and it is estimated that about 3% of world population are infected with the virus. HCV infection promotes alteration in the expression of several cellular proteins. Studies have shown that many heat shock proteins (HSPs) have an altered expression profile in the presence of the virus and some HSPs interact directly with HCV proteins. Thus, the present study aimed to evaluate in vitro the expression levels of heat shock proteins in the presence and absence of HCV. With this purpose, human hepatoma Huh7.5 cells and Huh7.5 cells infected with the virus (HCV JFH-1) were subjected to RNA extraction and cDNA synthesis. The differential expression of 84 HSPs and chaperones was assessed by qPCR Array. The results demonstrate that five genes showed increased expression (over Log2 2), while five other presented reduced expression. To validate these results, the 10 differentially expressed genes were tested by real-time PCR in three different HCV cell culture models: subgenomic HCV replicon cells (SGR-JFH-1), JFH-1 infected cells (both genotype 2a) and subgenomic S52 cells (genotype 3). The HSPB8 gene showed increased expression in all of three tested models, consistent with qPCR Array results. Then we promoted the silencing of HSPB8 and observed an increase in viral replication. In contrast, when we increased an expression of HSPB8, HCV had a decrease in replication rate. The same procedure was adopted for the DNAJC5B, validated in the viral model genotype 3, and HCV showed replication pattern similar to that observed for the previous gene. These results suggest that HSPB8 may act as an intracellular factor against hepatitis C virus replication and DNAJC5B have the same function, but genotype 3 specific. We also evaluated direct interactions with HCV proteins and the results demonstrated a physical interaction between the HCV NS4B protein with HSPB8. These results can contribute for a better understanding of the mechanisms involved in HCV replication. / FAPESP: 2013/17253-9

Atualmente, a Leucemia Linfocítica Crônica (LLC) pode ser dividida em dois grupos: um com mutações somáticas no gene da região variável da cadeia pesada da imunoglobulina (MIgVH) e outro sem mutações (NMIgVH). Alguns estudos mostraram que a expressão de CD38 na superfície das células B de LLC pode estar correlacionada com o estado mutacional do gene VHIg, entretanto, esses controversos. Estudos recentes mostraram que a expressão da proteína tirosina quinase Zap-70 está melhor associada com o estado mutacional do gene IgVH. O objetivo deste estudo foi avaliar a expressão de Zap-70 e CD38, por citometria de fluxo, nas células CD19+ de pacientes com LLC e correlacioná-los com o estádio clínico (EC), sobrevida livre de tratamento (SLT) e sobrevida global (SG). A expressão de Zap-70 e CD38 foi avaliada, em 144 de pacientes com LLC classificados nos estádios clínicos A, B e C de acordo com os critérios de Binet: 59 (41%) do EC-A, 38 (26%) do EC-B e 47 (33%) do EC-C. Foi observada menor positividade para Zap-70 e CD38 nos pacientes do EC-A do que nos EC-B e C. Quando avaliada a SLT nos pacientes do EC-A, os casos Zap-70+ assim como os CD38+ apresentaram menor SLT. A média de SG dos pacientes Zap-70+ e CD38+ foi menor quando comparado com os Zap-70- e CD38- entretanto quando correlacionada com o EC não foi observada diferença estatisticamente significante entre a expressão desses marcadores e o EC-A, B ou C. Pela analise combinada de CD38 e Zap-70, dividimos os pacientes em dois grupos (Zap-70-/CD38- e Zap-70+ ou CD38+). Observamos que a expressão positiva desses dois marcadores estava associada ao EC, uma vez que a grande maioria dos pacientes dos estádios B (74%) e C (66%) expressam Zap-70 ou CD38. Entretanto, os pacientes do EC-A, Zap-70+ ou CD38+, apresentaram SG menor quando comparado com os Zap-70-/CD38-. Essa diferença não foi observada nos pacientes do EC-B e do EC-C. Também foi observada menor SLT nos pacientes no EC-A, Zap-70+ ou CD38+. Esses resultados sugerem que análise combinada de Zap-70 e CD38 podem ser empregadas na avaliação dos pacientes do EC-A para se acompanhar a evolução clinica desse grupo de pacientes. Porém, estudos adicionais devem ser realizados para se validar a utilização clínica desses marcadores. / Actually, chronic lymphocytic leukemia (CLL) can be divided in two subsets: one with somatically mutated immunoglobulin heavy-chain variable-region genes (MIgVH) and other with unmutated sequences. (UMIgVH). Some studies have shown that CD38 expression in CLL cells are correlated with IgVH mutational status. However, the value of CD38 as surrogate IgVH mutational status is controversial. Recent studies, have found that Zap-70 protein tyrosine kinase expression is strongly associated with the mutational status IgVH. The aim of this study was to evaluate the Zap-70 and CD38 expression, for flow cytometry, in CD19+ LLC cells and correlate with the Binet’s staging system, treatment-free survival (TFS) and a overall survival (OS). Zap-70 and CD38 was evaluated, in 144 CLL patients that was classified in A, B and C Binet’s staging system: 59 (41%) in stage A, 38 (26%) in B and 47 (33%) in C. We observed low Zap-70 and CD38 expression in stage A patients than in stage B and C cases. When we analyzed the TFS in stage A patients Zap-70+ and CD38+ patients showed shorter TFS than Zap-70- and CD38-. Then we observed that the OS of Zap-70+ and CD38+ patients was, also, shorter than Zap-70- and CD38- cases. However, statistical differences was not found when Zap-70 and CD38 expression was correlated with stage A, B or C Binet’s staging system. To understand the associated Zap-70 and CD38 expression, we divided the CLL patients in two subgroups (Zap-70-/CD38 - and Zap-70+ or CD38+). We observed that CD38+ or Zap-70+ was associated Binet’s staging system, once most of stage B (74%) and C (66%) patients are Zap-70+ or CD38+. However, stage A patients, Zap-70+ or CD38+, showed shorter OS than Zap-70-/CD38-. These differences were not observed in stage B and C patients. Shorter TFS was also observed in the Zap-70+ or CD38+ stage A patients. These results suggest that combined analysis of Zap-70 and CD38 can be used to evaluate stage A patients to observe the clinical evolution of the disease. Nevertheless, other studies must be carried to confirm the clinical use of these markers.

No description available.

Open-source software is in average used in more than 65% of the applications within the domains of enterprise software, retail and e-commerce, cybersecurity and internet of things (Synopsys, 2019). With the frequent use of open-source software, security issues arise which need to be handled. These include among other issues; non-patched vulnerabilities and malicious code (Schryen, 2011). Security guidelines for open-source software usage have been defined by numerous security organizations as an effort to increase effective security handling of open source software within organizations. These guidelines often cover directives on many layers of an organization and are often lacking information necessary for them to be understandable, reliable, and useful to the person using them.The purpose of this study is to contribute to increased software security related to open-source software usage, by exploring and providing information on the topic, and by defining a set of improved security guidelines that cover both what measures to take to minimize security risks, and how to implement it, based on the published state-of-the-art security guidelines for using open-source software.The subject was investigated through a research process focused on answering whether the current state-of-the-art security guidelines could be improved, using a qualitative research type based on a document analysis data collection method. The research was exploratory in its design and the main focus was to explore the subject by trying to answer the posed research question.By investigating the state of contemporary security guidelines found in literature, and evaluating them against a set of desirable attributes for high quality guidelines, it became evident that the contemporary guidelines couldbe improved. An effort was therefore made to build on the found guidelines and improve them by trying to resolve the issues found through the evaluation.The effort of trying to improve existing guidelines resulted in a new set of guidelines including added information and reformulations, however, the changes made could not be said to be conclusive or objective improvements. Instead they present suggestions for how and in what aspects the contemporary guidelines could be improved. / Mjukvara med öppen källkod (open-source software) används i genomsnitti mer än 65% av applikationerna för mjukvara till företag, detaljoch e-imageimageimageimagehandel, cybersäkerhet och sakernas internet (Synopsys, 2019). Den frekventa användningen av öppen källkod ger upphov till säkerhetsrisker som behöver motverkas. Dessa risker inkluderar bland annat; skadlig kod och säkerhetsbrister som inte åtgärdas (Schryen, 2011). Säkerhetsriktlinjer har blivit definierade av ett flertal organisationer med målet att effektivisera säkerhetshanteringen av öppen källkod och på så sätt minska risken för attacker. Dessa riktlinjer täcker ofta många olika delar av en organisations hierarki och saknar ofta information som är nödvändig för att göra dem begripliga, pålitliga och användbara för de personer som använder dem. Syftet med denna studieär att bidra till enökad säkerhet vid användan-det av öppen källkod genom att dels öka kunskapen om ämnet, och genom att definiera en samling förbättrade säkerhetsriktlinjer som både beskriver vad som ska göras för att minska säkerhetsrisker och hur det ska göras. De förbättrade riktlinjerna ska baseras på befintliga säkerhetsriktlinjer för användning av öppen källkod. Ämnet studerades genom en forskningsprocess med fokus på att besvara frågan om huruvida befintliga säkerhetsriktlinjer kan förbättras, där information samlades in genom en kvalitativ forskningstyp baserad på dokumentanalys. Forskningsdesignen var av utforskande karaktär, där huvudfokuset låg i att utforska ämnet genom att försöka besvara forskningsfrågan.Genom att undersöka kvalitén av befintliga säkerhetsriktlinjer som hittats i litteraturen och utvärdera dessa med stöd av en stor samling önskvärda egenskaper hos riktlinjer av hög kvalitet, blev det uppenbart att befintliga riktlinjer kan förbättras. Däför genomfördes ett försök att vidareutveckla befintliga riktlinjer för att förbättra dem genom att lösa de problem som hittats genom utvärderingen. Försöket att förbättra existerande riktlinjer resulterade i en ny uppsättning riktlinjer med tillagd information och omformuleringar. Dessa förändringar kan dock inte sägas representera konklusiva eller objectiva förbättringar. Istället representerar de förbättrade riktlinjerna ett förslag på hur riktlinjer skulle kunna förbättras.

No description available.

No description available.

The South African context, in particular, is characterized by a definite need for the facilitation of the development of the youth in a more positive trajectory. Family structures are not always robust enough to support the positive development of the youth, owing to the demands made on single–parent families, amongst other reasons. Community structures may also be less supportive of the development of the youth, because of the impact of the changes associated with the transitional phase of the country during the past sixteen years (Meehan, Peirson & Fridjhon, 2007). Furthermore, young people under the age of 15 years comprise almost a third of the total South African population (Statistics South Africa, 2009), and in the future, they will have to be prepared for an adulthood faced with previously unknown challenges (United Nations Population Fund). The importance of the development of the youth, in order to enable them to contribute to their country in future, is acknowledged by the South African Governement (National Youth Commission website). This study was conducted within the parameters of the newly developing positive youth development (PYD) paradigm. The empirical level of this paradigm is well represented in the literature, indicating that the content areas, or the “what” of PYD, have been well elucidated. However, there is a lack of theory, especially with regard to models describing developmental change (Larson et al., 2004), and evaluation of interventions aiming at the facilitation of PYD. In order to contribute to the answering of the questions regarding the “how” of development, this study had the following main aims: a) the compilation of a theoretical model, describing developmental change in the youth; b) the operationalization of this model for intervention purposes; and c) the evaluation of a programme and the model on which it is based. The study is reported on in an article format, and comprises a total of three articles. The first article focuses on the process of the compilation of a theoretical model by means of: a) the construction of a comprehensive meta–theoretical matrix, b) the integration of theory that features in the PYD literature, and c) the expansion of the latter with theory from other compatible sub–disciplines in psychology. The resultant Positive Youth Development Intervention (PYDI) model provides a process–related description of developmental change ? and is one of the first models to do so. The second article describes the operationalization of the PYDI model, by means of an indication of the relevant constructs, phenomena and processes to be facilitated. Although recent research points to a relation between PYD and self–regulation, there has been no model, describing the role of self–regulation in the facilitation of the positive development of the youth. This study adapted a model from an educational context (Heckhausen & Gollwitzer, 1987 (as cited in Boekaerts & Niemivirta, 2005)), in order to describe the regular self–regulatory processes constituting the bi–directional interactions between the youth and their primary life contexts, as proposed by developmental systems theory (Lerner, 1998), the meta–theory to PYD (King et al., 2005). A further specifc contribution is that the presentation aspects of the programme material, aimed at facilitating the integration thereof, are addressed on a theoretical level. The third article describes the evaluation of the PYDI model and programme, with young adolescents in a school in a rural area as participants. A mixed–methods study, which has been shown to render much richer information than a quantitative study alone, was applied. Although the quantitative data did not prove the success of the programme, the qualitative data suggested that some aspects of self–regulation had indeed been facilitated successfully. A second follow–up assessment, conducted seventeen months later, indicated that certain skills had only become internalized by that time, suggesting that the implementation and evaluation of such a programme should be expanded over an extended time–frame. This study has contributed to the level of theory of PYD, by indicating, a) the lacunae, and b) that theory in compatible sub–disciplinary paradigms could be used in order to devise workable models for PYD. Furthermore, the process–related nature of the PYDI model and programme, owing to its adaptability to different needs, may be adapted and extended to be applicable to the needs of the diverse South African population. Recommendations regarding future application and research, especially within the South African context, have also been put forward in the study. / Thesis (Ph.D. (Psychology))--North-West University, Potchefstroom Campus, 2011.