<p>U disertaciji je elaborirana mogućnost primene relaksirajućih otvora kod istiskivanja delova sa ozubljenjem u cilju smanjenja parametara procesa. Primenjena su dva modela deformisanja, kada je otvor u pripremku i kada je otvor u žigu. Metodom gornje granice izvr&scaron;ena je teorijska analiza procesa i kreirano re&scaron;enje na osnovu koga su određeni deformaciona sila, pritisak na žig i promena geometrije dela. Pomoću eksperimenta istiskivanja i numeričke simulacije procesa izvr&scaron;ena je verifikacija teorijskog re&scaron;enja. Teorijski, eksperimentalni i rezultati simulacije procesa su pokazali da primena relaksirajućih otvora na analizirane tipove ozubljenja dovodi do smanjenja deformacione sile i pritiska u procesu.</p> / <p>Possibility of flow relief openings applying in cold extrusion of gear-like elements in order to reduce the process parameters is elaborated in this thesis. Two different deformation models are analysed: when the opening is in the billet and when the opening is in the punch. Upper bound method was applied for the process analysis and determination of deformation force, punch pressure and change of part geometry. Extrusion experiment and numerical simulation of process are used for verification of theoretical solution. Theoretical, experimental and numerical results confirmed that application of flow relief openings enables reduction of deformation force and punch pressure in the process of gear-like elements extrusion.</p>

The growing use of information and communication technologies (ICTs) in college campuses has dramatically increased the potential for multitasking among students who have to juggle classes, school assignments, work, and recreational activities. These students believe that they have become more efficient by performing two or more tasks simultaneously. The use of technology, however, has changed the student’s ability to focus and attend to what they need to learn. Research has shown that multitasking divides students’ attention, which could have a negative impact on their cognition and learning. The purpose of this study was to examine the effects of distractive multitasking on students’ attention and academic performance in a classroom setting. Several studies in cognitive psychology have focused on individuals’ divided attention between simultaneously occurring tasks. Such research has found that, because human attention and capacity to process information are selective and limited, a performance decrement often results when task performance requires divided attention. Distractive tasks are defined as tasks or activities for which cognitive resources are used to process information that is not related to the course material. Multitasking is defined as the engagement in individual tasks that are performed in succession through a process of context switching. Using a non-experimental, correlational research design, the researcher examined the effects of distractive multitasking, with computer devices, during classroom lectures, on students’ academic performance. This study used a monitoring system to capture data that reflected actual multitasking behaviors from students who used computers while attending real-time classroom lectures. The findings showed that there was no statistically significant relationship between the frequency of distractive multitasking (predictor variable) and academic performance (criterion variable), as measured by the midterm and final evaluation scores. The results did not support the hypothesis that distractive computer-based multitasking could have a negative impact on academic performance.

L'objectif de cette thèse est de déterminer l'impact de la distraction du conducteur et de la consommation d'alcool, ainsi que leurs interactions, sur les performances des conducteurs novices. Des mesures subjectives des comportements à risques et des performances objectives sur simulateur de conduite sont recueillies. Une première expérience étudie les déterminants psycho-sociaux de la prise de risque et le type de comportements à risques rapportés par les jeunes conducteurs. La seconde expérience s'intéresse aux performances lors d'une tâche d'attention divisée sur simulateur de conduite en fonction de l'expérience, de l'âge et du type d'apprentissage suivi. Enfin, la troisième expérimentation a pour objectif d'étudier l'impact de faible et forte dose d'alcool sur les performances de jeunes conducteurs, novices et expérimentés, lors d'une tâche d'attention divisée. Ces recherches permettent d'approfondir nos connaissances sur les mécanismes d'actions de la distraction et de l'alcool sur les performances du conducteur, en particulier des novices. / The aim of this thesis is to investigate the effects of driver distraction by a secondary task, alcohol consumption and their interaction on performance depending on driving experience. Objective and subjective measures are recorded. The first experience studies the determinants of risk-taking and the kind of risky driving behaviour recalled by young drivers. Differences depending on driving experience, sex, and initial training show an increment of driving risk-taking for young drivers with 3 years of driving experience and with traditional training. The aim of the second experiment is to study the effects of a divided attention task on performance depending on driving experience, age and initial training. Novice drivers have more difficulties to divide their attention between two tasks than experienced drivers, notably when one of these tasks is complex or located in peripheral vision. The third experiment studies the negative impact of alcohol (low and high doses) on young drivers' performances, novice and experienced, during a divided attention task. The classical detriment effect of alcohol on driving performance is replicated, and this effect is more pronounced for novice drivers who adopt a risky driving behaviour under the influence of alcohol, even with a low dose of alcohol. This research improves our fundamental knowledge on how distraction and alcohol impair drivers' performance, notably when they are novice.

Estudos prévios têm indicado a capacidade de aprender diferentes movimentos simultaneamente, sugerindo que a aprendizagem motora pode ocorrer a partir de uso parcial de recursos atencionais. Porém, não se conhece a extensão em que a aprendizagem em tarefas motoras duais é afetada pela distribuição da atenção entre as tarefas durante a prática. O objetivo deste estudo foi avaliar o efeito da distribuição de diferentes proporções da atenção a cada componente de uma tarefa motora dual durante a prática sobre sua aprendizagem e automatização. Participaram deste estudo 35 estudantes universitários, destros, que realizaram as seguintes tarefas: traçar uma estrela baseada em feedback visual invertido com a mão esquerda e realizar toques sequenciais dos dedos com a mão direita. A execução simultânea das duas tarefas correspondeu à tarefa dual. Para estimar a demanda de atenção para execução das tarefas foi realizada a medida de tempo de reação probatório com estímulo auditivo e resposta vocal. Os participantes foram divididos em três grupos: prática na tarefa dual com distribuição assimétrica de atenção, alocando maior atenção à tarefa de traçado de estrela e mínima atenção à tarefa de toques dos dedos (Dass); prática na tarefa dual com atenção distribuída simetricamente entre ambas as tarefas (Dsim); e prática na tarefa singular, com prática exclusiva na tarefa de traçado (Sing). Os resultados mostraram que os três grupos diminuíram o tempo de reação probatório nos desempenhos das tarefas singulares e dual, indicando ganho de automatização com a prática. Na tarefa de toques dos dedos, os grupos Dsim e Dass tiveram melhor desempenho do que o grupo Sing, indicando que esta tarefa foi aprendida com baixa alocação de atenção. Na tarefa de traçado de estrela, os três grupos melhoraram de forma similar o desempenho com a prática. A avaliação na tarefa dual revelou que ambos os grupos de prática na tarefa dual, independentemente da distribuição de atenção, tiveram melhor desempenho após a prática em relação ao grupo Sing. Não foram encontradas diferenças entre os grupos Dsim e Dass tanto para a tarefa de toques dos dedos quanto para a tarefa de traçado de estrela, indicando que estas tarefas foram aprendidas de forma equivalente para diferentes regimes de distribuição de atenção. Estes resultados sugerem que a melhora de desempenho com a prática, e automatização de movimentos associada, pode ser atingida com alocação de recursos atencionais parciais durante a prática na tarefa / Previous studies have indicated the human ability to learn different movements simultaneously, suggesting that motor learning can be achieved from partial use of attentional resources. However, the extent to which learning dual motor tasks is affected by the distribution of attention between tasks during practice is unknown. The aim of this study was to evaluate the effect of distribution of different proportions of attention to each component of a dual motor task during practice on its learning and automaticity. Thirty-five right-handed university students participated of the study. They performed the following tasks: drawing of a star-shaped figure based on inverted visual feedback with their left hand and sequentially touching the fingers with their right hand. The dual task consisted of the simultaneous execution of the two tasks. To evaluate movement\'s automatization due to practice, we used a probe reaction time task consisting of an auditory stimulus and a vocal response. Participants were assigned to one of three groups: practice of the dual task with asymmetric distribution of attention, allocating major attentional resources to the star drawing task and minimal attention to the fingers touching task (Dasy); practice of the dual task with symmetric distribution of attention between both tasks (Dsym); and practice of the single star drawing task (Sing). Results showed that after practice, the probing reaction time was reduced in the performance of the single and dual tasks in all groups, indicating augmented automaticity after practice. In the fingers touching task, the Dsym and Dasy groups outperformed the Sing group, indicating that this task was learned with reduced attention. In the star drawing task, the three groups improved similarly their performance after practice. Evaluation of the dual task revealed that both dual task practice groups, independently of the attention distribution regime, performed better than the Sing group after practice. No differences were found between the Dsym and Dasy groups across tasks, suggesting that they learned to a similar extent both tasks regardless of the attention distribution regime. These results suggest that performance improvement from practice, and associated movements automatization, can be achieved with allocation of partial attentional resources during the task acquisition

Durante o turno de trabalho em atividades repetitivas, foram avaliados 8 homens com idade entre 20 e 40 anos, com cronotipo moderadamente matutino, e dominância manual e visual direita. Os sujeitos foram submetidos a testes de alocação da atenção visual 6 vezes ao dia, em 9 dias. Os testes consistiam em manter o olhar fixo no centro da tela do computador, e responder o mais rapidamente possível a todos os estímulos que aparecerem. No experimento 1 (atenção explícita) devia-se prestar particular atenção à área de 4ox4o centrada no ponto de fixação, no experimento 2 (atenção dividida) devia-se prestar atenção simultaneamente a duas regiões de 4ox4o centradas lateralmente, a 10 o do centro. Os voluntários executaram a primeira tarefa sem problemas durante todo o turno de trabalho, com TRs médios mais rápidos no início da manhã (7h40min), e no início da tarde (14h20min). Quanto aos testes de atenção dividida, houve uma aparente oscilação no desempenho médio dos sujeitos a cada uma hora e vinte, com TRs mais rápidos nos mesmos horários (7:40 e 14:20). / During their worshift with repetitive activity, we evaluated 8 male subjects between 20 and 40 years old, right eye and hand dominance, and with moderate morningness chronotype. The subjects were submitted to tests of allocation of visual attention on 9 days. Tests consisted of fixing the point center of a computer screen and pressing a key as quickly as possible to any stimulus that they appeared anywhere on the screen. In experiment 1 attentioni should be focussed in a 4ox4o central area, whereas in experiment 2, attention should be divided simultaneously sideways, in two such 4ox4o areas, indicated by two lateral squares frames. Subjects easily focused attention in the center (experiment 1) throughout their workshift, whit quicker average of reaction times (RTs) at the beginning of the morning (7h40min), and at the beginning in the afternoon (14h20min). There was, on the other hand, an apparent oscillation in their ability to divide attentio with period of approximately 80 min. Again, mean RTs were faster at 7:40 and again at 14:20.

Estudos prévios têm indicado a capacidade de aprender diferentes movimentos simultaneamente, sugerindo que a aprendizagem motora pode ocorrer a partir de uso parcial de recursos atencionais. Porém, não se conhece a extensão em que a aprendizagem em tarefas motoras duais é afetada pela distribuição da atenção entre as tarefas durante a prática. O objetivo deste estudo foi avaliar o efeito da distribuição de diferentes proporções da atenção a cada componente de uma tarefa motora dual durante a prática sobre sua aprendizagem e automatização. Participaram deste estudo 35 estudantes universitários, destros, que realizaram as seguintes tarefas: traçar uma estrela baseada em feedback visual invertido com a mão esquerda e realizar toques sequenciais dos dedos com a mão direita. A execução simultânea das duas tarefas correspondeu à tarefa dual. Para estimar a demanda de atenção para execução das tarefas foi realizada a medida de tempo de reação probatório com estímulo auditivo e resposta vocal. Os participantes foram divididos em três grupos: prática na tarefa dual com distribuição assimétrica de atenção, alocando maior atenção à tarefa de traçado de estrela e mínima atenção à tarefa de toques dos dedos (Dass); prática na tarefa dual com atenção distribuída simetricamente entre ambas as tarefas (Dsim); e prática na tarefa singular, com prática exclusiva na tarefa de traçado (Sing). Os resultados mostraram que os três grupos diminuíram o tempo de reação probatório nos desempenhos das tarefas singulares e dual, indicando ganho de automatização com a prática. Na tarefa de toques dos dedos, os grupos Dsim e Dass tiveram melhor desempenho do que o grupo Sing, indicando que esta tarefa foi aprendida com baixa alocação de atenção. Na tarefa de traçado de estrela, os três grupos melhoraram de forma similar o desempenho com a prática. A avaliação na tarefa dual revelou que ambos os grupos de prática na tarefa dual, independentemente da distribuição de atenção, tiveram melhor desempenho após a prática em relação ao grupo Sing. Não foram encontradas diferenças entre os grupos Dsim e Dass tanto para a tarefa de toques dos dedos quanto para a tarefa de traçado de estrela, indicando que estas tarefas foram aprendidas de forma equivalente para diferentes regimes de distribuição de atenção. Estes resultados sugerem que a melhora de desempenho com a prática, e automatização de movimentos associada, pode ser atingida com alocação de recursos atencionais parciais durante a prática na tarefa / Previous studies have indicated the human ability to learn different movements simultaneously, suggesting that motor learning can be achieved from partial use of attentional resources. However, the extent to which learning dual motor tasks is affected by the distribution of attention between tasks during practice is unknown. The aim of this study was to evaluate the effect of distribution of different proportions of attention to each component of a dual motor task during practice on its learning and automaticity. Thirty-five right-handed university students participated of the study. They performed the following tasks: drawing of a star-shaped figure based on inverted visual feedback with their left hand and sequentially touching the fingers with their right hand. The dual task consisted of the simultaneous execution of the two tasks. To evaluate movement\'s automatization due to practice, we used a probe reaction time task consisting of an auditory stimulus and a vocal response. Participants were assigned to one of three groups: practice of the dual task with asymmetric distribution of attention, allocating major attentional resources to the star drawing task and minimal attention to the fingers touching task (Dasy); practice of the dual task with symmetric distribution of attention between both tasks (Dsym); and practice of the single star drawing task (Sing). Results showed that after practice, the probing reaction time was reduced in the performance of the single and dual tasks in all groups, indicating augmented automaticity after practice. In the fingers touching task, the Dsym and Dasy groups outperformed the Sing group, indicating that this task was learned with reduced attention. In the star drawing task, the three groups improved similarly their performance after practice. Evaluation of the dual task revealed that both dual task practice groups, independently of the attention distribution regime, performed better than the Sing group after practice. No differences were found between the Dsym and Dasy groups across tasks, suggesting that they learned to a similar extent both tasks regardless of the attention distribution regime. These results suggest that performance improvement from practice, and associated movements automatization, can be achieved with allocation of partial attentional resources during the task acquisition

O objetivo geral da presente tese foi investigar possíveis efeitos da atenção dividida da memória implícita perceptual não-verbal e verbal, e conceitual na fase de recuperação. Foram realizados dois estudos teóricos e um empírico. O primeiro estudo teórico teve o objetivo de revisar sistematicamente pesquisas que avaliaram o papel da atenção em testes de memória implícita (priming de repetição) com o paradigma da atenção dividida, na fase de codificação ou de recuperação. Foram selecionados 31 artigos empíricos com base em critérios pré-estabelecidos. Concluiu-se que os primings, perceptual e conceitual, são afetados pela atenção dividida na codificação quando a tarefa secundária demanda mais atenção, isto é, quando exige resposta frequente e é apresentada sincrônica ao estímulo alvo de memória. Poucos estudos foram realizados na fase de recuperação e indicaram imunidade desses primings à atenção dividida. O segundo estudo buscou apresentar e discutir aspectos metodológicos relevantes à elaboração de experimentos usando priming de repetição, com ênfase na seleção de materiais (software, listas de estímulos normatizados para o Brasil e relevância de fatores psicolinguísticos) e manipulação de variáveis (calibração pré-experimental, instruções e tempo de exposição dos estímulos, por exemplo). Recomendações para pesquisas futuras foram apresentadas. O artigo empírico foi o terceiro estudo e incluiu três experimentos. Os experimentos exploraram o papel da atenção na memória implícita perceptual não verbal e expandiram os resultados com testes perceptual e conceitual verbal, avaliando os efeitos da atenção dividida em novas condições experimentais. O experimento 1 utilizou o teste implícito de completar fragmentos de figuras com uma tarefa secundária de julgamento de tons; o experimento 2 utilizou completar radical de palavra e o experimento 3, produção de exemplar da categoria, ambos com uma tarefa secundária de julgamento de sequências de consoantes. Os resultados evidenciaram que a memória implícita foi afetada pela atenção dividida nos testes de completar fragmentos de figura e produção de exemplar da categoria, enquanto completar radical de palavra foi imune aos efeitos da divisão da atenção. Coletivamente, os resultados indicaram que, sob algumas circunstâncias, memória implícita perceptual exige recursos atencionais na recuperação. Recursos atencionais são exigidos pela memória implícita conceitual, tal como hipotetizado na literatura. / The general aim of this thesis was to investigate the role of attention in nonverbal perceptual implicit memory and expand knowledge on perceptual implicit memory and verbal conceptual. Two theoretical studies and one empirical were performed. The first theoretical study systematized research that evaluated the role of attention in implicit memory tests (repetition priming) with the paradigm of divided attention in encoding or retrieval phase. A total of 31 empirical articles based on pre-established criteria. The conclusion was that the primings, perceptual and conceptual, are affected by divided attention in encoding when the secondary task demands more attention, that is, when requires frequent response and it is presented synchronously to the memory target stimulus. Few studies was conducted in the retrieval phase and indicated that the primings are immune to divided attention. The second theoretical study aimed to present and discuss methodological aspects relevant to the elaboration of experiments using repetition priming, with emphasis on the selection of materials (software, standardized stimuli lists for Brazil and relevance of psycholinguistic factors) and variable manipulation (pre-calibration experimental, instructions and exposure time of the stimuli, for example). Recommendations for future research are presented. The empirical paper was the third study and included three experiments. The experiments explored the role of attention in nonverbal perceptual implicit memory and expanded the results with perceptual tests and verbal conceptual, evaluating the effects of divided attention on new experimental conditions. Experiment 1 used the implicit picture fragment completion test with a secondary task of judgment tones; Experiment 2 used word stem completion and the experiment 3, exemplary production category, both with a secondary task of judgment consonant sequences. The results showed that implicit memory was affected by divided attention in picture fragment completion and category exemplar production, while word stem completion was immune to the effects of divided attention. Collectively, the results indicated that, under some circumstances, perceptual implicit memory requires attentional resources in recovery. Attentional resources are required by the conceptual implicit memory, as hypothesized in the literature.

This thesis examines the institutional design and the procedures regulating the decree-making in the poleis of the Classical and Hellenistic periods. The main contention of this thesis is that Greek decree-making is to be conceived as the result of a multi-layered system of interaction and delegation of deliberative authority among different institutions: councils, officials, assemblies and lawcourts. My thesis argues, therefore, that decree-making procedures were specifically designed to implement the concept of 'divided power', a value shared by both democracies and non-democratic regimes, and to shape the collective behaviour of the citizens when acting as decision-makers within the institutions. By adopting models from the political sciences, my thesis bridges the gap between institutional approaches to political decision-making and more recent approaches that have stressed the role of values and ideology as key factors to understand ancient Greek politics. Chapter 1 lays out the methodology of the thesis informed by the New Historical Institutionalism. Chapter 2 analyses the practice of delegation of power from the Athenian Assembly to the Athenian Council in order to enact additional measures. The careful study of the delegation-clauses sheds light on the administrative power of the Council by demonstrating that the Council played a proper policy-making role through the enactment of a decree, which was the product of Council's expertise in defined matters, such as religious affairs, foreign policy and the navy. Chapter 3 builds on the findings of the previous chapter, and shows the workings and development of delegation-clauses to the Council in two examples from outside Athens, Mytilene and Megalopolis over the longue durée. Chapter 4 deals with the deliberative procedures of Hellenistic Sparta. The Spartan 'divided power' envisaged that the Gerousia shared the probouleutic power with the ephors who could independently submit the bill to the Assembly. The Gerousia, however, held the power of nomophylakia and could veto the final decree. This chapter shows that divided power and the need of legal stability were addressed by Spartan institutions, but with different results because of the wider powers of officials in the decree-making. This chapter introduces the important issue of the balance between people's deliberation and stability of the legal order, which form an important focus of chapters 5 and 6. Chapter 5 discusses the role played by legal procedure of the adeia in fifth-century deliberative decision-making in the Assembly. This chapter provides a new comprehensive account of this legal institution. Adeia instituted a pre-nomothetic procedure, according to which the Assembly could change an entrenched piece of legislation or decree without clashing with the nomothetic ideology. Chapter 6 examines the relationship between deliberation and judicial review in the Greek poleis. The first section discusses the Athenian graphe paranomon, the public charge against an illegal decree. A thorough analysis of the legal procedure and of the institutional design shows that deliberative decisions were made within the framework of the rule of law and the graphe paranomon enforced this principle. This did not imply an institutional prominence of the lawcourts in the Athenian decision-making. The lawcourts performed an important role in the deliberative process through providing a safeguard of legal consistency by adding the legal expertise of the judges to the general rationale of the decree-making. The second part of the chapter is dedicated to the discussion of evidence of judicial review from outside Athens and the multifaceted role of the Hellenistic practice of appointing foreign judges in adjudicating public lawsuits, and especially in the judicial review of decrees.

The purpose of this study was to examine interference between concurrently performed speaking and driving tasks. Participants included 60 adults, 30 males and 30 females, with no history of communication disorders. They were divided into three different age groups of 20 participants each: younger (20s), middle-aged (40s), and older (60s). The participants were given a list of topics to consider and were instructed to select eight topics that they could talk about; they completed five practice trials of the driving simulator prior to the experimental recording to eliminate practice effects. Each participant completed the speaking task and driving task both separately and concurrently. The speaking task consisted of producing a monologue about the topics that they had selected. Dependent measures for speech included metrics relating to intensity, fundamental frequency, and the ratio of speaking to pausing time. The simulated driving task involved maintaining a constant speed and lane position on a freeway. Dependent measures for driving included metrics relating to speed, lane position, steering wheel position, and a count of steering wheel turns. Results indicated significant divided attention effects in speaking time ratio, intensity, speed, and steering wheel control. There was a significant age effect for intensity and fundamental frequency as the younger group had less variation with these variables compared to the other age groups. There was a significant age effect for lane position, steering wheel position, and speed as the younger group had less variation in lane and position compared to the other groups and the older group had more variation in speed and steering wheel position compared to the other groups. There was a significant gender effect for intensity and lane position as the females had less variation in intensity and more variation in lane position compared to the males. These findings suggest that divided attention conditions impact both speech and driving performance. The results also shed some light on the effects of age on concurrently performed speech and driving tasks. These findings imply that divided attention conditions should be incorporated in treatment to help patients generalize the skills learned in therapy to everyday communication.

This paper looks to examine how the Dayton Peace Agreement (1995) was meant to create a stable, unified Bosnia and Herzegovina versus what was actually achieved. The institutional rules of Dayton were designed to check and balance the three ethnic groups, yet the country is defined by political division rather than cooperation. The international community, prescribed by Dayton to oversee and enforce Bosnia’s transition, has supported a flawed institutional design. The theories of consociationalism, centripetalism, and the prevalence of the ethno-territorial principle are used to explain how Dayton has failed in facilitating cooperation and moderation. The impact of the prolonged, involved role of the High Representative and the European Court of Human Right's 2009 case, Sejdić and Finci, are used as analysis. I argue that Dayton’s institutional design has allowed ethnic division to define BiH's political system and the prolonged intervention of the High Representative has removed incentive for local elites to cooperate.