A widespread and persistent memory error that people commit on a daily basis is the post-completion error (PCE; i.e., forgetting to complete the final step of a procedural task). PCEs occur in the railroad industry when a locomotive conductor changes the direction of a rail switch but fails to report this change. This particular error could contribute to unsafe conditions as another train traveling on the same track could derail. Although training can help reduce some of the factors leading to unsafe conditions on the rail, research has demonstrated that PCEs are different from other errors of omission in that they cannot be eliminated through training, which makes them a difficult problem to address. Therefore, there is a need to explore new remedial actions designed to reduce PCEs. The current study investigated the effectiveness of a theoretically motivated intervention at reducing PCEs in trainyard operations, where making these errors could be life-threatening. Twenty-eight undergraduates completed trainyard tasks within a high-fidelity simulator. Each participant received the behavioral intervention in one block and no intervention in another. Specifically, participants were required to perform an additional task designed to remind participants of the post-completion (PC) step. The intervention significantly reduced PCE rates in the context of trainyard operations, on average, by 65%. We discuss implications of these results on reducing trainyard accidents, and how this outcome can contribute to the literature on the cause of PCEs.

Introduction: There are currently no established guidelines to determine which cases general practitioners should refer to an endodontist for root canal treatment. The American Association of Endodontists (AAE) has developed the EndoCase mobile application (ECA), which utilizes either a full or abridged rubric to assign case difficulty level and provide referral guidelines to general practitioners and dental students. Objective: The objective of this study was to determine whether the abridged criteria of the EndoCase application can help predict the incidence of procedural errors in nonsurgical root canal treatment of mandibular molars in an undergraduate dental clinic based on the difficulty level. Methods: A list of patients who received primary root canal treatment on mandibular first molars in the undergraduate dental clinic from 2015-2020 was obtained. Ninety patients qualified for inclusion. Case difficulty level was assessed using the ECA by three providers with differing levels of experience. Incidence of procedural errors was determined from post-operative radiographs by two calibrated independent observers. Results: The most common endodontic mishaps were errors during access cavity preparation followed by the presence of voids in the root filling, with an incidence of 54.4% and 45.6%, respectively. There were no significant differences regarding case difficulty level and the incidence of total procedural errors nor number of treatment visits. Of the individual error types, the presence of obturation >2mm short of the radiographic apex was weakly correlated with case difficulty level (r = 0.226, pConclusion: There is minimal correlation between the difficulty level of mandibular molars determined by the ECA and the number of treatment visits or overall incidence of procedural errors.

A presente Dissertação de Mestrado tem por escopo o exame das nulidades no processo penal brasileiro. O estudo foca, em especial, o prejuízo, critério eleito pelo ordenamento jurídico brasileiro para verificar quando há, ou não, nulidade, tendo em vista a adoção da teoria da instrumentalidade das formas. Escolheu-se estudar o tema, em razão da falta de uniformidade no tratamento da matéria, tanto em nível doutrinário quanto jurisprudencial. Com efeito, é possível notar que são proferidas decisões divergentes para casos iguais, em curto espaço de tempo. Entre os fatores que podem, eventualmente, explicar essa carência de sistematização está o fato de não se conseguir especificar e/ou bem delimitar: (a) qual o conceito e o cerne da nulidade, sobretudo processual, (b) qual sua natureza jurídica, (c) como a nulidade pode ser diferenciada dos demais institutos jurídicos, haja vista existir muita confusão entre as nulidades e as demais invalidades, sem contar o instituto da inexistência jurídica. No que tange ao prejuízo, não há consenso a seu respeito, qual o seu conteúdo, bem como se dá a sua ocorrência no processo, se precisa ser efetivo (concreto), ou meramente potencial. Todas essas questões têm trazido muitas dúvidas tanto na teoria quanto na prática, havendo uma grande insegurança jurídica, o que pode levar a decisões casuísticas, acarretando tratamentos diferenciados para casos iguais: o que enseja, de um lado, impunidade (ou tratamento privilegiado) e, de outro, persecuções penais arbitrárias, vulnerando o sistema de direitos e garantias no Estado de Direito Democrático. O estudo é feito, ao final, à luz da jurisprudência do Supremo Tribunal Federal e do Superior Tribunal de Justiça, pois é somente a partir dessa análise que se conseguirá melhor esmiuçar quais critérios e balizas têm sido levados em conta para, em cada caso concreto, reconhecer-se o prejuízo e, por via reflexa, a nulidade. O presente estudo, ainda que de maneira audaciosa, tem a pretensão de propor uma maior sistematização da matéria, almejando a aplicação equânime e justa do direito. / This Master\'sDissertation aims to analyze annulments in the Brazilian criminal proceeding. The instant Research focuses on the harm rule, the legal standard chosen by the Brazilian system to check whether there is a kind of nullity in the criminal proceeding, considering the instrumentality theory of legal forms. The subject was chosen due to the lack of uniformity: both in academic area (doctrinaire) and in the judicial practice. Indeed, there exist different kinds of decisions for similar cases, in short periods of time. Among the reasons that could possibly explain this lack of systematization or this difference of treatment is the fact that scholars and the justices are not able to specify and/or even to define properly: (a) the essence of the concept or the core of the proceeding invalidity and, particularly (b) its legal constitution as well as (c) how the nullity can be distinguished from other legal institutions that are alike, also considering that there is too much confusion between the nullity and the other kinds of invalidities, including a lot of misunderstanding between the invalidity and the legal non-existence theory. Regarding specifically the harm rule, the scholars and the Courts also do not clarify for instance, what it is and its content is, as well as how its occurrence takes in the criminal law proceeding: if it must be effective (concrete) or merely potentially. All these non-solution issues have brought many questions to both theory and practice, and there is considerable legal uncertainty, which may lead casuistic decisions, bringing different treatments which can lead impunity (or preferential treatment) and on to other hand arbitrary acts against the defendant, violating human rights. The study is done in light of the decisions of the Supreme Court and the Superior Court of Justice, because this analysis allows to elaborate the criteria and goals taken into account, to assess properly the harm rule and the nullity. The present study also dares to propose a better systematization of the issue, always taking into consideration the desired and the necessary fair enforcement of law.

The study aimed to explore misconceptions that Grade 9 learners at a school in Soweto had concerning the topic of fractions. The study was based on the ideas of constructivism in a bid to understand how learners build on existing knowledge as they venture deeper into the development of advanced constructions in the concept of fractions. A case study approach (qualitative) was employed to explore how Grade 9 learners describe the concept of fractions. The approach offered a platform to investigate how Grade 9 learners solve problems involving fractions, thereby enabling the researcher to discover the misconceptions that learners have/display when dealing with fractions. The research allowed the researcher to explore the root causes of the misconceptions held by learners concerning the concept of fractions. Forty Grade 9 participants from a township school were subjected to a written test from which eight were purposefully selected for an interview. The selection was based on learners’ responses to the written test. The researcher was looking for a learner script that showed application of similar but incorrect procedures under specific sections of operations of fractions, for example, multiplication of fractions. Both performance extremes were also considered, the good and the worst performers overall. The written test and the interviews were the primary sources of data in this study. The study revealed that learners have misconceptions about fractions. The learners’ definitions of what a fraction is were neither complete nor precise. For example, the equality of parts was not emphasised in their definitions. The gaps brought about by the learner conception of fractions were evident in the way problems on fractions were manipulated. The learners did not treat a fraction as signifying a specific point on the number system. Due to this, learners could not place fractions correctly on the number line. Components of the fraction were separated and manipulated as stand-alone whole numbers. Consequently, whole number knowledge was applied to work with fractions. A lack of conceptual understanding of equivalent fractions was evident as the common denominator principle was not applied. In the multiplication of fractions, procedural manipulations were evident. In mixed number operations, whole numbers were multiplied separately from the fractional parts of the mixed number. Fractional parts were also multiplied separately, and the two answers combined to yield the final solution. In the division of fractions, the learners displayed a lack of conceptual knowledge of division of fractions. Operations were made across the division sign numerators separate from the denominators. This reveals that a fraction was not taken as an outright number on its own by learners but viewed as one number put on top of the other which can be separated. Dividing across, learners rendered division commutative. A procedural attempt to apply the invert and multiply procedure was also evident in this study. Learners made procedural errors as they showed a lack of conceptual understanding of the keep-change-flip division algorithm. The study revealed that misconceptions in the concept of fraction were due to prior knowledge, over-generalisation and presentation of fractions during instruction. Constructivism values prior knowledge as the basis for the development of new knowledge. In this study, learners revealed that informal knowledge they possess may impact negatively on the development of the concept of fractions. For example, division by one-half was interpreted as dividing in half by learners. The prior elaboration on the part of a whole sub-construct also proved a barrier to finding solutions to problems that sought knowledge of fractions as other sub-constructs, namely, quotient, measure, ratio and fraction as an operator. Over generalisation by learners in this study led to misconceptions in which a procedure valid in a particular concept is used in another concept where it does not apply. Knowledge on whole numbers was used in manipulating fractions. For example, for whole numbers generally, multiplication makes bigger and division makes smaller. The presentation of fractions during instruction played a role in some misconceptions revealed by this study. Bias towards the part of a whole sub-construct might have limited conceptualisation in other sub-constructs. Preference for the procedural approach above the conceptual one by educators may limit the proper development of the fraction concept as it promotes the use of algorithms without understanding. The researcher recommends the use of manipulatives to promote the understanding of the fraction concept before inductively guiding learners to come up with the algorithm. Imposing the algorithm promotes the procedural approach, thereby depriving learners of an opportunity for conceptual understanding. Not all correct answers result from the correct line of thinking. Educators, therefore, should have a closer look at learners’ work, including those with correct solutions, as there may be concealed misconceptions. Educators should not take for granted what was covered before learners conceptualised fractions as it might be a source of misconceptions. It is therefore recommended to check prior knowledge before proceeding with new instruction. / Mathematics Education / M. Ed. (Mathematics Education)