Thesis (M.Eng.(Mechanical and Aeronautical Engineering))--University of Pretoria, 2008. / Includes bibliographical references.

[pt] Nos últimos anos, polímeros conjugados ganharam muita atenção na eletrônica orgânica por seu uso na fabricação de dispositivos flexíveis e de baixo custo. Como resultado, diferentes tipos de dispositivos têm sido desenvolvidos como: diodos emissores de luz orgânicos (OLEDs), células fotovoltaicas orgânicas (OPVs) e transistores de efeito de campo orgânicos (OFETs). Em particular, para os OFETs seu desempenho depende da interface isolante/semicondutor, principalmente, devido ao acúmulo de portadores de carga. Além disso, as propriedades da interface afetam fortemente o transporte de carga através do canal de dispositivo. Por estas razões, a pesquisa de novos polímeros semicondutores e novos materiais dielétricos é um fator chave para aprimorar o desempenho dos dispositivos. Neste trabalho, os polímeros PMMA, PVA, FORMVAR e PU foram investigados como materiais dielétricos. Inicialmente foram fabricados capacitores de placas planas paralelas do tipo ITO/dielétrico/Al para determinar a constante dielétrica dos isolantes, as curvas JxV e a capacidade por unidade de área. Desenvolveu-se OFETs tipo Top-Gate/Bottom-Contacts (TGBC) com a estrutura Au/P3HT/PMMA/Ag e Au/P3HT/PU/Ag. No trabalho, a espessura dos dielétricos foi variada para aprimorar o desempenho dos dispositivos. Para os OFETs de PMMA obteve-se resultados concordantes com os da literatura. Os novos OFETs de PU apresentaram tensões de operação menores que 5V, que é um requisito para a integração destes OFETs em aplicações da eletrônica orgânica. A mobilidade obtida nestes OFETs de PU foi de 1.25 cm(2)/V.s, com uma tensão limiar de 0.02 e uma razão On/Off de 100. / [en] In the last years, conjugated polymers have received much attention in organic electronics for their use in the fabrication of low cost and flexible devices. As a result, different types of devices have been developed e.g. organic light emitting diodes (OLEDs), photovoltaic devices (OPVs) and field effect transistors (OFETs). For the OFETs in particular, their performance depends primarily on insulator/semiconductor interface, mainly due to charge carrier accumulation. Moreover, the interface properties strongly affect the charge transport through the device channel. For these reasons, the research for new semiconductor polymers and new dielectric materials is key to advancing the performance improvement of devices. In this work, the polymers PMMA, PVA, FORMVAR and PU were used as dielectric materials. Initially, parallel plate capacitors of the structure ITO/dielectric/A1 were made, in order to determine the dielectric constant of the insulators, get the curves JxV and the capacity per unit area. It was used to develop Top-Gate/Bottom-Contacts (TGBC) OFETs with structures of Au/P3HT/PMMA/Ag and Au/P3HT/PU/Ag. The thicknesses of the dielectric materials were varied to improve the performance of the devices. For the PMMA OFETs, the results obtained were concordant with those of the existing literature. The new PU OFETs presented with operating voltages of less than 5V, appropriate for applications of these OFETs in organic electronics. The mobility of the PU OFETs was 1.25cm(2)/V.s, the threshold voltage 0.02V and the On/Off ratio 100.

[pt] O objetivo deste trabalho é verificar qual dentre as teorias de Trade-Off e Pecking Order predomina nos anos de crise financeira para explicar a forma como empresas brasileiras de capital aberto tomam suas decisões de financiamento. No Brasil, quatro crises financeiras relevantes aconteceram no período de 1998 até 2016: as crises de 1999, 2002, 2008 e 2015. A decisão da estrutura de capital das empresas tem implicações no valor de mercado da companhia e seu custo de capital. Por esse motivo, os estudos sobre a estrutura de capital têm se apresentado como um dos temas mais estudados e relevantes na área de finanças corporativas. Dentre as teorias estudadas, existem duas correntes teóricas que discutem como as empresas determinam sua estrutura de capital: a teoria de Trade-Off e a teoria de Pecking Order. Desta forma, inicialmente foram verificadas quebras estruturais no nível de alavancagem das empresas brasileiras de capital aberto nos anos de crises financeiras mencionados e, em seguida, aplicado o modelo de Tong e Green (2005) de regressão múltipla em cross section, a fim de verificar qual teoria melhor explica as decisões de financiamento das empresas nesses anos. / [en] The objective of this study is to verify which of the theories - trade-off or pecking order - prevails in the years of financial crisis to explain how Brazilian publicly held companies make their financing decisions. In Brazil, four major financial crises occurred from 1998 to 2016: the crises of 1999, 2002, 2008 and 2015. A company s decision on its capital structure is important because the composition of its different financing sources has implications for its market value and cost of capital. For this reason, capital structure has been one of the most studied and relevant topics in corporate finance. Among the theories studied, there are two theoretical currents that discuss how companies determine their capital structure: trade-off theory and pecking order theory. Thus, a methodology was initially applied to verify the existence of a structural break in the level of leverage of Brazilian publicly traded companies in those previously mentioned years of financial crises. Later, a model of multiple regression in cross section, based on Tong and Green (2005) was applied, in order to verify which theory best explains the financing decisions of the companies in those years.

La fusion nucléaire est une solution technologique prometteuse pour une nouvelle source d'énergie. Cependant, utiliser la par fusion nucléaire confinement magnétique comme source d'énergie constitue un challenge scientifique et technologique car cela requière à la fois un bon confinement du plasma de cœur et un contrôle des flux de chaleurs arrivant à la paroi. Ce travail est motivé par la problématique de la gestion des flux de chaleur dans les réacteurs de fusion. Cela est nécessaire pour éviter d'endommager les coûteux composants faisant face au plasma. La compréhension des mécanismes physiques régissant le transport de la chaleur dans le plasma de bord est une tâche critique pour le design des futures machines. Dans ce contexte, il est nécessaire de faire des prédictions fiables de l'étalement de la chaleur dans le but de dimensionner correctement ces futures machines. Cela appelle à un fondement théorique décrivant la manière dont l'énergie s'échappe du plasma. Des études théoriques et expérimentales ont tenté aboutir à cette fin, cependant les mécanismes en jeux ne sont toujours pas clairs. Pour atteindre ce but, la modélisation numérique est un complément nécessaire aux expériences. Ce travail de thèse est dédié à l'étude numérique des différents aspects du transport de la chaleur dans le plasma de bord un utilisant les approches fluides. Une attention particulière est porté à deux mécanismes suspectés de joué un grand rôle dans le transport de la chaleur : le transport intermittent due à la turbulence et le transport convectif à large échelle par les vitesses dérives. Le problème a été traité avec une approche graduelle en utilisant différent outils numériques. / Fusion devices are a promising solution for a new source of energy. However, using fusion reaction to produce power within a magnetic confinement is a scientific and technological challenge as it requires a high confinement in the core plasma at the same time as a good control of plasma exhaust on the material walls. This work is motivated by the key problematic of power handling in fusion power plants necessary to avoid damaging the expensive plasma facing components (PFC). The understanding of the physics underlying the heat transport, and more specifically is a critical task for the engineering design of future Tokamak devices. In this context, it is mandatory to make reliable predictions of the power spreading in order to correctly size the future Tokamaks. This calls for a theoretical ground describing the way energy escapes the core plasma through the separatrix and deposits on the PFCs. Some theoretical and experimental studies attempt to achieve such a task, however no definitive conclusion have been drawn yet. To achieve this goal, numerical modelling is a necessary complement to experimental results. This PhD work has been dedicated to the study of the different aspects of the heat transport in the edge plasma using a numerical fluid approach. Special focus was devoted to two types of mechanisms suspected to play an important role in the heat transport: intermittent turbulence; the large-scale convective transport.

Syfte: Dagens samhälle blir mer och mer energimedvetet och regeringen sätter upp riktlinjer för bland annat byggsektorn i form av nya regler från Boverket. Ett av den svenska regeringens mål för klimat- och energipolitiken är att till år 2020 minska klimatutsläppen med 40 % och energianvändningen ska vara 20 % effektivare än i dagsläget. Ett led i detta är att bygga byggnader som är mer energieffektiva eller till och med tillverkar sin egen energi. Byggbranschen i Sverige står i dagsläget för cirka 40 % av koldioxidutsläppen, majoriteten av utsläppen sker vid producering av energi som tillförs byggnaderna under brukningsskedet. Målet för arbetet är att granska lönsamheten hos off-grid-förskolor i en mindre kommun i Mellansverige ur ett ekonomiskt perspektiv. Metod: Arbetet är en fallstudie som undersöker projektering av förskolor som planerar byggas i en mindre kommun i Mellansverige. Förskolan ska vara självförsörjande på energi genom att ha solceller på taket tillsammans med vätgasbränsleceller. Med det systemet ska hela byggnadens energibehov kunna tillgodoses. Intervjuer genomförs med de aktörer som ska bygga förskolan, både från beställarsidan och utförarsidan. Dokumentanalys av bygghandlingar används för att göra en LCC-analys som jämför den planerade energikällan mot bergvärme och passivhus. Resultat: Det är inte ekonomiskt lönsamt att använda vätgasbränslecell med solceller som energikälla. LCC-analysen indikerar att det inte är lönsamt att investera i vätgasbränsleceller som energikälla eftersom initialkostnaden är så hög att den inte går att ta igen ekonomiskt under byggnadens livstid jämfört med de andra två alternativ som undersökts. Formfaktorn är bra men det finns utrymme för förbättringar främst i minskad fönsterarea och en mer kvadratisk byggnad som leder till minskad väggarea och därmed lägre byggpris. Både LCC-analysen och intervjuerna indikerar att vätgasbränsleceller är en dyr teknik i dagsläget. Det behövs fler satsningar från politiskt håll för att få igång debatt om bränsleceller och skapa förutsättningar för att företag och privatpersoner ska kunna satsa på tekniken. Det kan dock vara lönsamt för en kommun på andra sätt, till exempel genom att ny industri och fler jobb lockas till kommunen. Konsekvenser: Slutsatsen är att det i dagsläget inte verkar vara lönsamt med vätgasbränslecell som energikälla. Ämnet behöver studeras i större perspektiv där den nya industrin som genereras av kommunens satsning på vätgasbränsleceller tas i beaktning. Begränsningar: Studien utgår från det planerade projektet i Mariestads kommun och har inte jämförts med några andra liknande projekt. Studien tittar på initial- och driftkostnader och tar inte med miljöaspekten i värderingen om lönsamhet. / Purpose: Today’s society is becoming more and more energy conscious and the government sets guidelines for, inter alia, the construction sector in the form of new regulations by the Boverket. One of the Swedish government´s goals for climate and energy policy is to reduce climate emissions by 40% and 20% more efficient energy use than now. A part of this is to build buildings that are more energy efficient or even produce their own energy. The construction industry is Sweden currently accounts for about 40% of the carbon dioxide emissons, the majority of emissions occur in the production of energy supplied to buildings during the use phase. The aim of the work is to review the profitability of off-grid preschools in a small municipality in central Sweden from an economic perspective. Method: This study is a case study that investigates the planned project of kindergartens in a smaller municipality in mid-Sweden. The kindergarten is supposed to be off-grid, self-sustained, in energy using photo voltaic cells on the roof together with hydrogen fuel cells. With this system the entire energy need of the building will be provided. Interviews are performed with participants of the project, both client and contractor. A document analysis is used to make an LCC analysis that compares the intended energy source with a geothermal one and zero energy building. Findings: It is not economically profitable to use hydrogen fuel cell in conjunction with photo voltaic cells as an energy source. The LCC analysis indicates that it is not profitable to invest in hydrogen fuel cells as an energy source since the initial cost is so high that it can´t be recouped within the life span of the building compared to the two other options investigated. The form factor is good but there is room for improvements especially in cut window area and a square shaped building that leads to smaller wall area and therefore less expensive building. Both the LCC analysis and the interviews indicate that hydrogen fuel cells as of today is an expensive technique. More political engagement is required to start debate about fuel cells and to create conditions for companies and individuals to be able to invest in the technique. It can however be profitable for a municipality in other ways, i.e. new industries and more jobs in the municipality. Implications: The conclusion is that it is not economically profitable to use hydrogen fuel cells as an energy source. The subject needs to be studied in a greater context considering the new industries generated by the municipality’s investment in hydrogen fuel cells. Limitations: The study generates from the planned project in Mariestads municipality and has not compared with other similar projects. The study investigates initial costs and maintenance costs and does not consider the environmental aspect in profitability.

Objetivos: Descrever o uso e determinar a prevalência de medicamentos potencialmente perigosos e de uso off label e não aprovados em prescrições de unidades de pediatria geral de um hospital universitário no sul do Brasil. Método: Estudo transversal, realizado de novembro de 2007 a janeiro de 2008, envolvendo pacientes até 14 anos de idade, com período de internação superior a 24 horas. Pacientes de unidades de terapia intensiva e oncologia pediátrica foram excluídos. A classificação quanto aos critérios de aprovação da Food and Drug Administration foi realizada pela fonte terciária DrugDex-Micromedex e a classificação dos potencialmente perigosos, pelo Institute for Safe Medication Practices. Resultados e discussão: No período de estudo foram analisadas 342 prescrições de 342 pacientes. O sexo masculino foi o mais freqüente (57%) e mais da metade dos pacientes já apresentavam doenças crônicas à internação. Analgésicos foi a classe terapêutica mais prescrita (26,9%) e entre os off label, os antiespasmódicos (31,5%) foram os mais prevalentes. Das prescrições analisadas, aproximadamente 39% tiveram pelo menos um medicamento de uso off label prescrito, principalmente em relação à indicação terapêutica (38,4%) e à idade (21,9 %), e 11,8% dos pacientes fizeram uso de fármacos não aprovados. Do total de itens (2026), cerca de 6% foram classificados como potencialmente perigosos, destacando-se os analgésicos opióides (35%). Não houve relação de associação entre medicamentos de uso off label e os potencialmente perigosos. Conclusão: As frequências encontradas de medicamentos off label e não aprovados estão de acordo com a literatura e podem ser consideradas elevadas. Os potencialmente perigosos, apesar da baixa prevalência, oferecem risco pelos efeitos prejudiciais que possam vir a causar nos pacientes. Assim, os medicamentos em destaque neste estudo representam uma preocupação constante em hospitais. / Objectives: Describe the use and determine the prevalence of high-alert medications, off label use and unlicensed drugs in prescriptions of general pediatric units of a university hospital in southern Brazil. Method: Cross-sectional study, performed from November 2007 to January 2008, involving patients up to 14 years of age, with admission period over 24 hours. Patients of intensive care and pediatric oncology units were excluded. The classification regarding the Food and Drug Administration approval criteria was performed according to the DrugDex-Micromedex tertiary source and the classification of high-alert medications according to the Institute for Safe Medication Practices. Results e discussion: In the study period, 342 prescriptions were analyzed. Males were more frequent (57%) and over half of the patients already presented chronic diseases for admission. Analgesic drugs were the most frequently prescribed therapeutic class of drugs (26.9%) and among the off-label drugs, antispasmodic drugs (31.5%) were the most prevalent. Around 39% of the analyzed prescriptions had at least one off-label use drug, especially in relation to therapeutic indication (38.4%) and age (21.9%), and 11.8% of the patients received unlicensed drugs. About 6% of the total items (2026) were classified as high-alert medications, such as opioid analgesic drugs (35%). No relation of association was observed between off-label use and high-alert medications. Conclusion: The frequency analyses found of off-label and unlicensed drugs are according to the literature and can be considered as high. The high-alert medications, although of low prevalence, offer risks due to negative effects that can occur in patients. Then, the drugs highlighted in this study constitute a constant concern in hospitals.

This thesis aims to design a test equipment for positive change the adhesion contact between the wheel and the rail head. This can be achieved by changing the size of the coefficient of friction, which are eliminated negative effects accompanying the operation of the rail transport (acoustic emissions and excessive wear). Reducing friction must not be compromised traction or braking. Equipment ranks among to Top of Rail systems where as medium is used the friction modifier. The study includes an overview of available types of friction modifiers and applicators Top of rail system. The design of the applicator is built based on the off-board system that is placed in front of the arc track with a small radius of curvature.

Objetivos: Descrever o uso e determinar a prevalência de medicamentos potencialmente perigosos e de uso off label e não aprovados em prescrições de unidades de pediatria geral de um hospital universitário no sul do Brasil. Método: Estudo transversal, realizado de novembro de 2007 a janeiro de 2008, envolvendo pacientes até 14 anos de idade, com período de internação superior a 24 horas. Pacientes de unidades de terapia intensiva e oncologia pediátrica foram excluídos. A classificação quanto aos critérios de aprovação da Food and Drug Administration foi realizada pela fonte terciária DrugDex-Micromedex e a classificação dos potencialmente perigosos, pelo Institute for Safe Medication Practices. Resultados e discussão: No período de estudo foram analisadas 342 prescrições de 342 pacientes. O sexo masculino foi o mais freqüente (57%) e mais da metade dos pacientes já apresentavam doenças crônicas à internação. Analgésicos foi a classe terapêutica mais prescrita (26,9%) e entre os off label, os antiespasmódicos (31,5%) foram os mais prevalentes. Das prescrições analisadas, aproximadamente 39% tiveram pelo menos um medicamento de uso off label prescrito, principalmente em relação à indicação terapêutica (38,4%) e à idade (21,9 %), e 11,8% dos pacientes fizeram uso de fármacos não aprovados. Do total de itens (2026), cerca de 6% foram classificados como potencialmente perigosos, destacando-se os analgésicos opióides (35%). Não houve relação de associação entre medicamentos de uso off label e os potencialmente perigosos. Conclusão: As frequências encontradas de medicamentos off label e não aprovados estão de acordo com a literatura e podem ser consideradas elevadas. Os potencialmente perigosos, apesar da baixa prevalência, oferecem risco pelos efeitos prejudiciais que possam vir a causar nos pacientes. Assim, os medicamentos em destaque neste estudo representam uma preocupação constante em hospitais. / Objectives: Describe the use and determine the prevalence of high-alert medications, off label use and unlicensed drugs in prescriptions of general pediatric units of a university hospital in southern Brazil. Method: Cross-sectional study, performed from November 2007 to January 2008, involving patients up to 14 years of age, with admission period over 24 hours. Patients of intensive care and pediatric oncology units were excluded. The classification regarding the Food and Drug Administration approval criteria was performed according to the DrugDex-Micromedex tertiary source and the classification of high-alert medications according to the Institute for Safe Medication Practices. Results e discussion: In the study period, 342 prescriptions were analyzed. Males were more frequent (57%) and over half of the patients already presented chronic diseases for admission. Analgesic drugs were the most frequently prescribed therapeutic class of drugs (26.9%) and among the off-label drugs, antispasmodic drugs (31.5%) were the most prevalent. Around 39% of the analyzed prescriptions had at least one off-label use drug, especially in relation to therapeutic indication (38.4%) and age (21.9%), and 11.8% of the patients received unlicensed drugs. About 6% of the total items (2026) were classified as high-alert medications, such as opioid analgesic drugs (35%). No relation of association was observed between off-label use and high-alert medications. Conclusion: The frequency analyses found of off-label and unlicensed drugs are according to the literature and can be considered as high. The high-alert medications, although of low prevalence, offer risks due to negative effects that can occur in patients. Then, the drugs highlighted in this study constitute a constant concern in hospitals.

L'analyse et la compréhension du comportement d'applications parallèles sur des plates-formes de calcul variées est un problème récurent de la communauté du calcul scientifique. Lorsque les environnements d'exécution ne sont pas disponibles, la simulation devient une approche raisonnable pour obtenir des indicateurs de performance objectifs et pour explorer plusieurs scénarios ``what-if?''. Dans cette thèse, nous présentons un environnement pour la simulation off-line d'applications écrites avec MPI. La principale originalité de notre travail par rapport aux travaux précédents réside dans la définition de traces indépendantes du temps. Elles permettent d'obtenir une extensibilité maximale puisque des ressources hétérogènes et distribuées peuvent être utilisées pour obtenir une trace. Nous proposons un format dans lequel pour chaque événement qui apparaît durant l'exécution d'une application, nous récupérons les informations sur le volume d'instructions pour une phase de calcul ou le nombre d'octets et le type d'une communication. Pour obtenir des traces indépendantes du temps lors de l'exécution d'applications MPI, nous devons les instrumenter pour récupérer les données requises. Il existe plusieurs outils d'instrumentation qui peuvent instrumenter une application. Nous proposons un système de notation qui correspond aux besoins de notre environnement et nous évaluons les outils d'instrumentation selon lui. De plus, nous introduisons un outil original appelé Minimal Instrumentation qui a été conçu pour répondre au besoins de notre environnement. Nous étudions plusieurs méthodes d'instrumentation et plusieurs stratégies d'acquisition. Nous détaillons les outils qui extraient les traces indépendantes du temps à partir des traces d'instrumentations de quelques outils de profiling connus. Enfin nous évaluons la procédure d'acquisition complète et présentons l'acquisition d'instances à grande échelle. Nous décrivons en détail la procédure pour fournir un fichier de plateforme simulée réaliste à notre outil d'exécution de traces qui prend en compte la topologie de la plateforme cible ainsi que la procédure de calibrage par rapport à l'application qui va être simulée. De plus, nous montrons que notre simulateur peut prédire les performances de certains benchmarks MPI avec moins de 11% d'erreur relative entre l'exécution réelle et la simulation pour les cas où il n'y a pas de problème de performance. Enfin, nous identifions les causes de problèmes de performances et nous proposons des solutions pour y remédier. / Analyzing and understanding the performance behavior of parallel applicationson various compute infrastructures is a long-standing concern in the HighPerformance Computing community. When the targeted execution environments arenot available, simulation is a reasonable approach to obtain objectiveperformance indicators and explore various ``what-if?'' scenarios. In thiswork we present a framework for the off-line simulation of MPIapplications. The main originality of our work with regard to the literature is to rely on\tit execution traces. This allows for an extreme scalability as heterogeneousand distributed resources can be used to acquire a trace. We propose a formatwhere for each event that occurs during the execution of an application we logthe volume of instructions for a computation phase or the bytes and the type ofa communication. To acquire time-independent traces of the execution of MPI applications, wehave to instrument them to log the required data. There exist many profilingtools which can instrument an application. We propose a scoring system thatcorresponds to our framework specific requirements and evaluate the mostwell-known and open source profiling tools according to it. Furthermore weintroduce an original tool called Minimal Instrumentation that was designed tofulfill the requirements of our framework. We study different instrumentationmethods and we also investigate several acquisition strategies. We detail thetools that extract the \tit traces from the instrumentation traces of somewell-known profiling tools. Finally we evaluate the whole acquisition procedureand we present the acquisition of large scale instances. We describe in detail the procedure to provide a realistic simulated platformfile to our trace replay tool taking under consideration the topology of thereal platform and the calibration procedure with regard to the application thatis going to be simulated. Moreover we present the implemented trace replaytools that we used during this work. We show that our simulator can predictthe performance of some MPI benchmarks with less than 11\% relativeerror between the real execution and simulation for the cases that there is noperformance issue. Finally, we identify the reasons of the performance issuesand we propose solutions.

Objetivos: Descrever o uso e determinar a prevalência de medicamentos potencialmente perigosos e de uso off label e não aprovados em prescrições de unidades de pediatria geral de um hospital universitário no sul do Brasil. Método: Estudo transversal, realizado de novembro de 2007 a janeiro de 2008, envolvendo pacientes até 14 anos de idade, com período de internação superior a 24 horas. Pacientes de unidades de terapia intensiva e oncologia pediátrica foram excluídos. A classificação quanto aos critérios de aprovação da Food and Drug Administration foi realizada pela fonte terciária DrugDex-Micromedex e a classificação dos potencialmente perigosos, pelo Institute for Safe Medication Practices. Resultados e discussão: No período de estudo foram analisadas 342 prescrições de 342 pacientes. O sexo masculino foi o mais freqüente (57%) e mais da metade dos pacientes já apresentavam doenças crônicas à internação. Analgésicos foi a classe terapêutica mais prescrita (26,9%) e entre os off label, os antiespasmódicos (31,5%) foram os mais prevalentes. Das prescrições analisadas, aproximadamente 39% tiveram pelo menos um medicamento de uso off label prescrito, principalmente em relação à indicação terapêutica (38,4%) e à idade (21,9 %), e 11,8% dos pacientes fizeram uso de fármacos não aprovados. Do total de itens (2026), cerca de 6% foram classificados como potencialmente perigosos, destacando-se os analgésicos opióides (35%). Não houve relação de associação entre medicamentos de uso off label e os potencialmente perigosos. Conclusão: As frequências encontradas de medicamentos off label e não aprovados estão de acordo com a literatura e podem ser consideradas elevadas. Os potencialmente perigosos, apesar da baixa prevalência, oferecem risco pelos efeitos prejudiciais que possam vir a causar nos pacientes. Assim, os medicamentos em destaque neste estudo representam uma preocupação constante em hospitais. / Objectives: Describe the use and determine the prevalence of high-alert medications, off label use and unlicensed drugs in prescriptions of general pediatric units of a university hospital in southern Brazil. Method: Cross-sectional study, performed from November 2007 to January 2008, involving patients up to 14 years of age, with admission period over 24 hours. Patients of intensive care and pediatric oncology units were excluded. The classification regarding the Food and Drug Administration approval criteria was performed according to the DrugDex-Micromedex tertiary source and the classification of high-alert medications according to the Institute for Safe Medication Practices. Results e discussion: In the study period, 342 prescriptions were analyzed. Males were more frequent (57%) and over half of the patients already presented chronic diseases for admission. Analgesic drugs were the most frequently prescribed therapeutic class of drugs (26.9%) and among the off-label drugs, antispasmodic drugs (31.5%) were the most prevalent. Around 39% of the analyzed prescriptions had at least one off-label use drug, especially in relation to therapeutic indication (38.4%) and age (21.9%), and 11.8% of the patients received unlicensed drugs. About 6% of the total items (2026) were classified as high-alert medications, such as opioid analgesic drugs (35%). No relation of association was observed between off-label use and high-alert medications. Conclusion: The frequency analyses found of off-label and unlicensed drugs are according to the literature and can be considered as high. The high-alert medications, although of low prevalence, offer risks due to negative effects that can occur in patients. Then, the drugs highlighted in this study constitute a constant concern in hospitals.