‘High’-School: The Relationship between Early Marijuana Use and Educational Outcomes

We use unique survey data linked to nearly a decade of administrative income support data to examine the relationship between early marijuana use (at age 14 or younger) and young people's educational outcomes. We find evidence that early marijuana use is related to educational penalties that are compounded by high-intensity use and are larger for young people living in families with a history of income support receipt. The relationships between marijuana use and both high school completion and achieving a university entrance score appear to stem from selectivity into the use of marijuana. In contrast, early marijuana use is associated with significantly lower university entrance scores for those who obtain one, and we provide evidence that this effect is unlikely to be driven by selection. Collectively, these findings point to a more nuanced view of the relationship between adolescent marijuana use and educational outcomes than is suggested by the existing literature.

Is there an educational penalty for being suspended from school?

Suspension from school is a commonly used, yet controversial, school disciplinary measure. This paper uses unique survey data to estimate the impact of suspension on the educational outcomes of those suspended. It finds that while suspension is strongly associated with educational outcomes, the relationship is unlikely to be causal, but rather likely stems from differences in the characteristics of those suspended compared to those not suspended. Moreover, there is no evidence that suspension is associated with larger educational penalties for young people from disadvantaged family backgrounds compared to those from more advantaged family backgrounds. These results hold regardless of whether self-reported suspension or mother-reported suspension is considered. The absence of a clear negative causal impact of suspension on educational outcomes suggests that suspension may continue to play a role in school discipline without harming the educational prospects of those sanctioned.

Numerical prediction of the low-velocity impact damage and compression after impact strength of composite laminates

Low-velocity impact damage can drastically reduce the residual mechanical properties of the composite structure even when there is barely visible impact damage. The ability to computationally predict the extent of damage and compression after impact (CAI) strength of a composite structure can potentially lead to the exploration of a larger design space without incurring significant development time and cost penalties. A three-dimensional damage model, to predict both low-velocity impact damage and compression after impact CAI strength of composite laminates, has been developed and implemented as a user material subroutine in the commercial finite element package, ABAQUS/Explicit. The virtual tests were executed in two steps, one to capture the impact damage and the other to predict the CAI strength. The observed intra-laminar damage features, delamination damage area as well as residual strength are discussed. It is shown that the predicted results for impact damage and CAI strength correlated well with experimental testing.

Predicting low velocity impact damage and Compression-After-Impact (CAI) behaviour of composite laminates

Low-velocity impact damage can drastically reduce the residual strength of a composite structure even when the damage is barely visible. The ability to computationally predict the extent of damage and compression-after-impact (CAI) strength of a composite structure can potentially lead to the exploration of a larger design space without incurring significant time and cost penalties. A high-fidelity three-dimensional composite damage model, to predict both low-velocity impact damage and CAI strength of composite laminates, has been developed and implemented as a user material subroutine in the commercial finite element package, ABAQUS/Explicit. The intralaminar damage model component accounts for physically-based tensile and compressive failure mechanisms, of the fibres and matrix, when subjected to a three-dimensional stress state. Cohesive behaviour was employed to model the interlaminar failure between plies with a bi-linear traction–separation law for capturing damage onset and subsequent damage evolution. The virtual tests, set up in ABAQUS/Explicit, were executed in three steps, one to capture the impact damage, the second to stabilize the specimen by imposing new boundary conditions required for compression testing, and the third to predict the CAI strength. The observed intralaminar damage features, delamination damage area as well as residual strength are discussed. It is shown that the predicted results for impact damage and CAI strength correlated well with experimental testing without the need of model calibration which is often required with other damage models.

Numerical prediction of the low-velocity impact damage and compression after impact strength of composite laminates

Low-velocity impact damage can drastically reduce the residual mechanical properties of the composite structure even when there is barely visible impact damage. The ability to computationally predict the extent of damage and compression after impact (CAI) strength of a composite structure can potentially lead to the exploration of a larger design space without incurring significant development time and cost penalties. A three-dimensional damage model, to predict both low-velocity impact damage and compression after impact CAI strength of composite laminates, has been developed and implemented as a user material subroutine in the commercial finite element package, ABAQUS/Explicit. The virtual tests were executed in two steps, one to capture the impact damage and the other to predict the CAI strength. The observed intra-laminar damage features, delamination damage area as well as residual strength are discussed. It is shown that the predicted results for impact damage and CAI strength correlated well with experimental testing.

Modelling Cohesive-Frictional Particulate Solids for Bulk Handling Applications

Many powders and particulate solids are cohesive in nature and the strength often exhibits dependence on the consolidation stress. As a result, the stress history in the material leading up to a handling scenario needs to be considered when evaluating its handleability. This paper outlines the development of a DEM contact model accounting for plasticity and adhesion force, which is shown to be suitable for modelling the stress history dependent cohesive strength. The model was used to simulate the confined consolidation and the subsequent unconfined loading of iron ore fines with particle sizes up to 1.18mm. The predicted flow function was found to be comparable to the experimental results. 

Liquids with permanent porosity

Porous solids such as zeolites and metal-organic frameworks are useful in molecular separation and in catalysis, but their solid nature can impose limitations. For example, liquid solvents, rather than porous solids, are the most mature technology for post-combustion capture of carbon dioxide because liquid circulation systems are more easily retrofitted to existing plants. Solid porous adsorbents offer major benefits, such as lower energy penalties in adsorption-desorption cycles, but they are difficult to implement in conventional flow processes. Materials that combine the properties of fluidity and permanent porosity could therefore offer technological advantages, but permanent porosity is not associated with conventional liquids. Here we report free-flowing liquids whose bulk properties are determined by their permanent porosity. To achieve this, we designed cage molecules that provide a well-defined pore space and that are highly soluble in solvents whose molecules are too large to enter the pores. The concentration of unoccupied cages can thus be around 500 times greater than in other molecular solutions that contain cavities, resulting in a marked change in bulk properties, such as an eightfold increase in the solubility of methane gas. Our results provide the basis for development of a new class of functional porous materials for chemical processes, and we present a one-step, multigram scale-up route for highly soluble 'scrambled' porous cages prepared from a mixture of commercially available reagents. The unifying design principle for these materials is the avoidance of functional groups that can penetrate into the molecular cage cavities.

Regulating Digital Financial Services Agents in Developing Countries to Promote Financial Inclusion

Limited access to bank branches excludes over one billion people from accessing financial services in developing countries. Digital financial services offered by banks and mobile money providers through agents can solve this problem without the need for complex and costly physical banking infrastructures. Delivering digital financial services through agents requires a legal framework to regulate liability. This article analyses whether vicarious liability of the principal is a more efficient regulatory approach than personal liability of the agent. Agent liability in Kenya, Fiji, and Malawi is analysed to demonstrate that vicarious liability of the principal, coupled to an explicit agreement as to agent rewards and penalties, is the more efficient regulatory approach.

Proyecto de mejoramiento de procesos administrativos y operativos de Ecuadorian Cleaner Services, Cleaner Plus S.A.

ECUADORIAN CLEANER SERVICES CLEANER PLUS S.A. Es una empresa que se ha propuesto alcanzar varios objetivos en el actual Directorio conformado por Félix Marín Rueda, Presidente Ejecutivo, y Jorge Lagla Salazar, Gerente General; a pesar de que la empresa no cuenta con una Planificación estratégica como tal, sin embargo sus fines se enmarcan en planes a corto, mediano y largo plazo, los mismos que para llevarse a cabo necesitan de forma inmediata que todos los procesos de la empresa se encuentren formalizados. Uno de los principales problemas que tiene la empresa, y en el cual se sustenta la aplicación del presente proyecto, radica en la falta de un manual de procesos específicos, ya que todas las actividades actualmente se están llevando de forma empírica, lo que dificulta el actuar empresarial de Cleaner Plus S.A. evidenciando la inexistencia de planificación, organización y coordinación interna entre todas las áreas de la empresa.

Tracing coastal organic enrichment: stable isotopes and biotic indices

Neste trabalho foi efectuada uma avaliação integrada usando descritores sedimentares e biológicos ao nível da espécie e da comunidade e índices bióticos de síntese para o traçamento do enriquecimento orgânico numa região, com características dispersivas, da costa Oeste de Portugal. Na área estudada existem gradientes ambientais e biológicos relacionados com a heterogeneidade da paisagem sedimentar, a qual inclui sedimentos desde areias finas limpas a vasas. Contudo, na área próxima do emissário, esta paisagem é mais homogénea e constituída por areia fina com baixo teor em finos. Nesta região, alguns dos descritores estudados deram uma indicação coerente de alterações ambientais associadas ao enriquecimento orgânico. O potencial de oxidação - redução mostrou valores negativos até 250 m do emissário, o que indicia que a degradação da matéria orgânica que entra no sistema cria condições reduzidas no sedimento. Os isótopos estáveis de carbono e azoto no sedimento diferenciam a área mais próxima do emissário, que apresenta uma depleção de acordo com uma origem terrestre da matéria orgânica naquela parte da plataforma. Uma imagem similar foi obtida pela análise dos isótopos estáveis na macrofauna que diagnosticou a origem terrestre da matéria orgânica consumida. A composição específica e a abundância das comunidades bentónicas também são significativamente diferentes junto ao emissário, onde são dominadas por espécies oportunistas, tolerantes ao enriquecimento orgânico. No entanto, os índices bióticos em validação no âmbito da implementação da Directiva Quadro da Água, não foram eficientes a mostrar as alterações bentónicas associadas ao enriquecimento orgânico apesar de alguns índices se basearem nos limiares de tolerância/sensibilidade a este tipo de perturbação. Apesar deste caso de estudo reflectir um enriquecimento orgânico moderado, uma vez que não foram detectadas alterações sedimentares ou acumulação de matéria orgânica, nem um significativo empobrecimento das comunidades biológicas junto ao emissário, a análise ao nível dos índices bióticos de síntese pode levar à perda de informação essencial e, portanto, prejudicar a nossa capacidade de diagnóstico devendo ser usados com cuidado. A análise do conjunto de dados da composição específica forneceu uma imagem mais precisa da perturbação ambiental e descritores específicos, tais como os isótopos estáveis, permitiram uma melhor compreensão da extensão espacial do enriquecimento orgânico.

Optical processing devices and techniques for next generation optical networks

Este trabalho surge do interesse em substituir os nós de rede óptica baseados maioritariamente em electrónica por nós de rede baseados em tecnologia óptica. Espera-se que a tecnologia óptica permita maiores débitos binários na rede, maior transparência e maior eficiência através de novos paradigmas de comutação. Segundo esta visão, utilizou-se o MZI-SOA, um dispositivo semicondutor integrado hibridamente, para realizar funcionalidades de processamento óptico de sinal necessárias em nós de redes ópticas de nova geração. Nas novas redes ópticas são utilizados formatos de modulação avançados, com gestão da fase, pelo que foi estudado experimentalmente e por simulação o impacto da utilização destes formatos no desempenho do MZI-SOA na conversão de comprimento de onda e formato, em várias condições de operação. Foram derivadas regras de utilização para funcionamento óptimo. Foi também estudado o impacto da forma dos pulsos do sinal no desempenho do dispositivo. De seguida, o MZI-SOA foi utilizado para realizar funcionalidades temporais ao nível do bit e do pacote. Foi investigada a operação de um conversor de multiplexagem por divisão no comprimento de onda para multiplexagem por divisão temporal óptica, experimentalmente e por simulação, e de um compressor e descompressor de pacotes, por simulação. Para este último, foi investigada a operação com o MZI-SOA baseado em amplificadores ópticos de semicondutor com geometria de poço quântico e ponto quântico. Foi também realizado experimentalmente um ermutador de intervalos temporais que explora o MZI-SOA como conversor de comprimento de onda e usa um banco de linhas de atraso ópticas para introduzir no sinal um atraso seleccionável. Por fim, foi estudado analiticamente, experimentalmente e por simulação o impacto de diafonia em redes ópticas em diversas situações. Extendeu-se um modelo analítico de cálculo de desempenho para contemplar sinais distorcidos e afectados por diafonia. Estudou-se o caso de sinais muito filtrados e afectados por diafonia e mostrou-se que, para determinar correctamente as penalidades que ocorrem, ambos os efeitos devem ser considerados simultaneamente e não em separado. Foi estudada a escalabilidade limitada por diafonia de um comutador de intervalos temporais baseado em MZI-SOA a operar como comutador espacial. Mostrou-se também que sinais afectados fortemente por não-linearidades podem causar penalidades de diafonia mais elevadas do que sinais não afectados por não-linearidades. Neste trabalho foi demonstrado que o MZI-SOA permite construir vários e pertinentes circuitos ópticos, funcionando como bloco fundamental de construção, tendo sido o seu desempenho analisado, desde o nível de componente até ao nível de sistema. Tendo em conta as vantagens e desvantagens do MZI-SOA e os desenvolvimentos recentes de outras tecnologias, foram sugeridos tópicos de investigação com o intuito de evoluir para as redes ópticas de nova geração.

Coloquio Michel Foucault, reflexiones sobre el saber, el poder, la verdad y las prácticas de sí

En este libro se encuentran distintas posturas acerca de los dos grandes temas de Foucault: el saber y el poder. Temas que, por otra parte, marcan derroteros de búsqueda, de formulación, interrogantes que se vertieron en investigaciones que comprometen la escritura misma de las cosas. Todos los aquí presentes son estudiantes de posgrado de la carrera de filosofía, alumnos de dos seminarios que extendieron, como prácticas de formación y discusión sus trabajos en el “Coloquio Reflexiones sobre el saber, el poder, la verdad y las prácticas de sí”. Hoy, parte de estos trabajos, en los que los estudiantes arriesgaron sus propias tesis, sus pesquisas, la entrañable cualidad de quedar comprometidos con el discurso y haciendo “uso” de lo que el propio Foucault deseaba, cada uno hace de sí una parte de esa obra que es la estética de sí. En este libro queda el testimonio

Curso: Las causas profundas de la Revolución de Independencia

Indagar en las causas de larga duración como son: el nacionalismo criollo presente desde fines del siglo XVI; las cargas, impuestos y préstamos forzosos de la Corona; la explotación en un régimen puramente colonial de la minería platera; las contradicciones entre indígenas y españoles; la división racial de la sociedad; el fracaso final de la reformas borbónicas; la riqueza y el dominio educativo y cultural de la Iglesia; la difusión de las ideas ilustradas que desembocaron todas en la Revolución de Independencia y tejieron su contenido y su composición social.

Coupling anchovy eggs and hydrodynamic model as an assessement tool for estuarine ecohydrological management

Nitrate and urban waste water directives have raised the need for a better understanding of coastal systems in European Union. The incorrect application of these directives can lead to important ecological or social penalties. In the paper this problem is addressed to Ria Formosa Coastal Lagoon. Ria Formosa hosts a Natural Park, important ports of the southern Portuguese coast and significant bivalve aquaculture activity. Four major urban waste water treatment plants discharging in the lagoon are considered in this study. Its treatment level must be selected, based on detailed information from a monitoring program and on a good knowledge of the processes determining the fate of the material discharged in the lagoon. In this paper the results of a monitoring program and simulations using a coupled hydrodynamic and water quality / ecological model, MOHID, are used to characterise the system and to understand the processes in Ria Formosa. It is shown that the water residence time in most of the lagoon is quite low, of the order of days, but it can be larger in the upper parts of the channels where land generated water is discharged. The main supply of nutrients to the lagoon comes from the open sea rather than from the urban discharges. For this reason the characteristics and behaviour of the general lagoon contrasts with the behaviour of the upper reaches of the channels where the influence of the waste water treatment plants are high. In this system the bottom mineralization was found to be an important mechanism, and the inclusion of that process in the model was essential to obtain good results.

Étude de l'influence des caractéristiques des granulats sur la performance des bétons fluides à rhéologie adaptée

Les caractéristiques physiques des granulats ont une forte influence sur la performance du béton, y compris l'ouvrabilité du béton, la zone de transition, le module d'élasticité, la résistance mécanique, etc. Comparativement aux bétons conventionnels vibrés, les bétons fluides à rhéologie adapté (BFRA) beaucoup plus complexes, doivent présenter une bonne stabilité (résistance à la ségrégation), une bonne rhéologie et les résistances mécaniques souhaitées. Le choix des granulats joue un rôle majeur pour l'obtention de ces différentes propriétés. Une meilleure compréhension de l'influence des caractéristiques physiques sur la performance des BFRA est nécessaire pour leur optimisation afin d'obtenir un bon rapport performance-coût. L'objectif principal de cette étude est de comprendre l'influence des propriétés physiques des granulats (forme, densité, granulométrie, module de finesse, et la quantité de particules plates ou allongées) sur la demande en superplastifiant, la rhéologie et les propriétés mécaniques des BFRA. Les types de bétons étudiés sont les bétons autoplaçants (BAP) destinés à la construction de bâtiments, les bétons semi-autoplaçants (BSAP) destinés pour la construction et la réparation des infrastructures et les BAP destinés à la préfabrication. Quatre rapports sable/granulat total (S/G), deux sables composés (manufacturé et naturel) au laboratoire de différentes finesses (MF = 2,5 et MF = 3) et un sable naturel provenant d'usines ont été utilisés. L'influence de la compacité granulaire, du type de sable (naturel vs manufacturé) et de la teneur en fines du squelette granulaire sur les propriétés rhéologiques et mécaniques des BFRA est étudiée. Douze mélanges de BSAP ont été formulés à cet effet. L'influence du type de granulométrie (continue ou discontinue), du diamètre nominal maximal des gros granulats (10, 14 et 20 mm) et de la forme des gros granulats (roulé, aplati et allongé) sur les propriétés rhéologiques et mécaniques des BFRA ont été étudiées. Quatre types de gros granulats provenant de l'industrie et sept gros granulats reconstitués en laboratoire ont été utilisés pour prendre en compte tous ces paramètres. Les résultats montrent que la compacité granulaire est une donnée importante à prendre en compte pour la formulation d'un BFRA (BAP ou BSAP). Cette étude a également montré que les particules fines de diamètres inférieurs à 315 [micro]m sont celles qui influencent les paramètres rhéologiques des BSAP. Pour un rapport E/L constant et un diamètre d'étalement fixe, l'augmentation de la teneur de particules passant le tamis 315 [micro]m augmente la viscosité plastique, diminue le seuil de cisaillement et augmente la stabilité statique des bétons. Cette étude préconise l'utilisation des granulats concassés de granulométrie continue contenant des particules équidimensionnelles pour améliorer les propriétés rhéologiques des bétons. Enfin, grâce à cette étude, la production des BAP dans les industries connaîtra une avancée majeure par un choix stratégique des granulats. Les industries pourront notamment faire une utilisation optimale des superplastifiants, adapter la rhéologie des BAP (viscosité plastique et seuil de cisaillement) au type de BAP tout en conservant leurs caractéristiques mécaniques. Cette étude bien que scientifique, répond en d'autres termes aux besoins de l'industrie car elle propose un bon rapport performance-coût des BAP.