982 resultados para science experiments
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Natural convection heat transfer from a heat generating horizontal cylinder enclosed in a square cavity, where a temperature difference exists across its vertical walls has been experimentally investigated for the range 2×104
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The initial composition of acrylic bone cement along with the mixing and delivery technique used can influence its final properties and therefore its clinical success in vivo. The polymerisation of acrylic bone cement is complex with a number of processes happening simultaneously. Acrylic bone cement mixing and delivery systems have undergone several design changes in their advancement, although the cement constituents themselves have remained unchanged since they were first used. This study was conducted to determine the factors that had the greatest effect on the final properties of acrylic bone cement using a pre-filled bone cement mixing and delivery system. A design of experiments (DoE) approach was used to determine the impact of the factors associated with this mixing and delivery method on the final properties of the cement produced. The DoE illustrated that all factors present within this study had a significant impact on the final properties of the cement. An optimum cement composition was hypothesised and tested. This optimum recipe produced cement with final mechanical and thermal properties within the clinical guidelines and stated by ISO 5833 (International Standard Organisation (ISO), International standard 5833: implants for surgery—acrylic resin cements, 2002), however the low setting times observed would not be clinically viable and could result in complications during the surgical technique. As a result further development would be required to improve the setting time of the cement in order for it to be deemed suitable for use in total joint replacement surgery.
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Time domain astronomy has come of age with astronomers now able to monitor the sky at high cadence both across the electromagnetic spectrum and using neutrinos and gravitational waves. The advent of new observing facilities permits new science, but the ever increasing throughput of facilities demands efficient communication of coincident detections and better subsequent coordination among the scientific community so as to turn detections into scientific discoveries. To discuss the revolution occurring in our ability to monitor the Universe and the challenges it brings, on 2012 April 25-26 a group of scientists from observational and theoretical teams studying transients met with representatives of the major international transient observing facilities at the Kavli Royal Society International Centre, UK. This immediately followed the Royal Society Discussion meeting "New windows on transients across the Universe" held in London. Here we present a summary of the Kavli meeting at which the participants discussed the science goals common to the transient astronomy community and analysed how to better meet the challenges ahead as ever more powerful observational facilities come on stream.
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Tese de doutoramento, Farmácia (Química Farmacêutica e Terapêutica), Universidade de Lisboa, Faculdade de Farmácia, 2015
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Researchers want to run scientific experiments focusing on their disciplines. They do not want to know how and where the experiments are executed. Science gateways hide details by coordinating the execution of experiments using different infrastructures and workflow systems. ER-flow/SHIWA and SCI-BUS project developed repositories to share artefacts such as applications, portlets, workflows, etc. inside and among research communities. Sharing artefacts in re-positories enable gateway developers to reuse them when building a new gateway and/or creating a new application.
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In this work we solve Mathematical Programs with Complementarity Constraints using the hyperbolic smoothing strategy. Under this approach, the complementarity condition is relaxed through the use of the hyperbolic smoothing function, involving a positive parameter that can be decreased to zero. An iterative algorithm is implemented in MATLAB language and a set of AMPL problems from MacMPEC database were tested.
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Herodotus' logos represents many examples ofthe relationship between political and paradigmatic authority, and the synthesis ofthese examples in a community characterized by free and equal speech. Herodotus' walkabout narrator sets forth an inquiry into knowledge-seeking he extends the isegoria principle from Athenian politics to the broader world. The History demonstrates (a) various modes of constructing meaning, (b) interacting notions ofhow people have lived and living questions as to how we ought to live, and (c) an investigation ofthe nature and limits ofhuman knowledge. Representing diverse wisdom, publicly and privately discovered and presented, Herodotus sets forth Solon's wise advice and law-making, the capital punishment of the learned Anacharsis, the investigative outrages of Cambyses and Psammetichus' more pious experiments. Their stories challenge and complement their communities' characters - the relative constraint under which the Egyptians and Persians make their investigations, the Scythians' qualified openness and the relative fearlessness and freedom in which the Greeks set forth their inquiries. Setting forth the investigator-storykeeper as a poetic historian, Herodotus shows that history as poetry thwarts natural decay by allowing custom to be reformed in an open milieu, and thus win through and survive. Despite the potential dangers that openness shares with tyranny, Herodotus' inquiry sets up a contest ofworld-views in which it is mutability that openness affords a community that ensures its survival.
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A simple and inexpensive linear magnetic field sweep generating system suitable for magnetic resonance experiments is described. The circuit, utilising a modified IC bootstrap configuration, generates field sweep over a wide range of sweep durations with excellent sweep linearity.
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Recopilación de experimentos químicos recogidos a lo largo de veinte años de experiencia docente con alumnos de entre once y dieciocho años en el Reino Unido, cuya eficacia ha sido probada y, por tanto, pueden ser utilizados en los laboratorios de las escuelas. Los experimentos se agrupan por capítulos, cada experimento tiene, en primer lugar, una lista de los aparatos necesarios, seguida de información sobre seguridad y las instrucciones paso a paso sobre cómo llevarlo a cabo y, al final, los resultados obtenidos en la prueba.
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Guía que explica cómo configurar y utilizar un laboratorio de química en casa con instrucciones, paso a paso, para la realización de experimentos en química básica. La primera parte de la publicación se dedica a describir lo esencial que se necesita para equipar, aprender a trabajar de forma segura y dominar las habilidades de un laboratorio. El resto del libro está compuesto por diecisiete capítulos que incluyen, la mayoría de ellos, varias sesiones de laboratorio cada una dedicada a un tema en particular. Las sesiones son adecuadas para un nivel medio o de primer año de curso de laboratorio de química.
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Cincuenta experimentos que ilustran los principios básicos de la percepción visual: distorsiones de longitud y tamaño; inclinaciones, giros, etc. Muchos de los experimentos comienzan con un truco óptico que se ha visto previamente. Luego, utilizando materiales simples, se tendrá la oportunidad de experimentar con esta ilusión.
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Con materiales de uso corriente, los niños pueden realizar más de cuarenta juegos y experimentos sencillos que les ayudaran a comprender mejor qué es el tiempo y cómo se mide. Las actividades son fáciles de realizar y están dirigidas a niños, a partir de diez años, que ya han alcanzado un nivel aceptable de lectura comprensiva. Estos experimentos no entrañan ningún peligro y no requieren el uso de sustancias ni materiales especiales.