947 research outputs found

    Is organic diet really necessary for children?

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    The presentation focuse on the impact of pesticides on growing organisms, such as infants and young childre

    ELASTICITY of SHORT FIBRE REINFORCED POLYAMIDE: MORPHOLOGICAL AND NUMERICAl ANALYSIS OF FIBRE ORIENTATION EFFECTS

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    The fatigue behaviour of injection moulded short fibre reinforced polymers depends upon fibre orientation, as shown in experiments conducted with notched specimens injected through different injection gates. The different fatigue behaviour is mainly related to the different local elastic properties, as determined by the different fibre orientation patterns, resulting into different strain distributions. In order to quantify the relationship between fibre orientation and elastic constants, the Cell Method was applied to volumes extracted from the specimens, reconstructed by micro-tomography

    Exploring Locally to Grow Globally: A Community Excursion-based Elective for Intensive English Programs

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    The community excursion-based elective course (CE) has been designed for the Intensive English Program (IEP) at the International Language Institute (ILI) in Northampton, Massachusetts. The class provides access and information to international adult learners who are interested in learning more about the local community and culture for academic, professional and personal purposes. CE students will be exposed to various businesses, organizations, institutions and services in the community while being fully supported by a qualified teacher. The types of excursions identified in this Capstone project differ in several ways from the extra-curricular activities and cultural exchanges that are commonly offered by most IEPs. First of all, these excursions are designed to focus on the everyday routines and practices of each hosting site. Secondly, students will participate in site tours and have discussions with each hosting community representative with the purpose of developing intercultural competency and language acquisition. Finally, students will spend a third of the elective reflecting upon their authentic experiences for the purpose of gaining a deeper understanding of their host community

    How do we decide what to do? Resting-state connectivity patterns and components of self-generated thought linked to the development of more concrete personal goals

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    Human cognition is not limited to the available environmental input but can consider realities that are different to the here and now. We describe the cognitive states and neural processes linked to the refinement of descriptions of personal goals. When personal goals became concrete, participants reported greater thoughts about the self and the future during mind-wandering. This pattern was not observed for descriptions of TV programmes. Connectivity analysis of participants who underwent a resting-state functional magnetic resonance imaging scan revealed neural traits associated with this pattern. Strong hippocampal connectivity with ventromedial pre-frontal cortex was common to better-specified descriptions of goals and TV programmes, while connectivity between hippocampus and the pre-supplementary motor area was associated with individuals whose goals were initially abstract but became more concrete over the course of the experiment. We conclude that self-generated cognition that arises during the mind-wandering state can allow goals to be refined, and this depends on neural systems anchored in the hippocampus

    ANALYSIS OF CRACK PROPAGATION DURING FATIGUE TESTS IN INJECTION MOULDED NOTCHED SPECIMENS MADE OF SHORT GLASS FIBRE REINFORCED POLYAMIDE

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    In this work, we present the results of fatigue tests on injection moulded, notched specimens made of short glass fibre reinforced polyamide 66, containing 50%w of fibres. Specimens have three different notch radii (2 mm, 1 mm and 0.5 mm). The local fibre orientation was assessed by analysing the fibre orientation distribution using the optical method. Crack nucleation and propagation was monitored during fatigue tests by microscope observations in back light conditions. This technique allowed for observing and measuring the crack length. The role of propagation was quantified and discussed, by comparison with data previously obtained using a lower amount of reinforcing fibres and PA 6 matrix. It appears that with a higher content of fibres, most of the fatigue test is spent in nucleating the cracks, while propagation takes places over the last few cycles. In previous tests, with 30% glass fibres and PA6 matrix, crack propagation was dominant (more than 50% of total fatigue life), particularly for a small notch root radius

    Studio del danneggiamento mediante tomografia in luce del sincrotrone: impatto di un cono d’ombra sulla qualità finale delle ricostruzioni

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    Un’accurata osservazione della geometria tridimensionale di cricche e difetti è necessaria per lostudio dei meccanismi alla base del processo di danneggiamento. I metodi convenzionali utilizzati a questoscopo sono distruttivi o non possiedono una sufficiente risoluzione. Le tecniche di imaging che utilizzano laluce di sincrotrone, ed in particolare la microtomografia (micro-CT) a raggi X, invece, uniscono i vantaggi di unatecnica non distruttiva ad un’elevata risoluzione spaziale e risultano quindi particolarmente interessanti. Unlimite all’applicazione di questa tecnica è costituito dalla propensione della cricca a richiudersi una volta rimossoil carico che ha provocato il danneggiamento, superabile attraverso l’impiego di un dispositivo in grado diesercitare un carico di trazione durante l’acquisizione dei dati. Facendo riferimento al set-up sperimentale dellalinea SYRMEP di Elettra, il sincrotrone di Trieste, e tralasciando per il momento i vincoli legati a pesi eingombri, è possibile pensare di inserire tra camera di ionizzazione e CCD una macchina per prove di trazionemono-colonna commerciale, in grado di mantenere aperto il difetto per tutta la durata della tomografia. Inquesto lavoro viene valutato l’impatto di questo vincolo sulla qualità finale delle ricostruzioni

    Monitoring Crack Tip Position in Adhesively Bonded Joints Under Mixed I+II Mode Loading

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    The use of adhesive joints has gained favour in recent years, due to their capacity for weight reduction, improved stress distribution, and enhanced fatigue resistance. However, the widespread use of adhesive joints in structural applications is hindered, because reliable and mature inspection and defect detection techniques are not yet available. Adhesive joints in structural applications are subject to fatigue loading, during which debonds can initiate and propagate, ultimately leading to potential failure. In the majority of cases, joints operate under mixed-mode loading conditions. In this work, a steel Cracked Lap Shear specimen was tested to investigate the crack growth behaviour of adhesive joints under mixed I+II mode loading. To address the challenge of monitoring these joints, a range of experimental techniques was employed. These techniques included Visual testing, Digital Image Correlation, and Optical Backscatter Reflectometry. The different methods were evaluated and compared to determine their effectiveness in locating the crack tip within joints during fatigue propagation
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