959 research outputs found

    The effect of pre-processing and grain structure on the bio-corrosion and fatigue resistance of magnesium alloy AZ31

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    Magnesium alloys are broadly used for structural applications in the aerospace and automotive industries as well as in consumer electronics. While a high specific strength is the forte of magnesium alloys, one serious limitation for Mg alloys is their corrosion performance. Unlike aluminium, it does not form a stable passive film to provide long-term protection from further corrosion. The poor corrosion resistance of magnesium and magnesium alloys is regarded as a major drawback, and significant effort has been focused on improving this.[1-3] However, the high reactivity of magnesium alloys in corrosive media can be used to advantage in biomedical applications, particularly in temporary implants where the capacity of a material for bio-degradation is one of the most sought after properties. Indeed, permanent implant materials, such as stainless steel, titanium alloys or Nitinol (55Ni-45Ti), are the only choices currently available for hard tissue implantation. They can cause permanent physical irritation, long-term endothelial dysfunction and chronic inflammatory local reaction. Sometimes a second operation is needed for the implant to be removed. Given the ability of the human body to gradually recover and regenerate damaged tissue, the ideal solution would thus be a degradable implant, which would offer a physiologically less invasive repair and temporary support during tissue recovery. After fulfilling its function, this implant would be obliterated, being absorbed by the body. This philosophy of implant surgery would also be of particular interest for endovascular stent

    Molecular dynamics study of solvation effects on acid dissociation in aprotic media

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    Acid ionization in aprotic media is studied using Molecular Dynamics techniques. In particular, models for HCl ionization in acetonitrile and dimethylsulfoxide are investigated. The proton is treated quantum mechanically using Feynman path integral methods and the remaining molecules are treated classically. Quantum effects are shown to be essential for the proper treatment of the ionization. The potential of mean force is computed as a function of the ion pair separation and the local solvent structure is examined. The computed dissociation constants in both solvents differ by several orders of magnitude which are in reasonable agreement with experimental results. Solvent separated ion pairs are found to exist in dimethylsulfoxide but not in acetonitrile. Dissociation mechanisms in small clusters are also investigated. Solvent separated ion pairs persist even in aggregates composed of rather few molecules, for instance, as few as thirty molecules. For smaller clusters or for large ion pair separations cluster finite-size effects come into play in a significant fashion.Comment: Plain LaTeX. To appear in JCP(March 15). Mpeg simulations available at http://www.chem.utoronto.ca/staff/REK/Videos/clusters/clusters.htm

    Caregiver Perceptions of Autism and Neurodevelopmental Disabilities in New Delhi, India

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    Evidence suggests that parenting an autistic child or a child with neurodevelopmental disabilities can be more challenging than parenting a child meeting their developmental milestones, especially when there is a dearth of support services, such as in low- and middle-income countries (LMICs). Despite the majority of the world’s children residing in LMICs, there are limited studies examining the understanding of developmental disorders and autism in these regions. We therefore aim to investigate perceptions of autism and developmental disabilities in caregivers of children in an urban setting in New Delhi, India. Thirteen semi-structured interviews with parents/caregivers of children were conducted in three groups: (1) caregivers with a child with a diagnosis of autism spectrum disorder (ASD); (2) caregivers with a child with a diagnosis of intellectual disability (ID); (3) and caregivers with children meeting their developmental milestones. Transcripts were analysed using framework analysis. Three themes on the impact of cultural and contextual factors on the recognition, interpretation, and reporting of autistic symptoms are discussed, and additional themes focus on the impact of diagnosis and family support. Our findings highlighted a vital need for greater community awareness and recognition of autism in India, for example through community and healthcare training, which may help to reduce stigma and facilitate wider family support

    Information Horizons in Networks

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    We investigate and quantify the interplay between topology and ability to send specific signals in complex networks. We find that in a majority of investigated real-world networks the ability to communicate is favored by the network topology on small distances, but disfavored at larger distances. We further discuss how the ability to locate specific nodes can be improved if information associated to the overall traffic in the network is available.Comment: Submitted top PR

    Unemployment and the Demand for Unions

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    Why do people join open-shop unions when they would receive union wage rates even if they were not members? Why are unionization rates so low in the south-east of England? To address these questions, which we treat as interrelated, the paper considers the idea that unions offer insurance against victimization and arbitrary dismissal. Consistent with our theoretical approach, we find that union density is greatest, ceteris paribus, within establishments in areas of high unemployment.

    Diagnostic Assessment of Autism in Children Using Telehealth in a Global Context: a Systematic Review

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    Reflecting the significant delays in autism assessments globally, studies have explored whether autism assessments conducted via telehealth are feasible and accurate. This systematic review investigated the psychometric properties of autism assessment tools for children administered via telehealth and examined the diagnostic accuracy of telehealth assessment procedures compared to care-as-usual in-person assessments. Relevant databases (MEDLINE, Embase and PsycInfo) were searched for eligible studies (PROSPERO: CRD42022332500). In total, 18 studies were included, collectively assessing 1593 children for autism. Telehealth assessments for autism were largely comparable to in-person assessments, with a diagnostic agreement of 80–88.2%. Individual behavioral observation tools, diagnostic interviews, and clinician-administered screening tools demonstrated acceptable validity. For many children, diagnostic decision-making can be expedited without loss of validity using telehealth

    Internet Predictions

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    More than a dozen leading experts give their opinions on where the Internet is headed and where it will be in the next decade in terms of technology, policy, and applications. They cover topics ranging from the Internet of Things to climate change to the digital storage of the future. A summary of the articles is available in the Web extras section
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