20,296 research outputs found

    Choice of device to view video lectures: an analysis of two independent cohorts of first-year university students

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    Video lectures and mobile learning devices have become prominent, but little is known about device choices for watching video lectures. The setting for this study, a university that provided perpetual access to personal computers and free tablet devices to all first-year students, provided a unique opportunity to study device choice in a setting where both tablets and personal computers were perpetually available. Weekly video lectures on a first-year module were made from October to April in two independent cohorts of students. YouTube analytics were used to record data on device usage for video lecture views. Tablets were initially used for almost 70% of views. However, tablet usage declined throughout the academic year, and tablets were overtaken by personal computers as the preferred device in the second half of the academic year. Findings suggest that an initial preference for using tablets to view video lectures lasts only a few months

    Dynamics of opinion formation in a small-world network

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    The dynamical process of opinion formation within a model using a local majority opinion updating rule is studied numerically in networks with the small-world geometrical property. The network is one in which shortcuts are added to randomly chosen pairs of nodes in an underlying regular lattice. The presence of a small number of shortcuts is found to shorten the time to reach a consensus significantly. The effects of having shortcuts in a lattice of fixed spatial dimension are shown to be analogous to that of increasing the spatial dimension in regular lattices. The shortening of the consensus time is shown to be related to the shortening of the mean shortest path as shortcuts are added. Results can also be translated into that of the dynamics of a spin system in a small-world network.Comment: 10 pages, 5 figure

    Identity and Search in Social Networks

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    Social networks have the surprising property of being "searchable": Ordinary people are capable of directing messages through their network of acquaintances to reach a specific but distant target person in only a few steps. We present a model that offers an explanation of social network searchability in terms of recognizable personal identities: sets of characteristics measured along a number of social dimensions. Our model defines a class of searchable networks and a method for searching them that may be applicable to many network search problems, including the location of data files in peer-to-peer networks, pages on the World Wide Web, and information in distributed databases.Comment: 4 page, 3 figures, revte

    Scale-free networks with tunable degree distribution exponents

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    We propose and study a model of scale-free growing networks that gives a degree distribution dominated by a power-law behavior with a model-dependent, hence tunable, exponent. The model represents a hybrid of the growing networks based on popularity-driven and fitness-driven preferential attachments. As the network grows, a newly added node establishes mm new links to existing nodes with a probability pp based on popularity of the existing nodes and a probability 1−p1-p based on fitness of the existing nodes. An explicit form of the degree distribution P(p,k)P(p,k) is derived within a mean field approach. For reasonably large kk, P(p,k)∌k−γ(p)F(k,p)P(p,k) \sim k^{-\gamma(p)}{\cal F}(k,p), where the function F{\cal F} is dominated by the behavior of 1/ln⁥(k/m)1/\ln(k/m) for small values of pp and becomes kk-independent as p→1p \to 1, and Îł(p)\gamma(p) is a model-dependent exponent. The degree distribution and the exponent Îł(p)\gamma(p) are found to be in good agreement with results obtained by extensive numerical simulations.Comment: 12 pages, 2 figures, submitted to PR

    Phase transitions in Ising model on a Euclidean network

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    A one dimensional network on which there are long range bonds at lattice distances l>1l>1 with the probability P(l)∝l−ήP(l) \propto l^{-\delta} has been taken under consideration. We investigate the critical behavior of the Ising model on such a network where spins interact with these extra neighbours apart from their nearest neighbours for 0≀Ύ<20 \leq \delta < 2. It is observed that there is a finite temperature phase transition in the entire range. For 0≀Ύ<10 \leq \delta < 1, finite size scaling behaviour of various quantities are consistent with mean field exponents while for 1≀Ύ≀21\leq \delta\leq 2, the exponents depend on ÎŽ\delta. The results are discussed in the context of earlier observations on the topology of the underlying network.Comment: 7 pages, revtex4, 7 figures; to appear in Physical Review E, minor changes mad

    Combustion and operating characteristics of spark-ignition engines

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    The spark-ignition engine turbulent flame propagation process was investigated. Then, using a spark-ignition engine cycle simulation and combustion model, the impact of turbocharging and heat transfer variations or engine power, efficiency, and NO sub x emissions was examined

    Watch Out for the Beast: Fear Information and Attentional Bias in Children

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    Although valenced information about novel animals changes the implicit and explicit fear beliefs of children (Field & Lawson, 2003), how it might lead to anxiety is unknown. One possibility, based on cognitive models of anxiety, is that fear information creates attentional biases similar to those seen in anxiety disorders. Children between 7 and 9 years old were given positive information about 1 novel animal, negative information about another, and no information about the 3rd. A pictorial dot-probe task was used, immediately or with a 24-hr delay, to test for attentional biases to the different animals. The results replicated the finding that fear information changes children's fear beliefs. Regardless of whether there was a delay, children acquired an attentional bias in the left visual field toward the animal about which they held negative beliefs compared to the control animal. These results imply a possible way in which fear information might contribute to acquired fear

    A network-based threshold model for the spreading of fads in society and markets

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    We investigate the behavior of a threshold model for the spreading of fads and similar phenomena in society. The model is giving the fad dynamics and is intended to be confined to an underlying network structure. We investigate the whole parameter space of the fad dynamics on three types of network models. The dynamics we discover is rich and highly dependent on the underlying network structure. For some range of the parameter space, for all types of substrate networks, there are a great variety of sizes and life-lengths of the fads -- what one see in real-world social and economical systems

    Exploring the physical activity of Iranian migrant women in the United Kingdom: a qualitative study

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    Purpose: This article explores the role migration has on the physical activity of Iranian migrant women living in the United Kingdom. Method: This qualitative study includes 22 first-generation Iranian migrant women, aged 24–64, residing in London. Data was collected through in-depth, semi-structured, individual interviews and was analyzed thematically. Results: The findings show that for those women from traditional backgrounds, migration corresponds with liberation from social and cultural pressures experienced in Iran and greater motivation to adopt a physically active lifestyle. However, for Iranian women who had arrived in the UK more recently and had a higher social standing in Iran, migration was associated with the loss of their careers, sources of income, and social networks. These issues were compounded by a lack of cohesion in Iranian migrant communities and poor access to local physical activity resources. This resulted in diminishing motivation and the subsequent de-prioritisation of the women’s physical activity, even though they had regularly engaged in physical activity in Iran. Conclusion: Despite migration leading to improving physical activity for some Iranian women, for others, migration leads to marginality in Britain. Local authorities and Iranian community organizations need to adopt innovative strategies to reach out to recent Iranian migrant women
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