873 research outputs found

    Anomaly detection in temporal graph data: An iterative tensor decomposition and masking approach

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    Sensors and Internet-of-Things scenarios promise a wealth of interaction data that can be naturally represented by means of timevarying graphs. This brings forth new challenges for the identification and removal of temporal graph anomalies that entail complex correlations of topological features and activity patterns. Here we present an anomaly detection approach for temporal graph data based on an iterative tensor decomposition and masking procedure. We test this approach using highresolution social network data from wearable sensors and show that it successfully detects anomalies due to sensor wearing time protocols.published_or_final_versio

    Distinct trajectories of leisure time physical activity and predictors of trajectory class membership: a 22 year cohort study

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    <p>Abstract</p> <p>Background</p> <p>Prospective studies linking social factors to long term patterns of physical activity are lacking. In this 22 year longitudinal study, we seek to identify long term patterns of involvement in leisure time physical activity (LTPA), and explore socioeconomic and demographic predictors of distinct LTPA trajectories.</p> <p>Methods</p> <p>Among 2102 individuals aged 18–60 years in 1981 who participated in the 1981 Canada Fitness Survey/1988 Campbell's Survey of Well-Being, 1186 (56.4%) completed questionnaires for the 2002/04 follow-up. Complete data on LTPA at all 3 surveys were available for 884 participants. Latent class growth analysis was used to identify major classes of LTPA trajectories; predictors of class membership were identified using polytomous logistic regression.</p> <p>Results</p> <p>Four latent classes were identified: <it>inactive</it>, <it>increasers</it>, <it>active</it>, and <it>decreasers </it>(53%, 26%, 12%, and 9% of participants, respectively). Women, older participants, those with lower household income, and with lower educational attainment, were significantly less likely to follow <it>active </it>(Vs. <it>inactive</it>) trajectories of LTPA. Disadvantaged groups with respect to education and income were also significantly more likely to follow <it>decreasing </it>(Vs. <it>active</it>) trajectories.</p> <p>Conclusion</p> <p>There is a need for continued efforts to increase overall population levels of LTPA, particularly among socially disadvantaged groups with respect to income and education, who are most likely to experience unfavorable trajectories of LTPA.</p

    ParticipACTION: A mass media campaign targeting parents of inactive children; knowledge, saliency, and trialing behaviours

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    <p>Abstract</p> <p>Background</p> <p>In late 2007, Canada's ParticipACTION national physical activity mass media campaign was re-launched, with an initial campaign targeting parents of elementary school-aged children. The campaign informed them about the risks of physical inactivity for children and youth. The purpose of this study was to assess campaign awareness and understanding following the campaign, and to identify whether exposure to this campaign was likely associated with behaviour change.</p> <p>Methods</p> <p>A convenience sample of 1,500 adults was recruited though an existing panel (n = 60,000) of Canadian adults to participate in online surveys. Initial campaign exposure included "prompted" and "unprompted" recall of specific physical activity messages from the 2007 ParticipACTION campaign, knowledge of the benefits of PA, saliency, and initial trial behaviours to help their children become more active.</p> <p>Results</p> <p>One quarter of respondents showed unprompted recall of specific message content from the ParticipACTION campaign, and prompted recall was 57%. Message recall and understanding was associated with knowledge about physical activity, and that in turn was related to high saliency. Saliency was associated with each of the physical activity-related trial behaviours asked.</p> <p>Conclusion</p> <p>Campaign awareness and understanding was high following this ParticipACTION campaign, and was associated with intermediate campaign outcomes, including saliency and trial behaviours. This is relevant to campaign evaluations, as it suggests that an initial focus on influencing awareness and understanding is likely to lead to more substantial change in campaign endpoints.</p

    Addressing the socioeconomic divide in computational modeling for infectious diseases.

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    Gender gaps in urban mobility

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    Abstract Mobile phone data have been extensively used to study urban mobility. However, studies based on gender-disaggregated large-scale data are still lacking, limiting our understanding of gendered aspects of urban mobility and our ability to design policies for gender equality. Here we study urban mobility from a gendered perspective, combining commercial and open datasets for the city of Santiago, Chile. We analyze call detail records for a large cohort of anonymized mobile phone users and reveal a gender gap in mobility: women visit fewer unique locations than men, and distribute their time less equally among such locations. Mapping this mobility gap over administrative divisions, we observe that a wider gap is associated with lower income and lack of public and private transportation options. Our results uncover a complex interplay between gendered mobility patterns, socio-economic factors and urban affordances, calling for further research and providing insights for policymakers and urban planners

    Dynamics of Transformation from Segregation to Mixed Wealth Cities

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    We model the dynamics of the Schelling model for agents described simply by a continuously distributed variable - wealth. Agents move to neighborhoods where their wealth is not lesser than that of some proportion of their neighbors, the threshold level. As in the case of the classic Schelling model where segregation obtains between two races, we find here that wealth-based segregation occurs and persists. However, introducing uncertainty into the decision to move - that is, with some probability, if agents are allowed to move even though the threshold level condition is contravened - we find that even for small proportions of such disallowed moves, the dynamics no longer yield segregation but instead sharply transition into a persistent mixed wealth distribution. We investigate the nature of this sharp transformation between segregated and mixed states, and find that it is because of a non-linear relationship between allowed moves and disallowed moves. For small increases in disallowed moves, there is a rapid corresponding increase in allowed moves, but this tapers off as the fraction of disallowed moves increase further and finally settles at a stable value, remaining invariant to any further increase in disallowed moves. It is the overall effect of the dynamics in the initial region (with small numbers of disallowed moves) that shifts the system away from a state of segregation rapidly to a mixed wealth state. The contravention of the tolerance condition could be interpreted as public policy interventions like minimal levels of social housing or housing benefit transfers to poorer households. Our finding therefore suggests that it might require only very limited levels of such public intervention - just sufficient to enable a small fraction of disallowed moves, because the dynamics generated by such moves could spur the transformation from a segregated to mixed equilibrium.Comment: 12 pages, 7 figure

    Physiology as a tool for at-risk animal recovery planning: An analysis of Canadian recovery strategies with global recommendations

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    Many government organizations use recovery planning to synthesize threats, propose management strategies, and determine recovery criteria for threatened wildlife. Little is known about the extent to which physiological knowledge has been used in recovery planning, despite its potential to offer key biological information that could aid in recovery success. Using recovery strategies for at-risk animal species in Canada as a case study, we analyzed the prevalence, purpose, and type of physiological knowledge being used in recovery planning. We found that 73% of strategies contained mention of physiology and that incorporation of physiology has increased since 2006. Of the various types of physiological tools available, reference to stress, immune, thermal, and bioenergetic metrics appeared most frequently. Physiological information was more likely to be found in the background and threat assessment sections compared to action and future research sections, and less likely to be included in strategies for arthropods and birds compared to other taxonomic groups. By synthesizing our results with previous studies, we provide recommendations to encourage the application of physiological tools in recovery planning worldwide, such as increased incorporation of physiology in ongoing threat monitoring, critical habitat assessments, monitoring the success of recovery actions, and modeling responses to future environmental changes.publishedVersio
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