1,528 research outputs found

    General Opinion Formation Games with Social Group Membership (Short Paper)

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    Modeling how agents form their opinions is of paramount importance for designing marketing and electoral campaigns. In this work, we present a new framework for opinion formation which generalizes the well-known Friedkin-Johnsen model by incorporating three important features: (i) social group membership, that limits the amount of influence that people not belonging to the same group may lead on a given agent; (ii) both attraction among friends, and repulsion among enemies; (iii) different strengths of influence lead from different people on a given agent, even if the social relationships among them are the same. We show that, despite its generality, our model always admits a pure Nash equilibrium which, under opportune mild conditions, is even unique. Next, we analyze the performances of these equilibria with respect to a social objective function defined as a convex combination, parametrized by a value λ ∈ [0, 1], of the costs yielded by the untruthfulness of the declared opinions and the total cost of social pressure. We prove bounds on both the price of anarchy and the price of stability which show that, for not-too-extreme values of λ, performance at equilibrium are very close to optimal ones. For instance, in several interesting scenarios, the prices of anarchy and stability are both equal to (Equation presented) which never exceeds 2 for λ ∈ [1/5, 1/2]

    On Augmented Stochastic Submodular Optimization: Adaptivity, Multi-Rounds, Budgeted, and Robustness

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    In this work we consider the problem of Stochastic Submodular Maximization, in which we would like to maximize the value of a monotone and submodular objective function, subject to the fact that the values of this function depend on the realization of stochastic events. This problem has applications in several areas, and in particular it well models basic problems such as influence maximization and stochastic probing. In this work, we advocate the necessity to extend the study of this problem in order to include several different features such as a budget constraint on the number of observations, the chance of adaptively choosing what we observe or the presence of multiple rounds. We here speculate on the possible directions that this line of research can take. In particular, we will discuss about interesting open problems mainly in the settings of robust optimization and online learning

    Nash Social Welfare in Selfish and Online Load Balancing (Short Paper)

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    In load balancing problems there is a set of clients, each wishing to select a resource from a set of permissible ones, in order to execute a certain task. Each resource has a latency function, which depends on its workload, and a client's cost is the completion time of her chosen resource. Two fundamental variants of load balancing problems are selfish load balancing (aka. load balancing games), where clients are non-cooperative selfish players aimed at minimizing their own cost solely, and online load balancing, where clients appear online and have to be irrevocably assigned to a resource without any knowledge about future requests. We revisit both problems under the objective of minimizing the Nash Social Welfare, i.e., the geometric mean of the clients' costs. To the best of our knowledge, despite being a celebrated welfare estimator in many social contexts, the Nash Social Welfare has not been considered so far as a benchmarking quality measure in load balancing problems. We provide tight bounds on the price of anarchy of pure Nash equilibria and on the competitive ratio of the greedy algorithm under very general latency functions, including polynomial ones. For this particular class, we also prove that the greedy strategy is optimal, as it matches the performance of any possible online algorithm

    Early childhood educator training: The value of educating educators on movement, play and physical literacy development - A three country case study.

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    A child's early movement and active play experiences influence their attitudes towards physical activity throughout their childhood and into adulthood (Blair, 1992). Yet, it has been suggested that early childhood educators (ECEs) may not recognize the importance of, or give enough attention to, movement skills and physical development opportunities for young children (Clark, 2014; Whitehead, 2010). The education, or lack thereof, that ECEs receive could be an important factor. International comparisons of overall ECE preparation and training have demonstrated that some countries' ECEs are more highly educated than others (Howells and Sääkslahti, 2019). Using a case study approach, this paper conducts an analysis and comparison of three countries to examine the value and role of physical activity/movement education for ECEs to enable them to support physical literacy development in early childhood educational settings. In addition, lessons learned from creating such educational opportunities in the context of their various locations (Manitoba in Canada, Kent in England, and Escambia County, FL in U.S.A.) are discussed. A purposeful sample was used as these countries have relatively low levels of educational requirements for ECEs, yet children start attending early years’ education from the earliest life points (Howells & Sääkslahti, 2019)

    Role of potassium channels in the antinociception induced by agonists of alpha2-adrenoceptors

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    1. The effect of the administration of pertussis toxin (PTX) as well as modulators of different subtypes of K(+) channels on the antinociception induced by clonidine and guanabenz was evaluated in the mouse hot plate test. 2. Pretreatment with pertussis toxin (0.25 μg per mouse i.c.v.) 7 days before the hot-plate test, prevented the antinociception induced by both clonidine (0.08–0.2 mg kg(−1), s.c.) and guanabenz (0.1–0.5 mg kg(−1), s.c.). 3. The administration of the K(ATP) channel openers minoxidil (10 μg per mouse, i.c.v.), pinacidil (25 μg per mouse, i.c.v.) and diazoxide (100 mg kg(−1), p.o.) potentiated the antinociception produced by clonidine and guanabenz whereas the K(ATP) channel blocker gliquidone (6 μg per mouse, i.c.v.) prevented the α(2) adrenoceptor agonist-induced analgesia. 4. Pretreatment with an antisense oligonucleotide (aODN) to mKv1.1, a voltage-gated K(+) channel, at the dose of 2.0 nmol per single i.c.v. injection, prevented the antinociception induced by both clonidine and guanabenz in comparison with degenerate oligonucleotide (dODN)-treated mice. 5. The administration of the Ca(2+)-gated K(+) channel blocker apamin (0.5–2.0 ng per mouse, i.c.v.) never modified clonidine and guanabenz analgesia. 6. At the highest effective doses, none of the drugs used modified animals' gross behaviour nor impaired motor coordination, as revealed by the rota-rod test. 7. The present data demonstrate that both K(ATP) and mKv1.1 K(+) channels represent an important step in the transduction mechanism underlying central antinociception induced by activation of α(2) adrenoceptors

    Dandy-Walker malformation: is the "tail sign" the key sign?

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    OBJECTIVE.To demonstrate the value of the "tail sign" in the assessment of Dandy-Walker Malformation (DWM). METHODS: A total of 31fetal MRI, performed before 24 weeks of gestation after second-line US examination between May 2013 and September 2014, were examined retrospectively. All MRI examinations were performed using a 1.5 Tesla magnet without maternal sedation. RESULTS: MRI diagnosed 15/31 cases of Dandy-Walker Malformation, 6/31 cases of vermian partial caudal agenesis, 2/31 of vermian hypoplasia, 4/31 of vermian malrotation, 2/31 of Walker-Warburg Syndrome, 1/31 of Blake pouch cyst, 1/31 of rhombencephalosynapsis. All data were compared with fetopsy results, Fetal MR after the 30th week or postnatal MRI; the follow up depended on the maternal decision to terminate or continue pregnancy. In our review study we found the presence of the "tail sign"; this sign was visible only in Dandy-Walker Malformation and Walker-Warburg Syndrome. CONCLUSION: The "tail sign" could be helpful in the difficult differential diagnosis between Dandy Walker, vermian malrotation, vermian hypoplasia and vermian partial agenesis

    Publishing artificial intelligence research papers: A tale of three journals

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    With the growth in Artificial Intelligence in Medicine (AIM) research and the plethora of informatics journals, there is some confusion where to direct an AIM-related manuscript for peer review and possible pub- lication. As editors for three Elsevier biomedical informatics journals that publish AI-related papers, plus the publisher who oversees all three of these journals, we are aware of such confusion and felt it would be helpful to provide some guidance to prospective authors. Accordingly, we present this joint editorial that is being published in all three of our journals. Although there is some overlap among the types of papers that we publish, we offer here some advice on how best to select a preferred publication venue for your medical AI research papers

    Publishing Artificial Intelligence Research Papers: A Tale of Three Journals

    Get PDF
    With the growth in Artificial Intelligence in Medicine (AIM) research and the plethora of informatics journals, there is some confusion where to direct an AIM-related manuscript for peer review and possible publication. As editors for three Elsevier biomedical informatics journals that publish AI-related papers, plus the publisher who oversees all three of these journals, we are aware of such confusion and felt it would be helpful to provide some guidance to prospective authors. Accordingly, we present this joint editorial that is being published in all three of our journals. Although there is some overlap among the types of papers that we publish, we offer here some advice on how best to select a preferred publication venue for your medical AI research papers

    MOBILE MAPPING FOR CULTURAL HERITAGE: THE SURVEY OF THE COMPLEX OF ST. JOHN OF THE HERMITS IN PALERMO (ITALY)

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    During the 11th and 12th century, the Arab-Norman architectural style characterized the most beautiful and important Cultural Heritage buildings in Sicily, and especially in Palermo (Italy). The relevance of these monuments is highlighted by their inclusion in the UNESCO World Heritage Sites List in 2015. For many years, the University of Palermo has been studying and documenting several Arab-Norman cultural assets, and in particular, the complex of St. John of the Hermits in Palermo (Italy). A first detailed 3D survey of the main structures of this complex was carried out using a terrestrial laser scanner while the 3D survey of the entire complex was made using a Mobile Mapping System (MMS). The paper describes the workflow and the results of the mobile mapping survey undertaken with a Handheld Mobile Laser Scanner (HMLS) based on Simultaneous Localisation and Mapping (SLAM) technologies. The work allowed surveying the entire site with an extremely fast acquisition and obtaining the geometric information useful for historical architectural valuations. In addition, due to the characteristics of the site, the work enabled the assessment of the HMLS data processing testing different automatic algorithms for point cloud filtering

    Is spark plasma sintering suitable for the densification of continuous carbon fibre - UHTCMCs?

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    For the first time we show that spark plasma sintering can efficiently replace hot pressing for the densification of UHTCMCs, in the present case ZrB2/SiC composites reinforced with continuous carbon fibres. To this purpose, the same materials were first produced by hot pressing as baseline samples and then by spark plasma sintering (SPS) to compare microstructure and basic mechanical properties. A special emphasis was given to the study of interfaces, in case of both coated and uncoated carbon fibres. SPS allowed for faster sintering but required an adjustment of the temperature to avoid fibre degradation compared to hot pressing. With similar porosity levels, we observed a slight decrease of flexural strength (300 vs 470 MPa), and an improvement of fracture toughness (15 vs 10 MPa√m) for SPSed samples. SPS was proved to be an effective method for the consolidation of continuous fibre reinforced UHTC composites
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