Visoelastic relaxation of Venusian coronae and mountain belts: Constraints on global heat flow and tectonism

Venus differs from Earth in that water is essentially absent and its surface temperatures are about 470 K higher. The competing effects of high surface temperature and dry lithologies on the long-term history of surface topography have been studied using the finite-element method. The relaxation history of surface topographic features, such as coronae and mountain belts, is a function of thermal gradient, crustal thickness and lithology, regional stresses, and basal tractions applied to the lithosphere. In this study, we have examined the relative effects of these factors over a period of 500 Ma (presumed to be the mean age of the venusian surface)

Application of velocity-based gain-scheduling to lateral auto-pilot design for an agile missile

In this paper a modern gain-scheduling methodology is proposed which exploits recently developed velocity-based techniques to resolve many of the deficiencies of classical gain-scheduling approaches (restriction to near equilibrium operation, to slow rate of variation). This is achieved while maintaining continuity with linear methods and providing an open design framework (any linear synthesis approach may be used) which supports divide and conquer design strategies. The application of velocity-based gain-scheduling techniques is demonstrated in application to a demanding, highly nonlinear, missile control design task. Scheduling on instantaneous incidence (a rapidly varying quantity) is well-known to lead to considerable difficulties with classical gain-scheduling methods. It is shown that the methods proposed here can, however, be used to successfully design an effective and robust gain-scheduled controller

Response of mouse epidermal cells to single doses of heavy-particles

The survival of mouse epidermal cells to heavy-particles has been studied In Vivo by the Withers clone technique. Experiments with accelerated helium, lithium and carbon ions were performed. The survival curve for the helium ion irradiations used a modified Bragg curve method with a maximum tissue penetration of 465 microns, and indicated that the dose needed to reduce the original cell number to 1 surviving cell/square centimeters was 1525 rads with a D sub o of 95 rads. The LET at the basal cell layer was 28.6 keV per micron. Preliminary experiments with lithium and carbon used treatment doses of 1250 rads with LET's at the surface of the skin of 56 and 193 keV per micron respectively. Penetration depths in skin were 350 and 530 microns for the carbon and lithium ions whose Bragg curves were unmodified. Results indicate a maximum RBE for skin of about 2 using the skin cloning technique. An attempt has been made to relate the epidermal cell survival curve to mortality of the whole animal for helium ions

Non-minimally coupled multi-scalar black holes

We study the static, spherically symmetric black hole solutions for a non-minimally coupled multi-scalar theory. We find numerical solutions for values of the scalar fields when a certain constraint on the maximal charge is satisfied. Beyond this constraint no black hole solutions exist. This constraint therefore corresponds to extremal solutions, however, this does not match the \kappa = 0 constraint which typically indicates extremal solutions in other models. This implies that the set of extremal solutions have non-zero, finite and varying surface gravity. These solutions also violate the no-hair theorems for N>1 scalar fields and have previously been proven to be linearly stable.Comment: 6 pages, 4 figure

Book Design: A Study in Communicating Information Within the Field of Music

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Fast, responsive decentralized graph coloring

Graph coloring problem arises in numerous networking applications. We solve it in a fully decentralized way (ı.e., with no message passing). We propose a novel algorithm that is automatically responsive to topology changes, and we prove that it converges to a proper coloring in O(NlogN) time with high probability for generic graphs, when the number of available colors is greater than Δ , the maximum degree of the graph, and in O(logN) time if Δ=O(1) . We believe the proof techniques used in this paper are of independent interest and provide new insight into the properties required to ensure fast convergence of decentralized algorithms

Updating Neighbour Cell List via Crowdsourced User Reports: A Framework for Measuring Time Performance

In modern wireless networks deployments, each serving node needs to keep its Neighbour Cell List (NCL) constantly up to date to keep track of network changes. The time needed by each serving node to update its NCL is an important parameter of the network’s reliability and performance. An adequate estimate of such parameter enables a significant improvement of self-configuration functionalities. This paper focuses on the update time of NCLs when an approach of crowdsourced user reports is adopted. In this setting, each user periodically reports to the serving node information about the set of nodes sensed by the user itself. We show that, by mapping the local topological structure of the network onto states of increasing knowledge, a crisp mathematical framework can be obtained, which allows in turn for the use of a variety of user mobility models. Further, using a simplified mobility model we show how to obtain useful upper bounds on the expected time for a serving node to gain Full Knowledge of its local neighbourhood

BLC: Private Matrix Factorization Recommenders via Automatic Group Learning

We propose a privacy-enhanced matrix factorization recommender that exploits the fact that users can often be grouped together by interest. This allows a form of “hiding in the crowd” privacy. We introduce a novel matrix factorization approach suited to making recommendations in a shared group (or “nym”) setting and the BLC algorithm for carrying out this matrix factorization in a privacy-enhanced manner. We demonstrate that the increased privacy does not come at the cost of reduced recommendation accuracy

Schools and their communities: pupil and teacher perceptions of community action

In England over the last two decades, there has been a growing interest in the role of English schools in developing, facilitating and supporting young people’s community participation. A number of policy initiatives have sought to build the capacity and opportunities for youth participation. Research suggests, however, that pupils and schools are often prohibited by significant barriers from becoming involved with community activities, particularly those which might occur beyond the school environment itself. In March 2010 the UK Labour government launched a Youth Community Action initiative for England, piloted across five local authorities, which aimed to involve young people of 14-16 years-of-age in community action. Following the UK general election in May 2010, the Conservative-Liberal Democrat coalition government terminated these pilots but was quick to announce the launch and piloting of a National Citizen Service for 16-19 year olds in England. Purpose Drawing on research conducted with participants in one Youth Community Action pilot project, the aim of this study was to explore the perceptions and understandings of young people regarding their involvement in community action activities and how this compared to the perceptions and understandings of the teachers responsible for co-ordinating such activities. Sample In the final synthesis, the sample comprised 614 pupil questionnaires, representing a response rate of 24 percent of the pupils in the 9 participating schools. 11 semi-structured interviews and one focus group interview were conducted with pupils in 6 of the schools, with a further 8 semi-structured interviews conducted with teachers in these 6 schools. Design and methods A questionnaire was administered to pupils participating in the Youth Community Action pilot, enabling an exploration of self-reported behavioural attitudes and perceptions. The data collected was analysed thematically, with an identification of common themes in responses. In addition, factor analysis and a series of Chi² tests of association were carried out. The use of semi-structured interviews, the data from which were analysed thematically, enabled a qualitative exploration of pupils’ and teachers’ self-reported perceptions of community action activities. Results The findings of our questionnaires report that those pupils who know more about their local neighbourhood and community are likely to report greater levels of concern for what happens within it. This suggests that pupils’ learning about their neighbourhoods and community is likely to be beneficial toward developing affective attachments to them. For the pupils in our data-set, simply possessing pro-social behaviours and attitudes was not a sufficient or necessary condition for their community awareness and involvement. It suggests that, at least for a notable number of pupils, active engagement in the community requires cultivation and learning beyond pro-social behaviours. The semi-structured interviews report that pupils identify the school as the key source of information about community engagement opportunities, but also indicate that there is a marked difference in the activities which teachers identify their pupils as having undertaken, and the ability of pupils to vocalise these themselves. A further notable finding was a focus on the practical (time, distance, age-constraints) and social (peer-pressure) barriers to community action activities to the exclusion of specifically educational (lack of understanding and skills) barriers. Conclusions Results from this study suggest that schools represent an important source for pupils’ community involvement, but that in our sample pupils often lack the vocabulary with which to explain the extent and nature of such engagement. Pupils and teachers identify a range of barriers to and benefits of community involvement, but these do not include a lack of understanding or skills. The research raises important questions in the context of recent policy trends in England