Communicability across evolving networks

Many natural and technological applications generate time ordered sequences of networks, defined over a fixed set of nodes; for example time-stamped information about ‘who phoned who’ or ‘who came into contact with who’ arise naturally in studies of communication and the spread of disease. Concepts and algorithms for static networks do not immediately carry through to this dynamic setting. For example, suppose A and B interact in the morning, and then B and C interact in the afternoon. Information, or disease, may then pass from A to C, but not vice versa. This subtlety is lost if we simply summarize using the daily aggregate network given by the chain A-B-C. However, using a natural definition of a walk on an evolving network, we show that classic centrality measures from the static setting can be extended in a computationally convenient manner. In particular, communicability indices can be computed to summarize the ability of each node to broadcast and receive information. The computations involve basic operations in linear algebra, and the asymmetry caused by time’s arrow is captured naturally through the non-mutativity of matrix-matrix multiplication. Illustrative examples are given for both synthetic and real-world communication data sets. We also discuss the use of the new centrality measures for real-time monitoring and prediction.

Path planning of robots in noisy workspaces using learning automata

The problem of a manipulator operating in a noisy workspace and required to move from an initial fixed position P0 to a final position Pf is considered. However, Pf is corrupted by noise, giving rise to Pˆf, which may be obtained by sensors. The use of learning automata is proposed to tackle this problem. An automaton is placed at each joint of the manipulator which moves according to the action chosen by the automaton (forward, backward, stationary) at each instant. The simultaneous reward or penalty of the automata enables avoiding any inverse kinematics computations that would be necessary if the distance of each joint from the final position had to be calculated. Three variable-structure learning algorithms are used, i.e., the discretized linear reward-penalty (DLR-P, the linear reward-penalty (LR-P ) and a nonlinear scheme. Each algorithm is separately tested with two (forward, backward) and three forward, backward, stationary) actions.

`Tactical' living: a situated study of teenagers' negotiations around and interactions with living room media

This paper examines everyday living room interactions in which teenage household members conduct `tactical' play in order to temporarily gain access to, and disrupt, the dominant, domestic codes of living room media. The practices of individuals are interpreted, through Michel de Certeau's language of `tactics', as struggles or a series of opportunistic actions which can often reforge these codes of living, precisely because the house `rules' are not fixed or deterministic in practice. In these tactical performances of self, the use of media is enmeshed in a host of situated and symbolic action, reaffirming how media and face-to-face interactions are multiply and closely entwined in everyday living room life. This video ethnographic work examines such instances of teenagers appealing to `house' rules and demonstrating domestic helpfulness in order to gain access to media, and the tethering of media to objects through the routine practice of `markers' and `stalls'.

Wind-direction effects on urban-type flows

Practically all extant work on flows over obstacle arrays, whether laboratory experiments or numerical modelling, is for cases where the oncoming wind is normal to salient faces of the obstacles. In the field, however, this is rarely the case. Here, simulations of flows at various directions over arrays of cubes representing typical urban canopy regions are presented and discussed. The computations are of both direct numerical simulation and large-eddy simulation type. Attention is concentrated on the differences in the mean flow within the canopy region arising from the different wind directions and the consequent effects on global properties such as the total surface drag, which can change very significantly—by up to a factor of three in some circumstances. It is shown that for a given Reynolds number the typical viscous forces are generally a rather larger fraction of the pressure forces (principally the drag) for non-normal than for normal wind directions and that, dependent on the surface morphology, the average flow direction deep within the canopy can be largely independent of the oncoming wind direction. Even for regular arrays of regular obstacles, a wind direction not normal to the obstacle faces can in general generate a lateral lift force (in the direction normal to the oncoming flow). The results demonstrate this and it is shown how computations in a finite domain with the oncoming flow generated by an appropriate forcing term (e.g. a pressure gradient) then lead inevitably to an oncoming wind direction aloft that is not aligned with the forcing term vector.

Western Chess: Endgame data

This spreadsheet contains key data about that part of the endgame of Western Chess for which Endgame Tables (EGTs) have been generated by computer. It is derived from the EGT work since 1969 of Thomas Ströhlein, Ken Thompson, Christopher Wirth, Eugene Nalimov, Marc Bourzutschky, John Tamplin and Yakov Konoval. The data includes %s of wins, draws and losses (wtm and btm), the maximum and average depths of win under various metrics (DTC = Depth to Conversion, DTM = Depth to Mate, DTZ = Depth to Conversion or Pawn-push), and examples of positions of maximum depth. It is essentially about sub-7-man Chess but is updated as news comes in of 7-man EGT computations.

Communication and social regulation. the criminalization of work-related death

This paper addresses the movement towards criminalization as a tool for the regulation of work-related deaths in the United Kingdom and elsewhere in the last 20 years. This can be seen as reflecting dissatisfaction with the relevant law, although it is best understood in symbolic terms as a response to a disjunction between the instrumental nature and communicative aspirations of regulatory law. This paper uses empirical data gathered from interviews with members of the public to explore the role that such an offence might play. The findings demonstrate that the failures of regulatory law give rise to a desire for criminalization as a means of framing work-related safety events in normative terms.

Pianos for the people: the manufacture, marketing and sale of pianos as consumer durables, 1850-1914

During the second half of the nineteenth century, British society experienced a rise in real incomes and a change in its composition, with the expansion of the middle classes. These two factors led to a consumer revolution, with a growing, but still segmented, demand for household goods that could express status and aspiration. At the same time technological changes and new ways of marketing and selling goods made these goods more affordable. This paper analyzes these themes and the process of mediation that took place between producers, retailers, and consumers, by looking at the most culturally symbolic of nineteenth century consumer goods, the piano.

The civic zeitgeist: nationalism and liberal values in the European radical right

This article examines the relationship between nationalism and liberal values, and more specifically the redefinition of boundaries between national communities and others in the rhetoric of radical right parties in Europe. The aim is to examine the tension between radical right party discourse and the increasing need to shape this discourse in liberal terms. We argue that the radical right parties that successfully operate within the democratic system tend to be those best able to tailor their discourse to the liberal and civic characteristics of national identity so as to present themselves and their ideologies as the true authentic defenders of the nation's unique reputation for democracy, diversity and tolerance. Comparing the success of a number of European radical right parties ranging from the most electorally successful SVP to the more mixed BNP, FN and NPD, we show that the parties that effectively deploy the symbolic resources of national identity through a predominantly voluntaristic prism tend to be the ones that fare better within their respective political systems. In doing so, we challenge the conventional view in the study of nationalism which expects civic values to shield countries from radicalism and extremism.

Thessaly and Macedon at Delphi

The Daochos Monument at Delphi has received some scholarly attention from an art-historical and archaeological perspective; this article, however, examines it rather as a reflection of contemporary Thessalian history and discourse, an aspect which has been almost entirely neglected. Through its visual imagery and its inscriptions, the monument adopts and adapts long-standing Thessalian themes of governance and identity, and achieves a delicate balance with Macedonian concerns to forge a symbolic rapprochement between powers and cultures in the Greek north. Its dedicator, Daochos, emerges as far more than just the puppet of Philip II of Macedon. This hostile and largely Demosthenic characterisation, which remains influential even in modern historiography, is far from adequate in allowing for an understanding of the relationship between Thessalian and Macedonian motivations at this time, or of the importance of Delphi as the pan-Hellenic setting of their interaction. Looking closely at the Daochos Monument instead allows for a rare glimpse into the Thessalian perspective in all its complexity.

The maximum rate of mammal evolution

How fast can a mammal evolve from the size of a mouse to the size of an elephant? Achieving such a large transformation calls for major biological reorganization. Thus, the speed at which this occurs has important implications for extensive faunal changes, including adaptive radiations and recovery from mass extinctions. To quantify the pace of large-scale evolution we developed a metric, clade maximum rate, which represents the maximum evolutionary rate of a trait within a clade. We applied this metric to body mass evolution in mammals over the last 70 million years, during which multiple large evolutionary transitions occurred in oceans and on continents and islands. Our computations suggest that it took a minimum of 1.6, 5.1, and 10 million generations for terrestrial mammal mass to increase 100-, and 1,000-, and 5,000- fold, respectively. Values for whales were down to half the length (i.e., 1.1, 3, and 5 million generations), perhaps due to the reduced mechanical constraints of living in an aquatic environment. When differences in generation time are considered, we find an exponential increase in maximum mammal body mass during the 35 million years following the Cretaceous–Paleogene (K–Pg) extinction event. Our results also indicate a basic asymmetry in macroevolution: very large decreases (such as extreme insular dwarfism) can happen at more than 10 times the rate of increases. Our findings allow more rigorous comparisons of microevolutionary and macroevolutionary patterns and processes. Keywords: haldanes, biological time, scaling, pedomorphosis

Rights, the environment and Part V of the Criminal Justice and Public Order Act 1994

Using figures derived from the UK Home Office, this paper analyses and reviews the impact and deployment of Part V of the Criminal Justice and Public Order Act 1994 since its enactment. This is done with special reference to its impact on citizenship and the regulation of ‘the environment’ and associated rural spaces. It is argued that, notwithstanding the actual use of the public order clauses in Part V of the Act, its underlying meanings are largely of a symbolic nature. Such symbolism is, however, a powerful indication of the defence of particularist constructions of rural space. It can also open out new conditions of possibility, providing a useful ‘oppressed’ status and media spectacle for a range of protesters and activists.

The unsteady flow of a weakly compressible fluid in a thin porous layer II: three-dimensional theory

We consider the problem of determining the pressure and velocity fields for a weakly compressible fluid flowing in a three-dimensional layer, composed of an inhomogeneous, anisotropic porous medium, with vertical side walls and variable upper and lower boundaries, in the presence of vertical wells injecting and/or extracting fluid. Numerical solution of this three-dimensional evolution problem may be expensive, particularly in the case that the depth scale of the layer h is small compared to the horizontal length scale l, a situation which occurs frequently in the application to oil and gas reservoir recovery and which leads to significant stiffness in the numerical problem. Under the assumption that $\epsilon\propto h/l\ll 1$, we show that, to leading order in $\epsilon$, the pressure field varies only in the horizontal directions away from the wells (the outer region). We construct asymptotic expansions in $\epsilon$ in both the inner (near the wells) and outer regions and use the asymptotic matching principle to derive expressions for all significant process quantities. The only computations required are for the solution of non-stiff linear, elliptic, two-dimensional boundary-value, and eigenvalue problems. This approach, via the method of matched asymptotic expansions, takes advantage of the small aspect ratio of the layer, $\epsilon$, at precisely the stage where full numerical computations become stiff, and also reveals the detailed structure of the dynamics of the flow, both in the neighbourhood of wells and away from wells.

Britain and the Commonwealth: confronting the past - imagining the future

This is an extended version of Philip Murphy's inaugural lecture as director of the Institute of Commonwealth Studies, delivered on 23 February 2011. It traces the relationship of the UK with the wider Commonwealth over 40 years, paying particular attention to the rhetoric of governments and opposition parties from Wilson and Heath to Cameron. It examines the reasons for the Commonwealth being relegated to a peripheral role in British foreign policy, especially European preoccupations and the issues of Rhodesia and South Africa. It argues that the Commonwealth remains of considerable practical and enormous symbolic importance to the UK. The British government should engage with the Commonwealth more than it has done in the recent past and the Commonwealth should be both open to and critical of its imperial past.

An experiment in the Assimilation of Data in Dynamical Analysis

A system for continuous data assimilation is presented and discussed. To simulate the dynamical development a channel version of a balanced barotropic model is used and geopotential (height) data are assimilated into the models computations as data become available. In the first experiment the updating is performed every 24th, 12th and 6th hours with a given network. The stations are distributed at random in 4 groups in order to simulate 4 areas with different density of stations. Optimum interpolation is performed for the difference between the forecast and the valid observations. The RMS-error of the analyses is reduced in time, and the error being smaller the more frequent the updating is performed. The updating every 6th hour yields an error in the analysis less than the RMS-error of the observation. In a second experiment the updating is performed by data from a moving satellite with a side-scan capability of about 15°. If the satellite data are analysed at every time step before they are introduced into the system the error of the analysis is reduced to a value below the RMS-error of the observation already after 24 hours and yields as a whole a better result than updating from a fixed network. If the satellite data are introduced without any modification the error of the analysis is reduced much slower and it takes about 4 days to reach a comparable result to the one where the data have been analysed.