The nature and structure of the white-reflecting underside ‘scales’ on the hind wing of Pseudolestes mirabilis (Odonata: Pseudolestidae)

This is the final version of the article. Available from the publisher via the DOI in this record.The Hainanese endemic damselfly, Pseudolestes mirabilis, is unique among the Odonata in having brilliant silvery-white reflective areas on the underside of the hind wings in mature males. The light reflected is easily seen to be several times brighter than that from normal white pruinescence. The hind wing upsides have a striking coppery appearance due to the filtering of light reflected from the inside of the reflective area through bright amber tinted wing membranes, colour which results from small amounts of melanin in those parts of the membrane. Visual signals are thus produced from both sides of the wing and may be used to advertise territory occupancy while perched, as well as having an obvious semiotic function in aerial agonistic displays between pairs of males. The structure consists of a deep layer of long, parallel, flat wax fibres, secreted from the faces of cross-veins in individual wing cells over the affected areas. This is a spectacular and novel mode of cuticular wax secretion. The structure adds about 23–27% to the mass of the hind wing, which may explain its unusual shape and shortness. However this character is also present in females, which lack the wax fibres, hence it may be an unusual example of an epigametic male trait being partially expressed in females.P. Vukusic and M.R. Nixon acknowledge the financial support of AFOSR grant FA9550-10-1-0020

Dislocation Free Island Formation in Heteroepitaxial Growth: An Equilibrium Study

We investigate the equilibrium properties of strained heteroepitaxial systems, incorporating the formation and the growth of a wetting film, dislocation free island formation, and ripening. The derived phase diagram provides a detailed characterization of the possible growth modes in terms of the island density, equilibrium island size, and wetting layer thickness. Comparing our predictions with experimental results we discuss the growth conditions that can lead to stable islands as well as ripening.Comment: 4 pages, LaTeX, 3 ps figure

Extreme TeV blazars and the intergalactic magnetic field

We study the four BL Lac objects (RGB J0152+017, 1ES 0229+200, 1ES 0347-121 and PKS 0548-322) detected in the TeV band but not present in the 1FGL catalogue of the Fermi/Large Area Telescope. We analize the 24 months of LAT data deriving gamma-ray fluxes or upper limits that we use to assemble their spectral energy distributions (SED). We model the SEDs with a standard one-zone leptonic model, also including the contribution of the reprocessed radiation in the multi GeV band, emitted by the pairs produced through the conversion of the primary TeV emission by interaction with the cosmic optical-IR background. For simplicity, in the calculation of this component we adopt an analytical approach including some simplifying assumptions, in particular i) the blazar high energy emission is considered on average stable over times of the order of 10^7 years and ii) the observer is exactly on-axis. We compare the physical parameters derived by the emission model with those of other high-energy emitting BL Lacs, confirming that TeV BL Lacs with a rather small GeV flux are characterized by extremely low values of the magnetic field and large values of the electron energies. The comparison between the flux in the GeV band and that expected from the reprocessed TeV emission allows us to confirm and strengthen the lower limit of B >10^{-15} G for the intergalactic magnetic field using a theoretically motivated spectrum for the primary high-energy photons.Comment: 11 pages, 7 figures, accepted for publication in M.N.R.A.

Null Models of Economic Networks: The Case of the World Trade Web

In all empirical-network studies, the observed properties of economic networks are informative only if compared with a well-defined null model that can quantitatively predict the behavior of such properties in constrained graphs. However, predictions of the available null-model methods can be derived analytically only under assumptions (e.g., sparseness of the network) that are unrealistic for most economic networks like the World Trade Web (WTW). In this paper we study the evolution of the WTW using a recently-proposed family of null network models. The method allows to analytically obtain the expected value of any network statistic across the ensemble of networks that preserve on average some local properties, and are otherwise fully random. We compare expected and observed properties of the WTW in the period 1950-2000, when either the expected number of trade partners or total country trade is kept fixed and equal to observed quantities. We show that, in the binary WTW, node-degree sequences are sufficient to explain higher-order network properties such as disassortativity and clustering-degree correlation, especially in the last part of the sample. Conversely, in the weighted WTW, the observed sequence of total country imports and exports are not sufficient to predict higher-order patterns of the WTW. We discuss some important implications of these findings for international-trade models.Comment: 39 pages, 46 figures, 2 table

Subgraphs in random networks

Understanding the subgraph distribution in random networks is important for modelling complex systems. In classic Erdos networks, which exhibit a Poissonian degree distribution, the number of appearances of a subgraph G with n nodes and g edges scales with network size as \mean{G} ~ N^{n-g}. However, many natural networks have a non-Poissonian degree distribution. Here we present approximate equations for the average number of subgraphs in an ensemble of random sparse directed networks, characterized by an arbitrary degree sequence. We find new scaling rules for the commonly occurring case of directed scale-free networks, in which the outgoing degree distribution scales as P(k) ~ k^{-\gamma}. Considering the power exponent of the degree distribution, \gamma, as a control parameter, we show that random networks exhibit transitions between three regimes. In each regime the subgraph number of appearances follows a different scaling law, \mean{G} ~ N^{\alpha}, where \alpha=n-g+s-1 for \gamma<2, \alpha=n-g+s+1-\gamma for 2<\gamma<\gamma_c, and \alpha=n-g for \gamma>\gamma_c, s is the maximal outdegree in the subgraph, and \gamma_c=s+1. We find that certain subgraphs appear much more frequently than in Erdos networks. These results are in very good agreement with numerical simulations. This has implications for detecting network motifs, subgraphs that occur in natural networks significantly more than in their randomized counterparts.Comment: 8 pages, 5 figure

Remote physiological monitoring: Clinical, financial, and behavioral outcomes in a heart failure population

This article reports on the outcomes associated with remote physiological monitoring (RPM) conducted as part of a heart failure disease management program. Claims data, medical records, data transmission records, and survey results for 91 individuals ages 50–92 (mean 74 years) successfully completing a heart failure RPM program were analyzed for time periods before, during, and after the monitoring intervention. The program was associated with significant reductions in per member per month costs and emergency room and hospital utilization. More detailed analyses were performed for specific gender and age subgroups. Participant surveys indicated high levels of satisfaction, and improvements in self-perceived health status, self-efficacy, and self-management behaviors. This study is the first to assess the impact of a RPM program following removal of the monitoring equipment. The results indicate that RPM, as a component of a traditional disease management program, has a sustained, beneficial effect on participants’ lifestyles after the monitoring period has ended

Representational predicaments at three Hong Kong sites

Representational predicaments arise when a job incumbent believes that attributions and images assumed by dominant authorities unfavourably ignore, or disproportionately and unfavourably emphasize, aspects of the incumbent\u27s own work and social identity. This is likely to happen when the incumbent does not have a close relationship with a dominant authority, and when power asymmetries give the former relatively little control over which aspects of their work and social identity are made visible or invisible to the latter. We draw on critical incident interviews from three organizations to illustrate a typology of six types of representational predicament: invasive spotlighting, idiosyncratic spotlighting, embedded background work, paradoxical social visibility, standardization of work processes, and standardization of work outputs. We analyse responses to representational predicaments according to whether they entailed exit, voice, loyalty, or neglect. Incumbents tended to respond with loyalty if they felt able and willing to accommodate their work behaviour and/or social identity to the dominant representations, and if there were sufficient compensatory factors, such as intrinsic rewards from the work or solidarity with colleagues. Exit or neglect appeared to reflect the belief that it was impossible to accommodate. Power asymmetries appeared to deter voice. Individual employees with a close and cordial working relationship with a member of a dominant authority group, or who were relationally networked to one, appeared not to experience representational predicaments

The pairwise disconnectivity index as a new metric for the topological analysis of regulatory networks

<p>Abstract</p> <p>Background</p> <p>Currently, there is a gap between purely theoretical studies of the topology of large bioregulatory networks and the practical traditions and interests of experimentalists. While the theoretical approaches emphasize the global characterization of regulatory systems, the practical approaches focus on the role of distinct molecules and genes in regulation. To bridge the gap between these opposite approaches, one needs to combine 'general' with 'particular' properties and translate abstract topological features of large systems into testable functional characteristics of individual components. Here, we propose a new topological parameter – the pairwise disconnectivity index of a network's element – that is capable of such bridging.</p> <p>Results</p> <p>The pairwise disconnectivity index quantifies how crucial an individual element is for sustaining the communication ability between connected pairs of vertices in a network that is displayed as a directed graph. Such an element might be a vertex (i.e., molecules, genes), an edge (i.e., reactions, interactions), as well as a group of vertices and/or edges. The index can be viewed as a measure of topological redundancy of regulatory paths which connect different parts of a given network and as a measure of sensitivity (robustness) of this network to the presence (absence) of each individual element. Accordingly, we introduce the notion of a path-degree of a vertex in terms of its corresponding incoming, outgoing and mediated paths, respectively. The pairwise disconnectivity index has been applied to the analysis of several regulatory networks from various organisms. The importance of an individual vertex or edge for the coherence of the network is determined by the particular position of the given element in the whole network.</p> <p>Conclusion</p> <p>Our approach enables to evaluate the effect of removing each element (i.e., vertex, edge, or their combinations) from a network. The greatest potential value of this approach is its ability to systematically analyze the role of every element, as well as groups of elements, in a regulatory network.</p