On Resilient Behaviors in Computational Systems and Environments

The present article introduces a reference framework for discussing resilience of computational systems. Rather than a property that may or may not be exhibited by a system, resilience is interpreted here as the emerging result of a dynamic process. Said process represents the dynamic interplay between the behaviors exercised by a system and those of the environment it is set to operate in. As a result of this interpretation, coherent definitions of several aspects of resilience can be derived and proposed, including elasticity, change tolerance, and antifragility. Definitions are also provided for measures of the risk of unresilience as well as for the optimal match of a given resilient design with respect to the current environmental conditions. Finally, a resilience strategy based on our model is exemplified through a simple scenario.Comment: The final publication is available at Springer via http://dx.doi.org/10.1007/s40860-015-0002-6 The paper considerably extends the results of two conference papers that are available at http://ow.ly/KWfkj and http://ow.ly/KWfgO. Text and formalism in those papers has been used or adapted in the herewith submitted pape

A method for exploratory repeated-measures analysis applied to a breast-cancer screening study

When a model may be fitted separately to each individual statistical unit, inspection of the point estimates may help the statistician to understand between-individual variability and to identify possible relationships. However, some information will be lost in such an approach because estimation uncertainty is disregarded. We present a comparative method for exploratory repeated-measures analysis to complement the point estimates that was motivated by and is demonstrated by analysis of data from the CADET II breast-cancer screening study. The approach helped to flag up some unusual reader behavior, to assess differences in performance, and to identify potential random-effects models for further analysis.Comment: Published in at http://dx.doi.org/10.1214/11-AOAS481 the Annals of Applied Statistics (http://www.imstat.org/aoas/) by the Institute of Mathematical Statistics (http://www.imstat.org

The effect of variable labels on deep learning models trained to predict breast density

Purpose: High breast density is associated with reduced efficacy of mammographic screening and increased risk of developing breast cancer. Accurate and reliable automated density estimates can be used for direct risk prediction and passing density related information to further predictive models. Expert reader assessments of density show a strong relationship to cancer risk but also inter-reader variation. The effect of label variability on model performance is important when considering how to utilise automated methods for both research and clinical purposes. Methods: We utilise subsets of images with density labels to train a deep transfer learning model which is used to assess how label variability affects the mapping from representation to prediction. We then create two end-to-end deep learning models which allow us to investigate the effect of label variability on the model representation formed. Results: We show that the trained mappings from representations to labels are altered considerably by the variability of reader scores. Training on labels with distribution variation removed causes the Spearman rank correlation coefficients to rise from $0.751\pm0.002$ to either $0.815\pm0.006$ when averaging across readers or $0.844\pm0.002$ when averaging across images. However, when we train different models to investigate the representation effect we see little difference, with Spearman rank correlation coefficients of $0.846\pm0.006$ and $0.850\pm0.006$ showing no statistically significant difference in the quality of the model representation with regard to density prediction. Conclusions: We show that the mapping between representation and mammographic density prediction is significantly affected by label variability. However, the effect of the label variability on the model representation is limited

A mode-matching analysis of dielectric-filled resonant cavities coupled to terahertz parallelplate waveguides

We use the mode-matching technique to study parallel-plate waveguide resonant cavities that are filled with a dielectric. We apply the generalized scattering matrix theory to calculate the power transmission through the waveguide-cavities. We compare the analytical results to experimental data to confirm the validity of this approach

East Asia and the global/transatlantic/Western crisis

This paper introduces the special collection on East Asia and the Global Crisis. After justifying why a focus on East Asia is appropriate, it draws out the main themes that run through the individual contributions. These are the extent to which the region is decoupling from the global economy (or the West), the increasing legitimacy of statist alternatives to neoliberal development strategies, and the impact of crises on the definition of ―region‖ and the functioning of regional institutions and governance mechanisms

Energy-dependent tunneling from few-electron dynamic quantum dots

We measure the electron escape rate from surface-acoustic-wave dynamic quantum dots (QDs) through a tunnel barrier. Rate equations are used to extract the tunneling rates, which change by an order of magnitude with tunnel-barrier-gate voltage. We find that the tunneling rates depend on the number of electrons in each dynamic QD because of Coulomb energy. By comparing this dependence to a saddle-point-potential model, the addition energies of the second and third electron in each dynamic QD are estimated. The scale (similar to a few meV) is comparable to those in static QDs as expected

The Metal-Insulator Transition in \u3cem\u3eVO\u3csub\u3e2\u3c/sub\u3e\u3c/em\u3e Studied using Terahertz Apertureless Near-Field Microscopy

We have studied the metal-insulator transition in a vanadium dioxide (VO2) thin film using terahertz apertureless near-field optical microscopy. We observe a variation of the terahertz amplitude due to the phase transition induced by an applied voltage across the sample. The change of the terahertz signal is related to the abrupt change of the conductivity of the VO2 film at the metal-insulator transition. The subwavelength spatial resolution of this near-field microscopy makes it possible to detect signatures of micron-scale metallic domains in inhomogeneous VO2 thin films

Mapping the global potential exposure of soaring birds to terrestrial wind energy expansion

The wind energy sector is steadily growing, and the number of wind turbines is expected to expand across large areas of the globe in the near future. While the development of wind energy can contribute to mitigating climate change, it also poses challenges to wildlife, particularly birds, due to increased collision risk with wind turbines. Here we quantify and map potential conflicts between the potential for wind energy development and the distribution of terrestrial soaring birds. We explore the relationship between species traits (including body mass, migration ecology and extinction risk) and exposure to potential wind energy development, and identified areas of potential conflict between wind power production and soaring bird conservation. We considered the full range of each species, as well as separately analyzing the breeding, non-breeding and passage ranges for migratory species. We show that exposure to potential wind energy development is similar for soaring and non-soaring bird species. Within different parts of the range of soaring bird species, passage distributions have significantly higher potential for wind energy development than the full, breeding or non-breeding ranges. Moreover, exposure to potential wind energy development was higher within the ranges of heavier soaring bird species and those that are migratory. We show that areas of conflict between soaring bird conservation and potential wind energy development could be very large, particularly when the passage ranges of soaring bird species are considered. Such areas of potential conflict are largely unprotected. This highlights a risk for soaring birds from potential wind energy development wherever it is not carefully sited in order to minimise environmental impacts.Peer reviewe