An economic analysis of ransomware and its welfare consequences

We present in this work an economic analysis of ransomware, a relatively new form of cyber-enabled extortion. We look at how the illegal gains of the criminals will depend on the strategies they use, examining uniform pricing and price discrimination. We also explore the welfare costs to society of such strategies. In addition, we present the results of a pilot survey which demonstrate proof of concept in evaluating the costs of ransomware attacks. We discuss at each stage whether the different strategies we analyse have been encountered already in existing malware, and the likelihood of them being implemented in the future. We hope this work will provide some useful insights for predicting how ransomware may evolve in the future

Three-frequency resonances in dynamical systems

We investigate numerically and experimentally dynamical systems having three interacting frequencies: a discrete mapping (a circle map), an exactly solvable model (a system of coupled ordinary differential equations), and an experimental device (an electronic oscillator). We compare the hierarchies of three-frequency resonances we find in each of these systems. All three show similar qualitative behaviour, suggesting the existence of generic features in the parameter-space organization of three-frequency resonances.Comment: See home page http://lec.ugr.es/~julya

Not throwing out the baby with the bathwater: Bell's condition of local causality mathematically 'sharp and clean'

The starting point of the present paper is Bell's notion of local causality and his own sharpening of it so as to provide for mathematical formalisation. Starting with Norsen's (2007, 2009) analysis of this formalisation, it is subjected to a critique that reveals two crucial aspects that have so far not been properly taken into account. These are (i) the correct understanding of the notions of sufficiency, completeness and redundancy involved; and (ii) the fact that the apparatus settings and measurement outcomes have very different theoretical roles in the candidate theories under study. Both aspects are not adequately incorporated in the standard formalisation, and we will therefore do so. The upshot of our analysis is a more detailed, sharp and clean mathematical expression of the condition of local causality. A preliminary analysis of the repercussions of our proposal shows that it is able to locate exactly where and how the notions of locality and causality are involved in formalising Bell's condition of local causality.Comment: 14 pages. To be published in PSE volume "Explanation, Prediction, and Confirmation", edited by Dieks, et a

Evidence-Based Policy: Where Is Our Theory of Evidence?

This article critically analyses the concept of evidence in evidence‐based policy, arguing that there is a key problem: there is no existing practicable theory of evidence, one which is philosophically‐grounded and yet applicable for evidence‐based policy. The article critically considers both philosophical accounts of evidence and practical treatments of evidence in evidence‐based policy. It argues that both fail in different ways to provide a theory of evidence that is adequate for evidence‐based policy. The article contributes to the debate about how evidence can and should be used to reduce contingency in science and in policy based on science

Noise and Inertia-Induced Inhomogeneity in the Distribution of Small Particles in Fluid Flows

The dynamics of small spherical neutrally buoyant particulate impurities immersed in a two-dimensional fluid flow are known to lead to particle accumulation in the regions of the flow in which rotation dominates over shear, provided that the Stokes number of the particles is sufficiently small. If the flow is viewed as a Hamiltonian dynamical system, it can be seen that the accumulations occur in the nonchaotic parts of the phase space: the Kolmogorov--Arnold--Moser tori. This has suggested a generalization of these dynamics to Hamiltonian maps, dubbed a bailout embedding. In this paper we use a bailout embedding of the standard map to mimic the dynamics of impurities subject not only to drag but also to fluctuating forces modelled as white noise. We find that the generation of inhomogeneities associated with the separation of particle from fluid trajectories is enhanced by the presence of noise, so that they appear in much broader ranges of the Stokes number than those allowing spontaneous separation

Global Diffusion in a Realistic Three-Dimensional Time-Dependent Nonturbulent Fluid Flow

We introduce and study the first model of an experimentally realizable three-dimensional time-dependent nonturbulent fluid flow to display the phenomenon of global diffusion of passive-scalar particles at arbitrarily small values of the nonintegrable perturbation. This type of chaotic advection, termed {\it resonance-induced diffusion\/}, is generic for a large class of flows.Comment: 4 pages, uuencoded compressed postscript file, to appear in Phys. Rev. Lett. Also available on the WWW from http://formentor.uib.es/~julyan/, or on paper by reques

The Regolith of 4 Vesta - Inferences from Howardites

Asteroid 4 Vesta is quite likely the parent asteroid of the howardite, eucrite and diogenite meteorites - the HED clan. Eucrites and diogenites are the products of igneous processes; the former are basaltic composition rocks from flows, and shallow and deep intrusive bodies, whilst the latter are cumulate orthopyroxenites thought to have formed deep in the crust. Impact processes have excavated these materials and mixed them into a suite of polymict breccias. Howardites are polymict breccias composed mostly of clasts and mineral fragments of eucritic and diogenitic parentage, with neither end-member comprising more than 90% of the rock. Early work interpreted howardites as representing the lithified regolith of their parent asteroid. Recently, howardites have been divided into two subtypes; fragmental howardites, being a type of non-regolithic polymict breccia, and regolithic howardites, being lithified remnants of the active regolith of 4 Vesta. We are in the thralls of a collaborative investigation of the record of impact mixing contained within howardites, which includes studies of their mineralogy, petrology, bulk rock compositions, and bulk rock and clast noble gas contents. One goal of our investigation is to test the hypothesis that some howardites represent breccias formed from an ancient, well-mixed regolith on Vesta. Another is to use our results to further understand regolith processing on differentiated asteroids as compared to what has been learned from the Moon. We have made petrographic observations and electron microprobe analyses on 21 howardites and 3 polymict eucrites. We have done bulk rock analyses using X-ray fluorescence spectrometry and are completing inductively coupled plasma mass spectrometry analyses. Here, we discuss our petrologic and bulk compositional results in the context of regolith formation. Companion presentations describe the noble gas results and compositional studies of low-Ca pyroxene clasts

Can self-report questionnaires create illness cognitions in middle-aged men?

Objective: To examine the effect of questionnaire context on self-reported illness cognition. Design: A single-item measure of the perceived impact of lower urinary tract symptoms (LUTS) was embedded twice in a questionnaire battery completed by community-dwelling middle-aged males (N = 1,790). The impact measure was placed in two distinct questionnaire contexts; at the end of a general somatic symptoms questionnaire, and following an illness-specific symptoms questionnaire. The order of the two questionnaire contexts was counter-balanced in a random sub-sample. Main Outcome Measures: An established single-item measure of the perceived impact of LUTS. Results: Concordance between the two single-item measures was moderate. Scores on a single-item measure of impact were significantly lower when assessed immediately following the completion of a LUTS-specific questionnaire than when assessed following the completion of a general symptoms questionnaire. There was no evidence of order effects. The observed effect was moderated by the severity of LUTS such that the difference in perceived impact scores between contexts (where general symptoms context > illness-specific context) increased as urinary symptoms increased. Conclusion: Questionnaire context systematically influenced responses on self-report measures of illness impact. The magnitude of the context effect was largest in the highest quintile of LUTS severity, a difference of >0.5 on a scale with a range of 3. These findings may have implications for situations where patient reported outcome measures are used to evaluate healthcare interventions or inform treatment decisions

Are NH3_3 and CO2_2 ice present on Miranda?

Published near-infrared spectra of the four largest classical Uranian satellites display the presence of discrete deposits of CO$_2$ ice, along with subtle absorption features around 2.2 $\mu$m. The two innermost satellites, Miranda and Ariel, also possess surfaces heavily modified by past endogenic activity. Previous observations of the smallest satellite, Miranda, have not detected the presence of CO$_2$ ice, and a report of an absorption feature at 2.2 $\mu$m has not been confirmed. An absorption feature at 2.2 $\mu$m could result from exposed or emplaced NH$_3$- or NH$_4$-bearing species, which have a limited lifetime on Miranda's surface, and therefore may imply that Miranda's internal activity was relatively recent. In this work, we analyzed near-infrared spectra of Miranda to determine whether CO$_2$ ice and the 2.2-$\mu$m feature are present. We measured the band area and depth of the CO$_2$ ice triplet (1.966, 2.012, and 2.070 $\mu$m), a weak 2.13-$\mu$m band attributed to CO$_2$ ice mixed with H$_2$O ice, and the 2.2-$\mu$m band. We confirmed a prior detection of a 2.2-$\mu$m band on Miranda, but we found no evidence for CO$_2$ ice, either as discrete deposits or mixed with H$_2$O ice. We compared a high signal-to-noise spectrum of Miranda to synthetic and laboratory spectra of various candidate compounds to shed light on what species may be responsible for the 2.2-$\mu$m band. We conclude that the 2.2-$\mu$m absorption is best matched by a combination of NH$_3$ ice with NH$_3$-hydrates or NH$_3$-H$_2$O mixtures. NH$_4$-bearing salts like NH$_4$Cl are also promising candidates that warrant further investigation.Comment: 29 pages, 10 figures. Accepted for publication in Planetary Science Journa