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

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

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

Wood Frog (Rana sylvatica) Use of Wildlife Ponds in Northcentral Arkansas

Forty-one wildlife ponds were monitored between 1988 and 1992 for breeding use by wood frogs (Rana sylvatica). Data were collected on egg deposition and pond characteristics. Breeding activity and characteristics were similar to that reported in other portions of the range of the wood frog. We also monitored 15 newly-constructed ponds to determine chronological breeding patterns. Data collected for each site indicated a significant increase (P\u3c 0.05) in the number of egg masses deposited in ponds as they age from 1-3 years during our study period. Increased chronological use of newly-constructed ponds may be due to localized population increase resulting from greater availability of breeding habita

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

The Role of ctDNA in Gastric Cancer.

Circulating tumour DNA (ctDNA) has potential applications in gastric cancer (GC) with respect to screening, the detection of minimal residual disease (MRD) following curative surgery, and in the advanced disease setting for treatment decision making and therapeutic monitoring. It can provide a less invasive and convenient method to capture the tumoural genomic landscape compared to tissue-based next-generation DNA sequencing (NGS). In addition, ctDNA can potentially overcome the challenges of tumour heterogeneity seen with tissue-based NGS. Although the evidence for ctDNA in GC is evolving, its potential utility is far reaching and may shape the management of this disease in the future. This article will review the current and future applications of ctDNA in GC