Fractal Markets Hypothesis and the Global Financial Crisis: Scaling, Investment Horizons and Liquidity

We investigate whether fractal markets hypothesis and its focus on liquidity and invest- ment horizons give reasonable predictions about dynamics of the financial markets during the turbulences such as the Global Financial Crisis of late 2000s. Compared to the mainstream efficient markets hypothesis, fractal markets hypothesis considers financial markets as com- plex systems consisting of many heterogenous agents, which are distinguishable mainly with respect to their investment horizon. In the paper, several novel measures of trading activity at different investment horizons are introduced through scaling of variance of the underlying processes. On the three most liquid US indices - DJI, NASDAQ and S&P500 - we show that predictions of fractal markets hypothesis actually fit the observed behavior quite well.Comment: 11 pages, 3 figure

The potential of low-intensity and online interventions for depression in low- and middle-income countries

The World Health Organization (WHO) reports that low- and middle-income countries (LMICs) are confronted with a serious ‘mental health gap’, indicating an enormous disparity between the number of individuals in need of mental health care and the availability of professionals to provide such care (WHO in 2010). Traditional forms of mental health services (i.e. face-to-face, individualised assessments and interventions) are therefore not feasible. We propose three strategies for addressing this mental health gap: delivery of evidence-based, low-intensity interventions by non-specialists, the use of transdiagnostic treatment protocols, and strategic deployment of technology to facilitate access and uptake. We urge researchers from all over the world to conduct feasibility studies and randomised controlled studies on the effect of low-intensity interventions and technology supported (e.g. online) interventions in LMICs, preferably using an active control condition as comparison, to ensure we disseminate effective treatments in LMICs

Literacy teaching with tablets in bilingual primary classrooms : the Malta tabLit study

We would like to thank the teachers and students who participated in our study.This chapter outlines the ways in which teachers in five primary classrooms in Malta used tablets over the six months for the teaching of bilingual literacy. The official policy, as outlined in the National Literacy Strategy for Malta, is of balanced literacy teaching and learning in the two languages of schooing in Malta: Maltese and English. Teachers’ planning and preparation, the classroom environment, instruction and pedagogy were documented using a focus group, classroom observations, teacher interviews and reflective diaries and student questionnaires. Findings showed that the teachers integrated the use of tablets in their teaching for a number of creative literacy activities in the two languages, including reading comprehension, and guided and creative writing. The chapter concludes with recommendations for teachers’ professional development, including school-based professional and technological support and ways to strengthen school-home links with the use of tablets.peer-reviewe

Random matrix approach in search for weak signals immersed in background noise

We present new, original and alternative method for searching signals coded in noisy data. The method is based on the properties of random matrix eigenvalue spectra. First, we describe general ideas and support them with results of numerical simulations for basic periodic signals immersed in artificial stochastic noise. Then, the main effort is put to examine the strength of a new method in investigation of data content taken from the real astrophysical NAUTILUS detector, searching for the presence of gravitational waves. Our method discovers some previously unknown problems with data aggregation in this experiment. We provide also the results of new method applied to the entire respond signal from ground based detectors in future experimental activities with reduced background noise level. We indicate good performance of our method what makes it a positive predictor for further applications in many areas.Comment: 15 pages, 16 figure

Exploring the functional landscape of the fission yeast genome via Hermes transposon mutagenesis

In general, the non-protein-coding dark matter of eukaryotic genomes remains poorly understood. Neither diversity studies, comparative genomics, nor the biochemical outputs allow fine-scale descriptions of the genomic elements that are required for an organism to grow. Transposon mutagenesis offers an alternative approach to locate functional regions. In principle, insertion mutants are created in large pools, and mutants harbouring harmful insertions are quantitatively removed from the population. Subsequent sequencing of mutant libraries should reveal functionality in regions with fewer insertions. Transposon mutagenesis works well in bacteria. We applied the Hermes transposon system to locate functional regions in the Schizosaccharomyces pombe, or fission yeast genome. We created multiple dense insertion libraries, during log phase growth and chronological ageing, achieving a saturating (or near-saturating) insertion density of 1 insertion per 13 nucleotides of the genome for log phase samples. To account for the complexity and stochastic nature of the data, we applied a five-state hidden Markov model (HMM) that includes generalised linear models to account for systematic insertion biases (e.g. nucleosomes). The HMM state provides a semi-quantitative estimate of the functional significance of the genome at single nucleotide-level resolution. The HMM state values are strikingly consistent (but more detailed than) genome annotations. Here, we show that transposon insertions have functional consequences in 90% of the genome, including 80% of the non-protein-coding regions. Specifically, we discover 85 essential ncRNAs during vegetative growth, and 218 during ageing. We also find 54 pro-ageing and 136 anti-ageing genes. Overall, this functional annotation map distinguishes sub gene-level genomic segments that have differential effects on cell survival, and so will have extensive utility to the community

Cumulative human impacts on coral reefs: assessing risk and management implications for Brazilian coral reefs

Effective management of coral reefs requires strategies tailored to cope with cumulative disturbances from human activities. In Brazil, where coral reefs are a priority for conservation, intensifying threats from local and global stressors are of paramount concern to management agencies. Using a cumulative impact assessment approach, our goal was to inform management actions for coral reefs in Brazil by assessing their exposure to multiple stressors (fishing, land-based activities, coastal development, mining, aquaculture, shipping, and global warming). We calculated an index of the risk to cumulative impacts: (i) assuming uniform sensitivity of coral reefs to stressors; and (ii) using impact weights to reflect varying tolerance levels of coral reefs to each stressor. We also predicted the index in both the presence and absence of global warming. We found that 16% and 37% of coral reefs had high to very high risk of cumulative impacts, without and with information on sensitivity respectively, and 42% of reefs had low risk to cumulative impacts from both local and global stressors. Our outputs are the first comprehensive spatial dataset of cumulative impact on coral reefs in Brazil, and show that areas requiring attention mostly corresponded to those closer to population centres. We demonstrate how the relationships between risks from local and global stressors can be used to derive strategic management actions

Roughness and Finite Size Effect in the NYSE Stock-Price Fluctuations

We consider the roughness properties of NYSE (New York Stock Exchange) stock-price fluctuations. The statistical properties of the data are relatively homogeneous within the same day but the large jumps between different days prevent the extension of the analysis to large times. This leads to intrinsic finite size effects which alter the apparent Hurst (H) exponent. We show, by analytical methods, that finite size effects always lead to an enhancement of H. We then consider the effect of fat tails on the analysis of the roughness and show that the finite size effects are strongly enhanced by the fat tails. The non stationarity of the stock price dynamics also enhances the finite size effects which, in principle, can become important even in the asymptotic regime. We then compute the Hurst exponent for a set of stocks of the NYSE and argue that the interpretation of the value of H is highly ambiguous in view of the above results. Finally we propose an alternative determination of the roughness in terms of the fluctuations from moving averages with variable characteristic times. This permits to eliminate most of the previous problems and to characterize the roughness in useful way. In particular this approach corresponds to the automatic elimination of trends at any scale.Comment: 13 pages, 11 fugure

Exact Results for the Roughness of a Finite Size Random Walk

We consider the role of finite size effects on the value of the effective Hurst exponent H. This problem is motivated by the properties of the high frequency daily stock-prices. For a finite size random walk we derive some exact results based on Spitzer's identity. The conclusion is that finite size effects strongly enhance the value of H and the convergency to the asymptotic value (H=1/2) is rather slow. This result has a series of conceptual and practical implication which we discuss.Comment: 5 pages, 3 figure

High-quality ion beams by irradiating a nano-structured target with a petawatt laser pulse

We present a novel laser based ion acceleration scheme, where a petawatt circularly polarized laser pulse is shot on an ultra-thin (nano-scale) double-layer target. Our scheme allows the production of high-quality light ion beams with both energy and angular dispersion controllable by the target properties. We show that extraction of all electrons from the target by radiation pressure can lead to a very effective two step acceleration process for light ions if the target is designed correctly. Relativistic protons should be obtainable with pulse powers of a few petawatt. Careful analytical modeling yields estimates for characteristic beam parameters and requirements on the laser pulse quality, in excellent agreement with one and two-dimensional Particle-in Cell simulations.Comment: 18 pages, 7 figures, accepted in New. J. Phy