The physical basis for Parrondo's games

Several authors have implied that the original inspiration for Parrondo's games was a physical system called a ``flashing Brownian ratchet''. The relationship seems to be intuitively clear but, surprisingly, has not yet been established with rigor. In this paper, we apply standard finite-difference methods of numerical analysis to the Fokker-Planck equation. We derive a set of finite difference equations and show that they have the same form as Parrondo's games. Parrondo's games, are in effect, a particular way of sampling a Fokker-Planck equation. Physical Brownian ratchets have been constructed and have worked. It is hoped that the finite element method presented here will be useful in the simulation and design of flashing Brownian ratchets.Comment: 10 pages and 2 figure

Agreement between mothers and children with malocclusion in rating children's oral health-related quality of life

Introduction: The aim of this study was to compare the assessment of oral health-related quality of life (OH-QoL) between children with malocclusion and their mothers, by using responses to the child perceptions questionnaire and the parental-caregivers perceptions questionnaire. Methods: The study was conducted in 90 children, aged 11 to 14 years, with a malocclusion grade of 4 or 5 according to the index of orthodontic treatement need dental health component. The children and their mothers completed the questionnaires independently. Results: The mean ratings were similar for total scores (children, 20.4; mothers, 20.1), oral symptoms (children, 5.2; mothers, 4.7), and social well-being (children, 4.3; mothers, 4.8). However, the mothers group had a lower mean score for functional limitations (children, 5.3; mothers, 3.6) and a higher mean score for emotional well-being (children, 5.6; mothers, 7.1). The correlations between children's and mothers' responses ranged from rs = 0.545 for total score and emotional well-being to rs = 0.357 for functional limitations. There were good correlations between their responses to global (rs = 0.466) and life overall (rs = 0.427) questions, but poor correlations between the 2 questions, suggesting that these concepts were considered differently. Conclusions: Maternal opinions were similar to those of their children for the overall impact on OH-QoL of malocclusion, but mothers were more dissatisfied with the appearance of their children's teeth and overestimated the emotional impact of malocclusion. It would be useful to develop a specific measure to assess OH-QoL in children with malocclusion. (Am J Orthod Dentofacial Orthop 2010;137:631-8

Photonic Quantum Logic with Narrowband Light from Single Atoms

Increasing control of single photons enables new applications of photonic quantum-enhanced technology and further experimental exploration of fundamental quantum phenomena. Here, we demonstrate quantum logic using narrow linewidth photons that are produced under nearly perfect quantum control from a single ^87Rb atom strongly coupled to a high-finesse cavity. We use a controlled- NOT gate integrated into a photonic chip to entangle these photons, and we observe non-classical correlations between events separated by periods exceeding the travel time across the chip by three orders of magnitude. This enables quantum technology that will use the properties of both narrowband single photon sources and integrated quantum photonics, such as networked quantum computing, narrow linewidth quantum enhanced sensing and atomic memories.Comment: 5 pates, 3 figure

American Ginseng Modifies 137Cs-Induced DNA Damage and Oxidative Stress in Human Lymphocytes

The multifold bioactive medicinal properties of ginseng have been closely linked to its antioxidative ability, which is related to its ginsenoside content. Since the key mechanism of radiation-induced cell death and tissue damage is the generation of reactive oxygen species (ROS) that attack cellular DNA, this study focuses on the impact of a standardized North American ginseng extract (NAGE) on 137Cs-induced oxidative stress in human peripheral lymphocytes (PBL) obtained from 10 healthy individuals (6M/4F), 42.7 ± 4.6 years of age. At two different time points (0 h and 24 h before irradiation), we applied NAGE (250 - 1000 µg ml-1) to mononuclear cell cultures for cytokinesisblock micronuclei (MN) assay and determination of the state of oxidative stress in PBL. We found that at both time points, NAGE significantly reduced the MN yields in PBL after irradiation (1 and 2 Gy) in a concentration-dependent manner (P<0.001). Compared with radiation alone, the maximum reduction rate of MN yield were 51.1% and 49.1% after 1 Gy and 2 Gy exposures, respectively. We also found that before irradiation the presence of NAGE in the culture medium resulted in a significant increased intracellular total antioxidant capacity (TAC) in PBL. At both time points, the increment of 137Cs-induced MN yields in PBL was positively correlated with the increment of intracellular ROS production (R = 0.6 - 0.7, P = 0.002), but negatively correlated with the reduction of TAC levels (R = -0.4 - 0.5, P = 0.02 - 0.004). However, the presence of NAGE in the culture medium significantly increased the TAC levels, while concomitantly decreasing both ROS production and MN yields in PBL (P<0.001). Our findings that NAGE is effective in protecting human PBL against radiation-induced oxidative stress should encourage further in vivo study of dietary supplementation with NAGE as an effective natural radiation countermeasure. Originally published Open Nuclear Medicine Journal Vol 1 No. 1, 2009

Self-reported health and cardiovascular reactions to psychological stress in a large community sample: Cross-sectional and prospective associations

Exaggerated cardiovascular reactions to acute psychological stress have been implicated in a number of adverse health outcomes. This study examined, in a large community sample, the cross-sectional and prospective associations between reactivity and self-reported health. Blood pressure and heart rate were measured at rest and in response to an arithmetic stress task. Self-reported health was assessed concurrently and five years later. In cross-sectional analyses, those with excellent/good self-reported health exhibited larger cardiovascular reactions than those with fair/poor subjective health. In prospective analyses, participants who had larger cardiovascular reactions to stress were more likely to report excellent/good health five years later, taking into account their reported health status at the earlier assessment. The findings suggest that greater cardiovascular reactivity may not always be associated with negative health outcomes

Radioprotective Effect of American Ginseng on Human Lymphocytes at 90 Minutes Post-irradiation: A Study of 40 Cases

Backgroundâ Ionizing radiation (IR) initiates intracellular oxidative stress through enhanced formation of reactive oxygen species (ROS) that attack DNA leading to cell death. As the diversity of IR applied in medicine, agriculture, industry, and the growing threats of global terrorism, the acquisition of radioprotectors is an urgent need for the nation. However, the applicability of radioprotectors currently under investigation is limited due to their inherent toxicity. Objectiveâ This study investigated the effect of a standardized North American ginseng extract (NAGE, total ginsenoside content: 11.7%) on DNA damage in human lymphocytes at 90 min postirradiation. Designâ With the application of NAGE (250 â 1000 μg mlâ 1) at 90 min post-irradiation (1 and 2 Gy), DNA damage in lymphocytes obtained from 40 healthy individuals was evaluated by cytokinesis-block micronucleus (CBMN) assay. Similar experiments were also performed in lymphocytes treated with WR-1065 (1 mM or 3mM). In addition, before and after irradiation, lymphocytes obtained from 10 individuals were measured for their total antioxidant capacity (TAC) and the reactive oxygen species (ROS). Resultsâ The significant effect of NAGE against 137Cs-induced MN in lymphocytes is concentration-dependent. NAGE (750 μg mlâ 1) reduced MN yield by 50.7% after 1 Gy and 35.9% after 2 Gy exposures, respectively; these results were comparable to that of WR-1065. Further, we also found that NAGE reduces MN yield and ROS but increases TAC in lymphocytes. Conclusionsâ Our results suggest that NAGE is a relatively non-toxic natural compound that holds radioprotective potential in human lymphocytes even when applied at 90 min post-irradiation. One of the radioprotective mechanisms may be mediated through the scavenging of free radicals and enhancement of the intracellular TAC. Originally published Journal of Alternative and Complementary Medicine Vol. 16, No. 5 2010

The Empirical Landscape of Trade Policy

This chapter surveys empirically the broad features of trade policy in goods for 31 major economies that collectively represented 83 percent of the world's population and 91 percent of the world's GDP in 2013. We address five questions: Do some countries have more liberal trading regimes than others? Within countries, which industries receive the most import protection? How do trade policies change over time? Do countries discriminate among their trading partners when setting trade policy? Finally, how liberalized is world trade? Our analysis documents the extent of cross-sectional heterogeneity in applied commercial policy across countries, their economic sectors, and their trading partners, over time. We conclude that substantial trade policy barriers remain as an important feature of the world economy.antidumpin

Clinical prevalence of Lewy body dementia.

BACKGROUND: The prevalence of dementia with Lewy bodies (DLB) and dementia in Parkinson's disease (PDD) in routine clinical practice is unclear. Prevalence rates observed in clinical and population-based cohorts and neuropathological studies vary greatly. Small sample sizes and methodological factors in these studies limit generalisability to clinical practice. METHODS: We investigated prevalence in a case series across nine secondary care services over an 18-month period, to determine how commonly DLB and PDD cases are diagnosed and reviewed within two regions of the UK. RESULTS: Patients with DLB comprised 4.6% (95% CI 4.0-5.2%) of all dementia cases. DLB was represented in a significantly higher proportion of dementia cases in services in the North East (5.6%) than those in East Anglia (3.3%; χ2 = 13.6, p < 0.01). DLB prevalence in individual services ranged from 2.4 to 5.9%. PDD comprised 9.7% (95% CI 8.3-11.1%) of Parkinson's disease cases. No significant variation in PDD prevalence was observed between regions or between services. CONCLUSIONS: We found that the frequency of clinical diagnosis of DLB varied between geographical regions in the UK, and that the prevalence of both DLB and PDD was much lower than would be expected in this case series, suggesting considerable under-diagnosis of both disorders. The significant variation in DLB diagnostic rates between these two regions may reflect true differences in disease prevalence, but more likely differences in diagnostic practice. The systematic introduction of more standardised diagnostic practice could improve the rates of diagnosis of both conditions

Papua New Guinea terrestrial vertebrate richness: elevation matters most for all except reptiles

Aims To examine species richness patterns in Papua New Guinea’s terrestrial vertebrates and test for geographical congruence between the four classes, and between lizard and snake subgroups. To assess the environmental correlates of Papua New Guinean terrestrial-vertebrate richness, and contrast effects of varying analytical resolution and correction for spatial autocorrelation. We predict congruence in the bird, mammal and to a lesser extent amphibian richness, with weak congruence or incongruence between reptiles and the other taxonomic groups. We further predict these patterns will stem from relative or in the case of reptiles dissimilar, correlative trends with environmental predictors such as elevation and temperature. Location Papua New Guinea. Methods Having created and updated distribution maps for reptiles, we compare them with known ranges of amphibians, birds and mammals and generate species richness grids at quarter-, half- and one- degree spatial resolutions. We examine congruence in species richness between vertebrate groups and between reptile subgroups. We employed spreading-dye models to simulate species richness according to eight environmental predictors and one random model. We accounted for spatial autocorrelation in all analyses. Results Papua New Guinean amphibian, bird and mammal species richness are spatially congruent, a trend which strengthens with decreasing spatial resolution. Reptiles and the lizard and snake subgroups reveal remarkably different spatial-richness trends. Elevational predictors, particularly elevational range at coarse resolutions, provide the strongest correlates of species richness. Terrestrial-vertebrate richness increases with elevation, whereas reptile richness decreases. Main conclusions Congruent species richness gradients in Papua New Guinea are observed in most terrestrial vertebrates, except reptiles. Topographic heterogeneity and associated climatic clines promote diversity in most terrestrial vertebrates but appear to strongly constrain reptile diversity. The topographical complexity and climatic stratification of tropical mountains clearly present a wealth of opportunities for diversification in most terrestrial vertebrate groups. As reptiles are strongly constrained by temperature, tropical mountains present more of a diversification barrier for them

The effect of knowledge on healthcare professionals' perceptions of obesity

Aims: We aim to investigate the link between obesity prejudice and knowledge of obesity, and any differences in prejudice and knowledge amongst healthcare professional (HCP) groups. Methods: A survey consisting of two previously validated questionnaires assessing obesity prejudice (Attitudes Towards Obese Persons, ATOP1) and knowledge (Obesity Risk Knowledge Scale, ORK-102) were sent to HCP groups in an East Anglian NHS trust. An R2 coefficient was used to determine a correlation between the two scores, and one-way analysis of variance (ANOVA) to assess differences between HCP groups. Results: 436 responses were received, 372 of which were complete and analysed. HCP groups included consultants, junior doctors, nurses, health care assistants, operating department professionals, and pharmacists. The average ATOP and ORK-10 scores were 69.1/120 and 7.09/10 respectively. A statistically significant difference was found between HCP groups' ORK-10 scores (p < 0.05); there was no statistically significant difference demonstrated between the ATOP scores (p = 0.50). Conclusions: Obesity prejudice was demonstrated amongst HCPs, although this did not correlate with knowledge of obesity. Knowledge of obesity was low amongst many HCPs and could be improved via targeted educational strategies aiming to aid staff in the care of people with obesity