389 research outputs found

    Exact Maximal Height Distribution of Fluctuating Interfaces

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    We present an exact solution for the distribution P(h_m,L) of the maximal height h_m (measured with respect to the average spatial height) in the steady state of a fluctuating Edwards-Wilkinson interface in a one dimensional system of size L with both periodic and free boundary conditions. For the periodic case, we show that P(h_m,L)=L^{-1/2}f(h_m L^{-1/2}) for all L where the function f(x) is the Airy distribution function that describes the probability density of the area under a Brownian excursion over a unit interval. For the free boundary case, the same scaling holds but the scaling function is different from that of the periodic case. Numerical simulations are in excellent agreement with our analytical results. Our results provide an exactly solvable case for the distribution of extremum of a set of strongly correlated random variables.Comment: 4 pages revtex (two-column), 1 .eps figure include

    Boundary driven zero-range processes in random media

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    The stationary states of boundary driven zero-range processes in random media with quenched disorder are examined, and the motion of a tagged particle is analyzed. For symmetric transition rates, also known as the random barrier model, the stationary state is found to be trivial in absence of boundary drive. Out of equilibrium, two further cases are distinguished according to the tail of the disorder distribution. For strong disorder, the fugacity profiles are found to be governed by the paths of normalized α\alpha-stable subordinators. The expectations of integrated functions of the tagged particle position are calculated for three types of routes.Comment: 23 page

    The Effect of Tobacco Control Mass Media Campaigns on Smoking-Related Behavior Among People With Mental Illness: A Systematic Literature Review

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    ntroductionTobacco control mass media campaigns (MMCs) can be effective generally, but little is known about their effects among people with mental illness. The objectives of this study were to systematically review: (1) Whether tobacco control MMCs affect smoking-related outcomes among people with mental illness. (2) Cost-effectiveness.Aims and MethodsData sources: MEDLINE, Embase, PsycInfo, Web of Science, CINAHL, the Cochrane Library (searched March 2021), reference lists of included articles and relevant systematic reviews. Study eligibility criteria: Population: Adults with mental illness and experience of smoking tobacco and/or using other nicotine-containing products. Intervention/exposure: Tobacco control MMC messages. Comparator: No exposure, other tobacco control intervention(s), no comparator. Primary outcome: Changes in quitting behaviors. Study design: All primary research. Quantitative data were appraised using the EPHPP tool, qualitative data using CASP’s Studies Checklist. Data were synthesized narratively.ResultsEight studies were included, seven were at high risk of bias. There was inconclusive evidence of the effect of MMCs on quit attempts and intentions to quit among people with mental illness. Increasing advertisement exposure did not increase quit attempts or intentions to quit among those with mental illness, however, increased exposure to an advertisement that addressed smoking and mental health did. None of the studies assessed cost-effectiveness.ConclusionsFindings should be interpreted with caution as data are limited and of low or moderate quality. There is evidence to suggest that tobacco control MMCs have limited impact on those with mental illness, although campaigns that are specific to smoking and mental health may be effective.ImplicationsThere is a paucity of good-quality evidence of the effect of tobacco control MMC messages among people with mental illness. Careful consideration should be given to the design of future studies that evaluate MMCs in order to minimize the risk of bias, establish causality, and ensure the findings reflect real-world implementation. Further research should examine the need for MMC messages that address mental health

    Airy Distribution Function: From the Area Under a Brownian Excursion to the Maximal Height of Fluctuating Interfaces

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    The Airy distribution function describes the probability distribution of the area under a Brownian excursion over a unit interval. Surprisingly, this function has appeared in a number of seemingly unrelated problems, mostly in computer science and graph theory. In this paper, we show that this distribution also appears in a rather well studied physical system, namely the fluctuating interfaces. We present an exact solution for the distribution P(h_m,L) of the maximal height h_m (measured with respect to the average spatial height) in the steady state of a fluctuating interface in a one dimensional system of size L with both periodic and free boundary conditions. For the periodic case, we show that P(h_m,L)=L^{-1/2}f(h_m L^{-1/2}) for all L where the function f(x) is the Airy distribution function. This result is valid for both the Edwards-Wilkinson and the Kardar-Parisi-Zhang interfaces. For the free boundary case, the same scaling holds P(h_m,L)=L^{-1/2}F(h_m L^{-1/2}), but the scaling function F(x) is different from that of the periodic case. We compute this scaling function explicitly for the Edwards-Wilkinson interface and call it the F-Airy distribution function. Numerical simulations are in excellent agreement with our analytical results. Our results provide a rather rare exactly solvable case for the distribution of extremum of a set of strongly correlated random variables. Some of these results were announced in a recent Letter [ S.N. Majumdar and A. Comtet, Phys. Rev. Lett., 92, 225501 (2004)].Comment: 27 pages, 10 .eps figures included. Two figures improved, new discussion and references adde

    An integrative framework of preemption strategies

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    Pre-print; author's draftThis paper performs a review of the various pre-emption strategies prescribed in the economics literature. These are cost superiority, consumers' switching cost, channel exclusivity, environmental barriers of entry and credible commitment to react aggressively. Through our analysis, we develop an integrative framework of the pre-emption strategies that will result in long-term payoffs to the firm. The framework proposes that there are two key dimensions—strategic advantage and strategic focus—and identify five generic types of pre-emption strategies for market incumbents. These are the switching cost, blockade, credible commitment, tie-up, and cost leadership strategies. The pre-emption strategies and the framework presented can assist managerial decision-making for the successful pre-emption of potential competition to complement their existing efforts

    Noncovalent Functionalization of Graphene and Graphene Oxide for Energy Materials, Biosensing, Catalytic, and Biomedical Applications

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    This Review focuses on noncovalent functionalization of graphene and graphene oxide with various species involving biomolecules, polymers, drugs, metals and metal oxide-based nanoparticles, quantum dots, magnetic nanostructures, other carbon allotropes (fullerenes, nanodiamonds, and carbon nanotubes), and graphene analogues (MoS2, WS2). A brief description of pi-pi interactions, van der Waals forces, ionic interactions, and hydrogen bonding allowing noncovalent modification of graphene and graphene oxide is first given. The main part of this Review is devoted, to tailored functionalization for applications in drug delivery, energy materials, solar cells, water splitting, biosensing, bioimaging, environmental, catalytic, photocatalytic, and biomedical technologies. A significant part of this Review explores the possibilities of graphene/graphene oxide-based 3D superstructures and their use in lithium-ion batteries. This Review ends with a look at challenges and future prospects of noncovalently modified graphene and graphene oxideope

    The sensitivity of qSOFA calculated at triage and during emergency department treatment to rapidly identify sepsis patients.

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    The quick sequential organ failure assessment (qSOFA) score has been proposed as a means to rapidly identify adult patients with suspected infection, in pre-hospital, Emergency Department (ED), or general hospital ward locations, who are in a high-risk category with increased likelihood of poor outcomes: a greater than 10% chance of dying or an increased likelihood of spending 3 or more days in the ICU. This score is intended to replace the use of systemic inflammatory response syndrome (SIRS) criteria as a screening tool; however, its role in ED screening and identification has yet to be fully elucidated. In this retrospective observational study, we explored the performance of triage qSOFA (tqSOFA), maximum qSOFA, and first initial serum lactate (\u3e 3 mmol/L) at predicting in-hospital mortality and compared these results to those for the initial SIRS criteria obtained in triage. A total of 2859 sepsis cases were included and the in-hospital mortality rate was 14.4%. The sensitivity of tqSOFA ≄ 2 and maximum qSOFA ≄ 2 to predict in-hospital mortality were 33% and 69%, respectively. For comparison, the triage SIRS criteria and the initial lactate \u3e 3 mmol/L had sensitivities of 82% and 65%, respectively. These results demonstrate that in a large ED sepsis database the earliest measurement of end organ impairment, tqSOFA, performed poorly at identifying patients at increased risk of mortality and maximum qSOFA did not significantly outperform initial serum lactate levels

    A cluster randomised feasibility study of an adolescent incentive intervention to increase uptake of HPV vaccination.

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    BACKGROUND: Uptake of human papillomavirus (HPV) vaccination is suboptimal among some groups. We aimed to determine the feasibility of undertaking a cluster randomised controlled trial (RCT) of incentives to improve HPV vaccination uptake by increasing consent form return. METHODS: An equal-allocation, two-arm cluster RCT design was used. We invited 60 London schools to participate. Those agreeing were randomised to either a standard invitation or incentive intervention arm, in which Year 8 girls had the chance to win a ÂŁ50 shopping voucher if they returned a vaccination consent form, regardless of whether consent was provided. We collected data on school and parent participation rates and questionnaire response rates. Analyses were descriptive. RESULTS: Six schools completed the trial and only 3% of parents opted out. The response rate was 70% for the girls' questionnaire and 17% for the parents'. In the intervention arm, 87% of girls returned a consent form compared with 67% in the standard invitation arm. The proportion of girls whose parents gave consent for vaccination was higher in the intervention arm (76%) than the standard invitation arm (61%). CONCLUSIONS: An RCT of an incentive intervention is feasible. The intervention may improve vaccination uptake but a fully powered RCT is needed.British Journal of Cancer advance online publication: 22 August 2017; doi:10.1038/bjc.2017.284 www.bjcancer.com

    On Combining Stated Preferences and Revealed Preferences Approaches to Evaluate Environmental Resources Having a Recreational Use

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    This work aims at analysing the value of recreational water uses for the Idro Lake (Lombardy, Northern Italy), which has been experiencing dramatic fluctuations in its levels in recent years, due to excessive productive withdrawal that affected recreational uses. It estimates the economic benefits deriving from recreational uses, by considering the current recreational demand and the hypothetical one obtained by considering an “improved quality” scenario. Through an on-site survey, we built a panel dataset. Following Whitehead et al. (2000) and Hanley et al. (2003) we get welfare estimates by combining SP and RP responses. The present CS is estimated in €134 per individual, whilst the increase in CS is estimated in €173 per individual. These figures can be confronted with the economic value of competitive uses and with the clean up costs, respectively, to infer some policy indications
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