1,091 research outputs found

    Intermittency in Branching Processes

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    We study the intermittency properties of two branching processes, one with a uniform and another with a singular splitting kernel. The asymptotic intermittency indices, as well as the leading corrections to the asymptotic linear regime are explicitly computed in an analytic framework. Both models are found to possess a monofractal spectrum with φq=q−1\varphi_{q}=q-1. Relations with previous results are discussed.Comment: 20 pages, UCLA93/TEP/2

    Quantifying the ultraslow desorption kinetics of 2,6-naphthalenedicarboxylic acid monolayers at liquid–solid interfaces

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    Kinetic effects in monolayer self-assembly at liquid–solid interfaces are not well explored but can provide unique insights. We use variable-temperature scanning tunneling microscopy (STM) to quantify the desorption kinetics of 2,6-naphthalenedicarboxylic acid (NDA) monolayers at nonanoic acid–graphite interfaces. Quantitative tracking of the decline of molecular coverages by STM between 57.5 and 65.0 °C unveiled single-exponential decays over the course of days. An Arrhenius plot of rate constants derived from fits results in a surprisingly high energy barrier of 208 kJ mol–1 that strongly contrasts with the desorption energy of 16.4 kJ mol–1 with respect to solution as determined from a Born–Haber cycle. This vast discrepancy indicates a high-energy transition state. Expanding these studies to further systems is the key to pinpointing the molecular origin of the remarkably large NDA desorption barrier

    Playing with social and emotional game companions

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    This paper presents the findings of an empirical study that explores player game experience by implementing the ERiSA Framework in games. A study with Action Role-Playing Game (RPG) was designed to evaluate player interactions with game companions, who were imbued with social and emotional skill by the ERiSA Framework. Players had to complete a quest in the Skyrim game, in which players had to use social and emotional skills to obtain a sword. The results clearly show that game companions who are capable of perceiving and exhibit emotions, are perceived to have personality and can forge relationships with the players, enhancing the player experience during the game

    What can be inferred from moiré patterns? A case study of trimesic acid monolayers on graphite

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    Self-assembly of benzene-1,3,5-tricarboxylic acid (trimesic acid - TMA) monolayers at the alkanoic acid-graphite interface is revisited. Even though this archetypal model system for hydrogen bonded porous networks is particularly well studied, the analysis of routinely observed superperiodic contrast modulations known as moiré patterns lags significantly behind. Fundamental questions remain unanswered: Are moiré periodicity and orientation always the same, i.e. is exclusively only one specific moiré pattern observed? What are the geometric relations (superstructure matrices) between moiré, TMA, and graphite lattices? What affects the moiré pattern formation? Is there any influence of solvent, conentration, or thermal treatment? These basic questions are addressed by Scanning Tunneling Microscopy experiments at the liquid-solid interface, revealing a variety of different moiré patterns. Interestingly, TMA and graphite lattices were always found to be ~5° rotated with respect to each other. Consequently, the observed variation in moiré patterns is attributed to minute deviations (<2°) from this preferred orientation. Quantitaive analysis of moiré periods and orientations facilitates determination of the TMA lattice parameter with picometer precsion

    Origin of solvent-induced polymorphism in self-assembly of trimesic acid monolayers at solid-liquid interfaces

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    Encoding information in the chemical structure of tectons is the pivotal strategy in self-assembly for the realization of targeted supramolecular structures. However, frequently observed polymorphism in supramolecular monolayers provides experimental evidence for a decisive additional influence of environmental parameters, such as solute concentration or type of solvent, on structure selection. While concentration-induced polymorphism is comparatively well understood, the thermodynamical and molecular origins of solvent-induced polymorphism remain elusive. To shed light on this fundamental aspect of self-assembly, we explore the solvent-induced polymorphism of trimesic acid (TMA) monolayers on graphite as prototypical example. Using the homologous series of fatty acids as solvents, TMA self-assembles into the anticipated chickenwire polymorph for longer chain fatty acids, whereas the more densely packed, but still porous flower polymorph emerges in shorter chain fatty acids. According to our initial working hypothesis, the origin of this solvent-induced polymorphism lies in a solvent-dependence of the free energy gain. Utilizing an adapted Born-Haber cycle constructed from measured TMA sublimation and dissolution enthalpies as well as Density Functional Theory calculated monolayer binding energies, we quantitatively assessed the self-assembly thermodynamics of both polymorphs in hexanoic, heptanoic, and nonanoic acid. Yet, in contrast to the experimental findings, these results suggest superior thermodynamical stability of the chickenwire polymorph in all solvents. On the other hand, additional experiments comprising variable temperature Scanning Tunneling Microscopy corroborate that the flower polymorph is thermodynamically most stable in hexanoic acid. To resolve this apparent contradiction, we propose a thermodynamical stabilization of the flower polymorph in hexanoic acid through the stereochemically specific co-adsorption of shape-matched solvent molecules in its unique smaller elongated pores. This alternative explanation gains further support from experiments with side-substituted hexanoic acid solvents. Combination of a quantitative thermodynamic analysis and studies with systematic variations of the solvent’s molecular structure holds great promise to enhance the understanding of thus far underexplored solvent effects

    The effect of DAFNE education, continuous subcutaneous insulin infusion, or both in a population with type 1 diabetes in Scotland

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    Aim: To investigate the effect of DAFNEand continuous subcutaneous insulin infusion in clinical practice. Methods: Within NHS Lothian, continuous subcutaneous insulin infusion started in 2004 and DAFNE education began in 2006. We extracted anonymized data from the national database for all those aged &gt; 18 years with type 1 diabetes having a Dose Adjustment For Normal Eating course or continuous subcutaneous insulin infusion start date (n = 4617). Results: In total, 956 persons received DAFNEeducation, and 505 had received an insulin pump, 208 of whom had DAFNE education followed by insulin pump. Mean (SD) HbA1c before DAFNE education was 68 (15) mmol/mol (8.4% [1.4%]) and 66 (13) mmol/mol (8.2% [1.2%]) before continuous subcutaneous insulin infusion. In the year following DAFNE education, the mean fall in within‐person HbA1c was 3.8 mmol/mol (95% CI 4.0 to 3.4; 0.3% [0.4% to 0.3%]). Those with the poorest control (HbA1c ≄ 85 mmol/mol [9.9%]) experienced the largest decline (15.7 mmol/mol [1.4%]). Those in the lowest HbA1c band at initiation (&lt; 53 mmol/mmol [7.0%]) experienced a rise. In the year following continuous subcutaneous insulin infusion initiation there was a mean fall in within‐person HbA1c of 6.6 mmol/mol (6.8 to 6.4; 0.6% [0.6% to 0.6%]). In those with the poorest control (HbA1c ≄ 85 mmol/mol [9.9%]), the mean fall in HbA1c was 22.2 mmol/mol (23 to 21; 2.0% [2.1% to 1.9%]). Continuous subcutaneous insulin infusion effectiveness was not different with or without DAFNE education. The effects of both interventions were sustained over 5 years. Conclusions: Both DAFNE education and insulin pump therapy had the greatest effect on HbA1c in those with higher baseline values. There was little difference to attained HbA1c when Dose Adjustment For Normal Eating education was introduced before insulin pump therapy

    It is Hobbes, not Rousseau:an experiment on voting and redistribution

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    We perform an experiment which provides a laboratory replica of some important features of the welfare state. In the experiment, all individuals in a group decide whether to make a costly effort, which produces a random (independent) outcome for each one of them. The group members then vote on whether to redistribute the resulting and commonly known total sum of earnings equally amongst themselves. This game has two equilibria, if played once. In one of them, all players make effort and there is little redistribution. In the other one, there is no effort and nothingWe thank Iris Bohnet, Tim Cason, David Cooper, John Duffy, Maia Guell, John Van Huyck and Robin Mason for helpful conversations and encouragement. The comments of the Editor and two referees helped improve the paper. We gratefully acknowledge the financial support from Spain’s Ministry of Science and Innovation under grants CONSOLIDER INGENIO 2010 CSD2006-0016 (all authors), ECO2009-10531 (Cabrales), ECO2008-01768 (Nagel) and the Comunidad de Madrid under grant Excelecon (Cabrales), the Generalitat de Catalunya and the CREA program (Nagel), and project SEJ2007-64340 of Spain’s Ministerio de Educación y Ciencia (Rodríguez Mora).Publicad

    Gradient methods for problems with inexact model of the objective

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    We consider optimization methods for convex minimization problems under inexact information on the objective function. We introduce inexact model of the objective, which as a particular cases includes inexact oracle [19] and relative smoothness condition [43]. We analyze gradient method which uses this inexact model and obtain convergence rates for convex and strongly convex problems. To show potential applications of our general framework we consider three particular problems. The first one is clustering by electorial model introduced in [49]. The second one is approximating optimal transport distance, for which we propose a Proximal Sinkhorn algorithm. The third one is devoted to approximating optimal transport barycenter and we propose a Proximal Iterative Bregman Projections algorithm. We also illustrate the practical performance of our algorithms by numerical experiments

    Infectious Disease Ontology

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    Technological developments have resulted in tremendous increases in the volume and diversity of the data and information that must be processed in the course of biomedical and clinical research and practice. Researchers are at the same time under ever greater pressure to share data and to take steps to ensure that data resources are interoperable. The use of ontologies to annotate data has proven successful in supporting these goals and in providing new possibilities for the automated processing of data and information. In this chapter, we describe different types of vocabulary resources and emphasize those features of formal ontologies that make them most useful for computational applications. We describe current uses of ontologies and discuss future goals for ontology-based computing, focusing on its use in the field of infectious diseases. We review the largest and most widely used vocabulary resources relevant to the study of infectious diseases and conclude with a description of the Infectious Disease Ontology (IDO) suite of interoperable ontology modules that together cover the entire infectious disease domain
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