1,166 research outputs found

    On Compound Poisson Processes Arising in Change-Point Type Statistical Models as Limiting Likelihood Ratios

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    Different change-point type models encountered in statistical inference for stochastic processes give rise to different limiting likelihood ratio processes. In a previous paper of one of the authors it was established that one of these likelihood ratios, which is an exponential functional of a two-sided Poisson process driven by some parameter, can be approximated (for sufficiently small values of the parameter) by another one, which is an exponential functional of a two-sided Brownian motion. In this paper we consider yet another likelihood ratio, which is the exponent of a two-sided compound Poisson process driven by some parameter. We establish, that similarly to the Poisson type one, the compound Poisson type likelihood ratio can be approximated by the Brownian type one for sufficiently small values of the parameter. We equally discuss the asymptotics for large values of the parameter and illustrate the results by numerical simulations

    Universality in Systems with Power-Law Memory and Fractional Dynamics

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    There are a few different ways to extend regular nonlinear dynamical systems by introducing power-law memory or considering fractional differential/difference equations instead of integer ones. This extension allows the introduction of families of nonlinear dynamical systems converging to regular systems in the case of an integer power-law memory or an integer order of derivatives/differences. The examples considered in this review include the logistic family of maps (converging in the case of the first order difference to the regular logistic map), the universal family of maps, and the standard family of maps (the latter two converging, in the case of the second difference, to the regular universal and standard maps). Correspondingly, the phenomenon of transition to chaos through a period doubling cascade of bifurcations in regular nonlinear systems, known as "universality", can be extended to fractional maps, which are maps with power-/asymptotically power-law memory. The new features of universality, including cascades of bifurcations on single trajectories, which appear in fractional (with memory) nonlinear dynamical systems are the main subject of this review.Comment: 23 pages 7 Figures, to appear Oct 28 201

    Performance Comparisons of Jet and Mesh Nebulizers Using Different Interfaces in Simulated Spontaneously Breathing Adults and Children

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    Background: Different types of nebulizers and interfaces are used for the treatment of adults and children with pulmonary diseases. The purpose of this study was to determine the efficiency of a mesh nebulizer (MN) with a proprietary adapter and a jet nebulizer (JN) under different configurations in adult and pediatric models of spontaneous breathing. We hypothesize that delivery efficiency of JN and MN will differ depending on the interface used during aerosol therapy in simulated spontaneously breathing adult and pediatric models. While we expect that aerosol delivery with JN will be less efficient than MN, we also hypothesize that lung deposition obtained with the adult lung model will be more than that with the pediatric lung model in all conditions tested in this study. Methods: A lung model using a teaching manikin connected to a sinusoidal pump via a collecting filter at the level of the bronchi simulating a spontaneously breathing adult (Vt 500 mL, RR 15 bpm, I:E ratio 1:2) or pediatric patient (Vt 150 mL, RR 25 bpm, I:E ratio 1:2). Albuterol sulfate (2.5 mg/3 mL) was aerosolized with JN (Mistymax 10, Airlife) or MN (Aerogen Solo®, Aerogen) with the Adapter (Aerogen Solo® Adapter, Aerogen Ltd, Galway, Ireland) using mouthpiece, aerosol mask, and valved-mask in adults and the dragon mask, aerosol mask, and valved-mask in pediatrics (n=3). The Adapter, specifically designed for MN, was attached to all the interfaces used in this study with supplemental oxygen of 2 lpm, and in addition, the MP was tested with no additional flow in the adult model. The JN was driven with 10 lpm based on the manufacturer\u27s label. Drug was eluted from the filter and analyzed via spectrophotometry. Descriptive statistics, dependent t-test and one-way analysis of variance were used for data analysis. Significant level was set at 0.05. Results: In adults, delivery efficiency of JN with the valved mask was significantly greater than that with the aerosol mask (p=0.01). Aerosol delivery of JN with the mouthpiece was not statistically significant from the valved mask (p=0.123) and the aerosol mask (p=0.193). Drug delivery with MN with mouthpiece (15.42±1.4%) and valved-mask (15.15±1.1%) was greater than the open aerosol mask (7.54±0.39%; p=0.0001) in the adult lung model. With no flow mouthpiece delivery increased\u3e2 fold (34.9±3.1%; p=.0001) compared to use of 2 lpm of flow. Using the JN with the pediatric model deposition with valved-mask (5.3±0.8%), dragon mask (4.7±0.9%), and aerosol mask (4.1±0.3%) were similar (p\u3e0.05); while drug delivery with MN via valved-mask (11.1±0.7%) was greater than the dragon mask (6.44±0.3%; p=0.002) and aerosol mask (4.6±0.4%; p=0.002), and the dragon mask was more efficient than the open aerosol mask (p=0.009) Conclusion: The type of nebulizer and interface used for aerosol therapy affects delivery efficiency in these simulated spontaneously breathing adult and pediatric models. Drug delivery was greatest with the valved-mouthpiece and mask with JN and MN, while the standard aerosol mask was least efficient in these simulated spontaneously breathing adult and pediatric lung models. Delivery efficiency of JN was less than MN in all conditions tested in this study except in the aerosol mask. Lung deposition obtained with the adult lung model was more than that with the pediatric lung model

    Protecting eyewitness evidence: Examining the efficacy of a self-administered interview tool

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    Given the crucial role of eyewitness evidence, statements should be obtained as soon as possible after an incident. This is not always achieved due to demands on police resources. Two studies trace the development of a new tool, the Self-Administered Interview (SAI), designed to elicit a comprehensive initial statement. In Study 1, SAI participants reported more correct details than participants who provided a free recall account, and performed at the same level as participants given a Cognitive Interview. In Study 2, participants viewed a simulated crime and half recorded their statement using the SAI. After a delay of 1 week, all participants completed a free recall test. SAI participants recalled more correct details in the delayed recall task than control participants

    A Pair of Dopamine Neurons Target the D1-Like Dopamine Receptor DopR in the Central Complex to Promote Ethanol-Stimulated Locomotion in Drosophila

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    Dopamine is a mediator of the stimulant properties of drugs of abuse, including ethanol, in mammals and in the fruit fly Drosophila. The neural substrates for the stimulant actions of ethanol in flies are not known. We show that a subset of dopamine neurons and their targets, through the action of the D1-like dopamine receptor DopR, promote locomotor activation in response to acute ethanol exposure. A bilateral pair of dopaminergic neurons in the fly brain mediates the enhanced locomotor activity induced by ethanol exposure, and promotes locomotion when directly activated. These neurons project to the central complex ellipsoid body, a structure implicated in regulating motor behaviors. Ellipsoid body neurons are required for ethanol-induced locomotor activity and they express DopR. Elimination of DopR blunts the locomotor activating effects of ethanol, and this behavior can be restored by selective expression of DopR in the ellipsoid body. These data tie the activity of defined dopamine neurons to D1-like DopR-expressing neurons to form a neural circuit that governs acute responding to ethanol

    A new implicit review instrument for measuring quality of care delivered to pediatric patients in the emergency department

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    BackgroundThere are few outcomes experienced by children receiving care in the Emergency Department (ED) that are amenable to measuring for the purposes of assessing of quality of care. The purpose of this study was to develop, test, and validate a new implicit review instrument that measures quality of care delivered to children in EDs.MethodsWe developed a 7-point structured implicit review instrument that encompasses four aspects of care, including the physician's initial data gathering, integration of information and development of appropriate diagnoses; initial treatment plan and orders; and plan for disposition and follow-up. Two pediatric emergency medicine physicians applied the 5-item instrument to children presenting in the highest triage category to four rural EDs, and we assessed the reliability of the average summary scores (possible range of 5-35) across the two reviewers using standard measures. We also validated the instrument by comparing this mean summary score between those with and without medication errors (ascertained independently by two pharmacists) using a two-sample t-test.ResultsWe reviewed the medical records of 178 pediatric patients for the study. The mean and median summary score for this cohort of patients were 27.4 and 28.5, respectively. Internal consistency was high (Cronbach's alpha of 0.92 and 0.89). All items showed a significant (p < 0.005) positive correlation between reviewers using the Spearman rank correlation (range 0.24 to 0.39). Exact agreement on individual items between reviewers ranged from 70.2% to 85.4%. The Intra-class Correlation Coefficient for the mean of the total summary score across the two reviewers was 0.65. The validity of the instrument was supported by the finding of a higher score for children without medication errors compared to those with medication errors which trended toward significance (mean score = 28.5 vs. 26.0, p = 0.076).ConclusionThe instrument we developed to measure quality of care provided to children in the ED has high internal consistency, fair to good inter-rater reliability and inter-rater correlation, and high content validity. The validity of the instrument is supported by the fact that the instrument's average summary score was lower in the presence of medication errors, which trended towards statistical significance

    Failure of available scoring systems to predict ongoing infection in patients with abdominal sepsis after their initial emergency laparotomy

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    <p>Abstract</p> <p>Background</p> <p>To examine commonly used scoring systems, designed to predict overall outcome in critically ill patients, for their ability to select patients with an abdominal sepsis that have ongoing infection needing relaparotomy.</p> <p>Methods</p> <p>Data from a RCT comparing two surgical strategies was used. The study population consisted of 221 patients at risk for ongoing abdominal infection. The following scoring systems were evaluated with logistic regression analysis for their ability to select patients requiring a relaparotomy: APACHE-II score, SAPS-II, Mannheim Peritonitis Index (MPI), MODS, SOFA score, and the acute part of the APACHE-II score (APS).</p> <p>Results</p> <p>The proportion of patients requiring a relaparotomy was 32% (71/221). Only 2 scores had a discriminatory ability in identifying patients with ongoing infection needing relaparotomy above chance: the APS on day 1 (AUC 0.61; 95%CI 0.52-0.69) and the SOFA score on day 2 (AUC 0.60; 95%CI 0.52-0.69). However, to correctly identify 90% of all patients needing a relaparotomy would require such a low cut-off value that around 80% of all patients identified by these scoring systems would have negative findings at relaparotomy.</p> <p>Conclusions</p> <p>None of the widely-used scoring systems to predict overall outcome in critically ill patients are of clinical value for the identification of patients with ongoing infection needing relaparotomy. There is a need to develop more specific tools to assist physicians in their daily monitoring and selection of these patients after the initial emergency laparotomy.</p> <p>Trial registration number</p> <p>ISRCTN: <a href="http://www.controlled-trials.com/ISRCTN 51729393">ISRCTN 51729393</a></p

    A search for the decay modes B+/- to h+/- tau l

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    We present a search for the lepton flavor violating decay modes B+/- to h+/- tau l (h= K,pi; l= e,mu) using the BaBar data sample, which corresponds to 472 million BBbar pairs. The search uses events where one B meson is fully reconstructed in one of several hadronic final states. Using the momenta of the reconstructed B, h, and l candidates, we are able to fully determine the tau four-momentum. The resulting tau candidate mass is our main discriminant against combinatorial background. We see no evidence for B+/- to h+/- tau l decays and set a 90% confidence level upper limit on each branching fraction at the level of a few times 10^-5.Comment: 15 pages, 7 figures, submitted to Phys. Rev.

    Observation and study of baryonic B decays: B -> D(*) p pbar, D(*) p pbar pi, and D(*) p pbar pi pi

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    We present a study of ten B-meson decays to a D(*), a proton-antiproton pair, and a system of up to two pions using BaBar's data set of 455x10^6 BBbar pairs. Four of the modes (B0bar -> D0 p anti-p, B0bar -> D*0 p anti-p, B0bar -> D+ p anti-p pi-, B0bar -> D*+ p anti-p pi-) are studied with improved statistics compared to previous measurements; six of the modes (B- -> D0 p anti-p pi-, B- -> D*0 p anti-p pi-, B0bar -> D0 p anti-p pi- pi+, B0bar -> D*0 p anti-p pi- pi+, B- -> D+ p anti-p pi- pi-, B- -> D*+ p anti-p pi- pi-) are first observations. The branching fractions for 3- and 5-body decays are suppressed compared to 4-body decays. Kinematic distributions for 3-body decays show non-overlapping threshold enhancements in m(p anti-p) and m(D(*)0 p) in the Dalitz plots. For 4-body decays, m(p pi-) mass projections show a narrow peak with mass and full width of (1497.4 +- 3.0 +- 0.9) MeV/c2, and (47 +- 12 +- 4) MeV/c2, respectively, where the first (second) errors are statistical (systematic). For 5-body decays, mass projections are similar to phase space expectations. All results are preliminary.Comment: 28 pages, 90 postscript figures, submitted to LP0

    Objective quantification of nanoscale protein distributions

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    Nanoscale distribution of molecules within small subcellular compartments of neurons critically influences their functional roles. Although, numerous ways of analyzing the spatial arrangement of proteins have been described, a thorough comparison of their effectiveness is missing. Here we present an open source software, GoldExt, with a plethora of measures for quantification of the nanoscale distribution of proteins in subcellular compartments (e.g. synapses) of nerve cells. First, we compared the ability of five different measures to distinguish artificial uniform and clustered patterns from random point patterns. Then, the performance of a set of clustering algorithms was evaluated on simulated datasets with predefined number of clusters. Finally, we applied the best performing methods to experimental data, and analyzed the nanoscale distribution of different pre- and postsynaptic proteins, revealing random, uniform and clustered sub-synaptic distribution patterns. Our results reveal that application of a single measure is sufficient to distinguish between different distributions
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