259 research outputs found

    UCLCHEMCMC: A MCMC Inference tool for Physical Parameters of Molecular Clouds

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    We present the publicly available, open source code UCLCHEMCMC, designed to estimate physical parameters of an observed cloud of gas by combining Monte Carlo Markov Chain (MCMC) sampling with chemical and radiative transfer modeling. When given the observed values of different emission lines, UCLCHEMCMC runs a Bayesian parameter inference, using a MCMC algorithm to sample the likelihood and produce an estimate of the posterior probability distribution of the parameters. UCLCHEMCMC takes a full forward modeling approach, generating model observables from the physical parameters via chemical and radiative transfer modeling. While running UCLCHEMCMC, the created chemical models and radiative transfer code results are stored in an SQL database, preventing redundant model calculations in future inferences. This means that the more UCLCHEMCMC is used, the more efficient it becomes. Using UCLCHEM and RADEX, the increase of efficiency is nearly two orders of magnitude, going from 5185.33 \pm 1041.96 s for ten walkers to take one thousand steps when the database is empty, to 68.89 \pm 45.39 s when nearly all models requested are in the database. In order to demonstrate its usefulness we provide an example inference of UCLCHEMCMC to estimate the physical parameters of mock data, and perform two inferences on the well studied prestellar core, L1544, one of which show that it is important to consider the substructures of an object when determining which emission lines to use.Comment: 14 pages, 8 figures, 4 tables accepted by Ap

    Automatisierung des Bio-Plex Pro Analyseverfahrens

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    Für den simultanen Nachweis mehrerer Analyten innerhalb einer Probe ist die Bead-basierte Multiplexanalytik ein häufig verwendetes Verfahren und wird beispielsweise zur Quantifizierung von Proteinen genutzt. Die aufwendige Durchführung der Assays soll durch Automatisierung einerseits dem Anwender abgenommen werden, während andererseits die Genauigkeit und Reproduzierbarkeit der Analyse gesteigert wird. Die Automatisierung des Bio-Plex Pro™ Assays ist mit dem Pipettierroboter Tecan Freedom EVO 200 umgesetzt worden. Es ist ein Skript mit der Software Freedom EVOware® entwickelt worden, welches die Probenvorbereitung des Assays vollständig übernimmt. Für einen Vergleich der manuellen und automatisierten Methode sind die humanen Zytokine IL-2, IL-4, IL-10, GM-CSF, IFN-γ und TNF-α in einer achtstufigen Standardverdünnungsreihe und in unterschiedlich konzentrierten Proben gemessen worden. Die Berechnung der Streuungen (Standardabweichung und Variationskoeffizient) der einzelnen Standardverdünnungsreihen sowie der Vergleich von gemessenen und erwarteten Konzentrationen der automatisierten und manuellen Methode zeigen, dass die Automatisierung neben der zeitlichen Optimierung auch die Genauigkeit und Reproduzierbarkeit der Analyse verbessert.Bead-based multpiplex analysis is frequently used for the simultaneous detection of multiple analytes within a sample. Such assays are commonly used to quantify proteins. The automation of the process relieves the user from the complex assay conductance and on the other hand increases the accuracy and reproducibility of the analysis. The automation of the Bio-Plex Pro™ assay has been successfully implemented with the pipetting-robot Tecan Freedom EVO 200. A script has been developed, using the Freedom EVOware® which has the ability to perform the complete assay procedure. For a comparison between manual and automated methods, the human cytokines IL-2, IL-4, IL-10, GM-CSF, IFN-γ and TNF-α were analysed by an eight-point standard dilution series and with samples of different concentrations. The calculation of the variances (standard deviation and coefficient of variation) of the single standard dilution series as well as the comparison of the observed and expected concentrations of the manual or automated method show the higher precision and reproducibility of the automated process in addition to its time-saving nature

    Real-Time Gaze Tracking with a Consumer-Grade Video Camera

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    Eye gaze can be a rich source of information to identify particular interests of human users. Eye gaze tracking has been largely used in different research areas in the last years, as for example in psychology, visual system design and to leverage the user interaction with computer systems. In this paper, we present an IR-based gaze tracking framework that can be easily coupled to common user applications and allows for real-time gaze estimation. Compared to other gaze tracking systems, our system uses only affordable consumer-grade hardware and still achieves fair accuracy. To evaluate the usability of our gaze tracking system, we performed a user study with persons of different genders and ethnicities

    Changes in life expectancy 1950–2010: contributions from age- and disease-specific mortality in selected countries

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    BACKGROUND: Changes of life expectancy over time serve as an interesting public health indicator for medical, social and economic developments within populations. The aim of this study was to quantify changes of life expectancy between 1950 and 2010 and relate these to main causes of death. METHODS: Pollard’s actuarial method of decomposing life expectancy was applied to compare the contributions of different age- and disease-groups on life expectancy in 5-year intervals. RESULTS: From the 1960 to 70s on, declines in cardiovascular disease (CVD) mortality play an increasing role in improving life expectancy in many developed countries. During the past decades gains in life expectancy in these countries were mainly observed in age groups ≥65 years. A further consistent pattern was that life expectancy increases were stronger in men than in women, although life expectancy is still higher in women. In Japan, an accelerated epidemiologic transition in causes of death was found, with the highest increases between 1950 and 1955. Short-term declines and subsequent gains in life expectancy were observed in Eastern Europe and the former states of the Union of Soviet Socialist Republics (USSR), reflecting the changes of the political system. CONCLUSIONS: Changes of life years estimated with the decomposing method can be directly interpreted and may therefore be useful in public health communication. The development within specific countries is highly sensitive to changes in the political, social and public health environment. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s12963-016-0089-x) contains supplementary material, which is available to authorized users

    Prevalence of chronic urticaria in children and adults across the globe: Systematic review with meta‐analysis

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    Background and objectives: Urticaria is a frequent skin condition, but reliable prevalence estimates from population studies particularly of the chronic form are scarce. The objective of this study was to systematically evaluate and summarize the prevalence of chronic urticaria by evaluating population-based studies worldwide. Methods: We performed a systematic search in PUBMED and EMBASE for population-based studies of cross-sectional or cohort design and studies based on health insurance/system databases. Risk of bias was assessed using a specific tool for prevalence studies. For meta-analysis, we used a random effects model. Results: Eighteen studies were included in the systematic evaluation and 11 in the meta-analysis including data from over 86 000 000 participants. Risk of bias was mainly moderate, whereas the statistical heterogeneity (I-2) between the studies was high. Asian studies combined showed a higher point prevalence of chronic urticaria (1.4%, 95%-CI 0.5-2.9) than those from Europe (0.5%, 0.2-1.0) and Northern American (0.1%, 0.1-0.1). Women were slightly more affected than men, whereas in children < 15 years we did not find a sex-specific difference in the prevalence. The four studies that examined time trends indicated an increasing prevalence of chronic urticaria over time. Conclusions: On a global level, the prevalence of chronic urticaria showed considerable regional differences. There is a need to obtain more sex-specific population-based and standardized international data particularly for children and adolescents, different chronic urticaria subtypes and potential risk and protective factors

    Electron transfer rates for asymmetric reactions

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    We use a numerically exact real-time path integral Monte Carlo scheme to compute electron transfer dynamics between two redox sites within a spin-boson approach. The case of asymmetric reactions is studied in detail in the least understood crossover region between nonadiabatic and adiabatic electron transfer. At intermediate-to-high temperature, we find good agreement with standard Marcus theory, provided dynamical recrossing effects are captured. The agreement with our data is practically perfect when temperature renormalization is allowed. At low temperature we find peculiar electron transfer kinetics in strongly asymmetric systems, characterized by rapid transient dynamics and backflow to the donor.Comment: 13 pages, 4 figures, submitted to Chemical Physics Special Issue on the Spin-Boson Problem, ed. by H. Grabert and A. Nitza

    Kepler Flares II: The Temporal Morphology of White-Light Flares on GJ 1243

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    We present the largest sample of flares ever compiled for a single M dwarf, the active M4 star GJ 1243. Over 6100 individual flare events, with energies ranging from 102910^{29} to 103310^{33} erg, are found in 11 months of 1-minute cadence data from Kepler. This sample is unique for its completeness and dynamic range. We have developed automated tools for finding flares in short-cadence Kepler light curves, and performed extensive validation and classification of the sample by eye. From this pristine sample of flares we generate a median flare template. This template shows that two exponential cooling phases are present during the white-light flare decay, providing fundamental constraints for models of flare physics. The template is also used as a basis function to decompose complex multi-peaked flares, allowing us to study the energy distribution of these events. Only a small number of flare events are not well fit by our template. We find that complex, multi-peaked flares occur in over 80% of flares with a duration of 50 minutes or greater. The underlying distribution of flare durations for events 10 minutes and longer appears to follow a broken power law. Our results support the idea that sympathetic flaring may be responsible for some complex flare events.Comment: 12 pages, 9 figures, accepted for publication in Ap

    Shifting senses in lexical semantic development

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    Most words are associated with multiple senses. A DVD can be round (when describing a disc), and a DVD can be an hour long (when describing a movie), and in each case DVD means something different. The possible senses of a word are often predictable, and also constrained, as words cannot take just any meaning: for example, although a movie can be an hour long, it cannot sensibly be described as round (unlike a DVD). Learning the scope and limits of word meaning is vital for the comprehension of natural language, but poses a potentially difficult learnability problem for children. By testing what senses children are willing to assign to a variety of words, we demonstrate that, in comprehension, the problem is solved using a productive learning strategy. Children are perfectly capable of assigning different senses to a word; indeed they are essentially adult-like at assigning licensed meanings. But difficulties arise in determining which senses are assignable: children systematically overestimate the possible senses of a word, allowing meanings that adults rule unlicensed (e.g., taking round movie to refer to a disc). By contrast, this strategy does not extend to production, in which children use licensed, but not unlicensed, senses. Children’s productive comprehension strategy suggests an early emerging facility for using context in sense resolution (a difficult task for natural language processing algorithms), but leaves an intriguing question as to the mechanisms children use to learn a restricted, adult-like set of senses
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