651 research outputs found

    SOCR: Statistics Online Computational Resource

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    The need for hands-on computer laboratory experience in undergraduate and graduate statistics education has been firmly established in the past decade. As a result a number of attempts have been undertaken to develop novel approaches for problem-driven statistical thinking, data analysis and result interpretation. In this paper we describe an integrated educational web-based framework for: interactive distribution modeling, virtual online probability experimentation, statistical data analysis, visualization and integration. Following years of experience in statistical teaching at all college levels using established licensed statistical software packages, like STATA, S-PLUS, R, SPSS, SAS, Systat, etc., we have attempted to engineer a new statistics education environment, the Statistics Online Computational Resource (SOCR). This resource performs many of the standard types of statistical analysis, much like other classical tools. In addition, it is designed in a plug-in object-oriented architecture and is completely platform independent, web-based, interactive, extensible and secure. Over the past 4 years we have tested, fine-tuned and reanalyzed the SOCR framework in many of our undergraduate and graduate probability and statistics courses and have evidence that SOCR resources build student's intuition and enhance their learning.

    Patterns of Left Atrial Activation and Evaluation of Atrial Asynchrony in Patients with Atrial Fibrillation and Normal Controls: Factors beyond Left Atrial Dimensions

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    I. Extensive experimental and clinical data suggest that certain electrical and structural changes develop in the atria of patients with atrial fibrillation (AF). These alterations are commonly referred as atrial remodeling and are considered to play a crucial role in the self-perpetuation of this arrhythmia. a. A hallmark of LA structural remodeling is the LA dilatation which is a predictor for progression to chronic AF and therapeutic failure as well. However, AF is associated not only with LA enlargement but also with asymmetrical changes in the left atrial geometry. b. Furthermore, the electrical remodeling is characterized by slower and asynchronous inter- and intra-atrial conduction that also contributes to the maintenance of AF. Some studies suggested a role of the conduction block in the Bachmann’s bundle, connecting the right and left atrium, in the AF pathophysiology and LA remodeling. II. Echocardiography and especially the tissue Doppler method can provide additional insight into the nature of the LA remodeling, because it allows the characterization of the intrinsic LA velocities. a. Using pulsed-wave tissue Doppler (PW-TDI) is possible to measure the interval from the onset of the surface P wave to the A´ velocity at the lateral mitral annulus as a representation of the total interatrial conduction time (TACT). In number of studies, it was demonstrated that prolonged TACT was associated with new-onset AF, AF after open heart surgery, and AF recurrences after electrical cardioversion and catheter ablation. b. An important limitation of the previous studies is that TACT has never been validated by direct measurements of the true electrical conduction in the LA. Moreover, it was assumed that the activation of the lateral MA must be the latest LA activation site. III. In this study, we sought to evaluate the feasibility of the PW-TDI as a simple and quick method to evaluate the LA asynchrony. For the purpose, we measured the time intervals from the onset of P-wave to the A´ (P-A´) in PW-TDI at 4 different left atrial sites next to mitral annulus (septal, lateral, anterior and inferior) in patients referred for electrophysiological study and catheter ablation because of atrial fibrillation or other arrhythmias. a. The differences between the longest and shortest P-A´ (DLS-PA´), as well as the standard deviation (SD-4PA´) of all 4 values were calculated as indexes for LA asynchrony. Importantly, LA asynchrony in patients with AF was compared with a matched control group of patients without history of AF. b. Moreover, the TACT was validated by comparing it with the actual electrical activation of the left atrium measured directly in the coronary sinus. For this purpose, the intervals between the onset of the P-wave and the local LA activation at the distal electrode pair of a catheter inserted in the coronary sinus were measured. c. Having in mind the ovoid LA shape and asymmetrical changes in LA geometry observed in patients with AF, we hypothesized that the lateral mitral annulus may not always be the latest activation spot. Therefore, we sought to determine the latest LA activation site exhibiting the longest P-A´ interval, as well as to describe the sequence of LA activation in AF patients and non-AF controls. IV. One hundred and thirty patients with AF (AF group) and 70 patients without a history of AF (non-AF control group) were examined prospectively using PW-TDI. a. Both groups were matched for the baseline characteristics, including LA diameter. The P-A´ interval measured with PW-TDI at the lateral LA showed a strong, positive, linear correlation with the P-A activation at the distal poles of the CS catheter at the lateral MA: Pearson r=0.708; P=0.0001. b. Asynchrony in the AF group was more pronounced in comparison to the non-AF control group. Patients in the AF group had longer DLS-PA´ as compared to controls: 37±16 msec. vs. 28±13 msec.; P=0.0001, as well as bigger SD-4PA´: 17±7 msec. vs. 13±5 msec.; P=0.0001. c. Furthermore, distinct patterns of LA activation were observed. Most AF patients (86.5%) showed an upward LA activation with inferior LA breakthrough, whereas the non-AF controls exhibited mostly a downward LA activation (65.5%), spreading from LA roof downwards. d. ROC analysis revealed that P-A´ at anterior LA successfully discriminated patients with AF from the non-AF controls (AUC 0.85, P 55 msec. discriminated between AF patients and controls with 85% sensitivity; 81% specificity; positive predictive value of 0.898, and negative predictive value of 0.707. V. In conclusion, PW-TDI can be reliably used to assess the LA asynchrony. Patients with atrial fibrillation showed greater LA asynchrony in PW-TDI independently from the LA dimensions. For the first time, we described that LA activation showed 3 distinct patterns with the upward LA activation being the most frequently observed in patients with AF. Patients with AF demonstrated a prolonged P-A´ activation time at the anterior left atrium. P-A´ at anterior LA > 55 msec. discriminates between patients with AF and non-AF controls with high sensitivity and specificity. This method can be useful to identity patients at risk for occurrence of new-onset atrial fibrillation, as well as to assess the severity of the LA remodeling in order to improve the selection of patients for catheter ablation.:Table of Contents 1 Background 5 1.1 Mechanisms of initiation and perpetuation of atrial fibrillation 5 1.2 Left atrial remodeling in atrial fibrillation 7 1.3 Echocardiographic assessment of left atrial remodeling 8 1.4 Pathophysiology of interatrial conduction in atrial fibrillation 10 2 Objectives and methods 11 2.1 Study objectives 11 2.2 Methods 11 2.2.1 Echocardiography 13 2.2.2 Electrophysiological study 15 2.2.3 Statistical methods 16 3 Publication 17 4 Discussion 26 5 Limitations 30 6 Conclusion 31 7 Synopsis 32 8 References 36 9 Selbstständigkeitserklärung 47 10 Curriculum vitae and list of publications 48 11 Danksagung /Acknowledgments 5

    SOCR Analyses: Implementation and Demonstration of a New Graphical Statistics Educational Toolkit

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    The web-based, Java-written SOCR (Statistical Online Computational Resource) tools have been utilized in many undergraduate and graduate level statistics courses for seven years now (Dinov 2006; Dinov et al. 2008b). It has been proven that these resources can successfully improve students' learning (Dinov et al. 2008b). Being first published online in 2005, SOCR Analyses is a somewhat new component and it concentrate on data modeling for both parametric and non-parametric data analyses with graphical model diagnostics. One of the main purposes of SOCR Analyses is to facilitate statistical learning for high school and undergraduate students. As we have already implemented SOCR Distributions and Experiments, SOCR Analyses and Charts fulfill the rest of a standard statistics curricula. Currently, there are four core components of SOCR Analyses. Linear models included in SOCR Analyses are simple linear regression, multiple linear regression, one-way and two-way ANOVA. Tests for sample comparisons include t-test in the parametric category. Some examples of SOCR Analyses' in the non-parametric category are Wilcoxon rank sum test, Kruskal-Wallis test, Friedman's test, Kolmogorov-Smirnoff test and Fligner-Killeen test. Hypothesis testing models include contingency table, Friedman's test and Fisher's exact test. The last component of Analyses is a utility for computing sample sizes for normal distribution. In this article, we present the design framework, computational implementation and the utilization of SOCR Analyses.

    Methodological challenges and analytic opportunities for modeling and interpreting Big Healthcare Data

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    Abstract Managing, processing and understanding big healthcare data is challenging, costly and demanding. Without a robust fundamental theory for representation, analysis and inference, a roadmap for uniform handling and analyzing of such complex data remains elusive. In this article, we outline various big data challenges, opportunities, modeling methods and software techniques for blending complex healthcare data, advanced analytic tools, and distributed scientific computing. Using imaging, genetic and healthcare data we provide examples of processing heterogeneous datasets using distributed cloud services, automated and semi-automated classification techniques, and open-science protocols. Despite substantial advances, new innovative technologies need to be developed that enhance, scale and optimize the management and processing of large, complex and heterogeneous data. Stakeholder investments in data acquisition, research and development, computational infrastructure and education will be critical to realize the huge potential of big data, to reap the expected information benefits and to build lasting knowledge assets. Multi-faceted proprietary, open-source, and community developments will be essential to enable broad, reliable, sustainable and efficient data-driven discovery and analytics. Big data will affect every sector of the economy and their hallmark will be ‘team science’.http://deepblue.lib.umich.edu/bitstream/2027.42/134522/1/13742_2016_Article_117.pd

    THE FUNCTION OF ANALOGY IN PIANO PEDAGOGY

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    The paper explains the role played by the practice of analogical reasoning in piano lessons, especially at the beginner level. The first stage of piano studies is the most important one in raising musicians. In order to develop a young student’s understanding and appreciation of music and piano playing, teachers use interesting and logically connected stories with plenty of entertaining characters, colorful illustrations and imaginative scenes. Comprehensive analogies with images of characters and their adventures used to introduce and expand on musical concepts in working with beginners make complicated playing techniques understandable and acceptable to them. It is very important to invoke students’ imagination and creativity using fantasy, as well as analogies from everyday life, in order to help them to envisage musical images and express them through physical movements. By making progress in piano playing, students also improve their problem-solving skills in the arts, sciences, natural environment and social life

    Bochner Integrals and Vector Measures

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    This project extends known theorems for scalar valued functions to the context of Banach space valued functions. In particular, it contains generalizations of the classical theory of Lebesgue Integrals, complex measures, Radon-Nikodym theorem and Riesz Representation theorem. We explore some properties of functions whose domains are abstract Banach spaces, where the usual derivatives are replaced by Radon-Nikodym derivatives. The first two Chapters are devoted to infinite dimensional measurable functions and the problem of integrating them. Most of the basic properties of Bochner integration are forced on it by the classical Lebesgue integration and the usual definition of measurability. The Radon-Nikodym theorem for Bochner Integral is the subject to Chapter III. The roles of reflexive spaces, separable anti-dual spaces and the Radon-Nikodym property of Banach spaces are also discussed in this Chapter. One of the most interesting aspects of the theory of the Bochner integral centers about the following questions: When does a vector measure F: Ʒ→X arise as a Bochner integral of an L1(S,X) function (i.e. F(E) = ∫E f dm)? And conversely, if f ∈ L1(S,X). Then, is F: Ʒ→X, defined by F(E) = ∫E f dm, a countably additive vector measure, absolutely continuous with respect to the positive measure m? These two questiones are examined by the Radon-Nikodym theorem and the Riesz Representation theorem. It is worth observing, that the relationsip between these theorems are considered to be just a formality of translating a set of basic definitions from one context to another. There are theories of integration similar to the Bochner Integral, that allow us to integrate functions that are only weakly measurable (The Pettis Integral) with respect to a positive measure. Also, the ultimate generality of the Bochner Integral, the Bartle Integral, for integrating vector valued functions with respect to a general vector measure. However, these theories do not occupy a central role in our study and we limit ourselves to only mentioning [1] as an excellent reference

    Novel modeling of task versus rest brain state predictability using a dynamic time warping spectrum: comparisons and contrasts with other standard measures of brain dynamics

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    Dynamic time warping, or DTW, is a powerful and domain-general sequence alignment method for computing a similarity measure. Such dynamic programming-based techniques like DTW are now the backbone and driver of most bioinformatics methods and discoveries. In neuroscience it has had far less use, though this has begun to change. We wanted to explore new ways of applying DTW, not simply as a measure with which to cluster or compare similarity between features but in a conceptually different way. We have used DTW to provide a more interpretable spectral description of the data, compared to standard approaches such as the Fourier and related transforms. The DTW approach and standard discrete Fourier transform (DFT) are assessed against benchmark measures of neural dynamics. These include EEG microstates, EEG avalanches, and the sum squared error (SSE) from a multilayer perceptron (MLP) prediction of the EEG time series, and simultaneously acquired FMRI BOLD signal. We explored the relationships between these variables of interest in an EEG-FMRI dataset acquired during a standard cognitive task, which allowed us to explore how DTW differentially performs in different task settings. We found that despite strong correlations between DTW and DFT-spectra, DTW was a better predictor for almost every measure of brain dynamics. Using these DTW measures, we show that predictability is almost always higher in task than in rest states, which is consistent to other theoretical and empirical findings, providing additional evidence for the utility of the DTW approach

    PENGARUH VARIASI MEDIA PENDINGIN TERHADAP KEKERASAN DAN STRUKTUR MIKRO HASIL REMELTING Al-Si BERBASIS LIMBAH PISTON BEKAS DENGAN PERLAKUAN DEGASSING

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    The purpose of this study was (1) Determine the effect of the variation media cooling to hardness remelting of Al-Si based used piston waste with degassing treatment, (2) Determine the effect of the variation cooling media to micro structure remelting of Al-Si based used piston waste with degassing treatment, (3) Determine the effect of the optimal cooling media results hardness and micro structure remelting of Al-Si based used piston waste with degassing treatment.This study used an experimental method that uses a single independent variable factor (media cooling variation) and two-factor variable (hardness and microstructure). Objects in this study using the results of remelting of Al-Si piston former waste. Data analysis techniques in this study using descriptive data analysis results graphically illustrate the tables and histograms as well as images of micro structures. Input parameters in analyzing the data include: variations in the cooling medium (water well, oil SAE 40 and salt liquid), micro structure, and hardness.The results showed a change in the level of hardness and the micro structure formed. From the hardness test results obtained the highest level of hardness in the media cooling well water 86.83 BHN respectively towards the lows of the cooling medium salt liquid at 83.63 BHN, media SAE 40 oil cooler for 63.24 BHN, and the non-quenching at low 54.22 BHN. Microstructure test shows the micro structure consists of the formation of Al that is soft (low hardness) and Si as an addition to the level of hardness that affect resilience, the size of the grains of different suggesting that different levels of hardness coupled. So we get the greater amount Si then the resulting hardness will increase. Keywords: media cooling variation, Al-Si, hardness, micro structur

    SOCR Analyses: Implementation and Demonstration of a New Graphical Statistics Educational Toolkit

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    The web-based, Java-written SOCR (Statistical Online Computational Resource) toolshave been utilized in many undergraduate and graduate level statistics courses for sevenyears now (Dinov 2006; Dinov et al. 2008b). It has been proven that these resourcescan successfully improve students' learning (Dinov et al. 2008b). Being rst publishedonline in 2005, SOCR Analyses is a somewhat new component and it concentrate on datamodeling for both parametric and non-parametric data analyses with graphical modeldiagnostics. One of the main purposes of SOCR Analyses is to facilitate statistical learn-ing for high school and undergraduate students. As we have already implemented SOCRDistributions and Experiments, SOCR Analyses and Charts fulll the rest of a standardstatistics curricula. Currently, there are four core components of SOCR Analyses. Linearmodels included in SOCR Analyses are simple linear regression, multiple linear regression,one-way and two-way ANOVA. Tests for sample comparisons include t-test in the para-metric category. Some examples of SOCR Analyses' in the non-parametric category areWilcoxon rank sum test, Kruskal-Wallis test, Friedman's test, Kolmogorov-Smirno testand Fligner-Killeen test. Hypothesis testing models include contingency table, Friedman'stest and Fisher's exact test. The last component of Analyses is a utility for computingsample sizes for normal distribution. In this article, we present the design framework,computational implementation and the utilization of SOCR Analyses
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