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Sample records for stroke non-parametric statistics

  1. Using Mathematica to build Non-parametric Statistical Tables

    Directory of Open Access Journals (Sweden)

    Gloria Perez Sainz de Rozas

    2003-01-01

    Full Text Available In this paper, I present computational procedures to obtian statistical tables. The tables of the asymptotic distribution and the exact distribution of Kolmogorov-Smirnov statistic Dn for one population, the table of the distribution of the runs R, the table of the distribution of Wilcoxon signed-rank statistic W+ and the table of the distribution of Mann-Whitney statistic Ux using Mathematica, Version 3.9 under Window98. I think that it is an interesting cuestion because many statistical packages give the asymptotic significance level in the statistical tests and with these porcedures one can easily calculate the exact significance levels and the left-tail and right-tail probabilities with non-parametric distributions. I have used mathematica to make these calculations because one can use symbolic language to solve recursion relations. It's very easy to generate the format of the tables, and it's possible to obtain any table of the mentioned non-parametric distributions with any precision, not only with the standard parameters more used in Statistics, and without transcription mistakes. Furthermore, using similar procedures, we can generate tables for the following distribution functions: Binomial, Poisson, Hypergeometric, Normal, x2 Chi-Square, T-Student, F-Snedecor, Geometric, Gamma and Beta.

  2. Statistic Non-Parametric Methods of Measurement and Interpretation of Existing Statistic Connections within Seaside Hydro Tourism

    OpenAIRE

    Mirela Secară

    2008-01-01

    Tourism represents an important field of economic and social life in our country, and the main sector of the economy of Constanta County is the balneary touristic capitalization of Romanian seaside. In order to statistically analyze hydro tourism on Romanian seaside, we have applied non-parametric methods of measuring and interpretation of existing statistic connections within seaside hydro tourism. Major objective of this research is represented by hydro tourism re-establishment on Romanian ...

  3. The application of non-parametric statistical method for an ALARA implementation

    International Nuclear Information System (INIS)

    Cho, Young Ho; Herr, Young Hoi

    2003-01-01

    The cost-effective reduction of Occupational Radiation Dose (ORD) at a nuclear power plant could not be achieved without going through an extensive analysis of accumulated ORD data of existing plants. Through the data analysis, it is required to identify what are the jobs of repetitive high ORD at the nuclear power plant. In this study, Percentile Rank Sum Method (PRSM) is proposed to identify repetitive high ORD jobs, which is based on non-parametric statistical theory. As a case study, the method is applied to ORD data of maintenance and repair jobs at Kori units 3 and 4 that are pressurized water reactors with 950 MWe capacity and have been operated since 1986 and 1987, respectively in Korea. The results was verified and validated, and PRSM has been demonstrated to be an efficient method of analyzing the data

  4. A force profile analysis comparison between functional data analysis, statistical parametric mapping and statistical non-parametric mapping in on-water single sculling.

    Science.gov (United States)

    Warmenhoven, John; Harrison, Andrew; Robinson, Mark A; Vanrenterghem, Jos; Bargary, Norma; Smith, Richard; Cobley, Stephen; Draper, Conny; Donnelly, Cyril; Pataky, Todd

    2018-03-21

    To examine whether the Functional Data Analysis (FDA), Statistical Parametric Mapping (SPM) and Statistical non-Parametric Mapping (SnPM) hypothesis testing techniques differ in their ability to draw inferences in the context of a single, simple experimental design. The sample data used is cross-sectional (two-sample gender comparison) and evaluation of differences between statistical techniques used a combination of descriptive and qualitative assessments. FDA, SPM and SnPM t-tests were applied to sample data of twenty highly skilled male and female rowers, rowing at 32 strokes per minute in a single scull boat. Statistical differences for gender were assessed by applying two t-tests (one for each side of the boat). The t-statistic values were identical for all three methods (with the FDA t-statistic presented as an absolute measure). The critical t-statistics (t crit ) were very similar between the techniques, with SPM t crit providing a marginally higher t crit than the FDA and SnPM t crit values (which were identical). All techniques were successful in identifying consistent sections of the force waveform, where male and female rowers were shown to differ significantly (pparametric assumption of SPM, as well as contextual factors related to the type of waveform data to be analysed and the experimental research question of interest. Copyright © 2018. Published by Elsevier Ltd.

  5. Non-parametric order statistics method applied to uncertainty propagation in fuel rod calculations

    International Nuclear Information System (INIS)

    Arimescu, V.E.; Heins, L.

    2001-01-01

    Advances in modeling fuel rod behavior and accumulations of adequate experimental data have made possible the introduction of quantitative methods to estimate the uncertainty of predictions made with best-estimate fuel rod codes. The uncertainty range of the input variables is characterized by a truncated distribution which is typically a normal, lognormal, or uniform distribution. While the distribution for fabrication parameters is defined to cover the design or fabrication tolerances, the distribution of modeling parameters is inferred from the experimental database consisting of separate effects tests and global tests. The final step of the methodology uses a Monte Carlo type of random sampling of all relevant input variables and performs best-estimate code calculations to propagate these uncertainties in order to evaluate the uncertainty range of outputs of interest for design analysis, such as internal rod pressure and fuel centerline temperature. The statistical method underlying this Monte Carlo sampling is non-parametric order statistics, which is perfectly suited to evaluate quantiles of populations with unknown distribution. The application of this method is straightforward in the case of one single fuel rod, when a 95/95 statement is applicable: 'with a probability of 95% and confidence level of 95% the values of output of interest are below a certain value'. Therefore, the 0.95-quantile is estimated for the distribution of all possible values of one fuel rod with a statistical confidence of 95%. On the other hand, a more elaborate procedure is required if all the fuel rods in the core are being analyzed. In this case, the aim is to evaluate the following global statement: with 95% confidence level, the expected number of fuel rods which are not exceeding a certain value is all the fuel rods in the core except only a few fuel rods. In both cases, the thresholds determined by the analysis should be below the safety acceptable design limit. An indirect

  6. Speeding Up Non-Parametric Bootstrap Computations for Statistics Based on Sample Moments in Small/Moderate Sample Size Applications.

    Science.gov (United States)

    Chaibub Neto, Elias

    2015-01-01

    In this paper we propose a vectorized implementation of the non-parametric bootstrap for statistics based on sample moments. Basically, we adopt the multinomial sampling formulation of the non-parametric bootstrap, and compute bootstrap replications of sample moment statistics by simply weighting the observed data according to multinomial counts instead of evaluating the statistic on a resampled version of the observed data. Using this formulation we can generate a matrix of bootstrap weights and compute the entire vector of bootstrap replications with a few matrix multiplications. Vectorization is particularly important for matrix-oriented programming languages such as R, where matrix/vector calculations tend to be faster than scalar operations implemented in a loop. We illustrate the application of the vectorized implementation in real and simulated data sets, when bootstrapping Pearson's sample correlation coefficient, and compared its performance against two state-of-the-art R implementations of the non-parametric bootstrap, as well as a straightforward one based on a for loop. Our investigations spanned varying sample sizes and number of bootstrap replications. The vectorized bootstrap compared favorably against the state-of-the-art implementations in all cases tested, and was remarkably/considerably faster for small/moderate sample sizes. The same results were observed in the comparison with the straightforward implementation, except for large sample sizes, where the vectorized bootstrap was slightly slower than the straightforward implementation due to increased time expenditures in the generation of weight matrices via multinomial sampling.

  7. Performances of non-parametric statistics in sensitivity analysis and parameter ranking

    International Nuclear Information System (INIS)

    Saltelli, A.

    1987-01-01

    Twelve parametric and non-parametric sensitivity analysis techniques are compared in the case of non-linear model responses. The test models used are taken from the long-term risk analysis for the disposal of high level radioactive waste in a geological formation. They describe the transport of radionuclides through a set of engineered and natural barriers from the repository to the biosphere and to man. The output data from these models are the dose rates affecting the maximum exposed individual of a critical group at a given point in time. All the techniques are applied to the output from the same Monte Carlo simulations, where a modified version of Latin Hypercube method is used for the sample selection. Hypothesis testing is systematically applied to quantify the degree of confidence in the results given by the various sensitivity estimators. The estimators are ranked according to their robustness and stability, on the basis of two test cases. The conclusions are that no estimator can be considered the best from all points of view and recommend the use of more than just one estimator in sensitivity analysis

  8. Inferential, non-parametric statistics to assess the quality of probabilistic forecast systems

    NARCIS (Netherlands)

    Maia, A.H.N.; Meinke, H.B.; Lennox, S.; Stone, R.C.

    2007-01-01

    Many statistical forecast systems are available to interested users. To be useful for decision making, these systems must be based on evidence of underlying mechanisms. Once causal connections between the mechanism and its statistical manifestation have been firmly established, the forecasts must

  9. Technical Topic 3.2.2.d Bayesian and Non-Parametric Statistics: Integration of Neural Networks with Bayesian Networks for Data Fusion and Predictive Modeling

    Science.gov (United States)

    2016-05-31

    Distribution Unlimited UU UU UU UU 31-05-2016 15-Apr-2014 14-Jan-2015 Final Report: Technical Topic 3.2.2.d Bayesian and Non- parametric Statistics...of Papers published in non peer-reviewed journals: Final Report: Technical Topic 3.2.2.d Bayesian and Non- parametric Statistics: Integration of Neural...Transfer N/A Number of graduating undergraduates who achieved a 3.5 GPA to 4.0 (4.0 max scale ): Number of graduating undergraduates funded by a DoD funded

  10. When the Single Matters more than the Group (II): Addressing the Problem of High False Positive Rates in Single Case Voxel Based Morphometry Using Non-parametric Statistics.

    Science.gov (United States)

    Scarpazza, Cristina; Nichols, Thomas E; Seramondi, Donato; Maumet, Camille; Sartori, Giuseppe; Mechelli, Andrea

    2016-01-01

    In recent years, an increasing number of studies have used Voxel Based Morphometry (VBM) to compare a single patient with a psychiatric or neurological condition of interest against a group of healthy controls. However, the validity of this approach critically relies on the assumption that the single patient is drawn from a hypothetical population with a normal distribution and variance equal to that of the control group. In a previous investigation, we demonstrated that family-wise false positive error rate (i.e., the proportion of statistical comparisons yielding at least one false positive) in single case VBM are much higher than expected (Scarpazza et al., 2013). Here, we examine whether the use of non-parametric statistics, which does not rely on the assumptions of normal distribution and equal variance, would enable the investigation of single subjects with good control of false positive risk. We empirically estimated false positive rates (FPRs) in single case non-parametric VBM, by performing 400 statistical comparisons between a single disease-free individual and a group of 100 disease-free controls. The impact of smoothing (4, 8, and 12 mm) and type of pre-processing (Modulated, Unmodulated) was also examined, as these factors have been found to influence FPRs in previous investigations using parametric statistics. The 400 statistical comparisons were repeated using two independent, freely available data sets in order to maximize the generalizability of the results. We found that the family-wise error rate was 5% for increases and 3.6% for decreases in one data set; and 5.6% for increases and 6.3% for decreases in the other data set (5% nominal). Further, these results were not dependent on the level of smoothing and modulation. Therefore, the present study provides empirical evidence that single case VBM studies with non-parametric statistics are not susceptible to high false positive rates. The critical implication of this finding is that VBM can be used

  11. Piezoelectric sensing and non-parametric statistical signal processing for health monitoring of hysteretic dampers used in seismic-resistant structures

    Science.gov (United States)

    Gallego, A.; Benavent-Climent, A.; Romo-Melo, L.

    2015-08-01

    The paper proposes a new application of non-parametric statistical processing of signals recorded from vibration tests for damage detection and evaluation on I-section steel segments. The steel segments investigated constitute the energy dissipating part of a new type of hysteretic damper that is used for passive control of buildings and civil engineering structures subjected to earthquake-type dynamic loadings. Two I-section steel segments with different levels of damage were instrumented with piezoceramic sensors and subjected to controlled white noise random vibrations. The signals recorded during the tests were processed using two non-parametric methods (the power spectral density method and the frequency response function method) that had never previously been applied to hysteretic dampers. The appropriateness of these methods for quantifying the level of damage on the I-shape steel segments is validated experimentally. Based on the results of the random vibrations, the paper proposes a new index that predicts the level of damage and the proximity of failure of the hysteretic damper.

  12. Heart Disease and Stroke Statistics

    Science.gov (United States)

    ... mortality statistics found in the Heart Disease & Stroke Statistics Update . Because mortality is considered "hard" data, it's possible to do time-trend analysis and compute percent changes over time. What are ...

  13. Analysis of long term meteorological trends in the middle and lower Indus Basin of Pakistan-A non-parametric statistical approach

    Science.gov (United States)

    Ahmad, Waqas; Fatima, Aamira; Awan, Usman Khalid; Anwar, Arif

    2014-11-01

    The Indus basin of Pakistan is vulnerable to climate change which would directly affect the livelihoods of poor people engaged in irrigated agriculture. The situation could be worse in middle and lower part of this basin which occupies 90% of the irrigated area. The objective of this research is to analyze the long term meteorological trends in the middle and lower parts of Indus basin of Pakistan. We used monthly data from 1971 to 2010 and applied non-parametric seasonal Kendal test for trend detection in combination with seasonal Kendall slope estimator to quantify the magnitude of trends. The meteorological parameters considered were mean maximum and mean minimum air temperature, and rainfall from 12 meteorological stations located in the study region. We examined the reliability and spatial integrity of data by mass-curve analysis and spatial correlation matrices, respectively. Analysis was performed for four seasons (spring-March to May, summer-June to August, fall-September to November and winter-December to February). The results show that max. temperature has an average increasing trend of magnitude + 0.16, + 0.03, 0.0 and + 0.04 °C/decade during all the four seasons, respectively. The average trend of min. temperature during the four seasons also increases with magnitude of + 0.29, + 0.12, + 0.36 and + 0.36 °C/decade, respectively. Persistence of the increasing trend is more pronounced in the min. temperature as compared to the max. temperature on annual basis. Analysis of rainfall data has not shown any noteworthy trend during winter, fall and on annual basis. However during spring and summer season, the rainfall trends vary from - 1.15 to + 0.93 and - 3.86 to + 2.46 mm/decade, respectively. It is further revealed that rainfall trends during all seasons are statistically non-significant. Overall the study area is under a significant warming trend with no changes in rainfall.

  14. Stochastic Non-Parametric Frontier Analysis

    OpenAIRE

    Mohammad Rahmani; Gholamreza Jahanshahloo

    2014-01-01

    In this paper we develop an approach that synthesizes the best features of the two main methods in the estimation of production eciency. Specically, our approach rst allows for statistical noise, similar to Stochastic frontier analysis , and second, it allows modeling multiple-inputs-multiple-outputs technologies without imposing parametric assumptions on production relationship, similar to what is done in non-parametric methods. The methodology is based on the theory of local maximum likelih...

  15. Stochastic Non-Parametric Frontier Analysis

    Directory of Open Access Journals (Sweden)

    Mohammad Rahmani

    2014-05-01

    Full Text Available In this paper we develop an approach that synthesizes the best features of the two main methods in the estimation of production eciency. Specically, our approach rst allows for statistical noise, similar to Stochastic frontier analysis , and second, it allows modeling multiple-inputs-multiple-outputs technologies without imposing parametric assumptions on production relationship, similar to what is done in non-parametric methods. The methodology is based on the theory of local maximum likelihood estimation and extends recent works of Kumbhakar et al. We will use local-spherical coordinate system to transform multi-input multi-output data to more exible system which we can use in our approach. We also illustrate the performance of our approach with simulated example

  16. Estimation of the limit of detection with a bootstrap-derived standard error by a partly non-parametric approach. Application to HPLC drug assays

    DEFF Research Database (Denmark)

    Linnet, Kristian

    2005-01-01

    Bootstrap, HPLC, limit of blank, limit of detection, non-parametric statistics, type I and II errors......Bootstrap, HPLC, limit of blank, limit of detection, non-parametric statistics, type I and II errors...

  17. Bayesian non parametric modelling of Higgs pair production

    Directory of Open Access Journals (Sweden)

    Scarpa Bruno

    2017-01-01

    Full Text Available Statistical classification models are commonly used to separate a signal from a background. In this talk we face the problem of isolating the signal of Higgs pair production using the decay channel in which each boson decays into a pair of b-quarks. Typically in this context non parametric methods are used, such as Random Forests or different types of boosting tools. We remain in the same non-parametric framework, but we propose to face the problem following a Bayesian approach. A Dirichlet process is used as prior for the random effects in a logit model which is fitted by leveraging the Polya-Gamma data augmentation. Refinements of the model include the insertion in the simple model of P-splines to relate explanatory variables with the response and the use of Bayesian trees (BART to describe the atoms in the Dirichlet process.

  18. Comparação de duas metodologias de amostragem atmosférica com ferramenta estatística não paramétrica Comparison of two atmospheric sampling methodologies with non-parametric statistical tools

    Directory of Open Access Journals (Sweden)

    Maria João Nunes

    2005-03-01

    Full Text Available In atmospheric aerosol sampling, it is inevitable that the air that carries particles is in motion, as a result of both externally driven wind and the sucking action of the sampler itself. High or low air flow sampling speeds may lead to significant particle size bias. The objective of this work is the validation of measurements enabling the comparison of species concentration from both air flow sampling techniques. The presence of several outliers and increase of residuals with concentration becomes obvious, requiring non-parametric methods, recommended for the handling of data which may not be normally distributed. This way, conversion factors are obtained for each of the various species under study using Kendall regression.

  19. Non-Parametric Estimation of Correlation Functions

    DEFF Research Database (Denmark)

    Brincker, Rune; Rytter, Anders; Krenk, Steen

    In this paper three methods of non-parametric correlation function estimation are reviewed and evaluated: the direct method, estimation by the Fast Fourier Transform and finally estimation by the Random Decrement technique. The basic ideas of the techniques are reviewed, sources of bias are point...... out, and methods to prevent bias are presented. The techniques are evaluated by comparing their speed and accuracy on the simple case of estimating auto-correlation functions for the response of a single degree-of-freedom system loaded with white noise....

  20. On Parametric (and Non-Parametric Variation

    Directory of Open Access Journals (Sweden)

    Neil Smith

    2009-11-01

    Full Text Available This article raises the issue of the correct characterization of ‘Parametric Variation’ in syntax and phonology. After specifying their theoretical commitments, the authors outline the relevant parts of the Principles–and–Parameters framework, and draw a three-way distinction among Universal Principles, Parameters, and Accidents. The core of the contribution then consists of an attempt to provide identity criteria for parametric, as opposed to non-parametric, variation. Parametric choices must be antecedently known, and it is suggested that they must also satisfy seven individually necessary and jointly sufficient criteria. These are that they be cognitively represented, systematic, dependent on the input, deterministic, discrete, mutually exclusive, and irreversible.

  1. Non-parametric correlative uncertainty quantification and sensitivity analysis: Application to a Langmuir bimolecular adsorption model

    Directory of Open Access Journals (Sweden)

    Jinchao Feng

    2018-03-01

    Full Text Available We propose non-parametric methods for both local and global sensitivity analysis of chemical reaction models with correlated parameter dependencies. The developed mathematical and statistical tools are applied to a benchmark Langmuir competitive adsorption model on a close packed platinum surface, whose parameters, estimated from quantum-scale computations, are correlated and are limited in size (small data. The proposed mathematical methodology employs gradient-based methods to compute sensitivity indices. We observe that ranking influential parameters depends critically on whether or not correlations between parameters are taken into account. The impact of uncertainty in the correlation and the necessity of the proposed non-parametric perspective are demonstrated.

  2. Non-parametric correlative uncertainty quantification and sensitivity analysis: Application to a Langmuir bimolecular adsorption model

    Science.gov (United States)

    Feng, Jinchao; Lansford, Joshua; Mironenko, Alexander; Pourkargar, Davood Babaei; Vlachos, Dionisios G.; Katsoulakis, Markos A.

    2018-03-01

    We propose non-parametric methods for both local and global sensitivity analysis of chemical reaction models with correlated parameter dependencies. The developed mathematical and statistical tools are applied to a benchmark Langmuir competitive adsorption model on a close packed platinum surface, whose parameters, estimated from quantum-scale computations, are correlated and are limited in size (small data). The proposed mathematical methodology employs gradient-based methods to compute sensitivity indices. We observe that ranking influential parameters depends critically on whether or not correlations between parameters are taken into account. The impact of uncertainty in the correlation and the necessity of the proposed non-parametric perspective are demonstrated.

  3. Non-parametric approach to the study of phenotypic stability.

    Science.gov (United States)

    Ferreira, D F; Fernandes, S B; Bruzi, A T; Ramalho, M A P

    2016-02-19

    The aim of this study was to undertake the theoretical derivations of non-parametric methods, which use linear regressions based on rank order, for stability analyses. These methods were extension different parametric methods used for stability analyses and the result was compared with a standard non-parametric method. Intensive computational methods (e.g., bootstrap and permutation) were applied, and data from the plant-breeding program of the Biology Department of UFLA (Minas Gerais, Brazil) were used to illustrate and compare the tests. The non-parametric stability methods were effective for the evaluation of phenotypic stability. In the presence of variance heterogeneity, the non-parametric methods exhibited greater power of discrimination when determining the phenotypic stability of genotypes.

  4. Speaker Linking and Applications using Non-Parametric Hashing Methods

    Science.gov (United States)

    2016-09-08

    Speaker Linking and Applications using Non-Parametric Hashing Methods† Douglas Sturim and William M. Campbell MIT Lincoln Laboratory, Lexington, MA...to prove this by extending the proof of [8] to non-parametric hashing. 6. References [1] W. M. Campbell, D. E. Sturim, and D. A. Reynolds , “Support vec...EPFL-CONF-192414, 2012. [13] S. H. Shum, W. M. Campbell, and D. A. Reynolds , “Large-scale community detection on speaker content graphs,” in

  5. Non-Parametric Statistical Software for the TRS-80 Microcomputer.

    Science.gov (United States)

    1982-12-01

    Louisville, 1971 Submitted in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE IN APPLIED SCIENCE from the NAVAL POSTGRADUATE...for the iterative solution is T<’---Test Stastistic Denominator <--- 1 Do Until ABS(Tdenom - Denominator) ’ .0001 D <--- T/Denominator S <--- D*(.35...34 : PRINT TAB(17) "requirements for the degree of" 80 PRINT : PRINT TAB(19) "MASTER OF APPLIED SCIENCE" 90 PRINT : PRINT TAB(28) "from the" 100 PRINT

  6. Measuring the Influence of Information Networks on Transaction Costs Using a Non-parametric Regression Technique

    DEFF Research Database (Denmark)

    Henningsen, Geraldine; Henningsen, Arne; Henning, Christian

    2011-01-01

    All business transactions as well as achieving innovations take up resources, subsumed under the concept of transaction costs (TAC). One of the major factors in TAC theory is information. Information networks can catalyse the interpersonal information exchange and hence, increase the access to no...... are unveiled by reduced productivity. A cross-validated local linear non-parametric regression shows that good information networks increase the productivity of farms. A bootstrapping procedure confirms that this result is statistically significant....

  7. Assessing non-inferiority with time-to-event data via the method of non-parametric covariance.

    Science.gov (United States)

    Zhang, Xinji; Xu, Jinfang; He, Jia

    2013-06-01

    Non-parametric methods have been well recognised as useful tools for time-to-event (survival) data analysis because they provide valid statistical inference with few assumptions. Tangen and Koch have proposed the use of the method of non-parametric covariance for time-to-event data in a traditional superiority setting. In this article, we extended their method to assess non-inferiority of two treatments. To evaluate this non-parametric method versus the classical semi-parametric Cox proportional hazards regression model, simulations in terms of the Type 1 error rate and power were performed and compared. The results showed that the two methods were generally comparable regarding the Type 1 error rate when adjustment for the covariates correlated with the survival time was made. In the non-inferiority setting, the covariate-adjusted non-parametric analysis was shown to always increase power. However, this was not necessarily the case for the adjusted Cox model where results were inconsistent to those seen in the superiority setting. For illustration, an application of the proposed non-parametric method to a trial involving pemetrexed, a recently approved drug for first-line treatment of non-small cell lung cancer, is included.

  8. Use of parametric and non-parametric survival analysis techniques ...

    African Journals Online (AJOL)

    This paper presents parametric and non-parametric survival analysis procedures that can be used to compare acaricides. The effectiveness of Delta Tick Pour On and Delta Tick Spray in knocking down tsetse flies were determined. The two formulations were supplied by Chemplex. The comparison was based on data ...

  9. Non-Parametric Analysis of Rating Transition and Default Data

    DEFF Research Database (Denmark)

    Fledelius, Peter; Lando, David; Perch Nielsen, Jens

    2004-01-01

    We demonstrate the use of non-parametric intensity estimation - including construction of pointwise confidence sets - for analyzing rating transition data. We find that transition intensities away from the class studied here for illustration strongly depend on the direction of the previous move b...

  10. Meta-analysis of candidate gene effects using bayesian parametric and non-parametric approaches.

    Science.gov (United States)

    Wu, Xiao-Lin; Gianola, Daniel; Rosa, Guilherme J M; Weigel, Kent A

    2014-01-01

    Candidate gene (CG) approaches provide a strategy for identification and characterization of major genes underlying complex phenotypes such as production traits and susceptibility to diseases, but the conclusions tend to be inconsistent across individual studies. Meta-analysis approaches can deal with these situations, e.g., by pooling effect-size estimates or combining P values from multiple studies. In this paper, we evaluated the performance of two types of statistical models, parametric and non-parametric, for meta-analysis of CG effects using simulated data. Both models estimated a "central" effect size while taking into account heterogeneity over individual studies. The empirical distribution of study-specific CG effects was multi-modal. The parametric model assumed a normal distribution for the study-specific CG effects whereas the non-parametric model relaxed this assumption by posing a more general distribution with a Dirichlet process prior (DPP). Results indicated that the meta-analysis approaches could reduce false positive or false negative rates by pooling strengths from multiple studies, as compared to individual studies. In addition, the non-parametric, DPP model captured the variation of the "data" better than its parametric counterpart.

  11. Using non-parametric methods in econometric production analysis

    DEFF Research Database (Denmark)

    Czekaj, Tomasz Gerard; Henningsen, Arne

    2012-01-01

    by investigating the relationship between the elasticity of scale and the farm size. We use a balanced panel data set of 371~specialised crop farms for the years 2004-2007. A non-parametric specification test shows that neither the Cobb-Douglas function nor the Translog function are consistent with the "true......Econometric estimation of production functions is one of the most common methods in applied economic production analysis. These studies usually apply parametric estimation techniques, which obligate the researcher to specify a functional form of the production function of which the Cobb...... parameter estimates, but also in biased measures which are derived from the parameters, such as elasticities. Therefore, we propose to use non-parametric econometric methods. First, these can be applied to verify the functional form used in parametric production analysis. Second, they can be directly used...

  12. Non-parametric versus parametric methods in environmental sciences

    Directory of Open Access Journals (Sweden)

    Muhammad Riaz

    2017-06-01

    Full Text Available This current report intends to highlight the importance of considering background assumptions required for the analysis of real datasets in different disciplines. We will provide comparative discussion of parametric methods (that depends on distributional assumptions (like normality relative to non-parametric methods (that are free from many distributional assumptions. We have chosen a real dataset from environmental sciences (one of the application areas. The findings may be extended to the other disciplines following the same spirit.

  13. Digital spectral analysis parametric, non-parametric and advanced methods

    CERN Document Server

    Castanié, Francis

    2013-01-01

    Digital Spectral Analysis provides a single source that offers complete coverage of the spectral analysis domain. This self-contained work includes details on advanced topics that are usually presented in scattered sources throughout the literature.The theoretical principles necessary for the understanding of spectral analysis are discussed in the first four chapters: fundamentals, digital signal processing, estimation in spectral analysis, and time-series models.An entire chapter is devoted to the non-parametric methods most widely used in industry.High resolution methods a

  14. Reducing the false positive rate in the non-parametric analysis of molecular coevolution

    Directory of Open Access Journals (Sweden)

    O'Dea Shirley

    2008-04-01

    Full Text Available Abstract Background The strength of selective constraints operating on amino acid sites of proteins has a multifactorial nature. In fact, amino acid sites within proteins coevolve due to their functional and/or structural relationships. Different methods have been developed that attempt to account for the evolutionary dependencies between amino acid sites. Researchers have invested a significant effort to increase the sensitivity of such methods. However, the difficulty in disentangling functional co-dependencies from historical covariation has fuelled the scepticism over their power to detect biologically meaningful results. In addition, the biological parameters connecting linear sequence evolution to structure evolution remain elusive. For these reasons, most of the evolutionary studies aimed at identifying functional dependencies among protein domains have focused on the structural properties of proteins rather than on the information extracted from linear multiple sequence alignments (MSA. Non-parametric methods to detect coevolution have been reported to be especially susceptible to produce false positive results based on the properties of MSAs. However, no formal statistical analysis has been performed to definitively test the differential effects of these properties on the sensitivity of such methods. Results Here we test the effect that variations on the MSA properties have over the sensitivity of non-parametric methods to detect coevolution. We test the effect that the size of the MSA (number of sequences, mean pairwise amino acid distance per site and the strength of the coevolution signal have on the ability of non-parametric methods to detect coevolution. Our results indicate that all three factors have significant effects on the accuracy of non-parametric methods. Further, introducing statistical filters improves the sensitivity and increases the statistical power of the methods to detect functional coevolution. Statistical

  15. Effect of the 1973 oil price embargo; A non-parametric analysis

    Energy Technology Data Exchange (ETDEWEB)

    Goel, R.K.; Morey, M.J. (Illinois State Univ., Normal, IL (United States). Dept. of Economics)

    1993-01-01

    This paper focuses on the effect of the oil shock of 1973 on US gasoline demand by examining the price elasticities of demand before and after the 1973 embargo. Price elasticities provide useful input to the development of public policy dealing with taxation and pollution control. The extensive data used include state level observations for nearly three decades spanning 1952-80. We apply non-parametric regression methods that are more appropriate to our investigation than traditional parametric techniques. Unlike standard regression techniques, non-parametric methods neither assume a functional form for the demand relation nor restrict the distribution of the dependent variable. Our results show that the mean price elasticity of gasoline demand for the USA was - 0.243 for 1952-73 and the corresponding number for 1973-80 was - 0.576, statistically different at the 5% level of significance. The relatively higher price elasticity in the post-embargo period is consistent with the hypothesis that consumers sought substitutes and restricted their consumption in response to prices as well as social responsibility. The policy implications of these results are also discussed. (author)

  16. Debt and growth: A non-parametric approach

    Science.gov (United States)

    Brida, Juan Gabriel; Gómez, David Matesanz; Seijas, Maria Nela

    2017-11-01

    In this study, we explore the dynamic relationship between public debt and economic growth by using a non-parametric approach based on data symbolization and clustering methods. The study uses annual data of general government consolidated gross debt-to-GDP ratio and gross domestic product for sixteen countries between 1977 and 2015. Using symbolic sequences, we introduce a notion of distance between the dynamical paths of different countries. Then, a Minimal Spanning Tree and a Hierarchical Tree are constructed from time series to help detecting the existence of groups of countries sharing similar economic performance. The main finding of the study appears for the period 2008-2016 when several countries surpassed the 90% debt-to-GDP threshold. During this period, three groups (clubs) of countries are obtained: high, mid and low indebted countries, suggesting that the employed debt-to-GDP threshold drives economic dynamics for the selected countries.

  17. Multi-Directional Non-Parametric Analysis of Agricultural Efficiency

    DEFF Research Database (Denmark)

    Balezentis, Tomas

    This thesis seeks to develop methodologies for assessment of agricultural efficiency and employ them to Lithuanian family farms. In particular, we focus on three particular objectives throughout the research: (i) to perform a fully non-parametric analysis of efficiency effects, (ii) to extend...... to the Multi-Directional Efficiency Analysis approach when the proposed models were employed to analyse empirical data of Lithuanian family farm performance, we saw substantial differences in efficiencies associated with different inputs. In particular, assets appeared to be the least efficiently used input...... relative to labour, intermediate consumption and land (in some cases land was not treated as a discretionary input). These findings call for further research on relationships among financial structure, investment decisions, and efficiency in Lithuanian family farms. Application of different techniques...

  18. Statistical evaluation of adding multiple risk factors improves Framingham stroke risk score.

    Science.gov (United States)

    Zhou, Xiao-Hua; Wang, Xiaonan; Duncan, Ashlee; Hu, Guizhou; Zheng, Jiayin

    2017-04-14

    Framingham Stroke Risk Score (FSRS) is the most well-regarded risk appraisal tools for evaluating an individual's absolute risk on stroke onset. However, several widely accepted risk factors for stroke were not included in the original Framingham model. This study proposed a new model which combines an existing risk models with new risk factors using synthesis analysis, and applied it to the longitudinal Atherosclerosis Risk in Communities (ARIC) data set. Risk factors in original prediction models and new risk factors in proposed model had been discussed. Three measures, like discrimination, calibration and reclassification, were used to evaluate the performance of the original Framingham model and new risk prediction model. Modified C-statistics, Hosmer-Lemeshow Test and classless NRI, class NRI were the statistical indices which, respectively, denoted the performance of discrimination, calibration and reclassification for evaluating the newly developed risk prediction model on stroke onset. It showed that the NEW-STROKE (new stroke risk score prediction model) model had higher modified C-statistics, smaller Hosmer-Lemeshow chi-square values after recalibration than original FSRS model, and the classless NRI and class NRI of the NEW-STROKE model over the original FSRS model were all significantly positive in overall group. The NEW-STROKE integrated with seven literature-derived risk factors outperformed the original FSRS model in predicting the risk score of stroke. It illustrated that seven literature-derived risk factors contributed significantly to stroke risk prediction.

  19. Parametric and non-parametric approach for sensory RATA (Rate-All-That-Apply) method of ledre profile attributes

    Science.gov (United States)

    Hastuti, S.; Harijono; Murtini, E. S.; Fibrianto, K.

    2018-03-01

    This current study is aimed to investigate the use of parametric and non-parametric approach for sensory RATA (Rate-All-That-Apply) method. Ledre as Bojonegoro unique local food product was used as point of interest, in which 319 panelists were involved in the study. The result showed that ledre is characterized as easy-crushed texture, sticky in mouth, stingy sensation and easy to swallow. It has also strong banana flavour with brown in colour. Compared to eggroll and semprong, ledre has more variances in terms of taste as well the roll length. As RATA questionnaire is designed to collect categorical data, non-parametric approach is the common statistical procedure. However, similar results were also obtained as parametric approach, regardless the fact of non-normal distributed data. Thus, it suggests that parametric approach can be applicable for consumer study with large number of respondents, even though it may not satisfy the assumption of ANOVA (Analysis of Variances).

  20. Assessing T cell clonal size distribution: a non-parametric approach.

    Science.gov (United States)

    Bolkhovskaya, Olesya V; Zorin, Daniil Yu; Ivanchenko, Mikhail V

    2014-01-01

    Clonal structure of the human peripheral T-cell repertoire is shaped by a number of homeostatic mechanisms, including antigen presentation, cytokine and cell regulation. Its accurate tuning leads to a remarkable ability to combat pathogens in all their variety, while systemic failures may lead to severe consequences like autoimmune diseases. Here we develop and make use of a non-parametric statistical approach to assess T cell clonal size distributions from recent next generation sequencing data. For 41 healthy individuals and a patient with ankylosing spondylitis, who undergone treatment, we invariably find power law scaling over several decades and for the first time calculate quantitatively meaningful values of decay exponent. It has proved to be much the same among healthy donors, significantly different for an autoimmune patient before the therapy, and converging towards a typical value afterwards. We discuss implications of the findings for theoretical understanding and mathematical modeling of adaptive immunity.

  1. Assessing T cell clonal size distribution: a non-parametric approach.

    Directory of Open Access Journals (Sweden)

    Olesya V Bolkhovskaya

    Full Text Available Clonal structure of the human peripheral T-cell repertoire is shaped by a number of homeostatic mechanisms, including antigen presentation, cytokine and cell regulation. Its accurate tuning leads to a remarkable ability to combat pathogens in all their variety, while systemic failures may lead to severe consequences like autoimmune diseases. Here we develop and make use of a non-parametric statistical approach to assess T cell clonal size distributions from recent next generation sequencing data. For 41 healthy individuals and a patient with ankylosing spondylitis, who undergone treatment, we invariably find power law scaling over several decades and for the first time calculate quantitatively meaningful values of decay exponent. It has proved to be much the same among healthy donors, significantly different for an autoimmune patient before the therapy, and converging towards a typical value afterwards. We discuss implications of the findings for theoretical understanding and mathematical modeling of adaptive immunity.

  2. Non-parametric and least squares Langley plot methods

    Science.gov (United States)

    Kiedron, P. W.; Michalsky, J. J.

    2016-01-01

    Langley plots are used to calibrate sun radiometers primarily for the measurement of the aerosol component of the atmosphere that attenuates (scatters and absorbs) incoming direct solar radiation. In principle, the calibration of a sun radiometer is a straightforward application of the Bouguer-Lambert-Beer law V = V0e-τ ṡ m, where a plot of ln(V) voltage vs. m air mass yields a straight line with intercept ln(V0). This ln(V0) subsequently can be used to solve for τ for any measurement of V and calculation of m. This calibration works well on some high mountain sites, but the application of the Langley plot calibration technique is more complicated at other, more interesting, locales. This paper is concerned with ferreting out calibrations at difficult sites and examining and comparing a number of conventional and non-conventional methods for obtaining successful Langley plots. The 11 techniques discussed indicate that both least squares and various non-parametric techniques produce satisfactory calibrations with no significant differences among them when the time series of ln(V0)'s are smoothed and interpolated with median and mean moving window filters.

  3. A local non-parametric model for trade sign inference

    Science.gov (United States)

    Blazejewski, Adam; Coggins, Richard

    2005-03-01

    We investigate a regularity in market order submission strategies for 12 stocks with large market capitalization on the Australian Stock Exchange. The regularity is evidenced by a predictable relationship between the trade sign (trade initiator), size of the trade, and the contents of the limit order book before the trade. We demonstrate this predictability by developing an empirical inference model to classify trades into buyer-initiated and seller-initiated. The model employs a local non-parametric method, k-nearest neighbor, which in the past was used successfully for chaotic time series prediction. The k-nearest neighbor with three predictor variables achieves an average out-of-sample classification accuracy of 71.40%, compared to 63.32% for the linear logistic regression with seven predictor variables. The result suggests that a non-linear approach may produce a more parsimonious trade sign inference model with a higher out-of-sample classification accuracy. Furthermore, for most of our stocks the observed regularity in market order submissions seems to have a memory of at least 30 trading days.

  4. Non-parametric algorithm to isolate chunks in response sequences

    Directory of Open Access Journals (Sweden)

    Andrea Alamia

    2016-09-01

    Full Text Available Chunking consists in grouping items of a sequence into small clusters, named chunks, with the assumed goal of lessening working memory load. Despite extensive research, the current methods used to detect chunks, and to identify different chunking strategies, remain discordant and difficult to implement. Here, we propose a simple and reliable method to identify chunks in a sequence and to determine their stability across blocks.This algorithm is based on a ranking method and its major novelty is that it provides concomitantly both the features of individual chunk in a given sequence, and an overall index that quantifies the chunking pattern consistency across sequences. The analysis of simulated data confirmed the validity of our method in different conditions of noise, chunk lengths and chunk numbers; moreover, we found that this algorithm was particularly efficient in the noise range observed in real data, provided that at least 4 sequence repetitions were included in each experimental block. Furthermore, we applied this algorithm to actual reaction time series gathered from 3 published experiments and were able to confirm the findings obtained in the original reports. In conclusion, this novel algorithm is easy to implement, is robust to outliers and provides concurrent and reliable estimation of chunk position and chunking dynamics, making it useful to study both sequence-specific and general chunking effects.The algorithm is available at: https://github.com/artipago/Non-parametric-algorithm-to-isolate-chunks-in-response-sequences

  5. Non-parametric Bayesian networks: Improving theory and reviewing applications

    International Nuclear Information System (INIS)

    Hanea, Anca; Morales Napoles, Oswaldo; Ababei, Dan

    2015-01-01

    Applications in various domains often lead to high dimensional dependence modelling. A Bayesian network (BN) is a probabilistic graphical model that provides an elegant way of expressing the joint distribution of a large number of interrelated variables. BNs have been successfully used to represent uncertain knowledge in a variety of fields. The majority of applications use discrete BNs, i.e. BNs whose nodes represent discrete variables. Integrating continuous variables in BNs is an area fraught with difficulty. Several methods that handle discrete-continuous BNs have been proposed in the literature. This paper concentrates only on one method called non-parametric BNs (NPBNs). NPBNs were introduced in 2004 and they have been or are currently being used in at least twelve professional applications. This paper provides a short introduction to NPBNs, a couple of theoretical advances, and an overview of applications. The aim of the paper is twofold: one is to present the latest improvements of the theory underlying NPBNs, and the other is to complement the existing overviews of BNs applications with the NPNBs applications. The latter opens the opportunity to discuss some difficulties that applications pose to the theoretical framework and in this way offers some NPBN modelling guidance to practitioners. - Highlights: • The paper gives an overview of the current NPBNs methodology. • We extend the NPBN methodology by relaxing the conditions of one of its fundamental theorems. • We propose improvements of the data mining algorithm for the NPBNs. • We review the professional applications of the NPBNs.

  6. Reliable estimates of predictive uncertainty for an Alpine catchment using a non-parametric methodology

    Science.gov (United States)

    Matos, José P.; Schaefli, Bettina; Schleiss, Anton J.

    2017-04-01

    Uncertainty affects hydrological modelling efforts from the very measurements (or forecasts) that serve as inputs to the more or less inaccurate predictions that are produced. Uncertainty is truly inescapable in hydrology and yet, due to the theoretical and technical hurdles associated with its quantification, it is at times still neglected or estimated only qualitatively. In recent years the scientific community has made a significant effort towards quantifying this hydrologic prediction uncertainty. Despite this, most of the developed methodologies can be computationally demanding, are complex from a theoretical point of view, require substantial expertise to be employed, and are constrained by a number of assumptions about the model error distribution. These assumptions limit the reliability of many methods in case of errors that show particular cases of non-normality, heteroscedasticity, or autocorrelation. The present contribution builds on a non-parametric data-driven approach that was developed for uncertainty quantification in operational (real-time) forecasting settings. The approach is based on the concept of Pareto optimality and can be used as a standalone forecasting tool or as a postprocessor. By virtue of its non-parametric nature and a general operating principle, it can be applied directly and with ease to predictions of streamflow, water stage, or even accumulated runoff. Also, it is a methodology capable of coping with high heteroscedasticity and seasonal hydrological regimes (e.g. snowmelt and rainfall driven events in the same catchment). Finally, the training and operation of the model are very fast, making it a tool particularly adapted to operational use. To illustrate its practical use, the uncertainty quantification method is coupled with a process-based hydrological model to produce statistically reliable forecasts for an Alpine catchment located in Switzerland. Results are presented and discussed in terms of their reliability and

  7. Non-parametric estimation of low-concentration benzene metabolism.

    Science.gov (United States)

    Cox, Louis A; Schnatter, A Robert; Boogaard, Peter J; Banton, Marcy; Ketelslegers, Hans B

    2017-12-25

    Two apparently contradictory findings in the literature on low-dose human metabolism of benzene are as follows. First, metabolism is approximately linear at low concentrations, e.g., below 10 ppm. This is consistent with decades of quantitative modeling of benzene pharmacokinetics and dose-dependent metabolism. Second, measured benzene exposure and metabolite concentrations for occupationally exposed benzene workers in Tianjin, China show that dose-specific metabolism (DSM) ratios of metabolite concentrations per ppm of benzene in air decrease steadily with benzene concentration, with the steepest decreases below 3 ppm. This has been interpreted as indicating that metabolism at low concentrations of benzene is highly nonlinear. We reexamine the data using non-parametric methods. Our main conclusion is that both findings are correct; they are not contradictory. Low-concentration metabolism can be linear, with metabolite concentrations proportional to benzene concentrations in air, and yet DSM ratios can still decrease with benzene concentrations. This is because a ratio of random variables can be negatively correlated with its own denominator even if the mean of the numerator is proportional to the denominator. Interpreting DSM ratios that decrease with air benzene concentrations as evidence of nonlinear metabolism is therefore unwarranted when plots of metabolite concentrations against benzene ppm in air show approximately straight-line relationships between them, as in the Tianjin data. Thus, an apparent contradiction that has fueled heated discussions in the recent literature can be resolved by recognizing that highly nonlinear, decreasing DSM ratios are consistent with linear metabolism. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

  8. Modelación de episodios críticos de contaminación por material particulado (PM10 en Santiago de Chile: Comparación de la eficiencia predictiva de los modelos paramétricos y no paramétricos Modeling critical episodes of air pollution by PM10 in Santiago, Chile: Comparison of the predictive efficiency of parametric and non-parametric statistical models

    Directory of Open Access Journals (Sweden)

    Sergio A. Alvarado

    2010-12-01

    Full Text Available Objetivo: Evaluar la eficiencia predictiva de modelos estadísticos paramétricos y no paramétricos para predecir episodios críticos de contaminación por material particulado PM10 del día siguiente, que superen en Santiago de Chile la norma de calidad diaria. Una predicción adecuada de tales episodios permite a la autoridad decretar medidas restrictivas que aminoren la gravedad del episodio, y consecuentemente proteger la salud de la comunidad. Método: Se trabajó con las concentraciones de material particulado PM10 registradas en una estación asociada a la red de monitorización de la calidad del aire MACAM-2, considerando 152 observaciones diarias de 14 variables, y con información meteorológica registrada durante los años 2001 a 2004. Se ajustaron modelos estadísticos paramétricos Gamma usando el paquete estadístico STATA v11, y no paramétricos usando una demo del software estadístico MARS v 2.0 distribuida por Salford-Systems. Resultados: Ambos métodos de modelación presentan una alta correlación entre los valores observados y los predichos. Los modelos Gamma presentan mejores aciertos que MARS para las concentraciones de PM10 con valores Objective: To evaluate the predictive efficiency of two statistical models (one parametric and the other non-parametric to predict critical episodes of air pollution exceeding daily air quality standards in Santiago, Chile by using the next day PM10 maximum 24h value. Accurate prediction of such episodes would allow restrictive measures to be applied by health authorities to reduce their seriousness and protect the community´s health. Methods: We used the PM10 concentrations registered by a station of the Air Quality Monitoring Network (152 daily observations of 14 variables and meteorological information gathered from 2001 to 2004. To construct predictive models, we fitted a parametric Gamma model using STATA v11 software and a non-parametric MARS model by using a demo version of Salford

  9. Kernel bandwidth estimation for non-parametric density estimation: a comparative study

    CSIR Research Space (South Africa)

    Van der Walt, CM

    2013-12-01

    Full Text Available We investigate the performance of conventional bandwidth estimators for non-parametric kernel density estimation on a number of representative pattern-recognition tasks, to gain a better understanding of the behaviour of these estimators in high...

  10. Zero- vs. one-dimensional, parametric vs. non-parametric, and confidence interval vs. hypothesis testing procedures in one-dimensional biomechanical trajectory analysis.

    Science.gov (United States)

    Pataky, Todd C; Vanrenterghem, Jos; Robinson, Mark A

    2015-05-01

    Biomechanical processes are often manifested as one-dimensional (1D) trajectories. It has been shown that 1D confidence intervals (CIs) are biased when based on 0D statistical procedures, and the non-parametric 1D bootstrap CI has emerged in the Biomechanics literature as a viable solution. The primary purpose of this paper was to clarify that, for 1D biomechanics datasets, the distinction between 0D and 1D methods is much more important than the distinction between parametric and non-parametric procedures. A secondary purpose was to demonstrate that a parametric equivalent to the 1D bootstrap exists in the form of a random field theory (RFT) correction for multiple comparisons. To emphasize these points we analyzed six datasets consisting of force and kinematic trajectories in one-sample, paired, two-sample and regression designs. Results showed, first, that the 1D bootstrap and other 1D non-parametric CIs were qualitatively identical to RFT CIs, and all were very different from 0D CIs. Second, 1D parametric and 1D non-parametric hypothesis testing results were qualitatively identical for all six datasets. Last, we highlight the limitations of 1D CIs by demonstrating that they are complex, design-dependent, and thus non-generalizable. These results suggest that (i) analyses of 1D data based on 0D models of randomness are generally biased unless one explicitly identifies 0D variables before the experiment, and (ii) parametric and non-parametric 1D hypothesis testing provide an unambiguous framework for analysis when one׳s hypothesis explicitly or implicitly pertains to whole 1D trajectories. Copyright © 2015 Elsevier Ltd. All rights reserved.

  11. Impulse response identification with deterministic inputs using non-parametric methods

    International Nuclear Information System (INIS)

    Bhargava, U.K.; Kashyap, R.L.; Goodman, D.M.

    1985-01-01

    This paper addresses the problem of impulse response identification using non-parametric methods. Although the techniques developed herein apply to the truncated, untruncated, and the circulant models, we focus on the truncated model which is useful in certain applications. Two methods of impulse response identification will be presented. The first is based on the minimization of the C/sub L/ Statistic, which is an estimate of the mean-square prediction error; the second is a Bayesian approach. For both of these methods, we consider the effects of using both the identity matrix and the Laplacian matrix as weights on the energy in the impulse response. In addition, we present a method for estimating the effective length of the impulse response. Estimating the length is particularly important in the truncated case. Finally, we develop a method for estimating the noise variance at the output. Often, prior information on the noise variance is not available, and a good estimate is crucial to the success of estimating the impulse response with a nonparametric technique

  12. The taxonomy statistic uncovers novel clinical patterns in a population of ischemic stroke patients.

    Directory of Open Access Journals (Sweden)

    Andrzej Tukiendorf

    Full Text Available In this paper, we describe a simple taxonomic approach for clinical data mining elaborated by Marczewski and Steinhaus (M-S, whose performance equals the advanced statistical methodology known as the expectation-maximization (E-M algorithm. We tested these two methods on a cohort of ischemic stroke patients. The comparison of both methods revealed strong agreement. Direct agreement between M-S and E-M classifications reached 83%, while Cohen's coefficient of agreement was κ = 0.766(P < 0.0001. The statistical analysis conducted and the outcomes obtained in this paper revealed novel clinical patterns in ischemic stroke patients. The aim of the study was to evaluate the clinical usefulness of Marczewski-Steinhaus' taxonomic approach as a tool for the detection of novel patterns of data in ischemic stroke patients and the prediction of disease outcome. In terms of the identification of fairly frequent types of stroke patients using their age, National Institutes of Health Stroke Scale (NIHSS, and diabetes mellitus (DM status, when dealing with rough characteristics of patients, four particular types of patients are recognized, which cannot be identified by means of routine clinical methods. Following the obtained taxonomical outcomes, the strong correlation between the health status at moment of admission to emergency department (ED and the subsequent recovery of patients is established. Moreover, popularization and simplification of the ideas of advanced mathematicians may provide an unconventional explorative platform for clinical problems.

  13. Evaluation of model-based versus non-parametric monaural noise-reduction approaches for hearing aids.

    Science.gov (United States)

    Harlander, Niklas; Rosenkranz, Tobias; Hohmann, Volker

    2012-08-01

    Single channel noise reduction has been well investigated and seems to have reached its limits in terms of speech intelligibility improvement, however, the quality of such schemes can still be advanced. This study tests to what extent novel model-based processing schemes might improve performance in particular for non-stationary noise conditions. Two prototype model-based algorithms, a speech-model-based, and a auditory-model-based algorithm were compared to a state-of-the-art non-parametric minimum statistics algorithm. A speech intelligibility test, preference rating, and listening effort scaling were performed. Additionally, three objective quality measures for the signal, background, and overall distortions were applied. For a better comparison of all algorithms, particular attention was given to the usage of the similar Wiener-based gain rule. The perceptual investigation was performed with fourteen hearing-impaired subjects. The results revealed that the non-parametric algorithm and the auditory model-based algorithm did not affect speech intelligibility, whereas the speech-model-based algorithm slightly decreased intelligibility. In terms of subjective quality, both model-based algorithms perform better than the unprocessed condition and the reference in particular for highly non-stationary noise environments. Data support the hypothesis that model-based algorithms are promising for improving performance in non-stationary noise conditions.

  14. A non-parametric hidden Markov model for climate state identification

    Directory of Open Access Journals (Sweden)

    M. F. Lambert

    2003-01-01

    Full Text Available Hidden Markov models (HMMs can allow for the varying wet and dry cycles in the climate without the need to simulate supplementary climate variables. The fitting of a parametric HMM relies upon assumptions for the state conditional distributions. It is shown that inappropriate assumptions about state conditional distributions can lead to biased estimates of state transition probabilities. An alternative non-parametric model with a hidden state structure that overcomes this problem is described. It is shown that a two-state non-parametric model produces accurate estimates of both transition probabilities and the state conditional distributions. The non-parametric model can be used directly or as a technique for identifying appropriate state conditional distributions to apply when fitting a parametric HMM. The non-parametric model is fitted to data from ten rainfall stations and four streamflow gauging stations at varying distances inland from the Pacific coast of Australia. Evidence for hydrological persistence, though not mathematical persistence, was identified in both rainfall and streamflow records, with the latter showing hidden states with longer sojourn times. Persistence appears to increase with distance from the coast. Keywords: Hidden Markov models, non-parametric, two-state model, climate states, persistence, probability distributions

  15. Non-parametric analysis of seasonality in birth and multiple sclerosis risk in second generation of migrants in Kuwait.

    Science.gov (United States)

    Akhtar, Saeed; Alroughani, Raed; Al-Shammari, Ahmad; Al-Abkal, Jarrah; Ayad, Yasser

    2014-08-26

    There are inconsistent reports about multiple sclerosis (MS) risk among migrants from low to high MS risk geographical regions. This study assessed the overall MS incidence and evaluated seasonality in birth and subsequent MS risk later in the life in second generation of migrants born and lived in Kuwait. We assessed the overall and gender-specific MS risk in second generation of migrants born and lived in Kuwait between January 1, 1950 and April 30, 2013. Data on migrants' MS patients diagnosed and registered in Kuwait National MS Registry were used. Hewitt's non-parametric test was carried out to evaluate the seasonality in migrants' MS births in comparison with the second generation migrants' births in general population. During the study period, an overall risk of migrants' MS births (per 100,000 non-Kuwaiti births in general population) was 23.8 (95% CI: 20.8 - 27.0). Gender-specific MS risk showed that non-Kuwaiti female had statistically significant (p = 0.003) higher risk (28.6; 95% CI: 24.2 - 33.7) than non-Kuwaiti males (18.7; 95% CI: 15.1-23.0). The month-specific distribution of migrants' MS births compared with migrants' births in general population did not differ significantly (χ2 goodness-of-fit test statistic = 9.51, p = 0.575). Hewitt's non-parametric test revealed an evidence of slight but statistically non-significant (p = 0.090) increased tendency of migrants' MS births during September through February. The proportion of migrants' MS births (per 100,000 migrants' births in general population) over the study period was 23.8 (95% CI: 20.8 - 27.0), which was statistically significantly higher than the previously reported Kuwaiti national MS births (16.2; 95% CI: 15.1-17.4) in Kuwait. Non-parametric analysis showed slight but statistically non-significant increased tendency of migrants' MS births from September through February. Knowledge of MS risk factors and how and when they act among genetically vulnerable individuals from

  16. A non-parametric peak calling algorithm for DamID-Seq.

    Directory of Open Access Journals (Sweden)

    Renhua Li

    Full Text Available Protein-DNA interactions play a significant role in gene regulation and expression. In order to identify transcription factor binding sites (TFBS of double sex (DSX-an important transcription factor in sex determination, we applied the DNA adenine methylation identification (DamID technology to the fat body tissue of Drosophila, followed by deep sequencing (DamID-Seq. One feature of DamID-Seq data is that induced adenine methylation signals are not assured to be symmetrically distributed at TFBS, which renders the existing peak calling algorithms for ChIP-Seq, including SPP and MACS, inappropriate for DamID-Seq data. This challenged us to develop a new algorithm for peak calling. A challenge in peaking calling based on sequence data is estimating the averaged behavior of background signals. We applied a bootstrap resampling method to short sequence reads in the control (Dam only. After data quality check and mapping reads to a reference genome, the peaking calling procedure compromises the following steps: 1 reads resampling; 2 reads scaling (normalization and computing signal-to-noise fold changes; 3 filtering; 4 Calling peaks based on a statistically significant threshold. This is a non-parametric method for peak calling (NPPC. We also used irreproducible discovery rate (IDR analysis, as well as ChIP-Seq data to compare the peaks called by the NPPC. We identified approximately 6,000 peaks for DSX, which point to 1,225 genes related to the fat body tissue difference between female and male Drosophila. Statistical evidence from IDR analysis indicated that these peaks are reproducible across biological replicates. In addition, these peaks are comparable to those identified by use of ChIP-Seq on S2 cells, in terms of peak number, location, and peaks width.

  17. A non-parametric peak calling algorithm for DamID-Seq.

    Science.gov (United States)

    Li, Renhua; Hempel, Leonie U; Jiang, Tingbo

    2015-01-01

    Protein-DNA interactions play a significant role in gene regulation and expression. In order to identify transcription factor binding sites (TFBS) of double sex (DSX)-an important transcription factor in sex determination, we applied the DNA adenine methylation identification (DamID) technology to the fat body tissue of Drosophila, followed by deep sequencing (DamID-Seq). One feature of DamID-Seq data is that induced adenine methylation signals are not assured to be symmetrically distributed at TFBS, which renders the existing peak calling algorithms for ChIP-Seq, including SPP and MACS, inappropriate for DamID-Seq data. This challenged us to develop a new algorithm for peak calling. A challenge in peaking calling based on sequence data is estimating the averaged behavior of background signals. We applied a bootstrap resampling method to short sequence reads in the control (Dam only). After data quality check and mapping reads to a reference genome, the peaking calling procedure compromises the following steps: 1) reads resampling; 2) reads scaling (normalization) and computing signal-to-noise fold changes; 3) filtering; 4) Calling peaks based on a statistically significant threshold. This is a non-parametric method for peak calling (NPPC). We also used irreproducible discovery rate (IDR) analysis, as well as ChIP-Seq data to compare the peaks called by the NPPC. We identified approximately 6,000 peaks for DSX, which point to 1,225 genes related to the fat body tissue difference between female and male Drosophila. Statistical evidence from IDR analysis indicated that these peaks are reproducible across biological replicates. In addition, these peaks are comparable to those identified by use of ChIP-Seq on S2 cells, in terms of peak number, location, and peaks width.

  18. A Non-Parametric Surrogate-based Test of Significance for T-Wave Alternans Detection

    Science.gov (United States)

    Nemati, Shamim; Abdala, Omar; Bazán, Violeta; Yim-Yeh, Susie; Malhotra, Atul; Clifford, Gari

    2010-01-01

    We present a non-parametric adaptive surrogate test that allows for the differentiation of statistically significant T-Wave Alternans (TWA) from alternating patterns that can be solely explained by the statistics of noise. The proposed test is based on estimating the distribution of noise induced alternating patterns in a beat sequence from a set of surrogate data derived from repeated reshuffling of the original beat sequence. Thus, in assessing the significance of the observed alternating patterns in the data no assumptions are made about the underlying noise distribution. In addition, since the distribution of noise-induced alternans magnitudes is calculated separately for each sequence of beats within the analysis window, the method is robust to data non-stationarities in both noise and TWA. The proposed surrogate method for rejecting noise was compared to the standard noise rejection methods used with the Spectral Method (SM) and the Modified Moving Average (MMA) techniques. Using a previously described realistic multi-lead model of TWA, and real physiological noise, we demonstrate the proposed approach reduces false TWA detections, while maintaining a lower missed TWA detection compared with all the other methods tested. A simple averaging-based TWA estimation algorithm was coupled with the surrogate significance testing and was evaluated on three public databases; the Normal Sinus Rhythm Database (NRSDB), the Chronic Heart Failure Database (CHFDB) and the Sudden Cardiac Death Database (SCDDB). Differences in TWA amplitudes between each database were evaluated at matched heart rate (HR) intervals from 40 to 120 beats per minute (BPM). Using the two-sample Kolmogorov-Smirnov test, we found that significant differences in TWA levels exist between each patient group at all decades of heart rates. The most marked difference was generally found at higher heart rates, and the new technique resulted in a larger margin of separability between patient populations than

  19. Non-Parametric Bayesian Updating within the Assessment of Reliability for Offshore Wind Turbine Support Structures

    DEFF Research Database (Denmark)

    Ramirez, José Rangel; Sørensen, John Dalsgaard

    2011-01-01

    This work illustrates the updating and incorporation of information in the assessment of fatigue reliability for offshore wind turbine. The new information, coming from external and condition monitoring can be used to direct updating of the stochastic variables through a non-parametric Bayesian...... updating approach and be integrated in the reliability analysis by a third-order polynomial chaos expansion approximation. Although Classical Bayesian updating approaches are often used because of its parametric formulation, non-parametric approaches are better alternatives for multi-parametric updating...... with a non-conjugating formulation. The results in this paper show the influence on the time dependent updated reliability when non-parametric and classical Bayesian approaches are used. Further, the influence on the reliability of the number of updated parameters is illustrated....

  20. [Delirium in stroke patients : Critical analysis of statistical procedures for the identification of risk factors].

    Science.gov (United States)

    Nydahl, P; Margraf, N G; Ewers, A

    2017-04-01

    Delirium is a relevant complication following an acute stroke. It is a multifactor occurrence with numerous interacting risk factors that alternately influence each other. The risk factors of delirium in stroke patients are often based on limited clinical studies. The statistical procedures and clinical relevance of delirium related risk factors in adult stroke patients should therefore be questioned. This secondary analysis includes clinically relevant studies that give evidence for the clinical relevance and statistical significance of delirium-associated risk factors in stroke patients. The quality of the reporting of regression analyses was assessed using Ottenbacher's quality criteria. The delirium-associated risk factors identified were examined with regard to statistical significance using the Bonferroni method of multiple testing for forming incorrect positive hypotheses. This was followed by a literature-based discussion on clinical relevance. Nine clinical studies were included. None of the studies fulfilled all the prerequisites and assumptions given for the reporting of regression analyses according to Ottenbacher. Of the 108 delirium-associated risk factors, a total of 48 (44.4%) were significant, whereby a total of 28 (58.3%) were false positive after Bonferroni correction. Following a literature-based discussion on clinical relevance, the assumption of statistical significance and clinical relevance could be found for only four risk factors (dementia or cognitive impairment, total anterior infarct, severe infarct and infections). The statistical procedures used in the existing literature are questionable, as are their results. A post-hoc analysis and critical appraisal reduced the number of possible delirium-associated risk factors to just a few clinically relevant factors.

  1. Power of non-parametric linkage analysis in mapping genes contributing to human longevity in long-lived sib-pairs

    DEFF Research Database (Denmark)

    Tan, Qihua; Zhao, J H; Iachine, I

    2004-01-01

    This report investigates the power issue in applying the non-parametric linkage analysis of affected sib-pairs (ASP) [Kruglyak and Lander, 1995: Am J Hum Genet 57:439-454] to localize genes that contribute to human longevity using long-lived sib-pairs. Data were simulated by introducing a recently...... developed statistical model for measuring marker-longevity associations [Yashin et al., 1999: Am J Hum Genet 65:1178-1193], enabling direct power comparison between linkage and association approaches. The non-parametric linkage (NPL) scores estimated in the region harboring the causal allele are evaluated...... in case of a dominant effect. Although the power issue may depend heavily on the true genetic nature in maintaining survival, our study suggests that results from small-scale sib-pair investigations should be referred with caution, given the complexity of human longevity....

  2. The Support Reduction Algorithm for Computing Non-Parametric Function Estimates in Mixture Models

    OpenAIRE

    GROENEBOOM, PIET; JONGBLOED, GEURT; WELLNER, JON A.

    2008-01-01

    In this paper, we study an algorithm (which we call the support reduction algorithm) that can be used to compute non-parametric M-estimators in mixture models. The algorithm is compared with natural competitors in the context of convex regression and the ‘Aspect problem’ in quantum physics.

  3. Non-parametric production analysis of pesticides use in the Netherlands

    NARCIS (Netherlands)

    Oude Lansink, A.G.J.M.; Silva, E.

    2004-01-01

    Many previous empirical studies on the productivity of pesticides suggest that pesticides are under-utilized in agriculture despite the general held believe that these inputs are substantially over-utilized. This paper uses data envelopment analysis (DEA) to calculate non-parametric measures of the

  4. Measuring the influence of networks on transaction costs using a non-parametric regression technique

    DEFF Research Database (Denmark)

    Henningsen, Géraldine; Henningsen, Arne; Henning, Christian H.C.A.

    . We empirically analyse the effect of networks on productivity using a cross-validated local linear non-parametric regression technique and a data set of 384 farms in Poland. Our empirical study generally supports our hypothesis that networks affect productivity. Large and dense trading networks...

  5. Assessing pupil and school performance by non-parametric and parametric techniques

    NARCIS (Netherlands)

    de Witte, K.; Thanassoulis, E.; Simpson, G.; Battisti, G.; Charlesworth-May, A.

    2010-01-01

    This paper discusses the use of the non-parametric free disposal hull (FDH) and the parametric multi-level model (MLM) as alternative methods for measuring pupil and school attainment where hierarchical structured data are available. Using robust FDH estimates, we show how to decompose the overall

  6. A non-parametric Bayesian approach to decompounding from high frequency data

    NARCIS (Netherlands)

    Gugushvili, Shota; van der Meulen, F.H.; Spreij, Peter

    2016-01-01

    Given a sample from a discretely observed compound Poisson process, we consider non-parametric estimation of the density f0 of its jump sizes, as well as of its intensity λ0. We take a Bayesian approach to the problem and specify the prior on f0 as the Dirichlet location mixture of normal densities.

  7. Non-parametric Estimation of Diffusion-Paths Using Wavelet Scaling Methods

    DEFF Research Database (Denmark)

    Høg, Esben

    In continuous time, diffusion processes have been used for modelling financial dynamics for a long time. For example the Ornstein-Uhlenbeck process (the simplest mean-reverting process) has been used to model non-speculative price processes. We discuss non--parametric estimation of these processes...

  8. Non-Parametric Estimation of Diffusion-Paths Using Wavelet Scaling Methods

    DEFF Research Database (Denmark)

    Høg, Esben

    2003-01-01

    In continuous time, diffusion processes have been used for modelling financial dynamics for a long time. For example the Ornstein-Uhlenbeck process (the simplest mean--reverting process) has been used to model non-speculative price processes. We discuss non--parametric estimation of these processes...

  9. Combining parametric, semi-parametric, and non-parametric survival models with stacked survival models.

    Science.gov (United States)

    Wey, Andrew; Connett, John; Rudser, Kyle

    2015-07-01

    For estimating conditional survival functions, non-parametric estimators can be preferred to parametric and semi-parametric estimators due to relaxed assumptions that enable robust estimation. Yet, even when misspecified, parametric and semi-parametric estimators can possess better operating characteristics in small sample sizes due to smaller variance than non-parametric estimators. Fundamentally, this is a bias-variance trade-off situation in that the sample size is not large enough to take advantage of the low bias of non-parametric estimation. Stacked survival models estimate an optimally weighted combination of models that can span parametric, semi-parametric, and non-parametric models by minimizing prediction error. An extensive simulation study demonstrates that stacked survival models consistently perform well across a wide range of scenarios by adaptively balancing the strengths and weaknesses of individual candidate survival models. In addition, stacked survival models perform as well as or better than the model selected through cross-validation. Finally, stacked survival models are applied to a well-known German breast cancer study. © The Author 2015. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  10. Non-Parametric Bayesian Updating within the Assessment of Reliability for Offshore Wind Turbine Support Structures

    DEFF Research Database (Denmark)

    Ramirez, José Rangel; Sørensen, John Dalsgaard

    2011-01-01

    This work illustrates the updating and incorporation of information in the assessment of fatigue reliability for offshore wind turbine. The new information, coming from external and condition monitoring can be used to direct updating of the stochastic variables through a non-parametric Bayesian u...

  11. A comparative study of non-parametric models for identification of ...

    African Journals Online (AJOL)

    However, the frequency response method using random binary signals was good for unpredicted white noise characteristics and considered the best method for non-parametric system identifica-tion. The autoregressive external input (ARX) model was very useful for system identification, but on applicati-on, few input ...

  12. A non-parametric hierarchical model to discover behavior dynamics from tracks

    NARCIS (Netherlands)

    Kooij, J.F.P.; Englebienne, G.; Gavrila, D.M.

    2012-01-01

    We present a novel non-parametric Bayesian model to jointly discover the dynamics of low-level actions and high-level behaviors of tracked people in open environments. Our model represents behaviors as Markov chains of actions which capture high-level temporal dynamics. Actions may be shared by

  13. Experimental Sentinel-2 LAI estimation using parametric, non-parametric and physical retrieval methods - A comparison

    NARCIS (Netherlands)

    Verrelst, Jochem; Rivera, Juan Pablo; Veroustraete, Frank; Muñoz-Marí, Jordi; Clevers, J.G.P.W.; Camps-Valls, Gustau; Moreno, José

    2015-01-01

    Given the forthcoming availability of Sentinel-2 (S2) images, this paper provides a systematic comparison of retrieval accuracy and processing speed of a multitude of parametric, non-parametric and physically-based retrieval methods using simulated S2 data. An experimental field dataset (SPARC),

  14. Low default credit scoring using two-class non-parametric kernel density estimation

    CSIR Research Space (South Africa)

    Rademeyer, E

    2016-12-01

    Full Text Available This paper investigates the performance of two-class classification credit scoring data sets with low default ratios. The standard two-class parametric Gaussian and non-parametric Parzen classifiers are extended, using Bayes’ rule, to include either...

  15. Overview of NonParametric Combination-based permutation tests for Multivariate multi-sample problems

    Directory of Open Access Journals (Sweden)

    Rosa Arboretti Giancristofaro

    2014-09-01

    Full Text Available In this work we present a review on nonparametric combination-based permutation tests along with SAS macros allowing to deal with two-sample and one-way MANOVA design problems, within NonParametric Combination methodology framework. Applications to real case studies are also presented.

  16. Parametric and Non-Parametric Vibration-Based Structural Identification Under Earthquake Excitation

    Science.gov (United States)

    Pentaris, Fragkiskos P.; Fouskitakis, George N.

    2014-05-01

    The problem of modal identification in civil structures is of crucial importance, and thus has been receiving increasing attention in recent years. Vibration-based methods are quite promising as they are capable of identifying the structure's global characteristics, they are relatively easy to implement and they tend to be time effective and less expensive than most alternatives [1]. This paper focuses on the off-line structural/modal identification of civil (concrete) structures subjected to low-level earthquake excitations, under which, they remain within their linear operating regime. Earthquakes and their details are recorded and provided by the seismological network of Crete [2], which 'monitors' the broad region of south Hellenic arc, an active seismic region which functions as a natural laboratory for earthquake engineering of this kind. A sufficient number of seismic events are analyzed in order to reveal the modal characteristics of the structures under study, that consist of the two concrete buildings of the School of Applied Sciences, Technological Education Institute of Crete, located in Chania, Crete, Hellas. Both buildings are equipped with high-sensitivity and accuracy seismographs - providing acceleration measurements - established at the basement (structure's foundation) presently considered as the ground's acceleration (excitation) and at all levels (ground floor, 1st floor, 2nd floor and terrace). Further details regarding the instrumentation setup and data acquisition may be found in [3]. The present study invokes stochastic, both non-parametric (frequency-based) and parametric methods for structural/modal identification (natural frequencies and/or damping ratios). Non-parametric methods include Welch-based spectrum and Frequency response Function (FrF) estimation, while parametric methods, include AutoRegressive (AR), AutoRegressive with eXogeneous input (ARX) and Autoregressive Moving-Average with eXogeneous input (ARMAX) models[4, 5

  17. Mathematical statistics

    CERN Document Server

    Pestman, Wiebe R

    2009-01-01

    This textbook provides a broad and solid introduction to mathematical statistics, including the classical subjects hypothesis testing, normal regression analysis, and normal analysis of variance. In addition, non-parametric statistics and vectorial statistics are considered, as well as applications of stochastic analysis in modern statistics, e.g., Kolmogorov-Smirnov testing, smoothing techniques, robustness and density estimation. For students with some elementary mathematical background. With many exercises. Prerequisites from measure theory and linear algebra are presented.

  18. A multitemporal and non-parametric approach for assessing the impacts of drought on vegetation greenness

    DEFF Research Database (Denmark)

    Carrao, Hugo; Sepulcre, Guadalupe; Horion, Stéphanie Marie Anne F

    2013-01-01

    This study evaluates the relationship between the frequency and duration of meteorological droughts and the subsequent temporal changes on the quantity of actively photosynthesizing biomass (greenness) estimated from satellite imagery on rainfed croplands in Latin America. An innovative non-parametric...... and non-supervised approach, based on the Fisher-Jenks optimal classification algorithm, is used to identify multi-scale meteorological droughts on the basis of empirical cumulative distributions of 1, 3, 6, and 12-monthly precipitation totals. As input data for the classifier, we use the gridded GPCC...... for the period between 1998 and 2010. The time-series analysis of vegetation greenness is performed during the growing season with a non-parametric method, namely the seasonal Relative Greenness (RG) of spatially accumulated fAPAR. The Global Land Cover map of 2000 and the GlobCover maps of 2005/2006 and 2009...

  19. Hadron Energy Reconstruction for ATLAS Barrel Combined Calorimeter Using Non-Parametrical Method

    CERN Document Server

    Kulchitskii, Yu A

    2000-01-01

    Hadron energy reconstruction for the ATLAS barrel prototype combined calorimeter in the framework of the non-parametrical method is discussed. The non-parametrical method utilizes only the known e/h ratios and the electron calibration constants and does not require the determination of any parameters by a minimization technique. Thus, this technique lends itself to fast energy reconstruction in a first level trigger. The reconstructed mean values of the hadron energies are within \\pm1% of the true values and the fractional energy resolution is [(58\\pm 3)%{\\sqrt{GeV}}/\\sqrt{E}+(2.5\\pm0.3)%]\\bigoplus(1.7\\pm0.2) GeV/E. The value of the e/h ratio obtained for the electromagnetic compartment of the combined calorimeter is 1.74\\pm0.04. Results of a study of the longitudinal hadronic shower development are also presented.

  20. A simple non-parametric goodness-of-fit test for elliptical copulas

    Directory of Open Access Journals (Sweden)

    Jaser Miriam

    2017-12-01

    Full Text Available In this paper, we propose a simple non-parametric goodness-of-fit test for elliptical copulas of any dimension. It is based on the equality of Kendall’s tau and Blomqvist’s beta for all bivariate margins. Nominal level and power of the proposed test are investigated in a Monte Carlo study. An empirical application illustrates our goodness-of-fit test at work.

  1. Comparison of statistical and clinical predictions of functional outcome after ischemic stroke.

    Directory of Open Access Journals (Sweden)

    Douglas D Thompson

    Full Text Available To determine whether the predictions of functional outcome after ischemic stroke made at the bedside using a doctor's clinical experience were more or less accurate than the predictions made by clinical prediction models (CPMs.A prospective cohort study of nine hundred and thirty one ischemic stroke patients recruited consecutively at the outpatient, inpatient and emergency departments of the Western General Hospital, Edinburgh between 2002 and 2005. Doctors made informal predictions of six month functional outcome on the Oxford Handicap Scale (OHS. Patients were followed up at six months with a validated postal questionnaire. For each patient we calculated the absolute predicted risk of death or dependence (OHS≥3 using five previously described CPMs. The specificity of a doctor's informal predictions of OHS≥3 at six months was good 0.96 (95% CI: 0.94 to 0.97 and similar to CPMs (range 0.94 to 0.96; however the sensitivity of both informal clinical predictions 0.44 (95% CI: 0.39 to 0.49 and clinical prediction models (range 0.38 to 0.45 was poor. The prediction of the level of disability after stroke was similar for informal clinical predictions (ordinal c-statistic 0.74 with 95% CI 0.72 to 0.76 and CPMs (range 0.69 to 0.75. No patient or clinician characteristic affected the accuracy of informal predictions, though predictions were more accurate in outpatients.CPMs are at least as good as informal clinical predictions in discriminating between good and bad functional outcome after ischemic stroke. The place of these models in clinical practice has yet to be determined.

  2. Non-parametric Tuning of PID Controllers A Modified Relay-Feedback-Test Approach

    CERN Document Server

    Boiko, Igor

    2013-01-01

    The relay feedback test (RFT) has become a popular and efficient  tool used in process identification and automatic controller tuning. Non-parametric Tuning of PID Controllers couples new modifications of classical RFT with application-specific optimal tuning rules to form a non-parametric method of test-and-tuning. Test and tuning are coordinated through a set of common parameters so that a PID controller can obtain the desired gain or phase margins in a system exactly, even with unknown process dynamics. The concept of process-specific optimal tuning rules in the nonparametric setup, with corresponding tuning rules for flow, level pressure, and temperature control loops is presented in the text.   Common problems of tuning accuracy based on parametric and non-parametric approaches are addressed. In addition, the text treats the parametric approach to tuning based on the modified RFT approach and the exact model of oscillations in the system under test using the locus of a perturbedrelay system (LPRS) meth...

  3. A Comparison of Parametric and Non-Parametric Methods Applied to a Likert Scale.

    Science.gov (United States)

    Mircioiu, Constantin; Atkinson, Jeffrey

    2017-05-10

    A trenchant and passionate dispute over the use of parametric versus non-parametric methods for the analysis of Likert scale ordinal data has raged for the past eight decades. The answer is not a simple "yes" or "no" but is related to hypotheses, objectives, risks, and paradigms. In this paper, we took a pragmatic approach. We applied both types of methods to the analysis of actual Likert data on responses from different professional subgroups of European pharmacists regarding competencies for practice. Results obtained show that with "large" (>15) numbers of responses and similar (but clearly not normal) distributions from different subgroups, parametric and non-parametric analyses give in almost all cases the same significant or non-significant results for inter-subgroup comparisons. Parametric methods were more discriminant in the cases of non-similar conclusions. Considering that the largest differences in opinions occurred in the upper part of the 4-point Likert scale (ranks 3 "very important" and 4 "essential"), a "score analysis" based on this part of the data was undertaken. This transformation of the ordinal Likert data into binary scores produced a graphical representation that was visually easier to understand as differences were accentuated. In conclusion, in this case of Likert ordinal data with high response rates, restraining the analysis to non-parametric methods leads to a loss of information. The addition of parametric methods, graphical analysis, analysis of subsets, and transformation of data leads to more in-depth analyses.

  4. Using multinomial and imprecise probability for non-parametric modelling of rainfall in Manizales (Colombia

    Directory of Open Access Journals (Sweden)

    Ibsen Chivatá Cárdenas

    2008-05-01

    Full Text Available This article presents a rainfall model constructed by applying non-parametric modelling and imprecise probabilities; these tools were used because there was not enough homogeneous information in the study area. The area’s hydro-logical information regarding rainfall was scarce and existing hydrological time series were not uniform. A distributed extended rainfall model was constructed from so-called probability boxes (p-boxes, multinomial probability distribu-tion and confidence intervals (a friendly algorithm was constructed for non-parametric modelling by combining the last two tools. This model confirmed the high level of uncertainty involved in local rainfall modelling. Uncertainty en-compassed the whole range (domain of probability values thereby showing the severe limitations on information, leading to the conclusion that a detailed estimation of probability would lead to significant error. Nevertheless, rele-vant information was extracted; it was estimated that maximum daily rainfall threshold (70 mm would be surpassed at least once every three years and the magnitude of uncertainty affecting hydrological parameter estimation. This paper’s conclusions may be of interest to non-parametric modellers and decisions-makers as such modelling and imprecise probability represents an alternative for hydrological variable assessment and maybe an obligatory proce-dure in the future. Its potential lies in treating scarce information and represents a robust modelling strategy for non-seasonal stochastic modelling conditions

  5. Robot Training With Vector Fields Based on Stroke Survivors' Individual Movement Statistics.

    Science.gov (United States)

    Wright, Zachary A; Lazzaro, Emily; Thielbar, Kelly O; Patton, James L; Huang, Felix C

    2018-02-01

    The wide variation in upper extremity motor impairments among stroke survivors necessitates more intelligent methods of customized therapy. However, current strategies for characterizing individual motor impairments are limited by the use of traditional clinical assessments (e.g., Fugl-Meyer) and simple engineering metrics (e.g., goal-directed performance). Our overall approach is to statistically identify the range of volitional movement capabilities, and then apply a robot-applied force vector field intervention that encourages under-expressed movements. We investigated whether explorative training with such customized force fields would improve stroke survivors' (n = 11) movement patterns in comparison to a control group that trained without forces (n = 11). Force and control groups increased Fugl-Meyer UE scores (average of 1.0 and 1.1, respectively), which is not considered clinically meaningful. Interestingly, participants from both groups demonstrated dramatic increases in their range of velocity during exploration following only six days of training (average increase of 166.4% and 153.7% for the Force and Control group, respectively). While both groups showed evidence of improvement, we also found evidence that customized forces affected learning in a systematic way. When customized forces were active, we observed broader distributions of velocity that were not present in the controls. Second, we found that these changes led to specific changes in unassisted motion. In addition, while the shape of movement distributions changed significantly for both groups, detailed analysis of the velocity distributions revealed that customized forces promoted a greater proportion of favorable changes. Taken together, these results provide encouraging evidence that patient-specific force fields based on individuals' movement statistics can be used to create new movement patterns and shape them in a customized manner. To the best of our knowledge, this paper is the first

  6. Stroke

    Science.gov (United States)

    ... adjust your treatment as needed. Rehabilitation After a stroke, you may need rehabilitation (rehab) to help you recover. Rehab may include working with speech, physical, and occupational therapists. Language, ... may have trouble communicating after a stroke. You may not be able to find the ...

  7. Tremor Detection Using Parametric and Non-Parametric Spectral Estimation Methods: A Comparison with Clinical Assessment.

    Science.gov (United States)

    Martinez Manzanera, Octavio; Elting, Jan Willem; van der Hoeven, Johannes H; Maurits, Natasha M

    2016-01-01

    In the clinic, tremor is diagnosed during a time-limited process in which patients are observed and the characteristics of tremor are visually assessed. For some tremor disorders, a more detailed analysis of these characteristics is needed. Accelerometry and electromyography can be used to obtain a better insight into tremor. Typically, routine clinical assessment of accelerometry and electromyography data involves visual inspection by clinicians and occasionally computational analysis to obtain objective characteristics of tremor. However, for some tremor disorders these characteristics may be different during daily activity. This variability in presentation between the clinic and daily life makes a differential diagnosis more difficult. A long-term recording of tremor by accelerometry and/or electromyography in the home environment could help to give a better insight into the tremor disorder. However, an evaluation of such recordings using routine clinical standards would take too much time. We evaluated a range of techniques that automatically detect tremor segments in accelerometer data, as accelerometer data is more easily obtained in the home environment than electromyography data. Time can be saved if clinicians only have to evaluate the tremor characteristics of segments that have been automatically detected in longer daily activity recordings. We tested four non-parametric methods and five parametric methods on clinical accelerometer data from 14 patients with different tremor disorders. The consensus between two clinicians regarding the presence or absence of tremor on 3943 segments of accelerometer data was employed as reference. The nine methods were tested against this reference to identify their optimal parameters. Non-parametric methods generally performed better than parametric methods on our dataset when optimal parameters were used. However, one parametric method, employing the high frequency content of the tremor bandwidth under consideration

  8. Non-parametric system identification from non-linear stochastic response

    DEFF Research Database (Denmark)

    Rüdinger, Finn; Krenk, Steen

    2001-01-01

    An estimation method is proposed for identification of non-linear stiffness and damping of single-degree-of-freedom systems under stationary white noise excitation. Non-parametric estimates of the stiffness and damping along with an estimate of the white noise intensity are obtained by suitable...... processing of records of the stochastic response. The stiffness estimation is based on a local iterative procedure, which compares the elastic energy at mean-level crossings with the kinetic energy at the extremes. The damping estimation is based on a generic expression for the probability density...

  9. A Comparison of Parametric and Non-Parametric Methods Applied to a Likert Scale

    OpenAIRE

    Mircioiu, Constantin; Atkinson, Jeffrey

    2017-01-01

    A trenchant and passionate dispute over the use of parametric versus non-parametric methods for the analysis of Likert scale ordinal data has raged for the past eight decades. The answer is not a simple “yes” or “no” but is related to hypotheses, objectives, risks, and paradigms. In this paper, we took a pragmatic approach. We applied both types of methods to the analysis of actual Likert data on responses from different professional subgroups of European pharmacists regarding competencies fo...

  10. Locally-Based Kernal PLS Smoothing to Non-Parametric Regression Curve Fitting

    Science.gov (United States)

    Rosipal, Roman; Trejo, Leonard J.; Wheeler, Kevin; Korsmeyer, David (Technical Monitor)

    2002-01-01

    We present a novel smoothing approach to non-parametric regression curve fitting. This is based on kernel partial least squares (PLS) regression in reproducing kernel Hilbert space. It is our concern to apply the methodology for smoothing experimental data where some level of knowledge about the approximate shape, local inhomogeneities or points where the desired function changes its curvature is known a priori or can be derived based on the observed noisy data. We propose locally-based kernel PLS regression that extends the previous kernel PLS methodology by incorporating this knowledge. We compare our approach with existing smoothing splines, hybrid adaptive splines and wavelet shrinkage techniques on two generated data sets.

  11. Efficiency Analysis with non parametric method: Illustration of the Tunisian ports

    OpenAIRE

    Hlali Arbia

    2018-01-01

    This paper applies a non-parametric method to provide level technical efficiency for 7 Tunisian ports during 18 years (1998-2015). These ports represent different data set. The use of the model of variable returns to scale (VRS) has led to interesting results. The results show that the most ports are characterized by low levels of technical efficiency, with the exception port of Rades. In addition, the result shows the variation of variable returns to scale and constant returns to scale of te...

  12. Combined non-parametric and parametric approach for identification of time-variant systems

    Science.gov (United States)

    Dziedziech, Kajetan; Czop, Piotr; Staszewski, Wieslaw J.; Uhl, Tadeusz

    2018-03-01

    Identification of systems, structures and machines with variable physical parameters is a challenging task especially when time-varying vibration modes are involved. The paper proposes a new combined, two-step - i.e. non-parametric and parametric - modelling approach in order to determine time-varying vibration modes based on input-output measurements. Single-degree-of-freedom (SDOF) vibration modes from multi-degree-of-freedom (MDOF) non-parametric system representation are extracted in the first step with the use of time-frequency wavelet-based filters. The second step involves time-varying parametric representation of extracted modes with the use of recursive linear autoregressive-moving-average with exogenous inputs (ARMAX) models. The combined approach is demonstrated using system identification analysis based on the experimental mass-varying MDOF frame-like structure subjected to random excitation. The results show that the proposed combined method correctly captures the dynamics of the analysed structure, using minimum a priori information on the model.

  13. A Bayesian non-parametric Potts model with application to pre-surgical FMRI data.

    Science.gov (United States)

    Johnson, Timothy D; Liu, Zhuqing; Bartsch, Andreas J; Nichols, Thomas E

    2013-08-01

    The Potts model has enjoyed much success as a prior model for image segmentation. Given the individual classes in the model, the data are typically modeled as Gaussian random variates or as random variates from some other parametric distribution. In this article, we present a non-parametric Potts model and apply it to a functional magnetic resonance imaging study for the pre-surgical assessment of peritumoral brain activation. In our model, we assume that the Z-score image from a patient can be segmented into activated, deactivated, and null classes, or states. Conditional on the class, or state, the Z-scores are assumed to come from some generic distribution which we model non-parametrically using a mixture of Dirichlet process priors within the Bayesian framework. The posterior distribution of the model parameters is estimated with a Markov chain Monte Carlo algorithm, and Bayesian decision theory is used to make the final classifications. Our Potts prior model includes two parameters, the standard spatial regularization parameter and a parameter that can be interpreted as the a priori probability that each voxel belongs to the null, or background state, conditional on the lack of spatial regularization. We assume that both of these parameters are unknown, and jointly estimate them along with other model parameters. We show through simulation studies that our model performs on par, in terms of posterior expected loss, with parametric Potts models when the parametric model is correctly specified and outperforms parametric models when the parametric model in misspecified.

  14. Non-parametric transformation for data correlation and integration: From theory to practice

    Energy Technology Data Exchange (ETDEWEB)

    Datta-Gupta, A.; Xue, Guoping; Lee, Sang Heon [Texas A& M Univ., College Station, TX (United States)

    1997-08-01

    The purpose of this paper is two-fold. First, we introduce the use of non-parametric transformations for correlating petrophysical data during reservoir characterization. Such transformations are completely data driven and do not require a priori functional relationship between response and predictor variables which is the case with traditional multiple regression. The transformations are very general, computationally efficient and can easily handle mixed data types for example, continuous variables such as porosity, permeability and categorical variables such as rock type, lithofacies. The power of the non-parametric transformation techniques for data correlation has been illustrated through synthetic and field examples. Second, we utilize these transformations to propose a two-stage approach for data integration during heterogeneity characterization. The principal advantages of our approach over traditional cokriging or cosimulation methods are: (1) it does not require a linear relationship between primary and secondary data, (2) it exploits the secondary information to its fullest potential by maximizing the correlation between the primary and secondary data, (3) it can be easily applied to cases where several types of secondary or soft data are involved, and (4) it significantly reduces variance function calculations and thus, greatly facilitates non-Gaussian cosimulation. We demonstrate the data integration procedure using synthetic and field examples. The field example involves estimation of pore-footage distribution using well data and multiple seismic attributes.

  15. Non-parametric genetic prediction of complex traits with latent Dirichlet process regression models.

    Science.gov (United States)

    Zeng, Ping; Zhou, Xiang

    2017-09-06

    Using genotype data to perform accurate genetic prediction of complex traits can facilitate genomic selection in animal and plant breeding programs, and can aid in the development of personalized medicine in humans. Because most complex traits have a polygenic architecture, accurate genetic prediction often requires modeling all genetic variants together via polygenic methods. Here, we develop such a polygenic method, which we refer to as the latent Dirichlet process regression model. Dirichlet process regression is non-parametric in nature, relies on the Dirichlet process to flexibly and adaptively model the effect size distribution, and thus enjoys robust prediction performance across a broad spectrum of genetic architectures. We compare Dirichlet process regression with several commonly used prediction methods with simulations. We further apply Dirichlet process regression to predict gene expressions, to conduct PrediXcan based gene set test, to perform genomic selection of four traits in two species, and to predict eight complex traits in a human cohort.Genetic prediction of complex traits with polygenic architecture has wide application from animal breeding to disease prevention. Here, Zeng and Zhou develop a non-parametric genetic prediction method based on latent Dirichlet Process regression models.

  16. A web application for evaluating Phase I methods using a non-parametric optimal benchmark.

    Science.gov (United States)

    Wages, Nolan A; Varhegyi, Nikole

    2017-10-01

    In evaluating the performance of Phase I dose-finding designs, simulation studies are typically conducted to assess how often a method correctly selects the true maximum tolerated dose under a set of assumed dose-toxicity curves. A necessary component of the evaluation process is to have some concept for how well a design can possibly perform. The notion of an upper bound on the accuracy of maximum tolerated dose selection is often omitted from the simulation study, and the aim of this work is to provide researchers with accessible software to quickly evaluate the operating characteristics of Phase I methods using a benchmark. The non-parametric optimal benchmark is a useful theoretical tool for simulations that can serve as an upper limit for the accuracy of maximum tolerated dose identification based on a binary toxicity endpoint. It offers researchers a sense of the plausibility of a Phase I method's operating characteristics in simulation. We have developed an R shiny web application for simulating the benchmark. The web application has the ability to quickly provide simulation results for the benchmark and requires no programming knowledge. The application is free to access and use on any device with an Internet browser. The application provides the percentage of correct selection of the maximum tolerated dose and an accuracy index, operating characteristics typically used in evaluating the accuracy of dose-finding designs. We hope this software will facilitate the use of the non-parametric optimal benchmark as an evaluation tool in dose-finding simulation.

  17. Cliff´s Delta Calculator: A non-parametric effect size program for two groups of observations

    Directory of Open Access Journals (Sweden)

    Guillermo Macbeth

    2011-05-01

    Full Text Available The Cliff´s Delta statistic is an effect size measure that quantifies the amount of difference between two non-parametric variables beyond p-values interpretation. This measure can be understood as a useful complementary analysis for the corresponding hypothesis testing. During the last two decades the use of effect size measures has been strongly encouraged by methodologists and leading institutions of behavioral sciences. The aim of this contribution is to introduce the Cliff´s Delta Calculator software that performs such analysis and offers some interpretation tips. Differences and similarities with the parametric case are analysed and illustrated. The implementation of this free program is fully described and compared with other calculators. Alternative algorithmic approaches are mathematically analysed and a basic linear algebra proof of its equivalence is formally presented. Two worked examples in cognitive psychology are commented. A visual interpretation of Cliff´s Delta is suggested. Availability, installation and applications of the program are presented and discussed.

  18. Statistical Inference for Fractional Diffusion Processes

    CERN Document Server

    Rao, B L S Prakasa

    2010-01-01

    Statistical Inference for Fractional Diffusion Processes looks at statistical inference for stochastic processes modeled by stochastic differential equations driven by fractional Brownian motion. Other related processes, such as sequential inference, nonparametric and non parametric inference and parametric estimation are also discussed. The book will deal with Fractional Diffusion Processes (FDP) in relation to statistical influence for stochastic processes. The books main focus is on parametric and non parametric inference problems for fractional diffusion processes when a complete path of t

  19. On the SU(2 vertical stroke 1) WZNW model and its statistical mechanics applications

    Energy Technology Data Exchange (ETDEWEB)

    Saleur, H. [CEA Centre d' Etudes de Saclay, 91 - Gif-sur-Yvette (France). Service de Physique Theorique]|[University of Southern California, Los Angeles, CA (United States). Dept. of Physics; Schomerus, V. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)

    2006-11-15

    Motivated by a careful analysis of the Laplacian on the supergroup SU(2 vertical stroke 1) we formulate a proposal for the state space of the SU(2 vertical stroke 1) WZNW model. We then use properties of sl(2 vertical stroke 1) characters to compute the partition function of the theory. In the special case of level k=1 the latter is found to agree with the properly regularized partition function for the continuum limit of the integrable sl(2 vertical stroke 1)3- anti 3 super-spin chain. Some general conclusions applicable to other WZNW models (in particular the case k=-1/2) are also drawn. (orig.)

  20. Non-parametric co-clustering of large scale sparse bipartite networks on the GPU

    DEFF Research Database (Denmark)

    Hansen, Toke Jansen; Mørup, Morten; Hansen, Lars Kai

    2011-01-01

    Co-clustering is a problem of both theoretical and practical importance, e.g., market basket analysis and collaborative filtering, and in web scale text processing. We state the co-clustering problem in terms of non-parametric generative models which can address the issue of estimating the number...... of row and column clusters from a hypothesis space of an infinite number of clusters. To reach large scale applications of co-clustering we exploit that parameter inference for co-clustering is well suited for parallel computing. We develop a generic GPU framework for efficient inference on large scale......-life large scale collaborative filtering data and web scale text corpora, demonstrating that latent mesoscale structures extracted by the co-clustering problem as formulated by the Infinite Relational Model (IRM) are consistent across consecutive runs with different initializations and also relevant...

  1. Comparative Study of Parametric and Non-parametric Approaches in Fault Detection and Isolation

    DEFF Research Database (Denmark)

    Katebi, S.D.; Blanke, M.; Katebi, M.R.

    This report describes a comparative study between two approaches to fault detection and isolation in dynamic systems. The first approach uses a parametric model of the system. The main components of such techniques are residual and signature generation for processing and analyzing. The second app...... algorithms employed are adopted from the template matching in pattern recognition. Extensive simulation studies are performed to demonstrate satisfactory performance of the proposed techniques. The advantages and disadvantages of each approach are discussed and analyzed....... approach is non-parametric in the sense that the signature analysis is only dependent on the frequency or time domain information extracted directly from the input-output signals. Based on these approaches, two different fault monitoring schemes are developed where the feature extraction and fault decision...

  2. Bootstrap Prediction Intervals in Non-Parametric Regression with Applications to Anomaly Detection

    Science.gov (United States)

    Kumar, Sricharan; Srivistava, Ashok N.

    2012-01-01

    Prediction intervals provide a measure of the probable interval in which the outputs of a regression model can be expected to occur. Subsequently, these prediction intervals can be used to determine if the observed output is anomalous or not, conditioned on the input. In this paper, a procedure for determining prediction intervals for outputs of nonparametric regression models using bootstrap methods is proposed. Bootstrap methods allow for a non-parametric approach to computing prediction intervals with no specific assumptions about the sampling distribution of the noise or the data. The asymptotic fidelity of the proposed prediction intervals is theoretically proved. Subsequently, the validity of the bootstrap based prediction intervals is illustrated via simulations. Finally, the bootstrap prediction intervals are applied to the problem of anomaly detection on aviation data.

  3. Non-parametric Estimation of a Survival Function with Two-stage Design Studies.

    Science.gov (United States)

    Li, Gang; Tseng, Chi-Hong

    2008-06-01

    The two-stage design is popular in epidemiology studies and clinical trials due to its cost effectiveness. Typically, the first stage sample contains cheaper and possibly biased information, while the second stage validation sample consists of a subset of subjects with accurate and complete information. In this paper, we study estimation of a survival function with right-censored survival data from a two-stage design. A non-parametric estimator is derived by combining data from both stages. We also study its large sample properties and derive pointwise and simultaneous confidence intervals for the survival function. The proposed estimator effectively reduces the variance and finite-sample bias of the Kaplan-Meier estimator solely based on the second stage validation sample. Finally, we apply our method to a real data set from a medical device post-marketing surveillance study.

  4. Non-parametric classification of esophagus motility by means of neural networks

    DEFF Research Database (Denmark)

    Thøgersen, C; Rasmussen, C; Rutz, K

    1997-01-01

    Automatic long-term recording of esophageal pressures by means of intraluminal transducers is used increasingly for evaluation of esophageal function. Most automatic analysis techniques are based on detection of derived parameters from the time series by means of arbitrary rule-based criterions....... The aim of the present work has been to test the ability of neural networks to identify abnormal contraction patterns in patients with non-obstructive dysphagia (NOBD). Nineteen volunteers and 22 patients with NOBD underwent simultaneous recordings of four pressures in the esophagus for at least 23 hours....... Data from 21 subjects were selected for training. The performances of two trained networks were subsequently verified on reference data from 20 subjects. The results show that non-parametric classification by means of neural networks has good potentials. Back propagation shows good performance...

  5. A non-parametric consistency test of the ΛCDM model with Planck CMB data

    Energy Technology Data Exchange (ETDEWEB)

    Aghamousa, Amir; Shafieloo, Arman [Korea Astronomy and Space Science Institute, Daejeon 305-348 (Korea, Republic of); Hamann, Jan, E-mail: amir@aghamousa.com, E-mail: jan.hamann@unsw.edu.au, E-mail: shafieloo@kasi.re.kr [School of Physics, The University of New South Wales, Sydney NSW 2052 (Australia)

    2017-09-01

    Non-parametric reconstruction methods, such as Gaussian process (GP) regression, provide a model-independent way of estimating an underlying function and its uncertainty from noisy data. We demonstrate how GP-reconstruction can be used as a consistency test between a given data set and a specific model by looking for structures in the residuals of the data with respect to the model's best-fit. Applying this formalism to the Planck temperature and polarisation power spectrum measurements, we test their global consistency with the predictions of the base ΛCDM model. Our results do not show any serious inconsistencies, lending further support to the interpretation of the base ΛCDM model as cosmology's gold standard.

  6. Performance of non-parametric algorithms for spatial mapping of tropical forest structure

    Directory of Open Access Journals (Sweden)

    Liang Xu

    2016-08-01

    Full Text Available Abstract Background Mapping tropical forest structure is a critical requirement for accurate estimation of emissions and removals from land use activities. With the availability of a wide range of remote sensing imagery of vegetation characteristics from space, development of finer resolution and more accurate maps has advanced in recent years. However, the mapping accuracy relies heavily on the quality of input layers, the algorithm chosen, and the size and quality of inventory samples for calibration and validation. Results By using airborne lidar data as the “truth” and focusing on the mean canopy height (MCH as a key structural parameter, we test two commonly-used non-parametric techniques of maximum entropy (ME and random forest (RF for developing maps over a study site in Central Gabon. Results of mapping show that both approaches have improved accuracy with more input layers in mapping canopy height at 100 m (1-ha pixels. The bias-corrected spatial models further improve estimates for small and large trees across the tails of height distributions with a trade-off in increasing overall mean squared error that can be readily compensated by increasing the sample size. Conclusions A significant improvement in tropical forest mapping can be achieved by weighting the number of inventory samples against the choice of image layers and the non-parametric algorithms. Without future satellite observations with better sensitivity to forest biomass, the maps based on existing data will remain slightly biased towards the mean of the distribution and under and over estimating the upper and lower tails of the distribution.

  7. Proposing a framework for airline service quality evaluation using Type-2 Fuzzy TOPSIS and non-parametric analysis

    Directory of Open Access Journals (Sweden)

    Navid Haghighat

    2017-12-01

    Full Text Available This paper focuses on evaluating airline service quality from the perspective of passengers' view. Until now a lot of researches has been performed in airline service quality evaluation in the world but a little research has been conducted in Iran, yet. In this study, a framework for measuring airline service quality in Iran is proposed. After reviewing airline service quality criteria, SSQAI model was selected because of its comprehensiveness in covering airline service quality dimensions. SSQAI questionnaire items were redesigned to adopt with Iranian airlines requirements and environmental circumstances in the Iran's economic and cultural context. This study includes fuzzy decision-making theory, considering the possible fuzzy subjective judgment of the evaluators during airline service quality evaluation. Fuzzy TOPSIS have been applied for ranking airlines service quality performances. Three major Iranian airlines which have the most passenger transfer volumes in domestic and foreign flights were chosen for evaluation in this research. Results demonstrated Mahan airline has got the best service quality performance rank in gaining passengers' satisfaction with delivery of high-quality services to its passengers, among the three major Iranian airlines. IranAir and Aseman airlines placed in the second and third rank, respectively, according to passenger's evaluation. Statistical analysis has been used in analyzing passenger responses. Due to the abnormality of data, Non-parametric tests were applied. To demonstrate airline ranks in every criterion separately, Friedman test was performed. Variance analysis and Tukey test were applied to study the influence of increasing in age and educational level of passengers on degree of their satisfaction from airline's service quality. Results showed that age has no significant relation to passenger satisfaction of airlines, however, increasing in educational level demonstrated a negative impact on

  8. Transit Timing Observations from Kepler: II. Confirmation of Two Multiplanet Systems via a Non-parametric Correlation Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Ford, Eric B.; /Florida U.; Fabrycky, Daniel C.; /Lick Observ.; Steffen, Jason H.; /Fermilab; Carter, Joshua A.; /Harvard-Smithsonian Ctr. Astrophys.; Fressin, Francois; /Harvard-Smithsonian Ctr. Astrophys.; Holman, Matthew J.; /Harvard-Smithsonian Ctr. Astrophys.; Lissauer, Jack J.; /NASA, Ames; Moorhead, Althea V.; /Florida U.; Morehead, Robert C.; /Florida U.; Ragozzine, Darin; /Harvard-Smithsonian Ctr. Astrophys.; Rowe, Jason F.; /NASA, Ames /SETI Inst., Mtn. View /San Diego State U., Astron. Dept.

    2012-01-01

    We present a new method for confirming transiting planets based on the combination of transit timing variations (TTVs) and dynamical stability. Correlated TTVs provide evidence that the pair of bodies are in the same physical system. Orbital stability provides upper limits for the masses of the transiting companions that are in the planetary regime. This paper describes a non-parametric technique for quantifying the statistical significance of TTVs based on the correlation of two TTV data sets. We apply this method to an analysis of the transit timing variations of two stars with multiple transiting planet candidates identified by Kepler. We confirm four transiting planets in two multiple planet systems based on their TTVs and the constraints imposed by dynamical stability. An additional three candidates in these same systems are not confirmed as planets, but are likely to be validated as real planets once further observations and analyses are possible. If all were confirmed, these systems would be near 4:6:9 and 2:4:6:9 period commensurabilities. Our results demonstrate that TTVs provide a powerful tool for confirming transiting planets, including low-mass planets and planets around faint stars for which Doppler follow-up is not practical with existing facilities. Continued Kepler observations will dramatically improve the constraints on the planet masses and orbits and provide sensitivity for detecting additional non-transiting planets. If Kepler observations were extended to eight years, then a similar analysis could likely confirm systems with multiple closely spaced, small transiting planets in or near the habitable zone of solar-type stars.

  9. TRANSIT TIMING OBSERVATIONS FROM KEPLER. II. CONFIRMATION OF TWO MULTIPLANET SYSTEMS VIA A NON-PARAMETRIC CORRELATION ANALYSIS

    International Nuclear Information System (INIS)

    Ford, Eric B.; Moorhead, Althea V.; Morehead, Robert C.; Fabrycky, Daniel C.; Steffen, Jason H.; Carter, Joshua A.; Fressin, Francois; Holman, Matthew J.; Ragozzine, Darin; Charbonneau, David; Lissauer, Jack J.; Rowe, Jason F.; Borucki, William J.; Bryson, Stephen T.; Burke, Christopher J.; Caldwell, Douglas A.; Welsh, William F.; Allen, Christopher; Batalha, Natalie M.; Buchhave, Lars A.

    2012-01-01

    We present a new method for confirming transiting planets based on the combination of transit timing variations (TTVs) and dynamical stability. Correlated TTVs provide evidence that the pair of bodies is in the same physical system. Orbital stability provides upper limits for the masses of the transiting companions that are in the planetary regime. This paper describes a non-parametric technique for quantifying the statistical significance of TTVs based on the correlation of two TTV data sets. We apply this method to an analysis of the TTVs of two stars with multiple transiting planet candidates identified by Kepler. We confirm four transiting planets in two multiple-planet systems based on their TTVs and the constraints imposed by dynamical stability. An additional three candidates in these same systems are not confirmed as planets, but are likely to be validated as real planets once further observations and analyses are possible. If all were confirmed, these systems would be near 4:6:9 and 2:4:6:9 period commensurabilities. Our results demonstrate that TTVs provide a powerful tool for confirming transiting planets, including low-mass planets and planets around faint stars for which Doppler follow-up is not practical with existing facilities. Continued Kepler observations will dramatically improve the constraints on the planet masses and orbits and provide sensitivity for detecting additional non-transiting planets. If Kepler observations were extended to eight years, then a similar analysis could likely confirm systems with multiple closely spaced, small transiting planets in or near the habitable zone of solar-type stars.

  10. Visual MRI: merging information visualization and non-parametric clustering techniques for MRI dataset analysis.

    Science.gov (United States)

    Castellani, Umberto; Cristani, Marco; Combi, Carlo; Murino, Vittorio; Sbarbati, Andrea; Marzola, Pasquina

    2008-11-01

    This paper presents Visual MRI, an innovative tool for the magnetic resonance imaging (MRI) analysis of tumoral tissues. The main goal of the analysis is to separate each magnetic resonance image in meaningful clusters, highlighting zones which are more probably related with the cancer evolution. Such non-invasive analysis serves to address novel cancer treatments, resulting in a less destabilizing and more effective type of therapy than the chemotherapy-based ones. The advancements brought by Visual MRI are two: first, it is an integration of effective information visualization (IV) techniques into a clustering framework, which separates each MRI image in a set of informative clusters; the second improvement relies in the clustering framework itself, which is derived from a recently re-discovered non-parametric grouping strategy, i.e., the mean shift. The proposed methodology merges visualization methods and data mining techniques, providing a computational framework that allows the physician to move effectively from the MRI image to the images displaying the derived parameter space. An unsupervised non-parametric clustering algorithm, derived from the mean shift paradigm, and called MRI-mean shift, is the novel data mining technique proposed here. The main underlying idea of such approach is that the parameter space is regarded as an empirical probability density function to estimate: the possible separate modes and their attraction basins represent separated clusters. The mean shift algorithm needs sensibility threshold values to be set, which could lead to highly different segmentation results. Usually, these values are set by hands. Here, with the MRI-mean shift algorithm, we propose a strategy based on a structured optimality criterion which faces effectively this issue, resulting in a completely unsupervised clustering framework. A linked brushing visualization technique is then used for representing clusters on the parameter space and on the MRI image

  11. Further Empirical Results on Parametric Versus Non-Parametric IRT Modeling of Likert-Type Personality Data

    Science.gov (United States)

    Maydeu-Olivares, Albert

    2005-01-01

    Chernyshenko, Stark, Chan, Drasgow, and Williams (2001) investigated the fit of Samejima's logistic graded model and Levine's non-parametric MFS model to the scales of two personality questionnaires and found that the graded model did not fit well. We attribute the poor fit of the graded model to small amounts of multidimensionality present in…

  12. Non-parametric study on the optimization of thorium content in a 54-element fuel bundle for use in a CANDU-SCWR

    International Nuclear Information System (INIS)

    Hummel, D.W.; Novog, D.R.

    2011-01-01

    A new 54-element fuel bundle design has been proposed for use in a Supercritical Water-Cooled Reactor, a conceptual evolution of existing CANDU reactors. Pursuant to the goals of the Generation IV International Forum, specifically regarding advancement in fuel cycles, the feasibility of optimizing the thorium content within each ring of fuel elements has been studied. 864 unique permutations of thorium and uranium content were modeled with WIMS-AECL, and the results were analyzed using non-parametric statistical methods. Key findings include that discharge burnup and coolant void reactivity are inversely related to the total thorium content in the bundle, and that the maximum linear rating and form factor are inversely related to the thorium content in the outermost ring of fuel elements. (author)

  13. Experimental Sentinel-2 LAI estimation using parametric, non-parametric and physical retrieval methods - A comparison

    Science.gov (United States)

    Verrelst, Jochem; Rivera, Juan Pablo; Veroustraete, Frank; Muñoz-Marí, Jordi; Clevers, Jan G. P. W.; Camps-Valls, Gustau; Moreno, José

    2015-10-01

    Given the forthcoming availability of Sentinel-2 (S2) images, this paper provides a systematic comparison of retrieval accuracy and processing speed of a multitude of parametric, non-parametric and physically-based retrieval methods using simulated S2 data. An experimental field dataset (SPARC), collected at the agricultural site of Barrax (Spain), was used to evaluate different retrieval methods on their ability to estimate leaf area index (LAI). With regard to parametric methods, all possible band combinations for several two-band and three-band index formulations and a linear regression fitting function have been evaluated. From a set of over ten thousand indices evaluated, the best performing one was an optimized three-band combination according to (ρ560 -ρ1610 -ρ2190) / (ρ560 +ρ1610 +ρ2190) with a 10-fold cross-validation RCV2 of 0.82 (RMSECV : 0.62). This family of methods excel for their fast processing speed, e.g., 0.05 s to calibrate and validate the regression function, and 3.8 s to map a simulated S2 image. With regard to non-parametric methods, 11 machine learning regression algorithms (MLRAs) have been evaluated. This methodological family has the advantage of making use of the full optical spectrum as well as flexible, nonlinear fitting. Particularly kernel-based MLRAs lead to excellent results, with variational heteroscedastic (VH) Gaussian Processes regression (GPR) as the best performing method, with a RCV2 of 0.90 (RMSECV : 0.44). Additionally, the model is trained and validated relatively fast (1.70 s) and the processed image (taking 73.88 s) includes associated uncertainty estimates. More challenging is the inversion of a PROSAIL based radiative transfer model (RTM). After the generation of a look-up table (LUT), a multitude of cost functions and regularization options were evaluated. The best performing cost function is Pearson's χ -square. It led to a R2 of 0.74 (RMSE: 0.80) against the validation dataset. While its validation went fast

  14. Depth estimation from multi-scale SLIC superpixels using non-parametric learning

    Science.gov (United States)

    Jiang, Yifeng; Zhu, Yuesheng; Qing, Yin; Yang, Fan

    2017-07-01

    This study introduces a novel depth estimation method that can automatically generate plausible depth map from a single image with unstructured environment. Our goal is to extrapolate depth map with more correct, rich, and distinct depth order, which is both quantitatively accurate as well as visually pleasing. Based on the preexisting DepthTransfer algorithm, our approach primarily transfers depth information at the level of superpixels from the most photometrically similar retrieval images under the framework of non-parametric learning. Posteriorly, we propose to concurrently warp the corresponding superpixels in multi-scale levels, where we employ an improved SLIC technique to segment the RGBD images from coarse to fine. Then, modified Cross Bilateral Filter is leveraged to refine the final depth field. With respect to training and evaluation, we perform our experiment on the popular Make3D dataset and demonstrate that our method outperforms the state-of-the-art in both efficacy and computational efficiency. Especially, the final results show that in qualitatively evaluation, our results are visually superior in realism and simultaneously more immersive.

  15. Modeling the World Health Organization Disability Assessment Schedule II using non-parametric item response models.

    Science.gov (United States)

    Galindo-Garre, Francisca; Hidalgo, María Dolores; Guilera, Georgina; Pino, Oscar; Rojo, J Emilio; Gómez-Benito, Juana

    2015-03-01

    The World Health Organization Disability Assessment Schedule II (WHO-DAS II) is a multidimensional instrument developed for measuring disability. It comprises six domains (getting around, self-care, getting along with others, life activities and participation in society). The main purpose of this paper is the evaluation of the psychometric properties for each domain of the WHO-DAS II with parametric and non-parametric Item Response Theory (IRT) models. A secondary objective is to assess whether the WHO-DAS II items within each domain form a hierarchy of invariantly ordered severity indicators of disability. A sample of 352 patients with a schizophrenia spectrum disorder is used in this study. The 36 items WHO-DAS II was administered during the consultation. Partial Credit and Mokken scale models are used to study the psychometric properties of the questionnaire. The psychometric properties of the WHO-DAS II scale are satisfactory for all the domains. However, we identify a few items that do not discriminate satisfactorily between different levels of disability and cannot be invariantly ordered in the scale. In conclusion the WHO-DAS II can be used to assess overall disability in patients with schizophrenia, but some domains are too general to assess functionality in these patients because they contain items that are not applicable to this pathology. Copyright © 2014 John Wiley & Sons, Ltd.

  16. Design Automation Using Script Languages. High-Level CAD Templates in Non-Parametric Programs

    Science.gov (United States)

    Moreno, R.; Bazán, A. M.

    2017-10-01

    The main purpose of this work is to study the advantages offered by the application of traditional techniques of technical drawing in processes for automation of the design, with non-parametric CAD programs, provided with scripting languages. Given that an example drawing can be solved with traditional step-by-step detailed procedures, is possible to do the same with CAD applications and to generalize it later, incorporating references. In today’s modern CAD applications, there are striking absences of solutions for building engineering: oblique projections (military and cavalier), 3D modelling of complex stairs, roofs, furniture, and so on. The use of geometric references (using variables in script languages) and their incorporation into high-level CAD templates allows the automation of processes. Instead of repeatedly creating similar designs or modifying their data, users should be able to use these templates to generate future variations of the same design. This paper presents the automation process of several complex drawing examples based on CAD script files aided with parametric geometry calculation tools. The proposed method allows us to solve complex geometry designs not currently incorporated in the current CAD applications and to subsequently create other new derivatives without user intervention. Automation in the generation of complex designs not only saves time but also increases the quality of the presentations and reduces the possibility of human errors.

  17. A Non-Parametric Delphi Approach to Foster Innovation Policy Debate in Spain

    Directory of Open Access Journals (Sweden)

    Juan Carlos Salazar-Elena

    2016-05-01

    Full Text Available The aim of this paper is to identify some changes needed in Spain’s innovation policy to fill the gap between its innovation results and those of other European countries in lieu of sustainable leadership. To do this we apply the Delphi methodology to experts from academia, business, and government. To overcome the shortcomings of traditional descriptive methods, we develop an inferential analysis by following a non-parametric bootstrap method which enables us to identify important changes that should be implemented. Particularly interesting is the support found for improving the interconnections among the relevant agents of the innovation system (instead of focusing exclusively in the provision of knowledge and technological inputs through R and D activities, or the support found for “soft” policy instruments aimed at providing a homogeneous framework to assess the innovation capabilities of firms (e.g., for funding purposes. Attention to potential innovators among small and medium enterprises (SMEs and traditional industries is particularly encouraged by experts.

  18. Two non-parametric methods for derivation of constraints from radiotherapy dose–histogram data

    International Nuclear Information System (INIS)

    Ebert, M A; Kennedy, A; Joseph, D J; Gulliford, S L; Buettner, F; Foo, K; Haworth, A; Denham, J W

    2014-01-01

    Dose constraints based on histograms provide a convenient and widely-used method for informing and guiding radiotherapy treatment planning. Methods of derivation of such constraints are often poorly described. Two non-parametric methods for derivation of constraints are described and investigated in the context of determination of dose-specific cut-points—values of the free parameter (e.g., percentage volume of the irradiated organ) which best reflect resulting changes in complication incidence. A method based on receiver operating characteristic (ROC) analysis and one based on a maximally-selected standardized rank sum are described and compared using rectal toxicity data from a prostate radiotherapy trial. Multiple test corrections are applied using a free step-down resampling algorithm, which accounts for the large number of tests undertaken to search for optimal cut-points and the inherent correlation between dose–histogram points. Both methods provide consistent significant cut-point values, with the rank sum method displaying some sensitivity to the underlying data. The ROC method is simple to implement and can utilize a complication atlas, though an advantage of the rank sum method is the ability to incorporate all complication grades without the need for grade dichotomization. (note)

  19. Analytic Hierarchy Process (AHP in Ranking Non-Parametric Stochastic Rainfall and Streamflow Models

    Directory of Open Access Journals (Sweden)

    Masengo Ilunga

    2015-08-01

    Full Text Available Analytic Hierarchy Process (AHP is used in the selection of categories of non-parametric stochastic models for hydrological data generation and its formulation is based on pairwise comparisons of models. These models or techniques are obtained from a recent study initiated by the Water Research Commission of South Africa (WRC and were compared predominantly based on their capability to extrapolate data beyond the range of historic hydrological data. The different categories of models involved in the selection process were: wavelet (A, reordering (B, K-nearest neighbor (C, kernel density (D and bootstrap (E. In the AHP formulation, criteria for the selection of techniques are: "ability for data to preserve historic characteristics", "ability to generate new hydrological data", "scope of applicability", "presence of negative data generated" and "user friendliness". The pairwise comparisons performed through AHP showed that the overall order of selection (ranking of models was D, C, A, B and C. The weights of these techniques were found to be 27.21%, 24.3 %, 22.15 %, 13.89 % and 11.80 % respectively. Hence, bootstrap category received the highest preference while nearest neighbor received the lowest preference when all selection criteria are taken into consideration.

  20. Trend Analysis of Pahang River Using Non-Parametric Analysis: Mann Kendalls Trend Test

    International Nuclear Information System (INIS)

    Nur Hishaam Sulaiman; Mohd Khairul Amri Kamarudin; Mohd Khairul Amri Kamarudin; Ahmad Dasuki Mustafa; Muhammad Azizi Amran; Fazureen Azaman; Ismail Zainal Abidin; Norsyuhada Hairoma

    2015-01-01

    Flood is common in Pahang especially during northeast monsoon season from November to February. Three river cross station: Lubuk Paku, Sg. Yap and Temerloh were selected as area of this study. The stream flow and water level data were gathered from DID record. Data set for this study were analysed by using non-parametric analysis, Mann-Kendall Trend Test. The results that obtained from stream flow and water level analysis indicate that there are positively significant trend for Lubuk Paku (0.001) and Sg. Yap (<0.0001) from 1972-2011 with the p-value < 0.05. Temerloh (0.178) data from 1963-2011 recorded no trend for stream flow parameter but negative trend for water level parameter. Hydrological pattern and trend are extremely affected by outside factors such as north east monsoon season that occurred in South China Sea and affected Pahang during November to March. There are other factors such as development and management of the areas which can be considered as factors affected the data and results. Hydrological Pattern is important to indicate the river trend such as stream flow and water level. It can be used as flood mitigation by local authorities. (author)

  1. An artificial neural network architecture for non-parametric visual odometry in wireless capsule endoscopy

    Science.gov (United States)

    Dimas, George; Iakovidis, Dimitris K.; Karargyris, Alexandros; Ciuti, Gastone; Koulaouzidis, Anastasios

    2017-09-01

    Wireless capsule endoscopy is a non-invasive screening procedure of the gastrointestinal (GI) tract performed with an ingestible capsule endoscope (CE) of the size of a large vitamin pill. Such endoscopes are equipped with a usually low-frame-rate color camera which enables the visualization of the GI lumen and the detection of pathologies. The localization of the commercially available CEs is performed in the 3D abdominal space using radio-frequency (RF) triangulation from external sensor arrays, in combination with transit time estimation. State-of-the-art approaches, such as magnetic localization, which have been experimentally proved more accurate than the RF approach, are still at an early stage. Recently, we have demonstrated that CE localization is feasible using solely visual cues and geometric models. However, such approaches depend on camera parameters, many of which are unknown. In this paper the authors propose a novel non-parametric visual odometry (VO) approach to CE localization based on a feed-forward neural network architecture. The effectiveness of this approach in comparison to state-of-the-art geometric VO approaches is validated using a robotic-assisted in vitro experimental setup.

  2. An artificial neural network architecture for non-parametric visual odometry in wireless capsule endoscopy

    International Nuclear Information System (INIS)

    Dimas, George; Iakovidis, Dimitris K; Karargyris, Alexandros; Ciuti, Gastone; Koulaouzidis, Anastasios

    2017-01-01

    Wireless capsule endoscopy is a non-invasive screening procedure of the gastrointestinal (GI) tract performed with an ingestible capsule endoscope (CE) of the size of a large vitamin pill. Such endoscopes are equipped with a usually low-frame-rate color camera which enables the visualization of the GI lumen and the detection of pathologies. The localization of the commercially available CEs is performed in the 3D abdominal space using radio-frequency (RF) triangulation from external sensor arrays, in combination with transit time estimation. State-of-the-art approaches, such as magnetic localization, which have been experimentally proved more accurate than the RF approach, are still at an early stage. Recently, we have demonstrated that CE localization is feasible using solely visual cues and geometric models. However, such approaches depend on camera parameters, many of which are unknown. In this paper the authors propose a novel non-parametric visual odometry (VO) approach to CE localization based on a feed-forward neural network architecture. The effectiveness of this approach in comparison to state-of-the-art geometric VO approaches is validated using a robotic-assisted in vitro experimental setup. (paper)

  3. Scene Parsing With Integration of Parametric and Non-Parametric Models.

    Science.gov (United States)

    Shuai, Bing; Zuo, Zhen; Wang, Gang; Wang, Bing

    2016-05-01

    We adopt convolutional neural networks (CNNs) to be our parametric model to learn discriminative features and classifiers for local patch classification. Based on the occurrence frequency distribution of classes, an ensemble of CNNs (CNN-Ensemble) are learned, in which each CNN component focuses on learning different and complementary visual patterns. The local beliefs of pixels are output by CNN-Ensemble. Considering that visually similar pixels are indistinguishable under local context, we leverage the global scene semantics to alleviate the local ambiguity. The global scene constraint is mathematically achieved by adding a global energy term to the labeling energy function, and it is practically estimated in a non-parametric framework. A large margin-based CNN metric learning method is also proposed for better global belief estimation. In the end, the integration of local and global beliefs gives rise to the class likelihood of pixels, based on which maximum marginal inference is performed to generate the label prediction maps. Even without any post-processing, we achieve the state-of-the-art results on the challenging SiftFlow and Barcelona benchmarks.

  4. Two non-parametric methods for derivation of constraints from radiotherapy dose-histogram data

    Science.gov (United States)

    Ebert, M. A.; Gulliford, S. L.; Buettner, F.; Foo, K.; Haworth, A.; Kennedy, A.; Joseph, D. J.; Denham, J. W.

    2014-07-01

    Dose constraints based on histograms provide a convenient and widely-used method for informing and guiding radiotherapy treatment planning. Methods of derivation of such constraints are often poorly described. Two non-parametric methods for derivation of constraints are described and investigated in the context of determination of dose-specific cut-points—values of the free parameter (e.g., percentage volume of the irradiated organ) which best reflect resulting changes in complication incidence. A method based on receiver operating characteristic (ROC) analysis and one based on a maximally-selected standardized rank sum are described and compared using rectal toxicity data from a prostate radiotherapy trial. Multiple test corrections are applied using a free step-down resampling algorithm, which accounts for the large number of tests undertaken to search for optimal cut-points and the inherent correlation between dose-histogram points. Both methods provide consistent significant cut-point values, with the rank sum method displaying some sensitivity to the underlying data. The ROC method is simple to implement and can utilize a complication atlas, though an advantage of the rank sum method is the ability to incorporate all complication grades without the need for grade dichotomization.

  5. A Non-Parametric Item Response Theory Evaluation of the CAGE Instrument Among Older Adults.

    Science.gov (United States)

    Abdin, Edimansyah; Sagayadevan, Vathsala; Vaingankar, Janhavi Ajit; Picco, Louisa; Chong, Siow Ann; Subramaniam, Mythily

    2018-02-23

    The validity of the CAGE using item response theory (IRT) has not yet been examined in older adult population. This study aims to investigate the psychometric properties of the CAGE using both non-parametric and parametric IRT models, assess whether there is any differential item functioning (DIF) by age, gender and ethnicity and examine the measurement precision at the cut-off scores. We used data from the Well-being of the Singapore Elderly study to conduct Mokken scaling analysis (MSA), dichotomous Rasch and 2-parameter logistic IRT models. The measurement precision at the cut-off scores were evaluated using classification accuracy (CA) and classification consistency (CC). The MSA showed the overall scalability H index was 0.459, indicating a medium performing instrument. All items were found to be homogenous, measuring the same construct and able to discriminate well between respondents with high levels of the construct and the ones with lower levels. The item discrimination ranged from 1.07 to 6.73 while the item difficulty ranged from 0.33 to 2.80. Significant DIF was found for 2-item across ethnic group. More than 90% (CC and CA ranged from 92.5% to 94.3%) of the respondents were consistently and accurately classified by the CAGE cut-off scores of 2 and 3. The current study provides new evidence on the validity of the CAGE from the IRT perspective. This study provides valuable information of each item in the assessment of the overall severity of alcohol problem and the precision of the cut-off scores in older adult population.

  6. Non-Parametric Kinetic (NPK Analysis of Thermal Oxidation of Carbon Aerogels

    Directory of Open Access Journals (Sweden)

    Azadeh Seifi

    2017-05-01

    Full Text Available In recent years, much attention has been paid to aerogel materials (especially carbon aerogels due to their potential uses in energy-related applications, such as thermal energy storage and thermal protection systems. These open cell carbon-based porous materials (carbon aerogels can strongly react with oxygen at relatively low temperatures (~ 400°C. Therefore, it is necessary to evaluate the thermal performance of carbon aerogels in view of their energy-related applications at high temperatures and under thermal oxidation conditions. The objective of this paper is to study theoretically and experimentally the oxidation reaction kinetics of carbon aerogel using the non-parametric kinetic (NPK as a powerful method. For this purpose, a non-isothermal thermogravimetric analysis, at three different heating rates, was performed on three samples each with its specific pore structure, density and specific surface area. The most significant feature of this method, in comparison with the model-free isoconversional methods, is its ability to separate the functionality of the reaction rate with the degree of conversion and temperature by the direct use of thermogravimetric data. Using this method, it was observed that the Nomen-Sempere model could provide the best fit to the data, while the temperature dependence of the rate constant was best explained by a Vogel-Fulcher relationship, where the reference temperature was the onset temperature of oxidation. Moreover, it was found from the results of this work that the assumption of the Arrhenius relation for the temperature dependence of the rate constant led to over-estimation of the apparent activation energy (up to 160 kJ/mol that was considerably different from the values (up to 3.5 kJ/mol predicted by the Vogel-Fulcher relationship in isoconversional methods

  7. Assessment of water quality trends in the Minnesota River using non-parametric and parametric methods

    Science.gov (United States)

    Johnson, H.O.; Gupta, S.C.; Vecchia, A.V.; Zvomuya, F.

    2009-01-01

    Excessive loading of sediment and nutrients to rivers is a major problem in many parts of the United States. In this study, we tested the non-parametric Seasonal Kendall (SEAKEN) trend model and the parametric USGS Quality of Water trend program (QWTREND) to quantify trends in water quality of the Minnesota River at Fort Snelling from 1976 to 2003. Both methods indicated decreasing trends in flow-adjusted concentrations of total suspended solids (TSS), total phosphorus (TP), and orthophosphorus (OP) and a generally increasing trend in flow-adjusted nitrate plus nitrite-nitrogen (NO3-N) concentration. The SEAKEN results were strongly influenced by the length of the record as well as extreme years (dry or wet) earlier in the record. The QWTREND results, though influenced somewhat by the same factors, were more stable. The magnitudes of trends between the two methods were somewhat different and appeared to be associated with conceptual differences between the flow-adjustment processes used and with data processing methods. The decreasing trends in TSS, TP, and OP concentrations are likely related to conservation measures implemented in the basin. However, dilution effects from wet climate or additional tile drainage cannot be ruled out. The increasing trend in NO3-N concentrations was likely due to increased drainage in the basin. Since the Minnesota River is the main source of sediments to the Mississippi River, this study also addressed the rapid filling of Lake Pepin on the Mississippi River and found the likely cause to be increased flow due to recent wet climate in the region. Copyright ?? 2009 by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America. All rights reserved.

  8. Bayesian Semi- and Non-Parametric Models for Longitudinal Data with Multiple Membership Effects in R

    Directory of Open Access Journals (Sweden)

    Terrance Savitsky

    2014-03-01

    Full Text Available We introduce growcurves for R that performs analysis of repeated measures multiple membership (MM data. This data structure arises in studies under which an intervention is delivered to each subject through the subjects participation in a set of multiple elements that characterize the intervention. In our motivating study design under which subjects receive a group cognitive behavioral therapy (CBT treatment, an element is a group CBT session and each subject attends multiple sessions that, together, comprise the treatment. The sets of elements, or group CBT sessions, attended by subjects will partly overlap with some of those from other subjects to induce a dependence in their responses. The growcurves package offers two alternative sets of hierarchical models: 1. Separate terms are specified for multivariate subject and MM element random effects, where the subject effects are modeled under a Dirichlet process prior to produce a semi-parametric construction; 2. A single term is employed to model joint subject-by-MM effects. A fully non-parametric dependent Dirichlet process formulation allows exploration of differences in subject responses across different MM elements. This model allows for borrowing information among subjects who express similar longitudinal trajectories for flexible estimation. growcurves deploys estimation functions to perform posterior sampling under a suite of prior options. An accompanying set of plot functions allows the user to readily extract by-subject growth curves. The design approach intends to anticipate inferential goals with tools that fully extract information from repeated measures data. Computational efficiency is achieved by performing the sampling for estimation functions using compiled C++ code.

  9. Non-parametric kernel density estimation of species sensitivity distributions in developing water quality criteria of metals.

    Science.gov (United States)

    Wang, Ying; Wu, Fengchang; Giesy, John P; Feng, Chenglian; Liu, Yuedan; Qin, Ning; Zhao, Yujie

    2015-09-01

    Due to use of different parametric models for establishing species sensitivity distributions (SSDs), comparison of water quality criteria (WQC) for metals of the same group or period in the periodic table is uncertain and results can be biased. To address this inadequacy, a new probabilistic model, based on non-parametric kernel density estimation was developed and optimal bandwidths and testing methods are proposed. Zinc (Zn), cadmium (Cd), and mercury (Hg) of group IIB of the periodic table are widespread in aquatic environments, mostly at small concentrations, but can exert detrimental effects on aquatic life and human health. With these metals as target compounds, the non-parametric kernel density estimation method and several conventional parametric density estimation methods were used to derive acute WQC of metals for protection of aquatic species in China that were compared and contrasted with WQC for other jurisdictions. HC5 values for protection of different types of species were derived for three metals by use of non-parametric kernel density estimation. The newly developed probabilistic model was superior to conventional parametric density estimations for constructing SSDs and for deriving WQC for these metals. HC5 values for the three metals were inversely proportional to atomic number, which means that the heavier atoms were more potent toxicants. The proposed method provides a novel alternative approach for developing SSDs that could have wide application prospects in deriving WQC and use in assessment of risks to ecosystems.

  10. Parametric and non-parametric species delimitation methods result in the recognition of two new Neotropical woody bamboo species.

    Science.gov (United States)

    Ruiz-Sanchez, Eduardo

    2015-12-01

    The Neotropical woody bamboo genus Otatea is one of five genera in the subtribe Guaduinae. Of the eight described Otatea species, seven are endemic to Mexico and one is also distributed in Central and South America. Otatea acuminata has the widest geographical distribution of the eight species, and two of its recently collected populations do not match the known species morphologically. Parametric and non-parametric methods were used to delimit the species in Otatea using five chloroplast markers, one nuclear marker, and morphological characters. The parametric coalescent method and the non-parametric analysis supported the recognition of two distinct evolutionary lineages. Molecular clock estimates were used to estimate divergence times in Otatea. The results for divergence time in Otatea estimated the origin of the speciation events from the Late Miocene to Late Pleistocene. The species delimitation analyses (parametric and non-parametric) identified that the two populations of O. acuminata from Chiapas and Hidalgo are from two separate evolutionary lineages and these new species have morphological characters that separate them from O. acuminata s.s. The geological activity of the Trans-Mexican Volcanic Belt and the Isthmus of Tehuantepec may have isolated populations and limited the gene flow between Otatea species, driving speciation. Based on the results found here, I describe Otatea rzedowskiorum and Otatea victoriae as two new species, morphologically different from O. acuminata. Copyright © 2015 Elsevier Inc. All rights reserved.

  11. Single-case effect size calculation: comparing regression and non-parametric approaches across previously published reading intervention data sets.

    Science.gov (United States)

    Ross, Sarah G; Begeny, John C

    2014-08-01

    Growing from demands for accountability and research-based practice in the field of education, there is recent focus on developing standards for the implementation and analysis of single-case designs. Effect size methods for single-case designs provide a useful way to discuss treatment magnitude in the context of individual intervention. Although a standard effect size methodology does not yet exist within single-case research, panel experts recently recommended pairing regression and non-parametric approaches when analyzing effect size data. This study compared two single-case effect size methods: the regression-based, Allison-MT method and the newer, non-parametric, Tau-U method. Using previously published research that measured the Words read Correct per Minute (WCPM) variable, these two methods were examined by comparing differences in overall effect size scores and rankings of intervention effect. Results indicated that the regression method produced significantly larger effect sizes than the non-parametric method, but the rankings of the effect size scores had a strong, positive relation. Implications of these findings for research and practice are discussed. Copyright © 2014 Society for the Study of School Psychology. Published by Elsevier Ltd. All rights reserved.

  12. Parametric modeling of DSC-MRI data with stochastic filtration and optimal input design versus non-parametric modeling.

    Science.gov (United States)

    Kalicka, Renata; Pietrenko-Dabrowska, Anna

    2007-03-01

    In the paper MRI measurements are used for assessment of brain tissue perfusion and other features and functions of the brain (cerebral blood flow - CBF, cerebral blood volume - CBV, mean transit time - MTT). Perfusion is an important indicator of tissue viability and functioning as in pathological tissue blood flow, vascular and tissue structure are altered with respect to normal tissue. MRI enables diagnosing diseases at an early stage of their course. The parametric and non-parametric approaches to the identification of MRI models are presented and compared. The non-parametric modeling adopts gamma variate functions. The parametric three-compartmental catenary model, based on the general kinetic model, is also proposed. The parameters of the models are estimated on the basis of experimental data. The goodness of fit of the gamma variate and the three-compartmental models to the data and the accuracy of the parameter estimates are compared. Kalman filtering, smoothing the measurements, was adopted to improve the estimate accuracy of the parametric model. Parametric modeling gives a better fit and better parameter estimates than non-parametric and allows an insight into the functioning of the system. To improve the accuracy optimal experiment design related to the input signal was performed.

  13. A non-parametric Data Envelopment Analysis approach for improving energy efficiency of grape production

    International Nuclear Information System (INIS)

    Khoshroo, Alireza; Mulwa, Richard; Emrouznejad, Ali; Arabi, Behrouz

    2013-01-01

    Grape is one of the world's largest fruit crops with approximately 67.5 million tonnes produced each year and energy is an important element in modern grape productions as it heavily depends on fossil and other energy resources. Efficient use of these energies is a necessary step toward reducing environmental hazards, preventing destruction of natural resources and ensuring agricultural sustainability. Hence, identifying excessive use of energy as well as reducing energy resources is the main focus of this paper to optimize energy consumption in grape production. In this study we use a two-stage methodology to find the association of energy efficiency and performance explained by farmers' specific characteristics. In the first stage a non-parametric Data Envelopment Analysis is used to model efficiencies as an explicit function of human labor, machinery, chemicals, FYM (farmyard manure), diesel fuel, electricity and water for irrigation energies. In the second step, farm specific variables such as farmers' age, gender, level of education and agricultural experience are used in a Tobit regression framework to explain how these factors influence efficiency of grape farming. The result of the first stage shows substantial inefficiency between the grape producers in the studied area while the second stage shows that the main difference between efficient and inefficient farmers was in the use of chemicals, diesel fuel and water for irrigation. The use of chemicals such as insecticides, herbicides and fungicides were considerably less than inefficient ones. The results revealed that the more educated farmers are more energy efficient in comparison with their less educated counterparts. - Highlights: • The focus of this paper is to identify excessive use of energy and optimize energy consumption in grape production. • We measure the efficiency as a function of labor/machinery/chemicals/farmyard manure/diesel-fuel/electricity/water. • Data were obtained from 41 grape

  14. Monitoring coastal marshes biomass with CASI: a comparison of parametric and non-parametric models

    Science.gov (United States)

    Mo, Y.; Kearney, M.

    2017-12-01

    Coastal marshes are important carbon sinks that face multiple natural and anthropogenic stresses. Optical remote sensing is a powerful tool for closely monitoring the biomass of coastal marshes. However, application of hyperspectral sensors on assessing the biomass of diverse coastal marsh ecosystems is limited. This study samples spectral and biophysical data from coastal freshwater, intermediate, brackish, and saline marshes in Louisiana, and develops parametric and non-parametric models for using the Compact Airborne Spectrographic Imager (CASI) to retrieve the marshes' biomass. Linear models and random forest models are developed from simulated CASI data (48 bands, 380-1050 nm, bandwidth 14 nm). Linear models are also developed using narrowband vegetation indices computed from all possible band combinations from the blue, red, and near infrared wavelengths. It is found that the linear models derived from the optimal narrowband vegetation indices provide strong predictions for the marshes' Leaf Area Index (LAI; R2 > 0.74 for ARVI), but not for their Aboveground Green Biomass (AGB; R2 > 0.25). The linear models derived from the simulated CASI data strongly predict the marshes' LAI (R2 = 0.93) and AGB (R2 = 0.71) and have 27 and 30 bands/variables in the final models through stepwise regression, respectively. The random forest models derived from the simulated CASI data also strongly predict the marshes' LAI and AGB (R2 = 0.91 and 0.84, respectively), where the most important variables for predicting LAI are near infrared bands at 784 and 756 nm and for predicting ABG are red bands at 684 and 670 nm. In sum, the random forest model is preferable for assessing coastal marsh biomass using CASI data as it offers high R2 for both LAI and AGB. The superior performance of the random forest model is likely to due to that it fully utilizes the full-spectrum data and makes no assumption of the approximate normality of the sampling population. This study offers solutions

  15. Evaluation of world's largest social welfare scheme: An assessment using non-parametric approach.

    Science.gov (United States)

    Singh, Sanjeet

    2016-08-01

    Mahatma Gandhi National Rural Employment Guarantee Act (MGNREGA) is the world's largest social welfare scheme in India for the poverty alleviation through rural employment generation. This paper aims to evaluate and rank the performance of the states in India under MGNREGA scheme. A non-parametric approach, Data Envelopment Analysis (DEA) is used to calculate the overall technical, pure technical, and scale efficiencies of states in India. The sample data is drawn from the annual official reports published by the Ministry of Rural Development, Government of India. Based on three selected input parameters (expenditure indicators) and five output parameters (employment generation indicators), I apply both input and output oriented DEA models to estimate how well the states utilize their resources and generate outputs during the financial year 2013-14. The relative performance evaluation has been made under the assumption of constant returns and also under variable returns to scale to assess the impact of scale on performance. The results indicate that the main source of inefficiency is both technical and managerial practices adopted. 11 states are overall technically efficient and operate at the optimum scale whereas 18 states are pure technical or managerially efficient. It has been found that for some states it necessary to alter scheme size to perform at par with the best performing states. For inefficient states optimal input and output targets along with the resource savings and output gains are calculated. Analysis shows that if all inefficient states operate at optimal input and output levels, on an average 17.89% of total expenditure and a total amount of $780million could have been saved in a single year. Most of the inefficient states perform poorly when it comes to the participation of women and disadvantaged sections (SC&ST) in the scheme. In order to catch up with the performance of best performing states, inefficient states on an average need to enhance

  16. Estimation of Sparkover Rate of Medium-Voltage Line due to Direct Lightning Hit Taking Account of Statistics on Observed Return-Stroke Current

    Science.gov (United States)

    Hongo, Yasuji; Michishita, Koji

    The overvoltage associated with direct lightning hits has been the important factor for the insulation design of a distribution line. In this paper, the sparkover rate of a medium-voltage line associated with direct lightning hits is investigated based on numerical calculations obtained by using EMTP and statistical analysis by taking account of the correlation between the peak value and the front duration of return-stroke current waveform. When the line is equipped with surge arresters at the interval of 100m in addition to the overhead ground wire, the sparkover rate associated with subsequent strokes is higher than that associated with first strokes. This demonstrates the importance of the study of current parameters for subsequent strokes.

  17. Sparsity-promoting and edge-preserving maximum a posteriori estimators in non-parametric Bayesian inverse problems

    Science.gov (United States)

    Agapiou, Sergios; Burger, Martin; Dashti, Masoumeh; Helin, Tapio

    2018-04-01

    We consider the inverse problem of recovering an unknown functional parameter u in a separable Banach space, from a noisy observation vector y of its image through a known possibly non-linear map {{\\mathcal G}} . We adopt a Bayesian approach to the problem and consider Besov space priors (see Lassas et al (2009 Inverse Problems Imaging 3 87-122)), which are well-known for their edge-preserving and sparsity-promoting properties and have recently attracted wide attention especially in the medical imaging community. Our key result is to show that in this non-parametric setup the maximum a posteriori (MAP) estimates are characterized by the minimizers of a generalized Onsager-Machlup functional of the posterior. This is done independently for the so-called weak and strong MAP estimates, which as we show coincide in our context. In addition, we prove a form of weak consistency for the MAP estimators in the infinitely informative data limit. Our results are remarkable for two reasons: first, the prior distribution is non-Gaussian and does not meet the smoothness conditions required in previous research on non-parametric MAP estimates. Second, the result analytically justifies existing uses of the MAP estimate in finite but high dimensional discretizations of Bayesian inverse problems with the considered Besov priors.

  18. Comparison of non-parametric methods for ungrouping coarsely aggregated data

    DEFF Research Database (Denmark)

    Rizzi, Silvia; Thinggaard, Mikael; Engholm, Gerda

    2016-01-01

    composite link model performs the best. Conclusion We give an overview and test different methods to estimate detailed distributions from grouped count data. Health researchers can benefit from these versatile methods, which are ready for use in the statistical software R. We recommend using the penalized...

  19. Comparing non-parametric methods for ungrouping coarsely aggregated age-specific distributions

    DEFF Research Database (Denmark)

    Rizzi, Silvia; Thinggaard, Mikael; Vaupel, James W.

    2016-01-01

    Demographers have often access to vital statistics that are less than ideal for the purpose of their research. In many instances demographic data are reported in coarse histograms, where the values given are only the summation of true latent values, thereby making detailed analysis troublesome. O...

  20. Non-Parametric Inference for Ordered Alternatives in a Randomized Block Design

    Science.gov (United States)

    Hettmansperger, Thomas P.

    1975-01-01

    Treats the problem of testing an ordered hypothesis based on the ranks of the data. Statistical procedures for the randomized block design with more than one observation per cell are derived. Multiple comparisions and estimation procedures are included. (Author/RC)

  1. Non-parametric probabilistic forecasts of wind power: required properties and evaluation

    DEFF Research Database (Denmark)

    Pinson, Pierre; Nielsen, Henrik Aalborg; Møller, Jan Kloppenborg

    2007-01-01

    of a single or a set of quantile forecasts. The required and desirable properties of such probabilistic forecasts are defined and a framework for their evaluation is proposed. This framework is applied for evaluating the quality of two statistical methods producing full predictive distributions from point...

  2. A non-parametric conditional bivariate reference region with an application to height/weight measurements on normal girls

    DEFF Research Database (Denmark)

    Petersen, Jørgen Holm

    2009-01-01

    A conceptually simple two-dimensional conditional reference curve is described. The curve gives a decision basis for determining whether a bivariate response from an individual is "normal" or "abnormal" when taking into account that a third (conditioning) variable may influence the bivariate...... response. The reference curve is not only characterized analytically but also by geometric properties that are easily communicated to medical doctors - the users of such curves. The reference curve estimator is completely non-parametric, so no distributional assumptions are needed about the two......-dimensional response. An example that will serve to motivate and illustrate the reference is the study of the height/weight distribution of 7-8-year-old Danish school girls born in 1930, 1950, or 1970....

  3. Statistics

    CERN Document Server

    Hayslett, H T

    1991-01-01

    Statistics covers the basic principles of Statistics. The book starts by tackling the importance and the two kinds of statistics; the presentation of sample data; the definition, illustration and explanation of several measures of location; and the measures of variation. The text then discusses elementary probability, the normal distribution and the normal approximation to the binomial. Testing of statistical hypotheses and tests of hypotheses about the theoretical proportion of successes in a binomial population and about the theoretical mean of a normal population are explained. The text the

  4. Non-parametric Bayesian models of response function in dynamic image sequences

    Czech Academy of Sciences Publication Activity Database

    Tichý, Ondřej; Šmídl, Václav

    2016-01-01

    Roč. 151, č. 1 (2016), s. 90-100 ISSN 1077-3142 R&D Projects: GA ČR GA13-29225S Institutional support: RVO:67985556 Keywords : Response function * Blind source separation * Dynamic medical imaging * Probabilistic models * Bayesian methods Subject RIV: BB - Applied Statistics, Operational Research Impact factor: 2.498, year: 2016 http://library.utia.cas.cz/separaty/2016/AS/tichy-0456983.pdf

  5. A new non-parametric stationarity test of time series in the time domain

    KAUST Repository

    Jin, Lei

    2014-11-07

    © 2015 The Royal Statistical Society and Blackwell Publishing Ltd. We propose a new double-order selection test for checking second-order stationarity of a time series. To develop the test, a sequence of systematic samples is defined via Walsh functions. Then the deviations of the autocovariances based on these systematic samples from the corresponding autocovariances of the whole time series are calculated and the uniform asymptotic joint normality of these deviations over different systematic samples is obtained. With a double-order selection scheme, our test statistic is constructed by combining the deviations at different lags in the systematic samples. The null asymptotic distribution of the statistic proposed is derived and the consistency of the test is shown under fixed and local alternatives. Simulation studies demonstrate well-behaved finite sample properties of the method proposed. Comparisons with some existing tests in terms of power are given both analytically and empirically. In addition, the method proposed is applied to check the stationarity assumption of a chemical process viscosity readings data set.

  6. Statistics

    Science.gov (United States)

    Links to sources of cancer-related statistics, including the Surveillance, Epidemiology and End Results (SEER) Program, SEER-Medicare datasets, cancer survivor prevalence data, and the Cancer Trends Progress Report.

  7. A new measure for gene expression biclustering based on non-parametric correlation.

    Science.gov (United States)

    Flores, Jose L; Inza, Iñaki; Larrañaga, Pedro; Calvo, Borja

    2013-12-01

    One of the emerging techniques for performing the analysis of the DNA microarray data known as biclustering is the search of subsets of genes and conditions which are coherently expressed. These subgroups provide clues about the main biological processes. Until now, different approaches to this problem have been proposed. Most of them use the mean squared residue as quality measure but relevant and interesting patterns can not be detected such as shifting, or scaling patterns. Furthermore, recent papers show that there exist new coherence patterns involved in different kinds of cancer and tumors such as inverse relationships between genes which can not be captured. The proposed measure is called Spearman's biclustering measure (SBM) which performs an estimation of the quality of a bicluster based on the non-linear correlation among genes and conditions simultaneously. The search of biclusters is performed by using a evolutionary technique called estimation of distribution algorithms which uses the SBM measure as fitness function. This approach has been examined from different points of view by using artificial and real microarrays. The assessment process has involved the use of quality indexes, a set of bicluster patterns of reference including new patterns and a set of statistical tests. It has been also examined the performance using real microarrays and comparing to different algorithmic approaches such as Bimax, CC, OPSM, Plaid and xMotifs. SBM shows several advantages such as the ability to recognize more complex coherence patterns such as shifting, scaling and inversion and the capability to selectively marginalize genes and conditions depending on the statistical significance. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

  8. Non-parametric characterization of long-term rainfall time series

    Science.gov (United States)

    Tiwari, Harinarayan; Pandey, Brij Kishor

    2018-03-01

    The statistical study of rainfall time series is one of the approaches for efficient hydrological system design. Identifying, and characterizing long-term rainfall time series could aid in improving hydrological systems forecasting. In the present study, eventual statistics was applied for the long-term (1851-2006) rainfall time series under seven meteorological regions of India. Linear trend analysis was carried out using Mann-Kendall test for the observed rainfall series. The observed trend using the above-mentioned approach has been ascertained using the innovative trend analysis method. Innovative trend analysis has been found to be a strong tool to detect the general trend of rainfall time series. Sequential Mann-Kendall test has also been carried out to examine nonlinear trends of the series. The partial sum of cumulative deviation test is also found to be suitable to detect the nonlinear trend. Innovative trend analysis, sequential Mann-Kendall test and partial cumulative deviation test have potential to detect the general as well as nonlinear trend for the rainfall time series. Annual rainfall analysis suggests that the maximum changes in mean rainfall is 11.53% for West Peninsular India, whereas the maximum fall in mean rainfall is 7.8% for the North Mountainous Indian region. The innovative trend analysis method is also capable of finding the number of change point available in the time series. Additionally, we have performed von Neumann ratio test and cumulative deviation test to estimate the departure from homogeneity. Singular spectrum analysis has been applied in this study to evaluate the order of departure from homogeneity in the rainfall time series. Monsoon season (JS) of North Mountainous India and West Peninsular India zones has higher departure from homogeneity and singular spectrum analysis shows the results to be in coherence with the same.

  9. Non-parametric causality detection: An application to social media and financial data

    Science.gov (United States)

    Tsapeli, Fani; Musolesi, Mirco; Tino, Peter

    2017-10-01

    According to behavioral finance, stock market returns are influenced by emotional, social and psychological factors. Several recent works support this theory by providing evidence of correlation between stock market prices and collective sentiment indexes measured using social media data. However, a pure correlation analysis is not sufficient to prove that stock market returns are influenced by such emotional factors since both stock market prices and collective sentiment may be driven by a third unmeasured factor. Controlling for factors that could influence the study by applying multivariate regression models is challenging given the complexity of stock market data. False assumptions about the linearity or non-linearity of the model and inaccuracies on model specification may result in misleading conclusions. In this work, we propose a novel framework for causal inference that does not require any assumption about a particular parametric form of the model expressing statistical relationships among the variables of the study and can effectively control a large number of observed factors. We apply our method in order to estimate the causal impact that information posted in social media may have on stock market returns of four big companies. Our results indicate that social media data not only correlate with stock market returns but also influence them.

  10. Statistics

    International Nuclear Information System (INIS)

    2005-01-01

    For the years 2004 and 2005 the figures shown in the tables of Energy Review are partly preliminary. The annual statistics published in Energy Review are presented in more detail in a publication called Energy Statistics that comes out yearly. Energy Statistics also includes historical time-series over a longer period of time (see e.g. Energy Statistics, Statistics Finland, Helsinki 2004.) The applied energy units and conversion coefficients are shown in the back cover of the Review. Explanatory notes to the statistical tables can be found after tables and figures. The figures presents: Changes in GDP, energy consumption and electricity consumption, Carbon dioxide emissions from fossile fuels use, Coal consumption, Consumption of natural gas, Peat consumption, Domestic oil deliveries, Import prices of oil, Consumer prices of principal oil products, Fuel prices in heat production, Fuel prices in electricity production, Price of electricity by type of consumer, Average monthly spot prices at the Nord pool power exchange, Total energy consumption by source and CO 2 -emissions, Supplies and total consumption of electricity GWh, Energy imports by country of origin in January-June 2003, Energy exports by recipient country in January-June 2003, Consumer prices of liquid fuels, Consumer prices of hard coal, natural gas and indigenous fuels, Price of natural gas by type of consumer, Price of electricity by type of consumer, Price of district heating by type of consumer, Excise taxes, value added taxes and fiscal charges and fees included in consumer prices of some energy sources and Energy taxes, precautionary stock fees and oil pollution fees

  11. Opening the Black Box of Intra-Household Decision-Making : Theory and Non-Parametric Empirical Tests of General Collective Consumption Models

    NARCIS (Netherlands)

    Cherchye, L.J.H.; de Rock, B.; Vermeulen, F.M.P.

    2005-01-01

    We non-parametrically test a general collective consumption model with public consumption and externalities inside the household.We further propose a novel approach to model special cases of the general collective model.These special cases include alternative restrictions on the 'sharing rule' that

  12. Comparing parametric and non-parametric classifiers for remote sensing of tree species across a land use gradient in a Savanna landscape

    CSIR Research Space (South Africa)

    Cho, Moses A

    2012-11-01

    Full Text Available International Conference of the African Association of Remote Sensing and the Environment, El Jadida Morocco, October 29 to November 2, 2012 COMPARING PARAMETRIC AND NON-PARAMETRIC CLASSIFIERS FOR REMOTE SENSING OF TREE SPECIES ACROSS A LAND USE GRADIENT...

  13. Statistics

    International Nuclear Information System (INIS)

    2000-01-01

    For the year 1999 and 2000, part of the figures shown in the tables of the Energy Review are preliminary or estimated. The annual statistics of the Energy Review appear in more detail from the publication Energiatilastot - Energy Statistics issued annually, which also includes historical time series over a longer period (see e.g., Energiatilastot 1998, Statistics Finland, Helsinki 1999, ISSN 0785-3165). The inside of the Review's back cover shows the energy units and the conversion coefficients used for them. Explanatory notes to the statistical tables can be found after tables and figures. The figures presents: Changes in the volume of GNP and energy consumption, Changes in the volume of GNP and electricity, Coal consumption, Natural gas consumption, Peat consumption, Domestic oil deliveries, Import prices of oil, Consumer prices of principal oil products, Fuel prices for heat production, Fuel prices for electricity production, Carbon dioxide emissions, Total energy consumption by source and CO 2 -emissions, Electricity supply, Energy imports by country of origin in January-March 2000, Energy exports by recipient country in January-March 2000, Consumer prices of liquid fuels, Consumer prices of hard coal, natural gas and indigenous fuels, Average electricity price by type of consumer, Price of district heating by type of consumer, Excise taxes, value added taxes and fiscal charges and fees included in consumer prices of some energy sources and Energy taxes and precautionary stock fees on oil products

  14. Statistics

    International Nuclear Information System (INIS)

    1999-01-01

    For the year 1998 and the year 1999, part of the figures shown in the tables of the Energy Review are preliminary or estimated. The annual statistics of the Energy Review appear in more detail from the publication Energiatilastot - Energy Statistics issued annually, which also includes historical time series over a longer period (see e.g. Energiatilastot 1998, Statistics Finland, Helsinki 1999, ISSN 0785-3165). The inside of the Review's back cover shows the energy units and the conversion coefficients used for them. Explanatory notes to the statistical tables can be found after tables and figures. The figures presents: Changes in the volume of GNP and energy consumption, Changes in the volume of GNP and electricity, Coal consumption, Natural gas consumption, Peat consumption, Domestic oil deliveries, Import prices of oil, Consumer prices of principal oil products, Fuel prices for heat production, Fuel prices for electricity production, Carbon dioxide emissions, Total energy consumption by source and CO 2 -emissions, Electricity supply, Energy imports by country of origin in January-June 1999, Energy exports by recipient country in January-June 1999, Consumer prices of liquid fuels, Consumer prices of hard coal, natural gas and indigenous fuels, Average electricity price by type of consumer, Price of district heating by type of consumer, Excise taxes, value added taxes and fiscal charges and fees included in consumer prices of some energy sources and Energy taxes and precautionary stock fees on oil products

  15. Statistics

    International Nuclear Information System (INIS)

    2001-01-01

    For the year 2000, part of the figures shown in the tables of the Energy Review are preliminary or estimated. The annual statistics of the Energy Review appear in more detail from the publication Energiatilastot - Energy Statistics issued annually, which also includes historical time series over a longer period (see e.g. Energiatilastot 1999, Statistics Finland, Helsinki 2000, ISSN 0785-3165). The inside of the Review's back cover shows the energy units and the conversion coefficients used for them. Explanatory notes to the statistical tables can be found after tables and figures. The figures presents: Changes in the volume of GNP and energy consumption, Changes in the volume of GNP and electricity, Coal consumption, Natural gas consumption, Peat consumption, Domestic oil deliveries, Import prices of oil, Consumer prices of principal oil products, Fuel prices for heat production, Fuel prices for electricity production, Carbon dioxide emissions from the use of fossil fuels, Total energy consumption by source and CO 2 -emissions, Electricity supply, Energy imports by country of origin in 2000, Energy exports by recipient country in 2000, Consumer prices of liquid fuels, Consumer prices of hard coal, natural gas and indigenous fuels, Average electricity price by type of consumer, Price of district heating by type of consumer, Excise taxes, value added taxes and fiscal charges and fees included in consumer prices of some energy sources and Energy taxes and precautionary stock fees on oil products

  16. Non-parametric temporal modeling of the hemodynamic response function via a liquid state machine.

    Science.gov (United States)

    Avesani, Paolo; Hazan, Hananel; Koilis, Ester; Manevitz, Larry M; Sona, Diego

    2015-10-01

    Standard methods for the analysis of functional MRI data strongly rely on prior implicit and explicit hypotheses made to simplify the analysis. In this work the attention is focused on two such commonly accepted hypotheses: (i) the hemodynamic response function (HRF) to be searched in the BOLD signal can be described by a specific parametric model e.g., double-gamma; (ii) the effect of stimuli on the signal is taken to be linearly additive. While these assumptions have been empirically proven to generate high sensitivity for statistical methods, they also limit the identification of relevant voxels to what is already postulated in the signal, thus not allowing the discovery of unknown correlates in the data due to the presence of unexpected hemodynamics. This paper tries to overcome these limitations by proposing a method wherein the HRF is learned directly from data rather than induced from its basic form assumed in advance. This approach produces a set of voxel-wise models of HRF and, as a result, relevant voxels are filterable according to the accuracy of their prediction in a machine learning framework. This approach is instantiated using a temporal architecture based on the paradigm of Reservoir Computing wherein a Liquid State Machine is combined with a decoding Feed-Forward Neural Network. This splits the modeling into two parts: first a representation of the complex temporal reactivity of the hemodynamic response is determined by a universal global "reservoir" which is essentially temporal; second an interpretation of the encoded representation is determined by a standard feed-forward neural network, which is trained by the data. Thus the reservoir models the temporal state of information during and following temporal stimuli in a feed-back system, while the neural network "translates" this data to fit the specific HRF response as given, e.g. by BOLD signal measurements in fMRI. An empirical analysis on synthetic datasets shows that the learning process can

  17. A multi-instrument non-parametric reconstruction of the electron pressure profile in the galaxy cluster CLJ1226.9+3332

    Science.gov (United States)

    Romero, C.; McWilliam, M.; Macías-Pérez, J.-F.; Adam, R.; Ade, P.; André, P.; Aussel, H.; Beelen, A.; Benoît, A.; Bideaud, A.; Billot, N.; Bourrion, O.; Calvo, M.; Catalano, A.; Coiffard, G.; Comis, B.; de Petris, M.; Désert, F.-X.; Doyle, S.; Goupy, J.; Kramer, C.; Lagache, G.; Leclercq, S.; Lestrade, J.-F.; Mauskopf, P.; Mayet, F.; Monfardini, A.; Pascale, E.; Perotto, L.; Pisano, G.; Ponthieu, N.; Revéret, V.; Ritacco, A.; Roussel, H.; Ruppin, F.; Schuster, K.; Sievers, A.; Triqueneaux, S.; Tucker, C.; Zylka, R.

    2018-04-01

    Context. In the past decade, sensitive, resolved Sunyaev-Zel'dovich (SZ) studies of galaxy clusters have become common. Whereas many previous SZ studies have parameterized the pressure profiles of galaxy clusters, non-parametric reconstructions will provide insights into the thermodynamic state of the intracluster medium. Aim. We seek to recover the non-parametric pressure profiles of the high redshift (z = 0.89) galaxy cluster CLJ 1226.9+3332 as inferred from SZ data from the MUSTANG, NIKA, Bolocam, and Planck instruments, which all probe different angular scales. Methods: Our non-parametric algorithm makes use of logarithmic interpolation, which under the assumption of ellipsoidal symmetry is analytically integrable. For MUSTANG, NIKA, and Bolocam we derive a non-parametric pressure profile independently and find good agreement among the instruments. In particular, we find that the non-parametric profiles are consistent with a fitted generalized Navaro-Frenk-White (gNFW) profile. Given the ability of Planck to constrain the total signal, we include a prior on the integrated Compton Y parameter as determined by Planck. Results: For a given instrument, constraints on the pressure profile diminish rapidly beyond the field of view. The overlap in spatial scales probed by these four datasets is therefore critical in checking for consistency between instruments. By using multiple instruments, our analysis of CLJ 1226.9+3332 covers a large radial range, from the central regions to the cluster outskirts: 0.05 R500 generation of SZ instruments such as NIKA2 and MUSTANG2.

  18. Statistics

    International Nuclear Information System (INIS)

    2003-01-01

    For the year 2002, part of the figures shown in the tables of the Energy Review are partly preliminary. The annual statistics of the Energy Review also includes historical time-series over a longer period (see e.g. Energiatilastot 2001, Statistics Finland, Helsinki 2002). The applied energy units and conversion coefficients are shown in the inside back cover of the Review. Explanatory notes to the statistical tables can be found after tables and figures. The figures presents: Changes in GDP, energy consumption and electricity consumption, Carbon dioxide emissions from fossile fuels use, Coal consumption, Consumption of natural gas, Peat consumption, Domestic oil deliveries, Import prices of oil, Consumer prices of principal oil products, Fuel prices in heat production, Fuel prices in electricity production, Price of electricity by type of consumer, Average monthly spot prices at the Nord pool power exchange, Total energy consumption by source and CO 2 -emissions, Supply and total consumption of electricity GWh, Energy imports by country of origin in January-June 2003, Energy exports by recipient country in January-June 2003, Consumer prices of liquid fuels, Consumer prices of hard coal, natural gas and indigenous fuels, Price of natural gas by type of consumer, Price of electricity by type of consumer, Price of district heating by type of consumer, Excise taxes, value added taxes and fiscal charges and fees included in consumer prices of some energy sources and Excise taxes, precautionary stock fees on oil pollution fees on energy products

  19. Statistics

    International Nuclear Information System (INIS)

    2000-01-01

    For the year 1999 and 2000, part of the figures shown in the tables of the Energy Review are preliminary or estimated. The annual statistics of the Energy also includes historical time series over a longer period (see e.g., Energiatilastot 1999, Statistics Finland, Helsinki 2000, ISSN 0785-3165). The inside of the Review's back cover shows the energy units and the conversion coefficients used for them. Explanatory notes to the statistical tables can be found after tables and figures. The figures presents: Changes in the volume of GNP and energy consumption, Changes in the volume of GNP and electricity, Coal consumption, Natural gas consumption, Peat consumption, Domestic oil deliveries, Import prices of oil, Consumer prices of principal oil products, Fuel prices for heat production, Fuel prices for electricity production, Carbon dioxide emissions, Total energy consumption by source and CO 2 -emissions, Electricity supply, Energy imports by country of origin in January-June 2000, Energy exports by recipient country in January-June 2000, Consumer prices of liquid fuels, Consumer prices of hard coal, natural gas and indigenous fuels, Average electricity price by type of consumer, Price of district heating by type of consumer, Excise taxes, value added taxes and fiscal charges and fees included in consumer prices of some energy sources and Energy taxes and precautionary stock fees on oil products

  20. Statistics

    International Nuclear Information System (INIS)

    2004-01-01

    For the year 2003 and 2004, the figures shown in the tables of the Energy Review are partly preliminary. The annual statistics of the Energy Review also includes historical time-series over a longer period (see e.g. Energiatilastot, Statistics Finland, Helsinki 2003, ISSN 0785-3165). The applied energy units and conversion coefficients are shown in the inside back cover of the Review. Explanatory notes to the statistical tables can be found after tables and figures. The figures presents: Changes in GDP, energy consumption and electricity consumption, Carbon dioxide emissions from fossile fuels use, Coal consumption, Consumption of natural gas, Peat consumption, Domestic oil deliveries, Import prices of oil, Consumer prices of principal oil products, Fuel prices in heat production, Fuel prices in electricity production, Price of electricity by type of consumer, Average monthly spot prices at the Nord pool power exchange, Total energy consumption by source and CO 2 -emissions, Supplies and total consumption of electricity GWh, Energy imports by country of origin in January-March 2004, Energy exports by recipient country in January-March 2004, Consumer prices of liquid fuels, Consumer prices of hard coal, natural gas and indigenous fuels, Price of natural gas by type of consumer, Price of electricity by type of consumer, Price of district heating by type of consumer, Excise taxes, value added taxes and fiscal charges and fees included in consumer prices of some energy sources and Excise taxes, precautionary stock fees on oil pollution fees

  1. Statistical methods for analysing Barthel scores in trials of poststroke interventions: a review and computer simulations.

    Science.gov (United States)

    Song, Fujian; Jerosch-Herold, Christina; Holland, Richard; Drachler, Maria de Lourdes; Mares, Kath; Harvey, Ian

    2006-04-01

    Arguments persist as to whether parametric or non-parametric methods should be used to analyse ordinal data in trials. This paper aims to assess methods used for presenting and analysing an ordinal scale, the Barthel Index, in trials of poststroke interventions. All randomized controlled trials (RCTs) of poststroke interventions published from 1995 to 2004 in two journals (Stroke and Clinical Rehabilitation) were scrutinized for methods used to present and analyse Barthel scores. Computer simulations were used to compare the type I errors and the statistical power of different statistical methods under a range of assumed circumstances. One hundred and fifty-six RCTs were identified within the two journals. The central tendency of Barthel scores was measured by the median in 47 trials and by the mean in 35 trials. Non-parametric analyses of Barthel scores were conducted in 47 trials and parametric methods used in 18 trials. The results of computer simulations demonstrate that the t-test has a similar type I error rate and statistical power when compared with the rank sum test. However, when a zero final Barthel score is assigned to patients who have died, the statistical power of the t-test is much reduced. The possible maximal statistical power of dichotomization and ordinal regression is usually much lower than that of the rank sum test. To facilitate comparison and meta-analysis, we recommend that mean values (with standard deviations or standard errors) of Barthel scores should be routinely reported in trials of poststroke interventions. The rank sum test appears the most powerful inferential technique for detecting differences in Barthel scores.

  2. Non-parametric reconstruction of an inflaton potential from Einstein–Cartan–Sciama–Kibble gravity with particle production

    Directory of Open Access Journals (Sweden)

    Shantanu Desai

    2016-04-01

    Full Text Available The coupling between spin and torsion in the Einstein–Cartan–Sciama–Kibble theory of gravity generates gravitational repulsion at very high densities, which prevents a singularity in a black hole and may create there a new universe. We show that quantum particle production in such a universe near the last bounce, which represents the Big Bang, gives the dynamics that solves the horizon, flatness, and homogeneity problems in cosmology. For a particular range of the particle production coefficient, we obtain a nearly constant Hubble parameter that gives an exponential expansion of the universe with more than 60 e-folds, which lasts about ∼10−42 s. This scenario can thus explain cosmic inflation without requiring a fundamental scalar field and reheating. From the obtained time dependence of the scale factor, we follow the prescription of Ellis and Madsen to reconstruct in a non-parametric way a scalar field potential which gives the same dynamics of the early universe. This potential gives the slow-roll parameters of cosmic inflation, from which we calculate the tensor-to-scalar ratio, the scalar spectral index of density perturbations, and its running as functions of the production coefficient. We find that these quantities do not significantly depend on the scale factor at the Big Bounce. Our predictions for these quantities are consistent with the Planck 2015 observations.

  3. Non-parametric analysis of infrared spectra for recognition of glass and glass ceramic fragments in recycling plants.

    Science.gov (United States)

    Farcomeni, Alessio; Serranti, Silvia; Bonifazi, Giuseppe

    2008-01-01

    Glass ceramic detection in glass recycling plants represents a still unsolved problem, as glass ceramic material looks like normal glass and is usually detected only by specialized personnel. The presence of glass-like contaminants inside waste glass products, resulting from both industrial and differentiated urban waste collection, increases process production costs and reduces final product quality. In this paper an innovative approach for glass ceramic recognition, based on the non-parametric analysis of infrared spectra, is proposed and investigated. The work was specifically addressed to the spectral classification of glass and glass ceramic fragments collected in an actual recycling plant from three different production lines: flat glass, colored container-glass and white container-glass. The analyses, carried out in the near and mid-infrared (NIR-MIR) spectral field (1280-4480 nm), show that glass ceramic and glass fragments can be recognized by applying a wavelet transform, with a small classification error. Moreover, a method for selecting only a small subset of relevant wavelength ratios is suggested, allowing the conduct of a fast recognition of the two classes of materials. The results show how the proposed approach can be utilized to develop a classification engine to be integrated inside a hardware and software sorting architecture for fast "on-line" ceramic glass recognition and separation.

  4. The Importance of Integrating Clinical Relevance and Statistical Significance in the Assessment of Quality of Care--Illustrated Using the Swedish Stroke Register.

    Directory of Open Access Journals (Sweden)

    Anita Lindmark

    Full Text Available When profiling hospital performance, quality inicators are commonly evaluated through hospital-specific adjusted means with confidence intervals. When identifying deviations from a norm, large hospitals can have statistically significant results even for clinically irrelevant deviations while important deviations in small hospitals can remain undiscovered. We have used data from the Swedish Stroke Register (Riksstroke to illustrate the properties of a benchmarking method that integrates considerations of both clinical relevance and level of statistical significance.The performance measure used was case-mix adjusted risk of death or dependency in activities of daily living within 3 months after stroke. A hospital was labeled as having outlying performance if its case-mix adjusted risk exceeded a benchmark value with a specified statistical confidence level. The benchmark was expressed relative to the population risk and should reflect the clinically relevant deviation that is to be detected. A simulation study based on Riksstroke patient data from 2008-2009 was performed to investigate the effect of the choice of the statistical confidence level and benchmark value on the diagnostic properties of the method.Simulations were based on 18,309 patients in 76 hospitals. The widely used setting, comparing 95% confidence intervals to the national average, resulted in low sensitivity (0.252 and high specificity (0.991. There were large variations in sensitivity and specificity for different requirements of statistical confidence. Lowering statistical confidence improved sensitivity with a relatively smaller loss of specificity. Variations due to different benchmark values were smaller, especially for sensitivity. This allows the choice of a clinically relevant benchmark to be driven by clinical factors without major concerns about sufficiently reliable evidence.The study emphasizes the importance of combining clinical relevance and level of statistical

  5. Energy-saving and emission-abatement potential of Chinese coal-fired power enterprise: A non-parametric analysis

    International Nuclear Information System (INIS)

    Wei, Chu; Löschel, Andreas; Liu, Bing

    2015-01-01

    In the context of soaring demand for electricity, mitigating and controlling greenhouse gas emissions is a great challenge for China's power sector. Increasing attention has been placed on the evaluation of energy efficiency and CO 2 abatement potential in the power sector. However, studies at the micro-level are relatively rare due to serious data limitations. This study uses the 2004 and 2008 Census data of Zhejiang province to construct a non-parametric frontier in order to assess the abatement space of energy and associated CO 2 emission from China's coal-fired power enterprises. A Weighted Russell Directional Distance Function (WRDDF) is applied to construct an energy-saving potential index and a CO 2 emission-abatement potential index. Both indicators depict the inefficiency level in terms of energy utilization and CO 2 emissions of electric power plants. Our results show a substantial variation of energy-saving potential and CO 2 abatement potential among enterprises. We find that large power enterprises are less efficient in 2004, but become more efficient than smaller enterprises in 2008. State-owned enterprises (SOE) are not significantly different in 2008 from 2004, but perform better than their non-SOE counterparts in 2008. This change in performance for large enterprises and SOE might be driven by the “top-1000 Enterprise Energy Conservation Action” that was implemented in 2006. - Highlights: • Energy-saving potential and CO 2 abatement-potential for Chinese power enterprise are evaluated. • The potential to curb energy and emission shows great variation and dynamic changes. • Large enterprise is less efficient than small enterprise in 2004, but more efficient in 2008. • The state-owned enterprise performs better than non-state-owned enterprise in 2008

  6. Short-term monitoring of benzene air concentration in an urban area: a preliminary study of application of Kruskal-Wallis non-parametric test to assess pollutant impact on global environment and indoor

    Directory of Open Access Journals (Sweden)

    Maria Chiara Mura

    2010-12-01

    Full Text Available In step with the need to develop statistical procedures to manage small-size environmental samples, in this work we have used concentration values of benzene (C6H6, concurrently detected by seven outdoor and indoor monitoring stations over 12 000 minutes, in order to assess the representativeness of collected data and the impact of the pollutant on indoor environment. Clearly, the former issue is strictly connected to sampling-site geometry, which proves critical to correctly retrieving information from analysis of pollutants of sanitary interest. Therefore, according to current criteria for network-planning, single stations have been interpreted as nodes of a set of adjoining triangles; then, a node pairs have been taken into account in order to estimate pollutant stationarity on triangle sides, as well as b node triplets, to statistically associate data from air-monitoring with the corresponding territory area, and c node sextuplets, to assess the impact probability of the outdoor pollutant on indoor environment for each area. Distributions from the various node combinations are all non-Gaussian, in the consequently, Kruskal-Wallis (KW non-parametric statistics has been exploited to test variability on continuous density function from each pair, triplet and sextuplet. Results from the above-mentioned statistical analysis have shown randomness of site selection, which has not allowed a reliable generalization of monitoring data to the entire selected territory, except for a single "forced" case (70%; most important, they suggest a possible procedure to optimize network design.

  7. Statistical concepts a second course

    CERN Document Server

    Lomax, Richard G

    2012-01-01

    Statistical Concepts consists of the last 9 chapters of An Introduction to Statistical Concepts, 3rd ed. Designed for the second course in statistics, it is one of the few texts that focuses just on intermediate statistics. The book highlights how statistics work and what they mean to better prepare students to analyze their own data and interpret SPSS and research results. As such it offers more coverage of non-parametric procedures used when standard assumptions are violated since these methods are more frequently encountered when working with real data. Determining appropriate sample sizes

  8. The Impact of Changing Snowmelt Timing on Non-Irrigated Crop Yield: A Parametric and Non-Parametric Approach

    Science.gov (United States)

    Murray, E. M.; Cobourn, K.; Flores, A. N.; Pierce, J. L.

    2014-12-01

    As climate changes, the final date of spring snowmelt is projected to occur earlier in the year within the western United States. This earlier snowmelt timing may impact crop yield in snow-dominated watersheds by changing the timing of water delivery to agricultural fields. There is considerable uncertainty about how agricultural impacts of snowmelt timing may vary by region, crop-type, and practices like irrigation vs. dryland farming. Establishing the relationship between snowmelt timing and agricultural yield is important for understanding how changes in large-scale climatic indices (like snowmelt date) may be associated with changes in agricultural yield. A better understanding of the influence of changes in snowmelt on non-irrigated crop yield may additionally be extrapolated to better understand how climate change may alter biomass production in non-managed ecosystems. We utilized parametric regression techniques to isolate the magnitude of impact snowmelt timing has had on historical crop yield independently of climate and spatial variables that also impact yield. To do this, we examined the historical relationship between snowmelt timing and non-irrigated wheat and barley yield using a multiple linear regression model to predict yield in several Idaho counties as a function of snowmelt date, climate variables (precipitation and growing degree-days), and spatial differences between counties. We utilized non-parametric techniques to determine where snowmelt timing has positively versus negatively impacted yield. To do this, we developed classification and regression trees to identify spatial controls (e.g. latitude, elevation) on the relationship between snowmelt timing and yield. Most trends suggest a decrease in crop yield with earlier snowmelt, but a significant opposite relationship is observed in some regions of Idaho. An earlier snowmelt date occurring at high latitudes corresponds with higher than average wheat yield. Therefore, Northern Idaho may

  9. Basic assumptions in statistical analyses of data in biomedical ...

    African Journals Online (AJOL)

    If one or more assumptions are violated, an alternative procedure must be used to obtain valid results. This article aims at highlighting some basic assumptions in statistical analyses of data in biomedical sciences. Keywords: samples, independence, non-parametric, parametric, statistical analyses. Int. J. Biol. Chem. Sci. Vol.

  10. Stroke Treatments

    Science.gov (United States)

    ... Month Infographic Stroke Hero F.A.S.T. Quiz Stroke Treatment Stroke used to rank fourth in leading causes of ... type of treatment depends on the type of stroke. Ischemic stroke happens when a clot blocks a ...

  11. On Rigorous Drought Assessment Using Daily Time Scale: Non-Stationary Frequency Analyses, Revisited Concepts, and a New Method to Yield Non-Parametric Indices

    Directory of Open Access Journals (Sweden)

    Charles Onyutha

    2017-10-01

    Full Text Available Some of the problems in drought assessments are that: analyses tend to focus on coarse temporal scales, many of the methods yield skewed indices, a few terminologies are ambiguously used, and analyses comprise an implicit assumption that the observations come from a stationary process. To solve these problems, this paper introduces non-stationary frequency analyses of quantiles. How to use non-parametric rescaling to obtain robust indices that are not (or minimally skewed is also introduced. To avoid ambiguity, some concepts on, e.g., incidence, extremity, etc., were revisited through shift from monthly to daily time scale. Demonstrations on the introduced methods were made using daily flow and precipitation insufficiency (precipitation minus potential evapotranspiration from the Blue Nile basin in Africa. Results show that, when a significant trend exists in extreme events, stationarity-based quantiles can be far different from those when non-stationarity is considered. The introduced non-parametric indices were found to closely agree with the well-known standardized precipitation evapotranspiration indices in many aspects but skewness. Apart from revisiting some concepts, the advantages of the use of fine instead of coarse time scales in drought assessment were given. The links for obtaining freely downloadable tools on how to implement the introduced methods were provided.

  12. The relationship between multilevel models and non-parametric multilevel mixture models: Discrete approximation of intraclass correlation, random coefficient distributions, and residual heteroscedasticity.

    Science.gov (United States)

    Rights, Jason D; Sterba, Sonya K

    2016-11-01

    Multilevel data structures are common in the social sciences. Often, such nested data are analysed with multilevel models (MLMs) in which heterogeneity between clusters is modelled by continuously distributed random intercepts and/or slopes. Alternatively, the non-parametric multilevel regression mixture model (NPMM) can accommodate the same nested data structures through discrete latent class variation. The purpose of this article is to delineate analytic relationships between NPMM and MLM parameters that are useful for understanding the indirect interpretation of the NPMM as a non-parametric approximation of the MLM, with relaxed distributional assumptions. We define how seven standard and non-standard MLM specifications can be indirectly approximated by particular NPMM specifications. We provide formulas showing how the NPMM can serve as an approximation of the MLM in terms of intraclass correlation, random coefficient means and (co)variances, heteroscedasticity of residuals at level 1, and heteroscedasticity of residuals at level 2. Further, we discuss how these relationships can be useful in practice. The specific relationships are illustrated with simulated graphical demonstrations, and direct and indirect interpretations of NPMM classes are contrasted. We provide an R function to aid in implementing and visualizing an indirect interpretation of NPMM classes. An empirical example is presented and future directions are discussed. © 2016 The British Psychological Society.

  13. A Non-Parametric Approach for the Activation Detection of Block Design fMRI Simulated Data Using Self-Organizing Maps and Support Vector Machine.

    Science.gov (United States)

    Bahrami, Sheyda; Shamsi, Mousa

    2017-01-01

    Functional magnetic resonance imaging (fMRI) is a popular method to probe the functional organization of the brain using hemodynamic responses. In this method, volume images of the entire brain are obtained with a very good spatial resolution and low temporal resolution. However, they always suffer from high dimensionality in the face of classification algorithms. In this work, we combine a support vector machine (SVM) with a self-organizing map (SOM) for having a feature-based classification by using SVM. Then, a linear kernel SVM is used for detecting the active areas. Here, we use SOM for feature extracting and labeling the datasets. SOM has two major advances: (i) it reduces dimension of data sets for having less computational complexity and (ii) it is useful for identifying brain regions with small onset differences in hemodynamic responses. Our non-parametric model is compared with parametric and non-parametric methods. We use simulated fMRI data sets and block design inputs in this paper and consider the contrast to noise ratio (CNR) value equal to 0.6 for simulated datasets. fMRI simulated dataset has contrast 1-4% in active areas. The accuracy of our proposed method is 93.63% and the error rate is 6.37%.

  14. Search of significant features in a direct non parametric pattern recognition method. Application to the classification of a multiwire spark chamber picture

    International Nuclear Information System (INIS)

    Buccheri, R.; Coffaro, P.; Di Gesu, V.; Salemi, S.; Colomba, G.

    1975-01-01

    Preliminary results are given of the application of a direct non parametric pattern recognition method to the classification of the pictures of a multiwire spark chamber. The method, developed in an earlier work for an optical spark chamber, looks promising. The picture sample used has with respect to the previous one, the following characteristis: a) the event pictures have a more complicated structure; b) the amount of background sparks in an event is greater; c) there exists a kind of noise which is almost always present in some structured way (double sparkling, bursts...). New features have been used to characterize the event pictures; the results show that the method could be also used as a super filter to reduce the cost of further analysis. (Auth.)

  15. Water quality analysis in rivers with non-parametric probability distributions and fuzzy inference systems: application to the Cauca River, Colombia.

    Science.gov (United States)

    Ocampo-Duque, William; Osorio, Carolina; Piamba, Christian; Schuhmacher, Marta; Domingo, José L

    2013-02-01

    The integration of water quality monitoring variables is essential in environmental decision making. Nowadays, advanced techniques to manage subjectivity, imprecision, uncertainty, vagueness, and variability are required in such complex evaluation process. We here propose a probabilistic fuzzy hybrid model to assess river water quality. Fuzzy logic reasoning has been used to compute a water quality integrative index. By applying a Monte Carlo technique, based on non-parametric probability distributions, the randomness of model inputs was estimated. Annual histograms of nine water quality variables were built with monitoring data systematically collected in the Colombian Cauca River, and probability density estimations using the kernel smoothing method were applied to fit data. Several years were assessed, and river sectors upstream and downstream the city of Santiago de Cali, a big city with basic wastewater treatment and high industrial activity, were analyzed. The probabilistic fuzzy water quality index was able to explain the reduction in water quality, as the river receives a larger number of agriculture, domestic, and industrial effluents. The results of the hybrid model were compared to traditional water quality indexes. The main advantage of the proposed method is that it considers flexible boundaries between the linguistic qualifiers used to define the water status, being the belongingness of water quality to the diverse output fuzzy sets or classes provided with percentiles and histograms, which allows classify better the real water condition. The results of this study show that fuzzy inference systems integrated to stochastic non-parametric techniques may be used as complementary tools in water quality indexing methodologies. Copyright © 2012 Elsevier Ltd. All rights reserved.

  16. Estimation and Testing Based on Data Subject to Measurement Errors: From Parametric to Non-Parametric Likelihood Methods

    Science.gov (United States)

    Vexler, Albert; Tsai, Wan-Min; Malinovsky, Yaakov

    2013-01-01

    Measurement error problems can cause bias or inconsistency of statistical inferences. When investigators are unable to obtain correct measurements of biological assays, special techniques to quantify measurement errors (ME) need to be applied. The sampling based on repeated measurements is a common strategy to allow for ME. This method has been well-addressed in the literature under parametric assumptions. The approach with repeated measures data may not be applicable when the replications are complicated due to cost and/or time concerns. Pooling designs have been proposed as cost-efficient sampling procedures that can assist to provide correct statistical operations based on data subject to ME. We demonstrate that a mixture of both pooled and unpooled data (a hybrid pooled-unpooled design) can support very efficient estimation and testing in the presence of ME. Nonparametric techniques have not been well investigated to analyze repeated measures data or pooled data subject to ME. We propose and examine both the parametric and empirical likelihood methodologies for data subject to ME. We conclude that the likelihood methods based on the hybrid samples are very efficient and powerful. The results of an extensive Monte Carlo study support our conclusions. Real data examples demonstrate the efficiency of the proposed methods in practice. PMID:21805485

  17. A robustness study of parametric and non-parametric tests in model-based multifactor dimensionality reduction for epistasis detection.

    Science.gov (United States)

    Mahachie John, Jestinah M; Van Lishout, François; Gusareva, Elena S; Van Steen, Kristel

    2013-04-25

    Applying a statistical method implies identifying underlying (model) assumptions and checking their validity in the particular context. One of these contexts is association modeling for epistasis detection. Here, depending on the technique used, violation of model assumptions may result in increased type I error, power loss, or biased parameter estimates. Remedial measures for violated underlying conditions or assumptions include data transformation or selecting a more relaxed modeling or testing strategy. Model-Based Multifactor Dimensionality Reduction (MB-MDR) for epistasis detection relies on association testing between a trait and a factor consisting of multilocus genotype information. For quantitative traits, the framework is essentially Analysis of Variance (ANOVA) that decomposes the variability in the trait amongst the different factors. In this study, we assess through simulations, the cumulative effect of deviations from normality and homoscedasticity on the overall performance of quantitative Model-Based Multifactor Dimensionality Reduction (MB-MDR) to detect 2-locus epistasis signals in the absence of main effects. Our simulation study focuses on pure epistasis models with varying degrees of genetic influence on a quantitative trait. Conditional on a multilocus genotype, we consider quantitative trait distributions that are normal, chi-square or Student's t with constant or non-constant phenotypic variances. All data are analyzed with MB-MDR using the built-in Student's t-test for association, as well as a novel MB-MDR implementation based on Welch's t-test. Traits are either left untransformed or are transformed into new traits via logarithmic, standardization or rank-based transformations, prior to MB-MDR modeling. Our simulation results show that MB-MDR controls type I error and false positive rates irrespective of the association test considered. Empirically-based MB-MDR power estimates for MB-MDR with Welch's t-tests are generally lower than those

  18. Design of a completely model free adaptive control in the presence of parametric, non-parametric uncertainties and random control signal delay.

    Science.gov (United States)

    Tutsoy, Onder; Barkana, Duygun Erol; Tugal, Harun

    2018-03-14

    In this paper, an adaptive controller is developed for discrete time linear systems that takes into account parametric uncertainty, internal-external non-parametric random uncertainties, and time varying control signal delay. Additionally, the proposed adaptive control is designed in such a way that it is utterly model free. Even though these properties are studied separately in the literature, they are not taken into account all together in adaptive control literature. The Q-function is used to estimate long-term performance of the proposed adaptive controller. Control policy is generated based on the long-term predicted value, and this policy searches an optimal stabilizing control signal for uncertain and unstable systems. The derived control law does not require an initial stabilizing control assumption as in the ones in the recent literature. Learning error, control signal convergence, minimized Q-function, and instantaneous reward are analyzed to demonstrate the stability and effectiveness of the proposed adaptive controller in a simulation environment. Finally, key insights on parameters convergence of the learning and control signals are provided. Copyright © 2018 ISA. Published by Elsevier Ltd. All rights reserved.

  19. Preventing stroke

    Science.gov (United States)

    ... A.M. Editorial team. Related MedlinePlus Health Topics Hemorrhagic Stroke Ischemic Stroke Stroke Browse the Encyclopedia A.D. ... any medical emergency or for the diagnosis or treatment of any medical condition. A licensed physician should ...

  20. Stroke Rehabilitation

    Science.gov (United States)

    A stroke can cause lasting brain damage. People who survive a stroke need to relearn skills they lost because of ... them relearn those skills. The effects of a stroke depend on which area of the brain was ...

  1. Theoretical remarks on the statistics of three discriminants in Piety's automated signature analysis of PSD [Power Spectral Density] data

    International Nuclear Information System (INIS)

    Behringer, K.; Spiekerman, G.

    1984-01-01

    Piety (1977) proposed an automated signature analysis of power spectral density data. Eight statistical decision discriminants are introduced. For nearly all the discriminants, improved confidence statements can be made. The statistical characteristics of the last three discriminants, which are applications of non-parametric tests, are considered. (author)

  2. Paediatric stroke

    African Journals Online (AJOL)

    2011-04-02

    Apr 2, 2011 ... Ischemic Stroke Registry yielded an incidence of 3.3 cases per 100 000 children per year, of ... Neonatal stroke. The newborn period confers the highest risk period for childhood ischaemic stroke. Focal patterns of ischaemic brain injury to the perinatal brain are .... family history of young stroke/ thrombosis.

  3. Mokken scale analysis of mental health and well-being questionnaire item responses: a non-parametric IRT method in empirical research for applied health researchers

    Directory of Open Access Journals (Sweden)

    Stochl Jan

    2012-06-01

    Full Text Available Abstract Background Mokken scaling techniques are a useful tool for researchers who wish to construct unidimensional tests or use questionnaires that comprise multiple binary or polytomous items. The stochastic cumulative scaling model offered by this approach is ideally suited when the intention is to score an underlying latent trait by simple addition of the item response values. In our experience, the Mokken model appears to be less well-known than for example the (related Rasch model, but is seeing increasing use in contemporary clinical research and public health. Mokken's method is a generalisation of Guttman scaling that can assist in the determination of the dimensionality of tests or scales, and enables consideration of reliability, without reliance on Cronbach's alpha. This paper provides a practical guide to the application and interpretation of this non-parametric item response theory method in empirical research with health and well-being questionnaires. Methods Scalability of data from 1 a cross-sectional health survey (the Scottish Health Education Population Survey and 2 a general population birth cohort study (the National Child Development Study illustrate the method and modeling steps for dichotomous and polytomous items respectively. The questionnaire data analyzed comprise responses to the 12 item General Health Questionnaire, under the binary recoding recommended for screening applications, and the ordinal/polytomous responses to the Warwick-Edinburgh Mental Well-being Scale. Results and conclusions After an initial analysis example in which we select items by phrasing (six positive versus six negatively worded items we show that all items from the 12-item General Health Questionnaire (GHQ-12 – when binary scored – were scalable according to the double monotonicity model, in two short scales comprising six items each (Bech’s “well-being” and “distress” clinical scales. An illustration of ordinal item analysis

  4. Mokken scale analysis of mental health and well-being questionnaire item responses: a non-parametric IRT method in empirical research for applied health researchers.

    Science.gov (United States)

    Stochl, Jan; Jones, Peter B; Croudace, Tim J

    2012-06-11

    Mokken scaling techniques are a useful tool for researchers who wish to construct unidimensional tests or use questionnaires that comprise multiple binary or polytomous items. The stochastic cumulative scaling model offered by this approach is ideally suited when the intention is to score an underlying latent trait by simple addition of the item response values. In our experience, the Mokken model appears to be less well-known than for example the (related) Rasch model, but is seeing increasing use in contemporary clinical research and public health. Mokken's method is a generalisation of Guttman scaling that can assist in the determination of the dimensionality of tests or scales, and enables consideration of reliability, without reliance on Cronbach's alpha. This paper provides a practical guide to the application and interpretation of this non-parametric item response theory method in empirical research with health and well-being questionnaires. Scalability of data from 1) a cross-sectional health survey (the Scottish Health Education Population Survey) and 2) a general population birth cohort study (the National Child Development Study) illustrate the method and modeling steps for dichotomous and polytomous items respectively. The questionnaire data analyzed comprise responses to the 12 item General Health Questionnaire, under the binary recoding recommended for screening applications, and the ordinal/polytomous responses to the Warwick-Edinburgh Mental Well-being Scale. After an initial analysis example in which we select items by phrasing (six positive versus six negatively worded items) we show that all items from the 12-item General Health Questionnaire (GHQ-12)--when binary scored--were scalable according to the double monotonicity model, in two short scales comprising six items each (Bech's "well-being" and "distress" clinical scales). An illustration of ordinal item analysis confirmed that all 14 positively worded items of the Warwick-Edinburgh Mental

  5. Statistical Theory for the "RCT-YES" Software: Design-Based Causal Inference for RCTs. NCEE 2015-4011

    Science.gov (United States)

    Schochet, Peter Z.

    2015-01-01

    This report presents the statistical theory underlying the "RCT-YES" software that estimates and reports impacts for RCTs for a wide range of designs used in social policy research. The report discusses a unified, non-parametric design-based approach for impact estimation using the building blocks of the Neyman-Rubin-Holland causal…

  6. Ischemic Stroke

    Science.gov (United States)

    ... Workplace Giving Fundraise Planned Giving Corporate Giving Cause Marketing Join your team, your way! The Stroke Challenge ... Your Technology Guide High Blood Pressure and Stroke Importance of Physical Activity See More Multimedia Las minorías ...

  7. Stroke - slideshow

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/presentations/100218.htm Stroke - series—Part 1 To use the sharing features ... M. Editorial team. Related MedlinePlus Health Topics Ischemic Stroke A.D.A.M., Inc. is accredited by ...

  8. Statistical trend analysis methods for temporal phenomena

    International Nuclear Information System (INIS)

    Lehtinen, E.; Pulkkinen, U.; Poern, K.

    1997-04-01

    We consider point events occurring in a random way in time. In many applications the pattern of occurrence is of intrinsic interest as indicating a trend or some other systematic feature in the rate of occurrence. The purpose of this report is to survey briefly different statistical trend analysis methods and illustrate their applicability to temporal phenomena in particular. The trend testing of point events is usually seen as the testing of the hypotheses concerning the intensity of the occurrence of events. When the intensity function is parametrized, the testing of trend is a typical parametric testing problem. In industrial applications the operational experience generally does not suggest any specified model and method in advance. Therefore, and particularly, if the Poisson process assumption is very questionable, it is desirable to apply tests that are valid for a wide variety of possible processes. The alternative approach for trend testing is to use some non-parametric procedure. In this report we have presented four non-parametric tests: The Cox-Stuart test, the Wilcoxon signed ranks test, the Mann test, and the exponential ordered scores test. In addition to the classical parametric and non-parametric approaches we have also considered the Bayesian trend analysis. First we discuss a Bayesian model, which is based on a power law intensity model. The Bayesian statistical inferences are based on the analysis of the posterior distribution of the trend parameters, and the probability of trend is immediately seen from these distributions. We applied some of the methods discussed in an example case. It should be noted, that this report is a feasibility study rather than a scientific evaluation of statistical methods, and the examples can only be seen as demonstrations of the methods

  9. Practical statistics in pain research.

    Science.gov (United States)

    Kim, Tae Kyun

    2017-10-01

    Pain is subjective, while statistics related to pain research are objective. This review was written to help researchers involved in pain research make statistical decisions. The main issues are related with the level of scales that are often used in pain research, the choice of statistical methods between parametric or nonparametric statistics, and problems which arise from repeated measurements. In the field of pain research, parametric statistics used to be applied in an erroneous way. This is closely related with the scales of data and repeated measurements. The level of scales includes nominal, ordinal, interval, and ratio scales. The level of scales affects the choice of statistics between parametric or non-parametric methods. In the field of pain research, the most frequently used pain assessment scale is the ordinal scale, which would include the visual analogue scale (VAS). There used to be another view, however, which considered the VAS to be an interval or ratio scale, so that the usage of parametric statistics would be accepted practically in some cases. Repeated measurements of the same subjects always complicates statistics. It means that measurements inevitably have correlations between each other, and would preclude the application of one-way ANOVA in which independence between the measurements is necessary. Repeated measures of ANOVA (RMANOVA), however, would permit the comparison between the correlated measurements as long as the condition of sphericity assumption is satisfied. Conclusively, parametric statistical methods should be used only when the assumptions of parametric statistics, such as normality and sphericity, are established.

  10. Statistical reliability analyses of two wood plastic composite extrusion processes

    International Nuclear Information System (INIS)

    Crookston, Kevin A.; Mark Young, Timothy; Harper, David; Guess, Frank M.

    2011-01-01

    Estimates of the reliability of wood plastic composites (WPC) are explored for two industrial extrusion lines. The goal of the paper is to use parametric and non-parametric analyses to examine potential differences in the WPC metrics of reliability for the two extrusion lines that may be helpful for use by the practitioner. A parametric analysis of the extrusion lines reveals some similarities and disparities in the best models; however, a non-parametric analysis reveals unique and insightful differences between Kaplan-Meier survival curves for the modulus of elasticity (MOE) and modulus of rupture (MOR) of the WPC industrial data. The distinctive non-parametric comparisons indicate the source of the differences in strength between the 10.2% and 48.0% fractiles [3,183-3,517 MPa] for MOE and for MOR between the 2.0% and 95.1% fractiles [18.9-25.7 MPa]. Distribution fitting as related to selection of the proper statistical methods is discussed with relevance to estimating the reliability of WPC. The ability to detect statistical differences in the product reliability of WPC between extrusion processes may benefit WPC producers in improving product reliability and safety of this widely used house-decking product. The approach can be applied to many other safety and complex system lifetime comparisons.

  11. Cryptogenic Stroke

    Directory of Open Access Journals (Sweden)

    Mohammad Saadatnia

    2017-02-01

    Full Text Available Cryptogenic stroke is defined as brain infarction that is not attributable to a source of definite embolism, large artery atherosclerosis, or small artery disease despite a thorough vascular, cardiac, and serologic evaluation. Despite many advances in our understanding of ischemic stroke, cryptogenic strokes remain a diagnostic and therapeutic challenge. The pathophysiology of cryptogenic stroke is likely various. Probable mechanisms include cardiac embolism secondary to occult paroxysmal atrial fibrillation, aortic atheromatous disease or other cardiac sources, paradoxical embolism from atrial septal abnormalities such as patent foramen ovale, hypercoagulable states, and preclinical or subclinical cerebrovascular disease.  Cryptogenic stroke is one-fourth among cerebral infarction, but most of them could be ascribed to embolic stroke. A significant proportion of cryptogenic strokes adhere to embolic infarct topography on brain imaging and improvement in our ability to detect paroxysmal atrial fibrillation in patients with cryptogenic stroke has strengthened the idea that these strokes are embolic in nature. a significant proportion of cryptogenic strokes adhere to embolic infarct topography on brain imaging.embolic stroke of undetermined sources(ESUS was planned for unifying embolic stroke of undetermined source.  The etiologies underlying ESUS included minor-risk potential cardioembolic sources, covert paroxysmal atrial fibrillation, cancer-associated coagulopathy and embolism, arteriogenic emboli, and paroxysmal embolism. Extensive evaluation including transesophageal echocardiography and cardiac monitoring for long time could identify the etiology of these patients. Therefore cryptogenic stroke is a diagnosis of exclusion. Compared with other stroke subtypes, cryptogenic stroke tends to have a better prognosis and lower long-term risk of recurrence.

  12. Quantitative Phylogenomics of Within-Species Mitogenome Variation: Monte Carlo and Non-Parametric Analysis of Phylogeographic Structure among Discrete Transatlantic Breeding Areas of Harp Seals (Pagophilus groenlandicus).

    Science.gov (United States)

    Carr, Steven M; Duggan, Ana T; Stenson, Garry B; Marshall, H Dawn

    2015-01-01

    -stone biogeographic models, but not a simple 1-step trans-Atlantic model. Plots of the cumulative pairwise sequence difference curves among seals in each of the four populations provide continuous proxies for phylogenetic diversification within each. Non-parametric Kolmogorov-Smirnov (K-S) tests of maximum pairwise differences between these curves indicates that the Greenland Sea population has a markedly younger phylogenetic structure than either the White Sea population or the two Northwest Atlantic populations, which are of intermediate age and homogeneous structure. The Monte Carlo and K-S assessments provide sensitive quantitative tests of within-species mitogenomic phylogeography. This is the first study to indicate that the White Sea and Greenland Sea populations have different population genetic histories. The analysis supports the hypothesis that Harp Seals comprises three genetically distinguishable breeding populations, in the White Sea, Greenland Sea, and Northwest Atlantic. Implications for an ice-dependent species during ongoing climate change are discussed.

  13. Statistical analysis applied to safety culture self-assessment

    International Nuclear Information System (INIS)

    Macedo Soares, P.P.

    2002-01-01

    Interviews and opinion surveys are instruments used to assess the safety culture in an organization as part of the Safety Culture Enhancement Programme. Specific statistical tools are used to analyse the survey results. This paper presents an example of an opinion survey with the corresponding application of the statistical analysis and the conclusions obtained. Survey validation, Frequency statistics, Kolmogorov-Smirnov non-parametric test, Student (T-test) and ANOVA means comparison tests and LSD post-hoc multiple comparison test, are discussed. (author)

  14. Statistical analysis plan for the EuroHYP-1 trial: European multicentre, randomised, phase III clinical trial of the therapeutic hypothermia plus best medical treatment versus best medical treatment alone for acute ischaemic stroke.

    Science.gov (United States)

    Winkel, Per; Bath, Philip M; Gluud, Christian; Lindschou, Jane; van der Worp, H Bart; Macleod, Malcolm R; Szabo, Istvan; Durand-Zaleski, Isabelle; Schwab, Stefan

    2017-11-29

    Cooling may reduce infarct size and improve neurological outcomes in patients with ischaemic stroke. In phase II trials, cooling awake patients with ischaemic stroke has been shown to be feasible and safe, but the effects in functional outcomes has not yet been investigated in an adequately sized randomised clinical trial. The EuroHYP-1 trial is a multinational, randomised, superiority phase III clinical trial with masked outcome assessment testing the benefits and harms of therapeutic cooling in awake adult patients with acute ischaemic stroke. The outcomes dealt with here include the primary outcome the Rankin score (mRS) at day 91 +/-14 days after randomisation. The secondary and exploratory outcomes at day 91 +/-14 days unless otherwise stated encompassing: (1) death or dependency, defined as mRS score > 2; (2) death; (3) National Institutes of Health Stroke Score; (4) brain infarct size at 48 +/-24 hours; (5) EQ-5D-5 L score, and (6) WHODAS 2.0 score. Other outcomes are: the primary safety outcome serious adverse events; and the incremental cost-effectiveness, and cost utility ratios. The analysis sets include (1) the intention-to-treat population, and (2) the per protocol population. The sample size is estimated to 800 patients (5% type 1 and 20% type 2 errors). All analyses are adjusted for the protocol-specified stratification variables (nationality of centre), and the minimisation variables. In the analysis, we use ordinal regression (the primary outcome), logistic regression (binary outcomes), general linear model (continuous outcomes), and the Poisson or negative binomial model (rate outcomes). Major adjustments compared with the original statistical analysis plan encompass: (1) adjustment of analyses by nationality; (2) power calculations for the secondary outcomes; (3) to address the multiplicity problem using of a fixed-sequence testing procedure starting with the primary outcome followed by the secondary outcomes ordered according to falling

  15. Statistical Analysis of Data for Timber Strengths

    DEFF Research Database (Denmark)

    Sørensen, John Dalsgaard; Hoffmeyer, P.

    . The statistical fits have generally been made using all data (100%) and the lower tail (30%) of the data. The Maximum Likelihood Method and the Least Square Technique have been used to estimate the statistical parameters in the selected distributions. 8 different databases are analysed. The results show that 2......Statistical analyses are performed for material strength parameters from approximately 6700 specimens of structural timber. Non-parametric statistical analyses and fits to the following distributions types have been investigated: Normal, Lognormal, 2 parameter Weibull and 3-parameter Weibull......-parameter Weibull (and Normal) distributions give the best fits to the data available, especially if tail fits are used whereas the LogNormal distribution generally gives poor fit and larger coefficients of variation, especially if tail fits are used....

  16. Statistical Analysis of Data for Timber Strengths

    DEFF Research Database (Denmark)

    Sørensen, John Dalsgaard

    2003-01-01

    Statistical analyses are performed for material strength parameters from a large number of specimens of structural timber. Non-parametric statistical analysis and fits have been investigated for the following distribution types: Normal, Lognormal, 2 parameter Weibull and 3-parameter Weibull....... The statistical fits have generally been made using all data and the lower tail of the data. The Maximum Likelihood Method and the Least Square Technique have been used to estimate the statistical parameters in the selected distributions. The results show that the 2-parameter Weibull distribution gives the best...... fits to the data available, especially if tail fits are used whereas the Log Normal distribution generally gives a poor fit and larger coefficients of variation, especially if tail fits are used. The implications on the reliability level of typical structural elements and on partial safety factors...

  17. Recovering after stroke

    Science.gov (United States)

    Stroke rehabilitation; Cerebrovascular accident - rehabilitation; Recovery from stroke; Stroke - recovery; CVA - recovery ... LIVE AFTER A STROKE Most people will need stroke rehabilitation (rehab) to help them recover after they leave ...

  18. Stroke Rehabilitation

    Science.gov (United States)

    ... unique for each person. Although a majority of functional abilities may be restored soon after a stroke, recovery is an ongoing process. Effects of a Stroke Weakness (hemiparesis) or paralysis (hemiplegia) on one side of the body that may affect the whole ...

  19. Pediatric Stroke

    Science.gov (United States)

    ... of 3 and 10. In those with SCD, ischemic strokes most often occur in children under the age of 15 and adults over the age of 30, while hemorrhagic strokes most often occur in young adults between the ages of 20 and 30. ...

  20. Stroke and Cerebrovascular Diseases Registry

    Science.gov (United States)

    2017-09-11

    Stroke; Acute Stroke; Acute Brain Injury; Ischemic Stroke; Hemorrhagic Stroke; Transient Ischemic Attack; Subarachnoid Hemorrhage; Cerebral Ischemia; Cerebral Infarction; Cerebral Stroke; Venous Sinus Thrombosis, Cranial

  1. Depression screening in stroke: a comparison of alternative measures with the structured diagnostic interview for the diagnostic and statistical manual of mental disorders, fourth edition (major depressive episode) as criterion standard.

    Science.gov (United States)

    Turner, Alyna; Hambridge, John; White, Jennifer; Carter, Gregory; Clover, Kerrie; Nelson, Louise; Hackett, Maree

    2012-04-01

    Screening tools for depression and psychological distress commonly used in medical settings have not been well validated in stroke populations. We aimed to determine the accuracy of common screening tools for depression or distress in detecting caseness for a major depressive episode compared with a clinician-administered structured clinical interview for Diagnostic and Statistical Manual of Mental Disorders Fourth Edition as the gold standard. Seventy-two participants ≥3 weeks poststroke underwent a diagnostic interview for major depressive episode and completed the Patient Health Questionnaire-2 and -9, Hospital Anxiety and Depression Scale, Beck Depression Inventory-II, Distress Thermometer, and Kessler-10. Internal consistency, sensitivity, specificity, likelihood ratios, and posttest probabilities were calculated. Each measure was validated against the gold standard using receiver operating characteristic curves with comparison of the area under the curve for all measures. Internal consistency ranged from acceptable to excellent for all measures (Cronbach α=0.78-0.94). Areas under the curve (95% CI) for the Patient Health Questionnaire-2, Patient Health Questionnaire-9, Hospital Anxiety and Depression Scale depression and total score, Beck Depression Inventory-II, and Kessler-10 ranged from 0.80 (0.69-0.89) for the Kessler-10 to 0.89 (0.79-0.95) for the Beck Depression Inventory-II with no significant differences between measures. The Distress Thermometer had an area under the curve (95% CI) of 0.73 (0.61-0.83), significantly smaller than the Beck Depression Inventory-II (P<0.05). Apart from the Distress Thermometer, selected scales performed adequately in a stroke population with no significant difference between measures. The Patient Health Questionnaire-2 would be the most useful single screen given free availability and the shortest number of items.

  2. Stroke Care 2: Stroke rehabilitation

    NARCIS (Netherlands)

    Langhorne, P.; Bernhardt, J.; Kwakkel, G.

    2011-01-01

    Stroke is a common, serious, and disabling global health-care problem, and rehabilitation is a major part of patient care. There is evidence to support rehabilitation in well coordinated multidisciplinary stroke units or through provision of early supported provision of discharge teams. Potentially

  3. Machine learning and statistical techniques : an application to the prediction of insolvency in Spanish non-life insurance companies

    OpenAIRE

    Díaz, Zuleyka; Segovia, María Jesús; Fernández, José

    2005-01-01

    Prediction of insurance companies insolvency has arisen as an important problem in the field of financial research. Most methods applied in the past to tackle this issue are traditional statistical techniques which use financial ratios as explicative variables. However, these variables often do not satisfy statistical assumptions, which complicates the application of the mentioned methods. In this paper, a comparative study of the performance of two non-parametric machine learning techniques ...

  4. Pediatric stroke

    International Nuclear Information System (INIS)

    Hoermann, M.

    2008-01-01

    Stroke in childhood has gained increasingly more attention and is accepted as an important disease in childhood. The reasons for this severe event and the consequences for the rest of the life are totally different than for adults. This is also true for the diagnosis and therapy. This paper gives a comprehensive overview on the characteristics of pediatric stroke to assist radiologists in making a rapid and safe diagnosis in order to identify the underlying disease. (orig.) [de

  5. Driving After a Stroke

    Science.gov (United States)

    ... Stroke Association.org Professionals for Stroke Association.org Shop for Stroke Association.org Support for Stroke Association. ... a wheelchair accessible or modified van, truck or car can provide the assurance you need to feel ...

  6. Quantum statistical inference for density estimation

    Energy Technology Data Exchange (ETDEWEB)

    Silver, R.N.; Martz, H.F.; Wallstrom, T.

    1993-11-01

    A new penalized likelihood method for non-parametric density estimation is proposed, which is based on a mathematical analogy to quantum statistical physics. The mathematical procedure for density estimation is related to maximum entropy methods for inverse problems; the penalty function is a convex information divergence enforcing global smoothing toward default models, positivity, extensivity and normalization. The novel feature is the replacement of classical entropy by quantum entropy, so that local smoothing may be enforced by constraints on the expectation values of differential operators. Although the hyperparameters, covariance, and linear response to perturbations can be estimated by a variety of statistical methods, we develop the Bayesian interpretation. The linear response of the MAP estimate is proportional to the covariance. The hyperparameters are estimated by type-II maximum likelihood. The method is demonstrated on standard data sets.

  7. Applications of quantum entropy to statistics

    International Nuclear Information System (INIS)

    Silver, R.N.; Martz, H.F.

    1994-01-01

    This paper develops two generalizations of the maximum entropy (ME) principle. First, Shannon classical entropy is replaced by von Neumann quantum entropy to yield a broader class of information divergences (or penalty functions) for statistics applications. Negative relative quantum entropy enforces convexity, positivity, non-local extensivity and prior correlations such as smoothness. This enables the extension of ME methods from their traditional domain of ill-posed in-verse problems to new applications such as non-parametric density estimation. Second, given a choice of information divergence, a combination of ME and Bayes rule is used to assign both prior and posterior probabilities. Hyperparameters are interpreted as Lagrange multipliers enforcing constraints. Conservation principles are proposed to act statistical regularization and other hyperparameters, such as conservation of information and smoothness. ME provides an alternative to heirarchical Bayes methods

  8. Common descriptive and analytical statistics in investigative studies

    International Nuclear Information System (INIS)

    Ettarh, R.

    2004-01-01

    Statistics is used in many investigative studies. This paper provides a description of a few of the commonly used statistical parameters in such studies and tries to exclude some of the technical terminology that is frequently associated with the explanation of statistical testing of data. The mean, standard deviation, standard error of the mean and the concept of probability are explained as the usefulness of parametric and non-parametric attributes and testing of data, and analysis of variance (ANOVA). Without attempting to be exhaustive as a simple source of information on statistical terminology, these descriptions are presented in an easy-to-understand manner in order to aid an understanding and appreciation of the usefulness of statistics in the evaluation of data. The information presented here should not be regarded as a substitute for proper sources of information on statistics

  9. Cognitive performance after ischaemic stroke

    Directory of Open Access Journals (Sweden)

    Maria Gabriela R. Ferreira

    Full Text Available Cognitive impairment after stroke affects the patient recovery process. Therefore, the identification of factors associated with cognitive outcomes is important since it allows risk profiles of stroke survivors to be determined. OBJECTIVE: To assess cognitive outcome of stroke outpatients and investigate associations among clinical and demographic variables, vascular risk factors, depression symptoms and functional ability; and to describe the neuropsychological profile of these patients. METHODS: A cross-sectional design study was conducted. Subjects who suffered a first-ever ischaemic stroke 6 to 10 months prior to data collection underwent neuropsychological assessment and screening for depressive symptoms and functional ability. The outcome "cognitive performance" was analyzed considering two groups: "cognitive impairment" and "no cognitive impairment". RESULTS: There was a statistically significant association between cognitive impairment and female gender, age, stroke severity and functional ability. Regarding neuropsychological profile, the cognitive impairment group exhibited more generalized deficits in attention, visuospatial organization, verbal functions and verbal memory domains compared to the community control group. CONCLUSION: The occurrence of cognitive impairment among patients was high, especially in women, older participants, individuals with more severe stroke, and greater impairment in functional ability. Multiple cognitive domains are affected and this may hamper recovery and negatively impact independence and quality of life after stroke.

  10. Data and Statistics: Women and Heart Disease

    Science.gov (United States)

    ... Summary Coverdell Program 2012-2015 State Summaries Data & Statistics Fact Sheets Heart Disease and Stroke Fact Sheets ... Roadmap for State Planning Other Data Resources Other Statistic Resources Grantee Information Cross-Program Information Online Tools ...

  11. Use of statistical tests and statistical software choice in 2014: tale from three Medline indexed Pakistani journals.

    Science.gov (United States)

    Shaikh, Masood Ali

    2016-04-01

    Statistical tests help infer meaningful conclusions from studies conducted and data collected. This descriptive study analyzed the type of statistical tests used and the statistical software utilized for analysis reported in the original articles published in 2014 by the three Medline-indexed journals of Pakistan. Cumulatively, 466 original articles were published in 2014. The most frequently reported statistical tests for original articles by all three journals were bivariate parametric and non-parametric tests i.e. involving comparisons between two groups e.g. Chi-square test, t-test, and various types of correlations. Cumulatively, 201 (43.1%) articles used these tests. SPSS was the primary choice for statistical analysis, as it was exclusively used in 374 (80.3%) original articles. There has been a substantial increase in the number of articles published, and in the sophistication of statistical tests used in the articles published in the Pakistani Medline indexed journals in 2014, compared to 2007.

  12. Heat Stroke

    DEFF Research Database (Denmark)

    Mørch, Sofie Søndergaard; Andersen, Johnny Dohn Holmgren; Bestle, Morten Heiberg

    2017-01-01

    and mortality. This case report describes two Danish patients diagnosed with heat stroke syndrome during a heat wave in the summer of 2014. Both patients were morbidly obese and had several predisposing illnesses. However since heat stroke is a rare condition in areas with temperate climate, they were...... not diagnosed until several days after admittance; hence treatment with cooling was delayed. Both patients were admitted to the intensive care unit, where they were treated with an external cooling device and received treatment for complications. Both cases ended fatally. As global warming continues, more heat...

  13. Understanding Statistics - Cancer Statistics

    Science.gov (United States)

    Annual reports of U.S. cancer statistics including new cases, deaths, trends, survival, prevalence, lifetime risk, and progress toward Healthy People targets, plus statistical summaries for a number of common cancer types.

  14. Parametric and non-parametric approaches to assess spatial variability of As and F- concentrations in uncertain geological settings of Tanzania.

    Science.gov (United States)

    Ijumulana, Julian; Bhattacharya, Prosun; Ligate, Fanuel J.; Irunde, Regina; Mtalo, Felix

    2017-04-01

    Groundwater pollution is becoming a serious problem to human health worldwide and affects sustainable Water Quality Management Plan in many countries. The occurrence of such pollutants can either be geogenic or anthropogenic of which geogenic pollutants are reported to be more dangerous due to uncertainty in their occurrence, interaction with groundwater and how they affect human health through drinking water supplies. Therefore, understanding the spatial variability of groundwater As and F concentrations is a critical issue to be considered in developing a sustainable Water Quality Management Plan in any country. In northern parts of Tanzania, due to lack of alternative drinking water sources, adjurisdiction and insufficient technology to detect and remove or lower pollutants concentrations, the maximum permissible concentration has been set to 4 mg/L and 0.05 mg/L for F and As respectively, contrary to the WHO drinking water guideline values of 1.5 mg/L F and 0.01mg/L As. The current study on groundwater contamination in Tanzania is focused on understanding the spatial variability of F and As concentrations and characterising regions with high concentrations that do not comply with drinking water guidelines. Due to limited data coverage, we are using both stochastic and nonparametric statistical approaches to understand their spatial distribution and associated uncertainty. In parametric approaches, we are developing geostatistical methods based on regression kriging (RK) and simulations to generate a series of images showing spatial distribution of As and F concentrations based on sample data. In nonparametric methods we are using ranked sums approaches to assess the relationship between detected concentrations in shallow wells, springs, boreholes, deep shallow wells and rivers in different geological settings. The resulting simulation images are classified using rule-based classifier to detect contaminated and uncontaminated areas and associated model of

  15. Stroke awareness in Denmark

    DEFF Research Database (Denmark)

    Truelsen, Thomas; Krarup, Lars-Henrik

    2010-01-01

    This is the first study to examine the awareness of major stroke symptoms and stroke risk factors among the general population in Denmark. Early recognition of stroke warning signs and means of reducing stroke occurrence could improve the treatment and prevention of stroke....

  16. A virtual reality system integrated with robot-assisted haptics to simulate pinch-grip task: Motor ingredients for the assessment in chronic stroke.

    Science.gov (United States)

    Yeh, Shih-Ching; Lee, Si-Huei; Chan, Rai-Chi; Chen, Shuya; Rizzo, Albert

    2014-01-01

    Among numerous studies on virtual reality (VR) technology for motor rehabilitation, the majorities have only used it as a motor training system and did not use the kinematic or kinetic information obtained as the basis for therapeutic effect assessment. Incorporating the kinematic and kinetic information acquired through a robot-assisted VR system on pinch-grip training, this study intends to propose novel motor ingredients represented as indices for the interpretation of motor behaviors and verify the efficacy of them for the assessment in chronic stroke. Clinical trials were conducted on eight stroke patients and clinical assessments were made as the objective standard. Non-parametric test and correlation analysis were performed on results of motor indices and clinical assessments. Non-parametric test indicated that 50% of the motor indices significantly improved while the others showed a trend of improvement, consisting with the findings in clinical assessments. Correlation analysis showed that the three clinical assessment items were correlated to items in the motor ingredients. The proposed motor ingredients gathered from the robot-assisted VR training system were able to contribute to the assessment of therapeutic effect in chronic stroke and were capable for the interpretation of behavior phases.

  17. Functional summary statistics for the Johnson-Mehl model

    DEFF Research Database (Denmark)

    Møller, Jesper; Ghorbani, Mohammad

    The Johnson-Mehl germination-growth model is a spatio-temporal point process model which among other things have been used for the description of neurotransmitters datasets. However, for such datasets parametric Johnson-Mehl models fitted by maximum likelihood have yet not been evaluated by means...... of functional summary statistics. This paper therefore invents four functional summary statistics adapted to the Johnson-Mehl model, with two of them based on the second-order properties and the other two on the nuclei-boundary distances for the associated Johnson-Mehl tessellation. The functional summary...... statistics theoretical properties are investigated, non-parametric estimators are suggested, and their usefulness for model checking is examined in a simulation study. The functional summary statistics are also used for checking fitted parametric Johnson-Mehl models for a neurotransmitters dataset....

  18. Stroke rehabilitation.

    Science.gov (United States)

    Langhorne, Peter; Bernhardt, Julie; Kwakkel, Gert

    2011-05-14

    Stroke is a common, serious, and disabling global health-care problem, and rehabilitation is a major part of patient care. There is evidence to support rehabilitation in well coordinated multidisciplinary stroke units or through provision of early supported provision of discharge teams. Potentially beneficial treatment options for motor recovery of the arm include constraint-induced movement therapy and robotics. Promising interventions that could be beneficial to improve aspects of gait include fitness training, high-intensity therapy, and repetitive-task training. Repetitive-task training might also improve transfer functions. Occupational therapy can improve activities of daily living; however, information about the clinical effect of various strategies of cognitive rehabilitation and strategies for aphasia and dysarthria is scarce. Several large trials of rehabilitation practice and of novel therapies (eg, stem-cell therapy, repetitive transcranial magnetic stimulation, virtual reality, robotic therapies, and drug augmentation) are underway to inform future practice. Copyright © 2011 Elsevier Ltd. All rights reserved.

  19. Multiple Strokes

    Directory of Open Access Journals (Sweden)

    Obododimma Oha

    2008-12-01

    Full Text Available This poem playfully addresses the slippery nature of linguistic signification, employing humour and sarcasm in presenting a wide range of human experience. It ironical twists -- and "strokes" (read ambiguously as both a giving a punishment and erotic pleasuring -- move from the naming of location through international discourse of capital to the crumbling relationships between nation states. It reading of the signs of language is tied to the unease and fracture in cultural and political experience.

  20. Preventing Stroke Deaths

    Science.gov (United States)

    ... die within minutes. Strokes happen more in some populations and geographic areas. Stroke death declines have stalled in 3 out of every 4 states. Blacks have the highest stroke death rates among all ...

  1. Two Kinds of Stroke

    Science.gov (United States)

    ... Issue Past Issues Special Section Two Kinds of Stroke Past Issues / Summer 2007 Table of Contents For ... are often a warning sign for future strokes. Stroke Can Affect Anyone Award-winning actress Julie Harris ...

  2. Healthy Living after Stroke

    Science.gov (United States)

    ... Stories Stroke Heroes Among Us Healthy Living After Stroke Nutrition Good nutrition is one way to reduce ... the hospital. Thank goodness, she did. Subscribe to Stroke Connection Get quarterly digital issues plus our monthly ...

  3. Parametric and Non-Parametric System Modelling

    DEFF Research Database (Denmark)

    Nielsen, Henrik Aalborg

    1999-01-01

    considered. It is shown that adaptive estimation in conditional parametric models can be performed by combining the well known methods of local polynomial regression and recursive least squares with exponential forgetting. The approach used for estimation in conditional parametric models also highlights how...... of a linear model are estimated as functions of some explanatory variable(s). Also, software for handling the estimation is presented. The software runs under S-PLUS and R and contains also a number of tools useful when doing model diagnostics or interpreting the results. Adaptive estimation is also...... networks is included. In this paper, neural networks are used for predicting the electricity production of a wind farm. The results are compared with results obtained using an adaptively estimated ARX-model. Finally, two papers on stochastic differential equations are included. In the first paper, among...

  4. Non-Parametric Model Drift Detection

    Science.gov (United States)

    2016-07-01

    Y_j): 0.246 12:criminal,justice,crimes,crime,prosecutor,judicial,judges, prison ,acts,prosecution Group num: 13, TC(X;Y_j): 0.233 13:weapons,nuclear...decla ration,res Group num: 43, TC(X;Y_j): 0.081 43:germany,france,costa,canada,rica,japan,italy,netherlands,australia, norway Group num: 44, TC(X;Y_j

  5. Understanding Life After Stroke

    OpenAIRE

    Hjelmblink, Finn

    2008-01-01

    Stroke is an acute, neurological dysfunction of vascular origin with sudden occurrence and it influences physical, cognitive and psychological functions. Initial treatment aims at eliminating or reducing the brain damage. Soon, however, the influence of the stroke on the entire life of stroke survivors has to be considered. This thesis explores the meaning of life after stroke to 19 elderly stroke survivors during the first year post stroke. Survivors were interviewed twice and the interviews...

  6. Difficulty Swallowing After Stroke (Dysphagia)

    Science.gov (United States)

    ... Simple Techniques Can Help Memory after a Stroke Self-Esteem after Stroke Cognitive Challenges After Stroke Depression Trumps ... spasticity), fatigue and more. Let's Talk About Stroke Fact Sheets Our stroke fact sheets cover treatments, recovery, ...

  7. Empirical validation of statistical parametric mapping for group imaging of fast neural activity using electrical impedance tomography.

    Science.gov (United States)

    Packham, B; Barnes, G; Dos Santos, G Sato; Aristovich, K; Gilad, O; Ghosh, A; Oh, T; Holder, D

    2016-06-01

    Electrical impedance tomography (EIT) allows for the reconstruction of internal conductivity from surface measurements. A change in conductivity occurs as ion channels open during neural activity, making EIT a potential tool for functional brain imaging. EIT images can have  >10 000 voxels, which means statistical analysis of such images presents a substantial multiple testing problem. One way to optimally correct for these issues and still maintain the flexibility of complicated experimental designs is to use random field theory. This parametric method estimates the distribution of peaks one would expect by chance in a smooth random field of a given size. Random field theory has been used in several other neuroimaging techniques but never validated for EIT images of fast neural activity, such validation can be achieved using non-parametric techniques. Both parametric and non-parametric techniques were used to analyze a set of 22 images collected from 8 rats. Significant group activations were detected using both techniques (corrected p  <  0.05). Both parametric and non-parametric analyses yielded similar results, although the latter was less conservative. These results demonstrate the first statistical analysis of such an image set and indicate that such an analysis is an approach for EIT images of neural activity.

  8. Heritability of young- and old-onset ischaemic stroke.

    Science.gov (United States)

    Bluher, A; Devan, W J; Holliday, E G; Nalls, M; Parolo, S; Bione, S; Giese, A K; Boncoraglio, G B; Maguire, J M; Müller-Nurasyid, M; Gieger, C; Meschia, J F; Rosand, J; Rolfs, A; Kittner, S J; Mitchell, B D; O'Connell, J R; Cheng, Y C

    2015-11-01

    Although the genetic contribution to stroke risk is well known, it remains unclear if young-onset stroke has a stronger genetic contribution than old-onset stroke. This study aims to compare the heritability of ischaemic stroke risk between young and old, using common genetic variants from whole-genome array data in population-based samples. This analysis included 4050 ischaemic stroke cases and 5765 controls from six study populations of European ancestry; 47% of cases were young-onset stroke (age stroke risk in these unrelated individuals, the pairwise genetic relatedness was estimated between individuals based on their whole-genome array data using a mixed linear model. Heritability was estimated separately for young-onset stroke and old-onset stroke (age ≥ 55 years). Heritabilities for young-onset stroke and old-onset stroke were estimated at 42% (±8%, P genetic contribution to the risk of stroke may be higher in young-onset ischaemic stroke, although the difference was not statistically significant. © 2015 EAN.

  9. Prevention Of Stroke

    Directory of Open Access Journals (Sweden)

    Nagaraja D

    2005-01-01

    Full Text Available Stroke is an important cause for neurological morbidity and mortality. Prevention of ischemic stroke involves identification and prevention of risk factors and optimal use of pharmacotherapy. Risk factors have been classified as modifiable and non-modifiable; control of modifiable factors should prevent stroke occurrence. Stroke prevention has been described at three levels: primary, secondary and tertiary. Prolonged hypertension increases an individual′s risk for developing fatal or nonfatal stroke by three times and its control has been shown to prevent stroke. Diabetes mellitus is an important cause for microangiopathy and predisposes to stroke. Statin trials have shown significant reduction in stroke in those who were treated with statins. Stroke risk can be reduced by avoiding tobacco use, control of obesity and avoiding sedentary life style. Anti platelet medications are effective for secondary prevention of stroke. Educating society regarding modifiable risk factors and optimal use of pharmacotherapy form the cornerstone for the prevention of stroke.

  10. Visual attention in posterior stroke

    DEFF Research Database (Denmark)

    Fabricius, Charlotte; Petersen, Anders; Iversen, Helle K

    Objective: Impaired visual attention is common following strokes in the territory of the middle cerebral artery, particularly in the right hemisphere. However, attentional effects of more posterior lesions are less clear. The aim of this study was to characterize visual processing speed...... and apprehension span following posterior cerebral artery (PCA) stroke. We also relate these attentional parameters to visual word recognition, as previous studies have suggested that reduced visual speed and span may explain pure alexia. Methods: Nine patients with MR-verified focal lesions in the PCA......-territory (four left PCA; four right PCA; one bilateral, all >1 year post stroke) were compared to 25 controls using single case statistics. Visual attention was characterized by a whole report paradigm allowing for hemifield-specific speed and span measurements. We also characterized visual field defects...

  11. Log-concave Probability Distributions: Theory and Statistical Testing

    DEFF Research Database (Denmark)

    An, Mark Yuing

    1996-01-01

    This paper studies the broad class of log-concave probability distributions that arise in economics of uncertainty and information. For univariate, continuous, and log-concave random variables we prove useful properties without imposing the differentiability of density functions. Discrete...... and multivariate distributions are also discussed. We propose simple non-parametric testing procedures for log-concavity. The test statistics are constructed to test one of the two implicati ons of log-concavity: increasing hazard rates and new-is-better-than-used (NBU) property. The test for increasing hazard...... rates are based on normalized spacing of the sample order statistics. The tests for NBU property fall into the category of Hoeffding's U-statistics...

  12. Piracetam for acute ischaemic stroke.

    Science.gov (United States)

    Ricci, Stefano; Celani, Maria Grazia; Cantisani, Teresa Anna; Righetti, Enrico

    2012-09-12

    Piracetam has neuroprotective and antithrombotic effects that may help to reduce death and disability in people with acute stroke. This is an update of a Cochrane Review first published in 1999, and previously updated in 2006 and 2009. To assess the effects of piracetam in acute, presumed ischaemic stroke. We searched the Cochrane Stroke Group Trials Register (last searched 15 May 2011), the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2011, Issue 2), MEDLINE (1966 to May 2011), EMBASE (1980 to May 2011), and ISI Science Citation Index (1981 to May 2011). We also contacted the manufacturer of piracetam to identify further published and unpublished studies. Randomised trials comparing piracetam with control, with at least mortality reported and entry to the trial within three days of stroke onset. Two review authors extracted data and assessed trial quality and this was checked by the other two review authors. We contacted study authors for missing information. We included three trials involving 1002 patients, with one trial contributing 93% of the data. Participants' ages ranged from 40 to 85 years, and both sexes were equally represented. Piracetam was associated with a statistically non-significant increase in death at one month (approximately 31% increase, 95% confidence interval 81% increase to 5% reduction). This trend was no longer apparent in the large trial after correction for imbalance in stroke severity. Limited data showed no difference between the treatment and control groups for functional outcome, dependence or proportion of patients dead or dependent. Adverse effects were not reported. There is some suggestion (but no statistically significant result) of an unfavourable effect of piracetam on early death, but this may have been caused by baseline differences in stroke severity in the trials. There is not enough evidence to assess the effect of piracetam on dependence.

  13. Stroke survivors' endorsement of a "stress belief model" of stroke prevention predicts control of risk factors for recurrent stroke.

    Science.gov (United States)

    Phillips, L Alison; Tuhrim, Stanley; Kronish, Ian M; Horowitz, Carol R

    2014-01-01

    Perceptions that stress causes and stress-reduction controls hypertension have been associated with poorer blood pressure (BP) control in hypertension populations. The current study investigated these "stress-model perceptions" in stroke survivors regarding prevention of recurrent stroke and the influence of these perceptions on patients' stroke risk factor control. Stroke and transient ischemic attack survivors (N=600) participated in an in-person interview in which they were asked about their beliefs regarding control of future stroke; BP and cholesterol were measured directly after the interview. Counter to expectations, patients who endorsed a "stress-model" but not a "medication-model" of stroke prevention were in better control of their stroke risk factors (BP and cholesterol) than those who endorsed a medication-model but not a stress-model of stroke prevention (OR for poor control=.54, Wald statistic=6.07, p=.01). This result was not explained by between group differences in patients' reported medication adherence. The results have implications for theory and practice, regarding the role of stress belief models and acute cardiac events, compared to chronic hypertension.

  14. Leukocytosis in acute stroke

    DEFF Research Database (Denmark)

    Kammersgaard, L P; Jørgensen, H S; Nakayama, H

    1999-01-01

    Leukocytosis is a common finding in the acute phase of stroke. A detrimental effect of leukocytosis on stroke outcome has been suggested, and trials aiming at reducing the leukocyte response in acute stroke are currently being conducted. However, the influence of leukocytosis on stroke outcome has...

  15. Stroke: First Aid

    Science.gov (United States)

    First aid Stroke: First aid Stroke: First aid By Mayo Clinic Staff A stroke occurs when there's bleeding into your brain or when blood flow to your ... cells start dying. Seek immediate medical assistance. A stroke is a true emergency. The sooner treatment is ...

  16. Lacunar strokes: a single institutional experience

    Directory of Open Access Journals (Sweden)

    Osama Shukir Muhammed Amin

    2013-08-01

    Full Text Available Abstract: Objective: Lacunar ischemic strokes comprise approximately 25% of all ischemic strokes. We compared the risk factors and clinical pattern of this type of stroke between males and females. Methods: This observational study involved 50 consecutive patients with their first-ever lacunar stroke and was conducted at the department of neurology of Sulaimaniya general teaching hospital, Iraq from December 1, 2010 to March 1, 2013. Patients’ risk factors, clinical presentation, and strokes’ patterns were noted and a comparison was made between males and females. Results: Males (64% outnumbered females (36% with a male to female ration of 1.7. The mean age of males was 63 years while it was 61 years in females. Although hypertension was more common in females than in males, diabetes and smoking were more common in the latter group; however, there were no statistically significant differences between the 2 genders in terms of hypertension (P-value <0.3 and diabetes (P-value < 0.07 while smoking was strongly associated with male gender (P-value<0.0001. Pure motor hemiparesis, ataxic hemiparesis, pure sensory stroke, and dysarthria-clumsy hand syndrome were more common in males; only senori-motor stroke revealed a statistically significant difference in favor males (P-value<0.0001; 95% CI -1.7 to 19.2. There was no statistically significant difference in terms of which side of the brain was infarcted between males and females (P-value<0.4. Conclusion: Males around the age of 63 years were the main target for these lacunar strokes. Cigarette smoking and sensorimotor strokes were significantly associated with male gender. [Cukurova Med J 2013; 38(4.000: 659-666

  17. Adapting the Home After a Stroke

    Science.gov (United States)

    ... News About Neurology Image Library Search The Internet Stroke Center Patients & Families About Stroke Stroke Diagnosis Stroke ... after a Stroke Adapting the Home after a Stroke Caregiver Introduction What is Aphasia? Stroke Recovery Guides ...

  18. Cosmic Statistics of Statistics

    OpenAIRE

    Szapudi, I.; Colombi, S.; Bernardeau, F.

    1999-01-01

    The errors on statistics measured in finite galaxy catalogs are exhaustively investigated. The theory of errors on factorial moments by Szapudi & Colombi (1996) is applied to cumulants via a series expansion method. All results are subsequently extended to the weakly non-linear regime. Together with previous investigations this yields an analytic theory of the errors for moments and connected moments of counts in cells from highly nonlinear to weakly nonlinear scales. The final analytic formu...

  19. Ecotoxicology is not normal: A comparison of statistical approaches for analysis of count and proportion data in ecotoxicology.

    Science.gov (United States)

    Szöcs, Eduard; Schäfer, Ralf B

    2015-09-01

    Ecotoxicologists often encounter count and proportion data that are rarely normally distributed. To meet the assumptions of the linear model, such data are usually transformed or non-parametric methods are used if the transformed data still violate the assumptions. Generalized linear models (GLMs) allow to directly model such data, without the need for transformation. Here, we compare the performance of two parametric methods, i.e., (1) the linear model (assuming normality of transformed data), (2) GLMs (assuming a Poisson, negative binomial, or binomially distributed response), and (3) non-parametric methods. We simulated typical data mimicking low replicated ecotoxicological experiments of two common data types (counts and proportions from counts). We compared the performance of the different methods in terms of statistical power and Type I error for detecting a general treatment effect and determining the lowest observed effect concentration (LOEC). In addition, we outlined differences on a real-world mesocosm data set. For count data, we found that the quasi-Poisson model yielded the highest power. The negative binomial GLM resulted in increased Type I errors, which could be fixed using the parametric bootstrap. For proportions, binomial GLMs performed better than the linear model, except to determine LOEC at extremely low sample sizes. The compared non-parametric methods had generally lower power. We recommend that counts in one-factorial experiments should be analyzed using quasi-Poisson models and proportions from counts by binomial GLMs. These methods should become standard in ecotoxicology.

  20. Injury Statistics

    Science.gov (United States)

    ... Certification Import Surveillance International Recall Guidance Civil and Criminal Penalties Federal Court Orders & Decisions Research & Statistics Research & Statistics Technical Reports Injury Statistics NEISS ...

  1. Stroke Location Is an Independent Predictor of Cognitive Outcome.

    Science.gov (United States)

    Munsch, Fanny; Sagnier, Sharmila; Asselineau, Julien; Bigourdan, Antoine; Guttmann, Charles R; Debruxelles, Sabrina; Poli, Mathilde; Renou, Pauline; Perez, Paul; Dousset, Vincent; Sibon, Igor; Tourdias, Thomas

    2016-01-01

    On top of functional outcome, accurate prediction of cognitive outcome for stroke patients is an unmet need with major implications for clinical management. We investigated whether stroke location may contribute independent prognostic value to multifactorial predictive models of functional and cognitive outcomes. Four hundred twenty-eight consecutive patients with ischemic stroke were prospectively assessed with magnetic resonance imaging at 24 to 72 hours and at 3 months for functional outcome using the modified Rankin Scale and cognitive outcome using the Montreal Cognitive Assessment (MoCA). Statistical maps of functional and cognitive eloquent regions were derived from the first 215 patients (development sample) using voxel-based lesion-symptom mapping. We used multivariate logistic regression models to study the influence of stroke location (number of eloquent voxels from voxel-based lesion-symptom mapping maps), age, initial National Institutes of Health Stroke Scale and stroke volume on modified Rankin Scale and MoCA. The second part of our cohort was used as an independent replication sample. In univariate analyses, stroke location, age, initial National Institutes of Health Stroke Scale, and stroke volume were all predictive of poor modified Rankin Scale and MoCA. In multivariable analyses, stroke location remained the strongest independent predictor of MoCA and significantly improved the prediction compared with using only age, initial National Institutes of Health Stroke Scale, and stroke volume (area under the curve increased from 0.697-0.771; difference=0.073; 95% confidence interval, 0.008-0.155). In contrast, stroke location did not persist as independent predictor of modified Rankin Scale that was mainly driven by initial National Institutes of Health Stroke Scale (area under the curve going from 0.840 to 0.835). Similar results were obtained in the replication sample. Stroke location is an independent predictor of cognitive outcome (MoCA) at 3

  2. Nonparametric Statistical Structuring of Knowledge Systems Using Binary Feature Matches

    DEFF Research Database (Denmark)

    Mørup, Morten; Kano Glückstad, Fumiko; Herlau, Tue

    2014-01-01

    Structuring knowledge systems with binary features is often based on imposing a similarity measure and clustering objects according to this similarity. Unfortunately, such analyses can be heavily influenced by the choice of similarity measure. Furthermore, it is unclear at which level clusters have...... statistical support and how this approach generalizes to the structuring and alignment of knowledge systems. We propose a non-parametric Bayesian generative model for structuring binary feature data that does not depend on a specific choice of similarity measure. We jointly model all combinations of binary...... matches and structure the data into groups at the level in which they have statistical support. The model naturally extends to structuring and aligning an arbitrary number of systems. We analyze three datasets on educational concepts and their features and demonstrate how the proposed model can both...

  3. Nonparametric statistical structuring of knowledge systems using binary feature matches

    DEFF Research Database (Denmark)

    Mørup, Morten; Glückstad, Fumiko Kano; Herlau, Tue

    2014-01-01

    Structuring knowledge systems with binary features is often based on imposing a similarity measure and clustering objects according to this similarity. Unfortunately, such analyses can be heavily influenced by the choice of similarity measure. Furthermore, it is unclear at which level clusters have...... statistical support and how this approach generalizes to the structuring and alignment of knowledge systems. We propose a non-parametric Bayesian generative model for structuring binary feature data that does not depend on a specific choice of similarity measure. We jointly model all combinations of binary...... matches and structure the data into groups at the level in which they have statistical support. The model naturally extends to structuring and aligning an arbitrary number of systems. We analyze three datasets on educational concepts and their features and demonstrate how the proposed model can both...

  4. Airplane stroke syndrome.

    Science.gov (United States)

    Humaidan, Hani; Yassi, Nawaf; Weir, Louise; Davis, Stephen M; Meretoja, Atte

    2016-07-01

    Only 37 cases of stroke during or soon after long-haul flights have been published to our knowledge. In this retrospective observational study, we searched the Royal Melbourne Hospital prospective stroke database and all discharge summaries from 1 September 2003 to 30 September 2014 for flight-related strokes, defined as patients presenting with stroke within 14days of air travel. We hypothesised that a patent foramen ovale (PFO) is an important, but not the only mechanism, of flight-related stroke. We describe the patient, stroke, and flight characteristics. Over the study period, 131 million passengers arrived at Melbourne airport. Our centre admitted 5727 stroke patients, of whom 42 (0.73%) had flight-related strokes. Flight-related stroke patients were younger (median age 65 versus 73, p<0.001), had similar stroke severity, and received intravenous thrombolysis more often than non-flight-related stroke patients. Seven patients had flight-related intracerebral haemorrhage. The aetiology of the ischaemic strokes was cardioembolic in 14/35 (40%), including seven patients with confirmed PFO, one with atrial septal defect, four with atrial fibrillation, one with endocarditis, and one with aortic arch atheroma. Paradoxical embolism was confirmed in six patients. Stroke related to air travel is a rare occurrence, less than one in a million. Although 20% of patients had a PFO, distribution of stroke aetiologies was diverse and was not limited to PFO and paradoxical embolism. Copyright © 2016 Elsevier Ltd. All rights reserved.

  5. Statistical thermodynamics

    International Nuclear Information System (INIS)

    Lim, Gyeong Hui

    2008-03-01

    This book consists of 15 chapters, which are basic conception and meaning of statistical thermodynamics, Maxwell-Boltzmann's statistics, ensemble, thermodynamics function and fluctuation, statistical dynamics with independent particle system, ideal molecular system, chemical equilibrium and chemical reaction rate in ideal gas mixture, classical statistical thermodynamics, ideal lattice model, lattice statistics and nonideal lattice model, imperfect gas theory on liquid, theory on solution, statistical thermodynamics of interface, statistical thermodynamics of a high molecule system and quantum statistics

  6. Incidence and types of sleep disorders in patients with stroke.

    Science.gov (United States)

    Pasic, Zejneba; Smajlovic, Dzevdet; Dostovic, Zikrija; Kojic, Biljana; Selmanovic, Senada

    2011-01-01

    Sleep disorders (SD) after stroke (stroke) are common occurrences, and most often in sleep apnea, insomnia and daytime sleepiness. GOALS. Research goals were to determine the types of SD and their frequency in patients with stroke in relation to the type of stroke and side of lesion. The study analyzed 200 patients with acute stroke hospitalized in the Clinic of Neurology, University Clinical Centre Tuzla in the period from 1st August 2007 to 1st June 2008. All patients have confirmed the existence of stroke by computerized tomography. SD was verified according to the General Curriculum of sleep, the Berlin questionnaire and Epvort scale. Stroke, by type, were divided into hemorrhagic and ischemic, and the localization of the stroke to right and left cerebral hemispheres. Of the total number of respondents, 78% had SD. Very serious level of SD had 42% of respondents, 20% moderate, and 16% of medium-severe degree. There was no statistically significant differences in the frequency of SD among patients with ischemic and hemorrhagic stroke (76.8%: 82.5%, p = 0.58). In relation to the side of lesion there was more patient with SD and stroke in the right cerebral hemisphere, but there were no statistically significant differences (39.5%: 33%, p = 0.1). According Epvort scale sleep apnea and snoring was present in 86%, daytime sleepiness in 49.5% and narcolepsy 0.5%. Sleep disturbance as a neuropsychological disorder has a significant incidence in the acute phase of stroke. SD is slightly more common in hemorrhagic stroke and stroke in the right hemisphere. Sleep Apnea and snoring are the most common types of SD in patients with stroke.

  7. Cancer in young adults with ischemic stroke.

    Science.gov (United States)

    Aarnio, Karoliina; Joensuu, Heikki; Haapaniemi, Elena; Melkas, Susanna; Kaste, Markku; Tatlisumak, Turgut; Putaala, Jukka

    2015-06-01

    Cancer is a risk factor for ischemic stroke. Little is known about cancer among young adults with ischemic stroke. We studied the frequency of cancer and its association with long-term risk of death among young patients with first-ever ischemic stroke. 1002 patients aged 15 to 49 years, registered in the Helsinki Young Stroke Registry, and with a median follow-up of 10.0 years (interquartile range 6.5-13.8) after stroke were included. Historical and follow-up data were derived from the Finnish Care Register and Statistics Finland. Survival between groups was compared with the Kaplan-Meier life-table method, and Cox proportional hazard models were used to identify factors associated with mortality. One or more cancer diagnosis was made in 77 (7.7%) patients, of whom 39 (3.9%) had cancer diagnosed prestroke. During the poststroke follow-up, 41 (53.2%) of the cancer patients died. Median time from prestroke cancer to stroke was 4.9 (1.0-9.5) years and from stroke to poststroke cancer was 6.7 (2.7-10.9) years. Poststroke cancer was associated with age>40 years, heavy drinking, and cigarette smoking. The cumulative mortality was significantly higher among the cancer patients (68.6%, 95% confidence interval 52.0%-85.3%) compared with patients without cancer (19.7%, 95% confidence interval 16.3%-23.2%). Active cancer at index stroke, melanoma, and lung/respiratory tract cancer had the strongest independent association with death during the follow-up when adjusted for known poststroke mortality prognosticators. Cancer, and especially active cancer and no other apparent cause for stroke, is associated with unfavorable survival among young stroke patients. © 2015 American Heart Association, Inc.

  8. Risks for Heart Disease & Stroke

    Science.gov (United States)

    ... Risks for Heart Disease & Stroke Risks for Heart Disease & Stroke About 1.5 million heart attacks and strokes ... the Centers for Disease Control and Prevention: Heart Disease Stroke High Blood Pressure Cholesterol Salt Video: Know Your ...

  9. The analysis of variance in anaesthetic research: statistics, biography and history.

    Science.gov (United States)

    Pandit, J J

    2010-12-01

    Multiple t-tests (or their non-parametric equivalents) are often used erroneously to compare the means of three or more groups in anaesthetic research. Methods for correcting the p value regarded as significant can be applied to take account of multiple testing, but these are somewhat arbitrary and do not avoid several unwieldy calculations. The appropriate method for most such comparisons is the 'analysis of variance' that not only economises on the number of statistical procedures, but also indicates if underlying factors or sub-groups have contributed to any significant results. This article outlines the history, rationale and method of this analysis.

  10. Statistical significance of trends in monthly heavy precipitation over the US

    KAUST Repository

    Mahajan, Salil

    2011-05-11

    Trends in monthly heavy precipitation, defined by a return period of one year, are assessed for statistical significance in observations and Global Climate Model (GCM) simulations over the contiguous United States using Monte Carlo non-parametric and parametric bootstrapping techniques. The results from the two Monte Carlo approaches are found to be similar to each other, and also to the traditional non-parametric Kendall\\'s τ test, implying the robustness of the approach. Two different observational data-sets are employed to test for trends in monthly heavy precipitation and are found to exhibit consistent results. Both data-sets demonstrate upward trends, one of which is found to be statistically significant at the 95% confidence level. Upward trends similar to observations are observed in some climate model simulations of the twentieth century, but their statistical significance is marginal. For projections of the twenty-first century, a statistically significant upwards trend is observed in most of the climate models analyzed. The change in the simulated precipitation variance appears to be more important in the twenty-first century projections than changes in the mean precipitation. Stochastic fluctuations of the climate-system are found to be dominate monthly heavy precipitation as some GCM simulations show a downwards trend even in the twenty-first century projections when the greenhouse gas forcings are strong. © 2011 Springer-Verlag.

  11. MEAN PLATELET VOLUME AND RISK OF THROMBOTIC STROKE

    Directory of Open Access Journals (Sweden)

    Prasantha Kumar Thankappan

    2017-07-01

    Full Text Available BACKGROUND Stroke is a major cause of long term morbidity and mortality. Several factors are known to increase the liability to stroke. Platelets play a crucial role in the pathogenesis of atherosclerotic complications, contributing to thrombus formation. Platelet size (mean platelet volume, MPV is a marker and possible determinant of platelet function, large platelets being potentially more reactive. Hence an attempt has-been made to study the association if any between mean platelet volume and thrombotic stroke. The aim of this study was to determine whether an association exists between Mean Platelet Volume (MPV and thrombotic stroke. MATERIALS AND METHODS The study is a case control study and data was collected at Government Medical College Hospital, Kottayam, Kerala a tertiary care referral centre. The study was carried out among fifty patients diagnosed with thrombotic stroke and presenting to the hospital within forty eight hours of onset of symptoms. Fifty age group and sex matched controls were also recruited. Mean platelet volume was obtained using a SYSMEX automated analyser. RESULTS This study has shown a statistically significant relation between mean platelet volume and risk of thrombotic stroke but no statistically significant correlation between clinical severity of stroke and mean platelet volume. CONCLUSION This study has shown an elevation of MPV in acute phase of thrombotic stroke. Platelet mass was found to be more or less a constant. This study did not find a statistically significant correlation between clinical severity of stroke and mean platelet volume.

  12. Post-stroke depression: Prevalence and relationship with disability in chronic stroke survivors

    Directory of Open Access Journals (Sweden)

    Srivastava Abhishek

    2010-01-01

    Full Text Available Objectives: To evaluate (1 the prevalence of operationally defined depressive disorder (ICD-10 in chronic stroke subjects and (2 the relationship of post-stroke depression (PSD with disability. Design: Cross-sectional, descriptive study. Setting: Neurological rehabilitation unit of a tertiary care university research center. Materials and Methods: Participants were those with first episode of supratentorial stroke of more than 3 months′ duration with impaired balance and gait who had been referred for rehabilitation. Data were collected on demographic data, stroke data (side and type of lesion and post-stroke duration, cognition (mini mental state examination, depressive ideation (Hamilton Depression Rating Scale - HRDS, impairment (Scandinavian Stroke Scale, balance (Berg Balance Scale, ambulatory status (Functional Ambulation Category, walking ability (speed, and independence in activities of daily living (Barthel Index. Statistical analysis was done using SPSS 13.0. We carried out the chi-square test for ordinal variables and the independent t test for continuous variables. Results: Fifty-one patients (M:F: 41:10 of mean age 46.06 ± 11.19 years and mean post-stroke duration of 467.33 ± 436.39 days were included in the study. Eighteen of the 51 participants (35.29% met the criteria for depression. Demographic variables like male gender, being married, living in a nuclear family, urban background, and higher HRDS score were significantly correlated with PSD (P < 0.05. Depression was related to functional disability after stroke but to a statistically insignificant level (P > 0.05 and was unrelated to lesion-related parameters. Conclusion: Depression occurs in one-third of chronic stroke survivors and is prevalent in subjects referred for rehabilitation. PSD is related primarily to demographic variables and only to a lesser extent to functional disability following stroke.

  13. Test Your Stroke Knowledge

    Science.gov (United States)

    ... 9-1-1. Which of the following are risk factors for stroke? High blood pressure Heart disease Smoking High cholesterol Diabetes Show Answer All of these are risk factors for stroke. If you smoke - quit. If you have high ...

  14. Heart and Stroke Encyclopedia

    Science.gov (United States)

    ... Thromboembolism Aortic Aneurysm More The Heart and Stroke Encyclopedia Click a letter below to get a brief ... of cardiovascular terms from our Heart and Stroke Encyclopedia and get links to in-depth information. A ...

  15. Stroke Connection Magazine

    Science.gov (United States)

    ... Resources Submit A Story Edit Module Show Tags Stroke Rehabilitation Two-Part Series Making the Best Decisions at ... first part of a two-part series on stroke rehab, we offer guidance for the decision-making process ...

  16. Stroke (For Kids)

    Science.gov (United States)

    ... your friend. Being around friends can help with healing. Preventing Strokes Some strokes can be prevented in ... Why Does Hair Turn Gray? What Are Wrinkles? Alzheimer Disease Your Brain & Nervous System Why Exercise Is ...

  17. Stroke Trials Registry

    Science.gov (United States)

    ... News About Neurology Image Library Search The Internet Stroke Center Trials Registry Clinical Trials Interventions Conditions Sponsors ... a clinical trial near you Welcome to the Stroke Trials Registry Our registry of clinical trials in ...

  18. Choosing the best non-parametric richness estimator for benthic macroinvertebrates databases Eligiendo el mejor estimador no paramétrico para calcular riqueza en bases de datos de macroinvertebrados bentónicos

    Directory of Open Access Journals (Sweden)

    Carola V. Basualdo

    2011-06-01

    Full Text Available Non-parametric estimators allow to compare the estimates of richness among data sets from heterogeneous sources. However, since the estimator performance depends on the species-abundance distribution of the sample, preference for one or another is a difficult issue. The present study recovers and revalues some criteria already present in the literature in order to choose the most suitable estimator for streams macroinvertebrates, and provides some tools to apply them. Two abundance and four incidence estimators were applied to a regional database at family and genus level. They were evaluated under four criteria: sub-sample size required to estimate the observed richness; constancy of the sub-sample size; lack of erratic behavior and similarity in curve shape through different data sets. Among incidence estimators, Jack1 had the best performance. Between abundance estimators, ACE was the best when the observed richness was small and Chao1 when the observed richness was high. The uniformity of curves shapes allowed to describe the general sequences of curves behavior that could act as references to compare estimations of small databases and to infer the possible behavior of the curve (i.e the expected richness if the sample were larger. These results can be very useful for environmental management, and update the state of knowledge of regional macroinvertebrates.Los estimadores no paramétricos permiten comparar la riqueza estimada de conjuntos de datos de origen diverso. Empero, como su comportamiento depende de la distribución de abundancia del conjunto de datos, la preferencia por alguno representa una decisión difícil. Este trabajo rescata algunos criterios presentes en la literatura para elegir el estimador más adecuado para macroinvertebrados bentónicos de ríos y ofrece algunas herramientas para su aplicación. Cuatro estimadores de incidencia y dos de abundancia se aplicaron a un inventario regional a nivel de familia y género. Para

  19. [Genetics of ischemic stroke].

    Science.gov (United States)

    Gschwendtner, A; Dichgans, M

    2013-02-01

    Stroke is one of the most widespread causes of mortality und disability worldwide. Around 80 % of strokes are ischemic and different forms of intracranial bleeding account for the remaining cases. Monogenic stroke disorders are rare but the diagnosis may lead to specific therapeutic consequences for the affected patients who are predominantly young. In common sporadic stroke, genetic factors play a role in the form of susceptibility genes. Their discovery may give rise to new therapeutic options in the future.

  20. Hemorrhagic Stroke in Children

    OpenAIRE

    Jordan M.D., Lori C.; Hillis M.D., Argye E.

    2007-01-01

    Hemorrhagic stroke accounts for approximately half of stroke in childhood. Unlike arterial ischemic stroke, there are no consensus guidelines to assist in the evaluation and treatment of these children. We review the literature on the evaluation, treatment, etiology and neurologic outcome of hemorrhagic stroke in children. Important differences between pediatric and adult hemorrhage are highlighted, as treatment guidelines for adults may not be applicable in all cases. Needed future research ...

  1. Suicide after a stroke: a population study

    DEFF Research Database (Denmark)

    Teasdale, T W; Engberg, A W

    2001-01-01

    STUDY OBJECTIVE: To establish whether there are increased rates of suicide after a stroke and the degree to which any increase is related to gender, age at stroke, diagnosis, duration of hospitalisation, and time since stroke. DESIGN: Cross linkage of national registers for hospitalisations...... cases of suicide were identified. MAIN RESULTS: Annual incidence rates, both observed and expected, together with standardised mortality ratios (SMR) were computed based on annual population and suicide statistics, stratified by age and gender. The overall annual incidence rate of suicide in the cohort.......76) for patients under 50 years of age group and were least for patients 80 years or older (1.3; 0.95, 1.79). There was no clear relation to stroke diagnosis. Suicides were negatively related to duration of hospitalisation, being lowest for those hospitalised for more than three months (0.88; 0.65, 1...

  2. Measurement of vertical stroke Vub vertical stroke using b hadron semileptonic decay

    International Nuclear Information System (INIS)

    Abbiendi, G.; Aakesson, P.F.

    2001-01-01

    The magnitude of the CKM matrix element vertical stroke V ub vertical stroke is determined by measuring the inclusive charmless semileptonic branching fraction of beauty hadrons at OPAL based on b → X u lν event topology and kinematics. This analysis uses OPAL data collected between 1991 and 1995, which correspond to about four million hadronic Z decays. We measure Br(b → X u lν) to be (1.63 ±0.53 +0.55 -0.62 ) x 10 -3 . The first uncertainty is the statistical error and the second is the systematic error. From this analysis, vertical stroke V ub vertical stroke is determined to be: vertical stroke V ub vertical stroke =(4.00±0.65(stat) +0.67 -0.76 (sys)±0.19(HQE)) x 10 -3 . The last error represents the theoretical uncertainties related to the extraction of vertical stroke V ub vertical stroke from Br(b→X u l ν) using the Heavy Quark Expansion. (orig.)

  3. Cancer Statistics

    Science.gov (United States)

    ... What Is Cancer? Cancer Statistics Cancer Disparities Cancer Statistics Cancer has a major impact on society in ... success of efforts to control and manage cancer. Statistics at a Glance: The Burden of Cancer in ...

  4. Caregiving Statistics

    Science.gov (United States)

    ... Coping with Alzheimer’s COPD Caregiving Take Care! Caregiver Statistics Statistics on Family Caregivers and Family Caregiving Caregiving Population ... Health Care Caregiver Self-Awareness State by State Statistics Caregiving Population The value of the services family ...

  5. Recurrent Stroke: The Value of the CHA2DS2VASc Score and the Essen Stroke Risk Score in a Nationwide Stroke Cohort.

    Science.gov (United States)

    Andersen, Søren Due; Gorst-Rasmussen, Anders; Lip, Gregory Y H; Bach, Flemming W; Larsen, Torben Bjerregaard

    2015-09-01

    The CHA2DS2VASc score and the Essen Stroke Risk Score are respectively used for risk stratification in patients with atrial fibrillation and in patients with cerebrovascular incidents. We aimed to test the ability of the 2 scores to predict stroke recurrence, death, and cardiovascular events (stroke, transient ischemic attack, myocardial infarction, or arterial thromboembolism) in a nationwide Danish cohort study, among patients with incident ischemic stroke and no atrial fibrillation. We conducted a registry-based study in patients with incident ischemic stroke and no atrial fibrillation. Patients were stratified according to the CHA2DS2VASc score and the Essen Stroke Risk Score and were followed up until stroke recurrence or death. We estimated stratified incidence rates and hazard ratios and calculated the cumulative risks. 42 182 patients with incident ischemic stroke with median age 70.1 years were included. The overall 1-year incidence rates of recurrent stroke, death, and cardiovascular events were 3.6%, 10.5%, and 6.7%, respectively. The incidence rates, the hazard ratios, and the cumulative risk of all outcomes increased with increasing risk scores. C-statistics for both risk scores were around 0.55 for 1-year stroke recurrence and cardiovascular events and correspondingly for death around 0.67 for both scores. In this cohort of non-atrial fibrillation patients with incident ischemic stroke, increasing CHA2DS2VASc score and Essen Stroke Risk Score was associated with increasing risk of recurrent stroke, death, and cardiovascular events. Their discriminatory performance was modest and further refinements are required for clinical application. © 2015 American Heart Association, Inc.

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

    Directory of Open Access Journals (Sweden)

    Annie Chu

    2009-04-01

    Full Text Available 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.

  7. The Christchurch earthquake stroke incidence study.

    Science.gov (United States)

    Wu, Teddy Y; Cheung, Jeanette; Cole, David; Fink, John N

    2014-03-01

    We examined the impact of major earthquakes on acute stroke admissions by a retrospective review of stroke admissions in the 6 weeks following the 4 September 2010 and 22 February 2011 earthquakes. The control period was the corresponding 6 weeks in the previous year. In the 6 weeks following the September 2010 earthquake there were 97 acute stroke admissions, with 79 (81.4%) ischaemic infarctions. This was similar to the 2009 control period which had 104 acute stroke admissions, of whom 80 (76.9%) had ischaemic infarction. In the 6 weeks following the February 2011 earthquake, there were 71 stroke admissions, and 61 (79.2%) were ischaemic infarction. This was less than the 96 strokes (72 [75%] ischaemic infarction) in the corresponding control period. None of the comparisons were statistically significant. There was also no difference in the rate of cardioembolic infarction from atrial fibrillation between the study periods. Patients admitted during the February 2011 earthquake period were less likely to be discharged directly home when compared to the control period (31.2% versus 46.9%, p=0.036). There was no observable trend in the number of weekly stroke admissions between the 2 weeks leading to and 6 weeks following the earthquakes. Our results suggest that severe psychological stress from earthquakes did not influence the subsequent short term risk of acute stroke, but the severity of the earthquake in February 2011 and associated civil structural damages may have influenced the pattern of discharge for stroke patients. Copyright © 2013 Elsevier Ltd. All rights reserved.

  8. Sex Disparities in Stroke

    DEFF Research Database (Denmark)

    Dehlendorff, Christian; Andersen, Klaus Kaae; Olsen, Tom Skyhøj

    2015-01-01

    between 2003 and 2012 (N=79 617), and the Danish Register of Causes of Death. Information was available on age, sex, marital status, stroke severity, stroke subtype, socioeconomic status, and cardiovascular risk profile. We studied only deaths due to the index stroke, with the assumption that death.......5%) or 1 month (6.9%), respectively. After the age of 60 years, women had more severe strokes than men. Up to ages in the mid-60s, no difference in the risk of death from stroke was seen between the 2 sexes. For people aged >65 years, however, the risk gradually became greater in men than in women...

  9. Voxel-based lesion-symptom mapping of stroke lesions underlying somatosensory deficits

    Science.gov (United States)

    Meyer, Sarah; Kessner, Simon S.; Cheng, Bastian; Bönstrup, Marlene; Schulz, Robert; Hummel, Friedhelm C.; De Bruyn, Nele; Peeters, Andre; Van Pesch, Vincent; Duprez, Thierry; Sunaert, Stefan; Schrooten, Maarten; Feys, Hilde; Gerloff, Christian; Thomalla, Götz; Thijs, Vincent; Verheyden, Geert

    2015-01-01

    The aim of this study was to investigate the relationship between stroke lesion location and the resulting somatosensory deficit. We studied exteroceptive and proprioceptive somatosensory symptoms and stroke lesions in 38 patients with first-ever acute stroke. The Erasmus modified Nottingham Sensory Assessment was used to clinically evaluate somatosensory functioning in the arm and hand within the first week after stroke onset. Additionally, more objective measures such as the perceptual threshold of touch and somatosensory evoked potentials were recorded. Non-parametric voxel-based lesion-symptom mapping was performed to investigate lesion contribution to different somatosensory deficits in the upper limb. Additionally, structural connectivity of brain areas that demonstrated the strongest association with somatosensory symptoms was determined, using probabilistic fiber tracking based on diffusion tensor imaging data from a healthy age-matched sample. Voxels with a significant association to somatosensory deficits were clustered in two core brain regions: the central parietal white matter, also referred to as the sensory component of the superior thalamic radiation, and the parietal operculum close to the insular cortex, representing the secondary somatosensory cortex. Our objective recordings confirmed findings from clinical assessments. Probabilistic tracking connected the first region to thalamus, internal capsule, brain stem, postcentral gyrus, cerebellum, and frontal pathways, while the second region demonstrated structural connections to thalamus, insular and primary somatosensory cortex. This study reveals that stroke lesions in the sensory fibers of the superior thalamocortical radiation and the parietal operculum are significantly associated with multiple exteroceptive and proprioceptive deficits in the arm and hand. PMID:26900565

  10. Pregnancy and puerperium-related strokes in Asian women.

    Science.gov (United States)

    Khan, Maria; Wasay, Mohammad; Menon, Bindu; Saadatnia, Mohammad; Venketasubramanian, Narayanaswamy; Gunaratne, Padma; Mehndiratta, M M; Dai, Alper; Kaul, Subhash

    2013-11-01

    Despite an increased risk of stroke in pregnancy and puerperium, the overall incidence of the condition in this population is low. Therefore, there is limited data pertaining to these patients particularly from Asian countries. Our objective was to describe the risk factors and outcomes of 110 pregnancy-related ischemic strokes from 5 Asian countries. Data were collected by retrospective chart review in most cases and prospectively in the rest. Inclusion criteria for this subanalysis were women, pregnant or within 1-month postpartum, presenting to the study center with acute ischemic stroke (arterial or venous) confirmed by neuroimaging. Intracranial hemorrhages other than the ones associated with cerebral venous thrombosis or hemorrhagic infarct were excluded. Risk factors were diagnosed based on already published criteria. Outcomes were measured using modified Rankin score. Statistical analysis was done using Statistical Package for Social Sciences version 19.0. In all, 110 women with mean age of 27.94 years presented with pregnancy-related ischemic strokes; 58.2% of the strokes occurred postpartum and 49.1% were secondary to cerebral venous thrombosis. Venous strokes were significantly more likely to occur postpartum compared with arterial strokes (P=.01), to have abnormal "hypercoagulable panel result on admission" (PAsian women. Both traditional and pregnancy-specific risk factors should be addressed to control ischemic stroke risk in these women. Copyright © 2013 National Stroke Association. Published by Elsevier Inc. All rights reserved.

  11. Personality as significant predictor of post-stroke anxiety.

    Science.gov (United States)

    Solgajová, Andrea; Sollár, Tomáš; Vörösová, Gabriela; Zrubcová, Dana

    2017-08-01

    Anxiety in stroke patients is very frequent. It negatively influences the whole recovery process. The study objective is to study personality traits, age, gender, and type of stroke as predictors of anxiety in stroke patients. Research presents a prospective cross-sectional descriptive study. The sample consisted of 74 hospitalized stroke patients. The data collection methods were the HADS for anxiety measurement and the Mini IPIP for evaluation of five personality factors. Hierarchical multiple regression analysis was used to study the relationship between anxiety and personality variables, gender, age, and type of stroke. We found three statistically significant predictors of anxiety in stroke patients. Neuroticism and low Agreeableness explain 50% of the variability of anxiety. Another statistically significant predictor was age; higher-level anxiety relates to lower age. Other personality traits (Extraversion, Openness to experience, and Conscientiousness), gender, and type of stroke do not appear as significant predictors of post-stroke anxiety. Anxiety in stroke patients is predicted mostly by the personality traits and young age of patients. Knowing these predictors can result in early detection and management of emotional consequences of disease, and thus influence the whole recovery process.

  12. Clinical Epidemiology Of Stroke

    Directory of Open Access Journals (Sweden)

    Nagaraja D

    2005-01-01

    Full Text Available Stroke is a huge public health problem because of its high morbidity and disability. The epidemiology of stroke is of relevance to construct practical paradigms to tackle this major health issue in the community. Recent data have shown that about 72-86% of strokes are ischemic, 9-18% are due to hemorrhage (intracerebral of subarachnoid and the rest are undefined. The risk factors for stroke are multiple and combined. At present, stroke is no more considered as unavoidable and untreatable. It is an emergency and specialized units and teams improve outcome and lower costs. Death related to stroke is declining in many countries and in both sexes. This decrease in multifactorial. The detection and more effective treatment of hypertension may play an important factor, as well as the improved medical care and improvement in diagnostic procedures. While stroke incidence appears stable and stroke mortality is slowly declining, the absolute magnitude of stroke is likely to grow over the next 30 years. as the population ages, the absolute number of stroke victims and demands on healthcare and other support systems is likely to increase substantially in the future. Keeping this in perspective, this chapter shall focus on the epidemiology of stroke in the world and in Indian, in particular.

  13. Registration of acute stroke

    DEFF Research Database (Denmark)

    Wildenschild, Cathrine; Mehnert, Frank; Thomsen, Reimar Wernich

    2014-01-01

    BACKGROUND: The validity of the registration of patients in stroke-specific registries has seldom been investigated, nor compared with administrative hospital discharge registries. The objective of this study was to examine the validity of the registration of patients in a stroke-specific registry...... (The Danish Stroke Registry [DSR]) and a hospital discharge registry (The Danish National Patient Registry [DNRP]). METHODS: Assuming that all patients with stroke were registered in either the DSR, DNRP or both, we first identified a sample of 75 patients registered with stroke in 2009; 25 patients...... in the DSR, 25 patients in the DNRP, and 25 patients registered in both data sources. Using the medical record as a gold standard, we then estimated the sensitivity and positive predictive value of a stroke diagnosis in the DSR and the DNRP. Secondly, we reviewed 160 medical records for all potential stroke...

  14. Sleep and Stroke

    Directory of Open Access Journals (Sweden)

    M V Padma Srivastav

    2014-03-01

    Full Text Available Circadian variations in conjunction with sleep-related heart rhythm changes and sleepdisordered breathing (SDB are contributing risk factors for stroke. Strong scientificevidence now exists indicating that SDB contributes to systemic hypertension, aprominent risk factor for stroke, and compelling circumstantial evidence is presentsuggesting that SDB raises the risk for development of stroke through other circulatorymechanisms as well. Preliminary evidence indicates that post-stroke patients have ahigher prevalence of SDB, which is likely to compromise their rehabilitation outcomes.Since SDB is modifiable with the application of CPAP and other treatment modalities,there is practical value in investigating patients at risk of stroke or post stroke forpresence of SDB. Successful application of CPAP or BiPAP therapy may improve theoutcome in both instances.Key words : Sleep, Stroke, SDB, CPAP

  15. Measurement of the CKM matrix element vertical stroke Vts vertical stroke 2

    International Nuclear Information System (INIS)

    Unverdorben, Christopher Gerhard

    2015-03-01

    This is the first direct measurement of the CKM matrix element vertical stroke V ts vertical stroke, using data collected by the ATLAS detector in 2012 at √(s)= 8 TeV pp-collisions with a total integrated luminosity of 20.3 fb -1 . The analysis is based on 112 171 reconstructed t anti t candidate events in the lepton+jets channel, having a purity of 90.0 %. 183 t anti t→W + W - b anti s decays are expected (charge conjugation implied), which are available for the extraction of the CKM matrix element vertical stroke V ts vertical stroke 2 . To identify these rare decays, several observables are examined, such as the properties of jets, tracks and of b-quark identification algorithms. Furthermore, the s-quark hadrons K 0 s are considered, reconstructed by a kinematic fit. The best observables are combined in a multivariate analysis, called ''boosted decision trees''. The responses from Monte Carlo simulations are used as templates for a fit to data events yielding a significance value of 0.7σ for t→s+W decays. An upper limit of vertical stroke V ts vertical stroke 2 <1.74 % at 95 % confidence level is set, including all systematic and statistical uncertainties. So this analysis, using a direct measurement of the CKM matrix element vertical stroke V ts vertical stroke 2 , provides the best direct limit on vertical stroke V ts vertical stroke 2 up to now.

  16. Carotid IMT is more associated with stroke than risk calculators.

    Science.gov (United States)

    Owolabi, M O; Akpa, O M; Agunloye, A M

    2016-06-01

    It is unclear whether a natural marker of atherosclerosis (carotid intima-media thickness: CIMT) or calculated risk score is more associated with stroke. We therefore comparatively examined the relationship between CIMT as well as two cardiovascular risk calculators (Omnibus Risk Score -ORS and Framingham Risk Score- FRS) and the occurrence of stroke among hypertensive African patients. CIMT was measured in 555 consecutive consenting hypertensive adults (377 stroke patients and 178 stroke-free subjects). The 10-year cardiovascular risk was calculated for each participant with the FRS and ORS. The strengths of association between FRS, ORS, CIMT, and stroke occurrence were examined using logistic regression. The discriminative capacity of FRS, ORS, and CIMT for stroke occurrence was assessed with c-statistics. Higher average CIMT (OR 11.71; 95% CI 1.65-83.07; P = 0.01) was strongly associated with stroke after adjusting for age, sex, blood pressure, serum cholesterol, and blood sugar. Neither the FRS (OR: 1.03; CI: 0.89-1.19, P = 0.68) nor the ORS (OR: 1.08; CI: 0.90-1.30; P = 0.41) was significantly associated with stroke. CIMT had a higher c-statistic for differentiating stroke patients from hypertensive controls (right: c = 0.63, P < 0.001; left: c = 0.67, P < 0.001; average: c = 0.66, P < 0.001) than some conventional risk factors. Neither FRS (P = 0.39) nor ORS (P = 0.55) was able to independently differentiate between stroke and hypertensive patients. CIMT, but neither FRS nor ORS, is independently associated with stroke among Nigerian African hypertensive patients. CIMT may be a better tool for estimating the overall risk of stroke than FRS or ORS in this population. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  17. Comparison of Community Reintegration and Selected Stroke ...

    African Journals Online (AJOL)

    Community reintegration (CR) was assessed three months post-admission discharge using the Reintegration to Normal Living Index (RNLI). Demographic and stroke-specific characteristics were obtained using a data form. Data were analysed using descriptive statistics, the Mann-Whitney U test and the chi-square test.

  18. Stroke in Commercial Flights.

    Science.gov (United States)

    Álvarez-Velasco, Rodrigo; Masjuan, Jaime; DeFelipe, Alicia; Corral, Iñigo; Estévez-Fraga, Carlos; Crespo, Leticia; Alonso-Cánovas, Araceli

    2016-04-01

    Stroke on board aircraft has been reported in retrospective case series, mainly focusing on economy class stroke syndrome. Data on the actual incidence, pathogenesis, and prognosis of stroke in commercial flights are lacking. A prospective registry was designed to include all consecutive patients referred from an international airport (40 million passengers a year) to our hospital with a diagnosis of ischemic stroke or transient ischemic attack and onset of symptoms during a flight or immediately after landing. Forty-four patients (32 ischemic strokes and 12 transient ischemic attacks) were included over a 76-month period (January 2008 to April 2014). The estimated incidence of stroke was 1 stroke in 35 000 flights. Pathogeneses of stroke or transient ischemic attack were atherothrombotic in 16 (36%), economy class stroke syndrome in 8 (18%), cardioembolic in 7 (16%), arterial dissection in 4 (9%), lacunar stroke in 4 (9%), and undetermined in 5 (12%) patients. Carotid stenosis >70% was found in 12 (27%) of the patients. Overall prognosis was good, and thrombolysis was applied in 44% of the cases. The most common reason for not treating patients who had experienced stroke onset midflight was the delay in reaching the hospital. Only 1 patient with symptom onset during the flight prompted a flight diversion. We found a low incidence of stroke in the setting of air travel. Economy class stroke syndrome and arterial dissection were well represented in our sample. However, the main pathogenesis was atherothrombosis with a high proportion of patients with high carotid stenosis. © 2016 American Heart Association, Inc.

  19. Stroke And Substance Abuse

    Directory of Open Access Journals (Sweden)

    A Chitsaz

    2017-02-01

    Full Text Available Introduction: stroke in recreational substance users can be an indirect complication, like endocarditis and cardio embolism in parenteral drug users. With some drug like cocaine, stroke appear to be the result of a direct effect. In young subjects without other risk factors provide persuasive evidence for causality . OPIATES: Heroine is the most abused opiate drug, which is administered by injection, by snorting or by smoking. Stroke affects heroin users by diverse mechanisms,. Injectors are at risk of infections endocarditis, which carries risk for both ischemic and hemorrhagic stroke. Cerebral or subarachnoid hemorrhage usually occurs after rupture of a septic (mycotic aneurysm. Heroine users can are also at risk for hemorrhagic stroke secondary to liver failure with deranged clotting and to heroin nephropathy with uremia or malignant hypertension. In some heroin users the drug it self is directly causal due to vasculitis, hypersensitivity and immunologic changes. Embolization of foreign material to brain due to mixed of heroine with quinine can cause cerebral embolism. AMPHETAMINE AND other psychostimulants: In abuser of amphetamine hemorrhagic stroke can occur, oral, intravenous, nasal, and inhalational routes of administration have been reported. Most were chronic user, but in several patients, stroke followed a first exposure. Some of amphetamine induced intracranial hemorrhages are secondary to acute hypertension, some to cerebral vacuities, and some to a combination of two. Decongestants and diet pills: Phenylpropanolamine (PPA, an amphetamine – like drug, in decongestants and diet pills, induce acute hypertension, sever headache, psychiatric symptoms, seizures and hemorrhagic stroke. Ephedrine and pseudo ephedrine are present in decongestants and bronchodilators and induce headache, tachyarrhythmia, hypertensive emergency, and hemorrhagic and occlusive stroke. Ecstasy, 3,4 Methylenedioxymethamphetamin (MDMA with amphetamine like can

  20. Workup for Perinatal Stroke Does Not Predict Recurrence.

    Science.gov (United States)

    Lehman, Laura L; Beaute, Jeanette; Kapur, Kush; Danehy, Amy R; Bernson-Leung, Miya E; Malkin, Hayley; Rivkin, Michael J; Trenor, Cameron C

    2017-08-01

    Perinatal stroke, including neonatal and presumed perinatal presentation, represents the age in childhood in which stroke occurs most frequently. The roles of thrombophilia, arteriopathy, and cardiac anomalies in perinatal ischemic stroke are currently unclear. We took a uniform approach to perinatal ischemic stroke evaluation to study these risk factors and their association with recurrent stroke. We reviewed records of perinatal stroke patients evaluated from August 2008 to February 2016 at a single referral center. Demographics, echocardiography, arterial imaging, and thrombophilia testing were collected. Statistical analysis was performed using Fisher exact test. Across 215 cases, the median follow-up was 3.17 years (1.49, 6.46). Females comprised 42.8% of cases. Age of presentation was neonatal (110, 51.2%) or presumed perinatal (105, 48.8%). The median age at diagnosis was 2.9 days (interquartile range, 2.0-9.9) for neonatal stroke and 12.9 months (interquartile range, 8.7-32.8) for presumed perinatal stroke. Strokes were classified as arterial (149, 69.3%), venous (60, 27.9%), both (4, 1.9%), or uncertain (2, 0.9%) by consensus imaging review. Of the 215 cases, there were 6 (2.8%) recurrent ischemic cerebrovascular events. Abnormal thrombophilia testing was not associated with recurrent stroke, except for a single patient with combined antithrombin deficiency and protein C deficiency. After excluding venous events, 155 patients were evaluated for arteriopathy and cardioembolic risk factors; neither was associated with recurrent stroke. Positive family history of thrombosis was not predictive of abnormal thrombophilia testing. Thrombophilia, arteriopathy, or cardioembolic risk factors were not predictive of recurrent events after perinatal stroke. Thrombophilia evaluation in perinatal stroke should only rarely be considered. © 2017 American Heart Association, Inc.

  1. Sequential strokes in a hyperacute stroke unit.

    Science.gov (United States)

    Ganesalingam, Jeban; Buddha, Sandeep; Carlton-Jones, Anoma L; Nicholas, Richard

    2014-08-01

    Vasculitis is a rare, but treatable condition that can present to hyperacute stroke units. Thrombolysis does not treat the underlying pathology, and a rapidly evolving clinical picture drives clinical decision often before all the investigation results are available.

  2. Statistical analysis of the electric energy production from photovoltaic conversion using mobile and fixed constructions

    Directory of Open Access Journals (Sweden)

    Bugała Artur

    2017-01-01

    Full Text Available The paper presents the most representative – from the three-year measurement time period – characteristics of daily and monthly electricity production from a photovoltaic conversion using modules installed in a fixed and 2-axis tracking construction. Results are presented for selected summer, autumn, spring and winter days. Analyzed measuring stand is located on the roof of the Faculty of Electrical Engineering Poznan University of Technology building. The basic parameters of the statistical analysis like mean value, standard deviation, skewness, kurtosis, median, range, or coefficient of variation were used. It was found that the asymmetry factor can be useful in the analysis of the daily electricity production from a photovoltaic conversion. In order to determine the repeatability of monthly electricity production, occurring between the summer, and summer and winter months, a non-parametric Mann-Whitney U test was used as a statistical solution. In order to analyze the repeatability of daily peak hours, describing the largest value of the hourly electricity production, a non-parametric Kruskal-Wallis test was applied as an extension of the Mann-Whitney U test. Based on the analysis of the electric energy distribution from a prepared monitoring system it was found that traditional forecasting methods of the electricity production from a photovoltaic conversion, like multiple regression models, should not be the preferred methods of the analysis.

  3. Clinicoanatomical correlation in stroke related aphasia

    Directory of Open Access Journals (Sweden)

    Vikram Bohra

    2015-01-01

    Full Text Available Context: With advances in neuroimaging, traditional views regarding the clinicoanatomic correlation in stroke patients with aphasia are being challenged and it has been observed that lesions at a given cortical or subcortical site may manifest with different aphasia profiles. Aims: To study as to whether there is a strict clinicoanatomical correlation between the type of aphasia and lesion site in patients with first ever stroke. Settings and Design: Observational study, based in a tertiary care center. Materials and Methods: Stroke patient′s ≥18 years of age were screened and those with first ever stroke and aphasia were subjected to a detailed stroke workup and language assessment using the Hindi version of Western Aphasia Battery (WAB. Statistical analysis was done with χ2 test with Yates correction and Kruskal-Wallis test. The level of significance was set at P < 0.05. Results: Overall aphasia was detected in 27.9% of the 260 screened cases with stroke. Amongst 60 cases with first ever stroke and aphasia, the aphasia type was: Global (33.33%, Broca′s (28.3%, transcortical motor (13.33%, transcortical sensory (10%, Wernicke′s (8.33%, anomic (5%, and conduction (1.67% aphasia. A definite correlation between the lesion site and the type of aphasia as per the traditional classification was observed in 35% cases only. Conclusions: No absolute correlation exists between the lesion site and the type of clinical aphasia syndrome in majority of the patients with cortical and subcortical stroke.

  4. Blood Pressure Control: Stroke and Stroke Prevention

    Directory of Open Access Journals (Sweden)

    Hans-Christoph Diener

    2005-03-01

    Full Text Available Hypertension is the most important modifiable risk factor for primary and secondary stroke prevention.All antihypertensive drugs are effective in primary prevention: the risk reduction for stroke is 30—42%. However, not all classes of drugs have the same effects: there is some indication that angiotensin receptor blockers may be superior to other classes of antihypertensive drugs in stroke prevention.Seventy-five percent of patients who present to hospital with acute stroke have elevated blood pressure within the first 24—48 hours. Extremes of systolic blood pressure (SBP increase the risk of death or dependency. The aim of treatment should be to achieve and maintain the SBP in the range 140—160 mmHg. However, fast and drastic blood pressure lowering can have adverse consequences.The PROGRESS trial of secondary prevention with perindopril + indapamide versus placebo + placebo showed a decrease in numbers of stroke recurrences in patients given both active antihypertensive agents, more impressive for cerebral haemorrhage.There were also indications that active treatment might decrease the development of post-stroke dementia.

  5. Sex differences in stroke: a socioeconomic perspective

    Directory of Open Access Journals (Sweden)

    Delbari A

    2016-09-01

    Full Text Available Ahmad Delbari,1 Farzane Keyghobadi,2 Yadollah Abolfathi Momtaz,1,3 Fariba Keyghobadi,2 Reza Akbari,2 Houman Kamranian,2 Mohammad Shouride Yazdi,2 Sayed Shahaboddin Tabatabaei,1 Seyed-Mohammad Fereshtehnejad4 1Iranian Research Center on Aging, University of Social Welfare and Rehabilitation Sciences, Tehran, Iran; 2Research Center on Healthy Aging, Sabzevar University of Medical Sciences, Sabzevar, Khorasan, Iran; 3Malaysian Research Institute on Ageing (MyAgeing™, Universiti Putra Malaysia, Serdang, Selangor, Malaysia; 4Department of Neurobiology, Division of Clinical Geriatrics, Care Sciences and Society (NVS, Karolinska Institutet, Stockholm, Sweden Background: A number of studies have explored the issue of sex differences in stroke from biomedical perspective; however, there are still large gaps in the existing knowledge. The purpose of this study was to assess whether the differences in socioeconomic status and living conditions between men and women may explain the part of the sex differences in incidence and outcomes of stroke. Methods: All stroke participants aged ≥60 years admitted in Vaseie Hospital in Sabzevar, Iran, from March 21, 2013, until March 20, 2014, were included in this study. Computerized tomography and magnetic resonance imaging were used to confirm stroke. A series of χ2 tests were performed and Statistical Program for Social Sciences, Version 21.0, was used to investigate the potential differences between older men and women in stroke incidence and outcomes. Results: A total of 159 incident stroke cases were documented during 1 year. The annual rate of stroke was statistically significantly higher in elderly women than in elderly men (401 vs 357 per 100,000; P<0.001. Female elderly participants had significantly lower socioeconomic status, poorer living conditions, and higher lifetime history of depression, hypertension, and diabetes mellitus than their male counterparts. Conclusion: The findings from this study

  6. Knowledge of Stroke Risk Factors among Stroke Survivors in Nigeria

    OpenAIRE

    Grace Vincent-Onabajo; Taritei Moses

    2016-01-01

    Background. Knowledge of stroke risk factors is expected to reduce the incidence of stroke?whether first-ever or recurrent. This study examined knowledge of stroke risk factors and its determinants among stroke survivors. Methods. A cross-sectional survey of consenting stroke survivors at two physiotherapy facilities in Nigeria was carried out. Sociodemographic and clinical data were obtained and knowledge of stroke risk factors (defined as the ability to mention at least one correct risk fac...

  7. European Stroke Science Workshop

    Science.gov (United States)

    Mattle, Heinrich P.; Brainin, Michael; Chamorro, Angel; Diener, Hans Christoph; Hacke, Werner; Leys, Didier; Norrving, Bo; Ward, Nick

    2012-01-01

    The European Stroke Organisation (ESO) held its first European Stroke Science Workshop in Garmisch-Partenkirchen, Germany (15-17 December 2011). Stroke experts based in Europe were invited to present and discuss their current research. The scope of the workshop was to review the most recent findings of selected topics in stroke, to exchange ideas, to stimulate new research and to enhance collaboration between European stroke research groups. Seven scientific sessions were held, each starting with a keynote lecture to review the state of the art of the given topic, followed by 4 or 5 short presentations by experts. They were asked to limit their presentations to 10 slides containing only recent information. The meeting was organized by the executive committee of the ESO (Heinrich Mattle, chairman, Michael Brainin, Angel Chamorro, Werner Hacke, Didier Leys) and supported by the European Stroke Conference (Michael Hennerici). In this article we summarize the main contents of this successful workshop. PMID:22836350

  8. Acute stroke imaging research roadmap

    NARCIS (Netherlands)

    Wintermark, Max; Albers, Gregory W.; Alexandrov, Andrei V.; Alger, Jeffry R.; Bammer, Roland; Baron, Jean-Claude; Davis, Stephen; Demaerschalk, Bart M.; Derdeyn, Colin P.; Donnan, Geoffrey A.; Eastwood, James D.; Fiebach, Jochen B.; Fisher, Marc; Furie, Karen L.; Goldmakher, Gregory V.; Hacke, Werner; Kidwell, Chelsea S.; Kloska, Stephan P.; Koehrmann, Martin; Koroshetz, Walter; Lee, Ting-Yim; Lees, Kennedy R.; Lev, Michael H.; Liebeskind, David S.; Ostergaard, Leif; Powers, William J.; Provenzale, James; Schellinger, Peter; Silbergleit, Robert; Sorensen, Alma Gregory; Wardlaw, Joanna; Warach, Steven

    The recent "Advanced Neuroimaging for Acute Stroke Treatment" meeting on September 7 and 8, 2007 in Washington DC, brought together stroke neurologists, neuroradiologists, emergency physicians, neuroimaging research scientists, members of the National Institute of Neurological Disorders and Stroke

  9. Revised Framingham Stroke Risk Score, Nontraditional Risk Markers, and Incident Stroke in a Multiethnic Cohort.

    Science.gov (United States)

    Flueckiger, Peter; Longstreth, Will; Herrington, David; Yeboah, Joseph

    2018-02-01

    Limited data exist on the performance of the revised Framingham Stroke Risk Score (R-FSRS) and the R-FSRS in conjunction with nontraditional risk markers. We compared the R-FSRS, original FSRS, and the Pooled Cohort Equation for stroke prediction and assessed the improvement in discrimination by nontraditional risk markers. Six thousand seven hundred twelve of 6814 participants of the MESA (Multi-Ethnic Study of Atherosclerosis) were included. Cox proportional hazard, area under the curve, net reclassification improvement, and integrated discrimination increment analysis were used to assess and compare each stroke prediction risk score. Stroke was defined as fatal/nonfatal strokes (hemorrhagic or ischemic). After mean follow-up of 10.7 years, 231 of 6712 (3.4%) strokes were adjudicated (2.7% ischemic strokes). Mean stroke risks using the R-FSRS, original FSRS, and Pooled Cohort Equation were 4.7%, 5.9%, and 13.5%. The R-FSRS had the best calibration (Hosmer-Lemeshow goodness-of-fit, χ 2 =6.55; P =0.59). All risk scores were predictive of incident stroke. C statistics of R-FSRS (0.716) was similar to Pooled Cohort Equation (0.716), but significantly higher than the original FSRS (0.653; P =0.01 for comparison with R-FSRS). Adding nontraditional risk markers individually to the R-FSRS did not improve discrimination of the R-FSRS in the area under the curve analysis, but did improve category-less net reclassification improvement and integrated discrimination increment for incident stroke. The addition of coronary artery calcium to R-FSRS produced the highest category-less net reclassification improvement (0.36) and integrated discrimination increment (0.0027). Similar results were obtained when ischemic strokes were used as the outcome. The R-FSRS downgraded stroke risk but had better calibration and discriminative ability for incident stroke compared with the original FSRS. Nontraditional risk markers modestly improved the discriminative ability of the R-FSRS, with

  10. Harmonic statistics

    Science.gov (United States)

    Eliazar, Iddo

    2017-05-01

    The exponential, the normal, and the Poisson statistical laws are of major importance due to their universality. Harmonic statistics are as universal as the three aforementioned laws, but yet they fall short in their 'public relations' for the following reason: the full scope of harmonic statistics cannot be described in terms of a statistical law. In this paper we describe harmonic statistics, in their full scope, via an object termed harmonic Poisson process: a Poisson process, over the positive half-line, with a harmonic intensity. The paper reviews the harmonic Poisson process, investigates its properties, and presents the connections of this object to an assortment of topics: uniform statistics, scale invariance, random multiplicative perturbations, Pareto and inverse-Pareto statistics, exponential growth and exponential decay, power-law renormalization, convergence and domains of attraction, the Langevin equation, diffusions, Benford's law, and 1/f noise.

  11. Body Mass Index and Stroke

    DEFF Research Database (Denmark)

    Andersen, Klaus Kaae; Olsen, Tom Skyhøj

    2013-01-01

    Although obesity is associated with excess mortality and morbidity, mortality is lower in obese than in normal weight stroke patients (the obesity paradox). Studies now indicate that obesity is not associated with increased risk of recurrent stroke in the years after first stroke. We studied the ...... the association between body mass index (BMI) and stroke patient's risk of having a history of previous stroke (recurrent stroke)....

  12. Spontaneous ischaemic stroke in dogs

    DEFF Research Database (Denmark)

    Gredal, Hanne Birgit; Skerritt, G. C.; Gideon, P.

    2013-01-01

    Translation of experimental stroke research into the clinical setting is often unsuccessful. Novel approaches are therefore desirable. As humans, pet dogs suffer from spontaneous ischaemic stroke and may hence offer new ways of studying genuine stroke injury mechanisms.......Translation of experimental stroke research into the clinical setting is often unsuccessful. Novel approaches are therefore desirable. As humans, pet dogs suffer from spontaneous ischaemic stroke and may hence offer new ways of studying genuine stroke injury mechanisms....

  13. Prehospital Management of Acute Stroke in Rural versus Urban Responders.

    Science.gov (United States)

    Hansen, Gregory; Bal, Simerpreet; Schellenberg, Kerri Lynn; Alcock, Susan; Ghrooda, Esseddeeg

    2017-08-01

    Stroke guideline compliance of rural Canadian prehospital emergency medical services (EMS) care in acute stroke is unknown. In this quality assurance study, we sought to compare rural and urban care by prehospital EMS evaluation/management indicators from patients assessed at an urban Canadian stroke center. One hundred adult patients were randomly selected from the stroke registry. Patients were transported through Rural EMS bypass protocols or urban EMS protocols (both bypass and direct) to our stroke center between January and December 2013. Patients were excluded if they were first evaluated at any other health center. Prehospital care was assessed using ten indicators for EMS evaluation/management, as recommended by acute stroke guidelines. Compliance with acute stroke EMS evaluation/management indicators were statistically similar for both groups, except administrating a prehospital diagnostic tool (rural 31.8 vs. urban 70.3%; P = 0.002). Unlike urban EMS, rural EMS did not routinely document scene time. Rural EMS responders' compliance to prehospital stroke evaluation/management was similar to urban EMS responders. Growth areas for both groups may be with prehospital stroke diagnostic tool utilization, whereas rural EMS responders may also improve with scene time documentation.

  14. Prehospital management of acute stroke in rural versus urban responders

    Directory of Open Access Journals (Sweden)

    Gregory Hansen

    2017-01-01

    Full Text Available Objective: Stroke guideline compliance of rural Canadian prehospital emergency medical services (EMS care in acute stroke is unknown. In this quality assurance study, we sought to compare rural and urban care by prehospital EMS evaluation/management indicators from patients assessed at an urban Canadian stroke center. Materials and Methods: One hundred adult patients were randomly selected from the stroke registry. Patients were transported through Rural EMS bypass protocols or urban EMS protocols (both bypass and direct to our stroke center between January and December 2013. Patients were excluded if they were first evaluated at any other health center. Prehospital care was assessed using ten indicators for EMS evaluation/management, as recommended by acute stroke guidelines. Results: Compliance with acute stroke EMS evaluation/management indicators were statistically similar for both groups, except administrating a prehospital diagnostic tool (rural 31.8 vs. urban 70.3%; P = 0.002. Unlike urban EMS, rural EMS did not routinely document scene time. Conclusion: Rural EMS responders' compliance to prehospital stroke evaluation/management was similar to urban EMS responders. Growth areas for both groups may be with prehospital stroke diagnostic tool utilization, whereas rural EMS responders may also improve with scene time documentation.

  15. Obesity increases risk of ischemic stroke in young adults.

    Science.gov (United States)

    Mitchell, Andrew B; Cole, John W; McArdle, Patrick F; Cheng, Yu-Ching; Ryan, Kathleen A; Sparks, Mary J; Mitchell, Braxton D; Kittner, Steven J

    2015-06-01

    Body mass index has been associated with ischemic stroke in older populations, but its association with stroke in younger populations is not known. In light of the current obesity epidemic in the United States, the potential impact of obesity on stroke risk in young adults deserves attention. A population-based case-control study design with 1201 cases and 1154 controls was used to investigate the relationship of obesity and young onset ischemic stroke. Stroke cases were between the ages of 15 and 49 years. Logistic regression analysis was used to evaluate the association between body mass index and ischemic stroke with and without adjustment for comorbid conditions associated with stroke. In analyses adjusted for age, sex, and ethnicity, obesity (body mass index >30 kg/m(2)) was associated with an increased stroke risk (odds ratio, 1.57; 95% confidence interval, 1.28-1.94) although this increased risk was highly attenuated and not statistically significant after adjustment for smoking, hypertension, and diabetes mellitus. These results indicate that obesity is a risk factor for young onset ischemic stroke and suggest that this association may be partially mediated through hypertension, diabetes mellitus, or other variables associated with these conditions. © 2015 American Heart Association, Inc.

  16. Statistical Analysis for High-Dimensional Data : The Abel Symposium 2014

    CERN Document Server

    Bühlmann, Peter; Glad, Ingrid; Langaas, Mette; Richardson, Sylvia; Vannucci, Marina

    2016-01-01

    This book features research contributions from The Abel Symposium on Statistical Analysis for High Dimensional Data, held in Nyvågar, Lofoten, Norway, in May 2014. The focus of the symposium was on statistical and machine learning methodologies specifically developed for inference in “big data” situations, with particular reference to genomic applications. The contributors, who are among the most prominent researchers on the theory of statistics for high dimensional inference, present new theories and methods, as well as challenging applications and computational solutions. Specific themes include, among others, variable selection and screening, penalised regression, sparsity, thresholding, low dimensional structures, computational challenges, non-convex situations, learning graphical models, sparse covariance and precision matrices, semi- and non-parametric formulations, multiple testing, classification, factor models, clustering, and preselection. Highlighting cutting-edge research and casting light on...

  17. Implementation of a stroke registry is associated with an improvement in stroke performance measures in a tertiary hospital in Mexico.

    Science.gov (United States)

    Herrera, Ana Lucia; Góngora-Rivera, Fernando; Muruet, Walter; Villarreal, Héctor Jorge; Gutiérrez-Herrera, Mildred; Huerta, Lena; Carrasco, Diana; Soto-García, Anally; Espinosa-Ortega, Meztli

    2015-04-01

    Stroke registries provide a simple way for improving patient care, and its use has been associated with a better adherence to the published guidelines. Few Latin American countries had established stroke registries. Our study is the first in Mexico to report the effects of implementing a stroke registry. To determine if the implementation of a systematized registry is associated with an improved adherence to the performance measures. We compared prospective data (August 2008-November 2010) against historical controls (February 2005-July 2008). Our stroke registry (i-Registro Neurovascular) consists of a standardized clinical form that includes demographic and clinical variables (risk factors, medications, neuroimaging, etiology, acute and outpatient treatments, and neurologic scores [National Institutes of Health Stroke Scale and modified Rankin Scale]). We evaluated 9 performance measures suggested by the American Heart Association and the Joint Commission. We analyzed the data from 574 patients, 260 from the prospective phase and 314 from historical controls. No significant statistical differences in demographic characteristics or stroke risk factors were found. The implementation of the stroke registry was associated with a statistically significant (P cost and readily achievable and a viable option for encouraging an increased report of guidelines adherence of other hospitals in Latin America. Copyright © 2015 National Stroke Association. Published by Elsevier Inc. All rights reserved.

  18. An augmented reality system for upper-limb post-stroke motor rehabilitation: a feasibility study.

    Science.gov (United States)

    Assis, Gilda Aparecida de; Corrêa, Ana Grasielle Dionísio; Martins, Maria Bernardete Rodrigues; Pedrozo, Wendel Goes; Lopes, Roseli de Deus

    2016-08-01

    To determine the clinical feasibility of a system based on augmented reality for upper-limb (UL) motor rehabilitation of stroke participants. A physiotherapist instructed the participants to accomplish tasks in augmented reality environment, where they could see themselves and their surroundings, as in a mirror. Two case studies were conducted. Participants were evaluated pre- and post-intervention. The first study evaluated the UL motor function using Fugl-Meyer scale. Data were compared using non-parametric sign tests and effect size. The second study used the gain of motion range of shoulder flexion and abduction assessed by computerized biophotogrammetry. At a significance level of 5%, Fugl-Meyer scores suggested a trend for greater UL motor improvement in the augmented reality group than in the other. Moreover, effect size value 0.86 suggested high practical significance for UL motor rehabilitation using the augmented reality system. System provided promising results for UL motor rehabilitation, since enhancements have been observed in the shoulder range of motion and speed. Implications for Rehabilitation Gain of range of motion of flexion and abduction of the shoulder of post-stroke patients can be achieved through an augmented reality system containing exercises to promote the mental practice. NeuroR system provides a mental practice method combined with visual feedback for motor rehabilitation of chronic stroke patients, giving the illusion of injured upper-limb (UL) movements while the affected UL is resting. Its application is feasible and safe. This system can be used to improve UL rehabilitation, an additional treatment past the traditional period of the stroke patient hospitalization and rehabilitation.

  19. Development of infill drilling recovery models for carbonates reservoirs using neural networks and multivariate statistical as a novel method

    International Nuclear Information System (INIS)

    Soto, R; Wu, Ch. H; Bubela, A M

    1999-01-01

    This work introduces a novel methodology to improve reservoir characterization models. In this methodology we integrated multivariate statistical analyses, and neural network models for forecasting the infill drilling ultimate oil recovery from reservoirs in San Andres and Clearfork carbonate formations in west Texas. Development of the oil recovery forecast models help us to understand the relative importance of dominant reservoir characteristics and operational variables, reproduce recoveries for units included in the database, forecast recoveries for possible new units in similar geological setting, and make operational (infill drilling) decisions. The variety of applications demands the creation of multiple recovery forecast models. We have developed intelligent software (Soto, 1998), oilfield intelligence (01), as an engineering tool to improve the characterization of oil and gas reservoirs. 01 integrates neural networks and multivariate statistical analysis. It is composed of five main subsystems: data input, preprocessing, architecture design, graphic design, and inference engine modules. One of the challenges in this research was to identify the dominant and the optimum number of independent variables. The variables include porosity, permeability, water saturation, depth, area, net thickness, gross thickness, formation volume factor, pressure, viscosity, API gravity, number of wells in initial water flooding, number of wells for primary recovery, number of infill wells over the initial water flooding, PRUR, IWUR, and IDUR. Multivariate principal component analysis is used to identify the dominant and the optimum number of independent variables. We compared the results from neural network models with the non-parametric approach. The advantage of the non-parametric regression is that it is easy to use. The disadvantage is that it retains a large variance of forecast results for a particular data set. We also used neural network concepts to develop recovery

  20. Evaluation of stroke services in Anglia stroke clinical network to examine the variation in acute services and stroke outcomes

    Directory of Open Access Journals (Sweden)

    George Abraham

    2011-02-01

    Full Text Available Abstract Background Stroke is the third leading cause of death in developed countries and the leading cause of long-term disability worldwide. A series of national stroke audits in the UK highlighted the differences in stroke care between hospitals. The study aims to describe variation in outcomes following stroke and to identify the characteristics of services that are associated with better outcomes, after accounting for case mix differences and individual prognostic factors. Methods/Design We will conduct a cohort study in eight acute NHS trusts within East of England, with at least one year of follow-up after stroke. The study population will be a systematically selected representative sample of patients admitted with stroke during the study period, recruited within each hospital. We will collect individual patient data on prognostic characteristics, health care received, outcomes and costs of care and we will also record relevant characteristics of each provider organisation. The determinants of one year outcome including patient reported outcome will be assessed statistically with proportional hazards regression models. Self (or proxy completed EuroQol (EQ-5D questionnaires will measure quality of life at baseline and follow-up for cost utility analyses. Discussion This study will provide observational data about health service factors associated with variations in patient outcomes and health care costs following hospital admission for acute stroke. This will form the basis for future RCTs by identifying promising health service interventions, assessing the feasibility of recruiting and following up trial patients, and provide evidence about frequency and variances in outcomes, and intra-cluster correlation of outcomes, for sample size calculations. The results will inform clinicians, public, service providers, commissioners and policy makers to drive further improvement in health services which will bring direct benefit to the patients.

  1. Statistical physics

    CERN Document Server

    Sadovskii, Michael V

    2012-01-01

    This volume provides a compact presentation of modern statistical physics at an advanced level. Beginning with questions on the foundations of statistical mechanics all important aspects of statistical physics are included, such as applications to ideal gases, the theory of quantum liquids and superconductivity and the modern theory of critical phenomena. Beyond that attention is given to new approaches, such as quantum field theory methods and non-equilibrium problems.

  2. Harmonic statistics

    Energy Technology Data Exchange (ETDEWEB)

    Eliazar, Iddo, E-mail: eliazar@post.tau.ac.il

    2017-05-15

    The exponential, the normal, and the Poisson statistical laws are of major importance due to their universality. Harmonic statistics are as universal as the three aforementioned laws, but yet they fall short in their ‘public relations’ for the following reason: the full scope of harmonic statistics cannot be described in terms of a statistical law. In this paper we describe harmonic statistics, in their full scope, via an object termed harmonic Poisson process: a Poisson process, over the positive half-line, with a harmonic intensity. The paper reviews the harmonic Poisson process, investigates its properties, and presents the connections of this object to an assortment of topics: uniform statistics, scale invariance, random multiplicative perturbations, Pareto and inverse-Pareto statistics, exponential growth and exponential decay, power-law renormalization, convergence and domains of attraction, the Langevin equation, diffusions, Benford’s law, and 1/f noise. - Highlights: • Harmonic statistics are described and reviewed in detail. • Connections to various statistical laws are established. • Connections to perturbation, renormalization and dynamics are established.

  3. Statistical optics

    CERN Document Server

    Goodman, Joseph W

    2015-01-01

    This book discusses statistical methods that are useful for treating problems in modern optics, and the application of these methods to solving a variety of such problems This book covers a variety of statistical problems in optics, including both theory and applications.  The text covers the necessary background in statistics, statistical properties of light waves of various types, the theory of partial coherence and its applications, imaging with partially coherent light, atmospheric degradations of images, and noise limitations in the detection of light. New topics have been introduced i

  4. Statistical methods

    CERN Document Server

    Szulc, Stefan

    1965-01-01

    Statistical Methods provides a discussion of the principles of the organization and technique of research, with emphasis on its application to the problems in social statistics. This book discusses branch statistics, which aims to develop practical ways of collecting and processing numerical data and to adapt general statistical methods to the objectives in a given field.Organized into five parts encompassing 22 chapters, this book begins with an overview of how to organize the collection of such information on individual units, primarily as accomplished by government agencies. This text then

  5. Immune interventions in stroke

    Science.gov (United States)

    Fu, Ying; Liu, Qiang; Anrather, Josef

    2016-01-01

    Inflammatory and immune responses in the brain can shape the clinical presentation and outcome of stroke. Approaches for effective management of acute stroke are sparse and many measures for brain protection fail, but our ability to modulate the immune system and modify the disease progression of multiple sclerosis is increasing. As a result, immune interventions are currently being explored as therapeutic interventions in acute stroke. In this Review, we compare the immunological features of acute stroke with those of multiple sclerosis, identify unique immunological features of stroke, and consider the evidence for immune interventions. In acute stroke, microglia activation and cell death products trigger an inflammatory cascade that damages vessels and the parenchyma within minutes to hours of the ischaemia or haemorrhage. Immune interventions that restrict brain inflammation, vascular permeability and tissue oedema must be administered rapidly to reduce acute immune-mediated destruction and to avoid subsequent immunosuppression. Preliminary results suggest that the use of drugs that modify disease in multiple sclerosis might accomplish these goals in ischaemic and haemorrhagic stroke. Further elucidation of the immune mechanisms involved in stroke is likely to lead to successful immune interventions. PMID:26303850

  6. Relational Processing Following Stroke

    Science.gov (United States)

    Andrews, Glenda; Halford, Graeme S.; Shum, David; Maujean, Annick; Chappell, Mark; Birney, Damian

    2013-01-01

    The research examined relational processing following stroke. Stroke patients (14 with frontal, 30 with non-frontal lesions) and 41 matched controls completed four relational processing tasks: sentence comprehension, Latin square matrix completion, modified Dimensional Change Card Sorting, and n-back. Each task included items at two or three…

  7. National Stroke Association

    Science.gov (United States)

    ... Event Join a Stroke Challenge Team Comeback Trail Tell Your Story Community Presentations Faces of Stroke Volunteer With Us ... in a video presentation. Watch Video ... to feel the right side of her body. Kathryn’s friends performed the FAST exam and soon ...

  8. Diagnostic neuroimaging in stroke

    International Nuclear Information System (INIS)

    Jarenwattananon, A.; Khandji, A.; Brust, J.C.M.

    1988-01-01

    Since the development of cerebral angiography 60 years ago, there has been a proliferation of increasingly sophisticated, expensive, and, fortunately, safe imaging techniques for patients with cerebrovascular disease. In addition, occlusive and hemorrhagic stroke are now recognized as having a wide variety of possible causes. This chapter addresses the different imaging options available for particular kinds of stroke

  9. The Optimal Golf Stroke

    DEFF Research Database (Denmark)

    Buchinger, Mikael; Durigen, Susan; Dahl, Johan Rambech

    2006-01-01

    The paper presents a preliminary investigation into aspects of the game of golf. A series of models is proposed for the golf stroke, the momentum transfer between club and ball and the flight of the ball.Numerical and asymptotic solutions are presented reproducing many of the features observed...... in the golf stroke of a professional golfer....

  10. Comparison of serum lipid profile in ischaemic and haemorrhagic stroke

    International Nuclear Information System (INIS)

    Mehmood, A.; Sharif, M.A.

    2010-01-01

    To compare serum lipid profile between patients of ischaemic and haemorrhagic strokes. Study Design: Cross sectional, comparative study. Place and Duration of Study: Military Hospital, Rawalpindi, from August 2004 to February 2005. Methodology: Patients with diagnosis of stroke comprising 100 consecutive patients each of ischaemic and haemorrhagic strokes were included in the study while patients on lipid lowering therapy were excluded from study. To determine the subtype of stroke, clinical examination followed by CT scan of brain was done. A serum sample after 8 hours of overnight fasting was taken on the next day of admission for both groups of patients. Total serum cholesterol, triglycerides, LDL cholesterol, VLDL-cholesterol and HDL-cholesterol was determined, using enzymatic colorimetric method. Statistical analysis was done by comparison of lipid profile in two subgroups, using proportion test for any significant difference. Results: The mean age at presentation of patients with stroke was 64.2+-12 years with a male to female ratio of 3.6:1. In 100 ischaemic stroke patients, raised serum total cholesterol was seen in 42, triglyceride in 04, LDL-cholesterol in 05 and VLDL-cholesterol in 07 patients. Serum HDL-cholesterol was below the normal reference in 31 cases. On the other hand, serum total cholesterol and triglycerides was raised in 05 patients each, LDL-cholesterol in 09 and VLDL-cholesterol in 03 patients of haemorrhagic stroke. Serum HDL-cholesterol was below normal in 04 patients of haemorrhagic stroke. On comparison, there were significantly greater number of patients with raised serum cholesterol and low HDL-cholesterol in ischaemic stroke than haemorrhagic stroke (p < 0.05). No statistical significance was found on comparing serum values of ischaemic and haemorrhagic stroke for triglycerides, LDL-cholesterol and VLDL-cholesterol. Conclusion: Ischaemic stroke patients had high serum total cholesterol and lower HDL-cholesterol levels as compared to

  11. Acute ischemic stroke update.

    Science.gov (United States)

    Baldwin, Kathleen; Orr, Sean; Briand, Mary; Piazza, Carolyn; Veydt, Annita; McCoy, Stacey

    2010-05-01

    Stroke is the third most common cause of death in the United States and is the number one cause of long-term disability. Legislative mandates, largely the result of the American Heart Association, American Stroke Association, and Brain Attack Coalition working cooperatively, have resulted in nationwide standardization of care for patients who experience a stroke. Transport to a skilled facility that can provide optimal care, including immediate treatment to halt or reverse the damage caused by stroke, must occur swiftly. Admission to a certified stroke center is recommended for improving outcomes. Most strokes are ischemic in nature. Acute ischemic stroke is a heterogeneous group of vascular diseases, which makes targeted treatment challenging. To provide a thorough review of the literature since the 2007 acute ischemic stroke guidelines were developed, we performed a search of the MEDLINE database (January 1, 2004-July 1, 2009) for relevant English-language studies. Results (through July 1, 2009) from clinical trials included in the Internet Stroke Center registry were also accessed. Results from several pivotal studies have contributed to our knowledge of stroke. Additional data support the efficacy and safety of intravenous alteplase, the standard of care for acute ischemic stroke since 1995. Due to these study results, the American Stroke Association changed its recommendation to extend the time window for administration of intravenous alteplase from within 3 hours to 4.5 hours of symptom onset; this recommendation enables many more patients to receive the drug. Other findings included clinically useful biomarkers, the role of inflammation and infection, an expanded role for placement of intracranial stents, a reduced role for urgent carotid endarterectomy, alternative treatments for large-vessel disease, identification of nontraditional risk factors, including risk factors for women, and newly published pediatric stroke guidelines. In addition, new devices for

  12. The Danish Stroke Registry

    DEFF Research Database (Denmark)

    Johnsen, Søren Paaske; Ingeman, Annette; Hundborg, Heidi Holmager

    2016-01-01

    AIM OF DATABASE: The aim of the Danish Stroke Registry is to monitor and improve the quality of care among all patients with acute stroke and transient ischemic attack (TIA) treated at Danish hospitals. STUDY POPULATION: All patients with acute stroke (from 2003) or TIA (from 2013) treated...... at Danish hospitals. Reporting is mandatory by law for all hospital departments treating these patients. The registry included >130,000 events by the end of 2014, including 10,822 strokes and 4,227 TIAs registered in 2014. MAIN VARIABLES: The registry holds prospectively collected data on key processes...... of care, mainly covering the early phase after stroke, including data on time of delivery of the processes and the eligibility of the individual patients for each process. The data are used for assessing 18 process indicators reflecting recommendations in the national clinical guidelines for patients...

  13. Stroke mimic diagnoses presenting to a hyperacute stroke unit.

    Science.gov (United States)

    Dawson, Ang; Cloud, Geoffrey C; Pereira, Anthony C; Moynihan, Barry J

    2016-10-01

    Stroke services have been centralised in several countries in recent years. Diagnosing acute stroke is challenging and a high proportion of patients admitted to stroke units are diagnosed as a non-stroke condition (stroke mimics). This study aims to describe the stroke mimic patient group, including their impact on stroke services. We analysed routine clinical data from 2,305 consecutive admissions to a stroke unit at St George's Hospital, London. Mimic groupings were derived from 335 individual codes into 17 groupings. From 2,305 admissions, 555 stroke mimic diagnoses were identified (24.2%) and 72% of stroke mimics had at least one stroke risk factor. Common mimic diagnoses were headache, seizure and syncope. Medically unexplained symptoms and decompensation of underlying conditions were also common. Median length of stay was 1 day; a diagnosis of dementia (p=0.028) or needing MRI (p=0.006) was associated with a longer stay. Despite emergency department assessment by specialist clinicians and computed tomography brain, one in four suspected stroke patients admitted to hospital had a non-stroke diagnosis. Stroke mimics represent a heterogeneous patient group with significant impacts on stroke services. Co-location of stroke and acute neurology services may offer advantages where service reorganisation is being considered. © Royal College of Physicians 2016. All rights reserved.

  14. Post-stroke depression among stroke survivors attending two ...

    African Journals Online (AJOL)

    Background: The burden of stroke worldwide is increasing rapidly. There is paucity of data on post-stroke depression (PSD) among stroke survivors in Uganda, despite the high prevalence of PSD reported elsewhere. Methods: In a cross-sectional study, we assessed adult participants with confirmed first stroke with a ...

  15. Perception of stroke among patients with stroke | Ajayi | Nigerian ...

    African Journals Online (AJOL)

    The perception of patients to stroke is variable. The aim of this study was to determine the perception of stroke among stroke patients. The study was carried out between January 2004 - December 2004 on all the patients presenting with features of stroke at the Federal Medical Center Ido, Nigeria. Data were collected by ...

  16. Practical Statistics

    CERN Document Server

    Lyons, L.

    2016-01-01

    Accelerators and detectors are expensive, both in terms of money and human effort. It is thus important to invest effort in performing a good statistical anal- ysis of the data, in order to extract the best information from it. This series of five lectures deals with practical aspects of statistical issues that arise in typical High Energy Physics analyses.

  17. Cerebrorenal interaction and stroke.

    Science.gov (United States)

    Toyoda, Kazunori

    2013-01-01

    Beyond the original meaning of chronic kidney disease (CKD) as high-risk state for future dialysis, CKD is now known as an established risk factor for cardiovascular diseases. Stroke is a major player of cardiovascular disease and has deep two-way relationships with CKD. CKD is an evident risk factor for stroke. Meta-analyses of cohort studies and trials indicate that proteinuria/albuminuria increases the risk of stroke by 71-92%, and reduced glomerular filtration rate increases the risk by 43%. In addition, CKD has a strong relationship with subclinical brain damage including white matter changes, microbleeds, cognitive impairment, and carotid atherosclerosis. CKD is prevalent in acute stroke patients; patients with estimated glomerular filtration rate stroke patients and 39% of total intracerebral hemorrhage patients in our institute. Acute and chronic management of stroke are influenced by CKD. Therapeutic effects of several antithrombotic and thrombolytic agents, including recently-developed novel oral anticoagulants, are affected by renal function. Moreover, reduced glomerular filtration rate is independently associated with increased 1- and 10-year mortalities in the end. Stroke also has deep relationships with end-stage kidney disease. Stroke occurs much more commonly in dialysis patients than general population or CKD patients without need for dialysis. The triggers of ischemic and hemorrhagic stroke in patients with end-stage kidney disease include special characteristics unique to dialysis, such as drastic hemodynamic change, dialysate and anticoagulants, and vascular calcification. As cohorts of dialysis patients become older, more hypertensive, and more diabetic than before, stroke become more prevalent and more serious events in dialysis clinics. Now, clinicians should have much interest in the association between CKD and cerebrovascular diseases, so-called the cerebro-renal interaction. Copyright © 2013 S. Karger AG, Basel.

  18. Reversible Statistics

    DEFF Research Database (Denmark)

    Tryggestad, Kjell

    2004-01-01

    The study aims is to describe how the inclusion and exclusion of materials and calculative devices construct the boundaries and distinctions between statistical facts and artifacts in economics. My methodological approach is inspired by John Graunt's (1667) Political arithmetic and more recent work...... within constructivism and the field of Science and Technology Studies (STS). The result of this approach is here termed reversible statistics, reconstructing the findings of a statistical study within economics in three different ways. It is argued that all three accounts are quite normal, albeit...... by accounting for the significance of the materials and the equipment that enters into the production of statistics. Key words: Reversible statistics, diverse materials, constructivism, economics, science, and technology....

  19. Third European Stroke Science Workshop

    NARCIS (Netherlands)

    Dichgans, Martin; Planas, Anna M.; Biessels, Geert Jan|info:eu-repo/dai/nl/165576367; van der Worp, Bart|info:eu-repo/dai/nl/189855010; Sudlow, Cathie; Norrving, B.; Lees, Kennedy; Mattle, Heinrich P.

    2016-01-01

    Lake Eibsee, Garmisch-Partenkirchen, November 19 to 21, 2015: The European Stroke Organization convened >120 stroke experts from 27 countries to discuss latest results and hot topics in clinical, translational, and basic stroke research. Since its inception in 2011, the European Stroke Science

  20. Statistics Clinic

    Science.gov (United States)

    Feiveson, Alan H.; Foy, Millennia; Ploutz-Snyder, Robert; Fiedler, James

    2014-01-01

    Do you have elevated p-values? Is the data analysis process getting you down? Do you experience anxiety when you need to respond to criticism of statistical methods in your manuscript? You may be suffering from Insufficient Statistical Support Syndrome (ISSS). For symptomatic relief of ISSS, come for a free consultation with JSC biostatisticians at our help desk during the poster sessions at the HRP Investigators Workshop. Get answers to common questions about sample size, missing data, multiple testing, when to trust the results of your analyses and more. Side effects may include sudden loss of statistics anxiety, improved interpretation of your data, and increased confidence in your results.

  1. Statistical Physics

    CERN Document Server

    Wannier, Gregory Hugh

    1966-01-01

    Until recently, the field of statistical physics was traditionally taught as three separate subjects: thermodynamics, statistical mechanics, and kinetic theory. This text, a forerunner in its field and now a classic, was the first to recognize the outdated reasons for their separation and to combine the essentials of the three subjects into one unified presentation of thermal physics. It has been widely adopted in graduate and advanced undergraduate courses, and is recommended throughout the field as an indispensable aid to the independent study and research of statistical physics.Designed for

  2. Semiconductor statistics

    CERN Document Server

    Blakemore, J S

    1962-01-01

    Semiconductor Statistics presents statistics aimed at complementing existing books on the relationships between carrier densities and transport effects. The book is divided into two parts. Part I provides introductory material on the electron theory of solids, and then discusses carrier statistics for semiconductors in thermal equilibrium. Of course a solid cannot be in true thermodynamic equilibrium if any electrical current is passed; but when currents are reasonably small the distribution function is but little perturbed, and the carrier distribution for such a """"quasi-equilibrium"""" co

  3. SOCR Analyses - an Instructional Java Web-based Statistical Analysis Toolkit.

    Science.gov (United States)

    Chu, Annie; Cui, Jenny; Dinov, Ivo D

    2009-03-01

    The Statistical Online Computational Resource (SOCR) designs web-based tools for educational use in a variety of undergraduate courses (Dinov 2006). Several studies have demonstrated that these resources significantly improve students' motivation and learning experiences (Dinov et al. 2008). SOCR Analyses is a new component that concentrates on data modeling and analysis using parametric and non-parametric techniques supported with graphical model diagnostics. Currently implemented analyses include commonly used models in undergraduate statistics courses like linear models (Simple Linear Regression, Multiple Linear Regression, One-Way and Two-Way ANOVA). In addition, we implemented tests for sample comparisons, such as t-test in the parametric category; and Wilcoxon rank sum test, Kruskal-Wallis test, Friedman's test, in the non-parametric category. SOCR Analyses also include several hypothesis test models, such as Contingency tables, Friedman's test and Fisher's exact test.The code itself is open source (http://socr.googlecode.com/), hoping to contribute to the efforts of the statistical computing community. The code includes functionality for each specific analysis model and it has general utilities that can be applied in various statistical computing tasks. For example, concrete methods with API (Application Programming Interface) have been implemented in statistical summary, least square solutions of general linear models, rank calculations, etc. HTML interfaces, tutorials, source code, activities, and data are freely available via the web (www.SOCR.ucla.edu). Code examples for developers and demos for educators are provided on the SOCR Wiki website.In this article, the pedagogical utilization of the SOCR Analyses is discussed, as well as the underlying design framework. As the SOCR project is on-going and more functions and tools are being added to it, these resources are constantly improved. The reader is strongly encouraged to check the SOCR site for most

  4. Dietary fibre intake and risk of ischaemic and haemorrhagic stroke in the UK Women’s Cohort Study

    OpenAIRE

    Threapleton, DE; Burley, VJ; Greenwood, DC; Cade, JE

    2014-01-01

    BACKGROUND: Stroke risk is modifiable through many risk factors, one being healthy dietary habits. Fibre intake was associated with a reduced stroke risk in recent meta-analyses; however, data were contributed by relatively few studies, and few examined different stroke types. METHODS: A total of 27 373 disease-free women were followed up for 14.4 years. Diet was assessed with a 217-item food frequency questionnaire and stroke cases were identified using English Hospital Episode Statistics an...

  5. Dizziness in stroke

    Directory of Open Access Journals (Sweden)

    M. V. Zamergrad

    2015-01-01

    Full Text Available Differential diagnosis of new-onset acute vestibular vertigo is chiefly made between vestibular neuronitis and stroke. Dizziness in stroke is usually accompanied by other focal neurological symptoms of brainstem and cerebellar involvement. However, stroke may appear as isolated vestibular vertigo in some cases. An analysis of history data and the results of neurovestibular examination and brain magnetic resonance imaging allows stroke to be diagnosed in patients with acute isolated dizziness. The treatment of patients with stroke-induced dizziness involves a wide range of medications for the reduction of the degree of dizziness and unsteadiness and for the secondary prevention of stroke. Vestibular rehabilitation is an important component of treatment. The paper describes an observation of a patient with poorly controlled hypertension, who developed new-onset acute systemic dizziness. Vestibular neuronitis might be presumed to be a peripheral cause of vestibular disorders, by taking into account the absence of additional obvious neurological symptoms (such as pareses, defective sensation, diplopia, etc. and the nature of nystagmus. However, intention tremor in fingernose and heel-knee tests on the left side, a negative Halmagyi test, and results of Romberg’s test could suggest that stroke was a cause ofdizziness.

  6. Glucose and lipid assessment in patients with acute stroke.

    Science.gov (United States)

    Ogbera, Anthonia O; Oshinaike, Olajumoke O; Dada, Olusola; Brodie-Mends, Ayodeji; Ekpebegh, Chukwuma

    2014-01-01

    Stroke is a major health issue in Nigeria and it is also a common cause of emergency admissions. Stroke often results in increased morbidity, mortality and reduced quality of life in people thus affected. The risk factors for stroke include metabolic abnormalities such as dyslipidaemia and diabetes mellitus (DM). The stress of an acute stroke may present with hyperglycaemia and in persons without a prior history of DM, may be a pointer to stress hyperglycaemia or undiagnosed DM. This was a cross sectional study carried out over a period of one year in a teaching hospital in Lagos, Nigeria. Patients with acute stroke admitted to the hospital within three days of the episode of stroke and who met other inclusion criteria for the Study were consecutively recruited. Clinically relevant data was documented and biochemical assessments were carried out within three days of hospitalization. Tests for lipid profile, glycosylated haemoglobin(HbA1c), and blood glucose at presentation were carried out. The presence of past history of DM, undiagnosed DM, stress hyperglycaemia and abnormal lipid profile were noted. Students t test and Chi square were the statistical tests employed. A total of 137 persons with stroke were recruited of which 107 (76%) met the defining criteria for ischaemic stroke. The mean age and age range of the Study subjects were 62.2 (11.7) and 26-89 years respectively. The Study subjects were classified according to their glycaemic status into the following categories viz; stress hyperglycaemia, euglycaemia, DM and previously undiagnosed DM. Stress hyperglycaemia occurred commonly in the fifth decade of life and its incidence was comparable between those with cerebral and haemorrhagic stroke. The commonly occurring lipid abnormalities were elevated LDL-C and low HDL. The detection of abnormal metabolic milieu is a window of opportunity for aggressive management in persons with stroke as this will improve outcome. Routine screening for hyperglycaemia in

  7. Risk-adjusted hospital mortality rates for stroke: evidence from the Australian Stroke Clinical Registry (AuSCR).

    Science.gov (United States)

    Cadilhac, Dominique A; Kilkenny, Monique F; Levi, Christopher R; Lannin, Natasha A; Thrift, Amanda G; Kim, Joosup; Grabsch, Brenda; Churilov, Leonid; Dewey, Helen M; Hill, Kelvin; Faux, Steven G; Grimley, Rohan; Castley, Helen; Hand, Peter J; Wong, Andrew; Herkes, Geoffrey K; Gill, Melissa; Crompton, Douglas; Middleton, Sandy; Donnan, Geoffrey A; Anderson, Craig S

    2017-05-01

    Hospital data used to assess regional variability in disease management and outcomes, including mortality, lack information on disease severity. We describe variance between hospitals in 30-day risk-adjusted mortality rates (RAMRs) for stroke, comparing models that include or exclude stroke severity as a covariate. Cohort design linking Australian Stroke Clinical Registry data with national death registrations. Multivariable models using recommended statistical methods for calculating 30-day RAMRs for hospitals, adjusted for demographic factors, ability to walk on admission, stroke type, and stroke recurrence. Australian hospitals providing at least 200 episodes of acute stroke care, 2009-2014. Hospital RAMRs estimated by different models. Changes in hospital rank order and funnel plots were used to explore variation in hospital-specific 30-day RAMRs; that is, RAMRs more than three standard deviations from the mean. In the 28 hospitals reporting at least 200 episodes of care, there were 16 218 episodes (15 951 patients; median age, 77 years; women, 46%; ischaemic strokes, 79%). RAMRs from models not including stroke severity as a variable ranged between 8% and 20%; RAMRs from models with the best fit, which included ability to walk and stroke recurrence as variables, ranged between 9% and 21%. The rank order of hospitals changed according to the covariates included in the models, particularly for those hospitals with the highest RAMRs. Funnel plots identified significant deviation from the mean overall RAMR for two hospitals, including one with borderline excess mortality. Hospital stroke mortality rates and hospital performance ranking may vary widely according to the covariates included in the statistical analysis.

  8. Multiparametric statistics

    CERN Document Server

    Serdobolskii, Vadim Ivanovich

    2007-01-01

    This monograph presents mathematical theory of statistical models described by the essentially large number of unknown parameters, comparable with sample size but can also be much larger. In this meaning, the proposed theory can be called "essentially multiparametric". It is developed on the basis of the Kolmogorov asymptotic approach in which sample size increases along with the number of unknown parameters.This theory opens a way for solution of central problems of multivariate statistics, which up until now have not been solved. Traditional statistical methods based on the idea of an infinite sampling often break down in the solution of real problems, and, dependent on data, can be inefficient, unstable and even not applicable. In this situation, practical statisticians are forced to use various heuristic methods in the hope the will find a satisfactory solution.Mathematical theory developed in this book presents a regular technique for implementing new, more efficient versions of statistical procedures. ...

  9. Accident Statistics

    Data.gov (United States)

    Department of Homeland Security — Accident statistics available on the Coast Guard’s website by state, year, and one variable to obtain tables and/or graphs. Data from reports has been loaded for...

  10. CMS Statistics

    Data.gov (United States)

    U.S. Department of Health & Human Services — The CMS Center for Strategic Planning produces an annual CMS Statistics reference booklet that provides a quick reference for summary information about health...

  11. Reversible Statistics

    DEFF Research Database (Denmark)

    Tryggestad, Kjell

    2004-01-01

    The study aims is to describe how the inclusion and exclusion of materials and calculative devices construct the boundaries and distinctions between statistical facts and artifacts in economics. My methodological approach is inspired by John Graunt's (1667) Political arithmetic and more recent work...... within constructivism and the field of Science and Technology Studies (STS). The result of this approach is here termed reversible statistics, reconstructing the findings of a statistical study within economics in three different ways. It is argued that all three accounts are quite normal, albeit...... in different ways. The presence and absence of diverse materials, both natural and political, is what distinguishes them from each other. Arguments are presented for a more symmetric relation between the scientific statistical text and the reader. I will argue that a more symmetric relation can be achieved...

  12. Image Statistics

    Energy Technology Data Exchange (ETDEWEB)

    Wendelberger, Laura Jean [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-08-08

    In large datasets, it is time consuming or even impossible to pick out interesting images. Our proposed solution is to find statistics to quantify the information in each image and use those to identify and pick out images of interest.

  13. Vital statistics

    CERN Document Server

    MacKenzie, Dana

    2004-01-01

    The drawbacks of using 19th-century mathematics in physics and astronomy are illustrated. To continue with the expansion of the knowledge about the cosmos, the scientists will have to come in terms with modern statistics. Some researchers have deliberately started importing techniques that are used in medical research. However, the physicists need to identify the brand of statistics that will be suitable for them, and make a choice between the Bayesian and the frequentists approach. (Edited abstract).

  14. Practical Statistics

    OpenAIRE

    Lyons, L.

    2017-01-01

    Accelerators and detectors are expensive, both in terms of money and human effort. It is thus important to invest effort in performing a good statistical anal- ysis of the data, in order to extract the best information from it. This series of five lectures deals with practical aspects of statistical issues that arise in typical High Energy Physics analyses. Accelerators and detectors are expensive, both in terms of money and human effort. It is thus important to invest effort in performing...

  15. Incorporating Stroke Severity Into Hospital Measures of 30-Day Mortality After Ischemic Stroke Hospitalization.

    Science.gov (United States)

    Schwartz, Jennifer; Wang, Yongfei; Qin, Li; Schwamm, Lee H; Fonarow, Gregg C; Cormier, Nicole; Dorsey, Karen; McNamara, Robert L; Suter, Lisa G; Krumholz, Harlan M; Bernheim, Susannah M

    2017-11-01

    The Centers for Medicare & Medicaid Services publicly reports a hospital-level stroke mortality measure that lacks stroke severity risk adjustment. Our objective was to describe novel measures of stroke mortality suitable for public reporting that incorporate stroke severity into risk adjustment. We linked data from the American Heart Association/American Stroke Association Get With The Guidelines-Stroke registry with Medicare fee-for-service claims data to develop the measures. We used logistic regression for variable selection in risk model development. We developed 3 risk-standardized mortality models for patients with acute ischemic stroke, all of which include the National Institutes of Health Stroke Scale score: one that includes other risk variables derived only from claims data (claims model); one that includes other risk variables derived from claims and clinical variables that could be obtained from electronic health record data (hybrid model); and one that includes other risk variables that could be derived only from electronic health record data (electronic health record model). The cohort used to develop and validate the risk models consisted of 188 975 hospital admissions at 1511 hospitals. The claims, hybrid, and electronic health record risk models included 20, 21, and 9 risk-adjustment variables, respectively; the C statistics were 0.81, 0.82, and 0.79, respectively (as compared with the current publicly reported model C statistic of 0.75); the risk-standardized mortality rates ranged from 10.7% to 19.0%, 10.7% to 19.1%, and 10.8% to 20.3%, respectively; the median risk-standardized mortality rate was 14.5% for all measures; and the odds of mortality for a high-mortality hospital (+1 SD) were 1.51, 1.52, and 1.52 times those for a low-mortality hospital (-1 SD), respectively. We developed 3 quality measures that demonstrate better discrimination than the Centers for Medicare & Medicaid Services' existing stroke mortality measure, adjust for

  16. Explicit memory and implicit memory in occipital lobe stroke patients.

    Science.gov (United States)

    Gong, Liang; Wang, JiHua; Feng, Lei; Wang, MeiHong; Li, Xiu; Hu, JiaYun; Wang, Kai

    2015-03-01

    Occipital stroke patients mainly showed cortical blindness and unilateral vision loss; memory is generally reserved. Recent reports from neuroimaging show the occipital lobe may be involved in the processing of implicit memory (IM), especially the perception type of IM processing. In this study, we explored the explicit memory (EM) and IM damage in occipital lobe stroke patients. A total of 25 occipital strokes and 29 years of age, educational level equivalent healthy controls (HCs), evaluated by using immediate recall, delayed recall, recognition for EM tasks, picture identification, and category exemplar generation for IM tasks. There was no significant difference between occipital stroke patients and HCs in EM tasks and category exemplar generation task. In the picture identification task, occipital lobe stroke group score was poorer than HC group, the results were statistically significant, but in the pictures identify rate, occipital stroke patients and normal control group had no significant difference. The occipital stroke patients may have IM damage, primarily damage the perception type of IM priming effects, which was unrelated with their cortical blindness. Copyright © 2015 National Stroke Association. Published by Elsevier Inc. All rights reserved.

  17. Clinical neurogenetics: stroke.

    Science.gov (United States)

    Rost, Natalia S

    2013-11-01

    Understanding the genetic architecture of cerebrovascular disease holds promise of novel stroke prevention strategies and therapeutics that are both safe and effective. Apart from a few single-gene disorders associated with cerebral ischemia or intracerebral hemorrhage, stroke is a complex genetic phenotype that requires careful ascertainment and robust association testing for discovery and validation analyses. The recently uncovered shared genetic contribution between clinically manifest stroke syndromes and closely related intermediate cerebrovascular phenotypes offers effective and efficient approaches to complex trait analysis. Copyright © 2013 Elsevier Inc. All rights reserved.

  18. Cost of stroke

    DEFF Research Database (Denmark)

    Jennum, Poul; Iversen, Helle K; Ibsen, Rikke

    2015-01-01

    . The attributable cost of direct net health care costs after the stroke (general practitioner services, hospital services, and medication) and indirect costs (loss of labor market income) were €10,720, €8,205 and €7,377 for patients, and €989, €1,544 and €1.645 for their partners, over and above that of controls......BACKGROUND: To estimate the direct and indirect costs of stroke in patients and their partners. DESCRIPTION: Direct and indirect costs were calculated using records from the Danish National Patient Registry from 93,047 ischemic, 26,012 hemorrhagic and 128,824 unspecified stroke patients...

  19. Determinan Penyakit Stroke

    Directory of Open Access Journals (Sweden)

    Woro Riyadina

    2013-02-01

    Full Text Available Penyakit stroke merupakan penyebab kematian dan kecacatan kronik yang paling tinggi pada kelompok umur diatas usia 45 tahun terbanyak di Indonesia. Tujuan penelitian ini untuk mengidentifikasi determinan utama yang berhubungan dengan penyakit stroke pada masyarakat di kelurahan Kebon Kalapa Bogor. Analisis lanjut terhadap 1.912 responden subset baseline data penelitian “Studi Kohort Faktor Risiko Penyakit Tidak Menular” Data dikumpulkan dengan metode wawancara pada penduduk tetap di kelurahan Kebon Kalapa, Kecamatan Bogor Tengah, Bogor tahun 2012. Diagnosis stroke berdasarkan anamnesis dan pemeriksaan dokter spesialis syaraf. Variabel independen meliputi karakteristik sosiodemografi, status kesehatan dan perilaku berisiko. Data dianalisis dengan uji regresi logistik ganda. Penyakit stroke ditemukan pada 49 (2,6% orang. Determinan utama stroke meliputi hipertensi (OR = 4,20; IK 95% = 2,20 – 8,03, penyakit jantung koroner (OR = 2,74; IK 95% = 1,51 – 4,99, diabetes melitus (OR = 2,89; IK 95% = 1,47 – 5,64, dan status ekonomi miskin (OR = 1,83 ; IK 95% = 1,03 – 3,33. Pencegahan penyakit stroke dilakukan dengan peningkatan edukasi (kampanye/penyuluhan melalui pengendalian faktor risiko utama yaitu hipertensi dan pencegahan terjadinya penyakit degeneratif lain yaitu penyakit jantung koroner dan diabetes melitus. Stroke disease is the leading cause of death and chronic disabi lity in most over the age of 45 years in Indonesia. The aim of study was to identify the major determinants of stroke disease in Kebon Kalapa community in Bogor. A deep analyze was conducted in 1.912 respondents based on the subset of baseline data “Risk Factors Cohort Study of Non Communicable Diseases.” Data was collected by interviews on Kebon Kalapa community, Bogor in 2012. Stroke diagnosis was determined by anamnesis and neu-rological examination with specialist. Independent variables were sociodemographic characteristics, health status and risk behavior

  20. The Migraine?Stroke Connection

    OpenAIRE

    Lee, Mi Ji; Lee, Chungbin; Chung, Chin-Sang

    2016-01-01

    Migraine and stroke are common neurovascular disorders which share underlying physiological processes. Increased risks of ischemic stroke, hemorrhagic stroke, and subclinical ischemic lesions have been consistently found in migraineurs. Three possible associations are suggested. One is that underlying pathophysiology of migraine can lead to ischemic stroke. Second, common comorbidities between migraine and stroke can be present. Lastly, some syndromes can manifest with both migraine-like head...

  1. Dietary fibre intake and risk of ischaemic and haemorrhagic stroke in the UK Women's Cohort Study.

    Science.gov (United States)

    Threapleton, D E; Burley, V J; Greenwood, D C; Cade, J E

    2015-04-01

    Stroke risk is modifiable through many risk factors, one being healthy dietary habits. Fibre intake was associated with a reduced stroke risk in recent meta-analyses; however, data were contributed by relatively few studies, and few examined different stroke types. A total of 27,373 disease-free women were followed up for 14.4 years. Diet was assessed with a 217-item food frequency questionnaire and stroke cases were identified using English Hospital Episode Statistics and mortality records. Survival analysis was applied to assess the risk of total, ischaemic or haemorrhagic stroke in relation to fibre intake. A total of 135 haemorrhagic and 184 ischaemic stroke cases were identified in addition to 138 cases where the stroke type was unknown or not recorded. Greater intake of total fibre, higher fibre density and greater soluble fibre, insoluble fibre and fibre from cereals were associated with a significantly lower risk for total stroke. For total stroke, the hazard ratio per 6 g/day total fibre intake was 0.89 (95% confidence intervals: 0.81-0.99). Different findings were observed for haemorrhagic and ischaemic stroke in healthy-weight or overweight women. Total fibre, insoluble fibre and cereal fibre were inversely associated with haemorrhagic stroke risk in overweight/obese participants, and in healthy-weight women greater cereal fibre was associated with a lower ischaemic stroke risk. In non-hypertensive women, higher fibre density was associated with lower ischaemic stroke risk. Greater total fibre and fibre from cereals are associated with a lower stroke risk, and associations were more consistent with ischaemic stroke. The different observations by stroke type, body mass index group or hypertensive status indicates potentially different mechanisms.

  2. Stroke - risk factors

    Science.gov (United States)

    ... Brain cells can die, causing lasting damage. Risk factors are things that increase your chance of getting ... disease or condition. This article discusses the risk factors for stroke and things you can do to ...

  3. Post-Stroke Rehabilitation

    Science.gov (United States)

    ... negotiate the provision of reasonable accommodations in the workplace. When can a stroke patient begin rehabilitation? Rehabilitation ... at home gives people the advantage of practicing skills and developing compensatory strategies in the context of ...

  4. A Stroke of Language

    Science.gov (United States)

    Blaisdell, Bob

    2011-01-01

    The author reflects on foreign-language learning by his EFL students as well as his own foreign-language learning. He concludes by musing on the possible and fantastical devastation on language-ability wrought by strokes.

  5. Epilepsy after stroke

    DEFF Research Database (Denmark)

    Olsen, T S; Høgenhaven, H; Thage, O

    1987-01-01

    Development of epilepsy was studied prospectively in a group of 77 consecutive stroke patients. Included were stroke patients less than 75 years old admitted within the first 3 days after the stroke. Excluded were patients with subarachnoid hemorrhage, vertebrobasilar stroke, and patients...... with other severe diseases. Cerebral angiography, CT, and EEG were performed in all patients. The patients were followed clinically for 2 to 4 years. Seven patients (9%) developed epilepsy. Of 23 patients with lesions involving the cortex, 6 (26%) developed epilepsy. Of 54 patients in whom the cortex...... was not involved, only 1 (2%) developed epilepsy. Patients with persisting paresis and cortical involvement seem to be at particularly high risk of developing epilepsy, as 50% of such patients (6 of 12) developed the disease....

  6. The "Know Stroke" Campaign

    Science.gov (United States)

    ... Issue Past Issues Special Section The "Know Stroke" Campaign Past Issues / Summer 2007 Table of Contents For ... Javascript on. NINDS is conducting a public awareness campaign across the United States to educate people about ...

  7. Statistical mechanics

    CERN Document Server

    Schwabl, Franz

    2006-01-01

    The completely revised new edition of the classical book on Statistical Mechanics covers the basic concepts of equilibrium and non-equilibrium statistical physics. In addition to a deductive approach to equilibrium statistics and thermodynamics based on a single hypothesis - the form of the microcanonical density matrix - this book treats the most important elements of non-equilibrium phenomena. Intermediate calculations are presented in complete detail. Problems at the end of each chapter help students to consolidate their understanding of the material. Beyond the fundamentals, this text demonstrates the breadth of the field and its great variety of applications. Modern areas such as renormalization group theory, percolation, stochastic equations of motion and their applications to critical dynamics, kinetic theories, as well as fundamental considerations of irreversibility, are discussed. The text will be useful for advanced students of physics and other natural sciences; a basic knowledge of quantum mechan...

  8. Statistical mechanics

    CERN Document Server

    Jana, Madhusudan

    2015-01-01

    Statistical mechanics is self sufficient, written in a lucid manner, keeping in mind the exam system of the universities. Need of study this subject and its relation to Thermodynamics is discussed in detail. Starting from Liouville theorem gradually, the Statistical Mechanics is developed thoroughly. All three types of Statistical distribution functions are derived separately with their periphery of applications and limitations. Non-interacting ideal Bose gas and Fermi gas are discussed thoroughly. Properties of Liquid He-II and the corresponding models have been depicted. White dwarfs and condensed matter physics, transport phenomenon - thermal and electrical conductivity, Hall effect, Magneto resistance, viscosity, diffusion, etc. are discussed. Basic understanding of Ising model is given to explain the phase transition. The book ends with a detailed coverage to the method of ensembles (namely Microcanonical, canonical and grand canonical) and their applications. Various numerical and conceptual problems ar...

  9. Statistical inference

    CERN Document Server

    Rohatgi, Vijay K

    2003-01-01

    Unified treatment of probability and statistics examines and analyzes the relationship between the two fields, exploring inferential issues. Numerous problems, examples, and diagrams--some with solutions--plus clear-cut, highlighted summaries of results. Advanced undergraduate to graduate level. Contents: 1. Introduction. 2. Probability Model. 3. Probability Distributions. 4. Introduction to Statistical Inference. 5. More on Mathematical Expectation. 6. Some Discrete Models. 7. Some Continuous Models. 8. Functions of Random Variables and Random Vectors. 9. Large-Sample Theory. 10. General Meth

  10. Statistical mechanics

    CERN Document Server

    Davidson, Norman

    2003-01-01

    Clear and readable, this fine text assists students in achieving a grasp of the techniques and limitations of statistical mechanics. The treatment follows a logical progression from elementary to advanced theories, with careful attention to detail and mathematical development, and is sufficiently rigorous for introductory or intermediate graduate courses.Beginning with a study of the statistical mechanics of ideal gases and other systems of non-interacting particles, the text develops the theory in detail and applies it to the study of chemical equilibrium and the calculation of the thermody

  11. AP statistics

    CERN Document Server

    Levine-Wissing, Robin

    2012-01-01

    All Access for the AP® Statistics Exam Book + Web + Mobile Everything you need to prepare for the Advanced Placement® exam, in a study system built around you! There are many different ways to prepare for an Advanced Placement® exam. What's best for you depends on how much time you have to study and how comfortable you are with the subject matter. To score your highest, you need a system that can be customized to fit you: your schedule, your learning style, and your current level of knowledge. This book, and the online tools that come with it, will help you personalize your AP® Statistics prep

  12. Statistical Physics

    CERN Document Server

    Mandl, Franz

    1988-01-01

    The Manchester Physics Series General Editors: D. J. Sandiford; F. Mandl; A. C. Phillips Department of Physics and Astronomy, University of Manchester Properties of Matter B. H. Flowers and E. Mendoza Optics Second Edition F. G. Smith and J. H. Thomson Statistical Physics Second Edition E. Mandl Electromagnetism Second Edition I. S. Grant and W. R. Phillips Statistics R. J. Barlow Solid State Physics Second Edition J. R. Hook and H. E. Hall Quantum Mechanics F. Mandl Particle Physics Second Edition B. R. Martin and G. Shaw The Physics of Stars Second Edition A. C. Phillips Computing for Scient

  13. Telestroke in stroke survivors.

    Science.gov (United States)

    Joubert, Jacques; Joubert, Lynette B; de Bustos, Elizabeth Medeiros; Ware, Dallas; Jackson, David; Harrison, Terrence; Cadilhac, Dominique

    2009-01-01

    Stroke is a high-frequency disorder placing a significant burden on the health care systems, being the foremost cause of complex chronic disability in adults. Devising systems that can enhance the prevention of stroke recurrence is an important priority and challenge in both the developed and the developing world. The potential for recurrent stroke can be substantially reduced by effective management of vascular risk factors. Telestroke is a tool with potential application to improve risk management of stroke survivors. Lack of acknowledgment of existing practices as well as lack of awareness of potential financial barriers to diffusion of telestroke can lead to limited implementation. Telestroke offers service providers the opportunity to access large numbers of stroke survivors targeting secondary prevention. The ideal 'telestroke model' provides service support, education for the patient and caregiver, as well as integration of specialist and primary care services. Effective use of technological advances, with adequate recognition of the importance of human interaction in the long-term management of a largely elderly population of stroke survivors is challenging but possible. Telestroke should be systems- and not technology-driven. Barriers in the implementation of telestroke have been identified as insufficient planning of IT infrastructure, lack of long-term vision for sustainability, a lack of contextual perspective as well as poor communication across domains. Future telestroke models should provide effective action in an integrated model of care recognizing and involving all existing players and practices. (c) 2009 S. Karger AG, Basel.

  14. Autopsy approach to stroke.

    Science.gov (United States)

    Love, Seth

    2011-02-01

    Stroke is a major cause of morbidity and mortality but the brain and other relevant tissues are often examined only cursorily when stroke patients come to autopsy. The pathological findings and clinical implications vary according to the type of stroke and its location and cause. Large ischaemic strokes are usually associated with atherosclerosis of extracranial or major intracranial arteries but can be caused by dissection. Most small cerebral infarcts are caused by arteriosclerosis or, in the elderly, cerebral amyloid angiopathy (CAA). However, vasculitides and coagulopathies can cause a range of different patterns of ischaemic (and, occasionally, haemorrhagic) stroke. Global brain ischaemia, caused by severe hypotension or raised intracranial pressure, produces damage that is accentuated in certain regions and neuronal populations and may be confused with hypoglycaemic injury. The main cause of subarachnoid haemorrhage is a ruptured berry aneurysm but CAA, arteriovenous malformations and infective aneurysms are occasionally responsible. These can also cause parenchymal brain haemorrhage, although this most often complicates hypertensive small vessel disease. Sometimes the haemorrhage arises from a neoplasm. Performing an adequate autopsy in stroke requires proper preparation, awareness of the likely pathological processes, familiarity with intracranial vascular anatomy, careful gross examination and dissection, and appropriate use of histology. © 2010 Blackwell Publishing Limited.

  15. Post-stroke dyskinesias

    Directory of Open Access Journals (Sweden)

    Nakawah MO

    2016-11-01

    Full Text Available Mohammad Obadah Nakawah, Eugene C Lai Stanely H. Appel Department of Neurology, Houston Methodist Neurological Institute, Houston, TX, USA Abstract: Strokes, whether ischemic or hemorrhagic, are among the most common causes of secondary movement disorders in elderly patients. Stroke-related (vascular movement disorders, however, are uncommon complications of this relatively common disease. The spectrum of post-stroke movement disorders is broad and includes both hypo- and hyperkinetic syndromes. Post-stroke dyskinesias are involuntary hyperkinetic movements arising from cerebrovascular insults and often present with mixed phenotypes of hyperkinesia which can sometimes be difficult to classify. Nevertheless, identification of the most relevant motor phenotype, whenever possible, allows for a more specific phenomenological categorization of the dyskinesia and thus helps guide its treatment. Fortunately, post-stroke dyskinesias are usually self-limiting and resolve within 6 to 12 months of onset, but a short-term pharmacotherapy might sometimes be required for symptom control. Functional neurosurgical interventions targeting the motor thalamus or globus pallidus interna might be considered for patients with severe, disabling, and persistent dyskinesias (arbitrarily defined as duration longer than 12 months. Keywords: vascular dyskinesia, stroke, movement disorders

  16. Virtual reality for stroke rehabilitation.

    Science.gov (United States)

    Laver, Kate E; Lange, Belinda; George, Stacey; Deutsch, Judith E; Saposnik, Gustavo; Crotty, Maria

    2017-11-20

    number of randomised controlled trials, the evidence remains mostly low quality when rated using the GRADE system. Control groups usually received no intervention or therapy based on a standard-care approach. results were not statistically significant for upper limb function (standardised mean difference (SMD) 0.07, 95% confidence intervals (CI) -0.05 to 0.20, 22 studies, 1038 participants, low-quality evidence) when comparing virtual reality to conventional therapy. However, when virtual reality was used in addition to usual care (providing a higher dose of therapy for those in the intervention group) there was a statistically significant difference between groups (SMD 0.49, 0.21 to 0.77, 10 studies, 210 participants, low-quality evidence). when compared to conventional therapy approaches there were no statistically significant effects for gait speed or balance. Results were statistically significant for the activities of daily living (ADL) outcome (SMD 0.25, 95% CI 0.06 to 0.43, 10 studies, 466 participants, moderate-quality evidence); however, we were unable to pool results for cognitive function, participation restriction, or quality of life. Twenty-three studies reported that they monitored for adverse events; across these studies there were few adverse events and those reported were relatively mild. We found evidence that the use of virtual reality and interactive video gaming was not more beneficial than conventional therapy approaches in improving upper limb function. Virtual reality may be beneficial in improving upper limb function and activities of daily living function when used as an adjunct to usual care (to increase overall therapy time). There was insufficient evidence to reach conclusions about the effect of virtual reality and interactive video gaming on gait speed, balance, participation, or quality of life. This review found that time since onset of stroke, severity of impairment, and the type of device (commercial or customised) were not strong

  17. Nursing care for stroke patients

    DEFF Research Database (Denmark)

    Tulek, Zeliha; Poulsen, Ingrid; Gillis, Katrin

    2018-01-01

    AIMS AND OBJECTIVES: To conduct a survey of the clinical nursing practice in European countries in accordance with the European Stroke Strategies (ESS) 2006, and to examine to what extent the ESS have been implemented in stroke care nursing in Europe. BACKGROUND: Stroke is a leading cause of death...... comprising 61 questions based on the ESS and scientific evidence in nursing practice was distributed to representatives of the European Association of Neuroscience Nurses, who sent the questionnaire to nurses active in stroke care. The questionnaire covered the following areas of stroke care: Organization...... of stroke services, Management of acute stroke and prevention including basic care and nursing, and Secondary prevention. RESULTS: Ninety-two nurses in stroke care in 11 European countries participated in the survey. Within the first 48 hours after stroke onset, 95% monitor patients regularly, 94% start...

  18. Improving public education about stroke.

    Science.gov (United States)

    Alberts, Mark J

    2012-09-01

    Stroke is a common and serious disease. Most studies have shown that basic public knowledge about what a stroke is, symptoms of a stroke, and the proper reaction to a stroke is quite deficient. The fact that a stroke affects cognitive, communicative, and motor functions may partially explain the poor reaction to acute stroke symptoms. Several educational studies, using diverse formats and messaging paradigms, have been shown to positively affect public knowledge of stroke symptoms. Such efforts have often used mass media public education campaigns with an emphasis on recognizing symptoms of an acute stroke. Some have been able to demonstrate an increase in the chance of patients (or by-standers) calling 911 and seeking emergency care. However, many programs were of brief duration, and their long-term benefits are uncertain. Continual educational efforts will be needed to improve stroke knowledge and increase the percentage of patients who seek emergency care. © 2012 New York Academy of Sciences.

  19. UPDATE ON THE GLOBAL BURDEN OF ISCHAEMIC AND HAEMORRHAGIC STROKE IN 1990–2013: THE GBD 2013 STUDY

    Science.gov (United States)

    Feigin, Valery L.; Krishnamurthi, Rita; Parmar, Priya; Norrving, Bo; Mensah, George A.; Bennett, Derrick A.; Barker-Collo, Suzanne; Moran, Andrew; Sacco, Ralph L.; Truelsen, Thomas; Davis, Stephen; Pandian, Jeyaraj Durai; Naghavi, Mohsen; Forouzanfar, Mohammad H.; Nguyen, Grant; Johnson, Catherine O.; Vos, Theo; Meretoja, Atte; Murray, Christopher; Roth, Gregory A.; Thrift, Amanda; Banerjee, Amitava; Kengne, Andre Pascal; Misganaw, Awoke; Kissela, Brett M.; Wolfe, Charles; Yu, Chuanhua; Anderson, Craig; Kim, Daniel; Rojas-Rueda, David; Tanne, David; Tirschwell, David Lawrence; Nand, Devina; Kazi, Dhruv S.; Pourmalek, Farshad; Catalá-López, Ferrán; Abd-Allah, Foad; Gankpé, Fortuné; deVeber, Gabrielle; Donnan, Geoffrey; Hankey, Graeme J.; Christensen, Hanne K.; Campos-Nonato, Ismael; Shiue, Ivy; Fernandes, Jefferson G.; Jonas, Jost B.; Sheth, Kevin; Kim, Yunjin; Dokova, Klara; Stroumpoulis, Konstantinos; Sposato, Luciano A.; Bahit, Maria Cecilia; Geleijnse, Johanna M.; Mackay, Mark T.; Mehndiratta, Man Mohan; Endres, Matthias; Giroud, Maurice; Brainin, Michael; Kravchenko, Michael; Piradov, Michael; Soljak, Michael; Liu, Ming; Connor, Myles; Venketasubramanian, Narayanaswamy; Bornstein, Natan; Shamalov, Nikolay; Roy, Nobhojit; Cabral, Norberto; Beauchamp, Norman J.; Lavados, Pablo M.; Jeemon, Panniyammakal; Lotufo, Paulo A.; Chowdhury, Rajiv; Sahathevan, Ramesh; Hamadeh, Randah R.; Malekzadeh, Reza; Gillium, Richard; Westerman, Ronny; Akinyemi, Rufus Olusola; Salman, Rustam Al-Shahi; Dharmaratne, Samath D.; Basu, Sanjay; Abera, Semaw Ferede; Kosen, Soewarta; Sampson, Uchechukwu K. A.; Caso, Valeria; Vlassov, Vasiliy; Melaku, Yohannes Adama; Kokubo, Yoshiohiro; Shinohara, Yukito; Varakin, Yuri; Wang, Wenzhi

    2015-01-01

    Background Global stroke epidemiology is changing rapidly. Although age-standardised rates of stroke mortality have decreased worldwide in the past two decades, the absolute numbers of people who have a stroke every year, live with the consequences of stroke, and die from their stroke are increasing. Regular updates on the current level of stroke burden are important for advancing our knowledge on stroke epidemiology and facilitate organization and planning of evidence-based stroke care. Objectives To estimate incidence, prevalence, mortality, disability-adjusted life-years (DALYs) and years lived with disability (YLDs), and their trends for ischaemic stroke (IS) and haemorrhagic stroke (HS) for 188 countries from 1990–2013. Methodology Stroke incidence, prevalence, mortality, DALYs and YLDs were estimated using all available data on mortality and stroke incidence, prevalence and excess mortality. Statistical models and country-level covariate data were employed and all rates were age-standardised to a global population. All estimated were produced with 95% uncertainty intervals (UI). Results In 2013, there were globally almost 25.7 million stroke survivors (71% with IS), 6.5 million deaths from stroke (51% died from IS), 113 million DALYs due to stroke (58% due to IS), and 10.3 million new strokes (67% IS). Over the 1990–2013 period, there was a significant increase in the absolute number of DALYs due to IS, and of deaths from IS and HS, survivors and incident events for both IS and HS. The preponderance of the burden of stroke continued to reside in developing countries, comprising 75.2% of deaths from stroke and 81.0% of stroke-related DALYs. Globally, the proportional contribution of stroke-related DALYs and deaths due to stroke compared to all diseases increased from 1990 (3.54% [95% UI 3.11–4.00%] and 9.66% [95% UI 8.47–10.70%]) to 2013 (4.62% [95% UI 4.01–5.30%] and 11.75% [95% UI 10.45–13.31%], respectively), but there was a diverging trend in

  20. Statistical Computing

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 4; Issue 10. Statistical Computing - Understanding Randomness and Random Numbers. Sudhakar Kunte. Series Article Volume 4 Issue 10 October 1999 pp 16-21. Fulltext. Click here to view fulltext PDF. Permanent link:

  1. Statistical thermodynamics

    CERN Document Server

    Schrödinger, Erwin

    1952-01-01

    Nobel Laureate's brilliant attempt to develop a simple, unified standard method of dealing with all cases of statistical thermodynamics - classical, quantum, Bose-Einstein, Fermi-Dirac, and more.The work also includes discussions of Nernst theorem, Planck's oscillator, fluctuations, the n-particle problem, problem of radiation, much more.

  2. Does Stroke Contribute to Racial Differences in Cognitive Decline?

    Science.gov (United States)

    Levine, Deborah A.; Kabeto, Mohammed; Langa, Kenneth M.; Lisabeth, Lynda D.; Rogers, Mary A.M.; Galecki, Andrzej T.

    2015-01-01

    Background and Purpose It is unknown whether blacks’ elevated risk of dementia is because of racial differences in acute stroke, the impact of stroke on cognitive health, or other factors. We investigated whether racial differences in cognitive decline are explained by differences in the frequency or impact of incident stroke between blacks and whites, controlling for baseline cognition. Methods Among 4908 black and white participants aged ≥65 years free of stroke and cognitive impairment in the nationally representative Health and Retirement Study with linked Medicare data (1998–2010), we examined longitudinal changes in global cognition (modified version of the Telephone Interview for Cognitive Status) by race, before and after adjusting for time-dependent incident stroke followed by a race-by-incident stroke interaction term, using linear mixed-effects models that included fixed effects of participant demographics, clinical factors, and cognition, and random effects for intercept and slope for time. Results We identified 34 of 453 (7.5%) blacks and 300 of 4455 (6.7%) whites with incident stroke over a mean (SD) of 4.1 (1.9) years of follow-up (P=0.53). Blacks had greater cognitive decline than whites (adjusted difference in modified version of the Telephone Interview for Cognitive Status score, 1.47 points; 95% confidence interval, 1.21 to 1.73 points). With further adjustment for cumulative incidence of stroke, the black–white difference in cognitive decline persisted. Incident stroke was associated with a decrease in global cognition (1.21 points; Pstroke on cognition did not statistically differ by race (P=0.52). Conclusions In this population-based cohort of older adults, incident stroke did not explain black–white differences in cognitive decline or impact cognition differently by race. PMID:25999389

  3. Relearning the Basics: Rehabilitation after a Stroke

    Science.gov (United States)

    ... of this page please turn Javascript on. Feature: Stroke Rehabilitation Relearning the Basics: Rehabilitation After a Stroke Past ... to help them recover successfully. What is post-stroke rehabilitation? Rehab helps stroke survivors relearn skills lost to ...

  4. The effects of temporary hyperglycemia on the prognosis of stroke in patients with acute ischaemıc stroke

    Directory of Open Access Journals (Sweden)

    Soner Kılıc

    2012-12-01

    Full Text Available OBJECTIVE: In this study, frequency of temporary hyperglycemia and effects of the hyperglycemia on the severity and prognosis of stroke were examined in patients with acute ischaemic stroke. MATERIAL and METHODS: One hundred patients, who applied for acute ischaemic stroke and met the inclusion criteria, were included in the study. Patients were diveded into three groups: normoglycemic, temporary hyperglycemic and diabetes mellitus (DM, according to the baseline blood glucose, fasting blood glucose, oral glucose tolerance test (OGTT test and HbA1c value. These groups’ National Institue of Stroke Scale (NIHSS, Fugl–Meyer (FM and Functional Independence Measure (FIM scores were measured at baseline and at the 3rd month of the follow up; then, these data were compared in terms of the severity and prognosis of stroke. In addition, according to the fasting blood glucose, hyperglycemic and normoglycemic patients becoming permanent diabetics were evaluated. ANOVA, Paired t test and Mann-Whitney U tests were used in the statistical analyses. RESULTS: Of the patients 52 were normoglycemic, 21 were hyperglycemic and 27 were diabetic. At the 3rd month of the follow up, 28 patients died. Three patients with temporary hyperglycemia became permanent DM. At baseline, severity of stroke as measured by NIHSS, FM and FIM scores was lower, which was statistically significant (p0.05. Each of the three groups showed significant improvements at the 3rd month after stroke (p<0.05. Normoglycemia group showed the more improvement than diabetic group. CONCLUSION: In this study, it was concluded that temporary hyperglycemia was not infrequent in patients with ischaemic stroke, and that all forms of hyperglycemia played negative role in the severity and prognosis of stroke. It was determined that follow up of temporary hyperglycemia was important for secondary care of these patients.

  5. Mini-Stroke vs. Regular Stroke: What's the Difference?

    Science.gov (United States)

    ... How is a ministroke different from a regular stroke? Answers from Jerry W. Swanson, M.D. When ... brain, spinal cord or retina, which may cause stroke-like symptoms but does not damage brain cells ...

  6. Examination of the relevance of the ICF cores set for stroke by comparing with the Stroke Impact Scale.

    Science.gov (United States)

    Paanalahti, Markku; Berzina, Guna; Lundgren-Nilsson, Åsa; Arndt, Toni; Sunnerhagen, Katharina S

    2018-03-05

    To examine if the International Classification of Functioning (ICF) core set for stoke contains problems that are relevant for the persons living with stroke as expressed in the Stroke Impact Scale (SIS). Cross-sectional study of 242 persons with previous stroke. The agreement between the perceived problems in the SIS items and problems in the categories of Comprehensive ICF Core Set for stroke were analyzed using percent of agreement and Kappa statistic. The analyses between 57 items of the SIS and 31 second-level categories of the ICF were conducted. The problems in domains of "Mobility", "Activities of daily living", "Hand function", "Strength" in the SIS had moderate agreement when compared to ICF categories. The SIS domains of "Emotion" and "Communication", as well as some aspects of the "Memory" had slight or fair agreement with corresponding ICF categories. The results of the study suggest that there is acceptable agreement between persons after stroke and health professionals in the physical aspects, but rather poor agreement in the cognitive and emotional aspects of functioning. Health professionals do not fully capture the magnitude of emotional or social problems experienced by persons after stroke when using the ICF Core Set as a framework for evaluation. Implications for Rehabilitation The ICF Core Set for Stroke provides comprehensive list of possible health and health related outcomes for persons after stroke. Problems reported in condition-specific patient-reported outcome scales can be important in decision making in rehabilitation. Patients and health professionals tend to agree more on physical than cognitive problems. Examination of the relevance of the ICF cores set for stroke by comparing with the Stroke Impact Scale.

  7. Effect of stroke on fall rate, location and predictors: a prospective comparison of older adults with and without stroke.

    Directory of Open Access Journals (Sweden)

    Lisa A Simpson

    Full Text Available BACKGROUND: The literature suggests that stroke is a major risk factor for falls, but there is a lack of prospective, controlled studies which quantify fall-risk after stroke. The purpose of this study was to compare the rates, location and predictors among individuals recently discharged home from stroke rehabilitation to age and sex matched controls. METHODOLOGY/PRINCIPAL FINDINGS: A sample of 80 people with stroke and 90 controls received baseline assessments of balance, mobility and balance confidence. Falls were recorded prospectively over 13 months for both groups. Group differences in fall rates and contribution of clinical measures to falls were determined using negative binomial regression. Fall location was compared between groups using χ(2 statistics. The rate of falls for individuals with stroke was 1.77 times the rate for the control group. People with stroke were more likely to fall at home. Poorer balance (Berg Balance Scale was associated with greater falls for both stroke and control groups (incidence rate ratio [IRR]: 0.908 and IRR: 0.877 respectively. A faster Timed Up and Go Test was associated with greater falls for the stroke group (IRR: 0.955 while better walking endurance (Six Minute Walk Test was associated with greater falls for the controls (IRR: 1.004. Balance confidence was not an independent predictor in either group. CONCLUSIONS: Individuals recently discharged home are at greater risk of falling than individuals without stroke. Attention to home environment is warranted. Balance function can predict falls for both people with stroke and age and sex matched controls. Increased mobility may increase exposure to fall opportunities.

  8. Effect of stroke on fall rate, location and predictors: a prospective comparison of older adults with and without stroke.

    Science.gov (United States)

    Simpson, Lisa A; Miller, William C; Eng, Janice J

    2011-04-29

    The literature suggests that stroke is a major risk factor for falls, but there is a lack of prospective, controlled studies which quantify fall-risk after stroke. The purpose of this study was to compare the rates, location and predictors among individuals recently discharged home from stroke rehabilitation to age and sex matched controls. A sample of 80 people with stroke and 90 controls received baseline assessments of balance, mobility and balance confidence. Falls were recorded prospectively over 13 months for both groups. Group differences in fall rates and contribution of clinical measures to falls were determined using negative binomial regression. Fall location was compared between groups using χ(2) statistics. The rate of falls for individuals with stroke was 1.77 times the rate for the control group. People with stroke were more likely to fall at home. Poorer balance (Berg Balance Scale) was associated with greater falls for both stroke and control groups (incidence rate ratio [IRR]: 0.908 and IRR: 0.877 respectively). A faster Timed Up and Go Test was associated with greater falls for the stroke group (IRR: 0.955) while better walking endurance (Six Minute Walk Test) was associated with greater falls for the controls (IRR: 1.004). Balance confidence was not an independent predictor in either group. Individuals recently discharged home are at greater risk of falling than individuals without stroke. Attention to home environment is warranted. Balance function can predict falls for both people with stroke and age and sex matched controls. Increased mobility may increase exposure to fall opportunities.

  9. Energy Statistics

    International Nuclear Information System (INIS)

    Anon.

    1994-01-01

    For the years 1992 and 1993, part of the figures shown in the tables of the Energy Review are preliminary or estimated. The annual statistics of the Energy Review appear in more detail from the publication Energiatilastot - Energy Statistics issued annually, which also includes historical time series over a longer period. The tables and figures shown in this publication are: Changes in the volume of GNP and energy consumption; Coal consumption; Natural gas consumption; Peat consumption; Domestic oil deliveries; Import prices of oil; Price development of principal oil products; Fuel prices for power production; Total energy consumption by source; Electricity supply; Energy imports by country of origin in 1993; Energy exports by recipient country in 1993; Consumer prices of liquid fuels; Consumer prices of hard coal and natural gas, prices of indigenous fuels; Average electricity price by type of consumer; Price of district heating by type of consumer and Excise taxes and turnover taxes included in consumer prices of some energy sources

  10. STROKE AND PREGNANCY: THE MAIN RISK FACTORS

    Directory of Open Access Journals (Sweden)

    G. K. Taitubayeva

    2017-01-01

    Full Text Available Purpose. To identify risk factors for the development of acute cerebral circulatory impairments (ACCI in pregnant women.Materials and methods. The material for the study was the medical history of 31 pregnant women with diagnosis ACCI. The average age was 29,5 ± 5,1 years. The comparison group consisted of pregnant women with physiological pregnancy (n = 30 with different gestation periods, the mean age was 29,1 ± 6,7 years. In this study, a comparative analysis of risk factors for stroke was carried out: gynecological and allergic history, smoking and taking contraceptives, the presence of chronic diseases, indicators of the hemostasis and lipid spectrum, polymorphism of thrombophilia genes.Results. The prevalence of ischemic stroke over hemorrhagic stroke was found, which was 77.4% and 22.6%, respectively. In 93.5% of cases, a stroke occurred during pregnancy, in 79.3% of them in the third trimester of gestation. The number of recuperated women was 67.7%. As a result of statistical treatment, a significant difference in study and comparison groups was obtained (p < 0.05 as a result of a burdened obstetric-gynecological history. Among the women taking contraceptives, 11 (35.5% women were in the study group, and 3 (10% women were found in the comparison group (p < 0.05. At the analysis of smoking in the history the number of women in the study group prevailed comparing to the comparison group (35.5–13.3%, p < 0.05. Changes in the lipid spectrum system and hemostasis were detected, but there were no significant differences between the study group and the comparison group (p> 0.05. Various forms of mutations were identified in the group with ischemic stroke in 14 (58.3% women, in 2 (28.5% women in the group with hemorrhagic stroke.Conclusion. Of all the data analyzed in pregnant women with stroke, statistically significant risk factors are: smoking, taking contraceptives, the presence of chronic diseases, including an obstructed obstetric

  11. Statistical Optics

    Science.gov (United States)

    Goodman, Joseph W.

    2000-07-01

    The Wiley Classics Library consists of selected books that have become recognized classics in their respective fields. With these new unabridged and inexpensive editions, Wiley hopes to extend the life of these important works by making them available to future generations of mathematicians and scientists. Currently available in the Series: T. W. Anderson The Statistical Analysis of Time Series T. S. Arthanari & Yadolah Dodge Mathematical Programming in Statistics Emil Artin Geometric Algebra Norman T. J. Bailey The Elements of Stochastic Processes with Applications to the Natural Sciences Robert G. Bartle The Elements of Integration and Lebesgue Measure George E. P. Box & Norman R. Draper Evolutionary Operation: A Statistical Method for Process Improvement George E. P. Box & George C. Tiao Bayesian Inference in Statistical Analysis R. W. Carter Finite Groups of Lie Type: Conjugacy Classes and Complex Characters R. W. Carter Simple Groups of Lie Type William G. Cochran & Gertrude M. Cox Experimental Designs, Second Edition Richard Courant Differential and Integral Calculus, Volume I RIchard Courant Differential and Integral Calculus, Volume II Richard Courant & D. Hilbert Methods of Mathematical Physics, Volume I Richard Courant & D. Hilbert Methods of Mathematical Physics, Volume II D. R. Cox Planning of Experiments Harold S. M. Coxeter Introduction to Geometry, Second Edition Charles W. Curtis & Irving Reiner Representation Theory of Finite Groups and Associative Algebras Charles W. Curtis & Irving Reiner Methods of Representation Theory with Applications to Finite Groups and Orders, Volume I Charles W. Curtis & Irving Reiner Methods of Representation Theory with Applications to Finite Groups and Orders, Volume II Cuthbert Daniel Fitting Equations to Data: Computer Analysis of Multifactor Data, Second Edition Bruno de Finetti Theory of Probability, Volume I Bruno de Finetti Theory of Probability, Volume 2 W. Edwards Deming Sample Design in Business Research

  12. Risk Factors and Stroke Characteristic in Patients with Postoperative Strokes.

    Science.gov (United States)

    Dong, Yi; Cao, Wenjie; Cheng, Xin; Fang, Kun; Zhang, Xiaolong; Gu, Yuxiang; Leng, Bing; Dong, Qiang

    2017-07-01

    Intravenous thrombolysis and intra-arterial thrombectomy are now the standard therapies for patients with acute ischemic stroke. In-house strokes have often been overlooked even at stroke centers and there is no consensus on how they should be managed. Perioperative stroke happens rather frequently but treatment protocol is lacking, In China, the issue of in-house strokes has not been explored. The aim of this study is to explore the current management of in-house stroke and identify the common risk factors associated with perioperative strokes. Altogether, 51,841 patients were admitted to a tertiary hospital in Shanghai and the records of those who had a neurological consult for stroke were reviewed. Their demographics, clinical characteristics, in-hospital complications and operations, and management plans were prospectively studied. Routine laboratory test results and risk factors of these patients were analyzed by multiple logistic regression model. From January 1, 2015, to December 31, 2015, over 1800 patients had neurological consultations. Among these patients, 37 had an in-house stroke and 20 had more severe stroke during the postoperative period. Compared to in-house stroke patients without a procedure or operation, leukocytosis and elevated fasting glucose levels were more common in perioperative strokes. In multiple logistic regression model, perioperative strokes were more likely related to large vessel occlusion. Patients with perioperative strokes had different risk factors and severity from other in-house strokes. For these patients, obtaining a neurological consultation prior to surgery may be appropriate in order to evaluate the risk of perioperative stroke. Copyright © 2017. Published by Elsevier Inc.

  13. Stroke risk perception among participants of a stroke awareness campaign

    OpenAIRE

    Kraywinkel, Klaus; Heidrich, Jan; Heuschmann, Peter U; Wagner, Markus; Berger, Klaus

    2007-01-01

    Abstract Background Subjective risk factor perception is an important component of the motivation to change unhealthy life styles. While prior studies assessed cardiovascular risk factor knowledge, little is known about determinants of the individual perception of stroke risk. Methods Survey by mailed questionnaire among 1483 participants of a prior public stroke campaign in Germany. Participants had been informed about their individual stroke risk based on the Framingham stroke risk score. S...

  14. Child-Mediated Stroke Communication: findings from Hip Hop Stroke.

    Science.gov (United States)

    Williams, Olajide; DeSorbo, Alexandra; Noble, James; Gerin, William

    2012-01-01

    Low thrombolysis rates for acute ischemic stroke are linked to delays in seeking immediate treatment due to low public stroke awareness. We aimed to assess whether "Child-Mediated Stroke Communication" could improve stroke literacy of parents of children enrolled in a school-based stroke literacy program called Hip Hop Stroke. Parents of children aged 9 to 12 years from 2 public schools in Harlem, New York City, were recruited to participate in stroke literacy questionnaires before and after their child's participation in Hip Hop Stroke, a novel Child-Mediated Stroke Communication intervention delivered in school auditoriums. Parental recall of stroke information communicated through their child was assessed 1-week after the intervention. Fifth and sixth grade students (n=182) were enrolled into Hip Hop Stroke. One hundred two parents were approached in person to participate; 75 opted to participate and 71 completed both the pretest and post-test (74% response rate and 95% retention rate). Parental stroke literacy improved after the program; before the program, 3 parents of 75 (3.9%) were able to identify the 5 cardinal stroke symptoms, distracting symptom (chest pains), and had an urgent action plan (calling 911) compared with 21 of 71 parents (29.6%) postintervention (P<0.001). The FAST mnemonic was known by 2 (2.7%) of participants before the program versus 29 (41%) after program completion (P<0.001). Knowledge of stroke signs and symptoms remains low among residents of this high-risk population. The use of Child-Mediated Stroke Communication suggests that school children aged 9 to 12 years may be effective conduits of critical stroke knowledge to their parents.

  15. World Stroke Organization Global Stroke Services Guidelines and Action Plan

    OpenAIRE

    Lindsay, Patrice; Furie, Karen L.; Davis, Stephen M.; Donnan, Geoffrey A.; Norrving, Bo

    2014-01-01

    Every two seconds, someone across the globe suffers a symptomatic stroke. 'Silent' cerebrovascular disease insidiously contributes to worldwide disability by causing cognitive impairment in the elderly. The risk of cerebrovascular disease is disproportionately higher in low to middle income countries where there may be barriers to stroke care. The last two decades have seen a major transformation in the stroke field with the emergence of evidence-based approaches to stroke prevention,...

  16. Awareness of risk factors and warning signs of stroke in a Nigeria university.

    Science.gov (United States)

    Obembe, Adebimpe O; Olaogun, Matthew O; Bamikole, Adesola A; Komolafe, Morenikeji A; Odetunde, Marufat O

    2014-04-01

    Rapid access to medical services which is an important predictor of treatment and rehabilitation outcome requires that there is an understanding of stroke risk factors and early warning signs. This study assessed awareness of stroke risk factors and warning signs among students and staff of Obafemi Awolowo University, Nigeria. This was a cross sectional survey involving 994 (500 students and 494 staff) respondents. Information on the awareness of stroke risk factors and warning signs was collected with the aid of a structured questionnaire. Descriptive and inferential statistics were used for data analysis. Weakness (66.2%) was the most commonly identified warning sign of stroke with more staff (69.8%) identifying correctly than students (62.6%). Hypertension (83.4%) was the most commonly identified stroke risk factor, with more staff (91.7%) identifying correctly than students (83.2%). There were significant differences (p stress and obesity), and warning signs (dizziness, numbness, weakness, headache and vision problems) between students and staff. Predictors for adequate awareness of both stroke risk factors and warning signs were younger age, smoking history and higher educational level. Majority of the respondents recognized individual important stroke risk factors and warning signs, but few recognized multiple stroke risk factors and warning signs. Awareness programs on stroke should be organized, even in communities with educated people to increase public awareness on the prevention of stroke and on the reduction of morbidity in the survivors. Copyright © 2014 National Stroke Association. Published by Elsevier Inc. All rights reserved.

  17. Child-Mediated Stroke Communication: Findings from Hip Hop Stroke

    Science.gov (United States)

    Williams, Olajide; DeSorbo, Alexandra; Noble, James; Gerin, William

    2011-01-01

    Background and Purpose Low thrombolysis rates for acute ischemic stroke is linked to delays in seeking immediate treatment due to low public stroke awareness. We aimed to assess whether “Child-Mediated Stroke Communication” (CMSC) could improve stroke literacy parents of children enrolled in a school-based stroke literacy program called Hip Hop Stroke (HHS). Methods Parents of children aged 9 to 12 years from two public schools in Harlem, NYC, were recruited to participate in stroke literacy questionnaires before and after their child’s participation in HHS, a novel CMSC intervention delivered in school auditoriums. Parental recall of stroke information communicated through their child was assessed 1-week following the intervention. Results Fifth and Sixth grade students (n =182) were enrolled into HHS. 102 parents were approached in person to participate; 75 opted to participate and 71 completed both pretest and post-test (74% response rate and 95% retention rate). Parental stroke literacy improved after the program: before the program, 3 parents of 75 (3.9%) were able to identify the five cardinal stroke symptoms, distracting symptom (chest pains), and had an urgent action plan (calling 911), compared to 21 of 71 parents (29.6%) post-intervention (pstroke signs and symptoms remains low among residents of this high-risk population. The use of Child-Mediated Stroke Communication suggests that schoolchildren aged 9-12 may be effective conduits of critical stroke knowledge to their Parents. PMID:22033995

  18. From stroke unit care to stroke care unit

    NARCIS (Netherlands)

    De Keyser, J; Sulter, G.

    1999-01-01

    In some stroke units continuous monitoring of blood pressure, electrocardiogram, body temperature, and oxygen saturation has become an integral part of the management of acute stroke. In addition, regular measurements of blood glucose are performed. Stroke units equipped with such monitoring

  19. Diabetes, Heart Disease, and Stroke

    Science.gov (United States)

    ... Disease, & Other Dental Problems Diabetes & Sexual & Urologic Problems Diabetes, Heart Disease, and Stroke Having diabetes means that ... help to stop. What is the link between diabetes, heart disease, and stroke? Over time, high blood ...

  20. The obesity paradox in stroke

    DEFF Research Database (Denmark)

    Andersen, Klaus Kaae; Olsen, Tom Skyhøj

    2015-01-01

    . Data include age, gender, civil status, stroke severity, computed tomography, and cardiovascular risk factors. Patients were followed up to 9·8 years (median 2·6 years). We used Cox regression models to compare risk of death and readmission for recurrent stroke in the four body mass index groups......BACKGROUND: Although associated with excess mortality and morbidity, obesity is associated with lower mortality after stroke. The association between obesity and risk of recurrent stroke is unclear. AIMS: The study aims to investigate the association in stroke patients between body mass index...... and risk of death and readmission for recurrent stroke. METHODS: An administrative Danish quality-control registry designed to collect a predefined dataset on all hospitalized stroke patients in Denmark 2000–2010 includes 45 615 acute first-ever stroke patients with information on body mass index in 29 326...

  1. Preventable Pediatric Stroke via Vaccination?

    Directory of Open Access Journals (Sweden)

    Craig A. Press

    2015-11-01

    Full Text Available Investigators from the Vascular Effects of Infection in Pediatric Stroke (VIPS group studied the risk of arterial ischemic stroke (AIS associated with minor infection and routine childhood vaccinations.

  2. Causes of Death Data in the Global Burden of Disease Estimates for Ischemic and Hemorrhagic Stroke

    DEFF Research Database (Denmark)

    Truelsen, Thomas; Krarup, Lars-Henrik; Iversen, Helle K

    2015-01-01

    BACKGROUND: Stroke mortality estimates in the Global Burden of Disease (GBD) study are based on routine mortality statistics and redistribution of ill-defined codes that cannot be a cause of death, the so-called 'garbage codes' (GCs). This study describes the contribution of these codes to stroke...

  3. Epidemiology of stroke : the role of blood pressure, alcohol and diet

    NARCIS (Netherlands)

    Keli, S.O.

    1995-01-01

    This thesis evaluates the recent trends in stroke mortality in the Netherlands Antilles, and the role of long-term blood pressure, alcohol and diet as risk factors for stroke incidence. The official mortality statistics and population data from the Netherlands Antilles over the period

  4. ACUTE STROKE: FUNCTIONAL OUTCOME PREDICTORS

    OpenAIRE

    Sujatha; Ramalingam; Vinodkumar; Vasumathi; Valarmathi; Anu

    2016-01-01

    BACKGROUND Ischemic strokes account for >80% of total stroke events. Biochemical modalities like serum uric acid, ESR, CRP, Serum Fibrinogen will be a low cost and useful way to predict functional outcome after ischemic stroke. The Barthel ADL index it is an ordinal scale helping us to measure performances in ADL-activities in daily living. The present study aims to study the Biochemical parameters Uric Acid, CRP, ESR and Fibrinogen in Ischemic Stroke patients and to assess fu...

  5. Women Sex Importance in Stroke Patients with Atrial Fibrillation

    Directory of Open Access Journals (Sweden)

    Cemile Handan Mısırlı

    2014-08-01

    Full Text Available OBJECTIVE: It was shown the differences in age, risk factors and treatment between women and men in stroke patients with atrial fibrillation METHODS: The stroke patients with atrial fibrillation who were hospitalized in our department at the last 2 years were seperated into 2 groups of aged above 75 and below 75, investigated with CHADS2 and CHA2DS2VASc scores and looked at the sex differences of women and men. RESULTS: Stroke ratio according to sex was statistically meaningful especially in women above the age of 75. Risc factors also were founded in elderly women and CHA2DS2VASc scores were higher in women than men so more anticoagulan treatment were begun. No differences were shown between sexes at lone atrial fibrillation and no treatment were begun. CONCLUSION: Women with atrial fibrillation had more risk factors, higher stroke rate and higher anticoagulation treatment.

  6. Energy statistics

    International Nuclear Information System (INIS)

    Anon.

    1989-01-01

    World data from the United Nation's latest Energy Statistics Yearbook, first published in our last issue, are completed here. The 1984-86 data were revised and 1987 data added for world commercial energy production and consumption, world natural gas plant liquids production, world LP-gas production, imports, exports, and consumption, world residual fuel oil production, imports, exports, and consumption, world lignite production, imports, exports, and consumption, world peat production and consumption, world electricity production, imports, exports, and consumption (Table 80), and world nuclear electric power production

  7. Statistical mechanics

    CERN Document Server

    Sheffield, Scott

    2009-01-01

    In recent years, statistical mechanics has been increasingly recognized as a central domain of mathematics. Major developments include the Schramm-Loewner evolution, which describes two-dimensional phase transitions, random matrix theory, renormalization group theory and the fluctuations of random surfaces described by dimers. The lectures contained in this volume present an introduction to recent mathematical progress in these fields. They are designed for graduate students in mathematics with a strong background in analysis and probability. This book will be of particular interest to graduate students and researchers interested in modern aspects of probability, conformal field theory, percolation, random matrices and stochastic differential equations.

  8. SAR: Stroke Authorship Recognition

    KAUST Repository

    Shaheen, Sara

    2015-10-15

    Are simple strokes unique to the artist or designer who renders them? If so, can this idea be used to identify authorship or to classify artistic drawings? Also, could training methods be devised to develop particular styles? To answer these questions, we propose the Stroke Authorship Recognition (SAR) approach, a novel method that distinguishes the authorship of 2D digitized drawings. SAR converts a drawing into a histogram of stroke attributes that is discriminative of authorship. We provide extensive classification experiments on a large variety of data sets, which validate SAR\\'s ability to distinguish unique authorship of artists and designers. We also demonstrate the usefulness of SAR in several applications including the detection of fraudulent sketches, the training and monitoring of artists in learning a particular new style and the first quantitative way to measure the quality of automatic sketch synthesis tools. © 2015 The Eurographics Association and John Wiley & Sons Ltd.

  9. Association of the Single Nucleotide Polymorphisms in microRNAs 130b, 200b, and 495 with Ischemic Stroke Susceptibility and Post-Stroke Mortality.

    Directory of Open Access Journals (Sweden)

    Jinkwon Kim

    Full Text Available The microRNA (miRNA is a small non-coding RNA molecule that modulates gene expression at the posttranscriptional level. Platelets have a crucial role in both hemostasis and thrombosis, a condition that can occlude a cerebral artery and cause ischemic stroke. miR-130b, miR-200b, and miR-495 are potential genetic modulators involving platelet production and activation. We hypothesized that single nucleotide polymorphisms (SNPs in these miRNAs might potentially contribute to the susceptibility to ischemic stroke and post-stroke mortality. This study included 523 ischemic stroke patients and 400 control subjects. We investigated the association of three miRNA SNPs (miR-130bT>C, miR-200bT>C, and miR-495A>C with ischemic stroke prevalence and post-stroke mortality. In the multivariate logistic regression, there was no statistically significant difference in the distribution of miR-130bT>C, miR-200bT>C, or miR-495A>C between the ischemic stroke and control groups. In the subgroup analysis based on ischemic stroke subtype, the miR-200b CC genotype was less frequently found in the large-artery atherosclerosis stroke subtype compared with controls (TT+CT vs CC; adjusted odds ratio for CC, 0.506; 95% confidence interval, 0.265-0.965. During a mean follow-up period of 4.80 ± 2.11 years after stroke onset, there were 106 all-cause deaths among the 523 stroke patients. Multivariate Cox regression analysis did not find a significant association between post-stroke mortality and three miRNA SNPs. Our findings suggest that the functional SNP of miR-200b might be responsible for the susceptibility to large-artery atherosclerotic stroke.

  10. Personal accounts of stroke experiences

    NARCIS (Netherlands)

    Wachters-Kaufmann, CSM

    2000-01-01

    As there appeared to be a need for personal accounts of stroke experiences, a book called "Speaking about Stroke" was written for stroke patients and their caregivers. For the past two years, a questionnaire was sent to the people who had ordered the book, to gain an insight into the characteristics

  11. Questions and Answers about Stroke

    Science.gov (United States)

    ... stroke. High blood pressure increases your risk of stroke four to six times. Heart disease, especially a condition ... leading cause of serious, long-term adult disability. Four million Americans are living with the effects of stroke. The length of time to recover from a ...

  12. Stroke and Episodic Memory Disorders

    Science.gov (United States)

    Lim, Chun; Alexander, Michael P.

    2009-01-01

    Memory impairments are common after stroke, and the anatomical basis for impairments may be quite variable. To determine the range of stroke-related memory impairment, we identified all case reports and group studies through the Medline database and the Science Citation Index. There is no hypothesis about memory that is unique to stroke, but there…

  13. VGC analyzer: a software for statistical analysis of fully crossed multiple-reader multiple-case visual grading characteristics studies

    International Nuclear Information System (INIS)

    Baath, Magnus; Hansson, Jonny

    2016-01-01

    Visual grading characteristics (VGC) analysis is a non-parametric rank-invariant method for analysis of visual grading data. In VGC analysis, image quality ratings for two different conditions are compared by producing a VGC curve, similar to how the ratings for normal and abnormal cases in receiver operating characteristic (ROC) analysis are used to create an ROC curve. The use of established ROC software for the analysis of VGC data has therefore previously been proposed. However, the ROC analysis is based on the assumption of independence between normal and abnormal cases. In VGC analysis, this independence cannot always be assumed, e.g. if the ratings are based on the same patients imaged under both conditions. A dedicated software intended for analysis of VGC studies, which takes possible dependencies between ratings into account in the statistical analysis of a VGC study, has therefore been developed. The software-VGC Analyzer-determines the area under the VGC curve and its uncertainty using non-parametric re-sampling techniques. This article gives an introduction to VGC Analyzer, describes the types of analyses that can be performed and instructs the user about the input and output data. (authors)

  14. Stroke prevention: an update.

    Science.gov (United States)

    Bousser, Marie-Germaine

    2012-03-01

    Stroke is a personal, familial, and social disaster. It is the third cause of death worldwide, the first cause of acquired disability, the second cause of dementia, and its cost is astronomic. The burden of stroke is likely to increase given the aging of the population and the growing incidence of many vascular risk factors. Prevention of stroke includes--as for all other diseases--a "mass approach" aiming at decreasing the risk at the society level and an individual approach, aiming at reducing the risk in a given subject. The mass approach is primarily based on the identification and treatment of vascular risk factors and, if possible, in the implementation of protective factors. These measures are the basis of primary prevention but most of them have now been shown to be also effective in secondary prevention. The individual approach combines a vascular risk factor modification and various treatments addressing the specific subtypes of stroke, such as antiplatelet drugs for the prevention of cerebral infarction in large and small artery diseases of the brain, carotid endarterectomy or stenting for tight carotid artery stenosis, and oral anticoagulants for the prevention of cardiac emboli. There is a growing awareness of the huge evidence-to-practice gap that exists in stroke prevention largely due to socio-economic factors. Recent approaches include low cost intervention packages to reduce blood pressure and cheap "polypills" combining in a single tablet aspirin and several drugs to lower blood pressure and cholesterol. Polypill intake should however not lead to abandon the healthy life-style measures which remain the mainstay of stroke prevention.

  15. The influence of neighborhood unemployment on mortality after stroke.

    Science.gov (United States)

    Unrath, Michael; Wellmann, Jürgen; Diederichs, Claudia; Binse, Lisa; Kalic, Marianne; Heuschmann, Peter Ulrich; Berger, Klaus

    2014-07-01

    Few studies have investigated the impact of neighborhood characteristics on mortality after stroke. Aim of our study was to analyze the influence of district unemployment as indicator of neighborhood socioeconomic status (SES-NH) on poststroke mortality, and to compare these results with the mortality in the underlying general population. Our analyses involve 2 prospective cohort studies from the city of Dortmund, Germany. In the Dortmund Stroke Register (DOST), consecutive stroke patients (N=1883) were recruited from acute care hospitals. In the Dortmund Health Study (DHS), a random general population sample was drawn (n=2291; response rate 66.9%). Vital status was ascertained in the city's registration office and information on district unemployment was obtained from the city's statistical office. We performed multilevel survival analyses to examine the association between district unemployment and mortality. The association between neighborhood unemployment and mortality was weak and not statistically significant in the stroke cohort. Only stroke patients exposed to the highest district unemployment (fourth quartile) had slightly higher mortality risks. In the general population sample, higher district unemployment was significantly associated with higher mortality following a social gradient. After adjustment for education, health-related behavior and morbidity was made the strength of this association decreased. The impact of SES-NH on mortality was different for stroke patients and the general population. Differences in the association between SES-NH and mortality may be partly explained by disease-related characteristics of the stroke cohort such as homogeneous lifestyles, similar morbidity profiles, medical factors, and old age. Copyright © 2014 National Stroke Association. Published by Elsevier Inc. All rights reserved.

  16. 1st Conference of the International Society for Nonparametric Statistics

    CERN Document Server

    Lahiri, S; Politis, Dimitris

    2014-01-01

    This volume is composed of peer-reviewed papers that have developed from the First Conference of the International Society for NonParametric Statistics (ISNPS). This inaugural conference took place in Chalkidiki, Greece, June 15-19, 2012. It was organized with the co-sponsorship of the IMS, the ISI, and other organizations. M.G. Akritas, S.N. Lahiri, and D.N. Politis are the first executive committee members of ISNPS, and the editors of this volume. ISNPS has a distinguished Advisory Committee that includes Professors R.Beran, P.Bickel, R. Carroll, D. Cook, P. Hall, R. Johnson, B. Lindsay, E. Parzen, P. Robinson, M. Rosenblatt, G. Roussas, T. SubbaRao, and G. Wahba. The Charting Committee of ISNPS consists of more than 50 prominent researchers from all over the world.   The chapters in this volume bring forth recent advances and trends in several areas of nonparametric statistics. In this way, the volume facilitates the exchange of research ideas, promotes collaboration among researchers from all over the wo...

  17. A rank-based statistical test for measuring synergistic effects between two gene sets.

    Science.gov (United States)

    Shiraishi, Yuichi; Okada-Hatakeyama, Mariko; Miyano, Satoru

    2011-09-01

    Due to recent advances in high-throughput technologies, data on various types of genomic annotation have accumulated. These data will be crucially helpful for elucidating the combinatorial logic of transcription. Although several approaches have been proposed for inferring cooperativity among multiple factors, most approaches are haunted by the issues of normalization and threshold values. In this article, we propose a rank-based non-parametric statistical test for measuring the effects between two gene sets. This method is free from the issues of normalization and threshold value determination for gene expression values. Furthermore, we have proposed an efficient Markov chain Monte Carlo method for calculating an approximate significance value of synergy. We have applied this approach for detecting synergistic combinations of transcription factor binding motifs and histone modifications. C implementation of the method is available from http://www.hgc.jp/~yshira/software/rankSynergy.zip. yshira@hgc.jp Supplementary data are available at Bioinformatics online.

  18. Ischemic Stroke and Cancer: Stroke Severely Impacts Cancer Patients, While Cancer Increases the Number of Strokes

    OpenAIRE

    Bang, Oh Young; Seok, Jin Myoung; Kim, Seon Gyeong; Hong, Ji Man; Kim, Hahn Young; Lee, Jun; Chung, Pil-Wook; Park, Kwang-Yeol; Kim, Gyeong-Moon; Chung, Chin-Sang; Lee, Kwang Ho

    2011-01-01

    Background Cancer and ischemic stroke are two of the most common causes of death among the elderly, and associations between them have been reported. However, the main pathomechanisms of stroke in cancer patients are not well known, and can only be established based on accurate knowledge of the characteristics of cancer-related strokes. We review herein recent studies concerning the clinical, laboratory, and radiological features of patients with cancer-related stroke. Main Contents This revi...

  19. The Development of Integrated Stroke Care in the Netherlands a Benchmark Study

    Directory of Open Access Journals (Sweden)

    Lidewij E. Vat

    2016-11-01

    Full Text Available Introduction: Integrated stroke care in the Netherlands is constantly changing to strive to better care for stroke patients. The aim of this study was to explore if and on what topics integrated stroke care has been improved in the past three years and if stroke services were further developed. Methods: A web based self-assessment instrument, based on the validated Development Model for Integrated Care, was used to collect data. In total 53 coordinators of stroke services completed the questionnaire with 98 elements and four phases of development concerning the organisation of the stroke service. Data were collected in 2012 and 2015. Descriptive-comparative statistics were used to analyse the data. Results: In 2012, stroke services on average had implemented 56 of the 89 elements of integrated care (range 15–88. In 2015 this was increased up to 70 elements on average (range 37–89. In total, stroke services showed development on all clusters of integrated care. In 2015, more stroke services were in further phases of development like in the consolidation and transformation phase and less were in the initiative and design phase. The results show large differences between individual stroke services. Priorities to further develop stroke services changed over the three years of data collection. Conclusions: Based on the assessment instrument, it was shown that stroke services in the Netherlands were further developed in terms of implemented elements of integrated care and their phase of development. This three year comparison showed unique first analyses over time of integrated stroke care in the Netherlands on a large scale. Interesting further questions are to research the outcomes of stroke care in relation to this development, and if benefits on patient level can be assessed.

  20. Family History in Young Patients With Stroke.

    Science.gov (United States)

    Thijs, Vincent; Grittner, Ulrike; Dichgans, Martin; Enzinger, Christian; Fazekas, Franz; Giese, Anne-Katrin; Kessler, Christof; Kolodny, Edwin; Kropp, Peter; Martus, Peter; Norrving, Bo; Ringelstein, Erich Bernd; Rothwell, Peter M; Schmidt, Reinhold; Tanislav, Christian; Tatlisumak, Turgut; von Sarnowski, Bettina; Rolfs, Arndt

    2015-07-01

    Family history of stroke is an established risk factor for stroke. We evaluated whether family history of stroke predisposed to certain stroke subtypes and whether it differed by sex in young patients with stroke. We used data from the Stroke in Fabry Patients study, a large prospective, hospital-based, screening study for Fabry disease in young patients (aged stroke in whom cardiovascular risk factors and family history of stroke were obtained and detailed stroke subtyping was performed. A family history of stroke was present in 1578 of 4232 transient ischemic attack and ischemic stroke patients (37.3%). Female patients more often had a history of stroke in the maternal lineage (P=0.027) than in the paternal lineage. There was no association with stroke subtype according to Trial of Org 10172 in Acute Stroke Treatment nor with the presence of white matter disease on brain imaging. Patients with dissection less frequently reported a family history of stroke (30.4% versus 36.3%; P=0.018). Patients with a parental history of stroke more commonly had siblings with stroke (3.6% versus 2.6%; P=0.047). Although present in about a third of patients, a family history of stroke is not specifically related to stroke pathogenic subtypes in patients with young stroke. Young women with stroke more often report stroke in the maternal lineage. URL: http://www.clinicaltrials.gov. Unique identifier: NCT00414583. © 2015 American Heart Association, Inc.

  1. Multidetector computed tomography angiography in clinically suspected hyperacute ischemic stroke in the anterior circulation: an etiological workup in a cohort of Brazilian patients

    Directory of Open Access Journals (Sweden)

    Felipe Torres Pacheco

    2015-05-01

    Full Text Available Objective The potential of computed tomography angiography (CTA was assessed for early determination of stroke subtypes in a Brazilian cohort of patients with stroke. Method From July 2011 to July 2013, we selected patients with suspected hyperacute stroke (< 6 hours. Intracranial and cervical arteries were scrutinized on CTA and their imaging features were correlated with concurrent subtype of stroke. Results Stroke was documented in 50/106 selected patients (47.2% based on both clinical grounds and imaging follow-up (stroke group, with statistically significant arterial stenosis and vulnerable plaques on CTA. Intracranial large artery disease was demonstrated in 34% of patients in the stroke group. Partial territorial infarct prevailed (86% while artery-to-artery embolization was the most common stroke mechanism (52%. Conclusion Multidetector CTA was useful for the etiologic work-up of hyperacute ischemic stroke and facilitated the knowledge about the topographic pattern of brain infarct in accordance with its causative mechanism.

  2. Statistically tuned Gaussian background subtraction technique for ...

    Indian Academy of Sciences (India)

    The non-parametric background modelling approach proposed by Martin Hofmann et al (2012) involves modelling of foreground by the history of recently ... background subtraction system with mixture of Gaussians, deviation scaling factor and max– min background model for outdoor environment. Selection of detection ...

  3. Ageism in stroke rehabilitation studies.

    Science.gov (United States)

    Gaynor, Eva Joan; Geoghegan, Sheena Elizabeth; O'Neill, Desmond

    2014-05-01

    stroke is predominantly a disease of older people. While age bias has been demonstrated in studies of pharmacological therapeutic interventions in stroke, the extent of discrimination by age in stroke rehabilitation studies is unknown. The aim of this study was to systematically review the literature to assess the extent of ageism in stroke rehabilitation studies. all randomised control trials (RCT) on stroke rehabilitation entered in the Cochrane database which reported mean age were included. Patient gender and exclusion criteria were also recorded. of 241 RCT's identified, 182 were eligible for inclusion. The mean age of all patients was 64.3, almost a decade younger than those seen by stroke physicians in daily practice in global terms, and 11-12 years younger than encountered in hospital practice in the British Isles. Almost half (46%) of trials excluded patients with cognitive impairment, almost one-quarter (23%) patients with dysphasia and one-eighth (13%) excluded patients with multiple strokes. we have identified a clear difference in the mean age of those included in stroke rehabilitation studies compared with the international mean age of stroke. In addition, a quarter of trials excluded dysphasic patients which may indicate omission of more severe strokes. This means that the evidence base for stroke rehabilitation is deficient in terms of matching the characteristics of patients encountered in clinical practice, and a more representative sample of older people and those with significant disability must be included in future trials.

  4. Stroke? Localized, otogenic meningitis!

    DEFF Research Database (Denmark)

    Ingolfsdottir, Harpa Maria; Thomasen, Per Caye

    2011-01-01

    We report the case of a patient admitted with aphasia, treated for a stroke. Subsequently, it was revealed that the symptoms were caused by complicated otitis media with localized meningitis. This case draws attention to the possible intracranial spread of infection when neurological symptoms occur...

  5. Ischemic strokes and migraine

    International Nuclear Information System (INIS)

    Bousser, M.G.; Baron, J.C.; Chiras, J.

    1985-01-01

    Lasting neurological deficits, though most infrequent, do occur in migrainous subjects and are well documented by clinical angiographic computed tomographic (CT scan) and even pathological studies. However the mechanism of cerebral ischemia in migraine remains widely unknown and the precise role of migraine in the pathogenesis of ischemic strokes is still debated. (orig./MG)

  6. Stroke while jogging.

    OpenAIRE

    Kelly, W. F.; Roussak, J.

    1980-01-01

    Jogging is a form of physical exercise that has stimulated the imagination of the public as shown by recent appearance of its own journal (Jogging Magazine, Editor J. Bryant). We wish to report the unusual complication of an acute stroke sustained during jogging.

  7. Stroke while jogging.

    Science.gov (United States)

    Kelly, W. F.; Roussak, J.

    1980-01-01

    Jogging is a form of physical exercise that has stimulated the imagination of the public as shown by recent appearance of its own journal (Jogging Magazine, Editor J. Bryant). We wish to report the unusual complication of an acute stroke sustained during jogging. Images p229-a Fig. 1 PMID:7448490

  8. Sex differences in stroke.

    NARCIS (Netherlands)

    Haast, R.A.M.; Gustafson, D.R.; Kiliaan, A.J.

    2012-01-01

    Sex differences in stroke are observed across epidemiologic studies, pathophysiology, treatments, and outcomes. These sex differences have profound implications for effective prevention and treatment and are the focus of this review. Epidemiologic studies reveal a clear age-by-sex interaction in

  9. EXAMINATION OF EXECUTIVE DYSFUNCTIONS IN STROKE SURVIVORS VIA 64 – WISCONSIN CARD SORTING TEST

    Directory of Open Access Journals (Sweden)

    Mirena Valkova

    2011-12-01

    Full Text Available Objective: The objective of our study was to examine executive dysfunctions in stroke survivors (three months after stroke via Wisconsin Card Scoring Test (WCST and to assess the influence of stroke severity and lesion location.Contingent and methods: We examined 20 stroke survivors with the following neuropsychological battery: MMSE, 21 – Hamilton test and WCST.Results: We found executive dysfunctions in 90% of our patients. Stroke severity measured by NIHSS influenced MMSE scoring and some of the WCST results (percent conceptual level, trials to complete first category, failure to maintain set and learning abilities. Patients with left hemispheric lesions had statistically significant higher level of total errors than patients with right hemispheric and brainstem lesions.Conclusion: Sub-acute stroke stage is strongly associated with executive dysfunctions

  10. Statistical time series methods for damage diagnosis in a scale aircraft skeleton structure: loosened bolts damage scenarios

    International Nuclear Information System (INIS)

    Kopsaftopoulos, Fotis P; Fassois, Spilios D

    2011-01-01

    A comparative assessment of several vibration based statistical time series methods for Structural Health Monitoring (SHM) is presented via their application to a scale aircraft skeleton laboratory structure. A brief overview of the methods, which are either scalar or vector type, non-parametric or parametric, and pertain to either the response-only or excitation-response cases, is provided. Damage diagnosis, including both the detection and identification subproblems, is tackled via scalar or vector vibration signals. The methods' effectiveness is assessed via repeated experiments under various damage scenarios, with each scenario corresponding to the loosening of one or more selected bolts. The results of the study confirm the 'global' damage detection capability and effectiveness of statistical time series methods for SHM.

  11. Thrombolysis in Postoperative Stroke.

    Science.gov (United States)

    Voelkel, Nicolas; Hubert, Nikolai Dominik; Backhaus, Roland; Haberl, Roman Ludwig; Hubert, Gordian Jan

    2017-11-01

    Intravenous thrombolysis (IVT) is beneficial in reducing disability in selected patients with acute ischemic stroke. There are numerous contraindications to IVT. One is recent surgery. The aim of this study was to analyze the safety of IVT in patients with postoperative stroke. Data of consecutive IVT patients from the Telemedical Project for Integrative Stroke Care thrombolysis registry (February 2003 to October 2014; n=4848) were retrospectively searched for keywords indicating preceding surgery. Patients were included if surgery was performed within the last 90 days before stroke. The primary outcome was defined as surgical site hemorrhage. Subgroups with major/minor surgery and recent/nonrecent surgery (within 10 days before IVT) were analyzed separately. One hundred thirty-four patients underwent surgical intervention before IVT. Surgery had been performed recently (days 1-10) in 49 (37%) and nonrecently (days 11-90) in 85 patients (63%). In 86 patients (64%), surgery was classified as major, and in 48 (36%) as minor. Nine patients (7%) developed surgical site hemorrhage after IVT, of whom 4 (3%) were serious, but none was fatal. One fatal bleeding occurred remotely from surgical area. Rate of surgical site hemorrhage was significantly higher in recent than in nonrecent surgery (14.3% versus 2.4%, respectively, odds ratio adjusted 10.73; 95% confidence interval, 1.88-61.27). Difference between patients with major and minor surgeries was less distinct (8.1% and 4.2%, respectively; odds ratio adjusted 4.03; 95% confidence interval, 0.65-25.04). Overall in-hospital mortality was 8.2%. Intracranial hemorrhage occurred in 9.7% and was asymptomatic in all cases. IVT may be administered safely in postoperative patients as off-label use after appropriate risk-benefit assessment. However, bleeding risk in surgical area should be taken into account particularly in patients who have undergone surgery shortly before stroke onset. © 2017 American Heart Association, Inc.

  12. Imaging of Hemorrhagic Stroke.

    Science.gov (United States)

    Hakimi, Ryan; Garg, Ankur

    2016-10-01

    Hemorrhagic stroke comprises approximately 15% to 20% of all strokes. This article provides readers with an understanding of the indications and significance of various neuroimaging techniques available for patients presenting with hemorrhagic strokes of distinct causes. The most common initial neuroimaging study is a noncontrast head CT, which allows for the identification of hemorrhage. Once an intracranial hemorrhage has been identified, the pattern of blood and the patient's medical history, neurologic examination, and laboratory studies lead the practitioner to pursue further neuroimaging studies to guide the medical, surgical, and interventional management. Given that hemorrhagic stroke constitutes a heterogeneous collection of diagnoses, the subsequent neuroimaging pathway necessary to better evaluate and care for these patients is variable based on the etiology.With an increasing incidence and prevalence of atrial fibrillation associated with the aging population and the introduction of three new direct factor Xa inhibitors and one direct thrombin inhibitor to complement vitamin K antagonists, oral anticoagulant use continues to increase. Patients on oral anticoagulants have a sevenfold to tenfold increased risk for intracerebral hemorrhage (ICH). Furthermore, patients who have an ICH associated with oral anticoagulant use have a higher mortality rate than those with primary ICH. Despite the reduced incidence of hypertension-related ICH over the past decade, it is expected that the incidence of ICH will continue to increase. Neuroimaging studies are integral to the identification of hemorrhagic stroke, determination of the underlying etiology, prevention of hematoma expansion, treatment of acute complications, and treatment of the underlying etiology, if indicated. Neuroimaging is essential for prognostication and thus directly impacts patient care.

  13. Rehabilitating the Stroke Collection

    Directory of Open Access Journals (Sweden)

    Mary Grimmond

    2006-06-01

    Full Text Available Objective The aim of this project was to complete an analysis of monograph and audiovisual items held in the Central Coast Health Service (CCHS Libraries and containing information relevant to the treatment of acute stroke. Acute stroke is treated by multidisciplinary teams of clinicians based at two hospitals within the CCHS. The adequacy of the library collection was measured by subject coverage and age. Methods The methodology used consisted of three main steps: a literature review; design, administration, and analysis of a questionnaire to members of the CCHS Acute Stroke Team; and an analysis of the libraries’ collections. The research project utilised project management methodology and an evidence based librarianship framework. Results The questionnaire revealed that electronic resources were by far the most frequently used by participants, followed in order by print journals, books, interlibrary loan articles, and audiovisual items. Collection analysis demonstrated that the monograph and audiovisual collections were adequate in both scope and currency to support the information needs of Acute Stroke Team members, with the exception of resources to support patient education. Conclusion The researchers developed recommendations for future collection development in the area of acute stroke resources. Conducting this project within the evidence based librarianship framework helped to develop library staff members’ confidence in their ability to make future collection development decisions, informed by the target group’s information needs and preferences. The collection analysis methodology was designed to be replicated, and new specialist groups within the client base of the library will be targeted to repeat the collection analysis process.

  14. Stroke treatment outcomes in hospitals with and without Stroke Units.

    Science.gov (United States)

    Masjuan, J; Gállego Culleré, J; Ignacio García, E; Mira Solves, J J; Ollero Ortiz, A; Vidal de Francisco, D; López-Mesonero, L; Bestué, M; Albertí, O; Acebrón, F; Navarro Soler, I M

    2017-10-23

    Organisational capacity in terms of resources and care circuits to shorten response times in new stroke cases is key to obtaining positive outcomes. This study compares therapeutic approaches and treatment outcomes between traditional care centres (with stroke teams and no stroke unit) and centres with stroke units. We conducted a prospective, quasi-experimental study (without randomisation of the units analysed) to draw comparisons between 2 centres with stroke units and 4 centres providing traditional care through the neurology department, analysing a selection of agreed indicators for monitoring quality of stroke care. A total of 225 patients participated in the study. In addition, self-administered questionnaires were used to collect patients' evaluations of the service and healthcare received. Centres with stroke units showed shorter response times after symptom onset, both in the time taken to arrive at the centre and in the time elapsed from patient's arrival at the hospital to diagnostic imaging. Hospitals with stroke units had greater capacity to respond through the application of intravenous thrombolysis than centres delivering traditional neurological care. Centres with stroke units showed a better fit to the reference standards for stroke response time, as calculated in the Quick study, than centres providing traditional care through the neurology department. Copyright © 2017 Sociedad Española de Neurología. Publicado por Elsevier España, S.L.U. All rights reserved.

  15. Secular trends in ischemic stroke subtypes and stroke risk factors.

    Science.gov (United States)

    Bogiatzi, Chrysi; Hackam, Daniel G; McLeod, A Ian; Spence, J David

    2014-11-01

    Early diagnosis and treatment of a stroke improves patient outcomes, and knowledge of the cause of the initial event is crucial to identification of the appropriate therapy to maximally reduce risk of recurrence. Assumptions based on historical frequency of ischemic subtypes may need revision if stroke subtypes are changing as a result of recent changes in therapy, such as increased use of statins. We analyzed secular trends in stroke risk factors and ischemic stroke subtypes among patients with transient ischemic attack or minor or moderate stroke referred to an urgent transient ischemic attack clinic from 2002 to 2012. There was a significant decline in low-density lipoprotein cholesterol and blood pressure, associated with a significant decline in large artery stroke and small vessel stroke. The proportion of cardioembolic stroke increased from 26% in 2002 to 56% in 2012 (Prisk factors was observed, with a significant decline in stroke/transient ischemic attack caused by large artery atherosclerosis and small vessel disease. As a result, cardioembolic stroke/transient ischemic attack has increased significantly. Our findings suggest that more intensive investigation for cardiac sources of embolism and greater use of anticoagulation may be warranted. © 2014 American Heart Association, Inc.

  16. Outcome Determinants of Stroke in a Brazilian Primary Stroke Center

    Directory of Open Access Journals (Sweden)

    Gustavo W. Kuster

    2014-01-01

    Full Text Available Background. Stroke mortality in Brazil is one of the highest among Western countries. Nonetheless, stroke outcome determinants are still poorly known in this country. In this study we evaluate outcome determinants of stroke in a primary stroke center in São Paulo, Brazil. Methods. We evaluated demographic, clinical, and outcome data of patients with ischemic stroke (IS, transient ischemic attack (TIA, and intracerebral hemorrhage (ICH admitted at “Hospital Paulistano,” São Paulo, Brazil. In-hospital mortality and functional outcome determinants were assessed. Univariate and binary logistic regression analysis were performed. Results. Three hundred forty-one patients were included in the study, 52.2% being male with 66.8±15.7 years. The stroke type distribution was IS: 59.2%, TIA: 29.6%, and ICH: 11.1%. ICH was associated with greater severity and poorer functional outcome. The determinants of poorer functional outcome were higher NIHSS, lower Glasgow score, and lower oxygen saturation level. The most important mortality determinant was the presence of visual symptoms. Conclusions. The stroke mortality and stroke outcome determinants found in the present study do not remarkably differ from studies carried out in developed countries. Stroke prognosis studies are crucial to better understand the high burden of stroke in Brazil.

  17. The social and economic burden of stroke survivors in Italy: a prospective, incidence-based, multi-centre cost of illness study

    Directory of Open Access Journals (Sweden)

    Fattore Giovanni

    2012-11-01

    Full Text Available Abstract Background The aim of this study was to estimate the one-year societal costs due to a stroke event in Italy and to investigate variables associated with costs in different phases following hospital admission. Methods The patients were enrolled in 44 hospitals across the country and data on socio-demographic, clinical variables and resource consumption were prospectively surveyed for 411 stroke survivors at admission, discharge and 3, 6 and 12 months post the event. We adopted a micro-costing procedure to identify cost generating components and the attribution of appropriate unit costs for three cost categories: direct healthcare, direct non-healthcare (including informal care costs and productivity losses. The relation between costs of stroke management and socio-demographic and clinical characteristics as well as disability levels was evaluated in a series of bivariate analyses using non parametric tests (Mann Whitney and Kruskal-Wallis. Multiple linear regression analyses were performed to determine predictors of costs incurred by stroke patients during the acute phase and follow-up of 1 year. Results On average, one-year healthcare and societal costs amounted to €11,747 and € 19,953 per stroke survivor, respectively. The major cost component of societal costs was informal care accounting for € 6,656 (33.4% of total, followed by the initial hospitalisation, (€ 5,573; 27.9% of total, rehabilitation during follow up (€ 4,112; 20.6 %, readmissions (€ 439 and specialist and general practioner visits (€ 326. Mean drug costs per patient over the follow-up period was about € 50 per month. Costs associated to the provision of paid and informal care followed different pattern and were persistent over time (ranging from € 639 to € 597 per month in the first and the second part of the year, respectively. Clinical variables (presence of diabetes mellitus and hemorrhagic stroke were significant predictors of total healthcare

  18. Understanding Stroke - Know Stroke • Know the Signs • Act in Time

    Science.gov (United States)

    ... Home Current Issue Past Issues Special Section Understanding Stroke Know Stroke • Know the Signs • Act in Time Past Issues / ... Julie Harris, and motivational speaker David Layton. Preventing Stroke "Until I had my stroke, I didn't ...

  19. The Disability Rate of 5-Year Post-Stroke and Its Correlation Factors: A National Survey in China.

    Science.gov (United States)

    Yang, Yang; Shi, Yu-Zhi; Zhang, Ning; Wang, Shuo; Ungvari, Gabor S; Ng, Chee H; Wang, Yi-Long; Zhao, Xing-Quan; Wang, Yong-Jun; Wang, Chun-Xue; Xiang, Yu-Tao

    2016-01-01

    Few studies on long-term functional outcome have been conducted in post-stroke patients in China. The objective of this study was to conduct a nationwide survey in China to investigate the 5-year prevalence of post-stroke disability and its correlation factors. A total of 893 patients with ischemic stroke were included. Demographic, clinical and neuro-imaging information were collected with standardized instruments that assessed stroke severity, depression, cognitive impairment, stroke recurrence and physical disability. Disability was assessed with the modified Ranking Score (mRS), of which a cutoff score ≥2 indicates disability. Statistical analysis included chi-square tests, two independent samples t-tests, Mann-Whitney U test and multiple logistic regression analysis. The frequency of disability in this study population was 45%. Multivariate analyses revealed that older age, lower education level, previous history of stroke, stroke severity at admission, depression, cognitive impairment at 3 months, and stroke recurrence within 5 years follow up were all significantly associated with post-stroke disability. The disability rate in 5-year post-stroke was high in Chinese patients. Treatment of depression, secondary prevention of stroke and rehabilitation may benefit disabled patients with stroke in China.

  20. Stupid statistics!

    Science.gov (United States)

    Tellinghuisen, Joel

    2008-01-01

    The method of least squares is probably the most powerful data analysis tool available to scientists. Toward a fuller appreciation of that power, this work begins with an elementary review of statistics fundamentals, and then progressively increases in sophistication as the coverage is extended to the theory and practice of linear and nonlinear least squares. The results are illustrated in application to data analysis problems important in the life sciences. The review of fundamentals includes the role of sampling and its connection to probability distributions, the Central Limit Theorem, and the importance of finite variance. Linear least squares are presented using matrix notation, and the significance of the key probability distributions-Gaussian, chi-square, and t-is illustrated with Monte Carlo calculations. The meaning of correlation is discussed, including its role in the propagation of error. When the data themselves are correlated, special methods are needed for the fitting, as they are also when fitting with constraints. Nonlinear fitting gives rise to nonnormal parameter distributions, but the 10% Rule of Thumb suggests that such problems will be insignificant when the parameter is sufficiently well determined. Illustrations include calibration with linear and nonlinear response functions, the dangers inherent in fitting inverted data (e.g., Lineweaver-Burk equation), an analysis of the reliability of the van't Hoff analysis, the problem of correlated data in the Guggenheim method, and the optimization of isothermal titration calorimetry procedures using the variance-covariance matrix for experiment design. The work concludes with illustrations on assessing and presenting results.

  1. Effects of aspirin plus extended-release dipyridamole versus clopidogrel and telmisartan on disability and cognitive function after recurrent stroke in patients with ischaemic stroke in the Prevention Regimen for Effectively Avoiding Second Strokes (PRoFESS) trial

    DEFF Research Database (Denmark)

    Diener, Hans-Christoph; Sacco, Ralph L; Yusuf, Salim

    2008-01-01

    telmisartan were investigated in the Prevention Regimen for Effectively Avoiding Second Strokes (PRoFESS) trial. METHODS: Patients who had had an ischaemic stroke were randomly assigned in a two by two factorial design to receive either 25 mg aspirin (ASA) and 200 mg extended-release dipyridamole (ER......-DP) twice a day or 75 mg clopidogrel once a day, and either 80 mg telmisartan or placebo once per day. The predefined endpoints for this substudy were disability after a recurrent stroke, assessed with the modified Rankin scale (mRS) and Barthel index at 3 months, and cognitive function, assessed...... of 2.4 years. Recurrent strokes occurred in 916 (9%) patients randomly assigned to ASA with ER-DP and 898 (9%) patients randomly assigned to clopidogrel; 880 (9%) patients randomly assigned to telmisartan and 934 (9%) patients given placebo had recurrent strokes. mRS scores were not statistically...

  2. Neural expert decision support system for stroke diagnosis

    Science.gov (United States)

    Kupershtein, Leonid M.; Martyniuk, Tatiana B.; Krencin, Myhail D.; Kozhemiako, Andriy V.; Bezsmertnyi, Yurii; Bezsmertna, Halyna; Kolimoldayev, Maksat; Smolarz, Andrzej; Weryńska-Bieniasz, RóŻa; Uvaysova, Svetlana

    2017-08-01

    In the work the hybrid expert system for stroke diagnosis was presented. The base of expert system consists of neural network and production rules. This program can quickly and accurately set to the patient preliminary and final diagnoses, get examination and treatment plans, print data of patient, analyze statistics data and perform parameterized search for patients.

  3. THE IMPACT OF COMORBIDITY ON COGNITIVE PARAMETERS AFTER ISCHEMIC STROKE

    Directory of Open Access Journals (Sweden)

    Mirena Valkova

    2012-10-01

    Full Text Available Objective: The aim of our study is to examine the impact of comorbidity on cognitive parameters after the first ever ischemic stroke.Material and methods: We examined 112 patients (aged 46 to 84 (66.67± 5.96, 69 males and 43 females with first ever ischemic stroke. For cognitive assessment we used Mini Mental State Examination (MMSE, 10 word test (for short term memory and delayed recall, Isaack’s test for verbal fluency (VF, Geriatric depression scale (GDS, Hamilton depression scale (HDS, Blessed dementia information memory concentration test (revised, BDIMCT, Benton Visual Retention test (A,E; BVRT – number of corrects and number of errors and Wiskonsin Card Sorting Test (number of errors, WCST. The patients were examined on two step model. At acute stage, after collecting medical history, somatic and neurological examinations, MMSE, 10 words test and HDS were applied. At subacute stroke stage (90±5 days after first stroke symptoms, all cognitive tests were used. „STATGRAPHICS Plus 5.0 (free version” was used for statistical analysis.Results: Chronic ischemic heart disease and chronic obstructive pulmonary disease are the most important additional risk factors for cognitive decline. Thyroid pathology, renal failure and anemia are independently associated with poststroke depression.Conclusions: On the basis of these data we can conclude that vascular risk factors are independently associated with cognitive and emotional changes after stroke and their effects should be assessed and taken into account for subsequent treatment of stroke survivors.

  4. Apraxia and spatial inattention dissociate in left hemisphere stroke.

    Science.gov (United States)

    Timpert, David C; Weiss, Peter H; Vossel, Simone; Dovern, Anna; Fink, Gereon R

    2015-10-01

    Theories of lateralized cognitive functions propose a dominance of the left hemisphere for motor control and of the right hemisphere for spatial attention. Accordingly, spatial attention deficits (e.g., neglect) are more frequently observed after right-hemispheric stroke, whereas apraxia is a common consequence of left-hemispheric stroke. Clinical reports of spatial attentional deficits after left hemisphere (LH) stroke also exist, but are often neglected. By applying parallel analysis (PA) and voxel-based lesion-symptom mapping (VLSM) to data from a comprehensive neuropsychological assessment of 74 LH stroke patients, we here systematically investigate the relationship between spatial inattention and apraxia and their neural bases. PA revealed that apraxic (and language comprehension) deficits loaded on one common component, while deficits in attention tests were explained by another independent component. Statistical lesion analyses with the individual component scores showed that apraxic (and language comprehension) deficits were significantly associated with lesions of the left superior longitudinal fascicle (SLF). Data suggest that in LH stroke spatial attention deficits dissociate from apraxic (and language comprehension) deficits. These findings contribute to models of lateralised cognitive functions in the human brain. Moreover, our findings strongly suggest that LH stroke patients should be assessed systematically for spatial attention deficits so that these can be included in their rehabilitation regime. Copyright © 2015 Elsevier Ltd. All rights reserved.

  5. Inpatient rehabilitation outcomes of patients with apraxia after stroke.

    Science.gov (United States)

    Wu, Andy J; Burgard, Emily; Radel, Jeff

    2014-01-01

    Stroke-induced paresis commands much attention during rehabilitation; other stroke-related consequences receive less consideration. Apraxia is a stroke disorder that may have important implications for rehabilitation and recovery. To investigate association of apraxia with stroke rehabilitation outcomes during inpatient rehabilitation. This cohort study compared patients with and without apraxia after a first left hemispheric stroke. All study patients received standard of care. Clinical measures were the Functional Independence Measure (FIM) and the upper extremity section of the Fugl-Meyer Assessment (FMA) administered upon admission and at discharge. Length of stay was also documented. Florida Apraxia Battery subtests were used to classify patients with apraxia. Fifteen patients were included in this study, 10 of whom had apraxia. Data analysis revealed that patients with apraxia exhibited improvement from admission to discharge in clinical measures; however, admission FIM score was significantly lower compared to patients without apraxia. There was no statistically significant difference between groups on FMA score, length of stay, or amount of change on clinical measures. This study of acute patients found those with apraxia to be significantly less independent upon admission to inpatient rehabilitation compared to patients without apraxia. Although both groups improved a similar amount during rehabilitation, patients with apraxia discharged at a level of independence comparable to patients without apraxia upon admission. Such disparity in independence is of concern, and apraxia as a factor in stroke rehabilitation and recovery deserves further attention.

  6. Lessons from Metabonomics on the Neurobiology of Stroke.

    Science.gov (United States)

    Qureshi, Mahim I; Vorkas, Panagiotis A; Coupland, Alexander P; Jenkins, I Harri; Holmes, Elaine; Davies, Alun H

    2016-10-01

    The application of metabonomic science to interrogate stroke permits the study of metabolite entities, small enough to cross the blood-brain barrier, that provide insight into neuronal dysfunction, and may serve as reservoirs of biomarker discovery. This systematic review examines the applicability of metabolic profiling in ischemic stroke research. Six human studies utilizing metabolic profiling to analyze biofluids from ischemic stroke patients have been included, employing 1 H-NMR and/or mass spectrometry to analyze plasma, serum, and/or urine in a targeted or untargeted fashion. Three are diagnostic studies, and one investigates prognostic biomarkers of stroke recurrence following transient ischemic attack. Two studies focus on metabolic distinguishers of depression or cognitive impairment following stroke. Identified biomarkers from blood and urine predominantly relate to homocysteine and folate, branched chain amino acid, and lipid metabolism. Statistical models are well fitted and reproducible, with excellent validation outcomes, demonstrating the feasibility of metabolic profiling to study a complex disorder with multicausal pathology, such as stroke.

  7. Challenging comparison of stroke scales

    Directory of Open Access Journals (Sweden)

    Kavian Ghandehari

    2013-01-01

    Full Text Available Stroke scales can be classified as clinicometric scales and functional impairment, handicap scales. All studies describing stroke scales were reviewed by internet searching engines with the final search performed on January 1, 2013. The following string of keywords was entered into search engines; stroke, scale, score and disability. Despite advantages of modified National Institute of Health Stroke Scale and Scandinavian stroke scale comparing to the NIHSS, including their simplification and less inter-rater variability; most of the stroke neurologists around the world continue using the NIHSS. The modified Rankin scale (mRS and Barthel index (BI are widely used functional impairment and disability scales. Distinction between grades of mRS is poorly defined. The Asian stroke disability scale is a simplified functional impairment, handicap scale which is as valid as mRS and BI. At the present time, the NIHSS, mRS and BI are routine stroke scales because physicians have used to work with these scales for more than two decades, although it could not be an acceptable reason. On the other side, results of previous stroke trials, which are the basis of stroke management guidelines are driven using these scales.

  8. Post-stroke urinary incontinence.

    Science.gov (United States)

    Mehdi, Z; Birns, J; Bhalla, A

    2013-11-01

    To provide a comprehensive review of the current evidence on post-stroke urinary incontinence. An electronic database search was performed to identify relevant studies and review articles related to Urinary Incontinence (UI) in the stroke population between the years 1966 and 2012. Urinary incontinence following stroke is a common problem affecting more than one-third of acute stroke patients and persisting in up to a quarter at 1 year. It is well established that this condition is a strong marker of stroke severity and is associated with poorer functional outcomes and increased institutionalisation and mortality rates compared with those who remain continent. Despite evidence linking better outcomes to those patients who regain continence, the results of national audits have demonstrated that the management of UI following stroke is suboptimal, with less than two-thirds of stroke units having a documented plan to promote continence. Current evidence supports a thorough assessment to categorise the type and severity of post-stroke urinary incontinence. An individually tailored, structured management strategy to promote continence should be employed. This has been associated with better stroke outcomes and should be the aim of all stroke health professionals. © 2013 John Wiley & Sons Ltd.

  9. Predicting outcome after stroke: the role of basic activities of daily living predicting outcome after stroke.

    Science.gov (United States)

    Gialanella, B; Santoro, R; Ferlucci, C

    2013-10-01

    Very few studies have investigated the influence of single activities of daily living (ADL) at admission as possible predictors of functional outcome after rehabilitation. The aim of the current study was to investigate admission functional status and performance of basic ADLs as assessed by Functional Independence Measure (FIM) scale as possible predictors of motor and functional outcome after stroke during inpatient rehabilitation. This is a prospective and observational study. Inpatients of our Department of Physical Medicine and Rehabilitation. Two hundred sixty consecutive patients with primary diagnosis of stroke were enrolled and 241 patients were used in the final analyses. Two backward stepwise regression analyses were applied to predict outcome. The first backward stepwise regression had age, gender, stroke type, stroke-lesion size, aphasia, neglect, onset to admission interval, Cumulative Illness Rating Scale, National Institute of Health Stroke Scale (NIHSS), Fugl-Meyer Scale, Trunk Control Test, and FIM (total, motor and cognitive scores) as independent variables. The second analyses included the above variables plus FIM items as an independent variable. The dependent variables were the discharge scores and effectiveness in total and motor-FIM, and discharge destination. The first multivariate analysis showed that admission Fugl-Meyer, neglect, total, motor and cognitive FIM scores were the most important predictors of FIM outcomes, while admission NIHSS score was the only predictor of discharge destination. Conversely, when admission single FIM items were included in the statistical model, admission Fugl-Meyer, neglect, grooming, dressing upper body, and social interaction scores were the most important predictors of FIM outcomes, while admission memory and bowel control scores were the only predictors of discharge destination. Our study indicates that performances of basic ADLs are important stroke outcome predictors and among which social

  10. Poststroke depression and risk of recurrent stroke at 1 year in a Chinese cohort study.

    Directory of Open Access Journals (Sweden)

    Huai Wu Yuan

    Full Text Available BACKGROUND: Studies show that poststroke depression (PSD increases mortality risk at 1 year. However, whether PSD increases the risk of recurrent stroke at 1 year remains unclear. This study was to investigate whether PSD at 2 weeks following a stroke could increase risk of recurrent stroke at 1 year. METHODS AND RESULTS: This was a multi-centered prospective cohort study. A total of 2306 patients with acute stroke were enrolled in our study. PSD was diagnosed according to the criteria set by the Diagnostic and Statistical Manual of Mental Disorders, fourth edition (DSM-IV. The outcomes of recurrent stroke were followed up via face-to-face or phone interview. A total of 1713 patients had complete follow-up data, with 481 (28.1% cases of PSD and 158 (9.2% cases of cumulative recurrent stroke at 1 year. Multivariate logistic regression analysis showed a 49% increase of OR of recurrent stroke at 1 year in patients with PSD, compared to patients without PSD following a stroke (OR=1.49, 95%CI: 1.03-2.15. There was no significant correlation between anti-depressant drugs and the risk of recurrent stroke at 1 year following a stroke (OR=1.96, 95%: CI 0.95-4.04. CONCLUSIONS: Based on the DSM-IV diagnostic criteria, nearly 3 out of 10 hospitalized stroke patients in China were diagnosed with PSD at 2 weeks following a stroke. PSD is associated with a higher risk of recurrent stroke at 1 year. Our study did not find benefit of anti-depressant drugs in reducing such risk.

  11. Socioeconomic Status and Stroke Prevalence in Morocco: Results from the Rabat-Casablanca Study

    Science.gov (United States)

    Engels, Thomas; Baglione, Quentin; Audibert, Martine; Viallefont, Anne; Mourji, Fouzi; El Alaoui Faris, Mustapha

    2014-01-01

    Background Stroke is a growing public health concern in low- and middle- income countries. Improved knowledge about the association between socioeconomic status and stroke in these countries would enable the development of effective stroke prevention and management strategies. This study presents the association between socioeconomic status and the prevalence of stroke in Morocco, a lower middle-income country. Methods Data on the prevalence of stroke and stroke-related risk factors were collected during a large population-based survey. The diagnosis of stroke in surviving patients was confirmed by neurologists while health, demographic, and socioeconomic characteristics of households were collected using structured questionnaires. We used Multiple Correspondence Analysis to develop a wealth index based on characteristics of the household dwelling as well as ownership of selected assets. We used logistic regressions controlling for multiple variables to assess the statistical association between socioeconomic status and stroke. Findings Our results showed a significant association between household socioeconomic status and the prevalence of stroke. This relationship was non-linear, with individuals from both the poorest (mainly rural) and richest (mainly urban) households having a lower prevalence of stroke as compared to individuals with medium wealth level. The latter belonged mainly to urban households with a lower socioeconomic status. When taking into account the urban population only, we observed that a third of poorest households experienced a significantly higher prevalence of stroke compared to the richest third (OR = 2.06; CI 95%: 1.09; 3.89). Conclusion We conclude that individuals from the most deprived urban households bear a higher risk of stroke than the rest of the population in Morocco. This result can be explained to a certain extent by the higher presence of behavioral risk factors in this specific category of the population, which leads in

  12. Socioeconomic status and stroke prevalence in Morocco: results from the Rabat-Casablanca study.

    Directory of Open Access Journals (Sweden)

    Thomas Engels

    Full Text Available BACKGROUND: Stroke is a growing public health concern in low- and middle- income countries. Improved knowledge about the association between socioeconomic status and stroke in these countries would enable the development of effective stroke prevention and management strategies. This study presents the association between socioeconomic status and the prevalence of stroke in Morocco, a lower middle-income country. METHODS: Data on the prevalence of stroke and stroke-related risk factors were collected during a large population-based survey. The diagnosis of stroke in surviving patients was confirmed by neurologists while health, demographic, and socioeconomic characteristics of households were collected using structured questionnaires. We used Multiple Correspondence Analysis to develop a wealth index based on characteristics of the household dwelling as well as ownership of selected assets. We used logistic regressions controlling for multiple variables to assess the statistical association between socioeconomic status and stroke. FINDINGS: Our results showed a significant association between household socioeconomic status and the prevalence of stroke. This relationship was non-linear, with individuals from both the poorest (mainly rural and richest (mainly urban households having a lower prevalence of stroke as compared to individuals with medium wealth level. The latter belonged mainly to urban households with a lower socioeconomic status. When taking into account the urban population only, we observed that a third of poorest households experienced a significantly higher prevalence of stroke compared to the richest third (OR = 2.06; CI 95%: 1.09; 3.89. CONCLUSION: We conclude that individuals from the most deprived urban households bear a higher risk of stroke than the rest of the population in Morocco. This result can be explained to a certain extent by the higher presence of behavioral risk factors in this specific category of the population

  13. Non-parametric Bayesian inference for inhomogeneous Markov point processes

    DEFF Research Database (Denmark)

    Berthelsen, Kasper Klitgaard; Møller, Jesper; Johansen, Per Michael

    is a shot noise process, and the interaction function for a pair of points depends only on the distance between the two points and is a piecewise linear function modelled by a marked Poisson process. Simulation of the resulting posterior using a Metropolis-Hastings algorithm in the "conventional" way...... involves evaluating ratios of unknown normalising constants. We avoid this problem by applying a new auxiliary variable technique introduced by Møller, Pettitt, Reeves & Berthelsen (2006). In the present setting the auxiliary variable used is an example of a partially ordered Markov point process model....

  14. Parametric versus non-parametric estimates of climatic trends

    Czech Academy of Sciences Publication Activity Database

    Huth, Radan; Pokorná, Lucie

    2004-01-01

    Roč. 77, - (2004), s. 107-112 ISSN 0177-798X R&D Projects: GA AV ČR IAA3017301 Institutional research plan: CEZ:AV0Z3042911 Keywords : climatology * climatic change * climatic variables Subject RIV: DG - Athmosphere Sciences, Meteorology Impact factor: 0.964, year: 2004

  15. Multi-Directional Non-Parametric Analysis of Agricultural Efficiency

    DEFF Research Database (Denmark)

    Balezentis, Tomas

    to the Multi-Directional Efficiency Analysis approach when the proposed models were employed to analyse empirical data of Lithuanian family farm performance, we saw substantial differences in efficiencies associated with different inputs. In particular, assets appeared to be the least efficiently used input...

  16. A non-parametric 2D deformable template classifier

    DEFF Research Database (Denmark)

    Schultz, Nette; Nielsen, Allan Aasbjerg; Conradsen, Knut

    2005-01-01

    We introduce an interactive segmentation method for a sea floor survey. The method is based on a deformable template classifier and is developed to segment data from an echo sounder post-processor called RoxAnn. RoxAnn collects two different measures for each observation point, and in this 2D...... feature space the ship-master will be able to interactively define a segmentation map, which is refined and optimized by the deformable template algorithms. The deformable templates are defined as two-dimensional vector-cycles. Local random transformations are applied to the vector-cycles, and stochastic...... relaxation in a Bayesian scheme is used. In the Bayesian likelihood a class density function and its estimate hereof is introduced, which is designed to separate the feature space. The method is verified on data collected in Øresund, Scandinavia. The data come from four geographically different areas. Two...

  17. Decision boundary feature selection for non-parametric classifier

    Science.gov (United States)

    Lee, Chulhee; Landgrebe, David A.

    1991-01-01

    Feature selection has been one of the most important topics in pattern recognition. Although many authors have studied feature selection for parametric classifiers, few algorithms are available for feature selection for nonparametric classifiers. In this paper we propose a new feature selection algorithm based on decision boundaries for nonparametric classifiers. We first note that feature selection for pattern recognition is equivalent to retaining 'discriminantly informative features', and a discriminantly informative feature is related to the decision boundary. A procedure to extract discriminantly informative features based on a decision boundary for nonparametric classification is proposed. Experiments show that the proposed algorithm finds effective features for the nonparametric classifier with Parzen density estimation.

  18. Non-parametric analysis of production efficiency of poultry egg ...

    African Journals Online (AJOL)

    ... that enhanced research, extension delivery and farm advisory services should be put in place for farmers to learn the best farm practices carried out on the robustly efficient farms. This will go a long way to increase the efficiency level of the poultry farmers in the study area. Keywords: DEA, efficiency and poultry production

  19. (AJST) RELATIVE EFFICIENCY OF NON-PARAMETRIC ERROR ...

    African Journals Online (AJOL)

    NORBERT OPIYO AKECH

    on 100 bootstrap samples, a sample of size n being taken with replacement in each initial sample of size n. .... the overlap (or optimal error rate) of the populations. However, the expression (2.3) for the computation of ..... Analysis and Machine Intelligence, 9, 628-633. Lachenbruch P. A. (1967). An almost unbiased method ...

  20. Local Dimensionality Reduction for Non-Parametric Regression

    OpenAIRE

    Hoffmann, Heiko; Schaal, Stefan; Vijayakumar, Sethu

    2009-01-01

    Locally-weighted regression is a computationally-efficient technique for non-linear regression. However, for high-dimensional data, this technique becomes numerically brittle and computationally too expensive if many local models need to be maintained simultaneously. Thus, local linear dimensionality reduction combined with locally-weighted regression seems to be a promising solution. In this context, we review linear dimensionalityreduction methods, compare their performance o...

  1. Using non-parametric methods in econometric production analysis

    DEFF Research Database (Denmark)

    Czekaj, Tomasz Gerard; Henningsen, Arne

    Econometric estimation of production functions is one of the most common methods in applied economic production analysis. These studies usually apply parametric estimation techniques, which obligate the researcher to specify the functional form of the production function. Most often, the Cobb...... results—including measures that are of interest of applied economists, such as elasticities. Therefore, we propose to use nonparametric econometric methods. First, they can be applied to verify the functional form used in parametric estimations of production functions. Second, they can be directly used...

  2. A Non-parametric Analysis of Morbidity/Mortality Data

    Science.gov (United States)

    1998-11-01

    estimation of this distribution is to divide the first quadrant of the two dimensional (T,D) plane into rectan- gles Ril, ... , RIj and estimate the...current = 97 - yotourl; /*time from touri to present*/ if t = . and cancer = and d = then do; /*Type 23. No information ***about cancer status and

  3. Guidelines for acute ischemic stroke treatment: part II: stroke treatment

    Directory of Open Access Journals (Sweden)

    Sheila Cristina Ouriques Martins

    2012-11-01

    Full Text Available The second part of these Guidelines covers the topics of antiplatelet, anticoagulant, and statin therapy in acute ischemic stroke, reperfusion therapy, and classification of Stroke Centers. Information on the classes and levels of evidence used in this guideline is provided in Part I. A translated version of the Guidelines is available from the Brazilian Stroke Society website (www.sbdcv.com.br.

  4. For whom the desert bell tolls: heat stroke or stroke

    Directory of Open Access Journals (Sweden)

    Mustafa Bolatkale

    2017-06-01

    Full Text Available Heat stroke is the most complicated and dangerous amongst heat injuries that can lead to irreversible injury and even death with itself or with creating predisposibility to different diseases. The following case report depicts a patient who presented primarily with impairment of consciousness after walking 45 km in the summer heat to cross the Syria-Turkey border and later syncope. This case report aims to highlight the possibility of higher co-incidence with heat stroke and stroke.

  5. British Association of Stroke Physicians: benchmarking survey of stroke services.

    Science.gov (United States)

    Rodgers, Helen; Dennis, Martin; Cohen, David; Rudd, Anthony

    2003-03-01

    the National Service Framework for Older People requires every general hospital which cares for stroke patients to introduce a specialist stroke service by 2004. to describe the organisation and staffing of specialist hospital-based stroke services in the UK. a national postal survey of consultant members of the British Association of Stroke Physicians (BASP) seeking details of the provision of neurovascular clinics, acute stroke units (ASUs), stroke rehabilitation units (SRUs), and the organisation and staffing of these services. the response rate was 91/126 (72%). Fifty-four neurovascular clinics, 40 ASUs and 68 SRUs were identified. Neurovascular clinics used a number of strategies to maintain rapid access and 30 (56%) were run by a single consultant. Only 50% ASUs usually admitted patients within 24 h of stroke. As the number of beds available on ASUs and SRUs did not reflect the total number of stroke in-patients, 21 (53%) ASUs and 45 (79%) SRUs had admission criteria. Training opportunities were limited: 37% ASUs and 82% SRUs had no specialist registrar. The therapy sessions (1 session=half a day) available per bed per week on a SRU were: physiotherapy 0.8; occupational therapy 0.6; speech and language therapy 0.25. significant development is needed to achieve the NSF target for hospital-based stroke services as few Trusts currently have all components in place and even when available not all stroke patients have access to specialist care. Stroke specialists will be required to run these services but training opportunities are currently limited. Stroke unit therapy staffing levels were lower than was available in randomised controlled trials.

  6. Genetic determinants and stroke in children with sickle cell disease,

    Directory of Open Access Journals (Sweden)

    Daniela O.W. Rodrigues

    Full Text Available Abstract Objective: To verify genetic determinants associated with stroke in children with sickle cell disease (SCD. Methods: Prospective cohort with 110 children submitted to neonatal screening by the Neonatal Screening Program, between 1998 and 2007, with SCD diagnosis, followed at a regional reference public service for hemoglobinopathies. The analyzed variables were type of hemoglobinopathy, gender, coexistence with alpha thalassemia (α-thal, haplotypes of the beta globin chain cluster, and stroke. The final analysis was conducted with 66 children with sickle cell anemia (SCA, using the chi-squared test in the program SPSS® version 14.0. Results: Among children with SCD, 60% had SCA. The prevalence of coexistence with α-thal was 30.3% and the Bantu haplotype (CAR was identified in 89.2%. The incidence of stroke was significantly higher in those with SCA (27.3% vs. 2.3%; p = 0.001 and males (24.1% vs. 9.6%; p = 0.044. The presence of α-thal (p = 0.196, the CAR haplotype (p = 0.543, and socioeconomic factors were not statistically significant in association with the occurrence of stroke. Conclusion: There is a high incidence of stroke in male children and in children with SCA. Coexistence with α-thal and haplotypes of the beta globin chain cluster did not show any significant association with stroke. The heterogeneity between previously evaluated populations, the non-reproducibility between studies, and the need to identify factors associated with stroke in patients with SCA indicate the necessity of conducting further research to demonstrate the relevance of genetic factors in stroke related to SCD.

  7. Examining vertebrobasilar artery stroke in two Canadian provinces.

    Science.gov (United States)

    Boyle, Eleanor; Côté, Pierre; Grier, Alexander R; Cassidy, J David

    2009-02-01

    Ecological study. To determine the annual incidence of hospitalized vertebrobasilar artery (VBA) stroke and chiropractic utilization in Saskatchewan and Ontario between 1993 and 2004. To determine whether at an ecological level, the incidence of VBA stroke parallels the incidence of chiropractic utilization. Little is known about the incidence and time trends of VBA stroke diagnoses in the population. Chiropractic manipulation to the neck is believed to be a risk factor for VBA stroke. No study has yet found an association between chiropractic utilization and VBA diagnoses at the population level. All hospitalizations with discharge diagnoses of VBA stroke were extracted from administrative databases for Saskatchewan and Ontario. We included incident cases that were diagnosed between January 1993 and December 2004 for Saskatchewan and from April 1993 to March 2002 for Ontario. VBA cases that had previously been hospitalized for any stroke or transient ischemic attack (TIA) were excluded. Chiropractic utilization was measured using billing data from Saskatchewan Health and Ontario Health Insurance Plan. Denominators were derived from Statistics Canada's annual population estimates. The incidence rate of VBA stroke was 0.855 per 100,000 person-years for Saskatchewan and 0.750 per 100,000 person-years for Ontario. The annual incidence rate spiked dramatically with a 360% increase for Saskatchewan in 2000. There was a 38% increase for the 2000 incidence rate in Ontario. The rate of chiropractic utilization did not increase significantly during the study period. In Saskatchewan, we observed a dramatic increase in the incidence rate in 2000 and there was a corresponding relatively small increase in chiropractic utilization. In Ontario, there was a small increase in the incidence rate; however, chiropractic utilization decreased. At the ecological level, the increase in VBA stroke does not seem to be associated with an increase in the rate of chiropractic utilization.

  8. Hyponatremia And Disability, Prevalence And Prognosis In Babol Stroke Patients.

    Directory of Open Access Journals (Sweden)

    Alijan Ahmadi Ahangar

    2017-02-01

    Full Text Available Background: Stroke is the leading cause of serious long-term disability. In recent studies hyponatremia as a risk factor for stroke. Methods: This cross-sectional descriptive study was to evaluate serum zinc level in serum sodium over the first 24 hours after the onset of stroke. Different intensities were determined on Stroke Scale NIH (National Institute of Health (mild 4-1 and (average moderate 15-5 and (moderate to severe 20-16 and (extreme severe 42- 21. Determination intensity of stroke after admission and discharge with Modified Rankin Scale and Barthel index. Blood serum concentrations of sodium 0.5 mL of venous blood were taken and sodium serum level was performed with Latex particle agglutination test in Ayatollah Rouhani Hospital. That normal range was defined 136-146 meq / L Findings: 125 patients were entered into this study; the prevalence of hyponatremia in female was 70% vs 60% in male. Of stroke patients included in this study 66% of them had hyponatremia and the frequency of hyponatremia in ischemic and hemorrhagic was 82% and 63%, respectively. Increase in hyponatremia with disability period of admission had statistically significant (10(12 mild vs 40(32 moderate, 32(25.6 severe, p=0.01 also with disability before discharge (24(19.2 mild, 26(20.8 moderate, 32(25.6 severe, p=0.03. Conclusions: Hyponatremia can effect on severity of the stroke and can be considered as a predictor of increased stroke severity and disability at admission and discharge.

  9. Genetic determinants and stroke in children with sickle cell disease.

    Science.gov (United States)

    Rodrigues, Daniela O W; Ribeiro, Luiz C; Sudário, Lysla C; Teixeira, Maria T B; Martins, Marina L; Pittella, Anuska M O L; Junior, Irtis de O Fernandes

    To verify genetic determinants associated with stroke in children with sickle cell disease (SCD). Prospective cohort with 110 children submitted to neonatal screening by the Neonatal Screening Program, between 1998 and 2007, with SCD diagnosis, followed at a regional reference public service for hemoglobinopathies. The analyzed variables were type of hemoglobinopathy, gender, coexistence with alpha thalassemia (α-thal), haplotypes of the beta globin chain cluster, and stroke. The final analysis was conducted with 66 children with sickle cell anemia (SCA), using the chi-squared test in the program SPSS ® version 14.0. Among children with SCD, 60% had SCA. The prevalence of coexistence with α-thal was 30.3% and the Bantu haplotype (CAR) was identified in 89.2%. The incidence of stroke was significantly higher in those with SCA (27.3% vs. 2.3%; p=0.001) and males (24.1% vs. 9.6%; p=0.044). The presence of α-thal (p=0.196), the CAR haplotype (p=0.543), and socioeconomic factors were not statistically significant in association with the occurrence of stroke. There is a high incidence of stroke in male children and in children with SCA. Coexistence with α-thal and haplotypes of the beta globin chain cluster did not show any significant association with stroke. The heterogeneity between previously evaluated populations, the non-reproducibility between studies, and the need to identify factors associated with stroke in patients with SCA indicate the necessity of conducting further research to demonstrate the relevance of genetic factors in stroke related to SCD. Copyright © 2016 Sociedade Brasileira de Pediatria. Published by Elsevier Editora Ltda. All rights reserved.

  10. Localization of impaired kinesthetic processing post-stroke

    Directory of Open Access Journals (Sweden)

    Jeffrey Michael Kenzie

    2016-10-01

    Full Text Available Kinesthesia is our sense of limb motion, and allows us to gauge the speed, direction, and amplitude of our movements. Over half of stroke survivors have significant impairments in kinesthesia, which leads to greatly reduced recovery and function in everyday activities. Despite the high reported incidence of kinesthetic deficits after stroke, very little is known about how damage beyond just primary somatosensory areas affects kinesthesia. Stroke provides an ideal model to examine structure-function relationships specific to kinesthetic processing, by comparing lesion location with behavioral impairment. To examine this relationship, we performed voxel-based lesion-symptom mapping and statistical region of interest analyses on a large sample of sub-acute stroke subjects (N=142 and compared kinesthetic performance with stroke lesion location. Subjects with first unilateral, ischemic stroke underwent neuroimaging and a comprehensive robotic kinesthetic assessment (~9 days post-stroke. The robotic exoskeleton measured subjects’ ability to perform a kinesthetic mirror-matching task of the upper limbs without vision. The robot moved the stroke-affected arm and subjects’ mirror-matched the movement with the unaffected arm. We found that lesions both within and outside primary somatosensory cortex were associated with significant kinesthetic impairments. Further, sub-components of kinesthesia were associated with different lesion locations. Impairments in speed perception were primarily associated with lesions to the right post-central and supramarginal gyri whereas impairments in amplitude of movement perception were primarily associated with lesions in the right pre-central gyrus, anterior insula, and superior temporal gyrus. Impairments in perception of movement direction were associated with lesions to bilateral post-central and supramarginal gyri, right superior temporal gyrus and parietal operculum. All measures of impairment shared a common

  11. Localization of Impaired Kinesthetic Processing Post-stroke.

    Science.gov (United States)

    Kenzie, Jeffrey M; Semrau, Jennifer A; Findlater, Sonja E; Yu, Amy Y; Desai, Jamsheed A; Herter, Troy M; Hill, Michael D; Scott, Stephen H; Dukelow, Sean P

    2016-01-01

    Kinesthesia is our sense of limb motion, and allows us to gauge the speed, direction, and amplitude of our movements. Over half of stroke survivors have significant impairments in kinesthesia, which leads to greatly reduced recovery and function in everyday activities. Despite the high reported incidence of kinesthetic deficits after stroke, very little is known about how damage beyond just primary somatosensory areas affects kinesthesia. Stroke provides an ideal model to examine structure-function relationships specific to kinesthetic processing, by comparing lesion location with behavioral impairment. To examine this relationship, we performed voxel-based lesion-symptom mapping and statistical region of interest analyses on a large sample of sub-acute stroke subjects ( N = 142) and compared kinesthetic performance with stroke lesion location. Subjects with first unilateral, ischemic stroke underwent neuroimaging and a comprehensive robotic kinesthetic assessment (~9 days post-stroke). The robotic exoskeleton measured subjects' ability to perform a kinesthetic mirror-matching task of the upper limbs without vision. The robot moved the stroke-affected arm and subjects' mirror-matched the movement with the unaffected arm. We found that lesions both within and outside primary somatosensory cortex were associated with significant kinesthetic impairments. Further, sub-components of kinesthesia were associated with different lesion locations. Impairments in speed perception were primarily associated with lesions to the right post-central and supramarginal gyri whereas impairments in amplitude of movement perception were primarily associated with lesions in the right pre-central gyrus, anterior insula, and superior temporal gyrus. Impairments in perception of movement direction were associated with lesions to bilateral post-central and supramarginal gyri, right superior temporal gyrus and parietal operculum. All measures of impairment shared a common association with

  12. Multiparameter Electromyography Analysis of the Masticatory Muscle Activities in Patients with Brainstem Stroke at Different Head Positions

    Directory of Open Access Journals (Sweden)

    Chuyao Jian

    2017-05-01

    Full Text Available The performance of the masticatory muscle is frequently affected and presents high heterogeneity poststroke. Surface electromyography (EMG is widely used to quantify muscle movement patterns. However, only a few studies applied EMG analysis on the research of masticatory muscle activities poststroke, and most of which used single parameter—root mean squares (RMS. The aim of this study was to fully investigate the performance of masticatory muscle at different head positions in healthy subjects and brainstem stroke patients with multiparameter EMG analysis. In this study, 15 healthy subjects and six brainstem stroke patients were recruited to conduct maximum voluntary clenching at five different head positions: upright position, left rotation, right rotation, dorsal flexion, and ventral flexion. The EMG signals of bilateral temporalis anterior and masseter muscles were recorded, and parameters including RMS, median frequency, and fuzzy approximate entropy of the EMG signals were calculated. Two-way analysis of variance (ANOVA with repeated measures and Bonferroni post hoc test were used to evaluate the effects of muscle and head position on EMG parameters in the healthy group, and the non-parametric Wilcoxon signed rank test was conducted in the patient group. The Welch–Satterthwaite t-test was used to compare the between-subject difference. We found a significant effect of subject and muscles but no significant effect of head positions, and the masticatory muscles of patients after brainstem stroke performed significantly different from healthy subjects. Multiparameter EMG analysis might be an informative tool to investigate the neural activity related movement patterns of the deficient masticatory muscles poststroke.

  13. The post-stroke depression and its impact on functioning in young and adult stroke patients of a rehabilitation unit.

    Science.gov (United States)

    Amaricai, Elena; Poenaru, Dan V

    2016-01-01

    Stroke is a leading cause of disability and a major public health problem. To determine frequency and degree of post-stroke depression (PSD) and its impact on functioning in young and adult stroke patients in a rehabilitation unit. The study included 72 stroke patients (aged 29-59 years) who were attending rehabilitation. The patients were assessed for depressive symptoms by Beck Depression Inventory (BDI), and their functioning by using the Stroke Impact Scale (SIS) and the Barthel Index of Activities of Daily Living (ADL). Forty-eight patients had different degrees of depression: borderline clinical depression (13.8%), moderate depression (34.7%), severe depression (15.2%) or extreme depression (2.9%). There were no significant differences of BDI scores in 30-39, 40-49 and 50-59 years groups. Statistically significant correlations were between BDI score and SIS score, between BDI score and ADL index, and between SIS score and ADL index in men, women and total study patients. More than half of the PSD patients had a moderate degree of depression. Significant correlations were noticed between depressive symptoms and functional status evaluated both by an instrument of assessing stroke impact upon general health and an instrument for assessing the everyday activities.

  14. Hemichorea after ischemic stroke

    Directory of Open Access Journals (Sweden)

    Sadullah Saglam

    2016-03-01

    Full Text Available The deterioration of the balance between direct and indirect ways in the basal ganglia causes chorea. The lesions of contralateral basal ganglia, thalamus or the connection of them all together are responsible for this. Chorea can be observed during the course of metabolic and vascular diseases, neurodegenerative or hereditary diseases. Hyperkinetic movement disorders after acute ischemic stroke are reported as rare; however, hemichorea is the most frequent developing disorder of hyperkinetic movement as a result of cerebrovascular disease. In this case report, we presented two case who applied us with choreiform movements in his left half of the body after acute thalamic stroke. [Cukurova Med J 2016; 41(0.100: 29-32

  15. [Smoking and stroke].

    Science.gov (United States)

    Hashimoto, Yoichiro

    2011-05-01

    Cigarette smoking is a risk factor for the brain infarction (lacunar and atherothrombotic brain infarction) and subarachnoid hemorrhage. Not only active smoking but also passive smoking and smokeless tobacco products pose a risk. The risk after smoking cessation for 5-10 years is equal to that faced by a non-smoker. Many patients continue smoking even after an attack of stroke; therefore, support measures to enforce nonsmoking are required in this high-risk population. We offer nonsmoking support using the 5A approach, and assess the nonsmoking stage (precontemplation, contemplation, preparation, action, and maintenance). We also administer medical therapy for smoking cessation when the patients find it difficult to quit smoking on their own accord. Nicotine dependency needs a follow-up like that required for other risk factors in the primary and secondary prevention of the stroke because smoking is a chronic disease that tends to recur.

  16. Detrusor Hyperreflexia in Stroke

    OpenAIRE

    AYBEK, Zafer

    2014-01-01

    In this study detrusor hyperreflexia was investigated by urodynamic study during the acute phase of stroke in patients who became incontinent after a cerebrovascular accident. Urodynamic studies reveal physiopathological findings of incontinence while the acute period of cerebrovascular accident do not cover neurogenic bladder features. In our study it was observed that most of the patients (60%) had normal bladder functions and detrusor hyperreflexia was a rare rindings. This res...

  17. Stroke Management: Nursing Roles

    OpenAIRE

    Maryam Esmaeili

    2017-01-01

    Introduction: The subacute and long-term assessment and management of patients who have suffered a stroke includes physical therapy and testing to determine the precise etiology of the event so as to prevent recurrence. The acute management differs. Immediate goals include minimizing brain injury, treating medical complications, and moving toward uncovering the pathophysiologic basis of the patient's symptoms. Methods: This is a review paper that report up to date finding with review some...

  18. Central limit theorem: the cornerstone of modern statistics.

    Science.gov (United States)

    Kwak, Sang Gyu; Kim, Jong Hae

    2017-04-01

    According to the central limit theorem, the means of a random sample of size, n , from a population with mean, µ, and variance, σ 2 , distribute normally with mean, µ, and variance, [Formula: see text]. Using the central limit theorem, a variety of parametric tests have been developed under assumptions about the parameters that determine the population probability distribution. Compared to non-parametric tests, which do not require any assumptions about the population probability distribution, parametric tests produce more accurate and precise estimates with higher statistical powers. However, many medical researchers use parametric tests to present their data without knowledge of the contribution of the central limit theorem to the development of such tests. Thus, this review presents the basic concepts of the central limit theorem and its role in binomial distributions and the Student's t-test, and provides an example of the sampling distributions of small populations. A proof of the central limit theorem is also described with the mathematical concepts required for its near-complete understanding.

  19. Confronting passive and active sensors with non-Gaussian statistics.

    Science.gov (United States)

    Rodríguez-Gonzálvez, Pablo; Garcia-Gago, Jesús; Gomez-Lahoz, Javier; González-Aguilera, Diego

    2014-07-30

    This paper has two motivations: firstly, to compare the Digital Surface Models (DSM) derived by passive (digital camera) and by active (terrestrial laser scanner) remote sensing systems when applied to specific architectural objects, and secondly, to test how well the Gaussian classic statistics, with its Least Squares principle, adapts to data sets where asymmetrical gross errors may appear and whether this approach should be changed for a non-parametric one. The field of geomatic technology automation is immersed in a high demanding competition in which any innovation by one of the contenders immediately challenges the opponents to propose a better improvement. Nowadays, we seem to be witnessing an improvement of terrestrial photogrammetry and its integration with computer vision to overcome the performance limitations of laser scanning methods. Through this contribution some of the issues of this "technological race" are examined from the point of view of photogrammetry. A new software is introduced and an experimental test is designed, performed and assessed to try to cast some light on this thrilling match. For the case considered in this study, the results show good agreement between both sensors, despite considerable asymmetry. This asymmetry suggests that the standard Normal parameters are not adequate to assess this type of data, especially when accuracy is of importance. In this case, standard deviation fails to provide a good estimation of the results, whereas the results obtained for the Median Absolute Deviation and for the Biweight Midvariance are more appropriate measures.

  20. Cochrane review: virtual reality for stroke rehabilitation.

    Science.gov (United States)

    Laver, K; George, S; Thomas, S; Deutsch, J E; Crotty, M

    2012-09-01

    Virtual reality and interactive video gaming are innovative therapy approaches in the field of stroke rehabilitation. The primary objective of this review was to determine the effectiveness of virtual reality on motor function after stroke. The impact on secondary outcomes including activities of daily living was also assessed. Randomised and quasi-randomised controlled trials that compared virtual reality with an alternative or no intervention were included in the review. The authors searched the Cochrane Stroke Group Trials Register, the Cochrane Central Register of Controlled Trials, electronic databases, trial registers, reference lists, Dissertation Abstracts, conference proceedings and contacted key researchers and virtual reality manufacturers. Search results were independently examined by two review authors to identify studies meeting the inclusion criteria. Nineteen studies with a total of 565 participants were included in the review. Variation in intervention approaches and outcome data collected limited the extent to which studies could be compared. Virtual reality was found to be significantly more effective than conventional therapy in improving upper limb function (standardised mean difference, SMD) 0.53, 95% confidence intervals [CI] 0.25 to 0.81)) based on seven studies, and activities of daily living (ADL) function (SMD 0.81, 95% CI 0.39 to 1.22) based on three studies. No statistically significant effects were found for grip strength (based on two studies) or gait speed (based on three studies). Virtual reality appears to be a promising approach however, further studies are required to confirm these findings.

  1. Stroke Survivors Scoring Zero on the NIH Stroke Scale Score Still Exhibit Significant Motor Impairment and Functional Limitation

    Directory of Open Access Journals (Sweden)

    Brittany Hand

    2014-01-01

    Full Text Available Objective. To determine the National Institutes of Health Stroke Scale’s (NIHSS’s association with upper extremity (UE impairment and functional outcomes. Design. Secondary, retrospective analysis of randomized controlled trial data. Setting. Not applicable. Participants. 146 subjects with stable, chronic stroke-induced hemiparesis. Intervention. The NIHSS, the UE Fugl-Meyer (FM, and the Arm Motor Ability Test (AMAT were administered prior to their participation in a multicenter randomized controlled trial. Main Outcome Measures. The NIHSS, FM, and AMAT. Results. The association between the NIHSS and UE impairment was statistically significant (P=-0.204;p=0.014 but explained less than 4% of the variance among UE FM scores. The association between NIHSS total score and function as measured by the AMAT was not statistically significant (P=-0.141;p=0.089. Subjects scoring a “zero” on the NIHSS exhibited discernible UE motor deficits and varied scores on the UE FM and AMAT. Conclusion. While being used in stroke trials, the NIHSS may have limited ability to discriminate between treatment responses, even when only a relatively narrow array of impairment levels exists among patients. Given these findings, NIHSS use should be restricted to acute stroke studies and clinical settings with the goal of reporting stroke severity.

  2. Stroke Survivors Scoring Zero on the NIH Stroke Scale Score Still Exhibit Significant Motor Impairment and Functional Limitation.

    Science.gov (United States)

    Hand, Brittany; Page, Stephen J; White, Susan

    2014-01-01

    Objective. To determine the National Institutes of Health Stroke Scale's (NIHSS's) association with upper extremity (UE) impairment and functional outcomes. Design. Secondary, retrospective analysis of randomized controlled trial data. Setting. Not applicable. Participants. 146 subjects with stable, chronic stroke-induced hemiparesis. Intervention. The NIHSS, the UE Fugl-Meyer (FM), and the Arm Motor Ability Test (AMAT) were administered prior to their participation in a multicenter randomized controlled trial. Main Outcome Measures. The NIHSS, FM, and AMAT. Results. The association between the NIHSS and UE impairment was statistically significant (P = -0.204; p = 0.014) but explained less than 4% of the variance among UE FM scores. The association between NIHSS total score and function as measured by the AMAT was not statistically significant (P = -0.141; p = 0.089). Subjects scoring a "zero" on the NIHSS exhibited discernible UE motor deficits and varied scores on the UE FM and AMAT. Conclusion. While being used in stroke trials, the NIHSS may have limited ability to discriminate between treatment responses, even when only a relatively narrow array of impairment levels exists among patients. Given these findings, NIHSS use should be restricted to acute stroke studies and clinical settings with the goal of reporting stroke severity.

  3. Early rehabilitation after stroke.

    Science.gov (United States)

    Bernhardt, Julie; Godecke, Erin; Johnson, Liam; Langhorne, Peter

    2017-02-01

    Early rehabilitation is recommended in many guidelines, with limited evidence to guide practice. Brain neurobiology suggests that early training, at the right dose, will aid recovery. In this review, we highlight recent trials of early mobilization, aphasia, dysphagia and upper limb treatment in which intervention is commenced within 7 days of stroke and discuss future research directions. Trials in this early time window are few. Although the seminal AVERT trial suggests that a cautious approach is necessary immediately (stroke, early mobility training and mobilization appear well tolerated, with few reasons to delay initiating some rehabilitation within the first week. The results of large clinical trials of early aphasia therapy are on the horizon, and examples of targeted upper limb treatments with better patient selection are emerging. Early rehabilitation trials are complex, particularly those that intervene across acute and rehabilitation care settings, but these trials are important if we are to optimize recovery potential in the critical window for repair. Concerted efforts to standardize 'early' recruitment, appropriately stratify participants and implement longer term follow-up is needed. Trial standards are improving. New recommendations from a recent Stroke Recovery and Rehabilitation Roundtable will help drive new research.

  4. Acupuncture for dysphagia in acute stroke.

    Science.gov (United States)

    Xie, Yue; Wang, Liping; He, Jinghua; Wu, Taixiang

    2008-07-16

    measures. Two review authors independently selected trials, assessed trial quality, and extracted data. Disagreements were resolved by a third review author. Only one trial of 66 participants was included. In the acupuncture group, 12 out of 34 participants recovered to normal feeding (35.3%). In the control group, seven out of 32 participants recovered to normal feeding (21.9%). The relative risk of recovery was 1.61 with a 95% confidence interval of 0.73 to 3.58. No statistical significance was detected. There is not enough evidence to make any conclusion about the therapeutic effect of acupuncture for dysphagia after acute stroke. High quality and large scale randomised controlled trials are needed.

  5. Acute Stroke Through the Perspective of a County Hospital: Problems and Opportunities

    Directory of Open Access Journals (Sweden)

    Atay Vural

    2016-04-01

    Full Text Available Objective: Stroke is one of the most important public health issues worldwide, and ranks as the second highest cause of mortality in our country. Regular follow-up of stroke statistics and taking necessary precautions upon determining deficits by countries themselves constitute the most important way of improving prognosis and survival after stroke incidents. To achieve this goal, statistical studies should be performed at various levels of healthcare services. Tertiary care hospitals are the most suitable centers to perform these studies. However, the majority of the population receives service at secondary care centers where the actual statistics remain unknown. The objective of this study was to examine all patients with acute stroke who presented to a county hospital over a one-year period and obtain related data, discuss deficits, and provide solutionbased recommendations. Materials and Methods: All patients diagnosed as having acute stroke between July 2013-July 2014 were included in the study. Demographic, clinical, and radiologic data, in addition to the timing of presentation and baseline National Institutes of Health Stroke Scale (NIHSS scores were recorded retrospectively, and patients were classified by the type of stroke. All patients were followed up for at least one year after the stroke incident and cumulative survival scores were calculated using Kaplan-Meier analysis. Results: Hemorrhagic stroke was determined in four out of 49 patients with acute stroke; the 45 patients diagnosed as having ischemic stroke were included in the study. Among these, 44.4% (n=20 of the patients presented within the first three hours of onset of clinical symptoms, 4.4% (n=2 presented at 3.-4.5 hours. Baseline NIHSS was 1-4 (mild stroke in 50% (n=10 of patients who presented in the first three hours, and >5 (moderate or severe stroke in 50% (n=10 of the remaining patients. The etiologic cause was embolic in 37.1% (n=13, large artery atherosclerosis

  6. Blood glucose in acute stroke

    DEFF Research Database (Denmark)

    Olsen, Tom Skyhøj

    2009-01-01

    Blood glucose is often elevated in acute stroke, and higher admission glucose levels are associated with larger lesions, greater mortality and poorer functional outcome. In patients treated with thrombolysis, hyperglycemia is associated with an increased risk of hemorrhagic transformation...... to the risk of inducing potentially harmful hypoglycemia has been raised. Still, basic and observational research is overwhelmingly in support of a causal relationship between blood glucose and stroke outcome and further research on glucose-lowering therapy in acute stroke is highly warranted....

  7. Acute Stroke Imaging Research Roadmap

    OpenAIRE

    Wintermark, Max; Albers, Gregory W.; Alexandrov, Andrei V.; Alger, Jeffry R.; Bammer, Roland; Baron, Jean-Claude; Davis, Stephen; Demaerschalk, Bart M.; Derdeyn, Colin P.; Donnan, Geoffrey A.; Eastwood, James D.; Fiebach, Jochen B.; Fisher, Marc; Furie, Karen L.; Goldmakher, Gregory V.

    2008-01-01

    The recent “Advanced Neuroimaging for Acute Stroke Treatment” meeting on September 7 and 8, 2007 in Washington DC, brought together stroke neurologists, neuroradiologists, emergency physicians, neuroimaging research scientists, members of the National Institute of Neurological Disorders and Stroke (NINDS), the National Institute of Biomedical Imaging and Bioengineering (NIBIB), industry representatives, and members of the US Food and Drug Administration (FDA) to discuss the role of advanced n...

  8. Problematising risk in stroke rehabilitation.

    Science.gov (United States)

    Egan, Mary Y; Kessler, Dorothy; Ceci, Christine; Laliberté-Rudman, Debbie; McGrath, Colleen; Sikora, Lindsey; Gardner, Paula

    2016-11-01

    Following stroke, re-engagement in personally valued activities requires some experience of risk. Risk, therefore, must be seen as having positive as well as negative aspects in rehabilitation. Our aim was to identify the dominant understanding of risk in stroke rehabilitation and the assumptions underpinning these understandings, determine how these understandings affect research and practise, and if necessary, propose alternate ways to conceptualise risk in research and practise. Alvesson and Sandberg's method of problematisation was used. We began with a historical overview of stroke rehabilitation, and proceeded through five steps undertaken in an iterative fashion: literature search and selection; data extraction; syntheses across texts; identification of assumptions informing the literature and; generation of alternatives. Discussion of risk in stroke rehabilitation is largely implicit. However, two prominent conceptualisations of risk underpin both knowledge development and clinical practise: the risk to the individual stroke survivor of remaining dependent in activities of daily living and the risk that the health care system will be overwhelmed by the costs of providing stroke rehabilitation. Conceptualisation of risk in stroke rehabilitation, while implicit, drives both research and practise in ways that reinforce a focus on impairment and a generic, decontextualised approach to rehabilitation. Implications for rehabilitation Much of stroke rehabilitation practise and research seems to centre implicitly on two risks: risk to the patient of remaining dependent in ADL and risk to the health care system of bankruptcy due to the provision of stroke rehabilitation. The implicit focus on ADL dependence limits the ability of clinicians and researchers to address other goals supportive of a good life following stroke. The implicit focus on financial risk to the health care system may limit access to rehabilitation for people who have experienced either milder or

  9. The Association Between Chlamydia pneumoniae Infection and Ischemic Stroke

    Directory of Open Access Journals (Sweden)

    Eini

    2014-10-01

    Full Text Available Background Chlamydia pneumoniae has been linked with increased risk of cardiovascular diseases; however, data on stroke and cerebrovascular accidents are sparse. Objectives The aim of this study was to determine the association between C. pneumoniae infection and ischemic stroke. Patients and Methods In a case-control study, 141 patients, admitted with ischemic stroke, were compared with gender and age-matched control subjects (n = 141. Using an enzyme-linked immunosorbent assay kit, the presence of C. pneumoniae IgG and IgA in the patients’ sera was determined. The data were analyzed by SPSS software (version 15 and were compared between the two groups using T-test and chi square test. Results The mean ages of the case and control groups were 68.97 ± 12.29 and 66.95 ± 6.68 years old, respectively. The difference between these two groups was not statistically significant (P = 0.102. The seroprevalence of C. pneumoniae-specific IgG were 78.7% in the patients with stroke and 52.5% in the control group. The difference between the two groups was statistically significant (P = 0.0001. The seroprevalence of C. pneumoniae-specific IgA were 41.1% in the stroke and 15.6% in the control group. The difference between the two groups was statistically significant (P = 0.0001. Conclusions The results supported the hypothesis that serological evidence of C. pneumoniae infection may be associated with an increased risk of ischemic stroke and cerebrovascular accident.

  10. Sensitivity to Stroke Emerges in Kindergartners Reading Chinese Script

    Directory of Open Access Journals (Sweden)

    Su Li

    2017-06-01

    Full Text Available To what extent are young children sensitive to individual stroke, the smallest unit of writing in Chinese that carries no phonological or semantic information? The present study examined Chinese kindergartners’ sensitivity to stroke and the contribution of reading ability and age to stroke sensitivity. Fifty five children from Beijing, including 28 4-year-olds (Mage = 4.55 years, SD = 0.28, 16 males and 29 5-year-olds (Mage = 5.58 years, SD = 0.30, 14 males, were administered an orthographic matching task and assessed on non-verbal IQ and Chinese word reading. In the orthographic matching task, children were asked to decide whether two items were exactly the same or different in three conditions, with stimuli being correctly written characters (e.g., “”, stroke-missing or redundant characters (e.g., “”, and Tibetan alphabets (e.g., “”, respectively. The stimuli were presented with E-prime 2.0 software and were displayed on a Surface Pro. Children responded by touching the screen and reaction time was used as a measure of processing efficiency. The 5-year-olds but not the 4-year-olds processed correctly written characters more efficiently than stroke-missing/redundant characters, suggesting emergence of stroke sensitivity from age 5. The 4- and 5-year-olds both processed correctly written characters more efficiently than Tibetan alphabets, ruling out the possibility that the 5 year olds’ sensitivity to stroke was due to the unusual look of the stimuli. Hierarchical regression analyses showed that Chinese word reading explained 10% additional variance in stroke sensitivity after having statistically controlled for age. Age did not account for additional variance in stroke sensitivity after having considered Chinese word reading. Taken together, findings of this study revealed that despite the visually highly complex nature of Chinese and the fact that individual stroke carries no phonological or semantic information, children

  11. Guide to Choosing Stroke Rehabilitation Services

    Science.gov (United States)

    National Stroke Association’s Guide to Choosing Stroke Rehabilitation Services Rehabilitation, often referred to as rehab, is an important part of stroke recovery. Through rehab, you:  Re-learn basic skills such ...

  12. What You Need to Know about Stroke

    Science.gov (United States)

    ... the brain. The other kind of stroke, called hemorrhagic stroke, is caused by a blood vessel that breaks ... are very common among African Americans. The best treatment for stroke is prevention. You can reduce your ...

  13. Epidermoid Causing Ischemic Stroke in the Brainstem

    Directory of Open Access Journals (Sweden)

    Raghvendra Ramdasi

    2014-01-01

    Full Text Available Intracranial tumors may rarely cause stroke. We report an epidermoid cyst causing stroke in a pediatric patient. We have also reviewed the literature and pathogenesis of stroke caused by intracranial tumors.

  14. What Are the Warning Signs of Stroke?

    Science.gov (United States)

    ... Cardiovascular Conditions What Are the Warning Signs of Stroke? Brain tissue affected by blockage Stroke is the fifth leading cause of death in ... over 55 years old have more chance of stroke, and the risk gets greater as you get ...

  15. Risk of ischemic stroke in patients with systemic sclerosis: A systematic review and meta-analysis.

    Science.gov (United States)

    Ungprasert, Patompong; Sanguankeo, Anawin; Upala, Sikarin

    2016-01-01

    Several chronic inflammatory disorders, such as rheumatoid arthritis and idiopathic inflammatory myositis, have been shown to increase risk of ischemic stroke but the data on systemic sclerosis (SSc) remains unclear. We conducted a systematic review and meta-analysis of observational studies that reported odds ratio, relative risk, hazard ratio, or standardized incidence ratio comparing risk of ischemic stroke in patients with SSc versus non-SSc participants. Pooled risk ratio and 95% confidence intervals (CIs) were calculated using a random-effect, generic inverse variance method of DerSimonian and Laird. Four retrospective cohort studies were identified and included in our data analysis. We found a statistically significant elevated ischemic stroke risk in patients with SSc with a pooled risk ratio of 1.68 (95% CI, 1.26-2.24). The statistical heterogeneity was moderate with an I(2) of 69%. Our study demonstrated a statistically significant increased ischemic stroke risk among patients with SSc.

  16. Burden of stroke in Cambodia.

    Science.gov (United States)

    Loo, Keat Wei; Gan, Siew Hua

    2013-08-01

    In Cambodia, stroke is not ranked among the top 10 leading causes of death, but infectious disease are among the top three leading causes of death. This finding could be attributed to a lack of awareness among Cambodians of the signs and symptoms of stroke or to poor reporting, incomplete data, lack of neurologists and neurosurgeons, or low accessibility to the hospitals. The only study of stroke in Cambodia is the Prevalence of Non-Communicable Disease Risk Factors in Cambodia survey, which identified several stroke-related risk factors in the population. Tobacco chewing or smoking is the main risk factor for stroke in Cambodia. Traditional therapies, such as oyt pleung (moxibustion) and jup (cupping), are widely practiced for stroke rehabilitation. In Cambodia, there are few neurologists and few important equipment, such as magnetic resonance imaging machines and computed tomography scanners. The Cambodian government should cooperate with the World Health Organization and the United Nations Children's Fund to attract foreign expertise and technologies to treat stroke patients. © 2012 The Authors. International Journal of Stroke © 2012 World Stroke Organization.

  17. Infections and Ischemic Stroke Outcome

    OpenAIRE

    Grabska, Katarzyna; Gromadzka, Grażyna; Członkowska, Anna

    2011-01-01

    Background. Infections increase the risk of ischemic stroke (IS) and may worsen IS prognosis. Adverse effects of in-hospital infections on stroke outcome were also reported. We aimed to study the prevalence of pre- and poststroke infections and their impact on IS outcome. Methods. We analysed clinical data of 2066 IS patients to assess the effect of pre-stroke and post-stroke infections on IS severity, as well as short-term (up to 30 days) and long-term (90 days) outcome. The independent i...

  18. Stroke scale score and early prediction of outcome after stroke

    International Nuclear Information System (INIS)

    Ahmed, R.; Zuberi, F.Z.; Afsar, S.

    2004-01-01

    Objective: To evaluate the baseline National Institute of Health Stroke Scale (NIHSS) score as a predictor of functional outcome after ischemic stroke. Subjects and Methods: The study included 50 patients who presented to Civil Hospital, Karachi, during the study period with acute stroke and were evaluated with CT scan of brain. Only those patients were enrolled in the study that had acute ischemic stroke. The enrolled subjects were then evaluated for the neurological impairment using National Institute of Health Stroke Scale (NIHSS). The subjects were followed-up and their functional outcome was assessed using Barthel index (BI) on the 7th day of their admission. Results: Of the fifty patients enrolled in the study, 31 (62%) were males and 19 (38%) were females, with age ranging from 45 years to 95 years and a mean age of 59.9 years. Neurological impairment at presentation was assessed by NIHSS. The score ranged between 2 and 28. The functional outcome was evaluated on the 7th day using Barthel index (BI), which ranged from 0 to 80. NIHSS score was found to be a good predictor of functional outcome in patients with ischemic stroke (p<0.001). Other factors like gender, hypertension and heart disease did not affect the functional recovery in such patients. Various factors were found to be significant for early prediction of stroke recovery. The NIHSS score was the strongest predictor of outcome after ischemic stroke. Age at the time of the event was also found to be an important predictor for stroke recovery. Conclusion: The NIHSS score is a good predictor of patient's recovery after stroke. Assessing the patient's neurological impairment at first presentation of ischemic stroke can guide the physician regarding the prognosis and management plan. (author)

  19. Identification of stroke mimics among clinically diagnosed acute strokes.

    Science.gov (United States)

    Tuntiyatorn, Lojana; Saksornchai, Pichaya; Tunlayadechanont, Supoch

    2013-09-01

    Stroke is a clinically syndrome of a sudden onset of neurological deficit in a vascular cause. Stroke mimics is the non-vascular disorders with stroke-like clinical symptoms. It is important to distinguish true stroke from mimics since treatment plan may differ To determine the incidence of the stroke mimics and identify their etiologies. All non-contrast head CT of the patients with clinically diagnosed stroke who immediately received imaging upon arrival at the emergency department of the university hospital were retrospectively reviewed in 12-month period between January 1 and December 31, 2008. Medical records, laboratory results, MRI, and 6-month clinical follow-up records were reviewed for final diagnosis. Seven hundred four patients were included in this study, including 363 (51.5%) men and 341 (48.5%) women with range in age from 24 to 108 years. Amongst those, 417 (59.2%) were ischemic stroke, 80 (11.40%) were hemorrhagic stroke, 186 (26.4%) were stroke-mimics, and 21 (3%) were inconclusive. The etiologies among stroke-mimics were metabolic/intoxication (35, 18.8%), sepsis (28, 15.0%), seizure (21, 11.3%), syncope (20, 10.8%), subdural hemorrhage (14, 7.5%), vertigo (11, 6.0%), brain tumor (10, 5.30%), central nervous system infection (5, 2.7%), others (26, 14.0%), and unspecified (16, 8.6%). Incidence rates and etiologies of the stroke mimics were similar to the western reports. However the frequency of each mimic was not.

  20. A validation study using a modified version of Postural Assessment Scale for Stroke Patients: Postural Stroke Study in Gothenburg (POSTGOT

    Directory of Open Access Journals (Sweden)

    Danielsson Anna

    2011-10-01

    Full Text Available Abstract Background A modified version of Postural Assessment Scale for Stroke Patients (PASS was created with some changes in the description of the items and clarifications in the manual (e.g. much help was defined as support from 2 persons. The aim of this validation study was to assess intrarater and interrater reliability using this modified version of PASS, at a stroke unit, for patients in the acute phase after their first event of stroke. Methods In the intrarater reliability study 114 patients and in the interrater reliability study 15 patients were examined twice with the test within one to 24 hours in the first week after stroke. Spearman's rank correlation, Kappa coefficients, Percentage Agreement and the newer rank-invariant methods; Relative Position, Relative Concentration and Relative rank Variance were used for the statistical analysis. Results For the intrarater reliability Spearman's rank correlations were 0.88-0.98 and k were 0.70-0.93 for the individual items. Small, statistically significant, differences were found for two items regarding Relative Position and for one item regarding Relative Concentration. There was no Relative rank Variance for any single item. For the interrater reliability, Spearman's rank correlations were 0.77-0.99 for individual items. For some items there was a possible, even if not proved, reliability problem regarding Relative Position and Relative Concentration. There was no Relative rank Variance for the single items, except for a small Relative rank Variance for one item. Conclusions The high intrarater and interrater reliability shown for the modified Postural Assessment Scale for Stroke Patients, the Swedish version of Postural Assessment Scale for Stroke Patients, with traditional and newer statistical analyses, particularly for assessments performed by the same rater, support the use of the Swedish version of Postural Assessment Scale for Stroke Patients, in the acute stage after stroke both

  1. Stroke in Saudi children

    International Nuclear Information System (INIS)

    Salih, Mustafa A.; Al-Jarallah, Ahmed A.; Kentab, Anal Y.; Al-Nasser, Mohammad N.; Bahakim, Hassan M.; Kurban, Khadija M.; Zahraa, Jihad N.; Nasir, Ali A.; Abdel-Gader, Abdel-Galil M.; Alorainy, Ibrahim A.; Hassan, Hamdy H.; Kabiraj, Mohammad M.; Khoja, Waleed A.

    2006-01-01

    To describe the epidemiology and clinical features of stroke in a prospective and retrospective cohort of Saudi children and ascertain the causes, pathogenesis, and risk factors. The Retrospective Study Group (RSG) included children with stroke who were evaluated at the Division of Pediatric Neurology, or admitted to King Khalid University Hospital, College of Medicine, King Saud University, Riyadh, Kingdom of Saudi Arabia during the period July 1992 to February 2001. The Prospective Study Group (PSG) included those seen between February 2001 and March 2003. During the combined study periods of 10 years and 7 months, 117 children (61 males and 56 females, aged one month-12 years) were evaluated; the majority (89%) of these were Saudis. The calculated annual hospital frequency rate of stroke was 27.1/100,000 of the pediatric (1month-12 years) population The mean age at onset of the initial stroke in the 104 Saudi children was 27.1 months (SD=39.3 months) median and median was 6 months. Ischemic strokes accounted for the majority of cases (76%). Large-vessel infarcts (LVI, 51.9%) were more common than small-vessel lacunar lesions (SVLL, 19.2%). Five patients (4.8%) had combined LVI and SVLL. Intracranial hemorrhage was less common (18.2%), whereas sinovenous thrombosis was diagnosed in 6 (5.8%) patients. A major risk factor was identified in 94 of 104 (89.4%) Saudi children. Significantly more hematologic disorders and coagulopathies were identified in the PSG compared to the RSG (p=0.001), reflecting a better yield following introduction of more comprehensive hematologic and cogulation laboratory tests during the prospective study period. Hematologic disorders were the most common risk factor (46.2%); presumed perinatal ischemic cerebral injury was risk factor in 23 children (22.1) and infectious and inflammatory disorders of the circulatory system in 18 (17.3%). Congenital and genetic cerebrovascular anomalies were the underlying cause in 7 patients (6.7%) and

  2. Quality of Care and Ischemic Stroke Risk After Hospitalization for Transient Ischemic Attack: Findings From Get With The Guidelines-Stroke.

    Science.gov (United States)

    O'Brien, Emily C; Zhao, Xin; Fonarow, Gregg C; Schulte, Phillip J; Dai, David; Smith, Eric E; Schwamm, Lee H; Bhatt, Deepak L; Xian, Ying; Saver, Jeffrey L; Reeves, Mathew J; Peterson, Eric D; Hernandez, Adrian F

    2015-10-01

    Patients with transient ischemic attack (TIA) are at increased risk for ischemic stroke. We derived a prediction rule for 1-year ischemic stroke risk post-TIA, examining estimated risk, receipt of inpatient quality of care measures for TIA, and the presence or absence of stroke at 1 year post discharge. We linked 67 892 TIA Get With The Guidelines-Stroke patients >65 years (2003-2008) to Medicare inpatient claims to obtain longitudinal outcomes. Using Cox proportional hazards modeling in a split sample, we identified baseline demographics and clinical characteristics associated with ischemic stroke admission during the year post-TIA, and developed a Get With The Guidelines Ischemic Stroke after TIA Risk Score; performance was examined in the validation sample. Quality of care was estimated by a global defect-free care measure, and individual performance measures within estimated risk score quintiles. The overall hospital admission rate for ischemic stroke during the year post-TIA was 5.7%. Patients with ischemic stroke were more likely to be older, black, and have higher rates of smoking, previous stroke, diabetes mellitus, previous myocardial infarction, heart failure, and atrial fibrillation. The Risk Score showed moderate discriminative performance (c-statistic=0.606); highest quintile patients were less likely to receive statins, smoking cessation counseling, and defect-free care. Although not associated with 1-year ischemic stroke, DCF was associated with a significantly lower risk of all-cause mortality. TIA patients with high estimated ischemic stroke risk are less likely to receive defect-free care than low-risk patients. Standardized risk assessment and delivery of optimal inpatient care are needed to reduce this risk-treatment mismatch. © 2015 American Heart Association, Inc.

  3. Validation of the mobility nursing outcome in stroke survivors.

    Science.gov (United States)

    Moreira, Rafaella Pessoa; de Araujo, Thelma Leite; Cavalcante, Tahissa Frota; Guedes, Nirla Gomes; Costa, Alice Gabrielle de Sousa; Lopes, Marcos Venicios de Oliveira

    2013-10-01

    To validate the indicators of the mobility nursing outcome. This is a methodological study carried out from February to April 2011. The instrument was assessed by 23 nurses, and the data were analyzed using SPSS version 16.0. The title "physical mobility" was the most suitable. There was a statistical proportion of less than 85% of experts who agreed that the indicators running, crawling, jumping, and moves with ease were relevant to mobility nursing outcome (p stroke patients. For stroke patients, some indicators are not adequate to their evaluation. This work supports the tools' development to assess accurate outcome measurements in specific populations. © 2013 NANDA International.

  4. Ischemic Stroke: MedlinePlus Health Topic

    Science.gov (United States)

    ... Clots) (American Stroke Association) Let's Talk about Ischemic Stroke (American Heart Association) Also in Spanish Prevention and Risk Factors Carotid Endarterectomy (National Heart, Lung, and Blood Institute) ...

  5. Stroke subtypes and factors associated with ischemic stroke in ...

    African Journals Online (AJOL)

    Stroke subtypes assessed four OCSP (Oxfordshire Communi-. African Health Sciences Vol 15 Issue 1, March 2015. 68. 69 ty Stroke Project Classification) subtypes classification. 13 was used with lacunar circulation infarct (LACI) and total anterior (TACI), partial anterior (PACI), posterior. (POCI) circulation infarcts as non ...

  6. 'This stroke was sent…': Stroke-related illness concepts and ...

    African Journals Online (AJOL)

    Though there is evidence that stroke incidence is increasing even in low and middle income countries, there is no study of stroke-related illness concepts and HSB in Nigerians. Data from 960 educated Nigerians were analysed. Eight hundred and fifty four respondents (431 aged 20-40 years and 423 aged 41 years or ...

  7. Thromboxane biosynthesis in stroke and post-stroke dementia

    NARCIS (Netherlands)

    F. van Kooten (Fop)

    2002-01-01

    textabstractWith 25 to 30 thousand new patients per year and an incidence of 170/100.000, stroke is a major health problem in the Netherlands, as it is in other western countries. It accounts for almost I 0% of the annual death in the Netherlands. Approximately 80% of stroke is of ischemic

  8. Thromboxane biosynthesis in stroke and post-stroke dementia

    NARCIS (Netherlands)

    F. van Kooten (Fop)

    2002-01-01

    textabstractWith 25 to 30 thousand new patients per year and an incidence of 170/100.000, stroke is a major health problem in the Netherlands, as it is in other western countries. It accounts for almost I 0% of the annual death in the Netherlands. Approximately 80% of stroke is of ischemic origin,

  9. Improving Stroke Management through Specialized Stroke Units in ...

    African Journals Online (AJOL)

    ... rehabilitation of the stroke patient. The establishment of stroke units has been found to improve the survival of patients and significantly reduce disability by rendering holistic care. Early intervention to rapidly restore and maintain blood supply to the ischemic area in the brain, minimize brain damage and hence impairment ...

  10. Diagnosis in stroke - an uptake

    International Nuclear Information System (INIS)

    Aichner, F.T.

    2003-01-01

    In practical day-to-day terms, most patients have one of the common causes of stroke: ischemic stroke caused by the complications of atherothrombosis, intracranial small vessel disease, embolism from the heart, primary intracerebral hemorrhage caused by hypertension, or subarachnoid hemorrhage as a result of a ruptured saccular aneurysm. There are three issues to be considered in assessing the reliability of the clinical diagnosis of stroke: the diagnosis of stroke itself: is it a stroke or not; whether the stroke is caused by an infarct or a hemorrhage and particular in ischemic stroke the site and size of the lesion (anterior vs. posterior circulation, lacunar vs. cortical, etc.). No clinical scoring method can differentiate with absolute reliability ischemic stroke from primary intracerebral hemorrhage. To do this brain computed tomography or magnetic resonance imaging is required. For vascular diagnosis ultrasound and magnetic resonance angiography are ideal and complementary non-invasive techniques. Both have no risks and are reasonably sensitive. Catheterangiography is only reserved for patients with subarachnoid hemorrhage with a view to surgical or endovascular treatment or in exceptional cases to establish a more firm prognosis. The diagnosis of ischemic stroke caused by embolism from the heart can only be considered at all if there is an identifiable cardioembolic source which is the case in about 30 % of ischemic stroke, a higher proportion in recent studies using transoesophageal echocardiography. It is not clear that transoesophageal echocardiography provides much more information for clinical decision-making than transthoracic echocardiography, although it certainly provides more anatomical information in selected patients. This article summarizes the diagnostic armamentarium which is used for the diagnosis of stroke and gives an overview of clinically reliable and relevant measures. Refs. 23 (author)

  11. Is there much variation in variation? Revisiting statistics of small area variation in health services research

    Directory of Open Access Journals (Sweden)

    Ibáñez Berta

    2009-04-01

    Full Text Available Abstract Background The importance of Small Area Variation Analysis for policy-making contrasts with the scarcity of work on the validity of the statistics used in these studies. Our study aims at 1 determining whether variation in utilization rates between health areas is higher than would be expected by chance, 2 estimating the statistical power of the variation statistics; and 3 evaluating the ability of different statistics to compare the variability among different procedures regardless of their rates. Methods Parametric bootstrap techniques were used to derive the empirical distribution for each statistic under the hypothesis of homogeneity across areas. Non-parametric procedures were used to analyze the empirical distribution for the observed statistics and compare the results in six situations (low/medium/high utilization rates and low/high variability. A small scale simulation study was conducted to assess the capacity of each statistic to discriminate between different scenarios with different degrees of variation. Results Bootstrap techniques proved to be good at quantifying the difference between the null hypothesis and the variation observed in each situation, and to construct reliable tests and confidence intervals for each of the variation statistics analyzed. Although the good performance of Systematic Component of Variation (SCV, Empirical Bayes (EB statistic shows better behaviour under the null hypothesis, it is able to detect variability if present, it is not influenced by the procedure rate and it is best able to discriminate between different degrees of heterogeneity. Conclusion The EB statistics seems to be a good alternative to more conventional statistics used in small-area variation analysis in health service research because of its robustness.

  12. Therapeutic hypothermia for acute stroke

    DEFF Research Database (Denmark)

    Olsen, Tom Skyhøj; Weber, Uno Jakob; Kammersgaard, Lars Peter

    2003-01-01

    Experimental evidence and clinical experience show that hypothermia protects the brain from damage during ischaemia. There is a growing hope that the prevention of fever in stroke will improve outcome and that hypothermia may be a therapeutic option for the treatment of stroke. Body temperature i...

  13. One Stroke at a Time

    Science.gov (United States)

    Hollibaugh, Molly

    2012-01-01

    At first glance, a Zentangle creation can seem intricate and complicated. But, when you learn how it is done, you realize how simple it is. Zentangles are patterns, or "tangles," that have been reduced to a simple sequence of elemental strokes. When you learn to focus on each stroke you find yourself capable of things that you may have once…

  14. Mortality and use of psychotropic medication in patients with stroke

    DEFF Research Database (Denmark)

    Jennum, Poul; Baandrup, Lone; Iversen, Helle K

    2016-01-01

    OBJECTIVES: The study sought to describe whether psychotropic medication may have long-term side effects in patients with stroke compared with controls. SETTING: Use of national register data from healthcare services were identified from the Danish National Patient Registry in Denmark. Information...... about psychotropic medication use was obtained from the Danish Register of Medicinal Product Statistics. OBJECTIVES: We aimed to evaluate all-cause mortality in relation to the use of benzodiazepines, antidepressants and antipsychotics in patients with stroke and matched controls. PARTICIPANTS: Patients...... with a diagnosis of stroke and either no drug use or preindex use of psychotropic medication (n=49,968) and compared with control subjects (n=86,100) matched on age, gender, marital status and community location. PRIMARY OUTCOME MEASURE: All-cause mortality. RESULTS: All-cause mortality was higher in patients...

  15. The multilevel four-stroke swap engine and its environment

    International Nuclear Information System (INIS)

    Uzdin, Raam; Kosloff, Ronnie

    2014-01-01

    A multilevel four-stroke engine where the thermalization strokes are generated by unitary collisions with thermal bath particles is analyzed. Our model is solvable even when the engine operates far from thermal equilibrium and in the strong system–bath coupling. Necessary operation conditions for the heat machine to perform as an engine or a refrigerator are derived. We relate the work and efficiency of the device to local and non-local statistical properties of the baths (purity, index of coincidence, etc) and put upper bounds on these quantities. Finally, in the ultra-hot regime, we analytically optimize the work and find a striking similarity to results obtained for efficiency at maximal power of classical engines. The complete swap limit of our results holds for any four-stroke quantum Otto engine that is coupled to the baths for periods that are significantly longer than the thermal relaxation time. (paper)

  16. The multilevel four-stroke swap engine and its environment

    Science.gov (United States)

    Uzdin, Raam; Kosloff, Ronnie

    2014-09-01

    A multilevel four-stroke engine where the thermalization strokes are generated by unitary collisions with thermal bath particles is analyzed. Our model is solvable even when the engine operates far from thermal equilibrium and in the strong system-bath coupling. Necessary operation conditions for the heat machine to perform as an engine or a refrigerator are derived. We relate the work and efficiency of the device to local and non-local statistical properties of the baths (purity, index of coincidence, etc) and put upper bounds on these quantities. Finally, in the ultra-hot regime, we analytically optimize the work and find a striking similarity to results obtained for efficiency at maximal power of classical engines. The complete swap limit of our results holds for any four-stroke quantum Otto engine that is coupled to the baths for periods that are significantly longer than the thermal relaxation time.

  17. The Serotonin Transporter Gene Polymorphisms and Risk of Ischemic Stroke.

    Science.gov (United States)

    Mortensen, Janne Kaergaard; Kraglund, Kristian Lundsgaard; Johnsen, Søren Paaske; Mors, Ole; Andersen, Grethe; Buttenschøn, Henriette N

    2018-04-03

    consistent across all stroke subtypes, although not statistically significant. The results remained virtually unchanged, although not reaching statistical significance, when adjusting for age and gender. The presence of the high expression SERT genotype (LALA) may be associated with a lower risk of ischemic stroke/TIA. This is, to our knowledge, the first study examining the SERT gene polymorphisms and the risk of stroke. The present results raise interesting considerations for future personalized medicine potential, and we argue that further larger-scale studies with sufficient power to study subgroups according to stroke etiology and stroke-onset age are needed. © 2018 S. Karger AG, Basel.

  18. Acute Stroke Imaging Research Roadmap

    Science.gov (United States)

    Wintermark, Max; Albers, Gregory W.; Alexandrov, Andrei V.; Alger, Jeffry R.; Bammer, Roland; Baron, Jean-Claude; Davis, Stephen; Demaerschalk, Bart M.; Derdeyn, Colin P.; Donnan, Geoffrey A.; Eastwood, James D.; Fiebach, Jochen B.; Fisher, Marc; Furie, Karen L.; Goldmakher, Gregory V.; Hacke, Werner; Kidwell, Chelsea S.; Kloska, Stephan P.; Köhrmann, Martin; Koroshetz, Walter; Lee, Ting-Yim; Lees, Kennedy R.; Lev, Michael H.; Liebeskind, David S.; Ostergaard, Leif; Powers, William J.; Provenzale, James; Schellinger, Peter; Silbergleit, Robert; Sorensen, Alma Gregory; Wardlaw, Joanna; Wu, Ona; Warach, Steven

    2009-01-01

    The recent “Advanced Neuroimaging for Acute Stroke Treatment” meeting on September 7 and 8, 2007 in Washington DC, brought together stroke neurologists, neuroradiologists, emergency physicians, neuroimaging research scientists, members of the National Institute of Neurological Disorders and Stroke (NINDS), the National Institute of Biomedical Imaging and Bioengineering (NIBIB), industry representatives, and members of the US Food and Drug Administration (FDA) to discuss the role of advanced neuroimaging in acute stroke treatment. The goals of the meeting were to assess state-of-the-art practice in terms of acute stroke imaging research and to propose specific recommendations regarding: (1) the standardization of perfusion and penumbral imaging techniques, (2) the validation of the accuracy and clinical utility of imaging markers of the ischemic penumbra, (3) the validation of imaging biomarkers relevant to clinical outcomes, and (4) the creation of a central repository to achieve these goals. The present article summarizes these recommendations and examines practical steps to achieve them. PMID:18477656

  19. Auditory Hallucinations in Acute Stroke

    Directory of Open Access Journals (Sweden)

    Yair Lampl

    2005-01-01

    Full Text Available Auditory hallucinations are uncommon phenomena which can be directly caused by acute stroke, mostly described after lesions of the brain stem, very rarely reported after cortical strokes. The purpose of this study is to determine the frequency of this phenomenon. In a cross sectional study, 641 stroke patients were followed in the period between 1996–2000. Each patient underwent comprehensive investigation and follow-up. Four patients were found to have post cortical stroke auditory hallucinations. All of them occurred after an ischemic lesion of the right temporal lobe. After no more than four months, all patients were symptom-free and without therapy. The fact the auditory hallucinations may be of cortical origin must be taken into consideration in the treatment of stroke patients. The phenomenon may be completely reversible after a couple of months.

  20. The imaging of ischaemic stroke

    International Nuclear Information System (INIS)

    Hoggard, Nigel; Wilkinson, Iain D.; Griffiths, Paul D.

    2001-01-01

    Stroke is a clinical syndrome of a rapidly developing focal neurological deficit that may be classified for practical purposes into ischaemic and haemorrhagic. The role of imaging is to exclude mimics of ischaemic stroke or intracranial haemorrhage and confirm the presence of an ischaemic stroke. Computed tomography (CT) remains the investigation of choice to exclude acute intracranial haemorrhage but diffusion weighted magnetic resonance (MR) has proved to be a sensitive method of detecting early ischaemic infarction. Perfusion weighted MR allows further assessment at the same examination that could help guide the clinician in the risk/benefit analysis of treatment with thrombolytics or neuroprotective agents under evaluation. This can also be achieved with CT. This review article discusses the imaging of ischaemic stroke, relating the pathophysiology of stroke to it. It deals separately in more detail with these newer MR techniques. Hoggard, N. et al. (2001)