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Sample records for accurate posterior probability

  1. The Estimation of Tree Posterior Probabilities Using Conditional Clade Probability Distributions

    PubMed Central

    Larget, Bret

    2013-01-01

    In this article I introduce the idea of conditional independence of separated subtrees as a principle by which to estimate the posterior probability of trees using conditional clade probability distributions rather than simple sample relative frequencies. I describe an algorithm for these calculations and software which implements these ideas. I show that these alternative calculations are very similar to simple sample relative frequencies for high probability trees but are substantially more accurate for relatively low probability trees. The method allows the posterior probability of unsampled trees to be calculated when these trees contain only clades that are in other sampled trees. Furthermore, the method can be used to estimate the total probability of the set of sampled trees which provides a measure of the thoroughness of a posterior sample. [Bayesian phylogenetics; conditional clade distributions; improved accuracy; posterior probabilities of trees.] PMID:23479066

  2. The estimation of tree posterior probabilities using conditional clade probability distributions.

    PubMed

    Larget, Bret

    2013-07-01

    In this article I introduce the idea of conditional independence of separated subtrees as a principle by which to estimate the posterior probability of trees using conditional clade probability distributions rather than simple sample relative frequencies. I describe an algorithm for these calculations and software which implements these ideas. I show that these alternative calculations are very similar to simple sample relative frequencies for high probability trees but are substantially more accurate for relatively low probability trees. The method allows the posterior probability of unsampled trees to be calculated when these trees contain only clades that are in other sampled trees. Furthermore, the method can be used to estimate the total probability of the set of sampled trees which provides a measure of the thoroughness of a posterior sample. PMID:23479066

  3. Multiclass Posterior Probability Twin SVM for Motor Imagery EEG Classification

    PubMed Central

    She, Qingshan; Ma, Yuliang; Meng, Ming; Luo, Zhizeng

    2015-01-01

    Motor imagery electroencephalography is widely used in the brain-computer interface systems. Due to inherent characteristics of electroencephalography signals, accurate and real-time multiclass classification is always challenging. In order to solve this problem, a multiclass posterior probability solution for twin SVM is proposed by the ranking continuous output and pairwise coupling in this paper. First, two-class posterior probability model is constructed to approximate the posterior probability by the ranking continuous output techniques and Platt's estimating method. Secondly, a solution of multiclass probabilistic outputs for twin SVM is provided by combining every pair of class probabilities according to the method of pairwise coupling. Finally, the proposed method is compared with multiclass SVM and twin SVM via voting, and multiclass posterior probability SVM using different coupling approaches. The efficacy on the classification accuracy and time complexity of the proposed method has been demonstrated by both the UCI benchmark datasets and real world EEG data from BCI Competition IV Dataset 2a, respectively. PMID:26798330

  4. GNSS integer ambiguity validation based on posterior probability

    NASA Astrophysics Data System (ADS)

    Wu, Zemin; Bian, Shaofeng

    2015-10-01

    GNSS integer ambiguity validation is considered to be a challenge task for decades. Several kinds of validation tests are developed and widely used in these years, but theoretical basis is their weakness. Ambiguity validation theoretically is an issue of hypothesis test. In the frame of Bayesian hypothesis testing, posterior probability is the canonical standard that statistical decision should be based on. In this contribution, (i) we derive the posterior probability of the fixed ambiguity based on the Bayesian principle and modify it for practice ambiguity validation. (ii) The optimal property of the posterior probability test is proved based on an extended Neyman-Pearson lemma. Since validation failure rate is the issue users most concerned about, (iii) we derive the failure rate upper bound of the posterior probability test, so the user can use the posterior probability test either in the fixed posterior probability or in the fixed failure rate way. Simulated as well as real observed data are used for experimental validations. The results show that (i) the posterior probability test is the most effective within the R-ratio test, difference test, ellipsoidal integer aperture test and posterior probability test, (ii) the posterior probability test is computational efficient and (iii) the failure rate estimation for posterior probability test is useful.

  5. Posterior Probability Matching and Human Perceptual Decision Making.

    PubMed

    Murray, Richard F; Patel, Khushbu; Yee, Alan

    2015-06-01

    Probability matching is a classic theory of decision making that was first developed in models of cognition. Posterior probability matching, a variant in which observers match their response probabilities to the posterior probability of each response being correct, is being used increasingly often in models of perception. However, little is known about whether posterior probability matching is consistent with the vast literature on vision and hearing that has developed within signal detection theory. Here we test posterior probability matching models using two tools from detection theory. First, we examine the models' performance in a two-pass experiment, where each block of trials is presented twice, and we measure the proportion of times that the model gives the same response twice to repeated stimuli. We show that at low performance levels, posterior probability matching models give highly inconsistent responses across repeated presentations of identical trials. We find that practised human observers are more consistent across repeated trials than these models predict, and we find some evidence that less practised observers more consistent as well. Second, we compare the performance of posterior probability matching models on a discrimination task to the performance of a theoretical ideal observer that achieves the best possible performance. We find that posterior probability matching is very inefficient at low-to-moderate performance levels, and that human observers can be more efficient than is ever possible according to posterior probability matching models. These findings support classic signal detection models, and rule out a broad class of posterior probability matching models for expert performance on perceptual tasks that range in complexity from contrast discrimination to symmetry detection. However, our findings leave open the possibility that inexperienced observers may show posterior probability matching behaviour, and our methods provide new tools for testing for such a strategy. PMID:26079134

  6. Posterior Probability and Fluctuation Theorem in Stochastic Processes

    NASA Astrophysics Data System (ADS)

    Ohkubo, Jun

    2009-12-01

    A generalization of fluctuation theorems in stochastic processes is proposed. The new theorem is written in terms of posterior probabilities, which are introduced via Bayes theorem. In conventional fluctuation theorems, a forward path and its time reversal play an important role, so that a microscopically reversible condition is essential. In contrast, the microscopically reversible condition is not necessary in the new theorem. It is shown that the new theorem recovers various theorems and relations previously known, such as the Gallavotti-Cohen-type fluctuation theorem, the Jarzynski equality, and the Hatano-Sasa relation, when suitable assumptions are employed.

  7. Generalizing Swendsen-Wang to sampling arbitrary posterior probabilities.

    PubMed

    Barbu, Adrian; Zhu, Song-Chun

    2005-08-01

    Many vision tasks can be formulated as graph partition problems that minimize energy functions. For such problems, the Gibbs sampler provides a general solution but is very slow, while other methods, such as Ncut and graph cuts are computationally effective but only work for specific energy forms and are not generally applicable. In this paper, we present a new inference algorithm that generalizes the Swendsen-Wang method to arbitrary probabilities defined on graph partitions. We begin by computing graph edge weights, based on local image features. Then, the algorithm iterates two steps. 1) Graph clustering: It forms connected components by cutting the edges probabilistically based on their weights. 2) Graph relabeling: It selects one connected component and flips probabilistically, the coloring of all vertices in the component simultaneously. Thus, it realizes the split, merge, and regrouping of a "chunk" of the graph, in contrast to Gibbs sampler that flips a single vertex. We prove that this algorithm simulates ergodic and reversible Markov chain jumps in the space of graph partitions and is applicable to arbitrary posterior probabilities or energy functions defined on graphs. We demonstrate the algorithm on two typical problems in computer vision--image segmentation and stereo vision. Experimentally, we show that it is 100-400 times faster in CPU time than the classical Gibbs sampler and 20-40 times faster then the DDMCMC segmentation algorithm. For stereo, we compare performance with graph cuts and belief propagation. We also show that our algorithm can automatically infer generative models and obtain satisfactory results (better than the graphic cuts or belief propagation) in the same amount of time. PMID:16119263

  8. Performance of the Rayleigh task based on the posterior probability of tomographic reconstructions

    SciTech Connect

    Hanson, K.M.

    1991-01-01

    We seek the best possible performance of the Rayleigh task in which one must decide whether a perceived object is a pair of Gaussian-blurred points or a blurred line. Two Bayesian reconstruction algorithms are used, the first based on a Gaussian prior-probability distribution with a nonnegativity constraint and the second based on an entropic prior. In both cases, the reconstructions are found that maximize the posterior probability. We compare the performance of the Rayleigh task obtained with two decision variables, the logarithm of the posterior probability ratio and the change in the mean-squared deviation from the reconstruction. The method of evaluation is based on the results of a numerical testing procedure in which the stated discrimination task is carried out on reconstructions of a randomly generated sequence of images. The ability to perform the Rayleigh task is summarized in terms of a discrimination index that is derived from the area under the receiver-operating characteristic (ROC) curve. We find that the use of the posterior probability does not result in better performance of the Rayleigh task than the mean-squared deviation from the reconstruction. 10 refs., 6 figs.

  9. Quantifying Diagnostic Uncertainty Using Item Response Theory: The Posterior Probability of Diagnosis Index

    PubMed Central

    Lindhiem, Oliver; Kolko, David J.; Yu, Lan

    2013-01-01

    Using traditional Diagnostic and Statistical Manual of Mental Disorders (DSM; American Psychiatric Association, 2000) diagnostic criteria, clinicians are forced to make categorical decisions (diagnosis versus no diagnosis). This forced choice implies that mental and behavioral health disorders are categorical and does not fully characterize varying degrees of uncertainty associated with a particular diagnosis. Using an IRT (latent trait model) framework, we describe the development of the Posterior Probability of Diagnosis (PPOD) Index which answers the question, “What is the likelihood that a patient meets or exceeds the latent trait threshold for a diagnosis.” The PPOD Index is based on the posterior distribution of θ (latent trait score) for each patient’s profile of symptoms. The PPOD Index allows clinicians to quantify and communicate the degree of uncertainty associated with each diagnosis in probabilistic terms. We illustrate the advantages of the PPOD Index in a clinical sample (N = 321) of children and adolescents with Oppositional Defiant Disorder (ODD). PMID:23356682

  10. Reweighting Data in the Spirit of Tukey: Using Bayesian Posterior Probabilities as Rasch Residuals for Studying Misfit

    ERIC Educational Resources Information Center

    Dardick, William R.; Mislevy, Robert J.

    2016-01-01

    A new variant of the iterative "data = fit + residual" data-analytical approach described by Mosteller and Tukey is proposed and implemented in the context of item response theory psychometric models. Posterior probabilities from a Bayesian mixture model of a Rasch item response theory model and an unscalable latent class are expressed

  11. Reweighting Data in the Spirit of Tukey: Using Bayesian Posterior Probabilities as Rasch Residuals for Studying Misfit

    ERIC Educational Resources Information Center

    Dardick, William R.; Mislevy, Robert J.

    2016-01-01

    A new variant of the iterative "data = fit + residual" data-analytical approach described by Mosteller and Tukey is proposed and implemented in the context of item response theory psychometric models. Posterior probabilities from a Bayesian mixture model of a Rasch item response theory model and an unscalable latent class are expressed…

  12. MLIP: using multiple processors to compute the posterior probability of linkage

    PubMed Central

    Govil, Manika; Segre, Alberto M; Vieland, Veronica J

    2008-01-01

    Background Localization of complex traits by genetic linkage analysis may involve exploration of a vast multidimensional parameter space. The posterior probability of linkage (PPL), a class of statistics for complex trait genetic mapping in humans, is designed to model the trait model complexity represented by the multidimensional parameter space in a mathematically rigorous fashion. However, the method requires the evaluation of integrals with no functional form, making it difficult to compute, and thus further test, develop and apply. This paper describes MLIP, a multiprocessor two-point genetic linkage analysis system that supports statistical calculations, such as the PPL, based on the full parameter space implicit in the linkage likelihood. Results The fundamental question we address here is whether the use of additional processors effectively reduces total computation time for a PPL calculation. We use a variety of data – both simulated and real – to explore the question "how close can we get?" to linear speedup. Empirical results of our study show that MLIP does significantly speed up two-point log-likelihood ratio calculations over a grid space of model parameters. Conclusion Observed performance of the program is dependent on characteristics of the data including granularity of the parameter grid space being explored and pedigree size and structure. While work continues to further optimize performance, the current version of the program can already be used to efficiently compute the PPL. Thanks to MLIP, full multidimensional genome scans are now routinely being completed at our centers with runtimes on the order of days, not months or years. PMID:18541055

  13. Building a Model Using Bayesian Network for Assessment of Posterior Probabilities of Falling From Height at Workplaces

    PubMed Central

    Alizadeh, Seyed Shamseddin; Mortazavi, Seyed Bagher; Sepehri, Mohammad Mehdi

    2014-01-01

    Background: Falls from height are one of the main causes of fatal occupational injuries. The objective of this study was to present a model for estimating occurrence probability of falling from height. Methods: In order to make a list of factors affecting falls, we used four expert group's judgment, literature review and an available database. Then the validity and reliability of designed questionnaire were determined and Bayesian networks were built. The built network, nodes and curves were quantified. For network sensitivity analysis, four types of analysis carried out. Results: A Bayesian network for assessment of posterior probabilities of falling from height proposed. The presented Bayesian network model shows the interrelationships among 37 causes affecting the falling from height and can calculate its posterior probabilities. The most important factors affecting falling were Non-compliance with safety instructions for work at height (0.127), Lack of safety equipment for work at height (0.094) and Lack of safety instructions for work at height (0.071) respectively. Conclusion: The proposed Bayesian network used to determine how different causes could affect the falling from height at work. The findings of this study can be used to decide on the falling accident prevention programs. PMID:25648498

  14. On the use of posterior predictive probabilities and prediction uncertainty to tailor informative sampling for parasitological surveillance in livestock.

    PubMed

    Musella, Vincenzo; Rinaldi, Laura; Lagazio, Corrado; Cringoli, Giuseppe; Biggeri, Annibale; Catelan, Dolores

    2014-09-15

    Model-based geostatistics and Bayesian approaches are appropriate in the context of Veterinary Epidemiology when point data have been collected by valid study designs. The aim is to predict a continuous infection risk surface. Little work has been done on the use of predictive infection probabilities at farm unit level. In this paper we show how to use predictive infection probability and related uncertainty from a Bayesian kriging model to draw a informative samples from the 8794 geo-referenced sheep farms of the Campania region (southern Italy). Parasitological data come from a first cross-sectional survey carried out to study the spatial distribution of selected helminths in sheep farms. A grid sampling was performed to select the farms for coprological examinations. Faecal samples were collected for 121 sheep farms and the presence of 21 different helminths were investigated using the FLOTAC technique. The 21 responses are very different in terms of geographical distribution and prevalence of infection. The observed prevalence range is from 0.83% to 96.69%. The distributions of the posterior predictive probabilities for all the 21 parasites are very heterogeneous. We show how the results of the Bayesian kriging model can be used to plan a second wave survey. Several alternatives can be chosen depending on the purposes of the second survey: weight by posterior predictive probabilities, their uncertainty or combining both information. The proposed Bayesian kriging model is simple, and the proposed samping strategy represents a useful tool to address targeted infection control treatments and surbveillance campaigns. It is easily extendable to other fields of research. PMID:25131190

  15. Adapting the posterior probability of diagnosis index to enhance evidence-based screening: an application to ADHD in primary care.

    PubMed

    Lindhiem, Oliver; Yu, Lan; Grasso, Damion J; Kolko, David J; Youngstrom, Eric A

    2015-04-01

    This study adapts the Posterior Probability of Diagnosis (PPOD) Index for use with screening data. The original PPOD Index, designed for use in the context of comprehensive diagnostic assessments, is overconfident when applied to screening data. To correct for this overconfidence, we describe a simple method for adjusting the PPOD Index to improve its calibration when used for screening. Specifically, we compare the adjusted PPOD Index to the original index and naïve Bayes probability estimates on two dimensions of accuracy, discrimination and calibration, using a clinical sample of children and adolescents (N = 321) whose caregivers completed the Vanderbilt Assessment Scale to screen for attention-deficit/hyperactivity disorder and who subsequently completed a comprehensive diagnostic assessment. Results indicated that the adjusted PPOD Index, original PPOD Index, and naïve Bayes probability estimates are comparable using traditional measures of accuracy (sensitivity, specificity, and area under the curve), but the adjusted PPOD Index showed superior calibration. We discuss the importance of calibration for screening and diagnostic support tools when applied to individual patients. PMID:25000935

  16. Bayesian sensitivity analysis for posterior probability inferences in landslide hazard modeling

    NASA Astrophysics Data System (ADS)

    Cosmin Sandric, Ionut; Chitu, Zenaida

    2013-04-01

    Landslides hazard modeling implies assumptions on prior conditional density functions of predisposing and triggering factors. The model uses beta distribution to calculate the prior and conditional probability density functions for landslides triggering factors. The landslides triggering factor is considered the soil water content. The model takes into consideration the seasonal changes in vegetation interception and runoff derived from Landsat satellite images (Landsat MSS, TM, ETM+). The satellite images were downloaded from http://earthexplorer.usgs.gov website with no regard to cloud cover. All the images were bulk processed for radiance and reflectance the LAI index for each image was extracted and used in the interception model and maximum likelihood algorithm was applied for vegetation delineation and classification, used in evapotranspiration model. The soil water content was modeled for a period of 30 years, starting in 1975 and ending in 2005, in the Breaza administrative area and Panatau administrative area, located in the Curvature Subcarpathians. For each landslide occurred in this time frame the modeled soil water content was retained and further statistical analysis were conducted

  17. Interpretation of laboratory tests using a programmable hand-held calculator: calculation of posterior probability and relative risk on the basis of prior probability and sensitivity, specificity and result of the test.

    PubMed

    van de Merwe, J P

    1984-01-01

    A program is presented for the Hewlett-Packard HP- 41C programmable hand-held calculator that calculates the posterior probability and relative risk of an event (e.g. a disease) on the basis of prior probability (prevalence) and sensitivity, specificity and result of the test. PMID:6370577

  18. Accurate measurement of the sticking time and sticking probability of Rb atoms on a polydimethylsiloxane coating

    SciTech Connect

    Atutov, S. N. Plekhanov, A. I.

    2015-01-15

    We present the results of a systematic study of Knudsen’s flow of Rb atoms in cylindrical capillary cells coated with a polydimethylsiloxane (PDMS) compound. The purpose of the investigation is to determine the characterization of the coating in terms of the sticking probability and sticking time of Rb on the two types of coating of high and medium viscosities. We report the measurement of the sticking probability of a Rb atom to the coating equal to 4.3 × 10{sup −5}, which corresponds to the number of bounces 2.3 × 10{sup 4} at room temperature. These parameters are the same for the two kinds of PDMS used. We find that at room temperature, the respective sticking times for high-viscosity and medium-viscosity PDMS are 22 ± 3 μs and 49 ± 6 μs. These sticking times are about million times larger than the sticking time derived from the surface Rb atom adsorption energy and temperature of the coating. A tentative explanation of this surprising result is proposed based on the bulk diffusion of the atoms that collide with the surface and penetrate inside the coating. The results can be important in many resonance cell experiments, such as the efficient magnetooptical trapping of rare elements or radioactive isotopes and in experiments on the light-induced drift effect.

  19. Fast and accurate probability density estimation in large high dimensional astronomical datasets

    NASA Astrophysics Data System (ADS)

    Gupta, Pramod; Connolly, Andrew J.; Gardner, Jeffrey P.

    2015-01-01

    Astronomical surveys will generate measurements of hundreds of attributes (e.g. color, size, shape) on hundreds of millions of sources. Analyzing these large, high dimensional data sets will require efficient algorithms for data analysis. An example of this is probability density estimation that is at the heart of many classification problems such as the separation of stars and quasars based on their colors. Popular density estimation techniques use binning or kernel density estimation. Kernel density estimation has a small memory footprint but often requires large computational resources. Binning has small computational requirements but usually binning is implemented with multi-dimensional arrays which leads to memory requirements which scale exponentially with the number of dimensions. Hence both techniques do not scale well to large data sets in high dimensions. We present an alternative approach of binning implemented with hash tables (BASH tables). This approach uses the sparseness of data in the high dimensional space to ensure that the memory requirements are small. However hashing requires some extra computation so a priori it is not clear if the reduction in memory requirements will lead to increased computational requirements. Through an implementation of BASH tables in C++ we show that the additional computational requirements of hashing are negligible. Hence this approach has small memory and computational requirements. We apply our density estimation technique to photometric selection of quasars using non-parametric Bayesian classification and show that the accuracy of the classification is same as the accuracy of earlier approaches. Since the BASH table approach is one to three orders of magnitude faster than the earlier approaches it may be useful in various other applications of density estimation in astrostatistics.

  20. A three-step Maximum-A-Posterior probability method for InSAR data inversion of coseismic rupture with application to four recent large earthquakes in Asia

    NASA Astrophysics Data System (ADS)

    Sun, J.; Shen, Z.; Burgmann, R.; Liang, F.

    2012-12-01

    We develop a three-step Maximum-A-Posterior probability (MAP) method for coseismic rupture inversion, which aims at maximizing the a posterior probability density function (PDF) of elastic solutions of earthquake rupture. The method originates from the Fully Bayesian Inversion (FBI) and the Mixed linear-nonlinear Bayesian inversion (MBI) methods , shares the same a posterior PDF with them and keeps most of their merits, while overcoming its convergence difficulty when large numbers of low quality data are used and improving the convergence rate greatly using optimization procedures. A highly efficient global optimization algorithm, Adaptive Simulated Annealing (ASA), is used to search for the maximum posterior probability in the first step. The non-slip parameters are determined by the global optimization method, and the slip parameters are inverted for using the least squares method without positivity constraint initially, and then damped to physically reasonable range. This step MAP inversion brings the inversion close to 'true' solution quickly and jumps over local maximum regions in high-dimensional parameter space. The second step inversion approaches the 'true' solution further with positivity constraints subsequently applied on slip parameters using the Monte Carlo Inversion (MCI) technique, with all parameters obtained from step one as the initial solution. Then the slip artifacts are eliminated from slip models in the third step MAP inversion with fault geometry parameters fixed. We first used a designed model with 45 degree dipping angle and oblique slip, and corresponding synthetic InSAR data sets to validate the efficiency and accuracy of method. We then applied the method on four recent large earthquakes in Asia, namely the 2010 Yushu, China earthquake, the 2011 Burma earthquake, the 2011 New Zealand earthquake and the 2008 Qinghai, China earthquake, and compared our results with those results from other groups. Our results show the effectiveness of the method in earthquake studies and a number of advantages of it over other methods. The details will be reported on the meeting.

  1. Prestack inversion based on anisotropic Markov random field-maximum posterior probability inversion and its application to identify shale gas sweet spots

    NASA Astrophysics Data System (ADS)

    Wang, Kang-Ning; Sun, Zan-Dong; Dong, Ning

    2015-12-01

    Economic shale gas production requires hydraulic fracture stimulation to increase the formation permeability. Hydraulic fracturing strongly depends on geomechanical parameters such as Young's modulus and Poisson's ratio. Fracture-prone sweet spots can be predicted by prestack inversion, which is an ill-posed problem; thus, regularization is needed to obtain unique and stable solutions. To characterize gas-bearing shale sedimentary bodies, elastic parameter variations are regarded as an anisotropic Markov random field. Bayesian statistics are adopted for transforming prestack inversion to the maximum posterior probability. Two energy functions for the lateral and vertical directions are used to describe the distribution, and the expectation-maximization algorithm is used to estimate the hyperparameters of the prior probability of elastic parameters. Finally, the inversion yields clear geological boundaries, high vertical resolution, and reasonable lateral continuity using the conjugate gradient method to minimize the objective function. Antinoise and imaging ability of the method were tested using synthetic and real data.

  2. Adapting the Posterior Probability of Diagnosis (PPOD) Index to Enhance Evidence-Based Screening: An Application to ADHD in Primary Care

    PubMed Central

    Lindhiem, Oliver; Yu, Lan; Grasso, Damion J.; Kolko, David J.; Youngstrom, Eric A.

    2014-01-01

    This study adapts the Posterior Probability of Diagnosis (PPOD) Index for use with screening data. The original PPOD Index, designed for use in the context of comprehensive diagnostic assessments, is overconfident when applied to screening data. To correct for this overconfidence, we describe a simple method for adjusting the PPOD Index to improve its calibration when used for screening. Specifically, we compare the adjusted PPOD Index to the original index and Naïve Bayes probability estimates on two dimensions of accuracy, discrimination and calibration, using a clinical sample of children and adolescents (N = 321) whose caregivers completed the Vanderbilt Assessment Scale to screen for Attention-Deficit/Hyperactivity Disorder (ADHD) and who subsequently completed a comprehensive diagnostic assessment. Results indicated that the adjusted PPOD Index, original PPOD Index, and Naïve Bayes probability estimates are comparable using traditional measures of accuracy (sensitivity, specificity, AUC) but the adjusted PPOD Index showed superior calibration. We discuss the importance of calibration for screening and diagnostic support tools when applied to individual patients. PMID:25000935

  3. Assessing Goodness of Fit in Item Response Theory with Nonparametric Models: A Comparison of Posterior Probabilities and Kernel-Smoothing Approaches

    ERIC Educational Resources Information Center

    Sueiro, Manuel J.; Abad, Francisco J.

    2011-01-01

    The distance between nonparametric and parametric item characteristic curves has been proposed as an index of goodness of fit in item response theory in the form of a root integrated squared error index. This article proposes to use the posterior distribution of the latent trait as the nonparametric model and compares the performance of an index…

  4. A two-stage fast Bayesian spectral density approach for ambient modal analysis. Part I: Posterior most probable value and uncertainty

    NASA Astrophysics Data System (ADS)

    Yan, Wang-Ji; Katafygiotis, Lambros S.

    2015-03-01

    A two-stage fast Bayesian spectral density approach is proposed in this study to extract modal properties for the cases of separated modes and closely spaced modes. A novel technique for variable separation is developed so that the interaction between spectrum variables (i.e., frequency, damping ratio as well as the spectral density of modal excitation and prediction error) and spatial variables (i.e., mode shape components) can be decoupled completely for both cases. In a first stage, the spectrum variables can be identified through a so-called 'fast Bayesian spectral trace approach' (FBSTA) by employing the statistical properties of the sum of auto-spectral density, while the spatial variables can be estimated in a follow up second stage through 'fast Bayesian spectral density approach' (FBSDA) by using the statistical information of the entire spectral density matrix. This study also reveals the intrinsic relationship between FBSDA and 'fast Bayesian FFT approach' formulated recently when multiple sets of measurements are available. The newly developed two-stage Bayesian approach allows for a fast computation of the most probable values and covariance matrix of modal properties. The companion paper is devoted to assembling the local mode shape components corresponding to different setups to form the overall mode shapes using a Bayesian statistical framework and verifying the proposed algorithms through simulated and field testing data.

  5. A Posteriori Transit Probabilities

    NASA Astrophysics Data System (ADS)

    Stevens, Daniel J.; Gaudi, B. Scott

    2013-08-01

    Given the radial velocity (RV) detection of an unseen companion, it is often of interest to estimate the probability that the companion also transits the primary star. Typically, one assumes a uniform distribution for the cosine of the inclination angle i of the companion's orbit. This yields the familiar estimate for the prior transit probability of ~Rlowast/a, given the primary radius Rlowast and orbital semimajor axis a, and assuming small companions and a circular orbit. However, the posterior transit probability depends not only on the prior probability distribution of i but also on the prior probability distribution of the companion mass Mc, given a measurement of the product of the two (the minimum mass Mc sin i) from an RV signal. In general, the posterior can be larger or smaller than the prior transit probability. We derive analytic expressions for the posterior transit probability assuming a power-law form for the distribution of true masses, dΓ/dMcvpropMcα, for integer values -3 <= α <= 3. We show that for low transit probabilities, these probabilities reduce to a constant multiplicative factor fα of the corresponding prior transit probability, where fα in general depends on α and an assumed upper limit on the true mass. The prior and posterior probabilities are equal for α = -1. The posterior transit probability is ~1.5 times larger than the prior for α = -3 and is ~4/π times larger for α = -2, but is less than the prior for α>=0, and can be arbitrarily small for α > 1. We also calculate the posterior transit probability in different mass regimes for two physically-motivated mass distributions of companions around Sun-like stars. We find that for Jupiter-mass planets, the posterior transit probability is roughly equal to the prior probability, whereas the posterior is likely higher for Super-Earths and Neptunes (10 M⊕ - 30 M⊕) and Super-Jupiters (3 MJup - 10 MJup), owing to the predicted steep rise in the mass function toward smaller masses in these regimes. We therefore suggest that companions with minimum masses in these regimes might be better-than-expected targets for transit follow-up, and we identify promising targets from RV-detected planets in the literature. Finally, we consider the uncertainty in the transit probability arising from uncertainties in the input parameters, and the effect of ignoring the dependence of the transit probability on the true semimajor axis on i.

  6. Posterior sampling with improved efficiency

    SciTech Connect

    Hanson, K.M.; Cunningham, G.S.

    1998-12-01

    The Markov Chain Monte Carlo (MCMC) technique provides a means to generate a random sequence of model realizations that sample the posterior probability distribution of a Bayesian analysis. That sequence may be used to make inferences about the model uncertainties that derive from measurement uncertainties. This paper presents an approach to improving the efficiency of the Metropolis approach to MCMC by incorporating an approximation to the covariance matrix of the posterior distribution. The covariance matrix is approximated using the update formula from the BFGS quasi-Newton optimization algorithm. Examples are given for uncorrelated and correlated multidimensional Gaussian posterior distributions.

  7. Normal Tissue Complication Probability Estimation by the Lyman-Kutcher-Burman Method Does Not Accurately Predict Spinal Cord Tolerance to Stereotactic Radiosurgery

    SciTech Connect

    Daly, Megan E.; Luxton, Gary; Choi, Clara Y.H.; Gibbs, Iris C.; Chang, Steven D.; Adler, John R.; Soltys, Scott G.

    2012-04-01

    Purpose: To determine whether normal tissue complication probability (NTCP) analyses of the human spinal cord by use of the Lyman-Kutcher-Burman (LKB) model, supplemented by linear-quadratic modeling to account for the effect of fractionation, predict the risk of myelopathy from stereotactic radiosurgery (SRS). Methods and Materials: From November 2001 to July 2008, 24 spinal hemangioblastomas in 17 patients were treated with SRS. Of the tumors, 17 received 1 fraction with a median dose of 20 Gy (range, 18-30 Gy) and 7 received 20 to 25 Gy in 2 or 3 sessions, with cord maximum doses of 22.7 Gy (range, 17.8-30.9 Gy) and 22.0 Gy (range, 20.2-26.6 Gy), respectively. By use of conventional values for {alpha}/{beta}, volume parameter n, 50% complication probability dose TD{sub 50}, and inverse slope parameter m, a computationally simplified implementation of the LKB model was used to calculate the biologically equivalent uniform dose and NTCP for each treatment. Exploratory calculations were performed with alternate values of {alpha}/{beta} and n. Results: In this study 1 case (4%) of myelopathy occurred. The LKB model using radiobiological parameters from Emami and the logistic model with parameters from Schultheiss overestimated complication rates, predicting 13 complications (54%) and 18 complications (75%), respectively. An increase in the volume parameter (n), to assume greater parallel organization, improved the predictive value of the models. Maximum-likelihood LKB fitting of {alpha}/{beta} and n yielded better predictions (0.7 complications), with n = 0.023 and {alpha}/{beta} = 17.8 Gy. Conclusions: The spinal cord tolerance to the dosimetry of SRS is higher than predicted by the LKB model using any set of accepted parameters. Only a high {alpha}/{beta} value in the LKB model and only a large volume effect in the logistic model with Schultheiss data could explain the low number of complications observed. This finding emphasizes that radiobiological models traditionally used to estimate spinal cord NTCP may not apply to the dosimetry of SRS. Further research with additional NTCP models is needed.

  8. ModEnzA: Accurate Identification of Metabolic Enzymes Using Function Specific Profile HMMs with Optimised Discrimination Threshold and Modified Emission Probabilities

    PubMed Central

    Desai, Dhwani K.; Nandi, Soumyadeep; Srivastava, Prashant K.; Lynn, Andrew M.

    2011-01-01

    Various enzyme identification protocols involving homology transfer by sequence-sequence or profile-sequence comparisons have been devised which utilise Swiss-Prot sequences associated with EC numbers as the training set. A profile HMM constructed for a particular EC number might select sequences which perform a different enzymatic function due to the presence of certain fold-specific residues which are conserved in enzymes sharing a common fold. We describe a protocol, ModEnzA (HMM-ModE Enzyme Annotation), which generates profile HMMs highly specific at a functional level as defined by the EC numbers by incorporating information from negative training sequences. We enrich the training dataset by mining sequences from the NCBI Non-Redundant database for increased sensitivity. We compare our method with other enzyme identification methods, both for assigning EC numbers to a genome as well as identifying protein sequences associated with an enzymatic activity. We report a sensitivity of 88% and specificity of 95% in identifying EC numbers and annotating enzymatic sequences from the E. coli genome which is higher than any other method. With the next-generation sequencing methods producing a huge amount of sequence data, the development and use of fully automated yet accurate protocols such as ModEnzA is warranted for rapid annotation of newly sequenced genomes and metagenomic sequences. PMID:21541071

  9. [Posterior knee instability].

    PubMed

    Hoffman, F

    2004-01-01

    Due to improved diagnostic methods, posterior knee instabilities are detected more often. Up to now, however, the natural history of isolated ruptures of the posterior cruciate ligament is not known exactly. After conservative treatment, the first degenerative changes occur after about 10-15 years, mainly in the femoropatellar joint and the medial compartment. In complex posterior instabilities with lesions of the secondary stabilizers, the posterolateral structures, the lateral collateral ligament, and the leg alignment play an important role. Conservative or operative treatment of posterior knee instabilities depends on the extent of the lesion, the violated structures, and the impairment of the patient. For replacement of the posterior cruciate ligament, grafts from the patella ligament, the quadriceps tendon, and the hamstrings are used most frequently. In simultaneous lesions of the posterolateral corner of the knee joint, additional ligament-stabilizing methods are necessary. PMID:14994754

  10. Congenital basis of posterior fossa anomalies.

    PubMed

    Cotes, Claudia; Bonfante, Eliana; Lazor, Jillian; Jadhav, Siddharth; Caldas, Maria; Swischuk, Leonard; Riascos, Roy

    2015-06-01

    The classification of posterior fossa congenital anomalies has been a controversial topic. Advances in genetics and imaging have allowed a better understanding of the embryologic development of these abnormalities. A new classification schema correlates the embryologic, morphologic, and genetic bases of these anomalies in order to better distinguish and describe them. Although they provide a better understanding of the clinical aspects and genetics of these disorders, it is crucial for the radiologist to be able to diagnose the congenital posterior fossa anomalies based on their morphology, since neuroimaging is usually the initial step when these disorders are suspected. We divide the most common posterior fossa congenital anomalies into two groups: 1) hindbrain malformations, including diseases with cerebellar or vermian agenesis, aplasia or hypoplasia and cystic posterior fossa anomalies; and 2) cranial vault malformations. In addition, we will review the embryologic development of the posterior fossa and, from the perspective of embryonic development, will describe the imaging appearance of congenital posterior fossa anomalies. Knowledge of the developmental bases of these malformations facilitates detection of the morphological changes identified on imaging, allowing accurate differentiation and diagnosis of congenital posterior fossa anomalies. PMID:26246090

  11. Radiographic assessment of posterior malleolar ankle fractures.

    PubMed

    Gonzalez, Olga; Fleming, Justin J; Meyr, Andrew J

    2015-01-01

    The anatomy of the posterior tibial malleolus plays an important role in the structure and function of the ankle mortise. With specific respect to ankle fractures, the presence, size, and displacement of posterior malleolar fractures (Volkmann's fracture) helps determine which will be amendable to operative fixation. The objective of the present study was to increase the body of knowledge with respect to the ability of foot and ankle reconstructive surgeons to assess posterior malleolar ankle fractures using plain film radiography. Three different variables were investigated on Sawbones() models: (1) differing size of posterior malleolar fractures (10%, 25%, and 50% of the tibial plafond), (2) differing displacement of posterior malleolar fractures (0 and 5 mm of proximal displacement), and (3) 2 different radiographic projections (standard lateral and externally rotated lateral projections). Accurate identification of the posterior malleolar fracture occurred on 86.67% (26 of 30) of standard lateral radiographs and 100% (30 of 30) of externally rotated lateral radiographs. Furthermore, the surgeons described the fracture with greater precision and had greater interclass correlation coefficient values with respect to measurement of sagittal plane displacement (0.977 versus 0.939) and percentage of involvement of the tibial plafond (0.972 versus 0.775) with an externally rotated lateral projection compared with a standard lateral projection. Our results provide evidence that an externally rotated lateral radiographic projection can provide surgeons with some additional information with respect to the presence, size, and displacement of posterior malleolar ankle fractures. PMID:25262838

  12. Posterior lumbar interbody fusion.

    PubMed

    DiPaola, Christian P; Molinari, Robert W

    2008-03-01

    Posterior lumbar interbody fusion (PLIF) and transforaminal lumbar interbody fusion (TLIF) create intervertebral fusion by means of a posterior approach. Both techniques are useful in managing degenerative disk disease, severe instability, spondylolisthesis, deformity, and pseudarthrosis. Successful results have been reported with allograft, various cages (for interbody support), autograft, and recombinant human bone morphogenetic protein-2. Interbody fusion techniques may facilitate reduction and enhance fusion. The rationale for PLIF and TLIF is biomechanically sound. However, clinical outcomes of different anterior and posterior spinal fusion techniques tend to be similar. PLIF has a high complication rate (dural tear, 5.4% to 10%; neurologic injury, 9% to 16%). These findings, coupled with the versatility of TLIF throughout the entire lumbar spine, may make TLIF the ideal choice for an all-posterior interbody fusion. PMID:18316711

  13. Fast Bayesian approach for modal identification using free vibration data, Part II-Posterior uncertainty and application

    NASA Astrophysics Data System (ADS)

    Ni, Yan-Chun; Zhang, Feng-Liang; Lam, Heung-Fai; Au, Siu-Kui

    2016-03-01

    A Bayesian statistical framework has been developed for modal identification using free vibration data in the companion paper (Zhang et al., Mech. Syst. Sig. Process. (2015)). Efficient strategies have been developed for evaluating the most probable value (MPV) of the modal parameters in both well-separated mode and general multiple mode cases. This paper investigates the posterior uncertainty of the modal parameters in terms of their posterior covariance matrix, which is mathematically equal to the inverse of the Hessian of the negative log-likelihood function (NLLF) evaluated at the MPVs. Computational issues associated with the determination of the posterior covariance matrix are discussed. Analytical expressions are derived for the Hessian so that it can be evaluated accurately and efficiently without resorting to finite difference method. The proposed methods are verified with synthetic data and then applied to field vibration test data.

  14. Posterior leukoencephalopathy syndrome.

    PubMed

    Garg, R K

    2001-01-01

    Posterior leukoencephalopathy syndrome is a newly recognised brain disorder that predominantly affects the cerebral white matter. Oedematous lesions particularly involve the posterior parietal and occipital lobes, and may spread to basal ganglia, brain stem, and cerebellum. This rapidly evolving neurological condition is clinically characterised by headache, nausea and vomiting, seizures, visual disturbances, altered sensorium, and occasionally focal neurological deficit. Posterior leukoencephalopathy syndrome is often associated with an abrupt increase in blood pressure and is usually seen in patients with eclampsia, renal disease, and hypertensive encephalopathy. It is also seen in the patients treated with cytotoxic and immunosuppressive drugs such as cyclosporin, tacrolimus, and interferon alfa. The lesions of posterior leukoencephalopathy are best visualised with magnetic resonance (MR) imaging. T2 weighted MR images, at the height of symptoms, characteristically show diffuse hyperintensity selectively involving the parieto-occipital white matter. Occasionally the lesions also involve the grey matter. Computed tomography can also be used satisfactorily to detect hypodense lesions of posterior leukoencephalopathy. Early recognition of this condition is of paramount importance because prompt control of blood pressure or withdrawal of immunosuppressive agents will cause reversal of the syndrome. Delay in the diagnosis and treatment can result in permanent damage to affected brain tissues. PMID:11123390

  15. Posterior interosseous neuropathy: electrodiagnostic evaluation.

    PubMed

    Bevelaqua, Anna-Christina; Hayter, Catherine L; Feinberg, Joseph H; Rodeo, Scott A

    2012-07-01

    Electrodiagnostic studies are used to anatomically localize nerve injuries. These tests help differentiate between cervical radiculopathies, brachial plexopathies, and peripheral nerve injuries. They also help to identify or rule out other underlying neurological diseases and disorders. In this case report, a 22-year-old male swimmer presented with left finger extensor weakness following pull-up exercises. Left wrist extension remained intact. Electrodiagnostic testing revealed a severe but incomplete posterior interosseous neuropathy. Magnetic resonance imaging confirmed inflammation of the nerve in the forearm. Posterior interosseous neuropathy is an uncommon but well-studied condition. Typically, this condition presents with weakness in finger and thumb extension with preserved wrist extension as the extensor carpi radialis longus is innervated proximal to the site of nerve compression in most cases. It is important to understand the anatomic course and distribution of the radial nerve in order to make an accurate diagnosis. Once the anatomy is understood, electrodiagnostic testing may be used to identify the location of nerve injury and exclude other disorders. PMID:23874261

  16. Tibialis Posterior Tendon Entrapment Within Posterior Malleolar Fracture Fragment.

    PubMed

    Fantry, Amanda; Lareau, Craig; Vopat, Bryan; Blankenhorn, Brad

    2016-01-01

    Management of posterior malleolus fractures continues to be controversial, with respect to both need for fixation and fixation methods. Fixation methods include an open posterior approach to the ankle as well as percutaneous reduction and fixation with or without arthroscopy for visualization of the articular surface. Plain radiographs are unreliable in identifying fracture pattern and intraoperative reduction, making arthroscopy a valuable adjunct to posterior malleolus fracture management. In this article, we report a case of tibialis posterior tendon entrapment within a posterior malleolus fracture, as identified by arthroscopy and managed with open reduction. Tibialis posterior tendon entrapment within a posterior malleolus has not been previously reported. Ankle arthroscopy for posterior malleolus fractures provides an opportunity to identify soft-tissue or tendinous entrapment, articular surface reduction, and articular cartilage injuries unlikely to be identified with fluoroscopy alone and should be considered in reduction and fixation of posterior malleolus fractures. PMID:26991573

  17. Bayesian inference of a lake water quality model by emulating its posterior density

    NASA Astrophysics Data System (ADS)

    Dietzel, A.; Reichert, P.

    2014-10-01

    We use a Gaussian stochastic process emulator to interpolate the posterior probability density of a computationally demanding application of the biogeochemical-ecological lake model BELAMO to accelerate statistical inference of deterministic model and error model parameters. The deterministic model consists of a mechanistic description of key processes influencing the mass balance of nutrients, dissolved oxygen, organic particles, and phytoplankton and zooplankton in the lake. This model is complemented by a Gaussian stochastic process to describe the remaining model bias and by Normal, independent observation errors. A small subsample of the Markov chain representing the posterior of the model parameters is propagated through the full model to get model predictions and uncertainty estimates. We expect this approximation to be more accurate at only slightly higher computational costs compared to using a Normal approximation to the posterior probability density and linear error propagation to the results as we did in an earlier paper. The performance of the two techniques is compared for a didactical example as well as for the lake model. As expected, for the didactical example, the use of the emulator led to posterior marginals of the model parameters that are closer to those calculated by Markov chain simulation using the full model than those based on the Normal approximation. For the lake model, the new technique proved applicable without an excessive increase in computational requirements, but we faced challenges in the choice of the design data set for emulator calibration. As the posterior is a scalar function of the parameters, the suggested technique is an alternative to the emulation of a potentially more complex, structured output of the simulation model that allows for the use of a less case-specific emulator. This is at the cost that still the full model has to be used for prediction (which can be done with a smaller, approximately independent subsample of the Markov chain).

  18. An Alternative Version of Conditional Probabilities and Bayes' Rule: An Application of Probability Logic

    ERIC Educational Resources Information Center

    Satake, Eiki; Amato, Philip P.

    2008-01-01

    This paper presents an alternative version of formulas of conditional probabilities and Bayes' rule that demonstrate how the truth table of elementary mathematical logic applies to the derivations of the conditional probabilities of various complex, compound statements. This new approach is used to calculate the prior and posterior probabilities

  19. Posterior cruciate ligament (PCL) injury

    MedlinePlus

    Cruciate ligament injury - posterior; PCL injury; Knee injury - posterior cruciate ligament (PCL); Hyperextended knee ... physical examination to check for signs of PCL injury. This includes moving the knee joint in various ...

  20. Posterior Urethral Strictures

    PubMed Central

    Gelman, Joel; Wisenbaugh, Eric S.

    2015-01-01

    Pelvic fracture urethral injuries are typically partial and more often complete disruptions of the most proximal bulbar and distal membranous urethra. Emergency management includes suprapubic tube placement. Subsequent primary realignment to place a urethral catheter remains a controversial topic, but what is not controversial is that when there is the development of a stricture (which is usually obliterative with a distraction defect) after suprapubic tube placement or urethral catheter removal, the standard of care is delayed urethral reconstruction with excision and primary anastomosis. This paper reviews the management of patients who suffer pelvic fracture urethral injuries and the techniques of preoperative urethral imaging and subsequent posterior urethroplasty. PMID:26691883

  1. Posterior Urethral Strictures.

    PubMed

    Gelman, Joel; Wisenbaugh, Eric S

    2015-01-01

    Pelvic fracture urethral injuries are typically partial and more often complete disruptions of the most proximal bulbar and distal membranous urethra. Emergency management includes suprapubic tube placement. Subsequent primary realignment to place a urethral catheter remains a controversial topic, but what is not controversial is that when there is the development of a stricture (which is usually obliterative with a distraction defect) after suprapubic tube placement or urethral catheter removal, the standard of care is delayed urethral reconstruction with excision and primary anastomosis. This paper reviews the management of patients who suffer pelvic fracture urethral injuries and the techniques of preoperative urethral imaging and subsequent posterior urethroplasty. PMID:26691883

  2. Novel posterior fixation keratoprosthesis

    NASA Astrophysics Data System (ADS)

    Lacombe, Emmanuel

    1992-08-01

    The keratoprosthesis is the last solution for corneally blind patients that cannot benefit from corneal transplants. Keratoprostheses that have been designed to be affixed anteriorly usually necessitate multi-step surgical procedures and are continuously subjected to the extrusion forces generated by the positive intraocular pressure; therefore, clinical results in patients prove inconsistent. We proposed a novel keratoprosthesis concept that utilizes posterior corneal fixation which `a priori' minimizes the risk of aqueous leakage and expulsion. This prosthesis is implanted in a single procedure thereby reducing the number of surgical complications normally associated with anterior fixation devices. In addition, its novel design makes this keratoprosthesis implantable in phakic eyes. With an average follow-up of 13 months (range 3 to 25 months), our results on 21 cases are encouraging. Half of the keratoprostheses were implanted in severe burn cases, with the remainder in cases of pseudo- pemphigus. Good visual results and cosmetic appearance were obtained in 14 of 21 eyes.

  3. An Alternative Version of Conditional Probabilities and Bayes' Rule: An Application of Probability Logic

    ERIC Educational Resources Information Center

    Satake, Eiki; Amato, Philip P.

    2008-01-01

    This paper presents an alternative version of formulas of conditional probabilities and Bayes' rule that demonstrate how the truth table of elementary mathematical logic applies to the derivations of the conditional probabilities of various complex, compound statements. This new approach is used to calculate the prior and posterior probabilities…

  4. Pig Data and Bayesian Inference on Multinomial Probabilities

    ERIC Educational Resources Information Center

    Kern, John C.

    2006-01-01

    Bayesian inference on multinomial probabilities is conducted based on data collected from the game Pass the Pigs[R]. Prior information on these probabilities is readily available from the instruction manual, and is easily incorporated in a Dirichlet prior. Posterior analysis of the scoring probabilities quantifies the discrepancy between empirical…

  5. Pig Data and Bayesian Inference on Multinomial Probabilities

    ERIC Educational Resources Information Center

    Kern, John C.

    2006-01-01

    Bayesian inference on multinomial probabilities is conducted based on data collected from the game Pass the Pigs[R]. Prior information on these probabilities is readily available from the instruction manual, and is easily incorporated in a Dirichlet prior. Posterior analysis of the scoring probabilities quantifies the discrepancy between empirical

  6. Primary posterior mediastinum hydatid cyst.

    PubMed

    Ahmed, Mughis Uddin; Eid, Ahmed Fathi; Al-Hawashim, Nadia; Sheikh, Mohammed Younus; Yiannakou, Nearchos

    2014-04-01

    Primary posterior mediastinal hydatid cyst is a serious health problem for the Mediterranean countries. We diagnosed a case of a 46-year-old female with a primary posterior mediastinum hydatid cyst on CT and MRI. It was provisionally identified as either a hydatid cyst or bronchogenic cyst or neuroenteric cyst. CT guided aspiration with 18 gauge needle confirmed as hydatid sand. This is very rare in this population but it should be kept in mind when one is looking at any cyst in the posterior mediastinum. PMID:24709247

  7. Spherical aberration of the anterior and posterior surfaces of the human cornea

    NASA Astrophysics Data System (ADS)

    Sicam, Victor Arni; Dubbelman, Michiel; van der Heijde, Rob G.

    2006-03-01

    A ray-tracing procedure was applied to corrected Scheimpflug photography measurements to determine the spherical aberration of the anterior and posterior surfaces of the cornea. It was found that the total spherical aberration of the cornea increases slightly with age. The spherical aberration of the posterior corneal surface is negative at a young age and becomes positive at an older age. To make an accurate description of the spherical aberration for the whole eye, the posterior surface must also be measured.

  8. Bayesian network using edge probabilities for target detection and recognition

    NASA Astrophysics Data System (ADS)

    Zhao, Renjian; Kelly, Patrick A.; Derin, Haluk

    2001-08-01

    It has been noted recently that, in a number of applications, effective approximations to complex posterior probabilities can be computed through the framework of probability propagation in Bayesian networks. In this paper, we develop a Bayesian network for the problem of target detection and recognition. Our multiply-connected Bayesian network is based on a distribution decomposition of the form p(y,t,e)=p(y|t,e)p(t|e)p(e), where y is an observed image, t is a set of target pixels together with identifying labels, and e is a set of edge pixels. Running a probability propagation algorithm on this network leads to an approximation of the desired posterior probability p(t|y) as a product of terms that correlate the conditional observation distribution p(y|t,e) and target distribution p(t|e) with a posterior edge distribution p(e|y). We describe approaches for generating the required posterior edge distribution and for calculating the correlations through template matching. The result is a computationally-efficient algorithm for computing posterior target probabilities that can be used either to generate hard decisions or for fusion with other information. Target detection based on the posterior probability p(t|y) is discussed in the paper.

  9. Minimally Invasive Posterior Cervical Foraminotomy.

    PubMed

    Ahn, Junyoung; Tabaraee, Ehsan; Bohl, Daniel D; Singh, Kern

    2015-10-01

    The minimally invasive posterior cervical foraminotomy procedure has become a common and successful procedure for the treatment of cervical radiculopathy. Specifically, the minimally invasive approach allows for decreased postoperative pain, blood loss, and length of hospitalization by preserving the surrounding soft tissue as compared with the traditional open approach. This article and accompanying video demonstrates the technique for a primary, single-level minimally invasive posterior cervical foraminotomy as performed through a tubular retractor. PMID:26322905

  10. Rethinking "posterior" tongue-tie.

    PubMed

    Douglas, Pamela Sylvia

    2013-12-01

    Currently, many clinicians who help with breastfeeding problems are diagnosing "posterior" tongue-tie in infants and performing or referring for frenotomy. In this "Speaking Out" article, I argue that the diagnosis of "posterior" tongue-tie has successfully raised awareness of the importance of impaired tongue function in breastfeeding difficulty. However, the diagnosis of "posterior" tongue-tie also applies a reductionist, medicalized theoretical frame to the complex problem of impaired tongue function, risking unintended outcomes. Impaired tongue function arises out of multiple interacting and co-evolving factors, including the interplay between social behaviors concerning breastfeeding and mother-infant biology. Consideration of theoretical frames is vital if we are to build an evidence base through efficient use of the scarce resources available for clinical breastfeeding research and minimize unintended outcomes. PMID:24143939

  11. Interstitial pressure measurements in the anterior and posterior compartments in athletes with shin splints.

    PubMed

    D'Ambrosia, R D; Zelis, R F; Chuinard, R G; Wilmore, J

    1977-01-01

    We found no basis for increased intercompartmental pressure in either the anterior or posterior compartments as the cause of shin splints. The pain in all 14 of the patients studied was localized to the posterior medial border of the tibia at the origin of the posterior tibial muscle, and evidence of periostitis in this area was seen in two of our patients, suggesting the possible tearing away of the posterior tibial muscle from its origin. Shin splints is a lay term which has assumed medical diagnostic significance and should be removed from common usage by more accurately localizing the focus of pain. PMID:871182

  12. Unsuccessful outcomes after posterior urethroplasty

    PubMed Central

    Engel, Oliver; Fisch, Margit

    2015-01-01

    Posterior urethroplasty is the most common strategy for the treatment of post-traumatic urethral injuries. Especially in younger patients, post-traumatic injuries are a common reason for urethral strictures caused by road traffic accidents, with pelvic fracture or direct trauma to the perineum. In many cases early endoscopic realignment is the first attempt to restore the junction between proximal and distal urethra, but in some cases primary realignment is not possible or not enough to treat the urethral injury. In these cases suprapubic cystostomy alone and delayed repair by stricture excision and posterior urethroplasty is an alternative procedure to minimise the risk of stricture recurrence. PMID:26019980

  13. Probability mapping of contaminants

    SciTech Connect

    Rautman, C.A.; Kaplan, P.G.; McGraw, M.A.; Istok, J.D.; Sigda, J.M.

    1994-04-01

    Exhaustive characterization of a contaminated site is a physical and practical impossibility. Descriptions of the nature, extent, and level of contamination, as well as decisions regarding proposed remediation activities, must be made in a state of uncertainty based upon limited physical sampling. The probability mapping approach illustrated in this paper appears to offer site operators a reasonable, quantitative methodology for many environmental remediation decisions and allows evaluation of the risk associated with those decisions. For example, output from this approach can be used in quantitative, cost-based decision models for evaluating possible site characterization and/or remediation plans, resulting in selection of the risk-adjusted, least-cost alternative. The methodology is completely general, and the techniques are applicable to a wide variety of environmental restoration projects. The probability-mapping approach is illustrated by application to a contaminated site at the former DOE Feed Materials Production Center near Fernald, Ohio. Soil geochemical data, collected as part of the Uranium-in-Soils Integrated Demonstration Project, have been used to construct a number of geostatistical simulations of potential contamination for parcels approximately the size of a selective remediation unit (the 3-m width of a bulldozer blade). Each such simulation accurately reflects the actual measured sample values, and reproduces the univariate statistics and spatial character of the extant data. Post-processing of a large number of these equally likely statistically similar images produces maps directly showing the probability of exceeding specified levels of contamination (potential clean-up or personnel-hazard thresholds).

  14. Bladder neck incompetence at posterior urethroplasty

    PubMed Central

    Koraitim, Mamdouh M.

    2015-01-01

    The finding of an incompetent bladder neck (BN) at the time of posterior urethroplasty will necessarily exacerbate the already difficult situation. In such cases the aim of the treatment is not only to restore urethral continuity by end-to-end urethral anastomosis, but also to restore the function of the BN to maintain urinary continence. Fortunately, the incidence of incompetence of the BN at posterior urethroplasty is uncommon, usually ?4.5%. It seems that pelvic fracture-related BN injuries, in contrast to urethral injuries which result from a shearing force, are due to direct injury by the sharp edge of the fractured and displaced pubic bone. The risk of injuries to the BN is greater in children, in patients with a fracture involving both superior and inferior pubic rami on the same side, and in those managed initially by primary realignment. An incompetent BN is suspected by finding an open rectangular BN on cystography, and a fixedly open BN on suprapubic cystoscopy. An incompetent BN can be treated either subsequent to or concomitant with the urethral repair, according to whether a perineal or a perineo-abdominal urethroplasty is used, respectively. Several options have been reported to treat pelvic fracture-related BN incompetence, including reconstructing the BN, forming a new sphincter by tubularisation of a rectangular flap of the anterior bladder wall, and mechanical occlusion by an artificial sphincter or collagen injection. Reconstruction of the BN by the Young-Dees-Leadbetter?? procedure probably provides the most successful results. PMID:26019982

  15. The neuropsychiatric profile of posterior cortical atrophy.

    PubMed

    Isella, Valeria; Villa, Giulia; Mapelli, Cristina; Ferri, Francesca; Appollonio, Ildebrando Marco; Ferrarese, Carlo

    2015-06-01

    We analyzed scores obtained at the Neuropsychiatric Inventory (NPI) by 20 patients with posterior cortical atrophy (PCA) and contrasted it with 20 patients having Alzheimer disease (AD). Patients with hallucinations and delusions were not included due to the high probability of a diagnosis of Lewy body disease. Prevalence of behavioral and psychological symptoms (BPSD) was 95% in the PCA group, the most frequent being apathy and anxiety. Cluster analysis on NPI subscales highlighted a behavioral subsyndrome characterized by agitated temper and irritability. Depression, anxiety, and apathy did not cluster with any other BPSD nor with each other. The PCA group showed a significantly higher proportion of anxious patients and worse anxiety score than patients with AD. No correlation was found between NPI data and demographic, clinical, or neuropsychological features nor were there significant differences for the same variables between anxious and nonanxious cases with PCA. In agreement with anecdotal reports, anxiety seems particularly relevant in PCA. PMID:25330926

  16. Multinomial mixture model with heterogeneous classification probabilities

    USGS Publications Warehouse

    Holland, M.D.; Gray, B.R.

    2011-01-01

    Royle and Link (Ecology 86(9):2505-2512, 2005) proposed an analytical method that allowed estimation of multinomial distribution parameters and classification probabilities from categorical data measured with error. While useful, we demonstrate algebraically and by simulations that this method yields biased multinomial parameter estimates when the probabilities of correct category classifications vary among sampling units. We address this shortcoming by treating these probabilities as logit-normal random variables within a Bayesian framework. We use Markov chain Monte Carlo to compute Bayes estimates from a simulated sample from the posterior distribution. Based on simulations, this elaborated Royle-Link model yields nearly unbiased estimates of multinomial and correct classification probability estimates when classification probabilities are allowed to vary according to the normal distribution on the logit scale or according to the Beta distribution. The method is illustrated using categorical submersed aquatic vegetation data. ?? 2010 Springer Science+Business Media, LLC.

  17. Stereolithography for Posterior Fossa Cranioplasty

    PubMed Central

    Agner, Celso; Dujovny, Manuel; Evenhouse, Raymond; Charbel, Fady T.; Sadler, Lewis

    1998-01-01

    Posterior fossa cranioplasty has been suggested for improvement of neurological symptoms following craniectomy. However, there is no particular recommendation in the literature about techniques for prosthesis manufacture and implantation. We report our experience using rapid prototyping technology and stereolithography for pre-surgical implant design and production of cranioplasties. ImagesFigure 1Figure 2Figure 3Figure 4Figure 5 PMID:17171056

  18. Posterior Tibial Tendon Dysfunction (PTTD)

    MedlinePlus

    ... ACFAS | Información en Español Advanced Search Home » Foot & Ankle Conditions » Posterior Tibial Tendon Dysfunction (PTTD) Text Size ... the arch, and an inward rolling of the ankle. As the condition progresses, the symptoms will change. ...

  19. Accuracy of posterior subtalar joint injection without fluoroscopy.

    PubMed

    Kirk, Kevin L; Campbell, John T; Guyton, Gregory P; Schon, Lew C

    2008-11-01

    Injection into the posterior subtalar joint has not been validated for accuracy using radiographic end points. We asked whether needle placement into a normal posterior subtalar joint could be performed accurately and selectively by experienced surgeons without fluoroscopic guidance. Three fellowship-trained orthopaedic foot and ankle surgeons each injected the posterior subtalar joint of 20 cadaveric specimens using an anterolateral approach. Fluoroscopic images were obtained by an independent investigator and blinded. A separate fellowship-trained foot and ankle surgeon interpreted the images. Of 60 injections, 58 were accurate and two were extraarticular based on interpretation by an independent foot and ankle surgeon. Extravasation into the ankle occurred in 14 samples and into the peroneal sheath in two samples. Experienced surgeons can place intraarticular injections into a radiographically normal posterior subtalar joint without fluoroscopy with a high degree of accuracy. However, extravasation into the ankle or peroneal tendon sheath occurred in an unpredictable fashion, suggesting selectivity of injection placement is relatively limited without the use of fluoroscopy. Fluoroscopy may not be necessary for injections used solely for therapeutic purposes. However, if the injection is intended for diagnostic purposes or to assist in surgical decision-making or if the joint is abnormal, we recommend fluoroscopy to ensure the subtalar joint is the only anatomic structure impacted by the injection. PMID:18404293

  20. Probability 1/e

    ERIC Educational Resources Information Center

    Koo, Reginald; Jones, Martin L.

    2011-01-01

    Quite a number of interesting problems in probability feature an event with probability equal to 1/e. This article discusses three such problems and attempts to explain why this probability occurs with such frequency.

  1. Probability distributions for multimeric systems.

    PubMed

    Albert, Jaroslav; Rooman, Marianne

    2016-01-01

    We propose a fast and accurate method of obtaining the equilibrium mono-modal joint probability distributions for multimeric systems. The method necessitates only two assumptions: the copy number of all species of molecule may be treated as continuous; and, the probability density functions (pdf) are well-approximated by multivariate skew normal distributions (MSND). Starting from the master equation, we convert the problem into a set of equations for the statistical moments which are then expressed in terms of the parameters intrinsic to the MSND. Using an optimization package on Mathematica, we minimize a Euclidian distance function comprising of a sum of the squared difference between the left and the right hand sides of these equations. Comparison of results obtained via our method with those rendered by the Gillespie algorithm demonstrates our method to be highly accurate as well as efficient. PMID:25840518

  2. Pediatric Posterior Sternoclavicular Joint Injuries.

    PubMed

    Chaudhry, Sonia

    2015-08-01

    Posterior sternoclavicular joint injuries are increasingly diagnosed in children and young adults. Most of these injuries are the result of indirect mechanisms, typically lateral compression, with a posterior-to-anterior force applied to the shoulder during sports. Less frequently, these injuries are caused by direct impact on the medial clavicle, which can occur in rollover motor vehicle accidents, or may represent atraumatic instability. In patients younger than 25 years, physeal separation is more common than true dislocation. Theoretically, these patients have increased remodeling potential. Reduction is recommended to prevent and/or manage the compression of mediastinal structures, which can lead to life-threatening injury. Open surgical stabilization is the preferred treatment for acute and chronic retrosternal injuries. A thoracic or trauma surgeon should be available during stabilization in the rare event of potentially life-threatening hemorrhage after reduction. Outcomes have been largely successful, with pain-free, unrestricted range of motion and return to activity. PMID:26116848

  3. Nanotherapy for posterior eye diseases.

    PubMed

    Kaur, Indu Pal; Kakkar, Shilpa

    2014-11-10

    It is assumed that more than 50% of the most enfeebling ocular diseases have their origin in the posterior segment. Furthermore, most of these diseases lead to partial or complete blindness, if left untreated. After cancer, blindness is the second most dreaded disease world over. However, treatment of posterior eye diseases is more challenging than the anterior segment ailments due to a series of anatomical barriers and physiological constraints confronted for delivery to this segment. In this regard, nanostructured drug delivery systems are proposed to defy ocular barriers, target retina, and act as permeation enhancers in addition to providing a controlled release. Since an important step towards developing effective treatment strategies is to understand the course or a route a drug molecule needs to follow to reach the target site, the first part of the present review discusses various pathways available for effective delivery to and clearance from the posterior eye. Promise held by nanocarrier systems, viz. liposomes, nanoparticles, and nanoemulsion, for effective delivery and selective targeting is also discussed with illustrative examples, tables, and flowcharts. However, the applicability of these nanocarrier systems as self-administration ocular drops is still an unrealized dream which is in itself a huge technological challenge. PMID:24862316

  4. On Probability Domains III

    NASA Astrophysics Data System (ADS)

    Frič, Roman; Papčo, Martin

    2015-12-01

    Domains of generalized probability have been introduced in order to provide a general construction of random events, observables and states. It is based on the notion of a cogenerator and the properties of product. We continue our previous study and show how some other quantum structures fit our categorical approach. We discuss how various epireflections implicitly used in the classical probability theory are related to the transition to fuzzy probability theory and describe the latter probability theory as a genuine categorical extension of the former. We show that the IF-probability can be studied via the fuzzy probability theory. We outline a "tensor modification" of the fuzzy probability theory.

  5. Neural representation of probabilities for Bayesian inference

    PubMed Central

    Rich, Dylan; Cazettes, Fanny; Wang, Yunyan; Peña, José Luis; Fischer, Brian J.

    2015-01-01

    Bayesian models are often successful in describing perception and behavior, but the neural representation of probabilities remains in question. There are several distinct proposals for the neural representation of probabilities, but they have not been directly compared in an example system. Here we consider three models: a non-uniform population code where the stimulus-driven activity and distribution of preferred stimuli in the population represent a likelihood function and a prior, respectively; the sampling hypothesis which proposes that the stimulus-driven activity over time represents a posterior probability and that the spontaneous activity represents a prior; and the class of models which propose that a population of neurons represents a posterior probability in a distributed code. It has been shown that the non-uniform population code model matches the representation of auditory space generated in the owl's external nucleus of the inferior colliculus (ICx). However, the alternative models have not been tested, nor have the three models been directly compared in any system. Here we tested the three models in the owl's ICx. We found that spontaneous firing rate and the average stimulus-driven response of these neurons were not consistent with predictions of the sampling hypothesis. We also found that neural activity in ICx under varying levels of sensory noise did not reflect a posterior probability. On the other hand, the responses of ICx neurons were consistent with the non-uniform population code model. We further show that Bayesian inference can be implemented in the non uniform population code model using one spike per neuron when the population is large and is thus able to support the rapid inference that is necessary for sound localization. PMID:25561333

  6. Markov chain Monte Carlo posterior sampling with the Hamiltonian method.

    SciTech Connect

    Hanson, Kenneth M.

    2001-01-01

    A major advantage of Bayesian data analysis is that provides a characterization of the uncertainty in the model parameters estimated from a given set of measurements in the form of a posterior probability distribution. When the analysis involves a complicated physical phenomenon, the posterior may not be available in analytic form, but only calculable by means of a simulation code. In such cases, the uncertainty in inferred model parameters requires characterization of a calculated functional. An appealing way to explore the posterior, and hence characterize the uncertainty, is to employ the Markov Chain Monte Carlo technique. The goal of MCMC is to generate a sequence random of parameter x samples from a target pdf (probability density function), {pi}(x). In Bayesian analysis, this sequence corresponds to a set of model realizations that follow the posterior distribution. There are two basic MCMC techniques. In Gibbs sampling, typically one parameter is drawn from the conditional pdf at a time, holding all others fixed. In the Metropolis algorithm, all the parameters can be varied at once. The parameter vector is perturbed from the current sequence point by adding a trial step drawn randomly from a symmetric pdf. The trial position is either accepted or rejected on the basis of the probability at the trial position relative to the current one. The Metropolis algorithm is often employed because of its simplicity. The aim of this work is to develop MCMC methods that are useful for large numbers of parameters, n, say hundreds or more. In this regime the Metropolis algorithm can be unsuitable, because its efficiency drops as 0.3/n. The efficiency is defined as the reciprocal of the number of steps in the sequence needed to effectively provide a statistically independent sample from {pi}.

  7. Probability and Relative Frequency

    NASA Astrophysics Data System (ADS)

    Drieschner, Michael

    2016-01-01

    The concept of probability seems to have been inexplicable since its invention in the seventeenth century. In its use in science, probability is closely related with relative frequency. So the task seems to be interpreting that relation. In this paper, we start with predicted relative frequency and show that its structure is the same as that of probability. I propose to call that the `prediction interpretation' of probability. The consequences of that definition are discussed. The "ladder"-structure of the probability calculus is analyzed. The expectation of the relative frequency is shown to be equal to the predicted relative frequency. Probability is shown to be the most general empirically testable prediction.

  8. Posterior ankyloglossia: a case report.

    PubMed

    Chu, Michael W; Bloom, David C

    2009-06-01

    Ankyloglossia, or tongue-tie, refers to an abnormally short lingual frenulum. Ankyloglossia is a recognized but poorly defined condition and has been reported to cause feeding difficulties, dysarthria, dyspnea, and social or mechanical problems. In infants, the most concerning symptoms are feeding difficulties and inability to breastfeed. While a recent trend toward breastfeeding has brought frenulectomy back into favor, the literature regarding treatment remains inconclusive. We report a case of posterior ankyloglossia with anterior mucosal hooding and a simple, safe, and effective way to treat it to improve breastfeeding. PMID:19303646

  9. FEMORAL INSERTION OF THE POSTERIOR CRUCIATE LIGAMENT: AN ANATOMICAL STUDY

    PubMed Central

    de Paula Leite Cury, Ricardo; Severino, Nilson Roberto; Camargo, Osmar Pedro Arbix; Aihara, Tatsuo; Neto, Leopoldo Viana Batista; Goarayeb, Dedley Nelson

    2015-01-01

    Objective: To identify objective parameters to guide correct location of the posterior cruciate ligament (PCL) in the femur. Methods: The PCLs of 20 human cadavers were resected. The following portions were measured: distance from the most distal portion of the PCL, close to the roof, to the most anterior edge of the cartilage (AB); distance from the most proximal portion of the PCL, close to the roof, to the most anterior cartilage (AC); distance between the two parts of the ligament close to the roof (BC); distance from the distal edge in its posterior portion, to the more posterior joint edge (DE); distance from the distal edge of the ligament in its posterior portion, to the intercondylar roof (DF); and finally, the format of the ligament insertion and area of coverage on the femoral condyle. Results: The PCL has the shape of a quarter ellipse, with an average area of 153.5mm2. The mean distances found were: AB of 2.1mm, AC of 10.7mm, BC of 8.6mm DE of 12.4mm and DF of 16.8mm. Conclusions: The edge close to the roof of the anterolateral bundle is closer to the joint cartilage (2.1mm) than the posteromedial bundle is, which is 12.4mm from the edge proximal to the cartilage. These references should assist in better and more accurate positioning of femoral tunnels in PCL reconstruction. PMID:27027059

  10. Bilateral posterior shoulder dislocation after electrical shock: A case report

    PubMed Central

    Ketenci, Ismail Emre; Duymus, Tahir Mutlu; Ulusoy, Ayhan; Yanik, Hakan Serhat; Mutlu, Serhat; Durakbasa, Mehmet Oguz

    2015-01-01

    Introduction Posterior dislocation of the shoulder is a rare and commonly missed injury. Unilateral dislocations occur mostly due to trauma. Bilateral posterior shoulder dislocations are even more rare and result mainly from epileptic seizures. Electrical injury is a rare cause of posterior shoulder dislocation. Injury mechanism in electrical injury is similar to epileptic seizures, where the shoulder is forced to internal rotation, flexion and adduction. Presentation of case This report presents a case of bilateral posterior shoulder dislocation after electrical shock. We were able to find a few individual case reports describing this condition. The case was acute and humeral head impression defects were minor. Our treatment in this case consisted of closed reduction under general anesthesia and applying of orthoses which kept the shoulders in abduction and external rotation. A rehabilitation program was begun after 3 weeks of immobilization. After 6 months of injury the patient has returned to work. 20 months postoperatively, at final follow-up, he was painless and capable of performing all of his daily activities. Discussion The amount of bilateral shoulder dislocations after electrical injury is not reported but is known to be very rare. The aim of this case presentation is to report an example for this rare entity, highlight the difficulties in diagnosis and review the treatment options. Conclusion Physical examination and radiographic evaluation are important for quick and accurate diagnosis. PMID:26904192

  11. Predicted probabilities' relationship to inclusion probabilities.

    PubMed

    Fang, Di; Chong, Jenny; Wilson, Jeffrey R

    2015-05-01

    It has been shown that under a general multiplicative intercept model for risk, case-control (retrospective) data can be analyzed by maximum likelihood as if they had arisen prospectively, up to an unknown multiplicative constant, which depends on the relative sampling fraction. (1) With suitable auxiliary information, retrospective data can also be used to estimate response probabilities. (2) In other words, predictive probabilities obtained without adjustments from retrospective data will likely be different from those obtained from prospective data. We highlighted this using binary data from Medicare to determine the probability of readmission into the hospital within 30 days of discharge, which is particularly timely because Medicare has begun penalizing hospitals for certain readmissions. (3). PMID:25790398

  12. Longevity of Posterior Composite Restorations

    PubMed Central

    Opdam, N.J.M.; van de Sande, F.H.; Bronkhorst, E.; Cenci, M.S.; Bottenberg, P.; Pallesen, U.; Gaengler, P.; Lindberg, A.; Huysmans, M.C.D.N.J.M.; van Dijken, J.W.

    2014-01-01

    The aim of this meta-analysis, based on individual participant data from several studies, was to investigate the influence of patient-, materials-, and tooth-related variables on the survival of posterior resin composite restorations. Following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, we conducted a search resulting in 12 longitudinal studies of direct posterior resin composite restorations with at least 5 years follow-up. Original datasets were still available, including placement/failure/censoring of restorations, restored surfaces, materials used, reasons for clinical failure, and caries-risk status. A database including all restorations was constructed, and a multivariate Cox regression method was used to analyze variables of interest [patient (age; gender; caries-risk status), jaw (upper; lower), number of restored surfaces, resin composite and adhesive materials, and use of glass-ionomer cement as base/liner (present or absent)]. The hazard ratios with respective 95% confidence intervals were determined, and annual failure rates were calculated for subgroups. Of all restorations, 2,816 (2,585 Class II and 231 Class I) were included in the analysis, of which 569 failed during the observation period. Main reasons for failure were caries and fracture. The regression analyses showed a significantly higher risk of failure for restorations in high-caries-risk individuals and those with a higher number of restored surfaces. PMID:25048250

  13. Searching with probabilities

    SciTech Connect

    Palay, A.J.

    1985-01-01

    This book examines how probability distributions can be used as a knowledge representation technique. It presents a mechanism that can be used to guide a selective search algorithm to solve a variety of tactical chess problems. Topics covered include probabilities and searching the B algorithm and chess probabilities - in practice, examples, results, and future work.

  14. Dependent Probability Spaces

    ERIC Educational Resources Information Center

    Edwards, William F.; Shiflett, Ray C.; Shultz, Harris

    2008-01-01

    The mathematical model used to describe independence between two events in probability has a non-intuitive consequence called dependent spaces. The paper begins with a very brief history of the development of probability, then defines dependent spaces, and reviews what is known about finite spaces with uniform probability. The study of finite…

  15. In All Probability, Probability is not All

    ERIC Educational Resources Information Center

    Helman, Danny

    2004-01-01

    The national lottery is often portrayed as a game of pure chance with no room for strategy. This misperception seems to stem from the application of probability instead of expectancy considerations, and can be utilized to introduce the statistical concept of expectation.

  16. On differentiating the probability of error in multipopular feature selection

    NASA Technical Reports Server (NTRS)

    Peters, B. C.

    1974-01-01

    A method of linear feature selection for n dimensional observation vectors which belong to one of m populations is presented. Each population has a known apriori probability and is described by a known multivariate normal density function. Specifically we consider the problem of finding a k x n matrix B of rank k (k n) for which the transformed probability of misclassification is minimized. Providing that the transformed a posterior probabilities are distinct theoretical results are obtained which, for the case k = l, give rise to a numerically tractable formula for the derivative of the probability of misclassification. It is shown that for the two population problem this condition is also necessary. The dependence of the minimum probability of error on the a priori probabilities is investigated. The minimum probability of error satisfies a uniform Lipschitz condition with respect to the a priori probabilities.

  17. Flood hazard probability mapping method

    NASA Astrophysics Data System (ADS)

    Kalantari, Zahra; Lyon, Steve; Folkeson, Lennart

    2015-04-01

    In Sweden, spatially explicit approaches have been applied in various disciplines such as landslide modelling based on soil type data and flood risk modelling for large rivers. Regarding flood mapping, most previous studies have focused on complex hydrological modelling on a small scale whereas just a few studies have used a robust GIS-based approach integrating most physical catchment descriptor (PCD) aspects on a larger scale. The aim of the present study was to develop methodology for predicting the spatial probability of flooding on a general large scale. Factors such as topography, land use, soil data and other PCDs were analysed in terms of their relative importance for flood generation. The specific objective was to test the methodology using statistical methods to identify factors having a significant role on controlling flooding. A second objective was to generate an index quantifying flood probability value for each cell, based on different weighted factors, in order to provide a more accurate analysis of potential high flood hazards than can be obtained using just a single variable. The ability of indicator covariance to capture flooding probability was determined for different watersheds in central Sweden. Using data from this initial investigation, a method to subtract spatial data for multiple catchments and to produce soft data for statistical analysis was developed. It allowed flood probability to be predicted from spatially sparse data without compromising the significant hydrological features on the landscape. By using PCD data, realistic representations of high probability flood regions was made, despite the magnitude of rain events. This in turn allowed objective quantification of the probability of floods at the field scale for future model development and watershed management.

  18. Decoding Trajectories from Posterior Parietal Cortex Ensembles

    PubMed Central

    Mulliken, Grant H.; Musallam, Sam; Andersen, Richard A.

    2009-01-01

    High-level cognitive signals in the posterior parietal cortex (PPC) have previously been used to decode the intended endpoint of a reach, providing the first evidence that PPC can be used for direct control of a neural prosthesis (Musallam et al., 2004). Here we expand on this work by showing that PPC neural activity can be harnessed to estimate not only the endpoint but also to continuously control the trajectory of an end effector. Specifically, we trained two monkeys to use a joystick to guide a cursor on a computer screen to peripheral target locations while maintaining central ocular fixation. We found that we could accurately reconstruct the trajectory of the cursor using a relatively small ensemble of simultaneously recorded PPC neurons. Using a goal-based Kalman filter that incorporates target information into the state-space, we showed that the decoded estimate of cursor position could be significantly improved. Finally, we tested whether we could decode trajectories during closed-loop brain control sessions, in which the real-time position of the cursor was determined solely by a monkey’s neural activity in PPC. The monkey learned to perform brain control trajectories at 80% success rate(for 8 targets) after just 4–5 sessions. This improvement in behavioral performance was accompanied by a corresponding enhancement in neural tuning properties (i.e., increased tuning depth and coverage of encoding parameter space) as well as an increase in off-line decoding performance of the PPC ensemble. PMID:19036985

  19. Downregulation of the posterior medial frontal cortex prevents social conformity.

    PubMed

    Klucharev, Vasily; Munneke, Moniek A M; Smidts, Ale; Fernández, Guillén

    2011-08-17

    We often change our behavior to conform to real or imagined group pressure. Social influence on our behavior has been extensively studied in social psychology, but its neural mechanisms have remained largely unknown. Here we demonstrate that the transient downregulation of the posterior medial frontal cortex by theta-burst transcranial magnetic stimulation reduces conformity, as indicated by reduced conformal adjustments in line with group opinion. Both the extent and probability of conformal behavioral adjustments decreased significantly relative to a sham and a control stimulation over another brain area. The posterior part of the medial frontal cortex has previously been implicated in behavioral and attitudinal adjustments. Here, we provide the first interventional evidence of its critical role in social influence on human behavior. PMID:21849554

  20. Reconstruction of Posterior Trunk Defects

    PubMed Central

    Hallock, Geoffrey G.

    2011-01-01

    The posterior trunk roughly encompasses the upper back from the shoulders to the lumbar area above the iliac crests. Long-term outcomes in the treatment of defects of the spine and bony thorax have been proved superior if flaps were used. Many local muscle and fasciocutaneous flaps are available alternatives. A guideline, patterned according to arbitrary anatomic territories of the back, is suggested as a starting point for the selection of appropriate primary and secondary flap options. Depending on flap availability, the latissimus dorsi and trapezius muscles are the workhorse flaps for the upper back, whereas perforator flaps have become a useful alternative for the lumbar region in lieu of free flaps. PMID:22294946

  1. Posterior mediastinal hyperfunctioning insular thyroid carcinoma.

    PubMed

    Bellantone, Rocco; Lombardi, Celestino Pio; Bossola, Maurizio; Fadda, Guido; Salvatori, Massimo; Princi, Pietro

    2005-01-01

    A case is presented of a posterior mediastinal mass arising in a 57-year-old woman with severe compressive cervical symptoms and hyperthyroidism. Computed tomography showed intrathoracic thyroid tissue that displaced the trachea towards the front and the right and invaded the posterior mediastinum. Pathological examination showed features of a poorly differentiated (insular) thyroid carcinoma. To the best of our knowledge, this is the first reported case of a posterior mediastinal insular thyroid carcinoma with thyroid hyperfunction. PMID:16277105

  2. Teachers' Understandings of Probability

    ERIC Educational Resources Information Center

    Liu, Yan; Thompson, Patrick

    2007-01-01

    Probability is an important idea with a remarkably wide range of applications. However, psychological and instructional studies conducted in the last two decades have consistently documented poor understanding of probability among different populations across different settings. The purpose of this study is to develop a theoretical framework for…

  3. Pseudoaneurysm of the Posterior Tibial Artery After Posterior Tibial Tendon Transfer.

    PubMed

    Elabdi, Monsef; Roukhsi, Redouane; Tijani, Youssef; Chtata, Hassan; Jaafar, Abdeloihab

    2016-01-01

    Pseudoaneurysm of the posterior tibial artery is an uncommon condition that, left untreated, can lead to hemorrhage, thrombosis, or emboli. We present the case of a 54-year-old male who developed pseudoaneurysm of the posterior tibial artery 4 months after undergoing tibialis posterior tendon transfer for management of peroneal nerve palsy, which had developed as a complication of hip arthroplasty. PMID:26972754

  4. Consistently inconsistent, the posterior vaginal wall.

    PubMed

    Hale, Douglass S; Fenner, Dee

    2016-03-01

    Posterior vaginal wall prolapse is one of the most common prolapses encountered by gynecological surgeons. What appears to be a straightforward condition to diagnose and treat surgically for physicians has proven to be frustratingly unpredictable with regard to symptom relief for patients. Functional disorders such as dyssynergic defecation and constipation are often attributed to posterior vaginal wall prolapse. Little scientific evidence supports this assumption, emphasizing that structure and function are not synonymous when treating posterior vaginal wall prolapse. Rectoceles, enteroceles, sigmoidoceles, peritoneoceles, rectal and intraanal intussusception, rectal prolapse, and descending perineal syndrome are all conditions that have an impact on the posterior vaginal wall. All too often these different anatomic conditions are treated with the same surgical approach, addressing a posterior vaginal wall bulge with a traditional posterior colporrhaphy. Studies that examine the correlation between stage of posterior wall prolapse and patient symptoms have failed to reliably do so. Surgical outcomes measured by prolapse staging appear successful, yet patient expectations are often not met. As increasing attention is being placed on patient satisfaction outcomes concerning surgical treatments, this fact will need to be addressed. Surgeons will have to clearly communicate what can and what cannot be expected with surgical repair of posterior vaginal wall prolapse. PMID:26348375

  5. Neurolinguistic Aspects of Finnish Posterior Aphasia.

    ERIC Educational Resources Information Center

    Niemi, Jussi; Koivuselka-Sallinen, Paivi

    Examination of the lexical errors (phonological paraphasias and neologisms) of two posterior aphasic patients who are speakers of Finnish, a highly synthetic language, revealed that the lexical difficulties generally typical of posterior aphasics were found in these patients as well. The typical lexical difficulties clustered around open class…

  6. Posterior Cervical Foraminotomy: Indications, Technique, and Outcomes.

    PubMed

    Dodwad, Shah-Jahan M; Dodwad, Shah-Nawaz M; Prasarn, Mark L; Savage, Jason W; Patel, Alpesh A; Hsu, Wellington K

    2016-06-01

    Cervical radiculopathy presents with upper extremity pain, decreased sensation, and decreased strength caused by irritation of specific nerve root(s). After failure of conservative management, surgical options include anterior cervical decompression and fusion, disk arthroplasty, and posterior cervical foraminotomy. In this review, we discuss indications, techniques, and outcomes of posterior cervical laminoforaminotomy. PMID:27187617

  7. Grading More Accurately

    ERIC Educational Resources Information Center

    Rom, Mark Carl

    2011-01-01

    Grades matter. College grading systems, however, are often ad hoc and prone to mistakes. This essay focuses on one factor that contributes to high-quality grading systems: grading accuracy (or "efficiency"). I proceed in several steps. First, I discuss the elements of "efficient" (i.e., accurate) grading. Next, I present analytical results…

  8. Posterior talus osteochondroma a rare location, treated by posterior ankle arthroscopy.

    PubMed

    Kulkarni, Umesh; Kulkarni, Ameya

    2015-09-01

    The common cause of posterior ankle impingement syndrome is impingement of the Os trigonum or the posterior talar process. We report a case of a 46-year-old lady having osteochondroma of the posterior talar process, a rare occurrence at this site. This patient was treated with posterior ankle arthroscopic excision through the 2-portal posterior ankle arthroscopy technique in the prone position. 6 months post-operatively, her ankle pain disappeared and ankle range of movement improved significantly and there is no recurrence of the tumour. PMID:26235872

  9. Guide star probabilities

    NASA Technical Reports Server (NTRS)

    Soneira, R. M.; Bahcall, J. N.

    1981-01-01

    Probabilities are calculated for acquiring suitable guide stars (GS) with the fine guidance system (FGS) of the space telescope. A number of the considerations and techniques described are also relevant for other space astronomy missions. The constraints of the FGS are reviewed. The available data on bright star densities are summarized and a previous error in the literature is corrected. Separate analytic and Monte Carlo calculations of the probabilities are described. A simulation of space telescope pointing is carried out using the Weistrop north galactic pole catalog of bright stars. Sufficient information is presented so that the probabilities of acquisition can be estimated as a function of position in the sky. The probability of acquiring suitable guide stars is greatly increased if the FGS can allow an appreciable difference between the (bright) primary GS limiting magnitude and the (fainter) secondary GS limiting magnitude.

  10. Probability with Roulette

    ERIC Educational Resources Information Center

    Marshall, Jennings B.

    2007-01-01

    This article describes how roulette can be used to teach basic concepts of probability. Various bets are used to illustrate the computation of expected value. A betting system shows variations in patterns that often appear in random events.

  11. Adaptive approximation of higher order posterior statistics

    SciTech Connect

    Lee, Wonjung

    2014-02-01

    Filtering is an approach for incorporating observed data into time-evolving systems. Instead of a family of Dirac delta masses that is widely used in Monte Carlo methods, we here use the Wiener chaos expansion for the parametrization of the conditioned probability distribution to solve the nonlinear filtering problem. The Wiener chaos expansion is not the best method for uncertainty propagation without observations. Nevertheless, the projection of the system variables in a fixed polynomial basis spanning the probability space might be a competitive representation in the presence of relatively frequent observations because the Wiener chaos approach not only leads to an accurate and efficient prediction for short time uncertainty quantification, but it also allows to apply several data assimilation methods that can be used to yield a better approximate filtering solution. The aim of the present paper is to investigate this hypothesis. We answer in the affirmative for the (stochastic) Lorenz-63 system based on numerical simulations in which the uncertainty quantification method and the data assimilation method are adaptively selected by whether the dynamics is driven by Brownian motion and the near-Gaussianity of the measure to be updated, respectively.

  12. Estimating the Probability of Negative Events

    ERIC Educational Resources Information Center

    Harris, Adam J. L.; Corner, Adam; Hahn, Ulrike

    2009-01-01

    How well we are attuned to the statistics of our environment is a fundamental question in understanding human behaviour. It seems particularly important to be able to provide accurate assessments of the probability with which negative events occur so as to guide rational choice of preventative actions. One question that arises here is whether or…

  13. Estimating the Probability of Negative Events

    ERIC Educational Resources Information Center

    Harris, Adam J. L.; Corner, Adam; Hahn, Ulrike

    2009-01-01

    How well we are attuned to the statistics of our environment is a fundamental question in understanding human behaviour. It seems particularly important to be able to provide accurate assessments of the probability with which negative events occur so as to guide rational choice of preventative actions. One question that arises here is whether or

  14. Accurate monotone cubic interpolation

    NASA Technical Reports Server (NTRS)

    Huynh, Hung T.

    1991-01-01

    Monotone piecewise cubic interpolants are simple and effective. They are generally third-order accurate, except near strict local extrema where accuracy degenerates to second-order due to the monotonicity constraint. Algorithms for piecewise cubic interpolants, which preserve monotonicity as well as uniform third and fourth-order accuracy are presented. The gain of accuracy is obtained by relaxing the monotonicity constraint in a geometric framework in which the median function plays a crucial role.

  15. Accurate Finite Difference Algorithms

    NASA Technical Reports Server (NTRS)

    Goodrich, John W.

    1996-01-01

    Two families of finite difference algorithms for computational aeroacoustics are presented and compared. All of the algorithms are single step explicit methods, they have the same order of accuracy in both space and time, with examples up to eleventh order, and they have multidimensional extensions. One of the algorithm families has spectral like high resolution. Propagation with high order and high resolution algorithms can produce accurate results after O(10(exp 6)) periods of propagation with eight grid points per wavelength.

  16. Experimental Probability in Elementary School

    ERIC Educational Resources Information Center

    Andrew, Lane

    2009-01-01

    Concepts in probability can be more readily understood if students are first exposed to probability via experiment. Performing probability experiments encourages students to develop understandings of probability grounded in real events, as opposed to merely computing answers based on formulae.

  17. Posterior Hip Pain in an Athletic Population

    PubMed Central

    Frank, Rachel M.; Slabaugh, Mark A.; Grumet, Robert C.; Virkus, Walter W.; Bush-Joseph, Charles A.; Nho, Shane J.

    2010-01-01

    Context: Posterior hip pain is a relatively uncommon but increasingly recognized complaint in the orthopaedic community. Patient complaints and presentations are often vague or nonspecific, making diagnosis and subsequent treatment decisions difficult. The purposes of this article are to review the anatomy and pathophysiology related to posterior hip pain in the athletic patient population. Evidence Acquisition: Data were collected through a thorough review of the literature via a MEDLINE search of all relevant articles between 1980 and 2010. Results: Many patients who complain of posterior hip pain actually have pain referred from another part of the body—notably, the lumbar spine or sacroiliac joint. Treatment options for posterior hip pain are typically nonoperative; however, surgery is warranted in some cases. Conclusions: Recent advancements in the understanding of hip anatomy, pathophysiology, and treatment options have enabled physicians to better diagnosis athletic hip injuries and select patients for appropriate treatment. PMID:23015944

  18. Posterior cruciate ligament (PCL) injury - aftercare

    MedlinePlus

    ... posterior cruciate ligament (PCL) is located inside your knee joint and connects the bones of your upper and ... such as a knee dislocation , you will need knee surgery to repair the joint. For milder injuries, you may not need surgery. ...

  19. Gaussianization for fast and accurate inference from cosmological data

    NASA Astrophysics Data System (ADS)

    Schuhmann, Robert L.; Joachimi, Benjamin; Peiris, Hiranya V.

    2016-06-01

    We present a method to transform multivariate unimodal non-Gaussian posterior probability densities into approximately Gaussian ones via non-linear mappings, such as Box-Cox transformations and generalizations thereof. This permits an analytical reconstruction of the posterior from a point sample, like a Markov chain, and simplifies the subsequent joint analysis with other experiments. This way, a multivariate posterior density can be reported efficiently, by compressing the information contained in Markov Chain Monte Carlo samples. Further, the model evidence integral (i.e. the marginal likelihood) can be computed analytically. This method is analogous to the search for normal parameters in the cosmic microwave background, but is more general. The search for the optimally Gaussianizing transformation is performed computationally through a maximum-likelihood formalism; its quality can be judged by how well the credible regions of the posterior are reproduced. We demonstrate that our method outperforms kernel density estimates in this objective. Further, we select marginal posterior samples from Planck data with several distinct strongly non-Gaussian features, and verify the reproduction of the marginal contours. To demonstrate evidence computation, we Gaussianize the joint distribution of data from weak lensing and baryon acoustic oscillations, for different cosmological models, and find a preference for flat Λcold dark matter. Comparing to values computed with the Savage-Dickey density ratio, and Population Monte Carlo, we find good agreement of our method within the spread of the other two.

  20. Gaussianisation for fast and accurate inference from cosmological data

    NASA Astrophysics Data System (ADS)

    Schuhmann, Robert L.; Joachimi, Benjamin; Peiris, Hiranya V.

    2016-04-01

    We present a method to transform multivariate unimodal non-Gaussian posterior probability densities into approximately Gaussian ones via non-linear mappings, such as Box-Cox transformations and generalisations thereof. This permits an analytical reconstruction of the posterior from a point sample, like a Markov chain, and simplifies the subsequent joint analysis with other experiments. This way, a multivariate posterior density can be reported efficiently, by compressing the information contained in MCMC samples. Further, the model evidence integral (i.e. the marginal likelihood) can be computed analytically. This method is analogous to the search for normal parameters in the cosmic microwave background, but is more general. The search for the optimally Gaussianising transformation is performed computationally through a maximum-likelihood formalism; its quality can be judged by how well the credible regions of the posterior are reproduced. We demonstrate that our method outperforms kernel density estimates in this objective. Further, we select marginal posterior samples from Planck data with several distinct strongly non-Gaussian features, and verify the reproduction of the marginal contours. To demonstrate evidence computation, we Gaussianise the joint distribution of data from weak lensing and baryon acoustic oscillations (BAO), for different cosmological models, and find a preference for flat ΛCDM. Comparing to values computed with the Savage-Dickey density ratio, and Population Monte Carlo, we find good agreement of our method within the spread of the other two.

  1. Estimating tail probabilities

    SciTech Connect

    Carr, D.B.; Tolley, H.D.

    1982-12-01

    This paper investigates procedures for univariate nonparametric estimation of tail probabilities. Extrapolated values for tail probabilities beyond the data are also obtained based on the shape of the density in the tail. Several estimators which use exponential weighting are described. These are compared in a Monte Carlo study to nonweighted estimators, to the empirical cdf, to an integrated kernel, to a Fourier series estimate, to a penalized likelihood estimate and a maximum likelihood estimate. Selected weighted estimators are shown to compare favorably to many of these standard estimators for the sampling distributions investigated.

  2. An unusual cause of posterior mediastinal cyst.

    PubMed

    Dhooria, Sahajal; Muthu, Valliappan; Agarwal, Ritesh

    2015-01-01

    Cystic lesions of the mediastinum may be congenital or acquired. The differential diagnosis depends on their location in the mediastinum. Cysts in the posterior mediastinum are generally developmental cysts and are neurogenic or of foregut origin. We report the case of a 14-year-old boy, who presented with dry cough and progressively increasing breathlessness, and was found to have a cystic lesion in the posterior mediastinum. Fine needle aspiration from the cyst helped make a diagnosis of tuberculosis. PMID:26664169

  3. Posterior Shoulder Instability in Overhead Athletes.

    PubMed

    Chang, Edward S; Greco, Nicholas J; McClincy, Michael P; Bradley, James P

    2016-01-01

    Posterior shoulder instability in overhead athletes presents a unique and difficult challenge. Often, this group has an inherent capsular laxity and/or humeral retroversion to accommodate the range of motion necessary to throw. This adaptation makes the diagnosis of posterior capsulolabral pathology challenging, as the examiner must differentiate between adaptive capsular laxity and pathologic instability. Further complicating matters, the intraoperative surgeon must find the delicate balance of achieving stability while still allowing the necessary range of motion. PMID:26614932

  4. Advances in posterior cruciate ligament reconstruction.

    PubMed

    Levy, Bruce A; Fanelli, Gregory C; Miller, Mark D; Stuart, Michael J

    2015-01-01

    Current advances in posterior cruciate ligament reconstruction have led to excellent clinical and functional outcomes. It is helpful to review anatomy, cadaver sectioning studies, biomechanical studies, clinical outcome data, and novel surgical techniques for posterior cruciate ligament reconstruction, including all-inside reconstructions. Surgeons also should be aware of current controversies regarding transtibial versus inlay, autograft versus allograft, and single-bundle versus double-bundle reconstructions. PMID:25745937

  5. Concomitant anterior and posterior infantile perianal protrusions.

    PubMed

    Leung, Alexander K C

    2010-02-01

    Infantile perianal protrusion is characterized by asymptomatic pyramidal protrusion with a rose-red or purplish red surface along the midline, usually anterior to the anus. The protrusion is usually solitary. Two girls are reported with concomitant anterior and posterior infantile perianal pyramidal protrusions and a history of constipation. The occurrence of concomitant anterior and posterior infantile perianal pyramidal protrusions has not been reported previously. PMID:20191927

  6. Univariate Probability Distributions

    ERIC Educational Resources Information Center

    Leemis, Lawrence M.; Luckett, Daniel J.; Powell, Austin G.; Vermeer, Peter E.

    2012-01-01

    We describe a web-based interactive graphic that can be used as a resource in introductory classes in mathematical statistics. This interactive graphic presents 76 common univariate distributions and gives details on (a) various features of the distribution such as the functional form of the probability density function and cumulative distribution…

  7. A Unifying Probability Example.

    ERIC Educational Resources Information Center

    Maruszewski, Richard F., Jr.

    2002-01-01

    Presents an example from probability and statistics that ties together several topics including the mean and variance of a discrete random variable, the binomial distribution and its particular mean and variance, the sum of independent random variables, the mean and variance of the sum, and the central limit theorem. Uses Excel to illustrate these…

  8. Approximating Integrals Using Probability

    ERIC Educational Resources Information Center

    Maruszewski, Richard F., Jr.; Caudle, Kyle A.

    2005-01-01

    As part of a discussion on Monte Carlo methods, which outlines how to use probability expectations to approximate the value of a definite integral. The purpose of this paper is to elaborate on this technique and then to show several examples using visual basic as a programming tool. It is an interesting method because it combines two branches of…

  9. Influence of monkey dorsolateral prefrontal and posterior parietal activity on behavioral choice during attention tasks

    PubMed Central

    Katsuki, Fumi; Saito, Mizuki; Constantinidis, Christos

    2014-01-01

    The dorsolateral prefrontal and the posterior parietal cortex have both been implicated in the guidance of visual attention. Traditionally, posterior parietal cortex has been thought to guide visual bottom-up attention, whereas prefrontal cortex to bias attention through top-down information. More recent studies suggest a parallel time course of activation of the two areas in bottom-up attention tasks, suggesting a common involvement, though these results do not necessarily imply identical roles, either. To address the specific roles of the two areas, we examined the influence of neuronal activity recorded from the prefrontal and parietal cortex of monkeys as they performed attention tasks based on choice probability and correlation between reaction time and neuronal activity. The results revealed that posterior parietal but not dorsolateral prefrontal activity correlated with behavioral choice during the fixation period, prior to the appearance of the stimulus, resembling a bias factor. This preferential influence of posterior parietal activity on behavior was transient, so that dorsolateral prefrontal activity predicted choice after the appearance of the stimulus. Additionally, reaction time was better predicted by posterior parietal activity. These findings confirm an involvement of both dorsolateral prefrontal and posterior parietal cortex in the bottom-up guidance of visual attention but indicate different roles of the two areas in the guidance of attention and a dynamic time course of their effects, influencing behavior at different stages of the task. PMID:24964224

  10. Arbitrarily accurate narrowband composite pulse sequences

    SciTech Connect

    Vitanov, Nikolay V.

    2011-12-15

    Narrowband composite pulse sequences containing an arbitrary number N of identical pulses are presented. The composite phases are given by a very simple analytic formula and the transition probability is merely sin{sup 2N}(A/2), where A is the pulse area. These narrowband sequences can be made accurate to any order with respect to variations in A for sufficiently many constituent pulses, i.e., excitation can be suppressed below any desired value for any pulse area but {pi}.

  11. Highly accurate nephelometric titrimetry.

    PubMed

    Zhan, Xiancheng; Li, Chengrong; Li, Zhiyi; Yang, Xiucen; Zhong, Shuguang; Yi, Tao

    2004-02-01

    A method that accurately indicates the end-point of precipitation reactions by the measurement of the relative intensity of the scattered light in the titrate is presented. A new nephelometric titrator with an internal nephelometric sensor has been devised. The work of the titrator including the sensor and change in the turbidity of the titrate and intensity of the scattered light are described. The accuracy of the nephelometric titrimetry is discussed theoretically. The titration of NaCl with AgNO(3) serves as a model. A relative error as well as deviation is within 0.2% under the experimental conditions. The applicability of the titrimetry in pharmaceutical analyses, for example, phenytoin sodium and procaine hydrochloride, is generally illustrated. PMID:14705200

  12. Accurate Inclusion Mass Screening

    PubMed Central

    Jaffe, Jacob D.; Keshishian, Hasmik; Chang, Betty; Addona, Theresa A.; Gillette, Michael A.; Carr, Steven A.

    2008-01-01

    Verification of candidate biomarker proteins in blood is typically done using multiple reaction monitoring (MRM) of peptides by LC-MS/MS on triple quadrupole MS systems. MRM assay development for each protein requires significant time and cost, much of which is likely to be of little value if the candidate biomarker is below the detection limit in blood or a false positive in the original discovery data. Here we present a new technology, accurate inclusion mass screening (AIMS), designed to provide a bridge from unbiased discovery to MS-based targeted assay development. Masses on the software inclusion list are monitored in each scan on the Orbitrap MS system, and MS/MS spectra for sequence confirmation are acquired only when a peptide from the list is detected with both the correct accurate mass and charge state. The AIMS experiment confirms that a given peptide (and thus the protein from which it is derived) is present in the plasma. Throughput of the method is sufficient to qualify up to a hundred proteins/week. The sensitivity of AIMS is similar to MRM on a triple quadrupole MS system using optimized sample preparation methods (low tens of ng/ml in plasma), and MS/MS data from the AIMS experiments on the Orbitrap can be directly used to configure MRM assays. The method was shown to be at least 4-fold more efficient at detecting peptides of interest than undirected LC-MS/MS experiments using the same instrumentation, and relative quantitation information can be obtained by AIMS in case versus control experiments. Detection by AIMS ensures that a quantitative MRM-based assay can be configured for that protein. The method has the potential to qualify large number of biomarker candidates based on their detection in plasma prior to committing to the time- and resource-intensive steps of establishing a quantitative assay. PMID:18534968

  13. Accurate quantum chemical calculations

    NASA Technical Reports Server (NTRS)

    Bauschlicher, Charles W., Jr.; Langhoff, Stephen R.; Taylor, Peter R.

    1989-01-01

    An important goal of quantum chemical calculations is to provide an understanding of chemical bonding and molecular electronic structure. A second goal, the prediction of energy differences to chemical accuracy, has been much harder to attain. First, the computational resources required to achieve such accuracy are very large, and second, it is not straightforward to demonstrate that an apparently accurate result, in terms of agreement with experiment, does not result from a cancellation of errors. Recent advances in electronic structure methodology, coupled with the power of vector supercomputers, have made it possible to solve a number of electronic structure problems exactly using the full configuration interaction (FCI) method within a subspace of the complete Hilbert space. These exact results can be used to benchmark approximate techniques that are applicable to a wider range of chemical and physical problems. The methodology of many-electron quantum chemistry is reviewed. Methods are considered in detail for performing FCI calculations. The application of FCI methods to several three-electron problems in molecular physics are discussed. A number of benchmark applications of FCI wave functions are described. Atomic basis sets and the development of improved methods for handling very large basis sets are discussed: these are then applied to a number of chemical and spectroscopic problems; to transition metals; and to problems involving potential energy surfaces. Although the experiences described give considerable grounds for optimism about the general ability to perform accurate calculations, there are several problems that have proved less tractable, at least with current computer resources, and these and possible solutions are discussed.

  14. Target detection and recognition using Markov modeling and probability updating

    NASA Astrophysics Data System (ADS)

    Kelly, Patrick A.; Derin, Haluk; Zhao, Renjian

    2000-04-01

    While extract methods (e.g., jump-diffusion algorithms) for performing maximum a posteriori (MAP) target detection and recognition can be very complex and computationally expensive, it is often not clear how to develop effective and less complex suboptimal methods. Also, MAP algorithms typically generate hard decisions, but for fusion applications it would often be more desirable to have probabilities or confidence levels for a range of alternatives. In this paper, we consider the application of a framework called probability propagation in Bayesian networks. This framework organizes computations for iterated approximations to posterior probabilities, and has been used recently by communications researchers to derive very effective iterative decoding algorithms. In this paper, we develop a Bayesian network model for the problem of target detection and recognition, and use it in conjunction with Markov models for target regions to derive a probability propagation algorithm for estimating target shape and label probabilities.

  15. Waste Package Misload Probability

    SciTech Connect

    J.K. Knudsen

    2001-11-20

    The objective of this calculation is to calculate the probability of occurrence for fuel assembly (FA) misloads (i.e., Fa placed in the wrong location) and FA damage during FA movements. The scope of this calculation is provided by the information obtained from the Framatome ANP 2001a report. The first step in this calculation is to categorize each fuel-handling events that occurred at nuclear power plants. The different categories are based on FAs being damaged or misloaded. The next step is to determine the total number of FAs involved in the event. Using the information, a probability of occurrence will be calculated for FA misload and FA damage events. This calculation is an expansion of preliminary work performed by Framatome ANP 2001a.

  16. Peripapillary and Posterior Scleral Mechanics, Part I – Development of an Anisotropic Hyperelastic Constitutive Model

    PubMed Central

    Downs, J. Crawford; Burgoyne, Claude F.; Suh, J-K. Francis

    2009-01-01

    Background The sclera is the white outer shell and principal load-bearing tissue of the eye as it sustains the intraocular pressure. We have hypothesized that the mechanical properties of the posterior sclera play a significant role in, and are altered by the development of glaucoma – an ocular disease manifested by structural damage to the optic nerve head. Method of Approach An anisotropic hyperelastic constitutive model is presented to simulate the mechanical behavior of the posterior sclera under acute elevations of intraocular pressure. The constitutive model is derived from fiber-reinforced composite theory, and incorporates stretch-induced stiffening of the reinforcing collagen fibers. Collagen fiber alignment was assumed to be multi-directional at local material points, confined within the plane tangent to the scleral surface, and described by the semi-circular von-Mises distribution. The introduction of a model parameter, namely the fiber concentration factor, was used to control collagen fiber alignment along a preferred fiber orientation. To investigate the effects of scleral collagen fiber alignment on the overall behaviors of the posterior sclera and optic nerve head, finite element simulations of an idealized eye were performed. The four output quantities analyzed were the scleral canal expansion, the scleral canal twist, the posterior scleral canal deformation and the posterior laminar deformation. Results A circumferential fiber organization in the sclera restrained scleral canal expansion but created posterior laminar deformation, whereas the opposite was observed with a meridional fiber organization. Additionally, the fiber concentration factor acted as an amplifying parameter on the considered outputs. Conclusions The present model simulation suggests that the posterior sclera has a large impact on the overall behavior of the optic nerve head. It is therefore primordial to provide accurate mechanical properties for this tissue. In a companion paper [1], we present a method to measure the 3-D deformations of monkey posterior sclera and extract mechanical properties based on the proposed constitutive model with an inverse finite element method. PMID:19388781

  17. Ossification of the Posterior Longitudinal Ligament: Imaging Findings in the Era of Cross-Sectional Imaging.

    PubMed

    Sartip, Kamyar A; Dong, Tuo; Ndukwe, Moses; East, James E; Graves, Joseph A; Davis, Bonnie; Midyett, F Allan; Duerinckx, Andre

    2015-01-01

    Imaging appearance and classification systems of ossification of the posterior longitudinal ligament (OPLL) on computed tomography and magnetic resonance imaging will be reviewed. Computed tomography evaluation most accurately demonstrates OPLL length and thickness, whereas magnetic resonance imaging has the advantage of demonstrating abnormal signal in the cord. Neurologic symptoms are most common in the cervical spine and are related to the degree of spinal stenosis and presence of cord edema. Surgical treatment usually involves cases of cervical OPLL and includes anterior or posterior decompression. PMID:26418541

  18. Comparison of the Combined Anterior-Posterior Approach versus Posterior-Only Approach in Scoliosis Treatment

    PubMed Central

    Pourfeizi, Hossein Hojjat; Sales, Jafar Ganjpour; Borran, Ghanbar; Alavi, Sahar

    2014-01-01

    Study Design This is descriptive analytical study. Purpose The present study aims at comparing treatment results found between the two groups comprising of patients who underwent posterior spinal fusion using thoracic pedicle screws and the ones who underwent combined anterior-posterior method, respectively. Overview of Literature There was controversy about surgical techniques including anterior, posterior, or a combined anterior-posterior approaches are applied to treat non-congenital scoliosis with surgical indications. Methods Medical records of 50 patients suffering from thoracic non-congenital scoliosis with curves exceeding 70° were reviewed. In this study, 25 patients who underwent posterior spinal fusion using thoracic pedicle screws were compared with 25 patients who underwent combined anterior-posterior method. Results Patients treated through posterior-only and combined approaches were respectively hospitalized for 11.84±5.18 and 26.5±5.2 days (p=0.001). There was a significant difference between these two groups considering intensive care unit admission duration (p=0.001), correction in sagittal view of X-ray (p=0.01), and number of days the patients underwent traction (0.001). Finally, coronal view was corrected without any significant difference (p=0.2). Conclusions According to our findings, it is hypothesized that posterior-only method is associated with some significant advantages and is an advisable method in patients with severe scoliosis over than 70°. PMID:24596599

  19. Interpreting Posterior Relative Risk Estimates in Disease-Mapping Studies

    PubMed Central

    Richardson, Sylvia; Thomson, Andrew; Best, Nicky; Elliott, Paul

    2004-01-01

    There is currently much interest in conducting spatial analyses of health outcomes at the small-area scale. This requires sophisticated statistical techniques, usually involving Bayesian models, to smooth the underlying risk estimates because the data are typically sparse. However, questions have been raised about the performance of these models for recovering the “true” risk surface, about the influence of the prior structure specified, and about the amount of smoothing of the risks that is actually performed. We describe a comprehensive simulation study designed to address these questions. Our results show that Bayesian disease-mapping models are essentially conservative, with high specificity even in situations with very sparse data but low sensitivity if the raised-risk areas have only a moderate (< 2-fold) excess or are not based on substantial expected counts (> 50 per area). Semiparametric spatial mixture models typically produce less smoothing than their conditional autoregressive counterpart when there is sufficient information in the data (moderate-size expected count and/or high true excess risk). Sensitivity may be improved by exploiting the whole posterior distribution to try to detect true raised-risk areas rather than just reporting and mapping the mean posterior relative risk. For the widely used conditional autoregressive model, we show that a decision rule based on computing the probability that the relative risk is above 1 with a cutoff between 70 and 80% gives a specific rule with reasonable sensitivity for a range of scenarios having moderate expected counts (~ 20) and excess risks (~1.5- to 2-fold). Larger (3-fold) excess risks are detected almost certainly using this rule, even when based on small expected counts, although the mean of the posterior distribution is typically smoothed to about half the true value. PMID:15198922

  20. International Comparative Evaluation of Knee Replacement with Fixed or Mobile-Bearing Posterior-Stabilized Prostheses

    PubMed Central

    Graves, Stephen; Sedrakyan, Art; Baste, Valborg; Gioe, Terence J.; Namba, Robert; Cruz, Olga Martínez; Stea, Susanna; Paxton, Elizabeth; Banerjee, Samprit; Isaacs, Abby J.; Robertsson, Otto

    2014-01-01

    Background: Posterior-stabilized total knee prostheses were introduced to address instability secondary to loss of posterior cruciate ligament function, and they have either fixed or mobile bearings. Mobile bearings were developed to improve the function and longevity of total knee prostheses. In this study, the International Consortium of Orthopaedic Registries used a distributed health data network to study a large cohort of posterior-stabilized prostheses to determine if the outcome of a posterior-stabilized total knee prosthesis differs depending on whether it has a fixed or mobile-bearing design. Methods: Aggregated registry data were collected with a distributed health data network that was developed by the International Consortium of Orthopaedic Registries to reduce barriers to participation (e.g., security, proprietary, legal, and privacy issues) that have the potential to occur with the alternate centralized data warehouse approach. A distributed health data network is a decentralized model that allows secure storage and analysis of data from different registries. Each registry provided data on mobile and fixed-bearing posterior-stabilized prostheses implanted between 2001 and 2010. Only prostheses associated with primary total knee arthroplasties performed for the treatment of osteoarthritis were included. Prostheses with all types of fixation were included except for those with the rarely used reverse hybrid (cementless tibial and cemented femoral components) fixation. The use of patellar resurfacing was reported. The outcome of interest was time to first revision (for any reason). Multivariate meta-analysis was performed with linear mixed models with survival probability as the unit of analysis. Results: This study includes 137,616 posterior-stabilized knee prostheses; 62% were in female patients, and 17.6% had a mobile bearing. The results of the fixed-effects model indicate that in the first year the mobile-bearing posterior-stabilized prostheses had a significantly higher hazard ratio (1.86) than did the fixed-bearing posterior-stabilized prostheses (95% confidence interval, 1.28 to 2.7; p = 0.001). For all other time intervals, the mobile-bearing posterior-stabilized prostheses had higher hazard ratios; however, these differences were not significant. Conclusions: Mobile-bearing posterior-stabilized prostheses had an increased rate of revision compared with fixed-bearing posterior-stabilized prostheses. This difference was evident in the first year. PMID:25520420

  1. Probability of causation approach

    SciTech Connect

    Jose, D.E.

    1988-08-01

    Probability of causation (PC) is sometimes viewed as a great improvement by those persons who are not happy with the present rulings of courts in radiation cases. The author does not share that hope and expects that PC will not play a significant role in these issues for at least the next decade. If it is ever adopted in a legislative compensation scheme, it will be used in a way that is unlikely to please most scientists. Consequently, PC is a false hope for radiation scientists, and its best contribution may well lie in some of the spin-off effects, such as an influence on medical practice.

  2. Imaging the posterior mediastinum: a multimodality approach

    PubMed Central

    Occhipinti, Mariaelena; Heidinger, Benedikt H.; Franquet, Elisa; Eisenberg, Ronald L.; Bankier, Alexander A.

    2015-01-01

    The posterior mediastinum contains several structures that can produce a wide variety of pathologic conditions. Descending thoracic aorta, esophagus, azygos and hemiazygos veins, thoracic duct, lymph nodes, adipose tissue, and nerves are all located in this anatomical region and can produce diverse abnormalities. Although chest radiography may detect many of these pathologic conditions, computed tomography and magnetic resonance are the imaging modalities of choice for further defining the relationship of posterior mediastinal lesions to neighboring structures and showing specific imaging features that narrow the differential diagnosis. This review emphasizes modality-related answers to morphologic questions, which provide precise diagnostic information. PMID:25993732

  3. Intraocular Nematode Affixed to Posterior Lens Capsule.

    PubMed

    Karth, Peter A; Swinney, Christian C; Moshfeghi, Darius M; Yannuzzi, Lawrence A; Pang, Claudine E; Leng, Theodore

    2015-01-01

    The clinical presentation of an intraocular nematode unusually affixed to the posterior lens capsule is described. A 64-year-old female patient presented with a 7-year history of gradually declining vision and enlarging central scotoma, but no inflammation. On follow-up 2 years later, vision had further declined and a non-motile, 8-mm nematode was seen affixed to the posterior lens capsule that remained unchanged through final follow-up. The patient disclosed having resided in Africa as a child. Systemic review revealed no evidence of extraocular involvement. Nematode carcasses may remain preserved in the human eye for extended periods without ongoing inflammation. PMID:26599254

  4. Posterior lumbar interbody fusion with facet-screw fixation.

    PubMed

    Stonecipher, T; Wright, S

    1989-04-01

    The optimal surgical construct for lumbar fusion remains controversial. The posterior lumbar interbody fusion (PLIF) operation offers advantages including total nuclear disc excision, restoration of disc-space height, root decompression, limited muscle retraction and injury, and solid mechanical arthrodesis. Major disadvantages have included graft displacement, neurologic injury and nonunion. The use of posterior fixation as an adjunct to PLIF reduces the probability of these complications and increases the chances of fusion. This study examines 35 patients who underwent PLIF and facet-screw fixation. Indications for surgery included disabling low-back pain with discographic/MRI-demonstrated disc derrangement, recurrent disc herniation, and failed inter-transverse process fusions. Follow-up ranged from 6 to 18 months. There were no patients with significant neurologic injury or functional root loss. One patient developed graft displacement and failure of fixation (laminar fracture in markedly obese patient). Three patients had subcutaneous hematomas (no surgical treatment required). None of the cases required blood replacement. The authors have concluded that the addition of facet fixation/fusion to the PLIF operation substantially reduces the complication rate of the procedure. PMID:2718053

  5. Posterior encephalopathy subsequent to cyclosporin A presenting as irreversible abulia.

    PubMed

    Nishie, Makoto; Kurahashi, Kozo; Ogawa, Masaya; Yoshida, Yasuji; Midorikawa, Hiroshi

    2003-08-01

    A case of cyclosporin A (Cys A)-induced posterior encephalopathy developed into persistent abulia despite rapid and marked improvement of abnormal T2- and FLAIR MRI hyperintense regions. Diffusion-weighted MRI signal intensity was also high at the onset. This change is atypical in Cys A-induced encephalopathy and was thought to predict poor recovery from the encephalopathy. Persistent abulia was probably due to marked hypoperfusion in the whole cortex including bilateral frontal lobes and basal ganglia as detected by SPECT. Apart from the breakdown of the blood-brain barrier, direct toxicity of Cys A to the brain may play a role in the pathogenesis of chronic, irreversible encephalopathy. PMID:12924507

  6. Popliteal pseudoaneurysm after arthroscopic posterior cruciate ligament reconstruction.

    PubMed

    van Dorp, Karin B; Breugem, Stefan J M; Driessen, Marcel J M

    2014-09-01

    This report presents the case of a 30-year-old motocross (BMX) cyclist with a third-degree posterior cruciate ligament rupture. The technique used for reconstruction was the transtibial single-bundle autologous hamstring technique. Unfortunately, the procedure was complicated by a popliteal pseudoaneurysm, which was located in line with the tibial canal. The pseudoaneurysm was treated with an end-to-end anastomosis and the patient recovered without further complaints. In this case, the popliteal artery was damaged most probably by the edge of the reamer or the guide wire during removal. Vascular complications can be limb- and life-threatening. This case report aims to increase the awareness of this serious complication with a review of the literature. PMID:25229050

  7. Identification of Bayesian posteriors for coefficients of chaos expansions

    SciTech Connect

    Arnst, M. Ghanem, R.; Soize, C.

    2010-05-01

    This article is concerned with the identification of probabilistic characterizations of random variables and fields from experimental data. The data used for the identification consist of measurements of several realizations of the uncertain quantities that must be characterized. The random variables and fields are approximated by a polynomial chaos expansion, and the coefficients of this expansion are viewed as unknown parameters to be identified. It is shown how the Bayesian paradigm can be applied to formulate and solve the inverse problem. The estimated polynomial chaos coefficients are hereby themselves characterized as random variables whose probability density function is the Bayesian posterior. This allows to quantify the impact of missing experimental information on the accuracy of the identified coefficients, as well as on subsequent predictions. An illustration in stochastic aeroelastic stability analysis is provided to demonstrate the proposed methodology.

  8. Poster error probability in the Mu-11 Sequential Ranging System

    NASA Technical Reports Server (NTRS)

    Coyle, C. W.

    1981-01-01

    An expression is derived for the posterior error probability in the Mu-2 Sequential Ranging System. An algorithm is developed which closely bounds the exact answer and can be implemented in the machine software. A computer simulation is provided to illustrate the improved level of confidence in a ranging acquisition using this figure of merit as compared to that using only the prior probabilities. In a simulation of 20,000 acquisitions with an experimentally determined threshold setting, the algorithm detected 90% of the actual errors and made false indication of errors on 0.2% of the acquisitions.

  9. Rupture of the posterior tibial tendon: CT and surgical findings.

    PubMed

    Rosenberg, Z S; Jahss, M H; Noto, A M; Shereff, M J; Cheung, Y; Frey, C C; Norman, A

    1988-05-01

    Computed tomography (CT) was performed in 42 patients with 49 clinically suspected tears of the posterior tibial tendon. Twenty-eight of the 49 suspected tears were subsequently surgically explored and repaired. Three patterns of tendon abnormalities were recognized on CT scans: type I-intact, hypertrophied, heterogeneous tendon; type II-attenuated tendon; and type III-absence of a portion of a tendon. Types I and II correlated with partial rupture seen during surgery, and type III correlated with complete rupture of the tendon. CT findings were accurate in 96% of the patients who underwent surgery. In four cases (14%), tendon rupture was seen on CT scans, but the extent of the injury was underestimated and the rupture was misclassified. Reactive periostitis of the distal tibia was seen in 71% of diseased tendons and may represent an important factor in the diagnosis of tendon rupture. PMID:3357960

  10. Probabilities for Solar Siblings

    NASA Astrophysics Data System (ADS)

    Valtonen, Mauri; Myllari, A.; Bobylev, V. V.; Bajkova, A.

    2013-05-01

    Abstract (2,250 Maximum Characters): We have shown previously (Bobylev et al. 2011) that some of the stars in the Solar neighborhood today may have originated in the same star cluster as the Sun, and could thus be called Solar Siblings. In this work we investigate the sensitivity of this result to Galactic models and to parameters of these models, and also extend the sample of orbits. There are a number of good candidates for the Sibling category, but due to the long period of orbit evolution since the break-up of the birth cluster of the Sun, one can only attach probabilities of membership. Bobylev,V.V., Bajkova, A.T., Mylläri, A. & Valtonen,M. 2011, Astronomy Letters 37, 550

  11. Probabilities for Solar Siblings

    NASA Astrophysics Data System (ADS)

    Valtonen, Mauri; Bajkova, A. T.; Bobylev, V. V.; Mylläri, A.

    2015-02-01

    We have shown previously (Bobylev et al. Astron Lett 37:550-562, 2011) that some of the stars in the solar neighborhood today may have originated in the same star cluster as the Sun, and could thus be called Solar Siblings. In this work we investigate the sensitivity of this result to galactic models and to parameters of these models, and also extend the sample of orbits. There are a number of good candidates for the sibling category, but due to the long period of orbit evolution since the break-up of the birth cluster of the Sun, one can only attach probabilities of membership. We find that up to 10 % (but more likely around 1 %) of the members of the Sun's birth cluster could be still found within 100 pc from the Sun today.

  12. Subspecialization in the human posterior medial cortex

    PubMed Central

    Bzdok, Danilo; Heeger, Adrian; Langner, Robert; Laird, Angela R.; Fox, Peter T.; Palomero-Gallagher, Nicola; Vogt, Brent A.; Zilles, Karl; Eickhoff, Simon B.

    2014-01-01

    The posterior medial cortex (PMC) is particularly poorly understood. Its neural activity changes have been related to highly disparate mental processes. We therefore investigated PMC properties with a data-driven exploratory approach. First, we subdivided the PMC by whole-brain coactivation profiles. Second, functional connectivity of the ensuing PMC regions was compared by task-constrained meta-analytic coactivation mapping (MACM) and task-unconstrained resting-state correlations (RSFC). Third, PMC regions were functionally described by forward/reverse functional inference. A precuneal cluster was mostly connected to the intraparietal sulcus, frontal eye fields, and right temporo-parietal junction; associated with attention and motor tasks. A ventral posterior cingulate cortex (PCC) cluster was mostly connected to the ventromedial prefrontal cortex and middle left inferior parietal cortex (IPC); associated with facial appraisal and language tasks. A dorsal PCC cluster was mostly connected to the dorsomedial prefrontal cortex, anterior/posterior IPC, posterior midcingulate cortex, and left dorsolateral prefrontal cortex; associated with delay discounting. A cluster in the retrosplenial cortex was mostly connected to the anterior thalamus and hippocampus. Furthermore, all PMC clusters were congruently coupled with the default mode network according to task-constrained but not task-unconstrained connectivity. We thus identified distinct regions in the PMC and characterized their neural networks and functional implications. PMID:25462801

  13. A Complication of Posterior Malleolar Fracture Fixation.

    PubMed

    Patel, Ankit; Charles, Loren; Ritchie, James

    2016-01-01

    We present a case of tibial nerve impingement by an anteroposterior screw inserted for stabilization of a posterior malleolar fracture. This specific complication has not previously been described in published studies, although numerous reports have described various forms of peripheral nerve entrapment. We discuss the merits of fixation of these fractures using a posterolateral approach. PMID:25907349

  14. Posterior arch defects of the cervical spine

    SciTech Connect

    Schwartz, A.M.; Wechsler, R.J.; Landy, M.D.; Wetzner, S.M.; Goldstein, S.A.

    1982-05-01

    Spondylolysis and absence of the pedicle are congenital anomalies of the posterior cervical spine. Their roentgenographic changes may be confused with other more serious entities which may necessitate either emergent therapy or require extensive diagnostic testing and treatment. Four cases are present and the literature is reviewed. A hypothesis for the embryologic etiology of these entities is proposed.

  15. Subspecialization in the human posterior medial cortex.

    PubMed

    Bzdok, Danilo; Heeger, Adrian; Langner, Robert; Laird, Angela R; Fox, Peter T; Palomero-Gallagher, Nicola; Vogt, Brent A; Zilles, Karl; Eickhoff, Simon B

    2015-02-01

    The posterior medial cortex (PMC) is particularly poorly understood. Its neural activity changes have been related to highly disparate mental processes. We therefore investigated PMC properties with a data-driven exploratory approach. First, we subdivided the PMC by whole-brain coactivation profiles. Second, functional connectivity of the ensuing PMC regions was compared by task-constrained meta-analytic coactivation mapping (MACM) and task-unconstrained resting-state correlations (RSFC). Third, PMC regions were functionally described by forward/reverse functional inference. A precuneal cluster was mostly connected to the intraparietal sulcus, frontal eye fields, and right temporo-parietal junction; associated with attention and motor tasks. A ventral posterior cingulate cortex (PCC) cluster was mostly connected to the ventromedial prefrontal cortex and middle left inferior parietal cortex (IPC); associated with facial appraisal and language tasks. A dorsal PCC cluster was mostly connected to the dorsomedial prefrontal cortex, anterior/posterior IPC, posterior midcingulate cortex, and left dorsolateral prefrontal cortex; associated with delay discounting. A cluster in the retrosplenial cortex was mostly connected to the anterior thalamus and hippocampus. Furthermore, all PMC clusters were congruently coupled with the default mode network according to task-unconstrained but not task-constrained connectivity. We thus identified distinct regions in the PMC and characterized their neural networks and functional implications. PMID:25462801

  16. Posterior predictive Bayesian phylogenetic model selection.

    PubMed

    Lewis, Paul O; Xie, Wangang; Chen, Ming-Hui; Fan, Yu; Kuo, Lynn

    2014-05-01

    We present two distinctly different posterior predictive approaches to Bayesian phylogenetic model selection and illustrate these methods using examples from green algal protein-coding cpDNA sequences and flowering plant rDNA sequences. The Gelfand-Ghosh (GG) approach allows dissection of an overall measure of model fit into components due to posterior predictive variance (GGp) and goodness-of-fit (GGg), which distinguishes this method from the posterior predictive P-value approach. The conditional predictive ordinate (CPO) method provides a site-specific measure of model fit useful for exploratory analyses and can be combined over sites yielding the log pseudomarginal likelihood (LPML) which is useful as an overall measure of model fit. CPO provides a useful cross-validation approach that is computationally efficient, requiring only a sample from the posterior distribution (no additional simulation is required). Both GG and CPO add new perspectives to Bayesian phylogenetic model selection based on the predictive abilities of models and complement the perspective provided by the marginal likelihood (including Bayes Factor comparisons) based solely on the fit of competing models to observed data. PMID:24193892

  17. The tapeworm's elusive antero-posterior polarity.

    PubMed

    Minelli, Alessandro

    2016-01-01

    Because of their sessile lifestyle and the lack of the sensory and feeding structures usually associated with the cephalic end, fixing the antero-posterior (AP) polarity of tapeworms is somewhat equivocal and has been a matter of century-long debates. Koziol et al. offer the first molecular evidence finally fixing the scolex as the animal's anterior pole. PMID:26965648

  18. Transition probabilities in Sm II via optical nutation

    NASA Astrophysics Data System (ADS)

    Kastberg, Anders; Villemoes, Petrine; Arnesen, Arne; Heijkenskjöld, Filip; Langereis, Alexander; Jungner, Peter; Linnæus, Staffan

    1993-12-01

    We have measured the transition probabilities for three lines in Sm II. The measurements are made by studying optical nutation with a fast Doppler switching technique in collinear laser spectroscopy on ion beams. The recorded nutation curves are fitted to a quantum-optical theoretical model, and the transition probabilities are extracted. For all three lines, the measured transition probabilities are more accurate than those of earlier published measurements.

  19. Direct probability mapping of contaminants

    SciTech Connect

    Rautman, C.A.

    1993-09-17

    Exhaustive characterization of a contaminated site is a physical and practical impossibility. Descriptions of the nature, extent, and level of contamination, as well as decisions regarding proposed remediation activities, must be made in a state of uncertainty based upon limited physical sampling. Geostatistical simulation provides powerful tools for investigating contaminant levels, and in particular, for identifying and using the spatial interrelationships among a set of isolated sample values. This additional information can be used to assess the likelihood of encountering contamination at unsampled locations and to evaluate the risk associated with decisions to remediate or not to remediate specific regions within a site. Past operation of the DOE Feed Materials Production Center has contaminated a site near Fernald, Ohio, with natural uranium. Soil geochemical data have been collected as part of the Uranium-in-Soils Integrated Demonstration Project. These data have been used to construct a number of stochastic images of potential contamination for parcels approximately the size of a selective remediation unit. Each such image accurately reflects the actual measured sample values, and reproduces the univariate statistics and spatial character of the extant data. Post-processing of a large number of these equally likely, statistically similar images produces maps directly showing the probability of exceeding specified levels of contamination. Evaluation of the geostatistical simulations can yield maps representing the expected magnitude of the contamination for various regions and other information that may be important in determining a suitable remediation process or in sizing equipment to accomplish the restoration.

  20. An Unusual Cause of Posterior Elbow Impingement: Detachment of a Hypertrophied Posterior Fat Pad

    PubMed Central

    Hamada, Daisuke; Matsuura, Tetsuya; Sugiura, Kosuke; Higuchi, Tadahiro; Suzue, Naoto; Goto, Tomohiro; Tsutsui, Takahiko; Wada, Keizo; Fukuta, Shoji; Sairyo, Koichi

    2015-01-01

    We report a case of a 47-year-old woman who developed posterior impingement of the elbow due to detachment of a hypertrophied posterior fat pad. She reported acute left elbow pain after leaning back onto a hard object with her hand and subsequently experienced a “catching” sensation. Comparison with the magnetic resonance images of a normal elbow revealed a hypertrophied posterior fat pad interposed between the olecranon and olecranon fossa in both elbows, with the fat pad in the left elbow located more inferiorly than that in the right elbow. Elbow arthroscopy showed the olecranon fossa covered by the fat pad, a portion of which was detached from the rest of the pad. Debridement of the detached portion was performed until no impingement was evident. Postoperatively, full extension of the elbow did not elicit pain. Clinicians should include this pathology among the differential diagnoses for posterior elbow pain. PMID:26613057

  1. Probability distributions for magnetotellurics

    SciTech Connect

    Stodt, John A.

    1982-11-01

    Estimates of the magnetotelluric transfer functions can be viewed as ratios of two complex random variables. It is assumed that the numerator and denominator are governed approximately by a joint complex normal distribution. Under this assumption, probability distributions are obtained for the magnitude, squared magnitude, logarithm of the squared magnitude, and the phase of the estimates. Normal approximations to the distributions are obtained by calculating mean values and variances from error propagation, and the distributions are plotted with their normal approximations for different percentage errors in the numerator and denominator of the estimates, ranging from 10% to 75%. The distribution of the phase is approximated well by a normal distribution for the range of errors considered, while the distribution of the logarithm of the squared magnitude is approximated by a normal distribution for a much larger range of errors than is the distribution of the squared magnitude. The distribution of the squared magnitude is most sensitive to the presence of noise in the denominator of the estimate, in which case the true distribution deviates significantly from normal behavior as the percentage errors exceed 10%. In contrast, the normal approximation to the distribution of the logarithm of the magnitude is useful for errors as large as 75%.

  2. Posterior Wnts Have Distinct Roles in Specification and Patterning of the Planarian Posterior Region

    PubMed Central

    Sureda-Gómez, Miquel; Pascual-Carreras, Eudald; Adell, Teresa

    2015-01-01

    The wnt signaling pathway is an intercellular communication mechanism essential in cell-fate specification, tissue patterning and regional-identity specification. A βcatenin-dependent signal specifies the AP (Anteroposterior) axis of planarians, both during regeneration of new tissues and during normal homeostasis. Accordingly, four wnts (posterior wnts) are expressed in a nested manner in central and posterior regions of planarians. We have analyzed the specific role of each posterior wnt and the possible cooperation between them in specifying and patterning planarian central and posterior regions. We show that each posterior wnt exerts a distinct role during re-specification and maintenance of the central and posterior planarian regions, and that the integration of the different wnt signals (βcatenin dependent and independent) underlies the patterning of the AP axis from the central region to the tip of the tail. Based on these findings and data from the literature, we propose a model for patterning the planarian AP axis. PMID:26556349

  3. Posterior Wnts Have Distinct Roles in Specification and Patterning of the Planarian Posterior Region.

    PubMed

    Sureda-Gómez, Miquel; Pascual-Carreras, Eudald; Adell, Teresa

    2015-01-01

    The wnt signaling pathway is an intercellular communication mechanism essential in cell-fate specification, tissue patterning and regional-identity specification. A βcatenin-dependent signal specifies the AP (Anteroposterior) axis of planarians, both during regeneration of new tissues and during normal homeostasis. Accordingly, four wnts (posterior wnts) are expressed in a nested manner in central and posterior regions of planarians. We have analyzed the specific role of each posterior wnt and the possible cooperation between them in specifying and patterning planarian central and posterior regions. We show that each posterior wnt exerts a distinct role during re-specification and maintenance of the central and posterior planarian regions, and that the integration of the different wnt signals (βcatenin dependent and independent) underlies the patterning of the AP axis from the central region to the tip of the tail. Based on these findings and data from the literature, we propose a model for patterning the planarian AP axis. PMID:26556349

  4. Posterior Pole Sparing Laser Photocoagulation Combined with Intravitreal Bevacizumab Injection in Posterior Retinopathy of Prematurity

    PubMed Central

    Kim, Rebecca; Kim, Yu Cheol

    2014-01-01

    Purpose. To report the results of the posterior pole sparing laser photocoagulation combined with intravitreal bevacizumab injection (IVB) in retinopathy of prematurity (ROP). Methods. A retrospective chart review of premature babies with ROP, all of whom received laser photocoagulation with IVB. Eleven eyes of 6 infants with advanced zone I ROP underwent laser ablation sparing posterior pole with concurrent IVB. The results were compared with those of full-laser treatment combined with IVB to 8 eyes of 5 infants with advanced ROP without involvement of the posterior pole. Results. The posterior pole sparing laser with IVB was performed with zone I, stage 3+ ROP at the mean postmenstrual age of 36 weeks and 5 days. The plus sign decreased significantly at postoperative day 1, the neovascular proliferation regressed by postoperative week 1, and the normal vascularization started at postoperative day 32 on the average. Two months after treatment, vascularization of the spared avascular area was completed. There was no macular dragging, tractional retinal detachment, foveal destruction by laser scars, or any other adverse event. No significant anatomical differences were identified from those of full-laser ablation combined with IVB. Conclusions. Posterior pole sparing laser with IVB can give favorable results without destruction of posterior pole retina. PMID:25614828

  5. Approximation of Failure Probability Using Conditional Sampling

    NASA Technical Reports Server (NTRS)

    Giesy. Daniel P.; Crespo, Luis G.; Kenney, Sean P.

    2008-01-01

    In analyzing systems which depend on uncertain parameters, one technique is to partition the uncertain parameter domain into a failure set and its complement, and judge the quality of the system by estimating the probability of failure. If this is done by a sampling technique such as Monte Carlo and the probability of failure is small, accurate approximation can require so many sample points that the computational expense is prohibitive. Previous work of the authors has shown how to bound the failure event by sets of such simple geometry that their probabilities can be calculated analytically. In this paper, it is shown how to make use of these failure bounding sets and conditional sampling within them to substantially reduce the computational burden of approximating failure probability. It is also shown how the use of these sampling techniques improves the confidence intervals for the failure probability estimate for a given number of sample points and how they reduce the number of sample point analyses needed to achieve a given level of confidence.

  6. Fusion probability in heavy nuclei

    NASA Astrophysics Data System (ADS)

    Banerjee, Tathagata; Nath, S.; Pal, Santanu

    2015-03-01

    Background: Fusion between two massive nuclei is a very complex process and is characterized by three stages: (a) capture inside the potential barrier, (b) formation of an equilibrated compound nucleus (CN), and (c) statistical decay of the CN leading to a cold evaporation residue (ER) or fission. The second stage is the least understood of the three and is the most crucial in predicting yield of superheavy elements (SHE) formed in complete fusion reactions. Purpose: A systematic study of average fusion probability, , is undertaken to obtain a better understanding of its dependence on various reaction parameters. The study may also help to clearly demarcate onset of non-CN fission (NCNF), which causes fusion probability, PCN, to deviate from unity. Method: ER excitation functions for 52 reactions leading to CN in the mass region 170-220, which are available in the literature, have been compared with statistical model (SM) calculations. Capture cross sections have been obtained from a coupled-channels code. In the SM, shell corrections in both the level density and the fission barrier have been included. for these reactions has been extracted by comparing experimental and theoretical ER excitation functions in the energy range ˜5 %-35% above the potential barrier, where known effects of nuclear structure are insignificant. Results: has been shown to vary with entrance channel mass asymmetry, η (or charge product, ZpZt ), as well as with fissility of the CN, χCN. No parameter has been found to be adequate as a single scaling variable to determine . Approximate boundaries have been obtained from where starts deviating from unity. Conclusions: This study quite clearly reveals the limits of applicability of the SM in interpreting experimental observables from fusion reactions involving two massive nuclei. Deviation of from unity marks the beginning of the domain of dynamical models of fusion. Availability of precise ER cross sections over a wider energy range for many more reactions is desired for accurate determination of and more insight into the dynamics of fusion in the heavy mass region.

  7. Shining a light on posterior cortical atrophy.

    PubMed

    Crutch, Sebastian J; Schott, Jonathan M; Rabinovici, Gil D; Boeve, Bradley F; Cappa, Stefano F; Dickerson, Bradford C; Dubois, Bruno; Graff-Radford, Neill R; Krolak-Salmon, Pierre; Lehmann, Manja; Mendez, Mario F; Pijnenburg, Yolande; Ryan, Natalie S; Scheltens, Philip; Shakespeare, Tim; Tang-Wai, David F; van der Flier, Wiesje M; Bain, Lisa; Carrillo, Maria C; Fox, Nick C

    2013-07-01

    Posterior cortical atrophy (PCA) is a clinicoradiologic syndrome characterized by progressive decline in visual processing skills, relatively intact memory and language in the early stages, and atrophy of posterior brain regions. Misdiagnosis of PCA is common, owing not only to its relative rarity and unusual and variable presentation, but also because patients frequently first seek the opinion of an ophthalmologist, who may note normal eye examinations by their usual tests but may not appreciate cortical brain dysfunction. Seeking to raise awareness of the disease, stimulate research, and promote collaboration, a multidisciplinary group of PCA research clinicians formed an international working party, which had its first face-to-face meeting on July 13, 2012 in Vancouver, Canada, prior to the Alzheimer's Association International Conference. PMID:23274153

  8. Posterior fossa lesions associated with neuropsychiatric symptomatology.

    PubMed

    Pollak, L; Klein, C; Rabey, J M; Schiffer, J

    1996-11-01

    We reviewed 7 cases with posterior fossa structural abnormalities (3 tumors, 2 megacisterna magna and 2 Dandy-Walker syndrome) presenting with neuropsychiatric symptomatology. Derangement in the balance of dopamine, serotonin and noradrenergic networks has been implicated in the pathogenesis of schizophrenia, affective and even personality disorders. Disruption of the cerebellar output to mesial dopaminergic areas, locus coeruleus and raphe nuclei, or deafferentation of the thalamolimbic circuits by a cerebellar lesion may lead to behavioral changes. Seven patients (pts) (comprising 4 men and 3 women with mean age 22 years) were diagnosed as suffering from psychosis (2 pts), major depression (1 pt), personality disorders (2 pts) and somatoform disorders (2 pts) (DSM-IV criteria). Brain CT scan (7 pts) and MRI (4 pts) revealed tumors of the posterior fossa (2 pts), megacisterna magna (2 pts) and Dandy-Walker variant (2 pts). In one patient a IVth ventricle tumor was removed in childhood. PMID:9003973

  9. Posterior Vertebral Injury; Is This a Burst Fracture or a Flexion-Distraction Injury?

    PubMed Central

    Omidi-Kashani, Farzad

    2014-01-01

    In thoracolumbar spinal fractures with posterior column injury for applying proper management, it is important to distinguish a flexion-distraction injury (FDI) from a three column burst fracture (BF) as in clinical examination, both may have a similar significant tenderness on direct spinal palpation. Careful attention to the comprehensive clinical examination and detailed imaging features are essential in making an accurate diagnosis and thus appropriate treatment. PMID:25207330

  10. The mechanism of continence after posterior urethroplasty

    PubMed Central

    Bagga, Herman S.; Angermeier, Kenneth W.

    2015-01-01

    The standard of care after a pelvic fracture urethral injury is a repair via a one-stage anastomotic posterior urethroplasty using a step-wise perineal approach. The initial injury, immediate postoperative management, and surgical repair can all affect urinary continence in these patients. Proximal continence mechanisms, particularly the bladder neck, are particularly important in maintaining urinary continence in these patients. Patients with bladder neck dysfunction should be counselled about the greater risk of urinary incontinence. PMID:26019981

  11. Cervical disc hernia operations through posterior laminoforaminotomy

    PubMed Central

    Yolas, Coskun; Ozdemir, Nuriye Guzin; Okay, Hilmi Onder; Kanat, Ayhan; Senol, Mehmet; Atci, Ibrahim Burak; Yilmaz, Hakan; Coban, Mustafa Kemal; Yuksel, Mehmet Onur; Kahraman, Umit

    2016-01-01

    Objective: The most common used technique for posterolateral cervical disc herniations is anterior approach. However, posterior cervical laminotoforaminomy can provide excellent results in appropriately selected patients with foraminal stenosis in either soft disc prolapse or cervical spondylosis. The purpose of this study was to present the clinical outcomes following posterior laminoforaminotomy in patients with radiculopathy. Materials and Methods: We retrospectively evaluated 35 patients diagnosed with posterolateral cervical disc herniation and cervical spondylosis with foraminal stenosis causing radiculopathy operated by the posterior cervical keyhole laminoforaminotomy between the years 2010 and 2015. Results: The file records and the radiographic images of the 35 patients were assessed retrospectively. The mean age was 46.4 years (range: 34-66 years). Of the patients, 19 were males and 16 were females. In all of the patients, the neurologic deficit observed was radiculopathy. The posterolaterally localized disc herniations and the osteophytic structures were on the left side in 18 cases and on the right in 17 cases. In 10 of the patients, the disc level was at C5-6, in 18 at C6-7, in 2 at C3-4, in 2 at C4-5, in 1 at C7-T1, in 1 patient at both C5-6 and C6-7, and in 1 at both C4-5 and C5-6. In 14 of these 35 patients, both osteophytic structures and protruded disc herniation were present. Intervertebral foramen stenosis was present in all of the patients with osteophytes. Postoperatively, in 31 patients the complaints were relieved completely and four patients had complaints of neck pain and paresthesia radiating to the arm (the success of operation was 88.5%). On control examinations, there was no finding of instability or cervical kyphosis. Conclusion: Posterior cervical laminoforaminotomy is an alternative appropriate choice in both cervical soft disc herniations and cervical stenosis. PMID:27217655

  12. A Tale of Two Probabilities

    ERIC Educational Resources Information Center

    Falk, Ruma; Kendig, Keith

    2013-01-01

    Two contestants debate the notorious probability problem of the sex of the second child. The conclusions boil down to explication of the underlying scenarios and assumptions. Basic principles of probability theory are highlighted.

  13. Recurrent posterior shoulder instability after rifle shooting.

    PubMed

    Cho, Jae-Ho; Chung, Nam-Su; Song, Hyung-Keun; Lee, Doo-Hyung

    2012-11-01

    Rifle shooting produces a sudden counterforce against the body thorough the anterior shoulder, which may produce a traumatic injury in soldiers. Posterior instability of the shoulder can occur in soldiers who practice rifle shooting. To the authors' knowledge, few reports have examined shooting-related injuries in soldiers. This article describes the case of a 27-year-old male soldier who presented with left shoulder pain and instability after rifle training. He developed symptoms, and presented radiographic findings consistent with a posterior Bankart lesion. Intraoperatively, while in the lateral decubitus position, a posterior portal was created 3 cm inferior and 2 cm lateral to the posterolateral corner of acromion for making a proper angle for inserting anchors. A reverse bony Bankart lesion and adjacent cartilage breakdown at the glenoid rim were noted. An arthroscopic capsulolabral repair was performed with 3-mm bioabsorbable anchors to the glenoid rim. No gross reverse Hill-Sachs lesion or hyaline cartilage lesion was noted. Postoperatively, the arm was supported in a sling with an abduction pillow for 5 weeks. Codman's exercises, scapular protraction exercises, and elbow and wrist exercises were started. Physical therapy focused on reestablishing glenohumeral range of motion and rotator cuff and periscapular muscle strength. Six months postoperatively, the patient had normal scapular kinesis and reported no shoulder pain or symptoms of instability associated with a reverse bony Bankart lesion. PMID:23127465

  14. Evolution of the posterior petrosal approach.

    PubMed

    Gross, Bradley A; Tavanaiepour, Daryoush; Du, Rose; Al-Mefty, Ossama; Dunn, Ian F

    2012-08-01

    In this article, the authors review the history of the posterior petrosal approach. The early foundation of the retrolabyrinthine lateral petrosectomy has its roots in the otolaryngology literature. These early approaches were limited in exposure by the tentorium superiorly and the sigmoid sinus posteriorly. Although the concept of a transtentorial approach was originally combined with a complete labyrinthectomy, Hakuba and colleagues described the expansive exposure afforded by sectioning the tentorium and superior petrosal sinus and mobilizing a skeletonized sigmoid sinus. This maneuver serves as the key step in allowing for the full, combined supra- and infratentorial exposure that the posterior petrosal approach provides. In contrast to Hakuba et al.'s approach, which used a partial labyrinthectomy, modern approaches often preserve the entire labyrinth (retrolabyrinthine approach). For added exposure, the latter can be combined with the anterior petrosal approach, allowing for the preservation of hearing and an enhanced view of the surgical target. The authors review the evolution of the petrosal approach and highlight its applicability. PMID:22853838

  15. Air bag associated posterior segment ocular trauma.

    PubMed

    Yang, Chang-Sue; Chou, Tzu-Fang; Liu, Jorn-Hon; Hsu, Wen-Ming

    2004-08-01

    Airbags indeed reduce the risk of injury and death in motor vehicle accidents, however, ocular injury induced by airbag deployment has been reported. From 1999 to 2001, medical records were retrospectively reviewed for patients with severe ocular injury related to airbag inflation at Taipei Veterans General Hospital. The ocular presentation, clinical course, management and visual outcome were recorded and studied in detail. Three cases of ocular posterior segment injury associated with airbag inflation were identified. Mean age was 37.3 years old (range 34-39 years). None of the patients was wearing a seat belt. All patients had periocular contusion, corneal edema, and hyphema. Vitreous hemorrhage was found in 3 cases, and there were 2 cases with severe macular injury, including traumatic maculopathy and hypotony maculopathy. Retinal detachment developed in 1 case. One patient presented with traumatic macular hole 6 weeks after injury. The initial visual acuity was hand motion only in all patients, the final visual outcomes recovered to 6/20, 1/60 and 2/60, respectively. The airbag-associated posterior segment ocular trauma was induced by impact with fully deployed airbag. Severe ocular posterior segment trauma with devastating visual sequelae might occur in drivers and passengers who have not fastened their seat belt. PMID:15553805

  16. Approaching system equilibrium with accurate or not accurate feedback information in a two-route system

    NASA Astrophysics Data System (ADS)

    Zhao, Xiao-mei; Xie, Dong-fan; Li, Qi

    2015-02-01

    With the development of intelligent transport system, advanced information feedback strategies have been developed to reduce traffic congestion and enhance the capacity. However, previous strategies provide accurate information to travelers and our simulation results show that accurate information brings negative effects, especially in delay case. Because travelers prefer to the best condition route with accurate information, and delayed information cannot reflect current traffic condition but past. Then travelers make wrong routing decisions, causing the decrease of the capacity and the increase of oscillations and the system deviating from the equilibrium. To avoid the negative effect, bounded rationality is taken into account by introducing a boundedly rational threshold BR. When difference between two routes is less than the BR, routes have equal probability to be chosen. The bounded rationality is helpful to improve the efficiency in terms of capacity, oscillation and the gap deviating from the system equilibrium.

  17. The Probability of Causal Conditionals

    ERIC Educational Resources Information Center

    Over, David E.; Hadjichristidis, Constantinos; Evans, Jonathan St. B. T.; Handley, Simon J.; Sloman, Steven A.

    2007-01-01

    Conditionals in natural language are central to reasoning and decision making. A theoretical proposal called the Ramsey test implies the conditional probability hypothesis: that the subjective probability of a natural language conditional, P(if p then q), is the conditional subjective probability, P(q [such that] p). We report three experiments on

  18. The Probability of Causal Conditionals

    ERIC Educational Resources Information Center

    Over, David E.; Hadjichristidis, Constantinos; Evans, Jonathan St. B. T.; Handley, Simon J.; Sloman, Steven A.

    2007-01-01

    Conditionals in natural language are central to reasoning and decision making. A theoretical proposal called the Ramsey test implies the conditional probability hypothesis: that the subjective probability of a natural language conditional, P(if p then q), is the conditional subjective probability, P(q [such that] p). We report three experiments on…

  19. Probability Forecasting Using Monte Carlo Simulation

    NASA Astrophysics Data System (ADS)

    Duncan, M.; Frisbee, J.; Wysack, J.

    2014-09-01

    Space Situational Awareness (SSA) is defined as the knowledge and characterization of all aspects of space. SSA is now a fundamental and critical component of space operations. Increased dependence on our space assets has in turn lead to a greater need for accurate, near real-time knowledge of all space activities. With the growth of the orbital debris population, satellite operators are performing collision avoidance maneuvers more frequently. Frequent maneuver execution expends fuel and reduces the operational lifetime of the spacecraft. Thus the need for new, more sophisticated collision threat characterization methods must be implemented. The collision probability metric is used operationally to quantify the collision risk. The collision probability is typically calculated days into the future, so that high risk and potential high risk conjunction events are identified early enough to develop an appropriate course of action. As the time horizon to the conjunction event is reduced, the collision probability changes. A significant change in the collision probability will change the satellite mission stakeholder's course of action. So constructing a method for estimating how the collision probability will evolve improves operations by providing satellite operators with a new piece of information, namely an estimate or 'forecast' of how the risk will change as time to the event is reduced. Collision probability forecasting is a predictive process where the future risk of a conjunction event is estimated. The method utilizes a Monte Carlo simulation that produces a likelihood distribution for a given collision threshold. Using known state and state uncertainty information, the simulation generates a set possible trajectories for a given space object pair. Each new trajectory produces a unique event geometry at the time of close approach. Given state uncertainty information for both objects, a collision probability value can be computed for every trail. This yields a collision probability distribution given known, predicted uncertainty. This paper presents the details of the collision probability forecasting method. We examine various conjunction event scenarios and numerically demonstrate the utility of this approach in typical event scenarios. We explore the utility of a probability-based track scenario simulation that models expected tracking data frequency as the tasking levels are increased. The resulting orbital uncertainty is subsequently used in the forecasting algorithm.

  20. Electrocardiographic diagnosis of remote posterior wall myocardial infarction using unipolar posterior lead V9

    SciTech Connect

    Rich, M.W.; Imburgia, M.; King, T.R.; Fischer, K.C.; Kovach, K.L. )

    1989-09-01

    The accuracy of four electrocardiographic criteria for diagnosing remote posterior myocardial infarction was assessed prospectively in 369 patients undergoing exercise treadmill testing with thallium scintigraphy. Criteria included the following: (1) R-wave width greater than or equal to 0.04 s and R-wave greater than or equal to S-wave in V1; (2) R-wave greater than or equal to S-wave in V2; (3) T-wave voltage in V2 minus V6 greater than or equal to 0.38 mV (T-wave index); (4) Q-wave greater than or equal to 0.04 s in left paraspinal lead V9. Twenty-seven patients (7.3 percent) met thallium criteria for posterior myocardial infarction, defined as a persistent perfusion defect in the posterobase of the left ventricle. Sensitivities for the four criteria ranged from 4 to 56 percent, and specificities ranged from 64 to 99 percent. Posterior paraspinal lead V9 provided the best overall predictive accuracy (94 percent), positive predictive value (58 percent), and ability to differentiate patients with and without posterior myocardial infarction of any single criterion (p less than .0001). Combining the T-wave index with lead V9 further enhanced the diagnostic yield: the sensitivity for detecting posterior infarction by at least one of these criteria was 78 percent, and when both criteria were positive, specificity was 98.5 percent. It is concluded that a single, unipolar posterior lead in the V9 position is superior to standard 12-lead electrocardiographic criteria in diagnosing remote posterior myocardial infarction, and that combining V9 with the T-wave index maximizes the diagnostic yield.

  1. Controversies in posterior composite resin restorations.

    PubMed

    Wilson, E G; Mandradjieff, M; Brindock, T

    1990-01-01

    The use of posterior composites is riddled with so many controversies that the puzzled practitioner must step warily among them. This modality is a minefield, where one careless movement can bring disaster. All composite restorations are subject to three big destructive forces--moisture, polymerization shrinkage, and clinical wear--forces that can eventually produce both microleakage and deterioration of the silane coupling agent linking filler particles to resin matrix. Despite the extreme technique sensitivity of posterior composite resins, knowledge of resin technology, sound operative dentistry principles and foresight in case selection can be effective in producing durable cosmetic restorations. Posterior composite resin restorations bonded to enamel and dentin reputedly strengthen teeth in both conventional and adhesive types of preparations provided polymerization shrinkage can be controlled. It is imperative that a knowledge of occlusal contacts be used to influence cavity outline, confining the trauma or occlusal forces away from the tooth-resin interface and helping to minimize occlusal wear. With the increased use of posterior resins, the trend in cavity preparations should break away from the traditional Black preparation toward the adhesive type preparation. If the Black Class II preparation is used, it is suggested that bevels be confined to the facial and lingual margins of the proximal box. Prewedging helps to maintain a conservative Class II preparation. Shade selection must be made prior to rubber dam isolation for greater accuracy and to help prevent postinsertion discoloration. The enamel should be pumiced to present a clean substrate for acid etching. The smear layer should be removed. The type of pulp protection applied before acid etching is dependent on the material used. After etching, the enamel should be washed with a 1 per cent potassium chloride solution. It is a more universally chemically stable solution than additive-laden local water supplies. The potassium chloride solution lowers the electrostatic forces on the enamel that would interfere with the flow of enamel bonding agents. Furthermore, tests have shown that the use of potassium chloride washes increase the strength of the enamel body by 40 per cent. Because of the depth of most posterior cavities, an incremental filling technique must be used to ensure a thorough polymerization of the resin and to forestall a massive polymerization shrinkage. When finished and contoured, the margins of the restoration should be re-etched, washed, and dried and then covered with an application of unfilled resin to discourage microleakage. Traditional operative dentistry technique must become flexible enough to meet the new demands of resin technology.(ABSTRACT TRUNCATED AT 400 WORDS) PMID:2403943

  2. The diagnostic dilemma of the posterior mediastinal thymus: CT manifestations

    SciTech Connect

    Cohen, M.D.; Weber, T.R.; Sequeira, F.W.; Vane, D.W.; King, H.

    1983-03-01

    Extension of the normal thymus into the posterior mediastinum is rare. The CT appearance of this anomaly in an infant is presented. A mass of soft-tissue density extended from the anterior mediastinum to the posterior chest wall. The absence of any tissue-cleavage plane in the lesion and a smooth continuous lateral margin are signs of posterior extension of the thymus, and they help to distinguish this from a normal anterior thymus being present with a posterior tumor.

  3. Peripapillary and posterior scleral mechanics--part I: development of an anisotropic hyperelastic constitutive model.

    PubMed

    Girard, Michaël J A; Downs, J Crawford; Burgoyne, Claude F; Suh, J-K Francis

    2009-05-01

    The sclera is the white outer shell and principal load-bearing tissue of the eye as it sustains the intraocular pressure. We have hypothesized that the mechanical properties of the posterior sclera play a significant role in and are altered by the development of glaucoma-an ocular disease manifested by structural damage to the optic nerve head. An anisotropic hyperelastic constitutive model is presented to simulate the mechanical behavior of the posterior sclera under acute elevations of intraocular pressure. The constitutive model is derived from fiber-reinforced composite theory, and incorporates stretch-induced stiffening of the reinforcing collagen fibers. Collagen fiber alignment was assumed to be multidirectional at local material points, confined within the plane tangent to the scleral surface, and described by the semicircular von Mises distribution. The introduction of a model parameter, namely, the fiber concentration factor, was used to control collagen fiber alignment along a preferred fiber orientation. To investigate the effects of scleral collagen fiber alignment on the overall behaviors of the posterior sclera and optic nerve head, finite element simulations of an idealized eye were performed. The four output quantities analyzed were the scleral canal expansion, the scleral canal twist, the posterior scleral canal deformation, and the posterior laminar deformation. A circumferential fiber organization in the sclera restrained scleral canal expansion but created posterior laminar deformation, whereas the opposite was observed with a meridional fiber organization. Additionally, the fiber concentration factor acted as an amplifying parameter on the considered outputs. The present model simulation suggests that the posterior sclera has a large impact on the overall behavior of the optic nerve head. It is therefore primordial to provide accurate mechanical properties for this tissue. In a companion paper (Girard, Downs, Bottlang, Burgoyne, and Suh, 2009, "Peripapillary and Posterior Scleral Mechanics--Part II: Experimental and Inverse Finite Element Characterization," ASME J. Biomech. Eng., 131, p. 051012), we present a method to measure the 3D deformations of monkey posterior sclera and extract mechanical properties based on the proposed constitutive model with an inverse finite element method. PMID:19388781

  4. Peripapillary and posterior scleral mechanics--part II: experimental and inverse finite element characterization.

    PubMed

    Girard, Michaël J A; Downs, J Crawford; Bottlang, Michael; Burgoyne, Claude F; Suh, J-K Francis

    2009-05-01

    The posterior sclera likely plays an important role in the development of glaucoma, and accurate characterization of its mechanical properties is needed to understand its impact on the more delicate optic nerve head--the primary site of damage in the disease. The posterior scleral shells from both eyes of one rhesus monkey were individually mounted on a custom-built pressurization apparatus. Intraocular pressure was incrementally increased from 5 mm Hg to 45 mm Hg, and the 3D displacements were measured using electronic speckle pattern interferometry. Finite element meshes of each posterior scleral shell were reconstructed from data generated by a 3D digitizer arm (shape) and a 20 MHz ultrasound transducer (thickness). An anisotropic hyperelastic constitutive model described in a companion paper (Girard, Downs, Burgoyne, and Suh, 2009, "Peripapillary and Posterior Scleral Mechanics--Part I: Development of an Anisotropic Hyperelastic Constitutive Model," ASME J. Biomech. Eng., 131, p. 051011), which includes stretch-induced stiffening and multidirectional alignment of the collagen fibers, was applied to each reconstructed mesh. Surface node displacements of each model were fitted to the experimental displacements using an inverse finite element method, which estimated a unique set of 13 model parameters. The predictions of the proposed constitutive model matched the 3D experimental displacements well. In both eyes, the tangent modulus increased dramatically with IOP, which indicates that the sclera is mechanically nonlinear. The sclera adjacent to the optic nerve head, known as the peripapillary sclera, was thickest and exhibited the lowest tangent modulus, which might have contributed to the uniform distribution of the structural stiffness for each entire scleral shell. Posterior scleral deformation following acute IOP elevations appears to be nonlinear and governed by the underlying scleral collagen microstructure as predicted by finite element modeling. The method is currently being used to characterize posterior scleral mechanics in normal (young and old), early, and moderately glaucomatous monkey eyes. PMID:19388782

  5. Probability workshop to be better in probability topic

    NASA Astrophysics Data System (ADS)

    Asmat, Aszila; Ujang, Suriyati; Wahid, Sharifah Norhuda Syed

    2015-02-01

    The purpose of the present study was to examine whether statistics anxiety and attitudes towards probability topic among students in higher education level have an effect on their performance. 62 fourth semester science students were given statistics anxiety questionnaires about their perception towards probability topic. Result indicated that students' performance in probability topic is not related to anxiety level, which means that the higher level in statistics anxiety will not cause lower score in probability topic performance. The study also revealed that motivated students gained from probability workshop ensure that their performance in probability topic shows a positive improvement compared before the workshop. In addition there exists a significance difference in students' performance between genders with better achievement among female students compared to male students. Thus, more initiatives in learning programs with different teaching approaches is needed to provide useful information in improving student learning outcome in higher learning institution.

  6. Propensity, Probability, and Quantum Theory

    NASA Astrophysics Data System (ADS)

    Ballentine, Leslie E.

    2016-02-01

    Quantum mechanics and probability theory share one peculiarity. Both have well established mathematical formalisms, yet both are subject to controversy about the meaning and interpretation of their basic concepts. Since probability plays a fundamental role in QM, the conceptual problems of one theory can affect the other. We first classify the interpretations of probability into three major classes: (a) inferential probability, (b) ensemble probability, and (c) propensity. Class (a) is the basis of inductive logic; (b) deals with the frequencies of events in repeatable experiments; (c) describes a form of causality that is weaker than determinism. An important, but neglected, paper by P. Humphreys demonstrated that propensity must differ mathematically, as well as conceptually, from probability, but he did not develop a theory of propensity. Such a theory is developed in this paper. Propensity theory shares many, but not all, of the axioms of probability theory. As a consequence, propensity supports the Law of Large Numbers from probability theory, but does not support Bayes theorem. Although there are particular problems within QM to which any of the classes of probability may be applied, it is argued that the intrinsic quantum probabilities (calculated from a state vector or density matrix) are most naturally interpreted as quantum propensities. This does not alter the familiar statistical interpretation of QM. But the interpretation of quantum states as representing knowledge is untenable. Examples show that a density matrix fails to represent knowledge.

  7. Surgical options for posterior tibial plateau fracture

    PubMed Central

    Chen, Hongwei; Wu, Lijun

    2015-01-01

    Objective: To investigate surgical methods and clinical effectiveness of posteromedial and posterolateral approaches for the posterior tibial plateau fracture. Method: 21 cases who received surgery through posterior approaches for the treatment of posterior tibial plateau fractures (PTPFs) were included. Results: 21 cases were subject to follow-up for 12-24 months (an average of 16.2 months). No cases developed incision inflammation, neurovascular injury, internal fixation loosening and breakage. All fractures were healed. No cases developed knee varus and valgus deformity and fracture dislocation. After surgery, Rasmussen score for knee joint functions was 13-30 points (a mean of 24.2). The results were excellent in 12 cases, good in 7 cases and fair in 2 cases. The percentage of excellent and good results was 90.5%. Rasmussen radiology score was 10-18 points (a mean of 15.6 points). The results were excellent in 13 cases, good in 7 cases and fair in 1 cases. The percentage of excellent and good results was 95.2%. 1 case had significant limited range of knee flexion and extension, which was improved after phase II release under arthroscopy combined with function exercise. 2 cases developed traumatic arthritis, which was relieved after intra-articular injection with sodium hyaluronate and oral nonsteroidal anti-inflammatory drug. Conclusion: The posteromedial and posterolateral approaches for PTPF is good for reduction and fixation of PTPF. The approaches have benefits such as clear exposure, convenient placement of internal fixation, less trauma and good clinical outcome. PMID:26885086

  8. Standardized bonding protocol posterior porcelain restorations.

    PubMed

    Schoenbaum, Todd R

    2011-06-01

    Strict adherence to a carefully designed protocol for the cementation of posterior porcelain restorations allows for a reliable and minimally invasive procedure. Though such a thorough protocol for porcelain cementation may initially seem time consuming or over-engineered, it is quickly learned and can be applied in nearly all situations. As with many practices in dentistry, the cementation is but the final step in the creation of a beautiful, minimally invasive, and durable restoration that lies at the end of a long line of procedures. All these procedures must also be completed at equivalent levels of excellence to ensure a successful result (Figures 10 to 12). PMID:21761632

  9. Complications when augmenting the posterior maxilla.

    PubMed

    Fugazzotto, Paul; Melnick, Philip R; Al-Sabbagh, Mohanad

    2015-01-01

    The maxillary posterior edentulous region presents a challenge when planning for restoring missing teeth with a dental implant. The available bone in such cases is often not dense and not adequate for the placement of a properly sized implant because of maxillary sinus pneumatization and alveolar bone loss. Maxillary sinus lift is a predictable procedure to provide adequate bone height for the purpose of implant placement. However, complications are encountered during or after the execution of the sinus lift procedure. In this article, the prevention and management of maxillary sinus complications are discussed. PMID:25434561

  10. Accurate and fast replication on the generation of fractal network traffic using alternative probability models

    NASA Astrophysics Data System (ADS)

    Fernandes, Stenio; Kamienski, Carlos; Sadok, Djamel

    2003-08-01

    Synthetic self-similar traffic in computer networks simulation is of imperative significance for the capturing and reproducing of actual Internet data traffic behavior. A universally used procedure for generating self-similar traffic is achieved by aggregating On/Off sources where the active (On) and idle (Off) periods exhibit heavy tailed distributions. This work analyzes the balance between accuracy and computational efficiency in generating self-similar traffic and presents important results that can be useful to parameterize existing heavy tailed distributions such as Pareto, Weibull and Lognormal in a simulation analysis. Our results were obtained through the simulation of various scenarios and were evaluated by estimating the Hurst (H) parameter, which measures the self-similarity level, using several methods.

  11. Probability Surveys, Conditional Probability, and Ecological Risk Assessment

    EPA Science Inventory

    We show that probability-based environmental resource monitoring programs, such as the U.S. Environmental Protection Agency’s (U.S. EPA) Environmental Monitoring and Assessment Program, and conditional probability analysis can serve as a basis for estimating ecological risk over ...

  12. Probability Surveys, Conditional Probability, and Ecological Risk Assessment

    EPA Science Inventory

    We show that probability-based environmental resource monitoring programs, such as the U.S. Environmental Protection Agencys (U.S. EPA) Environmental Monitoring and Assessment Program, and conditional probability analysis can serve as a basis for estimating ecological risk over ...

  13. OCTAVIA. Pressure Vessel Failure Probabilities

    SciTech Connect

    Vesely, W. E.; Lynn, E. K.; Goldberg, F. F.

    1992-01-13

    OCTAVIA (Operationally Caused Transients And Vessel Integrity Analysis) calculates the probability of pressure vessel failure from operationally-caused pressure transients which can occur in a pressurized water reactor (PWR). For specified vessel and operating environment characteristics the program computes the failure pressure at which the vessel will fail for different-sized flaws existing in the beltline and the probability of vessel failure per reactor year due to the flaw. The probabilities are summed over the various flaw sizes to obtain the total vessel failure probability. Sensitivity studies can be performed to investigate different vessel or operating characteristics in the same computer run.

  14. Accurate Evaluation of Quantum Integrals

    NASA Technical Reports Server (NTRS)

    Galant, D. C.; Goorvitch, D.; Witteborn, Fred C. (Technical Monitor)

    1995-01-01

    Combining an appropriate finite difference method with Richardson's extrapolation results in a simple, highly accurate numerical method for solving a Schrodinger's equation. Important results are that error estimates are provided, and that one can extrapolate expectation values rather than the wavefunctions to obtain highly accurate expectation values. We discuss the eigenvalues, the error growth in repeated Richardson's extrapolation, and show that the expectation values calculated on a crude mesh can be extrapolated to obtain expectation values of high accuracy.

  15. The relationship between species detection probability and local extinction probability

    USGS Publications Warehouse

    Alpizar-Jara, R.; Nichols, J.D.; Hines, J.E.; Sauer, J.R.; Pollock, K.H.; Rosenberry, C.S.

    2004-01-01

    In community-level ecological studies, generally not all species present in sampled areas are detected. Many authors have proposed the use of estimation methods that allow detection probabilities that are <1 and that are heterogeneous among species. These methods can also be used to estimate community-dynamic parameters such as species local extinction probability and turnover rates (Nichols et al. Ecol Appl 8:1213-1225; Conserv Biol 12:1390-1398). Here, we present an ad hoc approach to estimating community-level vital rates in the presence of joint heterogeneity of detection probabilities and vital rates. The method consists of partitioning the number of species into two groups using the detection frequencies and then estimating vital rates (e.g., local extinction probabilities) for each group. Estimators from each group are combined in a weighted estimator of vital rates that accounts for the effect of heterogeneity. Using data from the North American Breeding Bird Survey, we computed such estimates and tested the hypothesis that detection probabilities and local extinction probabilities were negatively related. Our analyses support the hypothesis that species detection probability covaries negatively with local probability of extinction and turnover rates. A simulation study was conducted to assess the performance of vital parameter estimators as well as other estimators relevant to questions about heterogeneity, such as coefficient of variation of detection probabilities and proportion of species in each group. Both the weighted estimator suggested in this paper and the original unweighted estimator for local extinction probability performed fairly well and provided no basis for preferring one to the other.

  16. Traumatic posterior dislocation of hip in children.

    PubMed

    Kutty, S; Thornes, B; Curtin, W A; Gilmore, M F

    2001-02-01

    Traumatic posterior dislocation of the hip joint in children is an uncommon injury. It constitutes a true orthopedic emergency. It makes up over 80% of pediatric hip dislocations. In children, it can occur as a result of minimal trauma, which is attributed to a soft pliable acetabulum and ligamentous laxity. In skeletally mature adolescents, a greater force is required to dislocate the hip joint. Delay in reduction is associated with long-term complications such as avascular necrosis and degenerative arthritis. Avascular necrosis is related to the duration of dislocation. A poorer prognosis is associated with delay in reduction beyond 6 hours, advanced skeletal maturity, or multiple traumas. Prompt reduction minimizes complications. We report two cases of traumatic posterior dislocation of hip in children aged 3 and 14 years. Both were reduced within 6 hours of dislocation, and review at 6 months revealed normal examination and no evidence of any post-traumatic changes. Post-reduction treatment remains without a consensus. This review highlights the clinical presentation, management, and time-sensitive complications of the injury. PMID:11265904

  17. Posterior malleolar fractures of the ankle.

    PubMed

    Bartoníček, J; Rammelt, S; Tuček, M; Naňka, O

    2015-12-01

    Despite an increasing awareness of injuries to PM in ankle fracture-dislocations, there are still many open questions. The mere presence of a posterior fragment leads to significantly poorer outcomes. Adequate diagnosis, classification and treatment require preoperative CT examination, preferably with 3D reconstructions. The indication for surgical treatment is made individually on the basis of comprehensive assessment of the three-dimensional outline of the PM fracture and all associated injuries to the ankle including syndesmotic instability. Anatomic fixation of the avulsed posterior tibiofibular ligament will contribute to syndesmotic stability and restore the integrity of the incisura tibiae thus facilitating anatomic reduction of the distal fibula. A necessary prerequisite is mastering of posterolateral and posteromedial approaches and the technique of direct reduction and internal fixation. Further clinical studies with higher numbers of patients treated by similar methods and evaluation of pre- and postoperative CT scans will be necessary to determine reliable prognostic factors associated with certain types of PM fractures and associated injuries to the ankle. PMID:26253884

  18. Management of an Uncomplicated Posterior Elbow Dislocation

    PubMed Central

    Blackard, Douglas; Sampson, Jo-Ann

    1997-01-01

    Objective: To present a case of an uncomplicated posterior elbow dislocation in a US World Cup athlete and discuss her rehabilitation. Background: Traditional protocol for management of this injury has been splint immobilization for several weeks, but research suggests a shortened duration of immobilization and early active motion. Differential Diagnosis: Elbow dislocation with possible fracture. Treatment: The dislocation was reduced and a compression bandage and sling were applied. The sports medicine staff and athlete determined that rehabilitation would involve limited immobilization with a posterior splint. Also, active range-of- motion exercises were to be incorporated early in the range-of- motion program to decrease pain at the articulation. Uniqueness: The athlete was not immobilized and her aggressive five-phase rehabilitation program progressed according to decrease in inflammation and increase in range of motion and strength. Conclusions: Shortened immobilization and return to World Championship competition 6 weeks postinjury had no longterm adverse effects on the athlete. ImagesFig 1.Fig 2.Fig 3.Fig 4.Fig. 5. PMID:16558436

  19. Prehension Movements in a Patient (AC) with Posterior Parietal Cortex Damage and Posterior Callosal Section

    ERIC Educational Resources Information Center

    Frak, Victor; Paulignan, Yves; Jeannerod, Marc; Michel, Francois; Cohen, Henri

    2006-01-01

    Prehension movements of the right hand were recorded in a right-handed man (AC), with an injury to the left posterior parietal cortex (PPC) and with a section of the left half of the splenium. The kinematic analysis of AC's grasping movements in direct and perturbed conditions was compared to that of five control subjects. A novel effect in…

  20. Clinical simulation using context-sensitive temporal probability models.

    PubMed Central

    Haddawy, P.; Helwig, J. W.; Ngo, L.; Krieger, R. A.

    1995-01-01

    We present a language for representing context-sensitive temporal probabilistic knowledge. Context constraints allow inference to be focused on only the relevant portions of the probabilistic knowledge. We provide a declarative semantics for our language and an implemented algorithm (BNG) that generates Bayesian networks to compute the posterior probabilities of queries. We illustrate the use of the BNG system by applying it to the problem of modeling the effects of medications and other interventions on the condition of a patient in cardiac arrest. PMID:8563268

  1. Distortions of the posterior surface in optical coherence tomography images of the isolated crystalline lens: effect of the lens index gradient

    PubMed Central

    Borja, David; Siedlecki, Damian; de Castro, Alberto; Uhlhorn, Stephen; Ortiz, Sergio; Arrieta, Esdras; Parel, Jean-Marie; Marcos, Susana; Manns, Fabrice

    2010-01-01

    We quantify the posterior surface distortions in optical coherence tomography (OCT) images of isolated crystalline lenses. The posterior radius of curvature and asphericity obtained from OCT images acquired with the beam incident first on the anterior, and then the posterior, surface were compared. The results were compared with predictions of a ray-tracing model which includes the index gradient. The results show that the error in the radius of curvature is within the measurement reproducibility and that it can be corrected by assuming a uniform refractive index. However, accurate asphericity values require a correction algorithm that takes into account the gradient. PMID:21258553

  2. Decision analysis with approximate probabilities

    NASA Technical Reports Server (NTRS)

    Whalen, Thomas

    1992-01-01

    This paper concerns decisions under uncertainty in which the probabilities of the states of nature are only approximately known. Decision problems involving three states of nature are studied. This is due to the fact that some key issues do not arise in two-state problems, while probability spaces with more than three states of nature are essentially impossible to graph. The primary focus is on two levels of probabilistic information. In one level, the three probabilities are separately rounded to the nearest tenth. This can lead to sets of rounded probabilities which add up to 0.9, 1.0, or 1.1. In the other level, probabilities are rounded to the nearest tenth in such a way that the rounded probabilities are forced to sum to 1.0. For comparison, six additional levels of probabilistic information, previously analyzed, were also included in the present analysis. A simulation experiment compared four criteria for decisionmaking using linearly constrained probabilities (Maximin, Midpoint, Standard Laplace, and Extended Laplace) under the eight different levels of information about probability. The Extended Laplace criterion, which uses a second order maximum entropy principle, performed best overall.

  3. Capture probabilities for secondary resonances

    NASA Technical Reports Server (NTRS)

    Malhotra, Renu

    1990-01-01

    A perturbed pendulum model is used to analyze secondary resonances, and it is shown that a self-similarity between secondary and primary resonances exists. Henrard's (1982) theory is used to obtain formulas for the capture probability into secondary resonances. The tidal evolution of Miranda and Umbriel is considered as an example, and significant probabilities of capture into secondary resonances are found.

  4. Probability of sea level rise

    SciTech Connect

    Titus, J.G.; Narayanan, V.K.

    1995-10-01

    The report develops probability-based projections that can be added to local tide-gage trends to estimate future sea level at particular locations. It uses the same models employed by previous assessments of sea level rise. The key coefficients in those models are based on subjective probability distributions supplied by a cross-section of climatologists, oceanographers, and glaciologists.

  5. The Probabilities of Conditionals Revisited

    ERIC Educational Resources Information Center

    Douven, Igor; Verbrugge, Sara

    2013-01-01

    According to what is now commonly referred to as "the Equation" in the literature on indicative conditionals, the probability of any indicative conditional equals the probability of its consequent of the conditional given the antecedent of the conditional. Philosophers widely agree in their assessment that the triviality arguments of…

  6. Training Teachers to Teach Probability

    ERIC Educational Resources Information Center

    Batanero, Carmen; Godino, Juan D.; Roa, Rafael

    2004-01-01

    In this paper we analyze the reasons why the teaching of probability is difficult for mathematics teachers, describe the contents needed in the didactical preparation of teachers to teach probability and analyze some examples of activities to carry out this training. These activities take into account the experience at the University of Granada,…

  7. Linear positivity and virtual probability

    NASA Astrophysics Data System (ADS)

    Hartle, James B.

    2004-08-01

    We investigate the quantum theory of closed systems based on the linear positivity decoherence condition of Goldstein and Page. The objective of any quantum theory of a closed system, most generally the universe, is the prediction of probabilities for the individual members of sets of alternative coarse-grained histories of the system. Quantum interference between members of a set of alternative histories is an obstacle to assigning probabilities that are consistent with the rules of probability theory. A quantum theory of closed systems therefore requires two elements: (1) a condition specifying which sets of histories may be assigned probabilities and (2) a rule for those probabilities. The linear positivity condition of Goldstein and Page is the weakest of the general conditions proposed so far. Its general properties relating to exact probability sum rules, time neutrality, and conservation laws are explored. Its inconsistency with the usual notion of independent subsystems in quantum mechanics is reviewed. Its relation to the stronger condition of medium decoherence necessary for classicality is discussed. The linear positivity of histories in a number of simple model systems is investigated with the aim of exhibiting linearly positive sets of histories that are not decoherent. The utility of extending the notion of probability to include values outside the range of 0-1 is described. Alternatives with such virtual probabilities cannot be measured or recorded, but can be used in the intermediate steps of calculations of real probabilities. Extended probabilities give a simple and general way of formulating quantum theory. The various decoherence conditions are compared in terms of their utility for characterizing classicality and the role they might play in further generalizations of quantum mechanics.

  8. MARKOV CHAIN MONTE CARLO POSTERIOR SAMPLING WITH THE HAMILTONIAN METHOD

    SciTech Connect

    K. HANSON

    2001-02-01

    The Markov Chain Monte Carlo technique provides a means for drawing random samples from a target probability density function (pdf). MCMC allows one to assess the uncertainties in a Bayesian analysis described by a numerically calculated posterior distribution. This paper describes the Hamiltonian MCMC technique in which a momentum variable is introduced for each parameter of the target pdf. In analogy to a physical system, a Hamiltonian H is defined as a kinetic energy involving the momenta plus a potential energy {var_phi}, where {var_phi} is minus the logarithm of the target pdf. Hamiltonian dynamics allows one to move along trajectories of constant H, taking large jumps in the parameter space with relatively few evaluations of {var_phi} and its gradient. The Hamiltonian algorithm alternates between picking a new momentum vector and following such trajectories. The efficiency of the Hamiltonian method for multidimensional isotropic Gaussian pdfs is shown to remain constant at around 7% for up to several hundred dimensions. The Hamiltonian method handles correlations among the variables much better than the standard Metropolis algorithm. A new test, based on the gradient of {var_phi}, is proposed to measure the convergence of the MCMC sequence.

  9. Posterior cruciate ligament rehabilitation: how slow should we go?

    PubMed

    Fanelli, Gregory C

    2008-02-01

    Outcomes after posterior cruciate ligament (PCL) reconstructive surgery have historically been inferior to outcomes after reconstruction of the anterior cruciate ligament (ACL). As such, some surgeons may be reluctant to recommend reconstruction of the PCL. However, recent technologic advances have substantially improved PCL reconstructive surgical outcomes. These advances include better understanding of PCL diagnosis and surgical indications; recognition of the need for repair or reconstruction of associated injuries, especially injuries to the posterolateral and posteromedial corners of the knee; PCL-specific surgical instruments including mechanical tensioning devices to restore anatomic tibial step-off; improved graft fixation techniques including primary and backup methods of fixation; use of strong graft material including advances in the procurement, processing, and usage of allograft tissue; improved surgical techniques; and advances in the understanding of knee ligament structure and biomechanics, resulting in more accurate surgical tunnel placement, achieving anatomic graft insertion sites while minimizing graft bending. Today, PCL reconstructive surgery often results in excellent function with a return to the patient's preinjury level of activity. In contrast to accelerated rehabilitation after ACL reconstructive surgery, slow and deliberate postoperative rehabilitation is recommended to allow early healing to occur after PCL reconstructive surgery. PMID:18251084

  10. Posterior cortical atrophy: visuomotor deficits in reaching and grasping

    PubMed Central

    Meek, Benjamin P.; Shelton, Paul; Marotta, Jonathan J.

    2013-01-01

    Posterior Cortical Atrophy (PCA) is a rare clinical syndrome characterized by the predominance of higher-order visual disturbances such as optic ataxia, a characteristic of Balint's syndrome. Deficits result from progressive neurodegeneration of occipito-temporal and occipito-parietal cortices. The current study sought to explore the visuomotor functioning of four individuals with PCA by testing their ability to reach out and grasp real objects under various viewing conditions. Experiment 1 had participants reach out and grasp simple, rectangular blocks under visually- and memory-guided conditions. Experiment 2 explored participants' abilities to accurately reach for objects located in their visual periphery. This investigation revealed that PCA patients demonstrate many of the same deficits that have been previously reported in other individuals with optic ataxia, such as “magnetic misreaching”—a pathological reaching bias toward the point of visual fixation when grasping peripheral targets. Unlike many other individuals with optic ataxia, however, the patients in the current study also show symptoms indicative of damage to the more perceptual stream of visual processing, including abolished grip scaling during memory-guided grasping and deficits in face and object identification. These investigations are the first to perform a quantitative analysis of the visuomotor deficits exhibited by patients with PCA. Critically, this study helps characterize common symptoms of PCA, a vital first step for generating effective diagnostic criteria and therapeutic strategies for this understudied neurodegenerative disorder. PMID:23801956

  11. Posterior adhesive composite resin: a historic review.

    PubMed

    Fusayama, T

    1990-11-01

    Since development of the BIS-GMA composite resin, there have been many innovations to improve the physical properties for posterior use. Subsequent development of a caries detector and chemically adhesive composite resin has further revolutionally raised the value of composite resin restoration, replacing the traditional restorative system of mechanical approach by the new system of biological approach. In this system only the infected irreversibly deteriorated insensitive tissue, stainable with the caries detector, is removed painlessly. The cavity is immediately filled with the composite resin with no further tissue reduction for retention or resistance form or extension for prevention. Both enamel and dentin walls are etched by a single etchant without lining. The chemical adhesion to the cavity margin and wall minimizes the marginal failure in size and prevalence and prevents secondary caries penetration along the wall. The chemically adhesive composite resin is thus a useful restorative material much kinder to teeth than amalgam. PMID:2090811

  12. Ectomesenchymal chondromyxoid tumour of the posterior tongue.

    PubMed

    Cardin, Marie-Josée; Fiset, Pierre Olivier; Zeitouni, Anthony G; Caglar, Derin

    2014-01-01

    Ectomesenchymal chondromyxoid tumor (ECMT) is a rare benign neoplasm arising in the tongue. With only 45 cases reported in the literature, there are several unique features defining this lesion. Firstly, almost all patients present with an asymptomatic slow growing mass on the anterior dorsum of the tongue. At the microscopic level, it is recognizable as a well-circumscribed unencapsulated proliferation of uniform round to fusiform cells embedded in a chondromyxoid matrix. Lastly, the immunohistochemistry profile is characterised by positivity for glial fibrillary acidic protein and frequent positivity for S-100 and cytokeratins. We report a case of a mass located on the posterior dorsum of the tongue and meeting the aforementioned morphological and immunohistochemical criteria of ECMT. PMID:24288100

  13. Iodine-125 radiation of posterior uveal melanoma

    SciTech Connect

    Packer, S.

    1987-12-01

    Twenty-eight cases of posterior choroidal melanoma were treated with iodine-125 in gold eye plaques. Eleven cases were located within 3.0 mm of the optic nerve (group A), nine were within 3.0 mm of the fovea (group B), and eight were within 3.0 mm of the optic nerve and fovea (group C). The mean follow-up of group A was 46.3 months; group B, 25.5 months; and group C, 42.7 months. Complications included macular edema, cataract and tumor growth. Visual acuity remained within two lines of that tested preoperatively for 4 of 11 patients in group A, 4 of 9 in group B, and 5 of 8 in group C. These results with iodine-125 suggest it as an appropriate treatment for patients with choroidal melanoma located near optic nerve and/or macula.

  14. [Posterior cortical atrophy with progressive visual agnosia].

    PubMed

    Zarranz, J J; Lasa, A; Fernández, M; Lezcano, E; Pérez Bas, M; Varona, L; Ruiz, J; Beristain, X

    1995-03-01

    Interest in progressive focal cerebral syndromes associated with classical degenerative diseases has increased in recent years. Descriptions of posterior cortical atrophy with progressive visual agnosia are relatively rare. We present 5 patients (2 women) ranging in age between 57 and 72 years old. In all cases symptoms began and progressed with no known etiology. All cases were sporadic. The main clinical signs are difficulty in recognizing objects, colors, persons or places; topographical disorientation and visual memory alterations; alexia, simultagnosia, loss of ocular fixing and optic ataxia. Some patients presented other disturbances of praxis or memory and 2 progressed to global dementia. Language function was preserved and behavioral disturbances did not develop. The amplitude of the P100 visual evoked potential was low but latency was normal in 4 patients and prolonged in 1. Brain images showed atrophy and hypoperfusion in the parieto-occipital area. The neuropathology status of these patients is unknown. PMID:7756009

  15. Arthroscopic Reverse Remplissage for Posterior Instability

    PubMed Central

    Lavender, Chad D.; Hanzlik, Shane R.; Pearson, Sara E.; Caldwell, Paul E.

    2016-01-01

    Posterior shoulder dislocation is an unusual injury often associated with electrical shock or seizure. As with anterior instability, patients frequently present with an impaction injury to the anterior aspect of the humeral head known as a “reverse Hill-Sachs lesion.” The treatment of this bony defect is controversial, and multiple surgical procedures to fill the defect in an effort to decrease recurrence have been described. Most of the reports have focused on an open approach using variations of lesser tuberosity and subscapularis transfers, bone allograft, and even arthroplasty to assist with persistent instability. We advocate an arthroscopic technique that involves a suture anchor–based distal tenodesis of the subscapularis tendon or a reverse remplissage procedure.

  16. Potential acuity meter for predicting visual acuity after Nd:YAG posterior capsulotomy

    SciTech Connect

    Smiddy, W.E.; Radulovic, D.; Yeo, J.H.; Stark, W.J.; Maumenee, A.E.

    1986-03-01

    We studied 30 patients with opacifications of the posterior capsule to determine if the potential acuity meter (PAM) could accurately predict final visual outcome after Nd:YAG discussion. The final visual acuity was within one line of the PAM prediction in 22 of 30 patients (73%), better by two or more lines in seven patients (23%), and worse in one patient (4%) by two lines. Although in thicker capsules the final acuity was occasionally better than the PAM prediction, the rates of false negative and false positive predictions were very low. Mild cystoid macular edema (3 patients), age-related macular degeneration (3 patients), intraocular lens status, and level of initial acuity did not diminish PAM accuracy. The PAM effectively predicts final visual acuity after YAG posterior capsulotomy, when used in a patient, unhurried manner.

  17. Effect of posterior decompression extent on biomechanical parameters of the spinal cord in cervical ossification of the posterior longitudinal ligament.

    PubMed

    Khuyagbaatar, Batbayar; Kim, Kyungsoo; Park, Won Man; Kim, Yoon Hyuk

    2016-06-01

    Ossification of the posterior longitudinal ligament is a common cause of the cervical myelopathy due to compression of the spinal cord. Patients with ossification of the posterior longitudinal ligament usually require the decompression surgery, and there is a need to better understand the optimal surgical extent with which sufficient decompression without excessive posterior shifting can be achieved. However, few quantitative studies have clarified this optimal extent for decompression of cervical ossification of the posterior longitudinal ligament. We used finite element modeling of the cervical spine and spinal cord to investigate the effect of posterior decompression extent for continuous-type cervical ossification of the posterior longitudinal ligament on changes in stress, strain, and posterior shifting that occur with three different surgical methods (laminectomy, laminoplasty, and hemilaminectomy). As posterior decompression extended, stress and strain in the spinal cord decreased and posterior shifting of the cord increased. The location of the decompression extent also influenced shifting. Laminectomy and laminoplasty were very similar in terms of decompression results, and both were superior to hemilaminectomy in all parameters tested. Decompression to the extents of C3-C6 and C3-C7 of laminectomy and laminoplasty could be considered sufficient with respect to decompression itself. Our findings provide fundamental information regarding the treatment of cervical ossification of the posterior longitudinal ligament and can be applied to patient-specific surgical planning. PMID:26951839

  18. Experimental models for posterior capsule opacification research.

    PubMed

    Wormstone, Ian Michael; Eldred, Julie Ann

    2016-01-01

    Millions of people worldwide are blinded due to cataract formation. At present the only means of treating a cataract is through surgical intervention. A modern cataract operation involves the creation of an opening in the anterior lens capsule to allow access to the fibre cells, which are then removed. This leaves in place a capsular bag that comprises the remaining anterior capsule and the entire posterior capsule. In most cases, an intraocular lens is implanted into the capsular bag during surgery. This procedure initially generates good visual restoration, but unfortunately, residual lens epithelial cells undergo a wound-healing response invoked by surgery, which in time commonly results in a secondary loss of vision. This condition is known as posterior capsule opacification (PCO) and exhibits classical features of fibrosis, including hyperproliferation, migration, matrix deposition, matrix contraction and transdifferentiation into myofibroblasts. These changes alone can cause visual deterioration, but in a significant number of cases, fibre differentiation is also observed, which gives rise to Soemmering's ring and Elschnig's pearl formation. Elucidating the regulatory factors that govern these events is fundamental in the drive to develop future strategies to prevent or delay visual deterioration resulting from PCO. A range of experimental platforms are available for the study of PCO that range from in vivo animal models to in vitro human cell and tissue culture models. In the current review, we will highlight some of the experimental models used in PCO research and provide examples of key findings that have resulted from these approaches. PMID:25939555

  19. Evaluation and management of posterior ankle pain in dancers.

    PubMed

    Luk, Pamela; Thordarson, David; Charlton, Timothy

    2013-01-01

    Posterior ankle pain is a common complaint in dancers. There are multiple structures in the posterior ankle that have the potential to be the source of pain. The objective of this article is to review several of the most common causes of posterior ankle pain: peroneal tendon subluxation, posterior impingement syndrome secondary to a painful os trigonum, posterior talus osteochondritis dissecans, flexor hallucis longus tendinopathy, and posterior tibial tendinopathy. For dancers, we offer typical clinical presentations of these disorders to increase awareness and provide guidance regarding when to seek professional medical attention. For medical personnel who are responsible for optimizing dancers' health and training, we include a discussion of pertinent physical exam findings, diagnostic imaging options, non-operative and operative management, as well as surgical suggestions and postoperative rehabilitation guidelines. PMID:23759482

  20. Definition of the Neutrosophic Probability

    NASA Astrophysics Data System (ADS)

    Smarandache, Florentin

    2014-03-01

    Neutrosophic probability (or likelihood) [1995] is a particular case of the neutrosophic measure. It is an estimation of an event (different from indeterminacy) to occur, together with an estimation that some indeterminacy may occur, and the estimation that the event does not occur. The classical probability deals with fair dice, coins, roulettes, spinners, decks of cards, random works, while neutrosophic probability deals with unfair, imperfect such objects and processes. For example, if we toss a regular die on an irregular surface which has cracks, then it is possible to get the die stuck on one of its edges or vertices in a crack (indeterminate outcome). The sample space is in this case: {1, 2, 3, 4, 5, 6, indeterminacy}. So, the probability of getting, for example 1, is less than 1/6. Since there are seven outcomes. The neutrosophic probability is a generalization of the classical probability because, when the chance of determinacy of a stochastic process is zero, these two probabilities coincide. The Neutrosophic Probability that of an event A occurs is NP (A) = (ch (A) , ch (indetA) , ch (A ̲)) = (T , I , F) , where T , I , F are subsets of [0,1], and T is the chance that A occurs, denoted ch(A); I is the indeterminate chance related to A, ch(indetermA) ; and F is the chance that A does not occur, ch (A ̲) . So, NP is a generalization of the Imprecise Probability as well. If T, I, and F are crisp numbers then: - 0 <= T + I + F <=3+ . We used the same notations (T,I,F) as in neutrosophic logic and set.

  1. Failure probability under parameter uncertainty.

    PubMed

    Gerrard, R; Tsanakas, A

    2011-05-01

    In many problems of risk analysis, failure is equivalent to the event of a random risk factor exceeding a given threshold. Failure probabilities can be controlled if a decisionmaker is able to set the threshold at an appropriate level. This abstract situation applies, for example, to environmental risks with infrastructure controls; to supply chain risks with inventory controls; and to insurance solvency risks with capital controls. However, uncertainty around the distribution of the risk factor implies that parameter error will be present and the measures taken to control failure probabilities may not be effective. We show that parameter uncertainty increases the probability (understood as expected frequency) of failures. For a large class of loss distributions, arising from increasing transformations of location-scale families (including the log-normal, Weibull, and Pareto distributions), the article shows that failure probabilities can be exactly calculated, as they are independent of the true (but unknown) parameters. Hence it is possible to obtain an explicit measure of the effect of parameter uncertainty on failure probability. Failure probability can be controlled in two different ways: (1) by reducing the nominal required failure probability, depending on the size of the available data set, and (2) by modifying of the distribution itself that is used to calculate the risk control. Approach (1) corresponds to a frequentist/regulatory view of probability, while approach (2) is consistent with a Bayesian/personalistic view. We furthermore show that the two approaches are consistent in achieving the required failure probability. Finally, we briefly discuss the effects of data pooling and its systemic risk implications. PMID:21175720

  2. Posterior Circulation Stroke: Animal Models and Mechanism of Disease

    PubMed Central

    Lekic, Tim; Ani, Chizobam

    2012-01-01

    Posterior circulation stroke refers to the vascular occlusion or bleeding, arising from the vertebrobasilar vasculature of the brain. Clinical studies show that individuals who experience posterior circulation stroke will develop significant brain injury, neurologic dysfunction, or death. Yet the therapeutic needs of this patient subpopulation remain largely unknown. Thus understanding the causative factors and the pathogenesis of brain damage is important, if posterior circulation stroke is to be prevented or treated. Appropriate animal models are necessary to achieve this understanding. This paper critically integrates the neurovascular and pathophysiological features gleaned from posterior circulation stroke animal models into clinical correlations. PMID:22665986

  3. Diagnostics for insufficiencies of posterior calculations in Bayesian signal inference.

    PubMed

    Dorn, Sebastian; Oppermann, Niels; Ensslin, Torsten A

    2013-11-01

    We present an error-diagnostic validation method for posterior distributions in Bayesian signal inference, an advancement of a previous work. It transfers deviations from the correct posterior into characteristic deviations from a uniform distribution of a quantity constructed for this purpose. We show that this method is able to reveal and discriminate several kinds of numerical and approximation errors, as well as their impact on the posterior distribution. For this we present four typical analytical examples of posteriors with incorrect variance, skewness, position of the maximum, or normalization. We show further how this test can be applied to multidimensional signals. PMID:24329375

  4. The Probabilities of Unique Events

    PubMed Central

    Khemlani, Sangeet S.; Lotstein, Max; Johnson-Laird, Phil

    2012-01-01

    Many theorists argue that the probabilities of unique events, even real possibilities such as President Obama's re-election, are meaningless. As a consequence, psychologists have seldom investigated them. We propose a new theory (implemented in a computer program) in which such estimates depend on an intuitive non-numerical system capable only of simple procedures, and a deliberative system that maps intuitions into numbers. The theory predicts that estimates of the probabilities of conjunctions should often tend to split the difference between the probabilities of the two conjuncts. We report two experiments showing that individuals commit such violations of the probability calculus, and corroborating other predictions of the theory, e.g., individuals err in the same way even when they make non-numerical verbal estimates, such as that an event is highly improbable. PMID:23056224

  5. Joint probabilities and quantum cognition

    NASA Astrophysics Data System (ADS)

    de Barros, J. Acacio

    2012-12-01

    In this paper we discuss the existence of joint probability distributions for quantumlike response computations in the brain. We do so by focusing on a contextual neural-oscillator model shown to reproduce the main features of behavioral stimulus-response theory. We then exhibit a simple example of contextual random variables not having a joint probability distribution, and describe how such variables can be obtained from neural oscillators, but not from a quantum observable algebra.

  6. Evaluation of microbial release probabilities

    NASA Technical Reports Server (NTRS)

    1972-01-01

    Work undertaken to improve the estimation of the probability of release of microorganisms from unmanned Martian landing spacecraft is summarized. An analytical model is described for the development of numerical values for release parameters and release mechanisms applicable to flight missions are defined. Laboratory test data are used to evolve parameter values for use by flight projects in estimating numerical values for release probabilities. The analysis treats microbial burden located on spacecraft surfaces, between mated surfaces, and encapsulated within materials.

  7. Joint probabilities and quantum cognition

    SciTech Connect

    Acacio de Barros, J.

    2012-12-18

    In this paper we discuss the existence of joint probability distributions for quantumlike response computations in the brain. We do so by focusing on a contextual neural-oscillator model shown to reproduce the main features of behavioral stimulus-response theory. We then exhibit a simple example of contextual random variables not having a joint probability distribution, and describe how such variables can be obtained from neural oscillators, but not from a quantum observable algebra.

  8. Posterior tibial subluxation and short-term arthritis resulting from failed posterior cruciate ligament reconstruction.

    PubMed

    Mavrodontidis, Alexandros N; Papadonikolakis, Anastasios; Moebius, Ulf G; Gelalis, Ioannis; Motsis, Efstathios; Soucacos, Panayotis N

    2003-01-01

    Posterior tibial subluxations because of combined or isolated posterior cruciate ligament (PCL) injuries require detailed evaluation. PCL reconstructions are difficult procedures because of the low rate of such injuries and the complex anatomy of the ligament. We report on 2 cases of failed PCL reconstruction because of malpositioned femoral tunnels. These 2 cases support the existing biomechanical evidence that the correct placement of the tunnels, especially in the femur, is a major factor in defining the outcome. It seems that the drilling of the tunnels, especially in the femur, during PCL reconstruction must be performed with accuracy and always be evaluated in cases of graft failure. In addition, failed PCL reconstructions are usually accompanied by a short-term excessive arthritis that results in poor functional outcome. PMID:12724667

  9. Transition Probabilities of Gd I

    NASA Astrophysics Data System (ADS)

    Bilty, Katherine; Lawler, J. E.; Den Hartog, E. A.

    2011-01-01

    Rare earth transition probabilities are needed within the astrophysics community to determine rare earth abundances in stellar photospheres. The current work is part an on-going study of rare earth element neutrals. Transition probabilities are determined by combining radiative lifetimes measured using time-resolved laser-induced fluorescence on a slow atom beam with branching fractions measured from high resolution Fourier transform spectra. Neutral rare earth transition probabilities will be helpful in improving abundances in cool stars in which a significant fraction of rare earths are neutral. Transition probabilities are also needed for research and development in the lighting industry. Rare earths have rich spectra containing 100's to 1000's of transitions throughout the visible and near UV. This makes rare earths valuable additives in Metal Halide - High Intensity Discharge (MH-HID) lamps, giving them a pleasing white light with good color rendering. This poster presents the work done on neutral gadolinium. We will report radiative lifetimes for 135 levels and transition probabilities for upwards of 1500 lines of Gd I. The lifetimes are reported to ±5% and the transition probabilities range from 5% for strong lines to 25% for weak lines. This work is supported by the National Science Foundation under grant CTS 0613277 and the National Science Foundation's REU program through NSF Award AST-1004881.

  10. Deep Posterior Compartment Strength and Foot Kinematics in Subjects With Stage II Posterior Tibial Tendon Dysfunction

    PubMed Central

    Neville, Christopher; Flemister, Adolph S.; Houck, Jeff R.

    2010-01-01

    Background Tibialis posterior muscle weakness has been documented in subjects with Stage II posterior tibial tendon dysfunction (PTTD) but the effect of weakness on foot structure remains unclear. The association between strength and flatfoot kinematics may guide treatment such as the use of strengthening programs targeting the tibialis posterior muscle. Materials and Methods Thirty Stage II PTTD subjects (age; 58.1 ± 10.5 years, BMI 30.6 ± 5.4) and 15 matched controls (age; 56.5 ± 7.7 years, BMI 30.6 ± 3.6) volunteered for this study. Deep Posterior Compartment strength was measured from both legs of each subject and the strength ratio was used to compare each subject’s involved side to their uninvolved side. A 20% deficit was defined, a priori, to define two groups of subjects with PTTD. The strength ratio for each group averaged; 1.06 ± 0.1 (range 0.87 to 1.36) for controls, 1.06 ± 0.1 (range, 0.89 to 1.25), for the PTTD strong group, and 0.64 ± 0.2 (range 0.42 to 0.76) for the PTTD weak group. Across four phases of stance, kinematic measures of flatfoot were compared between the three groups using a two-way mixed effect ANOVA model repeated for each kinematic variable. Results Subjects with PTTD regardless of group demonstrated significantly greater hindfoot eversion compared to controls. Subjects with PTTD who were weak demonstrated greater hindfoot eversion compared to subjects with PTTD who were strong. For forefoot abduction and MLA angles the differences between groups depended on the phase of stance with significant differences between each group observed at the pre-swing phase of stance. Conclusion Strength was associated with the degree of flatfoot deformity observed during walking, however, flatfoot deformity may also occur without strength deficits. PMID:20371019

  11. Application of sequential probability ratio test to uranium enrichment verification

    NASA Astrophysics Data System (ADS)

    Pratt, J. C.; Close, D. A.

    1987-08-01

    The sequential probability ratio test is a statistical process capable of quickly and accurately verifying the uranium enrichment in the header pipes of uranium centrifuge enrichment facilities. The test minimizes the time required for a measurement, making a complete verification possible in 15-30 min.

  12. Joint probability distributions for projection probabilities of random orthonormal states

    NASA Astrophysics Data System (ADS)

    Alonso, L.; Gorin, T.

    2016-04-01

    The quantum chaos conjecture applied to a finite dimensional quantum system implies that such a system has eigenstates that show similar statistical properties as the column vectors of random orthogonal or unitary matrices. Here, we consider the different probabilities for obtaining a specific outcome in a projective measurement, provided the system is in one of its eigenstates. We then give analytic expressions for the joint probability density for these probabilities, with respect to the ensemble of random matrices. In the case of the unitary group, our results can be applied, also, to the phenomenon of universal conductance fluctuations, where the same mathematical quantities describe partial conductances in a two-terminal mesoscopic scattering problem with a finite number of modes in each terminal.

  13. Paratrooper's Ankle Fracture: Posterior Malleolar Fracture

    PubMed Central

    Young, Ki Won; Cho, Jae Ho; Kim, Hyung Seuk; Cho, Hun Ki; Lee, Kyung Tai

    2015-01-01

    Background We assessed the frequency and types of ankle fractures that frequently occur during parachute landings of special operation unit personnel and analyzed the causes. Methods Fifty-six members of the special force brigade of the military who had sustained ankle fractures during parachute landings between January 2005 and April 2010 were retrospectively analyzed. The injury sites and fracture sites were identified and the fracture types were categorized by the Lauge-Hansen and Weber classifications. Follow-up surveys were performed with respect to the American Orthopedic Foot and Ankle Society ankle-hindfoot score, patient satisfaction, and return to preinjury activity. Results The patients were all males with a mean age of 23.6 years. There were 28 right and 28 left ankle fractures. Twenty-two patients had simple fractures and 34 patients had comminuted fractures. The average number of injury and fractures sites per person was 2.07 (116 injuries including a syndesmosis injury and a deltoid injury) and 1.75 (98 fracture sites), respectively. Twenty-three cases (41.07%) were accompanied by posterior malleolar fractures. Fifty-five patients underwent surgery; of these, 30 had plate internal fixations. Weber type A, B, and C fractures were found in 4, 38, and 14 cases, respectively. Based on the Lauge-Hansen classification, supination-external rotation injuries were found in 20 cases, supination-adduction injuries in 22 cases, pronation-external rotation injuries in 11 cases, tibiofibular fractures in 2 cases, and simple medial malleolar fractures in 2 cases. The mean follow-up period was 23.8 months, and the average follow-up American Orthopedic Foot and Ankle Society ankle-hindfoot score was 85.42. Forty-five patients (80.36%) reported excellent or good satisfaction with the outcome. Conclusions Posterior malleolar fractures occurred in 41.07% of ankle fractures sustained in parachute landings. Because most of the ankle fractures in parachute injuries were compound fractures, most cases had to undergo surgical repairs. PMID:25729514

  14. The I/LWEQ Domain in RapGAP3 Required for Posterior Localization in Migrating Cells

    PubMed Central

    Lee, Mi-Rae; Kim, Hyeseon; Jeon, Taeck J.

    2014-01-01

    Cell migration requires a defined cell polarity which is formed by diverse cytoskeletal components differentially localized to the poles of cells to extracellular signals. Rap-GAP3 transiently and rapidly translocates to the cell cortex in response to chemoattractant stimulation and localizes to the leading edge of migrating cells. Here, we examined localization of truncated RapGAP3 proteins and found that the I/LWEQ domain in the central region of RapGAP3 was sufficient for posterior localization in migrating cells, as opposed to leading-edge localization of full-length Rap-GAP3. All truncated proteins accumulated at the leading edge of migrating cells exhibited clear translocation to the cell cortex in response to stimulation, whereas proteins localized to the posterior in migrating cells displayed no translocation to the cortex. The I/LWEQ domain appears to passively accumulate at the posterior region in migrating cells due to exclusion from the extended front region in response to chemoattractant stimulation rather than actively being localized to the back of cells. Our results suggest that posterior localization of the I/LWEQ domain of RapGAP3 is likely related to F-actin, which has probably different properties compared to newly formed F-actin at the leading edge of migrating cells, at the lateral and posterior regions of the cell. PMID:24608804

  15. Automatic quantification of posterior capsule opacification

    NASA Astrophysics Data System (ADS)

    Barman, Sarah A.; Uyyanonvara, Bunyarit; Boyce, James F.; Sanguinetti, Giorgia; Hollick, Emma J.; Meacock, William R.; Spalton, David J.; Paplinski, Andrew P.

    2000-06-01

    After Cataract surgery where a plastic implant lens is implanted into the eye to replace the natural lens, many patients suffer from cell growth across a membrane situated at the back of the lens which degrades their vision. The cell growth is known as Posterior Capsule Opacification (or PCO). It is important to be able to quantify PCO so that the effect of different implant lens types and surgical techniques may be evaluated. Initial results obtained using a neural network to detect PCO from implant lenses are compared to an established but less automated method of detection, which segments the images using texture segmentation in conjunction with co- occurrence matrices. Tests show that the established method performs well in clinical validation and repeatability trials. The requirement to use a neural network to analyze the implant lens images evolved from the analysis of over 1000 images using the established co-occurrence matrix segmentation method. The work shows that a method based on neural networks is a promising tool to automate the procedure of calculating PCO.

  16. Logopenic syndrome in posterior cortical atrophy.

    PubMed

    Magnin, Eloi; Sylvestre, Geraldine; Lenoir, Flora; Dariel, Elfried; Bonnet, Louise; Chopard, Gilles; Tio, Gregory; Hidalgo, Julie; Ferreira, Sabrina; Mertz, Catherine; Binetruy, Mikael; Chamard, Ludivine; Haffen, Sophie; Ryff, Ilham; Laurent, Eric; Moulin, Thierry; Vandel, Pierre; Rumbach, Lucien

    2013-02-01

    Few language disorders have been reported in posterior cortical atrophy (PCA). Furthermore, no study has focused on screening for them and described these language deficits. The goal of this work was to describe linguistic examination of PCA patients and the impact of language disorders on neuropsychological performances compared to patients with other neurodegenerative syndromes and control groups. Linguistic examination of 9 PCA patients was carried out. The neuropsychological performance of the PCA group (16 patients) in the RAPID battery tests was compared with performances of patients with a logopenic variant of primary progressive aphasia (LPPA), patients with Alzheimer's disease and patients with amnestic mild cognitive impairment, as well as the control group. A "logopenic syndrome" with anomia, fluency impairment, and length-dependent deficit was found in 8/9 PCA patients. A comparison with other neurodegenerative syndromes showed that not only visual disorders but also language and verbal short-term memory disorders, such as those found in LPPA, can explain neuropsychological performances. A "logopenic syndrome" is frequently found in PCA and may be associated with poor performance on other verbally mediated neuropsychological tasks (e.g., verbal memory). Specific logopedic rehabilitation should be offered to these patients. PMID:23007194

  17. Facilitating text reading in posterior cortical atrophy

    PubMed Central

    Rajdev, Kishan; Shakespeare, Timothy J.; Leff, Alexander P.; Crutch, Sebastian J.

    2015-01-01

    Objective: We report (1) the quantitative investigation of text reading in posterior cortical atrophy (PCA), and (2) the effects of 2 novel software-based reading aids that result in dramatic improvements in the reading ability of patients with PCA. Methods: Reading performance, eye movements, and fixations were assessed in patients with PCA and typical Alzheimer disease and in healthy controls (experiment 1). Two reading aids (single- and double-word) were evaluated based on the notion that reducing the spatial and oculomotor demands of text reading might support reading in PCA (experiment 2). Results: Mean reading accuracy in patients with PCA was significantly worse (57%) compared with both patients with typical Alzheimer disease (98%) and healthy controls (99%); spatial aspects of passages were the primary determinants of text reading ability in PCA. Both aids led to considerable gains in reading accuracy (PCA mean reading accuracy: single-word reading aid = 96%; individual patient improvement range: 6%–270%) and self-rated measures of reading. Data suggest a greater efficiency of fixations and eye movements under the single-word reading aid in patients with PCA. Conclusions: These findings demonstrate how neurologic characterization of a neurodegenerative syndrome (PCA) and detailed cognitive analysis of an important everyday skill (reading) can combine to yield aids capable of supporting important everyday functional abilities. Classification of evidence: This study provides Class III evidence that for patients with PCA, 2 software-based reading aids (single-word and double-word) improve reading accuracy. PMID:26138948

  18. Posterior endoscopic discectomy: Results in 300 patients

    PubMed Central

    Kaushal, Mohinder; Sen, Ramesh

    2012-01-01

    Background: Posterior endoscopic discectomy is an established method for treatment of lumbar disc herniation. Many studies have not been reported in literature for lumbar discectomy by Destandau Endospine System. We report a series of 300 patients operated for lumbar dissectomy by Destandau Endospine system. Materials and Methods: A total of 300 patients suffering from lumbar disc herniations were operated between January 2002 and December 2008. All patients were operated as day care procedure. Technique comprised localization of symptomatic level followed by insertion of an endospine system devise through a 15 mm skin and fascial incision. Endoscopic discectomy is then carried out by conventional micro disc surgery instruments by minimal invasive route. The results were evaluated by Macnab's criteria after a minimum followup of 12 months and maximum up to 24 months. Results: Based on modified Macnab's criteria, 90% patients had excellent to good, 8% had fair, and 2% had poor results. The complications observed were discitis and dural tear in five patients each and nerve root injury in two patients. 90% patients were able to return to light and sedentary work with an average delay of 3 weeks and normal physical activities after 2 months. Conclusion: Edoscopic discectomy provides a safe and minimal access corridor for lumbar discectomy. The technique also allows early postoperative mobilization and faster return to work. PMID:22345812

  19. New infectious etiologies for posterior uveitis.

    PubMed

    Khairallah, Moncef; Kahloun, Rim; Ben Yahia, Salim; Jelliti, Bechir; Messaoud, Riadh

    2013-01-01

    Emergent and resurgent arthropod vector-borne diseases are major causes of systemic morbidity and death and expanding worldwide. Among them, viral and bacterial agents including West Nile virus, Dengue fever, Chikungunya, Rift Valley fever, and rickettsioses have been recently associated with an array of ocular manifestations. These include anterior uveitis, retinitis, chorioretinitis, retinal vasculitis and optic nerve involvement. Proper clinical diagnosis of any of these infectious diseases is based on epidemiological data, history, systemic symptoms and signs, and the pattern of ocular involvement. The diagnosis is usually confirmed by the detection of a specific antibody in serum. Ocular involvement associated with emergent infections usually has a self-limited course, but it can result in persistent visual impairment. There is currently no proven specific treatment for arboviral diseases, and therapy is mostly supportive. Vaccination for humans against these viruses is still in the research phase. Doxycycline is the treatment of choice for rickettsial diseases. Prevention, including public measures to reduce the number of mosquitoes and personal protection, remains the mainstay for arthropod vector disease control. Influenza A (H1N1) virus was responsible for a pandemic human influenza in 2009, and was recently associated with various posterior segment changes. PMID:23258387

  20. Posterior Reversible Leukoencephalopathy Syndrome Associated with Pazopanib

    PubMed Central

    Foerster, Robert; Welzel, Thomas; Debus, Juergen; Gruellich, Carsten; Jaeger, Dirk; Potthoff, Karin

    2013-01-01

    A 62-year-old female patient with metastatic renal cell carcinoma under third-line treatment with pazopanib for 8 weeks suddenly developed severe headaches, grand mal seizures and paresis of the left arm in combination with gait instability as well as nausea and vomiting during her vacation abroad. The emergency physician measured systolic blood pressure values over 300 mm Hg and suspected a stroke. The CT imaging without contrast agent in a local hospital did not show any pathologic findings despite bone metastases. The colleagues suspected cerebral metastases or meningeosis carcinomatosa and referred the patient to our department for further diagnostics and treatment planning. An MRI scan ruled out the suspected cerebral metastases or meningeosis carcinomatosa, but showed signs of reversible posterior leukoencephalopathy syndrome (RPLS) in the form of band-like hyperintensities as a sign of cytotoxic edema in the gray and white matter of the left parietal lobe. The patient then reported that similar blood pressure values had been measured shortly after the start of a first-line therapy with sunitinib, so that we discontinued the current treatment with pazopanib. Within 6 days the neurologic symptoms vanished and the patient was discharged. An intermittent hypertension persisted. A follow-up MRI 3 weeks later showed an RPLS-typical cortical infarction in the affected area. RPLS should be considered as the actual reason for neurologic findings in hypertensive patients with known metastatic cancers under tyrosine kinase inhibitor therapy. PMID:23626562

  1. Posterior Tibialis Tendon Dysfunction: Overview of Evaluation and Management.

    PubMed

    Yao, Kaihan; Yang, Timothy Xianyi; Yew, Wei Ping

    2015-06-01

    EDUCATIONAL OBJECTIVES As a result of reading this article, physicians should be able to: 1. Recognize posterior tibialis tendon dysfunction and begin to include it in differential diagnoses. 2. Recall the basic anatomy and pathology of the posterior tibialis tendon. 3. Assess a patient for posterior tibialis tendon dysfunction with the appropriate investigations and stratify the severity of the condition. 4. Develop and formulate a treatment plan for a patient with posterior tibialis tendon dysfunction. The posterior tibialis is a muscle in the deep posterior compartment of the calf that plays several key roles in the ankle and foot. Posterior tibialis tendon dysfunction is a complex but common and debilitating condition. Degenerative, inflammatory, functional, and traumatic etiologies have all been proposed. Despite being the leading cause of acquired flatfoot, it is often not recognized early enough. Knowledge of the anatomical considerations and etiology of posterior tibialis tendon dysfunction, as well as key concepts in its evaluation and management, will allow health care professionals to develop appropriate intervention strategies to prevent further development of flatfoot deformities. PMID:26091214

  2. Model estimates hurricane wind speed probabilities

    NASA Astrophysics Data System (ADS)

    Mumane, Richard J.; Barton, Chris; Collins, Eric; Donnelly, Jeffrey; Eisner, James; Emanuel, Kerry; Ginis, Isaac; Howard, Susan; Landsea, Chris; Liu, Kam-biu; Malmquist, David; McKay, Megan; Michaels, Anthony; Nelson, Norm; O Brien, James; Scott, David; Webb, Thompson, III

    In the United States, intense hurricanes (category 3, 4, and 5 on the Saffir/Simpson scale) with winds greater than 50 m s -1 have caused more damage than any other natural disaster [Pielke and Pielke, 1997]. Accurate estimates of wind speed exceedance probabilities (WSEP) due to intense hurricanes are therefore of great interest to (re)insurers, emergency planners, government officials, and populations in vulnerable coastal areas.The historical record of U.S. hurricane landfall is relatively complete only from about 1900, and most model estimates of WSEP are derived from this record. During the 1899-1998 period, only two category-5 and 16 category-4 hurricanes made landfall in the United States. The historical record therefore provides only a limited sample of the most intense hurricanes.

  3. Classifier calibration using splined empirical probabilities in clinical risk prediction.

    PubMed

    Gaudoin, Ren; Montana, Giovanni; Jones, Simon; Aylin, Paul; Bottle, Alex

    2015-06-01

    The aims of supervised machine learning (ML) applications fall into three broad categories: classification, ranking, and calibration/probability estimation. Many ML methods and evaluation techniques relate to the first two. Nevertheless, there are many applications where having an accurate probability estimate is of great importance. Deriving accurate probabilities from the output of a ML method is therefore an active area of research, resulting in several methods to turn a ranking into class probability estimates. In this manuscript we present a method, splined empirical probabilities, based on the receiver operating characteristic (ROC) to complement existing algorithms such as isotonic regression. Unlike most other methods it works with a cumulative quantity, the ROC curve, and as such can be tagged onto an ROC analysis with minor effort. On a diverse set of measures of the quality of probability estimates (Hosmer-Lemeshow, Kullback-Leibler divergence, differences in the cumulative distribution function) using simulated and real health care data, our approach compares favourably with the standard calibration method, the pool adjacent violators algorithm used to perform isotonic regression. PMID:24557734

  4. Posterior Corneal Surface Stability after Femtosecond Laser-Assisted Keratomileusis

    PubMed Central

    Cagini, Carlo; Messina, Marco; Lupidi, Marco; Piccinelli, Francesco; Fiore, Tito; Fruttini, Daniela; Spadea, Leopoldo

    2015-01-01

    The purpose of this study was to evaluate posterior corneal surface variation after femtosecond laser-assisted keratomileusis in patients with myopia and myopic astigmatism. Patients were evaluated by corneal tomography preoperatively and at 1, 6, and 12 months. We analyzed changes in the posterior corneal curvature, posterior corneal elevation, and anterior chamber depth. Moreover, we explored correlation between corneal ablation depth, residual corneal thickness, percentage of ablated corneal tissue, and preoperative corneal thickness. During follow-up, the posterior corneal surface did not have a significant forward corneal shift: no significant linear relationships emerged between the anterior displacement of the posterior corneal surface and corneal ablation depth, residual corneal thickness, or percentage of ablated corneal tissue. PMID:26483972

  5. Rare Posterior Pharyngeal Mass: Atypical Marginal Zone Hyperplasia.

    PubMed

    Şevik Eliçora, Sultan; Güven, Mehmet; Varli, Ali F; Yilmaz, Mahmut S; Alponat, Selin

    2016-03-01

    Cases of posterior pharyngeal masses are quite rare, and are typically derived from schwannoma or encephalocele, or are of vascular or infectious origin. They are clinically significant due to their tendency to cause airway obstruction. The aim of this study was to present a rare atypical marginal hyperplasia case of a posterior pharyngeal wall mass. A 10-year-old male was admitted to our clinic with dyspnea. A plane-surfaced 4×3×3 cm mass was observed on the posterior pharyngeal wall upon physical examination. The patient underwent magnetic resonance imaging and surgical treatment. Following excision of material from the patient's mass, a pathologic diagnosis of atypical marginal zone hyperplasia was made. Atypical marginal zone hyperplasia of the posterior pharyngeal wall has not yet been reported in the literature. Marginal zone hyperplasia associated with a lymphoproliferative disease should be considered when making differential diagnoses of posterior pharyngeal wall masses. PMID:26794707

  6. Emerging Techniques for Posterior Fixation of the Lumbar Spine.

    PubMed

    Verma, Kushagra; Boniello, Anthony; Rihn, Jeffrey

    2016-06-01

    Pedicle screw fixation is the preferred method of posterior fusion in lumbar spinal surgery. The technique provides three-column support of the vertebrae, contributing to the biomechanical strength of the construct. However, open pedicle screw fixation often necessitates wide posterior exposure and dissection with soft-tissue disruption of the facet joint. Alternative posterior fixation techniques have been developed to reduce surgical time, soft-tissue dissection, disruption of the adjacent facet joint capsule, neurologic risk, and implant cost. Results of these techniques are comparable to those of standard pedicle screw fixation systems. Certain patients, especially those at a lower risk of nonunion or those who require posterior fixation only as an adjunct to anterior column support, may benefit from the shorter surgical time and limited posterior exposure of the alternative techniques. However, the decreased rigidity of these alternative constructs can result in excessive motion, which can lead to nonunion and early hardware failure. PMID:27077477

  7. Medico-legal aspects of the use of posterior composites.

    PubMed

    Collins, M R

    1989-01-01

    Although there has been a significant rise in litigation involving dental treatment and an increase in the number of disciplinary actions being taken against dental surgeons, the Medical Defence Union has no evidence of a higher incidence of complaints when treatment has included the use of posterior composite restorations. The medico-legal implications in respect of posterior composites are no different from those for any other aspect of dental treatment when provided as part of treatment not carried out under National Health Service (General Dental Service) Regulations, however, the medico-legal implications of providing posterior composites as part of treatment carried out under National Health Service Regulations is much more complicated and the present situation is problematical for both the dentist and the patient. A full realisation of regulatory problems in respect of posterior composites is essential for those involved in the teaching of posterior composites. PMID:2732372

  8. Incompatible Stochastic Processes and Complex Probabilities

    NASA Technical Reports Server (NTRS)

    Zak, Michail

    1997-01-01

    The definition of conditional probabilities is based upon the existence of a joint probability. However, a reconstruction of the joint probability from given conditional probabilities imposes certain constraints upon the latter, so that if several conditional probabilities are chosen arbitrarily, the corresponding joint probability may not exist.

  9. Probability as a Physical Motive

    NASA Astrophysics Data System (ADS)

    Martin, Peter

    2007-06-01

    Recent theoretical progress in nonequilibrium thermodynamics, linking thephysical principle of Maximum Entropy Production (MEP) to the information-theoreticalMaxEnt principle of scientific inference, together with conjectures from theoreticalphysics that there may be no fundamental causal laws but only probabilities for physicalprocesses, and from evolutionary theory that biological systems expand the adjacentpossible as rapidly as possible, all lend credence to the proposition that probability shouldbe recognized as a fundamental physical motive. It is further proposed that spatial order andtemporal order are two aspects of the same thing, and that this is the essence of the secondlaw of thermodynamics.

  10. Interference of probabilities in dynamics

    SciTech Connect

    Zak, Michail

    2014-08-15

    A new class of dynamical systems with a preset type of interference of probabilities is introduced. It is obtained from the extension of the Madelung equation by replacing the quantum potential with a specially selected feedback from the Liouville equation. It has been proved that these systems are different from both Newtonian and quantum systems, but they can be useful for modeling spontaneous collective novelty phenomena when emerging outputs are qualitatively different from the weighted sum of individual inputs. Formation of language and fast decision-making process as potential applications of the probability interference is discussed.

  11. Knowledge typology for imprecise probabilities.

    SciTech Connect

    Wilson, G. D.; Zucker, L. J.

    2002-01-01

    When characterizing the reliability of a complex system there are often gaps in the data available for specific subsystems or other factors influencing total system reliability. At Los Alamos National Laboratory we employ ethnographic methods to elicit expert knowledge when traditional data is scarce. Typically, we elicit expert knowledge in probabilistic terms. This paper will explore how we might approach elicitation if methods other than probability (i.e., Dempster-Shafer, or fuzzy sets) prove more useful for quantifying certain types of expert knowledge. Specifically, we will consider if experts have different types of knowledge that may be better characterized in ways other than standard probability theory.

  12. More accurate time from the Heathkit most accurate clock

    NASA Astrophysics Data System (ADS)

    Tollefson, M. V.; Bloomer, R. H., Jr.

    1986-05-01

    The addition of an auxiliary circuit to the Heathkit GC-1000 clock is described. The circuit, which consists of two integrated circuits, two resistors, and three capacitors, will supply a more accurate timing pulse to the computer. The circuit contains two input signals and produces one output; the inputs are multiplexed seven-digit displays (two digits for hour, minute, and second, and one for tenths of a second) and the output appears as a string of about 10 low-going pulses about 1.25 ms in duration. Low pass filters (R1 and C1) are utilized to eliminate extraneous pulses. The materials and procedures for attaching the circuit to the clock are examined. The software for the data set ready signal, and the method for accurate timing of data collection are discussed. The accuracy of the clock is evaluated and it is observed that the circuit improves the correct time provided by the clock from + or - 29 ms to + or - 5 ms.

  13. Morphometric analysis of posterior fossa and foramen magnum

    PubMed Central

    Kanodia, Gautam; Parihar, Vijay; Yadav, Yad R; Bhatele, Pushp R; Sharma, Dhananjay

    2012-01-01

    Introduction: Configuration and size of the foramen magnum and posterior fossa plays an important role in the pathophysiology of the posterior fossa and craniovertebral junction disorders. This study is aimed to find out various dimensions of the foramen magnum and posterior fossa. Materials and Methods: This is a prospective study of 100 consecutive normal computerized tomography (CT) scans of posterior fossa and 100 dry adult skulls without any bony abnormality. The posterior fossa volume was calculated by abc/2 in method 1 and by advanced work station of CT scan in method 2. Various dimensions of posterior fossa and foramen magnum were also studied. Results: Age ranged from 16 to 89 years with a mean of 51.3 years. Mean height of posterior fossa were 3.01 cm (±0.22) and 3.52 (±0.43) cm in dry skull and CT scan group, respectively (P < 0.0001). Mean volume of posterior fossa were 157.88 (±27.94) cm3 and 159.58 (±25.73) cm3 by method 1 and method 2, respectively (P > 0.05). All the dimensions of posterior fossa and foramen magnum were larger in male as compared to female. Mean anteroposterior (AP), transverse diameter and surface area of the foramen magnum were 3.31 (±0.35) cm, 2.76 (±0.31) cm, and 729.15 (±124.87) mm2, respectively, in CT scan group as compared to 3.41 (±0.29) cm, 2.75 (±0.25) cm, and 747.67 (±108.60) mm2, respectively, in dry skull group. Conclusion: Normal values of posterior fossa and foramen magnum could serve as a future reference. Dry skull dimensions could be different from CT scan measurement. More studies are needed as there could be variations in dimensions in different regions in India PMID:23188974

  14. Facilitating normative judgments of conditional probability: frequency or nested sets?

    PubMed

    Yamagishi, Kimihiko

    2003-01-01

    Recent probability judgment research contrasts two opposing views. Some theorists have emphasized the role of frequency representations in facilitating probabilistic correctness; opponents have noted that visualizing the probabilistic structure of the task sufficiently facilitates normative reasoning. In the current experiment, the following conditional probability task, an isomorph of the "Problem of Three Prisoners" was tested. "A factory manufactures artificial gemstones. Each gemstone has a 1/3 chance of being blurred, a 1/3 chance of being cracked, and a 1/3 chance of being clear. An inspection machine removes all cracked gemstones, and retains all clear gemstones. However, the machine removes 1/2 of the blurred gemstones. What is the chance that a gemstone is blurred after the inspection?" A 2 x 2 design was administered. The first variable was the use of frequency instruction. The second manipulation was the use of a roulette-wheel diagram that illustrated a "nested-sets" relationship between the prior and the posterior probabilities. Results from two experiments showed that frequency alone had modest effects, while the nested-sets instruction achieved a superior facilitation of normative reasoning. The third experiment compared the roulette-wheel diagram to tree diagrams that also showed the nested-sets relationship. The roulette-wheel diagram outperformed the tree diagrams in facilitation of probabilistic reasoning. Implications for understanding the nature of intuitive probability judgments are discussed. PMID:12693194

  15. Posterior predictive checks of coalescent models: P2C2M, an R package.

    PubMed

    Gruenstaeudl, Michael; Reid, Noah M; Wheeler, Gregory L; Carstens, Bryan C

    2016-01-01

    Bayesian inference operates under the assumption that the empirical data are a good statistical fit to the analytical model, but this assumption can be challenging to evaluate. Here, we introduce a novel r package that utilizes posterior predictive simulation to evaluate the fit of the multispecies coalescent model used to estimate species trees. We conduct a simulation study to evaluate the consistency of different summary statistics in comparing posterior and posterior predictive distributions, the use of simulation replication in reducing error rates and the utility of parallel process invocation towards improving computation times. We also test P2C2M on two empirical data sets in which hybridization and gene flow are suspected of contributing to shared polymorphism, which is in violation with the coalescent model: Tamias chipmunks and Myotis bats. Our results indicate that (i) probability-based summary statistics display the lowest error rates, (ii) the implementation of simulation replication decreases the rate of type II errors, and (iii) our r package displays improved statistical power compared to previous implementations of this approach. When probabilistic summary statistics are used, P2C2M corroborates the assumption that genealogies collected from Tamias and Myotis are not a good fit to the multispecies coalescent model. Taken as a whole, our findings argue that an assessment of the fit of the multispecies coalescent model should accompany any phylogenetic analysis that estimates a species tree. PMID:26032939

  16. Impact probability calculations --- comparison of methods

    NASA Astrophysics Data System (ADS)

    Rickman, H.; Wiśniowski, T.; Wajer, P.; Gabryszewski, R.; Valsecchi, G.

    2014-07-01

    We compare three different methods of statistical impact-probability calculations: our Hill sphere method that uses a super-sizing of the planet's collisional cross-section, the numerical averaging of Wetherill's (1967) formula, and the novel MOID method developed by us. The first and third are Monte Carlo simulations methods. In the first we count the number of Hill sphere passages for a large, random sample of orbits. In the third we search for orbits with MOID less than the collisional radius in a similar sample, calculating the MOID by the method of Wiśniowski and Rickman (2013), after which we compute the encounter timing range leading to collision for each selected object and compare with the target's orbital period. Our extensive comparisons use a constant semi-major axis of 3.5 au for the projectiles, and we focus on the parametric plane of perihelion distance and inclination. They show an excellent agreement among all the methods under practically all circumstances. However, in the vicinity of the singularities appearing in the Wetherill formulae (zero relative inclination, and equal perihelion distances) we find that only the MOID method yields accurate results. Due to the approximations inherent in the other methods, the super-sizing method underestimates the impact probability, and the Wetherill averaging overestimates it. This work was supported by the Polish National Science Center under Grant No. 2011/01/B/ST9/05442.

  17. Achieving target voriconazole concentrations more accurately in children and adolescents.

    PubMed

    Neely, Michael; Margol, Ashley; Fu, Xiaowei; van Guilder, Michael; Bayard, David; Schumitzky, Alan; Orbach, Regina; Liu, Siyu; Louie, Stan; Hope, William

    2015-01-01

    Despite the documented benefit of voriconazole therapeutic drug monitoring, nonlinear pharmacokinetics make the timing of steady-state trough sampling and appropriate dose adjustments unpredictable by conventional methods. We developed a nonparametric population model with data from 141 previously richly sampled children and adults. We then used it in our multiple-model Bayesian adaptive control algorithm to predict measured concentrations and doses in a separate cohort of 33 pediatric patients aged 8 months to 17 years who were receiving voriconazole and enrolled in a pharmacokinetic study. Using all available samples to estimate the individual Bayesian posterior parameter values, the median percent prediction bias relative to a measured target trough concentration in the patients was 1.1% (interquartile range, -17.1 to 10%). Compared to the actual dose that resulted in the target concentration, the percent bias of the predicted dose was -0.7% (interquartile range, -7 to 20%). Using only trough concentrations to generate the Bayesian posterior parameter values, the target bias was 6.4% (interquartile range, -1.4 to 14.7%; P = 0.16 versus the full posterior parameter value) and the dose bias was -6.7% (interquartile range, -18.7 to 2.4%; P = 0.15). Use of a sample collected at an optimal time of 4 h after a dose, in addition to the trough concentration, resulted in a nonsignificantly improved target bias of 3.8% (interquartile range, -13.1 to 18%; P = 0.32) and a dose bias of -3.5% (interquartile range, -18 to 14%; P = 0.33). With the nonparametric population model and trough concentrations, our control algorithm can accurately manage voriconazole therapy in children independently of steady-state conditions, and it is generalizable to any drug with a nonparametric pharmacokinetic model. (This study has been registered at ClinicalTrials.gov under registration no. NCT01976078.). PMID:25779580

  18. Achieving Target Voriconazole Concentrations More Accurately in Children and Adolescents

    PubMed Central

    Margol, Ashley; Fu, Xiaowei; van Guilder, Michael; Bayard, David; Schumitzky, Alan; Orbach, Regina; Liu, Siyu; Louie, Stan; Hope, William

    2015-01-01

    Despite the documented benefit of voriconazole therapeutic drug monitoring, nonlinear pharmacokinetics make the timing of steady-state trough sampling and appropriate dose adjustments unpredictable by conventional methods. We developed a nonparametric population model with data from 141 previously richly sampled children and adults. We then used it in our multiple-model Bayesian adaptive control algorithm to predict measured concentrations and doses in a separate cohort of 33 pediatric patients aged 8 months to 17 years who were receiving voriconazole and enrolled in a pharmacokinetic study. Using all available samples to estimate the individual Bayesian posterior parameter values, the median percent prediction bias relative to a measured target trough concentration in the patients was 1.1% (interquartile range, −17.1 to 10%). Compared to the actual dose that resulted in the target concentration, the percent bias of the predicted dose was −0.7% (interquartile range, −7 to 20%). Using only trough concentrations to generate the Bayesian posterior parameter values, the target bias was 6.4% (interquartile range, −1.4 to 14.7%; P = 0.16 versus the full posterior parameter value) and the dose bias was −6.7% (interquartile range, −18.7 to 2.4%; P = 0.15). Use of a sample collected at an optimal time of 4 h after a dose, in addition to the trough concentration, resulted in a nonsignificantly improved target bias of 3.8% (interquartile range, −13.1 to 18%; P = 0.32) and a dose bias of −3.5% (interquartile range, −18 to 14%; P = 0.33). With the nonparametric population model and trough concentrations, our control algorithm can accurately manage voriconazole therapy in children independently of steady-state conditions, and it is generalizable to any drug with a nonparametric pharmacokinetic model. (This study has been registered at ClinicalTrials.gov under registration no. NCT01976078.) PMID:25779580

  19. Posterior Cruciate Ligament Retention versus Posterior Stabilization for Total Knee Arthroplasty: A Meta-Analysis

    PubMed Central

    Wang, Ying; Bian, Yanyan; Feng, Bin; Weng, Xisheng

    2016-01-01

    Introduction Although being debated for many years, the superiority of posterior cruciate-retaining (CR) total knee arthroplasty (TKA) and posterior-stabilized (PS) TKA remains controversial. We compare the knee scores, post-operative knee range of motion (ROM), radiological outcomes about knee kinematic and complications between CR TKA and PS TKA. Methods Literature published up to August 2015 was searched in PubMed, Embase and Cochrane databases, and meta-analysis was performed using the software, Review Manager version 5.3. Results Totally 14 random control trials (RCTs) on this topic were included for the analysis, which showed that PS and CR TKA had no significant difference in Knee Society knee Score (KSS), pain score (KSPS), Hospital for Special Surgery score (HSS), kinematic characteristics including postoperative component alignment, tibial posterior slope and joint line, and complication rate. However, PS TKA is superior to CR TKA regarding post-operative knee range of motion (ROM) [Random Effect model (RE), Mean Difference (MD) = -7.07, 95% Confidential Interval (CI) -10.50 to -3.65, p<0.0001], improvement of ROM (Fixed Effect model (FE), MD = -5.66, 95% CI -10.79 to -0.53, p = 0.03) and femoral-tibial angle [FE, MD = 0.85, 95% CI 0.46 to 1.25, p<0.0001]. Conclusions There are no clinically relevant differences between CR and PS TKA in terms of clinical, functional, radiological outcome, and complications, while PS TKA is superior to CR TKA in respects of ROM, while whether this superiority matters or not in clinical practice still needs further investigation and longer follow-up. PMID:26824368

  20. GPS: Geometry, Probability, and Statistics

    ERIC Educational Resources Information Center

    Field, Mike

    2012-01-01

    It might be said that for most occupations there is now less of a need for mathematics than there was say fifty years ago. But, the author argues, geometry, probability, and statistics constitute essential knowledge for everyone. Maybe not the geometry of Euclid, but certainly geometrical ways of thinking that might enable us to describe the world

  1. Rare and Exotic Probability Bugs

    ERIC Educational Resources Information Center

    Kennis, James R.

    2009-01-01

    This article examines some of the various judgmental errors and rationales that high school students make when attempting to solve basic probability exercises. Many of these errors allow the students to arrive at a correct answer and, thus, need to be examined more closely. (Contains 4 tables.)

  2. On probability-possibility transformations

    NASA Technical Reports Server (NTRS)

    Klir, George J.; Parviz, Behzad

    1992-01-01

    Several probability-possibility transformations are compared in terms of the closeness of preserving second-order properties. The comparison is based on experimental results obtained by computer simulation. Two second-order properties are involved in this study: noninteraction of two distributions and projections of a joint distribution.

  3. GPS: Geometry, Probability, and Statistics

    ERIC Educational Resources Information Center

    Field, Mike

    2012-01-01

    It might be said that for most occupations there is now less of a need for mathematics than there was say fifty years ago. But, the author argues, geometry, probability, and statistics constitute essential knowledge for everyone. Maybe not the geometry of Euclid, but certainly geometrical ways of thinking that might enable us to describe the world…

  4. Dynamic SEP event probability forecasts

    NASA Astrophysics Data System (ADS)

    Kahler, S. W.; Ling, A.

    2015-10-01

    The forecasting of solar energetic particle (SEP) event probabilities at Earth has been based primarily on the estimates of magnetic free energy in active regions and on the observations of peak fluxes and fluences of large (≥ M2) solar X-ray flares. These forecasts are typically issued for the next 24 h or with no definite expiration time, which can be deficient for time-critical operations when no SEP event appears following a large X-ray flare. It is therefore important to decrease the event probability forecast with time as a SEP event fails to appear. We use the NOAA listing of major (≥10 pfu) SEP events from 1976 to 2014 to plot the delay times from X-ray peaks to SEP threshold onsets as a function of solar source longitude. An algorithm is derived to decrease the SEP event probabilities with time when no event is observed to reach the 10 pfu threshold. In addition, we use known SEP event size distributions to modify probability forecasts when SEP intensity increases occur below the 10 pfu event threshold. An algorithm to provide a dynamic SEP event forecast, Pd, for both situations of SEP intensities following a large flare is derived.

  5. [Seven cases of posterior cerebral artery aneurysms].

    PubMed

    Gi, Hidefuku; Uno, Jyunji; Ikai, Yoshiaki; Inoha, Satoshi; Koga, Hiromichi; Yamaguchi, Shinya; Nagaoka, Shintaro

    2007-04-01

    In a period of ten years, since January 1996, we have encountered seven cases of posterior cerebral artery aneurysms (0.58% of surgically treated 1027 aneurysms in our hospital). Six of these cases were females (from 39 years old to 73 years old, average 54.5 years old). In five of the cases, neck clippings were performed, using the pterional approach for one P1 and one P2a aneurysm, the remaining three were clipping using the subtemporal approach for one P2a and two P2p aneurysms. In one case diagnosed as "unknown SAH" by typical findings of the CT scan and normal four-vessel study at the time of admission. The second vertebral angiography (two weeks later) revealed a P2a aneurysm. Such a case attracted our interest in the clinic, because many similar cases might have been diagnosed as "unknown SAH". In the case of a 42-year-old male with intracerebral hematoma, four-vessel study made a definite diagnosis as moyamoya disease and revealed a P2a aneurysm, which we cured by embolization of GDC for the preservation of anastomosis networks which had already been formed. Intravascular embolization is very effective, but sufficient studies are required before applying it in the cases of large and/or thrombosed aneurysms. We described surgical approaches about pterional, subtemporal and transchoroidal approaches and discussed some of the differences in the classification methods of Pia, Yasargil, Zear & Rhoton and Seoane. In particular, attention is necessary because we have confused Yasargil's classification with Zeal & Rhoton's classifications by using of the same notation, "Pn". PMID:17424966

  6. Convergent type proximal radioulnar translocation complicating posterior elbow dislocation: watch out for dual dislocations in children's elbows.

    PubMed

    Antonis, Konstantinos; Leonidou, Omiros A; Sbonias, Georgios; Fligger, Ioannis

    2011-05-01

    Proximal radioulnar translocation associated with posterior dislocation of the elbow is an extremely rare combination of trauma to the elbow in children. We report on the successful and sequential closed reduction of both these dislocations in a 10-year-old girl in which the translocation of the forearm bones was initially missed. A concomitant fracture would have probably precluded an ideal outcome as we note from the literature review on this problem. PMID:21490535

  7. Maximum Probability Reaction Sequences in Stochastic Chemical Kinetic Systems

    PubMed Central

    Salehi, Maryam; Perkins, Theodore J.

    2010-01-01

    The detailed behavior of many molecular processes in the cell, such as protein folding, protein complex assembly, and gene regulation, transcription and translation, can often be accurately captured by stochastic chemical kinetic models. We investigate a novel computational problem involving these models – that of finding the most-probable sequence of reactions that connects two or more states of the system observed at different times. We describe an efficient method for computing the probability of a given reaction sequence, but argue that computing most-probable reaction sequences is EXPSPACE-hard. We develop exact (exhaustive) and approximate algorithms for finding most-probable reaction sequences. We evaluate these methods on test problems relating to a recently-proposed stochastic model of folding of the Trp-cage peptide. Our results provide new computational tools for analyzing stochastic chemical models, and demonstrate their utility in illuminating the behavior of real-world systems. PMID:21629860

  8. Maximum Probability Reaction Sequences in Stochastic Chemical Kinetic Systems

    PubMed Central

    Salehi, Maryam; Perkins, Theodore J.

    2010-01-01

    The detailed behavior of many molecular processes in the cell, such as protein folding, protein complex assembly, and gene regulation, transcription and translation, can often be accurately captured by stochastic chemical kinetic models. We investigate a novel computational problem involving these models – that of finding the most-probable sequence of reactions that connects two or more states of the system observed at different times. We describe an efficient method for computing the probability of a given reaction sequence, but argue that computing most-probable reaction sequences is EXPSPACE-hard. We develop exact (exhaustive) and approximate algorithms for finding most-probable reaction sequences. We evaluate these methods on test problems relating to a recently-proposed stochastic model of folding of the Trp-cage peptide. Our results provide new computational tools for analyzing stochastic chemical models, and demonstrate their utility in illuminating the behavior of real-world systems. PMID:21441987

  9. Digging up the recent Spanish memory: genetic identification of human remains from mass graves of the Spanish Civil War and posterior dictatorship.

    PubMed

    Baeta, Miriam; Núñez, Carolina; Cardoso, Sergio; Palencia-Madrid, Leire; Herrasti, Lourdes; Etxeberria, Francisco; de Pancorbo, Marian M

    2015-11-01

    The Spanish Civil War (1936-1939) and posterior dictatorship (until 1970s) stands as one of the major conflicts in the recent history of Spain. It led to nearly two hundred thousand men and women executed or murdered extra-judicially or after dubious legal procedures. Nowadays, most of them remain unidentified or even buried in irretraceable mass graves across Spain. Here, we present the genetic identification of human remains found in 26 mass graves located in Northern Spain. A total of 252 post-mortem remains were analyzed and compared to 186 relatives, allowing the identification of 87 victims. Overall, a significant success of DNA profiling was reached, since informative profiles (≥ 12 STRs and/or mitochondrial DNA profile) were obtained in 85.71% of the remains. This high performance in DNA profiling from challenging samples demonstrated the efficacy of DNA extraction and amplification methods used herein, given that only around 14.29% of the samples did not provide an informative genetic profile for the analysis performed, probably due to the presence of degraded and/or limited DNA in these remains. However, this study shows a partial identification success rate, which is clearly a consequence of the lack of both appropriate family members for genetic comparisons and accurate information about the victims' location. Hence, further perseverance in the exhumation of other intact graves as well as in the search of more alleged relatives is crucial in order to facilitate and increase the number of genetic identifications. PMID:26378723

  10. TEASING: a fast and accurate approximation for the low multipole likelihood of the cosmic microwave background temperature

    NASA Astrophysics Data System (ADS)

    Benabed, K.; Cardoso, J.-F.; Prunet, S.; Hivon, E.

    2009-11-01

    We propose a novel approximation to the low-l joint likelihood of the angular spectrum Cl of masked cosmic microwave background temperature maps which is both very accurate and very fast to evaluate. We show that, for a flat prior, the posterior distribution of each Cl closely follows an inverse gamma distribution even with partial sky coverage and that the posterior correlation is weak enough that a copula approximation to the joint likelihood is quite accurate. In this paper, the quantities needed to build such a copula approximation (inverse gamma parameters at each angular frequency and a correlation matrix) are computed from an exploration of the posterior using adaptive importance sampling. The accuracy of the proposed approximation is assessed using statistical criteria as well as a mock cosmological parameter fit. When applied to the Wilkinson Microwave Anisotropy Probe 5 data set, the copula approximation yields cosmological parameter estimates at the same level of accuracy as the best current techniques.

  11. Fast and accurate database searches with MS-GF+Percolator.

    PubMed

    Granholm, Viktor; Kim, Sangtae; Navarro, José C F; Sjölund, Erik; Smith, Richard D; Käll, Lukas

    2014-02-01

    One can interpret fragmentation spectra stemming from peptides in mass-spectrometry-based proteomics experiments using so-called database search engines. Frequently, one also runs post-processors such as Percolator to assess the confidence, infer unique peptides, and increase the number of identifications. A recent search engine, MS-GF+, has shown promising results, due to a new and efficient scoring algorithm. However, MS-GF+ provides few statistical estimates about the peptide-spectrum matches, hence limiting the biological interpretation. Here, we enabled Percolator processing for MS-GF+ output and observed an increased number of identified peptides for a wide variety of data sets. In addition, Percolator directly reports p values and false discovery rate estimates, such as q values and posterior error probabilities, for peptide-spectrum matches, peptides, and proteins, functions that are useful for the whole proteomics community. PMID:24344789

  12. Fast and accurate database searches with MS-GF+Percolator

    SciTech Connect

    Granholm, Viktor; Kim, Sangtae; Navarro, Jose' C.; Sjolund, Erik; Smith, Richard D.; Kall, Lukas

    2014-02-28

    To identify peptides and proteins from the large number of fragmentation spectra in mass spectrometrybased proteomics, researches commonly employ so called database search engines. Additionally, postprocessors like Percolator have been used on the results from such search engines, to assess confidence, infer peptides and generally increase the number of identifications. A recent search engine, MS-GF+, has previously been showed to out-perform these classical search engines in terms of the number of identified spectra. However, MS-GF+ generates only limited statistical estimates of the results, hence hampering the biological interpretation. Here, we enabled Percolator-processing for MS-GF+ output, and observed an increased number of identified peptides for a wide variety of datasets. In addition, Percolator directly reports false discovery rate estimates, such as q values and posterior error probabilities, as well as p values, for peptide-spectrum matches, peptides and proteins, functions useful for the whole proteomics community.

  13. Ultrasound combined with electrodiagnosis improves lesion localization and outcome in posterior interosseous neuropathy

    PubMed Central

    Wininger, Yevgeniya Dvorkin; Buckalew, Neilly A.; Kaufmann, Robert A.; Munin, Michael C.

    2016-01-01

    INTRODUCTION Posterior interosseous nerve (PIN) syndrome is a rare compression neuropathy. Electrodiagnostic studies (EDX) combined with neuromuscular ultrasound (US) enable precise lesion localization and may improve patient outcome. METHODS In 4 patients with finger extension weakness, US was used to accurately localize concentric EMG needle placement in PIN muscles and to visualize the lesion site. RESULTS EMG with US guidance showed decreased recruitment with abnormal configuration in PIN muscles. Active denervation was not always observed. US scanning demonstrated larger PIN diameter in the affected arm. All patients had surgical intervention to confirm EDX and US findings with improved outcome on follow-up. CONCLUSION These cases demonstrate the benefits of augmenting EDX with US by guiding accurate electrode localization and providing diagnostic information about lesion location. PMID:26206065

  14. Incidence and surgical importance of the posterior gastric artery.

    PubMed Central

    Suzuki, K; Prates, J C; DiDio, L J

    1978-01-01

    In a series of 61 adult cadavers, the posterior gastric artery was found in 38 (62.3%), originating from the superior aspect of the mid-third of the splenic artery. The posterior gastric artery, running behind the parietal peritoneum of the omental bursa, produced a peritoneal fold before reaching the posterior wall of the superior portion of the gastric body, near the cardiac region, and the fundus. Its high incidence, hidden origin, deep course, and distribution make this artery very important for surgical procedures relating to the stomach, pancreas, spleen, and celiac region. It may be crucial, especially if partial gastric resection of splenectomy have obliterated other gastric vessels. PMID:629615

  15. Asystole during posterior fossa surgery: Report of two cases.

    PubMed

    Goyal, Keshav; Philip, Frenny Ann; Rath, Girija Prasad; Mahajan, Charu; Sujatha, M; Bharti, Sachidanand Jee; Gupta, Nidhi

    2012-04-01

    Asystole during posterior fossa neurosurgical procedures is not uncommon. Various causes have been implicated, especially when surgical manipulation is carried out in the vicinity of the brain stem. The trigemino-cardiac reflex has been attributed as one of the causes. Here, we report two cases who suffered asystole during the resection of posterior fossa tumors. The vago-glossopharyngeal reflex and the direct stimulation of the brainstem were hypothesized as the causes of asytole. These episodes resolved spontaneously following withdrawal of the surgical stimulus emphasizing the importance of anticipation and vigilance during critical moments of tumor dissection during posterior fossa surgery. PMID:22870159

  16. A new condensable composite for the restoration of posterior teeth.

    PubMed

    Leinfelder, K; Prasad, A

    1998-02-01

    Undoubtedly the greatest resistance of clinicians to use composite resins in posterior teeth relates to technique sensitivity, time consumption, and complexity. Placing conventional posterior composite resins does not take into account that composites differ considerably from amalgam. This is particularly true with respect to its physical characteristics, especially insertion and packing properties. The development of a posterior composite resin that can be placed by an amalgam carrier and subsequently packed or condensed as an amalgam, should assist clinicians greatly in their ability to successfully restore class II cavity preparations. Acknowledgment is expressed to Bruce Small, DMD, for the clinical dentistry and slides. PMID:9560676

  17. Asystole during posterior fossa surgery: Report of two cases

    PubMed Central

    Goyal, Keshav; Philip, Frenny Ann; Rath, Girija Prasad; Mahajan, Charu; Sujatha, M.; Bharti, Sachidanand Jee; Gupta, Nidhi

    2012-01-01

    Asystole during posterior fossa neurosurgical procedures is not uncommon. Various causes have been implicated, especially when surgical manipulation is carried out in the vicinity of the brain stem. The trigemino-cardiac reflex has been attributed as one of the causes. Here, we report two cases who suffered asystole during the resection of posterior fossa tumors. The vago-glossopharyngeal reflex and the direct stimulation of the brainstem were hypothesized as the causes of asytole. These episodes resolved spontaneously following withdrawal of the surgical stimulus emphasizing the importance of anticipation and vigilance during critical moments of tumor dissection during posterior fossa surgery. PMID:22870159

  18. Posterior cortical atrophy: an atypical variant of Alzheimer disease.

    PubMed

    Suárez-González, Aida; Henley, Susie M; Walton, Jill; Crutch, Sebastian J

    2015-06-01

    Posterior cortical atrophy (PCA) is a neurodegenerative syndrome characterized by striking progressive visual impairment and a pattern of atrophy mainly involving posterior cortices. PCA is the most frequent atypical presentation of Alzheimer disease. The purpose of this article is to provide a summary of PCA's neuropsychiatric manifestations. Emotional and psychotic symptoms are discussed in the context of signal characteristic features of the PCA syndrome (the early onset, focal loss of visual perception, focal posterior brain atrophy) and the underlying cause of the disease. The authors' experience with psychotherapeutic intervention and PCA support groups is shared in detail. PMID:25998111

  19. Probability, Information and Statistical Physics

    NASA Astrophysics Data System (ADS)

    Kuzemsky, A. L.

    2016-03-01

    In this short survey review we discuss foundational issues of the probabilistic approach to information theory and statistical mechanics from a unified standpoint. Emphasis is on the inter-relations between theories. The basic aim is tutorial, i.e. to carry out a basic introduction to the analysis and applications of probabilistic concepts to the description of various aspects of complexity and stochasticity. We consider probability as a foundational concept in statistical mechanics and review selected advances in the theoretical understanding of interrelation of the probability, information and statistical description with regard to basic notions of statistical mechanics of complex systems. It includes also a synthesis of past and present researches and a survey of methodology. The purpose of this terse overview is to discuss and partially describe those probabilistic methods and approaches that are used in statistical mechanics with the purpose of making these ideas easier to understanding and to apply.

  20. On numerically accurate finite element

    NASA Technical Reports Server (NTRS)

    Nagtegaal, J. C.; Parks, D. M.; Rice, J. R.

    1974-01-01

    A general criterion for testing a mesh with topologically similar repeat units is given, and the analysis shows that only a few conventional element types and arrangements are, or can be made suitable for computations in the fully plastic range. Further, a new variational principle, which can easily and simply be incorporated into an existing finite element program, is presented. This allows accurate computations to be made even for element designs that would not normally be suitable. Numerical results are given for three plane strain problems, namely pure bending of a beam, a thick-walled tube under pressure, and a deep double edge cracked tensile specimen. The effects of various element designs and of the new variational procedure are illustrated. Elastic-plastic computation at finite strain are discussed.

  1. Accurate thickness measurement of graphene.

    PubMed

    Shearer, Cameron J; Slattery, Ashley D; Stapleton, Andrew J; Shapter, Joseph G; Gibson, Christopher T

    2016-03-29

    Graphene has emerged as a material with a vast variety of applications. The electronic, optical and mechanical properties of graphene are strongly influenced by the number of layers present in a sample. As a result, the dimensional characterization of graphene films is crucial, especially with the continued development of new synthesis methods and applications. A number of techniques exist to determine the thickness of graphene films including optical contrast, Raman scattering and scanning probe microscopy techniques. Atomic force microscopy (AFM), in particular, is used extensively since it provides three-dimensional images that enable the measurement of the lateral dimensions of graphene films as well as the thickness, and by extension the number of layers present. However, in the literature AFM has proven to be inaccurate with a wide range of measured values for single layer graphene thickness reported (between 0.4 and 1.7 nm). This discrepancy has been attributed to tip-surface interactions, image feedback settings and surface chemistry. In this work, we use standard and carbon nanotube modified AFM probes and a relatively new AFM imaging mode known as PeakForce tapping mode to establish a protocol that will allow users to accurately determine the thickness of graphene films. In particular, the error in measuring the first layer is reduced from 0.1-1.3 nm to 0.1-0.3 nm. Furthermore, in the process we establish that the graphene-substrate adsorbate layer and imaging force, in particular the pressure the tip exerts on the surface, are crucial components in the accurate measurement of graphene using AFM. These findings can be applied to other 2D materials. PMID:26894444

  2. Accurate thickness measurement of graphene

    NASA Astrophysics Data System (ADS)

    Shearer, Cameron J.; Slattery, Ashley D.; Stapleton, Andrew J.; Shapter, Joseph G.; Gibson, Christopher T.

    2016-03-01

    Graphene has emerged as a material with a vast variety of applications. The electronic, optical and mechanical properties of graphene are strongly influenced by the number of layers present in a sample. As a result, the dimensional characterization of graphene films is crucial, especially with the continued development of new synthesis methods and applications. A number of techniques exist to determine the thickness of graphene films including optical contrast, Raman scattering and scanning probe microscopy techniques. Atomic force microscopy (AFM), in particular, is used extensively since it provides three-dimensional images that enable the measurement of the lateral dimensions of graphene films as well as the thickness, and by extension the number of layers present. However, in the literature AFM has proven to be inaccurate with a wide range of measured values for single layer graphene thickness reported (between 0.4 and 1.7 nm). This discrepancy has been attributed to tip-surface interactions, image feedback settings and surface chemistry. In this work, we use standard and carbon nanotube modified AFM probes and a relatively new AFM imaging mode known as PeakForce tapping mode to establish a protocol that will allow users to accurately determine the thickness of graphene films. In particular, the error in measuring the first layer is reduced from 0.1-1.3 nm to 0.1-0.3 nm. Furthermore, in the process we establish that the graphene-substrate adsorbate layer and imaging force, in particular the pressure the tip exerts on the surface, are crucial components in the accurate measurement of graphene using AFM. These findings can be applied to other 2D materials.

  3. Facial dimensions, bite force and masticatory muscle thickness in preschool children with functional posterior crossbite.

    PubMed

    Castelo, Paula Midori; Bonjardim, Leonardo Rigoldi; Pereira, Luciano José; Gavião, Maria Beatriz Duarte

    2008-01-01

    Posterior crossbite may affect craniofacial growth and development. Thus, this study aimed to associate facial dimensions (by standardized frontal photographs) to masseter and anterior portion of the temporal muscle thickness (by ultrasonography) and maximal bilateral bite force in 49 children with deciduous and early mixed dentitions. They were distributed in four groups: deciduous-normal occlusion (DNO, n = 15), deciduous-crossbite (DCB, n = 10), mixed-normal occlusion (MNO, n = 13) and mixed-crossbite (MCB, n = 11). Anterior facial height (AFH), bizygomatic width (FWB), and intergonial width (FWI) were determined and associated with muscle thickness and bite force, applying Pearsons coefficients and multiple logistic regression, with age, gender, body weight and height as the covariates. FWB and FWI were correlated positively with the masseter thickness, whereas AFH/FWB and AFH/FWI ratios had negative correlation, except in the DNO group. The correlation between AFH/FWB and bite force in the MCB group was significantly negative. A higher AFH/FWB in MNO and MCB led to a significantly higher probability for functional crossbite development. In the studied sample, it was observed that children in the early mixed dentition with a long-face trend showed lower bite force and higher probability to present functional posterior crossbite, without significant influence of the covariates. PMID:18425245

  4. Bayesian Retrieval of Complete Posterior PDFs of Oceanic Rain Rate From Microwave Observations

    NASA Technical Reports Server (NTRS)

    Chiu, J. Christine; Petty, Grant W.

    2005-01-01

    This paper presents a new Bayesian algorithm for retrieving surface rain rate from Tropical Rainfall Measurements Mission (TRMM) Microwave Imager (TMI) over the ocean, along with validations against estimates from the TRMM Precipitation Radar (PR). The Bayesian approach offers a rigorous basis for optimally combining multichannel observations with prior knowledge. While other rain rate algorithms have been published that are based at least partly on Bayesian reasoning, this is believed to be the first self-contained algorithm that fully exploits Bayes Theorem to yield not just a single rain rate, but rather a continuous posterior probability distribution of rain rate. To advance our understanding of theoretical benefits of the Bayesian approach, we have conducted sensitivity analyses based on two synthetic datasets for which the true conditional and prior distribution are known. Results demonstrate that even when the prior and conditional likelihoods are specified perfectly, biased retrievals may occur at high rain rates. This bias is not the result of a defect of the Bayesian formalism but rather represents the expected outcome when the physical constraint imposed by the radiometric observations is weak, due to saturation effects. It is also suggested that the choice of the estimators and the prior information are both crucial to the retrieval. In addition, the performance of our Bayesian algorithm is found to be comparable to that of other benchmark algorithms in real-world applications, while having the additional advantage of providing a complete continuous posterior probability distribution of surface rain rate.

  5. Entropy in probability and statistics

    SciTech Connect

    Rolke, W.A.

    1992-01-01

    The author develops a theory of entropy, where entropy is defined as the Legendre-Fenchel transform of the logarithmic moment generating function of a probability measure on a Banach space. A variety of properties relating the probability measure and its entropy are proven. It is shown that the entropy of a large class of stochastic processes can be approximated by the entropies of the finite-dimensional distributions of the process. For several types of measures the author finds explicit formulas for the entropy, for example for stochastic processes with independent increments and for Gaussian processes. For the entropy of Markov chains, evaluated at the observations of the process, the author proves a central limit theorem. Theorems relating weak convergence of probability measures on a finite dimensional space and pointwise convergence of their entropies are developed and then used to give a new proof of Donsker's theorem. Finally the use of entropy in statistics is discussed. The author shows the connection between entropy and Kullback's minimum discrimination information. A central limit theorem yields a test for the independence of a sequence of observations.

  6. Electrofishing capture probability of smallmouth bass in streams

    USGS Publications Warehouse

    Dauwalter, D.C.; Fisher, W.L.

    2007-01-01

    Abundance estimation is an integral part of understanding the ecology and advancing the management of fish populations and communities. Mark-recapture and removal methods are commonly used to estimate the abundance of stream fishes. Alternatively, abundance can be estimated by dividing the number of individuals sampled by the probability of capture. We conducted a mark-recapture study and used multiple repeated-measures logistic regression to determine the influence of fish size, sampling procedures, and stream habitat variables on the cumulative capture probability for smallmouth bass Micropterus dolomieu in two eastern Oklahoma streams. The predicted capture probability was used to adjust the number of individuals sampled to obtain abundance estimates. The observed capture probabilities were higher for larger fish and decreased with successive electrofishing passes for larger fish only. Model selection suggested that the number of electrofishing passes, fish length, and mean thalweg depth affected capture probabilities the most; there was little evidence for any effect of electrofishing power density and woody debris density on capture probability. Leave-one-out cross validation showed that the cumulative capture probability model predicts smallmouth abundance accurately. ?? Copyright by the American Fisheries Society 2007.

  7. The Prediction of Spatial Aftershock Probabilities (PRESAP)

    NASA Astrophysics Data System (ADS)

    McCloskey, J.

    2003-12-01

    It is now widely accepted that the goal of deterministic earthquake prediction is unattainable in the short term and may even be forbidden by nonlinearity in the generating dynamics. This nonlinearity does not, however, preclude the estimation of earthquake probability and, in particular, how this probability might change in space and time; earthquake hazard estimation might be possible in the absence of earthquake prediction. Recently, there has been a major development in the understanding of stress triggering of earthquakes which allows accurate calculation of the spatial variation of aftershock probability following any large earthquake. Over the past few years this Coulomb stress technique (CST) has been the subject of intensive study in the geophysics literature and has been extremely successful in explaining the spatial distribution of aftershocks following several major earthquakes. The power of current micro-computers, the great number of local, telemeter seismic networks, the rapid acquisition of data from satellites coupled with the speed of modern telecommunications and data transfer all mean that it may be possible that these new techniques could be applied in a forward sense. In other words, it is theoretically possible today to make predictions of the likely spatial distribution of aftershocks in near-real-time following a large earthquake. Approximate versions of such predictions could be available within, say, 0.1 days after the mainshock and might be continually refined and updated over the next 100 days. The European Commission has recently provided funding for a project to assess the extent to which it is currently possible to move CST predictions into a practically useful time frame so that low-confidence estimates of aftershock probability might be made within a few hours of an event and improved in near-real-time, as data of better quality become available over the following day to tens of days. Specifically, the project aim is to assess the extent to which this is scientifically feasible in terms of our understanding of the physical phenomena which control the variation of seismicity following a large event due to stress redistribution and practically possible given present limitations on data availability, data quality and computational or data transfer speeds. The project is divided into a number of elements designed to reflect the temporal sequence of tasks that must be undertaken for the prediction of aftershock hazard. These tasks include determining a time-indexed sequence of slip distributions for both real and synthetic events, calculating a suite of time-indexed stress perturbations and quantitatively comprising predicted and observed aftershock distributions, and developing techniques for predicting likely strong ground motion from the predicted spatial distribution of aftershocks.

  8. Mandibular fracture patterns consistent with posterior maxillary fractures involving the posterior maxillary sinus, pterygoid plate or both: CT characteristics

    PubMed Central

    Sukegawa, S; Kanno, T; Fujita, G; Yamamoto, N; Furuki, Y; Michizawa, M

    2014-01-01

    Objectives: The aim of this study was to determine the incidence of posterior maxillary fractures involving the posterior maxillary sinus wall, pterygoid plate or both, unrelated to major midface fractures in patients with mandibular fractures, and to characterize associated fractures. Methods: A CT study was performed in patients with mandibular fractures to identify posterior maxillary fractures. Patients aged under 16 years, those with mandibular fractures involving only dentoalveolar components and those with concurrent major midfacial fractures were excluded. Results: 13 (6.7%) of 194 patients with mandibular fractures also had posterior maxillary fractures (case group). The injury pattern correlated with the external force directed to the lateral side of the mandible (p < 0.001), alcohol consumption (p = 0.049), the presence of multifocal fractures (p = 0.002) and the fracture regions in the symphysis/parasymphysis (p = 0.001) and the angle/ramus (p = 0.001). No significant difference between the case and non-case groups was seen for age, sex or cause of trauma. Non-displaced fractures in the ipsilateral posterior mandible occurred with significant frequency (p = 0.001) when the posterior maxillary fractures involved only the sinus. Conclusions: Mandibular fractures accompanied by posterior maxillary fractures are not rare. The finding of a unilateral posterior maxillary fracture on CT may aid the efficient radiological examination of the mandible based on possible patterns of associated fractures, as follows: in the ipsilateral posterior region as a direct fracture when the impact is a medially directed force, and in the symphysis/parasymphysis or contralateral condylar neck as an indirect fracture. PMID:24336313

  9. Global posterior densities for sensor management

    NASA Astrophysics Data System (ADS)

    Mahler, Ronald P. S.

    1998-07-01

    In several recent papers and a new book, Mathematics of Data FUsion, we have shown how finite-set statistics (FISST), a special case of random set theory, provides a theoretically rigorous foundation for many aspects of data fusion. In particular, we demonstrated that this theory provides a fundamental new approach to the problem of determining optimal dwell allocations, mode selections, and servo parameters for reassignable and/or multimode sensor. The basic approach relied on the fact that FISST provides a means of mathematically transforming multisensor, multitarget sensor management problems into conventional nonlinear optimal control problems. In this paper we show that the approach can be extended to include the possibility that the sensor may be distributed among many platforms. We also briefly describe a special cases of finite-set statistics called 'joint multitarget probabilities' or 'JMP', which has been applied to another sensor management approach by Musick, Kastella, and Mahler.

  10. Survival analysis of posterior restorations using an insurance claims database.

    PubMed

    Bogacki, R E; Hunt, R J; del Aguila, M; Smith, W R

    2002-01-01

    This study indicates that composite restorations do not last as long as amalgam restorations in posterior teeth. Dentists can use this information to better inform their patients when choosing restorative materials. PMID:12216568

  11. Abnormalities of fixation, saccade and pursuit in posterior cortical atrophy.

    PubMed

    Shakespeare, Timothy J; Kaski, Diego; Yong, Keir X X; Paterson, Ross W; Slattery, Catherine F; Ryan, Natalie S; Schott, Jonathan M; Crutch, Sebastian J

    2015-07-01

    The clinico-neuroradiological syndrome posterior cortical atrophy is the cardinal 'visual dementia' and most common atypical Alzheimer's disease phenotype, offering insights into mechanisms underlying clinical heterogeneity, pathological propagation and basic visual phenomena (e.g. visual crowding). Given the extensive attention paid to patients' (higher order) perceptual function, it is surprising that there have been no systematic analyses of basic oculomotor function in this population. Here 20 patients with posterior cortical atrophy, 17 patients with typical Alzheimer's disease and 22 healthy controls completed tests of fixation, saccade (including fixation/target gap and overlap conditions) and smooth pursuit eye movements using an infrared pupil-tracking system. Participants underwent detailed neuropsychological and neurological examinations, with a proportion also undertaking brain imaging and analysis of molecular pathology. In contrast to informal clinical evaluations of oculomotor dysfunction frequency (previous studies: 38%, current clinical examination: 33%), detailed eyetracking investigations revealed eye movement abnormalities in 80% of patients with posterior cortical atrophy (compared to 17% typical Alzheimer's disease, 5% controls). The greatest differences between posterior cortical atrophy and typical Alzheimer's disease were seen in saccadic performance. Patients with posterior cortical atrophy made significantly shorter saccades especially for distant targets. They also exhibited a significant exacerbation of the normal gap/overlap effect, consistent with 'sticky fixation'. Time to reach saccadic targets was significantly associated with parietal and occipital cortical thickness measures. On fixation stability tasks, patients with typical Alzheimer's disease showed more square wave jerks whose frequency was associated with lower cerebellar grey matter volume, while patients with posterior cortical atrophy showed large saccadic intrusions whose frequency correlated significantly with generalized reductions in cortical thickness. Patients with both posterior cortical atrophy and typical Alzheimer's disease showed lower gain in smooth pursuit compared to controls. The current study establishes that eye movement abnormalities are near-ubiquitous in posterior cortical atrophy, and highlights multiple aspects of saccadic performance which distinguish posterior cortical atrophy from typical Alzheimer's disease. We suggest the posterior cortical atrophy oculomotor profile (e.g. exacerbation of the saccadic gap/overlap effect, preserved saccadic velocity) reflects weak input from degraded occipito-parietal spatial representations of stimulus location into a superior collicular spatial map for eye movement regulation. This may indicate greater impairment of identification of oculomotor targets rather than generation of oculomotor movements. The results highlight the critical role of spatial attention and object identification but also precise stimulus localization in explaining the complex real world perception deficits observed in posterior cortical atrophy and many other patients with dementia-related visual impairment. PMID:25895507

  12. Abnormalities of fixation, saccade and pursuit in posterior cortical atrophy

    PubMed Central

    Kaski, Diego; Yong, Keir X. X.; Paterson, Ross W.; Slattery, Catherine F.; Ryan, Natalie S.; Schott, Jonathan M.; Crutch, Sebastian J.

    2015-01-01

    The clinico-neuroradiological syndrome posterior cortical atrophy is the cardinal visual dementia and most common atypical Alzheimers disease phenotype, offering insights into mechanisms underlying clinical heterogeneity, pathological propagation and basic visual phenomena (e.g. visual crowding). Given the extensive attention paid to patients (higher order) perceptual function, it is surprising that there have been no systematic analyses of basic oculomotor function in this population. Here 20 patients with posterior cortical atrophy, 17 patients with typical Alzheimers disease and 22 healthy controls completed tests of fixation, saccade (including fixation/target gap and overlap conditions) and smooth pursuit eye movements using an infrared pupil-tracking system. Participants underwent detailed neuropsychological and neurological examinations, with a proportion also undertaking brain imaging and analysis of molecular pathology. In contrast to informal clinical evaluations of oculomotor dysfunction frequency (previous studies: 38%, current clinical examination: 33%), detailed eyetracking investigations revealed eye movement abnormalities in 80% of patients with posterior cortical atrophy (compared to 17% typical Alzheimers disease, 5% controls). The greatest differences between posterior cortical atrophy and typical Alzheimers disease were seen in saccadic performance. Patients with posterior cortical atrophy made significantly shorter saccades especially for distant targets. They also exhibited a significant exacerbation of the normal gap/overlap effect, consistent with sticky fixation. Time to reach saccadic targets was significantly associated with parietal and occipital cortical thickness measures. On fixation stability tasks, patients with typical Alzheimers disease showed more square wave jerks whose frequency was associated with lower cerebellar grey matter volume, while patients with posterior cortical atrophy showed large saccadic intrusions whose frequency correlated significantly with generalized reductions in cortical thickness. Patients with both posterior cortical atrophy and typical Alzheimers disease showed lower gain in smooth pursuit compared to controls. The current study establishes that eye movement abnormalities are near-ubiquitous in posterior cortical atrophy, and highlights multiple aspects of saccadic performance which distinguish posterior cortical atrophy from typical Alzheimers disease. We suggest the posterior cortical atrophy oculomotor profile (e.g. exacerbation of the saccadic gap/overlap effect, preserved saccadic velocity) reflects weak input from degraded occipito-parietal spatial representations of stimulus location into a superior collicular spatial map for eye movement regulation. This may indicate greater impairment of identification of oculomotor targets rather than generation of oculomotor movements. The results highlight the critical role of spatial attention and object identification but also precise stimulus localization in explaining the complex real world perception deficits observed in posterior cortical atrophy and many other patients with dementia-related visual impairment. PMID:25895507

  13. Posterior partially edentulous jaws, planning a rehabilitation with dental implants

    PubMed Central

    Monteiro, Douglas R; Silva, Emily V F; Pellizzer, Eduardo P; Filho, Osvaldo Magro; Goiato, Marcelo C

    2015-01-01

    AIM: To discuss important characteristics of the use of dental implants in posterior quadrants and the rehabilitation planning. METHODS: An electronic search of English articles was conducted on MEDLINE (PubMed) from 1990 up to the period of March 2014. The key terms were dental implants and posterior jaws, dental implants/treatment planning and posterior maxilla, and dental implants/treatment planning and posterior mandible. No exclusion criteria were used for the initial search. Clinical trials, randomized and non randomized studies, classical and comparative studies, multicenter studies, in vitro and in vivo studies, case reports, longitudinal studies and reviews of the literature were included in this review. RESULTS: One hundred and fifty-two articles met the inclusion criteria of treatment planning of dental implants in posterior jaw and were read in their entirety. The selected articles were categorized with respect to their context on space for restoration, anatomic considerations (bone quantity and density), radiographic techniques, implant selection (number, position, diameter and surface), tilted and pterygoid implants, short implants, occlusal considerations, and success rates of implants placed in the posterior region. The results derived from the review process were described under several different topic headings to give readers a clear overview of the literature. In general, it was observed that the use of dental implants in posterior region requires a careful treatment plan. It is important that the practitioner has knowledge about the theme to evaluate the treatment parameters. CONCLUSION: The use of implants to restore the posterior arch presents many challenges and requires a detailed treatment planning. PMID:25610852

  14. Cementoblastoma of posterior maxilla involving the maxillary sinus

    PubMed Central

    Dadhich, Anuj S.; Nilesh, Kumar

    2015-01-01

    Cementoblastoma is a rare neoplasm, representing <1% of all odontogenic tumors. It usually occurs in the posterior mandible and is associated with roots of a mandibular first molar or second premolar. This paper presents a rare case of cementoblastoma in the maxillary posterior region involving the maxillary sinus, in a young female patient. The clinical, radiological, and histopathological features of the lesion are discussed along with a review of previously reported cases in the literature. PMID:26389052

  15. Erupted complex odontoma of the posterior maxilla: A rarity

    PubMed Central

    Verma, Sonika; Arul, A. Sri Kennath J.; Arul, A. Sri Sennath J.; Chitra, S.

    2015-01-01

    Complex odontomas, hamartomas of aborted tooth development, mainly occur in posterior part of the mandible and rarely erupt into the oral cavity. The spontaneous eruption may be associated with pain, inflammation of adjacent soft tissues or recurrent infection. The present case of complex odontoma is of particular interest due to its apparent eruption in the maxillary posterior segment, its association with agenesis of the second molar and impacted third molar; with the lesion being completely asymptomatic. PMID:26604611

  16. Erupted complex odontoma of the posterior maxilla: A rarity.

    PubMed

    Verma, Sonika; Arul, A Sri Kennath J; Arul, A Sri Sennath J; Chitra, S

    2015-08-01

    Complex odontomas, hamartomas of aborted tooth development, mainly occur in posterior part of the mandible and rarely erupt into the oral cavity. The spontaneous eruption may be associated with pain, inflammation of adjacent soft tissues or recurrent infection. The present case of complex odontoma is of particular interest due to its apparent eruption in the maxillary posterior segment, its association with agenesis of the second molar and impacted third molar; with the lesion being completely asymptomatic. PMID:26604611

  17. A rare case of traumatic posterior phacocele with retinal detachment

    PubMed Central

    Sindal, Manavi D; Mourya, Deepesh

    2016-01-01

    Dislocation of crystalline lens into the anterior subconjunctival or subtenon's space is a rare but known complication of blunt trauma. Dislocation into the posterior subtenon's space is even rarer and can be associated with a complication such as occult scleral tear and retinal detachment. We report a case of traumatic posterior subtenon's dislocation of crystalline lens after blunt trauma and its successful surgical management. PMID:26953031

  18. Probability for Weather and Climate

    NASA Astrophysics Data System (ADS)

    Smith, L. A.

    2013-12-01

    Over the last 60 years, the availability of large-scale electronic computers has stimulated rapid and significant advances both in meteorology and in our understanding of the Earth System as a whole. The speed of these advances was due, in large part, to the sudden ability to explore nonlinear systems of equations. The computer allows the meteorologist to carry a physical argument to its conclusion; the time scales of weather phenomena then allow the refinement of physical theory, numerical approximation or both in light of new observations. Prior to this extension, as Charney noted, the practicing meteorologist could ignore the results of theory with good conscience. Today, neither the practicing meteorologist nor the practicing climatologist can do so, but to what extent, and in what contexts, should they place the insights of theory above quantitative simulation? And in what circumstances can one confidently estimate the probability of events in the world from model-based simulations? Despite solid advances of theory and insight made possible by the computer, the fidelity of our models of climate differs in kind from the fidelity of models of weather. While all prediction is extrapolation in time, weather resembles interpolation in state space, while climate change is fundamentally an extrapolation. The trichotomy of simulation, observation and theory which has proven essential in meteorology will remain incomplete in climate science. Operationally, the roles of probability, indeed the kinds of probability one has access too, are different in operational weather forecasting and climate services. Significant barriers to forming probability forecasts (which can be used rationally as probabilities) are identified. Monte Carlo ensembles can explore sensitivity, diversity, and (sometimes) the likely impact of measurement uncertainty and structural model error. The aims of different ensemble strategies, and fundamental differences in ensemble design to support of decision making versus advance science, are noted. It is argued that, just as no point forecast is complete without an estimate of its accuracy, no model-based probability forecast is complete without an estimate of its own irrelevance. The same nonlinearities that made the electronic computer so valuable links the selection and assimilation of observations, the formation of ensembles, the evolution of models, the casting of model simulations back into observables, and the presentation of this information to those who use it to take action or to advance science. Timescales of interest exceed the lifetime of a climate model and the career of a climate scientist, disarming the trichotomy that lead to swift advances in weather forecasting. Providing credible, informative climate services is a more difficult task. In this context, the value of comparing the forecasts of simulation models not only with each other but also with the performance of simple empirical models, whenever possible, is stressed. The credibility of meteorology is based on its ability to forecast and explain the weather. The credibility of climatology will always be based on flimsier stuff. Solid insights of climate science may be obscured if the severe limits on our ability to see the details of the future even probabilistically are not communicated clearly.

  19. Computational modelling of mobile bearing TKA anterior-posterior dislocation.

    PubMed

    Müller, J H; Zakaria, T; van der Merwe, W; D'Angelo, F

    2016-04-01

    Anterior-posterior stability in an unconstrained mobile-bearing total knee arthroplasty (TKA) and one with rotational constraints is compared in a computational model based on an ASTM test. Both TKA designs dislocate at loads greater than reported maximum in vivo forces. The posterior drawer forces (mean: 3027 N vs. 1817 N) needed to induce subluxation increase with a greater anterior jump distance (12 mm vs. 7 mm; refers to the vertical height of the anterior or posterior border of the tibial insert's articulating surface). The posterior jump distance for both tested TKA differed by 1.5 mm and had minimal effect on the magnitude of the anterior drawer forces at dislocation in mid-flexion (unconstrained vs. constrained: 445 N vs. 412 N). The unconstrained insert dislocated by means of spin-out whereas in the constrained TKA the femur dislocated from the bearing during posterior drawer and the bearing from the baseplate during anterior drawer. MCL function is an important consideration during ligament balancing since a ± 10% variation in MCL tension affects dislocation forces by ± 20%. The simulation platform provided the means to investigate TKA designs in terms of anterior-posterior stability as a function of knee flexion, collateral ligament function and mechanical morphology. PMID:26047039

  20. Optimizing tooth form with direct posterior composite restorations.

    PubMed

    Raghu, Ramya; Srinivasan, Raghu

    2011-10-01

    Advances in material sciences and technology have provided today's clinicians the strategies to transform the mechanistic approach of operative dentistry into a biologic philosophy. In the last three decades, composite resins have gone from being just an esthetically pleasing way of restoring Class III and Class IV cavities to become the universal material for both anterior and posterior situations as they closely mimic the natural esthetics while restoring the form of the human dentition. In order to enhance their success, clinicians have to rethink their protocol instead of applying the same restorative concepts and principles practiced with metallic restorations. Paralleling the evolution of posterior composite resin materials, cavity designs, restorative techniques and armamentarium have also developed rapidly to successfully employ composite resins in Class II situations. Most of the earlier problems with posterior composites such as poor wear resistance, polymerization shrinkage, postoperative sensitivity, predictable bonding to dentin, etc., have been overcome to a major extent. However, the clinically relevant aspect of achieving tight contacts in Class II situations has challenged clinicians the most. This paper reviews the evolution of techniques and recent developments in achieving predictable contacts with posterior composites. A Medline search was performed for articles on "direct posterior composite contacts." The keywords used were "contacts and contours of posterior composites." The reference list of each article was manually checked for additional articles of relevance. PMID:22144797

  1. The Black Hole Formation Probability

    NASA Astrophysics Data System (ADS)

    Clausen, Drew R.; Piro, Anthony; Ott, Christian D.

    2015-01-01

    A longstanding question in stellar evolution is which massive stars produce black holes (BHs) rather than neutron stars (NSs) upon death. It has been common practice to assume that a given zero-age main sequence (ZAMS) mass star (and perhaps a given metallicity) simply produces either an NS or a BH, but this fails to account for a myriad of other variables that may effect this outcome, such as spin, binarity, or even stochastic differences in the stellar structure near core collapse. We argue that instead a probabilistic description of NS versus BH formation may be better suited to account for the current uncertainties in understanding how massive stars die. Using the observed BH mass distribution from Galactic X-ray binaries, we investigate the probability that a star will make a BH as a function of its ZAMS mass. Although the shape of the black hole formation probability function is poorly constrained by current measurements, we believe that this framework is an important new step toward better understanding BH formation. We also consider some of the implications of this probability distribution, from its impact on the chemical enrichment from massive stars, to its connection with the structure of the core at the time of collapse, to the birth kicks that black holes receive. A probabilistic description of BH formation will be a useful input for future population synthesis studies that are interested in the formation of X-ray binaries, the nature and event rate of gravitational wave sources, and answering questions about chemical enrichment.

  2. Probability of Detection Demonstration Transferability

    NASA Technical Reports Server (NTRS)

    Parker, Bradford H.

    2008-01-01

    The ongoing Mars Science Laboratory (MSL) Propellant Tank Penetrant Nondestructive Evaluation (NDE) Probability of Detection (POD) Assessment (NESC activity) has surfaced several issues associated with liquid penetrant POD demonstration testing. This presentation lists factors that may influence the transferability of POD demonstration tests. Initial testing will address the liquid penetrant inspection technique. Some of the factors to be considered in this task are crack aspect ratio, the extent of the crack opening, the material and the distance between the inspection surface and the inspector's eye.

  3. On the probability distributions of ellipticity

    NASA Astrophysics Data System (ADS)

    Viola, M.; Kitching, T. D.; Joachimi, B.

    2014-04-01

    In this paper we derive an exact full expression for the 2D probability distribution of the ellipticity of an object measured from data, only assuming Gaussian noise in pixel values. This is a generalization of the probability distribution for the ratio of single random variables, that is well known, to the multivariate case. This expression is derived within the context of the measurement of weak gravitational lensing from noisy galaxy images. We find that the third flattening, or ɛ-ellipticity, has a biased maximum likelihood but an unbiased mean; and that the third eccentricity, or normalized polarization χ, has both a biased maximum likelihood and a biased mean. The very fact that the bias in the ellipticity is itself a function of the ellipticity requires an accurate knowledge of the intrinsic ellipticity distribution of the galaxies in order to properly calibrate shear measurements. We use this expression to explore strategies for calibration of biases caused by measurement processes in weak gravitational lensing. We find that upcoming weak-lensing surveys like KiDS or DES require calibration fields of the order of several square degrees and 1.2 mag deeper than the wide survey in order to correct for the noise bias. Future surveys like Euclid will require calibration fields of order 40 square degree and several magnitude deeper than the wide survey. We also investigate the use of the Stokes parameters to estimate the shear as an alternative to the ellipticity. We find that they can provide unbiased shear estimates at the cost of a very large variance in the measurement. The PYTHON code used to compute the distributions presented in the paper and to perform the numerical calculations are available on request.

  4. Risk-sensitive decision-making in patients with posterior parietal and ventromedial prefrontal cortex injury.

    PubMed

    Studer, Bettina; Manes, Facundo; Humphreys, Glyn; Robbins, Trevor W; Clark, Luke

    2015-01-01

    Successful choice under risk requires the integration of information about outcome probabilities and values and implicates a brain network including the ventromedial prefrontal cortex (vmPFC) and posterior parietal cortex (pPAR). Damage to the vmPFC is linked to poor decision-making and increased risk-taking. Electrophysiological and neuroimaging data implicate the pPAR in the processing of reward probability during choice, but the causal contribution of this area has not been established. We compared patients with lesions to the pPAR (n = 13), vmPFC (n = 13), and healthy volunteers (n = 22) on the Roulette Betting Task, a measure of risk-sensitive decision-making. Both lesion groups were impaired in adjusting their bets to the probability of winning. This impairment was correlated with the extent of pPAR, but not vmPFC, damage. In addition, the vmPFC group chose higher bets than healthy controls overall, an effect that correlated with lesion volume in the medial orbitofrontal cortex. Both lesion groups earned fewer points than healthy controls. The groups did not differ on 2 tasks assessing probabilistic reasoning outside of a risk-reward context. Our results demonstrate the causal involvement of both the pPAR and vmPFC in risk-sensitive choice and indicate distinguishable roles of these areas in probability processing and risk appetite. PMID:23926113

  5. Lectures on probability and statistics

    SciTech Connect

    Yost, G.P.

    1984-09-01

    These notes are based on a set of statistics lectures delivered at Imperial College to the first-year postgraduate students in High Energy Physics. They are designed for the professional experimental scientist. We begin with the fundamentals of probability theory, in which one makes statements about the set of possible outcomes of an experiment, based upon a complete a priori understanding of the experiment. For example, in a roll of a set of (fair) dice, one understands a priori that any given side of each die is equally likely to turn up. From that, we can calculate the probability of any specified outcome. We finish with the inverse problem, statistics. Here, one begins with a set of actual data (e.g., the outcomes of a number of rolls of the dice), and attempts to make inferences about the state of nature which gave those data (e.g., the likelihood of seeing any given side of any given die turn up). This is a much more difficult problem, of course, and one's solutions often turn out to be unsatisfactory in one respect or another.

  6. Using Particle Imaging Velocimetry to Measure Anterior-Posterior Velocity Gradients in the Excised Canine Larynx Model

    PubMed Central

    Khosla, Sid; Murugappan, Shanmugam; Lakhamraju, Raghavaraju; Gutmark, Ephraim

    2008-01-01

    Objectives To quantify the anterior-posterior velocity gradient, we studied the velocity flow fields above the vocal folds in both the midcoronal and midsagittal planes. It was also our purpose to use these fields to deduce the mechanisms that cause the anterior-posterior gradient and to determine whether the vortical structures are highly 3-dimensional. Methods Using the particle imaging velocimetry method for 5 excised canine larynges. we obtained phase-averaged velocity fields in the midcoronal and midsagittal planes for 30 phases of phonation. The velocity fields were determined synchronously with the vocal fold motion recorded by high-speed videography. Results The results show that immediately above the folds, there is no significant anterior-posterior velocity gradient. However, as the flow travels downstream, the laryngeal jet tends to narrow in width and skew toward the anterior commissure. Vortices are seen at the anterior and posterior edges of the flow. Conclusions The downstream narrowing in the midsagittal plane is consistent with and is probably due to a phenomenon known as axis switching. Axis switching also involves vortices in the sagittal and coronal planes bending in the axial plane. This results in highly 3-dimensional, complex vortical structures. However, there is remarkable cyclic repeatability of these vortices during a phonation cycle. PMID:18357838

  7. Posterior Surgery Alone in the Treatment of Post-traumatic Kyphosis by Posterior Column Osteotomy, Spondylodesis, Instrumentation, and Vertebroplasty

    PubMed Central

    Hasankhani, Ebrahim Ghayem; Ebrahimzadeh, Mohamed Hosein; Kachooei, Amir Reza; Heidari, Hosein

    2013-01-01

    Study Design Retrospective study. Purpose To determine if posterior surgery alone can satisfactorily treat post-traumatic kyphosis (PTK). Overview of Literature One of the worst complications of vertebral fractures is PTK. The type of surgery and approach to treat a symptomatic and refractory PTK is a challenging issue in spinal surgery, and yet, there is no specific treatment algorithm. Methods From August 2003 to September 2010, we collected 26 cases (male to female ratio, 2.25; mean age, 31.9±9.7 years and follow-up period of 42.4±8.1 months) with PTK treated by posterior column osteotomy, spondylodesis, instrumentation and cement vertebroplasty in one stage posterior surgery. PTK angle, Oswestry Disability Index (ODI), visual analogue scale (VAS), and subjective satisfaction from surgery were used to determine the results. We used a student t test for analyzing the data before and after surgery. Results In our patients, T11 and L1 had the highest incidence of vertebral fractures. The results indicated that in PTK, ODI, and VAS were significantly improved this surgery. Solid fusion occurred in 96.2% of patients with 3.2°±2.1° loss of correction. A total of 84.6% of patients have satisfaction level of excellent and good. Conclusions Posterior surgery alone with posterior column osteotomy, vertebroplasty, posterior spinal fusion and instrumentation can effectively treat symptomatic PTK. PMID:24353841

  8. Estimating Second Order Probability Beliefs from Subjective Survival Data

    PubMed Central

    Hudomiet, Péter; Willis, Robert J.

    2013-01-01

    Based on subjective survival probability questions in the Health and Retirement Study (HRS), we use an econometric model to estimate the determinants of individual-level uncertainty about personal longevity. This model is built around the modal response hypothesis (MRH), a mathematical expression of the idea that survey responses of 0%, 50%, or 100% to probability questions indicate a high level of uncertainty about the relevant probability. We show that subjective survival expectations in 2002 line up very well with realized mortality of the HRS respondents between 2002 and 2010. We show that the MRH model performs better than typically used models in the literature of subjective probabilities. Our model gives more accurate estimates of low probability events and it is able to predict the unusually high fraction of focal 0%, 50%, and 100% answers observed in many data sets on subjective probabilities. We show that subjects place too much weight on parents’ age at death when forming expectations about their own longevity, whereas other covariates such as demographics, cognition, personality, subjective health, and health behavior are under weighted. We also find that less educated people, smokers, and women have less certain beliefs, and recent health shocks increase uncertainty about survival, too. PMID:24403866

  9. [Postoperative opacification of posterior chamber intraocular lenses - a review].

    PubMed

    Schmidbauer, J M; Werner, L; Apple, D J; Pandey, S K; Izak, A M; Trivedi, R H; Macky, T A; Auffarth, G U; Peng, Q; Arthur, S N; Escobar-Gomez, M; Ma, L; Vargas, L G

    2001-09-01

    Postoperative opacification of intraocular lenses (IOLs) is a very unpleasant complication for the ophthalmic surgeon and the patient. We report on our experiences with opacification of different foldable IOL designs and rigid poly (methyl methacrylate) (PMMA) posterior chamber lenses.1. Snowflake degeneration of PMMA IOLs: This condition is an unanticipated and surprising late postoperative finding 8 to 15 years after implantation. In our opinion, this complication is probably not related to the PMMA biomaterial itself, but rather it appears to represent a manufacturing problem that has affected a selected, albeit large number of lenses manufactured in the 1980s-mid 1990s.2. Degeneration of UV absorber material and calcium deposits within the optic of hydrophilic IOLs: Two years postoperatively degenerations of UV absorber material and calcium deposits within the optic of single piece hydrophilic acrylic lenses SC60B-OUV manufactured by MDR (Medical developmental research Inc. Clearwater FL, USA) can occur. Although the precise mechanism is not fully known, it was assumed that these opacifications are due to premature aging of the UV blocking agent incorporated in the lens biomaterial and calcification.3. Calcification on the surface of the Bausch & Lomb Hydroviewtrade mark IOLs: Twelve to 15 months postoperatively granular surface calcifications in Hydroviewtrade mark IOLs occured. The mechanism is not fully understood. According to Bausch and Lomb studies, part of the components of the packaging contained silicone, which may have come off the packaging onto the lens optic, where it then appears to be a catalyst for calcium precipitation. The manufacturer has correlated a change in packaging with the appearance of the opacification. The manufacturer now believes that this problem has been solved. However, final verification will require a careful 1 - 2 years clinical study.4. Glistenings in the hydrophobic acrylic AcrySoftrade mark IOLs: The time frame of glistenings in the AcrySoftrade mark IOLs is highly variable. It has been suggested that the occurrence of glistenings may be related to variations in the temperature of the lens just prior to and or during insertion into the eye. Formation of vacuoles may occur within the submersed acrylic polymer when there is a transient increase and then decrease in temperature during the surgical procedure. "Glistenings" may then subsequently form by ingress of anterior chamber fluid. Contrast sensitivity can been decreased in some patients, but clinically significant decrease of visual acuity has been rare. PMID:11590465

  10. Constrained Mathematics for Calculating Logical Safety and Reliability Probabilities with Uncertain Inputs

    SciTech Connect

    Cooper, D.K.; Cooper, J.A.; Ferson, S.

    1999-01-21

    Calculating safety and reliability probabilities with functions of uncertain variables can yield incorrect or misleading results if some precautions are not taken. One important consideration is the application of constrained mathematics for calculating probabilities for functions that contain repeated variables. This paper includes a description of the problem and develops a methodology for obtaining an accurate solution.

  11. Impact of MCNP unresolved resonance probability-table treatment on uranium and plutonium benchmarks

    SciTech Connect

    Mosteller, R.D.; Little, R.C.

    1998-12-31

    Versions of MCNP up through and including 4B have not accurately modeled neutron self-shielding effects in the unresolved resonance energy region. Recently, a probability-table treatment has been incorporated into a developmental version of MCNP. This paper presents MCNP results for a variety of uranium and plutonium critical benchmarks, calculated with and without the probability-table treatment.

  12. MSPI False Indication Probability Simulations

    SciTech Connect

    Dana Kelly; Kurt Vedros; Robert Youngblood

    2011-03-01

    This paper examines false indication probabilities in the context of the Mitigating System Performance Index (MSPI), in order to investigate the pros and cons of different approaches to resolving two coupled issues: (1) sensitivity to the prior distribution used in calculating the Bayesian-corrected unreliability contribution to the MSPI, and (2) whether (in a particular plant configuration) to model the fuel oil transfer pump (FOTP) as a separate component, or integrally to its emergency diesel generator (EDG). False indication probabilities were calculated for the following situations: (1) all component reliability parameters at their baseline values, so that the true indication is green, meaning that an indication of white or above would be false positive; (2) one or more components degraded to the extent that the true indication would be (mid) white, and “false” would be green (negative) or yellow (negative) or red (negative). In key respects, this was the approach taken in NUREG-1753. The prior distributions examined were the constrained noninformative (CNI) prior used currently by the MSPI, a mixture of conjugate priors, the Jeffreys noninformative prior, a nonconjugate log(istic)-normal prior, and the minimally informative prior investigated in (Kelly et al., 2010). The mid-white performance state was set at ?CDF = ?10 ? 10-6/yr. For each simulated time history, a check is made of whether the calculated ?CDF is above or below 10-6/yr. If the parameters were at their baseline values, and ?CDF > 10-6/yr, this is counted as a false positive. Conversely, if one or all of the parameters are set to values corresponding to ?CDF > 10-6/yr but that time history’s ?CDF < 10-6/yr, this is counted as a false negative indication. The false indication (positive or negative) probability is then estimated as the number of false positive or negative counts divided by the number of time histories (100,000). Results are presented for a set of base case parameter values, and three sensitivity cases in which the number of FOTP demands was reduced, along with the Birnbaum importance of the FOTP.

  13. Interoceptive awareness changes the posterior insula functional connectivity profile.

    PubMed

    Kuehn, Esther; Mueller, Karsten; Lohmann, Gabriele; Schuetz-Bosbach, Simone

    2016-04-01

    Interoceptive awareness describes the ability to consciously perceive inner bodily signals, such as one's own heartbeat. The right anterior insula is assumed to mediate this ability. The role of the posterior insula, particularly posterior-to-anterior insula signal flows is less clear in this respect. We scanned 27 healthy people with either high or low interoceptive awareness using 3T fMRI, while they either monitored their own heartbeats, or external tones, respectively. We used a combination of network centrality and bivariate connectivity analyses to characterize changes in cortical signal flows between the posterior insula and the anterior insula during interoceptive awareness or exteroceptive awareness, respectively. We show that heartbeat monitoring was accompanied by reduced network centrality of the right posterior insula, and decreased functional connectivity strengths between the right posterior insula and the right mid and anterior insula. In addition, decreased signal flows between the right posterior insula and the bilateral anterior cingulate cortices, and the bilateral orbitofrontal cortices were observed during interoceptive awareness. Functional connectivity changes were only shown by people with high interoceptive awareness, and occurred specifically within the low-frequency range (i.e., <0.1 Hz). Both groups did not differ in their functional connectivity profiles during rest. Our results show for the first time that interoceptive awareness changes intra-insula signal flows in the low-frequency range. We speculate that the selective inhibition of slow signal progression along the posterior-to-anterior insula pathway during interoceptive awareness allows the salient and noiseless detection of one's own heartbeat. PMID:25613901

  14. Techniques for determining probabilities of geologic events and processes

    SciTech Connect

    Hunter, R.L. ); Mann, C.J. )

    1992-01-01

    The primary goal of this study has been to search out and evaluate existing quantitative methods for determining probabilities of events and processes in fields that seemed to be most closely related to the majority of the events considered important to long-term performance by earlier workers. These fields are thermomechanical behavior, mining engineering, hydrology, climatology, seismicity and tectonics, seismic hazard, volcanology, geochemistry, and resource exploration. Most of these events and processes can initiate, releases of the radioactive waste from a geologic repository, although geochemical processes primarily affect transport of wastes after release. The quantitative methods for determining probabilities identified here are those that have been reported in the literature, and some that could be used but have not been reported. Merits and limitations of each method have been described, and the current availability of databases adequate for determining accurate probabilities of events and processes has been appraised. A secondary goal has been to identify phenomena for which accurate probabilities cannot be determined now and areas of research that could materially improve our ability to make better probabilistic predictions in the immediate future.

  15. Techniques for determining probabilities of geologic events and processes

    SciTech Connect

    Hunter, R.L.; Mann, C.J.

    1992-10-01

    The primary goal of this study has been to search out and evaluate existing quantitative methods for determining probabilities of events and processes in fields that seemed to be most closely related to the majority of the events considered important to long-term performance by earlier workers. These fields are thermomechanical behavior, mining engineering, hydrology, climatology, seismicity and tectonics, seismic hazard, volcanology, geochemistry, and resource exploration. Most of these events and processes can initiate, releases of the radioactive waste from a geologic repository, although geochemical processes primarily affect transport of wastes after release. The quantitative methods for determining probabilities identified here are those that have been reported in the literature, and some that could be used but have not been reported. Merits and limitations of each method have been described, and the current availability of databases adequate for determining accurate probabilities of events and processes has been appraised. A secondary goal has been to identify phenomena for which accurate probabilities cannot be determined now and areas of research that could materially improve our ability to make better probabilistic predictions in the immediate future.

  16. Chaotic Hamiltonian systems: Survival probability

    NASA Astrophysics Data System (ADS)

    Avetisov, V. A.; Nechaev, S. K.

    2010-04-01

    We consider the dynamical system described by the area-preserving standard mapping. It is known for this system that P(t) , the normalized number of recurrences staying in some given domain of the phase space at time t (so-called survival probability) has the power-law asymptotics, P(t)t-? . We present new semiphenomenological arguments which enable us to map the dynamical system near the chaos border onto the effective ultrametric diffusion on the boundary of a treelike space with hierarchically organized transition rates. In the framework of our approach we have estimated the exponent ? as ?=ln2/ln(1+rg)?1.44 , where rg=(5-1)/2 is the critical rotation number.

  17. Delayed neutron emission probability measurements

    NASA Astrophysics Data System (ADS)

    Mathieu, L.; Serot, O.; Materna, T.; Bail, A.; Köster, U.; Faust, H.; Litaize, O.; Dupont, E.; Letourneau, A.; Panebianco, S.; Kratz, K. L.

    2009-10-01

    Some neutrons are emitted from fission fragments several seconds to several minutes after fission occurs. These delayed neutrons play a key role for the conduct and in safety aspects of nuclear reactors [1]. But the probabilities to emit such neutrons (Pn) are not well known. A summary of different database and compilation of Pn values is presented to show these discrepancies and uncertainties. Experiments are carried out at the Lohengrin mass spectrometer (at Institut Laue Langevin in Grenoble) and at the ISOLDE facility (CERN) in order to measure some Pn values. Two different techniques are used: either by using gamma-rays detection or neutron emission detection. These two techniques and some preliminary results are presented.

  18. Infarction of the unilateral posterior horn and lateral column of the spinal cord with sparing of posterior columns: demonstration by MRI.

    PubMed Central

    Kaneki, M; Inoue, K; Shimizu, T; Mannen, T

    1994-01-01

    Infarction of the spinal cord, particularly in the distribution of the posterior spinal arteries, is rare. Twenty seven cases of posterior spinal artery syndrome have been reported. In all cases, the posterior columns were affected, and in all but two, the lesions were bilateral. Here a 49-year-old woman is reported, who was affected with lumbar cord infarction in the distribution of the posterior spinal arteries, diagnosed by MRI and clinical presentation. This case is of special interest because of sparing of the posterior columns and the unilateral nature of the lesion, even though the infarction occurred in the distribution of the posterior spinal arteries. Images PMID:8201340

  19. Coding of Reward Probability and Risk by Single Neurons in Animals

    PubMed Central

    Burke, Christopher J.; Tobler, Philippe N.

    2011-01-01

    Probability and risk are important factors for value-based decision making and optimal foraging. In order to survive in an unpredictable world, organisms must be able to assess the probability and risk attached to future events and use this information to generate adaptive behavior. Recent studies in non-human primates and rats have shown that both probability and risk are processed in a distributed fashion throughout the brain at the level of single neurons. Reward probability has mainly been shown to be coded by phasic increases and decreases in firing rates in neurons in the basal ganglia, midbrain, parietal, and frontal cortex. Reward variance is represented in orbitofrontal and posterior cingulate cortex and through a sustained response of dopaminergic midbrain neurons. PMID:22013410

  20. Injuries to the posterior cruciate ligament of the knee.

    PubMed

    Kannus, P; Bergfeld, J; Järvinen, M; Johnson, R J; Pope, M; Renström, P; Yasuda, K

    1991-08-01

    The posterior cruciate ligament (PCL) is the strongest ligament about the knee and is approximately twice as strong as the anterior cruciate ligament. Its main function is to prevent the posterior dislocation of the tibia in relation to the femur, providing 95% of the strength to resist the tibial posterior displacement. Along with the anterior cruciate ligament (ACL) the PCL controls the passive 'screw home' mechanism of the knee in terminal knee extension. It also provides mechanical support for the collateral ligaments during valgus or varus stress of the knee. PCL ruptures are uncommon apparently due to its strong fibre structure. The most frequent injury mechanism in isolated PCL tears is a direct blow on the anterior tibia with the knee flexed thus driving the tibia posteriorly. Automobile accidents (in which the knee hits the dashboard) and soccer injuries (in which an athlete receives a blow to the anterior surface of the tibia during knee flexion) characteristically produce this type of injury. In other PCL injury mechanisms (hyperextension, hyperflexion or rotational injuries with associated valgum/varum stress), other knee structures are also often damaged. The most characteristic diagnostic finding in a knee with a PCL rupture is the 'posterior sag sign' meaning the apparent disappearance of the tibial tubercle in lateral inspection when the knee is flexed 90 degrees. This is due to gravity-assisted posterior displacement of the tibia in relation to the femur. A positive posterior drawer test performed at 90 degrees of flexion and a knee hyperextension sign are sensitive but nonspecific tests. False negative findings are frequent, especially in acute cases. If necessary, the clinical diagnosis of the PCL tear can be verified by magnetic resonance imaging, examination under anaesthesia, arthroscopy, or a combination of these modalities. If a PCL avulsion fragment has been dislocated, surgical treatment is recommended. In isolated, complete midsubstance tears of the PCL the majority of the recent studies recommend conservative treatment, since abnormal residual posterior laxity1 in most of these knees is consistent with functional stability and minimal symptoms. This has been the case even in athletes. In isolated PCL tears, the outcome seems to depend more on the muscular (quadriceps) status of the knee than on the amount of residual posterior laxity. Therefore, the conservative treatment protocol emphasises intensive quadriceps exercises, and only a short (under 2 weeks) immobilisation period followed by early controlled activities and early weightbearing.(ABSTRACT TRUNCATED AT 400 WORDS) PMID:1947532

  1. Features extraction in anterior and posterior cruciate ligaments analysis.

    PubMed

    Zarychta, P

    2015-12-01

    The main aim of this research is finding the feature vectors of the anterior and posterior cruciate ligaments (ACL and PCL). These feature vectors have to clearly define the ligaments structure and make it easier to diagnose them. Extraction of feature vectors is obtained by analysis of both anterior and posterior cruciate ligaments. This procedure is performed after the extraction process of both ligaments. In the first stage in order to reduce the area of analysis a region of interest including cruciate ligaments (CL) is outlined in order to reduce the area of analysis. In this case, the fuzzy C-means algorithm with median modification helping to reduce blurred edges has been implemented. After finding the region of interest (ROI), the fuzzy connectedness procedure is performed. This procedure permits to extract the anterior and posterior cruciate ligament structures. In the last stage, on the basis of the extracted anterior and posterior cruciate ligament structures, 3-dimensional models of the anterior and posterior cruciate ligament are built and the feature vectors created. This methodology has been implemented in MATLAB and tested on clinical T1-weighted magnetic resonance imaging (MRI) slices of the knee joint. The 3D display is based on the Visualization Toolkit (VTK). PMID:25825212

  2. Fetoscopic transuterine release of posterior urethral valves: a new technique.

    PubMed

    Clifton, Matthew S; Harrison, Michael R; Ball, Robert; Lee, Hanmin

    2008-01-01

    Fetal urinary tract obstruction with oligohydramnios produces pulmonary hypoplasia and renal dysplasia. Decompression of the obstructed urinary tract may restore amniotic fluid and allow lung growth, but transabdominal catheter shunt decompression is often inadequate and does not allow for cycling of the bladder, while open procedures cause significant maternal morbidity. Disruption of the anatomic obstruction, usually posterior urethral valves in a male fetus, would be ideal but has proven technically difficult. Here we describe a new technique of percutaneous fetal cystoscopy and disruption of posterior urethral valves, and the case report of our first application of this technique. We pre-sent a case of a 17-week male fetus with posterior urethral valves which underwent fetal cystoscopy for mechanical disruption of posterior urethral valves. This minimally invasive approach to disruption of posterior urethral valves in a fetus is a novel method for decompressing the urinary tract. The technique offers a minimal degree of maternal morbidity and, if instituted early enough, can restore amniotic fluid volume, avert fatal pulmonary hypoplasia and may preserve renal function. PMID:18033963

  3. A Simple Approach to Specimen Retrieval via Posterior Colpotomy Incision

    PubMed Central

    Menderes, Gulden; Tower, Amanda M.; Silasi, Dan-Arin; Azodi, Masoud

    2015-01-01

    Introduction: Posterior colpotomy incision for specimen retrieval is infrequently used in gynecologic laparoscopic surgery unless a concomitant hysterectomy is performed. We aim to describe a simple and unique technique for creating the colpotomy incision and to describe intraoperative and postoperative outcomes. Methods: Fifty patients underwent adnexal specimen retrieval through a posterior colpotomy incision. After devascularization and detachment of the adnexal specimen, the posterior cul-de-sac was visualized. The colpotomy incision was created by introducing a 12- or 15-mm laparoscopic trocar through the vagina into the posterior vaginal fornix under direct visualization. Specimens were placed into laparoscopic bags and removed through the vagina. The colpotomy incision was closed vaginally. Charts were reviewed for intraoperative and postoperative outcomes. Results: Twenty-nine women underwent adnexal surgery for an adnexal mass, 14 women underwent surgery for pelvic pain, and 7 women underwent adnexal surgery for primary prevention of malignancy. The specimens removed ranged in size from 2 to 16 cm (mean 5.7). The mean time patients were under anesthesia was 103 minutes (SD 57.3). There were no operative complications related to the colpotomy incision and no cases of postoperative vaginal cellulitis or pelvic infection were reported. Only 1 woman with a prior vaginal delivery reported dyspareunia postoperatively. Conclusion: This simple technique for posterior colpotomy incision can easily be added to the gynecologic surgeon's armamentarium and can be safely used for most women. PMID:25901107

  4. Flexor Digitorum Accessorius Longus: Importance of Posterior Ankle Endoscopy

    PubMed Central

    Batista, Jorge Pablo; del Vecchio, Jorge Javier; Golanó, Pau; Vega, Jordi

    2015-01-01

    Endoscopy for the posterior region of the ankle through two portals is becoming more widespread for the treatment of a large number of conditions which used to be treated with open surgery years ago. The tendon of the flexor hallucis longus (FHL) travels along an osteofibrous tunnel between the posterolateral and posteromedial tubercles of the talus. Chronic inflammation of this tendon may lead to painful stenosing tenosynovitis. The aim of this report is to describe two cases depicting an accessory tendon which is an anatomical variation of the flexor hallucis longus in patients with posterior friction syndrome due to posterior ankle impingement and associated with a posteromedial osteochondral lesion of the talus. The anatomical variation (FDAL) described was a finding during an endoscopy of the posterior region of the ankle, and we have spared it by sectioning the superior flexor retinaculum only. The accessory flexor digitorum longus is an anatomical variation and should be taken into account when performing an arthroscopy of the posterior region of the ankle. We recommend this treatment on this type of injury although we admit this does not make a definite conclusion. PMID:26060592

  5. Flexor Digitorum Accessorius Longus: Importance of Posterior Ankle Endoscopy.

    PubMed

    Batista, Jorge Pablo; Del Vecchio, Jorge Javier; Golanó, Pau; Vega, Jordi

    2015-01-01

    Endoscopy for the posterior region of the ankle through two portals is becoming more widespread for the treatment of a large number of conditions which used to be treated with open surgery years ago. The tendon of the flexor hallucis longus (FHL) travels along an osteofibrous tunnel between the posterolateral and posteromedial tubercles of the talus. Chronic inflammation of this tendon may lead to painful stenosing tenosynovitis. The aim of this report is to describe two cases depicting an accessory tendon which is an anatomical variation of the flexor hallucis longus in patients with posterior friction syndrome due to posterior ankle impingement and associated with a posteromedial osteochondral lesion of the talus. The anatomical variation (FDAL) described was a finding during an endoscopy of the posterior region of the ankle, and we have spared it by sectioning the superior flexor retinaculum only. The accessory flexor digitorum longus is an anatomical variation and should be taken into account when performing an arthroscopy of the posterior region of the ankle. We recommend this treatment on this type of injury although we admit this does not make a definite conclusion. PMID:26060592

  6. External Dacryocystorhinostomy with and Without Suturing the Posterior Mucosal Flaps

    PubMed Central

    Kaçaniku, Gazmend; Begolli, Ilir

    2014-01-01

    ABSTRACT Purpose: To evaluate the outcome of the external dacryocystorhinostomy with and without suturing the posterior mucosal flaps. Methods: This study included 106 patients with lacrimal drainage system disorders who underwent the external dacryocystorhinostomy. Fifty four patients (Group A) underwent external dacryocystorhinostomy with suturing anterior and posterior flaps of the lacrimal sac and nasal mucosa, and the results obtained were compared with those of another series of 52 patients (Group B) where dacryocystorhinostomy was performed with suturing only the anterior flaps, whereas posterior mucosal flaps were excised. Results: The success rate was evaluated by lacrimal patency to irrigation and relief of epiphora. Patency achieved in groups A and B was 94.4% and 96.2%, respectively. There was no statistically significant difference in success rate between the groups. Conclusion: Our study suggests that external dacryocystorhinostomy with suturing anterior and posterior flaps have no advantage over dacryocystorhinostomy with suturing only anterior flaps. Anastomosis by suturing only anterior flaps and excision of the posterior flaps is easier to perform and may improve the success rate of external dacryocystorhinostomy. PMID:24783915

  7. Ultrasound elasticity imaging of human posterior tibial tendon

    NASA Astrophysics Data System (ADS)

    Gao, Liang

    Posterior tibial tendon dysfunction (PTTD) is a common degenerative condition leading to a severe impairment of gait. There is currently no effective method to determine whether a patient with advanced PTTD would benefit from several months of bracing and physical therapy or ultimately require surgery. Tendon degeneration is closely associated with irreversible degradation of its collagen structure, leading to changes to its mechanical properties. If these properties could be monitored in vivo, it could be used to quantify the severity of tendonosis and help determine the appropriate treatment. Ultrasound elasticity imaging (UEI) is a real-time, noninvasive technique to objectively measure mechanical properties in soft tissue. It consists of acquiring a sequence of ultrasound frames and applying speckle tracking to estimate displacement and strain at each pixel. The goals of my dissertation were to 1) use acoustic simulations to investigate the performance of UEI during tendon deformation with different geometries; 2) develop and validate UEI as a potentially noninvasive technique for quantifying tendon mechanical properties in human cadaver experiments; 3) design a platform for UEI to measure mechanical properties of the PTT in vivo and determine whether there are detectable and quantifiable differences between healthy and diseased tendons. First, ultrasound simulations of tendon deformation were performed using an acoustic modeling program. The effects of different tendon geometries (cylinder and curved cylinder) on the performance of UEI were investigated. Modeling results indicated that UEI accurately estimated the strain in the cylinder geometry, but underestimated in the curved cylinder. The simulation also predicted that the out-of-the-plane motion of the PTT would cause a non-uniform strain pattern within incompressible homogeneous isotropic material. However, to average within a small region of interest determined by principal component analysis (PCA) would improve the estimation. Next, UEI was performed on five human cadaver feet mounted in a materials testing system (MTS) while the PTT was attached to a force actuator. A portable ultrasound scanner collected 2D data during loading cycles. Young's modulus was calculated from the strain, loading force and cross sectional area of the PTT. Average Young's modulus for the five tendons was (0.45+/-0.16GPa) using UEI. This was consistent with simultaneous measurements made by the MTS across the whole tendon (0.52+/-0.18GPa). We also calculated the scaling factor (0.12+/-0.01) between the load on the PTT and the inversion force at the forefoot, a measurable quantity in vivo. This study suggests that UEI could be a reliable in vivo technique for estimating the mechanical properties of the human PTT. Finally, we built a custom ankle inversion platform for in vivo imaging of human subjects (eight healthy volunteers and nine advanced PTTD patients). We found non-linear elastic properties of the PTTD, which could be quantified by the slope between the elastic modulus (E) and the inversion force (F). This slope (DeltaE/DeltaF), or Non-linear Elasticity Parameter (NEP), was significantly different for the two groups: 0.16+/-0.20 MPa/N for healthy tendons and 0.45+/-0.43 MPa/N for PTTD tendons. A receiver operating characteristic (ROC) curve revealed an area under the curve (AUC) of 0.83+/-0.07, which indicated that the classifier system is valid. In summary, the acoustic modeling, cadaveric studies, and in vivo experiments together demonstrated that UEI accurately quantifies tendon mechanical properties. As a valuable clinical tool, UEI also has the potential to help guide treatment decisions for advanced PTTD and other tendinopathies.

  8. 38 CFR 4.46 - Accurate measurement.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 38 Pensions, Bonuses, and Veterans' Relief 1 2014-07-01 2014-07-01 false Accurate measurement. 4... RATING DISABILITIES Disability Ratings The Musculoskeletal System 4.46 Accurate measurement. Accurate measurement of the length of stumps, excursion of joints, dimensions and location of scars with respect...

  9. 38 CFR 4.46 - Accurate measurement.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 38 Pensions, Bonuses, and Veterans' Relief 1 2013-07-01 2013-07-01 false Accurate measurement. 4... RATING DISABILITIES Disability Ratings The Musculoskeletal System 4.46 Accurate measurement. Accurate measurement of the length of stumps, excursion of joints, dimensions and location of scars with respect...

  10. 38 CFR 4.46 - Accurate measurement.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 38 Pensions, Bonuses, and Veterans' Relief 1 2012-07-01 2012-07-01 false Accurate measurement. 4... RATING DISABILITIES Disability Ratings The Musculoskeletal System 4.46 Accurate measurement. Accurate measurement of the length of stumps, excursion of joints, dimensions and location of scars with respect...

  11. 38 CFR 4.46 - Accurate measurement.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 38 Pensions, Bonuses, and Veterans' Relief 1 2010-07-01 2010-07-01 false Accurate measurement. 4... RATING DISABILITIES Disability Ratings The Musculoskeletal System § 4.46 Accurate measurement. Accurate measurement of the length of stumps, excursion of joints, dimensions and location of scars with respect...

  12. Comparative morphological remarks on the origin of the posterior femoral cutaneous nerve.

    PubMed

    Nakanishi, T; Kanno, Y; Kaneshige

    1976-01-01

    The origin and course of the posterior femoral cutaneous nerve were observed macroscopically in 38 Japanese adult cadavers which were dissected in the University of Hokkaido, Faculty of Medicine during the years 1971/72 and the results obtained were compared with those from some other mammals (rat, rabbit, dog and cat) and a number of bibliographical findings on the other animals. On the basis of the archetype of the pudendal plexus, the site of origin of the posterior femoral cutaneous nerve was divided into seven portions as follows: the sciatic nerve or inferior gluteal nerve (I) and its originating roots (RI), the bigeminal nerve (B) and its originating roots (RB), the part of junction of I and B (CIB), the pudendal nerve (P) and its originating roots (RP). According to the arising mode, the posterior femoral cutaneous nerve was calssified into seven types: Type A (the sciatic nerve type); the nerve arises from I and RI (horse, rat, bird, frog and salamander). Type B (the sciatic transitional type); the nerve arises from I, RI, CIB, RB and B (MAN AND MONKEY). Type C (the bigeminal nerve type); the nerve arises from CIB, RB and B (gorilla, chimpanzee, orangutan, cat and sphenodon). Type D (the pudendal transitional type); the nerve arises from CIB, RB, B, RP and P (dog). Type E (the pudendal nerve type); the nerve arises from RP and P (pig, cattle and rabbit). Type F (the mixed type); a mixture of A to E types. These various patterns in the posterior femoral cutaneous nerve may be explained by the comparative anatomical explanation on the limb medial rotation given in Braus' text-book of Anatomy (Bd. I, S. 273). From these descriptions it is reasonable to presume that the main trunk of the posterior femoral cutaneous nerve of the tetrapod below the Aves arises from the sciatic nerve and is analogous to the gluteal branches of mammals, with its main stem still retained in the pudendal nerve. If the cutaneous area supplied by the posterior femoral cutaneous nerve expands to the lateral border of the buttock in company with the lower limb medial rotation, the part between this area and that supplied by the pudendal nerve is enlarged. At first, these expanded areas are probably supplied by the branches of the pudendal nerve, which gradually become independent to become the main stem of the posterior femoral cutaneous nerve in mammals. This nerve seems, therefore, to be primarily a division of the pedendal nerve, and so in man has various types of arising patterns, A to E, in accordance with the scheme in the phylogeny. Those hypothetical changes are observed in the human sacral plexus, from which the cutaneous nerve arises with a fan-shaped overlapping. PMID:1275304

  13. Anomalous Posterior Intercostal Arterial Trunk Arising From the Abdominal Aorta.

    PubMed

    Jie, Bing; Yu, Dong; Jiang, Sen

    2016-04-01

    A common trunk of the ipsilateral posterior intercostal artery (PIA) arising from the thoracic aorta is usually an anatomical variation. However, a common trunk of bilateral posterior intercostal arterial trunk (PIAT) arising from the abdominal aorta is rare. It is important to recognize this anatomical variation of PIA when performing interventional radiological procedures. We present a rare case of an anomalous PIAT that originated from the abdominal aorta in a patient with hemoptysis caused by tuberculosis sequelae. Bilateral 4th to 11th PIAs arose from a common trunk and the trunk arising from the posterior aspect of the abdominal aorta at the level of T12/L1 intervertebral space. The pathological right 4th and 5th PIAs and bronchial arteries were embolized. Hemoptysis has been controlled for 3 months. PMID:26253781

  14. Arthroscopic Repair of a Posterior Bony Bankart Lesion.

    PubMed

    Poehling-Monaghan, Kirsten L; Krych, Aaron J; Dahm, Diane L

    2015-12-01

    Posterior bony defects of the glenoid rim, particularly those associated with instability, are often a frustrating challenge for arthroscopists because of the defects' inaccessibility from standard portals. This challenge is enhanced when the lesion is chronic and fibrous malunion of the fragment makes mobilization difficult. We present our technique for arthroscopic repair of the relatively uncommon chronic posterior bony Bankart lesion. By use of lateral positioning and a standard anterior viewing portal and posterior working portal, as well as a strategically placed posterolateral accessory portal, the lesion is first freed from its malreduced position and ultimately repaired using suture anchor fixation of the bony fragment along with its associated labrum directly to the remaining glenoid rim. This technique, facilitated by precise portal placement, results in satisfactory fragment reduction, appropriate capsular tension, and restoration of anatomy. PMID:26870644

  15. Endothelin: A novel peptide in the posterior pituitary system

    SciTech Connect

    Yoshizawa, Toshihiro; Kanazawa, Ichiro; Shinmi, Osamu; Kimura, Sadao; Yanagisawa, Masashi; Masaki, Tomoh; Uchiyama, Yasuo ); Giaid, A.; Gibson, S.J.; Polak, J.M. )

    1990-01-26

    Endothelin (ET), originally characterized as a 21-residue vasoconstrictor peptide from endothelial cells, is present in the porcine spinal cord and may act as a neuropeptide. Endothelin-like immunoreactivity has now been demonstrated by immunohistochemistry in the paraventricular and supraoptic nuclear neurons and their terminals in the posterior pituitary of the pig and the rat. The presence of ET in the porcine hypothalamus was confirmed by reversed-phase high-pressure liquid chromatography and radioimmunoassay. Moreover, in situ hybridization demonstrated ET messenger RNA in porcine paraventricular nuclear neurons. Endothelin-like immunoreactive products in the posterior pituitary of the rat were depleted by water deprivation, suggesting a release of ET under physiological conditions. These findings indicate that ET is synthesized in the posterior pituitary system and may be involved in neurosecretory functions.

  16. Arthroscopic Repair of a Posterior Bony Bankart Lesion

    PubMed Central

    Poehling-Monaghan, Kirsten L.; Krych, Aaron J.; Dahm, Diane L.

    2015-01-01

    Posterior bony defects of the glenoid rim, particularly those associated with instability, are often a frustrating challenge for arthroscopists because of the defects' inaccessibility from standard portals. This challenge is enhanced when the lesion is chronic and fibrous malunion of the fragment makes mobilization difficult. We present our technique for arthroscopic repair of the relatively uncommon chronic posterior bony Bankart lesion. By use of lateral positioning and a standard anterior viewing portal and posterior working portal, as well as a strategically placed posterolateral accessory portal, the lesion is first freed from its malreduced position and ultimately repaired using suture anchor fixation of the bony fragment along with its associated labrum directly to the remaining glenoid rim. This technique, facilitated by precise portal placement, results in satisfactory fragment reduction, appropriate capsular tension, and restoration of anatomy. PMID:26870644

  17. THORACOLUMBAR BURST FRACTURE: LOAD SHARING CLASSIFICATION AND POSTERIOR INSTRUMENTATION FAILURE

    PubMed Central

    Avanzi, Osmar; Landim, Elcio; Meves, Robert; Caffaro, Maria Fernanda; de Albuquerque Araujo Luyten, Felipe; Faria, Antonio Alexandre

    2015-01-01

    Objectives: To assess the relationship between sagittal collapse, posterior instrumentation failure and the McCormack classification among patients with thoracolumbar burst fractures who had undergone posterior arthrodesis more than one level above and one level below the fracture. Methods: This was a retrospective review based on the medical records and radiographs of 26 patients who underwent operations between January 1990 and December 2006. The parameters assessed were: worsening of kyphosis (Cobb), neurological dysfunction (Frankel) and failure of surgical treatment (implant breakage or loosening). Results: No relationship was found between sagittal collapse and the scoring in the McCormack classification (r = 0.221; P = 0.322). There was also no relationship between failure of the posterior implant and the scoring in this classification (p = 0.85). Conclusion: Our findings suggest that this classification is not applicable to patients who underwent arthrodesis more than one level above and one level below the fracture. PMID:27022547

  18. Quantification of Posterior Globe Flattening: Methodology Development and Validationc

    NASA Technical Reports Server (NTRS)

    Lumpkins, S. B.; Garcia, K. M.; Sargsyan, A. E.; Hamilton, D. R.; Berggren, M. D.; Antonsen, E.; Ebert, D.

    2011-01-01

    Microgravity exposure affects visual acuity in a subset of astronauts, and mechanisms may include structural changes in the posterior globe and orbit. Particularly, posterior globe flattening has been implicated in several astronauts. This phenomenon is known to affect some terrestrial patient populations, and has been shown to be associated with intracranial hypertension. It is commonly assessed by magnetic resonance imaging (MRI), computed tomography (CT), or B-mode ultrasound (US), without consistent objective criteria. NASA uses a semi-quantitative scale of 0-3 as part of eye/orbit MRI and US analysis for occupational monitoring purposes. The goal of this study was to initiate development of an objective quantification methodology for posterior globe flattening.

  19. Quantification of Posterior Globe Flattening: Methodology Development and Validation

    NASA Technical Reports Server (NTRS)

    Lumpkins, Sarah B.; Garcia, Kathleen M.; Sargsyan, Ashot E.; Hamilton, Douglas R.; Berggren, Michael D.; Ebert, Douglas

    2012-01-01

    Microgravity exposure affects visual acuity in a subset of astronauts and mechanisms may include structural changes in the posterior globe and orbit. Particularly, posterior globe flattening has been implicated in the eyes of several astronauts. This phenomenon is known to affect some terrestrial patient populations and has been shown to be associated with intracranial hypertension. It is commonly assessed by magnetic resonance imaging (MRI), computed tomography (CT) or B-mode Ultrasound (US), without consistent objective criteria. NASA uses a semiquantitative scale of 0-3 as part of eye/orbit MRI and US analysis for occupational monitoring purposes. The goal of this study was ot initiate development of an objective quantification methodology to monitor small changes in posterior globe flattening.

  20. [Posterior segment changes in microphthalmic eyes: case report].

    PubMed

    Novelli, Fernando José De; Nóbrega, Mário Junqueira; Rosa, Evandro Luis; Bortolotto, Cristina Martins Faria; Kuntz, Joyce

    2009-01-01

    Microphthalmos is a developmental ocular disorder defined as a small eyeball. The condition can be associated with abnormalities of anterior and posterior segments. The most common anterior characteristics include corneal opacities, angle-closure and a shallow anterior chamber and cataract. The main findings of posterior segment are uveal effusion, retinal folds, abnormalities of macular capillar vascularization, absence of foveal depression and peripheral retinoschisis. Three patients with microphthalmos were assisted and their OCT features of posterior segment were analyzed. The first case had uveal effusion syndrome, choroidal and retinal detachment treated with parcial sclerectomy at the four quadrants. The other case presented with neurosensory retinal fold at fovea and papillomacular area in both eyes without involvement of retinal pigment epithelium layer and choriocapillaris. The third patient showed absence of foveal depression. The main diferencial diagnosis for this condition is foveal hypoplasia. PMID:20027413

  1. Probability distributions of turbulent energy.

    PubMed

    Momeni, Mahdi; Müller, Wolf-Christian

    2008-05-01

    Probability density functions (PDFs) of scale-dependent energy fluctuations, P[deltaE(l)] , are studied in high-resolution direct numerical simulations of Navier-Stokes and incompressible magnetohydrodynamic (MHD) turbulence. MHD flows with and without a strong mean magnetic field are considered. For all three systems it is found that the PDFs of inertial range energy fluctuations exhibit self-similarity and monoscaling in agreement with recent solar-wind measurements [Hnat, Geophys. Res. Lett. 29, 86 (2002)]. Furthermore, the energy PDFs exhibit similarity over all scales of the turbulent system showing no substantial qualitative change of shape as the scale of the fluctuations varies. This is in contrast to the well-known behavior of PDFs of turbulent velocity fluctuations. In all three cases under consideration the P[deltaE(l)] resemble Lévy-type gamma distributions approximately Delta;{-1} exp(-|deltaE|/Delta)|deltaE|;{-gamma} The observed gamma distributions exhibit a scale-dependent width Delta(l) and a system-dependent gamma . The monoscaling property reflects the inertial-range scaling of the Elsässer-field fluctuations due to lacking Galilei invariance of deltaE . The appearance of Lévy distributions is made plausible by a simple model of energy transfer. PMID:18643170

  2. The posterior bone block procedure in posterior shoulder instability: a long-term follow-up study.

    PubMed

    Meuffels, D E; Schuit, H; van Biezen, F C; Reijman, M; Verhaar, J A N

    2010-05-01

    We present the long-term outcome, at a median of 18 years (12.8 to 23.5) of open posterior bone block stabilisation for recurrent posterior instability of the shoulder in a heterogenous group of 11 patients previously reported on in 2001 at a median follow-up of six years. We found that five (45%) would not have chosen the operation again, and that four (36%) had further posterior dislocation. Clinical outcome was significantly worse after 18 years than after six years of follow-up (median Rowe score of 60 versus 90 (p = 0.027)). The median Western Ontario Shoulder Index was 60% (37% to 100%) at 18 years' follow-up, which is a moderate score. At the time of surgery four (36%) had glenohumeral radiological osteoarthritis, which was present in all after 18 years. This study showed poor long-term results of the posterior bone block procedure for posterior instability and a high rate of glenohumeral osteoarthritis although three patients with post-traumatic instability were pleased with the result of their operations. PMID:20436001

  3. Exploring the Overestimation of Conjunctive Probabilities

    PubMed Central

    Nilsson, Hkan; Rieskamp, Jrg; Jenny, Mirjam A.

    2013-01-01

    People often overestimate probabilities of conjunctive events. The authors explored whether the accuracy of conjunctive probability estimates can be improved by increased experience with relevant constituent events and by using memory aids. The first experiment showed that increased experience with constituent events increased the correlation between the estimated and the objective conjunctive probabilities, but that it did not reduce overestimation of conjunctive probabilities. The second experiment showed that reducing cognitive load with memory aids for the constituent probabilities led to improved estimates of the conjunctive probabilities and to decreased overestimation of conjunctive probabilities. To explain the cognitive process underlying peoples probability estimates, the configural weighted average model was tested against the normative multiplicative model. The configural weighted average model generates conjunctive probabilities that systematically overestimate objective probabilities although the generated probabilities still correlate strongly with the objective probabilities. For the majority of participants this model was better than the multiplicative model in predicting the probability estimates. However, when memory aids were provided, the predictive accuracy of the multiplicative model increased. In sum, memory tools can improve peoples conjunctive probability estimates. PMID:23460026

  4. Complications associated with posterior approaches in minimally invasive spine decompression.

    PubMed

    Stadler, James A; Wong, Albert P; Graham, Randall B; Liu, John C

    2014-04-01

    Posterior approaches for decompression in minimally invasive spine surgery are increasingly used for a wide range of pathology. Surgeons and patients must understand these risks in order to identify, manage, and ideally prevent complications. Technical intraoperative complications, recurrences and reoperations, infections, and medical complications associated with the surgery are considered for common posterior minimally invasive decompression procedures of the cervical and lumbar spine. Methods of possibly avoiding these complications are also discussed. This article then aggregates the relevant data to allow concise understanding of the complications associated with these procedures. PMID:24703443

  5. Surgical treatment of posterior nutcracker syndrome presented with hyperaldosteronism.

    PubMed

    Deser, Serkan Burc; Onem, Kadir; Demirag, Mustafa Kemal; Buyukalpelli, Recep

    2016-05-01

    Posterior nutcracker syndrome is caused by the compression of left renal vein between the abdominal aorta and the vertebral body. Most seen symptoms are haematuria, left flank pain, abdominal pain and varicocele. The nutcracker syndrome may lead to left renal vein thrombosis due to blood congestion within compression of the vessel. Both endovascular and open surgical interventions can relieve symptoms; however, traditional surgical repair is still considered as the gold standard. Here, we present the surgical treatment of a 36-year old female with complaints of hypertension, hyperaldosteronism and diagnosed with posterior nutcracker syndrome. PMID:26892192

  6. Posterior fusion of the subaxial cervical spine: indications and techniques.

    PubMed

    Liu, J K; Das, K

    2001-01-01

    The biomechanical stability of the subaxial cervical spine (C3-7) can be compromised by numerous pathological processes, and the restoration of stability may ultimately require fusion and placement of rigid internal fixation devices. A posterior fusion and stabilization procedure is often used to treat cervical instability secondary to traumatic injury, rheumatoid arthritis, ankylosing spondylitis, neoplastic disease, infections, and previous laminectomy. Numerous techniques and advances in spinal instrumentation have evolved over the last 30 years. The authors review the indications and the various methods for stabilizing and fusing the subaxial cervical spine via posterior approaches. PMID:16732634

  7. Spinal Hydatid as a Rare Cause of Posterior Mediastinal Lesion: Understanding Cervicothoracic Sign on Chest Radiography

    PubMed Central

    Aswani, Yashant; Hira, Priya

    2015-01-01

    Summary Background Location of an intrathoracic lesion on chest radiograph is facilitated by application of ‘silhouette sign’. This helps narrow down the differential diagnoses. The list of probable diagnoses reduces further on determination of the density of the lesion. A spinal hydatid presents as a fluid-density posterior mediastinal lesion on chest radiograph with destruction of the vertebral body and preservation of the disc space. Spinal hydatid is, however, rare. Case Report We describe a case of a 30-year-old female with gradual-onset paraperesis since six months. Chest radiograph was suggestive of a posterior mediastinal lesion with fluid density and destruction of D4 vertebra. MRI findings were consistent with spinal hydatid. The patient was started on perioperative benzimidazole therapy with resection of the hydatid cyst. The drug therapy was continued for six months post-operatively. Conclusions A chest radiograph helps localise the site and possible contents of the lesion. It also guides further investigations. MRI is the imaging modality of choice for spinal pathologies causing cord compression including spinal hydatid. Echinococcal involvement of the spine is a rarity but needs to be considered in the differential diagnoses for spinal causes of gradual-onset paraperesis. PMID:26692911

  8. A Catalog of Transit Timing Posterior Distributions for all Kepler Planet Candidate Transit Events

    NASA Astrophysics Data System (ADS)

    Montet, Benjamin Tyler; Becker, Juliette C.; Johnson, John Asher

    2015-12-01

    Kepler has ushered in a new era of planetary dynamics, enabling the detection of interactions between multiple planets in transiting systems for hundreds of systems. These interactions, observed as transit timing variations (TTVs), have been used to find non-transiting companions to transiting systems and to measure masses, eccentricities, and inclinations of transiting planets. Often, physical parameters are inferred by comparing the observed light curve to the result of a photodynamical model, a time-intensive process that often ignores the effects of correlated noise in the light curve. Catalogs of transit timing observations have previously neglected non-Gaussian uncertainties in the times of transit, uncertainties in the transit shape, and short cadence data. Here, I present a catalog of not only times of transit centers, but also posterior distributions on the time of transit for every planet candidate transit event in the Kepler data, developed through importance sampling of each transit. This catalog allows one to marginalize over uncertainties in the transit shape and incorporate short cadence data, the effects of correlated noise, and non-Gaussian posteriors. Our catalog will enable dynamical studies that reflect accurately the precision of Kepler and its limitations without requiring the computational power to model the light curve completely with every integration. I will also present our open-source N-body photodynamical modeling code, which integrates planetary and stellar orbits accounting for the effects of GR, tidal effects, and Doppler beaming.

  9. A Catalog of Transit Timing Posterior Distributions for all Kepler Planet Candidate Events

    NASA Astrophysics Data System (ADS)

    Montet, Benjamin Tyler; Becker, Juliette C.; Johnson, John

    2015-08-01

    Kepler has ushered in a new era of planetary dynamics, enabling the detection of interactions between multiple planets in transiting systems for hundreds of systems. These interactions, observed as transit timing variations (TTVs), have been used to find non-transiting companions to transiting systems and to measure masses, eccentricities, and inclinations of transiting planets. Often, physical parameters are inferred by comparing the observed light curve to the result of a photodynamical model, a time-intensive process that often ignores the effects of correlated noise in the light curve. Catalogs of transit timing observations have previously neglected non-Gaussian uncertainties in the times of transit, uncertainties in the transit shape, and short cadence data. Here, we present a catalog of not only times of transit centers, but also posterior distributions on the time of transit for every planet candidate transit event in the Kepler data, developed through importance sampling of each transit. This catalog allows us to marginalize over uncertainties in the transit shape and incorporate short cadence data, the effects of correlated noise, and non-Gaussian posteriors. Our catalog will enable dynamical studies that reflect accurately the precision of Kepler and its limitations without requiring the computational power to model the light curve completely with every integration.

  10. The Black Hole Formation Probability

    NASA Astrophysics Data System (ADS)

    Clausen, Drew; Piro, Anthony L.; Ott, Christian D.

    2015-02-01

    A longstanding question in stellar evolution is which massive stars produce black holes (BHs) rather than neutron stars (NSs) upon death. It has been common practice to assume that a given zero-age main sequence (ZAMS) mass star (and perhaps a given metallicity) simply produces either an NS or a BH, but this fails to account for a myriad of other variables that may effect this outcome, such as spin, binarity, or even stochastic differences in the stellar structure near core collapse. We argue that instead a probabilistic description of NS versus BH formation may be better suited to account for the current uncertainties in understanding how massive stars die. We present an initial exploration of the probability that a star will make a BH as a function of its ZAMS mass, P BH(M ZAMS). Although we find that it is difficult to derive a unique P BH(M ZAMS) using current measurements of both the BH mass distribution and the degree of chemical enrichment by massive stars, we demonstrate how P BH(M ZAMS) changes with these various observational and theoretical uncertainties. We anticipate that future studies of Galactic BHs and theoretical studies of core collapse will refine P BH(M ZAMS) and argue that this framework is an important new step toward better understanding BH formation. A probabilistic description of BH formation will be useful as input for future population synthesis studies that are interested in the formation of X-ray binaries, the nature and event rate of gravitational wave sources, and answering questions about chemical enrichment.

  11. THE BLACK HOLE FORMATION PROBABILITY

    SciTech Connect

    Clausen, Drew; Piro, Anthony L.; Ott, Christian D.

    2015-02-01

    A longstanding question in stellar evolution is which massive stars produce black holes (BHs) rather than neutron stars (NSs) upon death. It has been common practice to assume that a given zero-age main sequence (ZAMS) mass star (and perhaps a given metallicity) simply produces either an NS or a BH, but this fails to account for a myriad of other variables that may effect this outcome, such as spin, binarity, or even stochastic differences in the stellar structure near core collapse. We argue that instead a probabilistic description of NS versus BH formation may be better suited to account for the current uncertainties in understanding how massive stars die. We present an initial exploration of the probability that a star will make a BH as a function of its ZAMS mass, P {sub BH}(M {sub ZAMS}). Although we find that it is difficult to derive a unique P {sub BH}(M {sub ZAMS}) using current measurements of both the BH mass distribution and the degree of chemical enrichment by massive stars, we demonstrate how P {sub BH}(M {sub ZAMS}) changes with these various observational and theoretical uncertainties. We anticipate that future studies of Galactic BHs and theoretical studies of core collapse will refine P {sub BH}(M {sub ZAMS}) and argue that this framework is an important new step toward better understanding BH formation. A probabilistic description of BH formation will be useful as input for future population synthesis studies that are interested in the formation of X-ray binaries, the nature and event rate of gravitational wave sources, and answering questions about chemical enrichment.

  12. Posterior Trans-Dural Repair of Iatrogenic Spinal Cord Herniation after Resection of Ossification of Posterior Longitudinal Ligament

    PubMed Central

    Kim, Hong-Ki; Kim, Ki-Jeong; Jahng, Tae-Ahn; Kim, Hyun-Jib

    2016-01-01

    Iatrogenic spinal cord herniation is a rare complication following spinal surgery. We introduce a posterior trans-dural repair technique used in a case of thoracic spinal cord herniation through a ventral dural defect following resection of ossification of the posterior longitudinal ligament (OPLL) in the cervicothoracic spine. A 51-year-old female was suffering from paraplegia after laminectomy alone for cervicothoracic OPLL. Magnetic resonance imaging revealed a severely compressed spinal cord with pseudomeningocele identified postoperatively. Cerebrospinal fluid leak and iatrogenic spinal cord herniation persisted despite several operations with duroplasty and sealing agent. Finally, the problems were treated by repair of the ventral dural defect with posterior trans-dural duroplasty. Several months after surgery, the patient could walk independently. This surgical technique can be applied to treat ventral dural defect and spinal cord herniation. PMID:27114779

  13. Neuronal representation of saccadic error in macaque posterior parietal cortex (PPC).

    PubMed

    Zhou, Yang; Liu, Yining; Lu, Haidong; Wu, Si; Zhang, Mingsha

    2016-01-01

    Motor control, motor learning, self-recognition, and spatial perception all critically depend on the comparison of motor intention to the actually executed movement. Despite our knowledge that the brainstem-cerebellum plays an important role in motor error detection and motor learning, the involvement of neocortex remains largely unclear. Here, we report the neuronal computation and representation of saccadic error in macaque posterior parietal cortex (PPC). Neurons with persistent pre- and post-saccadic response (PPS) represent the intended end-position of saccade; neurons with late post-saccadic response (LPS) represent the actual end-position of saccade. Remarkably, after the arrival of the LPS signal, the PPS neurons' activity becomes highly correlated with the discrepancy between intended and actual end-position, and with the probability of making secondary (corrective) saccades. Thus, this neuronal computation might underlie the formation of saccadic error signals in PPC for speeding up saccadic learning and leading the occurrence of secondary saccade. PMID:27097103

  14. Patellar clunk in total knee arthroplasty using modified Sigma posterior stabilized femoral component

    PubMed Central

    Rajshekhar, K.T.; Kumar, M.N.; Venugopal, P.; Chandy, Thomas

    2014-01-01

    Aim The purpose of this study was to evaluate the efficacy of the enhanced PS femoral component design released in 2008 by DePuy. The patellar clunk syndrome has been reported in a significant number of patients following total knee arthroplasty. Design modifications of the implant have been made to reduce the incidence of the patellar clunk, especially in the posterior substituted designs. Methods 130 total knee replacements performed using the enhanced PS femoral components were followed-up with clinical and radiographic evaluations. Results Patellar clunk was seen in 3 of the 130 knees (2%). This is much less than the incidence of patellar clunk reported until now. Conclusions Removal of the sharp ridge in the intercondylar groove in the newer implant seems to have been effective in reducing the incidence of the patellar clunk. It also indicates that the sharp ridge was the most probable cause of the clunk. PMID:25983500

  15. Application-dependent Probability Distributions for Offshore Wind Speeds

    NASA Astrophysics Data System (ADS)

    Morgan, E. C.; Lackner, M.; Vogel, R. M.; Baise, L. G.

    2010-12-01

    The higher wind speeds of the offshore environment make it an attractive setting for future wind farms. With sparser field measurements, the theoretical probability distribution of short-term wind speeds becomes more important in estimating values such as average power output and fatigue load. While previous studies typically compare the accuracy of probability distributions using R2, we show that validation based on this metric is not consistent with validation based on engineering parameters of interest, namely turbine power output and extreme wind speed. Thus, in order to make the most accurate estimates possible, the probability distribution that an engineer picks to characterize wind speeds should depend on the design parameter of interest. We introduce the Kappa and Wakeby probability distribution functions to wind speed modeling, and show that these two distributions, along with the Biweibull distribution, fit wind speed samples better than the more widely accepted Weibull and Rayleigh distributions based on R2. Additionally, out of the 14 probability distributions we examine, the Kappa and Wakeby give the most accurate and least biased estimates of turbine power output. The fact that the 2-parameter Lognormal distribution estimates extreme wind speeds (i.e. fits the upper tail of wind speed distributions) with least error indicates that not one single distribution performs satisfactorily for all applications. Our use of a large dataset composed of 178 buoys (totaling ~72 million 10-minute wind speed observations) makes these findings highly significant, both in terms of large sample size and broad geographical distribution across various wind regimes. Boxplots of R2 from the fit of each of the 14 distributions to the 178 boy wind speed samples. Distributions are ranked from left to right by ascending median R2, with the Biweibull having the closest median to 1.

  16. Clinical and Radiological Results of Microsurgical Posterior Lumbar Interbody Fusion and Decompression without Posterior Instrumentation for Lateral Recess Stenosis

    PubMed Central

    Şişman, Lokman; Türkmen, Faik; Efe, Duran; Pekince, Oğuzhan; Göncü, Recep Gani; Sever, Cem

    2015-01-01

    Study Design A single-center, retrospective patient review of clinical and radiological outcomes of microsurgical posterior lumbar interbody fusion and decompression, without posterior instrumentation, for the treatment of lateral recess stenosis. Purpose This study documented the clinical and radiological results of microsurgical posterior lumbar interbody fusion and decompression of the lateral recess using interbody cages without posterior instrumentation for the treatment of lateral recess stenosis. Overview of Literature Although microsurgery has some advantages, various complications have been reported following microsurgical decompression, including cage migration, pseudoarthrosis, neurologic deficits, and persistent pain. Methods A total of 34 patients (13 men, 21 women), with a mean age of 56.65±9.1 years (range, 40-77 years) confirmed spinal stability, and preoperative radiological findings of lateral recess stenosis, were included in the study. Interbody polyetheretherketone cages and auto grafts were used in all patients. Posterior instrumentation was not used because of limited resection of the posterior lumbar structures. Preoperative and postoperative radiographs, computed tomography scans, and magnetic resonance imaging were assessed and compared to images taken at the final follow-up. Functional recovery was also evaluated according to the Macnab criteria at the final follow-up. Results The average follow-up time was 35.05±8.65 months (range, 24-46 months). The clinical results, operative time, intraoperative blood loss, and duration of hospital stay were similar to previously published results; the fusion rate (85.2%) was decreased and the migration rate (5.8%) was increased, compared with prior reports. Conclusions Although microsurgery has some advantages, migration and pseudoarthrosis remain challenges to achieving adequate lumbar interbody fusion. PMID:26435789

  17. Failure of the Pipeline Embolization Device in Posterior Communicating Artery Aneurysms Associated with a Fetal Posterior Cerebral Artery

    PubMed Central

    Zanaty, Mario; Chalouhi, Nohra; Starke, Robert M.; Jabbour, Pascal; Ryken, Katherine O.; Bulsara, Ketan R.; Hasan, David

    2016-01-01

    The pipeline embolization device has emerged as an important endovascular option. This is in part due to safety, efficacy, and possibly the ability to shorten the operative time considerably. With this new technology, some limitations are emerging as experience accumulates. We report three cases of posterior communicating (PCOM) artery aneurysms associated with fetal posterior cerebral artery where pipeline embolization was unsuccessful in obliterating the aneurysms. PCOM artery aneurysms associated with a fetal PCA should be managed either by microsurgical clipping or coiling when feasible. PMID:27069709

  18. Posterior Hip Dislocation Associated with Posterior Wall Acetabular Fracture and Ipsilateral Intertrochantric Fracture: a Very Rare Case Report

    PubMed Central

    Yousefi, Ahmad; Ashraf, Hami; Mashhadinezhad, Ali; Birjandinejad, Ali

    2013-01-01

    Abstract Traumatic hip dislocations are common in high-energy motor vehicle accidents. We present a case of a 43-year old man who sustained posterior hip dislocation with posterior wall acetabular fracture and ipsilateral intertrochantric fracture following a motorcycle accident. Urgent open reduction and internal fixation of the hip fracture-dislocation and fixation of intertrochantric fracture with a dynamic hip screw were done. To our knowledge, such an injury has been rarely reported in the literature. Possible mechanisms of injury and operative procedures are discussed. Radiographic follow-up after eight months showed union. No major complications were observed in our patient. PMID:24350139

  19. The Probability Distribution for a Biased Spinner

    ERIC Educational Resources Information Center

    Foster, Colin

    2012-01-01

    This article advocates biased spinners as an engaging context for statistics students. Calculating the probability of a biased spinner landing on a particular side makes valuable connections between probability and other areas of mathematics. (Contains 2 figures and 1 table.)

  20. Research on probability distribution of port cargo throughput

    NASA Astrophysics Data System (ADS)

    Sun, Liang; Tan, De-Rong

    2008-03-01

    In order to more accurately examine developing trends in gross cargo throughput, we have modeled the probability distribution of cargo throughput. Gross cargo throughput is determined by the time spent by cargo ships in the port and the operating efficiency of handling equipment. Gross cargo throughput is the sum of all compound variables determining each aspect of cargo throughput for every cargo ship arriving at the port. Probability distribution was determined using the Wald equation. The results show that the variability of gross cargo throughput primarily depends on the different times required by different cargo ships arriving at the port. This model overcomes the shortcoming of previous models: inability to accurately determine the probability of a specific value of future gross cargo throughput. Our proposed model of cargo throughput depends on the relationship between time required by a cargo ship arriving at the port and the operational capacity of handling equipment at the port. At the same time, key factors affecting gross cargo throughput are analyzed. In order to test the efficiency of the model, the cargo volume of a port in Shandong Province was used as an example. In the case study the actual results matched our theoretical analysis.

  1. Cytoarchitecture and Probabilistic Maps of the Human Posterior Insular Cortex

    PubMed Central

    Eickhoff, Simon B.; Schleicher, Axel; Hoemke, Lars; Zilles, Karl; Amunts, Katrin

    2010-01-01

    The human posterior insula was shown to respond to a wide variety of stimulation paradigms (e.g. pain, somatosensory, or auditory processing) in functional imaging experiments. Although various anatomical maps of this region have been published over the last century, these schemes show variable results. Moreover, none can directly be integrated with functional imaging data. Hence, our current knowledge about the structurefunction relationships in this region remains limited. We therefore remapped the posterior part of the human insular cortex in 10 postmortem brains using an observer-independent approach. This analysis revealed the existence of 3 cytoarchitectonically distinct areas in the posterior insula. The examined brains were then 3D reconstructed and spatially normalized to the Montreal Neurological Institute single-subject template. Probabilistic maps for each area were calculated by superimposing the individual delineations, and a cytoarchitectonic summary map was computed to chart the regional architectonic organization. These maps can be used to identify the anatomical correlates of functional activations observed in neuroimaging studies and to understand the microstructural correlates of the functional segregation of the human posterior insula. PMID:19822572

  2. Suture Bridge Fixation Technique for Posterior Cruciate Ligament Avulsion Fracture

    PubMed Central

    Lee, Kwang Won; Lee, Gyu Sang; Choy, Won Sik

    2015-01-01

    We presented a surgical technique including a suture bridge technique with relatively small incision for the reduction and fixation of posterior ligament avulsion fractures. A suture anchor was used to hold the avulsed fragment and a knotless anchor was used to continuously compress the bony fragment into the fracture site, thereby maintaining reduction during healing. PMID:26640635

  3. Posterior Cortical Atrophy Presenting with Superior Arcuate Field Defect

    PubMed Central

    Wan, Sue Ling; Bukowska, Danuta M.; Ford, Stephen; Chen, Fred K.

    2015-01-01

    An 80-year-old female with reading difficulty presented with progressive arcuate field defect despite low intraocular pressure. Over a 5-year period, the field defect evolved into an incongruous homonymous hemianopia and the repeated neuroimaging revealed progressive posterior cortical atrophy. Further neuropsychiatric assessment demonstrated symptoms and signs consistent with Benson's syndrome. PMID:26417467

  4. Posterior crossbite and temporomandibular disorders (TMDs): need for orthodontic treatment?

    PubMed

    Thilander, Birgit; Bjerklin, Krister

    2012-12-01

    The aim of this work was to update the bibliography regarding the concept of 'temporomandibular disorder (TMD)' and 'posterior crossbite' and try to find out if there is any association between some special signs/symptoms of TMD and type of posterior crossbite. A literature search from 1970 to 2009, due to specified criterion, resulted in 14 publications that were found to be relevant for the present systematic review. An association between TMD and posterior crossbite (Yes-group) was reported as often as absence of such a relationship (No-group). The samples in the two groups showed similarities as well as differences with respect to number, gender, and age. Most articles reported only on 'presence' or 'absence' of crossbite and only few on type of crossbite opposite to a thorough account of clinical signs and symptoms of TMD. This review seems, however, to state that a functional posterior crossbite (mandibular guidance with midline deviation) is associated with headache, temporomandibular joint and muscular pain, and clicking. As evident from the discussion, such type needs orthodontic treatment to rehabilitate the asymmetric muscular activity between the crossbite and non-crossbite sides and the changed condyle/temporal relationship caused by mandibular deviation. Whether this treatment also will avoid future TMD problems can be answered only after clinical follow-up studies have been performed. PMID:21896884

  5. Diode laser photocoagulation for prethreshold, posterior retinopathy of prematurity.

    PubMed

    Fleming, T N; Runge, P E; Charles, S T

    1992-11-15

    Nine infants with posterior retinopathy of prematurity were treated by using the diode laser through an indirect ophthalmoscopic delivery system. Treatment was commenced as soon as plus disease (defined as tortuosity and dilation of posterior vessels) developed. We defined posterior retinopathy of prematurity as retinopathy of prematurity located in zone 1 (the limits of zone 1 are defined as twice the disk-fovea distance in all directions from the optic disk, that is, an arc of 60 degrees centered on the optic disk) or the posterior one half of zone 2 (zone 2 extends from the edge of zone 1 peripherally to a point tangential to the nasal ora serrata and around to an area near the temporal anatomic equator). Disease regressed in all eyes. These results are encouraging and represent an improvement over the results obtained by allowing these eyes to reach threshold (threshold disease is defined as 5 or more contiguous or 8 total clock hours of neovascularization in zone 1 or 2 in the presence of plus disease) before intervention. PMID:1443021

  6. Ear lobe reconstruction with a posterior ear flap. Case reports.

    PubMed

    Savaci, N; Tosun, Z; Hoşnuter, M

    2000-06-01

    We describe a technique for reconstruction of the ear lobe. Although there are many procedures that aim to reconstruct the ear lobe naturally, the aesthetic results of using a posterior ear flap are better because the scar tissue that remains behind the ear is invisible. PMID:10900635

  7. Posterior choroidal leiomyoma: a rare case report and literature review.

    PubMed

    Chiang, Wei-Yu; Lin, Jui-Wei; Yang, I-Hui; Kuo, Hsi-Kung

    2015-06-01

    We report a literature review and detailed evaluation of a rare case of posterior choroidal leiomyoma to emphasize the importance of differentiating this from other choroidal tumors. A 30-year-old male presented with variable blurred vision in his right eye secondary to a choroidal tumor. Clinical examinations were performed including fundus photography, optical coherence tomography, B scans, fluorescein and indocyanine green angiography, computed tomography, and magnetic resonance imaging. Preoperative examination revealed a suspected choroidal melanoma and enucleation was performed. However, a definitive diagnosis of choroidal leiomyoma was made following postoperative pathological light microscopy and immunohistochemical studies. Published case reports were collected and the common characteristics and distinctive features were compared with the current case. Posterior choroidal leiomyoma was summarized from the literature, and beneficial information for diagnosis and treatment was obtained. In conclusion, posterior choroidal leiomyoma is rare and should be differentiated from amelanotic melanomas. Despite the benign nature, an explanation regarding the rare incidence and difficult diagnosis of posterior choroidal leiomyoma must be provided to patients, prior to enucleation or detrimental treatment. PMID:25907891

  8. Atrial natriuretic factor-like activity in rat posterior pituitary

    SciTech Connect

    Gutkowska, J.; Debinski, W.; Racz, K.; Thibault, G.; Garcia, R.; Kuchel, O.; Genest, J.; Cantin, M.

    1986-03-05

    The presence of a biologically active peptide: Atrial Natriuretic Factor (ANF) has been demonstrated in rat and human circulation and ANF is considered now as a new hormone. ANF may be involved in body fluid regulation. A very sensitive radioimmunoassay for rat ANF allowed the authors to search for immunoreactive ANF (IR-ANF) in rat posterior pituitary. Serial dilutions of homogenates of rat posterior pituitary showed a good parallelism with a reference curve in a radioimmunoassay system. The IR-ANF was extracted from rat posterior pituitary homogenates by activated Vycor glass beads. The lyophilized extract was purified by HPLC on C/sub 18/ ..mu.. Bondapak column. The HPLC yielded two IR-ANF peaks. Both isolated ANF-like material showed biological activity. The IR-ANF eluted with 33% acetonitrile, inhibited ACTH-stimulated aldosterone secretion with a similar potency as synthetic (Arg 101 - Tyr 126) ANF (0.7 x 10/sup -10/M). A much less potent ANF-like material was found in the second peak eluted with 36% acetonitrile. They conclude that ANF-like material is present in rat posterior pituitary and this suggest a possible role in ANF on AVP secretion directly in situ.

  9. The Cognitive Substrate of Subjective Probability

    ERIC Educational Resources Information Center

    Nilsson, Hakan; Olsson, Henrik; Juslin, Peter

    2005-01-01

    The prominent cognitive theories of probability judgment were primarily developed to explain cognitive biases rather than to account for the cognitive processes in probability judgment. In this article the authors compare 3 major theories of the processes and representations in probability judgment: the representativeness heuristic, implemented as…

  10. 47 CFR 1.1623 - Probability calculation.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 1 2014-10-01 2014-10-01 false Probability calculation. 1.1623 Section 1.1623... Selection Procedures for Mass Media Services General Procedures § 1.1623 Probability calculation. (a) All calculations shall be computed to no less than three significant digits. Probabilities will be truncated to...

  11. Using Playing Cards to Differentiate Probability Interpretations

    ERIC Educational Resources Information Center

    López Puga, Jorge

    2014-01-01

    The aprioristic (classical, naïve and symmetric) and frequentist interpretations of probability are commonly known. Bayesian or subjective interpretation of probability is receiving increasing attention. This paper describes an activity to help students differentiate between the three types of probability interpretations.

  12. Pre-Service Teachers' Conceptions of Probability

    ERIC Educational Resources Information Center

    Odafe, Victor U.

    2011-01-01

    Probability knowledge and skills are needed in science and in making daily decisions that are sometimes made under uncertain conditions. Hence, there is the need to ensure that the pre-service teachers of our children are well prepared to teach probability. Pre-service teachers' conceptions of probability are identified, and ways of helping them…

  13. Illustrating Basic Probability Calculations Using "Craps"

    ERIC Educational Resources Information Center

    Johnson, Roger W.

    2006-01-01

    Instructors may use the gambling game of craps to illustrate the use of a number of fundamental probability identities. For the "pass-line" bet we focus on the chance of winning and the expected game length. To compute these, probabilities of unions of disjoint events, probabilities of intersections of independent events, conditional probabilities…

  14. Lévy processes in free probability

    PubMed Central

    Barndorff-Nielsen, Ole E.; Thorbjørnsen, Steen

    2002-01-01

    This is the continuation of a previous article that studied the relationship between the classes of infinitely divisible probability measures in classical and free probability, respectively, via the Bercovici–Pata bijection. Drawing on the results of the preceding article, the present paper outlines recent developments in the theory of Lévy processes in free probability. PMID:12473745

  15. Teaching Probabilities and Statistics to Preschool Children

    ERIC Educational Resources Information Center

    Pange, Jenny

    2003-01-01

    This study considers the teaching of probabilities and statistics to a group of preschool children using traditional classroom activities and Internet games. It was clear from this study that children can show a high level of understanding of probabilities and statistics, and demonstrate high performance in probability games. The use of Internet…

  16. Anterior and posterior corneal stroma elasticity assessed using nanoindentation

    PubMed Central

    Dias, Janice; Ziebarth, Nol M.

    2013-01-01

    Corneal biomechanics is an essential parameter for developing diagnostic and treatment methods of corneal-related diseases. It is widely accepted that corneal mechanical strength stems from the stroma's collagenous composition. However, more comprehensive insight into the mechanical properties within the stroma is needed to improve current corneal diagnostic and treatment techniques. The purpose of this study was to perform elasticity characterization of anterior and posterior stromal regions of human corneas using atomic force microscopy (AFM). Nine pairs of human whole globes were placed in 20% Dextran solution, cornea side down, to restore the corneal thickness to physiological levels (400-600?m). The epithelium and Bowman's membrane were removed from all eyes. Anterior stromal AFM elasticity testing was then performed on left (OS) eyes. Additional stroma was removed from right (OD) eyes to allow posterior stromal measurements at a depth of 50% of the original thickness. All experiments were performed with corneas submerged in 15% Dextran to maintain corneal hydration. The results of the study showed that the Young's modulus of elasticity of the anterior stroma (average: 281 214kPa; range: 59-764kPa) was significantly higher than that of the posterior stroma (average: 89.5 46.1kPa; range: 29-179kPa) (p=0.014). In addition, a linear relationship was found between the posterior stromal elasticity and anterior stromal elasticity (p=0.0428). On average, the elasticity of the posterior stroma is 39.3% of the anterior stroma. In summary, there appears to be an elasticity gradient within the corneal stroma, which should be considered in the design and development of corneal diagnostic and treatment methods to enhance efficacy. PMID:23800511

  17. Inhibition of Wnt activity induces heart formation from posterior mesoderm

    PubMed Central

    Marvin, Martha J.; Di Rocco, Giuliana; Gardiner, Aaron; Bush, Sara M.; Lassar, Andrew B.

    2001-01-01

    In the chick, heart mesoderm is induced by signals from the anterior endoderm. Although BMP-2 is expressed in the anterior endoderm, BMP activity is necessary but not sufficient for heart formation. Previous work from our lab has suggested that one or more additional factors from anterior endoderm are required. Crescent is a Frizzled-related protein that inhibits Wnt-8c and is expressed in anterior endoderm during gastrulation. At the same stages, expression of Wnt-3a and Wnt-8c is restricted to the primitive streak and posterior lateral plate, and is absent from the anterior region where crescent is expressed. Posterior lateral plate mesoderm normally forms blood, but coculture of this tissue with anterior endoderm or infection with RCAS–crescent induces formation of beating heart muscle and represses formation of blood. Dkk-1, a Wnt inhibitor of a different protein family, similarly induces heart-specific gene expression in posterior lateral plate mesoderm. Furthermore, we have found that ectopic Wnt signals can repress heart formation from anterior mesoderm in vitro and in vivo and that forced expression of either Wnt-3a or Wnt-8c can promote development of primitive erythrocytes from the precardiac region. We conclude that inhibition of Wnt signaling promotes heart formation in the anterior lateral mesoderm, whereas active Wnt signaling in the posterior lateral mesoderm promotes blood development. We propose a model in which two orthogonal gradients, one of Wnt activity along the anterior-posterior axis and the other of BMP signals along the dorsal-ventral axis, intersect in the heart-forming region to induce cardiogenesis in a region of high BMP and low Wnt activity. PMID:11159912

  18. Robotic Posterior Mitral Leaflet Repair: Neochordal versus Resectional Techniques

    PubMed Central

    Mihaljevic, Tomislav; Pattakos, Gregory; Gillinov, A. Marc; Bajwa, Gurjyot; Planinc, Mislav; Williams, Sarah J.; Blackstone, Eugene H.

    2013-01-01

    Background Resectional techniques are the established method of posterior mitral valve leaflet repair for degenerative disease; however, use of neochordae in a robotically assisted approach is gaining acceptance because of its versatility for difficult multi-segment disease. The purposes of this study were to compare the versatility, safety, and effectiveness of neochordal vs. resectional techniques for robotic posterior mitral leaflet repair. Methods From 12/2007 to 7/2010, 334 patients underwent robotic posterior mitral leaflet repair for degenerative disease by a resectional (n=248) or neochordal (n=86) technique. Outcomes were compared unadjusted and after propensity score matching. Results Neochordae were more likely to be used than resection in patients with two (28% vs. 13%, P=.002) or three (3.7% vs. 0.87%, P=.08) diseased posterior leaflet segments. Three resection patients (0.98%) but no neochordal patient required reoperation for hemodynamically significant systolic anterior motion (SAM). Residual mitral regurgitation (MR) at hospital discharge was similar for matched neochordal vs. resection patients (P=.14) (MR 0+, 82% vs. 89%; MR 1+, 14% vs. 8.2%; MR 2+, 2.3% vs. 2.6%; one neochordal patient had 4+ MR and was reoperated). Among matched patients, postoperative mortality and morbidity were similarly low. Conclusion Compared with a resectional technique, robotic posterior mitral leaflet repair with neochordae is associated with shorter operative times and no occurrence of SAM. The versatility, effectiveness, and safety of this repair make it a good choice for patients with advanced multi-segment disease. PMID:23103008

  19. Anterior and posterior corneal stroma elasticity assessed using nanoindentation.

    PubMed

    Dias, Janice M; Ziebarth, Noël M

    2013-10-01

    Corneal biomechanics is an essential parameter for developing diagnostic and treatment methods of corneal-related diseases. It is widely accepted that corneal mechanical strength stems from the stroma's collagenous composition. However, more comprehensive insight into the mechanical properties within the stroma is needed to improve current corneal diagnostic and treatment techniques. The purpose of this study was to perform elasticity characterization of anterior and posterior stromal regions of human corneas using atomic force microscopy (AFM). Nine pairs of human whole globes were placed in 20% Dextran solution, cornea side down, to restore the corneal thickness to physiological levels (400-600 μm). The epithelium and Bowman's membrane were removed from all eyes. Anterior stromal AFM elasticity testing was then performed on left (OS) eyes. Additional stroma was removed from right (OD) eyes to allow posterior stromal measurements at a depth of 50% of the original thickness. All experiments were performed with corneas submerged in 15% Dextran to maintain corneal hydration. The results of the study showed that the Young's modulus of elasticity of the anterior stroma (average: 281 ± 214 kPa; range: 59-764 kPa) was significantly higher than that of the posterior stroma (average: 89.5 ± 46.1 kPa; range: 29-179 kPa) (p = 0.014). In addition, a linear relationship was found between the posterior stromal elasticity and anterior stromal elasticity (p = 0.0428). On average, the elasticity of the posterior stroma is 39.3% of the anterior stroma. In summary, there appears to be an elasticity gradient within the corneal stroma, which should be considered in the design and development of corneal diagnostic and treatment methods to enhance efficacy. PMID:23800511

  20. Anomalous vertebral and posterior communicating arteries as a risk factor in instrumentation of the posterior cervical spine.

    PubMed

    Nagahama, K; Sudo, H; Abumi, K; Ito, M; Takahata, M; Hiratsuka, S; Kuroki, K; Iwasaki, N

    2014-04-01

    We investigated the incidence of anomalies in the vertebral arteries and Circle of Willis with three-dimensional CT angiography in 55 consecutive patients who had undergone an instrumented posterior fusion of the cervical spine. We recorded any peri-operative and post-operative complications. The frequency of congenital anomalies was 30.9%, abnormal vertebral artery blood flow was 58.2% and vertebral artery dominance 40%. The posterior communicating artery was occluded on one side in 41.8% of patients and bilaterally in 38.2%. Variations in the vertebral arteries and Circle of Willis were not significantly related to the presence or absence of posterior communicating arteries. Importantly, 18.2% of patients showed characteristic variations in the Circle of Willis with unilateral vertebral artery stenosis or a dominant vertebral artery, indicating that injury may cause lethal complications. One patient had post-operative cerebellar symptoms due to intra-operative injury of the vertebral artery, and one underwent a different surgical procedure because of insufficient collateral circulation. Pre-operative assessment of the vertebral arteries and Circle of Willis is essential if a posterior spinal fusion with instrumentation is to be carried out safely. PMID:24692624

  1. The stability of the cemented tibial component of total knee arthroplasty: posterior cruciate-retaining versus posterior-stabilized design.

    PubMed

    Catani, Fabio; Leardini, Alberto; Ensini, Andrea; Cucca, Giuseppe; Bragonzoni, Laura; Toksvig-Larsen, Soren; Giannini, Sandro

    2004-09-01

    Micromotion of the tibial component in 40 knee arthroplasties for gonarthrosis was studied using Roentgen stereophotogrammetric analysis. The stability of this component was assessed for 2 years' postoperatively. In all arthroplasties, an attempt was made to reconstruct the preoperative posterior slope. Posterior cruciate-retaining (CR) and posterior-stabilized (PS) components showed at 2 years a maximum total point motion of 0.6 +/- 0.4 mm and 0.7 +/- 0.5 mm, respectively. Whereas 92.5% of the implants were determined to be stable, 1 of the CR group and 2 of the PS group displayed migration between the first and the second year of at least 0.2 mm. A negative correlation between subsidence of the tibial component at 2 years of follow-up and the difference between preoperative and postoperative tibial slope was found. Consequently, we suggest that restoring the original posterior slope of the tibial plateau must be a goal of tibial component implantation. PMID:15343540

  2. Calibrating Subjective Probabilities Using Hierarchical Bayesian Models

    NASA Astrophysics Data System (ADS)

    Merkle, Edgar C.

    A body of psychological research has examined the correspondence between a judge's subjective probability of an event's outcome and the event's actual outcome. The research generally shows that subjective probabilities are noisy and do not match the "true" probabilities. However, subjective probabilities are still useful for forecasting purposes if they bear some relationship to true probabilities. The purpose of the current research is to exploit relationships between subjective probabilities and outcomes to create improved, model-based probabilities for forecasting. Once the model has been trained in situations where the outcome is known, it can then be used in forecasting situations where the outcome is unknown. These concepts are demonstrated using experimental psychology data, and potential applications are discussed.

  3. Integrated statistical modelling of spatial landslide probability

    NASA Astrophysics Data System (ADS)

    Mergili, M.; Chu, H.-J.

    2015-09-01

    Statistical methods are commonly employed to estimate spatial probabilities of landslide release at the catchment or regional scale. Travel distances and impact areas are often computed by means of conceptual mass point models. The present work introduces a fully automated procedure extending and combining both concepts to compute an integrated spatial landslide probability: (i) the landslide inventory is subset into release and deposition zones. (ii) We employ a simple statistical approach to estimate the pixel-based landslide release probability. (iii) We use the cumulative probability density function of the angle of reach of the observed landslide pixels to assign an impact probability to each pixel. (iv) We introduce the zonal probability i.e. the spatial probability that at least one landslide pixel occurs within a zone of defined size. We quantify this relationship by a set of empirical curves. (v) The integrated spatial landslide probability is defined as the maximum of the release probability and the product of the impact probability and the zonal release probability relevant for each pixel. We demonstrate the approach with a 637 km2 study area in southern Taiwan, using an inventory of 1399 landslides triggered by the typhoon Morakot in 2009. We observe that (i) the average integrated spatial landslide probability over the entire study area corresponds reasonably well to the fraction of the observed landside area; (ii) the model performs moderately well in predicting the observed spatial landslide distribution; (iii) the size of the release zone (or any other zone of spatial aggregation) influences the integrated spatial landslide probability to a much higher degree than the pixel-based release probability; (iv) removing the largest landslides from the analysis leads to an enhanced model performance.

  4. 38 CFR 4.46 - Accurate measurement.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 38 Pensions, Bonuses, and Veterans' Relief 1 2011-07-01 2011-07-01 false Accurate measurement. 4.46 Section 4.46 Pensions, Bonuses, and Veterans' Relief DEPARTMENT OF VETERANS AFFAIRS SCHEDULE FOR RATING DISABILITIES Disability Ratings The Musculoskeletal System § 4.46 Accurate measurement....

  5. Exact probability-density function for phase-measurement interferometry

    NASA Astrophysics Data System (ADS)

    Ho, Keang-Po; Kahn, Joseph M.

    1995-09-01

    Conventional analyses of the accuracy of phase-measurement interferometry derive a figure of merit that is either a variance or a signal-to-noise ratio. We derive the probability-density function of the phase-measurement output, so that the measurement confidence interval can be determined. We include both laser phase noise and additive Gaussian noise, and we consider both unmodulated interferometers and those employing phase or frequency modulation. For both unmodulated and modulated interferometers the confidence interval can be obtained by numerical integration of the probability-density function. For the modulated interferometer we derive a series summation for the confidence interval. For both unmodulated and modulated interferometers we derive approximate analytical expressions for the confidence interval, which we show to be extremely accurate at high signal-to-noise ratios.

  6. Optimized Algorithm for Collision Probability Calculations in Cubic Geometry

    SciTech Connect

    Garcia, R.D.M.

    2004-06-15

    An optimized algorithm for implementing a recently developed method of computing collision probabilities (CPs) in three dimensions is reported in this work for the case of a homogeneous cube. Use is made of the geometrical regularity of the domain to rewrite, in a very compact way, the approximate formulas for calculating CPs in general three-dimensional geometry that were derived in a previous work by the author. The ensuing gain in computation time is found to be substantial: While the computation time associated with the general formulas increases as K{sup 2}, where K is the number of elements used in the calculation, that of the specific formulas increases only linearly with K. Accurate numerical results are given for several test cases, and an extension of the algorithm for computing the self-collision probability for a hexahedron is reported at the end of the work.

  7. CORBITS: Efficient Geometric Probabilities of Multi-Transiting Exoplanetary Systems

    NASA Astrophysics Data System (ADS)

    Brakensiek, Joshua; Ragozzine, Darin

    2016-03-01

    CORBITS (Computed Occurrence of Revolving Bodies for the Investigation of Transiting Systems) computes the probability that any particular group of exoplanets can be observed to transit from a collection of conjectured exoplanets orbiting a star. The efficient, semi-analytical code computes the areas bounded by circular curves on the surface of a sphere by applying elementary differential geometry. CORBITS is faster than previous algorithms, based on comparisons with Monte Carlo simulations, and tests show that it is extremely accurate even for highly eccentric planets.

  8. Supervised learning of probability distributions by neural networks

    NASA Technical Reports Server (NTRS)

    Baum, Eric B.; Wilczek, Frank

    1988-01-01

    Supervised learning algorithms for feedforward neural networks are investigated analytically. The back-propagation algorithm described by Werbos (1974), Parker (1985), and Rumelhart et al. (1986) is generalized by redefining the values of the input and output neurons as probabilities. The synaptic weights are then varied to follow gradients in the logarithm of likelihood rather than in the error. This modification is shown to provide a more rigorous theoretical basis for the algorithm and to permit more accurate predictions. A typical application involving a medical-diagnosis expert system is discussed.

  9. DREAM(D): an adaptive markov chain monte carlo simulation algorithm to solve discrete, noncontinuous, posterior parameter estimation problems

    NASA Astrophysics Data System (ADS)

    Vrugt, J. A.

    2011-04-01

    Formal and informal Bayesian approaches are increasingly being used to treat forcing, model structural, parameter and calibration data uncertainty, and summarize hydrologic prediction uncertainty. This requires posterior sampling methods that approximate the (evolving) posterior distribution. We recently introduced the DiffeRential Evolution Adaptive Metropolis (DREAM) algorithm, an adaptive Markov Chain Monte Carlo (MCMC) method that is especially designed to solve complex, high-dimensional and multimodal posterior probability density functions. The method runs multiple chains in parallel, and maintains detailed balance and ergodicity. Here, I present the latest algorithmic developments, and introduce a discrete sampling variant of DREAM that samples the parameter space at fixed points. The development of this new code, DREAM(D), has been inspired by the existing class of integer optimization problems, and emerging class of experimental design problems. Such non-continuous parameter estimation problems are of considerable theoretical and practical interest. The theory developed herein is applicable to DREAM(ZS) (Vrugt et al., 2011) and MT-DREAM(ZS) (Laloy and Vrugt, 2011) as well. Two case studies involving a sudoku puzzle and rainfall - runoff model calibration problem are used to illustrate DREAM(D).

  10. Target intersection probabilities for parallel-line and continuous-grid types of search

    USGS Publications Warehouse

    McCammon, R.B.

    1977-01-01

    The expressions for calculating the probability of intersection of hidden targets of different sizes and shapes for parallel-line and continuous-grid types of search can be formulated by vsing the concept of conditional probability. When the prior probability of the orientation of a widden target is represented by a uniform distribution, the calculated posterior probabilities are identical with the results obtained by the classic methods of probability. For hidden targets of different sizes and shapes, the following generalizations about the probability of intersection can be made: (1) to a first approximation, the probability of intersection of a hidden target is proportional to the ratio of the greatest dimension of the target (viewed in plane projection) to the minimum line spacing of the search pattern; (2) the shape of the hidden target does not greatly affect the probability of the intersection when the largest dimension of the target is small relative to the minimum spacing of the search pattern, (3) the probability of intersecting a target twice for a particular type of search can be used as a lower bound if there is an element of uncertainty of detection for a particular type of tool; (4) the geometry of the search pattern becomes more critical when the largest dimension of the target equals or exceeds the minimum spacing of the search pattern; (5) for elongate targets, the probability of intersection is greater for parallel-line search than for an equivalent continuous square-grid search when the largest dimension of the target is less than the minimum spacing of the search pattern, whereas the opposite is true when the largest dimension exceeds the minimum spacing; (6) the probability of intersection for nonorthogonal continuous-grid search patterns is not greatly different from the probability of intersection for the equivalent orthogonal continuous-grid pattern when the orientation of the target is unknown. The probability of intersection for an elliptically shaped target can be approximated by treating the ellipse as intermediate between a circle and a line. A search conducted along a continuous rectangular grid can be represented as intermediate between a search along parallel lines and along a continuous square grid. On this basis, an upper and lower bound for the probability of intersection of an elliptically shaped target for a continuous rectangular grid can be calculated. Charts have been constructed that permit the values for these probabilities to be obtained graphically. The use of conditional probability allows the explorationist greater flexibility in considering alternate search strategies for locating hidden targets. ?? 1977 Plenum Publishing Corp.

  11. Asymptomatic solitary cerebral metastasis from papillary carcinoma thyroid: 131I SPECT/CT for accurate staging.

    PubMed

    Jain, Tarun Kumar; Karunanithi, Sellam; Sharma, Punit; Vijay, Maneesh Kumar; Ballal, Sanjana; Bal, Chandrasekhar

    2014-11-01

    Isolated asymptomatic brain metastasis in papillary carcinoma thyroid (PCT) is extremely rare. We here present such a case of a 48-year-old woman with PCT. SPECT/CT localized the 131I radiotracer concentration seen on whole-body scan in this patient to the right posterior parietal cortex, suggesting brain metastasis. Contrast-enhanced MRI and 18F-FDG PET/CT confirmed the diagnosis and the patient was taken for gamma-knife radiosurgery. 131I SPECT/CT in this case accurately restaged the patient by detecting asymptomatic isolated brain metastasis and correctly directed the management strategy. PMID:24566406

  12. Population variability complicates the accurate detection of climate change responses.

    PubMed

    McCain, Christy; Szewczyk, Tim; Bracy Knight, Kevin

    2016-06-01

    The rush to assess species' responses to anthropogenic climate change (CC) has underestimated the importance of interannual population variability (PV). Researchers assume sampling rigor alone will lead to an accurate detection of response regardless of the underlying population fluctuations of the species under consideration. Using population simulations across a realistic, empirically based gradient in PV, we show that moderate to high PV can lead to opposite and biased conclusions about CC responses. Between pre- and post-CC sampling bouts of modeled populations as in resurvey studies, there is: (i) A 50% probability of erroneously detecting the opposite trend in population abundance change and nearly zero probability of detecting no change. (ii) Across multiple years of sampling, it is nearly impossible to accurately detect any directional shift in population sizes with even moderate PV. (iii) There is up to 50% probability of detecting a population extirpation when the species is present, but in very low natural abundances. (iv) Under scenarios of moderate to high PV across a species' range or at the range edges, there is a bias toward erroneous detection of range shifts or contractions. Essentially, the frequency and magnitude of population peaks and troughs greatly impact the accuracy of our CC response measurements. Species with moderate to high PV (many small vertebrates, invertebrates, and annual plants) may be inaccurate 'canaries in the coal mine' for CC without pertinent demographic analyses and additional repeat sampling. Variation in PV may explain some idiosyncrasies in CC responses detected so far and urgently needs more careful consideration in design and analysis of CC responses. PMID:26725404

  13. Vascularized posterior interosseous pedicled bone grafting for infected forearm nonunion.

    PubMed

    Kamrani, R S; Farhoud, A; Nabian, M H; Zanjani, L O; Farzan, M

    2016-05-01

    Infected forearm nonunion is challenging to treat. We have used a vascularized pedicled bone graft from the distal ulna based on the posterior interosseous artery to treat forearm nonunion with current or previous signs of infection in six patients. Bone union was achieved after a mean of 3.8 months. After a mean follow-up of 25.7 months, no signs of persistent or reactivation of infection were seen in any patient. The mean Quick DASH score significantly improved from 77.4 to 17.6. In addition, the active range of motion of the wrist improved significantly after surgery. In our patients, a vascularized posterior interosseous pedicled bone from the distal ulna is a reliable vascularized bone graft for managing infected forearm nonunion.The Level of evidence of this study is 4. PMID:26307139

  14. Postural stability and unilateral posterior crossbite: is there a relationship?

    PubMed

    Michelotti, Ambrosina; Buonocore, Gerarda; Farella, Mauro; Pellegrino, Gioacchino; Piergentili, Carlo; Altobelli, Stefano; Martina, Roberto

    2006-01-01

    The aim of this study was to test the hypothesis that unilateral posterior crossbite influences postural stability of the whole body. Twenty-six subjects (14 males and 12 females) affected with unilateral posterior crossbite were selected and compared with 52 controls matched for age and gender. Postural stability was assessed using a stabilometric platform. The following stabilometric measurements were assessed: weight distribution on foot area and speed of body sway. Tests were performed under two occlusal conditions: teeth in intercuspal position (ICP) and while keeping two cotton rolls between teeth without clenching. The weight distribution on foot area and the speed of body sway were not significantly influenced from crossbite (with and without lateral mandibular slide), occlusal conditions (ICP, cotton rolls), and gender. Therefore, the treatment of this malocclusion in order to prevent or to treat postural disorders is not justified. PMID:16225992

  15. Pregnancy Enhances the Effects of Hypercholesterolemia on Posterior Cerebral Arteries

    PubMed Central

    Schreurs, Malou P. H.

    2013-01-01

    In preeclampsia, hyperlipidemia is enhanced compared to normal pregnancy that could adversely affect vascular function. In the cerebral vasculature, this could lead to dysregulation of cerebral blood flow and neurological complications. Here, we examined the effect of excessive hyperlipidemia, as seen in preeclampsia, on cerebral artery function and expression of inflammatory markers in pregnancy. Pregnant and nonpregnant rats received a 14-day high-cholesterol diet or normal chow and posterior cerebral artery function was compared. High cholesterol significantly increased sensitivity of posterior cerebral arteries to the nitric oxide donor sodium nitroprusside that was accompanied by a ~12-fold increased messenger RNA (mRNA) expression of inducible nitric oxide synthase in late-pregnant rats only. Further, high cholesterol significantly increased peroxynitrite-induced dilation and decreased myogenic tone in cerebral arteries from late pregnant compared to nonpregnant animals. These results suggest that pathologically high levels of cholesterol in pregnancy enhance inflammatory responses and peroxynitrite generation in cerebral arteries. PMID:23171682

  16. Posterior reversible encephalopathy syndrome with neurological sequelae - a case report.

    PubMed

    Nesteruk, Marta; Kurdyła, Anna; Nesteruk, Tomasz; Dorobek, Małgorzata

    2016-04-29

    Posterior reversible encephalopathy syndrome (PRES) is a set of neurological symptoms including impaired consciousness, cognitive disorders, seizures, blurred vision, dizziness and headache. The symptoms are closely related to the location of pathological changes in the brain; bilateral occipitto-parietal region is most often affected. Both focal neurological symptoms and encephalopathy are usually transient. We present the case of 64-year-old woman with PRES. She suffered from many internal diseases and was admitted to the hospital due to impaired consciousness, speech disorders, balance disorders. Significant neurological deterioration was observed within several days from the onset. Differential diagnosis included stroke and viral neuroinfection (cytosis 23 cells /ul, protein level of 93 mg/dl); magnetic resonance examination revealed lesions typical for posterior reversible encephalopathy.After 6 weeks of hospitalization patient condition improved, but did not restore to the premorbid state. The patient was discharged with generalized cognitive impairment. PMID:27137827

  17. A case of giant nodular posterior scleritis mimicking choroidal malignancy

    PubMed Central

    Liu, Andrea T; Luk, Fiona O; Chan, Carmen K

    2015-01-01

    To report a case of giant nodular posterior scleritis mimicking a choroidal tumor. A 42-year-old lady with systemic hypertension presented with a 1-week history of unilateral visual loss, pain and redness in her left eye. Examination showed sectoral anterior episcleritis in her left eye as well as a dome-shaped choroidal mass at the inferior-temporal periphery, associated with retinal hemorrhages and subretinal fluid. Systemic evaluation and imaging of the choroidal mass were performed and could not rule out amelanotic choroidal melanoma. At the same time, she was prescribed a 2-week course of oral nonsteroidal anti-inflammatory drug (NSAID) for her sectoral anterior episcleritis. The choroidal mass was found to have resolved completely right before her scheduled fine needle biospy. Diagnosis of nodular posterior scleritis and a trial of oral NSAID can be considered in patients presenting with a choroidal mass before any invasive procedure. PMID:26862098

  18. Oblique posterior trochanteric osteotomy in revision total hip arthroplasty.

    PubMed

    Stuchin, Steven A; Millman, Jennifer S

    2011-04-01

    Modular polyethylene failure and attendant revision play an increasing role in hip arthroplasty. In spite of well-fixed, well-aligned components, bearing exchange has a high risk of chronic instability, which may be attributed to the resection of stabilizing soft tissue structures to gain exposure. This creates a difficult situation for the surgeon and an inexplicable one for the patient with a previously well-functioning implant. The senior author modified a technique previously described by Shaw that included an osteotomy of the posterior one third of the greater trochanter and preservation of posterior soft tissues. Thirty-five patients underwent 47 revision procedures utilizing this approach, including 16 modular component and 31 more extensive procedures. There were no dislocations or significant complications and no loss of reduction or nonunion. The approach offers excellent exposure while preserving stabilizing soft tissues. PMID:20541890

  19. Posterior Reversible Encephalopathy Syndrome in late postpartum eclampsia.

    PubMed

    Pezzi, M; Le Piane, E; Giglio, A M; Pagnotta, L; Scozzafava, A; Tortorella, V; Sergi, A; Verre, M

    2015-01-01

    Posterior Reversible Encephalopathy Syndrome (PRES) is a neurological complication associated with several medical conditions and it has been described in clinical findings of seizures, headache, vomiting, altered mental status, and visual changes and focal neurologic deficit, in conjunction with radiological findings of primarily posterior cerebral white matter edema of both cerebral hemispheres. PRES can develop in a wide array situations including pregnancy and postpartum in patients with or without symptoms and signs of eclampsia. A prompt diagnosis of PRES by magnetic resonance imaging and an immediate antihypertensive and anticonvulsant therapy can help to prevent serious complications. The clinical case presented deals with a 35 year-old pregnant woman whose history of eclampsia was observed after a cesarean section. PMID:25945433

  20. Clinical Characteristics of Posterior and Lateral Semicircular Canal Dehiscence.

    PubMed

    Spasic, Marko; Trang, Andy; Chung, Lawrance K; Ung, Nolan; Thill, Kimberly; Zarinkhou, Golmah; Gopen, Quinton S; Yang, Isaac

    2015-12-01

    The objective of this study was to evaluate the characteristic symptoms of and treatments for lateral semicircular canal dehiscence (LSCD) and posterior semicircular canal dehiscence (PSCD) and its proposed mechanism. A dehiscence acquired in any of the semicircular canals may evoke various auditory symptoms (autophony and inner ear conductive hearing loss) or vestibular symptoms (vertigo, the Tullio phenomenon, and Hennebert sign) by creating a "third mobile window" in the bone that enables aberrant communication between the inner ear and nearby structures. A PubMed search was performed using the keywords lateral, posterior, and semicircular canal dehiscence to identify all relevant cases. Our data suggest that PSCD, although clinically rare, is most likely associated with a high-riding jugular bulb and fibrous dysplasia. Patients may experience auditory manifestations that range from mild conductive to extensive sensorineural hearing loss. LSCD is usually associated with chronic otitis media with cholesteatoma. PMID:26682120

  1. Which Approach for Total Hip Arthroplasty: Anterolateral or Posterior?

    PubMed Central

    Palan, Jeya; Murray, David W.; Andrew, J. G.; Nolan, John

    2008-01-01

    The best approach to use when performing THA is controversial. We did a prospective, nonrandomized multicenter study of 1089 THAs to evaluate patient-centered hip scores and dislocation and revision rates when comparing anterolateral and posterior hip approaches at 5 years’ followup. Patients were divided into two groups depending on which surgical approach was used: anterolateral or posterior. The primary outcome measure was change in Oxford hip score. At 5 years, there were no differences in change in Oxford hip score and in dislocation or revision rates between the groups. Level of Evidence: Level II, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence. PMID:18941858

  2. SHOULDER POSTERIOR INTERNAL IMPINGEMENT IN THE OVERHEAD ATHLETE

    PubMed Central

    Grant‐Nierman, Meggan; Lucas, Brennen

    2013-01-01

    Posterior internal impingement (PII) of the glenohumeral joint is a common cause of shoulder complex pain in the overhead athlete. This impingement is very different from standard outlet impingement seen in shoulder patients. Internal impingement is characterized by posterior shoulder pain when the athlete places the humerus in extreme external rotation and abduction as in the cocking phase of pitching or throwing. Impingement in this position occurs between the supraspinatus and or infraspinatus and the glenoid rim. Understanding regarding this pathology continues to evolve. Definitive understanding of precipitating factors, causes, presentation and methods of treatment have yet to be determined. A high index of suspicion should be used when attempting to make this diagnosis. This current concepts review presents the current thinking regarding pathophysiology, evaluation, and treatment of this condition. Level of Evidence: 5 PMID:23593557

  3. [Cysts in the posterior triangle of the neck in adults].

    PubMed

    Brea-Álvarez, Beatriz; Roldán-Hidalgo, Amaya

    2015-01-01

    Cystic lesions of the posterior triangle are a pathologic entity whose diagnosis is made in the first two years of life. Its presentation in adulthood is an incidental finding and the differential diagnosis includes cystic lymphangioma, lymphatic metastasis of thyroid cancer and branchial cyst. Often with the finding of a cervical lump, FNA is made before diagnostic imaging is performed, however, this procedure is not always advisable. We reviewed the cases of patients who came last year to our department with a cystic mass in this location and correlating the imaging findings with pathologic specimen. We show characteristic findings of these lesions in order to make an early diagnosis and thus to get the approach and treatment appropriate of adult patients with a cystic lesion in the posterior cervical triangle. PMID:24846559

  4. Ogilvie's syndrome following posterior spinal instrumentation in thoraco lumbar trauma

    PubMed Central

    Krishnakumar, R.; Kuzhimattam, Mathew John; Kumar, Gaurav

    2015-01-01

    Objectives: To report unique cases of Ogilvie's syndrome (acute intestinal pseudo-obstruction) following posterior spinal instrumentation in thoraco lumbar trauma. Materials and Methods: A single centre retrospective study. We reviewed the surgical data of 420 patients who underwent thoracolumbar spinal surgery over a period of four years. Two patients who developed post operative Ogilvie's syndromes were identified. Results: The clinical presentation and blood investigations ruled out any infectious pathology. Computed tomography scans ruled out the mechanical obstruction. All patients improved with conservative management. Conclusion: Ogilvie's syndrome should be considered as a differential diagnosis in patients with postoperative significant abdominal distension who had undergone posterior instrumentation for spinal trauma. Early recognition and appropriate conservative treatment would be necessary to prevent complications such as bowel ischemia and perforation. PMID:26692695

  5. A case of hypospadias, anterior and posterior urethral valves.

    PubMed

    Carvell, James; Mulik, Roopa

    2013-01-01

    This report outlines the case of a 3-year-old boy whose initial presentation was that of asymptomatic hypertension (lowest recording 148/90), found at preoperative check prior to stage 2-correction surgery for distal hypospadias. Upon diagnosis of true hypertension, an ultrasound of the child's renal tract showed evidence of marked hydronephrosis and calyceal dilatation. On the background of deteriorating renal function (Urea 25.5 and Creatinine 188), a Micturating Cystourethrogram was performed, demonstrating posterior urethral dilatation. With difficulties controlling blood pressure, the child was transferred to Urology care, where resection of a posterior urethral valve (PUV) was undertaken. Despite this, renal function deteriorated further and re-cystoscopy identified an anterior urethral valve (AUV), which was also resected. Renal function, although improved, remains poor and blood pressure is controlled with two anti-hypertensives. To the publisher's knowledge, the association between hypospadias, PUVs and AUVs is as yet undocumented. PMID:24964414

  6. Biomechanic effect of posterior cruciate ligament rupture on lateral meniscus

    PubMed Central

    Lei, Pengfei; Sun, Rongxin; Hu, Yihe; Li, Kanghua; Liao, Zhan

    2015-01-01

    Objective: This study aims to investigate the biomechanical effect of posterior cruciate ligament (PCL) rupture on lateral meniscus. Method: The stresses of anterior horn, caudomedial part and posterior horn of lateral meniscus in cadaveric knees were recorded when the knee joints were loaded 200 to 1000 N at 0, 30, 60 and 90° of flexion. Twelve knees were tested before PCL transection (intact group), and 6 each were then tested after anterolateral bundle (ALB group) and postmedial bundle (PMB group) transection. The same knees were finally tested after complete PCL transection. Result: At 0°of knee flexion, the stresses of the anterior horn, caudomedial part and posterior horn were negative and compressive, and were not significantly different between intact and ALB groups, and between completely transected and PMB groups at 200 and 400 N. The stresses of the anterior horn and caudomedial part were greater in completely transected and PMB groups than in intact and ALB groups. The stresses of the posterior horn were smaller in PMB and completely transected groups than in intact and ALB groups. At 600-1000 N, the stresses were significantly different between the groups. The absolute stresses of the anterior horn and caudomedial part were in order of completely transected > PMB > ALB > intact group, while these of the posterior horn were reversed. At 30° of knee flexion, the stresses of the three parts were not significantly different between intact and PMB groups nor between completely transected and ALB groups at 200 and 400 N. The stresses in the anterior horn and caudomedial part were negative and different between completely transected and ALB groups, and positive and different between intact and PMB groups. The stresses in the posterior horn were positive and different between completely transected and ALB groups, and negative and different between intact and PMB groups. At loads of > 600 N, the stresses in the anterior horn and caudomedial part were negative in completely transected and ALB groups, and positive in intact and PMB groups. The stresses of the posterior horn were positive in completely transected and ALB groups and negative in intact and PMB groups, with significant difference between the groups. At 60° and 90° of flexion, the stresses of the anterior horn and caudomedial part were positive in completely transected and ALB groups and positive in intact and PMB groups, while the stresses of posterior horn were in the opposite directions and were significantly different between the groups at the same loads. Conclusion: Complete transection of PCL will result in stress changes in various parts of lateral meniscus. At 200 and 400 N, transection of ALB and PMB do not change the stress at 0° and 30° of flexion, respectively. At heavier loads (600-1000 N), the stresses at these angels are affected in ALB and PMB groups. At all loaded tested, transection of ALB and PMB results in changed stresses in all regions of lateral meniscus at 30-90° and 0-90° of flexion, respectively. PMID:26309636

  7. Dynamic probability estimator for machine learning.

    PubMed

    Starzyk, Janusz A; Wang, Feng

    2004-03-01

    An efficient algorithm for dynamic estimation of probabilities without division on unlimited number of input data is presented. The method estimates probabilities of the sampled data from the raw sample count, while keeping the total count value constant. Accuracy of the estimate depends on the counter size, rather than on the total number of data points. Estimator follows variations of the incoming data probability within a fixed window size, without explicit implementation of the windowing technique. Total design area is very small and all probabilities are estimated concurrently. Dynamic probability estimator was implemented using a programmable gate array from Xilinx. The performance of this implementation is evaluated in terms of the area efficiency and execution time. This method is suitable for the highly integrated design of artificial neural networks where a large number of dynamic probability estimators can work concurrently. PMID:15384523

  8. Derivation of quantum probability from measurement

    NASA Astrophysics Data System (ADS)

    Herbut, Fedor

    2016-05-01

    To begin with, it is pointed out that the form of the quantum probability formula originates in the very initial state of the object system as seen when the state is expanded with the eigenprojectors of the measured observable. Making use of the probability reproducibility condition, which is a key concept in unitary measurement theory, one obtains the relevant coherent distribution of the complete-measurement results in the final unitary-measurement state in agreement with the mentioned probability formula. Treating the transition from the final unitary, or premeasurement, state, where all possible results are present, to one complete-measurement result sketchily in the usual way, the well-known probability formula is derived. In conclusion it is pointed out that the entire argument is only formal unless one makes it physical assuming that the quantum probability law is valid in the extreme case of probability-one (certain) events (projectors).

  9. Experience Matters: Information Acquisition Optimizes Probability Gain

    PubMed Central

    Nelson, Jonathan D.; McKenzie, Craig R.M.; Cottrell, Garrison W.; Sejnowski, Terrence J.

    2010-01-01

    Deciding which piece of information to acquire or attend to is fundamental to perception, categorization, medical diagnosis, and scientific inference. Four statistical theories of the value of information—information gain, Kullback-Liebler distance, probability gain (error minimization), and impact—are equally consistent with extant data on human information acquisition. Three experiments, designed via computer optimization to be maximally informative, tested which of these theories best describes human information search. Experiment 1, which used natural sampling and experience-based learning to convey environmental probabilities, found that probability gain explained subjects’ information search better than the other statistical theories or the probability-of-certainty heuristic. Experiments 1 and 2 found that subjects behaved differently when the standard method of verbally presented summary statistics (rather than experience-based learning) was used to convey environmental probabilities. Experiment 3 found that subjects’ preference for probability gain is robust, suggesting that the other models contribute little to subjects’ search behavior. PMID:20525915

  10. Probability and Quantum Paradigms: the Interplay

    SciTech Connect

    Kracklauer, A. F.

    2007-12-03

    Since the introduction of Born's interpretation of quantum wave functions as yielding the probability density of presence, Quantum Theory and Probability have lived in a troubled symbiosis. Problems arise with this interpretation because quantum probabilities exhibit features alien to usual probabilities, namely non Boolean structure and non positive-definite phase space probability densities. This has inspired research into both elaborate formulations of Probability Theory and alternate interpretations for wave functions. Herein the latter tactic is taken and a suggested variant interpretation of wave functions based on photo detection physics proposed, and some empirical consequences are considered. Although incomplete in a few details, this variant is appealing in its reliance on well tested concepts and technology.

  11. Probability and Quantum Paradigms: the Interplay

    NASA Astrophysics Data System (ADS)

    Kracklauer, A. F.

    2007-12-01

    Since the introduction of Born's interpretation of quantum wave functions as yielding the probability density of presence, Quantum Theory and Probability have lived in a troubled symbiosis. Problems arise with this interpretation because quantum probabilities exhibit features alien to usual probabilities, namely non Boolean structure and non positive-definite phase space probability densities. This has inspired research into both elaborate formulations of Probability Theory and alternate interpretations for wave functions. Herein the latter tactic is taken and a suggested variant interpretation of wave functions based on photo detection physics proposed, and some empirical consequences are considered. Although incomplete in a few details, this variant is appealing in its reliance on well tested concepts and technology.

  12. Posterior elbow release and humeral osteotomy for patients with arthrogryposis.

    PubMed

    Zlotolow, Dan A; Kozin, Scott H

    2012-05-01

    Children with arthrogryposis often lack the ability to feed themselves, largely due to limited shoulder external rotation and elbow flexion. Patients who can achieve passive elbow flexion through a surgical release but who cannot externally rotate their shoulders are still unable to reach their mouths with their hands. Combining a posterior elbow capsular release with a simultaneous humeral osteotomy in these patients places the forearm and hand in a much better position for function with minimal additional surgical exposure. PMID:22483178

  13. Posterior dislocation of the hip while playing basketball.

    PubMed

    Tennent, T D; Chambler, A F; Rossouw, D J

    1998-12-01

    Injuries in basketball are usually to the ankles and knees. Dislocation of the hip is usually associated with severe trauma--for example, road traffic accidents. A case is reported here in which a 22 year old club basketball player slipped on landing from a jump shot, forcing him into a side splits position from which he sustained a posterior dislocation of the hip resulting in a sciatic nerve palsy. PMID:9865411

  14. Popliteal artery injury during posterior cruciate ligament reconstruction☆

    PubMed Central

    Cenni, Marcos Henrique Frauendorf; do Nascimento, Bruno Fajardo; Carneiro, Guilherme Galvão Barreto; de Andrade, Rodrigo Cristiano; Pinheiro Júnior, Lúcio Flávio Biondi; Nicolai, Oscar Pinheiro

    2015-01-01

    This study reports a case of popliteal artery injury during arthroscopic reconstruction of the posterior cruciate ligament. The evolution of the injury is described and comments are made regarding the anatomy of this artery and potential risks of this surgical technique. This study had the aims of alerting the medical community, especially knee surgeons, regarding a severe surgical complication and discussing the ways of preventing it. PMID:26229942

  15. Choledochal Cyst with Aberrant Right Posterior Sectoral Duct.

    PubMed

    Singh, Sumitoj; Singh, Narinder Pal; Goyal, Anirudh; Hans, Satpal; Khichy, Sudhir

    2015-12-01

    Choledochal cysts are focal or diffuse dilatations of the biliary tree. Its association with the aberrant hepatic duct is rarely reported. We present the case of a 14-year-old girl having aberrant right posterior sectoral duct with choledochal cyst. It can be missed on cholangiography and during surgery, leading to serious complications. In this case, it was diagnosed on magnetic resonance cholangiopancreatography and was managed along with cyst excision. PMID:26730107

  16. Calculating the CEP (Circular Error Probable)

    NASA Technical Reports Server (NTRS)

    1987-01-01

    This report compares the probability contained in the Circular Error Probable associated with an Elliptical Error Probable to that of the EEP at a given confidence level. The levels examined are 50 percent and 95 percent. The CEP is found to be both more conservative and less conservative than the associated EEP, depending on the eccentricity of the ellipse. The formulas used are derived in the appendix.

  17. A case of nodular posterior scleritis mimicking choroidal mass

    PubMed Central

    Ozkaya, Abdullah; Alagoz, Cengiz; Koc, Alperen; Ozkaya, Hande Mefkure; Yazıcı, Ahmet Taylan

    2014-01-01

    The aim of this study is to report clinical and imaging findings, and treatment outcomes of a patient with nodular posterior scleritis. A 41-year-old woman was diagnosed as nodular posterior scleritis in the light of clinical and imaging findings. At first admission best corrected visual acuity was 20/50 in her right eye. Fundus examination revealed an amelanotic subretinal mass under the superior temporal arcade associated with subretinal fluid surrounding it. B-scan ultrasonography, optical coherence tomography, fluorescein angiography, and indocyanine green angiography findings confirmed the diagnosis. As treatment, nepafenac eye drops 3 times a day, and flurbiprofen tablet 100 mg twice a day were prescribed. After 4 weeks of treatment, the ocular pain was relieved, BCVA improved to 20/20, and subretinal mass totally regressed. Although the diagnosis of nodular posterior scleritis may be confusing, it has to be kept in mind in patients with a subretinal/choroidal mass. Multimodal fundus imaging may be helpful in differential diagnosis. The condition is usually curable with non-steroidal anti-inflammatory drugs and/or systemic steroids. PMID:25892938

  18. A case of nodular posterior scleritis mimicking choroidal mass.

    PubMed

    Ozkaya, Abdullah; Alagoz, Cengiz; Koc, Alperen; Ozkaya, Hande Mefkure; Yazıcı, Ahmet Taylan

    2015-01-01

    The aim of this study is to report clinical and imaging findings, and treatment outcomes of a patient with nodular posterior scleritis. A 41-year-old woman was diagnosed as nodular posterior scleritis in the light of clinical and imaging findings. At first admission best corrected visual acuity was 20/50 in her right eye. Fundus examination revealed an amelanotic subretinal mass under the superior temporal arcade associated with subretinal fluid surrounding it. B-scan ultrasonography, optical coherence tomography, fluorescein angiography, and indocyanine green angiography findings confirmed the diagnosis. As treatment, nepafenac eye drops 3 times a day, and flurbiprofen tablet 100 mg twice a day were prescribed. After 4 weeks of treatment, the ocular pain was relieved, BCVA improved to 20/20, and subretinal mass totally regressed. Although the diagnosis of nodular posterior scleritis may be confusing, it has to be kept in mind in patients with a subretinal/choroidal mass. Multimodal fundus imaging may be helpful in differential diagnosis. The condition is usually curable with non-steroidal anti-inflammatory drugs and/or systemic steroids. PMID:25892938

  19. Automated measurement of anterior and posterior acetabular sector angles

    NASA Astrophysics Data System (ADS)

    Ibragimov, Bulat; Likar, Boštjan; Pernuš, Franjo; Vrtovec, Tomaž

    2012-03-01

    In this paper, we propose a segmentation algorithm by which anatomical landmarks on the pelvis are extracted from computed tomography (CT) images. The landmarks are used to automatically define the anterior (AASA) and posterior acetabular sector angles (PASA) describing the degree of hip misalignment. The center of each femoral head is obtained by searching for the point at which most intensity gradient vectors defined at edge points intersect. The radius of each femoral head is computed by finding the sphere, positioned at the center of the femoral head, for which the normalized sum of gradient vector magnitudes on the sphere surface is maximal. The anterior and posterior corners of each acetabulum are searched for on a curve representing the acetabulum and defined by dynamic programming. The femoral head centers and anterior and posterior corners are used to calculate the AASA and PASA. The algorithm was applied to CT images of 120 normal subjects and the results were compared to ground truth values obtained by manual segmentation. The mean absolute difference (+/- standard deviation) between the obtained and ground truth values was 1.3 +/- 0.3 mm for the femoral head centers and 2.1 +/- 1.3 degrees for the acetabular angles.

  20. Surgery for posterior mediastinal dumbbell tumors: A case report

    PubMed Central

    Mo, Ansheng; Zhang, Jiali

    2015-01-01

    Introduction Mediastinal dumbbell tumors are rare, and special cases provide valuable knowledge to the existing literature. Presentation of case A 57-year-old woman was diagnosed with a recurrent dumbbell-shaped nerve sheath tumor with intrathoracic and intraspinal components. We attempted to resect the tumor via combined biport thoracoscopy and laminectomy with the patient in a prone position. However, copious bleeding prevented complete removal of the intraspinal component of the tumor. Pathological examination of the operative specimens showed a mixed hemangioma. Discussion The first report on the use of triportal thoracoscopy for treatment of a posterior mediastinal dumbbell tumor with the patient in the prone position was published in 1995. However, this technique is not widely used. The technique used in our case is unique only in that biportal rather than triportal thoracoscopy was used to resect the intrathoracic component of the tumor. The differential diagnoses of posterior mediastinal dumbbell-shaped tumors include neurogenic tumors, meningiomas, and hemangiomas. Very rarely, cavernous and capillary hemangiomas also present as dumbbell-shaped lesions. To our knowledge, a mixed hemangioma presenting as a dumbbell-shaped lesion has not been previously reported. Conclusion The intrathoracic component of a posterior mediastinal dumbbell tumor can be resected by biportal thoracoscopy with the patient in a prone position, reducing the operative time. If the diagnosis of a dumbbell tumor is inconclusive, an endoscopic biopsy should be performed before removing the tumor. PMID:26568825

  1. Evaluation of mandibular condyles in children with unilateral posterior crossbite.

    PubMed

    Illipronti-Filho, Edson; Fantini, Solange Mongelli de; Chilvarquer, Israel

    2015-01-01

    The relationship of mandibular condyle dimensions and its association with unilateral posterior crossbite (UPXB) has been suggested in the literature. The purpose of this prospective study was to evaluate mandibular condyles on the left and right sides and between crossed and non-crossed sides in the sagittal and coronal planes, using cone-beam computed tomography (CBCT). Twenty CBCT images of 40 temporo mandibular joints (TMJs) in individuals in mixed dentition phase, which included 9 males (mean 7.9 years) and 11 females (mean 8.2 years), with unilateral posterior crossbite without premature contacts and functional mandibular shifts and with transverse maxillary deficiency. The criteria for sample exclusion included the presence of painful symptoms, facial trauma history, systemic diseases such as juvenile rheumatoid arthritis, mouth opening limitation (< 40 mm), congenital or genetic anomalies, and skeletal asymmetries that may result in TMJ disorders. Dimensional measurements of the condyles between the right and left sides and crossed and non-crossed sides in sagittal and coronal view were made. There was no significant difference between the measurements of the crossed and non-crossed sides in both sagittal and coronal view. These findings suggest that the presence of unilateral posterior crossbite in children with UPXB did not result in changes between the mandibular condyles in the right and left sides or between the crossed and non-crossed sides in the coronal or sagittal plane. PMID:25760067

  2. Anterior-posterior regionalized gene expression in the Ciona notochord

    PubMed Central

    Veeman, Michael

    2014-01-01

    Background In the simple ascidian chordate Ciona the signaling pathways and gene regulatory networks giving rise to initial notochord induction are largely understood and the mechanisms of notochord morphogenesis are being systematically elucidated. The notochord has generally been thought of as a non-compartmentalized or regionalized organ that is not finely patterned at the level of gene expression. Quantitative imaging methods have recently shown, however, that notochord cell size, shape and behavior vary consistently along the anterior-posterior (AP) axis. Results Here we screen candidate genes by whole mount in situ hybridization for potential AP asymmetry. We identify 4 genes that show non-uniform expression in the notochord. Ezrin/radixin/moesin (ERM) is expressed more strongly in the secondary notochord lineage than the primary. CTGF is expressed stochastically in a subset of notochord cells. A novel calmodulin-like gene (BCamL) is expressed more strongly at both the anterior and posterior tips of the notochord. A TGF-β ortholog is expressed in a gradient from posterior to anterior. The asymmetries in ERM, BCamL and TGF-β expression are evident even before the notochord cells have intercalated into a single-file column. Conclusions We conclude that the Ciona notochord is not a homogeneous tissue but instead shows distinct patterns of regionalized gene expression. PMID:24288133

  3. Intensity-Modulated Arc Therapy for Pediatric Posterior Fossa Tumors

    SciTech Connect

    Beltran, Chris; Gray, Jonathan; Merchant, Thomas E.

    2012-02-01

    Purpose: To compare intensity-modulated arc therapy (IMAT) to noncoplanar intensity-modulated radiation therapy (IMRT) in the treatment of pediatric posterior fossa tumors. Methods and Materials: Nine pediatric patients with posterior fossa tumors, mean age 9 years (range, 6-15 years), treated using IMRT were chosen for this comparative planning study because of their tumor location. Each patient's treatment was replanned to receive 54 Gy to the planning target volume (PTV) using five different methods: eight-field noncoplanar IMRT, single coplanar IMAT, double coplanar IMAT, single noncoplanar IMAT, and double noncoplanar IMAT. For each method, the dose to 95% of the PTV was held constant, and the doses to surrounding critical structures were minimized. The different plans were compared based on conformity, total linear accelerator dose monitor units, and dose to surrounding normal tissues, including the entire body, whole brain, temporal lobes, brainstem, and cochleae. Results: The doses to the target and critical structures for the various IMAT methods were not statistically different in comparison with the noncoplanar IMRT plan, with the following exceptions: the cochlear doses were higher and whole brain dose was lower for coplanar IMAT plans; the cochleae and temporal lobe doses were lower and conformity increased for noncoplanar IMAT plans. The advantage of the noncoplanar IMAT plan was enhanced by doubling the treatment arc. Conclusion: Noncoplanar IMAT results in superior treatment plans when compared to noncoplanar IMRT for the treatment of posterior fossa tumors. IMAT should be considered alongside IMRT when treatment of this site is indicated.

  4. Consolidation of Complex Events via Reinstatement in Posterior Cingulate Cortex.

    PubMed

    Bird, Chris M; Keidel, James L; Ing, Leslie P; Horner, Aidan J; Burgess, Neil

    2015-10-28

    It is well-established that active rehearsal increases the efficacy of memory consolidation. It is also known that complex events are interpreted with reference to prior knowledge. However, comparatively little attention has been given to the neural underpinnings of these effects. In healthy adults humans, we investigated the impact of effortful, active rehearsal on memory for events by showing people several short video clips and then asking them to recall these clips, either aloud (Experiment 1) or silently while in an MRI scanner (Experiment 2). In both experiments, actively rehearsed clips were remembered in far greater detail than unrehearsed clips when tested a week later. In Experiment 1, highly similar descriptions of events were produced across retrieval trials, suggesting a degree of semanticization of the memories had taken place. In Experiment 2, spatial patterns of BOLD signal in medial temporal and posterior midline regions were correlated when encoding and rehearsing the same video. Moreover, the strength of this correlation in the posterior cingulate predicted the amount of information subsequently recalled. This is likely to reflect a strengthening of the representation of the video's content. We argue that these representations combine both new episodic information and stored semantic knowledge (or "schemas"). We therefore suggest that posterior midline structures aid consolidation by reinstating and strengthening the associations between episodic details and more generic schematic information. This leads to the creation of coherent memory representations of lifelike, complex events that are resistant to forgetting, but somewhat inflexible and semantic-like in nature. PMID:26511235

  5. Differential cerebrovascular CO₂ reactivity in anterior and posterior cerebral circulations.

    PubMed

    Skow, Rachel J; MacKay, Christina M; Tymko, Michael M; Willie, Christopher K; Smith, Kurt J; Ainslie, Philip N; Day, Trevor A

    2013-10-01

    The potential differences in cerebrovascular responses between the anterior and posterior circulations to changes in CO₂ are unclear in humans. Using transcranial Doppler ultrasound, we compared the CO₂ reactivity of the (1) BA and PCA and (2) MCA and PCA during hyperoxic rebreathing in supine position. The reactivity in the BA and PCA was similar in both absolute (1.27 ± 0.5 and 1.27 ± 0.6 cm/s/Torr; P=0.992) and relative (3.98 ± 1.3 and 3.66 ± 1.5%/Torr CO2; P=0.581) measures, suggesting that the PCA is an adequate surrogate measure of reactivity for the BA. The MCA reactivity was greater than the PCA in absolute (2.09 ± 0.7 and 1.22 ± 0.5 cm/s/Torr CO₂; P<0.001), but not relative measures (3.25 ± 1.0 and 3.56 ± 1.6%/Torr CO₂; P=0.629). Our findings (a) confirm regional differences in the absolute reactivity in the human brain and (b) suggest that in cerebrovascular studies investigating functions mediated by posterior brain structures (e.g., control of breathing), the posterior vasculature should also be insonated. PMID:23774143

  6. Macular Development in Aggressive Posterior Retinopathy of Prematurity

    PubMed Central

    Pandya, Hemang K.; Faia, Lisa J.; Robinson, Joshua; Drenser, Kimberly A.

    2015-01-01

    Purpose. To report anatomic outcomes after early and confluent laser photocoagulation of the entire avascular retina, including areas in close proximity to the fovea, in patients with APROP. We aspire to demonstrate fundoscopic evidence of transverse growth and macular development following laser treatment in APROP. Methods. Retrospective review of 6 eyes with APROP that underwent confluent laser photocoagulation of the entire avascular retina. Photographic fundoscopic imaging was performed using the RetCam to compare outcomes after treatment. Results. Mean birth weight and gestational age were 704.8?g and 24.33 weeks, respectively. There were 2 females and 1 male. The average time to laser was 9.3 weeks after birth, with the mean postmenstrual age of 34 weeks. Two eyes had zone 1 and 4 eyes had posterior zone 2 disease. Three eyes developed 4A detachments, which were successfully treated. All 6 eyes experienced transverse growth, with expansion of the posterior pole and anterior displacement of the laser treatment. Conclusion. Confluent photocoagulation of the entire avascular retina, regardless of foveal proximity, should be the mainstay for treating APROP. Examination should be conducted within 510 days to examine areas previously hidden by neovascularization to ensure prudent therapy. Macular development involves both transverse and anterior-posterior growth. PMID:26167498

  7. Anterior-posterior beta asymmetries in dyslexia during lexical decisions.

    PubMed

    Duncan Milne, R; Hamm, Jeff P; Kirk, Ian J; Corballis, Michael C

    2003-03-01

    High-density EEG was recorded in 12 compensated dyslexics, 6 classified as dysphonetic and 6 as dyseidetic, and in 12 matched controls while they carried out a lexical-decision task. Relative to normal controls, dysphonetics showed higher beta power in anterior relative to posterior regions, while dyseidetics showed higher beta power in posterior relative to anterior regions. Further, controls (but not dyslexics) showed a positive correlation between performance on the task and the ratios of both left-to-right and anterior-to-posterior beta asymmetry. According to the dual-route theory of reading, there are two strategies that can be used in lexical decision: A visual strategy involving visual word identification and direct access to a visual lexicon, and a phonological strategy involving grapheme-to-phoneme conversion and access to a speech output lexicon. Our results therefore suggest compensation through weakness rather than strength, with phonological dyslexics focusing on a grapheme-to-phoneme strategy and dyseidetics focusing on visual word identification. PMID:12662973

  8. Mitomycin against posterior capsular opacification: an experimental study in rabbits.

    PubMed Central

    Haus, C M; Galand, A L

    1996-01-01

    AIMS/BACKGROUND: Posterior capsular opacification is the most common postoperative complication of extracapsular cataract surgery. The purpose of this study was to attempt to inhibit this secondary cataract formation by using mitomycin (an antimitotic drug). METHODS: A solution containing mitomycin was used to perform hydrodissection (with a 5 minute pause) during extracapsular lens extraction in rabbits. This way of administration was chosen to reduce as much as possible drug diffusion into the anterior chamber. Heparin was added to the irrigating solution to avoid fibrin formation. Its ability to prevent posterior cataract opacification was also evaluated at the end of the study. The animals were sacrificed 4 or 6 months after surgery. Grading concerning two aspects of secondary cataract (proliferation and fibrosis) was obtained on gross examination. Histological analysis was subsequently performed. RESULTS: This study demonstrated that mitomycin has a significant inhibitory effect on secondary cataract formation (proliferation as well as fibrosis) in rabbits whereas heparin does not seem to have the same effectiveness. CONCLUSION: This work is a preliminary study concerning the use of mitomycin for prevention of posterior capsular opacification. It has proved its effectiveness in rabbits but more in depth studies are still necessary before its application in humans. Images PMID:9059276

  9. Posterior minimally invasive plate osteosynthesis for humeral shaft fractures.

    PubMed

    Gallucci, Gerardo; Boretto, Jorge; Vujovich, Andrea; Alfie, Verónica; Donndorff, Agustín; De Carli, Pablo

    2014-03-01

    Fractures of the humeral shaft are common. Most of them can be successfully treated without surgery. In some cases, an operative intervention may offer faster and better functional results. One of the major problems with the open plating osteosynthesis is the extensive soft tissue stripping and disruption of periosteal circulation, caused by extensive surgical exposure, resulting in a relatively high rate of nonunion. Minimally invasive plate osteosynthesis (MIPO) techniques were developed to achieve a biologic fixation, although minimizing the complications of an open reduction. The incisions are small and remote from the fracture site to avoid direct fracture exposure. Thereby, MIPO technique obtains, theoretically, higher rates of union, lower infection risk, and decreases the need for bone graft. In the last years, MIPO has gained popularity with satisfactory clinical outcomes in the treatment of long bone fractures, especially in lower extremity. MIPO for humeral shaft fractures, however, could be a surgically dangerous procedure because of the risk of radial nerve injury. It was described by anterior and lateral approach. Humeral middle shaft fractures are possible to treat with a MIPO technique through an anterior, lateral, or a posterior approach. However, when the fracture is near the olecranon fossa, anterior approach is not possible as there is not enough space in the distal fragment to insert the amount of screws required to achieve stability. In this case, the posterior approach may be a good option for treatment. This article describes the MIPO technique through a posterior approach for the treatment of humeral shaft fractures. PMID:24458002

  10. Effect of four different intraocular lenses on posterior capsule opacification

    PubMed Central

    Duman, Rahmi; Karel, Fatih; Özyol, Pelin; Ateş, Can

    2015-01-01

    AIM To evaluate the impact of 4 different intraocular lenses (IOLs) on posterior capsule opacification (PCO) by comparing the neodymium: yttrium-aluminum-garnet (Nd:YAG) laser capsulotomy rates. METHODS This retrospective study included 4970 eyes of 4013 cataract patients who underwent phacoemulsification and IOL implantation between January 2000 and January 2008 by the same surgeon at one clinic. Four different IOLs were assessed. The outcome parameter was the incidence of Nd:YAG laser posterior capsulotomies. RESULTS An Nd:YAG laser posterior capsulotomy was performed in 153 (3.07%) of the 4970 eyes. The mean follow-up time was 84mo for all of the IOL groups. The percentage of eyes developing PCO was significantly greater for the acrylic hydrophilic IOLs than for the hydrophobic IOLs, although eyes with acrylic hydrophilic IOLs did not require Nd:YAG laser capsulotomy as soon as eyes with acrylic hydrophobic IOLs. There was no difference between the long-term PCO rates when 1- and 3-piece acrylic hydrophobic IOLs were compared or when IOLs made of the same material but with different haptic angles were compared. CONCLUSION In this study, eyes with acrylic hydrophilic IOLs were more likely to develop PCO than those with acrylic hydrophobic IOLs. The lens design (1-piece versus 3-piece and varying haptic angles) did not affect the PCO rate. PMID:25709920

  11. Evaluating pathogenic dementia variants in posterior cortical atrophy.

    PubMed

    Carrasquillo, Minerva M; Barber, Imelda; Lincoln, Sarah J; Murray, Melissa E; Camsari, Gamze Balci; Khan, Qurat ul Ain; Nguyen, Thuy; Ma, Li; Bisceglio, Gina D; Crook, Julia E; Younkin, Steven G; Dickson, Dennis W; Boeve, Bradley F; Graff-Radford, Neill R; Morgan, Kevin; Ertekin-Taner, Nilüfer

    2016-01-01

    Posterior cortical atrophy (PCA) is an understudied visual impairment syndrome most often due to "posterior Alzheimer's disease (AD)" pathology. Case studies detected mutations in PSEN1, PSEN2, GRN, MAPT, and PRNP in subjects with clinical PCA. To detect the frequency and spectrum of mutations in known dementia genes in PCA, we screened 124 European-American subjects with clinical PCA (n = 67) or posterior AD neuropathology (n = 57) for variants in genes implicated in AD, frontotemporal dementia, and prion disease using NeuroX, a customized exome array. Frequencies in PCA of the variants annotated as pathogenic or potentially pathogenic were compared against ∼ 4300 European-American population controls from the NHLBI Exome Sequencing Project. We identified 2 rare variants not previously reported in PCA, TREM2 Arg47His, and PSEN2 Ser130Leu. No other pathogenic or potentially pathogenic variants were detected in the screened dementia genes. In this first systematic variant screen of a PCA cohort, we report 2 rare mutations in TREM2 and PSEN2, validate our previously reported APOE ε4 association, and demonstrate the utility of NeuroX. PMID:26507310

  12. Rapid Visual Deterioration Caused by Posterior Fossa Arachnoid Cyst

    PubMed Central

    Shin, Chang Jin; Rho, Myeongho; Won, Yu Sam

    2016-01-01

    Posterior fossa is a site next to the middle fossa where arachnoid cyst frequently occurs. Generally, most arachnoid cysts are asymptomatic and are found incidentally in most cases. Although arachnoid cysts are benign and asymptomatic lesions, patients with posterior fossa arachnoid cysts often complain of headaches, gait disturbance, and ataxia due to the local mass effects on the cerebellum. We observed a patient with a posterior fossa arachnoid cyst who had visual symptoms and a headache, but did not have gait disturbance and ataxia. We recommended an emergency operation for decompression, but the patient refused for personal reasons. After 7 days, the patient revisited our hospital in a state of near-blindness. We suspected that the arachnoid cyst induced the hydrocephalus and thereby the enlarged third ventricle directly compressed optic nerves. Compressed optic nerves were rapidly aggravated during the critical seven days; consequently, the patient's vision was damaged despite the operation. Considering the results of our case, it is important to keep in mind that the aggravation of symptoms cannot be predicted; therefore, symptomatic arachnoid cysts should be treated without undue delay. PMID:27226868

  13. The Great Imitator: Ocular Syphilis Presenting as Posterior Uveitis

    PubMed Central

    Kuo, Alan; Ziaee, Saba M.; Hosseini, Hamid; Voleti, Vinod; Schwartz, Steven D.; Kim, Nam U.; Ge, Phillip S.

    2015-01-01

    Patient: Female, 34 Final Diagnosis: Ocular syphilis Symptoms: Painful unilateral vision loss Medication: Benzylpenicillin Clinical Procedure: Lumbar puncture Specialty: Infectious Diseases • Ophthalmology Objective: Rare disease Background: Syphilis is often known as the “Great Imitator”. The differential diagnosis of posterior uveitis is broad with ocular syphilis being particularly challenging to diagnose as it presents similarly to other ocular conditions such as acute retinal necrosis. Case Report: A 34-year-old woman with multiple sexual partners over the past few years presented with painful and progressively worsening unilateral vision loss for 2 weeks. Several months prior, she had reported non-specific symptoms of headache and diffuse skin rash. Despite treatment with oral acyclovir for 3 weeks, her vision progressively declined, and she was referred to the university ophthalmology clinic for further evaluation. On examination, there was concern for acute retinal necrosis and she was empirically treated with parenteral acyclovir while awaiting further infectious disease study results. Workup ultimately revealed ocular syphilis, and neurosyphilis was additionally confirmed with cerebrospinal fluid studies. Treatment with intravenous penicillin was promptly initiated with complete visual recovery. Conclusions: Ocular syphilis varies widely in presentation and should be considered in all patients with posterior uveitis, especially with a history of headache and skin rashes. However, given that acute retinal necrosis is a more common cause of posterior uveitis and can rapidly result in permanent vision loss, it should be empirically treated whenever it is suspected while simultaneous workup is conducted to evaluate for alternative diagnoses. PMID:26151369

  14. Is probability of frequency too narrow?

    SciTech Connect

    Martz, H.F.

    1993-10-01

    Modern methods of statistical data analysis, such as empirical and hierarchical Bayesian methods, should find increasing use in future Probabilistic Risk Assessment (PRA) applications. In addition, there will be a more formalized use of expert judgment in future PRAs. These methods require an extension of the probabilistic framework of PRA, in particular, the popular notion of probability of frequency, to consideration of frequency of frequency, frequency of probability, and probability of probability. The genesis, interpretation, and examples of these three extended notions are discussed.

  15. Psychophysics of the probability weighting function

    NASA Astrophysics Data System (ADS)

    Takahashi, Taiki

    2011-03-01

    A probability weighting function w(p) for an objective probability p in decision under risk plays a pivotal role in Kahneman-Tversky prospect theory. Although recent studies in econophysics and neuroeconomics widely utilized probability weighting functions, psychophysical foundations of the probability weighting functions have been unknown. Notably, a behavioral economist Prelec (1998) [4] axiomatically derived the probability weighting function w(p)=exp(-() (0<α<1 and w(0)=1,w(1e)=1e,w(1)=1), which has extensively been studied in behavioral neuroeconomics. The present study utilizes psychophysical theory to derive Prelec's probability weighting function from psychophysical laws of perceived waiting time in probabilistic choices. Also, the relations between the parameters in the probability weighting function and the probability discounting function in behavioral psychology are derived. Future directions in the application of the psychophysical theory of the probability weighting function in econophysics and neuroeconomics are discussed.

  16. What Are the Odds? Constructing Competition Probabilities.

    ERIC Educational Resources Information Center

    Brazier, Gerald D.

    1980-01-01

    A model of competition probabilities using past performances of competitors against common opponents is constructed. Application to predicting victories in athletic competitions is also reviewed. (MP)

  17. What you need to know about ossification of the posterior longitudinal ligament to optimize cervical spine surgery: A review

    PubMed Central

    Epstein, Nancy E.

    2014-01-01

    What are the risks, benefits, alternatives, and pitfalls for operating on cervical ossification of the posterior longitudinal ligament (OPLL)? To successfully diagnose OPLL, it is important to obtain Magnetic Resonance Images (MR). These studies, particularly the T2 weighted images, provide the best soft-tissue documentation of cord/root compression and intrinsic cord abnormalities (e.g. edema vs. myelomalacia) on sagittal, axial, and coronal views. Obtaining Computed Tomographic (CT) scans is also critical as they best demonstrate early OPLL, or hypertrophied posterior longitudinal ligament (HPLL: hypo-isodense with punctate ossification) or classic (frankly ossified) OPLL (hyperdense). Furthermore, CT scans reveal the “single layer” and “double layer” signs indicative of OPLL penetrating the dura. Documenting the full extent of OPLL with both MR and CT dictates whether anterior, posterior, or circumferential surgery is warranted. An adequate cervical lordosis allows for posterior cervical approaches (e.g. lamionplasty, laminectomy/fusion), which may facilitate addressing multiple levels while avoiding the risks of anterior procedures. However, without lordosis and with significant kyphosis, anterior surgery may be indicated. Rarely, this requires single/multilevel anterior cervical diskectomy/fusion (ACDF), as this approach typically fails to address retrovertebral OPLL; single or multilevel corpectomies are usually warranted. In short, successful OPLL surgery relies on careful patient selection (e.g. assess comorbidities), accurate MR/CT documentation of OPLL, and limiting the pros, cons, and complications of these complex procedures by choosing the optimal surgical approach. Performing OPLL surgery requires stringent anesthetic (awake intubation/positioning) and also the following intraoperative monitoring protocols: Somatosensory evoked potentials (SSEP), motor evoked potentials (MEP), and electromyography (EMG). PMID:24843819

  18. Determination of Highly Accurate Heats of Formation

    NASA Technical Reports Server (NTRS)

    Lee, Timothy J.; Langhoff, Stephen R. (Technical Monitor)

    1996-01-01

    Two approaches for directly computing a molecular heat of formation based on sophisticated ab initio electronic structure theory axe discussed and example calculations are presented for several molecules of interest in atmospheric chemistry including HNO and CICN. The accuracy of these approaches for a small subset of the molecules is demonstrated by comparison to very accurate experimental data. A third approach for evaluating accurate heats of formation consists of combining experimental and theoretical data. The potential for this method to provide reliable thermochemical data on many molecules using accurate experimental beats of formation for only a small number of species is demonstrated by giving accurate (Delta)H(sup 0, sub f) quantities for a host of fluorine, chlorine, and bromine oxide and nitrogen oxide compounds. Potential pitfalls in all three approaches are discussed.

  19. Remote balance weighs accurately amid high radiation

    NASA Technical Reports Server (NTRS)

    Eggenberger, D. N.; Shuck, A. B.

    1969-01-01

    Commercial beam-type balance, modified and outfitted with electronic controls and digital readout, can be remotely controlled for use in high radiation environments. This allows accurate weighing of breeder-reactor fuel pieces when they are radioactively hot.

  20. Mill profiler machines soft materials accurately

    NASA Technical Reports Server (NTRS)

    Rauschl, J. A.

    1966-01-01

    Mill profiler machines bevels, slots, and grooves in soft materials, such as styrofoam phenolic-filled cores, to any desired thickness. A single operator can accurately control cutting depths in contour or straight line work.

  1. Accurate control of contrast on microcomputer displays.

    PubMed

    Pelli, D G; Zhang, L

    1991-01-01

    Off-the-shelf microcomputers can now display arbitrary 8-bit images, but accurate control of these images requires dealing with several undesirable properties of real digital to analog converters (DACs) and analog video monitors. The limitations of DACs and video monitors are presented in the form of a model for their calibration and use in vision experiments. Low contrasts can be accurately rendered by summing a small accurate a.c. signal and a large less-accurate d.c. signal (Watson et al., 1986; Behavior Research, Method, Instrument and Computers, 18, 587-594). Exploiting that idea, this note presents an easy-to-build passive resistor network, a video attenuator, that combines the outputs of three 8-bit DACs to render low contrasts with 12-bit accuracy at the display. Measurements confirm the 12-bit accuracy. PMID:1891822

  2. Posterior corneal curvature changes following Refractive Small Incision Lenticule Extraction

    PubMed Central

    Ganesh, Sri; Patel, Utsav; Brar, Sheetal

    2015-01-01

    Purpose To compare the posterior corneal curvature changes, in terms of corneal power and asphercity, following Refractive Small Incision Lenticule Extraction (ReLEx SMILE) procedure for low, moderate, and high myopia. Methods This retrospective, non randomized, comparative, interventional trial; included 52 eyes of 26 patients, divided in three groups: low myopia (myopia ≤3 D [diopters] spherical equivalent [SE]), moderate myopia (myopia >3 D and <6 D SE), and high myopia (myopia ≥6 D SE). All patients were treated for myopia and myopic astigmatism using ReLEx SMILE. The eyes were examined pre-operatively and 3 months post-operatively using SCHWIND SIRIUS, a three-dimensional rotating Scheimpflug camera with a Placido disc topographer to assess corneal changes with regard to keratometric power and asphericity of the cornea. Results A statistically significant increase in mean keratometric power in the 3, 5, and 7 mm zones of the posterior corneal surface compared with its pre-ReLEx SMILE value was detected after 3 months in the moderate myopia group (pre-operative [pre-op] −6.14±0.23, post-operative [post-op] −6.29±0.22, P<0.001) and high myopia group (pre-op −6.19±0.16, post-op −6.4±0.18, P<0.001), but there was no significant change in keratometric power of the posterior surface in the low myopia group (pre-op −5.87±0.17, post-op −6.06±0.29, P=0.143). Asphericity (Q-value) of the posterior surface changed significantly (P<0.001) after ReLEx SMILE in the moderate myopia group in the 3, 5, and 7 mm zones, and in the high myopia group in the 3 and 7 mm zones; but there was no significant change in the Q-value in the low myopia group in all three zones (pre-op 0.23±0.43, post-op −0.40±0.71, P=0.170), and in the high myopia group in the 5 mm zone (P=0.228). Conclusion ReLEx SMILE causes significant changes in posterior corneal keratometric power and asphericity in moderate and high myopia, but the effect is subtle and insignificant in low myopia. PMID:26229428

  3. Arthroscopic posterior cruciate ligament reconstruction with allograft versus autograft

    PubMed Central

    Sun, Xiujiang; Zhang, Jianfeng; Qu, Xiaoyi

    2015-01-01

    Introduction The aim of the study was to compare and analyze retrospectively the outcomes of arthroscopic posterior cruciate ligament reconstruction with autograft versus allograft. Material and methods Seventy-one patients who underwent arthroscopic posterior cruciate ligament reconstruction with an autograft or allograft met our inclusion criteria. There were 36 patients in the autograft group and 35 patients in the allograft group. All the patients were evaluated by physical examination and a functional ligament test. Comparative analysis was done in terms of operation time, incision length, fever time, postoperative infection rate, incidence of numbness and dysesthesia around the incision, as well as a routine blood test. Results The average follow-up of the autograft group was 3.2 ±0.2 years and that of the allograft group was 3.3 ±0.6 years; there was no significant difference (p > 0.05). No differences existed in knee range of motion, Lysholm scores, International Knee Documentation Committee standard evaluation form and Tegner activity score at final follow-up (p > 0.05), except that patients in the allograft group had a shorter operation time and incision length and a longer fever time (p < 0.05). We found a difference in posterior drawer test and KT-2000 arthrometer assessment (p < 0.05). The posterior tibia displacement averaged 3.8 ±1.5 mm in the autograft group and 4.8 ±1.7 mm in the allograft group (p < 0.05). The incidence of numbness and dysesthesia around the incision in the autograft group was higher than that in the allograft group (p < 0.05). There was no infection postoperatively. The white blood cells and neutrophils in the allograft group increased more than those in the autograft group postoperatively (p < 0.05). Conclusions Both groups of patients had satisfactory outcomes after the operation. However, in the instrumented posterior laxity test, the autograft gave better results than the allograft. No differences in functional scores were found. PMID:25995757

  4. Understanding the Code: keeping accurate records.

    PubMed

    Griffith, Richard

    2015-10-01

    In his continuing series looking at the legal and professional implications of the Nursing and Midwifery Council's revised Code of Conduct, Richard Griffith discusses the elements of accurate record keeping under Standard 10 of the Code. This article considers the importance of accurate record keeping for the safety of patients and protection of district nurses. The legal implications of records are explained along with how district nurses should write records to ensure these legal requirements are met. PMID:26418404

  5. Sensitivity Analysis and Assessment of Prior Model Probabilities in MLBMA with Application to Unsaturated Fractured Tuff

    SciTech Connect

    Ye, Ming; Neuman, Shlomo P.; Meyer, Philip D.; Pohlmann, Karl

    2005-12-24

    Previous application of Maximum Likelihood Bayesian Model Averaging (MLBMA, Neuman [2002, 2003]) to alternative variogram models of log air permeability data in fractured tuff has demonstrated its effectiveness in quantifying conceptual model uncertainty and enhancing predictive capability [Ye et al., 2004]. A question remained how best to ascribe prior probabilities to competing models. In this paper we examine the extent to which lead statistics of posterior log permeability predictions are sensitive to prior probabilities of seven corresponding variogram models. We then explore the feasibility of quantifying prior model probabilities by (a) maximizing Shannon's entropy H [Shannon, 1948] subject to constraints reflecting a single analyst's (or a group of analysts?) prior perception about how plausible each alternative model (or a group of models) is relative to others, and (b) selecting a posteriori the most likely among such maxima corresponding to alternative prior perceptions of various analysts or groups of analysts. Another way to select among alternative prior model probability sets, which however is not guaranteed to yield optimum predictive performance (though it did so in our example) and would therefore not be our preferred option, is a min-max approach according to which one selects a priori the set corresponding to the smallest value of maximum entropy. Whereas maximizing H subject to the prior perception of a single analyst (or group) maximizes the potential for further information gain through conditioning, selecting the smallest among such maxima gives preference to the most informed prior perception among those of several analysts (or groups). We use the same variogram models and log permeability data as Ye et al. [2004] to demonstrate that our proposed approach yields the least amount of posterior entropy (residual uncertainty after conditioning) and enhances predictive model performance as compared to (a) the non-informative neutral case in which all prior model probabilities are set equal to each other and (b) an informed case that nevertheless violates the principle of parsimony.

  6. WPE: A Mathematical Microworld for Learning Probability

    ERIC Educational Resources Information Center

    Kiew, Su Ding; Sam, Hong Kian

    2006-01-01

    In this study, the researchers developed the Web-based Probability Explorer (WPE), a mathematical microworld and investigated the effectiveness of the microworld's constructivist learning environment in enhancing the learning of probability and improving students' attitudes toward mathematics. This study also determined the students' satisfaction…

  7. Probability Issues in without Replacement Sampling

    ERIC Educational Resources Information Center

    Joarder, A. H.; Al-Sabah, W. S.

    2007-01-01

    Sampling without replacement is an important aspect in teaching conditional probabilities in elementary statistics courses. Different methods proposed in different texts for calculating probabilities of events in this context are reviewed and their relative merits and limitations in applications are pinpointed. An alternative representation of…

  8. Teaching Statistics and Probability: 1981 Yearbook.

    ERIC Educational Resources Information Center

    Shulte, Albert P., Ed.; Smart, James R., Ed.

    This 1981 yearbook of the National Council of Teachers of Mathematics (NCTM) offers classroom ideas for teaching statistics and probability, viewed as important topics in the school mathematics curriculum. Statistics and probability are seen as appropriate because they: (1) provide meaningful applications of mathematics at all levels; (2) provide…

  9. 47 CFR 1.1623 - Probability calculation.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 1 2010-10-01 2010-10-01 false Probability calculation. 1.1623 Section 1.1623 Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL PRACTICE AND PROCEDURE Random Selection Procedures for Mass Media Services General Procedures § 1.1623 Probability calculation. (a) All calculations shall...

  10. Teaching Probability: A Socio-Constructivist Perspective

    ERIC Educational Resources Information Center

    Sharma, Sashi

    2015-01-01

    There is a considerable and rich literature on students' misconceptions in probability. However, less attention has been paid to the development of students' probabilistic thinking in the classroom. This paper offers a sequence, grounded in socio-constructivist perspective for teaching probability.

  11. Phonotactic Probabilities in Young Children's Speech Production

    ERIC Educational Resources Information Center

    Zamuner, Tania S.; Gerken, Louann; Hammond, Michael

    2004-01-01

    This research explores the role of phonotactic probability in two-year-olds' production of coda consonants. Twenty-nine children were asked to repeat CVC non-words that were used as labels for pictures of imaginary animals. The CVC non-words were controlled for their phonotactic probabilities, neighbourhood densities, word-likelihood ratings, and…

  12. 47 CFR 1.1623 - Probability calculation.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 1 2013-10-01 2013-10-01 false Probability calculation. 1.1623 Section 1.1623 Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL PRACTICE AND PROCEDURE Grants by Random Selection Random Selection Procedures for Mass Media Services General Procedures § 1.1623 Probability calculation. (a)...

  13. 47 CFR 1.1623 - Probability calculation.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 1 2011-10-01 2011-10-01 false Probability calculation. 1.1623 Section 1.1623 Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL PRACTICE AND PROCEDURE Random Selection Procedures for Mass Media Services General Procedures § 1.1623 Probability calculation. (a) All calculations shall...

  14. 47 CFR 1.1623 - Probability calculation.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 1 2012-10-01 2012-10-01 false Probability calculation. 1.1623 Section 1.1623 Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL PRACTICE AND PROCEDURE Grants by Random Selection Random Selection Procedures for Mass Media Services General Procedures § 1.1623 Probability calculation. (a)...

  15. Simulations of Probabilities for Quantum Computing

    NASA Technical Reports Server (NTRS)

    Zak, M.

    1996-01-01

    It has been demonstrated that classical probabilities, and in particular, probabilistic Turing machine, can be simulated by combining chaos and non-LIpschitz dynamics, without utilization of any man-made devices (such as random number generators). Self-organizing properties of systems coupling simulated and calculated probabilities and their link to quantum computations are discussed.

  16. Laboratory-Tutorial Activities for Teaching Probability

    ERIC Educational Resources Information Center

    Wittmann, Michael C.; Morgan, Jeffrey T.; Feeley, Roger E.

    2006-01-01

    We report on the development of students' ideas of probability and probability density in a University of Maine laboratory-based general education physics course called "Intuitive Quantum Physics". Students in the course are generally math phobic with unfavorable expectations about the nature of physics and their ability to do it. We describe a…

  17. WPE: A Mathematical Microworld for Learning Probability

    ERIC Educational Resources Information Center

    Kiew, Su Ding; Sam, Hong Kian

    2006-01-01

    In this study, the researchers developed the Web-based Probability Explorer (WPE), a mathematical microworld and investigated the effectiveness of the microworld's constructivist learning environment in enhancing the learning of probability and improving students' attitudes toward mathematics. This study also determined the students' satisfaction

  18. Laboratory-Tutorial Activities for Teaching Probability

    ERIC Educational Resources Information Center

    Wittmann, Michael C.; Morgan, Jeffrey T.; Feeley, Roger E.

    2006-01-01

    We report on the development of students' ideas of probability and probability density in a University of Maine laboratory-based general education physics course called "Intuitive Quantum Physics". Students in the course are generally math phobic with unfavorable expectations about the nature of physics and their ability to do it. We describe a

  19. Average Transmission Probability of a Random Stack

    ERIC Educational Resources Information Center

    Lu, Yin; Miniatura, Christian; Englert, Berthold-Georg

    2010-01-01

    The transmission through a stack of identical slabs that are separated by gaps with random widths is usually treated by calculating the average of the logarithm of the transmission probability. We show how to calculate the average of the transmission probability itself with the aid of a recurrence relation and derive analytical upper and lower…

  20. Probability Simulations by Non-Lipschitz Chaos

    NASA Technical Reports Server (NTRS)

    Zak, Michail

    1996-01-01

    It has been demonstrated that classical probabilities, and in particular, probabilistic Turing machine, can be simulated by combining chaos and non-Lipschitz dynamics, without utilization of any man-made devices. Self-organizing properties of systems coupling simulated and calculated probabilities and their link to quantum computations are discussed.

  1. 21 CFR 872.3900 - Posterior artificial tooth with a metal insert.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Posterior artificial tooth with a metal insert... SERVICES (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Prosthetic Devices § 872.3900 Posterior artificial tooth with a metal insert. (a) Identification. A posterior artificial tooth with a metal insert is...

  2. 21 CFR 872.3900 - Posterior artificial tooth with a metal insert.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Posterior artificial tooth with a metal insert... SERVICES (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Prosthetic Devices § 872.3900 Posterior artificial tooth with a metal insert. (a) Identification. A posterior artificial tooth with a metal insert is...

  3. 21 CFR 872.3900 - Posterior artificial tooth with a metal insert.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Posterior artificial tooth with a metal insert... SERVICES (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Prosthetic Devices § 872.3900 Posterior artificial tooth with a metal insert. (a) Identification. A posterior artificial tooth with a metal insert is...

  4. 21 CFR 872.3900 - Posterior artificial tooth with a metal insert.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Posterior artificial tooth with a metal insert... SERVICES (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Prosthetic Devices § 872.3900 Posterior artificial tooth with a metal insert. (a) Identification. A posterior artificial tooth with a metal insert is...

  5. 21 CFR 872.3900 - Posterior artificial tooth with a metal insert.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Posterior artificial tooth with a metal insert... SERVICES (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Prosthetic Devices § 872.3900 Posterior artificial tooth with a metal insert. (a) Identification. A posterior artificial tooth with a metal insert is...

  6. 21 CFR 886.4392 - Nd:YAG laser for posterior capsulotomy and peripheral iridotomy.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Nd:YAG laser for posterior capsulotomy and...:YAG laser for posterior capsulotomy and peripheral iridotomy. (a) Identification. The Nd:YAG laser for... laser intended for disruption of the posterior capsule or the iris via optical breakdown. The...

  7. 21 CFR 886.4392 - Nd:YAG laser for posterior capsulotomy and peripheral iridotomy.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Nd:YAG laser for posterior capsulotomy and...:YAG laser for posterior capsulotomy and peripheral iridotomy. (a) Identification. The Nd:YAG laser for... laser intended for disruption of the posterior capsule or the iris via optical breakdown. The...

  8. 21 CFR 886.4392 - Nd:YAG laser for posterior capsulotomy and peripheral iridotomy.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Nd:YAG laser for posterior capsulotomy and...:YAG laser for posterior capsulotomy and peripheral iridotomy. (a) Identification. The Nd:YAG laser for... laser intended for disruption of the posterior capsule or the iris via optical breakdown. The...

  9. Bipolar Posterior Deltoid Transfer for Massive Rotator Cuff Tears: A Report on 2 Patients

    PubMed Central

    2015-01-01

    Summary: A transfer of the posterior deltoid innervated by the posterior branch of the axillary nerve and vascularized by the posterior circumflex humeral artery is described for irreparable tears of the supra- and infraspinatus muscle tendons. Functionally useful abduction and flexion were restored in 2 patients. PMID:26090280

  10. 21 CFR 886.4392 - Nd:YAG laser for posterior capsulotomy and peripheral iridotomy.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Nd:YAG laser for posterior capsulotomy and...:YAG laser for posterior capsulotomy and peripheral iridotomy. (a) Identification. The Nd:YAG laser for... laser intended for disruption of the posterior capsule or the iris via optical breakdown. The...

  11. 21 CFR 886.4392 - Nd:YAG laser for posterior capsulotomy and peripheral iridotomy.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Nd:YAG laser for posterior capsulotomy and...:YAG laser for posterior capsulotomy and peripheral iridotomy. (a) Identification. The Nd:YAG laser for... laser intended for disruption of the posterior capsule or the iris via optical breakdown. The...

  12. Quantum probability assignment limited by relativistic causality

    PubMed Central

    Han, Yeong Deok; Choi, Taeseung

    2016-01-01

    Quantum theory has nonlocal correlations, which bothered Einstein, but found to satisfy relativistic causality. Correlation for a shared quantum state manifests itself, in the standard quantum framework, by joint probability distributions that can be obtained by applying state reduction and probability assignment that is called Born rule. Quantum correlations, which show nonlocality when the shared state has an entanglement, can be changed if we apply different probability assignment rule. As a result, the amount of nonlocality in quantum correlation will be changed. The issue is whether the change of the rule of quantum probability assignment breaks relativistic causality. We have shown that Born rule on quantum measurement is derived by requiring relativistic causality condition. This shows how the relativistic causality limits the upper bound of quantum nonlocality through quantum probability assignment. PMID:26971717

  13. Quantum probability assignment limited by relativistic causality.

    PubMed

    Han, Yeong Deok; Choi, Taeseung

    2016-01-01

    Quantum theory has nonlocal correlations, which bothered Einstein, but found to satisfy relativistic causality. Correlation for a shared quantum state manifests itself, in the standard quantum framework, by joint probability distributions that can be obtained by applying state reduction and probability assignment that is called Born rule. Quantum correlations, which show nonlocality when the shared state has an entanglement, can be changed if we apply different probability assignment rule. As a result, the amount of nonlocality in quantum correlation will be changed. The issue is whether the change of the rule of quantum probability assignment breaks relativistic causality. We have shown that Born rule on quantum measurement is derived by requiring relativistic causality condition. This shows how the relativistic causality limits the upper bound of quantum nonlocality through quantum probability assignment. PMID:26971717

  14. Assessment of the probability of contaminating Mars

    NASA Technical Reports Server (NTRS)

    Judd, B. R.; North, D. W.; Pezier, J. P.

    1974-01-01

    New methodology is proposed to assess the probability that the planet Mars will by biologically contaminated by terrestrial microorganisms aboard a spacecraft. Present NASA methods are based on the Sagan-Coleman formula, which states that the probability of contamination is the product of the expected microbial release and a probability of growth. The proposed new methodology extends the Sagan-Coleman approach to permit utilization of detailed information on microbial characteristics, the lethality of release and transport mechanisms, and of other information about the Martian environment. Three different types of microbial release are distinguished in the model for assessing the probability of contamination. The number of viable microbes released by each mechanism depends on the bio-burden in various locations on the spacecraft and on whether the spacecraft landing is accomplished according to plan. For each of the three release mechanisms a probability of growth is computed, using a model for transport into an environment suited to microbial growth.

  15. Morphology Parameters for Mirror Posterior Communicating Artery Aneurysm Rupture Risk Assessment

    PubMed Central

    JIANG, Hao; SHEN, Jian; WENG, Yu-Xiang; PAN, Jian-Wei; YU, Jian-Bo; WAN, Zi-Ang; ZHAN, Renya

    Recent studies have shown that posterior communicating artery (PComA) aneurysms are more likely to rupture. However, surgical intervention for PComA aneurysms may be associated with increased treatment-related morbidity rate. Therefore, it is meaningful to investigate the factors related to PComA aneurysm rupture. The purpose of this study was to identify morphological parameters that significantly correlate with PComA aneurysm rupture. We divided 14 pairs of mirror posterior communicating artery aneurysms (PComA-MANs) into ruptured and unruptured groups. Computed tomography angiography (CTA) imaging was evaluated with three-dimensional (3D) Slicer to generate models of the aneurysms and surrounding vasculature. Nine morphological parameters [size, height, width, neck width, aspect ratio (AR), bottleneck factor (BNF), height/width ratio (H/W), size ratio (SR), and bleb formation] were examined in the two groups for significance with respect to rupture. By contrast, statistically significant differences were found in ruptured and unruptured group for size, AR, BNF, SR, and bleb formation (P < 0.05). Parameters that had no significant differences between the two groups were height (P = 0.103), width (P = 0.078), neck width (P = 0.808), and H/W (P = 0.417). We conclude that MANs may be a useful model for the morphological analysis of intracranial aneurysm rupture. Larger size, higher AR, BNF, SR, and bleb formation may be related to rupture of PComA aneurysms. Larger sample studies minimizing the interference from patient-related factors and aneurysm type were expected for acquiring more accurate assessment of the relationship between these parameters and PComA aneurysm rupture. PMID:26041624

  16. Non-Parametric Collision Probability for Low-Velocity Encounters

    NASA Technical Reports Server (NTRS)

    Carpenter, J. Russell

    2007-01-01

    An implicit, but not necessarily obvious, assumption in all of the current techniques for assessing satellite collision probability is that the relative position uncertainty is perfectly correlated in time. If there is any mis-modeling of the dynamics in the propagation of the relative position error covariance matrix, time-wise de-correlation of the uncertainty will increase the probability of collision over a given time interval. The paper gives some examples that illustrate this point. This paper argues that, for the present, Monte Carlo analysis is the best available tool for handling low-velocity encounters, and suggests some techniques for addressing the issues just described. One proposal is for the use of a non-parametric technique that is widely used in actuarial and medical studies. The other suggestion is that accurate process noise models be used in the Monte Carlo trials to which the non-parametric estimate is applied. A further contribution of this paper is a description of how the time-wise decorrelation of uncertainty increases the probability of collision.

  17. Liquefaction probability curves for surficial geologic deposits

    USGS Publications Warehouse

    Holzer, Thomas L.; Noce, Thomas E.; Bennett, Michael J.

    2011-01-01

    Liquefaction probability curves that predict the probability of surface manifestations of earthquake-induced liquefaction are developed for 14 different types of surficial geologic units. The units consist of alluvial fan, beach ridge, river delta topset and foreset beds, eolian dune, point bar, flood basin, natural river and alluvial fan levees, abandoned river channel, deep-water lake, lagoonal, sandy artificial fill, and valley train deposits. Probability is conditioned on earthquake magnitude and peak ground acceleration. Curves are developed for water table depths of 1.5 and 5.0 m. Probabilities are derived from complementary cumulative frequency distributions of the liquefaction potential index (LPI) that were computed from 927 cone penetration tests. For natural deposits with a water table at 1.5 m and subjected to a M7.5 earthquake with peak ground acceleration (PGA)  =  0.25g, probabilities range from 0.5 for beach ridge, point bar, and deltaic deposits. The curves also were used to assign ranges of liquefaction probabilities to the susceptibility categories proposed previously for different geologic deposits. For the earthquake described here, probabilities for susceptibility categories have ranges of 0–0.08 for low, 0.09–0.30 for moderate, 0.31–0.62 for high, and 0.63–1.00 for very high. Retrospective predictions of liquefaction during historical earthquakes based on the curves compare favorably to observations.

  18. Robust Model-Free Multiclass Probability Estimation

    PubMed Central

    Wu, Yichao; Zhang, Hao Helen; Liu, Yufeng

    2010-01-01

    Classical statistical approaches for multiclass probability estimation are typically based on regression techniques such as multiple logistic regression, or density estimation approaches such as linear discriminant analysis (LDA) and quadratic discriminant analysis (QDA). These methods often make certain assumptions on the form of probability functions or on the underlying distributions of subclasses. In this article, we develop a model-free procedure to estimate multiclass probabilities based on large-margin classifiers. In particular, the new estimation scheme is employed by solving a series of weighted large-margin classifiers and then systematically extracting the probability information from these multiple classification rules. A main advantage of the proposed probability estimation technique is that it does not impose any strong parametric assumption on the underlying distribution and can be applied for a wide range of large-margin classification methods. A general computational algorithm is developed for class probability estimation. Furthermore, we establish asymptotic consistency of the probability estimates. Both simulated and real data examples are presented to illustrate competitive performance of the new approach and compare it with several other existing methods. PMID:21113386

  19. Seismicity alert probabilities at Parkfield, California, revisited

    USGS Publications Warehouse

    Michael, A.J.; Jones, L.M.

    1998-01-01

    For a decade, the US Geological Survey has used the Parkfield Earthquake Prediction Experiment scenario document to estimate the probability that earthquakes observed on the San Andreas fault near Parkfield will turn out to be foreshocks followed by the expected magnitude six mainshock. During this time, we have learned much about the seismogenic process at Parkfield, about the long-term probability of the Parkfield mainshock, and about the estimation of these types of probabilities. The probabilities for potential foreshocks at Parkfield are reexamined and revised in light of these advances. As part of this process, we have confirmed both the rate of foreshocks before strike-slip earthquakes in the San Andreas physiographic province and the uniform distribution of foreshocks with magnitude proposed by earlier studies. Compared to the earlier assessment, these new estimates of the long-term probability of the Parkfield mainshock are lower, our estimate of the rate of background seismicity is higher, and we find that the assumption that foreshocks at Parkfield occur in a unique way is not statistically significant at the 95% confidence level. While the exact numbers vary depending on the assumptions that are made, the new alert probabilities are lower than previously estimated. Considering the various assumptions and the statistical uncertainties in the input parameters, we also compute a plausible range for the probabilities. The range is large, partly due to the extra knowledge that exists for the Parkfield segment, making us question the usefulness of these numbers.

  20. Heterogeneous and nonlinear development of human posterior parietal cortex function.

    PubMed

    Chang, Ting-Ting; Metcalfe, Arron W S; Padmanabhan, Aarthi; Chen, Tianwen; Menon, Vinod

    2016-02-01

    Human cognitive problem solving skills undergo complex experience-dependent changes from childhood to adulthood, yet most neurodevelopmental research has focused on linear changes with age. Here we challenge this limited view, and investigate spatially heterogeneous and nonlinear neurodevelopmental profiles between childhood, adolescence, and young adulthood, focusing on three cytoarchitectonically distinct posterior parietal cortex (PPC) regions implicated in numerical problem solving: intraparietal sulcus (IPS), angular gyrus (AG), and supramarginal gyrus (SMG). Adolescents demonstrated better behavioral performance relative to children, but their performance was equivalent to that of adults. However, all three groups differed significantly in their profile of activation and connectivity across the PPC subdivisions. Activation in bilateral ventral IPS subdivision IPS-hIP1, along with adjoining anterior AG subdivision, AG-PGa, and the posterior SMG subdivision, SMG-PFm, increased linearly with age, whereas the posterior AG subdivision, AG-PGp, was equally deactivated in all three groups. In contrast, the left anterior SMG subdivision, SMG-PF, showed an inverted U-shaped profile across age groups such that adolescents exhibited greater activation than both children and young adults. Critically, greater SMG-PF activation was correlated with task performance only in adolescents. Furthermore, adolescents showed greater task-related functional connectivity of the SMG-PF with ventro-temporal, anterior temporal and prefrontal cortices, relative to both children and adults. These results suggest that nonlinear up-regulation of SMG-PF and its interconnected functional circuits facilitate adult-level performance in adolescents. Our study provides novel insights into heterogeneous age-related maturation of the PPC underlying cognitive skill acquisition, and further demonstrates how anatomically precise analysis of both linear and nonlinear neurofunctional changes with age is necessary for more fully characterizing cognitive development. PMID:26655682

  1. Posterior dynamic stabilization: The interspinous spacer from treatment to prevention

    PubMed Central

    Nachanakian, Antoine; El Helou, Antonios; Alaywan, Moussa

    2016-01-01

    Introduction: Managements of lumbar stenosis evoluted over the time from decompression to dynamic stabilization preserving the motion segment passing by the rigid fixation. After long years of rigid fusion, adjacent segment disease became more and more frequent and the concept of dynamic stabilization emerged. Materials and Methods: We report our experience with posterior dynamic stabilization using an interspinous distracter (ISD). One hundred and eight patients were operated between September 2008 and January 2012 with different lumbar spine pathologies. The ages of our patients were between 45 years and 70 years, with a mean age of 55 years. With our growing experience, indication of ISD became narrowed and the interspinous spacer became an absolute tool for adjacent segment disease as a treatment as well as prophylactic with rigid stabilization. Results and Discussion: Overall clinical improvement was noted in ISD-treated patients, with considerable satisfaction in 77% of patients on average. The patient at first reported an improvement of their radicular pain with a mean reduction of 3.6/10 on visual analog scale. Post-operative walking distance progressively increased during the next 3 months. Whereas, a radiological evaluation at 3 months showed a mean of 42% improvement of the disc height. On the other hand, all patients operated with posterior dynamic stabilization (PDS) at the time of rigid stabilization showed no adjacent segment disease compared to those operated with posterior arthrodesis (P < 0.05). Conclusion: Interspinous spacer after surgical decompression for spinal stenosis by excision of Ligamentum flavum demonstrates excellent short-term and long-term results for improvement in back pain, neurogenic claudication, and patient satisfaction. It provides restoration of disc height, reduction of vertebral slip and it's a necessary tool in the management and the prevention of adjacent segment disease. PMID:27057211

  2. Minimal incision posterior approach levator plication for aponeurotic ptosis

    PubMed Central

    Ng, D S; Chan, E; Ko, S T

    2015-01-01

    Purpose To assess the efficacy and predictability of a minimal incision posterior approach levator plication technique for correction of involutional ptosis. Method Retrospective chart review of patients with involutional aponeurotic ptosis underwent minimal incision posterior approach levator plication technique between August 2013 and June 2014 by a single surgeon. The upper lid was double everted, and the conjunctiva and Muller's muscle layers were incised vertically until the levator aponeurosis could be identified. The incision(s) was similar to performing incision and curettage of chalazion, except that the site was above the tarsal plate and extended towards the fornix. Then insertion of aponeurosis was dissected away from the anterior tarsal surface, and the more superiorly located levator was plicated on it with double arm suture(s). No tissue was excised in this procedure. Surgical success was defined as a postoperative margin reflex distance (MRD)>2 mm and<4.5 mm, interlid height<1 mm and satisfactory contour. Results Forty-four lids of 27 patients were included. Preoperative mean MRD was 0.48 +/− 0.56 mm. Severe ptosis of MRD<1 mm was present in 34/44 patients (77.3%). The postoperative mean MRD was 2.49 +/− 0.53 mm, and mean improvement was 2.02 +/− 0.61 mm, which was statistically significant (P<0.001). The overall success rate was 38/44 (86.4%). Conclusions Minimal incision posterior approach to levator plication was effective for the correction of aponeurotic ptosis with moderate to good levator function. PMID:25613849

  3. Minimally invasive tubular access for posterior cervical foraminotomy

    PubMed Central

    Branch, Byron C.; Hilton, Donald L.; Watts, Clark

    2015-01-01

    Background: Minimally invasive tubular access for posterior cervical foraminotomy can be an effective and safe technique for decompression of the nerve root utilizing minimally invasive muscle splitting with routine outpatient discharge. This technique has come under scrutiny calling into question the associated learning curve, a subjective limited exposure provided, and an argument that the risks and complications are largely unknown. In response to previously published critiques, this study aims to describe the outcomes and complications associated with this technique in a large patient series. Methods: A retrospective chart review was performed from 1999 to 2013 capturing a single surgeon's experience with the minimally invasive tubular access for posterior cervical foraminotomy technique from a single institution, encompassing 463 patients. Surgical outcome documented at follow-up and complications were obtained from this patient series. Additional variables analyzed include: Hospital length of stay, number of levels operated, targeted root for decompression, side operated, length of surgery, and estimated blood loss. Results: Outpatient discharge was achieved in 91.6% of cases. There were 10 complications (2.2%) among the 463 patients undergoing this technique from 1999 to 2013. Patients were followed for an average of 1 year and 2 months postoperatively. Improvement from the preoperative condition was observed in 98.2% of patients and excellent outcomes with patients reporting complete relief of symptoms with no or mild residual discomfort was seen in 92.2%. Conclusions: Compared with open techniques, minimally invasive tubular access for posterior cervical foraminotomy demonstrates comparable, if not superior, complication rates, and patient outcomes. PMID:26009705

  4. Prolapse of the posterior leaflet: resect or respect

    PubMed Central

    Hohenberger, Wolfgang; Lakew, Fitsum; Diegeler, Anno

    2015-01-01

    Prolapse of the posterior leaflet (PPL) is the most frequent dysfunction of the mitral valve in the western world. Quadrangular resection, first proposed by Alain Carpentier, has progressed to become the gold standard modality to repair posterior leaflet prolapse. Although this “resection technique” is safe, reproducible, and offers favorable long term results, it presents major drawbacks. Firstly, it leads to a reduced surface of coaptation, the ultimate goal of mitral valve repair; secondly, it does not respect the anatomy of the mitral valve; thirdly, it leads to a deformation of the base of the ventricle; and finally, degenerative disease of the mitral valve is a spectrum of lesions depending on the amount of excess tissue, and hence, a one technique-fits-all strategy cannot meet the absolute necessity to repair all mitral valve patients with PPL. Therefore, new approaches which have been proposed place greater emphasis on respecting, rather than only resecting, the leaflet tissue in order to avoid the drawbacks of the “resection” approach. The use of artificial chordae to correct the leaflet prolapse restores the normal anatomy and physiology of the mitral valve, thus producing an optimal surface of coaptation. However, this approach is limited by anatomical variances. As a community, we should expand our vision and define a clear and helpful strategy for PPL: to obtain a high, smooth and regular surface of coaptation located in the inflow of the left ventricle. To achieve this goal, it is necessary to have a high level of respect for the leaflet tissue in order to obtain the best surface of coaptation. Nonetheless, a limited resection may be needed to remodel the posterior leaflet, so that it will be smooth and regular. PMID:26309830

  5. The 90-degree rule in posterior ptosis surgery.

    PubMed

    Sobti, Deepak; Patel, Ankit B; Mancini, Ronald

    2016-04-01

    To propose a guideline for ptosis clamp positioning to minimize the risk of globe injury during posterior ptosis surgery. Measurements of 20 consecutive patients, 40 eyelids, undergoing bilateral posterior ptosis repair surgery were taken; as a surrogate for needle tip position, measurement of the distance from the clamp base to the ocular surface was taken using a caliper with the clamp held at 90-degrees to the ocular surface and again at 45-degrees to the ocular surface. These measurements were compared to geometric predictions of the distance from the clamp base to the ocular surface. The average distance from the clamp base to the ocular surface when the clamp is held 90-degrees to the ocular surface was 7 mm, this distance decreases to 5 mm when the clamp is held 45° to the ocular surface. This coincides well with geometric predictions. Posterior ptosis surgery overall has an excellent safety profile; however, complications are possible, perhaps the most severe of which is inadvertent globe and/or corneal injury. The more acute the angle the ptosis clamp is held, the closer the clamp base, and subsequently the needle tip, is to the ocular surface as would be predicted geometrically. This coincides with closer proximity of the needle to the ocular surface during surgery. The theoretical risk of globe injury should decrease as the distance of the needle from the globe increases, and this distance is greatest when the clamp is held at a 90-degree angle to the ocular surface. This distinction becomes particularly important to consider in large eye morphology patients where the distance from the needle to the globe can approach 2 mm when the clamp is held at 45-degrees. PMID:26253459

  6. Relative Transition Probabilities of Rare Gases

    NASA Astrophysics Data System (ADS)

    Delanis, Daniel; Duncan-Chamberlin, Katherine; Piracha, Naveed

    2011-04-01

    We have measured relative transition probabilities for emissions from the noble gasses using hollow cathode lamps. Relative transition probabilities are reported for thirty lines from Ne I, twenty-four lines from Ar I, fourteen lines from Kr I, and twenty-one lines from Xe I. All transitions discussed are from the 2p level to 1s levels. Uncertainty has been measured and found to be within 5%. This data can be applied to calibrate the relative detection efficiency of a spectrometer over a range of 4000 å--10000 å. Comparisons between the relative transition probabilities of each species is discussed.

  7. A Massive Posterior Neck Mass: Lipoma or Something More Sinister?

    PubMed Central

    Ryan, Matthew F.

    2013-01-01

    Lipomas are slow-growing benign soft-tissue tumors which are typically asymptomatic and occur in approximately 1% of the population. A lipoma is considered to be of excessive size when it is greater than 10 cm in length (in any dimension) or weighs over 1000 g (Kransdorf (1995)). We describe a case of a man presenting with a giant posterior neck mass which greatly reduced the sagittal range of cervical spine. A discussion of the pathophysiology of lipomas and a literature review regarding giant lipomas versus malignancy follows. PMID:24223314

  8. Hereditary anterior megalophthalmos with posterior vitreoretinopathy: a surgical challenge

    PubMed Central

    Rao, Aparna; Videkar, Chetan

    2014-01-01

    Anterior megalophthalmos is an inherited condition characterised by enlargement of the anterior segment with associated glaucoma and vitreoretinopathy. These associations make surgical management very challenging. A 12-year-old boy, diagnosed and operated elsewhere for congenital glaucoma in both eyes, presented with raised intraocular pressure. Investigations revealed enlarged corneal diameter, increased anterior chamber depth with thick, clear cornea and no Haab striae while fundus evaluation revealed posteriorly dislocated cataractous lens with total rhegmatogenous retinal detachment in both eyes. The surgical challenges in management are highlighted in this case where appropriate investigations can aid in the selection of appropriate surgeries with good visual outcome. PMID:24632899

  9. Simple posterior frequency correction for vibrational spectra from molecular dynamics

    NASA Astrophysics Data System (ADS)

    Tikhonov, Denis S.

    2016-05-01

    Vibrational spectra computed from molecular dynamics simulations with large integration time steps suffer from nonphysical frequency shifts of signals [M. Praprotnik and D. Janežič, J. Chem. Phys. 122, 174103 (2005)]. A simple posterior correction technique was developed for compensation of this behavior. It performs through replacement of abscissa in the calculated spectra using following formula: ν corrected = /√{ 2 ṡ (" separators=" 1 - cos ( 2 π ṡ Δ t ṡ ν initial ) ) } 2 π ṡ Δ t , where ν are initial and corrected frequencies and Δt is the MD simulation time step. Applicability of this method was tested on gaseous infrared spectra of hydrogen fluoride and formic acid.

  10. Consolidation of Complex Events via Reinstatement in Posterior Cingulate Cortex

    PubMed Central

    Keidel, James L.; Ing, Leslie P.; Horner, Aidan J.

    2015-01-01

    It is well-established that active rehearsal increases the efficacy of memory consolidation. It is also known that complex events are interpreted with reference to prior knowledge. However, comparatively little attention has been given to the neural underpinnings of these effects. In healthy adults humans, we investigated the impact of effortful, active rehearsal on memory for events by showing people several short video clips and then asking them to recall these clips, either aloud (Experiment 1) or silently while in an MRI scanner (Experiment 2). In both experiments, actively rehearsed clips were remembered in far greater detail than unrehearsed clips when tested a week later. In Experiment 1, highly similar descriptions of events were produced across retrieval trials, suggesting a degree of semanticization of the memories had taken place. In Experiment 2, spatial patterns of BOLD signal in medial temporal and posterior midline regions were correlated when encoding and rehearsing the same video. Moreover, the strength of this correlation in the posterior cingulate predicted the amount of information subsequently recalled. This is likely to reflect a strengthening of the representation of the video's content. We argue that these representations combine both new episodic information and stored semantic knowledge (or “schemas”). We therefore suggest that posterior midline structures aid consolidation by reinstating and strengthening the associations between episodic details and more generic schematic information. This leads to the creation of coherent memory representations of lifelike, complex events that are resistant to forgetting, but somewhat inflexible and semantic-like in nature. SIGNIFICANCE STATEMENT Memories are strengthened via consolidation. We investigated memory for lifelike events using video clips and showed that rehearsing their content dramatically boosts memory consolidation. Using MRI scanning, we measured patterns of brain activity while watching the videos and showed that, in a network of brain regions, similar patterns of brain activity are reinstated when rehearsing the same videos. Within the posterior cingulate, the strength of reinstatement predicted how well the videos were remembered a week later. The findings extend our knowledge of the brain regions important for creating long-lasting memories for complex, lifelike events. PMID:26511235

  11. [A painful occipital mass revealing a posterior encephalocele].

    PubMed

    Meunier, Sarah; Michalak, Sophie; Chaigneau, Julien; Mercier, Philippe; Rousseau, Audrey

    2014-08-01

    Encephalocele is a congenital malformation caused by a neural tube defect during embryonic development. We report a case of posterior encephalocele in a 7-month-old infant with a painful occipital mass known since birth. Pathological examination of the mass showed different mature tissues derived from the brain and its coverings (e.g., neuroglia, ependymal canals and clusters of meningothelial cells). A diagnosis of encephalocele was made. The different forms of neural tube defect will be briefly discussed, especially the "aborted" forms (e.g., non-specific midline mass lesion or angioma) that the pathologist may encounter in his/her daily practice. PMID:25132445

  12. Endophthalmitis following Nd:YAG laser posterior capsulotomy.

    PubMed

    Carlson, A N; Koch, D D

    1988-03-01

    We report the development of Propionibacterium acnes endophthalmitis following Nd:YAG laser posterior capsulotomy. The patient previously underwent uncomplicated extracapsular cataract extraction with intraocular lens insertion and was free of inflammation prior to laser capsulotomy. Diagnostic vitrectomy and aqueous tap were performed, and P. acnes was isolated from the aqueous in thiol broth media after nine days of incubation under anaerobic conditions. The patient was managed with topical and systemic antibiotics and steroids. Complete resolution of inflammation with return of vision to 20/25 was achieved without removal of the intraocular lens or lenticular remnants. PMID:3258419

  13. Neuralgic Amyotrophy Manifesting as Mimicking Posterior Interosseous Nerve Palsy

    PubMed Central

    Yang, Jin Seo; Kang, Suk Hyung; Choi, Eun Hi

    2015-01-01

    The upper trunk of the brachial plexus is the most common area affected by neuralgic amyotrophy (NA), and paresis of the shoulder girdle muscle is the most prevalent manifestation. Posterior interosseous nerve palsy is a rare presentation in patients with NA. It results in dropped finger on the affected side and may be misdiagnosed as entrapment syndrome or compressive neuropathy. We report an unusual case of NA manifested as PIN palsy and suggest that knowledge of clinical NA phenotypes is crucial for early diagnosis of peripheral nerve palsies. PMID:26713154

  14. Foraminotomia cervical posterior en el tratamiento de conflictos foraminales

    PubMed Central

    Campero, Álvaro; Barrera, Ramiro; Ajler, Pablo

    2012-01-01

    Introducción: La foraminomotima cervical posterior es un procedimiento utilizado para la descompresion radicular por via posterior y constituye una alternativa a la via clásica anterior. En este trabajo evaluamos nuestra serie de pacientes tratados por esta via. Método: Desde enero de 2008 a diciembre de 2011, 17 pacientes (18 foraminotomías) fueron operados por presentar cervicobraquialgia a causa de un conflicto foraminal, realizando un foraminotomía cervical posterior. Los pacientes fueron evaluados en el postoperatorio inmediato, al mes y a los 3 meses de la cirugía. Los parámetros para valorar los resultados fueron la Escala Análoga del Dolor (VAS), la Neck Disability Index y los criterios de Odom. Resultados: El dolor radicular por conflicto foraminal secundario a hernia de disco cervical fue el síntoma y la patología predominante. El nivel más afectado fue C5-C6. La resolución completa del dolor radicular se observó en casi todos los pacientes. La VAS preoperatoria en promedio fue de 8.8 (mínimo 8 – máximo 10), con una franca mejoría en todos los casos (0.4 en el último control). La media en la Neck Disability Index al inicio fue de 35.3 (mínimo 32 – máximo 45), con una evolución favorable en la evaluación final (0.6). Los Criterios de Odom para la evaluación de pacientes operados de columna cervical fueron satisfactorios con un promedio de 1.17. Se observaron complicaciones en 4 pacientes (23%), todas tuvieron una evolución favorable. No hubo infecciones, discitis ni empeoramiento de los síntomas preexistentes en ningún paciente. Conclusión: La foraminotomía cervical posterior es un procedimiento efectivo para el tratamiento del dolor radicular en los conflictos foraminales PMID:23596556

  15. Posterior dislocation of the sternoclavicular joint leading to mediastinal compression.

    PubMed

    Jougon, J B; Lepront, D J; Dromer, C E

    1996-02-01

    Dislocations of the sternoclavicular joint are uncommon, and the posterior variety have a potential for considerable morbidity. We report a case with compression of the vital structures within the superior mediastinum. It was a rugby player getting run over by the scrum. The mechanism was an indirect force exerted forward and laterally against the shoulder. The patient complained of pain and dysphagia. A systolic right cervical murmur was heard. Angiography was normal and esophagography showed extrinsic esophageal compression. Surgical reduction was performed because there was a slight pneumomediastinum on the computed tomography. This case report demonstrates the mechanism, complications, and treatment of such a lesion. PMID:8572795

  16. Seizure induced polytrauma; not just posterior dislocation of the shoulder.

    PubMed

    Gill, James Ritchie; Murphy, Colin G; Quansah, Benjamin; Carrothers, Andrew D

    2015-01-01

    A 61-year-old woman sustained multiple fractures secondary to the tonic clonic muscular contractions of a seizure. Her injuries included: bilateral proximal humerus posterior fracture dislocations, manubrium fracture, unstable sixth thoracic vertebrae crush fracture, bilateral acetabular fractures and a left femoral neck fracture. Seizures are a rare but recognised cause of fracture. Patients with osteoporosis are more susceptible to more serious fractures to long bones, spine and pelvis. The lack of history of high-energy trauma can lead to a delay in diagnosis. Rarely, the combination and magnitude of these injuries can be life-threatening. PMID:26307650

  17. Application of sonography for evaluation of posterior circulation disorders.

    PubMed

    Alpaidze, M; Janelidze, M

    2014-03-01

    Posterior circulation disorders (PCD) include a) vertebrobasilar insufficiency (VBI), which has a wide clinical manifestation such as vestibulocerebellar syndrome, cephalalgia, cochlear syndrome, vegetovascular dystonia, visual disturbances, "syndrome of vertebral artery compression" etc, b) vertebrobasilar TIA and c) stroke. All of them are caused by blood flow disturbances in vertebral (VA), basilar (BAS) and posterior cerebral arteries (PCA). Aim - evaluation of role of extracranial duplex-sonography (EDS), transcranial color-coded duplex-sonography (TCCD) and rotational functional tests (RFT) in PCD. 88 patients (age range 18-62y) with PCD and 20 healthy controls with relevant age range were examined using EDS, TCCD and RFT with measurement of vertebral arteries (VA) diameter, mean flow velocities (MFV) and pulsatility index (PI) in VA, basilar artery (BAS) and posterior cerebral arteries (PCA). For statistical analysis SPSS software (Version 11.5) was used. In 48 (54,5%) patients revealed unilateral narrowing (less than 2.5 mm in diameter) and deformation of vertebral artery associated with osteochondrosis or primary hypoplasia. In 11 (12,5%) patients revealed bilateral narrowing (less than 2.8 mm in diameter) and deformation of vertebral arteries. Ultrasound investigation showed a decrease of MFV (23 ± 1.4 cm/sec) in the intracranial length of vertebral artery and an increase of PI (3,2 ±0,3 p=0,002) in the extracranial segments (V1- V3). In 52 cases (59%) revealed decrease of MFV in BAS by 32.6 ± 4.7% and in 41 cases (46.5%) decrease of MFV in both PCA by 24.8 ± 5.2% (P<0.002). In 21 cases (23.8%) revealed concurrent development of vertebrogenic reflex vasoconstriction. In 18 patients (20.4%) exposed only deformation of vertebral arteries with local increase of MFV and normal values in intracranial segments. Rotational tests were positive in 42 (47.7%) patients and manifested high correlation with clinical data. EDS and TCCD are important tools for estimation of high hemodynamic risk in patients with PCD. Rotation induced vertebrobasilar ischemia with temporary impairment of cerebral blood flow to the brainstem, thalamus, and occipital lobes predicts possible posterior circulation TIA or stroke and helps with proper selection of further treatment strategy. PMID:24743118

  18. Amoebic cervicitis mimicking posterior wall fibroid: a rare presentation.

    PubMed

    Mukherjee, Soma; Nagarsenkar, Ajit; Chandra, Savita; Sahasrabhojanee, Mrinalini; Sawant, Dheeraj

    2014-08-01

    Amoebiasis of the uterine cervix is an extremely rare entity, and presentation as fibroid uterus has not been reported, to the best of our knowledge in our extensive search of the English literature. It can clinically simulate cervical malignancy by virtue of surface papillomatous and overall ulcerated and necrotic appearance. We present a case of amoebic infection of the cervix in a 45-year-old female which was suspected to be a posterior wall fibroid with degeneration until a histopathological examination of the surgical specimen revealed the presence of Entamoeba histolytica trophozoites. The patient recovered after surgery and antiamoebic therapy. PMID:22743593

  19. Practical application of composite resin techniques in the posterior dentition.

    PubMed

    Chandrapal, A

    2016-03-11

    Posterior direct resin restorations are the combination of appreciation of anatomy, form and art. We require an understanding of the ideal form and metrics to control occlusal forces whilst layering our composite resin in the most amenable fashion to enable a predictable and asymptomatic restoration which looks and functions much like that of the natural dentition. In this article, and his associated presentation at the British Dental Conference and Exhibition 2016, Dr Chandrapal will discuss the methodology and practical based tips required to form clinical success within the environment of limited time, thus avoiding unnecessary complexities. PMID:26964605

  20. Echocardiographic Manifestation of Esophagitis Mimicking a Posterior Mediastinal Mass

    PubMed Central

    Swarup, Supreeya; Kantamneni, Sowmya; Kabir, Sarah; Zeltser, Roman; Makaryus, Amgad N

    2014-01-01

    Incidental extracardiac findings (ECFs) are commonly noted on cardiac imaging. The majority of the ECFs are noticed on computed tomography (CT), cardiac magnetic resonance scanning, and myocardial perfusion imaging. Although transthoracic echocardiography (TTE) is a widely used cardiac modality, there is scarcity of data describing ECF on TTE. ECFs have the potential to alter patient management. We present a rare case of a cystic mass seen in the posterior mediastinum on TTE, which led to further evaluation and diagnosis of esophagitis with ulceration. PMID:25780343

  1. Reconstructive Options for Oncologic Posterior Trunk Defects: A Review

    PubMed Central

    Behr, Björn; Wagner, Johannes M.; Wallner, Christoph; Harati, Kamran; Lehnhardt, Marcus; Daigeler, Adrien

    2016-01-01

    After oncological tumor resections at the back, large defects can remain that depending on the size and location may represent reconstructive challenges to plastic surgeons. Flap selection includes the entire armamentarium of coverage, including transposition flaps, perforator flaps, pedicled muscle flaps, and free flaps. Most defects can be closed and reconstructed with local or pedicled muscle flaps. In our hands, sufficient closure could be obtained with all techniques, except the latissimus dorsi turn-over flap. Thereupon, an algorithm for closure of posterior trunk defects related to the anatomical region is proposed. PMID:27014626

  2. Considerations for ceramic inlays in posterior teeth: a review

    PubMed Central

    Hopp, Christa D; Land, Martin F

    2013-01-01

    This review of ceramic inlays in posterior teeth includes a review of the history of ceramic restorations, followed by common indications and contraindications for their use. A discussion on the potential for tooth wear is followed by a review of recommended preparation design considerations, fabrication methods, and material choices. Despite the improved materials available for fabrication of porcelain inlays, fracture remains a primary mode of inlay failure. Therefore, a brief discussion on strengthening methods for ceramics is included. The review concludes with a section on luting considerations, and offers the clinician specific recommendations for luting procedures. In conclusion, inlay success rates and longevity, as reported in the literature, are summarized. PMID:23750101

  3. Using a new condensable composite for posterior restorations.

    PubMed

    Poss, S D

    1999-01-01

    This article discusses the properties of condensable composites and how their filler particles are continually being improved to create an updated, advanced tooth-colored material that can be packed with the same clinical success as amalgam in posterior restorations. Many dental companies are now addressing the major concerns of shrinkage, polishability, and discoloration that inundated previous composites by introducing the next generation of condensable composites. With increased filler content and the addition of special additives to the resin phase, Prodigy Condensable allows clinicians to follow the same protocol for placing amalgam restorations while being assured of improved wear-resistance, strength, longevity, postoperative sensitivity, and esthetics. PMID:12089754

  4. Complications of Anterior and Posterior Cervical Spine Surgery

    PubMed Central

    Cheung, Jason Pui Yin

    2016-01-01

    Cervical spine surgery performed for the correct indications yields good results. However, surgeons need to be mindful of the many possible pitfalls. Complications may occur starting from the anaesthestic procedure and patient positioning to dura exposure and instrumentation. This review examines specific complications related to anterior and posterior cervical spine surgery, discusses their causes and considers methods to prevent or treat them. In general, avoiding complications is best achieved with meticulous preoperative analysis of the pathology, good patient selection for a specific procedure and careful execution of the surgery. Cervical spine surgery is usually effective in treating most pathologies and only a reasonable complication rate exists. PMID:27114784

  5. Choroidal vasculitis in acute posterior multifocal placoid pigment epitheliopathy.

    PubMed Central

    Spaide, R. F.; Yannuzzi, L. A.; Slakter, J.

    1991-01-01

    A 24-year-old Caucasian female presented with acute posterior multifocal placoid pigment epitheliopathy (APMPPE) and associated infiltration round some of the larger choroidal blood vessels. This infiltration dissipated as the patient's clinical condition improved and did not induce any permanent alteration of the overlying retinal pigment epithelium. We suggest that the infiltration round the choroidal vessels was due to a choroidal vasculitis. The finding of choroidal inflammation in this case lends support to the hypothesis that choroidal vasculitis is an underlying pathological process in APMPPE. Images PMID:1793461

  6. Osteochondroma of Maxilla Posterior Region: A Unique Case

    PubMed Central

    Singhal, Sachin; Goyal, Megha; Sharma, Bhuvnesh

    2015-01-01

    Osteochondroma is the most common benign neoplasm of the skeleton commonly affecting the long bones due to endochondral growth. In the craniofacial region this tumour is very rare. The sites of predilection are the coronoid process and the mandibular condyle. Here, we report an exceptional case of osteochondroma originating from the maxillary posterior region in a 26-year-old male patient, mimicking an odontome, not reported earlier in the literature. We also discuss the importance of various imaging modalities, most importantly, computed tomography (CT) in the evaluation of such lesions. However, histopathology remains the mainstay for definitive diagnosis in such conditions. PMID:26023654

  7. Isolated posterior malleolus fracture: a rare injury mechanism

    PubMed Central

    Serbest, Sancar; Tiftikçi, Uğur; Tosun, Haci Bayram; Kesgin, Engin; Karataş, Metin

    2015-01-01

    Sprain of the ankle is undoubtedly a common injury during athletic activity, and the sprain can be also associated with fracture of the ankle. Isolated posterior malleolus fracture is a very rare condition, which is usually missed. Here, we are presenting a 37 years old female patient, who suffered injury secondary pressing on brake pedal during collision in a traffic accident. Clinical evaluation is based on Ottawa Ankle Rules and a fracture is diagnosed; patient is started on daily activities at postoperative Week 8. This study aims to emphasize that Ottawa Ankle Rules are usually efficient for evaluating fractures of ankle, but clinicians should always make a detailed physical examination. PMID:26097627

  8. Current approach in the diagnosis and management of posterior uveitis

    PubMed Central

    Sudharshan, S; Ganesh, Sudha K; Biswas, Jyotrimay

    2010-01-01

    Posterior uveitic entities are varied entities that are infective or non-infective in etiology. They can affect the adjacent structures such as the retina, vitreous, optic nerve head and retinal blood vessels. Thorough clinical evaluation gives a clue to the diagnosis while ancillary investigations and laboratory tests assist in confirming the diagnosis. Newer evolving techniques in the investigations and management have increased the diagnostic yield. In case of diagnostic dilemma, intraocular fluid evaluation for polymerase chain testing for the genome and antibody testing against the causative agent provide greater diagnostic ability. PMID:20029144

  9. Intractable Hiccups Due to Posterior Inferior Cerebellar Artery Aneurysm

    PubMed Central

    Chehab, Monzer; Noujaim, Samir; Qahwash, Omar; Mezwa, Duane; Roy, Anindya

    2015-01-01

    This is the third reported case of a posterior inferior cerebellar artery (PICA) aneurysm presenting as intractable hiccups (IH). A previously healthy 29-year-old woman was admitted with a 2-week history of hiccups occurring >100 times per minute. Symptoms persisted despite numerous noninvasive therapies. Magnetic resonance imaging and magnetic resonance angiogram of the brain showed a left PICA aneurysm that was confirmed by catheter angiography. Symptoms resolved following suboccipital craniotomy and resection. Although rare, PICA aneurysm is a potentially curable cause of IH. PMID:26251787

  10. The efficacy and complications of posterior hemivertebra resection.

    PubMed

    Zhang, Jianguo; Shengru, Wang; Qiu, Guixing; Yu, Bin; Yipeng, Wang; Luk, Keith D K

    2011-10-01

    There have been several reports on hemivertebra resection via a posterior-only procedure. However, the number of reported cases is small, and various types of instrumentation have been used. In our study, we retrospectively investigated 56 consecutive cases of congenital scoliosis that were treated by posterior hemivertebra resection with transpedicular instrumentation. Radiographs were reviewed to determine the type and location of the hemivertebra, the coronal curve magnitude and the sagittal alignment pre-operatively, post-operatively and at the latest follow-up. Radiographs were also used to assess implant failure and inter-body fusion. Surgical reports and patient charts were reviewed to record any peri-operative complications. Fifty-eight posterior hemivertebrae resections from 56 patients aged 1.5-17 years with fully segmented non-incarcerated hemivertebra were evaluated. The average age at surgery was 9.9 years (1.5-17 years). The average follow-up was 32.9 months (24-58 months). The mean fusion level was 5.0 segments (2-11 segments). There was a mean improvement of 72.9% in the segmental scoliosis, from 42.4° before surgery to 12.3° at the time of the latest follow-up, and there was a mean improvement of 70% in segmental kyphosis from 42.0° to 14.5° over the same time period. The thoracic kyphosis (T5-T12) averaged 10.8° before surgery and 23.9° at the latest follow-up. The lumbar lordosis (L1-S1) averaged -52.8° before surgery and -51.6° at the latest follow-up. Two cases with neurological claudications had complete recovery immediately after the surgery. There was one case of delayed wound healing, two fractures of the pedicle at the instrumented level, two rod breakages and one proximal junction kyphosis that required revision. There were no neurological complications. Radiolucent gaps were found in the residual space after resection on the lateral view in five cases, without any sign of implant failure or correction loss. Our results show that one-stage posterior hemivertebra resection with transpedicular instrumentation can achieve excellent correction, 360° decompression and short fusion without neurological complications. Pedicle cutting still remains a challenge in younger children when using bisegmental instrumentation. In addition, the radiolucent gaps in the residual space require further investigation. PMID:21318279

  11. Patterns of attachment of the myodural bridge by the rectus capitis posterior minor muscle.

    PubMed

    Yuan, Xiao-Ying; Yu, Sheng-Bo; Li, Yun-Fei; Chi, Yan-Yan; Zheng, Nan; Gao, Hai-Bin; Luan, Bing-Yi; Zhang, Zhao-Xi; Sui, Hong-Jin

    2016-03-01

    The myodural bridge was first described by Hack in 1995 and was thought to be related to chronic cervicogenic headaches. For a long time, few studies revealed the patterns of the myodural bridge considering the rectus capitis posterior minor muscle. In this study, P45 plastination technology and anatomical dissection were performed on head specimens, and four different terminal region types of the rectus capitis posterior minor muscle were observed, including the posterior atlanto-occipital interspace, posterior arch of the atlas and posterior atlanto-axial interspace. We propose that the myodural complex structures in the posterior atlanto-occipital and posterior atlanto-axial interspace have cooperative effects on cerebrospinal fluid and work together. This force might be an important source for the circulation of cerebrospinal fluid. PMID:25859757

  12. Recent progress in the diagnosis and treatment of posterior tibial plateau fractures

    PubMed Central

    Chen, Hongwei; Chang, Shimin; Pan, Jun

    2015-01-01

    The posterior tibial plateau fracture is drawing increasing attention from orthopedists in recent years with the popularity of CT. However, due to the particular and severity of posterior tibial plateau fracture, there is still controversy in its classification and treatment. It is very difficult to achieve the ideal reduction and fixation by conventional techniques and approaches. The modified posterior approach is favorable for posterior tibial plateau fracture, but disadvantages remain. Recently, the lateral approach is applied by doctors. It is ideal for treatment of posterior tibial plateau fracture. Because of the complexity of local anatomical structure, the operative management of posterior tibial plateau fractures is a contentious issue as revealed in the recent surge of published literature addressing the surgical approach. This review mainly summaries the diagnosis, classification and surgery of the posterior tibial plateau fractures. PMID:26131147

  13. On Convergent Probability of a Random Walk

    ERIC Educational Resources Information Center

    Lee, Y.-F.; Ching, W.-K.

    2006-01-01

    This note introduces an interesting random walk on a straight path with cards of random numbers. The method of recurrent relations is used to obtain the convergent probability of the random walk with different initial positions.

  14. Stimulus probability effects in absolute identification.

    PubMed

    Kent, Christopher; Lamberts, Koen

    2016-05-01

    This study investigated the effect of stimulus presentation probability on accuracy and response times in an absolute identification task. Three schedules of presentation were used to investigate the interaction between presentation probability and stimulus position within the set. Data from individual participants indicated strong effects of presentation probability on both proportion correct and response times. The effects were moderated by the ubiquitous stimulus position effect. The accuracy and response time data were predicted by an exemplar-based model of perceptual cognition (Kent & Lamberts, 2005). The bow in discriminability was also attenuated when presentation probability for middle items was relatively high, an effect that will constrain future model development. The study provides evidence for item-specific learning in absolute identification. Implications for other theories of absolute identification are discussed. (PsycINFO Database Record PMID:26478959

  15. Characteristic length of the knotting probability revisited

    NASA Astrophysics Data System (ADS)

    Uehara, Erica; Deguchi, Tetsuo

    2015-09-01

    We present a self-avoiding polygon (SAP) model for circular DNA in which the radius of impermeable cylindrical segments corresponds to the screening length of double-stranded DNA surrounded by counter ions. For the model we evaluate the probability for a generated SAP with N segments having a given knot K through simulation. We call it the knotting probability of a knot K with N segments for the SAP model. We show that when N is large the most significant factor in the knotting probability is given by the exponentially decaying part exp(-N/NK), where the estimates of parameter NK are consistent with the same value for all the different knots we investigated. We thus call it the characteristic length of the knotting probability. We give formulae expressing the characteristic length as a function of the cylindrical radius rex, i.e. the screening length of double-stranded DNA.

  16. Teaching Elementary Probability Through its History.

    ERIC Educational Resources Information Center

    Kunoff, Sharon; Pines, Sylvia

    1986-01-01

    Historical problems are presented which can readily be solved by students once some elementary probability concepts are developed. The Duke of Tuscany's Problem; the problem of points; and the question of proportions, divination, and Bertrand's Paradox are included. (MNS)

  17. Neutron initiation probability in fast burst reactor

    SciTech Connect

    Liu, X.; Du, J.; Xie, Q.; Fan, X.

    2012-07-01

    Based on the probability balance of neutron random events in multiply system, the four random process of neutron in prompt super-critical is described and then the equation of neutron initiation probability W(r,E,{Omega},t) is deduced. On the assumption of static, slightly prompt super-critical and the two factorial approximation, the formula of the average probability of 'one' neutron is derived which is the same with the result derived from the point model. The MC simulation using point model is applied in Godiva- II and CFBR-II, and the simulation result of one neutron initiation is well consistent with the theory that the initiation probability of Godiva- II inverted commas CFBR-II burst reactor are 0.00032, 0.00027 respectively on the ordinary burst operation. (authors)

  18. Determining Probabilities by Examining Underlying Structure.

    ERIC Educational Resources Information Center

    Norton, Robert M.

    2001-01-01

    Discusses how dice games pose fairness issues that appeal to students and examines a structure for three games involving two dice in a way that leads directly to the theoretical probabilities for all possible outcomes. (YDS)

  19. EEG-directed connectivity from posterior brain regions is decreased in dementia with Lewy bodies: a comparison with Alzheimer's disease and controls.

    PubMed

    Dauwan, Meenakshi; van Dellen, Edwin; van Boxtel, Lotte; van Straaten, Elisabeth C W; de Waal, Hanneke; Lemstra, Afina W; Gouw, Alida A; van der Flier, Wiesje M; Scheltens, Philip; Sommer, Iris E; Stam, Cornelis J

    2016-05-01

    Directed information flow between brain regions might be disrupted in dementia with Lewy bodies (DLB) and relate to the clinical syndrome of DLB. To investigate this hypothesis, resting-state electroencephalography recordings were obtained in patients with probable DLB and Alzheimer's disease (AD), and controls (N = 66 per group, matched for age and gender). Phase transfer entropy was used to measure directed connectivity in the groups for the theta, alpha, and beta frequency band. A posterior-to-anterior phase transfer entropy gradient, with occipital channels driving the frontal channels, was found in controls in all frequency bands. This posterior-to-anterior gradient was largely lost in DLB in the alpha band (p < 0.05). In the beta band, posterior brain regions were less driving in information flow in AD than in DLB and controls. In conclusion, the common posterior-to-anterior pattern of directed connectivity in controls is disturbed in DLB patients in the alpha band, and in AD patients in the beta band. Disrupted alpha band-directed connectivity may underlie the clinical syndrome of DLB and differentiate between DLB and AD. PMID:27103525

  20. The spline probability hypothesis density filter

    NASA Astrophysics Data System (ADS)

    Sithiravel, Rajiv; Tharmarasa, Ratnasingham; McDonald, Mike; Pelletier, Michel; Kirubarajan, Thiagalingam

    2012-06-01

    The Probability Hypothesis Density Filter (PHD) is a multitarget tracker for recursively estimating the number of targets and their state vectors from a set of observations. The PHD filter is capable of working well in scenarios with false alarms and missed detections. Two distinct PHD filter implementations are available in the literature: the Sequential Monte Carlo Probability Hypothesis Density (SMC-PHD) and the Gaussian Mixture Probability Hypothesis Density (GM-PHD) filters. The SMC-PHD filter uses particles to provide target state estimates, which can lead to a high computational load, whereas the GM-PHD filter does not use particles, but restricts to linear Gaussian mixture models. The SMC-PHD filter technique provides only weighted samples at discrete points in the state space instead of a continuous estimate of the probability density function of the system state and thus suffers from the well-known degeneracy problem. This paper proposes a B-Spline based Probability Hypothesis Density (S-PHD) filter, which has the capability to model any arbitrary probability density function. The resulting algorithm can handle linear, non-linear, Gaussian, and non-Gaussian models and the S-PHD filter can also provide continuous estimates of the probability density function of the system state. In addition, by moving the knots dynamically, the S-PHD filter ensures that the splines cover only the region where the probability of the system state is significant, hence the high efficiency of the S-PHD filter is maintained at all times. Also, unlike the SMC-PHD filter, the S-PHD filter is immune to the degeneracy problem due to its continuous nature. The S-PHD filter derivations and simulations are provided in this paper.