Efficient search using posterior phone probability estimates.
Renals, Steve; Hochberg, Mike
1995-01-01
In this paper we present a novel, efficient search strategy for large vocabulary continuous speech recognition (LVCSR). The search algorithm, based on stack decoding, uses posterior phone probability estimates to substantially ...
Confidence measures from local posterior probability estimates
Williams, Gethin; Renals, Steve
1999-01-01
In this paper we introduce a set of related confidence measures for large vocabulary continuous speech recognition (LVCSR) based on local phone posterior probability estimates output by an acceptor HMM acoustic model. In ...
The Estimation of Tree Posterior Probabilities Using Conditional Clade Probability Distributions
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
Posterior Probability Matching and Human Perceptual Decision Making
Murray, Richard F.; Patel, Khushbu; Yee, Alan
2015-01-01
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
Posterior Probability Matching and Human Perceptual Decision Making.
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
Branch-length prior influences Bayesian posterior probability of phylogeny.
Yang, Ziheng; Rannala, Bruce
2005-06-01
The Bayesian method for estimating species phylogenies from molecular sequence data provides an attractive alternative to maximum likelihood with nonparametric bootstrap due to the easy interpretation of posterior probabilities for trees and to availability of efficient computational algorithms. However, for many data sets it produces extremely high posterior probabilities, sometimes for apparently incorrect clades. Here we use both computer simulation and empirical data analysis to examine the effect of the prior model for internal branch lengths. We found that posterior probabilities for trees and clades are sensitive to the prior for internal branch lengths, and priors assuming long internal branches cause high posterior probabilities for trees. In particular, uniform priors with high upper bounds bias Bayesian clade probabilities in favor of extreme values. We discuss possible remedies to the problem, including empirical and full Bayesian methods and subjective procedures suggested in Bayesian hypothesis testing. Our results also suggest that the bootstrap proportion and Bayesian posterior probability are different measures of accuracy, and that the bootstrap proportion, if interpreted as the probability that the clade is true, can be either too liberal or too conservative. PMID:16012111
Classifier Conditional Posterior Probabilities Robert P.W. Duin, David M.J. Tax
Duin, Robert P.W.
Classifier Conditional Posterior Probabilities Robert P.W. Duin, David M.J. Tax Pattern Recognition Classifiers based on probability density estimates can be used to find posterior probabilities for the objects to be classified. These probabilities can be used for rejection or for combining classifiers. Posterior
The development of posterior probability models in risk-based integrity modeling.
Thodi, Premkumar N; Khan, Faisal I; Haddara, Mahmoud R
2010-03-01
There is a need for accurate modeling of mechanisms causing material degradation of equipment in process installation, to ensure safety and reliability of the equipment. Degradation mechanisms are stochastic processes. They can be best described using risk-based approaches. Risk-based integrity assessment quantifies the level of risk to which the individual components are subjected and provides means to mitigate them in a safe and cost-effective manner. The uncertainty and variability in structural degradations can be best modeled by probability distributions. Prior probability models provide initial description of the degradation mechanisms. As more inspection data become available, these prior probability models can be revised to obtain posterior probability models, which represent the current system and can be used to predict future failures. In this article, a rejection sampling-based Metropolis-Hastings (M-H) algorithm is used to develop posterior distributions. The M-H algorithm is a Markov chain Monte Carlo algorithm used to generate a sequence of posterior samples without actually knowing the normalizing constant. Ignoring the transient samples in the generated Markov chain, the steady state samples are rejected or accepted based on an acceptance criterion. To validate the estimated parameters of posterior models, analytical Laplace approximation method is used to compute the integrals involved in the posterior function. Results of the M-H algorithm and Laplace approximations are compared with conjugate pair estimations of known prior and likelihood combinations. The M-H algorithm provides better results and hence it is used for posterior development of the selected priors for corrosion and cracking. PMID:20163559
Posterior probability distributions for Biot parameters from experimental data
NASA Astrophysics Data System (ADS)
Xu, Buye; Neilsen, Traci; Isakson, Marcia
2005-04-01
Reflectivity measurements can be used in inversion techniques to obtain estimates of the physical characteristics of seabed sediments. In addition, computation of posterior probability distributions (PPDs) [S. E. Dosso, J. Acoust. Soc. Am. 111, 129-142 (2002)] provide an uncertainty of each parameter estimate obtained by a simulated annealing inversion. In this work, PPDs are calculated for experimental reflection loss data to evaluate the sensitivities associated with the parameters in the Biot-Stoll poro-elastic model for sediments. The data comes from a lab tank experiment in which reflection loss from a sandy sediment was measured as a function of grazing angle for frequencies between 75 kHz and 150 kHz. The sampling for the PPDs is based on the least-squares error between simulated reflection coefficient data and values modeled with the reflection module of OASES. [H. Schmidt, ``OASES Version 2.1 User Guide and Reference Manual,'' Department of Ocean Engineering, Massachusetts Institute of Technology, 1997.] The PPDs resulting from the lab data are compared with those obtained for simulated data, and the effects of experimental error on the results are explored.
Frequency dependence of posterior probability distributions for Biot parameters
NASA Astrophysics Data System (ADS)
Neilsen, Tracianne B.; Isakson, Marcia; Xu, Buye
2005-04-01
The Biot-Stoll poro-elastic model for sediments is parameterized by 13 properties. Initial investigations indicate that the individual Biot parameters influence reflection loss differently depending on the frequency range of interest. A more extensive study of the frequency dependence of the parameter sensitivities is performed by computing posterior probability distributions (PPDs) [S. E. Dosso, J. Acoust. Soc. Am. 111, 129-142 (2002)] to determine which parameters most influence reflection loss for each frequency decade from 100 Hz to 1 MHz. The sampling for the PPDs is based on the least-squares error between simulated reflection coefficient data and values modeled with the reflection module of OASES. [H. Schmidt, ``OASES Version 2.1 User Guide and Reference Manual,'' Department of Ocean Engineering, Massachusetts Institute of Technology, 1997.] The PPDs provide a quantitative value of the uncertainty in the optimum parameter estimates obtained by sampling or inversion techniques. A good value of the uncertainty is critical if one wants to use parameter estimates obtained with data from one frequency range to predict acoustic response for a different frequency range. [Work supported by the ONR.
Hanson, K.M.
1991-01-01
An optimal solution to the problem of making binary decisions about a local region of a reconstruction is provided by the Bayesian method. The decision is made on the basis of the ratio of the posterior probabilities for the two hypotheses. The full Bayesian procedure requires an integration of the posterior probability over all possible values of the image outside the local region being analyzed. In the present work, this full treatment is replaced by the maximum value of the posterior probability obtained when the exterior region is varied, but the interior is fixed at both hypothesized functional forms. A Monte Carlo procedure is employed to evaluate the usefulness of the technique in a signal-known-exactly detection task in a noisy four-view tomographic reconstruction situation. 27 refs., 2 figs., 1 tab.
Performance of the Rayleigh task based on the posterior probability of tomographic reconstructions
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.
Chikkagoudar, Satish; Roshan, Usman; Livesay, Dennis
2007-01-01
Probalign computes maximal expected accuracy multiple sequence alignments from partition function posterior probabilities. To date, Probalign is among the very best scoring methods on the BAliBASE, HOMSTRAD and OXBENCH benchmarks. Here, we introduce eProbalign, which is an online implementation of the approach. Moreover, the eProbalign web server doubles as an online platform for post-alignment analysis. The heart-and-soul of the post-alignment functionality is the Probalign Alignment Viewer applet, which provides users a convenient means to manipulate the alignments by posterior probabilities. The viewer can also be used to produce graphical and text versions of the output. The eProbalign web server and underlying Probalign source code is freely accessible at http://probalign.njit.edu PMID:17485479
Chikkagoudar, Satish; Roshan, Usman; Livesay, Dennis
2007-07-01
Probalign computes maximal expected accuracy multiple sequence alignments from partition function posterior probabilities. To date, Probalign is among the very best scoring methods on the BAliBASE, HOMSTRAD and OXBENCH benchmarks. Here, we introduce eProbalign, which is an online implementation of the approach. Moreover, the eProbalign web server doubles as an online platform for post-alignment analysis. The heart-and-soul of the post-alignment functionality is the Probalign Alignment Viewer applet, which provides users a convenient means to manipulate the alignments by posterior probabilities. The viewer can also be used to produce graphical and text versions of the output. The eProbalign web server and underlying Probalign source code is freely accessible at http://probalign.njit.edu. PMID:17485479
Separating Occluded Humans by Bayesian Pixel Classifier with Re-weighted Posterior Probability
Daehwan Kim; Yeonho Kim; Daijin Kim
\\u000a This paper proposes a Bayesian pixel classification method with re-weighted posterior probability for separating multiple\\u000a occluded humans. We separate the occluded humans by considering the occlusion region as a pixel classification problem. First,\\u000a we detect an isolated human using the human detector. Then we divide it into three body parts (head, torso, and legs) using\\u000a the body part detector, and
Satish Chikkagoudar; Usman Roshan; Dennis R. Livesay
2007-01-01
Probalign computes maximal expected accuracy multiple sequence alignments from partition function posterior probabilities. To date, Probalign is among the very best scoring methods on the BAliBASE, HOMSTRAD, and OXBENCH benchmarks. Here, we introduce eProbalign, which is an online implementation of the approach. Moreover, the eProbalign webserver doubles as an online platform for post-alignment analysis. The heart-and-soul of the post-alignment functionality
Casaseca-de-la-Higuera, Pablo; Ignacio Arribas, Juan; Munoz-Moreno, Emma; Alberola-Lopez, Carlos
2005-01-01
Automatic detection of microcalcifications in mammograms constitutes a helpful tool in breast cancer diagnosis. Radiologist's confidence level on microcalcification detection would be improved if a probability estimate of its presence could be obtained from computer-aided diagnosis. In this paper we explore detection performance of a simple Bayesian classifier based on Gaussian mixture probability density functions (pdf). Posterior probability of microcalcification presence may be estimated from the probabilistic model. Two model selection algorithms have been tested, one based on the Minimum Message Length criterion and the other on discriminative criteria obtained from the classifier performance. In addition, we propose a complementing model selection algorithm in order to improve the initial system performance obtained with these methods. Simulation results show that our model gets a good compromise between classification performance and probability estimation accuracy. PMID:17282108
Salemis, Nikolaos S; Grapatsas, Konstantinos; Matzoukas, Ioannis; Lagoudianakis, Emmanuel
2015-03-01
Solitary cecal diverticulitis is a rare cause of abdominal pain in Western countries. The preoperative diagnosis is very difficult to establish and most patients are operated on with a presumptive diagnosis of acute appendicitis based on clinical grounds. We describe a very rare case of perforated posterior cecal diverticulum and discuss the challenges in establishing a correct preoperative diagnosis. We conclude that although very rare, the possibility of perforated posteriorcecal diverticulum should always be considered in the differential diagnosis of patients presenting with atypical clinical manifestations of acute appendicitis. A perforation of a posterior cecal diverticulum maybe associated with a mild clinical course without signs of peritonitis. Athorough preoperative evaluation including a computed tomography scan is essential in order to establish a correct preoperative diagnosis which is of utmost importance for treatment planning in the emergency setting. Simple diverticulectomy is an effective surgical treatment in the absence of extensive inflammatory changes and when a colonic tumor can be ruled out. PMID:25245284
Roshan, Usman; Chikkagoudar, Satish; Livesay, Dennis R
2008-01-01
Background Identification of RNA homologs within genomic stretches is difficult when pairwise sequence identity is low or unalignable flanking residues are present. In both cases structure-sequence or profile/family-sequence alignment programs become difficult to apply because of unreliable RNA structures or family alignments. As such, local sequence-sequence alignment programs are frequently used instead. We have recently demonstrated that maximal expected accuracy alignments using partition function match probabilities (implemented in Probalign) are significantly better than contemporary methods on heterogeneous length protein sequence datasets, thus suggesting an affinity for local alignment. Results We create a pairwise RNA-genome alignment benchmark from RFAM families with average pairwise sequence identity up to 60%. Each dataset contains a query RNA aligned to a target RNA (of the same family) embedded in a genomic sequence at least 5K nucleotides long. To simulate common conditions when exact ends of an ncRNA are unknown, each query RNA has 5' and 3' genomic flanks of size 50, 100, and 150 nucleotides. We subsequently compare the error of the Probalign program (adjusted for local alignment) to the commonly used local alignment programs HMMER, SSEARCH, and BLAST, and the popular ClustalW program with zero end-gap penalties. Parameters were optimized for each program on a small subset of the benchmark. Probalign has overall highest accuracies on the full benchmark. It leads by 10% accuracy over SSEARCH (the next best method) on 5 out of 22 families. On datasets restricted to maximum of 30% sequence identity, Probalign's overall median error is 71.2% vs. 83.4% for SSEARCH (P-value < 0.05). Furthermore, on these datasets Probalign leads SSEARCH by at least 10% on five families; SSEARCH leads Probalign by the same margin on two of the fourteen families. We also demonstrate that the Probalign mean posterior probability, compared to the normalized SSEARCH Z-score, is a better discriminator of alignment quality. All datasets and software are available online. Conclusion We demonstrate, for the first time, that partition function match probabilities used for expected accuracy alignment, as done in Probalign, provide statistically significant improvement over current approaches for identifying distantly related RNA sequences in larger genomic segments. PMID:18226231
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
NEW ACCEPT\\/REJECT METHODS FOR INDEPENDENT SAMPLING FROM POSTERIOR PROBABILITY DISTRIBUTIONS
Luca Martino
2009-01-01
Rejection sampling (RS) is a well-known method to generate (pseudo-)random samples from arbitrary probability distributions that enjoys important applications, either by itself or as a tool in more sophisticated Monte Carlo techniques. Unfortunately, the use of RS techniques demands the calculation of tight upper bounds for the ratio of the target probability density function (pdf) o ver the proposal density
A simple, accurate method to calculate spread-spectrum multiple-access error probabilities
Jack M. Holtzman
1992-01-01
The exact calculation of error probabilities for direct-sequence spread-spectrum multiple-access (DS\\/SSMA) systems has been addressed in the literature. The exact calculation is computationally difficult, so emphasis has been on approximations and bounds. One particularly attractive approximation is to just use a signal-to-noise ratio in a Gaussian approximation, the `standard approximation'. Unfortunately, that approximation is not generally accurate enough. An improved
Albers, Cornelis A; Stankovich, Jim; Thomson, Russell; Bahlo, Melanie; Kappen, Hilbert J
2008-03-01
We propose an analytical approximation method for the estimation of multipoint identity by descent (IBD) probabilities in pedigrees containing a moderate number of distantly related individuals. We show that in large pedigrees where cases are related through untyped ancestors only, it is possible to formulate the hidden Markov model of the Lander-Green algorithm in terms of the IBD configurations of the cases. We use a first-order Markov approximation to model the changes in this IBD-configuration variable along the chromosome. In simulated and real data sets, we demonstrate that estimates of parametric and nonparametric linkage statistics based on the first-order Markov approximation are accurate. The computation time is exponential in the number of cases instead of in the number of meioses separating the cases. We have implemented our approach in the computer program ALADIN (accurate linkage analysis of distantly related individuals). ALADIN can be applied to general pedigrees and marker types and has the ability to model marker-marker linkage disequilibrium with a clustered-markers approach. Using ALADIN is straightforward: It requires no parameters to be specified and accepts standard input files. PMID:18319071
Albers, Cornelis A.; Stankovich, Jim; Thomson, Russell; Bahlo, Melanie; Kappen, Hilbert J.
2008-01-01
We propose an analytical approximation method for the estimation of multipoint identity by descent (IBD) probabilities in pedigrees containing a moderate number of distantly related individuals. We show that in large pedigrees where cases are related through untyped ancestors only, it is possible to formulate the hidden Markov model of the Lander-Green algorithm in terms of the IBD configurations of the cases. We use a first-order Markov approximation to model the changes in this IBD-configuration variable along the chromosome. In simulated and real data sets, we demonstrate that estimates of parametric and nonparametric linkage statistics based on the first-order Markov approximation are accurate. The computation time is exponential in the number of cases instead of in the number of meioses separating the cases. We have implemented our approach in the computer program ALADIN (accurate linkage analysis of distantly related individuals). ALADIN can be applied to general pedigrees and marker types and has the ability to model marker-marker linkage disequilibrium with a clustered-markers approach. Using ALADIN is straightforward: It requires no parameters to be specified and accepts standard input files. PMID:18319071
Magee, Joseph W.
Publisher's Note: "Accurate Atomic Transition Probabilities for Hydrogen, Helium, and Lithium" J and Technology, Gaithersburg, Maryland 20899, USA Received 22 September 2009; published online 31 December 2009 published online on 24 June 2009 with incorrect breaks in the ranges in Table 14. This error resulted
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.
NSDL National Science Digital Library
Ms. Thompson
2008-12-01
This is introduction into probability. This project allows students to explore with probability, the days following gives students a further look into probability. Today, you are going to experiment with probability. Go to the site An introduction into probability and read the first three sections, the last sections is the one with the picture of the coins. After you have read a little bit about probability, you now get to explore probability through some games. Start ...
NSDL National Science Digital Library
Mrs. Marsh
2006-11-16
Using different probabilities Help cybersquad clean up the buggy mess. Which bugs will Probability show up? Try out all the probability Possibilities. Find the answers to these Ratio activities. Practice Ratios and Proportions. ...
Gross, Louis J.
Drug testing example for conditional probability Suppose that a drug test for an illegal drug is such that it is 98% accurate in the case of a user of that drug (e.g. it produces a positive result with probability .98 in the case that the tested individual uses the drug) and 90% accurate in the case of a non
NSDL National Science Digital Library
2011-01-18
This application demomstrates simple probability concepts by having student rank the probability of an event on a probability line (from impossible to certain). After several trials the application then allows students to complete a simulation and collect data based on the probability task (retrieving balls from a machine). Several guiding questions are provided throughout the activity to encourage student dialogue.
Hindsight bias: an impediment to accurate probability estimation in clinicopathologic conferences.
Dawson, N V; Arkes, H R; Siciliano, C; Blinkhorn, R; Lakshmanan, M; Petrelli, M
1988-01-01
Although clinicopathologic conferences (CPCs) have been valued for teaching differential diagnosis, their instructional value may be compromised by hindsight bias. This bias occurs when those who know the actual diagnosis overestimate the likelihood that they would have been able to predict the correct diagnosis had they been asked to do so beforehand. Evidence for the presence of the hindsight bias was sought among 160 physicians and trainees attending four CPCs. Before the correct diagnosis was announced, half of the conference audience estimated the probability that each of five possible diagnoses was correct (foresight subjects). After the correct diagnosis was announced the remaining (hindsight) subjects estimated the probability they would have assigned to each of the five possible diagnoses had they been making the initial differential diagnosis. Only 30% of the foresight subjects ranked the correct diagnosis as first, versus 50% of the hindsight subjects (p less than 0.02). Although less experienced physicians consistently demonstrated the hindsight bias, more experienced physicians succumbed only on easier cases. PMID:3185178
NSDL National Science Digital Library
Ms. Banks
2005-05-11
What are the chances? What is probability? Math Glossary What are the chances that you will get a baby brother or a baby sister? Boy or Girl? If you flip more than one coin, what are the combinations you could get? What are the chances you will get each combination? Probability in Flipping Coins ...
2013-01-01
Background In investigating differentially expressed genes or other selected features, researchers conduct hypothesis tests to determine which biological categories, such as those of the Gene Ontology (GO), are enriched for the selected features. Multiple comparison procedures (MCPs) are commonly used to prevent excessive false positive rates. Traditional MCPs, e.g., the Bonferroni method, go to the opposite extreme: strictly controlling a family-wise error rate, resulting in excessive false negative rates. Researchers generally prefer the more balanced approach of instead controlling the false discovery rate (FDR). However, the q-values that methods of FDR control assign to biological categories tend to be too low to reliably estimate the probability that a biological category is not enriched for the preselected features. Thus, we study an application of the other estimators of that probability, which is called the local FDR (LFDR). Results We considered five LFDR estimators for detecting enriched GO terms: a binomial-based estimator (BBE), a maximum likelihood estimator (MLE), a normalized MLE (NMLE), a histogram-based estimator assuming a theoretical null hypothesis (HBE), and a histogram-based estimator assuming an empirical null hypothesis (HBE-EN). Since NMLE depends not only on the data but also on the specified value of ?0, the proportion of non-enriched GO terms, it is only advantageous when either ?0 is already known with sufficient accuracy or there are data for only 1 GO term. By contrast, the other estimators work without specifying ?0 but require data for at least 2 GO terms. Our simulation studies yielded the following summaries of the relative performance of each of those four estimators. HBE and HBE-EN produced larger biases for 2, 4, 8, 32, and 100 GO terms than BBE and MLE. BBE has the lowest bias if ?0 is 1 and if the number of GO terms is between 2 and 32. The bias of MLE is no worse than that of BBE for 100 GO terms even when the ideal number of components in its underlying mixture model is unknown, but has high bias when the number of GO terms is small compared to the number of estimated parameters. For unknown values of ?0, BBE has the lowest bias for a small number of GO terms (2-32 GO terms), and MLE has the lowest bias for a medium number of GO terms (100 GO terms). Conclusions For enrichment detection, we recommend estimating the LFDR by MLE given at least a medium number of GO terms, by BBE given a small number of GO terms, and by NMLE given either only 1 GO term or precise knowledge of ?0. PMID:23497228
Michalet, Xavier
Fig. S1: Study of the histogram of the distribution of values { };0 ;1 500i N i N N represented in Fig. 2. A. Logarithm of the posterior probability (LPP) of bin number N (as defined in ref. 36 ). The maximum is obtained for N = 1. B: Histogram of the distribution with 1, 10 and 100 bins. The distribution
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…
Gross, Louis J.
Drug testing Example for Conditional Probability and Bayes Theorem Suppose that a drug test for an illegal drug is such that it is 98% accurate in the case of a user of that drug (e.g. it produces a positive result with probability .98 in the case that the tested individual uses the drug) and 90% accurate
Spondylolisthesis and posterior instability.
Niggemann, P; Simons, P; Kuchta, J; Beyer, H K; Frey, H; Grosskurth, D
2009-04-01
We present the case of a patient with a spondylolisthesis of L5 on S1 due to spondylolysis at the level L5/S1. The vertebral slip was fixed and no anterior instability was found. Using functional magnetic resonance imaging (MRI) in an upright MRI scanner, posterior instability at the level of the spondylolytic defect of L5 was demonstrated. A structure, probably the hypertrophic ligament flava, arising from the spondylolytic defect was displaced toward the L5 nerve root, and a bilateral contact of the displaced structure with the L5 nerve root was shown in extension of the spine. To our knowledge, this is the first case described of posterior instability in patients with spondylolisthesis. The clinical implications of posterior instability are unknown; however, it is thought that this disorder is common and that it can only be diagnosed using upright MRI. PMID:19253068
Hinton, Geoffrey E.
of variables usually in lower case: x We will write p(x) to mean probability(X = x). #15; Sample Space believe in x. #15; Ensemble: random variable + sample space+ probability function Expectations, Moments xp(x), variance = P x (x E[x]) 2 p(x) #15; Moments are expectations of higher order powers. (Mean
Daly, Megan E.; Luxton, Gary [Department of Radiation Oncology, Stanford University, Stanford, CA (United States); Choi, Clara Y.H. [Department of Neurosurgery, Stanford University, Stanford, CA (United States); Gibbs, Iris C. [Department of Radiation Oncology, Stanford University, Stanford, CA (United States); Chang, Steven D.; Adler, John R. [Department of Neurosurgery, Stanford University, Stanford, CA (United States); Soltys, Scott G., E-mail: sgsoltys@stanford.edu [Department of Radiation Oncology, Stanford University, Stanford, CA (United States)
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.
Evaluation of posterior fossa lesions by computer assisted tomography (CAT).
Lott, T; El Gammal, T; Volcan, I
1977-07-01
Valuable neuroradiologic information can be obtained with routine examination of the posterior fossa by computer assisted tomography (CAT). The diagnosis can be difficult in the posterior fossa due to the relatively small size of the compartment and its proximities to large bony masses and air in the mastoid cells. However, many lesions can be accurately diagnosed when close attention is given to anatomic detail and the frequent use of contrast enhancement. We introduced a new CAT classification of posterior fossa neoplasms. PMID:877637
B. V. Agirdir; M. Sindel; G. Arslan; F. B. Yildirim; E. I. Balkan; O. Dinç
2001-01-01
The canal of the posterior ampullar nerve is located between the inferior part of the internal acoustic meatus and ampulla of the posterior semicircular canal. It permits a more accurate localisation of the underlying labyrinth in inner-ear surgery. An anatomical and radiological study was undertaken to determine the importance the relationship between the canal and the labyrinth. Ten dry and
Posterior-based confidence measures for spoken term detection
Wang, Dong; Tejedor, Javier; Frankel, Joe; King, Simon
2009-01-01
Confidence measures play a key role in spoken term detection (STD) tasks. The confidence measure expresses the posterior probability of the search term appearing in the detection period, given the speech. Traditional ...
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).
Joseph B. Myers; Sakiko Oyama; Craig A. Wassinger; Robert D. Ricci; John P. Abt; Kevin M. Conley; Scott M. Lephart
2007-01-01
Background: Posterior shoulder tightness with subsequent loss of humeral internal rotation range of motion has been linked to upper extremity lesions in overhead athletes. A valid clinical assessment is necessary to accurately identify posterior shoulder tightness as a contributor to injury.Purpose: To describe a modified supine assessment of posterior shoulder tightness by establishing the reliability, precision, clinical accuracy, and validity
Posterior Cranial Fossa Meningiomas*
Javalkar, Vijayakumar; Banerjee, Anirban Deep; Nanda, Anil
2012-01-01
This study evaluated the outcomes, complications, and recurrence rates of posterior cranial fossa meningiomas. We retrospectively reviewed our surgical experience with 64 posterior cranial fossa meningiomas. Mean age was 56 years with a female preponderance (67.2%). Headache was the most common symptom. Retrosigmoid approach was the commonest surgical procedure (23.4%). The incidence of cranial nerve related complications was 28%. Postoperatively facial nerve weakness was observed in 11%. The incidence of cerebrospinal fluid leak was 4.6%. Gross total resection was achieved in 37 patients (58%). Sixteen patients (25%) with residual tumors underwent Gamma knife radiosurgery. Recurrence or tumor progression was observed in 12 patients (18.7%). Operative mortality was 3.1%. At their last follow-up, 93% of the cases achieved Glasgow Outcome Scale scores 4 or 5. Total excision is the ideal goal which can be achieved with meningiomas located in certain location, such as lateral convexity, but for other posterior fossa meningiomas the close proximity of critical structures is a major obstacle in achieving this goal. In practicality, a balance between good functional outcome and extent of resection is important for posterior cranial fossa meningiomas in proximity to critical structures. PMID:23372989
Posterior vertebral rim fractures
I BEGGS; J ADDISON
Fracture of the posterior vertebral endplate is a cause of low back pain in adolescents and young adults. Clinically it resembles an acute disc prolapse with low back pain and radiculopa- thy, but may present with neurogenic claudication due to spinal stenosis in older patients. The lesions may be incidental findings. Plain radiographs are diagnostic in about 40% of cases.
Divyesh Y. Desai; Peter M. Cuckow
Posterior urethral valves (PUV) remains the most common cause of bladder outflow obstruction in male infants. The condition\\u000a has an estimated incidence of 1\\/4000 to 1\\/5000 live births. It is a panurinary tract disorder with a variable spectrum of\\u000a severity that can affect both the upper and lower urinary tract.1,2
Why should we report posterior fossa emissary veins?
Pekçevik, Yeliz; Pekçevik, R?dvan
2014-01-01
Posterior fossa emissary veins are valveless veins that pass through cranial apertures. They participate in extracranial venous drainage of the posterior fossa dural sinuses. The mastoid emissary vein, condylar veins, occipital emissary vein, and petrosquamosal sinus are the major posterior fossa emissary veins. We believe that posterior fossa emissary veins can be detected by radiologists before surgery with a thorough understanding of their anatomy. Describing them using temporal bone computed tomography (CT), CT angiography, and cerebral magnetic resonance (MR) venography examinations results in more detailed and accurate preoperative radiological interpretation and has clinical importance. This pictorial essay reviews the anatomy of the major and clinically relevant posterior fossa emissary veins using high-resolution CT, CT angiography, and MR venography images and discusses the clinical importance of reporting these vascular variants. PMID:24047723
Solyga, Volker Moræus; Western, Elin; Solheim, Hanne; Hassel, Bjørnar; Kerty, Emilia
2015-06-01
BACKGROUND Posterior cortical atrophy is a neurodegenerative condition with atrophy of posterior parts of the cerebral cortex, including the visual cortex and parts of the parietal and temporal cortices. It presents early, in the 50s or 60s, with nonspecific visual disturbances that are often misinterpreted as ophthalmological, which can delay the diagnosis. The purpose of this article is to present current knowledge about symptoms, diagnostics and treatment of this condition.METHOD The review is based on a selection of relevant articles in PubMed and on the authors' own experience with the patient group.RESULTS Posterior cortical atrophy causes gradually increasing impairment in reading, distance judgement, and the ability to perceive complex images. Examination of higher visual functions, neuropsychological testing, and neuroimaging contribute to diagnosis. In the early stages, patients do not have problems with memory or insight, but cognitive impairment and dementia can develop. It is unclear whether the condition is a variant of Alzheimer's disease, or whether it is a separate disease entity. There is no established treatment, but practical measures such as the aid of social care workers, telephones with large keypads, computers with voice recognition software and audiobooks can be useful.INTERPRETATION Currently available treatment has very limited effect on the disease itself. Nevertheless it is important to identify and diagnose the condition in its early stages in order to be able to offer patients practical assistance in their daily lives. PMID:26037756
Posterior fossa metastasis in lung cancer patients with vertigo
Shunji Hiyashi; Po-Wen Cheng; Yi-Ho Young
2011-01-01
This study investigated whether vertiginous attacks indicate a high probability for posterior fossa metastasis in lung cancer\\u000a patients. Twenty-five lung cancer patients having vertiginous episodes were enrolled in this study. All patients underwent\\u000a a battery of audiovestibular function testing and MR imaging study. Ten (40%) of 25 lung cancer patients with vertigo were\\u000a proven to have posterior fossa metastasis (PM1
Posterior Cervical Foraminotomy and Laminectomy
John E. O’Toole; Kurt M. Eichholz; Richard G. Fessler
\\u000a Posterior decompressive procedures are fundamental tools in the surgical treatment of symptomatic cervical degenerative spine\\u000a disease [1–4]. Even as anterior cervical procedures have gained prominence, posterior cervical laminoforaminotomy still provides\\u000a symptomatic relief in 92–97% of patients with radiculopathy from foraminal stenosis or lateral herniated discs [3, 5]. Similarly,\\u000a posterior cervical decompression for cervical stenosis achieves neurological improvement in 62.5–83% of
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.
A GENERAL FORMULATION FOR LEARNING MULTI-CLASS POSTERIOR PROBABILITIES
Adali, Tulay
observations [2]. Particularly, since it al- lows for inclusion of dependent observations, missing data for applica- tion to problems in which time-ordering is essential (e.g. time-series problems), or can be conveniently defined [l]. Partial likelihood can be defined as follows: Consider a time series {xn}, n = 1
Posterior fossa ependymomas in adults
C. Davis; L. Symon
1986-01-01
Summary Sixteen patients with posterior fossa ependymomas are presented. This tumour is relatively uncommon in adults and is usually associated with a relatively “benign” course when compared with other posterior fossa glial tumours. The natural history and treatment of these tumours is discussed.
Gossypiboma mimicking posterior urethral stricture
Kumar, Bindey; Kumar, Prem; Sinha, Sanjay Kumar; Sinha, Neelam; Hasan, Zaheer; Thakur, Vinit Kumar; Anand, Utpal; Priyadarshi, Rajiv Nayan; Mandal, Manish
2013-01-01
INTRODUCTION Foreign bodies in the urogenital tract are not uncommon. Hairpins, glass rods, umbilical tapes, ball point pen are described in lower urogenital tract. Retained gauze piece (gossypiboma) in posterior urethra may cause diagnostic dilemma. Symptoms and investigations may mimic stricture of posterior urethra. PRESENTATION OF CASE Two cases of retained gauze pieces in the urethra are described here. The micturating cystourethrogram was suggestive of posterior urethral stricture. DISCUSSION Two cases described here had retained gauze piece as a cause of filling defect and abnormal appearance in the micturating cystourethrogram. Gossypiboma may be a possibility where posterior urethral stricture are seen after previous surgery in paediatric age group. CONCLUSION In the setting of previous urogenital surgery gossypiboma should be kept in the differential diagnosis where posterior urethral stricture are seen in the paediatric age group. PMID:23500749
Posterior reversible encephalopathy syndrome.
Lamy, C; Oppenheim, C; Mas, J L
2014-01-01
Posterior reversible encephalopathy syndrome (PRES) is a recently proposed cliniconeuroradiologic entity with several well-known causes, such as hypertensive encephalopathy, eclampsia, and the use of cytotoxic and immunosuppressive drugs, as well as some causes more recently described. PRES is characterized by neuroimaging findings of reversible vasogenic subcortical edema without infarction. The pathogenesis is incompletely understood. Two opposing hypotheses are commonly cited, but the issue is controversial: (1) the current more popular theory suggests that severe hypertension exceeds the limits of autoregulation, leading to breakthrough brain edema; (2) the earlier original theory suggests that hypertension leads to cerebral autoregulatory vasoconstriction, ischemia, and subsequent brain edema. The clinical syndrome of PRES typically involves headache, encephalopathy, visual symptoms, and seizures. The clinical presentation is often nonspecific, and therefore the diagnosis of PRES has come to increasingly rely on magnetic resonance imaging (MRI) abnormalities consistent with PRES with documented recovery clinically and on repeated neuroimaging. The diagnosis has important therapeutic and prognostic implications because the reversibility of the clinical and radiologic abnormalities is contingent on the prompt control of blood pressure and/or discontinuing the offending drug. PMID:24365441
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…
NSDL National Science Digital Library
Zollman, Dean
This resource shows the relation between quantum wave functions and probabilities. The user can draw a 1D wavefunction, and observe the resultant probability distribution. Both the probability density at a single point and the probability in any interval can be measured.
On the distributions of bootstrap support and posterior distributions for a star tree.
Susko, Edward
2008-08-01
Several authors have recently noted that when data are generated from a star topology, posterior probabilities can often be very large, even with arbitrarily large sequence lengths. This is counter to intuition, which suggests convergence to the limit of equal probability for each topology. Here the limiting distributions of bootstrap support and posterior probabilities are obtained for a four-taxon star tree. Theoretical results are given, providing confirmation that this counterintuitive phenomenon holds for both posterior probabilities and bootstrap support. For large samples the limiting results for posterior probabilities are the same regardless of the prior. With equal-length terminal edges, the limiting distribution is similar but not the same across different choices for the lengths of the edges. In contrast to previous results, the case of unequal lengths of terminal edges is considered. With two long edges, the posterior probability of the tree with long edges together tends to be much larger. Using the neighbor-joining algorithm, with equal edge lengths, the distribution of bootstrap support tends to be qualitatively comparable to posterior probabilities. As with posterior probabilities, when two of the edges are long, bootstrap support for the tree with long branches together tends to be large. The bias is less pronounced, however, as the distribution of bootstrap support gets close to uniform for this tree, whereas posterior probabilities are much more likely to be large. Our findings for maximum likelihood estimation are based entirely on simulation and in contrast suggest that bootstrap support tends to be fairly constant across edge-length choices. PMID:18709598
NSDL National Science Digital Library
Anderson-Cook, C.
The applet, created by Virginia Tech's Department of Statistics, allows you see how probabilities are determined from the exponential distribution. The user determines the mean of the distribution and the limits of probability. Three different probability expressions are available. Click "Calculate" to see the pdf and the cdf. The probability is highlighted in green on the pdf. This is a nice reference tool for anyone studying statistics.
NSDL National Science Digital Library
Siegrist, Kyle
Created by Kyle Siegrist of the University of Alabama-Huntsville, this is an online, interactive lesson on probability spaces. The resource provides examples, exercises, and applets that cover conditional probability, independence, and several modes of convergence that are appropriate for random variables. This section also covers probability space, the paradigm of a random experiment and its mathematical model as well as sample spaces, events, random variables, and probability measures. This is the second of seventeen different statistics lessons provided by Siegrist.
NSDL National Science Digital Library
Ms. Cate
2008-04-23
Probability is used to determine the likeliness of an event. Use these games to test your knowledge of this skill. You can adjust this spinner and determine the probability of the pointer landing in a certain sector. Try picking different colored marbles out of the box and determine the probability of each. Find the prize hidden behind each Door. ...
[Urinothorax: rare complication of neonatal sectioned posterior urethral valve].
Gouli, J-C; Merrot, T; Chaumoitre, K; Faure, A; Michel, F; Alessandrini, P
2011-02-01
We report a newborn aged 19 days, carrying a posterior urethral valve antenatal screening in which developed 7 days after the entire section of the valve, a compressive urinothorax in connection with a perirenal urinoma. Pleural and bladder drainage has a surrender of effusions and a healing of the renal parenchyma. The thoracic urine effusion is a very rare complication of a posterior urethral valve with perirenal urinoma. This probably results from a rupture of a fornix dysplastic by hypertension of the urinary tract. The authors emphasize the unusual discovery of this disease by breathing problems and his delayed character after resection of the obstruction in the neonatal period. PMID:21296284
Posterior crossbite - treatment and stability
de ALMEIDA, Renato Rodrigues; de ALMEIDA, Marcio Rodrigues; OLTRAMARI-NAVARRO, Paula Vanessa Pedron; CONTI, Ana Cláudia de Castro Ferreira; NAVARRO, Ricardo de Lima; MARQUES, Henry Victor Alves
2012-01-01
Posterior crossbite is defined as an inadequate transversal relationship of maxillary and mandibular teeth. Even when eliminating the etiologic factors, this malocclusion does not have a spontaneous correction, and should be treated with maxillary expansion as early as possible. This treatment aims at providing a better tooth/skeletal relationship, thereby improving masticatory function, and establishing a symmetrical condyle/fossa relationship. Should posterior crossbite not be treated early, it may result in skeletal changes, demanding a more complex approach. Additionally, an overcorrection expansion protocol should be applied in order to improve the treatment stability. Although the literature has reported a high rate of relapse after maxillary expansion, the goal of this study was to demonstrate excellent stability of the posterior crossbite correction 21 years post treatment. PMID:22666850
Bladder neck incompetence at posterior urethroplasty
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
NSDL National Science Digital Library
Anderson-Cook, C.
The applet, created by Virginia Tech's Department of Statistics, allows you to see how the T distribution is related to the Standard Normal distribution by calculating probabilities. The T distribution is primarily used to make inferences on a Normal mean when the variance is unknown. If the variance is known inference on the mean can be done using the Standard Normal. The user has a choice of three different probability expressions, then can change the degrees of freedom and the limits of probability.
Primary myelolipoma in posterior mediastinum
Xiong, Yan; Wang, Yong
2014-01-01
Myelolipoma in posterior mediastinum is indeed rare. As a benign tumor, it consists of mature fat with scattered foci of haematopoietic elements resembling bone marrow. The computed tomography (CT) and magnetic resonance imaging (MRI) are effective methods to detect them, while the definite diagnosis still depends on pathological diagnosis. Up to now, there is no standard treatment for this disease. Surgery is thought to be the best choice in some literatures reports. In this paper, two patients with primary posterior mediastinal tumor are reported, both of whom were underwent Video-assisted thoracoscopic surgery (VATS). Postoperative pathological diagnosis was myelolipoma. PMID:25276393
NSDL National Science Digital Library
Stark, Philip B.
This tool lets you calculate the probability that a random variable X is in a specified range, for a variety of probability distributions for X: the normal distribution, the binomial distribution with parameters n and p, the chi-square distribution, the exponential distribution, the geometric distribution, the hypergeometric distribution, the negative binomial distribution, the Poisson distribution, and Student's t-distribution. The first choice box lets you select a probability distribution. Depending on the distribution you select, text areas will appear for you to enter the values of the parameters of the distribution. Parameters that are probabilities (e.g., the chance of success in each trial for a binomial distribution) can be entered either as decimal numbers between 0 and 1, or as percentages. If you enter a probability as a percentage, be sure to include the percent sign (%) after the number.
[Posterior tibial tenoscopy. Case report].
Cuélar-Avaroma, A; King-Hayata, M; Martínez-de Anda, M C; King-Martinez, A C
2014-01-01
Posterior tibial tendinitis occurs commonly in patients involved in sports activities. It may result from either excessive use or sudden overload of the tendon. This tendinitis may also occur in patients with systemic inflammatory conditions and is classified as posterior tibial tendon dysfunction stage I. Initial treatment, which has produced good results, is based on immobilization and rehabilitation. In cases without clinical improvement or in which tendinitis is associated with partial tendon rupture, open techniques may be used to perform tenosynovectomy and tendon revisions to improve painful symptoms. With the advent of minimally invasive techniques broad tendon revisions may be done that cause minimal damage or they may be combined with traditional techniques in cases of partial rupture. This paper describes the clinical case of a 35 year-old female patient with posterior tibial pathology and chronic pain. She underwent posterior tibial tenoscopy and was followed-up postoperatively for 24 months. Endoscopic and/or tenoscopic treatment is a simple and reproducible technique. We obtained excellent functional and cosmetic results in this patient. We need larger case series of patients subjected to this treatment. PMID:26016290
Predicting oculomotor behaviour from correlated populations of posterior parietal neurons
Graf, Arnulf B. A.; Andersen, Richard A.
2014-01-01
Oculomotor function critically depends on how signals representing saccade direction and eye position are combined across neurons in the lateral intraparietal area (LIP) of the posterior parietal cortex. Here we show that populations of parietal neurons exhibit correlated variability, and that using these interneuronal correlations yields oculomotor predictions that are more accurate and also less uncertain. The structure of LIP population responses is therefore essential for reliable read-out of oculomotor behaviour. PMID:25613525
NSDL National Science Digital Library
PhET at University of Colorado
2010-08-02
The students will play a classic game from a popular show. Through this they will see the probabilty that the ball will land each of the numbers with more accurate results coming from repeated testing.
Joos, Zachary P; Adesina, Ore-Ofe O; Katz, Bradley J
2014-06-01
We present the magnetic resonance imaging findings of posterior ischemic optic neuropathy in a patient with posterior reversible encephalopathy syndrome secondary to hypertensive emergency. PMID:24647142
NSDL National Science Digital Library
2011-01-01
In this cooperative learning activity students conduct an experiment in probability. For this lesson, students work in groups to pull items one at a time from mystery boxes, answering questions, and predicting outcomes for eight different boxes. Throughout this activity students learn to use the terms: possible, event, predict, probability, impossible, unlikely, equally likely, likely, certain, least likely, most likely, and as likely as. This lesson plan includes a data recording sheet and an assessment sheet in PDF format.
Creep of posterior dental composites.
Papadogianis, Y; Boyer, D B; Lakes, R S
1985-01-01
The creep of microspecimens of posterior dental composites was studied using a torsional creep apparatus. Shear stresses were maintained for 3 h and recovery was followed for 50 h. Creep curves were obtained at 21, 37, and 50 degrees C and four torque levels. The effect of conditioning the specimens in water up to 8 weeks was studied. The posterior composites exhibited linear viscoelastic behavior at low deformations. They had higher shear moduli and greater resistance to creep than conventional and microfilled composites. In aging experiments, maximum shear moduli occurred when specimens were 48 h to 1 week old. Subsequent softening was attributed to water absorption. Residual strain was highest when the composites were stressed within 24 h of initiating polymerization. Residual strain was very low in specimens 48 h to 8 weeks of age. PMID:4077874
Distortions of posterior visual space.
Phillips, Flip; Voshell, Martin G
2009-01-01
The study of spatial vision is a long and well traveled road (which, of course, converges to a vanishing point at the horizon). Its various distortions have been widely investigated empirically, and most concentrate, pragmatically, on the space anterior to the observer. The visual world behind the observer has received relatively less attention and it is this perspective the current experiments address. Our results show systematic perceptual distortions in the posterior visual world when viewed statically. Under static viewing conditions, observer's perceptual representation was consistently 'spread' in a hyperbolic fashion. Directions to distant, peripheral locations were consistently overestimated by about 11 degrees from the ground truth and this variability increased as the target was moved toward the center of the observer's back. The perceptual representation of posterior visual space is, no doubt, secondary to the more immediate needs of the anterior visual world. Still, it is important in some domains including certain sports, such as rowing, and in vehicular navigation. PMID:19764306
Aspects concerning posterior urethral valves
M. D. Melekos; H. W. Asbach; S. Giannoulis; P. Perimenis; G. Barbalias
1989-01-01
Twenty-six boys were evaluated and treated for posterior urethral valves. At the time the valves were diagnosed unilateral\\u000a or bilateral vesicoureteral reflux was present in 58% of the ureters and 69% of the children, while dilatation of the upper\\u000a urinary tract was present in 88% and 92%, respectively. There was a variety of symptoms and signs, but the most prominent
Silverman, C.L.; Simpson, J.R.
1982-11-01
Fifty patients with biopsy-proven cerebellar medulloblastoma were retrospectively analyzed for prognostic factors, survival and patterns of failure. Five- and ten-year actuarial survivals for the entire group were 51% and 42%. Survival and local control were significantly better for the 21 patients who received doses greater that 5000 rad to the posterior fossa (85% and 80% respectively) than for the remaining patients (38% and 38%, respectively). Significant prognostic factors included achievement of local control in the posterior fossa (p = .0001) and dose to the posterior fossa (p = .0005). Sex, age, duration of symptoms, extent of surgery and initial T-stage of disease were not significant. Posterior fossa was the predominant site of failure (71% of failures), but 10% of patients failed in the cerebrum and 12% outside the CNS. This experience confirms that survival rates of 70-80% are achievable with current treatment policies but accurate and consistent dose delivery to the posterior fossa is essential.
Silverman, C.L.; Simpson, J.R.
1982-11-01
Fifty patients with biopsy-proven cerebellar medulloblastoma were retrospectively analyzed for prognostic factors, survival and patterns of failure. Five- and ten-year actuarial survivals for the entire group were 51% and 42%. Survival and local control were significantly better for the 21 patients who received doses greater than 5000 rad to the posterior fossa (85% and 80% respectively) than for the remaining patients (38% and 38%, respectively). Significant prognostic factors included achievement of local control in the posterior fossa (p = .0001) and dose to the posterior fossa (p = .0005). Sex, age, duration of symptoms, extent of surgery and initial T-stage of disease were not significant. Posterior fossa was the predominant site of failure (71% of failures), but 10% of patients failed in the cerebrum and 12% outside the CNS. This experience confirms that survival rates of 70-80% are achievable with current treatment policies but accurate and consistent dose delivery to the posterior fossa is essential.
Posterior glenohumeral joint capsule contracture.
Dashottar, Amitabh; Borstad, John
2012-10-01
Glenohumeral joint posterior capsule contracture may cause shoulder pain by altering normal joint mechanics. Contracture is commonly noted in throwing athletes but can also be present in nonthrowers. The cause of contracture in throwing athletes is assumed to be a response to the high amount of repetitive tensile force placed on the tissue, whereas the mechanism of contracture in nonthrowers is unknown. It is likely that mechanical and cellular processes interact to increase the stiffness and decrease the compliance of the capsule, although the exact processes that cause a contracture have not been confirmed. Cadaver models have been used to study the effect of posterior capsule contracture on joint mechanics and demonstrate alterations in range of motion and in humeral head kinematics. Imaging has been used to assess posterior capsule contracture, although standard techniques and quantification methods are lacking. Clinically, contracture manifests as a reduction in glenohumeral internal rotation and/or cross body adduction range of motion. Stretching and manual techniques are used to improve range of motion and often decrease symptoms in painful shoulders. PMID:24265649
The feature-based posterior crown design in a dental CAD\\/CAM system
Ya-Li Song; Jia Li; Ling Yin; Tian Huang; Ping Gao
2007-01-01
This paper presents a newly developed CAD approach for a quick and accurate design of a dental posterior prosthesis. The approach\\u000a arises from the basic idea that every human tooth has its own specific features. Based upon the features of the standard posterior\\u000a tooth, the initial data containing the defined feature points are firstly acquired from the scanned points of
Multiple model cardinalized probability hypothesis density filter
NASA Astrophysics Data System (ADS)
Georgescu, Ramona; Willett, Peter
2011-09-01
The Probability Hypothesis Density (PHD) filter propagates the first-moment approximation to the multi-target Bayesian posterior distribution while the Cardinalized PHD (CPHD) filter propagates both the posterior likelihood of (an unlabeled) target state and the posterior probability mass function of the number of targets. Extensions of the PHD filter to the multiple model (MM) framework have been published and were implemented either with a Sequential Monte Carlo or a Gaussian Mixture approach. In this work, we introduce the multiple model version of the more elaborate CPHD filter. We present the derivation of the prediction and update steps of the MMCPHD particularized for the case of two target motion models and proceed to show that in the case of a single model, the new MMCPHD equations reduce to the original CPHD equations.
Confidence Probability versus Detection Probability
Axelrod, M
2005-08-18
In a discovery sampling activity the auditor seeks to vet an inventory by measuring (or inspecting) a random sample of items from the inventory. When the auditor finds every sample item in compliance, he must then make a confidence statement about the whole inventory. For example, the auditor might say: ''We believe that this inventory of 100 items contains no more than 5 defectives with 95% confidence.'' Note this is a retrospective statement in that it asserts something about the inventory after the sample was selected and measured. Contrast this to the prospective statement: ''We will detect the existence of more than 5 defective items in this inventory with 95% probability.'' The former uses confidence probability while the latter uses detection probability. For a given sample size, the two probabilities need not be equal, indeed they could differ significantly. Both these probabilities critically depend on the auditor's prior belief about the number of defectives in the inventory and how he defines non-compliance. In other words, the answer strongly depends on how the question is framed.
NSDL National Science Digital Library
2013-01-01
This webpage contains probability investigations in the form of word problems. The investigations are located on the left hand side of the page on the navigation bar: the links are "Recommended Investigations" and "Additional Investigations". Within each investigation there are additional links to external resources that can be used to solve or illustrate the problem.
NSDL National Science Digital Library
The Concord Consortium
2011-12-11
The modern view of an atom consists of a nucleus made from protons and neutrons with electrons surrounding it in regions of high probability called orbitals. In this activity, students build computer models of atoms by adding and removing electrons, protons, and neutrons.
NSDL National Science Digital Library
Corey Heitschmidt
2000-01-01
Student will conduct a coin tossing experiment for 30 trials. Their results will be graphed, showing a line graph that progresses toward the theoretical probability. Students will observe that as the number of trials increases they begin to see a graphical representation of the Law of Large Numbers. Instructions, handouts, and a lesson extension are all included here.
Chapman, Teresa; Mahalingam, Sowmya; Ishak, Gisele E; Nixon, Jason N; Siebert, Joseph; Dighe, Manjiri K
2015-01-01
This article is the first portion of a two-part review that illustrates the normal appearance of the cerebellum and posterior fossa on prenatal ultrasound and MRI and on postnatal diagnostic imaging studies. Classification and terminology of posterior fossa abnormalities in the literature are confusing due to evolution of concepts and sometimes lack of consensus. Accurate classification of posterior fossa anomalies is important for predicting fetal outcome and for appropriate counseling. In Part 1 of this review, prenatal and postnatal imaging techniques for assessing the posterior fossa will be discussed, followed by a discussion of how cerebellar malformations may be classified. PMID:25457573
NSDL National Science Digital Library
This collection from the MAA Mathematical Sciences Digital Library brings together probability resources from a wide range of sources. First-time visitors can look through topics such as basic probability, games of chance, various discrete and continuous distributions, and more. As they browse around, visitors will notice that each resource has a title, a format, a rating, and a link to more information. The formats are quite diverse, and include interactive graphics, instructional fact sheets, and so on. All told, there are several hundred resources here that could be used in high school and college mathematics classrooms. Perhaps the most interesting sections here are the Famous Problems, which include the celebrated Monty Hall problem and the "birds on a wire."
Reconstruction of the posterior cruciate ligament with allograft.
Bullis, D W; Paulos, L E
1994-07-01
PCL reconstruction is often a necessary procedure to regain functional knee stability. The procedures used are not able to precisely recreate normal anatomy but are able to provide functional stability to posteriorly destabilized knees when properly performed. Our arthroscopic-assisted procedure limits the soft tissue dissection required and enables the best possible visualization for accurate graft placement. This limits scarring and maximizes the ability of the surgeon to provide posterior knee stability. Allograft tissue, when used as an ACL substitute, was initially believed to be as good as autogenous tissue. It is now believed to be inferior because of slower healing and a tendency to attenuate. PCL allograft reconstructions have not been adequately studied to determine if this same tendency of graft attenuation occurs. In many knees, however, adequate autogenous tissue may not be available, and the only chance to regain stability requires using an allograft. It is in these circumstances that the authors recommend allograft reconstructions. PMID:7954885
Posterior mediastinal hyperfunctioning insular thyroid carcinoma.
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
Non-Gaussian Posteriors arising from Marginal Detections
Bruce A. Bassett; Niayesh Afshordi
2012-03-16
We show that in cases of marginal detections (~ 3\\sigma), such as that of Baryonic Acoustic Oscillations (BAO) in cosmology, the often-used Gaussian approximation to the full likelihood is very poor, especially beyond ~3\\sigma. This can radically alter confidence intervals on parameters and implies that one cannot naively extrapolate 1\\sigma-errorbars to 3\\sigma, and beyond. We propose a simple fitting formula which corrects for this effect in posterior probabilities arising from marginal detections. Alternatively the full likelihood should be used for parameter estimation rather than the Gaussian approximation of a just mean and an error.
Posterior urethral valves and vesicolithiasis in children
E. Neulander; J. Kaneti
1996-01-01
Although posterior urethral valves is a well known and important entity in paediatric urology, its association with bladder\\u000a calculi is not well documented and this condition is not discussed commonly in the literature. Association between posterior\\u000a urethral valves and vesicolithiasis is presented in three children.
Posterior Urethral Valves: Inaccuracy of Prenatal Diagnosis
Jodi F. Abbott; Deborah Levine; Ronald Wapner
1998-01-01
This study was undertaken to determine the specificity of prenatal diagnosis of posterior urethral valves. Twenty-two fetuses were diagnosed in utero with posterior urethral valves due to the presence of persistent megacystis and hydronephrosis. Ten cases had oligohydramnios and 12 had normal or increased fluid. Confirmation of diagnosis was not available in 3 fetuses. Only 8 of 19 fetuses had
Evaluation of the outcomes after posterior urethroplasty
Liberman, Daniel; Pagliara, Travis J.; Pisansky, Andrew; Elliott, Sean P.
2015-01-01
Posterior urethral injury is a clinically significant complication of pelvic fractures. The management is complicated by the associated organ injuries, distortion of the pelvic anatomy and the ensuing fibrosis that occurs with urethral injury. We report a review of the outcomes after posterior urethroplasty in the context of pelvic fracture urethral injury. PMID:26019979
Nonoperatively treated isolated posterior cruciate ligament injuries
Paul M. Keller; K. Donald Shelbourne; John R. McCarroll; Arthur C. Rettig
1993-01-01
To evaluate the theory that isolated posterior cruciate ligament injuries do well when treated nonoperatively, we reviewed 40 patients (mean age, 33 years at fol lowup ; average interval from injury, 6 years) who com pleted a modified Noyes knee questionnaire and were reevaluated by physical examination, radiographs, and isokinetic testing. Thirty of the injuries to the posterior cruciate ligament
Cerebral Palsy Spasticity. Selective Posterior Rhizotomy
Warwick J. Peacock; Leila J. Arens; Barbara Berman
1987-01-01
We have performed selective posterior rhizotomies on 60 children with cerebral palsy. The procedure involves lumbar laminectomy with stimulation of the rootlets (fascicles) of the second lumbar to the first sacral posterior roots bilaterally; those rootlets associated with an abnormal motor response, as evidenced by sustained or diffused muscular contraction, are divided leaving intact rootlets associated with a brief localized
Consistency of Posterior Distributions for Neural Networks
Consistency of Posterior Distributions for Neural Networks Herbert Lee \\Lambda May 21, 1998 Abstract In this paper we show that the posterior distribution for feedforward neural networks is asymp neural networks for nonparametric regression in a Bayesian framework. Keywords: Bayesian statistics
Extraaxial Ependymoma of the Posterior Fossa
Melanie B. Fukui; Jeffery P. Hogg; A. Julio Martinez
Summary: We report an unusual case of an extraaxial ependy- moma of the posterior fossa in an adult. MR imaging showed a heterogeneously enhancing extraaxial mass with a cystic com- ponent. Ependymoma should be included in the differential diag- nosis of uncommon extraaxial masses of the posterior fossa.
Vanessa J. C. Wood; Michelle B. Sabick; Ron P. Pfeiffer; Seth M. Kuhlman; Jason H. Christensen; Michael J. Curtin
2011-01-01
Background: Despite considerable medical advances, arthroscopy remains the only definitive means of superior labrum anterior-posterior (SLAP) lesion diagnosis. Natural shoulder anatomic variants limit the reliability of radiographic findings and clinical evaluations are not consistent. Accurate clinical diagnostic techniques would be advantageous because of the invasiveness, patient risk, and financial cost associated with arthroscopy.Purpose: The purpose of this study was to
Tai-Yuan Chuang; Chih-Hwa Chen; Shih-Wei Chou; Yeung-Jen Chen; Wen-Jer Chen
2004-01-01
Surgical reconstruction of the posterior cruciate ligament (PCL) is indicated in a PCL-deficient knee with symptomatic instability and injury to other ligaments. However, the choice of graft tissues remains controversial. The tibial inlay method has the benefit of preventing the acute turn associated with transtibial reconstruction and permitting accurate anatomic placement of the graft. This study describes an arthroscopic-assisted inlay
Validation of Bayesian posterior distributions using a multidimensional Kolmogorov--Smirnov test
Harrison, Diana; Carvalho, Pedro; Hobson, Michael
2014-01-01
We extend the Kolmogorov--Smirnov (K-S) test to multiple dimensions by suggesting a $\\mathbb{R}^n \\rightarrow [0,1]$ mapping based on the probability content of the highest probability density region of the reference distribution under consideration; this mapping reduces the problem back to the one-dimensional case to which the standard K-S test may be applied. The universal character of this mapping also allows us to introduce a simple, yet general, method for the validation of Bayesian posterior distributions of any dimensionality. This new approach goes beyond validating software implementations; it provides a sensitive test for all assumptions, explicit or implicit, that underlie the inference. In particular, the method assesses whether the inferred posterior distribution is a truthful representation of the actual constraints on the model parameters. We illustrate our multidimensional K-S test by applying it to a simple two-dimensional Gaussian toy problem, and demonstrate our method for posterior validat...
Adaptive approximation of higher order posterior statistics
Lee, Wonjung, E-mail: leew@maths.ox.ac.uk
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.
Bilateral posterior circulation stroke secondary to a crotalid envenomation: case report.
Vale, Thiago Cardoso; Leite, Alysson Ferreira; Hora, Priscila Ribeiro da; Coury, Marayra Inês França; Silva, Ricardo Cipriano da; Teixeira, Antônio Lúcio
2013-01-01
Snake bite envenoming is a disease with potential serious neurological complications. We report a case of an adolescent who was bitten by a rattlesnake and developed bilateral posterior circulation stroke. The rattlesnake was later identified as being Crotalus durissus terrificus. Stroke was probably due to toxic vasculitis or toxin-induced vascular spasm and endothelial damage. PMID:23740059
14 CFR 417.224 - Probability of failure analysis.
Code of Federal Regulations, 2011 CFR
2011-01-01
...probability in a consistent manner. A launch vehicle failure probability estimate must use accurate data, scientific principles, and a method that is statistically or probabilistically valid. For a launch vehicle with fewer than two...
14 CFR 417.224 - Probability of failure analysis.
Code of Federal Regulations, 2014 CFR
2014-01-01
...probability in a consistent manner. A launch vehicle failure probability estimate must use accurate data, scientific principles, and a method that is statistically or probabilistically valid. For a launch vehicle with fewer than two...
14 CFR 417.224 - Probability of failure analysis.
Code of Federal Regulations, 2010 CFR
2010-01-01
...probability in a consistent manner. A launch vehicle failure probability estimate must use accurate data, scientific principles, and a method that is statistically or probabilistically valid. For a launch vehicle with fewer than two...
14 CFR 417.224 - Probability of failure analysis.
Code of Federal Regulations, 2013 CFR
2013-01-01
...probability in a consistent manner. A launch vehicle failure probability estimate must use accurate data, scientific principles, and a method that is statistically or probabilistically valid. For a launch vehicle with fewer than two...
14 CFR 417.224 - Probability of failure analysis.
Code of Federal Regulations, 2012 CFR
2012-01-01
...probability in a consistent manner. A launch vehicle failure probability estimate must use accurate data, scientific principles, and a method that is statistically or probabilistically valid. For a launch vehicle with fewer than two...
POSTERIOR INTEROSSEOUS NERVE SYNDROME DUE TO PSEUDOGOUT
Y. TANIGUCHI; M. YOSHIDA; T. TAMAKI
1999-01-01
Posterior interosseous nerve palsy associated with pseudogout of the elbow joint in a 71-year-old woman is described. Local steroid injection and administration of a nonsteroidal anti-inflammatory drug was effective in treatment.
Posterior Hip Pain in an Athletic Population
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
Posterior odds ratios for selected regression hypotheses
A. Zellner; A. Siow
1980-01-01
Summary Bayesian posterior odds ratios for frequently encountered hypotheses about parameters of the normal linear multiple regression\\u000a model are derived and discussed. For the particular prior distributions utilized, it is found that the posterior odds ratios\\u000a can be well approximated by functions that are monotonic in usual sampling theoryF statistics. Some implications of this finding and the relation of our work
Katsuki, Fumi; Saito, Mizuki; Constantinidis, Christos
2014-09-01
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 and 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. 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 on 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 the 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
Selective posterior decompression of the cervical spine.
Kim, Kyongsong; Isu, Toyohiko; Sugawara, Atsushi; Matsumoto, Ryoji; Isobe, Masanori; Morimoto, Daijiro; Mishina, Masahiro; Kobayashi, Shiro; Yoshida, Daizo; Teramoto, Akira
2011-01-01
Posterior decompression of the cervical spine is an accepted treatment for patients with cervical canal disease, but some patients experience postoperative axial pain and C5 or C6 palsy that affect their quality of life. Here we describe selective posterior decompression using a spinous process-splitting approach to prevent these complications performed in 17 patients with myelopathy treated at median 2.4 levels by selective posterior decompression via the transspinous approach. Clinical symptoms, axial pain, and C5 or C6 palsy were compared before and after treatment. The range of motion of the cervical spine and shift of the cervical cord were studied at the C5 level. All patients experienced symptom improvement and none suffered deterioration or required reoperation. The Japanese Orthopaedic Association score improved from 10.9 to 14.4 points and none of the patients reported C5 or C6 palsy or axial pain at the last follow-up visit. There was no statistically significant change in pre- and postoperative cervical alignment and range of motion. The posterior shift of the spinal cord at the C5 level was 1.7 mm. None of our 17 patients experienced significant postoperative axial pain after selective posterior decompression via the transspinous approach. Minimal spinal cord shift at the C5 level may have contributed to the reduced incidence of postoperative C5 or C6 palsy in our series. Selective posterior decompression is less invasive and effective in some patients with cervical canal disease. PMID:21358151
Accurately modeling the internet topology.
Zhou, Shi; Mondragón, Raúl J
2004-12-01
Based on measurements of the internet topology data, we found that there are two mechanisms which are necessary for the correct modeling of the internet topology at the autonomous systems (AS) level: the interactive growth of new nodes and new internal links, and a nonlinear preferential attachment, where the preference probability is described by a positive-feedback mechanism. Based on the above mechanisms, we introduce the positive-feedback preference (PFP) model which accurately reproduces many topological properties of the AS-level internet, including degree distribution, rich-club connectivity, the maximum degree, shortest path length, short cycles, disassortative mixing, and betweenness centrality. The PFP model is a phenomenological model which provides an insight into the evolutionary dynamics of real complex networks. PMID:15697435
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
Estimating the full posterior pdf with particle filters
NASA Astrophysics Data System (ADS)
Ades, Melanie; van Leeuwen, Peter Jan
2013-04-01
The majority of data assimilation schemes rely on linearity assumptions. However as the resolution and complexity of both the numerical models and observations increases, these linearity assumptions become less appropriate. A need is arising for fully non-linear data assimilation schemes, such as particle filters. Recently, new particle filter schemes have been generated that explore the freedom in proposal densities and that are quite effective in estimating the mean of the posterior probability density function (pdf), even in very high dimensional systems. However, in non-linear data assimilation the solution to the data assimilation problem is the full posterior pdf. At the same time we can only afford a limited number of particles. Here we concentrate on the equivalent weights particle filter in conjunction with a 65,000 dimensional Barotropic Vorticity model. Specifically we test the ability of the scheme to represent the posterior in three important areas. In many actual geophysical applications, observations will be sparse and may well be unevenly distributed. We discuss the effect of changing the frequency, number and distribution of the observed variables on the ensemble representation of the posterior pdf. Specifically we show that the filter has remarkably good convergence in marginal and joint pdfs with ensemble size, and the rank histograms are quite flat, even with low observation numbers and low observation frequencies. Only when the observation frequency is much larger than the typical decorrelation time scale of the system do we see underdispersive ensembles when using 32 particles. The second area attempts to replicate the realistic situation of using a geophysical model designed without a full understanding of the error statistics of the truth. This is done by using deliberately erroneous error statistics in the ensemble equations compared to those used to generate the truth. Specifically we consider changes in the correlation length-scales and variances in the model error statistics. Again the filter is remarkably successful in generating correct posterior pdfs, although rank histograms tend to point to under- or overdispersive ensembles. One of the interesting results is that when we overestimate the model error amplitude the ensemble is underdispersive. We present an explanation for this counter-intuitive phenomenon. Finally we show that the computational effort involved in the equivalent-weights particle filter is comparable to running a simple resampling particle filter with the same number of particles.
Posterior urethral polyp with type I posterior urethral valves: a rare association in a neonate.
Kesan, Krushnakumar V; Gupta, Rahul Kumar; Kothari, Paras; Gupta, Abhaya; Mudkhedkar, Kedar; Kamble, Ravikiran; Dikshit, K Vishesh
2014-06-01
Urethral polyp is a rare cause of bladder outlet obstruction, voiding dysfunction, and hematuria in the pediatric age group. Urethral polyps are rarely associated with other congenital urinary tract anomalies. In this study, we report a case of solitary posterior urethral polyp with type I posterior urethral valve in a 7-day-old neonate presented with urinary retention and deranged renal function. The polyp was diagnosed on cystoscopy. Transurethral resection of the polyp with posterior urethral valve fulguration was performed. Pathologic assessment revealed a fibroepithelial lesion, which was consistent with congenital posterior urethral polyp. PMID:24767515
Accurate atomic data for industrial plasma applications
Griesmann, U.; Bridges, J.M.; Roberts, J.R.; Wiese, W.L.; Fuhr, J.R. [National Inst. of Standards and Technology, Gaithersburg, MD (United States)
1997-12-31
Reliable branching fraction, transition probability and transition wavelength data for radiative dipole transitions of atoms and ions in plasma are important in many industrial applications. Optical plasma diagnostics and modeling of the radiation transport in electrical discharge plasmas (e.g. in electrical lighting) depend on accurate basic atomic data. NIST has an ongoing experimental research program to provide accurate atomic data for radiative transitions. The new NIST UV-vis-IR high resolution Fourier transform spectrometer has become an excellent tool for accurate and efficient measurements of numerous transition wavelengths and branching fractions in a wide wavelength range. Recently, the authors have also begun to employ photon counting techniques for very accurate measurements of branching fractions of weaker spectral lines with the intent to improve the overall accuracy for experimental branching fractions to better than 5%. They have now completed their studies of transition probabilities of Ne I and Ne II. The results agree well with recent calculations and for the first time provide reliable transition probabilities for many weak intercombination lines.
A highly accurate interatomic potential for argon
NASA Astrophysics Data System (ADS)
Aziz, Ronald A.
1993-09-01
A modified potential based on the individually damped model of Douketis, Scoles, Marchetti, Zen, and Thakkar [J. Chem. Phys. 76, 3057 (1982)] is presented which fits, within experimental error, the accurate ultraviolet (UV) vibration-rotation spectrum of argon determined by UV laser absorption spectroscopy by Herman, LaRocque, and Stoicheff [J. Chem. Phys. 89, 4535 (1988)]. Other literature potentials fail to do so. The potential also is shown to predict a large number of other properties and is probably the most accurate characterization of the argon interaction constructed to date.
Steven M. Schimmel; Martin F. Müller; Norbert Dillier
2009-01-01
We present a new ldquoshoeboxrdquo room acoustics simulator that is designed to support research into signal processing algorithms that are robust to reverberation. It is an improvement over existing room acoustics simulators because it is computationally fast, portable to many kinds of research environments, and flexible to use. The proposed simulator is also perceptually accurate because it models both specular
Posterior urethral disruption secondary to a penetrating gluteal injury
Ronen Rub; Ralph Madeb; Yoram Kluger; Tzipi Chen; Yoav Avidor
2000-01-01
We report a case of a complete posterior urethral injury secondary to a penetrating gluteal injury. Posterior urethral injury usually occurs in male patients with pelvic trauma. The reported incidence of urethral injury with pelvic fracture ranges from 1.6% to 25% (mean 10%), with 66% of them being complete posterior urethral ruptures. Causes of posterior urethral disruptions include blunt trauma,
Posterior Predictive Bayesian Phylogenetic Model Selection
Lewis, Paul O.; Xie, Wangang; Chen, Ming-Hui; Fan, Yu; Kuo, Lynn
2014-01-01
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. [Bayesian; conditional predictive ordinate; CPO; L-measure; LPML; model selection; phylogenetics; posterior predictive.] PMID:24193892
Conditional Probability and Probability of Simultaneous Events
NSDL National Science Digital Library
2010-01-01
This lesson is designed to further students' practice with probability as well as introduce them to conditional probability and probabilities of simultaneous independent events. The lesson provides links to discussions and activities related to conditional and simultaneous probabilities as well as suggested ways to integrate them into the lesson. Finally, this lesson provides links to follow-up lessons designed for use in succession with this one.
Melinda J. Cromie; Robert A. Siston; Nicholas J. Giori; Scott L. Delp
2008-01-01
Abnormal anterior translation of the femur on the tibia has been observed in mid flexion (20-608) following posterior stabilized total knee arthroplasty. The underlying biomechanical causes of this abnormal motion remain unknown. The purpose of this study was to isolate the effects of posterior cruciate ligament removal on knee motion after total knee arthroplasty. We posed two questions: Does removing
The clinical anatomy of the posterior gastric artery revisited.
Loukas, Marios; Wartmann, Christopher T; Louis, Robert G; Tubbs, R Shane; Ona, Mel; Curry, Brian; Jordan, Robert; Colborn, Gene L
2007-07-01
A consensus concerning the incidence, course and distribution of the posterior gastric artery (PGA) has yet to be reached. Recent literature has explored and subsequently demonstrated the importance of the identification of this vessel in surgical procedures such as subtotal gastrectomy, splenectomy and pancreatic transplantation. The gross anatomy of the PGA was examined in 120 adult human cadavers. The PGA was identified as that artery which provided the predominant arterial supply to the posterior wall of the superior portion of the gastric body near the cardiac region and fundus. A PGA was identified in 81.6% of specimens. The most common origin of the PGA was from the left gastric artery (type I), occurring in 41.8% of specimens. In decreasing order of prevalence, were origins from the splenic artery (Type II), occurring in 25.5%; from both the left gastric and splenic arteries as double PGAs (Type III) in 22.4%; and from the celiac trunk (Type IV) occurring in 10.2%. The importance of accurate delineation of the PGA is crucial for pancreatic transplantation and gastric tumor removal. In addition, knowledge of variations in this vessel's origin could prove useful in transcatheter arterial embolization for the treatment of chronic bleeding from gastric ulcers. Furthermore, ligation of this vessel during partial gastrectomy, pancreaticoduodenectomy, and parietal cell vagotomy may result in gastric wall necrosis and gastric stump leak. PMID:17563830
Clinical evaluation of posterior canal benign paroxysmal positional vertigo
Ibekwe, Titus S.; Rogers, C.
2012-01-01
Background: Benign paroxysmal positional vertigo (BPPV) is a mechanical peripheral vestibular disorder which may involve any of the three semicircular canals but principally the posterior. In as much as the literature has described theories to explain the mechanism of BPPV and also contains scholarly works that elucidate BPPV; its management remains an enigma to most clinicians. To this end, this work was aimed at outlining an evidence-based best practice for most common form of BPPV. Materials and Methods: A systematic review of the literature was conducted between 1948 and June 2011 in PubMed, Embase, Ovid, and Cochrane database through the online Library of the University of Cape Town. Seventy-nine worthy articles that addressed the study were selected on consensus of the two authors. Conclusion: There is consensus for the use of canalith repositioning procedures as the best form of treatment for posterior canal canalolithiasis. However, successful treatment is dependent on accurate identification of the implicated canal and the form of lithiasis. Furthermore, clinicians should note that there is no place for pharmacological treatment of BPPV; unless it is to facilitate repositioning. PMID:23271854
Late presentation of posterior urethral valves.
Jalbani, Imran Khan; Biyabani, Syed Raziuddin
2014-05-01
Presence of posterior urethral valves (PUV) is the most common cause of urinary tract obstruction in the male neonate. Late presentation occurs in 10% of cases. We present a case of PUVs in an adult male who presented with history of obstructive lower urinary tract symptoms and hematuria. On evaluation, he was found to have raised serum creatinine level. A voiding cystourethrogram (VCUG) could not be completely performed because of narrowing in the posterior urethra. A rigid urethrocystoscopy was performed at which he was found to have type-I posterior urethral valve which were fulgurated. A repeat uroflowmetry revealed maximum flow rate of 12 ml/second. This case highlights that PUVs is not solely a disease of infancy but may also present late. VCUG is the radiological investigation of choice but the diagnosis may be missed. A urethrocystoscopy is advised if there is a high index of suspicion. PMID:24906275
NSDL National Science Digital Library
Jeanine Pearce
2009-01-01
In this probability unit plan, three lessons guide students through the use of probability vocabulary, displaying probability on a number line, writing probability as a fraction, and making predictions based on probability. The unit begins with students learning and applying new vocabulary to the book "Probably Pistachio" by Stuart J. Murphy. In lesson two students use dice, spinners, and real life events to write probability as fractions and make predictions based on these fractions, while still using the probability vocabulary. The third lesson includes another probability experiment and a summative assessment. All student worksheet are included with answer keys in PDF format.
Posterior predictive checking of multiple imputation models.
Nguyen, Cattram D; Lee, Katherine J; Carlin, John B
2015-07-01
Multiple imputation is gaining popularity as a strategy for handling missing data, but there is a scarcity of tools for checking imputation models, a critical step in model fitting. Posterior predictive checking (PPC) has been recommended as an imputation diagnostic. PPC involves simulating "replicated" data from the posterior predictive distribution of the model under scrutiny. Model fit is assessed by examining whether the analysis from the observed data appears typical of results obtained from the replicates produced by the model. A proposed diagnostic measure is the posterior predictive "p-value", an extreme value of which (i.e., a value close to 0 or 1) suggests a misfit between the model and the data. The aim of this study was to evaluate the performance of the posterior predictive p-value as an imputation diagnostic. Using simulation methods, we deliberately misspecified imputation models to determine whether posterior predictive p-values were effective in identifying these problems. When estimating the regression parameter of interest, we found that more extreme p-values were associated with poorer imputation model performance, although the results highlighted that traditional thresholds for classical p-values do not apply in this context. A shortcoming of the PPC method was its reduced ability to detect misspecified models with increasing amounts of missing data. Despite the limitations of posterior predictive p-values, they appear to have a valuable place in the imputer's toolkit. In addition to automated checking using p-values, we recommend imputers perform graphical checks and examine other summaries of the test quantity distribution. PMID:25939490
NSDL National Science Digital Library
2004-10-15
This set of probability lesson plans includes a variety of activities that engage students and reinforce the concepts of probability. Through these lessons students play a traditional Native American Stick game, they read Probably Pistachio, by Stuart J. Murphy, and they demonstrate probability with probability bags and dice. Included in this resource is teacher background information, student worksheets (pdf), and extension suggestions.
Lee, Dong Yeong; Kim, Dong Hee; Park, Jin Sung; Nam, Dae Cheol; Cho, Seong Hee; Jeong, Jin Hoon
2014-01-01
Recently, several new techniques for anatomic posterior cruciate ligament reconstruction (PCLR) have emerged and are believed to restore the normal anatomy of the posterior cruciate ligament more accurately. Despite the latest trend, the optimal methods for anatomic PCLR remain controversial. The purpose of this research is to review surgical techniques for PCLR in cadaver studies and suggest consistent and reproducible technical criteria. For the review of the literature, MEDLINE and EMBASE were screened for articles on anatomic PCLR. Only basic science studies on PCLR performed on human cadavers and written in English were included. Seventeen studies were included in this systematic review. Only the tunnel positions, graft types, and surgical techniques were reported in the majority of the studies. There were many variations of the reported tunnel positions, graft types, and surgical techniques among the studies. In most studies, surgical techniques for consistent and reproducible anatomic PCLR were not explained clearly. Therefore, high level medical research should be encouraged in order to establish standard surgical techniques for anatomic PCLR. PMID:25505700
Imaging the posterior mediastinum: a multimodality approach
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
Structure of the human tibialis posterior tendon
Wolf Petersen; Gerrit Hohmann; Thomas Pufe; Michael Tsokos; Thore Zantop; Friedrich Paulsen; Bernhard Tillmann
2004-01-01
Background The most common site of rupture of the posterior tibial tendon is the retromalleolar region where the tendon changes its direction\\u000a of pull. The aim of this study was to characterize the tissue of the gliding zone of the tibialis posterior tendon to gain\\u000a further knowledge about possible structural causes for spontaneous tendon rupture.\\u000a \\u000a \\u000a \\u000a Methods Light microscopy, transmission electron microscopy and
Identification of Bayesian posteriors for coefficients of chaos expansions
Arnst, M. [210 KAP Hall, University of Southern California, Los Angeles, CA 90089 (United States)], E-mail: arnst@usc.edu; Ghanem, R. [210 KAP Hall, University of Southern California, Los Angeles, CA 90089 (United States); Soize, C. [Universite Paris-Est, Laboratoire de Modelisation et Simulation Multi-Echelle, MSME UMR8208 CNRS, 5 bd Descartes, Champs-sur-Marne, 77454 Marne-la-Vallee, Cedex 2 (France)
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.
Arbitrarily accurate narrowband composite pulse sequences
NASA Astrophysics Data System (ADS)
Vitanov, Nikolay V.
2011-12-01
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 sin2N(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 ?.
Random Variables Probability Distribution
Bardsley, John
Random Variables Probability Distribution Expected Value and Variance The Binomial Distribution Stat 491: Biostatistics Chapter 4: Discrete Probability Distributions Solomon W. Harrar The University of Montana Fall 2012 Chapter 4: Discrete Probability Distributions Stat 491: Biostatistics #12;Random
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.
Posterior predictive Bayesian phylogenetic model selection.
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
Genitourinary neurofibromatosis mimicking posterior urethral valves
James A. Brown; Jay B. Levy; Stephen A. Kramer
1997-01-01
A 12-year-old boy, examined after an episode of acute urinary retention, was found to have neurofibromatosis of the bladder neck and prostatic urethra. His symptoms of bladder outlet obstruction and radiographic findings of a dilated prostatic urethra mimicked posterior urethral valves. Complete urologic investigation, including cystourethroscopy, revealed that the dilatation of the prostatic urethra was secondary to neural involvement of
Markov Chains for Exploring Posterior Distributions
Luke Tierney
1994-01-01
Several Markov chain methods are available for sampling from a posterior distribution. Two important examples are the Gibbs sampler and the Metropolis algorithm. In addition, several strategies are available for constructing hybrid algorithms. This paper outlines some of the basic methods and strategies and discusses some related theoretical and practical issues. On the theoretical side, results from the theory of
Arthroscopic reconstruction of the posterior cruciate ligament
Chih-Hwa Chen; Wen-Jer Chen; Chun-Hsiung Shih
2002-01-01
Purpose: Considerable controversies remain on the graft choice and fixation methods in the posterior cruciate ligament (PCL) reconstruction. The purpose of this study was to compare, at minimal 2-year follow-up, the outcomes of PCL reconstruction between using quadriceps tendon autograft and using quadruple hamstring tendon autograft. Type of Study: Case series. Methods: All patients received only PCL reconstruction without combined
BAER suppression during posterior fossa dural opening
Shields, Christopher B.; Shields, Lisa B. E.; Jiang, Yi Dan; Yao, Tom; Zhang, Yi Ping; Sun, David A.
2015-01-01
Background: Intraoperative monitoring with brainstem auditory evoked responses (BAER) provides an early warning signal of potential neurological injury and may avert tissue damage to the auditory pathway or brainstem. Unexplained loss of the BAER signal in the operating room may present a dilemma to the neurosurgeon. Methods: This paper documents two patients who displayed a unique mechanism of suppression of the BAER apparent within minutes following dural opening for resection of a posterior fossa meningioma. Results: In two patients with anterior cerebellopontine angle and clival meningiomas, there was a significant deterioration of the BAER soon after durotomy but prior to cerebellar retraction and tumor removal. Intracranial structures in the posterior fossa lying between the tumor and dural opening were shifted posteriorly after durotomy. Conclusion: We hypothesized that the cochlear nerve and vessels entering the acoustic meatus were compressed or stretched when subjected to tissue shift. This movement caused cochlear nerve dysfunction that resulted in BAER suppression. BAER was partially restored after the tumor was decompressed, dura repaired, and bone replaced. BAER was not suppressed following durotomy for removal of a meningioma lying posterior to the cochlear complex. Insight into the mechanisms of durotomy-induced BAER inhibition would allay the neurosurgeon's anxiety during the operation. PMID:25883849
Chemotherapy of Pediatric Posterior Fossa Tumors
Michael S. Edwards; Victor A. Levin; Charles B. Wilson
1980-01-01
Results of chemotherapy of recurrent posterior fossa tumors in children are presented. Cerebellar astrocytoma, ependymoma, and brain stem glioma have all shown objectively determined responses to treatment with nitrosourea compounds (BCNU or CCNU). Medulloblastoma has shown objectively determined response to various chemotherapeutic agents; but in our experience the best responses have been obtained with a combination of a nitrosourea (CCNU),
Posterior Fossa Lateral Ependymoma in Childhood
Mahmoud G. Nagib; Therese O’Fallon
1996-01-01
Over a period extending from 1984 to 1993, 16 children ranging in ages from 2 months to 12 years with posterior fossa ependymoma were treated. Four of these tumors were classified as lateral ependymomas because of their configuration and suspected site of origin. These 4 patients’ ages ranged from
Posterior cranial fossa tumours in childhood
T. Chang; M. M. H. Teng; J. F. Lirng
1993-01-01
We reviewed clinical and CT findings in 133 posterior cranial fossa tumours in children. All had histological diagnosis, apart from 20 cases of brain stem glioma. The majority were intra-axial tumours, including 53 medulloblastomas (40%), 31 cerebellar astrocytomas (23%), 28 brain stem gliomas (21%), 14 ependymomas (11%), and single cases of ganglioglioma, haemangioblastoma and teratoma. Extra-axial tumours formed only 3%,
Neural Network Classifiers Estimate Bayesian a posteriori Probabilities
Michael D. Richard; Richard P. Lippmann
1991-01-01
Many neural network classifiers provide outputs which estimate Bayesian a posteriori probabilities. When the estimation is accurate, network outputs can be treated as probabilities and sum to one. Simple proofs show that Bayesian probabilities are estimated when desired network outputs are 1 of M (one output unity, all others zero) and a squared-error or cross-entropy cost function is used. Results
Grossbach, Andrew J; Abel, Taylor J; Hodis, Brendan; Wassef, Shafik N; Greenlee, Jeremy D W
2014-02-01
Posterior reversible encephalopathy syndrome (PRES) is a well characterized entity resulting from the inability of cerebral autoregulation to adequately protect the brain from uncontrolled hypertension. It primarily affects the occipital lobes, but can also involve the structures in the posterior fossa including the brainstem and cerebellum. Treatment usually consists of strict blood pressure control, but more aggressive management may be indicated with acutely worsening neurological status. We present a patient with hypertensive encephalopathy that resulted in hydrocephalus and brainstem compression necessitating surgical decompression requiring ventriculostomy and suboccipital craniectomy. In rare cases, PRES can present with severe brainstem compression requiring emergent posterior fossa decompression. When brainstem signs are present on exam, emergent posterior fossa decompression may be safer than ventriculostomy alone. PMID:24126039
Late-onset Alzheimer disease genetic variants in posterior cortical atrophy and posterior AD
Carrasquillo, Minerva M.; Khan, Qurat ul Ain; Murray, Melissa E.; Krishnan, Siddharth; Aakre, Jeremiah; Pankratz, V. Shane; Nguyen, Thuy; Ma, Li; Bisceglio, Gina; Petersen, Ronald C.; Younkin, Steven G.; Dickson, Dennis W.; Boeve, Bradley F.; Graff-Radford, Neill R.
2014-01-01
Objective: To investigate association of genetic risk factors for late-onset Alzheimer disease (LOAD) with risk of posterior cortical atrophy (PCA), a syndrome of visual impairment with predominant Alzheimer disease (AD) pathology in posterior cortical regions, and with risk of “posterior AD” neuropathology. Methods: We assessed 81 participants with PCA diagnosed clinically and 54 with neuropathologic diagnosis of posterior AD vs 2,523 controls for association with 11 significant single nucleotide polymorphisms (SNPs) from published LOAD risk genome-wide association studies. Results: There was highly significant association with APOE ?4 and increased risk of PCA (p = 0.0003, odds ratio [OR] = 3.17) and posterior AD (p = 1.11 × 10?17, OR = 6.43). No other locus was significant after corrections for multiple testing, although rs11136000 near CLU (p = 0.019, OR = 0.60) and rs744373 near BIN1 (p = 0.025, OR = 1. 63) associated nominally significantly with posterior AD, and rs3851179 at the PICALM locus had significant association with PCA (p = 0.0003, OR = 2.84). ABCA7 locus SNP rs3764650, which was also tested under the recessive model because of Hardy-Weinberg disequilibrium, also had nominally significant association with PCA risk. The direction of association at APOE, CLU, and BIN1 loci was the same for participants with PCA and posterior AD. The effects for all SNPs, except rs3851179, were consistent with those for LOAD risk. Conclusions: We identified a significant effect for APOE and nominate CLU, BIN1, and ABCA7 as additional risk loci for PCA and posterior AD. Our findings suggest that at least some of the genetic risk factors for LOAD are shared with these atypical conditions and provide effect-size estimates for their future genetic studies. PMID:24670887
NASA Astrophysics Data System (ADS)
Fri?, Roman; Pap?o, Martin
2015-01-01
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.
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
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
Consistency of posterior distributions for neural networks.
Lee, H K
2000-07-01
In this paper we show that the posterior distribution for feedforward neural networks is asymptotically consistent. This paper extends earlier results on universal approximation properties of neural networks to the Bayesian setting. The proof of consistency embeds the problem in a density estimation problem, then uses bounds on the bracketing entropy to show that the posterior is consistent over Hellinger neighborhoods. It then relates this result back to the regression setting. We show consistency in both the setting of the number of hidden nodes growing with the sample size, and in the case where the number of hidden nodes is treated as a parameter. Thus we provide a theoretical justification for using neural networks for nonparametric regression in a Bayesian framework. PMID:10987516
Pseudoexfoliation material on posterior chamber intraocular lenses
da Rocha-Bastos, Ricardo António; Silva, Sérgio Estrela; Prézia, Flávio; Falcão-Reis, Fernando; Melo, António B
2014-01-01
The presence of pseudoexfoliation material on the surface of an intraocular lens (IOL) is a rare finding. We report a series of seven cases with different patterns of pseudoexfoliation material deposition on the posterior chamber IOLs, recognized 2–20 years after cataract surgery. Six patients had an IOL implanted in the capsular bag and one in the ciliary sulcus. Two patients had undergone posterior capsulotomy. Although the pathophysiological mechanisms and clinical significance of this finding remain unknown, the careful follow-up of pseudophakic patients with known or suspected pseudoexfoliation syndrome is essential to monitor the development or progression of glaucoma, since deposition of pseudoexfoliation material continues even after cataract surgery. PMID:25143707
Treatment of posterior fossa tumors in children.
Muzumdar, Dattatraya; Ventureyra, Enrique C G
2010-04-01
The most common posterior fossa tumors in children are medulloblastoma, astrocytoma and ependymoma. Atypical rhabdoid teratoid tumors and brain stem gliomas are relatively rare. As the posterior fossa is a limited space, the tumors presenting in this region cause symptoms early on and require prompt treatment to avoid potential morbidity and mortality. Early detection and diagnosis of these tumors and prompt neurosurgical consultation is crucial in the optimum management of pediatric infratentorial brain tumors. Surgery is the mainstay of treatment, as it provides biopsy and decompression of the tumor. Adjuvant therapy is required in the majority of cases. Recent advances in the field of radiation biology and pharmacology have improved dose and delivery techniques of chemoradiation therapy. In the current era, advances in translational research and molecular genetics have assumed a major role in the pursuit of achieving a 'cure' for these potentially malignant tumors. PMID:20367206
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.
Posterior urethral valve: delayed presentation in adolescence.
Mahadik, Punit; Vaddi, Surya Prakash; Godala, Chandra-Mohan; Sambar, Venkatkrishna; Kulkarni, Sushanth; Gundala, Ramesh
2012-09-01
Posterior urethral valves (PUV) are now commonly suspected on antenatal ultrasound, but can present with a broad spectrum of severity postnatally. Rarely, the diagnosis is missed until adolescence or adulthood when the patient usually presents with lower urinary tract symptoms. We describe an even rarer case of PUV in a late adolescent who first presented with preserved renal function and urinary incontinence. We review the literature on presentation, natural history and outcomes of both early and late presenting PUV cases. PMID:23094222
Posterior urethral valves: Pre and postnatal management
John M. Gatti; Andrew J. Kirsch
2001-01-01
Posterior urethral valves are a common problem encountered by pediatric urologists. The diagnosis is most frequently suggested\\u000a by antenatal screening ultra-sound. A variety of pre- and postnatal parameters have been identified to aid in predicting ultimate\\u000a renal outcome. These prognostic tools are invaluable to the clinician for counseling parents and for choosing appropriate\\u000a manage-ment. Several approaches to the treatment of
Posterior urethral valves: long-term outcome
Paolo Caione; Simona Gerocarni Nappo
Posterior urethral valves represent the most common cause of bladder outlet obstruction in infancy that impairs renal and\\u000a bladder function. Long-term outcome of patients with previous PUV is evaluated. Patients over 18 years of age, treated from\\u000a 1982 to 1995 before the age of 3 years were considered. Previous surgery, renal function, bladder activity, urinary incontinence,\\u000a and fertility\\/sexual activity were evaluated. Clinical
The mechanism of continence after posterior urethroplasty
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
Posterior fossa lesions in childhood and infancy
Irith Reider-Groswasser; Amiram Catz; Shaul Harel
1987-01-01
Forty-three children with CT studies demonstrating abnormalities in the posterior fossa are presented. Tumors constitute the largest group of lesions (53.5%). Their mean size at time of diagnosis was 39.5 mm. Astrocytomas, medulloblastomas, and ependymomas were the most frequent tumors and their CT features are described and discussed. The congenital group of lesions comprised 18.6% of the cases — the
Posterior Urethral Valve: Delayed Presentation in Adolescence
Vaddi, Surya Prakash; Godala, Chandra-Mohan; Sambar, Venkatkrishna; Kulkarni, Sushanth; Gundala, Ramesh
2012-01-01
Posterior urethral valves (PUV) are now commonly suspected on antenatal ultrasound, but can present with a broad spectrum of severity postnatally. Rarely, the diagnosis is missed until adolescence or adulthood when the patient usually presents with lower urinary tract symptoms. We describe an even rarer case of PUV in a late adolescent who first presented with preserved renal function and urinary incontinence. We review the literature on presentation, natural history and outcomes of both early and late presenting PUV cases. PMID:23094222
Imaging Correlates of Posterior Cortical Atrophy
Whitwell, Jennifer L.; Jack, Clifford R.; Kantarci, Kejal; Weigand, Stephen D.; Boeve, Bradley F.; Knopman, David S.; Drubach, Daniel A.; Tang-Wai, David F.; Petersen, Ronald C.; Josephs, Keith A.
2009-01-01
The aim of this study was to compare patterns of cerebral atrophy on MRI, and neurochemistry on magnetic resonance spectroscopy (MRS), in subjects with posterior cortical atrophy (PCA) and typical Alzheimer's disease (AD). Voxel-based morphometry was used to assess grey matter atrophy in 38 subjects with PCA, 38 subjects with typical AD, and 38 controls. Clinical data was assessed in all PCA subjects. Single-voxel 1H MRS located in the posterior cingulate was analyzed in a subset of subjects with PCA, typical AD, and control subjects. PCA showed a pattern of atrophy affecting occipital, parietal and posterior temporal lobes, compared to controls. The pattern was bilateral, but more severe on the right. Subjects with PCA showed greater atrophy in the right visual association cortex than subjects with typical AD, whereas those with AD showed greater atrophy in the left hippocampus than those with PCA. 1H MRS suggested loss of neuronal integrity and glial activation in subjects with PCA and AD. The differing patterns of atrophy on MRI suggest that PCA should be considered a distinct entity from typical AD. PMID:16797786
Probability Bracket Notation and Probability Modeling
Wang, Xing M
2009-01-01
Inspired by the Dirac notation, a new set of symbols, the Probability Bracket Notation (PBN) is proposed for probability modeling. By applying PBN to discrete and continuous random variables, we show that PBN could play a similar role in probability spaces as the Dirac notation in Hilbert vector spaces. The time evolution of homogeneous Markov chains with discrete-time and continuous-time are discussed in PBN. Our system state p-kets are identified with the probability vectors, while our system state p-bra can be identified with the Doi state function or the Peliti standard bra. We also suggest that, by transforming from the Schrodinger picture to the Heisenberg picture, the time-dependence of a system p-ket of a homogeneous MC can be shifted to the observable as a stochastic process.
Probability Bracket Notation and Probability Modeling
Xing M. Wang
2009-09-07
Inspired by the Dirac notation, a new set of symbols, the Probability Bracket Notation (PBN) is proposed for probability modeling. By applying PBN to discrete and continuous random variables, we show that PBN could play a similar role in probability spaces as the Dirac notation in Hilbert vector spaces. The time evolution of homogeneous Markov chains with discrete-time and continuous-time are discussed in PBN. Our system state p-kets are identified with the probability vectors, while our system state p-bra can be identified with the Doi state function or the Peliti standard bra. We also suggest that, by transforming from the Schrodinger picture to the Heisenberg picture, the time-dependence of a system p-ket of a homogeneous MC can be shifted to the observable as a stochastic process.
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
Loukas, Marios; Louis, Robert G; Wartmann, Christopher T; Tubbs, R Shane; Gupta, Ankmalika A; Apaydin, Nihal; Jordan, Robert
2008-03-01
In classical anatomy textbooks the serratus posterior superior muscle was said to elevate the superior four ribs, thus increasing the AP diameter of the thorax and raising the sternum. However, electromyographic and other studies do not support its role in respiration. In order to help resolve this controversy and provide some insight into their possible functionality, the present study aimed at examining the morphology, topography and morphometry of serratus posterior superior and inferior muscles in both normal specimens and those derived from patients with a history of chronic obstructive pulmonary disorder (COPD). These muscles were examined in 50 human cadavers with an age range of 58-82 years. In 18 of the cadavers their histories revealed that they were suffering from COPD. There was no significant difference between right and left sides, race, gender and age and positive COPD history in regard to dimensions and nerves supply of serratus posterior superior and inferior muscles (P > 0.05). Based upon our findings that no morphometric differences exist between the of serratus posterior superior and inferior muscles of COPD patients versus controls, we are suggesting that no respiratory function be attributed to either of the serratus posterior superior and inferior muscles. PMID:18196199
BIODEGRADATION PROBABILITY PROGRAM (BIODEG)
The Biodegradation Probability Program (BIODEG) calculates the probability that a chemical under aerobic conditions with mixed cultures of microorganisms will biodegrade rapidly or slowly. It uses fragment constants developed using multiple linear and non-linear regressions and d...
Quantum Computation Based Probability Density Function Estimation
Ferenc Balázs; Sándor Imre
2004-01-01
Signal processing techniques will lean on blind methods in the near future, where no redundant, resource allocating information will be transmitted through the channel. To achieve a proper decision, however, it is essential to know at least the probability density function (pdf), which to estimate is classically a time consumption and\\/or less accurate hard task, that may make decisions to
NSDL National Science Digital Library
Steven Blumsack
2012-09-14
This resource is designed to introduce students to the concept of probability: the probability of a rare event is represented by a positive number close to zero, the probability of a nearly certain event occurring is represented by a positive number slightly less than one. Students will indicate the approximate probability of events on a number line and determine which events are more likely than others.
Usman Roshan; Satish Chikkagoudar; Dennis R. Livesay
2008-01-01
BACKGROUND: Identification of RNA homologs within genomic stretches is difficult when pairwise sequence identity is low or unalignable flanking residues are present. In both cases structure-sequence or profile\\/family-sequence alignment programs become difficult to apply because of unreliable RNA structures or family alignments. As such, local sequence-sequence alignment programs are frequently used instead. We have recently demonstrated that maximal expected accuracy
Pokta, Suriani
2004-11-15
(s,t), and the vector v corresponds to the function fv(t), then the vector Av corresponds to fAv(s) = n Z 1 0 a(s,t)fv(t)dt and the matrix AB corresponds to the function n Z 1 0 a(s,tau)b(tau,t)dtau. As before this interpretation makes it possible to identify the limit... have ?? ??(B -sigma2I 1 + rho 1 -rho In)v ?? ?? 0 we have B-1 = sigma-2I 1 -rho1 + rho In(1 + O(1/n)). (4.8) When considering Itheta...
A model for equine breed identification using microsatellites and posterior probability testing
Chastain, Pepper Alise
1996-01-01
. Polymerase chain reaction (PCR) assays were performed on DNA from three breed groups of unrelated horses (E. caballus) and from an Arabian half-sib family. PCR amplification was also attempted for homologous loci in Grant's zebra, E. burchelli granti. PCR...
Knowledge, probability, and adversaries
Joseph Y. Halpern; Mark R. Tuttle
1993-01-01
What should it mean for an agent to know or believe an assertion is true with probability 9.99? Different papers [2, 6, 15] give different answers, choosing to use quite different probability spaces when computing the probability that an agent assigns to an event. We show that each choice can be understood in terms of a betting game. This betting
NSDL National Science Digital Library
Ms. Taylor
2009-05-03
Probability is fun! First, guess the magicians number in Magician Probability! Next, answer the questions on 'which is more likely" in the game Probability comparisons. Then, Help sort our Earth in the sorting game. All you have to do is pick up the trash and sort it into the correct pile. Finally, try pumpkin sorting. Just drag the pumpkins into a sorting ...
Peter Cheeseman
1985-01-01
In this paper, it is argued that probability theory, when used correctly, is sufficient for the task of reasoning under un- certainty. Since numerous authors have rejected probability as inadequate for various reasons, the bulk of the paper is aimed at refuting these claims and indicating the sources of error. In particular, the definition of probability as a mea- sure
John L. Pollock
1983-01-01
Probability is sometimes regarded as a universal panacea for epistemology. It has been supposed that the rationality of belief is almost entirely a matter of probabilities. Unfortunately, those philosophers who have thought about this most extensively have tended to be probability theorists first, and epistemologists only secondarily. In my estimation, this has tended to make them insensitive to the complexities
Crouch, Dustin L.; Plate, Johannes F.; Li, Zhongyu; Saul, Katherine R.
2013-01-01
Purpose To determine if transfer to only the anterior branch of the axillary nerve will restore useful function following axillary nerve injury with persistent posterior deltoid and teres minor paralysis. Methods We used a computational musculoskeletal model of the upper limb to determine the relative contributions of posterior deltoid and teres minor to maximum joint moment generated during a simulated static strength assessment and to joint moments during 3 sub-maximal shoulder movements. Movement simulations were performed with and without simulated posterior deltoid and teres minor paralysis to identify muscles which may compensate for their paralysis. Results In the unimpaired limb model, teres minor and posterior deltoid accounted for 16% and 14% of the total isometric shoulder extension and external rotation joint moments, respectively. During the 3 movement simulations, posterior deltoid produced as much as 20% of the mean shoulder extension moment, while teres minor accounted for less than 5% of the mean joint moment in all directions of movement. When posterior deltoid and teres minor were paralyzed, the mean extension moments generated by the supraspinatus, long head of triceps, latissimus dorsi, and middle deltoid increased to compensate. Compensatory muscles were not fully activated during movement simulations when posterior deltoid and teres minor were paralyzed. Conclusions Reconstruction of the anterior branch of the axillary nerve only is an appropriate technique for restoring shoulder abduction strength following isolated axillary nerve injury. When shoulder extension strength is compromised by extensive neuromuscular shoulder injury, reconstruction of both the anterior and posterior branches of the axillary nerve should be considered. Clinical Relevance By quantifying the biomechanical role of muscles during sub-maximal movement, in addition to quantifying muscle contributions to maximal shoulder strength, we can inform pre-operative planning and permit more accurate predictions of functional outcomes. PMID:23294649
Dexmedetomidine sedation in painful posterior segment surgery
Mansour, Ahmad; Taha, Samar
2012-01-01
Purpose To present a case series on the use of dexmedetomidine (Precedex) sedation in painful posterior segment surgery performed under topical anesthesia, similar to its use in cataract surgery. Methods A prospective review of cases that had posterior segment surgery under topical anesthesia and that needed sedation. Dexmedetomidine-loading infusion was 1 mcg/kg over 10 minutes, followed by a maintenance infusion (0.5 mcg/kg/h). Results Nine patients were operated on under topical anesthesia: two scleral buckle, five cryopexy, one scleral laceration, and one pars plana vitrectomy with very dense laser therapy in an albinotic fundus; six patients had retinal detachment. General or local anesthesia were not possible due to medical or ocular morbidities, use of anticoagulants, or the surgery plan changed intraoperatively when new pathologies were discovered. The surgeon achieved good surgical control in eight of nine cases, with one patient having ocular and bodily movements that were disturbing. Six patients had no pain, while three patients reported mild pain. No adverse effects were noted and all patients had successful surgical outcomes. Heart rate, blood pressure, and oxygen saturation were well controlled throughout the procedures. The most frequent adverse reactions of dexmedetomidine reported in the literature in less than 5% (hypotension, bradycardia, and dry mouth) were not recorded in the present study. Conclusion When a surgeon has planned to do a pars plana vitrectomy under topical anesthesia and the surgical situation dictates the addition of cryopexy, scleral buckle, or intense laser retinopexy, then sedation with dexmedetomidine can help in the control of ocular pain in the majority of cases, with good intraoperative and immediate postoperative hemodynamic control with the possibility of supplemental rescue analgesia. Dexmedetomidine, a sedative analgesic, is devoid of respiratory depressant effects, and its use in posterior segment surgery under topical anesthesia is reported here for the first time. PMID:23271889
Complications when augmenting the posterior maxilla.
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
Posterior reversible encephalopathy syndrome with documented hyponatraemia.
Aulakh, Puneet; Fatakhov, Eduard; Koch, Christopher Francis; Kapil, Shikha
2013-01-01
We present a case of a 78-year-old African-American man with a history of hypertension, and with no prior history of seizure. The patient presented with hypertensive urgency as well as stroke such as symptoms of confusion, seizure, postictal confusion, left hemianopsia and hyponatraemia. MRI findings were suggestive of posterior reversible encephalopathy syndrome (PRES). The patient was treated with appropriate medications with the resolution of his stroke-like symptoms. This case report discusses a patient with PRES, in the setting of hyponatraemia, and how prompt recognition may prevent permanent neurological sequela such as epilepsy. PMID:23904416
Posterior Reversible Encephalopathy Syndrome Associated with Hemorrhage
Rosalyn M. Aranas; Shyam Prabhakaran; Vivien H. Lee
2009-01-01
Background Posterior Reversible Encephalopathy Syndrome (PRES) is a clinico-radiological entity characterized by headache, encephalopathy,\\u000a visual disturbances, and seizures in association with reversible vasogenic edema on neuroimaging. Intracerebral hemorrhage\\u000a associated with PRES (PRES-ICH) is generally considered an atypical finding.\\u000a \\u000a \\u000a \\u000a Methods Retrospective case series.\\u000a \\u000a \\u000a \\u000a Results Seven patients were identified with PRES-ICH, four males and three females. The presenting clinical symptoms included headache\\u000a (2), encephalopathy (5),
Posterior reversible encephalopathy syndrome: the endothelial hypotheses.
Marra, A; Vargas, M; Striano, P; Del Guercio, L; Buonanno, P; Servillo, G
2014-05-01
Posterior reversible encephalopathy syndrome (PRES) is characterised by headache, visual disorders, seizures, altered mentation, consciousness disturbances and focal neurological signs. Initially described in patients with pre and eclampsia, severe hypertension, posterior reversible encephalopathy syndrome can occur in other clinical conditions such as infection, sepsis, shock, cancer chemotherapy, autoimmune diseases and hypercalcemia. Pathogenesis of brain lesions in PRES is not full understood and two opposite theories have been proposed. Both models are based on the central role of hypertension. According to the first theory, hypertension could cause a breakdown of the autoregulatory system in cerebral circulation, leading to brain edema. The second theory suggests that hypertension causes activation of autoregulatory system, which finally results in a vasoconstriction of brain vessels with hypoperfusion, ischemia and subsequent fluid leakage. However a large number of patients, with PRES, doesn't show hypertension. We here describe the hypothesis of the crucial role of endothelial dysfunction and activation in PRES pathogenesis. Our hypothesis offers a common pathogenetic mechanism in which every PRES-related condition can be set. In our model, the activation of immune system and the consequent endothelial activation start a molecular cascade which finally causes the production of molecules which alter the normal homeostasis of blood-brain barrier. This alteration consists in a weakening of brain vessel tight junctions, which allows fluid leakage and edema. In this scenario, hypertension would be an epiphenomenon of the underlying mechanism and not the cause and, for this reason, it can be present or not in PRES. PMID:24613735
Sampling Networks from Their Posterior Predictive Distribution
Goyal, Ravi; De Gruttola, Victor; Blitzstein, Joseph
2014-01-01
Recent research indicates that knowledge about social networks can be leveraged to increase efficiency of interventions (Valente, 2012). However, in many settings, there exists considerable uncertainty regarding the structure of the network. This can render the estimation of potential effects of network-based interventions difficult, as providing appropriate guidance to select interventions often requires a representation of the whole network. In order to make use of the network property estimates to simulate the effect of interventions, it may be beneficial to sample networks from an estimated posterior predictive distribution, which can be specified using a wide range of models. Sampling networks from a posterior predictive distribution of network properties ensures that the uncertainty about network property parameters is adequately captured. The tendency for relationships among network properties to exhibit sharp thresholds has important implications for understanding global network topology in the presence of uncertainty; therefore, it is essential to account for uncertainty. We provide detail needed to sample networks for the specific network properties of degree distribution, mixing frequency, and clustering. Our methods to generate networks are demonstrated using simulated data and data from the National Longitudinal Study of Adolescent Health. PMID:25339990
Paediatric epilepsy surgery in the posterior cortex: a study of 62 cases.
Liava, Alexandra; Mai, Roberto; Tassi, Laura; Cossu, Massimo; Sartori, Ivana; Nobili, Lino; Lo Russo, Giorgio; Francione, Stefano
2014-06-01
Past surgical series have emphasized the diagnostic complexity of posterior cortex epilepsy. Available data are sparse, especially in children, and most published series report a high number of surgical failures and post-operative neurological deficits. In this article, we present a paediatric cohort of 62 children who underwent surgery for drug resistant posterior cortex epilepsy before the age of 16 years with a mean post-operative follow-up of 6.94 years (range: 2-16). Mean age at epilepsy onset was 3.2 years and 28 children (45%) had onset before 1 year of age. The mean age at surgery was 7.9 years (range: 1-16). Daily seizures were present in 63% of children. MRI was positive in 58 cases (93.5%) and invasive stereo-EEG was judged mandatory in 24/62 (39%) of patients. Surgery was confined to the parietal lobe in 11 children, the occipital lobe in 8, the occipito-parietal region in four, the occipito-temporal region in 18, and involved both the temporal and parietal lobes in the remaining 21. Following surgery, 53 subjects (85.5%) remained seizure-free and among those who underwent a SEEG procedure, 75% achieved seizure freedom. Focal cortical dysplasia was the most frequent histopathological diagnosis (50%), followed by tumoural (24%) and gliotic lesions (14.5%). An older age at epilepsy onset, the presence of a rather restricted epileptogenic area, and a complete resection of the epileptogenic zone were predictive of a favourable surgical outcome. These results demonstrate that a good surgical outcome is possible in children with drug resistant posterior cortex epilepsy. Accurate analysis of the chronology of ictal semiology and electrophysiological features, viewed in the context of the complete electroclinical pattern, provides a topographical orientation for posterior cortex epilepsy and, together with the presence of a lesion detectable on imaging, may improve the rate of surgical success of posterior cortex epilepsy at paediatric age. PMID:24853765
The absent posterior drawer test in some acute posterior cruciate ligament tears of the knee
Jack C. Hughston
1988-01-01
Over a 10 year period, 24 of 54 acute PCL tears in cases of straight medial instability demonstrated an absent or an equivocal posterior drawer test. Most of these (22, 91.6%) were contact injuries, and in the 11 cases where the mechanism of injury was known (45.8%), were incurred by a blow to the outer aspect of the leg while
NSDL National Science Digital Library
The Probability Web is a metasite located at Carleton College. It deals with probability theory and applications, providing links to abstracts, journals (not all free), electronic mailing lists, newsgroups, people, jobs, societies, software, books, and conferences. The site also has a basic search engine. Available in graphical or non-graphical versions, The Probability Web is a rich resource with many informative and interesting links for mathematicians.
NSDL National Science Digital Library
Dr. Jennifer J Taylor (Washington University)
2009-03-30
This is a lab for middle school or high school students exploring how probability applies to genetics. Students collect data using beads and a coin as examples of alleles. The analysis questions walk students through the steps of expressing probabilities as a fraction or as a decimal. The students are also asked to draw a Punnett square which relates probability to offspring of a particular cross.
Statistics and Probability Tutorial
NSDL National Science Digital Library
Berman, Harvey
This tutorial, created by Harvey Berman of Stat Trek, provides a basic introduction to many topics in statistics and probability. Topics include: sets and subsets, statistical experiments, counting, basic probability rules, Bayes' theorem, probability distributions, discrete versus continuous, binomial, negative binomial, hypergeometric, multinomial, Poisson, normal, sampling theory, central tendency, variability, sampling distributions, t-distribution, Chi-square distribution, F-distribution, estimation problems, hypothesis testing, power, survey sampling, simple random samples, stratified samples, cluster samples, sample size. This is a general overview of statistics and probability. It is geared towards a high school advanced placement level.
Simon Saunders
2004-12-24
Probabilities may be subjective or objective; we are concerned with both kinds of probability, and the relationship between them. The fundamental theory of objective probability is quantum mechanics: it is argued that neither Bohr's Copenhagen interpretation, nor the pilot-wave theory, nor stochastic state-reduction theories, give a satisfactory answer to the question of what objective probabilities are in quantum mechanics, or why they should satisfy the Born rule; nor do they give any reason why subjective probabilities should track objective ones. But it is shown that if probability only arises with decoherence, then they must be given by the Born rule. That further, on the Everett interpretation, we have a clear statement of what probabilities are, in terms of purely categorical physical properties; and finally, along lines recently laid out by Deutsch and Wallace, that there is a clear basis in the axioms of decision theory as to why subjective probabilities should track these objective ones. These results hinge critically on the absence of hidden-variables or any other mechanism (such as state-reduction) from the physical interpretation of the theory. The account of probability has traditionally been considered the principal weakness of the Everett interpretation; on the contrary it emerges as one of its principal strengths.
Posterior left atrial–esophageal relationship throughout the cardiac cycle
Jasbir Sra; David Krum; Angela Malloy; Atul Bhatia; Ryan Cooley; Zalmen Blanck; Anwer Dhala; Alfred J. Anderson; Masood Akhtar
2006-01-01
Background Radiofrequency energy delivered throughout the cardiac cycle has the potential to cause thermal injury to the esophagus if the anatomical relationship between the posterior left atrium and the esophagus changes during cardiac motion.Objective To assess the posterior left atrial–esophageal relationship throughout the cardiac cycle.Methods In this study, the anatomical relationship between the posterior left atrium and the esophagus was assessed throughout the
Minimally invasive surgical approach to treat posterior urethral diverticulum.
Alsowayan, Ossamah; Almodhen, Fayez; Alshammari, Ahmed
2015-01-01
Urethral diverticulum is a localized saccular or fusiform out-pouching of the urethra. It may occur at any point along the urethra in both male and females. Male urethral diverticulum is rare, and could be either congenital or acquired, anterior or posterior. The mainstay treatment of posterior urethral diverticulum (PUD) is the open surgical approach. Here we discuss our minimally invasive surgical approach (MIS) in managing posterior urethral diverticulum. PMID:25834967
Posterior Cruciate Ligament: Focus on Conflicting Issues
Lee, Yong Seuk
2013-01-01
There is little consensus on how to optimally reconstruct the posterior cruciate ligament (PCL) and the natural history of injured PCL is also unclear. The graft material (autograft vs. allograft), the type of tibial fixation (tibial inlay vs. transtibial tunnel), the femoral tunnel position within the femoral footprint (isometric, central, or eccentric), and the number of bundles in the reconstruction (1 bundle vs. 2 bundles) are among the many decisions that a surgeon must make in a PCL reconstruction. In addition, there is a paucity of information on rehabilitation after reconstruction of the PCL and posterolateral structures. This article focused on the conflicting issues regarding the PCL, and the scientific rationales behind some critical points are discussed. PMID:24340144
Asymptomatic posterior mediastinal teratoma diagnosed incidentally.
Jaiswal, Riddhi; Rani, Poonam; Devenraj, Vijayant
2014-01-01
We present a young patient with occasional chest pain and an incidentally found posterior mediastinal mass on radiology which was confirmed as mature teratoma on histopathology. The gross specimen received in the department of pathology was globular measuring 9.0×7.0×5.5 cm and varying in consistency from soft cystic to firm. Cut surface showed numerous hair entangled in pultaceous material. Representative sections were taken and stained with H&E stain. Histopathology revealed haphazardly distributed mature derivatives of all the three germ layers comprising of epidermis, pilo sebaceous units, nerve bundles (ectodermal), cartilage, bone, salivary gland clusters, blood vessels, muscle bundles, fibrous tissue infiltrated by foreign body giant cells, lymphoid follicles (mesodermal) and pseudostratified columnar epithelium (mesodermal), thus establishing the diagnosis of mature teratoma. PMID:24654248
Endoscopic Correction of Vesicoureteral Reflux Secondary to Posterior Urethral Valves
Prem Puri; Rajendra Kumar
1996-01-01
PurposeWe review our experience with children with high grade vesicoureteral reflux secondary to posterior urethral valves treated endoscopically with subureteral polytetrafluoroethylene (Teflon) injection.
Posterior Circulation Stroke: Animal Models and Mechanism of Disease
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
Posterior circulation stroke: animal models and mechanism of disease.
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
Intro Probability Rabbits Description Predictions Ontology of Earthquake Probability: Metaphor
Stark, Philip B.
Intro Probability Rabbits Description Predictions Ontology of Earthquake Probability: Metaphor be abandoned in favor of common sense. #12;Intro Probability Rabbits Description Predictions Earthquake not random. Wm. ShakesEarth #12;Intro Probability Rabbits Description Predictions Earthquake Poker
Statistical Applets: Probability
NSDL National Science Digital Library
Duckworth, William
Created by authors Duckworth, McCabe, Moore and Sclove for W.H. Freeman and Co., this applet simulates flipping a coin to show how observed probability approaches true probability over time. It accompanies "Â?Â?Practice of Business Statistics," but can be used without this text. Even though brief, this is still a fine resource for an introductory statistics course.
Interactive Applet: Probability
NSDL National Science Digital Library
This applet, created by McGraw-Hill Higher Education, is designed to help students visualize how observed probability approaches true probability as sample size increases by simulating rolling dice. It accompanies "Statistical Techniques in Business and Economics," but does not require use of the text. This is a fun lesson for students wanting to delve deeper into the world of statistics.
NSDL National Science Digital Library
Ms. Johnson
2008-04-30
Can YOU figure out the probability? Take a pick! Try to Guess the Number in as few tries as possible! There are so many possibilities!! Try to figure out all the possible disguises!! Help the fish, and find out the Probability! ...
Paris-Sud XI, Université de
) Generalized Logistic (GLO), (iv) Generalized Normal (GN), and (v) Gener- alized Pareto (GPA) distributionsHESSD 4, 957981, 2007 Probability distribution of flood flows in Tunisia H. Abida and M. Ellouze System Sciences Probability distribution of flood flows in Tunisia H. Abida 1 and M. Ellouze 2 1
Knowledge, probability, and adversaries
Joseph Y. Halpern; Mark FL Tuttle
1989-01-01
What should it mean for an agent to know or believe an assertion is true with probability .99? Different papers (FH88, FZ88, HMT88) give differ- ent answers, choosing to use quite different, probabil- ity spaces when computing the probability an agent assigns to an event. We show that each choice can be understood in terms of a betting game, and
Lin, Xiaodong
will draw from online resources and will be posted to BlackBoard. Recommended Textbook DasGupta, A. (2010Gupta, A. (2011). Probability for statistics and machine learning [electronic resource]: Fundamentals). Fundamentals of probability: A first course. New York: Springer. All references are available online or freely
NSDL National Science Digital Library
Abebe, Asheber
This resource, created by the statistics departed at Western Michigan University, helps define and explain binomial probability. It includes examples and exercises for the learner which facilitate further understanding of the subject. Overall, this specific site is perfect for users studying statistics, more specifically probability testing.
Probability Forecasting in Meteorology
Allan H. Murphy; Robert L. Winkler
1984-01-01
Efforts to quantify the uncertainty in weather forecasts began more than 75 years ago, and many studies and experiments involving objective and subjective probability forecasting have been conducted in meteorology in the intervening period. Moreover, the U.S. National Weather Service (NWS) initiated a nationwide program in 1965 in which precipitation probability forecasts were formulated on an operational basis and routinely
ERIC Educational Resources Information Center
Barnes, Bernis, Ed.; And Others
This teacher's guide to probability and statistics contains three major sections. The first section on elementary combinatorial principles includes activities, student problems, and suggested teaching procedures for the multiplication principle, permutations, and combinations. Section two develops an intuitive approach to probability through…
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.
MODELLING DISCRETE INPUT PROBABILITY DISTRIBUTIONS
Strelen, Christoph
MODELLING DISCRETE INPUT PROBABILITY DISTRIBUTIONS Johann Christoph Strelen Rheinische Friedrich Probability Distributions, Dis- crete Probability Distributions, Genetic Algorithm, Inverse Transformation Method. ABSTRACT Sometimes input probability distributions for stochastic models are not so simple
NSDL National Science Digital Library
With many computer users developing their own Web sites, some of them may be interested in monitoring how search engines may be ranking their site. This latest edition of Accurate Monitor may prove useful, as it allows individuals to find the position of their Web site in search engines like Altavista and Google. Additionally, Accurate Monitor can generate advanced statistics and monitor plugins, along with providing a flexible interface system. This version of Accurate Monitor is compatible with all systems running Windows 95 and higher.
Cervical spinal cord infarction after posterior fossa surgery: a case-based update
Juan F. Martínez-Lage; María-José Almagro; Virginia Izura; Cristina Serrano; Antonio M. Ruiz-Espejo; Isabel Sánchez-del-Rincón
2009-01-01
Background Several positions are currently utilized for operating patients with posterior fossa lesions. Each individual position has\\u000a its own risks and benefits, and none has demonstrated its superiority. A dreaded, and probably underreported, complication\\u000a of these procedures is cervical cord infarction with quadriplegia.\\u000a \\u000a \\u000a \\u000a Discussion We reviewed eight previous reported instances of this devastating complication aimed at ascertaining its pathogenesis to suggest\\u000a preventive
Probability Theory as Logic: Data Assimilation for Multiple Source Reconstruction
NASA Astrophysics Data System (ADS)
Yee, Eugene
2012-03-01
Probability theory as logic (or Bayesian probability theory) is a rational inferential methodology that provides a natural and logically consistent framework for source reconstruction. This methodology fully utilizes the information provided by a limited number of noisy concentration data obtained from a network of sensors and combines it in a consistent manner with the available prior knowledge (mathematical representation of relevant physical laws), hence providing a rigorous basis for the assimilation of this data into models of atmospheric dispersion for the purpose of contaminant source reconstruction. This paper addresses the application of this framework to the reconstruction of contaminant source distributions consisting of an unknown number of localized sources, using concentration measurements obtained from a sensor array. To this purpose, Bayesian probability theory is used to formulate the full joint posterior probability density function for the parameters of the unknown source distribution. A simulated annealing algorithm, applied in conjunction with a reversible-jump Markov chain Monte Carlo technique, is used to draw random samples of source distribution models from the posterior probability density function. The methodology is validated against a real (full-scale) atmospheric dispersion experiment involving a multiple point source release.
NSDL National Science Digital Library
The Math Forum
1998-01-01
These pages present, in terms of a fictional story based on true events, the problem that inspired the development of mathematical probability in Renaissance Europe by French mathematicians Pierre de Fermat and Blaise Pascal. Two equally skilled players are interrupted while playing a game of chance for a certain amount of money. Given the score of the game at that point, how should the stakes be divided? Outlined here is, first, the particular solution and then the general solution based on a central concept of probability, equally probable outcomes.
Chapter 5 Discrete Probability Distributions
Hong, Don
Chapter 5 Discrete Probability Distributions 5.1 Introduction 5.2 Probability Distributions 5 random variable X has a countable number of possible values. The probability distribution of X lists probability, is an example of a probability distribution. Number of heads Probability 0 0.25 1 0.50 2 0
Acute combined posterior cruciate and posterolateral instability of the knee
Champ L. Baker; Lyle A. Norwood; Jack C. Hughston
1984-01-01
This report concerns 13 consecutive patients (13 knees) who underwent operative treatment for acute combined posterior cruciate and posterolateral instabil ity due to combined injury to the posterior cruciate ligament and the arcuate ligament complex. Our pur pose was to examine the method of diagnosis and the results in these patients. There were 12 males and 1 female (average age,
Spontaneous posterior capsular rupture with lens dislocation in pseudoexfoliation syndrome.
Takkar, Brijesh; Mahajan, Deepankur; Azad, Shorya; Sharma, Yog; Azad, Rajvardhan
2013-07-01
Spontaneous posterior capsule rupture is a very rare entity and its association with lens-nucleus dislocation even more. Herein we report such a case of spontaneous posterior capsule rupture with lens dislocation in a case of Pseudoexfoliation Syndrome. PMID:23627342
Assessing the Calibration of Naive Bayes' Posterior Paul N. Bennett
Assessing the Calibration of Naive Bayes' Posterior Estimates Paul N. Bennett September 12, 2000 In this paper, we give evidence that the posterior distribution of Naive Bayes goes to zero or one exponen likelihood scheme, and the results are evaluated. Email: pbennett+@cs.cmu.edu #12; Keywords: Naive Bayes
Isolated posterior cruciate ligament reconstructionLong-term results
A. Brant Lipscomb; Allen F. Anderson; Emily D. Norwig; W. David Hovis; David L. Brown
1993-01-01
From 1973 to 1987, 28 patients seen at our institution sustained isolated posterior cruciate ligament tears. Of these 28 patients, 25 were reevaluated at an average followup of 7 years and 1 month after secondary recon struction of the posterior cruciate ligament using the semitendinosus and gracilis tendons alone or with an extraarticular procedure.Subjectively, 22 of 25 patients related no
Myogenic Failure in Posterior Urethral Valve Disease: Real or Imagined?
Rosalia Misseri; Andrew J. Combs; Mark Horowitz; Jeffrey M. Donohoe; Kenneth I. Glassberg
2002-01-01
PurposeIt has been suggested that hypocontractility or myogenic failure develops in older boys with a history of 9 posterior urethral valved as the hyperactive, poorly compliant bladders decompensate with age. Also a much higher prevalence of myogenic failure has been reported than we have observed. We determine the prevalence of myogenic failure in boys with a posterior urethral valve and
Posterior fossa meningiomas: surgical experience in 161 cases
Fabio Roberti; Laligam N Sekhar; Chandrasekar Kalavakonda; Donald C Wright
2001-01-01
BACKGROUNDWe report the clinical, radiological, and surgical findings of patients with posterior fossa meningiomas surgically treated at our institution over the last 6 years.METHODSWe reviewed 161 consecutive cases of posterior fossa meningiomas operated on between April 1993 and April 1999 at The George Washington University Medical Center.RESULTSThere were 128 female and 33 male patients (mean age 47 years, range of
Investigation of occiput posterior delivery by intrapartum sonography
S. Akmal; E. Tsoi; R. Howard; E. Osei; K. H. Nicolaides
2004-01-01
Objective To investigate if occiput posterior delivery is the consequence of persistence of an initial occiput posterior position or malrotation from an initial occiput anterior or transverse position. Methods This was a cross-sectional study involving transabdominal sonography to determine fetal occipital position in 918 singleton pregnancies with cephalic presentation in active labor at 37-42 weeks of gestation. The relationship between
Minimally Invasive Strabismus Surgery for Rectus Muscle Posterior Fixation
Daniel S. Mojon
2009-01-01
Aims: To present a novel, minimally invasive strabismus surgery (MISS) technique for rectus muscle posterior fixation. Methods: This study reports the results of 32 consecutive MISS rectus muscle posterior fixation surgeries performed on 19 patients by applying only two small L-shaped openings where the two retroequatorial scleromuscular sutures were placed. Results: On the first postoperative day, in primary position, redness
Benign Ependymomas of the Posterior Fossa in Childhood
Tadanori Tomita; David G. McLone; Lakshmi Das; William N. Brand
1988-01-01
A series of 22 infants and children with posterior fossa benign ependymomas treated surgically during the past 12 years is presented. All patients were operated on with posterior fossa craniotomy: visible total resection in 10, subtotal resection in 9, partial resection in 2 and biopsy only in 1. One patient (4.5%) died shortly after surgery. Only 5 patients had documented
How Does Wnt Signaling Posteriorize the Neural Plate?
Lee, Jeffrey Joon Taek
2013-02-04
HOW DOES Wnt SIGNALING POSTERIORIZE THE NEURAL PLATE? An Undergraduate Research Scholars Thesis By JEFFREY JOON TAEK LEE Submitted to Honors and Undergraduate Research Texas A&M University In partial fulfillment of the requirements...??????????????????????........19 REFERENCES..............................................................................................................................21 2 ABSTRACT How does the Wnt signaling posteriorize the neural plate? (May 2013) Jeffrey Joon...
Posterior Fossa Syndrome: Identifiable Risk Factors and Irreversible Complications
Deborah Doxey; Derek Bruce; Frederick Sklar; Dale Swift; Ken Shapiro
1999-01-01
Cerebellar mutism was first described by Rekate et al. in 1985 as a transient condition which occurs after posterior fossa operations in children. Posterior fossa syndrome (PFS) and cerebellar mutism are often used interchangeably in the literature. In our experience, we found cerebellar mutism to be a reversible component of a persistent neurologic syndrome. The cause and identifiable risk factors
Magnetic Resonance Imaging of Pediatric Posterior Fossa Tumors
Robert A. Zimmerman; Larissa T. Bilaniuk; Susan Rebsamen
1992-01-01
MR detected abnormality in all 115 pediatric patients who subsequently had pathologically proven posterior fossa tumors. In 114, the initial magnetic resonance (MR) diagnosis was that of brain tumor. In 1, with less than 1-cm2 area of gadolinium enhancement, the significance of the initial finding was uncertain. Common posterior fossa tumor subgroups (brainstem gliomas, cerebellar astrocytomas, primitive neuroectodermal tumors, and
Posterior regeneration in Isodiametra pulchra (Acoela, Acoelomorpha)
2013-01-01
Introduction Regeneration is a widespread phenomenon in the animal kingdom, but the capacity to restore damaged or missing tissue varies greatly between different phyla and even within the same phylum. However, the distantly related Acoelomorpha and Platyhelminthes share a strikingly similar stem-cell system and regenerative capacity. Therefore, comparing the underlying mechanisms in these two phyla paves the way for an increased understanding of the evolution of this developmental process. To date, Isodiametra pulchra is the most promising candidate as a model for the Acoelomorpha, as it reproduces steadily under laboratory conditions and is amenable to various techniques, including the silencing of gene expression by RNAi. In order to provide an essential framework for future studies, we report the succession of regeneration events via the use of cytochemical, histological and microscopy techniques, and specify the total number of cells in adult individuals. Results Isodiametra pulchra is not capable of regenerating a new head, but completely restores all posterior structures within 10 days. Following amputation, the wound closes via the contraction of local muscle fibres and an extension of the dorsal epidermis. Subsequently, stem cells and differentiating cells invade the wound area and form a loosely delimited blastema. After two days, the posterior end is re-patterned with the male (and occasionally the female) genital primordium being apparent. Successively, these primordia differentiate into complete copulatory organs. The size of the body and also of the male and female copulatory organs, as well as the distance between the copulatory organs, progressively increase and by nine days copulation is possible. Adult individuals with an average length of 670 ?m consist of approximately 8100 cells. Conclusion Isodiametra pulchra regenerates through a combination of morphallactic and epimorphic processes. Existing structures are “re-modelled” and provide a framework onto which newly differentiating cells are added. Growth proceeds through the intercalary addition of structures, mirroring the embryonic and post-embryonic development of various organ systems. The suitability of Isodiametra pulchra for laboratory techniques, the fact that its transcriptome and genome data will soon be available, as well as its small size and low number of cells, make it a prime candidate subject for research into the cellular mechanisms that underlie regeneration in acoelomorphs. PMID:24160844
Understanding Experimental Probability
NSDL National Science Digital Library
The Shodor Education Foundation, Inc.
2007-12-12
Experiment with experimental probability using a fixed size section spinner, a variable section spinner, 2 regular 6-sided number cubes or design your own number cubes. Appropriate for elementary grades.
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.
Watkins, Joseph C.
are not identical twins, the sex of each child is independent and each sex has probability 1/2. (a) In the cases population. Identical (monogygotic) twins make up 8% of all twins. Identical twins always have the same sex
Accurate Evaluation of Quantum Integrals
NASA Technical Reports Server (NTRS)
Galant, David C.; Goorvitch, D.
1994-01-01
Combining an appropriate finite difference method with Richardson's extrapolation results in a simple, highly accurate numerical method for solving a Schr\\"{o}dinger'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.
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.
NSDL National Science Digital Library
Nicholas Exner
1999-01-01
This applet can be used to observe how probability of outcomes for a multistage event determines the final result. The applet simulates the launch of a three-stage rocket that requires all three stages to pass tests before takeoff. The student can vary the probability of passing at each stage from 0 to 100 percent. The applet reports the overall success rate as a percent and the cumulative number of successful and failed launches. Copyright 2005 Eisenhower National Clearinghouse
Vitreous changes after neodymium-YAG laser irradiation of the posterior lens capsule or mid-vitreous
Lerman, S.; Thrasher, B.; Moran, M.
1984-04-01
Exposure of four monkey and 26 rabbit eyes to neodymium-YAG laser irradiation to the posterior lens capsule or the mid-vitreous area clearly demonstrated significant vitreous changes (liquefaction) as measured by viscosity analyses and proton relaxation studies. We found marked molecular alterations in the vitreous of the exposed eye compared with the contralateral control (unirradiated) eye. These alterations, occurring immediately after laser treatment, were probably the result of acoustic transients accompanying the laser irradiation.
Mitral Valve Mechanics Following Posterior Leaflet Patch Augmentation
Rahmani, Azadeh; Rasmussen, Ann Q.; Honge, Jesper L.; Ostli, Bjorn; Levine, Robert A.; Hagège, Albert; Nygaard, Hans; Nielsen, Sten L.; Jensen, Morten O.
2013-01-01
Background and aim of the study Attention towards the optimization of mitral valve repair methods is increasing. Patch augmentation is one strategy used to treat functional ischemic mitral regurgitation (FIMR). The study aim was to investigate the force balance changes in specific chordae tendineae emanating from the posterior papillary muscle in a FIMR-simulated valve, following posterior leaflet patch augmentation. Methods Mitral valves were obtained from 12 pigs (body weight 80 kg). An in vitro test set-up simulating the left ventricle was used to hold the valves. The left ventricular pressure was regulated with water to simulate different static pressures during valve closure. A standardized oval pericardial patch (17 × 29 mm) was introduced into the posterior leaflet from mid P2 to the end of the P3 scallop. Dedicated miniature transducers were used to record the forces exerted on the chordae tendineae. Data were acquired before and after 12 mm posterior and 5 mm apical posterior papillary muscle displacement to simulate the effect from one of the main contributors of FIMR, before and after patch augmentation. Results The effect of displacing the posterior papillary muscle induced tethering on the intermediate chordae tendineae to the posterior leaflet, and resulted in a 39.8% force increase (p = 0.014). Posterior leaflet patch augmentation of the FIMR valve induced a 31.1% force decrease (p = 0.007). There was no difference in force between the healthy and the repaired valve simulations (p = 0.773). Conclusion Posterior leaflet patch augmentation significantly reduced the forces exerted on the intermediate chordae tendineae from the posterior papillary muscle following FIMR simulation. As changes in chordal tension lead to a redistribution of the total stress exerted on the valve, patch augmentation may have an adverse long-term influence on mitral valve function and remodeling. PMID:23610985
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.
Decision Salience Signals in Posterior Cingulate Cortex
Heilbronner, Sarah R.; Hayden, Benjamin Y.; Platt, Michael L.
2011-01-01
Despite its phylogenetic antiquity and clinical importance, the posterior cingulate cortex (CGp) remains an enigmatic nexus of attention, memory, motivation, and decision making. Here we show that CGp neurons track decision salience – the degree to which an option differs from a standard – but not the subjective value of a decision. To do this, we recorded the spiking activity of CGp neurons in monkeys choosing between options varying in reward-related risk, delay to reward, and social outcomes, each of which varied in level of decision salience. Firing rates were higher when monkeys chose the risky option, consistent with their risk-seeking preferences, but were also higher when monkeys chose the delayed and social options, contradicting their preferences. Thus, across decision contexts, neuronal activity was uncorrelated with how much monkeys valued a given option, as inferred from choice. Instead, neuronal activity signaled the deviation of the chosen option from the standard, independently of how it differed. The observed decision salience signals suggest a role for CGp in the flexible allocation of neural resources to motivationally significant information, akin to the role of attention in selective processing of sensory inputs. PMID:21541308
Cognitive Control Signals in Posterior Cingulate Cortex
Hayden, Benjamin Y.; Smith, David V.; Platt, Michael L.
2010-01-01
Efficiently shifting between tasks is a central function of cognitive control. The role of the default network – a constellation of areas with high baseline activity that declines during task performance – in cognitive control remains poorly understood. We hypothesized that task switching demands cognitive control to shift the balance of processing toward the external world, and therefore predicted that switching between the two tasks would require suppression of activity of neurons within the posterior cingulate cortex (CGp). To test this idea, we recorded the activity of single neurons in CGp, a central node in the default network, in monkeys performing two interleaved tasks. As predicted, we found that basal levels of neuronal activity were reduced following a switch from one task to another and gradually returned to pre-switch baseline on subsequent trials. We failed to observe these effects in lateral intraparietal cortex, part of the dorsal fronto-parietal cortical attention network directly connected to CGp. These findings indicate that suppression of neuronal activity in CGp facilitates cognitive control, and suggest that activity in the default network reflects processes that directly compete with control processes elsewhere in the brain. PMID:21160560
Representation of numerosity in posterior parietal cortex
Roitman, Jamie D.; Brannon, Elizabeth M.; Platt, Michael L.
2012-01-01
Humans and animals appear to share a similar representation of number as an analog magnitude on an internal, subjective scale. Neurological and neurophysiological data suggest that posterior parietal cortex (PPC) is a critical component of the circuits that form the basis of numerical abilities in humans. Patients with parietal lesions are impaired in their ability to access the deep meaning of numbers. Acalculiac patients with inferior parietal damage often have difficulty performing arithmetic (2 + 4?) or number bisection (what is between 3 and 5?) tasks, but are able to recite multiplication tables and read or write numerals. Functional imaging studies of neurologically intact humans performing subtraction, number comparison, and non-verbal magnitude comparison tasks show activity in areas within the intraparietal sulcus (IPS). Taken together, clinical cases and imaging studies support a critical role for parietal cortex in the mental manipulation of numerical quantities. Further, responses of single PPC neurons in non-human primates are sensitive to the numerosity of visual stimuli independent of low-level stimulus qualities. When monkeys are trained to make explicit judgments about the numerical value of such stimuli, PPC neurons encode their cardinal numerical value; without such training PPC neurons appear to encode numerical magnitude in an analog fashion. Here we suggest that the spatial and integrative properties of PPC neurons contribute to their critical role in numerical cognition. PMID:22666194
Posterior endoscopic discectomy: Results in 300 patients
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
Vitamin D deficiency and posterior subcapsular cataract
Brown, Craig J; Akaichi, Faical
2015-01-01
Purpose To evaluate risk factors associated with posterior subcapsular cataract (PSC) development and the relationship between vitamin D deficiency and etiology of PSC. Methods Of 195 consecutive patients from a private ophthalmology practice, diagnosed with PSC, serum vitamin D3 (25-OH D) levels were obtained for 175, and associations among risk factors, comorbidities, and PSC were assessed. Results In all 175 PSC patients, mean 25-OH D levels were low (24 ng/mL ±11 SD) compared with age/sex-matched standards. Significant differences in 25-OH D levels were noted between PSC subjects taking/not taking calcium supplements, systemic steroids, osteoporosis medications, etc. Alone, smoking status and calcium channel blockers and/or topical steroids use made no significant difference in PSC subjects 25-OH D levels, but two or more of these factors were associated with lowered levels of 25-OH D (P<0.001). Low vitamin D was correlated with female sex, autoimmune disease, and non-skin cancer diagnosis, but not with age, or other comorbidities or medication use. In five early-stage PSC patients taking 5,000 IU of 25-OH D daily for vitamin D deficiency, there was resolution of their cataracts during the 2-year follow-up period. Conclusion Vitamin D levels for most PSC patients fell below the 30 ng/mL calcium homeostasis threshold. Some comorbidities and non-ophthalmic interventions are associated with the development of PSC at less depressed levels of 25-OH D. In this series, vitamin D deficiency was associated with PSC cataract, suggesting that raising the level of vitamin D intake may reduce PSC incidence. PMID:26124632
Constructive Artificial Intelligence Probability
Polani, Daniel
,4 0,6 0,8 1 FatalityProbability(PD) pdf PD 7 106.1 ( ) )p(PD 1 10949 - = . 0 0,1 0,2 0,3 0,4 0,5 0 1 10018 - = . Monte Carlo: ( ) 1 1036.1 - =)( .).( CMDPp ( ) )p(PD 1 1093.2 - = Monte CarloDistributionf(D) 0 0,2 0,4 0,6 0,8 1 FatalityProbability(PD) pdf PD -- arkovarkov case study: #12; ( ) )p(PD
Paris-Sud XI, Université de
Posterior concentration rates for empirical Bayes procedures, with applications to Dirichlet posterior concentration rates for data-dependent priors (or empirical Bayes approaches). We aim at providing multiplicative intensity with priors not depending on the data. Keywords: Empirical Bayes, posterior
Probability Out Of Determinism Michael Strevens
Strevens, Michael
;1. Deterministic Probability A deterministic probability is a physical probability sincerely ascribed by some in their "sincerity" concerning the probabilities' observer-independent existence). Deterministic probability is
Jonny Heeley's Masterclass - Probability
NSDL National Science Digital Library
teachers.tv
2009-02-17
In this video, award-winning Jonny Heeley offers some inspiring ways of simplifying probability. He uses a variety of games and challenges to excite and entertain his group of students. His ideas also provide teachers with some accessible new methods of teaching the subject.
Probability estimation for PPM
W. J. Teahan
1995-01-01
The state of the art in lossless text compression is the PPM data compression scheme. Two approachesto the problem of selecting the context models used in the scheme are described. One usesan a priori upper bound on the lengths of the contexts, while the other method is unbounded. Severaltechniques that improve the probability estimation are described, including four new methods:
Watkins, Joseph C.
of tagged fish in the second capture. 2. Hemophilia A is a sex linked recessive trait on the X chromosome for hemophilia What fraction of the male popu- lation have hemophilia? (b) A female has hemophilia if she received two alleles for hemophilia. Assuming that the probability of receiving the allele is 0
PROBABILITY SMOOTHING Djoerd Hiemstra
Hiemstra, Djoerd
PROBABILITY SMOOTHING Djoerd Hiemstra University of Twente http://www.cs.utwente.nl/hiemstra University, August 1998. [2] Hugo Zaragoza, Djoerd Hiemstra, Michael Tipping, and Stephen Robertson. Bayesian] ChengXiang Zhai and John Lafferty. A study of smoothing methods for language models applied
NSDL National Science Digital Library
Kyle Siegrist
This resource consists of a Java applet and Expository text. The applet simulates the probability plot that compares the empirical quantiles of a sample from a sampling distribution to the distribution quantiles of a test distribution. The sampling distribution, test distribution, and sample size can be specified.
DISCUSS: Probability with Dice
NSDL National Science Digital Library
Cologne-Brookes, Nicki
This module, by Neville Hunt and Nicki Cologne-Brookes of Coventry University, teaches probability through dice simulations. Students will use Excel spreadsheets to simulate experiments of rolling 1 die, taking the sum of 2 dice, taking the difference of 2 dice, and rolling many dice. Instructions for creating a dice simulation in Excel are also given.
G. A. Quznetsov
2010-09-14
The propositional logic is generalized on the real numbers field. The logical analog of the Bernoulli independent tests scheme is constructed. The variant of the nonstandard analysis is adopted for the definition of the logical function, which has all properties of the classical probability function. The logical analog of the Large Number Law is deduced from properties of this function.
Watkins, Joseph C.
.25% of the women are color blind. (a) Assuming that the population is made up 1/2 men and 1/2 women, find the fraction of the population that is color blind. (b) If a person chosen at random is color blind, find the probability that the person is female. (c) If six randomly chosen individuals are color blind, find
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…
EXPECTATIONS: POINTESTIMATES, PROBABILITY DISTRIBUTIONS, CONFIDENCE,
Chen, Yiling
EXPECTATIONS: POINTESTIMATES, PROBABILITY DISTRIBUTIONS, CONFIDENCE, AND FORECASTS* David and probability distributions from nonexperts. As in the previous literature, respondents are overconfident. My captures "bestestimate" pointestimates and then probability distributions from nonexperts on upcoming
Makino, Arturo; Aponte Tinao, Luis; Ayerza, Miguel Angel; Pascual Garrido, Cecilia; Costa Paz, Matias; Muscolo, Domingo Luis
2006-06-01
Techniques for the reconstruction of knee ligaments must restore the injured knee to a satisfactory level of performance. For this, a precise anatomic reconstruction is necessary. Many arthroscopic techniques for reconstruction of the posterior cruciate ligament (PCL) have been reported to restore the normal anatomy of the intact PCL using a double-bundle reconstruction with a Y-shaped tendon graft (2 femoral tunnel and 1 tibial tunnel). However, this procedure is sometimes difficult because the graft must be tightened in different grades of flexion to obtain complete strength of both bundles. We thought that double-bundle PCL reconstruction using double-double tunnels (2 femoral and 2 tibial tunnels) would allow an anatomic reconstruction, restoring better knee biomechanics, and probably improving patient outcome. PMID:16762716
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?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
Meng Fanbin; Hao Yanling; Zhou Weidong; Sun Feng
2009-01-01
The random finite set (RFS) approach offers a natural and smart means to model multi-target and measurements received by the multi-sensor. The probability hypothesis density (PHD) filter propagates a multi-target statistical first moment, the PHD in place of the full multi-target posterior distribution. But there is no closed form solution to the PHD recursion. The Gaussian mixture probability hypothesis density
Achieving target voriconazole concentrations more accurately in children and adolescents.
Neely, Michael; Margol, Ashley; Fu, Xiaowei; van Guilder, Michael; Bayard, David; Schumitzky, Alan; Orbach, Regina; Liu, Siyu; Louie, Stan; Hope, William
2015-06-01
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
The role of wnt8 in posterior mesoderm formation
Kelton, Cathryn Renee
2009-05-15
in multiple vertebrate systems to perform two functions: to restrict the size of the dorsal mesoderm structure known as the organizer, and to promote the development of posterior mesoderm that populates the trunk and tail. Importantly, the organizer is a...
Abnormalities of fixation, saccade and pursuit in posterior cortical atrophy.
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
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.
A case of posterior scleritis: differential diagnosis of ocular pain
Ferdinando Maggioni; Silvia Ruffatti; Federica Viaro; Federico Mainardi; Carlo Lisotto; Giorgio Zanchin
2007-01-01
\\u000a Abstract\\u000a Posterior scleritis is a rare cause of ocular pain, due to scleral inflammation, presenting with periocular pain, pain on\\u000a movement and decreased vision. Although anterior scleritis may be associated with this condition, ocular signs may be absent.\\u000a We report a case of posterior scleritis, presenting with right-sided ocular and periocular pain, exacerbated by ocular movements,\\u000a irradiating to the ipsilateral
Posterior partially edentulous jaws, planning a rehabilitation with dental implants
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
Influence of persistent occiput posterior position on delivery outcome
Myra Fitzpatrick; Kathryn McQuillan; Colm O’Herlihy
2001-01-01
OBJECTIVE:To evaluate the influence of intrapartum persistent occiput posterior position of the fetal head on delivery outcome and anal sphincter injury, with reference to the association with epidural analgesia.METHODS:We conducted a prospective observational study of 246 women with persistent occiput posterior position in labor during a 2-year period, compared with 13,543 contemporaneous vaginal deliveries with occiput anterior position.RESULTS:The incidence of
Fatal intratumoral hemorrhage in posterior fossa tumors following ventriculoperitoneal shunt
R. Santhanam; Anandh Balasubramaniam; B. A. Chandramouli
2009-01-01
We report on two patients with rare major intratumoral hemorrhage following ventriculoperitoneal shunt in posterior fossa tumors. A 28-year-old woman with a midline posterior fossa lesion, whose imaging features suggested a fourth ventricular ependymoma with obstructive hydrocephalus, was subjected to a right ventriculoperitoneal shunt. Her consciousness deteriorated, and she experienced massive intratumoral hemorrhage and later died. An eight-year-old girl presented
7122013. Probability distributions and the normal distribution Probability distributions
Umble, Ron
1 7122013. Probability distributions and the normal distribution Probability distributions is a continuous random variable. o The probability distribution of a discrete random variable x distribution of x by filling in the frequency and probability that the discrete random variable assumes value
MAS5051 Probability and Probability Distributions Contents of Blocks
Jordan, Jonathan
MAS5051 Probability and Probability Distributions Contents of Blocks Block "Lectures" Topics A 1/2 1: Sample spaces and events 2: Defining probabilities B 3/4 3: Conditional probability 4 of linear combinations F 11/12 11: Bernoulli trials and the Binomial distribution 12: Binomial tables G 13
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
Superpositions of probability distributions.
Jizba, Petr; Kleinert, Hagen
2008-09-01
Probability distributions which can be obtained from superpositions of Gaussian distributions of different variances v=sigma;{2} play a favored role in quantum theory and financial markets. Such superpositions need not necessarily obey the Chapman-Kolmogorov semigroup relation for Markovian processes because they may introduce memory effects. We derive the general form of the smearing distributions in v which do not destroy the semigroup property. The smearing technique has two immediate applications. It permits simplifying the system of Kramers-Moyal equations for smeared and unsmeared conditional probabilities, and can be conveniently implemented in the path integral calculus. In many cases, the superposition of path integrals can be evaluated much easier than the initial path integral. Three simple examples are presented, and it is shown how the technique is extended to quantum mechanics. PMID:18851008
Big MACS: Accurate photometric calibration
NASA Astrophysics Data System (ADS)
Kelly, P. L.; von der Linden, A.; Applegate, D.; Allen, M.; Allen, S. W.; Burchat, P. R.; Burke, D. L.; Ebeling, H.; Capak, P.; Czoske, O.; Donovan, D.; Mantz, A.; Morris, R. G.
2012-08-01
Big MACS is a Python program that estimates an accurate photometric calibration from only an input catalog of stellar magnitudes and filter transmission functions. The user does not have to measure color terms which can be difficult to characterize. Supplied with filter transmission functions, Big MACS synthesizes an expected stellar locus for your data and then simultaneously solves for all unknown zeropoints when fitting to the instrumental locus. The code uses a spectroscopic model for the SDSS stellar locus in color-color space and filter functions to compute expected locus. The stellar locus model is corrected for Milky Way reddening. If SDSS or 2MASS photometry is available for stars in field, Big MACS can yield a highly accurate absolute calibration.
NSDL National Science Digital Library
Exner, Nicholas
This applet is designed to teach an application of probability. This Java applet works by simulating a situation where a three stage rocket is about to be launched. In order for a successful launch to occur all three stages of the rocket must successfully pass their pre-takeoff tests. By default, each stage has a 50% chance of success, however, this can be altered by dragging the bar next to each stage.
Probability and Information Theory
Gregory S. Chirikjian
This chapter serves as an introduction to concepts from elementary probability theory and information theory in the concrete\\u000a context of the real line and multi-dimensional Euclidean space. The probabilistic concepts of mean, variance, expected value,\\u000a marginalization, conditioning, and conditional expectation are reviewed. In this part of the presentation there is some overlap\\u000a with the previous chapter, which has some pedagogical
Quantum Probability Calculus as Fuzzy-Kolmogorovian Probability Calculus
NASA Astrophysics Data System (ADS)
Pykacz, Jaros?aw
2009-03-01
Representation of quantum logics by families of fuzzy sets allows to build fuzzy set-theoretic models of quantum probability spaces in a way fully analogous to the Kolmogorov construction of a classical probability space. Therefore, quantum probability calculus on the one hand may be seen as a special kind of fuzzy probability calculi, and on the other hand it proves to be more similar to the classical probability calculus than it is generally believed.
38 CFR 4.46 - Accurate measurement.
Code of Federal Regulations, 2013 CFR
2013-07-01
...Veterans' Relief DEPARTMENT OF VETERANS AFFAIRS SCHEDULE FOR RATING DISABILITIES Disability Ratings The Musculoskeletal System § 4.46 Accurate measurement. Accurate measurement of the length of stumps, excursion...
38 CFR 4.46 - Accurate measurement.
Code of Federal Regulations, 2011 CFR
2011-07-01
...Veterans' Relief DEPARTMENT OF VETERANS AFFAIRS SCHEDULE FOR RATING DISABILITIES Disability Ratings The Musculoskeletal System § 4.46 Accurate measurement. Accurate measurement of the length of stumps, excursion...
38 CFR 4.46 - Accurate measurement.
Code of Federal Regulations, 2014 CFR
2014-07-01
...Veterans' Relief DEPARTMENT OF VETERANS AFFAIRS SCHEDULE FOR RATING DISABILITIES Disability Ratings The Musculoskeletal System § 4.46 Accurate measurement. Accurate measurement of the length of stumps, excursion...
38 CFR 4.46 - Accurate measurement.
Code of Federal Regulations, 2012 CFR
2012-07-01
...Veterans' Relief DEPARTMENT OF VETERANS AFFAIRS SCHEDULE FOR RATING DISABILITIES Disability Ratings The Musculoskeletal System § 4.46 Accurate measurement. Accurate measurement of the length of stumps, excursion...
38 CFR 4.46 - Accurate measurement.
Code of Federal Regulations, 2010 CFR
2010-07-01
...Veterans' Relief DEPARTMENT OF VETERANS AFFAIRS SCHEDULE FOR RATING DISABILITIES Disability Ratings The Musculoskeletal System § 4.46 Accurate measurement. Accurate measurement of the length of stumps, excursion...
Document Ranking with Quantum Probabilities
Collings, Iain B.
Document Ranking with Quantum Probabilities Guido Zuccon School of Computing Science College for ranking documents. Quantum probability theory is used to estimate the probability of relevance of a document given a user's query. We posit that quantum probability theory can lead to a better estimation
Fast and accurate database searches with MS-GF+Percolator
Granholm, Viktor; Kim, Sangtae; Navarro, José C.F.; Sjölund, Erik; Smith, Richard D.; Käll, Lukas
2014-01-01
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 datasets. 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
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.
NSDL National Science Digital Library
2010-01-01
This lesson is designed to introduce students to the concept of chaos and how it relates to probability. The lesson briefly delves into the ideas of mean and variance as well. This lesson provides links to discussions and activities related to chaos as well as suggested ways to integrate them into the lesson. Finally, the lesson provides links to follow-up lessons designed for use in succession with the current one. Note, reading level is not indicated because the lesson does not include student reading material.
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.
How accurate is molecular dynamics?
Christian Bayer; Håkon Hoel; Petr Plechá?; Anders Szepessy; Raúl Tempone
2011-09-20
Born-Oppenheimer dynamics is shown to provide an accurate approximation of time-independent Schr\\"odinger observables for a molecular system with an electron spectral gap, in the limit of large ratio of nuclei and electron masses, without assuming that the nuclei are localized to vanishing domains. The derivation, based on a Hamiltonian system interpretation of the Schr\\"odinger equation and stability of the corresponding Hamilton-Jacobi equation, bypasses the usual separation of nuclei and electron wave functions, includes caustic states and gives a different perspective on the Born-Oppenheimer approximation, Schr\\"odinger Hamiltonian systems and numerical simulation in molecular dynamics modeling at constant energy microcanonical ensembles.
Symmetry, probability, and recognition in face space.
Sirovich, Lawrence; Meytlis, Marsha
2009-04-28
The essential midline symmetry of human faces is shown to play a key role in facial coding and recognition. This also has deep and important connections with recent explorations of the organization of primate cortex, as well as human psychophysical experiments. Evidence is presented that the dimension of face recognition space for human faces is dramatically lower than previous estimates. One result of the present development is the construction of a probability distribution in face space that produces an interesting and realistic range of (synthetic) faces. Another is a recognition algorithm that by reasonable criteria is nearly 100% accurate. PMID:19365075
Symmetry, probability, and recognition in face space
Sirovich, Lawrence; Meytlis, Marsha
2009-01-01
The essential midline symmetry of human faces is shown to play a key role in facial coding and recognition. This also has deep and important connections with recent explorations of the organization of primate cortex, as well as human psychophysical experiments. Evidence is presented that the dimension of face recognition space for human faces is dramatically lower than previous estimates. One result of the present development is the construction of a probability distribution in face space that produces an interesting and realistic range of (synthetic) faces. Another is a recognition algorithm that by reasonable criteria is nearly 100% accurate. PMID:19365075
Quantum Computation Based Probability Density Function Estimation
Balázs, F; Bal\\'azs, Ferenc
2004-01-01
Signal processing techniques will lean on blind methods in the near future, where no redundant, resource allocating information will be transmitted through the channel. To achieve a proper decision, however, it is essential to know at least the probability density function (pdf), which to estimate is classically a time consumption and/or less accurate hard task, that may make decisions to fail. This paper describes the design of a quantum assisted pdf estimation method also by an example, which promises to achieve the exact pdf by proper setting of parameters in a very fast way.
Quantum Computation Based Probability Density Function Estimation
Ferenc Balázs; Sándor Imre
2004-09-06
Signal processing techniques will lean on blind methods in the near future, where no redundant, resource allocating information will be transmitted through the channel. To achieve a proper decision, however, it is essential to know at least the probability density function (pdf), which to estimate is classically a time consumption and/or less accurate hard task, that may make decisions to fail. This paper describes the design of a quantum assisted pdf estimation method also by an example, which promises to achieve the exact pdf by proper setting of parameters in a very fast way.
Clinical simulation using context-sensitive temporal probability models.
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
External Dacryocystorhinostomy with and Without Suturing the Posterior Mucosal Flaps
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
Flexor Digitorum Accessorius Longus: Importance of Posterior Ankle Endoscopy
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.
A Simple Approach to Specimen Retrieval via Posterior Colpotomy Incision
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
Instrumented Posterior Lumbar Interbody Fusion in Adult Spondylolisthesis
Yu, Ching-Hsiao; Wang, Chen-Ti
2008-01-01
It is unclear whether using artificial cages increases fusion rates compared with use of bone chips alone in posterior lumbar interbody fusion for patients with lumbar spondylolisthesis. We hypothesized artificial cages for posterior lumbar interbody fusion would provide better clinical and radiographic outcomes than bone chips alone. We assumed solid fusion would provide good clinical outcomes. We clinically and radiographically followed 34 patients with spondylolisthesis having posterior lumbar interbody fusion with mixed autogenous and allogeneic bone chips alone and 42 patients having posterior lumbar interbody fusion with implantation of artificial cages packed with morselized bone graft. Patients with the artificial cage had better functional improvement in the Oswestry disability index than those with bone chips alone, whereas pain score, patient satisfaction, and fusion rate were similar in the two groups. Postoperative disc height ratio, slip ratio, and segmental lordosis all decreased at final followup in the patients with bone chips alone but remained unchanged in the artificial cage group. The functional outcome correlated with radiographic fusion status. We conclude artificial cages provide better functional outcomes and radiographic improvement than bone chips alone in posterior lumbar interbody fusion for lumbar spondylolisthesis, although both techniques achieved comparable fusion rates. Level of Evidence: Level III, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence. PMID:18846411
Tezer, Mehmet; Aydogan, Mehmet; Mirzanl?, Cunety; Ozturk, ?rfan
2010-01-01
We retrospectively studied the cases with tuberculous spondylitis of thoracolumbar region with two or more levels of involvement that underwent posterior instrumentation and fusion and anterior fusion with titanium mesh following anterior decompression using simultaneous successive posterior–anterior–posterior surgery. Among all patients with tuberculous spondylitis accompanied by medium or severe kyphosis, 20 patients who underwent simultaneous successive decompression, fusion and instrumentation with posterior–anterior–posterior surgery between 1999 and 2004 were included in the study. Patients were evaluated for fusion formation and neurological and functional status. Kyphosis angles were measured at early and long-term follow-up. Antituberculosis chemotherapy was initiated in all patients and continued for 9 months; initially as quadruple therapy for 3 months, and then as triple therapy. Average follow-up period was 52.7 months (range 37–94). Solid fusion was achieved in all patients. All patients returned to their previous occupation; 75% (15 subjects) with mild pain or no pain and 15% (3 subjects) with major limitations. There were 11 patients with neurological deficit, 9 of these achieved complete neurological recoveries. Regarding kyphosis angle, an average 35.1° correction (84.8%) was obtained in postoperative period (p < 0.001) and there was no significant correction loss during the follow-up period (p < 0.05). There were no grafts or instrumentation-related stabilization problems. In subjects with tuberculous spondylitis with involvements at two or more levels accompanied by medium and severe kyphosis, decompression, fusion and instrumentation by simultaneous successive posterior–anterior–posterior surgery is an effective and safe management method for effective kyphosis correction with high fusion rates. PMID:20589519
Supersymmetric probability distributions
S. Nicolis; A. Zerkak
2013-02-10
We use anticommuting variables to study probability distributions of random variables, that are solutions of Langevin's equation. We show that the probability density always enjoys "worldpoint supersymmetry". The partition function, however, may not. We find that the domain of integration can acquire a boundary, that implies that the auxiliary field has a non-zero expectation value, signalling spontaneous supersymmetry breaking. This is due to the presence of "fermionic" zeromodes, whose contribution cannot be cancelled by a surface term. This we prove by an explicit calculation of the regularized partition function, as well as by computing the moments of the auxiliary field and checking whether they satisfy the identities implied by Wick's theorem. Nevertheless, supersymmetry manifests itself in the identities that are satisfied by the moments of the scalar, whose expressions we can calculate,for all values of the coupling constant. We also provide some quantitative estimates concerning the visibility of supersymmetry breaking effects in the identities for the moments and remark that the shape of the distribution of the auxiliary field can influence quite strongly how easy it would be to mask them, since the expectation value of the auxiliary field doesn't coincide with its typical value.
Parameters for accurate genome alignment
2010-01-01
Background Genome sequence alignments form the basis of much research. Genome alignment depends on various mundane but critical choices, such as how to mask repeats and which score parameters to use. Surprisingly, there has been no large-scale assessment of these choices using real genomic data. Moreover, rigorous procedures to control the rate of spurious alignment have not been employed. Results We have assessed 495 combinations of score parameters for alignment of animal, plant, and fungal genomes. As our gold-standard of accuracy, we used genome alignments implied by multiple alignments of proteins and of structural RNAs. We found the HOXD scoring schemes underlying alignments in the UCSC genome database to be far from optimal, and suggest better parameters. Higher values of the X-drop parameter are not always better. E-values accurately indicate the rate of spurious alignment, but only if tandem repeats are masked in a non-standard way. Finally, we show that ?-centroid (probabilistic) alignment can find highly reliable subsets of aligned bases. Conclusions These results enable more accurate genome alignment, with reliability measures for local alignments and for individual aligned bases. This study was made possible by our new software, LAST, which can align vertebrate genomes in a few hours http://last.cbrc.jp/. PMID:20144198
The effect of posterior tibial slope on knee stability after Ortholoc total knee arthroplasty.
Whiteside, L A; Amador, D D
1988-01-01
The effect of posterior tibial slope was evaluated in a rotationally unconstrained anterior cruciate ligament-sacrificing total knee replacement (Ortholoc, Dow Corning Wright, Arlington, TN). Sloping the surface 7 degree posteriorly loosened the knee to varus-valgus and anterior-posterior stress in flexion. Eliminating posterior slope improved varus-valgus stability in flexion but slightly increased anterior-posterior laxity in extension. Values for the 3 degree posterior slope knee were between the values for 0 degree and 7 degree sloped surfaces, but not significantly different statistically from either. Total knee replacement designs with a posterior tibial slope are likely to promote anterior-posterior and varus-valgus laxity in flexion, and those with no posterior slope or 3 degree posterior slope are most likely to achieve normal stability in flexion and extension. PMID:3199140
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,
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.
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.
[Isolated posterior pre-marginal hernia. Apropos of 6 cases].
Siala, M; Bellamine, B; Abdelkafi, A; Hamza, R; Slimane, N; Chevrot, A
1988-10-01
Posterior pre-marginal disk hernia, a rare lesion, was diagnosed in six young adults with lumbago. Lateral lumbar spine radiographic images showed an unusual appearance, combining a posterior marginal defect of a vertebral corner and a small bony spicule projecting into lumbar canal. A literature review revealed 27 similar cases, mostly in adolescents. These vertebral disk anomalies are considered by some authors to be fractures of the posterior margin border. A more plausible hypothesis is a pre-marginal hernia, because of lack of a history of injury, the radiologic appearance comparable with that of sequelae of Scheuermann's disease, and the frequent association of these lesions with a spinal growth dystrophy. PMID:2974080
Giant cell arteritis: A rare cause of posterior vasculitis
Moschos, Marilita M; Guex-Crosier, Yan
2009-01-01
Purpose: To report three cases of posterior vasculitis associated with subacute giant cell arteritis (GCA). Methods: Three patients with decreased vision underwent complete ophthalmologic examination and fluorescein angiography. Results: All patients presented posterior vasculitis. Patient 1 had an erythrocyte sedimentation rate (ESR) of 38 mm/hr and a C-reactive protein (CRP) of 28mg/L. Patient 2 and 3 had an ESR of 104 and 95 mm/hr and a CRP of 42 and 195 mg/L accordingly. Diagnosis was established by temporal artery biopsy. Resolution was observed after systemic prednisolone therapy. Conclusion: GCA should be suspected when posterior vasculitis and relatively high ESR and CRP are present. PMID:19668553
Fatal intratumoral hemorrhage in posterior fossa tumors following ventriculoperitoneal shunt.
Santhanam, R; Balasubramaniam, Anandh; Chandramouli, B A
2009-01-01
We report on two patients with rare major intratumoral hemorrhage following ventriculoperitoneal shunt in posterior fossa tumors. A 28-year-old woman with a midline posterior fossa lesion, whose imaging features suggested a fourth ventricular ependymoma with obstructive hydrocephalus, was subjected to a right ventriculoperitoneal shunt. Her consciousness deteriorated, and she experienced massive intratumoral hemorrhage and later died. An eight-year-old girl presented with raised intracranial pressure and ataxia caused by vermian astrocytoma with obstructive hydrocephalus. She also developed a massive tumor bleed following a ventriculoperitoneal shunt and was subjected to emergency decompression of the tumor with the bleeding. She remained vegetative at discharge and died 18 months later. Intratumoral hemorrhage is a rare but important cause of morbidity and mortality in patients with posterior fossa tumors who undergo ventriculoperitoneal shunt. PMID:19013806
Bayesian image reconstruction with a hyperellipsoidal posterior in x-ray fiber diffraction
NASA Astrophysics Data System (ADS)
Baskaran, Shyamsunder; Millane, Rick P.
1998-09-01
The structure completion problem in x-ray fiber diffraction is addressed from a Bayesian perspective. The experimental data are sums of the squares of the amplitudes of particular sets of Fourier coefficients of the electron density. In addition, a part of the electron density. In addition, a part of the electron density is known. The image reconstruction problem is to estimate the missing part of the electron density. A Bayesian approach is taken in which the prior model for the image is based on the fact that it consists of atoms, i.e., the unknown electron density consists of separated sharp peaks. The posterior for the Fourier coefficients typically takes the form of an independent and identically distributed multivariate normal density restricted to the surface of a hypersphere. However, the electron density often exhibits symmetry, in which case, the Fourier coefficient components are not longer independent or identically distributed. A diagonalization process results in an independent multivariate normal probability density function, restricted to a hyperspherical surface. the analytical form for the mean of the posterior density function is derived. The mean can be expressed as a weighting function on the Fourier coefficients of the known part of the electron density. The weighting function for the hyperellipsoidal and hyperspherical cases are compared.
Accurate DS-CDMA bit-error probability calculation in Rayleigh fading
Julian Cheng; Norman C. Beaulieu
2002-01-01
A binary direct-sequence spread-spectrum multiple-access system with random sequences in flat Rayleigh fading is considered. A new explicit closed-form expression is obtained for the characteristic function of the multiple-access interference signals. It is shown that the overall error rate can be expressed by a single integral whose integrand is nonnegative and exponentially decaying. Bit-error rates (BERs) are obtained with this
van Eeden, Fredericus J.M.; Palacios, Isabel M.; Petronczki, Mark; Weston, Matthew J.D.; St Johnston, Daniel
2001-01-01
The localization of Oskar at the posterior pole of the Drosophila oocyte induces the assembly of the pole plasm and therefore defines where the abdomen and germ cells form in the embryo. This localization is achieved by the targeting of oskar mRNA to the posterior and the localized activation of its translation. oskar mRNA seems likely to be actively transported along microtubules, since its localization requires both an intact microtubule cytoskeleton and the plus end–directed motor kinesin I, but nothing is known about how the RNA is coupled to the motor. Here, we describe barentsz, a novel gene required for the localization of oskar mRNA. In contrast to all other mutations that disrupt this process, barentsz-null mutants completely block the posterior localization of oskar mRNA without affecting bicoid and gurken mRNA localization, the organization of the microtubules, or subsequent steps in pole plasm assembly. Surprisingly, most mutant embryos still form an abdomen, indicating that oskar mRNA localization is partially redundant with the translational control. Barentsz protein colocalizes to the posterior with oskar mRNA, and this localization is oskar mRNA dependent. Thus, Barentsz is essential for the posterior localization of oskar mRNA and behaves as a specific component of the oskar RNA transport complex. PMID:11481346
Morphologic study of posterior articular depression in Schatzker IV fractures.
Zhai, Qilin; Hu, Chengfang; Xu, Yafeng; Wang, Dan; Luo, Congfeng
2015-02-01
The Schatzker classification of tibial plateau fractures is widely accepted. Type IV fractures are medial tibial plateau fractures that are either split off as a wedge fragment or depressed and comminuted. Posterior articular surface depression in Schatzker type IV tibial plateau fractures can be seen as a unique variant that increases the difficulty of reduction of the articular surface. Its morphologic characteristics have not been fully studied, and the incidence is sometimes underestimated. The goal of this study was to evaluate the morphologic characteristics of posterior articular depression in Schatzker type IV fractures based on computed tomography measurements. From January 2009 to December 2011, the medical records, including digital radiologic data, of all patients treated for tibial plateau fracture at the authors' institution were retrospectively analyzed. Articular surface depression deeper than 5 mm was the criterion for study inclusion. The depression depth, precise location of the articular depression center, surface area percentage, and distance of the fracture gap to the depression center were calculated. One hundred fifteen cases of Schatzker type IV fracture were retrieved, and a total of 47.83% (55 of 115) cases had posterior articular surface depression. The average depth of the depressed articular surface was 12.41 mm, the surface area percentage was 20.15% of the entire tibial plateau, and the gap distance from the medial direction was 41.40 mm, 2.8 times longer than that from the posterior direction, which was 14.91 mm. Posterior articular surface depression occurs in nearly half of Schatzker type IV fractures, and the posterior approach provides more direct access to the depression than the medial approach. PMID:25665117
The laparoscopic fundoplications: Nissen and partial posterior (Toupet) fundoplication
H. Wykypiel; H. Bonatti; R. A. Hinder; K. Glaser; G. J. Wetscher
2006-01-01
\\u000a Zusammenfassung GRUNDLAGEN: Die gastroösophageale Refluxkrankheit ist weit verbreitet und kann mit einer laparoskopischen Fundoplikation kausal\\u000a behandelt werden. Die Nissen-Fundoplikation und die partielle posteriore Fundoplikation (nach Toupet) sind die gängigsten\\u000a Operationen. METHODIK: Detaillierte Beschreibung der Operationstechnik und der Ergebnisse mit Übersicht über die Literatur.\\u000a ERGEBNISSE: Die Nissen- und die partielle posteriore Fundoplikation können GERD-Symptome heilen und die Lebensqualität verbessern,\\u000a sie können eine
Posterior tibial tendon dysfunction in the adult: current concepts.
Stein, Benjamin E; Schon, Lew C
2015-01-01
The management of posterior tibial tendon dysfunction in adults has evolved substantially, and controversy persists regarding a specific recommended algorithm for treatment. The current focus is on early diagnosis and treatment of this disorder with joint-sparing surgeries, such as corrective osteotomies and tendon transfers, when nonsurgical modalities have been exhausted. It is helpful to be familiar with the pertinent pathophysiology and diagnostic pearls associated with posterior tibial tendon dysfunction, its treatment options, pertinent literature, and technique tips for the procedures currently being used. PMID:25745927
Posterior Reversible Encephalopathy Syndrome Presenting as Opsoclonus-Myoclonus
Boland, Torrey; Strause, Jamie; Hu, Myra; Santamaria, Dolores; Liang, Tsao-Wei; Kremens, Daniel; Sergott, Robert; Moussouttas, Michael
2012-01-01
Opsoclonus-myoclonus may be caused by various neurological conditions and toxic-metabolic states, but typically occurs as a parainfectious or paraneoplastic manifestation. The development of opsoclonus-myo-clonus has been variably attributed to lesions in the pons or cerebellum. Herein the authors describe a case of opsoclonus-myoclonus due to posterior reversible encephalopathy syndrome in which magnetic resonance imaging revealed lesions in the region of the cerebellar dentate nuclei. Clinical and radiological resolution of the opsoclonus-myoclonus and of the posterior reversible encephalopathy syndrome followed antihyperten-sive therapy. PMID:23125471
Posterior tibial vein aneurysm presenting as tarsal tunnel syndrome.
Ayad, Micheal; Whisenhunt, Anumeha; Hong, EnYaw; Heller, Josh; Salvatore, Dawn; Abai, Babak; DiMuzio, Paul J
2015-06-01
Tarsal tunnel syndrome is a compressive neuropathy of the posterior tibial nerve within the tarsal tunnel. Its etiology varies, including space occupying lesions, trauma, inflammation, anatomic deformity, iatrogenic injury, and idiopathic and systemic causes. Herein, we describe a 46-year-old man who presented with left foot pain. Work up revealed a venous aneurysm impinging on the posterior tibial nerve. Following resection of the aneurysm and lysis of the nerve, his symptoms were alleviated. Review of the literature reveals an association between venous disease and tarsal tunnel syndrome; however, this report represents the first case of venous aneurysm causing symptomatic compression of the nerve. PMID:25199522
Rare posterior reversible encephalopathy syndrome in a patient with HIV.
Ribeiro, Sofia; Monteiro, Marta; Moreira, Bruno; França, Margarida
2013-01-01
Posterior reversible encephalopathy syndrome (PRES) is an uncommon neurological disorder, characterised by the rapid onset of neurological deficits and characteristic neuroimaging findings-cerebral oedema with a typical preference for the posterior white matter. We report a case of a 59-year-old woman with an untreated HIV infection and hypertension with a PRES diagnosis and a rare involvement of the basal ganglia and brainstem, with microhemorrhages. HIV infection, particularly if untreated, is associated with an inflammatory status and therefore endothelial damage and dysfunction that might have an important role in predisposing acute hypertensive crisis and PRES. PMID:24252840
Accurate extraction of the News
Shrirang S. Deshingkar
2006-09-14
We propose a new scheme for extracting gravitational radiation from a characteristic numerical simulation of a spacetime. This method is similar in conception to our earlier work but analytical and numerical implementation is different. The scheme is based on direct transformation to the Bondi coordinates and the gravitational waves are extracted by calculating the Bondi news function in Bondi coordinates. The entire calculation is done in a way which will make the implementation easy when we use uniform Bondi angular grid at $\\mathcal I^+$. Using uniform Bondi grid for news calculation has added advantage that we have to solve only ordinary differential equations instead of partial differential equation. For the test problems this new scheme allows us to extract gravitational radiation much more accurately than the previous schemes.
Accurate and superaccurate gene mapping.
Lange, K; Kunkel, L; Aldridge, J; Latt, S A
1985-01-01
Highly accurate gene mapping techniques need to be developed to clone disease genes with unknown defective products. The classical pedigree method and methods based on cytologically observable chromosome aberrations share definite limits in resolution. We quantify the limits in resolution for the pedigree method. We also discuss a technique for gene localization that exploits the possible presence of minute depletions overlapping the disease locus. One can search for such submicroscopic deletions by aiming random probes at them. We show quantitatively that relatively few probes may suffice to hit a target deletion. Choosing which probes to aim should be guided by pedigree studies and by close examination of relevant cytologically observable translocations and deletions. PMID:2931976
Gorczyca, J; Skawina, A; Litwin, J A; Miodo?ski, A J
1998-02-01
The vasculature of lumbar posterior root ganglia was investigated in human fetuses aged 17-24 weeks; using the corrosion casting technique and scanning electron microscopy. The arterial supply consisted of one main artery and occasional arterioles entering the ganglion at its pole and running axially, while the venous drainage was located at the periphery of the ganglion, thus indicating a centrifugal pattern of blood flow. The dense capillary network of the ganglion showed the roughly parallel course of the vessels in the central zone and an irregular arrangement in the peripheral zone where capillaries formed "nests", probably surrounding individual perikaryons of ganglionic cells. The capillaries had a sinusoidal character with numerous dilatations about twice the normal capillary size, as well as occasional larger vascular spaces resulting from capillary interconnections and suggesting the intussusceptive type of angiogenesis. PMID:9488902
Pippi — Painless parsing, post-processing and plotting of posterior and likelihood samples
NASA Astrophysics Data System (ADS)
Scott, Pat
2012-11-01
Interpreting samples from likelihood or posterior probability density functions is rarely as straightforward as it seems it should be. Producing publication-quality graphics of these distributions is often similarly painful. In this short note I describe pippi, a simple, publicly available package for parsing and post-processing such samples, as well as generating high-quality PDF graphics of the results. Pippi is easily and extensively configurable and customisable, both in its options for parsing and post-processing samples, and in the visual aspects of the figures it produces. I illustrate some of these using an existing supersymmetric global fit, performed in the context of a gamma-ray search for dark matter. Pippi can be downloaded and followed at http://github.com/patscott/pippi.
Bladder augmentation and continent urinary diversion in boys with posterior urethral valves.
Baka-Ostrowska, Ma?gorzata
2011-01-01
Posterior urethral valve (PUV) is a condition that leads to characteristic changes in the bladder and upper urinary tract. Dysfunction of the bladder such as a hyperreflective, hypertonic, and small capacity bladder as well as sphincter incompetence and/or myogenic failure should be adequately treated. Poor compliance/small bladder could be treated with anticholinergics, but bladder augmentation will probably be indicated. Although bladder reconstruction with gastrointestinal segments can be associated with multiple complications, including metabolic disorders, calculus formation, mucus production, enteric fistulas, and malignancy formation, enterocystoplasty is still the gold standard. In contrast to a neuropathic or exstrophic bladder, augmentation of the valve bladder allows spontaneous voiding without significant residual urine in the majority of cases, but some require CIC (clean intermittent cathterization). Augmentation cystoplasty is also an efficient approach in those children who will require kidney transplantation in the future. PMID:24578902
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.
Parametric probability distributions in reliability
Coolen, Frank
Parametric probability distributions in reliability F.P.A. Coolen Department of Mathematical parametric probability distributions which are frequently used in reliability. We present some main as models for specific reliability scenarios. Keywords: Binomial distribution, Exponential distribution
Long-term occurrence probabilities of intense geomagnetic storm events
K. Tsubouchi; Y. Omura
2007-01-01
A quantitative assessment of the occurrence probability of intense geomagnetic storms (peak Dst 280 nT) storms. The mathematical tool to determine this type of PDF is the extreme value modeling, which exhibits more accurate statistics for extreme behavior. Our results estimate S60 ? 589, indicating that the March 1989 storm (the event with the largest ?Dst? in the database) corresponds
Discrete Approximations of Probability Distributions
Allen C. Miller III; Thomas R. Rice
1983-01-01
Practical limits on the size of most probabilistic models require that probability distributions be approximated by a few representative values and associated probabilities. This paper demonstrates that methods commonly used to determine discrete approximations of probability distributions systematically underestimate the moments of the original distribution. A new procedure based on gaussian quadrature is developed in this paper. It can be
Accurate models for EUV lithography
NASA Astrophysics Data System (ADS)
Hendrickx, Eric; Lorusso, Gian F.; Jiang, Jiong; Chen, Luoqi; Liu, Wei; Van Setten, Eelco; Hansen, Steve
2009-10-01
Accurate modeling of EUV Lithography is a mandatory step in driving the technology towards its foreseen insertion point for 22-16nm node patterning. The models are needed to correct EUV designs for imaging effects, and to understand and improve the CD fingerprint of the exposure tools. With a full-field EUV ADT from ASML now available in the IMEC cleanroom, wafer data can be collected to calibrate accurate models and check if the existing modeling infrastructure can be extended to EUV lithography. As a first topic, we have measured the CD on wafer of a typical OPC dataset at different flare levels and modeled the evolution of wafer CD through flare, reticle CD, and pitch using Brion's Tachyon OPC engine. The modeling first requires the generation of a flare map using long-range kernels to model the EUV specific long-range flare. The accuracy of the flare map can be established independently from the CD measurements, by using the traditional disappearing pad test for flare determination (Kirk test). The flare map is then used as background intensity in the calibration of the traditional optical models with short-range kernels. For a structure set of 600 features and over a flare range of 4-6%, an rms fit value of 0.9nm was obtained. As a second aspect of the modeling, we have calibrated a full resist model to process window data. The full resist model is then used in a combination with experimental measurements of reticle CD, slit intensity uniformity, focal plane behavior, and EUV thick mask effects to model the evolution of wafer CD across the exposure field. The modeled evolution of CD across the exposure field was found to be a good match to the experimentally seen evolution of CD across the field, and confirms that the 4 factors mentioned above are main contributions to the CD uniformity across the field. As such the modeling work enables a better understanding of the errors contributing to CD variation across the field for EUV technology.
Seismic Hazard Assessment: Conditional Probability
NSDL National Science Digital Library
Nicholas Pinter
In this exercise, students investigate the use of conditional probability (the likelihood that a given event will occur within a specified time period) in assessing earthquake hazards. Introductory materials explain that conditional probability is based on the past history of earthquakes in a region and on how and when earthquakes recur; and discuss the different types of models that can be developed to predict recurrences. Using a table of probability values, students will calculate probabilities for earthquakes along the San Andreas and Wasatch Fault zones, and calculate probabilities that they will exceed a given acceleration (ground shaking) value. Example problems and a bibliography are provided.
Posterior consistency of logistic Gaussian process priors in density estimation
Surya T. Tokdar; Jayanta K. Ghosh
2007-01-01
We establish weak and strong posterior consistency of Gaussian process priors studied by Lenk [1988. The logistic normal distribution for Bayesian, nonparametric, predictive densities. J. Amer. Statist. Assoc. 83 (402), 509–516] for density estimation. Weak consistency is related to the support of a Gaussian process in the sup-norm topology which is explicitly identified for many covariance kernels. In fact we
Multisensor resource deployment using posterior Cramer-Rao bounds
MARCEL L. HERNANDEZ; THIA KIRUBARAJAN; YAAKOV BAR-SHALOM
2004-01-01
The development of a general framework for the systematic management of multiple sensors in target tracking in the presence of clutter is described. The basis of the technique is to quantify, and subsequently control, the accuracy of target state estimation. The posterior Cramer-Rao lower bound (PCRLB) provides the means of achieving this aim by enabling us to determine a bound
Natural history and nonoperative treatment of posterior cruciate ligament injuries
Sanjiv Jari; K. Donald Shelbourne
2001-01-01
The posterior cruciate ligament (PCL) is a major stabilizer of the knee. It is a structure that can be injured both inhigh-energy situations (eg, road traffic accidents) and in low-energy environments such as sporting injuries. The PCL can be torn in isolation or in combination with other knee structures \\/ligaments with the mechanism of injury determining the structures damaged. The
Posterior choroidal leiomyoma: a rare case report and literature review.
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
Urethral strictures after fulguration of posterior urethral valves
Richa Lal; V Bhatnagar; D. K Mitra
1998-01-01
This report discusses the incidence and predisposing factors for postfulguration urethral strictures in 82 boys with posterior urethral valves treated over 20 years and followed up for a period ranging from 1 to 21 years. A urethral stricture developed in three of the 82 patients (3.6%). All newborns and infants with small urethral caliber at presentation were treated on a
Percutaneous fetal cystoscopy and endoscopic fulguration of posterior urethral valves
Rubén A. Quintero; Roderick Hume; Craig Msith; Mark P. Johnson; David B. Cotton; Roberto Romero; Mark I. Evans
1995-01-01
Percutaneous fetal cystoscopy was performed in a male fetus with ultrasonographic evidence of lower urinary tract obstruction at 19 weeks of gestation. The diagnosis of posterior urethral valves was confirmed. Percutaneous endoscopic fulguration of the valves was successfully performed at 22 weeks of gestation, and urethral patency was established. This case illustrates the feasibility of performing diagnostic and therapeutic endoscopic
Successful Renal Transplantation in Children With Posterior Urethral Valves
WILLIAM DeFOOR; LESLIE TACKETT; EUGENE MINEVICH; PAUL McENERY; DAVID KITCHENS; DEBORAH REEVES; CURTIS SHELDON
2003-01-01
PurposeThe treatment of children with posterior urethral valve (PUV) and end-stage renal disease can be challenging. Some series have had poor outcomes after renal transplantation with an increased risk of graft dysfunction and urinary tract infections. We present our experience with a pediatric population and compare it to all the other pediatric renal transplants done at our institution.
Neonatal rupture of the bladder secondary to posterior urethral valves
L. Johanson
1982-01-01
Rupture of the neonatal urinary bladder during pregnancy or delivery is an extremely rare event, in some patients seondary to posterior urethral valves. In a recent case early diagnosis facilitated prompt surgical repair. A temporary bladder fistula secured survival and micturition cystourethrography establishment of the valves, which were successfully resected at two weeks of age.
Initial and long-term management of posterior urethral valves
P. López Pereira; M. J. Martinez Urrutia; E. Jaureguizar
2004-01-01
Posterior urethral valves are the most common cause of congenital obstructive uropathy, resulting in renal failure in childhood. Nowadays, in most cases, diagnosis is suggested by antenatal ultrasound. However, antenatal intervention has not resulted in a significantly improved outcome. Endoscopic valve ablation is the initial treatment in most of these neonates, but others procedures, like vesicostomy or ureterostomy, can also
Augmentation Cystoplasty in Boys with Posterior Urethral Valves
A. M. Kajbafzadeh; F. M. J. Quinn; P. G. Duffy; P. G. Ransley
1995-01-01
The role of augmentation cystoplasty in the neuropathic and exstrophy bladder has been well documented. However, its place and the timing of such surgery in the “valve bladder” are not well established. We report our experience with augmentation cystoplasty in 20 boys with previously treated posterior urethral valves. Urodynamic studies confirmed poorly compliant, unstable bladders with low functional capacities, which
Incomplete hypospadiac urethral duplication with posterior urethral valves
T. M. Ramanujam; A. Sergius; V. Usha; S. Ramanathan
1998-01-01
Urethral duplication (UD) is an uncommon malformation. Obstruction rarely occurs in hypospadiac UD. We describe two children\\u000a with incomplete hypospadiac UD in association with posterior urethral valves, a combination not previously recognised. The\\u000a embryonic significance of this anomaly is discussed.
Fetoscopic Transuterine Release of Posterior Urethral Valves: A New Technique
Matthew S. Clifton; Michael R. Harrison; Robert Ball; Hanmin Lee
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
Posterior Urethral Valves, Pressure Pop-offs and Bladder Function
Martin Kaefer; Mark C. Adams; Richard C. Rink
1995-01-01
The pop-off mechanisms that sometimes occur with posterior urethral valves have well recognized implications for renal function, such that 1 or both kidneys can be protected from the deleterious effects of elevated bladder pressures. What has not been defined is the significance, if any, of pressure pop-offs to the developing bladder and ultimate bladder function. To answer this question we
Pre and postoperative urographic findings in posterior urethral valves
O. Eklöf; H. Ringertz
1975-01-01
In a series of 65 male infants and children, all with the diagnosis of posterior urethral valves, pre- and postoperative urographic findings were reviewed. In addition changes occurring in the bladder, and the implication of vesico-ureteral reflux were assessed. — Preoperatively diagnosed impairment of kidney function and concommitant dilatation of the upper urinary tract, with some exceptions, remained fairly unchanged
Superdominant Right Coronary Artery with Double Posterior Descending Artery
Maheshwari, Monika; Mittal, S. R.
2015-01-01
Coronary artery anomalies are rare entities. All angiographers and cardiac surgeons need to be familiar with these anatomic variants for proper surgical revasularisation in the presence of coronary artery disease. We report here an interesting case of superdominant right coronary artery with double posterior descending artery. PMID:25838874
Cataract progression and treatment following posterior lamellar keratoplasty
Marianne O Price; Francis W Price
2004-01-01
Purpose: To describe the development and treatment of cataracts following posterior lamellar keratoplasty (PLK) in phakic eyes with Fuchs' endothelial dystrophy.Setting: Price Vision Group, Indianapolis, Indiana, USA.Methods: A retrospective chart review was performed on 47 PLK cases performed by a single surgeon between June 2001 and December 2002 in a tertiary care setting. Four of the eyes were phakic at
Resin-modified glass ionomers for luting posterior ceramic restorations
Birger Thonemann; Marianne Federlin; Gottfried Schmalz; Karl-Anton Hiller
1995-01-01
Objectives. Until recently, esthetic inlay restorations in posterior teeth have been limited to cavities surrounded by enamel. Dentin adhesive systems in combination with luting composites and light-cured resin-modified glass ionomer cements offer a possibility for bonding ceramic inlays to cavities when the cervical margin is in dentin. This study was designed to compare in vitro marginal integrity of ceramic inlays
Posterior cruciate ligament reconstruction using an arthroscopic femoral inlay technique.
Margheritini, Fabrizio; Frascari Diotallevi, Francesco; Mariani, Pier Paolo
2011-12-01
Several techniques for posterior cruciate ligament reconstruction have been developed. The purpose of this paper is to present a new surgical technique that provides greater anatomical femoral fixation avoiding the sharp angle made by the graft at the exit of the femoral tunnel. PMID:21409466
Covering Your Posterior: Teaching Signaling Games Using Classroom Experiments
ERIC Educational Resources Information Center
Turocy, Theodore L.
2009-01-01
The author describes a protocol for classroom experiments for courses that introduce undergraduates to signaling games. Signaling games are conceptually difficult because, when analyzing the game, students are not naturally inclined to think in probabilistic, Bayesian terms. The experimental design explicitly presents the posterior frequencies of…
Minimally invasive posterior stabilization for treating spinal tuberculosis.
Rigotti, S; Boriani, L; Luzi, C A; Marocco, S; Angheben, A; Gasbarrini, A; Zorzi, C
2013-06-01
We describe a case of dorsal-lumbar vertebral tuberculosis (Pott's disease) first treated with antibiotic therapy, bed rest, and cast. After 2 months of treatment patient's symptoms worsened. Minimally invasive posterior vertebral stabilization was carried out, with excellent clinic and radiographic results. PMID:22358780
Distinguishing torpedo maculopathy from similar lesions of the posterior segment.
Villegas, Victor M; Schwartz, Stephen G; Flynn, Harry W; Capó, Hilda; Berrocal, Audina M; Murray, Timothy G; Harbour, J William
2014-01-01
Torpedo maculopathy is a congenital solitary, oval-shaped lesion typically located temporal to the center of the macula. Congenital hypertrophy of the retinal pigment epithelium (RPE), RPE lesions of Gardner syndrome, and other lesions can present with similar characteristics. Because of its unique clinical and imaging features, torpedo maculopathy generally can be differentiated from other posterior segment lesions. PMID:24738480
Blood Vessels of the Fetal Pig Dissection Posterior Vessels Protocol
Loughry, Jim
Blood Vessels of the Fetal Pig Dissection Posterior Vessels Protocol: 1. The blood vessels membrane is the peritoneum, the blood vessels are said to be retroperitoneal). In order to see the blood that supplies the stomach, liver and spleen with blood. This is the celiac artery. c. Just below where
Posterior dislocation of the hip while playing basketball
T. D. Tennent; A. F. Chambler; D. J. Rossouw
1998-01-01
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
Arthroscopic Subtalar Arthrodesis: The Posterior Approach in the Prone Position
Luis Perez Carro; Pau Golanó; Jordi Vega
2007-01-01
Arthroscopic subtalar arthrodesis, as reported by Tasto, is done in the lateral decubitus position, and the portal sites are lateral. This report describes a new alternative method in which the patient is in the prone position and a posterior 2-portal approach is used, as described by van Dijk et al. The initial debridement and synovectomy are performed with 4- and
Oracle posterior rates in the White Noise Model
A. Babenko
2010-01-01
All the results about posterior rates obtained until now are related to the optimal (minimax) rates for the estimation problem over the corresponding nonparametric smoothness classes, i.e. of a global nature. In the meantime, a new local approach to optimality has been developed within the estimation framework, namely, the oracle approach. The main goal of this thesis is to develop
The posterior hypothalamic area: chemoarchitecture and afferent connections
Eric E. Abrahamson; Robert Y. Moore
2001-01-01
This study provides an analysis of the chemoarchitecture of the posterior hypothalamic area (PHA) and a retrograde transport analysis of inputs to the PHA in the rat. The chemoarchitectural analysis reveals that the majority of PHA neurons contain glutamate. Hypocretin, melanin concentrating hormone, tyrosine hydroxylase, neuropeptide Y and ?-aminobutyric acid are also found in subsets of PHA neurons, and fibers
Posterior cruciate ligament injuries in trauma patients: Part II
Gregory C. Fanelli; Craig J. Edson
1995-01-01
The purpose of this article is to present the incidence of posterior cruciate ligament (PCL) injuries in trauma patients with acute hemarthrosis of the knee. There were 222 acute knee injuries with hemarthrosis presented to our regional trauma center over a 38-month period. PCL injuries occurred in 38% (85 of 222) acute knee injuries; 56.5% (48 of 85) were trauma
Probability state modeling theory.
Bagwell, C Bruce; Hunsberger, Benjamin C; Herbert, Donald J; Munson, Mark E; Hill, Beth L; Bray, Chris M; Preffer, Frederic I
2015-07-01
As the technology of cytometry matures, there is mounting pressure to address two major issues with data analyses. The first issue is to develop new analysis methods for high-dimensional data that can directly reveal and quantify important characteristics associated with complex cellular biology. The other issue is to replace subjective and inaccurate gating with automated methods that objectively define subpopulations and account for population overlap due to measurement uncertainty. Probability state modeling (PSM) is a technique that addresses both of these issues. The theory and important algorithms associated with PSM are presented along with simple examples and general strategies for autonomous analyses. PSM is leveraged to better understand B-cell ontogeny in bone marrow in a companion Cytometry Part B manuscript. Three short relevant videos are available in the online supporting information for both of these papers. PSM avoids the dimensionality barrier normally associated with high-dimensionality modeling by using broadened quantile functions instead of frequency functions to represent the modulation of cellular epitopes as cells differentiate. Since modeling programs ultimately minimize or maximize one or more objective functions, they are particularly amenable to automation and, therefore, represent a viable alternative to subjective and inaccurate gating approaches. © 2015 International Society for Advancement of Cytometry. PMID:26012929
Repetition probability effects for inverted faces.
Grotheer, Mareike; Hermann, Petra; Vidnyánszky, Zoltán; Kovács, Gyula
2014-11-15
It has been shown, that the repetition related reduction of the blood-oxygen level dependent (BOLD) signal is modulated by the probability of repetitions (P(rep)) for faces (Summerfield et al., 2008), providing support for the predictive coding (PC) model of visual perception (Rao and Ballard, 1999). However, the stage of face processing where repetition suppression (RS) is modulated by P(rep) is still unclear. Face inversion is known to interrupt higher level configural/holistic face processing steps and if modulation of RS by P(rep) takes place at these stages of face processing, P(rep) effects are expected to be reduced for inverted when compared to upright faces. Therefore, here we aimed at investigating whether P(rep) effects on RS observed for face stimuli originate at the higher-level configural/holistic stages of face processing by comparing these effects for upright and inverted faces. Similarly to previous studies, we manipulated P(rep) for pairs of stimuli in individual blocks of fMRI recordings. This manipulation significantly influenced repetition suppression in the posterior FFA, the OFA and the LO, independently of stimulus orientation. Our results thus reveal that RS in the ventral visual stream is modulated by P(rep) even in the case of face inversion and hence strongly compromised configural/holistic face processing. An additional whole-brain analysis could not identify any areas where the modulatory effect of probability was orientation specific either. These findings imply that P(rep) effects on RS might originate from the earlier stages of face processing. PMID:25123974
Parks, John W.
2010-01-01
Previously we showed that weekly, written, timed, and peer-graded practice exams help increase student performance on written exams and decrease failure rates in an introductory biology course. Here we analyze the accuracy of peer grading, based on a comparison of student scores to those assigned by a professional grader. When students graded practice exams by themselves, they were significantly easier graders than a professional; overall, students awarded ?25% more points than the professional did. This difference represented ?1.33 points on a 10-point exercise, or 0.27 points on each of the five 2-point questions posed. When students graded practice exams as a group of four, the same student-expert difference occurred. The student-professional gap was wider for questions that demanded higher-order versus lower-order cognitive skills. Thus, students not only have a harder time answering questions on the upper levels of Bloom's taxonomy, they have a harder time grading them. Our results suggest that peer grading may be accurate enough for low-risk assessments in introductory biology. Peer grading can help relieve the burden on instructional staff posed by grading written answers—making it possible to add practice opportunities that increase student performance on actual exams. PMID:21123695
A More Accurate Fourier Transform
Courtney, Elya
2015-01-01
Fourier transform methods are used to analyze functions and data sets to provide frequencies, amplitudes, and phases of underlying oscillatory components. Fast Fourier transform (FFT) methods offer speed advantages over evaluation of explicit integrals (EI) that define Fourier transforms. This paper compares frequency, amplitude, and phase accuracy of the two methods for well resolved peaks over a wide array of data sets including cosine series with and without random noise and a variety of physical data sets, including atmospheric $\\mathrm{CO_2}$ concentrations, tides, temperatures, sound waveforms, and atomic spectra. The FFT uses MIT's FFTW3 library. The EI method uses the rectangle method to compute the areas under the curve via complex math. Results support the hypothesis that EI methods are more accurate than FFT methods. Errors range from 5 to 10 times higher when determining peak frequency by FFT, 1.4 to 60 times higher for peak amplitude, and 6 to 10 times higher for phase under a peak. The ability t...
Clinical, FDG and amyloid PET imaging in posterior cortical atrophy.
Singh, Tarun D; Josephs, Keith A; Machulda, Mary M; Drubach, Daniel A; Apostolova, Liana G; Lowe, Val J; Whitwell, Jennifer L
2015-06-01
The purpose of this study was to identify the clinical, [(18)F]-fluorodeoxyglucose positron emission tomography (FDG-PET) and amyloid-PET findings in a large cohort of posterior cortical atrophy (PCA) patients, to examine the neural correlates of the classic features of PCA, and to better understand the features associated with early PCA. We prospectively recruited 25 patients who presented to the Mayo Clinic between March 2013 and August 2014 and met diagnostic criteria for PCA. All patients underwent a standardized set of tests and amyloid imaging with [(11)C] Pittsburg compound B (PiB). Seventeen (68 %) underwent FDG-PET scanning. We divided the cohort at the median disease duration of 4 years in order to assess clinical and FDG-PET correlates of early PCA (n = 13). The most common clinical features were simultanagnosia (92 %), dysgraphia (68 %), poly-mini-myoclonus (64 %) and oculomotor apraxia (56.5 %). On FDG-PET, hypometabolism was observed bilaterally in the lateral and medial parietal and occipital lobes. Simultanagnosia was associated with hypometabolism in the right occipital lobe and posterior cingulum, optic ataxia with hypometabolism in left occipital lobe, and oculomotor apraxia with hypometabolism in the left parietal lobe and posterior cingulate gyrus. All 25 PCA patients were amyloid positive. Simultanagnosia was the only feature present in 85 % of early PCA patients. The syndrome of PCA is associated with posterior hemisphere hypometabolism and with amyloid deposition. Many of the classic features of PCA show associated focal, but not widespread, areas of involvement of these posterior hemispheric regions. Simultanagnosia appears to be the most common and hence sensitive feature of early PCA. PMID:25862483
Izadparast, Amir Hossein
2012-02-14
In this study, the semi-empirical approach is introduced to accurately estimate the probability distribution of complex non-linear random variables in the field of wavestructure interaction. The structural form of the semi-empirical distribution...
The relationship between species detection probability and local extinction probability
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.
OUTCOME OF POSTERIOR URETHRAL VALVES: TO WHAT EXTENT IS IT IMPROVED BY PRENATAL DIAGNOSIS?
ALAA EL-GHONEIMI; ARNAUD DESGRIPPES; DOMINIQUE LUTON; MARIE-ALICE MACHER; JEAN GUIBOURDENCHE; CATHERINE GAREL; FRANCOISE MULLER; EDITH VUILLARD; HENRI LOTTMANN; CATHERINE NESSMANN; JEAN-FRANCOIS OURY; YVES AIGRAIN
1999-01-01
PurposeTo assess the impact of prenatal diagnosis and evaluation on the outcome of posterior urethral valves we studied all cases of valves detected prenatally, including cases of pregnancy termination due to posterior urethral valves.
Primary pleural epithelioid hemangioendothelioma mimicking as a posterior mediastinal tumor
Wethasinghe, James; Sood, Jaideep; Walmsley, Russell; Milne, David; Jafer, Ali; Gordon-Glassford, Noel
2015-01-01
A 41-year-old man with no previous asbestos exposure presented with 6 months of dull right lower chest pain and weight loss. The initial computed tomography (CT) scan was reported as showing a soft tissue thickening in the posterior mediastinum with non-specific nodules in the horizontal and oblique fissures. An endoscopic ultrasound-guided fine needle aspiration from the 12?×?25?mm heterogeneous posterior mediastinal mass was suspicious for a ganglioneuroma. The procedure was complicated by a large hemothorax requiring drainage. A subsequent positron emission tomographic CT revealed a moderately fluorodeoxyglucose avid area of pleural thickening extending from the sixth to ninth thoracic vertebral body in the paraspinal region along with nodules along the right horizontal and oblique fissures. A thoracoscopic biopsy of the pleural lesion confirmed a pleural epithelioid hemangioendothelioma. There was a 5-mm reduction in tumor thickness and improvement in his pain following 54?Gy of radiotherapy.
Posterior Reversible Encephalopathy Syndrome in late postpartum eclampsia.
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
Double-Bundle “All-Inside” Posterior Cruciate Ligament Reconstruction
Slullitel, Daniel; Galan, Hernan; Ojeda, Vanina; Seri, Matias
2012-01-01
The procedure for repairing the posterior cruciate ligament (PCL) has a steep learning curve and entails numerous difficult steps during surgery, because of the proximity of the neurovascular bundle, difficult passage of the graft through the posterior capsule, and risk of poor tibial fixation because of the long intramedullary trajectory of the graft. The use of instruments for retrograde reaming and a new device for adjustable cortical suspensory fixation allows for a safe, reproducible all-inside double-bundle PCL reconstruction by simplifying these difficult steps. We used anterior tibial allograft or hamstring autograft together with adjustable suspensory fixation devices that allow tensioning (after fixation) of the posterolateral bundle in extension and the anteromedial bundle in flexion. PMID:23766986
A case of hypospadias, anterior and posterior urethral valves.
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
Paediatric intra-axial posterior fossa tumours: pictorial review.
Rasalkar, Darshana D; Chu, Winnie Chiu-Wing; Paunipagar, Bhawan K; Cheng, Frankie W T; Li, C K
2013-01-01
Paediatric brain tumours commonly arise in the posterior cranial fossa. Early diagnosis is often challenging due to initial non-specific clinical symptoms, especially in very young children. The typical MR features of tumours in this region including medulloblastoma, ependymoma, juvenile pilocytic subtype of cerebellar astrocytoma, brain stem glioma and atypical teratoid-rhabdoid tumour are illustrated. Diffusion-weighted imaging and apparent diffusion coefficient values combined with signal characteristics on conventional MR sequences can usually differentiate low-grade from high-grade tumours. Prompt diagnosis is crucial as total surgical resection, which is only possible in localised disease, improves prognosis. A practical MR flow chart is introduced for differentiating different types of posterior cranial fossa tumours, which might be useful in clinical practice. PMID:22977284
SHOULDER POSTERIOR INTERNAL IMPINGEMENT IN THE OVERHEAD ATHLETE
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
Hippocampal sclerosis and chronic epilepsy following posterior reversible encephalopathy syndrome.
Kapina, Viktoria; Vargas, Maria-Isabel; Wohlrab, Gabriele; Vulliemoz, Serge; Fluss, Joel; Seeck, Margitta
2013-12-01
Chronic epilepsy has rarely been reported after posterior reversible encephalopathy syndrome (PRES) and the association with hippocampal sclerosis has been suggested only once before. We report the case of a girl admitted at the age of 8 years with idiopathic nephrotic syndrome. On the second day of admission, she presented with focal complex seizures and cerebral MRI showed posterior encephalopathy and no hippocampal sclerosis. MRI after one month confirmed the diagnosis of PRES. The seizures recurred and the girl developed pharmacoresistant epilepsy and was admitted to our hospital for further investigation. Cerebral MRI three years after the diagnosis of PRES showed hippocampal sclerosis which was not present on the initial MRI. We conclude that there is a triggering role of PRES in the development of hippocampal sclerosis. Hippocampal sclerosis may have resulted from seizure-associated damage, alternatively, hypertensive encephalopathy may have led to hippocampal damage via a vascular mechanism. PMID:24515311
Superior labrum anterior to posterior lesions and the superior labrum.
Rowbotham, Emma L; Grainger, Andrew J
2015-07-01
The fibrocartilaginous glenoid labrum contributes to shoulder stability and provides attachment for the long head of biceps tendon and the glenohumeral ligaments. The superior site of attachment of the long head of biceps (biceps anchor) represents a site of injury to the superior labrum where tearing may extend into the biceps tendon as well as anterior and/or posterior to the biceps anchor. Such tears are known as superior labrum anterior and posterior (SLAP) tears and are a cause of both shoulder instability and pain. SLAP tears are frequently seen in those undertaking repetitive frequent overarm activity such as throwing athletes and swimmers. This article reviews the mechanisms and types of SLAP tears and their imaging appearances. It also discusses associated injuries and pitfalls in diagnosing these injuries. PMID:26021587
Early treatment of posterior crossbite - a randomised clinical trial
2013-01-01
Background The aim of this randomised clinical trial was to assess the effect of early orthodontic treatment in contrast to normal growth effects for functional unilateral posterior crossbite in the late deciduous and early mixed dentition by means of three-dimensional digital model analysis. Methods This randomised clinical trial was assessed to analyse the orthodontic treatment effects for patients with functional unilateral posterior crossbite in the late deciduous and early mixed dentition using a two-step procedure: initial maxillary expansion followed by a U-bow activator therapy. In the treatment group 31 patients and in the control group 35 patients with a mean age of 7.3 years (SD 2.1) were monitored. The time between the initial assessment (T1) and the follow-up (T2) was one year. The orthodontic analysis was done by a three-dimensional digital model analysis. Using the ‘Digimodel’ software, the orthodontic measurements in the maxilla and mandible and for the midline deviation, the overjet and overbite were recorded. Results Significant differences between the control and the therapy group at T2 were detected for the anterior, median and posterior transversal dimensions of the maxilla, the palatal depth, the palatal base arch length, the maxillary arch length and inclination, the midline deviation, the overjet and the overbite. Conclusions Orthodontic treatment of a functional unilateral posterior crossbite with a bonded maxillary expansion device followed by U-bow activator therapy in the late deciduous and early mixed dentition is an effective therapeutic method, as evidenced by the results of this RCT. It leads to three-dimensional therapeutically induced maxillary growth effects. Dental occlusion is significantly improved, and the prognosis for normal craniofacial growth is enhanced. Trial registration Registration trial DRKS00003497 on DRKS PMID:23339736
Non-traumatic posterior atlanto-occipital joint dislocation
Yasuhiko Takechi; Haku Iizuka; Yasunori Sorimachi; Tsuyoshi Ara; Masahiro Nishinome; Kenji Takagishi
2011-01-01
This report presents a case of non-traumatic posterior atlanto-occipital dislocation. A 36-year-old female was referred with\\u000a a history of numbness of the extremities, vertigo and neck pain for 1 year. The patient had no history of trauma. The axial\\u000a rotation of range of motion of the cervical spine was severely restricted. A lateral cervical radiograph in the neutral position\\u000a demonstrated a
Reversible posterior leukoencephalopathy syndrome in a patient with Takayasu arteritis
Masaaki Fujita; Kenichi Komatsu; Saori Hatachi; Masato Yagita
2008-01-01
Reversible posterior leukoencephalopathy syndrome (RPLS) has been identified in several connective tissue diseases. However,\\u000a there are no reports of RPLS associated with Takayasu arteritis (TA). We report the first case of TA associated with RPLS.\\u000a A 23-year-old woman presented with sudden headache and vomiting, followed by generalized tonic–clonic seizures and mental\\u000a changes two weeks after administration of oral prednisolone. MRI
Surgical treatment of thoracic disc herniations via tailored posterior approaches
Wolfgang Börm; U. Bäzner; R. W. König; T. Kretschmer; G. Antoniadis; J. Kandenwein
We present clinical findings, radiological characteristics and surgical modalities of various posterior approaches to thoracic\\u000a disc herniations and report the clinical results in 27 consecutive patients. Within an 8-year period 27 consecutive patients\\u000a (17 female, 10 male) aged 30–83 years (mean 53 years.) were surgically treated for 28 symptomatic herniated thoracic discs\\u000a in our department. Six of these lesions (21%) were calcified.
Urodynamic evaluation in boys treated for posterior urethral valves
R. Lal; V. Bhatnagar; S. Agarwala; V. P. Grover; D. K. Mitra
1999-01-01
This study describes the urodynamic findings in 22 patients with posterior urethral valves and discusses their association\\u000a with urinary incontinence, age, mode of primary treatment, renal function, and changes in the upper tracts. The patients'\\u000a ages ranged from 3 to 26 years and 27% were either adolescents or older. The urodynamic findings were categorized into 5 main\\u000a patterns, although mixed
Posterior urethral valves after infancy–urodynamic consequences
A. Krishna; P. Lal; A. Gupta; U. Madan
1998-01-01
This study describes a subset of patients with posterior urethral valves (PUV) who presented late in childhood. The objective\\u000a was to identify factors that lead to back-pressure effects on the upper tracts, which persist in spite of adequate valve ablation\\u000a in some patients, and seek factors that may preserve the upper tracts despite untreated obstruction in other patients. Six\\u000a children
Factors affecting outcome in the management of posterior urethral valves
M. Bajpai; S. Dave; D. K. Gupta
2001-01-01
Children with posterior urethral valves (PUV) are at high risk for renal failure (RF). The outcome of renal function is significantly\\u000a influenced by early diagnosis and the choice of primary therapy. We reviewed the outcome of renal function in 58 children\\u000a with PUV. The choice of therapy in each case – primary valve fulguration, vesicostomy, or high ureterostomy – was
Prognostic factors in Saudi children with posterior urethral valves
Vincent C. Onuora; Khalid Mirza; Abdelmoniem H. Koko; M. Al Turki; Ahmed H. Meabed; N. Al Jawini
2000-01-01
Posterior urethral valves (PUV) account for a sizeable proportion of children with chronic renal failure. Several criteria\\u000a have been identified as predictive of future renal function in children with PUV. We compared the presenting features and\\u000a initial treatment in two groups of Saudi children treated for PUV, with the aim of identifying any factors that might account\\u000a for the differences
Renal transplantation in children with posterior urethral valves
Santiago Mendizabal; Isabel Zamora; Agustin Serrano; Maria Jose Sanahuja; Ezena Roman; Carlos Dominguez; Pedro Ortega; Fernando García Ibarra
2006-01-01
The objective of this study was to analyze whether renal transplantation (RT) in children with posterior urethral valves (PUV)\\u000a constitutes a special group with respect to groups with different etiologies of end-stage renal disease (ESRD). Between 1979\\u000a and 2004, 22 RT were performed in 19 children with PUV. The median age at RT was 10 years (range: 1.3–17). Immunosuppression\\u000a was provided
Posterior urethral valves: the scenario in a developing center
S. K. Chatterjee; S. Banerjee; D. Basak; A. K. Basu; A. K. Chakravarti; J. Haque
2001-01-01
We have reviewed 233 patients with posterior urethral valves treated in a single center in Calcutta, India, over the last\\u000a 20 years: 37 were neonates, 75 were between 1 and 12 months, 88 were between 1 and 5 years, and 33 were more than 5 years\\u000a old when first seen. The clinical presentation and methods employed in diagnosis and assessment
Anterior-posterior patterning within the Caenorhabditis elegans endoderm.
Schroeder, D F; McGhee, J D
1998-12-01
The endoderm of higher organisms is extensively patterned along the anterior/posterior axis. Although the endoderm (gut or E lineage) of the nematode Caenorhabditis elegans appears to be a simple uniform tube, cells in the anterior gut show several molecular and anatomical differences from cells in the posterior gut. In particular, the gut esterase ges-1 gene, which is normally expressed in all cells of the endoderm, is expressed only in the anterior-most gut cells when certain sequences in the ges-1 promoter are deleted. Using such a deleted ges-1 transgene as a biochemical marker of differentiation, we have investigated the basis of anterior-posterior gut patterning in C. elegans. Although homeotic genes are involved in endoderm patterning in other organisms, we show that anterior gut markers are expressed normally in C. elegans embryos lacking genes of the homeotic cluster. Although signalling from the mesoderm is involved in endoderm patterning in other organisms, we show that ablation of all non-gut blastomeres from the C. elegans embryo does not affect anterior gut marker expression; furthermore, ectopic guts produced by genetic transformation express anterior gut markers generally in the expected location and in the expected number of cells. We conclude that anterior gut fate requires no specific cell-cell contact but rather is produced autonomously within the E lineage. Cytochalasin D blocking experiments fully support this conclusion. Finally, the HMG protein POP-1, a downstream component of the Wnt signalling pathway, has recently been shown to be important in many anterior/posterior fate decisions during C. elegans embryogenesis (Lin, R., Hill, R. J. and Priess, J. R. (1998) Cell 92, 229-239). When RNA-mediated interference is used to eliminate pop-1 function from the embryo, gut is still produced but anterior gut marker expression is abolished. We suggest that the C. elegans endoderm is patterned by elements of the Wnt/pop-1 signalling pathway acting autonomously within the E lineage. PMID:9811572
Comprehensive gait analysis in posterior-stabilized knee arthroplasty
Stephen A. Wilson; Peter D. McCann; Robert S. Gotlin; H. K. Ramakrishnan; Mary E. Wootten; John N. Insall
1996-01-01
Sixteen patients implanted with a posterior-stabilized prosthesis (Insall-Burstein PS II, Zimmer, Warsaw, IN) and 32 age-matched control subjects were evaluated by isokinetic muscle testing and comprehensive gait analysis at a mean 46 months following the index arthroplasty. The contralateral knee was normal in 13 patients and an asymptomatic total knee arthroplasty in 3 patients. No significant differences (P > .05)
Unicentric Castleman's disease: an uncommon cause of posterior mediastinal mass
Alavi, Aliasghar; Asadi Gharabaghi, Mehrnaz
2013-01-01
Castleman's disease is a rare lymphoproliferative disease that may be unicentric or multicentric in presentation. It may develop anywhere along with the lymphatic system such as the abdomen, neck and thoracic cavity. However, mediastinum is the most common location for unicentric disease. Here, we discuss a unicentric Castleman's disease in a 28-year-old woman who presented with cough, mild dysphagia and a large posterior mediastinal mass. PMID:23761562
Ependymomas of the posterior cranial fossa: CT and MRI findings
P. Tortori-Donati; M. P. Fondelli; A. Cama; M. L. Garrè; A. Rossi; L. Andreussi
1995-01-01
We studied nine children with posterior cranial fossa ependymomas to identify specific neuroradiological features. Patients were studied preoperatively with CT and MRI; T1-, T2-and proton-density (PD)-weighted images were obtained. All children underwent surgery and a definite histopathological diagnosis was made. All the tumours grew into the fourth ventricle and caused dilatation of its upper part, which resembled a cap. All
Ependymomas of the posterior cranial fossa: CT and MRI findings
P. Tortori-Donati; M. P. Fondelli; A. Cama; M. L. Garrè; A. Rossi; L. Andreussi
1995-01-01
We studied nine children with posterior cranial fossa ependymomas to identify specific neuroradiological features. Patients were studied preoperatively with CT and MRI; T1-, T2- and proton-density (PD)-weighted images were obtained. All children underwent surgery and a definite histopathological diagnosis was made. All the tumours grew into the fourth ventricle and caused dilatation of its upper part, which resembled a cap.
Frontal and Posterior Subtypes of Neuropsychological Deficit in Parkinson's Disease
Miller, Ivy N.; Neargarder, Sandy; Risi, Megan M.; Cronin–Golomb, Alice
2013-01-01
Mild cognitive impairment in Parkinson's disease (PD) is heterogeneous in regard to affected domains. Although patterns of cognitive performance that may predict later dementia are as yet undetermined, posterior-versus frontal-type assessments show promise for differential predictive value. The present study included 70 individuals: 42 with idiopathic PD without dementia and 28 age- and education-matched healthy control adults (HC). Participants completed assessments of cognition with emphasis on tests that are sensitive to frontal and posterior deficits. PD patients were classified into cognitive subgroups and the subgroups were compared on demographic and disease variables. Individual performance across neuropsychological tests was evaluated for the PD group. Patients with PD performed more poorly than HC on several measures of cognition, and they were classified into frontal (12), posterior (3), both (10) and neither subgroups (17), the latter two in reference to frontal- and posterior-type deficits. The neither subgroup was distinguished by less motor impairment than the both subgroup, but the four subgroups did not otherwise differ on demographic or disease variables. Across patients, the tests most sensitive to cognitive impairment included measures of attention and executive functioning (frontal-type tests). Examination of individual test performance for PD revealed substantial heterogeneity across tests with respect to number and severity of deficits. The current study provides insight into which commonly used neuropsychological tests are most sensitive to cognitive deficits (strictly defined) in a nondemented, well characterized PD sample, and into the relation of cognitive subgroups to demographic and disease-specific variables. PMID:23398433
Novel Drug Delivery Systems for Posterior Segment Ocular Disease
Heather Sheardown; W. Mark Saltzman
Delivery of drugs to the eye, particularly for the treatment of posterior segment diseases, is a challenging task that requires\\u000a drug transport across barriers in the eye, which are present for the purpose of limiting the entry of drugs and xenobiotics.\\u000a The common methods of drug delivery to the eye—eyedrops, direct injection, and systemic administration—all have problems that\\u000a limit their
Bayesian updating of a probability distribution encoded on a quantum register
Andrei N. Soklakov; Ruediger Schack
2005-11-22
We investigate the problem of Bayesian updating of a probability distribution encoded in the quantum state of n qubits. The updating procedure takes the form of a quantum algorithm that prepares the quantum register in the state representing the posterior distribution. Depending on how the prior distribution is given, we describe two implementations, one probabilistic and one deterministic, of such an algorithm in the standard model of a quantum computer.
[The posterior menisco-femoral ligaments and their significance in organogenesis].
Lahlaidi, A; Vaclavek, J
1975-03-01
In the knee joint, there are two sorts of posterior menisco-femoral ligaments, one of them, on the lateral side binds the posterior edge of the meniscus with the femur, the other on the medial side attaches a part of the meniscal horn to the posterior cruciate ligament or to the femur. The differentiation of these ligamentous bundles seems to be bound with the organogenetic varieties of the posterior cruciate ligament. PMID:1222290
Yoshinori Ishii; Kazuhiro Terajima; Yoshio Koga; Hideaki E. Takahashi; Joan E. Bechtold; Ramon B. Gustilo
1998-01-01
: The objective of this study was to measure three-dimensional knee motion during gait in patients with total knee replacements\\u000a which either retained the posterior cruciate ligament (n = 11), or required sacrifice of the posterior cruciate ligament and replacement of its function with a posterior stabilizing\\u000a articular surface (n = 9). Clinically meaningful translations (anterior and posterior, medial and
The Great Imitator: Ocular Syphilis Presenting as Posterior Uveitis.
Kuo, Alan; Ziaee, Saba M; Hosseini, Hamid; Voleti, Vinod; Schwartz, Steven D; Kim, Nam U; Ge, Phillip S
2015-01-01
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
Macular Development in Aggressive Posterior Retinopathy of Prematurity
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 5–10 days to examine areas previously hidden by neovascularization to ensure prudent therapy. Macular development involves both transverse and anterior-posterior growth.
Intensity-Modulated Arc Therapy for Pediatric Posterior Fossa Tumors
Beltran, Chris, E-mail: chris.beltran@stjude.org [Department of Radiological Sciences, St. Jude Children's Research Hospital, Memphis, TN (United States); Gray, Jonathan; Merchant, Thomas E. [Department of Radiological Sciences, St. Jude Children's Research Hospital, Memphis, TN (United States)
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.
The Great Imitator: Ocular Syphilis Presenting as Posterior Uveitis
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
Posterior predictive model checks for disease mapping models.
Stern, H S; Cressie, N
Disease incidence or disease mortality rates for small areas are often displayed on maps. Maps of raw rates, disease counts divided by the total population at risk, have been criticized as unreliable due to non-constant variance associated with heterogeneity in base population size. This has led to the use of model-based Bayes or empirical Bayes point estimates for map creation. Because the maps have important epidemiological and political consequences, for example, they are often used to identify small areas with unusually high or low unexplained risk, it is important that the assumptions of the underlying models be scrutinized. We review the use of posterior predictive model checks, which compare features of the observed data to the same features of replicate data generated under the model, for assessing model fitness. One crucial issue is whether extrema are potentially important epidemiological findings or merely evidence of poor model fit. We propose the use of the cross-validation posterior predictive distribution, obtained by reanalyzing the data without a suspect small area, as a method for assessing whether the observed count in the area is consistent with the model. Because it may not be feasible to actually reanalyze the data for each suspect small area in large data sets, two methods for approximating the cross-validation posterior predictive distribution are described. PMID:10960860
J. G. Titus; V. K. Narayanan
1995-01-01
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.
Solar elevation angle probability distribution
D. C. Larson; C. R. Acquista
1980-01-01
The probability distribution of solar elevation angles is determined, and the importance of this distribution on concentrator design is discussed. It is concluded that the time probability function for the solar elevation angle is important when considering alternative low-concentration systems for year-round or seasonal applications.
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.
DAU StatRefresher: Probability
NSDL National Science Digital Library
These tutorials, hosted by George Mason University, on probability cover basic probability, random variables, expectations, and distributions. Each lesson provides a definition, the concepts behind each theory and then exercises for students to practice these concepts. This is just one set of concepts in a much larger repository of lessons.
Verification of Categorical Probability Forecasts
H. Zhang; T. Casey
2000-01-01
This paper compares a number of probabilistic weather forecasting verification approaches. Forecasting skill scores from linear error in probability space and relative operating characteristics are compared with results from an alternative approach that first transforms probabilistic forecasts to yes\\/no form and then assesses the model forecasting skill. This approach requires a certain departure between the categorical probability from forecast models
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.
Time, Quantum Mechanics, and Probability
Simon Saunders
2001-11-07
A "geometric" intepretation of probability is proposed, modelled on the treatment of tense in 4-dimensional spacetime. It is applied to Everett's approach to quantum mechanics, as formulated in terms of consistent histories. Standard objections to Everett's approach, based on the difficulties of interpreting probability in its terms, are considered in detail, but found to be wanting.
Anil Arat; Civan Islak; Isil Saatci; Naci Kocer; Saruhan Cekirge
2002-01-01
. Posterior cerebral artery aneurysms are amenable to deconstructive surgical treatment because of the rich collateral supply of the distal posterior cerebral artery. This report retrospectively analyses the outcome of endovascular parent artery occlusion for large or fusiform distal posterior cerebral artery aneurysms. Medical records and cerebral angiograms from two endovascular centres were analysed retrospectively. Eight patients with large or
Walid Farhat; Gordon McLorie; Gianpaolo Capolicchio; Antoine Khoury; Darius Bägli; Paul A Merguerian
2000-01-01
Objectives. Although valve ablation is the treatment of choice for patients with posterior urethral valves, debate continues as to the role of urinary diversion. We sought to retrospectively compare the clinical and radiologic outcomes between valve ablation and urinary diversion for patients with posterior urethral valves.Methods. We retrospectively reviewed the records of 50 consecutive patients with posterior urethral valves since
Long-term Results of Primary Avulsion of Posterior Urethral Valves Using A Fogarty Balloon Catheter
Boris Chertin; Denis Cozzi; Prem Puri
2002-01-01
PurposePosterior urethral valves are the most common cause of bladder outlet obstruction in infancy and cause renal failure in 25% to 30% of these children before adolescence. Transurethral ablation under direct vision is the most commonly used method of treatment for posterior urethral valves. Since 1987 we have used a Fogarty balloon catheter for primary avulsion of the posterior urethral
Bipolar Posterior Deltoid Transfer for Massive Rotator Cuff Tears: A Report on 2 Patients
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
Ossenkoppele, Rik; Mattsson, Niklas; Teunissen, Charlotte E; Barkhof, Frederik; Pijnenburg, Yolande; Scheltens, Philip; van der Flier, Wiesje M; Rabinovici, Gil D
2015-08-01
Different clinical variants of probable Alzheimer's disease (AD) share underlying plaques and tangles but show distinct atrophy patterns. We included 52 posterior cortical atrophy, 29 logopenic variant primary progressive aphasia, 53 early-onset and 42 late-onset AD patients, selected for abnormal cerebrospinal fluid (CSF)-amyloid-beta42, with CSF and magnetic resonance imaging data available. Bootstrapping revealed no differences in the prevalence of abnormal CSF total-tau and phosphorylated-tau between probable AD variants (range total-tau: 84.9%-92.3%, phosphorylated-tau: 79.2%-93.1%, p > 0.05). Voxelwise linear regressions showed various relationships between lower CSF-A?42 and syndrome-specific atrophy, involving precuneus, posterior cingulate, and medial temporal lobe in early-onset AD, occipital cortex and middle temporal gyrus in posterior cortical atrophy; anterior cingulate, insular cortex and precentral gyrus (left > right) in logopenic variant primary progressive aphasia; and medial temporal lobe, thalamus, and temporal pole in late-onset AD (all at p < 0.001 uncorrected). In contrast, CSF-tau was not related to gray matter atrophy in any group. Our findings suggest that lower CSF-amyloid-beta42 - and not increased total-tau and phosphorylated-tau - relates to reduced gray matter volumes, mostly in regions that are typically atrophied in distinct clinical variants of probable AD. PMID:25990306
Arthroscopic posterior cruciate ligament reconstruction with allograft versus autograft
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
Gamma Knife radiosurgery for posterior fossa meningiomas: a multicenter study.
Sheehan, Jason P; Starke, Robert M; Kano, Hideyuki; Barnett, Gene H; Mathieu, David; Chiang, Veronica; Yu, James B; Hess, Judith; McBride, Heyoung L; Honea, Norissa; Nakaji, Peter; Lee, John Y K; Rahmathulla, Gazanfar; Evanoff, Wendi A; Alonso-Basanta, Michelle; Lunsford, L Dade
2015-06-01
OBJECT Posterior fossa meningiomas represent a common yet challenging clinical entity. They are often associated with neurovascular structures and adjacent to the brainstem. Resection can be undertaken for posterior fossa meningiomas, but residual or recurrent tumor is frequent. Stereotactic radiosurgery (SRS) has been used to treat meningiomas, and this study evaluates the outcome of this approach for those located in the posterior fossa. METHODS At 7 medical centers participating in the North American Gamma Knife Consortium, 675 patients undergoing SRS for a posterior fossa meningioma were identified, and clinical and radiological data were obtained for these cases. Females outnumbered males at a ratio of 3.8 to 1, and the median patient age was 57.6 years (range 12-89 years). Prior resection was performed in 43.3% of the patient sample. The mean tumor volume was 6.5 cm(3), and a median margin dose of 13.6 Gy (range 8-40 Gy) was delivered to the tumor. RESULTS At a mean follow-up of 60.1 months, tumor control was achieved in 91.2% of cases. Actuarial tumor control was 95%, 92%, and 81% at 3, 5, and 10 years after radiosurgery. Factors predictive of tumor progression included age greater than 65 years (hazard ratio [HR] 2.36, 95% CI 1.30-4.29, p = 0.005), prior history of radiotherapy (HR 5.19, 95% CI 1.69-15.94, p = 0.004), and increasing tumor volume (HR 1.05, 95% CI 1.01-1.08, p = 0.005). Clinical stability or improvement was achieved in 92.3% of patients. Increasing tumor volume (odds ratio [OR] 1.06, 95% CI 1.01-1.10, p = 0.009) and clival, petrous, or cerebellopontine angle location as compared with petroclival, tentorial, and foramen magnum location (OR 1.95, 95% CI 1.05-3.65, p = 0.036) were predictive of neurological decline after radiosurgery. After radiosurgery, ventriculoperitoneal shunt placement, resection, and radiation therapy were performed in 1.6%, 3.6%, and 1.5%, respectively. CONCLUSIONS Stereotactic radiosurgery affords a high rate of tumor control and neurological preservation for patients with posterior fossa meningiomas. Those with a smaller tumor volume and no prior radiation therapy were more likely to have a favorable response after radiosurgery. Rarely, additional procedures may be required for hydrocephalus or tumor progression. PMID:25859812
Failure probability under parameter uncertainty.
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
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.
Probability Machines: Consistent Probability Estimation Using Nonparametric Learning Machines
Malley, J. D.; Kruppa, J.; Dasgupta, A.; Malley, K. G.; Ziegler, A.
2011-01-01
Summary Background Most machine learning approaches only provide a classification for binary responses. However, probabilities are required for risk estimation using individual patient characteristics. It has been shown recently that every statistical learning machine known to be consistent for a nonparametric regression problem is a probability machine that is provably consistent for this estimation problem. Objectives The aim of this paper is to show how random forests and nearest neighbors can be used for consistent estimation of individual probabilities. Methods Two random forest algorithms and two nearest neighbor algorithms are described in detail for estimation of individual probabilities. We discuss the consistency of random forests, nearest neighbors and other learning machines in detail. We conduct a simulation study to illustrate the validity of the methods. We exemplify the algorithms by analyzing two well-known data sets on the diagnosis of appendicitis and the diagnosis of diabetes in Pima Indians. Results Simulations demonstrate the validity of the method. With the real data application, we show the accuracy and practicality of this approach. We provide sample code from R packages in which the probability estimation is already available. This means that all calculations can be performed using existing software. Conclusions Random forest algorithms as well as nearest neighbor approaches are valid machine learning methods for estimating individual probabilities for binary responses. Freely available implementations are available in R and may be used for applications. PMID:21915433
On quantum vs. classical probability
Rau, Jochen [Institut fuer Theoretische Physik, Johann Wolfgang Goethe-Universitaet, Max-von-Laue-Str. 1, 60438 Frankfurt am Main (Germany)], E-mail: jochen.rau@q-info.org
2009-12-15
Quantum theory shares with classical probability theory many important properties. I show that this common core regards at least the following six areas, and I provide details on each of these: the logic of propositions, symmetry, probabilities, composition of systems, state preparation and reductionism. The essential distinction between classical and quantum theory, on the other hand, is shown to be joint decidability versus smoothness; for the latter in particular I supply ample explanation and motivation. Finally, I argue that beyond quantum theory there are no other generalisations of classical probability theory that are relevant to physics.
Introduction to Probability and Statistics
NSDL National Science Digital Library
Panchenko, Dmitry
Published by MIT and created by Professor Dmitry Panchenko for the Spring semester of 2005, this online course provides an introduction to probability and statistics for undergraduate students. The topics included are "basic probability models; combinatorics; random variables; discrete and continuous probability distributions; statistical estimation and testing; confidence intervals; and an introduction to linear regression." All lecture notes, assignments, and exams are available as PDF files. This is a fantastic and free way for educators and students to harness the quality education of MIT and bring it into their own classrooms.
Accurate Structural Correlations from Maximum Likelihood Superpositions
Douglas L. Theobald; Deborah S. Wuttke
2008-01-01
The cores of globular proteins are densely packed, resulting in complicated networks of structural interactions. These interactions in turn give rise to dynamic structural correlations over a wide range of time scales. Accurate analysis of these complex correlations is crucial for understanding biomolecular mechanisms and for relating structure to function. Here we report a highly accurate technique for inferring the
Coding of Reward Probability and Risk by Single Neurons in Animals
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
Recent progress in the diagnosis and treatment of posterior tibial plateau fractures
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
VESPA: False positive probabilities calculator
NASA Astrophysics Data System (ADS)
Morton, Timothy D.
2015-03-01
Validation of Exoplanet Signals using a Probabilistic Algorithm (VESPA) calculates false positive probabilities and statistically validates transiting exoplanets. Written in Python, it uses isochrones [ascl:1503.010] and the package simpledist.
Probability in a Primary School
NSDL National Science Digital Library
Sherwood, Philip
This reference material, created by Philip Sherwood, provides various activities and tasks, which help elementary aged children understand the concepts of probability. The author has a nice series of diagrams intertwined within the text to help illustrate these concepts.
Probability and Statistics Object Library
NSDL National Science Digital Library
Siegrist, Kyle
This library contains a plethora of downloadable applets and the components of the applets for use by teachers and students of probability and statistics. These objects (both executable files and source code) can be downloaded, modified if desired, and reused.
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.
Joint probabilities and quantum cognition
Acacio de Barros, J. [Liberal Studies, 1600 Holloway Ave., San Francisco State University, San Francisco, CA 94132 (United States)
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.
Joint probabilities and quantum cognition
de Barros, J Acacio
2012-01-01
In this paper we discuss the existence of joint probability distributions for quantum-like 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.
Posterior interosseous nerve incarceration with endobutton repair of distal biceps.
Van den Bogaerde, James; Shin, Edward
2015-01-01
Distal biceps ruptures are uncommon injuries that comprise approximately 3% of all biceps pathology. This injury is most commonly seen in 40- to 60-year-old men, and the mechanism of injury involves a forceful extension movement to a flexed elbow. Without surgical intervention, patients are left with measurable weakness in elbow flexion and supination as well as a cosmetic deformity that often leaves them dissatisfied. Consequently, early surgical repair is advocated for physically active individuals. A variety of surgical approaches and fixation devices are currently used for distal biceps repair. The single-incision cortical button repair for distal biceps avulsions has become popular since Bain introduced the technique in 2000. The advantage of the cortical button biceps repair technique is the significantly higher failure strength than either the 2-incision technique or the suture anchor repair. The initial repair strength of the cortical button technique allows immediate active elbow range of motion and accelerated rehabilitation. Additionally, the single-incision anterior approach is less invasive than the 2-incision biceps repair and results in a lower incidence of heterotopic ossification. One disadvantage of this approach, however, is the risk of injury to the posterior interosseous nerve. The authors report a case in which the posterior interosseous nerve was incarcerated between the cortical button and the radius during acute distal biceps repair, resulting in complete posterior interosseus nerve palsy. This case report details the surgery leading to the nerve palsy and the subsequent nerve exploration that identified the cause of the nerve palsy. Recommendations are made on how to avoid this complication during distal biceps tendon repairs. PMID:25611423
Experimental lens capsular bag model for posterior capsule opacification.
Jun, Jong Hwa; Sohn, Wern-Joo; Lee, Youngkyun; Chang, Sung Dong; Kim, Jae-Young
2014-07-01
An in vitro culture model enabling posterior capsule opacification (PCO) to be investigated was developed and established by using low-melting-point (LMP)-agarose gel to support the capsular bag. After removal of the cornea from rodent and porcine eyeballs, the lens zonules were dissected. Whole lens explants were embedded into 2 % (37 °C) LMP-agarose gel solution. As performed routinely in cataract surgery, capsulotomy and lens fiber removal were carried out in the solidified LMP-agarose gel as sham cataract surgery. The LMP-agarose-gel-supported capsular bag/lens epithelial cell (CB-LEC) complexes were maintained in Dulbecco's modified Eagle medium supplemented with 10 % fetal bovine serum in an anterior face-down position. The proliferation and migration of LECs into the posterior capsule were observed every 12 h by phase-contrast microscopy. Epithelial cells were observed at the central portion of the CB-LEC complexes after 56.57?±?16.56 h (n?=?7) and 106?±?14.03 h (n?=?6) of culture, for rodent and porcine lenses, respectively. The solidified gel allowed clear microscopic observations and whole-mount immunostaining evaluations of the whole area of the capsular bag. Histological examinations revealed the proliferation, migration, and transdifferentiation of LECs related to posterior capsule opacification. This new in vitro culture model provides experimental benefits by maintaining the natural contour of the capsule without implants inside or outside of the capsule. In addition, this model system allows pharmacological and histological evaluations of the cultured CB-LEC complexes without additional manipulations. PMID:24793776
Minimally invasive tubular access for posterior cervical foraminotomy
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
Management of presacral tumors: Our experience with posterior approach
Saxena, Dhananjay; Pandey, Abhinav; Bugalia, Rajendra Prasad; Kumar, Mahendra; Kadam, Raju; Agarwal, Vipul; Goyal, Amit; Kankaria, Jeevan; Jenaw, Raj Kamal
2015-01-01
Introduction Presacral tumors are a rare variety of space occupying lesions arising in the presacral space. Most of the tumors are congenital in origin. Due to obscure anatomic location, difficult surgical approach and etiological heterogeneity, tumors arising here pose a diagnostic and therapeutic challenge. We report our experience of 10 cases of presacral tumors with posterior approach being used in 6. Materials and methods A retrospective analysis was conducted on 10 cases of presacral tumors managed at our hospital during a period of 14 months (May 2013–July 2014). 9 cases were operated while one had advanced disease and was referred for palliative care. Complete en bloc excision of the mass was possible in 8 cases. Finally, presenting complaints, clinical diagnosis, surgical procedure and histopahological findings of the cases were studied. Results All of our patients were females in the age group of 18–50 (mean 28.4) years. The pathological findings included schwannoma, leiomyosarcoma, hemangiopericytoma, neurofibroma, paraganglioma and rest were developmental cysts. 6 cases were managed using the posterior approach and rest by anterior approach. There was no major complication or mortality in the follow up. Conclusion Complete surgical excision remains the mainstay of therapy. Surgical approach depends upon the location, size, local invasion and surgical expertise of the surgeon. Benign tumors have a good prognosis while the prognosis in malignant tumors remains guarded due to difficulty in obtaining safe resection margins. Posterior approach is an attractive option for low lying, benign tumors that is more direct, with better exposure and quicker recovery. PMID:25996775
Carsten Schmidt; Axel Werwatz
2002-01-01
For the Euro 2000 Soccer Championships an experimental asset market was conducted, with traders buying and selling contracts on the winners of individual matches. Market-generated probabilities are compared to professional bet quotas, and factors that are responsible for the quality of the market prognosis are identified. The comparison shows, that the market is more accurate than the random predictor and
Thermochemistry and accurate quantum reaction rate calculations for H2\\/HD\\/D2 + CH3
Gunnar Nyman; Rob van Harrevelt; Uwe Manthe
2007-01-01
Accurate quantum-mechanical results for thermodynamic data, cumulative reaction probabilities (for J = 0), thermal rate constants, and kinetic isotope effects for the three isotopic reactions H-2 + CH3 -> CH4 + H, HD + CH3 -> CH4 + D, and D-2 + CH3 -> CH3D + D are presented. The calculations are performed using flux correlation functions and the multiconfigurational
The probability of causal conditionals.
Over, David E; Hadjichristidis, Constantinos; Evans, Jonathan St B T; Handley, Simon J; Sloman, Steven A
2007-02-01
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/p). We report three experiments on causal indicative conditionals and related counterfactuals that support this hypothesis. We measured the probabilities people assigned to truth table cases, P(pq), P(p notq), P( notpq) and P( notp notq). From these ratings, we computed three independent predictors, P(p), P(q/p) and P(q/ notp), that we then entered into a regression equation with judged P(if p then q) as the dependent variable. In line with the conditional probability hypothesis, P(q/p) was by far the strongest predictor in our experiments. This result is inconsistent with the claim that causal conditionals are the material conditionals of elementary logic. Instead, it supports the Ramsey test hypothesis, implying that common processes underlie the use of conditionals in reasoning and judgments of conditional probability in decision making. PMID:16839539
Osteochondroma of Maxilla Posterior Region: A Unique Case
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
Considerations for ceramic inlays in posterior teeth: a review
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
Miyake-Apple posterior video analysis/photographic technique.
Pereira, Frederico A S; Werner, Liliana; Milverton, E John; Coroneo, Minas T
2009-03-01
The Miyake-Apple technique for posterior photography and video analysis of postmortem eyes and its variations provide a unique view of the anterior segment structures and surgical manipulations that are not readily seen during surgical procedures or by clinical inspection. It is particularly useful in studying and teaching anterior segment surgery, especially cataract and intraocular lens (IOL) surgery. We summarize the peer-reviewed literature on the use of this technique (1) in experimental studies with fresh human or animal eyes to analyze new IOLs and surgical techniques, (2) in formalin-fixed human pseudophakic autopsy eyes to study IOL-related complications, and (3) for teaching and training purposes. PMID:19251153
Isolated horizontal positional nystagmus from a posterior fossa lesion.
Lee, Hyo-Jeong; Kim, Eun Soo; Kim, Minbum; Chu, Hosuk; Ma, Hyeo-Il; Lee, Joong Seob; Koo, Ja-Won; Kim, Hyung-Jong; Hong, Sung Kwang
2014-12-01
Isolated vertigo with horizontal positional nystagmus as an impending sign of a central lesion has rarely been reported. Here we present neuro-otologic findings of patients with these clinical signs. Lesion overlays from 6 patients with ageotropic positional nystagmus revealed that the nodulus and vermis are common areas of injury. In contrast, 2 patients with geotropic positional nystagmus had cerebellar peduncle and lateral medullary lesions. These clinical findings suggest that vertigo with horizontal positional nystagmus, even in the absence of other initial neurological signs, may indicate a posterior fossa lesion, including that in the nodulus, vermis, and deep cerebellar structures. PMID:25362860
Echocardiographic Manifestation of Esophagitis Mimicking a Posterior Mediastinal Mass
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
Posterior reversible encephalopathy syndrome in intensive care medicine
Giuseppe Servillo; Francesca Bifulco; Edoardo De Robertis; Ornella Piazza; Pasquale Striano; Fabio Tortora; Salvatore Striano; Rosalba Tufano
2007-01-01
Background Posterior reversible encephalopathy syndrome (PRES) is a well-recognized clinico-neuroradiological transient condition. Early\\u000a recognition is of paramount importance for prompt control of blood pressure or removal of precipitating factors and treatment\\u000a of epileptic seizures or status epilepticus. Delay in the diagnosis and treatment may in fact results in death or in irreversible\\u000a neurological sequelae.\\u000a \\u000a \\u000a \\u000a Discussion PRES is characterized by headache, altered mental status,
Application of sonography for evaluation of posterior circulation disorders.
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
Diffuse Cerebral Vasospasm After Resection of a Posterior Fossa Ependymoma
Jeffrey T. Jacob; Christopher H. Hunt; Eelco F. Wijdicks; Alejandro A. Rabinstein; Harry Cloft; Michael J. Link
2011-01-01
Background Diffuse cerebral vasospasm after brain tumor resection is rare. This is the first report of diffuse cerebral vasospasm following\\u000a resection of a posterior fossa ependymoma. Various etiologies as to the cause of vasospasm after brain tumor resection have\\u000a been described. A review of the current literature and pathophysiology is discussed.\\u000a \\u000a \\u000a \\u000a \\u000a Methods Case report.\\u000a \\u000a \\u000a \\u000a Results A 23-year-old man developed diffuse cerebral vasospasm 12
Xing M. Wang
2009-10-15
In this paper, we continue to explore the consistence and usability of Probability Bracket Notation (PBN) proposed in our previous articles. After a brief review of PBN with dimensional analysis, we investigate probability spaces in terms of PBN by introducing probability spaces associated with random variables (R.V) or associated with stochastic processes (S.P). Next, we express several important properties of conditional expectation (CE) and some their proofs in PBN. Then, we introduce martingales based on sequence of R.V or based on filtration in PBN. In the process, we see PBN can be used to investigate some probability problems, which otherwise might need explicit usage of Measure theory. Whenever applicable, we use dimensional analysis to validate our formulas and use graphs for visualization of concepts in PBN. We hope this study shows that PBN, stimulated by and adapted from Dirac notation in Quantum Mechanics (QM), may have the potential to be a useful tool in probability modeling, at least for those who are already familiar with Dirac notation in QM.
Wang, Xing M
2007-01-01
In this paper, we continue to explore the consistence and usability of Probability Bracket Notation (PBN) proposed in our previous articles. After a brief review of PBN with dimensional analysis, we investigate probability spaces in terms of PBN by introducing probability spaces associated with random variables (R.V) or associated with stochastic processes (S.P). Next, we express several important properties of conditional expectation (CE) and some their proofs in PBN. Then, we introduce martingales based on sequence of R.V or based on filtration in PBN. In the process, we see PBN can be used to investigate some probability problems, which otherwise might need explicit usage of Measure theory. Whenever applicable, we use dimensional analysis to validate our formulas and use graphs for visualization of concepts in PBN. We hope this study shows that PBN, stimulated by and adapted from Dirac notation in Quantum Mechanics (QM), may have the potential to be a useful tool in probability modeling, at least for those...
On classical finite probability theory as a quantum probability calculus
David Ellerman
2015-02-03
This paper shows how the classical finite probability theory (with equiprobable outcomes) can be reinterpreted and recast as the quantum probability calculus of a pedagogical or "toy" model of quantum mechanics over sets (QM/sets). There have been four previous attempts to develop a quantum-like model with the base field of $\\mathbb{C}$ replaced by $\\mathbb{Z}_{2}$, but they are all forced into a merely "modal" interpretation by requiring the brackets to take values in $\\mathbb{Z}_{2}$ (1 = possible, 0 = impossible). But the usual QM brackets give the "overlap" between states {\\psi} and {\\phi}, so for subsets S,T of U, the natural definition is $=|S{\\cap}T|$. This allows QM/sets to be developed with a full probability calculus that turns out to be the perfectly classical Laplace-Boole finite probability theory. The point is not to clarify finite probability theory but to elucidate quantum mechanics itself by seeing some of its quantum features (e.g., two-slit experiment) in a classical setting.
Maximum entropy principle and partial probability weighted moments
NASA Astrophysics Data System (ADS)
Deng, Jian; Pandey, M. D.; Xie, W. C.
2012-05-01
Maximum entropy principle (MaxEnt) is usually used for estimating the probability density function under specified moment constraints. The density function is then integrated to obtain the cumulative distribution function, which needs to be inverted to obtain a quantile corresponding to some specified probability. In such analysis, consideration of higher ordermoments is important for accurate modelling of the distribution tail. There are three drawbacks for this conventional methodology: (1) Estimates of higher order (>2) moments from a small sample of data tend to be highly biased; (2) It can merely cope with problems with complete or noncensored samples; (3) Only probability weighted moments of integer orders have been utilized. These difficulties inevitably induce bias and inaccuracy of the resultant quantile estimates and therefore have been the main impediments to the application of the MaxEnt Principle in extreme quantile estimation. This paper attempts to overcome these problems and presents a distribution free method for estimating the quantile function of a non-negative randomvariable using the principle of maximum partial entropy subject to constraints of the partial probability weighted moments estimated from censored sample. The main contributions include: (1) New concepts, i.e., partial entropy, fractional partial probability weighted moments, and partial Kullback-Leibler measure are elegantly defined; (2) Maximum entropy principle is re-formulated to be constrained by fractional partial probability weighted moments; (3) New distribution free quantile functions are derived. Numerical analyses are performed to assess the accuracy of extreme value estimates computed from censored samples.
Techniques for determining probabilities of geologic events and processes
Hunter, R.L. (ed.) (Sandia National Labs., Albuquerque, NM (United States)); Mann, C.J. (ed.) (Illinois Univ., Urbana, IL (United States))
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.
Techniques for determining probabilities of geologic events and processes
Hunter, R.L. [ed.] [Sandia National Labs., Albuquerque, NM (United States); Mann, C.J. [ed.] [Illinois Univ., Urbana, IL (United States)
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.
CHSH Inequality: Quantum Probabilities as Classical Conditional Probabilities
NASA Astrophysics Data System (ADS)
Khrennikov, Andrei
2015-07-01
In this note we demonstrate that the results of observations in the EPR-Bohm-Bell experiment can be described within the classical probabilistic framework. However, the "quantum probabilities" have to be interpreted as conditional probabilities, where conditioning is with respect to fixed experimental settings. Our approach is based on the complete account of randomness involved in the experiment. The crucial point is that randomness of selections of experimental settings has to be taken into account within one consistent framework covering all events related to the experiment. This approach can be applied to any complex experiment in which statistical data are collected for various (in general incompatible) experimental settings.
Is ossification of posterior longitudinal ligament an enthesopathy?
Chen, Jian; Song, Dianwen; Wang, Xinwei; Shen, Xiaolong; Li, Yang; Yuan, Wen
2011-10-01
The purpose of this study was to investigate the relationship of ossification of posterior longitudinal ligament (OPLL) with enthesis, the site where the posterior longitudinal ligament (PLL) attaches to the vertebral body, by multi-detector CT reconstruction images. Twenty-nine patients with OPLL were studied. According to the plaques' continuity to the vertebral body, OPLL plaques were classified into two categories: "free" and "contiguous". A "broken sign" was defined as a crack between two plaques. The sites where each "contiguous" plaque attached to the vertebral body were then analysed. There were 78 ossified plaques in total, and six were "free". There were eight cases with a "broken sign", including six "free" ones. The site where all 72 "contiguous" plaques attached to the vertebral body included the zone where the PLL enthesis was situated, while other zones were included in only part of the plaques. Our conclusion was that there might be no real "free type" ossified plaques, and OPLL could start from enthesis, which indicated OPLL could be a kind of enthesopathy. PMID:21104248
Glue-assisted intrascleral fixation of posterior chamber intraocular lens
Narang, Priya; Narang, Samir
2013-01-01
Purpose: To analyze the visual outcome of patients undergoing glue-assisted intrascleral fixation of posterior chamber intraocular lens (IOL) in the absence of posterior capsular support. Materials and Methods: This retrospective study analyzes 25 eyes which underwent IOL implantation by the glued intrascleral fixation technique. The pre and post-operative uncorrected visual acuity (UCVA), pre and post-operative best corrected visual acuity (BCVA), intraocular pressure (IOP), IOL position, anterior chamber reaction and central macular thickness were assessed and recorded. Immediate and late post-operative complications were also recorded. Results: A total of 25 eyes of 22 patients were reviewed and analyzed over a period of one year. All eyes had a foldable three-piece IOL implanted. About 84% of the eyes had a gain of one or more lines, 12% had no gain, and 4% had a fall of three lines of BCVA on Snellen's visual chart, which was attributed to cystoid macular edema (CME). Postoperatively, there was a significant improvement in the UCVA (P < 0.05) and in the BCVA (P < 0.05). Postoperative complications included decentration in one case and vitritis with chronic macular edema in another case. Optical coherence tomography (OCT) demonstrated well placed IOL with no tilt. Conclusion: Although the results of one year follow-up of glued intrascleral fixation are promising, long term studies are recommended. PMID:23685487
The web lift and posterior pull for the aging face.
Ezzat, Waleed H; Andretto Amodeo, Chiara; Keller, Gregory S
2012-02-01
There are many factors that contribute to the aging neck. We have recently begun employing a percutaneous suture spanning the submentum combined with a posterior platysma pull. We present our initial results with this technique. In this retrospective study, subjects underwent the combined procedure with and without concomitant rhytidectomy. Cephalometric analysis was used to compare the preoperative cervicomental angle (CMA) and hyomental distance (HMD) with postoperative values at 4 weeks. Subjects also were queried on their postoperative satisfaction. Twenty-five subjects were included in this study. At 4 weeks postoperatively, we achieved significant reductions in the average CMA (134.8 versus 122.8, p = 0.002). The postoperative HMD significant increased an average of 1.9 cm (8.5 versus 10.4, p = 0.009). We achieved a 92.3% satisfaction score at 33 weeks (range = 25 to 44). The combination of a percutaneous suture across the submentum and a posterior platysma pull is a safe and effective method of addressing the many facets of the aging neck. Our initial results are easily reproducible and entail minimal morbidity to the patient. PMID:22418822
Non-traumatic posterior atlanto-occipital joint dislocation.
Takechi, Yasuhiko; Iizuka, Haku; Sorimachi, Yasunori; Ara, Tsuyoshi; Nishinome, Masahiro; Takagishi, Kenji
2011-07-01
This report presents a case of non-traumatic posterior atlanto-occipital dislocation. A 36-year-old female was referred with a history of numbness of the extremities, vertigo and neck pain for 1 year. The patient had no history of trauma. The axial rotation of range of motion of the cervical spine was severely restricted. A lateral cervical radiograph in the neutral position demonstrated a posterior atlanto-occipital dislocation. A coronal view on a computed tomography (CT) reconstruction image showed a loss of angle of the bilateral atlanto-occipital joint, and a sagittal reconstruction view of CT images also demonstrated flatness of atlanto-occipital joint. Instrumented occipito-cervical fusion was performed after reduction. A lateral cervical radiograph in the neutral position 1 year after surgery showed the reduction of atlanto-occipital joint, moreover, it was maintained even in an extended position. The patient had neurologic improvement after surgery. Flatness of the bilateral atlanto-occipital joint may have induced this instability. Occipital-cervical fusion was chosen in the present case since the patient showed restricted axial rotation of the neck before surgery. The surgery improved the preoperative symptoms including the function of cervical spine evaluated by JOACMEQ. PMID:20549257
Distinct Value Signals in Anterior and Posterior Ventromedial Prefrontal Cortex
Smith, David V.; Hayden, Benjamin Y.; Truong, Trong-Kha; Song, Allen W.; Platt, Michael L.; Huettel, Scott A.
2010-01-01
The core feature of an economic exchange is a decision to trade one good for another, based on a comparison of relative value. Economists have long recognized, however, that the value an individual ascribes to a good during decision making (i.e., their relative willingness to trade for that good) does not always map onto the reward they actually experience. Here, we show that experienced value and decision value are represented in distinct regions of ventromedial prefrontal cortex (VMPFC) during the passive consumption of rewards. Participants viewed two categories of rewards – images of faces that varied in their attractiveness and monetary gains and losses – while being scanned using functional magnetic resonance imaging (fMRI). An independent market task, in which participants exchanged some of the money that they earned for brief views of attractive faces, determined the relative decision value associated with each category. We found that activation of anterior VMPFC increased with increasing experienced value, but not decision value, for both reward categories. In contrast, activation of posterior VMPFC predicted each individual's relative decision value for face and monetary stimuli. These results indicate not only that experienced value and decision value are represented in distinct regions of VMPFC, but also that decision value signals are evident even in the absence of an overt choice task. These results endorse the idea that decisions are made by comparing neural representations of the value of different goods encoded in posterior VMPFC in a common, relative currency. PMID:20164333
Laparoscopic hiatal herniorrhaphy with posterior fundoplication for gastroesophageal reflux.
Barr, L L
1998-12-01
Complications and side effects following laparoscopic antireflux procedures are common. This article describes an alternative laparoscopic technique to prevent gastroesophageal reflux. This method consists of posterior approximation of the diaphragmatic crura followed by a posterior fundoplication of approximately 270 degrees wrap. In avoiding the 360 degree wrap and obtaining length from the longitudinal axis of the stomach, it is not necessary to take down the gastrosplenic vessels. The principle of the procedure is to accentuate the cardioesophageal angle of His. No sutures are placed in the esophagus. While this article primarily concerns technique, it also constitutes a brief report on the first 50 patients who have been followed up for 1 year or more. All patients but one are free of reflux symptoms and have discontinued taking all medication. There has been no dysphagia to liquids, and solid food dysphagia has not lasted >1 month. Bloating from gas is minimal, as most patients are able to burp early in their recovery. An outcome paper describing preoperative and postoperative objective testing and evaluation is in process. PMID:9864104
Posterior Fossa Neurenteric Cysts Can Expand Rapidly: Case Report
Priamo, Francesco A.I.; Jimenez, Elpidio D.; Benardete, Ethan A.
2011-01-01
Neurenteric cysts are considered congenital lesions that may slowly expand over time. Although more commonly found in the spinal canal, they may be found intracranially, particularly in the posterior fossa. Here, we present an unusual case of a large, rapidly expanding histologically confirmed posterior fossa neurenteric cyst in a 53-year-old woman, who presented with quadriparesis. Computed tomography imaging done ~1.5 years before admission failed to demonstrate any obvious abnormality; however, the lesion had grown to 4 cm in maximal dimension at presentation with significant mass effect. The lesion was resected microsurgically using a retrosigmoid approach. The patient improved postoperatively and was neurologically intact at last follow-up. We could find no other documented case of marked, rapid expansion of a neurenteric cyst in the literature. We conclude that, although neurenteric cysts are thought to be congenital, they can undergo rapid expansion even in adults. The mechanism of expansion is unknown but may involve increased secretion, hemorrhage, or inflammation. We discuss the surgical management and review the literature in view of this surprising finding. PMID:23984213
Human posterior parietal cortex mediates hand-specific planning.
Valyear, Kenneth F; Frey, Scott H
2015-07-01
The processes underlying action planning are fundamental to adaptive behavior and can be influenced by recent motor experience. Here, we used a novel fMRI Repetition Suppression (RS) design to test the hypotheses that action planning unfolds more efficiently for successive actions made with the same hand. More efficient processing was predicted to correspond with both faster response times (RTs) to initiate actions and reduced fMRI activity levels - RS. Consistent with these predictions, we detected faster RTs for actions made with the same hand and accompanying fMRI-RS within bilateral posterior parietal cortex and right-lateralized parietal operculum. Within posterior parietal cortex, these RS effects were localized to intraparietal and superior parietal cortices. These same areas were more strongly activated for actions involving the contralateral hand. The findings provide compelling new evidence for the specification of action plans in hand-specific terms, and indicate that these processes are sensitive to recent motor history. Consistent with computational efficiency accounts of motor history effects, the findings are interpreted as evidence for comparatively more efficient processing underlying action planning when successive actions involve the same versus opposite hand. PMID:25842294
Posterior Cerebral Artery Insufficiency in Pediatric Moyamoya Disease
Lee, Ji Yeoun; Kim, Seung-Ki; Phi, Ji Hoon
2015-01-01
The majority of clinical studies on moyamoya disease (MMD) have focused on anterior circulation. The disease involvement of posterior circulation in MMD, mainly in the posterior cerebral artery (PCA), has been mentioned since the early 1980s, and it has been repeatedly emphasized as one of the most important factors related to poor prognosis in MMD. However, its clinical features and outcome have only been elucidated during the last few years. In this review, the angiographic definition of PCA stenosis is summarized. The clinical features are elucidated as being either early-onset or delayed-onset, according to the time of PCA stenosis diagnosis in reference to the anterior circulation revascularization surgeries. The surgical strategy and hypothesis on the mechanism of PCA stenosis is also briefly mentioned. It appears that some MMD patients may show PCA stenosis during the early or late course of the disease and that the presenting symptoms may vary. Because the hemodynamic compromise caused by PCA stenosis may respond well to surgical treatment, clinicians should be aware of the condition, especially during follow-up of MMD patients. PMID:26180612
Recurrent Posterior Strokes in Inflammatory Bowel Disease Patients
Hymel, Brett; Chavez-Keatts, Maria; Karlitz, Jordan J.; Martin-Schild, Sheryl
2015-01-01
Objective. To describe the stroke characteristics of patients with a history of inflammatory bowel disease (IBD). Background. A hypercoagulable state associated with IBD has been frequently implicated as a risk factor for ischemic stroke. Variable mechanisms and infrequent occurrence limit prospective clinical research on the association between IBD and stroke. Methods. We retrospectively reviewed consecutive patients with acute ischemic stroke presenting to our medical center from 7/2008 to 9/2013. Patients with a history of IBD were identified. Clinical variables were abstracted from our prospective stroke registry. Results. Over the period of five years we identified only three patients with a documented history of IBD. Each of these patients presented three times to our hospital with new strokes. Patients presented outside the window for intravenous tPA treatment on 8/9 admissions. Each one of our patients had posterior strokes on at least two separate occasions. Hypercoagulation panel showed elevated factor VIII with or without concomitant elevation of Von Willebrand factor (vWF) during almost every admission (8/9 admissions). Only one admission was associated with IBD flare. Conclusion. The association between IBD and posterior strokes is a novel finding. Factor VIII elevation may serve as a biomarker of a peristroke hypercoagulable state in patients with IBD. PMID:25784930
Posterior Cervical Inclinatory Foraminotomy for Spondylotic Radiculopathy Preliminary
Chang, Jae-Chil; Choi, Soon-Kwan
2011-01-01
Posterior cervical foraminotomy is an attractive therapeutic option in selected cases of cervical radiculopathy that maintains cervical range of motion and minimize adjacent-segment degeneration. The focus of this procedure is to preserve as much of the facet as possible with decompression. Posterior cervical inclinatory foraminotomy (PCIF) is a new technique developed to offer excellent results by inclinatory decompression with minimal facet resection. The highlight of our PCIF technique is the use of inclinatory drilling out for preserving more of facet joint. The operative indications are radiculopathy from cervical foraminal stenosis (single or multilevel) with persistent or recurrent root symptoms. The PCIFs were performed between April 2007 and December 2009 on 26 male and 8 female patients with a total of 55 spinal levels. Complete and partial improvement in radiculopathic pain were seen in 26 patients (76%), and 8 patients (24%), respectively, with preserving more of facet joint. We believe that PCIF allows for preserving more of the facet joint and capsule when decompressing cervical foraminal stenosis due to spondylosis. We suggest that our PCIF technique can be an effective alternative surgical approach in the management of cervical spondylotic radiculopathy. PMID:21716632
Novel Classification of the Posterior Auricular Artery Based on Angiographical Appearance
Tokugawa, Joji; Cho, Narisumi; Suzuki, Hiroharu; Sugiyama, Natsuki; Akiyama, Osamu; Nakao, Yasuaki; Yamamoto, Takuji
2015-01-01
Purpose To investigate the length variation of the posterior auricular artery and propose a novel classification of the posterior auricular artery based on angiographical appearance. Patients and Methods A series of 234 consecutive patients who had undergone conventional cerebral angiography was analyzed. The posterior auricular artery was examined on the lateral projection of the external carotid or common carotid arteriography. The posterior auricular artery was classified into four groups by length, using the external auditory canal and the top of the helix as radiographical landmarks. Our proposed classification is as follows: Type A, posterior auricular artery terminates between its origin and the center of the external auditory canal; Type B, posterior auricular artery terminates between the center of the external auditory canal and the top of the helix; Type C, posterior auricular artery terminates between the top of the helix and the vertex; and Type D, posterior auricular artery reaches up to the vertex. Results A total of 424 (right, 214; left, 210) posterior auricular arteries were analyzed in 111 men and 123 women aged 11 to 91 years (mean, 61.0 years) examined for aneurysms in 78 cases, occlusive vascular diseases in 56, intracranial hemorrhages in 41, tumors in 35, and others in 24. Types A, B, C, and D were found in 15.1%, 34.9%, 48.8%, and 1.2% of the patients, respectively. Conclusion A novel classification of the posterior auricular artery identifies four types based on its length on cerebral angiography. PMID:26030595
Lu, Daifeng; Xiao, Mochao; Lian, Yongyun; Zhou, Yong; Liu, Xuefeng
2014-01-01
Objective: To perform dual-bundle reconstruction of posterior cruciate ligament using full arthroscopic tibial inlay technology with self-designed tibia tunnel drilling system and to compare the effect of arthroscopic tibial inlay versus traditional technique for posterior cruciate ligament reconstruction. Material and methods: 32 patients were randomly divided into experiment group (improved tibial inlay, n = 17) and control group (traditional tibial inlay, n = 15). Self-designed tibia tunnel drill system was used to produce intraoperative deep-limited bone tunnel. During follow-up, the location of the bone block and the healing situation were checked by knee X-ray and spiral CT scan. Blood loss, operation time and nerve vascular injuries were evaluated. Results: Mean intraoperative blood loss was 123.53 ± 74.05 ml in the improved tibial inlay group compared with 332 ± 114.26 ml in the traditional tibial inlay group (t = 6.12, P < 0.05). Mean operation time was 235.27 ± 58.88 min in the improved tibial inlay group compared with 346.37 ± 59.67 min in the traditional tibial inlay group (t = 5.19, P < 0.05). Posterior drawer test were negative in 15 cases, slight positive in 2 with improved tibial inlay technique compared with 14 negative cases and 2 positive cases of traditional tibial Inlay technique. The X-ray and spiral CT scan showed the location of the bone block were perfect and healed well with the patent who received improved tibial inlay technology after 12 weeks postoperatively. Conclusion: Accurate depth-limited bone tunnel can be produced by the tibia tunnel drill system with minor trauma, less bleeding and reducing of nerves or vessels and the recent clinical effects of PCL reconstruction were pretty good. PMID:25419349
[Posterior cortical atrophy : Pathology, diagnosis and treatment of a rare form of dementia].
Ortner, M; Kurz, A
2015-07-01
The syndrome of posterior cortical atrophy (PCA) is a rare clinical manifestation of several neurodegenerative diseases which affect the parieto-occipital cortex. The most frequent underlying pathology is Alzheimer's disease but some cases are caused by Lewy body disease, progressive subcortical gliosis, corticobasal degeneration or prion diseases. The most prominent clinical feature of PCA is complex visual disturbances including object agnosia, simultanagnosia, optical ataxia and oculomotor apraxia while basic visual functions remain intact. These deficits lead to multiple impairments in activities of daily living that require visual control. On progression of the disease amnestic, apraxic and dysexecutive symptoms occur so that a global dementia gradually emerges. At the core of the diagnostic work-up are a detailed patient history, accurate analysis of behavior and neuropsychological testing. Structural and functional brain imaging are suitable to demonstrate the localization of the disease process. Measurement of cerebrospinal fluid proteins (e.g. beta amyloid, tau, phospho-tau and 14-3-3) serves to confirm or exclude Alzheimer's disease or prion diseases. The mainstay of treatment are non-pharmacological interventions to support activities of daily living and personal independence. These treatments include cognitive training and compensatory strategies which can be prescribed as neuropsychological treatment or occupational therapy. If Alzheimer's disease or Lewy body disease is the likely cause, a treatment with cholinesterase inhibitor may be tried. Caregiver education and support are another essential part of the treatment regimen as with all forms of dementia. PMID:25791802
Primary and submovement control of aiming in C6 tetraplegics following posterior deltoid transfer
2014-01-01
Background Upper limb motor control in fast, goal-directed aiming is altered in tetraplegics following posterior-deltoid musculotendinous transfer. Specifically, movements have similar end-point accuracy but longer duration and lower peak velocity than those of age-matched, neurotypical controls. Here, we examine in detail the interplay between primary movement and submovement phases in five C6 tetraplegic and five control participants. Methods Aiming movements were performed in two directions (20 cm away or toward), with or without vision. Trials that contained a submovement phase (i.e., discontinuity in velocity, acceleration or jerk) were identified. Discrete kinematic variables were then extracted on the primary and submovements phases. Results The presence of submovements did not differ between the tetraplegic (68%) and control (57%) groups, and almost all submovements resulted from acceleration and jerk discontinuities. Tetraplegics tended to make a smaller amplitude primary movement, which had lower peak velocity and greater spatial variability at peak velocity. This was followed by a larger amplitude and longer duration secondary submovement. Peak velocity of primary movement was not related to submovement incidence. Together, the primary and submovement phases of both groups were equally effective in reducing end-point error. Conclusions C6 tetraplegic participants exhibit some subtle differences in measures of motor behaviour compared to control participants, but importantly feedforward and feedback processes work effectively in combination to achieve accurate goal-directed aiming. PMID:25055852
Three-year follow-up of five posterior composites: in vivo wear.
Willems, G; Lambrechts, P; Braem, M; Vanherle, G
1993-04-01
The wear of five posterior composites at occlusal contact areas (OCA) and contact free occlusal areas (CFOA) was evaluated in Class II cavities over a 3-year period with an accurate 3D-measuring technique. A clinical evaluation was also performed. The ultrafine compact-filled composites (Willems et al., 1992) showed acceptable OCA-wear rates ranging from 110 to 149 microns after 3 years. This is very similar to the OCA-wear rate of human enamel on molars, which is about 122 microns after 3 years. The fine compact-filled composite had an unacceptable OCA-wear value of 242 microns after 3 years. The ultrafine midway-filled composite showed an exceptionally high CFOA-wear value of 151 microns after 3 years, which gave the impression of it being gradually washed out of the cavity. Clinically, 70% of the restorations made with the ultrafine midway-filled composite showed excellent colour match after 3 years. For most of the compact-filled composites slightly opaque fillings were noted and 63% of the restorations made with one of these materials were clearly opaque. It can be concluded that the investigated ultrafine compact-filled composites can be considered as amalgam alternatives as far as their wear resistance is concerned. PMID:8473595
Obtaining accurate measurement using redundant sensors
Burnett, Michael Scott
1996-01-01
Conventional wisdom suggests to accomplish accurate measurement, the sensors used must have high precision and excellent dynamic range. This generally results in sensor systems that are complex, costly, and often sensitive to environmental factors...
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.
Continuous Probability 2.1 Simulation of Continuous Probabilities
Rapaport, Iván
PROBABILITY DENSITIES 0 x Figure 2.1: A spinner. To simulate this experiment on a computer is an easy matter In this section we shall show how we can use computer simulations for experiments that have a whole continuum counterclockwise. The experiment consists of spinning the pointer and recording the label of the point at the tip
Dynamical origin of quantum probabilities
NASA Astrophysics Data System (ADS)
Valentini, Antony; Westman, Hans
2005-01-01
We study the origin of the Born probability rule ? = |?|2 in the de Broglie-Bohm pilot-wave formulation of quantum theory. It is argued that quantum probabilities arise dynamically, and have a status similar to thermal probabilities in ordinary statistical mechanics. This is illustrated by numerical simulations for a two-dimensional system. We show that a simple initial ensemble, with a non-standard distribution ? ? |?|2 of particle positions, evolves towards the quantum distribution to high accuracy. The relaxation process ? ? |?|2 is quantified in terms of a coarse-grained H-function (equal to minus the relative entropy of ? with respect to |?|2), which is found to decrease approximately exponentially over time, with a time constant that accords with a simple theoretical estimate.
Learning Resources: Statistics: Non-Probability Sampling
NSDL National Science Digital Library
Legge, Joe Anne
This is website, presented by Statistics Canada, examines the concept of non-probability sampling. It discusses types of non-probability sampling, differences between probability and non-probability sampling, and provides examples of non-probability sampling. Links to other topics related to sampling methods, bias, and exercise activities are also provided.
hp calculators HP 50g Probability distributions
Vetter, Frederick J.
hp calculators HP 50g Probability distributions The MTH (MATH) menu Probability distributions Practice solving problems involving probability distributions #12;hp calculators HP 50g Probability distributions hp calculators - 2 - HP 50g Probability distributions The MTH (MATH) menu The Math menu
Lindå, Hans; von Heijne, Anders
2015-01-01
We describe posterior reversible encephalopathy syndrome (PRES) in a woman with multiple sclerosis treated with Gilenya® (Fingolimod). The first symptoms appeared after 21?months of fingolimod treatment. She experienced headache, altered mental status, cognitive deficits, seizures, and visual disturbances. Not at any time during the course of the disease could any signs of infection or rheumatic disorder be detected. Test for anti-neuronal antibodies was also negative. Her blood pressure was normal. MRI showed widespread cortical and subcortical changes with some mass-effect in the temporo-occipital-parietal lobes in the left hemisphere. Contrast enhancement was seen in the leptomeninges and, in addition, there were no areas with restricted diffusion and no signs of hemorrhage. Her condition deteriorated until fingolimod was discontinued. Slowly her condition improved and after 8?months, the only symptoms that remained were two small, non-corresponding, right inferior scotomas. We believe that all symptoms, the clinical course, and the MRI findings in this case can all be explained by considering PRES, a probably rare, but serious, side effect of fingolimod treatment. PMID:25788891
Heinrichs, Kristinn I.; Lachowicz, Wendy M.; Detmer, Don E.
2000-01-01
Objective: Exercise-induced leg pain may be triggered by abnormally high compartment pressure. In addition to the more widely publicized anterior compartment syndrome, the deep posterior compartment syndrome can just as frequently occur, resulting in severe pain and disability due to muscle and nerve ischemia. Background: Obtaining a thorough history and compartmental pressure measurements are the usual components in the accurate diagnosis of compartment syndromes. While few other disorders mimic compartment syndromes, differential diagnoses must be considered. Surgical management of deep compartment syndrome, consisting of fasciotomy or fasciectomy, or both, is successful for most patients. Differential Diagnosis: Tibial stress fracture or microfracture, tibial periostitis, tibial periostalgia, distal deep posterior chronic compartment syndrome, proximal deep chronic compartment syndrome, superficial lateral compartment syndrome, deep venous thrombosis, popliteal artery entrapment, or chronic compartment syndrome. Uniqueness: Chronic deep compartment syndrome is one of the most common causes of exercise-induced leg pain in aerobic athletes. Therefore, the athletic trainer must be able to recognize the condition. Signs, symptoms, diagnosis, and surgical management of chronic deep compartment syndrome, chronic periostalgia, and superficial lateral compartment syndrame in a 21-year-old Division IA track and field athlete are presented. Conclusions: With the correct diagnosis, persistent and methodical reevaluation, and appropriate management, the athlete can expect a successful treatment outcome. PMID:16558661
Fusion Probability in Dinuclear System
Juhee Hong
2015-03-26
Fusion can be described by the time evolution of a dinuclear system with two degrees of freedom, the relative motion and transfer of nucleons. In the presence of the coupling between two collective modes, we solve the Fokker-Planck equation in a locally harmonic approximation. The potential of a dinuclear system has the quasifission barrier and the inner fusion barrier, and the escape rates can be calculated by the Kramers' model. To estimate the fusion probability, we calculate the quasifission rate and the fusion rate. We investigate the coupling effects on the fusion probability and the cross section of evaporation residue.
Interference of probabilities in dynamics
Zak, Michail, E-mail: michail.zak@gmail.com [Jet Propulsion Laboratory California Institute of Technology, Pasadena, CA 91109 (United States)
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.
Simon Saunders
2001-12-14
Special relativity is most naturally formulated as a theory of space-time geometry, but within the space-time framework probability apears to be at best an epistemic notion - a matter of what can be known, not of the status of events in themselves. However, a non-epistemic account of probability can be given in Minkowski space-time, in terms of the Everett interpretation. We work throughout in the consistent histories formalism, first in tems of a single history, and then using many
Craig, A.D. (Bud)
2014-01-01
Prior anterograde tracing work identified somatotopically organized lamina I trigemino- and spino-thalamic terminations in a cytoarchitectonically distinct portion of posterolateral thalamus of the macaque monkey, named the posterior part of the ventral medial nucleus (VMpo; Craig, 2004b). Microelectrode recordings from clusters of selectively thermoreceptive or nociceptive neurons were used to guide precise micro-injections of various tracers in VMpo. A prior report (Craig and Zhang, 2006) described retrograde tracing results, which confirmed the selective lamina I input to VMpo and the antero-posterior (head to foot) topography. The present report describes the results of micro-injections of anterograde tracers placed at different levels in VMpo, based on the antero-posterior topographic organization of selectively nociceptive units and clusters over nearly the entire extent of VMpo. Each injection produced dense, patchy terminal labeling in a single coherent field within a distinct granular cortical area centered in the fundus of the superior limiting sulcus. The terminations were distributed with a consistent antero-posterior topography over the posterior half of the superior limiting sulcus. These observations demonstrate a specific VMpo projection area in dorsal posterior insular cortex that provides the basis for a somatotopic representation of selectively nociceptive lamina I spinothalamic activity. These results also identify the VMpo terminal area as the posterior half of interoceptive cortex; the anterior half receives input from the vagal-responsive and gustatory neurons in the basal part of the ventral medial nucleus (VMb). PMID:23853108
Xenopus Tbx6 mediates posterior patterning via activation of Wnt and FGF signalling.
Lou, Xin; Fang, Panfeng; Li, Shuangwei; Hu, Rui-Ying; Kuerner, Klaus-Michael; Steinbeisser, Herbert; Ding, Xiaoyan
2006-09-01
In vertebrates, the patterning of anterior-posterior (AP) axis is a fundamental process during embryogenesis. Wnt and FGF signalling pathways play important roles in regulating the patterning of embryo AP axis. Mouse Tbx6 encodes a transcription factor that has been demonstrated to be involved in the specification of the posterior tissue in mouse embryonic body. Here, we prove that morpholino-induced knockdown of XTbx6 impairs posterior development, indicating the requirement of XTbx6 in this process. Meanwhile, gain of XTbx6 function is sufficient to induce ectopic posterior structures in Xenopus embryos. Furthermore, XTbx6 activates the expression of Xwnt8 and FGF8, which are two mediators of posterior development, suggesting a mechanism by which XTbx6 modulates posterior patterning via Wnt and FGF signalling pathway activation. PMID:16953215
Jaremko, J L; Jans, L B O; Coleman, L T; Ditchfield, M R
2010-10-01
DWI reportedly accurately differentiates pediatric posterior fossa tumors, but anecdotal experience suggests limitations. In 3 years, medulloblastoma and JPA were differentiated by DWI alone in 23/26 cases (88%). Ependymoma (n = 5) could not be reliably differentiated from medulloblastoma or JPA. A trend toward increased diffusion restriction in higher grade tumors (1/14 grade I, 7%; 9/12 grade IV, 75%) had too much overlap to predict the grade of individual cases. The overlap in ADC between tumor types appeared partly due to technical factors (in small, heterogeneous, calcific, or hemorrhagic tumors) but also likely reflected true histologic variability, given that our 3 overlap cases included a desmoplastic medulloblastoma, an anaplastic ependymoma, and a JPA with restricted diffusion in its nodule. Simple structural features (macrocystic tumor, location off midline) aided in distinguishing JPA from the other tumors in these cases. PMID:20538820
NASA Astrophysics Data System (ADS)
Mara, Thierry A.; Fajraoui, Noura; Younes, Anis; Delay, Frederick
2015-02-01
We introduce the concept of maximal conditional posterior distribution (MCPD) to assess the uncertainty of model parameters in a Bayesian framework. Although, Markov Chains Monte Carlo (MCMC) methods are particularly suited for this task, they become challenging with highly parameterized nonlinear models. The MCPD represents the conditional probability distribution function of a given parameter knowing that the other parameters maximize the conditional posterior density function. Unlike MCMC which accepts or rejects solutions sampled in the parameter space, MCPD is calculated through several optimization processes. Model inversion using MCPD algorithm is particularly useful for highly parameterized problems because calculations are independent. Consequently, they can be evaluated simultaneously with a multi-core computer. In the present work, the MCPD approach is applied to invert a 2D stochastic groundwater flow problem where the log-transmissivity field of the medium is inferred from scarce and noisy data. For this purpose, the stochastic field is expanded onto a set of orthogonal functions using a Karhunen-Loève (KL) transformation. Though the prior guess on the stochastic structure (covariance) of the transmissivity field is erroneous, the MCPD inference of the KL coefficients is able to extract relevant inverse solutions.
Michael J. Anderson; David L. Becker; Travis Kieckbusch
2002-01-01
We conducted a retrospective review of 2 consecutive series of posterior-stabilized total knee arthroplasties (TKAs) to evaluate patellofemoral complications, in particular, significant patellofemoral crepitance or patellar clunk syndrome. Twenty posterior-stabilized Axiom PSK (Wright Medical Technology, Arlington, TN) TKAs (group 1) were compared with 20 posterior cruciateNsacrificed Advance medial pivot (Wright Medical Technology, Arlington, TN) TKAs (group 2). The average age
Intersymbol interference and error probability
M. Aaron; D. Tufts
1966-01-01
Using a criterion of minimum average error probability we derive a method for specifying an optimum linear, time invariant receiving filter for a digital data transmission system. The transmitted data are binary and coded into pulses of shapepm s(t). The linear transmission medium introduces intersymbol interference and additive Gaussian noise. Because the intersymbol interference is not Gaussian and can be
Comments on quantum probability theory.
Sloman, Steven
2014-01-01
Quantum probability theory (QP) is the best formal representation available of the most common form of judgment involving attribute comparison (inside judgment). People are capable, however, of judgments that involve proportions over sets of instances (outside judgment). Here, the theory does not do so well. I discuss the theory both in terms of descriptive adequacy and normative appropriateness. PMID:24482328
Probability: Chances Are - Part 1
NSDL National Science Digital Library
Mathline
1997-01-01
In this 21-minute video of a third grade class, the teacher, Carolyn Bereska, guides students through an exploration of probability terms utilizing a "walk-on number line". Along with the video, there are support materials: a math lesson plan and a professional development guide.
Probability and Statistics K-6
NSDL National Science Digital Library
Craig Loewen
This webpage based on the Western Canadian Protocol for grades K-6 details activities for the seventeen objectives in the Probability and Statistics strand. Each objective links to a page that includes a problem, a manipulative activity, and a game. Some of the activities require special cards, spinners, cutouts, etc. which are provided at the bottom of the webpage in PDF format.
Probable Supernova discovered by PSST
NASA Astrophysics Data System (ADS)
Wright, D.; Smith, K. W.; Smartt, S. J.; Huber, M.; Chambers, K. C.; Flewelling, H.; Willman, M.; Primak, N.; Schultz, A.; Gibson, B.; Magnier, E.; Waters, C.; Tonry, J.; Wainscoat, R. J.; Foley, R. J.; Jha, S. W.; Rest, A.; Scolnic, D.
2015-05-01
A bright transient, which is a probable supernova, has been discovered as part of the Pan-STARRS Survey for Transients (PSST). Information on all objects discovered by the Pan-STARRS Survey for Transients is available at http://star.pst.qub.ac.uk/ps1threepi/.
Probability distributions of optical flow
Eero P. Simoncelli; Edward H. Adelson; David J. Heeger
1991-01-01
Gradient methods are widely used in the computation of optical flow. The authors discuss extensions of these methods which compute probability distributions of optical flow. The use of distributions allows representation of the uncertainties inherent in the optical flow computation, facilitating the combination with information from other sources. Distributed optical flow for a synthetic image sequence is computed, and it
Probability and Statistics David Ronis
Ronis, David M.
. Shown below, are two grade distributions for two classes taking an hourly exam in some course. How would, they have the same average grade. Fall Term, 2014 #12;Probability -2- Chemistry 223 How much information theory of gasses, a different sort of question is being asked; namely, how do the molecules move
Probability Surveys Vol. 0 (0000)
Le Gall, Jean-François
by Dyck paths. We pay special attention to random real trees coded by Brown- ian excursions trees with independent spatial motions. We introduce exit measures for the Brownian snake and we presentProbability Surveys Vol. 0 (0000) ISSN: 1549-5787 DOI: 10.1214/154957804100000000 Random Trees
Outage Probability Under Channel Distribution Uncertainty
Loyka, Sergey
Outage Probability Under Channel Distribution Uncertainty Ioanna Ioannou, Charalambos D outage probability defined as min (over the input distribution) -max (over the channel distribution class to the case of partial channel distribution information. Compound outage probability characterization via one
Cellular mechanisms of posterior neural tube morphogenesis in the zebrafish.
Harrington, Michael J; Chalasani, Kavita; Brewster, Rachel
2010-03-01
The zebrafish is a well established model system for studying neural development, yet neurulation remains poorly understood in this organism. In particular, the morphogenetic movements that shape the posterior neural tube (PNT) have not been described. Using tools for imaging neural tissue and tracking the behavior of cells in real time, we provide the first comprehensive analysis of the cellular events shaping the PNT. We observe that this tissue is formed in a stepwise manner, beginning with merging of presumptive neural domains in the tailbud (Stage 1); followed by neural convergence and infolding to shape the neural rod (Stage 2); and continued elongation of the PNT, in absence of further convergence (Stage 3). We further demonstrate that cell proliferation plays only a minimal role in PNT elongation. Overall, these mechanisms resemble those previously described in anterior regions, suggesting that, in contrast to amniotes, neurulation is a fairly uniform process in zebrafish. PMID:20077475
The subcommissural organ and the development of the posterior commissure.
Grondona, Jesús M; Hoyo-Becerra, Carolina; Visser, Rick; Fernández-Llebrez, Pedro; López-Ávalos, María Dolores
2012-01-01
Growing axons navigate through the developing brain by means of axon guidance molecules. Intermediate targets producing such signal molecules are used as guideposts to find distal targets. Glial, and sometimes neuronal, midline structures represent intermediate targets when axons cross the midline to reach the contralateral hemisphere. The subcommissural organ (SCO), a specialized neuroepithelium located at the dorsal midline underneath the posterior commissure, releases SCO-spondin, a large glycoprotein belonging to the thrombospondin superfamily that shares molecular domains with axonal pathfinding molecules. Several evidences suggest that the SCO could be involved in the development of the PC. First, both structures display a close spatiotemporal relationship. Second, certain mutants lacking an SCO present an abnormal PC. Third, some axonal guidance molecules are expressed by SCO cells. Finally, SCO cells, the Reissner's fiber (the aggregated form of SCO-spondin), or synthetic peptides from SCO-spondin affect the neurite outgrowth or neuronal aggregation in vitro. PMID:22559938
Posterior condyle surface damage on retrieved femoral knee components.
Burnell, Colin D C; Brandt, Jan-M; Petrak, Martin J; Bourne, Robert B
2011-12-01
Twenty-two retrieved femoral knee components were identified with posterior condyle surface damage on average at 99° flexion (range, 43°-135° flexion). Titanium alloy material transfer and abrasive surface damage were evident on cobalt-chromium alloy femoral components that were in contact with titanium alloy tibial trays. Surface damage on the retrieved Oxinium femoral components (Smith and Nephew, Inc, Memphis, Tenn) that were in contact with titanium alloy tibial trays showed gouging, associated with the removal and cracking of the oxide and exposure of the zirconium-niobium alloy substrate. Cobalt-chromium alloy femoral components that were in contact with cobalt-chromium alloy tibial trays showed abrasive wear. Contact between the femoral component and tibial tray should be avoided to prevent surface damage to the femoral condyles, which could potentially accelerate polyethylene wear in vivo. PMID:21570806
Rosette-forming glioneuronal tumors of the posterior fossa.
Shah, Manish N; Leonard, Jeffrey R; Perry, Arie
2010-01-01
Rosette-forming glioneuronal tumor (RGNT) of the fourth ventricle is a rare, recently described WHO Grade I neoplasm. The authors report 6 examples of RGNT arising primarily from the cerebellar vermis. All the patients were female, and the mean age of presentation was 24.8 years. The original diagnoses included pilocytic astrocytoma, ependymoma, cerebellar dysembryoplastic neuroepithelial tumor (DNT), and oligodendroglioma. The cases showed classic pathological characteristics, although in 2 cases the lesions included DNT-like "floating neurons" involving Purkinje cells, a feature which has not been previously reported to the authors' knowledge. The clinical outcome was excellent with no recurrences after complete resection. These cases expand the known clinical and histological spectrum of this rare tumor type. Given the lack of fourth ventricle involvement in most of these cases, the authors suggest revising the name to RGNT of the posterior fossa. PMID:20043744
Posterior spinal artery aneurysm rupture after 'Ecstasy' abuse.
Johnson, Jeremiah; Patel, Shnehal; Saraf-Lavi, Efrat; Aziz-Sultan, Mohammad Ali; Yavagal, Dileep R
2015-07-01
Posterior spinal artery (PSA) aneurysms are a rare cause of subarachnoid hemorrhage (SAH). The commonly abused street drug 3,4-methylenedioxymethamphetamine (MDMA) or 'Ecstasy' has been linked to both systemic and neurological complications. A teenager presented with neck stiffness, headaches and nausea after ingesting 'Ecstasy'. A brain CT was negative for SAH but a CT angiogram suggested cerebral vasculitis. A lumbar puncture showed SAH but a cerebral angiogram was negative. After a spinal MR angiogram identified abnormalities on the dorsal surface of the cervical spinal cord, a spinal angiogram demonstrated a left PSA 2?mm fusiform aneurysm. The patient underwent surgery and the aneurysmal portion of the PSA was excised without postoperative neurological sequelae. 'Ecstasy' can lead to neurovascular inflammation, intracranial hemorrhage, SAH and potentially even de novo aneurysm formation and subsequent rupture. PSA aneurysms may be treated by endovascular proximal vessel occlusion or open surgical excision. PMID:25006043
Cervical Spinal Epidural Hematoma Following Cervical Posterior Laminoforaminotomy
Choi, Jeong Hoon; Lee, Sang-Ho
2013-01-01
A 65-year-old man who had lateral cervical disc herniation underwent cervical posterior laminoforaminotomy at C5-6 and C6-7 level right side. During the operation, there was no serious surgical bleeding event. After operation, he complained persistent right shoulder pain and neck pain. Repeated magnetic resonance image (MRI) showed diffuse cervical epidural hematoma (EDH) extending from C5 to T1 level right side and spinal cord compression at C5-6-7 level. He underwent exploration. There was active bleeding at muscular layer. Muscular active bleeding was controlled and intramuscular hematoma was removed. The patient's symptom was reduced after second operation. Symptomatic postoperative spinal EDH requiring reoperation is rare. Meticulous bleeding control is important before wound closure. In addition, if patient presents persistent or aggravated pain after operation, rapid evaluation using MRI and second look operation is needed as soon as possible. PMID:23560180
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 ?-ellipticity, has a biased maximum likelihood but an unbiased mean; and that the third eccentricity, or normalized polarization ?, 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.
Neuronal connections through the posterior commissure in the frog Rana esculenta.
Lázár, G; Pál, E
1999-01-01
The cobalt-labelling technique was used. After iontophoretic injections of cobaltic-lysine complex into the posterior commissure, fibres and neurons were bilaterally labelled in the posterior thalamic nucleus, three other pretectal nuclei, the optic tectum, the nucleus of the medial longitudinal fasciculus, and in the basal optic nucleus. Unilateral cobalt injections into the terminal areas of the posterior commissure in the mesencephalic tegmentum, labelled neurons in the above-mentioned nuclei ipsilaterally, and some cells contralaterally. The connections through the frog's posterior commissure are very similar to those in mammals. PMID:10536869
Posterior Tibial Tendon Dysfunction and Flatfoot: Analysis with Simulated Walking
Watanabe, Kota; Kitaoka, Harold B.; Fujii, Tadashi; Crevoisier, Xavier M.; Berglund, Lawrence J.; Zhao, Kristin D.; Kaufman, Kenton R.; An, Kai-Nan
2012-01-01
Many biomechanical studies investigated pathology of flatfoot and effects of operations on flatfoot. The majority of cadaveric studies are limited to the quasistatic response to static joint loads. This study examined the unconstrained joint motion of the foot and ankle during stance phase utilizing a dynamic foot-ankle simulator in simulated stage 2 posterior tibial tendon dysfunction (PTTD). Muscle forces were applied on the extrinsic tendons of the foot using six servo-pneumatic cylinders to simulate their action. Vertical and fore-aft shear forces were applied and tibial advancement was performed with the servomotors. Three-dimensional movements of multiple bones of the foot were monitored with a magnetic tracking system. Twenty-two fresh-frozen lower extremities were studied in the intact condition, then following sectioning peritalar constraints to create a flatfoot and unloading the posterior tibial muscle force. Kinematics in the intact condition were consistent with gait analysis data for normals. There were altered kinematics in the flatfoot condition, particularly in coronal and transverse planes. Calcaneal eversion relative to the tibia averaged 11.1±2.8° compared to 5.8±2.3° in the normal condition. Calcaneal-tibial external rotation was significantly increased in flatfeet from mean of 2.3±1.7° to 8.1±4.0°. There were also significant changes in metatarsal-tibial eversion and external rotation in the flatfoot condition. The simulated PTTD with flatfoot was consistent with previous data obtained in patients with PTTD. The use of a flatfoot model will enable more detailed study on the flatfoot condition and/or effect of surgical treatment. PMID:22939754
Posterior tibiotalar ligament: an anatomic study correlated with MRI.
Won, Hyung-Jin; Won, Hyung-Sun; Oh, Chang-Seok; Han, Seung-Ho; Chung, In-Hyuk; Suh, Jin-Suck; Lee, Woo-Chun
2014-07-01
This study was performed to clarify the morphologic characteristics of two layers of the posterior tibiotalar ligament (PTT) and two bands of the deep PTT (dPTT), and to correlate the dissection findings with MR images. Sixty-four ankles from 42 cadavers were examined. The origin and insertion sites of the superficial PTT (sPTT) and the two bands of the dPTT were identified, and their length, width, and thickness were measured. MRI was performed on four ankles before serial sectioning or dissection. The serial sections were taken at a thickness of 2 mm. The sPTT was observed in 50 out of 60 dissected specimens (83.3%), taken from 64 ankles of 42 cadavers. The dPTT was observed in all specimens. The sPTT, superficial band of the dPTT (sdPTT), and deep band of the dPTT (ddPTT) arose from the inferior surface of the medial malleolus. The sPTT attached to the posterior process of the talus, and the sdPTT and ddPTT attached to the depression below the articular facet for the medial malleolus. The sPTT and two bands of the dPTT could be distinguished on coronal MR images, where the sPTT appeared as a thin string superficial to the two bands of the dPTT, which were separated as two thick, low-density strings. In the coronal plane of frozen sections, the outermost sPTT appeared as a thin, white bundle attached to the sdPTT. The PTT is composed of superficial and deep layers, and the dPTT is composed of superficial and deep bands. PMID:24038173
Probability matching and strategy availability.
Koehler, Derek J; James, Greta
2010-09-01
Findings from two experiments indicate that probability matching in sequential choice arises from an asymmetry in strategy availability: The matching strategy comes readily to mind, whereas a superior alternative strategy, maximizing, does not. First, compared with the minority who spontaneously engage in maximizing, the majority of participants endorse maximizing as superior to matching in a direct comparison when both strategies are described. Second, when the maximizing strategy is brought to their attention, more participants subsequently engage in maximizing. Third, matchers are more likely than maximizers to base decisions in other tasks on their initial intuitions, suggesting that they are more inclined to use a choice strategy that comes to mind quickly. These results indicate that a substantial subset of probability matchers are victims of "underthinking" rather than "overthinking": They fail to engage in sufficient deliberation to generate a superior alternative to the matching strategy that comes so readily to mind. PMID:20852231
Welcome to Probability by Surprise
NSDL National Science Digital Library
Several applets that demonstrate concepts of probability using graphics and animations are presented on this Web site. Rather than getting into the details of specific theories, the applets avoid heavy number crunching and instead expose the user to example situations that generalize probabilistic concepts. This can be beneficial by letting the user see the effects of certain principles and infer how they will hold in other situations. One of the most basic applets is the Say Red Applet, which demonstrates how repeatedly choosing one of two equally likely outcomes will result in breaking even on the number of right and wrong guesses. Other applets, such as the one dealing with conditional probabilities, are more elaborate. The only criticism of this site is its lack of instructions for using the applets; however, most are quite self explanatory.
JSTOR: Annals of Applied Probability
NSDL National Science Digital Library
1999-01-01
This journal from The Institute of Mathematical Statistics is now available online. Annals of Applied Probability, Vols. 1-3 (1991-1993)is fully accessible to the hundreds of academic institutions participating in JSTOR. The journal may be searched by keyword, full-text, title, author, and abstract, or browsed by date of publication. A list of JSTOR participants is provided at the JSTOR site.
Probability and combinatorics Michael Anshelevich
Anshelevich, Michael
Probability and combinatorics Michael Anshelevich Texas A&M University May 1, 2012 Michael and combinatorics #12;Fourier transform. Definition. Fourier transform FX() = eix dµX(x) = E[eiX ] Lemma. If X, Y independent, FX+Y () = FX()FY (). Proof. E[ei(X+Y ) ] = E[eiX eiY ] = E[eiX ]E[eiY ] Michael Anshelevich
Data Analysis: Probability and Technology
NSDL National Science Digital Library
2012-01-01
This series of three computer based lesson plans requires students to create specific virtual spinners and complete numerous trials in order to determine the difference between theoretical and experimental probability. By completing a large number of trials students discover the law of large numbers. In the third activity students create their own spinner and determine the likelihood of each event. The lesson plan includes a link to the Virtual Spinner which is cataloged separately. All worksheets are included for these activities.
Advances in Regionalising Flood Probabilities
Ralf Merz
\\u000a Flood regionalisation methods are used to estimate floods of a given excedance probability, such as the 100-year flood, in\\u000a ungauged catchments, i.e. catchments, where no local streamflow data are available. They can also be used to improve flood\\u000a estimates from local data in gauged catchments. The main idea of flood regionalisation methods is to transfer flood information\\u000a from hydrologically similar
Accurate natural convection modelling for magnetic components
Vencislav Valchev; Alex Van Den Bossche
2003-01-01
An accurate presentation of convection heat transfer in magnetic components is proposed for isothermal surface approach. The presented improved modelling of convection heat transfer includes also the effects of the orientation of the component and the influence of the ambient temperature. The proposed modelling is verified by comparison with experimental data obtained for an experimental box shape. The carried out
Can Appraisers Rate Work Performance Accurately?
ERIC Educational Resources Information Center
Hedge, Jerry W.; Laue, Frances J.
The ability of individuals to make accurate judgments about others is examined and literature on this subject is reviewed. A wide variety of situational factors affects the appraisal of performance. It is generally accepted that the purpose of the appraisal influences the accuracy of the appraiser. The instrumentation, or tools, available to the…
Accurate and Efficient Algorithms for Floating
Koev, Plamen
i i Accurate and Efficient Algorithms for Floating Point Computation J. Demmel and P. Koev 1 expressions containing floating point numbers, and for computing matrix factorizations (like LU, the singular is challenging because our accuracy demand is much stricter than usual. The classes of floating point expressions
Accurate pointing of tungsten welding electrodes
NASA Technical Reports Server (NTRS)
Ziegelmeier, P.
1971-01-01
Thoriated-tungsten is pointed accurately and quickly by using sodium nitrite. Point produced is smooth and no effort is necessary to hold the tungsten rod concentric. The chemically produced point can be used several times longer than ground points. This method reduces time and cost of preparing tungsten electrodes.