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 ...
CONFIDENCE MEASURES FROM LOCAL POSTERIOR PROBABILITY ESTIMATES
Edinburgh, University of
CONFIDENCE MEASURES FROM LOCAL POSTERIOR PROBABILITY ESTIMATES Gethin Williams and Steve Renals.shef.ac.uk 1 #12;Abstract In this paper we introduce a set of related confidence measures for large vocabulary by an acceptor HMM acoustic model. In addition to their computational efficiency, these confidence measures
CONFIDENCE MEASURES FROM LOCAL POSTERIOR PROBABILITY ESTIMATES
Edinburgh, University of
CONFIDENCE MEASURES FROM LOCAL POSTERIOR PROBABILITY ESTIMATES Gethin Williams and Steve Renals.williams,s.renalsg@dcs.shef.ac.uk 1 #12; Abstract In this paper we introduce a set of related confidence measures for large vocabulary by an acceptor HMM acoustic model. In addition to their computational efficiency, these confidence measures
GNSS integer ambiguity validation based on posterior probability
NASA Astrophysics Data System (ADS)
Wu, Zemin; Bian, Shaofeng
2015-06-01
GNSS integer ambiguity validation is considered to be a challenge task for decades. Several kinds of validation tests are developed and widely used in these years, but theoretical basis is their weakness. Ambiguity validation theoretically is an issue of hypothesis test. In the frame of Bayesian hypothesis testing, posterior probability is the canonical standard that statistical decision should be based on. In this contribution, (i) we derive the posterior probability of the fixed ambiguity based on the Bayesian principle and modify it for practice ambiguity validation. (ii) The optimal property of the posterior probability test is proved based on an extended Neyman-Pearson lemma. Since validation failure rate is the issue users most concerned about, (iii) we derive the failure rate upper bound of the posterior probability test, so the user can use the posterior probability test either in the fixed posterior probability or in the fixed failure rate way. Simulated as well as real observed data are used for experimental validations. The results show that (i) the posterior probability test is the most effective within the R-ratio test, difference test, ellipsoidal integer aperture test and posterior probability test, (ii) the posterior probability test is computational efficient and (iii) the failure rate estimation for posterior probability test is useful.
GNSS integer ambiguity validation based on posterior probability
NASA Astrophysics Data System (ADS)
Wu, Zemin; Bian, Shaofeng
2015-10-01
GNSS integer ambiguity validation is considered to be a challenge task for decades. Several kinds of validation tests are developed and widely used in these years, but theoretical basis is their weakness. Ambiguity validation theoretically is an issue of hypothesis test. In the frame of Bayesian hypothesis testing, posterior probability is the canonical standard that statistical decision should be based on. In this contribution, (i) we derive the posterior probability of the fixed ambiguity based on the Bayesian principle and modify it for practice ambiguity validation. (ii) The optimal property of the posterior probability test is proved based on an extended Neyman-Pearson lemma. Since validation failure rate is the issue users most concerned about, (iii) we derive the failure rate upper bound of the posterior probability test, so the user can use the posterior probability test either in the fixed posterior probability or in the fixed failure rate way. Simulated as well as real observed data are used for experimental validations. The results show that (i) the posterior probability test is the most effective within the R-ratio test, difference test, ellipsoidal integer aperture test and posterior probability test, (ii) the posterior probability test is computational efficient and (iii) the failure rate estimation for posterior probability test is useful.
LARGE VOCABULARY DECODING AND CONFIDENCE ESTIMATION USING WORD POSTERIOR PROBABILITIES
Cambridge, University of
with the same word but corresponding to different segmentations and contexts. The word posterior estimationLARGE VOCABULARY DECODING AND CONFIDENCE ESTIMATION USING WORD POSTERIOR PROBABILITIES G. Evermann Email: {ge204,pcw}@eng.cam.ac.uk ABSTRACT This paper investigates the estimation of word posterior
Estimating the Class Posterior Probabilities in Biological Sequence Segmentation
Guermeur, Yann
Estimating the Class Posterior Probabilities in Biological Sequence Segmentation R´emi Bonidal segmentation problems on biological sequences, we advocate the use of a hybrid architecture combining by classifiers estimating the class posterior probabilities. The outputs of this cascade of classifiers, named
INDICATOR VARIABLE DEPENDENT OUTPUT PROBABILITY MODELLING VIA CONTINUOUS POSTERIOR FUNCTIONS
Young, Steve
INDICATOR VARIABLE DEPENDENT OUTPUT PROBABILITY MODELLING VIA CONTINUOUS POSTERIOR FUNCTIONS A. The posteriors are modelled by softmax functions with polynomial exponents and an efficient method is developed to model exclusively segments of phones. This ig- nores the fact that there are many other hidden states
Anisotropic Regularization of Posterior Probability Maps Using Vector Space
. Ruiz-Alzola1,2 1 Centro de Tecnolog´ia M´edica Universidad de Las Palmas de Gran Canaria and Hospital, the authors normalize the addition of posterior probabilities after each discrete iteration, assuming
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
Accurate Approximations for Posterior Moments and Marginal Densities
Luke Tierney; Joseph B. Kadane
1986-01-01
This article describes approximations to the posterior means and variances of positive functions of a real or vector-valued parameter, and to the marginal posterior densities of arbitrary (i.e., not necessarily positive) parameters. These approximations can also be used to compute approximate predictive densities. To apply the proposed method, one only needs to be able to maximize slightly modified likelihood functions
Efficient Posterior Probability Mapping Using Savage-Dickey Ratios
Penny, William D.; Ridgway, Gerard R.
2013-01-01
Statistical Parametric Mapping (SPM) is the dominant paradigm for mass-univariate analysis of neuroimaging data. More recently, a Bayesian approach termed Posterior Probability Mapping (PPM) has been proposed as an alternative. PPM offers two advantages: (i) inferences can be made about effect size thus lending a precise physiological meaning to activated regions, (ii) regions can be declared inactive. This latter facility is most parsimoniously provided by PPMs based on Bayesian model comparisons. To date these comparisons have been implemented by an Independent Model Optimization (IMO) procedure which separately fits null and alternative models. This paper proposes a more computationally efficient procedure based on Savage-Dickey approximations to the Bayes factor, and Taylor-series approximations to the voxel-wise posterior covariance matrices. Simulations show the accuracy of this Savage-Dickey-Taylor (SDT) method to be comparable to that of IMO. Results on fMRI data show excellent agreement between SDT and IMO for second-level models, and reasonable agreement for first-level models. This Savage-Dickey test is a Bayesian analogue of the classical SPM-F and allows users to implement model comparison in a truly interactive manner. PMID:23533640
A Posterior Probability-Based System Hybridisation and Combination for Spoken Term Detection
Edinburgh, University of
the event that K appears in the speech segment from t1 to t2. A commonly used posterior probabilityA Posterior Probability-Based System Hybridisation and Combination for Spoken Term Detection Javier perfor- mance, we have presented a direct posterior-based confidence measure generated from a neural
On Using Entropy Information to Improve Posterior Probability-based Confidence Measures
Wang, Hsin-Min
enhances the discriminability of confidence measures by applying entropy information to the posteriorOn Using Entropy Information to Improve Posterior Probability-based Confidence Measures Tzan. In this paper, we propose a novel approach that reduces the confidence error rate of traditional posterior
Basu, Sanjib
are compared in point null hypothesis, precise hypothesis and one sided hypothesis tests. It is found match in point null hypothesis testing. They, however, do not match in one sided testing. Key words hypothesis testing. The performances of the posterior density ratio and the posterior probability of H 0
A model for equine breed identification using microsatellites and posterior probability testing
Chastain, Pepper Alise
1996-01-01
allele distributions observed in Arabians and Thoroughbreds. The model utilized a posterior probability algorithm across a multi-locus genotype to generate the relative likelihood that an individual was either pure Arabian (ARAB), a pure Thoroughbred...
Inference of posterior inclusion probability of QTLs in Bayesian shrinkage analysis.
Yang, Deguang; Han, Shanshan; Jiang, Dan; Yang, Runqing; Fang, Ming
2015-01-01
Bayesian shrinkage analysis estimates all QTLs effects simultaneously, which shrinks the effect of "insignificant" QTLs close to zero so that it does not need special model selection. Bayesian shrinkage estimation usually has an excellent performance on multiple QTLs mapping, but it could not give a probabilistic explanation of how often a QTLs is included in the model, also called posterior inclusion probability, which is important to assess the importance of a QTL. In this research, two methods, FitMix and SimMix, are proposed to approximate the posterior probabilities. Under the assumption of mixture distribution of the estimated QTL effect, FitMix and SimMix mathematically and intuitively fit mixture distribution, respectively. The simulation results showed that both methods gave very reasonable estimates for posterior probabilities. We also applied the two methods to map QTLs for the North American Barley Genome Mapping Project data. PMID:25857576
Silverman, Bernard
Posterior probability intervals for wavelet thresholding Stuart Barber, Guy P. Nason, and Bernard W), Abramovich and Sapatinas (1999), and Vidakovic (1998). Address for correspondence: Stuart Barber, Department of Mathematics, University Walk, University of Bristol, Bristol, BS8 1TW, UK. Email: Stuart.Barber
Nason, Guy
Posterior probability intervals for wavelet thresholding Stuart Barber, Guy P. Nason, and Bernard W: Stuart Barber, Department of Mathematics, University Walk, University of Bristol, Bristol, BS8 1TW, UK. Email: Stuart.Barber@bristol.ac.uk 1 #12; A recent proposal for estimation of inhomogeneous g is wavelet
Barber, Stuart
Posterior probability intervals for wavelet thresholding Stuart Barber, Guy P. Nason, and Bernard W for correspondence: Stuart Barber, Department of Mathematics, University Walk, University of Bristol, Bristol, BS8 1TW, UK. Email: Stuart.Barber@bristol.ac.uk 1 #12;the same prior as the BayesThresh method
Posterior Probability Estimation Techniques Embedded in a Bayes Filter for Vibration-based
Zell, Andreas
Posterior Probability Estimation Techniques Embedded in a Bayes Filter for Vibration-based Terrain Classification Philippe Komma and Andreas Zell Abstract Vibration signals acquired during robot traversal provide] or ladar sensors [15, 10] can be employed. Recently, several researchers considered vehicle vibrations
Accurate photometric redshift probability density estimation - method comparison and application
NASA Astrophysics Data System (ADS)
Rau, Markus Michael; Seitz, Stella; Brimioulle, Fabrice; Frank, Eibe; Friedrich, Oliver; Gruen, Daniel; Hoyle, Ben
2015-10-01
We introduce an ordinal classification algorithm for photometric redshift estimation, which significantly improves the reconstruction of photometric redshift probability density functions (PDFs) for individual galaxies and galaxy samples. As a use case we apply our method to CFHTLS galaxies. The ordinal classification algorithm treats distinct redshift bins as ordered values, which improves the quality of photometric redshift PDFs, compared with non-ordinal classification architectures. We also propose a new single value point estimate of the galaxy redshift, which can be used to estimate the full redshift PDF of a galaxy sample. This method is competitive in terms of accuracy with contemporary algorithms, which stack the full redshift PDFs of all galaxies in the sample, but requires orders of magnitude less storage space. The methods described in this paper greatly improve the log-likelihood of individual object redshift PDFs, when compared with a popular neural network code (ANNZ). In our use case, this improvement reaches 50 per cent for high-redshift objects (z ? 0.75). We show that using these more accurate photometric redshift PDFs will lead to a reduction in the systematic biases by up to a factor of 4, when compared with less accurate PDFs obtained from commonly used methods. The cosmological analyses we examine and find improvement upon are the following: gravitational lensing cluster mass estimates, modelling of angular correlation functions and modelling of cosmic shear correlation functions.
Land-use/land-cover change detection using change-vector analysis in posterior probability space
NASA Astrophysics Data System (ADS)
Chen, Xuehong; Chen, Jin; Shen, Miaogen; Yang, Wei
2008-10-01
Land use/land cover change is an important field in global environmental change research. Remote sensing is a valuable data source from which land use/land cover change information can be extracted efficiently. A number of techniques for accomplishing change detection using satellite imagery have been formulated, applied, and evaluated, which can be generally grouped into two types. (1) Those based on spectral classification of the input data such as post-classification comparison and direct two-date classification; and (2) those based on radiometric change between different acquisition dates. The shortage of type 1 is cumulative error in image classification of an individual date. However, radiometric change approaches has a strict requirement for reliable image radiometry. In light of the above mentioned drawbacks of those two types of change detection methods, this paper presents a new method named change vector analysis in posterior probability space (CVAPS). Change-vector analysis (CVA) is one of the most successful radiometric change-based approaches. CVAPS approach incorporates post-classification comparison method and CVA approach, which is expected to inherit the advantages of two traditional methods and avoid their defects at the same time. CVAPS includes the following four steps. (1) Images in different periods are classified by certain classifier which can provide posterior probability output. Then, the posterior probability can be treated as a vector, the dimension of which is equal to the number of classes. (2) A procedure similar with CVA is employed. Compared with traditional CVA, new method analyzes the change vector in posterior probability space instead of spectral feature space. (3) A semiautomatic method, named Double-Window Flexible Pace Search (DFPS), is employed to determine the threshold of change magnitude. (4) Change category is discriminated by cosines of the change vectors. CVAPS approach was applied and validated by a case study of land use change detection in urban area of Shenzhen, China using multi-temporal TM data. Kappa coefficients of "change/no-change" detection and "from-to" types of change detection were employed for accuracy assessment. The experimental results show that CVAPS outperform than post-classification comparison method and can avoid cumulative error effectively. Besides, radiometric correction is not needed in this method compared with traditional CVA. Therefore, it is indicated that CVAPS is potentially useful in land-use/land-cover change detection.
Accurate photometric redshift probability density estimation - method comparison and application
Rau, Markus Michael; Brimioulle, Fabrice; Frank, Eibe; Friedrich, Oliver; Gruen, Daniel; Hoyle, Ben
2015-01-01
We introduce an ordinal classification algorithm for photometric redshift estimation, which vastly improves the reconstruction of photometric redshift probability density functions (PDFs) for individual galaxies and galaxy samples. As a use case we apply our method to CFHTLS galaxies. The ordinal classification algorithm treats distinct redshift bins as ordered values, which improves the quality of photometric redshift PDFs, compared with non-ordinal classification architectures. We also propose a new single value point estimate of the galaxy redshift, that can be used to estimate the full redshift PDF of a galaxy sample. This method is competitive in terms of accuracy with contemporary algorithms, which stack the full redshift PDFs of all galaxies in the sample, but requires orders of magnitudes less storage space. The methods described in this paper greatly improve the log-likelihood of individual object redshift PDFs, when compared with a popular Neural Network code (ANNz). In our use case, this improvemen...
NASA Astrophysics Data System (ADS)
Du, Zhanwei; Yang, Yongjian; Bai, Yuan; Wang, Lijun; Su, Le; Chen, Yong; Li, Xianchang; Zhou, Xiaodong; Jia, Jun; Shen, Aiguo; Hu, Jiming
2013-03-01
The existing methods for early and differential diagnosis of oral cancer are limited due to the unapparent early symptoms and the imperfect imaging examination methods. In this paper, the classification models of oral adenocarcinoma, carcinoma tissues and a control group with just four features are established by utilizing the hybrid Gaussian process (HGP) classification algorithm, with the introduction of the mechanisms of noise reduction and posterior probability. HGP shows much better performance in the experimental results. During the experimental process, oral tissues were divided into three groups, adenocarcinoma (n = 87), carcinoma (n = 100) and the control group (n = 134). The spectral data for these groups were collected. The prospective application of the proposed HGP classification method improved the diagnostic sensitivity to 56.35% and the specificity to about 70.00%, and resulted in a Matthews correlation coefficient (MCC) of 0.36. It is proved that the utilization of HGP in LRS detection analysis for the diagnosis of oral cancer gives accurate results. The prospect of application is also satisfactory.
Magee, Joseph W.
Accurate Atomic Transition Probabilities for Hydrogen, Helium, and Lithium W. L. Wiese and J. R transitions; atomic transition probabilities; f values; helium; hydrogen; line strengths; lithium; oscillator September 2009 We have carried out a comprehensive tabulation of the atomic transition probabilities
P-values, q-values and posterior probabilities for equivalence in genomics studies
Tuke, J; Solomon, P J
2012-01-01
Equivalence testing is of emerging importance in genomics studies but has hitherto been little studied in this content. In this paper, we define the notion of equivalence of gene expression and determine a `strength of evidence' measure for gene equivalence. It is common practice in genome-wide studies to rank genes according to observed gene-specific P-values or adjusted P-values, which are assumed to measure the strength of evidence against the null hypothesis of no differential gene expression. We show here, both empirically and formally, that the equivalence P-value does not satisfy the basic consistency requirements for a valid strength of evidence measure for equivalence. This means that the widely-used q-value (Storey, 2002) defined for each gene to be the minimum positive false discovery rate that would result in the inclusion of the corresponding P-value in the discovery set, cannot be translated to the equivalence testing framework. However, when represented as a posterior probability, we find that ...
Estimating the Posterior Probabilities Using the K-Nearest Neighbor Rule
Abu-Mostafa, Yaser S.
a classification) is required. This is usually the case when some confidence measure in the classification classification problem. For one thing, the optimal classifier (Bayes classifier) is based on classifying pattern classification problems an estimate of the posterior prob- abilities (rather than only
Effects of Branch Length Uncertainty on Bayesian Posterior Probabilities for Phylogenetic Hypotheses
Oregon, University of
probability--the probability that a tree or clade is true given the data, evolutionary model, and prior reliable measures of statistical confidence in evolutionary trees have long been sought. Bayesian of the evolutionary process, and prior probability distributions over trees and model parameters (Huelsenbeck et al
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
Magee, Joseph W.
Publisher's Note: "Accurate Atomic Transition Probabilities for Hydrogen, Helium, and Lithium" J doi:10.1063/1.3254213 Key words: allowed and forbidden transitions; atomic transition probabilities; f values; helium; hydrogen; line strengths; lithium; oscillator strengths. This article was originally
P-values, q-values and posterior probabilities for equivalence in genomics studies
Solomon, Patty
, and analyse data from a mouse stem cell microarray experiment which demonstrate the theory and methods probability; q-value; stem cell microarray experiment. 1 Introduction 1.1 Motivation for equivalence testing or treatment regimens provide comparable therapeutic effects within pre-defined clinical and statistical limits
Lindhiem, Oliver; Yu, Lan; Grasso, Damion J; Kolko, David J; Youngstrom, Eric A
2015-04-01
This study adapts the Posterior Probability of Diagnosis (PPOD) Index for use with screening data. The original PPOD Index, designed for use in the context of comprehensive diagnostic assessments, is overconfident when applied to screening data. To correct for this overconfidence, we describe a simple method for adjusting the PPOD Index to improve its calibration when used for screening. Specifically, we compare the adjusted PPOD Index to the original index and naïve Bayes probability estimates on two dimensions of accuracy, discrimination and calibration, using a clinical sample of children and adolescents (N = 321) whose caregivers completed the Vanderbilt Assessment Scale to screen for attention-deficit/hyperactivity disorder and who subsequently completed a comprehensive diagnostic assessment. Results indicated that the adjusted PPOD Index, original PPOD Index, and naïve Bayes probability estimates are comparable using traditional measures of accuracy (sensitivity, specificity, and area under the curve), but the adjusted PPOD Index showed superior calibration. We discuss the importance of calibration for screening and diagnostic support tools when applied to individual patients. PMID:25000935
van de Merwe, J P
1984-01-01
A program is presented for the Hewlett-Packard HP- 41C programmable hand-held calculator that calculates the posterior probability and relative risk of an event (e.g. a disease) on the basis of prior probability (prevalence) and sensitivity, specificity and result of the test. PMID:6370577
L. Allison; C. S. Wallace
1994-01-01
How to sample alignments from their posterior probability distribution given two strings is shown. This is extended to sampling alignments of more than two strings. The result is first applied to the estimation of the edges of a given evolutionary tree over several strings. Second, when used in conjunction with simulated annealing, it gives a stochastic search method for an
Fabien Heliot; Mohammad Ghavami; Mohammad Nakhai
2008-01-01
The log-normal probability distribution is com- monly used in wireless communications to model the shadowing and more recently the small scale fading for indoor ultra wide- band communications. In this paper, an accurate closed-form approximation of the average probability of error over a log- normal fading channel is derived for various constellation types and sizes. This expression can be used
Michalet, Xavier
in Fig. 2. A. Logarithm of the posterior probability (LPP) of bin number N (as defined in ref. 36 of the LPP on the optimal number of bin. A: the Log Posterior Probability (LPP) calculated on the original set, for M = 100 (gray box histogram) and the optimal bin number M = 37 (black histogram). In both
NSDL National Science Digital Library
Mr Clark
2012-10-31
Probability Guess the Probability Do you know the probability? Take an educated guess. Probability - Guess the next card What's the next card? Is it higher or lower? Probability knowledge will help. Fish Tank Probability Fish Tank Probability. Do you know what you'll catch next? Ball Probability Predict the probability red and blue balls will be chosen. ...
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.
Vladimir P. Dragalin; Alexander G. Tartakovsky; Venugopal V. Veeravalli
2000-01-01
For pt. I see ibid. vol.45, p.2448-61, 1999. We proved in pt.I that two specific constructions of multihypothesis sequential tests, which we refer to as multihypothesis sequential probability ratio tests (MSPRTs), are asymptotically optimal as the decision risks (or error probabilities) go to zero. The MSPRTs asymptotically minimize not only the expected sample size but also any positive moment of
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 ...
Crook, Paul A.
@inf.ed.ac.uk Oliver Lemon HCRC/ICCS, School of Informatics University of Edinburgh, UK olemon@gmail.com Abstract Decision Process (POMDP) Reinforcement Learning (RL) to dialogue management (Henderson and Lemon, 2008 in the probability estimate that it provides will have knock on effects in the updating of the belief state (which
Perret, D.
2010-01-01
Posterior knee pain is a common patient complaint. There are broad differential diagnoses of posterior knee pain ranging from common causes such as injury to the musculotendinous structures to less common causes such as osteochondroma. A precise understanding of knee anatomy, the physical examination, and of the differential diagnosis is needed to accurately evaluate and treat posterior knee pain. This article provides a review of the anatomy and important aspects of the history and physical examination when evaluating posterior knee pain. It concludes by discussing the causes and management of posterior knee pain. PMID:21063493
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
NASA Astrophysics Data System (ADS)
Atutov, S. N.; Plekhanov, A. I.
2015-01-01
We present the results of a systematic study of Knudsen's flow of Rb atoms in cylindrical capillary cells coated with a polydimethylsiloxane (PDMS) compound. The purpose of the investigation is to determine the characterization of the coating in terms of the sticking probability and sticking time of Rb on the two types of coating of high and medium viscosities. We report the measurement of the sticking probability of a Rb atom to the coating equal to 4.3 × 10-5, which corresponds to the number of bounces 2.3 × 104 at room temperature. These parameters are the same for the two kinds of PDMS used. We find that at room temperature, the respective sticking times for high-viscosity and medium-viscosity PDMS are 22 ± 3 ?s and 49 ± 6 ?s. These sticking times are about million times larger than the sticking time derived from the surface Rb atom adsorption energy and temperature of the coating. A tentative explanation of this surprising result is proposed based on the bulk diffusion of the atoms that collide with the surface and penetrate inside the coating. The results can be important in many resonance cell experiments, such as the efficient magnetooptical trapping of rare elements or radioactive isotopes and in experiments on the light-induced drift effect.
NSDL National Science Digital Library
2010-01-01
This lesson is designed to develop students' understanding of probability in real life situations. Students will also be introduced to running experiments, experimental probability, and theoretical probability. This lesson provides links to discussions and activities related to probability 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.
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
Posterior sampling with improved efficiency
Hanson, K.M.; Cunningham, G.S.
1998-12-01
The Markov Chain Monte Carlo (MCMC) technique provides a means to generate a random sequence of model realizations that sample the posterior probability distribution of a Bayesian analysis. That sequence may be used to make inferences about the model uncertainties that derive from measurement uncertainties. This paper presents an approach to improving the efficiency of the Metropolis approach to MCMC by incorporating an approximation to the covariance matrix of the posterior distribution. The covariance matrix is approximated using the update formula from the BFGS quasi-Newton optimization algorithm. Examples are given for uncorrelated and correlated multidimensional Gaussian posterior distributions.
Roweis, Sam
' Rule #15; Manipulating the basic de#12;nition of conditional probability gives one of the most be factored by selecting an ordering for the random variables and using the "chain rule": p(x; y; z factors: p(x; yjz) = p(xjz)p(yjz) 8z Be Careful! #15;Watch the context: e.g. Simpson's paradox #15; De#12
NASA Astrophysics Data System (ADS)
Yan, Wang-Ji; Katafygiotis, Lambros S.
2015-03-01
A two-stage fast Bayesian spectral density approach is proposed in this study to extract modal properties for the cases of separated modes and closely spaced modes. A novel technique for variable separation is developed so that the interaction between spectrum variables (i.e., frequency, damping ratio as well as the spectral density of modal excitation and prediction error) and spatial variables (i.e., mode shape components) can be decoupled completely for both cases. In a first stage, the spectrum variables can be identified through a so-called 'fast Bayesian spectral trace approach' (FBSTA) by employing the statistical properties of the sum of auto-spectral density, while the spatial variables can be estimated in a follow up second stage through 'fast Bayesian spectral density approach' (FBSDA) by using the statistical information of the entire spectral density matrix. This study also reveals the intrinsic relationship between FBSDA and 'fast Bayesian FFT approach' formulated recently when multiple sets of measurements are available. The newly developed two-stage Bayesian approach allows for a fast computation of the most probable values and covariance matrix of modal properties. The companion paper is devoted to assembling the local mode shape components corresponding to different setups to form the overall mode shapes using a Bayesian statistical framework and verifying the proposed algorithms through simulated and field testing data.
Posterior lip traction caused by intravitreal gas
Lincoff, H.; Kreissig, I.
1981-08-01
Traction on the posterior edge of a large tear may be an irreparable consequence of an intraocular gas tamponade used in the first instance to treat the tear. In two of three patients treated with octofluorocyclobutane (C4F8) and perfluoromethane (CF4), redetachment of a retinal tear occurred as a result of traction on the posterior edge of the tear when, prior to the operation, the posterior edge seemed to be free of any traction. With redetachment, a membrane became visible between the anterior and posterior lips of the tear. The membrane was probably posterior hyaloid augmented by cellular proliferation. The gas bubble, which had been intended to press the retina against the pigment epithelium, probably brought the detached posterior hyaloid into contact with the retina as well, and an adhesion between the hyaloid and retina formed.
V. Zumtobel; G. Heberer
1980-01-01
Summary The posterior approach provides excellent exposure of the midrectum when the operative procedure is a local one. The posterior rectotomy with coccygectomy (Kraske) causes impairment of wound healing and local pain. The transsphincteric approach (Mason) may carry the risk of incontinence. We, therefore, recommend the posterior rectotomy without coccygectomy and without dissection of the sphincter. Following posterior rectotomy a
Posterior fossa malformations.
Shekdar, Karuna
2011-06-01
Understanding embryologic development of the cerebellum and the 4th ventricle is essential for understanding posterior fossa malformations. Posterior fossa malformations can be conveniently classified into those that have a large posterior fossa and those with normal or small posterior fossa. Disorders associated with a large posterior fossa include classic Dandy-Walker malformation, Blake's pouch cyst, mega cisterna magna, and posterior fossa arachnoid cyst. Disorders associated with normal or small posterior fossa include Dandy-Walker variant, Joubert syndrome, tecto-cerebellar dysraphia, rhombencephalosynapsis, the neocerebellar hypoplasias, and cerebellar atrophy. Neuro-imaging features should enable the imager to provide the referring physician a logical approach to these complex posterior fossa malformations. PMID:21596278
A Posteriori Transit Probabilities
NASA Astrophysics Data System (ADS)
Stevens, Daniel J.; Gaudi, B. Scott
2013-08-01
Given the radial velocity (RV) detection of an unseen companion, it is often of interest to estimate the probability that the companion also transits the primary star. Typically, one assumes a uniform distribution for the cosine of the inclination angle i of the companion's orbit. This yields the familiar estimate for the prior transit probability of ˜R*, given the primary radius R* and orbital semimajor axis a, and assuming small companions and a circular orbit. However, the posterior transit probability depends not only on the prior probability distribution of i but also on the prior probability distribution of the companion mass Mc, given a measurement of the product of the two (the minimum mass Mcsin i) from an RV signal. In general, the posterior can be larger or smaller than the prior transit probability. We derive analytic expressions for the posterior transit probability assuming a power-law form for the distribution of true masses, d?/dMc?Mc?, for integer values -3?? ? 3. We show that for low transit probabilities, these probabilities reduce to a constant multiplicative factor f? of the corresponding prior transit probability, where f? in general depends on ? and an assumed upper limit on the true mass. The prior and posterior probabilities are equal for ?. The posterior transit probability is ˜1.5 times larger than the prior for ? = -3 and is ˜4/? times larger for ? = -2, but is less than the prior for ??0, and can be arbitrarily small for ? > 1. We also calculate the posterior transit probability in different mass regimes for two physically-motivated mass distributions of companions around Sun-like stars. We find that for Jupiter-mass planets, the posterior transit probability is roughly equal to the prior probability, whereas the posterior is likely higher for Super-Earths and Neptunes (10 M?-30 M?) and Super-Jupiters (MJup-10 MJup), owing to the predicted steep rise in the mass function toward smaller masses in these regimes. We therefore suggest that companions with minimum masses in these regimes might be better-than-expected targets for transit follow-up, and we identify promising targets from RV-detected planets in the literature. Finally, we consider the uncertainty in the transit probability arising from uncertainties in the input parameters, and the effect of ignoring the dependence of the transit probability on the true semimajor axis on i.
A Posterior Approach for Microphone Array Based Speech Recognition , Ivan Himawan1,2
Edinburgh, University of
for microphone array speech recogni- tion. Instead of enhancing speech signals, we enhance posterior phone enhances posterior probabilities, so might be called posterior beamform- ing, in the sense of channelA Posterior Approach for Microphone Array Based Speech Recognition Dong Wang1 , Ivan Himawan1
POSTERIOR-BASED CONFIDENCE MEASURES FOR SPOKEN TERM DETECTION , Javier Tejedor1,2
Edinburgh, University of
POSTERIOR-BASED CONFIDENCE MEASURES FOR SPOKEN TERM DETECTION Dong Wang1 , Javier Tejedor1,2 , Joe. The confidence measure expresses the posterior proba- bility of the search term appearing in the detection period- sired posterior probability. In this paper, we present a novel direct posterior-based confi- dence
Radiographic assessment of posterior malleolar ankle fractures.
Gonzalez, Olga; Fleming, Justin J; Meyr, Andrew J
2015-01-01
The anatomy of the posterior tibial malleolus plays an important role in the structure and function of the ankle mortise. With specific respect to ankle fractures, the presence, size, and displacement of posterior malleolar fractures (Volkmann's fracture) helps determine which will be amendable to operative fixation. The objective of the present study was to increase the body of knowledge with respect to the ability of foot and ankle reconstructive surgeons to assess posterior malleolar ankle fractures using plain film radiography. Three different variables were investigated on Sawbones(®) models: (1) differing size of posterior malleolar fractures (10%, 25%, and 50% of the tibial plafond), (2) differing displacement of posterior malleolar fractures (0 and 5 mm of proximal displacement), and (3) 2 different radiographic projections (standard lateral and externally rotated lateral projections). Accurate identification of the posterior malleolar fracture occurred on 86.67% (26 of 30) of standard lateral radiographs and 100% (30 of 30) of externally rotated lateral radiographs. Furthermore, the surgeons described the fracture with greater precision and had greater interclass correlation coefficient values with respect to measurement of sagittal plane displacement (0.977 versus 0.939) and percentage of involvement of the tibial plafond (0.972 versus 0.775) with an externally rotated lateral projection compared with a standard lateral projection. Our results provide evidence that an externally rotated lateral radiographic projection can provide surgeons with some additional information with respect to the presence, size, and displacement of posterior malleolar ankle fractures. PMID:25262838
Posterior instrumentation in scoliosis
J. K. Webb; R. G. Burwell; A. A. Cole; I. Lieberman
1995-01-01
The aims of posterior fusion and instrumentation in scoliosis are to achieve and maintain correction of the deformity and balance the spine in three planes, whilst keeping the fusion as short as possible and protecting the spinal cord. Harrington developed the first generation of posterior instrumentation, which considered only frontal plane correction. Since that time there has been an evolution
Maximum Entropy Based Normalization of Word Posteriors for Phonetic and LVCSR Lattice Search
Peng Yu; Duo Zhang; Frank Seide
2006-01-01
In many key word-spotting systems, the word posterior probability is an elementary quantity. In theory, the posterior of a keyword match denotes the probability of the match being correct. However, posteriors estimated on lattices, in particular phoneme lattices, are often off by orders of magnitude. This paper investigates the problem of providing \\
McIlwain, J C
1991-06-01
The posterior glottis is an area of the larynx previously referred to by the terms 'posterior commissure' and 'interarytenoid'; these are poorly defined and a new definition of this unique area of the larynx is provided. Within the text is a series of experiments performed on nearly 300 larynges. The posterior glottis was examined in relation to the following: the embryology, the epithelium, mathematical dimensions, gross anatomy, microanatomical structures, submucosal spaces and the spread of carcinoma related to this area. Various significant findings were made. There exists a pharyngoglottic duct which divides the embryonic larynx into anterior (membranous) and posterior (cartilaginous) parts. The epithelium of the posterior glottis in neonates and non-smokers is respiratory in nature and the notion of a laryngeal respiratory function is reinforced by a mathematical analysis of the cross sectional areas of the larynx during inspiration. The presence of a posterior cricoarytenoid ligament which stabilizes the arytenoid is confirmed. The spread of carcinoma to the posterior glottis from the different primary laryngeal and pyriform fossa sites shows differing modes of invasion but in particular a direct extension and connection with the subglottis. The most significant conclusion from these studies is that the posterior glottis is so intimately related to the subglottis that it must be considered as part of the subglottis. The acceptance of this fact, however, requires a new definition of the larynx from that given by the American Joint Committee on Cancer Staging and that of U.I.C.C. The posterior glottis considered as part of the subglottis requires a review of our present understanding of the structure and function of the larynx and in particular the spread of cancer posteriorly. PMID:1875468
Bounding the Probability of Error for High Precision Recognition
Massachusetts at Amherst, University of
Bounding the Probability of Error for High Precision Recognition Andrew Kae Department of Computer posterior probabilities, we bound the prob- ability that any given word is incorrect under very general such as posterior probabilities which are supposed to represent confidences, are often wrong even when posterior
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.
Kastner, Sabine
about the attended category attended unattended attended unattended attended unattended attended unattended OSC posterior IPS anterior IPS frontal categoryinformation Scene-evoked activation patterns in OSC were biased towards the target category in spatially attended and unattended
Philosophy of Science Association Probability Kinematics and Commutativity
Wagner, Carl
Philosophy of Science Association Probability Kinematics and Commutativity Author(s): Carl G. Introduction.The much remarked "non-commutativity" of probability kinematics (Domotor 1982, Skyrms 1986, van identical posterior probabilities, then sequential probability-kinematical revisions behave just
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 approaches are based...
Lhoste-Trouilloud, A.
2012-01-01
The tibialis posterior tendon is the largest and anteriormost tendon in the medial ankle. It produces plantar flexion and supination of the ankle and stabilizes the plantar vault. Sonographic assessment of this tendon is done with high-frequency, linear-array transducers; an optimal examination requires transverse retromalleolar, longitudinal retromalleolar, and distal longitudinal scans, as well as dynamic studies. Disorders of the posterior tibial tendon include chronic tendinopathy with progressive rupture, tenosynovitis, acute rupture, dislocation and instability, enthesopathies. The most common lesion is a progressive “chewing gum” lesion that develops in a setting of chronic tendinopathy; it is usually seen in overweight women over 50 years of age with valgus flat feet. Medial ankle pain must also be carefully investigated, and the presence of instability assessed with dynamic maneuvers (forced inversion, or dorsiflexion) of the foot. Sonography plays an important role in the investigation of disorders involving the posterior tibial tendon. PMID:23396570
... if they are not cancerous. There is limited space in the posterior fossa, and the tumor can easily press on delicate structures if it grows. Depending on the type and size of the tumor, radiation treatment may also be used after surgery.
Posterior Chamber Hemorrhage during Fluorescein Angiography
Vilela, Manuel A. P.
2015-01-01
This paper provides the first reported case of acute posterior chamber hemorrhage during fluorescein angiography (FA). This is a case review with serial color photographs of the anterior segment. A 76-year-old male was referred for angiographic control of age-related macular degeneration. He was pseudophakic OU, BCVA 20/40 OU. He had mild hypertension, but not diabetes. He had had two previous angiograms without adverse effects. Difficulty was experienced in obtaining the images owing to a progressive reduction in the transparency of the media. A dense hemorrhage in the posterior chamber of the right eye was found, involving the visual axis. Thorough biomicroscopy, gonioscopy, and ultrasonic biomicroscopy showed that part of one of the haptics of the right intraocular lens (IOL) was touching and tearing the posterior face of the iris, without any visible synechiae, iris, or angle neovascularization. Anterior segment FA and posterior ultrasonography were normal. No similar case has been described in the literature involving dense progressive bleeding located in the capsular bag and posterior chamber, without any detectable triggering ocular event other than mydriasis and fluorescein injection. Contact of the iris or sulcus with part of the intraocular lens, aggravated by the intense use of mydriatics during the FA procedure, probably caused bleeding to happen. PMID:26221554
Posterior reversible encephalopathy syndrome.
Staykov, Dimitre; Schwab, Stefan
2012-02-01
Posterior reversible encephalopathy syndrome (PRES) is characterized by headache, altered mental status, visual disturbances, and seizures. Radiological features typically include edema of the posterior cerebral regions, especially of the parietooccipital lobes. Atypical imaging features, such as involvement of anterior cerebral regions, deep white matter, and the brain stem are also frequently seen. Vasoconstriction is common in vascular imaging. Different conditions have been associated with PRES, but toxemia of pregnancy, solid organ or bone marrow transplantation, immunosuppressive treatment, cancer chemotherapy, autoimmune diseases, and hypertension are most commonly described. The pathophysiology of PRES is unclear and different hypotheses are being discussed. Posterior reversible encephalopathy syndrome is best managed by monitoring and treatment in the setting of a neurointensive care unit. The prognosis is usually benign with complete reversal of clinical symptoms within several days, when adequate treatment is immediately initiated. Treatment of severe hypertension, seizures, and withdrawal of causative agents represent the hallmarks of specific therapy in PRES. Delay in diagnosis and treatment may lead to permanent neurological sequelae. Therefore, awareness of PRES is of crucial importance for the intensivist. PMID:21257628
Posterior shape models Thomas Albrecht
Vetter, Thomas
Posterior shape model Image segmentation Trochlear dysplasia a b s t r a c t We present a method to computePosterior shape models Thomas Albrecht , Marcel Lüthi, Thomas Gerig, Thomas Vetter Department the conditional distribution of a statistical shape model given partial data. The result is a ``posterior shape
Novel thoracoscopic approach to difficult posterior mediastinal tumors.
Al-Mufarrej, Faisal; Margolis, Marc; Tempesta, Barbara; Strother, Eric; Gharagozloo, Farid
2010-12-01
Thoracoscopic resection is the preferred treatment of posterior mediastinal tumors. However, thoracotomy may be necessary if the tumors are large or adherent; if they are demonstrate invasion or intraspinal growth; or if they are located in the superoposterior mediastinum or posterior costodiaphragmatic angle. We describe a case of a large, adherent posterior costodiaphragmatic mediastinal mass that would have been otherwise difficult to resect thoracoscopically if it were not for the three-dimensional visualization, greater dexterity, and accurate dissection offered by the Da Vinci robot. PMID:21170634
Robotic posterior retroperitoneal adrenalectomy.
Okoh, Alexis Kofi; Yigitbas, Hakan; Berber, Eren
2015-09-01
Since its initial description by Mercan et al. laparoscopic posterior retroperitoneal (PR) adrenalectomy has served as an alternaltive to the transabdominal (TL) approach for the treatment of adrenal pathologies. Robotic adrenal surgery has been reported to improve surgeon ergonomics and facilitate dissection. In patients with bilateral adrenal masses, PR adrenalectomy may be the approach of choice. We herein describe the technique, discuss its limitations and present a critical review of the current literature. J. Surg. Oncol. 2015; 112:302-304. © 2015 Wiley Periodicals, Inc. PMID:26073649
Monteagudo, Manuel; Maceira, Ernesto
2015-03-01
The posterior tibial tendon (PTT) helps the triceps surae to work more efficiently during ambulation. Disorders of the PTT include tenosynovitis, acute rupture, degenerative tears, dislocation, instability, enthesopathies, and chronic tendinopathy with dysfunction and flat foot deformity. Open surgery of the PTT has been the conventional approach to deal with these disorders. However, tendoscopy has become a useful technique to diagnose and treat PTT disorders. This article focuses on PTT tendoscopy and tries to provide an understanding of the pathomechanics of the tendon, indications for surgery, surgical technique, advantages, complications, and limitations of this procedure. PMID:25726479
Crutch, Sebastian J; Lehmann, Manja; Schott, Jonathan M; Rabinovici, Gil D; Rossor, Martin N; Fox, Nick C
2013-01-01
Posterior cortical atrophy (PCA) is a neurodegenerative syndrome that is characterized by a progressive decline in visuospatial, visuoperceptual, literacy and praxic skills. The progressive neurodegeneration affecting parietal, occipital and occipito-temporal cortices which underlies PCA is attributable to Alzheimer's disease (AD) in the majority of patients. However, alternative underlying aetiologies including Dementia with Lewy Bodies (DLB), corticobasal degeneration (CBD) and prion disease have also been identified, and not all PCA patients have atrophy on clinical imaging. This heterogeneity has led to diagnostic and terminological inconsistencies, caused difficulty comparing studies from different centres, and limited the generalizability of clinical trials and investigations of factors driving phenotypic variability. Significant challenges remain in identifying the factors associated with both the selective vulnerability of posterior cortical regions and the young age of onset seen in PCA. Greater awareness of the syndrome and agreement over the correspondence between syndrome-and disease-level classifications are required in order to improve diagnostic accuracy, research study design and clinical management. PMID:22265212
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.
Generalizing Swendsen-Wang to Sampling Arbitrary Posterior Probabilities
Barbu, Adrian
for specific energy forms [17] and are not generally applicable. In this paper, we present a new inference, but they are limited to specific forms of energy functions and, thus, not generally applicable in visual inference. We-Chun Zhu Abstract--Many vision tasks can be formulated as graph partition problems that minimize energy
Efficient Posterior Probability Mapping Using Savage-Dickey Ratios
Penny, Will
be declared inactive. This latter facility is most parsimoniously provided by PPMs based on Bayesian model comparisons. To date these comparisons have been implemented by an Independent Model Optimization (IMO) procedure which separately fits null and alternative models. This paper proposes a more computationally
LARGE VOCABULARY DECODING AND CONFIDENCE ESTIMATION USING WORD POSTERIOR PROBABILITIES
Cambridge, University of
telephone speech corpora where improvements both in terms of word error rate and normalised cross entropy with the acoustic and language mode like- lihoods together with the start and end times of a particu- lar word hypothesis. Due to the context dependency of the acoustic and language models it is necessary to ensure
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
Ensemble Particle Filter with Posterior Gaussian By X. Xiong1
Ensemble Particle Filter with Posterior Gaussian Resampling By X. Xiong1 and I. M. Navon1 1School March 2005 ABSTRACT An ensemble particle filter(EnPF) was recently developed as a fully nonlinear fil- ter of Bayesian conditional probability estimation, along with the well known ensemble Kalman filter
Posterior cruciate ligament (PCL) injury
... injury is a partial or complete tearing or stretching of any part of the posterior cruciate ligament ( ... Taking nonsteroidal anti-inflammatory drugs (NSAIDs) for pain Limit physical activity until the swelling is down, motion ...
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…
Double bundle posterior cruciate ligament reconstruction: surgical technique and results.
Fanelli, Gregory C; Beck, John D; Edson, Craig J
2010-12-01
The keys to successful posterior cruciate ligament reconstruction are to identify and treat all pathology, use strong graft material, accurately place tunnels in anatomic insertion sites, minimize graft bending, use a mechanical graft tensioning device, use primary and back-up graft fixation, and use the appropriate postoperative rehabilitation program. Adherence to these technical principles results in successful single and double-bundle arthroscopic transtibial tunnel posterior cruciate ligament reconstruction based upon stress radiography, arthrometer, knee ligament rating scales, and patient satisfaction measurements. PMID:21079503
31. Probability 1 31. PROBABILITY
Masci, Frank
31. Probability 1 31. PROBABILITY Revised September 2007 by G. Cowan (RHUL). 31.1. General [1Â8] An abstract definition of probability can be given by considering a set S, called the sample space, and possible subsets A, B, . . ., the interpretation of which is left open. The probability P is a real
Shafer, Glenn R.; Shenoy, Prakash P.
1990-03-01
In this paper we give a simple account of local computation of marginal probabilities for when the joint probability distribution is given in factored form and the sets of variables involved in the factors form a hypertree. ...
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. ...
NSDL National Science Digital Library
Lacey, Michelle
This site, presented by the Department of Statistics at Yale University, gives an explanation, a definition and an example of probability models. Topics include components of probability models and the basic rules of probability. Overall, this is a great resource for any mathematics classroom studying statistics.
Unsuccessful outcomes after posterior urethroplasty.
Engel, Oliver; Fisch, Margit
2015-03-01
Posterior urethroplasty is the most common strategy for the treatment of post-traumatic urethral injuries. Especially in younger patients, post-traumatic injuries are a common reason for urethral strictures caused by road traffic accidents, with pelvic fracture or direct trauma to the perineum. In many cases early endoscopic realignment is the first attempt to restore the junction between proximal and distal urethra, but in some cases primary realignment is not possible or not enough to treat the urethral injury. In these cases suprapubic cystostomy alone and delayed repair by stricture excision and posterior urethroplasty is an alternative procedure to minimise the risk of stricture recurrence. PMID:26019980
Primary myelolipoma in posterior mediastinum.
Xiong, Yan; Wang, Yong; Lin, Yidan
2014-09-01
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
The neuropsychiatric profile of posterior cortical atrophy.
Isella, Valeria; Villa, Giulia; Mapelli, Cristina; Ferri, Francesca; Appollonio, Ildebrando Marco; Ferrarese, Carlo
2015-06-01
We analyzed scores obtained at the Neuropsychiatric Inventory (NPI) by 20 patients with posterior cortical atrophy (PCA) and contrasted it with 20 patients having Alzheimer disease (AD). Patients with hallucinations and delusions were not included due to the high probability of a diagnosis of Lewy body disease. Prevalence of behavioral and psychological symptoms (BPSD) was 95% in the PCA group, the most frequent being apathy and anxiety. Cluster analysis on NPI subscales highlighted a behavioral subsyndrome characterized by agitated temper and irritability. Depression, anxiety, and apathy did not cluster with any other BPSD nor with each other. The PCA group showed a significantly higher proportion of anxious patients and worse anxiety score than patients with AD. No correlation was found between NPI data and demographic, clinical, or neuropsychological features nor were there significant differences for the same variables between anxious and nonanxious cases with PCA. In agreement with anecdotal reports, anxiety seems particularly relevant in PCA. PMID:25330926
Lawler, J. E.; Guzman, A.; Wood, M. P.; Sneden, C.; Cowan, J. J. E-mail: adrianaguzman2014@u.northwestern.edu E-mail: chris@verdi.as.utexas.edu
2013-04-01
New atomic transition probability measurements for 948 lines of Ti I are reported. Branching fractions from Fourier transform spectra and from spectra recorded using a 3 m echelle spectrometer are combined with published radiative lifetimes from laser-induced fluorescence measurements to determine these transition probabilities. Generally good agreement is found in comparisons to the NIST Atomic Spectra Database. The new Ti I data are applied to re-determine the Ti abundance in the photospheres of the Sun and metal-poor star HD 84937 using many lines covering a range of wavelength and excitation potential to explore possible non-local thermal equilibrium effects. The variation of relative Ti/Fe abundance with metallicity in metal-poor stars observed in earlier studies is supported in this study.
Posterior Reversible Encephalopathy Syndrome in Children With Hematologic Malignancies.
Tavares, Márcio; Arantes, Mavilde; Chacim, Sérgio; Júnior, António Campos; Pinto, Armando; Mariz, José Mário; Sonin, Teresa; Pereira, Susana
2015-10-01
Since its original description 2 decades ago, posterior reversible encephalopathy syndrome has been reported in children with several predisposing conditions. Epidemiologic data of posterior reversible encephalopathy syndrome in children with hematologic malignancies is still scarce. Herein, we describe the clinical and radiologic features along with the outcome and follow-up of posterior reversible encephalopathy syndrome complicating the treatment of children with hematologic malignancies. Ten patients with a median age of 6.3 years were diagnosed with posterior reversible encephalopathy syndrome. Six of them were undergoing chemotherapy and the remaining 4 were at 37, 52, 78, and 857 days after allogenic hematopoietic stem cell transplant. The median follow-up was 27.6 months. Even though follow-up imaging showed complete resolution of abnormalities in those 10 children, 2 developed secondary epilepsy. Despite accurate diagnosis of posterior reversible encephalopathy syndrome and immediate intervention, neurologic sequelae may still develop. Thus, a close follow-up should be considered in all patients. PMID:25862738
Accuracy of Posterior Subtalar Joint Injection Without Fluoroscopy
Kirk, Kevin L.; Campbell, John T.; Guyton, Gregory P.
2008-01-01
Injection into the posterior subtalar joint has not been validated for accuracy using radiographic end points. We asked whether needle placement into a normal posterior subtalar joint could be performed accurately and selectively by experienced surgeons without fluoroscopic guidance. Three fellowship-trained orthopaedic foot and ankle surgeons each injected the posterior subtalar joint of 20 cadaveric specimens using an anterolateral approach. Fluoroscopic images were obtained by an independent investigator and blinded. A separate fellowship-trained foot and ankle surgeon interpreted the images. Of 60 injections, 58 were accurate and two were extraarticular based on interpretation by an independent foot and ankle surgeon. Extravasation into the ankle occurred in 14 samples and into the peroneal sheath in two samples. Experienced surgeons can place intraarticular injections into a radiographically normal posterior subtalar joint without fluoroscopy with a high degree of accuracy. However, extravasation into the ankle or peroneal tendon sheath occurred in an unpredictable fashion, suggesting selectivity of injection placement is relatively limited without the use of fluoroscopy. Fluoroscopy may not be necessary for injections used solely for therapeutic purposes. However, if the injection is intended for diagnostic purposes or to assist in surgical decision-making or if the joint is abnormal, we recommend fluoroscopy to ensure the subtalar joint is the only anatomic structure impacted by the injection. PMID:18404293
MRrelation: Posterior predictive mass distribution
NASA Astrophysics Data System (ADS)
Wolfgang, Angie; Rogers, Leslie A.; Ford, Eric B.
2015-04-01
MRrelation calculates the posterior predictive mass distribution for an individual planet. The probabilistic mass-radius relationship (M-R relation) is evaluated within a Bayesian framework, which both quantifies this intrinsic dispersion and the uncertainties on the M-R relation parameters.
Probability Distribution of Molecular Evolutionary Trees: A New Method of Phylogenetic Inference
Sullivan, Jack
Probability Distribution of Molecular Evolutionary Trees: A New Method of Phylogenetic Inference phylogenies are calculated and the phy- logeny with the highest posterior probability is chosen as the best- ability (MAP) tree. The posterior probability provides a natural measure of the reliability
Back to Normal! Gaussianizing posterior distributions for cosmological probes
NASA Astrophysics Data System (ADS)
Schuhmann, Robert L.; Joachimi, Benjamin; Peiris, Hiranya V.
2014-05-01
We present a method to map multivariate non-Gaussian posterior probability densities into Gaussian ones via nonlinear Box-Cox transformations, and generalizations thereof. This is analogous to the search for normal parameters in the CMB, but can in principle be applied to any probability density that is continuous and unimodal. The search for the optimally Gaussianizing transformation amongst the Box-Cox family is performed via a maximum likelihood formalism. We can judge the quality of the found transformation a posteriori: qualitatively via statistical tests of Gaussianity, and more illustratively by how well it reproduces the credible regions. The method permits an analytical reconstruction of the posterior from a sample, e.g. a Markov chain, and simplifies the subsequent joint analysis with other experiments. Furthermore, it permits the characterization of a non-Gaussian posterior in a compact and efficient way. The expression for the non-Gaussian posterior can be employed to find analytic formulae for the Bayesian evidence, and consequently be used for model comparison.
NSDL National Science Digital Library
T. L. Hui
2011-01-01
This online game, modeled after the classic game of "Plinko" from "The Price is Right", requires students to determine the probability of an event in percent form prior to "earning" their Plinko chips. The speed with which they answer each of the ten probability questions determines how many chips they earn. Students then use their knowledge of probability and chance to place their chips and try to get the highest score.
NSDL National Science Digital Library
Lacey, Michelle
This site, created by the Department of Statistics at Yale University gives an explanation, a definition and an example of conditional probability. Topics include the probabilities of intersections of events and Bayes' formula. Overall, this is a great resource for any mathematics classroom studying statistics.
Pediatric Posterior Sternoclavicular Joint Injuries.
Chaudhry, Sonia
2015-08-01
Posterior sternoclavicular joint injuries are increasingly diagnosed in children and young adults. Most of these injuries are the result of indirect mechanisms, typically lateral compression, with a posterior-to-anterior force applied to the shoulder during sports. Less frequently, these injuries are caused by direct impact on the medial clavicle, which can occur in rollover motor vehicle accidents, or may represent atraumatic instability. In patients younger than 25 years, physeal separation is more common than true dislocation. Theoretically, these patients have increased remodeling potential. Reduction is recommended to prevent and/or manage the compression of mediastinal structures, which can lead to life-threatening injury. Open surgical stabilization is the preferred treatment for acute and chronic retrosternal injuries. A thoracic or trauma surgeon should be available during stabilization in the rare event of potentially life-threatening hemorrhage after reduction. Outcomes have been largely successful, with pain-free, unrestricted range of motion and return to activity. PMID:26116848
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.
Nanotherapy for posterior eye diseases.
Kaur, Indu Pal; Kakkar, Shilpa
2014-11-10
It is assumed that more than 50% of the most enfeebling ocular diseases have their origin in the posterior segment. Furthermore, most of these diseases lead to partial or complete blindness, if left untreated. After cancer, blindness is the second most dreaded disease world over. However, treatment of posterior eye diseases is more challenging than the anterior segment ailments due to a series of anatomical barriers and physiological constraints confronted for delivery to this segment. In this regard, nanostructured drug delivery systems are proposed to defy ocular barriers, target retina, and act as permeation enhancers in addition to providing a controlled release. Since an important step towards developing effective treatment strategies is to understand the course or a route a drug molecule needs to follow to reach the target site, the first part of the present review discusses various pathways available for effective delivery to and clearance from the posterior eye. Promise held by nanocarrier systems, viz. liposomes, nanoparticles, and nanoemulsion, for effective delivery and selective targeting is also discussed with illustrative examples, tables, and flowcharts. However, the applicability of these nanocarrier systems as self-administration ocular drops is still an unrealized dream which is in itself a huge technological challenge. PMID:24862316
Spinal hemianesthesia: Unilateral and posterior
Imbelloni, Luiz Eduardo
2014-01-01
The injection of a non-isobaric local anesthetic should induce a unilateral spinal anesthesia in patients in a lateral decubitus position. The posterior spinal hemianesthesia only be obtained with hypobaric solutions injected in the jackknife position. The most important factors to be considered when performing a spinal hemianesthesia are: type and gauge of the needle, density of the local anesthetic relative to the CSF, position of the patient, speed of administration of the solution, time of stay in position, and dose/concentration/volume of the anesthetic solution. The distance between the spinal roots on the right-left sides and anterior-posterior is, approximately, 10-15 mm. This distance allows performing unilateral spinal anesthesia or posterior spinal anesthesia. The great advantage of obtaining spinal hemianesthesia is the reduction of cardiovascular changes. Likewise, both the dorsal and unilateral sensory block predominates in relation to the motor block. Because of the numerous advantages of producing spinal hemianesthesia, anesthesiologists should apply this technique more often. This review considers the factors which are relevant, plausible and proven to obtain spinal hemianesthesia. PMID:25886320
Transscleral drug delivery for posterior segment disease
Dayle H Geroski; Henry F Edelhauser
2001-01-01
Exciting new treatments are being developed for retinal degenerations and posterior segment eye disease. The successful treatment of these visually devastating diseases will likely require delivering effective doses of pharmacologic agents to the posterior segment, possibly in conjunction with surgical or genetic interventions. Currently, the treatment of diseases affecting the posterior segment is limited by the difficulty in delivering effective
Qualitative Probabilities for Image Interpretation Allan Jepson Richard Mannyz
Jepson, Allan D.
pruning based on the posterior probabilities of interpretations. However, due to the need for detailed of the posterior probabilityfor any interpretationas these res- olutions are made finer. We introduce this approach. For example, con- sider the image segments shown in Fig. 1a. A human ob- server might infer
Roweis, Sam
: represent a joint distribution P(X) = P(x 1 ;x 2 ; : : : ;xn ) eÆciently when there are many variables. #15 network: The joint probability is now: 1 X 2 X 3 X X4 X5 X 6 P(x 1 ;x 2 ;x 3 ;x 4 ;x 5 ;x 6 ) = P(x 1 )PLecture 2: Directed Graphical Models Sam Roweis January 8, 2003 Joint Probabilities #15; Goal
Markov chain Monte Carlo posterior sampling with the Hamiltonian method.
Hanson, Kenneth M.
2001-01-01
A major advantage of Bayesian data analysis is that provides a characterization of the uncertainty in the model parameters estimated from a given set of measurements in the form of a posterior probability distribution. When the analysis involves a complicated physical phenomenon, the posterior may not be available in analytic form, but only calculable by means of a simulation code. In such cases, the uncertainty in inferred model parameters requires characterization of a calculated functional. An appealing way to explore the posterior, and hence characterize the uncertainty, is to employ the Markov Chain Monte Carlo technique. The goal of MCMC is to generate a sequence random of parameter x samples from a target pdf (probability density function), {pi}(x). In Bayesian analysis, this sequence corresponds to a set of model realizations that follow the posterior distribution. There are two basic MCMC techniques. In Gibbs sampling, typically one parameter is drawn from the conditional pdf at a time, holding all others fixed. In the Metropolis algorithm, all the parameters can be varied at once. The parameter vector is perturbed from the current sequence point by adding a trial step drawn randomly from a symmetric pdf. The trial position is either accepted or rejected on the basis of the probability at the trial position relative to the current one. The Metropolis algorithm is often employed because of its simplicity. The aim of this work is to develop MCMC methods that are useful for large numbers of parameters, n, say hundreds or more. In this regime the Metropolis algorithm can be unsuitable, because its efficiency drops as 0.3/n. The efficiency is defined as the reciprocal of the number of steps in the sequence needed to effectively provide a statistically independent sample from {pi}.
Posterior consistency for Bayesian inverse problems through stability and regression results
NASA Astrophysics Data System (ADS)
Vollmer, Sebastian J.
2013-12-01
In the Bayesian approach, the a priori knowledge about the input of a mathematical model is described via a probability measure. The joint distribution of the unknown input and the data is then conditioned, using Bayes’ formula, giving rise to the posterior distribution on the unknown input. In this setting we prove posterior consistency for nonlinear inverse problems: a sequence of data is considered, with diminishing fluctuations around a single truth and it is then of interest to show that the resulting sequence of posterior measures arising from this sequence of data concentrates around the truth used to generate the data. Posterior consistency justifies the use of the Bayesian approach very much in the same way as error bounds and convergence results for regularization techniques do. As a guiding example, we consider the inverse problem of reconstructing the diffusion coefficient from noisy observations of the solution to an elliptic PDE in divergence form. This problem is approached by splitting the forward operator into the underlying continuum model and a simpler observation operator based on the output of the model. In general, these splittings allow us to conclude posterior consistency provided a deterministic stability result for the underlying inverse problem and a posterior consistency result for the Bayesian regression problem with the push-forward prior. Moreover, we prove posterior consistency for the Bayesian regression problem based on the regularity, the tail behaviour and the small ball probabilities of the prior.
Roweis, Sam
: represent a joint distribution P(X) = P(x 1 ;x 2 ; : : : ;xn ) compactly even when there are many variables; Probabilistic graphical models represent large joint distributions compactly using a set of \\local DAG #15; Consider this six node network: The joint probability is now: 1 X 2 X 3 X X4 X5 X 6 P(x 1 ;x
NSDL National Science Digital Library
2012-08-02
This interactive mathematics resource allows the user to explore the outcomes resulting from tossing a coin, rolling a die, and using a spinner to perform single and double event probabilities. The resource includes print activities, solutions, learning strategies, and a board game.
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.
Decoding Trajectories from Posterior Parietal Cortex Ensembles
Mulliken, Grant H.; Musallam, Sam; Andersen, Richard A.
2009-01-01
High-level cognitive signals in the posterior parietal cortex (PPC) have previously been used to decode the intended endpoint of a reach, providing the first evidence that PPC can be used for direct control of a neural prosthesis (Musallam et al., 2004). Here we expand on this work by showing that PPC neural activity can be harnessed to estimate not only the endpoint but also to continuously control the trajectory of an end effector. Specifically, we trained two monkeys to use a joystick to guide a cursor on a computer screen to peripheral target locations while maintaining central ocular fixation. We found that we could accurately reconstruct the trajectory of the cursor using a relatively small ensemble of simultaneously recorded PPC neurons. Using a goal-based Kalman filter that incorporates target information into the state-space, we showed that the decoded estimate of cursor position could be significantly improved. Finally, we tested whether we could decode trajectories during closed-loop brain control sessions, in which the real-time position of the cursor was determined solely by a monkey’s neural activity in PPC. The monkey learned to perform brain control trajectories at 80% success rate(for 8 targets) after just 4–5 sessions. This improvement in behavioral performance was accompanied by a corresponding enhancement in neural tuning properties (i.e., increased tuning depth and coverage of encoding parameter space) as well as an increase in off-line decoding performance of the PPC ensemble. PMID:19036985
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
NSDL National Science Digital Library
Vaillant, Noel
When the Scout Report last visited the Probability Tutorials in 1999, there were just twelve tutorials on this site. Since that time, the tutorials offered here have grown both in number (from twelve to twenty) and in their overall scope and breadth. The site was created and is still maintained by Noel Vaillant, who received his PhD from Imperial College, London. Currently, the site contains twenty detailed tutorials that cover almost every aspect of the field of probability. Some of the topics covered within these tutorials include metric topology and Gaussian measures. These tutorials are complemented by an introductory essay, a set of clear definitions of various terms, and a discussion board.
NSDL National Science Digital Library
Anderson-Cook, C.
This page, created by Virginia Tech's Department of Statistics, provides users with a myriad of different applets presenting different probability distributions. Some of these include: binomial, Poisson, negative binomial, geometric, t, chi-squared, gamma, Weibull, log-normal, beta and f distributions. Each applet is presented with an explanation of its use and also an example. Featuring eleven different applets, this is a useful and plentiful resource.
Heller, Barbara
probabilities in the standard normal table What is the area to the left of Z=1.51 in a standard normal curve? Z=1.51 Z=1.51 Area is 93.45% #12;Exercises Â· If scores are normally distributed with a mean of 30 beauty of the normal curve: No matter what and are, the area between - and + is about 68%; the area
The Non-Gaussian Sting in Posteriors arising from Marginal Detections
Bassett, Bruce A
2010-01-01
We show that in cases of marginal detections (~ 3 sigma), such as of Baryonic Acoustic Oscillations in cosmology, the full posterior probability for parameters is significantly non-Gaussian, due to the transition from the likelihood to the prior. This sting in the tail of the distribution radically alters confidence intervals on parameters and means that one cannot naively extrapolate 1-sigma error bars to 3-sigma and beyond as is typically done. We propose a simple formula which corrects for this effect in posterior probabilities arising from marginal detections.
A Review of Lesions of the Posterior Fourchette, Posterior Vestibule (Fossa Navicularis), and Hymen.
Heller, Debra S
2015-07-01
Lesions specific to the posterior fourchette, posterior vestibule (fossa navicularis), and hymen are reviewed. Knowledge of these regional lesions will be helpful if such a patient is encountered. PMID:25943866
Arthroscopic double-bundle posterior cruciate ligament reconstruction surgical technique.
Fanelli, Gregory C; Beck, John D; Edson, Craig J
2010-06-01
The keys to successful posterior cruciate ligament (PCL) reconstruction are to identify and treat all pathology, use strong graft material, accurately place tunnels in anatomic insertion sites, minimize graft bending, use a mechanical graft tensioning device, use primary and back-up graft fixation, and use the appropriate postoperative rehabilitation program. Adherence to these technical principles results in successful single-bundle and double-bundle arthroscopic transtibial tunnel PCL reconstruction based on stress radiography, arthrometer, knee ligament rating scales, and patient satisfaction measurements. PMID:21141685
Ordering genes: Controlling the decision-error probabilities
Rogatko, A.; Zacks, S. )
1993-05-01
Determination of the relative gene order on chromosomes is of critical importance in the construction of human gene maps. In this paper the authors develop a sequential algorithm for gene ordering. They start by comparing three sequential procedures to order three genes on the basis of Bayesian posterior probabilities, maximum-likelihood ratio, and minimal recombinant class. In the second part of the paper they extend sequential procedure based on the posterior probabilities to the general case of g genes. They present a theorem that states that the predicted average probability of committing a decision error, associated with a Bayesian sequential procedure that accepts the hypothesis of a gene-order configuration with posterior probability equal to or greater than [pi]*, is smaller than 1 - [pi]*. This theorem holds irrespective of the number of genes, the genetic model, and the source of genetic information. The theorem is an extension of a classical result of Wald, concerning the sum of the actual and the nominal error probabilities in the sequential probability ratio test of two hypotheses. A stepwise strategy for ordering a large number of genes, with control over the decision-error probabilities, is discussed. An asymptotic approximation is provided, which facilitates the calculations with existing computer software for gene mapping, of the posterior probabilities of an order and the error probabilities. They illustrate with some simulations that the stepwise ordering is an efficient procedure. 18 refs., 9 tabs.
Delp, Scott
Posterior Cruciate Ligament Removal Contributes to Abnormal Knee Motion during Posterior Stabilized Total Knee Arthroplasty Melinda J. Cromie,1,2 Robert A. Siston,1,2,3,4 Nicholas J. Giori,2,5 Scott L (20608) following posterior stabilized total knee arthroplasty. The underlying biomechanical causes
Gaussianisation for fast and accurate inference from cosmological data
Schuhmann, Robert L; Peiris, Hiranya V
2015-01-01
We present a method to transform multivariate unimodal non-Gaussian posterior probability densities into approximately Gaussian ones via non-linear mappings, such as Box--Cox transformations and generalisations thereof. This permits an analytical reconstruction of the posterior from a point sample, like a Markov chain, and simplifies the subsequent joint analysis with other experiments. This way, a multivariate posterior density can be reported efficiently, by compressing the information contained in MCMC samples. Further, the model evidence integral (i.e. the marginal likelihood) can be computed analytically. This method is analogous to the search for normal parameters in the cosmic microwave background, but is more general. The search for the optimally Gaussianising transformation is performed computationally through a maximum-likelihood formalism; its quality can be judged by how well the credible regions of the posterior are reproduced. We demonstrate that our method outperforms kernel density estimates i...
Posterior talus osteochondroma a rare location, treated by posterior ankle arthroscopy.
Kulkarni, Umesh; Kulkarni, Ameya
2015-09-01
The common cause of posterior ankle impingement syndrome is impingement of the Os trigonum or the posterior talar process. We report a case of a 46-year-old lady having osteochondroma of the posterior talar process, a rare occurrence at this site. This patient was treated with posterior ankle arthroscopic excision through the 2-portal posterior ankle arthroscopy technique in the prone position. 6 months post-operatively, her ankle pain disappeared and ankle range of movement improved significantly and there is no recurrence of the tumour. PMID:26235872
Andreas Blass; Yuri Gurevich
2015-02-02
This article was written for the Logic in Computer Science column in the February 2015 issue of the Bulletin of the European Association for Theoretical Computer Science. The intended audience is general computer science audience. The uncertainty principle asserts a limit to the precision with which position x and momentum p of a particle can be known simultaneously. You may know the probability distributions of x and p individually but the joint distribution makes no physical sense. Yet Wigner exhibited such a joint distribution f(x,p). There was, however, a little trouble with it: some of its values were negative. Nevertheless Wigner's discovery attracted attention and found applications. There are other joint distribution, all with negative values, which produce the correct marginal distributions of x and p. But only Wigner's distribution produces the correct marginal distributions for all linear combinations of position and momentum. We offer a simple proof of the uniqueness and discuss related issues.
Adaptive approximation of higher order posterior statistics
Lee, Wonjung
2014-02-01
Filtering is an approach for incorporating observed data into time-evolving systems. Instead of a family of Dirac delta masses that is widely used in Monte Carlo methods, we here use the Wiener chaos expansion for the parametrization of the conditioned probability distribution to solve the nonlinear filtering problem. The Wiener chaos expansion is not the best method for uncertainty propagation without observations. Nevertheless, the projection of the system variables in a fixed polynomial basis spanning the probability space might be a competitive representation in the presence of relatively frequent observations because the Wiener chaos approach not only leads to an accurate and efficient prediction for short time uncertainty quantification, but it also allows to apply several data assimilation methods that can be used to yield a better approximate filtering solution. The aim of the present paper is to investigate this hypothesis. We answer in the affirmative for the (stochastic) Lorenz-63 system based on numerical simulations in which the uncertainty quantification method and the data assimilation method are adaptively selected by whether the dynamics is driven by Brownian motion and the near-Gaussianity of the measure to be updated, respectively.
Meibomian Gland Dysfunction and Treatment (Posterior Blepharitis)
... Meibomian Gland Dysfunction and Treatment What are Meibomian (Oil) Glands? Meibomian glands are glands that are arranged ... lashes. The force of an eyelid blink causes oil to be excreted onto the posterior lid margin. ...
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
Multinomial mixture model with heterogeneous classification probabilities
Holland, M.D.; Gray, B.R.
2011-01-01
Royle and Link (Ecology 86(9):2505-2512, 2005) proposed an analytical method that allowed estimation of multinomial distribution parameters and classification probabilities from categorical data measured with error. While useful, we demonstrate algebraically and by simulations that this method yields biased multinomial parameter estimates when the probabilities of correct category classifications vary among sampling units. We address this shortcoming by treating these probabilities as logit-normal random variables within a Bayesian framework. We use Markov chain Monte Carlo to compute Bayes estimates from a simulated sample from the posterior distribution. Based on simulations, this elaborated Royle-Link model yields nearly unbiased estimates of multinomial and correct classification probability estimates when classification probabilities are allowed to vary according to the normal distribution on the logit scale or according to the Beta distribution. The method is illustrated using categorical submersed aquatic vegetation data. ?? 2010 Springer Science+Business Media, LLC.
Dechter, Rina
2009-01-01
Boosting Scheme for Bounding Posterior Beliefs1 Bozhena Bidyuk bbidyuk@google.com 19540 Jamboree Rd Irvine presents an any-time scheme for computing lower and upper bounds on the posterior marginals in Bayesian the probability of evidence, enhance its performance in an anytime manner, and transform it effectively
Katsuki, Fumi; Saito, Mizuki; Constantinidis, Christos
2014-01-01
The dorsolateral prefrontal and the posterior parietal cortex have both been implicated in the guidance of visual attention. Traditionally, posterior parietal cortex has been thought to guide visual bottom-up attention, whereas prefrontal cortex to bias attention through top-down information. More recent studies suggest a parallel time course of activation of the two areas in bottom-up attention tasks, suggesting a common involvement, though these results do not necessarily imply identical roles, either. To address the specific roles of the two areas, we examined the influence of neuronal activity recorded from the prefrontal and parietal cortex of monkeys as they performed attention tasks based on choice probability and correlation between reaction time and neuronal activity. The results revealed that posterior parietal but not dorsolateral prefrontal activity correlated with behavioral choice during the fixation period, prior to the appearance of the stimulus, resembling a bias factor. This preferential influence of posterior parietal activity on behavior was transient, so that dorsolateral prefrontal activity predicted choice after the appearance of the stimulus. Additionally, reaction time was better predicted by posterior parietal activity. These findings confirm an involvement of both dorsolateral prefrontal and posterior parietal cortex in the bottom-up guidance of visual attention but indicate different roles of the two areas in the guidance of attention and a dynamic time course of their effects, influencing behavior at different stages of the task. PMID:24964224
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
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.
High-resolution OCT: an innovative tool for posterior segment imaging.
Abdallah, Walid F; Olmos de Koo, Lisa C; Abdulkader, Mohamed M; Barnett, Cullen; Chader, Gerald J; Humayun, Mark S
2012-01-01
Optimal management of posterior segment disorders requires a high-resolution and preferably noninvasive imaging tool for better definition of diseases. High-resolution optical coherence tomography can provide noninvasive, high-definition imaging of the posterior segment, allowing earlier diagnosis, better follow-up of chronic cases, and more accurate and timely monitoring of the effect of therapeutic agents. Recent findings suggest an individualized approach to vitreoretinal and choroidal diseases is possible based not only on traditional ophthalmic investigations, but also on high-resolution optical coherence tomography. This innovative tool has the combined advantages of high speed, high resolution, and safe use. PMID:23357319
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, 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...
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, 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...
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
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
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
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
Posterior plica perforation: rare complication of adenotonsillectomy.
Yildirim, Yavuz Selim; Senturk, Erol; Ozturan, Orhan
2014-07-01
Tonsillectomy is one of the most common operations performed by otolaryngologists. Some extraordinary complications of this surgery are massive bleeding, taste perception disorders due to glossopharyngeal nerve damage, hematoma of the mouth floor, jugular vein thrombosis, Grisel syndrome, cervical osteomyelitis, nasopharyngeal stenosis, pulmonary edema, infection, and lingual artery pseudoaneurysm. In this clinical report, an 8-year-old girl presented with a posterior plica perforation after adenotonsillectomy performed 1 week previously and this complication has led to velopharyngeal insufficiency. This rare complication may result from traumatic damage or excessive cauterization of the posterior plica. PMID:25006950
Posterior Ischemic Optic Neuropathy following Herpes Zoster Ophthalmicus
Pakravan, Mohammad; Ahmadieh, Hamid; Kaharkaboudi, Amir-Reza
2009-01-01
Purpose To report a case of posterior ischemic optic neuropathy (PION) following herpes zoster ophthalmicus (HZO). Case Report A 58-year-old woman with history of recent HZO in her right eye presented with acute painless loss of vision in the same eye to no light perception.Examination revealed a positive relative afferent pupillary defect and a normal appearing optic disc. Inflammatory and infiltrative lesions of the optic nerve were ruled out by laboratory and imaging studies. The patient received systemic acyclovir and prednisolone. Three months later, visual acuity improved to counting fingers, but the optic disc became pale and atrophic leading to a presumptive diagnosis of PION.Considering the positive PCR test for varicella zoster virus and the short time interval between the two presentations, HZO was considered as the most probable cause of the optic neuropathy. Conclusion Herpes zoster ophthalmicus can be associated with PION. PMID:23056674
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
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
Abscedation of posterior fossa dermoid cysts
I. H. Tekkök; M. J. Higgins; E. C. G. Ventureyra; S. S. Baeesa
1996-01-01
Dermoid cysts of the posterior fossa are uncommon. When associated with a dermal sinus, these cysts are often diagnosed during early childhood. The main risk of such an association is contamination of the cyst leading to abscedation of the dermoid itself or formation of daughter abscesses within the cerebellar hemisphere. We recently treated a 20-month-old girl who had a congenital
Management of posterior fossa arteriovenous malformations
Almeida, Joao Paulo; Medina, Roberto; Tamargo, Rafael J.
2015-01-01
Background: Posterior fossa arteriovenous malformations (AVMs) are rare vascular lesions, representing 7–15% of all intracranial AVMs. Although less frequent than supratentorial AVMs, they present higher rupture, morbidity, and mortality rates. Microsurgery, radiosurgery, and endovascular neurosurgery are treatment options for obliteration of those lesions. In this paper, we present a critical review of the literature about the management of posterior fossa AVM. Methods: A MEDLINE-based search of articles published between January 1960 and January 2014 was performed. The search terms: “Posterior fossa arteriovenous malformation,” “microsurgery,” “radiosurgery,” and “endovascular” were used to identify the articles. Results: Current data supports the role of microsurgery as the gold standard treatment for cerebellar AVMs. Brainstem AVMs are usually managed with radiotherapy and endovascular therapy; microsurgery is considered in cases of pial brainstem AVMs. Conclusions: Succsseful treatment of posterior fossa AVMs depend on an integrated work of neurosurgeons, radiosurgeons, and endovascular neurosurgery. Although the development of radiosurgery and endovascular techniques is remarkable, microsurgery remains as the gold standard treatment for most of those lesions. PMID:25745586
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
Cerebellar Mutism after Posterior Fossa Surgery
Parker Mickle
1991-01-01
A large midline posterior fossa medulluloblastoma and a cerebellar arteriovenous malformation with associated clot were moved with postoperative mutism. Mutism was immediate and resolved into an ataxic dysarthria with residual mild dysarthria at 3 months. The literature is reviewed, and the clinicopathological and neurophysiological data of cerebellar function in speech are discussed. Acute injury to the midportion of the cerebellum
[Transient blindsight (type 2) after surgery for posterior cerebral artery aneurysm--case report].
Urasaki, Eiichirou; Yamakawa, Yuzo; Yamada, Kiyotada; Fukudome, Takayasu
2008-06-01
In a 47-year-old woman experiencing pulsatile headache, radiological examination revealed a large right posterior cerebral artery (PCA) aneurysm. Preoperative neurological examination showed bilateral papilledema, but no visual disturbance. Cerebral angiography revealed that the aneurysm originated from the ambient segment of the PCA, and the posterior temporal, calcarine, and parieto-occipital arteries were all branched from the aneurysmal dome. Clipping of the feeding PCA trunk was performed via a left subtemporal approach. As a result of left occipital lobe infarction due to calcarine artery occlusion, right upper quadrant hemianopsia appeared after surgery, as confirmed by Goldman's perimetry. Other cerebral infarctions were identified in the junction between the left posterior internal capsule and thalamus, in the left posterior corpus callosum, and in the posterior base of the left temporal lobe due to the occlusion of the posterolateral thalamoperforating, posterior pericallosal, and posterior temporal arteries, respectively. The aneurysm was thrombosed and headache and papilledema subsided. The patient was able to detect the motion of a subject in a blind field, but consciousness of sight was absent. She was able to unconsciously move her finger toward a small penlight, and insert a paper into a slot with variable angles in the blind field. These phenomena disappeared within 4 months of the surgery. The results to forced choice tasks with figures (circle, cross, square, triangle, and star) and colors (red, blue, yellow, and green) were below chance levels. The present case was thus diagnosed as blindsight type 2 (gnosopsia) associated with awareness, probably due to transient activation of the dorsal "what" pathway among numerous visual processes. PMID:18567363
On differentiating the probability of error in multipopular feature selection
NASA Technical Reports Server (NTRS)
Peters, B. C.
1974-01-01
A method of linear feature selection for n dimensional observation vectors which belong to one of m populations is presented. Each population has a known apriori probability and is described by a known multivariate normal density function. Specifically we consider the problem of finding a k x n matrix B of rank k (k n) for which the transformed probability of misclassification is minimized. Providing that the transformed a posterior probabilities are distinct theoretical results are obtained which, for the case k = l, give rise to a numerically tractable formula for the derivative of the probability of misclassification. It is shown that for the two population problem this condition is also necessary. The dependence of the minimum probability of error on the a priori probabilities is investigated. The minimum probability of error satisfies a uniform Lipschitz condition with respect to the a priori probabilities.
Validation of Bayesian posterior distributions using a multidimensional Kolmogorov-Smirnov test
NASA Astrophysics Data System (ADS)
Harrison, Diana; Sutton, David; Carvalho, Pedro; Hobson, Michael
2015-08-01
We extend the Kolmogorov-Smirnov (K-S) test to multiple dimensions by suggesting a R^n ? [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 validation in the real-world astrophysical application of estimating the physical parameters of galaxy clusters parameters from their Sunyaev-Zel'dovich effect in microwave background data. In the latter example, we show that the method can validate the entire Bayesian inference process across a varied population of objects for which the derived posteriors are different in each case.
ERIC Educational Resources Information Center
Rom, Mark Carl
2011-01-01
Grades matter. College grading systems, however, are often ad hoc and prone to mistakes. This essay focuses on one factor that contributes to high-quality grading systems: grading accuracy (or "efficiency"). I proceed in several steps. First, I discuss the elements of "efficient" (i.e., accurate) grading. Next, I present analytical results…
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.
Probability, Nondeterminism and Concurrency
Varacca, Daniele - Laboratoire Preuves, Programmes et Systèmes, Université Paris 7
Probability, Nondeterminism and Concurrency Daniele Varacca PhD Defence BRICS Aarhus, November 24th 2003 Probability, Nondeterminism and Concurrency p.1 #12;Road Map · Motivation · Probability and Nondeterminism · Probability and Concurrency Probability, Nondeterminism and Concurrency p.2 #12;Road Map
Probability Calculus Bayesian Networks
Huang, Jinbo
Probability Calculus Bayesian Networks Logic and Bayesian Networks Part 1: Probability Calculus and Bayesian Networks Jinbo Huang Jinbo Huang Probability Calculus and Bayesian Networks 1/ 31 #12;Probability Reasoning by logical encoding and compilation Jinbo Huang Probability Calculus and Bayesian Networks 2/ 31
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.
Assessment of the posterior malleolus as a restraint to posterior subluxation of the ankle.
Raasch, W G; Larkin, J J; Draganich, L F
1992-09-01
We assessed the function of the posterior malleolus, the anterior tibiofibular ligament, and the fibula with regard to posterior stability of the talus in ten ankles of cadavera. Posteriorly directed loads of as much as 200 newtons were applied. Two groups of ankles were tested; in the first group, three ankles in which the ligamentous and osseous structures were intact were tested after transection of the posterior capsule and after removal of 10, 20, 30, and 40 per cent of the articular surface of the distal end of the tibia from the posterolateral corner. In the second group, seven ankles were tested in the same sequence, but the anterior tibiofibular ligament and the fibula were transected before sectioning of the articular surface. Compared with the results for the intact ankle, the experiments on the first group demonstrated less than one millimeter of additional posterior translation of the talus after removal of as much as 40 per cent of the articular surface. In the second group, in which the anterior tibiofibular ligament and the fibula had been transected, significant posterior translation of the talus (more than three millimeters) occurred after removal of 30 per cent of the articular surface (p < 0.01). This represented a 160 per cent increase in translation compared with that in the intact ankle. PMID:1400549
Arthroscopic approach to the posterior compartment of the knee using a posterior transseptal portal
Ohishi, Tsuyoshi; Takahashi, Masaaki; Suzuki, Daisuke; Matsuyama, Yukihiro
2015-01-01
Arthroscopic surgery of the posterior compartment of the knee is difficult when only two anterior portals are used for access because of the inaccessibility of the back of the knee. Since its introduction, the posterior transseptal portal has been widely employed to access lesions in the posterior compartment. However, special care should be taken to avoid neurovascular injuries around the posteromedial, posterolateral, and transseptal portals. Most importantly, popliteal vessel injury should be avoided when creating and using the transseptal portal during surgery. Purpose of the present study is to describe how to avoid the neurovascular injuries during establishing the posterior three portals and to introduce our safer technique to create the transseptal portal. To date, we have performed arthroscopic surgeries via the transseptal portal in the posterior compartments of 161 knees and have not encountered nerve or vascular injury. In our procedure, the posterior septum is perforated with a 1.5-3.0-mm Kirschner wire that is protected by a sheath inserted from the posterolateral portal and monitored from the posteromedial portal to avoid popliteal vessel injury.
Arthroscopic approach to the posterior compartment of the knee using a posterior transseptal portal.
Ohishi, Tsuyoshi; Takahashi, Masaaki; Suzuki, Daisuke; Matsuyama, Yukihiro
2015-08-18
Arthroscopic surgery of the posterior compartment of the knee is difficult when only two anterior portals are used for access because of the inaccessibility of the back of the knee. Since its introduction, the posterior transseptal portal has been widely employed to access lesions in the posterior compartment. However, special care should be taken to avoid neurovascular injuries around the posteromedial, posterolateral, and transseptal portals. Most importantly, popliteal vessel injury should be avoided when creating and using the transseptal portal during surgery. Purpose of the present study is to describe how to avoid the neurovascular injuries during establishing the posterior three portals and to introduce our safer technique to create the transseptal portal. To date, we have performed arthroscopic surgeries via the transseptal portal in the posterior compartments of 161 knees and have not encountered nerve or vascular injury. In our procedure, the posterior septum is perforated with a 1.5-3.0-mm Kirschner wire that is protected by a sheath inserted from the posterolateral portal and monitored from the posteromedial portal to avoid popliteal vessel injury. PMID:26301179
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 Density Estimation for a Class of On-line Quality Control Models
NASA Astrophysics Data System (ADS)
Dorea, Chang C. Y.; Santos, Walter B.
2011-11-01
On-line quality control during production calls for a periodical monitoring of the produced items according to some prescribed strategy. It is reasonable to assume the existence of internal non-observable variables so that the carried out monitoring is only partially reliable. Under the setting of a Hidden Markov Model (HMM), posterior density estimates are obtained via particle filter type algorithms. Making use of kernel density methods the stable regime densities are approximated and false-alarm probabilities are estimated.
Accurate Finite Difference Algorithms
NASA Technical Reports Server (NTRS)
Goodrich, John W.
1996-01-01
Two families of finite difference algorithms for computational aeroacoustics are presented and compared. All of the algorithms are single step explicit methods, they have the same order of accuracy in both space and time, with examples up to eleventh order, and they have multidimensional extensions. One of the algorithm families has spectral like high resolution. Propagation with high order and high resolution algorithms can produce accurate results after O(10(exp 6)) periods of propagation with eight grid points per wavelength.
Accurate Unlexicalized Parsing
Dan Klein; Christopher D. Manning
2003-01-01
We demonstrate that an unlexicalized PCFG can parse much more accurately than previously shown, by making use of simple, linguistically motivated state splits, which break down false independence assumptions latent in a vanilla treebank grammar. Indeed, its performance of 86.36% (LP\\/LR F PCFG models, and surprisingly close to the current state-of-the-art. This result has potential uses beyond establishing a strong
Presenile dementia diagnosed as posterior cortical atrophy.
Tsunoda, Ayami; Iritani, Shuji; Ozaki, Norio
2011-09-01
Posterior cortical atrophy (PCA) was originally proposed in 1988 based on five cases of dementia presenting characteristic clinical symptoms. The concept of PCA is still not generally accepted. Herein, we present a case of a presenile female with PCA. A 57-year-old woman was brought to the hospital by her older sister. The patient's chief complaints were that she could not drive a car safely and had caused numerous traffic accidents. Construction apraxia and unilateral spatial agnosia were detected by neuropsychological tests. The patient could not write a coherent the letter even though she was well educated. In addition, she demonstrated slight memory disturbance and she needed her sister's support in daily life. Magnetic resonance imaging and single photon emission computed tomography examinations confirmed bilateral posterior atrophy and significant hypoperfusion in the occipital regions. The neuropathological background of PCA remains unclear. Therefore, the concept of PCA should be validated by the accumulation of information from more cases. PMID:21951958
Reversible Posterior Leukoencephalopathy Syndrome Induced by Pazopanib
2012-01-01
Background The reversible posterior leukoencephalopathy syndrome is a clinical/radiological syndrome characterized by headache, seizures, impaired vision, acute hypertension, and typical magnetic resonance imaging findings. There are several reports in the literature that depict its occurrence in cancer patients. The list of common anticancer and supportive care drugs that predispose to reversible posterior leukoencephalopathy syndrome is expanding and includes not only a large number of chemotherapeutic agents but also an increased number of new targeted drugs, particularly angiogenesis inhibitors such as bevacizumab,sorefenib and sunitinib. Pazopanib is an oral tyrosine kinase inhibitor targeting vascular endothelial growth factor receptor, platelet-derived growth factor receptor, and c-Kit which after a positive phase III randomized clinical trial in patients with advanced renal cell cancer received FDA approval for the treatment of advanced renal cell carcinoma. Until now no cases of reversible posterior leukoencephalopathy syndrome induced by pazopanib have been reported. Case report We present the case of a 40 years old female patient with heavily pre-treated metastatic renal cell carcinoma who received pazopanib as salvage treatment. After 21 days of pazopanib therapy the patient referred to the emergency department with epileptic seizure, impaired vision at both eyes and headache. MRI of the brain revealed subcortical oedema at the occipital and parietal lobes bilaterally. She was treated with anticonvulsants, i.v. administration of mannitol and antihypertensives and she recovered completely from her symptoms and was discharged on the tenth hospital day. A brain MRI performed 3 weeks after showed that the subcortical oedema had been subsided. Conclusion In conclusion this is the first case of pazopanib induced reversible posterior leukoencephalopathy syndrome. Although usually reversible, this syndrome is a serious and potentially life threatening adverse effect, if untreated, that should be considered by physicians treating metastatic renal cell carcinoma patients with pazopanib. PMID:23088634
Indocyanine green angiography in posterior uveitis
Agrawal, Rupesh V; Biswas, Jyotirmay; Gunasekaran, Dinesh
2013-01-01
Literature review for indocyanine green angiography and evaluate the role of indocyanine green angiogram (ICGA) in patients with posterior uveitis seen at a tertiary referral eye care centre. Detailed review of the literature on ICGA was performed. Retrospective review of medical records of patients with posterior uveitis and dual fundus and ICGA was done after institutional board approval. Eighteen patients (26 eyes) had serpiginous choroiditis out of which 12 patients had active choroiditis and six patients had healed choroiditis, six patients (12 eyes) had ampiginous choroiditis, six patients (12 eyes) had acute multifocal posterior placoid pigment epitheliopathy, eight patients (10 eyes) had multifocal choroiditis, four patients (eight eyes) had presumed ocular histoplasmosis syndrome, four patients (eight eyes) had presumed tuberculous choroiditis, two patients (four eyes) had multiple evanescent white dot syndrome and two patients (four eyes) had Vogt Koyanagi Harada (VKH) syndrome. The most characteristic feature noted on ICGA was the presence of different patterns of hypofluorescent dark spots, which were present at different stages of the angiogram. ICGA provides the clinician with a powerful adjunctive tool in choroidal inflammatory disorders. It is not meant to replace already proven modalities such as the fluorescein angiography, but it can provide additional information that is useful in establishing a more definitive diagnosis in inflammatory chorioretinal diseases associated with multiple spots. It still needs to be determined if ICGA can prove to be a follow up parameter to evaluate disease progression. PMID:23685486
Califano, L; Salafia, F; Mazzone, S; Melillo, M G; Califano, M
2014-06-01
Posterior canal benign paroxysmal positional vertigo (BPPV) is the most frequent form of BPPV. It is characterized by a paroxysmal positioning nystagmus evoked through Dix-Hallpike and Semont positioning tests. Anterior canal BPPV (AC) is more rare than posterior canal BPPV; it presents a prevalent down beating positioning nystagmus, with a torsional component clockwise for the left canal, counterclockwise for the right canal. Due to the possible lack of the torsional component, it is sometimes difficult to identify the affected ear. An apogeotropic variant of posterior BPPV (APC) has recently been described, characterised by a paroxysmal positional nystagmus in the opposite direction to the one evoked in posterior canal BPPV: the linear component is down-beating, the torsional component is clockwise for the right canal, counter-clockwise for the left canal, so that a contra-lateral anterior canal BPPV could be simulated. During a 16 month period, of 934 BPPV patients observed, the authors identified 23 (2.5%) cases of apogeotropic posterior canal BPPV and 11 (1.2%) cases of anterior canal BPPV, diagnosed using the specific oculomotor patterns described in the literature. Anterior canal BPPV was treated with the repositioning manoeuvre proposed by Yacovino, which does not require identification of the affected side, whereas apogeotropic posterior canal BPPV was treated with the Quick Liberatory Rotation manoeuvre for the typical posterior canal BPPV, since in the Dix-Hallpike position otoliths are in the same position if they come either from the ampullary arm or from the non-ampullary arm. The direct resolution of BPPV (one step therapy) was obtained in 12/34 patients, 8/23 patients with APC and 4/11 patients with AC; canalar conversion into typical posterior canal BPPV, later treated through Quick Liberatory Rotation (two-step therapy), was obtained in 19 patients,14/23 with APC and 5/11 with AC. Three patients were lost to follow-up. Considering the effects of therapeutic manoeuvres, the authors propose a grading system for diagnosis of AC and APC: "certain" when a canalar conversion in ipsilateral typical posterior canal BPPV is obtained; "probable" when APC or AC are directly resolved; "possible" when disease is not resolved and cerebral neuroimaging is negative for neurological diseases. Our results show that the oculomotor patterns proposed in the literature are effective in diagnosing APC and AC, and that APC is more frequent than AC. Both of these rare forms of vertical canal BPPV can be treated effectively with liberatory manoeuvres. PMID:24882928
Detecting Poor Convergence of Posterior Samplers due to Multimodality
West, Mike
Detecting Poor Convergence of Posterior Samplers due to Multimodality Dawn B. Woodard Department that this approach may be in- sufficient when the posterior distribution is multimodalthat lack of convergence due to posterior multimodality can be undetected using the standard convergence diagnostics, including the Gelman
[Spontaneous bilateral posterior capsule rupture in child--case report].
Kanigowska, Krystyna; Gra?ek, Miros?awa; Trzebicka, Agnieszka; Chipczy?ska, Barbara
2007-01-01
Isolated posterior capsule rupture without penetrating injury has rarely been reported. Posterior capsule tears can be preexisting, spontaneous or intrasurgical. Authors report a case of progressing bilateral cataract in 3 months old boy, caused by posterior capsule rupture. Rapidly developing cataract with intumescent lens material in vitreous cavity required surgical procedure: pars plana lensectomy and vitrectomy in both eyes. PMID:18260293
Physical Probability Patrick Maher
Fitelson, Branden
Physical Probability Patrick Maher University of Illinois at Urbana-Champaign October 13, 2007 ABSTRACT. By "physical probability" I mean the empirical concept of probability in or- dinary language-extreme physical probabilities are compatible with determin- ism. Two principles, called specification
Physical Probability Patrick Maher
Maher, Patrick
Physical Probability Patrick Maher September 4, 2008 ABSTRACT. By "physical probability" I mean the empirical concept of probability in or- dinary language. It can be represented as a function of an experiment type and an outcome type, which explains how non-extreme physical probabilities are compatible
1 Introduction to Probability Professor Douglas H. Jones Overview This is a graduate level introduction to probability theory with the goal of providing a thorough treatment of basic and classical probability theory. Topics include an introduction to probability measures (-algebras, set theory
Hosseini, S.; Rusnak, J. J.
1987-01-01
changei1in temperature (100-1000 ohms/oc) prov~de excellent resol ution. However, therm~s? ters are unstable and non-linear and ftlm deposits from the working fluid w~ll change their calibration. They can a~so d r iftIt0 2 0 F every yea r. As ares ut... and stable and ' he best known commercially available lin,. ar devices. For the most accurate 'TU measurement systems, 1000 ohm RTD's 're used because they provide greater sign'l to-noise ratios and greater sensitivity~ Fur~hermore, lQOO-~bm FLatin...
Asymptotic relationships between posterior probabilities and pvalues using the hazard rate
Gómez Villegas, Miguel Ángel
15. Keywords: Hazard rate, Pvalue, Point null hypothesis, tail-orderings. 1. Introduction In testing a point null hypothesis, it is well-known that the discrepancy between the classical p-value, from now to the null hypothesis is related to the prior density over the alternative hypothesis. The point is to work
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 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
A Short History of Posterior Dynamic Stabilization
Gomleksiz, Cengiz; Sasani, Mehdi; Oktenoglu, Tunc; Ozer, Ali Fahir
2012-01-01
Interspinous spacers were developed to treat local deformities such as degenerative spondylolisthesis. To treat patients with chronic instability, posterior pedicle fixation and rod-based dynamic stabilization systems were developed as alternatives to fusion surgeries. Dynamic stabilization is the future of spinal surgery, and in the near future, we will be able to see the development of new devices and surgical techniques to stabilize the spine. It is important to follow the development of these technologies and to gain experience using them. In this paper, we review the literature and discuss the dynamic systems, both past and present, used in the market to treat lumbar degeneration. PMID:23326674
Anterior ischemia after posterior segment surgery.
Bronner, Guri; Zarbin, Marco A; Bhagat, Neelakshi
2004-12-01
Anterior segment ischemia is a rare complication of posterior segment surgery with a broad spectrum of presentations. Most frequently, it follows a mild self-limited course. Cases that are more prominent usually result from a co-incidence of precipitating factors. Recognition of precipitating factors and appropriate action can avoid anterior segment ischemia. Management includes nonspecific steps, such as topical medications (ie, corticosteroids and cycloplegics) and face-mask and eye-mask oxygen delivery, as well as specific steps related to the underlying cause (eg, removal of an encircling scleral buckle). PMID:15533747
Reversible posterior encephalopathy syndrome secondary to sunitinib.
Costa, Ricardo; Costa, Rubens; Costa, Renata; Junior, Gilberto Moura de Brito; Cartaxo, Henrique Queiroz; de Barros, Alex Caetano
2014-01-01
Reversible posterior leukoencephalopathy syndrome (RPLS) is clinical radiologic condition associated with neurological symptoms and cerebral white matter edema. It has been associated with uncontrolled hypertension, eclampsia, immunosuppressants, and more recently the use of antiangiogenic drugs. Sunitinib is an inhibitor of the vascular endothelial growth factor receptor widely used in the treatment of metastatic renal cell carcinoma (RCC). We report a rare case of RPLS occurring on therapy with sunitinib in a patient with RCC. Our aim is to highlight the importance of considering RPLS as a diagnostic possibility and to hold sunitinib for RCC patients presenting with neurologic symptoms. PMID:24900933
Accurate quantum chemical calculations
NASA Technical Reports Server (NTRS)
Bauschlicher, Charles W., Jr.; Langhoff, Stephen R.; Taylor, Peter R.
1989-01-01
An important goal of quantum chemical calculations is to provide an understanding of chemical bonding and molecular electronic structure. A second goal, the prediction of energy differences to chemical accuracy, has been much harder to attain. First, the computational resources required to achieve such accuracy are very large, and second, it is not straightforward to demonstrate that an apparently accurate result, in terms of agreement with experiment, does not result from a cancellation of errors. Recent advances in electronic structure methodology, coupled with the power of vector supercomputers, have made it possible to solve a number of electronic structure problems exactly using the full configuration interaction (FCI) method within a subspace of the complete Hilbert space. These exact results can be used to benchmark approximate techniques that are applicable to a wider range of chemical and physical problems. The methodology of many-electron quantum chemistry is reviewed. Methods are considered in detail for performing FCI calculations. The application of FCI methods to several three-electron problems in molecular physics are discussed. A number of benchmark applications of FCI wave functions are described. Atomic basis sets and the development of improved methods for handling very large basis sets are discussed: these are then applied to a number of chemical and spectroscopic problems; to transition metals; and to problems involving potential energy surfaces. Although the experiences described give considerable grounds for optimism about the general ability to perform accurate calculations, there are several problems that have proved less tractable, at least with current computer resources, and these and possible solutions are discussed.
Hydatidosis of the liver and posterior mediastinum
Quail, Jacob F; Gramins, Daniel L; Dutton, William D
2014-01-01
Introduction Cystic echinococcus (CE) is an endemic zoonosis secondary to infection by the larval form of the cestode Echinococcus granulosus. An intermediate host, humans enter the organism’s life cycle by exposure to infected canid feces. The liver is the most common location of CE while mediastinal hydatid cysts are rarely reported. Presentation of case We report a case of synchronous CE of the liver and posterior mediastinum treated sequentially using chemotherapy, percutaneous aspiration with injection of a scolicidal agent and re-aspiration (PAIR) and then staged minimally-invasive surgeries. Discussion Synchronous CE involving the liver and posterior mediastinum is rare. The treatment of hydatid liver and mediastinal disease is multimodal including chemotherapy, percutaneous and laparoscopic or open surgical interventions. One option for controlled puncture of hepatic and mediastinal CE includes PAIR followed by surgery. Conclusion The sequential use of chemotherapy and PAIR followed by surgery provides another treatment strategy for management of CE. We believe this strategy may be used safely in locations without endemic CE, including most regions of the United States. PMID:25562598
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
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
2014-04-01
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
Posterior consistency in conditional distribution estimation
Pati, Debdeep; Dunson, David B.; Tokdar, Surya T.
2014-01-01
A wide variety of priors have been proposed for nonparametric Bayesian estimation of conditional distributions, and there is a clear need for theorems providing conditions on the prior for large support, as well as posterior consistency. Estimation of an uncountable collection of conditional distributions across different regions of the predictor space is a challenging problem, which differs in some important ways from density and mean regression estimation problems. Defining various topologies on the space of conditional distributions, we provide sufficient conditions for posterior consistency focusing on a broad class of priors formulated as predictor-dependent mixtures of Gaussian kernels. This theory is illustrated by showing that the conditions are satisfied for a class of generalized stick-breaking process mixtures in which the stick-breaking lengths are monotone, differentiable functions of a continuous stochastic process. We also provide a set of sufficient conditions for the case where stick-breaking lengths are predictor independent, such as those arising from a fixed Dirichlet process prior. PMID:25067858
Posterior Interosseous Nerve Syndrome from Thermal Injury
Singh, Vijay A.; Michael, Rami E.; Dinh, Duy-Bao P.; Bloom, Scott; Cooper, Michael
2014-01-01
Background. Due to anatomical proximity to bone, the radial nerve is the most frequently injured major nerve of the upper extremity, frequently secondary to fractures (Li et al. (2013)). We describe an incidence when a branch of the radial nerve is injured as a result of a thermal injury. Observation. Radial nerve injury can occur anywhere along the anatomical course with varied etiologies, but commonly related to trauma. The most frequent site is in the proximal forearm involving the posterior interosseous branch. However, problems can occur at the junction of the middle and proximal thirds of the humerus and wrist radially. When the radial nerve is injured by a burn, a new rehabilitation dynamic arises. Not only does one agonize about the return of nerve function but also fret about the skin grafts that replaced the devitalized tissue housing that compartment. Discussion. Although posterior interosseous nerve syndrome has been described in the context of many different etiologies, it has not previously been discussed in relation to burn injuries. In this case, not only did the patient's rehabilitation involve aggressive therapy for return of sensation and function of the arm, but also prevention of contracture normally seen in replacement of full thickness burns. PMID:24707432
Elastic properties of human posterior eye.
Chen, Kinon; Rowley, Adrian P; Weiland, James D; Humayun, Mark S
2014-06-01
This study examines the elastic properties of the human posterior retina, choroid, and sclera. Twenty-four human eyes from 30- to 74-year-old donors were obtained from an eye bank. Vertically and horizontally oriented tissue strips of the retina, choroid, and sclera (ideally n?=?12 in each group) were harvested from the posterior eyes. Their thicknesses were estimated optically. The samples were stretched at 1 mm/s in 37°C saline. Stress and strain were obtained from the mechanical tests, and then the transition stress, transition strain, toe modulus, and heel modulus were calculated. Statistical analysis was performed for comparison between groups. Linear regression analyses were used to explore the relationship between the mechanical parameters and age. We found that the stress-strain relationship of the retina, choroid, and sclera were nonlinear. Except for the retinal transition strain (p?=?0.0124), no statistical difference was found between the vertical and horizontal meridian in the mechanical parameters (p?>?0.05). Furthermore, weak relationship was observed between some of the mechanical parameters and the donors' age. Our results suggest that there is significant anisotropy in the retina, and mechanical properties of each layer may change with age. PMID:23852923
Extradural dermoid tumours of the posterior fossa
Martinez-Lage, J; Ramos, J; Puche, A; Poza, M
1997-01-01
?? Dermoid tumours in children usually occur in two locations: at the anterior fontanelle and on the occipital squama. An exceptional site of origin for a posterior fossa dermoid cyst is the extradural space. There are only six previous cases of this situation reported in the literature. A series of 103 subscalp and calvarial masses in children were reviewed and three children are reported with extradural dermoids of the posterior fossa, which communicated with the skin through midline occipital dermal sinuses. All three children were seen after the rapid growth or the formation of an abscess in a previously noted occipital subcutaneous mass present since birth. Although computed tomography or magnetic resonance imaging showed the dermal sinus and the intracranial tumour, these studies were unable to ascertain the intradural or extradural nature of the tumours, their exact origin only being established at operation. Histopathological study showed preclinical signs of infection in the two patients that had not yet formed an abscess. It is suggested that early neurosurgical treatment of these neoplasms should be done to prevent the development of severe intracranial infection. The previously reported simplicity of surgical removal of occipital extradural dermoids was not confirmed in this series.?? PMID:9487967
The posterior calf fascial free flap.
Walton, R L; Matory, W E; Petry, J J
1985-12-01
Six posterior calf fascial free flaps were employed to reconstruct defects of the upper and lower extremities. One flap failed due to a constricting dressing. Two flaps sustained partial loss secondary to bleeding and hematoma formation. One flap dehisced at the distal suture line due to mobility of an underlying fracture. All surviving flaps eventually healed and resulted in stable, thin coverage. Donor-site morbidity has been minimal. Shortcomings of this flap model have been defined in the peculiarities of its thinness, diffuse vascular oozing, the extent of the vascular territory, and in postoperative monitoring. These problems are analyzed and recommendations for their resolution are presented. Fascia represents a unique tissue which offers an exciting new dimension in the reconstruction of certain defects--particularly those in which thinness is a desirable option. In the posterior calf model, the inclusion of fat represents an alternative modification that allows the surgeon to tailor the design to a variety of problems where fascia alone is too thin and a cutaneous flap is too thick. This concept may find its greatest application in wounds involving the hand or foot. We believe that this and other fascial flap prototypes may offer an ideal solution for reconstruction of major wounds of the extremities. PMID:3906718
Stanford University
by the assumptions they make. Using published studies of navigation system reliability, this paper develops a prior as multi-step integrity algorithms which use Bayesian updating to generate posterior failure probabilities which use prior as well as current measurements. Bayesian updating (starting with the prior probability
Edinburgh, University of
that feedforward net works may be used to estimate local output probabilities in hidden Markov model (HMM INTRODUCTION Previous investigations, both theoretical and experimental, have indicated that feed probabil ity of incorrect classes in addition to increasing the posterior probability of the correct class
ERIC Educational Resources Information Center
Bailey, David H.
2000-01-01
Some of the most impressive-sounding criticisms of the conventional theory of biological evolution involve probability. Presents a few examples of how probability should and should not be used in discussing evolution. (ASK)
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...
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.
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
Bayesian Probability Patrick Maher
Fitelson, Branden
the agent's evidence. 1 Introduction Bayesian decision theory, in its usual form, asserts that rationalBayesian Probability Patrick Maher University of Illinois at Urbana-Champaign November 24, 2007 ABSTRACT. "Bayesian probability" here means the concept of probability used in Bayesian decision theory
NSDL National Science Digital Library
Dr. Marco Taboga
2010-08-23
This is a free digital textbook on probability theory. It is ideal for a second-year undergraduate course in probability theory. It aims to fill the gap between elementary treatments of probability theory and more advanced treatments based on measure theory.
Interactive Applet: Probability Distribution
NSDL National Science Digital Library
This applet, created by McGraw-Hill High Education, is designed to help students understand probability distributions compared to theoretical values by simulating tossing coins. It allows you to compare the theoretical probabilities based upon the classical probability theory with the observed relative frequencies. It accompanies "Statistical Techniques in Business and Economics," but does not require use of the text.
ERIC Educational Resources Information Center
Edwards, William F.; Shiflett, Ray C.; Shultz, Harris
2008-01-01
The mathematical model used to describe independence between two events in probability has a non-intuitive consequence called dependent spaces. The paper begins with a very brief history of the development of probability, then defines dependent spaces, and reviews what is known about finite spaces with uniform probability. The study of finite…
Posterior cruciate ligament rehabilitation: how slow should we go?
Fanelli, Gregory C
2008-02-01
Outcomes after posterior cruciate ligament (PCL) reconstructive surgery have historically been inferior to outcomes after reconstruction of the anterior cruciate ligament (ACL). As such, some surgeons may be reluctant to recommend reconstruction of the PCL. However, recent technologic advances have substantially improved PCL reconstructive surgical outcomes. These advances include better understanding of PCL diagnosis and surgical indications; recognition of the need for repair or reconstruction of associated injuries, especially injuries to the posterolateral and posteromedial corners of the knee; PCL-specific surgical instruments including mechanical tensioning devices to restore anatomic tibial step-off; improved graft fixation techniques including primary and backup methods of fixation; use of strong graft material including advances in the procurement, processing, and usage of allograft tissue; improved surgical techniques; and advances in the understanding of knee ligament structure and biomechanics, resulting in more accurate surgical tunnel placement, achieving anatomic graft insertion sites while minimizing graft bending. Today, PCL reconstructive surgery often results in excellent function with a return to the patient's preinjury level of activity. In contrast to accelerated rehabilitation after ACL reconstructive surgery, slow and deliberate postoperative rehabilitation is recommended to allow early healing to occur after PCL reconstructive surgery. PMID:18251084
List of Topics Probability Basic Course I. Probability Space
List of Topics Probability Basic Course I. Probability Space Events, probability, conditional probability, independence [Measurable spaces and measures] II. Random Variables Discrete random variables and continuous random variables in one or more dimensions, probability distribution function, independent random
Dynamical Simulation of Probabilities
NASA Technical Reports Server (NTRS)
Zak, Michail
1996-01-01
It has been demonstrated that classical probabilities, and in particular, probabilistic Turing machine, can be simulated by combining chaos and non-Lipschitz dynamics, without utilization of any man-made devices(such as random number generators). Self-orgainizing properties of systems coupling simulated and calculated probabilities and their link to quantum computations are discussed. Special attention was focused upon coupled stochastic processes, defined in terms of conditional probabilities, for which joint probability does not exist. Simulations of quantum probabilities are also discussed.
MARKOV CHAIN MONTE CARLO POSTERIOR SAMPLING WITH THE HAMILTONIAN METHOD
K. HANSON
2001-02-01
The Markov Chain Monte Carlo technique provides a means for drawing random samples from a target probability density function (pdf). MCMC allows one to assess the uncertainties in a Bayesian analysis described by a numerically calculated posterior distribution. This paper describes the Hamiltonian MCMC technique in which a momentum variable is introduced for each parameter of the target pdf. In analogy to a physical system, a Hamiltonian H is defined as a kinetic energy involving the momenta plus a potential energy {var_phi}, where {var_phi} is minus the logarithm of the target pdf. Hamiltonian dynamics allows one to move along trajectories of constant H, taking large jumps in the parameter space with relatively few evaluations of {var_phi} and its gradient. The Hamiltonian algorithm alternates between picking a new momentum vector and following such trajectories. The efficiency of the Hamiltonian method for multidimensional isotropic Gaussian pdfs is shown to remain constant at around 7% for up to several hundred dimensions. The Hamiltonian method handles correlations among the variables much better than the standard Metropolis algorithm. A new test, based on the gradient of {var_phi}, is proposed to measure the convergence of the MCMC sequence.
Predicted probabilities' relationship to inclusion probabilities.
Fang, Di; Chong, Jenny; Wilson, Jeffrey R
2015-05-01
It has been shown that under a general multiplicative intercept model for risk, case-control (retrospective) data can be analyzed by maximum likelihood as if they had arisen prospectively, up to an unknown multiplicative constant, which depends on the relative sampling fraction. (1) With suitable auxiliary information, retrospective data can also be used to estimate response probabilities. (2) In other words, predictive probabilities obtained without adjustments from retrospective data will likely be different from those obtained from prospective data. We highlighted this using binary data from Medicare to determine the probability of readmission into the hospital within 30 days of discharge, which is particularly timely because Medicare has begun penalizing hospitals for certain readmissions. (3). PMID:25790398
Mature teratoma of the posterior mediastinum: report of a case.
Ibi, Takayuki; Hirai, Kyoji; Takeuchi, Shingo; Bessho, Ryuzo; Kawamoto, Masashi; Shuji, Haraguchi; Koizumi, Kiyoshi; Shimizu, Kazuo
2013-11-01
Mediastinal teratoma generally arises in the anterior mediastinum. Posterior mediastinal teratomas have been rarely reported to date, especially in adults. We report a case of posterior mediastinal teratoma in a 57-year-old woman. The pre-operative diagnostic work-up revealed a posterior mediastinal tumor with calcification and fluid components. The tumor, adhering to the descending aorta, was radically removed through video-assisted thoracic surgery. Histological examination was concluded for a mature teratoma with cystic change. The imaging features of posterior mediastinal teratomas are identical to those in the anterior mediastinum, except for their location. To be different from anterior mediastinal teratomas, benign teratomas in the posterior mediastinum are often involved with a major surrounding structure, including aorta, chest wall, and esophagus. When a posterior mediastinal tumor has the typical features of a mature teratoma in the pre-operative findings, the adhesion to the surrounding structure should be considered. PMID:23104458
Iodine-125 radiation of posterior uveal melanoma
Packer, S.
1987-12-01
Twenty-eight cases of posterior choroidal melanoma were treated with iodine-125 in gold eye plaques. Eleven cases were located within 3.0 mm of the optic nerve (group A), nine were within 3.0 mm of the fovea (group B), and eight were within 3.0 mm of the optic nerve and fovea (group C). The mean follow-up of group A was 46.3 months; group B, 25.5 months; and group C, 42.7 months. Complications included macular edema, cataract and tumor growth. Visual acuity remained within two lines of that tested preoperatively for 4 of 11 patients in group A, 4 of 9 in group B, and 5 of 8 in group C. These results with iodine-125 suggest it as an appropriate treatment for patients with choroidal melanoma located near optic nerve and/or macula.
New Techniques for Drug Delivery to the Posterior Eye Segment
Esther Eljarrat-Binstock; Jacob Pe’er; Abraham J. Domb
2010-01-01
Ocular drug delivery has become an increasingly important field of research especially when treating posterior segment diseases\\u000a of the eye, such as age-related macular degeneration, diabetic retinopathy, posterior uveitis and retinitis. These diseases\\u000a are the leading causes of vision loss in developed countries which require repeated long-term administration of therapeutic\\u000a agents. New drugs for the medication of the posterior ocular
Probability Introducation Probabilistic Graphical Models
Shi, Qinfeng "Javen"
Probability Introducation Probabilistic Graphical Models Lecture 7: PGM -- Representation Qinfeng Lecture 7: PGM -- Representation #12;Probability Introducation Probabilistic Graphical Models Table of Contents I 1 Probability Introducation Probability space Conditional probability Random Variables
Drug delivery to the posterior segment of the eye.
Fischer, Naomi; Narayanan, Raja; Loewenstein, Anat; Kuppermann, Baruch D
2011-01-01
Drug delivery into the posterior segment of the eye is complicated by the presence of the blood-ocular barrier. Strategies for delivering drugs to the posterior segment include systemic administration, modification of the blood-eye barrier, and local drug delivery. Recently, new topical treatments have emerged for the treatment of posterior eye disease. Iontophoretic, juxtascleral, and intravitreal routes can be used to achieve therapeutic levels in the posterior segment. Extended-release intravitreal drug delivery systems can achieve sustained therapeutic levels with the goal of providing a prolonged clinical benefit. PMID:23264325
Drug delivery to the posterior segment of the eye.
Kuppermann, Baruch D; Loewenstein, Anat
2010-01-01
Drug delivery into the posterior segment of the eye is complicated by the existence of the blood-ocular barrier. Strategies for delivering drugs to the posterior segment include systemic administration, modification of the barrier, and local drug delivery (including transcorneal, transscleral, and intravitreal). Recently, new topical treatments have emerged for the treatment of posterior eye disease. Iontophoretic, juxtascleral, and intravitreal routes can be used to achieve therapeutic levels in the posterior segment. Extended-release intravitreal drug delivery systems can achieve sustained therapeutic levels with the goal of providing a prolonged clinical benefit. PMID:20703044
Missing posterior teeth and risk of temporomandibular disorders.
Wang, M Q; Xue, F; He, J J; Chen, J H; Chen, C S; Raustia, A
2009-10-01
There is disagreement about the association between missing posterior teeth and the presence of temporomandibular disorders (TMD). Here, the purpose was to investigate whether the number of missing posterior teeth, their distribution, age, and gender are associated with TMD. Seven hundred and forty-one individuals, aged 21-60 years, with missing posterior teeth, 386 with and 355 without TMD, were included. Four variables-gender, age, the number of missing posterior teeth, and the number of dental quadrants with missing posterior teeth-were analyzed with a logistic regression model. All four variables-gender (OR = 1.59, men = 1, women = 2), age (OR = 0.98), the number of missing posterior teeth (OR = 0.51), and the number of dental quadrants with missing posterior teeth (OR = 7.71)-were entered into the logistic model (P < 0.01). The results indicate that individuals who lose posterior teeth, with fewer missing posterior teeth but in more quadrants, have a higher prevalence of TMD, especially young women. PMID:19783804
NASA Astrophysics Data System (ADS)
Zhao, Xiao-mei; Xie, Dong-fan; Li, Qi
2015-02-01
With the development of intelligent transport system, advanced information feedback strategies have been developed to reduce traffic congestion and enhance the capacity. However, previous strategies provide accurate information to travelers and our simulation results show that accurate information brings negative effects, especially in delay case. Because travelers prefer to the best condition route with accurate information, and delayed information cannot reflect current traffic condition but past. Then travelers make wrong routing decisions, causing the decrease of the capacity and the increase of oscillations and the system deviating from the equilibrium. To avoid the negative effect, bounded rationality is taken into account by introducing a boundedly rational threshold BR. When difference between two routes is less than the BR, routes have equal probability to be chosen. The bounded rationality is helpful to improve the efficiency in terms of capacity, oscillation and the gap deviating from the system equilibrium.
NASA Astrophysics Data System (ADS)
Lee, Chunghyoung
The dissertation lays out a conceptual framework for measurements equipped with explicit definitions and characterizations of important concepts and elements related to measurement. Its key concepts are: a measurement is 'used' when a value is ascribed to the measured observable based on its outcome; if a measurement reveals the value of the measured observable possessed by the object system before/after the measurement, then it is used 'retrospectively'/'prospectively'; a measurement is used 'collectively' if its outcome is used only as an element of a collection of outcomes of similar measurements to ascribe some (usually statistical) property to the object system; when a measurement is used 'individualistically', its outcome is enough to ascribe a property to its individual object system. The importance and usefulness of the conceptual framework are demonstrated at two levels. Firstly, the conceptual framework is applied to analyze electron double-slit experiments and Heisenberg's uncertainty principle, yielding a more accurate and better understanding of them. Secondly, a theoretical framework is developed for measurements in quantum mechanics, in which quantum measurement processes are characterized with only widely accepted assumptions about measuring apparatuses, and with respect to which the following claims are made and justified: First, there is more than one way to determine the measured observable of a measurement depending on how the quantum measurement is used. The satisfaction of so-called "probability reproducibility condition," which many take as the unique criterion for selecting measured observables, is adequate only for the collective & retrospective use of measurements, but inadequate for the individualistic & prospective use. Second, the individualistic & prospective use of quantum measurements is dispensable (but not forbidden), while the collective & retrospective use of measurements is essential to quantum mechanics as an empirical science. Third, the establishment of perfect value-correlation is a very plausible criterion for selecting measured observables, when measurements are used individualistically & prospectively. And the consistency of posterior value ascriptions based on the principle is guaranteed. Finally, this approach to posterior value ascription yields very nice motivations for the modal interpretation of quantum mechanics.
Yamamoto, Junichi
2015-07-01
Clipping of a posterior projecting large posterior communicating aneurysm via transsylvian anterior temporal approach is presented. To expose and clip this large aneurysm, retraction of the temporal lobe is required via the conventional pterional approach. In this video, we demonstrate microsurgical techniques as to how to dissect and mobilize the sylvian veins as well as a bridging vein to the sphenoparietal sinus, and the middle cerebral artery branches to the frontal lobe side. After the microsurgical dissection, a wide anteriolateral temporal space is obtained without significant temporal lobe retraction. The aneurysm was completely obliterated via this approach. The video can be found here: http://youtu.be/vU9Nxm7Yn-A. PMID:26132613
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.
Predicting low-probability/high-consequence events
Martz, H.F.; Bryson, M.C.
1982-01-01
PRAs often require quantification of the probabilities of various low-probability events, such as accident-initiating events and hardware-fault events. A two-stage Bayes/empirical Bayes data pooling procedure is presented for use in combining as many as five different types of relevant data. A Poisson model is assumed for the event in question. Empirical Bayes methods are used to determine the population variability curve, while Bayesian methods are used to specialize this curve to the specific event in question. The procedure is illustrated by an example in which we estimate the probability of failure of a hypothetical large dam based on (1) a deductive event-tree-type analysis of the probability, (2) historical US dam failure data, (3) the opinions of a committee of several dam experts, and (4) the operating history for the dam in question. A Stage-2 posterior distribution is produced which incorporates these data sources. Similar distributions are produced for various combinations of data types and used to assess the contribution of each data source.
NASA Astrophysics Data System (ADS)
Beechler, B. E.; Vukicevic, T.; Weiss, J. B.
2008-12-01
In this study, the relationship between data assimilation solutions and nonlinear model properties together with observational constraint is analyzed using a numerical technique based on the inverse problem theory formulated by Mosegaard and Tarantola. By this theory, the inverse problem and solution are defined via convolution and conjunction of probability density functions (pdfs) that represent stochastic information obtained from the model, observations and prior knowledge in a joint multidimensional space. This theory provides an explicit analysis of the nonlinear model function, together with information about uncertainties in the model, observations, and prior knowledge through construction of the joint probability density, from which marginal posterior solution functions can then be evaluated. The numerical analysis technique derived from the theory computes the component probability density functions in discretized form via a combination of function mapping on a discrete grid in the model and observation phase space, and sampling from known parametric distributions. This numerical diagnostic analysis technique was first demonstrated in Vukicevic and Posselt (2008) on examples of two well known simplified models of Atmospheric physics: Damped oscillations and Lorenz' 3-component model of dry cellular convection. In the current study the diagnostic analysis of the controls of posterior pdf in data assimilation is performed using a beta plane quasi- geostrophic numerical model. The control parameter space in the model consists of coefficients of two- dimensional Fourier decomposition of stream function fields within regions of unstable dynamical modes. The impact of assumed modeling errors and spatial and temporal distribution of observations on the posterior multi dimensional pdf is studied to evaluate conditions which render this pdf uni-modal. The validity of the Gaussian approximation is then evaluated.
Paratrooper's Ankle Fracture: Posterior Malleolar Fracture
Young, Ki Won; Cho, Jae Ho; Kim, Hyung Seuk; Cho, Hun Ki; Lee, Kyung Tai
2015-01-01
Background We assessed the frequency and types of ankle fractures that frequently occur during parachute landings of special operation unit personnel and analyzed the causes. Methods Fifty-six members of the special force brigade of the military who had sustained ankle fractures during parachute landings between January 2005 and April 2010 were retrospectively analyzed. The injury sites and fracture sites were identified and the fracture types were categorized by the Lauge-Hansen and Weber classifications. Follow-up surveys were performed with respect to the American Orthopedic Foot and Ankle Society ankle-hindfoot score, patient satisfaction, and return to preinjury activity. Results The patients were all males with a mean age of 23.6 years. There were 28 right and 28 left ankle fractures. Twenty-two patients had simple fractures and 34 patients had comminuted fractures. The average number of injury and fractures sites per person was 2.07 (116 injuries including a syndesmosis injury and a deltoid injury) and 1.75 (98 fracture sites), respectively. Twenty-three cases (41.07%) were accompanied by posterior malleolar fractures. Fifty-five patients underwent surgery; of these, 30 had plate internal fixations. Weber type A, B, and C fractures were found in 4, 38, and 14 cases, respectively. Based on the Lauge-Hansen classification, supination-external rotation injuries were found in 20 cases, supination-adduction injuries in 22 cases, pronation-external rotation injuries in 11 cases, tibiofibular fractures in 2 cases, and simple medial malleolar fractures in 2 cases. The mean follow-up period was 23.8 months, and the average follow-up American Orthopedic Foot and Ankle Society ankle-hindfoot score was 85.42. Forty-five patients (80.36%) reported excellent or good satisfaction with the outcome. Conclusions Posterior malleolar fractures occurred in 41.07% of ankle fractures sustained in parachute landings. Because most of the ankle fractures in parachute injuries were compound fractures, most cases had to undergo surgical repairs. PMID:25729514
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
Posterior Simulation for Feed Forward Neural Network Models
West, Mike
to difficult computational problems, stemming from non normality and multimodality of posterior distributions sampling. Multimodality issues have predated discussions in neu ral network research, see e.g. Ripley (1994), of which FFNN's are a special case. There are three main reasons for multimodality of posterior
Experimental posterior uveitis. I: A clinical, angiographic, and pathological study
M R Stanford; E C Brown; E Kasp; E M Graham; M D Sanders; D C Dumonde
1987-01-01
The clinical, angiographic, and histopathological features of experimental posterior uveitis in the black hooded Lister rat are described. This mild form of experimental allergic uveoretinitis (EAU) is induced by sensitisation with retinal S antigen in Freund's complete adjuvant, and the inflammation produced is confined to the posterior segment of the eye. This allows for the first time precise photographic and
POPE: Post Optimization Posterior Evaluation of Likelihood Free Models
Welling, Max
1 POPE: Post Optimization Posterior Evaluation of Likelihood Free Models Edward Meeds1 , Michael of scientists we applied POPE to two important biological simulators: a fast and stochastic simulator of stem Posterior Evaluation" (POPE) is different from standard ABC [4, 5, 6] in that standard ABC compares
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
Reconfigured sigmoid colon neourethra: substitution of refractory posterior urethral stricture.
Lee, Young Tae; Cho, Taek Woo; Jeong, Hee Seong; Lee, Yong Kyu; Hong, Young Kwon
2005-01-01
The repair of extensive posterior urethral stricture often poses a therapeutic dilemma, especially when the urethral defect is too extensive to be repaired with traditional methods and the stricture portion has a poor blood supply. This report details the successful substitution of an extensive posterior urethral stricture using a reconfigured sigmoid colon neourethra. PMID:15667883
Bayes' Theorem: Conditional Probabilities
NSDL National Science Digital Library
Lowry, Richard
To perform calculations using Bayes' theorem, enter the probability for one or the other of the items in each of the following pairs (the remaining item in each pair will be calculated automatically). A probability value can be entered as either a decimal fraction such as .25 or a common fraction such as 1/4
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.
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.
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
Fitelson, Branden
Hume, Induction, and Probability Peter J.R. Millican The University of Leeds Department is to understand Hume's famous argument concerning induction, and to appraise its success in establishing its from which a potential justification of induction could begin. The principles of probability theory
Ganglion cyst of the posterior cruciate ligament
Ahmed, F; Ibrahim, S A; Soliman, A; Khirat, S
2010-01-01
A ganglion is a fluid cyst with a myxoid matrix that arises close to the tendons and joints. Its occurrence inside a joint is rare. Among the various pathological conditions producing impairment of the knee function, ganglia of the cruciate ligaments are quite rare. It may be painful or asymptomatic. Some patients may have a trauma history. Ganglia may mimic intra-articular lesions like tears of the anterior cruciate ligament (ACL) or meniscus. Ganglia, though commonly arise from the ACL, can also arise from other structures such as the posterior cruciate ligament (PCL) or meniscus. Ganglia are typically treated by arthroscopic excision and debridement. We report a case of ganglion of the PCL in a 28-year-old man; the lesion was incidentally discovered during ACL reconstruction with double bundle (Rigid fix technique). The patient underwent arthroscopic excision of the ganglion. At the end of 1-year follow-up the patient was pain free; a full range of motion of his right knee was restored, and he returned to his preinjury sport activity. PMID:22767478
Abnormal visual phenomena in posterior cortical atrophy.
Crutch, Sebastian J; Lehmann, Manja; Gorgoraptis, Nikos; Kaski, Diego; Ryan, Natalie; Husain, Masud; Warrington, Elizabeth K
2011-01-01
Individuals with posterior cortical atrophy (PCA) report a host of unusual and poorly explained visual disturbances. This preliminary report describes a single patient (CRO), and documents and investigates abnormally prolonged colour afterimages (concurrent and prolonged perception of colours complimentary to the colour of an observed stimulus), perceived motion of static stimuli, and better reading of small than large letters. We also evaluate CRO's visual and vestibular functions in an effort to understand the origin of her experience of room tilt illusion, a disturbing phenomenon not previously observed in individuals with cortical degenerative disease. These visual symptoms are set in the context of a 4-year longitudinal neuropsychological and neuroimaging investigation of CRO's visual and other cognitive skills. We hypothesise that prolonged colour after-images are attributable to relative sparing of V1 inhibitory interneurons; perceived motion of static stimuli reflects weak magnocellular function; better reading of small than large letters indicates a reduced effective field of vision; and room tilt illusion effects are caused by disordered integration of visual and vestibular information. This study contributes to the growing characterisation of PCA whose atypical early visual symptoms are often heterogeneous and frequently under-recognised. PMID:20818540
A rare posterior cranial fossa tumor.
Nandeesh, Bevinahalli N; Chabra, Manmeet Singh; Babu, Manjaly K; Chand, Ashish K
2012-01-01
Among tumors of the central nervous system, tumors of the mixed glioneuronal type form an important recognized subset. Some of the examples for mixed glioneuronal tumors include gangliocytoma, dysembryoplastic neuroepithelial tumor (DNT), ganglioglioma, anaplastic ganglioglioma, and central neurocytoma. The rosette-forming glioneuronal tumor (RGNT) of the fourth ventricle is a new entity that has only slowly emerged in the literature due to its prior classification with other low-grade mixed glial and neuronal tumors. These tumors are relatively infrequent lesions, and therefore, they can be challenging to diagnose for the practicing pathologist. This is a rare biphasic tumor with clearly defined neurocytic and glial components. The tumor is found exclusively in the posterior fossa, where it arises in the midline, usually occupying a substantial fraction of the fourth ventricle, and it is observed by magnetic resonance imaging (MRI) as a circumscribed, solid mass with heterogeneous contrast enhancement. We describe here a case of RGNT occurring in a 22-year-old male. PMID:23361291
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.
Facilitating text reading in posterior cortical atrophy
Rajdev, Kishan; Shakespeare, Timothy J.; Leff, Alexander P.; Crutch, Sebastian J.
2015-01-01
Objective: We report (1) the quantitative investigation of text reading in posterior cortical atrophy (PCA), and (2) the effects of 2 novel software-based reading aids that result in dramatic improvements in the reading ability of patients with PCA. Methods: Reading performance, eye movements, and fixations were assessed in patients with PCA and typical Alzheimer disease and in healthy controls (experiment 1). Two reading aids (single- and double-word) were evaluated based on the notion that reducing the spatial and oculomotor demands of text reading might support reading in PCA (experiment 2). Results: Mean reading accuracy in patients with PCA was significantly worse (57%) compared with both patients with typical Alzheimer disease (98%) and healthy controls (99%); spatial aspects of passages were the primary determinants of text reading ability in PCA. Both aids led to considerable gains in reading accuracy (PCA mean reading accuracy: single-word reading aid = 96%; individual patient improvement range: 6%–270%) and self-rated measures of reading. Data suggest a greater efficiency of fixations and eye movements under the single-word reading aid in patients with PCA. Conclusions: These findings demonstrate how neurologic characterization of a neurodegenerative syndrome (PCA) and detailed cognitive analysis of an important everyday skill (reading) can combine to yield aids capable of supporting important everyday functional abilities. Classification of evidence: This study provides Class III evidence that for patients with PCA, 2 software-based reading aids (single-word and double-word) improve reading accuracy. PMID:26138948
Posterior Reversible Leukoencephalopathy Syndrome Associated with Pazopanib
Foerster, Robert; Welzel, Thomas; Debus, Juergen; Gruellich, Carsten; Jaeger, Dirk; Potthoff, Karin
2013-01-01
A 62-year-old female patient with metastatic renal cell carcinoma under third-line treatment with pazopanib for 8 weeks suddenly developed severe headaches, grand mal seizures and paresis of the left arm in combination with gait instability as well as nausea and vomiting during her vacation abroad. The emergency physician measured systolic blood pressure values over 300 mm Hg and suspected a stroke. The CT imaging without contrast agent in a local hospital did not show any pathologic findings despite bone metastases. The colleagues suspected cerebral metastases or meningeosis carcinomatosa and referred the patient to our department for further diagnostics and treatment planning. An MRI scan ruled out the suspected cerebral metastases or meningeosis carcinomatosa, but showed signs of reversible posterior leukoencephalopathy syndrome (RPLS) in the form of band-like hyperintensities as a sign of cytotoxic edema in the gray and white matter of the left parietal lobe. The patient then reported that similar blood pressure values had been measured shortly after the start of a first-line therapy with sunitinib, so that we discontinued the current treatment with pazopanib. Within 6 days the neurologic symptoms vanished and the patient was discharged. An intermittent hypertension persisted. A follow-up MRI 3 weeks later showed an RPLS-typical cortical infarction in the affected area. RPLS should be considered as the actual reason for neurologic findings in hypertensive patients with known metastatic cancers under tyrosine kinase inhibitor therapy. PMID:23626562
Topical and systemic drug delivery to the posterior segments.
Hughes, Patrick M; Olejnik, Orest; Chang-Lin, Joan-En; Wilson, Clive G
2005-12-13
The posterior segments of the eye are exquisitely protected from the external environment. This poses unique and fairly challenging hurdles for drug delivery. It is somewhat dogmatic that topical ocular delivery is insufficient to achieve therapeutic drug levels in the posterior segments. However, some drugs are currently challenging this dogma. In this review we investigate the constraints and challenges of drug delivery to the posterior segment. Additionally, we outline several potential absorption pathways that may potentially be exploited to deliver drug to the back of the eye. Data on several compounds that achieve therapeutic posterior segment concentrations after topical dosing is presented. Finally, the issues surrounding systemic delivery to the posterior segment are reviewed. PMID:16289435
Isolated posterior capsular rupture following blunt head trauma
Mansour, Ahmad M; Jaroudi, Mahmoud O; Hamam, Rola N; Maalouf, Fadi C
2014-01-01
Closed-globe traumatic cataract is not uncommon in males in the pediatric age group. However, there is a relative paucity of literature on isolated posterior lens capsule rupture associated with closed-globe traumatic cataract. We report a case of a 6-year-old boy who presented with white cataract 1 day after blunt trauma to the forehead associated with posterior capsular rupture that was detected by B-scan ultrasonography preoperatively. No stigmata of trauma outside the posterior capsule could be detected by slit-lamp exam, funduscopy, and optical coherence tomography. Phacoemulsification with posterior chamber intraocular lens implant was performed 24 hours after trauma, with the patient achieving 6/6 visual acuity 1 week and 6 months after surgery. Our case is unique, being the youngest (amblyogenic age) to be reported, with prompt surgical intervention, and with no signs of trauma outside the posterior capsule. PMID:25506201
New techniques for drug delivery to the posterior eye segment.
Eljarrat-Binstock, Esther; Pe'er, Jacob; Domb, Abraham J
2010-04-01
Ocular drug delivery has become an increasingly important field of research especially when treating posterior segment diseases of the eye, such as age-related macular degeneration, diabetic retinopathy, posterior uveitis and retinitis. These diseases are the leading causes of vision loss in developed countries which require repeated long-term administration of therapeutic agents. New drugs for the medication of the posterior ocular segment have emerged, but most drugs are delivered by repeated intravitreal injections associated with ocular complications. Advances in ocular drug delivery system research are expected to provide new tools for the treatment of the posterior segment diseases, providing improved drug penetration, prolonged action, higher efficacy, improved safety and less invasive administration, resulting in higher patient compliance. This review provides an insight into the recent progress and trends in ocular drug delivery systems for treating posterior eye segment diseases, with an emphasis on transscleral iontophoresis. PMID:20155388
Vehicle Localization with Global Probability Density Function for Road Navigation
Chenhao Wang; Zhencheng Hu; Shunsuke Kusuhara; Keiichi Uchimura
2007-01-01
This paper presents a novel approach of real-time vehicle's localization (position and orientation) estimation. Fusion of GPS, gyroscope, speedometer and visual data is employed here to provide real time and accurate localization information. Global probability density function(PDF) is adopted to be the blending factor instead of general Kalman gain, which allows our approach to be robust and accurate for most
Conditional Probability 4.1 Discrete Conditional Probability
California at Santa Cruz, University of
Chapter 4 Conditional Probability 4.1 Discrete Conditional Probability Conditional Probability space and then learn that an event E has occurred. How should we change the probabilities of the remaining events? We shall call the new probability for an event F the conditional probability of F given E
On Transforming Belief Function Models to Probability Models
Cobb, Barry R.; Shenoy, Prakash P.
2003-07-01
(b) > 0. Then, the posterior marginal probability function for A, denoted by P A | b is given by: P A | b (a) = P A,?B (a,?b) / P B (b) (5.1) for all a ? ? A . Now consider the same situation in belief function calculus. Suppose m A, B and Pl A... function or a belief function. The plausibility function Pl corresponding to a bpa m for s is defined as Pl: 2 ? s ? [0,1] such that for all a ? 2 ? s , On Transforming Belief Function Models to Probability Models7 Pl(a) = ?{m(b) | b ? a ? ?}. (2...
Baeta, Miriam; Núñez, Carolina; Cardoso, Sergio; Palencia-Madrid, Leire; Herrasti, Lourdes; Etxeberria, Francisco; de Pancorbo, Marian M
2015-11-01
The Spanish Civil War (1936-1939) and posterior dictatorship (until 1970s) stands as one of the major conflicts in the recent history of Spain. It led to nearly two hundred thousand men and women executed or murdered extra-judicially or after dubious legal procedures. Nowadays, most of them remain unidentified or even buried in irretraceable mass graves across Spain. Here, we present the genetic identification of human remains found in 26 mass graves located in Northern Spain. A total of 252 post-mortem remains were analyzed and compared to 186 relatives, allowing the identification of 87 victims. Overall, a significant success of DNA profiling was reached, since informative profiles (?12 STRs and/or mitochondrial DNA profile) were obtained in 85.71% of the remains. This high performance in DNA profiling from challenging samples demonstrated the efficacy of DNA extraction and amplification methods used herein, given that only around 14.29% of the samples did not provide an informative genetic profile for the analysis performed, probably due to the presence of degraded and/or limited DNA in these remains. However, this study shows a partial identification success rate, which is clearly a consequence of the lack of both appropriate family members for genetic comparisons and accurate information about the victims' location. Hence, further perseverance in the exhumation of other intact graves as well as in the search of more alleged relatives is crucial in order to facilitate and increase the number of genetic identifications. PMID:26378723
Experimental Probability in Elementary School
ERIC Educational Resources Information Center
Andrew, Lane
2009-01-01
Concepts in probability can be more readily understood if students are first exposed to probability via experiment. Performing probability experiments encourages students to develop understandings of probability grounded in real events, as opposed to merely computing answers based on formulae.
Stochastic Computational Models for Accurate Reliability Evaluation of Logic Circuits
Han, Jie
computation, in which probabilities are encoded in the statistics of random binary bit streams. This downscaling makes circuits more susceptible to various factors that lead to manufacturing defects and power are for today. This increasing demand on reliability design calls for accurate evaluation tools
Posterior pituitary dysfunction after traumatic brain injury.
Agha, Amar; Thornton, Evan; O'Kelly, Patrick; Tormey, William; Phillips, Jack; Thompson, Christopher J
2004-12-01
Disorders of water balance are well recognized after traumatic brain injury (TBI), but there are no reliable data on their true prevalence in post-TBI patients. We aimed to evaluate the prevalence of posterior pituitary dysfunction in a large cohort of survivors of TBI. One hundred two consecutive patients (85 males) who suffered severe or moderate TBI were evaluated for diabetes insipidus (DI) at a median of 17 months (range 6-36 months) after the event, using the 8-h water deprivation test (WDT). Their results were compared against normative data obtained from 27 matched, healthy controls. Patients' medical records were retrospectively reviewed for the presence of abnormalities of salt and water balance in the immediate post-TBI period. Twenty-two patients (21.6%) developed DI in the immediate post-TBI period (acute DI group), of whom five had abnormal WDT on later testing. In total, seven patients (6.9%) had abnormal WDT (permanent DI group), five of whom had partial DI. Patients in the acute and permanent DI groups were more likely to have more severe TBI, compared with the rest of the cohort (P < 0.05). In the immediate post-TBI period, 13 patients (12.9%) had syndrome of inappropriate secretion of antidiuretic hormone, which persisted in one patient, and one other patient developed cerebral salt wasting. Diabetes insipidus and syndrome of inappropriate secretion of antidiuretic hormone were common in the immediate post-TBI period. Permanent DI was present in 6.9% of patients who survived severe or moderate TBI, which is higher than traditionally thought. Identification of patients with partial posttraumatic DI is important because appropriate treatment may reduce morbidity and optimize the potential for recovery. PMID:15579748
Subtotal adrenalectomy by the posterior retroperitoneoscopic approach.
Walz, M K; Peitgen, K; Saller, B; Giebler, R M; Lederbogen, S; Nimtz, K; Mann, K; Eigler, F W
1998-06-01
The retroperitoneoscopic approach offers an established operative procedure for primary adrenal gland tumors. It allows a detailed view of the adrenal gland and its surrounding region. Therefore clear differentiation between normal and neoplastic adrenal tissue is sometimes possible, permitting a planned, unilateral, subtotal resection of the gland. Between July 1994 and August 1997 primary benign adrenal gland tumors (11 Conn adenomas, 4 phenochromocytomas, 4 Cushing adenomas, 3 hormonally inactive tumors; 2.4 +/- 1.2 cm in size; 8 on the right, 14 on the left) were removed from 22 patients by the posterior retroperitoneoscopic approach maintaining tumor-free portions of the ipsilateral adrenal gland. Two patients suffered from bilateral pheochromocytomas associated with multiple endocrine neoplasia (MEN-IIa) syndrome and had previously undergone complete adrenalectomy of the contralateral gland. Following subtotal resection the operating time and blood loss did not differ significantly (p > 0.05) from that seen with complete extirpation (46 patients operated during the same period). All patients with Conn adenomas and pheochromocytomas were biochemically and clinically cured (follow-up 11 months; range 1-31 months). The four patients with Cushing adenoma currently require decreasing cortisol substitution. In the two MEN-II patients adrenal gland cortical function could be maintained; one patient is on low-dose steroid supplementation and the other on none. No local recurrence of tumors has been observed. In selected cases the retroperitoneoscopically performed subtotal adrenal gland resection is a safe procedure that can potentially maintain the function of the adrenal gland cortex. PMID:9597938
Posterior cruciate ligament rupture alters in vitro knee kinematics.
Kumagai, Masaru; Mizuno, Yasayuki; Mattessich, Stephen M; Elias, John J; Cosgarea, Andrew J; Chao, Edmund Y
2002-02-01
Isolated posterior cruciate ligament injuries usually are treated nonoperatively, although some patients remain symptomatic, and degenerative changes within the patellofemoral joint and the medial compartment of the tibiofemoral joint have been seen in followup studies. In vitro simulation of knee squatting was done to quantify the influence of the posterior cruciate ligament on tibiofemoral and patellofemoral kinematics. For five knee specimens, knee kinematics were measured before and after sectioning the posterior cruciate ligament, and compared using a Wilcoxon signed rank test. The only kinematic parameters that changed significantly after sectioning the posterior cruciate ligament were the tibial posterior translation and patellar flexion. The posterior translation of the tibia increased significantly between 25 degrees and 90 degrees flexion. The average increase in the posterior translation exceeded 10 mm at 90 degrees flexion. The patellar flexion increased significantly from 30 degrees to 90 degrees flexion. The average patellar flexion increase peaked at 4.4 degrees at 45 degrees flexion. Increased tibial translation could adversely influence joint stability. Increased patellar flexion could increase the patellofemoral joint pressure, especially at the inferior pole, leading to degenerative changes within the patellofemoral joint. PMID:11937888
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.
Rock, Paper, Scissors Probability!
NSDL National Science Digital Library
AMPS GK-12 Program,
Students learn about probability through a LEGO® MINDSTORMS® NTX-based activity that simulates a game of "rock-paper-scissors." The LEGO robot mimics the outcome of random game scenarios in order to help students gain a better understanding of events that follow real-life random phenomenon, such as bridge failures, weather forecasts and automobile accidents. Students learn to connect keywords such as certainty, probable, unlikely and impossibility to real-world engineering applications.
RELATIVIZING CHAITIN'S HALTING PROBABILITY
ROD DOWNEY; DENIS R. HIRSCHFELDT; JOSEPH S. MILLER; ANDR E NIES
As a natural example of a 1-random real, Chaitin proposed the halting probability of a universal prex-free machine. We can relativize this example by considering a universal prex-free oracle machine U. Let A U be the halting probability of U A ; this gives a natural uniform way of producing an A-random real for every A2 2!. It is this
NASA Technical Reports Server (NTRS)
Bollenbacher, Gary; Guptill, James D.
1999-01-01
This report analyzes the probability of a launch vehicle colliding with one of the nearly 10,000 tracked objects orbiting the Earth, given that an object on a near-collision course with the launch vehicle has been identified. Knowledge of the probability of collision throughout the launch window can be used to avoid launching at times when the probability of collision is unacceptably high. The analysis in this report assumes that the positions of the orbiting objects and the launch vehicle can be predicted as a function of time and therefore that any tracked object which comes close to the launch vehicle can be identified. The analysis further assumes that the position uncertainty of the launch vehicle and the approaching space object can be described with position covariance matrices. With these and some additional simplifying assumptions, a closed-form solution is developed using two approaches. The solution shows that the probability of collision is a function of position uncertainties, the size of the two potentially colliding objects, and the nominal separation distance at the point of closest approach. ne impact of the simplifying assumptions on the accuracy of the final result is assessed and the application of the results to the Cassini mission, launched in October 1997, is described. Other factors that affect the probability of collision are also discussed. Finally, the report offers alternative approaches that can be used to evaluate the probability of collision.
Yamazaki, Masashi; Okawa, Akihiko; Fujiyoshi, Takayuki; Furuya, Takeo; Koda, Masao
2010-05-01
We evaluated the clinical results of posterior decompression with instrumented fusion (PDF) for thoracic myelopathy due to ossification of the posterior longitudinal ligament (OPLL). A total of 24 patients underwent PDF, and their surgical outcomes were evaluated by the Japanese Orthopaedic Association (JOA) scores (0-11 points) and by recovery rates calculated at 3, 6, 9 and 12 months after surgery and at a mean final follow-up of 4 years and 5 months. The mean JOA score before surgery was 3.7 points. Although transient paralysis occurred immediately after surgery in one patient (3.8%), all patients showed neurological recovery at the final follow-up with a mean JOA score of 8.0 points and a mean recovery rate of 58.1%. The mean recovery rate at 3, 6, 9 and 12 months after surgery was 36.7, 48.8, 54.0 and 56.8%, respectively. The median time point that the JOA score reached its peak value was 9 months after surgery. No patient chose additional anterior decompression surgery via thoracotomy. The present findings demonstrate that despite persistent anterior impingement of the spinal cord by residual OPLL, PDF can result in considerable neurological recovery with a low risk of postoperative paralysis. Since neurological recovery progresses slowly after PDF, we suggest that additional anterior decompression surgery is not desirable during the early stage of recovery. PMID:20049486
Bayesian Retrieval of Complete Posterior PDFs of Oceanic Rain Rate From Microwave Observations
NASA Technical Reports Server (NTRS)
Chiu, J. Christine; Petty, Grant W.
2005-01-01
This paper presents a new Bayesian algorithm for retrieving surface rain rate from Tropical Rainfall Measurements Mission (TRMM) Microwave Imager (TMI) over the ocean, along with validations against estimates from the TRMM Precipitation Radar (PR). The Bayesian approach offers a rigorous basis for optimally combining multichannel observations with prior knowledge. While other rain rate algorithms have been published that are based at least partly on Bayesian reasoning, this is believed to be the first self-contained algorithm that fully exploits Bayes Theorem to yield not just a single rain rate, but rather a continuous posterior probability distribution of rain rate. To advance our understanding of theoretical benefits of the Bayesian approach, we have conducted sensitivity analyses based on two synthetic datasets for which the true conditional and prior distribution are known. Results demonstrate that even when the prior and conditional likelihoods are specified perfectly, biased retrievals may occur at high rain rates. This bias is not the result of a defect of the Bayesian formalism but rather represents the expected outcome when the physical constraint imposed by the radiometric observations is weak, due to saturation effects. It is also suggested that the choice of the estimators and the prior information are both crucial to the retrieval. In addition, the performance of our Bayesian algorithm is found to be comparable to that of other benchmark algorithms in real-world applications, while having the additional advantage of providing a complete continuous posterior probability distribution of surface rain rate.
Magnetic source imaging in posterior cortex epilepsies.
Badier, Jean-Michel; Bartolomei, Fabrice; Chauvel, Patrick; Bénar, Christian-George; Gavaret, Martine
2015-01-01
Posterior cortex epilepsies (PCE) are characterized by less satisfying postoperative results than temporal lobe epilepsies and are thus challenging for non-invasive presurgical investigations. The objective of this study was to evaluate the performance of magnetic source imaging (MSI) in PCE, validating the results by the SEEG (stereoelectroencephalography) definition of irritative and epileptogenic zones (IZ and EZ). Fourteen PCE surgery candidates were investigated using MSI and SEEG. LCMV (Linearly Constrained Minimum Variance) and MUSIC algorithms were used. IZ was quantified using a semi-automatic detection of interictal spikes. EZ was quantified using the epileptogenicity index (EI) method that accounts for both the propensity of a brain area to generate rapid discharges and the time for this area to get involved in the seizure. EI values range from 0 (no epileptogenicity) to 1 (maximal epileptogenicity). Levels of concordance between MSI and IZ, MSI and EZ were determined as follows: A = localized on MSI and SEEG for the site of value 1 (IZ and EZ quantification), B = localized on MSI and SEEG for a part of the IZ or a structure involved in the EZ (without the maximal value 1), C = localized on MSI and not SEEG, D = localized on SEEG and not MSI, E = localized on MSI and SEEG, discordant for site. Five PCE cases were characterized by focal IZ, nine by distributed IZ between several distant brain areas. MSI allowed to determinate IZ in 4/5 focal IZ cases. In case of distributed IZ, levels of concordance were A (2 cases), B (4 cases) and D (3 cases). In most distributed cases, MSI allowed to localize only a part of the IZ. Medial temporal involvement in the IZ was frequent (9/12 cases) and not evidenced by MSI. The brain area that demonstrated the maximal value of EI was shown by MSI in four out of five (80 %) focal IZ cases, in two out of nine (22 %) distributed cases. MSI results depend on IZ characteristics. A distributed IZ organization presents difficulties for MSI and highlights the need for further methodological approaches. PMID:25352165
21 CFR 872.3900 - Posterior artificial tooth with a metal insert.
Code of Federal Regulations, 2013 CFR
2013-04-01
...false Posterior artificial tooth with a metal insert. 872.3900 Section 872...3900 Posterior artificial tooth with a metal insert. (a) Identification. A posterior artificial tooth with a metal insert is a porcelain device with...
21 CFR 872.3900 - Posterior artificial tooth with a metal insert.
Code of Federal Regulations, 2012 CFR
2012-04-01
...false Posterior artificial tooth with a metal insert. 872.3900 Section 872...3900 Posterior artificial tooth with a metal insert. (a) Identification. A posterior artificial tooth with a metal insert is a porcelain device with...
21 CFR 886.4392 - Nd:YAG laser for posterior capsulotomy and peripheral iridotomy.
Code of Federal Regulations, 2011 CFR
2011-04-01
...false Nd:YAG laser for posterior...peripheral iridotomy. 886.4392...4392 Nd:YAG laser for posterior...peripheral iridotomy. (a) Identification... The Nd:YAG laser for posterior...peripheral iridotomy consists...
21 CFR 886.4392 - Nd:YAG laser for posterior capsulotomy and peripheral iridotomy.
Code of Federal Regulations, 2014 CFR
2014-04-01
...false Nd:YAG laser for posterior...peripheral iridotomy. 886.4392...4392 Nd:YAG laser for posterior...peripheral iridotomy. (a) Identification... The Nd:YAG laser for posterior...peripheral iridotomy consists...
21 CFR 886.4392 - Nd:YAG laser for posterior capsulotomy and peripheral iridotomy.
Code of Federal Regulations, 2013 CFR
2013-04-01
...false Nd:YAG laser for posterior...peripheral iridotomy. 886.4392...4392 Nd:YAG laser for posterior...peripheral iridotomy. (a) Identification... The Nd:YAG laser for posterior...peripheral iridotomy consists...
21 CFR 886.4392 - Nd:YAG laser for posterior capsulotomy and peripheral iridotomy.
Code of Federal Regulations, 2012 CFR
2012-04-01
...false Nd:YAG laser for posterior...peripheral iridotomy. 886.4392...4392 Nd:YAG laser for posterior...peripheral iridotomy. (a) Identification... The Nd:YAG laser for posterior...peripheral iridotomy consists...
53Probability, Verbal Expressions of Marginal Probability of Discrete Variables
Druzdzel, Marek J.
53Probability, Verbal Expressions of Marginal Probability of Discrete Variables From the joint probability of several variables, we can obtain the marginal probability for a subset of them by summing over over the variable we want to "eliminate," namely, Y: In the same way, the marginal probability P
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 Large Numbers and the Central Limit Theorem N 27/28 27: Conditional probability (continued) 28: Bayes
Anterior-Posterior Cerebral Blood Volume Gradient in Human Subiculum
Talati, Pratik; Rane, Swati; Kose, Samet; Gore, John; Heckers, Stephan
2014-01-01
The human hippocampal formation is characterized by anterior-posterior gradients of cell density, neurochemistry and hemodynamics. In addition, some functions are associated with specific subfields (subiculum, CA1–4, dentate gyrus) and regions (anterior and posterior). We performed contrast-enhanced, high-resolution T1-weighted 3T steady state (SS) imaging to investigate cerebral blood volume (CBV) gradients of the hippocampal formation. We studied 14 healthy subjects and found significant CBV gradients (anterior > posterior) in the subiculum but not in other hippocampal subfields. Since CBV is a marker of basal metabolism, these results indicate a greater baseline activity in the anterior compared to the posterior subiculum. This gradient might be related to the role of the subiculum as the main outflow station of the hippocampal formation and might have implications for the mechanisms of neuropsychiatric disorders. PMID:24677295
The role of wnt8 in posterior mesoderm formation
Kelton, Cathryn Renee
2009-05-15
source of secreted Bmp antagonists that regulate Bmp-dependent ventral and posterior mesoderm patterning. Because the organizer impacts Bmp signaling activity, it is not clear whether functions attributed to zygotic Wnt signaling are in fact indirectly...
Posterior corneal curvature changes after myopic laser in situ keratomileusis
Berthold Seitz; Francia Torres; Achim Langenbucher; Ashley Behrens; Enrique Suárez
2001-01-01
ObjectiveTo assess the posterior corneal power and asphericity changes after myopic laser in situ keratomileusis (LASIK) and to correlate these changes with the amount of correction and the residual stromal bed thickness.
NSDL National Science Digital Library
Stark, Philip B.
This applet lets you highlight the set A, the set B, the set C, the universal set S, the empty set {}, the complement of A (Ac), the complement of B (Bc), the complement of C (Cc), the intersection of A and B (AB), the union of A and B (A or B), the intersection of the complement of A with B (AcB), the intersection of A with the complement of B (ABc), the intersection of A, B, and C (ABC), the union of A, B, and C (A or B or C), the intersection of Ac and B and C (AcBC), and the union of the complement of A and the intersection of B and C (Ac or BC). One can think of the relative area of a set to the area of S as a probability. You can drag the events A, B, and C around, which changes the probability of their intersection and of their union. This applet displays six conditional probabilities: P(A|B), P(Ac|B), P(B|A), P(A|BC), P(Ac|BC), and P(A|(B or C)). When the corresponding checkbox is ticked, the events whose probabilities are involved in computing the conditional probability are highlighted in contrasting colors.
Abnormalities of fixation, saccade and pursuit in posterior cortical atrophy
Kaski, Diego; Yong, Keir X. X.; Paterson, Ross W.; Slattery, Catherine F.; Ryan, Natalie S.; Schott, Jonathan M.; Crutch, Sebastian J.
2015-01-01
The clinico-neuroradiological syndrome posterior cortical atrophy is the cardinal ‘visual dementia’ and most common atypical 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
Neurobehavioral alterations in an adolescent following posterior fossa tumor resection
Hanne Baillieux; Hyo Jung De Smet; Geoffrey Lesage; Philippe Paquier; Peter P. De Deyn; Peter Mariën
2006-01-01
The posterior fossa syndrome (PFS) consists of a variety of symptoms, including cerebellar mutism, behavioral disturbances\\u000a and personality changes. We report longitudinal clinical, neuroradiological and neurobehavioral findings in a 19-year-old\\u000a left-handed patient, diagnosed with attentional deficit hyperactivity disorder (ADHD) at the age of 12, who underwent posterior\\u000a fossa tumor resection. Although the patient did not develop cerebellar mutism after surgery,
Posterior sagittal approach for resection of sacrococcygeal teratomas
Iftikhar Ahmad Jan; Ejaz A. Khan; Nuzhat Yasmeen; Hazratullah Orakzai; Jahria Saeed
2011-01-01
The aim is to evaluate the ease of access, surgical trauma and cosmetic results of posterior sagittal approach for sacrococygeal\\u000a teratomas (SCTs). From January 2002 to June 2010, we operated 19 cases of SCT exclusively through posterior sagittal approach.\\u000a Patients were placed in knee chest position. An elliptical incision was made for the excision of the tumor. Care was taken
Posterior sagittal anorectoplasty for adults. A sphincter-saving operation.
Jorge, E; Ballantine, T V; Joehl, R J
1987-09-01
We performed posterior sagittal anorectoplasty to treat two adult patients. One patient had an idiopathic stricture extending from the proximal sigmoid colon to the anus. The second patient was born with a high imperforate anus and, following a pull-through procedure as an infant, remained totally incontinent of feces. Both patients now have excellent fecal continence following this operation. The posterior sagittal anorectoplasty may be used to preserve rectal continence in selected adults. PMID:3619628
Prosthetic left renocaval bypass for posterior nutcracker syndrome.
Zhang, Xuepei; Wang, Shengzheng; Wei, Jinxing
2015-04-01
A 58-year-old man presented with severe hematuria of unknown origin and intermittent left flank pain for 8 months, and he was diagnosed with posterior nutcracker syndrome. He underwent prosthetic left renocaval bypass with complete resolution of symptoms. Computed tomography showed a functional graft between the left renal vein and caval vein. This technique is a feasible choice for surgical treatment of posterior nutcracker syndrome with satisfactory results. PMID:25972662
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
Accurate direct illumination using iterative adaptive sampling.
Donikian, Michael; Walter, Bruce; Bala, Kavita; Fernandez, Sebastian; Greenberg, Donald P
2006-01-01
This paper introduces a new multipass algorithm for efficiently computing direct illumination in scenes with many lights and complex occlusion. Images are first divided into 8 x 8 pixel blocks and for each point to be shaded within a block, a probability density function (PDF) is constructed over the lights and sampled to estimate illumination using a small number of shadow rays. Information from these samples is then aggregated at both the pixel and block level and used to optimize the PDFs for the next pass. Over multiple passes the PDFs and pixel estimates are updated until convergence. Using aggregation and feedback progressively improves the sampling and automatically exploits both visibility and spatial coherence. We also use novel extensions for efficient antialiasing. Our adaptive multipass approach computes accurate direct illumination eight times faster than prior approaches in tests on several complex scenes. PMID:16640249
NASA Astrophysics Data System (ADS)
Voiculescu, Dan
2006-03-01
Free probability theory provides a probabilistic framework for quantities with the highest degree of noncommutativity. This brings out the ties among von Neumann algebras of free groups, the large N limit of random multimatrix models, the operators of the Boltzmann Fock space and combinatorics of noncrossing partitions. Many concepts of classical probability theory have free probability counterparts. In particular, the free analogues of entropy and of Fisher's information will be one of the main focuses of the talk. The analysis of the free variables involved, relies on free difference quotient derivations, which give rise to bialgebras in the class with derivation comultiplication, which appears to be selfdual. Duality for such bialgebras underlies the free entropy and analytic aspects of the free Markov property.
Acceptance, values, and probability.
Steel, Daniel
2015-10-01
This essay makes a case for regarding personal probabilities used in Bayesian analyses of confirmation as objects of acceptance and rejection. That in turn entails that personal probabilities are subject to the argument from inductive risk, which aims to show non-epistemic values can legitimately influence scientific decisions about which hypotheses to accept. In a Bayesian context, the argument from inductive risk suggests that value judgments can influence decisions about which probability models to accept for likelihoods and priors. As a consequence, if the argument from inductive risk is sound, then non-epistemic values can affect not only the level of evidence deemed necessary to accept a hypothesis but also degrees of confirmation themselves. PMID:26386533
Optimizing tooth form with direct posterior composite restorations
Raghu, Ramya; Srinivasan, Raghu
2011-01-01
Advances in material sciences and technology have provided today's clinicians the strategies to transform the mechanistic approach of operative dentistry into a biologic philosophy. In the last three decades, composite resins have gone from being just an esthetically pleasing way of restoring Class III and Class IV cavities to become the universal material for both anterior and posterior situations as they closely mimic the natural esthetics while restoring the form of the human dentition. In order to enhance their success, clinicians have to rethink their protocol instead of applying the same restorative concepts and principles practiced with metallic restorations. Paralleling the evolution of posterior composite resin materials, cavity designs, restorative techniques and armamentarium have also developed rapidly to successfully employ composite resins in Class II situations. Most of the earlier problems with posterior composites such as poor wear resistance, polymerization shrinkage, postoperative sensitivity, predictable bonding to dentin, etc., have been overcome to a major extent. However, the clinically relevant aspect of achieving tight contacts in Class II situations has challenged clinicians the most. This paper reviews the evolution of techniques and recent developments in achieving predictable contacts with posterior composites. A Medline search was performed for articles on “direct posterior composite contacts.” The keywords used were “contacts and contours of posterior composites.” The reference list of each article was manually checked for additional articles of relevance. PMID:22144797
Parametric Probability Distributions
NSDL National Science Digital Library
Myers, Lawrence.
2000-01-01
The Environmental Protection Agency (EPA) has released a series of Parametric Probability Distributions to be used in conjunction with the previously released Exposure Factors Handbook. Whereas the Exposure Factors Handbook provides summaries of available statistical data on several factors used in assessing human exposure to toxic chemicals, the Parametric Probability Distributions document summarizes procedures to fit distributions to some of those data. Three factors (tap water intake, population mobility, and inhalation rules) are considered as test cases in the models, and recommendations are made for models that provide the best fit. For students of statistics, these documents could be used as supplemental examples, illustrating methods useful for addressing actual statistical challenges.
NSDL National Science Digital Library
K-12 Outreach,
Education in a free society must prepare citizens to make informed choices in all areas of their lives. They must be able to grasp the information being presented, analyze it, and make reasoned decisions. To accomplish these goals, students learn to collect, organize, and display relevant data to answer questions that can be addressed with data; use appropriate statistical methods and predictions that are based on data; develop and evaluate inferences and predictions that are based on data; and apply basic concepts of probability. Probability is the study of chance and the possibility that an event will occur.
Probability Rehearsal Renato Lo Cigno
Lo Cigno, Renato Antonio
Probability Rehearsal Renato Lo Cigno Simulation and Performance Evaluation 2014-15 Probability Rehearsal - Renato Lo Cigno 1 #12;Why Probabilities & Uncertainty In models we reduce a complex physical-based delay measure Probability Rehearsal - Renato Lo Cigno - Probability basics 2 #12;Sample Space & Events
D'Ambrosi, Riccardo; Perfetti, Carlo; Garavaglia, Guido; Taverna, Ettore
2015-01-01
This case presents the challenges of the surgical management for a patient with a history of recurrent posterior shoulder instability and subsequently traumatic anterior dislocation. The patient was already on the waiting list for an arthroscopic posterior stabilization with anchors, when a car accident caused an additional anterior shoulder dislocation. This traumatic anterior dislocation created a bone loss with a glenoid fracture and aggravated the preexisting posterior instability. In order to address both problems, we decided to perform an arthroscopically assisted Latarjet procedure for anterior instability and to stabilize with a bone graft for posterior instability. To our best knowledge, this type of surgical procedure has so far never been reported in the literature. The purpose of this report is to present the surgical technique and to outline the decision making process. PMID:26288539
D’Ambrosi, Riccardo; Perfetti, Carlo; Garavaglia, Guido; Taverna, Ettore
2015-01-01
This case presents the challenges of the surgical management for a patient with a history of recurrent posterior shoulder instability and subsequently traumatic anterior dislocation. The patient was already on the waiting list for an arthroscopic posterior stabilization with anchors, when a car accident caused an additional anterior shoulder dislocation. This traumatic anterior dislocation created a bone loss with a glenoid fracture and aggravated the preexisting posterior instability. In order to address both problems, we decided to perform an arthroscopically assisted Latarjet procedure for anterior instability and to stabilize with a bone graft for posterior instability. To our best knowledge, this type of surgical procedure has so far never been reported in the literature. The purpose of this report is to present the surgical technique and to outline the decision making process.
Khosla, Sid; Murugappan, Shanmugam; Lakhamraju, Raghavaraju; Gutmark, Ephraim
2008-01-01
Objectives To quantify the anterior-posterior velocity gradient, we studied the velocity flow fields above the vocal folds in both the midcoronal and midsagittal planes. It was also our purpose to use these fields to deduce the mechanisms that cause the anterior-posterior gradient and to determine whether the vortical structures are highly 3-dimensional. Methods Using the particle imaging velocimetry method for 5 excised canine larynges. we obtained phase-averaged velocity fields in the midcoronal and midsagittal planes for 30 phases of phonation. The velocity fields were determined synchronously with the vocal fold motion recorded by high-speed videography. Results The results show that immediately above the folds, there is no significant anterior-posterior velocity gradient. However, as the flow travels downstream, the laryngeal jet tends to narrow in width and skew toward the anterior commissure. Vortices are seen at the anterior and posterior edges of the flow. Conclusions The downstream narrowing in the midsagittal plane is consistent with and is probably due to a phenomenon known as axis switching. Axis switching also involves vortices in the sagittal and coronal planes bending in the axial plane. This results in highly 3-dimensional, complex vortical structures. However, there is remarkable cyclic repeatability of these vortices during a phonation cycle. PMID:18357838
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
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.
Algorithmic Probability From Scholarpedia
Hutter, Marcus
. Bayes, Occam and Epicurus In an inductive inference problem there is some observed data and a set rests upon two philosophical principles. The first is Epicurus' (342? B.C. - 270 B.C.) From Scholarpedia. Contents 1 Bayes, Occam and Epicurus 2 Discrete Universal A Priori Probability 3 Continuous Universal
Approximating Integrals Using Probability
ERIC Educational Resources Information Center
Maruszewski, Richard F., Jr.; Caudle, Kyle A.
2005-01-01
As part of a discussion on Monte Carlo methods, which outlines how to use probability expectations to approximate the value of a definite integral. The purpose of this paper is to elaborate on this technique and then to show several examples using visual basic as a programming tool. It is an interesting method because it combines two branches of…
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.
Probability: A Project Approach
NSDL National Science Digital Library
Levine, Maita
This article, created by Maita Levine and Raymond H. Rolwing of the University of Cincinnati, describes an assignment given in various introductory statistics courses and the experience of probability and statistics in the classroom. There are five different examples given in this lesson. Additionally, there are external references for those interesting in examining this topic at a more in-depth level.
A Unifying Probability Example.
ERIC Educational Resources Information Center
Maruszewski, Richard F., Jr.
2002-01-01
Presents an example from probability and statistics that ties together several topics including the mean and variance of a discrete random variable, the binomial distribution and its particular mean and variance, the sum of independent random variables, the mean and variance of the sum, and the central limit theorem. Uses Excel to illustrate these…
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…
Probability and Cancer Clusters
ERIC Educational Resources Information Center
Hamilton-Keene, Rachael; Lenard, Christoper T.; Mills, Terry M.
2009-01-01
Recently there have been several news items about possible cancer clusters in the Australian media. The term "cancer cluster" is used when an unusually large number of people in one geographic area, often a workplace, are diagnosed with cancer in a short space of time. In this paper the authors explore this important health issue using probability…
Hasankhani, Ebrahim Ghayem; Ebrahimzadeh, Mohamed Hosein; Kachooei, Amir Reza; Heidari, Hosein
2013-01-01
Study Design Retrospective study. Purpose To determine if posterior surgery alone can satisfactorily treat post-traumatic kyphosis (PTK). Overview of Literature One of the worst complications of vertebral fractures is PTK. The type of surgery and approach to treat a symptomatic and refractory PTK is a challenging issue in spinal surgery, and yet, there is no specific treatment algorithm. Methods From August 2003 to September 2010, we collected 26 cases (male to female ratio, 2.25; mean age, 31.9±9.7 years and follow-up period of 42.4±8.1 months) with PTK treated by posterior column osteotomy, spondylodesis, instrumentation and cement vertebroplasty in one stage posterior surgery. PTK angle, Oswestry Disability Index (ODI), visual analogue scale (VAS), and subjective satisfaction from surgery were used to determine the results. We used a student t test for analyzing the data before and after surgery. Results In our patients, T11 and L1 had the highest incidence of vertebral fractures. The results indicated that in PTK, ODI, and VAS were significantly improved this surgery. Solid fusion occurred in 96.2% of patients with 3.2°±2.1° loss of correction. A total of 84.6% of patients have satisfaction level of excellent and good. Conclusions Posterior surgery alone with posterior column osteotomy, vertebroplasty, posterior spinal fusion and instrumentation can effectively treat symptomatic PTK. PMID:24353841
Posterior transodontoid fixation: A new fixation (Kotil) technique.
Kotil, Kad?r; Köksal, Neslihan Sütpideler; Kayac?, Selim
2011-01-01
Anterior odontoid screw fixation or posterior C1-2 fusion techniques are routinely used in the treatment of Type II odontoid fractures, but these techniques may be inadequate in some types of odontoid fractures. In this new technique (Kotil technique), through a posterior bilateral approach, transarticular screw fixation was performed at the non-dominant vertebral artery (VA) side and posterior transodontoid fixation technique was performed at the dominant VA side. C1-2 complex fusion was aimed with unilateral transarticular fixation and odontoid fixation with posterior transodontoid screw fixation. Cervical spinal computed tomography (CT) of a 40-year-old male patient involved in a motor vehicle accident revealed an anteriorly dislocated Type II oblique dens fracture, not reducible by closed traction. Before the operation, the patient was found to have a dominant right VA with Doppler ultrasound. He was operated through a posterior approach. At first, transarticular screw fixation was performed at the non-dominant (left) side, and then fixation of the odontoid fracture was achieved by directing the contralateral screw (supplemental screw) medially and toward the apex. Cancellous autograft was scattered for fusion without the need for structural bone graft or wiring. Postoperative cervical spinal CT of the patient revealed that stabilization was maintained with transarticular screw fixation and reduction and fixation of the odontoid process was achieved completely by posterior transodontoid screw fixation. The patient is at the sixth month of follow-up and complete fusion has developed. With this new surgical technique, C1-2 fusion is maintained with transarticular screw fixation and odontoid process is fixed by concomitant contralateral posterior transodontoid screw (supplemental screw) fixation; thus, this technique both stabilizes the C1-2 complex and fixes the odontoid process and the corpus in atypical odontoid fractures, appearing as an alternative new technique among the previously defined C1-C2 fixation techniques in eligible cases. PMID:22013375
[Postoperative opacification of posterior chamber intraocular lenses - a review].
Schmidbauer, J M; Werner, L; Apple, D J; Pandey, S K; Izak, A M; Trivedi, R H; Macky, T A; Auffarth, G U; Peng, Q; Arthur, S N; Escobar-Gomez, M; Ma, L; Vargas, L G
2001-09-01
Postoperative opacification of intraocular lenses (IOLs) is a very unpleasant complication for the ophthalmic surgeon and the patient. We report on our experiences with opacification of different foldable IOL designs and rigid poly (methyl methacrylate) (PMMA) posterior chamber lenses.1. Snowflake degeneration of PMMA IOLs: This condition is an unanticipated and surprising late postoperative finding 8 to 15 years after implantation. In our opinion, this complication is probably not related to the PMMA biomaterial itself, but rather it appears to represent a manufacturing problem that has affected a selected, albeit large number of lenses manufactured in the 1980s-mid 1990s.2. Degeneration of UV absorber material and calcium deposits within the optic of hydrophilic IOLs: Two years postoperatively degenerations of UV absorber material and calcium deposits within the optic of single piece hydrophilic acrylic lenses SC60B-OUV manufactured by MDR (Medical developmental research Inc. Clearwater FL, USA) can occur. Although the precise mechanism is not fully known, it was assumed that these opacifications are due to premature aging of the UV blocking agent incorporated in the lens biomaterial and calcification.3. Calcification on the surface of the Bausch & Lomb Hydroviewtrade mark IOLs: Twelve to 15 months postoperatively granular surface calcifications in Hydroviewtrade mark IOLs occured. The mechanism is not fully understood. According to Bausch and Lomb studies, part of the components of the packaging contained silicone, which may have come off the packaging onto the lens optic, where it then appears to be a catalyst for calcium precipitation. The manufacturer has correlated a change in packaging with the appearance of the opacification. The manufacturer now believes that this problem has been solved. However, final verification will require a careful 1 - 2 years clinical study.4. Glistenings in the hydrophobic acrylic AcrySoftrade mark IOLs: The time frame of glistenings in the AcrySoftrade mark IOLs is highly variable. It has been suggested that the occurrence of glistenings may be related to variations in the temperature of the lens just prior to and or during insertion into the eye. Formation of vacuoles may occur within the submersed acrylic polymer when there is a transient increase and then decrease in temperature during the surgical procedure. "Glistenings" may then subsequently form by ingress of anterior chamber fluid. Contrast sensitivity can been decreased in some patients, but clinically significant decrease of visual acuity has been rare. PMID:11590465
SYSTEMS BIOLOGY Accurate information transmission
Tsimring, Lev S.
SYSTEMS BIOLOGY Accurate information transmission through dynamic biochemical signaling networks) and variability in cellular states (extrinsic noise) degrade information transmitted through signaling networks-induced information loss. In the extracellular signalregulated kinase (ERK), calcium (Ca2+ ), and nuclear factor
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
Probability and Geometry (elementary)
NSDL National Science Digital Library
1994-01-01
This lesson plan provides students with an opportunity to explore and determine what makes a game fair. Students use spinners with a variety of sector sizes in order to predict which outcome is more likely and then explain their reasoning. Students also experiment with each spinner to see if their predictions are accurate. The lesson utilizes java applets for a spinner and an adjustable spinner, and also includes a PDF of exploration questions.
An accurate iris location method for low quality iris images
NASA Astrophysics Data System (ADS)
Wang, Ning; Li, Qiong; Abd El-Latif, Ahmed A.; Zhang, Tiejun; Peng, Jialiang
2012-04-01
Iris location plays an important role in iris recognition system. Traditional iris location methods based on canny operator and integro-differential operator are affected by reflections, illumination inconsistency and eyelash. In this paper, we introduce an accurate iris location method for low quality iris images. First, a reflection removal method is used to interpolate the specular reflection. Then, we utilize Probable boundary (Pb) edge detection operator to detect papillary boundary with a lower interference point. Moreover, we optimize the Hough transform to obtain high accuracy result. Experimental results demonstrate that the location results of the proposed method are more accurate than other methods.
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.
Continuous Probability 2.1 Simulation of Continuous Probabilities
California at Santa Cruz, University of
Chapter 2 Continuous Probability Densities 2.1 Simulation of Continuous Probabilities of possible outcomes. Probabilities Example 2.1 We begin by constructing a spinner, which consists of a circle the interval [0, 1). We would like to construct a probability model in which each outcome is equally likely
The Probability Calculus 1 0 . THE PROBABILITY OPERATOR
Fitelson, Branden
Chapter 10 The Probability Calculus 1 0 . THE PROBABILITY OPERATOR Chapter 3 illustrates how truth something analogous for inductive reasoning: a procedure that would enable us to calculate probabilities of complex statements from the probabilities of simpler ones and thereby to determine the inductive
Intro Probability Rabbits Description Predictions Ontology of Earthquake Probability: Metaphor
Stark, Philip B.
Intro Probability Rabbits Description Predictions Ontology of Earthquake Probability: Metaphor, Earthquake Clustering and Patterns in Fault Networks 2013 Program on Mathematics of Planet Earth SAMSI are earthquake probabilities? Where does earthquake probability come from? What does "the chance of an earthquake
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.
Waste Package Misload Probability
J.K. Knudsen
2001-11-20
The objective of this calculation is to calculate the probability of occurrence for fuel assembly (FA) misloads (i.e., Fa placed in the wrong location) and FA damage during FA movements. The scope of this calculation is provided by the information obtained from the Framatome ANP 2001a report. The first step in this calculation is to categorize each fuel-handling events that occurred at nuclear power plants. The different categories are based on FAs being damaged or misloaded. The next step is to determine the total number of FAs involved in the event. Using the information, a probability of occurrence will be calculated for FA misload and FA damage events. This calculation is an expansion of preliminary work performed by Framatome ANP 2001a.
Cardiorespiratory fitness in survivors of pediatric posterior fossa tumor.
Wolfe, Kelly R; Hunter, Gary R; Madan-Swain, Avi; Reddy, Alyssa T; Baños, James; Kana, Rajesh K
2012-08-01
Advances in medical therapies have greatly improved survivorship rates in children diagnosed with brain tumor; as a result, morbidities associated with survivorship have become increasingly important to identify and address. In general, pediatric posterior fossa tumor survivors tend to be less physically active than peers. This may be related to late effects of diagnosis and treatment, including cardiovascular, endocrine, psychological, and neurocognitive difficulties. Exercise has been shown to be effective in improving physical functioning, mood, and even cognitive functioning. Consequently, the benefits of physical exercise need to be explored and incorporated into the daily lives of pediatric posterior fossa tumor survivors. The primary aim of the present study was to establish the feasibility and safety of cardiorespiratory fitness testing in pediatric posterior fossa tumor survivors who had received cranial radiation therapy. In addition, comparing our cohort with previously published data, we found that pediatric posterior fossa tumor survivors tended to be less fit than children with pulmonary disease and healthy controls and approximately as fit as children with chronic heart disease and survivors of other types of childhood cancer. The importance of cardiorespiratory fitness in pediatric posterior fossa tumor survivors is discussed along with implications for future directions. PMID:22810754
Drug delivery to the posterior segment of the eye.
Thrimawithana, Thilini Rasika; Young, Simon; Bunt, Craig Robert; Green, Colin; Alany, Raid Ghassan
2011-03-01
Delivery of drugs to the posterior eye is challenging, owing to anatomical and physiological constrains of the eye. There is an increasing need for managing rapidly progressing posterior eye diseases, such as age-related macular degeneration, diabetic retinopathy and retinitis pigmentosa. Drug delivery to the posterior segment of the eye is therefore compounded by the increasing number of new therapeutic entities (e.g. oligonucleotides, aptamers and antibodies) and the need for chronic therapy. Currently, the intravitreal route is widely used to deliver therapeutic entities to the retina. However, frequent administration of drugs via this route can lead to retinal detachment, endophthalmitis and increased intraocular pressure. Various controlled delivery systems, such as biodegradable and non-biodegradable implants, liposomes and nanoparticles, have been developed to overcome such adverse effects, with some success. The periocular route is a promising alternative, owing to the large surface area and the relatively high permeability of the sclera. Yet, the blood-retinal barrier and efflux transporters hamper the transport of therapeutic entities to the retina. As such, the efficient delivery of drugs to the posterior eye remains a major challenge facing the pharmaceutical scientist. In this review, we discuss the barriers of the posterior eye drug delivery and the various drug-delivery strategies used to overcome these barriers. PMID:21167306
Cardiorespiratory Fitness in Survivors of Pediatric Posterior Fossa Tumor
Wolfe, Kelly R.; Hunter, Gary R.; Madan-Swain, Avi; Reddy, Alyssa T.; Baños, James; Kana, Rajesh K.
2012-01-01
Advances in medical therapies have greatly improved survivorship rates in children diagnosed with brain tumor; as a result, morbidities associated with survivorship have become increasingly important to identify and address. In general, pediatric posterior fossa tumor survivors tend to be less physically active than peers. This may be related to late effects of diagnosis and treatment, including cardiovascular, endocrine, psychological, and neurocognitive difficulties. Exercise has been shown to be effective in improving physical functioning, mood, and even cognitive functioning. Consequently, the benefits of physical exercise need to be explored and incorporated into the daily lives of pediatric posterior fossa tumor survivors. The primary aim of the present study was to establish the feasibility and safety of cardiorespiratory fitness testing in pediatric posterior fossa tumor survivors who had received cranial radiation therapy. Additionally, comparing our cohort to previously published data, we found that pediatric posterior fossa tumor survivors tended to be less fit than children with pulmonary disease as well as healthy controls, and approximately as fit as children with chronic heart disease and survivors of other types of childhood cancer. The importance of cardiorespiratory fitness in pediatric posterior fossa tumor survivors is discussed along with implications for future directions. PMID:22810754
Okamoto, Shigetoshi; Mizu-Uchi, Hideki; Okazaki, Ken; Hamai, Satoshi; Nakahara, Hiroyuki; Iwamoto, Yukihide
2015-08-01
We used a musculoskeletal model validated with in vivo data to evaluate the effect of tibial posterior slope on knee kinematics, quadriceps force, and patellofemoral contact force after posterior-stabilized total knee arthroplasty. The maximum quadriceps force and patellofemoral contact force decreased with increasing posterior slope. Anterior sliding of the tibial component and anterior impingement of the anterior aspect of the tibial post were observed with tibial posterior slopes of at least 5° and 10°, respectively. Increased tibial posterior slope contributes to improved exercise efficiency during knee extension, however excessive tibial posterior slope should be avoided to prevent knee instability. Based on our computer simulation we recommend tibial posterior slopes of less than 5° in posterior-stabilized total knee arthroplasty. PMID:25791671
Endothelin: A novel peptide in the posterior pituitary system
Yoshizawa, Toshihiro; Kanazawa, Ichiro; Shinmi, Osamu; Kimura, Sadao; Yanagisawa, Masashi; Masaki, Tomoh; Uchiyama, Yasuo (Univ. of Tsukuba (Japan)); Giaid, A.; Gibson, S.J.; Polak, J.M. (Royal Postgraduate Medical School, London (England))
1990-01-26
Endothelin (ET), originally characterized as a 21-residue vasoconstrictor peptide from endothelial cells, is present in the porcine spinal cord and may act as a neuropeptide. Endothelin-like immunoreactivity has now been demonstrated by immunohistochemistry in the paraventricular and supraoptic nuclear neurons and their terminals in the posterior pituitary of the pig and the rat. The presence of ET in the porcine hypothalamus was confirmed by reversed-phase high-pressure liquid chromatography and radioimmunoassay. Moreover, in situ hybridization demonstrated ET messenger RNA in porcine paraventricular nuclear neurons. Endothelin-like immunoreactive products in the posterior pituitary of the rat were depleted by water deprivation, suggesting a release of ET under physiological conditions. These findings indicate that ET is synthesized in the posterior pituitary system and may be involved in neurosecretory functions.
Subjective experience, involuntary movement, and posterior alien hand syndrome
Bundick, T; Spinella, M
2000-01-01
The alien hand syndrome, as originally defined, was used to describe cases involving anterior corpus callosal lesions producing involuntary movement and a concomitant inability to distinguish the affected hand from an examiner's hand when these were placed in the patient's unaffected hand. In recent years, acceptable usage of the term has broadened considerably, and has been defined as involuntary movement occurring in the context of feelings of estrangement from or personification of the affected limb or its movements. Three varieties of alien hand syndrome have been reported, involving lesions of the corpus callosum alone, the corpus callosum plus dominant medial frontal cortex, and posterior cortical/subcortical areas. A patient with posterior alien hand syndrome of vascular aetiology is reported and the findings are discussed in the light of a conceptualisation of posterior alien hand syndrome as a disorder which may be less associated with specific focal neuropathology than are its callosal and callosal-frontal counterparts.?? PMID:10601408
Factors influencing the treatment of posterior cruciate ligament injury.
Ittivej, Kittimasak; Prompaet, Sureeporn; Rojanasthien, Sattaya
2005-10-01
The primary objective was to determine the factors which influence the requirement of surgical treatment of posterior cruciate ligament (PCL) injury. Ninety one PCL injured patients diagnosed in the "Sports Medicine Clinic", Maharaj Nakorn Chiang Mai Hospital from January 1998 to December 2000 were included in the present study. There were 63 males and 28 females with an average age of 29 years. All of the PCL-insufficient knees were initially treated by non-operative method including 3 phases of rehabilitation. They were followed through to the end of December 2003. Analysis showed that the degree of posterior laxity was the only factor that had a statistical significant correlation to failure of conservative treatment. In addition, the need for surgical treatment was not associated with gender age, cause of injury, and concomitant of injury. The authors concluded that PCL injured patients with posterior laxity greater than 10 millimeters should be treated by PCL reconstruction. PMID:16871661
A Catalog of Transit Timing Posterior Distributions for all Kepler Planet Candidate Events
NASA Astrophysics Data System (ADS)
Montet, Benjamin Tyler; Becker, Juliette C.; Johnson, John
2015-08-01
Kepler has ushered in a new era of planetary dynamics, enabling the detection of interactions between multiple planets in transiting systems for hundreds of systems. These interactions, observed as transit timing variations (TTVs), have been used to find non-transiting companions to transiting systems and to measure masses, eccentricities, and inclinations of transiting planets. Often, physical parameters are inferred by comparing the observed light curve to the result of a photodynamical model, a time-intensive process that often ignores the effects of correlated noise in the light curve. Catalogs of transit timing observations have previously neglected non-Gaussian uncertainties in the times of transit, uncertainties in the transit shape, and short cadence data. Here, we present a catalog of not only times of transit centers, but also posterior distributions on the time of transit for every planet candidate transit event in the Kepler data, developed through importance sampling of each transit. This catalog allows us to marginalize over uncertainties in the transit shape and incorporate short cadence data, the effects of correlated noise, and non-Gaussian posteriors. Our catalog will enable dynamical studies that reflect accurately the precision of Kepler and its limitations without requiring the computational power to model the light curve completely with every integration.
van Eeden, F J; Palacios, I M; Petronczki, M; Weston, M J; St Johnston, D
2001-08-01
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
Profitable capitation requires accurate costing.
West, D A; Hicks, L L; Balas, E A; West, T D
1996-01-01
In the name of costing accuracy, nurses are asked to track inventory use on per treatment basis when more significant costs, such as general overhead and nursing salaries, are usually allocated to patients or treatments on an average cost basis. Accurate treatment costing and financial viability require analysis of all resources actually consumed in treatment delivery, including nursing services and inventory. More precise costing information enables more profitable decisions as is demonstrated by comparing the ratio-of-cost-to-treatment method (aggregate costing) with alternative activity-based costing methods (ABC). Nurses must participate in this costing process to assure that capitation bids are based upon accurate costs rather than simple averages. PMID:8788799
Time-Accurate Computational Simulation
NASA Technical Reports Server (NTRS)
Pao, S. Paul; Buning, Pieter G.
2004-01-01
Time accurate CFD may offer a faster approach to S&C aerodynamic database population than the conventional point by point steady state CFD. We would directly simulate -, -sweeps or other configuration movements typically of measurement sequence in wind tunnels. A second objective is to demonstrate potential applications to assessment of S&C dynamic derivatives by simulating vehicle motions such as free to roll, and nonlinearity such as the trends of aerodynamic forces near CL-max or flow hysteresis.
Rare association of fetal posterior urethral valve with ureteric stricture
Pradhan, Mandakini; Singh, Neeta; Singh, Asha Kumari; Kumari, Neeraj
2012-01-01
Background Amongst the various causes of obstructive uropathies, pelviureteric junction obstruction, bilateral ureterovesical junction obstruction and vesicoureteral reflux are common. The association of posterior urethral valve and ureteric stricture has not been reported so far. Case We report a rare case of fetal obstructive uropathy presenting as combination of ureteric stricture with posterior urethral valve and its consequences like cystic dysplastic kidneys and urinoma. Conclusion Combination of urinary malformation may be due to basic primary pathology and its secondary consequence at a distant site. PMID:22905302
Popliteal artery laceration during arthroscopic posterior cruciate ligament reconstruction.
Makino, Arturo; Costa-Paz, Matias; Aponte-Tinao, Luis; Ayerza, Miguel A; Muscolo, D Luis
2005-11-01
We report a case of acute laceration of the popliteal artery during an arthroscopic posterior cruciate ligament reconstruction. This injury can occur during the creation of the posteromedial portal, the manipulation of the tissues in the posterior part of the capsule of the knee joint, or when drilling the tibial hole. We recommend that a qualified vascular surgeon should be immediately available at the time of the surgery. In case of suspecting the occurrence of a popliteal artery injury, the vascular surgeon should be immediately consulted and arteriography and vascular repair should be performed. PMID:16325093
Lee, Young-Kyun; Kim, Ki-Choul; Ha, Yong-chan; Koo, Kyung-Hoi
2015-05-01
We evaluated 70 patients (71 hips) who underwent complex total hip arthroplasty (THA) through the combined anterior and posterior approach. Sixty-five patients (32 dislocated hips and 34 ankylosed hips) were followed-up at a minimum of 3 years (median, 6 years; range, 3-10 years). Seven patients (10.6%), who had transient paresthesia on the anterior thigh, recovered within 3 months. All patients had a good clinical outcome in terms of range of motion, pain and recovery of walking. At the latest follow-up, all prostheses had bone-ingrown stability without any detectable wear or osteolysis. The combined approach allows an excellent exposure of the acetabulum for accurate cup alignment, leg lengthening and mobilization of joint in complex THA without trochanteric osteotomy, excessive abductor release and femoral shortening osteotomy. PMID:25682205
Nishino, A; Sakurai, Y; Niizuma, H; Satoh, H; Kayama, T
1991-04-01
A rare case of dissecting aneurysm of distal posterior inferior cerebellar artery (PICA) is reported. A 51-year-old woman was admitted to our hospital complaining of severe headache and nausea. CT scan revealed subarachnoid hemorrhage which was thicker in the posterior fossa. The vertebral angiography demonstrated an aneurysm on the telovelotonsillar segment (Lister's classification) of the left PICA. On the third day, the left suboccipital craniotomy was performed and the fusiform aneurysm was resected. The postoperative course was uneventful. Histological examination of the resected aneurysm showed a dissection between the ruptured elastic lamina and the tunica media. Dissecting aneurysm of distal PICA is still belong to a rare entity. In all three cases found in the literature, the dissecting aneurysms are sited in the anterior medullary segment of PICA. Probably, this is the first report described a dissecting aneurysm on the more distal part-telovelotonsillar segment of PICA. The clinical features, pathogenesis and treatment of intracranial dissecting aneurysms are briefly discussed with reviewing the literature. PMID:1888578
Fast and accurate database searches with MS-GF+Percolator
Granholm, Viktor; Kim, Sangtae; Navarro, Jose' C.; Sjolund, Erik; Smith, Richard D.; Kall, Lukas
2014-02-28
To identify peptides and proteins from the large number of fragmentation spectra in mass spectrometrybased proteomics, researches commonly employ so called database search engines. Additionally, postprocessors like Percolator have been used on the results from such search engines, to assess confidence, infer peptides and generally increase the number of identifications. A recent search engine, MS-GF+, has previously been showed to out-perform these classical search engines in terms of the number of identified spectra. However, MS-GF+ generates only limited statistical estimates of the results, hence hampering the biological interpretation. Here, we enabled Percolator-processing for MS-GF+ output, and observed an increased number of identified peptides for a wide variety of datasets. In addition, Percolator directly reports false discovery rate estimates, such as q values and posterior error probabilities, as well as p values, for peptide-spectrum matches, peptides and proteins, functions useful for the whole proteomics community.
Fast and accurate database searches with MS-GF+Percolator.
Granholm, Viktor; Kim, Sangtae; Navarro, José C F; Sjölund, Erik; Smith, Richard D; Käll, Lukas
2014-02-01
One can interpret fragmentation spectra stemming from peptides in mass-spectrometry-based proteomics experiments using so-called database search engines. Frequently, one also runs post-processors such as Percolator to assess the confidence, infer unique peptides, and increase the number of identifications. A recent search engine, MS-GF+, has shown promising results, due to a new and efficient scoring algorithm. However, MS-GF+ provides few statistical estimates about the peptide-spectrum matches, hence limiting the biological interpretation. Here, we enabled Percolator processing for MS-GF+ output and observed an increased number of identified peptides for a wide variety of data sets. In addition, Percolator directly reports p values and false discovery rate estimates, such as q values and posterior error probabilities, for peptide-spectrum matches, peptides, and proteins, functions that are useful for the whole proteomics community. PMID:24344789
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, 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...
NASA Astrophysics Data System (ADS)
Gudder, Stanley
1988-02-01
A mathemetical framework for a realistic quantum probability theory is presented. The basic elements of this framework are measurements and amplitudes. Definitions of the various concepts are motivated by guidelines from the path integral formalism for quantum mechanics. The operational meaning of these concepts is discussed. Superpositions of amplitude functions are investigated and superselection sectors are shown to occur in a natural way. It is shown that this framework includes traditional nonrelativistic quantum mechanics as a special case. Proofs of most of the theorems will appear elsewhere.
Seyal, M; Kraft, L W; Gabor, A J
1987-08-01
We have demonstrated the presence of a localized, synapse-dependent negativity (N29) recorded over the upper cervical spine after bilateral stimulation of the posterior tibial nerves at the ankle. The amplitude of N29 is maximal at the level of the second cervical spine and decreases at more rostral and caudal levels. The peak latency of N29 remains constant at all levels. N29 has a long refractory period when compared with the refractory period of the afferent volley recorded at either the sacral or thoracic level. N29 is most likely generated by activation of the nucleus gracilis by the afferent volley. The cervical N13 after median nerve stimulation probably has multiple generator sites, including the nucleus cuneatus. PMID:3614672
Estimation of a benchmark dose in the presence or absence of hormesis using posterior averaging.
Kim, Steven B; Bartell, Scott M; Gillen, Daniel L
2015-03-01
U.S. Environment Protection Agency benchmark doses for dichotomous cancer responses are often estimated using a multistage model based on a monotonic dose-response assumption. To account for model uncertainty in the estimation process, several model averaging methods have been proposed for risk assessment. In this article, we extend the usual parameter space in the multistage model for monotonicity to allow for the possibility of a hormetic dose-response relationship. Bayesian model averaging is used to estimate the benchmark dose and to provide posterior probabilities for monotonicity versus hormesis. Simulation studies show that the newly proposed method provides robust point and interval estimation of a benchmark dose in the presence or absence of hormesis. We also apply the method to two data sets on carcinogenic response of rats to 2,3,7,8-tetrachlorodibenzo-p-dioxin. PMID:25384940
?i?man, Lokman; Türkmen, Faik; Efe, Duran; Pekince, O?uzhan; Göncü, Recep Gani; Sever, Cem
2015-01-01
Study Design A single-center, retrospective patient review of clinical and radiological outcomes of microsurgical posterior lumbar interbody fusion and decompression, without posterior instrumentation, for the treatment of lateral recess stenosis. Purpose This study documented the clinical and radiological results of microsurgical posterior lumbar interbody fusion and decompression of the lateral recess using interbody cages without posterior instrumentation for the treatment of lateral recess stenosis. Overview of Literature Although microsurgery has some advantages, various complications have been reported following microsurgical decompression, including cage migration, pseudoarthrosis, neurologic deficits, and persistent pain. Methods A total of 34 patients (13 men, 21 women), with a mean age of 56.65±9.1 years (range, 40-77 years) confirmed spinal stability, and preoperative radiological findings of lateral recess stenosis, were included in the study. Interbody polyetheretherketone cages and auto grafts were used in all patients. Posterior instrumentation was not used because of limited resection of the posterior lumbar structures. Preoperative and postoperative radiographs, computed tomography scans, and magnetic resonance imaging were assessed and compared to images taken at the final follow-up. Functional recovery was also evaluated according to the Macnab criteria at the final follow-up. Results The average follow-up time was 35.05±8.65 months (range, 24-46 months). The clinical results, operative time, intraoperative blood loss, and duration of hospital stay were similar to previously published results; the fusion rate (85.2%) was decreased and the migration rate (5.8%) was increased, compared with prior reports. Conclusions Although microsurgery has some advantages, migration and pseudoarthrosis remain challenges to achieving adequate lumbar interbody fusion.
Modern posterior screw techniques in the pediatric cervical spine
Hedequist, Daniel J
2014-01-01
Treatment of children with cervical spine disorders requiring fusion is a challenging endeavor for a variety of reasons. The size of the patients, the corresponding abnormal bony anatomy, the inherent ligamentous laxity of children, and the relative rarity of the disorders all play a part in difficulty of treatment. The benefits of modern posterior cervical instrumentation in children, defined as rigid screw-rod systems, have been shown to be many including: improved arthrodesis rates, diminished times in halo-vest immobilization, and improved reduction of deformities. The anatomy of children and the corresponding pathology seen frequently is at the upper cervical spine and craniocervical junction given the relatively large head size of children and the horizontal facets at these regions predisposing them to instability or deformity. Posterior screw fixation, while challenging, allows for a rigid base to allow for fusion in these upper cervical areas which are predisposed to pseudarthrosis with non-rigid fixation. A thorough understanding of the anatomy of the cervical spine, the morphology of the cervical spine, and the available screw options is paramount for placing posterior cervical screws in children. The purpose of this review is to discuss both the anatomical and clinical descriptions related to posterior screw placement in the cervical spine in children. PMID:24829871
Posterior Predictive Assessment of Item Response Theory Models
ERIC Educational Resources Information Center
Sinharay, Sandip; Johnson, Matthew S.; Stern, Hal S.
2006-01-01
Model checking in item response theory (IRT) is an underdeveloped area. There is no universally accepted tool for checking IRT models. The posterior predictive model-checking method is a popular Bayesian model-checking tool because it has intuitive appeal, is simple to apply, has a strong theoretical basis, and can provide graphical or numerical…
Posterior Cortical Atrophy Presenting with Superior Arcuate Field Defect
Wan, Sue Ling; Bukowska, Danuta M.; Ford, Stephen; Chen, Fred K.
2015-01-01
An 80-year-old female with reading difficulty presented with progressive arcuate field defect despite low intraocular pressure. Over a 5-year period, the field defect evolved into an incongruous homonymous hemianopia and the repeated neuroimaging revealed progressive posterior cortical atrophy. Further neuropsychiatric assessment demonstrated symptoms and signs consistent with Benson's syndrome. PMID:26417467
Closed posterior dislocation of the ankle without fracture
Agrawal, Alok C; Raza, HKT; Haq, RU
2008-01-01
Closed posterior dislocation of the ankle without a fracture is a rare injury. We are reporting a case in a young male on his motorbike, being hit at the right ankle from behind. The mechanisms of injury along with MRI findings are being discussed. PMID:19753168
Some Posterior Standard Deviations in Item Response Theory
ERIC Educational Resources Information Center
Kim, Seock-Ho
2007-01-01
The procedures required to obtain the approximate posterior standard deviations of the parameters in the three commonly used item response models for dichotomous items are described and used to generate values for some common situations. The results were compared with those obtained from maximum likelihood estimation. It is shown that the use of…
Is posterior fusion necessary with laminectomy in the cervical spine?
McAllister, Beck D.; Rebholz, Brandon J.; Wang, Jeffery C.
2012-01-01
Background: Cervical decompressive laminectomy is a common procedure for addressing multilevel cervical spine pathology. The most common reasons for performing simultaneous posterior cervical fusion include the prevention of progressive postlaminectomy kyphotic deformity or other types of instability which can contribute to late neurological deterioration. Methods: The medical literature (Pub Med with MeSH) concerning cervical laminectomy, posterior cervical fusion, and complications of laminectomy/fusion was reviewed. Additionally, references from the articles were queried to find additional literature. Results: Multiple studies concluded that cervical laminectomy versus laminectomy and fusion produced similar short-term postoperative outcomes. Careful patient selection was warranted to minimize the complications associated with cervical laminectomy alone; these included postoperative kyphosis (6–46%) and late deterioration (10–37%). The addition of a posterior cervical fusion was associated with relatively low complication rates, and avoided the evolution of late deformity or delayed neurological deterioration. Conclusion: Although the short-term results of cervical laminectomy versus laminectomy and fusion are similar, there appear to be more complications associated with performing laminectomy alone over the long term. Here, we reviewed the pros and cons of posterior cervical decompression alone versus decompression with fusion/instrumentation to treat cervical pathology, highlighting the complications associated with each surgical alternative. PMID:22905328
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
Posterior Predictive Model Checking for Multidimensionality in Item Response Theory
ERIC Educational Resources Information Center
Levy, Roy; Mislevy, Robert J.; Sinharay, Sandip
2009-01-01
If data exhibit multidimensionality, key conditional independence assumptions of unidimensional models do not hold. The current work pursues posterior predictive model checking, a flexible family of model-checking procedures, as a tool for criticizing models due to unaccounted for dimensions in the context of item response theory. Factors…
Predictor variables for forward scapular posture including posterior shoulder tightness.
Lee, Ji-Hyun; Cynn, Heon-seock; Yi, Chung-Hwi; Kwon, Oh-yun; Yoon, Tae-Lim
2015-04-01
The purpose of this study was (1) to determine the relationships between the degree of forward scapular posture and the pectoralis minor index, the strength of the serratus anterior, the thoracic spine angle, and posterior shoulder tightness, and (2) to identify predictors of forward scapular posture, including posterior shoulder tightness. The study recruited eighteen subjects with forward scapular posture and objectively measured the acromion distance, the pectoralis minor index, and the strength of the serratus anterior muscle of each participant. The amount of glenohumeral horizontal adduction and internal rotation were evaluated to measure posterior shoulder tightness. There were high intra-rater reliabilities in all measurements. The measurement results showed a statistically strong negative correlation between the degree of forward scapular posture and the pectoralis minor index. They also revealed a moderate positive correlation between the degree of forward scapular posture and the thoracic spine angle and a moderate negative relationship between the degree of forward scapular posture and the amount of the glenohumeral horizontal adduction. A multiple regression analysis indicated that a total multiple regression model explained 93% of the amount of forward scapular posture. All predictor variables, including posterior shoulder tightness, should be considered while assessing, managing, and preventing forward scapular posture. PMID:25892380
Hypertonic saline test for the investigation of posterior pituitary function
Angelika Mohn; Carlo L Acerini; Timothy D Cheetham; Stafford L Lightman; David B Dunger
1998-01-01
The hypertonic saline test is a useful technique for distinguishing partial diabetes insipidus from psychogenic polydipsia, and for the diagnosis of complex disorders of osmoreceptor and posterior pituitary function. However, there is little information concerning its use in childhood. The experience of using this test in five children (11 months to 18 years) who presented diagnostic problems is reported. In
The treatment of trigeminal neuralgia by posterior fossa microsurgery
C B Adams; A H Kaye; P J Teddy
1982-01-01
Between 1972 and 1981 57 patients underwent posterior fossa exploration in Oxford by a single surgeon for the treatment of trigeminal neuralgia. Fifty-four of these had either partial or total section of the trigeminal sensory root, 2 had microvascular decompression operations and one had both a partial sensory root section and microvascular decompression. There was no mortality and no significant
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
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…
Linear Transformation of Multivariate Normal Distribution: Marginal, Joint and Posterior
Linear Transformation of Multivariate Normal Distribution: Marginal, Joint and Posterior Li is from normal distribution N(µx, x) and y = Ax + b, where b is from N(0, b). In this note, we show integrals, we uses several special properties of normal distribution to make the derivation. 1 Linear
Mutism after posterior fossa surgery. Review of the literature
Miguel Gelabert-González; Juan Fernández-Villa
2001-01-01
Mutism is an infrequent and transitory complication observed following posterior fossa surgery. Patients become mute in the immediate postoperative period, with restoration of speech within a few weeks. A review of the literature disclosed 157 patients with this condition. The anatomical structures thought to be involved are the connections between the cerebella dentate nucleous, the ventrolateral nucleous of the contalateral
Cognitive Set Reconfiguration Signaled by Macaque Posterior Parietal Neurons
Miyashita, Yasushi
Neuron Article Cognitive Set Reconfiguration Signaled by Macaque Posterior Parietal Neurons Tsukasa sets. To elucidate how this dynamic process is implemented in the primate brain, single-unit activity the monkeys to promptly perform set shifting, mostly within a single trial, and found shift-related activity
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,
1976-01-01
Electron microscope observations of thin sections of epoxy resin- embeded posterior silk gland cells at the later stage of the fifth instar revealed that the Golgi vacuoles and the secretory granules (fibroin globules) in the cytoplasm and the glandular lumen contain fine fibrous materials. In frozen thin sections these structures appear as electron-dense granules and electron-dense blocks, or a column, respectively. Immunoelectron microscopy has shown that ferritin particles or products of the peroxidase reaction are localized on these structures. It was concluded that the fine fibrous materials most probably represent native fibroin molecules or their aggregates. PMID:783174
Efficient and accurate fragmentation methods.
Pruitt, Spencer R; Bertoni, Colleen; Brorsen, Kurt R; Gordon, Mark S
2014-09-16
Conspectus Three novel fragmentation methods that are available in the electronic structure program GAMESS (general atomic and molecular electronic structure system) are discussed in this Account. The fragment molecular orbital (FMO) method can be combined with any electronic structure method to perform accurate calculations on large molecular species with no reliance on capping atoms or empirical parameters. The FMO method is highly scalable and can take advantage of massively parallel computer systems. For example, the method has been shown to scale nearly linearly on up to 131?000 processor cores for calculations on large water clusters. There have been many applications of the FMO method to large molecular clusters, to biomolecules (e.g., proteins), and to materials that are used as heterogeneous catalysts. The effective fragment potential (EFP) method is a model potential approach that is fully derived from first principles and has no empirically fitted parameters. Consequently, an EFP can be generated for any molecule by a simple preparatory GAMESS calculation. The EFP method provides accurate descriptions of all types of intermolecular interactions, including Coulombic interactions, polarization/induction, exchange repulsion, dispersion, and charge transfer. The EFP method has been applied successfully to the study of liquid water, ?-stacking in substituted benzenes and in DNA base pairs, solvent effects on positive and negative ions, electronic spectra and dynamics, non-adiabatic phenomena in electronic excited states, and nonlinear excited state properties. The effective fragment molecular orbital (EFMO) method is a merger of the FMO and EFP methods, in which interfragment interactions are described by the EFP potential, rather than the less accurate electrostatic potential. The use of EFP in this manner facilitates the use of a smaller value for the distance cut-off (Rcut). Rcut determines the distance at which EFP interactions replace fully quantum mechanical calculations on fragment-fragment (dimer) interactions. The EFMO method is both more accurate and more computationally efficient than the most commonly used FMO implementation (FMO2), in which all dimers are explicitly included in the calculation. While the FMO2 method itself does not incorporate three-body interactions, such interactions are included in the EFMO method via the EFP self-consistent induction term. Several applications (ranging from clusters to proteins) of the three methods are discussed to demonstrate their efficacy. The EFMO method will be especially exciting once the analytic gradients have been completed, because this will allow geometry optimizations, the prediction of vibrational spectra, reaction path following, and molecular dynamics simulations using the method. PMID:24810424
Reality and Probability: Introducing a New Type of Probability Calculus
Aerts, Diederik
Reality and Probability: Introducing a New Type of Probability Calculus Diederik Aerts Center Leo 33, 1160 Brussels, Belgium. diraerts@vub.ac.be Abstract We consider a conception of reality our overall experience with the world. If we consider a conception of reality where probability plays
Probabilities for Solar Siblings
NASA Astrophysics Data System (ADS)
Valtonen, Mauri; Bajkova, A. T.; Bobylev, V. V.; Mylläri, A.
2015-02-01
We have shown previously (Bobylev et al. Astron Lett 37:550-562, 2011) that some of the stars in the solar neighborhood today may have originated in the same star cluster as the Sun, and could thus be called Solar Siblings. In this work we investigate the sensitivity of this result to galactic models and to parameters of these models, and also extend the sample of orbits. There are a number of good candidates for the sibling category, but due to the long period of orbit evolution since the break-up of the birth cluster of the Sun, one can only attach probabilities of membership. We find that up to 10 % (but more likely around 1 %) of the members of the Sun's birth cluster could be still found within 100 pc from the Sun today.
Robotic Posterior Mitral Leaflet Repair: Neochordal versus Resectional Techniques
Mihaljevic, Tomislav; Pattakos, Gregory; Gillinov, A. Marc; Bajwa, Gurjyot; Planinc, Mislav; Williams, Sarah J.; Blackstone, Eugene H.
2013-01-01
Background Resectional techniques are the established method of posterior mitral valve leaflet repair for degenerative disease; however, use of neochordae in a robotically assisted approach is gaining acceptance because of its versatility for difficult multi-segment disease. The purposes of this study were to compare the versatility, safety, and effectiveness of neochordal vs. resectional techniques for robotic posterior mitral leaflet repair. Methods From 12/2007 to 7/2010, 334 patients underwent robotic posterior mitral leaflet repair for degenerative disease by a resectional (n=248) or neochordal (n=86) technique. Outcomes were compared unadjusted and after propensity score matching. Results Neochordae were more likely to be used than resection in patients with two (28% vs. 13%, P=.002) or three (3.7% vs. 0.87%, P=.08) diseased posterior leaflet segments. Three resection patients (0.98%) but no neochordal patient required reoperation for hemodynamically significant systolic anterior motion (SAM). Residual mitral regurgitation (MR) at hospital discharge was similar for matched neochordal vs. resection patients (P=.14) (MR 0+, 82% vs. 89%; MR 1+, 14% vs. 8.2%; MR 2+, 2.3% vs. 2.6%; one neochordal patient had 4+ MR and was reoperated). Among matched patients, postoperative mortality and morbidity were similarly low. Conclusion Compared with a resectional technique, robotic posterior mitral leaflet repair with neochordae is associated with shorter operative times and no occurrence of SAM. The versatility, effectiveness, and safety of this repair make it a good choice for patients with advanced multi-segment disease. PMID:23103008
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
Axial Spondylectomy and Circumferential Reconstruction via a Posterior Approach
Jandial, Rahul; Kelly, Brandon; Bucklen, Brandon; Khalil, Saif; Chen, Mike Y.
2013-01-01
Background Spinal metastases of the second cervical vertebra are a subset of tumors that is particularly difficult to address surgically. Previously described techniques require highly morbid circumferential dissection posterior to the pharynx for resection and reconstruction. Objective To perform a biomechanical analysis of instrumented reconstruction configurations used after axial spondylectomy and demonstrate safe use of a novel construct in a patient case report. Methods Several different published and novel reconstruction configurations were inserted into 7 occipitocervical spines that underwent axial spondylectomy. A biomechanical analysis of the constructs’ stiffness in flexion and extension, lateral bending, and rotation was performed. A patient then underwent a posterior-only approach for axial spondylectomy and circumferential reconstruction. Results Biomechanical analysis of different constructs demonstrated that anterior column reconstruction with bilateral cages spanning C1 lateral mass to C3 facet in combination with occipitocervical instrumentation was superior in flexion-extension and equivalent in lateral bending and rotation to currently used constructs. In the patient in which this construct was placed via a posterior-only approach for axial spondylectomy and instrumentation, the patient remained at neurological baseline and demonstrated no recurrence of local disease or failure of instrumentation to date. Conclusion When comparing C1 lateral mass to C3 facet bilateral cage plus occipitocervical instrumentation to existing anterior and posterior constructs, this novel reconstruction is biomechanically equivalent if not superior in performance. In a patient, the posterior-only approach for C2 spondylectomy with the novel reconstruction was safe, durable, and avoided the morbidity of the anterior approach. PMID:23149951
Anterior and posterior corneal stroma elasticity assessed using nanoindentation
Dias, Janice; Ziebarth, Noël M.
2013-01-01
Corneal biomechanics is an essential parameter for developing diagnostic and treatment methods of corneal-related diseases. It is widely accepted that corneal mechanical strength stems from the stroma's collagenous composition. However, more comprehensive insight into the mechanical properties within the stroma is needed to improve current corneal diagnostic and treatment techniques. The purpose of this study was to perform elasticity characterization of anterior and posterior stromal regions of human corneas using atomic force microscopy (AFM). Nine pairs of human whole globes were placed in 20% Dextran solution, cornea side down, to restore the corneal thickness to physiological levels (400-600?m). The epithelium and Bowman's membrane were removed from all eyes. Anterior stromal AFM elasticity testing was then performed on left (OS) eyes. Additional stroma was removed from right (OD) eyes to allow posterior stromal measurements at a depth of 50% of the original thickness. All experiments were performed with corneas submerged in 15% Dextran to maintain corneal hydration. The results of the study showed that the Young's modulus of elasticity of the anterior stroma (average: 281 ± 214kPa; range: 59-764kPa) was significantly higher than that of the posterior stroma (average: 89.5 ± 46.1kPa; range: 29-179kPa) (p=0.014). In addition, a linear relationship was found between the posterior stromal elasticity and anterior stromal elasticity (p=0.0428). On average, the elasticity of the posterior stroma is 39.3% of the anterior stroma. In summary, there appears to be an elasticity gradient within the corneal stroma, which should be considered in the design and development of corneal diagnostic and treatment methods to enhance efficacy. PMID:23800511
Laparoscopic adrenalectomy: lateral transabdominal approach vs posterior retroperitoneal approach.
Yoneda, K; Shiba, E; Watanabe, T; Akazawa, K; Shimazu, K; Takamura, Y; Kim, S; Tsukamoto, F; Tanji, Y; Taguchi, T; Noguchi, S
2000-06-01
Laparoscopic adrenalectomy has been used to remove a wide variety of adrenal neoplasms. Although several laparoscopic approaches to the adrenal gland have been described, the lateral transabdominal approach has several advantages when compared with other approaches for laparoscopic adrenalectomy. From October 1995 to July 1999, we performed laparoscopic adrenalectomies on 16 patients, including eight posterior retroperitoneal approaches and eight lateral transabdominal approaches. Sixteen patients, ranging in age from 23 to 69 years, were treated for the following conditions: non-functioning adenoma, four patients; aldosteronoma, seven patients; pheochromocytoma, three patients; Cushing's adenoma, two patients. The average tumor size was 2.5 +/- 0.5 cm (1.8-3.0 cm, median 2.4 cm) in the lateral transabdominal approach, 1.2 +/- 0.8 cm (0.8-3.2 cm, median 1.75 cm) in the posterior retroperitoneal approach. Average operative time of lateral transabdominal approach was significantly shorter than that of the posterior retroperitoneal approaches (mean 129 min vs 269 min, P = 0.0005). Conversion to laparotomy was required in one patient in the posterior approach. Postoperative complication occurred in one pneumothorax in the lateral transabdominal approach and two subcutaneous emphysemas in the posterior retroperitoneal approach. There was no statistical difference in blood loss during the operation in the two groups. There was no mortality in either group. The lateral transabdominal approach is a safe and efficient technique for the removal of the adrenal neoplasms. Compared with other approaches, this technique has a wider working space and also good exposure for removing the adrenal gland. PMID:10915028
Logic, Geometry And Probability Theory
Federico Holik
2013-11-29
We discuss the relationship between logic, geometry and probability theory under the light of a novel approach to quantum probabilities which generalizes the method developed by R. T. Cox to the quantum logical approach to physical theories.
Machine Learning ! ! ! ! !Srihari Probability Theory
and manipulation of uncertainty 2 apples 3 oranges 3 apples 1 orange Box is random variable B (has values r or b? Â· Conditional Probability ÂGiven that we have an orange what is the probability that we chose the blue box? Â· Joint Probability ÂWhat is the probability of orange AND blue box? 2 apples 3 oranges 3 apples 1 orange
STATISTICS AND PHILOSOPHY OF PROBABILITY
Burdzy, Krzysztof "Chris"
STATISTICS AND PHILOSOPHY OF PROBABILITY -- SIX DEGREES OF SEPARATION Krzysztof Burdzy University of Washington Krzysztof Burdzy Philosophy of probability #12;The search for certainty The search for certainty. On the clash of science and philosophy of probability. Preface, Table of Contents and Introduction
Probability and Chance Michael Strevens
Strevens, Michael
Probability and Chance Michael Strevens For the Macmillan Encyclopedia of Philosophy, second is forearmed: expecting a hurricane, before leaving home you pack your hurricane lantern. Probability enters into this scenario twice, first in the form of a physical probability, sometimes called a chance, quantifying certain
The Probability of Causal Conditionals
ERIC Educational Resources Information Center
Over, David E.; Hadjichristidis, Constantinos; Evans, Jonathan St. B. T.; Handley, Simon J.; Sloman, Steven A.
2007-01-01
Conditionals in natural language are central to reasoning and decision making. A theoretical proposal called the Ramsey test implies the conditional probability hypothesis: that the subjective probability of a natural language conditional, P(if p then q), is the conditional subjective probability, P(q [such that] p). We report three experiments on…
Quantum Foundations : Is Probability Ontological ?
Elemer E Rosinger
2010-07-24
It is argued that the Copenhagen Interpretation of Quantum Mechanics, founded ontologically on the concept of probability, may be questionable in view of the fact that within Probability Theory itself the ontological status of the concept of probability has always been, and is still under discussion.
Probability theory, not the very guide of life.
Juslin, Peter; Nilsson, Håkan; Winman, Anders
2009-10-01
Probability theory has long been taken as the self-evident norm against which to evaluate inductive reasoning, and classical demonstrations of violations of this norm include the conjunction error and base-rate neglect. Many of these phenomena require multiplicative probability integration, whereas people seem more inclined to linear additive integration, in part, at least, because of well-known capacity constraints on controlled thought. In this article, the authors show with computer simulations that when based on approximate knowledge of probabilities, as is routinely the case in natural environments, linear additive integration can yield as accurate estimates, and as good average decision returns, as estimates based on probability theory. It is proposed that in natural environments people have little opportunity or incentive to induce the normative rules of probability theory and, given their cognitive constraints, linear additive integration may often offer superior bounded rationality. PMID:19839686
The effect of laser fluctuation statistics upon detection probability
A. M. Wedd; J. C. Thomas; J. A. Hermann
1996-01-01
The effects of laser beam irradiance fluctuations, such as speckle and scintillation, upon optical beam detection probability are examined in an entirely statistical context. The optical detector is assumed to possess a non-linear integrated log-normal response function, as is normally ascribed to the eye. Various statistical distribution functions purported to model these fluctuations accurately are examined from both numerical and
NASA Astrophysics Data System (ADS)
Vrugt, J. A.
2011-04-01
Formal and informal Bayesian approaches are increasingly being used to treat forcing, model structural, parameter and calibration data uncertainty, and summarize hydrologic prediction uncertainty. This requires posterior sampling methods that approximate the (evolving) posterior distribution. We recently introduced the DiffeRential Evolution Adaptive Metropolis (DREAM) algorithm, an adaptive Markov Chain Monte Carlo (MCMC) method that is especially designed to solve complex, high-dimensional and multimodal posterior probability density functions. The method runs multiple chains in parallel, and maintains detailed balance and ergodicity. Here, I present the latest algorithmic developments, and introduce a discrete sampling variant of DREAM that samples the parameter space at fixed points. The development of this new code, DREAM(D), has been inspired by the existing class of integer optimization problems, and emerging class of experimental design problems. Such non-continuous parameter estimation problems are of considerable theoretical and practical interest. The theory developed herein is applicable to DREAM(ZS) (Vrugt et al., 2011) and MT-DREAM(ZS) (Laloy and Vrugt, 2011) as well. Two case studies involving a sudoku puzzle and rainfall - runoff model calibration problem are used to illustrate DREAM(D).
Physics with exotic probability theory
Saul Youssef
2001-12-06
Probability theory can be modified in essentially one way while maintaining consistency with the basic Bayesian framework. This modification results in copies of standard probability theory for real, complex or quaternion probabilities. These copies, in turn, allow one to derive quantum theory while restoring standard probability theory in the classical limit. The argument leading to these three copies constrain physical theories in the same sense that Cox's original arguments constrain alternatives to standard probability theory. This sequence is presented in some detail with emphasis on questions beyond basic quantum theory where new insights are needed.
Epstein, Nancy E.
2014-01-01
What are the risks, benefits, alternatives, and pitfalls for operating on cervical ossification of the posterior longitudinal ligament (OPLL)? To successfully diagnose OPLL, it is important to obtain Magnetic Resonance Images (MR). These studies, particularly the T2 weighted images, provide the best soft-tissue documentation of cord/root compression and intrinsic cord abnormalities (e.g. edema vs. myelomalacia) on sagittal, axial, and coronal views. Obtaining Computed Tomographic (CT) scans is also critical as they best demonstrate early OPLL, or hypertrophied posterior longitudinal ligament (HPLL: hypo-isodense with punctate ossification) or classic (frankly ossified) OPLL (hyperdense). Furthermore, CT scans reveal the “single layer” and “double layer” signs indicative of OPLL penetrating the dura. Documenting the full extent of OPLL with both MR and CT dictates whether anterior, posterior, or circumferential surgery is warranted. An adequate cervical lordosis allows for posterior cervical approaches (e.g. lamionplasty, laminectomy/fusion), which may facilitate addressing multiple levels while avoiding the risks of anterior procedures. However, without lordosis and with significant kyphosis, anterior surgery may be indicated. Rarely, this requires single/multilevel anterior cervical diskectomy/fusion (ACDF), as this approach typically fails to address retrovertebral OPLL; single or multilevel corpectomies are usually warranted. In short, successful OPLL surgery relies on careful patient selection (e.g. assess comorbidities), accurate MR/CT documentation of OPLL, and limiting the pros, cons, and complications of these complex procedures by choosing the optimal surgical approach. Performing OPLL surgery requires stringent anesthetic (awake intubation/positioning) and also the following intraoperative monitoring protocols: Somatosensory evoked potentials (SSEP), motor evoked potentials (MEP), and electromyography (EMG). PMID:24843819
Biomechanic effect of posterior cruciate ligament rupture on lateral meniscus
Lei, Pengfei; Sun, Rongxin; Hu, Yihe; Li, Kanghua; Liao, Zhan
2015-01-01
Objective: This study aims to investigate the biomechanical effect of posterior cruciate ligament (PCL) rupture on lateral meniscus. Method: The stresses of anterior horn, caudomedial part and posterior horn of lateral meniscus in cadaveric knees were recorded when the knee joints were loaded 200 to 1000 N at 0, 30, 60 and 90° of flexion. Twelve knees were tested before PCL transection (intact group), and 6 each were then tested after anterolateral bundle (ALB group) and postmedial bundle (PMB group) transection. The same knees were finally tested after complete PCL transection. Result: At 0°of knee flexion, the stresses of the anterior horn, caudomedial part and posterior horn were negative and compressive, and were not significantly different between intact and ALB groups, and between completely transected and PMB groups at 200 and 400 N. The stresses of the anterior horn and caudomedial part were greater in completely transected and PMB groups than in intact and ALB groups. The stresses of the posterior horn were smaller in PMB and completely transected groups than in intact and ALB groups. At 600-1000 N, the stresses were significantly different between the groups. The absolute stresses of the anterior horn and caudomedial part were in order of completely transected > PMB > ALB > intact group, while these of the posterior horn were reversed. At 30° of knee flexion, the stresses of the three parts were not significantly different between intact and PMB groups nor between completely transected and ALB groups at 200 and 400 N. The stresses in the anterior horn and caudomedial part were negative and different between completely transected and ALB groups, and positive and different between intact and PMB groups. The stresses in the posterior horn were positive and different between completely transected and ALB groups, and negative and different between intact and PMB groups. At loads of > 600 N, the stresses in the anterior horn and caudomedial part were negative in completely transected and ALB groups, and positive in intact and PMB groups. The stresses of the posterior horn were positive in completely transected and ALB groups and negative in intact and PMB groups, with significant difference between the groups. At 60° and 90° of flexion, the stresses of the anterior horn and caudomedial part were positive in completely transected and ALB groups and positive in intact and PMB groups, while the stresses of posterior horn were in the opposite directions and were significantly different between the groups at the same loads. Conclusion: Complete transection of PCL will result in stress changes in various parts of lateral meniscus. At 200 and 400 N, transection of ALB and PMB do not change the stress at 0° and 30° of flexion, respectively. At heavier loads (600-1000 N), the stresses at these angels are affected in ALB and PMB groups. At all loaded tested, transection of ALB and PMB results in changed stresses in all regions of lateral meniscus at 30-90° and 0-90° of flexion, respectively. PMID:26309636
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
Clinics in diagnostic imaging (129). Posterior cruciate ligament ganglion cyst.
See, P P L; Peh, W C G; Wong, L Y; Chew, K T
2009-11-01
Ganglion cysts arising from the posterior cruciate ligament (PCL) of the knee are rare. We describe a 21-year-old Chinese woman who presented with right knee pain following a twisting injury six months prior. Her pain was exacerbated by squatting, although her range of knee motion was full. Magnetic resonance imaging showed a lobulated, well-defined, T1-hypointense and T2-hyperintense, septated cystic mass arising from the posterior aspect of the PCL. The diagnosis of a PCL ganglion cyst was confirmed by computed tomography-guided aspiration of the cyst. Due to persistent mild knee pain, the patient eventually underwent arthroscopic decompression of the ganglion cyst. The clinical features, diagnosis and management of PCL ganglion cysts are discussed. PMID:19960168
Anterior-assisted levitation for the posteriorly dislocated intraocular lens.
Chee, Soon-Phaik
2009-06-01
I describe a technique to manage a subluxated crystalline lens or an in-the-bag posterior chamber intraocular lens (PC IOL) that tilts severely into the anterior or midvitreous cavity. In the absence of intervening vitreous presentation, a 27-gauge needle is inserted via a snugly fitting paracentesis incision to reach the anterior capsule of the posteriorly dislocated cataract or the anterior capsulorhexis rim of the PC IOL without disturbing the anterior chamber stability. With the bevel facing forward, the needle is introduced at an oblique angle and used to gently puncture the anterior capsule of the subluxated lens or insinuate between the fibrosed capsulorhexis rim and the optic of the subluxated PC IOL. The needle tip is brought forward and the anterior capsule grasped by microforceps introduced via another paracentesis wound. An ophthalmic viscosurgical device is then injected into the anterior chamber and the lens stabilized. PMID:19465280
Complications associated with posterior and transforaminal lumbar interbody fusion.
Chrastil, Jesse; Patel, Alpesh A
2012-05-01
Posterior lumbar interbody fusion and transforaminal lumbar interbody fusion are commonly performed to obtain a 360° arthrodesis through a posterior-only approach. These techniques are currently used in the management of spondylolisthesis, degenerative scoliosis, pseudarthrosis, recurrent disk herniation, and chronic low back pain with associated degenerative disk disease. Several adverse events have been described, including intraoperative neurologic injury, implant migration or subsidence, dural tears, infection, heterotopic ossification, BMP-related radiculitis, and osteolysis. Although the use of newer materials (eg, bone morphogenetic proteins) and procedures (eg, minimally invasive surgery) is on the rise, they are associated with unique concerns. Understanding the potential adverse events and steps that can be taken to prevent, detect, and manage complications is critical in patient counseling and perioperative decision making. PMID:22553100
Experimental posterior uveitis. I: A clinical, angiographic, and pathological study.
Stanford, M R; Brown, E C; Kasp, E; Graham, E M; Sanders, M D; Dumonde, D C
1987-08-01
The clinical, angiographic, and histopathological features of experimental posterior uveitis in the black hooded Lister rat are described. This mild form of experimental allergic uveoretinitis (EAU) is induced by sensitisation with retinal S antigen in Freund's complete adjuvant, and the inflammation produced is confined to the posterior segment of the eye. This allows for the first time precise photographic and angiographic documentation of the evolution of clinical signs, because there is minimal clouding of the vitreous by inflammatory cells. Clinically the disease is characterised by the appearance of disc oedema and periphlebitis, followed by focal infiltrates in the deep retinal layers, with eventual atrophy of the pigment epithelium. Histologically, retinal vasculitis is associated with focal mononuclear cell infiltration and necrosis of the photoreceptor layers. This model closely resembles the clinical features of idiopathic retinal vasculitis seen in man. PMID:3651374
Ureteral injury after posterior lumbar discectomy with interbody screw fixation
Pillai, Sunil Bhaskara; Hegde, Padmaraj; Venkatesh, Giridhar; Iyyan, Bhalaguru
2013-01-01
We report a case of iatrogenic ureteral injury secondary to L5 laminectomy and microdiscectomy with L5–S1 bone graft with posterior lumbar interbodyfusion using presacral cancellous screw fixation, managed by initial ureteral stent placement and subsequent Boari bladder flap repair. A 33-year-old woman underwent L5 laminectomy and microdiscectomy with L5–S1 bone graft with posterior lumbar interbody fusion using presacral cancellous screw fixation. On postoperative day 10, she developed lower abdominal pain, vomiting and fever. Ultrasonogram and contrast-enhanced CT demonstrated a large pelvic urinoma secondary to a right lower ureteric injury. This was managed initially by ureteral stent placement and subsequent Boari bladder flap repair. Ureteral injury following spinal surgery is a rare surgical complication with significant morbidity and mortality. A high index of suspicion is essential for early appropriate management and renal salvage. PMID:24105384
[Cysts in the posterior triangle of the neck in adults].
Brea-Álvarez, Beatriz; Roldán-Hidalgo, Amaya
2015-01-01
Cystic lesions of the posterior triangle are a pathologic entity whose diagnosis is made in the first two years of life. Its presentation in adulthood is an incidental finding and the differential diagnosis includes cystic lymphangioma, lymphatic metastasis of thyroid cancer and branchial cyst. Often with the finding of a cervical lump, FNA is made before diagnostic imaging is performed, however, this procedure is not always advisable. We reviewed the cases of patients who came last year to our department with a cystic mass in this location and correlating the imaging findings with pathologic specimen. We show characteristic findings of these lesions in order to make an early diagnosis and thus to get the approach and treatment appropriate of adult patients with a cystic lesion in the posterior cervical triangle. PMID:24846559
Therapeutic stratagems for vascular degenerative disorders of the posterior eye.
Jain, Gaurav K; Warsi, Musarrat H; Nirmal, Jayabalan; Garg, Vaidehi; Pathan, Shadab A; Ahmad, Farhan J; Khar, Roop K
2012-07-01
In this review we discuss insights into therapeutic stratagems that can selectively target the choroid, retinal cells and vitreoretinal space for the treatment of vision-threatening vascular degenerative disorders of the posterior eye. Despite the relative success of these novel drugs, new problems related to its delivery remain. Systems carrying drugs to the target site, such as nanoparticles, liposomes, vectosomes, spanlastics, micelles, dendrimers and implants are also discussed. Further, we also consider drug penetration enhancement approaches along with cutting-edge strategies for regaining vision during vision-threatening vascular degenerative disorders of the eye. Finally, challenges, such as ocular or even systemic complications associated with use of prolonged therapies and future prospects, such as combination of approaches with multidisciplinary integration to optimize delivery to the posterior eye are also addressed. PMID:22504325
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. PMID:26090117
Posterior urethral stricture repair following trauma and pelvic fracture.
Rios, Emilio; Martinez-Piñeiro, Luis; Álvarez-Maestro, Mario
2014-01-01
Posterior urethral injuries typically arise in the context of a pelvic fracture.The correct and appropriate initial treatment of associated urethral rupture is critical to the proper healing of the injury. In this paper, we provide a comprehensive review of the literature with special emphasis on the various treatments available: open or endoscopic primary realignment, immediate or delayed urethroplasty after suprapubic cystostomy, and delayed optical urethrotomy. PMID:24531674
Surgical treatment of thoracic disc herniations via tailored posterior approaches.
Börm, Wolfgang; Bäzner, U; König, R W; Kretschmer, T; Antoniadis, G; Kandenwein, J
2011-10-01
We present clinical findings, radiological characteristics and surgical modalities of various posterior approaches to thoracic disc herniations and report the clinical results in 27 consecutive patients. Within an 8-year period 27 consecutive patients (17 female, 10 male) aged 30-83 years (mean 53 years.) were surgically treated for 28 symptomatic herniated thoracic discs in our department. Six of these lesions (21%) were calcified. In all cases surgery was performed via individually tailored posterior approaches. We evaluated the pre- and postoperative clinical status and the complication rate in a retrospective study. Nearly one half of the lesions (46.4%) were located at the three lowest thoracic segments. Clinical symptoms included back pain or radicular pain (77.8%), altered sensitivity (77.8%), weakness (40.7%), impaired gait (51.9%) or bladder dysfunction (22%). Costotransversectomy was performed in 8 patients, 1 lateral extracavitary approach, 2 foraminotomies, 15 transfacet and/or transpedicular approaches and 2 interlaminar approaches were used for removing the pathologies. After a mean follow-up of 38.6 months (3-100 months), complete normalization or reduction of local pain was recorded in 87% of the patients and of radicular pain in 70% of the cases, increased motor strength could be achieved in 55%, sensitivity improved in 76.2% and improvement of myelopathy was noted in 71.4%. Two patients suffered from postoperative impairment of sensory deficits, which in one case was discrete. The overall recovery rate within the modified JOA score was 39.5%. In 1 patient, two revisions were required because of instability and a persisting osteophyte, respectively. The rate of major complications was 7.1% (2/28). Surgical treatment of thoracic disc herniations via posterior approaches tailored to the individual patient produces satisfying results referring to clinical outcome. Posterior approaches remain a viable alternative for a large proportion of patients with symptomatic thoracic disc herniations. PMID:21533597
Posterior fossa calcifying pseudoneoplasm of the central nervous system.
Kerr, Edward E; Borys, Ewa; Bobinski, Matthew; Shahlaie, Kiarash
2013-04-01
Calcifying pseudoneoplasms of the neuraxis are rare, poorly understood masses that may arise throughout the CNS. Although these lesions are generally considered benign and noninfiltrative, reports exist that document growth of these masses on serial plain radiographs. The authors report a case of a posterior fossa calcifying pseudoneoplasm of the neuraxis demonstrating interval development of peritumoral edema on serial MRI. Their findings suggest that these lesions may sometimes behave in a more aggressive manner than commonly thought. PMID:23394341
Endoscopic technique for suturing posterior chamber intraocular lenses.
Leon, J A; Leon, C S; Aron-Rosa, D; Bremond-Gignac, D; Lassau, J P
2000-05-01
A challenge of the sutured posterior chamber intraocular lens (IOL) technique is to perform blind actions behind the iris. To avoid imprecise transscleral sutures and complications, we use an endoscopic procedure with 2 goals: to control the entry site of the needle penetration and of the haptic location. The endoscopic technique allows retroiris control during transscleral suturing and iridociliary IOL implantation. It is a safe, precise method that avoids the risks of blind procedures behind the iris. PMID:10831892
Posterior reversible encephalopathy syndrome (PRES) in critically ill obstetric patients
Giuseppe Servillo; Pasquale Striano; Salvatore Striano; Fabio Tortora; Patrizia Boccella; Edoardo De Robertis; Flavia Rossano; Francesco Briganti; Rosalba Tufano
2003-01-01
ObjectiveTo describe clinical, neuroradiological and evolutionary findings in obstetric patients with posterior reversible encephalopathy syndrome (PRES).DesignRetrospective case series.SettingUniversity intensive care unit (ICU).PatientsFour critically ill patients. Two patients experienced PRES in late postpartum without the classical pre-eclamptic signs. All patients showed impairment of consciousness and epileptic seizures; two of them presented cortical blindness and headache, too. True status epilepticus (SE) occurred
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.
Popliteal artery injury during posterior cruciate ligament reconstruction?
Cenni, Marcos Henrique Frauendorf; do Nascimento, Bruno Fajardo; Carneiro, Guilherme Galvão Barreto; de Andrade, Rodrigo Cristiano; Pinheiro Júnior, Lúcio Flávio Biondi; Nicolai, Oscar Pinheiro
2015-01-01
This study reports a case of popliteal artery injury during arthroscopic reconstruction of the posterior cruciate ligament. The evolution of the injury is described and comments are made regarding the anatomy of this artery and potential risks of this surgical technique. This study had the aims of alerting the medical community, especially knee surgeons, regarding a severe surgical complication and discussing the ways of preventing it. PMID:26229942
Cisplatin Neurotoxicity Presenting as Reversible Posterior Leukoencephalopathy Syndrome
Yasuhiro Ito; Yutaka Arahata; Yoji Goto; Masaaki Hirayama; Masaaki Nagamutsu; Takeshi Yasuda; Tsutomu Yanagi; Gen Sobue
Summary: Visual disturbance, hypertension, convulsions, and unconsciousness developed in a 70-year-old man after cisplatin chemotherapy and upper-limb amputation for os- teosarcoma. MR imaging revealed bilateral reversible ab- normalities in the occipital, parietal, and frontal white matter. Clinical and neuroradiologic features corre- sponded to reversible posterior leukoencephalopathy syn- drome (RPLS), which some immunosuppressive and che- motherapeutic drugs have been reported to
Posterior fossa arachnoid cysts and cerebellar tonsillar descent: short review.
Galarza, Marcelo; López-Guerrero, Antonio López; Martínez-Lage, Juan F
2010-07-01
The objective of this study was to analyze the association of cerebellar tonsillar descent and syringomyelia in patients with posterior fossa arachnoid cysts. We reviewed the medical records of ten patients (mean, age 33; range, 24-49 years) diagnosed with posterior fossa arachnoid cyst and tonsillar descent. Symptoms evolved over a mean of 12 months (range, 6 months to 3 years). Syringomyelia was present in six cases. Six patients underwent a suboccipital craniectomy, three cases underwent an additional C1 laminectomy, and a further case had a limited craniectomy and tonsillar reduction. Three patients were also treated for hydrocephalus: one with a ventriculoperitoneal shunt and two with endoscopic third ventriculostomy. Two patients had conservative treatment. The posterior fossa arachnoid cysts were located at the vermis-cisterna magna (n = 4), the cerebellar hemispheres (n = 2), the cerebellopontine angle (n = 3), and the quadrigeminal cistern (n = 1). A patient with achondroplasia showed features of platybasia. Associated malformations included craniofacial dysmorphism in a patient diagnosed of trichorhinophalangeal syndrome and a case with a primary temporal arachnoid cyst. After a mean follow-up of 2 years (range, 3 months to 5 years), four patients showed resolution of their neurological symptoms, and two exhibited persisting ocular findings. Headaches and nuchalgia improved in four cases and persisted in four. Syringomyelia was resolved in four patients and improved in two. Patients harboring a posterior fossa arachnoid cyst may evolve with acquired Chiari malformation and syringomyelia. Initial management should be directed to decompressing the foramen magnum and should include the resection of the arachnoid cyst's walls. A wait-and-see attitude can be implemented in selected cases. In our experience, hydrocephalus should be properly addressed before treating the arachnoid cyst. PMID:20480382
Posterior Fossa Meningiomas: Surgical Experience in 52 Cases
S. A. Cudlip; P. R. Wilkins; F. G. Johnston; A. J. Moore; H. T. Marsh; B. A. Bell
1998-01-01
Summary ?Background. Early reports of the surgical management of posterior cranial fossa meningiomas (PCFM) yielded poor results with high rates\\u000a of mortality and morbidity. With the advent of modern neuroimaging and microsurgical techniques the results of surgery have\\u000a improved markedly, but despite these advances removal of these lesions remains a challenge.\\u000a \\u000a ?Methods. The results of the surgical treatment of PCF meningiomas
Drug Delivery to the Posterior Eye Using Etched Microneedles
Geetha Mahadevan
2011-01-01
Sight-threatening diseases, such as age-related macular degeneration (AMD), affect the tissues of the posterior segment of the eye. Though modern classes of biomolecular based drugs are therapeutically useful, drug targeting for prolonged bioavailability to pathological sites within the eye is challenging. Current delivery approaches are invasive and lack control over drug release rates and tissue-specific localization. In this thesis, a
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
Posterior approach for sciatic aneurysm repair - technical note.
Cvetkovic, S; Koncar, I; Dragas, M; Ilic, N; Pejkic, S; Kostic, D; Davidovic, L
2014-10-01
Aneurysm of the persistent sciatic artery is a rare cause of limb ischemia, which is a challenge for both diagnosis and treatment. After successful diagnosis adequate treatment may require skills in open and endovascular surgery. We present a patient with the aneurysm of the persistent sciatic artery treated by bypass procedure with PTFE graft using posterior approach. We named this procedure "dorsal bypass". Detailed explanation of clinical presentation, diagnosis and the surgical procedure is given in this paper. PMID:24003007
Bilateral posterior hip dislocations with femoral head fractures.
Meislin, R J; Zuckerman, J D
1989-01-01
An unusual case of bilateral posterior fracture-dislocation of the hip (Pipkin Type IV) occurred in a 63-year-old man with Paget's disease of the pelvis. Other injuries included a displaced humeral shaft fracture and patellar ligament disruption. Bilateral cemented total hip arthroplasty was performed to avoid the need for prolonged immobilization. Postoperative low-dose irradiation was used because of the risk of heterotopic ossification. PMID:2600708
Foraminotomia cervical posterior en el tratamiento de conflictos foraminales
Campero, Álvaro; Barrera, Ramiro; Ajler, Pablo
2012-01-01
Introducción: La foraminomotima cervical posterior es un procedimiento utilizado para la descompresion radicular por via posterior y constituye una alternativa a la via clásica anterior. En este trabajo evaluamos nuestra serie de pacientes tratados por esta via. Método: Desde enero de 2008 a diciembre de 2011, 17 pacientes (18 foraminotomías) fueron operados por presentar cervicobraquialgia a causa de un conflicto foraminal, realizando un foraminotomía cervical posterior. Los pacientes fueron evaluados en el postoperatorio inmediato, al mes y a los 3 meses de la cirugía. Los parámetros para valorar los resultados fueron la Escala Análoga del Dolor (VAS), la Neck Disability Index y los criterios de Odom. Resultados: El dolor radicular por conflicto foraminal secundario a hernia de disco cervical fue el síntoma y la patología predominante. El nivel más afectado fue C5-C6. La resolución completa del dolor radicular se observó en casi todos los pacientes. La VAS preoperatoria en promedio fue de 8.8 (mínimo 8 – máximo 10), con una franca mejoría en todos los casos (0.4 en el último control). La media en la Neck Disability Index al inicio fue de 35.3 (mínimo 32 – máximo 45), con una evolución favorable en la evaluación final (0.6). Los Criterios de Odom para la evaluación de pacientes operados de columna cervical fueron satisfactorios con un promedio de 1.17. Se observaron complicaciones en 4 pacientes (23%), todas tuvieron una evolución favorable. No hubo infecciones, discitis ni empeoramiento de los síntomas preexistentes en ningún paciente. Conclusión: La foraminotomía cervical posterior es un procedimiento efectivo para el tratamiento del dolor radicular en los conflictos foraminales PMID:23596556
Translevator posterior intravaginal slingplasty: anatomical landmarks and safety margins
Stefan Smajda; Linda Vanormelingen; Giovanni Vandewalle; Willem Ombelet; Eric de Jonge; Piet Hinoul
2005-01-01
The posterior intravaginal sling is a new tension-free needle suspension technique. It is used for the treatment of middle compartment (vaginal vault or uterine) prolapse. The Prolene sling suspends the vagina at the upper border of level II support as described by DeLancey (Am J Obstet Gynecol 166:1717, 1992). Human cadaveric dissections were undertaken to explore the pertinent anatomy that
Probability workshop to be better in probability topic
NASA Astrophysics Data System (ADS)
Asmat, Aszila; Ujang, Suriyati; Wahid, Sharifah Norhuda Syed
2015-02-01
The purpose of the present study was to examine whether statistics anxiety and attitudes towards probability topic among students in higher education level have an effect on their performance. 62 fourth semester science students were given statistics anxiety questionnaires about their perception towards probability topic. Result indicated that students' performance in probability topic is not related to anxiety level, which means that the higher level in statistics anxiety will not cause lower score in probability topic performance. The study also revealed that motivated students gained from probability workshop ensure that their performance in probability topic shows a positive improvement compared before the workshop. In addition there exists a significance difference in students' performance between genders with better achievement among female students compared to male students. Thus, more initiatives in learning programs with different teaching approaches is needed to provide useful information in improving student learning outcome in higher learning institution.
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.
Tips for successful open surgical reconstruction of posterior urethral disruption injuries.
Gelman, Joel
2013-08-01
This article provides an overview of the open surgical management of posterior urethral disruption injuries. The discussion includes the evaluation of the patient before surgery with a focus on urethral imaging and details of posterior urethroplasty surgical technique. PMID:23905936
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
Evidence for extra radiation? Profile likelihood versus Bayesian posterior
Hamann, Jan
2012-03-01
A number of recent analyses of cosmological data have reported hints for the presence of extra radiation beyond the standard model expectation. In order to test the robustness of these claims under different methods of constructing parameter constraints, we perform a Bayesian posterior-based and a likelihood profile-based analysis of current data. We confirm the presence of a slight discrepancy between posterior- and profile-based constraints, with the marginalised posterior preferring higher values of the effective number of neutrino species N{sub eff}. This can be traced back to a volume effect occurring during the marginalisation process, and we demonstrate that the effect is related to the fact that cosmic microwave background (CMB) data constrain N{sub eff} only indirectly via the redshift of matter-radiation equality. Once present CMB data are combined with external information about, e.g., the Hubble parameter, the difference between the methods becomes small compared to the uncertainty of N{sub eff}. We conclude that the preference of precision cosmological data for excess radiation is 'real' and not an artifact of a specific choice of credible/confidence interval construction.
Aspects of treatment for posterior heel pain in young athletes
Elengard, Thomas; Karlsson, Jón; Silbernagel, Karin Grävare
2010-01-01
Posterior heel pain occurs in young athletes involved in running and jumping. Due to the pain, the child often limits his/her physical activity level, with a possible negative effect on health and well-being. Although numerous research studies have examined the cause and treatment of heel and Achilles tendon pain in adults, there are no randomized clinical trials on treatment in children and adolescents. Therefore, there is limited evidence for how to treat young athletes with this type of complaint. The purpose of this review was to analyze critically and summarize the literature in regards to the cause and treatment of posterior heel pain in young athletes. The various diagnoses and clinical presentations relating to posterior heel and Achilles tendon pain are discussed. The theory and mechanism behind various recommended treatment strategies are also reviewed in the context of use in the young athlete. In summary, it is important to perform a thorough evaluation of each young athlete with heel pain to determine the appropriate diagnosis and to treat the deficits found and allow for a gradual progression to training. However, the recommendations at this time are based on clinical experience and a few retrospective studies, so further well designed prospective studies with validated outcome measures are urgently needed for the young athlete. PMID:24198561
Posterior sagittal approach for resection of sacrococcygeal teratomas.
Jan, Iftikhar Ahmad; Khan, Ejaz A; Yasmeen, Nuzhat; Orakzai, Hazratullah; Saeed, Jahria
2011-05-01
The aim is to evaluate the ease of access, surgical trauma and cosmetic results of posterior sagittal approach for sacrococygeal teratomas (SCTs). From January 2002 to June 2010, we operated 19 cases of SCT exclusively through posterior sagittal approach. Patients were placed in knee chest position. An elliptical incision was made for the excision of the tumor. Care was taken to preserve all the muscles and other vital tissue in this area. Coccygectomy was performed in all patients. Closure was performed in layers. It was possible to resect all tumors from this approach and none of the patients required revision of the incision. Complete resection was possible in 17 patients while two had residual disease due to local extension. Minimal wound dehiscence was noted in four patients that healed spontaneously. It was possible to perform excision even in very large masses. Wound scar was satisfactory in most patients with preservation of gluteal folds. It is therefore concluded that posterior sagittal approach for SCT is feasible, with good access and cosmetic results. PMID:21344217
Evaluation of mandibular condyles in children with unilateral posterior crossbite.
Illipronti-Filho, Edson; Fantini, Solange Mongelli de; Chilvarquer, Israel
2015-01-01
The relationship of mandibular condyle dimensions and its association with unilateral posterior crossbite (UPXB) has been suggested in the literature. The purpose of this prospective study was to evaluate mandibular condyles on the left and right sides and between crossed and non-crossed sides in the sagittal and coronal planes, using cone-beam computed tomography (CBCT). Twenty CBCT images of 40 temporo mandibular joints (TMJs) in individuals in mixed dentition phase, which included 9 males (mean 7.9 years) and 11 females (mean 8.2 years), with unilateral posterior crossbite without premature contacts and functional mandibular shifts and with transverse maxillary deficiency. The criteria for sample exclusion included the presence of painful symptoms, facial trauma history, systemic diseases such as juvenile rheumatoid arthritis, mouth opening limitation (< 40 mm), congenital or genetic anomalies, and skeletal asymmetries that may result in TMJ disorders. Dimensional measurements of the condyles between the right and left sides and crossed and non-crossed sides in sagittal and coronal view were made. There was no significant difference between the measurements of the crossed and non-crossed sides in both sagittal and coronal view. These findings suggest that the presence of unilateral posterior crossbite in children with UPXB did not result in changes between the mandibular condyles in the right and left sides or between the crossed and non-crossed sides in the coronal or sagittal plane. PMID:25760067
Automated measurement of anterior and posterior acetabular sector angles
NASA Astrophysics Data System (ADS)
Ibragimov, Bulat; Likar, Boštjan; Pernuš, Franjo; Vrtovec, Tomaž
2012-03-01
In this paper, we propose a segmentation algorithm by which anatomical landmarks on the pelvis are extracted from computed tomography (CT) images. The landmarks are used to automatically define the anterior (AASA) and posterior acetabular sector angles (PASA) describing the degree of hip misalignment. The center of each femoral head is obtained by searching for the point at which most intensity gradient vectors defined at edge points intersect. The radius of each femoral head is computed by finding the sphere, positioned at the center of the femoral head, for which the normalized sum of gradient vector magnitudes on the sphere surface is maximal. The anterior and posterior corners of each acetabulum are searched for on a curve representing the acetabulum and defined by dynamic programming. The femoral head centers and anterior and posterior corners are used to calculate the AASA and PASA. The algorithm was applied to CT images of 120 normal subjects and the results were compared to ground truth values obtained by manual segmentation. The mean absolute difference (+/- standard deviation) between the obtained and ground truth values was 1.3 +/- 0.3 mm for the femoral head centers and 2.1 +/- 1.3 degrees for the acetabular angles.
Motion of threaded cages in posterior lumbar interbody fusion.
Pitzen, T; Geisler, F H; Matthis, D; Müller-Storz, H; Steudel, W I
2000-12-01
A high rate of pseudarthrosis and a high overall rate of implant migration requiring surgical revision has been reported following posterior lumbar interbody fusion using BAK threaded cages. The high rate of both pseudarthrosis and implant migration may be due to poor fixation of the implant. The purpose of this study was to analyse the motion of threaded cages in posterior lumbar interbody fusion. Six cadaveric human lumbar spine segments (three L2/3 and three L4/5 segments) were prepared for biomechanical testing. The segments were tested, without preload, under forces of axial compression (600 N), torsion (25 Nm) and shearing force (250 N). The tests were performed first with the segments in an intact state, and subsequently following instrumented stabilisation with two BAK cages via a posterior approach. These results were compared with those of a finite element model simulating the effects of identical forces on the segments with constructs. As the results were comparable, the finite element model was used for analysing the motion of BAK cages within the disc space. Motion of the implants was not seen in compression. In torsion, a rolling motion was noted, with a range of motion of 10.6 degrees around the central axis of the implant when left/right torsion (25 Nm) was applied. The way the implants move within the segment may be due to their special shape: the thread of the implants can not prevent the BAK cages rolling within the disc space. PMID:11189929
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.
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...
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
Ultrahighly accurate 3D profilometer
NASA Astrophysics Data System (ADS)
Tsutsumi, Hideki; Yoshizumi, Keiichi; Takeuchi, Hiroyuki
2005-02-01
We have developed an Ultrahigh-Accurate 3-D Profilometer (UA3P), which, using a new, in-house-developed atomic force probe, has an accuracy of 10 nm. It is capable of measuring corners as small as 2 micro meter in radius and can cover an area up to 400 x 400 x 90 (mm), providing a powerful boost to nano-level processing. A commercial product was introduced in 1994. Examples of the key components made possible by this technology include aspherical lenses (used for a Blu-ray Disc device, a next-generation DVD, digital cameras, cellular phones, optical communications), free form lenses (used for frennel lens common to CD and DVD, laser printer lens, multi focus glass lens, cubic phase plate to extend depth of focus), gigabit semiconductor wafers, hard discs, air conditioner scroll vanes, DVC cylinders. The premiere ultra high-precision three-dimensional profilometer delivers superb performance using a variety of micro-measurements for a wide range of applications.
Classifier calibration using splined empirical probabilities in clinical risk prediction.
Gaudoin, René; Montana, Giovanni; Jones, Simon; Aylin, Paul; Bottle, Alex
2015-06-01
The aims of supervised machine learning (ML) applications fall into three broad categories: classification, ranking, and calibration/probability estimation. Many ML methods and evaluation techniques relate to the first two. Nevertheless, there are many applications where having an accurate probability estimate is of great importance. Deriving accurate probabilities from the output of a ML method is therefore an active area of research, resulting in several methods to turn a ranking into class probability estimates. In this manuscript we present a method, splined empirical probabilities, based on the receiver operating characteristic (ROC) to complement existing algorithms such as isotonic regression. Unlike most other methods it works with a cumulative quantity, the ROC curve, and as such can be tagged onto an ROC analysis with minor effort. On a diverse set of measures of the quality of probability estimates (Hosmer-Lemeshow, Kullback-Leibler divergence, differences in the cumulative distribution function) using simulated and real health care data, our approach compares favourably with the standard calibration method, the pool adjacent violators algorithm used to perform isotonic regression. PMID:24557734
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
Posterior corneal curvature changes following Refractive Small Incision Lenticule Extraction
Ganesh, Sri; Patel, Utsav; Brar, Sheetal
2015-01-01
Purpose To compare the posterior corneal curvature changes, in terms of corneal power and asphercity, following Refractive Small Incision Lenticule Extraction (ReLEx SMILE) procedure for low, moderate, and high myopia. Methods This retrospective, non randomized, comparative, interventional trial; included 52 eyes of 26 patients, divided in three groups: low myopia (myopia ?3 D [diopters] spherical equivalent [SE]), moderate myopia (myopia >3 D and <6 D SE), and high myopia (myopia ?6 D SE). All patients were treated for myopia and myopic astigmatism using ReLEx SMILE. The eyes were examined pre-operatively and 3 months post-operatively using SCHWIND SIRIUS, a three-dimensional rotating Scheimpflug camera with a Placido disc topographer to assess corneal changes with regard to keratometric power and asphericity of the cornea. Results A statistically significant increase in mean keratometric power in the 3, 5, and 7 mm zones of the posterior corneal surface compared with its pre-ReLEx SMILE value was detected after 3 months in the moderate myopia group (pre-operative [pre-op] ?6.14±0.23, post-operative [post-op] ?6.29±0.22, P<0.001) and high myopia group (pre-op ?6.19±0.16, post-op ?6.4±0.18, P<0.001), but there was no significant change in keratometric power of the posterior surface in the low myopia group (pre-op ?5.87±0.17, post-op ?6.06±0.29, P=0.143). Asphericity (Q-value) of the posterior surface changed significantly (P<0.001) after ReLEx SMILE in the moderate myopia group in the 3, 5, and 7 mm zones, and in the high myopia group in the 3 and 7 mm zones; but there was no significant change in the Q-value in the low myopia group in all three zones (pre-op 0.23±0.43, post-op ?0.40±0.71, P=0.170), and in the high myopia group in the 5 mm zone (P=0.228). Conclusion ReLEx SMILE causes significant changes in posterior corneal keratometric power and asphericity in moderate and high myopia, but the effect is subtle and insignificant in low myopia. PMID:26229428
Pars Plana Vitrectomy in Eyes Containing a Treated Posterior Uveal Melanoma
Foster, William
into the posterior segment or manipulation of the vitreous in proximity to the melanoma. Repair of rhegmatogenousPars Plana Vitrectomy in Eyes Containing a Treated Posterior Uveal Melanoma WILLIAM J. FOSTER, MD PURPOSE: To determine the safety of pars plana vitrec- tomy in eyes containing a treated posterior uveal
Nonanatomic Location of the Posterior Horn of a Medial Meniscal Autograft
Hull, Maury
of Mechanical Engineering, University of California, Davis, California ABSTRACT Nonanatomic placement with the posterior horn tunnel in non- anatomic locations (5 mm medial and 5 mm posterior) and in the anatomic of the centroid of contact area were compared. Placement of the posterior horn tunnel in the nonana- tomic medial
Marvin E. Myles; Donna M. Neumann; James M. Hill
2005-01-01
Age-related macular degeneration, diabetic retinopathy, posterior uveitis, and retinitis due to glaucoma are leading causes of vision loss in the United States and other developed countries. Because these diseases are located in the posterior segment of the eye, topical application of ophthalmic medicines is of limited benefit, since topically applied drugs rarely reach therapeutic levels in the affected posterior tissues
Morphology Parameters for Mirror Posterior Communicating Artery Aneurysm Rupture Risk Assessment.
Jiang, Hao; Shen, Jian; Weng, Yu-Xiang; Pan, Jian-Wei; Yu, Jian-Bo; Wan, Zi-Ang; Zhan, Renya
2015-01-01
Recent studies have shown that posterior communicating artery (PComA) aneurysms are more likely to rupture. However, surgical intervention for PComA aneurysms may be associated with increased treatment-related morbidity rate. Therefore, it is meaningful to investigate the factors related to PComA aneurysm rupture. The purpose of this study was to identify morphological parameters that significantly correlate with PComA aneurysm rupture. We divided 14 pairs of mirror posterior communicating artery aneurysms (PComA-MANs) into ruptured and unruptured groups. Computed tomography angiography (CTA) imaging was evaluated with three-dimensional (3D) Slicer to generate models of the aneurysms and surrounding vasculature. Nine morphological parameters [size, height, width, neck width, aspect ratio (AR), bottleneck factor (BNF), height/width ratio (H/W), size ratio (SR), and bleb formation] were examined in the two groups for significance with respect to rupture. By contrast, statistically significant differences were found in ruptured and unruptured group for size, AR, BNF, SR, and bleb formation (P < 0.05). Parameters that had no significant differences between the two groups were height (P = 0.103), width (P = 0.078), neck width (P = 0.808), and H/W (P = 0.417). We conclude that MANs may be a useful model for the morphological analysis of intracranial aneurysm rupture. Larger size, higher AR, BNF, SR, and bleb formation may be related to rupture of PComA aneurysms. Larger sample studies minimizing the interference from patient-related factors and aneurysm type were expected for acquiring more accurate assessment of the relationship between these parameters and PComA aneurysm rupture. PMID:26041624
Probability Surveys, Conditional Probability, and Ecological Risk Assessment
We show that probability-based environmental resource monitoring programs, such as the U.S. Environmental Protection Agency’s (U.S. EPA) Environmental Monitoring and Assessment Program, and conditional probability analysis can serve as a basis for estimating ecological risk over ...
PROBABILITY SURVEYS, CONDITIONAL PROBABILITIES, AND ECOLOGICAL RISK ASSESSMENT
We show that probability-based environmental resource monitoring programs, such as U.S. Environmental Protection Agency's (U.S. EPA) Environmental Monitoring and Asscssment Program EMAP) can be analyzed with a conditional probability analysis (CPA) to conduct quantitative probabi...
Facilitating normative judgments of conditional probability: frequency or nested sets?
Yamagishi, Kimihiko
2003-01-01
Recent probability judgment research contrasts two opposing views. Some theorists have emphasized the role of frequency representations in facilitating probabilistic correctness; opponents have noted that visualizing the probabilistic structure of the task sufficiently facilitates normative reasoning. In the current experiment, the following conditional probability task, an isomorph of the "Problem of Three Prisoners" was tested. "A factory manufactures artificial gemstones. Each gemstone has a 1/3 chance of being blurred, a 1/3 chance of being cracked, and a 1/3 chance of being clear. An inspection machine removes all cracked gemstones, and retains all clear gemstones. However, the machine removes 1/2 of the blurred gemstones. What is the chance that a gemstone is blurred after the inspection?" A 2 x 2 design was administered. The first variable was the use of frequency instruction. The second manipulation was the use of a roulette-wheel diagram that illustrated a "nested-sets" relationship between the prior and the posterior probabilities. Results from two experiments showed that frequency alone had modest effects, while the nested-sets instruction achieved a superior facilitation of normative reasoning. The third experiment compared the roulette-wheel diagram to tree diagrams that also showed the nested-sets relationship. The roulette-wheel diagram outperformed the tree diagrams in facilitation of probabilistic reasoning. Implications for understanding the nature of intuitive probability judgments are discussed. PMID:12693194
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.
Problems with Objective Probability for Conditionals What Bennett Means by Objective Probability
Fitelson, Branden
Problems with Objective Probability for Conditionals What Bennett Means by Objective Probability Objective probability is any sort of probability which demands inter- subjective agreement. Bennett distinguishes two types of objective probability. Absolute objective probability: This is the sort
Accurate orientation relationships between ferrite and cementite in pearlite
Zhang, M.X.; Kelly, P.M.
1997-12-15
In most previous work, the interlamellar interface between pearlitic ferrite and cementite is considered to have a low energy and dislocations have been observed at the interfacial boundary, in both plain carbon steels and high manganese steels. Here, four new orientation relationships (ORs) between pearlitic ferrite and cementite have been determined using the more accurate CBKLDP technique. In eutectoid steel the pearlite obeys the New-2, New-3 and New-4 ORs; in hypoeutectoid steel only the Isaichev OR is observed; in hypereutectoid steel the New-5 OR is followed. The two widely accepted ORs, the Pitsch-Petch OR and the Bagaryatskii OR have never been observed. They probably do not exist.
Idiopathic bone cavity on the posterior buccal surface of the mandible.
Kocsis, G S; Marcsik, A; Mann, R W
1992-01-01
A cavity on the posterior buccal surface of four dry mandibles (n = 8282) is reported. The shape, size, unilaterality, and sex distribution of this phenomenon are similar to anterior and posterior idiopathic bone cavities (i.e., defects) on the lingual cortex. Posterior buccal mandibular defects differ from posterior lingual cavities in their unilateral occurrence and age distribution. The differential diagnosis for posterior buccal mandibular defects includes an anatomic variant, an aneurysmal erosion, erosion by a lymphoid nodule, and a neural neoplasm. PMID:1603551
Understanding Students' Beliefs about Probability.
ERIC Educational Resources Information Center
Konold, Clifford
The concept of probability is not an easy concept for high school and college students to understand. This paper identifies and analyzes the students' alternative frameworks from the viewpoint of constructivism. There are various interpretations of probability through mathematical history: classical, frequentist, and subjectivist interpretation.…
Landau-Zener Probability Reviewed
C. Valencia; D. E. Jaramillo
2008-06-06
We examine the survival probability for neutrino propagation through matter with variable density. We present a new method to calculate the level-crossing probability that differs from Landau's method by constant factor, which is relevant in the interpretation of neutrino flux from supernova explosion.
Improving Aggregated Forecasts of Probability
Osherson, Daniel
include "President Obama will be re- elected in 2012", "Obama will be re-elected if the U.S. unemploy, a user might be asked questions about simple events such as "What is the probability that Obama wins Indiana?" and also questions about complex events like "What is the probability that Obama wins Vermont
Minimizing the probable maximum flood
Woodbury, M.S.; Pansic, N. ); Eberlein, D.T. )
1994-06-01
This article examines Wisconsin Electric Power Company's efforts to determine an economical way to comply with Federal Energy Regulatory Commission requirements at two hydroelectric developments on the Michigamme River. Their efforts included refinement of the area's probable maximum flood model based, in part, on a newly developed probable maximum precipitation estimate.
Training Teachers to Teach Probability
ERIC Educational Resources Information Center
Batanero, Carmen; Godino, Juan D.; Roa, Rafael
2004-01-01
In this paper we analyze the reasons why the teaching of probability is difficult for mathematics teachers, describe the contents needed in the didactical preparation of teachers to teach probability and analyze some examples of activities to carry out this training. These activities take into account the experience at the University of Granada,…
THE DISCOVERY OF ALGORITHMIC PROBABILITY
Solomonoff, Ray
THE DISCOVERY OF ALGORITHMIC PROBABILITY Ray J. Solomono# # Royal Holloway, University of London will describe a voyage of discovery --- the discovery of Algorithmic Probability. But before I describe, the motivation is discovery itself --- the joy of ``going where no one has gone before'' --- the excitement
THE DISCOVERY OF ALGORITHMIC PROBABILITY
Solomonoff, Ray
THE DISCOVERY OF ALGORITHMIC PROBABILITY Ray J. Solomonoff Royal Holloway, University of London will describe a voyage of discovery -- the discovery of Algorithmic Probability. But before I describe, the motivation is discovery itself -- the joy of "going where no one has gone before" -- the excitement
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.
Probability theory and its models
Paul Humphreys
2008-01-01
This paper argues for the status of formal probability theory as a mathematical, rather than a scientific, theory. David Freedman and Philip Stark's concept of model based probabilities is examined and is used as a bridge between the formal theory and applications.
Exercises in Probability Second Edition
Chaumont, Loïc
. Probability, by Rick Durrett 33. Stochastic Processes, by Richard F. Bass 34. Structured Regression 20. Random Graph Dynamics, by Rick Durrett 21. Networks, by Peter Whittle 22. SaddlepointExercises in Probability Second Edition Derived from extensive teaching experience in Paris
The Probabilities of Conditionals Revisited
ERIC Educational Resources Information Center
Douven, Igor; Verbrugge, Sara
2013-01-01
According to what is now commonly referred to as "the Equation" in the literature on indicative conditionals, the probability of any indicative conditional equals the probability of its consequent of the conditional given the antecedent of the conditional. Philosophers widely agree in their assessment that the triviality arguments of…
Capture probabilities for secondary resonances
NASA Technical Reports Server (NTRS)
Malhotra, Renu
1990-01-01
A perturbed pendulum model is used to analyze secondary resonances, and it is shown that a self-similarity between secondary and primary resonances exists. Henrard's (1982) theory is used to obtain formulas for the capture probability into secondary resonances. The tidal evolution of Miranda and Umbriel is considered as an example, and significant probabilities of capture into secondary resonances are found.
Ideas that Lead to Probability
NSDL National Science Digital Library
2011-01-19
This lesson is designed to introduce students to random numbers and fairness as a precursor to learning about probability. The lesson provides links to discussions and activities related to probability and fairness 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 this one.
Total Probability and Bayes' Theorem
Vickers, James
Total Probability and Bayes' Theorem 35.4 Introduction When the ideas of probability are applied known as Bayesian Statistics here, it is worth noting that Bayes' Theorem is the basis of this branch- ple space' understand the special case of Bayes' Theorem arising when a sample space is partitioned
Probability and complex quantum trajectories
John, Moncy V. [Department of Physics, St. Thomas College, Kozhencherry, Pathanamthitta, Kerala 689 641 (India)], E-mail: moneyjohn@yahoo.co.uk
2009-01-15
It is shown that in the complex trajectory representation of quantum mechanics, the Born's {psi}*{psi} probability density can be obtained from the imaginary part of the velocity field of particles on the real axis. Extending this probability axiom to the complex plane, we first attempt to find a probability density by solving an appropriate conservation equation. The characteristic curves of this conservation equation are found to be the same as the complex paths of particles in the new representation. The boundary condition in this case is that the extended probability density should agree with the quantum probability rule along the real line. For the simple, time-independent, one-dimensional problems worked out here, we find that a conserved probability density can be derived from the velocity field of particles, except in regions where the trajectories were previously suspected to be nonviable. An alternative method to find this probability density in terms of a trajectory integral, which is easier to implement on a computer and useful for single particle solutions, is also presented. Most importantly, we show, by using the complex extension of Schrodinger equation, that the desired conservation equation can be derived from this definition of probability density.
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
Posterior trochanteric osteotomy in acetabular fractures for 32 cases.
Niu, Yunfei; An, Xiaofei; Xu, Shuogui; Wu, Dajiang; Zhang, Chuncai; Li, Ming
2014-11-01
The aim of this study is to explore the method and clinical outcome of posterior trochanteric osteotomy in acetabular fractures. From January 2000 to January 2008, 32 cases of acetabular fractures involving the dome of acetabulum underwent posterior trochanteric osteotomy for a better exposure and internal fixation with acetabular tridimensional memory fixation system. 28 cases (16 men and 12 women, mean age 39.9 years, range 16-73 years) were followed up with an average of 48.9 months (range of 19-95 months) and four were lost during follow up. Of 28 cases, 19 were fresh fractures and 9 were old fractures. The reduction was evaluated with Matta criteria. Clinical evaluation was based on modified Merle d'Aubigne and Postel scoring. Motor strength of the abductors was evaluated according to the Medical Research Council grading system. Ectopic ossification was classified according to Brooker criteria. Anatomical reduction was achieved in 17 cases and satisfied reduction in 10 patients. Poor reduction happened in an old fracture. All acetabular fractures got a direct bone union and no displacement and deep infection occurred. All osteotomies healed within 3.5 months without any nonunion, proximal migration of the greater trochanter, loosing or broken of instrumentation, and deep infection. Two superficial infections were healed with a regular dressing. Two patients underwent removal of implants from greater trochanter because of irritation. The strength of the abductors was of Grade 3/5 in two patients, Grade 4/5 in five patients, and normal in the rest. Clinical scoring was excellent to good in 84 %. Ectopic ossification occurred in five patients, grade 1 in two patients, grade 2 in two, and grade 3 in one. But function of hip joint was not seriously affected. Posterior trochanteric osteotomy can provide an adequate exposure of the dome of acetabulum without the associated complications like nonunion, proximal replacement, and weak of the abductors which often occur with standard oblique osteotomy. PMID:25113643
Posterior-inferior glenoid rim shapes by MR imaging.
Mulligan, M E; Pontius, C S
2005-11-01
Our purpose was to try to apply a CT classification of glenoid rim shapes to MR images and to determine the reliability of the subsequent MR classification by testing observer variability. Shoulder MR imaging exams of 54 consecutive patients were reviewed retrospectively by two musculoskeletal radiologists independently. Posterior-inferior glenoid rim shape was categorized, based on reported CT criteria, as triangle, "lazy-J" or "delta" using the most caudal MR section that unequivocally showed articular cartilage. The same studies were reviewed again one month later to test interobserver and intraobserver variability. Final determination of glenoid rim type was made by consensus. There were 31 males and 23 females with an average age of 42 years, range 14-75 years. Forty-one patients were referred for evaluation of nonspecific shoulder pain, 9 for suspected rotator cuff tear and 4 for instability. The most common shape was "lazy-J" with 32 patients (59%) having this type. The least common was delta shape, with 7 patients (13%) having this form. Fifteen patients (28%) had a normal triangle shape. There was significant interobserver variability in determining the shape of the glenoid rim with 17/54 (31%) discordant readings. For the "lazy-J" shape, the kappa value was .02, for the "delta" type, kappa value was .60 and for the triangle shape, kappa was .32. Intraobserver variability was 35% for radiologist A and 28% for radiologist B. Kappa values for intraobserver variability ranged from .53 to .85. Four patients had posterior instability, 3 were judged to have normal triangular inferior glenoid rims and 1 a "lazy J" type by Radiologist A. Radiologist B judged 2 of the instability patients as normal triangular and 2 as "lazy J". A CT classification of posterior-inferior glenoid rim shapes can be applied using MR imaging, however, there is significant observer variability that limits the applicability of this classification scheme with MR imaging. PMID:16200386
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
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
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
Intractable Hiccups Due to Posterior Inferior Cerebellar Artery Aneurysm
Chehab, Monzer; Noujaim, Samir; Qahwash, Omar; Mezwa, Duane; Roy, Anindya
2015-01-01
This is the third reported case of a posterior inferior cerebellar artery (PICA) aneurysm presenting as intractable hiccups (IH). A previously healthy 29-year-old woman was admitted with a 2-week history of hiccups occurring >100 times per minute. Symptoms persisted despite numerous noninvasive therapies. Magnetic resonance imaging and magnetic resonance angiogram of the brain showed a left PICA aneurysm that was confirmed by catheter angiography. Symptoms resolved following suboccipital craniotomy and resection. Although rare, PICA aneurysm is a potentially curable cause of IH. PMID:26251787
Intractable Hiccups Due to Posterior Inferior Cerebellar Artery Aneurysm.
Chehab, Monzer; Noujaim, Samir; Qahwash, Omar; Mezwa, Duane; Roy, Anindya
2015-07-01
This is the third reported case of a posterior inferior cerebellar artery (PICA) aneurysm presenting as intractable hiccups (IH). A previously healthy 29-year-old woman was admitted with a 2-week history of hiccups occurring >100 times per minute. Symptoms persisted despite numerous noninvasive therapies. Magnetic resonance imaging and magnetic resonance angiogram of the brain showed a left PICA aneurysm that was confirmed by catheter angiography. Symptoms resolved following suboccipital craniotomy and resection. Although rare, PICA aneurysm is a potentially curable cause of IH. PMID:26251787
Posterior reversible encephalopathy syndrome in a patient of organophosphate poisoning
Phatake, Rajesh; Desai, Sameer; Lodaya, Manikanth; Deshpande, Shrinivas; Tankasali, Nagaraj
2014-01-01
A 32-year-old male presented with a history of consuming some organophosphorous compound with suicidal intention. He was treated with atropine, pralidoxime, ventilator support. During stay patient had persistent irritability, tachycardiaand hypertension despite sedation and labetalol infusion. He developed headache, visual blurring hemiparesis and focal seizures. Magnetic resonance imaging of the brain revealed multifocal hyperintensities mainly in subcortical areas of parietal and occipital regions in T2-weighted images, with increased values of Apparent Diffusion Coefficient, suggesting posterior reversible encephalopathy syndrome (PRES). The possibilities of PRES caused by organophosphorous poisoning either due to hypertension caused by autonomic deregulation or direct neurological toxicity has been discussed. PMID:24872658
Prodromal Posterior Cortical Atrophy: Clinical, Neuropsychological and Radiological Correlation
Chan, Lung Tat Andrew; Lynch, Whitney; De May, Mary; Horton, Jonathan C.; Miller, Bruce L.
2015-01-01
We present longitudinal clinical, cognitive and neuroimaging data from a 63-year-old woman who enrolled in research as a normal control and evolved posterior cortical atrophy (PCA) over five year follow-up. At baseline she reported only subtle difficulty driving and performed normally on cognitive tests, but already demonstrated atrophy in left visual association cortex. With follow-up she developed insidiously progressive visuospatial and visuoperceptual deficits, correlating with progressive atrophy in bilateral visual areas. Amyloid PET was positive. This case tracks the evolution of PCA from the prodromal stage, and illustrates challenges to early diagnosis as well as the utility of imaging biomarkers. PMID:24308559
Minimally symptomatic posterior reversible encephalopathy in Guillain-Barré syndrome
Piccolo, Giovanni; Borutti, Giuseppina; Franciotta, Diego; Arbasino, Carla; Dallocchio, Carlo; Camana, Claudia; Gola, Giada; Egitto, Maria Grazia
2015-01-01
Summary Posterior reversible encephalopathy syndrome (PRES) is a rare occurrence in patients with Guillain-Barré syndrome (GBS). Two patients with neuroradiological evidence of PRES without central nervous system (CNS) symptoms were recently reported. We present the case of a GBS patient with minimal CNS symptoms and magnetic resonance imaging findings consistent with PRES. PRES in GBS might be an underestimated condition. It should be suspected in GBS patients in the presence of even mild CNS symptoms. A timely PRES diagnosis along with early correction of autonomic system dysfunction in GBS patients is recommended to prevent possible dangerous CNS complications. PMID:26214029
Prodromal posterior cortical atrophy: clinical, neuropsychological, and radiological correlation.
Chan, Lung Tat Andrew; Lynch, Whitney; De May, Mary; Horton, Jonathan C; Miller, Bruce L; Rabinovici, Gil D
2015-02-01
We present longitudinal clinical, cognitive, and neuroimaging data from a 63-year-old woman who enrolled in research as a normal control and evolved posterior cortical atrophy (PCA) over 5 year follow-up. At baseline she reported only subtle difficulty driving and performed normally on cognitive tests, but already demonstrated atrophy in left visual association cortex. With follow-up she developed insidiously progressive visuospatial and visuoperceptual deficits, correlating with progressive atrophy in bilateral visual areas. Amyloid PET was positive. This case tracks the evolution of PCA from the prodromal stage, and illustrates challenges to early diagnosis as well as the utility of imaging biomarkers. PMID:24308559
[Should the posterior approach to the rectum be forgotten?].
Groebli, Y; Tschantz, P
1994-04-01
The posterior approach to the low and mid-rectum is a good and anatomical way to treat high fistulas' problems, perirectal tumors and villous adenoma. It is also possible to treat by this method some rectal adenocarcinomas in special situations and in high-risk patients. A good evaluation of the disease if possible by rectal endosonography, has to be done. Coccygectomy is necessary but the transsphincteric route is not mandatory and has never been used here. 9 cases are reported with relatively good results. PMID:8034540
Seizure induced polytrauma; not just posterior dislocation of the shoulder.
Gill, James Ritchie; Murphy, Colin G; Quansah, Benjamin; Carrothers, Andrew D
2015-01-01
A 61-year-old woman sustained multiple fractures secondary to the tonic clonic muscular contractions of a seizure. Her injuries included: bilateral proximal humerus posterior fracture dislocations, manubrium fracture, unstable sixth thoracic vertebrae crush fracture, bilateral acetabular fractures and a left femoral neck fracture. Seizures are a rare but recognised cause of fracture. Patients with osteoporosis are more susceptible to more serious fractures to long bones, spine and pelvis. The lack of history of high-energy trauma can lead to a delay in diagnosis. Rarely, the combination and magnitude of these injuries can be life-threatening. PMID:26307650
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,
Posterior cingulate cortex: adapting behavior to a changing world.
Pearson, John M; Heilbronner, Sarah R; Barack, David L; Hayden, Benjamin Y; Platt, Michael L
2011-04-01
When has the world changed enough to warrant a new approach? The answer depends on current needs, behavioral flexibility and prior knowledge about the environment. Formal approaches solve the problem by integrating the recent history of rewards, errors, uncertainty and context via Bayesian inference to detect changes in the world and alter behavioral policy. Neuronal activity in posterior cingulate cortex - a key node in the default network - is known to vary with learning, memory, reward and task engagement. We propose that these modulations reflect the underlying process of change detection and motivate subsequent shifts in behavior. PMID:21420893
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
Giant liposarcoma of the posterior mediastinum and retroperitoneum.
Taki, Katsunobu; Watanabe, Masayuki; Iwagami, Shiro; Nagai, Yohei; Iwatsuki, Masaaki; Ishimoto, Takatsugu; Baba, Yoshifumi; Miyamoto, Yuji; Baba, Hideo
2011-01-01
A 39-year-old Japanese man has been complaining of chest pain for 3 months and a CT revealed a huge tumour in the posterior mediastinum and retroperitoneum. The mediastinal tumour was continuous with the retroperitoneal one through the oesophageal hiatus and the lower oesophagus was completely surrounded by the tumour. MRI suggested lipogenic tumour. Resection of the tumour with oesophagectomy was performed through bilateral thoracotomy and laparotomy. Pathological examination revealed well-differentiated liposarcoma which was completely resected. The patient has been alive without recurrence for 14 months after surgery. PMID:22688481
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
Probable Inference and Quantum Mechanics
Grandy, W. T. Jr. [Department of Physics and Astronomy, University of Wyoming, Laramie, WY 82070 (United States)
2009-12-08
In its current very successful interpretation the quantum theory is fundamentally statistical in nature. Although commonly viewed as a probability amplitude whose (complex) square is a probability, the wavefunction or state vector continues to defy consensus as to its exact meaning, primarily because it is not a physical observable. Rather than approach this problem directly, it is suggested that it is first necessary to clarify the precise role of probability theory in quantum mechanics, either as applied to, or as an intrinsic part of the quantum theory. When all is said and done the unsurprising conclusion is that quantum mechanics does not constitute a logic and probability unto itself, but adheres to the long-established rules of classical probability theory while providing a means within itself for calculating the relevant probabilities. In addition, the wavefunction is seen to be a description of the quantum state assigned by an observer based on definite information, such that the same state must be assigned by any other observer based on the same information, in much the same way that probabilities are assigned.
Electrofishing capture probability of smallmouth bass in streams
Dauwalter, D.C.; Fisher, W.L.
2007-01-01
Abundance estimation is an integral part of understanding the ecology and advancing the management of fish populations and communities. Mark-recapture and removal methods are commonly used to estimate the abundance of stream fishes. Alternatively, abundance can be estimated by dividing the number of individuals sampled by the probability of capture. We conducted a mark-recapture study and used multiple repeated-measures logistic regression to determine the influence of fish size, sampling procedures, and stream habitat variables on the cumulative capture probability for smallmouth bass Micropterus dolomieu in two eastern Oklahoma streams. The predicted capture probability was used to adjust the number of individuals sampled to obtain abundance estimates. The observed capture probabilities were higher for larger fish and decreased with successive electrofishing passes for larger fish only. Model selection suggested that the number of electrofishing passes, fish length, and mean thalweg depth affected capture probabilities the most; there was little evidence for any effect of electrofishing power density and woody debris density on capture probability. Leave-one-out cross validation showed that the cumulative capture probability model predicts smallmouth abundance accurately. ?? Copyright by the American Fisheries Society 2007.
Full arthroscopic inlay reconstruction of posterior cruciate ligament.
Mariani, Pier Paolo; Margheritini, Fabrizio
2006-11-01
We report a full arthroscopic inlay reconstruction technique to avoid the morbidity of traditional open inlay procedure. With the transeptal approach a trough is created arthroscopically at the anatomical tibial insertion of the PCL, which must fit with the patellar bone block of a quadriceps tendon autograft. The bone plug is harvested with two nonabsorbable sutures, each end of which is passed through two holes from the cortical to the cancellous side. The graft is introduced into the knee joint from the posteromedial portal using two traction sutures passed previously through two transtibial tunnels exiting at the middle of the trough. Tibial graft fixation is achieved using the sutures knotted at the anterior aspect of the tibial cortex. Arthroscopic inlay procedure may be a rational surgical alternative because it reduces the crucial steps of an open inlay procedure, such as extensive exposure of the posterior capsule, the need of position change with risk of contamination, longer surgical time, and the risk of bone block fracture if an autograft is harvested. The arthroscopic procedure may also be performed also when hardware presence of previous surgery limits use of the open technique. We initially limited use of this technique to patients: (1) undergoing PCL revision surgery, (2) having hardware from previous tibial surgery, and (3) presenting a PCL lesion following posterior dislocation with previous vascular surgery. The results have been good, and we are now also using this technique for primary PCL reconstruction with favorable results. PMID:16960740
[Therapeutic approach in a fetus with posterior urethral valves].
Albert, A; Morales, L; Puerto, B; Borrell, A; Sancho, M A; Gonzálezl Linas, L F
1993-07-01
A pregnant woman was diagnosed with fetal uropathy at 18 weeks gestation. A thorough examination revealed bilateral hydronephrosis, megacystis with bladder neck and posterior urethral dilatation, normohydramnios, normal echocardiography and normal male karyotype. From the 20th week on she developed a progressive oligohydramnios, and the left kidney became hyperechogenic. Fetal urine analysis at week 21 showed hypotonic urine in both renal pelvises, and a beta 2 microglobulin of 8.5 mg/l. on the right side and 18 mg/l. on the left one, suggesting some degree of function on the right kidney. A vesico-amniotic shunt was placed at week 22, which was ineffective, and another shunt was placed two weeks later. Twenty-four hours later the bladder size decreased, but amniotic fluid did not increase and a great amount of ascitis developed, which was attributed to catheter migration. On week 25, the abdomen was decompressed through a peritoneal-amniotic shunt. Ascitis decreased thereafter, but oligohydramnios remained unchanged. The patient died 20 hours after a cesarean section was performed at the 31st week. The necropsy diagnoses were: posterior urethral valves, bilateral renal dysplasia and pulmonary hypoplasia. This case illustrates the difficulty in establishing a prognosis based on the prenatal data available at present. PMID:8217512
Specialization of reach function in human posterior parietal cortex.
Vesia, Michael; Crawford, J Douglas
2012-08-01
Posterior parietal cortex (PPC) plays an important role in the planning and control of goal-directed action. Single-unit studies in monkeys have identified reach-specific areas in the PPC, but the degree of effector and computational specificity for reach in the corresponding human regions is still under debate. Here, we review converging evidence spanning functional neuroimaging, parietal patient and transcranial magnetic stimulation studies in humans that suggests a functional topography for reach within human PPC. We contrast reach to saccade and grasp regions to distinguish functional specificity and also to understand how these different goal-directed actions might be coordinated at the cortical level. First, we present the current evidence for reach specificity in distinct modules in PPC, namely superior parietal occipital cortex, midposterior intraparietal cortex and angular gyrus, compared to saccade and grasp. Second, we review the evidence for hemispheric lateralization (both for hand and visual hemifield) in these reach representations. Third, we review evidence for computational reach specificity in these regions and finally propose a functional framework for these human PPC reach modules that includes (1) a distinction between the encoding of reach goals in posterior-medial PPC as opposed to reach movement vectors in more anterior-lateral PPC regions, and (2) their integration within a broader cortical framework for reach, grasp and eye-hand coordination. These findings represent both a confirmation and extension of findings that were previously reported for the monkey. PMID:22777102
Posterior foss avenous angiomas with drainage through the brain stem
Damiano, T.R.; Truwit, C.L. (Fitzsimons Army Medical Center, Aurora, CO (United States)); Dowd, C.F. (Univ. of California, San Francisco, CA (United States)); Symonds, D.L. (Denver General Hospital, CO (United States))
1994-04-01
To describe 11 cases of posterior fossa venous angiomas with drainage through the brain stem. Eleven cases of posterior fossa venous angioma with drainage through the brain stem were evaluated using MR. Correlation with known routes of venous drainage for the cerebellum and brain stem is made. Six of the 11 venous angiomas were found in the cerebellum, four in the brain stem; one involved both the cerebellum and brain stem. The cerebellar venous angiomas drained to subependymal veins about the fourth ventricle and dorsal pons. These then connected with an enlarged transmesencephalic or transpontine vein, to drain anteriorly to the anterior pontine veins. The brain stem angiomas had variable drainage depending on location. Evidence of hemorrhage was seen in five cases. Cerebellar and brain stem venous angiomas have several potential routes of drainage, including an enlarged vein traversing the pons, midbrain, or medulla. A knowledge of the normal venous anatomy of this region helps to understand the occurrence of these uncommon routes of venous drainage. 15 refs., 8 figs., 1 tab.
Finite Element Modeling of the Posterior Eye in Microgravity
NASA Technical Reports Server (NTRS)
Feola, Andrew; Raykin, Julia; Mulugeta, Lealem; Gleason, Rudolph; Myers, Jerry G.; Nelson, Emily S.; Samuels, Brian; Ethier, C. Ross
2015-01-01
Microgravity experienced during spaceflight affects astronauts in various ways, including weakened muscles and loss of bone density. Recently, visual impairment and intracranial pressure (VIIP) syndrome has become a major concern for space missions lasting longer than 30 days. Astronauts suffering from VIIP syndrome have changes in ocular anatomical and visual impairment that persist after returning to earth. It is hypothesized that a cephalad fluid shift in microgravity may increase the intracranial pressure (ICP), which leads to an altered biomechanical environment of the posterior globe and optic nerve sheath (ONS).Currently, there is a lack of knowledge of how elevated ICP may lead to vision impairment and connective tissue changes in VIIP. Our goal was to develop a finite element model to simulate the acute effects of elevated ICP on the posterior eye and optic nerve sheath. We used a finite element (FE) analysis approach to understand the response of the lamina cribrosa and optic nerve to the elevations in ICP thought to occur in microgravity and to identify which tissue components have the greatest impact on strain experienced by optic nerve head tissues.
Management of disorders of the posterior pelvic floor.
Berman, Loren; Aversa, John; Abir, Farshad; Longo, Walter E.
2005-01-01
INTRODUCTION: Constipation is a relatively common problem affecting 15 percent of adults in the Western world, and over half of these cases are related to pelvic floor disorders. This article reviews the clinical presentation and diagnostic approach to posterior pelvic floor disorders, including how to image and treat them. METHODS: A Pubmed search using keywords "rectal prolapse," "rectocele," "perineal hernia," and "anismus" was performed, and bibliographies of the revealed articles were cross-referenced to obtain a representative cross-section of the literature, both investigational studies and reviews, that are currently available on posterior pelvic floor disorders. DISCUSSION: Pelvic floor disorders can occur with or without concomitant physical anatomical defects, and there are a number of imaging modalities available to detect such abnormalities in order to decide on the appropriate course of treatment. Depending on the nature of the disorder, operative or non-operative therapy may be indicated. CONCLUSION: Correctly diagnosing pelvic floor disorders can be complex and challenging, and the various imaging modalities as well as clinical history and exam must be considered together in order to arrive at a diagnosis. PMID:16720016
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
On quantum vs. classical probability
Jochen Rau
2009-04-28
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.
Impact probability calculations --- comparison of methods
NASA Astrophysics Data System (ADS)
Rickman, H.; Wi?niowski, T.; Wajer, P.; Gabryszewski, R.; Valsecchi, G.
2014-07-01
We compare three different methods of statistical impact-probability calculations: our Hill sphere method that uses a super-sizing of the planet's collisional cross-section, the numerical averaging of Wetherill's (1967) formula, and the novel MOID method developed by us. The first and third are Monte Carlo simulations methods. In the first we count the number of Hill sphere passages for a large, random sample of orbits. In the third we search for orbits with MOID less than the collisional radius in a similar sample, calculating the MOID by the method of Wi?niowski and Rickman (2013), after which we compute the encounter timing range leading to collision for each selected object and compare with the target's orbital period. Our extensive comparisons use a constant semi-major axis of 3.5 au for the projectiles, and we focus on the parametric plane of perihelion distance and inclination. They show an excellent agreement among all the methods under practically all circumstances. However, in the vicinity of the singularities appearing in the Wetherill formulae (zero relative inclination, and equal perihelion distances) we find that only the MOID method yields accurate results. Due to the approximations inherent in the other methods, the super-sizing method underestimates the impact probability, and the Wetherill averaging overestimates it. This work was supported by the Polish National Science Center under Grant No. 2011/01/B/ST9/05442.
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
Pretty Purple Probabilities and Data Analysis!
NSDL National Science Digital Library
Ms. Nieman
2007-11-22
Plump Probability Problems need Played! The probability of the cards while playing the Probability Game! Find the probability of landing on each color, changing the parts size, when you spin the Probability Spinner! If you want a definition of any probability term.. click the word Definition ...
(Con)text-specific effects of visual dysfunction on reading in posterior cortical atrophy
Yong, Keir X.X.; Shakespeare, Timothy J.; Cash, Dave; Henley, Susie M.D.; Warren, Jason D.; Crutch, Sebastian J.
2014-01-01
Reading deficits are a common early feature of the degenerative syndrome posterior cortical atrophy (PCA) but are poorly understood even at the single word level. The current study evaluated the reading accuracy and speed of 26 PCA patients, 17 typical Alzheimer's disease (tAD) patients and 14 healthy controls on a corpus of 192 single words in which the following perceptual properties were manipulated systematically: inter-letter spacing, font size, length, font type, case and confusability. PCA reading was significantly less accurate and slower than tAD patients and controls, with performance significantly adversely affected by increased letter spacing, size, length and font (cursive < non-cursive), and characterised by visual errors (69% of all error responses). By contrast, tAD and control accuracy rates were at or near ceiling, letter spacing was the only perceptual factor to influence reading speed in the same direction as controls, and, in contrast to PCA patients, control reading was faster for larger font sizes. The inverse size effect in PCA (less accurate reading of large than small font size print) was associated with lower grey matter volume in the right superior parietal lobule. Reading accuracy was associated with impairments of early visual (especially crowding), visuoperceptual and visuospatial processes. However, these deficits were not causally related to a universal impairment of reading as some patients showed preserved reading for small, unspaced words despite grave visual deficits. Rather, the impact of specific types of visual dysfunction on reading was found to be (con)text specific, being particularly evident for large, spaced, lengthy words. These findings improve the characterisation of dyslexia in PCA, shed light on the causative and associative factors, and provide clear direction for the development of reading aids and strategies to maximise and sustain reading ability in the early stages of disease. PMID:24841985
(Con)text-specific effects of visual dysfunction on reading in posterior cortical atrophy.
Yong, Keir X X; Shakespeare, Timothy J; Cash, Dave; Henley, Susie M D; Warren, Jason D; Crutch, Sebastian J
2014-08-01
Reading deficits are a common early feature of the degenerative syndrome posterior cortical atrophy (PCA) but are poorly understood even at the single word level. The current study evaluated the reading accuracy and speed of 26 PCA patients, 17 typical Alzheimer's disease (tAD) patients and 14 healthy controls on a corpus of 192 single words in which the following perceptual properties were manipulated systematically: inter-letter spacing, font size, length, font type, case and confusability. PCA reading was significantly less accurate and slower than tAD patients and controls, with performance significantly adversely affected by increased letter spacing, size, length and font (cursive < non-cursive), and characterised by visual errors (69% of all error responses). By contrast, tAD and control accuracy rates were at or near ceiling, letter spacing was the only perceptual factor to influence reading speed in the same direction as controls, and, in contrast to PCA patients, control reading was faster for larger font sizes. The inverse size effect in PCA (less accurate reading of large than small font size print) was associated with lower grey matter volume in the right superior parietal lobule. Reading accuracy was associated with impairments of early visual (especially crowding), visuoperceptual and visuospatial processes. However, these deficits were not causally related to a universal impairment of reading as some patients showed preserved reading for small, unspaced words despite grave visual deficits. Rather, the impact of specific types of visual dysfunction on reading was found to be (con)text specific, being particularly evident for large, spaced, lengthy words. These findings improve the characterisation of dyslexia in PCA, shed light on the causative and associative factors, and provide clear direction for the development of reading aids and strategies to maximise and sustain reading ability in the early stages of disease. PMID:24841985
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 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.
EXPECTATIONS: POINTESTIMATES, PROBABILITY DISTRIBUTIONS, CONFIDENCE,
Chen, Yiling
within the range. Stated confidence cannot provide a measure and the confidence range provides only EXPECTATIONS: POINTESTIMATES, PROBABILITY DISTRIBUTIONS, CONFIDENCE, AND FORECASTS* David their confidence, using my method, which induces the respondents to reveal confidence, there is a sizable
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.
Outage probability at finite SNR
Akçaba, Cemal
2004-01-01
In this thesis, we present a technique to reduce the outage probability of a single user multiple input multiple output (MIMO) channel when a sub-optimal transceiver architecture is used. We show that in slow-fading ...
Logic, probability, and human reasoning.
Johnson-Laird, P N; Khemlani, Sangeet S; Goodwin, Geoffrey P
2015-04-01
This review addresses the long-standing puzzle of how logic and probability fit together in human reasoning. Many cognitive scientists argue that conventional logic cannot underlie deductions, because it never requires valid conclusions to be withdrawn - not even if they are false; it treats conditional assertions implausibly; and it yields many vapid, although valid, conclusions. A new paradigm of probability logic allows conclusions to be withdrawn and treats conditionals more plausibly, although it does not address the problem of vapidity. The theory of mental models solves all of these problems. It explains how people reason about probabilities and postulates that the machinery for reasoning is itself probabilistic. Recent investigations accordingly suggest a way to integrate probability and deduction. PMID:25770779
Essential Probability1 Michael Woodroofe
Woodroofe, Michael B.
Functions and Densities 69 5.1 Distribution Functions . . . . . . . . . . . . . . . . . . . . . . . . . . 69 5.2 Densities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72 5.3 Induced of probability may be motivated by games of chance such a card games and dice games. The resulting models
SUBJECTIVE PROBABILITY THE REAL THING
Fienberg, Stephen E.
.3 Laws of Expectation, 67 4.4 Mean and Median, 71 #12;2 4.5 Variance, 73 4.6 A Law of Large Numbers, 75 4 probabilities are "in the mind"--the subject's, say, yours. If you say the probability of rain is 70% you of this "dogmatism", the probabilistic mode of judgment offers a richer palate for depicting your state of mind
Chen, Zhi; Niu, Yin; Tang, Jun; Li, Lin; Feng, Zhou; Feng, Hua; Zhu, Gang
2015-08-01
Posterior communicating artery (PcomA) aneurysms in the presence of the fetal variant of posterior cerebral artery (PCA) often pose technical challenges for endovascular treatment because of a greater potential for ischemic injury with the fetal PCA compromise. The purpose of this study was to assess the feasibility and results of endovascular treatment for these lesions. We retrospectively reviewed our experience and results of endovascular treatments for a series of nine consecutive patients with PcomA aneurysms occurring at the origin of fetal PCAs at the Department of Neurosurgery of Southwest Hospital, Chongqing, China, between June 2011 and June 2014. Depending on the angiographic findings, location and shape of the aneurysms, various therapeutic strategies were used including coiling by single or double microcatheter, balloon remodeling technique, and single or Y-stenting technique. Overall, fetal PCA was preserved patent in all cases, and complete or near complete occlusion was achieved in 8/9 cases. There was no procedure-related morbidity or mortality. With the exception of one patient who died of pneumonia 6 weeks after treatment, no clinical evidence of neurologic deterioration and hemorrhagic complication was seen during the follow-up period in the remaining 8 patients. Our experience suggests that endovascular treatment is relatively safe and technically feasible in most patients with PcomA aneurysms in the presence of fetal PCA using multiple strategies. PMID:26111986
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
Transition Probabilities of Gd I
NASA Astrophysics Data System (ADS)
Bilty, Katherine; Lawler, J. E.; Den Hartog, E. A.
2011-01-01
Rare earth transition probabilities are needed within the astrophysics community to determine rare earth abundances in stellar photospheres. The current work is part an on-going study of rare earth element neutrals. Transition probabilities are determined by combining radiative lifetimes measured using time-resolved laser-induced fluorescence on a slow atom beam with branching fractions measured from high resolution Fourier transform spectra. Neutral rare earth transition probabilities will be helpful in improving abundances in cool stars in which a significant fraction of rare earths are neutral. Transition probabilities are also needed for research and development in the lighting industry. Rare earths have rich spectra containing 100's to 1000's of transitions throughout the visible and near UV. This makes rare earths valuable additives in Metal Halide - High Intensity Discharge (MH-HID) lamps, giving them a pleasing white light with good color rendering. This poster presents the work done on neutral gadolinium. We will report radiative lifetimes for 135 levels and transition probabilities for upwards of 1500 lines of Gd I. The lifetimes are reported to ±5% and the transition probabilities range from 5% for strong lines to 25% for weak lines. This work is supported by the National Science Foundation under grant CTS 0613277 and the National Science Foundation's REU program through NSF Award AST-1004881.
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.
Accurate Direct Illumination Using Iterative Adaptive Sampling
Bala, Kavita
become increasingly reliable and used for adaptive sampling. Creating the image block-by-block gives ourAccurate Direct Illumination Using Iterative Adaptive Sampling Michael Donikian, Bruce Walter use novel extensions for efficient antialiasing. Our adaptive multipass approach computes accurate
STOCHASTIC GENERATION OF BIOLOGICALLY ACCURATE BRAIN NETWORKS
a portion of the mouse brain. Very much in the same manner as genes generate proteins by providing templatesSTOCHASTIC GENERATION OF BIOLOGICALLY ACCURATE BRAIN NETWORKS A Thesis by ARAVIND ALURI Submitted OF BIOLOGICALLY ACCURATE BRAIN NETWORKS A Thesis by ARAVIND ALURI Submitted to the Office of Graduate Studies
An Accurate Method for Measuring Activation Energy
Xiang-Bai Chen; Jesse Huso; John L. Morrison; Leah Bergman
2005-01-01
In this letter, we present an accurate method for the measurement of activation energy. This method combined the excitation power dependent photoluminescence and temperature dependent photoluminescence together to obtain activation energy. We found with increasing temperature, there is a step transition from one emission mechanism to another. This step transition gives us an accurate measurement of activation energy. Using this
PHOTOGRAPHIC DEVICE FOR ACCURATELY MEASURING FISH
PHOTOGRAPHIC DEVICE FOR ACCURATELY MEASURING FISH / iwarine Biological Laboratory] APR 1 f) 1958, Commissioner PHOTOGRAPHIC DEVICE FOR ACCURATELY MEASURING FISH By Clifford W . Long Fishery Research Biologist. 228, Washington, D. C . November 1957 #12;ABSTRACT A photographic measuring device using two cameras
Accurate and Efficient Algorithms for Floating
Koev, Plamen
i i Accurate and Efficient Algorithms for Floating Point Computation J. Demmel and P. Koev 1 Abstract Our goal is to find accurate and efficient algorithms, when they exist, for evaluating rational how tiny the output is), and efficiency means that the algorithm runs in polynomial time. Our goal
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
Shi, Zhihong; Cai, Li; Liu, Shuai; Liu, Shuling; Han, Tong; Wang, Ying; Zhou, Yuying; Wang, Xinping; Gao, Shuo; Ji, Yong
2015-01-01
Posterior cortical atrophy (PCA) is a clinicoradiologic neurodegenerative syndrome characterized by predominant impairment of higher visual functions. Neuroimaging and neuropathological studies show that PCA is probably an atypical presentation of Alzheimer’s disease. However, in China PCA has rarely been studied and remains largely unknown. Our study therefore aimed to analyze the clinical manifestations and patterns of cerebral atrophy, amyloid beta deposition and regional glucose metabolism in Chinese PCA patients, comparing them directly with those of typical Alzheimer’s disease (TAD). Seven PCA patients, 6 TAD patients and 5 controls underwent neuropsychological assessment, MRI scan, 11C-PIB PET scan and 18F-FDG PET scan. Cerebral atrophy including ventricular enlargement, posterior atrophy and medial temporal lobe atrophy were evaluated with MRI. The uptake of 11C-PIB was quantified at the voxel level using the standardized uptake value ratio. Comparisons of regional cerebral glucose metabolism were calculated with statistical parametric mapping. PCA patients showed significant impairment on visuospatial function in neuropsychological assessment. And PCA patients showed more severe posterior atrophy and less severe left medial temporal lobe atrophy compared with TAD patients. The data from 11C-PIB PET scanning showed that amyloid beta deposition in PCA was comparable to TAD. Moreover, in PCA the results from 18F-FDG PET scanning revealed significant hypometabolism in the temporoparietooccipital region and identified specific hypometabolism in the right occipital lobe, compared with TAD. Our study thus provides a preliminary view of PCA in Chinese patients. A further study with a larger number of subjects would be recommended to confirm these findings. PMID:26267071
Transient contribution of left posterior parietal cortex to cognitive restructuring.
Sutoh, Chihiro; Matsuzawa, Daisuke; Hirano, Yoshiyuki; Yamada, Makiko; Nagaoka, Sawako; Chakraborty, Sudesna; Ishii, Daisuke; Matsuda, Shingo; Tomizawa, Haruna; Ito, Hiroshi; Tsuji, Hiroshi; Obata, Takayuki; Shimizu, Eiji
2015-01-01
Cognitive restructuring is a fundamental method within cognitive behavioural therapy of changing dysfunctional beliefs into flexible beliefs and learning to react appropriately to the reality of an anxiety-causing situation. To clarify the neural mechanisms of cognitive restructuring, we designed a unique task that replicated psychotherapy during a brain scan. The brain activities of healthy male participants were analysed using functional magnetic resonance imaging. During the brain scan, participants underwent Socratic questioning aimed at cognitive restructuring regarding the necessity of handwashing after using the restroom. The behavioural result indicated that the Socratic questioning effectively decreased the participants' degree of belief (DOB) that they must wash their hands. Alterations in the DOB showed a positive correlation with activity in the left posterior parietal cortex (PPC) while the subject thought about and rated own belief. The involvement of the left PPC not only in planning and decision-making but also in conceptualization may play a pivotal role in cognitive restructuring. PMID:25775998
Excellent fixation achieved with cementless posteriorly stabilized total knee arthroplasty.
Harwin, Steven F; Kester, Mark A; Malkani, Arthur L; Manley, Michael T
2013-01-01
Cementless posteriorly stabilized (PS) total knee arthroplasty has not been widely accepted primarily because of prior unpredictable results and concern about micromotion at the tibial fixation interface caused by the cam/post interaction. A prospective consecutive series of 114 cementless, tricompartmental periapatite-coated single-radius PS implants in 110 patients with a mean age 62 years was performed to determine if initial stability and biologic fixation could be achieved. At a mean follow-up of 36 months, all implants demonstrated radiographic evidence of stable biologic fixation with no evidence of loosening, osteolysis, stress shielding, or progressive radiolucent lines. Based on these early results, cementless, periapatite-coated single-radius PS total knee arthroplasty offers marked promise. PMID:22854342
Posterior reversible encephalopathy syndrome resulting from repeat bortezomib usage.
Nixon, N A; Parhar, K
2014-01-01
Bortezomib is a chemotherapeutic agent that acts via proteasome inhibition resulting in cellular apoptosis and inhibition of angiogenesis. Although widely accepted as treatment of multiple myeloma and non-Hodgkin's lymphoma, it has also been shown to be efficacious in a variety of solid tumours such as pancreatic and colonic. Posterior reversible encephalopathy syndrome (PRES) is a neuroradiological syndrome characterised by vasogenic oedema involving the postero-occipital cortical and subcortical white matter resulting in visual disturbances, seizures and altered mental status. Although in most cases PRES is reversible with removal of the provoking condition or drug, if not appropriately recognised and treated it may lead to permanent and life-threatening sequelae such as intracerebral haemorrhage and ischaemic infarction. We report a case of PRES associated with bortezomib therapy and contrast it with four other previously reported cases. Recognition of this potentially severe neurological complication is important with the increasingly widespread use of bortezomib. PMID:24903728
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
Iluvien: a new sustained delivery technology for posterior eye disease.
Kane, Frances E; Burdan, Judith; Cutino, Antonio; Green, Kenneth E
2008-09-01
Iluvien (fluocinolone acetonide intravitreal insert, Alimera Sciences, Inc.), a novel injectable intravitreal insert, is being studied to deliver a very low dose of a corticosteroid to the retina for up to 3 years as a treatment for diabetic macular edema. Using a proprietary 25-gauge injector system, an ophthalmologist injects the Iluvien insert, which uses the Medidur (Alimera Sciences, Inc.) technology, into the vitreous through a minimally invasive procedure in an out-patient setting. The placement of the device in the inferior vitreous has the potential to maximize drug at the retina while reducing exposure of the anterior chamber. Phase III studies are underway to test the safety and efficacy of Iluvien. This article offers a specific review of the Iluvien technology rather than an overview of the various intravitreal methods of treating posterior eye disease. PMID:18754752
A posterior approach for the excision of sacral chordoma.
Gennari, L; Azzarelli, A; Quagliuolo, V
1987-08-01
We report eight cases of sacrococcygeal chordoma treated by high sacral resection through S2 by a posterior approach, with the intention of achieving radical removal. The technique we describe is easier than the combined abdominosacral approach, and there have been no serious intra-operative or postoperative complications. The major technical problems were the margins of excision in the sacrum itself (one recurred) and in the perirectal soft tissues (four recurred), and the preservation of sacral nerve roots. When both S2 roots were preserved, sphincter problems were mild and reversible. One patient died from recurrence 32 months after operation and one was lost to follow-up at eight months. Six patients are alive with a median survival of three years; three of them are free of disease after 22, 36 and 80 months respectively. These results indicate the possibility of surgical cure of this malignant tumour. PMID:3611160
Changes in artistic style after minor posterior stroke
Annoni, J; Devuyst, G; Carota, A; Bruggimann, L; Bogousslavsky, J
2005-01-01
Background: Two professional painters experienced significant changes in their art as the main consequence of minor stroke located in the left occipital lobe or thalamus. Methods: The features of this artistic conversion were analysed on the basis of extensive neurological, neuropsychological, and psychiatric evaluations. Results: Both painters, initially unaware of the artistic changes, exhibited mild signs of executive dysfunction, but no general cognitive decline. The first painter, who showed mild visual-perceptive difficulties (dyschromatopsia and scotoma in his right upper visual field after left occipital stroke), together with increased anxiety and difficulty in emotional control, switched to a more stylised and symbolic art. The second painter, who also presented features of emotionalism related to his left latero-thalamic stroke, switched from an impressionist style to a more joyous and geometric, but more simplistic, abstract art. Conclusions: These findings show that mild cognitive and affective modifications due to focal posterior brain lesions can have significant repercussions on artistic expression. PMID:15897501
[Drug delivery to target the posterior segment of the eye].
Behar-Cohen, Francine
2004-01-01
Retinal diseases are nowadays the most common causes of vision threatening in developed countries. Therapeutic advances in this field are hindered by the difficulty to deliver drugs to the posterior segment of the eye. Due to anatomical barriers, the ocular biodisponibility of systemically administered drugs remains poor, and topical instillation is not adequate to achieve therapeutic concentrations of drugs in the back of the eye. Ocular drug delivery has thus become one of the main challenges of modern ophthalmology. A multidisciplinary research is being conducted worldwide including pharmacology, biomaterials, ophthalmology, pharmaceutics, and biology. New promising fields have been developed such as implantable or injectable slow release intravitreal devices and degradable polymers, dispersed polymeric systems for intraocular drug delivery, and transscleral delivery devices such as iontophoresis, osmotic pumps or intra-scleraly implantable materials. The first clinical applications emerging from this research are now taking place, opening new avenues for the treatment of retinal diseases. PMID:15329823
Transient contribution of left posterior parietal cortex to cognitive restructuring
Sutoh, Chihiro; Matsuzawa, Daisuke; Hirano, Yoshiyuki; Yamada, Makiko; Nagaoka, Sawako; Chakraborty, Sudesna; Ishii, Daisuke; Matsuda, Shingo; Tomizawa, Haruna; Ito, Hiroshi; Tsuji, Hiroshi; Obata, Takayuki; Shimizu, Eiji
2015-01-01
Cognitive restructuring is a fundamental method within cognitive behavioural therapy of changing dysfunctional beliefs into flexible beliefs and learning to react appropriately to the reality of an anxiety-causing situation. To clarify the neural mechanisms of cognitive restructuring, we designed a unique task that replicated psychotherapy during a brain scan. The brain activities of healthy male participants were analysed using functional magnetic resonance imaging. During the brain scan, participants underwent Socratic questioning aimed at cognitive restructuring regarding the necessity of handwashing after using the restroom. The behavioural result indicated that the Socratic questioning effectively decreased the participants' degree of belief (DOB) that they must wash their hands. Alterations in the DOB showed a positive correlation with activity in the left posterior parietal cortex (PPC) while the subject thought about and rated own belief. The involvement of the left PPC not only in planning and decision-making but also in conceptualization may play a pivotal role in cognitive restructuring. PMID:25775998
Posterior approach (Kraske procedure) for surgical treatment of presacral tumors
Aranda-Narváez, José Manuel; González-Sánchez, Antonio Jesús; Montiel-Casado, Custodia; Sánchez-Pérez, Belinda; Jiménez-Mazure, Carolina; Valle-Carbajo, Marta; Santoyo-Santoyo, Julio
2012-01-01
Presacral tumors are rare, but can comprise a great variety of histological types. Congenital tumors are the most common. Once the diagnosis is established, surgical resection is essential because of the potential for malignancy or infection. Previous biopsy is not necessary or may be even harmful. To decide the best surgical approach (abdominal, sacral or combined) an individual and multidisciplinary analysis must be carried out. We report three cases of cystic presacral masses in which a posterior approach (Kraske procedure) enabled complete resection, the only way to decrease local recurrence. All patients had a satisfactory recovery. A brief overview of retrorectal tumors is presented, focusing on classification, clinical presentation, diagnosis and surgical management. PMID:22655127