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1

Learning multilayer perceptrons efficiently  

CERN Multimedia

A learning algorithm for multilayer perceptrons is presented which is based on finding the principal components of a correlation matrix computed from the example inputs and their target outputs. For large networks our procedure needs far fewer examples to achieve good generalization than traditional on-line algorithms.

Bunzmann, C; Urbanczik, R

2001-01-01

2

Quaternionic Multilayer Perceptron with Local Analyticity  

Directory of Open Access Journals (Sweden)

Full Text Available A multi-layered perceptron type neural network is presented and analyzed in this paper. All neuronal parameters such as input, output, action potential and connection weight are encoded by quaternions, which are a class of hypercomplex number system. Local analytic condition is imposed on the activation function in updating neurons’ states in order to construct learning algorithm for this network. An error back-propagation algorithm is introduced for modifying the connection weights of the network.

Teijiro Isokawa; Haruhiko Nishimura; Nobuyuki Matsui

2012-01-01

3

Fourier-Lapped Multilayer Perceptron Method for Speech Quality Assessment  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The paper introduces a new objective method for speech quality assessment called Fourier-lapped multilayer perceptron (FLMLP). This method uses an overcomplete transform based on the discrete Fourier transform (DFT) and modulated lapped transform (MLT). This transform generates the DFT and the MLT s...

Moisés Vidal Ribeiro; Jayme Garcia Arnal Barbedo; João Marcos Travassos Romano; Amauri Lopes

4

Fourier-Lapped Multilayer Perceptron Method for Speech Quality Assessment  

Directory of Open Access Journals (Sweden)

Full Text Available The paper introduces a new objective method for speech quality assessment called Fourier-lapped multilayer perceptron (FLMLP). This method uses an overcomplete transform based on the discrete Fourier transform (DFT) and modulated lapped transform (MLT). This transform generates the DFT and the MLT speech spectral domains from which several relevant perceptual parameters are extracted. The proposed method also employs a multilayer perceptron neural network trained by a modified version of the scaled conjugated gradient method. This neural network maps the perceptual parameters into a subjective score. The numerical results show that FLMLP is an effective alternative to previous methods. As a result, it is worth stating that the techniques here described may be potentially useful to other researches facing the same kind of problem.

Ribeiro MoisésVidal; Barbedo Jayme Garcia Arnal; Romano JoãoMarcosTravassos; Lopes Amauri

2005-01-01

5

Efficient training of multilayer perceptrons using principal component analysis  

International Nuclear Information System (INIS)

A training algorithm for multilayer perceptrons is discussed and studied in detail, which relates to the technique of principal component analysis. The latter is performed with respect to a correlation matrix computed from the example inputs and their target outputs. Typical properties of the training procedure are investigated by means of a statistical physics analysis in models of learning regression and classification tasks. We demonstrate that the procedure requires by far fewer examples for good generalization than traditional online training. For networks with a large number of hidden units we derive the training prescription which achieves, within our model, the optimal generalization behavior

2005-01-01

6

A Choice of Input Variables for a Multilayer Perceptron  

International Nuclear Information System (INIS)

In the paper some aspects of multilayer perceptron (MLP) application to the problem of classifying the events presented by empirical samples of a finite volume are considered. The results of the MLP learning for various forms of the input data are analyzed and the reasons leading to the effect of an instantaneous learning of the MLP and rise of the neural network are investigated for the case when the input data are presented in a form of variational series. The problem of hidden layer neuron reduction without raising the recognition error is discussed. (author). 13 refs., 6 figs., 1 tab.

1994-01-01

7

Error correcting code using tree-like multilayer perceptron  

CERN Multimedia

An error correcting code using tree-like multilayer perceptron is proposed. An original message $\\mbi{s}^0$ is encoded into a codeword $\\mbi{y}_0$ using tree-like committee machine (committee tree) or tree-like parity machine (parity tree) whose transfer functions are non-monotonic. The codeword $\\mbi{y}_0$ is then transmitted via a Binary Asymmetric Channel (BAC) where it is corrupted by noise. The analytical performance of these schemes is investigated using the replica method of statistical mechanics. Under some specific conditions, all the schemes are shown to saturate the Shannon bound at the infinite codeword length limit.

Cousseau, Florent; Okada, Masato

2008-01-01

8

Combining Self Organizing Maps and Multilayer Perceptrons to Learn  

UK PubMed Central (United Kingdom)

Traditionally, the programming of bot behaviors for commercialcomputer games applies rule-based approaches. Buteven complex or fuzzyfied automatons cannot really challengeexperienced players. This contribution examineswhether bot programming can be treated as a pattern recognitionproblem and whether behaviors can be learned fromrecorded games. First, we sketch a technical computing interfaceto a commercial game that allows rapid prototyping ofclassifiers for bot programming. Then we discuss the use ofself organizing maps to represent manifolds of high dimensionalgame data and how multilayer perceptrons can modellocal characteristics of such manifolds. Finally, some experimentsin elementary behavior learning are presented.

C. Thurau; C. Bauckhage; G. Sagerer

9

A Parallel Framework for Multilayer Perceptron for Human Face Recognition  

Directory of Open Access Journals (Sweden)

Full Text Available Artificial neural networks have already shown their success in face recognition and similar complex pattern recognition tasks. However, a major disadvantage of the technique is that it is extremely slow during training for larger classes and hence not suitable for real-time complex problems such as pattern recognition. This is an attempt to develop a parallel framework for the training algorithm of a perceptron. In this paper, two general architectures for a Multilayer Perceptron (MLP) have been demonstrated. The first architecture is All-Class-in-One-Network (ACON) where all the classes are placed in a single network and the second one is One-Class-in-One-Network (OCON) where an individual single network is responsible for each and every class. Capabilities of these two architectures were compared and verified in solving human face recognition, which is a complex pattern recognition task where several factors affect the recognition performance like pose variations, facial expression changes, occlusions, and most importantly illumination changes. Experimental results show that the proposed OCON structure performs better than the conventional ACON in terms of network training convergence speed and which can be easily exercised in a parallel environment.

Debotosh Bhattacharjee; Dipak Kumar Basu; Mahantapas Kundu; Mita Nasipuri; Mrinal Kanti Bhowmik

2010-01-01

10

Theoretical Properties of Projection Based Multilayer Perceptrons with Functional Inputs  

CERN Multimedia

Many real world data are sampled functions. As shown by Functional Data Analysis (FDA) methods, spectra, time series, images, gesture recognition data, etc. can be processed more efficiently if their functional nature is taken into account during the data analysis process. This is done by extending standard data analysis methods so that they can apply to functional inputs. A general way to achieve this goal is to compute projections of the functional data onto a finite dimensional sub-space of the functional space. The coordinates of the data on a basis of this sub-space provide standard vector representations of the functions. The obtained vectors can be processed by any standard method. In our previous work, this general approach has been used to define projection based Multilayer Perceptrons (MLPs) with functional inputs. We study in this paper important theoretical properties of the proposed model. We show in particular that MLPs with functional inputs are universal approximators: they can approximate to ...

Rossi, F; Rossi, Fabrice; Conan-Guez, Brieuc

2006-01-01

11

Prediction of Parametric Roll Resonance by Multilayer Perceptron Neural Network  

DEFF Research Database (Denmark)

Parametric roll resonance is a ship stability related phenomenon that generates sudden large amplitude oscillations up to 30-40 degrees of roll. This can cause severe damage, and it can put the crew in serious danger. The need for a parametric rolling real time prediction system has been acknowledged in the last few years. This work proposes a prediction system based on a multilayer perceptron (MP) neural network. The training and testing of the MP network is accomplished by feeding it with simulated data of a three degrees-of-freedom nonlinear model of a fishing vessel. The neural network is shown to be capable of forecasting the ship’s roll motion in realistic scenarios.

Míguez González, M; López Peña, F.

2011-01-01

12

Classification of fused face images using multilayer perceptron neural network  

CERN Document Server

This paper presents a concept of image pixel fusion of visual and thermal faces, which can significantly improve the overall performance of a face recognition system. Several factors affect face recognition performance including pose variations, facial expression changes, occlusions, and most importantly illumination changes. So, image pixel fusion of thermal and visual images is a solution to overcome the drawbacks present in the individual thermal and visual face images. Fused images are projected into eigenspace and finally classified using a multi-layer perceptron. In the experiments we have used Object Tracking and Classification Beyond Visible Spectrum (OTCBVS) database benchmark thermal and visual face images. Experimental results show that the proposed approach significantly improves the verification and identification performance and the success rate is 95.07%. The main objective of employing fusion is to produce a fused image that provides the most detailed and reliable information. Fusion of multip...

Bhattacharjee, Debotosh; Nasipuri, Mita; Basu, Dipak Kumar; Kundu, Mahantapas

2010-01-01

13

Online learning dynamics of multilayer perceptrons with unidentifiable parameters  

International Nuclear Information System (INIS)

In the over-realizable learning scenario of multilayer perceptrons, in which the student network has a larger number of hidden units than the true or optimal network, some of the weight parameters are unidentifiable. In this case, the teacher network consists of a union of optimal subspaces included in the parameter space. The optimal subspaces, which lead to singularities, are known to affect the estimation performance of neural networks. Using statistical mechanics, we investigate the online learning dynamics of two-layer neural networks in the over-realizable scenario with unidentifiable parameters. We show that the convergence speed strongly depends on the initial parameter conditions. We also show that there is a quasi-plateau around the optimal subspace, which differs from the well-known plateaus caused by permutation symmetry. In addition, we discuss the property of the final learning state, relating this to the singular structures

2003-11-28

14

Prediction of zenith tropospheric delay by multi-layer perceptron  

Science.gov (United States)

The aim of the present study was to use the artificial neural network approach and specifically the multi-layer perceptron algorithm in order to predict total zenith tropospheric delay (ZTD) for various time spans of 1, 3 and 6 hours. The test data was ZTD values derived from the analysis centers of the EUREF Permanent tracking Network. The prediction process was applied to six EUREF permanent GPS stations for using period data of 2006 and 2007. The results obtained show an agreement at the order of few centimetres (2-3 cm) with those derived from EPN. Comparisons were also made with ZTD values calculated by other methods like the radiosonde observations and Saastamoinen model using ground measurements in order to confirm the final results and the feasibility of the neural network methodology.

Katsougiannopoulos, S.; Pikridas, C.

2009-12-01

15

An Analog Multilayer Perceptron Neural Network for a Portable Electronic Nose  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This study examines an analog circuit comprising a multilayer perceptron neural network (MLPNN). This study proposes a low-power and small-area analog MLP circuit to implement in an E-nose as a classifier, such that the E-nose would be relatively small, power-efficient, and portable. The analog MLP ...

Pan, Chih-Heng; Hsieh, Hung-Yi; Tang, Kea-Tiong

16

Characterisation of tequila according to their major volatile composition using multilayer perceptron neural networks.  

UK PubMed Central (United Kingdom)

Differentiation of silver, gold, aged and extra-aged tequila using 1-propanol, ethyl acetate, 2-methyl-1-propanol, 3-methyl-1-butanol and 2-methyl-1-butanol and furan derivatives like 5-(hydroxymethyl)-2-furaldehyde and 2-furaldehyde has been carried out. The content of 1-propanol, ethyl acetate, 2-methyl-1-propanol, 3-methyl-1-butanol and 2-methyl-1-butanol was determined by means of head space solid phase microextraction gas chromatography mass-spectrometry. 5-(Hydroxymethyl)-2-furaldehyde and 2-furaldehyde were determined by high performance liquid chromatography with diode array detection. Kruskal-Wallis test was used to highlight significant differences between types of tequila. Principal component analysis was applied as visualisation technique. Linear discriminant analysis and multilayer perceptron artificial neural networks were used to construct classification models. The best classification performance was obtained when multilayer perceptron model was applied.

Ceballos-Magaña SG; de Pablos F; Jurado JM; Martín MJ; Alcázar Á; Muñiz-Valencia R; Gonzalo-Lumbreras R; Izquierdo-Hornillos R

2013-02-01

17

Classification of glottic insufficiency and tension asymmetry using a multilayer perceptron.  

UK PubMed Central (United Kingdom)

OBJECTIVE: Laryngeal function can be evaluated from multiple perspectives, including aerodynamic input, acoustic output, and mucosal wave vibratory characteristics. To determine the classifying power of each of these, we used a multilayer perceptron artificial neural network (ANN) to classify data as normal, glottic insufficiency, or tension asymmetry. STUDY DESIGN: Case series analyzing data obtained from excised larynges simulating different conditions. METHODS: Aerodynamic, acoustic, and videokymographic data were collected from excised canine larynges simulating normal, glottic insufficiency, and tension asymmetry. Classification of samples was performed using a multilayer perceptron ANN. RESULTS: A classification accuracy of 84% was achieved when including all parameters. Classification accuracy dropped below 75% when using only aerodynamic or acoustic parameters and below 65% when using only videokymographic parameters. CONCLUSIONS: Samples were classified with the greatest accuracy when using a wide range of parameters. Decreased classification accuracies for individual groups of parameters demonstrate the importance of a comprehensive voice assessment when evaluating dysphonia.

Hoffman MR; Surender K; Devine EE; Jiang JJ

2012-12-01

18

k-nearest neighbors directed noise injection in multilayer perceptron training.  

UK PubMed Central (United Kingdom)

The relation between classifier complexity and learning set size is very important in discriminant analysis. One of the ways to overcome the complexity control problem is to add noise to the training objects, increasing in this way the size of the training set. Both the amount and the directions of noise injection are important factors which determine the effectiveness for classifier training. In this paper the effect is studied of the injection of Gaussian spherical noise and -nearest neighbors directed noise on the performance of multilayer perceptrons. As it is impossible to provide an analytical investigation for multilayer perceptrons, a theoretical analysis is made for statistical classifiers. The goal is to get a better understanding of the effect of noise injection on the accuracy of sample-based classifiers. By both empirical as well as theoretical studies, it is shown that the -nearest neighbors directed noise injection is preferable over the Gaussian spherical noise injection for data with low intrinsic dimensionality.

Skurichina M; Raudys S; Duin RW

2000-01-01

19

K-Nearest Neighbours Directed Noise Injection in Multilayer Perceptron Training  

UK PubMed Central (United Kingdom)

The relation between classifier complexity and learning set size is very important in discriminant analysis. One of theways to overcome the complexity control problem is to add noise to the training objects, increasing in this way thesize of the training set. Both, the amount and the directions of noise injection are important factors which determinethe effectiveness for classifier training. In this paper the effect is studied of the injection of Gaussian spherical noiseand k-nearest neighbours directed noise on the performance of multilayer perceptrons. As it is impossible to providean analytical investigation for multilayer perceptrons, a theoretical analysis is made for statistical classifiers. The goalis to get a better understanding of the effect of noise injection on the accuracy of sample based classifiers. By both,empirical as well as theoretical studies, it is shown that the k-nearest neighbours directed noise injection is preferableover the Gaussian spherical noise injection for data with low intrinsic dimensionality.

M. Skurichina

20

Optimal Parameter for the Training of Multilayer Perceptron Neural Networks by Using Hierarchical Genetic Algorithm  

International Nuclear Information System (INIS)

[en] This paper deals with the controversial topic of the selection of the parameters of a genetic algorithm, in this case hierarchical, used for training of multilayer perceptron neural networks for the binary classification. The parameters to select are the crossover and mutation probabilities of the control and parametric genes and the permanency percent. The results can be considered as a guide for using this kind of algorithm.

2008-11-06

 
 
 
 
21

Experts Fusion and Multilayer Perceptron Based on Belief Learning for Sonar Image Classification  

CERN Document Server

The sonar images provide a rapid view of the seabed in order to characterize it. However, in such as uncertain environment, real seabed is unknown and the only information we can obtain, is the interpretation of different human experts, sometimes in conflict. In this paper, we propose to manage this conflict in order to provide a robust reality for the learning step of classification algorithms. The classification is conducted by a multilayer perceptron, taking into account the uncertainty of the reality in the learning stage. The results of this seabed characterization are presented on real sonar images.

Martin, Arnaud

2008-01-01

22

ECG biometric using multilayer perceptron and radial basis function neural networks.  

UK PubMed Central (United Kingdom)

This paper proposes a new method to identify people using Electrocardiogram (ECG), particularly the QRS complex which has been proven to be stable against heart rate variability and convenient to be used alone as a biometric feature. 324 QRS complexes are extracted from ECGs of 18 subjects in Physionet's MIT-BIH Normal Sinus Rhythm Database (NSRDB). Multilayer Perceptron (MLP) and Radial Basis Function (RBF) neural networks are used to classify those QRS complexes. If the training data are chosen carefully to cover a wide range of input values (i.e. QRS complexes), then the classification accuracy rates can reach above 98% using MLP and 97% using RBF.

Mai V; Khalil I; Meli C

2011-01-01

23

Multilayered perceptron neural networks to compute energy losses in magnetic cores  

International Nuclear Information System (INIS)

This paper presents a new approach based on multilayered perceptrons (MLPs) to compute the specific energy losses of toroidal wound cores built from 3% SiFe 0.27 mm thick M4, 0.1 and 0.08 mm thin gauge electrical steel strips. The MLP has been trained by a back-propagation and extended delta-bar-delta learning algorithm. The results obtained by using the MLP model were compared with a commonly used conventional method. The comparison has shown that the proposed model improved loss estimation with respect to the conventional method.

2006-01-01

24

Multilayered perceptron neural networks to compute energy losses in magnetic cores  

Energy Technology Data Exchange (ETDEWEB)

This paper presents a new approach based on multilayered perceptrons (MLPs) to compute the specific energy losses of toroidal wound cores built from 3% SiFe 0.27 mm thick M4, 0.1 and 0.08 mm thin gauge electrical steel strips. The MLP has been trained by a back-propagation and extended delta-bar-delta learning algorithm. The results obtained by using the MLP model were compared with a commonly used conventional method. The comparison has shown that the proposed model improved loss estimation with respect to the conventional method.

Kucuk, Ilker [Physics Department, Faculty of Arts and Sciences, Uludag University, Gorukle Campus 16059, Bursa (Turkey)]. E-mail: ikucuk@uludag.edu.tr

2006-12-15

25

Missing value imputation on missing completely at random data using multilayer perceptrons.  

UK PubMed Central (United Kingdom)

Data mining is based on data files which usually contain errors in the form of missing values. This paper focuses on a methodological framework for the development of an automated data imputation model based on artificial neural networks. Fifteen real and simulated data sets are exposed to a perturbation experiment, based on the random generation of missing values. These data set sizes range from 47 to 1389 records. A perturbation experiment was performed for each data set where the probability of missing value was set to 0.05. Several architectures and learning algorithms for the multilayer perceptron are tested and compared with three classic imputation procedures: mean/mode imputation, regression and hot-deck. The obtained results, considering different performance measures, not only suggest this approach improves the quality of a database with missing values, but also the best results are clearly obtained using the Multilayer Perceptron model in data sets with categorical variables. Three learning rules (Levenberg-Marquardt, BFGS Quasi-Newton and Conjugate Gradient Fletcher-Reeves Update) and a small number of hidden nodes are recommended.

Silva-Ramírez EL; Pino-Mejías R; López-Coello M; Cubiles-de-la-Vega MD

2011-01-01

26

Image Binarization Using Multi-Layer Perceptron: A Semi-Supervised Approach  

Directory of Open Access Journals (Sweden)

Full Text Available In this paper, we have discussed the Image Binarization technique using Multilayer Perceptron (MLP). The purpose of Image Binarization is to extract the lightness (brightness, density) as a feature amount from the Image. It converts a gray-scale image of up to 256 gray levels to a black and white image. We use Backpropagation algorithm for training MLP. It is a supervised learning technique. Here Kmeans clustering algorithm has been used for clustering a 256 × 256 gray-level image. The dataset obtained by this is fed to the MLP and processed in a Semi-Supervised way where some training samples are taken as Known patterns (for training) and others as Unknown patterns. Finally through this approach a Binarized image is produced.

Amlan Raychaudhuri; Jayanta Dutta

2012-01-01

27

Statistical mechanics of an error correcting code using monotonic and nonmonotonic treelike multilayer perceptrons.  

UK PubMed Central (United Kingdom)

An error correcting code using a treelike multilayer perceptron is proposed. An original message s0 is encoded into a codeword y0 using a treelike committee machine (committee tree) or a treelike parity machine (parity tree). Based on these architectures, several schemes featuring monotonic or nonmonotonic units are introduced. The codeword y0 is then transmitted via a binary asymmetric channel where it is corrupted by noise. The analytical performance of these schemes is investigated using the replica method of statistical mechanics. Under some specific conditions, some of the proposed schemes are shown to saturate the Shannon bound at the infinite codeword length limit. The influence of the monotonicity of the units on the performance is also discussed.

Cousseau F; Mimura K; Okada M

2010-02-01

28

A New Approach to Predicting Bankruptcy: Combining DEA and Multi-Layer Perceptron  

Directory of Open Access Journals (Sweden)

Full Text Available The question of financial health and sustenance of a firm is so intriguing that it has spanned numerous studies. For investors,stakeholders and lenders, assessing the risk associated with an enterprise is vital. Several tools have been formulated to deal with predicting the solvency of a firm. This paper attempts to combine Data Envelopment Analysis and Multi-Layer Perceptron (MLP) to suggest a new method for prediction of bankruptcy that not only focusses on historical financial data of firms that filed for bankruptcy like other past studies but also takes into account the data of those firms that were likely to do so. This method thus identifies firms that have a high chance of facing bankruptcy along with those that have filed for bankruptcy. The performance of this procedure is compared with MLP. The suggested method outperforms MLP in prediction of bankruptcy.

Ayan Mukhopadhyay; Suman Tiwari; Ankit Narsaria; Bhaskar Roy Karmaker

2012-01-01

29

Recognition of Printed Bangla Document from Textual Image Using Multi-Layer Perceptron (MLP) Neural Network  

Directory of Open Access Journals (Sweden)

Full Text Available This paper focuses on the segmentation of printed Bangla characters for efficient recognition of the characters. The segmentation of characters is an important step in the process of character recognitions because it allows the system to classify the characters more accurately and quickly. The system takes the scanned image file of the printed document as its input. A structural feature extraction method is used to extract the feature. In this case, each individual Bangla character is converted to a M × N feature matrix. A Multi-Layer Perceptron (MLP) neural network with back propagation algorithm is chosen to feed the feature matrix to train with the set of input patterns and to develop knowledge to classify the character. The effectiveness of the system has been tested with several printed documents and the success rates in all cases are over 90%.

Md. Musfique Anwar; Nasrin Sultana Shume; P. K. M. Moniruzzaman; Md. Al-Amin Bhuiyan

2010-01-01

30

An Analog Multilayer Perceptron Neural Network for a Portable Electronic Nose  

Science.gov (United States)

This study examines an analog circuit comprising a multilayer perceptron neural network (MLPNN). This study proposes a low-power and small-area analog MLP circuit to implement in an E-nose as a classifier, such that the E-nose would be relatively small, power-efficient, and portable. The analog MLP circuit had only four input neurons, four hidden neurons, and one output neuron. The circuit was designed and fabricated using a 0.18 ?m standard CMOS process with a 1.8 V supply. The power consumption was 0.553 mW, and the area was approximately 1.36 × 1.36 mm2. The chip measurements showed that this MLPNN successfully identified the fruit odors of bananas, lemons, and lychees with 91.7% accuracy.

Pan, Chih-Heng; Hsieh, Hung-Yi; Tang, Kea-Tiong

2013-01-01

31

An Analog Multilayer Perceptron Neural Network for a Portable Electronic Nose  

Directory of Open Access Journals (Sweden)

Full Text Available This study examines an analog circuit comprising a multilayer perceptron neural network (MLPNN). This study proposes a low-power and small-area analog MLP circuit to implement in an E-nose as a classifier, such that the E-nose would be relatively small, power-efficient, and portable. The analog MLP circuit had only four input neurons, four hidden neurons, and one output neuron. The circuit was designed and fabricated using a 0.18 ?m standard CMOS process with a 1.8 V supply. The power consumption was 0.553 mW, and the area was approximately 1.36 × 1.36 mm2. The chip measurements showed that this MLPNN successfully identified the fruit odors of bananas, lemons, and lychees with 91.7% accuracy.

Chih-Heng Pan; Hung-Yi Hsieh; Kea-Tiong Tang

2012-01-01

32

Recognition of Epileptiform Patterns in the Human Electroencephalogram Using Multi-Layer Perceptron  

Directory of Open Access Journals (Sweden)

Full Text Available Automatic detection of epileptiform patterns is highly desirable during continuous monitoring of patients with epilepsy. This paper describes an unconvential system for automatic off-line recognition of epileptic sharp transients in the human electroencephalogram (EEG), based on a standard neural network architecture - multi-layer perceptron (MLP), and implemented on a Silicon Graphics Indigo workstation. The system makes comprehensive use of wide spatial contextual information available on 12 channels of EEG and takes advantage of discrete dyadic wavelet transform (DDWT) for efficient parameterisation of EEG data. The EEG database consists of 12 patients, 7 of which are used in the process of training of MLP. The resulting MLP is presented with the testing data set consisting of all data vectors from all 12 patients, and is shown to be capable to recognise a wide variety of epileptic signals.

J. Magdolen; F. Zidek; V. Mokran

1995-01-01

33

An analog multilayer perceptron neural network for a portable electronic nose.  

UK PubMed Central (United Kingdom)

This study examines an analog circuit comprising a multilayer perceptron neural network (MLPNN). This study proposes a low-power and small-area analog MLP circuit to implement in an E-nose as a classifier, such that the E-nose would be relatively small, power-efficient, and portable. The analog MLP circuit had only four input neurons, four hidden neurons, and one output neuron. The circuit was designed and fabricated using a 0.18 ?m standard CMOS process with a 1.8 V supply. The power consumption was 0.553 mW, and the area was approximately 1.36 × 1.36 mm2. The chip measurements showed that this MLPNN successfully identified the fruit odors of bananas, lemons, and lychees with 91.7% accuracy.

Pan CH; Hsieh HY; Tang KT

2013-01-01

34

Statistical mechanics of an error correcting code using monotonic and nonmonotonic treelike multilayer perceptrons.  

Science.gov (United States)

An error correcting code using a treelike multilayer perceptron is proposed. An original message s0 is encoded into a codeword y0 using a treelike committee machine (committee tree) or a treelike parity machine (parity tree). Based on these architectures, several schemes featuring monotonic or nonmonotonic units are introduced. The codeword y0 is then transmitted via a binary asymmetric channel where it is corrupted by noise. The analytical performance of these schemes is investigated using the replica method of statistical mechanics. Under some specific conditions, some of the proposed schemes are shown to saturate the Shannon bound at the infinite codeword length limit. The influence of the monotonicity of the units on the performance is also discussed. PMID:20365527

Cousseau, Florent; Mimura, Kazushi; Okada, Masato

2010-02-01

35

Exchange rate prediction with multilayer perceptron neural network using gold price as external factor  

Directory of Open Access Journals (Sweden)

Full Text Available In this paper, the problem of predicting the exchange rate time series in the foreign exchange rate market is going to be solved using a time-delayed multilayer perceptron neural network with gold price as external factor. The input for the learning phase of the artificial neural network are the exchange rate data of the last five days plus the gold price in two different currencies of the exchange rate as the external factor for helping the artificial neural network improving its forecast accuracy. The five-day delay has been chosen because of the weekly cyclic behavior of the exchange rate time series with the consideration of two holidays in a week. The result of forecasts are then compared with using the multilayer peceptron neural network without gold price external factor by two most important evaluation techniques in the literature of exchange rate prediction. For the experimental analysis phase, the data of three important exchange rates of EUR/USD, GBP/USD, and USD/JPY are used.

Mohammad Fathian; Arash N.Kia

2012-01-01

36

Wideband dynamic behavioral modeling of reflective semiconductor optical amplifiers using a tapped-delay multilayer perceptron.  

UK PubMed Central (United Kingdom)

In this paper, we propose a wideband dynamic behavioral model for a bulk reflective semiconductor optical amplifier (RSOA) used as a modulator in colorless radio over fiber (RoF) systems using a tapped-delay multilayer perceptron (TDMLP). 64 quadrature amplitude modulation (QAM) signals with 20 Msymbol/s were used to train, validate and test the model. Nonlinear distortion and dynamic effects induced by the RSOA modulator are demonstrated. The parameters of the model such as the number of nodes in the hidden layer and memory depth were optimized to ensure the generality and accuracy. The normalized mean square error (NMSE) is used as a figure of merit. The NMSE was up to -44.33 dB when the number of nodes in the hidden layer and memory depth were set to 20 and 3, respectively. The TDMLP model can accurately approximate to the dynamic characteristics of the RSOA modulator. The dynamic AM-AM and dynamic AM-PM distortions of the RSOA modulator are drawn. The results show that the single hidden layer TDMLP can provide accurate approximation for behaviors of the RSOA modulator.

Liu Z; Violas MA; Carvalho NB

2013-02-01

37

Wideband dynamic behavioral modeling of reflective semiconductor optical amplifiers using a tapped-delay multilayer perceptron.  

Science.gov (United States)

In this paper, we propose a wideband dynamic behavioral model for a bulk reflective semiconductor optical amplifier (RSOA) used as a modulator in colorless radio over fiber (RoF) systems using a tapped-delay multilayer perceptron (TDMLP). 64 quadrature amplitude modulation (QAM) signals with 20 Msymbol/s were used to train, validate and test the model. Nonlinear distortion and dynamic effects induced by the RSOA modulator are demonstrated. The parameters of the model such as the number of nodes in the hidden layer and memory depth were optimized to ensure the generality and accuracy. The normalized mean square error (NMSE) is used as a figure of merit. The NMSE was up to -44.33 dB when the number of nodes in the hidden layer and memory depth were set to 20 and 3, respectively. The TDMLP model can accurately approximate to the dynamic characteristics of the RSOA modulator. The dynamic AM-AM and dynamic AM-PM distortions of the RSOA modulator are drawn. The results show that the single hidden layer TDMLP can provide accurate approximation for behaviors of the RSOA modulator. PMID:23481795

Liu, Zhansheng; Violas, Manuel Alberto; Carvalho, Nuno Borges

2013-02-11

38

Geomagnetic Dst index forecast using a multilayer perceptrons artificial neural network  

International Nuclear Information System (INIS)

[en] Complete text of publication follows. The best known manifestations of the impact of solar wind on the magnetosphere are the geomagnetic storms. The prediction of geomagnetic field behavior allows the alert of geomagnetic storms occurrence, as those phenomena can cause many damages in the planet. The Artificial Intelligence tools have been applied in many multidisciplinary studies, covering several areas of knowledge, as a choice of approach to the solution of problems with characteristics like non-linearity, imprecision, and other features that can not be easily solved with conventional computational models. Techniques such as Artificial Neural Networks, Expert Systems and Decision Trees have been used in the Space Weather studies to perform tasks such as forecasting geomagnetic storms and the investigation of rules and parameters related on its occurrence. The main focus of this work is on forecasting the geomagnetic field behavior, represented this time by the Dst index, using for that task, mainly, the interplanetary magnetic field components and solar wind data. The tool chosen here to solve the non-linear problem was a Multi-layer Perceptrons Artificial Neural Network, trained with the backpropagation algorithm. Unlike what was done in other studies, we chose to predict calm and disturbed periods like, for example, a full month of data, for application in a real time forecasting system. It was possible to predict the geomagnetic Dst index one or two hours before with great percentage efficiency.

2009-01-01

39

Face Recognition through Multilayer Perceptron (MLP) and Learning Vector Quantization (LVQ)  

Directory of Open Access Journals (Sweden)

Full Text Available Face recognition is challenging problems and there is still a lot of work that needs to be done in this area. Over the past ten years, face recognition has received substantial attention from researchers in biometrics, pattern recognition, computer vision, and cognitive psychology communities. This common interest in facial recognition technology among researchers working in diverse fields is motivated both by the remarkable ability to recognize people and by the increased attention being devoted to security applications. Applications of face recognition can be found in security, tracking, multimedia, and entertainment domains.This paper presents a face recognition system using artificial neural network. Here, we have designed a neural network with some own set network parameters. The results presented here have been obtained using two basic methods: multilayer perceptron (MLP), and learning vector quantization (LVQ). In both cases, two kinds of data have been fed to the classifiers: reduced resolution images (gray level or segmented), and feature vectors. The experimental results also show that, for the approaches considered here, analyzing gray level images produced better results than analyzing geometrical features, either because of the errors introduced during their extraction or because the original images have a richer information content. Furthermore, training times were much shorter for LVQ than for MLP. On the other hand, MLP achieved lower error rates when dealing with geometrical features.

Dr. Ikvinderpal Singh

2012-01-01

40

Predicting odorant chemical class from odorant descriptor values with an assembly of multi-layer perceptrons.  

UK PubMed Central (United Kingdom)

Chemical descriptors are a way to define information concerning the physical, chemical and biological properties of a chemical compound. Machine learning methods such as the Artificial Neural Network (ANN) can be used to learn and predict such compounds by training on the compounds chemical descriptors. The motivation of our work is to predict odorant molecules for the development of an artificial biosensor. In this work, we demonstrate using a set of 32 optimized odorant descriptors how an assembly of MultiLayer Perceptrons (MLPs) can be successfully trained to differentiate among eight different chemical classes of odorant. In this communication, we demonstrate how it is possible to predict all 15/15 vectors from an unseen validation set with a high average prediction accuracy of 88.5% for the validation vectors. Furthermore, an introduction of a 10% noise injection level to the training set, increased the learning rate significantly as well as improve the average prediction accuracy of the MLPs to 92% for the validating vectors. Thus, this work indicates the promise of using odorant descriptor values to accurately predict chemical class and so move us forward to the realisation of an artificial odorant biosensor.

Bachtiar LR; Unsworth CP; Newcomb RD; Crampin EJ

2011-01-01

 
 
 
 
41

Analog Multilayer Perceptron Circuit with On-chip Learning: Portable Electronic Nose  

Science.gov (United States)

This article presents an analog multilayer perceptron (MLP) neural network circuit with on-chip back propagation learning. This low power and small area analog MLP circuit is proposed to implement as a classifier in an electronic nose (E-nose). Comparing with the E-nose using microprocessor or FPGA as a classifier, the E-nose applying analog circuit as a classifier can be faster and much smaller, demonstrate greater power efficiency and be capable of developing a portable E-nose [1]. The system contains four inputs, four hidden neurons, and only one output neuron; this simple structure allows the circuit to have a smaller area and less power consumption. The circuit is fabricated using TSMC 0.18 ?m 1P6M CMOS process with 1.8 V supply voltage. The area of this chip is 1.353×1.353 mm2 and the power consumption is 0.54 mW. Post-layout simulations show that the proposed analog MLP circuit can be successively trained to identify three kinds of fruit odors.

Pan, Chih-Heng; Tang, Kea-Tiong

2011-09-01

42

Anaerobic tapered fluidized bed reactor for starch wastewater treatment and modeling using multilayer perceptron neural network.  

UK PubMed Central (United Kingdom)

Anaerobic treatability of synthetic sago wastewater was investigated in a laboratory anaerobic tapered fluidized bed reactor (ATFBR) with a mesoporous granular activated carbon (GAC) as a support material. The experimental protocol was defined to examine the effect of the maximum organic loading rate (OLR), hydraulic retention time (HRT), the efficiency of the reactor and to report on its steady-state performance. The reactor was subjected to a steady-state operation over a range of OLR up to 85.44 kg COD/(m3 x d). The COD removal efficiency was found to be 92% in the reactor while the biogas produced in the digester reached 25.38 m3/(m3 x d) of the reactor. With the increase of OLR from 83.7 kg COD/(m3 x d), the COD removal efficiency decreased. Also an artificial neural network (ANN) model using multilayer perceptron (MLP) has been developed for a system of two input variable and five output dependent variables. For the training of the input-output data, the experimental values obtained have been used. The output parameters predicted have been found to be much closer to the corresponding experimental ones and the model was validated for 30% of the untrained data. The mean square error (MSE) was found to be only 0.0146.

Parthiban R; Iyer PV; Sekaran G

2007-01-01

43

Cross Validation Evaluation for Breast Cancer Prediction Using Multilayer Perceptron Neural Networks  

Directory of Open Access Journals (Sweden)

Full Text Available Problem statement: The presence of metastasis in the regional lymph nodes is the most important factor in predicting prognosis in breast cancer. Many biomarkers have been identified that appear to relate to the aggressive behaviour of cancer. However, the nonlinear relation of these markers to nodal status and also the existence of complex interaction between markers have prohibited an accurate prognosis. Approach: The aim of this study is to investigate the effectiveness of a Multilayer Perceptron (MLP) for predicting breast cancer progression using a set of four biomarkers of breast tumors. The biomarkers include DNA ploidy, cell cycle distribution (G0G1/G2M), steroid receptors (ER/PR) and S-Phase Fraction (SPF). A further objective of the study is to explore the predictive potential of these markers in defining the state of nodal involvement in breast cancer. Two methods of outcome evaluation viz. stratified and simple k-fold Cross Validation (CV) are studied in order to assess their accuracy and reliability for neural network validation. Criteria such as output accuracy, sensitivity and specificity are used for selecting the best validation technique besides evaluating the network outcome for different combinations of markers. Results: The results show that stratified 2-fold CV is more accurate and reliable compared to simple k-fold CV as it obtains a higher accuracy and specificity and also provides a more stable network validation in terms of sensitivity. Best prediction results are obtained by using an individual marker-SPF which obtains an accuracy of 65%. Conclusion/Recommendations: Our findings suggest that MLP-based analysis provides an accurate and reliable platform for breast cancer prediction given that an appropriate design and validation method is employed.

Shirin A. Mojarad; Satnam S. Dlay; Wai L. Woo; Gajanan V. Sherbet

2011-01-01

44

Fast accurate MEG source localization using a multilayer perceptron trained with real brain noise  

International Nuclear Information System (INIS)

Iterative gradient methods such as Levenberg-Marquardt (LM) are in widespread use for source localization from electroencephalographic (EEG) and magnetoencephalographic (MEG) signals. Unfortunately, LM depends sensitively on the initial guess, necessitating repeated runs. This, combined with LM's high per-step cost, makes its computational burden quite high. To reduce this burden, we trained a multilayer perceptron (MLP) as a real-time localizer. We used an analytical model of quasistatic electromagnetic propagation through a spherical head to map randomly chosen dipoles to sensor activities according to the sensor geometry of a 4D Neuroimaging Neuromag-122 MEG system, and trained a MLP to invert this mapping in the absence of noise or in the presence of various sorts of noise such as white Gaussian noise, correlated noise, or real brain noise. A MLP structure was chosen to trade off computation and accuracy. This MLP was trained four times, with each type of noise. We measured the effects of initial guesses on LM performance, which motivated a hybrid MLP-start-LM method, in which the trained MLP initializes LM. We also compared the localization performance of LM, MLPs, and hybrid MLP-start-LMs for realistic brain signals. Trained MLPs are much faster than other methods, while the hybrid MLP-start-LMs are faster and more accurate than fixed-4-start-LM. In particular, the hybrid MLP-start-LM initialized by a MLP trained with the real brain noise dataset is 60 times faster and is comparable in accuracy to random-20-start-LM, and this hybrid system (localization error: 0.28 cm, computation time: 36 ms) shows almost as good performance as optimal-1-start-LM (localization error: 0.23 cm, computation time: 22 ms), which initializes LM with the correct dipole location. MLPs trained with noise perform better than the MLP trained without noise, and the MLP trained with real brain noise is almost as good an initial guesser for LM as the correct dipole location. (author) )

2002-07-21

45

Exploiting Heavy Tails in Training Times of Multilayer Perceptrons. A Case Study with the UCI Thyroid Disease Database  

CERN Document Server

The random initialization of weights of a multilayer perceptron makes it possible to model its training process as a Las Vegas algorithm, i.e. a randomized algorithm which stops when some required training error is obtained, and whose execution time is a random variable. This modelling is used to perform a case study on a well-known pattern recognition benchmark: the UCI Thyroid Disease Database. Empirical evidence is presented of the training time probability distribution exhibiting a heavy tail behavior, meaning a big probability mass of long executions. This fact is exploited to reduce the training time cost by applying two simple restart strategies. The first assumes full knowledge of the distribution yielding a 40% cut down in expected time with respect to the training without restarts. The second, assumes null knowledge, yielding a reduction ranging from 9% to 23%.

Cebrian, Manuel

2007-01-01

46

Comparison between Multi-Layer Perceptron and Radial Basis Function Networks for Sediment Load Estimation in a Tropical Watershed  

Directory of Open Access Journals (Sweden)

Full Text Available Prediction of highly non-linear behavior of suspended sediment flow in rivers has prime importance in environmental studies and watershed management. In this study, the predictive performance of two Artificial Neural Networks (ANNs), namely Radial Basis Function (RBF) and Multi-Layer Perceptron (MLP) were compared. Time series data of daily suspended sediment discharge and water discharge at the Langat River, Malaysia were used for training and testing the networks. Mean Square Error (MSE), Normalized Mean Square Error (NMSE) and correlation coefficient (r) were used for performance evaluation of the models. Using the testing data set, both models produced a similar level of robustness in sediment load simulation. The MLP network model showed a slightly better output than the RBF network model in predicting suspended sediment discharge, especially in the training process. However, both ANNs showed a weak robustness in estimating large magnitudes of sediment load.

Hadi Memarian; Siva Kumar Balasundram

2012-01-01

47

U-shaped learning and frequency effects in a multi-layered perceptron: implications for child language acquisition.  

UK PubMed Central (United Kingdom)

A three-layer back-propagation network is used to implement a pattern association task in which four types of mapping are learned. These mappings, which are considered analogous to those which characterize the relationship between the stem and past tense forms of English verbs, include arbitrary mappings, identity mappings, vowel changes, and additions of a suffix. The degree of correspondence between parallel distributed processing (PDP) models which learn mappings of this sort (e.g., Rumelhart & McClelland, 1986, 1987) and children's acquisition of inflectional morphology has recently been at issue in discussions of the applicability of PDP models to the study of human cognition and language (Pinker & Mehler, 1989; Bever, in press). In this paper, we explore the capacity of a network to learn these types of mappings, focusing on three major issues. First, we compare the performance of a single-layered perceptron similar to the one used by Rumelhart and McClelland with a multi-layered perceptron. The results suggest that it is unlikely that a single-layered perceptron is capable of finding an adequate solution to the problem of mapping stems and past tense forms in input configurations that are sufficiently analogous to English. Second, we explore the input conditions which determine learning in these networks. Several factors that characterize linguistic input are investigated: (a) the nature of the mapping performed by the network (arbitrary, suffixation, identity, and vowel change); (b) the competition effects that arise when the task demands simultaneous learning of distinct mapping types; (c) the role of the type and token frequency of verb stems; and (d) the influence of phonological subregularities in the irregular verbs. Each of these factors is shown to have selective consequences on both successful and erroneous performance in the network. Third, we outline several types of systems which could result in U-shaped acquisition, and discuss the ways in which learning in multi-layered networks can be seen to capture several characteristics of U-shaped learning in children. In general, these models provide information about the role of input in determining the kinds of errors that a network will produce, including the conditions under which rule-like behavior and U-shaped learning will and will not emerge. The results from all simulations are discussed in light of behavioral data on children's acquisition of the past tense and the validity of drawing conclusions about the acquisition of language from models of this sort.

Plunkett K; Marchman V

1991-01-01

48

Critical heat flux prediction by using radial basis function and multilayer perceptron neural networks: A comparison study  

Energy Technology Data Exchange (ETDEWEB)

Critical heat flux (CHF) is an important parameter for the design of nuclear reactors. Although many experimental and theoretical researches have been performed, there is not a single correlation to predict CHF because it is influenced by many parameters. These parameters are based on fixed inlet, local and fixed outlet conditions. Artificial neural networks (ANNs) have been applied to a wide variety of different areas such as prediction, approximation, modeling and classification. In this study, two types of neural networks, radial basis function (RBF) and multilayer perceptron (MLP), are trained with the experimental CHF data and their performances are compared. RBF predicts CHF with root mean square (RMS) errors of 0.24%, 7.9%, 0.16% and MLP predicts CHF with RMS errors of 1.29%, 8.31% and 2.71%, in fixed inlet conditions, local conditions and fixed outlet conditions, respectively. The results show that neural networks with RBF structure have superior performance in CHF data prediction over MLP neural networks. The parametric trends of CHF obtained by the trained ANNs are also evaluated and results reported.

Vaziri, Nima [Department of Physics, Islamic Azad University, Karaj Branch, Moazen Blvd., Rajaee shahr (Iran, Islamic Republic of)]. E-mail: n.vaziri@gmail.com; Hojabri, Alireza [Department of Physics, Islamic Azad University, Karaj Branch, Moazen Blvd., Rajaee shahr (Iran, Islamic Republic of); Erfani, Ali [Department of Physics, Islamic Azad University, Karaj Branch, Moazen Blvd., Rajaee shahr (Iran, Islamic Republic of); Monsefi, Mehrdad [Department of Physics, Islamic Azad University, Karaj Branch, Moazen Blvd., Rajaee shahr (Iran, Islamic Republic of); Nilforooshan, Behnam [Department of Physics, Islamic Azad University, Karaj Branch, Moazen Blvd., Rajaee shahr (Iran, Islamic Republic of)

2007-02-15

49

Application of Multi-Layered Perceptron Neural network (MLPNN) to Combined Economic and Emission Dispatch  

Directory of Open Access Journals (Sweden)

Full Text Available This paper presents a multi-layered perceptronneural network (MLPNN) method to solve the combinedeconomic and emission dispatch (CEED) problem. The harmfulecological effects caused by the emission of particulate andgaseous pollutants like sulfur dioxide (SO2) and oxides ofnitrogen ( NOx ) can be reduced by adequate distribution ofload between the plants of a power system. However, this leadsto a noticeable increase in the operating cost of the plants. Thispaper presents the (MLPNN) method applied for the successfuloperation of the power system subject to economical andenvironmental constraints. The proposed MLP NN method istested for a three plant thermal power system and the results arecompared with the solutions obtained from the classical lambdaiterative technique and simple genetic algorithm (SGA) refinedgenetic algorithm (RGA) method.

Sarakhs branch; Sarakhs, Iran.

2012-01-01

50

Data Optimization with Multilayer Perceptron Neural Network and Using New Pattern in Decision Tree Comparatively  

Directory of Open Access Journals (Sweden)

Full Text Available Problem statement: The aim of the present study is to exemplify the use of Artificial Neural Networks (ANN) for parameter prediction. Missing value or unreal approach to some questions in scale is a problem for unbiased findings. To learn a real pattern with ANN provides robust and unbiased parameter estimation. Approach: To this end, data was collected from 906 students using ?Scale of student views about the expected situations and the current expectations from their families during learning process? for the study entitled ?Student views about the expected situations and the current expectations from their families during learning process?. In the study, first the initial data set gathered using the measurement tool and the new data set produced by Multi-Layer Receptors algorithm, which was considered as the highest predictive level of ANN for the research were individually analyzed by Chaid analysis and the results of the two analyses were compared. Results: The findings showed that as a result of Chaid analysis with the initial data set the variable ?education level of mother? had a considerable effect on total score dependent variable, while ?education level of father? was the influential variable on the attitude level in the data set predicted by ANN, unlike the previous model. Conclusion/Recommendations: The findings of the research show Artificial Neural Networks could be used for parameter estimation in cause-effect based studies. It is also thought the research will contribute to extensive use of advanced statistical methods.

Murat Kayri; Omay Cokluk

2010-01-01

51

Performance comparison between Logistic regression, decision trees, and multilayer perceptron in predicting peripheral neuropathy in type 2 diabetes mellitus.  

UK PubMed Central (United Kingdom)

BACKGROUND: Various methods can be applied to build predictive models for the clinical data with binary outcome variable. This research aims to explore the process of constructing common predictive models, Logistic regression (LR), decision tree (DT) and multilayer perceptron (MLP), as well as focus on specific details when applying the methods mentioned above: what preconditions should be satisfied, how to set parameters of the model, how to screen variables and build accuracy models quickly and efficiently, and how to assess the generalization ability (that is, prediction performance) reliably by Monte Carlo method in the case of small sample size. METHODS: All the 274 patients (include 137 type 2 diabetes mellitus with diabetic peripheral neuropathy and 137 type 2 diabetes mellitus without diabetic peripheral neuropathy) from the Metabolic Disease Hospital in Tianjin participated in the study. There were 30 variables such as sex, age, glycosylated hemoglobin, etc. On account of small sample size, the classification and regression tree (CART) with the chi-squared automatic interaction detector tree (CHAID) were combined by means of the 100 times 5-7 fold stratified cross-validation to build DT. The MLP was constructed by Schwarz Bayes Criterion to choose the number of hidden layers and hidden layer units, alone with levenberg-marquardt (L-M) optimization algorithm, weight decay and preliminary training method. Subsequently, LR was applied by the best subset method with the Akaike Information Criterion (AIC) to make the best used of information and avoid overfitting. Eventually, a 10 to 100 times 3-10 fold stratified cross-validation method was used to compare the generalization ability of DT, MLP and LR in view of the areas under the receiver operating characteristic (ROC) curves (AUC). RESULTS: The AUC of DT, MLP and LR were 0.8863, 0.8536 and 0.8802, respectively. As the larger the AUC of a specific prediction model is, the higher diagnostic ability presents, MLP performed optimally, and then followed by LR and DT in terms of 10-100 times 2-10 fold stratified cross-validation in our study. Neural network model is a preferred option for the data. However, the best subset of multiple LR would be a better choice in view of efficiency and accuracy. CONCLUSION: When dealing with data from small size sample, multiple independent variables and a dichotomous outcome variable, more strategies and statistical techniques (such as AIC criteria, L-M optimization algorithm, the best subset, etc.) should be considered to build a forecast model and some available methods (such as cross-validation, AUC, etc.) could be used for evaluation.

Li CP; Zhi XY; Ma J; Cui Z; Zhu ZL; Zhang C; Hu LP

2012-03-01

52

Modeling of gamma ray energy-absorption buildup factors for thermoluminescent dosimetric materials using multilayer perceptron neural network : A comparative study  

DEFF Research Database (Denmark)

In this work, multilayered perceptron neural networks (MLPNNs) were presented for the computation of the gamma-ray energy absorption buildup factors (BA) of seven thermoluminescent dosimetric (TLD) materials [LiF, BeO, Na2B4O7, CaSO4, Li2B4O7, KMgF3, Ca3(PO4)2] in the energy region 0.015–15MeV, and for penetration depths up to 10 mfp (mean-free-path). The MLPNNs have been trained by a Levenberg–Marquardt learning algorithm. The developed model is in 99% agreement with the ANSI/ANS-6.4.3 standard data set. Furthermore, the model is fast and does not require tremendous computational efforts. The estimated BA data for TLD materials have been given with penetration depth and incident photon energy as comparative to the results of the interpolation method using the Geometrical Progression (G-P) fitting formula.

Kucuk, Nil; Manohara, S.R.

2013-01-01

53

Gas sensors characterization and multilayer perceptron (MLP) hardware implementation for gas identification using a Field Programmable Gate Array (FPGA).  

Science.gov (United States)

This paper develops a primitive gas recognition system for discriminating between industrial gas species. The system under investigation consists of an array of eight micro-hotplate-based SnO2 thin film gas sensors with different selectivity patterns. The output signals are processed through a signal conditioning and analyzing system. These signals feed a decision-making classifier, which is obtained via a Field Programmable Gate Array (FPGA) with Very High-Speed Integrated Circuit Hardware Description Language. The classifier relies on a multilayer neural network based on a back propagation algorithm with one hidden layer of four neurons and eight neurons at the input and five neurons at the output. The neural network designed after implementation consists of twenty thousand gates. The achieved experimental results seem to show the effectiveness of the proposed classifier, which can discriminate between five industrial gases. PMID:23529119

Benrekia, Fayçal; Attari, Mokhtar; Bouhedda, Mounir

2013-03-01

54

Gas sensors characterization and multilayer perceptron (MLP) hardware implementation for gas identification using a Field Programmable Gate Array (FPGA).  

UK PubMed Central (United Kingdom)

This paper develops a primitive gas recognition system for discriminating between industrial gas species. The system under investigation consists of an array of eight micro-hotplate-based SnO2 thin film gas sensors with different selectivity patterns. The output signals are processed through a signal conditioning and analyzing system. These signals feed a decision-making classifier, which is obtained via a Field Programmable Gate Array (FPGA) with Very High-Speed Integrated Circuit Hardware Description Language. The classifier relies on a multilayer neural network based on a back propagation algorithm with one hidden layer of four neurons and eight neurons at the input and five neurons at the output. The neural network designed after implementation consists of twenty thousand gates. The achieved experimental results seem to show the effectiveness of the proposed classifier, which can discriminate between five industrial gases.

Benrekia F; Attari M; Bouhedda M

2013-01-01

55

Gas Sensors Characterization and Multilayer Perceptron (MLP) Hardware Implementation for Gas Identification Using a Field Programmable Gate Array (FPGA)  

Directory of Open Access Journals (Sweden)

Full Text Available This paper develops a primitive gas recognition system for discriminating between industrial gas species. The system under investigation consists of an array of eight micro-hotplate-based SnO2 thin film gas sensors with different selectivity patterns. The output signals are processed through a signal conditioning and analyzing system. These signals feed a decision-making classifier, which is obtained via a Field Programmable Gate Array (FPGA) with Very High-Speed Integrated Circuit Hardware Description Language. The classifier relies on a multilayer neural network based on a back propagation algorithm with one hidden layer of four neurons and eight neurons at the input and five neurons at the output. The neural network designed after implementation consists of twenty thousand gates. The achieved experimental results seem to show the effectiveness of the proposed classifier, which can discriminate between five industrial gases.

Fayçal Benrekia; Mokhtar Attari; Mounir Bouhedda

2013-01-01

56

Optimization of metformin HCl 500 mg sustained release matrix tablets using Artificial Neural Network (ANN) based on Multilayer Perceptrons (MLP) model.  

UK PubMed Central (United Kingdom)

The aim of the present study was to apply the simultaneous optimization method incorporating Artificial Neural Network (ANN) using Multi-layer Perceptron (MLP) model to the development of a metformin HCl 500 mg sustained release matrix tablets with an optimized in vitro release profile. The amounts of HPMC K15M and PVP K30 at three levels (-1, 0, +1) for each were selected as casual factors. In vitro dissolution time profiles at four different sampling times (1 h, 2 h, 4 h and 8 h) were chosen as output variables. 13 kinds of metformin matrix tablets were prepared according to a 2(3) factorial design (central composite) with five extra center points, and their dissolution tests were performed. Commercially available STATISTICA Neural Network software (Stat Soft, Inc., Tulsa, OK, U.S.A.) was used throughout the study. The training process of MLP was completed until a satisfactory value of root square mean (RSM) for the test data was obtained using feed forward back propagation method. The root mean square value for the trained network was 0.000097, which indicated that the optimal MLP model was reached. The optimal tablet formulation based on some predetermined release criteria predicted by MLP was 336 mg of HPMC K15M and 130 mg of PVP K30. Calculated difference (f(1) 2.19) and similarity (f(2) 89.79) factors indicated that there was no difference between predicted and experimentally observed drug release profiles for the optimal formulation. This work illustrates the potential for an artificial neural network with MLP, to assist in development of sustained release dosage forms.

Mandal U; Gowda V; Ghosh A; Bose A; Bhaumik U; Chatterjee B; Pal TK

2008-02-01

57

Optimization of metformin HCl 500 mg sustained release matrix tablets using Artificial Neural Network (ANN) based on Multilayer Perceptrons (MLP) model.  

Science.gov (United States)

The aim of the present study was to apply the simultaneous optimization method incorporating Artificial Neural Network (ANN) using Multi-layer Perceptron (MLP) model to the development of a metformin HCl 500 mg sustained release matrix tablets with an optimized in vitro release profile. The amounts of HPMC K15M and PVP K30 at three levels (-1, 0, +1) for each were selected as casual factors. In vitro dissolution time profiles at four different sampling times (1 h, 2 h, 4 h and 8 h) were chosen as output variables. 13 kinds of metformin matrix tablets were prepared according to a 2(3) factorial design (central composite) with five extra center points, and their dissolution tests were performed. Commercially available STATISTICA Neural Network software (Stat Soft, Inc., Tulsa, OK, U.S.A.) was used throughout the study. The training process of MLP was completed until a satisfactory value of root square mean (RSM) for the test data was obtained using feed forward back propagation method. The root mean square value for the trained network was 0.000097, which indicated that the optimal MLP model was reached. The optimal tablet formulation based on some predetermined release criteria predicted by MLP was 336 mg of HPMC K15M and 130 mg of PVP K30. Calculated difference (f(1) 2.19) and similarity (f(2) 89.79) factors indicated that there was no difference between predicted and experimentally observed drug release profiles for the optimal formulation. This work illustrates the potential for an artificial neural network with MLP, to assist in development of sustained release dosage forms. PMID:18239298

Mandal, Uttam; Gowda, Veeran; Ghosh, Animesh; Bose, Anirbandeep; Bhaumik, Uttam; Chatterjee, Bappaditya; Pal, Tapan Kumar

2008-02-01

58

Multilayer perceptron classification of unknown volatile chemicals from the firing rates of insect olfactory sensory neurons and its application to biosensor design.  

UK PubMed Central (United Kingdom)

In this letter, we use the firing rates from an array of olfactory sensory neurons (OSNs) of the fruit fly, Drosophila melanogaster, to train an artificial neural network (ANN) to distinguish different chemical classes of volatile odorants. Bootstrapping is implemented for the optimized networks, providing an accurate estimate of a network's predicted values. Initially a simple linear predictor was used to assess the complexity of the data and was found to provide low prediction performance. A nonlinear ANN in the form of a single multilayer perceptron (MLP) was also used, providing a significant increase in prediction performance. The effect of the number of hidden layers and hidden neurons of the MLP was investigated and found to be effective in enhancing network performance with both a single and a double hidden layer investigated separately. A hybrid array of MLPs was investigated and compared against the single MLP architecture. The hybrid MLPs were found to classify all vectors of the validation set, presenting the highest degree of prediction accuracy. Adjustment of the number of hidden neurons was investigated, providing further performance gain. In addition, noise injection was investigated, proving successful for certain network designs. It was found that the best-performing MLP was that of the double-hidden-layer hybrid MLP network without the use of noise injection. Furthermore, the level of performance was examined when different numbers of OSNs used were varied from the maximum of 24 to only 5 OSNs. Finally, the ideal OSNs were identified that optimized network performance. The results obtained from this study provide strong evidence of the usefulness of ANNs in the field of olfaction for the future realization of a signal processing back end for an artificial olfactory biosensor.

Bachtiar LR; Unsworth CP; Newcomb RD; Crampin EJ

2013-01-01

59

Compact yet efficient hardware architecture for multilayer-perceptron neural networks/ Arquitetura de hardware compacta e eficiente para redes neurais artificiais do tipo múltiplas camadas  

Scientific Electronic Library Online (English)

Full Text Available Abstract in portuguese Em termos computacionais, uma rede neural artificial (RNA) pode ser implementada em software ou em hardware, ou ainda de maneira híbrida, combinando ambos os recursos. O presente trabalho propõe uma arquitetura de hardware para a computação de uma rede neural do tipo perceptron com múltiplas camadas (MLP). Soluções em hardware tendem a ser mais eficientes do que soluções em software. O projeto em questão, além de explorar fortemente o paralelismo das redes neur (more) ais, permite alterações do número de entradas, número de camadas e de neurônios por camada, de modo que diversas aplicações de RNAs possam ser executadas no hardware proposto. Visando a uma redução de tempo do processamento aritmético, um número real é aproximado por uma fração de inteiros. Dessa forma, as operações aritméticas limitam-se a operações inteiras, executadas por circuitos combinacionais. Uma simples máquina de estados é demandada para controlar somas e produtos de frações. A função de ativação usada neste projeto é a sigmóide. Essa função é aproximada mediante o uso de polinômios, cujas operações são regidas por somas e produtos. Um teorema é introduzido e provado, permitindo a fundamentação da estratégia de cálculo da função de ativação. Dessa forma, reaproveita-se o circuito aritmético da soma ponderada para também computar a sigmóide. Essa re-utilização dos recursos levou a uma redução drástica de área total de circuito. Após modelagem e simulação para validação do bom funcionamento, a arquitetura proposta foi sintetizada utilizando recursos reconfiguráveis, do tipo FPGA. Os resultados são promissores. Abstract in english There are several neural network implementations using either software, hardware-based or a hardware/software co-design. This work proposes a hardware architecture to implement an artificial neural network (ANN), whose topology is the multilayer perceptron (MLP). In this paper, we explore the parallelism of neural networks and allow on-thefly changes of the number of inputs, number of layers and number of neurons per layer of the net. This reconfigurability characteristic (more) permits that any application of ANNs may be implemented using the proposed hardware. In order to reduce the processing time that is spent in arithmetic computation, a real number is represented using a fraction of integers. In this way, the arithmetics is limited to integer operations, performed by fast combinational circuits. A simple state machine is required to control sums and products of fractions. Sigmoid is used as the activation function in the proposed implementation. It is approximated by polynomials, whose underlying computation requires only sums and products. A theorem is introduced and proven so as to cover the arithmetic strategy of the computation of the activation function. Thus, the arithmetic circuitry used to implement the neuron weighted sum is reused for computing the sigmoid. this resource sharing decreased drastically the total area of the system. After modeling and simulation for functionality validation, the proposed architecture synthesized using reconfigurable hardware. The results are promising.

Silva, Rodrigo Martins da; Mourelle, Luiza de Macedo; Nedjah, Nadia

2011-12-01

60

El uso de perceptrones multicapa para la modelización estadística de series de tiempo no lineales de so2, en Salta Capital, Argentina/ The use of multilayer perceptrons for statistical modeling so2 non linear time series in Salta Capital, Argentina  

Scientific Electronic Library Online (English)

Full Text Available Abstract in spanish En este trabajo se realizó un estudio estadístico de variables físico químicas asociadas al fenómeno de contaminación ambiental, en particular concentración media mensual de SO2 , medidas en la ciudad Salta Capital, Argentina, simultáneamente a concentraciones de NO2 y O3 . Las series bajo estudio presentaban comportamientos dinámicos no lineales, datos atípicos y cambios estructurales, lo que hizo imposible modelarlas con tipologías econométricas tradiciones (more) (AR, MA, ARMA, ARIMA, entre otras). Una solución eficiente que se encontró, hace uso de la teoría de los perceptrones multicapa. Mediante el modelo estructural de series de tiempo, esta solución se presenta como un proceso matemático iterativo que permite obtener un modelado final el cual tiene una muy alta confiabilidad (95%), para realizar pronoósticos a futuro sobre el comportamiento de la variable estudiada. Abstract in english In this paper a statistical study of phisical-chemistry variables connected with enviroment pollution, specifically SO2 monthly average concentration, measured in Salta Capital city, Argentina, together with NO2 and O3 concentrations, was made. Time series under study shown non linear dinamic behaviour, outliers and structural changes. Due to these it was impossible to use typical econometric typologies (AR, MA, ARMA, ARIMA, among others). An effective solution which uses (more) multistep perceptrons theory was found. By using structural time series modelling, this solution is presented by an iterative mathematical process that allows us to obtain a final model with a high confidence level (95%) in order to do the forecasting step on the studied variable.

Musso, Haydeé Elena; Ávila Blas, Orlando José

2013-01-01

 
 
 
 
61

One step ahead forecasting using Multilayered perceptron  

UK PubMed Central (United Kingdom)

When dealing with time series, the one step ahead forecasting problembased on experimental data is the problem of estimating the autoregressionfunction of the underlying process. When minimizing the expected forecastingerror is the main goal the flexible approach has to be used to be able toadjust the complexity of the model to the complexity of the data. Multilayeredperceptrons are a popular example of such a flexible approach but notthe only one. Other methods such as kernel approximator (e.g. NaradayaWatson regressor), regression spline or wavelet regressor can also be used.But whatever flexible approach is, the main issue remains the control of thecomplexity of the flexible approximator. Noise injection in the inputs is anefficient technique to do so. The complexity of the regessor is then adjustedthanks to the quantity (variance) of injected noise. This quantity is tunedusing a bootstrap estimation of the forecasting error. One unexpected effectof this ap...

Yves Gr; Xia Ding; Centre De Recherches De Royallieu

62

The Perceptron with Dynamic Margin  

CERN Document Server

The classical perceptron rule provides a varying upper bound on the maximum margin, namely the length of the current weight vector divided by the total number of updates up to that time. Requiring that the perceptron updates its internal state whenever the normalized margin of a pattern is found not to exceed a certain fraction of this dynamic upper bound we construct a new approximate maximum margin classifier called the perceptron with dynamic margin (PDM). We demonstrate that PDM converges in a finite number of steps and derive an upper bound on them. We also compare experimentally PDM with other perceptron-like algorithms and support vector machines on hard margin tasks involving linear kernels which are equivalent to 2-norm soft margin.

Panagiotakopoulos, Constantinos

2011-01-01

63

Generalization ability of a perceptron with nonmonotonic transfer function  

Science.gov (United States)

We investigate the generalization ability of a perceptron with nonmonotonic transfer function of a reversed-wedge type in on-line mode. This network is identical to a parity machine, a multilayer network. We consider several learning algorithms. By the perceptron algorithm the generalization error is shown to decrease by the ?-1/3-law similarly to the case of a simple perceptron in a restricted range of the parameter a characterizing the nonmonotonic transfer function. For other values of a, the perceptron algorithm leads to the state where the weight vector of the student is just opposite to that of the teacher. The Hebbian learning algorithm has a similar property; it works only in a limited range of the parameter. The conventional AdaTron algorithm does not give a vanishing generalization error for any values of a. We thus introduce a modified AdaTron algorithm that yields a good performance for all values of a. We also investigate the effects of optimization of the learning rate as well as of the learning algorithm. Both methods give excellent learning curves proportional to ?-1. The latter optimization is related to the Bayes statistics and is shown to yield useful hints to extract maximum amount of information necessary to accelerate learning processes.

Inoue, Jun-Ichi; Nishimori, Hidetoshi; Kabashima, Yoshiyuki

1998-07-01

64

Ranking and Reranking with Perceptron  

UK PubMed Central (United Kingdom)

This work is inspired by the so-called reranking tasks in natural language processing.In this paper, we first study the ranking, reranking, and ordinal regression algorithmsproposed recently in the context of ranks and margins. Then we propose a general frameworkfor ranking and reranking, and introduce a series of variants of the perceptron algorithm forranking and reranking in the new framework. Compared to the approach of using pairwiseobjects as training samples, the new algorithms reduces the data complexity and trainingtime. We apply the new perceptron algorithms to the parse reranking and machine translationreranking tasks, and study the performance of reranking by employing various definitions ofthe margins.

Libin Shen; Aravind K. Joshi

65

A Second-Order Perceptron Algorithm  

UK PubMed Central (United Kingdom)

We introduce a variant of the Perceptron algorithm called second-order Perceptron algorithm, which is able to exploit certain spectral properties of the data. We analyze the second-order Perceptron algorithm in the mistake bound model of on-line learning and prove bounds in terms of the eigenvalues of the Gram matrix created from the data.

Alex Conconi; Claudio Gentile

66

a Statistical-Fuzzy Perceptron  

Science.gov (United States)

An optimal statistical perceptron algorithm is derived using the Bayes classification theory. The described algorithm is able to construct an optimal classification hyperplane for separable and nonseparable classes. The described algorithm can be easily improved by imposing a simple fuzzyfication scheme of the training sets.

Andrecut, M.

67

ERROR VS REJECTION CURVE FOR THE PERCEPTRON  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We calculate the generalization error epsilon for a > perceptron J, trained by a teacher perceptron T, on input patterns S that form a fixed angle arccos (J.S) with the student. We show that the error is reduced from a power law to an exponentially fast decay by rejecting input patterns th...

PARRONDO, JMR; VAN DEN BROECK, Christian

68

Recurrent neural networks for diagnosis of carpal tunnel syndrome using electrophysiologic findings.  

UK PubMed Central (United Kingdom)

This paper presents the use of recurrent neural networks (RNNs) for diagnosis of carpal tunnel syndrome (CTS) (normal, right CTS, left CTS, bilateral CTS). The RNN is trained with the Levenberg-Marquardt algorithm. The RNN is trained on the features of CTS (right median motor latency, left median motor latency, right median sensory latency, left median sensory latency). The multilayer perceptron neural network (MLPNN) is also implemented for comparison the performance of the classifiers on the same diagnosis problem. The total classification accuracy of the RNN is significantly high (94.80%). The obtained results confirmed the validity of the RNNs to help in clinical decision-making.

Ilbay K; Ubeyli ED; Ilbay G; Budak F

2010-08-01

69

Optimization of High Order Perceptrons  

UK PubMed Central (United Kingdom)

Neural networks are widely applied in research and industry. However, their broader applicationis hampered by various technical details. Among these details are several trainingparameters and the choice of the topology of the network. The subject of this dissertation istherefore the elimination and determination of usually user specified learning parameters.Furthermore, suitable application domains for neural networks are discussed.Among all training parameters, special attention is given to the learning rate, the gainof the sigmoidal function, and the initial weight range. A theorem is proven which permitsthe elimination of one of these parameters. Furthermore, it is shown that for high orderperceptrons, very small random initial weights are usually optimal in terms of training timeand generalization.Another important problem in the application of neural networks is to find a networktopology that suits a given data set. This favors high order perceptrons over several other...

Georg Thimm; Prof M. Kunt; Prof C. Pelligrini; Prof W. Gerstner; Prof L. C. Jain; E. Fiesler (ph. D

70

Online learning in a chemical perceptron.  

UK PubMed Central (United Kingdom)

Autonomous learning implemented purely by means of a synthetic chemical system has not been previously realized. Learning promotes reusability and minimizes the system design to simple input-output specification. In this article we introduce a chemical perceptron, the first full-featured implementation of a perceptron in an artificial (simulated) chemistry. A perceptron is the simplest system capable of learning, inspired by the functioning of a biological neuron. Our artificial chemistry is deterministic and discrete-time, and follows Michaelis-Menten kinetics. We present two models, the weight-loop perceptron and the weight-race perceptron, which represent two possible strategies for a chemical implementation of linear integration and threshold. Both chemical perceptrons can successfully identify all 14 linearly separable two-input logic functions and maintain high robustness against rate-constant perturbations. We suggest that DNA strand displacement could, in principle, provide an implementation substrate for our model, allowing the chemical perceptron to perform reusable, programmable, and adaptable wet biochemical computing.

Banda P; Teuscher C; Lakin MR

2013-01-01

71

The Margitron: A Generalised Perceptron with Margin  

CERN Document Server

We identify the classical Perceptron algorithm with margin as a member of a broader family of large margin classifiers which we collectively call the Margitron. The Margitron, (despite its) sharing the same update rule with the Perceptron, is shown in an incremental setting to converge in a finite number of updates to solutions possessing any desirable fraction of the maximum margin. Experiments comparing the Margitron with decomposition SVMs on tasks involving linear kernels and 2-norm soft margin are also reported.

Panagiotakopoulos, Constantinos

2008-01-01

72

Dynamical optimization of the perceptron structure  

International Nuclear Information System (INIS)

A complex method of the perceptron structure dynamic optimization is proposed. This method consists of two parts: the reduction of the input data dimension by means of a recirculative neural network and dynamic restructuring of the perceptron, as well as its structure optimization. The latter is realized by applying two dynamic procedures: adding new and removing faint neurons from network. This method was approved by applying it to a medical problem and demonstrated acceptable results. (author)

2002-01-01

73

On PAC Learning Using Winnow, Perceptron, and a Perceptron-Like Algorithm  

UK PubMed Central (United Kingdom)

In this paper we analyze the PAC learning abilitiesof several simple iterative algorithms for learninglinear threshold functions, obtaining both positiveand negative results. We show that Littlestone'sWinnow algorithm is not an efficient PAC learningalgorithm for the class of positive linear thresholdfunctions. We also prove that the Perceptron algorithmcannot efficiently learn the unrestricted classof linear threshold functions even under the uniformdistribution on boolean examples. However,we show that the Perceptron algorithm can efficientlyPAC learn the class of nested functions (aconcept class known to be hard for Perceptron underarbitrary distributions) under the uniform distributionon boolean examples. Finally, we givea very simple Perceptron-like algorithm for learningorigin-centered halfspaces under the uniformdistribution on the unit sphere in Rn: Unlike thePerceptron algorithm, which cannot learn in thepresence of classification nois...

Rocco A. Servedio

74

Parallel strategy for optimal learning in perceptrons  

International Nuclear Information System (INIS)

We developed a parallel strategy for learning optimally specific realizable rules by perceptrons, in an online learning scenario. Our result is a generalization of the Caticha-Kinouchi (CK) algorithm developed for learning a perceptron with a synaptic vector drawn from a uniform distribution over the N-dimensional sphere, so called the typical case. Our method outperforms the CK algorithm in almost all possible situations, failing only in a denumerable set of cases. The algorithm is optimal in the sense that it saturates Bayesian bounds when it succeeds.

2010-03-26

75

The margitron: a generalized perceptron with margin.  

UK PubMed Central (United Kingdom)

We identify the classical perceptron algorithm with margin as a member of a broader family of large margin classifiers, which we collectively call the margitron. The margitron, (despite its) sharing the same update rule with the perceptron, is shown in an incremental setting to converge in a finite number of updates to solutions possessing any desirable fraction of the maximum margin. We also report on experiments comparing the margitron with decomposition support vector machines, cutting-plane algorithms, and gradient descent methods on hard margin tasks involving linear kernels which are equivalent to 2-norm soft margin. Our results suggest that the margitron is very competitive.

Panagiotakopoulos C; Tsampouka P

2011-03-01

76

The margitron: a generalized perceptron with margin.  

Science.gov (United States)

We identify the classical perceptron algorithm with margin as a member of a broader family of large margin classifiers, which we collectively call the margitron. The margitron, (despite its) sharing the same update rule with the perceptron, is shown in an incremental setting to converge in a finite number of updates to solutions possessing any desirable fraction of the maximum margin. We also report on experiments comparing the margitron with decomposition support vector machines, cutting-plane algorithms, and gradient descent methods on hard margin tasks involving linear kernels which are equivalent to 2-norm soft margin. Our results suggest that the margitron is very competitive. PMID:21216709

Panagiotakopoulos, Constantinos; Tsampouka, Petroula

2011-01-06

77

FPGA Implementation of Multilayer Perceptron for Modeling of Photovoltaic panel  

International Nuclear Information System (INIS)

The Number of electronic applications using artificial neural network-based solutions has increased considerably in the last few years. However, their applications in photovoltaic systems are very limited. This paper introduces the preliminary result of the modeling and simulation of photovoltaic panel based on neural network and VHDL-language. In fact, an experimental database of meteorological data (irradiation, temperature) and output electrical generation signals of the PV-panel (current and voltage) has been used in this study. The inputs of the ANN-PV-panel are the daily total irradiation and mean average temperature while the outputs are the current and voltage generated from the panel. Firstly, a dataset of 4x364 have been used for training the network. Subsequently, the neural network (MLP) corresponding to PV-panel is simulated using VHDL language based on the saved weights and bias of the network. Simulation results of the trained MLP-PV panel based on Matlab and VHDL are presented. The proposed PV-panel model based ANN and VHDL permit to evaluate the performance PV-panel using only the environmental factors and involves less computational efforts, and it can be used for predicting the output electrical energy from the PV-panel.

2008-06-12

78

Multifractal analysis of perceptron learning with errors  

CERN Multimedia

Random input patterns induce a partition of the coupling space of a perceptron into cells labeled by their output sequences. Learning some data with a maximal error rate leads to clusters of neighboring cells. By analyzing the internal structure of these clusters with the formalism of multifractals, we can handle different storage and generalization tasks for lazy students and absent-minded teachers within one unified approach. The results also allow some conclusions on the spatial distribution of cells.

Weigt, M

1998-01-01

79

Incorporating fuzzy membership functions into the perceptron algorithm.  

UK PubMed Central (United Kingdom)

The perceptron algorithm, one of the class of gradient descent techniques, has been widely used in pattern recognition to determine linear decision boundaries. While this algorithm is guaranteed to converge to a separating hyperplane if the data are linearly separable, it exhibits erratic behavior if the data are not linearly separable. Fuzzy set theory is introduced into the perceptron algorithm to produce a ``fuzzy algorithm'' which ameliorates the convergence problem in the nonseparable case. It is shown that the fuzzy perceptron, like its crisp counterpart, converges in the separable case. A method of generating membership functions is developed, and experimental results comparing the crisp to the fuzzy perceptron are presented.

Keller JM; Hunt DJ

1985-06-01

80

Incorporating fuzzy membership functions into the perceptron algorithm.  

Science.gov (United States)

The perceptron algorithm, one of the class of gradient descent techniques, has been widely used in pattern recognition to determine linear decision boundaries. While this algorithm is guaranteed to converge to a separating hyperplane if the data are linearly separable, it exhibits erratic behavior if the data are not linearly separable. Fuzzy set theory is introduced into the perceptron algorithm to produce a ``fuzzy algorithm'' which ameliorates the convergence problem in the nonseparable case. It is shown that the fuzzy perceptron, like its crisp counterpart, converges in the separable case. A method of generating membership functions is developed, and experimental results comparing the crisp to the fuzzy perceptron are presented. PMID:21869307

Keller, J M; Hunt, D J

1985-06-01

 
 
 
 
81

Large Margin Classification Using the Perceptron Algorithm  

UK PubMed Central (United Kingdom)

We introduce and analyze a new algorithm for linear classification which combines Rosenblatt's perceptron algorithm with Helmbold and Warmuth's leave-one-out method. Like Vapnik's maximal-margin classifier, our algorithm takes advantage of data that are linearly separablewith large margins. Compared to Vapnik's algorithm, however, ours is much simplerto implement, and much more efficient in terms of computation time. We also show that ouralgorithm can be efficiently used in very high dimensional spaces using kernel functions. Weperformed some experiments using our algorithm, and some variants of it, for classifying imagesof handwritten digits. The performance of our algorithm is close to, but not as good as, theperformance of maximal-margin classifiers on the same problem, while saving significantly oncomputation time and programming effort.1 IntroductionOne of the most influential developments in the theory of machine learning in the last few yearsis Vapnik's work on supp...

Yoav Freund; Robert E. Schapire

82

Learning from correlated patterns by simple perceptrons  

Energy Technology Data Exchange (ETDEWEB)

Learning behavior of simple perceptrons is analyzed for a teacher-student scenario in which output labels are provided by a teacher network for a set of possibly correlated input patterns, and such that the teacher and student networks are of the same type. Our main concern is the effect of statistical correlations among the input patterns on learning performance. For this purpose, we extend to the teacher-student scenario a methodology for analyzing randomly labeled patterns recently developed in Shinzato and Kabashima 2008 J. Phys. A: Math. Theor. 41 324013. This methodology is used for analyzing situations in which orthogonality of the input patterns is enhanced in order to optimize the learning performance.

Shinzato, Takashi; Kabashima, Yoshiyuki [Department of Computational Intelligence and Systems Science, Tokyo Institute of Technology, Yokohama 226-8502 (Japan)], E-mail: shinzato@sp.dis.titech.ac.jp, E-mail: kaba@dis.titech.ac.jp

2009-01-09

83

Statistical Mechanics of Node-Perturbation Learning for Nonlinear Perceptron  

Science.gov (United States)

Node-perturbation learning is a type of statistical gradient descent algorithm that can be applied to problems where the objective function is not explicitly formulated, including reinforcement learning. Node-perturbation learning with M linear perceptrons has previously been analyzed using the methods of statistical mechanics. It was shown that cross-talk noise, which originates from the error of the other outputs, increases the generalization error as the number of outputs increases. On the other hand, a nonlinear perceptron has several advantages over a linear perceptron, such as the ability to use nonlinear outputs, learnability, storage capacity, and so forth. However, node-perturbation for a nonlinear perceptron has yet to be analyzed theoretically. In this paper, we derive a learning rule of node-perturbation learning for a nonlinear perceptron within the framework of REINFORCE learning and analyze the learning behavior by using statistical mechanical methods. From the results, we found that the signal and cross-talk terms of the order parameter Q have different forms for a nonlinear perceptron. Moreover, the increase in the generalization error with increasing number of outputs is less than for a linear perceptron.

Hara, Kazuyuki; Katahira, Kentaro; Okanoya, Kazuo; Okada, Masato

2013-05-01

84

Growing Layers of Perceptrons: Introducing the Extentron Algorithm  

UK PubMed Central (United Kingdom)

The ideas presented here are based on two observationsof perceptrons: (1) when the perceptronlearning algorithm cycles among hyperplanes, thehyperplanes may be compared to select one thatgives a best split of the examples, and (2) it is alwayspossible for the perceptron to build a hyperplanethat separates at least one example from allthe rest. We describe the Extentron which growsmulti-layer networks capable of distinguishing nonlinearly-separable data using the simple perceptronrule for linear threshold units. The resulting algorithmis simple, very fast, scales well to large problems,retains the convergence properties of the perceptron,and can be completely specified using onlytwo parameters. Results are presented comparingthe Extentron to other neural network paradigmsand to symbolic learning systems.1 IntroductionIt is well known that the simple perceptron algorithm(Rosenblatt, 1958) is unable to represent classificationswhich are not linearly separable (Minsky...

Paul T. Baffes; John M. Zelle

85

Selective Voting for Perceptron-like Online Learning  

UK PubMed Central (United Kingdom)

The voting technique, which combines the predictions of several classifiers, can improve the generalization performance significantly by increasing the fraction of training examples with large margins. ROMMA (the Relaxed Online Maximum Margin Algorithm) is a perceptron-like online learning algorithm to approximate the optimal margin classifier, and aggressive ROMMA updates its prediction vectors whenever the output produced by the current prediction vector does not exceed the wanted threshold instead of just after a mistake. Alternatively, the voted perceptron algorithm improves the perceptron algorithm significantly based on a conversion from online learning to batch learning. However, the same voting method worsens the performance of aggressive ROMMA. In this paper, we describe a new voting method, called selective voting, for perceptron-like online learning algorithms. We provide theoretical and experimental evidence that selective voting is better than full voting, and the performance...

Yi Li

86

The Curse of Dimensionality and the Perceptron Algorithm  

UK PubMed Central (United Kingdom)

We give an adversary strategy that forces the Perceptron algorithmto make (N Gamma k + 1)=2 mistakes when learning k-literal disjunctions overN variables. Experimentally we see that even for simple random data,the number of mistakes made by the Perceptron algorithm grows almostlinearly with N , even if the number k of relevant variable remains a smallconstant. Thus, the Perceptron algorithm suffers from the curse of dimensionalityeven when the target is extremely simple and almost all ofthe dimensions are irrelevant. In contrast, Littlestone's algorithm Winnowmakes at most O(k log N ) mistakes for the same problem. Both algorithmsuse linear threshold functions as their hypotheses. However, Winnow doesmultiplicative updates to its weight vector instead of the additive updatesof the Perceptron algorithm.Introduction 31 IntroductionThis paper addresses the familiar problem of predicting with a linear thresholdfunction. The instances are N-dimensional real vect...

Jyrki Kivinen; Manfred K. Warmuth

87

A canonical ensemble approach to graded-response perceptrons  

CERN Multimedia

Perceptrons with graded input-output relations and a limited output precision are studied within the Gardner-Derrida canonical ensemble approach. Soft non- negative error measures are introduced allowing for extended retrieval properties. In particular, the performance of these systems for a linear and quadratic error measure, corresponding to the perceptron respectively the adaline learning algorithm, is compared with the performance for a rigid error measure, simply counting the number of errors. Replica-symmetry-breaking effects are evaluated.

Bollé, D

1999-01-01

88

The Perceptron Algorithm: Image and Signal Decomposition, Compression, and Analysis by Iterative Gaussian Blurring  

CERN Multimedia

A novel algorithm for tunable compression to within the precision of reproduction targets, or storage, is proposed. The new algorithm is termed the `Perceptron Algorithm', which utilises simple existing concepts in a novel way, has multiple immediate commercial application aspects as well as it opens up a multitude of fronts in computational science and technology. The aims of this paper are to present the concepts underlying the algorithm, observations by its application to some example cases, and the identification of a multitude of potential areas of applications such as: image compression by orders of magnitude, signal compression including sound as well, image analysis in a multilayered detailed analysis, pattern recognition and matching and rapid database searching (e.g. face recognition), motion analysis, biomedical applications e.g. in MRI and CAT scan image analysis and compression, as well as hints on the link of these ideas to the way how biological memory might work leading to new points of view i...

Vassiliadis, V S

2006-01-01

89

On-line Learning with a Perceptron  

UK PubMed Central (United Kingdom)

We study on--line learning of a linearly separable rule with a simpleperceptron. Training utilizes a sequence of uncorrelated, randomly drawnN--dimensional input examples. In the thermodynamic limit the generalizationerror after training with P such examples can be calculated exactly.For the standard perceptron algorithm it decreases like (N=P )1=3for largeP=N , in contrast to the faster (N=P )1=2--behavior of the so--called Hebbianlearning. Furthermore, we show that a specific parameter--free on--linescheme, the AdaTron algorithm, gives an asymptotic (N=P )--decay of thegeneralization error. This coincides (up to a constant factor) with thebound for any training process based on random examples, including off--line learning. Simulations confirm our results.PACS. 87.10, 02.50, 05.90A very important feature of Feedforward Neural Networks is their ability tolearn a rule from examples [1, 2]. Methods known from Statistical Mechanicshave been successfully used to s...

Michael Biehl; Peter Riegler

90

On--line Learning with a Perceptron  

UK PubMed Central (United Kingdom)

We study on--line learning of a linearly separable rule with a simpleperceptron. Training utilizes a sequence of uncorrelated, randomly drawnN--dimensional input examples. In the thermodynamic limit the generalizationerror after training with P such examples can be calculated exactly.For the standard perceptron algorithm it decreases like (N=P )1=3for largeP=N , in contrast to the faster (N=P )1=2--behavior of the so--called Hebbianlearning. Furthermore, we show that a specific parameter--free on--linescheme, the AdaTron algorithm, gives an asymptotic (N=P )--decay of thegeneralization error. This coincides (up to a constant factor) with thebound for any training process based on random examples, including off--line learning. Simulations confirm our results.PACS. 87.10, 02.50, 05.90A very important feature of Feedforward Neural Networks is their ability tolearn a rule from examples [1, 2]. Methods known from Statistical Mechanicshave been successfully used to s...

Michael Biehl; Peter Riegler

91

Volterra models and three-layer perceptrons.  

Science.gov (United States)

This paper proposes the use of a class of feedforward artificial neural networks with polynomial activation functions (distinct for each hidden unit) for practical modeling of high-order Volterra systems. Discrete-time Volterra models (DVMs) are often used in the study of nonlinear physical and physiological systems using stimulus-response data. However, their practical use has been hindered by computational limitations that confine them to low-order nonlinearities (i.e., only estimation of low-order kernels is practically feasible). Since three-layer perceptrons (TLPs) can be used to represent input-output nonlinear mappings of arbitrary order, this paper explores the basic relations between DVMs and TLPs with tapped-delay inputs in the context of nonlinear system modeling. A variant of TLP with polynomial activation functions-termed "separable Volterra networks" (SVNs)-is found particularly useful in deriving explicit relations with DVM and in obtaining practicable models of highly nonlinear systems from stimulus-response data. The conditions under which the two approaches yield equivalent representations of the input-output relation are explored, and the feasibility of DVM estimation via equivalent SVN training using backpropagation is demonstrated by computer-simulated examples and compared with results from the Laguerre expansion technique (LET). The use of SVN models allows practicable modeling of high-order nonlinear systems, thus removing the main practical limitation of the DVM approach. PMID:18255744

Marmarelis, V Z; Zhao, X

1997-01-01

92

Volterra models and three-layer perceptrons.  

UK PubMed Central (United Kingdom)

This paper proposes the use of a class of feedforward artificial neural networks with polynomial activation functions (distinct for each hidden unit) for practical modeling of high-order Volterra systems. Discrete-time Volterra models (DVMs) are often used in the study of nonlinear physical and physiological systems using stimulus-response data. However, their practical use has been hindered by computational limitations that confine them to low-order nonlinearities (i.e., only estimation of low-order kernels is practically feasible). Since three-layer perceptrons (TLPs) can be used to represent input-output nonlinear mappings of arbitrary order, this paper explores the basic relations between DVMs and TLPs with tapped-delay inputs in the context of nonlinear system modeling. A variant of TLP with polynomial activation functions-termed "separable Volterra networks" (SVNs)-is found particularly useful in deriving explicit relations with DVM and in obtaining practicable models of highly nonlinear systems from stimulus-response data. The conditions under which the two approaches yield equivalent representations of the input-output relation are explored, and the feasibility of DVM estimation via equivalent SVN training using backpropagation is demonstrated by computer-simulated examples and compared with results from the Laguerre expansion technique (LET). The use of SVN models allows practicable modeling of high-order nonlinear systems, thus removing the main practical limitation of the DVM approach.

Marmarelis VZ; Zhao X

1997-01-01

93

An empirical evaluation of the fuzzy kernel perceptron.  

Science.gov (United States)

J.-H. Chen and C.-S. Chen have recently proposed a nonlinear variant of Keller and Hunt's fuzzy perceptron algorithm, based on the now familiar "kernel trick." In this letter, we demonstrate experimentally that J.-H. Chen and C.-S. Chen's assertion that the fuzzy kernel perceptron (FKP) outperforms the support vector machine (SVM) cannot be sustained. A more thorough model comparison exercise, based on a much wider range of benchmark data sets, shows that the FKP algorithm is not competitive with the SVM. PMID:17526361

Cawley, Gavin C

2007-05-01

94

Smoothed Analysis of the Perceptron Algorithm for Linear Programming  

UK PubMed Central (United Kingdom)

The smoothed complexity [1] of an algorithm is the expected running time of the algorithm on an arbitrary instance under a random perturbation. It was shown recently that the simplex algorithm has polynomial smoothed complexity. We show that a simple greedy algorithm for linear programming, the Perceptron algorithm, also has polynomial smoothed complexity, in a high probability sense: that is, the running time is polynomial with high probability over the random perturbation. While the bounds are not strictly comparable, for many choices of parameters the running time bound we show here for the Perceptron algorithm is much lower than the bound given in [1] for the Simplex algorithm.

Avrim Blum; John Dunagan

95

An empirical evaluation of the fuzzy kernel perceptron.  

UK PubMed Central (United Kingdom)

J.-H. Chen and C.-S. Chen have recently proposed a nonlinear variant of Keller and Hunt's fuzzy perceptron algorithm, based on the now familiar "kernel trick." In this letter, we demonstrate experimentally that J.-H. Chen and C.-S. Chen's assertion that the fuzzy kernel perceptron (FKP) outperforms the support vector machine (SVM) cannot be sustained. A more thorough model comparison exercise, based on a much wider range of benchmark data sets, shows that the FKP algorithm is not competitive with the SVM.

Cawley GC

2007-05-01

96

Performance surfaces of a single-layer perceptron.  

Science.gov (United States)

A perceptron learning algorithm may be viewed as a steepest-descent method whereby an instantaneous performance function is iteratively minimized. An appropriate performance function for the most widely used perceptron algorithm is described and it is shown that the update term of the algorithm is the gradient of this function. An example is given of the corresponding performance surface based on Gaussian assumptions and it is shown that there is an infinity of stationary points. The performance surfaces of two related performance functions are examined. Computer simulations that demonstrate the convergence properties of the adaptive algorithms are given. PMID:18282846

Shynk, J J

1990-01-01

97

Performance surfaces of a single-layer perceptron.  

UK PubMed Central (United Kingdom)

A perceptron learning algorithm may be viewed as a steepest-descent method whereby an instantaneous performance function is iteratively minimized. An appropriate performance function for the most widely used perceptron algorithm is described and it is shown that the update term of the algorithm is the gradient of this function. An example is given of the corresponding performance surface based on Gaussian assumptions and it is shown that there is an infinity of stationary points. The performance surfaces of two related performance functions are examined. Computer simulations that demonstrate the convergence properties of the adaptive algorithms are given.

Shynk JJ

1990-01-01

98

Using the Perceptron Algorithm to Find Consistent Hypotheses  

UK PubMed Central (United Kingdom)

The perceptron learning algorithm yields quite naturally an algorithm for finding a linearly separable boolean function consistent with a sample of such a function. Using the idea of a specifying sample, we give a simple proof that this algorithm is not efficient, in general.

Martin Anthony; John Shawe-taylor

99

Estimativa do perfil da concentração de clorofila em águas naturais através de um perceptron de múltiplas camadas  

Scientific Electronic Library Online (English)

Full Text Available Abstract in portuguese Estimativa do perfil de concentração de clorofila, em águas naturais, a partir da radiação emergente na superfície de um corpo d'agua, com o uso de rede neural artificial do tipo Perceptron de Múltiplas Camadas. A concentração de clorofila está relacionada com os coeficientes de absorção e espalhamento via modelos bio-ópticos. O treinamento da rede é formulado como um problema de otimização, no qual a atualização das variáveis livres da rede (pesos, viés e parâmetros de cada função de ativação) é feita através do método quasi-Newton. Abstract in english In this work the average profile of chlorophyll concentration is estimated from the emitted radiation at the surface of natural waters. This is performed through the use an Artificial Neural Network of Multilayer Perceptron type to act as the inverse operator. Bio-optical models are used to correlate the chlorophyll concentration with the absorption and scattering coefficients. The network training is formulated as an optimization problem, in which the update of the free (more) variables of network (weights, viéses and each slope of the activation functions) is performed through the quasi-Newton method.

Dall Cortivo, F.; Chalhoub, E. S.; Campos Velho, H. F.

2012-12-01

100

The Role of Weight Shrinking in Large Margin Perceptron Learning  

CERN Multimedia

We introduce into the classical perceptron algorithm with margin a mechanism that shrinks the current weight vector as a first step of the update. If the shrinking factor is constant the resulting algorithm may be regarded as a margin-error-driven version of NORMA with constant learning rate. In this case we show that the allowed strength of shrinking depends on the value of the maximum margin. We also consider variable shrinking factors for which there is no such dependence. In both cases we obtain new generalizations of the perceptron with margin able to provably attain in a finite number of steps any desirable approximation of the maximal margin hyperplane. The new approximate maximum margin classifiers appear experimentally to be very competitive in 2-norm soft margin tasks involving linear kernels.

Panagiotakopoulos, Constantinos

2012-01-01

 
 
 
 
101

Optical perceptron learning for binary classification with spatial light rebroadcasters  

Science.gov (United States)

Binary classification of an object in a two-dimensional image is considered. A spatial light rebroadcaster is shown to be advantageous for learning in this case because it can store the weights and permit upward and downward adjustments. Two learning algorithms, based on the perceptron, are considered. A modification of the perceptron algorithm is developed so that only positive weights are needed. This is convenient because light intensity is positive only. The modified algorithm is shown to converge in a finite number of steps for positive linear separable classes. Optical experiments show the classification of four characters in two groups, in which alternative groupings are used to show robustness. In the second group of experiments the complements of the two-dimensional characters are used, and the convergence is equally fast. Adding the results from the original and complementary patterns provides a discrimination superior to that obtained using either on its own.

McAulay, Alastair D.; Wang, Junqing; Xu, Xin

1993-03-01

102

Optical perceptron learning for binary classification with spatial light rebroadcasters.  

UK PubMed Central (United Kingdom)

Binary classification of an object in a two-dimensional image is considered. A spatial light rebroadcaster is shown to be advantageous for learning in this case because it can store the weights and permit upward and downward adjustments. Two learning algorithms, based on the perceptron, are considered. A modification of the perceptron algorithm is developed so that only positive weights are needed. This is convenient because light intensity is positive only. The modified algorithm is shown to converge in a finite number of steps for positive linear separable classes. Optical experiments show the classification of four characters in two groups, in which alternative groupings are used to show robustness. In the second group of experiments the complements of the two-dimensional characters are used, and the convergence is equally fast. Adding the results from the original and complementary patterns provides a discrimination superior to that obtained using either on its own.

McAulay AD; Wang J; Xu X

1993-03-01

103

Higher-order probabilistic perceptrons as Bayesian inference engines  

International Nuclear Information System (INIS)

This letter makes explicit a structural connection between the Bayes optimal classifier operating on K binary input variables and corresponding two-layer perceptron having normalized output activities and couplings from input to output units of all orders up to K. Given a large and unbiased training set and an effective learning algorithm, such a neural network should be able to learn the statistics of the classification problem and match the a posteriori probabilities given by the Bayes optimal classifier. (author). 18 refs.

1994-01-01

104

A Novel Channel Equalizer Using Large Margin Algebraic Perceptron Network  

Directory of Open Access Journals (Sweden)

Full Text Available This paper proposes a novel control scheme for channel equalization for wireless communication system. The proposed scheme considers channel equalization as a classification problem. For efficient solution of the problem, this paper makes use of a neural network working on Algebraic Perceptron (AP) algorithm as a classifier. Also, this paper introduces a method of performance improvement by increasing margin of AP equalizers. Novelty of the proposed scheme is evidenced by its simulation results.

Priti R. Hathy; Sasmita K. Padhy; Siba P. Panigrahi; Prashant K. Patra

2010-01-01

105

Use of the 'Perceptron' algorithm to distinguish translational initiation sites in E. coli.  

UK PubMed Central (United Kingdom)

We have used a "Perceptron" algorithm to find a weighting function which distinguishes E. coli translational initiation sites from all other sites in a library of over 78,000 nucleotides of mRNA sequence. The "Perceptron" examined sequences as linear representations. The "Perceptron" is more successful at finding gene beginnings than our previous searches using "rules" (see previous paper). We note that the weighting function can find translational initiation sites within sequences that were not included in the training set.

Stormo GD; Schneider TD; Gold L; Ehrenfeucht A

1982-05-01

106

Identification of Non-Linear Structures using Recurrent Neural Networks  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Two different partially recurrent neural networks structured as Multi Layer Perceptrons (MLP) are investigated for time domain identification of a non-linear structure. , To be presented at the 13th Int. Modal Analysis Conference, Nashville, Tennessee, February 1995 PDF for print: 13 pp

Kirkegaard, Poul Henning; Nielsen, Søren R. K.; Hansen, H. I.

107

FORECASTING ON FOREX MARKET WITH RBF AND PERCEPTRON NEURAL NETWORKS  

Directory of Open Access Journals (Sweden)

Full Text Available This work deals with an alternative approach in financial modelling -artificial neural networks approach. The aim of this paper is to show that this type oftime series modelling is an excellent alternative to classical econometric modelling. Atfirst, neural networks using methods of supervised machine learning are discussed.After explaining theoretical basis of ANN, these models are then applied to specificexchange rate (AUD/USD). Finally, the comparison between statistical models andRBF and perceptron neural networks is made to illustrate the sense of using ANNmodels

LUKÁŠ FALÁT; ALEXANDRA KOTTILOVÁ

2012-01-01

108

Application of multilayer perceptron neural networks for predicting the permeability tensor components of thin ferrite films  

Science.gov (United States)

A novel characterization method using artificial neural networks is presented. This method allows one to determine the intrinsic permeability tensor of ferrite thin-films from S-parameters measurements. Neural networks, efficient to solve inverse problems, are used to compute the permeability tensor components ? and k. This optimization technique is used to find extremely complex functions between inputs and outputs and can be successfully applied on our magnetic thin-film characterization problem. Results of our networks are compared to a theoretical model. A great number of both simulated and measured tests have been performed on many magnetic thin-films. Neural network processing leads to a rapid and robust method for predicting the magnetic characterization of thin-films in microwave range.

Djerfaf, F.; Vincent, D.; Robert, S.; Merzouki, A.

2011-12-01

109

Speeding up a learning algorithm for multilayer perceptrons using the MAPS Environment  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Artificial neural networks, as non-linear adaptive elements, have been proposed for applications in adaptive control. Their ability to accurately approximate large classes of non-linear functions made them also a valuable tool for non-linear systems identification. However, in some cases, the parame...

Daniel, H.; Ruano, A. E.

110

The reactor safety study with help of artificial neuron networks (multilayer perceptrons)  

International Nuclear Information System (INIS)

[en] One deals with deposition of insulation large amounts on settling tank components that may result in malfunction of residual heat removal systems. Paper describes briefly simulation of pressure drops in confinement systems by means of an artificial neuron nets and compares the simulation data with the experiment ones

2008-01-01

111

24-hours ahead global irradiation forecasting using Multi-Layer Perceptron  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The grid integration of variable renewable energy sources implies that their effective production could be predicted, at different times ahead. In the case of solar plants, the driving factor is the global solar irradiation (sum of direct and diffuse solar radiation projected on a plane (Wh/m²)). Th...

Voyant, Cyril; Randimbivololona, Prisca; Nivet, Marie Laure; Paoli, Christophe; Muselli, Marc

112

Multilayer Networks  

CERN Multimedia

Most real and engineered systems include multiple subsystems and layers of connectivity, and it is important to take such features into account to try to obtain a complete understanding of these systems. It is thus necessary to generalize "traditional" network theory by developing (and validating) a framework and associated tools to study multilayer systems in a comprehensive fashion. The origins of such efforts occurred several decades ago, but now the study of multilayer networks has become one of the major directions in network science. In this paper, we discuss the history of multilayer networks (and related concepts) and then review the exploding body of work on such networks. To unify the disparate terminology in the large body of recent work, we discuss a general framework for multilayer networks, construct a dictionary of terminology to relate the numerous existing concepts to each other, and provide a thorough discussion that compares, contrasts, and translates between related notions such as multila...

Kivelä, Mikko; Barthelemy, Marc; Gleeson, James P; Moreno, Yamir; Porter, Mason A

2013-01-01

113

The Perceptron algorithm vs. Winnow: linear vs. logarithmic mistake bounds when few input variables are relevant  

UK PubMed Central (United Kingdom)

We give an adversary strategy that forces the Perceptron algorithm to make OmegaGamma kN ) mistakes in learning monotone disjunctions over N variables with at most k literals. In contrast, Littlestone's algorithm Winnow makes at most O(k log N ) mistakes for the same problem. Both algorithms use thresholded linear functions as their hypotheses. However, Winnow does multiplicative updates to its weight vector instead of the additive updates of the Perceptron algorithm. The Perceptron algorithm is an example of additive algorithms, which have the property that their weight vector is always a sum of a fixed initial weight vector and some linear combination of already seen instances. We show that an adversary can force any additive algorithm to make (N + k Gamma 1)=2 mistakes in learning a monotone disjunction of at most k literals. Simple experiments show that for k N , Winnow clearly outperforms the Perceptron algorithm also on nonadversarial random data.

J. Kivinen; M. K. Warmuth; Peter Auer

114

Holographic implementation of a learning machine based on a multicategory perceptron algorithm.  

UK PubMed Central (United Kingdom)

An optical learning machine that has multicategory classification capability is demonstrated. The system exactly implements the single-layer perceptron algorithm and is fully parallel and analog. Experimental results on the learning by examples obtained from the system are described.

Paek EG; Wullert Ii JR; Patel JS

1989-12-01

115

Ranking Algorithms for Named-Entity Extraction: Boosting and the Voted Perceptron  

UK PubMed Central (United Kingdom)

We describe algorithms that rerank the top N hypotheses from a maximum-entropy tagger, the application being named-entity recognition in a corpus of web data. The first approach uses a boosting algorithm for ranking problems. The second approach uses the voted perceptron algorithm. Both algorithms give comparable, significant improvements over the maximum-entropy baseline. The voted perceptron algorithm can be considerably more efficient to train, at some cost in computation on test examples.

Michael Collins; Florham Park

116

Statistical Mechanical Analysis of the Dynamics of Learning in Perceptrons  

CERN Multimedia

We describe the application of tools from statistical mechanics to analyse the dynamics of various classes of supervised learning rules in perceptrons. The character of this paper is mostly that of a cross between a biased non-encyclopedic review and lecture notes: we try to present a coherent and self-contained picture of the basics of this field, to explain the ideas and tricks, to show how the predictions of the theory compare with (simulation) experiments, and to bring together scattered results. Technical details are given explicitly in an appendix. In order to avoid distraction we concentrate the references in a final section. In addition this paper contains some new results: (i) explicit solutions of the macroscopic equations that describe the error evolution for on-line and batch learning rules, (ii) an analysis of the dynamics of arbitrary macroscopic observables (for complete and incomplete trainingsets), leading to a general Fokker-Planck equation, and (iii) the macroscopic laws describing batch le...

Mace, C W H

1997-01-01

117

Intelligent control of HVAC systems. Part II: perceptron performance analysis  

Directory of Open Access Journals (Sweden)

Full Text Available This is the second part of a paper on intelligent type control of Heating, Ventilating, and Air-Conditioning (HVAC) systems. The whole study proposes a unified approach in the design of intelligent control for such systems, to ensure high energy efficiency and air quality improving. In the first part of the study it is considered as benchmark system a single thermal space HVAC system, for which it is assigned a mathematical model of the controlled system and a mathematical model(algorithm) of intelligent control synthesis. The conception of the intelligent control is of switching type, between a simple neural network, a perceptron, which aims to decrease (optimize) a cost index,and a fuzzy logic component, having supervisory antisaturating role for neuro-control. Based on numerical simulations, this Part II focuses on the analysis of system operation in the presence only ofthe neural control component. Working of the entire neuro-fuzzy system will be reported in a third part of the study.

Ioan URSU; Ilinca NASTASE; Sorin CALUIANU; Andreea IFTENE; George TECUCEANU; Adrian TOADER

2013-01-01

118

Learning processes in multilayer threshold nets.  

UK PubMed Central (United Kingdom)

An algorithm of learning in multilayer threshold nets without feedbacks is proposed. The net is built of threshold elements with binary inputs. During a learning process each input vector chi is accompanied by a teacher's decision omega (omega epsilon(1,...,M)). The pairs (chi[n], omega[n]) appear in successive steps independently according to some unknown stationary distribution p(chi, omega). The problem of learning of a threshold net has been decomposed to a series of problems of learning of the threshold elements. The proposed learning algorithm of the threshold elements has a perceptron-like form. It was proven that a decision rule of the threshold net stabilizes after a finite number of steps. For definite classes (p(chi,omega))K of distributions p(chi, omega), an optimal decision rule stabilizes after a finite number of steps. These classes (p(chi, omega))K also contain distributions describing learning processes with perturbations.

Bobrowski L

1978-11-01

119

Statistical Mechanics of On-line Ensemble Teacher Learning through a Novel Perceptron Learning Rule  

Science.gov (United States)

In ensemble teacher learning, ensemble teachers have only uncertain information about the true teacher, and this information is given by an ensemble consisting of an infinite number of ensemble teachers whose variety is sufficiently rich. In this learning, a student learns from an ensemble teacher that is iteratively selected randomly from a pool of many ensemble teachers. An interesting point of ensemble teacher learning is the asymptotic behavior of the student to approach the true teacher by learning from ensemble teachers. The student performance is improved by using the Hebbian learning rule in the learning. However, the perceptron learning rule cannot improve the student performance. On the other hand, we proposed a perceptron learning rule with a margin. This learning rule is identical to the perceptron learning rule when the margin is zero and identical to the Hebbian learning rule when the margin is infinity. Thus, this rule connects the perceptron learning rule and the Hebbian learning rule continuously through the size of the margin. Using this rule, we study changes in the learning behavior from the perceptron learning rule to the Hebbian learning rule by considering several margin sizes. From the results, we show that by setting a margin of ?>0, the effect of an ensemble appears and becomes significant when a larger margin ? is used.

Hara, Kazuyuki; Miyoshi, Seiji

2012-06-01

120

The Perceptron algorithm vs. Winnow: linear vs. logarithmic mistake bounds when few input variables are relevant  

UK PubMed Central (United Kingdom)

We give an adversary strategy that forces thePerceptron algorithm to make (N Gamma k + 1)=2mistakes when learning k-literal disjunctionsover N variables. Experimentally we see thateven for simple random data, the number ofmistakes made by the Perceptron algorithmgrows almost linearly with N , even if the numberk of relevant variable remains a small constant.In contrast, Littlestone's algorithmWinnow makes at most O(k log N ) mistakesfor the same problem. Both algorithms uselinear threshold functions as their hypotheses.However, Winnow does multiplicative updatesto its weight vector instead of the additive updatesof the Perceptron algorithm.1 IntroductionThis paper addresses the familiar problem of predictingwith a linear threshold function. The instances are N -dimensional real vectors, and a threshold function isgiven by an N-dimensional real weight vector w anda real threshold `. The linear threshold function hasthe value 1 on an instance x if w Delta x `, a...

Jyrki Kivinen; Manfred K. Warmuth

 
 
 
 
121

The Perceptron algorithm vs. Winnow: linear vs. logarithmic mistake bounds when few input variables are relevant  

UK PubMed Central (United Kingdom)

We give an adversary strategy that forces the Perceptron algorithm to makeOmegaGamma kN) mistakes in learning monotone disjunctions over N variables with at mostk literals. In contrast, Littlestone's algorithm Winnow makes at most O(k log N)mistakes for the same problem. Both algorithms use thresholded linear functionsas their hypotheses. However, Winnow does multiplicative updates to its weightvector instead of the additive updates of the Perceptron algorithm. In general, wecall an algorithm additive if its weight vector is always a sum of a fixed initial weightvector and some linear combination of already seen instances. Thus, the Perceptronalgorithm is an example of an additive algorithm. We show that an adversary canforce any additive algorithm to make (N +k Gamma 1)=2 mistakes in learning a monotonedisjunction of at most k literals. Simple experiments show that for k ø N , Winnowclearly outperforms the Perceptron algorithm also on nonadversarial random data.Keywo...

J. Kivinen; M. K. Warmuth; P. Auer

122

Holographic implementation of a learning machine based on a multicategory perceptron algorithm.  

Science.gov (United States)

An optical learning machine that has multicategory classification capability is demonstrated. The system exactly implements the single-layer perceptron algorithm and is fully parallel and analog. Experimental results on the learning by examples obtained from the system are described. PMID:19759665

Paek, E G; Wullert Ii, J R; Patel, J S

1989-12-01

123

Ranking Algorithms for Named-Entity Extraction: Boosting and the Voted Perceptron  

UK PubMed Central (United Kingdom)

This paper describes algorithms whichrerank the top N hypotheses from amaximum-entropy tagger, the applicationbeing the recovery of named-entityboundaries in a corpus of web data. Thefirst approach uses a boosting algorithmfor ranking problems. The second approachuses the voted perceptron algorithm.

Michael Collins

124

Recurrent chylopericardium  

Science.gov (United States)

A 19-year-old male presented with recurrent episodes of pericardial effusion. On evaluation, he was diagnosed to have idiopathic chylous effusion. As there was persistent pericardial collection, chemical pericardiodesis was done. Following pericardiodesis, there was no recurrence of pericardial effusion. Chemical pericardiodesis may be an effective treatment option for recurrent, idiopathic chylopericardium.

Bhat, Prabhavathi; Ananthakrishna, Rajiv; Panneerselvam, Arunkumar; Yalagudri, Sachin Dhareppa; Rao, Prasanna Simha Mohan; Nanjappa, Manjunath C

2011-01-01

125

The Multilayer Firewall  

UK PubMed Central (United Kingdom)

We present a new security technology called theMultilayer Firewall. We argue that it is useful in somesituations for which other approaches, such ascryptographically protected communications, presentoperational or economic difficulties. In othercircumstances a Multilayer Firewall can complimentsuch security technology by providing additionalprotection against intruder attacks. We first present theoperational theory behind the Multilayer Firewall andthen describe a prototype that we designed andimplemented.

Dan Nessett; Polar Humenn

126

New Ranking Algorithms for Parsing and Tagging: Kernels over Discrete Structures, and the Voted Perceptron  

UK PubMed Central (United Kingdom)

This paper introduces new learning algorithms for natural language processing based onthe perceptron algorithm. We show how the algorithms can be efficiently applied toexponential sized representations of parse trees, such as the "all subtrees" (DOP)representation described by (Bod 98), or a representation tracking all sub-fragments of atagged sentence. We give experimental results showing significant improvements on twotasks: parsing Wall Street Journal text, and named-entity extraction from web data.

Michael Collinsy; Nigel Duffyz; Florham Park

127

New Ranking Algorithms for Parsing and Tagging: Kernels over Discrete Structures, and the Voted Perceptron  

UK PubMed Central (United Kingdom)

This paper introduces new learning algorithmsfor natural language processingbased on the perceptron algorithm. Weshow how the algorithms can be efficientlyapplied to exponential sized representationsof parse trees, such as the "all subtrees" (DOP) representation described by(Bod 1998), or a representation trackingall sub-fragments of a tagged sentence.We give experimental results showing significantimprovements on two tasks: parsingWall Street Journal text, and namedentityextraction from web data.1

Michael Collins; Florham Park; Nigel Duffy

128

Learning times of neural networks: Exact solution for a perceptron algorithm  

Science.gov (United States)

The performance of the optimal stability perceptron learning algorithm of Krauth and Mezard is studied for the learning of random unbiased patterns in neural networks. In the thermodynamic limit N, P-->?, ?=P/N finite, a replica approach is used to find the exact distribution for the number of time steps, which is required to stabilize a pattern. Remarkably for each neuron a finite fraction of the patterns do not contribute explicitly but are stabilized by other patterns.

Opper, M.

1988-10-01

129

Time-scale invariance as an emergent property in a perceptron with realistic, noisy neurons.  

UK PubMed Central (United Kingdom)

In most species, interval timing is time-scale invariant: errors in time estimation scale up linearly with the estimated duration. In mammals, time-scale invariance is ubiquitous over behavioral, lesion, and pharmacological manipulations. For example, dopaminergic drugs induce an immediate, whereas cholinergic drugs induce a gradual, scalar change in timing. Behavioral theories posit that time-scale invariance derives from particular computations, rules, or coding schemes. In contrast, we discuss a simple neural circuit, the perceptron, whose output neurons fire in a clockwise fashion based on the pattern of coincidental activation of its input neurons. We show numerically that time-scale invariance emerges spontaneously in a perceptron with realistic neurons, in the presence of noise. Under the assumption that dopaminergic drugs modulate the firing of input neurons, and that cholinergic drugs modulate the memory representation of the criterion time, we show that a perceptron with realistic neurons reproduces the pharmacological clock and memory patterns, and their time-scale invariance, in the presence of noise. These results suggest that rather than being a signature of higher order cognitive processes or specific computations related to timing, time-scale invariance may spontaneously emerge in a massively connected brain from the intrinsic noise of neurons and circuits, thus providing the simplest explanation for the ubiquity of scale invariance of interval timing.

Buhusi CV; Oprisan SA

2013-05-01

130

Gas Sensors Characterization and Multilayer Perceptron (MLP) Hardware Implementation for Gas Identification Using a Field Programmable Gate Array (FPGA)  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This paper develops a primitive gas recognition system for discriminating between industrial gas species. The system under investigation consists of an array of eight micro-hotplate-based SnO2 thin film gas sensors with different selectivity patterns. The output signals are processed through a signa...

Fayçal Benrekia; Mokhtar Attari; Mounir Bouhedda

131

Recurrent intussusception.  

UK PubMed Central (United Kingdom)

Recurrent intussusception is defined as an occurrence of intussusception of a bowel loop in a patient with a prior resolution of intussusception, either spontaneously or with an intervention. It is not rare to develop a subsequent episode after a successful reduction of intussusception. We report the cases of 2 children who presented to the emergency department with recurrent intussusception and review the pertinent literature.

Haber JJ; Waseem M

2013-06-01

132

Computer-assisted diagnosis of focal liver lesions on CT images evaluation of the Perceptron algorithm.  

UK PubMed Central (United Kingdom)

RATIONALE AND OBJECTIVE: The purpose of the study was to investigate a modified version of a so-called Perceptron algorithm in detecting focal liver lesions on CT scans. MATERIALS AND METHODS: The modified Perceptron algorithm is based on simulated annealing with a logarithmic cooling schedule and was implemented on a standard workstation. The algorithm was trained with 400 normal and 400 pathologic CT scans of the liver. An additional 100 normal and 100 pathologic scans were then used to test the detection of pathology by the algorithm. The total of 1000 scans used in the study were selected from the portal venous phase of upper abdominal CT examinations performed in patients with normal findings or hypovascularized liver lesions. The pathologic scans contained 1 to 4 focal liver lesions. For the preliminary version of the algorithm used in this study, it was necessary to define regions of interest that were converted to a matrix of 119 x 119. RESULTS: Training of the algorithm with 400 examples each of normal and abnormal findings took about 75 hours. Subsequently, the testing took several seconds for processing each scan. The diagnostic accuracy in discriminating scans with and without focal liver lesions achieved for the 200 test scans was approximately 99%. The error rate for pathologic and normal scans was comparable to results reported in the literature, which, however, were obtained for much smaller test sets. CONCLUSION: The modified Perceptron algorithm has an accuracy of close to 99% in detecting pathology on CT scans of the liver showing either normal findings or hypovascularized focal liver lesions.

Hein E; Albrecht A; Melzer D; Steinhöfel K; Rogalla P; Hamm B; Taupitz M

2005-09-01

133

Recurrent intussusception.  

Science.gov (United States)

Recurrent intussusception is defined as an occurrence of intussusception of a bowel loop in a patient with a prior resolution of intussusception, either spontaneously or with an intervention. It is not rare to develop a subsequent episode after a successful reduction of intussusception. We report the cases of 2 children who presented to the emergency department with recurrent intussusception and review the pertinent literature. PMID:23736072

Haber, Jordana J; Waseem, Muhammad

2013-06-01

134

Efficient Bayesian Inference for Learning in the Ising Linear Perceptron and Signal Detection in CDMA  

CERN Multimedia

Efficient new Bayesian inference technique is employed for studying critical properties of the Ising linear perceptron and for signal detection in Code Division Multiple Access (CDMA). The approach is based on a recently introduced message passing technique for densely connected systems. Here we study both critical and non-critical regimes. Results obtained in the non-critical regime give rise to a highly efficient signal detection algorithm in the context of CDMA; while in the critical regime one observes a first order transition line that ends in a continuous phase transition point. Finite size effects are also studied.

Neirotti, J P; Neirotti, Juan P.; Saad, David

2005-01-01

135

Discriminative Training Methods for Hidden Markov Models: Theory and Experiments with Perceptron Algorithms  

UK PubMed Central (United Kingdom)

We describe new algorithms for training tagging models, as an alternative to maximum-entropy models or conditional random fields (CRFs). The algorithms rely on Viterbi decoding of training examples, combined with simple additive updates. We describe theory justifying the algorithms through a modification of the proof of convergence of the perceptron algorithm for classification problems. We give experimental results on part-of-speech tagging and base noun phrase chunking, in both cases showing improvements over results for a maximum-entropy tagger.

Michael Collins

136

SoftDoubleMaxMinOver: perceptron-like training of support vector machines.  

UK PubMed Central (United Kingdom)

The well-known MinOver algorithm is a slight modification of the perceptron algorithm and provides the maximum-margin classifier without a bias in linearly separable two-class classification problems. DoubleMinOver as an extension of MinOver, which now includes a bias, is introduced. An O(t(-1)) convergence is shown, where t is the number of learning steps. The computational effort per step increases only linearly with the number of patterns. In its formulation with kernels, selected training patterns have to be stored. A drawback of MinOver and DoubleMinOver is that this set of patterns does not consist of support vectors only. DoubleMaxMinOver, as an extension of DoubleMinOver, overcomes this drawback by selectively forgetting all nonsupport vectors after a finite number of training steps. It is shown how this iterative procedure that is still very similar to the perceptron algorithm can be extended to classification with soft margins and be used for training least squares support vector machines (SVMs). On benchmarks, the SoftDoubleMaxMinOver algorithm achieves the same performance as standard SVM software.

Martinetz T; Labusch K; Schneegass D

2009-07-01

137

SoftDoubleMaxMinOver: perceptron-like training of support vector machines.  

Science.gov (United States)

The well-known MinOver algorithm is a slight modification of the perceptron algorithm and provides the maximum-margin classifier without a bias in linearly separable two-class classification problems. DoubleMinOver as an extension of MinOver, which now includes a bias, is introduced. An O(t(-1)) convergence is shown, where t is the number of learning steps. The computational effort per step increases only linearly with the number of patterns. In its formulation with kernels, selected training patterns have to be stored. A drawback of MinOver and DoubleMinOver is that this set of patterns does not consist of support vectors only. DoubleMaxMinOver, as an extension of DoubleMinOver, overcomes this drawback by selectively forgetting all nonsupport vectors after a finite number of training steps. It is shown how this iterative procedure that is still very similar to the perceptron algorithm can be extended to classification with soft margins and be used for training least squares support vector machines (SVMs). On benchmarks, the SoftDoubleMaxMinOver algorithm achieves the same performance as standard SVM software. PMID:19497817

Martinetz, Thomas; Labusch, Kai; Schneegass, Daniel

2009-06-02

138

Recurrent fevers.  

UK PubMed Central (United Kingdom)

An 11-year-old girl had four episodes of fever in a year, lasting 7-10 days and associated with headache and neck stiffness. She had a long history of recurrent urticaria, usually preceding the fevers. There was also a history of vague pains in her knees and in the small joints of her hands. Her serum C-reactive protein was moderately raised at 41?g/L (normal <8). Her rheumatologist felt the association of recurrent fevers that lasted 7 or more days with headaches, arthralgia and recurrent urticaria suggested one of the periodic fever syndromes. Genetic testing confirmed she had a gene mutation consistent with one of tumour necrosis factor receptor-associated periodic syndrome.

Isaacs D; Kesson A; Lester-Smith D; Chaitow J

2013-03-01

139

Efficient routing on multilayered communication networks  

Science.gov (United States)

We study the optimal routing on multilayered communication networks, which are composed of two layers of subnetworks. One is a wireless network, and the other is a wired network. We develop a simple recurrent algorithm to find an optimal routing on this kind of multilayered networks, where the single-channel transmission mode and the multichannel transmission mode used on the wireless subnetwork are considered, respectively. Compared with the performance of the shortest path algorithm, our algorithm can significantly enhance the transport capacity. We show that our methods proposed in this letter could take advantage of the coupling of the two layers to the most extent, so that the wireless subnetwork could sufficiently utilize the wired subnetwork for transportation.

Zhou, Jie; Yan, Gang; Lai, Choy-Heng

2013-04-01

140

Multilayer dielectric diffraction gratings  

Energy Technology Data Exchange (ETDEWEB)

The design and fabrication of dielectric grating structures with high diffraction efficiency used in reflection or transmission is described. By forming a multilayer structure of alternating index dielectric materials and placing a grating structure on top of the multilayer, a diffraction grating of adjustable efficiency, and variable optical bandwidth can be obtained. Diffraction efficiency into the first order in reflection varying between 1 and 98 percent has been achieved by controlling the design of the multilayer and the depth, shape, and material comprising the grooves of the grating structure. Methods for fabricating these gratings without the use of ion etching techniques are described.

Perry, Michael D. (Livermore, CA); Britten, Jerald A. (Oakley, CA); Nguyen, Hoang T. (Livermore, CA); Boyd, Robert (Livermore, CA); Shore, Bruce W. (Livermore, CA)

1999-01-01

 
 
 
 
141

Interfacial effects in multilayers  

Energy Technology Data Exchange (ETDEWEB)

There are many physical characterization approaches which evaluate a limited set of structural elements in multilayers: they study a single interface; they study a single layer of material; they study a very small sample of a multilayer. On a broader basis, the interference phenomena on which the performance of x-ray optic multilayers is based integrates over the full area/volume of the multilayer illuminated. In order to gain understanding of the impact of imperfections on multilayer performance it is necessary to develop an experimental approach that provides detailed information about the effects of interfaces in the multilayer obtained when the multilayer is being applied in a manner directly related to application. Additionally, it is also of interest to determine the breadth of application of any such experimental approach to the general study of interfaces in solids. The primary goal in this research was to develop an experimental methodology to quantitatively characterize both the physical and electronic characteristics of interfaces in multilayer structures. The approach was to fabricate multilayers from three elements so that one monolayer or less thick ''marker layers'' were selectively deposited on a given set interfaces in the multilayer. These ''marker layers'' could then interrogated by scattering and fluorescence techniques for their distribution, for their atomic arrangements relative to the thicker layers and for their electronic state at the interfaces as affected by the thicker layer materials. WC/C multilayers with one monolayer (2.33 {angstrom}) of tantalum at the WC on C and the C on WC interfaces were fabricated and studied. Ta was selected as the marker layer material as its L{sub 3} absorption edge is at 9879 eV, more than 300 eV less than the W L{sub 3} edge at 10200 eV. Reflectivities at 9850 eV, 9879 eV and 9950 eV were measured: Ta layers standing wave fluorescence on the multilayer Bragg peak at these energies and fluorescence EXAFS of the Ta layers were also obtained. These results are modeled and the implications of the results for x-ray optic structures and the study of buried interfaces in solids discussed.

Barbee, T W

1999-06-28

142

BaTiO3-based optical quadratic neural network implementing the perceptron algorithm  

Science.gov (United States)

An optical quadratic neural network (OQNN) utilizing four-wave mixing in barium titanate (BaTiO3) has been developed. This network implements a feedback loop using a CCD camera, a microcomputer, two monochrome liquid crystal televisions (LCTVs), and various optical elements. For training, the network employs the supervised quadratic perceptron algorithm to associate binary-valued input vectors with specified training vectors. Using a spatial multiplexing scheme for two bipolar neurons, the quadratic network was able to associate an input vector with various target vectors. In addition, the network successfully associated two input vectors with two corresponding target vectors in the same training session. Both analytical and experimental results are presented.

Huynh, Alex V.; Walkup, John F.; Krile, Thomas F.

1992-05-01

143

Applications of multilayer optics  

International Nuclear Information System (INIS)

[en] Recent development of multilayer mirror and its applications in extreme ultraviolet (EUV), soft X-ray ranges in China was reviewed in this paper. Three types of multilayer mirrors were developed with special performance for dense plasma diagnostics, EUV astronomical observation. Firstly, dual-periodic W/B4C multilayer mirror was designed for Kirkpatrick-Baez (K-B) microscopy working at TiK? line (4.75 keV), which is highly reflective both at hard X-ray (CuK? line at 8.05 keV) and soft X-ray (4.75 keV). Using this mirror, the K-B system can be aligned conveniently in air using hard X-ray instead of in vacuum. The second mirror is aperiodic Mg/SiC multilayer, also a bi-functional mirror with high reflectivity for He-II emission line (30.4 nm) but suppressing He-I emission line (58.4 nm) in astronomy observation, which will replace the traditional combination of periodic multilayer and the fragile film filter. This will be more safe in satellite launching. The third mirror is Mo/Si periodic multilayer, depositing on a parabolic substrate with diameter of 230 mm, which is designed for EUV telescope for imaging of solar corona by selecting Fe-XII emission (19.5 nm). The uniformity of lateral layer thickness distribution is within ±0.3% along the diameter of mirror, measured by X-ray reflectometry. The measured peak reflectivity is 42% at the wavelength of 19.5 nm. All these multilayer mirrors were prepared by using magnetron sputtering system in our group.

2010-11-11

144

EXAFS studied of multilayer Interfaces  

International Nuclear Information System (INIS)

Important for the understanding of multilayer materials is a determination of their structure. The extended x-ray absorption fine structure (EXAFS) technique can be useful, particularly for interfaces with a high degree of structural disorder. This paper reviews the application of EXAFS to multilayers, and describe the standing wave enhancement of the EXAFS from multilayer interfaces. Examples are given for W-C and Ni-Ti multilayers.

1989-01-01

145

Extreme ultraviolet multilayer reflectors  

Energy Technology Data Exchange (ETDEWEB)

We have investigated the design, fabrication, and reflectance measurements of a multilayer silver/silicon reflector for use at 58.4 nm. Our results indicate that reflectors in the extreme ultraviolet do not perform as well as predicted due to the presence of surface oxides and other surface contamination layers. In addition, we have found that the correct optical constants for silver have now been published. We find also that these multilayer coatings can be utilized as reflective polarizers in the EUV with an extinction ratio of 75:1 and a throughput of 28% for the s-polarized component of the beam.

Scott, M.L.; Arendt, P.N.; Cameron, B.J.; Newman, B.E.; Windt, D.; Cash, W.

1986-01-01

146

Metallic multilayers and superlattices  

Energy Technology Data Exchange (ETDEWEB)

An introduction to metal-metal multilayers and superlattices is presented, along with a brief review of some of the materials which have been made in our lab, and phenomena which have been observed so far. Results of a number of x-ray structural characterization techniques applied to these materials are described. These include Bragg THETA-2THETA x-ray diffraction, transmission and reflection Laue diffraction, and wide-film Debye-Scherrer diffraction. Emphasis is placed on recent results obtained in our laboratory with multilayers and superlattices produced by sputtering techniques.

Falco, C.M.

1985-01-01

147

Debugging of neural network based on 3-layer perceptron by the example of expert system in ophthalmology  

Directory of Open Access Journals (Sweden)

Full Text Available The algorithm of development of full set of tests for debugging of neural network expert systems based on threelayer perceptron is considered. The algo-rithm is based on rules extraction from neural network and using of the method of technical diagnostics PODEM. The use of algorithm for testing of expert sys-tem Glaukoma Complaint for prognosis of compliance of ophthalmologic patients is described.

Dolinina Olga Ni?kolaevna; Kuzmin Alexey Konstantinovich

2011-01-01

148

Multicategory nets of single-layer perceptrons: complexity and sample-size issues.  

UK PubMed Central (United Kingdom)

The standard cost function of multicategory single-layer perceptrons (SLPs) does not minimize the classification error rate. In order to reduce classification error, it is necessary to: 1) refuse the traditional cost function, 2) obtain near to optimal pairwise linear classifiers by specially organized SLP training and optimal stopping, and 3) fuse their decisions properly. To obtain better classification in unbalanced training set situations, we introduce the unbalance correcting term. It was found that fusion based on the Kulback-Leibler (K-L) distance and the Wu-Lin-Weng (WLW) method result in approximately the same performance in situations where sample sizes are relatively small. The explanation for this observation is by theoretically known verity that an excessive minimization of inexact criteria becomes harmful at times. Comprehensive comparative investigations of six real-world pattern recognition (PR) problems demonstrated that employment of SLP-based pairwise classifiers is comparable and as often as not outperforming the linear support vector (SV) classifiers in moderate dimensional situations. The colored noise injection used to design pseudovalidation sets proves to be a powerful tool for facilitating finite sample problems in moderate-dimensional PR tasks.

Raudys S; Kybartas R; Zavadskas EK

2010-05-01

149

Cu(100) multilayer relaxation  

International Nuclear Information System (INIS)

To investigate whether multilayer relaxation could be demonstrated to exist in a relatively simple metallic surface, existing LEED data for Cu(100) have been reanalyzed. The results from the new analysis clearly provide evidence for multilayer relaxation in Cu(100), and the first and second interlayer spacing are indicated to deviate (-1.10 +- 0.40)% and (+1.70 +- 0.60)%, respectively, from the bulk value. Evidence is also found to suggest that the third interlayer spacing is expanded by more than 1%. The quoted values for the deviations of the first and second interlayer spacings are mean values which resulted from analyses of data for each of 16 individual I-V profiles, while the error limits were obtained for a 95% confidence level using a student-t statistics test. The above values also were found to be consistent with results obtained when different multibeam ''R-factors'' were used to analyze averaged experimental I-V profiles

1982-01-01

150

Mobile Multilayer IPsec protocol  

Directory of Open Access Journals (Sweden)

Full Text Available A mobile user moves around and switches between wireless cells, subnets and domains, it needs to maintain the session continuity. At the same time security of signaling and transport media should not be compromised. A multi-layer security framework involving user authentication, packet based encryption and access control mechanism can provide the desired level of security to the mobile users. Supporting streaming traffic in a mobile wireless Internet is faced with several challenges due to continuous handoff experienced by a mobile user. These challenges include dynamic binding, location management, quality of service and end-to-end security for signaling and transport. Mobile users will use heterogeneous radio access networking technologies. Mobile multilayer IPsec protocol (MML IPSec) extends ML-IPSec to deal with mobility and make it suitable for wireless networks. MML-IPSec is integration of ML-IPSec and mobile IP.

T.Gayathri; S.Venkadajothi; S.Kalaivani; C.Divya; Dr.C.Suresh Gnana Dhas

2009-01-01

151

The Multidimensional Cube Recurrence  

CERN Document Server

We introduce a recurrence which we term the multidimensional cube recurrence, generalizing the octahedron recurrence studied by Propp, Fomin and Zelevinsky, Speyer, and Fock and Goncharov and the three-dimensional cube recurrence studied by Fomin and Zelevinsky, and Carroll and Speyer. The states of this recurrence are indexed by tilings of a polygon with rhombi, and the variables in the recurrence are indexed by vertices of these tilings. We travel from one state of the recurrence to another by performing elementary flips. We show that the values of the recurrence are independent of the order in which we perform the flips; this proof involves nontrivial combinatorial results about rhombus tilings which may be of independent interest. We then show that the multidimensional cube recurrence exhibits the Laurent phenomenon -- any variable is given by a Laurent polynomial in the other variables. We recognize a special case of the multidimensional cube recurrence as giving explicit equations for the isotropic Gras...

Henriques, Andre

2007-01-01

152

[Non-freeze epikeratoplasty in recurrent pterygium  

UK PubMed Central (United Kingdom)

We present five patients with recurrent pterygium. Prior to our surgical procedure the patients had had several surgical interventions as well as radiotherapy. Up to four-fifths of their corneal surface was covered by a multilayered pterygium including symblepharon scarring in the lower and upper lid, completely immobilizing the globe. The pterygium was removed, the conjunctival strains excised, and corneal abrasion was carried out with a rotating diamond tool. Finally, an optical non-freeze epikeratoplasty processed by the Non-freeze Barraquer-Krumreich-Swinger refractive set (BKS-1000) was sewn on the recipient cornea with a double running antitorque suture. In all patients, the epikeratoplasty donor cornea remained clear. In one patient there was a small pterygium recurrence, which was treated successfully with 5-fluorouracil.

Radda TM; Grasl M

1989-01-01

153

[Non-freeze epikeratoplasty in recurrent pterygium].  

Science.gov (United States)

We present five patients with recurrent pterygium. Prior to our surgical procedure the patients had had several surgical interventions as well as radiotherapy. Up to four-fifths of their corneal surface was covered by a multilayered pterygium including symblepharon scarring in the lower and upper lid, completely immobilizing the globe. The pterygium was removed, the conjunctival strains excised, and corneal abrasion was carried out with a rotating diamond tool. Finally, an optical non-freeze epikeratoplasty processed by the Non-freeze Barraquer-Krumreich-Swinger refractive set (BKS-1000) was sewn on the recipient cornea with a double running antitorque suture. In all patients, the epikeratoplasty donor cornea remained clear. In one patient there was a small pterygium recurrence, which was treated successfully with 5-fluorouracil. PMID:2625288

Radda, T M; Grasl, M

1989-01-01

154

Multilayer X-Rays mirrors  

Energy Technology Data Exchange (ETDEWEB)

The angular, dispersive, polarization and energy features of multilayer x-ray optics are considered within the framwork of unified theoretical approach. The ultimate optical parameters of multilayer structures are investigated, and the possibilities of their application to certain physical problems are discussed. Practical recommendations and techniques for fabrication x-ray interference mirrors are considered.

Kozhevnikov, I.V.; Vinogradov, A.V. [P.N. Lebedev Physical Institute, Moscow (Russian Federation)

1995-07-01

155

Magneto-optical multilayers  

Energy Technology Data Exchange (ETDEWEB)

Magneto-optical multilayers are of interest to the optical data storage community as a possible second-generation medium of the future. The important Co/Pt-superlattice system is introduced in this respect, and an extensive reference listing is provided to previous research. Magneto-optical modeling studies of Co/Pt are presented, and it is concluded that the interfacial Pt is magnetized and is magneto-optically active at the short wavelengths of interest ({approximately}4 eV) for applications. Magneto-optics in the ultrathin limit are discussed, and an additivity law is presented and verified experimentally utilizing data for epitaxial Fe/Ag(111) superlattices. Finally, the surface magnetic anisotropy that provides the vertical easy axes of magnetization in candidate superlattice systems is discussed and illustrated experimentally using ultrathin epitaxial films of Fe grown on a variety of substrates. It is concluded that magneto-optic multilayers will provide many stimulating basic and applied challenges in the years ahead.

Bader, S.D.

1992-02-01

156

Screening in multilayer graphene  

Science.gov (United States)

In this paper, we study the static polarization in ABC-stacked multilayer graphene. Since the density of states diverges for these systems if the number of layers exceeds three, screening effects are expected to be important. In the random phase approximation, screening can be included through the polarization. We derive an analytical integral expression for the polarization in both the full-band model and an effective two-band model. Numerical evaluation of these integrals is very time consuming in the full-band model. Hence, for ABC-stacked trilayer graphene, we use the two-band model to calculate the low momentum part of the polarization. The results for the two-band model are universal, i.e., independent of doping. The high momentum part is linear and is determined by calculating two points, such that we can determine the slope. For ABC stacked trilayer graphene, the slope is given by three times the monolayer value. We compare our results to previous ones in the literature and discuss the similarities and discrepancies. Our results can be used to include screening in ABC-stacked multilayer systems in a way that all the characteristics of the polarization function are included. The numerical results for the polarization of trilayer graphene are used to sketch the screened potential.

van Gelderen, Ralph; Olsen, Richard; Smith, C. Morais

2013-09-01

157

Magnetic metallic multilayers  

Energy Technology Data Exchange (ETDEWEB)

Utilizing self-consistent Hartree-Fock calculations, several aspects of multilayers and interfaces are explored: enhancement and reduction of the local magnetic moments, magnetic coupling at the interfaces, magnetic arrangements within each film and among non-neighboring films, global symmetry of the systems, frustration, orientation of the various moments with respect to an outside applied field, and magnetic-field induced transitions. Magnetoresistance of ferromagnetic-normal-metal multilayers is found by solving the Boltzmann equation. Results explain the giant negative magnetoresistance encountered in these systems when an initial antiparallel arrangement is changed into a parallel configuration by an external magnetic field. The calculation depends on (1) geometric parameters (thicknesses of layers), (2) intrinsic metal parameters (number of conduction electrons, magnetization, and effective masses in layers), (3) bulk sample properties (conductivity relaxation times), (4) interface scattering properties (diffuse scattering versus potential scattering at the interfaces, and (5) outer surface scattering properties (specular versus diffuse surface scattering). It is found that a large negative magnetoresistance requires considerable asymmetry in interface scattering for the two spin orientations. Features of the interfaces that may produce an asymmetrical spin-dependent scattering are studied: varying interfacial geometric random roughness with no lateral coherence, correlated (quasi-periodic) roughness, and varying chemical composition of the interfaces. The interplay between these aspects of the interfaces may enhance or suppress the magnetoresistance, depending on whether it increases or decreases the asymmetry in the spin-dependent scattering of the conduction electrons.

Hood, R.Q.

1994-04-01

158

Cu(100) multilayer relaxation  

Energy Technology Data Exchange (ETDEWEB)

To investigate whether multilayer relaxation could be demonstrated to exist in a relatively simple metallic surface, existing LEED data for Cu(100) have been reanalyzed. The results from the new analysis clearly provide evidence for multilayer relaxation in Cu(100), and the first and second interlayer spacing are indicated to deviate, respectively (-1.10 +- 0.40)% and (+1.70 +- 0.60)%, from the bulk value. Evidence is also found to suggest that the third interlayer spacing is expanded by more than 1%. The quoted values for the deviations of the first and second interlayer spacings are mean values which resulted from analyses of data for each of 16 individual I-V profiles, while the error limits were obtained for a 95% confidence level using a Student t statistics test. The above values were found also to be consistent with results obtained when different multi-beam R-factors were used to analyze averaged experimental I-V profiles.

Davis, H.L.; Noonan, J.R.

1981-01-01

159

Lipid multilayer gratings.  

Science.gov (United States)

The interaction of electromagnetic waves with matter can be controlled by structuring the matter on the scale of the wavelength of light, and various photonic components have been made by structuring materials using top-down or bottom-up approaches. Dip-pen nanolithography is a scanning-probe-based fabrication technique that can be used to deposit materials on surfaces with high resolution and, when carried out in parallel, with high throughput. Here, we show that lyotropic optical diffraction gratings--composed of biofunctional lipid multilayers with controllable heights between approximately 5 and 100 nm--can be fabricated by lipid dip-pen nanolithography. Multiple materials can be simultaneously written into arbitrary patterns on pre-structured surfaces to generate complex structures and devices, allowing nanostructures to be interfaced by combinations of top-down and bottom-up fabrication methods. We also show that fluid and biocompatible lipid multilayer gratings allow label-free and specific detection of lipid-protein interactions in solution. This biosensing capability takes advantage of the adhesion properties of the phospholipid superstructures and the changes in the size and shape of the grating elements that take place in response to analyte binding. PMID:20190751

Lenhert, Steven; Brinkmann, Falko; Laue, Thomas; Walheim, Stefan; Vannahme, Christoph; Klinkhammer, Soenke; Xu, Miao; Sekula, Sylwia; Mappes, Timo; Schimmel, Thomas; Fuchs, Harald

2010-02-28

160

Lipid multilayer gratings.  

UK PubMed Central (United Kingdom)

The interaction of electromagnetic waves with matter can be controlled by structuring the matter on the scale of the wavelength of light, and various photonic components have been made by structuring materials using top-down or bottom-up approaches. Dip-pen nanolithography is a scanning-probe-based fabrication technique that can be used to deposit materials on surfaces with high resolution and, when carried out in parallel, with high throughput. Here, we show that lyotropic optical diffraction gratings--composed of biofunctional lipid multilayers with controllable heights between approximately 5 and 100 nm--can be fabricated by lipid dip-pen nanolithography. Multiple materials can be simultaneously written into arbitrary patterns on pre-structured surfaces to generate complex structures and devices, allowing nanostructures to be interfaced by combinations of top-down and bottom-up fabrication methods. We also show that fluid and biocompatible lipid multilayer gratings allow label-free and specific detection of lipid-protein interactions in solution. This biosensing capability takes advantage of the adhesion properties of the phospholipid superstructures and the changes in the size and shape of the grating elements that take place in response to analyte binding.

Lenhert S; Brinkmann F; Laue T; Walheim S; Vannahme C; Klinkhammer S; Xu M; Sekula S; Mappes T; Schimmel T; Fuchs H

2010-04-01

 
 
 
 
161

Ultrahard Multilayer Coatings  

International Nuclear Information System (INIS)

We have developed a new multilayer a-tC material that is thick stress-free, adherent, low friction, and with hardness and stiffness near that of diamond. The new a-tC material is deposited by J pulsed-laser deposition (PLD) at room temperature, and fully stress-relieved by a short thermal anneal at 600 ampersand deg;C. A thick multilayer is built up by repeated deposition and annealing steps. We measured 88 GPa hardness, 1100 GPa Young's modulus, and 0.1 friction coefficient (under high load). Significantly, these results are all well within the range reported for crystalline diamond. In fact, this material, if considered separate from crystalline diamond, is the 2nd hardest material known to man. Stress-free a-tC also has important advantages over thin film diamond; namely, it is smooth, processed at lower temperature, and can be grown on a much broader range of substrates. This breakthrough will enable a host of applications that we are actively pursuing in MEMs, sensors, LIGA, etc

1999-01-01

162

Ultrahard Multilayer Coatings  

Energy Technology Data Exchange (ETDEWEB)

We have developed a new multilayer a-tC material that is thick stress-free, adherent, low friction, and with hardness and stiffness near that of diamond. The new a-tC material is deposited by J pulsed-laser deposition (PLD) at room temperature, and fully stress-relieved by a short thermal anneal at 600°C. A thick multilayer is built up by repeated deposition and annealing steps. We measured 88 GPa hardness, 1100 GPa Young's modulus, and 0.1 friction coefficient (under high load). Significantly, these results are all well within the range reported for crystalline diamond. In fact, this material, if considered separate from crystalline diamond, is the 2nd hardest material known to man. Stress-free a-tC also has important advantages over thin film diamond; namely, it is smooth, processed at lower temperature, and can be grown on a much broader range of substrates. This breakthrough will enable a host of applications that we are actively pursuing in MEMs, sensors, LIGA, etc.

Chrzan, D.C.; Dugger, M.; Follstaedt, D.M.; Friedman, Lawrence H.; Friedmann, T.A.; Knapp, J.A.; McCarty, K.F.; Medlin, D.L.; Mirkarimi, P.B.; Missert, N.; Newcomer, P.P.; Sullivan, J.P.; Tallant, D.R.

1999-05-01

163

Idiopathic, Recurrent Cholestasis.  

Science.gov (United States)

Idiopathic, recurrent cholestasis is characterized by episodes of obstructive jaundice often preceded by pruritus, steatorrhea, and purpuric rash. Between episodes of jaundice the liver histology is normal. We report a case of idiopathic, recurrent choles...

F. B. Ruymann A. Takeuchi H. W. Boyce

1969-01-01

164

Recurrent Breast Cancer  

Science.gov (United States)

... be reprinted for personal, noncommercial use only. Recurrent breast cancer By Mayo Clinic staff Original Article: http://www.mayoclinic.com/health/recurrent-breast-cancer/DS01078 Definition Symptoms Causes Risk factors Complications Preparing ...

165

SOM-MLP Multi-Layered Neural Network with False-Alarming Nodes for Large Scale Pattern Recognition  

Energy Technology Data Exchange (ETDEWEB)

In this paper, an SOM-MLP multi-layered neural network was studied for the large-scale pattern recognition problem such as the multilingual character recognition. The multi-layered neural network is made of the preclassification and the fine recognition modes. We constructed clusters for the preclassification mode using self-organizing map (SOM) learning and performed modifying steps for reducing the number of clusters. The clusters contain patterns that have the similar characteristics. We adopted the multi-layer perceptron(MLP) networks to the corresponding clusters for the fine recognition mode. And we proposed the use of false-alarming nodes in output layer of the MLP network, which could be constructed on error-prone negative examples quite similar to the patterns of the selected cluster but actually belonging to different nearby clusters through SOM`s topology-preserving mapping. The proposed system could be successfully adopted for recognizing the large number of printed Korean/Chinese characters database as well as IRIS database. (author). 14 refs., 13 figs., 2 tabs.

Kang, B.S.; Lim, K.T.; Chien, S.I. [Kyungpook National University, Taegu (Korea, Republic of)

1999-04-01

166

Recurrent zosteriform herpes simplex  

Directory of Open Access Journals (Sweden)

Full Text Available A 25-year-old man had recurrent zosteriform herpes simplex for past 6 years. The attacks were precipitated by prolonged exposure to sunlight. Pain was mild and lesions used to subside each time in about 7 days. Clinical features which help in differentiating recurrent herpes simplex from recurrent herpes zoster are summarized.

Inamadar Arun; Yatgiri R

1992-01-01

167

Recurrent zosteriform herpes simplex  

Digital Repository Infrastructure Vision for European Research (DRIVER)

A 25-year-old man had recurrent zosteriform herpes simplex for past 6 years. The attacks were precipitated by prolonged exposure to sunlight. Pain was mild and lesions used to subside each time in about 7 days. Clinical features which help in differentiating recurrent herpes simplex from recurrent h...

Inamadar Arun; Yatgiri R

168

Ultrasonic NDE of Multilayered Structures  

Energy Technology Data Exchange (ETDEWEB)

This project developed ultrasonic nondestructive evaluation techniques based on guided and bulk waves in multilayered structures using arrays. First, a guided wave technique was developed by preferentially exciting dominant modes with energy in the layer of interest via an ultrasonic array. Second, a bulk wave technique uses Fermat's principle of least time as well as wave-based properties to reconstruct array data and image the multilayered structure. The guided wave technique enables the inspection of inaccessible areas of a multilayered structure without disassembling it. Guided waves propagate using the multilayer as a waveguide into the inaccessible areas from an accessible position. Inspecting multi-layered structures with a guided wave relies on exciting modes with sufficient energy in the layer of interest. Multilayered structures are modeled to determine the possible modes and their distribution of energy across the thickness. Suitable modes were determined and excited by designing arrays with the proper element spacing and frequency. Bulk wave imaging algorithms were developed to overcome the difficulties of multiple reflections and refractions at interfaces. Reconstruction algorithms were developed to detect and localize flaws. A bent-ray algorithm incorporates Fermat's principle to correct time delays in the ultrasonic data that result from the difference in wave speeds in each layer and refractions at the interfaces. A planar wave-based algorithm was developed using the Green function for the multilayer structure to enhance focusing on reception for improved imaging.

Quarry, M J; Fisher, K A; Lehman, S K

2005-02-14

169

Multilayer diamond coated WC tools  

Energy Technology Data Exchange (ETDEWEB)

To increase adhesion of diamond coatings, a multilayer structure was developed. The multilayer diamond coating consisted of a first discontinuous diamond layer, an interposing layer, and a top continuous diamond layer. The diamond layer was grown on WC substrates by hot filament chemical vapor deposition and the interposing layer was grown by pulsed laser deposition. Machining tests were used to characterize adhesion properties of the multilayer diamond coatings on WC(Co) substrates. Results indicate that diamond coatings exhibit good adhesion on the WC tool substrates. The wear resistance of the WC tool is improved significantly by the diamond coatings.

Fan, W.D.; Jagannaham, K.; Narayan, J. [North Carolina State Univ., Raleigh, NC (United States)

1995-12-31

170

Sistema de análise de ativos através de redes neurais de múltiplas camadas. Asset analysis system using multilayer neural networks  

Directory of Open Access Journals (Sweden)

Full Text Available When investors decide to “adventure” through stock markets they search for a method to provide safety on making decision. In fact, there is no precise way to know which stocks will became a profitable investiment. Technical analysis is a discipline that support the investors on making decisions. Such a discipline uses a set of tools and statistical methods to forecast the market’s movement. Such a paper presents the develpment of a robotical Trade System, using a heuristic method. The system has a Neural Network multilayer perceptron, trained with an algorithm for back propagation error. Thus, approaching to the technical analysis without emotional aspects, using the Neural Network forecast on supporting the decisions of a investor on stock market. In analyzing the results of the neural network can be seen that the neural network got a result of 42.6% higher than the diagnostic of the technical analysis.Quando investidores decidem se “aventurar” pelo mercado de renda variável, como pelo mercado de ações, buscam um método de ter mais segurança na tomada de decisão. Na prática, não há como saber quais ativos tornar-se-ão um investimento lucrativo. No mercado acionário, a Análise Técnica procura auxiliar o investidor na tomada de decisão. Para isso, utiliza-se de ferramentas e de métodos estatísticos para tentar predizer os movimentos do mercado. Este artigo apresenta o desenvolvimento de um Trade System robótico, utilizando um método heurístico. O sistema conta com uma rede neural multilayer perceptron, treinada com o algoritmo de retro propagação de erro, aproximando-se da análise técnica sem o fator emoção. Ao avaliar os resultados da rede neural, pode ser visto que a mesma obteve um resultado de 42,6% maior do que o diagnóstico da análise técnica.

André Pacheco Miranda; Rodrigo Luiz Antoniazzi; Luis Felipe Dias Lopes; Marco Antonio Barbosa; Vânia Medianeira Flores Costa

2012-01-01

171

Imaging recurrent parosteal osteosarcoma  

International Nuclear Information System (INIS)

The aim of this study was to document the imaging features of recurrent parosteal osteosarcoma. The clinical and imaging records of 33 patients with a parosteal osteosarcoma referred to an orthopaedic oncology service over a 17-year period were retrospectively reviewed. The mode of identification of locally recurrent tumour was noted, together with the management and clinical outcome. Five patients developed a local recurrence of their parosteal osteosarcoma ranging from 6 months to 10 years after initial surgery. In 4 patients the recurrence was first suspected clinically due to the development of a mass. In the fifth patient recurrence was first detected on routine follow-up radiography. In 4 patients the recurrence could be identified on radiography as a mineralized mass. All the recurrences were readily identified on MR imaging, despite artefacts from prostheses. The recurrences were also evident in the 3 cases in which bone scintigraphy was performed. Local recurrence of parosteal osteosarcoma is adequately detected with a combination of clinical examination and conventional radiography. MR imaging is required to stage local recurrence or where radiography has failed to confirm clinically suspected recurrence. The routine use of MR imaging to follow-up patients is of doubtful value because of the frequently long time between initial surgery and relapse. (orig.)

2001-01-01

172

Imaging recurrent parosteal osteosarcoma  

Energy Technology Data Exchange (ETDEWEB)

The aim of this study was to document the imaging features of recurrent parosteal osteosarcoma. The clinical and imaging records of 33 patients with a parosteal osteosarcoma referred to an orthopaedic oncology service over a 17-year period were retrospectively reviewed. The mode of identification of locally recurrent tumour was noted, together with the management and clinical outcome. Five patients developed a local recurrence of their parosteal osteosarcoma ranging from 6 months to 10 years after initial surgery. In 4 patients the recurrence was first suspected clinically due to the development of a mass. In the fifth patient recurrence was first detected on routine follow-up radiography. In 4 patients the recurrence could be identified on radiography as a mineralized mass. All the recurrences were readily identified on MR imaging, despite artefacts from prostheses. The recurrences were also evident in the 3 cases in which bone scintigraphy was performed. Local recurrence of parosteal osteosarcoma is adequately detected with a combination of clinical examination and conventional radiography. MR imaging is required to stage local recurrence or where radiography has failed to confirm clinically suspected recurrence. The routine use of MR imaging to follow-up patients is of doubtful value because of the frequently long time between initial surgery and relapse. (orig.)

Johnson, K.; Davies, A.M.; Evans, N. [MRI Centre, Royal Orthopaedic Hospital, Birmingham (United Kingdom); Grimer, R.J. [Dept. of Orthopaedic Oncology, Royal Orthopaedic Hospital, Birmingham (United Kingdom)

2001-03-01

173

Multi-layers castings  

Directory of Open Access Journals (Sweden)

Full Text Available In paper is presented the possibility of making of multi-layers cast steel castings in result of connection of casting and welding coating technologies. First layer was composite surface layer on the basis of Fe-Cr-C alloy, which was put directly in founding process of cast carbon steel 200–450 with use of preparation of mould cavity method. Second layer were padding welds, which were put with use of TIG – Tungsten Inert Gas surfacing by welding technology with filler on Ni matrix, Ni and Co matrix with wolfram carbides WC and on the basis on Fe-Cr-C alloy, which has the same chemical composition with alloy, which was used for making of composite surface layer. Usability for industrial applications of surface layers of castings were estimated by criterion of hardness and abrasive wear resistance of type metal-mineral.

J. Szajnar; P. Wróbel; T. Wróbel

2010-01-01

174

Multilayer optical dielectric coating  

Energy Technology Data Exchange (ETDEWEB)

A highly damage resistant, multilayer, optical reflective coating includes alternating layers of doped and undoped dielectric material. The doping levels are low enough that there are no distinct interfaces between the doped and undoped layers so that the coating has properties nearly identical to the undoped material. The coating is fabricated at high temperature with plasma-assisted chemical vapor deposition techniques to eliminate defects, reduce energy-absorption sites, and maintain proper chemical stoichiometry. A number of differently-doped layer pairs, each layer having a thickness equal to one-quarter of a predetermined wavelength in the material are combined to form a narrowband reflective coating for a predetermined wavelength. Broadband reflectors are made by using a number of narrowband reflectors, each covering a portion of the broadband.

Emmett, John L. (Pleasanton, CA)

1990-01-01

175

Multilayer coatings on flexible substrates  

Energy Technology Data Exchange (ETDEWEB)

Thin-film optical and non-optical multilayer coatings are deposited onto flexible substrates using a vacuum web coater developed at Pacific Northwest Laboratory. The coater`s primary application is rapid prototyping of multilayer (1) polymer coatings, (2) polymer/metal coatings, (3) ceramic/metal coatings, and (4) hybrid polymer, ceramic, and metal coatings. The coater is fully automated and incorporates polymer evaporation and extrusion heads, high-rate magnetron sputtering cathodes, and e-beam evaporation sources. Polymer electrolytes are deposited by extrusion techniques. Flexible plastic, metal, and ceramic substrates can be coated using roll-to-roll or closed-loop configurations. Examples of multilayer optical coatings demonstrated to date are solar reflectors, heat mirrors, Fabry-Perot filters, and alpha particle sensors. Nonoptical coatings include multilayer magnetic metal/ceramic and lamellar composites.

Martin, P.M.; Affinito, J.D.; Gross, M.E.; Coronado, C.A.; Bennett, W.D.; Stewart, D.C.

1995-04-01

176

A comparative study of different feature sets for recognition of handwritten Arabic numerals using a Multi Layer Perceptron  

CERN Multimedia

The work presents a comparative assessment of seven different feature sets for recognition of handwritten Arabic numerals using a Multi Layer Perceptron (MLP) based classifier. The seven feature sets employed here consist of shadow features, octant centroids, longest runs, angular distances, effective spans, dynamic centers of gravity, and some of their combinations. On experimentation with a database of 3000 samples, the maximum recognition rate of 95.80% is observed with both of two separate combinations of features. One of these combinations consists of shadow and centriod features, i. e. 88 features in all, and the other shadow, centroid and longest run features, i. e. 124 features in all. Out of these two, the former combination having a smaller number of features is finally considered effective for applications related to Optical Character Recognition (OCR) of handwritten Arabic numerals. The work can also be extended to include OCR of handwritten characters of Arabic alphabet.

Das, Nibaran; Sarkar, Ram; Basu, Subhadip

2010-01-01

177

Branched coordination multilayers on gold.  

Science.gov (United States)

A C3-symmetric tridentate hexahydroxamate ligand molecule was specially synthesized and used for coordination self-assembly of branched multilayers on Au surfaces precoated with a self-assembled monolayer (SAM) of ligand anchors. Layer-by-layer (LbL) growth of multilayers via metal-organic coordination using Zr4+ ions proceeds with high regularity, adding one molecular layer in each step, as shown by ellipsometry, wettability, UV-vis spectroscopy, and atomic force microscopy (AFM). The branched multilayer films display improved stiffness, as well as a unique defect self-repair capability, attributed to cross-linking in the layers and lateral expansion over defects during multilayer growth. Transmetalation, i.e., exposure of Zr4+-based assemblies to Hf4+ ions, was used to evaluate the cross-linking. Conductive atomic force microscopy (AFM) was used to probe the electrical properties of the multilayers, revealing excellent dielectric behavior. The special properties of the branched layers were emphasized by comparison with analogous multilayers prepared similarly using linear (tetrahydroxamate) ligand molecules. The process of defect annihilation by bridging over defective areas, attributed to lateral expansion via the excess bishydroxamate groups, was demonstrated by introduction of artificial defects in the anchor monolayer, followed by assembly of two layers of either the linear or the branched molecule. Analysis of selective binding of Au nanoparticles (NPs) to unblocked defects emphasized the superior repair mechanism in the branched layers with respect to the linear ones. PMID:16351119

Wanunu, Meni; Vaskevich, Alexander; Cohen, Sidney R; Cohen, Hagai; Arad-Yellin, Rina; Shanzer, Abraham; Rubinstein, Israel

2005-12-21

178

Branched coordination multilayers on gold.  

UK PubMed Central (United Kingdom)

A C3-symmetric tridentate hexahydroxamate ligand molecule was specially synthesized and used for coordination self-assembly of branched multilayers on Au surfaces precoated with a self-assembled monolayer (SAM) of ligand anchors. Layer-by-layer (LbL) growth of multilayers via metal-organic coordination using Zr4+ ions proceeds with high regularity, adding one molecular layer in each step, as shown by ellipsometry, wettability, UV-vis spectroscopy, and atomic force microscopy (AFM). The branched multilayer films display improved stiffness, as well as a unique defect self-repair capability, attributed to cross-linking in the layers and lateral expansion over defects during multilayer growth. Transmetalation, i.e., exposure of Zr4+-based assemblies to Hf4+ ions, was used to evaluate the cross-linking. Conductive atomic force microscopy (AFM) was used to probe the electrical properties of the multilayers, revealing excellent dielectric behavior. The special properties of the branched layers were emphasized by comparison with analogous multilayers prepared similarly using linear (tetrahydroxamate) ligand molecules. The process of defect annihilation by bridging over defective areas, attributed to lateral expansion via the excess bishydroxamate groups, was demonstrated by introduction of artificial defects in the anchor monolayer, followed by assembly of two layers of either the linear or the branched molecule. Analysis of selective binding of Au nanoparticles (NPs) to unblocked defects emphasized the superior repair mechanism in the branched layers with respect to the linear ones.

Wanunu M; Vaskevich A; Cohen SR; Cohen H; Arad-Yellin R; Shanzer A; Rubinstein I

2005-12-01

179

Supratentorial recurrences in medulloblastoma  

Energy Technology Data Exchange (ETDEWEB)

Four children with medulloblastoma had massive supratentorial recurrences in the region of the cribriform plate after adequate craniospinal irradiation. The pathogenesis of these recurrences is probably related to underdosage to this region by shielding of the eyes. This hypothesis was corroborated by autopsy findings in two other patients in whom subfrontal implants were histologically different from recurrences elsewhere. Two possible solutions to avoid this problem in the future are suggested.

Jereb, B.; Sundaresan, N.; Horten, B.; Reid, A.; Galicich, J.H.

1981-02-15

180

Irreversible Multilayer Adsorption  

CERN Document Server

Random sequential adsorption (RSA) models have been studied due to their relevance to deposition processes on surfaces. The depositing particles are represented by hard-core extended objects; they are not allowed to overlap. Numerical Monte Carlo studies and analytical considerations are reported for 1D and 2D models of multilayer adsorption processes. Deposition without screening is investigated, in certain models the density may actually increase away from the substrate. Analytical studies of the late stage coverage behavior show the crossover from exponential time dependence for the lattice case to the power law behavior in the continuum deposition. 2D lattice and continuum simulations rule out some "exact" conjectures for the jamming coverage. For the deposition of dimers on a 1D lattice with diffusional relaxation we find that the limiting coverage (100%) is approached according to the ~1/t**0.5 power-law preceded, for fast diffusion, by the mean-field crossover regime with the intermediate ~1/t behavior...

Nielaba, P; Wang, J S

1993-01-01

 
 
 
 
181

Proximity effects of superconducting multilayer film  

Energy Technology Data Exchange (ETDEWEB)

The proximity effects of superconducting multilayer films composed of different metals are considered. The relationship between the critical temperature of a superconducting multilayer film with strong heterogeneity and its geometric structure is given.

Xueyu, C.; Daole, Y.

1984-07-01

182

Recurrent brain tumor  

International Nuclear Information System (INIS)

We have studied 12 patients, clinically suspected of recurrent brain tumor, using positron emission tomography (PET) with 18F-fluorodeoxyglucose (18FDG) and 11C-methionine (11C-MET). The main purpose of this study is the evaluation of the clinical capacity of PET for (1) early diagnosis of recurrent brain tumor, (2) malignant transformation of low grade glioma, and (3) differentiation between recurrent brain tumor and radiation necrosis. PET with 11C-MET clearly delineated the extension of recurrent tumor as focal high uptake of 11C-MET and was useful for early detection of recurrent tumor. Focal 18FDG-hypermetabolism was detected in 2 patients with malignant transformation of low grade glioma and revealed the usefulness for evaluation of malignant transformation. 18FDG-hypometabolism was observed in all patients with radiation necrosis, but was also found in one patient with recurrent malignant tumor. On the other hand, 11C-MET uptakes in radiation necrosis were similar to those in normal cortices in 2 patients with radiation necrosis. PET with 18FDG can be used to initially rule out recurrent tumor as hypermetabolism, and then recurrent tumor with 18FDG-hypometabolism might be differentiate from radiation necrosis by PET with 11C-MET. (author).

1990-01-01

183

Recurrent nerve locating system.  

UK PubMed Central (United Kingdom)

One recurring problem for otolaryngologists is the patient with vocal cord paralysis after thyroid surgery. We review the literature to assess the magnitude of this problem and to assess presently available techniques for sparing the recurrent laryngeal nerve. We present a new system for intraoperative recurrent laryngeal nerve location during thyroid surgery.

Rea JL; Davis WE; Templer JW

1979-01-01

184

Flood Recurrence Intervals  

Science.gov (United States)

This lab activity has students use stream discharge data obtained from the USGS Water Resources Division web site in order to calculate recurrence intervals for a local stream. Using the recurrence data generated, the students then make recommendations to the residents of a local town as to what they might do to reduce their loss from the effects of frequent flooding in their community.

Emerson, Norlene

185

Multilayer monochromators for neutron scattering  

International Nuclear Information System (INIS)

[en] In an earlier paper Schoenborn, Caspar, and Kammerer (J. Appl. Cryst. 7, 508-10(1974)) reported the fabrication of thin film monochromators for neutrons. They showed that a multilayer consisting of alternating films of two materials acts as a good monochromator with large and adjustable periodicity and wide bandwidth. The diffraction properties of these multilayers have been studied with the objective of using them as monochromators, filters and polarizers for neutrons. A theoretical understanding of these multilayers has been developed by using the kinematical and dynamical approaches. In order to compare these expressions with the observed properties, the effects of beam divergence and wavelength distribution for the spectrometer have been determined. The influence of some aperiodicity on the diffraction data has also been studied within the framework of kinematical theory. (auth)

1975-06-02

186

Digitally Encoded Exchange Biased Multilayers  

Science.gov (United States)

There is a high interest in magnetic multilayers for applications in biotechnology. Exchange biased systems are promising candidates for substituting magnetic beads in more complex applications that require each tag to carry digitally encoded information. We have studied the coercivity and exchange bias of Co/PdMn and CoFe/PdMn samples deposited by dc magnetron sputtering as a function of the materials thickness. We also have fabricated a multilayer comprised of four Co/PdMn bilayers that can be encoded in 16 different states, which are stable at zero applied field, thereby enabling the magnetic tag to store 4 bits of information.

Barbagallo, M.; van Belle, F.; Ionescu, A.; Bland, J. A. C.

2008-06-01

187

Imaging of recurrent prostate cancer.  

UK PubMed Central (United Kingdom)

Approximately 30% of patients who underwent radical prostatectomy or radiation therapy will develop biochemical recurrent disease. Biochemical recurrent disease is defined as an increase in the serum value of prostate-specific antigen (PSA) after reaching the nadir. Prostate recurrence can present as PSA-only relapse, local recurrent disease, distant metastases, or a combination of local and distant recurrence. In this review, the role of magnetic resonance imaging in the work-up of recurrent prostate cancer is discussed.

Fütterer JJ

2012-11-01

188

Treatment of recurrent craniopharyngiomas.  

UK PubMed Central (United Kingdom)

One of the most common complications of craniopharyngioma treatment is recurrence. The outcomes of treatment for recurrent tumors with different modalities were evaluated. Of the 61 patients treated initially, 24 had recurrence during follow-up period (1-29 years, mean 11 years). Twenty-two patients underwent a total of 35 additional operations for recurrence. With reoperation, total surgical removal was achieved for four occasions (Group a), subtotal resection was achieved with 31 surgical procedures. Nineteen procedures (Group b) were done without radiotherapy and seven were followed by radiotherapy (Group c). Seven patients were treated with radiosurgery (Group d) with or without surgical resection. The surgical mortality rate for Group a was 50% which was higher than for initial operation, while for Group b 10.5% and none for Groups c and d. Good functional status was maintained at follow-up in 50% of survived patients for Group a, 14% for Group b, 57% for Group c and 86% for Group d. The 5-year recurrence free survival rate was 50% for Group a, 16% for Group b, 80% for Group c, and 83.3% for Group d. The rate of recurrence free survival for Group b was significantly lower than Group c (P = 0.004) and Group d (P = 0.001). The recurrence free survival rates were higher for Groups c and d than for Group b. The mortality and morbidity higher in the Group a. Radiotherapy and radiosurgery are useful adjuncts for the treatment of recurrence, resulting in a high recurrent-free survival rate with better functional outcome.

Barua KK; Ehara K; Kohmura E; Tamaki N

2003-01-01

189

RECURRENT RECTAL CANCER  

Directory of Open Access Journals (Sweden)

Full Text Available The work has as scope to analyze the recurrence of the neoplazic disease after operated rectal cancer, the study including a lot of 246 patients operated between 1995 and 2005. 129 abdominoperineal resections, 88 anterior resections, 29 Hartmann operations were performed. In the series herein, 61 patients presented recurrences, out of which 35 local recurrences, 19 at distance and 7 mixed. The ratio of the local recurrence was of: 13.20% for the lot of patients with abdominoperineal resection, 14.80% for the ones with anterior rectal resections and 17.25% at the patients with Hartmann operations. The evolution of the recurrences after years does not emphasize a statistic discrimination by this criterion (Cramer indicator, V=0.643, p-value=0.323 in the case of abdominoperineal resections, Cramer indicator, V=0.573, p-value=0.381 for anterior resections and Cramer indicator, V=0.837, p-value=0.342 for Hartmann operations). It is to be noticed that if one is to monitor the patients with rectal resections in the period between 2000-2005, one can observe a much lower local recurrence ratio – 4.84% (only 3 local recurrences out of 62 cases). The ratio decrease can be explained by the fact that total mesorectal excision was constantly performed. The usage of the preoperative radiotherapy determines major decrease of the recurrence ratio (10.80%), comparable against adjuvant treatment. As a conclusion, the importance of complex, sequencial treatment is emphasized (preoperative radiotherapy – rectal resection through abdomen-perineum/abdomen with total mesorectal excision) for decreasing the recurrence of the disease both local and at distance.

C. Ple?ca; C. Dragomir; Silvia Tighiliu

2007-01-01

190

Ultrathin multilayer capsules in drug delivery  

Directory of Open Access Journals (Sweden)

Full Text Available Ultra thin multilayer capsules are attractive and stable systems capable of delivering the bioactives. Ultra thin multilayer capsules consist of polyelectrolytic materials that are formed in the presence of a template. This is achieved through layer-by-layer adsorption of oppositely charged macromolecules on to colloidal particles. Upon extraction, the resulting cavities retain affinity for the bioactives. This review considers the fabrication, of ultra thin multilayer capsules, physiochemical properties and role of ultra thin multilayer capsules within a pharmaceutical remit. Ultrathin multilayer capsules have potential for creating satisfactory drug dosage forms.

Jain Arti; Kumar P; Jain N

2007-01-01

191

Image quality of figured multilayered optics  

Energy Technology Data Exchange (ETDEWEB)

The reflectivity and resolution of a multilayer structure is strongly affected by the roughness at the interfaces between two successive layers and by the amount that the constituent materials will diffuse into one another at the interfaces. Performance is also affected by the variations in individual layer thicknesses and by inhomogeneities in the materials. These deviations from the ideal multilayer will also affect the quality of the image from a figured multilayer optical element. The theory used to model the effects of non-ideal multilayers on the image quality of figured optics will be discussed. The relationship between image quality and multilayer structure quality will be illustrated with several examples.

Peterson, B.G.; Knight, L.V.; Pew, H.K.

1985-01-01

192

Photochemical disruption of polyelectrolyte multilayers.  

UK PubMed Central (United Kingdom)

Photoreactive polyelectrolyte multilayers (PEMs) that dissolve upon UV irradiation are described. Light-induced switching of the formal charge of a photoreactive polycation resulted in repulsive interlayer electrostatic forces, and caused the dissolution of PEM films. Combining both photoreactive and inert polycations in the same film yielded additional control over the light-induced change in film thickness.

Koylu D; Thapa M; Gumbley P; Thomas SW 3rd

2012-03-01

193

Multilayer Controller for Outdoor Vehicle  

DEFF Research Database (Denmark)

A full software and hardware solution has been designed, implemented and tested for control of a small agricultural automatic tractor. The objective was to realise a user-friendly, multi-layer controller architecture for an outdoor platform. The collaborative research work was done as a part of a research project within the field of automated agriculture and precision farming.

Reske-Nielsen, Anders; Mejnertsen, AsbjØrn

2006-01-01

194

Recurrence in generic staircases  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The straight-line flow on almost every staircase and on almost every square tiled staircase is recurrent. For almost every square tiled staircase the set of periodic orbits is dense in the phase space.

Troubetzkoy, Serge

195

Recurrent congenital chylothorax.  

UK PubMed Central (United Kingdom)

Congenital chylothorax is an uncommon but well-described condition. Recurrent congenital chylothorax is extremely rare. Yancy and Spock (1967) reviewed 31 reported cases of spontaneous chylothorax which occurred in the first 2 months of life and noted that male infants were affected twice as commonly as females. Two other cases of recurrent congenital chylothorax in male offspring (Defoort and Thiery, 1978; Reece et al., 1987) led to the suggestion of possible X-linked recessive inheritance. We describe a case of recurrent congenital chylothorax in which two consecutive female infants in a sibship were affected. The underlying cause of this disorder remains unknown. Inheritance as an X-linked recessive is not possible and this case is suggestive of autosomal recessive inheritance. The case also serves to emphasize the need for caution in counselling for recurrence risks when the underlying aetiology of the disorder is unknown.

King PA; Ghosh A; Tang MH; Lam SK

1991-10-01

196

Recurrent congenital chylothorax.  

Science.gov (United States)

Congenital chylothorax is an uncommon but well-described condition. Recurrent congenital chylothorax is extremely rare. Yancy and Spock (1967) reviewed 31 reported cases of spontaneous chylothorax which occurred in the first 2 months of life and noted that male infants were affected twice as commonly as females. Two other cases of recurrent congenital chylothorax in male offspring (Defoort and Thiery, 1978; Reece et al., 1987) led to the suggestion of possible X-linked recessive inheritance. We describe a case of recurrent congenital chylothorax in which two consecutive female infants in a sibship were affected. The underlying cause of this disorder remains unknown. Inheritance as an X-linked recessive is not possible and this case is suggestive of autosomal recessive inheritance. The case also serves to emphasize the need for caution in counselling for recurrence risks when the underlying aetiology of the disorder is unknown. PMID:1800993

King, P A; Ghosh, A; Tang, M H; Lam, S K

1991-10-01

197

Recurrent desmoplastic fibroma.  

UK PubMed Central (United Kingdom)

Two cases of recurrent desmoplastic fibroma are reported and the relevant literature reviewed. In both cases the original lesion was incompletely removed more than 10 years previously and the slow but aggressive spread of the recurrences is documented. Desmoplastic fibromas are locally invasive tumors and primary surgical excision should be accomplished together with a margin of normal tissue. The second case also presented with an associated amputation neuroma and this topic is briefly discussed.

Summers L; Matz LR

1976-04-01

198

Recurrent desmoplastic fibroma.  

Science.gov (United States)

Two cases of recurrent desmoplastic fibroma are reported and the relevant literature reviewed. In both cases the original lesion was incompletely removed more than 10 years previously and the slow but aggressive spread of the recurrences is documented. Desmoplastic fibromas are locally invasive tumors and primary surgical excision should be accomplished together with a margin of normal tissue. The second case also presented with an associated amputation neuroma and this topic is briefly discussed. PMID:818038

Summers, L; Matz, L R

1976-04-01

199

[Recurrent pyogenic granuloma].  

UK PubMed Central (United Kingdom)

The appearance of multiple satellite lesions is a rare complication of the treatment of a primary pyogenic granuloma lesion. We report 5 cases of recurrent pyogenic granuloma in patients aged between 4 and 31 years. The lesions resolved spontaneously after 1 to 9 months. Although the diagnosis and treatment of recurrent pyogenic granuloma can be problematic, this condition is benign and frequently self-limiting.

Pitarch G; Pérez-Ferriols A; Millán F

2012-07-01

200

[Recurrent pyogenic granuloma].  

Science.gov (United States)

The appearance of multiple satellite lesions is a rare complication of the treatment of a primary pyogenic granuloma lesion. We report 5 cases of recurrent pyogenic granuloma in patients aged between 4 and 31 years. The lesions resolved spontaneously after 1 to 9 months. Although the diagnosis and treatment of recurrent pyogenic granuloma can be problematic, this condition is benign and frequently self-limiting. PMID:21872831

Pitarch, G; Pérez-Ferriols, A; Millán, F

2011-08-27

 
 
 
 
201

[Recurrent infective endocarditis  

UK PubMed Central (United Kingdom)

Between August, 1974 and May, 1987, 486 patients were treated for infective endocarditis. In 16 of these patients (12 men, 4 women, mean age 44.3 +/- 18.0 years at the time of the first episode) the endocarditis recurred: once in 14 patients, twice in 2 patients. The time elapsed between recovery from the first episode and onset of the recurrence varied from 6 to 159 months (mean 54.3 +/- 35.1 months). Among the 18 recurrences, 10 affected native valves (mitral 6, aortic 4) and 8 aortic prostheses. In all but one case the organism isolated during the recurrence (Streptococcus in 14 cases, Staphylococcus in 3 cases, Rickettsia in 1 case) was different from the organism responsible for the previous infection. The 16 patients were followed up for periods of 28 to 203 months (mean 107.0 +/- 58.0 months), counting from the onset of the first episode. Ten patients were treated medically during the second episode: 4 died and 2 had a second recurrence, lethal in one of them (time elapsed between the onset of the first episode and the date of death: 32 to 149 months). Six patients were operated upon (valve replacement in 5 cases, closure of a left aorto-ventricular fistula in 1 case) without deaths. Nine of the 11 survivors are now asymptomatic. The actuarial survival rate in recurrent endocarditis (75 p. 100, 10 years after the onset of the first episode) is not different from that observed in non-recurrent endocarditis.

Delahaye JP; Beuchot T; Delahaye F; Durand de Gevigney G; Etienne J; Malquarti V; Finet G

1989-04-01

202

Recurrent intussusception in infants.  

UK PubMed Central (United Kingdom)

AIM: Clinical features to identify infants at increased risk of recurrence after a primary episode of intussusception (IS) are poorly defined. METHODS: Prospective study of the clinical presentation, treatment and outcome in infants <2 years presenting with acute IS to the National Hospital of Pediatrics, Hanoi, over a 14-month period (1 November 2002 to 31 December 2003). A retrospective review of medical records was performed to verify complete patient ascertainment. RESULTS: Five hundred ninety-eight children were recruited, including 513 (86%) with a primary episode only and 53 (9%) with ?1 recurrent episodes. Another 32 (5%) infants presented with recurrent IS, but the primary episode of IS occurred outside the study period. Estimated recurrence risk at 6 months following a primary episode was 14%. A pathological lead point was rare in primary (n= 1) and recurrent IS (n= 1). Most infants were successfully treated with enema reduction. CONCLUSIONS: This study describes the natural history of recurrent IS in infants and may assist in interpreting data from post-marketing surveillance following introduction of rotavirus vaccines.

Justice FA; Nguyen LT; Tran SN; Kirkwood CD; Thi NT; Carlin JB; Bines JE

2011-11-01

203

Nonlinear blind equalization schemes using complex-valued multilayer feedforward neural networks.  

Science.gov (United States)

Among the useful blind equalization algorithms, stochastic-gradient iterative equalization schemes are based on minimizing a nonconvex and nonlinear cost function. However, as they use a linear FIR filter with a convex decision region, their residual estimation error is high. In this paper, four nonlinear blind equalization schemes that employ a complex-valued multilayer perceptron instead of the linear filter are proposed and their learning algorithms are derived. After the important properties that a suitable complex-valued activation function must possess are discussed, a new complex-valued activation function is developed for the proposed schemes to deal with QAM signals of any constellation sizes. It has been further proven that by the nonlinear transformation of the proposed function, the correlation coefficient between the real and imaginary parts of input data decreases when they are jointly Gaussian random variables. Last, the effectiveness of the proposed schemes is verified in terms of initial convergence speed and MSE in the steady state. In particular, even without carrier phase tracking procedure, the proposed schemes correct an arbitrary phase rotation caused by channel distortion. PMID:18255822

You, C; Hong, D

1998-01-01

204

Nonlinear blind equalization schemes using complex-valued multilayer feedforward neural networks.  

UK PubMed Central (United Kingdom)

Among the useful blind equalization algorithms, stochastic-gradient iterative equalization schemes are based on minimizing a nonconvex and nonlinear cost function. However, as they use a linear FIR filter with a convex decision region, their residual estimation error is high. In this paper, four nonlinear blind equalization schemes that employ a complex-valued multilayer perceptron instead of the linear filter are proposed and their learning algorithms are derived. After the important properties that a suitable complex-valued activation function must possess are discussed, a new complex-valued activation function is developed for the proposed schemes to deal with QAM signals of any constellation sizes. It has been further proven that by the nonlinear transformation of the proposed function, the correlation coefficient between the real and imaginary parts of input data decreases when they are jointly Gaussian random variables. Last, the effectiveness of the proposed schemes is verified in terms of initial convergence speed and MSE in the steady state. In particular, even without carrier phase tracking procedure, the proposed schemes correct an arbitrary phase rotation caused by channel distortion.

You C; Hong D

1998-01-01

205

Hyperhomocysteinemia in Recurrent Miscarriage  

International Nuclear Information System (INIS)

Objective: An elevated total plasma homocysteine level has been suggested as a possible risk factor in women suffering from recurrent pregnancy loss. The current study was undertaken to assess the association between homocysteine, folate, cobalamin (vitamin B12) and the risk of recurrent pregnancy loss. Design: Case . control study Materials and Methods: The study included 57 non-pregnant Egyptian women. They were classified according to their obstetric history into 2 groups: 32 cases with at least two consecutive miscarriages (Study group), and 25 cases with normal obstetric history (Control group). All cases were tested for plasma total homocysteine, serum folate and cobalamin (vitamin B12). Results: The fasting total homocysteine was significantly higher in the study group as compared to the control group. While the median concentrations for the vitamins studied were significantly lower in women of the study group as compared to the controls. Elevated homocysteine and reduced vitamin B12 can be considered risk factors for recurrent miscarriage with odds ratio (OR) and 95% confidence intervals (95% CI) of 1.839 (1.286, 2.63) and 1.993 (1.346, 2.951) respectively in the group of recurrent miscarriages. The OR (95% CI) in the study population for low serum folate concentrations was 1.23 (0.776, 2.256). Conclusion: Elevated homocysteine and reduced serum vitamin B12 are risk factors for recurrent miscarriage. Low serum folate did not seem a risk factor for recurrent miscarriage. Testing for homocysteine levels in women suffering from unexplained recurrent miscarriage and pre-conceptional supplementation with vitamin B12 might be beneficial to improve pregnancy outcome

2008-01-01

206

Anomalous magnetoresistance in Fibonacci multilayers.  

Energy Technology Data Exchange (ETDEWEB)

We theoretically investigated magnetoresistance curves in quasiperiodic magnetic multilayers for two different growth directions, namely, [110] and [100]. We considered identical ferromagnetic layers separated by nonmagnetic layers with two different thicknesses chosen based on the Fibonacci sequence. Using parameters for Fe/Cr multilayers, four terms were included in our description of the magnetic energy: Zeeman, cubic anisotropy, bilinear coupling, and biquadratic coupling. The minimum energy was determined by the gradient method and the equilibrium magnetization directions found were used to calculate magnetoresistance curves. By choosing spacers with a thickness such that biquadratic coupling is stronger than bilinear coupling, unusual behaviors for the magnetoresistance were observed: (i) for the [110] case, there is a different behavior for structures based on even and odd Fibonacci generations, and, more interesting, (ii) for the [100] case, we found magnetic field ranges for which the magnetoresistance increases with magnetic field.

Machado, L. D.; Bezerra, C. G.; Correa, M. A.; Chesman, C.; Pearson, J. E.; Hoffmann, A. (Materials Science Division); (Universidade Federal do Rio Grande do Norte)

2012-01-01

207

Anomalous magnetoresistance in Fibonacci multilayers  

Science.gov (United States)

We theoretically investigated magnetoresistance curves in quasiperiodic magnetic multilayers for two different growth directions, namely, [110] and [100]. We considered identical ferromagnetic layers separated by nonmagnetic layers with two different thicknesses chosen based on the Fibonacci sequence. Using parameters for Fe/Cr multilayers, four terms were included in our description of the magnetic energy: Zeeman, cubic anisotropy, bilinear coupling, and biquadratic coupling. The minimum energy was determined by the gradient method and the equilibrium magnetization directions found were used to calculate magnetoresistance curves. By choosing spacers with a thickness such that biquadratic coupling is stronger than bilinear coupling, unusual behaviors for the magnetoresistance were observed: (i) for the [110] case, there is a different behavior for structures based on even and odd Fibonacci generations, and, more interesting, (ii) for the [100] case, we found magnetic field ranges for which the magnetoresistance increases with magnetic field.

Machado, L. D.; Bezerra, C. G.; Correa, M. A.; Chesman, C.; Pearson, J. E.; Hoffmann, A.

2012-06-01

208

MULTI-LAYER MEDICAL BALLOONS  

UK PubMed Central (United Kingdom)

The invention relates to multi-layer medical balloons. In one aspect, a medical device includes an inflatable balloon. The inflatable balloon includ es a first layer including a material having a first modulus of elasticity, and a second layer adjacent the first layer, the second layer including a material having a second modulus of elasticity that differs from the first modulus of elasticity by at least about 2,000 psi. A cutting element is carried by the balloon.

WU SHOW-MEAN; LAREAU RAYMOND; GOEKEN KARA; CHEN FUH-SHENG

209

Multi-layer medical balloons  

UK PubMed Central (United Kingdom)

The invention relates to multi-layer medical balloons. In one aspect, a medical device includes an inflatable balloon. The inflatable balloon includes a first layer including a material having a first modulus of elasticity, and a second layer adjacent the first layer, the second layer including a material having a second modulus of elasticity that differs from the first modulus of elasticity by at least about 2,000 psi. A cutting element is carried by the balloon.

GOEKEN KARA; LAREAU RAYMOND; CHEN FUH-SHENG; WU SHOW-MEAN

210

MULTI-LAYER MEDICAL BALLOONS  

UK PubMed Central (United Kingdom)

The invention relates to multi-layer medical balloons. In one aspect, a medicaldevice includes an inflatable balloon. The inflatable balloon includes a firstlayer including a material having a first modulus of elasticity, and a secondlayer adjacent the first layer, the second layer including a material havinga second modulus of elasticity that differs from the first modulus of elasticityby at least about 2,000 psi. A cutting element is carried by the balloon.

GOEKEN Kara; LAREAU Raymond; CHEN Fuh-Sheng; WU Show-Mean

211

Thermally induced delamination of multilayers  

DEFF Research Database (Denmark)

Steady-state delamination of multilayered structures, caused by stresses arising during processing due to thermal expansion mismatch, is analyzed by a fracture mechanics model based on laminate theory. It is found that inserting just a few interlayers with intermediate thermal expansion coefficients may be an effective way of reducing the delamination energy release rate. Uneven layer thickness and increasing elastic mismatch are shown to raise the energy release rate. Experimental work confirms important trends of the model.

SØrensen, Bent F.; Sarraute, S.

1998-01-01

212

75 FR 79019 - Multilayered Wood Flooring From China  

Science.gov (United States)

...731-TA-1179 (Preliminary)] Multilayered Wood Flooring From China Determinations On the basis...imports from China of multilayered wood flooring, provided for in subheadings 4409...manufacturers of multilayered wood flooring. The following companies are...

2010-12-17

213

76 FR 76435 - Multilayered Wood Flooring From China  

Science.gov (United States)

...731-TA-1179 (Final)] Multilayered Wood Flooring From China Determinations On the basis...imports from China of multilayered wood flooring, provided for in subheadings 4409...manufacturers of multilayered wood flooring. The following companies are...

2011-12-07

214

Electrical Conductivity of Collapsed Multilayer Graphene Tubes  

Directory of Open Access Journals (Sweden)

Full Text Available Synthesis of multilayer graphene on copper wires by a chemical vapor deposition method is reported. After copper etching, the multilayer tube collapses forming stripes of graphitic films, their electrical conductance as a function of temperature indicate a semiconductor-like behavior. Using the multilayer graphene stripes, a cross junction is built and owing to its electrical behavior we propose that a tunneling process exists in the device.

D. Mendoza

2012-01-01

215

[Treatment of recurrent furunculosis].  

UK PubMed Central (United Kingdom)

The management of recurrent furunculosis is difficult, and often disappointing. We present the case of a 23-year-old female patient suffering from recurrent furunculosis. The furunculosis persisted after treatment with mupirocin nasal ointment, chlorhexidine soap and instructions for washing clothes, towels and bed sheets for a period of 7 days. Treatment with low-dose clindamycin for three months ultimately proved successful. We propose a structural approach for recurrent furunculosis in which extensive history-taking is followed by appropriate tests. Before prescribing an oral antibiotic (preferably low-dose clindamycin or a macrolide for 3 months), the patient should use an antimicrobial nasal ointment and soap and follow hygienic instructions as mentioned above. Members of the household who also have signs of the infection should be treated. Hygienic education is an essential component of treatment. We believe that this approach will lead to a treatment that is more effective and efficient.

Engelhard EA; Spanjaard L; Stijnis CK

2013-01-01

216

Multilayered Transducers Using Polyurea Film  

Science.gov (United States)

We have been investigating ultrasonic transducers using a polyurea piezoelectric material, which is fabricated by vapor deposition. To enhance the transducer performance, a multilayered configuration is studied in this work. First, the fabrication and transducer design of the multilayered structure are described. A special twin-vacuum chamber is used for laminating the polyurea layers and aluminum electrodes alternately without breaking vacuum. We fabricate two- and four-layered transducers with 1.5 ?m polyurea films. The calculation results show that the force factor and electromechanical coupling coefficient increase as the number of layers increases. Second, to evaluate the transducer performance, we measure the electromechanical coupling factors and electric admittances. The coupling coefficients also increase as the number of layers increases at the resonant frequencies of about 30, 65, and 100 MHz. The pulse/echo measurements are conducted to determine the transmission and receiving characteristics using a reflector. The results of the experiment show that the voltage amplitudes of the received signal increase because of multilayer lamination.

Nakazawa, Marie; Tabaru, Masaya; Nakamura, Kentaro; Ueha, Sadayuki; Maezawa, Akihiro

2007-07-01

217

Recurrent Pneumonia in Children  

Directory of Open Access Journals (Sweden)

Full Text Available Objective: The aim of this study was to determine the relative frequency and describe the predisposing causes of recurrent pneumonia in children. Material and methods: We retrospectively reviewed the medical records of patients with pneumonia at Uludag University Medical Faculty, Department of Pediatrics, between January 1998 and December 2007. Recurrent pneumonia was defined as at least two episodes in a 1 year period or at least three episodes over a lifetime. Patients with recurrent pneumonia were included in this study.Results: During the study period, 1617 children were admitted to hospital with a diagnosis of pneumonia, 185 (11.4%) met the criteria for recurrent pneumonia. The mean age of patients was 16±32 months (3 months-14 years) and 61% were male. An underlying cause was identified in 143 patients (77%). Of these, the underlying cause was diagnosed prior the pneumonia in 25 patients (17%), during the first episode in 30 (21%), and during recurrence in 88 (62%). Underlying causes included congenital cardiac defects in 32 patients (17.2%), gastroesophageal reflux in 31 patients (16.7%), aspiration syndrome in 27 patients (14.5%), asthma in 16 patients (8.6%), cystic fibrosis in 12 patients (6.4%) immune disorders in 10 patients (5.4%), tuberculosis in 9 patients (4.8%) and anomalies of the chest and lung in 6 patients (3.2%). No predisposing illness could be demonstrated in 42 patients (33%). Conclusion: Recurrent pneumonia occurred in 11.4% of all children hospitalized for pneumonia. The underlying cause was identified in 77% of the children. The most common causes were congenital cardiac defects, gastroesophageal reflux and aspiration syndrome.

Solmaz Çelebi; Mustafa Hac?mustafao?lu; Yücehan Albayrak; Nurcan Bulur

2010-01-01

218

Recurrent parotitis in children  

Directory of Open Access Journals (Sweden)

Full Text Available Recurrent parotitis is an uncommon condition in children. Its etiological factors have not been proved till date although causes due to genetic inheritance, local autoimmune manifestation, allergy, viral infection and immunodeficiency have been suggested. The exact management of this disorder is not yet standardized, but a conservative approach is preferred and all affected children should be screened for Sjogren?s syndrome and immune deficiency including human immunodeficiency virus. We report a 12 years female child who presented with 12 episodes of non-painful recurrent swellings of the bilateral parotid gland in the past 3 years.

Bhattarai M; Wakode P

2006-01-01

219

Learning temporal dependencies in connectionist speech recognition  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Hybrid connectionist/HMM systems model time using both a Markov chain and through properties of a connectionist network. In this paper, we discuss the nature of the time dependence currently employed in our systems using recurrent networks (RNs) and feed-forward multi-layer perceptrons (MLPs). In pa...

Renals, Steve; Hochberg, Mike; Robinson, Tony

220

Recurrent pelvic surgery.  

UK PubMed Central (United Kingdom)

Recurrent pelvic surgery is technically challenging. This article discusses this complex topic in patients with both benign and malignant disease. Perspectives regarding a safe approach to patients who may require reoperative pelvic surgery are discussed with a focus on work-up, technical approach, and the importance of an experienced multidisciplinary team.

Boostrom SY; Dozois EJ

2013-02-01

 
 
 
 
221

Idiopathic recurrent pneumoparotitis.  

UK PubMed Central (United Kingdom)

Parotid swelling in a child can represent any of a variety of pathologies, including lymphadenitis, autoimmune disorders, other inflammatory conditions, vascular malformations, or neoplasms. Parotitis is usually infectious in etiology and is generally treated with antibiotics and supportive management. We report a case of a child with recurrent idiopathic pneumoparotitis, and a review of literature and the disease process is provided.

McCormick ME; Bawa G; Shah RK

2013-03-01

222

Idiopathic recurrent pneumoparotitis.  

Science.gov (United States)

Parotid swelling in a child can represent any of a variety of pathologies, including lymphadenitis, autoimmune disorders, other inflammatory conditions, vascular malformations, or neoplasms. Parotitis is usually infectious in etiology and is generally treated with antibiotics and supportive management. We report a case of a child with recurrent idiopathic pneumoparotitis, and a review of literature and the disease process is provided. PMID:23318047

McCormick, Michael E; Bawa, Gurneet; Shah, Rahul K

2013-01-12

223

Recurrent infective endocarditis.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Infective endocarditis is a serious disease associated with high mortality. Patients surviving recurrent bouts of infective endocarditis are reported infrequently. We report on a non-drug abuser patient who experienced seven episodes of infective endocarditis--the largest number reported to our know...

Lossos, I. S.; Oren, R.

224

Proximity effect of superconducting multilayer films  

Energy Technology Data Exchange (ETDEWEB)

The proximity effect of superconducting multilayer films consisting of different metals is considered. Using Silvert and Cooper's method, an approximate relationship between the critical temperature of a multilayered heterogeneous film and its structure is given under the Cooper limit.

Cai, X.; Yin, D.

1982-04-01

225

Coherent multilayer crystals and method of making  

Energy Technology Data Exchange (ETDEWEB)

A new material is described consisting of a coherent multilayer crystal of two or more elements where each layer is composed of a single element. Each layer may vary in thickness from about 2 A to 2500 A. The multilayer crystals are prepared by sputter deposition under conditions which slow the sputtered atoms to near substrate temperatures before they contact the substrate.

Schuller, I.K.; Falco, C.M.

1980-10-30

226

Multilayers for soft X-ray optics  

Energy Technology Data Exchange (ETDEWEB)

Optical elements for soft X-ray radiation are required for a wide variety of applications. Multilayer thin films are currently used for some of these applications, and they show potential for many others. The author review the operating and design principles of multilayer soft X-ray mirrors, causes for reflectance losses, fabrication requirements, and characterization and testing procedures.

Fernandez, F.E.; Falco, C.M.

1988-08-01

227

Method of making coherent multilayer crystals  

Energy Technology Data Exchange (ETDEWEB)

A new material consisting of a coherent multilayer crystal of two or more elements where each layer is composed of a single element. Each layer may vary in thickness from about 2 A to 2500 A. The multilayer crystals are prepared by sputter deposition under conditions which slow the sputtered atoms to near substrate temperatures before they contact the substrate.

Schuller, I.K.; Falco, C.M.

1984-02-07

228

Method of making coherent multilayer crystals  

Energy Technology Data Exchange (ETDEWEB)

A new material consisting of a coherent multilayer crystal of two or more elements where each layer is composed of a single element. Each layer may vary in thickness from about 2 .ANG. to 2500 .ANG.. The multilayer crystals are prepared by sputter deposition under conditions which slow the sputtered atoms to near substrate temperatures before they contact the substrate.

Schuller, Ivan K. (Woodridge, IL); Falco, Charles M. (Woodridge, IL)

1984-01-01

229

Figure correction of multilayer coated optics  

Energy Technology Data Exchange (ETDEWEB)

A process is provided for producing near-perfect optical surfaces, for EUV and soft-x-ray optics. The method involves polishing or otherwise figuring the multilayer coating that has been deposited on an optical substrate, in order to correct for errors in the figure of the substrate and coating. A method such as ion-beam milling is used to remove material from the multilayer coating by an amount that varies in a specified way across the substrate. The phase of the EUV light that is reflected from the multilayer will be affected by the amount of multilayer material removed, but this effect will be reduced by a factor of 1-n as compared with height variations of the substrate, where n is the average refractive index of the multilayer.

Chapman; Henry N. (Livermore, CA), Taylor; John S. (Livermore, CA)

2010-02-16

230

Recurrent Oral Thrush.  

UK PubMed Central (United Kingdom)

Autoimmune polyendocrinopathy syndrome type 1 (APS-1) is characterized by the presence of at least two out of three clinical features, which include chronic mucocutaneous candidiasis (CMC), Addison's disease and hypoparathyroidism. The authors' present an one and a half year old girl with recurrent oral thrush who presented with generalised afebrile seizure. Evaluation revealed severe hypocalcemia with low parathormone and normal vitamin D level consistent with hypoparathyroidism. In view of the oral candidiasis and hypoparathyroidism, a clinical possibility of autoimmune polyglandular syndrome (type 1) was strongly considered. Her mother, on subsequent pregnancy was subjected to gene analysis of the fetus (chorionic villus sampling) and also for this child (index case). Both the fetus and index child were confirmed to have the AIRE gene mutation of APS1. After detailed counseling the parents opted for medical termination of the pregnancy. In children who present with recurrent oral thrush we need to consider but also look beyond immunodeficiency.

Sivabalan S; Mahadevan S; Srinath MV

2013-10-01

231

Prevention of recurrent nephrolithiasis.  

Science.gov (United States)

The first episode of nephrolithiasis provides an opportunity to advise patients about measures for preventing future stones. Low fluid intake and excessive intake of protein, salt and oxalate are important modifiable risk factors for kidney stones. Calcium restriction is not useful and may potentiate osteoporosis. Diseases such as hyperparathyroidism, sarcoidosis and renal tubular acidosis should be considered in patients with nephrolithiasis. A 24-hour urine collection with measurement of the important analytes is usually reserved for use in patients with recurrent stone formation. In these patients, the major urinary risk factors include hypercalciuria, hyperoxaluria, hypocitraturia and hyperuricosuria. Effective preventive and treatment measures include thiazide therapy to lower the urinary calcium level, citrate supplementation to increase the urinary citrate level and, sometimes, allopurinol therapy to lower uric acid excretion. Uric acid stones are most often treated with citrate supplementation. Data now support the cost-effectiveness of evaluation and treatment of patients with recurrent stones. PMID:10593318

Goldfarb, D S; Coe, F L

1999-11-15

232

Chronic recurrent multifocal osteomyelitis.  

UK PubMed Central (United Kingdom)

Chronic recurrent multifocal osteomyelitis is a rare auto-inflammatory condition that primarily affects children and adolescents. It presents with recurrent episodes of pain related to the presence of foci of sterile bone inflammation. The long bones of the lower extremities are more frequently affected and the spine can also be involved. Imaging studies, including whole-body magnetic resonance, are important for diagnosis and detection of asymptomatic lesions. Bone biopsies may be necessary to exclude other diseases, including malignancy and infections. Non-steroidal anti-inflammatory drugs cause relief of symptoms in the majority of cases. Bisphosphonates and TNF-? blockers are alternatives for patients who do not respond or who have spinal involvement.

Costa-Reis P; Sullivan KE

2013-08-01

233

Chemotherapy in recurrent ependymoma.  

Science.gov (United States)

Surgical resection with or without radiation therapy confers long-term remission in approximately half of the patients newly diagnosed with ependymoma. Chemotherapy has a limited role in the management of ependymoma. In newly diagnosed infants, chemotherapy is utilized as an attempt to defer radiation. The use of chemotherapy in older children has provided no conclusive benefit. The largest experience with chemotherapy in ependymoma has been in children with recurrent disease. In this section, we will analyze the principal institutional and cooperative group phase I, phase II, and phase III clinical trials utilizing single-agent and multiagent chemotherapy in patients with recurrent ependymoma. In addition, future directions relating to novel medical oncologic therapies will also be discussed. PMID:9782208

Siffert, J; Allen, J C

1998-06-01

234

Chemotherapy in recurrent ependymoma.  

UK PubMed Central (United Kingdom)

Surgical resection with or without radiation therapy confers long-term remission in approximately half of the patients newly diagnosed with ependymoma. Chemotherapy has a limited role in the management of ependymoma. In newly diagnosed infants, chemotherapy is utilized as an attempt to defer radiation. The use of chemotherapy in older children has provided no conclusive benefit. The largest experience with chemotherapy in ependymoma has been in children with recurrent disease. In this section, we will analyze the principal institutional and cooperative group phase I, phase II, and phase III clinical trials utilizing single-agent and multiagent chemotherapy in patients with recurrent ependymoma. In addition, future directions relating to novel medical oncologic therapies will also be discussed.

Siffert J; Allen JC

1998-06-01

235

Penalizing null recurrent diffusions  

CERN Multimedia

We present some limit theorems for the normalized laws (with respect to functionals involving last passage times at a given level up to time t) of a large class of null recurrent diffusions. Our results rely on hypotheses on the L\\'evy measure of the diffusion inverse local time at 0. As a special case, we recover some of the penalization results obtained by Najnudel, Roynette and Yor in the (reflected) Brownian setting.

Profeta, Christophe

2011-01-01

236

Recurrent maturing perineal lipoblastoma  

International Nuclear Information System (INIS)

Lipoblastoma is a rare benign neoplasm of fetal adipose tissue that we see mostly in infants and young children less than 3 years of age. Most lipoblastomas occur on the extremities, trunk, head and neck, and various other organs have been described. We report a case of a recurrent perineal lipoblastoma in a 2.5-year-old boy, which showed maturation of the lipoblasts as compared to the primary tumor. (author)

2005-01-01

237

Recurrent maturing perineal lipoblastoma.  

UK PubMed Central (United Kingdom)

Lipoblastoma is a rare benign neoplasm of fetal adipose tissue that we see mostly in infants and young children less than 3 years of age. Most lipoblastomas occur on the extremities, trunk, head and neck, and various other organs have been described. We report a case of a recurrent perineal lipoblastoma in a 2.5-year-old boy, which showed maturation of the lipoblasts as compared to the primary tumor.

Al-Momani HM

2005-11-01

238

Recurrent carpal tunnel syndrome.  

Science.gov (United States)

Carpal tunnel release is a common procedure with a high rate of alleviating the patient's symptoms. The incidence of recurrent or persistent carpal tunnel syndrome is rare, although likely underestimated. Complaints of worsening numbness, tingling, or weakness should alert the physician to possible nerve injury and need for early exploration. The overall results of revision carpal tunnel procedures are less successful than primary surgery; however, surgery should be performed when indicated, as it may alleviate or improve symptoms. PMID:23895723

Mosier, Brian A; Hughes, Thomas B

2013-06-27

239

Recurrent carpal tunnel syndrome.  

UK PubMed Central (United Kingdom)

Carpal tunnel release is a common procedure with a high rate of alleviating the patient's symptoms. The incidence of recurrent or persistent carpal tunnel syndrome is rare, although likely underestimated. Complaints of worsening numbness, tingling, or weakness should alert the physician to possible nerve injury and need for early exploration. The overall results of revision carpal tunnel procedures are less successful than primary surgery; however, surgery should be performed when indicated, as it may alleviate or improve symptoms.

Mosier BA; Hughes TB

2013-08-01

240

Recurrent urinary tract infection.  

UK PubMed Central (United Kingdom)

OBJECTIVE: to provide an update of the definition, epidemiology, clinical presentation, investigation, treatment, and prevention of recurrent urinary tract infections in women. OPTIONS: continuous antibiotic prophylaxis, post-coital antibiotic prophylaxis, and acute self-treatment are all efficient alternatives to prevent recurrent urinary tract infection. Vaginal estrogen and cranberry juice can also be effective prophylaxis alternatives. EVIDENCE: a search of PubMed and The Cochrane Library for articles published in English identified the most relevant literature. Results were restricted to systematic reviews, randomized control trials/controlled clinical trials, and observational studies. There were no date restrictions. VALUES: this update is the consensus of the Sub-Committee on Urogynaecology of the Society of Obstetricians and Gynaecologists of Canada. Recommendations were made according to the guidelines developed by the Canadian Task Force on Preventive Health Care (Table 1). OPTIONS: recurrent urinary tract infections need careful investigation and can be efficiently treated and prevented. Different prophylaxis options can be selected according to each patient's characteristics.

Epp A; Larochelle A; Lovatsis D; Walter JE; Easton W; Farrell SA; Girouard L; Gupta C; Harvey MA; Robert M; Ross S; Schachter J; Schulz JA; Wilkie D; Ehman W; Domb S; Gagnon A; Hughes O; Konkin J; Lynch J; Marshall C; Society of Obstetricians and Gynaecologists of Canada

2010-11-01

 
 
 
 
241

Bevacizumab for recurrent ependymoma.  

UK PubMed Central (United Kingdom)

BACKGROUND: Ependymoma is a rare type of glioma, representing 5% of all CNS malignancies. Radiotherapy (RT) is commonly administered, but there is no standard chemotherapy. At recurrence, ependymoma is notoriously refractory to therapy and the prognosis is poor. In recurrent glioblastoma, encouraging responses with bevacizumab have been observed. METHODS: In this Institutional Review Board-approved study, we retrospectively analyzed the records of 8 adult patients treated for recurrent ependymoma and anaplastic ependymoma with bevacizumab containing chemotherapy regimens. We determined radiographic response (Macdonald criteria), median time to progression (TTP), and median overall survival (OS; Kaplan-Meier method). RESULTS: There were 4 men and 4 women with a median age of 40 years (range, 20-65). Prior treatment included surgery (n = 8), RT (8), temozolomide (5), and carboplatin (4). Bevacizumab (5-15 mg/kg every 2-3 weeks) was administered alone (2) or concurrently with cytotoxic chemotherapy including irinotecan (3), carboplatin (2), or temozolomide (1). Six patients achieved a partial response (75%) and 1 remained stable for over 8 months. Median TTP was 6.4 months (95% confidence interval 1.4-7.4) and median OS was 9.4 months (95% confidence interval 7.0-not reached), with a median follow-up of 5.2 months among 5 surviving patients (63%). CONCLUSIONS: The radiographic response rate to bevacizumab-containing regimens is high. A prospective study is warranted.

Green RM; Cloughesy TF; Stupp R; DeAngelis LM; Woyshner EA; Ney DE; Lassman AB

2009-11-01

242

Recurrent meningitis in children.  

UK PubMed Central (United Kingdom)

Recurrent meningitis in children, although rare, results in an increased risk of acute complications and long-term morbidity. We did a retrospective case series to analyze the clinical presentation, predisposing factors, treatment and outcome of children with recurrent meningitis admitted at Shifa International hospital, Islamabad. All children presenting with recurrent meningitis from December 2006 to May 2011 were included in the study. There were a total of 8 children with a mean age of 6 +/- 2.97 years (2-10 years). Majority (87%) were males. There was an average of 4 +/- 4.92 (2-9) episodes of meningitis in each patient. Fever with vomiting was the most common (87%) presenting symptom, followed by seizures (62%) and headache (50%). The underlying etiology was confirmed on CSF analysis, computed tomography scan (CT) and magnetic resonance imaging (MRI). About half of them had history of head trauma. All responded to antibiotics and six needed surgery. On follow up, 2 (25%) children had some neurological impairment.

Khan EA; Choudhry S; Roohullah M; Hashmi I; Nazir R

2013-02-01

243

Perceptron Learning of SAT  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Boolean satisfiability (SAT) as a canonical NP-complete decision problem is one of the most important problems in computer science. In practice, real-world SAT sentences are drawn from a distribution that may result in efficient algorithms for their solution. Such SAT instances are likely to have sh...

Flint, Alex; Blaschko, Matthew

244

Polyelectrolyte multilayers in tissue engineering.  

UK PubMed Central (United Kingdom)

The layer-by-layer assembly of sequentially adsorbed, alternating polyelectrolytes has become increasingly important over the past two decades. The ease and versatility in assembling polyelectrolyte multilayers (PEMs) has resulted in numerous wide ranging applications of these materials. More recently, PEMs are being used in biological applications ranging from biomaterials, tissue engineering, regenerative medicine, and drug delivery. The ability to manipulate the chemical, physical, surface, and topographical properties of these multilayer architectures by simply changing the pH, ionic strength, thickness, and postassembly modifications render them highly suitable to probe the effects of external stimuli on cellular responsiveness. In the field of regenerative medicine, the ability to sequester growth factors and to tether peptides to PEMs has been exploited to direct the lineage of progenitor cells and to subsequently maintain a desired phenotype. Additional novel applications include the use of PEMs in the assembly of three-dimensional layered architectures and as coatings for individual cells to deliver tunable payloads of drugs or bioactive molecules. This review focuses on literature related to the modulation of chemical and physical properties of PEMs for tissue engineering applications and recent research efforts in maintaining and directing cellular phenotype in stem cell differentiation.

Detzel CJ; Larkin AL; Rajagopalan P

2011-04-01

245

[Postoperative recurrence of spontaneous pneumothorax].  

Science.gov (United States)

Few reports on recurrence after thoracoscopic bullectomy for spontaneous pneumothorax specify the follow-up period and follow-up ratio. Because of the variation in follow-up periods, many reported recurrence rates were not comparable. Some reports compared simple recurrence rate (number of recurrent cases/number of operated cases) of different groups with different follow-up periods. In this study, we employ the Kaplan-Meier method along with a set of optimal follow-up periods and ratios in order to determine a more reliable recurrence rate. Consecutive 68 patients (74 surgical procedures) underwent thoracoscopic bullectomy for spontaneous pneumothorax at our institution between November 2000 and December 2005. A follow-up survey was conducted by phone to determine the rate of recurrent pneumothorax. The follow-up ratio and the mean follow-up period were 92.6% and 1,316 +/- 481 days, respectively. Postoperative recurrence was confirmed for 4 patients. The interval up to recurrence was 144, 345, 476 and 616 days after the bullectomy, respectively. All cases of recurrent pneumothorax occurred within 2 years following the bullectomy. The 1-year, 2-year and 3-year cumulative recurrence rate was 3.0%, 6.3% and 6.3%, respectively. In light of these findings, we feel that comparison analysis of pneumothorax recurrence rates should be evaluated using the Kaplan-Meier method, furthermore, our data suggests that a follow-up period of 2 or more years is advisable. PMID:19048897

Ono, K; Nagashima, A; Inaba, G; Iwanami, T; Yasumoto, K

2008-11-01

246

Terbium-Based Extreme Ultraviolet Multilayers  

Energy Technology Data Exchange (ETDEWEB)

We have fabricated periodic multilayers that comprise either Si/Tb or SiC/Tb bilayers, designed to operate as narrowband reflective coatings near 60 nm wavelength in the extreme ultraviolet (EUV). We find peak reflectance values in excess of 20% near normal incidence. The spectral bandpass of the best Si/Tb multilayer was measured to be 6.5 nm full width at half-maximum (FWHM), while SiC/Tb multilayers have a more broad response, of order 9.4 nm FWHM. Transmission electron microscopy analysis of Si/Tb multilayers reveals polycrystalline Tb layers, amorphous Si layers, and relatively large asymmetric amorphous interlayers. Thermal annealing experiments indicate excellent stability to 100 C (1 h) for Si/Tb. These new multilayer coatings have the potential for use in normal incidence instrumentation in a region of the EUV where efficient narrowband multilayers have not been available until now. In particular, reflective Si/Tb multilayers can be used for solar physics applications where the coatings can be tuned to important emission lines such as O V near 63.0 nm and Mg X near 61.0 nm.

Windt,D.; Seely, J.; Kjornrattanawich, B.; Uspenskii, Y.

2005-01-01

247

Magnetic properties of Ni/Pt multilayers  

International Nuclear Information System (INIS)

We have grown Ni/Pt multilayers with Pt buffer layer, by evaporation under UHV conditions on glass substrates maintained at 300 K. The magnetic properties of Ni/Pt multilayers are examined as a function of Ni layer thickness t Ni. The temperature dependence of the spontaneous magnetization M(T) is well described by a T 3/2 law in all multilayers. A spin-wave theory has been used to explain the temperature dependence of the magnetization and the approximate values for the bulk exchange interaction J b, surface exchange interaction J S and the interlayer coupling strength J I for various Ni layer thicknesses have been obtained.

2005-01-15

248

Enhanced performance of EUV multilayer coatings  

Science.gov (United States)

Reported is a summary of the development of EUV Mo/Si multilayer coating technology. Though the results are developed for application in Extreme Ultraviolet Lithography, they are of a broader relevance including optics for astronomy. The coating process used consists of electron beam evaporation in combination with low energy ion beam smoothening. The radiation hardness of these coatings is discussed and methods to reduce the multilayer induced substrate stress. The reflectance of the coatings, which are covered with a special protective capping layer, is typically around 65%, while the non correctable figure error added by the full multilayer stack is controlled to better than 15 picometer.

Louis, E.; Yakshin, A. E.; Zoethout, E.; van de Kruijs, R. W. E.; Nedelcu, I.; van der Westen, S. A.; Tsarfati, T.; Bijkerk, F.; Enkisch, H.; Müllender, S.; Wolschrijn, B.; Mertens, B.

2005-08-01

249

LPCVD tungsten multilayer metallization for VLSI systems  

International Nuclear Information System (INIS)

Multilayer metalization enables shorter interconnects, ease of design and yet higher packing density for VLSI circuits. Experiments showed that LPCVD tungsten films deposited in a cold-wall reactor have good uniformity, high purity, low resistivity, low stress, good adherence and are readily patterned into high resolution lines. A multilayer interconnect system consisting of three layers of tungsten metallization followed by a fourth layer of aluminum metallization has been designed, fabricated and tested. Low ohmic contacts were achieved along with excellent step coverage. CMOS devices and logic gates were successfully fabricated and tested using tungsten multilayer metalization schemes

1986-01-01

250

[Recurrent left atrial myxoma].  

UK PubMed Central (United Kingdom)

Primary cardiac tumors are rare. Mixomas are the most common among them; 75% are located in the left atrium, 20% in the right atrium, and the rest in the ventricles. The seldom appear in atrio-ventricular valves. Recidivant mixoma are also rare, appearing in 1-5% of all patients that have undergone surgical treatment of a mixoma. In this paper we present our experience with a female patient, who 8 years after having been operated of a left atrial mixoma, began with symptoms of mild heart failure. Transthoracic echocardiography revealed recurrence of the tumor, and was therefore subjected to a second open-heart surgery from which she recovered without complications.

Moreno Martínez FL; Lagomasino Hidalgo A; Mirabal Rodríguez R; López Bermúdez FH; López Bernal OJ

2003-10-01

251

Chronic recurrent multifocal osteomyelitis  

International Nuclear Information System (INIS)

CRMO is a particular form of osteomyelitis in children which may also affect adolescents, and which may persist into adult age. CRMO differs from the conventional forms of OM through the multifocal involvement of the skeleton, a chronic course with recurrences and new lesions occurring unpredictably in various sites. Symptoms are rather mild. The histopathology is non-characteristic, the etiology unknown. Long term prognosis is favourable in spite of the lack of any specific therapy. The radiological appearances are essential for the diagnosis. The present report is aimed as a contribution to the knowledge of this recently established disease entity. (orig.).

1984-01-01

252

Recurrent cutaneous leishmaniasis.  

UK PubMed Central (United Kingdom)

We present a case of an 18-year-old male patient who, after two years of inappropriate treatment for cutaneous leishmaniasis, began to show nodules arising at the edges of the former healing scar. He was immune competent and denied any trauma. The diagnosis of recurrent cutaneous leishmaniasis was made following positive culture of aspirate samples. The patient was treated with N-methylglucamine associated with pentoxifylline for 30 days. Similar cases require special attention mainly because of the challenges imposed by treatment.

Gomes CM; Damasco Fdos S; de Morais OO; de Paula CD; Sampaio RN

2013-05-01

253

Multilayer coatings on figured optics  

Energy Technology Data Exchange (ETDEWEB)

Soft X-Ray Projection Lithography (SXPL) will reqire uniform, high reflectivity multilayer (ML) coatings on figured optical surfaces with lens speeds (f{sup {number sign}}) between 3 and 6 and diameters of 10 to 15 cm. High reflectivity Mo-Si ML coatings for operation near 13 nm were deposited on f{sup {number sign}}3.4 and f{sup {number sign}}6 optics 5 and 7.5 cm in diameter using planar DC magnetron sputtering. Measurements of the normal incidence reflectivity (NIR) of 63% at 13 nm uniform over the central 5 cm of the figured surface were obtained. Comparison of the measured values to model calculations of the wavelength dependent reflectivity indicate that the ML period is uniform to better than 0.04 nm over thiS region. 7 refs.

Vernon, S.P. (Vernon Applied Physics, Torrance, CA (United States)); Stearns, D.G.; Rosen, R.S.; Ceglio, N.M.; Gaines, D.P. (Lawrence Livermore National Lab., CA (United States)); Krumrey, M.; Mueller, P. (Physikalisch-Technische Bundesanstalt, Berlin (Germany). VUV Radiometric Lab.)

1991-07-01

254

Multilayer coatings on figured optics  

Energy Technology Data Exchange (ETDEWEB)

Soft X-Ray Projection Lithography (SXPL) will reqire uniform, high reflectivity multilayer (ML) coatings on figured optical surfaces with lens speeds (f{sup {number_sign}}) between 3 and 6 and diameters of 10 to 15 cm. High reflectivity Mo-Si ML coatings for operation near 13 nm were deposited on f{sup {number_sign}}3.4 and f{sup {number_sign}}6 optics 5 and 7.5 cm in diameter using planar DC magnetron sputtering. Measurements of the normal incidence reflectivity (NIR) of 63% at 13 nm uniform over the central 5 cm of the figured surface were obtained. Comparison of the measured values to model calculations of the wavelength dependent reflectivity indicate that the ML period is uniform to better than 0.04 nm over thiS region. 7 refs.

Vernon, S.P. [Vernon Applied Physics, Torrance, CA (United States); Stearns, D.G.; Rosen, R.S.; Ceglio, N.M.; Gaines, D.P. [Lawrence Livermore National Lab., CA (United States); Krumrey, M.; Mueller, P. [Physikalisch-Technische Bundesanstalt, Berlin (Germany). VUV Radiometric Lab.

1991-07-01

255

Iwasawa effects in multilayer optics.  

Science.gov (United States)

There are many two-by-two matrices in layer optics. It is shown that they can be formulated in terms of a three-parameter group whose algebraic property is the same as the group of Lorentz transformations in a space with two spacelike and one timelike dimensions, or the Sp(2) group which is a standard theoretical tool in optics. Among the interesting mathematical properties of this group, the Iwasawa decomposition drastically simplifies the matrix algebra under certain conditions, and leads to a concise expression for the S matrix for transmitted and reflected waves. It is shown that the Iwasawa effect can be observed in multilayer optics, and a sample calculation of the S matrix is given. PMID:11497725

Georgieva, E; Kim, Y S

2001-07-10

256

Gilbert Damping in Magnetic Multilayers  

CERN Multimedia

We study the enhancement of the ferromagnetic relaxation rate in thin films due to the adjacent normal metal layers. Using linear response theory, we derive the dissipative torque produced by the s-d exchange interaction at the ferromagnet-normal metal interface. For a slow precession, the enhancement of Gilbert damping constant is proportional to the square of the s-d exchange constant times the zero-frequency limit of the frequency derivative of the local dynamic spin susceptibility of the normal metal at the interface. Electron-electron interactions increase the relaxation rate by the Stoner factor squared. We attribute the large anisotropic enhancements of the relaxation rate observed recently in multilayers containing palladium to this mechanism. For free electrons, the present theory compares favorably with recent spin-pumping result of Tserkovnyak et al. [Phys. Rev. Lett. \\textbf{88},117601 (2002)].

Simanek, E

2002-01-01

257

Iwasawa effects in multilayer optics.  

UK PubMed Central (United Kingdom)

There are many two-by-two matrices in layer optics. It is shown that they can be formulated in terms of a three-parameter group whose algebraic property is the same as the group of Lorentz transformations in a space with two spacelike and one timelike dimensions, or the Sp(2) group which is a standard theoretical tool in optics. Among the interesting mathematical properties of this group, the Iwasawa decomposition drastically simplifies the matrix algebra under certain conditions, and leads to a concise expression for the S matrix for transmitted and reflected waves. It is shown that the Iwasawa effect can be observed in multilayer optics, and a sample calculation of the S matrix is given.

Georgieva E; Kim YS

2001-08-01

258

RECURRENT INTESTINAL CANDIDOSIS  

Directory of Open Access Journals (Sweden)

Full Text Available The prevalence of recurrent intestinal candidosis (RIC) has been increasing in recent years. The aim of the study was to investigate the prevalence of some Candida species in etiology of RIC and to examine their antifungal susceptibility. The study involved 70 patients with RIC. The patients were selected according to criteria that in the previous six months they had minimum two microbiological findings of the same Candida species in feces, as well as the symptoms and clinical signs of the digestive tract infection (nausea, disgust, borborygmus, bloating, mushy stool, appearance of mucus in feces). Candida spp. were isolated using a standard procedure. Candida albicans was (C. albicans) identified from other species by the germination test application. Non-albicans species were differentiated using a commercial CandiFast-test (Mycoplasma-International, France).After using the tests for yeast differentiation, C. albicans was found to be the most frequent cause of recurrent intestinal tract candidosis (45 patients - 64.29%). Other species were found in a significantly smaller number of patients (C. glabrata-4, C. crusei-4, C. kefyr-3, C. parapsilosis-1, C. guillermondil-1, C. tropicalis-1, C. lusiniae-1). The isolated yeasts showed good susceptibility to amphotericin B, nystatine, 5-fluorocytosine and ketoconazole, while higher percent of isolated species was resistant to econazole, miconazole and fluconazole.Species C. albicans is the most common cause of RIC.

Suzana Tasic; Natasa Miladinovic-Tasic; Jovana Djordjevic; Dragan Zdravkovic; Drenka Paunovic-Todosijevic

2008-01-01

259

Electron transmission in one dimensional multilayer material  

Energy Technology Data Exchange (ETDEWEB)

Using simple assumptions, it is possible to study the transmission of a monoenergetic parallel electron beam in a one dimensional multilayer material, knowing experimental or Monte Carlo results obtained in homogeneous media.

Millet, M.; Pierronne, F.

1983-07-01

260

Soft X-ray multilayers and filters  

CERN Multimedia

The periodic and non-periodic multilayers were designed by using a random number to change each layer and a suitable merit function. Ion beam sputtering and magnetron sputtering were used to fabricate various multilayers and beam splitters in soft X-ray range. The characterization of multilayers by small angle X-ray diffraction, Auger electron spectroscopy, Rutherford back scattering spectroscopy and reflectivity illustrated the multilayers had good structures and smooth interlayers. The reflectivity and transmission of a beam splitter is about 5%. The fabrication and transmission properties of Ag, Zr were studied. The Rutherford back scattering spectroscopy and auger electron spectroscopy were used to investigate the contents and distributions of impurities and influence on qualities of filters. The attenuation coefficients were corrected by the data obtained by measurements

Wang Zhan Shan; Tang Wei Xing; Qin Shuji; Zhou Bing; Chen Ling Ya

2002-01-01

 
 
 
 
261

Synthesis and evaluation of thermoelectric multilayer films  

Energy Technology Data Exchange (ETDEWEB)

The deposition of compositionally modulated (Bi{sub 1-x}Sb{sub x}){sub 2}(Te{sub 1-y}Se{sub y}){sub 3} thermoelectric multilayer films by magnetron sputtering has been demonstrated. Structures with a period of 140{Angstrom} are shown to be stable to interdiffusion at the high deposition temperatures necessary for growth of single layer crystalline films with ZT {gt} 0.5. These multilayers are of the correct dimension to exhibit the electronic properties of quantum well structures. Furthermore it is shown that the Seebeck coefficient of the films is not degraded by the presence of this multilayer structure. It may be possible to synthesize a multilayer thermoelectric material with enhanced ZT by maximizing the barrier height through optimization of the composition of the barrier.

Wagner, A.V.; Foreman, R.J.; Summers, L.J.; Barbee, T.W. Jr.; Farmer, J.C.

1996-03-21

262

Irradiated multilayer film for primal meat packaging  

International Nuclear Information System (INIS)

This patent deals with a heat-shrinkable, multilayer film suitable for use in fabricating bags for packaging primal and sub-primal meat cuts and processed meats. The multilayer film has a first outer layer of an ethylene-vinyl acetate copolymer, a core layer of a barrier film comprising vinylidene chloride-methyl acrylate copolymer, and a second outer layer of an ethylene-vinyl acetate copolymer. The multilayer film is preferably made by co-extrusion of the layers, and then it is biaxially stretched. After biaxial stretching, the multilayer film is irradiated to a dosage level of between 1 megarad and 5 megarads and heat-sealed in the form of a bag. The bag has improved storage stability characteristics.

1985-06-14

263

Fabrication and Properties of Multilayer Structures.  

Science.gov (United States)

the goal of this program is to develop vapor desposition processes for application to integrated circuit technology, particularly multilayer applications. Its purpose is to investigate vapor deposition techniques that offer potential for synthesis of mate...

W. A. Tiller T. W. Barbee W. Dibble L. Nagel A. Savan

1981-01-01

264

Plasma etchback of multilayer printed wiring boards  

Energy Technology Data Exchange (ETDEWEB)

Removal of epoxy smear and glass fiber protrusions in multilayer printed wiring board holes was investigated. Gas plasma techniques, using a mixture of carbon tetrafluoride and oxygen, removed the eposies; however, the glass fibers were not affected.

Gentry, F.L.

1980-06-01

265

Schwinger pair creation in multilayer graphene  

CERN Multimedia

The low energy effective field model for the multilayer graphene (at ABC stacking) in external Electric field is considered. The Schwinger pair creation rate and the vacuum persistence probability are calculated using the semi - classical approach.

Zubkov, M A

2012-01-01

266

Exact solution of multilayered piezoelectric diaphragms.  

UK PubMed Central (United Kingdom)

This paper investigates dynamic behavior of multilayered piezoelectric diaphragms that are simplified as laminated plates. The validity of the dynamic analysis based on the simplified clamped multilayered plate model has first been studied using ANSYS finite element (FE)-codes. The simplified, clamped, multilayered plate model has been verified to be a reasonable one in comparison with the exact model. Subsequently, the frequency characteristics of clamped rectangular piezoelectric laminated plates were further analytically investigated. Using the classical laminated plate theory, mechanical, electrical, and electromechanical characteristics of the multilayered piezoelectric diaphragms were studied. For ease of calculation, the dimensionless method was adopted. Furthermore, numerical analysis was carried out using the Rayleigh-Ritz method. Influence of dimensions of the laminar diaphragm on nature frequencies also was studied. The thickness ratio of the PZT layer to the total thickness of the laminar diaphragm has been optimized to obtain the largest deflection.

Yao L; Lu L; Wang Z; Zhu W; Dai Y

2003-10-01

267

Exact solution of multilayered piezoelectric diaphragms.  

Science.gov (United States)

This paper investigates dynamic behavior of multilayered piezoelectric diaphragms that are simplified as laminated plates. The validity of the dynamic analysis based on the simplified clamped multilayered plate model has first been studied using ANSYS finite element (FE)-codes. The simplified, clamped, multilayered plate model has been verified to be a reasonable one in comparison with the exact model. Subsequently, the frequency characteristics of clamped rectangular piezoelectric laminated plates were further analytically investigated. Using the classical laminated plate theory, mechanical, electrical, and electromechanical characteristics of the multilayered piezoelectric diaphragms were studied. For ease of calculation, the dimensionless method was adopted. Furthermore, numerical analysis was carried out using the Rayleigh-Ritz method. Influence of dimensions of the laminar diaphragm on nature frequencies also was studied. The thickness ratio of the PZT layer to the total thickness of the laminar diaphragm has been optimized to obtain the largest deflection. PMID:14609065

Yao, Linquan; Lu, Li; Wang, Zhihong; Zhu, Weiguang; Dai, Ying

2003-10-01

268

Interactions in bonded soft magnetic particle multilayers  

International Nuclear Information System (INIS)

Magnetisation measurements have been made on a polymer-bonded NiFe/CoFe multilayered structure. Changes in the magnetisation loop in relation to the direction of the applied field have been attributed to associated demagnetisation factors. Computation has also been performed, using a finite element package to calculate the levels of induction within the multilayered sample, as a function of magnitude and orientation of the applied field.

2003-08-01

269

Multichannel bandpass filters utilizing multilayer photonic crystal.  

UK PubMed Central (United Kingdom)

We demonstrate multichannel optical bandpass filters utilizing alternating dielectric multilayers stacked on a patterned substrate. A microstructured Si/SiO(2) multilayer was formed by rf biased magnetron sputtering process on a fused silica substrate with surface gratings. The bandwidths of each filter channel were measured to be 50~175 nm in the near infrared region. Control of center wavelength and bandwidth by the grating pitch was verified.

Ohtera Y; Yamada H

2013-04-01

270

Fretting wear of metallic multilayer films  

International Nuclear Information System (INIS)

[en] Fretting wear behaviour of electrodeposited Cu/Ni multilayer films with 10 and 5 nm thick sublayers has been investigated against a hardened steel ball as the counter body and compared with that of the constituents, Cu and Ni. The wear tests were carried out by using a ball-on-flat geometry at a translation frequency of 8 Hz and slip amplitude of 100 ?m. Friction force was recorded on line during the tests. At the end of the tests, the wear scars were examined by laser surface profilometry, scanning electron microscopy and energy dispersive X-ray microanalysis. It has been observed that the frictional and wear mechanisms are very different for copper, nickel and Cu/Ni multilayers. Fretting of copper creates a relatively smooth wear scar mainly by mechanical ploughing of the asperities on steel counterbody (abrasive wear) and shows a very little third body interaction. Fretting of nickel involves adhesive wear resulting in a large transfer of steel to nickel, which is attributed to the strong chemical interaction between nickel and the steel counterbody. Fretting on multilayers involves a strong third body interaction resulting in ploughing mainly by debris (abrasive wear). The coefficient of friction is approximately 0.45 for copper, and approximately 0.8 for nickel as well as for multilayers. The values of the coefficient of friction for nickel and Cu/Ni multilayers found under the present fretting conditions are approximately double the corresponding values reported earlier for sliding wear conditions. It has been found that Cu/Ni multilayer is more resistance to fretting wear than the constituents, copper and nickel. Furthermore, the fretting wear resistance of Cu/Ni multilayers with 5 nm thick sublayer is better than that of the multilayers with 10 nm thick sublayers

2003-11-01

271

Epidemiology of recurrent venous thrombosis  

Scientific Electronic Library Online (English)

Full Text Available Abstract in english Venous thrombosis, including deep vein thrombosis and pulmonary embolism, is a common disease that frequently recurs. Recurrence can be prevented by anticoagulants, but this comes at the risk of bleeding. Therefore, assessment of the risk of recurrence is important to balance the risks and benefits of anticoagulant treatment. This review briefly outlines what is currently known about the epidemiology of recurrent venous thrombosis, and focuses in more detail on potential (more) new risk factors for venous recurrence. The general implications of these findings in patient management are discussed.

Ribeiro, D.D.; Lijfering, W.M.; Barreto, S.M.; Rosendaal, F.R.; Rezende, S.M.

2012-01-01

272

Epidemiology of recurrent venous thrombosis.  

UK PubMed Central (United Kingdom)

Venous thrombosis, including deep vein thrombosis and pulmonary embolism, is a common disease that frequently recurs. Recurrence can be prevented by anticoagulants, but this comes at the risk of bleeding. Therefore, assessment of the risk of recurrence is important to balance the risks and benefits of anticoagulant treatment. This review briefly outlines what is currently known about the epidemiology of recurrent venous thrombosis, and focuses in more detail on potential new risk factors for venous recurrence. The general implications of these findings in patient management are discussed.

Ribeiro DD; Lijfering WM; Barreto SM; Rosendaal FR; Rezende SM

2012-01-01

273

Laterally graded multilayer double-monochromator  

International Nuclear Information System (INIS)

The authors describe a tunable multilayer monochromator with an adjustable bandpass to be used for reflectivity and grazing incidence diffraction studies on surfaces at energies near 10 keV. Multilayers have a bandpass typically 100 times larger than the Si(111) reflection, and by using multilayers an experimenter can significantly increase data collection rates over those available with a Si monochromator. The transmission through 1 and 2 laterally graded multilayer (LGML) reflections was recorded versus photon energy. The identical LGMLs were comprised of 60 bilayers of W and C on 100 x 25 x 3 mm float glass with a bilayer spacing varying from 35 to 60 angstrom. The average gradient was 0.27 angstrom/mm along the long dimension. The rms deviation of the data for the bilayer spacing from a linear fit was 0.36 angstrom. Data were obtained for a nondispersive (±) double-multilayer arrangement. The relative bandpass width (FWHM) when the two multilayers exposed the same bilayer spacing was measured to be 2.2% with a transmission of 78.7 ± 1.6%. This value is consistent with the transmission of 88.9% that they also measured for a single LGML at HASYLAB beamline D4. The bandpass was tunable in the range 1.1% to 2.2%.

1999-01-01

274

Laterally graded multilayer double-monochromator.  

Energy Technology Data Exchange (ETDEWEB)

The authors describe a tunable multilayer monochromator with an adjustable bandpass to be used for reflectivity and grazing incidence diffraction studies on surfaces at energies near 10 keV. Multilayers have a bandpass typically 100 times larger than the Si(111) reflection, and by using multilayers an experimenter can significantly increase data collection rates over those available with a Si monochromator. The transmission through 1 and 2 laterally graded multilayer (LGML) reflections was recorded versus photon energy. The identical LGMLs were comprised of 60 bilayers of W and C on 100 x 25 x 3 mm float glass with a bilayer spacing varying from 35 to 60 {angstrom}. The average gradient was 0.27 {angstrom}/mm along the long dimension. The rms deviation of the data for the bilayer spacing from a linear fit was 0.36 {angstrom}. Data were obtained for a nondispersive ({+-}) double-multilayer arrangement. The relative bandpass width (FWHM) when the two multilayers exposed the same bilayer spacing was measured to be 2.2% with a transmission of 78.7 {+-} 1.6%. This value is consistent with the transmission of 88.9% that they also measured for a single LGML at HASYLAB beamline D4. The bandpass was tunable in the range 1.1% to 2.2%.

Als-Nielsen, J.; Erdmann, J.; Gaarde, P.; Krasnicki, S.; Liu, C.; Macrander, A. T.; Maj, J.; Mancini, D.

1999-09-01

275

Protein secondary structure prediction using modular reciprocal bidirectional recurrent neural networks.  

Science.gov (United States)

The supervised learning of recurrent neural networks well-suited for prediction of protein secondary structures from the underlying amino acids sequence is studied. Modular reciprocal recurrent neural networks (MRR-NN) are proposed to model the strong correlations between adjacent secondary structure elements. Besides, a multilayer bidirectional recurrent neural network (MBR-NN) is introduced to capture the long-range intramolecular interactions between amino acids in formation of the secondary structure. The final modular prediction system is devised based on the interactive integration of the MRR-NN and the MBR-NN structures to arbitrarily engage the neighboring effects of the secondary structure types concurrent with memorizing the sequential dependencies of amino acids along the protein chain. The advanced combined network augments the percentage accuracy (Q?) to 79.36% and boosts the segment overlap (SOV) up to 70.09% when tested on the PSIPRED dataset in three-fold cross-validation. PMID:20472322

Babaei, Sepideh; Geranmayeh, Amir; Seyyedsalehi, Seyyed Ali

2010-05-15

276

76 FR 76693 - Multilayered Wood Flooring From the People's Republic of China: Countervailing Duty Order  

Science.gov (United States)

...Administration [C-570-971] Multilayered Wood Flooring From the People's Republic of China...CVD'') order on multilayered wood flooring from the People's Republic of China...producers and exporters of multilayered wood flooring from the PRC. See Multilayered...

2011-12-08

277

[Recurrent left atrial myxoma].  

Science.gov (United States)

Primary cardiac tumors are rare. Mixomas are the most common among them; 75% are located in the left atrium, 20% in the right atrium, and the rest in the ventricles. The seldom appear in atrio-ventricular valves. Recidivant mixoma are also rare, appearing in 1-5% of all patients that have undergone surgical treatment of a mixoma. In this paper we present our experience with a female patient, who 8 years after having been operated of a left atrial mixoma, began with symptoms of mild heart failure. Transthoracic echocardiography revealed recurrence of the tumor, and was therefore subjected to a second open-heart surgery from which she recovered without complications. PMID:14959453

Moreno Martínez, Francisco L; Lagomasino Hidalgo, Alvaro; Mirabal Rodríguez, Roger; López Bermúdez, Félix H; López Bernal, Omaida J

278

Recurrent pneumothoraces in miliary tuberculosis.  

Science.gov (United States)

An 18-year-old female patient with miliary tuberculosis presented with bilateral, simultaneous pneumothoraces, which were recurrent with a bronchopleural fistula. The recurrent pneumothoraces were managed with tube thoracostomy and pleurodesis. Various possible pathogenetic mechanisms of this rare complication are discussed. PMID:3227556

Chandra, K S; Prasad, A S; Prasad, C E; Murthy, K J; Srinivasulu, T

1988-10-01

279

Treatment possibilities of recurrent lymphogranulomatosis  

International Nuclear Information System (INIS)

The authors present seven typical cases chosen from a group of thirty patients with recurrent Hodgkin's disease. One out of these patients suffered from two recurrences, five patients from three recurrences each, and one patient from six recurrences. The observation period, beginning with the primary treatment, was between five and 16 years. None of the patients was exclusively irradiated or only treated by cytostatic drugs. Therefore after primary radiotherapy in the stages I to III A, later recurrences could often be successfully treated by an alternating application of cytostatic drugs and repeated radiotherapy. After primary chemotherapy of the advanced primary stages III B to IV B, too, a remission of the second and third recurrence could often be achieved by radiotherapy. Futhermore, the application of alternative schemes such as Holoxan-Vepesid has to be taken into account in the treatment of recurrences. The repeated application of C-MOPP after an interval of at least twelve months also produces good rates of response. The present results allow to make the conlusion that a successful treatment of the second and third and even of further recurrences is possible by a combined application of irradiation and cytostatic therapy. (orig.).

1984-06-02

280

Treatment possibilities of recurrent lymphogranulomatosis  

Energy Technology Data Exchange (ETDEWEB)

The authors present seven typical cases chosen from a group of thirty patients with recurrent Hodgkin's disease. One out of these patients suffered from two recurrences, five patients from three recurrences each, and one patient from six recurrences. The observation period, beginning with the primary treatment, was between five and 16 years. None of the patients was exclusively irradiated or only treated by cytostatic drugs. Therefore after primary radiotherapy in the stages I to III A, later recurrences could often be successfully treated by an alternating application of cytostatic drugs and repeated radiotherapy. After primary chemotherapy of the advanced primary stages III B to IV B, too, a remission of the second and third recurrence could often be achieved by radiotherapy. Futhermore, the application of alternative schemes such as Holoxan-Vepesid has to be taken into account in the treatment of recurrences. The repeated application of C-MOPP after an interval of at least twelve months also produces good rates of response. The present results allow to make the conlusion that a successful treatment of the second and third and even of further recurrences is possible by a combined application of irradiation and cytostatic therapy.

Scherer, E.; Mueller, R.D.

1985-04-01

 
 
 
 
281

Recurrent Rotor-Router Configurations  

CERN Document Server

We prove the existence of recurrent initial configurations for the rotor walk on many graphs, including Z^d, and planar graphs with locally finite embeddings. We also prove that recurrence and transience of rotor walks are invariant under changes in the starting vertex and finite changes in the initial configuration.

Angel, Omer

2011-01-01

282

Local recurrence of laryngeal carcinoma  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Stoma recurrence following total laryngectomy is one of the most severe complications with extremely poor prognosis. Objective: The aim of our study is to analyze the risk factors for stoma recurrence development and to highlight the measures for prevention.Materials and methods: We preformed retr...

Skerleva, D; Stoyanov, S; Rangachev, J; Assenova, K

283

Recurrent pneumothoraces in miliary tuberculosis.  

UK PubMed Central (United Kingdom)

An 18-year-old female patient with miliary tuberculosis presented with bilateral, simultaneous pneumothoraces, which were recurrent with a bronchopleural fistula. The recurrent pneumothoraces were managed with tube thoracostomy and pleurodesis. Various possible pathogenetic mechanisms of this rare complication are discussed.

Chandra KS; Prasad AS; Prasad CE; Murthy KJ; Srinivasulu T

1988-10-01

284

Genetics Home Reference: Benign recurrent intrahepatic cholestasis  

Science.gov (United States)

... OMIM Genetic disorder catalog Conditions > Benign recurrent intrahepatic cholestasis On this page: Description Genetic changes Inheritance Diagnosis ... Reviewed April 2012 What is benign recurrent intrahepatic cholestasis? Benign recurrent intrahepatic cholestasis (BRIC) is characterized by ...

285

Plastic behavior of Cu/Ni multilayers  

Energy Technology Data Exchange (ETDEWEB)

In order to study the plasticity in Cu-Ni multilayers deposited on single crystals of nanoindentation measurements, and by the transmission of well characterized dislocations from the underlying substrate by tensile deformation of Cu single crystals. Various multilayers were deposited by physical vapor deposition with layer thicknesses varying between 1,000 and 20 Angstroms (for a total thickness between 0.8 and 1 {micro}m). Two types of experiments were designed. The first one aimed at injecting, in a controlled way, some dislocations from the substrate into the multilayers; the second type of experiment concerned the structure of the multilayer surface after having plastically pushed the material away from a nanoindenter. This communication reports the results from the nanoindentation measurements, as well as the observations of slip on the surface. The authors observed through the injection of dislocations by nanoindentation that the multilayers increase in strength with refinement of the layer structure but at thicknesses below 35 {angstrom} exhibits a softening behavior. Also observation of the upheaval around the nanoindent showed an evolution from slip lines to more spread plasticity with refinement of the layer structure.

Verdier, M.; Hawley, M.; Nastasi, M.; Kung, H. [Los Alamos National Lab., NM (United States); Niewczas, M. [McMaster Univ., Hamilton, Ontario (Canada). Dept. of Materials Science and Engineering; Embury, J.D. [Los Alamos National Lab., NM (United States)]|[McMaster Univ., Hamilton, Ontario (Canada). Dept. of Materials Science and Engineering

1998-12-31

286

Cryoablation of recurrent sacrococcygeal tumors.  

UK PubMed Central (United Kingdom)

PURPOSE: To review the safety and efficacy of cryoablation of recurrent sacrococcygeal tumors. MATERIALS AND METHODS: The radiology departmental ablation database was retrospectively searched for cases of cryoablation performed to treat recurrences of sacrococcygeal tumors between January 1, 2010, and August 1, 2011. Patient demographics, procedure technical parameters, and patient outcomes were reviewed. RESULTS: Five cases of recurrent chordoma and one recurrent myxopapillary ependymoma were treated with cryoablation in six patients whose ages ranged from 31 to 80 years. The tumors measured 14-39 mm in maximal dimension. Cryoablation was performed with the use of computed tomography guidance (n = 5) or a combination of ultrasound and magnetic resonance imaging guidance (n = 1). Sterile fluid was instilled to displace adjacent bowel and/or vagina in four cases, and electromyography monitoring was performed in two cases with adjacent nerve roots. Two patients with recurrent chordoma were treated for palliation of pain, with complete pain relief in one patient (pain recurred after 6 wk) and immediate reduction in pain from a score of six to a score of two on a 10-point scale in the other (pain recurred after 7 mo). Four tumors were treated for local control, with no evidence of recurrence on follow-up imaging at 3, 6, 12, and 15 months. No serious complication occurred. CONCLUSIONS: Limited results suggest cryoablation to be a safe and relatively effective means of treating recurrent sacrococcygeal neoplasms for local control or palliation of pain in this small series with short-term follow-up.

Kurup AN; Woodrum DA; Morris JM; Atwell TD; Schmit GD; Welch TJ; Yaszemski MJ; Callstrom MR

2012-08-01

287

Vulvovaginitis Candidiasis Recurrence During Pregnancy  

Directory of Open Access Journals (Sweden)

Full Text Available Vulvovaginitis is the most common gynecologic condition seen by practitioners rendering primary care to women. Vulvovaginitis Candidiasis (VVC) is the most common type of vaginitis and this study aimed at specifying VVC recurrence during pregnancy. In this prospective study, 150 pregnant women suffering from vaginal excretion, morsus and itching were studied. Initially, the patients were treated using clotrimazole local cream (5 g) for 7 successive days. After initial treatment, the patients were freely visited once a month until delivery considering vaginitis symptoms and VVC recurrence was examined during pregnancy. Mean age of the understudy mothers was 27.26±3.76. Mean of recurrence number was 0.17±0.48 during the first trimester. Mean of recurrence number was 0.92±0.76 during the second trimester. Mean of recurrence number was 2.16±0.63 during the third trimester. Statistically significant difference was between recurrences during three trimesters of pregnancy (p<0.001). There is statistically significant difference between mean number of recurrences during three trimesters of pregnancy.

Z. Fardiazar; F. Ronaci; R. Torab; M. Goldust

2012-01-01

288

Chronic recurrent multifocal osteomyelitis.  

UK PubMed Central (United Kingdom)

Chronic recurrent multifocal osteomyelitis (CRMO) is an autoinflammatory bone disease occurring primarily in children and adolescents. Episodes of systemic inflammation occur due to immune dysregulation without autoantibodies, pathogens or antigen-specific T cells. CRMO is characterised by the insidious onset of pain with swelling and tenderness over the affected bones. Clavicular involvement was the classical description; however, the metaphyses and epiphyses of long bones are frequently affected. Lesions may occur in any bone, including vertebrae. Characteristic imaging includes bone oedema, lytic areas, periosteal reaction and soft tissue reaction. Biopsies from affected areas display polymorphonuclear leucocytes with osteoclasts and necrosis in the early stages. Subsequently, lymphocytes and plasma cells predominate followed by fibrosis and signs of reactive new bone forming around the inflammation. Diagnosis is facilitated by the use of STIR MRI scanning, potentially obviating the need for biopsy and unnecessary long-term antibiotics due to incorrect diagnosis. Treatment options include non-steroidal anti-inflammatory drugs and bisphosphonates. Biologics have been tried in resistant cases with promising initial results. Gene identification has not proved easy although research in this area continues. Early descriptions of the disease suggested a benign course; however, longer-term follow up shows that it can cause significant morbidity and longer-term disability. Although it has always been thought of as very rare, the prevalence is likely to be vastly underestimated due to poor recognition of the disease.

Roderick MR; Ramanan AV

2013-01-01

289

Acute recurrent appendicitis with appendicolith.  

UK PubMed Central (United Kingdom)

Appendiceal disease can be acute, acute recurrent, or chronic. Acute appendicitis is the most common form. Acute recurrent appendicitis is more common than chronic appendicitis. In children the clinical manifestations of appendicitis are variable. Patients who have an appendicolith usually develop appendicitis, often with perforation. A case is presented of 3-year follow-up of a patient with an appendicolith and acute recurrent appendicitis. The literature about appendicoliths is reviewed. In the appropriate clinical setting, a history of prior episodes of similar right lower quadrant pain does not preclude the diagnosis of appendiceal disease. Awareness of the less common forms of appendicitis is important so that appropriate treatment is not delayed.

Hollerman JJ; Bernstein MA; Kottamasu SR; Sirr SA

1988-11-01

290

Bragg condition in absorbing x-ray multilayers  

International Nuclear Information System (INIS)

[en] The angle of maximum reflectivity from a multilayer x-ray reflector is influenced by absorption in the medium. Using multilayer theory we show how the full refractive correction compares to the usual correction that includes only the effect of dispersion. The physical significance of the two corrections is discussed. The absorption correction is computed for some multilayer systems of current interest

1982-03-15

291

Interlayer exchange coupling in (Ga,Mn)As based multilayers  

CERN Multimedia

Exhibiting antiferromagnetic interlayer coupling in dilute magnetic semiconductor multilayers is essential for the realisation of magnetoresistances analogous to giant magnetoresistance in metallic multilayer structures. In this work we use a mean-field theory of carrier induced ferromagnetism to explore possible (Ga,Mn)As based multilayer structures that might yield antiferromagnetic coupling.

Giddings, A D; Gallagher, B L

2006-01-01

292

New Si-based multilayers for solar cell applications  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In this article, we have fabricated and studied a new multilayer structure Si-SiO2/SiNx by reactive magnetron sputtering. The comparison between SiO2 and SiNx host matrices in the optical properties of the multilayers is detailed. Structural analysis was made on the multilayer structures using Fouri...

Nalini, R Pratibha; Dufour, Christian; Cardin, Julien; Gourbilleau, Fabrice

293

Multilayer mirrors and beam splitters for soft X-rays  

Science.gov (United States)

X-ray transmission coefficients for perfect multilayers have been derived based upon the optics of thin films at large angles of incidence. The new transmission coefficient together with the previously given diffraction coefficient can now be used to characterize the optical properties of multilayers. Applications of flat multilayer as X-ray beam splitters, polarizers and normal incidence mirrors are also presented.

Lee, P.

1982-10-01

294

Magnetic studies of Fe/Cu multilayers  

International Nuclear Information System (INIS)

The structural and magnetic properties of sputtered Fe/Cu multilayers are examined as a function of Fe layer thickness tFe by means of X-ray diffraction, Moessbauer spectrometry and superconducting quantum interference magnetometer. The temperature dependence of the spontaneous magnetization M(T) is well described by a T3/2 law in all multilayers in the temperature range 5-300 K. The interface anisotropy constant of Fe/Cu multilayers, Ks, is found to be 0.31 and 0.45 erg/cm2 at 5 and 300 K, respectively. A spin-wave theory has been used to explain the temperature dependence of the magnetization and the approximate values for the bulk exchange interaction Jb, surface exchange interaction Js and the interlayer coupling strength JI for various Fe layer thicknesses have been obtained.

2008-07-01

295

Magnetic studies of Fe/Cu multilayers  

Energy Technology Data Exchange (ETDEWEB)

The structural and magnetic properties of sputtered Fe/Cu multilayers are examined as a function of Fe layer thickness t{sub Fe} by means of X-ray diffraction, Moessbauer spectrometry and superconducting quantum interference magnetometer. The temperature dependence of the spontaneous magnetization M(T) is well described by a T{sup 3/2} law in all multilayers in the temperature range 5-300 K. The interface anisotropy constant of Fe/Cu multilayers, K{sub s}, is found to be 0.31 and 0.45 erg/cm{sup 2} at 5 and 300 K, respectively. A spin-wave theory has been used to explain the temperature dependence of the magnetization and the approximate values for the bulk exchange interaction J{sub b}, surface exchange interaction J{sub s} and the interlayer coupling strength J{sub I} for various Fe layer thicknesses have been obtained.

El Khiraoui, S. [Laboratoire de Physique et Mecanique des Materiaux, Universite Sultan Moulay Slimane, FST de Beni-Mellal, B.P. 523, 23000 Beni-Mellal (Morocco); Sajieddine, M. [Laboratoire de Physique et Mecanique des Materiaux, Universite Sultan Moulay Slimane, FST de Beni-Mellal, B.P. 523, 23000 Beni-Mellal (Morocco)], E-mail: sajieddinem@yahoo.fr; Hehn, M.; Robert, S.; Lenoble, O.; Bellouard, C. [Laboratoire de Physique des Materiaux, UMR-CNRS 7556, B.P. 239, 54506 Vandoeuvre-les-Nancy Cedex (France); Sahlaoui, M. [Laboratoire de Physique et Mecanique des Materiaux, Universite Sultan Moulay Slimane, FST de Beni-Mellal, B.P. 523, 23000 Beni-Mellal (Morocco); Benkirane, K. [Laboratoire des Materiaux, Micro-electronique, Automatique et Thermique, Faculte des Sciences Ain-Chock, Universite Hassan II, B.P. 5366 Maarif, Casablanca (Morocco)

2008-07-01

296

Magnetic properties of Ni/Pt multilayers  

Energy Technology Data Exchange (ETDEWEB)

We have grown Ni/Pt multilayers with Pt buffer layer, by evaporation under UHV conditions on glass substrates maintained at 300 K. The magnetic properties of Ni/Pt multilayers are examined as a function of Ni layer thickness t {sub Ni}. The temperature dependence of the spontaneous magnetization M(T) is well described by a T {sup 3/2} law in all multilayers. A spin-wave theory has been used to explain the temperature dependence of the magnetization and the approximate values for the bulk exchange interaction J {sub b}, surface exchange interaction J {sub S} and the interlayer coupling strength J {sub I} for various Ni layer thicknesses have been obtained.

Benkirane, K. [Laboratoire de Traitement d' information, Faculte des Sciences Ben' Msik Sidi-Othmane, B.P. 7955, Sidi-Othmane, Casablanca (Morocco)]. E-mail: karbenkirane@yahoo.fr; Elkabil, R. [Laboratoire de Traitement d' information, Faculte des Sciences Ben' Msik Sidi-Othmane, B.P. 7955, Sidi-Othmane, Casablanca (Morocco); Lassri, M. [Laboratoire de Physique des Materiaux et de Micro-electronique, Faculte des Sciences Ain Chock, Universite Hassan II, B.P. 5366 Ma-hat arif, Route d' El Jadida, km-8, Casablanca, Marocco (Morocco); Abid, M. [Laboratoire de Physique des Materiaux et de Micro-electronique, Faculte des Sciences Ain Chock, Universite Hassan II, B.P. 5366 Ma-hat arif, Route d' El Jadida, km-8, Casablanca, Marocco (Morocco); Lassri, H. [Laboratoire de Physique des Materiaux et de Micro-electronique, Faculte des Sciences Ain Chock, Universite Hassan II, B.P. 5366 Ma-hat arif, Route d' El Jadida, km-8, Casablanca, Marocco (Morocco); Berrada, A. [Laboratoire de Physique des Materiaux, Faculte des Sciences, Avenue Ibn Batouta, B.P. 1014, Rabat (Morocco); Hamdoun, A. [Laboratoire de Traitement d' information, Faculte des Sciences Ben' Msik Sidi-Othmane, B.P. 7955, Sidi-Othmane, Casablanca (Morocco); Krishnan, R. [Laboratoire de Magnetisme et d' Optique, URA 1531, 45 Avenue des Etats Unis, 78035 Versailles Cedex (France)

2005-01-15

297

Localized modes in defective multilayer structures  

CERN Document Server

In this paper, the localized surface modes in a defective multilayer structure has been investigated. It is shown that the defective multilayer structures can support two different kind of localized modes depending on the position and the thickness of the defect layer. One of these modes is localized at the interface between the multilayer structure and a homogeneous medium (the so-called surface mode) and the other one is localized at the defect layer (defect localized mode). We reveal that the presence of defect layer pushes the dispersion curve of surface modes to the lower or the upper edge of the photonic bandgap depending on the homogeneous medium is a left-handed or right-handed medium (e.g. vacuum), respectively. So, the existence region of the surface modes restricted. Moreover, the effect of defect on the energy flow velocity of the surface modes is discussed.

Entezar, S Roshan

2009-01-01

298

Localized modes in defective multilayer structures  

International Nuclear Information System (INIS)

In this paper, we investigate the localized surface modes in a defective multilayer structure. We show that the defective multilayer structure can support two different kinds of localized modes, depending on the position and the thickness of the defect layer. In one kind, the modes are localized at the interface between the multilayer structure and a homogeneous medium (the so-called surface modes). While, in the other one, the modes are localized at the defect layer (defect-localized modes). We reveal that in the presence of the defect layer, the dispersion curve of the surface modes are pushed to the lower (upper) edge of the photonic band gap when the homogeneous medium is a left-handed (right-handed) material. Therefore, the existence regions of the surface modes are restricted due to the defect layer. Moreover, the effect of defect on the energy flow velocity of the surface modes is discussed.

2009-01-01

299

Multilayers for high heat load synchrotron applications  

Science.gov (United States)

Multilayers are the optical elements of choice in any situation where flux rather than resolution is desired. They can be tailored to optimize either reflectivity at fixed or variable energy, or heat resistance, or bandpass, or harmonic rejection. The present state of the art of x-ray multilayers is presented, and the possible applications are reviewed, including the use of multilayers as soft x-ray polarizers, large-passband elements for hard x rays, and power filters. In the situation of very intense beams the increase of temperature can produce significant changes of reflectivity, which have been extensively studied at the microstructure level in some cases, such as W/C, W/Si, and Mo/Si. Existing and prospective solutions are detailed, including heat treatment prior to x-ray exposure, use of compound materials, efficient cooling, and modification of the electric field distribution by nonperiodic arrangements.

Ziegler, Eric

1995-02-01

300

Yield Stress and Scaling of Polyelectrolyte Multilayer Modified Suspensions: Effect of Polyelectrolyte Conformation during Multilayer Assembly.  

UK PubMed Central (United Kingdom)

The yield stress of polyelectrolyte multilayer modified suspensions exhibits a surprising dependence on the polyelectrolyte conformation of multilayer films. The rheological data scale onto a universal master curve for each polyelectrolyte conformation as the particle volume fraction, ?, and the ionic strength of the background fluid, I, are varied. It is shown that rough films with highly coiled, brushy polyelectrolytes significantly enhance the yield stress. Moreover, via the ionic strength I of the background fluid, the dynamic yield stress of brushy polyelectrolyte multilayers can be finely adjusted over 2 decades.

Hess A; Aksel N

2013-09-01

 
 
 
 
301

Yield stress and scaling of polyelectrolyte multilayer modified suspensions: effect of polyelectrolyte conformation during multilayer assembly.  

UK PubMed Central (United Kingdom)

The yield stress of polyelectrolyte multilayer modified suspensions exhibits a surprising dependence on the polyelectrolyte conformation of multilayer films. The rheological data scale onto a universal master curve for each polyelectrolyte conformation as the particle volume fraction, phi, and the ionic strength of the background fluid, I, are varied. It is shown that rough films with highly coiled, brushy polyelectrolytes significantly enhance the yield stress. Moreover, via the ionic strength I of the background fluid, the dynamic yield stress of brushy polyelectrolyte multilayers can be finely adjusted over 2 decades.

Hess A; Aksel N

2013-08-01

302

Internal stresses and strains in coherent multilayers  

Energy Technology Data Exchange (ETDEWEB)

Formulae are given for the strain and stress tensors in a periodic multilayer which may contain any number of layers, each with a different lattice parameter, different elastic constants and different thickness. The layers are assumed to be parallel sided, elastically isotropic and to have a thickness much smaller than the dimensions in the plane of the layers. The results are applied to metal and semiconductor heterostructures which contain equi-biaxial tensions and compressions and to lamellar Ti-Al in which there are additional in-plane shears. A preliminary discussion is given of the loss of coherency in a multilayer with layers of different thicknesses.

Shoykhet, B. [Wright Lab., Wright-Patterson AFB, OH (United States). Materials Directorate]|[Reliance Electric Co., Cleveland, OH (United States); Grinfeld, M.A. [Wright Lab., Wright-Patterson AFB, OH (United States). Materials Directorate]|[Educational Testing Service, Princeton, NJ (United States); Hazzledine, P.M. [Wright Lab., Wright-Patterson AFB, OH (United States). Materials Directorate]|[UES Inc., Dayton, OH (United States)

1998-07-01

303

Exchange interactions in Fe/Y multilayers  

International Nuclear Information System (INIS)

The magnetization of Fe/Y multilayers has been measured as a function of temperature. A bulk-like T 3/2 temperature dependence of the magnetization is observed for all multilayers in the temperature range 5-300 K. The spin-wave constant B is found to decrease inversely with t Fe. A simple theoretical model with exchange interactions only, and with non-interacting magnons, has been used to explain the temperature dependence of the magnetization and the approximate values for the bulk exchange interaction J b, surface exchange interaction J s and the interlayer exchange interaction J I for various Fe layer thicknesses have been obtained.

2005-05-17

304

Magnetoresistance of alloy films and multilayers  

Energy Technology Data Exchange (ETDEWEB)

The anisotropic magnetoresistance effect of alloy films and so-called giant magnetoresistance of superlattice multilayer films are reviewed. The usefulness for phenomenological explanation of both the anisotropic magnetoresistance and giant magnetoresistance of the two-current model, suggested first by Motto and subsequently extended by several researchers, is stressed. The relationship between the magnetoresistance and the magnetic anisotropy field is demonstrated for films exhibiting either anisotropic magnetoresistance or giant magnetoresistance. The magnetoresistances of multilayer films both with and without magnetic interaction between adjacent layers are compared. The dependence of the magnetoresistance on temperature is briefly discussed.

Miyazaki, T. (Tohoku Univ., Sendai (Japan))

1993-05-01

305

Multilayered Piezoelectric Transformers for Small Power Supplies  

Science.gov (United States)

In this paper, new piezoelectric transformers for AC-DC converters and DC-DC converters are presented. These piezoelectric transformers operate in a higher vibration mode. They were designed to be multilayered in the thickness direction to achieve high-power operation. First, we performed the simulation for designing a transformer using finite element method (FEM) analysis, and calculated its size using Vin=100 V, Vout=10 V, Pout=20 W, and an efficiency ? of more than 90%. Second, we simulated some electrode patterns of a multilayered piezoelectric transformer. We investigated experimentally the transformers manufactured using the simulation results, and the highest efficiency of 93.7% was obtained.

Endow, Tsutomu; Hirose, Seiji

2003-09-01

306

Multilayer technology for diffractive optical elements.  

Science.gov (United States)

The proposed multilayer technology makes it possible to approximate a continuous phase distribution by discrete phase steps. Compared with binary techniques, a higher diffraction efficiency can be achieved. In most known processes a bulk substrate is used and etched directly; therefore it is difficult to control the height of the phase steps. We propose applying layers of a well-known thickness and structuring them with a selective etching process. In this new multilayer process for reflecting elements a system of metal and dielectric layers is used that can easily be produced by standard methods. PMID:21102864

Goebel, B; Wang, L L; Tschudi, T

1996-08-01

307

Multilayer technology for diffractive optical elements.  

UK PubMed Central (United Kingdom)

The proposed multilayer technology makes it possible to approximate a continuous phase distribution by discrete phase steps. Compared with binary techniques, a higher diffraction efficiency can be achieved. In most known processes a bulk substrate is used and etched directly; therefore it is difficult to control the height of the phase steps. We propose applying layers of a well-known thickness and structuring them with a selective etching process. In this new multilayer process for reflecting elements a system of metal and dielectric layers is used that can easily be produced by standard methods.

Goebel B; Wang LL; Tschudi T

1996-08-01

308

YBCO based multilayers for optoelectronic devices  

International Nuclear Information System (INIS)

YBCO based multilayers have been deposited independently by three techniques: laser ablation, inverted cylindrical target sputtering (ICM) and on-axis planar D.C. Magnetron Sputtering. The last technique is used to cover uniformly R-plane sapphire and LaAlO3 2 inch wafers with YBCO or multilayers to achieve optoelectronic devices such as infrared detectors. Very thin (- 3 nm) YSZ and MgO dielectric films have been studied as tunnel barriers for making such high Tc tunnel junctions. 14 refs., 11 figs.

1991-01-01

309

Recurrent ameloblastoma of the mandible  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Ameloblastoma is an agressive locally recurring neoplasm of odentogenic epithelium. Here we describe a case of mandibular ameloblastoma with 12 yrs. history of local recurrences followed with history of excision twice (10 yrs. and 7 years back).

Joshi, C. P.; Vyas, K. C.; Deedwania, Seema; Jain, Sanjeev; Mangal, M. M.

310

Recovery After Stroke: Recurrent Stroke  

Science.gov (United States)

Recovery After Stroke: Recurrent Stroke After stroke, survivors tend to focus on rehabilitation and recovery. But, preventing ... your doctor, “Where am I on my stroke recovery journey?” Note: This fact sheet is compiled from ...

311

Management of Recurrent Cervical Cancer.  

Directory of Open Access Journals (Sweden)

Full Text Available Approximately 30% of cervical cancer patients will ultimately fail after definitive treatment.The reported 5-year survival rates of patients with treatment failure are between 3.2%and 13%. Management of recurrences depends on the extent of disease, primary treatment,and performance status/comorbidity. Primary treatment, relapse pattern, and characteristicsat presentation are determinants for prognosis after recurrence. Concurrent chemoradiationachieves significantly better outcome than radiation alone in patients with recurrences afterprimary radical hysterectomy. Isolated paraaortic lymph node metastasis and local recurrenceconfined to cervix were associated with better outcome in failure after definitive radiotherapy.When definitive radiotherapy or surgery plus adjuvant radiotherapy has failed,pelvic exenteration is usually necessary for those had central relapse with clear pelvic sidewalland free of distant metastasis. Radical hysterectomy with or without pelvic node dissectionis considered feasible for small uterine and/or vaginal recurrences with high operativemorbidity. For patients who have recurrences involving the irradiated pelvic wall, pelvicexenteration is usually not an option for curative intent. Intraoperative radiotherapy, combinedoperative radiotherapeutic treatment, and laterally extended endopelvic resection havebeen used in such situations with some success. Chemotherapy alone is basically palliative.Generally, combination chemotherapy could attain higher response rates with no significantimprovement in overall survival than cisplatin alone. Recent investigations indicated benefitsof positron emission tomography in more accurate restaging of recurrent disease. Theimpact of various post-treatment surveillance strategies to early detect treatment failureremains to be evaluated.

Chyong-Huey Lai

2004-01-01

312

MULTILAYER COATING COMPOSITIONS, COATED SUBSTRATES AND METHODS THEREOF  

UK PubMed Central (United Kingdom)

The present invention provides, among other things, multilayer film coating compositions, coated substrates and methods thereof In some embodiments, a structure, comprising a substrate and a multilayer film on the substrate, wherein the multilayer film comprises a first plurality of first units, each first unit comprising a protamine polypeptide. In some embodiments, a structure comprising a microneedle substrate and a multilayer film coated on at least portion of the microneedle substrate, wherein the multilayer film comprises an agent for release and a first plurality of first unit each first unit comprising a first layer and a second layer, wherein the first layer and the second layer are associated with one another.

DEMUTH PETER C; IRVINE DARRELL J; SAMUEL RAYMOND E; HAMMOND PAULA T

313

Piezoelectric multilayer actuator life test.  

UK PubMed Central (United Kingdom)

Potential NASA optical missions such as the Space Interferometer Mission require actuators for precision positioning to accuracies of the order of nanometers. Commercially available multilayer piezoelectric stack actuators are being considered for driving these precision mirror positioning mechanisms. These mechanisms have potential mission operational requirements that exceed 5 years for one mission life. To test the feasibility of using these commercial actuators for these applications and to determine their reliability and the redundancy requirements, a life test study was undertaken. The nominal actuator requirements for the most critical actuators on the Space Interferometry Mission (SIM) in terms of number of cycles was estimated from the Modulation Optics Mechanism (MOM) and Pathlength control Optics Mechanism (POM) and these requirements were used to define the study. At a nominal drive frequency of 250 Hz, one mission life is calculated to be 40 billion cycles. In this study, a set of commercial PZT stacks configured in a potential flight actuator configuration (pre-stressed to 18 MPa and bonded in flexures) were tested for up to 100 billion cycles. Each test flexure allowed for two sets of primary and redundant stacks to be mechanically connected in series. The tests were controlled using an automated software control and data acquisition system that set up the test parameters and monitored the waveform of the stack electrical current and voltage. The samples were driven between 0 and 20 V at 2000 Hz to accelerate the life test and mimic the voltage amplitude that is expected to be applied to the stacks during operation. During the life test, 10 primary stacks were driven and 10 redundant stacks, mechanically in series with the driven stacks, were open-circuited. The stroke determined from a strain gauge, the temperature and humidity in the chamber, and the temperature of each individual stack were recorded. Other properties of the stacks, including the displacement from a capacitance gap sensor and impedance spectra were measured at specific intervals. The average degradation in the stroke over the life test was found to be small (<3%) for the primary stacks and <4% for the redundant stacks. It was noted that about half of the stroke reduction occurred within the first 10 billion cycles. At the end of the life test, it was found that the actuator could recover about half of the lost stroke by applying a dc voltage of 100 V at room temperature. The data up to 100 billion cycles for these tests and the analysis of the experimental results are presented in this paper.

Sherrit S; Bao X; Jones CM; Aldrich JB; Blodget CJ; Moore JD; Carson JW; Goullioud R

2011-04-01

314

A Recurrent Neural Network Approach to Rear Vehicle Detection Which Considered State Dependency  

Directory of Open Access Journals (Sweden)

Full Text Available Experimental vision-based detection often fails in cases when the acquired image quality is reduced by changing optical environments. In addition, the shape of vehicles in images that are taken from vision sensors change due to approaches by vehicle. Vehicle detection methods are required to perform successfully under these conditions. However, the conventional methods do not consider especially in rapidly varying by brightness conditions. We suggest a new detection method that compensates for those conditions in monocular vision-based vehicle detection. The suggested method employs a Recurrent Neural Network (RNN), which has been applied for spatiotemporal processing. The RNN is able to respond to consecutive scenes involving the target vehicle and can track the movements of the target by the effect of the past network states. The suggested method has a particularly beneficial effect in environments with sudden, extreme variations such as bright sunlight and shield. Finally, we demonstrate effectiveness by state-dependent of the RNN-based method by comparing its detection results with those of a Multi Layered Perceptron (MLP).

Kayichirou Inagaki; Shozo Sato; Taizo Umezaki

2003-01-01

315

Numerical simulation and experiment on multilayer stagger-split die.  

UK PubMed Central (United Kingdom)

A novel ultra-high pressure device, multilayer stagger-split die, has been constructed based on the principle of "dividing dies before cracking." Multilayer stagger-split die includes an encircling ring and multilayer assemblages, and the mating surfaces of the multilayer assemblages are mutually staggered between adjacent layers. In this paper, we investigated the stressing features of this structure through finite element techniques, and the results were compared with those of the belt type die and single split die. The contrast experiments were also carried out to test the bearing pressure performance of multilayer stagger-split die. It is concluded that the stress distributions are reasonable and the materials are utilized effectively for multilayer stagger-split die. And experiments indicate that the multilayer stagger-split die can bear the greatest pressure.

Liu Z; Li M; Han Q; Yang Y; Wang B; Sui Z

2013-05-01

316

Noise robustness in multilayer neural network  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The training of multilayered neural networks in the presence of different types of noise is studied. We consider the learning of realizable rules in nonoverlapping architectures. Achieving optimal generalization depends on the knowledge of the noise level, however its misestimation may lead to parti...

Copelli, M.; Eichhorn, R.; Kinouchi, O.; Biehl, M.; Simonetti, R.; Riegler, P.; Caticha, N.

317

Diffraction Gratings Based on Multilayer Structures  

International Science & Technology Center (ISTC)

Development of High Efficiency Diffraction Gratings on the Basis of Multilayer Structures for Monochromators and Polychromators of X-Ray Synchrotron Radiation and for Ultra-High Spectral Resolution X-Ray Diagnostics in the 0.1 – 10 Kev Energy Range

318

Coherent multilayer crystals and method of making  

Energy Technology Data Exchange (ETDEWEB)

A new material consisting of a multilayer crystalline structure which is coherent perpendicular to the layers and where each layer is composed of a single crystalline element. The individual layers may vary from 2.ANG. to 100.ANG. or more in thickness.

Schuller, Ivan K. (Woodridge, IL); Falco, Charles M. (Tucson, AZ)

1984-01-01

319

Coherent multilayer crystals and method of making  

Energy Technology Data Exchange (ETDEWEB)

A new material consisting of a multilayer crystalline structure which is coherent perpendicular to the layers and where each layer is composed of a single crystalline element. The individual layers may vary from 2A to 100A or more in thickness.

Schuller, I.K.; Falco, C.M.

1984-05-15

320

Magnetism and Structure in Metallic Multilayers  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The interplay between magnetism and structure has been studied in magnetic multilayers by electronic structure calculations based on density functional theory and analyzed in terms of models. The main ideas behind the Korringa-Kohn-Rostocker Green’s function method are described and the implement...

Holmström, Erik

 
 
 
 
321

Structural and magnetic aspects of multilayer interfaces  

International Nuclear Information System (INIS)

We show that it is possible to obtain quantitative information about the interface quality by considering the magnetic moments of Fe/V multilayers. We derive a parameter space describing the quality of interfaces and argue that most of the experimentally grown samples lie within a smaller segment of this space.

2003-08-01

322

Structural and magnetic aspects of multilayer interfaces  

Energy Technology Data Exchange (ETDEWEB)

We show that it is possible to obtain quantitative information about the interface quality by considering the magnetic moments of Fe/V multilayers. We derive a parameter space describing the quality of interfaces and argue that most of the experimentally grown samples lie within a smaller segment of this space.

Holmstroem, Erik E-mail: erik.holmstrom@fysik.uu.se; Bergqvist, L.; Skubic, B.; Eriksson, O

2004-05-01

323

Interlayer Coupling in Magnetic/Pd Multilayers  

CERN Document Server

The Anderson model of local-state conduction electron mixing is applied to the p roblem of interlayer magnetic coupling in metallic multilayered structures with palladium (Pd) spacer layers. An oscillation period of $5$ spacer monolayers and the tendency towards ferromag netic bias of the interlayer magnetic coupling that we obtain are consistent with the experimental data.

Shi, Z P; Shi, Zhu-Pei; Klein, Barry M.

1995-01-01

324

Interventions for recurrent corneal erosions.  

UK PubMed Central (United Kingdom)

BACKGROUND: Recurrent corneal erosion is a common cause of disabling ocular symptoms and predisposes the cornea to infection. It may follow corneal trauma. Measures to prevent the development of recurrent corneal erosion following corneal trauma have not been firmly established. Once recurrent corneal erosion develops simple medical therapy (standard treatment) may lead to resolution of the episode. However, some patients continue to suffer when such therapy fails and once resolved further episodes of recurrent erosion may occur. A number of treatment and prophylactic options are then available but there is no agreement as to the best option. OBJECTIVES: To assess the effectiveness and safety of prophylactic and treatment regimens for recurrent corneal erosion. SEARCH METHODS: We searched CENTRAL (which contains the Cochrane Eyes and Vision Group Trials Register) (The Cochrane Library 2012, Issue 6), MEDLINE (January 1946 to June 2012), EMBASE (January 1980 to June 2012), Latin American and Caribbean Literature on Health Sciences (LILACS) (January 1982 to June 2012), the metaRegister of Controlled Trials (mRCT) (www.controlled-trials.com), ClinicalTrials.gov (www.clinicaltrials.gov) and the WHO International Clinical Trials Registry Platform (ICTRP) (www.who.int/ictrp/search/en). We did not use any date or language restrictions in the electronic searches for trials. We last searched the electronic databases on 13 June 2012. We also contacted researchers in the field. SELECTION CRITERIA: We included randomised and quasi-randomised trials that compared a prophylactic or treatment regimen with another prophylaxis/treatment or no prophylaxis/treatment for patients with recurrent corneal erosion. DATA COLLECTION AND ANALYSIS: Two authors independently extracted data and assessed trial quality. We contacted study authors for additional information. MAIN RESULTS: Seven randomised and one quasi-randomised controlled trial were included in the review. The trials were heterogenous and of poor quality. Safety data presented were incomplete. For the treatment of recurrent corneal erosion, a single-centre trial in the UK with 30 participants showed that oral tetracycline 250 mg twice daily for 12 weeks or topical prednisolone 0.5% four times daily for one week, or both, in addition to standard treatment, accelerated healing rates and improved symptoms. A single-centre trial in Sweden with 56 participants showed that excimer laser ablation in addition to mechanical debridement may reduce the number of erosions and improve symptoms. Furthermore, in a single-centre trial in Germany with 100 participants, transepithelial technique for excimer laser ablation had the same efficacy as the traditional subepithelial excimer laser technique but caused less pain. In a small study of 24 participants in UK, therapeutic contact lens wear was inferior to lubricant drops and ointment in abolishing the symptoms of recurrent corneal erosion and had a high complication rate, although the contact lenses used were the older generation with low oxygen permeability. A recent study in Hong Kong with 48 participants found diamond burr polishing to reduce episodes of recurrent corneal erosion. For prophylaxis of further episodes of recurrent corneal erosion, there was no difference in the occurrence of objective signs of recurrent erosion between hypertonic saline ointment versus tetracycline ointment or lubricating ointment in a small Japanese study with 26 participants. Also, in a single-centre study in the UK with 117 participants, there was no difference in symptom improvement between hypertonic saline versus paraffin ointment when used for prophylaxis. In a UK study with 42 participants, lubricating ointment at night in addition to standard treatment to prevent recurrence following traumatic corneal abrasion (erosion) caused by fingernail injury led to increased symptoms of recurrent corneal erosion compared to standard therapy alone. AUTHORS' CONCLUSIONS: Well-designed, masked, randomised controlled trials using standardised methods are needed to establ

Watson SL; Lee MH; Barker NH

2012-01-01

325

Recurrence Statistics of Great Earthquakes  

CERN Multimedia

We investigate the sequence of great earthquakes over the past century. To examine whether the earthquake record includes temporal clustering, we identify aftershocks and remove those from the record. We focus on the recurrence time, defined as the time between two consecutive earthquakes. We study the variance in the recurrence time and the maximal recurrence time. Using these quantities, we compare the earthquake record with sequences of random events, generated by numerical simulations, while systematically varying the minimal earthquake magnitude Mmin. Our analysis shows that the earthquake record is consistent with a random process for magnitude thresholds 7.0<=Mmin<=8.3, where the number of events is larger. Interestingly, the earthquake record deviates from a random process at magnitude threshold 8.4<=Mmin<= 8.5, where the number of events is smaller; however, this deviation is not strong enough to conclude that great earthquakes are clustered. Overall, the findings are robust both qualitat...

Ben-Naim, E; Johnson, P A

2013-01-01

326

Pigmented villonodular synovitis: extrasynovial recurrence.  

Science.gov (United States)

A 32-year-old female athlete underwent arthroscopy for a second recurrence of pigmented villonodular synovitis (PVNS), which was extrasynovial, seen on magnetic resonance imaging. It was noted on arthroscopy that (1) the nodules moved medially with joint insufflation, (2) the nodules were less prominent than on magnetic resonance imaging, and (3) more than 95% of the recurrent tumor was hidden by neosynovium. We believe that the extrasynovial location is because of the more rapid proliferation of the neosynovium relative to the growth of the remaining tumor cells after the previous resection. In resecting pigmented villonodular synovitis with a high risk of recurrence, a layer of periarticular fat should be removed and the surgeon should be wary of change in position with insufflation. PMID:21889289

Jobe, Christopher M; Raza, Anwar; Zuckerman, Lee

2011-09-01

327

Retreatment of recurrent nasopharyngeal carcinoma  

Energy Technology Data Exchange (ETDEWEB)

Thirty patients with recurrent primary nasopharyngeal carcinoma were reirradiated between 1949 and 1976. Twenty eventually demonstrated recurrence at or near the primary site, involving the nasopharynx in 4 and the central nervous system in 16. Long-term palliation was often achieved, and there were no severe complications except for one patient who died of necrosis of the base of the skull. The most frequent problems were hearing loss and trismus; necrosis of the nasopharynx was seen in only 2 patients. With therapy in the range of 18-25 MeV, significant palliation and an occational cure can be achieved without excessive risk. Recurrent disease involving the skull may be controlled for several years using current techniques.

McNeese, M.D.; Fletcher, G.H.

1981-01-01

328

Extreme ultraviolet reflective multilayers at 30.4nm  

Science.gov (United States)

Mutilayers are important optical elements and widely used for extreme ultraviolet astronomical observation. For selecting the emission line multilayers should have high reflectivity and narrow spectral bandwidth. In this paper, six different multilayers including Si/C, Si/B4C, Si/Mo/B4C, Si/SiC, Mg/SiC and Mo/Si were designed for normal incidence angle of 5° at He-IIemission line(?=30.4 nm). These multilayers have been fabricated using a direct current magnetron sputtering system. The period of multilayers were measured by X-ray diffractometer(XRD) and the reflectivities were measured on National Synchrotron Radiation Facility in Hefei, China. Then the reflectivities and the spectral bandwidth of these multilayers were compared respectively. It shows that the spectral bandwidth of multilayers of low Z materials is narrower than that of the normal Mo/Si multiayer, the reflectivity of Si/Mo/B4C multilayer is higher than that of Si-based multilayers of two kinds of materials. And Mg/SiC multilayer has the highest reflectivity of 43.81% and the narrowest spectral bandwidth of 1.44nm, which proves that Mg/SiC multilayer is more potential for selecting the emission line in extreme ultraviolet solar physics.

Wu, Wenjuan; Zhu, Jingtao; Wang, Fengli; Zhang, Zhong; Wang, Hongchang; Zhang, Shumin; Wang, Zhanshan; Chen, Lingyan; Zhou, Hongjun; Huo, Tonglin

2010-10-01

329

Method to adjust multilayer film stress induced deformation of optics  

Energy Technology Data Exchange (ETDEWEB)

Stress compensating systems that reduces/compensates stress in a multilayer without loss in reflectivity, while reducing total film thickness compared to the earlier buffer-layer approach. The stress free multilayer systems contain multilayer systems with two different material combinations of opposite stress, where both systems give good reflectivity at the design wavelengths. The main advantage of the multilayer system design is that stress reduction does not require the deposition of any additional layers, as in the buffer layer approach. If the optical performance of the two systems at the design wavelength differ, the system with the poorer performance is deposited first, and then the system with better performance last, thus forming the top of the multilayer system. The components for the stress reducing layer are chosen among materials that have opposite stress to that of the preferred multilayer reflecting stack and simultaneously have optical constants that allow one to get good reflectivity at the design wavelength. For a wavelength of 13.4 nm, the wavelength presently used for extreme ultraviolet (EUV) lithography, Si and Be have practically the same optical constants, but the Mo/Si multilayer has opposite stress than the Mo/Be multilayer. Multilayer systems of these materials have practically identical reflectivity curves. For example, stress free multilayers can be formed on a substrate using Mo/Be multilayers in the bottom of the stack and Mo/Si multilayers at the top of the stack, with the switch-over point selected to obtain zero stress. In this multilayer system, the switch-over point is at about the half point of the total thickness of the stack, and for the Mo/Be--Mo/Si system, there may be 25 deposition periods Mo/Be to 20 deposition periods Mo/Si.

Spiller, Eberhard A. (Mount Kisco, NY); Mirkarimi, Paul B. (Sunol, CA); Montcalm, Claude (Livermore, CA); Bajt, Sasa (Sunol, CA); Folta, James A. (Livermore, CA)

2000-01-01

330

Galactosemia presenting as recurrent sepsis.  

UK PubMed Central (United Kingdom)

Galactosemia is a treatable metabolic disorder caused by the deficiency of enzyme galactose-1-phosphate uridyl transferase (GALT) and inherited as an autosomal recessive trait. A case of neonate manifesting with recurrent Escherichia coli sepsis is presented here which turned out to be a classic galactosemia. No other common presenting features were observed in this infant except cataract on slit lamp examination. To the best of our knowledge, there is no case of galactosemia reported in literature which presented with recurrent neonatal sepsis without hepatomegaly, hyperbilirubinemia, bleeding disorder, vomiting, diarrhea, failure to thrive, hypoglycemia, coagulopathy, hemolysis or renal tubular acidosis.

Rathi N; Rathi A

2011-12-01

331

Galactosemia presenting as recurrent sepsis.  

Science.gov (United States)

Galactosemia is a treatable metabolic disorder caused by the deficiency of enzyme galactose-1-phosphate uridyl transferase (GALT) and inherited as an autosomal recessive trait. A case of neonate manifesting with recurrent Escherichia coli sepsis is presented here which turned out to be a classic galactosemia. No other common presenting features were observed in this infant except cataract on slit lamp examination. To the best of our knowledge, there is no case of galactosemia reported in literature which presented with recurrent neonatal sepsis without hepatomegaly, hyperbilirubinemia, bleeding disorder, vomiting, diarrhea, failure to thrive, hypoglycemia, coagulopathy, hemolysis or renal tubular acidosis. PMID:21321007

Rathi, Narendra; Rathi, Akanksha

2011-02-14

332

Anaplastic ependymoma with ependymoblastic multilayered rosettes.  

Science.gov (United States)

Anaplastic ependymoma, World Health Organization grade III, is a malignant glioma with ependymal differentiation characterized by high mitotic activity often accompanied by microvascular proliferation and necrosis, where, generally, much fewer ependymal rosettes are found than in ependymoma, World Health Organization grade II. Ependymal rosettes, forming a single layer of tumor cells, differ from ependymoblastic multilayered rosettes, which are characteristic histologic features of ependymoblastoma, a variant of central nervous system primitive neuroectodermal tumor. Here, we report an autopsy case involving a 24-year-old woman with a frontal lobe tumor, which showed the aggregation of true rosettes with multilayering of tumor cells resembling the ependymoblastoma histology. Molecular and cytogenetic analyses revealed the absence of 19q13.42 amplification, a specific molecular hallmark of ependymoblastoma and embryonal tumor with abundant neuropil and true rosettes, supporting the diagnosis of anaplastic ependymoma. PMID:23791209

Nobusawa, Sumihito; Suzuki, Aya; Nagaishi, Masaya; Isoda, Koji; Ikota, Hayato; Yokoo, Hideaki; Hirato, Junko; Nakazato, Yoichi

2013-06-18

333

Functionalized multilayered graphene platform for urea sensor.  

Science.gov (United States)

Multilayered graphene (MLG) is an interesting material for electrochemical sensing and biosensing because of its very large 2D electrical conductivity and large surface area. We propose a less toxic, reproducible, and easy method for producing functionalized multilayer graphene from multiwalled carbon nanotubes (MWCNTs) in mass scale using only concentrated H(2)SO(4)/HNO(3). Electron microscopy results show the MLG formation, whereas FTIR and XPS data suggest its carboxylic and hydroxyl-functionalized nature. We utilize this functionalized MLG for the fabrication of a novel amperometric urea biosensor. This biosensor shows linearity of 10-100 mg dL(-1), sensitivity of 5.43 ?A mg(-1) dL cm(-2), lower detection limit of 3.9 mg dL(-1), and response time of 10 s. Our results suggest that MLG is a promising material for electrochemical biosensing applications. PMID:22117758

Srivastava, Rajesh K; Srivastava, Saurabh; Narayanan, Tharangattu N; Mahlotra, Bansi D; Vajtai, Robert; Ajayan, Pulickel M; Srivastava, Anchal

2011-12-02

334

Multiple wavelength photolithography for preparing multilayer microstructures  

Energy Technology Data Exchange (ETDEWEB)

The invention relates to a multilayer microstructure and a method for preparing thereof. The method involves first applying a first photodefinable composition having a first exposure wavelength on a substrate to form a first polymeric layer. A portion of the first photodefinable composition is then exposed to electromagnetic radiation of the first exposure wavelength to form a first pattern in the first polymeric layer. After exposing the first polymeric layer, a second photodefinable composition having a second exposure wavelength is applied on the first polymeric layer to form a second polymeric layer. A portion of the second photodefinable composition is then exposed to electromagnetic radiation of the second exposure wavelength to form a second pattern in the second polymeric layer. In addition, a portion of each layer is removed according to the patterns to form a multilayer microstructure having a cavity having a shape that corresponds to the portions removed.

Dentinger, Paul Michael (Livermore, CA); Krafcik, Karen Lee (Livermore, CA)

2003-06-24

335

Magnetic studies in Fe/Zn multilayers  

International Nuclear Information System (INIS)

The structural and magnetic properties of Fe/Zn films prepared by thermal evaporation have been studied by means of X-ray diffraction, vibrating-sample magnetometry and ferromagnetic resonance (FMR). For Fe layer thickness smaller than 20 A the saturation magnetization decreases with decreasing Fe thickness, which is an indication of the island growth of Zn and Fe-Zn interdiffusion at the layer interfaces. The effective field magnetization 4?Meff of the Fe/Zn multilayers was determined from the FMR data in a rotating external magnetic field. The interface anisotropy constant of the Fe/Zn multilayers, KS, is found to be 1.0 erg/cm2 at 300 K. This indicates the presence of a large perpendicular interface anisotropy and this may suggest that the largest part of KS originates from lattice misfit strain.

2003-01-01

336

Recurrent malignant salivary gland neoplasms.  

UK PubMed Central (United Kingdom)

Recurrent salivary gland malignancies present difficult therapeutic decisions and poor prognosis in many instances, and treatment becomes of a palliative nature only. As many of the salivary gland malignancies we see are of the recurrent type, the following study was done to determine the efficacy of a vigorous attempt at retreatment. During the period January 1, 1960, through December 31, 1984, 352 patients with major and minor salivary gland tumors were evaluated at our institution. There were 149 benign lesions and 203 patients with malignant tumors. Of these, 99 patients had recurrent and metastatic tumors that had been treated initially elsewhere. Thirty-three of these patients were able to be treated with curative intent: surgery, 21; surgery plus radiation, 9; radiation therapy alone, 2; and radiation plus chemotherapy, 1. The 5 year survival with no evidence of disease was achieved in three patients with surgery alone and two patients with surgery plus radiation therapy. The group of five patients was comprised of two patients with adenoid cystic carcinomas of the parotid, one with intermediate grade mucoepidermoid carcinoma of the parotid, one, sebaceous cell carcinoma of the parotid, and one, adenoid cystic carcinoma of an accessory salivary gland. The results of this study serve to re-emphasize the relative poor yield of attempts at retreatment of loco-regional recurrence of salivary gland tumors.

Rodriguez-Bigas MA; Sako K; Razack MS; Shedd DP; Bakamjian VY; Castillo NB; Rao U

1989-10-01

337

Recurrent malignant salivary gland neoplasms.  

Science.gov (United States)

Recurrent salivary gland malignancies present difficult therapeutic decisions and poor prognosis in many instances, and treatment becomes of a palliative nature only. As many of the salivary gland malignancies we see are of the recurrent type, the following study was done to determine the efficacy of a vigorous attempt at retreatment. During the period January 1, 1960, through December 31, 1984, 352 patients with major and minor salivary gland tumors were evaluated at our institution. There were 149 benign lesions and 203 patients with malignant tumors. Of these, 99 patients had recurrent and metastatic tumors that had been treated initially elsewhere. Thirty-three of these patients were able to be treated with curative intent: surgery, 21; surgery plus radiation, 9; radiation therapy alone, 2; and radiation plus chemotherapy, 1. The 5 year survival with no evidence of disease was achieved in three patients with surgery alone and two patients with surgery plus radiation therapy. The group of five patients was comprised of two patients with adenoid cystic carcinomas of the parotid, one with intermediate grade mucoepidermoid carcinoma of the parotid, one, sebaceous cell carcinoma of the parotid, and one, adenoid cystic carcinoma of an accessory salivary gland. The results of this study serve to re-emphasize the relative poor yield of attempts at retreatment of loco-regional recurrence of salivary gland tumors. PMID:2796352

Rodriguez-Bigas, M A; Sako, K; Razack, M S; Shedd, D P; Bakamjian, V Y; Castillo, N B; Rao, U

1989-10-01

338

On a recurrence of PCA  

International Nuclear Information System (INIS)

[en] The possibility of recurrence of the unique sporadic phenomenon - polar-cap absorption (PCA) - according to the full set of events for 1938-1986 is investigated. Repetition periods of PCA during 26-27 days and 32-33 days are detected by the method of time diagrams

1988-01-01

339

Recurrent dermatitis from jellyfish envenomation.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Jellyfish envenomation can cause an immediate local skin reaction, which is usually a painful linear vesiculourticarial eruption. Persistent, delayed, or recurrent dermatitis is less common. Because jellyfish sting reactions and their management are unfamiliar to family physicians, we describe a cas...

Menahem, S.; Shvartzman, P.

340

Ovarian irradiation in recurrent endometriosis  

International Nuclear Information System (INIS)

[en] We describe a case of a young woman with a history of an aplastic anaemia in which pelvic radiotherapy was used successfully in the management of a recurrent and inoperable endometriosis. The use of therapeutic pelvic or ovarian irradiation in endometriosis may be considered, when surgical and medical treatments have been exhausted and have failed. (authors)

2005-01-01

 
 
 
 
341

Recurrent Kikuchi-Fujimoto disease  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We report the case of a 27-year-old, UK-born, Asian woman who suffered a rare recurrence of Kikuchi-Fujimoto disease. She presented with tender lymphadenopathy of the neck, fever and a prodrome of flu-like symptoms. She had a past medical history of biopsy-proven Kikuchi-Fujimoto disease of her righ...

Spooner, Brendan Boyd; Rahman, Imdadur; Langford, Nigel; Ferner, Robin E

342

Recurrence Formulas for Fibonacci Sums  

CERN Document Server

In this article we present a new recurrence formula for a finite sum involving the Fibonacci sequence. Furthermore, we state an algorithm to compute the sum of a power series related to Fibonacci series, without the use of term-by-term differentiation theorem

Brandao, Adilson J V

2008-01-01

343

Recurrent Processing during Object Recognition.  

UK PubMed Central (United Kingdom)

How does the brain learn to recognize objects visually, and perform this difficult feat robustly in the face of many sources of ambiguity and variability? We present a computational model based on the biology of the relevant visual pathways that learns to reliably recognize 100 different object categories in the face of naturally occurring variability in location, rotation, size, and lighting. The model exhibits robustness to highly ambiguous, partially occluded inputs. Both the unified, biologically plausible learning mechanism and the robustness to occlusion derive from the role that recurrent connectivity and recurrent processing mechanisms play in the model. Furthermore, this interaction of recurrent connectivity and learning predicts that high-level visual representations should be shaped by error signals from nearby, associated brain areas over the course of visual learning. Consistent with this prediction, we show how semantic knowledge about object categories changes the nature of their learned visual representations, as well as how this representational shift supports the mapping between perceptual and conceptual knowledge. Altogether, these findings support the potential importance of ongoing recurrent processing throughout the brain's visual system and suggest ways in which object recognition can be understood in terms of interactions within and between processes over time.

O'Reilly RC; Wyatte D; Herd S; Mingus B; Jilk DJ

2013-01-01

344

Recurrent primary mesenteric venous thrombosis.  

UK PubMed Central (United Kingdom)

We have reported a case of recurrent primary mesenteric venous thrombosis resulting in small bowel infarction. Resection of necrotic bowel, anastomosis, and postoperative anticoagulation remain the cornerstone of management. Delay in diagnosis and treatment contributes to the high mortality. A history of peripheral thrombosis, antithrombin III deficiency, hypovolemia, or carcinoma in susceptible patients with abdominal pain should arouse suspicion of ischemic bowel.

Dada FB; Balan AD

1987-10-01

345

Analysis of Fracture Behaviour of Multilayer Pipes.  

Czech Academy of Sciences Publication Activity Database

. Ro?. 36, ?. 5 (2007), s. 207-212. ISSN 1465-8011.[Plastic Pipes /13./. Washington, D. C., 02.10.2006-05.10.2006]Grant CEP: GA ?R GA106/07/1284Výzkumný zám?r: CEZ:AV0Z20410507Klí?ová slova: multi-layer pipesKód oboru RIV: JL - Únava materiálu a lomová mechanikaImpakt faktor: 0.431, rok: 2007

Nezbedová, E.; Knésl, Zden?kG; Vlach, B.

346

Structural studies of titanium oxide multilayers  

International Nuclear Information System (INIS)

[en] Multilayers of titanium oxide on conductive glass (silica, covered with indium/tin and tin oxides) were obtained by different methods (from suspension, by sol-gel, by vacuum sputtering). X-ray diffraction and positron annihilation depth-resolved characterization of these samples are presented. The data allow us to determine optimal deposition parameters, in order to obtain the anatase phase, important in practical applications in photoelectrochemical cells. (author)

2005-01-01

347

75 FR 70714 - Multilayered Wood Flooring From the People's Republic of China: Initiation of Antidumping Duty...  

Science.gov (United States)

...Administration [A-570-970] Multilayered Wood Flooring From the People's Republic of China...concerning imports of multilayered wood flooring from the People's Republic of China...Countervailing Duties: Multilayered Wood Flooring from the People's Republic of...

2010-11-18

348

78 FR 32367 - Multilayered Wood Flooring From the People's Republic of China; Preliminary Results of...  

Science.gov (United States)

...Administration [A-570-970] Multilayered Wood Flooring From the People's Republic of China...antidumping duty order on multilayered wood flooring (``MLWF'') from the People's...New Shipper Review: Multilayered Wood Flooring from the People's Republic of...

2013-05-30

349

76 FR 92 - Multilayered Wood Flooring From the People's Republic of China: Postponement of Preliminary...  

Science.gov (United States)

...C-570-971] Multilayered Wood Flooring From the People's Republic of...investigation of multilayered wood flooring from the People's Republic of...PRC''). See Multilayered Wood Flooring From the People's Republic...

2011-01-03

350

76 FR 19034 - Multilayered Wood Flooring From the People's Republic of China: Preliminary Affirmative...  

Science.gov (United States)

...Administration [C-570-971] Multilayered Wood Flooring From the People's Republic of China...producers and exporters of multilayered wood flooring from the People's Republic of China...Federal Register. See Multilayered Wood Flooring from the People's Republic of...

2011-04-06

351

76 FR 13357 - Multilayered Wood Flooring from the People's Republic of China: Postponement of Preliminary...  

Science.gov (United States)

...Administration [A-570-970] Multilayered Wood Flooring from the People's Republic of China...duty investigation on multilayered wood flooring from the People's Republic of China...1\\ See Multilayered Wood Flooring from the People's Republic of...

2011-03-11

352

Interlayer exchange coupling in (Ga,Mn)As based multilayers  

Energy Technology Data Exchange (ETDEWEB)

Exhibiting antiferromagnetic interlayer coupling in dilute magnetic semiconductor multilayers is essential for the realisation of magnetoresistances analogous to giant magnetoresistance in metallic multilayer structures. In this work we use a mean-field theory of carrier induced ferromagnetism to explore possible (Ga,Mn)As based multilayer structures that might yield antiferromagnetic coupling. (copyright 2006 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Giddings, A.D.; Gallagher, B.L. [School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD (United Kingdom); Jungwirth, T. [School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD (United Kingdom); Institute of Physics ASCR, Cukrovarnicka 10, 162 53 Praha 6 (Czech Republic)

2006-07-01

353

Localized phonon modes in Fe/Pd multilayers  

Energy Technology Data Exchange (ETDEWEB)

The Rayleigh mode and up to six higher order localized acoustic (Sezawa) surface modes have been observed in Fe/Pd multilayers by Brillouin scattering. The effective elastic constants of the multilayers have been determined from a fit of the measured mode dispersions. With decreasing modulation wavelength of the multilayers from 87 A to 33 A the elastic constant c/sub 11/ shows an interface induced softening of up to 20%.

Baumgart, P.; Hillebrands, B.; Mock, R.; Guentherodt, G.; Boufelfel, A.; Falco, C.M.

1986-01-01

354

Surface Brillouin scattering in semiconductor Fibonacci multilayers  

Science.gov (United States)

Brillouin spectra from surface (Rayleigh) acoustic waves in a-Si:H/a-SiNx:H (x~=0.94) Fibonacci multilayers have been measured with a tandem multipass Fabry-Pérot interferometer. To make a detailed analysis for the observed surface (Rayleigh) waves, following Merlin et al. [Phys. Rev. Lett. 55, 1678 (1985)] and Dharma-wardana et al. [Phys. Rev. Lett. 58, 1761 (1987)], we have formulated the propagation of surface acoustic waves parallel to the surface of the quasiperiodic multilayers using the Fourier-transform method in the long-wavelength regime. We found that the obtained Brillouin spectra can be accounted for by this new derivation of the Fourier transform of the surface acoustic waves, but a rather fascinating feature for the phonon frequency is that it is slightly modified by quasiperiodic indices (n,m) or p. Such a modulation is attributed to the existence of a small but nonvanishing acoustic impedance. Our theoretical approach gives the correct order of amplitude modulation for surface (Rayleigh) waves within an error of <1%. We thereby obtain an overall understanding of the elastic properties of the Fibonacci multilayers.

Xia, Hua; Zhang, X. K.; Chen, K. J.; Cheng, G. X.; Feng, D.; Socino, G.; Palmieri, L.; Carlotti, G.; Fioretto, D.; Nizzoli, F.

1990-12-01

355

Ultrasonic wave propagation in multilayered piezoelectric substrates  

Energy Technology Data Exchange (ETDEWEB)

Due to the increasing demand for higher operating frequency, lower attenuation, and stronger piezoelectricity, use of the layered structure has become necessary. Theoretical studies are carried out for ultrasonic waves propagating in the multilayered piezoelectric substrates. Each layer processes up to as low as monoclinic symmetry with various thickness and orientation. A plane acoustic wave is assumed to be incident, at varied frequency and incidence angle, from a fluid upon a multilayered substrate. Simple analytical expressions for the reflection and transmission coefficients are derived from which all propagation characteristics are identified. Such expressions contain, as a by-product, the secular equation for the propagation of free harmonic waves on the multilayered piezoelectric substrates. Solutions are obtained for the individual layers which relate the field variables at the upper layer surfaces. The response of the total system proceeds by satisfying appropriate interfacial conditions across the layers. Based on the boundary conditions, two cases, {open_quotes}shorted{close_quotes} and {open_quotes}free{close_quotes}, are derived from which a so-called piezoelectric coupling factor is calculated to show the piezoelectric efficiency. Our results are rather general and show that the phase velocity is a function of frequency, layer thickness, and orientation.

Chien, H.T.; Sheen, S.H.; Raptis, A.C.

1994-04-11

356

Infrared Transmission in Porous Silicon Multilayers  

Directory of Open Access Journals (Sweden)

Full Text Available Porous silicon is a nanostructured material and exhibits efficient photo- and electro-luminescence in the visible range at room temperature, as well as a tunable refractive index determined by its porosity. Porous silicon samples can be obtained by etching a crystalline silicon wafer in a solution of hydrofluoric acid. In this work, we report the fabrication of porous silicon multilayers alternating layers with high and low porosities, which correspondingly produce low and high refractive indices. The free-standing multilayers were formed following three different sequences: periodic, Fibonacci and ThueMorse. These structures were verified by scanning electron microscopy and their infrared transmission spectra were measured by means of Fourier-transform infrared spectroscopy. On the other hand, we calculate the light transmittance of porous silicon multilayers by using the transfer matrix method for all directions of incidence and a wide range of wavelengths. The experimental measurements are compared with theoretical results and a good agreement is observed. In addition, an analysis of infrared absorption peaks due to the molecular vibrations at pore surfaces reveals the presence of hydrogen and oxygen atoms.

Alessio Palavicini; Chumin Wang

2013-01-01

357

Applications for superconductor-insulator multilayers  

Science.gov (United States)

Superconductor/insulator (SI) superlattices may be viewed as repeated (or stacked) SIS junctions connected in series. Such superlattices have a number of promising applications which we will survey. In the weakly coupled (tunnel junction) limit the possibility of fabricating high resolution X-ray detectors is being studied. For more strongly coupled junctions involving Josephson coupling, possible applications are numerous. The suggestion of Auvil and Ketterson that an SI multilayer would function as an efficient radiation source (due to coherent radiation from the layers and an increased junction phase velocity) has yet to be studied experimentally. Rippert and Ketterson have proposed that a phonon maser might be realized involving 2(Delta) recombination phonons and internal feedback via the superlattice Bragg mirror. Lomatch et al. have suggested that the added kinetic inductance of a multilayer could be used to eliminate stripline inductors from a Josephson transmission line. Finally multilayer SI tapes have been shown to have an enhanced critical current density, Jc. The mechanisms involved in the above devices and the status of efforts to fabricate them are reviewed.

Ketterson, John B.; Rippert, Edward D.; Song, Shenian N.; Lomatch, Susanne; Maglic, Stevan R.; Wang, H. C.; Morgan, D. J.; Ulmer, Melville P.

1994-06-01

358

Performance of multilayer coated silicon pore optics  

DEFF Research Database (Denmark)

The requirements for the IXO (International X-ray Observatory) telescope are very challenging in respect of angular resolution and effective area. Within a clear aperture with 1.7 m > R > 0.25 m that is dictated by the spacecraft envelope, the optics technology must be developed to satisfy simultaneously requirements for effective area of 2.5 m2 at 1.25 keV, 0.65 m2 at 6 keV and 150 cm2 at 30 keV. The reflectivity of the bare mirror substrate materials does not allow these requirements to be met. As such the IXO baseline design contains a coating layout that varies as a function of mirror radius and in accordance with the variation in grazing incidence angle. The higher energy photon response is enhanced through the use of depth-graded multilayer coatings on the inner radii mirror modules. In this paper we report on the first reflectivity measurements of wedged ribbed silicon pore optics mirror plates coated with a depth graded W/Si multilayer. The measurements demonstrate that the deposition and performance of the multilayer coatings is compatible with the SPO production process.

Ackermann, M. D.; Collon, M. J.

2010-01-01

359

Atom probe analysis of planar multilayer structures  

Energy Technology Data Exchange (ETDEWEB)

Atom probe field ion microscopy has been used to analyze a planar-deposited layered structure in plan view. The specimens were prepared with a newly developed method that involves a combination of photolithography and focused ion-beam milling. A multilayer structure consisting of (left brace)Ta/CoFe/(Cu/CoFe){sub 15}/Ru/(CoFe/Ru){sub 5}/Ru/NiFe{r_brace} was sputter deposited for use as a test stack. The corresponding thicknesses of these layers were 7/13(3/3)/50/(3/1)/50/150 nm. The nanometer-scale periodicity of the Cu/CoFe stack is readily apparent in transmission electron microscopy images of a field ion specimen fabricated from this material, suggesting that the specimen preparation procedure does not lead to destruction of the multilayer structure. Atom probe analysis of the bulk NiFe layer and the Ru/NiFe interface revealed the distribution of impurity atoms in the film, and these may affect the magnetic properties of the multilayers. Whereas a uniform distribution of C, N and Ar was observed, segregation of O was observed in the NiFe layer within {approx}0.25 nm of the interphase interface, with a concentration greater than 20 times that found in the bulk of the NiFe layer. (c) 2000 American Institute of Physics.

Larson, D. J. [Recording Head Operations, Seagate Technology, 7801 Computer Avenue South, Minneapolis, Minnesota 55435 (United States); Martens, R. L. [Department of Materials Science and Engineering, University of Wisconsin, Madison, Wisconsin 53706 (United States); Kelly, T. F. [Department of Materials Science and Engineering, University of Wisconsin, Madison, Wisconsin 53706 (United States); Miller, M. K. [Metals and Ceramics Division, Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, Tennessee 37831 (United States); Tabat, N. [Recording Head Operations, Seagate Technology, 7801 Computer Avenue South, Minneapolis, Minnesota 55435 (United States)

2000-05-01

360

Does circumcision influence recurrences in herpes genitalis?  

Directory of Open Access Journals (Sweden)

Full Text Available Background and Aims: The effect of therapeutic circumcision in men for preventing recurrences of herpes genitalis remains largely unelucidated despite its well documented albeit conflicting role in reducing the risk of acquiring sexually transmitted infections, including genital herpes. Methods: Twenty volunteer adult males with a history of recurrent herpes genitalis were included in the study after informed consent and circumcision was carried out. Twenty more adult males having recurrent herpes genitalis and registered in the clinic during the same period were selected as controls. All patients and controls were followed-up for recurrences of herpes genitalis. Results and Conclusions: Six patients and six controls did not follow-up. Seven patients reported no recurrences during 3-18 years, seven patients had two to six recurrences during 11-27 years of postcircumcision follow-up, 0.0080 (average) recurrences per person per year as compared with 0.20 (average) recurrences per person per year recorded before the circumcision. Two patients had first recurrence 11 years after the circumcision. In comparison, 14 controls had 0.17 (average) recurrences per person per year, comparable with the number of recurrences in uncircumcised patients, and frequently at shorter intervals. Despite being a small study, the circumcision appears to reduce the number of recurrences on an average and evidently prolongs the disease-free period in between two recurrences.

Jerath V; Mahajan Vikram

2009-01-01

 
 
 
 
361

Recurrence of benign paroxysmal positional vertigo.  

UK PubMed Central (United Kingdom)

OBJECTIVE: To determine the recurrence rate of benign positional paroxysmal vertigo (BPPV) and the factors associated to such recurrences. STUDY DESIGN: Prospective study. METHOD: Sixty-nine consecutive patients treated for first episode of BPPV. Study period: 63 months. Mean follow-up: 47 months. RESULTS: The recurrence rate was 27%. Fifty percent of recurrences occurred in the first 6 months. Nineteen patients had 1 or more recurrence of BPPV; 10 had 1 recurrence, 7 patients had 2, and 2 patients had 3 recurrences. There was no significant difference in the recurrence rate according to sex, age, side, cause of BPPV, or instability after successful treatment. Multi-canal BPPV (log-rank, p = 0.024) and anterior canal BPPV (log-rank, p = 0.029) showed a significantly greater tendency to recur and to do so earlier. There was a significant difference in time to recurrence related to the number of maneuvers used to resolve the initial BPPV episode (log-rank, p = 0.023). Except for cases of BPPV secondary to labyrinthitis or neurolabyrinthitis, at least 70% of the recurrences affected a different side and/or different canal than the primary BPPV. CONCLUSION: The recurrence rate of BPPV is 27%, and relapse largely occurs in the first 6 months. When BPPV recurrence is suspected, every canal on both sides must be investigated because it is the BPPV syndrome that recurs, rather than BPPV affecting a particular side or canal. Complex cases of BPPV have a greater risk of recurrence.

Pérez P; Franco V; Cuesta P; Aldama P; Alvarez MJ; Méndez JC

2012-04-01

362

Management of recurrent acute otitis media in children: systematic review of the effect of different interventions on otitis media recurrence, recurrence frequency and total recurrence time.  

UK PubMed Central (United Kingdom)

OBJECTIVE: To conduct a systematic review comparing the effect of three interventions (prophylactic antibiotics, tympanostomy tube insertion and adenoidectomy) on otitis media recurrence, recurrence frequency and total recurrence time. METHODS: Literature on recurrent otitis media was identified using the PubMed and Scopus search engines for the period January 1990 to March 2011. A hand search of the reference lists of relevant articles and textbooks was conducted to identify additional studies. Randomised, controlled trials with a minimum of 40 children and follow up of at least 12 months were included. RESULTS: Eighteen publications were identified. Each was assessed using preset inclusion criteria; seven publications met these criteria. CONCLUSION: Prophylactic antibiotics are effective in reducing otitis media recurrence, recurrence frequency and total recurrence time. Tympanostomy tube insertion failed to reduce the prevalence of otitis media recurrence, but reduced the recurrence frequency and total recurrence time. Adenoidectomy reduced otitis media recurrence; results on otitis media recurrence frequency differed but on average there was a reduction; however, the two studies with relevant data on total recurrence time had contradictory results.

Cheong KH; Hussain SS

2012-09-01

363

The first example of multilayer films with thermochromic properties  

International Nuclear Information System (INIS)

A novel thermochromic multilayer film containing polyoxometalate cluster K12.5Na1.5[NaP5W30O110] has been fabricated by layer-by-layer self-assembly method. In case of the multilayer film, the color changes gradually from yellowish to blue when it is subjected to temperatures between 120 deg. C and 180 deg. C for a period of time, and the multilayer film could be bleached in air at room temperature to recover its initial state. The novel thermochromic multilayer may be of practical benefit in the development of thermosensors, which would represent promising materials for future applications.

2004-01-01

364

Ultrahydrophobicity of Polydimethylsiloxanes-Based Multilayered Thin Films  

Directory of Open Access Journals (Sweden)

Full Text Available The formation of polydimethylsiloxanes (PDMSs)-based layer-by-layer multilayer ultrathin films on charged surfaces prepared from water and phosphate buffer solutions has been investigated. The multilayer films prepared under these conditions showed different surface roughness. Nanoscale islands and network structures were observed homogeneously on the multilayer film prepared from pure water solutions, which is attributing to the ultrahydrobic property of the multilayer film. The formation of nanoscale islands and network structures was due to the aggregation of PDMS-based polyelectrolytes in water. This work provides a facile approach for generating ultrahydrophobic thin films on any charged surfaces by PDMS polyelectrolytes.

Hongyan Gao; Karen Xiaohe Xu; Bin Chen; Li-Zhu Wu; Chen-Ho Tung; Hai-Feng Ji

2009-01-01

365

Multilayer relaxation in metallic surfaces as demonstrated by LEED analysis  

Energy Technology Data Exchange (ETDEWEB)

Theoretical motivations are reviewed for investigation of multilayer relaxation in relatively simple metallic surfaces. Results from LEED analyses are presented which serve to demonstrate that multilayer relaxation measurably exists in Cu(100) and Cu(110) surfaces. The results from two independent LEED analyses for Cu(110) are shown to be in much better agreement with each other than the LEED results are with multilayer relaxation results obtained by high energy ion scattering. Multilayer relaxation results for other metallic surfaces also are reviewed briefly, and all available results are discussed in relationship to those obtained by a theoretical, model-type, inquiry of Landman, Hill and Mostoller.

Davis, H.L.; Noonan, J.R.

1982-07-01

366

Multilayer relaxation in metallic surfaces as demonstrated by LEED analysis  

International Nuclear Information System (INIS)

Theoretical motivations are reviewed for investigation of multilayer relaxation in relatively simple metallic surfaces. Results from LEED analyses are presented which serve to demonstrate that multilayer relaxation measurably exists in Cu(100) and Cu(110) surfaces. The results from two independent LEED analyses for Cu(110) are shown to be in much better agreement with each other than the LEED results are with multilayer relaxation results obtained by high energy ion scattering. Multilayer relaxation results for other metallic surfaces also are reviewed briefly, and all available results are discussed in relationship to those obtained by a theoretical, model-type, inquiry of Landman, Hill and Mostoller

1982-08-27

367

Recurrence after groin hernia repair-revisited.  

UK PubMed Central (United Kingdom)

One of the commonly performed operations all over the world is hernia repair. Various open and laparoscopic procedures are available now for hernia repair. They are judged mainly by the recurrence rate following operation. The recognition of the causes of recurrence makes their prevention/elimination possible. Articles on hernia recurrence published in various journals over the past 40 years have been analysed. This review article mainly focuses on the causes of recurrence of hernia and their prevention. The causes of recurrence following open and laparoscopic hernia repair have been analysed. In open repair, early recurrences are due to faults in operative technique and postoperative infection. Late recurrences are due to patient factors like collagen defects, age and medical morbidities. In laparoscopic repair, technical aspects of surgery like dissection, mesh placement and fixation are the important factors which decide hernia recurrence.

Gopal SV; Warrier A

2013-01-01

368

[Treatment for recurrent hairy cell leukemia].  

UK PubMed Central (United Kingdom)

AIM: To give data on the frequency of recurrent hairy cell leukemia (HCL) and to characterize the immediate and late results of its treatment in this group of patients. MATERIALS AND METHODS: The data on the frequency of recurrences were analyzed in 165 patients with HCL after remission achieved by the purine analogue cladribin in the period 1995 to 2011. The treatment of recurrent HCL included splenectomy, interferon-a, cladribin, and rituximab. RESULTS: After a course of cladribin therapy, the total frequency of recurrent HCL was 22%. The high (47%) frequency of recurrences was found in young patients (less than 45 years) as compared to that (9%) in older patients. A combination of cladribin and rituximab showed a high efficacy in treating the early recurrence of HCL. CONCLUSION: The differences found in the frequency of recurrences give grounds to incorporate rituximab into the standard therapy regimen for HCL in young patients and in patients with early disease recurrence.

Al'-Radi LS; Pivnik AV; Zingerman BV; Kravchenko SK

2012-01-01

369

Properties of Ni/Co multilayers as a function of the number of multilayer repetitions  

International Nuclear Information System (INIS)

We study the static and dynamic properties of magnetic multilayers with perpendicular magnetic anisotropy (PMA) composed of alternating ultrathin layers of Co and Ni. In particular, the evolution of PMA and the Gilbert damping parameter is investigated as a function of thickness using ferromagnetic resonance. We find a rather small Gilbert damping constant ? = 0.014 which is almost independent of the number of multilayer repetitions. In addition, the out-of-plane angular dependence of the resonance fields can only be explained when a second order term for the uniaxial out-of-plane anisotropy is included in the energy density. (paper)

2013-05-01

370

Giant recurrent retroperitoneal liposarcoma presenting as a recurrent inguinal hernia  

Directory of Open Access Journals (Sweden)

Full Text Available Retroperitoneal liposarcoma presenting as an inguinal hernia is a rare entity. We present the first case of Giant recurrent liposarcoma presenting as a recurrent inguinal hernia in a 40-year-old male. Physical examination showed an irreducible lump in the right inguinal region and a scar in the right lumbar and right inguinal region. Computed tomography (CT) scan of abdomen revealed it to be a retro peritoneal mass extending into the right inguinal region along and involving the cord structures. Wide local excision of the tumour with right orchidectomy and inguinal hernioplasty was performed. Histo-pathology confirmed it to be a liposarcoma. Patient received postoperative radio therapy. Follow up of two years has shown him to be disease free. Retroperitoneal liposarcoma can grow along cord structures into the inguinal canal and mimic an irreducible indirect inguinal hernia.

Ajay H. Bhandarwar; Girish D. Bakhshi; Ashok D. Borisa; Sachin S. Shenoy; Channabasappa G. Kori; Sameer Vora

2011-01-01

371

Recurrent and non-recurrent trajectories in a chaotic system  

Directory of Open Access Journals (Sweden)

Full Text Available The dynamics of a system subjected to a potential equal to the sum of the Henon-Heiles potential and that of thehydrogen atom in a uniform magnetic field has been studied. Depending on the energy of the system, the Poincaresurface is characterised by regions of regular motion, appearing and disappearing regions of regular motion, regions ofrecurrent (regular and chaotic) trajectories and those of non-recurrent trajectories.

A. B. Adeloye; A. O. Akala

2010-01-01

372

Risk factors of recurrent lumbar disk herniation  

Science.gov (United States)

Background: Recurrent lumbar disc herniation (LDH) is a common cause of poor outcomes after lumbar discectomy surgery. Studies focused on risk factors of true recurrent disk herniation at the same level and side, are few. The aim of current study is to evaluate risk factors of recurrent disc herniation in Iranian population. Materials and Methods: We retrospectively reviewed 40 patients with recurrent disc herniation and 120 patients without recurrence to evaluate possible risk factors for herniation recurrence. A clinically significant recurrent herniation was defined as a disc herniation causing leg pain with radiographic (MRI) evidence of disc material at the same side and level of the index surgery causing impingement, compression, or deviation of nerve tissue. A series of patients without recurrence was used for comparison to identify possible risk factors for recurrent LDH. Results: There was significant difference between groups with and without LDH in sex (P = 0.003), smoking habit (P = 0.004), height (P = 0.04), weight (P = 0.006) and occupational characteristic (P < 0.001). By putting these differences in logistic regression analysis, it showed that gender (male), taller height, heavy works and being smoker could predict lumbar disc herniation recurrence. Conclusion: Considering sex, smoking and heavy works as predictors of recurrent LDH, surgeons should advice their patients to limit hard work and put away smoking especially in tall and male ones to prevent LDH recurrence.

Shimia, Mohammad; Babaei-Ghazani, Arash; Sadat, Bina Eftekhar; Habibi, Behnaz; Habibzadeh, Afshin

2013-01-01

373

Risk factors of recurrent lumbar disk herniation.  

UK PubMed Central (United Kingdom)

BACKGROUND: Recurrent lumbar disc herniation (LDH) is a common cause of poor outcomes after lumbar discectomy surgery. Studies focused on risk factors of true recurrent disk herniation at the same level and side, are few. The aim of current study is to evaluate risk factors of recurrent disc herniation in Iranian population. MATERIALS AND METHODS: We retrospectively reviewed 40 patients with recurrent disc herniation and 120 patients without recurrence to evaluate possible risk factors for herniation recurrence. A clinically significant recurrent herniation was defined as a disc herniation causing leg pain with radiographic (MRI) evidence of disc material at the same side and level of the index surgery causing impingement, compression, or deviation of nerve tissue. A series of patients without recurrence was used for comparison to identify possible risk factors for recurrent LDH. RESULTS: There was significant difference between groups with and without LDH in sex (P = 0.003), smoking habit (P = 0.004), height (P = 0.04), weight (P = 0.006) and occupational characteristic (P < 0.001). By putting these differences in logistic regression analysis, it showed that gender (male), taller height, heavy works and being smoker could predict lumbar disc herniation recurrence. CONCLUSION: Considering sex, smoking and heavy works as predictors of recurrent LDH, surgeons should advice their patients to limit hard work and put away smoking especially in tall and male ones to prevent LDH recurrence.

Shimia M; Babaei-Ghazani A; Sadat BE; Habibi B; Habibzadeh A

2013-04-01

374

Development of EUV multilayer mirrors for astronomical observation in IPOE  

Science.gov (United States)

Three kinds of multilayer mirrors were developed for solar observation and earth's magnetosphere observation at Extreme Ultraviolet (EUV) wavelength region. The first one is Mo/Si multilayer mirror, designed for solar Fe-XII emission line at wavelength of 19.5nm. The reflectivities are in the range of 38.7~42.9%, measured at National Synchrotron Radiation Laboratory (NSRL), Hefei, China. The second high-reflective multilayer is designed for solar He-II radiation at 30.4 nm. At this wavelength, SiC/Mg multilayers were investigated, and as high as 50.0% measured reflectivity was obtained at incident angle of 10°. Aperiodic SiC/Mg multilayers were also designed for wide angular ranges of 15-22° and 12-21°. The third multilayer mirror was a dual-function mirror used for earth's magnetosphere observation, which requires high-reflective for He-II emission line at wavelength of 30.4nm but low-reflectance at 58.4nm from ionosphere He-I emission. Using aperiodic SiC/Mg multilayer stack, the dual-function multilayer mirror was designed by genetic algorithm. Compared to periodic multilayer, the dual-function multilayer suppresses the reflectivity for He-I at 58.4nm from 2.2% to 0.1%, without loss of the reflection for He-II at 30.4nm, significantly. These multilayer mirrors were all prepared by magnetron sputtering system in IPOE, and measured at NSRL, China.

Zhu, Jingtao; Wang, Xiaoqiang; Xu, Jing; Chen, Rui; Huang, Qiushi; Bai, Liang; Zhang, Zhong; Wang, Zhanshan; Chen, Lingyan

2008-08-01

375

A perspective on recurrent vertigo.  

UK PubMed Central (United Kingdom)

The recurrent nature of the 3 most common vestibulopathies suggests a recurrent cause. Histopathology in temporal bones from patients with these syndromes - vestibular neuronitis (VN, n = 7), Ménière's disease (MD, n = 8) and benign paroxysmal positional vertigo (BPPV, n = 5) - shows focal degeneration of vestibular nerve axons and degenerated nearby facial nerve meatal ganglion cells. Transmission electron microscopic confirmation of intracytoplasmic viral particles in surgically excised vestibular nerves from patients with VN and MD support a viral etiology in these vestibulopathies. Antiviral treatment of these syndromes in a series of 211 patients with a 3- to 8-year follow-up resulted in complete control of vertigo in VN (88%), MD (90%) and BPPV (60%).

Gacek RR

2013-01-01

376

A perspective on recurrent vertigo.  

Science.gov (United States)

The recurrent nature of the 3 most common vestibulopathies suggests a recurrent cause. Histopathology in temporal bones from patients with these syndromes - vestibular neuronitis (VN, n = 7), Ménière's disease (MD, n = 8) and benign paroxysmal positional vertigo (BPPV, n = 5) - shows focal degeneration of vestibular nerve axons and degenerated nearby facial nerve meatal ganglion cells. Transmission electron microscopic confirmation of intracytoplasmic viral particles in surgically excised vestibular nerves from patients with VN and MD support a viral etiology in these vestibulopathies. Antiviral treatment of these syndromes in a series of 211 patients with a 3- to 8-year follow-up resulted in complete control of vertigo in VN (88%), MD (90%) and BPPV (60%). PMID:23796949

Gacek, Richard R

2013-06-21

377

Recurrent gossypiboma in the thigh  

Energy Technology Data Exchange (ETDEWEB)

Gossypiboma, an iatrogenic mass lesion caused by a retained surgical sponge is an extremely rare event following musculoskeletal procedures. This entity is therefore a very unusual experience and can create considerable confusion. Unsuspecting surgeons may thus be caught out by this unlikely presentation. We present our experience with a recurrent gossypiboma in the thigh occurring several years after surgical evacuation of a similar gossypiboma from the same anatomic location with interval resolution of symptoms. The purpose of this case report is to highlight the possibility of a ''recurrent'' soft tissue mass occurring for reasons other than a neoplasm. In the absence of a definitive biopsy diagnosis of tumor in patients who have undergone prior surgical procedures in that area, it may be more prudent to adopt a conservative surgical resection rather than a conventional radical resection as warranted by the dramatic clinical presentation mimicking a soft tissue sarcoma. (orig.)

Puri, Ajay; Anchan, Chetan; Agarwal, Manish G. [Tata Memorial Hospital, Department of Orthopaedic Oncology, Mumbai (India); Jambhekar, Nirmala A. [Tata Memorial Hospital, Department of Pathology, Mumbai (India); Badwe, Rajendra A. [Tata Memorial Hospital, Department of Surgical Oncology, Mumbai (India)

2007-06-15

378

Recurrent gossypiboma in the thigh  

International Nuclear Information System (INIS)

Gossypiboma, an iatrogenic mass lesion caused by a retained surgical sponge is an extremely rare event following musculoskeletal procedures. This entity is therefore a very unusual experience and can create considerable confusion. Unsuspecting surgeons may thus be caught out by this unlikely presentation. We present our experience with a recurrent gossypiboma in the thigh occurring several years after surgical evacuation of a similar gossypiboma from the same anatomic location with interval resolution of symptoms. The purpose of this case report is to highlight the possibility of a ''recurrent'' soft tissue mass occurring for reasons other than a neoplasm. In the absence of a definitive biopsy diagnosis of tumor in patients who have undergone prior surgical procedures in that area, it may be more prudent to adopt a conservative surgical resection rather than a conventional radical resection as warranted by the dramatic clinical presentation mimicking a soft tissue sarcoma. (orig.)

2007-01-01

379

Recurrent pyogenic granuloma with satellitosis.  

UK PubMed Central (United Kingdom)

A 26-year-old woman was treated by curettage and cautery for a pyogenic granuloma on her left shoulder. This recurred 3 months later and was excised. After a further 5 months, she developed three vascular papules and one lobulated vascular lesion at the site. These ranged in size from 1-4 mm and the largest of these bled easily on minimal trauma. The authors treated the four vascular lesions with curettage and cautery and took a punch biopsy from an erythematous area in the scar. Histology was identical to the original lesion, confirming a diagnosis of recurrent pyogenic granuloma with satellitosis. One year later she had no evidence of recurrence of the lesions.

George SM; Gossain SR; Morrison IK; Coburn PR

2012-01-01

380

Pointwise-recurrent dendrite maps  

CERN Document Server

Let D be a dendrite and f:D-> D a continuous map. Denote by E(D) and B(D) the sets of endpoints and branch points of D respectively. We show that if E(D) is countable (resp. B(D) is discrete) then f is pointwise-recurrent if and only if f is pointwise periodic homeomorphism (resp. every pointin D\\E(D) is periodic).

Naghmouchi, Issam

2011-01-01

 
 
 
 
381

Recurrences in driven quantum systems  

CERN Document Server

We consider an initially bound quantum particle subject to an external time-dependent field. When the external field is large, the particle shows a tendency to repeatedly return to its initial state, irrespective of whether the frequency of the field is sufficient for escape from the well. These recurrences, which are absent in a classical calculation, arise from the system evolving primarily like a free particle in the external field.

Poduri, V; Patil, U; Poduri, V; Browne, D A; Patil, U

1994-01-01

382

Management and prevention of recurrent paratesticular liposarcoma.  

UK PubMed Central (United Kingdom)

Paratesticular liposarcoma is a rare entity. Compared to other genitourinary sarcoma, it is usually detected earlier and is easily resectable, resulting in an excellent prognosis. The recurrence of well-differentiated paratesticular liposarcoma after complete resection is extremely rare. Optimal management of the tumour recurrence includes complete re-excision and radiotherapy to the area of recurrence. Here, we describe a 48-year-old man with a recurrent left paratesticular well-differentiated liposarcoma, six years after its complete excision. Our discussion focused on the therapeutic strategy to prevent tumour recurrence. It is hoped that this case discussion can increase the awareness of this condition and assist in its management.

Song CH; Chai FY; Saukani MF; Singh H; Jiffre D

2013-07-01

383

Management and prevention of recurrent paratesticular liposarcoma.  

Science.gov (United States)

Paratesticular liposarcoma is a rare entity. Compared to other genitourinary sarcoma, it is usually detected earlier and is easily resectable, resulting in an excellent prognosis. The recurrence of well-differentiated paratesticular liposarcoma after complete resection is extremely rare. Optimal management of the tumour recurrence includes complete re-excision and radiotherapy to the area of recurrence. Here, we describe a 48-year-old man with a recurrent left paratesticular well-differentiated liposarcoma, six years after its complete excision. Our discussion focused on the therapeutic strategy to prevent tumour recurrence. It is hoped that this case discussion can increase the awareness of this condition and assist in its management. PMID:24044004

Song, Chun Hoong; Chai, Feng Yih; Saukani, Mohd Faizal Mohamad; Singh, Harbahajan; Jiffre, Din

2013-07-01

384

Review of 2 decades of aneurysm-recurrence literature, part 1: reducing recurrence after endovascular coiling.  

UK PubMed Central (United Kingdom)

SUMMARY: Angiographic recurrence following endovascular therapy is an indirect measure of the potential for hemorrhage. Because patients and physicians consider recurrence to be a suboptimal outcome with some chance of future hemorrhage, much effort has been expended to reduce the incidence of recurrence. The literature regarding aneurysm recurrence following endovascular therapy, spanning 2 decades, is extensive. We will review and summarize the effort to reduce recurrence following endovascular treatment of cerebral aneurysms.

Crobeddu E; Lanzino G; Kallmes DF; Cloft HJ

2013-02-01

385

Imetelstat Sodium in Treating Younger Patients With Recurrent or Refractory Brain Tumors  

Science.gov (United States)

Recurrent Childhood Anaplastic Astrocytoma; Recurrent Childhood Anaplastic Ependymoma; Recurrent Childhood Diffuse Astrocytoma; Recurrent Childhood Ependymoma; Recurrent Childhood Giant Cell Glioblastoma; Recurrent Childhood Glioblastoma; Recurrent Childhood Gliosarcoma; Recurrent Childhood Medulloblastoma; Recurrent Childhood Oligodendroglioma; Recurrent Childhood Supratentorial Primitive Neuroectodermal Tumor (PNET); Recurrent Childhood Brain Stem Glioma

2013-04-17

386

Erlotinib and Temozolomide in Treating Young Patients With Recurrent or Refractory Solid Tumors  

Science.gov (United States)

Previously Treated Childhood Rhabdomyosarcoma; Recurrent Childhood Brain Tumor; Recurrent Childhood Cerebellar Astrocytoma; Recurrent Childhood Cerebral Astrocytoma; Recurrent Childhood Ependymoma; Recurrent Childhood Malignant Germ Cell Tumor; Recurrent Childhood Medulloblastoma; Recurrent Childhood Rhabdomyosarcoma; Recurrent Childhood Soft Tissue Sarcoma; Recurrent Childhood Supratentorial Primitive Neuroectodermal Tumor; Recurrent Neuroblastoma; Recurrent Osteosarcoma

2013-06-04

387

Cure cycle evaluation for multilayer printed wiring boards  

Energy Technology Data Exchange (ETDEWEB)

The cure cycle for multilayer printed wiring boards (PWBs) made from general-puspore, fire-retardant epoxy/glass (GF) material has been evaluated for the optimum delamination resistance at soldering temperatures. The results that, for the epoxy resin system used to manufacture multilayer PWBs at Bendix Kansas City, a wide range of cure cycle variations has a minimal effect on delamination resistance.

Lula, J.W.

1980-06-01

388

Autologous human fibrin glue in multilayered amniotic membrane transplantation.  

UK PubMed Central (United Kingdom)

We describe and evaluate the efficiency of autologous human fibrin glue in multilayered amniotic membrane transplantation in a 66-year-old female with a persistent deep corneal ulcer and descemetocele. Defective epithelium of descemetocele was removed; separate and multilayered amniotic membranes were transplanted using autologous human fibrin glue. Finally a large amnion at the top was sutured on the cornea.

Ozcan AA

2008-01-01

389

Ultrahydrophobicity of Polydimethylsiloxanes-Based Multilayered Thin Films  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The formation of polydimethylsiloxanes (PDMSs)-based layer-by-layer multilayer ultrathin films on charged surfaces prepared from water and phosphate buffer solutions has been investigated. The multilayer films prepared under these conditions showed different surface roughness. Nanoscale islands and ...

Hongyan Gao; Karen Xiaohe Xu; Bin Chen; Li-Zhu Wu; Chen-Ho Tung; Hai-Feng Ji

390

Apparatus for the controlled deposition of multilayer films  

Digital Repository Infrastructure Vision for European Research (DRIVER)

A simple and stable apparatus for the controlled deposition of multilayer films in vacuo is described. In order to compare transmittance or reflectance of a multilayer film at two wavelength bands, the apparatus is equipped with a modulated light beam, two interference filters, two photo-tubes with ...

Sawaki, Tsukasa; Iwata, Minoru; Katsube, Shizuko; Hara, Kazuo

391

Magnetization process of Gd/Co multilayer films  

Energy Technology Data Exchange (ETDEWEB)

Gd/Co multilayer films were prepared by electron beam evaporation. The multilayer film of (110 Angstroms Gd/147 Angstroms Co) x 12 showed peculiar magnetization process around 150 K. This can be attributed to a transition of Gd spins from aligned to twisted states.

Tsunashima, S.; Ichikawa, T.; Nawate, M.; Uchiyama, S. (Nagoya Univ. (JP). Faculty of Engineering)

1988-12-01

392

MAGNETIZATION PROCESS OF Gd/Co MULTILAYER FILMS  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Gd/Co multilayer films were prepared by electron beam evaporation in a vacuum of ~ 10-7 Torr. The multilayer film of (110 Å Gd/147 Å Co) x 12 showed peculiar magnetization process around 150 K. This can be attributed to a transition of Gd spins from aligned to twisted states.

Tsunashima, S.; Ichikawa, T.; Nawate, M.; Uchiyama, S.

393

Optical multilayers as a tool for visualizing special relativity  

Energy Technology Data Exchange (ETDEWEB)

We re-elaborate on the recent basic result that the action of any multilayer is equivalent to a proper Lorentz transformation. As a consequence, we propose simple optical measurements that can serve as an analogue computer for simulating special relativity. Special attention is paid to the question of the Wigner rotation, showing that it can be easily observed in multilayers. (author)

Monzon, J.J.; Sanchez-Soto, L.L. [Departamento de Optica, Facultad de Ciencias Fisicas, Universidad Complutense, Madrid (Spain)

2001-01-01

394

Multi-layer laminate structure and manufacturing method  

Science.gov (United States)

The present invention is premised upon a multi-layer laminate structure and method of manufacture, more particularly to a method of constructing the multi-layer laminate structure utilizing a laminate frame and at least one energy activated flowable polymer.

Keenihan, James R. (Midland, MI); Cleereman, Robert J. (Midland, MI); Eurich, Gerald (Merrill, MI); Graham, Andrew T. (Midland, MI); Langmaid, Joe A. (Caro, MI)

2012-04-24

395

Multi-layer laminate structure and manufacturing method  

Energy Technology Data Exchange (ETDEWEB)

The present invention is premised upon a multi-layer laminate structure and method of manufacture, more particularly to a method of constructing the multi-layer laminate structure utilizing a laminate frame and at least one energy activated flowable polymer.

Keenihan, James R.; Cleereman, Robert J.; Eurich, Gerald; Graham, Andrew T.; Langmaid, Joe A.

2013-01-29

396

A MULTILAYER BIOCHEMICAL DRY DEPOSITION MODEL 1. MODEL FORMULATION  

Science.gov (United States)

A multilayer biochemical dry deposition model has been developed based on the NOAA Multilayer Model (MLM) to study gaseous exchanges between the soil, plants, and the atmosphere. Most of the parameterizations and submodels have been updated or replaced. The numerical integration ...

397

High-resolution x-ray analysis with multilayer gratings  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Periodic multilayers are nowadays widely used to perform x-ray analysis in the soft x-ray range (photon energy lower than 1 keV). However, they do not permit to obtain high-resolution spectra like natural or synthetic crystals. Thus, multilayers cannot resolve interferences between close x-ray lines...

Jonnard, Philippe; Le Guen, Karine; André, Jean-Michel

398

A refined model for characterizing x-ray multilayers  

Energy Technology Data Exchange (ETDEWEB)

The ability to quickly and accurately characterize arbitrary multilayers is very valuable for not only can we use the characterizations to predict the reflectivity of a multilayer for any soft x-ray wavelength, we also can generalize the results to apply to other multilayers of the same type. In addition, we can use the characterizations as a means of evaluating various sputtering environments and refining sputtering techniques to obtain better multilayers. In this report we have obtained improved characterizations for sample molybdenum-silicon and vanadium-silicon multilayers. However, we only examined five crystals overall, so the conclusions that we could draw about the structure of general multilayers is limited. Research involving many multilayers manufactured under the same sputtering conditions is clearly in order. In order to best understand multilayer structures it may be necessary to further refine our model, e.g., adopting a Gaussian form for the interface regions. With such improvements we can expect even better agreement with experimental values and continued concurrence with other characterization techniques. 18 refs., 30 figs., 7 tabs.

Oren, A.L.; Henke, B.L.

1987-12-01

399

Product recurrent properties, disjointness and weak disjointness  

CERN Multimedia

Let $\\F$ be a collection of subsets of $\\Z_+$ and $(X,T)$ be a dynamical system. $x\\in X$ is $\\F$-recurrent if for each neighborhood $U$ of $x$, $\\{n\\in\\Z_+:T^n x\\in U\\}\\in \\F$. $x$ is $\\F$-product recurrent if $(x,y)$ is recurrent for any $\\F$-recurrent point $y$ in any dynamical system $(Y,S)$. It is known that $x$ is $\\{infinite\\}$-product recurrent if and only if it is minimal and distal. In this paper it is proved that the closure of a $\\{syndetic\\}$-product recurrent point (i.e. weakly product recurrent point) has a dense minimal points; and a $\\{piecewise syndetic\\}$-product recurrent point is minimal. Moreover, it is observed that if $(X,T)$ is disjoint from all minimal systems, then each transitive point of $(X,T)$ is weakly product recurrent. Results on product recurrence when the closure of an $\\F$-recurrent point has zero entropy are obtained. Several results on disjointness are given, and results on weak disjointness are described when considering disjointness.

Dong, Pandeng; Ye, Xiangdong

2009-01-01

400

Endoscopic endonasal multilayer repair of traumatic ethmoidal roof cerebrospinal fluid rhinorrhea in children.  

UK PubMed Central (United Kingdom)

OBJECTIVE: Pediatric traumatic cerebrospinal fluid (CSF) leak is a challenging problem in diagnosis and management. Posttraumatic leaks frequently present by intermittent rhinorrhea or by recurrent attacks of meningitis, which can be the only presenting symptom. The objective of this study is to present our experience in management of pediatric traumatic ethmoidal roof CSF leaks using a multilayer repair technique via an endoscopic approach. METHODS: Ten pediatric patients (aged 4-14 years, six males and four females) presenting with posttraumatic ethmoidal roof CSF rhinorrhea were operated upon between January 2007 and December 2010, using an endoscopic endonasal multilayer repair technique. Preoperative radiological evaluation included both multidetector computed tomography (MDCT) with ultra-thin 1mm cuts, and magnetic resonance imaging (MRI) high resolution coronal T2-weighted sequence. Intraoperatively, the GE InstaTrak™ 3500 electromagnetic navigation system was used in all cases. Postoperative follow-up was done clinically by regular endoscopic examinations and radiologically by MRI assessment using the same preoperative protocol. RESULTS: Clinically all patients presented with unilateral intermittent watery rhinorrhea with periods ranging from 5 to 24 months before operation. Seven cases had a history of recurrent meningitis. Defects were confined to ethmoidal roof in all 10 cases (right side in seven and left side in three), and ranged in size from 2 to 7 mm(2) (mean 3.9 ± 1.5 mm(2)). Two cases had more than one defect on the same side. All defects were identified preoperatively using our radiological protocol. One case was associated with a meningocele with no brain herniation and another case was associated with a small meningoencephalocele. Mean postoperative hospitalization was 6 days (range 4-8 days). None of our patients developed any intra or postoperative complications or required revision surgery with a 100% success rate after a mean follow-up duration of 29.4 ± 14.4 months (range 12-52 months). CONCLUSIONS: Pediatric posttraumatic CSF leaks involving the ethmoidal roof can be successfully managed via the endonasal endoscopic route using a multilayer repair technique, thus limiting complications associated with external approaches. Preoperative imaging including MDCT and high resolution MRI is of paramount importance for detecting the defect site and for planning surgery.

Ibrahim AA; Magdy EA; Eid M

2012-04-01

 
 
 
 
401

Simulation of X-ray scattering from multilayers  

International Nuclear Information System (INIS)

This paper describes basic methods for the simulation of X-ray scattering from ideal and non-ideal multilayers. In the 1 D model the kinematical and dynamical calculation is made with several kinds of disturbances of the ideal structure of the multilayers. We shall discuss the influence of surface roughness, interdiffusion between layers and fluctuation of thickness in the multilayer. In the second part some ideas are given to get non-specular scattering simulations of disturbed multilayer structures in a 2 D model. Although this is a well-known subject and has been treated several times in the last years, it is really fruitful to do the basic steps for this topic, because it can give you a deep insight into the physics of a travelling wave inside a multilayer. (author) 26 figs., 1 tab., 4 refs

1995-01-01

402

Synthesis and Characterization of Multilayered Diamond Coatings for Biomedical Implants  

Directory of Open Access Journals (Sweden)

Full Text Available With incredible hardness and excellent wear-resistance, nanocrystalline diamond (NCD) coatings are gaining interest in the biomedical community as articulating surfaces of structural implant devices. The focus of this study was to deposit multilayered diamond coatings of alternating NCD and microcrystalline diamond (MCD) layers on Ti-6Al-4V alloy surfaces using microwave plasma chemical vapor deposition (MPCVD) and validate the multilayer coating’s effect on toughness and adhesion. Multilayer samples were designed with varying NCD to MCD thickness ratios and layer numbers. The surface morphology and structural characteristics of the coatings were studied with X-ray diffraction (XRD), Raman spectroscopy, and atomic force microscopy (AFM). Coating adhesion was assessed by Rockwell indentation and progressive load scratch adhesion tests. Multilayered coatings shown to exhibit the greatest adhesion, comparable to single-layered NCD coatings, were the multilayer samples having the lowest average grain sizes and the highest titanium carbide to diamond ratios.

Leigh Booth; Shane A. Catledge; Dustin Nolen; Raymond G. Thompson; Yogesh K. Vohra

2011-01-01

403

Fracture mechanics parameters of multilayer pipes  

Directory of Open Access Journals (Sweden)

Full Text Available Multilayer pipes consisting of different materials are frequently used in praxis because of partial improvement of the properties of pipe systems. To estimate lifetime of these pipes the basic fracture parameters have to be determined. In this work finite element calculations are applied in order to estimate the stress intensity factor K and T-stress values for a new type of non-homogenous C-shape specimen. The application of calculated K and T values to laboratory estimation of fracture toughness and its transferability to real pipe system is discussed.

Šestáková L.; Náhlík L.; Huta? P.; Knésl Z.

2007-01-01

404

Magnetic anisotropy of Ni/Cr multilayers  

Energy Technology Data Exchange (ETDEWEB)

The magnetic anisotropy of Ni/Cr multilayers has been investigated by using vibrating sample magnetometer (VSM) and ferromagnetic resonance techniques (FMR). The FMR spectra are obtained as a function of the orientation of the applied magnetic field from in-plane to out-of-plane. The results are fitted theoretically to determine the magnetic anisotropy. From VSM and FMR, a positive value for Ni/Cr interface anisotropy is obtained, which favours a perpendicular easy axis. The possible mechanism for the perpendicular anisotropy has been discussed and it may be attributed to the magnetostriction, caused by intrinsic stress due to lattice mismatch. (orig.). With 005 figs., 001 tabs.

Kang, S. [Nanjing Univ. (China). Nat. Lab. of Solid State Microstructures]|[Nanjing Univ. (China). Center for Adv. Studies in Sci. and Technol.; Wang, H. [Nanjing Univ. (China). Nat. Lab. of Solid State Microstructures]|[Nanjing Univ. (China). Center for Adv. Studies in Sci. and Technol.; Lin, Z. [Nanjing Univ. (China). Nat. Lab. of Solid State Microstructures]|[Nanjing Univ. (China). Center for Adv. Studies in Sci. and Technol.; Jin, G. [Nanjing Univ. (China). Nat. Lab. of Solid State Microstructures]|[Nanjing Univ. (China). Center for Adv. Studies in Sci. and Technol.; Hu, A. [Nanjing Univ. (China). Nat. Lab. of Solid State Microstructures]|[Nanjing Univ. (China). Center for Adv. Studies in Sci. and Technol.; Jiang, S. [Nanjing Univ. (China). Nat. Lab. of Solid State Microstructures]|[Nanjing Univ. (China). Center for Adv. Studies in Sci. and Technol.; Feng, J. [Wuhan Institute of Physics, Academia Sinica, Wuhan 430071 (China); Xia, H. [Beijing General Institute of Non-ferrous Metals, Beijing 100080 (China)

1997-06-01

405

Photopatterning of multilayer n-alkylsilane films.  

Science.gov (United States)

Surface photopatterning of organosilane self-assembled monolayers (SAM) has received increasing attention since its introduction 20 years ago. Herein we report for the first time a cost-efficient soft photopatterning technique affording amplified 3D multilayer structures. The essential chemistry relies on a spatially controlled photoacid-catalyzed hydrolysis and polycondensation of n-alkyltrimethoxysilane precursors (n-C(12)H(25)Si(OCH(3))(3),). Amphiphilic siloxane species are photogenerated locally and are able to self-assemble spontaneously into a long-range-ordered lamellar mesostructure. PMID:22515368

Ni, Lingli; Chemtob, Abraham; Croutxé-Barghorn, Céline; Brendlé, Jocelyne; Vidal, Loïc; Rigolet, Séverinne

2012-04-23

406

Photopatterning of multilayer n-alkylsilane films.  

UK PubMed Central (United Kingdom)

Surface photopatterning of organosilane self-assembled monolayers (SAM) has received increasing attention since its introduction 20 years ago. Herein we report for the first time a cost-efficient soft photopatterning technique affording amplified 3D multilayer structures. The essential chemistry relies on a spatially controlled photoacid-catalyzed hydrolysis and polycondensation of n-alkyltrimethoxysilane precursors (n-C(12)H(25)Si(OCH(3))(3),). Amphiphilic siloxane species are photogenerated locally and are able to self-assemble spontaneously into a long-range-ordered lamellar mesostructure.

Ni L; Chemtob A; Croutxé-Barghorn C; Brendlé J; Vidal L; Rigolet S

2012-05-01

407

Interdiffused Multilayer Processing (IMP) in alloy growth  

Science.gov (United States)

The Interdiffused Multilayer Processing (IMP) technique has been developed as a way of growing uniform layers of cadmium mercury telluride (CMT). The principle of the technique is discussed in the context of an interdiffusion coefficient so as to assess the potential applicability of the technique to the growth of other II-VI or III-V alloys. The development of IMP for the growth of CMT layers, together with the properties of the layers and their suitability for use in the fabrication of IR detectors, is reviewed.

Mullin, J. B.; Giess, J.; Irvine, S. J. C.; Gough, J. S.; Royle, A.

408

Magnetic properties of Fe/Tb multilayers  

Energy Technology Data Exchange (ETDEWEB)

Multilayered Fe/Tb samples were prepared under ultrahigh vacuum conditions ({ital p}{lt}10{sup {minus}9} mbar) on kapton substrates. A total of four different samples were prepared. Three of them correspond to a series where the Tb thickness is constant at 26 A and Fe varies from 10 to 30 A. The fourth one is the first of a new series where Tb is 7 A thick and Fe 40 A. The samples were investigated by means of SQUID magnetometry and Moessbauer spectroscopy. All samples show perpendicular magnetic anisotropy at low temperature (4.2 K), but only two of them are able to show it at room temperature.

Badia, F.; Badry, M.A.; Zhang, X.X.; Tejada, J. (Dep. Fisica Fonamental, Universitat de Barcelona, Diagonal, 647, E-08028 Barcelona (Spain)); Brand, R.A.; Scholz, B.; Keune, W. (Laboratorium fuer Angewandte Physik, 4100 Duisburg (Germany))

1991-11-15

409

Magnetic properties of Fe/Tb multilayers  

International Nuclear Information System (INIS)

Multilayered Fe/Tb samples were prepared under ultrahigh vacuum conditions (p-9 mbar) on kapton substrates. A total of four different samples were prepared. Three of them correspond to a series where the Tb thickness is constant at 26 A and Fe varies from 10 to 30 A. The fourth one is the first of a new series where Tb is 7 A thick and Fe 40 A. The samples were investigated by means of SQUID magnetometry and Moessbauer spectroscopy. All samples show perpendicular magnetic anisotropy at low temperature (4.2 K), but only two of them are able to show it at room temperature.

1991-01-01

410

Magnetic properties of Dy/Zr multilayers  

International Nuclear Information System (INIS)

[en] [Dy(xA)/Zr(30A)]n superlattices (x ? 30), were evaporated under ultra-high vacuum on Si(100) substrates. Magnetization measurements indicate that the antiferromagnetic transition occurring at 178K in bulk Dy is suppressed in the multilayers. This phenomenon is attributed to magnetoelastic effects induced by strains at Zr/Dy interfaces. A perpendicular magnetic anisotropy takes place for x ? 15. However, the magnetic anisotropy is found to depend markedly on the technique used for Dy deposition. (author). 11 refs., 4 figs

1992-01-01

411

Multilayer shallow layer trauma special hydrophilic dressing  

UK PubMed Central (United Kingdom)

The invention relates to a multilayered hydrophilic wound dressing for superficial wounds, which is a hydrophilic adhesive film layer formed by applying a composite coating made of medical-grade animal glues, medical-grade plant gums, hemostatic ingredients, bactericide diluent and plant fiber additives on a dressing material contacting a wound contact surface. The outer layer of the wound dressing is a dressing forming film layer for preventing the shrinkage of the wound dressing, the dressing forming film layer can be removed during application, and the wound dressing is uniformly perforated to drain excessive exudates or blood. The inventive wound dressing has improved adhesiveness and can well control the superficial wound infection.

CHANGZHONG ZHOU; JIARU SHI

412

Static and dynamic properties of Fibonacci multilayers  

Science.gov (United States)

We theoretically investigate static and dynamic properties of quasiperiodic magnetic multilayers. We considered identical ferromagnetic layers separated by non-magnetic spacers with two different thicknesses chosen based on the Fibonacci sequence. Using parameters for Fe/Cr, the minimum energy was determined and the equilibrium magnetization directions found were used to calculate magnetoresistance curves. Regarding dynamic behavior, ferromagnetic resonance (FMR) curves were calculated using an approximation known from the literature. Our numerical results illustrate the effects of quasiperiodicity on the static and dynamic properties of these structures.

Machado, L. D.; Bezerra, C. G.; Correa, M. A.; Chesman, C.; Pearson, J. E.; Hoffmann, A.

2013-05-01

413

Manufacture and analysis of multilayer woven preforms  

Energy Technology Data Exchange (ETDEWEB)

Multilayer woven preforms were manufactured from high-tenacity, continuous multifilament polyester yarn and HTA carbon yarn. Orthogonal fiber architectures were constructed with a variety of binder thread configurations and yarn densities. The effect of the binder thread arrangement upon the as-woven preform architecture was examined. The preforms were then consolidated using liquid moulding techniques and the effect of the consolidation pressure upon the fiber architecture was investigated. Modeling of the preform architecture in its as-woven state is progressing and preliminary results are presented in this paper.

Bannister, M.K.; Herszberg, I.; Coman, F.; Raper, H.; Curiskis, J. [Royal Melbourne Institute of Technology (Australia)

1994-12-31

414

Optics and multilayer coatings for EUVL systems  

Energy Technology Data Exchange (ETDEWEB)

EUV lithography (EUVL) employs illumination wavelengths around 13.5 nm, and in many aspects it is considered an extension of optical lithography, which is used for the high-volume manufacturing (HVM) of today's microprocessors. The EUV wavelength of illumination dictates the use of reflective optical elements (mirrors) as opposed to the refractive lenses used in conventional lithographic systems. Thus, EUVL tools are based on all-reflective concepts: they use multilayer (ML) coated optics for their illumination and projection systems, and they have a ML-coated reflective mask.

Soufli, R; Bajt, S; Hudyma, R M; Taylor, J S

2008-03-21

415

Magnetic pinning in superconductor-ferromagnet multilayers  

Energy Technology Data Exchange (ETDEWEB)

We argue that superconductor/ferromagnet multilayers of nanoscale period should exhibit strong pinning of vortices by the magnetic domain structure in magnetic fields below the coercive field when ferromagnetic layers exhibit strong perpendicular magnetic anisotropy. The estimated maximum magnetic pinning energy for single vortex in such a system is about 100 times larger than the pinning energy by columnar defects. This pinning energy may provide critical currents as high as 10{sup 6}-10{sup 7} A/cm{sup 2} at high temperatures (but not very close to T{sub c}) at least in magnetic fields below 0.1 T. (c) 2000 American Institute of Physics.

Bulaevskii, L. N. [Department of Physics and Astronomy, CUNY Lehman College 250 Bedford Park Boulevard West, Bronx, New York 10468-1589 (United States); Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Chudnovsky, E. M. [Department of Physics and Astronomy, CUNY Lehman College, 250 Bedford Park Boulevard West, Bronx, New York 10468-1589 (United States); Maley, M. P. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

2000-05-01

416

Multimedia Traffic Routing in Multilayer WDM Networks  

CERN Document Server

The advent of real-time multimedia services over the Internet has stimulated new technologies for expanding the information carrying capacity of optical network backbones. Multilayer wavelength division multiplexing (WDM) packet switching is an emerging technology for increasing the bandwidth of optical networks. Two algorithms for the routing of the multimedia traffic flows were applied: (i) Capacitated Shortest Path First (CSPF) routing, which minimizes the distance of each flow linking the given source and destination nodes and satisfying capacity constraints; and (ii) Flow Deviation Algorithm (FDA) routing, which minimizes the network?wide average packet delay.

Amphawan, Angela; Hasan, Hassanuddin

2012-01-01

417

Recurrence of leiomyomata after laparoscopic myomectomy.  

UK PubMed Central (United Kingdom)

STUDY OBJECTIVE: To assess recurrence of leiomyomata after laparoscopic myomectomy (LM) and evaluate predictive factors of recurrence. DESIGN: Observational study (Canadian Task Force classification II-2). SETTING: University hospital. PATIENTS: One hundred ninety-six women. INTERVENTION: Laparoscopic myomectomy with mean follow-up of 47 months. MEASUREMENTS AND RESULTS: Myoma recurrence included recurrence of initial symptomatology before LM, recurrence at clinical examination, and appearance of a myoma 2 cm or larger on ultrasound examination. Recurrence was observed in 45 patients (22.9%). The mean time before recurrence was 42 months (range 4-95 mo). Eight women (4.08%) required reoperation. The cumulative recurrence risk was 12.7% at 2 years and 16.7% at 5 years. Predictive factors for recurrence were number of myomas and nulliparity. CONCLUSION: According to our results, the cumulative rate of myoma recurrence within 5 years appears greater after LM than after laparotomy. However, this should not lead us to reject laparoscopy, which has many advantages compared with laparotomy, in particular its low morbidity.

Doridot V; Dubuisson JB; Chapron C; Fauconnier A; Babaki-Fard K

2001-11-01

418

Superconductivity and vortex properties in various multilayers  

International Nuclear Information System (INIS)

In this thesis three qualitatively different type of superconducting multilayers are studied. We discuss the vortex lattice structure in Nb/NbZr multilayers, a system where both type of constituting layers are superconducting. At certain temperatures and for parallel fields close to Hc2parallel, the Nb/NbZr system has a strongly modulated order parameter, and in this aspect resembles the high-Tc materials. By lowering the field the modulation decreases, having important consequences for the vortex lattice structure. By studying the transport critical currents we show that in the case of strong modulation the vortex lattice has a kinked structure, but at weaker modulations the vortices are straight, and the change in modulation actually results in a vortex lattice transition. Our study confirms the picture of the existence of kinked vortex lattices, but it is rather surprising that these kinked structures can exist in a system which in itself is not at all that anisotropic. It indicates the relevance of other parameters governing the vortex lattice structure. (orig.)

1994-01-01

419

Deformation mechanism maps for polycrystalline metallic multilayers  

Energy Technology Data Exchange (ETDEWEB)

Metallic multilayers represent an ideal vehicle for the exploration of length scales in plasticity. They also provide the opportunity to synthesize materials with controlled interfaces and structures for the production of materials close to the theoretical strength. In the present investigation, the authors present a simple analysis that allows us to obtain limiting values of microstructural scales at which these different mechanisms operate. They present the results in the form of two-dimensional maps of layer thickness and grain size ranges over which different deformation mechanisms operate. These maps are intended to be guidelines for interpreting the scale-dependent strengthening or softening mechanisms in multilayers, in the same manner as Ashby's deformation mechanism maps for temperature and stress dependent deformation behavior of metals. An attempt to extend Ashby's deformation mechanism maps to Al thin films by Frost revealed that the predicted strain rates were several orders of magnitude higher than the observed rates due to the higher flow stresses of thin films. Hence, more work is needed to incorporate the fundamental differences in the deformation behavior of thin films and bulk polycrystals to map the mechanisms as a function of stress, temperature and microstructural scale. In this article the authors only consider changes in deformation mechanisms with decreasing length scales at constant temperature and strain rates.

Misra, A.; Verdier, M.; Kung, H.; Embury, J.D.; Hirth, J.P.

1999-10-08

420

Finite element analysis of multilayer coextrusion.  

Energy Technology Data Exchange (ETDEWEB)

Multilayer coextrusion has become a popular commercial process for producing complex polymeric products from soda bottles to reflective coatings. A numerical model of a multilayer coextrusion process is developed based on a finite element discretization and two different free-surface methods, an arbitrary-Lagrangian-Eulerian (ALE) moving mesh implementation and an Eulerian level set method, to understand the moving boundary problem associated with the polymer-polymer interface. The goal of this work is to have a numerical capability suitable for optimizing and troubleshooting the coextrusion process, circumventing flow instabilities such as ribbing and barring, and reducing variability in layer thickness. Though these instabilities can be both viscous and elastic in nature, for this work a generalized Newtonian description of the fluid is used. Models of varying degrees of complexity are investigated including stability analysis and direct three-dimensional finite element free surface approaches. The results of this work show how critical modeling can be to reduce build test cycles, improve material choices, and guide mold design.

Hopkins, Matthew Morgan; Schunk, Peter Randall; Baer, Thomas A. (Proctor & Gamble Company, West Chester, OH); Mrozek, Randy A. (Army Research Laboratory, Adelphi, MD); Lenhart, Joseph Ludlow (Army Research Laboratory, Adelphi, MD); Rao, Rekha Ranjana; Collins, Robert (Oak Ridge National Laboratory); Mondy, Lisa Ann

2011-09-01

 
 
 
 
421

Stereotactic radiosurgery for recurrent ependymoma.  

UK PubMed Central (United Kingdom)

BACKGROUND: Patients with recurrent intracranial ependymomas were evaluated to assess local control, overall survival, and complications from stereotactic radiosurgery (SRS). METHODS: Twelve patients (with a total of 17 tumors) with recurrent ependymoma underwent SRS. Local failure was defined as tumor progression within the prescription isodose volume, and marginal failure was defined as tumor progression adjacent to the SRS prescription isodose volume. Tumor progression away from the prescription volume was considered distant failure. Eleven of the 12 patients had undergone previous resection and external beam radiation therapy (46-56 Grays [Gy]; median, 54 Gy) before radiosurgery, and 1 patient had failure after complete resection alone. Age at SRS ranged from 5-56 years (median, 29 years). Three patients were female. The marginal tumor dose was 12-24 Gy (median, 18 Gy). One to 14 isocenters (median, 4 isocenters) were utilized to irradiate volumes of 0.3-15.5 cm(3) (median, 3.2 cm(3)). RESULTS: The duration of follow-up ranged from 2.5-60 months (median, 22.5 months). The median overall survival after SRS was 3.4 years (range, 1.4-5 years). In-field local control was achieved in 14 of the 17 tumor sites and estimated 3-year local control was 68%. There were two in-field failures and one marginal failure. Distant failure occurred in two patients. Two patients developed treatment-related complications after SRS. CONCLUSIONS: SRS provides good local tumor control for patients with recurrent intracranial ependymoma and may have a favorable impact on survival. SRS should be evaluated more extensively in the initial treatment of patients with ependymoma to minimize local failure after surgical management.

Stafford SL; Pollock BE; Foote RL; Gorman DA; Nelson DF; Schomberg PJ

2000-02-01

422

The Kernelized Stochastic Batch Perceptron  

CERN Document Server

We present a novel approach for training kernel Support Vector Machines, establish learning runtime guarantees for our method that are better then those of any other known kernelized SVM optimization approach, and show that our method works well in practice compared to existing alternatives.

Cotter, Andrew; Srebro, Nathan

2012-01-01

423

Recurrent Pericarditis in Myhre Syndrome.  

UK PubMed Central (United Kingdom)

Myhre syndrome is a rare disorder characterized by pre- and postnatal short stature, brachydactyly, facial dysmorphism (short palpebral fissures, maxillary hypoplasia, prognathism and short philtrum), thick skin, muscular-appearing body build, decreased joint mobility, mixed hearing loss, and cleft lip and palate. Other clinical features include skeletal dysplasia, developmental delay with intellectual disability and/or behavioral disturbance, cardiac defects, cryptorchidism, and bone anomalies. The disease is caused by recently identified SMAD4 mutations. Here we describe a 7-year-old boy with a molecularly proven Myhre syndrome who presented life-threatening recurrent pericarditis and systemic inflammatory symptoms that required treatment with steroid and recombinant interleukin-1 receptor antagonist.

Picco P; Naselli A; Pala G; Marsciani A; Buoncompagni A; Martini A

2013-03-01

424

Recurrent pericarditis in Myhre syndrome.  

UK PubMed Central (United Kingdom)

Myhre syndrome is a rare disorder characterized by pre- and postnatal short stature, brachydactyly, facial dysmorphism (short palpebral fissures, maxillary hypoplasia, prognathism and short philtrum), thick skin, muscular-appearing body build, decreased joint mobility, mixed hearing loss, and cleft lip and palate. Other clinical features include skeletal dysplasia, developmental delay with intellectual disability and/or behavioral disturbance, cardiac defects, cryptorchidism, and bone anomalies. The disease is caused by recently identified SMAD4 mutations. Here we describe a 7-year-old boy with a molecularly proven Myhre syndrome who presented life-threatening recurrent pericarditis and systemic inflammatory symptoms that required treatment with steroid and recombinant interleukin-1 receptor antagonist.

Picco P; Naselli A; Pala G; Marsciani A; Buoncompagni A; Martini A

2013-05-01

425

Recurrent neurofibroma of the orbit.  

UK PubMed Central (United Kingdom)

A 55-year-old male patient presented with gradual progressive outward and downward deviation of right eye since last two years, with history of a similar complaint 10 years ago when he was diagnosed as having neurofibroma of the orbit. Computed Tomography imaging revealed a large, multilobulated, heterogeneous, soft tissue density mass lesion in the retro bulbar region on the medial side of right orbit suggestive of a neurofibroma. Excision and histopathology confirmed it to be a recurrence of neurofibroma of the orbit.

Misra S; Gogri P; Misra N; Bhandari A

2013-01-01

426

Recurrent colonic volvulus in children.  

UK PubMed Central (United Kingdom)

Recurrent intestinal obstruction caused by colonic volvulus is a rare cause of intestinal obstruction in children. Because the condition is self rectifying at times, the diagnosis can be missed or delayed. The authors present two patients, one with sigmoid volvulus and the other with sigmoid and cecal volvulus, and discuss the diagnosis and management of this condition in children. In view of the recurring nature of this condition, the authors believe that nonoperative treatment of this condition in children has no place beyond the emergency situation and that the definitive treatment should always be surgical.

Ismail A

1997-12-01

427

Recurrences in driven quantum systems  

Science.gov (United States)

We calculate the recombination probability for an atom interferometric experiment in which the beams interfere after one of them has been exposed to an intense laser. We choose a model one-dimensional atomic potential and find that if the intensity of the laser is large, there are recurrences in the recombination probability as a function of time, irrespective of the frequency of excitation. This implies that the particles exposed to the laser have a large amplitude to be in the localized initial state in spite of having sufficient energy to escape from the binding potential.

Poduri, V.; Browne, D. A.; Patil, U.

1995-06-01

428

Folding in power-law viscous multi-layers.  

UK PubMed Central (United Kingdom)

We study high-amplitude folding in layered rocks with two-dimensional numerical simulations. We employ the finite-element method to model shortening of an incompressible multi-layer with power-law viscous rheology. The Lagrangian numerical mesh is deformed and re-meshed to accurately follow the layer interfaces. Three settings are considered: (i) pure shearing of a confined multi-layer, (ii) simple shearing of a multi-layer above a detachment, and (iii) slump folding owing to gravity sliding. In our pure shear simulations, finite-amplitude folds always develop despite confinement and thin weak interlayers. The fold shapes can be significantly irregular, resulting from initial geometrical heterogeneities that are perturbations of the layer interfaces and differences in layer thickness. The bulk normal viscosity of the multi-layer decreases significantly with progressive folding. This structural softening decreases the bulk normal viscosities by a factor of 2-20. For simple shear, the multi-layer does not develop asymmetric fold shapes significantly. Fold axial planes in the multi-layer are mostly curved and not parallel. For slump folding, fold shapes can be significantly asymmetric exhibiting strongly curved fold axial planes and overturned fold limbs. The rheology of the competent layers has a major impact on the fold shapes for gravity-driven multi-layer folding.

Schmalholz SM; Schmid DW

2012-04-01

429

Interdiffusion and structural relaxation in Mo/Si multilayer films  

Energy Technology Data Exchange (ETDEWEB)

Interdiffusion and structural change on annealing of sputter-deposited Mo/Si and Mo(N)/Si(N) multilayer thin films have been investigated over the temperature range from 674 to 1027 K. X-ray diffractometry shows that in the as-deposited Mo/Si multilayers the Mo is bcc with the stacking of (110) plane parallel to the substrate, and the Si is amorphous, while in the as-deposited Mo(N)/Si(N) multilayers, both Mo and Si nitrides are amorphous. The interdiffusivities have been determined from the decay rate of satellite peak intensity around (000). The activation energies for the interdiffusion in Mo/Si and Mo(N)/Si(N) multilayers are 105 +- 5 and 351 +- 88 kJ mol/sup -1/, respectively. A drastic decrease in the satellite peak intensity on annealing is observed in the Mo/Si multilayer films, which is interpreted to be due to interdiffusion and structural relaxation. On the other hand, a remarkable increase in the satellite intensity is found for the nitride multilayer films, which is explained by crystallization into ..beta..-Mo/sub 2/N/..cap alpha..-Si/sub 3/N/sub 4/. The modulation wavelength decreases by 8%--12% after anneal. The decrease in the thickness of annealed Mo/Si multilayer films is also found by a depth profilometer.

Nakajima, H.; Fujimori, H.; Koiwa, M.

1988-02-15

430

Interdiffusion and structural relaxation in Mo/Si multilayer films  

International Nuclear Information System (INIS)

[en] Interdiffusion and structural change on annealing of sputter-deposited Mo/Si and Mo(N)/Si(N) multilayer thin films have been investigated over the temperature range from 674 to 1027 K. X-ray diffractometry shows that in the as-deposited Mo/Si multilayers the Mo is bcc with the stacking of (110) plane parallel to the substrate, and the Si is amorphous, while in the as-deposited Mo(N)/Si(N) multilayers, both Mo and Si nitrides are amorphous. The interdiffusivities have been determined from the decay rate of satellite peak intensity around (000). The activation energies for the interdiffusion in Mo/Si and Mo(N)/Si(N) multilayers are 105 +- 5 and 351 +- 88 kJ mol-1, respectively. A drastic decrease in the satellite peak intensity on annealing is observed in the Mo/Si multilayer films, which is interpreted to be due to interdiffusion and structural relaxation. On the other hand, a remarkable increase in the satellite intensity is found for the nitride multilayer films, which is explained by crystallization into ?-Mo2N/?-Si3N4. The modulation wavelength decreases by 8%--12% after anneal. The decrease in the thickness of annealed Mo/Si multilayer films is also found by a depth profilometer

1988-02-15

431

Advances in polyelectrolyte multilayer nanofilms as tunable drug delivery systems  

Directory of Open Access Journals (Sweden)

Full Text Available Bingbing Jiang1, John B Barnett2,3, Bingyun Li1,4,5#1Biomaterials, Bioengineering and Nanotechnology Laboratory, Department of Orthopaedics, School of Medicine, 2Department of Microbiology, Immunology, and Cell Biology, 3Center for Immunopathology and Microbial Pathogenesis, School of Medicine, 5Department of Chemical Engineering, College of Engineering and Mineral Resources, West Virginia University, Morgantown, WV, USA; 4WVNano Initiative, Morgantown, WV, USA; #Aided by a grant from Osteosynthesis and Trauma Care (OTC) FoundationAbstract: There has been considerable interest in polyelectrolyte multilayer nanofilms, which have a variety of applications ranging from optical and electrochemical materials to biomedical devices. Polyelectrolyte multilayer nanofilms are constructed from aqueous solutions using electrostatic layer-by-layer self-assembly of oppositely-charged polyelectrolytes on a solid substrate. Multifunctional polyelectrolyte multilayer nanofilms have been studied using charged dyes, metal and inorganic nanoparticles, DNA, proteins, and viruses. In the past few years, there has been increasing attention to developing polyelectrolyte multilayer nanofilms as drug delivery vehicles. In this mini-review, we present recent developments in polyelectrolyte multilayer nanofilms with tunable drug delivery properties, with particular emphasis on the strategies in tuning the loading and release of drugs in polyelectrolyte multilayer nanofilms as well as their applications.Keywords: nanofilm, polyelectrolyte multilayer, drug delivery, electrostatic layer-by-layer self-assembly, biomedical device, surface modification

Bingbing Jiang; John B Barnett; Bingyun Li

2009-01-01

432

Cytokines in recurrent pregnancy loss.  

UK PubMed Central (United Kingdom)

BACKGROUND: Recurrent pregnancy loss (RPL) is defined as the occurrence of three or more consecutive miscarriages prior to 20 weeks gestation. Exaggerated maternal immune response to fetal antigens has been proposed to be one of the mechanisms underlying recurrent pregnancy loss. METHOD: A comprehensive literature search was conducted from the websites of the National Library of Medicine (http://www.ncbl.nlm.nih.gov) and Pubmed Central, the US National Library of Medicine's digital archive of life sciences literature (http://www.pubmedcentral.nih.gov/). The data was assessed from books and journals that published relevant articles in this field. RESULT: In normal pregnancy, tolerance of the genetically incompatible fetus by the maternal immune system depends on the interactions of an array of cytokines secreted by maternal and fetal cells at the site of implantation. Earlier research indicated that altered immunity in RPL is dominated by the Th1/Th2 hypothesis, which proposed that the fetus escapes maternal-derived T-cell responses through skewing the Th0 differentiation toward Th2 pathway which dampens pro-inflammatory Th1-type immunity. Recent studies indicate the role of proinflammatory Th17 cells and immunoregulatory Treg cells in RPL in addition to Th1/Th2 interactions. CONCLUSION: Cytokines form a complex regulatory network which maintains homeostasis between the fetal unit and the maternal immune system. If this delicate balance is adversely affected, immunoregulatory mechanisms may be insufficient to restore homeostasis and this may lead to pregnancy failure.

Saini V; Arora S; Yadav A; Bhattacharjee J

2011-04-01

433

Recurrent vaginal discharge in children.  

UK PubMed Central (United Kingdom)

BACKGROUND: Childhood vaginal discharge remains a frequent reason for referral from primary to secondary care. The Pediatric and Adolescent Gynecology (PAG) service at Kettering General Hospital was established in 1993 and provides a specialized service that meets the needs of children with gynaecological conditions. AIM: To investigate recurrent vaginal discharge noting symptomatology, defining pathogens, common and rarer causes, exploring management regimes, and any changes in practice over time. METHOD: Retrospective review spanning 15 years identifying prepubertal children attending the outpatient PAG clinic with recurrent vaginal discharge. We reviewed the medical notes individually. RESULTS: 110 patients were identified; 85% were referred from primary care. The age distribution was bimodal at four and eight years. Thirty-five percent of our patients were discharged after the initial consultation. The commonest cause of discharge was vulvovaginitis (82%). Other important causes included suspected sexual abuse (5%), foreign body (3%), labial adhesions (3%), vaginal agenesis (2%). 35% of patients were admitted for vaginoscopy. CONCLUSION: Vaginal discharge is the most common gynecological symptom in prepubertal girls and can cause repeated clinical episodes. Vulvovaginitis is the most common cause and often responds to simple hygiene measures. Awareness of the less common causes of vaginal discharge is essential.

McGreal S; Wood P

2013-08-01

434

Improved Reflectance and Stability of Mo/Si Multilayers  

Energy Technology Data Exchange (ETDEWEB)

Commercial EUV lithographic systems require multilayers with higher reflectance and better stability then that published to date. Interface-engineered Mo/Si multilayers with 70% reflectance at 13.5 nm wavelength (peak width of 0.545 nm) and 71% at 12.7 nm wavelength (peak width of 0.49 nm) were developed. These results were achieved with 50 bilayers. These new multilayers consist of Mo and Si layers separated by thin boron carbide layers. Depositing boron carbide on interfaces leads to reduction in silicide formation on the Mo-on-Si interfaces. Bilayer contraction is reduced by 30% implying that there is less intermixing of Mo and Si to form silicide. As a result the Mo-on-Si interfaces are sharper in interface-engineered multilayers than in standard Mo/Si multilayers. The optimum boron carbide thicknesses have been determined and appear to be different for Mo-on-Si and Si-on-Mo interfaces. The best results were obtained with 0.4 nm thick boron carbide layer on the Mo-on-Si interface and 0.25 nm thick boron carbide layer on the Si-on-Mo interface. Increase in reflectance is consistent with multilayers with sharper and smoother interfaces. A significant improvement in oxidation resistance of EUV multilayers has been achieved with ruthenium terminated Mo/Si multilayers. The best capping layer design consists of a Ru layer separated from the last Si layer by a boron carbide layer. This design achieves high reflectance and the best oxidation resistance in a water vapor (i.e. oxidation) environment. Electron beam exposures of 4.5 hours in the presence of 5x10{sup -7} torr water vapor partial pressure show no measurable reflectance loss and no increase in the oxide thickness of Ru terminated multilayers. Longer exposures in different environments are necessary to test lifetime stability of many years.

Bajt, S.; Almeda, J.; Naree, T.; Clift, M.; Folta, A.; Kauffman, B.; Spiller, E.

2001-10-22

435

[Traumatic recurrence of idiopathic spinal cord herniation.  

UK PubMed Central (United Kingdom)

Idiopathic spinal cord herniation is a rare cause of thoracic myelopathy and its recurrence is even more infrequent. Cord herniation is through an anterior dural defect in thoracic spine with unknown causes. Symptomatic cases must be surgically treated to reduce the hernia and seal the defect to prevent recurrences. We report a patient presenting a Brown-Séquard syndrome secondary to a D5 spinal cord herniation treated successfully and its posterior traumatic recurrence.

Lorente-Muñoz A; Cortés-Franco S; Moles-Herbera J; Casado-Pellejero J; Rivero-Celada D; Alberdi-Viñas J

2013-02-01

436

Reducing the recurrence of pilonidal sinus disease.  

UK PubMed Central (United Kingdom)

Pilonidal sinus disease is a painful disorder of the natal cleft between the buttocks. Primary treatment is by surgery but there is a high recurrence rate. Laser hair removal reduces the rate of recurrence by diminishing the number and thickness of hairs. It should be recommended along with personal hygiene measures for patients to reduce short-term and long-term recurrence of the condition.

Marza L

2013-06-01

437

Recurrent ameloblastoma of the mandible and maxilla.  

Directory of Open Access Journals (Sweden)

Full Text Available Sixteen cases of recurrent ameloblastomas of the mandible and maxilla seen over a 14 year period at the Tata Memorial Hospital were analysed with emphasis on recurrence patterns, type of primary surgery and surgical management. Seventy-five percent of the cases had conservative surgery at the first instance. In our experience, recurrent tumors could be excised widely even in unusual locations with good results.

Albuquerque K; Mehta S; Sarkar S; Mehta A

1993-01-01

438

Equine recurrent uveitis: classification, etiology, and pathogenesis.  

UK PubMed Central (United Kingdom)

Equine recurrent uveitis is a cyclical disease that affects the eye and often leads to high management costs and unfavorable results, such as blindness. Research has improved understanding of the roles of various etiologies, especially leptospirosis, in initiating and perpetuating the pathogenesis of equine recurrent uveitis. Research has also led to the discovery that specific breeds and horses with specific coat color patterns may be predisposed to developing recurrent uveitis.

Curling A

2011-06-01

439

[Recurrence frequency following traumatic shoulder dislocation  

UK PubMed Central (United Kingdom)

99 cases of primary traumatic shoulder dislocation were evaluated in regard of the influence of the time of immobilization on recurrency. 3 weeks of strict immobilization gave a recurrency rate as low as 6.4% whereas a shorter immobilization resulted in 12% of recurrency within 1--6 years. A survey from 46 other clinics as well as the literature has given no evidence of clear rules of treatment and thus the discussion of treatment remains open.

Strömsöe K; Senn E; Simmen B; Matter P

1980-06-01

440

Recurrence of anxiety disorders and its predictors.  

UK PubMed Central (United Kingdom)

BACKGROUND: The chronic course of anxiety disorders and its high burden of disease are partly due to the recurrence of anxiety disorders after remission. However, knowledge about recurrence rates and predictors of recurrence is scarce. This article reports on recurrence rates of anxiety disorders and investigates predictors of recurrence from a broad range of socio-demographic characteristics, illness-related and psychosocial putative predictors. METHODS: Baseline and 2-year follow-up data were derived from the Netherlands Study of Depression and Anxiety (NESDA). Participants who had at least one lifetime anxiety disorder (panic disorder with or without agoraphobia, agoraphobia alone, social phobia or generalized anxiety disorder), but were remitted at baseline (N=429) were included. Recurrence of anxiety disorders during the 2-year follow-up period was assessed using the Composite International Diagnostic Interview, version 2.1. RESULTS: Recurrence rates among pure and multiple anxiety disorders did not differ significantly and the overall recurrence rate of anxiety disorders was 23.5%. In those recurring, the incidence of a new anxiety disorder was common (32.7%). Disability and anxiety sensitivity remained predictive of recurrence of anxiety disorders in multivariable regression analysis. LIMITATIONS: The included participants had more severe symptoms at baseline than the non-response group and lifetime anxiety diagnoses were assessed, retrospectively. CONCLUSIONS: Recurrence of anxiety disorders is common and clinicians should be aware of the diagnostic instability within anxiety disorders. Disability and anxiety sensitivity are independent predictors of recurrence of anxiety disorders. Altering these predictors in regular cognitive behavioural therapy could contribute to the reduction of recurrence.

Scholten WD; Batelaan NM; van Balkom AJ; Wjh Penninx B; Smit JH; van Oppen P

2013-05-01

 
 
 
 
441

Understanding cardiac myxoma recurrence: a case report.  

Science.gov (United States)

Recurrence of cardiac myxoma is a rare condition, observed in about 3% of patients in sporadic cases, although it is more frequent in familial ones. Several mechanisms have been proposed to explain such recurrence, and the importance of increased vascularization as a facilitating feature is the subject of debate. The authors report the case of a non-familial right atrial myxoma, unusual for both its histopathology and recurrence. PMID:23454069

Carvalho, Maria Salomé; Andrade, Maria João; Abecasis, João; Gouveia, Rosa; Branco, Luísa; Neves, José Pedro; Mendes, Miguel

2013-02-28

442

The time profile of groin hernia recurrences.  

UK PubMed Central (United Kingdom)

PURPOSE: If the pathogeneses of the development of a recurrence varies following the different methods of hernia repair, the time required to develop a recurrence could be expected to vary. The aim of the study was to identify risk factors affecting the time interval between the primary repair and the reoperation. METHODS: Data from the Swedish Hernia Register were used. Each year of the 5-year follow-up period was treated as a separate subgroup and merged together into one large group. For each risk factor, we performed a Cox proportional hazard analysis, testing for interactions between the year and the risk factor, with reoperation as the endpoint. RESULTS: Altogether, 142,578 repairs were recorded, of which 7.7% were performed on women. The mean age of the cohort was 59 years. The overall recurrence rate in the 5-year period was 4.3%. Multivariate analysis showed that recurrence following surgery for recurrent hernia occurred relatively early (P < 0.05).Recurrence also appeared early if postoperative complications were registered (P < 0.05). Recurrence after suture repair or laparoscopic repair appeared relatively early compared to recurrence following open mesh repair (P < 0.05). In a separate analysis, a relatively higher risk for early recurrence was seen for all sutured repairs compared to all mesh repairs (P < 0.05). CONCLUSIONS: The pathogenesis behind the development of recurrence probably differs depending on the technique applied during the hernia repair. The higher proportion of early recurrences following laparoscopic repair, suture repair and recurrent repair may be explained by the high proportion of technical failures.

Magnusson N; Nordin P; Hedberg M; Gunnarsson U; Sandblom G

2010-08-01

443

Tendoscopic treatment of recurrent peroneal tendon dislocation.  

UK PubMed Central (United Kingdom)

PURPOSE: To study the possibility of tendoscopic treatment of recurrent peroneal tendon dislocation. METHODS: The case of one patient is described including the tendoscopic technique to deepen the fibular groove. RESULTS: In this single case, there were no complications, recovery time was short, and there was no recurrence of peroneal tendon dislocation. CONCLUSION: Though it seems possible to deepen the fibular groove tendoscopically, further studies are necessary to determine the role of tendoscopy in recurrent peroneal tendon dislocation.

Scholten PE; Breugem SJ; van Dijk CN

2013-06-01

444

Energy spectra for a photonic analog of multilayer graphene  

Energy Technology Data Exchange (ETDEWEB)

We present a multiple-scattering method to study the dispersion of multilayer honeycomb arrays of metallic nanoparticles. Three types of stacking are considered. It is shown that the energy spectra for these multilayer photonic structures strongly depend on the distances between the layers, stacking number of layers, and the type of stacking, which are closely analogous to the electronic ones in multilayer graphene. The effects of interlayer coupling on the energy spectra have been demonstrated by exact numerical simulations. Thus, extensive applications of such a phenomenon to design optical devices are anticipated.

Zhong Wei [Department of Physics, Beijing Normal University, Beijing 100875 (China); Zhang Xiangdong [Department of Physics, Beijing Normal University, Beijing 100875 (China); School of Physics, Beijing Institute of Technology, 100081, Beijing (China)

2011-09-15

445

Magnons in ultrahigh vacuum deposited Fe/Ag multilayers  

Energy Technology Data Exchange (ETDEWEB)

We have grown Fe/Ag multilayers with Ag buffer layer, by evaporation under UHV conditions on glass substrates. The magnetic properties of Fe/Ag multilayers are examined as a function of Fe layer thickness t {sub Fe}. The temperature dependence of the spontaneous magnetization M(T) is well described by a T {sup 3/2} law in all multilayers. A spin-wave theory has been used to explain the temperature dependence of the magnetization and the approximate values for the bulk exchange interaction J {sub b} and surface exchange interaction J {sub s} for various Fe layer thicknesses have been obtained.

El Kiadi, I. [Laboratoire de Physique des Materiaux, de Micro-electronique, Automatique et Thermique. Universite Hassan II, Faculte des Sciences Ain Chock, B.P. 5366 Maarif, Route d' El Jadida, km-8, Casablanca (Morocco)]. E-mail: i_elkiadi@yahoo.fr; Lassri, H. [Laboratoire de Physique des Materiaux, de Micro-electronique, Automatique et Thermique. Universite Hassan II, Faculte des Sciences Ain Chock, B.P. 5366 Maarif, Route d' El Jadida, km-8, Casablanca (Morocco); Benkirane, K. [Ecole Royale Navale, Bd Sour Jdid, Casablanca (Morocco); Bensassi, B. [Laboratoire de Physique des Materiaux, de Micro-electronique, Automatique et Thermique. Universite Hassan II, Faculte des Sciences Ain Chock, B.P. 5366 Maarif, Route d' El Jadida, km-8, Casablanca (Morocco)

2007-02-25

446

Magnons in ultrahigh vacuum deposited Fe/Ag multilayers  

International Nuclear Information System (INIS)

We have grown Fe/Ag multilayers with Ag buffer layer, by evaporation under UHV conditions on glass substrates. The magnetic properties of Fe/Ag multilayers are examined as a function of Fe layer thickness t Fe. The temperature dependence of the spontaneous magnetization M(T) is well described by a T 3/2 law in all multilayers. A spin-wave theory has been used to explain the temperature dependence of the magnetization and the approximate values for the bulk exchange interaction J b and surface exchange interaction J s for various Fe layer thicknesses have been obtained.

2007-02-25

447

Multilayer growth in the APS rotary deposition system.  

Energy Technology Data Exchange (ETDEWEB)

We report our progress in the growth of periodic and depth-graded multilayers in the APS rotary deposition system, a machine designed for fabrication of films tens of microns thick with thousands of layers. A computational method was employed to design depth-graded multilayers for use as wide-angular bandpass reflective optics. We present experimental results for a 154-layer WSi{sub 2}/Si multilayer system with bilayer thickness ranging from 2.2 nm to 5.5 nm that closely match theoretical flat-top reflectivity predictions of 9.8% from 15.6 mrad to 23.3 mrad at 8 keV.

Conley, R.; Liu, C.; Kewish, C.M.; Macrander, A.T.; Morawe, C.; X-Ray Science Division; European Synchrotron Radiation Facility

2007-01-01

448

Magnetoresistance of electrodeposited iron-cobalt-nickel-copper multilayers  

International Nuclear Information System (INIS)

Giant magnetoresistance (GMR) is observed in electrodeposited FeCoNiCu/Cu multilayers with Cu layer thickness varying from 1.0 to 2.5 nm at a fixed alloy layer thickness of 2.0 nm. A maximum GMR occurred at a copper layer thickness of 1.8 nm, which corresponds to the second maximum peak reported for similar multilayers fabricated by vapor deposition. The saturation magnetic field was considerably larger than that for the vapor deposited counterparts. The GMR of multilayers with a thicker alloy layer was sensitive to the magnetic field history, indicating the onset of anisotropic magnetoresistance.

2003-08-01