108 research outputs found

    Dynamic neural network architecture inspired by the immune algorithm to predict preterm deliveries in pregnant women

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    There has been some improvement in the treatment of preterm infants, which has helped to increase their chance of survival. However, the rate of premature births is still globally increasing. As a result, this group of infants is most at risk of developing severe medical conditions that can affect the respiratory, gastrointestinal, immune, central nervous, auditory and visual systems. There is a strong body of evidence emerging that suggests the analysis of uterine electrical signals, from the abdominal surface (Electrohysterography – EHG), could provide a viable way of diagnosing true labour and even predict preterm deliveries. This paper explores this idea further and presents a new dynamic self-organized network immune algorithm that classifies term and preterm records, using an open dataset containing 300 records (38 preterm and 262 term). Using the dataset, oversampling and cross validation techniques are evaluated against other similar studies. The proposed approach shows an improvement on existing studies with 89% sensitivity, 91% specificity, 90% positive predicted value, 90% negative predicted value, and an overall accuracy of 90%

    A Dynamic Neural Network Architecture with immunology Inspired Optimization for Weather Data Forecasting

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    Recurrent neural networks are dynamical systems that provide for memory capabilities to recall past behaviour, which is necessary in the prediction of time series. In this paper, a novel neural network architecture inspired by the immune algorithm is presented and used in the forecasting of naturally occurring signals, including weather big data signals. Big Data Analysis is a major research frontier, which attracts extensive attention from academia, industry and government, particularly in the context of handling issues related to complex dynamics due to changing weather conditions. Recently, extensive deployment of IoT, sensors, and ambient intelligence systems led to an exponential growth of data in the climate domain. In this study, we concentrate on the analysis of big weather data by using the Dynamic Self Organized Neural Network Inspired by the Immune Algorithm. The learning strategy of the network focuses on the local properties of the signal using a self-organised hidden layer inspired by the immune algorithm, while the recurrent links of the network aim at recalling previously observed signal patterns. The proposed network exhibits improved performance when compared to the feedforward multilayer neural network and state-of-the-art recurrent networks, e.g., the Elman and the Jordan networks. Three non-linear and non-stationary weather signals are used in our experiments. Firstly, the signals are transformed into stationary, followed by 5-steps ahead prediction. Improvements in the prediction results are observed with respect to the mean value of the error (RMS) and the signal to noise ratio (SNR), however to the expense of additional computational complexity, due to presence of recurrent links

    The application of dynamic self-organised multilayer network inspired by the Immune Algorithm for weather signals forecast

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    Neural network architecture called Dynamic Self-organised Multilayer Network Inspired by the Immune Algorithm is proposed for the prediction of weather signals. Two sets of experiments have been implemented. The simulation results showed slight improvement achieved by the proposed network when using the average results of 30 simulations. For the second set of experiments, the simulation results indicated that there is no significant improvement over the first set of experiments. Since clustering methods have been widely used in different applications of data mining, the adaption of unsupervised learning in the proposed network might serve these different applications, for example, medical diagnostics and pattern recognition for big data. The structure of the proposed network can be modified for clustering tasks by changing the back-propagation algorithm in the output layer. This can extend the application of the proposed network to scientifically analyse different types of big data

    DYNAMIC SELF-ORGANISED NEURAL NETWORK INSPIRED BY THE IMMUNE ALGORITHM FOR FINANCIAL TIME SERIES PREDICTION AND MEDICAL DATA CLASSIFICATION

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    Artificial neural networks have been proposed as useful tools in time series analysis in a variety of applications. They are capable of providing good solutions for a variety of problems, including classification and prediction. However, for time series analysis, it must be taken into account that the variables of data are related to the time dimension and are highly correlated. The main aim of this research work is to investigate and develop efficient dynamic neural networks in order to deal with data analysis issues. This research work proposes a novel dynamic self-organised multilayer neural network based on the immune algorithm for financial time series prediction and biomedical signal classification, combining the properties of both recurrent and self-organised neural networks. The first case study that has been addressed in this thesis is prediction of financial time series. The financial time series signal is in the form of historical prices of different companies. The future prediction of price in financial time series enables businesses to make profits by predicting or simply guessing these prices based on some historical data. However, the financial time series signal exhibits a highly random behaviour, which is non-stationary and nonlinear in nature. Therefore, the prediction of this type of time series is very challenging. In this thesis, a number of experiments have been simulated to evaluate the ability of the designed recurrent neural network to forecast the future value of financial time series. The resulting forecast made by the proposed network shows substantial profits on financial historical signals when compared to the self-organised hidden layer inspired by immune algorithm and multilayer perceptron neural networks. These results suggest that the proposed dynamic neural networks has a better ability to capture the chaotic movement in financial signals. The second case that has been addressed in this thesis is for predicting preterm birth and diagnosing preterm labour. One of the most challenging tasks currently facing the healthcare community is the identification of preterm labour, which has important significances for both healthcare and the economy. Premature birth occurs when the baby is born before completion of the 37-week gestation period. Incomplete understanding of the physiology of the uterus and parturition means that premature labour prediction is a difficult task. The early prediction of preterm births could help to improve prevention, through appropriate medical and lifestyle interventions. One promising method is the use of Electrohysterography. This method records the uterine electrical activity during pregnancy. In this thesis, the proposed dynamic neural network has been used for classifying between term and preterm labour using uterine signals. The results indicated that the proposed network generated improved classification accuracy in comparison to the benchmarked neural network architectures

    The Performance of Immune Based Neural Network with Financial Time Series Prediction

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    This paper presents the use of immune based neural networks which include multilayer perceptron and functional neural network for the prediction of financial time series signals. Extensive simulations for the prediction of one and five steps ahead of stationary and non-stationary time series were performed which indicate that immune based neural networks in most cases demonstrated advantages in capturing chaotic movement in the financial signals with an improvement in the profit return and rapid convergence over multilayer perceptrons

    Efficient Learning Machines

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    Computer scienc

    Self-learning modules for spectra evaluation

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    Monitoring milk processing is an essential task as it affects the quality and safety of the final product. The aim of this investigation was to develop and analyse the self-learning system for the supervision of the processing of milk. In the self-learning evaluation module, several algorithms for data analysis of near infrared (NIR) and Raman spectra was implemented for the prediction of sample quality and safety. In the first part of this thesis, the use of NIR spectroscopy for controlling milk processing was investigated. For this reason, a high-quality quartz flow cell with a 1 mm pathlength including temperature controlling option for liquids was implemented. For sample preparation, UHT-milk with 1.5 % fat content was measured at 5 °C and considered as the reference milk. Samples with various changes such as added water and cleaning solution, different fat content and temperature as well as milks from various suppliers were investigated as the modified samples. A data set from reference and modified samples was obtained with NIR measurements. In this study, first Savitzky-Golay derivative with second polynomial order and window size of 15 was applied. It was compared with the usefulness of raw spectrum and also the combination of raw and first derivative spectrum. For the self-learning sector, an autoencoder neural network was employed. Within this thesis, it was shown that the trained autoencoder using first derivative spectra was capable to detect 5 % added water and 9 % cleaning solution in the milk. However, by using the combination spectra, the difference of 0.1 % in fat concentration was perfectly recognized. These two procedures were able to detect milks from different suppliers and difference of 10 °C in the measurement temperature. Another part of this work was done using Raman spectroscopy. The aim of this part was to check if the previous result can be improved. In this step, the circulation method was again employed the same as in the previous part. However, because of the heat introduced to the sample by the laser using in Raman spectroscopy and the length of plastic tubes which can be affected by the temperature of the laboratory, the measurement temperature was kept at 10 °C. 1.5 % fat UHT milk was utilized as the reference sample. Milks with various changes such as different fat contents, various measurement temperatures and added water or cleaning solution were investigated as the modified samples. In this investigation, not only the autoencoder but also some chemometric models were utilized with the purpose of anomaly detection. Principal component analysis (PCA) was investigated to check if the various samples can becategorized separately. In addition, two chemometric modelling techniques such as principal component regression and Gaussian process regression were tested to check the ability for change detection. By using the results obtained by PCA, a sufficient categorization of various samples was not achieved. While the PCR did not present a promising prediction as the related R2 was 0.7, Gaussian process regression with R2 of 0.97 predicted the changes almost perfectly. The trained autoencoder and Gaussian process regression both were able to define 5 % water and cleaning solution, difference of 0.1 % fat content, and variation of 5 °C in the measurement temperature. In comparison between the autoencoder and Gaussian process regression, it should be mentioned that the Gaussian process regression was capable to determine more abnormal signals than the autoencoder, however, it must be trained with all the possible changes. In contrast, the autoencoder can be trained once just with reference signals and used in online monitoring properly. As the final part and to detect which type of anomalies happened during the milk processing, several classification approaches such as linear discriminant analysis, decision tree, support vector machine, and k nearest neighbour were utilized. While decision trees and linear discriminant analysis failed to effectively characterize the various types of anomalies, the k nearest neighbor and support vector machine presented promising results. The support vector machine presented an accuracy of 81.4 % for test set, while the k nearest neighbor showed an accuracy of 84.8 %. As a result, it is reasonable to assume that both algorithms are capable of classifying various groups of data accurately. It can help the milk business figure out whats going wrong during the processing of milk. In general, Raman spectroscopy produced better findings than NIR spectroscopy, because the typical absorption bands of milk components in NIR spectrometers may be impacted by high water absorption combined with substantial light scattering by fat globules. Additionally, the autoencoder as self-learning system was capable of correctly detecting changes during milk processing, however, classification algorithms can aid in obtaining more details.Die Überwachung der Milchverarbeitung ist eine wesentliche Aufgabe, da sie die QualitĂ€t und Sicherheit des Endprodukts beeinflusst. Das Ziel dieser Untersuchung war die Entwicklung und Analyse eines selbstlernenden Systems zur Überwachung der Milchverarbeitung. In dem selbstlernenden Auswertungsmodul wurden verschiedene Algorithmen zur Datenanalyse implementiert, um die QualitĂ€t und Sicherheit der Proben mit Hilfe spektroskopischer Methoden vorherzusagen. Im ersten Teil dieser Arbeit wurde der Einsatz der Nahinfrarot-Spektroskopie (NIR) zur Kontrolle der Milchverarbeitung untersucht. Zu diesem Zweck wurde eine hochwertige Quarzdurchflusszelle mit einer Schichtdicke von 1 mm und einer Temperiermöglichkeit fĂŒr FlĂŒssigkeiten eingesetzt. Zur Probenvorbereitung wurde UHT-Milch mit 1,5 % Fettgehalt bei 5 °C gemessen und als Referenzmilch betrachtet. Als modifizierte Proben wurden Proben mit verschiedenen VerĂ€nderungen wie Wasser- und Reinigungsmittelzusatz, unterschiedlichem Fettgehalt und Temperatur sowie Milch von verschiedenen Lieferanten untersucht. Mit NIR Messungen wurde ein Datensatz von Referenz- und modifizierten Proben gewonnen. In dieser Studie wurde die erste Savitzky-Golay-Ableitung mit zweiter Polynomordnung und einer FenstergrĂ¶ĂŸe von 15 verwendet. Sie wurde mit der AuswertegĂŒte des Rohspektrums und auch der Kombination aus Roh- und erstem Ableitungsspektrum verglichen. FĂŒr den selbstlernenden Bereich wurde ein neuronales Netz als Autoencoder eingesetzt. Im Rahmen dieser Arbeit wurde gezeigt, dass der trainierte Autoencoder unter Verwendung der ersten Ableitung in der Lage war, 5 % zugesetztes Wasser und 9 % Reinigungslösung in der Milch zu erkennen. Durch die Verwendung der Kombinationsspektren wurde auch der Unterschied von 0,1 % in der Fettkonzentration perfekt erkannt. Diese beiden Verfahren waren in der Lage, Milch von verschiedenen Lieferanten und einem Unterschied von 10 °C bei der Messtemperatur zu erkennen. Ein weiterer Teil dieser Arbeit wurde mit der Raman-Spektroskopie durchgefĂŒhrt. Ziel dieses Teils war es, zu prĂŒfen, ob das vorherige Ergebnis verbessert werden kann. In diesem Schritt wurde wieder die gleiche Zirkulationsmethode wie im vorherigen Teil verwendet. Wegen der WĂ€rme, die durch den Laser bei der Raman-Spektroskopie in die Probe eingebracht wird, und der LĂ€nge der Kunststoffrohre, die durch die Temperatur im Labor beeinflusst werden kann, wurde die Messtemperatur jedoch bei 10 °C gehalten. Als Referenzprobe wurde UHT-Milch mit 1,5 % Fett verwendet. Milch mit verschiedenen VerĂ€nderungen wie unterschiedlichen Fettgehalten, verschiedenen Messtemperaturen und Zusatz von Wasser oder Reinigungslösung wurde als modifizierte Probe untersucht. In dieser Untersuchung wurden nicht nur der Autoencoder, sondern auch einige chemometrische Modelle zur Erkennung von Anomalien eingesetzt. Die Hauptkomponentenanalyse (PCA) wurde untersucht, um zu prĂŒfen, ob die verschiedenen Proben separat kategorisiert werden können. DarĂŒber hinaus wurden zwei chemometrische Modellierungstechniken wie die Hauptkomponentenregression und die Gaußsche Prozessregression getestet, um die FĂ€higkeit zur Erkennung von VerĂ€nderungen zu prĂŒfen. Mit den Ergebnissen der PCA konnte keine ausreichende Kategorisierung der verschiedenen Proben erreicht werden. WĂ€hrend die Hauptkomponentenregression (PCR) keine vielversprechende Vorhersage lieferte, da das zugehörige R2 bei 0,7 lag, sagte die Gaußsche Prozessregression mit einem R2 von 0,97 die VerĂ€nderungen nahezu perfekt voraus. Sowohl der trainierte Autoencoder als auch die Gaußsche Prozessregression waren in der Lage, 5 % Wasser und Reinigungslösung, einen Unterschied von 0,1 % Fettgehalt und eine Variation der Messtemperatur von 5 °C zu detektieren. Im Vergleich von Autoencoder und der Gaußschen Prozessregression ist zu erwĂ€hnen, dass die Gaußsche Prozessregression in der Lage war, mehr anormale Signale zu bestimmen als der Autoencoder, allerdings muss sie mit allen möglichen Änderungentrainiert werden. Im Gegensatz dazu muss der Autoencoder nur einmal mit Referenzsignalentrainiert und kann dann fĂŒr die Online-Überwachung verwendet werden. Als letzter Teil und umzu erkennen, welche Art von Anomalien wĂ€hrend der Milchverarbeitung auftraten, wurden verschiedene KlassifizierungsansĂ€tze wie lineare Diskriminanzanalyse, Entscheidungsbaum, Support Vector Machine und K Nearest Neighbour verwendet. WĂ€hrend die EntscheidungsbĂ€ume und die lineare Diskriminanzanalyse nicht in der Lage waren, die verschiedenen Arten von Anomalien effektiv zu charakterisieren, lieferten die K Nearest Neighbour und die Support Vector Machine Methode vielversprechende Ergebnisse. Die Support Vector Machine wies eine Genauigkeit von 81,4 % fĂŒr den Testsatz auf, wĂ€hrend die K Nearest Neighbour Methode eine Genauigkeit von 84,8 % ergab. Daher kann man davon ausgehen, dass beide Algorithmen in der Lage sind, verschiedene Datengruppen genau zu klassifizieren. Dies kann der Milchwirtschaft helfen, herauszufinden, was bei der Verarbeitung von Milch falsch lĂ€uft. Im Allgemeinen lieferte die Raman-Spektroskopie bessere Ergebnisse als die NIR-Spektroskopie, da die typischen Absorptionsbanden der Milchbestandteile in NIR-Spektrometern durch eine hohe Wasserabsorption in Kombination mit einer erheblichen Lichtstreuung durch FettkĂŒgelchen beeintrĂ€chtigt werden können. DarĂŒber hinaus war der Autoencoder als selbstlernendes System in der Lage, VerĂ€nderungen wĂ€hrend der Milchverarbeitung korrekt zu erkennen, jedoch können Klassifizierungsalgorithmen helfen, mehr Details zu erhalten

    Über die Selbstorganisation einer hierarchischen GedĂ€chtnisstruktur fĂŒr kompositionelle ObjektreprĂ€sentation im visuellen Kortex

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    At present, there is a huge lag between the artificial and the biological information processing systems in terms of their capability to learn. This lag could be certainly reduced by gaining more insight into the higher functions of the brain like learning and memory. For instance, primate visual cortex is thought to provide the long-term memory for the visual objects acquired by experience. The visual cortex handles effortlessly arbitrary complex objects by decomposing them rapidly into constituent components of much lower complexity along hierarchically organized visual pathways. How this processing architecture self-organizes into a memory domain that employs such compositional object representation by learning from experience remains to a large extent a riddle. The study presented here approaches this question by proposing a functional model of a self-organizing hierarchical memory network. The model is based on hypothetical neuronal mechanisms involved in cortical processing and adaptation. The network architecture comprises two consecutive layers of distributed, recurrently interconnected modules. Each module is identified with a localized cortical cluster of fine-scale excitatory subnetworks. A single module performs competitive unsupervised learning on the incoming afferent signals to form a suitable representation of the locally accessible input space. The network employs an operating scheme where ongoing processing is made of discrete successive fragments termed decision cycles, presumably identifiable with the fast gamma rhythms observed in the cortex. The cycles are synchronized across the distributed modules that produce highly sparse activity within each cycle by instantiating a local winner-take-all-like operation. Equipped with adaptive mechanisms of bidirectional synaptic plasticity and homeostatic activity regulation, the network is exposed to natural face images of different persons. The images are presented incrementally one per cycle to the lower network layer as a set of Gabor filter responses extracted from local facial landmarks. The images are presented without any person identity labels. In the course of unsupervised learning, the network creates simultaneously vocabularies of reusable local face appearance elements, captures relations between the elements by linking associatively those parts that encode the same face identity, develops the higher-order identity symbols for the memorized compositions and projects this information back onto the vocabularies in generative manner. This learning corresponds to the simultaneous formation of bottom-up, lateral and top-down synaptic connectivity within and between the network layers. In the mature connectivity state, the network holds thus full compositional description of the experienced faces in form of sparse memory traces that reside in the feed-forward and recurrent connectivity. Due to the generative nature of the established representation, the network is able to recreate the full compositional description of a memorized face in terms of all its constituent parts given only its higher-order identity symbol or a subset of its parts. In the test phase, the network successfully proves its ability to recognize identity and gender of the persons from alternative face views not shown before. An intriguing feature of the emerging memory network is its ability to self-generate activity spontaneously in absence of the external stimuli. In this sleep-like off-line mode, the network shows a self-sustaining replay of the memory content formed during the previous learning. Remarkably, the recognition performance is tremendously boosted after this off-line memory reprocessing. The performance boost is articulated stronger on those face views that deviate more from the original view shown during the learning. This indicates that the off-line memory reprocessing during the sleep-like state specifically improves the generalization capability of the memory network. The positive effect turns out to be surprisingly independent of synapse-specific plasticity, relying completely on the synapse-unspecific, homeostatic activity regulation across the memory network. The developed network demonstrates thus functionality not shown by any previous neuronal modeling approach. It forms and maintains a memory domain for compositional, generative object representation in unsupervised manner through experience with natural visual images, using both on- ("wake") and off-line ("sleep") learning regimes. This functionality offers a promising departure point for further studies, aiming for deeper insight into the learning mechanisms employed by the brain and their consequent implementation in the artificial adaptive systems for solving complex tasks not tractable so far.GegenwĂ€rtig besteht immer noch ein enormer Abstand zwischen der LernfĂ€higkeit von kĂŒnstlichen und biologischen Informationsverarbeitungssystemen. Dieser Abstand ließe sich durch eine bessere Einsicht in die höheren Funktionen des Gehirns wie Lernen und GedĂ€chtnis verringern. Im visuellen Kortex etwa werden die Objekte innerhalb kĂŒrzester Zeit entlang der hierarchischen Verarbeitungspfade in ihre Bestandteile zerlegt und so durch eine Komposition von Elementen niedrigerer KomplexitĂ€t dargestellt. Bereits bekannte Objekte werden so aus dem LangzeitgedĂ€chtnis abgerufen und wiedererkannt. Wie eine derartige kompositionell-hierarchische GedĂ€chtnisstruktur durch die visuelle Erfahrung zustande kommen kann, ist noch weitgehend ungeklĂ€rt. Um dieser Frage nachzugehen, wird hier ein funktionelles Modell eines lernfĂ€higen rekurrenten neuronalen Netzwerkes vorgestellt. Im Netzwerk werden neuronale Mechanismen implementiert, die der kortikalen Verarbeitung und PlastizitĂ€t zugrunde liegen. Die hierarchische Architektur des Netzwerkes besteht aus zwei nacheinander geschalteten Schichten, die jede eine Anzahl von verteilten, rekurrent vernetzten Modulen beherbergen. Ein Modul umfasst dabei mehrere funktionell separate Subnetzwerke. Jedes solches Modul ist imstande, aus den eintreffenden Signalen eine geeignete ReprĂ€sentation fĂŒr den lokalen Eingaberaum unĂŒberwacht zu lernen. Die fortlaufende Verarbeitung im Netzwerk setzt sich zusammen aus diskreten Fragmenten, genannt Entscheidungszyklen, die man mit den schnellen kortikalen Rhythmen im gamma-Frequenzbereich in Verbindung setzen kann. Die Zyklen sind synchronisiert zwischen den verteilten Modulen. Innerhalb eines Zyklus wird eine lokal umgrenzte winner-take-all-Ă€hnliche Operation in Modulen durchgefĂŒhrt. Die KompetitionsstĂ€rke wĂ€chst im Laufe des Zyklus an. Diese Operation aktiviert in AbhĂ€ngigkeit von den Eingabesignalen eine sehr kleine Anzahl von Einheiten und verstĂ€rkt sie auf Kosten der anderen, um den dargebotenen Reiz in der NetzwerkaktivitĂ€t abzubilden. Ausgestattet mit adaptiven Mechanismen der bidirektionalen synaptischen PlastizitĂ€t und der homöostatischen AktivitĂ€tsregulierung, erhĂ€lt das Netzwerk natĂŒrliche Gesichtsbilder von verschiedenen Personen dargeboten. Die Bilder werden der unteren Netzwerkschicht, je ein Bild pro Zyklus, als Ansammlung von Gaborfilterantworten aus lokalen Gesichtslandmarken zugefĂŒhrt, ohne Information ĂŒber die PersonenidentitĂ€t zur VerfĂŒgung zu stellen. Im Laufe der unĂŒberwachten Lernprozedur formt das Netzwerk die Verbindungsstruktur derart, dass die Gesichter aller dargebotenen Personen im Netzwerk in Form von dĂŒnn besiedelten GedĂ€chtnisspuren abgelegt werden. Hierzu werden gleichzeitig vorwĂ€rtsgerichtete (bottom-up) und rekurrente (lateral, top-down) synaptische Verbindungen innerhalb und zwischen den Schichten gelernt. Im reifen Verbindungszustand werden infolge dieses Lernens die einzelnen Gesichter als Komposition ihrer Bestandteile auf generative Art gespeichert. Dank der generativen Art der gelernten Struktur reichen schon allein das höhere IdentitĂ€tssymbol oder eine kleine Teilmenge von zugehörigen Gesichtselementen, um alle Bestandteile der gespeicherten Gesichter aus dem GedĂ€chtnis abzurufen. In der Testphase kann das Netzwerk erfolgreich sowohl die IdentitĂ€t als auch das Geschlecht von Personen aus vorher nicht gezeigten Gesichtsansichten erkennen. Eine bemerkenswerte Eigenschaft der entstandenen GedĂ€chtnisarchitektur ist ihre FĂ€higkeit, ohne Darbietung von externen Stimuli spontan AktivitĂ€tsmuster zu generieren und die im GedĂ€chtnis abgelegten Inhalte in diesem schlafĂ€hnlichen "off-line" Regime wiederzugeben. Interessanterweise ergibt sich aus der Schlafphase ein direkter Vorteil fĂŒr die GedĂ€chtnisfunktion. Dieser Vorteil macht sich durch eine drastisch verbesserte Erkennungsrate nach der Schlafphase bemerkbar, wenn das Netwerk mit den zuvor nicht dargebotenen Ansichten von den bereits bekannten Personen konfrontiert wird. Die Leistungsverbesserung nach der Schlafphase ist umso deutlicher, je stĂ€rker die Alternativansichten vom Original abweichen. Dieser positive Effekt ist zudem komplett unabhĂ€ngig von der synapsenspezifischen PlastizitĂ€t und kann allein durch die synapsenunspezifische, homöostatische Regulation der AktivitĂ€t im Netzwerk erklĂ€rt werden. Das entwickelte Netzwerk demonstriert so eine im Bereich der neuronalen Modellierung bisher nicht gezeigte FunktionalitĂ€t. Es kann unĂŒberwacht eine GedĂ€chtnisdomĂ€ne fĂŒr kompositionelle, generative ObjektreprĂ€sentation durch die Erfahrung mit natĂŒrlichen Bildern sowohl im reizgetriebenen, wachĂ€hnlichen Zustand als auch im reizabgekoppelten, schlafĂ€hnlichen Zustand formen und verwalten. Diese FunktionalitĂ€t bietet einen vielversprechenden Ausgangspunkt fĂŒr weitere Studien, die die neuronalen Lernmechanismen des Gehirns ins Visier nehmen und letztendlich deren konsequente Umsetzung in technischen, adaptiven Systemen anstreben

    Classification Techniques Using EHG Signals for Detecting Preterm Births

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    Premature birth is defined as an infant born before 37 weeks of gestation and can be sub-categorized into three phrases; late preterm delivery between 34 and 36 weeks of gestation; moderately preterm between 32 and 34 weeks, and extreme preterm less than 28 weeks of gestation. Globally, the rate of preterm births is increasing, thus resulting in significant health, development and economic problems. The current methods for the detection of preterm birth are inadequate due to the fact that the exact cause of premature uterine contractions leading to delivery is mostly unknown. Another problem is the interpretation of temporal and spectral characteristics of Electromyography (EMG), which is an electrodiagnostic medicine technique for recording and evaluating the electrical activity produced by uterine muscles during pregnancy and parturition – significant variability exists among obstetric care practitioners. Apart from a small number of potential causes for preterm birth, such as medication, uterine over-distension, preterm premature rupture of membranes (PPROM), intrauterine inflammation, precocious foetal endocrine activation, surgery, ethnicity and lifestyle, there is still a large amount of uncertainty about their specific risks. Hence, it is currently very difficult to make reliable predictions about preterm delivery risk. There has also been some evidence that the analysis of uterine electrical signals, collected from the abdominal surface, could provide an independent and easier way to diagnose true labour and detect the onset of preterm delivery. Early detection opens up new avenues for the development of an automated ambulatory system, based on uterine EMG, for patient monitoring during pregnancy. This can be made possible through the use of machine learning. The essence of machine learning is the utilisation of previously recorded data outcomes to train algorithms to ii stimulate software learning elements. Such learned models can, as a result, be used to detect and predict the early signs associated with the onset of preterm birth. Therefore in this thesis, Electrohysterography signals are used to classify uterine activity associated with preterm birth. This is achieved using an open dataset, which contains 262 records for women who delivered at term and 38 who delivered prematurely. Several new features from Electromyography studies are utilized, as well as feature-ranking techniques to determine their discriminative capabilities in detecting term and preterm records. The results illustrate that the combination of the Levenberg-Marquardt trained Feed-Forward Neural Network, Radial Basis Function Neural Network and the Random Neural Network classifiers performed the best, with 91% for sensitivity, 84% for specificity, 94% for the area under the curve and 12% for the mean error rate. Applying advanced machine learning algorithms, in conjunction with innovative signal processing techniques and the analysis of Electrohysterography signals shows significant benefits for use in clinical interventions for preterm birth assessments
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