Molecular Dynamics Simulation

Condensed matter systems, ranging from simple fluids and solids to complex multicomponent materials and even biological matter, are governed by well understood laws of physics, within the formal theoretical framework of quantum theory and statistical mechanics. On the relevant scales of length and time, the appropriate ‘first-principles’ description needs only the Schroedinger equation together with Gibbs averaging over the relevant statistical ensemble. However, this program cannot be carried out straightforwardly—dealing with electron correlations is still a challenge for the methods of quantum chemistry. Similarly, standard statistical mechanics makes precise explicit statements only on the properties of systems for which the many-body problem can be effectively reduced to one of independent particles or quasi-particles. [...

Combined optimization algorithms applied to pattern classification

Accurate classification by minimizing the error on test samples is the main goal in pattern classification. Combinatorial optimization is a well-known method for solving minimization problems, however, only a few examples of classifiers axe described in the literature where combinatorial optimization is used in pattern classification. Recently, there has been a growing interest in combining classifiers and improving the consensus of results for a greater accuracy. In the light of the "No Ree Lunch Theorems", we analyse the combination of simulated annealing, a powerful combinatorial optimization method that produces high quality results, with the classical perceptron algorithm. This combination is called LSA machine. Our analysis aims at finding paradigms for problem-dependent parameter settings that ensure high classifica, tion results. Our computational experiments on a large number of benchmark problems lead to results that either outperform or axe at least competitive to results published in the literature. Apart from paxameter settings, our analysis focuses on a difficult problem in computation theory, namely the network complexity problem. The depth vs size problem of neural networks is one of the hardest problems in theoretical computing, with very little progress over the past decades. In order to investigate this problem, we introduce a new recursive learning method for training hidden layers in constant depth circuits. Our findings make contributions to a) the field of Machine Learning, as the proposed method is applicable in training feedforward neural networks, and to b) the field of circuit complexity by proposing an upper bound for the number of hidden units sufficient to achieve a high classification rate. One of the major findings of our research is that the size of the network can be bounded by the input size of the problem and an approximate upper bound of 8 + √2n/n threshold gates as being sufficient for a small error rate, where n := log/SL and SL is the training set

Biosensors

A biosensor is defined as a detecting device that combines a transducer with a biologically sensitive and selective component. When a specific target molecule interacts with the biological component, a signal is produced, at transducer level, proportional to the concentration of the substance. Therefore biosensors can measure compounds present in the environment, chemical processes, food and human body at low cost if compared with traditional analytical techniques. This book covers a wide range of aspects and issues related to biosensor technology, bringing together researchers from 11 different countries. The book consists of 16 chapters written by 53 authors. The first four chapters describe several aspects of nanotechnology applied to biosensors. The subsequent section, including three chapters, is devoted to biosensor applications in the fields of drug discovery, diagnostics and bacteria detection. The principles behind optical biosensors and some of their application are discussed in chapters from 8 to 11. The last five chapters treat of microelectronics, interfacing circuits, signal transmission, biotelemetry and algorithms applied to biosensing

Object-oriented analysis and design of computational intelligence systems

Machine learning from data, neuro-fuzzy information processing, approximate reasoning and genetic and evolutionary computation are all aspects of computational intelligence (also called soft computing methods). Soft computing methods differ from conventional computing in that they are tolerant of imprecision, uncertainty and partial truths. These characteristics can be exploited to achieve tractability, robustness and low solution costs when the solution to a complex (in machine terms) problem is required. The principal constituents of soft computing include: Neural Networks, Fuzzy Logic and Probabilistic Reasoning Systems. Genetic Algorithms (GAs), Evolutionary Algorithms, Chaos Theory', Complexity Theory and parts of Learning Theory all come under Probabilistic Reasoning Systems. Hybrid systems can be designed incorporating 2 or more aspects of soft computing that are more powerful than any of the components used in a stand alone fashion. A unified framework is needed to implement and manipulate such systems. Such a framework will allow for easy visualisation of the underlying concepts and easy modification of the resulting computer models. In this thesis, an investigation of the major aspects of computational intelligence has been carried out. The main emphasis has been placed on developing an object-oriented framework for architecting computational intelligence systems. Object models for Neural Networks, Fuzzy Logic Systems and Evolutionary Computation systems have been developed. Software has been written in C++ to realise sample implementations of the various systems. Finally, practical applications and the results of using the Neural Networks, Fuzzy Logic systems and Genetic Algorithms developed in solving real world problems are presented. A consistent notation based on the Object Modelling Technique (OMT) is used throughout the thesis to describe the software architectures from which the computer implementation models have been derived

Life Sciences Program Tasks and Bibliography for FY 1996

This document includes information on all peer reviewed projects funded by the Office of Life and Microgravity Sciences and Applications, Life Sciences Division during fiscal year 1996. This document will be published annually and made available to scientists in the space life sciences field both as a hard copy and as an interactive Internet web page