Using artificial neural networks to detect unknown computer worms

Detecting computer worms is a highly challenging task. We present a new approach that uses artificial neural networks (ANN) to detect the presence of computer worms based on measurements of computer behavior. We compare ANN to three other classification methods and show the advantages of ANN for detection of known worms. We then proceed to evaluate ANN’s ability to detect the presence of an unknown worm. As the measurement of a large number of system features may require significant computational resources, we evaluate three feature selection techniques. We show that, using only five features, one can detect an unknown worm with an average accuracy of 90%. We use a causal index analysis of our trained ANN to identify rules that explain the relationships between the selected features and the identity of each worm. Finally, we discuss the possible application of our approach to host-based intrusion detection systems.     

Making sense of diseases in medication reconciliation

Patients are most at risk during transitions in care across settings and providers. The communication and reconciliation of an accurate medication list throughout the care continuum are essential in the reduction in transition-related adverse drug events. Most current research focuses on the outcomes of reconciliation interventions, yet not on the clinician’s perspective. We aimed to explore clinicians’ cognitive processes and heuristics of making sense of patients’ disease histories. We used the affinity diagram method to simulate real-life medication reconciliation with 24 clinicians. The participants were given paper cards with diseases and medications representing a real case from an anesthesiology department. The task was to sort the cards in a set that made sense to the clinician. The experiment was video-recorded, and the data were analyzed using a quantitative spatial analysis technique. Levene’s test for equality of variance showed that 79% of the 24 participants arranged the diseases along a straight line (p < 0.001). With only few exceptions, the diseases were arranged along the line in a fixed order, from cardiac conditions to depression (Friedman’s χ²(44) = 291.9, p < 0.001). We learn from this study that although clinicians employ a variety of coping strategies while reconciling patients’ medical histories, there are common reconciliation strategies. Understanding heuristics and the mental models clinicians have for the reconciliation process may help to develop and implement methods and tools to promote safety research and practice.     

Incremental application of knowledge to continuously arriving time-oriented data

In our previous work, we introduced a computational architecture that effectively supports the tasks of continuous monitoring and of aggregation querying of complex domain meaningful time-oriented concepts and patterns (temporal abstractions), in environments featuring large volumes of continuously arriving and accumulating time-oriented raw data. Examples include provision of decision support in clinical medicine, making financial decisions, detecting anomalies and potential threats in communication networks, integrating intelligence information from multiple sources, etc. In this paper, we describe the general, domain-independent but task-specific problem-solving method underling our computational architecture, which we refer to as incremental knowledge-based temporal abstraction (IKBTA). The IKBTA method incrementally computes temporal abstractions by maintaining persistence and validity of continuously computed temporal abstractions from arriving time-stamped data. We focus on the computational framework underlying our reasoning method, provide well-defined semantic and knowledge requirements for incremental inference, which utilizes a logical model of time, data, and high-level abstract concepts, and provide a detailed analysis of the computational complexity of our approach.     

Specific Ortho-bromination. I. Preparation of ortho-bromo substituted benzenes

A process¹ for the synthesis of ortho-bromo aromatic compounds was studied. The process is based on the blocking and shielding effect of a tertiary butyl group which is introduced on to the aromatic ring prior to bromination. The removal of the tertiary butyl group, after bromination, is accomplished by transferring it to another aromatic nucleus via an aluminium trichloride catalysed transalkylation reaction. Synthesis of six different compounds are described and a recycle process is illustrated.     

Delayed yielding of epoxy resin under tension,compression, and flexure. I. Behavior under constant strain rate

Series of loading tests were carried out on epoxy resin specimens, at varying constant strain rates, under tension, compression, and flexure. The stress–strain relationship revealed a distinct yielding stage followed shortly by a post-yielding region of decreasing load. In all cases, results indicate linearity between yield stress and log strain rate, in accordance with Eyring's theory of viscous flow. For specimens unloaded close to the yield point, photoelastic observations revealed a residual pattern parallel to the theoretical principal shear stresses. These results, supported by additional data from other works, indicate a viscoplastic deviatoric stress-biased diffusional mechanism as the dominant factor in the yielding of an amorphous crosslinked epoxy system.     

Delayed yielding of epoxy resin. II. Behavior under constant stress

Creep tests were carried out on epoxy resin specimens at room temperature and at different high stress levels under tension, compression, and flexure. Compared with the behavior at constant strain rate (CSR) reported in Part I of this work, creep strain–time curves revealed a distinct delayed yielding region of constant minimum rate (secondary creep) followed by a post-yielding region of increasing slope (tertiary creep). In all cases, results indicate linearity between creep stress and log secondary creep rate, which is almost coincident with the corresponding relationship between yield stress and strain rate obtained in subsequent CSR loading cycles with the same specimens. The similarity in behavior under both the creep and CSR modes conforms to Eyring's theory of non-Newtonian viscous flow at high stress levels and low temperature. Theoretical analysis yields reasonable values of the activation volume, which is unaffected by the loading and test modes or by loading history, and could thus be regarded as an intrinsic parameter of the microstructure, inherently related to the viscoplastic process involved. The above considerations indicate a deviatoric stress-biased diffusional mechanism as the predominant factor in the yielding of an amorphous glassy epoxy system.     

Oriented short glass-fiber composites. IV. Dependence of mechanical properties on the distribution of fiber orientations

Short glass fiber-epoxy laminates of controlled fiber orientation and distribution were loaded to failure under uniaxial tension. The mechanical characteristics of specimens with different orientation patterns, which were determined experimentally, were compared with analytical predictions based on “Laminate Analogy” methods. Results show good agreement between empirical data and prediction in the case of stiffness, stress-strain relationship and strength based on ultimate strain criteria. A methodology is proposed according to which a well-defined, orthotropic, short fiber reinforced plastic system can be prepared, analyzed, and optimized by tailoring it according to the loading pattern in a similar manner to that of the well-established, continuous fiber reinforced laminates.     

Heuristic approach to network database external parameters design

One of the most important issues in any database design is the optimization of its performance. The external database parameters play one of the main roles in a network database performance considerations. The analytic and the simulative approaches to establish these parameters are discussed. An heuristic approach using system simulation method to find the optimal database external parameters is developed and compared with the analytic one. The software system to implement the simulation methodology is presented. This system has been successfully implemented with the VAX-11 DBMS.