Showing papers by "SRI International published in 2002"

Physics of Shock Waves and High-Temperature Hydrodynamic Phenomena

Abstract: : Contents: Elements of gas dynamics and classical theory of shock waves; thermal radiation and radiant heat exchange in a medium; thermodynamic properties of gases at high temperatures; shock tubes; absorption and emission of radiation in gases at high temperatures; speed of relaxation processes in gases; structure of front of shock waves in gases; physico-chemical kinetics in hydrodynamic processes; light phenomena in shock waves and during strong explosion in air; thermal waves; shock waves in solids; certain self-similar processes in gas dynamics.

DAML-S: Web Service Description for the Semantic Web

Abstract: In this paper we present DAML-S, a DAML+OIL ontology for describing the properties and capabilities of Web Services. Web Services - Web-accessible programs and devices - are garnering a great deal of interest from industry, and standards are emerging for low-level descriptions of Web Services. DAML-S complements this effort by providing Web Service descriptions at the application layer, describing what a service can do, and not just how it does it. In this paper we describe three aspects of our ontology: the service profile, the process model, and the service grounding. The paper focuses on the grounding, which connects our ontology with low-level XML-based descriptions of Web Services.

Simulation, verification and automated composition of web services

Abstract: Web services -- Web-accessible programs and devices - are a key application area for the Semantic Web. With the proliferation of Web services and the evolution towards the Semantic Web comes the opportunity to automate various Web services tasks. Our objective is to enable markup and automated reasoning technology to describe, simulate, compose, test, and verify compositions of Web services. We take as our starting point the DAML-S DAML+OIL ontology for describing the capabilities of Web services. We define the semantics for a relevant subset of DAML-S in terms of a first-order logical language. With the semantics in hand, we encode our service descriptions in a Petri Net formalism and provide decision procedures for Web service simulation, verification and composition. We also provide an analysis of the complexity of these tasks under different restrictions to the DAML-S composite services we can describe. Finally, we present an implementation of our analysis techniques. This implementation takes as input a DAML-S description of a Web service, automatically generates a Petri Net and performs the desired analysis. Such a tool has broad applicability both as a back end to existing manual Web service composition tools, and as a stand-alone tool for Web service developers.

EMERALD: Event Monitoring Enabling Responses to Anomalous Live Disturbances

Abstract: The EMERALD (Event Monitoring Enabling Responses to Anomalous Live Disturbances) environment is a distributed scalable tool suite for tracking malicious activity through and across large networks. EMERALD introduces a highly distributed, building-block approach to network surveillance, attack isolation, and automated response. It combines models from research in distributed high-volume event-correlation methodologies with over a decade of intrusion detection research and engineering experience. The approach is novel in its use of highly distributed, independently tunable, surveillance and response monitors that are deployable polymorphically at various abstract layers in a large network. These monitors contribute to a streamlined event-analysis system that combines signature analysis with statistical profiling to provide localized real-time protection of the most widely used network services on the Internet. Equally important, EMERALD introduces a recursive framework for coordinating the dissemination of analyses from the distributed monitors to provide a global detection and response capability that can counter attacks occurring across an entire network enterprise. Further, EMERALD introduces a versatile application programmers' interface that enhances its ability to integrate with heterogeneous target hosts and provides a high degree of interoperability with third-party tool suites.

The Pathway Tools software.

Abstract: Motivation: Bioinformatics requires reusable software tools for creating model-organism databases (MODs). Results: The Pathway Tools is a reusable, productionquality software environment for creating a type of MOD called a Pathway/Genome Database (PGDB). A PGDB such as EcoCyc (see http://ecocyc.org) integrates our evolving understanding of the genes, proteins, metabolic network, and genetic network of an organism. This paper provides an overview of the four main components of the Pathway Tools: The PathoLogic component supports creation of new PGDBs from the annotated genome of an organism. The Pathway/Genome Navigator provides query, visualization, and Web-publishing services for PGDBs. The Pathway/Genome Editors support interactive updating of PGDBs. The Pathway Tools ontology defines the schema of PGDBs. The Pathway Tools makes use of the Ocelot object database system for data management services for PGDBs. The Pathway Tools has been used to build PGDBs for 13 organisms within SRI and by external

The EcoCyc Database

Abstract: EcoCyc is an organism-specific pathway/genome database that describes the metabolic and signal-transduction pathways of Escherichia coli, its enzymes, its transport proteins and its mechanisms of transcriptional control of gene expression. EcoCyc is queried using the Pathway Tools graphical user interface, which provides a wide variety of query operations and visualization tools. EcoCyc is available at http://ecocyc.org/.

An algebraic approach to IP traceback

Abstract: We present a new solution to the problem of determining the path a packet traversed over the Internet (called the traceback problem) during a denial-of-service attack. This article reframes the traceback problem as a polynomial reconstruction problem and uses algebraic techniques from coding theory and learning theory to provide robust methods of transmission and reconstruction.

The MetaCyc Database

Abstract: MetaCyc is a metabolic-pathway database that describes 445 pathways and 1115 enzymes occurring in 158 organisms. MetaCyc is a review-level database in that a given entry in MetaCyc often integrates information from multiple literature sources. The pathways in MetaCyc were determined experimentally, and are labeled with the species in which they are known to occur based on literature references examined to date. MetaCyc contains extensive commentary and literature citations. Applications of MetaCyc include pathway analysis of genomes, metabolic engineering and biochemistry education. MetaCyc is queried using the Pathway Tools graphical user interface, which provides a wide variety of query operations and visualization tools. MetaCyc is available via the World Wide Web at http://ecocyc.org/ecocyc/metacyc.html, and is available for local installation as a binary program for the PC and the Sun workstation, and as a set of flatfiles. Contact metacyc-info@ai.sri.com for information on obtaining a local copy of MetaCyc.

Method and apparatus for disseminating topology information and for discovering new neighboring nodes

Abstract: A proactive link-state routing protocol designed for mobile ad-hoc networks is disclosed, which provides hop-by-hop routing along shortest paths to each destination. Each node running the present protocol will compute a source tree (providing paths to all reachable nodes) based on partial topology information stored in its topology table. To minimize overhead, each node reports only “part” of its source tree to neighbors. The present invention employs a combination of periodic and differential updates to keep all neighbors informed of the reportable part of its source tree. The present invention performs neighbor discovery using “differential” HELLO messages that report only “changes” in the status of neighbors. This results in HELLO messages that are much smaller than those of other link-state routing protocols.

A walk on the WILD side How wireless handhelds may change computer-supported collaborative learning

Abstract: Designs for CSCL (Computer-Supported Collaborative Learning) applications usually presume a desktop or laptop computer. Yet future classrooms are likely to be organized around Wireless Internet Learning Devices (WILD) that resemble graphing calculators, Palm, or Pocket-PC handhelds, connected by short-range wireless networking. WILD learning will have physical affordances that are different from today’s computer lab, and different from classrooms with 5 students per computer. These differing affordances may lead to learning activities that deviate significantly from today’s images of K-12 CSCL activities. Drawing upon research across a range of recent handheld projects, we suggest application-level affordances around which WILD-based CSCL has begun to organize: (a) augmenting physical space, (b) leveraging topological space, (c) aggregating coherently across all students, (d) conducting the class, and (e) act becomes artifact. We speculate on how CSCL research may consequently evolve towards a focus on kinds of systemic coupling in an augmented activity space.

Dielectric elastomer artificial muscle actuators: toward biomimetic motion

Abstract: To achieve desirable biomimetic motion, actuators must be able to reproduce the important features of natural muscle such as power, stress, strain, speed of response, efficiency, and controllability. It is a mistake, however, to consider muscle as only an energy output device. Muscle is multifunctional. In locomotion, muscle often acts as an energy absorber, variable-stiffness suspension element, or position sensor, for example. Electroactive polymer technologies based on the electric-field-induced deformation of polymer dielectrics with compliant electrodes are particularly promising because they have demonstrated high strains and energy densities. Testing with experimental biological techniques and apparatus has confirmed that these dielectric elastomer artificial muscles can indeed reproduce several of the important characteristics of natural muscle. Several different artificial muscle actuator configurations have been tested, including flat actuators and tubular rolls. Rolls have been shown to act as structural elements and to incorporate position sensing. Biomimetic robot applications have been explored that exploit the muscle-like capabilities of the dielectric elastomer actuators, including serpentine manipulators, insect-like flapping-wing mechanisms, and insect-like walking robots.

Electroelastomers: Applications of dielectric elastomer transducers for actuation, generation and smart structures

Abstract: Electroactive polymers (EAPs) can overcome many limitations of traditional smart material and transducer technologies. A particularly promising class of EAP is dielectric elastomer, also known as electroelastomer. Dielectric elastomer transducers are rubbery polymer materials with compliant electrodes that have a large electromechanical response to an applied electric field. The technology has been developed to the point where exceptional performance has already been demonstrated: for example, actuated strains of over 300 percent. These strains and the corresponding energy densities are beyond those of other field-activated materials including piezoelectrics. Because of their unique characteristics and expected low cost, dielectric elastomer transducers are under development in a wide range of applications including multifunctional (combined actuation, structure, and sensing) muscle-like actuators for biomimetic robots; microelectromechanical systems (MEMS); smart skins; conformal loudspeakers; haptic displays; and replacements for electromagnetic and pneumatic actuators for industrial and commercial applications. Dielectric elastomers have shown unique performance in each of these applications; however, some further development is required before they can be integrated into products and smart-materials systems. Among the many issues that may ultimately determine the success or failure of the technology for specific applications are durability, operating voltage and power requirements, and the size, cost, and complexity of the required electronic driving circuitry.

A role for cryptochromes in sleep regulation.

Abstract: Background The cryptochrome 1 and 2 genes (cry1 and cry2) are necessary for the generation of circadian rhythms, as mice lacking both of these genes (cry1,2-/-) lack circadian rhythms. We studied sleep in cry1,2-/- mice under baseline conditions as well as under conditions of constant darkness and enforced wakefulness to determine whether cryptochromes influence sleep regulatory processes.

Heritability of lobar brain volumes in twins supports genetic models of cerebral laterality and handedness

Abstract: Although the left and right human cerebral hemispheres differ both functionally and anatomically, little is known about the environmental or genetic factors that govern central nervous system asymmetry. Nevertheless, cerebral asymmetry is strongly correlated with handedness, and handedness does have a significant genetic component. To explore the relative contribution of environmental and genetic influences on cerebral asymmetry, we examined the volumes of left and right cerebral cortex in a large cohort of aging identical and fraternal twins and explored their relationship to handedness. Cerebral lobar volumes had a major genetic component, indicating that genes play a large role in changes in brain volume that occur with aging. Shared environment, which likely represents in utero events, had about twice the effect on the left hemisphere as on the right, consistent with less genetic control over the left hemisphere. To test the major genetic models of handedness and cerebral asymmetry, twin pairs were divided into those with two right handers and those with at least one left hander (nonright handers). Genetic factors contributed twice the influence to left and right cerebral hemispheric volumes in right-handed twin pairs, suggesting a large decrement in genetic control of cerebral volumes in the nonright-handed twin pairs. This loss of genetic determination of the left and right cerebral hemispheres in the nonright-handed twin pairs is consistent with models postulating a right-hand/left-hemisphere-biasing genetic influence, a “right-shift” genotype that is lost in nonright handers, resulting in decreased cerebral asymmetry.

A mission-impact-based approach to INFOSEC alarm correlation

Abstract: We describe a mission-impact-based approach to the analysis of security alerts produced by spatially distributed heterogeneous information security (INFOSEC) devices, such as firewalls, intrusion detection systems, authentication services, and antivirus software. The intent of this work is to deliver an automated capability to reduce the time and cost of managing multiple INFOSEC devices through a strategy of topology analysis, alert prioritization, and common attribute-based alert aggregation. Our efforts to date have led to the development of a prototype system called the EMERALD Mission Impact Intrusion Report Correlation System, or M-Correlator. M-Correlator is intended to provide analysts (at all experience levels) a powerful capability to automatically fuse together and isolate those INFOSEC alerts that represent the greatest threat to the health and security of their networks.

Sensor devices for structural health monitoring

Abstract: Described herein are wireless interrogation systems and methods that rely on a complementary sensing device and interrogator. The sensing device is disposed to measure a parameter indicative of the health of a structure. A sensor reading from the sensor indicates the level of a parameter being monitored or whether one or more particular physical or chemical events have taken place. Using wireless techniques, the interrogator probes the device to determine its identity and its current sensor reading. This often includes transmission of a wireless signal through portions of the structure. When activated, the device responds with a wireless signal that identifies the device and contains information about the parameter being measured or a particular sensor state corresponding to the parameter. The identity of the device allows it to be distinguished from a number of similar devices. Thus this invention finds particular usefulness in the context of an array of devices that can be probed by a wireless interrogation unit. In one embodiment, the devices are passive and derive power from the interrogation signal.

Method and apparatus for providing speech-driven routing between spoken language applications

Abstract: An apparatus and a concomitant method for speech recognition. In one embodiment, a distributed speech recognition system provides speech-driven control and remote service access. The distributed speech recognition system comprises a client device and a central server, where the client device is equipped with two speech recognition modules: a foreground speech recognizer and a background speech recognizer. The foreground speech recognizer is implementing a particular spoken language application (SLA) to handle a particular task, whereas the background speech recognizer is monitoring a change in the topic and/or a change in the intent of the user. Upon detection of a change in topic or intent of the user, the background speech recognizer will effect the routing to a new SLA to address the new topic or intent.

A mission-impact-based approach to INFOSEC alarm correlation

Abstract: We describe a mission-impact-based approach to the analysis of security alerts produced by spatially distributed heterogeneous information security (INFOSEC) devices, such as firewalls, intrusion detection systems, authentication services, and antivirus software. The intent of this work is to deliver an automated capability to reduce the time and cost of managing multiple INFOSEC devices through a strategy of topology analysis, alert prioritization, and common attribute-based alert aggregation. Our efforts to date have led to the development of a prototype system called the EMERALD Mission Impact Intrusion Report Correlation System, or M-Correlator. M-Correlator is intended to provide analysts (at all experience levels) a powerful capability to automatically fuse together and isolate those INFOSEC alerts that represent the greatest threat to the health and security of their networks.

Series of Abstractions for Hybrid Automata

Abstract: We present a technique based on the use of the quantifier elimination decision procedure for real closed fields and simple theorem proving to construct a series of successively finer qualitative abstractions of hybrid automata. The resulting abstractions are always discrete transition systems which can then be used by any traditional analysis tool. The constructed abstractions are conservative and can be used to establish safety properties of the original system. Our technique works on linear and non-linear polynomial hybrid systems, that is, the guards on discrete transitions and the continuous flows in all modes can be specified using arbitrary polynomial expressions over the continuous variables. We have a prototype tool in the SAL environment [13] which is built over the theorem prover PVS [19]. The technique promises to scale well to large and complex hybrid systems.

Preliminary evidence of reduced cognitive inhibition in methamphetamine-dependent individuals.

Abstract: a Abstract Chronic methamphetamine abuse is associated with disruption of frontostriatal function involving serotonin and dopamine circuitry. Clinically, methamphetamine-dependent (MD) individuals are highly distractible and have difficulty focussing. Here, we used a computerized single-trial version of the Stroop Test to examine selective attention and priming in MD. Subject groups comprised eight MD men (31.7"7.2 years of age), who had used methamphetamine for 15.75"8.4 years but were currently abstinent for 2-4 months, and 12 controls (35.7q9.7 years of age). Compared with the control group, the MD group exhibited significantly greater interference (P-0.05) despite intact priming. Error rates did not differ between the groups. This preliminary finding of reduced cognitive inhibition in MD individuals is consistent with the distractibility they show clinically. Furthermore, the dissociation between explicit attentional performance and priming effects suggests that some attentional functions are not as affected by long-term methamphetamine use as others. 2002 Elsevier Science Ireland Ltd. All rights reserved.

Variable stiffness electroactive polymer systems

Abstract: The invention relates to systems that provide variable stiffness and/or variable damping using an electroactive polymer transducer. Systems described herein offer several techniques that provide variable and controlled stiffness and/or damping. A transducer may be implemented using open loop control, thereby providing simple systems that inactively deliver a desired stiffness and/or damping performance. Alternately, closed loop control techniques permit electroactive polymer transducer designs that actively adapt the stiffness and/or damping performance of a system. Further, transducers may be implemented in a device whose stiffness changes with deflection of the polymer.

Parent-child interactions when young children have disabilities

Abstract: Publisher Summary This chapter discusses parent–child interactions for young children with disabilities. A major focus of the research on parent–child interactions has been to document what characteristics of parental interactive behavior promote and enhance child developmental outcomes, both short term and long term. The primary focus in this chapter is on the studies with children with disabilities or those at risk for developmental delay. Some of the literature based on the samples of children, who are typically developing, is also included in the discussion to highlight the major themes and issues and to provide comparison groups. The chapter describes selected studies with five populations of children, those with: (a) Down syndrome or mental retardation, (b) developmental delay, (c) orthopedic or motor impairments or cerebral palsy, (d) autism, and (e) low birth weight. Also, the focus is on the studies of behavioral interactions but not on parenting beliefs or attitudes. The chapter concludes with a brief discussion of intervention studies with young children with disabilities or delays aimed at promoting positive parent–child interactions.

A direction‐dependent instability of sporadic‐E layers in the nighttime midlatitude ionosphere

Abstract: [1] The configuration of a midlatitude sporadic-E (Es) layer at a zonal wind-shear node has been assumed to be a stable equilibrium, as long as the wind shear is hydrodynamically stable In this paper, we show that this equilibrium is in fact unstable, at night, to electrodynamical forces that arise when plane wave perturbations in altitude or density are imposed on the Es layer We show that the growth rate of the instability depends on the azimuthal alignment of the phase fronts of the plane-wave distortion, a feature that is reminiscient of the Perkins instability [Perkins, 1973] The dependence on azimuth is consistent with observations of structure in Es layers that show the same preferred alignment