Showing papers by "SRI International published in 2000"

High-Speed Electrically Actuated Elastomers with Strain Greater Than 100%

Abstract: Electrical actuators were made from films of dielectric elastomers (such as silicones) coated on both sides with compliant electrode material. When voltage was applied, the resulting electrostatic forces compressed the film in thickness and expanded it in area, producing strains up to 30 to 40%. It is now shown that prestraining the film further improves the performance of these devices. Actuated strains up to 117% were demonstrated with silicone elastomers, and up to 215% with acrylic elastomers using biaxially and uniaxially prestrained films. The strain, pressure, and response time of silicone exceeded those of natural muscle; specific energy densities greatly exceeded those of other field-actuated materials. Because the actuation mechanism is faster than in other high-strain electroactive polymers, this technology may be suitable for diverse applications.

The Ames Salmonella/microsome mutagenicity assay

Abstract: The Ames Salmonella/microsome mutagenicity assay (Salmonella test; Ames test) is a short-term bacterial reverse mutation assay specifically designed to detect a wide range of chemical substances that can produce genetic damage that leads to gene mutations. The test employs several histidine dependent Salmonella strains each carrying different mutations in various genes in the histidine operon. These mutations act as hot spots for mutagens that cause DNA damage via different mechanisms. When the Salmonella tester strains are grown on a minimal media agar plate containing a trace of histidine, only those bacteria that revert to histidine independence (his(+)) are able to form colonies. The number of spontaneously induced revertant colonies per plate is relatively constant. However, when a mutagen is added to the plate, the number of revertant colonies per plate is increased, usually in a dose-related manner. The Ames test is used world-wide as an initial screen to determine the mutagenic potential of new chemicals and drugs. The test is also used for submission of data to regulatory agencies for registration or acceptance of many chemicals, including drugs and biocides. International guidelines have been developed for use by corporations and testing laboratories to ensure uniformity of testing procedures. This review provides historical aspects of how the Ames was developed and detailed procedures for performing the test, including the design and interpretation of results.

Dialogue act modeling for automatic tagging and recognition of conversational speech

Abstract: We describe a statistical approach for modeling dialogue acts in conversational speech, i.e., speech-act-like units such as STATEMENT, QUESTION, BACKCHANNEL, AGREEMENT, DISAGREEMENT, and APOLOGY. Our model detects and predicts dialogue acts based on lexical, collocational, and prosodic cues, as well as on the discourse coherence of the dialogue act sequence. The dialogue model is based on treating the discourse structure of a conversation as a hidden Markov model and the individual dialogue acts as observations emanating from the model states. Constraints on the likely sequence of dialogue acts are modeled via a dialogue act n-gram. The statistical dialogue grammar is combined with word n-grams, decision trees, and neural networks modeling the idiosyncratic lexical and prosodic manifestations of each dialogue act. We develop a probabilistic integration of speech recognition with dialogue modeling, to improve both speech recognition and dialogue act classification accuracy. Models are trained and evaluated using a large hand-labeled database of 1,155 conversations from the Switchboard corpus of spontaneous human-to-human telephone speech. We achieved good dialogue act labeling accuracy (65% based on errorful, automatically recognized words and prosody, and 71% based on word transcripts, compared to a chance baseline accuracy of 35% and human accuracy of 84%) and a small reduction in word recognition error.

Changing how and what children learn in school with computer-based technologies.

Abstract: Schools today face ever-increasing demands in their attempts to ensure that students are well equipped to enter the workforce and navigate a complex world. Research indicates that computer technology can help support learning, and that it is especially useful in developing the higher-order skills of critical thinking, analysis, and scientific inquiry. But the mere presence of computers in the classroom does not ensure their effective use. Some computer applications have been shown to be more successful than others, and many factors influence how well even the most promising applications are implemented. This article explores the various ways computer technology can be used to improve how and what children learn in the classroom. Several examples of computer-based applications are highlighted to illustrate ways technology can enhance how children learn by supporting four fundamental characteristics of learning: (1) active engagement, (2) participation in groups, (3) frequent interaction and feedback, and (4) connections to real-world contexts. Additional examples illustrate ways technology can expand what children learn by helping them to understand core concepts in subjects like math, science, and literacy. Research indicates, however, that the use of technology as an effective learning tool is more likely to take place when embedded in a broader education reform movement that includes improvements in teacher training, curriculum, student assessment, and a school's capacity for change. To help inform decisions about the future role of computers in the classroom, the authors conclude that further research is needed to identify the uses that most effectively support learning and the conditions required for successful implementation.

Electroactive polymer devices

Abstract: The present invention relates to transducers, their use and fabrication. The transducers convert between mechanical and electrical energy. Some transducers of the present invention include a pre-strained polymer. The pre-strain improves the conversion between electrical and mechanical energy. The present invention also relates to devices including an electroactive polymer to convert between electrical and mechanical energy. The present invention further relates to compliant electrodes that conform to the shape of a polymer included in a transducer. The present invention provides methods for fabricating electromechanical devices including one or more electroactive polymers.

Age-related decline in brain white matter anisotropy measured with spatially corrected echo-planar diffusion tensor imaging.

Abstract: Echo planar (EP) diffusion tensor imaging (DTI) permits in vivo identification of the orientation and coherence of brain white matter tracts but suffers from field inhomogeneity-induced geometric distortion. To reduce spatial distortion, polynomial warping corrections were applied and the effects tested on measures of fractional anisotropy (FA) in the genu and splenium of corpus callosum. Implementation entailed spatially warping EP images obtained without diffusion weighting (b = 0) to long-echo T(2)-weighted fast spin echo images, collected for anatomical delineation, tissue segmentation, and coregistration with the diffusion images. Using the optimal warping procedure (third-order polynomial), the effects of age on FA and a quantitative measure of intervoxel coherence (C) in the genu, splenium, centrum semiovale, and frontal and parietal pericallosal white matter were examined in 31 healthy men (23-76 years). FA declined significantly with age in all regions except the splenium, whereas intervoxel coherence positively correlated with age in the genu. Magn Reson Med 44:259-268, 2000.

Information retrieval by natural language querying

Abstract: A natural language information querying system includes an indexing facility configured to automatically generate indices of updated textual sources based on one or more predefined grammars and a database coupled to the indexing facility to store the indices for subsequent searching.

High-Strain Actuator Materials Based on Dielectric Elastomers

Abstract: Dielectric elastomers are a new class of actuator materials that exhibit excellent performance. The principle of operation, as well as methods to fabricate and test these elastomers, is summarized here. The Figure is a sketch of an elastomer film (light gray) stretched on a frame (black) and patterned with an electrode (mid-gray). Upon applying a voltage, the active portion of the elastomer expands and the strain can easily be measured optically.

Mobile navigation of network-based electronic information using spoken input

Abstract: A system, method, and article of manufacture are provided for navigating an electronic data source by means of spoken language where a portion of the data link between a mobile information appliance of the user and the data source utilizes wireless communication. When a spoken input request is received from a user who is using the mobile information appliance, it is interpreted. The resulting interpretation of the request is thereupon used to automatically construct an operational navigation query to retrieve the desired information from one or more electronic network data sources, which is transmitted to the mobile information appliance.

Using a community of distributed electronic agents to support a highly mobile, ambient computing environment

Abstract: A highly mobile, ambient computing environment is disclosed for serving a knowledge worker away from the their desk The present invention allows a knowledge worker to get increased leverage from personal, networked, and interactive computing devices while in their car, airplane seat, or in a conference room with others An Open Agent Architecture is used to incorporate elements such as GPS agents, speech recognition, and opportunistic connectivity among meeting participants Communication and cooperation between agents are brokered by one or more facilitators, which are responsible for matching requests, from users and agents, with descriptions of the capabilities of other agents It is not generally required that a user or agent know the identities, locations, or number of other agents involved in satisfying a request, and relatively minimal effort is involved in incorporating new agents and “wrapping” legacy applications Extreme flexibility is achieved through an architecture organized around the declaration of capabilities by service-providing agents, the construction of arbitrarily complex goals by users and service-requesting agents, and the role of facilitators in delegating and coordinating the satisfaction of these goals, subject to advice and constraints that may accompany them

The EcoCyc and MetaCyc databases

Abstract: EcoCyc is an organism-specific Pathway/Genome Database that describes the metabolic and signal-transduction pathways of Escherichia coli, its enzymes, and-a new addition-its transport proteins. MetaCyc is a new metabolic-pathway database that describes pathways and enzymes of many different organisms, with a microbial focus. Both databases are queried using the Pathway Tools graphical user interface, which provides a wide variety of query operations and visualization tools. EcoCyc and MetaCyc are available at http://ecocyc.PangeaSystems.com/ecocyc/

Adaptive, Model-Based Monitoring for Cyber Attack Detection

Abstract: Inference methods for detecting attacks on information resources typically use signature analysis or statistical anomaly detection methods. The former have the advantage of attack specificity, but may not be able to generalize. The latter detect attacks probabilistically, allowing for generalization potential. However, they lack attack models and can potentially "learn" to consider an attack normal. Herein, we present a high-performance, adaptive, model-based technique for attack detection, using Bayes net technology to analyze bursts of traffic. Attack classes are embodied as model hypotheses, which are adaptively reinforced. This approach has the attractive features of both signature based and statistical techniques: model specificity, adaptability, and generalization potential. Our initial prototype sensor examines TCP headers and communicates in IDIP, delivering a complementary inference technique to an IDS sensor suite. The inference technique is itself suitable for sensor correlation.

Network-based alert management

Abstract: A method of managing alerts in a network including receiving alerts from network sensors, consolidating the alerts that are indicative of a common incident and generating output reflecting the consolidated alerts.

Navigating network-based electronic information using spoken input with multimodal error feedback

Abstract: A system, method, and article of manufacture are provided for navigating an electronic data source by means of spoken language When a spoken input request is received from a user, it is interpreted Additional input is solicited from the user in a modality different than the original request and used to refine the navigation query The resulting interpretation of the request is thereupon used to automatically construct an operational navigation query to retrieve the desired information from one or more electronic network data sources

Cerebellar volume decline in normal aging, alcoholism, and Korsakoff's syndrome: relation to ataxia.

Abstract: The authors used magnetic resonance imaging to measure gray and white matter volumes in cerebellar hemispheres and 4 vermian regions in 61 normal control (NC) men aged 23-72 years, 25 men with uncomplicated alcoholism (ALC), and 8 men and 1 woman with alcoholic Korsakoff s syndrome (KS). NC and ALC took quantitative gait and balance tests. Gray but not white matter volume declined with normal age in both hemispheres and anterior-superior vermis. ALC had gray but not white matter cerebellar hemisphere volume deficits, whereas KS had deficits in both tissue types. ALC and KS had gray and white matter volume deficits in anterior superior but not posterior inferior vermis. ALC had a 1 SD ataxia deficit, significantly and selectively correlated with white matter volume in anterior superior vermis. Regional distribution but not severity of cerebellar volume deficits is similar in alcoholic individuals whether or not complicated by KS and relates to ataxia.

In vivo detection and functional correlates of white matter microstructural disruption in chronic alcoholism.

Abstract: Background: Postmortem studies report degradation of brain white matter microstructure in chronic alcoholism, but until recently, in vivo neuroimaging could provide measurement only at a macrostructural level. The development of magnetic resonance diffusion tensor imaging (DTI) for clinical use offers a method for depicting and quantifying the diffusion properties of white matter expressed as intravoxel and intervoxel coherence of tracts and fibers. Methods: This study used DTI to examine the intravoxel coherence measured as fractional anisotropy (FA) and intervoxel coherence (C) of white matter tracts of the genu and splenium of the corpus callosum and of the centrum semiovale in 15 detoxified alcoholic men and 31 nonalcoholic control subjects. Exploratory correlational analyses examined the relationships between regional DTI measures and tests of attention and working memory in the alcoholic patients. Results: The alcoholic group had lower regional FA than the control group. C was lower in the alcoholics than controls in the splenium only. Working memory correlated positively with splenium FA, whereas attention correlated positively with genu C. Conclusions: These results provide in vivo evidence for disruption of white matter microstructure in alcoholism and suggest that interruption of white matter fiber coherence contributes to disturbance in attention and working memory in chronic alcoholism.

Accessing network-based electronic information through scripted online interfaces using spoken input

Abstract: A system, method, and article of manufacture are provided for navigating an electronic data source that has a scripted online interface by means of spoken input. When a spoken request is received from a user, it is interpreted. A navigation query is constructed based on the interpretation of the speech input and a template extracted by scraping an online scripted interface to the data source. The resulting interpretation of the request is thereupon used to automatically construct an operational navigation query to retrieve the desired information from one or more electronic network data sources, which is then transmitted to a client device of the user.

Longitudinal changes in cognition, gait, and balance in abstinent and relapsed alcoholic men: relationships to changes in brain structure.

Abstract: Chronic alcoholism is associated with cognitive and motor deficits, and there is evidence for reversibility with sobriety. Alcoholic men were examined after 1 month of sobriety and 2 to 12 months later with cognitive and motor tests and magnetic resonance imaging. In this naturalistic study, 20 alcoholic participants had abstained and 22 had resumed drinking at retesting. Abstainers sustained greater improvement than relapsers on tests of delayed recall of drawings, visuospatial function, attention, gait, and balance. Shrinkage in 3rd ventricle volume across all participants significantly correlated with improvement in nonverbal short-term memory. Additional brain structure-function relationships, most involving short-term memory, were observed when analyses were restricted to alcoholic men who had maintained complete abstinence, were light relapsers for at least 3 months, or had consumed no more than 10 drinks prior to follow-up testing. Thus, alcoholic men who maintain abstinence can show substantial functional improvement that is related to improvement in brain structure condition.

Ultrahigh strain response of field-actuated elastomeric polymers

Abstract: Extremely large strains were achieved with elastomeric polymer films that are subject to high electric fields. The films were coated on both sides with complaint electrode material. When voltage was applied, the film compressed in thickness and expanded in area. The strain response is dominated by the electrostatic forces produced by the charges on the compliant electrodes. Actuated strains up to 117% were demonstrated with silicone elastomers, and up to 215% with acrylic elastomers. A key to achieving these large strains is to introduce a high prestrain to the film. Specific energy densities were much greater than those of other field-actuated materials. Because the response is electrostatic in nature, the actuation mechanism is predicted to be fast. Response speeds in excess of 2000 Hz have ben demonstrated in silicones. Acrylic response speeds are more than an order of magnitude slower, although the reason for this difference is not yet known. Measurement of material viscoelastic and electrical properties predicts that high efficiencies (> 80%) may be achieved with efficient driver circuits. A variety of actuators, including electrooptical devices, diaphragm pumps, and muscle like linear actuators, have been demonstrated with these materials, suggesting that this technology is well suited to small-scale electromechanical devices and robots.

Hierarchical event monitoring and analysis

Abstract: A computer-automated method of hierarchical event monitoring and analysis within an enterprise network including deploying network monitors in the enterprise network, detecting, by the network monitors, suspicious network activity based on analysis of network traffic data selected from the following categories: {network packet data transfer commands, network packet data transfer errors, network packet data volume, network connection requests, network connection denials, error codes included in a network packet}, generating, by the monitors, reports of the suspicious activity, and automatically receiving and integrating the reports of suspicious activity, by one or more hierarchical monitors.

An ontology for biological function based on molecular interactions

Abstract: Motivations: A number of important bioinformatics computations involve computing with function: executing computational operations whose inputs or outputs are descriptions of the functions of biomolecules. Examples include performing functional queries to sequence and pathway databases, and determining functional equality to evaluate algorithms that predict function from sequence. A prerequisite to computing with function is the existence of an ontology that provides a structured semantic encoding of function. Functional bioinformatics is an emerging subfield of bioinformatics that is concerned with developing ontologies and algorithms for computing with biological function. Results: The article explores the notion of computing with function, and explains the importance of ontologies of function to bioinformatics. The functional ontology developed for the EcoCyc database is presented. This ontology can encode a diverse array of biochemical processes, including enzymatic reactions involving smallmolecule substrates and macromolecular substrates, signal-transduction processes, transport events, and mechanisms of regulation of gene expression. The ontology is validated through its use to express complex functional queries for the EcoCyc DB.