Showing papers by "SRI International published in 1998"

Electrostriction of polymer dielectrics with compliant electrodes as a means of actuation

Abstract: The electrostriction of elastomeric polymer dielectrics with compliant electrodes is potentially useful as a small-scale, solid-state actuator technology. Electrostrictive polymer (EP) materials are capable of efficient and fast response with high strains (> 30%), good actuation pressures (up to 1.9 MPa), and high specific energy densities (up to 0.1 J g−1). In this article, the mechanism of electrostriction is shown to be due to the electrostatic attraction of free charges on the electrodes. Although EP actuators are electrostatics based, they are shown to produce 5–20 times the effective actuation pressure of conventional air-gap electrostatics at the same electric field strength. The thin uniform dielectric films necessary for fabrication of EP actuators have been fabricated by techniques such as spin coating, casting, and dipping. A variety of materials and techniques have been used to produce the compliant electrodes, including lift-off stenciling techniques for powdered graphite, selective wetting of ionically conductive polymers, and spray coating of carbon blacks and fibrils in polymeric binders. Prototype actuators have been demonstrated in a variety of configurations such as stretched films, stacks, rolls, tubes, and unimorphs. Potential applications of the technology in areas such as microrobots, sound generators, and displays are discussed in this article.

Generalizing data to provide anonymity when disclosing information (abstract)

Abstract: The proliferation of information on the Internet and access to fast computers with large storage capacities has increased the volume of information collected and disseminated about individuals. The existence os these other data sources makes it much easier to re-identify individuals whose private information is released in data believed to be anonymous. At the same time, increasing demands are made on organizations to release individualized data rather than aggregate statistical information. Even when explicit identi ers, such as name and phone number, are removed or encrypted when releasing individualized data, other characteristic data, which we term quasi-identi ers, can exist which allow the data recipient to re-identify individuals to whom the data refer. In this paper, we provide a computational disclosure technique for releasing information from a private table such that the identity of any individual to whom the released data refer cannot be de nitively recognized. Our approach protects against linking to other data. It is based on the concepts of generalization, by which stored values can be replaced with semantically consistent and truthful but less precise alternatives, and of k-anonymity . A table is said to provide k-anonymity when the contained data do not allow the recipient to associate the released information to a set of individuals smaller than k. We introduce the notions of generalized table and of minimal generalization of a table with respect to a k-anonymity requirement. As an optimization problem, the objective is to minimally distort the data while providing adequate protection. We describe an algorithm that, given a table, e ciently computes a preferred minimal generalization to provide anonymity.

Apparatus and method for performing computer enhanced surgery with articulated instrument

Abstract: A teleoperator system with telepresence is shown which includes right and left hand controllers (72R and 72L) for control of right and left manipulators (24R and 24) through use of a servomechanism that includes computer (42). Cameras (46R and 46L) view workspace (30) from different angles for production of stereoscopic signal outputs at lines (48R and 48L). In response to the camera outputs a 3-dimensional top-to-bottom inverted image (30I) is produced which, is reflected by mirror (66) toward the eyes of operator (18). A virtual image (30V) is produced adjacent control arms (76R and 76L) which is viewed by operator (18) looking in the direction of the control arms. By locating the workspace image (30V) adjacent the control arms (76R and 76L) the operator is provided with a sense that end effectors (40R and 40L) carried by manipulator arms (34R and 34L) and control arms (76R and 76L) are substantially integral. This sense of connection between the control arms (76R and 76L) and end effectors (40R and 40L) provide the operator with the sensation of directly controlling the and effectors by hand. By locating visual display (246) adjacent control arms (244R and 244L) image (240I) of the workspace is directly viewable by the operator. Use of the teleoperator system for surgical procedures also is disclosed.

Methods and devices for positioning a surgical instrument at a surgical site

Abstract: For positioning a surgical instrument at a surgical site, an elongate tubular structure is coupled to the distal portion of a robotic arm. This structure is adapted to be inserted in the body cavity of a patient and is adapted to receive the surgical instrument and serve as a guide for the surgical instrument into the patient's body. The robotic arm may have a parallelogram center of motion linkage and actuators for driving various degrees of freedom of movement of the arm and the surgical instrument. The robotic arm may be remotely controlled by an operator manipulating an input device.

Association of midlife blood pressure to late-life cognitive decline and brain morphology

Abstract: Objective: To investigate the association between midlife systolic blood pressure (SBP) and late-life cognitive decline and brain morphology in a sample of community-dwelling elderly men 68 to 79 years of age. Methods: Subjects are surviving members from the prospective National Heart, Lung, and Blood Institute Twin Study (intake, 1969 to 1972) who, when examined for a fourth time in 1995 through 1997, underwent brain MRI and repeated assessment of neurobehavioral functioning. Quantification of the MR images determined cerebral volume and total volume of white matter hyperintensities (WMHIs) for 392 subjects. Midlife SBP levels measured in 1970, 1980, and 1985 were used to classify subjects into low, medium, and high midlife SBP categories. A 10-year change in performance on the Mini-Mental State Examination, Digit Symbol Substitution Test, Benton Visual Retention Test, and Verbal Fluency Test was also calculated for these subjects. For all reported analyses, patients were treated as genetically unrelated individuals. Results: Subjects with high midlife SBP experienced a greater decline in cognitive performance and had larger WMHI volumes at follow-up in late life than did those with low midlife SBP. Decreased brain parenchyma and increased WMHI volumes were associated with decline in neurobehavioral functioning as measured in late life independent of age, education, and baseline levels of cognition. Conclusions: Midlife SBP is a significant predictor of both decline in cognitive function and MR volumetric measures of brain atrophy in late life. Because decline in neurobehavioral functioning was associated with decreased brain volume and increased WMHI volume, we conclude that the long-term impact of elevated SBP on decline in late-life neurobehavioral functioning is likely to be mediated through its chronic, negative effect on structural characteristics of the brain.

Evidence For Genetic Variance in White Matter Hyperintensity Volume in Normal Elderly Male Twins

Abstract: Background and Purpose—White matter hyperintensities (WMHs), as detected by MRI, are common among the elderly and are frequently interpreted as representing a subclinical form of ischemic brain damage. We used volumetric MR techniques to investigate the contribution of genes and the environment to measures of brain morphology in a sample of community dwelling elderly male twins. Methods—Brain MR (1.5 T) scans were obtained from 74 monozygotic (MZ) and 71 dizygotic (DZ), white, male, World War II veteran twins born in the United States and age 68 to 79 when scanned. MR quantification used a previously published semiautomated segmentation algorithm to segment brain images into total brain, cerebrospinal fluid (CSF), and WMH volumes. Twin pair covariances were computed for each measure, and structural equation genetic models were fitted to these data. Results—Total cranial, brain parenchyma, CSF, and WMH volumes were highly correlated in MZ pairs, and correlations in MZ pairs were significantly greater than ...

Multimodal Maps: An Agent-Based Approach

Abstract: In this paper, we discuss how multiple input modalities may be combined to produce more natural user interfaces. To illustrate this technique, we present a prototype map-based application for a travel planning domain. The application is distinguished by a synergistic combination of handwriting, gesture and speech modalities; access to existing data sources including the World Wide Web; and a mobile handheld interface. To implement the described application, a hierarchical distributed network of heterogeneous software agents was augmented by appropriate functionality for developing synergistic multimodal applications.

Family Outcomes in Early Intervention: A Framework for Program Evaluation and Efficacy Research:

Abstract: Much of the focus on the relationship between parents and professionals in early intervention has been on the rationale for working with families and the processes by which that rationale should be implemented. Although some discussion has occurred regarding desired outcomes, approaches and strategies by which the attainment of family outcomes could be documented have not been widely discussed or agreed upon by the field. In this article we suggest eight questions that could serve as a framework for determining the extent to which early intervention has accomplished the goals inherent in a family-centered approach. Conceptual issues and methodological considerations associated with documenting these outcomes are presented, and recommendations regarding implementation and future directions are made.

Can Prosody Aid the Automatic Classification of Dialog Acts in Conversational Speech

Abstract: Identifying whether an utterance is a statement, question, greeting, and so forth is integral to effective automatic understanding of natural dialog. Little is known, however, about how such dialog acts (DAs) can be automatically classified in truly natural conversation. This study asks whether current approaches, which use mainly word information, could be improved by adding prosodic information.The study is based on more than 1000 conversations from the Switchboard corpus. DAs were hand-annotated, and prosodic features (duration, pause, F0, energy, and speaking rate) were automatically extracted for each DA. In training, decision trees based on these features were inferred; trees were then applied to unseen test data to evaluate performance. Performance was evaluated for prosody models alone, and after combining the prosody models with word information—either from true words or from the output of an automatic speech recognizer.For an overall classification task, as well as three subtasks, prosody made s...

Electrostrictive polymer artificial muscle actuators

Abstract: Many new robotic and teleoperated applications require a high degree of mobility or dexterity that is difficult to achieve with current actuator technology. Natural muscle is an actuator that has many features, including high energy density, fast speed of response, and large stroke, that are desirable for such applications. The electrostriction of polymer dielectrics with compliant electrodes can be used in electrically controllable, muscle-like actuators. These electrostrictive polymer artificial muscle (EPAM) actuators can produce strains of up to 30% and pressures of up to 1.9 MPa. The measured specific energy achieved with polyurethane and silicone polymers exceeds that of electromagnetic, electrostatic, piezoelectric, and magnetostrictive actuators. A simple model using linear elastic theory can predict EPAM actuator performance from mechanical and electrical material properties and load conditions. A spherical joint for a highly articulated (snake-like) manipulator using EPAM actuator elements has been demonstrated. A rotary motor using EPAM actuator elements has been shown to produce a specific torque of 19 mNm/g and a specific power of 0.1 W/g. An improved EPAM motor could produce greater specific power and specific torque than could electric motors.

Molecular determinants of AHPN (CD437)-induced growth arrest and apoptosis in human lung cancer cell lines.

Abstract: 6-[3-(1-Adamantyl)-4-hydroxyphenyl]-2-naphthalene carboxylic acid (AHPN or CD437), originally identified as a retinoic acid receptor gamma-selective retinoid, was previously shown to induce growth inhibition and apoptosis in human breast cancer cells. In this study, we investigated the role of AHPN/CD437 and its mechanism of action in human lung cancer cell lines. Our results demonstrated that AHPN/CD437 effectively inhibited lung cancer cell growth by inducing G0/G1 arrest and apoptosis, a process that is accompanied by rapid induction of c-Jun, nur77, and p21(WAF1/CIP1). In addition, we found that expression of p53 and Bcl-2 was differentially regulated by AHPN/CD437 in different lung cancer cell lines and may play a role in regulating AHPN/CD437-induced apoptotic process. On constitutive expression of the c-JunAla(63,73) protein, a dominant-negative inhibitor of c-Jun, in A549 cells, nur77 expression and apoptosis induction by AHPN/CD437 were impaired, whereas p21(WAF1/CIP1) induction and G0/G1 arrest were not affected. Furthermore, overexpression of antisense nur77 RNA in A549 and H460 lung cancer cell lines largely inhibited AHPN/CD437-induced apoptosis. Thus, expression of c-Jun and nur77 plays a critical role in AHPN/CD437-induced apoptosis. Together, our results reveal a novel pathway for retinoid-induced apoptosis and suggest that AHPN/CD437 or analogs may have a better therapeutic efficacy against lung cancer.

Modeling dynamic prosodic variation for speaker verification.

Abstract: Statistics of frame-level pitch have recently been used in speaker recognition systems with good results [1, 2, 3]. Although they convey useful long-term information about a speaker’s distribution of f0 values, such statistics fail to capture information about local dynamics in intonation that characterize an individual’s speaking style. In this work, we take a first step toward capturing such suprasegmental patterns for automatic speaker verification. Specifically, we model the speaker’s f0 movements by fitting a piecewise linear model to the f0 track to obtain a stylized f0 contour. Parameters of the model are then used as statistical features for speaker verification. We report results on 1998 NIST speaker verification evaluation. Prosody modeling improves the verification performance of a cepstrum-based Gaussian mixture model system (as measured by a task-specific Bayes risk) by 10%.

Learning Bayesian networks with local structure

Abstract: In this paper we examine a novel addition to the known methods for learning Bayesian networks from data that improves the quality of the learned networks. Our approach explicitly represents and learns the local structure in the conditional probability tables (CPTs), that quantify these networks. This increases the space of possible models, enabling the representation of CPTs with a variable number of parameters that depends on the learned local structures. The resulting learning procedure is capable of inducing models that better emulate the real complexity of the interactions present in the data. We describe the theoretical foundations and practical aspects of learning local structures, as well as an empirical evaluation of the proposed method. This evaluation indicates that learning curves characterizing the procedure that exploits the local structure converge faster than these of the standard procedure. Our results also show that networks learned with local structure tend to be more complex (in terms of arcs), yet require less parameters.

Background modeling for segmentation of video-rate stereo sequences

Abstract: Stereo sequences promise to be a powerful method for segmenting images for applications such as tracking human figures. We present a method of statistical background modeling for stereo sequences that improves the reliability and sensitivity of segmentation in the presence of object clutter. The dynamic version of the method, called gated background adaptation, can reliably learn background statistics in the presence of corrupting foreground motion. The method has been used with a simple head discriminator to detect and track people using a stereo head mounted on a pan/tilt platform. It runs at video rates using standard PC hardware.

Midlife cardiovascular risk factors, ApoE, and cognitive decline in elderly male twins

Abstract: Objective To investigate the combined effect of the apolipoprotein E �4 (ApoE94) allele and midlife cardiovascular risk factors on cognitive decline. Methods Data are from the National Heart, Lung, and Blood Institute Twin Study-a longitudinal cardiovascular epidemiologic study of World War I1 male veteran twins currently in its 27th year of follow-up. Subjects were assessed for cardiovascular risk factors, including BP and glucose levels, at mean ages 48, 58, and 63 years. Participants in the current study are 410 individual twin subjects for whom cognitive function was measured twice, at ages 63 and 73 years. Ten-year change scores in performance on neuropsychological test examinations were adjusted for age, education, baseline score, and incident cardiovascular disease. Results For the sample as a whole, we observed a significant decline ( p Conclusions ApoE94 and midlife cardiovascular risk factors may have a synergistic effect on decline in cognitive function. This effect may be due to greater vascular or degenerative damage among subjects with ApoE94. NEUROLOGY 1998;50:1580–1585

Sequence alterations using homologous recombination

Abstract: The invention relates to methods for targeting an exogenous polynucleotide or exogenous complementary polynucleotide pair to a predetermined endogenous DNA target sequence in a target cell by homologous pairing, particularly for altering an endogenous DNA sequence, such as a chromosomal DNA sequence, typically by targeted homologous recombination. In certain embodiments, the invention relates to methods for targeting an exogenous polynucleotide having a linked chemical substituent to a predetermined endogenous DNA sequence in a metabolically active target cell, generating a DNA sequence-specific targeting of one or more chemical substituents in an intact nucleus of a metabolically active target cell, generally for purposes of altering a predetermined endogenous DNA sequence in the cell. The invention also relates to compositions that contain exogenous targeting polynucleotides, complementary pairs of exogenous targeting polynucleotides, chemical substituents of such polynucleotides, and recombinase proteins used in the methods of the invention.

From safety analysis to software requirements

Abstract: Software for safety critical systems must deal with the hazards identified by safety analysis. This paper investigates, how the results of one safety analysis technique, fault trees, are interpreted as software safety requirements to be used in the program design process. We propose that fault tree analysis and program development use the same system model. This model is formalized in a real-time, interval logic, based on a conventional dynamic systems model with state evolving over time. Fault trees are interpreted as temporal formulas, and it is shown how such formulas can be used for deriving safety requirements for software components.

Up-converting reporters for biological and other assays

Abstract: The invention provides methods, compositions, and apparatus for performing sensitive detection of analytes, such as biological macromolecules and other analytes, by labeling a probe molecule with an up-converting label The up-converting label absorbs radiation from an illumination source and emits radiation at one or more higher frequencies, providing enhanced signal-to-noise ratio and the essential elimination of background sample autofluorescence The methods, compositions, and apparatus are suitable for the sensitive detection of multiple analytes and for various clinical and environmental sampling techniques

Proton Magnetic Resonance Spectroscopic Imaging of Cortical Gray and White Matter in Schizophrenia

Abstract: Objective To apply in vivo proton magnetic resonance spectroscopy imaging estimates of N -acetylaspartate (NAA), a neuronal marker, to clarify the relative contribution of neuronal and glial changes to the widespread volume deficit of cortical gray matter seen in patients with schizophrenia with magnetic resonance images. Methods Ten male veterans meeting criteria of the DSM-IV, for schizophrenia and 9 healthy age-matched men for comparison were scanned using spectroscopic, anatomical, and field-map sequences. Instrument and collection variables were standardized to allow an estimation of comparable values for NAA, choline, and creatine for all subjects. Metabolite values from each voxel on 3 upper cortical slices were regressed against the gray tissue proportion of that voxel to derive estimates of gray and white matter NAA, creatine, and choline concentrations. Results The volume of cortical gray matter was reduced in patients with schizophrenia, but NAA signal intensity from a comparable region was normal. In contrast, the volume of cortical white matter was normal in patients with schizophrenia, but NAA signal intensity from a comparable region was reduced. Conclusions The lack of reduction in gray matter NAA signal intensity suggests that the cortical gray matter deficit in these patients involved both neuronal and glial compartments rather than a neurodegenerative process in which there is a decrease in the neuronal relative to the glial compartment. Reduced white matter NAA signal intensity without a white matter volume deficit may reflect abnormal axonal connections.

Ion battery using high aspect ratio electrodes

Abstract: Electrodes for secondary (rechargeable) batteries are fabricated using active material particles such as flakes, fingers, projections, needles, threads, fibers, pods, hairs, ribbons and the like, which have an aspect ratio of at least 1:3:1. The high aspect ratio, in combination with relatively shallow discharge cycles, provides high power of at least 800 W/kg sustainable over at least ten seconds, high energy of at least 7 W-hr/kg, and a high cycle life of at least 250 cycles. Selection of parameters also provides power to energy ratios for high power, high energy batteries of at least 10. Preferred chemistries for the novel batteries include lithium ion, and preferred active materials include carbon, metal oxides and metal. Batteries including the novel technology can advantageously be used in electric vehicles, consumer electronics, electrical appliances, and industrial applications such as battery backup systems and switches.

A new deleted allele in the human cytochrome P450 2A6 (CYP2A6) gene found in individuals showing poor metabolic capacity to coumarin and (+)- cis-3,5-dimethyl-2-(3-pyridyl)thiazolidin-4-one hydrochloride (SM-12502)

Abstract: The S-oxidation of (+)-cis-3,5-dimethyl-2-(3-pyridyl)thiazolidin-4-one hydrochloride (SM-12502) and the 7-hydroxylation of coumarin are primarily catalyzed by cytochrome P450 2A6 (CYP2A6). The activities of SM-12502 S-oxidase and coumarin 7-hydroxylase were investigated with liver microsomes from 20

The SEEK (Sporadic‐E Experiment over Kyushu) Campaign

Abstract: The SEEK (Sporadic-E Experiment over Kyushu) campaign was conducted in late August 1996 from the southern region of Kyushu, Japan, to investigate the mechanism for the generation of quasi-periodic (QP) radar backscatter from field-aligned irregularities imbedded in nighttime sporadic-E (Es) layers. SEEK was designed to determine in-situ small-scale electrodynamical properties using two sounding rockets and large-scale dynamics and electrodynamics using ground-based sensors, which included a transportable radar and other radio and optical instruments deployed in the vicinity of the rocket range. It was observed by this campaign that Es layers existed in a convergent wind shear region, where large electric fields were induced and when active atmospheric gravity waves existed in the mesosphere. However, there was little evidence which positively supported the hypothesis that Es layers were deeply modulated in altitude.

A profile of cortical gray matter volume deficits characteristic of schizophrenia.

Abstract: Quantitative magnetic resonance imaging (MRI) studies from our laboratory have reported that patients with schizophrenia show a widespread cortical gray matter volume deficit, which is especially pronounced in the prefrontal and anterior superior temporal cortices. The present study compared two separate samples of schizophrenic patients -- 71 men from a Veterans Administration (VA) hospital and a sample of 57 severely ill men from a state hospital (SH) -- in an effort to test whether the pattern of brain volume abnormalities previously observed in VA schizophrenic patients can be generalized to other groups of schizophrenic patients. MRI-derived brain volumes of gray matter, white matter and sulcal cerebrospinal fluid (CSF) in six cortical regions, and CSF in the lateral and third ventricles were computed. All MRI volumes were adjusted for normal variation in head size and age and were expressed as standardized Z-scores, which also permitted structures of different sizes to be compared directly. The two schizophrenic groups displayed similar patterns of volume abnormalities: cortical gray matter but not white matter volume deficits that were widespread but especially notable in the prefrontal and temporal regions. The regional gray matter deficits in the SH group were generally greater than those in the VA group, particularly in the prefrontal and posterior superior temporal regions. Both schizophrenic groups had abnormally large volumes of the cortical sulci and lateral and third ventricles; however, the SH group showed greater enlargements, the most prominent occurring in the ventricles and temporal sulci. The overlapping patterns of cortical gray matter deficits in the two groups provide evidence for generality of this pattern of regional brain volume abnormalities in schizophrenia.

The role of precipitation losses in producing the rapid early recovery phase of the Great Magnetic Storm of February 1986

Abstract: The possible role of precipitation losses in eroding stormtime ring current is subject to debate. To explore this controversy, the recovery phase of the February 6–10, 1986, great magnetic storm is examined, when intense ion precipitation was observed at midlatitudes by NOAA-6 and DMSP satellites. This storm period is particularly interesting because the ring current exhibits distinctive two-phase decay as seen in the Dst index, the early rapid timescale decay corresponding to the intense ion precipitation period described above. Hamilton et al. [1988] concluded, from close agreement between the observed timescale for ring current decay and the theoretical timescale for O+ charge exchange loss, that rapid early recovery phase of this storm resulted from the charge exchange loss of high energy O+; the second and longer decay phase was equated with H+ charge exchange loss. A model of the ring current evolution during this great magnetic storm [Fok et al., 1995] failed to reproduce the observed ring current decay rates, a puzzling result because charge exchange losses were well represented in the ring current model and initial and boundary conditions were taken from the same data set used in the Hamilton et al. [1988] study. A simple energy balance calculation for the global ring current is carried out using (1) either an energy input predicted from upstream solar wind parameters or one calculated from the drift-loss model output, (2) collisional loss timescales extracted from the drift-loss model, and (3) precipitation losses estimated from NOAA-6 and DMSP observations. The energy balance model replicates the evolution of the ring current energy content derived from Active Magnetospheric Particle Tracer Explorers/Charge Composition Explorer (AMPTE/CCE) observations when ion precipitation losses are included and model energy input function is reduced to agree with predictions based upon upstream solar wind parameters. The O+ charge exchange losses and observed global precipitation losses were of equal magnitude in early recovery of the ring current during this great magnetic storm. Later longer decay timescales in the model resulted from a combination of O+ and H+ charge exchange losses; O+ charge exchange losses remained important throughout the model time interval. The present model produces agreement with the AMPTE/CCE estimates of ring current kinetic energy content versus time. Disagreement between the Dst* inferred from the AMPTE/CCE particle measurements and the observed Dst* is an interesting issue needing further explanation.

The common pattern specification language

Abstract: This paper describes the Common Pattern Specification Language (CPSL) that was developed during the TIPSTER program by a committee of researchers from the TIPSTER research sites. Many information extraction systems work by matching regular expressions over the lexical features of input symbols. CPSL was designed as a language for specifying such finite-state grammars for the purpose of specifying information extraction rules in a relatively system-independent way. The adoption of such a common language would enable the creation of shareable resources for the development of rule-based information extraction systems.