41 research outputs found

    Formalizing structured file services for the data storage and retrieval subsystem of the data management system for Spacestation Freedom

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    A brief example of the use of formal methods techniques in the specification of a software system is presented. The report is part of a larger effort targeted at defining a formal methods pilot project for NASA. One possible application domain that may be used to demonstrate the effective use of formal methods techniques within the NASA environment is presented. It is not intended to provide a tutorial on either formal methods techniques or the application being addressed. It should, however, provide an indication that the application being considered is suitable for a formal methods by showing how such a task may be started. The particular system being addressed is the Structured File Services (SFS), which is a part of the Data Storage and Retrieval Subsystem (DSAR), which in turn is part of the Data Management System (DMS) onboard Spacestation Freedom. This is a software system that is currently under development for NASA. An informal mathematical development is presented. Section 3 contains the same development using Penelope (23), an Ada specification and verification system. The complete text of the English version Software Requirements Specification (SRS) is reproduced in Appendix A

    Time-phase bispectral analysis.

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    Bispectral analysis, a technique based on high-order statistics, is extended to encompass time dependence for the case of coupled nonlinear oscillators. It is applicable to univariate as well as to multivariate data obtained, respectively, from one or more of the oscillators. It is demonstrated for a generic model of interacting systems whose basic units are the Poincaré oscillators. Their frequency and phase relationships are explored for different coupling strengths, both with and without Gaussian noise. The distinctions between additive linear or quadratic, and parametric (frequency modulated), interactions in the presence of noise are illustrated

    Differential At-Risk Pediatric Outcomes of Parental Sensitivity Based on Hearing Status

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    Purpose: The aim of this study was to investigate the role of parental sensitivity in language and neurocognitive outcomes in children who are deaf and/or hard of hearing (DHH). Method: Sixty-two parent–child dyads of children with normal hearing (NH) and 64 of children who are DHH (3–8 years) completed parent and child measures of inhibitory control/executive functioning and child measures of sentence comprehension and vocabulary. The dyads also participated in a video-recorded, free-play interaction that was coded for parental sensitivity. Results: There was no evidence of associations between parental sensitivity and inhibitory control or receptive language in children with NH. In contrast, parental sensitivity was related to children's inhibitory control and all language measures in children who are DHH. Moreover, inhibitory control significantly mediated the association between parental sensitivity and child language on the Clinical Evaluation of Language Fundamentals–Fifth Edition Following Directions subscale (6–8 years)/Clinical Evaluation of Language Fundamentals Preschool–Second Edition Concepts and Following Directions subscale (3–5 years). Follow-up analyses comparing subgroups of children who used hearing aids (n = 29) or cochlear implants (CIs; n = 35) revealed similar correlational trends, with the exception that parental sensitivity showed little relation to inhibitory control in the group of CI users. Conclusions: Parental sensitivity is associated with at-risk language outcomes and disturbances in inhibitory control in young children who are DHH. Compared to children with NH, children who are DHH may be more sensitive to parental behaviors and their effects on emerging inhibitory control and spoken language. Specifically, inhibitory control, when scaffolded by positive parental behaviors, may be critically important for robust language development in children who are DHH
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