1,940 research outputs found

    An Improved Implementation and Abstract Interface for Hybrid

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    Hybrid is a formal theory implemented in Isabelle/HOL that provides an interface for representing and reasoning about object languages using higher-order abstract syntax (HOAS). This interface is built around an HOAS variable-binding operator that is constructed definitionally from a de Bruijn index representation. In this paper we make a variety of improvements to Hybrid, culminating in an abstract interface that on one hand makes Hybrid a more mathematically satisfactory theory, and on the other hand has important practical benefits. We start with a modification of Hybrid's type of terms that better hides its implementation in terms of de Bruijn indices, by excluding at the type level terms with dangling indices. We present an improved set of definitions, and a series of new lemmas that provide a complete characterization of Hybrid's primitives in terms of properties stated at the HOAS level. Benefits of this new package include a new proof of adequacy and improvements to reasoning about object logics. Such proofs are carried out at the higher level with no involvement of the lower level de Bruijn syntax.Comment: In Proceedings LFMTP 2011, arXiv:1110.668

    Aerospace Medicine and Biology: A continuing bibliography with indexes, supplement 182, July 1978

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    This bibliography lists 165 reports, articles, and other documents introduced into the NASA scientific and technical information system in June 1978

    The Effect of Olivocochlear Bundle Transection on Cochlear Mechanics.

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    A growing body of research suggests that the efferent innervation to the cochlea, the olivocochlear bundle, plays a role in modulating the mechanical function of the cochlea. Some of the more provocative findings supporting an hypothesis of OCB modulation have come from studies which assessed efferent influences on tuning curves and acoustic distortion products, two measures thought to be sensitive indicators of cochlear mechanical function. While the OCB appears to be capable of modifying cochlear mechanics, the functional role attributed to the efferents has been difficult to define. For example, some studies which have transected all or part of the OCB have found changes in cochlear tuning, while others have not. Similarly, investigations which have electrically or acoustically stimulated the OCB have yielded contradictory findings. Particularly little is known about the role of tonic OCB input in cochlear function. The purpose of this project was to determine the influence of tonic efferent input on cochlear mechanics, by transecting the entire olivocochlear bundle (OCB) in guinea pigs, and observing changes in tuning curves and acoustic distortion products. The olivocochlear bundle was transected by avulsing the inferior vestibular nerve, as it enters the internal auditory canal of the right bulla. Auditory brainstem response (ABR) thresholds, ABR tuning curves, and acoustic distortion products were measured before and after surgery. Successful transection of the OCB was verified histochemically. Results revealed no consistent changes in tuning curves or in the growth functions of the acoustic distortion products. It was therefore concluded that tonic olivocochlear input is not necessary for normal cochlear mechanical function. It appears that the OCB normally exerts an influence on cochlear mechanics only when activated by sound. Possible roles for the OCB in the forward masking phenomenon were discussed, as well as a putative OCB role in reducing the auditory input to cochlear nucleus and higher centers, to improve central auditory processing

    Aerospace medicine and biology: A continuing bibliography with indexes, supplement 183

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    This bibliography lists 273 reports, articles, and other documents introduced into the NASA scientific and technical information system in July 1978

    Aerospace Medicine and Biology. A continuing bibliography with indexes

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    This bibliography lists 244 reports, articles, and other documents introduced into the NASA scientific and technical information system in February 1981. Aerospace medicine and aerobiology topics are included. Listings for physiological factors, astronaut performance, control theory, artificial intelligence, and cybernetics are included

    Aerospace Medicine and Biology: A continuing bibliography (supplement 160)

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    This bibliography lists 166 reports, articles, and other documents introduced into the NASA scientific and technical information system in October 1976

    Aerospace Medicine and Biology: A continuing bibliography with indexes, supplement 144

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    This bibliography lists 257 reports, articles, and other documents introduced into the NASA scientific and technical information system in July 1975
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