Aspects of Vowel Perception by Normal Hearing and Hearing Impaired Listeners.

The effect of durational differences on the identification of vowel tokens was studied using ten normal hearing and six hearing impaired subjects. Stimuli were synthetically generated and varied in duration of the steady state, durations of the initial and final transitions and F1/F2/F3 location. Listeners were required to identify the given vowel token from a set of ten possible alternatives. The results from the normal hearing group supported the established effects of duration on the perception of vowels. However, these effects were different depending on the frequency locations of F1/F2/F3. Further, changes in the duration of the initial transition had a greater effect than changes in the duration of the final transition. By way of comparison, the identification behavior of the normal hearing subjects was different from the identification behavior of hearing impaired subjects. In particular, the hearing impaired subjects\u27 behavior was idiosyncratic. Further, not only were the subjects different from each other the labelling performance was different within the same subjects across the different vowels. Thus, the effects of durational changes on vowel identification by normal hearing and hearing impaired listeners differs as a function of formant frequency structure. In addition, the effects of durational changes were dependent on the portion of the vowel that was manipulated. Finally, hearing impaired listeners were not like the normal hearing listeners, nor were they like each other. The results, then can be interpreted to indicate that vowel perception by normal hearing and hearing impaired listeners is a complex multi-cued phenomenon

The retrofitting of existing buildings for seismic criteria

Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2004.Includes bibliographical references (leaves 52-53).This thesis describes the process for retrofitting a building for seismic criteria. It explains the need for a new, performance-based design code to provide a range of acceptable building behavior. It then outlines the procedure for retrofitting a building. This procedure begins with acquiring information about the existing building and its surroundings. The building owner or client then needs to work with the design professional to establish an acceptable performance level, or rehabilitation objective. A rehabilitation method must then be selected that determines how the building should be analyzed. The analysis of the building, including suggested rehabilitation strategies, must then be performed. Once the analysis indicates that the building will perform to its prescribed performance level, the rehabilitation strategies must then be implemented. The thesis ends with a description of two buildings that have recently been retrofitted, or are in the processes of being retrofitted. It gives an overview of the selected rehabilitation strategies and the reasoning behind their selection.by Christa Besing.M.Eng

Sensory Communication

Contains table of contents for Section 2, an introduction, reports on nine research projects and a list of publications.National Institutes of Health Grant 5 R01 DC00117National Institutes of Health Grant 2 R01 DC00270National Institutes of Health Grant 1 P01 DC00361National Institutes of Health Grant 2 R01 DC00100National Institutes of Health Grant FV00428National Institutes of Health Grant 5 R01 DC00126U.S. Air Force - Office of Scientific Research Grant AFOSR 90-200U.S. Navy - Office of Naval Research Grant N00014-90-J-1935National Institutes of Health Grant 5 R29 DC0062

Circadian regulation of mouse suprachiasmatic nuclei neuronal states shapes responses to orexin.

This is the final version of the article. Available from Wiley via the DOI in this record.Our knowledge of how circadian and homeostatic brain circuits interact to temporally organize physiology and behavior is limited. Progress has been made with the determination that lateral hypothalamic orexin (OXA) neurons control arousal and appetitive states, while suprachiasmatic nuclei (SCN) neurons function as the master circadian clock. During the day, SCN neurons exhibit heterogeneity in spontaneous resting membrane potential (RMP), with some neurons becoming severely depolarized (hyperexcited) and ceasing to fire action potentials (APs), while other neurons rest at moderate RMP and fire APs. Intriguingly, the day phase is when the SCN clock is most readily influenced by arousal, but it is unclear if and how heterogeneity in the excitability state of SCN neurons shapes their response to arousal signals, such as OXA. In whole-cell recordings we show that during the day OXA recruits GABA-GABAAreceptor signaling to suppress the RMP of hyperexcited silent as well as moderately hyperpolarized AP-firing SCN neurons. In the AP-firing neurons, OXA hyperpolarized and silenced these SCN cells, while in the hyperexcited silent neurons OXA suppressed the RMP of these cells and evoked either AP-firing, depolarized low-amplitude membrane oscillations, or continued silence at a reduced RMP. These results demonstrate how the resting state of SCN neurons determines their response to OXA, and illustrate that the inhibitory action of this neurochemical correlate of arousal can trigger paradoxical AP firing.We thank the BBSRC (BB/L007665/1) and the Wellcome Trust (WT092319MA) for project grant funding to H.D.P and M.D.C.B

Waveforms of molecular oscillations reveal circadian timekeeping mechanisms

Circadian clocks play a pivotal role in orchestrating numerous physiological and developmental events. Waveform shapes of the oscillations of protein abundances can be informative about the underlying biochemical processes of circadian clocks. We derive a mathematical framework where waveforms do reveal hidden biochemical mechanisms of circadian timekeeping. We find that the cost of synthesizing proteins with particular waveforms can be substantially reduced by rhythmic protein half-lives over time, as supported by previous plant and mammalian data, as well as our own seedling experiment. We also find that previously-enigmatic, cyclic expression of positive arm components within the mammalian and insect clocks allows both a broad range of peak time differences between protein waveforms and the symmetries of the waveforms about the peak times. Such various peak-time differences may facilitate tissue-specific or developmental stage-specific multicellular processes. Our waveform-guided approach can be extended to various biological oscillators, including cell-cycle and synthetic genetic oscillators.Comment: Supplementary material is available at the journal websit

Sensory Communication

Contains table of contents for Section 2, an introduction, reports on ten research projects and a list of publications.National Institutes of Health Grant 5 R01 DC00117National Institutes of Health Grant 5 R01 DC00270National Institutes of Health Grant 5 P01 DC00361National Institutes of Health Grant 2 R01 DC00100National Institutes of Health Grant 7 R29 DC00428National Institutes of Health Grant 2 R01 DC00126U.S. Air Force - Office of Scientific Research Grant AFOSR 90-0200U.S. Navy - Office of Naval Research Grant N00014-90-J-1935National Institutes of Health Grant 5 R29 DC00625U.S. Navy - Office of Naval Research Grant N00014-91-J-145