Tone burst-evoked otoacoustic emissions in neonates: normative data

<p>Abstract</p> <p>Background</p> <p>Tone-burst otoacoustic emissions (TBOAEs) have not been routinely studied in pediatric populations, although tone burst stimuli have greater frequency specificity compared with click sound stimuli. The present study aimed (1) to determine an appropriate stimulus level for neonatal TBOAE measurements when the stimulus center frequency was 1 kHz, (2) to explore the characteristics of 1 kHz TBOAEs in a neonatal population.</p> <p>Methods</p> <p>A total of 395 normal neonates (745 ears) were recruited. The study consisted of two parts, reflecting the two study aims. Part I included 40 normal neonatal ears, and TBOAE measurement was performed at five stimulus levels in the range 60–80 dB peSPL, with 5 dB incremental steps. Part II investigated the characteristics of the 1 kHz TBOAE response in a large group of 705 neonatal ears, and provided clinical reference criteria based on these characteristics.</p> <p>Results</p> <p>The study provided a series of reference parameters for 1 kHz TBOAE measurement in neonates. Based on the results, a suggested stimulus level and reference criteria for 1 kHz TBOAE measures with neonates were established. In addition, time-frequency analysis of the data gave new insight into the energy distribution of the neonatal TBOAE response.</p> <p>Conclusion</p> <p>TBOAE measures may be a useful method for investigating cochlear function at specific frequency ranges in neonates. However, further studies of both TBOAE time-frequency analysis and measurements in newborns are needed.</p

Circuit-based interrogation of sleep control.

Sleep is a fundamental biological process observed widely in the animal kingdom, but the neural circuits generating sleep remain poorly understood. Understanding the brain mechanisms controlling sleep requires the identification of key neurons in the control circuits and mapping of their synaptic connections. Technical innovations over the past decade have greatly facilitated dissection of the sleep circuits. This has set the stage for understanding how a variety of environmental and physiological factors influence sleep. The ability to initiate and terminate sleep on command will also help us to elucidate its functions within and beyond the brain

The impact of scaling on hot-carrier degradation and supply voltage of deep-submicron NMOS transistors

\u3cp\u3eAn experimental study of hot carrier degradation and power supply voltage scaling of deep-submicron NMOS devices is presented. Devices were optimized for processes with design rule between 2 μ m and 0.17 μ m. Charge pumping measurements showed that the lifetime based on interface state generation in the devices was determined only by I\u3csub\u3esub\u3c/sub\u3e/I\u3csub\u3ed\u3c/sub\u3e and the drain current. It did not depend on gate length, oxide thickness, and substrate doping. The lifetime (determined by shifts in the maximum linear transconductance) of the devices with minimum gate length of different processes fall on a single life in plots of tau I\u3csub\u3ed\u3c/sub\u3e versus I\u3csub\u3esub\u3c/sub\u3e/I\u3csub\u3ed\u3c/sub\u3e. This behavior can be explained by the impact of interface damage on the transistor parameters of these devices. Light emission spectra and device simulation showed that nonlocal carrier heating becomes important for devices from deep-submicron processes. As a result the power supply voltage is almost independent of design rule for the deep-submicron process (V\u3csub\u3edd\u3c/sub\u3e&lt;or=2.5 V).\u3c/p\u3