Estimating bone conduction transfer functions using otoacoustic emissions

A technique for estimating the nonparametric bone conduction transfer function using distortion product otoacoustic emissions (DPOAEs) is presented. Individual transfer functions were obtained using DPOAEs recorded from a single ear of five normal-hearing adults. Repeatability of the technique was investigated by performing measurements on at least three dates. Functions were reasonably repeatable, and were unique to each individual as expected from subjective measurements. Input force and DPOAE measurements were made for each individual, and a model of the auditory periphery representative of an average person was employed. The technique is objective and requires only passive cooperation, but robust DPOAEs are needed and the measurement time can be onerous for a wide frequency band or fine frequency resolution. With appropriate adjustments to the model of the auditory periphery, the method could be applied with animal models.     

Quantitative capillary gas chromatographic analysis

Summary The attainment of precise quatitative analytical data using open-tubular (capillary) columns in standard, commercially available gas chromatographic instrumentation is demonstrated. Key elements in the design and proper utilization of the instrumentation are discussed. The function of the various sample introduction systems is elaborated and their quantitative performance demonstrated. The extra-column contribution to band-spreading is determined and the resultant data is used assessing the suitability of commercial instrumentation for highspeed capillary gas chromatography. The quantitative analysis of a sample containing some eleven components in less than thirty seconds is shown.Dedicated to Dr. L. S. Ettre on his sixtieth birthday.     

A study of valence band shake-up features of CO on Pt {100} using synchrotron radiation

A study of the shake-up features in the valence region of CO on Pt{100} is presented. The onset of these features is shown to be correlated with the excitation threshold for the Pt(4f) levels. A possible mechanism for the shake-up process is proposed in which the Pt(4f) hole results in excited states other than a single electron-hole state. Subsequently, the Pt(4f) hole decays via a direct recombination process resulting in the observed satellite features. The implications of such a shake-up process for photon-stimulated desorption (PSD) are also discussed.     

The routine use of selective gas chromatographic detectors

Summary The availability of gas chromatographic detectors selective for phosphorus, sulfur, nitrogen and halogens and the possibility of their simultaneous operation with each other or with conventional universal detectors has tremendously increased the amount of qualitative information that can be gathered from an unknown sample. Selective detectors when used simultaneously permit the calculation of percentage ratios of heteroatoms which represent additional information for qualitative identification. Combination of parallel columns with selective detectors reduces the total time needed for analysis and introduces additional information due to the different polarity of the columns.     

Kinetic study of the reaction betweentrans-tetracyanodioxorhenate(V) and thiocyanate ions

Transition Metal Chemistry - The kinetics of the reaction between NCS− and the diprotonated forms of [ReO2(CN)4]3− have been studied in theca. 1 to 3 pH range. This study showed that...     

Preparing for an art: the employment interview

Every chemist should become skillful in the art of the employment interview. Successful practice of this art requires particular preparation. The four “R's” lead to confidence in obtaining the position you want.     

Human temporal auditory acuity as assessed by envelope following responses

Temporal auditory acuity, the ability to discriminate rapid changes in the envelope of a sound, is essential for speech comprehension. Human envelope following responses (EFRs) recorded from scalp electrodes were evaluated as an objective measurement of temporal processing in the auditory nervous system. The temporal auditory acuity of older and younger participants was measured behaviorally using both gap and modulation detection tasks. These findings were then related to EFRs evoked by white noise that was amplitude modulated (25% modulation depth) with a sweep of modulation frequencies from 20 to 600 Hz. The frequency at which the EFR was no longer detectable was significantly correlated with behavioral measurements of gap detection (r = -0.43), and with the maximum perceptible modulation frequency (r = 0.72). The EFR techniques investigated here might be developed into a clinically useful objective estimate of temporal auditory acuity for subjects who cannot provide reliable behavioral responses.