Objectives/Hypothesis Characterizing the vertical stiffness gradient that exists between the superior and inferior aspects of the medial surface of the vocal fold. Characterization of this stiffness gradient could elucidate the mechanism behind the divergent glottal shape observed during closing. Study Design Basic science. Methods Indentation testing of the folds was done in a canine model. Stress-strain curves are generated using a customized load-cell and the differential Young's modulus is calculated as a function of strain. Results Results from 11 larynges show that stress increases as a function of strain more rapidly in the inferior aspect of the fold. The calculations for local Young's modulus show that at high strain values a stiffness gradient is formed between the superior and inferior aspects of the fold. Conclusions For small strain values, which are observed at low subglottal pressures, the stiffness of the tissue is similar in both the superior and inferior aspects of the vocal fold. Consequently, the lateral force that is applied by the glottal flow at both aspects results in almost identical displacements, yielding no divergence angle. Conversely, at higher strain values, which are measured in high subglottal pressure, the inferior aspect of the vocal fold is much stiffer than the superior edge; thus any lateral force that is applied at both aspects will result in a much greater displacement of the superior edge, yielding a large divergence angle. The increased stiffness observed at the inferior edge could be due to the proximity of the conus elasticus.

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Objective During phonation, skewing of the glottal flow waveform (Q) during phonation refers to a phenomenon that occurs when the flow decelerates more rapidly than it accelerates. This skewing is clinically important because it increases the glottal efficiency, which is defined by the acoustic intensity (units are sound pressure level or SPL) divided by the subglottal pressure. Current theoretical models predict that the only mechanism to cause skewing of Q involves changes in the vocal tract inertance. The purpose of the current work is to show that other factors at the vocal fold level can also cause skewing of Q and to determine if the acoustic intensity is correlated with MFDR. Study design Basic Science Methods Intraglottal geometry and velocity measurements were taken in five canine larynges at the mid-membranous plane using two-dimensional particle imaging velocimetry (PIV). The flow rate at the glottal exit was computed from the PIV measurements for low, medium, and high subglottal pressures. Results Vortices form in the superior aspect of the divergent glottis during closing. These vortices produce negative pressure that increases both the maximum value of Q and the rapid deceleration of the flow. The skewing of the flow rate is increased as the intraglottal vortices are increased by increasing the subglottal pressure. The increase in the acoustic intensity is highly correlated with certain properties of the flow rate waveform, such as maximum flow rate. Conclusion Flow skewing and the acoustic intensity can be increased by increasing the intraglottal vortices.

Purpose Despite increasing female representation in integrated plastic surgery training programs, independent programs have lower representation and slow improvement in female enrollment. Self-reported resident data were used to investigate trends of female representation in integrated and independent programs. Methods Data were collected from Accreditation Council of Graduate Medical Education resources of active residents' characteristics. Self-reported gender data were collected for integrated, independent, and general surgery programs from annual reports since 2009. χ2 analysis was conducted to compare female enrollment of integrated programs, independent programs, general surgery programs, and general surgery programs with matriculation-year adjustment. Results In 2008, 89 independent programs had nearly identical percentage of female enrollment with 30 integrated programs at 23.8% and 23.1%, respectively. Differences in representation between independent and integrated programs became significant in 2012, with independent programs demonstrating 25.1% female enrollment compared with 30.5% in integrated programs. This trend of higher female representation in integrated programs has persisted since 2012. To correct for preexisting disparity in general surgery programs, we compared female enrollment of independent programs with female enrollment of that class' general surgery matriculation-year 5 years earlier. In all examined years, general surgery still had proportionally higher female enrollment compared with independent programs, even with conservative 5-year matriculation adjustment. Conclusions Dramatic differences in female enrollment were found between integrated and independent programs, with representation in integrated programs rising more quickly. Adjustments for previous rates of female enrollment in general surgery did not yield explanation for low independent program enrollment. Increasing female representation in independent training models will continue to create a more diverse workforce.