An improved technique for the measurement of temperature distributions in an EHD conjunction is presented. The technique reported here employs the infrared radiation emitted by the EHD conjunction and appears more rigorous, more reliable, and less cumbersome than that reported previously by the authors. Detailed mapping of fluid temperature (averaged through the thickness) and the ball surface temperature can be obtained. These temperature distributions have been reported for a naphthenic mineral oil for peak Hertz pressures of 1.05 and 1.51 GN/m2 (148 and 219 kpsi), at sliding speeds ranging from 0.35 to 12.7 m/s (13.4 to 500 ips) and a bath temperature of 40°C.
This paper describes an experimental investigation of the elastohydrodynamic problem. The investigation was limited to a study of nominal point contacts in pure sliding motion. The profile of the lubricant film separating the bearing surfaces was determined during a transient of the normal load. During this transient the Hertzian contact stresses were increased from zero to a maximum of 150,000 lbf/in2 in approximately 45 milli-secs. The sliding velocities used in this study were varied from 13.7 to 92.1 ips. The resulting mean shear rate, however, was typically 107 reciprocal seconds. Both pure and polymer-blended naphthenic and paraffinic oils, in addition to several synthetic fluids, were studied. On the basis of the film thickness profiles obtained for the polymer-blended oils, it was concluded that the ambient value of viscosity often used in theoretical considerations does not characterize the behavior of the system. It was also found that the rapid application of the normal load had a negligible effect on the film thickness profile. During this investigation the contact traction was also measured. The results of those measurements are reported in the companion paper, “Fluid Rheological Effects in Sliding Elastohydrodynamic Point Contacts With Transient Loading: II—Traction.”
Background Procedural training is a required competency in internal medicine (IM) residency, yet limited data exist on residents’ experience of procedural training. Objectives We sought to understand how gender impacts access to procedural training among IM residents. Methods A mixed-methods, explanatory sequential study was performed. Procedure volume for IM residents between 2016 and 2020 was assessed at two large academic residencies (Program A and Program B: 399 residents and 4,020 procedures). Procedural rates and actual versus expected procedure volume by gender were compared, with separate analyses by clinical environment (intensive care unit [ICU] or structured procedural service). Semistructured gender-congruent focus groups were conducted. Topics included identity formation as a proceduralist and the resident procedural learning experience, including perceived gender bias in procedure allocation. Results Compared with men, women residents performed disproportionately fewer ICU procedures per month at Program A (1.4 vs. 2.7; P < 0.05) but not at Program B (0.36 vs. 0.54; P = 0.23). At Program A, women performed only 47% of ICU procedures, significantly fewer than the 54% they were expected to perform on the basis of their time on ICU rotations ( P < 0.001). For equal gender distribution of procedural volume at Program A, 11% of the procedures performed by men would have needed to have been performed by women instead. Gender was not associated with differences in the Program A structured procedural service (53% observed vs. 52% expected; P = 0.935), Program B structured procedural service (40% observed vs. 43% expected; P = 0.174), or in Program B ICUs (33% observed vs. 34% expected; P = 0.656). Focus group analysis identified that women from both residencies perceived that assertiveness was required for procedural training in unstructured learning environments. Residents felt that gender influenced access to procedural opportunities, ability to self-advocate for procedural experience, identity formation as a proceduralist, and confidence in acquiring procedural skills. Conclusion Gender disparities in access to procedural training during ICU rotations were seen at one institution but not another. There were ubiquitous perceptions that assertiveness was important to access procedural opportunities. We hypothesize that structured allocation of procedures would mitigate disparities by allowing all residents to access procedural training regardless of self-advocacy. Residency programs should adopt structured procedural training programs to counteract inequities.
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