The First Five Minutes: Enhancing Simulation Education for First-Year Pediatric Residents

We are looking at the feasibility of redesigning the existing simulation education for first-year residents within the Children’s Hospital of Richmond at VCU’s pediatric residency program to increase learning opportunities and to enhance exposure to pediatric medical emergencies. Novel simulation scenarios were designed to provide an introduction to managing the first five minutes of commonly encountered emergencies on the inpatient wards. These shortened simulations allow for educational objectives to be tailored to the expected knowledge and responsibilities of first-year residents

Development of freeze-thaw processing technique for disaggregation of indurated mudrocks and enhanced recovery of calcareous microfossils

Microfossil extraction from indurated mudrocks is widely acknowledged as challenging, especially for foraminifera. Here we report development of the freeze–thaw extraction method through the addition of rapid heating, detergent and ultrasound stages. We use indurated mudrock samples from the Toarcian (Early Jurassic) of Yorkshire, UK to assess the effectiveness and develop the freeze–thaw method. We compare our results from freeze–thaw with those from standard foraminifera processing techniques, including the use of hydrogen peroxide. Processing by freeze–thaw increased the degree of mudrock disaggregation and resulted in no damage or dissolution of foraminifera. Following the freeze–thaw method with treatment in white spirit and sodium hexametaphosphate aided the separation of foraminifera from the disaggregated clays and was twice as efficient as pressure washing. Samples processed with hydrogen peroxide contained damaged microfossils and an under representation of delicate calcareous foraminifera. Many other studies of indurated mudrocks have used hydrogen peroxide to extract foraminifera, and this might have resulted in apparently barren intervals. The freeze–thaw method outlined here provides a low-cost, low-risk and successful method of disaggregating and extracting calcareous microfossils from indurated mudrocks. We anticipate our method may be relevant for other fossil groups and merits further development

Effect of speed and press fit on fatigue life of roller-bearing inner-race contact

An analysis was performed to determine the effects of inner ring speed and press fit on the rolling element fatigue life of a roller bearing inner race contact. The effects of the resultant hoop and radial stresses on the principal stresses were considered. The maximum shear stresses below the Hertzian contact were determined for different conditions of inner ring speed, load, and geometry and were applied to a conventional ring life analysis. The race contact fatigue life was reduced by more than 90 percent for some conditions when speed and press fit were considered. The depth of the maximum shear stress remained virtually unchanged

Effect on interference fits on roller bearing fatigue life

An analysis was performed to determine the effects of inner-ring speed and press fits on roller bearing fatigue life. The effects of the resultant hoop and radial stresses on the principal stresses were considered. The maximum shear stresses below the Hertzian contact were determined for different conditions of inner-ring speed and load, and were applied to a conventional roller bearing life analysis. The effect of mean stress was determined using Goodman diagram approach. Hoop stresses caused by press fits and centrifugal force can reduce bearing life by as much as 90 percent. Use of a Goodman diagram predicts life reductions of 20 to 30 percent. The depth of the maximum shear stress remains virtually unchanged

Predicted and experimental performance of jet-lubricated 120-millimeter-bore ball bearings operating to 2.5 million DN

Bearing inner- and outer-race temperatures and friction power losses were calculated using two computer programs. The values obtained were compared with previously reported experimental data for 120 mm bore bearings which operated at thrust loads to 22 240 N (5000 lb), shaft speeds to 20 800 rpm, and with two lubricant flow rates. One program severely underestimated the power loss, while the other, called SHABERTH, provided a good prediction of both race temperatures and power losses

Analysis of stresses at the bore of a drilled ball operating in a high-speed bearing

Three-dimensional stress distributions were calculated for both a regular drilled ball with a stiffening web. The balls were 20.6 mm (0.8125 in.) in diameter and had a 12.6 mm (0.496 in.) diameter concentric hole. The stiffening web was 1.5 mm (0.06 in.) thick. The calculations showed that a large reversing tangential stress at the hole bore was reduced by one-half by the addition of the web

Lubrication and performance of high-speed rolling-element bearings

Trends in aircraft engine operating speeds have dictated the need for rolling-element bearings capable of speeds to 3 million DN. A review of high-speed rolling-element bearing state-of-the-art performance and lubrication is presented. Through the use of under-race lubrication and bearing thermal management bearing operation can be obtained to speeds of 3 million DN. Jet lubricated ball bearings are limited to 2.5 million DN for large bore sizes and to 3 million DN for small bore sizes. Current computer programs are able to predict bearing thermal performance

Solvable senescence model with positive mutations

We build upon our previous analytical results for the Penna model of senescence to include positive mutations. We investigate whether a small but non-zero positive mutation rate gives qualitatively different results to the traditional Penna model in which no positive mutations are considered. We find that the high-lifespan tail of the distribution is radically changed in structure, but that there is not much effect on the bulk of the population. Th e mortality plateau that we found previously for a stochastic generalization of the Penna model is stable to a small positive mutation rate.Comment: 3 figure

Monitoring and Discovering X-ray Pulsars in the Small Magellanic Cloud

Regular monitoring of the SMC with RXTE has revealed a huge number of X-ray pulsars. Together with discoveries from other satellites at least 45 SMC pulsars are now known. One of these sources, a pulsar with a period of approximately 7.8 seconds, was first detected in early 2002 and since discovery it has been found to be in outburst nine times. The outburst pattern clearly shows a period of 45.1 +/- 0.4 d which is thought to be the orbital period of this system. Candidate outburst periods have also been obtained for nine other pulsars and continued monitoring will enable us to confirm these. This large number of pulsars, all located at approximately the same distance, enables a wealth of comparative studies. In addition, the large number of pulsars found (which vastly exceeds the number expected simply by scaling the relative mass of the SMC and the Galaxy) reveals the recent star formation history of the SMC which has been influenced by encounters with both the LMC and the Galaxy.Comment: 5 pages, 4 figures, AIP conference proceedings format. Contribution to "X-ray Timing 2003: Rossi and Beyond." meeting held in Cambridge, MA, November, 200