Elizabethtown College is a small comprehensive college located in Elizabethtown, Pennsylvania, United States in Lancaster County. The school was founded in 1899 by members of the Church of the Brethren. It is commonly referred to as "E-town," and has a undergraduate student body population of approximately 2,000. Wikipedia.
Nifong T.P.,Metamark Genetics |
McDevitt T.J.,Elizabethtown College
Chest | Year: 2011
Background: Catheter-related thrombosis is a common complication in all anatomic sites, especially when smaller veins of the upper extremity are considered. It is presumed that the presence of a catheter within the lumen of a vein will decrease flow and potentially create stasis, and clinical data suggest that the size of the catheter impacts thrombosis rates. We sought to determine, both mathematically and experimentally, the impact of catheters on fluid flow rates. Methods: We used fluid mechanics to calculate relative flow rates as a function of the ratio of the catheter to vein diameters. We also measured the flow rate of a blood analyte solution in an annular flow model using diameters that simulate the size of upper extremity veins and commonly used peripherally inserted central catheters (PICCs). Results: We compared each of the derived relative flow rates to the experimentally determined ones for three cylinder sizes and found a correlation of r2 = 0.90. We also confirmed that the decrease in fluid flow rate with each successive catheter size is statistically significant (P<.0001). Conclusions: Our results demonstrate that fluid flow is dramatically decreased by the insertion of a centrally located obstruction. Assuming that blood flow in veins behaves in a similar manner to our models, PICCs, in particular, may substantially decrease venous flow rates by as much as 93%. © 2011 American College of Chest Physicians.
Martinez D.E.,Pomona College |
Bridge D.,Elizabethtown College
International Journal of Developmental Biology | Year: 2012
Existing data imply that the cnidarian Hydra vulgaris does not undergo senescence. In contrast, the related species Hydra oligactis shows increased mortality and physiological deterioration following sexual reproduction. Hydra thus offers the chance to study a striking difference in lifespan in members of the same genus. Adult Hydra possess three well-characterized stem cell populations, one of which gives rise to both somatic cells and gametes. The lack of senescence in Hydra vulgaris raises the question of how these stem cell populations are maintained over long periods of time. Investigation of the roles in Hydra of proteins involved in cellular stress responses in other organisms should provide insight into this issue. Proteins of particular interest include the Hsp70 family proteins and the transcription factor FoxO. © UBC Press.
McDevitt T.J.,Elizabethtown College
International Journal of Computer Mathematics | Year: 2012
Finite differences are frequently used to differentiate empirical functions, but standard differences tend to amplify the random error that is present in almost all empirical data. This paper uses higher-order Lanczos derivatives and discretized Legendre polynomials to generate minimum variance finite differences to approximate ordinary derivatives of all orders for a fixed discretization error magnitude. The resulting differences can be implemented as finite impulse response filters and are therefore very fast on a computer. © 2012 Taylor & Francis Group, LLC.
Johnson K.A.,Elizabethtown College
Learning, Media and Technology | Year: 2011
Greater numbers of instructors are turning to social networking sites to communicate with students. This study examined whether posting social, scholarly, or a combination of social and scholarly information to Twitter has an impact on the perceived credibility of the instructor. Participants were assigned to one of three groups: a group that viewed social tweets, one that viewed scholarly tweets, and one that viewed a combination of social and scholarly tweets. Participants were then asked questions about the instructor's perceived credibility. Results show that participants who viewed only the social tweets rated the instructor significantly higher in perceived credibility than the group that viewed only the scholarly tweets. No other significant differences were found among the groups. These results have implications for both teaching and learning, as there is an established link between perceived instructor credibility and positive learning outcomes. © 2011 Taylor & Francis.
O'hara K.D.,University of Kentucky |
Esawi E.K.,Elizabethtown College
GSA Today | Year: 2013
A physical model of the Old Faithful geyser successfully replicates the eruption interval for the years 2000-2011. It is based on convective boiling in the conduit in three stages, and the model is in good agreement with published time-temperature-depth data. The preplay phase, which triggers the main eruption, displays a Rayleigh probability density function with a mode at nine minutes, and it plays an essential role in determining the main eruption interval. It is assumed that temperature gradients are small due to convection, and individual convection cells can be assigned a single heat content. Based on previous observations and drill-hole measurements, the bottom heating and recharge temperatures are assumed to be 110 °C and 80 °C, respectively, and the total volume of the cylindrical conduit is 23 m3. A prescription for both short and long eruption intervals is eruption interval = (time to boiling of upper stage) + (preplay time). A composite model reproduces the bimodal eruption pattern in which long eruption durations are followed by long eruption intervals and short eruption durations are followed by short eruption intervals. The cause of short eruption durations is not addressed and remains unresolved.