Mild traumatic brain injury among a cohort of rugby union players: predictors of time to injury
- Authors: Hollis, Stephanie , Stevenson, Mark , McIntosh, Andrew , Li, Ling , Heritier, Stephane , Shores, E Arthur , Collins, Michael , Finch, Caroline
- Date: 2011
- Type: Text , Journal article
- Relation: British Journal of Sports Medicine Vol. 45, no. 12 (2011), p. 997-999
- Full Text: false
- Reviewed:
- Description: This study reports the time to sustain a mild traumatic brain injury (mTBI) among a cohort of community rugby union players. Demographic and player characteristics were collected and players followed up for between one and three playing seasons. 7% of the cohort sustained an mTBI within 10 h of game time, increasing twofold to 14% within 20 h. The mean time to first mTBI was 8 h with an SD of 6.2 (median 6.8 h; IQR: 2.9–11.7 h). Players reporting a recent history of concussion were 20% more likely to sustain an mTBI after 20 h of game time compared with those with no recent history of concussion. Players were likely to sustain an mTBI in shorter time if they trained for <3 h/week (HR=1.48, p=0.03) or had a body mass index <27 (HR=1.77, p=0.007). The findings highlight modifiable characteristics to reduce the likelihood of shortened time to mTBI.
Capillary effect on water table fluctuations in unconfined aquifers
- Authors: Kong, Jun , Shen, Cheng-Ji , Xin, Pei , Song, Zhiyao , Li, Ling , Barry, David , Jeng, Dong-Shen , Stagnitti, Frank , Lockington, David , Parlange, Jean Yves
- Date: 2013
- Type: Text , Journal article
- Relation: Water Resources Research Vol. 49, no. 5 (2013), p. 3064-3069
- Full Text:
- Reviewed:
- Description: Parlange and Brutsaert (1987) derived a modified Boussinesq equation to account for the capillary effect on water table dynamics in unconfined aquifers. Barry et al. (1996) solved this equation subject to a periodic boundary condition. Their solution shows significant influence of capillarity on water table fluctuations, which evolve to finite-amplitude standing waves at the high frequency limit. Here we propose a new governing equation for the water table, which considers both horizontal and vertical flows in an unsaturated zone of finite thickness. An approximate analytical solution for periodic water table fluctuations based on the new equation was derived. In agreement with previous results, the analytical solution shows that the unsaturated zone's storage capacity permits water table fluctuations to propagate more readily than predicted by the Boussinesq equation. Furthermore, the new solution reveals a capping effect of the unsaturated zone on both the amplitude and phase of the water table fluctuations as well as the water table overheight. Due to the finite thickness of the unsaturated zone, the capillary effect on water table fluctuations is modified mainly with reduced amplitude damping and phase shift. ©2013. American Geophysical Union. All Rights Reserved.
- Description: 2003011129
Porous media pressure distribution in centrifugal fields
- Authors: Hogarth, William , Stagnitti, Frank , Barry, David , Lockington, David , Li, Ling , Parlange, Jean Yves
- Date: 2013
- Type: Text , Journal article
- Relation: Water Resources Research Vol. 49, no. 10 (October 2013 2013), p. 7133-7138
- Full Text: false
- Reviewed:
- Description: The simplest use of centrifuges to measure soil properties relies on steady state conditions. Analytical solutions, especially if they are simple, make interpretation of data more direct and transparent. Previous approximations are simplified and have a greatly improved accuracy. Using previous examples as a test, the error on pressure is always less than 1%, compared to about 10% with previous approximations.
- Description: C1