An investigation into the effect on skin surface temperature of three cryotherapy modalities

OBJECTIVE: To investigate the comparative cooling effect at the knee, of Crushed Ice and two commonly used commercial cryotherapy modalities, following a clinically relevant application of 20 minutes. DESIGN: Within subjects, randomised cross over design. SETTING: University Laboratory PARTICIPANTS: Eleven healthy male participants MAIN OUTCOME Measures: Skin temperature over the anterior knee measured by thermal imaging camera. RESULTS: Mean absolute baseline skin surface temperature (Tsk) was 28.4ºC (±1.2 ºC). The greatest reduction in Tsk was produced by Crushed Ice D14.6 ºC (±3.7 ºC) resulting in an absolute Tsk of 13.8 ºC; followed by Ice Man D12.3 ºC (±2.4 ºC) resulting in an absolute Tsk of 16.1ºC and then Arctic Flow D4.9 ºC (±1.3 ºC) resulting in an absolute Tsk of 23.5ºC. One-way ANOVA revealed significant differences (p<.05) between modalities for change in Tsk. CONCLUSIONS: Crushed Ice and Ice Man produced very similar results following a 20 minute application to healthy adult male knees, however only Crushed Ice resulted in a skin temperature in the desired 10-15°C therapeutic range, results for Ice Man were just above this range. The resultant skin temperature following a similar application of Arctic Flow was well above the therapeutic range

Design and implementation of a sector-based airspace model for the MIT Extensible Air Network Simulation

Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2006.Includes bibliographical references (p. 83-84).The MIT Extensible Air Network Simulation (MEANS) is a tool that has been designed to assist airline schedulers and air traffic managers in predicting flight delays for given air traffic scenarios. One aspect of the simulation, the determination of flight times, has received criticism from the MEANS users as being too simplistic for their needs. Currently, MEANS predicts flight times based on a historical distribution of observed flight times between city pairs. This system ignores the effects of flight level winds and airspace congestion, two major determiners of flight time. The replacement flight time model presented divides the airspace into discrete sectors based on existing divisions in air traffic control. Each sector has its own wind conditions and capacity limitations which affect passing flights. Results show that, after some calibration, the new flight time model produces accurate flight times when the airspace is divided into ARTCC domains and does not introduce additional errors into other parts of the simulation. Additionally, test scenarios show that the new system is capable of modeling airspace capacity events, such as a radar failure. Comparative results reveal that the old, distribution model produces surprisingly accurate flight times for typical wind conditions and airspace utilization.by Colin J. Whittaker.M.Eng

The impact of targeting all elderly persons in England and Wales for yearly influenza vaccination: excess mortality due to pneumonia or influenza and time trend study.

OBJECTIVE: To investigate the impact on mortality due to pneumonia or influenza of the change from risk-based to age group-based targeting of the elderly for yearly influenza vaccination in England and Wales. DESIGN: Excess mortality estimated using time series of deaths registered to pneumonia or influenza, accounting for seasonality, trend and artefacts. Non-excess mortality plotted as proxy for long-term trend in mortality. SETTING: England and Wales. PARTICIPANTS: Persons aged 65-74 and 75+ years whose deaths were registered to underlying pneumonia or influenza between 1975/1976 and 2004/2005. OUTCOME MEASURES: Multiplicative effect on average excess pneumonia and influenza deaths each winter in the 4-6 winters since age group-based targeting of vaccination was introduced (in persons aged 75+ years from 1998/1999; in persons aged 65+ years from 2000/2001), estimated using multivariable regression adjusted for temperature, antigenic drift and vaccine mismatch, and stratified by dominant circulating influenza subtype. Trend in baseline weekly pneumonia and influenza death rates. RESULTS: There is a suggestion of lower average excess mortality in the six winters after age group-based targeting began compared to before, but the CI for the 65-74 years age group includes no difference. Trend in baseline pneumonia and influenza mortality shows an apparent downward turning point around 2000 for the 65-74 years age group and from the mid-1990s in the 75+ years age group. CONCLUSIONS: There is weakly supportive evidence that the marked increases in vaccine coverage accompanying the switch from risk-based to age group-based targeting of the elderly for yearly influenza vaccination in England and Wales were associated with lower levels of pneumonia and influenza mortality in older people in the first 6 years after age group-based targeting began. The possible impact of these policy changes is observed as weak evidence for lower average excess mortality as well as a turning point in baseline mortality coincident with the changes

Mixing Dynamics at the Large Confluence Between the Yangtze River and Poyang Lake

Mixing processes downstream of river confluences impacts the ecology and the related environmental management of river networks. A clear understanding of such processes is challenging, especially for confluences having width-to-depth ratios larger than 100, due to the limited available field data. In this study, four field surveys based on hydro-acoustic and conductivity measurements were conducted near the confluence between the Yangtze River and the Poyang Lake, which are the largest river and freshwater lake in China, respectively. It was found that mixing dynamics at the confluence were controlled by a complex interaction among the momentum flux ratio, secondary flow and the lock-exchange flow associated to the density contrast between the two tributaries. Slow mixing was observed during high-flow conditions that generated dual counter-rotating secondary cells, with the downwelling flow acting as a barrier in the post-confluence channel. In contrast, more rapid mixing was observed during low-flow conditions when only a single channel-scale secondary flow was identified. The mixing processes were also affected by the lock-exchange flow associated to the density difference between the two confluent flows. Such lock-exchange enhanced mixing when the Yangtze River waters had higher temperature, that is, lower density than that of the Poyang Lake. In low flow condition, the penetration of the much larger momentum flux of Yangtze River created a “two-layers” structure with the contribution of the density difference, which further enhanced the curvature-induced helicity. The findings from the present study improve our current understanding of mixing dynamics in large river confluences