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OBJECTIVES The objective of this study to examine the reliability and repeatability of the headband sensor in comparison with the gold standard 3 linear and 3 angular rate sensors placed at the center of gravity of the Hybrid III dummy head during drop tests. METHODS A SIM-G headband sensor was attached to a Hybrid III dummy head and neck which was equipped with a triaxial accelerometer and 3 angular rate sensors. Linear acceleration and angular rate was sampled at 10,000 Hz while the SIM-G headband was sampled at 1000 Hz and 800 Hz respectively. A drop test was developed to test between 20 to 140 g and consisted of a total of 400 impacts in four locations, left occipital, right occipital, frontal and rear impacts with 100 impacts per location. Multiple tests were performed at the same height to verify the reliability of the devices. SIM-G data and the reference sensors were compared for validity. RESULTS The reliability measured by Cronbach's alpha showed very high repeatability for the SIM-G (α = 0.97-0.99). However, the validity measurement, Pearson's Correlation coefficient (r), showed a weak to very strong relationship (r=0.2-0.9). CONCLUSIONS While using the SIM-G sensor to help monitor head impact, the weak to strong validity of the SIM-G sensor must be carefully considered by the clinicians or researchers as a serious limitation.

Objective: To optimize the method of isolating a small amount of metagenomic DNA efficiently from bronchoalveolar lavage fluids (BALF) of patients with stable chronic obstructive pulmonary diseases (COPD) , which will facilitate subsequent PCR and DNA sequencing., Methods: BALF (5mL) of stable COPD patients was spun down to collect the cells. To extract genomic DNA from Gram-positive bacteria more efficiently, QIAGEN's DNA extraction protocol was optimized as follows: Added Buffer ATL to the pellets and used bead tubes and tissue homogenizers to break cell walls; then added proteinase K and incubated; after adding Buffer AL and ethanol, pipetted the mixture into a DNeasy spin column then centrifuged; washed the column with Buffer AW1 and Buffer AW2, finally added 50 microL Buffer AE to elute DNA. After measuring the total DNA concentration, the bacterial 16S rDNA was amplified by PCR and amplicon libraries were created for further determination., Results: The DNA content of BALF with optimized protocols was 467.5 (135.0-1697.5) ng, which was significantly higher than those extracted with phenol-chloroform 95.0 (0-612.5) ng. After optimizing, more 16S rDNA PCR production can be obtained for future analysis (P = 0.002)., Conclusion: The optimized DNA extraction methods combining DNA isolation kits with bead-beating were more efficient in isolating tiny metagenomic DNA from BALF.