Magnitude of head impact exposures in individual collegiate football players

The purpose of this study was to quantify the severity of head impacts sustained by individual collegiate football players and to investigate differences between impacts sustained during practice and game sessions, as well as by player position and impact location. Head impacts (N = 184,358) were analyzed for 254 collegiate players at three collegiate institutions. In practice, the 50th and 95th percentile values for individual players were 20.0 g and 49.5 g for peak linear acceleration, 1187 rad/s2 and 3147 rad/s2 for peak rotational acceleration, and 13.4 and 29.9 for HITsp, respectively. Only the 95th percentile HITsp increased significantly in games compared with practices (8.4%, p = .0002). Player position and impact location were the largest factors associated with differences in head impacts. Running backs consistently sustained the greatest impact magnitudes. Peak linear accelerations were greatest for impacts to the top of the helmet, whereas rotational accelerations were greatest for impacts to the front and back. The findings of this study provide essential data for future investigations that aim to establish the correlations between head impact exposure, acute brain injury, and long-term cognitive deficits.     

Alkaloids from Glycosmis cochinchinensis twigs

A phytochemical investigation of the twigs of Glycosmis cochinchinensis led to the isolation of two new alkaloids, glycosmisacridone (1) and glycosmisindole (2), together with eight known compounds (3–10). Their structures were elucidated by intensive analysis of their spectroscopic data. Compound 9 exhibited moderate antibacterial activity against methicillin-resistant Staphylococcus aureus SK1with an MIC value of 16 μg/mL.     

Ein neuer kapazitiv arbeitender Aktograph

Summary Capacitance sensing devices are useful for ecological and ethological studies (Zucker et al., 1968). If the location and activity of small animals (e.g. newts) is to be recorded, problems arise due to the very small changes in capacitance that must be detected reliably. By using a special bridge circuit (Fig. 2) an extremely sensitive detector can be constructed. With the output voltage and frequency of the RF-generator kept constant, the RF-current is determined only by the capacitance of the two sensors C₁ and C₂. This current is rectified by the transistors T₁ and T₂ and the difference is detected by a Schmitt trigger. Outside influences that affect both sensors in the same way will thus be eliminated, resulting in excellent long-time stability and sensitivity of the device.The sensors simply consist of copper foils, about 1 cm apart, glued onto an insulating, flat surface. A glass with the animal is placed on these sesors and no further connection is necessary. The change in capacitance is generated by the animals building a capacitance bridge over the space between the foils. By a suitable arrangement of foils and spaces (Fig. 3), any desired information can be obtained concerning activity, time of entering and leaving the hiding place, etc.Newts and salamanders need a damp atmosphere. It was found that a moist paper on the bottom of the container will increase the sensitivity if its degree of humidity be kept constant.