Cervical human spine loads during traumatomechanical investigations

The last decade's improvements in automotive safety resulted into a significant decrease of fatal injuries. However, due to the use of belts and airbags it can be observed that cervical spine injuries, non-severe and severe, have become more important. It seems that inertial loading of the neck by the head is an important loading mechanism causing these injuries. Until now local deformations and load paths in the cervical spine can not be determined accurately from cadaver experiments due to the lack of adequate measuring techniques. At this moment the loads at the occipital condyles can be estimated by analyzing high-speed film and the linear and angular accelerations of the head. These loads show a correlation with (local) cervical spine injuries in car crashes. The head-neck response, the neck loads and the sustained injuries obtained from human cadaver experiments in the frontal, lateral and rear-end collisions were investigated to increase the knowledge of the traumatomechanics of the cervical spine. The severity of these experiments, e.g., sled deceleration, varies from 11 to 15 g for frontal, and 7 g for rear-end collisions; for lateral impacts, the shoulder was accelerated with 100 to 130 g through the intruded side wall of the car. It was observed, that rotational accelerations of 1000 rad/sec²do not lead to recognizable injuries during postmortem loadings, while rotational accelerations of 2000 - 3000 rad/sec²or bending moments of 80 - 100 Nm can lead to injuries of ligaments, intervertebral discs and compression fractures of vertebral bodies. Shear forces in frontal collisions of 1000 - 1500 N at the level of the occipital condyles cause strength of the joints in this region. The resultant acceleration at the head center of gravity varies from 20 to 45 g

Automation and Experience of Controlled Crystal Dehydration Results from the European Synchrotron HC1 Collaboration

Controlled dehydration of macromolecular crystals can lead to significant improvements in crystalline order, which often manifests itself in higher diffraction quality. Devices that can accurately control the humidity surrounding crystals on a beamline have led to this technique being increasingly adopted as experiments become easier and more reproducible. However, these experiments are often carried out by trial and error, and in order to facilitate and streamline them four European synchrotrons have established a collaboration around the HC1b dehydration device. The MAX IV Laboratory, Diamond Light Source, BESSY II, and the EMBL Grenoble Outstation ESRF have pooled information gathered from user experiments, and on the use of the device, to propose a set of guidelines for these experiments. Here, we present the status and automation of the installations, advice on how best to perform experiments using the device, and an analysis of successful experiments that begins to show some trends in the type of protocols required by some systems. The dehydration methods shown are applicable to any device that allows control of the relative humidity of the air surrounding a macromolecular crysta