background: motorcycle accidents and sport accidents lead yearly to many head injuries like head fractures and concussion. so finding the most proper helmet for reducing the injuries to head can be very helpful for head protection in such cases. methods: after 3d modeling of the helmet and head and meshing the model, a compressive impacting load of 1.31mpa was exerted on head and the model was ...

This article utilizes the average stress method to obtain the stress intensity factor of rotating solid and hollow disks/cylinders containing a radial crack‎. ‎It is assumed that the cracks are located radially at center‎, ‎internal or external radius of the geometry‎. ‎Results are shown for both of the plane stress and plane strain assumptions and are validated against the known data introduce...

Stress fracture of the carpal scaphoid is very rare. We present stress fracture of the scaphoid in an adolescent gymnast who was treated with internal fixation. Key pointsThere is a risk of stress fracture of the scaphoid in gymnast.Internal fixation with a screw is one of the good options for stress fracture of the scaphoid.

Since crystals are made of periodic structures in space, determining their three independent period vectors in theory (starting from any values) is a basic physics problem. For the general situation where crystals are under constant external stress, we derived dynamical equations of the period vectors in the framework of Newtonian dynamics, for pair potentials recently (doi:/10.1139/cjp-2014-05...

aim and background: perfectionism is known as a potential maladaptive personality trait with significant psychological consequences. the purpose of this study was to investigate the relations between stress and positive and negative perfectionism in normal subjects. methods and materials: using convenience sampling method, 162 adults who aged 18-50 years old and did not have a history of any sp...