SummaryBackgroundArm wrestling has recently become one of the most popular sports among young people, mainly due to its simplicity and spectacularity. Yet, unfortunately it is also injury prone. The aim of the study was to perform a biomechanical analysis of the forces which act during arm wrestling, as well as to explain the mechanism of the occurrence of humeral fractures of a similar topology as observed on X-rays.Material/MethodsDuring the period 2001 to 2008 nine cases of humeral fractures resulting from arm wrestling were consulted and treated at the Clinic. The assessment of the limb condition included an interview and the examination of the fractured extremity. All the patients underwent surgical treatment, using the method of open reduction and internal fixation. The virtual dynamic model of the upper limb was established on the basis of a series of computer tomography scans of the bone, and literature data. The biomechanical analysis was carried out using the Finite Elements Method (FEM).ResultsThere were five cases of the 12-B1 type in the AO Classification with butterfly fragments in five cases, and four of the 12-A1 type without the butterfly fragment. The maximum bone stress resulting from torsional loading which occurs during arm wrestling amounted to 60 MPa and was located 115 mm above the elbow on the medial - posterior side of the humeral.ConclusionsThe strength analysis carried out during arm wrestling revealed that the forces of the acting muscles significantly exert stresses within the distal third of the humeral.

OUTER SPACE AND PRIVATE COMPANIES The paper focuses on sectors, methods, and spheres of the space activity of private companies, to provide empirical analysis of space applications and implications for global security. Special emphasis has been given to private companies offering access to satellite imagery and satellite remote sensing, as well as companies entering outer space with new and prospective capabilities as space mining. The article explains the rising importance of geo-intelligence, space surveillance and telecommunication for global security and new kind of security challenges and vulnerabilities such as environmental problems in outer space or technological challenges to security. The author argues that profit-oriented companies play crucial role in new security environment in the US, efficiently changing the law and practice. Finally he points out that new and growing market for subcontractors in space applications raises questions on growing dependence on private resources in traditional sphere of state activity, namely security, in this case provided from and through the outer space.

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