Intercondylar eminence fracture treated by resorbable magnesium screws osteosynthesis: A case series.

Abstract Introduction Tibial spine avulsion fractures are mostly a paediatric injury which appropriate treatment is currently debated in literature. The choice between conservative and surgical treatment is based on the radiographic classification of Meyers-McKeever. The most diffused surgical techniques involve either internal fixation devices (screws) or bone tunnels fixation with resorbable sutures. Today, a third option is represented by resorbable magnesium screws which could combine the best features of the two classical systems. Objective of this study is to investigate the efficacy of these new devices in the surgical treatment of tibial spine avulsions. Materials and methods Since 2014 we have seen seven patients with tibial eminence fracture. Patients underwent clinical and radiological examination (MRI, CT scan) before surgery. Only 3 patients that presented with a grade III or IV lesion were treated surgically with internal fixation with magnesium resorbable screws. In post-operative follow-up, functional recovery was evaluated at 1, 2, 4, 6 and 12 months, clinically and by X-ray. Lysholm and IKDC scores were submitted at 1, 2, 6 and 12 months. MRI was repeated at 6 and 12 months. Results All three surgical patients showed progressive clinical and functional improvement during the follow-up period. The first case showed a quicker overall recovery rate, which might be due to the lower grade of the lesion. Radiographs and MRI evaluation showed regular healing of the injury. The devices appeared completely resorbed at the 6 months follow-up and replaced by newly formed bone at the 12 months follow-up. Conclusions The treatment of tibial spine avulsion fractures with arthroscopic reduction and internal fixation (ARIF) technique by magnesium resorbable screws seems to result in an excellent functional recovery without complications related to fixation devices, which were completely resorbed after 6 months and replaced by newly formed bone after 12 months. This new method could be considered as an alternative option to classic techniques by non resorbable fixation devices or bone tunnel fixation. Further studies are needed in order to evaluate the efficacy of these new devices in a wider group of patients

Terrestrial modification of the Ivuna meteorite and a reassessment of the chemical composition of the CI type specimen

The rare CI carbonaceous chondrites are the most aqueously altered and chemically primitive meteorites but due to their porous nature and high abundance of volatile elements are susceptible to terrestrial weathering. The Ivuna meteorite, type specimen for the CI chondrites, is the largest twentieth-century CI fall and probably the CI chondrite least affected by terrestrial alteration that is available for study. The main mass of Ivuna (BM2008 M1) has been stored in a nitrogen atmosphere at least since its arrival at the Natural History Museum (NHM), London, in 2008 (70 years after its fall) and could be considered the most pristine CI chondrite stone. We report the mineralogy, petrography and bulk elemental composition of BM2008 M1 and a second Ivuna stone (BM1996 M4) stored in air within wooden cabinets. We find that both Ivuna stones are breccias consisting of multiple rounded, phyllosilicate-rich clasts that formed through aqueous alteration followed by impact processing. A polished thin section of BM2008 M1 analysed immediately after preparation was found to contain sulphate-bearing veins that formed when primary sulphides reacted with oxygen and atmospheric water. A section of BM1996 M4 lacked veins but had sulphate grains on the surface that formed in ≤6 years, ∼3 times faster than previous reports for CI chondrite sections. Differences in the extent of terrestrial alteration recorded by BM2008 M1 and BM1996 M4 probably reflect variations in the post-recovery curation history of the stones prior to entering the NHM collection, and indicate that where possible pristine samples of hydrated carbonaceous should be kept out of the terrestrial environment in a stable atmosphere to avoid modification. The bulk elemental composition of the two Ivuna stones show some variability due to their heterogeneous nature but in general are similar to previous analyses of CI chondrites. We combine our elemental abundances with literature values to calculate a new average composition for the Ivuna meteorite, which we find is in good agreement with existing compilations of element compositions in the CI chondrites and the most recent solar photospheric abundances

Dem Andenken an Helmut Wyklicky (1921–2007) gewidmet. Veröffentlichungen der Kommission für Geschichte der Naturwissenschaften, Mathematik und Medizin|Ernst Fuchs und die Weltgeltung der Wiener Ophthalmologischen Schule um 1900 Veröffentlichungen der Kommission für Geschichte der Naturwissenschaften, Mathematik und Medizin 69|

IndiGolog is a programming language for autonomous agents that sense their environment and do planning as they operate. Instead of classical planning, it supports high-level program execution. The programmer provides a high-level nondeterministic program involving domain-specific actions and tests to perform the agent¿s tasks. The IndiGolog interpreter then reasons about the preconditions and effects of the actions in the program to find a legal terminating execution. To support this, the programmer provides a declarative specification of the domain (i.e., primitive actions, preconditions and effects, what is known about the initial state) in the situation calculus. The programmer can control the amount of nondeterminism in the program and how much of it is searched over. The language is rich and supports concurrent programming. Programs are executed online together with sensing the environment and monitoring for events, thus supporting the development of reactive agents. We discuss the language, its implementation, and applications that have been realized with it