Sibship effects on dispersal behaviour in a pre-industrial human population.

Understanding dispersal behaviour and its determinants is critical for studies on life-history maximizing strategies. Although many studies have investigated the causes of dispersal, few have focused on the importance of sibship, despite that sibling interactions are predicted to lead to intrafamilial differences in dispersal patterns. Using a large demographic data set from pre-industrial Finland (n = 9000), we tested whether the sex-specific probability of dispersal depended on the presence of same-sex or opposite-sex elder siblings who can both compete and cooperate in the family. Overall, following our predictions, the presence of same-sex elder siblings increased the probability of dispersal from natal population for both sexes, whereas the number of opposite-sex siblings had less influence. Among males, dispersal was strongly linked to access to land resources. Female dispersal was mainly associated with competition over availability of mates but likely mediated by competition over access to wealthy mates rather mate availability per se. Besides ecological constraints, sibling interactions are strongly linked with dispersal decisions and need to be better considered in the studies on the evolution of family dynamics and fitness maximizing strategies in humans and other species.

[Evaluation of the postoperative clinical results of repositioning isolated zygomatic fractures]. / Beurteilung des postoperativen klinischen Repositionsergebnisses isolierter Jochbeinfrakturen.

This retrospective study included 148 patients who were evaluated for postoperative long-term results after osteosynthesis of isolated zygoma fractures. The influence of open reposition of the zygomaticoalveolar crest to middle face symmetry was evaluated quantitatively with a zygometer. In dependence on operative management patients were divided into two groups: In group I zygomaticofrontal suture (1-point-fixation) and infra-orbital rim were exposed (2-point-fixation), followed by osteosynthesis. In group II additional exposure of zygomaticoalveolar crest was performed and if required osteosynthesis was performed (3-point-fixation). For osteosynthetic reconstruction of isolated zygoma fractures the only 2-point-fixation is usually enough to achieve lateral middle face symmetry. In all cases zygomaticofrontal suture and alternatively infra-orbital rim or respectively zygomaticoalveolar crest should be supplied osteosynthetically. A further 3-point-fixation is indicated only in exceptional cases--for example comminuted fractures of lateral middle face columns. For an exact anatomical reposition of zygoma fractures the exposition and possible osteosynthesis of zygomaticoalveolar crest is recommended.

[Influence of different mixing fluids on mechanical and micromorphological in vitro qualities of hydroxyapatite cement]. / Einfluss unterschiedlicher Anrührflüssigkeiten auf die mechanischen und mikromorphologischen In-vitro-Eigenschaften von Hydroxylapatitzement.

AIM: In reconstructive craniofacial surgery a new synthetic hydroxyapatite cement has been used in the last few years. Tetra- and dicalcium phosphates react with either slow setting aqua bidest. or with faster setting sodium monophosphate solution to hydroxyapatite. The aim of this study was to investigate the two mixing fluids of hydroxyapatite for resulting micromorphology, pressure strength, and interactions with fibroblasts. MATERIAL AND METHODS: Pressure strength tests of hydroxyapatite cement test samples (n=80) were performed after a setting time of 3 and 24 h. The micromorphology of surfaces of the resulting particles was assessed under an electron microscope. In cell cultures L-929 and HEp2 cells were incubated with test samples and cell growth was assessed by light and electron microscopy. RESULTS: The test samples mixed with sodium monophosphate solution showed statistically significantly higher values of pressure strength. The resulting pressure strength depended on respective mixing fluids, setting time, and pressure of application. In general, test samples mixed with sodium monophosphate solution showed a more load-stable, homogeneous anorganic matrix whereas test samples mixed with aqua bidest. had a porous microarchitecture which was more fragile. In cell culture the porous structure showed disintegration in cell culture medium. CONCLUSION: To what extent the two mixing liquids of hydroxyapatite cement influence the resorption and bony substitution has to be shown in further studies.