A biomechanical comparison between human calvarial bone and a skull simulant considering the role of attached periosteum and dura mater.

PURPOSE: Current forensic analysis of blunt force trauma relies on the use of cadaveric or animal tissues, posing ethical and reproducibility concerns. Artificial substitutes may help overcome such issues. However, existing substitutes exhibit poor anatomic and mechanical biofidelity, especially in the choice of skull simulant material. Progress has been made in identifying materials that have similar mechanical properties to the human skull bone, with the potential to behave similarly in mechanical loading. AIMS: To compare the biomechanical properties of the human calvarial bone with an epoxy resin-based simulant material. Data collected was also used to analyse the effect of periosteal attachment on the mechanical properties of skull bone compared with that of the counterpart samples. METHODS: Fifty-six human skull bone specimens were prepared from two cadaveric heads. Half of these specimens were removed of periosteum and dura mater as the PR (periosteum removed) group, whereas periosteum was left attached in the PA (periosteum attached) group. Duplicates of the bone specimens were fabricated out of an epoxy resin and paired in corresponding PR and PA groups. The specimens were loaded under three-point bending tests until fracture with image-based deformation detection. RESULTS: Comparison of the epoxy resin and skull specimens yielded similarity for both the PR and PA groups, being closer to the PA group (bending modulus resin PR 2665 MPa vs. skull PR 1979 MPa, resin PA 3165 MPa vs. skull PA 3330 MPa; maximum force resin PR 574 N vs. skull PR 728 N, resin PA 580 N vs. skull PA 1034 N; strain at maximum force resin PR 2.7% vs. skull PR 5.1%, resin PA 2.3% vs. skull PA 3.5%, deflection at maximum force resin PR 0.5 mm vs. skull PR 0.8 mm, resin PA 0.5 mm vs. skull PA 1.0 mm). Bending strength was significantly lower in the resin groups (resin PR 43 MPa vs. skull PR 55 MPa, resin PA 44 MPa vs. skull PA 75 MPa). Moreover, the correlations of the mechanical data exhibited closer accordance of the PR group with the epoxy resin compared with the PA group with the epoxy resin. CONCLUSIONS: The load-deformation properties of the epoxy resin samples assessed in this study fell within a closer range to the skull specimens with PR  than with PA. Moreover, the values obtained for the resin fall within the reference range for skull tissues in the literature suggesting that the proposed epoxy resin may provide a usable artificial substitute for PA but does not totally represent the human skull in its complex anatomical structure.

An Investigation on the Correlation between the Mechanical Properties of Human Skull Bone, Its Geometry, Microarchitectural Properties, and Water Content.

With increasingly detailed imaging and mechanical analysis, modalities need arises to update methodology and assessment criteria for skull bone analysis to understand how bone microarchitecture and the presence of attached tissues may affect the response to mechanical load. The main aim was to analyze the effect of macroscopic and microstructural features, as well as periosteal attachment, on the mechanical properties of human skull bone. Fifty-six skull specimens from ethanol-phenoxyethanol-embalmed cadavers were prepared from two human cadavers. Assuming symmetry of the skull, all samples from one-half each were stripped of periosteum and dura mater, while the soft tissues were kept intact on the remaining samples on the contralateral side. The specimens were analyzed using microcomputed tomography to assess trabecular connectivity density, total surface area, and volume ratio. The specimens were loaded under three-point bend tests until fracture with optical co-registration. The bone fragments were then lyophilized to measure their water content. With increasingly detailed imaging and mechanical analysis modalities, there is a need to update methodology and assessment criteria for skull bone analysis to understand how the bone microarchitecture and the presence of attached tissues may affect the response to mechanical load. The mechanical properties were negatively correlated to bone thickness and water content. Conversely, most microarchitectural features did not influence either mechanical parameter. The correlation between mechanical response data and morphologic properties remains similar between the results of embalmed tissues presented here and fresh osseous tissue from literature data. The findings presented here add to the existing methodology to assess human skull for research purposes. The interaction between most microarchitectural features in ethanol-phenoxyethanol-embalmed embalmed skull samples and bending stress appear to be minute.

Prevention of problem gambling in Chinese adolescents: relevance of problem gambling assessment and positive youth development frameworks.

Although research findings show that adolescent gambling behavior is a growing problem, there are not many theory-driven prevention programs in the Chinese context. In this paper, two approaches of developing Chinese adolescent prevention program are described. In the first approach, it is argued that related programs should be developed with reference to the risk factors of problem gambling based on problem gambling assessment tools and frameworks. The modified Chinese G-MAP is used as an example to illustrate this approach. In the second approach, it is argued that programs incorporating positive youth development constructs would help adolescents develop positive qualities which would prevent them from developing problem gambling. The Project P.A.T.H.S. is given as an example. The issues related to the application of positive youth development constructs to adolescent problem gambling prevention are discussed.

Social network types and subjective well-being in Chinese older adults.

The study examined social network types in a sample of 1,005 older Chinese adults in Hong Kong and the networks' relations to subjective well-being. Given the nature of kinship in Chinese society, we broke down social support provision by closeness of blood ties (immediate kin, distant kin, and non-kin). Using K-means cluster analysis, we identified 5 network types: diverse, friend focused, restricted, family focused, and distant family. The latter was characterized by few immediate kin but mostly distant kin. Diverse and family-focused networks were most beneficial to well-being, whereas restricted networks were least. Distant family networks were associated with only marginally lower well-being than family-focused networks and were comparable to friend-focused networks. Results suggested the importance of the extended family in support provision for Chinese older adults, especially in the absence of immediate kin and friends. Implications of the present findings for other cultural groups are discussed.

MEMS micromirror characterization in space environments.

This paper describes MEMS micromirror characterization in space environments associated with our space applications in earth observation from the International Space Station and earth's orbit satellite. The performance of the micromirror was tested for shock and vibration, stiction, outgassing from depressurization and heating, and electrostatic charging effects. We demonstrated that there is no degradation of the micromirror performance after the space environment tests. A test bed instrument equipped with the micromirrors was delivered and tested in the ISS. The results demonstrate that the proposed micromirrors are suitable for optical space systems.

Differences between older Chinese men and women from Hong Kong in the impact of urinary incontinence on their lives.

This study reports the epidemiology of urinary incontinence (UI) and its impact on the social lives of older Chinese people in Hong Kong, a modern city in China. It also examines the relationship between sex and this impact, as well as the extent of UI in a convenience sample of 101 sufferers aged 60 or older. This study was cross-sectional and used face-to-face interviews with a structured questionnaire. A number of findings concur with studies conducted in Western countries. Prevalence of UI increased with adult age, and it affected women more than men. UI had a negative impact on 86.1% of the incontinent respondents. There were no significant differences between men and women in the duration of UI, the level of UI, or health status. Out of the nine impacts on social lives, only one showed a significant difference between older men and women: "restriction on opportunities to participate in social activities." Statistically, men tended to report more negative impacts than women. More than 80% of the respondents were affected by their UI. The impact of UI on social lives was basically the same for men and women, though men reported significantly more social impacts than did women. However, this study does not support the claim that the social life of those who reported more social impacts was worse than that of those who reported fewer.