Attitudes and behaviors regarding sun exposure in Japan compared to Europe and North America.

The objective of our study was to assess the attitudes and behaviors in Japan regarding sun exposure and compare them to those in Europe and North America. The study population was a representative sample of individuals aged >18 years from Ipsos panels in Japan (N = 1000), North America (N = 1000), and Europe (N = 6000) using the quota method. Questionnaires covered habits, practices, and perceptions regarding sun exposure. Results revealed that the majority of people (80.1%) believed that the sun gives them energy, and 61.1% considered that being tanned made them look healthier. However, there was a significant difference between men and women regarding the appeal of tanned skin, with 54.95% of men versus 34.67% (p < 0.001) of women seeing a tan as an aesthetic asset. People aged <40 years were less likely to find a tan attractive (30.3%) compared to those aged ≥40 years (48.9%) (p < 0.001). Of those questioned, 45.70% of used sunscreen with a much higher use among women (70.10%) than men (18.74%) (p < 0.001). Almost 54% of people said they stayed in the shade to protect themselves from the sun with this behavior being more prevalent among women (67.05%) and fair-skinned individuals (56.13%). Fear of the risks of sun exposure was more common among women, with 84.8% fearing premature skin aging, compared to 71.8% of men (p < 0.001). In Japan, 44.30% of those questioned said tanned skin was attractive (p < 0.001); for Europeans and North Americans the proportions were 81.1% and 77.6%, respectively. Only a quarter (25.80%) thought it essential to return from vacation with a tan. On the other hand, Europeans showed a strong recognition of the energy the sun brings (83.18%), and widely believed that tanned skin is attractive (82.32%) and healthy (73.15%). In North America, attitudes were similar to those in Europe regarding the attractiveness of tanned skin (77.65%) and the importance of returning tanned from vacation (48.15%). Compared to Europeans and North Americans, the Japanese seemed to be more cautious about sun-induced hazards and considered lighter skin to be more attractive.

Study of the deformations of the isolated mandible under static constraints by simulation on a physicomathematical model.

The authors have studied the deformations of a mandible isolated from its muscular environment and submitted to statical constraints, with the help of a "modified model" and the finite elements method: the general deformation of the mandible and its modifications according to the direction of the application of the pressure, the rotation phenomenon or "torsion" in cross sections (identified by computer) of the mandible, the respective deformations of the internal and external corticals have successively been calculated. Particular mechanical phenomenons corresponding to the areas where the anatomo-clinical forms of the mandibular fractures take place have clearly been shown. The authors draw the conclusion that the mandible behaves mechanically in a similar way to a tridimensional composite.

Study of the mandible under static constraints by holographic interferometry. New biomechanical deductions.

In order to try to determine the nature of the mechanical structure of the mandible, the authors have compared, with the help of holographic interferometry, the behavior of the fresh mandible of a corpse, of a representative iron angle, and of a block of carbon-carbon under static constraint. There are no similarities between the behavior of the human mandible and that of a polycrystalline steel. On the contrary, the behavior of the mandible and of the carbon-carbon block are very similar. It would be hasty to state that bones are a heterogeneous composite. We can only prove, in a first approach, that they behave similarly under identical experimental conditions. The authors also demonstrated that the mandible presents a "mechanical hysteresis" phenomenon. This means that, when subjected to a small strain, its shape changes, but this change tends to neutralize itself in part in the course of time.