Fracture Diodes: Directional Asymmetry of Fracture Toughness

Toughness describes the ability of a material to resist fracture or crack propagation. It is demonstrated here that fracture toughness of a material can be asymmetric, i.e., the resistance of a medium to a crack propagating from right to left can be significantly different from that to a crack propagating from left to right. Such asymmetry is unknown in natural materials, but we show that it can be built into artificial materials through the proper control of microstructure. This paves the way for control of crack paths and direction, where fracture-when unavoidable-can be guided through predesigned paths to minimize loss of critical components.

Stroke knowledge among stroke support group members

BACKGROUND AND PURPOSE

Community stroke education is needed to improve early stroke recognition and reduce delays in the referral of stroke patients. In some regions, stroke support groups are important promoters of regional stroke education. However, there are no data about the level of stroke knowledge among support group members that support this promotional role.

METHODS

We performed a cross-sectional questionnaire survey among 11 German stroke support groups. The questionnaire asked for stroke knowledge and sociodemographic and medical data. Stroke knowledge was excellent if a participant knew (1) at least 2 stroke symptoms (good symptom knowledge) and (2) at least 2 stroke risk factors (good risk factor knowledge), as well as knowing (3) that immediate hospital admission or an emergency call is necessary in case of stroke (good action knowledge).

RESULTS

A total of 133 members (96.2%) of 11 stroke support groups took part in the study. Mean age was 65.3 years (SD 11.2 years). Fifty-four percent of subjects were female, 72.8% were retired, and 69.8% were stroke patients. Of the participants, 80.3% had good symptom knowledge, 64.7% had good risk factor knowledge, and 79.7% had good action knowledge. Stroke knowledge was excellent in 44.0% of subjects. Logistic regression analysis showed that age <70 years and not having had a stroke were significant predictors for excellent stroke knowledge.

CONCLUSIONS

Overall, members of stroke support groups are well informed about all aspects of modern stroke care. Because of their knowledge and personal experience, support groups should be viewed as important partners in community stroke education.