| The basic characteristics of extreme events are their infrequence and potential damages to the human nature system. |
| Irradiated human tissues are difficult to obtain due to the relative infrequence of surgical intervention after irradiation and the absence of adequate annotation of tissues obtained from large tissue banks. |
| That is probably attributable both to its relative infrequence and seeming lack of rational purpose. |
| Due to the relative infrequence of symptomatic thromboembolic events while using pharmacological agents as prophylaxis, an unmatched case-control study design was employed. |
