Ancestral reproductive bias in continuous-time branching trees under various sampling schemes.

Cheek and Johnston (JMB 86:70, 2023) consider a continuous-time Bienaymé-Galton-Watson tree conditioned on being alive at time T. They study the reproduction events along the ancestral lineage of an individual randomly sampled from all those alive at time T. We give a short proof of an extension of their main results (Cheek and Johnston in JMB 86:70, 2023, Theorems 2.

Muller's ratchet in a near-critical regime: Tournament versus fitness proportional selection.

Muller's ratchet, in its prototype version, models a haploid, asexual population whose size N is constant over the generations. Slightly deleterious mutations are acquired along the lineages at a constant rate, and individuals carrying less mutations have a selective advantage. The classical variant considers fitness proportional selection, but other fitness schemes are conceivable as well.

Is there any sustained effect of the coronavirus disease 2019 pandemic? - A controlled trial comparing pre- and post-pandemic oral radiology courses.

Purpose/objectives: Due to the coronavirus disease 2019 (COVID-19) pandemic, undergraduate education shifted towards online-only formats from April 2020 until July 2021. Previous research indicated a negative effect on students' competence development, and it remains unclear whether blended learning concepts could provide compensation. Therefore, the present study aimed to compare pre- to post-pandemic students' performance in standardized baseline (BL) and final exams (FE), as well as the associated knowledge gain (KG) in three consecutive undergraduate blended learning-based oral radiology courses (C1-3).