Let $G$ be a finite group. The graph $D(G)$ is a divisibility graph of $G$. Its vertex set is the non-central conjugacy class sizes of $G$ and there is an edge between vertices $a$ and $b$ if and only if $a|b$ or $b|a$. In this paper, we investigate the structure of the divisibility graph $D(G)$ for a non-solvable group with $sigma^{ast}(G)=2$, a finite simple group $G$ that satisfies the one-p...

Thinking about the future of the RBO automatically leads to reflection on the future of our specialty, since it is certain that the RBO will be responsible for publicizing this future. Taking a light but critical tone, I reflected on the progress of orthopedics over the last few years, by asking: In what way have we evolved? Is there much to be done? Recently, we commemorated the hundredth anni...

Philosophers are very fond of making non-factualist claims—claims to the effect that there is no fact of the matter as to whether something is the case. But can these claims be coherently stated in the context of classical logic? Some care is needed here, we argue, otherwise one ends up denying a tautology or embracing a contradiction. In the end, we think there are only two strategies availabl...

Borrelia burgdorferi can very quickly move from the site of a tick bite into the circulatory system, where it can circulate throughout the body. This unique bacterium has a distinct and insidious method for passing through the capillary walls of blood vessels and nestling its way deep inside many organs and tissues of the human body. In animal models, the Lyme spirochete within mere hours of a ...