Size and albedo of Kuiper belt object 55636 from a stellar occultation.

The Kuiper belt is a collection of small bodies (Kuiper belt objects, KBOs) that lie beyond the orbit of Neptune and which are believed to have formed contemporaneously with the planets. Their small size and great distance make them difficult to study. KBO 55636 (2002 TX(300)) is a member of the water-ice-rich Haumea KBO collisional family. The Haumea family are among the most highly reflective objects in the Solar System. Dynamical calculations indicate that the collision that created KBO 55636 occurred at least 1 Gyr ago. Here we report observations of a multi-chord stellar occultation by KBO 55636, which occurred on 9 October 2009 ut. We find that it has a mean radius of 143 +/- 5 km (assuming a circular solution). Allowing for possible elliptical shapes, we find a geometric albedo of in the V photometric band, which establishes that KBO 55636 is smaller than previously thought and that, like its parent body, it is highly reflective. The dynamical age implies either that KBO 55636 has an active resurfacing mechanism, or that fresh water-ice in the outer Solar System can persist for gigayear timescales.

Optimizing the cut in Mohs' micrographic surgery in regard to skin sparing and microscopic view: is a round incision cut necessary?

Saucer incision is the common cut in Mohs' micrographic surgery. To date no proof as to the superiority of this cut over other patterns has been presented. In this work we examine the round pattern aspect of the saucer incision and answer two questions: does the round cut provide the best skin-sparing pattern? And, does it provide the best microscopic view? A two-dimensional geometric analysis is used to determine whether a round incision is optimal from the standpoint of skin sparing and microscopic view. Mohs' micrographic surgery views are used to back up the geometric hypothesis. The result is that the round incision pattern is skin-wasteful compared to an incision that follows the cancerous lesion. In the lesion presented here the two cuts have a ratio of 1.5 between the two excised skin areas, indicating a waste of healthy skin of 50%. It is also shown that specimens with a pointed edge provide better layer projection. The conclusion is that a tailored cut following the lesion pattern is the optimal Mohs' incision. Therefore in the first stage of Mohs' micrographic surgery the skin cut should replicate the lesion pattern instead of a round saucer cut. Though many Mohs' surgeons already implement this philosophy, in the literature the saucer incision recommended by Dr. Frederic Mohs' remains the norm.