Parting the Clouds

Parting Thoughts

It has been said that there is no stronger urge than the urge to edit someone else's writing. Upon my retirement from the National Institute of Environmental Health Sciences (NIEHS), and concurrently from my position as co-editor-in-chief of Environmental Health Perspectives, I find that perhaps the stronger urge is not to edit but rather to editorialize. Therefore, I would like to provide some...

Parting with illusions in evolutionary ethics

I offer a critical analysis of a view that has become a dominant aspect of recent thought on the relationship between evolution and morality, and propose an alternative. An ingredient in Michael Ruse’s ‘error theory’ (Ruse 1995) is that belief in moral (prescriptive, universal, and nonsubjective) guidelines arose in humans because such belief results in the performance of adaptive cooperative b...

Parting directions for mould and die design

On the basis, of the condition for demouldability, two levels of visibility, complete and partial visibility, are defined. The viewing directions from which a surface is completely visible can be represented as a convex region on the unit sphere called the visibility map of the surface. Algorithms are given for dividing a given object into pockets, for which visibility and demouldability can be...

Parting Words: Trauma, Silence, and Survival

Finding Undercut-Free Parting Directions for Polygons with Curved Edges

We consider the problem of whether a given geometry can be molded in a two-part, rigid, reusable mold with opposite removal directions. We describe an efficient algorithm for solving the opposite direction moldability problem for a 2D “polygon” bounded by edges that may be either straight or curved. We introduce a structure, the normal graph of the polygon, that represents the range of normals ...