Intersecting dilated convex polyhedra method for modeling complex particles in discrete element method.

This paper describes a new method for representing concave polyhedral particles in a discrete element method as unions of convex dilated polyhedra. This method offers an efficient way to simulate systems with a large number of (generally concave) polyhedral particles. The method also allows spheres, capsules, and dilated triangles to be combined with polyhedra using the same approach. The computational efficiency of the method is tested in two different simulation setups using different efficiency metrics for seven particle types: spheres, clusters of three spheres, clusters of four spheres, tetrahedra, cubes, unions of two octahedra (concave), and a model of a computer tomography scan of a lunar simulant GRC-3 particle. It is shown that the computational efficiency of the simulations degrades much slower than the increase in complexity of the particles in the system. The efficiency of the method is based on the time coherence of the system, and an efficient and robust distance computation method between polyhedra as particles never intersect for dilated particles.

Trauma and couples: mechanisms in dyadic functioning.

Research traditionally has focused on the development of symptoms in those who experienced trauma directly but overlooked the impact of trauma on the families of victims. In recent years, researchers and clinicians have begun to examine how individual exposure to traumatic events affects the spouses/partners, children, and professional helpers of trauma survivors. The current study reports data from a larger mixed-methodology study that includes qualitative interview data from 17 individuals, coded to identify the mechanisms that may affect the couple's interpersonal functioning when there is a history of trauma exposure in one or both partners. The following primary themes were identified: role in the relationship, boundary issues, intimacy problems, triggers, and coping mechanisms. Areas for future research and clinical implications also are identified.

The effects of trauma on intimate relationships: a qualitative study with clinical couples.

Research has traditionally focused on the development of symptoms in those who experienced trauma directly but has overlooked the impact of trauma on victims' families. In recent years, researchers and clinicians have begun to examine how individual exposure to traumatic events affects the spouses or partners, children, and professional helpers of trauma survivors. The current study examines qualitative interview data from 17 individuals, analyzed using a retroductive methodology to identify how intimate relationships are affected when there is a history of trauma exposure. The following primary themes were identified: increased communication, decreased communication, increased cohesion/connection, decreased cohesion/connection, increased understanding, decreased understanding, sexual intimacy problems, symptoms of relationship distress, support from partner, and relationship resources. Areas for future research and clinical implications are identified.