Constructing Kinematic Confidence Regions With Double Quaternions.

A spatial displacement as an element of can be approximated by a 4D rotation, which is an element of . In this way, the problem of constructing confidence regions of uncertain spatial displacements may be studied as that of constructing confidence ellipsoids in . In this light, a double-quaternion formulation of kinematic confidence regions is presented that approximately preserve the geometry of .

On the Computation of the Average of Planar Displacements.

In this paper, we present four parametric representations of a planar displacements and studied the problem of how to compute the average displacement from a set of given planar displacements using these representations. It has been shown that the optimal average displacement is obtained by using planar quaternions and the concept of relative displacements. Examples are provided to show the comparisons of these methods.

The Dosimetric Outcome of a Rotational Planning Target Volume in Patients With Oropharyngeal Cancers.

An isotropic expanded Planning Target Volume (PTV) neglects patient's off-axis rotation. This study designs a rotational PTV that is used instead of the standard 3-mm Clinical Target Volume (CTV) expanded PTV in oropharyngeal cancers with the goal to reduce pharyngeal constrictor muscle (PCM) mean dose. 10 patients were retrospectively evaluated.

Cholesterol-like Condensing Effect of Perfluoroalkyl Substances on a Phospholipid Bilayer.

To understand the potential cytotoxicity of perfluoroalkyl substances (PFAS), we study their interactions with a model phospholipid bilayer membrane using molecular dynamics (MD) simulations. Four typical PFAS molecules are investigated, including perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), perfluorooctanesulfonic acid (PFOS), and perfluorohexane sulfonate (PFHxS). All of these PFAS molecules are found to spontaneously penetrate the lipid bilayer within a short simulation time (a few nanoseconds).

Aspirin-induced ultrastructural changes in human gastric mucosa: correlation with potential difference.

Aspirin breaks the gastric mucosal barrier. We studied the effect of aspirin on this barrier, correlating changes in potential difference and ultrastructure. Mean control potential difference for seven subjects was -48 +/- 1.