CHEST I 103 I 6 I JUNE, 1993 1887 Pulmonary actinomycosis usually occurs as a result of the aspiration of oropharyngeal material in the setting of poor dental hygiene or oral trauma. When pathogenic, it is invasive, often mimicking a malignancy in presentation and macroscopic appearance. Endobronchial disease due to this pathogen rarely is reported. Ariel et al recently described five patients ...

A sign pattern is a matrix with entries in {+, −, 0}. A full sign pattern has no zero entries. The refined inertia of a matrix pattern is defined and techniques are developed for constructing potentially nilpotent full sign patterns. Such patterns are spectrally arbitrary. These techniques can also be used to construct potentially nilpotent sign patterns that are not full, as well as potentiall...

Many graphics applications today have to cope with large amounts of data. A popular approach to reduce the amount of geometry to be rendered is to precompute visibility in order to render only objects that can be seen from the given viewpoint. This paper presents one technique to achieve this, potentially visible sets (PVS). These sets are used to avoid rendering hidden objects, especially geom...

The potentially preventable readmission (PPR) method uses administrative data to identify hospital readmissions that may indicate problems with quality of care. The PPR logic determines whether the reason for readmission is clinically related to a prior admission, and therefore potentially preventable. The likelihood of a PPR was found to be dependent on severity of illness, extremes of age, an...

We extend the notion of a potentially H-graphic sequence as follows. Let A and B be nonnegative integer sequences. The sequence pair S = (A,B) is said to be bigraphic if there is some bipartite graph G = (X ∪ Y, E) such that A and B are the degrees of the vertices in X and Y , respectively. If S is a bigraphic pair, let σ(S) denote the sum of the terms in A. Given a bigraphic pair S, and a fixe...