Aspects of three-dimensional constrained Delaunay meshing

Presented in this paper are the theoretical aspects of node addition to a non-convex, multiboundary mesh of tetrahedral elements as used in finite element modelling. The method used is derived from Watson¹ and Shenton and Cendes² and is extended to deal with node addition on inter-material boundaries. Several situations are identified that result in an illegal insertion polyhedron (IP), these could be caused by the ‘constrained’ nature of the mesh, adjacent objects with different material properties, or degenerate node configurations. A new Delaunay algorithm is described that checks for illegal cases of the IP and then corrects them, this checking relies on the consistent ordering of the element nodes. It is shown that a particular type of illegal IP can easily be identified and corrected using this technique. The Delaunay algorithm is then applied to automatic mesh generation, and modification to the basic Delaunay algorithm is described so that previously meshed edges and faces of the current object being meshed are not deleted during the addition of subsequent nodes. This ‘protection’ method only becomes viable by recognizing the node ordering sense of the IP faces.     

Dual immunodetection and hybridisation in situ of opsin mRNA and rhodopsin protein in retinal sections

We describe a simple method for combining in situ hybridisation and immunohistochemistry on the same retinal section. The technique was developed using a radiolabelled cDNA probe for opsin and an antibody (ROS1F4) against rhodopsin. This method retains the antigenic sites if immunocytochemistry is performed prior to in situ hybridisation. Opsin mRNA was found in the photoreceptor inner segment with rhodopsin immunolocalised to the photoreceptor outer segments. The technique should be applicable to numerous situations including analysis of the sequence of events in the expression and synthesis of the various opsins during retinal development and degeneration.     

Barriers to Increased Engineering Graduate Enrollments: Counterforces and Their Implementation

This paper highlights the role of the faculty member in recruiting students currently enrolled in B.S. programs in engineering and the sciences into full-time pursuit of a graduate-level engineering degree. The faculty member is demonstrated to be in a unique position to influence such students, providing strong counterforces to a confluence of attitudes and pressures experienced during the B.S. experience which effectively create a barrier to full-time engineering graduate study. We analyze this barrier via the method of force field analysis, and demonstrate that effective recruitment into full-time graduate study must be based on a four-fold strategy of education, expectations, improved B.S. experience and better control of the B.S. environment. Approaches to implement these strategies are discussed.     

The isolated air perfused rat heart

A simple method has been developed for continuous monitoring of metabolic activity of an isolated, perfused rat heart by O2/CO2 respirometer. Since respirometer provides vital data on oxygen consumption and carbon dioxide production of a preserved organ on a continuous basis over a long period of time, it will be possible to use this method to monitor viability of not only isolated heart but also any given donor organ under preservation.     

Esterified estrogens with and without methyltestosterone decrease arterial LDL metabolism in cynomolgus monkeys

OBJECTIVES: To assess retinal complications and to identify risk factors for retinal complications following aqueous shunt procedures. MATERIALS AND METHODS: Records of 38 consecutive aqueous shunt procedures that were performed on 36 patients at the Eye Institute of the Medical College of Wisconsin, Milwaukee, from June 1993 to March 1995 (minimum follow-up, 6 months) were reviewed. The mean +/- SD follow-up was 11.4 +/- 5.2 months (median, 10.5 months). RESULTS: Twelve patients (32%) had the following retinal complications: 4 serous choroidal effusions (10%) that required drainage, 3 suprachoroidal hemorrhages (8%), 2 vitreous hemorrhages (5%), 1 rhegmatogenous retinal detachment (3%), 1 endophthalmitis (3%), and 1 scleral buckling extrusion (3%). Surgical procedures for retinal complications were required in 8 (67%) of these 12 patients. Visual acuity decreased 2 lines or more in 9 (75%) of these 12 patients. The median onset of a postoperative retinal complication was 12.5 days, with 10 patients (83%) experiencing complications within 35 days. Serous choroidal effusions developed in 10 other patients (26%), and these effusions resolved spontaneously. Visual acuity decreased 2 lines or more in 2 (20%) of these additional 10 patients. Patients who experienced serious retinal complications were significantly older, had a higher rate of hypertension, and postoperative ocular hypotony. Serious retinal complications were distributed evenly among patients with Krupin valves with discs and Molteno and Baerveldt devices. Experience with the Ahmed glaucoma valve implant was limited. CONCLUSION: Aqueous shunt procedures may be associated with significant retinal complications and subsequent visual loss.     

A new protocol for training severely impaired patients in the usage of memory journals

Although memory disorders are frequently seen in survivors of brain injuries, remediation of patients with severe memory disorders is still relatively neglected in clinical practice due to pessimism by clinicians regarding the efficacy of such remediation. With respect to memory journal training, a further reason for this neglect is likely the lack of readily accessible protocols that therapists can use to work with these patients. The purpose of the present paper is to describe a new memory journal training protocol that was developed to teach brain injury survivors how to compensate for severe memory impairments by using three strengths of most brain injury survivors: immediate attention, procedural memory, and old learning. A training protocol is described that involves baseline testing and a needs assessment, five levels of training exercises, and discharge probe testing. It is concluded that patients with severely impaired memory abilities can learn the present system when care is taken to individualize journals, conduct proper needs assessments, and provide structured training exercises geared to the strengths of memory impaired persons.     

Weak interactions and lessons from crystallization

Ideas derived from the study of the process of crystallization may provide insights into molecular recognition in biological systems. Both processes exploit the cooperativity which arises from the formation of a large array of weak interactions.