On Comments in Visual Languages

Visual languages based on node-link diagrams can be used to develop software and, like textual languages, offer the possibility to write explanatory comments. Which node a comment refers to is usually not made explicit, but is implicitly clear to readers through placement and content. While automatic layout algorithms can make working with diagrams more productive, they tend to destroy such implicit clues because they are not aware of them and thus do not preserve the relative placement of comments and the nodes they refer to. Implicit clues thus need to be inferred and made explicit to be taken into account by layout algorithms. This is what we call the comment attachment problem. In this paper, we improve upon a previous paper on the subject [9], introducing further heuristics that aim to describe relations between comments and nodes. Based on an analysis of comment placement in a set of example diagrams, we develop a general comment attachment framework and evaluate the quality of its inferred attachments

Single Application of Low-Dose, Hydroxyapatite-Bound BMP-2 or GDF-5 Induces Long-Term Bone Formation and Biomechanical Stabilization of a Bone Defect in a Senile Sheep Lumbar Osteopenia Model

Effects of hydroxyapatite (HA) particles with bone morphogenetic BMP-2 or GDF-5 were compared in sheep lumbar osteopenia; in vitro release in phosphate-buffered saline (PBS) or sheep serum was assessed by ELISA. Lumbar (L) vertebral bone defects (Ø 3.5 mm) were generated in aged, osteopenic female sheep ( n = 72; 9.00 ± 0.11 years; mean ± SEM). Treatment was: (a) HA particles (2.5 mg; L5); or (b) particles coated with BMP-2 (1 µg; 10 µg) or GDF-5 (5 µg; 50 µg; L4; all groups n = 6). Untouched vertebrae (L3) served as controls. Three and nine months post-therapy, bone formation was assessed by osteodensitometry, histomorphometry, and biomechanical testing. Cumulative 14-day BMP release was high in serum (76–100%), but max. 1.4% in PBS. In vivo induction of bone formation by HA particles with either growth factor was shown by: (i) significantly increased bone volume, trabecular and cortical thickness (overall increase HA + BMP vs. control close to the injection channel 71%, 110%, and 37%, respectively); (ii) partial significant effects for bone mineral density, bone formation, and compressive strength (increase 17%; 9 months; GDF-5). Treatment effects were not dose-dependent. Combined HA and BMPs (single low-dose) highly augment long-term bone formation and biomechanical stabilization in sheep lumbar osteopenia. Thus, carrier-bound BMP doses 20,000-fold to 1000-fold lower than previously applied appear suitable for spinal fusion/bone regeneration and improved treatment safety