On the Qualitative Behavior of Impurity-Based Splitting Rules I: The Minima-Free Property

We show that all strictly convex n impurity measures lead to splits at boundary points, and furthermore show that certain rational splitting rules, notably the information gain ratio, also have this property. A slightly weaker result is shown to hold for impurity measures that are only convex n, such as Inaccuracy

Applications of Simple Markov Models to Computer Vision

In this report we advocate the use of computationally simple algorithms for computer vision, operating in parallel. The design of these algorithms is based on physical constraints present in the image and object spaces. In particular, we discuss the design, implementation, and performance of a Markov Random Field based algorithm for low level segmentation. In addition to having a simple and fast implementation, the algorithm is flexible enough to allow intensity information to be fused with motion and edge information from other sources

The influence of miniscrew insertion torque

Objective: The aim of this in vitro study was to evaluate the progressive development of surface microdamage produced following the insertion of orthodontic miniscrews (OMs) into 1.5 mm thick porcine tibia bone using maximum insertion torque values of 12 Ncm, 18 Ncm, and 24 Ncm.Methods: Aarhus OMs (diameter 1.5 mm; length 6 mm) were inserted into 1.5 mm porcine bone using a torque limiting hand screwdriver set at 12 Ncm, 18 Ncm, and 24 Ncm. A custom rig equipped with a compression load cell was used to record the compression force exerted during manual insertion. A sequential staining technique was used to identify microdamage viewed under laser confocal microscopy. Virtual slices were created and stitched together to form a compressed two-dimensional composition of the microdamage. Histomorphometric parameters, including total damage area, diffuse damage area, maximum crack length, maximum damage radius, and maximum diffuse damage radius, were measured. Kruskal-Wallis Tests and Wilcoxon Rank-Sum Tests were used to analyse the generated data.Results: All OMs inserted using 12 Ncm failed to insert completely, while partial insertion was observed for two OMs inserted at 18 Ncm. Complete insertion was achieved for all OMs inserted at 24 Ncm. Histomorphometrically, OMs inserted using 24 Ncm produced a significantly larger diffuse damage area (P &lt; 0.05; P &lt; 0.05) and maximum diffuse damage radius (P &lt; 0.05; P &lt; 0.05), for both the entry and exit surfaces, respectively, compared with the 12 Ncm and 18 Ncm groups.Conclusions: Insertion torque can influence the degree of OM insertion and, subsequently, the amount of microdamage formed following insertion into 1.5 mm thick porcine tibia bone. An increase in insertion torque corresponds with greater insertion depth and larger amounts of microdamage.</p