Simple and Robust Boolean Operations for Triangulated Surfaces

Boolean operations of geometric models is an essential issue in computational geometry. In this paper, we develop a simple and robust approach to perform Boolean operations on closed and open triangulated surfaces. Our method mainly has two stages: (1) We firstly find out candidate intersected-triangles pairs based on Octree and then compute the inter-section lines for all pairs of triangles with parallel algorithm; (2) We form closed or open intersection-loops, sub-surfaces and sub-blocks quite robustly only according to the cleared and updated topology of meshes while without coordinate computations for geometric enti-ties. A novel technique instead of inside/outside classification is also proposed to distinguish the resulting union, subtraction and intersection. Several examples have been given to illus-trate the effectiveness of our approach.Comment: Novel method for determining Union, Subtraction and Intersectio

The Modified Direct Method: an Approach for Smoothing Planar and Surface Meshes

The Modified Direct Method (MDM) is an iterative mesh smoothing method for smoothing planar and surface meshes, which is developed from the non-iterative smoothing method originated by Balendran [1]. When smooth planar meshes, the performance of the MDM is effectively identical to that of Laplacian smoothing, for triangular and quadrilateral meshes; however, the MDM outperforms Laplacian smoothing for tri-quad meshes. When smooth surface meshes, for trian-gular, quadrilateral and quad-dominant mixed meshes, the mean quality(MQ) of all mesh elements always increases and the mean square error (MSE) decreases during smoothing; For tri-dominant mixed mesh, the quality of triangles always descends while that of quads ascends. Test examples show that the MDM is convergent for both planar and surface triangular, quadrilateral and tri-quad meshes.Comment: 18 page

Acid-soluble spore proteins of Bacillus subtilis

Acid-soluble spore proteins (ASSPs) comprise about 5% of the total protein of mature spores of different Bacillus subtilis strains. They consist of three abundant species, alpha, beta, and gamma, four less abundant species, and several minor species, alpha, beta, and gamma make up about 18, 18 and 36%, respectively, of the total ASSPs of strain 168, have molecular weights of 5,900, 5,9000, and 11,000, respectively, and resemble the major (A, C, and B) components of Bacillus megaterium ASSPs in several respects, including sensitivity to a specific B. megaterium spore endopeptidase. However, they have pI\u27s of 6.58, 6.67, and 7.96, all lower than those of any of the B. megaterium ASSPs. Although strains varied in the proportions of different ASSPs, to overall patterns seen on gel electrophoresis are constant. ASSPs are located interior to the cortex, presumably in the spore cytoplasm, and are synthesized during sporulation and degraded during germination

Predictive person models elicit motor biases: The face-inhibition effect revisited

Using an established paradigm, we tested whether people derive motoric predictions about an actor’s forthcoming actions from prior knowledge about them and the context in which they are seen. In two experiments, participants identified famous tennis and soccer players using either hand or foot responses. Athletes were shown either carrying out or not carrying out their associated actions (swinging, kicking), either in the context where these actions are typically seen (tennis court, soccer Pitch) or outside these contexts (beach, awards ceremony). Replicating prior work, identifying non-acting athletes revealed the negative compatibility effects: viewing tennis players led to faster responses with a foot than a hand, and vice versa for viewing soccer players. Consistent with the idea that negative compatibility effects result from the absence of a predicted action, these effects were eliminated (or reversed) when the athletes were seen carrying out actions typically associated with them. Strikingly, however, these motoric biases were not limited to In-Context trials but were, if anything, more robust in the Out-of-Context trials. This pattern held even when attention was drawn specifically to the context (Experiment 2). These results confirm that people hold motoric knowledge about the actions that others typically carry out and that these actions are part of perceptual representations that are accessed when those others are re-encountered, possibly in order to resolve uncertainty in person perception

Sex differences in eye gaze and symbolic cueing of attention

Observing a face with averted eyes results in a reflexive shift of attention to the gazed-at location. Here we present results that show that this effect is weaker in males than in females (Experiment 1). This result is predicted by the ‘extreme male brain’ theory of autism (Baron-Cohen, 2003), which suggests that males in the normal population should display more autism-like traits than females (e.g., poor joint attention). Indeed, participants′ scores on the Autism-Spectrum Quotient (Baron-Cohen, Wheelwright, Stott, Bolton, & Goodyear, 2001) negatively correlated with cueing magnitude. Furthermore, exogenous orienting did not differ between the sexes in two peripheral cueing experiments (Experiments 2a and 2b). However, a final experiment showed that using non-predictive arrows instead of eyes as a central cue also revealed a large gender difference. This demonstrates that reduced orienting from central cues in males generalizes beyond gaze cues. These results show that while peripheral cueing is equivalent in the male and female brains, the attention systems of the two sexes treat noninformative symbolic cues very differently

Influence of hand position on the near-effect in 3D attention

Voluntary reorienting of attention in real depth situations is characterized by an attentional bias to locations near the viewer once attention is deployed to a spatially cued object in depth. Previously this effect (initially referred to as the ‘near-effect’) was attributed to access of a 3D viewer-centred spatial representation for guiding attention in 3D space. The aim of this study was to investigate whether the near-bias could have been associated with the position of the response-hand, always near the viewer in previous studies investigating endogenous attentional shifts in real depth. In Experiment 1, the response-hand was placed at either the near or far target depth in a depth cueing task. Placing the response-hand at the far target depth abolished the near-effect, but failed to bias spatial attention to the far location. Experiment 2 showed that the response-hand effect was not modulated by the presence of an additional passive hand, whereas Experiment 3 confirmed that attentional prioritization of the passive hand was not masked by the influence of the responding hand on spatial attention in Experiment 2. The pattern of results is most consistent with the idea that response preparation can modulate spatial attention within a 3D viewer-centred spatial representation