Adaptive spline surface fitting with arbitrary topological control mesh.

Reconstructing a spline surface from a given arbitrary topological triangle mesh is a fundamental and challenging problem in computer-aided design and engineering. This paper introduces a novel surface fitting method utilizing G-NURBS capable of handling control meshes with arbitrary topologies. This method employs adaptive control point adjustment, guided by the geometric attributes of the input model, ensuring precise representation of sharp features such as edges and corners. Two primary strategies are employed: a parameter correspondence approach designed for sharp features and a control mesh iterative refinement technique that incorporates geometrical feature information. The proposed method has been tested and evaluated on various CAD models to demonstrate its effectiveness. This method can achieve higher fitting accuracy while faithfully preserving the geometrical features with fewer control points.

Patching Non-Uniform Extraordinary Points.

Smooth surfaces from an arbitrary topological control grid have been widely studied, which are mostly generalized from splines with uniform knot intervals. These methods fail to work well on extraordinary points (EPs) whose edges have varying knot intervals. This paper presents a patching solution for arbitrary topological 2-manifold control grid with non-uniform knots that defines one bi-cubic Bézier patch per control grid face except those faces with EPs. Experimental results demonstrate that the new solution can improve the surface quality for non-uniform parameterization. Applications in surface reconstruction, arbitrary sharp features on the complex surface and tool path planning for the new surface representation are also provided in the paper.

A framework from point clouds to workpieces.

Combining computer-aided design and computer numerical control (CNC) with global technical connections have become interesting topics in the manufacturing industry. A framework was implemented that includes point clouds to workpieces and consists of a mesh generation from geometric data, optimal surface segmentation for CNC, and tool path planning with a certified scallop height. The latest methods were introduced into the mesh generation with implicit geometric regularization and total generalized variation. Once the mesh model was obtained, a fast and robust optimal surface segmentation method is provided by establishing a weighted graph and searching for the minimum spanning tree of the graph for extraordinary points. This method is easy to implement, and the number of segmented patches can be controlled while preserving the sharp features of the workpiece. Finally, a contour parallel tool-path with a confined scallop height is generated on each patch based on B-spline fitting. Experimental results show that the proposed framework is effective and robust.

Heparin for patients with growth restricted fetus: a prospective randomized controlled trial.

OBJECTIVE: Heparin was hypothesized to facilitate the growth of the growth-restricted fetus. Our study was to assess the efficiency of heparin in treating fetus with growth restriction and to explore the possible mechanisms. METHODS: Seventy-three pregnant women were selected in this study. Based on regular treatments, patients randomly received either heparin or dan-shen combined with low-molecular weight dextrose. A serial ultrasonography and hematological measurements were performed on each patient at the enrolment and 7 days after the first treatment. Neonatal birth weight, 1-min Apgar score and gestational age were recorded. Placentas were collected for apoptotic indices. RESULTS: Heparin significantly improved maternal hemorrheological indices, fetal growth velocities and neonatal outcomes. It also reduced apoptosis in trophoblasts. CONCLUSIONS: Our results provide evidence that heparin significantly improves the growth of the growth-restricted fetus. The growth improvement is probably achieved by the changes in maternal hemorrheology and the attenuated apoptosis in trophoblasts.

[Effect of heparin on umbilical blood flow in patients with fetal growth retardation].

OBJECTIVE: To investigate the effect of heparin on umbilical blood flow in pregnant women with fetal growth retardation (FGR). METHODS: A total of 103 FGR women were randomized into control group (n=37), standard heparin group (n=35) and low-molecular-weight heparin group (n=31). Low-molecular-weight dextran was given in the control group, and the other two groups received agents for intervention as indicated. The umbilical blood flow, 1-minute Apgar score, body weight and gestational age of the neonates were measured and compared between the 3 groups. RESULTS: As the gestational age increases, the systolic/diastolic (S/D) ratio, pulsatility index (PI) and resistance index (RI) were significantly lowered in the two heparin groups in comparison with those in the control group (P<0.05). One-minute Apgar score and body weight of the neonates were significantly greater in the two heparin groups (P<0.05), and the gestational age was also significantly longer (P<0.05). No statistical differences in the indices measured were noted between the two heparin groups (P>0.05). CONCLUSIONS: Heparin, which is safe for both the mothers and their fetuses, might improve fetal growth and development, increase neonate body weight, prolong the gestational age and raise the one-minute Apgar score.

[Effect of heparin on fetal growth restriction].

OBJECTIVE: To investigate the clinical effect and safety of heparin in treating fetal growth restriction (FGR). METHODS: A total of 107 women diagnosed with FGR were randomized into three groups. Group 1 (standard heparin group, n = 37) received 50 - 75 mg standard heparin added to 500 ml 5% glucose sodium chloride, infused intravenously in 6 - 8 hours. Group 2 (low molecular weight heparin group, n = 31) received 0.2 - 0.4 ml low molecular weight heparin given by subcutaneous injection. Control group (n = 39) received 20 ml dan-shen added to 500 ml low-molecular-weight dextran infused intravenously. Fetal growth indices, biophysical score, umbilical artery blood flow, count of platelet (PLT), prothrombin time (PT), activated partial thromboplastin time (APTT), 1-minute Apgar score, body weight and gestational age of the neonates were measured. Babies prognosis was followed-up. RESULTS: (1) Height of fundus of uterus was obviously increased per week in the groups of standard heparin (0.7 +/- 0.6) cm and low molecular weight heparin [(0.7 +/- 0.6) cm]] vs. control group [(0.5 +/- 0.4) cm, P < 0.05]. Biparietal diameter of fetus increased in standard heparin [(2.4 +/- 0.7) mm] and low molecular weight heparin [(2.5 +/- 0.8) mm] groups vs. control [(1.7 +/- 0.6) mm, P < 0.05]. The femur length, head circumference and abdominal circumference of fetus were significantly longer in heparin treated patients than in control group (P < 0.05). (2) Biophysical score improved in groups of standard heparin (9.7 +/- 0.8) and low molecular weight heparin (9.6 +/- 0.6) vs. control group (8.9 +/- 0.7) (P < 0.05). (3) Umbilical blood S/D ratio decreased in standard heparin (2.5 +/- 0.5) and low molecular weight heparin (2.4 +/- 0.5) groups vs. control group (2.9 +/- 0.6) (P < 0.05). Pulsatile index (PI) and resistance index (RI) were significantly lower also (P < 0.05).(4) Rate of one minute Apgar score (8 - 10) was 86% in group 1, 87% in group 2 and 74% in control group, respectively. Body weight of the neonates was significantly increased in group 1(3100 +/- 256 g) and in group 2 [(3080 +/- 225) g] vs. [(2580 +/- 304) g] in control group (P < 0.05). Gestational age was prolonged in group 1 [(38 +/- 3) w] and group 2 [(38 +/- 4) w] vs. control group [(37 +/- 4) w, P < 0.05]. (5) Incidence of term small for gestational age infant in groups of standard heparin and low molecular weight heparin was 5% and 6%, respectively, significantly lower than those in the control group (18%) (P < 0.05). (6) No difference was shown in PLT, PT and APTT before and after heparin treatment (P > 0.05). (7) There was no difference in fetal growth indices, biophysical score, umbilical blood, neonatal outcome between standard heparin and low molecular heparin groups. CONCLUSIONS: Heparin can improve placenta function and obviously increase body weight of fetuses and neonates. It is safe for both pregnant women and their fetuses.

[Relationship between pathological changes and the expression of vascular cell adhesion molecule-1 in the placenta of patients with pregnancy-induced hypertension complicated by intrauterine growth retardation].

OBJECTIVE: To study the relationship of the pathological changes with the expression of vascular cell adhesion molecule-1(VCAM-1) in the placenta of patients with pregnancy-induced hypertension (PIH) that is complicated by intrauterine growth retardation (IUGR). METHODS: Tissue specimens of the placenta were respectively collected from 30 patients with PIH complicated by IUGR, 28 patients with IUGR, 25 patients with PIH and 30 normal women after delivery. After HE and PAS staining, the tissue sections were observed microscopically to detect morphological changes in the placenta. Immunohistochemical examination was employed to detect the expression of the VCAM-1 in the decidual vascular endothelium, syncytiotrophoblast and villous capillary vessel of the placenta in these tissue specimens. RESULTS: Significant pathological changes were observed in 22 placentas of the patients with PIH complicated by IUGR, with the incidence of 73.33 %. The pathological changes exemplified by stromal fibrosis, fibrinoid necrosis and leucocyte infiltration of the villi, increase in villous syncytial nodules, decrease in villous vascular tissues, hyperplasia of cytotrophoblasts and basal lamina thickening were more prevalent in the placentas of patients with PIH complicated by IUGR than in normal women (P<0.05). The expression of VCAM-1 in the decidual vascular endothelium and placental villous capillary vessels was observed to be significantly higher in the placentas with pathological changes than in those without (P<0.05), which was the opposite to the changes in the expression in the syncytiotrophoblast (P<0.05). CONCLUSION: Significant pathological changes can be present in the placenta of patients with PIH complicated by IUGR, and may be intimately related to abnormal expressions of VCAM-1 in the placenta.