3-D segmentation of MR images of the head for 3-D display

Algorithms for 3-D segmentation and reconstruction of anatomical surfaces from magnetic resonance imaging (MRI) data are presented. The 3-D extension of the Marr-Hildreth operator is described, and it is shown that its zero crossings are related to anatomical surfaces. For an improved surface definition, morphological filters-dilation and erosion-are applied. From these contours, 3-D reconstructions of skin, bone, brain, and the ventricular system can be generated. Results obtained with different segmentation parameters and surface rendering methods are presented. The fidelity of the generated images comes close to anatomical reality. It is noted that both the convolution and the morphological filtering are computationally expensive, and thus take a long time on a general-purpose computer. Another problem is assigning labels to the constituents of the head; in the current implementation, this is done interactively.     

Oxidative Coupling of Poly (2-Vinylthiophene) Chains by FeCl3

Summary Poly(2-vinylthiophene) (PVT) can be cross linked with FeCl₃ either in dichloromethane solution or when immobilized on silica particles. Extend of cross linking is strongly dependent on the FeCI₃/PVT ratio used for the reaction as shown by GPC plots and gravimetric analyses of the formed insoluble polymer fraction. A stoichiometric FeCl₃/PVT ratio of about four is necessary to achieve complete conversion, because consecutive formations of thiophene H⁺FeCl₄ ^- and bisthiophene H⁺FeCl₄ ^- sigma complexes take place. PVT can be also cross linked when adsorbed on silica using the same procedure. The cross-linking is proved by IR and ¹³C CPiMAS NMR spectroscopy.     

Interaction between a Fab fragment against gp41 of human immunodeficiency virus 1 and its peptide epitope: characterization using a peptide epitope library and molecular modeling

The molecular interaction of the Fab fragment of the human monoclonalantibody 3D6, directed against the transmembrane protein gp41of human immunodeficiency virus (HTV) 1, with its peptide epitopeis characterized by a panel of overlapping peptides, a peptideepitope library and molecular modeling techniques. The sequenceCSGKLICTTAVPW, corresponding to amino acids 605–617 ofgp41, was identified as the best binding peptide (K_D = 1x10^-8mol/1). This peptide served as a starting point to prepare acellulose-bound peptide epitope library in which each residueof the epitope is substituted by all L- and D-amino acids, resultingin 494 epitope peptide variants which were subsequently analyzedfor binding 3D6. The library was synthesized to identify residuescritical for binding and to obtain information about the molecularenvironment of the epitope peptide bound to 3D6. Both cysteineresidues, as well as isoleucine 6, threonine 8 and proline 12,of the epitope were highly sensitive to substitution. Usingthe data obtained from the epitope characterization, as wellas a low-resolution electron density map of a 3D6 Fab-peptidecomplex, a 3-D model of the Fab-peptide complex was generatedby molecular modeling. The modeling experiments predict bindingof the peptide, which is cyclized via the two cysteine residues,to a pocket formed dominantly by the hypervariable loops complementaritydetermining regions CDR3L, CDR2H and CDR3H.     

A `virtual body' model for surgical education and rehearsal

A general digital model of human anatomy is very helpful both in supporting the process of anatomical segmentation and as a reference system for simulating surgical situations or even rehearsal of interventions. This article describes the data structure and implementation of such a model. Neither superhero nor crash-test dummy, Voxel-Man is an attempt to combine in a single framework a detailed spatial model enabling realistic visualization with a symbolic model of the human body. We show that although a general model does not correspond in detail to an individual patient, it does provide a variety of novel features for surgical education and training     

日间托儿园,柏林

这是一栋为人们每日提供服务的重要的公共建筑.其特别的功能要求,与常见的建筑形式有很大不同.本幼儿园在平面用地上受到了严格的限制,在竖向和横向的空间设计上也很复杂.较暗的小房间和走廊与位于平台和操场边缘的明亮的房间交替布置.可以把台阶形的建筑外形当作孩子们爬山的一种象征符号.左右两部楼梯朝向正立面,沿着外墙布置,把人从大门一直引到建筑上层,与房间紧密结合形成一栋紧凑、高密度的建筑,反衬出平台和室外空间的空旷,使室外儿童活动场地在视觉上感觉被扩大了.     

Shading 3D-Images from CT Using Gray-Level Gradients

For the 3D-reconstruction of organ surfaces from tomograms, a shading method based on the partial volume effect is presented. In contrast to methods based on the depth and/or the angle of the voxel surface, here the gray-level gradient along the surface is used for shading. It is shown, that at least for bone and soft tissue surfaces, the results are superior to conventional shading. This is due to the high dynamic range of the gray levels within a small spatial neighborhood.     

Visualization blackboard: visualizing the visible human

Visualization of the human body and its inner structure has challenged artists and scientists for centuries. For 500 years, since Leonardo da Vinci, drawings have been the main resource for learning anatomy because they allow the mixture of realism and abstraction suitable for didactic purposes. With the discovery of X-rays 100 years ago, it became possible to look into the living body. Only since the 1970s have computer tomography (CT) and magnetic resonance imaging (MRI) made it possible to acquire image data in three dimensions. Based on these techniques, 3D computer graphics generated the first models of the living body. These represent a tremendous advance for diagnosis and surgical planning, but the resolution is still poor when viewed from an anatomist's point of view. The National Library of Medicine's Visible Human Project provided much more realistic data-the Visible Human data set, created at the University of Colorado School of Medicine. This project produced transverse cross sectional photographic images of a male cadaver with a resolution of 0.33 mm and slice distance of 1 mm