Dreiphasige Emulsionen

Ohne Zusammenfassung     

Zur Hydrodynamik von Systemen veränderlicher Viskosität,III

Ohne Zusammenfassung     

Analysis of human brain tissue, brain tumors and tumor cells by infrared spectroscopic mapping

This study uses infrared (IR) spectroscopic, point detection, mapping procedures to examine tissue samples from normal brain specimens and from astrocytic gliomas, the most frequent human brain tumors. Model systems were derived from cultured glioma cell lines. IR spectra of normal tissue sections distinguished white matter from gray matter by increased spectral contributions from lipids and cholesterol. Qualitatively the same differences were found in IR spectra of low and high grade glioma tissue sections pointing to a significant reduction of brain lipids with increasing malignancy. Whereas spectral contributions of proteins and lipids were similar in IR spectra of glioma cells and tissues, nucleic acid bands were more intense for cells suggesting higher proliferative activities. For statistical analyses of IR spectroscopic maps from 71 samples, a parameter for the lipid to protein ratio was introduced involving the CH(2) symmetric stretch band with lipids as main contributors and the amide I band of proteins. As this parameter correlated with the grade of gliomas obtained from standard histopathological examination, it was applied to classify brain tissue sections based on IR spectroscopic mapping.     

Visibility Complexes and the Baues Problem for Triangulations in the Plane

We give a positive answer for the special case of the Generalized Baues Problem which asks whether the complex of triangulations of a point set A in general position in the plane has the homotopy type of a sphere. In the process, we are led to define the visibility complex for a simplicial complex P whose vertices lie in A , and prove that this visibility complex has the same homotopy type as P . The main technique is a variant of deletion-contraction from matroid theory, along with a new method for proving homotopy equivalence of posets which we call the nerve-flag paradigm. Received January 23, 1997, and in revised form June 20, 1997.