University of Graz

About: University of Graz is a education organization based out in Graz, Steiermark, Austria. It is known for research contribution in the topics: Population & Quantum chromodynamics. The organization has 17934 authors who have published 37489 publications receiving 1110980 citations. The organization is also known as: Carolo Franciscea Graecensis & Karl Franzens Universität.

Continuous monitoring of in vitro oxidation of human low density lipoprotein.

Abstract: The kinetics of the oxidation of human low densit) lipoprotein (LDL) can be measured continuously by monitoring the change of the 234 nm diene absorption. The time-course shows three consecutive ph...

Röntgenuntersuchung gelöster Fadenmoleküle

Abstract: In the X-ray scattering curve of chain-molecules in solution, essentially four regions may be distinguished as is shown by a more detailed mathematical discussion: (1)The scattering at the smallest angles, showing an approximately Gaussean course, whose ordinate, when extrapolated to zero angle, is proportional to the square of the mol. weight. It is due to the diffraction effect of the whole coiled chain-molecule. (2)This is followed by a region of v-values where the scattering falls off as 1/v2. It is due to parts of the chain molecule which themselves already occur in all possible orientations. (3)After a transition region (which is also accounted for by the theory) there follows a scattering which is proportional to 1/v. It is to be considered as the scattering of mostly straight parts of the molecule. (4)The scattering at large angles, caused by smaller parts of the molecule (monomer group and single atoms), which at the same time indicates the periodicity (= length of structural unit in the direction of the chain axis) by a step, at an angle corresponding to Bragg's law. Its sharpness, too, is a measure for the coiling of the molecule. It can be shown that the abscissa of the intersecting point of the 1/v2 and 1/v branches, when extrapolated to the transition region, is connected in a characteristic way with the statistical chain element or the “length of persistance”, which represent two different measures for the stiffness of the chain molecule. Measurements with polyvinyl bromide lead to a length of persistance of 11 ± 1 A, which agrees satisfactorily with the value of 13 A for polyvinyl chloride as derived from the birefringence of flow. At large angles two weak steps were found, one of which corresponds to the monomer length of 2.56 A. Measurements on solutions of cellulose nitrate gave a curve ∼ 1/v without any steeper ascent up to the smallest angles, corresponding to 300 A. We have, therefore, to conclude that the chain-element of cellulose nitrate is in any case larger than 150 A, which again is in agreement with the results of other physical measurements. Though only a small number of experimental results is available so far, it seems to be established that the procedure yields a direct evaluation of the shape of chain molecules in solution and, in this respect, appears superior to other methods. However, the experimental difficulties are considerable.

On the shape of a set of points in the plane

Abstract: A generalization of the convex hull of a finite set of points in the plane is introduced and analyzed. This generalization leads to a family of straight-line graphs, " \alpha -shapes," which seem to capture the intuitive notions of "fine shape" and "crude shape" of point sets. It is shown that a-shapes are subgraphs of the closest point or furthest point Delaunay triangulation. Relying on this result an optimal O(n \log n) algorithm that constructs \alpha -shapes is developed.