How to Get 3-D for the Price of 2-D—Topology and Consistency of 3-D Urban GIS

This article deals with topological concepts and models which are necessary to represent three-dimensional urban objects in a geographical information system (GIS). Depending on the shape and the representation of features, several classes with increasing topological complexity are identified and described. This complexity has strong impacts on the models and tools which are required to represent, manage and edit the data. One specific model we call 2.8-D map is identified, which covers many 3-D applications in GIS. It is a slight extension of a 2-D or 2.5-D model and preserves the algorithmic and conceptual simplicity of the 2-D case as much as possible. The model is described in a formal way. Integrity axioms are given, which detect errors in corresponding data sets safely and guarantee the consistency of 2.8-D maps in a mathematically sound and provable way. These axioms are effectively and efficiently checkable by automatic procedures. The model extends digital terrain models (2.5-D) by allowing for vertical walls and projections like balconies or ledges. The conceptual simplicity is due to the two-dimensional topology of the model. Thus bridges and tunnels are special cases; it is shown how to detect and handle these cases efficiently. Based on this model, thematic objects and their aggregation structures are defined in a consistent way.     

Acyl transfer in clorobiocin biosynthesis: involvement of several proteins in the transfer of the pyrrole-2-carboxyl moiety to the deoxysugar

Clorobiocin is an aminocoumarin antibiotic containing a pyrrole-2-carboxyl moiety, attached through an ester bond to a deoxysugar. The pyrrole moiety is important for the binding of the antibiotic to its biological target, gyrase. The complete biosynthetic gene cluster for clorobiocin has been cloned and sequenced from the natural producer, Streptomyces roseochromogenes DS 12.976. In this study, the genes cloN1 and cloN7 were deleted separately from a cosmid containing the complete clorobiocin cluster. The modified cosmids were introduced into the genome of the heterologous host Streptomyces coelicolor M512 by using the integration functions of the PhiC31 phage. While a heterologous producer strain harbouring the intact clorobiocin biosynthetic gene cluster accumulated clorobiocin, the cloN1- and cloN7-defective integration mutants accumulated a clorobiocin derivative that lacked the pyrrole-2-carboxyl moiety, while also producing free pyrrole-2-carboxylic acid. The structures of these metabolites were confirmed by NMR and MS analysis. These results showed that CloN1 and CloN7, together with the previously investigated CloN2, are involved in the transfer of the pyrrole-2-carboxyl moiety to the deoxysugar of clorobiocin. A possible mechanism for the role of these three proteins in the acyl-transfer process is suggested.     

Sensitivities of impedance scaled SC filters

A crucial effect of frequency dependent scaling of impedances on the frequency response is discussed. The essential point is illustrated by means of a simple RC lowpass simulation.     

An efficient bifunctional lithium-organic initiator to be used in apolar solvents

Upon reaction of m-diisopropenylbenzene (DIB) with two mole equivalents of s-butyllithium (BuLi) in benzene solution a diadduct is formed predominantly. It was identified by proton n.m.r. and by mass spectrometry. Some oligomers are formed, next to the diadduct, at the expense of the monoadduct. When the addition reaction is carried out to completion, precipitation eventually occurs. If this solution is used as it is formed, before precipitation has occurred, to initiate the polymerization of styrene or of dienes in non-polar solvents, the polymers formed exhibit the molecular weights expected, narrow molecular weight distributions and two lithium-organic sites per polymer chain. This bifunctional lithium-organic initiator is efficient, in the absence of any polar additive, and should find suitable applications for the synthesis of triblock copolymers, of model networks and of telechelic polymers.     

X-ray powder diffraction data on salts of α-sulfonated long chain acids

This paper reports x-ray powder diffraction study for twentyfour salts of α-sulfonated normal long chain fatty acids. Acid and neutral sodium, potassium lithium, cesium, calcium, magnesium, and triethanolammonium salts of α-sulfolauric, myristic, palmitic, stearic, and behenic acids were examined. The method can be used to identify and distinguish the individual salts and has possible application to the analysis of mixtures.     

Texturen in Warmband aus mikrolegierten Stählen

Untersuchung von Texturen in Querschnittsmitte und an der Oberfläche von mikrolegiertem Warmband unterschiedlicher chemischer Zusammensetzung. Vergleich mit Texturen in unlegiertem Warmband. Prüfung der Beständigkeit der Texturen bei Wärmebehandlungen. Deutung der Texturentstehung. Einfluß der Textur auf die Verarbeitungs- und Gebrauchseigenschaften von Warmband.     

Transient Species in the Laser Photolysis at 265 Mμ of the Halogenobenzenes in Solution

Pulsing cyclohexane or methanol-water solutions of chlorobenzene and fluorobenzene with the Nd laser at 265 mμ (half-height width 30 nsec) gives rise to intermediates, absorbing in the 290–300 mμ region, attributed to the corresponding triplet states. The decay of the triplet states is roughly first order with rate constants of (2.1 ± 0.1) × 10⁶ sec^?1 and (1.5 ± 0.1) × 10⁶ sec^?1 respectively. No transient absorption was observed with bromo- and iodobenzene under the same conditions. Solutions of the two latter compounds containing KI or KBr show the appearance of I^?₂ or IBr^? following laser excitation.