Colouring (Pr + Ps)-Free Graphs

The k-Colouring problem is to decide if the vertices of a graph can be coloured with at most k colours for a fixed integer k such that no two adjacent vertices are coloured alike. If each vertex u must be assigned a colour from a prescribed list L(u)⊆{1,…,k}, then we obtain the List k-Colouring problem. A graph G is H-free if G does not contain H as an induced subgraph. We continue an extensive study into the complexity of these two problems for H-free graphs. The graph Pr+Ps is the disjoint union of the r-vertex path Pr and the s-vertex path Ps. We prove that List 3-Colouring is polynomial-time solvable for (P2+P5)-free graphs and for (P3+P4)-free graphs. Combining our results with known results yields complete complexity classifications of 3-Colouring and List 3-Colouring on H-free graphs for all graphs H up to seven vertices

Colouring (Pr+Ps)-free graphs.

The k-Colouring problem is to decide if the vertices of a graph can be coloured with at most k colours for a fixed integer k such that no two adjacent vertices are coloured alike. If each vertex u must be assigned a colour from a prescribed list L(u) subseteq {1,...,k}, then we obtain the List k-Colouring problem. A graph G is H-free if G does not contain H as an induced subgraph. We continue an extensive study into the complexity of these two problems for H-free graphs. We prove that List 3-Colouring is polynomial-time solvable for (P_2+P_5)-free graphs and for (P_3+P_4)-free graphs. Combining our results with known results yields complete complexity classifications of 3-Colouring and List 3-Colouring on H-free graphs for all graphs H up to seven vertices. We also prove that 5-Colouring is NP-complete for (P_3+P_5)-free graphs

Veränderungen des trans 2-Hexenal-Gehalts in Rebblättern während der Vegetationsperiode

Ungesättigte Fettsäuren sind in der Rebe Vorstufen einer biologisch wichtigen Gruppe, der ungesättigten C6-Alkohole und -Aldehyde, die Bestandteile eines typischen Aromas ("green grass flavour") sind. Außer den charakteristischen sensorischen Eigenschaften schützen diese Verbindungen die Rebe vor Pilz- oder Bakterieninfektionen. Die saisonalen Veränderungen des trans 2-Hexenal-Gehalts von Rebblättern wurden von Mai bis August 1994 bei sieben verschiedenen Rebsorten untersucht. Der höchste Wert wurde Ende Juli, zu Beginn des Traubenschlusses bei der Sorte Irsay Oliver mit 4,1 g/kg Trockensubstanz festgestellt.Investigation of the trans 2-hexenal content in leaves of grapevines during the vegetation periodUnsaturated fatty acids in plants are known to be precursors of the biologically important group of unsaturated C6-alcohols and C6-aldehydes. These compounds constitute the basis of aroma components called ''green grass flavour''. On the other hand they protect grapevines against fungal or bacterial infections. Seasonal changes of the content of trans 2-hexenal in leaves of seven varieties of Vitis vinifera were investigated from May to August 1994. The highest content of trans 2-hexenal was detected in leaf samples harvested in the last decade of July when clusters started to close (cv. Irsay Oliver 4.1 g/kg dry weight)

Calculation and measurement of a neutral air flow velocity impacting a high voltage capacitor with asymmetrical electrodes

This paper deals with the effects surrounding phenomenon of a mechanical force generated on a high voltage asymmetrical capacitor (the so called Biefeld-Brown effect). A method to measure this force is described and a formula to calculate its value is also given. Based on this the authors derive a formula characterising the neutral air flow velocity impacting an asymmetrical capacitor connected to high voltage. This air flow under normal circumstances lessens the generated force. In the following part this velocity is measured using Particle Image Velocimetry measuring technique and the results of the theoretically calculated velocity and the experimentally measured value are compared. The authors found a good agreement between the results of both approaches

Änderungen des Aminosäuregehaltes während der Schaumweinbildung

Die Änderung des Aminosäurengehaltes in Sektproben wurde 2, 12 und 24 Monate nach Beginn der Flaschengärung untersucht. Zum Start der sekundäen Gärung wurden zwei ethanoltolerante Saccharomyces cerevisiae - Stämme und drei aktive Trockenhefepräparate verwendet. Nach zwei Monaten konnte ein Konzentrationsrückgang des Großteils der Aminosäuren festgestellt worden. Nur Phenylalanin und Histidin batten zugenommen. Nach 12 Monaten war die Konzentration von Serin, Glycin, Alanin und Valin herabgesetzt, Prolin dagegen angereichert, ebenso wie Leucin und Histidin. Nach zwei Jahren war der Gehalt an Thyrosin, Histidin und Lysin, Leucin und Isoleucin erhöht, während eine Tendenz zur Verringerung der Konzentration von Prolin, Valin und Arginin registriert wurde. Die essentielle Aminosäure Methionin war nach 24 Monaten in allen Sektproben verbraucht.Changes of the amounts of amino acids during sparkling wine productionChanges of the amino acid content after 2, 12 and 24 months in sparkling wine samples have been investigated. Two liquid and three active dry wine yeast preparations of Saccharomyces cerevisiae strains were used for the secondary fermentation. After two months a decrease of most amino acids was observed, only the histidine content was increased. The concentration of serine, glycine, alanine and valine decreased after 12 months. In this phase, on the other hand, the proline, leucine and histidine contents increased. After two years the content of thyrosine, histidine and lysine as well as leucine and isoleucine in sparkling wines raised, while proline, valine and asparagine showed a decrease compared with the initial concentrations. The essential amino acid methionine was utilized in all sparkling wine samples after 24 months