Structure of Colored Complete Graphs Free of Proper Cycles

For a fixed integer m, we consider edge colorings of complete graphs which contain no properly edge colored cycle Cm as a subgraph. Within colorings free of these subgraphs, we establish global structure by bounding the number of colors that can induce a spanning and connected subgraph. In the case of smaller cycles, namely C4,C5, and C6, we show that our bounds are sharp

Relationship between ozone and temperature during the 2003 heat wave in France: consequences for health data analysis

BACKGROUND: PAPRICA is a research program designed to estimate the impact on the health of patients with chronic respiratory insufficiency of a prevention strategy based on notification of ozone pollution. The first year of this study was conducted during the 2003 heat wave, and high temperatures were therefore considered as a confounding factor in the data analysis. The aim of the present study was to assess the relationship between ozone and temperature in order to propose a methodology to distinguish between the effects of ozone and temperature on the impact of a prevention strategy with regard to ozone pollution. METHODS: Multivariate analyses were used to identify associated climate and ozone pollution profiles. This descriptive method is of great value to highlight the complexity of interactions between these parameters. RESULTS: Ozone concentration and temperature were strongly correlated, but the health impact of ozone pollution alone will be evaluated by focusing on situations characterized by ozone concentrations above 110 μg/m(3)/8h (air quality guidelines to protect human health defined by the French legislation) and temperatures lower than 26°C, below the discomfort threshold. CONCLUSION: The precise relationship between ambient ozone concentration and temperature identified during the PAPRICA 2003 study period will be used in analysing the PAPRICA health data

Symplectic Meanders

Analogous to the ��(n) case, we address the computation of the index of seaweed subalgebras of ��(2n) by introducing graphical representations called symplectic meanders. Formulas for the algebra’s index may be computed by counting the connected components of its associated meander. In certain cases, formulas for the index can be given in terms of elementary functions

Graph Linkedness With Prescribed Lengths

Given a multigraph H, a graph G is H-linked if every injective map f : V (H) -\u3e V (G) can be extended to an H-subdivision (f,g) in G for some g. Given a multigraph H and an integer sequence w = {we | e 2 E(H), we 2}, a graph G is (H, w, m)-linked if every injective map f : V (H) -\u3e V (G) can be extended to an H-subdivision (f,g) in G such that each path g(e) has length we ,..., or we + m. If m = 0, then we say G is (H, w)-linked. We show that the sharp minimum degree condition for a graph to be H-linked is the same as the sharp minimum degree condition for a large graph to be (H, w, m)-linked for m 1 and all sets w with each value we 2 w at least 14. Additionally, we establish a sharp minimum degree condition for a large graph to be (H, w)-linked

Integer Solutions to Box Optimization Problems

Two approaches contribute to the problem of finding integer side-lengths for open rectangular and polygonal boxes that optimize volume. One method adapts Pythagorean triples to an ellipse, while the other is based on counting factorizations

Fiber-reinforced ceramic matrix composites processed by a hybrid technique based on chemical vapor infiltration, slurry impregnation and spark plasma sintering

International audienceFabrication of multidirectional continuous carbon and silicon carbide fiber reinforced Ceramic Matrix Composites (CMC) by a new short time hybrid process was studied. This process is based, first, on the deposition of fiber interphase and coating by chemical vapor infiltration, next, on the introduction of silicon nitride powders into the fibrous preform by slurry impregnation and, finally, on the densification of the composite by Liquid-Phase Spark Plasma Sintering (LP-SPS). The homogeneous introduction of the ceramic charges into the multidirectional fiber preforms was realized by slurry impregnation from highly concentrated and well dispersed aqueous colloid suspensions. The chemical degradation of the carbon fibers during the fabrication was prevented by adapting the sintering pressure cycle. The composites manufactured are dense. Microstructural analyses were conducted to explain the mechanical properties achieved. One main important result of this study is that LP-SPS can be used in some hybrid processes to densify fiber reinforced CMC