THE CHEMILUMINESCENCE OF INDOLE DERIVATIVES IN DIMETHYL SULFOXIDE*

The chemiluminescent autoxidation of over fifty indoles has been measured in dimethyl sulfoxide (DMSO). The 3-alkylindole derivatives represent the brightest and most efficient members of this group. The chemiluminescence yield (per mole) of skatole is (1·5 ± 0·6) × 10^-3. The chemiluminescence spectrum of skatole is identical with the fluorescence spectrum of o-formamidoacetophenone in the same environment Similar results for 2,3-dimethylindole lead to the identification of the acylamide anion as the emitter in indole chemiluminescence. A peroxide ring cleavage excitation mechanism is proposed.     

Finite Element Analyses in Surface Water and Groundwater: An Overview of Investigations at the U.S. Army Engineer Waterways Experiment Station

This paper highlights the finite element hydrodynamic and transport modeling developments being conducted by the U.S. Army Engineer Waterways Experiment Station (WES) and its partnering organizations. The WES developments in support of surface water, groundwater, and watershed management are presented. A particular facet of these developments, the creation of integrated, comprehensive modeling systems which greatly increase the productive use of WES hydroenvironmental models, is discussed. Future development directions, including the use of scalable high performance computing resources, are also provided.     

TOWARDS A STANDARD FOR THE INDIVIDUAL‐BASED MODELING OF PLANT POPULATIONS: SELF‐THINNING AND THE FIELD‐OF‐NEIGHBORHOOD APPROACH

ABSTRACT. In classical theoretical ecology there are numerous standard models which are simple, generally applicable, and have well‐known properties. These standard models are widely used as building blocks for all kinds of theoretical and applied models. In contrast, there is a total lack of standard individual‐based models (IBM's), even though they are badly needed if the advantages of the individual‐based approach are to be exploited more efficiently. We discuss the recently developed ‘field‐of‐neighborhood’ approach as a possible standard for modeling plant populations. In this approach, a plant is characterized by a circular zone of influence that grows with the plant, and a field of neighborhood that for each point within the zone of influence describes the strength of competition, i.e., growth reduction, on neighboring plants. Local competition is thus described phenomenologically. We show that a model of mangrove forest dynamics, KiWi, which is based on the FON approach, is capable of reproducing self‐thinning trajectories in an almost textbook‐like manner. In addition, we show that the entire biomass‐density trajectory (bdt) can be divided into four sections which are related to the skewness of the stem diameter distributions of the cohort. The skewness shows two zero crossings during the complete development of the population. These zero crossings indicate the beginning and the end of the self‐thinning process. A characteristic decay of the positive skewness accompanies the occurrence of a linear bdt section, the well‐known self‐thinning line. Although the slope of this line is not fixed, it is confined in two directions, with morphological constraints determining the lower limit and the strength of neighborhood competition exerted by the individuals marking the upper limit.