Narrowing of the balance function with centrality in Au plus Au collisions at root s(NN)=130 GeV

The balance function is a new observable based on the principle that charge is locally conserved when particles are pair produced. Balance functions have been measured for charged particle pairs and identified charged pion pairs in Au+Au collisions at roots(NN)=130 GeV at the Relativistic Heavy Ion Collider using STAR. Balance functions for peripheral collisions have widths consistent with model predictions based on a superposition of nucleon-nucleon scattering. Widths in central collisions are smaller, consistent with trends predicted by models incorporating late hadronization

The volume distribution of Tetrahymena elliotti: Its measurement, and application to growth parameter estimation.

The volume distribution of a population of cells growing by binary fission is considered practically and theoretically. A mathematical model of the volume distribution of extant cells in a growing population is derived and compared to volume distributions obtained by optical means and by use of a Coulter counter. The model has the same form as distributions obtained optically, but is substantially different from those measured with the Coulter counter. An examination of the mode of operation of the Coulter counter shows that its physical configuration leads to excessive skewness in the measured distributions. The use of an hydrodynamic focusing system produces distributions which agree in form with both the theoretical model and the optically derived volume distributions. The Coulter counter has been shown to underestimate the size of ciliates. The apparent shrinkage of the cells after dilution with saline solution is thought to be due to the permiability of the cell pellicle to electrical current. The mean size of cells measured with the Coulter counter is linearly related to the size measured microscopically. A novel method of assessing the skewness of volume distributions is developed. The relationship of skewness to growth rate is determined and discussed. The relationship between the mitotic index and the growth rate is derived for the first time. The batch growth of Tetrahymena elliotti has been studied in depth, and. it has been demonstrated that no stationary phase, in the classical sense, is developed. It is shown that there is significant cell cell death in cultures of T. elliotti, particularly in relation to sparged aeration and magnetic stirring. Continuous culture of T. elliotti failed to achieve steady states, whereas other microorganisms (T. pyriformis and Klebsiella pneumoniae) came to steady state in the same apparatus

Rough Set Approximation as formal concept

Formal Concept Analysis (FCA) defines a formal concept as a pair of sets: objects and attributes, called extent and intent respectively. A rough set, on the other hand, approximates a concept using sets of objects only (in terms of FCA). We show that 1) a formal concept can be composed using a set of objects and its complement, 2) such object-based formal concepts are isomorphic to formal concepts based on objects and attributes, 3) upper and lower approximations of rough sets give generalization of formal concept, and 4) the pair of positive and negative sets (sensu rough set theory) are isomorphic to complemental formal concepts when the equivalence of the rough set gives positive and negative sets unique to each of the formal concepts. Implications of this are discussed

Nomencurator: a nomenclatural history model to handle multiple taxonomic views

Evolutionary studies are generating increasing numbers of phylogenies which, in turn, sometimes result in changes to hierarchical organization and therefore changes in taxonomic nomenclature. A three-layered data model for a nomenclature database has been developed in order to elucidate the information structure in nomenclature and as a means to organize and manage a large, dynamic knowledge-base. In contrast to most other taxonomic databases, the model is publication-oriented rather than taxon-oriented and dynamic rather than static, in order to mimic the processes that taxonomists use naturally. The three-layered structure requires data integrity localized to each publication, instead of global data integrity, which relaxes constraints common to taxonomic databases and permits multiple taxonomic opinions: taxon names are made available as metadata within the model. Its prototype implementation, written in C++, has an autonomous self-identification mechanism to avoid spurious data-inflation in a publication-oriented data model. Self-identification is also desirable for distributed implementations of the nomenclature database. Publication-oriented design also will make maintenance easier than for taxon-oriented databases, much of the maintenance workload being amenable to automation. The three-layered data model was designed for use by taxonomists, but is also able to provide concise, reduced expression for non-experts required in biodiversity research, for example

Comparison of multiple taxonomic hierarchies using TaxoNote

In this paper we describe TaxoNote Comparator, a tool for visualising and comparing multiple classification hierarchies. In order to align the hierarchies, the Comparator creates an integrated hierarchy containing all the taxa in the hierarchies to be compared, so that alignment of the hierarchies can be maintained. A table of assignments reports the taxonomic names that are common to all hierarchies and the differences between them, which facilitates structural comparisons between the hierarchies