Finite time collapse of N classical fields described by coupled nonlinear Schrodinger equations

We prove the finite-time collapse of a system of N classical fields, which are described by N coupled nonlinear Schrodinger equations. We derive the conditions under which all of the fields experiences this finite-time collapse. Finally, for two-dimensional systems, we derive constraints on the number of particles associated with each field that are necessary to prevent collapse.Comment: v2: corrected typo on equation

Modelling Backward Travelling Holes in Mixed Traffic Conditions Using an Agent Based Simulation

A spatial queue model in a multi-agent simulation framework is extended by introducing a more realistic behaviour, i.e. backward travelling holes. Space corresponding to a leaving vehicle is not available immediately on the upstream end of the link. Instead, the space travels backward with a constant speed. This space is named a ‘hole’. The resulting dynamics resemble Newell’s simplified kinematic wave model. Furthermore, fundamental diagrams from homogeneous and heterogeneous traffic simulations are presented. The sensitivity of the presented approach is tested with the help of flow density contours

Irrigation and Fertilization Practices for Seed Production from Established Stands of Side-oats Grama

The objectives of this study of grass seed production were to determine the response of an established stand of a warm-season grass to irrigation and fertilizer practices with regard to the specific practices needed to produce maximum quantity of adequate quality seed per acre. Side-oats grama was chosen for the study because of the availability of adapted varieties

Effects of Mowing Frequency on the Yield and Protein Content of Several Grasses Grown in Pure Stands

This paper presents results of a five-year experiment conducted at the Agricultural Experiment Station, Lincoln, Nebraska, on the adaptation, yield, and quality of several grasses subjected to different frequencies of harvest as a means of determining their forage value

Introduced Forage Grasses for Nebraska

This circular presents illustrations, descriptions and recommended usage of fourteen introduced cultivated grasses that are worthy of practical consideration in Nebraska. Most of them can easily be identified by comparing plant specimens with the illustrations and descriptions. This circular has been prepared for use by farmers, county agricultural agents, teachers and others who are interested in our most important grasses. Station Circular 59 contains information and illustrations of the more common native perennial grasses of Nebraska

Statistical Description of Acoustic Turbulence

We develop expressions for the nonlinear wave damping and frequency correction of a field of random, spatially homogeneous, acoustic waves. The implications for the nature of the equilibrium spectral energy distribution are discussedComment: PRE, Submitted. REVTeX, 16 pages, 3 figures (not included) PS Source of the paper with figures avalable at http://lvov.weizmann.ac.il/onlinelist.htm

The Impact of Organizational Sub Cultures on the Implementation of Component Based Development: A Case Study of an International Investment Bank

This paper presents a case study of the investment banking arm of a multinational banking corporation (Invebank) which is attempting to introduce Component-Based Development (CBD). Problems were apparent in this adoption because, while CBD requires extensive knowledge sharing and collaboration, sub-cultural differences between groups within Invebank meant that this proved difficult to enact. Thus, the paper considers the complexities of sub-cultural differences in firms and provides a salutary reminder that the implementation of so-called corporate-wide integrative ‘solutions’ such as Business Process Reengineering (BPR) and Enterprise Resource Planning (ERP) systems, as well as CBD, cannot, automatically, bear fruit in terms of firm performance. Further, the paper highlights the point that there is more to the issue of organizational sub-cultural differences than the oft-cited business-IT divide. The more simplistic entreaties to knowledge sharing and the nurture of collaborative cultures and consensus are also brought into question

Hopf algebras and characters of classical groups

Schur functions provide an integral basis of the ring of symmetric functions. It is shown that this ring has a natural Hopf algebra structure by identifying the appropriate product, coproduct, unit, counit and antipode, and their properties. Characters of covariant tensor irreducible representations of the classical groups GL(n), O(n) and Sp(n) are then expressed in terms of Schur functions, and the Hopf algebra is exploited in the determination of group-subgroup branching rules and the decomposition of tensor products. The analysis is carried out in terms of n-independent universal characters. The corresponding rings, CharGL, CharO and CharSp, of universal characters each have their own natural Hopf algebra structure. The appropriate product, coproduct, unit, counit and antipode are identified in each case.Comment: 9 pages. Uses jpconf.cls and jpconf11.clo. Presented by RCK at SSPCM'07, Myczkowce, Poland, Sept 200

Identification of the Cell Fate Gene Stalky in Dictyostelium

AbstractUsing insertional mutagenesis, we have isolated a “stalky” mutant in which cells destined to become spores end up as stalk cells. Similar mutants were previously observed after chemical mutagenesis, but the affected gene could not be isolated. Our mutant, like the previous ones, is in stkA. Its defect is cell-autonomous and not overcome by overexpressing cAMP-dependent protein kinase. stkA is strongly expressed in the prespore region of aggregates but not in the anterior prestalk zone. The mutant expresses normal levels of prespore-cell transcripts but fails to produce the spore transcript spiA. stkA encodes a predicted 99 kDa protein (STKA) with two putative C4 zinc fingers, one of which is a GATA-type finger, indicating that it may be a transcription factor. This conclusion is supported by localization of STKA in the nucleus