Chemical control of Poa trivialis on New Zealand racetracks : a thesis presented in partial fulfilment of the requirements for the degree of Master of Applied Science at Massey University

Poa trivialis is a perennial grass weed commonly found in perennial ryegrass (Lolium perenne) racetrack swards throughout New Zealand. Its presence is undesirable as it does not tolerate high wear and is susceptible to dying out over the summer. Two pot trials at Massey University and one field trial carried out at the Awapuni racecourse were conducted during winter and spring 1995 to test the relative susceptibility of Poa trivialis and perennial ryegrass to a wide range of herbicides. A bioassay was also conducted to determine whether herbicide residues from the field trial could affect the germination of perennial ryegrass seed sown soon after treatment. Results showed that none of the chemicals at their chosen respective rates could completely remove Poa trivialis from a racetrack sward in the spring without some damage being caused to perennial ryegrass. Propyzamide and fenoxaprop at rates of 0.2 and 0.15 kg/ha respectively showed the most potential of the chemicals, severely damaging Poa trivialis (causing 50 to 75% reductions) with no adverse effect on perennial ryegrass 8 weeks after spraying. Propyzamide can also provide some control of Poa annua. Fenoxaprop was not improved by increasing the application rate or adding an oil. The performance of fenoxaprop was substantially reduced when applied with either MCPA or a picloram/triclopyr mix. Dalapon and asulam showed good potential to control Poa trivialis but at the high rates tested caused variable or harmful effects to perennial ryegrass. Ethofumesate and chlorpropham applied at rates of 2.0 and 2.5 kg/ha respectively gave inadequate control of Poa trivialis. None of the above herbicides, when used in the field trial resulted in residues which reduced the germination of perennial ryegrass seed sown 3 weeks after spraying. Herbicides tested in the pot trials which showed poor control of Poa trivialis were atrazine, dicamba, isoproturon/diflufenican, linuron, mecoprop, methabenzthiazuron, metsulfuron, pendimethalin, prometryne, thifensulfuron-methyl, triclopyr, and trinexapac-ethyl. Diuron applied at 2.6 kg/ha provided good control of Poa trivialis but caused significant damage to perennial ryegrass. It is concluded that an integrated management approach that incorporates both cultural and chemical techniques will be required to control Poa trivialis on New Zealand racetracks. Future trial work should be carried out on propyzamide applied at rates of 0.2-0.3 kg/ha in autumn to establish the most appropriate time of year to apply this herbicide

Mechanism State Matrices for Spatial Reconfigurable Mechanisms

This paper improves augmented mechanism state matrices by replacing joint code with screw system notation. The proposed substitution allows for a more specific description of the joints in the mechanism and the capability to describe both spatial and planar mechanisms. Examples are provided which elucidate the proposed approach

Wavefunction Collapse and Random Walk

Wavefunction collapse models modify Schrodinger's equation so that it describes the rapid evolution of a superposition of macroscopically distinguishable states to one of them. This provides a phenomenological basis for a physical resolution to the so-called "measurement problem." Such models have experimentally testable differences from standard quantum theory. The most well developed such model at present is the Continuous Spontaneous Localization (CSL) model in which a fluctuating classical field interacts with particles to cause collapse. One "side effect" of this interaction is that the field imparts momentum to particles, causing a small blob of matter to undergo random walk. Here we explore this in order to supply predictions which could be experimentally tested. We examine the translational diffusion of a sphere and a disc, and the rotational diffusion of a disc, according to CSL. For example, we find that a disc of radius 2 cdot 10^{-5} cm and thickness 0.5 cdot 10^{-5} cm diffuses through 2 pi rad in about 70sec (this assumes the "standard" CSL parameter values). The comparable rms diffusion of standard quantum theory is smaller than this by a factor 10^-3. At the reported pressure of < 5 cdot10^{-17} Torr, achieved at 4.2^{circ} K, the mean time between air molecule collisions with the disc is approximately 45min (and the diffusion caused by photon collisons is utterly negligible). This is ample time for observation of the putative CSL diffusion over a wide range of parameters. This encourages consideration of how such an experiment may actually be performed, and the paper closes with some thoughts on this subjectComment: 27 pages, 2 figure

Dimensions of web site credibility and their relation to active trust and behavioural impact

This paper discusses two trends that threaten to undermine the effectiveness of online social marketing interventions: growing mistrust and competition. As a solution, this paper examines the relationships between Web site credibility, target audiences’ active trust and behaviour. Using structural equation modelling to evaluate two credibility models, this study concludes that Web site credibility is best considered a three-dimensional construct composed of expertise, trustworthiness and visual appeal, and that trust plays a partial mediating role between Web site credibility and behavioural impacts. The paper examines theoretical implications of conceptualizing Web sites according to a human credibility model, and factoring trust into Internet-based behavioural change interventions. Practical guidelines suggest ways to address these findings when planning online social marketing interventions

A new database program installed at the SUERC radiocarbon laboratory

The SUERC Radiocarbon Dating Laboratory has recently replaced its spreadsheet-based record keeping with a new database program, custom designed to help laboratory staff manage the high throughput of nearly 5000 cathodes in the past year. The system can accept data from a variety of sources in addition to manual entry; experimental results can be uploaded from spreadsheets, while integration with graphitisation lines means that graphite yields are automatically recorded. The system is able to pass radiocarbon results directly to OxCal 4 for calibration, with the resulting plots incorporated into the dating certificates issued to submitters. There are also benefits to submitters, with electronic sample submission both eliminating transcription errors and speeding up the logging-in process which keeps turnaround times down. For bone samples, data on collagen yields are now stored electronically and are more readily obtainable from the laboratory. The new SUERC Radiocarbon Dating Laboratory database will make a significant contribution to maintaining the high quality of results produced by the laboratory, aiding staff in tracking sample progress and monitoring quality assurance (QA) samples going through the laboratory, eliminating transcription errors and making communication easier between laboratory staff and sample submitters