Power law burst and inter-burst interval distributions in the solar wind: turbulence or dissipative SOC ?

We calculate for the first time the probability density functions (PDFs) P of burst energy e, duration T and inter-burst interval tau for a known turbulent system in nature. Bursts in the earth-sun component of the Poynting flux at 1 AU in the solar wind were measured using the MFI and SWE experiments on the NASA WIND spacecraft. We find P(e) and P(T) to be power laws, consistent with self-organised criticality (SOC). We find also a power law form for P(tau) that distinguishes this turbulent cascade from the exponential P(tau) of ideal SOC, but not from some other SOC-like sandpile models. We discuss the implications for the relation between SOC and turbulence.Comment: 3 pages, 1 figure. Submitted to PRL on 25th February 2000. Revised version re-submitted on 9th May 2000. Second revised version submitted Phys. Rev. E on 26th June, 200

A simplex-like search method for bi-objective optimization

We describe a new algorithm for bi-objective optimization, similar to the Nelder Mead simplex algorithm, widely used for single objective optimization. For diferentiable bi-objective functions on a continuous search space, internal Pareto optima occur where the two gradient vectors point in opposite directions. So such optima may be located by minimizing the cosine of the angle between these vectors. This requires a complex rather than a simplex, so we term the technique the \cosine seeking complex". An extra beneft of this approach is that a successful search identifes the direction of the effcient curve of Pareto points, expediting further searches. Results are presented for some standard test functions. The method presented is quite complicated and space considerations here preclude complete details. We hope to publish a fuller description in another place

Copper and zinc nutrition experimental results.

Long term copper trial - Newdegate research station, 66N14. Copper, zinc and sulphur residual with DAP for wheat, 78WH66. Copper and zinc residual with dap 78Mo36. Zinc residual with high analysis n.p. fertiliser for wheat 80no31. Zinc residual with high analysis n.p. fertiliser for wheat 79me22, 79me23. Zinc residual with high analysis n.p. fertiliser for wheat 82mo8. Zinc, copper and sulphur residual with DAP, 781G27. Methods of copper application on new land, 85JE48. Evaluation of copper ore 85LG47. Zinc by nitrogen interaction, 85LG28. Zinc residual with DAP, 85LG29. Copper sulphate, copper chelate and copper oxychloride effectiveness for wheat, 85LG26. Zinc sulphate, zinc chelate sprays on wheat, 85LG

Trace element nutrition

South Perth Long term copper trial - Newdegate Research Station – 66N14. Copper, zinc & sulphur residual with DAP for wheat – 78WH66. Copper and zinc residual with DAP – 78MO36. Zinc residual with high analysis N.P. fertilizer for wheat – 79ME22, 79ME23, 80MO8, 80NO31. Cereal responses to zinc Copper and nitrogen interactions on wheat varieties – 83GE2, 83WH1. Barley responses to drilled trace elements – 83BR4, 83BR5. Manganese on wheat – 82NO8. ESPERANCE Zinc residual with high analysis N.P. fertilizer for wheat – 83ES35. Methods of copper application on new land – 83LG6. Copper spray and nitrogen rate applications to wheat supplied with super, copper, zinc and molybdenum no. 1 – 83LG4. Copper sprays on wheat – 84LG3. Zinc sulphate, zinc chelate sprays on wheat – 84LG4. Nitrogen and Hoegrass@ on zinc nutrition of wheat grown on heavy land – 84LG30. Hoegrass@ on zinc nutrition of wheat varieties – 84LGX

Fox Squirrels Cause Power Outages: An Urban Wildlife Problem

In urban areas, power outages are caused each year by fox squirrels (Sciurus niger) that use electrical power equipment as travel lanes, rest sites, or for other activities. When a squirrel crosses a live bare wire on a transformer, the result is a blown fuse and electrocution of the squirrel. Power company outage reports were examined to determine when and where squirrel-caused outages occurred. Sixteen field sites in Lincoln were selected for study. Eight sites encircled transformers with ≥4 squirrel-caused outages, 1980-1985, and eight were adjacent control sites with no such outages. Squirrel behavior in relation to power equipment was observed and habitat variables were measured at all sites. Additional data on vegetation within 2 m of the power equipment were collected at 22 sites in Omaha. Eleven Omaha sites were at transformers that had ≥3 squirrel-caused outages (1985-1986) and 11 were at adjacent control sites. Results indicate that problem sites had more squirrels than control sites. Numbers of leaf nests were significantly greater in problem sites (P \u3c 0.05). In addition, squirrels were observed almost twice as many minutes in problem sites, and time-area counts indicated increased numbers of squirrels in problem sites. Mean basal area of mulberries within 2 m of all power equipment and within 2 m of the power pole was 2.5 or 15 times greater, respectively, in problem sites than in control sites. Results indicate that barriers and habitat management may be potential control techniques. Results of this study provide a greater understanding of squirrel biology in urban environments and may yield greater predictability and control of squirrel-caused power outages

A novel metric for coronal MHD models

[1] In the interest of quantitatively assessing the capabilities of coronal MHD models, we have developed a metric that compares the structures of the white light corona observed with SOHO LASCO C2 to model predictions. The MAS model is compared to C2 observations from two Carrington rotations during solar cycle 23, CR1913 and CR1984, which were near the minimum and maximum of solar activity, respectively, for three radial heights, 2.5 R⊙, 3.0 R⊙, and 4.5 R⊙. In addition to simulated polarization brightness images, we create a synthetic image based on the field topology along the line of sight in the model. This open-closed brightness is also compared to LASCO C2 after renormalization. In general, the model\u27s magnetic structure is a closer match to observed coronal structures than the model\u27s density structure. This is expected from the simplified energy equations used in current global corona MHD models

Development and Preliminary Application of Mathematical Models to the Weber Basin

The adoption of stream standards, whether for direct application or for the establishment of realistic effluent standards, creates a need to predict the impact of pollution loads on river water quality during critical flow periods or as the result of future user demands. Because of the complexity of aquatic systems, mathematical models are an excellent medium for bringing together the state-of-the-art knowledge from a variety of disciplines into a form which can be readily applied to practical problems. Applying a mathematical model to a river system has the added advantage of providing a structure for the systematic consideration of the many diverse aspects of water quality phenomena. This report describes the development of a river simulation model (QUAL-U) for predicting water quality and its preliminary application to the Weber River drainage basin in northeastern Utah. The model involves the numerical solution of a set of differential equations representing the aquatic system under steady state conditions. The development and use of a second model which provides the flow boundary conditions for the first model is also described. This model is a simple interactive procedure for obtaining flows at specified locations on the river system given the measured flows at other locations and typical flow ranges of headwater, diversions, surface and subsurface lateral inflows, and point loads. Previous river water quality models are reviewed and the structure of QUAL-U is presented. The economic and physical characteristics of the study area are described and the Weber River system is represented by subbasins, reaches, and computational units. Model calibration was based on water quality data collected at over eighty sampling locations in the study area during a four day period in September, 1973. Each of the sampling points was subsequently surveyed to obtain representative hydraulic characteristics for each reach of the river system. Coefficients for the mathematical equations representing hydraulic characteristics and chemical and biological reactions were estimated and adjusted during the model calibration procedure until model responses satisfactorily resembled the observed data. Results for the calibration period and also for studies involving critical low flow conditions are described and model limitations are considered. The work on which this report is based was performed for the State of Utah, Department of Social Services, Division of Health as part of a Waste Load Allocation Study on the Weber River. The scope of this project provided only for supplying the calibrated model to the client and does not include predictive runs or interpretation of management alternatives

Boron toxicity in barley.

Field trials. Intraspecific variation in Barley to Boron toxicity, 85Me55, 85SG29, 85SG33. Glasshouse experiments. Sampling techniques for Boron toxicity in Barley, 85GL2. Cartwright rating system, leaf rating system

15 years of VLBI observations of two compact radio sources in Messier 82

We present the results of a second epoch of 18cm global Very Long-Baseline Interferometry (VLBI) observations, taken on 23 February 2001, of the central kiloparsec of the nearby starburst galaxy Messier 82. These observations further investigate the structural and flux evolution of the most compact radio sources in the central region of M82. The two most compact radio objects in M82 have been investigated (41.95+575 and 43.31+592). Using this recent epoch of data in comparison with our previous global VLBI observations and two earlier epochs of European VLBI Network observations we measure expansion velocities in the range of 1500-2000km/s for 41.95+575, and 9000-11000km/s for 43.31+592 using various independent methods. In each case the measured remnant expansion velocities are significantly larger than the canonical expansion velocity (500km/s) of supernova remnants within M82 predicted from theoretical models. In this paper we discuss the implications of these measured expansion velocities with respect to the high density environment that the SNR are expected to reside in within the centre of the M82 starburst.Comment: Accepted for publication in MNRAS, 9 pages, 8 figure

Implicit reconstructions of thin leaf surfaces from large, noisy point clouds

Thin surfaces, such as the leaves of a plant, pose a significant challenge for implicit surface reconstruction techniques, which typically assume a closed, orientable surface. We show that by approximately interpolating a point cloud of the surface (augmented with off-surface points) and restricting the evaluation of the interpolant to a tight domain around the point cloud, we need only require an orientable surface for the reconstruction. We use polyharmonic smoothing splines to fit approximate interpolants to noisy data, and a partition of unity method with an octree-like strategy for choosing subdomains. This method enables us to interpolate an N-point dataset in O(N) operations. We present results for point clouds of capsicum and tomato plants, scanned with a handheld device. An important outcome of the work is that sufficiently smooth leaf surfaces are generated that are amenable for droplet spreading simulations