Development of biaxial test fixture includes cryogenic application

Test fixture has the capability of producing biaxial stress fields in test specimens to the point of failure. It determines biaxial stress by dividing the applied load by the net cross section. With modification it can evaluate materials, design concepts, and production hardware at cryogenic temperatures

The economics of rabbit control in Central Otago: A preliminary analysis

With contributions by J.M. Williams, J. Bell and T.M. Broad, Agricultural Research Division, Ministry of Agriculture and Fisheries. Prepared under contract for Agricultural Research Division Ministry of Agriculture and Fisheries, WellingtonThis paper reports a preliminary examination of the economic efficiency and equity implications of recent rabbit control policies and programmes. The Alexandra Pest Destruction Board in Central Otago was used as a case study. Public and private expenditure data on rabbit control were collected and analysed for the period 1974-75 through 1981-82. Control programme benefits were estimated using data obtained in a survey of runholders and from historical production records. Programme costs were developed from actual expenditure data on control operations and administration based on Board records. While the estimated benefits are much less precise in comparison to programme costs, the results of the cost-benefit analysis suggest that significant cost savings can be achieved in meeting the stated objectives of current pest management policies. In particular, the level of annual expenditure in recent years on those lands which can be regarded as good natural habitat for the feral rabbit does not appear to be warranted, since such land types have an inherently low productive capacity and could not sustain the present level of control input on a 'user pays' basis. Although certain public benefits (e.g., land and water conservation) were not estimated, such benefits would have to be quite large to justify recent levels of annual taxpayer input into APDB control operations. The incidence of programme costs under present policy shows that most of the burden is borne by the tax-paying public. The report concludes with some suggestions to appraise these implications more accurately for regional and national public policy

An experimental evaluation of a loop versus a reference design for two-channel microarrays

Motivation: Despite theoretical arguments that socalled "loop designs" of two-channel DNA microarray experiments are more efficient, biologists keep on using "reference designs". We describe two sets of microarray experiments with RNA from two different biological systems (TPA-stimulated mammalian cells and Streptomyces coelicor). In each case, both a loop and a reference design were performed using the same RNA preparations with the aim to study their relative efficiency. Results: The results of these experiments show that (1) the loop design attains a much higher precision than the reference design, (2) multiplicative spot effects are a large source of variability, and if they are not accounted for in the mathematical model, for example by taking log-ratios or including spot-effects, then the model will perform poorly. The first result is reinforced by a simulation study. Practical recommendations are given on how simple loop designs can be extended to more realistic experimental designs and how standard statistical methods allow the experimentalist to use and interpret the results from loop designs in practice

Ozone trends estimated from Umkehr observations made at Edmonton, Alberta, Canada

A Brewer Ozone Spectrophotometer has been in service at the Canadian ozone monitoring station at Stony Plain (53.55 deg N, 114.10 deg W), near Edmonton, Alberta, since 1984. During that time, the instrument has been operated in a fully automated mode that includes the collection of morning and evening Umkehr observations. Some 197 Umkehr observations have been analyzed to make an estimate of the temporal trend in ozone amount at high altitude over the station during the last 8 years. This work has shown that at 40 km the trend in the ozone concentration has been observed to be 0.14 plus or minus 0.10 percent per year

Kerr-Schild Symmetries

We study continuous groups of generalized Kerr-Schild transformations and the vector fields that generate them in any n-dimensional manifold with a Lorentzian metric. We prove that all these vector fields can be intrinsically characterized and that they constitute a Lie algebra if the null deformation direction is fixed. The properties of these Lie algebras are briefly analyzed and we show that they are generically finite-dimensional but that they may have infinite dimension in some relevant situations. The most general vector fields of the above type are explicitly constructed for the following cases: any two-dimensional metric, the general spherically symmetric metric and deformation direction, and the flat metric with parallel or cylindrical deformation directions.Comment: 15 pages, no figures, LaTe

Five New Millisecond Pulsars From a Radio Survey of 14 Unidentified Fermi-LAT Gamma-ray Sources

We have discovered five millisecond pulsars (MSPs) in a survey of 14 unidentified Fermi-LAT sources in the southern sky using the Parkes radio telescope. PSRs J0101-6422, J1514-4946, and J1902-5105 reside in binaries, while PSRs J1658-5324 and J1747-4036 are isolated. Using an ephemeris derived from timing observations of PSR J0101-6422 (P =2.57 ms, DM=12 pc cm-3), we have detected {\gamma}-ray pulsations and measured its proper motion. Its {\gamma}-ray spectrum (a power law of {\Gamma} = 0.9 with a cutoff at 1.6 GeV) and efficiency are typical of other MSPs, but its radio and {\gamma}-ray light curves challenge simple geometric models of emission. The high success rate of this survey-enabled by selecting {\gamma}-ray sources based on their detailed spectral characteristics-and other similarly successful searches indicate that a substantial fraction of the local population of MSPs may soon be known.Comment: 6 pages, 3 figures, 2 tables, accepted by ApJ