Design of Minimum Energy Culverts

After model testing, a number of Minimum Energy structures have been built and have been subjected to flows of some magnitude during the reasonably wet summer of 1970-1971. It is proposed to give the detail design of some of these structures and a report of their observed behaviour. As the design procedure is not restricted to road structures, the behaviour of other structures is also reported as their performance is essentially linked to the validity of the basic concept. It would appear that the concept of constant total energy and compatible specific energy is valid within the limits required for practical design. That the minimum energy condition can be used to provide economic structures for a wide variety of purposes. Although the concept leads to, quite different forms which for full development may require some variation of traditional construction requirements, it has been shown that with present methods considerable savings are nevertheless possible. The concept offers practical solutions to ,previously unsolved problems. The design techniques suggested to make use of this concept allow for much more detailed analysis than is otherwise possible. Essentially the designs minimize the r3ndom turbulence normally associated with Civil Engineering structures. Although the design determines wher e energy is .bes t dissipated, it is still not possible to control "lith any accuracy the rate of dissipation. The limits to which the techniques can be successfully used are not yet defined, but the operation full size does appear to be more favourable than on a model

Tolerance of Pseudomonas aeruginosa in in vitro biofilms to high level peracetic acid disinfection

Biofilm has been suggested as a cause of disinfection failures in flexible endoscopes where no lapses in the decontamination procedure can be identified. To test this theory, the activity of peracetic acid (PAA), one of the commonly used disinfectants in the reprocessing of flexible endoscopes, was evaluated against both planktonic and sessile communities of Pseudomonas aeruginosa. To investigate the ability of P. aeruginosa biofilm to survive high level PAA disinfection. The susceptibility of planktonic cells of P. aeruginosa and biofilms 24, 48, 96 and 192 h old to PAA was evaluated by estimating their viability using resazurin viability and plate count methods. The biomass of the P. aeruginosa biofilms was also quantified using crystal violet assay. Planktonic cells of P. aeruginosa were treated with 5 - 30 ppm concentration of PAA in the presence of 3.0 g/L of Bovine serum albumin (BSA) for 5 min. Biofilms of P. aeruginosa were also treated with various PAA concentrations (100 - 3000 ppm) for 5 min. Planktonic cells of P. aeruginosa were eradicated by 20 ppm of PAA, whereas biofilms showed an age dependent tolerance to PAA, and 96 h old biofilm was only eradicated at PAA concentration of 2500 ppm. 96 h old P. aeruginosa biofilm survives 5 min treatment with 2000 ppm of PAA, which is the working concentration used in some endoscope washer disinfectors. This implies that disinfection failure of flexible endoscopes could occur when biofilms are allowed to build up in the lumens of endoscopes

Mineralogical study of angrite Asuka-881371: Its possible relation to angrite LEW87051

Antarctic angrites LEW87051 (LEW) and Asuka-881371 (Asuka) have distinctive textural and mineralogical affinities. LEW is porphyritic in texture with zoned olivines (∿0.5mm) widely distributed in a fine-grained groundmass. Several olivines are known to contain Mg, Cr-rich cores which are out of equilibrium with groundmass olivines and are considered to be xenocrysts. Asuka is ophitic in texture with large olivine xenocrysts (some larger than 2mm across) included in a groundmass. These olivines reach up to Fo_, and are as rich in Cr and poor in Ca as LEW olivine cores. Despite these similarities, the variability of the olivine compositions differs between the two. Olivine cores of LEW are almost homogeneous in composition from one grain to another, while the large olivines in Asuka show significant grain-to-grain variation. Each large olivine xenocryst in Asuka is nearly homogeneous except for the remarkably zoned edge indicating reaction with the surrounding melt. Some small olivine xenocrysts in Asuka (∿0.5mm across) have zoning profiles similar to the two-stage zoning profile observed in LEW olivines. However they are interpreted to have the same origin as the other xenocrysts, with the difference being in the zoning profiles, caused by the effect of off-center cuts through the grains. We propose that the difference between LEW and Asuka olivine xenocrysts is produced by differing degrees of melting. The cores of LEW olivines are more clearly zoned than Asuka xenocrysts possibly due to a higher degree of atomic diffusion in LEW olivine. We previously calculated the cooling rate of LEW olivines and estimated that their burial depth was shallower than 2m. Our model for the formation of the LEW and Asuka angrites is as follows. Homogeneous olivine crystals with extensive chemical variation from one crystal to another were somehow incorporated into a melt and reheated. In the case of LEW, almost all the olivines except for the extremely Mg-rich ones were totally melted, while in Asuka even the Fo_ olivines did not melt. After the melting stage, the groundmass of both LEW and Asuka crystallized. Asuka groundmass minerals have ∿2x larger grain sizes than LEW. This difference will reflect differences in burial depth. LEW crystallized near the surface (∿2m) where the degree of melting was larger, whereas Asuka crystallized at a deeper burial depth and yet experienced less heating and melting. More intense melting at a shallower depth suggests an external heat source, possibly impact melting

Trace element distributions in Yamato-793605, a chip off the "martian lherzolite" block

In situ ion microprobe analyses of various phases in Yamato-793605 (Y79) confirm that it is very similar to the other two lherzolitic shergottites, ALHA77005 and LEW88516. Differences in absolute REE abundances between bulk samples of these meteorites can be largely accounted for by sample heterogeneity. The three lherzolites were formed by essentially identical processes and they may even have originated from the same lithological unit on Mars. Preservation of major element zonation in olivines of Y79 indicates that it is less equilibrated than the other lherzolitic shergottites, and may have crystallized at shallower depth. The parent magmas of lherzolitic shergottites, like those of other shergottites, were derived by partial melting of a partly depleted martian mantle

Studies of Magmatic Inclusions in the Basaltic Martian Meteorites Shergotty, Zagami, EETA 79001 and QUE 94201

Currently there are 12 meteorites thought by planetary scientists to be martian samples, delivered to the Earth after violent impacts on that planet's surface. Of these 12 specimens, 4 are basaltic: Shergotty, Zagami, EETA 79001 and QUE 94201. Basalts are particularly important rocks to planetary geologists- they are the most common rocks found on the surfaces of the terrestrial planets, representing volcanic activity of their parent worlds. In addition, because they are generated by partial melting of the mantle and/or lower crust, they can serve as guide posts to the composition and internal processes of a planet. Consequently these four meteorites can serve as 'ground-truth' representatives of the predominant volcanic surface rocks of Mars, and offer researchers a glimpse of the magmatic history of that planet. Unfortunately, unraveling the parentage of a basaltic rock is not always straightforward. While many basalts are simple, unaltered partial melts of the mantle, others have undergone secondary processes which change the original parental chemistry, such as assimilation of other crustal rocks, mixing with other magmas, accumulation, re-equilibration between mineral species after crystallization, loss of late-stage magmatic fluids and alteration by metamorphic or metasomatic processes. Fortunately, magmatic inclusions can trap the evolving magmatic liquid, isolating it from many of these secondary processes and offering a direct look at the magma during different stages of development. These inclusions form when major or minor phases grow skeletally, surrounding small amounts of the parental magma within pockets in the growing crystal. The inclusion as a whole (usually consisting of glass with enclosed crystals) continues to represent the composition of the parental magma at the time the melt pocket closed, even when the rock as a whole evolves under changing conditions. The four basaltic martian meteorites contain several distinct generations of melt inclusions; those found within early-forming pigeonite, intermediate and late-forming Ti, Fe-oxides and sulfides, and intermediate to late-forming phosphates. In this summer' s study we have made a detailed study of all of the various forms of inclusions found within the 4 basaltic martian meteorites listed above. Glasses and minerals within the inclusions were analyzed using the Camera SX-100 Electron Microprobe in Building 31. The mineralogy and textural context of the inclusions will then be used to explore the crystallization history of these specimens, and to investigate any differences in crystallization history or parental magma compositions between these rocks. In this manner, the magmatic inclusions provide a road map backwards toward the 'parental' compositions for the basaltic martian meteorites and provide significant insight into the igneous processes found within the crust of Mars

Rare Earth Element Partition Coefficients from Enstatite/Melt Synthesis Experiments

Enstatite (En(80)Fs(19)Wo(01)) was synthesized from a hypersthene normative basaltic melt doped at the same time with La, Ce, Nd, Sm, Eu, Dy, Er, Yb and Lu. The rare earth element concentrations were measured in both the basaltic glass and the enstatite. Rare earth element concentrations in the glass were determined by electron microprobe analysis with uncertainties less than two percent relative. Rare earth element concentrations in enstatite were determined by secondary ion mass spectrometry with uncertainties less than five percent relative. The resulting rare earth element partition signature for enstatite is similar to previous calculated and composite low-Ca pigeonite signatures, but is better defined and differs in several details. The partition coefficients are consistent with crystal structural constraints

Workshop on Mars Sample Return Science

Martian magnetic history; quarantine issues; surface modifying processes; climate and atmosphere; sampling sites and strategies; and life sciences were among the topics discussed

Experiences in deploying metadata analysis tools for institutional repositories

Current institutional repository software provides few tools to help metadata librarians understand and analyze their collections. In this article, we compare and contrast metadata analysis tools that were developed simultaneously, but independently, at two New Zealand institutions during a period of national investment in research repositories: the Metadata Analysis Tool (MAT) at The University of Waikato, and the Kiwi Research Information Service (KRIS) at the National Library of New Zealand. The tools have many similarities: they are convenient, online, on-demand services that harvest metadata using OAI-PMH; they were developed in response to feedback from repository administrators; and they both help pinpoint specific metadata errors as well as generating summary statistics. They also have significant differences: one is a dedicated tool wheres the other is part of a wider access tool; one gives a holistic view of the metadata whereas the other looks for specific problems; one seeks patterns in the data values whereas the other checks that those values conform to metadata standards. Both tools work in a complementary manner to existing Web-based administration tools. We have observed that discovery and correction of metadata errors can be quickly achieved by switching Web browser views from the analysis tool to the repository interface, and back. We summarize the findings from both tools' deployment into a checklist of requirements for metadata analysis tools

DNA methylation as a potential mediator of environmental risks in the development of childhood acute lymphoblastic leukemia

5-year survival rate for childhood acute lymphoblastic leukemia (ALL) has risen to approximately 90%, yet the causal disease pathway is still poorly understood. Evidence suggests multiple 'hits' are required for disease progression; an initial genetic abnormality followed by additional secondary 'hits'. It is plausible that environmental influences may trigger these secondary hits, and with the peak incidence of diagnosis between 2 and 5 years of age, early life exposures are likely to be key. DNA methylation can be modified by many environmental exposures and is dramatically altered in cancers, including childhood ALL. Here we explore the potential that DNA methylation may be involved in the causal pathway toward disease by acting as a mediator between established environmental factors and childhood ALL development