Modelling Water Trade in the Southern Murray-Darling Basin

Released in November 2004, the paper uses TERM-Water, a bottoms-up regional CGE model of the Australian economy, to examine the regional effects of expanding trade of irrigation water in the southern Murray- Darling Basin. The study finds that water trading dampens the impact of water allocation cuts on gross regional product (GRP). The benefits of introducing trading within irrigation districts are greater than the further benefits of expanding trade to between these regions. Permitting trade of seasonal allocations allows irrigators to reallocate water in reaction to climatic conditions and water availability - and it is this flexibility that enables GRP reductions to be minimised.southern murray-darling basin, CGE model, irrigation water, water allocation, water trade,

Radiation protection guidelines for space missions

NASA's current radiation protection guidelines date from 1970, when the career limit was set at 400 rem. Today, using the same approach, but with the current risk estimates, a considerably lower career limit would obtain. Also, there is considerably more information about the radiation environments to be experienced in different missions than previously. Since 1970 women have joined the ranks. For these and other reasons it was necessary to reexamine the radiation protection guidelines. This task was undertaken by the National Council on Radiation Protection and Measurements Scientific Committee 75 (NCRP SC 75). Below the magnetosphere the radiation environment varies with altitude and orbit inclination. In outer space missions galactic cosmic rays, with the small but important heavy ion component, determine the radiation environment. The new recommendations for career dose limits, based on lifetime excess risk of cancer mortality, take into account age at first exposure and sex. The career limits range from 100 rem (4.0Sv) for a 24 year old female to 400 rem for a 55 year old male compared to the previous single limit of 400 rem (4.0 Sv). The career limit for the lens of the eye was reduced from 600 to 400 rem (6.0 to 4.0 Sv.

Radioactive Iron Rain: Transporting 60^{60}Fe in Supernova Dust to the Ocean Floor

Several searches have found evidence of $^{60}$Fe deposition, presumably from a near-Earth supernova (SN), with concentrations that vary in different locations on Earth. This paper examines various influences on the path of interstellar dust carrying $^{60}$Fe from a SN through the heliosphere, with the aim of estimating the final global distribution on the ocean floor. We study the influences of magnetic fields, angle of arrival, wind and ocean cycling of SN material on the concentrations at different locations. We find that the passage of SN material through the mesosphere/lower thermosphere (MLT) is the greatest influence on the final global distribution, with ocean cycling causing lesser alteration as the SN material sinks to the ocean floor. SN distance estimates in previous works that assumed a uniform distribution are a good approximation. Including the effects on surface distributions, we estimate a distance of $46^{+10}_{-6}$ pc for a $8-10 \ M_{\odot}$ SN progenitor. This is consistent with a SN occurring within the Tuc-Hor stellar group $\sim$2.8 Myr ago with SN material arriving on Earth $\sim$2.2 Myr ago. We note that the SN dust retains directional information to within $1^{\circ}$ through its arrival in the inner Solar System, so that SN debris deposition on inert bodies such as the Moon will be anisotropic, and thus could in principle be used to infer directional information. In particular, we predict that existing lunar samples should show measurable $^{60}$Fe differences.Comment: 18 pages, 8 figures. Comments welcom

Astrophysical Shrapnel: Discriminating Among Near-Earth Stellar Explosion Sources of Live Radioactive Isotopes

We consider the production and deposition on Earth of isotopes with half-lives in the range 10$^{5}$ to 10$^{8}$ years that might provide signatures of nearby stellar explosions, extending previous analyses of Core-Collapse Supernovae (CCSNe) to include Electron-Capture Supernovae (ECSNe), Super-Asymptotic Giant Branch (SAGBs) stars, Thermonuclear/Type Ia Supernovae (TNSNe), and Kilonovae/Neutron Star Mergers (KNe). We revisit previous estimates of the $^{60}$Fe and $^{26}$Al signatures, and extend these estimates to include $^{244}$Pu and $^{53}$Mn. We discuss interpretations of the $^{60}$Fe signals in terrestrial and lunar reservoirs in terms of a nearby stellar ejection ~2.2 Myr ago, showing that (i) the $^{60}$Fe yield rules out the TNSN and KN interpretations, (ii) the $^{60}$Fe signals highly constrain a SAGB interpretation but do not completely them rule out, (iii) are consistent with a CCSN origin, and (iv) are highly compatible with an ECSN interpretation. Future measurements could resolve the radioisotope deposition over time, and we use the Sedov blast wave solution to illustrate possible time-resolved profiles. Measuring such profiles would independently probe the blast properties including distance, and would provide additional constraints the nature of the explosion.Comment: 38 pages, 6 figures. Comments welcom

Foot-operated cell-counter

Cell-counter for cell indices consists of a footboard with four pressure sensitive switches and an enclosure for the components and circuitry. This device increases the operators efficiency by reducing the number of required hand movements

QED in strong, finite-flux magnetic fields

Lower bounds are placed on the fermionic determinants of Euclidean quantum electrodynamics in two and four dimensions in the presence of a smooth, finite-flux, static, unidirectional magnetic field $B(r) =(0,0,B(r))$, where $B(r) \geq 0$ or $B(r) \leq 0$, and $r$ is a point in the xy-plane.Comment: 10 pages, postscript (in uuencoded compressed tar file

Near-IR photodissociation of peroxy acetyl nitrate

Measurements of the C-H overtone transition strengths combined with estimates of the photodissociation cross sections for these transitions suggest that near-IR photodissociation of peroxy acetyl nitrate (PAN) is less significant (Jnear−IR ~3×10^−8 s^−1 at noon) in the lower atmosphere than competing sinks resulting from unimolecular decomposition and ultraviolet photolysis. This is in contrast to the photochemical behavior of a related peroxy nitrate, pernitric acid (PNA), that undergoes rapid near-IR photolysis in the atmosphere with Jnear−IR ~10^−5 s^−1 at noon (Roehl et al., 2002). This difference is attributed to the larger binding energy and larger number of vibrational degrees of 10 freedom in PAN, which make 4[Greek nu]CH the lowest overtone excitation with a high photodissociation yield (as opposed to 2[Greek nu]OH in PNA)

Learned Helplessness: A Case Study of a Middle School Student

This is the publisher's version, also found at http://ehis.ebscohost.com/ehost/detail?vid=4&sid=18c07398-402e-4572-aa35-4d1deeeff1be%40sessionmgr15&hid=2&bdata=JnNpdGU9ZWhvc3QtbGl2ZQ%3d%3d#db=s3h&AN=2075200

Nitrous Oxide Emissions and Carbon Sequestration in Turfgrass: Effects of Irrigation and Nitrogen Fertilization (Year 1)

In this study, annual nitrous oxide (N2O) emissions were greatest in urea and least in untreated (no N) among treatments. Differences were negligible due to irrigation treatment. Irrigation levels may be decreased further in the final year to induce slight stress on the low irrigation treatment. All fertilizer treatments maintained acceptable quality, however the controlled-release fertilizer resulted in more consistent visual quality ratings compared to urea and untreated. Urea fertilizer had higher peak fluxes after fertilization and overall annual emissions than polymer-coated N-fertilizer. Thus, controlled released N fertilizers, such as polymer-coated urea, in turfgrass systems could potentially help mitigate N2O emissions