Developing simplified synergistic relationships to model topsoil erosion and crop yield

Non-Peer ReviewedTopsoil is highly enriched with organic matter, which provides a valuable source of plant nutrients as well as a favorable rooting environment. Over time, erosion processes selectively remove the organic matter-rich fine fraction which causes a measurable reduction in soil productivity. Assessments of past erosion are of little value in predicting future losses in productivity since the synergistic lowering of soil organic matter through lower residue inputs is not considered. Dynamic computer models, which simulate the plant/soil system, can project the long run future costs of soil erosion on crop yield. A simplified erosion-crop yield model was developed by first defining the most important soil productivity variables, then quantifying the effect of erosion on each variable. The model predicted a declining trend in grain yields similar to that observed on soil scalping experiments

Simulated Productivity Lost by Erosion (SimPLE): model development, validation, and use

Non-Peer ReviewedProductivity lost due to soil erosion can be estimated by existing computer simulation models such as EPIC, NTRM and CENTURY. However, these models require extensive input data and, to date, have had limited success in simulating Western Canadian conditions. The objective of this study was to develop a simple spring wheat model which captured the essential relationships between topsoil erosion and productivity loss in Chemozemic soils. Key relationships in our model describe: (i) how plants create yield from water, N, and P; (ii) how the soil provides these nutrients, and (iii) how erosion impacts on the supply of each nutrient. These relationships were logically connected using the Stella® II modeling environment. Agreement was highly significant (r = 0.55***) between predicted and observed grain yields over 75 site years at Indian Head, Saskatchewan. Also, grain yields from scalped Chemozemic soils in Alberta were closely simulated (r = 0.86****) by SimPLE. Fifty representative soil profiles from the Brown, Dark Brown and Black soil zones were eroded in SimPLE to numerically describe the production lost under wet, normal, and dry scenarios, with and without optimum fertilizer. Yield loss, as a percentage of non-eroded yield, increased with increasing soil erosion following a trend very similar to that reported in field studies. SimPLE is flexible and can be used for analysis of "what if' management scenarios or calculating soil loss tolerance (T) values

Estimating the cost-effectiveness of brief interventions for heavy drinking in primary health care across Europe

Background Screening and Brief Interventions for alcohol are an effective public health measure to tackle alcohol-related harm, however relatively few countries across the European Union (EU) have implemented them widely. This may be due to a lack of understanding of the specific financial implications of such policies within each country. Methods A novel ‘meta-modelling’ approach was developed based on previous SBI cost-effectiveness models for four EU countries. Data was collected on the key factors which drive cost-effectiveness for all 28 EU countries (mean per capita alcohol consumption, proportion of the population to be screened over a 10-year SBI programme; per capita alcohol-attributable mortality; per capita alcoholattributable morbidity; mean cost of an alcohol-related hospitalisation and mean SBI-delivery staff cost). Regression analysis was used to fit two meta-models estimating net programme costs and quality-adjusted life-years (QALYs) gained, to calculate cost-effectiveness estimates specific to each EU country. Results Costs are dependent upon the proportion of the population covered by the screening programme, the country-specific per capita mortality and morbidity rate and the country-specific costs of GP care and hospitalisation. QALYs depend on the proportion of the population screened and per capita alcohol consumption. Despite large inter-country variability in factor values, SBI programmes are likely to be cost-effective in 24 out of 28 EU countries and cost-saving in about 50% of countries. Conclusion Implementing national programmes of SBI in primary health care would be a cost-effective means of reducing alcohol-attributable morbidity and deaths in almost all countries of the EU

Electronic Structure of Transition-Metal Dicyanamides Me[N(CN)2_2]2_2 (Me = Mn, Fe, Co, Ni, Cu)

The electronic structure of Me[N(CN)$_2$]$_2$ (Me=Mn, Fe, Co, Ni, Cu) molecular magnets has been investigated using x-ray emission spectroscopy (XES) and x-ray photoelectron spectroscopy (XPS) as well as theoretical density-functional-based methods. Both theory and experiments show that the top of the valence band is dominated by Me 3d bands, while a strong hybridization between C 2p and N 2p states determines the valence band electronic structure away from the top. The 2p contributions from non-equivalent nitrogen sites have been identified using resonant inelastic x-ray scattering spectroscopy with the excitation energy tuned near the N 1s threshold. The binding energy of the Me 3d bands and the hybridization between N 2p and Me 3d states both increase in going across the row from Me = Mn to Me = Cu. Localization of the Cu 3d states also leads to weak screening of Cu 2p and 3s states, which accounts for shifts in the core 2p and 3s spectra of the transition metal atoms. Calculations indicate that the ground-state magnetic ordering, which varies across the series is largely dependent on the occupation of the metal 3d shell and that structural differences in the superexchange pathways for different compounds play a secondary role.Comment: 20 pages, 11 figures, 2 table

Thermal Hall conductivity of marginal Fermi liquids subject to out-of plane impurities in high-TcT_c cuprates

The effect of out-of-plane impurities on the thermal Hall conductivity $\kappa_{xy}$ of in-plane marginal-Fermi-liquid (MFL) quasiparticles in high-$T_c$ cuprates is examined by following the work on electrical Hall conductivity $\sigma_{xy}$ by Varma and Abraham [Phys. Rev. Lett. 86, 4652 (2001)]. It is shown that the effective Lorentz force exerted by these impurities is a weak function of energies of the MFL quasiparticles, resulting in nearly the same temperature dependence of $\kappa_{xy}/T$ and $\sigma_{xy}$, indicative of obedience of the Wiedemann-Franz law. The inconsistency of the theoretical result with the experimental one is speculated to be the consequence of the different amounts of out-of-plane impurities in the two YBaCuO samples used for the $\kappa_{xy}$ and $\sigma_{xy}$ measurements.Comment: 5 pages, 2 eps figures; final versio

Positivity of energy for asymptotically locally AdS spacetimes

We derive necessary conditions for the spinorial Witten-Nester energy to be well-defined for asymptotically locally AdS spacetimes. We find that the conformal boundary should admit a spinor satisfying certain differential conditions and in odd dimensions the boundary metric should be conformally Einstein. We show that these conditions are satisfied by asymptotically AdS spacetimes. The gravitational energy (obtained using the holographic stress energy tensor) and the spinorial energy are equal in even dimensions and differ by a bounded quantity related to the conformal anomaly in odd dimensions.Comment: 36 pages, 1 figure; minor corrections, JHEP versio