Preliminary Testing of the Creams Erosion Sub-Model with Field Data from Silsoe, Bedfordshire, England

A preliminary investigation of the applicability of the CREAMS non-point source pollution model to British conditions was carried out by testing the erosion sub-model using field data from mid-Bedfordshire, England. With a sample of 31 storms a correlation coefficient of r=0.87 was obtained between predicted and observed values. This result is better than has been achieved using other models to predict erosion in mid-Bedfordshire and compares well with the results obtained by users of the model in the U.S.A. Three strategies are discussed and the results of the best one presented for operating the sub-model on a hillside where the overland flow and rill flow paths are approximately parallel. The results imply that the channel flow component may need to be redefined to include as channels convergent flow paths within the overland flow

Stability of Agricultural Ecosystems: Application of a Simple Model for Soil Erosion Assessment

The stability of the erosion system in a tropical rain forest environment is investigated using the model previously described by Morgan, Morgan and Finney (1982) and validated by Morgan and Finney (1982). Simulations are carried out for the natural primary forest cover, commercial timber extraction and the agricultural ecosystems of rubber cultivation, shifting cultivation with sixteen-year, fourteen-year and four-year cycles, and continuous rotational cropping of groundnuts, maize and potatoes. The model is operated for five slope steepnesses using a hundred-year synthetic sequence of rainfall data generated by Monte Carlo analysis. Erosional stability is expressed in terms of changes in rooting or top soil depth. Using the model it is possible to distinguish between three broad states of biostasy, rhexistasy and homeostasy, representing increasing, decreasing and stable rooting depths respectively. Detailed examination of the magnitudes of the change in rooting depth in response to perturbations in the system and the length of time required for recovery can show the extent to which systems in a state of or close to homeostasy are potentially unstable

Stability of Agricultural Ecosystems: Documentation of a Simple Model for Soil Erosion Assessment

Documentation is presented of a model for assessing the stability of the soil erosion component of an agricultural ecosystem. The model uses a simplified version of the Meyer-Wischmeier approach to predict the annual rate of soil erosion by water on hillslopes and this is compared with the rates of weathering and top soil renewal to determine changes in the depth of the soil profile and the top soil or rooting layer. Erosion is taken to be the result of splash detachment and runoff transport. Splash detachment is related to rainfall energy and rainfall interception by the crop. Runoff volume and sediment transport capacity are estimated from equations first presented by Kirkby. The results of trials with the model in the Silsoe area of Bedfordshire, England, show that realistic values of runoff and erosion are obtained for a range of soil and crop conditions. The model can be used to assess the stability of the erosion system under existing landuse conditions and to determine what changes need to be made in the erosion system to produce stability when unstable conditions are predicted

Molecular and morphological characterization of Echinococcus granulosus of human and animal origin in Iran

Iran is an important endemic focus of cystic hydatid disease (CHD) where several species of intermediate host are commonly infected with Echinococcus granulosus. Isolates of E. granulosus were collected from humans and other animals from different geographical areas of Iran and characterized using both DNA (PCR-RFLP of ITS1) and morphological criteria (metacestode rostellar hook dimensions). The sheep and camel strains/genotypes were shown to occur in Iran. The sheep strain was shown to be the most common genotype of E. granulosus affecting sheep, cattle, goats and occasionally camels. The majority of camels were infected with the camel genotype as were 3 of 33 human cases. This is the first time that cases of CHD in humans have been identified in an area where a transmission cycle for the camel genotype exists. In addition, the camel genotype was found to cause infection in both sheep and cattle. Results also demonstrated that both sheep and camel strains can be readily differentiated on the basis of hook morphology alone

A second look at the toric h-polynomial of a cubical complex

We provide an explicit formula for the toric $h$-contribution of each cubical shelling component, and a new combinatorial model to prove Clara Chan's result on the non-negativity of these contributions. Our model allows for a variant of the Gessel-Shapiro result on the $g$-polynomial of the cubical lattice, this variant may be shown by simple inclusion-exclusion. We establish an isomorphism between our model and Chan's model and provide a reinterpretation in terms of noncrossing partitions. By discovering another variant of the Gessel-Shapiro result in the work of Denise and Simion, we find evidence that the toric $h$-polynomials of cubes are related to the Morgan-Voyce polynomials via Viennot's combinatorial theory of orthogonal polynomials.Comment: Minor correction

Stability of Agricultural Ecosystems: Validation of a Simple Model for Soil Erosion Assessment

Validation trials of the model described by Morgan, Morgan and Finney (1982) for assessing the stability of the soil erosion component of an agricultural ecosystem were carried out using data from published studies of soil loss for 67 sites in 12 countries. Correlation coefficients of 0.74 and 0.58 were obtained between predicted and observed values of runoff at 56 sites and soil loss at 67 sites respectively. If two poor predictions of very high erosion rates in China are omitted, the value of the correlation coefficient for soil loss rises to 0.67 and the slope of the reduced major axis regression line is not significantly different from unity. The success of the model was also evaluated against the criteria that it should predict whether or not there was likely to be an erosion problem and if there was, that it should predict the magnitude of the problem. Against these criteria, the model was successful on 59 per cent of the tests for runoff and 70 percent of the tests for soil loss. Considering only those sites for which high quality input data were available, the success rate for soil loss rose to 90 per cent. Guidelines are presented for the selection of parameter values for rainfall intensity, weathering rates, soil renewal rates and rooting depth

Laser damage database at 1064 nm

In conjunction with our diversification of laser damage testing capabilities, we have expanded upon a database of threshold measurements and parameter variations at 1064 nm. This includes all tests at low pulse-repetition frequencies (PRF) ranging from single shots to 120 Hz. These tests were conducted on the Reptile laser facility since 1987 and the Variable Pulse Laser (VPL) facility since 1988. Pulse durations ranged from 1 to 16 ns. 10 refs., 14 figs

THE INTERPLAY OF THE K+K- ATOM AND THE f_0(975) RESONANCE

We predict that production of the K+K- atom in pd-3^HeX and similar reactions exhibits a drastic missing mass spectrum due to the interplay with f_0(975) resonance. We point out that high precision studies of the K+K- atom may shed a new light on the nature of f_0(975).Comment: 13 page

Phase Separation in Lix_xFePO4_4 Induced by Correlation Effects

We report on a significant failure of LDA and GGA to reproduce the phase stability and thermodynamics of mixed-valence Li$_x$FePO$_4$ compounds. Experimentally, Li$_x$FePO$_4$ compositions ($0 \leq x \leq 1$) are known to be unstable and phase separate into Li FePO$_4$ and FePO$_4$. However, first-principles calculations with LDA/GGA yield energetically favorable intermediate compounds an d hence no phase separation. This qualitative failure of LDA/GGA seems to have its origin in the LDA/GGA self-interaction which de localizes charge over the mixed-valence Fe ions, and is corrected by explicitly considering correlation effects in this material. This is demonstrated with LDA+U calculations which correctly predict phase separation in Li$_x$FePO$_4$ for $U-J \gtrsim 3.5$eV. T he origin of the destabilization of intermediate compounds is identified as electron localization and charge ordering at different iron sites. Introduction of correlation also yields more accurate electrochemical reaction energies between FePO$_4$/Li$_x$FePO$_ 4$ and Li/Li$^+$ electrodes.Comment: 12 pages, 5 figures, Phys. Rev. B 201101R, 200

Displaying the Heterogeneity of the SN 2002cx-like Subclass of Type Ia Supernovae with Observations of the Pan-STARRS-1 Discovered SN2009ku

SN2009ku, discovered by Pan-STARRS-1, is a Type Ia supernova (SNIa), and a member of the distinct SN2002cx-like class of SNeIa. Its light curves are similar to the prototypical SN2002cx, but are slightly broader and have a later rise to maximum in g. SN2009ku is brighter (~0.6 mag) than other SN2002cx-like objects, peaking at M_V = -18.4 mag - which is still significantly fainter than typical SNeIa. SN2009ku, which had an ejecta velocity of ~2000 kms^-1 at 18 days after maximum brightness is spectroscopically most similar to SN2008ha, which also had extremely low-velocity ejecta. However, SN2008ha had an exceedingly low luminosity, peaking at M_V = -14.2 mag, ~4 mag fainter than SN2009ku. The contrast of high luminosity and low ejecta velocity for SN2009ku is contrary to an emerging trend seen for the SN2002cx class. SN2009ku is a counter-example of a previously held belief that the class was more homogeneous than typical SNeIa, indicating that the class has a diverse progenitor population and/or complicated explosion physics. As the first example of a member of this class of objects from the new generation of transient surveys, SN2009ku is an indication of the potential for these surveys to find rare and interesting objects.Comment: 7 pages, 3 figure