The use of soil information systems in land planning

Computerized soil information systems (SIS) store and retrieve, much more efficiently than soil maps, the soil information collected from field survey which is essential for land-use planning. The soil is only observed and sampled at a limited number of locations, depths and for a limited number of properties. Information not recorded during survey is missing and if needed must be generated or predicted. New geostatistical techniques for spatial analysis and interpolation of soil data, i.e. the semi-variogram and Kriging, can now be included as on-line capabilities of SIS to equip users with a powerful tool for prediction of the missing information. When there are no records of the wanted property, its values can be estimated by a function on other recorded properties acting as its surrogates. A strategy for model development is provided for the construction of surrogate functions based on multiple regression and curve fitting techniques, to generate the information missing. When no records of the soil property at the depth wanted exist, the values at the required depths are interpolated by a function of the property on the soil depth. Equal-area spline curves reconstruct, piecewise, the depth function quite closely, enabling their use for interpolation of values and depths in a variety of formats. The equal-area spline algorithm is a capability of the Oxford SIS (OXSIS). When the wanted site was unvisited during survey, the information missing is provided by spatial prediction. The predictions may come from means of soil classes or mapping units from conventional survey, or from Kriging interpolation based on spatial analysis by the semi-variogram. In order to select the best predictive tool, the success of these techniques in different situations of sampling effort and variablity were compared. Semi-variograms depicted the spatial structures of 8 selected soil properties. Anisotropic variation in 4 of them was induced by strong trends. Where the semi-variogram was isotropic Kriging was the best tool for prediction if spatial dependence is strong. Fitting elliptical functions to find a model for anisotropy did not give satisfactory results. Where anisotropies or trends precluded ordinary Kriging, map unit means and class means, in that order, gave the best predictions. Success in prediction was related to the structures in the semi-variogram, which when used for reconnaissance helps to infer which technique will give the best predictions so that survey is designed accordingly. Accounting for the trends removed anisotropies and Kriging of de-trended data was possible. Partitioning trends by stratification based in soil mapping units gave a greater improvement in predictions than modelling trends by bicubic spline surfaces and then Kriging the residuals from trend. After trend removal, Kriging did not always make the best predictions and means from classes seemed equally as good as Kriging or even better in some cases. These results indicate that a critical point is to ascertain how to best sample to estimate a reconnaissance semi-variogram for survey design to provide the information missing necessary for land-use planning.</p

The chemical composition of soil solutions extracted from top soils in the Oxford area

Although the soil solution lies at the centre of many of the processes which occur in soils, little information is available on the chemical composition of the soil solutions of field soils, or on the temporal and spatial variability of such solutions. The suitability of an immiscible fluid centrifugation method for obtaining samples of the soil solution was evaluated. The method was found to be substantially free from interferences and well suited to routine use. It was adapted for use with soils of low bulk density. Yields of soil solution from soils at or near field capacity ranged from 20 to 50% of the total water present. However little or no soil solution could be extracted from dry soils. Displaced solutions were analysed for about 20 solutes principally by inductively coupled plasma spectroscopy. Typical solute concentrations in soil solutons from six neutral and calcareous soil series in the Oxford area were in the range 10-2.4 to 10-3.4 M for Na, K, Ca, S, Cl, N03, alkalinity and dissolved organic carbon (DOC); 10-3.4 to 10-4.4 M for Mg, Si and P and -5.33 M for B, Li r Y, Ba, Mn, Cu, Fe, V, Zn, Al, Pb f Ni, Cd, Co, Sr and Mo. Short-range (5-10 m) variability was significantly less, and between-soil series variability significantly more, than the variability found between grass fields on the same soil series for most solutes. The main exception to this was N03 which exhibited a large between-field variability. In general, soil solutions from arable soils were more dilute than those from nearby pasture soils. Solutions from poorly drained sites on a heavy clay soil were more concentrated than those from freely draining sites on the same soil series. A year-long sampling programme showed that with the exception of P and alkalinity the concentrations of solutes in the soil solution changed significantly with time. The temporal range in the concentrations of solutes was found to increase in the order Si-Pandlt;alkalinity-Feandlt;Naandlt;Ca-Sr-Mg-Cuandlt;S-DOCandlt;K-Znandlt;Cl-pHandlt;Mn.</p

\u3ci\u3eDrosophila\u3c/i\u3e Muller F Elements Maintain a Distinct Set of Genomic Properties Over 40 Million Years of Evolution

The Muller F element (4.2 Mb, ~80 protein-coding genes) is an unusual autosome of Drosophila melanogaster; it is mostly heterochromatic with a low recombination rate. To investigate how these properties impact the evolution of repeats and genes, we manually improved the sequence and annotated the genes on the D. erecta, D. mojavensis, and D. grimshawi F elements and euchromatic domains from the Muller D element. We find that F elements have greater transposon density (25–50%) than euchromatic reference regions (3–11%). Among the F elements, D. grimshawi has the lowest transposon density (particularly DINE-1: 2% vs. 11–27%). F element genes have larger coding spans, more coding exons, larger introns, and lower codon bias. Comparison of the Effective Number of Codons with the Codon Adaptation Index shows that, in contrast to the other species, codon bias in D. grimshawi F element genes can be attributed primarily to selection instead of mutational biases, suggesting that density and types of transposons affect the degree of local heterochromatin formation. F element genes have lower estimated DNA melting temperatures than D element genes, potentially facilitating transcription through heterochromatin. Most F element genes (~90%) have remained on that element, but the F element has smaller syntenic blocks than genome averages (3.4–3.6 vs. 8.4–8.8 genes per block), indicating greater rates of inversion despite lower rates of recombination. Overall, the F element has maintained characteristics that are distinct from other autosomes in the Drosophila lineage, illuminating the constraints imposed by a heterochromatic milieu

Venous thromboembolism risk and prophylaxis in hospitalised medically ill patients The ENDORSE Global Survey

Limited data are available regarding the risk for venous thromboembolism (VIE) and VIE prophylaxis use in hospitalised medically ill patients. We analysed data from the global ENDORSE survey to evaluate VTE risk and prophylaxis use in this population according to diagnosis, baseline characteristics, and country. Data on patient characteristics, VIE risk, and prophylaxis use were abstracted from hospital charts. VTE risk and prophylaxis use were evaluated according to the 2004 American College of Chest Physicians (ACCP) guidelines. Multivariable analysis was performed to identify factors associated with use of ACCP-recommended prophylaxis. Data were evaluated for 37,356 hospitalised medical patients across 32 countries. VIE risk varied according to medical diagnosis, from 31.2% of patients with gastrointestinal/hepatobiliary diseases to 100% of patients with acute heart failure, active noninfectious respiratory disease, or pulmonary infection (global rate, 41.5%). Among those at risk for VTE, ACCP-recommended prophylaxis was used in 24.4% haemorrhagic stroke patients and 40-45% of cardiopulmonary disease patients (global rate, 39.5%). Large differences in prophylaxis use were observed among countries. Markers of disease severity, including central venous catheters, mechanical ventilation, and admission to intensive care units, were strongly associated with use of ACCP-recommended prophylaxis. In conclusion, VIE risk varies according to medical diagnosis. Less than 40% of at-risk hospitalised medical patients receive ACCP-recommended prophylaxis. Prophylaxis use appears to be associated with disease severity rather than medical diagnosis. These data support the necessity to improve implementation of available guidelines for evaluating VIE risk and providing prophylaxis to hospitalised medical patients

Venous Thromboembolism Risk and Prophylaxis in the Acute Care Hospital Setting (ENDORSE Survey) Findings in Surgical Patients

Objective: To evaluate venous thromboembolism (VTE) risk in patients who underwent a major operation, including the use of, and factors influencing, American College of Chest Physicians-recommended types of VTE prophylaxis