Phosphorus content in soil, uptake by plants and balance in three European long-term field experiments

The fate of phosphorus (P) derived from mineral fertilisers and organic manures, and the effective P balance, have been assessed in three long-term field experiments at Rothamsted (UK), Bad Lauchstaedt (Germany) and Skierniewice (Poland). This paper discusses the plant availability, uptake and overall utilisation of P over the last 30 years, based on soil test P availability indices and crop analyses determined by the standard methods used in each of the three countries. The data suggest that differences in soil type significantly influence the dynamics of P at the three locations, but most significantly between a loess Chernozem at Bad Lauchstaedt with a high organic matter content and the soils at the other two locations which have a low organic matter content. The application of P either as inorganic fertiliser or organic manure had a considerable influence on the availablity, uptake, leaching or fixing of P, but the crop recovery rate of P from mineral fertiliser did not exceed 35% with the smallest recovery (average 18%) occurring in the soil with the highest clay content at Rothamsted. At Bad Lauchstaedt and Rothamsted the most efficient utilisation of P (averages of 47% and 37%, respectively) was from soils treated with farmyard manure (FYM), with the greater quantity of P either leached or fixed (8 and 25 kg ha^-1 y^-1, respectively) occurring in soils treated with superphosphate. At Skierniewice, however, the reverse was true. Overall, the most efficient crop utilisation from mineral P (30% average) was from the loamy sand at Skierniewice. P balances for the three locations show that quantitatively, for the same P input, the amount of P either leached from or fixed in the plough layer of Broadbalk field, Rothamsted, was 2–3 times greater than at Skierniewice and 3–6 times greater than at Bad Lauchstaedt. The results suggest that differences in the soil physico-chemical properties, climate, the availability of other major nutrients, and the form in which P is applied, all influence the effectiveness of P fertilisation and P balance. The investigation highlights the importance of maintaining long-term field experiments and archived soil and crop samples on a world-wide basis for understanding nutrient cycling and fertility dynamics.     

Signal Processing for Semiconductor Detectors

This is a tutorial paper designed to provide a balanced perspective on the processing of signals produced by semiconductor detectors. The general problems of pulse shaping to optimize resolution with constraints imposed by noise, counting rate and rise time fluctuations are discussed.     

Estimation of timber volume in a coniferous plantation forest using Landsat TM

Optimisation of economic return from forests requires that comprehensive forest inventory data be available to support the design of harvesting strategies. Such inventory data can potentially be obtained by remote sensing. This study investigates the accuracy with which wood volume (m3 ha -1) in a plantation forest can be calculated from Landsat TM data at the pixel and foreststand spatial scales. Wood volumes were estimated from regression analysis, nonparametric line-fitting, and an N-dimensional K-nearest-neighbour classification scheme. At the pixel scale, relations between Landsat data and measured wood volume were found to be significant but weak, with r2 values of 0.3, and with correspondingly poor estimates of wood volume (root-mean-square errors rmses of 100 m3 ha -1). By averaging the pixel-scale estimates, wood volume estimates of acceptable accuracy were obtained for forest-stand areas of about 40 ha (rmses of 46 m3 ha -1). Parametric regression performed slightly better overall than non-parametric line fitting techniques for estimating wood volume. Estimates of similar accuracy to those obtained by regression were also given by NK-classification at the pixel-scale, provided K was large ( 15), although the classifier produced biased results at the forest-stand scale. It is concluded that Landsat TM only provides an acceptable data source for estimating wood volumes in plantation forests for areas of about 40 ha and larger. The very low dynamic range in the Landsat data is probably a significant factor limiting its use for inventory at more detailed scales.     

Minimising conservatism in infinite-horizon LQR control

This paper studies the formulation of the constrained infinite horizon linear quadratic regulator control law (CIHLQR). Results from recent studies in this area are extended to show that conditions used in the standard formulation of the CIHLQR law are not necessary, but merely sufficient. Through the use of a novel proof it is shown that for a general SISO system with input constraints and certain conditions imposed, saturated LQR provides the same control sequence as CIHLQR. It is further shown that saturated LQR is equivalent to the CIHLQR in the case of first-order systems, subject to both state and control constraints. Finally, the region of constrained stabilisability is characterised for the case of open-loop unstable first-order systems.     

Bone marrow transplantation for the treatment of alpha-mannosidosis

BACKGROUND: Traditionally, elderly donor kidneys have not been widely accepted for transplantation on the assumption of inferior performance. However, the United Network for Organ Sharing reports an increase in the number of elderly donors from less than 2% in 1982 to 24% in 1995. This trend is commensurate with the increase of older dialysis patients and an overall increase in the elderly population in the United States (1). Optimal utilization of these kidneys is essential to overcome the acute organ shortage. METHODS: In this study, we transplanted 25 kidneys from elderly donors (ages 56-72 years) into young adult recipients (ages 20-50 years) (group 1) over a 4-year period. We compared the results with matched recipients of young adult donor kidneys (group 2) with regard to long-term kidney function and graft survival. A pretransplant biopsy of elderly donor kidneys was carried out and a frozen section report was obtained. Only those kidneys showing glomerulosclerosis of less than 20% were accepted for transplantation. All cadaveric kidneys were preserved in University of Wisconsin solution. RESULTS: Pretransplant biopsies of elderly donor kidneys showed structural deficits, which included glomerulosclerosis in 85%, arteriolar and/or mesangial thickening in 75%, and interstitial lymphocyte infiltration in 30%. The mean serum creatinine was 2.4+/-0.74, 2.2+/-0.56, and 2.9+/-0.76 mg/100 ml in group 1 and 1.5+/-0.55, 2.3+/-2.24, and 1.7+/-0.62 in group 2 at 1, 3, and 5 years, respectively. The patient survival was 92%, 92%, and 88% in group 1, and 100%, 100%, and 100% in group 2 at 1, 3, and 5 years, respectively. The graft survival was 80%, 64%, and 56% in group 1 and 100%, 96%, and 88% in group 2 at similar time intervals. The differences in the serum creatinine and graft survival between the two groups were statistically significant (P < 0.05). CONCLUSIONS: Most of the elderly donor kidneys with structural deficits transplanted into young adults provided suboptimal function and inferior long-term graft survival. To maximize the utilization and optimize the survival of elderly donor kidneys, we propose transplantation of these kidneys into age-matched recipients with similar physiological requirements as those of donors, with regard to kidney function.     

Plasma leptin values in relation to bone mass and density and to dynamic biochemical markers of bone resorption and formation in postmenopausal women

A case of measles in a 26-year-old Japanese man is reported. A skin specimen taken on the third eruptive day from a maculopapular eruption on his chest was immunohistopathologically and electron microscopically examined using a rabbit polyclonal antibody against the nucleocapsid protein of the measles virus. The measles virus antigen was found in the inner cells of the acrosyringium and hair follicles. The measles virus nucleocapsid was electron microscopically identified in the nuclei of the inner cells of the acrosyringium. The findings suggest that the sweat from skin lesions might contain the measles virus.     

Nitrogen input, <Superscript>15</Superscript>N balance and mineral N dynamics in a rice–wheat rotation in southwest China

A field experiment and farm survey were conducted to test nitrogen (N) inputs, ¹⁵N-labelled fertilizer balance and mineral N dynamics of a rice–wheat rotation in southwest China. Total N input in one rice–wheat cycle averaged about 448 kg N ha⁻¹, of which inorganic fertilizer accounted for 63% of the total. The effects of good N management strategies on N cycling were clear: an optimized N treatment with a 27% reduction in total N fertilizer input over the rotation decreased apparent N loss by 52% and increased production (sum of grain yield of rice and wheat) compared with farmers’ traditional practice. In the ¹⁵N-labelled fertilizer experiment, an optimized N treatment led to significantly lower ¹⁵N losses than farmers’ traditional practice; N loss mainly occurred in the rice growing season, which accounted for 82% and 67% of the total loss from the rotation in farmers’ fields and the optimized N treatment, respectively. After the wheat harvest, accumulated soil mineral N ranged from 42 to 115 kg ha⁻¹ in farmers’ fields, of which the extractable soil NO₃ ⁻–N accounted for 63%. However, flooding soil for rice production significantly reduced accumulated mineral N after the wheat harvest: in the ¹⁵N experiment, farmers’ practice led to considerable accumulation of mineral N after the wheat harvest (125 kg ha⁻¹), of which 69% was subsequently lost after 13 days of flooding. Results from this study indicate the importance of N management in the wheat-growing season, which affects N dynamics and N losses significantly in the following rice season. Integrated N management should be adopted for rice–wheat rotations in order to achieve a better N recovery efficiency and lower N loss.