Dissolved organic carbon losses from grazed grasslands under different management regimes

Dissolved organic matter (DOM) is fundamental to many biogeochemical processes in soils and natural waters. Despite the large number of studies reporting on DOM losses from forest soils and in surface waters there is little published data on exports from managed grasslands. The objective of our study was to determine the extent of short-term exports of dissolved organic carbon (DOC) from managed grazed grasslands and to evaluate the influence of fertilizer management and drainage regime. DOC discharged from grazed grassland plots, with a range of management strategies. was determined over 2 months. Total export varied from 42 to 118 kgCha(-1), and was greater from some plots than literature estimates for annual losses from all catchment types. There was a significant (P = 0.048) positive correlation between DOC export and rates of nitrogen application for treatments with no artificial drainage. Increased dry matter production arising from increased fertilizer-N inputs is suggested as an important factor in this relationship. DOC export was significantly (P = 0.032) reduced by artificial drainage and adsorption of DOC to soil surfaces and the restriction of decomposition due to waterlogging are suggested as two possible explanations.

Stereo image coding: a projection approach

Recently, due to advances in display technology, three-dimensional (3-D) imaging systems are becoming increasingly popular. One way of stimulating 3-D perception is to use stereo pairs, a pair of images of the same scene acquired from different perspectives. Since there is an inherent redundancy between the images of a stereo pair, data compression algorithms should be employed to represent stereo pairs efficiently. This paper focuses on the stereo image coding problem. We begin with a description of the problem and a survey of current stereo coding techniques. A new stereo image coding algorithm that is based on disparity compensation and subspace projection is described. This algorithm, the subspace projection technique (SPT), is a transform domain approach with a space-varying transformation matrix and may be interpreted as a spatial-transform domain representation of the stereo data. The advantage of the proposed approach is that it can locally adapt to the changes in the cross-correlation characteristics of the stereo pairs. Several design issues and implementations of the algorithm are discussed. Finally, we present empirical results suggesting that the SPT approach outperforms current stereo coding techniques.

Glutathione deficiency does not elevate susceptibility of bacteria to the mutagenicity of chlorinated humic acids

1. Rat liver 9,000 g supernatant protected against the mutagenic effect of chlorinated hydrophilic macromolecular humic acids (CHMA) in Salmonella typhimurium strain TA100. 2. Protection against mutagenicity of CHMA was mediated by glutathione and was partially dependent on glutathione S-transferase activity. 3. In contrast to the above findings, CHMA showed lower mutagenicity in Salmonella typhimurium and Escherichia coli strains of bacteria that are deficient in glutathione compared to their mutagenicity in parental (glutathione-rich) bacterial strains. 4. Glutathione-deficient cells do not provide test systems with elevated sensitivity for the detection of mutagenic chlorinated humic substances.

An analysis of a melanoma epidemic

Between 1986 and 1988 the annual incidence of invasive melanoma in the Hunter area of New South Wales, Australia, almost doubled to 52.5 per 100,000 in men and 42.9 per 100,000 in women. These rates have been maintained and are similar to those reported for 1987 in Queensland, Australia, which are the highest in the world. Most of the increase in incidence was in melanomas less than 1.50 mm in thickness, and adults of both sexes and all ages were affected. Thicker melanomas also increased in incidence but only in adults 45 years and older, and mainly in men. An analysis of health insurance data on treatment of skin lesions and data from a histopathology laboratory suggested that diagnosis and treatment of skin lesions generally in the Hunter area had increased almost 2-fold over this period. Advancement of the time of diagnosis and a real increase in incidence were likely explanations for some of the observed trends. Increasing diagnosis of a non-metastasising form of thin melanoma, consequent upon increasing removal of pigmented skin lesions by medical practitioners, may also explain some of the observed increase in the incidence of the disease. This possibility has important implications for proposed population screening programs, and methods are needed to distinguish such lesions, if they exist, from potentially fatal melanoma.

Use of readily available data for identifying local health care needs and resources

Health departments everywhere are struggling to balance shrinking resources against increasing requests for services. According to the Institute of Medicine report, The Future of Public Health, one of the barriers to solving public health problems is "... disjointed decision-making without necessary data and knowledge ..." (p. 107). Leadership of the Middle Tennessee Region of the Tennessee Department of Health have addressed this issue by developing a practical, usable data base from which to consider the needs and resources of the region.