Hydrochemical processes at a pristine site in nord-trøndelag,mid-Norway

A detailed study of hydrochemical processes associated with vegetation and soils was undertaken at a pristine site in mid-Norway. Inputs to the site during snow-free periods showed a marked seasonality with excess sulphate concentrations in rainfall only during the summer months. However, this represented a small fraction of total annual loading and there was a dominant influence of sea salt deposition. Site vegetation modified the chemistry of water reaching the soil surface, and this also showed a marked seasonal response. The pristine nature of this site results in the soils retaining acid-soluble components which may have been eluted from impacted sites. In the soils, the extractable aluminium remains largely (70%) in the organic bound forms. The contribution of different sources of water in affecting streamwater output quality at this site are discussed.     

The Contribution to Nitrogen Deposition and Ozone Formation in South Norway from Atmospheric Emissions Related to the Petroleum Activity in the North Sea

A photochemical puff-trajectory model (Fotoplume) has been applied to simulate emissions, atmospheric transport and chemical transformations of pollutants from offshore oil and gas production in the North Sea. The above model was used in conjunction with the European Monitoring and Evaluation Programme (EMEP) regional Lagrangian oxidant model. The Fotoplume and EMEP models were used to evaluate the effects of the atmospheric emissions from the oil and gas exploration activity in the Norwegian sector of the North Sea. Deposition of nitrogen and formation of boundary level ozone in Southern Norway due to North Sea emissions of nitrogen oxides (NO_x), carbon monoxide (CO) and volatile organic compounds (VOC) have been studied. The petroleum activity in the North Sea is calculated to contribute approximately 20% of the nitrogen deposition in the coastal areas of Norway in 1992. In addition, the models were used to estimate the AOT40 ozone exposure levels. The results indicate that emissions from British and Norwegian oil and gas exploitation sector separately contribute to less than 5% each of the AOT40 values for coniferous forests and meadows. Comparison of model calculations with experimental measurements is quite satisfactory and the models show realistic results for both the nitrogen deposition and AOT40 values.     

Textural differentiation in chronosequences from eastern australia,II. evidence from particle-size distributions

Data from particle-size analyses were used to determine the relative importance of the four mechanisms proposed to explain the development of strong textural contrast in the end members of four chronosequences. The mechanisms proposed were sedimentary layering, in-situ chemical weathering, clay illuviation and physical breakdown.Depth functions of fine clay: total clay ratios and detailed particle-size distributions at ø intervals from 0.6 μm to 2000 μm indicated that there had been a marked increase in fine clay in the B horizons of the older soils of each sequence, a result consistent with, but not proving, a clay illuviation hypothesis. Cumulative particle-size distribution indices showed that most profiles had texturally uniform parent materials. Changes in the ratio fine silt : total silt with depth were slight for all but one profile, indicating no significant contribution to the clay fraction by in-situ chemical weathering of the silt fraction.From changes in the depth functions of gravel with time, it was concluded that physical breakdown had occurred but that it had not been responsible for the development of the textural B horizon. The rate of disintegration was particularly high early in pedogenesis, preceding the development of texture-contrast. Breakdown contributed fines to the whole solum and was not generally any more intense in one horizon than another. Grain counts of rock fragments in the medium sand range lent support to this conclusion.Changes in the particle-size distribution of quartz from 0.2 μm to 2000 μm indicated that the contribution to the clay fraction from physical disintegration was only slight.     

Breast-feeding in sub-Saharan Africa: outlook for 2000

The World Health Organization (WHO) has stressed that 1.5 million infants die annually, unnecessarily, from deprival or from insufficiency of breast milk. Hence, the need for its maximal use, very particularly in impoverished populations, such as those in sub-Saharan Africa. In many developed populations, a generation ago the practice was very low, but now it has risen considerably. In contrast, in Africa and in most developing populations, despite the far greater need for breast-feeding, the practice is tending to decrease, especially among urban mothers. While the most common reasons given concern insufficiency of breast milk and employment of mothers, the latter, especially urban mothers, are under strong and increasing pressure to use proprietary replacement foods. These are often made up unsatisfactorily and are contaminated. Also influential are the often less than enthusiastic, and confusing, attitudes of staff at clinics and hospitals, albeit, due in part to their very heavy workloads. Additionally, there is society's relatively indifferent attitude to breast-feeding. Currently, a hugely adverse factor is the danger of human immunodeficiency virus (HIV) transference from seropositive mothers to their infants - in some African countries almost half of antenatal mothers are infected. Chances of early control of the infection are remote. However, apart from this danger, and from the pressure from replacement food companies, the outlook for breast-feeding practice in many African countries is unlikely to improve significantly until greater encouragement is given from State, local and other health authorities.     

IRIDIUM-192: A LITERATURE REVIEW FOR FURTHER REFERENCING THE ISOTOPE, ITS ACTIVITY UNITS, AND DOSIMETRY TECHNIQUES

The individual embarking on an iridium-192 brachytherapy program is faced with an abundance of concepts, terms and dosimetry techniques. This article introduces the beginning brachytherapist to the basic physical parameters of iridium-192, to the potential units for source strength and to the general concepts of the various dosimetry techniques. Multiple literature references are listed for more in-depth study.     

Attenuation of Borrelia anserina by serial passage in liquid medium

Borrelia anserina (Sakharoff) was successfully grown in a liquid medium (Barbour-Stoenner-Kelly) for 39 passages. By the 12th serial passage in medium, infectivity of B anserina for chicks was lost. Electron microscopy did not reveal structural differences between non-infective and infective cultured organisms. Changes in the protein profiles were found by electrophoresis as the organisms were passed in culture.     

Granulocyte plasma membrane damage by leukotoxic supernatant from Pasteurella haemolytica A1 and protection by immune serum.

Bovine respiratory disease caused by Pasteurella haemolytica may be partially mediated by a leukotoxin secreted by the microorganism. We examined the effect of leukotoxic Pasteurella supernatants on leakage of the cytosol enzyme lactate dehydrogenase and the lysosomal enzyme arylsulfatase from bovine granulocytes. Lactate dehydrogenase release (94%) was much higher than arylsulfatase release (38%) over 30 minutes of incubation. The Pasteurella supernatants inhibited superoxide production by stimulated granulocytes at concentrations which also caused substantial cell death as measured by failure to exclude trypan blue. Both toxic effects were prevented by serum from aerosol-immunized calves, and protection appeared to be antibody-specific by comparison with fetal bovine serum or with serum absorbed against intact P. haemolytica. These findings suggest that the leukotoxin may selectively disrupt the granulocyte plasma membrane, and that antibody directed against a surface component of the microorganism is also capable of protecting against the leukotoxin effect.     

Isolation of Gardnerella vaginalis from the reproductive tract of four mares

A gram-variable pleomorphic bacillus was isolated from the reproductive tracts of 4 mares during routine prebreeding soundness examinations. Using a commercial bacterial identification system, these organisms were identified as Streptococcus acidominimus. However, colonial and Gram-staining characteristics did not support this identification. Subsequent testing indicated the organism was similar to Gardnerella vaginalis. Additional growth and biochemical analysis performed in our laboratory and at the Michigan Department of Public Health and by the Center for Disease Control, Atlanta, Georgia, confirmed the identification of G. vaginalis.     

MAGNETIC RESONANCE IMAGING OF THE BRAIN OF NORMAL NEONATAL FOALS

Magnetic resonance imaging (MRI) was performed on gthe brain of 5 normal, anesthetized, neonatal (age 3-to-6 days) Quarter Horse foals. The objectives of the study were to develop a technique for imaging the brain of neonatal foals, and to ascertain their normal brain anatomy. Interavenous propofol was administered for induction and maintenance of general anesthesia. Using spin echo MR techniques, T1 weighted sagittal and transverse views, and spin density and T2 weighted transverse views were successfully made of each foal. MR images provided excellent visualization of many anatomic struictures of the brain and head. MRI of the bgrain is feasible for selected neonantal equine patients.     

A tracheoscopic technique for obtaining uncontaminated lower airway secretions for bacterial culture in the horse

Transtracheal aspirate (TTA) aerobic microbiology culture results from 30 ponies were compared to protected catheter brush (PCB) culture results obtained from the same ponies. The PCB procedure resulted in significantly fewer (P less than 0.05) isolates than those obtained by the TTA procedure and the PCB procedure resulted in significantly more samples with no bacteria growth than the TTA procedure. To address the possibility that the volume of tracheobronchial secretion obtained by PCB was insufficient as a microbiological sample, a sterile, double-sheathed, protected aspiration catheter (PAC) was developed. Comparisons were made between TTA and PAC aerobic microbiology culture results from 18 pneumonic foals and weanlings. There were no significant differences between the PAC and TTA procedures with respect to the number of bacteria isolates. It was concluded that the PAC technique may be used as an alternative to TTA for isolation of equine pulmonary bacteria and may be the preferred procedure because of the reduced risk of complications associated with the TTA.