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R Carman

Publications and source records attributed to R Carman.

7 recordsLinked to original sources
PubMed2001

Seasonal and spatial variations of carbon and nitrogen distribution in the surface sediments of the Gulf of Riga, Baltic Sea.

The variations in concentrations of carbon and nitrogen in surface sediments of the Gulf of Riga were investigated between December 1993 and January 1995. The sediment samples were taken nine times during this period at two sampling sites. One sampling site, G5, exhibited high abundance of burrowing amphipods, whereas at the second site, T3, the number of macrozoobenthic organisms was comparatively small. Similar vertical profiles of mean sediment dry-weight concentrations of total carbon (TC) and total nitrogen (TN) were obtained at both sites G5 and T3. However, during autumn winter considerable differences of TC and TN concentrations in surface sediments (0-2 cm) between sites were observed. This was probably the effect of differences in the bioturbation level. During summer, when decline in numbers of amphipods were recorded, the vertical profiles of TC and TN at site G5 were similar to those at site T3. Significant differences between months were detected for TN at site T3 reflecting sedimentation of spring and autumn blooms in April and late October-early November, respectively. This was supported also by lower atomic C/N ratios in surface sediments during corresponding sampling events.

Analysis of Variance↗
PubMed2001

Distribution and diagenesis of organic and inorganic phosphorus in sediments of the Baltic proper.

Measurements of the distribution of organic and inorganic phosphorus in the sediment have been performed at 10 sites, in the central-northern Baltic proper. Variations in deposition environment and environmental properties, such as redox chemistry and bottom water dynamics, apparently affect the distribution by altering the supply and diagenesis of organic and inorganic phosphorus constituents. The C/P and the N/P ratios of the sediment are highly divergent (higher) from the average Redfield ratio for marine living organisms at all examined sites. This indicates preferential autolytic organic phosphorus degradation and/or (deeper down in the sediment) altered input of terrestrial organic matter. The redox condition seems to affect the degradation efficiency of the organic matter since higher concentrations of C(org) occur at anoxic conditions than at oxic. At two sites significant amounts of C(inorg) have been detected indicating authigenic precipitation of carbonates. Further, authigenic precipitation of phosphate minerals also seems to occur at certain environmental conditions.

Baltic States↗
PubMed1994

Developmental profiles of spontaneous movements in infants.

Spontaneous movements were observed for 1-h sessions in each of 50 normal full-term infants aged from 2 weeks to 50 weeks in their own homes using videoanalysis. Movements were categorised according to the classifications of Thelen [17] and Hopkins and Prechtl [10]. Developmental profiles for the frequency of occurrence of the different types of movements were determined. These were found to be dependent on the posture and mobility (P < 0.05) of the infant. Developmental profiles for infants up to 6 months of age were also produced for the temporal characteristics of leg kicks and arm waves. The speed of the flexion and extension phases of both arm waves and leg kicks were found to increase significantly (P < 0.05), with a corresponding decrease in variability over age (P < 0.05). These developmental profiles may be useful in determining normal and abnormal motor behaviour in early infancy.

Arm↗
PubMed1985

Clostridial toxins active locally in the gastrointestinal tract.

Clostridium difficile and Clostridium spiroforme have only in recent years been recognized as intestinal pathogens. They both produce toxins that are also produced by other clostridia. C. difficile toxins A and B are produced by C. sordellii and a few strains of C. perfringens whereas C. spiroforme produces the same toxins as C. perfringens Type E (iota toxin). Iota toxin activity may be the product of two proteins. Toxigenic strains of C. spiroforme and Type E produce two antigens which possess much more biological activity when administered together than when given alone. C. difficile was thought for some time to produce only a single toxin, but then the enterotoxic activity was shown to be due to a separate toxin (toxin A). This toxin increases the oral toxicity of toxin B (the main cytotoxin) and may increase the permeability of the colon. Toxin A binds to a specific receptor in hamster brush border membranes and in the membranes of rabbit erythrocytes. This receptor appears to be a glycoprotein. The receptor can be extracted from the membrane with Triton and binds to immobilized toxin A. The receptor can be extracted and used to coat plastic plates as a first phase in an ELISA assay. Another assay has been developed in which the toxin A binds to the red cells and then the erythrocytes are agglutinated with antitoxin. An even more sensitive assay consists of using rabbit erythrocyte ghosts to bind the toxin and then precipitating the ghosts with antibody to toxin A attached to latex beads. Monoclonal antibodies to toxin A also have been developed and are used in these and other assays.

Animals↗
PubMed1983

The key to a key.

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Child, Preschool↗