Radionuclides in the water column at stations near the Antarctic Polar Front in the South Atlantic

Vertical profiles of dissolved and particulate 230Th and 231Pa were obtained across the Antarctic Circumpolar Current (ACC) in the southern Atlantic. North of the Polar Front, dissolved and total 230Th increase with depth in conformity with published scavenging models. There is no depletion of 230Th or 231Pa in the water column south of the Polar Front, thought to be an area of enhanced biological productivity. 230Th concentrations increase three-fold to the Weddell Sea across the ACC. Dissolved and total 231Pa concentrations are relatively constant below 500 m depth at about 0.3 dpm m**-3, and change little with depth or latitude. The results from the Weddell Gyre are explained by a mixing-scavenging model that takes into account the input of lower Circumpolar Deep Water through upwelling, which is the main source of water in the Weddell Gyre and is enriched in 230Th but not in 231Pa. 230Th accumulates in the Weddell Gyre as a result of a reduction in the scavenging rate and by ingrowth from 234U. Ingrowth is more significant for 230Th than for 231Pa because the residence time of water in the gyre (about 35 years) is similar to the scavenging residence time of Th in the south Atlantic (29 years) but shorter than that of Pa (120 years). It is argued that changes in 230Th accumulation in the past may reflect changes in water residence time and in the formation rate of Weddell Sea Deep Water.

A biological investigation of the Kishwaukee River and its tributaries (segment A-02 of the Rock River Basin April-July, 1976 /

Bibliography: p. 37.

Biological and water quality survey of the Carroll Creek Watershed, Carroll County, Illinois, 1987-1988.

"IEPA/WPC/89-163."--Cover.

Bulletin - University of Florida, Agricultural Experiment Stations.

Separately cataloged in L.C. after Mar. 1958.

The North Pacific biological pump: Rates, efficiency and influence on ocean carbon uptake

Thesis (Ph.D.)--University of Washington, 2016-05

Annotated record of the detailed examination of Mn deposits from R/V Velero IV Cruise 404 stations

The geographical, physical and biological aspects of the submarine canyons of the continental shelf off the coast of southern California have been described in earlier parts of this volume. Isopods were collected in 10 of the 15 canyons. Many benthic species were obtained since the specimens were obtained with a Campbell grab bottom sampler operated from the Hancock Foundation research vessel Velero IV.

Annotated record of the detailed examination of Mn deposits from CLIMAX I Expedition stations

The cores described in this report were taken on the CLIMAX I Expedition in September 1968 by the Scripps Institution of Oceanography from the R/V Horizon. A total of 3 cores were recovered and are available at Scripps for sampling and study.

Soil investigations at Casey and Arctowski stations

Soils from the maritime (Arctowski Station, King George Island) and coastal continental (Casey Station, Wilkes Land) Antarctic region are described with respect to pedology, isotopic and microbial environments. They are classified as leptosols, regosols, podzols, and histosols. Only surface layers (1-3 cm) contain sufficient organic material to provide a favourable environment for microbial communities and, further, for accumulations of organic matter. Variability of biological and chemical properties is high on a centimeter scale with depth and in the range of decimeters in horizontal scales.

Improving behaviour classification consistency: a technique from biological taxonomy

Quantitative behaviour analysis requires the classification of behaviour to produce the basic data. In practice, much of this work will be performed by multiple observers, and maximising inter-observer consistency is of particular importance. Another discipline where consistency in classification is vital is biological taxonomy. A classification tool of great utility, the binary key, is designed to simplify the classification decision process and ensure consistent identification of proper categories. We show how this same decision-making tool - the binary key - can be used to promote consistency in the classification of behaviour. The construction of a binary key also ensures that the categories in which behaviour is classified are complete and non-overlapping. We discuss the general principles of design of binary keys, and illustrate their construction and use with a practical example from education research.

Development of a biaxial compression device for biological samples : preliminary experimental results for a closed cell foam

Biological tissues are subjected to complex loading states in vivo and in order to define constitutive equations that effectively simulate their mechanical behaviour under these loads, it is necessary to obtain data on the tissue's response to multiaxial loading. Single axis and shear testing of biological tissues is often carried out, but biaxial testing is less common. We sought to design and commission a biaxial compression testing device, capable of obtaining repeatable data for biological samples. The apparatus comprised a sealed stainless steel pressure vessel specifically designed such that a state of hydrostatic compression could be created on the test specimen while simultaneously unloading the sample along one axis with an equilibrating tensile pressure. Thus a state of equibiaxial compression was created perpendicular to the long axis of a rectangular sample. For the purpose of calibration and commissioning of the vessel, rectangular samples of closed cell ethylene vinyl acetate (EVA) foam were tested. Each sample was subjected to repeated loading, and nine separate biaxial experiments were carried out to a maximum pressure of 204 kPa (30 psi), with a relaxation time of two hours between them. Calibration testing demonstrated the force applied to the samples had a maximum error of 0.026 N (0.423% of maximum applied force). Under repeated loading, the foam sample demonstrated lower stiffness during the first load cycle. Following this cycle, an increased stiffness, repeatable response was observed with successive loading. While the experimental protocol was developed for EVA foam, preliminary results on this material suggest that this device may be capable of providing test data for biological tissue samples. The load response of the foam was characteristic of closed cell foams, with consolidation during the early loading cycles, then a repeatable load-displacement response upon repeated loading. The repeatability of the test results demonstrated the ability of the test device to provide reproducible test data and the low experimental error in the force demonstrated the reliability of the test data.

Biological performance of a polycaprolactone-based scaffold used as fusion cage device in a large animal model of spinal reconstructive surgery

A bioactive and bioresorbable scaffold fabricated from medical grade poly (epsilon-caprolactone) and incorporating 20% beta-tricalcium phosphate (mPCL–TCP) was recently developed for bone regeneration at load bearing sites. In the present study, we aimed to evaluate bone ingrowth into mPCL–TCP in a large animal model of lumbar interbody fusion. Six pigs underwent a 2-level (L3/4; L5/6) anterior lumbar interbody fusion (ALIF) implanted with mPCL–TCP þ 0.6 mg rhBMP-2 as treatment group while four other pigs implanted with autogenous bone graft served as control. Computed tomographic scanning and histology revealed complete defect bridging in all (100%) specimen from the treatment group as early as 3 months. Histological evidence of continuing bone remodeling and maturation was observed at 6 months. In the control group, only partial bridging was observed at 3 months and only 50% of segments in this group showed complete defect bridging at 6 months. Furthermore, 25% of segments in the control group showed evidence of graft fracture, resorption and pseudoarthrosis. In contrast, no evidence of graft fractures, pseudoarthrosis or foreign body reaction was observed in the treatment group. These results reveal that mPCL–TCP scaffolds could act as bone graft substitutes by providing a suitable environment for bone regeneration in a dynamic load bearing setting such as in a porcine model of interbody spine fusion.