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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Oecologia 72 (1987), S. 21-27 
    ISSN: 1432-1939
    Keywords: Typhaeus typhoeus ; Dung beetle ; Foraging efficiency
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary This paper deals with the functional aspects of the exploitation of dung by the dung beetle Typhaeus typhoeus. In horizontal brood chambers of a nest in the soil these beetles make “dung sausages” chiefly from rabbit droppings, as a food source for the larvae. Their foraging behaviour was shown to be positively correlated with the occurrence of rainy periods. The beetles foraged more efficiently on clustered dung pellets than on dispersed ones. Body sizes of beetles were positively correlated with the lengths of the dung sausages from which they emerged. In laboratory experiments the lengths of the dung sausages made by a pair of beetles did not significantly differ within a wide range of frequencies of supply of various amounts of rabbit dung pellets, despite the longer time spent per dung sausage when less dung was supplied per unit of time. It is suggested that dung provisioning does not stop before the dung sausages have reached lengths (approximately 8.5–9.5 cm) anticipated by the lengths of the brood chambers. However, there appeared to be a critically low value between 1–2 and 4–5 dung pellets supplied per day, below which the finished dung sausages were significantly shorter (approximately 3.5 cm). When, at the places of settlement, dung was scarce near the nest entrances, the number of nest excavated by the beetles and, thus, the beetles' physical effect on the soil, was shown to be higher than when dung was plentiful near the nest. The ecological and evolutionary consequences of the foraging behaviour by the beetles are discussed.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1619-7089
    Keywords: Bone Scintigraphy ; Uptake ratio ; Osteoorosis ; Fluoride
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The reproducibility and diagnostic value of local bone to soft tissue uptake ratio of99mTc(Sn)-MDP as a bone tracer was examined in a prospective study in 35 patients who were under investigation and/or treatment for postmenopausal osteoporosis. The ratio of tracer uptake in the second lumbar vertebra (L2) and both femoral shafts was calculated from the number of counts in suitable regions of interest. Results obtained with settings and calculations in the routine practice were compared to the results obtained by revision of all raw data in one run by one person. The results were compared to the serum alkaline phosphatase activity (AP) and to local bone mineral mass as determined by dual photon absorptiometry (DPA). In 15 patients serial measurements during fluoride therapy were also compared to serum osteocalcin values and to bone histomorphomatric data. The precision error of the calculation of uptake ratios from raw counts (including selection of region of interest) was 13.9% for the femoral shaft and 14.7% for L2. The mean difference between left and right femoral shaft in individuals was not significant and its variance was smallP 〉 0.1). There was a weak but significant linear correlation between local uptake ratio in the spine and AP in the total material (r=0.328P 〈 0.01). However, changes in local uptake ratio during therapy with fluoride in 15 patients were too small to be of any value and did not correlate with changes in alkaline phosphatase or osteocalcin or trabecular surface covered with osteoblasts. We conclude therefore that local uptake ratio of bone seeking isotopes has no value in assessing general metabolic bone activity in osteoportic patients, for diagnostic purposes or in the follow up of their response to therapy, except for the detection of local untoward reactions.
    Type of Medium: Electronic Resource
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