Observing the variation of asteroid thermal inertia with heliocentric distance

Thermal inertia is a useful property to characterise a planetary surface since it can be used as a qualitative measure of the regolith grain size. It is expected to vary with heliocentric distance because of its dependence on temperature. However, no previous investigation has conclusively observed a change in thermal inertia for any given planetary body. We have addressed this by using NEOWISE data and the Advanced Thermophysical Model to study the thermophysical properties of the near-Earth asteroids (1036) Ganymed, (1580) Betulia, and (276049) 2002 CE26 as they moved around their highly eccentric orbits. We confirm that the thermal inertia values of Ganymed and 2002 CE26 do vary with heliocentric distance, although the degree of variation observed depends on the spectral emissivity assumed in the thermophysical modelling. We also confirm that the thermal inertia of Betulia did not change for three different observations obtained at the same heliocentric distance. Depending on the spectral emissivity, the variations for Ganymed and 2002 CE26 are potentially more extreme than that implied by theoretical models of heat transfer within asteroidal regoliths, which might be explained by asteroids having thermal properties that also vary with depth. Accounting for this variation reduces a previously observed trend of decreasing asteroid thermal inertia with increasing size, and suggests that the surfaces of small and large asteroids could be much more similar than previously thought. Furthermore, this variation can affect Yarkovsky orbital drift predictions by a few tens of per cent

An Empirical Approach for Evaluating Microhabitat Response to Streamflow in Steep-Gradient, Large Bed-Element Streams

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Uptake of 3H-deoxyglucose as a microassay of human neutrophil and monocyte activation

The accumulation of 2-deoxy-D-[1-H]glucose, a non-metabolised analogue of glucose provides a quantitative measurement of the state of activation pf phagocytic cells. A microassay for H-deoxyglucose uptake by human neutrophils and monocytes is described. Optimal conditions for the assay include the use of 5 × 10 cells and 0.78 μCi/ml of deoxyglucose in a final volume of 0.2 ml per microtitre well, and an incubation time of 30 min at 37°C. This simple, rapid and reproducible technique may find application in experimental immunology