David Rees

Bio: David Rees is an academic researcher from University College London. The author has contributed to research in topics: Thermosphere & Earth's magnetic field. The author has an hindex of 42, co-authored 161 publications receiving 6070 citations.

A Three-Dimensional Time-Dependent Global Model of the Thermosphere

Abstract: A global, three-dimensional, time-dependent numerical model of the thermosphere has been created to simulate the dynamical behavior of the earth's thermosphere under a wide variety of geophysical conditions. Comparison of the model's predictions with the available data from ground-based, rocket and satellite techniques has shown that thermospheric dynamics can be realistically simulated by considering only three processes which deposit energy, or energy and momentum, in the thermosphere. Comparisons between the simulations and available data allow assessment of the magnitudes of the various processes as functions, particularly, of solar and geomagnetic activity. The model is fully self-consistent in solving the neutral gas equations of momentum, energy and continuity, including all the Coriolis, inertial, viscosity and nonlinear terms, but assumes that the thermosphere contains a single species whose mean molecular weight varies only with the pressure. At times when the mean meridional wind is la...

Interactions between neutral thermospheric composition and the polar ionosphere using a coupled ionosphere‐thermosphere model

Abstract: A fully self-consistent numerical model of the polar ionosphere and the global thermosphere has been developed to study the dynamical and chemical interactions between the neutral and ionospheric constituents of the polar regions. In the polar F region, the seasonal anomaly in ionospheric density is caused by the neutral thermospheric compositional response to the interhemispheric circulation cell near solstice, including the effect of the self-consistent input from geomagnetic heating. A tongue of ionization is carried by convection into the winter polar cap from the vicinity of the dayside (sunlit) polar cusp, while the auroral oval, at F region altitudes, is barely distinct from the surrounding lower-latitude and polar regions. The subauroral trough of the winter hemisphere is caused by stagnation, and is thus dominated by characteristics of the polar convection pattern. A deep plasma trough is cut through the summer (southern) polar cap around 0600 UT, resulting from upwelling by geomagnetic forcing and solar insolation enhancement of molecular nitrogen.

Models for the specific adhesion of cells to cells

Abstract: A theoretical framework is proposed for the analysis of adhesion between cells or of cells to surfaces when the adhesion is mediated by reversible bonds between specific molecules such as antigen and antibody, lectin and carbohydrate, or enzyme and substrate. From a knowledge of the reaction rates for reactants in solution and of their diffusion constants both in solution and on membranes, it is possible to estimate reaction rates for membrane-bound reactants. Two models are developed for predicting the rate of bond formation between cells and are compared with experiments. The force required to separate two cells is shown to be greater than the expected electrical forces between cells, and of the same order of magnitude as the forces required to pull gangliosides and perhaps some integral membrane proteins out of the cell membrane.

A glial progenitor cell that develops in vitro into an astrocyte or an oligodendrocyte depending on culture medium

Abstract: We have identified a cell type in 7-day-old rat optic nerve that differentiates into a fibrous astrocyte if cultured in the presence of fetal calf serum and into an oligodendrocyte if cultured in the absence of serum. In certain culture conditions some of these cells acquire a mixed phenotype, displaying properties of both astrocytes and oligodendrocytes. These observations suggest that fibrous astrocytes and oligodendrocytes develop from a common progenitor cell and provide a striking example of developmental plasticity and environmental influence in the differentiation of CNS glial cells.

Handbook of hydrocolloids.

Abstract: Introduction. Agar. Starch. Gelatin. Carrageenan. Xanthum Gum. Gellan Gum. Gallactomannans. Gum Arabic. Pectins. Milk Proteins. Cellulosis. Tragacanth and Karaya. Xyloglucan. Curdlan. Glucans. Soluble Soybean Polysaccharide. Bacterial Cellulose. Microcrystalline Cellulose. Gums for Coating and Adhesives.Chitosan Hydrogels. Alginates. Frutafit-Inulin. The CRC Emulsifying Biopolymer.