Caldwell model

Prior to the Voyager 1 encounter, Danielson eta/. (1973) and Caldwell (1977) had developed a simple model for Titan s atmospheric thermal structure and haze that fit the ground-based far infrared data available at that time. In this model, an isothermal 160 K atmosphere containing a haze with an emissivity proportional to wavenumber overlay a surface of 78 K. The observed 1304 cm V4-band of CH4 and the 821 cm V9-band of C2H6 were adequately reproduced, as was the continuum between 300 and 600 cm (see Fig. 6.4.1a). Based on the Voyager 1 occultation temperature profile, it was natural to assume that the surface in the Danielson-Caldwell model corresponded to opaque methane clouds near the tropopause, and... 

The model concerning wound healing occurs in two phases (1) pro-inflammatory responses (Glaser and Kiecolt-Glaser 2005 Moore 1999 Tidball 2005 Whelan et al. 2005) which are needed to ensure adequate clearance of pathogen at the site of tissue injury, as well as, (2) re-epithelialization and neovascularization events (Frantz et al. 2005 Moore 1999 Naldini and Carraro 2005 Olah and Caldwell 2003 Whelan et al. 2005) to ensure proper wound closure. It is important to note that the resolution of pathogen clearance is essential in order for the wound closure processes to take place (Robson 1997). 

R. B. Jackson and M. M. Caldwell, Integrating resource heterogeneity and plant plasticity modelling nitrate and phosphate uptake in a patchy soil environment. J. Ecol. 84 891 (1996). 

R. J. Ryel and M. M. Caldwell, Nutrient acquisition from soils with patchy nutrient di.stributions as a.ssessed with simulation models. Ecology 79 2725 (1998). 

Cieplak, P., Caldwell, J. W., Kollman, P. A., Molecular mechanical models for organic and biological systems going beyond the atom centered two body additive approximation aqueous solution free energies of methanol and IV-methyl acetamide, nucleic acid base, and amide hydrogen bonding and chloroform/water partition coefficients of the nucleic acid bases, J. Comput. Chem. 2001, 22, 1048-1057... 

S. A. Hotchkiss, P. Hewitt, J. Caldwell, W. L. Chen, and R. R. Rowe. Percutaneous absorption of nicotinic acid, phenol, benzoic acid and triclopyr butoxyethyl ester through rat and human skin in vitro Further validation of an in vitro model by comparison with in vivo data. Food Chern. Toxicol. 30 891-899 (1992). 

S. A. Hotchkiss, M. A. Chidgey, S. Rose, and J. Caldwell. Percutaneous absorption of benzyl acetate through rat skin in vitro. I. Validation of an in vitro model against in vivo data. Food Chem. Toxicol. 28 443-447 (1990). 

Caldwell, E.S. and Steelink, C. (1969). Phenoxy radical intermediates in the enzymatic degradation of lignin model compounds. Biochimica et Biophysica Acta, 184,420-431. 

Studies of proton transfers involving small ions with localized charge have shown that these reactions may proceed indeed with rate constants close to or even slightly larger than the collision rate constants predicted by the ADO theory (Mackay et al., 1976). However, rate-constant measurements of proton-transfer reactions between delocalized anions (Farneth and Brau-man, 1976) and sterically hindered pyridine bases (Jasinski and Brauman, 1980) and of SN2 displacement reactions (Olmstead and Brauman, 1977 Pellerite and Brauman, 1980 Pellerite and Brauman, 1983 Caldwell et al., 1984 for a review see Riveros et al., 1985) have shown that the rate constants can span the range from almost collision controlled values down to ones too slow to be observed. For these reactions the wide variation in rate constants has been explained on the basis of a double potential-well model which for a hypothetical SN2 substitution is schematically shown in Fig. 4. 

Caldwell, G.A., Naider, F., and Becker, J.M. (1995). Fungal lipopeptide mating pheromones a model system for the study of protein prenylation. Microbiol Rev 59 406-422. 

Another system in this class of mechanisms that was also modeled mathematically is the technically important Fischer-Tropsch process on Fe catalysts investigated by Caldwell (217,218). Oscillation had been previously observed in this system by Tsotsis and co-workers (279). Caldwell reduced the mechanism of the Fischer-Tropsch reaction to three reactions ... 

The catalytically active phase was assumed to be exclusively a-Fe, and Fe304 was assumed not to be active for the Fischer-Tropsch reaction. Kinetic parameters for the simulations were obtained independently in separate oxidation/reduction studies. Balancing the oxidation and reduction rates for the CO/CO2 and the H2/H2O systems independently and describing the rate of synthesis in Fischer-Tropsch reactions by a standard expression, Caldwell could predict the oscillations with a simplified model for a tubular reactor fairly well. 

A qualitative model for predicting the height of the barrier as a function of the location of the avoided crossing on the reaction coordinate was proposed by Caldwell (1980). It is based on an estimate of the crossing between the correla ion line of the doiihlv excited confipuraiion D and the ground... 

The model used in the above studies ignores the departure from the bulk density of the adsorbate brought about by the interaction of the two interfaces. Li and Caldwell s article addresses this issue by introducing a three-component model consisting of a core particle, a flexible macromolecular substance with affinity toward the particle, and a solvation shell (see Fig. lb). 

Temporal variations over short time scales have also been accounted for in this model. They are a result of the diurnal pattern of water uptake which peaks at midday and is zero at night. At night, however, the direction of water fluxes can revert, this hydraulic lift being responsible for water efflux from roots at the top of the root system, especially from those roots growing in the topsoil when it dries out (Caldwell et al., 1998). 

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