Viewing the ways a living cell can organize its metabolism as the phase space of a physical system, regulation can be seen as the ability to reduce the entropy of that space by selecting specific cellular configurations that are, in some sense, optimal. Here we quantify the amount of regulation required to control a cell's growth rate by a maximum-entropy approach to the space of underlying met...

A model for cometabolism is verified experimentally for a defined methanotrophic mixed culture. The model includes the effects of cell growth, endogenous cell decay, product toxicity, and competitive inhibition with the assumption that cometabolic transformation rates are enhanced by reducing power obtained from oxidation of growth substrates. A theoretical transformation yield is used to quant...

After defoliation by herbivores, some plants exhibit enhanced rates of photosynthesis and growth that enable them to compensate for lost tissue, thus maintaining their fitness relative to competing, undefoliated plants. Our aim was to determine whether compensatory photosynthesis and growth would be altered by increasing concentrations of atmospheric CO2 , Defoliation of developing leaflets on ...

Changes in climate and atmospheric CO2 and nitrogen (N) over the last several decades have induced significant effects on forest carbon (C) cycling. However, contributions of individual factors are largely unknown because of the lack of long observational data and the undifferentiating between intrinsic factors and external forces in current ecosystem models. Using over four decades (1956-2001)...

Organs form with remarkably consistent sizes and shapes during development, whereas a high variability in growth is observed at the cell level. Given this contrast, it is unclear how such consistency in organ scale can emerge from cellular behavior. Here, we examine an intermediate scale, the growth of clones of cells in Arabidopsis sepals. Each clone consists of the progeny of a single progeni...

The growth of loudness of a tone burst following an intense forward masker was measured as a function of the tone level. The level of the forward-masked tone was adjusted to balance the loudness of a standard tone presented without a forward masker, using a 2AFC, double-staircase, tracking procedure. The forward masker was a 90-dB SPL, 100-ms, 1000-Hz pure tone. The standard tone and the masked...

Using stochastic conformal mapping techniques we study the patterns emerging from Laplacian growth with a power-law decaying threshold for growth R(-gamma)(N) (where R(N) is the radius of the N-particle cluster). For gamma>1 the growth pattern is in the same universality class as diffusion limited aggregation (DLA), while for gamma<1 the resulting patterns have a lower fractal dimension D(gamma...

The concentration of specific alloantibody in purified mouse immunoglobulin preparations was determined. When passively transferred in adequate doses, IgM, IgG1, and IgG2 antibodies all induced tumor enhancement in allogeneic hosts. IgM and IgG2 antibodies in high concentration led to inhibition of tumor growth. IgM and either IgG1 or IgG2 had additive effects on tumor enhancement. IgG1, but no...

bermudagrass [cynodon dactylon (l.) pers.] is a perennial grass and has been long used as a medicinal herb in iranian traditional medicine to treat varied ailments. different parts of bermudagrass such as leaves, stolons, rhizomes and culms are rich sources of metabolites such as proteins, carbohydrates, mineral constituents, β-sitosterol, flavonoids, alkaloids, glycosides and triterpenoides. g...