Microbes require multiple essential elements that they acquire from the environment independently. Here we investigate how microbial stoichiometry and uptake rates depend on the conditions in which they grow. We modify a recent model of growth based on a multinutrient extension of the Droop model to allow a trade-off between ability to acquire two essential resources. In a static analysis, we s...

The mere presence of predators (i.e., predation risk) can alter consumer physiology by restricting food intake and inducing stress, which can ultimately affect prey-mediated ecosystem processes such as nutrient cycling. However, many environmental factors, including conspecific density, can mediate the perception of risk by prey. Prey conspecific density has been defined as a fundamental featur...

The Bayesian deconvolution algorithm described in a preceding paper [Appl. Opt. 43, 5669-5681 (2004)] is applied to measurement of the two-dimensional stoichiometry field in a combustible methane-air mixture by Raman imaging through a spectrograph. Stoichiometry (fuel equivalence ratio) is derived from the number density fields of methane and nitrogen, with a signal-to-noise ratio of approximat...

It has recently been shown that a metal-insulator transition due to disorder occurs in the crystalline state of the GeSb2Te4 phase-change compound. The transition is triggered by the ordering of the vacancies upon thermal annealing. In this work, we investigate the localization properties of the electronic states in selected crystalline (GeTe)x-(Sb2Te3)y compounds with varying GeTe content by l...

We report structurally tuned superconductivity in a K(x)Fe(2-y)Se(2-z)S(z) (0 ≤ z ≤ 2) phase diagram. Superconducting T(c) is suppressed as S is incorporated into the lattice, eventually vanishing at 80% of S. The magnetic and conductivity properties can be related to stoichiometry on a poorly occupied Fe1 site and the local environment of a nearly fully occupied Fe2 site. The decreasing T(c) c...

Selective oxidation of the surface of an ordered alloy requires redistribution of the atomic species in the vicinity of the surface. This process can be understood in terms of the formation and movements of point defects in the compound. On the basis of ab initio density-functional calculation we found both the creation of exchange defects near the NiAl surface and segregation of Ni vacancies t...

We consider a stoichiometric population model of two producers and one consumer. Stoichiometry can be thought of as the tracking of food quality in addition to food quantity. Our model assumes a reduced rate of conversion of biomass from producer to consumer when food quality is low. The model is open for carbon but closed for nutrient. The introduction of the second producer, which competes wi...

Fluorescence antibunching is a well-known technique for determining the number of independent emitters per molecule or molecular complex. It was rarely applied to autofluorescent proteins due to the necessity of collecting large numbers of fluorescence photons from a single molecule, which is usually impossible to achieve with rather photolabile autofluorescent proteins. Here, we measure fluore...

Article history: A range of calcium phosph Received 9 July 2008 Accepted in revised form 5 August 2008 Available online 13 August 2008