Although humanity depends on the continued, aggregate functioning of natural ecosystems, few studies have explored the impact of community structure on the stability of aggregate community properties. Here we derive the stability of the aggregate property of community biomass as a function of species' competition coefficients for a two-species model. The model predicts that the stability of com...

It is well known that the permeability and density of an aggregate decreases with its size, affecting its settling velocity and coagulation rate (rate of particle capture) with other particles. This change in aggregate density with size can be described by fractal scaling relationships. Two distinctly different fractal scaling approaches, however, have been used to describe aggregate permeabili...

We present a simple theoretical framework that integrates the notion of the natural or neutral interest rate, liquidity preference theory, and the monetary policy practice by modern central banks. We claim that this theory explains the conditions under which an economy will experience an aggregate demand deficiency problem within a modern institutional setting. Contrary to the predictions of th...

I construct a model of an asset market subject to search frictions, in an environment where both investment and asset liquidity are determined endogenously. This provides a natural framework to analyze the interaction between capital reallocation and liquidity in response to aggregate shocks, which I assess quantitatively. The search model of capital reallocation exhibits strong internal propag...

We describe an implemented system that anticipates user instructions in a collaborative construction task in virtual reality. The functionality of the system is embodied by an anthropomorphic interface agent and enables the usage of functional names for pieces of an uncompleted target aggregate in natural language instructions. Based on an internal model of the construction state and salience r...

External uniqueness is a novel form of unique pointers that fit more natural with object-oriented programming. External uniqueness enforces the structural property that a unique pointer is a dominating node to the aggregate it references—there may be no other pointer from outside the aggregate to objects in it in the rest of the system. This paper completes previous work by the authors (Clarke ...

This paper presents authors’ own tests of the impact strength concrete. The were carried out using a pendulum ballistic hammer, two types concrete with natural aggregate: pebble (river) gravel aggregate and medium-grained crushed granite aggregate. concretes tested on cubic specimens varying W/C ratios (0.40; 0.45; 0.50; 0.55). surface roughness grains in aggregates used for was measured profil...