When is Sustainability a Liability, and When Is It an Asset? Quality Inferences for Core and Peripheral Attributes

When every $P$-flat ideal is flat

In this paper‎, ‎we study the class of rings in which every $P$-flat‎ ‎ideal is flat and which will be called $PFF$-rings‎. ‎In particular‎, ‎Von Neumann regular rings‎, ‎hereditary rings‎, ‎semi-hereditary ring‎, ‎PID and arithmetical rings are examples of $PFF$-rings‎. ‎In the context domain‎, ‎this notion coincide with‎ ‎Pr"{u}fer domain‎. ‎We provide necessary and sufficient conditions for‎...

When is it an osteoclast?

Using acid phosphatase as a marker, osteoclasts were examined from single sections of undemineralised iliac crest biopsies from patients with renal failure and from normal controls. Eighty one per cent of the cells from controls and 56% of the cells from patients with renal failure appeared to be non-nucleated or mononucleated. Serial sections showed, however, that 73% of the control cells were...

When is it an osteoclast?

When Senescence Is Optimal and When It Is Not

A simple model is developed that captures the main features of life reproduction, growth and maintenance. These features are determined by a single state variable, vitality. The resulting optimal life-history strategies are classified with respect to the course of their characteristic age-trajectory of mortality. It is shown that the range of optimal life histories is wide. The main factors tha...

Optimal Growth when Environmental Quality is a Research Asset

If environmental quality positively a ects the productivity of labor in R&D and pollution is caused by the use of a non-renewable resource, it is socially optimal to postpone extraction and to intertemporally adjust R&D e ort.