XV. New British Lichens.

Lichens

What are lichens? The term lichen refers to a symbiotic association between a filamentous fungus, the ‘mycobiont’, and at least one photosynthetic organism, the ‘photobiont’, consisting of a micro alga, a cyanobacterium, or both (Figure 1). Although the symbiotic nature of lichens was first revealed in 1867, the development of a lichen thallus is often so integrated (Figure 1D) that they have b...

Xv Xvi

-Monetary policy operates in a different environment than it did a decade ago. Financial market innovations have eroded the distinctions among monetary assets, making the definition of money increasingly arbitrary. Deregulation of interest rates and banking activity is changing the behavior of the monetary aggregates, as banks pay interest on monetary assets and nonbanks offer monetary-like ass...

XV. Geriatrics

Ice XV: a new thermodynamically stable phase of ice.

A new phase of ice, named ice XV, has been identified and its structure determined by neutron diffraction. Ice XV is the hydrogen-ordered counterpart of ice VI and is thermodynamically stable at temperatures below approximately 130 K in the 0.8 to 1.5 GPa pressure range. The regions of stability in the medium pressure range of the phase diagram have thus been finally mapped, with only hydrogen-...

Xv. Neurophysiology*

Resting squid nerve membrane actively extrudes Na+ against a large concentration gradient, while another cation, K + , is concentrated passively within the cell by the Donnan equilibrium. During the passage of an impulse, large transient current flows across the membrane; some K + leaves, some Na + enters, but which ions carry the current at which instant, and how it is turned on and off cannot...