Contour farming for soil and water conservation

In order to keep Iowa soils from becoming less fertile and from being washed away, it is necessary that every farmer develop and carry out a program of soil and moisture conservation for his farm. This program need not be complicated. Any Iowa farmer can, by following practical methods, keep his soil fertile and in place. Every acre of a farm should be planned to produce its maximum income in whatever crop it is adapted to produce. Soils on level areas can be kept fertile by proper crop rotation and necessary soil treatments. Rolling land should be handled the same way except that as it becomes steeper other practices must be adopted to keep the soil from washing away. Some lands must remain in pasture, while those less fertile areas which are becoming eroded should be planted to trees

Spontaneous Emission Spectra and Quantum Light-Matter Interactions from a Strongly-Coupled Quantum Dot Metal-Nanoparticle System

We investigate the quantum optical properties of a single photon emitter coupled to a finite-size metal nanoparticle using a photon Green function technique that rigorously quantizes the electromagnetic fields. We first obtain pronounced Purcell factors and photonic Lamb shifts for both a 7-nm and 20-nm radius metal nanoparticle, without adopting a dipole approximation. We then consider a quantum-dot photon emitter positioned sufficiently near to the metal nanoparticle so that the strong coupling regime is possible. Accounting for non-dipole interactions, quenching, and photon transport from the dot to the detector, we demonstrate that the strong coupling regime should be observable in the far-field spontaneous emission spectrum, even at room temperature. The emission spectra show that the usual vacuum Rabi doublet becomes a rich spectral triplet or quartet with two of the four peaks anticrossing, which survives in spite of significant non-radiative decays. We discuss the emitted light spectrum and the effects of quenching for two different dipole polarizations.Comment: 5 figure

Transformation of Quartz to Tridymite in the Presence of Binary Silicate Liquids

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/66429/1/j.1151-2916.1967.tb15146.x.pd

The stabilizing role of itinerant ferromagnetism in inter-granular cohesion in iron

We present a simple, general energy functional for ferromagnetic materials based upon a local spin density extension to the Stoner theory of itinerant ferromagnetism. The functional reproduces well available ab initio results and experimental interfacial energies for grain boundaries in iron. The model shows that inter-granular cohesion along symmetric tilt boundaries in iron is dependent upon strong magnetic structure at the interface, illuminates the mechanisms underlying this structure, and provides a simple explanation for relaxation of the atomic structure at these boundaries.Comment: In review at Phys. Rev. Lett. Submitted 23 September 1997; revised 16 March 199