Reaction of the chick to one atmosphere of oxygen

Experiment to determine chicken reaction to 100 percent oxygen at atmospheric pressur

Embryo development and chick growth in a helium - oxygen atmosphere

Embryo development and chick growth in helium- oxygen atmospher

Symmetry based determination of space-time functions in nonequilibrium growth processes

We study the space-time correlation and response functions in nonequilibrium growth processes described by linear stochastic Langevin equations. Exploiting exclusively the existence of space and time dependent symmetries of the noiseless part of these equations, we derive expressions for the universal scaling functions of two-time quantities which are found to agree with the exact expressions obtained from the stochastic equations of motion. The usefulness of the space-time functions is illustrated through the investigation of two atomistic growth models, the Family model and the restricted Family model, which are shown to belong to a unique universality class in 1+1 and in 2+1 space dimensions. This corrects earlier studies which claimed that in 2+1 dimensions the two models belong to different universality classes.Comment: 18 pages, three figures included, submitted to Phys. Rev.

Ab initio determination of an extended Heisenberg Hamiltonian in CuO2 layers

Accurate ab initio calculations on embedded Cu_4O_{12} square clusters, fragments of the La_2CuO_4 lattice, confirm a value of the nearest neighbor antiferromagnetic coupling (J=124 meV) previously obtained from ab initio calculations on bicentric clusters and in good agreement with experiment. These calculations predict non negligible antiferromagnetic second-neighbor interaction (J'=6.5 meV) and four-spin cyclic exchange (K=14 meV), which may affect the thermodynamic and spectroscopic properties of these materials. The dependence of the magnetic coupling on local lattice distortions has also been investigated. Among them the best candidate to induce a spin-phonon effect seems to be the movement of the Cu atoms, changing the Cu-Cu distance, for which the variation of the nearest neighbor magnetic coupling with the Cu-O distance is {\Delta J}/{\Delta d_{Cu-O}}\sim 1700 cm^{-1} A^{-1}.Comment: 11 pages, 5 figures, submitted to Phys. Rev.

Shaping an ultracold atomic soliton in a travelling wave laser beam

An ultracold wave packet of bosonic atoms loaded into a travelling laser wave may form a many-atom soliton.This is disturbed by a homogeneous force field, for example by the inevitable gravitation. The wave packet is accelerated and therefore the laser frequency appears to be chirped in the rest frame of the atoms. We derive the effective nonlinear Schr\"odinger equation. It shows a time dependent nonlinearity coefficient which amounts to a damping or antidamping, respectively. The accelerated packet solution remains a soliton which changes its shape adiabatically. Similarly, an active shaping can be obtained in the force-free case by chirping the laser frequency thus representing a way of coherent control of the soliton form. The experimental consequences are discussed.Comment: 5 pages, Latex, to published in Europhys. Let

Origin and Developmental History of Minnesota Lakes

ABSTRACT-Most lakes in Minnesota owe their origin directly or indirectly to glacial deposition or erosion 10,000 to 20,000 years ago. The lakes\u27 shapes have since been modified by waves and currents near the shores and by the deposition of sediment off-shore-principally the sediment produced by growth of algae and other organisms. This sediment is a receptacle for pollen grains blown into the lake from the surrounding vegetation, and the stratigraphic succession of pollen grains records the postglacial vegetational and thus climatic history of the area. The sediment also preserves the fossils of microorganisms that reveal by their chemical composition the record of past changes in salinity, which in tum is related to water levels and thus to climate. Knowledge of the natural prehistoric processes in lakes and landscapes as recorded in lake sediments provide a perspective for evaluating the effects of modem land use and pollution on the chemical and biological processes in lakes, and it may assist in plans for improving their water quality and management