Combinations of rotations and fertilization to maximize crop profits on farms in north-central Iowa (An application of linear programming)

One problem of farmers is to reorganize the use of their resources as new farming techniques are developed. While not a new technique itself, heavy fertilization of grain crops has not been widespread in Iowa. Recent agronomic research and farmer experience indicate, however, that heavy fertilization rates can be profitable under existing price ratios. Fertilization is a relatively simple practice but it can have complex effects on profitable farm organization. One of the major impacts of heavy fertilization is on the rotation system. Grasses and legumes grown in rotation can serve in a complementary capacity to grains.2 As complementary crops, grasses and legumes increase profits to the extent that they (1) provide nitrogen to subsequent grain crops, (2) provide organic matter and improve soil tilth, (3) help control insects and diseases and (4) control erosion. Heavy fertilization substitutes for legumes of the rotation in providing nitrogen for subsequent grain crops. It also may substitute for forages in furnishing organic matter. An acre of heavily fertilized corn, for example, can furnish an equal or a greater weight of plant residues than an acre of clover or alfalfa under particular soil and climatic situations such as in north-central Iowa. Under these conditions, the questions arise: What rotation should be used when corn can be fertilized at heavy rates? Are the profit differences small or great from different crop rotations and fertilization rates? Does the optimum combination of rotations and fertilization rates differ between farms of different size which have varying amounts of operating funds and labor

The Superfluid State of Atomic Li6 in a Magnetic Trap

We report on a study of the superfluid state of spin-polarized atomic Li6 confined in a magnetic trap. Density profiles of this degenerate Fermi gas, and the spatial distribution of the BCS order parameter are calculated in the local density approximation. The critical temperature is determined as a function of the number of particles in the trap. Furthermore we consider the mechanical stability of an interacting two-component Fermi gas, both in the case of attractive and repulsive interatomic interactions. For spin-polarized Li6 we also calculate the decay rate of the gas, and show that within the mechanically stable regime of phase space, the lifetime is long enough to perform experiments on the gas below and above the critical temperature if a bias magnetic field of about 5 T is applied. Moreover, we propose that a measurement of the decay rate of the system might signal the presence of the superfluid state.Comment: 16 pages Revtex including 10 figures, submitted to Phys. Rev.

Rotating ground states of trapped Bose atoms with arbitrary two-body interactions

In a k-dimensional system of weakly interacting Bose atoms trapped by a spherically symmetric and harmonic external potential, an exact expression is obtained for the rotating ground states at a fixed angular momentum. The result is valid for arbitrary interactions obeying minimal physical requirements. Depending on the sign of a modified scattering length, it reduces to either a collective rotation or a condensed vortex state, with no alternative. The ground state can undergo a kind of quantum phase transition when the shape of the interaction potential is smoothly varied.Comment: Talk given at the International Conference on Theoretical Physics (TH2002),Paris, UNESCO, 22-27 July; 11 pages, 3 figures, few typos fixe

A benchmark for microRNA quantification algorithms using the OpenArray platform

miRcompData R package source. The source code for the miRcompData R package, also available at: http://bioconductor.org/packages/miRcompData/ . (GZ 8765 kb

Atom Skimmers and Atom Lasers Utilizing Them

Atom skimmers are devices that act as low-pass velocity filters for atoms in thermal atomic beams. An atom skimmer operating in conjunction with a suitable thermal atomic-beam source (e.g., an oven in which cesium is heated) can serve as a source of slow atoms for a magneto-optical trap or other apparatus in an atomic-physics experiment. Phenomena that are studied in such apparatuses include Bose-Einstein condensation of atomic gases, spectra of trapped atoms, and collisions of slowly moving atoms. An atom skimmer includes a curved, low-thermal-conduction tube that leads from the outlet of a thermal atomic-beam source to the inlet of a magneto-optical trap or other device in which the selected low-velocity atoms are to be used. Permanent rare-earth magnets are placed around the tube in a yoke of high-magnetic-permeability material to establish a quadrupole or octupole magnetic field leading from the source to the trap. The atoms are attracted to the locus of minimum magnetic-field intensity in the middle of the tube, and the gradient of the magnetic field provides centripetal force that guides the atoms around the curve along the axis of the tube. The threshold velocity for guiding is dictated by the gradient of the magnetic field and the radius of curvature of the tube. Atoms moving at lesser velocities are successfully guided; faster atoms strike the tube wall and are lost from the beam

Elastic and inelastic collisions of 6Li in magnetic and optical traps

We use a full coupled channels method to calculate collisional properties of magnetically or optically trapped ultracold 6Li. The magnetic field dependence of the s-wave scattering lengths of several mixtures of hyperfine states are determined, as are the decay rates due to exchange collisions. In one case, we find Feshbach resonances at B=0.08 T and B=1.98 T. We show that the exact coupled channels calculation is well approximated over the entire range of magnetic fields by a simple analytical calculation.Comment: 4 pages revtex including 4 figures, submitted to PR

The Marketization of Religion: Field, Capital, and Consumer Identity

Certain institutions traditionally have had broad socializing influence over their members, providing templates for identity that comprehend all aspects of life from the existential and moral to the mundanely material. Marketization and detraditionalization undermine that socializing role. This study examines the consequences when, for some members, such an institution loses its authority to structure identity. With a hermeneutical method and a perspective grounded in Bourdieu’s theories of fields and capital, this research investigates the experiences of disaffected members of a religious institution and consumption field. Consumers face severe crises of identity and the need to rebuild their self-understandings in an unfamiliar marketplace of identity resources. Unable to remain comfortably in the field of their primary socialization, they are nevertheless bound to it by investments in field-specific capital. In negotiating this dilemma, they demonstrate the inseparability and co-constitutive nature of ideology and consumption.This is the publisher’s final pdf. The published article is copyrighted by the Journal of Consumer Research, Inc. and published by the University of Chicago Press. It can be found at: http://www.jstor.org/page/journal/jconsrese/about.htm

Collisionless collective modes of fermions in magnetic traps

We present a Random-Phase-Approximation formalism for the collective spectrum of two hyperfine species of dilute 40K atoms, magnetically trapped at zero temperature and subjected to a repulsive s-wave interaction between atoms with different spin projections. We examine the density-like and the spin-like oscillation spectra, as well as the transition density profiles created by external multipolar fields. The zero sound spectrum is always fragmented and the density and spin channels become clearly distinguishable if the trapping potentials acting on the species are identical. Although this distinction is lost when these confining fields are different, at selected excitation frequencies the transition densities may display the signature of the channel.Comment: 10 pages, 9 figure

Electron affinity of Li: A state-selective measurement

We have investigated the threshold of photodetachment of Li^- leading to the formation of the residual Li atom in the $2p ^2P$ state. The excited residual atom was selectively photoionized via an intermediate Rydberg state and the resulting Li^+ ion was detected. A collinear laser-ion beam geometry enabled both high resolution and sensitivity to be attained. We have demonstrated the potential of this state selective photodetachment spectroscopic method by improving the accuracy of Li electron affinity measurements an order of magnitude. From a fit to the Wigner law in the threshold region, we obtained a Li electron affinity of 0.618 049(20) eV.Comment: 5 pages,6 figures,22 reference