Mechanical design of NASA Ames Research Center vertical motion simulator

NASA has designed and is constructing a new flight simulator with large vertical travel. Several aspects of the mechanical design of this Vertical Motion Simulator (VMS) are discussed, including the multiple rack and pinion vertical drive, a pneumatic equilibration system, and the friction-damped rigid link catenaries used as cable supports

Farm Sprayers for 2,4-D

Want to spray your own weeds? Homemade spray outfits can do the job. Lots of Iowa farmers are using them cheaply and effectively

The Control of Poison Ivy

Poison ivy (Rhus radicans L.) is a woody perennial, reproducing by seeds and creeping root stalks. It is found in rocky fields, pastures, fence rows, on roadsides, railroad embankments, under telephone lines, and in rich alluvial woodlands. Poison ivy is native in Iowa and widespread throughout the United States and Canada. Earliest mention of poison ivy was made by Captain John Smith in 1609. J. P. Cornut described the plant in his work on Canadian plants in 1635. It has been shown that as many as 26 different kinds of birds arc responsible for the wide dissemination of poison ivy

On the influence of a Coulomb-like potential induced by the Lorentz symmetry breaking effects on the Harmonic Oscillator

In this work, we obtain bound states for a nonrelativistic spin-half neutral particle under the influence of a Coulomb-like potential induced by the Lorentz symmetry breaking effects. We present a new possible scenario of studying the Lorentz symmetry breaking effects on a nonrelativistic quantum system defined by a fixed space-like vector field parallel to the radial direction interacting with a uniform magnetic field along the z-axis. Furthermore, we also discuss the influence of a Coulomb-like potential induced by Lorentz symmetry violation effects on the two-dimensional harmonic oscillator.Comment: 14 pages, no figure, this work has been accepted for publication in The European Physical Journal Plu

Another Year of 2,4-D

About a million acres of corn and 500,000 acres of small grain and flax were sprayed with 2,4-D in Iowa last season. County extension directors report an estimated 62,000 miles of fencerows were so treated. Chemical manufacturers sold between 500,000 and 800,000 pounds of actual 2,4-D last year

Resolution of the Klein Paradox

We present a resolution of the Klein paradox within the framework of one-particle relativistic quantum mechanics. Not only reflection becomes total but the vacuum remains neutral as well. This is accomplished by replacing the pair production process with virtual negative energy "incidence" within the barrier in a similar manner to what is done with image charges in electrostatic and virtual sources in optics.Comment: 9 pages, 8 figure

Disentangling source of moisture driving glacier dynamics and identification of 8.2 ka event: evidence from pore water isotopes, Western Himalaya

Two atmospheric circulation patterns, the Indian Summer Monsoon (ISM) and mid-latitude Westerlies control precipitation and thus glacier variability in the Himalaya. However, the role of the ISM and westerlies in controlling climate and thus past glacier variability in the Himalaya is poorly understood because of the paucity of the ice core records. In this article, we present a new Holocene paleorecord disentangling the presence of the ISM and mid-latitude westerlies and their effect on glacier fluctuations during the Holocene. Our new record is based on high-resolution multi-proxy analyses (δ18Oporewater, deuterium-excess, grain size analysis, permeability, and environmental magnetism) of lake sediments retrieved from Chandratal Lake, Western Himalaya. Our study provides new evidence that improves the current understanding of the forcing factor behind glacier advances and retreat in the Western Himalaya and identifies the 8.2 ka cold event using the aforementioned proxies. The results indicate that the ISM dominated precipitation ~ 21% of the time, whereas the mid-latitude westerlies dominated precipitation ~ 79% of the time during the last 11 ka cal BP. This is the first study that portrays the moisture sources by using the above proxies from the Himalayan region as an alternative of ice core records.publishedVersio

Magnetic ground state and magnon-phonon interaction in multiferroic h-YMnO3_3

Inelastic neutron scattering has been used to study the magneto-elastic excitations in the multiferroic manganite hexagonal YMnO$_3$. An avoided crossing is found between magnon and phonon modes close to the Brillouin zone boundary in the $(a,b)$-plane. Neutron polarization analysis reveals that this mode has mixed magnon-phonon character. An external magnetic field along the $c$-axis is observed to cause a linear field-induced splitting of one of the spin wave branches. A theoretical description is performed, using a Heisenberg model of localized spins, acoustic phonon modes and a magneto-elastic coupling via the single-ion magnetostriction. The model quantitatively reproduces the dispersion and intensities of all modes in the full Brillouin zone, describes the observed magnon-phonon hybridized modes, and quantifies the magneto-elastic coupling. The combined information, including the field-induced magnon splitting, allows us to exclude several of the earlier proposed models and point to the correct magnetic ground state symmetry, and provides an effective dynamic model relevant for the multiferroic hexagonal manganites.Comment: 12 pages, 10 figure

Seed Retention of Some Prairie Plants

There are still a number of native prairie areas in Iowa. One of these outstanding tracts belongs to the Steel family of Cherokee, Iowa. It consists of about half a section located in Cedar Township in Cherokee county (N. 1/2 Sec. 16) one and a half miles northwest of the town of Larabee. The area has never been plowed: as a matter of fact, it has never been fenced. The flora of this area, like most of the other generally treeless areas of the state consist largely of perennial plants of a distinctly xerophytic type (1.3.4.5). The Graminae are the most numerous, although exceeded in generic numbers by the Compositae, with the Leguminosae in third place. In the more highly developed soils, with better drainage and increased organic content, the dominant grasses include porcupine grass (Stipa spartea Trin.), little blue stem (Andropogon scoparius Michx.), Prairie drop seed (Sporobulus heterolepsis Gray), and numerous sub-dominant plants such as species of sunflower (Helianthus), golden rod (Solidago), blazing star (Liatris), tickseed (Coreopsis), and prairie clover (Petalostemum). Exposure to evaporation, as determined by temperature, wind and topography, is the primary cause of the treelessness according to Shimek (3.4)