Performance evaluation of a second-generation elastic loop mobility system

Tests were conducted to evaluate the mobility performance of a second-generation Elastic Loop Mobility System (ELMS II). Performance on level test lanes and slopes of lunar soil simulant (LSS) and obstacle-surmounting and crevasse-crossing capabilities were investigated. In addition, internal losses and contact pressure distributions were evaluated. To evaluate the soft-soil performance, two basic soil conditions were tested: loose (LSS1) and dense (LSS5). These conditions embrace the spectrum of soil strengths tested during recent studies for NASA related to the mobility performance of the LRV. Data indicated that for the tested range of the various performance parameters, performance was independent of unit load (contact pressure) and ELMS II drum angular velocity, but was influenced by soil strength and ELMS pitch mode. Power requirements were smaller at a given system output for dense soil than for loose soil. The total system output in terms of pull developed or slope-climbing capability was larger for the ELMS II operating in restrained-pitch mode than in free-pitch mode

MARKET FORCES AND CHANGES IN THE PLANT INPUT SUPPLY INDUSTRY

Agribusiness, Input Supply Industry, Fertilizer, Plant Nutrients, Seed, Capital, Market Forces, Structural Change, Porter’s Five Forces, Agribusiness, Q13, L10, L22, M22, L80,

Circular 78

Historically, sales of exotic meats have been limited only by supply. As supply has increased in recent years, national and international exotic game markets have grown rapidly. In the United States, growth has occurred primarily in the restaurant section, although over-the-counter sales have also increased. The Alaskan reindeer industry is exploring the potential of expanding its meat sales as well as antler sales. Meat production increased from 320,000 pounds in 1987 to 432,000 pounds in 1988. This production increase is reflected in a 27 percent increase in dollar value (Alaska Crop and Livestock Reporting Service, 1989). Under current management procedures, potential meat production has been estimated at 500,000 pounds (Pearson and Lewis, 1988). Any future market expansion is likely to occur in urban Alaska and in areas outside the state (Jones, 1988)

A linearized kinetic theory of spin-1/2 particles in magnetized plasmas

We have considered linear kinetic theory including the electron spin properties in a magnetized plasma. The starting point is a mean field Vlasov-like equation, derived from a fully quantum mechanical treatment, where effects from the electron spin precession and the magnetic dipole force is taken into account. The general conductivity tensor is derived, including both the free current contribution, as well as the magnetization current associated with the spin contribution. We conclude the paper with an extensive discussion of the quantum-mechanical boundary where we list parameter conditions that must be satisfied for various quantum effects to be influential.Comment: 11 page

Tests of the Gravitational Inverse-Square Law below the Dark-Energy Length Scale

We conducted three torsion-balance experiments to test the gravitational inverse-square law at separations between 9.53 mm and 55 micrometers, probing distances less than the dark-energy length scale $\lambda_{\rm d}=\sqrt[4]{\hbar c/\rho_{\rm d}}\approx 85 \mu$m. We find with 95% confidence that the inverse-square law holds ($|\alpha| \leq 1$) down to a length scale $\lambda = 56 \mu$m and that an extra dimension must have a size $R \leq 44 \mu$m.Comment: 4 pages, 6 figure

Inflation Assisted by Heterotic Axions

We explore the possibility of obtaining inflation in weakly coupled heterotic string theory, where the model dependent axions are responsible for driving inflation. This model can be considered as a certain extrapolation of $m^{2}\phi^{2}$-inflation, and is an attempt to explicitly realize the so called N-flation proposal in string theory. The instanton generated potential for the axions essentially has two parameters; a natural mass scale $M$ and the string coupling $g_{s}$. For isotropic compactifications leading to of order $\mathcal{O} (10^4)$ axions in the four dimensional spectrum we find that with $(M, g_{s})\simeq(M_{GUT}, 0.5)$ the observed temperature fluctuations in the CMB are correctly reproduced. We assume an initially random distribution for the vevs of the axions. The spectral index, $n_{s}$, is generically more red than for $m^{2}\phi^{2}$-inflation. The greater the vevs, the more red the spectral index becomes. Allowing for a wide range of vevs 55 $e$-foldings from the end of inflation, we find $0.946\lesssim n_{s} \lesssim 0.962$. The tensor-to-scalar ratio, $r$, is more sensitive to the vevs, but typically smaller than in $m^{2}\phi^{2}$-inflation. Furthermore, in the regime where the leading order theory is valid, $r$ is bounded by $r < 0.10$. The spectral index and the tensor-to-scalar ratio are correlated. For example, $n_{s}\simeq 0.951$ corresponds to $r\simeq 0.036$.Comment: 1+21 pages, 2 figures, v2: Typos corrected, v3: Typos, very minor corrections, reference added, to appear in JCA

Canonical Transformations and Path Integral Measures

This paper is a generalization of previous work on the use of classical canonical transformations to evaluate Hamiltonian path integrals for quantum mechanical systems. Relevant aspects of the Hamiltonian path integral and its measure are discussed and used to show that the quantum mechanical version of the classical transformation does not leave the measure of the path integral invariant, instead inducing an anomaly. The relation to operator techniques and ordering problems is discussed, and special attention is paid to incorporation of the initial and final states of the transition element into the boundary conditions of the problem. Classical canonical transformations are developed to render an arbitrary power potential cyclic. The resulting Hamiltonian is analyzed as a quantum system to show its relation to known quantum mechanical results. A perturbative argument is used to suppress ordering related terms in the transformed Hamiltonian in the event that the classical canonical transformation leads to a nonquadratic cyclic Hamiltonian. The associated anomalies are analyzed to yield general methods to evaluate the path integral's prefactor for such systems. The methods are applied to several systems, including linear and quadratic potentials, the velocity-dependent potential, and the time-dependent harmonic oscillator.Comment: 28 pages, LaTe

Interaction between Faraday rotation and Cotton-Mouton effects in polarimetry modeling for NSTX

The evolution of electromagnetic wave polarization is modeled for propagation in the major radial direction in the National Spherical Torus Experiment (NSTX) with retroreflection from the center stack of the vacuum vessel. This modeling illustrates that the Cotton-Mouton effect-elliptization due to the magnetic field perpendicular to the propagation direction-is shown to be strongly weighted to the high-field region of the plasma. An interaction between the Faraday rotation and Cotton-Mouton effects is also clearly identified. Elliptization occurs when the wave polarization direction is neither parallel nor perpendicular to the local transverse magnetic field. Since Faraday rotation modifies the polarization direction during propagation, it must also affect the resultant elliptization. The Cotton-Mouton effect also intrinsically results in rotation of the polarization direction, but this effect is less significant in the plasma conditions modeled. The interaction increases at longer wavelength, and complicates interpretation of polarimetry measurements.Comment: Contributed paper published as part of the Proceedings of the 18th Topical Conference on High-Temperature Plasma Diagnostics, Wildwood, New Jersey, May, 201

Assessment of Alaska reindeer populations and range conditions

Populations of reindeer (Rangifer tarandus) have fluctated greatly since their introduction to Alaska in 1891. In the 1930s, reported numbers exceeded 600 000. Presently, 38 000 reindeer graze 6.2 million ha of rangeland and woodland in Western Alaska (from 66&deg;54'N to 52&deg;07'N latitude). Condition of winter range producing fruticose lichens (Cladina rangiferina, Cladina arbuscula, Cladina stellaris, Cetraria cucullata, Cetraria islandica) is of major concern. Monitoring programs have been established for vegetation, fire, reindeer and wildlife. Reindeer have overgrazed lichen resources on some Bering Sea Islands. Wildfires have had the greatest impact on lichen range depletion on the mainland. Overgrazing has been a problem in localized areas. Moose (Alces alces) and muskox (Ovibos moschatus) rarely contribute to major lichen depletion. 60-80% of the mainland and 5-30% of most island winter lichen ranges are presently estimated to be in good to excellent ecological condition. Procedures for assessing condition of the lichen ranges are being further refined

The steady flow between reservoirs with different density and level through a contraction

This paper presents a complete analytical solution of steady gravity flow between two reservoirs connected by a channel of slowly varying breadth and containing fluids of different densities and levels. The hydrostatic approximation is used and dissipation is neglected. It is shown that seven different regimes are possible depending on the value of the parameter δ = γ/ε, which is the ratio of relative lighter and denser reservoir level difference, γ, to positive relative density difference, ε. The exact solution of the problem is obtained for all these regimes. If the level of the heavier fluid reservoir is higher than the level of lighter fluid reservoir, δ ≤ 0, then the denser fluid plunges under the lighter motionless fluid. If δ ≥ 1, the lighter fluid runs up on a wedge of the motionless denser fluid. If 0 \u3c δ \u3c 1, two-directional exchange flow occurs. The exact analytical expressions for layer discharges for the entire range of the parameters ε and δ are found and discussed. Wood\u27s (1970) experimental data with nonsmall ε are in good agreement with the theory. When ε → 0 an exchange regime exists as long as γ → 0 to keep their ratio between 0 and 1, 1 \u3e γ/ε \u3e 0. At this limit the existence of an exchange flow and the solution depend only on the ratio γ/ε, not the values of γ and ε individually, and the Boussinesq approximation can be used. Some examples of application of the theory to prediction of mass and volume transport through a contraction for steady and quasi-steady flows are given