276 research outputs found
A Current Analysis of the Usury Laws a National View
This Article explains the history of usury laws, elements of the law, exemptions, special cases, and penalties
Temperature equilibration in a fully ionized plasma: electron-ion mass ratio effects
Brown, Preston, and Singleton (BPS) produced an analytic calculation for
energy exchange processes for a weakly to moderately coupled plasma: the
electron-ion temperature equilibration rate and the charged particle stopping
power. These precise calculations are accurate to leading and next-to-leading
order in the plasma coupling parameter, and to all orders for two-body quantum
scattering within the plasma. Classical molecular dynamics can provide another
approach that can be rigorously implemented. It is therefore useful to compare
the predictions from these two methods, particularly since the former is
theoretically based and the latter numerically. An agreement would provide both
confidence in our theoretical machinery and in the reliability of the computer
simulations. The comparisons can be made cleanly in the purely classical
regime, thereby avoiding the arbitrariness associated with constructing
effective potentials to mock up quantum effects. We present here the classical
limit of the general result for the temperature equilibration rate presented in
BPS. We examine the validity of the m_electron/m_ion --> 0 limit used in BPS to
obtain a very simple analytic evaluation of the long-distance, collective
effects in the background plasma.Comment: 14 pages, 4 figures, small change in titl
Influence of Dibble Shape and Depth on the Germination and Seedling Establishment of Burley Tobacco in the Float System
Direct seeding of pelleted tobacco seed into the float transplant system has become common in Kentucky. Direct seeding reduces labor compared to the plug and transfer method, but it increases the risk involved and requires more management by the producer. Uniform germination, and ultimately a high percentage of useable transplants are the keys to success with direct seeding
Root Growth and Development of Float Tobacco Transplants Before and After Transplanting
In the production of float tobacco transplants, the seedling produces at least two different kinds of roots. The “media” roots are those that grow in the soilless medium within the float tray cell. They have a normal branched appearance similar to roots produced on soil-bed grown transplants. The “water” roots grow through the soilless medium in tray cells and into the nutrient solution below the float tray. They tend to be very fragile and less branched than roots growing in the soilless medium. In removal of seedlings from tray cells during transplanting, “water” roots are usually badly damaged or destroyed, which could affect establishment of transplants in the field since the most critical period in the development of tobacco plants occurs immediately after transplanting. When these young plants are removed from the protective environment of the float bed system and are subjected to radically different and sometimes adverse field conditions, stress on the juvenile plants is created. Field establishment of these young plants is dependent upon growth or new formation of the “media” and “water” roots.
To maximize establishment of transplants, it is important to know how the \u27\u27water roots and the media roots develop in the float system and their contribution to transplant establishment during the first few weeks after transplanting. The objectives of this study were: 1) to characterize the growth of media and \u27\u27water roots on tobacco seedlings in the float system, and 2) to assess tobacco transplant growth with or without \u27\u27water\u27\u27 roots, at two and four weeks after transplanting
Land Use and Operational Controls in the Planned Development
This Article takes a look at the historical development of land use controls and planned development; the internal organization and operational of a home owners\u27 association; and legal considerations in establishing effective and viable covenants, conditions, and restrictions
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An approach to thermal convection problems in geophysics with application to the earth's mantle and ground water systems
Two thermal convection problems of geophysical interest are
examined, theoretically. First, convection in the earth's mantle is
treated on the basis of a one-dimensional 'strip model'. This model
results from further simplification of the well known 'Rayleigh model'.
For homogeneous, Newtonian fluids, the strip model yields results
similar to those obtained by the Rayleigh method.
The strip model is used to determine the critical Rayleigh
number for convection in an internally heated two-phase fluid. The
critical number depends on the parameters of the phase transition,
the physical properties of the fluid, and the depth of the fluid layer.
Depending on these factors, a univariant phase transformation may
either enhance or hinder convective instability. For the olivine-spinel
and spinel-oxides transitions in (MgFe)₂SiO₄ which are thought
to take place in the upper mantle, it is shown that the critical Rayleigh number is altered only slightly from the critical number for convection
in a fluid with one phase. This result holds both for convection in the
entire mantle or convection restricted to the upper mantle. Hence the
phase changes are of minor importance regarding the existence of
mantle convection in general.
A method for estimating the order of magnitude of the displacement
of the phase surface as a function of Rayleigh number is outlined
for a fluid with only one phase transition. The strip model is also
used to treat convection in non-Newtonian fluids obeying a power law
rheological equation. If the mantle is governed by a flow law of this
type, it appears that convection can take place. Lastly, the procedure
for applying the strip model to fluids with variable viscosity and
thermal conductivity is outlined.
The second convection problem concerns some aspects of convection
of fluids in thin vertical fractures in the crust. A steady
state model is developed to estimate the magnitude of the mass flow
as a function of fracture thickness. It is shown that fractures of the
order of a millimeter thick or greater can carry a measurable convective
flow. A time dependent model is used to estimate the rate of
decay of the mass flow with time. The results indicate that in fractures
of the order of a centimeter thick, a measurable decrease of
the mass flow takes place after a period of the order of a day. This
rapid decay rate suggests that the principal effect of sea water convection in extensive fracture systems which are expected on mid-ocean
ridge crests is to cool a volume of crustal rock in the vicinity
of the fractures. Circulation of sea water in vertical fractures in the
upper crust may provide an explanation of 1) the relatively low conductive
heat flow measured at some locations on ocean ridge axes
and 2) the very 'noisy' data obtained in the axial zone
Effect of Seed Pellet Modification on Spiral Root Formation of Tobacco Seedlings
Tobacco seeds are often pelleted to facilitate precision seeding into float trays. Pelleting consists of the application of solid particles, such as clay, to seeds with a binder in a coating pan or tumbling drum to form spherically shaped dispersal units. One of the several advantages of pelleting is to provide seeds with a vastly enlarged bulk size to ensure proper placement of the seed at the surface of the growing medium
NH11B-1726: FrankenRaven: A New Platform for Remote Sensing
Small, modular aircraft are an emerging technology with a goal to maximize flexibility and enable multi-mission support. This reports the progress of an unmanned aerial system (UAS) project conducted at the NASA Ames Research Center (ARC) in 2016. This interdisciplinary effort builds upon the success of the 2014 FrankenEye project to apply rapid prototyping techniques to UAS, to develop a variety of platforms to host remote sensing instruments. In 2016, ARC received AeroVironment RQ-11A and RQ-11B Raven UAS from the US Department of the Interior, Office of Aviation Services. These aircraft have electric propulsion, a wingspan of roughly 1.3m, and have demonstrated reliability in challenging environments. The Raven airframe is an ideal foundation to construct more complex aircraft, and student interns using 3D printing were able to graft multiple Raven wings and fuselages into FrankenRaven aircraft. Aeronautical analysis shows that the new configuration has enhanced flight time, payload capacity, and distance compared to the original Raven. The FrankenRaven avionics architecture replaces the mil-spec avionics with COTS technology based upon the 3DR Pixhawk PX4 autopilot with a safety multiplexer for failsafe handoff to 2.4 GHz RC control and 915 MHz telemetry. This project demonstrates how design reuse, rapid prototyping, and modular subcomponents can be leveraged into flexible airborne platforms that can host a variety of remote sensing payloads and even multiple payloads. Modularity advances a new paradigm: mass-customization of aircraft around given payload(s). Multi-fuselage designs are currently under development to host a wide variety of payloads including a zenith-pointing spectrometer, a magnetometer, a multi-spectral camera, and a RGB camera. After airworthiness certification, flight readiness review, and test flights are performed at Crows Landing airfield in central California, field data will be taken at Kilauea volcano in Hawaii and other locations
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Extent of the microbial biosphere in the oceanic crust
We estimate the depth of the 120°C isotherm by constructing crustal thermal gradients based on theoretical and observed conductive heat flux as a function of lithospheric age. We chose the 120°C isotherm because it is close to the upper limit for prokaryotic life, and therefore, the isotherm approximates the maximum depth at which life can persist in the ocean crust. The depth of the potential microbial biosphere increases with lithospheric age from approximately 0.5 to 1 km for 1 Ma lithosphere to as much as 5 km at a subduction age of 180 Ma. We use global models of oceanic plate creation to estimate the volume of crust occupied by the biosphere today and throughout geologic time. Presently, the volume of the ocean crust that is capable of containing life is similar to the volume of the oceans (∼1018 m3). Depending on the model used for the growth of continental crust, the volume of rock available to house the subsurface biosphere may have remained constant or doubled since the Archean. Although the thermal models presented here provide estimates for the potential depth and volume of rock in which microbes may live, the biomass in this volume is not well constrained. Using a previously published model, the prokaryotic biomass in the igneous ocean crust is estimated to exceed that in all aquatic and soil environments and is similar to that in the continental subsurface and in marine sediment. Most of the crustal biomass beneath the sediments is likely contained within the extrusive layer, and this has probably been the case since microbes first colonized the oceanic crust in the Archean.Keywords: Microbial biosphere, Ocean crust, Thermal structur
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