36,718 research outputs found
Chemistry of the Spring Waters of the Ouachita Mountains Excluding Hot Springs, Arkansas
This report is based on the chemical analysis of the waters from 93 springs and 9 wells. Springs, when free from metal plumbing, provide an uncontaminated source of the ground water and it was desired to obtain water uncontaminated with metals. A few wells were added to the list, usually because of their unique location in the sampling grid
Nutrients and Acid in the Rain and Dry Fallout at Fayetteville, Arkansas (1980-1982)
Wet and dry fallout at Fayetteville, Arkansas have been collected separately and analyzed since April, 1980. The precipitation-weighted-average pH for two yearly periods of rainfall were 4.72 (6/80-5/81) and 4.75 (6/81-5/82). This corresponds to a concentration of the acid ion, H+, of about 18 parts per billion (ppb). Pure water in equilibrium with the CO2 of the air would have a pH of 5.65 (2.2 ppb of H+). The range of pH during this two year period was 3.86-7.74(140-0 ppb H+) for the rainfall. Aqueous extracts of the dry fallout were always in the 6.75-7.87 pH range, i.e., neutral to slightly alkaline. The slight amount of acidity in the Fayetteville rainfall should be easily neutralized by dry fallout and soil. Ammonium bisulfate, NH4HSO4, is the major acidic chemical in the rains. Sulfur tends to increase in winter months presumably due to the greater use of fossil fuels. Northern rains have the most acidity. Wet and dry fallout add significant amounts of nutrients to the local soils with 25-87% of the total flux being dry fallout. A. major contributor are dust storms which bring in soil from adjacent states. Iron and zinc were the most prevalent heavy metals in the wet fallout. Their concentrations were very low averaging less than 10 ppb for Fe and 15 ppb for Zn. Northernly and southernly rains had the most Fe and Zn and correspond to directions in which there are smelters
Prior Day Effect in Forecasting Daily Natural Gas Flow from Monthly Data
Many needs exist in the energy industry where measurement is monthly yet daily values are required. The process of disaggregation of low frequency measurement to higher frequency values has been presented in this literature. Also, a novel method that accounts for prior-day weather impacts in the disaggregation process is presented, even though prior-day impacts are not directly recoverable from monthly data. Having initial daily weather and gas flow data, the weather and flow data are aggregated to generate simulated monthly weather and consumption data. Linear regression models can be powerful tools for parametrization of monthly/daily consumption models and will enable accurate disaggregation. Two-, three-, four-, and six-parameter linear regression models are built. RMSE and MAPE are used as means for assessing the performance of the proposed approach. Extensive comparisons between the monthly/daily gas consumption forecasts show higher accuracy of the results when the effect of prior-day weather inputs are considered
Is perpendicular magnetic anisotropy essential to all-optical ultrafast spin reversal in ferromagnets?
All-optical spin reversal presents a new opportunity for spin manipulations,
free of a magnetic field. Most of all-optical-spin-reversal ferromagnets are
found to have a perpendicular magnetic anisotropy (PMA), but it has been
unknown whether PMA is necessary for the spin reversal. Here we theoretically
investigate magnetic thin films with either PMA or in-plane magnetic anisotropy
(IMA). Our results show that the spin reversal in IMA systems is possible, but
only with a longer laser pulse and within a narrow laser parameter region. The
spin reversal does not show a strong helicity dependence where the left- and
right-circularly polarized light lead to the identical results. By contrast,
the spin reversal in PMA systems is robust, provided both the spin angular
momentum and laser field are strong enough while the magnetic anisotropy itself
is not too strong. This explains why experimentally the majority of all-optical
spin-reversal samples are found to have strong PMA and why spins in Fe
nanoparticles only cant out of plane. It is the laser-induced spin-orbit torque
that plays a key role in the spin reversal. Surprisingly, the same spin-orbit
torque results in laser-induced spin rectification in spin-mixed configuration,
a prediction that can be tested experimentally. Our results clearly point out
that PMA is essential to the spin reversal, though there is an opportunity for
in-plane spin reversal.Comment: 20 pages, 4 figures and one tabl
MAGNITUDE ESTIMATION: AN APPLICATION TO FARMERS' RISK-INCOME PREFERENCES
Magnitude estimation, a technique developed by psychology for obtaining ratio scaled values, was used to derive risk-income preferences of ninety-one central Indiana farmers. Both variability-income and bankruptcy-income measures were developed and related to farmers' socio-economic attributes. Wealth and education had limited effects compared with off-farm employment, percent debt and expected levels of income, percent debt and net worth growth. Magnitude estimation provided reliable estimates of preferences. Farmers gave greater importance to the bankruptcy-income measure of risk-income preferences, but only a small portion of the variation of either measure could be explained.Farm Management, Risk and Uncertainty,
Entropic Inflation
One of the major pillars of modern cosmology theory is a period of
accelerating expansion in the early universe. This accelerating expansion, or
inflation, must be sustained for at least 30 e--foldings. One mechanism used to
drive the acceleration is the addition of a new energy field, called the
Inflaton; often this is a scalar field. We propose an alternative mechanism
which, like our approach to explain the late-time accelerating universe, uses
the entropy and temperature intrinsic to information holographically stored on
a surface enclosing the observed space. The acceleration is due in both cases
to an emergent entropic force, naturally arising from the information storage
on the horizon.Comment: 12 pages; version to appear in IJMP
Robot-friendly connector
Robot friendly connectors, which, in one aspect, are truss joints with two parts, a receptacle and a joint, are presented. The joints have a head which is loosely inserted into the receptacle and is then tightened and aligned. In one aspect, the head is a rounded hammerhead which initially is enclosed in the receptacle with sloppy fit provided by the shape, size, and configuration of surfaces on the head and on the receptacle
Switching ferromagnetic spins by an ultrafast laser pulse: Emergence of giant optical spin-orbit torque
Faster magnetic recording technology is indispensable to massive data storage
and big data sciences. {All-optical spin switching offers a possible solution},
but at present it is limited to a handful of expensive and complex rare-earth
ferrimagnets. The spin switching in more abundant ferromagnets may
significantly expand the scope of all-optical spin switching. Here by studying
40,000 ferromagnetic spins, we show that it is the optical spin-orbit torque
that determines the course of spin switching in both ferromagnets and
ferrimagnets. Spin switching occurs only if the effective spin angular momentum
of each constituent in an alloy exceeds a critical value. Because of the strong
exchange coupling, the spin switches much faster in ferromagnets than
weakly-coupled ferrimagnets. This establishes a paradigm for all-optical spin
switching. The resultant magnetic field (65 T) is so big that it will
significantly reduce high current in spintronics, thus representing the
beginning of photospintronics.Comment: 12 page2, 6 figures. Accepted to Europhysics Letters (2016). Extended
version with the supplementary information. Contribution from Indiana State
University,Europhysics Letters (2016
- …