66,626 research outputs found
Effect of Land Application of Poultry Waste on Pesticide Loss
The poultry industry in Arkansas is a large, concentrated, growing industry that produces a high volume of fecal waste. Most of this waste is surface applied as pasture fertilizer. Pesticides are commonly used in the poultry industry for fly and litter beetle contro land are often a component of the surface-applied poultry waste. No information exists in the scientific literature regarding the transport of this pesticide component to nearby water supplies.Our research focused on cyromazine, a feed-through larvicide used to control flies in caged-layer hen houses. Tetrachlorvinphos and carbaryl are also used in poultry waste, but these pesticides have a relatively low solubility in water and rapid decomposition rate. Cyromazine, however, is highly soluble and stable in water. Since it may be readily washed from the pasture by heavy rainfall and may persist in surface and soil water, cyromazine appears to be potentially a much greater long-term threat to water quality than either carbaryl or tetrachlorvinphos. Therefore, the objective of this investigation was to examine the extent of cyromazine loss as a result of land application of caged layer manure. To quantify cyromazine loss from pasture plots treated with caged layer manure,research was conducted at the University of Arkansas Agricultural Experiment Station at Fayetteville. Plots of uniform slope were bordered to isolate surface runoff, fitted with runoff collectors, and established in fescue pasture. Suction lysimeters were placed at the 60 cm depth to sample soil water in the unsaturated zone. Caged layer manure was analyzed for cyromazine concentration and applied to the plots at three different rates. Rainfall was applied by simulator at two intensities. Surface runoff and lysimeter samples were measured and analyzed for cyromazine concentration. A solid phase extraction procedure was used to separate the cyromazine from the water samples and analysis was done by high performance liquid chromatography (HPLC). Results showed that a heavier manure application increased both the runoff and cyromazine concentration. Higher rainfall intensity also increased total cyromazine loss in the runoff, but provided enough runoff volume to decrease the cyromazine concentration. Soil water from the unsaturated zone was monitored for a year following the manure application, but neither cyromazine nor its metabolite, melamine, were detected
The longitudinal response function of the deuteron in chiral effective field theory
We use chiral effective field theory (EFT) to make predictions for the
longitudinal electromagnetic response function of the deuteron, f_L, which is
measured in d(e,e'N) reactions. In this case the impulse approximation gives
the full chiral EFT result up to corrections that are of O(P^4) relative to
leading. By varying the cutoff in the chiral EFT calculations between 0.6 and 1
GeV we conclude that the calculation is accurate to better than 10 % for values
of q^2 within 4 fm^{-2} of the quasi-free peak, up to final-state energies
E_{np}=60 MeV. In these regions chiral EFT is in reasonable agreement with
predictions for f_L obtained using the Bonn potential. We also find good
agreement with existing experimental data on f_L, albeit in a more restricted
kinematic domain.Comment: 33 pages, 10 figures. Accepted for publication in EPJA, with a few
further correction
Spin and localization of relativistic fermions and uncertainty relations
We discuss relations between several relativistic spin observables and derive
a Lorentz-invariant characteristic of a reduced spin density matrix.A
relativistic position operator that satisfies all the properties of its
nonrelativistic analog does not exist. Instead we propose two
causality-preserving positive operator-valued measures (POVMs) that are based
on projections onto one-particle and antiparticle spaces, and on the normalized
energy density. They predict identical expectation values for position. The
variances differ by less than a quarter of the squared de Broglie wavelength
and coincide in the nonrelativistic limit. Since the resulting statistical
moment operators are not canonical conjugates of momentum, the Heisenberg
uncertainty relations need not hold. Indeed, the energy density POVM leads to a
lower uncertainty. We reformulate the standard equations of the spin dynamics
by explicitly considering the charge-independent acceleration, allowing a
consistent treatment of backreaction and inclusion of a weak gravitational
field.Comment: Final version. The presentation is streamlined. Thanks to the
referees it can now be also used as a brief revie
Assessment of Effectiveness of Buffer Zones in Removing Impurities in Runoff from Areas Treated with Poultry Litter. Part II: Source Areas to Buffer Areas Ratio Effects
Vegetative filter strips (VFS) are known to reduce runoff losses of nutrients. solids. and other materials from land areas treated with fertilizers . Although VFS effectiveness is known to depend partially on the relative lengths of filter and pollutant source areas. there is little experimental evidence available to quantify this dependence. This is particularly the case when VFS are implemented down-slope of pasture areas treated with animal manures such as poultry litter. This study assessed the influences of pollutant source area (treated with poultry litter) and VFS lengths on VFS removal of total Kjeldahl nitrogen (TKN). ammonia nitrogen (NH3 -N ). nitrate nitrogen (N03-N). ortho-phosphorus (P04-P). total phosphorus (TP). total organic carbon (TOC). total suspended solids (TSS). and fecal coliform (FC) fromincoming runoff for a silt loam soil with fescue cover. Litter-treated lengths of 6.1. 12.2. and 18.3 m with corresponding VFS lengths of up to 18.3 m. 12.2 m. and 6.1 m. respectively, were examined. Runoff was produced from simulated rainfall applied at 50 mm/h for 1 h of runoff. Concentrations of the parameters analyzed were unaffected by litter treated length but demonstrated a first-order decrease with increasing VFS length except in the cases of TSS and FC. Mass transport of TKN. NH3-N. P04-P. and TP increased with increasing litter-treated length (due to increased runoff) and decreased (approximately first-order) with increasing VFS length. Effectiveness of the VFS in terms of TKN. NH3-N. P04 -P. and TP removal from runoff ranged from 6.5 to 96.3% depending on the particular parameter. litter-treated length. and VFS length. The data collected during this study can be helpful in developing and testing simulation models of VFS performance and can thus aid in design of VFS for pasture areas treated with poultry litter
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