538 research outputs found
Dicamba Resistance: Enlarging and Preserving Biotechnology-Based Weed Management Strategies
The advent of biotechnology-derived, herbicide-resistant crops has revolutionized farming practices in many countries. Facile, highly effective, environmentally sound, and profitable weed control methods have been rapidly adopted by crop producers who value the benefits associated with biotechnology-derived weed management traits. But a rapid rise in the populations of several troublesome weeds that are tolerant or resistant to herbicides currently used in conjunction with herbicide-resistant crops may signify that the useful lifetime of these economically important weed management traits will be cut short. We describe the development of soybean and other broadleaf plant species resistant to dicamba, a widely used, inexpensive, and environmentally safe herbicide. The dicamba resistance technology will augment current herbicide resistance technologies and extend their effective lifetime. Attributes of both nuclear- and chloroplast- encoded dicamba resistance genes that affect the potency and expected durability of the herbicide resistance trait are examined
Dicamba Resistance: Enlarging and Preserving Biotechnology-Based Weed Management Strategies
The advent of biotechnology-derived, herbicide-resistant crops has revolutionized farming practices in many countries. Facile, highly effective, environmentally sound, and profitable weed control methods have been rapidly adopted by crop producers who value the benefits associated with biotechnology-derived weed management traits. But a rapid rise in the populations of several troublesome weeds that are tolerant or resistant to herbicides currently used in conjunction with herbicide-resistant crops may signify that the useful lifetime of these economically important weed management traits will be cut short. We describe the development of soybean and other broadleaf plant species resistant to dicamba, a widely used, inexpensive, and environmentally safe herbicide. The dicamba resistance technology will augment current herbicide resistance technologies and extend their effective lifetime. Attributes of both nuclear- and chloroplast- encoded dicamba resistance genes that affect the potency and expected durability of the herbicide resistance trait are examined
The X-ray Afterglows of GRB 020813 and GRB 021004 with Chandra HETGS: Possible Evidence for a Supernova Prior to GRB 020813
We report on the detection of an emission line near 1.3 keV, which we
associate with blue-shifted hydrogen-like sulfur (S XVI), in a 76.8 ksec
Chandra HETGS spectrum of the afterglow of GRB 020813. The line is detected at
3.3 sigma significance. We also find marginal evidence for a line possibly due
to hydrogen-like silicon (Si XIV) with the same blue-shift. A line from Fe is
not detected, though a very low significance Ni feature may be present. A
thermal model fits the data adequately, but a reflection model may provide a
better fit. There is marginal evidence that the equivalent width of the S XVI
line decrease as the burst fades. We infer from these results that a supernova
likely occurred >~ 2 months prior to the GRB. We find no discrete or variable
spectral features in the Chandra HETGS spectrum of the GRB 021004 afterglow.Comment: 26 pages, 11 figures, submitted to Ap
Confluence and Convergence in Probabilistically Terminating Reduction Systems
Convergence of an abstract reduction system (ARS) is the property that any
derivation from an initial state will end in the same final state, a.k.a.
normal form. We generalize this for probabilistic ARS as almost-sure
convergence, meaning that the normal form is reached with probability one, even
if diverging derivations may exist. We show and exemplify properties that can
be used for proving almost-sure convergence of probabilistic ARS, generalizing
known results from ARS.Comment: Pre-proceedings paper presented at the 27th International Symposium
on Logic-Based Program Synthesis and Transformation (LOPSTR 2017), Namur,
Belgium, 10-12 October 2017 (arXiv:1708.07854
Amenability of groups and -sets
This text surveys classical and recent results in the field of amenability of
groups, from a combinatorial standpoint. It has served as the support of
courses at the University of G\"ottingen and the \'Ecole Normale Sup\'erieure.
The goals of the text are (1) to be as self-contained as possible, so as to
serve as a good introduction for newcomers to the field; (2) to stress the use
of combinatorial tools, in collaboration with functional analysis, probability
etc., with discrete groups in focus; (3) to consider from the beginning the
more general notion of amenable actions; (4) to describe recent classes of
examples, and in particular groups acting on Cantor sets and topological full
groups
The Effect of Male Incarceration on Rape Myth Acceptance: Application of Propensity Score Matching Technique
The aim is to assess the effect of imprisonment on rape myth acceptance. The research used a sample of male prisoners incarcerated for non-sexual crimes (n = 98) and a sample of males drawn from the general population (n = 160). Simple linear regression did not indicate a significant effect of incarceration on rape myth acceptance. After controlling for background covariates using propensity score matching, analysis revealed a positive significant effect of incarceration on rape myth acceptance. Although further research is required, results indicate that being subject to incarceration has a significant positive effect on stereotypical thinking about rape
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REMOVING SLUDGE HEELS FROM SAVANNAH RIVER SITE WASTE TANKS BY OXALIC ACID DISSOLUTION
The Savannah River Site (SRS) will remove sludge as part of waste tank closure operations. Typically the bulk sludge is removed by mixing it with supernate to produce a slurry, and transporting the slurry to a downstream tank for processing. Experience shows that a residual heel may remain in the tank that cannot be removed by this conventional technique. In the past, SRS used oxalic acid solutions to disperse or dissolve the sludge heel to complete the waste removal. To better understand the actual conditions of oxalic acid cleaning of waste from carbon steel tanks, the authors developed and conducted an experimental program to determine its effectiveness in dissolving sludge, the hydrogen generation rate, the generation rate of other gases, the carbon steel corrosion rate, the impact of mixing on chemical cleaning, the impact of temperature, and the types of precipitates formed during the neutralization process. The test samples included actual SRS sludge and simulated SRS sludge. The authors performed the simulated waste tests at 25, 50, and 75 C by adding 8 wt % oxalic acid to the sludge over seven days. They conducted the actual waste tests at 50 and 75 C by adding 8 wt % oxalic acid to the sludge as a single batch. Following the testing, SRS conducted chemical cleaning with oxalic acid in two waste tanks. In Tank 5F, the oxalic acid (8 wt %) addition occurred over seven days, followed by inhibited water to ensure the tank contained enough liquid to operate the mixer pumps. The tank temperature during oxalic acid addition and dissolution was approximately 45 C. The authors analyzed samples from the chemical cleaning process and compared it with test data. The conclusions from the work are: (1) Oxalic acid addition proved effective in dissolving sludge heels in the simulant demonstration, the actual waste demonstration, and in SRS Tank 5F. (2) The oxalic acid dissolved {approx} 100% of the uranium, {approx} 100% of the iron, and {approx} 40% of the manganese during a single contact in the simulant demonstration. (The iron dissolution may be high due to corrosion of carbon steel coupons.) (3) The oxalic acid dissolved {approx} 80% of the uranium, {approx} 70% of the iron, {approx} 50% of the manganese, and {approx} 90% of the aluminum in the actual waste demonstration for a single contact. (4) The oxalic acid dissolved {approx} 100% of the uranium, {approx} 15% of the iron, {approx} 40% of the manganese, and {approx} 80% of the aluminum in Tank 5F during the first contact cycle. Except for the iron, these results agree well with the demonstrations. The data suggest that a much larger fraction of the iron in the sludge dissolved, but it re-precipitated with the oxalate added to Tank 5F. (5) The demonstrations produced large volumes (i.e., 2-14 gallons of gas/gallon of oxalic acid) of gas (primarily carbon dioxide) by the reaction of oxalic acid with sludge and carbon steel. (6) The reaction of oxalic acid with carbon steel produced hydrogen in the simulant and actual waste demonstrations. The volume produced varied from 0.00002-0.00100 ft{sup 3} hydrogen/ft{sup 2} carbon steel. The hydrogen production proved higher in unmixed tanks than in mixed tanks
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