6,953 research outputs found
The Behavior of Soluble Salt in Sharkey Clay
Soluble salt problems do exist and are significant in Arkansas. Studies have been conducted on Crowley silt loam (Typic Albaqualfs) which have established the behavior of soluble salt in that soil. The major objective of this study was to quantify the behavior of soluble salt in a second important Mississippi River Delta soil - the Sharkey (Vertic Haplaquepts). To this end, estimation of the downward redistribution of salt and the estimation of various components of the water balance for this soil served as specific objectives. Field studies were designed to monitor the movement of salt in the Sharkey soil and to characterize selected components of the water balance. In total, three tentative conclusions may be drawn from the data. First, the infiltration for the Sharkey soil was approximately three times that of the Crowley silt loam. The average value was 29 cm for the rice season. Second, levee seepage, while significant for small plots, was shown to be small for production-sized fields. Levee seepage remained relatively constant throughout the season and averaged 0.025 nvfym/d. And third, downward redistribution of salt was large and appeared to follow a pattern where a peak occurred at the surface and, possibly, at the lower soil depths
The Behavior of Soluble Salt in Sharkey Clay- II
Soluble salts have been shown to accumulate in Arkansas soils in sufficient quantities to impair crop plant growth. The major objective of this study was to describe the behavior of soluble chloride salt over long time periods in Sharkey clay - a major Mississippi Delta soil. Prior to flooding rice, leaching of chloride in response to rainfall was observed. The inclusion of a sandy subsoil layer reduced this effect presumably by limiting downward movement of water under unsaturated conditions. No lateral movement of the chloride salt was found during the period prior to flooding. Removal of soluble chloride salts from the top 100 cm of Sharkey soil was complete in a 1-2 year period depending on weather conditions. In a year where the rice cropping season was followed by a wet winter, losses were smaller than in a year where the rice cropping season was followed by a drier winter. These results suggested that removal of soluble salts via leaching in this soil was more efficient under less saturated soil conditions
The Clover Root Weevil Invasion: Impact and Response of the New Zealand Pastoral Industry 1996-2012
Clover root weevil, Sitona lepidus Gyllenhall (Curculionidae: Coleoptera), was first reported in New Zealand in 1996. With few natural enemies or competitors, it rapidly became a major pest of white clover. Its strong flight capability, tendency to be transported in agricultural machinery and vehicles, and wide climatic tolerance enabled it to spread the length of the country (1,600 km) by 2010. The most damaging stage is the larva, which attacks the roots, root nodules and stolons of clovers, reducing herbage production (particularly in spring), pasture clover content, and nitrogen fixation. From the time of the initial invasion, the pastoral industry supported research into management as insecticides were not a viable option. Nitrogen fertiliser applications after grazing were recommended to maintain production. Field evaluations showed that white clovers with good general agronomic adaptation survived better under weevil pressure than less-adapted clovers. In 2006, a parasitic wasp, Microctonus aethiopoides Loan (Braconidae: Hymenoptera), was introduced from Ireland for biological control of S. lepidus. It has also established and dispersed very rapidly, and often suppresses weevil populations within 2 â 3 years of its establishment in a new locality. Involvement of industry field consultants was an essential aspect of the biological control release programme in the North Island where the weevil was already widespread before M. aethiopoides was introduced
PAndAS in the mist: The stellar and gaseous mass within the halos of M31 and M33
Large scale surveys of the prominent members of the Local Group have provided
compelling evidence for the hierarchical formation of massive galaxies,
revealing a wealth of substructure that is thought to be the debris from
ancient and on-going accretion events. In this paper, we compare two extant
surveys of the M31-M33 subgroup of galaxies; the Pan-Andromeda Archaeological
Survey (PAndAS) of the stellar structure, and a combination of observations of
the HI gaseous content, detected at 21cm. Our key finding is a marked lack of
spatial correlation between these two components on all scales, with only a few
potential overlaps between stars and gas.The paucity of spatial correlation
significantly restricts the analysis of kinematic correlations, although there
does appear to the HI kinematically associated with the Giant Stellar Stream
where it passes the disk of M31. These results demonstrate that that different
processes must significantly influence the dynamical evolution of the stellar
and HI components of substructures, such as ram pressure driving gas away from
a purely gravitational path. Detailed modelling of the offset between the
stellar and gaseous substructure will provide a determination of the properties
of the gaseous halo of M31 and M33.Comment: 11 pages, 6 figures. Accepted for publication in the Astrophysical
Journal. Figure quality reduced. High quality version available at
http://www.physics.usyd.edu.au/~gfl/Arxiv_Papers/PAndAS_Mist
Using the affective priming paradigm to explore the attitudes underlying walking behaviour
Objectives. Walking is poorly represented in memory, making it difficult to measure
using self-report and even harder to predict. To circumvent this, we used the affective
priming paradigm (Fazio, Sanbonmatsu, Powell, & Kardes, 1986) to assess implicit
attitudes towards walking.
Methods. Royal Air Force trainee aircraftsmen (N Œ 188) wore pedometers for 1
week prior to completing the affective priming paradigm, questionnaire and interview.
The affective priming paradigm involved a computer-based response latency task
containing physical activity words as primes followed by adjectives as targets to be
evaluated. Targets were drawn from two bipolar dichotomies, goodâbad (the original
Fazio et al. items) and happyâsad (mood).
Results. Priming for mood items was related to levels of physical activity with high
frequency participants priming for the positive (happy) pole and low frequency
participants priming for the negative (sad). Both groups primed for the negative element
of the Fazio (goodâbad) dichotomy. Regarding walking and running, there was no
differentiation on the basis of participation level. Instead, facilitated responses to happy
targets contrasted with inhibited responses to sad targets for both types of locomotion.
There was weak evidence that intentions to run were associated with priming of
positive target items, irrespective of category.
Conclusions. The relationship between implicit attitudes and behaviour is complex.
Whereas implicit attitudes were related to overall exercise participation, they were not
related to the specific activity of walking, despite the behaviour being mainly under
automatic control.</p
Doing Biopolitics Differently? Radical Potential in the Post-2015 MDG and SDG Debates
Post print On institutional repository or subject-based repository after a 18 months embargo, withdraw
The masses of Local Group dwarf spheroidal galaxies: The death of the universal mass profile
We investigate the claim that all dwarf spheroidal galaxies (dSphs) reside
within halos that share a common, universal mass profile as has been derived
for dSphs of the Galaxy. By folding in kinematic information for 25 Andromeda
dSphs, more than doubling the previous sample size, we find that a singular
mass profile can not be found to fit all the observations well. Further, the
best-fit dark matter density profile measured for solely the Milky Way dSphs is
marginally discrepant (at just beyond the 1 sigma level) with that of the
Andromeda dSphs, where a profile with lower maximum circular velocity, and
hence mass, is preferred. The agreement is significantly better when three
extreme Andromeda outliers, And XIX, XXI and XXV, all of which have large
half-light radii (>600pc) and low velocity dispersions (sigma_v < 5km/s) are
omitted from the sample. We argue that the unusual properties of these outliers
are likely caused by tidal interactions with the host galaxy.Comment: ApJ in press, 16 pages, 7 figures. Updated to address referee
comment
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