394 research outputs found
Semantic categories underlying the meaning of ‘place’
This paper analyses the semantics of natural language expressions that are associated with the intuitive notion of ‘place’. We note that the nature of such terms is highly contested, and suggest that this arises from two main considerations: 1) there are a number of logically
distinct categories of place expression, which are not always clearly distinguished in discourse about ‘place’; 2) the many non-substantive place count nouns (such as ‘place’, ‘region’, ‘area’, etc.) employed in natural
language are highly ambiguous. With respect to consideration 1), we propose that place-related expressions
should be classified into the following distinct logical types: a) ‘place-like’ count nouns (further subdivided into abstract, spatial and substantive varieties), b) proper names of ‘place-like’ objects, c) locative property phrases, and d) definite descriptions of ‘place-like’ objects. We outline possible formal representations for each of these. To address consideration 2), we examine meanings, connotations and ambiguities of the English vocabulary of abstract and generic place count nouns, and identify underlying elements of meaning, which explain both
similarities and differences in the sense and usage of the various terms
Recovery of Fertilizer Nitrogen Under Field Conditions Using Nitrogen-15
An experiment was conducted under field conditions to study
the movement and recovery of N15-enriched nitrogen fertilizer
added to soil in the forms of NaNO2 and (NH4)2SO4. The plots
consisted of the soil mass inside cylinders 30 or 60 cm in diameter,
which were pressed into the soil to a depth of 45-60 cm. These
plots were either seeded to sudangrass (sorghum sudanense)
or left uncropped. The plant tops, roots, and the soil, by 15-cm layers, were analyzed for total N and excess N15 content.
Recovery of added N15 from the 32 plots ranged between 96.3
and 101.8%, and averaged 99.0%. There was no significant
difference in recovery of the fertilizer N due to the percent of
excess N15 in the fertilizer, size of plot, exposure to natural
rainfall, cropping, N source, or the time of application of the
fertilizer. Wide variation in recovery of excess N15 occurred with
core sampling and it was found necessary to remove, weigh, mix
and subsample the entire soil mass from within the rims. The
small amounts of unrecovered N were probably due to procedural
errors in the field and laboratory, and leaching and root growth
beyond the sampling zone. There was no indication of any N
loss in the gaseous form.
The fate of applied fertilizer N was followed under field
conditions using N15-enriched nitrogen fertilizer applied to the
soil in situ enclosed by large steel cylinders. Total recovery
of the fertilizer N from these experiments after 8 weeks ranged
from 88 to 96%, but dropped as low as 77% after 10 months.
Recovery of the fertilizer N was greater from an ammonium
source than from nitrate. Better recovery of fertilizer was
obtained when the plots were cropped to sudangrass rather than
left fallow. Doubling the rate of application of the fertilizer N
from 336 to 672 kg/ha did not affect percent of total recovery.
The 4 to 12% of fertilizer N unrecovered after 8 weeks appears
to be due to a loss in the gaseous form, since special precautions
were taken to restrict leaching and to eliminate errors in sampling
and analysis
Fate and occurrence of alkylphenolic compounds in sewage sludges determined by liquid chromatography tandem mass spectrometry
This is the author's accepted manuscript. The final published article is available from the link below. Copyright @ 2009 Taylor & Francis.An analytical method has been developed and applied to determine the concentrations of the nonionic alkylphenol polyethoxylate surfactants and their metabolites, alkylphenoxy carboxylates and alkyphenols, in sewage sludges. The compounds were extracted with methanol/acetone (1:1 v/v) from sludge, and concentrated extracts were cleaned by silica solid‐phase extraction prior to determination by liquid chromatography tandem mass spectrometry. The recoveries, determined by spiking sewage sludge at two concentrations, ranged from 51% to 89% with method detection limits from 6 µg kg−1 to 60 µg kg−1. The methodology was subsequently applied to sludge samples obtained from a carbonaceous activated sludge plant, a nitrifying/denitrifying activated sludge plant and a nitrifying/denitrifying activated sludge plant with phosphorus removal. Concentrations of nonylphenolic compounds were two to three times higher than their octyl analogues. Long‐chain nonylphenol polyethoxylates (NP3–12EO) ranged from 16 µg kg−1 to 11754 µg kg−1. The estrogenic metabolite nonylphenol was present at concentrations ranging from 33 µg kg−1 to 6696 µg kg−1.Public Utilities Board of Singapore, Thames Water and Yorkshire Water
Lagrangian evolution of global strings
We establish a method to trace the Lagrangian evolution of extended objects
consisting of a multicomponent scalar field in terms of a numerical calculation
of field equations in three dimensional Eulerian meshes. We apply our method to
the cosmological evolution of global strings and evaluate the energy density,
peculiar velocity, Lorentz factor, formation rate of loops, and emission rate
of Nambu-Goldstone (NG) bosons. We confirm the scaling behavior with a number
of long strings per horizon volume smaller than the case of local strings by a
factor of 10. The strategy and the method established here are
applicable to a variety of fields in physics.Comment: 5 pages, 2 figure
Lepton Flavour Violation in a Class of Lopsided SO(10) Models
A class of predictive SO(10) grand unified theories with highly asymmetric
mass matrices, known as lopsided textures, has been developed to accommodate
the observed mixing in the neutrino sector. The model class effectively
determines the rate for charged lepton flavour violation, and in particular the
branching ratio for , assuming that the supersymmetric GUT
breaks directly to the constrained minimal supersymmetric standard model
(CMSSM). We find that in light of the combined constraints on the CMSSM
parameters from direct searches and from the WMAP satellite observations, the
resulting predicted rate for in this model class can be
within the current experimental bounds for low , but that the next
generation of experiments would effectively rule out this
model class if LFV is not detected.Comment: 23 page
String Imprints from a Pre-inflationary Era
We derive the equations governing the dynamics of cosmic strings in a flat
anisotropic universe of Bianchi type I and study the evolution of simple cosmic
string loop solutions. We show that the anisotropy of the background can have a
characteristic effect in the loop motion. We discuss some cosmological
consequences of these findings and, by extrapolating our results to cosmic
string networks, we comment on their ability to survive an inflationary epoch,
and hence be a possible fossil remnant (still visible today) of an anisotropic
phase in the very early universe.Comment: 5 pages, 3 figure
Butyltin compounds in a sediment core from the old Tilbury basin, London, UK
Sections from a sediment core taken from the River Thames were analysed for butyltin species using gas chromatography with species-specific isotope dilution mass spectrometry. Results demonstrated that in most samples tributyltin concentrations of 20–60 ng/g accounted for <10% of the total butyltin species present, which is in agreement with data from other sediment samples which were historically contaminated with tributyltin. Vertical distribution of the organotin residues with depth throughout the core, with data on organochlorine compounds and heavy metals allowed for the construction of a consistent hypothesis on historical deposition of contaminated sediments. From this it was possible to infer that the concentrations of tributyltin in sediments deposited during the early 1960s were in the order of 400–600 lg/g by using degradation rate constants derived by other workers. Such values fall well within the range quoted for harbour sediments in the literature
Scaling in Numerical Simulations of Domain Walls
We study the evolution of domain wall networks appearing after phase
transitions in the early Universe. They exhibit interesting dynamical scaling
behaviour which is not yet well understood, and are also simple models for the
more phenomenologically acceptable string networks. We have run numerical
simulations in two- and three-dimensional lattices of sizes up to 4096^3. The
theoretically predicted scaling solution for the wall area density A ~ 1/t is
supported by the simulation results, while no evidence of a logarithmic
correction reported in previous studies could be found. The energy loss
mechanism appears to be direct radiation, rather than the formation and
collapse of closed loops or spheres. We discuss the implications for the
evolution of string networks.Comment: 7pp RevTeX, 9 eps files (including six 220kB ones
Solar Neutrino Constraints on the BBN Production of Li
Using the recent WMAP determination of the baryon-to-photon ratio, 10^{10}
\eta = 6.14 to within a few percent, big bang nucleosynthesis (BBN)
calculations can make relatively accurate predictions of the abundances of the
light element isotopes which can be tested against observational abundance
determinations. At this value of \eta, the Li7 abundance is predicted to be
significantly higher than that observed in low metallicity halo dwarf stars.
Among the possible resolutions to this discrepancy are 1) Li7 depletion in the
atmosphere of stars; 2) systematic errors originating from the choice of
stellar parameters - most notably the surface temperature; and 3) systematic
errors in the nuclear cross sections used in the nucleosynthesis calculations.
Here, we explore the last possibility, and focus on possible systematic errors
in the He3(\alpha,\gamma)Be7 reaction, which is the only important Li7
production channel in BBN. The absolute value of the cross section for this key
reaction is known relatively poorly both experimentally and theoretically. The
agreement between the standard solar model and solar neutrino data thus
provides additional constraints on variations in the cross section (S_{34}).
Using the standard solar model of Bahcall, and recent solar neutrino data, we
can exclude systematic S_{34} variations of the magnitude needed to resolve the
BBN Li7 problem at > 95% CL. Additional laboratory data on
He3(\alpha,\gamma)Be7 will sharpen our understanding of both BBN and solar
neutrinos, particularly if care is taken in determining the absolute cross
section and its uncertainties. Nevertheless, it already seems that this
``nuclear fix'' to the Li7 BBN problem is unlikely; other possible solutions
are briefly discussed.Comment: 21 pages, 3 ps figure
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