568 research outputs found
A 3D geological background for Knowsley Industrial Park and surrounding areas, NW England
This report describes the results of a study carried out by the British Geological Survey (BGS)
on behalf of the Environment Agency NW to investigate the underlying geology beneath
Knowsley Industrial Park, Merseyside, NW England. The overarching aim of the project was to
establish a 3D geoscience framework beneath the Knowsley Industrial Park to enable the
Environment Agency (the Agency) to assess the vulnerability of the underlying Sherwood
Sandstone aquifer. The vulnerability of the aquifer to pollution from current and historic
contamination of land, potentially leaking foul sewers and contaminated surface water drains
could then be assessed by reference to the underlying geology.
In addition to the 3D geological model, United Utilities pipeline data for foul and surface water
drainage was provided by the Agency. This pipeline information was analysed and integrated
with the geological data to provide an assessment of the potential linkage between the pipes and
the underling bedrock or superficial geology in which they are sited.
Over 300 additional paper borehole records were provided by the Agency from previous
environmental site investigations carried out in the industrial park and incorporated into the BGS
databases. In total, 1279 coded boreholes were used in the study. Of these, 733 were used to
construct 58 geological cross-sections.
The 3D geological model revealed a sequence of superficial deposits across the site comprising
glacial, post-glacial and artificial deposits overlying the Sherwood Sandstone Group, that in
places are deeply weathered to form loose sand. In the south-east and north-west of the site,
rocks belonging to the Sherwood Sandstone Group crop out at surface. The vulnerability of the
Sherwood Sandstone aquifer beneath the site, to pollution from contaminated water, depends in
part on the distribution and thickness of weakly permeable superficial deposits such as clay or
silt. The geological model has revealed that till is the only clay dominated unit present beneath
the site and for this reason, invert levels of foul and surface water pipes were compared to this
geological deposit as it may influence the potential vulnerability of the underlying aquifer. Invert
levels represent the elevation of the base of the pipe.
4722 pipeline segments were analysed and classified according to their minimum invert level
(representing the maximum depth below ground level) recorded for each segment. This
information was used to identify pipeline segments that occurred above, below or within till.
Pipeline segments interpreted to lie within or above the till were subdivided according to
whether they were underlain by greater or less than 2.5 m of till. 2.5 m represents the average
thickness of till calculated from the 3D geological model. Pipeline segments whose invert level
occurs beneath the till will lie directly within the Sherwood Sandstone aquifer or sand and gravel
dominated superficial deposits and therefore the relative hazard potential may be higher than
those where clay dominated superficial deposits occur between them and the underlying aquifer.
In general, the results indicate that the northern part of Knowsley Industrial Park and the northwestern
part of the wider project area are underlain by greater than 2.5 m of till and that pipelines
lie above the top surface of the till or within it. In contrast, the southern part of Knowsley
Industrial Park and the south-western part of the wider project area are underlain generally by
less than 2.5 m of till and pipeline segments occur below the till or directly within the Sherwood
Sandstone aquifer.
This information can be used as a preliminary screening or prioritisation tool. It can identify
potential areas where the Sherwood Sandstone aquifer is most vulnerable to pollution from
contaminated groundwater from poor condition, potentially leaking sewers and drains in the
subsurface
Wave Propagation in Gravitational Systems: Late Time Behavior
It is well-known that the dominant late time behavior of waves propagating on
a Schwarzschild spacetime is a power-law tail; tails for other spacetimes have
also been studied. This paper presents a systematic treatment of the tail
phenomenon for a broad class of models via a Green's function formalism and
establishes the following. (i) The tail is governed by a cut of the frequency
Green's function along the ~Im~ axis,
generalizing the Schwarzschild result. (ii) The dependence of the cut
is determined by the asymptotic but not the local structure of space. In
particular it is independent of the presence of a horizon, and has the same
form for the case of a star as well. (iii) Depending on the spatial
asymptotics, the late time decay is not necessarily a power law in time. The
Schwarzschild case with a power-law tail is exceptional among the class of the
potentials having a logarithmic spatial dependence. (iv) Both the amplitude and
the time dependence of the tail for a broad class of models are obtained
analytically. (v) The analytical results are in perfect agreement with
numerical calculations
New empirical fits to the proton electromagnetic form factors
Recent measurements of the ratio of the elastic electromagnetic form factors
of the proton, G_Ep/G_Mp, using the polarization transfer technique at
Jefferson Lab show that this ratio decreases dramatically with increasing Q^2,
in contradiction to previous measurements using the Rosenbluth separation
technique. Using this new high quality data as a constraint, we have reanalyzed
most of the world e-p elastic cross section data. In this paper, we present a
new empirical fit to the reanalyzed data for the proton elastic magnetic form
factor in the region 0 < Q^2 < 30 GeV^2. As well, we present an empirical fit
to the proton electromagnetic form factor ratio, G_Ep/G_Mp, which is valid in
the region 0.1 < Q^2 < 6 GeV^2
The global atmospheric electrical circuit and climate
Evidence is emerging for physical links among clouds, global temperatures, the global atmospheric electrical circuit and cosmic ray ionisation. The global circuit extends throughout the atmosphere from the planetary surface to the lower layers of the ionosphere. Cosmic rays are the principal source of atmospheric ions away from the continental boundary layer: the ions formed permit a vertical conduction current to flow in the fair weather part of the global circuit. Through the (inverse) solar modulation of cosmic rays, the resulting columnar ionisation changes may allow the global circuit to convey a solar influence to meteorological phenomena of the lower atmosphere. Electrical effects on non-thunderstorm clouds have been proposed to occur via the ion-assisted formation of ultra-fine aerosol, which can grow to sizes able to act as cloud condensation nuclei, or through the increased ice nucleation capability of charged aerosols. Even small atmospheric electrical modulations on the aerosol size distribution can affect cloud properties and modify the radiative balance of the atmosphere, through changes communicated globally by the atmospheric electrical circuit. Despite a long history of work in related areas of geophysics, the direct and inverse relationships between the global circuit and global climate remain largely quantitatively unexplored. From reviewing atmospheric electrical measurements made over two centuries and possible paleoclimate proxies, global atmospheric electrical circuit variability should be expected on many timescale
Radiative falloff of a scalar field in a weakly curved spacetime without symmetries
We consider a massless scalar field propagating in a weakly curved spacetime
whose metric is a solution to the linearized Einstein field equations. The
spacetime is assumed to be stationary and asymptotically flat, but no other
symmetries are imposed -- the spacetime can rotate and deviate strongly from
spherical symmetry. We prove that the late-time behavior of the scalar field is
identical to what it would be in a spherically-symmetric spacetime: it decays
in time according to an inverse power-law, with a power determined by the
angular profile of the initial wave packet (Price falloff theorem). The field's
late-time dynamics is insensitive to the nonspherical aspects of the metric,
and it is governed entirely by the spacetime's total gravitational mass; other
multipole moments, and in particular the spacetime's total angular momentum, do
not enter in the description of the field's late-time behavior. This extended
formulation of Price's falloff theorem appears to be at odds with previous
studies of radiative decay in the spacetime of a Kerr black hole. We show,
however, that the contradiction is only apparent, and that it is largely an
artifact of the Boyer-Lindquist coordinates adopted in these studies.Comment: 17 pages, RevTeX
The arrow of time: from universe time-asymmetry to local irreversible processes
In several previous papers we have argued for a global and non-entropic
approach to the problem of the arrow of time, according to which the ''arrow''
is only a metaphorical way of expressing the geometrical time-asymmetry of the
universe. We have also shown that, under definite conditions, this global
time-asymmetry can be transferred to local contexts as an energy flow that
points to the same temporal direction all over the spacetime. The aim of this
paper is to complete the global and non-entropic program by showing that our
approach is able to account for irreversible local phenomena, which have been
traditionally considered as the physical origin of the arrow of time.Comment: 48 pages, 8 figures, revtex4. Accepted for publication in Foundations
of Physic
Nucleon Charge and Magnetization Densities from Sachs Form Factors
Relativistic prescriptions relating Sachs form factors to nucleon charge and
magnetization densities are used to fit recent data for both the proton and the
neutron. The analysis uses expansions in complete radial bases to minimize
model dependence and to estimate the uncertainties in radial densities due to
limitation of the range of momentum transfer. We find that the charge
distribution for the proton is significantly broad than its magnetization
density and that the magnetization density is slightly broader for the neutron
than the proton. The neutron charge form factor is consistent with the Galster
parametrization over the available range of Q^2, but relativistic inversion
produces a softer radial density. Discrete ambiguities in the inversion method
are analyzed in detail. The method of Mitra and Kumari ensures compatibility
with pQCD and is most useful for extrapolating form factors to large Q^2.Comment: To appear in Phys. Rev. C. Two new figures and accompanying text have
been added and several discussions have been clarified with no significant
changes to the conclusions. Now contains 47 pages including 21 figures and 2
table
Severe respiratory illness caused by a novel coronavirus, in a patient transferred to the United Kingdom from the Middle East, September 2012
Coronaviruses have the potential to cause severe transmissible human disease, as demonstrated by the severe acute respiratory syndrome (SARS) outbreak of 2003. We describe here the clinical and virological features of a novel coronavirus infection causing severe respiratory illness in a patient transferred to London, United Kingdom, from the Gulf region of the Middle East
Muon Track Reconstruction and Data Selection Techniques in AMANDA
The Antarctic Muon And Neutrino Detector Array (AMANDA) is a high-energy
neutrino telescope operating at the geographic South Pole. It is a lattice of
photo-multiplier tubes buried deep in the polar ice between 1500m and 2000m.
The primary goal of this detector is to discover astrophysical sources of high
energy neutrinos. A high-energy muon neutrino coming through the earth from the
Northern Hemisphere can be identified by the secondary muon moving upward
through the detector. The muon tracks are reconstructed with a maximum
likelihood method. It models the arrival times and amplitudes of Cherenkov
photons registered by the photo-multipliers. This paper describes the different
methods of reconstruction, which have been successfully implemented within
AMANDA. Strategies for optimizing the reconstruction performance and rejecting
background are presented. For a typical analysis procedure the direction of
tracks are reconstructed with about 2 degree accuracy.Comment: 40 pages, 16 Postscript figures, uses elsart.st
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