2,356 research outputs found
G-BASE data conditioning procedures for stream sediment and soil chemical analyses
Data conditioning is the process of making data fit for the purpose for which it is to be used and forms a significant component of the G-BASE project. This report is part of a series of manuals to record G-BASE project methodology. For data conditioning this has been difficult as applications used for processing data and the way in which data are reported continue to evolve rapidly and sections of this report have had to be continually updated to reflect this fact. However, the principals of data conditioning have changed little since the BGS regional geochemical mapping started in the late 1960s.
The process of data conditioning is based on one or more quality control procedures applied to the geochemical results as received from the laboratories, the degree of conditioning depending on how the data is to be used. The task is based on "blind" control samples being inserted prior to analysis, a system of quality control described in the G-BASE procedures manual. The first of the data conditioning processes is data verification and error checking, essentially assessing whether the laboratory has done what it was asked to do and results are being reported with reasonable accuracy. Shewhart or control charts form an important part of this process.
Once the data has been error checked, verified and accepted from the laboratory, further analysis of the data is carried out. These processes include: a series of x-y plots (of duplicate and replicate samples), more detailed control chart plots, and ANOVA analysis of the duplicate/replicate pairs to allocate variance in the results to sampling, analytical or between site variability. Analysis of both primary and secondary reference material can quantify analytical accuracy and precision. An important part of the data conditioning is the quality assurance and this includes procedures used for dealing with results that have data quality issues and documenting all parts of the data conditioning procedure.
The final part of the data conditioning procedure is necessary in order to use the data in context of other previously analysed data sets. This is the process of normalisation and levelling of the data. In G-BASE this is a very necessary step in order to create seamless geochemical maps and images across campaign boundaries and varying analytical methodologies that have spanned several decades
G-BASE field procedures manual : version 1.1
The G-BASE project is a long-term systematic geochemical survey that has required a high degree
of consistency in its sampling methodologies. This report gives in detail all the project procedures
associated with the collection of geochemical samples from the planning phase in the office through
to sample reception and reporting of the completed field campaign. The procedures described here
should be diligently followed in order to maintain the high levels of quality control the project
aspires to. Any changes to procedures are indicated in the latest version of this manual and
documented in an updates list in Annex I.
In addition to describing all the fieldwork procedures, the recruitment and training of "voluntary"
student workers is described along with discussions relating to health and safety issues likely to be
encountered during sampling.
When describing the methods used by G-BASE in reports or publications, reference should be
made to this manual
GSUE: urban geochemical mapping in Great Britain
The British Geological Survey is responsible for the national strategic geochemical survey of Great Britain. As part of this programme, the Geochemical Surveys of Urban Environments (GSUE) project was initiated in 1992 and to date, 21 cities have been mapped. Urban sampling is based upon the collection of top (0.05 to 0.20 m) and deeper (0.35 to 0.50 m) soil samples on a 500 m grid across the built environment (1 sample per 0.25 km2). Samples are analysed for c. 46 total element concentrations by X-ray Fluorescence Spectrometry (XRFS), pH and loss on ignition (LOI) as an indicator of organic matter content. The data provide an overview of the urban geochemical signature and because they are collected as part of a national baseline programme, can be readily compared with soils in the rural hinterland to assess the extent of urban contamination. The data are of direct relevance to current UK land use planning, urban regeneration and contaminated land legislative regimes. An overview of the project and applications of the data to human health risk assessment, water quality protection and contaminant source identification are presented
Tachyon Condensation, Open-Closed Duality, Resolvents, and Minimal Bosonic and Type 0 Strings
Type 0A string theory in the (2,4k) superconformal minimal model backgrounds
and the bosonic string in the (2,2k-1) conformal minimal models, while
perturbatively identical in some regimes, may be distinguished
non-perturbatively using double scaled matrix models. The resolvent of an
associated Schrodinger operator plays three very important interconnected
roles, which we explore perturbatively and non-perturbatively. On one hand, it
acts as a source for placing D-branes and fluxes into the background, while on
the other, it acts as a probe of the background, its first integral yielding
the effective force on a scaled eigenvalue. We study this probe at disc, torus
and annulus order in perturbation theory, in order to characterize the effects
of D-branes and fluxes on the matrix eigenvalues. On a third hand, the
integrated resolvent forms a representation of a twisted boson in an associated
conformal field theory. The entire content of the closed string theory can be
expressed in terms of Virasoro constraints on the partition function, which is
realized as wavefunction in a coherent state of the boson. Remarkably, the
D-brane or flux background is simply prepared by acting with a vertex operator
of the twisted boson. This generates a number of sharp examples of open-closed
duality, both old and new. We discuss whether the twisted boson conformal field
theory can usefully be thought of as another holographic dual of the
non-critical string theory.Comment: 37 pages, some figures, LaTe
Minimum connected transversals in graphs: New hardness results and tractable cases using the price of connectivity
We perform a systematic study in the computational complexity of the connected variant of three related transversal problems: Vertex Cover, Feedback Vertex Set, and Odd Cycle Transversal. Just like their original counterparts, these variants are NP-complete for general graphs. A graph G is H-free for some graph H if G contains no induced subgraph isomorphic to H. It is known that Connected Vertex Cover is NP-complete even for H-free graphs if H contains a claw or a cycle. We show that the two other connected variants also remain NP-complete if H contains a cycle or claw. In the remaining case H is a linear forest. We show that Connected Vertex Cover, Connected Feedback Vertex Set, and Connected Odd Cycle Transversal are polynomial-time solvable for sP2-free graphs for every constant s≥1. For proving these results we use known results on the price of connectivity for vertex cover, feedback vertex set, and odd cycle transversal. This is the first application of the price of connectivity that results in polynomial-time algorithms
Beyond Localized Environmental Contention: Horizontal and Vertical Diffusion in a Chinese Anti-Incinerator Campaign
Environmental contention is mounting all across China. In particular, protests against
environmentally hazardous construction projects have become a frequent phenomenon,
spreading well beyond China's major cities. While these protests are gaining growing
academic attention, they have mostly been analyzed as separate phenomena in isolation from
each other. Moreover, such grievance-based environmental contention has largely been
investigated separately from “environmentalist” activism underpinned by environmental
organizations and broader environmental concerns. Yet recent protest waves against the
construction of facilities such as waste incinerators and industrial facilities reveal the
emergence of linkages and diffusion processes between cases and actors that challenge
depictions of Chinese environmental contention as a necessarily purely localized and
parochial affair. This article examines this new development in Chinese environmental
activism through a detailed case study of an anti-incinerator campaign centered on a village in
Hebei Province. It shows how linkages emerged horizontally between local residents and
community activists involved in anti-incinerator campaigns elsewhere, and vertically between
villagers and members of China’s nascent “no burn” community, a group of actors highly
critical of waste incineration in China. We conclude that both types of linkages were crucial
for the development and success of the villagers’ campaign. Although opportunity for upward
scale-shift based on active intra-community collaboration remains highly constrained, vertical
ties and non-relational horizontal linkages ensure that the impact of environmental campaigns
reaches beyond the immediate localities in which they occur
Stochastic Quantization vs. KdV Flows in 2D Quantum Gravity
We consider the stochastic quantization scheme for a non-perturbative
stabilization of 2D quantum gravity and prove that it does not satisfy the KdV
flow equations. It therefore differs from a recently suggested matrix model
which allows real solutions to the KdV equations. The behaviour of the Fermi
energy, the free energy and macroscopic loops in the stochastic quantization
scheme are elucidated.Comment: 17 page
Trace elements in the nutrition and immunological response of grazing livestock
Sheep and cattle are complex biological factories. Outputs or
products from these factories may be meat, milk, wool, developing fetus,
etc. The inputs or raw products going into the system include oxygen,
water, carbohydrates, proteins, vitamins and minerals. Production can be
slowed down when any of the operating inputs is out of
balance.
Some minerals are required in relatively large amounts and are known
as the major elements. Others are required in much smaller amounts and
generally function in various enzymatic reactions in the body. Minerals in
this last group are referred to as trace elements and include cobalt (Co),
copper (Cu), iron (Fe), iodine (I), manganese (Mn), selenium (Se), zinc
(Zn), and molybdenum (Mo)
Non-Perturbative String Equations for Type 0A
Well-defined non-perturbative formulations of the physics of string theories,
sometimes with D-branes present, were identified over a decade ago, from a
careful study of double scaled matrix models. Following recent work which
recasts some of those old results in the context of type 0 string theory, a
study is made of a much larger family of models, which are proposed as type 0A
models of the entire superconformal minimal series coupled to gravity. This
gives many further examples of important physical phenomena, including
non-perturbative descriptions of transitions between D-branes and fluxes,
tachyon condensation, and holography. In particular, features of a large family
of non-perturbatively stable string equations are studied, and results are
extracted which pertain to type 0A string theory, with D-branes and fluxes, in
this large class of backgrounds. For the entire construction to work, large
parts of the spectrum of the supergravitationally dressed superconformal
minimal models and that of the gravitationally dressed bosonic conformal
minimal models must coincide, and it is shown how this happens. The example of
the super-dressed tricritical Ising model is studied in some detail.Comment: 29 pages LaTe
Simultaneous Embeddability of Two Partitions
We study the simultaneous embeddability of a pair of partitions of the same
underlying set into disjoint blocks. Each element of the set is mapped to a
point in the plane and each block of either of the two partitions is mapped to
a region that contains exactly those points that belong to the elements in the
block and that is bounded by a simple closed curve. We establish three main
classes of simultaneous embeddability (weak, strong, and full embeddability)
that differ by increasingly strict well-formedness conditions on how different
block regions are allowed to intersect. We show that these simultaneous
embeddability classes are closely related to different planarity concepts of
hypergraphs. For each embeddability class we give a full characterization. We
show that (i) every pair of partitions has a weak simultaneous embedding, (ii)
it is NP-complete to decide the existence of a strong simultaneous embedding,
and (iii) the existence of a full simultaneous embedding can be tested in
linear time.Comment: 17 pages, 7 figures, extended version of a paper to appear at GD 201
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