807 research outputs found
CODEX: mapping co-created data for speculative geographies
This paper discusses a series of artworks named CODEX produced by the authors as part of a collaborative research project between the Centre for Research in Education, Art and Media (CREAM), University of Westminster, and the Oxford Internet Institute. Taking the form of experimental maps, large-scale installations and prints, we show how big data can be employed to reflect upon social phenomena through the formulation of critical, aesthetic and speculative geographies
Exploring the relationship between groundwater geochemical factors and denitrification potentials on a dairy farm in southeast Ireland
NOTICE: this is the authorâs version of a work that was accepted for publication in the journal Ecological Engineering. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Ecological Engineering, volume 37, issue 9, September 2011, 1304-1313. DOI: 10.1016/j.ecoleng.2011.03.025peer-reviewedNitrate (NO3â) loss from agriculture to shallow groundwater and transferral to sensitive aquatic ecosystems is of global concern. Denitrifying bioreactor technology, where a solid carbon (C) reactive media intercepts contaminated groundwater, has been successfully used to convert NO3â to di-nitrogen (N2) gas. One of the challenges of groundwater remediation research is how to track denitrification potential spatially and temporally within reactive media and subsoil. First, using ÎŽ15N/ÎŽ18O isotopes, eight wells were divided into indicative transformational processes of ânitrificationâ or âdenitrificationâ wells. Then, using N2/argon (Ar) ratios these wells were divided into âlow denitrification potentialâ or high denitrification potentialâ categories. Secondly, using falling head tests, the saturated hydraulic conductivity (Ksat) in each well was estimated, creating two groups of âslowâ (0.06 m dayâ1) and âfastâ (0.13 m dayâ1) wells, respectively. Thirdly, two âlow denitrification potentialâ wells (one fast and one slow) with high NO3â concentration were amended with woodchip to enhance denitrification. Water samples were retrieved from all wells using a low flow syringe to avoid de-gassing and analysed for N2/Ar ratio using membrane inlet mass spectrometry. Results showed that there was good agreement between isotope and chemical (N2/Ar ratio and dissolved organic C (DOC)) and physio-chemical (dissolved oxygen, temperature, conductivity and pH) parameters. To explain the spatial and temporal distribution of NO3â and other parameters on site, the development of predictive models using the available datasets for this field site was examined for NO3â, Clâ, N2/Ar and DOC. Initial statistical analysis was directed towards the testing of the effect of woodchip amendment. The analysis was formulated as a repeated measures analysis of the factorial structure for treatment and time. Nitrate concentrations were related to Ksat and water level (p < 0.0001 and p = 0.02, respectively), but did not respond to woodchip addition (p = 0.09). This non-destructive technique allows elucidation of denitrification potential over time and could be used in denitrifying bioreactor technology to assess denitrification hotspots in reactive media, while developing a NO3â spatial and temporal predictive model for bioreactor site specific conditions
Teaching and understanding of quantum interpretations in modern physics courses
Just as expert physicists vary in their personal stances on interpretation in
quantum mechanics, instructors vary on whether and how to teach interpretations
of quantum phenomena in introductory modern physics courses. In this paper, we
document variations in instructional approaches with respect to interpretation
in two similar modern physics courses recently taught at the University of
Colorado, and examine associated impacts on student perspectives regarding
quantum physics. We find students are more likely to prefer realist
interpretations of quantum-mechanical systems when instructors are less
explicit in addressing student ontologies. We also observe contextual
variations in student beliefs about quantum systems, indicating that
instructors who choose to address questions of ontology in quantum mechanics
should do so explicitly across a range of topics.Comment: 18 pages, references, plus 2 pages supplemental materials. 8 figures.
PACS: 01.40.Fk, 03.65.-
Cyclone.soc: an interactive artwork visualizing Internet newsgroup postings as cyclonic weather conditions
Risk assessment of the use of alternative animal and plant raw material resources in aquaculture feeds
A wide range of raw materials are now used routinely in aquaculture feeds throughout the world, primarily to supply protein and energy in the form of lipid from edible oils. Protein meals and oils used can generally be divided into those of plant or animal origin and many have considerable potential to supply the required dietary nutrients required by aquaculture species. However, the use of any raw material introduces a suite of risks that need to be considered to enable the production of safe, sustainable and functional feeds to underpin this sector. A lack of understanding of some of those risks can result in failure of dietary specifications being met and/or negative nutritional elements being introduced (e.g. antinutritional factors). Importantly, it is this feed that when fed to foodâproducing animals is such an important element of food safety, and as such any undesirable aspects relating to feed production can also have a negative impact on the rest of the food chain. However, there is some disparity internationally among raw materials that are used and the perceptions surrounding the risk of their use. It is the scientific assessment of these risks that is the basis of this review
Evidence for Anisotropic Vortex Dynamics and Pauli Limitation in the Upper Critical Field of FeSe1-xTex
We have determined HC2(T) for FeSe1-xTex (x=0.52) single crystals using
resistivity measurements at high static and pulsed magnetic field, as well as
specific heat measurements up to 9T. We find that the significant anisotropy of
the initial slope of HC2(T) determined from resistivity measurements, is not
present when HC2 is determined from the specific heat results. This suggests
that the thermodynamic upper critical field is almost isotropic, and that
anisotropic vortex dynamics play a role. Further evidence of anisotropic vortex
dynamics is found in the behaviour in pulsed field. We also find that Pauli
limiting must be included in order to fit the temperature dependence of HC2,
indicating probably higher effective mass in FeSe1-xTex than in other Fe
superconductors
Tuberculosis prevalence survey in Kashmir valley
A tuberculosis prevalence survey was conducted in about 18,000 persons in
Kashmir valley situated about 1650 m above the mean sea level. All persons
were tested with 3 IU of PPD-S and 10 units of PPD-B. Persons aged 5 yr
and above were X-rayed (70 mm X-ray), and from such persons whose photofluorograms
were interpreted as abnormal two specimens of sputum were
collected and bacteriologically examined. In addition, a large X-ray of the
chest was taken for children aged 0-4 yr who had reactions of 10 mm or more
to PPD-S. They were then clinically examined by a paediatrician, taking into
account all available data, for evaluation for any evidence of tuberculosis.
The results of the survey showed that the prevalence of non-specific sensitivity
(59%) in the Kashmir valley is significant. The prevalence of tuberculous infection
was 38 per cent. The prevalence of culture positive tuberculous patients
(3 per 1000) and that of abacillary X-ray positive patients (14 per 1000) were
found to be similar in the two sexes contrary to the usual experience of a
higher prevalence among males. Results from studies of phage typing, susceptibility
to thiophen-2-carbonic acid hydrazide (TCH) and virulence in the
guineapig of strains obtained from patients diagnosed in the survey showed
that most of these strains belonged to phage type A, were resistant to TCH
and were not of low virulence. Regional variations in the prevalence rates
were seen, the- problem of tuberculosis appeared to he more in the Baramulla
district as compared to Srinagar and Anantnag districts. A comparison of results
obtained from the present survey with those obtained from the BCG trial
in Chingleput (Tamil Nadu) revealed that the tuberculosis situation in the
two areas was quite different
Evaluation of Roche Cobas Taqman Quantitative HIV-1 RNA PCR against other HIV-1 commercial viral load tests to examine potential under-quantification
Giant magnetothermopower of magnon-assisted transport in ferromagnetic tunnel junctions
We present a theoretical description of the thermopower due to
magnon-assisted tunneling in a mesoscopic tunnel junction between two
ferromagnetic metals. The thermopower is generated in the course of thermal
equilibration between two baths of magnons, mediated by electrons. For a
junction between two ferromagnets with antiparallel polarizations, the ability
of magnon-assisted tunneling to create thermopower depends on the
difference between the size of the majority and
minority band Fermi surfaces and it is proportional to a temperature dependent
factor where is the magnon Debye
energy. The latter factor reflects the fractional change in the net
magnetization of the reservoirs due to thermal magnons at temperature
(Bloch's law). In contrast, the contribution of magnon-assisted
tunneling to the thermopower of a junction with parallel polarizations is
negligible. As the relative polarizations of ferromagnetic layers can be
manipulated by an external magnetic field, a large difference results in a magnetothermopower effect. This
magnetothermopower effect becomes giant in the extreme case of a junction
between two half-metallic ferromagnets, .Comment: 9 pages, 4 eps figure
Biological methane production and accumulation under sulfate-rich conditions at Cape Lookout Bight, NC
IntroductionAnaerobic oxidation of methane (AOM) is hypothesized to occur through reverse hydrogenotrophic methanogenesis in marine sediments because sulfate reducers pull hydrogen concentrations so low that reverse hydrogenotrophic methanogenesis is exergonic. If true, hydrogenotrophic methanogenesis can theoretically co-occur with sulfate reduction if the organic matter is so labile that fermenters produce more hydrogen than sulfate reducers can consume, causing hydrogen concentrations to rise. Finding accumulation of biologically-produced methane in sulfate-containing organic-rich sediments would therefore support the theory that AOM occurs through reverse hydrogenotrophic methanogenesis since it would signal the absence of net AOM in the presence of sulfate.Methods16S rRNA gene libraries were compared to geochemistry and incubations in high depth-resolution sediment cores collected from organic-rich Cape Lookout Bight, North Carolina.ResultsWe found that methane began to accumulate while sulfate is still abundant (6â8âmM). Methane-cycling archaea ANME-1, Methanosarciniales, and Methanomicrobiales also increased at these depths. Incubations showed that methane production in the upper 16âcm in sulfate-rich sediments was biotic since it could be inhibited by 2-bromoethanosulfonoic acid (BES).DiscussionWe conclude that methanogens mediate biological methane production in these organic-rich sediments at sulfate concentrations that inhibit methanogenesis in sediments with less labile organic matter, and that methane accumulation and growth of methanogens can occur under these conditions as well. Our data supports the theory that H2 concentrations, rather than the co-occurrence of sulfate and methane, control whether methanogenesis or AOM via reverse hydrogenotrophic methanogenesis occurs. We hypothesize that the high amount of labile organic matter at this site prevents AOM, allowing methane accumulation when sulfate is low but still present in mM concentrations
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