311 research outputs found
EU Water Framework Directive : groundwater-dependent rivers and lakes in Northern Ireland
The EU Water Framework Directive (WFD) requires that those rivers and lakes that are
dependent on groundwater be identified and the pressures on these analysed such that the risk of
not meeting their environmental objectives by 2015, as set out in Article 4, can be assessed. This
report describes the methodology for identifying and carrying out risk assessments for
groundwater-dependent rivers and lakes in Northern Ireland, as part of the initial characterisation
process. The methodology reflects UK Technical Advisory Group (UKTAG) guidance.
The report details those river water bodies and lakes that are groundwater dependent and
assesses which of these are at risk of being significantly damaged as a result of groundwater
abstractions and potentially polluting point sources; diffuse pollution is addressed elsewhere.
The report does not address quantitative impacts on rivers and lakes from groundwater
abstractions outside specified assessment zones; the study addressed localised impacts rather
than those due to cumulative groundwater abstractions which affect the overall groundwater
body water balance, and the âavailable groundwater resourceâ. This is reported elsewhere.
The risk assessment for lakes has been restricted to those with an area greater than 50 hectares,
these being the reporting units agreed for the UK for initial characterisation. Lough Neagh and
Upper and Lower Lough Erne, whilst obviously falling within this category due to their
significant scale, are reported elsewhere.
Of the 673 river water bodies considered, 564 are classified as groundwater dependent. Of the
17 lakes assessed, 10 are classified as groundwater dependent.
None of the groundwater-dependent lakes are assessed as being affected by groundwater
abstractions. Flows in four river water bodies are possibly at local risk due to groundwater
abstractions, and one, the Breckagh Burn, is probably at risk.
All groundwater-dependent lakes have been classified as risk category 2b in relation to
potentially polluting point sources. Using an approach that assesses the equivalent categories for
river water bodies based on the sum of the number of sources within the surrounding assessment
zones, regardless of type, 113 river water bodies were classified as risk category 2a and the
remainder risk category 2b.
The report details data limitations and gaps in knowledge affecting the initial characterisation
process used
Forestry plantations as a pathway for invasive alien plants in the National Park at RĂ©union island
Identifying pathways of introduction remains a major priority to prevent future plant invasions into natural areas. In this study, we assessed whether forestry plantations favor alien plant dissemination into the National Park of Reunion. Results showed significant decrease in the percentage of alien plant biomass from the forestry plantations to the undisturbed areas. At one site, a significant difference was also found for the mean alien species number and the mean alien plant abundance. In both sites, numerous alien species were present in the understorey of Cryptomeria plantations only, with some already escaping and occurring at the entrance of the National Park. This study recommends strengthening early detection and rapid response of alien plants and suggests alternative management approaches in forestry plantations, including the use of community-based restoration programmes.Une des prioritĂ©s pour contrĂŽler les futures invasions floristiques est dâidentifier les voies dâintroduction aux abords des aires naturelles. Dans cette Ă©tude, nous avons testĂ© si les forĂȘts cultivĂ©es peuvent favoriser lâenvahissement par les plantes exotiques Ă lâintĂ©rieur du Parc national de la RĂ©union. Les rĂ©sultats montrent une diminution significative du pourcentage de la biomasse vĂ©gĂ©tale des plantes exotiques des forĂȘts cultivĂ©es vers le milieu naturel. Les diffĂ©rences sont Ă©galement significatives au niveau dâun des deux sites Ă©tudiĂ©s concernant les moyennes du nombre de plantes exotiques et de la somme de lâabondance des plantes. Dans les deux cas, de nombreuses espĂšces sont prĂ©sentes seulement en sous-bois de forĂȘts cultivĂ©es ou Ă©galement Ă lâentrĂ©e du Parc national. Cette Ă©tude prĂ©conise de renforcer les actions de dĂ©tection prĂ©coce et de rĂ©ponse rapide. Les auteurs proposent Ă©galement la mise en place de mĂ©thodes de gestion alternatives de ces habitats incluant une approche participative de la population dans des programmes de restauration
Forestry plantations as a pathway for invasive alien plants in the National Park at RĂ©union island
Identifying pathways of introduction remains a major priority to prevent future plant invasions into natural areas. In this study, we assessed whether forestry plantations favor alien plant dissemination into the National Park of Reunion. Results showed significant decrease in the percentage of alien plant biomass from the forestry plantations to the undisturbed areas. At one site, a significant difference was also found for the mean alien species number and the mean alien plant abundance. In both sites, numerous alien species were present in the understorey of Cryptomeria plantations only, with some already escaping and occurring at the entrance of the National Park. This study recommends strengthening early detection and rapid response of alien plants and suggests alternative management approaches in forestry plantations, including the use of community-based restoration programmes.Une des prioritĂ©s pour contrĂŽler les futures invasions floristiques est dâidentifier les voies dâintroduction aux abords des aires naturelles. Dans cette Ă©tude, nous avons testĂ© si les forĂȘts cultivĂ©es peuvent favoriser lâenvahissement par les plantes exotiques Ă lâintĂ©rieur du Parc national de la RĂ©union. Les rĂ©sultats montrent une diminution significative du pourcentage de la biomasse vĂ©gĂ©tale des plantes exotiques des forĂȘts cultivĂ©es vers le milieu naturel. Les diffĂ©rences sont Ă©galement significatives au niveau dâun des deux sites Ă©tudiĂ©s concernant les moyennes du nombre de plantes exotiques et de la somme de lâabondance des plantes. Dans les deux cas, de nombreuses espĂšces sont prĂ©sentes seulement en sous-bois de forĂȘts cultivĂ©es ou Ă©galement Ă lâentrĂ©e du Parc national. Cette Ă©tude prĂ©conise de renforcer les actions de dĂ©tection prĂ©coce et de rĂ©ponse rapide. Les auteurs proposent Ă©galement la mise en place de mĂ©thodes de gestion alternatives de ces habitats incluant une approche participative de la population dans des programmes de restauration
Do Clinical Guidelines for Whole Body Computerised Tomography in Trauma Improve Diagnostic Accuracy and Reduce Unnecessary Investigations? A Systematic Review and Narrative Synthesis.
Introduction
Whole body computerised tomography has become a standard of care for the investigation of major trauma patients. However, its use varies widely, and current clinical guidelines are not universally accepted. We undertook a systematic review of the literature to determine whether clinical guidelines for whole body computerised tomography in trauma increase its diagnostic accuracy.
Materials and methods
A systematic review of Medline, Cinhal and the Cochrane database, supplemented by a manual search of relevant papers was undertaken, with narrative synthesis. Studies comparing clinical guidelines to physician gestalt for the use of whole body computerised tomography in adult trauma were included.
Results
A total of 887 papers were identified from the electronic databases, and 1 from manual searches. Of these, seven papers fulfilled the inclusion criteria. Two papers compared clinical guidelines with routine practice: one found increased diagnostic accuracy while the other did not. Two papers investigated the performance of established clinical guidelines and demonstrated moderate sensitivity and low specificity. Two papers compared different components of established triage tools in trauma. One paper devised a de novo clinical decision rule, and demonstrated good diagnostic accuracy with the tool. The outcome criteria used to define a âpositiveâ scan varied widely, making direct comparisons between studies impossible.
Conclusions
Current clinical guidelines for whole body computerised tomography in trauma may increase the sensitivity of the investigation, but the evidence to support this is limited. There is a need to standardise the definition of a âclinically significantâ finding on CT to allow better comparison of diagnostic studies
Gemini/GMOS Transmission Spectroscopy of the Grazing Planet Candidate WD 1856+534 b
WD 1856+534 b is a Jupiter-sized, cool giant planet candidate transiting the white dwarf WD 1856+534. Here, we report an optical transmission spectrum of WD 1856+534 b obtained from ten transits using the Gemini Multi-Object Spectrograph. This system is challenging to observe due to the faintness of the host star and the short transit duration. Nevertheless, our phase-folded white light curve reached a precision of 0.12%. WD 1856+534 b provides a unique transit configuration compared to other known exoplanets: the planet is 8 larger than its star and occults over half of the stellar disk during mid-transit. Consequently, many standard modeling assumptions do not hold. We introduce the concept of a "limb darkening corrected, time-averaged transmission spectrum"and propose that this is more suitable than for comparisons to atmospheric models for planets with grazing transits. We also present a modified radiative transfer prescription. Though the transmission spectrum shows no prominent absorption features, it is sufficiently precise to constrain the mass of WD 1856+534 b to be >0.84 M J (to 2Ï confidence), assuming a clear atmosphere and a Jovian composition. High-altitude cloud decks can allow lower masses. WD 1856+534 b could have formed either as a result of common envelope evolution or migration under the Kozai-Lidov mechanism. Further studies of WD 1856+534 b, alongside new dedicated searches for substellar objects around white dwarfs, will shed further light on the mysteries of post-main-sequence planetary systems
Upper critical field for underdoped high-T_c superconductors. Pseudogap and stripe--phase
We investigate the upper critical field in a stripe--phase and in the
presence of a phenomenological pseudogap. Our results indicate that the
formation of stripes affects the Landau orbits and results in an enhancement of
. On the other hand, phenomenologically introduced pseudogap leads to a
reduction of the upper critical field. This effect is of particular importance
when the magnitude of the gap is of the order of the superconducting transition
temperature. We have found that a suppression of the upper critical field takes
place also for the gap that originates from the charge--density waves.Comment: 7 pages, 5 figure
Tomonaga-Luttinger parameters for quantum wires
The low-energy properties of a homogeneous one-dimensional electron system
are completely specified by two Tomonaga-Luttinger parameters and
. In this paper we discuss microscopic estimates of the values of
these parameters in semiconductor quantum wires that exploit their relationship
to thermodynamic properties. Motivated by the recognized similarity between
correlations in the ground state of a one-dimensional electron liquid and
correlations in a Wigner crystal, we evaluate these thermodynamic quantities in
a self-consistent Hartree-Fock approximation. According to our calculations,
the Hartree-Fock approximation ground state is a Wigner crystal at all electron
densities and has antiferromagnetic order that gradually evolves from
spin-density-wave to localized in character as the density is lowered. Our
results for are in good agreement with weak-coupling perturbative
estimates at high densities, but deviate strongly at low
densities, especially when the electron-electron interaction is screened at
long distances. vanishes at small carrier density
whereas we conjecture that when , implying that
should pass through a minimum at an intermediate density.
Observation of such a non-monotonic dependence on particle density would allow
to measure the range of the microscopic interaction. In the spin sector we find
that the spin velocity decreases with increasing interaction strength or
decreasing . Strong correlation effects make it difficult to obtain fully
consistent estimates of from Hartree-Fock calculations. We
conjecture that v_{\sigma}/\vf\propto n/V_0 in the limit where
is the interaction strength.Comment: RevTeX, 23 pages, 8 figures include
25th-order high-temperature expansion results for three-dimensional Ising-like systems on the simple cubic lattice
25th-order high-temperature series are computed for a general
nearest-neighbor three-dimensional Ising model with arbitrary potential on the
simple cubic lattice. In particular, we consider three improved potentials
characterized by suppressed leading scaling corrections. Critical exponents are
extracted from high-temperature series specialized to improved potentials,
obtaining , , ,
, , . Moreover, biased
analyses of the 25th-order series of the standard Ising model provide the
estimate for the exponent associated with the leading scaling
corrections. By the same technique, we study the small-magnetization expansion
of the Helmholtz free energy. The results are then applied to the construction
of parametric representations of the critical equation of state, using a
systematic approach based on a global stationarity condition. Accurate
estimates of several universal amplitude ratios are also presented.Comment: 40 pages, 15 figure
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