242 research outputs found
Application of the European Regional Seas Ecosystem Model (ERSEM) to assessing the eutrophication status in the OSPAR Maritime Area, with particular reference to nutrient discharges from Scottish salmonid aquaculture
Aquaculture production of salmonids in Scotland has grown over the last 15 years, exceeded 150,000 tonnes in 2001. There have been conflicting views as to the likely ecological impact of nutrient discharges from this activity. Whilst quantitative assessments of aquaculture nutrient discharges have been carried out, the debate regarding possible eutrophication impacts of these discharges has so far been largely speculative. In order to provide a quantitative basis for this discussion, a marine ecosystem model was used to simulate the consequences of a 50% reduction in aquaculture nutrient discharges, and the results are presented here
Modelling the behaviour of nutrients in the coastal waters of Scotland
The overall goal of this project was to provide Scotland with a strategic ecosystem simulation tool for identifying maritime areas which could be at risk of eutrophication. The tool should provide spatially resolved output, and be capable of discriminating between different types and locations of nutrient inputs, so as to enable scenario analyses of different reduction options. The specific aims of the project were firstly to simulate the annual cycles of nutrients and ecological properties of Scottish waters and advise on areas which might suffer from eutrophication, and secondly, to determine the contribution of Scottish nutrient discharges to eutrophication in the OSPAR maritime area as a whole
Modelling the behaviour of nutrients in the coastal waters of Scotland - an update on inputs from Scottish aquaculture and their impact on eutrophication status
A previous study estimated that salmon farming contributed approximately 6% of Scotland's nitrogen-nutrient input to coastal waters, and 13% of phosphorus (based on 2001 production figures). However, in some areas of the west of Scotland with small freshwater catchment areas and low levels of human habitation, aquaculture inputs represented greater than 80% of the total. In 2002, FRS published results from an ecosystem modelling study involving a collaboration with the Institute for Marine Research, University of Hamburg, and the Macaulay Land Use Research Institute in Aberdeen, to assess the eutrophication impact of various nutrient inputs to Scottish waters. The results suggested that a 50% reduction in aquaculture salmon production would have only a small impact on water quality which would be undetectable against the background of natural variability due to climate variations. Estimating aquaculture nutrient discharge is a difficult task. The 2002 study was based on data relating to the consented biomass of fish at farm sites in sea lochs. Since then, new data have become available on the actual harvest of fish at all sites in Scotland. In this report, we re-assess the salmon production in Scotland in 2001 and the consequent nutrient discharge, and repeat the ecosystem model runs to estimate the impact of reduction scenarios on eutrophication status. The new data indicate that the previous study had overestimated salmon production and nutrient discharge by approximately 18% Scotland wide. Production and discharge at Shetland and in the Southern Hebrides had been under-estimated, whilst that in the Minches had been over-estimated. New runs of the ecosystem model show that the original conclusions on eutrophication impact were sound. A scenario of 50% reduction in salmon production produced regional changes in water quality which were less than 25% of the natural variability due to climate. New runs simulating a cessation of aquaculture showed that even this extreme reduction scenario produced changes in water quality that were less than half the natural variability
Disentangling habitat concepts for demersal marine fish management
Fishing and other anthropogenic impacts have led to declines in many fish stocks and modification of the seabed. As a result, efforts to restore marine ecosystems have become increasingly focused on spatially explicit management methods to protect fish and the habitats they require for survival. This has led to a proliferation of investigations trying to map ‘habitats’ vulnerable to anthropogenic impacts and identify fish resource requirements in order to meet conservation and management needs. A wide range of habitat-related concepts, with different uses and understandings of the word ‘habitat’ itself has arisen as a consequence. Inconsistencies in terminology can cause confusion between studies, making it difficult to investigate and understand the ecology of fish and the factors that affect their survival. Ultimately, the inability to discern the relationships between fish and their environment clearly can hinder conservation and management measures for fish populations. This review identifies and addresses the present ambiguity surrounding definitions of ‘habitat’ and habitat-related concepts currently used in spatial management of demersal marine fish populations. The role of spatial and temporal scales is considered, in addition to examples of how to assess fish habitat for conservation and management purposes
Fractal Nanotechnology
Self-similar patterns are frequently observed in Nature. Their reproduction is possible on a length scale 102–105 nm with lithographic methods, but seems impossible on the nanometer length scale. It is shown that this goal may be achieved via a multiplicative variant of the multi-spacer patterning technology, in this way permitting the controlled preparation of fractal surfaces
Observation of Scaling Violations in Scaled Momentum Distributions at HERA
Charged particle production has been measured in deep inelastic scattering
(DIS) events over a large range of and using the ZEUS detector. The
evolution of the scaled momentum, , with in the range 10 to 1280
, has been investigated in the current fragmentation region of the Breit
frame. The results show clear evidence, in a single experiment, for scaling
violations in scaled momenta as a function of .Comment: 21 pages including 4 figures, to be published in Physics Letters B.
Two references adde
D* Production in Deep Inelastic Scattering at HERA
This paper presents measurements of D^{*\pm} production in deep inelastic
scattering from collisions between 27.5 GeV positrons and 820 GeV protons. The
data have been taken with the ZEUS detector at HERA. The decay channel
(+ c.c.) has been used in the study. The
cross section for inclusive D^{*\pm} production with
and is 5.3 \pms 1.0 \pms 0.8 nb in the kinematic region
{ GeV and }. Differential cross
sections as functions of p_T(D^{*\pm}), and are
compared with next-to-leading order QCD calculations based on the photon-gluon
fusion production mechanism. After an extrapolation of the cross section to the
full kinematic region in p_T(D^{*\pm}) and (D^{*\pm}), the charm
contribution to the proton structure function is
determined for Bjorken between 2 10 and 5 10.Comment: 17 pages including 4 figure
Observation of hard scattering in photoproduction events with a large rapidity gap at HERA
Events with a large rapidity gap and total transverse energy greater than 5
GeV have been observed in quasi-real photoproduction at HERA with the ZEUS
detector. The distribution of these events as a function of the
centre of mass energy is consistent with diffractive scattering. For total
transverse energies above 12 GeV, the hadronic final states show predominantly
a two-jet structure with each jet having a transverse energy greater than 4
GeV. For the two-jet events, little energy flow is found outside the jets. This
observation is consistent with the hard scattering of a quasi-real photon with
a colourless object in the proton.Comment: 19 pages, latex, 4 figures appended as uuencoded fil
Solar parameters for modeling interplanetary background
The goal of the Fully Online Datacenter of Ultraviolet Emissions (FONDUE)
Working Team of the International Space Science Institute in Bern, Switzerland,
was to establish a common calibration of various UV and EUV heliospheric
observations, both spectroscopic and photometric. Realization of this goal
required an up-to-date model of spatial distribution of neutral interstellar
hydrogen in the heliosphere, and to that end, a credible model of the radiation
pressure and ionization processes was needed. This chapter describes the solar
factors shaping the distribution of neutral interstellar H in the heliosphere.
Presented are the solar Lyman-alpha flux and the solar Lyman-alpha resonant
radiation pressure force acting on neutral H atoms in the heliosphere, solar
EUV radiation and the photoionization of heliospheric hydrogen, and their
evolution in time and the still hypothetical variation with heliolatitude.
Further, solar wind and its evolution with solar activity is presented in the
context of the charge exchange ionization of heliospheric hydrogen, and in the
context of dynamic pressure variations. Also the electron ionization and its
variation with time, heliolatitude, and solar distance is presented. After a
review of all of those topics, we present an interim model of solar wind and
the other solar factors based on up-to-date in situ and remote sensing
observations of solar wind. Results of this effort will further be utilised to
improve on the model of solar wind evolution, which will be an invaluable asset
in all heliospheric measurements, including, among others, the observations of
Energetic Neutral Atoms by the Interstellar Boundary Explorer (IBEX).Comment: Chapter 2 in the planned "Cross-Calibration of Past and Present Far
UV Spectra of Solar System Objects and the Heliosphere", ISSI Scientific
Report No 12, ed. R.M. Bonnet, E. Quemerais, M. Snow, Springe
Timing of Radiotherapy (RT) after Radical Prostatectomy (RP): Long-term outcomes in the RADICALS-RT trial [NCT00541047]
Background
The optimal timing of radiotherapy (RT) after radical prostatectomy for prostate cancer has been uncertain. RADICALS-RT compared efficacy and safety of adjuvant RT versus an observation policy with salvage RT for PSA failure.
Methods
RADICALS-RT was a randomised controlled trial enrolling patients with ≥1 risk factor (pT3/4, Gleason 7-10, positive margins, pre-op PSA≥10ng/ml) for recurrence after radical prostatectomy. Patients were randomised 1:1 to adjuvant RT (“Adjuvant-RT”) or an observation policy with salvage RT for PSA failure (“Salvage-RT”) defined as PSA≥0.1ng/ml or 3 consecutive rises. Stratification factors were Gleason score, margin status, planned RT schedule (52.5Gy/20 fractions or 66Gy/33 fractions) and treatment centre. The primary outcome measure was freedom-from-distant metastasis, designed with 80% power to detect an improvement from 90% with Salvage-RT (control) to 95% at 10yr with Adjuvant-RT. Secondary outcome measures were bPFS, freedom-from-non-protocol hormone therapy, safety and patient-reported outcomes. Standard survival analysis methods were used; HR<1 favours Adjuvant-RT.
Findings
Between Oct-2007 and Dec-2016, 1396 participants from UK, Denmark, Canada and Ireland were randomised: 699 Salvage-RT, 697 Adjuvant-RT. Allocated groups were balanced with median age 65yr. 93% (649/697) Adjuvant-RT reported RT within 6m after randomisation; 39% (270/699) Salvage-RT reported RT during follow-up. Median follow-up was 7.8 years. With 80 distant metastasis events, 10yr FFDM was 93% for Adjuvant-RT and 90% for Salvage-RT: HR=0.68 (95%CI 0·43–1·07, p=0·095). Of 109 deaths, 17 were due to prostate cancer. Overall survival was not improved (HR=0.980, 95%CI 0.667–1.440, p=0.917). Adjuvant-RT reported worse urinary and faecal incontinence one year after randomisation (p=0.001); faecal incontinence remained significant after ten years (p=0.017).
Interpretation
Long-term results from RADICALS-RT confirm adjuvant RT after radical prostatectomy increases the risk of urinary and bowel morbidity, but does not meaningfully improve disease control. An observation policy with salvage RT for PSA failure should be the current standard after radical prostatectomy
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