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

Integration and Conventional Systems at STAR

At the beginning of the design and construction of the STAR Detector, the collaboration assigned a team of physicists and engineers the responsibility of coordinating the construction of the detector. This group managed the general space assignments for each sub-system and coordinated the assembly and planning for the detector. Furthermore, as this group was the only STAR group with the responsibility of looking at the system as a whole, the collaboration assigned it several tasks that spanned the different sub-detectors. These items included grounding, rack layout, cable distribution, electrical, power and water, and safety systems. This paper describes these systems and their performance.Comment: 17 pages, 6 figures, Contribution to a NIM Volume Dedicated to the Detectors and the Accelerator at RHI

Parity nonconservation in heavy atoms: The radiative correction enhanced by the strong electric field of the nucleus

Parity nonconservation due to the nuclear weak charge is considered. We demonstrate that the radiative corrections to this effect due to the vacuum fluctuations of the characteristic size larger than the nuclear radius $r_0$ and smaller than the electron Compton wave-length $\lambda_C$ are enhanced because of the strong electric field of the nucleus. The parameter that allows one to classify the corrections is the large logarithm $\ln(\lambda_C/r_0)$. The vacuum polarization contribution is enhanced by the second power of the logarithm. Although the self-energy and the vertex corrections do not vanish, they contain only the first power of the logarithm. The value of the radiative correction is 0.4% for Cs and 0.9% for Tl, Pb, and Bi. We discuss also how the correction affects the interpretation of the experimental data on parity nonconservation in atoms.Comment: 4 pages, 3 figures, RevTe

Bcc 4^4He as a Coherent Quantum Solid

In this work we investigate implications of the quantum nature of bcc $^{4}$% He. We show that it is a unique solid phase with both a lattice structure and an Off-Diagonal Long Range Order of coherently oscillating local electric dipole moments. These dipoles arise from the local motion of the atoms in the crystal potential well, and oscillate in synchrony to reduce the dipolar interaction energy. The dipolar ground-state is therefore found to be a coherent state with a well defined global phase and a three-component complex order parameter. The condensation energy of the dipoles in the bcc phase stabilizes it over the hcp phase at finite temperatures. We further show that there can be fermionic excitations of this ground-state and predict that they form an optical-like branch in the (110) direction. A comparison with 'super-solid' models is also discussed.Comment: 12 pages, 8 figure

The Weak Charge of the Proton and New Physics

We address the physics implications of a precision determination of the weak charge of the proton, QWP, from a parity violating elastic electron proton scattering experiment to be performed at the Jefferson Laboratory. We present the Standard Model (SM) expression for QWP including one-loop radiative corrections, and discuss in detail the theoretical uncertainties and missing higher order QCD corrections. Owing to a fortuitous cancellation, the value of QWP is suppressed in the SM, making it a unique place to look for physics beyond the SM. Examples include extra neutral gauge bosons, supersymmetry, and leptoquarks. We argue that a QWP measurement will provide an important complement to both high energy collider experiments and other low energy electroweak measurements. The anticipated experimental precision requires the knowledge of the order alpha_s corrections to the pure electroweak box contributions. We compute these contributions for QWP, as well as for the weak charges of heavy elements as determined from atomic parity violation.Comment: 22 pages of LaTeX, 5 figure

Reevaluation of the role of nuclear uncertainties in experiments on atomic parity violation with isotopic chains

In light of new data on neutron distributions from experiments with antiprotonic atoms [ Trzcinska {\it et al.}, Phys. Rev. Lett. 87, 082501 (2001)], we reexamine the role of nuclear-structure uncertainties in the interpretation of measurements of parity violation in atoms using chains of isotopes of the same element. With these new nuclear data, we find an improvement in the sensitivity of isotopic chain measurements to ``new physics'' beyond the standard model. We compare possible constraints on ``new physics'' with the most accurate to date single-isotope probe of parity violation in the Cs atom. We conclude that presently isotopic chain experiments employing atoms with nuclear charges Z < 50 may result in more accurate tests of the weak interaction.Comment: 6 pages, 1 fig., submitted to Phys. Rev.

The STAR Time Projection Chamber: A Unique Tool for Studying High Multiplicity Events at RHIC

The STAR Time Projection Chamber (TPC) is used to record collisions at the Relativistic Heavy Ion Collider (RHIC). The TPC is the central element in a suite of detectors that surrounds the interaction vertex. The TPC provides complete coverage around the beam-line, and provides complete tracking for charged particles within +- 1.8 units of pseudo-rapidity of the center-of-mass frame. Charged particles with momenta greater than 100 MeV/c are recorded. Multiplicities in excess of 3,000 tracks per event are routinely reconstructed in the software. The TPC measures 4 m in diameter by 4.2 m long, making it the largest TPC in the world.Comment: 28 pages, 11 figure

Measurement of the Decay Asymmetry Parameters in Λc+→Λπ+\Lambda_c^+ \to \Lambda\pi^+ and Λc+→Σ+π0\Lambda_c^+ \to \Sigma^+\pi^0

We have measured the weak decay asymmetry parameters (\aLC ) for two \LC\ decay modes. Our measurements are \aLC = -0.94^{+0.21+0.12}_{-0.06-0.06} for the decay mode $\Lambda_c^+ \to \Lambda\pi^+$ and \aLC = -0.45\pm 0.31 \pm 0.06 for the decay mode $\Lambda_c \to \Sigma^+\pi^0$. By combining these measurements with the previously measured decay rates, we have extracted the parity-violating and parity-conserving amplitudes. These amplitudes are used to test models of nonleptonic charmed baryon decay.Comment: 11 pages including the figures. Uses REVTEX and psfig macros. Figures as uuencoded postscript. Also available as http://w4.lns.cornell.edu/public/CLNS/1995/CLNS95-1319.p