684 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

    Get PDF
    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

    Get PDF
    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

    Get PDF
    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

    Full text link
    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

    Gas turbine engine condition monitoring using Gaussian mixture and hidden Markov models

    Get PDF
    This paper investigates the problem of condition monitoring of complex dynamic systems, specifically the detection, localisation and quantification of transient faults. A data driven approach is developed for fault detection where the multidimensional data sequence is viewed as a stochastic process whose behaviour can be described by a hidden Markov model with two hidden states --- i.e. `healthy / nominal' and `unhealthy / faulty'. The fault detection is performed by first clustering in a multidimensional data space to define normal operating behaviour using a Gaussian-Uniform mixture model. The health status of the system at each data point is then determined by evaluating the posterior probabilities of the hidden states of a hidden Markov model. This allows the temporal relationship between sequential data points to be incorporated into the fault detection scheme. The proposed scheme is robust to noise and requires minimal tuning. A real-world case study is performed based on the detection of transient faults in the variable stator vane actuator of a gas turbine engine to demonstrate the successful application of the scheme. The results are used to demonstrate the generation of simple and easily interpretable analytics that can be used to monitor the evolution of the fault across time

    Mass probation: Temporal and geographic correlation of county-level probation rates & mental health in North Carolina

    Get PDF
    High community incarceration rates are associated with worse community mental health. However, it remains unknown whether higher rates of probation, a form of criminal legal community supervision, are similarly associated with worse community mental health. Our objective was to evaluate temporal and geographic correlations of county-level probation and mental health rates separately and to assess the association between county-level probation and mental health rates, measured by self-inflicted injury and suicide. We performed ecological analyses using North Carolina administrative data (2009–2019) and used repeated cross-section, multivariable spatial error models. From 2009 to 2019, probation rates trended downward while self-inflicted injury and suicide remained stable. We found positive spatial autocorrelation suggesting that there are spatial determinants of probation and self-harm, though less so for suicide. Hot spot analyses showed local variation with high self-harm and suicide rates being clustered in rural Western North Carolina and high probation rates being clustered in rural Eastern North Carolina. Probation was positively associated with self-inflicted injury and suicide. For example, in 2018, a 1 percentage point increase in probation was associated with a 0.05 percentage point increase in self-harm in 2019 (95% CI: 0.03, 0.06), meaning that in a county of 100,000 people, an increase in 1000 county residents being on probation would be associated with an increase in 50 self-harm injuries. High county-level probation rates may exert collateral damage on the mental health of those living in areas with much of the population under state control. These findings emphasize that the criminal legal system is not separate from communities and that future public health research and advocacy must consider these collateral consequences of probation on communities

    Bcc 4^4He as a Coherent Quantum Solid

    Full text link
    In this work we investigate implications of the quantum nature of bcc 4^{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

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

    Full text link
    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 r0r_0 and smaller than the electron Compton wave-length λC\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(λC/r0)\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

    Inequities in life course criminal legal system sanctions: measuring cumulative involvement

    Get PDF
    Purpose: The impact of incarceration on health is well known. Yet, most studies measure incarceration alone and miss additional exposure to the criminal legal system over time. We evaluated adult criminal legal sanctions – inclusive of arrests, charges, probation, incarceration – from ages 18–35 and inequities by juvenile sanctions and race. Methods: Using the National Longitudinal Survey on Youth 1997, a nationally representative data set of adolescents followed into their mid-thirties (1997–2017), we calculated the mean cumulative count, or the average number of criminal legal events per person per study visit, stratified by juvenile sanctions and race. Results: Of 7024 participants, 1679 experienced 3,075 encounters. There were seven arrests, 30 charges, nine probation encounters, and 13 incarceration events /100 participants by age 35. Juvenile sanctions were most common for Black individuals. Among those experiencing juvenile sanctions, Black and White individuals had similar numbers of encounters, but Black individuals had more arrests and incarceration stays. For those without juvenile encounters, Black individuals had more encounters than White individuals. Conclusions: Research on health effects of criminal legal sanctions must consider encounters beyond incarceration and focus on life course trajectories and racial inequities

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

    Get PDF
    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.
    corecore