326 research outputs found

    Community implementation dynamics: Nutrient management in the New York City and Chesapeake Bay Watersheds

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    The creation of natural resource management and conservation strategies can be affected by engagement with local citizens and competing interests between agencies and stakeholders at the varying levels of governance. This paper examines the role of local engagement and the interaction between governance levels on the outcomes of nutrient management policy, a specific area of natural resource conservation and management. Presented are two case studies of the New York City and Chesapeake Bay Watersheds in the US. These case studies touch upon the themes of local citizen engagement and governance stakeholder interaction in changing nutrient management to improve water quality. An analysis of these cases leads to several key considerations for the creation and implementation of nutrient management and natural resource management more broadly, including the importance of: local citizen engagement, government brokering and cost sharing; and the need of all stakeholders to respect each other in the policy creation and implementation process

    Valuing Transgenic Cotton Technologies Using a Risk/Return Framework

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    Stochastic Efficiency with Respect to a Function (SERF) is used to rank transgenic cotton technology groups and place an upper and lower bound on their value. Yield and production data from replicated plot experiments are used to build cumulative distribution functions of returns for nontransgenic, Roundup Ready, Bollgard, and stacked gene cotton cultivars. Analysis of Arkansas data indicated that the stacked gene and Roundup Ready technologies would be preferred by a large number of risk neutral and risk averse producers as long as the costs of the technology and seed are below the lower bounds calculated in this manuscript.cotton, financial risk, market value, SERF, transgenic, Agribusiness, Crop Production/Industries, Risk and Uncertainty, Q12, Q16,

    Conserved currents and gauge invariance in Yang-Mills theory

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    It is shown that in the absence of free abelian gauge fields, the conserved currents of (classical) Yang-Mills gauge models coupled to matter fields can be always redefined so as to be gauge invariant. This is a direct consequence of the general analysis of the Wess-Zumino consistency condition for Yang-Mills theory that we have provided recently.Comment: 12 pages, latex, no figures, version to appear in Phys. Lett.

    Surface charges and dynamical Killing tensors for higher spin gauge fields in constant curvature spaces

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    In the context of massless higher spin gauge fields in constant curvature spaces, we compute the surface charges which generalize the electric charge for spin one, the color charges in Yang-Mills theories and the energy-momentum and angular momentum for asymptotically flat gravitational fields. We show that there is a one-to-one map from surface charges onto divergence free Killing tensors. These Killing tensors are computed by relating them to a cohomology group of the first quantized BRST model underlying the Fronsdal action.Comment: 21 pages Latex file, references and comment adde

    Economic Values for Perennial Ryegrass Traits in New Zealand Dairy Farm Systems

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    Perennial ryegrass (Lolium perenne L.) is the main species used in dairy pastures throughout New Zealand. There are approximately 30 perennial ryegrass cultivars sold commercially in New Zealand, but currently there is no evaluation system which allows farmers to compare the potential impact of different cultivars on the profitability of their farm business. Such an economic evaluation system requires information on performance values (PV) for cultivars which quantifies their performance with respect to the major productivity traits (herbage accumulation (HA, kg DM/ha), nutritive value and persistence) relative to a genetic base, and economic values (EV, Doyle and Elliott 1983) which estimate the additional profit resulting from each unit change in the trait of interest (Equation 1). Economic value = Δ operating profit/Δ trait of interest (1) This paper describes a system modelling approach developed to estimate EV for seasonal HA of pasture in the major dairying regions of New Zealand. This information is used in the DairyNZ Forage Value Index system (www.dairynzfvi.co.nz) which is being developed to include information on all three productivity traits for commercially available ryegrass cultivars

    Development of a Forage Evaluation System for Perennial Ryegrass Cultivar and Endophyte Combinations in New Zealand Dairy Systems

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    An economic index for perennial ryegrass (Lolium perenne L.) cultivars is a relatively new concept, although recently introduced in Ireland (McEvoy et al. 2011). By contrast, in dairy cattle breeding, the concept of an economic index rating animals and economic values underlying that index is well entrenched (Philipson et al. 1994; Veerkamp, 1998). Historically, forage evaluation data for individual cultivars were either displayed using absolute numbers for seasonal dry matter production within a season or across all seasons with a notation to indicate statistical differences, or percentage values where a reference cultivar is 100. The adoption of an economic index and routine evaluation approach for perennial ryegrass provides a method to identify traits of economic importance to focus plant breeding efforts better and to provide clarity for farmers around predicting cultivars that will maximise farm profit. It also allows for routine tracking of genetic gain of individual traits and the economic index. In this paper, the economic based forage evaluation techniques now used in New Zealand for perennial ryegrass cultivar/endophyte combinations are presented

    Nonsuicidal Self-Injury, Suicide Planning, and Suicide Attempt Among High-Risk Adolescents Prior to Psychiatric Hospitalization

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    The purpose of this study was to understand the trajectories of nonsuicidal self-injury (NSSI) and suicide plans (SP) in the 90 days prior to inpatient hospitalization, understand the role of NSSI and SP in predicting suicide attempts (SA) on a given day, and to test the interaction between NSSI and SP in predicting same-day SA. Participants included 69 adolescents (77% female, 65% white, 77% Non-Hispanic/Latinx, Mage = 15.77 SDage = 1.00) from an inpatient psychiatric unit. Past 90 day NSSI, SP, and SA were measured using the Columbia Suicide Severity Rating Scale and Timeline Follow Back. First, mixed effect models were conducted to assess trajectories of NSSI and SP leading up to inpatient hospitalization. The odds of NSSI remained relatively stable prior to hospitalization (OR = 1.01, 95% CI [1.00,1.02]). The odds of SP increased in the 90 days prior to hospitalization (OR = 1.04, 95% CI [1.02,1.05]) with each day associated with a 4% increase in the odds of making a SP. Second, random effect models were conducted to predict the odds of same-day SA from NSSI and SP. When adolescents endorsed either NSSI (OR = 2.99, p \u3c .001) or a SP (OR = 77.13, p \u3c .001) there was elevated odds of same-day SA. However, the presence of both NSSI and SP on a given day did not increase risk of SA on that same day. For this high-risk clinical sample of suicidal adolescents who drink alcohol, odds of SP increased in the days leading up to psychiatric hospitalization, but NSSI remained stable. On days when adolescents reported NSSI or SP, they had an increased odds of same-day SA. These results underscore the importance of frequent monitoring of NSSI and SP among high-risk adolescents who drink alcohol to prevent suicide attempts

    Local BRST cohomology in Einstein--Yang--Mills theory

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    We analyse in detail the local BRST cohomology in Einstein-Yang-Mills theory using the antifield formalism. We do not restrict the Lagrangian to be the sum of the standard Hilbert and Yang-Mills Lagrangians, but allow for more general diffeomorphism and gauge invariant actions. The analysis is carried out in all spacetime dimensions larger than 2 and for all ghost numbers. This covers the classification of all candidate anomalies, of all consistent deformations of the action, as well as the computation of the (equivariant) characteristic cohomology, i.e. the cohomology of the spacetime exterior derivative in the space of (gauge invariant) local differential forms modulo forms that vanish on-shell. We show in particular that for a semi-simple Yang-Mills gauge group the antifield dependence can be entirely removed both from the consistent deformations of the Lagrangian and from the candidate anomalies. Thus, the allowed deformations of the action necessarily preserve the gauge structure, while the only candidate anomalies are those provided by previous works not dealing with antifields, and by ``topological" candidate anomalies which are present only in special spacetime dimensions (6,9,10,13,...). This result no longer holds in presence of abelian factors where new candidate anomalies and deformations of the action can be constructed out of the conserved Noether currents (if any). The Noether currents themselves are shown to be covariantizable, with a few exceptions discussed as well.Comment: 68 pages, latex, no figures Misprint corrected in list of dimensions where topological anomalies can occur (no such anomaly in 11 dimensions

    Covariant theory of asymptotic symmetries, conservation laws and central charges

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    Under suitable assumptions on the boundary conditions, it is shown that there is a bijective correspondence between equivalence classes of asymptotic reducibility parameters and asymptotically conserved n-2 forms in the context of Lagrangian gauge theories. The asymptotic reducibility parameters can be interpreted as asymptotic Killing vector fields of the background, with asymptotic behaviour determined by a new dynamical condition. A universal formula for asymptotically conserved n-2 forms in terms of the reducibility parameters is derived. Sufficient conditions for finiteness of the charges built out of the asymptotically conserved n-2 forms and for the existence of a Lie algebra g among equivalence classes of asymptotic reducibility parameters are given. The representation of g in terms of the charges may be centrally extended. An explicit and covariant formula for the central charges is constructed. They are shown to be 2-cocycles on the Lie algebra g. The general considerations and formulas are applied to electrodynamics, Yang-Mills theory and Einstein gravity.Comment: 86 pages Latex file; minor correction
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