Living with Ghosts and their Radiative Corrections

The role of higher derivative operators in 4D effective field theories is discussed in both non-supersymmetric and supersymmetric contexts. The approach, formulated in the Minkowski space-time, shows that theories with higher derivative operators do not always have an improved UV behaviour, due to subtleties related to the analytical continuation from the Minkowski to the Euclidean metric. This continuation is further affected at the dynamical level due to a field-dependence of the poles of the Green functions of the particle-like states, for curvatures of the potential of order unity in ghost mass units. The one-loop scalar potential in lambda*phi^4 theory with a single higher derivative term is shown to have infinitely many counterterms, while for a very large mass of the ghost the usual 4D renormalisation is recovered. In the supersymmetric context of the O'Raifeartaigh model of spontaneous supersymmetry breaking with a higher derivative (supersymmetric) operator, it is found that quadratic divergences are present in the one-loop self-energy of the scalar field. They arise with a coefficient proportional to the amount of supersymmetry breaking and suppressed by the scale of the higher derivative operator. This is also true in the Wess-Zumino model with higher derivatives and explicit soft breaking of supersymmetry. In both models, the UV logarithmic behaviour is restored in the decoupling limit of the ghost.The role of higher derivative operators in 4D effective field theories is discussed in both non-supersymmetric and supersymmetric contexts. The approach, formulated in the Minkowski space-time, shows that theories with higher derivative operators do not always have an improved UV behaviour, due to subtleties related to the analytical continuation from the Minkowski to the Euclidean metric. This continuation is further affected at the dynamical level due to a field-dependence of the poles of the Green functions of the particle-like states, for curvatures of the potential of order unity in ghost mass units. The one-loop scalar potential in lambda*phi^4 theory with a single higher derivative term is shown to have infinitely many counterterms, while for a very large mass of the ghost the usual 4D renormalisation is recovered. In the supersymmetric context of the O'Raifeartaigh model of spontaneous supersymmetry breaking with a higher derivative (supersymmetric) operator, it is found that quadratic divergences are present in the one-loop self-energy of the scalar field. They arise with a coefficient proportional to the amount of supersymmetry breaking and suppressed by the scale of the higher derivative operator. This is also true in the Wess-Zumino model with higher derivatives and explicit soft breaking of supersymmetry. In both models, the UV logarithmic behaviour is restored in the decoupling limit of the ghost.The role of higher derivative operators in 4D effective field theories is discussed in both non-supersymmetric and supersymmetric contexts. The approach, formulated in the Minkowski space–time, shows that theories with higher derivative operators do not always have an improved UV behaviour, due to subtleties related to the analytical continuation from the Minkowski to the Euclidean metric. This continuation is further affected at the dynamical level due to a field-dependence of the poles of the Green functions of the particle-like states, for curvatures of the potential of order unity in ghost mass units. The one-loop scalar potential in λ ϕ 4 theory with a single higher derivative term is shown to have infinitely many counterterms, while for a very large mass of the ghost the usual 4D renormalisation is recovered. In the supersymmetric context of the O'Raifeartaigh model of spontaneous supersymmetry breaking with a higher derivative (supersymmetric) operator, it is found that quadratic divergences are present in the one-loop self-energy of the scalar field. They arise with a coefficient proportional to the amount of supersymmetry breaking and suppressed by the scale of the higher derivative operator. This is also true in the Wess–Zumino model with higher derivatives and explicit soft breaking of supersymmetry. In both models, the UV logarithmic behaviour is restored in the decoupling limit of the ghost

Addressing grand ecological challenges in aquatic ecosystems: how can mesocosms be used to advance solutions?

Rapid and drastic anthropogenic impacts are affecting global biogeochemical processes and driving biodiversity loss across Earth's ecosystems. In aquatic ecosystems, species distributions are shifting, abundances of many species have declined dramatically, and many are threatened with extinction. In addition to loss of diversity, the ecosystem functions, processes and services on which humans depend are also being heavily impacted. Addressing these challenges not only requires direct action to mitigate environmental impacts but also innovative approaches to identify, quantify and treat their effects in the environment. Mesocosms are valuable tools for achieving these goals as they provide controlled environments for evaluating effects of stressors and testing novel mitigation measures at multiple levels of biological organisation. Here, we summarise discussions from a survey of marine and freshwater researchers who use mesocosm systems to synthesise their opportunities and limitations for advancing solutions to grand ecological challenges in aquatic ecosystems. While most research utilising mesocosm systems in aquatic ecology has focused on quantifying the effects of environmental threats, there is a largely unexplored potential for using them to test solutions. To overcome spatio-temporal constraints, there are opportunities to scale up the size and time-scales of mesocosm studies, or alternatively, test the outcomes of habitat-scale restoration at a smaller scale. Enhancing connectivity in future studies can help to overcome the limitation of isolation and test an important aspect of ecological recovery. Conducting ‘metacosm' studies: coordinated, distributed mesocosm experiments spanning wide climatic and environmental gradients and utilising more regression-based experimental designs can help to tackle the challenge of context dependent results. Finally, collaboration of theoretical, experimental and applied ecologists and biogeochemists with environmental engineers and technological developers will be necessary to develop and test the tools required to advance solutions to the impacts of human activities on Earth's vulnerable aquatic ecosystems.Environmental Biolog

Impact of global warming on beef cattle production cost in Brazil

Global warming is affecting agribusiness in its economic aspects. Therefore, the prediction of the evolution of Brazilian beef cattle production cost was made using the IPCC forecast scenario for global warming. The methodology consisted of two steps: (i) the development of a fuzzy model that estimated the grazing land capacity (RP) decrease risk as a function of the changes in the average total rain index, air temperature and increase in extension of the dry season; and (ii) the design of an algorithm for predicting the decrease in production as function of the RPfuzzy model, that results in the impact in beef cattle productivity, and consequent increase in production costs. Historical environmental data from important producing counties in the Cerrado were organized and a set of fuzzy Gaussian functions were developed, and three possible settings (optimistic, medium and pessimistic) were considered. The decrease in beef cattle productivity was estimated using the losses in production due to the increase in air temperature and vulnerability of pasture capacity. The boundary settings for the total increase of production cost scenario used the number of animals per area of grazing land, the adoption of grain supplement and its future scenario; and the result output function pointed to a threshold within a variation from an increase in production cost of 80% (optimistic) to 160% (pessimistic). Under the optimistic scenario the total cost of Brazilian beef cattle production in the Cerrado became near to US$2.88 kg-1, while in the pessimistic scenario this cost reached US$ 4.16 kg-1, challenging the international competitiveness of this economic segment.O aquecimento global afeta o agronegócio em seus aspectos econômicos. Foi feita previsão daevolução do custo de produção de carne bovina brasileira usando a predição de aquecimento global do IPCC. A metodologia consistiu de duas etapas: (i) o desenvolvimento de modelo fuzzy que estimou o risco de decréscimo da capacidade de pastagens (RP) em função das mudanças no índice pluviométrico total, na temperatura do ar e na extensão da estação de seca; e (ii) o desenvolvimento de um algoritmo para predição do decréscimo da produção em função de um modelo fuzzy de RP que resulte no impacto na produtividade bovina de corte e conseqüente aumento no custo de produção. Foram organizados os dados históricos de fatores ambientais dos municípios importante produção no Cerrado e um conjunto de funções Gaussianas fuzzy foi desenvolvido e três estimativas possíveis (otimista, média e negativa) foram consideradas. O decréscimo na produtividade do gado foi estimado usando as perdas de produção devido ao acréscimo da temperatura bem como da vulnerabilidade da capacidade de pastagem. O estabelecimento dos limites para o cenário do acréscimo do custo de produção usou o número de unidade animal por área de pastagem, a adoção de suplemento de grãos e o cenário de produção futura; e o resultado da função de saída apontou para uma variação do acréscimo do custo de produção de 80% (otimista) até 160% (pessimista). Sob o cenário otimista, o custo total da produção brasileira de carne bovina no Cerrado chega a US$2,88 kg-1, enquanto no cenário pessimista este custo pode atingir US$ 4,16 kg-1, o que pode comprometer a competitividade internacional do setor

The microtubule- and PP1-binding activities of Drosophila melanogaster Spc105 control the kinetics of SAC satisfaction

KNL1 is a large intrinsically disordered kinetochore (KT) protein that recruits spindle assembly checkpoint (SAC) components to mediate SAC signaling. The N-terminal region (NTR) of KNL1 possesses two activities that have been implicated in SAC silencing: microtubule (MT) binding and protein phosphatase 1 (PP1) recruitment. The NTR of Drosophila melanogaster KNL1 (Spc105) has never been shown to bind MTs or to recruit PP1. Furthermore, the phosphoregulatory mechanisms known to control SAC protein binding to KNL1 orthologues is absent in D. melanogaster. Here, these apparent discrepancies are resolved using in vitro and cell-based assays. A phosphoregulatory circuit that utilizes Aurora B kinase promotes SAC protein binding to the central disordered region of Spc105 while the NTR binds directly to MTs in vitro and recruits PP1-87B to KTs in vivo. Live-cell assays employing an optogenetic oligomerization tag and deletion/chimera mutants are used to define the interplay of MT and PP1 binding by Spc105 and the relative contributions of both activities to the kinetics of SAC satisfaction.</p