Optimal abatement of sulphur emissions in Europe

This study presents a mathematical model for determining cost-effective emissions' control strategies in Europe, by minimizing sulphur abatement costs subject to different pollution control targets. The purpose is to compare the efficiency of a uniform percentage emissions reduction with a scenario that takes variation in environmental conditions into account. Underlying the proposed model is the belief that a full cost-benefit analysis of acid rain abatement is infeasible. The model focuses on the costs of abatement and provides an estimation of the gains (or losses) that countries could achieve if they co-operate in their policies rather than act independently.     

Processes of auditability in sustainability assurance – the case of materiality construction

This study examines how financial audit-styled concepts such as materiality are transferred to non-financial audit arenas. Drawing on a case study of assurors working within a Big 4 professional services firm, we uncover a number of interrelated features of the materiality determination and assessment process within sustainability assurance (assurance on sustainability reports). We illustrate how assuror flexibility, underpinned by assuror intuition, is central to uncovering assurance technologies deemed capable of addressing the materiality of ambiguous sustainability data. Assurors with no financial audit background retrospectively rationalise their intuition using the assumed authority of structured financial audit methodologies. This facilitates the tentative translation of financial audit knowledge to the sustainability assurance domain. Collaborative, holistic decision-making processes inform the assurors’ continual construction of materiality and are characterised by alliances of (accountant and non-accountant) ‘expert’ assurors merging formal and tacit knowledge. These alliances seek social cohesion within sustainability assurance teams in order to establish a social consensus among assurors around the materiality determination and assessment process. Our analysis develops and extends Power’s theorisation of how new areas are made auditable and advances our understanding of the more practical aspects of non-financial assurance services offered by Big 4 professional services firms.     

化肥减施程度与环境风险时空差异研究——基于动态环境安全阈值测度视角

目的 文章测度不同地区化肥施用的动态环境安全阈值,明确各地区化肥施用的环境容量边界和减施空间,科学评估不同区域化肥施用的环境风险。方法 鉴于不同类型作物对各单质肥的吸收量有着较大差异,选择总种植面积占比最大的5类大宗作物为研究对象,通过对1980—2021年31个省市区5类大宗作物的实际产量进行模拟回归分析,得出其趋势产量;根据各大类作物对养分的需求量以及种植面积的权重,分别对各地区氮、磷、钾及总施肥的环境安全阈值进行测算;以此作为分析基础,计算出各地区化肥减施空间和化肥环境风险指数。结果 （1）化肥施用安全阈值并非一个静态标准值,同一时期不同类型作物安全阈值差别很大,同类型作物不同时期安全阈值呈现动态变化,同一时期同类作物不同区域安全阈值存在差异。（2）对比各地区安全阈值与化肥实际施用强度,发现氮、磷、钾单质肥及总化肥用量空间上表现出施用过量与施用不足并存的现象,各地区化肥环境风险指数随时间推移呈现先上升后下降的变化趋势,且各地区出现拐点的时间不同。结论 需要通过建立和完善化肥施用数据库、确立差异化化肥减施方案、保持稳定合理种植结构、推广普及科学施肥技术、实施土壤健康卡评估办法等措施推进农业生产减施降排。     

A variable threshold band approach to measuring market linkages

Uncertain and changing economic conditions can have substantial effects on price relationships in spatially separated, linked markets. Although numerous studies have analysed price relationships to characterize market linkage structures, most assume that the relationships and associated linkages are time invariant. This study extends the literature by modelling and estimating time-dependent market linkages that are conditional on changes in exogenous factors. The methodology is used to investigate price relationships in North Carolina (NC) corn and soya bean markets. Empirical results indicate that generalized market-linkage models provide a better representation of price relationships over time, improving the understanding of price discovery dynamics and marketing strategies.     

Analytic value function for a pairs trading strategy with a Lévy-driven Ornstein–Uhlenbeck process

This paper studies the performance of pairs trading strategy under a specific spread model. Based on the empirical evidence of mean reversion and jumps in the spread between pairs of stocks, we assume that the spread follows a Lévy-driven Ornstein–Uhlenbeck process with two-sided jumps. To evaluate the performance of a pairs trading strategy, we propose the expected return per unit time as the value function of the strategy. Significantly different from the current related works, we incorporate an excess jump component into the calculation of return and time cost. Further, we obtain the analytic expression of strategy value function, where we solve out the probabilities of crossing thresholds via the Laplace transform of first passage time of the Lévy-driven Ornstein–Uhlenbeck process in one-sided and two-sided exit problems. Through numerical illustrations, we calculate the value function and optimal thresholds for a spread model with symmetric jumps, reveal the non-negligible contribution of incorporating the excess jumps into the value function, and analyze the impact of model parameters on the strategy performance.     

Green Agriculture: foundations for biodiverse,resilient and productive agricultural systems

There are many visions on how to achieve a sustainable agriculture that provides enough food and ecosystem services for present and future generations in an era of climate change, increasing costs of energy, social unrest, financial instability and increasing environmental degradation. New agricultural systems that are able to confront the challenges of a rapidly changing world require a minimum of ten attributes that constitute the defining elements of a Green Agriculture. A major challenge is to identify a set of thresholds that any agricultural production strategy must meet, beyond which unsustainable trends caused by the farming technologies would lead to tipping-point phenomena. Only those styles of agriculture that meet the established threshold criteria while advancing rural communities towards food, energy and technological sovereignty would be considered viable forms of Green Agriculture. Considering the diversity of ecological, socio-economic, historical and political contexts in which agricultural systems have developed and are evolving in, it is only wise to define a set of flexible and locally adaptable principles and boundaries of sustainability and resiliency for the agroecosystems of the immediate future.     

What Determines the Finance-growth Nexus? Empirical Evidence for Threshold Models

This paper elaborates the notion of ``balanced' financial development that is contingent on a country's general level of development. We develop an empirical framework to address this point, referring to threshold regressions and a bootstrap test for structural shift in a growth equation. We find that countries gain less from financial activity, if the latter fails to keep up with or exceeds what would follow from a balanced expansion path. These analyses contribute to the finance and growth literature in providing empirical support for the ``balanced' financial development hypothesis.