As intense, ultrashort, kHz-repetition-rate laser systems become commercially available, pulse cumulative effects are critical for laser filament-based applications. In this work, the pulse repetition-rate effect on femtosecond laser filamentation in air was investigated both numerically and experimentally. The pulse repetition-rate effect has negligible influence at the leading edge of the filament. Clear intensity enhancement from a high-repetition pulse is observed at the peak and tailing edge of the laser filament. As the repetition rate of the laser pulses increases from 100 to 1000 Hz, the length of the filament extends and the intensity inside the filament increases. A physical picture based on the pulse repetition-rate dependent ‘low-density hole’ effect on filamentation is proposed to explain the obtained results well.

Most modern-day environmental issues are caused by the complex aggregation and interaction of numerous actions contributing to large-scale problems, from biodiversity loss to climate change. Environmental impact assessments (EIAs) consider how projects contribute to these cumulative environmental problems. This article firstly evaluates the theoretical importance of cumulative effects concepts for EIA. It reveals their potential to spotlight values embedded in decision making and to illuminate, as a lighthouse would, types of harm from broad-ranging, typically unregulated, activities. A large-scale global survey of national EIA laws and multilateral environmental agreements then shows that cumulative effects concepts are legally relevant for most national EIA frameworks. This prevalence suggests that better implementation of cumulative effects provisions may help EIA law to deliver more significant benefits than previously appreciated. Evaluating a sample of EIA provisions shows that cumulative effects concepts can contribute to different stages of an EIA, but that using these concepts across all EIA stages would maximize their potential to achieve the theoretical benefits identified. From theoretical and practical legal perspectives, cumulative effects concepts have significant latent potential – perhaps transformational potential – to address cumulative environmental change through EIA regimes at national and international levels. However, without better implementation, the latent potential of these laws to address cumulative environmental problems is likely to remain unrealized. By shedding light on the extent of national and international legal frameworks that adopt cumulative effects concepts, and their differences, this article highlights the significant learning potential between legal regimes to aid improved implementation.

As human population size and demand for seafood and other marine resources increase, understanding the influence of human activities in the ocean and on land becomes increasingly critical to the management and conservation of marine resources. In order to account for human influence on marine ecosystems while making management decisions, linkages between various anthropogenic pressures and ecosystem components need to be determined. Those linkages cannot be drawn until it is known how different pressures have been changing over time. This paper identifies indicators and develops time series for 22 anthropogenic pressures acting on the USA's portion of the California Current ecosystem. Time series suggest that seven pressures have decreased and two have increased over the short term, while five pressures were above and two pressures were below long-term means. Cumulative indices of anthropogenic pressures suggest a slight decrease in pressures in the 2000s compared to the preceding few decades. Dynamic factor analysis revealed four common trends that sufficiently explained the temporal variation found among all anthropogenic pressures. This reduced set of time series will be a useful tool to determine whether links exist between individual or multiple pressures and various ecosystem components.