Taxonomic, anatomical, and spatio-temporal variations in the stable carbon and nitrogen isotopic compositions of plants from an African savanna

Stable carbon (δ¹³C) and nitrogen (δ¹⁵N) isotope ratios are commonly used to reconstruct palaeodiets and palaeoenvironments. The method is based on our knowledge of isotopic patterns in plants, which are subject to taxonomic and environmental variability. While previous researchers have addressed isotopic variability amongst plants, no studies have looked extensively at a broad suite of taxa over multiple temporal scales from within the savanna biome so as to provide baseline data for palaeodietary and palaeoenvironmental studies. Here we document variations in the isotopic compositions of plants collected over two years from the Kruger National Park, South Africa, with respect to species and anatomical differences, and the influences of geological substrate and spatio-temporal shifts in climate. Results show that environmentally-induced carbon isotopic variations in plants within this region are generally smaller than 2‰, which is lower than what has been previously reported for plants compared across multiple habitat-types. These data suggest that δ¹³C differences of 2‰ or more (or 1‰ if the diet is predominantly C₄) between animals from a given area reliably indicate real dietary differences. Plant δ¹⁵N values vary greatly between different microhabitats (by up to 4‰), responding to a range of environmental influences that may, in turn, significantly influence variation in animal δ¹⁵N values.     

Perceived Risk and Citizen Preferences for Governmental Management of Routine Hazards

Risk perceptions are important to the policy process because they inform individuals’ preferences for government management of hazards that affect personal safety, public health, or ecological conditions. Studies of risk in the policy process have often focused on explicating the determinants of risk perceptions for highly salient, high consequence hazards (e.g., nuclear energy). We argue that it is useful to also study more routinely experienced hazards; doing so shows the relevance of risk perceptions in individuals’ daily lives. Our investigation focuses on the impact perceived risk has on citizens’ preferences over hazard management policies (as distinct from identifying risk perception determinants per se). We use a recursive structural equation model to analyze public opinion data measuring attitudes in three distinct issue domains: air pollution, crime, and hazardous waste storage and disposal. We find that citizens utilize perceived risk rationally: greater perceived risk generally produces support for more proactive government to manage potential hazards. This perceived risk–policy response relationship generally holds even though the policy options respondents were asked to consider entailed nontrivial costs to the public. The exception seems to be when individuals know less about the substantive issue domain.     

Digital Dialogue? Australian Politicians' use of the Social Network Tool Twitter

The recent emergence of online social media has had a significant effect on the contemporary political landscape, yet our understanding of this remains less than complete. This article adds to current understanding of the online engagement between politicians and the public by presenting the first quantitative analysis of the utilisation of the social network tool Twitter by Australian politicians. The analysis suggests that politicians are attempting to use Twitter for political engagement, though some are more successful in this than others. Politicians are noisier than Australians in general on Twitter, though this is due more to broadcasting than conversing. Those who use Twitter to converse appear to gain more political benefit from the platform than others. Though politicians cluster by party, a relatively ‘small world’ network is evident in the Australian political discussion on Twitter.     

The Netherlands in the constellation of the eighteenth-century Western revolutions

In the constellation of the eighteenth-century revolutions, the French events have always occupied a dominant position. Consequently the other European upheavals have been considered as being provoked or strongly influenced by France. Yet, the Dutch revolutions in the 1780s and 1790s provide some important nuances to this interpretation. Before the French took over the Bastille, there was already a Dutch revolution with devoted Patriots, speaking about rights of man and constitutions. The Patriots had to flee abroad in 1787. In 1795, thanks to the French Army, they were able to return to their drawing boards, eager to think anew their government and society. This paper investigates how they did it and whether the American and French precedents were so influential after all in the construction of the Batavian Republic.