Relaxation dynamics at different time scales in electrostatic complexes: Time-salt superposition

In this Letter we show that in the rheology of electrostatically assembled soft materials, salt concentration plays a similar role as temperature for polymer melts, and as strain rate for soft solids. We rescale linear and nonlinear rheological data of a set of model electrostatic complexes at different salt concentrations to access a range of time scales that is otherwise inaccessible. This provides new insights into the relaxation mechanisms of electrostatic complexes, which we rationalize in terms of a microscopic mechanism underlying salt-enhanced activated processe

Differences in views of experts about their role in particulate matter policy advice: Empirical evidence from an international expert consultation

There is ample scientific evidence of adverse health effects of air pollution at exposure levels that are common among the general population. Some points of uncertainty remain, however. Several theories exist regarding the various roles that experts may play when they offer policy advice on uncertain issues such as particulate matter (PM). Roles may vary according to e.g. the views of the expert on the science-policy interface or the extent to which she/he involves stakeholders. Empirical underpinning of these theories, however, does not exist. We therefore conducted a consultation with experts on the following research question: What are PM experts’ views on their roles when providing policy advice? Q methodology was used to empirically test theoretical notions concerning the existence of differences in views on expert roles. Experts were selected based on a structured nominee process. In total, 31 international PM experts participated. Responses were examined via Principal Component Analysis, and for the open-ended questions, we used Atlas.ti software. Four different expert roles were identified among the participating experts. Main differences were found with respect to views on the need for precautionary measures and on the experts positioning within the science-policy interface. There was consensus on certain issues such as the need for transparency, general disagreement with current policies and general agreement on key scientific issues. This empirical study shows that while most PM experts consider their views on the risks of PM to be in line with those of their colleagues, four distinct expert roles were observed. This provides support for thus far largely theoretical debates on the existence of different roles of experts when they provide policy advice

Universal Algebraic Relaxation of Velocity and Phase in Pulled Fronts generating Periodic or Chaotic States

We investigate the asymptotic relaxation of so-called pulled fronts propagating into an unstable state. The ``leading edge representation'' of the equation of motion reveals the universal nature of their propagation mechanism and allows us to generalize the universal algebraic velocity relaxation of uniformly translating fronts to fronts, that generate periodic or even chaotic states. Such fronts in addition exhibit a universal algebraic phase relaxation. We numerically verify our analytical predictions for the Swift-Hohenberg and the Complex Ginzburg Landau equation.Comment: 4 pages Revtex, 2 figures, submitted to Phys. Rev. Let

Slaughter of poultry during the epidemic of avian influenza in the Netherlands in 2003

During an outbreak of avian influenza in the Netherlands in spring 2003, the disease was controlled by destroying all the poultry on the infected farms and on all the farms within a radius of 3 km. In total, 30 million birds were killed on 1242 farms and in more than 8000 hobby flocks, by using mobile containers filled with carbon dioxide, mobile electrocution lines and by gassing whole poultry houses with carbon monoxide or carbon dioxide. Observations of these methods were used to compare their effectiveness and capacity, and their effects on the welfare of the birds. Gassing whole poultry houses had a much greater capacity than mobile equipment, and catching live birds to bring them to a mobile killing device caused extra stress and could cause pain due to injuries inflicted when catching and handling them. Gassing whole poultry houses with carbon monoxide requires strict safety regulations and, therefore, gassing with carbon dioxide was considered preferable. However, this method is not suited to all types of housing, and in these circumstances mobile killing devices were a useful alternativ

Expert Views on Their Role as Policy Advisor: Pilot Study for the Cases of Electromagnetic Fields, Particulate Matter, and Antimicrobial Resistance

This perspective presents empirical data to demonstrate the existence of different expert views on scientific policy advice on complex environmental health issues. These views are partly research-field specific. According to scientific literature, experts differ in the way they provide policy advice on complex issues such as electromagnetic fields (EMF), particulate matter (PM), and antimicrobial resistance (AMR). Where some experts feel their primary task is to carry out fundamental research, others actively engage in the policy dialogue. Although the literature provides ideas about expert roles, there exists little empirical underpinning. Our aim is to gather empirical evidence about expert roles. The results of an international study indicated that experts on EMF, PM, and AMR differ in the way they view their role in the policy dialogue. For example, experts differed in their views on the need for precaution and their motivation to initiate stakeholder cooperation. Besides, most experts thought that their views on the risks of EMF/PM/AMR did not differ from those of colleagues. Great dissensus was found in views on the best ways of managing risks and uncertainties. In conclusion, the theoretical ideal-typical roles from the literature can be identified to a certain extent

Roles of scientists as policy advisers on complex issues: A literature review

Background and Aims: Policymakers frequently encounter complex issues, and the role of scientists as policy advisers on these issues is not always clearly defined. We present an overview of the interdisciplinary literature on the roles of scientific experts when advising policymakers on complex issues, and in particular on the factors that influence these roles. / Methods: A structured literature search was combined with literature found in reference lists of peer reviewed papers (the snowball method). In total, 267 publications were analyzed using scientometrics analyses (discipline clustering analysis and co-citation analysis) followed by a qualitative analysis and interpretation. / Results: The scientometrics analysis shows an amalgam of disciplines that publish on our research topic. Five clusters of authors were identified based on similarities in the references used: post-normal science, science and technology studies, science policy studies, politics of expertise and risk governance. The content of the clusters demonstrates that authors in different clusters agree that the role of experts is influenced by the type of problem (simple or complex) and by other parties (the public and stakeholders). However, opinions vary on the extent to which roles can vary and the necessity to explicate different viewpoints. / Discussion and conclusions: Publications on scientific experts who provide policy advice affirm that such experts should and do hold different roles, depending on the type of problem and factors such as values held by the expert and the type of knowledge. We conclude that research on expert roles has remained mostly theoretical. Existing theories about science systems can be used to study real policy advice processes. Most theories are well elaborated, but empirical proof for the described changes, roles and processes is limited

Population-specific use of the same tool-assisted alarm call between two wild orangutan populations (Pongopygmaeus wurmbii) indicates functional arbitrariness

This study was financially supported by Fundação para a Ciência e Tecnologia (SFRH/BD/44437/2008), Wenner-Gren Foundation for Anthropological Research, Dr. J.L. Dobberke voor Vergelijkende Psychologie, Lucie Burgers Foundation for Comparative Behaviour Research, Schure-Beijerinck-Popping Fonds, Ruggles-Gates Fund for Anthropological Scholarship of the Royal Anthropological Institute of Great Britain and Ireland, and Fundação Calouste Gulbenkian. KN and ET were financially supported by Pongo Foundation. Orangutan fieldwork at Cabang Panti was supported by grants to CDK from the 16 National Science Foundation (0936199), the National Geographic Society, the Leakey Foundation and the US Fish and Wildlife Service.Arbitrariness is an elementary feature of human language, yet seldom an object of comparative inquiry. While arbitrary signals for the same function are relatively frequent between animal populations across taxa, the same signal with arbitrary functions is rare and it remains unknown whether, in parallel with human speech, it may involve call production in animals. To investigate this question, we examined a particular orangutan alarm call - the kiss-squeak - and two variants - hand and leaf kiss-squeaks. In Tuanan (Central Kalimantan, Indonesia), the acoustic frequency of unaided kiss-squeaks is negatively related to body size. The modified variants are correlated with perceived threat and are hypothesized to increase the perceived body size of the sender, as the use of a hand or leaves lowers the kiss-squeak's acoustic frequency. We examined the use of these variants in the same context in another orangutan population of the same sub-species and with partially similar habitat at Cabang Panti (West Kalimantan, Indonesia). Identical analyses of data from this site provided similar results for unaided kiss-squeaks but dissimilar results for hand and leaf kiss-squeaks. Unaided kiss-squeaks at Cabang Panti were emitted as commonly and showed the same relationship to body size as in Tuanan. However, at Cabang Panti, hand kiss-squeaks were extremely rare, while leaf-use neither conveyed larger body size nor was related to perceived threat. These findings indicate functional discontinuity between the two sites and therefore imply functional arbitrariness of leaf kiss-squeaks. These results show for the first time the existence of animal signals involving call production with arbitrary function. Our findings are consistent with previous studies arguing that these orangutan call variants are socially learned and reconcile the role of gestures and calls within evolutionary theories based on common ancestry for speech and music.Publisher PDFPeer reviewe