Critical behaviour in the nonlinear elastic response of hydrogels

In this paper we study the elastic response of synthetic hydrogels to an applied shear stress. The hydrogels studied here have previously been shown to mimic the behaviour of biopolymer networks when they are sufficiently far above the gel point. We show that near the gel point they exhibit an elastic response that is consistent with the predicted critical behaviour of networks near or below the isostatic point of marginal stability. This point separates rigid and floppy states, distinguished by the presence or absence of finite linear elastic moduli. Recent theoretical work has also focused on the response of such networks to finite or large deformations, both near and below the isostatic point. Despite this interest, experimental evidence for the existence of criticality in such networks has been lacking. Using computer simulations, we identify critical signatures in the mechanical response of sub-isostatic networks as a function of applied shear stress. We also present experimental evidence consistent with these predictions. Furthermore, our results show the existence of two distinct critical regimes, one of which arises from the nonlinear stretch response of semi-flexible polymers.

Why the idea of framework propositions cannot contribute to an understanding of delusions

One of the tasks that recent philosophy of psychiatry has taken upon itself is to extend the range of understanding to some of those aspects of psychopathology that Jaspers deemed beyond its limits. Given the fundamental difficulties of offering a literal interpretation of the contents of primary delusions, a number of alternative strategies have been put forward including regarding them as abnormal versions of framework propositions described by Wittgenstein in On Certainty. But although framework propositions share some of the apparent epistemic features of primary delusions, their role in partially constituting the sense of inquiry rules out their role in helping to understand delusions

Propagule and soil type affects the pathogenicity of Ilyonectria and Dactylonectria spp., the causal agents of black foot disease of grapevines

Black foot disease of grapevines is a significant economic issue for the viticulture industry worldwide. The disease is mainly associated with soil borne pathogen species within the genera Dactylonectria and Ilyonectria. The aim of this study was to determine the pathogenicity of different pathogen propagules, including chlamydospores, conidia and mycelium, to grapevine rootstocks grown in soil. A combination of nine isolates belonging to Dactylonectria and Ilyonectria genera, representative of the fungal species associated with black foot disease in New Zealand were used to inoculate grapevines in a field experiment. In the second experiment, the pathogenicity of the different propagules was assessed in different soil types, clay loam, silt loam and sandy loam soils. In the field experiment, chlamydospores and conidia resulted in higher disease incidence and severity at 0 cm above the grapevine stem base compared with mycelium. At 5 cm above the stem base, chlamydospores caused the greatest disease incidence compared with the other two propagules. Propagule type had no effect on shoot and root dry weights. In the pot experiment, soil type affected disease incidence and severity, with clay loam soil resulting in significantly greater disease incidence and severity than silt loam or sandy loam soils. Disease severity at 0 cm above the stem base was significantly higher with conidial inoculations compared with chlamydospore inoculations irrespective of soil type. Root dry weights were also affected with heavier roots from plants grown in sandy loam compared with silt loam and clay loam soils, however, shoot dry weight was greater in clay loam and sandy loam compared with silt loam soils. The results of the study confirmed that all propagule types were able to infect grapevine rootstocks when planted in inoculated soil and showed that although the pathogens were capable of infecting the rootstocks in all soil types, disease level was higher in the heavier clay loam soil. It is therefore recommended that growers either avoid planting in such soils or apply strategies to improve drainage and soil aeration

Cross-Comparison of Climate Change adaptation Strategies Across Large River Basins in Europe, Africa and Asia

A cross-comparison of climate change adaptation strategies across regions was performed, considering six large river basins as case study areas. Three of the basins, namely the Elbe, Guadiana, and Rhine, are located in Europe, the Nile Equatorial Lakes region and the Orange basin are in Africa, and the Amudarya basin is in Central Asia. The evaluation was based mainly on the opinions of policy makers and water management experts in the river basins. The adaptation strategies were evaluated considering the following issues: expected climate change, expected climate change impacts, drivers for development of adaptation strategy, barriers for adaptation, state of the implementation of a range of water management measures, and status of adaptation strategy implementation. The analysis of responses and cross-comparison were performed with rating the responses where possible. According to the expert opinions, there is an understanding in all six regions that climate change is happening. Different climate change impacts are expected in the basins, whereas decreasing annual water availability, and increasing frequency and intensity of droughts (and to a lesser extent floods) are expected in all of them. According to the responses, the two most important drivers for development of adaptation strategy are: climate-related disasters, and national and international policies. The following most important barriers for adaptation to climate change were identified by responders: spatial and temporal uncertainties in climate projections, lack of adequate financial resources, and lack of horizontal cooperation. The evaluated water resources management measures are on a relatively high level in the Elbe and Rhine basins, followed by the Orange and Guadiana. It is lower in the Amudarya basin, and the lowest in the NEL region, where many measures are only at the planning stage. Regarding the level of adaptation strategy implementation, it can be concluded that the adaptation to climate change has started in all basins, but progresses rather slowl

Disruption of MicroRNA Expression in Human Airway Cells by Diesel Exhaust Particles Is Linked to Tumorigenesis-Associated Pathways

BackgroundParticulate matter (PM) is associated with adverse airway health effects; however, the underlying mechanism in disease initiation is still largely unknown. Recently, microRNAs (miRNAs; small noncoding RNAs) have been suggested to be important in maintaining the lung in a disease-free state through regulation of gene expression. Although many studies have shown aberrant miRNA expression patterns in diseased versus healthy tissue, little is known regarding whether environmental agents can induce such changes.ObjectivesWe used diesel exhaust particles (DEP), the largest source of emitted airborne PM, to investigate pollutant-induced changes in miRNA expression in airway epithelial cells. We hypothesized that DEP exposure can lead to disruption of normal miRNA expression patterns, representing a plausible novel mechanism through which DEP can mediate disease initiation.MethodsHuman bronchial epithelial cells were grown at air–liquid interface until they reached mucociliary differentiation. After treating the cells with 10 μg/cm2 DEP for 24 hr, we analyzed total RNA for miRNA expression using microarray profile analysis and quantitative real-time polymerase chain reaction.ResultsDEP exposure changed the miRNA expression profile in human airway epithelial cells. Specifically, 197 of 313 detectable miRNAs (62.9%) were either up-regulated or down-regulated by 1.5-fold. Molecular network analysis of putative targets of the 12 most altered miRNAs indicated that DEP exposure is associated with inflammatory responses pathways and a strong tumorigenic disease signature.ConclusionsAlteration of miRNA expression profiles by environmental pollutants such as DEP can modify cellular processes by regulation of gene expression, which may lead to disease pathogenesis

'A habitual disposition to the good': on reason, virtue and realism

Amidst the crisis of instrumental reason, a number of contemporary political philosophers including Jürgen Habermas have sought to rescue the project of a reasonable humanism from the twin threats of religious fundamentalism and secular naturalism. In his recent work, Habermas defends a post-metaphysical politics that aims to protect rationality against encroachment while also accommodating religious faith within the public sphere. This paper contends that Habermas’ post-metaphysical project fails to provide a robust alternative either to the double challenge of secular naturalism and religious fundamentalism or to the ruthless instrumentalism that underpins capitalism. By contrast with Habermas and also with the ‘new realism’ of contemporary political philosophers such as Raymond Geuss or Bernard Williams, realism in the tradition of Plato and Aristotle can defend reason against instrumental rationality and blind belief by integrating it with habit, feeling and even faith. Such metaphysical–political realism can help develop a politics of virtue that goes beyond communitarian thinking by emphasising plural modes of association (not merely ‘community’), substantive ties of sympathy and the importance of pursuing goodness and mutual flourishing