Petawatt laser absorption bounded

The interaction of petawatt ($10^{15}\ \mathrm{W}$) lasers with solid matter forms the basis for advanced scientific applications such as table-top particle accelerators, ultrafast imaging systems and laser fusion. Key metrics for these applications relate to absorption, yet conditions in this regime are so nonlinear that it is often impossible to know the fraction of absorbed light $f$, and even the range of $f$ is unknown. Here using a relativistic Rankine-Hugoniot-like analysis, we show for the first time that $f$ exhibits a theoretical maximum and minimum. These bounds constrain nonlinear absorption mechanisms across the petawatt regime, forbidding high absorption values at low laser power and low absorption values at high laser power. For applications needing to circumvent the absorption bounds, these results will accelerate a shift from solid targets, towards structured and multilayer targets, and lead the development of new materials

Meat and morality:The moral foundation of purity, but not harm, predicts attitudes toward cultured meat

Cultured meat (also referred to as cultivated, cell-based, or cell-cultured meat) is a novel food technology that is presented as a method of meat production without reliance on large-scale industrial farming. The pro-cultured meat narrative rests, in part, on a moral foundation: cultured meat is purported to alleviate the environmental and animal welfare harms associated with farmed meat. Despite this narrative, no research has examined which moral values underpin attitudes towards cultured meat. To examine this, we surveyed 1861 participants from the United States and Germany about their moral foundations and their attitudes towards cultured meat. In line with predictions, people who more strongly endorse moral values about purity (i.e., had higher scores on the purity subscale of the moral foundations scale) held more negative attitudes towards cultured meat. However, this relationship was much more consistent among participants from the United States than participants from Germany. Against predictions, attitudes towards cultured meat were not reliably associated with the extent to which people focus on harm as a moral foundation. The latter finding was particularly surprising in light of harm-reduction narratives around cultured meat. These findings demonstrate the need for a more nuanced discussion about, and understanding of, consumer concerns around cultured meat and the values that underpin them

Forecasting infrastructure resilience to climate change

Resilience of the UK transport infrastructure network can be expressed as the imbalance between the physical condition of the network and the transport demands the network experiences. Forecasting changes of resilience in the long term (e.g. the 2050s) requires a structured, multi-disciplinary approach. The Engineering and Physical Sciences Research Council funded Futurenet project developed a model architecture to formalise such an approach and this paper addresses one component: the assessment of the influence of physical processes on asset condition. This requires the development of new, integrated physical-based models that respond to detailed inputs of forecast weather events (e.g. UK Climate Projections 2009). The results are plotted onto the infrastructure network for visualisation. Subsequent combination with user demand will then enable determination of network resilience at a range of spatial scales. The project has highlighted the need for better datasets, more sophisticated physical-based models and further analyses of complex feedbacks and interactions between physical processes and also with user behaviour

Elastomeric polyamide biomaterials with stereochemically tuneable mechanical properties and shape memory

Abstract: Biocompatible polymers are widely used in tissue engineering and biomedical device applications. However, few biomaterials are suitable for use as long-term implants and these examples usually possess limited property scope, can be difficult to process, and are non-responsive to external stimuli. Here, we report a class of easily processable polyamides with stereocontrolled mechanical properties and high-fidelity shape memory behaviour. We synthesise these materials using the efficient nucleophilic thiol-yne reaction between a dipropiolamide and dithiol to yield an α,β − unsaturated carbonyl moiety along the polymer backbone. By rationally exploiting reaction conditions, the alkene stereochemistry is modulated between 35–82% cis content and the stereochemistry dictates the bulk material properties such as tensile strength, modulus, and glass transition. Further access to materials possessing a broader range of thermal and mechanical properties is accomplished by polymerising a variety of commercially available dithiols with the dipropiolamide monomer

Delayed chilling appears to counteract flowering advances of apricot in southern UK

Temperatures are rising across the globe, and the UK is no exception. Spring phenology of perennial fruit crops is to a large extent determined by temperature during effective chilling (endo-dormancy) and heat accumulation (eco-dormancy) periods. We used the apricot flowering records of the UK National Fruit Collections (NFC) to determine the influence of temperature trends over recent decades (1960 to 2014) on apricot (Prunus armeniaca L.) flowering time. Using Partial Least Squares (PLS) regression, we determined the respective periods for calculating chill and heat accumulation. Results suggested intervals between September 27th and February 26th and between December 31st and April 12th as the effective chilling and warming periods, respectively. Flowering time was correlated with temperature during both periods, with warming during chilling corresponding to flowering delays by 4.82 d°C-1, while warming during heat accumulation was associated with bloom advances by 9.85 d°C-1. Heat accumulation started after accumulating 62.7 ± 5.6 Chill Portions, and flowering occurred after a further 3744 ± 1538 Growing Degree Hours (above a base temperature of 4°C, with optimal growth at 26°C). When examining the time series, the increase in temperature during the chilling period did not appear to decrease overall chill accumulation during the chilling period but to delay the onset of chill accumulation and the completion of the the average chill accumulation necessary to start heat accumulation. The resulting delay in heat responsiveness appeared to weaken the phenology-advancing effect of spring warming. These processes may explain why apricot flowering time remained relatively unchanged despite significant temperature increases. A consequence of this may be a reduction of frost risk for early flowering crops such as apricot in the UK