Mirror formation control in the vicinity of an asteroid

Two strategies are presented for the positioning and control of a spacecraft formation designed to focus sunlight onto a point on the surface of asteroid, thereby sublimating the material and ejecting debris creating thrust. In the first approach, the formation is located at artficial equilibrium points around the asteroid and controlled using the force from the solar radiation pressure. The second approach determines the optimal periodic formation orbits, subject to the gravitational perturbations from the asteroid, the solar radiation pressure and the control acceleration derived from a control law

Enzyme-catalysed polymer cross-linking:Biocatalytic tools for chemical biology, materials science and beyond

Intermolecular cross-linking is one of the most important techniques that can be used to fundamentally alter the material properties of a polymer. The introduction of covalent bonds between individual polymer chains creates 3D macromolecular assemblies with enhanced mechanical properties and greater chemical or thermal tolerances. In contrast to many chemical cross-linking reactions, which are the basis of thermoset plastics, enzyme catalysed processes offer a complimentary paradigm for the assembly of cross-linked polymer networks through their predictability and high levels of control. Additionally, enzyme catalysed reactions offer an inherently ‘greener’ and more biocompatible approach to covalent bond formation, which could include the use of aqueous solvents, ambient temperatures, and heavy metal-free reagents. Here, we review recent progress in the development of biocatalytic methods for polymer cross-linking, with a specific focus on the most promising candidate enzyme classes and their underlying catalytic mechanisms. We also provide exemplars of the use of enzyme catalysed cross-linking reactions in industrially relevant applications, noting the limitations of these approaches and outlining strategies to mitigate reported deficiencies

The Suaineadh Project : a stepping stone towards the deployment of large flexible structures in space

The Suaineadh project aims at testing the controlled deployment and stabilization of space web. The deployment system is based on a simple yet ingenious control of the centrifugal force that will pull each of the four daughters sections apart. The four daughters are attached onto the four corners of a square web, and will be released from their initial stowed configuration attached to a central hub. Enclosed in the central hub is a specifically designed spinning reaction wheel that controls the rotational speed with a closed loop control fed by measurements from an onboard inertial measurement sensor. Five other such sensors located within the web and central hub provide information on the surface curvature of the web, and progression of the deployment. Suaineadh is currently at an advanced stage of development: all the components are manufactured with the subsystems integrated and are presently awaiting full integration and testing. This paper will present the current status of the Suaineadh project and the results of the most recent set of tests. In particular, the paper will cover the overall mechanical design of the system, the electrical and sensor assemblies, the communication and power systems and the spinning wheel with its control system

Hazardous near Earth asteroid mitigation campaign planning based on uncertain information on fundamental asteroid characteristics

Given a limited warning time, an asteroid impact mitigation campaign would hinge on uncertainty-based information consisting of remote observational data of the identified Earth-threatening object, general knowledge of near-Earth asteroids (NEAs), and engineering judgment. Due to these ambiguities, the campaign credibility could be profoundly compromised. It is therefore imperative to comprehensively evaluate the inherent uncertainty in deflection and plan the campaign accordingly to ensure successful mitigation. This research demonstrates dual-deflection mitigation campaigns consisting of primary (instantaneous/quasi-instantaneous) and secondary (slow-push) deflection missions, where both deflection efficiency and campaign credibility are taken into account. The results of the dual-deflection campaign analysis show that there are trade-offs between the competing aspects: the launch cost, mission duration, deflection distance, and the confidence in successful deflection. The design approach is found to be useful for multi-deflection campaign planning, allowing us to select the best possible combination of missions from a catalogue of campaign options, without compromising the campaign credibility

Baby Pigs Have a Sweet Tooth!

Early gains are the cheapest. And you can get faster early gains by feeding a good pig starter. In this article, the others tell how pig starters can be made more palatable and also what should go into a good pig starter

Diet quality in late midlife is associated with faster walking speed in later life in women, but not men

Healthy diet has been linked to better age-related physical functioning, but evidence on the relationship of overall diet quality in late midlife and clinically relevant measures of physical functioning in later life is limited. Research on potential sex differences in this relationship is scarce. The aim was to investigate the prospective association between overall diet quality, as assessed by the Healthy Eating Index-2015 at age 60-64y and measures of walking speed seven years later, among men and women from the Insight46, a neuroscience sub-study of the Medical Research Council National Survey of Health and Development. Diet was assessed at age 60-64y using five-day food diaries, from which total HEI-2015 was calculated. At age 69-71y, walking speed was estimated during four 10-meter walks at self-selected pace, using inertial measurement units. Multivariable linear regression models with sex as modifier, controlling for age, follow-up, lifestyle, health, social variables and physical performance were used. The final sample was 164 women and 167 men (n=331). Women had higher HEI-2015 scores and slower walking speed than men. A 10 point increase in HEI-2015 was associated with faster walking speed seven years later among women (B: 0.024, 95% CI: 0.006, 0.043), but not men. The association remained significant in the multivariable model (B: 0.021, 95% CI: 0.003, 0.040). In women in late midlife higher diet quality is associated with faster walking speed. A healthy diet in late midlife is likely to contribute towards better age-related physical capability and sex differences are likely to affect this relationship

Universal architecture of bacterial chemoreceptor arrays

Chemoreceptors are key components of the high-performance signal transduction system that controls bacterial chemotaxis. Chemoreceptors are typically localized in a cluster at the cell pole, where interactions among the receptors in the cluster are thought to contribute to the high sensitivity, wide dynamic range, and precise adaptation of the signaling system. Previous structural and genomic studies have produced conflicting models, however, for the arrangement of the chemoreceptors in the clusters. Using whole-cell electron cryo-tomography, here we show that chemoreceptors of different classes and in many different species representing several major bacterial phyla are all arranged into a highly conserved, 12-nm hexagonal array consistent with the proposed “trimer of dimers” organization. The various observed lengths of the receptors confirm current models for the methylation, flexible bundle, signaling, and linker sub-domains in vivo. Our results suggest that the basic mechanism and function of receptor clustering is universal among bacterial species and was thus conserved during evolution

Somaclonal variation in the gliadin patterns of grains of regenerated wheat plants

The banding patterns of the gliadin storage proteins of the grains of 590 regenerated plants from six wheat cultivars were examined by polyacrylamide gel electrophoresis using lactate buffer. Variation additional to that present in control material was observed at a low frequency (∼1%). Two variant lines showed extensive changes in banding patterns which were accompanied by morphological variation of the plants. More limited variation in the form of an extra ω–gliadin band was observed in a third line. Differences in the seed gliadins were not found in four lines which had shown stable phenotypic changes in height in field trials