Minimal activation with maximal reach: Reachability clouds of bio-inspired slender manipulators

In the field of soft robotics, flexibility, adaptability, and functionality define a new era of robotic systems that can safely deform, reach, and grasp. To optimize the design of soft robotic systems, it is critical to understand their configuration space and full range of motion across a wide variety of design parameters. Here we integrate extreme mechanics and soft robotics to provide quantitative insights into the design of bio-inspired soft slender manipulators using the concept of reachability clouds. For a minimal three-actuator design inspired by the elephant trunk, we establish an efficient and robust reduced-order method to generate reachability clouds of almost half a million points each to visualize the accessible workspace of a wide variety of manipulator designs. We generate an atlas of 256 reachability clouds by systematically varying the key design parameters including the fiber count, revolution, tapering angle, and activation magnitude. Our results demonstrate that reachability clouds not only offer an immediately clear perspective into the inverse problem of control, but also introduce powerful metrics to characterize reachable volumes, unreachable regions, and actuator redundancy to quantify the performance of soft slender robots. Our study provides new insights into the design of soft robotic systems with minimal activation and maximal reach with potential applications in medical robotics, flexible manufacturing, and the autonomous exploration of space.Comment: 13 pages, 4 figure

Risk and protective factors for meningococcal disease in adolescents: matched cohort study

Objective: To examine biological and social risk factors for meningococcal disease in adolescents. Design: Prospective, population based, matched cohort study with controls matched for age and sex in 1:1 matching. Controls were sought from the general practitioner. Setting: Six contiguous regions of England, which represent some 65% of the country’s population. Participants: 15-19 year olds with meningococcal disease recruited at hospital admission in six regions (representing 65% of the population of England) from January 1999 to June 2000, and their matched controls. Methods: Blood samples and pernasal and throat swabs were taken from case patients at admission to hospital and from cases and matched controls at interview. Data on potential risk factors were gathered by confidential interview. Data were analysed by using univariate and multivariate conditional logistic regression. Results: 144 case control pairs were recruited (74 male (51%); median age 17.6). 114 cases (79%) were confirmed microbiologically. Significant independent risk factors for meningococcal disease were history of preceding illness (matched odds ratio 2.9, 95% confidence interval 1.4 to 5.9), intimate kissing with multiple partners (3.7, 1.7 to 8.1), being a university student (3.4, 1.2 to 10) and preterm birth (3.7, 1.0 to 13.5). Religious observance (0.09, 0.02 to 0.6) and meningococcal vaccination (0.12, 0.04 to 0.4) were associated with protection. Conclusions: Activities and events increasing risk for meningococcal disease in adolescence are different from in childhood. Students are at higher risk. Altering personal behaviours could moderate the risk. However, the development of further effective meningococcal vaccines remains a key public health priority

Phase diagram of silicon from atomistic simulations

In this letter we present a calculation of the temperature-pressure phase diagram of Si in a range of pressures covering from -5 to 20 GPa and temperatures up to the melting point. The phase boundaries and triple points between the diamond, liquid, $\beta$-Sn and ${Si}_{34}$ clathrate phases are reported. We have employed efficient simulation techniques to calculate free energies and to numerically integrate the Clausius-Clapeyron equation, combined with a tight binding model capable of an accuracy comparable to that of first-principles methods. The resulting phase diagram agrees well with the available experimental data.Comment: 5 pages, 1 figure, accepted in PR

Minimal design of the elephant trunk as an active filament

One of the key problems in active materials is the control of shape through actuation. A fascinating example of such control is the elephant trunk, a long, muscular, and extremely dexterous organ with multiple vital functions. The elephant trunk is an object of fascination for biologists, physicists, and children alike. Its versatility relies on the intricate interplay of multiple unique physical mechanisms and biological design principles. Here we explore these principles using the theory of active filaments and build, theoretically, computationally, and experimentally, a minimal model that explains and accomplishes some of the spectacular features of the elephant trunk.Comment: 13 pages, 7 figure

Book Review Roundtable: Kathryn E. Stoner’s Russia Resurrected: Its Power and Purpose in a New Global Order and James Reilly’s Orchestration: China’s Economic Statecraft Across Asia and Europe

This double book review roundtable examines the drivers and international influence of Russia and China. It features Kathryn Stoner’s Russia Resurrected: Its Power and Purpose in a New Global Order and James Reilly’s Orchestration: China’s Economic Statecraft Across Asia and Europe

Phase Equilibria in Triacylglycerols – Ethanol – Oleic Acid – Athyl Oleate Quasi-Quaternary System

In order to use waste vegetable oils to produce biodiesel a possibility of reagents (sunflower oil and ethanol) mixture homogenization under the simultaneous effect of two cosolvents (oleic acid and ethyl oleate) was investigated. The possibility of action of oleic acid and ethyl oleate as cosolvents was analyzed with GSP model. For qualitative assessment of the intermolecular interaction parameter ξ was used. This parameter is a measure of the ratio between cross-association (solvation) energy A–B and self-association (association) energies A–A and B–B. It was shown that most important role at intermolecular interactions of oleic acid and ethyl oleate with triglycerides belonged to dispersion forces. Predominant contribution of hydrogen bonds in the interaction of oleic acid and ethyl oleate with ethanol was shown. The prediction of improving the effect of the cosolvents with temperature increasing was done, and it was confirmed by experimental results. The effect of oleic acid and ethyl oleate as cosolvents for homogenization of mixtures of sunflower oil and ethanol was investigated experimentally by studying the phase equilibria in the quasi-quaternary system triacylglycerols (sunflower oil) – ethanol – oleic acid – ethyl oleate at 30, 40, 50, 60 and 70 °C. The results of the experiments are presented in the form of phase diagrams of quasi-ternary boundary systems: triacylglycerols – oleic acid – ethanol and triacylglycerols – ethyl oleate – ethanol, and the phase diagrams of composition tetrahedron sections with five different ratios of components oleic acid: ethyl oleate. Generalization of the research results is presented in the form of polythermal phase diagram for the system triacylglycerols – ethanol – oleic acid – ethyl oleate. Solubility polytherms (from 30 to 70 °C) for the system triacylglycerols – ethanol – mixed cosolvent with different ratios of oleic acid and ethyl oleate were plotted

Copolymer-induced stabilizing effect of highly swollen hexagonal mesophases

We show quantitatively that tiny amounts of copolymer that decorate a oil/water interfaces can greatly enhance the stability of swollen surfactant hexagonal phases, comprising oil tubes regularly arranged in a water matrix. Such soft composite materials, whose both radius of the tubes and water channel between the tubes can be controlled independently over large ranges, offer a potential interest for the synthesis of mesoporous materials

The UK joint specialist societies guideline on the diagnosis and management of acute meningitis and meningococcal sepsis in immunocompetent adults.

Bacterial meningitis and meningococcal sepsis are rare conditions with high case fatality rates. Early recognition and prompt treatment saves lives. In 1999 the British Infection Society produced a consensus statement for the management of immunocompetent adults with meningitis and meningococcal sepsis. Since 1999 there have been many changes. We therefore set out to produce revised guidelines which provide a standardised evidence-based approach to the management of acute community acquired meningitis and meningococcal sepsis in adults. A working party consisting of infectious diseases physicians, neurologists, acute physicians, intensivists, microbiologists, public health experts and patient group representatives was formed. Key questions were identified and the literature reviewed. All recommendations were graded and agreed upon by the working party. The guidelines, which for the first time include viral meningitis, are written in accordance with the AGREE 2 tool and recommendations graded according to the GRADE system. Main changes from the original statement include the indications for pre-hospital antibiotics, timing of the lumbar puncture and the indications for neuroimaging. The list of investigations has been updated and more emphasis is placed on molecular diagnosis. Approaches to both antibiotic and steroid therapy have been revised. Several recommendations have been given regarding the follow-up of patients

Practical observations on the performance of bare silica in hydrophilic interaction compared with C18 reversed-phase liquid chromatography

The kinetic performance of a bare silica and C18 phase prepared from the same sub-2. μm and 3.5. μm base materials were compared in the HILIC and RP mode using both charged and neutral solutes. The HILIC column was characterised using the neutral solute 5-hydroxymethyluridine, the weak base cytosine, and the strong base nortriptyline, the latter having sufficient retention also in the RP mode to allow comparison of performance. Naphthalene was also used as a simple neutral substance to evaluate the RP column alone. The retention factors of all substances were adjusted to give similar values (k'. ~. 5.5) at their respective optimum linear velocities. Reduced van Deemter b-coefficients (determined by curve fitting and by the peak parking method, using a novel procedure involving switching to a dummy column) were significantly lower in HILIC for all substances compared with those found under RP conditions. Against expectation, c-coefficients were always lower in RP when compared with HILIC using sub-2. μm particles. While measurement of these coefficients is complicated by retention shifts caused by the influence of high pressure and by frictional heating effects, broadly similar results were obtained on larger particle (3.5. μm) phases. The mechanism of the separations was further investigated by examining the effect of buffer concentration on retention. It was concluded that HILIC can sometimes show somewhat inferior performance to RP for fast analysis at high mobile phase velocity, but clearly shows advantages when high column efficiencies, using longer columns at low flow velocity, are employed. The latter result is attributable to the lower viscosity of the mobile phase in HILIC and the reduced pressure requirement as well as the lower b-coefficients. © 2014 David V. McCalley