Escapement-Based Movements as Positioning Mechanisms: Design and Modelling

This work has been triggered by an industrial project targeting the design of a mechatronic injector for the medical field. Injections are usually performed using a syringe, a quite clumsy tool that transforms the injection task in a positioning one. The quality of injections can be enhanced by using devices that help control the injected dose, or the injection rate, but usually at the cost of a slower operation, a reduced manoeuvrability, or a short battery life for electrically-powered devices. The idea was therefore to provide a cordless miniaturised injector capable of managing the dosage as well as injection rate according to the user's desires, with the constraint that it should have a long battery life. This is why escapementbased movements are investigated in this work. Such stepper movements, where a regulator controls the speed at which a stock of mechanical energy is emptied, have been used for centuries in clockwork. Purely mechanical devices, the regulators are designed to work at a given frequency, with the stability of said frequency as the main objective. For the discussed application, the use of an electronic regulator permits variable injection rates and simplifies dosage control. Beingmostly used in clockwork, escapement-based movements are hardly mentioned, let alone studied, outside this field in the literature. This research is aimed at filling this void to provide engineers with the basics for the design of escapement-based movements, using Pahl & Beitz's design methodology. First of all, a general structure of suchmovements is proposed. Using functional analysis, a canvas for the requirements specification of a movement is given. To ensure an efficient and fast evaluation of the quality of a solution at any stage of the development, modelling and design tools are suggested. The industrial project is then used as a case study that exemplifies the concepts introduced. The requirements, a selected functioning principle, and the main technical solutions are described. The application of the modelling tools is done in two parts, representing two subsystems designed concurrently but separately: the purely mechanical part of the movement that includes the escapement, and the mechatronic regulator. The dynamic and energetic performances of both subsystems are modelled, using relevant techniques. Analytical models characterise the mechanical part of the system, using advantageously the stepper nature of the system. Because they are analytical, the models require very limited computational resources and are thus extremely convenient design tools. They also permit a stochastic study of the influence of manufacturing tolerances on said performance. Regulators, in particular electronically-controlled ones, are then discussed. An optimisation strategy for highly constrained problems is proposed. It consists in first optimising a set of input parameters towards acceptable values for the constraints. Once one or more sets of parameters respecting the constraints are found, these sets are used as initial points for the actual optimisation of the objectives. The efficacy of this strategy is demonstrated by an example. Finally, a prototype of the devised escapement-based movement is presented. It is used to establish the validity of the developedmodels, but also demonstrate the capabilities of the retained functioning principle

Stretchable Materials for Robust Soft Actuators towards Assistive Wearable Devices

Soft actuators made from elastomeric active materials can find widespread potential implementation in a variety of applications ranging from assistive wearable technologies targeted at biomedical rehabilitation or assistance with activities of daily living, bioinspired and biomimetic systems, to gripping and manipulating fragile objects, and adaptable locomotion. In this manuscript, we propose a novel two-component soft actuator design and design tool that produces actuators targeted towards these applications with enhanced mechanical performance and manufacturability. Our numerical models developed using the finite element method can predict the actuator behavior at large mechanical strains to allow efficient design iterations for system optimization. Based on two distinctive actuator prototypes’ (linear and bending actuators) experimental results that include free displacement and blocked-forces, we have validated the efficacy of the numerical models. The presented extensive investigation of mechanical performance for soft actuators with varying geometric parameters demonstrates the practical application of the design tool, and the robustness of the actuator hardware design, towards diverse soft robotic systems for a wide set of assistive wearable technologies, including replicating the motion of several parts of the human body

A single epidermal stem cell strategy for safe ex vivo gene therapy.

There is a widespread agreement from patient and professional organisations alike that the safety of stem cell therapeutics is of paramount importance, particularly for ex vivo autologous gene therapy. Yet current technology makes it difficult to thoroughly evaluate the behaviour of genetically corrected stem cells before they are transplanted. To address this, we have developed a strategy that permits transplantation of a clonal population of genetically corrected autologous stem cells that meet stringent selection criteria and the principle of precaution. As a proof of concept, we have stably transduced epidermal stem cells (holoclones) obtained from a patient suffering from recessive dystrophic epidermolysis bullosa. Holoclones were infected with self-inactivating retroviruses bearing a COL7A1 cDNA and cloned before the progeny of individual stem cells were characterised using a number of criteria. Clonal analysis revealed a great deal of heterogeneity among transduced stem cells in their capacity to produce functional type VII collagen (COLVII). Selected transduced stem cells transplanted onto immunodeficient mice regenerated a non-blistering epidermis for months and produced a functional COLVII. Safety was assessed by determining the sites of proviral integration, rearrangements and hit genes and by whole-genome sequencing. The progeny of the selected stem cells also had a diploid karyotype, was not tumorigenic and did not disseminate after long-term transplantation onto immunodeficient mice. In conclusion, a clonal strategy is a powerful and efficient means of by-passing the heterogeneity of a transduced stem cell population. It guarantees a safe and homogenous medicinal product, fulfilling the principle of precaution and the requirements of regulatory affairs. Furthermore, a clonal strategy makes it possible to envision exciting gene-editing technologies like zinc finger nucleases, TALENs and homologous recombination for next-generation gene therapy

Population Dynamics of the Rubber Plantation Litter Beetle Luprops tristis, in Relation to Annual Cycle of Foliage Phenology of Its Host, the Para Rubber Tree, Hevea brasiliensis

The population dynamics of the rubber plantation litter beetle, Luprops tristis Fabricius 1801 (Coleoptera: Tenebrionidae) was assessed in relation to the phenology of leaf shedding and defoliation pattern of para rubber trees, Hevea brasiliensis Müll. Arg (Malpighiales: Euphorbiaceae), during a two year study period. The abundance of adults, larvae and pupae per 1m2 of litter sample was recorded. Post dormancy beetles appeared in leaf litter following annual leaf shedding, whereas larvae, pupae and teneral adults were present after leaf flush. No stages were recorded from plantations following the summer rains until the annual litter fall in the next season. Parental adults peaked at the time of leaf sprouting and tender leaf fall. Larvae and teneral adults peaked at the time of premature fall of green leaves and flowers. Teneral adults of six age classes were recorded and all entered dormancy irrespective of the feeding time available to each age class. Females outnumbered males in the parent generation, while the sex ratio of new generation adults was not biased towards either sex. The phenological stages of rubber trees included leaf fall in late December and early January, leaf sprouting and new leaf production in January and flowering in February. All feeding stages of L. tristis peaked in abundance when premature leaves are most abundant in the leaf litter. Prediction of the timing of appearance of various developmental stages of L. tristis in plantations, invasion into buildings and intensity of population build up in rubber belts is possible by tracking the phenology of leaf fall in rubber plantations, time of return of post dormancy adults and the onset of summer rainfall. Perfect synchrony was recorded between the field return of parental adults with annual leaf shedding, the oviposition phase of parental adults with tender leaf fall at the time of leaf sprouting, and larval and teneral adult stages with premature fall of leaves. Premature leaf availability is suggested as contributing to the reproductive efficiency of parental adults, the survival of early developmental stages and of new generation adults during dormancy

A Comparison of the Pitfall Trap, Winkler Extractor and Berlese Funnel for Sampling Ground-Dwelling Arthropods in Tropical Montane Cloud Forests

Little is known about the ground-dwelling arthropod diversity in tropical montane cloud forests (TMCF). Due to unique habitat conditions in TMCFs with continuously wet substrates and a waterlogged forest floor along with the innate biases of the pitfall trap, Berlese funnel and Winkler extractor are certain to make it difficult to choose the most appropriate method to sample the ground-dwelling arthropods in TMCFs. Among the three methods, the Winkler extractor was the most efficient method for quantitative data and pitfall trapping for qualitative data for most groups. Inclusion of floatation method as a complementary method along with the Winkler extractor would enable a comprehensive quantitative survey of ground-dwelling arthropods. Pitfall trapping is essential for both quantitative and qualitative sampling of Diplopoda, Opiliones, Orthoptera, and Diptera. The Winkler extractor was the best quantitative method for Psocoptera, Araneae, Isopoda, and Formicidae; and the Berlese funnel was best for Collembola and Chilopoda. For larval forms of different insect orders and the Acari, all the three methods were equally effective

Revision des Pselaphostomus et Pselaphogenius ibériques (Col. Pselaphidae)

Ii m'a semblé plus utile, plutót que de décrire isolément quelques espèces nouvelles, de reviser soigneusement tous les Pselaphostomus et Pselaphogenius de la péninsule ibérique. Je me suis efforcé d'étudier les types et de réunir à peu près tous les exemplaires capturés en Espagne et au Portugal. C'est ainsi que j'ai pu disposer pour cette revision, gräce à l'obligeance de nombreux collègues que je remercie très chaleureusement, gräce aussi aux subsides qui m'ont été généreusement alloués par le Fonds national suisse de la Recherche scientifique pour mes chasses dans la péninsule ibérique, 289 exemplaires du genre Pse'aphostomus et 82 exemplaires du genre Pselaphogenius.Peer reviewe

Description d\u27un Col\ue9opt\ue8re Scydm\ue9nie cavernicole de la Nouvelle-Cal\ue9donie

Volume: 88Start Page: 459End Page: 46