The slings and arrows of communication on nanotechnology

According to numerous surveys the perceived risk of nanotechnology is low and most people feel that the benefits outweigh the risks. This article provides greater insight into risk perception and concludes that the positive attitude to nanotechnology is based not on knowledge but on hope and fascination. The perceived risk is low because of a lack of vivid and frightening images of possible hazards. If news flashes were to link nanotechnology to concrete hazards or actual harm to people, attitudes might suddenly change. Risk communication faces the problem of dealing with a public at large that has little or no knowledge about the technology. As it takes time and extensive additional research to develop appropriate communication strategies and disseminate them to the relevant institutions, this exercise should be started immediately

Coupled Systems of Differential-Algebraic and Kinetic Equations with Application to the Mathematical Modelling of Muscle Tissue

We consider a coupled system composed of a linear differential-algebraic equation (DAE) and a linear large-scale system of ordinary differential equations where the latter stands for the dynamics of numerous identical particles. Replacing the discrete particles by a kinetic equation for a particle density, we obtain in the mean-field limit the new class of partially kinetic systems. We investigate the influence of constraints on the kinetic theory of those systems and present necessary adjustments. We adapt the mean-field limit to the DAE model and show that index reduction and the mean-field limit commute. As a main result, we prove Dobrushin's stability estimate for linear systems. The estimate implies convergence of the mean-field limit and provides a rigorous link between the particle dynamics and their kinetic description. Our research is inspired by mathematical models for muscle tissue where the macroscopic behaviour is governed by the equations of continuum mechanics, often discretised by the finite element method, and the microscopic muscle contraction process is described by Huxley's sliding filament theory. The latter represents a kinetic equation that characterises the state of the actin-myosin bindings in the muscle filaments. Linear partially kinetic systems are a simplified version of such models, with focus on the constraints.Comment: 32 pages, 18 figure

Stretching skeletal muscle: chronic muscle lengthening through sarcomerogenesis.

Skeletal muscle responds to passive overstretch through sarcomerogenesis, the creation and serial deposition of new sarcomere units. Sarcomerogenesis is critical to muscle function: It gradually re-positions the muscle back into its optimal operating regime. Animal models of immobilization, limb lengthening, and tendon transfer have provided significant insight into muscle adaptation in vivo. Yet, to date, there is no mathematical model that allows us to predict how skeletal muscle adapts to mechanical stretch in silico. Here we propose a novel mechanistic model for chronic longitudinal muscle growth in response to passive mechanical stretch. We characterize growth through a single scalar-valued internal variable, the serial sarcomere number. Sarcomerogenesis, the evolution of this variable, is driven by the elastic mechanical stretch. To analyze realistic three-dimensional muscle geometries, we embed our model into a nonlinear finite element framework. In a chronic limb lengthening study with a muscle stretch of 1.14, the model predicts an acute sarcomere lengthening from 3.09[Formula: see text]m to 3.51[Formula: see text]m, and a chronic gradual return to the initial sarcomere length within two weeks. Compared to the experiment, the acute model error was 0.00% by design of the model; the chronic model error was 2.13%, which lies within the rage of the experimental standard deviation. Our model explains, from a mechanistic point of view, why gradual multi-step muscle lengthening is less invasive than single-step lengthening. It also explains regional variations in sarcomere length, shorter close to and longer away from the muscle-tendon interface. Once calibrated with a richer data set, our model may help surgeons to prevent muscle overstretch and make informed decisions about optimal stretch increments, stretch timing, and stretch amplitudes. We anticipate our study to open new avenues in orthopedic and reconstructive surgery and enhance treatment for patients with ill proportioned limbs, tendon lengthening, tendon transfer, tendon tear, and chronically retracted muscles

Communicating Food Risk-Benefit Assessments: Edible Insects as Red Meat Replacers

Risk-benefit Assessment (RBA) is an emerging methodology in the area of Food and Nutrition that offers a simultaneous evaluation of both risks and benefits linked to dietary choices. Communication of such research to consumers may present a challenge due to the dual nature of RBA. We present a case study of a communication strategy developed for the NovRBA-project. The NovRBA-project (Novel foods as red meat replacers—an insight using Risk Benefit Assessment methods) performed a risk-benefit assessment to evaluate the overall health impact of substituting red meat (beef) by a novel food (house cricket), considering the microbial, toxicological and nutritional characteristics of the respective dietary choices. A literature review of risk perceptions and acceptance of beef and insects as food formed the basis of the communication strategy for the study's results, drawing on environmental and emotional as well as health-related motivations to consume or avoid either food and considering the sociodemographic characteristics of likely consumers. Challenges and future directions for consumer protection organizations communicating findings of risk-benefit analyses on food safety are discussed. Copyright © 2021 Boehm, Borzekowski, Ververis, Lohmann and Böl

Sarcomere units in striated muscle.

<p>Sarcomeres consist of a parallel arrangement of thick filaments of myosin (gray) sliding along thin filaments of actin (green). They are embedded between Z-lines (red), which appear as dark lines under the transmission electron microscope. In healthy muscle, through the dynamic assembly and disassembly, individual sarcomere units maintain an optimal operating length. Adopted with permission from <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0045661#pone.0045661-Gktepe1" target="_blank">[16]</a>.</p

Sarcomere lengths in chronically stretched skeletal muscle.

<p>Computationally predicted sarcomere lengths agree nicely with experimentally measured sarcomere lengths with errors on the order of the experimental standard deviation <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0045661#pone.0045661-Matano1" target="_blank">[8]</a>.</p

Single-step stretching vs multi-step stretching of skeletal muscle.

<p>A total stretch of is applied ad hoc (left) and gradually (right). Sarcomerogenesis is simulated for over period of eight weeks.</p