Which design principles unify the diversity of life on earth? To understand how biological designs emerged by natural selection, biomechanics studies organisms by applying engineering science and mechanics. Biomechanics studies life from molecules to ecosystems. Questions range ‘how do cells form tissue’, over ‘what shapes a muscle’ to ‘how do animals fly’ and ‘which mechanical constraints govern body shape and -dynamics when animals increase in size’. Biomechanics is applied not only to extant but also fossil organisms to reconstruct the way of life of extinct plants and animals.
Most biomechanists aim to unravel the building principles of nature by reverse engineering. But they also work in the opposite direction from biomechanical solutions to engineering designs. This field is known as biomimetics, and several examples are discussed in this issue. One famous example is George de Mestral’s invention of Velcro that was inspired by the cockleburs ingenious attachment mechanism. We are only beginning to exploit the rich source of stunning designs found in nature.
How to perform measurements in a hovering animal’s wake: Physical modelling of the vortex wake of the hawkmoth, Manduca sexta” (Tytell, E.D., and Ellington, C.P.)
How difficult is it to estimate forces on the wings of a flying insect or bird by measuring the airflow in its wake? Difficult, but not impossible, according to our study modelling the wake of a flying hawkmoth, and maybe easier on smaller animals. One of the major difficulties in studying animal flight has been that the wings often move too fast to make any useful measurements of the air flow around them. This is a sizeable problem, because insects and some small birds take advantage of a wide array of ‘high lift’ mechanisms that may be useful for future generations of flying machines. Rather than trying to make the difficult measurements around actual moving wings, most researchers have tried to deduce the forces on the wings from the airflow in the wake. While theoretically possible, this type of measurement had a setback in the ‘80s, when two studies on birds measured too little force to keep the animals aloft. Our study examines the feasibility of these measurements by studying the flow behind a highly simplified physical model of a hawkmoth. The trouble, it turns out, is turbulence. Large animals, including all but the smallest birds, produce wakes with substantial turbulence that causes the wake to loose strength rapidly, making it very difficult to back-calculate the forces around the wings. This back-calculation is not impossible, just difficult; but it is probably not feasible in a real experimental setup. Most insects, though, are small enough that their wakes are laminar, with smooth and even flow, which makes the wake strength stay constant for a long time. Our study shows that it is feasible to examine insects’ high lift mechanisms by observing the airflow in the wake behind them because of their laminar wakes.
Cyberkelp: An integrative approach to the modeling of flexible organisms (M. Denny and B. Hale)
Biomechanical models come in a variety of forms: conceptual models, physical models, and mathematical models (both of the sort written down on paper and the sort carried out on computers). There are model structures (such as the muscles that power insect flight muscle the tendons of rats’ tails), model organisms (such as the moth, Manduca sexta), even model systems of organisms (such as the communities that live on wave-swept rocky shores). These different types of models are typically employed separately, but their value often can be enhanced if their insights are combined. In this brief report we explore a particular example of such integration among models, as applied to a flexible marine alga, the giant bull kelp Nereocystis leutkeana. Because of these seaweeds’ large size and wave-swept habitat, it is difficult to make measurements on them directly. But because of their economic and ecological importance, it would be advantageous to understand how they work. A conceptual model (a submerged buoyant ball tethered to the seafloor by a rubbery string) serves as a template for the construction of a mathematical model of this model species of kelp. The validity of this numerical model is then tested in the laboratory using small physical models. The validated mathematical model is then used in conjunction with a computer-controlled testing apparatus to simulate the forces that would be placed on a real, full-size kelp in the ocean. This combination of models (what we call “cyberkelp”) allows us to experiment with a species that would otherwise be beyond our abilities.
Tim Watson | alfa
Ambush in a petri dish
24.11.2017 | Friedrich-Schiller-Universität Jena
Meadows beat out shrubs when it comes to storing carbon
23.11.2017 | Norwegian University of Science and Technology
High-precision measurement of the g-factor eleven times more precise than before / Results indicate a strong similarity between protons and antiprotons
The magnetic moment of an individual proton is inconceivably small, but can still be quantified. The basis for undertaking this measurement was laid over ten...
Heat from the friction of rocks caused by tidal forces could be the “engine” for the hydrothermal activity on Saturn's moon Enceladus. This presupposes that...
The WHO reports an estimated 429,000 malaria deaths each year. The disease mostly affects tropical and subtropical regions and in particular the African continent. The Fraunhofer Institute for Silicate Research ISC teamed up with the Fraunhofer Institute for Molecular Biology and Applied Ecology IME and the Institute of Tropical Medicine at the University of Tübingen for a new test method to detect malaria parasites in blood. The idea of the research project “NanoFRET” is to develop a highly sensitive and reliable rapid diagnostic test so that patient treatment can begin as early as possible.
Malaria is caused by parasites transmitted by mosquito bite. The most dangerous form of malaria is malaria tropica. Left untreated, it is fatal in most cases....
The formation of stars in distant galaxies is still largely unexplored. For the first time, astron-omers at the University of Geneva have now been able to closely observe a star system six billion light-years away. In doing so, they are confirming earlier simulations made by the University of Zurich. One special effect is made possible by the multiple reflections of images that run through the cosmos like a snake.
Today, astronomers have a pretty accurate idea of how stars were formed in the recent cosmic past. But do these laws also apply to older galaxies? For around a...
Just because someone is smart and well-motivated doesn't mean he or she can learn the visual skills needed to excel at tasks like matching fingerprints, interpreting medical X-rays, keeping track of aircraft on radar displays or forensic face matching.
That is the implication of a new study which shows for the first time that there is a broad range of differences in people's visual ability and that these...
15.11.2017 | Event News
15.11.2017 | Event News
30.10.2017 | Event News
24.11.2017 | Physics and Astronomy
24.11.2017 | Health and Medicine
24.11.2017 | Earth Sciences