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
A Map of the Cell’s Power Station
18.08.2017 | Albert-Ludwigs-Universität Freiburg im Breisgau
On the way to developing a new active ingredient against chronic infections
21.08.2017 | Deutsches Zentrum für Infektionsforschung
Whether you call it effervescent, fizzy, or sparkling, carbonated water is making a comeback as a beverage. Aside from quenching thirst, researchers at the University of Illinois at Urbana-Champaign have discovered a new use for these "bubbly" concoctions that will have major impact on the manufacturer of the world's thinnest, flattest, and one most useful materials -- graphene.
As graphene's popularity grows as an advanced "wonder" material, the speed and quality at which it can be manufactured will be paramount. With that in mind,...
Physicists at the University of Bonn have managed to create optical hollows and more complex patterns into which the light of a Bose-Einstein condensate flows. The creation of such highly low-loss structures for light is a prerequisite for complex light circuits, such as for quantum information processing for a new generation of computers. The researchers are now presenting their results in the journal Nature Photonics.
Light particles (photons) occur as tiny, indivisible portions. Many thousands of these light portions can be merged to form a single super-photon if they are...
For the first time, scientists have shown that circular RNA is linked to brain function. When a RNA molecule called Cdr1as was deleted from the genome of mice, the animals had problems filtering out unnecessary information – like patients suffering from neuropsychiatric disorders.
While hundreds of circular RNAs (circRNAs) are abundant in mammalian brains, one big question has remained unanswered: What are they actually good for? In the...
An experimental small satellite has successfully collected and delivered data on a key measurement for predicting changes in Earth's climate.
The Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) CubeSat was launched into low-Earth orbit on Nov. 11, 2016, in order to test new...
A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg presents evidence of the coexistence of superconductivity and “charge-density-waves” in compounds of the poorly-studied family of bismuthates. This observation opens up new perspectives for a deeper understanding of the phenomenon of high-temperature superconductivity, a topic which is at the core of condensed matter research since more than 30 years. The paper by Nicoletti et al has been published in the PNAS.
Since the beginning of the 20th century, superconductivity had been observed in some metals at temperatures only a few degrees above the absolute zero (minus...
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