We present a framework for modeling biological pumping organs based on coupled spiral elastic band geometries and active wave-propagating excitation mechanisms. Two pumping mechanisms are considered in detail by way of example: one of a simple tube, which represents a embryonic fish heart and another more complicated structure with the potential to model the adult human heart. Through finite element modeling different elastic contractions are induced in the band. For each version the pumping efficiency is measured and the dynamics are evaluated. We show that by combining helical shapes of muscle bands with a contraction wave it is possible not only to achieve efficient pumping, but also to create desired dynamics of the structure. As a result we match the function of the model pumps and their dynamics to physiological observations.
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http://dx.doi.org/10.1016/j.jtbi.2008.11.022 | DOI Listing |
J Exp Biol
December 2024
Biology Department, The University of Akron, Akron, OH 44325, USA.
Most orb-weaving spiders use static webs that deform only after flying prey hit the webs. However, ray spiders (Theridiosoma gemmosum) pull orb webs into cones that are loaded with enough elastic energy to snap back like slingshots at accelerations of up to 504 m s-2 once released. We test the hypothesis that ray spiders sense vibrations from flying insects to release their webs and capture prey in mid-flight.
View Article and Find Full Text PDFA single crystal sapphire component has been widely used in various high-tech fields because of its significant advantages such as high hardness, high stability, and excellent optical and mechanical properties, and has put forward high requirements for surface accuracy and quality. The existing sapphire polishing technology has problems such as low polishing efficiency, difficult control of polishing accuracy, and difficulty in removing surface defects and subsurface damage introduced by the front grinding process. Therefore, for the polishing and damage removal stage of sapphire optical components, the surface shape accuracy should be strictly controlled, especially for the surface shape accuracy after ultra-precision grinding.
View Article and Find Full Text PDFPhys Rev Lett
September 2024
International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China.
Chiral phases of matter, characterized by a definite handedness, abound in nature, ranging from the crystal structure of quartz to spiraling spin states in helical magnets. In 1T-TiSe_{2} a source of chirality has been proposed that stands apart from these classical examples as it arises from combined electronic charge and quantum orbital fluctuations. This may allow its chirality to be accessed and manipulated without imposing either structural or magnetic handedness.
View Article and Find Full Text PDFSci Rep
October 2024
Division of Cardiology, Department of Pediatrics, The Children's Hospital of Philadelphia, University of Pennsylvania, Philadelphia, PA, USA.
Heart failure (HF) is a life-threating cardiac disease that develops progressively for the reduced ability of the left ventricle (LV) to pump blood into the circulation during systole. HF can also develop in patients with a preserved systolic function, typically in presence of hypertrophic cardiomyopathy (HCM). This type of HF is sometimes termed as diastolic HF, but its biomechanical origin is still unclear.
View Article and Find Full Text PDFJ Hand Surg Eur Vol
August 2024
Royal United Hospitals Bath, Combe Park, Bath, Avon, UK.
This study assessed rotation control elastic strapping as a treatment for proximal phalanx spiral fractures in adults, with good clinical outcomes. This is a cheap, simple and reliable management technique that avoids potential operative complications.
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