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Total 656 results found since Jan 2013.
Hummingbird flight stability and control in freestream turbulent winds RESEARCH ARTICLE
Sridhar Ravi, James D. Crall, Lucas McNeilly, Susan F. Gagliardi, Andrew A. Biewener, and Stacey A. CombesAirflow conditions close to the Earth's surface are often complex, posing challenges to flight stability and control for volant taxa. Relatively little is known about how well flying animals can contend with complex, adverse air flows, or about the flight-control mechanisms employed by animals to mitigate wind disturbances. Several recent studies have examined flight in the unsteady von Kármán vortex streets that form behind cylinders, generating flow disturbances that are predictable in space and time; t...
Source: Journal of Experimental Biology - March 12, 2015 Category: Biology Authors: Ravi, S., Crall, J. D., McNeilly, L., Gagliardi, S. F., Biewener, A. A., Combes, S. A. Tags: RESEARCH ARTICLE Source Type: research
Lift vs. drag based mechanisms for vertical force production in the smallest flying insects
Publication date: 7 November 2015 Source:Journal of Theoretical Biology, Volume 384 Author(s): S.K. Jones, R. Laurenza, T.L. Hedrick, B.E. Griffith, L.A. Miller We used computational fluid dynamics to determine whether lift- or drag-based mechanisms generate the most vertical force in the flight of the smallest insects. These insects fly at Re on the order of 4–60 where viscous effects are significant. Detailed quantitative data on the wing kinematics of the smallest insects is not available, and as a result both drag- and lift-based strategies have been suggested as the mechanisms by which these insects stay alof...
Source: Journal of Theoretical Biology - September 6, 2015 Category: Biology Source Type: research
Underwater flight by the planktonic sea butterfly RESEARCH ARTICLE
David W. Murphy, Deepak Adhikari, Donald R. Webster, and Jeannette Yen
In a remarkable example of convergent evolution, we show that the zooplanktonic sea butterfly Limacina helicina ‘flies’ underwater in the same way that very small insects fly in the air. Both sea butterflies and flying insects stroke their wings in a characteristic figure-of-eight pattern to produce lift, and both generate extra lift by peeling their wings apart at the beginning of the power stroke (the well-known Weis-Fogh ‘clap-and-fling’ mechanism). It is highly surprising to find a zooplankter ‘mimicking’ insect f...
Source: Journal of Experimental Biology - February 17, 2016 Category: Biology Authors: Murphy, D. W., Adhikari, D., Webster, D. R., Yen, J. Tags: RESEARCH ARTICLE Source Type: research
Wings as impellers: Honey bees co-opt flight system to induce nest ventilation and disperse pheromones RESEARCH ARTICLE
Jacob M. Peters, Nick Gravish, and Stacey A. Combes Honey bees (Apis mellifera) are remarkable fliers that regularly carry heavy loads of nectar and pollen, supported by a flight system – the wings, thorax and flight muscles - that one might assume is optimized for aerial locomotion. However, honey bees also use this system to perform other crucial tasks that are unrelated to flight. When ventilating the nest, bees grip the surface of the comb or nest entrance and fan their wings to drive airflow through the nest, and a similar wing-fanning behavior is used to disperse volatile pheromones from the Nasonov gland. In o...
Source: Journal of Experimental Biology - April 12, 2017 Category: Biology Authors: Peters, J. M., Gravish, N., Combes, S. A. Tags: RESEARCH ARTICLE Source Type: research
Wings as impellers: honey bees co-opt flight system to induce nest ventilation and disperse pheromones RESEARCH ARTICLE
Jacob M. Peters, Nick Gravish, and Stacey A. Combes
Honey bees (Apis mellifera) are remarkable fliers that regularly carry heavy loads of nectar and pollen, supported by a flight system – the wings, thorax and flight muscles – that one might assume is optimized for aerial locomotion. However, honey bees also use this system to perform other crucial tasks that are unrelated to flight. When ventilating the nest, bees grip the surface of the comb or nest entrance and fan their wings to drive airflow through the nest, and a similar wing-fanning behavior is used to disperse volatile pheromones from the Nasonov glan...
Source: Journal of Experimental Biology - June 14, 2017 Category: Biology Authors: Peters, J. M., Gravish, N., Combes, S. A. Tags: RESEARCH ARTICLE Source Type: research
The added mass forces in insect flapping wings
Publication date: 21 January 2018 Source:Journal of Theoretical Biology, Volume 437 Author(s): Longgui Liu, Mao Sun The added mass forces of three-dimensional (3D) flapping wings of some representative insects, and the accuracy of the often used simple two-dimensional (2D) method, are studied. The added mass force of a flapping wing is calculated by both 3D and 2D methods, and the total aerodynamic force of the wing is calculated by the CFD method. Our findings are as following. The added mass force has a significant contribution to the total aerodynamic force of the flapping wings during and near the stroke reversals, an...
Source: Journal of Theoretical Biology - November 4, 2017 Category: Biology Source Type: research
Ferulic acid-loaded nanostructured lipid carriers: A promising nanoformulation against the ischemic neural injuries
Publication date: 15 January 2018 Source:Life Sciences, Volume 193 Author(s): Parichehr Hassanzadeh, Elham Arbabi, Fatemeh Atyabi, Rassoul Dinarvand Aims Treatment of the ischemic stroke has remained a major healthcare challenge. The phenolic compound, ferulic acid (FA), has shown promising antioxidant and neuroprotective effects, however, low bioavailability may negatively affect its efficiency. This, prompted us to incorporate FA into the nanostructured lipid carriers (FA-NLCs) and evaluate its therapeutic potential in in vitro and in vivo models of ischemic stroke. Main methods FA-NLCs were prepared by high-pressure ho...
Source: Life Sciences - December 22, 2017 Category: Biology Source Type: research
4-((5-(Tert-butyl)-3-chloro-2-hydroxybenzyl) amino)-2-hydroxybenzoic acid protects against oxygen-glucose deprivation/reperfusion injury
Publication date: 1 July 2018 Source:Life Sciences, Volume 204 Author(s): Yuexinzi Jin, Xuelian Tang, Xiang Cao, Linjie Yu, Jian Chen, Haoran Zhao, Yan Chen, Lijuan Han, Xinyu Bao, Fei Li, Yun Xu Aims Oxidative stress is one of the most important pathological mechanisms which could aggravate ischemic stroke injury. In order to seek for better treatment therapies to alleviate stroke injury, novel chemicals have been synthetized. In the present study, a new compound 4-((5-(tert-butyl)-3-chloro-2-hydroxybenzyl) amino)-2- hydroxybenzoic acid, named LX009, was used to determine whether it could reduce the oxidative stress caus...
Source: Life Sciences - May 18, 2018 Category: Biology Source Type: research
Contraction of atrial smooth muscle reduces cardiac output in perfused turtle hearts RESEARCH ARTICLE
William Joyce, Michael Axelsson, and Tobias Wang Unusual undulations in resting tension (tonus waves) were described in isolated atria from freshwater turtle more than a century ago. These tonus waves were soon after married with the histological demonstration of a rich layer of smooth muscle on the luminal side of the atrial wall. Research thereafter waned and the functional significance of this smooth muscle has remained obscure. Here we provide evidence that contraction of the smooth muscle in the atria may be able to change cardiac output in turtle hearts. In in situ perfused hearts of the red-eared slider turtle (Trac...
Source: Journal of Experimental Biology - February 20, 2019 Category: Biology Authors: Joyce, W., Axelsson, M., Wang, T. Tags: RESEARCH ARTICLE Source Type: research
Pectoral fin kinematics and motor patterns are shaped by fin ray mechanosensation during steady swimming in Scarus quoyi RESEARCH ARTICLE
Brett R. Aiello, Aaron M. Olsen, Chris E. Mathis, Mark W. Westneat, and Melina E. Hale For many species of fishes, rhythmic movement of the pectoral fins, or forelimbs, drives locomotion. In terrestrial vertebrates, normal limb-based rhythmic gaits require ongoing modulation with limb mechanosensors. Given the complexity of the fluid environment and dexterity of fish swimming through it, we hypothesize that mechanosensory modulation is also critical to normal fin-based swimming. Here we examine the role of sensory feedback from the pectoral fin rays and membrane on the neuromuscular control and kinematics of pectoral fin-b...
Source: Journal of Experimental Biology - December 19, 2019 Category: Biology Authors: Aiello, B. R., Olsen, A. M., Mathis, C. E., Westneat, M. W., Hale, M. E. Tags: RESEARCH ARTICLE Source Type: research
Therapeutic treatment with vitamin C reduces focal cerebral ischemia-induced brain infarction in rats by attenuating disruptions of blood brain barrier and cerebral neuronal apoptosis.
In this study we demonstrated that parenteral administration of vitamin C significantly improved neurological deficits and reduced brain infarction and brain edema by attenuating the transient middle cerebral artery occlusion (tMCAO)-induced nitrosative stress, inflammatory responses, and the resultant disruptions of blood brain barrier and cerebral neuronal apoptosis. These results suggest that parenteral administration of vitamin C has potential as an adjuvant agent with intravenous thrombolysis or endovascular thrombectomy in acute treatment of ischemic stroke.
PMID: 32450129 [PubMed - as supplied by publisher]
Source: Free Radical Biology and Medicine - May 21, 2020 Category: Biology Authors: Chang CY, Chen JY, Wu MH, Hu ML Tags: Free Radic Biol Med Source Type: research
Flight muscle power increases with strain amplitude and decreases with cycle frequency in zebra finches (Taeniopygia guttata) RESEARCH ARTICLE
Joseph W. Bahlman, Vikram B. Baliga, and Douglas L. Altshuler Birds that use high flapping frequencies can modulate aerodynamic force by varying wing velocity, which is primarily a function of stroke amplitude and wingbeat frequency. Previous measurements from zebra finches (Taeniopygia guttata) flying across a range of speeds in a wind tunnel demonstrate that although the birds modulated both wingbeat kinematic parameters, they exhibited greater changes in stroke amplitude. These two kinematic parameters contribute equally to aerodynamic force, so the preference for modulating amplitude over frequency may instead derive f...
Source: Journal of Experimental Biology - October 12, 2020 Category: Biology Authors: Bahlman, J. W., Baliga, V. B., Altshuler, D. L. Tags: RESEARCH ARTICLE Source Type: research
