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Journal of the Royal Society, Interface

Hannah J Williams, Andrew J King, Olivier Duriez, Luca Börger, Emily L C Shepard
Vultures are thought to form networks in the sky, with individuals monitoring the movements of others to gain up-to-date information on resource availability. While it is recognized that social information facilitates the search for carrion, how this facilitates the search for updrafts, another critical resource, remains unknown. In theory, birds could use information on updraft availability to modulate their flight speed, increasing their airspeed when informed on updraft location. In addition, the stylized circling behaviour associated with thermal soaring is likely to provide social cues on updraft availability for any bird operating in the surrounding area...
November 7, 2018: Journal of the Royal Society, Interface
Per Henningsson, Lasse Jakobsen, Anders Hedenström
In this study, we explicitly examine the aerodynamics of manoeuvring flight in animals. We studied brown long-eared bats flying in a wind tunnel while performing basic sideways manoeuvres. We used particle image velocimetry in combination with high-speed filming to link aerodynamics and kinematics to understand the mechanistic basis of manoeuvres. We predicted that the bats would primarily use the downstroke to generate the asymmetries for the manoeuvre since it has been shown previously that the majority of forces are generated during this phase of the wingbeat...
November 7, 2018: Journal of the Royal Society, Interface
Soumya Banerjee, S Jonathan Chapman
The thymus is the primary organ for the generation of naive T cells, a key component of the immune system. Tolerance of T cells to self is achieved primarily in the thymic medulla, where immature T cells (thymocytes) sample self-peptides presented by medullary thymic epithelial cells (mTECs). A sufficiently strong interaction activates the thymocytes leading to negative selection. A key question of current interest is whether there is any structure in the manner in which mTECs present peptides: can any mTEC present any peptide at any time, or are there particular patterns of correlated peptide presentation? We investigate this question using a mathematical model of negative selection...
November 7, 2018: Journal of the Royal Society, Interface
Cody T Ross, Monique Borgerhoff Mulder, Seung-Yun Oh, Samuel Bowles, Bret Beheim, John Bunce, Mark Caudell, Gregory Clark, Heidi Colleran, Carmen Cortez, Patricia Draper, Russell D Greaves, Michael Gurven, Thomas Headland, Janet Headland, Kim Hill, Barry Hewlett, Hillard S Kaplan, Jeremy Koster, Karen Kramer, Frank Marlowe, Richard McElreath, David Nolin, Marsha Quinlan, Robert Quinlan, Caissa Revilla-Minaya, Brooke Scelza, Ryan Schacht, Mary Shenk, Ray Uehara, Eckart Voland, Kai Willführ, Bruce Winterhalder, John Ziker
No abstract text is available yet for this article.
October 31, 2018: Journal of the Royal Society, Interface
Franck J Vernerey, Tong Shen, Shankar Lalitha Sridhar, Robert J Wagner
Active networks are omnipresent in nature, from the molecular to the macro-scale. In this study, we explore the mechanical behaviour of fire ant aggregations, closely knit swarms that display impressive dynamics culminating with the aggregations' capacity to self-heal and adapt to the environment. Although the combined elasticity and rheology of the ant aggregation can be characterized by phenomenological mechanical models (e.g. linear Maxwell or Kelvin-Voigt model), it is not clear how the behaviour of individual ants affects the aggregations' emerging responses...
October 31, 2018: Journal of the Royal Society, Interface
Steffen Waldherr
Heterogeneity among individual cells is a characteristic and relevant feature of living systems. A range of experimental techniques to investigate this heterogeneity is available, and multiple modelling frameworks have been developed to describe and simulate the dynamics of heterogeneous populations. Measurement data are used to adjust computational models, which results in parameter and state estimation problems. Methods to solve these estimation problems need to take the specific properties of data and models into account...
October 31, 2018: Journal of the Royal Society, Interface
Susannah Bourne Worster, P J Hore
Evidence is accumulating to support the hypothesis that some animals use light-induced radical pairs to detect the direction of the Earth's magnetic field. Cryptochrome proteins seem to be involved in the sensory pathway but it is not yet clear if they are the magnetic sensors: they could, instead, play a non-magnetic role as signal transducers downstream of the primary sensor. Here we propose an experiment with the potential to distinguish these functions. The principle is to use superparamagnetic nanoparticles to disable any magnetic sensing role by enhancing the electron spin relaxation of the radicals so as to destroy their spin correlation...
October 31, 2018: Journal of the Royal Society, Interface
Thomas C Player, P J Hore
It has been suggested that 31 P nuclear spins in Ca9 (PO4 )6 molecules could form the basis of a quantum mechanism for neural processing in the brain. A fundamental requirement of this proposal is that spins in different Ca9 (PO4 )6 molecules can become entangled and remain so for periods (estimated at many hours) that hugely exceed typical 31 P spin relaxation times. Here, we consider the coherent and incoherent spin dynamics of Ca9 (PO4 )6 arising from dipolar and scalar spin-spin interactions and derive an upper bound of 37 min on the entanglement lifetime under idealized physiological conditions...
October 31, 2018: Journal of the Royal Society, Interface
Goylette F Chami, Narcis B Kabatereine, Edridah M Tukahebwa, David W Dunne
In low-income countries, complex comorbidities and weak health systems confound disease diagnosis and treatment. Yet, data-driven approaches have not been applied to develop better diagnostic strategies or to tailor treatment delivery for individuals within rural poor communities. We observed symptoms/diseases reported within three months by 16 357 individuals aged 1+ years in 17 villages of Mayuge District, Uganda. Symptoms were mapped to the Human Phenotype Ontology. Comorbidity networks were constructed...
October 31, 2018: Journal of the Royal Society, Interface
Simone Cenci, Serguei Saavedra
Biotic interactions are expected to play a major role in shaping the dynamics of ecological systems. Yet, quantifying the effects of biotic interactions has been challenging due to a lack of appropriate methods to extract accurate measurements of interaction parameters from experimental data. One of the main limitations of existing methods is that the parameters inferred from noisy, sparsely sampled, nonlinear data are seldom uniquely identifiable. That is, many different parameters can be compatible with the same dataset and can generalize to independent data equally well...
October 31, 2018: Journal of the Royal Society, Interface
Victor Manuel Ortega-Jiménez, Stacey A Combes
Turbulent flows associated with thermal convection are common in areas where the ground is heated by solar radiation, fermentation or other processes. However, it is unknown how these flow instabilities affect the locomotion of small insects, like fruit flies, that inhabit deserts and urban landscapes where surface temperatures can reach extreme values. We quantified flight performance of fruit flies ( Drosophila melanogaster ) traversing a chamber through still air and turbulent Rayleigh-Bénard convection cells produced by a vertical temperature gradient...
October 24, 2018: Journal of the Royal Society, Interface
Hangjian Ling, Guillam E Mclvor, Geoff Nagy, Sepehr MohaimenianPour, Richard T Vaughan, Alex Thornton, Nicholas T Ouellette
Tracking the movements of birds in three dimensions is integral to a wide range of problems in animal ecology, behaviour and cognition. Multi-camera stereo-imaging has been used to track the three-dimensional (3D) motion of birds in dense flocks, but precise localization of birds remains a challenge due to imaging resolution in the depth direction and optical occlusion. This paper introduces a portable stereo-imaging system with improved accuracy and a simple stereo-matching algorithm that can resolve optical occlusion...
October 24, 2018: Journal of the Royal Society, Interface
A Stewart, R Hunt, R Mitchell, V Muhawenimana, C A M E Wilson, J A Jackson, J Cable
For fish, there can be multiple consequences of parasitic infections, including the physical impacts on swimming and the pathological costs of infection. This study used the three-spined stickleback ( Gasterosteus aculeatus ) and the ectoparasitic fish louse, Argulus foliaceus , to assess both physical (including form drag and mass) and pathological effects of infection. Both sustained (prolonged swimming within an open channel flume) and burst (C-start) swimming performance were measured on individual fish before (trials 1-2) and after infection (trials 3-5)...
October 24, 2018: Journal of the Royal Society, Interface
Matthew N George, Benjamin Pedigo, Emily Carrington
Marine mussels ( Mytilus spp.) attach to a wide variety of surfaces underwater using a network of byssal threads, each tipped with a protein-based adhesive plaque that uses the surrounding seawater environment as a curing agent. Plaques undergo environmental post-processing, requiring a basic seawater pH be maintained for up to 8 days for the adhesive to strengthen completely. Given the sensitivity of plaques to local pH conditions long after deposition, we investigated the effect of other aspects of the seawater environment that are known to vary in nearshore habitats on plaque curing...
October 24, 2018: Journal of the Royal Society, Interface
Kevin T Du Clos, Amy Lang, Sean Devey, Philip J Motta, Maria Laura Habegger, Brad J Gemmell
Shark skin has been shown to reduce drag in turbulent boundary layer flows, but the flow control mechanisms by which it does so are not well understood. Drag reduction has generally been attributed to static effects of scale surface morphology, but possible drag reduction effects of passive or active scale actuation, or 'bristling', have been recognized more recently. Here, we provide the first direct documentation of passive scale bristling due to reversing, turbulent boundary layer flows. We recorded and analysed high-speed videos of flow over the skin of a shortfin mako shark, Isurus oxyrinchus These videos revealed rapid scale bristling events with mean durations of approximately 2 ms...
October 24, 2018: Journal of the Royal Society, Interface
Jianing Wu, Yichao Zhao, Yunshu Zhang, David Shumate, Stephanie Braccini Slade, Scott V Franklin, David L Hu
Wild African elephants are voracious eaters, consuming 180 g of food per minute. One of their methods for eating at this speed is to sweep food into a pile and then pick it up. In this combined experimental and theoretical study, we elucidate the elephant's unique method of picking up a pile of food by compressing it with its trunk. To grab the smallest food items, the elephant forms a joint in its trunk, creating a pillar up to 11 cm tall that it uses to push down on food. Using a force sensor, we show the elephant applies greater force to smaller food pieces, in a manner that is required to solidify the particles into a lump solid, as calculated by Weibullian statistics...
October 24, 2018: Journal of the Royal Society, Interface
Víctor Sellés de Lucas, Hugo Dutel, Susan E Evans, Flora Gröning, Alana C Sharp, Peter J Watson, Michael J Fagan
The falx cerebri and the tentorium cerebelli are two projections of the dura mater in the cranial cavity which ossify to varying degrees in some mammalian species. The idea that the ossification of these structures may be necessary to support the loads arising during feeding has been proposed and dismissed in the past, but never tested quantitatively. To address this, a biomechanical model of a domestic cat ( Felis silvestris catus ) skull was created and the material properties of the falx and tentorium were varied for a series of loading regimes incorporating the main masticatory and neck muscles during biting...
October 24, 2018: Journal of the Royal Society, Interface
Xunjie Yu, Raphaël Turcotte, Francesca Seta, Yanhang Zhang
Microstructural deformation of elastic lamellae plays important roles in maintaining arterial tissue homeostasis and regulating vascular smooth muscle cell fate. Our study unravels the underlying microstructural origin that enables elastic lamellar layers to evenly distribute the stresses through the arterial wall caused by intraluminal distending pressure, a fundamental requirement for tissue and cellular function. A new experimental approach was developed to quantify the spatial organization and unfolding of elastic lamellar layers under pressurization in mouse carotid arteries by coupling physiological extension-inflation and multiphoton imaging...
October 17, 2018: Journal of the Royal Society, Interface
Samuel T Fabian, Mary E Sumner, Trevor J Wardill, Sergio Rossoni, Paloma T Gonzalez-Bellido
When aiming to capture a fast-moving target, animals can follow it until they catch up, or try to intercept it. In principle, interception is the more complicated strategy, but also more energy efficient. To study whether simple feedback controllers can explain interception behaviours by animals with miniature brains, we have reconstructed and studied the predatory flights of the robber fly Holcocephala fusca and killer fly Coenosia attenuata Although both species catch other aerial arthropods out of the air, Holcocephala contrasts prey against the open sky, while Coenosia hunts against clutter and at much closer range...
October 17, 2018: Journal of the Royal Society, Interface
C Honrado, L Ciuffreda, D Spencer, L Ranford-Cartwright, H Morgan
Although malaria is the world's most life-threatening parasitic disease, there is no clear understanding of how certain biophysical properties of infected cells change during the malaria infection cycle. In this article, we use microfluidic impedance cytometry to measure the dielectric properties of Plasmodium falciparum -infected red blood cells ( i- RBCs) at specific time points during the infection cycle. Individual parasites were identified within i- RBCs using green fluorescent protein (GFP) emission. The dielectric properties of cell sub-populations were determined using the multi-shell model...
October 17, 2018: Journal of the Royal Society, Interface
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