scholarly journals Flying through gaps: how does a bird deal with the problem and what costs are there?

2021 ◽  
Vol 8 (8) ◽  
pp. 211072
Author(s):  
Per Henningsson
Keyword(s):  
Three Dimensional ◽  
Flight Speed ◽  
Power Relationship ◽  
Complex Environments ◽  
Wingbeat Frequency ◽  
Flight Duration ◽  
Safety Margins ◽  
Wide Range ◽  
In The Wild ◽  
Gap Width

Animals flying in the wild often show remarkable abilities to negotiate obstacles and narrow openings in complex environments. Impressive as these abilities are, this must result in costs in terms of impaired flight performance. In this study, I used a budgerigar as a model for studying these costs. The bird was filmed in stereo when flying through a wide range of gap widths from well above wingspan down to a mere 1/4 of wingspan. Three-dimensional flight trajectories were acquired and speed, wingbeat frequency and accelerations/decelerations were calculated. The bird used two different wing postures to get through the gaps and could use very small safety margins (down to 6 mm on either side) but preferred to use larger when gap width allowed. When gaps were smaller than wingspan, flight speed was reduced with reducing gap width down to half for the smallest and wingbeat frequency was increased. I conclude that flying through gaps potentially comes with multiple types of cost to a bird of which the main may be: (i) reduced flight speed increases the flight duration and hence the energy consumption to get from point A to B , (ii) the underlying U-shaped speed to power relationship means further cost from reduced flight speed, and associated with it (iii) elevated wingbeat frequency includes a third direct cost.

Addition of Artificial Loads to Long-Eared Bats Plecotus Auritus: Handicapping Flight Performance

1991 ◽  
Vol 161 (1) ◽  
pp. 285-298 ◽  
Author(s):  
PATSY M. HUGHES ◽  
JEREMY M. V. RAYNER
Keyword(s):  
Total Mass ◽  
Three Dimensional ◽  
Flight Speed ◽  
Wing Loading ◽  
Wingbeat Frequency ◽  
Cost Of Transport ◽  
In Captivity ◽  
Series Of Experiments ◽  
Predicted Values ◽  
Optimal Approach

A series of experiments is described in which two brown long-eared bats Plecotus auritus Linnaeus (Chiroptera: Vespertilionidae) were flown in a 1mx1mx4.5m flight enclosure at a range of body masses (n=9 experiments for a female bat, and n = 11 for a male bat). The highest three of these masses incorporated artificial loads. Stroboscopic stereophotogrammetry was used to make three-dimensional reconstructions (n=124) of the bats' flight paths. Over the entire range of experiments, wing loading was increased by 44% for the female and 46% for the male bat. Effects arising from captivity were controlled for: experiments at certain wing loadings were repeated after a period in captivity and the response to load was found to be unaltered. Flight speed fell with total mass M or with wing loading, varying as M−0.49 in the female and M−0.42 in the male bat. Wingbeat frequency increased with total mass or wing loading, varying as M0.61 in the female and M0.44in the male bat. Hence frequency, but not speed, changed with mass in the direction predicted by aerodynamic theory. These results were used in a mathematical model to predict wingbeat amplitude, flight power and cost of transport. The model was also used to estimate the optimal flight speeds Vmr and Vmp. The model predicted that amplitude increases with load. Measurements of wingbeat amplitude did not differ significantly from the predicted values. The observed flight speed was below the predicted minimum power speed Vmp (which increases with load), and diverged further from this with progressive loading. The increase in cost of flight calculated by the model over the range of wing loadings was approximately double that which it would have been had the bats adopted the optimal approach predicted by the model. The limitations inherent in the theoretical model, and the possible constraints acting on the animals, are discussed.

scholarly journals Simultaneous measurements of three-dimensional trajectories and wingbeat frequencies of birds in the field

2018 ◽  
Vol 15 (147) ◽  
pp. 20180653 ◽  
Author(s):  
Hangjian Ling ◽  
Guillam E. Mclvor ◽  
Geoff Nagy ◽  
Sepehr MohaimenianPour ◽  
Richard T. Vaughan ◽  
...  
Keyword(s):  
Stereo Matching ◽  
Imaging System ◽  
Three Dimensional ◽  
Bird Species ◽  
Three Dimensions ◽  
Natural Environments ◽  
Flight Performance ◽  
Stereo Imaging ◽  
Wingbeat Frequency ◽  
Wide Range

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. This system allows us to decouple body and wing motion, and thus measure not only velocities and accelerations but also wingbeat frequencies along the 3D trajectories of birds. We demonstrate these new methods by analysing six flocking events consisting of 50 to 360 jackdaws ( Corvus monedula ) and rooks ( Corvus frugilegus ) as well as 32 jackdaws and 6 rooks flying in isolated pairs or alone. Our method allows us to (i) measure flight speed and wingbeat frequency in different flying modes; (ii) characterize the U-shaped flight performance curve of birds in the wild, showing that wingbeat frequency reaches its minimum at moderate flight speeds; (iii) examine group effects on individual flight performance, showing that birds have a higher wingbeat frequency when flying in a group than when flying alone and when flying in dense regions than when flying in sparse regions; and (iv) provide a potential avenue for automated discrimination of bird species. We argue that the experimental method developed in this paper opens new opportunities for understanding flight kinematics and collective behaviour in natural environments.

Backpacking with the Saints

2015 ◽  
Author(s):  
Belden C. Lane
Keyword(s):  
American Southwest ◽  
Spiritual Practice ◽  
Spiritual Journey ◽  
Human Response ◽  
John Muir ◽  
Hildegard Of Bingen ◽  
Wide Range ◽  
Thich Nhat Hanh ◽  
In The Wild ◽  
John Of The Cross

Carrying only basic camping equipment and a collection of the world's great spiritual writings, Belden C. Lane embarks on solitary spiritual treks through the Ozarks and across the American Southwest. For companions, he has only such teachers as Rumi, John of the Cross, Hildegard of Bingen, Dag Hammarskjöld, and Thomas Merton, and as he walks, he engages their writings with the natural wonders he encounters--Bell Mountain Wilderness with Søren Kierkegaard, Moonshine Hollow with Thich Nhat Hanh--demonstrating how being alone in the wild opens a rare view onto one's interior landscape, and how the saints' writings reveal the divine in nature. The discipline of backpacking, Lane shows, is a metaphor for a spiritual journey. Just as the wilderness offered revelations to the early Desert Christians, backpacking hones crucial spiritual skills: paying attention, traveling light, practicing silence, and exercising wonder. Lane engages the practice not only with a wide range of spiritual writings--Celtic, Catholic, Protestant, Buddhist, Hindu, and Sufi Muslim--but with the fascination of other lovers of the backcountry, from John Muir and Ed Abbey to Bill Plotkin and Cheryl Strayed. In this intimate and down-to-earth narrative, backpacking is shown to be a spiritual practice that allows the discovery of God amidst the beauty and unexpected terrors of nature. Adoration, Lane suggests, is the most appropriate human response to what we cannot explain, but have nonetheless learned to love. An enchanting narrative for Christians of all denominations, Backpacking with the Saints is an inspiring exploration of how solitude, simplicity, and mindfulness are illuminated and encouraged by the discipline of backcountry wandering, and of how the wilderness itself becomes a way of knowing-an ecology of the soul.

Turbulent three-dimensional dielectric electrohydrodynamic convection between two plates

2012 ◽  
Vol 696 ◽  
pp. 228-262 ◽  
Author(s):  
A. Kourmatzis ◽  
J. S. Shrimpton
Keyword(s):  
Spatial Data ◽  
Three Dimensional ◽  
Reynolds Numbers ◽  
Two Dimensions ◽  
Three Dimensions ◽  
Energy Budgets ◽  
Turbulent Regime ◽  
Scalar Flux ◽  
Wide Range ◽  
Scalar Variance

AbstractThe fundamental mechanisms responsible for the creation of electrohydrodynamically driven roll structures in free electroconvection between two plates are analysed with reference to traditional Rayleigh–Bénard convection (RBC). Previously available knowledge limited to two dimensions is extended to three-dimensions, and a wide range of electric Reynolds numbers is analysed, extending into a fully inherently three-dimensional turbulent regime. Results reveal that structures appearing in three-dimensional electrohydrodynamics (EHD) are similar to those observed for RBC, and while two-dimensional EHD results bear some similarities with the three-dimensional results there are distinct differences. Analysis of two-point correlations and integral length scales show that full three-dimensional electroconvection is more chaotic than in two dimensions and this is also noted by qualitatively observing the roll structures that arise for both low (${\mathit{Re}}_{E} = 1$) and high electric Reynolds numbers (up to ${\mathit{Re}}_{E} = 120$). Furthermore, calculations of mean profiles and second-order moments along with energy budgets and spectra have examined the validity of neglecting the fluctuating electric field ${ E}_{i}^{\ensuremath{\prime} } $ in the Reynolds-averaged EHD equations and provide insight into the generation and transport mechanisms of turbulent EHD. Spectral and spatial data clearly indicate how fluctuating energy is transferred from electrical to hydrodynamic forms, on moving through the domain away from the charging electrode. It is shown that ${ E}_{i}^{\ensuremath{\prime} } $ is not negligible close to the walls and terms acting as sources and sinks in the turbulent kinetic energy, turbulent scalar flux and turbulent scalar variance equations are examined. Profiles of hydrodynamic terms in the budgets resemble those in the literature for RBC; however there are terms specific to EHD that are significant, indicating that the transfer of energy in EHD is also attributed to further electrodynamic terms and a strong coupling exists between the charge flux and variance, due to the ionic drift term.

scholarly journals Application of Dendrimers for Treating Parasitic Diseases

Pharmaceutics ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 343
Author(s):  
Veronica Folliero ◽  
Carla Zannella ◽  
Annalisa Chianese ◽  
Debora Stelitano ◽  
Annalisa Ambrosino ◽  
...  
Keyword(s):  
Drug Delivery ◽  
Water Solubility ◽  
Parasitic Infection ◽  
Three Dimensional ◽  
Medical Knowledge ◽  
High Ratio ◽  
Molecular Volume ◽  
Parasitic Infections ◽  
Parasitic Diseases ◽  
Wide Range

Despite advances in medical knowledge, parasitic diseases remain a significant global health burden and their pharmacological treatment is often hampered by drug toxicity. Therefore, drug delivery systems may provide useful advantages when used in combination with conventional therapeutic compounds. Dendrimers are three-dimensional polymeric structures, characterized by a central core, branches and terminal functional groups. These nanostructures are known for their defined structure, great water solubility, biocompatibility and high encapsulation ability against a wide range of molecules. Furthermore, the high ratio between terminal groups and molecular volume render them a hopeful vector for drug delivery. These nanostructures offer several advantages compared to conventional drugs for the treatment of parasitic infection. Dendrimers deliver drugs to target sites with reduced dosage, solving side effects that occur with accepted marketed drugs. In recent years, extensive progress has been made towards the use of dendrimers for therapeutic, prophylactic and diagnostic purposes for the management of parasitic infections. The present review highlights the potential of several dendrimers in the management of parasitic diseases.

scholarly journals An Overview on the Rheology, Mechanical Properties, Durability, 3D Printing, and Microstructural Performance of Nanomaterials in Cementitious Composites

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 2950
Author(s):  
Hongwei Song ◽  
Xinle Li
Keyword(s):  
Mechanical Properties ◽  
3D Printing ◽  
Three Dimensional ◽  
Cementitious Materials ◽  
Research Area ◽  
Cementitious Composites ◽  
Split Tensile Strength ◽  
Contour Crafting ◽  
Wide Range ◽  
Active Research

The most active research area is nanotechnology in cementitious composites, which has a wide range of applications and has achieved popularity over the last three decades. Nanoparticles (NPs) have emerged as possible materials to be used in the field of civil engineering. Previous research has concentrated on evaluating the effect of different NPs in cementitious materials to alter material characteristics. In order to provide a broad understanding of how nanomaterials (NMs) can be used, this paper critically evaluates previous research on the influence of rheology, mechanical properties, durability, 3D printing, and microstructural performance on cementitious materials. The flow properties of fresh cementitious composites can be measured using rheology and slump. Mechanical properties such as compressive, flexural, and split tensile strength reveal hardened properties. The necessary tests for determining a NM’s durability in concrete are shrinkage, pore structure and porosity, and permeability. The advent of modern 3D printing technologies is suitable for structural printing, such as contour crafting and binder jetting. Three-dimensional (3D) printing has opened up new avenues for the building and construction industry to become more digital. Regardless of the material science, a range of problems must be tackled, including developing smart cementitious composites suitable for 3D structural printing. According to the scanning electron microscopy results, the addition of NMs to cementitious materials results in a denser and improved microstructure with more hydration products. This paper provides valuable information and details about the rheology, mechanical properties, durability, 3D printing, and microstructural performance of cementitious materials with NMs and encourages further research.

scholarly journals Polymer cyclization for the emergence of hierarchical nanostructures

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Chaojian Chen ◽  
Manjesh Kumar Singh ◽  
Katrin Wunderlich ◽  
Sean Harvey ◽  
Colette J. Whitfield ◽  
...  
Keyword(s):  
Self Assembly ◽  
Three Dimensional ◽  
Hierarchical Structures ◽  
Structural Similarity ◽  
Vital Role ◽  
Nanomaterial Synthesis ◽  
Wide Range ◽  
Linear Poly ◽  
Polymer Folding ◽  
Dynamics Simulations

AbstractThe creation of synthetic polymer nanoobjects with well-defined hierarchical structures is important for a wide range of applications such as nanomaterial synthesis, catalysis, and therapeutics. Inspired by the programmability and precise three-dimensional architectures of biomolecules, here we demonstrate the strategy of fabricating controlled hierarchical structures through self-assembly of folded synthetic polymers. Linear poly(2-hydroxyethyl methacrylate) of different lengths are folded into cyclic polymers and their self-assembly into hierarchical structures is elucidated by various experimental techniques and molecular dynamics simulations. Based on their structural similarity, macrocyclic brush polymers with amphiphilic block side chains are synthesized, which can self-assemble into wormlike and higher-ordered structures. Our work points out the vital role of polymer folding in macromolecular self-assembly and establishes a versatile approach for constructing biomimetic hierarchical assemblies.

scholarly journals Automatic Reconstruction of Multi-Level Indoor Spaces from Point Cloud and Trajectory

Sensors ◽  
2021 ◽  
Vol 21 (10) ◽  
pp. 3493
Author(s):  
Gahyeon Lim ◽  
Nakju Doh
Keyword(s):  
Point Cloud ◽  
Dimensional Space ◽  
Three Dimensional ◽  
Reconstruction Method ◽  
Complex Environments ◽  
Indoor Space ◽  
Multi Level ◽  
Level Building ◽  
Indoor Spaces ◽  
Data Term

Remarkable progress in the development of modeling methods for indoor spaces has been made in recent years with a focus on the reconstruction of complex environments, such as multi-room and multi-level buildings. Existing methods represent indoor structure models as a combination of several sub-spaces, which are constructed by room segmentation or horizontal slicing approach that divide the multi-room or multi-level building environments into several segments. In this study, we propose an automatic reconstruction method of multi-level indoor spaces with unique models, including inter-room and inter-floor connections from point cloud and trajectory. We construct structural points from registered point cloud and extract piece-wise planar segments from the structural points. Then, a three-dimensional space decomposition is conducted and water-tight meshes are generated with energy minimization using graph cut algorithm. The data term of the energy function is expressed as a difference in visibility between each decomposed space and trajectory. The proposed method allows modeling of indoor spaces in complex environments, such as multi-room, room-less, and multi-level buildings. The performance of the proposed approach is evaluated for seven indoor space datasets.

scholarly journals Deciphering the Role of Residues Involved in Disorder-To-Order Transition Regions in Archaeal tRNA Methyltransferase 5

Genes ◽  
2021 ◽  
Vol 12 (3) ◽  
pp. 399
Author(s):  
Ambuj Srivastava ◽  
Dhanusha Yesudhas ◽  
Shandar Ahmad ◽  
M. Michael Gromiha
Keyword(s):  
Three Dimensional ◽  
Md Simulations ◽  
Order Transition ◽  
Free Form ◽  
Wild Type ◽  
Intrinsically Disordered ◽  
Intrinsically Disordered Regions ◽  
Type Complex ◽  
In The Wild ◽  
Trna Methyltransferase

tRNA methyltransferase 5 (Trm5) enzyme is an S-adenosyl methionine (AdoMet)-dependent methyltransferase which methylates the G37 nucleotide at the N1 atom of the tRNA. The free form of Trm5 enzyme has three intrinsically disordered regions, which are highly flexible and lack stable three-dimensional structures. These regions gain ordered structures upon the complex formation with tRNA, also called disorder-to-order transition (DOT) regions. In this study, we performed molecular dynamics (MD) simulations of archaeal Trm5 in free and complex forms and observed that the DOT residues are highly flexible in free proteins and become stable in complex structures. The energetic contributions show that DOT residues are important for stabilising the complex. The DOT1 and DOT2 are mainly observed to be important for stabilising the complex, while DOT3 is present near the active site to coordinate the interactions between methyl-donating ligands and G37 nucleotides. In addition, mutational studies on the Trm5 complex showed that the wild type is more stable than the G37A tRNA mutant complex. The loss of productive interactions upon G37A mutation drives the AdoMet ligand away from the 37th nucleotide, and Arg145 in DOT3 plays a crucial role in stabilising the ligand, as well as the G37 nucleotide, in the wild-type complex. Further, the overall energetic contribution calculated using MMPBSA corroborates that the wild-type complex has a better affinity between Trm5 and tRNA. Overall, our study reveals that targeting DOT regions for binding could improve the inhibition of Trm5.

scholarly journals A developmentally descriptive method for quantifying shape in gastropod shells

2020 ◽  
Vol 17 (163) ◽  
pp. 20190721
Author(s):  
J. Larsson ◽  
A. M. Westram ◽  
S. Bengmark ◽  
T. Lundh ◽  
R. K. Butlin
Keyword(s):  
Empirical Studies ◽  
Three Dimensional ◽  
Shell Shape ◽  
Large Set ◽  
Littorina Saxatilis ◽  
Shape Variation ◽  
Gastropod Shell ◽  
Geometric Morphometric ◽  
Wide Range ◽  
Descriptive Method

The growth of snail shells can be described by simple mathematical rules. Variation in a few parameters can explain much of the diversity of shell shapes seen in nature. However, empirical studies of gastropod shell shape variation typically use geometric morphometric approaches, which do not capture this growth pattern. We have developed a way to infer a set of developmentally descriptive shape parameters based on three-dimensional logarithmic helicospiral growth and using landmarks from two-dimensional shell images as input. We demonstrate the utility of this approach, and compare it to the geometric morphometric approach, using a large set of Littorina saxatilis shells in which locally adapted populations differ in shape. Our method can be modified easily to make it applicable to a wide range of shell forms, which would allow for investigations of the similarities and differences between and within many different species of gastropods.

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