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10,561 results for “mechanics”
Casting voids in nickel superalloy and the mechanical behaviour under room temperature tensile deformation
<p>This repository contains the original X-ray tomography data presented in the publication 'Casting voids in nickel superalloy and the mechanical behaviour under room temperature tensile deformation'.</p> <p>The XCT data were collected using Zeiss Xradia Versa 520 instrument from Henry Moseley X-ray Imaging facility at the University of Manchester. Access to the instrument was granted by Henry Royce Institute through PhD access funding scheme for Zhuocheng Xu. Data to produce Figure8 and Figure9 are also uploaded.</p>
Different types of kinase inhibitors with experimentally confirmed mechanism of action
<p>A data set of ATP-competitive and allosteric inhibitors of human protein kinases with mechanisms of action confirmed by X-ray crystallography is provided. Data were acquired from the Protein Data Bank (PDB) and the KLIFS, ProfKin, ASD, and ChEMBL databases, curated, and organized. The composition of the data set is detailed in the accompanying readme.txt file.</p> <p> </p> <p> </p>
Dataset: The role of social costs as a mechanism enforcing the honesty of ultraviolet-reflecting signals in a lizard
<p>Here are the data associated with the study entitled "The role of social costs as a mechanism enforcing the honesty of ultraviolet-reflecting signals in a lizard<strong>"</strong> authored by Anna Kawamoto, Jean-François Le Galliard, and Arnaud Badiane and published in <em>Biological Journal of the Linnean Society</em>.</p> <p>Four different data sets are provided and the Notes.xlsx file explains the content of these data sets.</p> <p>We also added three short videos showing typical lizards' behaviours scored in this study.</p> <p> </p>
Heterothermy as a mechanism to offset energetic costs of environmental and homeostatic perturbations
<p>Environmental and biotic pressures impose homeostatic costs on all organisms. The energetic costs of maintaining high body temperatures (<i>T</i><sub>b</sub>) render endotherms sensitive to pressures that increase foraging costs. In response, some mammals become more heterothermic to conserve energy. We measured <i>T</i><sub>b</sub> in banner-tailed kangaroo rats (<i>Dipodomys spectabilis</i>) to test and disentangle the effects of air temperature and moonlight (a proxy for predation risk) on thermoregulatory homeostasis. We further perturbed homeostasis in some animals with chronic corticosterone (CORT) via silastic implants. Heterothermy increased across summer, consistent with the predicted effect of lunar illumination (and predation), and in the direction opposite to the predicted effect of environmental temperatures. The effect of lunar illumination was also evident within nights as animals maintained low <i>T</i><sub>b</sub> when the moon was above the horizon. The pattern was accentuated in CORT-treated animals, suggesting they adopted an even further heightened risk-avoidance strategy that might impose reduced foraging and energy intake. Still, CORT-treatment did not affect body condition over the entire study, indicating kangaroo rats offset decreases in energy intake through energy savings associated with heterothermy. Environmental conditions receive the most attention in studies of thermoregulatory homeostasis, but we demonstrated here that biotic factors can be more important and should be considered in future studies.</p>
Data for the article "Direct imaging of current-induced antiferromagnetic switching revealing a pure thermomagnetoelastic switching mechanism"
<p>Data for the article "Direct imaging of current-induced antiferromagnetic switching revealing a pure thermomagnetoelastic switching mechanism" (<a href="https://pubs.acs.org/doi/full/10.1021/acs.nanolett.0c03367">Direct Imaging of Current-Induced Antiferromagnetic Switching Revealing a Pure Thermomagnetoelastic Switching Mechanism in NiO | Nano Letters (acs.org)</a> and <a href="https://arxiv.org/abs/2008.05219">[2008.05219] Direct imaging of current-induced antiferromagnetic switching revealing a pure thermomagnetoelastic switching mechanism (arxiv.org)</a>)</p>
Mechanical Engineering: An International Journal (MEIJ)
<p>CALL FOR PAPERS...!!!!</p> <p> </p> <p><strong>Mechanical Engineering: An International Journal (MEIJ)</strong></p> <p> </p> <p><a href="http://airccse.com/meij/index.html"><strong>http://airccse.com/meij/index.html</strong></a></p> <p> </p> <p><strong>ISSN: 2349 – 2651</strong></p> <p> </p> <p><strong>Submission Deadline:</strong> <strong>January 30</strong> <strong>, 2021</strong></p> <p> </p> <p><strong>CONTACT US : </strong><a href="mailto:meijjournal@yahoo.com"><strong>meijjournal@yahoo.com</strong></a><strong> or </strong><a href="mailto:meij@airccse.com"><strong>meij@airccse.com</strong></a></p> <p> </p> <p><strong>Submission Link</strong> : <a href="https://airccse.com/submission/home.html"><strong>https://airccse.com/submission/home.html</strong></a></p> <p> </p> <p> </p> <p> </p> <p> </p> <p> </p>
Data from: Experimental demonstration of the mechanism of steady-state microbunching
<p>A mechanism called steady-state microbunching (SSMB) has been proposed to generate high-repetition, high-power coherent radiation in an electron storage ring. Such a novel phton source will provide unprecedented opportunities for accelerator photon science and technological applications. In this paper, we report the first demonstration of the mechanism of SSMB. This demonstration represents a crucial step towards the implementation of an SSMB-based high-repetition, high-power photon source.</p>
Data from: Induced phenological avoidance: a neglected defense mechanism against seed predation in plants
<p>1. Flowering phenology is an important life history trait affecting plant reproductive performance and is influenced by various abiotic and biotic factors. Pre-dispersal seed predation and pollination are expected to impose counteracting selection pressure on flowering phenology, with pre-dispersal seed predation expected to favor off-peak flowering and pollination to favor synchronous flowering. <br> 2. Here we studied the effect of pre-dispersal seed predation by the beetle Byturus ochraceus, a specialist seed herbivore, on the flowering phenology of Geum urbanum. This forest understorey plant species is self-pollinating, so that the influence of seed predation can be studied independent from pollination. We measured in detail the timing and predation rate of individual flowers during two consecutive years in more than 60 individuals. We tested the hypotheses that pre-dispersal seed predation exerts selection for within-season compensatory flowering as well as for induced phenological avoidance in the following season.<br> 3. We found no indication for compensatory flowering within a growing season, but plants that experienced predation shifted their flowers to the end of the flowering season the subsequent year. This induced phenological avoidance points to a plastic response to pre-dispersal seed predation that may be adaptive. Importantly, the delay in flower production came at a cost, since flowers later in the season had a reduced seed output, presumably because of increasing light limitation following forest canopy closure. <br> 4. Synthesis: Herbivory by specialist enemies can cause serious fitness decline in hosts. We here show that induced shifts in phenology can form an important defense strategy against pre-dispersal seed predation. The induced mismatches between herbivore and host phenology are anticipated to be adaptive when herbivory is predictable across successive flowering periods.</p>
Herding mechanisms to maintain the cohesion of a harem group: two interaction phases during herding
<p>In animal groups, individual interactions achieve coordinated movements to maintain cohesion. In horse harem groups, herding<br> is a behavior in which males chase females from behind; it is considered to assist with group cohesiveness. However,<br> the mechanisms by which the individuals move to maintain group cohesion are unknown. We applied novel non-invasive<br> methods of drone filming and video tracking to observe horse movements in the field with high temporal and spatial resolution.<br> We tracked all group members and drew trajectories. We analyzed the movements of females and found two phases<br> of interactions based on their timing of movement initiation. The females that moved first were those nearest to the herding<br> male, while the movement initiation of the later females was determined by the distance from the nearest moving female, not<br> by the distance from the herding male. These interactions are unique among animal group movements and might represent a<br> herding mechanism responsible for maintaining group cohesion. This might be due to long-term stable relationships within<br> a harem group and strong social bonds between females. This study showed that the combination of drone filming and video<br> tracking is a useful method for analyzing the movements of animals simultaneously in high resolution.</p>
Data from: Varieties of the highly dispersible and hypervariable tree, Metrosideros polymorpha, differ in response to mechanical stress and light across a sharp ecotone
PREMISE OF THE STUDY: The drivers of isolation between sympatric populations of long-lived and highly-dispersible conspecific plants are not well understood. In the Hawaiian Islands the landscape-dominant tree, Metrosideros polymorpha, displays extraordinary phenotypic differences among sympatric varieties despite high dispersibility of its pollen and seeds, thereby presenting a unique opportunity to investigate how disruptive selection alone can maintain incipient forms. Stenophyllous M. polymorpha var. newellii is a recently evolved tree endemic to the waterways of east Hawai'i Island that shows striking neutral genetic differentiation from its ancestor, wet-forest var. glaberrima, despite sympatry of these forms. We looked for evidence for, and drivers of, differential local adaptation of these varieties across the range of var. newellii. METHODS: For paired populations of these varieties, we compared seedling performance under contrasting light conditions and a strong water current characteristic of the riparian zone. We also conducted a reciprocal transplant experiment and contrasted adult leaf anatomy. KEY RESULTS: Results suggest that the riparian zone is harsh and that selection involving the mechanical stress of rushing water, and secondarily light, lead to significant reciprocal immigrant inviability in adjacent forest and riparian environments. The strongest adaptive divergence between varieties was seen in leaves and seedlings from the site with the sharpest ecotone, coincident with the strongest genetic isolation of var. newellii observed previously. CONCLUSIONS: These findings suggest that disruptive selection across a sharp ecotone contributes to the maintenance of an incipient riparian ecotype from within a continuous population of a long-lived and highly dispersible tree species.
Data from: Arena size modulates functional responses via behavioral mechanisms
Laboratory-based functional response experiments, in which foraging rates are measured across a range of resource densities, are central for determining trophic interaction strength. Historically these experiments often are performed in arbitrarily sized arenas, with larger sized organisms generally used in larger arenas. However, arena size influences foraging rates and therefore also estimates of the functional response parameters, particularly space clearance rate (attack rate). We hypothesized that non-random movement within arenas by predators and prey may explain this effect. To test this hypothesis, we video-recorded Schizocosa ocreata wolf spiders (predators) and flightless Drosophila melanogaster prey in circular arenas of three different sizes to reveal thigmotactic behavior. We then estimated foraging rates and space clearance rates from feeding trials performed at a single, low prey density in three differently-size arenas in either annular (ring-shaped) or circular arenas. Annular arenas mitigated the effects of predator and prey aggregation and thus controlled the experienced prey density near arena edges. Unlike the circular arenas, annular arenas produced similar foraging rates and space clearance rate estimates across arena sizes, confirming that it is the increased density of prey along edges that generates the previously observed arena size effect. Our results provide a key insight into how animal behavior and experimental design must be considered for the accurate interpretation of foraging rates, both when considering standalone functional responses and when making comparisons across experiments.
Disentangling the assembly mechanisms of ant cuticular bacterial communities of two Amazonian ant species sharing a common arboreal nest
<p>Bacteria living on the cuticle of ants are generally studied for their protective role against pathogens, especially in the clade of fungus-growing ants. However, little is known of the diversity of cuticular bacteria in other ant host species, as well as of the mechanisms leading to the composition of these communities. Here, we used 16S rRNA gene amplicon sequencing to study the influence of host species, species interactions, and the pool of bacteria from the environment on the assembly of cuticular bacterial communities on two phylogenetically distant Amazonian ant species that frequently nest together inside the roots system of epiphytic plant<i>s</i>, <i>Camponotus femoratus</i> and <i>Crematogaster levior</i>. Our results show that 1) the vast majority of the bacterial community on the cuticle is shared with the nest, suggesting that most bacteria on the cuticle are acquired through environmental acquisition, 2) 5.2% and 2.0% OTUs are respectively specific to <i>Camponotus femoratus</i> and <i>Crematogaster levior</i>, likely representing their respective core cuticular bacterial community, and 3) 3.6% of OTUs are shared between the two ant species. Additionally, mass spectrometry metabolomics analysis of metabolites on the cuticle of ants, which excludes the detection of cuticular hydrocarbons produced by the host, were conducted to evaluate correlations among bacterial OTUs and m/z ion mass. Although some positive and negative correlations are found, the cuticular chemical composition was weakly species specific which supports that cuticular bacterial communities are prominently environmentally acquired. Overall, our results suggest that the environment is the dominant source of bacteria found on the cuticle of ants.</p>
Data from: Examining the microclimate hypothesis in Amazonian birds: indirect tests of the 'visual constraints' mechanism
Proposed mechanisms for the decline of terrestrial and understory insectivorous birds in the tropics include a related subset that together has been termed the "microclimate hypothesis." One prediction from this hypothesis is that sensitivity to bright light environments discourages birds of the dimly lit rainforest interior from using edges, gaps, or disturbed forest. Using a hierarchical Bayesian framework and capture data across time and space, we tested this by first determining vulnerability based on differences in within-species capture rates between disturbed and undisturbed forest for 64 bird species at the Biological Dynamics of Forest Fragments Project in central Amazonian Brazil. We found that 35 species (55%) were vulnerable to anthropogenic habitat degradation, whereas only four (6%) were more commonly captured in degraded forest. To infer visual sensitivity, we then examined two different characters: eye size (maximum pupil diameter) relative to body mass and the initiation time of dawn song, which presumably reflects a species' visual capacity under low light intensities. We predicted that species with large relative eye sizes and birds with earlier dawn songs would exhibit increased vulnerability in degraded habitats with bright light. Contrary to our predictions, however, vulnerability was positively correlated with the mean start time of dawn song. This indicates that species that wait to initiate dawn song are also more vulnerable to habitat degradation. After correcting for body size, there was no effect of eye size on vulnerability. Together, our results do not provide quantitative support for the light sensitivity mechanism of the microclimate hypothesis. More sensitive, experimental tests, such as behavioral assays with controlled light environments, especially in a comparative framework, are needed to rigorously evaluate the role of light sensitivity as an aspect of the microclimate hypothesis among Neotropical birds.
Data from: Evaluating mechanisms of diversification in a Guineo-Congolian tropical forest frog using demographic model selection
The accumulation of biodiversity in tropical forests can occur through multiple allopatric and parapatric models of diversification, including forest refugia, riverine barriers and ecological gradients. Considerable debate surrounds the major diversification process, particularly in the West African Lower Guinea forests, which contain a complex geographic arrangement of topographic features and historical refugia. We used genomic data to investigate alternative mechanisms of diversification in the Gaboon forest frog, Scotobleps gabonicus, by first identifying population structure and then performing demographic model selection and spatially explicit analyses. We found that a majority of population divergences are best explained by allopatric models consistent with the forest refugia hypothesis and involve divergence in isolation with subsequent expansion and gene flow. These population divergences occurred simultaneously and conform to predictions based on climatically stable regions inferred through ecological niche modelling. Although forest refugia played a prominent role in the intraspecific diversification of S. gabonicus, we also find evidence for potential interactions between landscape features and historical refugia, including major rivers and elevational barriers such as the Cameroonian Volcanic Line. We outline the advantages of using genomewide variation in a model-testing framework to distinguish between alternative allopatric hypotheses, and the pitfalls of limited geographic and molecular sampling. Although phylogeographic patterns are often species-specific and related to life-history traits, additional comparative studies incorporating genomic data are necessary for separating shared historical processes from idiosyncratic responses to environmental, climatic and geological influences on diversification.
Disentangling the mechanisms underpinning disturbance-mediated invasion data
<p><span>Disturbances can play a major role in biological invasions: by destroying biomass, they alter habitat and resource abundances. Previous field studies suggest that disturbance-mediated invader success is a consequence of resource influxes, but the importance of other potential covarying causes, notably the opening up of habitats, have yet to be directly tested. Using experimental populations of the bacterium <i>Pseudomonas fluorescens </i>we determined the relative importance of disturbance-mediated habitat opening and resource influxes, plus any interaction between them, for invader success of two ecologically distinct morphotypes. Resource addition increased invasibility, while habitat opening had little impact or interacted with resource addition. Both invaders behaved similarly, despite occupying different ecological niches in the microcosms. Treatment also affected the composition of the resident population, which further affected invader success. Our results provide experimental support for the observation that resource input is a key mechanism through which disturbance increases invasibility. </span></p>
Data from: Mechanical feedback and robustness of apical constrictions in Drosophila embryo ventral furrow formation
<p>Formation of the ventral furrow in the Drosophila embryo relies on the apical constriction of cells in the ventral region to produce bending forces that drive tissue invagination. Recently [J Phys Condens Matter. 2016;28(41):414021], we observed that apical constrictions during the initial phase of ventral furrow formation produce elongated patterns of cellular constriction chains prior to invagination, and argued that these are indicative of tensile stress feedback. Here, we quantitatively analyze the constriction patterns preceding ventral furrow formation and find that they are consistent with the predictions of our active-granular-fluid model of a monolayer of mechanically coupled stress-sensitive constricting particles. Our model shows that tensile feedback causes constriction chains to develop along underlying precursor tensile stress chains that gradually strengthen with subsequent cellular constrictions. As seen in both our model and available optogenetic experiments, this mechanism allows constriction chains to penetrate or circumvent zones of reduced cell contractility, thus increasing the robustness of ventral furrow formation to spatial variation of cell contractility by rescuing cellular constrictions in the disrupted regions.</p>
Ecological mechanisms explaining interactions within plant-hummingbird networks: morphological matching increases towards lower latitudes
<p><a name="ab4">Interactions between species are influenced by different ecological mechanisms, such as morphological matching, phenological overlap, and species abundances</a>. <a name="Ab1"></a><a name="ab5">How</a> these mechanisms explain interaction frequencies across environmental gradients remains poorly understood. Consequently, we also know little about the mechanisms that drive the geographical patterns in network structure, such as complementary specialization and modularity. Here, we use data on morphologies, phenologies and abundances to explain interaction frequencies between hummingbirds and plants at a large geographic scale. <a name="ab2">For 24 quantitative networks sampled throughout the Americas, we found that</a> the tendency of species to interact with morphologically matching partners contributed to specialized and modular network structures. Morphological matching best explained interaction frequencies in networks found closer to the equator and in areas with low temperature seasonality. When comparing the three ecological mechanisms within networks, we found that both morphological matching and phenological overlap generally outperformed abundances in the explanation of interaction frequencies. Together, these findings provide insights into the ecological mechanisms that underlie geographical patterns in resource specialization. Notably, our results highlight morphological constraints on interactions as a potential explanation for increasing resource specialization towards lower latitudes.</p>
Impact of intercept trap type on plume structure: a potential mechanism for differential performance of intercept trap designs for Monochamus species
<p>Studies have demonstrated that semiochemical-baited intercept traps differ in their performance for sampling insects, but we have an incomplete understanding of how and why intercept trap design effects vary among insects. This can significantly delay both the development of new and optimization of existing survey and detection tools. The development of a mechanistic understanding of why trap performance varies within and among species would mitigate this delay. The primary objective of this study was to develop methods to characterize and compare the odor plumes associated with intercept traps that differ in their performance for forest Coleoptera. We released CO<sub>2</sub> and measured fluctuations of this tracer gas from 175-point locations arranged in a 2-by-3-by-2-m grid cuboid downwind of a standard multiple-funnel, a modified multiple-funnel, a panel, a canopy malaise trap, and a blank control (i.e., no trap) in a greenhouse. Significant differences in trapping efficacy between these different trap designs were observed for <i>Monochamus scutellatus</i> (Say) and <i>Monochamus notatus</i> (Drury) in a field trial. Significant differences were also observed in how CO<sub>2</sub> accumulated in time at different positions downwind among these different trap designs. Turbulent dispersion is the dominant force structuring odor plumes and creates intermittency in the odor plume that is important for sustained upwind flight in insects. Methodological and instrumental limitations resulted in the inability to determine instantaneous plume structures and vortex shedding frequencies for different intercept trap designs. Although we observed differences in the odor plumes emanating downwind of the different intercept trap designs, we were unable to reconcile these differences with capture rates of the different trap designs for <i>M. scutellatus</i> and <i>M. notatus</i>.</p>
A genetic mechanism for sexual dichromatism in birds
<p>Sexual dichromatism — a difference in coloration between males and females — is central to the study of ornamentation, mate choice, and sexual selection. Here, we show that carotenoid-based dichromatism in mosaic canaries, a hybrid product between the sexually dichromatic red siskin and monochromatic canaries, is controlled by the carotenoid-cleaving enzyme Beta-Carotene Oxygenase 2 (<i>BCO2</i>). Dichromatism in mosaic canaries is explained by differential carotenoid degradation in the integument of each sex, rather than sex-specific variation in physiological functions such as pigment uptake or transport. Transcriptome analyses suggest that carotenoid degradation in the integument might be a common mechanism contributing to sexual dichromatism in other finches. Our findings demonstrate how differences in ornamental coloration between sexes can evolve through simple molecular mechanisms controlled by genes of major effect.</p>
Data from: The hatching mechanism of 130-million-year-old insects: an association of neonates, egg shells and egg bursters in Lebanese amber
Hatching is a pivotal moment in the life of most animals. Diverse chemical, behavioural and mechanical methods have evolved in metazoans to break the egg membranes. Among them, many arthropod and vertebrate embryos hatch using ephemeral, frequently convergent structures known as egg bursters. However, the evolutionary processes by which hatching mechanisms and related embryonic structures became established in deep time are poorly understood due to a nearly complete absence from the fossil record. Herein we describe an exceptional c. 130‐million‐year‐old association in Lebanese amber composed of multiple neonate green lacewing larvae, Tragichrysa ovoruptora gen. et sp. nov. (Neuroptera, Chrysopoidea), and conspecific egg remains. Egg bursters with a serrated blade bearing a short process are attached to three longitudinally split egg shells. Embryos of extant green lacewing relatives (Chrysopidae) utilize this egg burster morphotype to open a vertical slit on the egg, after which the burster is moulted and left joined to the empty egg shell. Additionally, the new larval species has extremely elongate dorsal tubercles, an adaptation to carry exogenous debris for protection and camouflage also known from other Cretaceous chrysopoids but absent in modern relatives. The present discovery demonstrates that the hatching mechanism of modern green lacewings was established in the chrysopoid lineage by the Early Cretaceous and proves through direct fossil evidence how some morphological traits related to hatching and linked behaviours, at least in insect embryos, have been subject to a high degree of evolutionary conservatism.
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These curated guides explain access requirements, typical timelines, costs, and reuse considerations for widely used research datasets.
Allen Brain Atlas
Allen Brain Atlas is an Allen Institute collection of brain map atlases, datasets, APIs, and analysis tools covering mouse, human, and non-human primate brain resources.
Annotated Behaviour and Observability Dataset (ABODe)
ABODe is a University of Edinburgh DataShare dataset for behavior classification in group-housed mice using home-cage video, identities, bounding boxes, ground-plate positions, and annotator labels.
DANDI Archive for NWB datasets
DANDI is a BRAIN Initiative archive for publishing and sharing neurophysiology data, including electrophysiology, optophysiology, and behavioral data packaged as NWB and related standards.
International Brain Laboratory public data
The International Brain Laboratory public data releases expose standardized mouse decision-making experiments, including Neuropixels recordings, widefield calcium imaging, behavior, and session metadata accessed through the ONE API.
OpenNeuro
OpenNeuro is a free, open platform for sharing neuroimaging datasets, with public search, dataset pages, and download paths for web, S3, DataLad, and the OpenNeuro CLI.