scholarly journals Risso's dolphins perform spin dives to target deep-dwelling prey

2021 ◽  
Vol 8 (12) ◽  
Author(s):  
Fleur Visser ◽  
Onno A. Keller ◽  
Machiel G. Oudejans ◽  
Douglas P. Nowacek ◽  
Annebelle C. M. Kok ◽  
...  
Keyword(s):  
Foraging Behaviour ◽  
Foraging Strategy ◽  
Near Surface ◽  
Grampus Griseus ◽  
Deep Diving ◽  
Foraging Decisions ◽  
Deep Scattering Layer ◽  
Fundamental Insight ◽  
Dense Aggregation ◽  
Insight Into

Foraging decisions of deep-diving cetaceans can provide fundamental insight into food web dynamics of the deep pelagic ocean. Cetacean optimal foraging entails a tight balance between oxygen-conserving dive strategies and access to deep-dwelling prey of sufficient energetic reward. Risso's dolphins ( Grampus griseus ) displayed a thus far unknown dive strategy, which we termed the spin dive. Dives started with intense stroking and right-sided lateral rotation. This remarkable behaviour resulted in a rapid descent. By tracking the fine-scale foraging behaviour of seven tagged individuals, matched with prey layer recordings, we tested the hypothesis that spin dives are foraging dives targeting deep-dwelling prey. Hunting depth traced the diel movement of the deep scattering layer, a dense aggregation of prey, that resides deep during the day and near-surface at night. Individuals shifted their foraging strategy from deep spin dives to shallow non-spin dives around dusk. Spin dives were significantly faster, steeper and deeper than non-spin dives, effectively minimizing transit time to bountiful mesopelagic prey, and were focused on periods when the migratory prey might be easier to catch. Hence, whereas Risso's dolphins were mostly shallow, nocturnal foragers, their spin dives enabled extended and rewarding diurnal foraging on deep-dwelling prey.

scholarly journals How Gradient Affects the Foraging Decisions of Leaf Cutting Ants at the Food Source

2019 ◽  
Author(s):  
◽  
Sam Butler
Keyword(s):  
Foraging Behaviour ◽  
Feeding Site ◽  
Individual Level ◽  
Eusocial Insects ◽  
Methodological Errors ◽  
Foraging Decisions ◽  
Key Factor ◽  
Leaf Cutting ◽  
Load Size ◽  
Insight Into

The eusocial insects have long held the fascination of scientists for their co-operative behaviour, which can range from a small group of workers, to millions strong colonies, such as those found in the leaf cutting ant, Atta cephalotes. Though decades of research have allowed us some insight into their organisation and methods, there are many things that have gone unexplained. One of these is the mystery of why Atta consistently takes leaf loads back to the nest that are significantly smaller than would be optimal, when they should in theory optimise leaf transport rate. While compelling evidence has been presented to suggest that it is at least in part to do with how the leaves are processed inside the nest, here I present evidence to suggest that gradient is another key factor. This is a factor which has been explored only very cursorily up until now in leaf cutting ants, with experiments investigating it being extremely limited in scope, suffer from potential methodological errors or deal with grass cutting ants, which share many traits with leaf cutting ants, but have adapted to face different challenges. Upon a thorough examination of the effects of gradient, it was discovered that A. cephalotes favour a cautious, but more reliable method of transport. At almost every point, their behaviour shows the importance of maintaining grip on steep and vertical gradients to the point where it is prioritised over everything else, including speed and load size. While it may seem paradoxical to suggest that smaller loads, carried slower might result in a higher overall rate of leaf collection, a fast, but reckless approach might result in a high proportion of unsuccessful foraging trips, each of which costs energy and time. As a result, by increasing their success, rather than speed, they minimise wasted effort, loss of workers and potentially, have a higher rate of leaf collection over time. This aspect of leaf cutting ant behaviour shows that leaf cutting ants can change their priorities at the feeding site to best maximise transport success at an individual level, which demonstrates previously unappreciated plasticity and a new lens through which to view future investigations into ant foraging behaviour.

scholarly journals Be different to be better: the effect of personality on optimal foraging with incomplete knowledge

2021 ◽  
Author(s):  
Poppy M. Jeffries ◽  
Samantha C. Patrick ◽  
Jonathan R. Potts
Keyword(s):  
Optimal Foraging ◽  
Optimal Foraging Theory ◽  
Foraging Strategy ◽  
Foraging Strategies ◽  
Partial Knowledge ◽  
Marginal Value ◽  
Animal Populations ◽  
Plausible Mechanism ◽  
Insight Into ◽  
Modelling Approach

AbstractMany animal populations include a diversity of personalities, and these personalities are often linked to foraging strategy. However, it is not always clear why populations should evolve to have this diversity. Indeed, optimal foraging theory typically seeks out a single optimal strategy for individuals in a population. So why do we, in fact, see a variety of strategies existing in a single population? Here, we aim to provide insight into this conundrum by modelling the particular case of foraging seabirds, that forage on patchy prey. These seabirds have only partial knowledge of their environment: they do not know exactly where the next patch will emerge, but they may have some understanding of which locations are more likely to lead to patch emergence than others. Many existing optimal foraging studies assume either complete knowledge (e.g. Marginal Value Theorem) or no knowledge (e.g. Lévy Flight Hypothesis), but here we construct a new modelling approach which incorporates partial knowledge. In our model, different foraging strategies are favoured by different birds along the bold-shy personality continuum, so we can assess the optimality of a personality type. We show that it is optimal to be shy (resp. bold) when living in a population of bold (resp. shy) birds. This observation gives a plausible mechanism behind the emergence of diverse personalities. We also show that environmental degradation is likely to favour shyer birds and cause a decrease in diversity of personality over time.

scholarly journals Nonreciprocal charge transport up to room temperature in bulk Rashba semiconductor α-GeTe

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Yan Li ◽  
Yang Li ◽  
Peng Li ◽  
Bin Fang ◽  
Xu Yang ◽  
...  
Keyword(s):  
Charge Transport ◽  
Room Temperature ◽  
Theoretical Calculations ◽  
Ferromagnetic Layer ◽  
Spin Splitting ◽  
New Paradigm ◽  
Rashba Spin ◽  
Rashba Spin Splitting ◽  
Fundamental Insight ◽  
Insight Into

AbstractNonmagnetic Rashba systems with broken inversion symmetry are expected to exhibit nonreciprocal charge transport, a new paradigm of unidirectional magnetoresistance in the absence of ferromagnetic layer. So far, most work on nonreciprocal transport has been solely limited to cryogenic temperatures, which is a major obstacle for exploiting the room-temperature two-terminal devices based on such a nonreciprocal response. Here, we report a nonreciprocal charge transport behavior up to room temperature in semiconductor α-GeTe with coexisting the surface and bulk Rashba states. The combination of the band structure measurements and theoretical calculations strongly suggest that the nonreciprocal response is ascribed to the giant bulk Rashba spin splitting rather than the surface Rashba states. Remarkably, we find that the magnitude of the nonreciprocal response shows an unexpected non-monotonical dependence on temperature. The extended theoretical model based on the second-order spin–orbit coupled magnetotransport enables us to establish the correlation between the nonlinear magnetoresistance and the spin textures in the Rashba system. Our findings offer significant fundamental insight into the physics underlying the nonreciprocity and may pave a route for future rectification devices.

scholarly journals Temporal hierarchy of intrinsic neural timescales converges with spatial core-periphery organization

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Mehrshad Golesorkhi ◽  
Javier Gomez-Pilar ◽  
Shankar Tumati ◽  
Maia Fraser ◽  
Georg Northoff
Keyword(s):  
Time Window ◽  
Human Cortex ◽  
The Core ◽  
Novel Variant ◽  
Open Issue ◽  
Task Differences ◽  
Spatial Hierarchy ◽  
Fundamental Insight ◽  
Insight Into ◽  
And Task

AbstractThe human cortex exhibits intrinsic neural timescales that shape a temporal hierarchy. Whether this temporal hierarchy follows the spatial hierarchy of its topography, namely the core-periphery organization, remains an open issue. Using magnetoencephalography data, we investigate intrinsic neural timescales during rest and task states; we measure the autocorrelation window in short (ACW-50) and, introducing a novel variant, long (ACW-0) windows. We demonstrate longer ACW-50 and ACW-0 in networks located at the core compared to those at the periphery with rest and task states showing a high ACW correlation. Calculating rest-task differences, i.e., subtracting the shared core-periphery organization, reveals task-specific ACW changes in distinct networks. Finally, employing kernel density estimation, machine learning, and simulation, we demonstrate that ACW-0 exhibits better prediction in classifying a region’s time window as core or periphery. Overall, our findings provide fundamental insight into how the human cortex’s temporal hierarchy converges with its spatial core-periphery hierarchy.

scholarly journals Wind Energy Meteorology: Insight into Wind Properties in the Turbine-Rotor Layer of the Atmosphere from High-Resolution Doppler Lidar

2013 ◽  
Vol 94 (6) ◽  
pp. 883-902 ◽  
Author(s):  
Robert M. Banta ◽  
Yelena L. Pichugina ◽  
Neil D. Kelley ◽  
R. Michael Hardesty ◽  
W. Alan Brewer
Keyword(s):  
Wind Energy ◽  
Ground Level ◽  
Turbine Rotor ◽  
Energy Industry ◽  
Doppler Lidar ◽  
Near Surface ◽  
Surface Measurements ◽  
Wind Measurements ◽  
Upper Level ◽  
Insight Into

Addressing the need for high-quality wind information aloft in the layer occupied by turbine rotors (~30–150 m above ground level) is one of many significant challenges facing the wind energy industry. Without wind measurements at heights within the rotor sweep of the turbines, characteristics of the flow in this layer are unknown for wind energy and modeling purposes. Since flow in this layer is often decoupled from the surface, near-surface measurements are prone to errant extrapolation to these heights, and the behavior of the near-surface winds may not reflect that of the upper-level flow.

Evaporite Palynology: a case study on the Permian (Lopgingian) Zechstein Sea

2021 ◽  
pp. jgs2020-174
Author(s):  
Martha E. Gibson ◽  
David J. Bodman
Keyword(s):  
Thermal Conductivity ◽  
Heat Flux ◽  
Rapid Growth ◽  
Western Europe ◽  
Thermal Maturity ◽  
Near Surface ◽  
Wide Range ◽  
Terrestrial Environments ◽  
Insight Into

Evaporites characterize the Lopingian of Europe but present obstacles for biostratigraphic analysis. Here we present a case study for processing the Lopingian Zechstein Group evaporites of central-western Europe for the recovery of palynomorph assemblages. We demonstrate that full recovery is easily achieved with two main modes of palynomorph preservation observed; palynomorphs are either exceptionally well-preserved and orange-brown in colour, or poorly-preserved, brown-black, opaque and fragmented. The latter are reminiscent of palynomorphs of high thermal maturity. However, we propose that the intact nature of preservation is a result of the rapid growth of near-surface halite crystals, with their darkening a consequence of locally-enhanced heat flux due to the relatively high thermal conductivity of salt. This case study has enabled novel insight into an otherwise undescribed environment, and demonstrates the utility and possibility of extracting palynomorphs from a variety of rock salt types. This method should be applicable to a wide range of ancient evaporite and could also be applied to other Permian evaporite systems, which are used as analogues for extra-terrestrial environments.

scholarly journals Unearthing the Boreal Soil Resistome Associated with Permafrost Thaw

2020 ◽  
Author(s):  
Tracie J. Haan ◽  
Devin M. Drown
Keyword(s):  
Antibiotic Resistance ◽  
Active Layer ◽  
Resistance Genes ◽  
Soil Bacteria ◽  
Bacterial Community Composition ◽  
Ecological Niches ◽  
Whole Genome ◽  
Near Surface ◽  
Permafrost Thaw ◽  
Insight Into

ABSTRACTUnderstanding the distribution and mobility of antibiotic resistance genes (ARGs) in soil bacteria from diverse ecological niches is critical in assessing their impacts on the global spread of antibiotic resistance. In permafrost associated soils, climate and human driven forces augment near-surface thaw altering the overlying active layer. Physiochemical changes shift bacterial community composition and metabolic functioning, however, it is unknown if permafrost thaw will affect ARGs comprising the boreal soil resistome. To assess how thaw shifts the resistome, we performed susceptibility testing and whole genome sequencing on soil isolates from a disturbance-induced thaw gradient in Interior Alaska. We found resistance was widespread in the Alaskan isolates, with 87% of the 90 isolates resistant to at least one of the five antibiotics. We also observed positive trends in both the proportion of resistant isolates and the abundance of ARGs with permafrost thaw. However, the number of ARGs per genome and types of genes present were shown to cluster more strongly by bacterial taxa rather than thaw emphasizing the evolutionary origins of resistance and the role vertical gene transfer has in shaping the predominantly chromosomally encoded ARGs. The observed higher proportion of plasmid-borne and distinct ARGs in our isolates compared to RefSoil+ suggests local conditions affect the composition of the resistome along with selection for ARG mobility. Overall taxonomy and geography shape the resistome, suggesting that as microbial communities shift in response to permafrost thaw so will the ARGs in the boreal active layer.IMPORTANCEAs antibiotic resistance continues to emerge and rapidly spread in clinical settings, it is imperative to generate studies that build insight into the ecology of environmental resistance genes that pose a threat to human health. This study provides insight into the occurrence of diverse ARGs found in Alaskan soil bacteria which is suggestive of the potential to compromise health. The observed differences in ARG abundance with increasing permafrost thaw suggest the role of soil disturbance in driving the distribution of resistant determinants and the predominant taxa that shape the resistome. Moreover, the high-quality whole genome assemblies generated in this study are an extensive resource for microbial researchers interested in permafrost thaw and will provide a steppingstone for future research into ARG mobility and transmission risks.

scholarly journals Effect of ionic strength on shear-thinning nanoclay–polymer composite hydrogels

2018 ◽  
Vol 6 (8) ◽  
pp. 2073-2083 ◽  
Author(s):  
Amir Sheikhi ◽  
Samson Afewerki ◽  
Rahmi Oklu ◽  
Akhilesh K. Gaharwar ◽  
Ali Khademhosseini
Keyword(s):  
Ionic Strength ◽  
Rheological Properties ◽  
Polymer Composite ◽  
Biomedical Applications ◽  
Shear Thinning ◽  
Composite Hydrogels ◽  
Polymer Interactions ◽  
Fundamental Insight ◽  
Insight Into

The effect of ionic strength on the structure and rheological properties of nanoclay–gelatin shear-thinning biomaterials (STBs) is investigated. A fundamental insight into nanoclay–polymer interactions in physiological environments is provided to design clay-based biomaterials for biomedical applications.

scholarly journals Comparison of Molecular Recognition of Trimethyllysine and Trimethylthialysine by Epigenetic Reader Proteins

Molecules ◽  
2020 ◽  
Vol 25 (8) ◽  
pp. 1918 ◽  
Author(s):  
Jordi C. J. Hintzen ◽  
Jordi Poater ◽  
Kiran Kumar ◽  
Abbas H. K. Al Temimi ◽  
Bas J. G. E. Pieters ◽  
...  
Keyword(s):  
Molecular Recognition ◽  
Biomolecular Recognition ◽  
Crucial Importance ◽  
Binding Characteristics ◽  
Human Genes ◽  
Health And Disease ◽  
Fundamental Insight ◽  
Dynamics Simulations ◽  
Insight Into ◽  
Epigenetic Processes

Gaining a fundamental insight into the biomolecular recognition of posttranslationally modified histones by epigenetic reader proteins is of crucial importance to understanding the regulation of the activity of human genes. Here, we seek to establish whether trimethylthialysine, a simple trimethyllysine analogue generated through cysteine alkylation, is a good trimethyllysine mimic for studies on molecular recognition by reader proteins. Histone peptides bearing trimethylthialysine and trimethyllysine were examined for binding with five human reader proteins employing a combination of thermodynamic analyses, molecular dynamics simulations and quantum chemical analyses. Collectively, our experimental and computational findings reveal that trimethylthialysine and trimethyllysine exhibit very similar binding characteristics for the association with human reader proteins, thereby justifying the use of trimethylthialysine for studies aimed at dissecting the origin of biomolecular recognition in epigenetic processes that play important roles in human health and disease.

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