bluuebunny/crossref_metadata_2025_split huggingface dataset:
Computational homogenization based crystal plasticity investigation of deformation behavior of AA2024-T3 alloy at different strain rates
Authors: Singh Lakhwinder , Ha Sangyul , Vohra Sanjay , Sharma Manu 
Published: March 2023

PurposeModeling of material behavior by physically or microstructure-based models helps in understanding the relationships between its properties and microstructure. However, the majority of the numerical investigations on the prediction of the deformation behavior of AA2024 alloy are limited to the use of phenomenological or empirical constitutive models, which fail to take into account the actual microscopic-level mechanisms (i.e. crystallographic slip) causing plastic deformation. In order to achieve accurate predictions, the microstructure-based constitutive models involving the underlying physical deformation mechanisms are more reliable. Therefore, the aim of this work is to predict the mechanical response of AA2024-T3 alloy subjected to uniaxial tension at different strain rates, using a dislocation density-based crystal plasticity model in conjunction with computational homogenization.Design/methodology/approachA dislocation density-based crystal plasticity (CP) model along with computational homogenization is presented here for predicting the mechanical behavior of aluminium alloy AA2024-T3 under uniaxial tension at different strain rates. A representative volume element (RVE) containing 400 grains subjected to periodic boundary conditions has been used for simulations. The effect of mesh discretization on the mechanical response is investigated by considering different meshing resolutions for the RVE. Material parameters of the CP model have been calibrated by fitting the experimental data. Along with the CP model, Johnson–Cook (JC) model is also used for examining the stress-strain behavior of the alloy at various strain rates. Validation of the predictions of CP and JC models is done with the experimental results where the CP model has more accurately captured the deformation behavior of the aluminium alloy.FindingsThe CP model is able to predict the mechanical response of AA2024-T3 alloy over a wide range of strain rates with a single set of material parameters. Furthermore, it is observed that the inhomogeneity in stress-strain fields at the grain level is linked to both the orientation of the grains as well as their interactions with one another. The flow and hardening rule parameters influencing the stress-strain curve and capturing the strain rate dependency are also identified.Originality/valueComputational homogenization-based CP modeling and simulation of deformation behavior of polycrystalline alloy AA2024-T3 alloy at various strain rates is not available in the literature. Therefore, the present computational homogenization-based CP model can be used for predicting the deformation behavior of AA2024-T3 alloy more accurately at both micro and macro scales, under different strain rates.
Human cytomegalovirus infection activates NLRP3 inflammasome by releasing mtDNA into the cytosol in human THP‐1 cells
Authors: Xu Xi , Cai Junwen , Wang Xiaoming , Lu Yutian , Guo Binhan , Lai Meimei , Lan Linhua , Peng Ying , Zheng Xiaoqun 
Published: March 2023

AbstractHuman cytomegalovirus (HCMV) infection of monocytes results in the production of inflammatory cytokine through inflammasome. However, the mechanism of NLR family pyrin domain containing 3 (NLRP3) inflammasome activation in HCMV infection remains unclear. In this study, HCMV infection promoted the increase of mitochondrial fusion and caused mitochondrial dysfunction in THP‐1 cells, including excessive reactive oxygen species production and decreased mitochondrial membrane potential (Δψm). Meanwhile, the expression of mitochondrial DNA (mtDNA)‐binding protein TFAM (transcription factor A, mitochondrial) was decreased and mtDNA content in the cytoplasm was increased. Knockdown of TFAM caused an increase in mtDNA copy number in the cytoplasm and resulted in elevated NLRP3 expression, active caspase‐1, and mature IL‐1β. After a 3 h treatment with MCC950, an NLRP3 inhibitor, the increase of cleaved caspase‐1 and mature IL‐1β were suppressed. Besides, overexpression of TFAM inhibited the expression of NLRP3, cleaved caspase‐1, and mature IL‐1β. In addition, knockdown of NLRP3 inhibited the IL‐1β process after HCMV infection. mtDNA‐deficient cells showed a limited ability to produce NLRP3 and process IL‐1β after HCMV infection. In conclusion, HCMV infection of THP‐1 cells resulted in decreased mitochondrial TFAM protein expression and increased mtDNA release into the cytoplasm, which eventually led to the activation of NLRP3 inflammasome.
Sunflower spines and beyond: Mechanisms and breadth of pollen that reduce gut pathogen infection in the common eastern bumble bee
Authors: Figueroa Laura L. , Fowler Alison , Lopez Stephanie , Amaral Victoria E. , Koch Hauke , Stevenson Philip C. , Irwin Rebecca E. , Adler Lynn S. 
Published: March 2023

Abstract

Plants have unique chemical and physical traits that can reduce infections in animals ranging from primates to caterpillars. Sunflowers (Helianthus annuus; Asteraceae) are one striking example, with pollen that suppresses infections by the trypanosomatid gut pathogen Crithidia bombi in the common eastern bumble bee (Bombus impatiens). However, the mechanism underlying this effect has remained elusive, and we do not know whether pollens from other Asteraceae species have similar effects.

We evaluated whether mechanisms mediating sunflower pollen's antipathogenic effects are physical (due to its spiny exine), chemical (due to metabolites) or both. We also evaluated the degree to which pollen from seven other Asteraceae species reduced C. bombi infection relative to pollen from sunflower and two non‐Asteraceae species, and whether pollen spine length predicted pathogen suppression.

We found that sunflower exines alone reduced infection as effectively as whole sunflower pollen, while sunflower pollen metabolites did not. Furthermore, bees fed pollen from four of seven other Asteraceae had 62%–92% lower C. bombi infections than those fed non‐Asteraceae pollen. Spine length, however, did not explain variation in bumble bee infection.

Our study indicates that sunflower pollen's capacity to suppress C. bombi is driven by its spiny exine, and that this phenomenon extends to several other Asteraceae species. Our results indicate that sunflower pollen exines are as effective as whole pollen in reducing infection, suggesting that future studies should expand to assess the effects of other species with spiny pollen on pollinator–pathogen dynamics.

Read the free Plain Language Summary for this article on the Journal blog.
The costs and trade‐offs of optimal foraging in marine fish larvae
Authors: Hauss Helena , Schwabe Laura , Peck Myron A. 
Published: March 2023

Abstract

In a warming world, both the metabolic rates of ectotherm predators and the phenology of their prey organisms is subject to change. Knowledge on how intrinsic and extrinsic factors govern predator–prey interactions is essential in order to understand how the environment regulates the vital rates of consumers. Controlled experiments, however, simultaneously testing behavioural and growth responses of the larvae of fish and other ectotherm organisms in different feeding regimes are scarce.

Prey size (PS) selection was determined for young Atlantic herring Clupea harengus L. larvae offered 100‐ to 850‐μm copepods Acartia tonsa at five different concentrations. In separate, 4‐ (13°C) or 7‐day (7°C) trials, the effect of prey size on larval foraging behaviour, specific growth rate (SGR) and biochemical condition (RNA:DNA, RD, a proxy for individual instantaneous growth) was tested.

Preferred (selected) PS was similar at all prey concentrations but increased from 3% to 5% predator length with increasing larval size. At various temperatures, dome‐shaped relationships existed between PS and larval RD (and accordingly SGR). Compensatory changes in foraging behaviour (pause and feeding strike frequencies) existed but were not adequate to maintain positive SGR when available prey were substantially smaller than those preferred by larvae.

A physiology‐based model predicted that larvae depended more heavily on optimal prey sizes at the colder versus warmer temperature to grow well and that the profitable prey niche breadth (the range in prey sizes in which growth was positive) increased at warmer temperatures.

Seemingly subtle match‐mismatch dynamics between ectotherm predators and their preferred prey size can have large, temperature‐dependent consequences for rates of growth and likely survival of the predator. To the best knowledge, this was the first study to directly quantify the “costs and trade‐offs” of optimal foraging in marine fish larvae.
Poleward shifts and altered periodicity in boreal bird irruptions over six decades
Authors: Widick Ivy V. , Young Matthew A. , LaMontagne Jalene M. , Strong Courtenay , Zuckerberg Benjamin 
Published: March 2023

Abstract

Range boundaries are long‐term biogeographic features of species distributions and abundance. However, many species demonstrate dynamic range boundaries, reflecting strong seasonal and annual variability in migratory behaviour.

As a form of facultative migration, irruptions involve the movement of many individuals outside of their resident range in response to climate variability, resource availability, and demographic processes. Many species have experienced range shifts and altered phenology in response to modern climate change, but spatiotemporal changes in irruption dynamics are less well known.

We quantified changes in the geography and periodicity of boreal bird irruptions across eastern North America from 1960 to 2021. Using data from Audubon's Christmas Bird Count for nine finch species, including several exhibiting recent population declines, we evaluated latitudinal trends in southern range and irruption boundaries and characterized irruption periodicity using spectral wavelet analysis.

Six boreal birds exhibited significant northward shifts in their southern range boundaries and three species displayed shifts in their southern irruption boundaries.

Irruption periodicity across multiple species was consistent across the 1960s and 1970s, culminating in frequent and synchronized irruptions of multiple species (superflights) during earlier decades. Coherence between species dampened beginning in the early 1980s as superflight periodicity became increasingly unstructured, finally reforming in recent decades, after 2000.

Boreal birds are considered important sentinels of the boreal forests, and northward shifts and altered periodicity of irruptions may indicate broad‐scale changes in climate‐ and resource‐associated drivers operating across the boreal forests.
Variation in body size drives spatial and temporal variation in lobster–urchin interaction strength
Authors: DiFiore Bartholomew P. , Stier Adrian C. 
Published: March 2023

Abstract

How strongly predators and prey interact is both notoriously context dependent and difficult to measure. Yet across taxa, interaction strength is strongly related to predator size, prey size and prey density, suggesting that general cross‐taxonomic relationships could be used to predict how strongly individual species interact.

Here, we ask how accurately do general size‐scaling relationships predict variation in interaction strength between specific species that vary in size and density across space and time?

To address this question, we quantified the size and density dependence of the functional response of the California spiny lobster Panulirus interruptus, foraging on a key ecosystem engineer, the purple sea urchin Strongylocentrotus purpuratus, in experimental mesocosms. Based on these results, we then estimated variation in lobster–urchin interaction strength across five sites and 9 years of observational data. Finally, we compared our experimental estimates to predictions based on general size‐scaling relationships from the literature.

Our results reveal that predator and prey body size has the greatest effect on interaction strength when prey abundance is high. Due to consistently high urchin densities in the field, our simulations suggest that body size—relative to density—accounted for up to 87% of the spatio‐temporal variation in interaction strength. However, general size‐scaling relationships failed to predict the magnitude of interactions between lobster and urchin; even the best prediction from the literature was, on average, an order of magnitude (+18.7×) different than our experimental predictions.

Harvest and climate change are driving reductions in the average body size of many marine species. Anticipating how reductions in body size will alter species interactions is critical to managing marine systems in an ecosystem context. Our results highlight the extent to which differences in size‐frequency distributions can drive dramatic variation in the strength of interactions across narrow spatial and temporal scales. Furthermore, our work suggests that species‐specific estimates for the scaling of interaction strength with body size, rather than general size‐scaling relationships, are necessary to quantitatively predict how reductions in body size will alter interaction strengths.
Understanding community awareness of seagrass ecosystem services for their blue carbon conservation in marine protected areas: A case study of Karimunjawa National Park
Authors: Rifai Husen , Quevedo Jay Mar D. , Lukman Kevin M. , Hernawan Udhi Eko , Alifatri La‐ode , Risandi Johan , Kuswadi  , Kristiawan  , Uchiyama Yuta , Kohsaka Ryo 
Published: March 2023

AbstractSeagrasses provide diverse ecosystem services that support communities, yet, they are among the most threatened marine habitats. Efforts to conserve and sustainably manage seagrasses are increasing, particularly amidst the era of climate change, in which they play a critical role. However, these activities often received less attention or were slow in gaining momentum partly due to a lack of societal recognition of seagrasses and their importance. Thus, in this study, we collected community perceptions of seagrass ecosystem services and threats from 391 respondents in Karimunjawa National Park (KNP), a nationally declared protected area in Indonesia. We aim to provide insights on people's recognition of seagrasses from a local scale with strict protection measures. Overall, respondents showed varying perceptions of seagrass ecosystem services, with provisioning services more highly perceived than regulating services. The perceived level of threats was inconclusive, though, reclamation along shorelines received higher rates (leaning toward most damaging) than other threats such as natural disasters and illegal fishing activities. Sociodemographic attributes of respondents were found to influence their perceptions, with occupation as the most pronounced driving factor. The variations observed in seagrass perceptions suggest that there is a need to strengthen and/or enhance seagrass awareness and education campaigns, which is in line with the increasing demand that public perceptions matter for the conservation and sustainable management of seagrass ecosystems. We presented here the use and insights of community perceptions for seagrass blue carbon conservation in KNP, and consequently in Indonesia, where seagrass meadows are considered globally important carbon sinks.
Financial Reporting Quality and Wage Differentials: Evidence from Worker‐Level Data
Authors: CHOI JUNG HO , GIPPER BRANDON , MALIK SARA 
Published: March 2023

ABSTRACTWe examine whether financial reporting quality affects worker wages using employer‐employee matched data in the United States. We find that low financial reporting quality is associated with a compensating wage differential—that is, a risk premium—using three distinct approaches while controlling for worker characteristics by (1) regressing wages on firm‐year–level and firm‐level reporting quality, (2) documenting wage changes when workers switch firms, and (3) estimating a structural approach that separates reporting quality from performance‐related volatility. We find evidence consistent with two channels: performance pay and turnover risk, where workers bear risks from noise in performance measurement and unemployment, respectively. To mitigate endogeneity concerns, we show that—after the accounting scandals in 2002 and after the announcements of an internal control weakness (ICW)—former Arthur Andersen clients and ICW firms pay wage premiums to employees, with magnitudes between 0.9% and 2.8% of annual wages.
Context‐dependent insect predation pressure on an avian ectoparasite
Authors: Salido Angela , Veiga Jesús , Reyes‐López Joaquín Luis , Valera Francisco 
Published: March 2023

AbstractContext dependence arises when ecological relationships vary with the conditions under which they are observed. Context dependence of interactions involving parasites is poorly known, even if it is key to understanding host–parasite relationships and food web dynamics. This paper investigates to which extent predation pressure on an avian ectoparasite (Carnus hemapterus) is context‐dependent. Based on a predator‐exclusion experiment, predation pressure onC. hemapteruspupae in the host's nest for 3 years, and its variation between habitat types are quantified. Variation in precipitation and normalized difference vegetation index (NDVI) is also explored as a likely cause of context dependency. We hypothesize that predation pressure should fluctuate with such surrogates of food availability, so that inter‐annual and intra‐annual differences may emerge. The number of nests with significant reduction of pupae varied widely among years ranging from 24% to 75%. However, average pupae reduction in nests where a significant reduction occurred did not vary between years. No differences in predation rates between habitat types were detected. Precipitation and NDVI varied widely between years and NDVI was consistently lower around nests on cliffs than around nests on trees and farmhouses. Parallels were found between variation in predation pressure and precipitation/NDVI at a wide scale (highest predation the driest year, and much lower the 2 rainier ones), but not at the nest scale. This paper shows clear context‐dependent insect predation pressure on an ectoparasite under natural conditions, and that such interaction changes in signs rather than magnitude between years. The causes for these variations require longer‐term studies and/or well‐designed, large‐scale experiments.
Chromosome‐level de novo genome assembly of two conifer‐parasitic wasps, Megastigmus duclouxiana and Megastigmus sabinae, reveals genomic imprints of adaptation to hosts
Authors: Kuang Jing‐Ge , Han Zhi‐Tong , Kang Ming‐Hui , Ju Tsam , Tso Sonam , Chen Xiao‐Xiao , Li Jia‐Liang , Xiong Zhong‐Ping , Ma Tao , Mao Kang‐Shan 
Published: March 2023

AbstractConifers make up about one third of global forests but are threatened by seed parasitoid wasp species. Many of these wasps belong to the genus Megastigmus, yet little is known about their genomic background. In this study, we provide chromosome‐level genome assemblies for two oligophagous conifer parasitoid species of Megastigmus, which represent the first two chromosome‐level genomes of the genus. The assembled genomes of Megastigmus duclouxiana and M. sabinae are 878.48 Mb (scaffold N50 of 215.60 Mb) and 812.98 Mb (scaffold N50 of 139.16 Mb), respectively, which are larger than the genome size of most hymenopterans due to the expansion of transposable elements. Expanded gene families highlight the difference in sensory‐related genes between the two species, reflecting the difference in their hosts. We further found that these two species have fewer family members but more single‐gene duplications than polyphagous congeners in the gene families of ATP‐binding cassette transporter (ABC), cytochrome P450 (P450) and olfactory receptors (OR). These findings shed light on the pattern of adaptation to a narrow spectrum of hosts in oligophagous parasitoids. Our findings suggest potential drivers underlying genome evolution and parasitism adaptation, and provide valuable resources for understanding the ecology, genetics and evolution of Megastigmus, as well as for the research and biological control of global conifer forest pests.
The importance of feeding fast when thieves are around: A case study on Whimbrels foraging on a wave‐exposed sandy beach in southern Chile
Authors: Morales‐Torres Diego F. , Valdivia Nelson , Rodríguez Sara M. , Navedo Juan G. 
Published: March 2023

AbstractPrey profitability is one of the most important factors influencing prey selection. This factor varies along with both prey size and handling time. Thus, large prey are generally highly profitable for consumers and boost competition. Kleptoparasitism is a form of competition in which an individual steals food previously obtained by another individual. Accordingly, handling large prey should increase the likelihood of kleptoparasitism occurrence, but these relationships remain poorly understood. Here, we studied kleptoparasitism occurrence by the Brown‐Hooded Gull (Chroicocephalus maculipennis – Laridae) on Whimbrels (Numenius phaeopus hudsonicus – Scolopacidae) preying on intertidal Mole Crabs (Emerita analoga) in a wave‐exposed sandy beach in southern Chile. Generalized linear models, fitted to data from focal‐individual video sequences, showed that kleptoparasitism probability had a positive sigmoidal response to handling time. Moreover, with an increase of 1 s in handling time, a Whimbrel doubled its probability of being kleptoparasitized. Additionally, the odds of being kleptoparasitized were 17% higher with an increase of 10 mm in prey length and 47% higher with an increase of one gull per host. However, the effect of handling on kleptoparasitism probability slightly decreased (2%) with an increase of 10 mm in prey size class. Our results suggest the existence of a threshold time in which consumers can handle their prey before kleptoparasitism probability is too high. Nevertheless, Whimbrel's mean intake rate reached 0.15 ± 0.13 kJ s−1, allowing Whimbrels to theoretically meet their energetic requirements despite losing some prey to kleptoparasites. This study provides new insight into a common form of competition among consumers, highlighting the importance of prey handling time for shorebirds with a restricted foraging time driven by tidal cycles.