Large Size Range Research Articles

Large range sizes link fast life histories with high species richness across wet tropical tree floras

Understanding how the traits of lineages are related to diversification is key for elucidating the origin of variation in species richness. Here, we test whether traits are related to species richness among lineages of trees from all major biogeographical settings of the lowland wet tropics. We explore whether variation in mortality rate, breeding system and maximum diameter are related to species richness, either directly or via associations with range size, among 463 genera that contain wet tropical forest trees. For Amazonian genera, we also explore whether traits are related to species richness via variation among genera in mean species-level range size. Lineages with higher mortality rates—faster life-history strategies—have larger ranges in all biogeographic settings and have higher mean species-level range sizes in Amazonia. These lineages also have smaller maximum diameters and, in the Americas, contain dioecious species. In turn, lineages with greater overall range size have higher species richness. Our results show that fast life-history strategies influence species richness in all biogeographic settings because lineages with these ecological strategies have greater range sizes. These links suggest that dispersal has been a key process in the evolution of the tropical forest flora.

Characterizing heterogeneities in the subsurface with an ultra-wideband GPR: Application to WISDOM, the GPR of the Rosalind Franklin ExoMars mission

Ultra-wideband Ground Penetrating Radars (GPR) are sensitive to a large range of scatterer sizes. Considering fractal heterogeneities in the subsurface, we propose a method to retrieve their typical size L. The determination of L with this method does not require a priori knowledge of the statistical distribution of permittivity values in the investigated subsurface. The method relies on the analysis of the backscattered signal by frequency/wavelength sub-bands. It is adapted to WISDOM, the GPR onboard the rover of the Rosalind Franklin ExoMars mission (ESA), but can be applied to any ultra-wideband GPR. Based on numerical simulations, a maximum in volume backscattering is reached at the wavelength (in the subsurface) . We demonstrate that this maximum, and therefore L, can be identified even in presence of moderate electrical losses, compatible with conditions expected on the Moon or Mars. Assuming an average permittivity of 5, WISDOM (0.5-3 GHz) data products could be used to estimate L as long as it is in the range 0.9-4.2 cm The retrieval method for L is validated on experimental WISDOM data acquired in a controlled environment.

Influence of ecological characteristics and phylogeny on native plant species' commercial availability.

Plant vendors generate a commercial species pool, the subset of species in a regional flora that is purchasable. The availability of plant species from commercial vendors can influence the composition and outcomes of conservation, landscaping, and restoration plantings. Although previous research suggests that most plant species are unavailable, there is little information that identifies the plant characteristics associated with commercial availability. We studied the composition of the commercial species pool by examining the ecology, phylogeny, and phenology of a regional flora in the Midwestern United States. We used a database of native plant species sold by 557 vendors throughout the Midwest (USA) to characterize species' availability. We compiled ecological characteristics of all plant species, including range size, growth form, moisture requirements, and conservatism-meaning fidelity to high-quality natural areas. We characterized phenological (bloom time) data for a subset of the regional flora. Finally, we constructed a regional phylogeny to assess the phylogenetic signal of plant availability. We expected that commercially unavailable species would be niche specialists or short-lived (often nonconservative "weedy") species, and that they would bloom earlier in the season and for a shorter time. We found that commercially available species were more long-lived, had larger range sizes, had intermediate fidelities to wetlands and high-quality or disturbed natural areas, and were associated with certain plant types, especially shrubs and trees. In contrast, ferns and graminoids were underrepresented in the commercial trade. There was a strong phylogenetic signal associated with commercial availability; some plant families had nearly all or none of their species commercially available. Example families with low representation included Orchidaceae, Potamogetonaceae, Cyperaceae, and fern families. Longer bloomed species were more commercially available, but we did not find differences in availability between early- and late-blooming species. Despite the diversity of the commercial pool in the Midwest, it is an unrepresentative, nonrandom subset of the regional species pool. This finding may promote the mismatch in species diversity and composition between remnant natural habitats and restorations because many specialized species are commercially unavailable to conservation and restoration practitioners. We encourage strategies to promote the availability of underrepresented plant diversity in the commercial species pool.

Adan: Adaptive Nesterov Momentum Algorithm for Faster Optimizing Deep Models.

In deep learning, different kinds of deep networks typically need different optimizers, which have to be chosen after multiple trials, making the training process inefficient. To relieve this issue and consistently improve the model training speed across deep networks, we propose the ADAptive Nesterov momentum algorithm, Adan for short. Adan first reformulates the vanilla Nesterov acceleration to develop a new Nesterov momentum estimation (NME) method, which avoids the extra overhead of computing gradient at the extrapolation point. Then Adan adopts NME to estimate the gradient's first- and second-order moments in adaptive gradient algorithms for convergence acceleration. Besides, we prove that Adan finds an ϵ-approximate first-order stationary point within O(ϵ-3.5) stochastic gradient complexity on the non-convex stochastic problems (e.g., deep learning problems), matching the best-known lower bound. Extensive experimental results show that Adan consistently surpasses the corresponding SoTA optimizers on vision, language, and RL tasks and sets new SoTAs for many popular networks and frameworks, e.g., ResNet, ConvNext, ViT, Swin, MAE, DETR, GPT-2, Transformer-XL, and BERT. More surprisingly, Adan can use half of the training cost (epochs) of SoTA optimizers to achieve higher or comparable performance on ViT, GPT-2, MAE, etc, and also shows great tolerance to a large range of minibatch size, e.g., from 1 k to 32 k.

The synergistic effect of micro/nanostructure length scale and fluid thermophysical properties on pool boiling heat transfer

Facile surface micro/nanostructuring techniques for additively-manufactured (AM) aluminum alloy (AlSi10Mg) have recently been developed. The structuring techniques are not only highly scalable, but they also enable the tailoring of structure length scale and morphology to enhance pool boiling heat transfer coefficient. Our past study revealed that the structure cavity size of 5 µm is favorable for bubble nucleation during pool boiling of dielectric fluid, HFE-7100, resulting in significant enhancements in the heat transfer coefficients (h). However, owing to the differences in thermophysical properties between different coolant fluids, including saturation temperature, latent heat of vaporization and surface tension, the required structure size range for bubble nucleation and capillary wicking force for liquid re-supply are expected to differ significantly. To explore the effect of structure length scale on the pool boiling performance of coolants with different thermophysical properties, this work develops a new surface structuring technique consisting of a dual-stage metallurgic heat treatment process and single-stage crystallographic etching process to tune the structure length scale across nearly two orders of magnitude, viz., from 0.3 to 15 μm. Using coolant media of vastly different thermophysical properties, i.e., dielectric fluid HFE-7100 and deionized water, we show that while microcavities with sizes ranging from 3 to 8 μm are favorable bubble nucleation sites for boiling of HFE-7100, which result in the enhancement of the maximum heat transfer coefficient (hmax) by 83.4 to 103.8 % as compared to a conventional plain Al6061 surface, larger microcavity sizes of 10 to 15 μm are required to effectively promote bubble nucleation of water. This large microcavity size range of 10 to 15 μm, produced through rational nanoparticle agglomeration of the rich Si-phase in AM AlSi10Mg in elevated temperature, followed by an indirect removal process using a chemical process, is found to significantly increase hmax of water by up to 259.9 % as compared to conventional nanostructures formed on Al6061. In addition, the new AM structured surfaces also exhibit up to 26.6 % enhancement in critical heat flux (CHF) as compared to highly-wicking conventional nanostructured Al6061. In summary, by utilizing scalable fabrication techniques to tailor the structure length scale on AM AlSi10Mg, this work not only reveals the favorable microcavity sizes for bubble nucleation of different coolant fluids to enhance boiling, but it also provides useful micro/nanostructure design guidelines that can be adopted to enhance boiling of other coolants and phase change applications.

Investigating the Biotic and Abiotic Drivers of Body Size Disparity in Communities of Non‐Volant Terrestrial Mammals

ABSTRACTAimThe species that compose local communities possess unique sets of functional and ecological traits that can be used as indicators of biotic and abiotic variation across space and time. Body size is a particularly relevant trait because species with different body sizes typically have different life history strategies and occupy distinct niches. Here we used the body sizes of non‐volant (i.e., non‐flying) terrestrial mammals to quantify and compare the body size disparity of mammal communities across the globe.LocationGlobal.Time PeriodPresent.Major Taxa StudiedNon‐volant terrestrial mammals.MethodsWe used IUCN range maps of 3982 terrestrial mammals to identify 1876 communities. We then combined diet data with data on climate, elevation and anthropogenic pressures to evaluate these variables' relative importance on the observed body size dispersion of these communities and its deviation from a null model.ResultsDispersion for these communities is significantly greater than expected in 54% of communities and significantly less than expected in 30% of communities. The number of very large species, continent, range sizes, diet disparity and annual temperature collectively explain > 50% of the variation in observed dispersion, whereas continent, the number of very large species, and precipitation collectively explain > 30% of the deviation from the null model.Main ConclusionsClimate and elevation have minimal predictive power, suggesting that biotic factors may be more important for explaining community body size distributions. However, continent is consistently a strong predictor of dispersion, likely due to it capturing the combined effects of climate, size‐selective human‐induced extinctions and more. Overall, our results are consistent with several plausible explanations, including, but not limited to, competitive exclusion, unequal distribution of resources, within‐community environmental heterogeneity, habitat filtering and ecosystem engineering. Further work focusing on other confounding variables, at finer spatial scales and/or within more causal frameworks is required to better understand the driver(s) of these patterns.

Spatial pattern and ecological adaptation of heterostylous and homostylous species of Primula in China

Abstract Floral syndrome is one of the key components of plant pollination syndromes, affecting variety of evolutionary and ecological processes in angiosperms. The evolutionary transition from self-incompatible heterostyly to self-compatible homostyly occurred repeatedly in angiosperm families. Although the evolution of heterostyly and homostyly has been deeply studied, our understanding on their differences in ecological strategies is still lacking. In this work, using the floral syndrome and distributions of the Primula in China we compared the spatial pattern of floral syndrome frequency and its climatic determinants. Our results reveal that distylous and homostylous Primula have similar primary centers of species diversity in southwest China, while distylous species have larger range size than homostylous ones. Temperature seasonality is the dominant climate factor of these geographic patterns, but its effect is much stronger in distylous than in homostylous Primula. Distylous species have larger flower size and number, and fruit size than homostylous ones. Climate, especially temperature seasonality mainly influenced species range size via its effects on floral syndrome. Our study suggests that homostyly is likely derived from heterostylous ancestors in similar geographical context, and larger reproductive investment in floral phenotype may provide compensatory mechanisms for obligate out-breeding heterostyly. Future investigations regarding the evolutionary history and tolerance or resistance to environmental change between distyly and homostyly may greatly advance our understanding of their spatial pattern and adaptative differences.

Jovian Vortex Hunter: A Citizen Science Project to Study Jupiter’s Vortices

The Jovian atmosphere contains a wide diversity of vortices, which have a large range of sizes, colors, and forms in different dynamical regimes. The formation processes for these vortices are poorly understood, and aside from a few known, long-lived ovals, such as the Great Red Spot and Oval BA, vortex stability and their temporal evolution are currently largely unknown. In this study, we use JunoCam data and a citizen science project on Zooniverse to derive a catalog of vortices, some with repeated observations, from 2018 May to 2021 September, and we analyze their associated properties, such as size, location, and color. We find that different-colored vortices (binned as white, red, brown, and dark) follow vastly different distributions in terms of their sizes and where they are found on the planet. We employ a simplified stability criterion using these vortices as a proxy, to derive a minimum Rossby deformation length for the planet of ∼1800 km. We find that this value of L d is largely constant throughout the atmosphere and does not have an appreciable meridional gradient.

Impact of various aggregation kinetics on thermophoretic velocity of asphaltene deposition.

Asphaltene deposition may pose serious challenges to flow assurance of crude oil in well columns. Different aggregation kinetics would partly be responsible for asphaltene particle growth ending in deposition on the surface of well columns. This work primarily investigates the thermophoretic deposition velocity caused by temperature gradients inside well columns for various asphaltene aggregation kinetics, including crossover behaviour, sedimentation, reaction-limited aggregation (RLA), and diffusion-limited aggregation (DLA). To do so, the experimental observations of size distribution for a live crude oil was performed at 80°C and pressure range of 4500-5500 psia. Moreover, various patterns of different size distributions were gathered from the literature for the sake of comparison. Next, a well column in southern Iran was selected to study the kinetic behaviour of thermophoretic velocity of deposition, with a difference between geothermal and static temperatures of around 5 to 50°C. The non-isothermal deposition velocity was shown to decrease from the top to the bottom of the well column, according to the findings of the study. The results also revealed that the thermophoretic velocity decreases as particle size increases and vice versa. This was confirmed by examining a comparably large range of asphaltene particle sizes, ranging from approximately 100 nm to roughly 9 µm. Practical implications of these findings were also discussed which would provide guidance for mitigation of asphaltene deposition in well columns.

Western spotted skunk spatial ecology in the temperate rainforests of the Pacific Northwest

AbstractA major threat to small mammalian carnivore populations is human‐induced land use change, but conservation and management are inhibited by limited knowledge about their ecology and natural history. To fill a key knowledge gap of the western spotted skunk (Spilogale gracilis), we investigated their spatial ecology at the landscape and home range scale in the temperate rainforests of the Oregon Cascades during 2017–2019. For the landscape scale analysis, we used detections of western spotted skunks at 112 baited camera traps and fitted a dynamic occupancy model to investigate spatial distribution and drivers of inter‐seasonal and inter‐annual changes in occupancy. Concurrently, we radio‐collared 25 spotted skunks (9 female, 16 male) and collected 1583 relocations. Using continuous‐time movement models, we estimated large home range sizes for both male and female spotted skunks, relative to their body mass, and highly overlapping home ranges that indicated a lack of territoriality. Using these home ranges, we fitted a resource selection function using environmental covariates that we assigned to various hypotheses such as resources, predator avoidance, thermal tolerance, and disturbance. Overall, western spotted skunks were widely distributed across our study area (seasonal occupancy up to 63.7 ± 5.3%) and highly detectable (weekly detection probability = 41.2%). At both spatial scales, spotted skunks selected wetter areas and local valleys, which we attributed to areas with more food resources. At the home range scale, spotted skunks selected locations with lower predation risk and areas surrounded by more previously logged forests. In this montane environment, inter‐seasonal contractions in the spatial distributions of spotted skunks were strongly driven by their response to cold temperature and accumulated snow. This was especially evident when seasonal occupancy declined significantly following a severe heavy snow event in February 2019. Given that there is little information available on the natural history of the western spotted skunk, these results provide essential information about their ecology to focus future monitoring efforts and may help identify potential threats (e.g., forest management, severe snow events, or wildfires) to this species.

Multigenerational toxicity of microplastics derived from two types of agricultural mulching films to Folsomia candida

Degradation and fragmentation of mulching films represents an increasing source of microplastics (MPs, plastic particles 1 μm to 5 mm in size) to agricultural soils. MPs have been shown to affect many soil invertebrates, including springtails. However, these studies typically use test materials representing less environmentally relevant particle types, such as pristine uniform MPs, which do not represent the large range of particle sizes and morphologies found in the field. This study aimed at providing insight into the adverse effects of MPs originating from agricultural mulching films, by using artificially aged MPs derived from both biodegradable (starch-polybutadiene adipate terephthalate (PBAT)) blend, as well as conventional (linear low-density polyethylene (LLDPE)) plastic polymers. The soil dwelling springtail Folsomia candida was exposed to these MPs for five generations in order to elucidate population effects due to possible reproduction toxicity, endocrine disruption, mutagenesis or developmental toxicity. F. candida were exposed to 0, 0.0016, 0.008, 0.04, 0.2, 1, 2, 3, 4 and 5 % (w/w dry soil) MPs in Lufa 2.2 soil, which includes concentrations within the range of environmental relevance. Juveniles produced at each concentration were transferred to the next generation, with the parental, F2 and F4 generations being exposed for four weeks and F1 and F3 generations for five weeks. No concentration-dependent effects on F. candida survival or reproduction were observed in exposures to either of the MPs, in any of the generations. These results suggest that the particular MPs used in this study, derived from mulching films used on agricultural soils, may not be potent toxicants to F. candida, even after long-term exposure and at elevated concentrations.

Mechanical strategies supporting growth and size diversity in Filamentous Fungi.

The stereotypical tip growth of filamentous fungi supports their lifestyles and functions. It relies on the polarized remodeling and expansion of a protective elastic cell wall (CW) driven by large cytoplasmic turgor pressure. Remarkably, hyphal filament diameters and cell elongation rates can vary extensively among different fungi. To date, however, how fungal cell mechanics may be adapted to support these morphological diversities while ensuring surface integrity remains unknown. Here, we combined super-resolution imaging and deflation assays to measure local CW thickness, elasticity and turgor in a set of fungal species spread on the evolutionary tree that spans a large range in cell size and growth speeds. While CW elasticity exhibited dispersed values, presumably reflecting differences in CW composition, both thickness and turgor scaled in dose-dependence with cell diameter and growth speeds. Notably, larger cells exhibited thinner lateral CWs, and faster cells thinner apical CWs. Counterintuitively, turgor pressure was also inversely scaled with cell diameter and tip growth speed, challenging the idea that turgor is the primary factor dictating tip elongation rates. We propose that fast-growing cells with rapid CW turnover have evolved strategies based on a less turgid cytoplasm and thin walls to safeguard surface integrity and survival.

Flotation Coefficient Distributions of Lipid Nanoparticles by Sedimentation Velocity Analytical Ultracentrifugation.

The robust characterization of lipid nanoparticles (LNPs) encapsulating therapeutics or vaccines is an important and multifaceted translational problem. Sedimentation velocity analytical ultracentrifugation (SV-AUC) has proven to be a powerful approach in the characterization of size-distribution, interactions, and composition of various types of nanoparticles across a large size range, including metal nanoparticles (NPs), polymeric NPs, and also nucleic acid loaded viral capsids. Similar potential of SV-AUC can be expected for the characterization of LNPs, but is hindered by the flotation of LNPs being incompatible with common sedimentation analysis models. To address this gap, we developed a high-resolution, diffusion-deconvoluted sedimentation/flotation distribution analysis approach analogous to the most widely used sedimentation analysis model c(s). The approach takes advantage of independent measurements of the average particle size or diffusion coefficient, which can be conveniently determined, for example, by dynamic light scattering (DLS). We demonstrate the application to an experimental model of extruded liposomes as well as a commercial LNP product and discuss experimental potential and limitations of SV-AUC. The method is implemented analogously to the sedimentation models in the free, widely used SEDFIT software.

A 2-year intercomparison of three methods for measuring black carbon concentration at a high-altitude research station in Europe

Abstract. Black carbon (BC) is one of the most important climate forcers with severe health effects. Large uncertainties in radiative forcing estimation and health impact assessment arise from the fact that there is no standardized method to measure BC mass concentration. This study presents a 2-year comparison of three state-of-the-art BC measurement techniques at the high-altitude research station Pic du Midi (PDM) located in the French Pyrenees at an altitude of 2877 m above sea level. A recently upgraded Aethalometer AE33, a thermal-optical analyser Sunset and a single-particle soot photometer SP2 were deployed to measure simultaneously the mass concentration of equivalent black carbon (MeBC), elemental carbon (MEC) and refractory black carbon (MrBC), respectively. Significant deviations in the response of the instruments were observed. All techniques responded to seasonal variations in the atmospheric changes in BC levels and exhibited good correlation during the whole study period. This indicates that the different instruments quantified the same particle type despite the fact that they are based on different physical principles. However the slopes and correlation coefficients varied between instrument pairs. The largest biases were observed for the AE33 with MeBC values that were around 2 times greater than MrBC and MEC values. The principal reasons of such large discrepancy were explained by the mass absorption cross section (MAC) that was too low and C values recommended by the AE33 manufacturer and applied to the absorption coefficients measured by the AE33. In addition, the long-range transport of dust particles at PDM in spring caused significant increases in the bias between AE33 and SP2 by up to a factor 8. The Sunset MEC measurements agreed within around 17 % with the SP2 MrBC values. The largest overestimations of MEC were observed when the total carbon concentrations were below 25 µg C cm−2, which is probably linked to the incorrect determination of the organic carbon (OC)–EC split point. Another cause of the discrepancy between instruments was found to be the limited detection range of the SP2, which did not allow for the total detection of fine rBC particles. The procedure used to estimate the missing mass fraction of rBC not covered by the measurement range of the SP2 was found to be critical. We found that a time-dependent correction based on fitting the observed rBC size distribution with a multimodal lognormal distribution is needed to accurately estimate MrBC over a larger size range.

Reconciling Coulter Counter and laser diffraction particle size analysis for aquaculture monitoring

The disaggregated inorganic grain size (DIGS) of bottom sediment analyzed with a Coulter Counter (CC) has been used to show that the fraction of sediment deposited in flocs (floc fraction) increased in both the near and far field after the introduction of open cage salmon aquaculture, altering benthic habitat and species composition. As a result, DIGS was identified as a potential indicator of regional environmental changes due to aquaculture. Laser diffraction is an attractive alternative to the CC because of its greater efficiency and larger size range. To determine if a laser diffraction instrument, Beckman-Coulter LS 13 320 (LS), could replace the CC within a Canadian national aquaculture monitoring program, the DIGS of 581 samples from five different regions in eastern Canada were analyzed with an LS and a CC. Results show that the LS could not be used to calculate floc fraction. Instead, % sortable silt and the volume % of inorganic particles < 16 µm were evaluated as alternative proxies for fine sediment properties. LS and CC values for these parameters were correlated, but they were significantly different and the relationship between the instruments was dependent on the area sampled. The LS did not capture variations between areas seen in the CC DIGS data. Where the DIGS from the CC found no sorting in the finest size classes, all the LS samples had similar size distributions characterized by smooth modal peaks. The LS and CC both return values that can be used to monitor changes in the deposition of fine-grained sediment, but the LS cannot determine changes in floc deposition and caution is required if comparing different sedimentary environments.

Drift drives the evolution of chromosome number II: The impact of range size on genome evolution in Carnivora.

Chromosome number is a fundamental genomic trait that is often the first recorded characteristic of a genome. Across large clades, a common pattern emerges: many or even most lineages exhibit relative stasis, while a handful of lineages or species exhibit striking variation. Despite recent developments in comparative methods, most of this heterogeneity is still poorly understood. It is essential to understand why some lineages have rapid rates of chromosome number evolution, as it can impact a variety of other traits. Previous research suggests that biased female meiotic drive may shape rates of karyotype evolution in some mammals. However, Carnivora exhibits variation that this female meiotic drive model cannot explain. We hypothesize that variation in effective population size may underlie rate variation in Carnivora. To test this hypothesis, we estimated rates of fusions and fissions while accounting for range size, which we use as a proxy for effective population size. We reason fusions and fissions are deleterious or underdominant and that only in lineages with small range sizes will these changes be able to fix due to genetic drift. In this study, we find that the rates of fusions and fissions are elevated in taxa with small range sizes relative to those with large range sizes. Based on these findings, we conclude that 1) naturally occurring structural mutations that change chromosome number are underdominant or mildly deleterious, and 2) when population sizes are small, structural rearrangements may play an important role in speciation and reduction in gene flow among populations.

Skeletal muscle preservation in arctic ground squirrels during hibernation season

Reduced skeletal loading leads to muscle atrophy in humans and most mammals. By contrast, hibernating mammals demonstrate limited loss of skeletal muscle mass and strength by the end of winter after being physically inactive for several months. The present study objective was to establish potential underlying processes for the lack of muscle loss during the hibernation season of arctic ground squirrels (AGS). Our hypothesis was that early in the the hibernation season, protective mechanisms of AGS are not yet mobilized and muscles show signs of atrophy, while compensatory processes for preventing muscle loss appear at a later time point. Quadriceps muscles of juvenile male AGS were collected shortly before hibernation, and on 2, 6, 10-12 and 16-22 weeks during hibernation. Pre-hibernating animals were used as controls. Fiber cross-sectional area (CSA) and fiber type composition were determined with immunohistochemistry. Amount of total RNA, ribosomal RNA content and expression levels of genes involved in 2 pathways of protein degradation, ubiquitination and autophagy, were analyzed by real-time PCR, to evaluate molecular mechanisms of muscle maintenance. One-Way ANOVA was used to statistically analyze the group differences. We found that CSA was not different between the groups (P &gt; 0.05). CSA frequency distribution curves did not reveal any shift to a smaller or larger size range. No difference was detected in myofiber composition between the hibernation groups compared to the control. Total RNA and ribosomal RNA content were not significantly different between the groups during hibernation. Muscle atrophy marker FBXO32 (Atrogin-1, MAFBX) and autophagy related genes MAP1LC3A and BECN1 did not show different level of expression between the groups. Only another muscle atrophy marker TRIM63 (MURF-1, Iris Ring Finger Protein) was significantly over-expressed at the time point of 2 weeks of hibernation. These results indicate that throughout the hibernation season, AGS preserve muscle fiber CSA showing limited signs of muscle atrophy only during the first weeks of hibernation, and yet-to-be determined processes exist to suppress protein degradation in AGS muscles during hibernation. The work was supported by Center of Biomedical Research Excellence under grant number [P20GM130443]. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Potential of powder metallurgical methods to fabricate Fe-6.5Si soft magnetic components

The soft magnetic Fe-6.5Si alloy is well known for its excellent soft magnetic properties but its usage is limited due to fabricational constrains by conventional methods. Powder metallurgical processing of Fe-6.5Si is possible by a variety of different methods shown here, sinter-based screen printing (SP), electron beam powder bed fusion (E-PBF) and field-assisted sintering (field-assisted sintering/spark plasma sintering, FAST/SPS). The microstructure of the components varies strongly by process and powder used which is directly influencing their soft magnetic properties. The correlation between powder properties and processing parameters on the structural and magnetic properties is established. Lowest coercivity ( H c = 7 A m−1) is achieved by E-PBF due to large grain size minimising hysteresis losses necessary for direct current applications. SP can provide sheets with low coercivity ( H c = 21 A m−1) and adjustable thickness reducing eddy current losses especially suitable for alternating current application at higher frequencies. FAST/SPS can be used for a large range of powder particle sizes which is suitable to tune the soft magnetic properties in a wide range between 40 and 210 A m−1.

Relative Humidity-Dependent Phase Transitions in Submicron Respiratory Aerosols.

Respiratory viruses, such as influenza and severe acute respiratory syndrome coronavirus 2, represent a substantial public health burden and are largely transmitted through respiratory droplets and aerosols. Environmental factors such as relative humidity (RH) and temperature impact virus transmission rates, and a precise mechanistic understanding of the connection between these environmental factors and virus transmission would improve efforts to mitigate respiratory disease transmission. Previous studies on supermicrometer particles observed RH-dependent phase transitions and linked particle phase state to virus viability. Phase transitions in atmospheric aerosols are dependent on size in the submicrometer range, and actual respiratory particles are expelled over a large size range, including submicrometer aerosols that can transmit diseases over long distances. Here, we directly investigated the phase transitions of submicrometer model respiratory aerosols. A probe molecule, Nile red, was added to particle systems including multiple mucin/salt mixtures, a growth medium, and simulated lung fluid. For each system, the polarity-dependent fluorescence emission was measured following RH conditioning. Notably, the fluorescence measurements of mucin/NaCl and Dulbecco's modified Eagle's medium particles indicated that liquid-liquid phase separation (LLPS) also occurs in submicron particles, suggesting that LLPS can also impact the viability of viruses in submicron particles and thus affect aerosol virus transmission. Furthermore, the utility of fluorescence-based measurements to study submicrometer respiratory particle physicochemical properties in situ is demonstrated.

Do aposematic species have larger range sizes? A case study with neotropical poison frogs

AbstractAimAposematic animals, i.e., those that are defended and warn potential predators through signals, are suggested to have resource‐gathering advantages against non‐aposematic ones. We here explore this in a biogeographic framework expecting that aposematic species are better dispersers, which translates into larger geographic range size.LocationSouth America.TaxonPoison frogs (Amphibia; Aromobatidae and Dendrobatidae).MethodsWe use 43 toxic and 26 non‐toxic poison frog species from the lowlands only as representatives of aposematic and non‐aposematic study organisms, respectively. Realised and potential geographic ranges are calculated using minimum convex polygon and species distribution modelling methods, respectively. Accounting for species body size and phylogeny, we test if both range and aposematism are correlated using linear mixed‐effects models.ResultsAposematic and non‐aposematic species neither differ in realised nor in potential geographic range size. There was no effect on body size.Main ConclusionsThe role of aposematism is not yet as clear as suggested and determinants of poison frog range sizes are multifaceted. A more integrative approach is needed using the information on behaviour, predation risk, and reproductive biology to assess the role of aposematism on observed species distributions. Such data are not yet available for most species, neither poison frogs nor other aposematic animals.