bluuebunny/crossref_metadata_2025_split huggingface dataset:
Systematic realization of low‐frequency third‐order sinusoidal oscillators
Authors: Raj Ajishek , Kumar Pragati , Bhaskar Data Ram 
Published: July 2021

SummaryIn this paper, a systematic realization technique for low‐frequency third‐order sinusoidal oscillators (TOSOs) with independent control of condition of oscillation (CO) and frequency of oscillation (FO), employing minimum number of resistors and grounded capacitors, has been presented. Twelve new matrices have been systematically derived. These 12 matrices lead to four distinct low‐frequency sinusoidal oscillators with independent control of CO and FO. Workability of these proposed oscillators has been validated through experimental results of low‐frequency oscillations operating at 3.03 Hz, realized with off‐the‐shelf available IC AD844 type CFOAs. The total harmonic distortion of the presented oscillators is below 0.74%, and the frequency deviations are less than 1.06%.
History of canids in Chile and impacts on prey adaptations
Authors: Silva Rochefort Benjamín , Root‐Bernstein Meredith 
Published: July 2021

AbstractArtiodactyl prey species of Chile, especially guanacos (Lama guanicoe), are reported to be very susceptible to predation by pack‐hunting feral dogs. It has been previously suggested that guanacos and endemic South American deer may have evolved in the absence of pack‐hunting cursorial predators. However, the paleoecology of canid presence in southern South America and Chile is unclear. Here, we review the literature on South American and Chilean canids, their distributions, ecologies, and hunting behavior. We consider both wild and domestic canids, including Canis familiaris breeds. We establish two known antipredator defense behaviors of guanacos: predator inspection of ambush predators, for example, Puma concolor, and rushing at and kicking smaller cursorial predators, for example, Lycalopex culpaeus. We propose that since the late Pleistocene extinction of hypercarnivorous group‐hunting canids east of the Andes, there were no native species creating group‐hunting predation pressures on guanacos. Endemic deer of Chile may have never experienced group‐hunting selection pressure from native predators. Even hunting dogs (or other canids) used by indigenous groups in the far north and extreme south of Chile (and presumably the center as well) appear to have been used primarily within ambush hunting strategies. This may account for the susceptibility of guanacos and other prey species to feral dog attacks. We detail seven separate hypotheses that require further investigation in order to assess how best to respond to the threat posed by feral dogs to the conservation of native deer and camelids in Chile and other parts of South America.
Floral attraction and flower visitors of a subcanopy, tropical rainforest tree, Fontainea picrosperma
Authors: Grant Elektra L. , Wallace Helen M. , Brooks Peter R. , Burwell Chris , Reddell Paul W. , Ogbourne Steven M. 
Published: July 2021

Abstract

Flowering plants in tropical rainforests rely heavily on pollen vectors for successful reproduction. Research into pollination systems in tropical rainforests is dominated by canopy species, while subcanopy plant–pollinator interactions remain under‐represented. The microclimate beneath the rainforest canopy is characterized by low light levels and is markedly different from the canopy environment that receives more light energy.

We studied the floral attractants and floral visitors of a dioecious, subcanopy tree, Fontainea picrosperma (Euphorbiaceae), in the Wet Tropics bioregion of northern Queensland, Australia.

We found that wind pollination is rare and male and female flowers do not produce nectar. Female flowers are likely pollinated due to their perceptual similarity to pollen‐offering male flowers. Female flowers had the same scent profile as male flowers, and floral scent was an important floral attractant that acted to regulate pollinator behavior. The two most abundant scent compounds present in the floral bouquet were benzyl alcohol and 4‐oxoisophorone. These compounds are ubiquitous in nature and are known to attract a wide variety of insects. Both day‐time and night‐time pollinators contributed to successful pollen deposition on the stigma, and diurnal flower visitors were identified from several orders of insects including beetles, flies, predatory wasps, and thrips. Fontainea picrosperma is therefore likely to be pollinated by a diverse array of small insects.

Synthesis. Our data indicate that F. picrosperma has a generalist, entomophilous pollination syndrome. The rainforest subcanopy is a distinctive environment characterized by low light levels, low or turbulent wind speeds, and relatively high humidity. Female flowers of F. picrosperma exhibit cost‐saving strategies by not producing nectar and mimicking the smell of reward‐offering male flowers. Insects opportunistically forage on or inhabit flowers, and pollination occurs from a pool of small insects with low energy requirements that are found beneath the rainforest canopy.
Role of carryover effects in conservation of wild Pacific salmon migrating regulated rivers
Authors: Gosselin Jennifer L. , Buhle Eric R. , Van Holmes Christopher , Beer W. Nicholas , Iltis Susannah , Anderson James J. 
Published: July 2021

AbstractDetermining which factors are most effective for mitigative strategies in conservation management can be difficult for species with complex life cycles. Salmon (Oncorhynchusspp.) migrating through a hydroelectric power system experience conditions that can affect their survival directly within a life stage and indirectly in subsequent life stages through carryover effects. We quantified the association of covariates with survival across life stages of Chinook salmon (O. tshawytscha): juveniles migrating downstream, juveniles in the estuary, subadults in the ocean, and adults migrating upstream. We applied a hierarchical Bayesian mark–recapture model to ~400,000 wild Snake River Chinook salmon (Pacific Northwest, USA). Modeled covariates of survival included migration timing, river temperature, flow, percent of water spilled over dams, snow water equivalent, juvenile fish transportation, juvenile fish length, dam powerhouse passage, sea surface temperature, and the North Pacific Gyre Oscillation. By analyzing these covariates in a unified model, we evaluated their relationships to survival within and across life stages in a common currency. Among direct effects, the negative relationship of sea surface temperature to ocean survival had the largest marginal effect size. Carryover effects also had substantial marginal effect sizes. Ocean survival was associated positively with juvenile length and snow water equivalent and negatively with river temperature. In comparison, direct effects on juvenile and adult survival generally showed smaller marginal effect sizes. Both juvenile and adult survival were negatively associated with river temperature. Juvenile survival increased with fish length, while adult survival was positively related to flow and negatively to percent water spilled at dams. The greatest variability in survival, however, was in the ocean stage. Thus, as the ocean continues to warm and as the human population exerts more pressure on the ecosystem, carryover effects will be increasingly important for recovering salmon and other migratory species.
Climate warming threatens the persistence of a community of disturbance‐adapted native annual plants
Authors: Reed Paul B. , Bridgham Scott D. , Pfeifer‐Meister Laurel E. , DeMarche Megan L. , Johnson Bart R. , Roy Bitty A. , Bailes Graham T. , Nelson Aaron A. , Morris William F. , Doak Daniel F. 
Published: July 2021

AbstractWith ongoing climate change, populations are expected to exhibit shifts in demographic performance that will alter where a species can persist. This presents unique challenges for managing plant populations and may require ongoing interventions, including in situ management or introduction into new locations. However, few studies have examined how climate change may affect plant demographic performance for a suite of species, or how effective management actions could be in mitigating climate change effects. Over the course of two experiments spanning 6 yr and four sites across a latitudinal gradient in the Pacific Northwest, United States, we manipulated temperature, precipitation, and disturbance intensity, and quantified effects on the demography of eight native annual prairie species. Each year we planted seeds and monitored germination, survival, and reproduction. We found that disturbance strongly influenced demographic performance and that seven of the eight species had increasingly poor performance with warmer conditions. Across species and sites, we observed 11% recruitment (the proportion of seeds planted that survived to reproduction) following high disturbance, but just 3.9% and 2.3% under intermediate and low disturbance, respectively. Moreover, mean seed production following high disturbance was often more than tenfold greater than under intermediate and low disturbance. Importantly, most species exhibited precipitous declines in their population growth rates (λ) under warmer‐than‐ambient experimental conditions and may require more frequent disturbance intervention to sustain populations. Aristida oligantha, a C4 grass, was the only species to have λ increase with warmer conditions. These results suggest that rising temperatures may cause many native annual plant species to decline, highlighting the urgency for adaptive management practices that facilitate their restoration or introduction to newly suitable locations. Frequent and intense disturbances are critical to reduce competitors and promote native annuals’ persistence, but even such efforts may prove futile under future climate regimes.
Plant traits and soil fertility mediate productivity losses under extreme drought in C3 grasslands
Authors: Luo Wentao , Griffin‐Nolan Robert J. , Ma Wang , Liu Bo , Zuo Xiaoan , Xu Chong , Yu Qiang , Luo Yahuang , Mariotte Pierre , Smith Melinda D. , Collins Scott L. , Knapp Alan K. , Wang Zhengwen , Han Xingguo 
Published: July 2021

AbstractExtreme drought decreases aboveground net primary production (ANPP) in most grasslands, but the magnitude of ANPP reductions varies especially in C3‐dominated grasslands. Because the mechanisms underlying such differential ecosystem responses to drought are not well resolved, we experimentally imposed an extreme 4‐yr drought (2015–2018) in two C3 grasslands that differed in aridity. These sites had similar annual precipitation and dominant grass species (Leymus chinensis) but different annual temperatures and thus water availability. Drought treatments differentially affected these two semiarid grasslands, with ANPP of the drier site reduced more than at the wetter site. Structural equation modeling revealed that community‐weighted means for some traits modified relationships between soil moisture and ANPP, often due to intraspecific variation. Specifically, drought reduced community mean plant height at both sites, resulting in a reduction in ANPP beyond that attributable to reduced soil moisture alone. Higher community mean leaf carbon content enhanced the negative effects of drought on ANPP at the drier site, and ANPP–soil‐moisture relationships were influenced by soil C:N ratio at the wetter site. Importantly, neither species richness nor functional dispersion were significantly correlated with ANPP at either site. Overall, as expected, soil moisture was a dominant, direct driver of ANPP response to drought, but differential sensitivity to drought in these two grasslands was also related to soil fertility and plant traits.
Techno‐economic assessment and sensitivity analysis of biodiesel production intensified through hydrodynamic cavitation
Authors: Gholami Ali , Pourfayaz Fathollah , Saifoddin Amirali 
Published: July 2021

AbstractSince the last two decades, hydrodynamic cavitation has been introduced as one of the most efficient approaches to intensify transesterification. However, the number of industrial biodiesel plants utilizing this process is still minimal. One primary reason is the lack of information on both its economic and environmental impacts. In this study, a simulation‐based model was developed using Aspen HYSYS V8.4 for comparing flow‐through hydrodynamic cavitation with conventional mechanical stirring in terms of total capital investment, total product cost, net present value, modified internal rate of return, materials, and energy consumption. The two plants operated 7920 hours per year and produced 100 tons of biodiesel per day from fresh sunflower oil. The results showed that total capital investment and total product cost for hydrodynamic cavitation were roughly 65% and 10% lower than those for the mechanical stirring process, respectively. While the net present value was negative for the mechanical stirring, a positive net present value and a modified internal rate of return of 25.61% were obtained in the hydrodynamic cavitation process. Performing sensitivity analysis using the Box‐Behnken design and response surface methodology revealed that net present value was most affected by the linear term of the sunflower oil price. It was also found that hydrodynamic cavitation could significantly reduce materials and energy consumption, owing to higher reactor yield and lower alcohol and catalyst consumption.
Quantifying sediment connectivity: Moving toward a holistic assessment through a mixed methods approach
Authors: Turley Mike , Hassan Marwan A. , Slaymaker Olav 
Published: July 2021

AbstractThe sediment connectivity concept is particularly suitable for tackling complex, multidisciplinary questions through systems thinking. However, it is unclear how to directly measure connectivity, and so proxy variables are often applied by indices to provide estimates. In this study, we critically evaluate a broad range of connectivity indices encompassing structural and functional connectivity as well as hillslope channel coupling. We then discuss their role in providing a more holistic estimation of connectivity within the Tahoma Creek Watershed, WA. Of the 14 km of channel below the glacier front, the upper 6 km (0–6 km) are coupled to the adjacent hillslopes. Coupled reaches correspond to regions with a high proportion of area contributing sediment and relatively high connectivity values, where all measures decrease in the downstream direction. A significant transition occurs near river kilometer 6. Here the valley bottom abruptly widens, deposition occurs, and the hillslopes become decoupled from the active channel. This transitional reach is also identified as a geomorphic hotspot based on the network structure. The lower 8 km of channel downstream of this reach are largely depositional and percent contributing area and connectivity values remain low, eventually reaching a minimum. Despite their limitations, we found each method to provide unique and useful information regarding connectivity. The effect of scale and event magnitude on connectivity is illustrated. We also found vegetation, topographic characteristics, and network structure to be important in high‐gradient glacio‐volcanic landscapes. The choice of an index will depend on the research objectives, data availability, and the proxy variables that best describe the variability within the defined area.
Seasonal fluxes and sediment routing in tropical catchments affected by nickel mining
Authors: Domingo Justine Perry T. , Attal Mikaël , Mudd Simon M. , Ngwenya Bryne T. , David Carlos Primo C. 
Published: July 2021

AbstractAn important gap in the management of land erosion in mining‐affected areas is the understanding of the entire sediment routing system and the links between sources and storage at the catchment scale. In this study, we examine sediment delivery and its seasonality in the nickel mining‐affected Santa Cruz and Pamalabawan catchments in the Philippines. We monitored discharge, suspended sediment concentrations and suspended sediment loads across 13 sub‐catchments with contrasting degrees of mining influence from June 2018 to July 2019. First, we show the importance of the size of the area that has been physically disturbed within our sub‐catchments, with as little as 10–22% of relative disturbance area being enough to generate four‐fold to eight‐fold increase in the sediment yield relative to less disturbed and pristine areas. We found that sub‐catchments with > 10% disturbance exhibit the highest sediment yields (15.5 ± 44.7 t km−2 d−1) compared with sub‐catchments with < 10% disturbance (3.6 ± 17.7 t km−2 d−1) and undisturbed catchments (2.0 ± 5.7 t km−2 d−1). We also show that sediment flushing predominantly occurs in the most disturbed sub‐catchments at the onset of the wet season. A small number of flood events transports the bulk of the sediment, with hysteresis effects being most pronounced in disturbed areas. Lastly, we show that floodplain sediment recycling exerts a key control on sediment delivery at both reach and catchment scales, with the relative contribution of floodplain sources to the sediment budget becoming dominant in the latter stages of the wet season‐ up to 89% of the total sediment export per storm event. This study highlights the importance of both degree of disturbance and sediment pathways in controlling sediment transport in mining‐disturbed areas, and that considering the entire sediment routing system including intermediate stores is crucial to optimizing existing and future measures against siltation and potential contamination of trace metals and metalloids downstream of mining areas.
Vitamin D3 alleviates cognitive impairment through regulating inflammatory stress in db/db mice
Authors: Tan Xiaomu , Gao Lifang , Cai Xiaxia , Zhang Mingyuan , Huang Dongxu , Dang Qinyu , Bao Lei 
Published: July 2021

AbstractPatients with type 2 diabetes mellitus (T2DM) have a higher risk to develop cognitive impairment. Several studies reported the potential roles of vitamin D in prevention of cognitive impairment, but the mechanism remains unclear. The present study aims to investigate the protective effects of vitamin D3 on cognitive impairment in db/db mice and to explore the possible mechanism. Twelve‐week‐old male db/db mice were randomly administrated with low, medium, and high dose of vitamin D3 (LVD, MVD, and HVD groups, respectively) and equivalent volume vitamin D3 solvent (corn oil, DM group) intragastrically. Eight age‐matched db/m mice were given equivalent volume corn oil as normal group. After 16 weeks of vitamin D3 treatment, the concentrations of fasting serum glucose in three vitamin D3 groups (especially the 1,000 IU/kg·bw dose) were significantly decreased compared with DM group. Pathology revealed that the neuron damage was reduced in vitamin D3 groups. MVD intervention significantly shortened the escape latency on day 5 and extended time in the target quadrant. Mice in HVD group had significantly higher exploration time and discrimination index compared with the DM group mice. Moreover, vitamin D3 treatment has increased the phosphorylation of cAMP‐response element‐binding protein and the expression of brain‐derived neurotrophic factor and vitamin D receptor. This treatment, meanwhile, has decreased the expression of tumor necrosis factor‐α, the phosphorylation of inhibitor kappa Bα (IκBα), and nuclear factor‐κB p65 (NF‐κB p65) in the hippocampus of db/db mice. These results suggest that vitamin D3 alleviated cognitive impairment in the hippocampus of db/db mice. Down‐regulation of the NF‐κB signaling pathway‐related proteins IκBα and p65 might be one of the possible mechanisms.
Co‐ingestion of prescription drugs and alcohol in US adults aged 50 years or older
Authors: Schepis Ty S. , Ford Jason A. , McCabe Sean Esteban 
Published: July 2021

AbstractObjectiveTo examine prevalence of past‐month prescription drug misuse (PDM) and alcohol co‐ingestion and its correlates in adults age 50 or older.MethodsData were from the 2015–2018 US National Survey on Drug Use and Health (n = 35,190). PDM‐alcohol co‐ingestion was defined as prescription opioid, tranquilizer/sedative, or stimulant misuse while “drinking alcohol or within a couple of hours of drinking.” Co‐ingestion prevalence was estimated, and logistic and negative binomial regressions examined the sociodemographic, physical health, mental health, substance use, and substance use disorder (SUD) correlates of co‐ingestion.ResultsOver 344,000 adults aged 50 years or older (0.3%) engaged in past‐month PDM‐alcohol co‐ingestion, or 27.4% of those with past‐month PDM. Past‐month co‐ingestion was linked to greater past‐month alcohol use frequency and elevated adjusted odds ratios (aORs) for all examined substance use outcomes (e.g., non‐PDM SUD aOR = 21.8; 49.7% prevalence rate). The aOR for suicidal ideation was 506% higher in those with co‐ingestion than those without past‐year PDM.ConclusionsUS adults aged 50 years or older with past‐month PDM‐alcohol co‐ingestion are at high risk for SUD and concerning mental health symptoms. Screening for mental health and substance use treatment is warranted among aging adults with signs of PDM, especially involving co‐ingestion.
Consumer inflation expectations, income changes and economic downturns
Authors: Tsiaplias Sarantis 
Published: July 2021

SummaryUsing a novel, nationally representative dataset containing the expectations of over 300,000 Australians, individuals are shown to form expectations in a manner inadequately explained by popular expectation mechanisms. Approximately one in five individuals form inflation expectations that are negatively related to their own‐income changes, even after accounting for their level of optimism regarding future economic conditions and their observation of economic news. These individuals are more likely to be engaged in manual labour and to be on lower income brackets. The inflation expectations of such individuals rise, even as Phillips curve predictions of inflation fall. The findings are particularly important for inflation dynamics during economic downturns when large numbers of consumers are likely to heavily increase their inflation expectations, potentially resulting in large inflation surprises.
Mechanical performance of collagen gels is dependent on purity, α1/α2 ratio, and telopeptides
Authors: Slyker Leigh , Diamantides Nicole , Kim Jongkil , Bonassar Lawrence J. 
Published: July 2021

AbstractThis article describes the compositional, mechanical, and structural differences between collagen gels fabricated from different sources and processing methods. Despite extensive use of collagen in the manufacturing of biomaterials and implants, there is little information as to the variation in properties based on collagen source or processing methods. As such, differences in purity and composition may affect gel structure and mechanical performance. Using mass spectrometry, we assessed protein composition of collagen from seven different sources. The mechanics and gelation kinetics of each gel were assessed through oscillatory shear rheology. Scanning electron microscopy enabled visualization of distinct differences in fiber morphology. Mechanics and gelation kinetics differed with source and processing method and were found to correlate with differences in composition. Gels fabricated from telopeptide‐containing collagens had higher storage modulus (144 vs. 54 Pa) and faster gelation (251 vs. 734 s) compared to atelocollagens, despite having lower purity (93.4 vs. 99.8%). For telopeptide‐containing collagens, as collagen purity increased, storage modulus increased and fiber diameter decreased. As α1/α2 chain ratio increased, fiber diameter increased and gelation slowed. As such, this study provides an examination of the effects of collagen processing on key quality attributes for use of collagen gels in biomedical contexts.