bluuebunny/crossref_metadata_2025_split huggingface dataset:
Population genomic response to geographic gradients by widespread and endemic fishes of the Arabian Peninsula
Authors: DiBattista Joseph D. , Saenz‐Agudelo Pablo , Piatek Marek J. , Cagua Edgar Fernando , Bowen Brian W. , Choat John Howard , Rocha Luiz A. , Gaither Michelle R. , Hobbs Jean‐Paul A. , Sinclair‐Taylor Tane H. , McIlwain Jennifer H. , Priest Mark A. , Braun Camrin D. , Hussey Nigel E. , Kessel Steven T. , Berumen Michael L. 
Published: April 2020

AbstractGenetic structure within marine species may be driven by local adaptation to their environment, or alternatively by historical processes, such as geographic isolation. The gulfs and seas bordering the Arabian Peninsula offer an ideal setting to examine connectivity patterns in coral reef fishes with respect to environmental gradients and vicariance. The Red Sea is characterized by a unique marine fauna, historical periods of desiccation and isolation, as well as environmental gradients in salinity, temperature, and primary productivity that vary both by latitude and by season. The adjacent Arabian Sea is characterized by a sharper environmental gradient, ranging from extensive coral cover and warm temperatures in the southwest, to sparse coral cover, cooler temperatures, and seasonal upwelling in the northeast. Reef fish, however, are not confined to these seas, with some Red Sea fishes extending varying distances into the northern Arabian Sea, while their pelagic larvae are presumably capable of much greater dispersal. These species must therefore cope with a diversity of conditions that invoke the possibility of steep clines in natural selection. Here, we test for genetic structure in two widespread reef fish species (a butterflyfish and surgeonfish) and eight range‐restricted butterflyfishes across the Red Sea and Arabian Sea using genome‐wide single nucleotide polymorphisms. We performed multiple matrix regression with randomization analyses on genetic distances for all species, as well as reconstructed scenarios for population subdivision in the species with signatures of isolation. We found that (a) widespread species displayed more genetic subdivision than regional endemics and (b) this genetic structure was not correlated with contemporary environmental parameters but instead may reflect historical events. We propose that the endemic species may be adapted to a diversity of local conditions, but the widespread species are instead subject to ecological filtering where different combinations of genotypes persist under divergent ecological regimes.
Age of European silver eels during a period of declining abundance in Norway
Authors: Durif Caroline M. F. , Diserud Ola H. , Sandlund Odd Terje , Thorstad Eva B. , Poole Russell , Bergesen Knut , Escobar‐Lux Rosa H. , Shema Steven , Vøllestad Leif Asbjørn 
Published: April 2020

AbstractThe European eel (Anguilla anguilla) is critically endangered throughout its range. Knowledge about age distribution of future spawners (silver eels) is essential to monitor the status and contribute to the recovery of this species. Determination of age in anguillid eels is challenging, especially in eels from the northern part of the distribution area where growth is slow and age at maturation can be up to 30 years or more. Eels from the river Imsa in Norway have been monitored since 1975, and this reference time series has been used to assess the stock at the European level. Population dynamics in this catchment were analyzed during the late 1980s by estimating ages on whole cleared otoliths. However, techniques for revealing annual increments on otoliths have evolved over the years sometimes yielding significant differences in age estimates. In this study, the historical otolith data were reanalyzed using a grinding and polishing method rather than reading the whole otolith. The new age estimates were considerably higher than the previous ones, sometimes by up to 29 years. Since the 1980s, mean age of silver eels only slightly increased (from 19 to 21 years in the 2010s). This was mainly due to the disappearance of younger silver eels (<15 years) in the 2010s. The new age estimates agreed with the steep decline in recruitment which occurred in the late 1980s in the Imsa catchment. Mean growth (30 mm/year, min–max: 16–64 mm/year) has not changed since the 1980s, although density in the catchment has decreased. Revealing and reading age of slow‐growing eels remain a challenge but adding a measure of otolith reading uncertainty may improve age data collection and contribute to recovery measures for this species.
Relationships between survival and habitat suitability of semi‐aquatic mammals
Authors: Barela Isidro , Burger Leslie M. , Taylor Jimmy , Evans Kristine O. , Ogawa Ryo , McClintic Lance , Wang Guiming 
Published: April 2020

AbstractSpatial distribution and habitat selection are integral to the study of animal ecology. Habitat selection may optimize the fitness of individuals. Hutchinsonian niche theory posits the fundamental niche of species would support the persistence or growth of populations. Although niche‐based species distribution models (SDMs) and habitat suitability models (HSMs) such as maximum entropy (Maxent) have demonstrated fair to excellent predictive power, few studies have linked the prediction of HSMs to demographic rates. We aimed to test the prediction of Hutchinsonian niche theory that habitat suitability (i.e., likelihood of occurrence) would be positively related to survival of American beaver (Castor canadensis), a North American semi‐aquatic, herbivorous, habitat generalist. We also tested the prediction of ideal free distribution that animal fitness, or its surrogate, is independent of habitat suitability at the equilibrium. We estimated beaver monthly survival probability using the Barker model and radio telemetry data collected in northern Alabama, United States from January 2011 to April 2012. A habitat suitability map was generated with Maxent for the entire study site using landscape variables derived from the 2011 National Land Cover Database (30‐m resolution). We found an inverse relationship between habitat suitability index and beaver survival, contradicting the predictions of niche theory and ideal free distribution. Furthermore, four landscape variables selected by American beaver did not predict survival. The beaver population on our study site has been established for 20 or more years and, subsequently, may be approaching or have reached the carrying capacity. Maxent‐predicted increases in habitat use and subsequent intraspecific competition may have reduced beaver survival. Habitat suitability‐fitness relationships may be complex and, in part, contingent upon local animal abundance. Future studies of mechanistic SDMs incorporating local abundance and demographic rates are needed.
Within‐season changes in habitat use of forest‐dwelling boreal bats
Authors: Vasko Ville , Blomberg Anna S. , Vesterinen Eero J. , Suominen Kati M. , Ruokolainen Lasse , Brommer Jon E. , Norrdahl Kai , Niemelä Pekka , Laine Veronika N. , Selonen Vesa , Santangeli Andrea , Lilley Thomas M. 
Published: April 2020

AbstractBats utilize forests as roosting sites and feeding areas. However, it has not been documented how bats utilize these habitats in the boreal zone with methods afforded by recent technological advances. Forest structure and management practices can create a variety of three‐dimensional habitats for organisms capable of flight, such as bats. Here, we study the presence of boreal bats in a forest forming a mosaic of different age classes, dominant tree species, canopy cover, soil fertility, and other environmental variables, throughout their active season in the summer using passive ultrasound detectors. Our results indicate a preference for mature forest by Eptesicus nilssonii and a pooled set of Myotis bats. Both groups of bats also showed temporal changes in their habitat use regarding forest age. In June and July, both groups occurred more often in mature than young forests, but from August onwards, the difference in occurrence became less evident in Myotis and disappeared completely in E. nilssonii. In addition, E. nilssonii was more often present in forests with low canopy cover, and its occurrence shifted from coniferous forests to deciduous forests during the season. The results reflect the within‐season dynamics of bat communities and their ability to utilize different types of forest as environmental conditions change. Yet, the results most importantly emphasize the importance of mature forests to bat diversity and the need to conserve such environments in the boreal zone.
More widespread alien tree species do not have larger impacts on regeneration of native tree species in a tropical forest reserve
Authors: Kiswaga Samson Aman Samson , Mbwambo John Richard , Shirima Deo , Mndolwa Ahmed S. , Schaffner Urs , Eschen René 
Published: April 2020

AbstractThere is insufficient information regarding the factors affecting the environmental impacts of alien species. In particular, little is known about whether there is any relationship between the invasiveness (establishment and spread) of an introduced species and its per capita impact. We experimentally assessed the relationship between the extent of spread of up to 29 alien plant species and their impact on recruitment of native tree species in Amani Botanical Garden, Tanzania. We also studied the effects of allelochemicals of selected alien on native plant species to assess potential mechanisms of impact. We found no relationship between the extent of spread of an alien tree species and their impact on seed germination, seedling survival, and seedling communities of native trees in their understory, and no indication that allelochemicals consistently explain their effects on recruitment of the studied species. These results suggest that extent of spread cannot be used as a proxy for impact. Hence, managers should continue assessing both the spread and the impact of alien species when prioritizing alien species for management.
Distributed average consensus optimization for cooperative spectrum sensing in cognitive radio ad hoc networks
Authors: Gabriel Hernandes Aislan , Abrão Taufik 
Published: April 2020

SummaryIn this article, we develop a parameter and optimization analyses aiming at characterizing the performance of cooperative spectrum sensing (CSS) based on the distributed average consensus (DAC), taking into account the network topology effect, represented by adjacency matrices in cognitive radio ad hoc networks. The CSS performance is analyzed by the probability of detection, probability of false alarm, and probability of miss detection, besides the decision threshold and the number of collected samples. In this work, all secondary users are equipped with a simple energy detector. Despite the DAC technique has been successfully deployed in the distributed CSS context, however, a full analytical description taking into account the joint effects of the network topology and all the optimized system parameters remains unknown. Moreover, the CSS network decision threshold was optimized using the error probability minimization criterion. Numerical results deploying extensive Monte Carlo simulations have corroborated the proposed analytical expressions.
Correlation analysis between filamentous fungi and chemical compositions in a pu‐erh type tea after a long‐term storage
Authors: Zhou Binxing , Ma Cunqiang , Ren Xiaoying , Xia Tao , Zheng Chengqin , Liu Xiaohui 
Published: April 2020

AbstractStorage environment caused the difference between Jinhua Pu‐erh tea (JPT) and General Pu‐erh tea. In this study, fungal flora and chemical compositions were analyzed. The results showed that storage environment caused significant (p < .05) differences of theaflavins (TF), theabrownins (TB), tea polyphenols (TP), and water‐soluble sugars (WSS), and a highly significant (p < .01) difference of thearubigins (TR). Aspergillus niger, Aspergillus pallidofulvus, Aspergillus sesamicola, Penicillium manginii, and Aspergillus tamarii were isolated from Pu‐erh teas and identified based on colony characteristics and ITS, β‐tubulin, and calmodulin gene sequences, respectively. A. pallidofulvus, A. sesamicola, and P. manginii were dominant fungi in JPT and generated macroscopic yellow cleistothecia after a long‐term storage. Correlation analysis showed that dominant fungi exhibited significantly (p < .05 or p < .01) positive or negative corrections with TF, TB, TP, WSS, TR, and gallic acid. This study revealed dominant fungi including A. pallidofulvus, A. sesamicola, and P. manginii and their effects on given chemical compositions.
Volatility forecasts embedded in the prices of crude‐oil options
Authors: Gilder Dudley , Tsiaras Leonidas 
Published: April 2020

AbstractThis paper evaluates the ability of alternative option‐implied volatility measures to forecast crude‐oil return volatility. We find that a corridor implied volatility measure that aggregates information from a narrow range of option contracts consistently outperforms forecasts obtained by the popular Black–Scholes and model‐free volatility expectations, as well as those generated by a realized volatility model. This measure ranks favorably in regression‐based tests, delivers the lowest forecast errors under different loss functions, and generates economically significant gains in volatility timing exercises. Our results also show that the Chicago Board Options Exchange's “oil‐VIX” index performs poorly, as it routinely produces the least accurate forecasts.
Prevalence and determinants of loneliness in people living with dementia: Findings from the IDEAL programme
Authors: Victor Christina R. , Rippon Isla , Nelis Sharon M. , Martyr Anthony , Litherland Rachael , Pickett James , Hart Nicola , Henley Josie , Matthews Fiona , Clare Linda ,   IDEAL programme team
Published: April 2020

ObjectiveTo establish the prevalence and determinants of loneliness among people living with dementia.MethodsUsing data from the baseline wave of the Improving the experience of Dementia and Enhancing Active Life (IDEAL) cohort study, we examined the prevalence and predictors of loneliness in 1547 people with mild‐to‐moderate dementia. Loneliness was assessed using the six‐item De Jong Gierveld loneliness scale.ResultsAbout 30.1% of people with dementia reported feeling moderately lonely and 5.2% severely lonely. Depressive symptoms and increased risk of social isolation were associated with both moderate and severe loneliness. Those living alone were more likely to experience severe loneliness as were those reporting poorer quality of life. Marital status was not associated with loneliness nor were dementia diagnosis or cognitive function.ConclusionsThis is one of the few large‐scale studies to explore the prevalence of and determinants of loneliness among people living with dementia. Social isolation, depression and living alone were associated with experiencing loneliness. Longitudinal studies are needed to determine the directionality of these associations.
Joint trajectories of cognition and gait speed in Mexican American and European American older adults: The San Antonio longitudinal study of aging
Authors: Gonzales Mitzi M. , Wang Chen‐Pin , Quiben Myla , MacCarthy Daniel , Seshadri Sudha , Jacob Mini , Hazuda Helen 
Published: April 2020

AbstractObjectivesCognitive decline and gait speed slowing are independent predictors of disability and mortality. While both factors increase in prevalence with advancing age, little is known about their combined patterns of change. The study goal was to identify joint trajectories of cognition and gait speed within an aging bi‐ethnic cohort of Mexican Americans and European Americans.Methods/DesignParticipants included 182 Mexican Americans and 188 European Americans, ages 65 to 74, who were followed over a mean of 9.5 years. Cognition was assessed with the mini‐mental state examination and gait speed was examined with a timed 10‐ft walk. Joint trajectory classes of cognition and gait speed were identified with latent growth mixture modeling. Odd‐ratios assessed predictors for trajectory classes.ResultsThree latent trajectory classes were identified: (a) relatively stable cognition and gait (termed stable cognition and gait class, 65.4%); (b) deteriorating cognition and gait (termed cognitive and physical vulnerability class, 22.2%); (c) stable cognition and deteriorating gait (termed physical vulnerability class, 12.4%). The odds of classification in the cognitive and physical vulnerability class vs stable cognition and gait class was associated with Mexican American ethnicity (OR = 3.771, P = .016), age (OR = 1.186, P = .017), income (OR = 0.828, P = .029), education (OR = 0.703, P < .001), and diabetes (OR = 4.547, P = .010). The odds of classification in the physical vulnerability class was associated with female sex (OR = 6.481, P = .004) and body mass index (OR = 1.118, P = .025).ConclusionsThe trajectories of cognition and gait speed were generally parallel, suggesting the two domains may act synergistically to shape important health outcomes. Socioeconomic disparities and Mexican American ethnicity independently conferred risk for accelerated decline.
Transition Metal‐Free Alkyne‐Aldehyde Reductive C−C Coupling trough Cascade Borylation/Olefin Isomerization
Authors: Khan Imran , Luo Zhibin , Xu Yin , Xie Jimin , Zhu Weihua , Liu Bin 
Published: April 2020

AbstractA direct approach to γ‐keto esters through cascade alkyne‐aldehyde reductive C−C coupling of propargyl esters and aromatic aldehydes under transition‐metal‐free (TM‐free) fashion was developed. Compared with multistep processes, this procedure provides a fast path using commercially available materials and could be handled conveniently to produce various γ‐keto esters in moderate yields.
The mRNA‐Binding Protein HuR Is a Kinetically‐Privileged Electrophile Sensor
Authors: Poganik Jesse R. , Van Hall‐Beauvais Alexandra K. , Long Marcus J. C. , Disare Michael T. , Zhao Yi , Aye Yimon 
Published: April 2020

AbstractThe key mRNA‐binding proteins HuR and AUF1 are reported stress sensors in mammals. Intrigued by recent reports of sensitivity of these proteins to the electrophilic lipid prostaglandin A2 and other redox signals, we here examined their sensing abilities to a prototypical redox‐linked lipid‐derived electrophile, 4‐hydroxynonenal (HNE). Leveraging our T‐REX electrophile delivery platform, we found that only HuR, and not AUF1, is a kinetically‐privileged sensor of HNE in HEK293T cells, and sensing functions through a specific cysteine, C13. Cells depleted of HuR, upon treatment with HNE, manifest unique alterations in cell viability and Nrf2‐transcription‐factor‐driven antioxidant response (AR), which our recent work shows is regulated by HuR at the Nrf2‐mRNA level. Mutagenesis studies showed that C13‐specific sensing alone is not sufficient to explain HuR‐dependent stress responsivities, further highlighting a complex context‐dependent layer of Nrf2/AR regulation through HuR.
Experimental study of exergetic performance of Al2O3 nanofluid in a double‐pipe heat exchanger fitted by a new modified twisted tape
Authors: Shirazi Robab 
Published: April 2020

AbstractThe use of nanofluids and surface enhancers today are among the new technologies used to increase heat transfer. In this study, heat transfer phenomena in heat exchanger were investigated using Al2O3 nanoparticles and modified spiral band as flow turbulator. Results are verified with well‐known correlations. The results show that the tube with cross‐hollow twisted tape inserts has the best exergetic performance for different hollow widths of the tape. Clearance, which is defined as the width between the tube and twisted tape, also affects the heat transfer performance. The smaller the clearance, the better is the exergetic performance. The tube can achieve the best exergetic performance when the number of unilateral twisted tapes is four. The results showed that increasing nanofluid concentration improves exergetic performance.
CFD analysis of the thermal losses on the upper part of a flat solar collector
Authors: Mekahlia Alaeddine , Boumaraf Latra , Abid Chérifa 
Published: April 2020

AbstractTo investigate the reduction of heat losses on the upper part of a flat solar collector, a two‐dimensional study was carried out by CFD analysis using Fluent. For this purpose, the heat transfer behavior in the air gap over a wide range of thicknesses of the latter (1‐20 mm) and the addition of a second glass cover fixed at midheight of the air gap spacing have been investigated. For small thicknesses of the air gap (1‐8 mm), the heat transfer is essentially conductive. An increase in the thickness leads to the intensification of the natural convection which induces high thermal losses. The simulation results have shown that the addition of a second cover glazing leads to the weakening of the natural convection and thus to an average enhancement of the solar collector temperature over the range of thicknesses studied of approximately 17%. The overall thermal losses coefficient is then reduced by an average of 26% compared with the single‐glazed solar collector. They have also shown that the thickness of the air gaps resulting in the minimum overall heat losses is 8 mm and that the thickness of the second glass cover has no significant effect on these results. In addition, this study has highlighted the importance of taking into account the radiation heat transfer in establishing the thermal balance of a flat solar collector. Indeed, this consideration leads to an average decrease of the absorber temperature of about 30%.
Transient streambed hydraulic conductivity in channel and bar environments, Loup River, Nebraska
Authors: Korus Jesse T. , Fraundorfer Wilhelm P. , Gilmore Troy E. , Karnik Kelsey 
Published: April 2020

AbstractStreambed hydraulic conductivity (K) and vertical K (K
v) are key controls on groundwater and surface water exchange and biogeochemical fluxes through the hyporheic zone, but drivers of transient hydraulic properties in different fluvial environments are poorly understood. This study combines hydrogeology, geophysics, and sedimentology to reveal mechanisms of K and K
v transience in the upper 0.5 m of a sandy streambed during low discharge. Hydraulic tests (44 slug tests, 130 falling‐head permeameter tests) and 130 grain‐size analyses were repeated three times over 8 weeks on a 1,200 m2 grid spanning: (a) a channel with continuously flowing water and mobile bed load; (b) an adjacent mid‐channel bar that was stationary and infrequently submerged. Aerial photographs and ground‐penetrating radar show scour and complete reworking of fluvial sediments in the channel. Bar sediments below the water table remained immobile, but infrequent flows of moderate discharge reworked the uppermost few centimetres of the bar top. Despite differences in sediment mobility and stream flow characteristics across environments, K and K
v exhibited order‐of‐magnitude differences in spatial heterogeneity and temporal variability in both the channel and bar. Mean K and K
v values in the channel were comparatively stable over time. In the immobile bar, mean K declined 20% and K
v declined 26% after increased discharge temporarily inundated the bar. Grain‐size distributions were steady across both environments over time, but repeat geophysical surveys of the bar show a decrease in electrical conductivity, likely from porosity reduction. These findings suggest that sediment dynamics and stream flow characteristics in different streambed environments are important drivers of K transience during low discharge conditions. Specifically, pore clogging can be an important mechanism of transience over short durations (weeks to months) in immobile sediments subject to infrequent flows and minor reworking.