bluuebunny/crossref_metadata_2025_split huggingface dataset:
Controls on the distribution and resilience ofQuercus garryana: ecophysiological evidence of oak's water‐limitation tolerance
Authors: Hahm W. Jesse , Dietrich William E. , Dawson Todd E. 
Published: May 2018

AbstractThe composition of forests in Western North America is changing. The decline in the shade‐intolerant Oregon white oak (Quercus garryana var. garryana) is attributed to increased competition with the tall‐growing Douglas fir (Pseudotsuga menziesii var. menziesii) as a result of widespread fire exclusion. In a warmer, drier future, both species will experience increased water stress, and their distribution will depend on ecophysiological adaptations to water limitation, of which little is known forQ. garryana. Here, we report a suite of new ecophysiological observations to better understand the oak's water‐limitation tolerance, in order to predict its fate in a changing climate. Our study site in the Central Belt of the Franciscan Formation in the Northern California Coast Ranges receives almost no rain in the leaf‐on growing season and has limited subsurface water storage capacity. In spite of low pre‐dawn water potentials (Ψ; to below −3.0 MPa), mature trees maintained high rates of sapflow. Sapflow continued due to a high Ψ gradient (≈1.6 MPa on average) at mid‐day between shoots and the subsurface (inferred from pre‐dawn measurements) throughout the dry season. Depletion and recharge of stored water in stem tissue and leaves helped to sustain transpiration. Leaves experienced low Ψ (below −4 MPa), and declining hydraulic conductance yet remained functional. Pressure–volume curve analyses revealed that the maintenance of positive turgor pressures in leaves at low Ψ may be attributable to dynamic adjustment due to changes in cell wall elasticity. The turgor loss point may be of limited use in delineating ecophysiological limits to growth and reproduction, as transpiration and apparently normal physiological behavior continued after pre‐dawn water potentials declined below turgor loss limits inferred from rehydrated leaves. These findings indicate thatQ. garryanais a water‐limitation‐tolerant tree species that maintains hydraulic function as subsurface water supply and atmospheric demand conditions exceed the ranges at whichP. menziesiican operate. These observations can be used to explainQ. garryana's extant species range and anticipate its likely resilience in a warmer climate.
Benthic–pelagic coupling and bottom‐up forcing in rocky intertidal communities along the Atlantic Canadian coast
Authors: Scrosati Ricardo A. , Ellrich Julius A. 
Published: May 2018

AbstractBenthic species from rocky intertidal systems are irregularly distributed along marine coastlines. Nearshore pelagic conditions often help to explain such variation, but most such studies have been done on eastern ocean boundary coasts. We investigated possible benthic–pelagic coupling along the Atlantic coast of Nova Scotia, a western ocean boundary coast. In 2014, we surveyed high‐intertidal habitats from nine wave‐exposed bedrock locations spanning 415 km of coastline. At each location in the spring, we measured the recruitment of barnacles and mussels, the two main filter‐feeders. Recruitment varied irregularly along the coast. Satellite data on coastal phytoplankton and particulate organic carbon (food for intertidal filter‐feeders and their pelagic larvae) and in‐situ data on sea surface temperature explained, to varying degrees, the geographic structure of recruitment. In turn, the summer abundance of barnacles and mussels was positively related to their spring recruitment. Ultimately, intertidal predator (dogwhelk) abundance was positively related to the recruitment and/or abundance of barnacles and mussels (the main prey of dogwhelks). Sea ice may also have influenced this predator–prey interaction. Drift ice leaving the Gulf of St. Lawrence in late winter strongly disturbed the northern surveyed locations, making barnacles (through high spring recruitment) the only food source for dogwhelks (which survived ice scour in crevices) in such places. Overall, this study supports the occurrence of benthic–pelagic coupling and bottom‐up forcing on this coast. Investigating the oceanographic drivers of pelagic food supply and seawater temperature should help to further understand how this large metacommunity is organized.
Permafrost and drought regulate vulnerability of Tibetan Plateau grasslands to warming
Authors: Yang Yan , Hopping Kelly A. , Wang Genxu , Chen Ji , Peng Ahui , Klein Julia A. 
Published: May 2018

AbstractThe Tibetan Plateau has the largest expanse of high‐elevation permafrost in the world, and it is experiencing climate warming that may jeopardize the functioning of its alpine ecosystems. Many studies have focused on the effects of climate warming on vegetation production and diversity on the Plateau, but their disparate results have hindered a comprehensive, regional understanding. From a synthesis of twelve warming experiments across the Plateau, we found that warming increased aboveground net primary production (ANPP) and vegetation height at sites with permafrost, but ANPP decreased with warming at non‐permafrost sites. Aboveground net primary production responded more negatively to warming under drier conditions, due to both annual drought conditions and warming‐induced soil moisture loss. Decreases in species diversity with warming were also larger at sites with permafrost. These results support the emerging understanding that water plays a central role in the functioning of cold environments and suggest that as ecosystems cross a threshold from permafrost to non‐permafrost systems, ANPP will decrease across a greater proportion of the Tibetan Plateau. This study also highlights the future convergence of challenges from permafrost degradation and grassland desertification, requiring new collaborations among these currently distinct research and stakeholder groups.
Habitat use is linked to resource‐specific performance of an ecologically important marsh predator
Authors: Rinehart S. A. , Long J. D. 
Published: May 2018

AbstractIt is commonly assumed that animals should preferentially use habitats that enhance their individual performance. However, there have been few attempts to empirically test the relationship between an animals’ habitat use and performance. This is surprising, since knowing about this connection should enhance our ability to predict the local population dynamics of ecologically important species. Here, we used three primary experiments to assess the relationship between habitat use and performance for an important insect consumer (ladybeetles). First, we used field manipulations of resource availability (i.e., scale insects and cordgrass pollen) to examine the habitat use of ladybeetle predators. Second, we conducted a series of no‐choice laboratory assays to compare the performance (fecundity and longevity) of ladybeetles on these different resources. Third, we quantified adult ladybeetle preference for olfactory cues from cordgrass with and without scale insects using a Y‐tube olfactometer. In the field, adult ladybeetles selectively used plots containing scale insects. In the laboratory, diets containing scale insects maximized both adult and larval ladybeetle longevity, and adult fecundity. Adult ladybeetles were attracted to chemical cues associated with scale insects over distances of 10s of centimeters. Overall, our findings suggest that the habitat use and performance of ladybeetles are strongly linked, with ladybeetles preferentially using habitats that maximize their individual performance.
Life history and habitat explain variation among insect pest populations subject to global change
Authors: Walter Jonathan A. , Ives Anthony R. , Tooker John F. , Johnson Derek M. 
Published: May 2018

AbstractPopulation dynamic responses to global change have varied widely among taxa. Most studies of population dynamics of insect pests focus on one or a few species, leaving open the question of whether changes in outbreak patterns are species‐specific or reveal predictable responses to global change, and what factors explain differences among populations. We analyzed 64 multi‐decadal time series of agricultural and forest pest insect populations in the United States. We first characterized populations according to long‐term trends, strength of population regulation, and cycle presence and length. We then asked whether these attributes could be predicted by geography, taxonomy, and life‐history traits. Roughly half of time series exhibited a long‐term trend, and agricultural pests were more likely to be declining, while forest pests were more likely to be increasing. Approximately one quarter of records exhibited periodic oscillations, and we used their statistical properties to infer whether the oscillations were environmentally forced or arose from density dependence. Insects hatching in early spring may be more strongly influenced by environmental forcing, for example, early springs or late spring frosts, than species hatching later. Our findings suggest roles of climate change, forest compositional change, and agricultural practices in driving long‐term change in pest populations.
Relationships among introduced parasites, host defenses, and gut microbiota of Galapagos birds
Authors: Knutie Sarah A. 
Published: May 2018

AbstractParasites can cause significant damage to their hosts. Hosts can reduce the damage that parasites cause by either resisting parasites (e.g., with an immune response) or tolerating parasites (e.g., with energy compensation). Recent work suggests that host‐associated microbiota (bacteria) affect parasites, and vice versa, which can be mediated by host defense mechanisms. Although there are many possible interactions among parasites, host defenses, and host‐associated microbiota, few studies have explored these interactions in non‐model systems. Such studies are important for understanding disease risk, especially when considering emerging diseases. The parasitic nest fly Philornis downsi, which was introduced to the Galapagos Islands, causes considerable damage to Darwin's finches. In contrast, P. downsi has little effect on tolerant hosts, such as Galapagos mockingbirds, which increase nestling provisioning to compensate for energy lost to the parasite. Although host defenses against P. downsi have been relatively well‐studied, the importance of host‐associated microbiota in host–P. downsi interactions is unknown. In this study, an experimental manipulation of P. downsi was used to test the effect of parasitism on the fecal bacterial community (proxy for the gut) of Galapagos mockingbird and Darwin's finch nestlings. The relationships between the bacterial community and nestling provisioning or the antibody response were also determined. Galapagos mockingbirds and Darwin's finches harbor different gut bacterial communities. P. downsi decreased bacterial diversity of mockingbird nestlings, presumably in response to increased provisioning, which was negatively correlated with bacterial diversity. Lower bacterial diversity was related to lower antibody levels in mockingbirds. In contrast, P. downsi did not affect bacterial communities of finch nestlings, but bacterial diversity was negatively related to antibody levels. Overall, this study demonstrates that introduced parasites can affect host‐associated bacterial communities and that host defenses can correlate with changes in the gut microbiota.
Calibration of a single‐diode performance model without a short‐circuit temperature coefficient
Authors: Campanelli Mark B. , Hamadani Behrang H. 
Published: May 2018

AbstractWe calibrate the seven parameters of a single‐diode model (SDM) for photovoltaic device performance using current‐voltage (I‐V) curves measured under controlled laboratory conditions over a matrix of nominal temperature and irradiance combinations. As described in previous modeling work, we do not use a short‐circuit temperature coefficient parameter, which depends on the often unknown insolation spectrum and whose validity may be questionable. Alternatively, we employ a rigorous temperature‐dependent extension of the spectral mismatch correction. This standard correction is routinely used by calibration laboratories to measure an effective irradiance ratio (i.e., a particular ratio of short‐circuit currents) using a calibrated reference device, thereby compensating for spectral effects of the irradiance and for any difference in spectral response between the test device and reference device. The calibrated SDM predicts the device's current at any prescribed voltage, temperature, and effective irradiance, and thus can predicts power and energy production under prescribed conditions. Our approach aligns well with the matched reference cell approach to outdoor I‐V curve measurements, while clarifying the requirements of a “matched” condition for the irradiance monitoring device(s). We find evidence for significant model discrepancy in the SDM, suggesting that model improvements and measurement intercomparisons are needed.
Numerical study of polyethylene burning in counterflow: Effect of pyrolysis kinetics and composition of pyrolysis products
Authors: Karpov A. I. , Korobeinichev O. P. , Bolkisev A. A. , Shaklein A. A. , Shmakov A. G. , Paletsky A. A. , Gonchikzhapov M. B. 
Published: May 2018

SummaryThe burning behavior of polyethylene in the counterflow of oxidizing air has been studied numerically with a coupled model describing feedback heat and mass transfer between gas‐phase flame and polymeric solid fuel. A 2‐dimensional elliptic equation in axisymmetric formulation (revealing the cylindrical shape of the polymer sample used in the experiment) has been employed to simulate heat transfer in solid fuel, and a set of 1‐dimensional hyperbolic equations has been used to determine the solid‐to‐gas conversion degree of the pyrolysis reaction. Four sets of products compositions and two modifications for the kinetic parameters of solid fuel pyrolysis reaction have been taken into account. Gas‐phase formulation is presented by set of 1‐dimensional conservation equations for multi‐component flow with detailed kinetic mechanism of combustion. The profiles of temperature and species concentrations in the flame zone have been calculated and compared with the results of experimental study of combustion of ultrahigh molecular weight polyethylene. Higher hydrocarbon composition (dodecane) has been found to show the best agreement between the temperature and species concentration profiles with the measurements, especially for the low‐level mass fractions of the by‐product components—propylene, butadiene, and benzene.
Memory assessment services and health‐related quality of life: 1‐year follow‐up
Authors: Park Min Hae , Smith Sarah C. , Ritchie Craig W. , Hendriks A.A. Jolijn , Black Nick 
Published: May 2018

ObjectivesOur group has already demonstrated that patients' health‐related quality of life (HRQL) improves in the first 6 months after their first appointment at memory assessment services (MASs), but the sustainability of such gains is unknown. We aimed to describe changes in patients' HRQL at 12 months after their first MAS appointment and to examine associations with patient and MAS characteristics.MethodsWe collected data from 702 patients and 452 lay caregivers at the first appointment and 12 months later. Multivariable linear regression was used to examine the relationships of change in HRQL (self‐reported and proxy‐reported) with patients' characteristics and use of post‐diagnostic interventions, and multilevel models were used to analyse the relationships of HRQL with MAS characteristics.ResultsIn the whole group, self‐reported HRQL improved over 12 months (+3.5 points, 95% CI 2.7 to 4.2). Among people diagnosed with dementia, improvement in HRQL was more than double that among those with mild cognitive impairment or no diagnosis. Proxy‐reported HRQL improved only in those diagnosed with dementia (+1.2 points, 95% CI 0.2 to 2.2). Changes in HRQL were not associated with any patient characteristics. The only feature of MASs associated with larger improvements in HRQL was the presence of advisory and support staff.ConclusionsImprovements in HRQL observed at 6 months are maintained up to 1 year after the first MAS appointment, more so among those who receive a diagnosis of dementia. Continued follow‐up will determine if the improvement is even longer lasting.
Young children embody the time of others in their time judgments: The role of the theory of mind
Authors: Hallez Quentin , Droit‐Volet Sylvie 
Published: May 2018

AbstractThis study investigated the ability of young children to embody other people's time in their time judgments. Children aged from 4 to 7 years had to learn target durations and to reproduce them with the presentation of static pictures of individuals whose posture or body shape suggested different body states (movement, movement with object, emotion, and aging). Their acquisition of an explicit theory of mind was also assessed using the Sally–Anne false belief test. All the children produced different durations as a function of perceived body states. However, the magnitude of time distortions with perceived body states was higher in children with explicit theory of mind. Our results suggest an early implicit and automatic mechanism that allows young children to integrate other people's body states into their time judgments, to be attuned to others. However, the development of the awareness of others' mental states also increases time sensitivity to their states.Highlights

Young children embody the time of others in their time judgments, and the development of the awareness of others' mental states improves this primitive ability.
Children were asked to reproduce target durations with static pictures of individuals whose posture suggested different body states. Their acquisition of an explicit theory of mind was also assessed using the Sally–Anne false belief test.
All the children produced different durations as a function of perceived body states. However, the magnitude of time distortions with perceived body states was higher in children with explicit theory of mind.
Farm Water Program: Using the Water Savings Calculator
Authors: Norman C. , Walters C. , McFarlane M. , Nicholson C. , Lawler D. 
Published: May 2018

AbstractCalculating the water savings expected to be realised from improvements to farm irrigation systems is an integral part of the Farm Water Program being delivered in northern Victoria, Australia. Water savings form the basis of works packages landowners undertake to improve water productivity of their irrigation systems. Through the Farm Water Program, landowners agree to transfer more than half of the water savings for environmental purposes in exchange for funding to do works. The Farm Water Program originated in 2009 following the introduction of an AU$300 million On‐Farm Irrigation Efficiency Program by the Australian government. The Goulburn Broken and North Central Catchment Management authorities, relevant Victoria government agencies and irrigation industry bodies formed a consortium to bid for funding to be used on properties across the Goulburn Murray Irrigation District of Victoria. The organisations have worked in partnership as the Farm Water Program and have successfully delivered 620 projects involving over 80 000 megalitres of water savings. The water savings calculator was developed using research findings conducted in the region and has been widely accepted and confirmed by landowners as they have developed projects. This paper describes the processes of using the water savings calculator to determine project water savings. Copyright © 2018 John Wiley & Sons, Ltd.
Validation of the Brief Sense of Community Scale among youth of color from an underserved urban community
Authors: Lardier David T. , Reid Robert J. , Garcia‐Reid Pauline 
Published: May 2018

AbstractNeighborhood sense of community (SOC) is a key construct in the community psychology literature. While the research on neighborhood SOC has progressed significantly, there is a need to further validate the Brief Sense of Community Scale (BSCS) among youth. A critical area of scholarship, therefore, is to examine the factor structure of the BSCS among a cohort of adolescents, particularly from the United States. This study tested the factor structure of the BSCS among a sample of urban youth of color (N = 383) using SPSS AMOS, a structural equation modeling software. After testing the factor structure, we examined the relationships between each of the BSCS subscales and conceptually related variables (e.g., psychological empowerment, relational power, and school importance). Results from this study confirm the first‐ and second‐order factor structure of the BSCS among youth. BSCS and its underlying subscales were both correlated with one another and correlated with the intrapersonal component of psychological empowerment, relational power, and school importance. Our findings have critical implications for the field of community psychology and the development and use of the BSCS among adolescents.
Elevated transforming growth factor β signaling activation in β‐actin‐knockout mouse embryonic fibroblasts enhances myofibroblast features
Authors: Xie Xin , Percipalle Piergiorgio 
Published: May 2018

Signaling by the transforming growth factor‐β (TGF‐β) is an essential pathway regulating a variety of cellular events. TGF‐β is produced as a latent protein complex and is required to be activated before activating the receptor. The mechanical force at the cell surface is believed to be a mechanism for latent TGF‐β activation. Using β‐actin null mouse embryonic fibroblasts as a model, in which actin cytoskeleton and cell‐surface biophysical features are dramatically altered, we reveal increased TGF‐β1 activation and the upregulation of TGF‐β target genes. In β‐actin null cells, we show evidence that the enhanced TGF‐β signaling relies on the active utilization of latent TGF‐β1 in the cell culture medium. TGF‐β signaling activation contributes to the elevated reactive oxygen species production, which is likely mediated by the upregulation of Nox4. The previously observed myofibroblast phenotype of β‐actin null cells is inhibited by TGF‐β signaling inhibition, while the expression of actin cytoskeleton genes and angiogenic phenotype are not affected. Together, our study shows a scenario that the alteration of the actin cytoskeleton and the consequent changes in cellular biophysical features lead to changes in cell signaling process such as TGF‐β activation, which in turn contributes to the enhanced myofibroblast phenotype.
Modeling and simulation of DC and microwave characteristics of AlInN(AlGaN)/AlN/GaN MOSHEMTs with different gate lengths
Authors: Amarnath G. , Panda D.K. , Lenka T.R. 
Published: May 2018

AbstractIn this paper, direct current (DC) and microwave characteristics are modeled and analyzed for AlInN(AlGaN)/AlN/GaN metal‐oxide‐semiconductor high electron mobility transistors with different gate lengths. The 2‐dimensional electron gas sheet charge density (ns) model is developed by considering polarization effect and flat‐band voltage with lowest occupied energy level (E0) in the quantum well. The drain current, transconductance, and gate charge model is developed by incorporating approximation of ns as proposed in this paper. Then, the cut‐off frequency is calculated from the transconductance and gate capacitance model. The analytical model results are in good agreement with Technology Computer Aided Design simulation and experimental results from literatures for DC and microwave characteristics for the proposed gate lengths (0.1, 0.2, and 0.3 μm). From these characteristics, it is also observed that AlInN/AlN/GaN MOSHEMT shows superior DC and radio frequency performance as compared with AlGaN/AlN/GaN MOSHEMT. AlInN/AlN/GaN MOSHEMT produces high drain current (2.34 A/mm) and high cut‐off frequency (124 GHz) at smaller gate length.