bluuebunny/crossref_metadata_2025 huggingface dataset:
A long‐term perspective on microclimate and spring plant phenology in the Western Cascades
Authors: Ward Sarah E. , Schulze Mark , Roy Bitty
Published: October 2018

Phenology—recurring seasonal events in an organism's life cycle—is largely driven by local climates <1 km2 (microclimates), and changes in phenology are frequently used to indicate a species’ or community response to climate change. Phenological shifts can result in trophic asynchrony, population declines of higher‐level consumers, and reduction of plant fitness. While timing of phenological events is often correlated with elevation, studies have shown that microclimates created by areas of heterogeneous topography can be decoupled from regional climate patterns and that the distribution of microclimates does not always follow the elevation gradient. To examine the interaction between regional weather patterns and microclimate, and the subsequent effect of microclimate on phenology, we conducted standardized weekly spring phenology surveys of 18 native forest plants at the H.J. Andrews Experimental Forest in the Western Cascades from 2009 to 2016. We saw a high degree of inter‐annual variability of microclimate within and across sites, resulting in a changing pattern of microclimate diversity across the landscape from year to year. Most importantly, we saw that years with regional conditions predicted by continued climate change showed a loss of diversity in both microclimate and phenological events, with a more rapid advancement in bud break occurring at higher elevation sites. This study highlights the importance of understanding the interactions between regional and local processes that determine microclimate conditions and how those conditions influence patterns of plant phenology within forest communities, across mountain landscapes and over time, with implications for the capacity of mountainous regions to buffer local communities against the effects of climate change.
Site conditions are more important than abundance for explaining plant invasion impacts on soil nitrogen cycling
Authors: Lee Marissa R. , Flory S. Luke , Phillips Richard P. , Wright Justin P.
Published: October 2018

Invasive plant species can alter critical ecosystem processes including nitrogen transformations, but it is often difficult to anticipate where in an invaded landscape, these effects will occur. Our predictive ability lags because we lack a framework for understanding the multiple pathways through which environmental conditions mediate invader impacts. Here, we present a framework using structural equation modeling to evaluate the impact of an invasive grass, Microstegium vimineum (M.v.), on nitrogen cycling based on a series of invaded sites that varied in invader biomass and non‐M.v. understory biomass, tree basal area, light availability, and soil conditions. Unlike previous studies, we did not find an overall pattern of elevated nitrate concentrations or higher nitrification rates in M.v.‐invaded areas. We found that reference plot conditions mediated differences in mineralization between paired invaded and reference plots at each site through indirect (via M.v. biomass), direct, and interactive pathways; however, the strongest pathways were independent of M.v. biomass. For example, sites with low reference soil nitrate and high non‐M.v. understory biomass tended to have faster mineralization at 5–15 cm in invaded plots. These findings suggest that more attention to reference conditions is needed to understand the impact of invasive species on soil nitrogen cycling and other ecosystem processes and that the greatest impacts will not necessarily be where the invader is most abundant.
Unfolding long‐term Late Pleistocene–Holocene disturbances of forest communities in the southwestern Amazonian lowlands
Authors: Rossetti Dilce F. , Gribel Rogério , Toledo Peter M. , Tatumi Sonia H. , Yee Márcio , Tudela Diego R. G. , Munita Casimiro S. , de Souza Coelho Luiz
Published: October 2018

Linking the distribution of plant species to geology has generally been biased by the over‐simplification of landscape evolution and the lack of understanding of complex geological processes. The Amazonian lowlands have forests in different successional stages, and a growing perception is that such heterogeneity results from long‐term environmental changes. This hypothesis is investigated by designing an analytical model based on past and present‐day vegetation and successions of the plant communities, combined with an advanced understanding of geological history. An area of southwestern Amazonia was selected for floristic inventories, and we interpreted the paleovegetation based on C/N and δ13C analyses of sedimentary organic matter. These data were examined in the context of the geological evolution on the basis of new sedimentological and chronological data. The topographically high Late Pleistocene deposits had continuous and highly diversified late‐successional terra firme forests as well as local fluvial paleolandforms of younger ages with less diversified campinarana forests. Late Pleistocene–Holocene terrains in intermediate elevations had terra firme forests, but shorter trees with lower basal areas and ecotonal forests appeared near the confines of the forest–savanna, while Holocene deposits recorded only seasonally flooded varzea forests. Several deposits of Late Pleistocene and Late Pleistocene–Holocene age recorded an expansion of C4 terrestrial plants before the establishment of the forest from ~20,000 cal yr BP to 7578 cal yr BP, which is not related to past arid episodes. We recorded forests with onsets at 6130–3533 cal yr BP, 3402–2800 cal yr BP, and 1624–964 cal yr BP to terra firme, varzea, and ecotonal forests, respectively. However, not all forests have reached maturity stages due to their location on terrains with a diverse history of terrace downcutting and deposition, which had a direct impact on local hydrology with the interaction of topographic gradients. The hydrology of the study area was also controlled by the distance from the main river valley. Capturing long‐term disturbances over this region of still pristine forests may help elucidate the potential mechanisms that also determine trends in tree growth and forest diversity in other Neotropical regions.
Legitimate visitors and nectar robbers of Aquilegia formosa have different effects on nectar bacterial communities
Authors: Zemenick Ash T. , Rosenheim Jay A. , Vannette Rachel L.
Published: October 2018

Metacommunity structure is strongly influenced by dispersal between habitat patches. Dispersal mode (e.g., active or passively via vector, wind, or water) is recognized to influence metacommunity dynamics, but it is not well understood how within‐mode heterogeneity impacts dispersal and community assembly, particularly for microbial communities. Microbes often rely on flower visitors for dispersal among short‐lived floral nectar habitats, but it is unclear whether flower visitor guilds (e.g., legitimate visitors vs. larcenists) differentially influence nectar microbial diversity and community structure. We surveyed the community of legitimate nectar foragers and nectar robbers, which damage flowers to obtain floral rewards, of Aquilegia formosa. Then, we evaluated how manipulating access by legitimate nectar foragers, primary nectar robbers, and/or secondary nectar robbers influenced the diversity, species composition, and beta diversity of nectar bacteria within individual flowers. A taxonomically diverse insect community visited A. formosa, and visitors differentially influenced nectar bacterial community structure at within‐flower (local) and among‐flower (regional) scales. When legitimate nectar foragers were allowed to access A. formosa, we observed an increase in bacterial diversity and changes in bacterial species composition such that common nectar bacteria had higher relative abundances. In contrast, effects of natural and simulated robbing had little effect on bacterial alpha diversity, but simulated robbing decreased the relative abundance of common nectar bacteria, and natural nectar robbing events reduced beta diversity of nectar bacteria. This work highlights the importance of visitor identity on microbial diversity and species composition in flowers, and, more broadly, suggests that vectors can differentially influence metacommunity structure.
NDVI exhibits mixed success in predicting spatiotemporal variation in caribou summer forage quality and quantity
Authors: Johnson Heather E. , Gustine David D. , Golden Trevor S. , Adams Layne G. , Parrett Lincoln S. , Lenart Elizabeth A. , Barboza Perry S.
Published: October 2018

The satellite‐derived Normalized Difference Vegetation Index (NDVI) is commonly used by researchers and managers to represent ungulate forage conditions in landscapes across the globe, despite limited information about how it compares to empirical measurements of forage quality and quantity. The application of NDVI as a forage metric is particularly appealing for studying migratory caribou (Rangifer tarandus) in remote Arctic ecosystems, where field assessments are logistically and financially prohibitive, and climate‐mediated changes in vegetation have been hypothesized to influence population declines. To determine the utility of NDVI for adequately representing caribou forage conditions, we compared NDVI derived from Moderate Resolution Imaging Spectroradiometer (MODIS) satellite imagery to empirical measures of caribou forage biomass, nitrogen, digestible nitrogen, and digestible energy within the summer range of the Central Arctic Caribou Herd on the North Slope of Alaska. Specifically, we determined the strength of forage–NDVI relationships at the start of the growing season and across the summer, assessed the efficacy of NDVI variables for modeling spatiotemporal variation in field measurements of different forage components, and used long‐term MODIS data to estimate temporal changes in forage between 2000 and 2016. We found that NDVI values were weakly correlated with caribou forage quality at the start of the growing season and throughout the summer. Although linear models of forage–NDVI relationships performed poorly, NDVI variables (NDVI and the number of days from when NDVI reached its maximum value) were useful for modeling spatiotemporal variation in empirical measurements of forage components across the growing season, but only when we incorporated nonlinear forage–NDVI relationships and other habitat covariates. Phenological advances in the date of peak NDVI were associated with significant changes in forage conditions, particularly nitrogen, which exhibited earlier seasonal declines. Using long‐term MODIS data, predicted values of forage nitrogen declined between 2000 and 2016, driven by exceedingly low values in 2014 and 2015. Given our results, we caution the application of NDVI as a general (linear) proxy of caribou forage conditions across the growing season, and encourage practitioners to use NDVI variables to model spatiotemporal variation in specific forage conditions from empirical field data, accounting for nonlinear forage–NDVI relationships.
Mixed effects of an introduced ecosystem engineer on the foraging behavior and habitat selection of predators
Authors: Haram Linsey E. , Kinney Kaitlin A. , Sotka Erik E. , Byers James E.
Published: October 2018

Invasive ecosystem engineers both positively and negatively affect their recipient ecosystems by generating novel habitats. Many studies have focused on alterations to ecosystem properties and to native species diversity and abundance caused by invasive engineers. However, relatively few studies have documented the extent to which behaviors of native species are affected. The red seaweedGracilaria vermiculophylla(Rhodophyta) invaded estuaries of the southeastern United States within the last few decades and now provides abundant aboveground vegetative cover on intertidal mudflats that were historically devoid of seaweeds. We hypothesized thatG. vermiculophyllawould affect the foraging behavior of native shorebirds positively for birds that target seaweed‐associated invertebrates or negatively for birds that target prey on or within the sediment now covered with seaweed. Visual surveys of mudflats >1 ha in size revealed that more shorebirds occurred on mudflats withG. vermiculophyllarelative to mudflats withoutG. vermiculophylla. This increased density was consistent across 7 of 8 species, with the one exception being the semipalmated ploverCharadrius semipalmatus. A regression‐based analysis indicated that while algal presence predicted shorebird density, densities of some bird species depended on sediment composition and infaunal invertebrate densities. At smaller spatial scales (200 m2and <1 m2), experimental removals and additions ofG. vermiculophyllaand focal observations showed strong variation in behavioral response toG. vermiculophyllaamong bird species. Birds preferentially foraged in bare mud (e.g.,C. semipalmatus), inG. vermiculophylla(e.g.,Arenaria interpres), or displayed no preference for either habitat (e.g.,Tringa semipalmata). Thus, while the presence of the invasive ecosystem engineer on a mudflat appeared to attract greater numbers of these predators, shorebird species differed in their behavioral responses at the smaller spatial scales that affect their foraging. Our research illuminates the need to account for species identity, individual behavior, and scale when predicting the impacts of invasive species on native communities.
Density‐dependence mediates coral assemblage structure
Authors: Edmunds Peter J. , Nelson Hannah R. , Bramanti Lorenzo
Published: October 2018

Density dependence (DD) controls community recovery following widespread mortality, yet this principle rarely has been applied to coral assemblages. The reefs of Mo'orea, French Polynesia, provide the opportunity to study DD of coral population growth, because coral assemblages in this location responded to declines in abundance with high recruitment and an increase in cover during which recruitment of pocilloporid corals was inversely associated with density. This study tests for DD in this system, first, by describing the context within which it operates: coral cover changed from 46% in 2005, to <1% in 2010 following an outbreak of a corallivorous sea star and a cyclone, and then increased to 74% by 2017, in large part through inverse density‐associated pocilloporid recruitment. Second, a test for DD of recruitment was conducted by decreasing Pocillopora spp. cover from 33% to 19%: one year later, the density of Pocillopora spp. recruits was 1.65‐fold higher in the low vs. high cover treatment. Finally, the effects of DD were investigated by comparing simulated and empirical distributions of pocilloporid colonies: as predicted by DD, small colonies were randomly distributed, while large colonies were uniformly distributed. Together these results demonstrate DD of population regulation for Pocillopora spp. corals, thus revealing the potential importance of this ecological principle in determining the resilience of coral assemblages.
Foliar fungal endophyte communities are structured by environment but not host ecotype in Panicum virgatum (switchgrass)
Authors: Whitaker Briana K. , Reynolds Heather L. , Clay Keith
Published: October 2018

Experimental tests of community assembly mechanisms for host‐associated microbiomes in nature are lacking. Asymptomatic foliar fungal endophytes are a major component of the plant microbiome and are increasingly recognized for their impacts on plant performance, including pathogen defense, hormonal manipulation, and drought tolerance. However, it remains unclear whether fungal endophytes preferentially colonize certain host ecotypes or genotypes, reflecting some degree of biotic adaptation in the symbioses, or whether colonization is simply a function of spore type and abundance within the local environment. Whether host ecotype, local environment, or some combination of both controls the pattern of microbiome formation across hosts represents a new dimension to the age‐old debate of nature versus nurture. Here, we used a reciprocal transplant design to explore the extent of host specificity and biotic adaptation in the plant microbiome, as evidenced by differential colonization of host genetic types by endophytes. Specifically, replicate plants from three locally‐adapted ecotypes of the native grass Panicum virgatum (switchgrass) were transplanted at three geographically distinct field sites (one home and two away) in the Midwestern US. At the end of the growing season, plant leaves were harvested and the fungal microbiome characterized using culture‐dependent sequencing techniques. Our results demonstrated that fungal endophyte community structure was determined by local environment (i.e., site), but not by host ecotype. Fungal richness and diversity also strongly differed by site, with lower fungal diversity at a riparian field site, whereas host ecotype had no effect. By contrast, there were significant differences in plant phenotypes across all ecotypes and sites, indicating ecotypic differentiation of host phenotype. Overall, our results indicate that environmental factors are the primary drivers of community structure in the switchgrass fungal microbiome.
Double‐structured sparse multitask regression with application of statistical downscaling
Authors: Li Yi , Ding A. Adam
Published: October 2018

Statistical learning of high‐dimensional data often improves learning performance by taking advantage of structural information hidden in data. In this paper, we investigate the structured multitask learning problem and propose a generalized estimator to utilize the structural information simultaneously from the predictors and from the response variables. The key idea of our methodology is to apply flexible quadratic penalties to regularize the likelihood function that incorporates both types of structural information. We prove the theoretical statistical properties of the proposed estimator, which generalizes several state‐of‐the‐art sparse learning methods. Numerical examples are provided for the proposed estimator on synthetic data and on the statistical downscaling problem in climate research.
Unsupervised space–time clustering using persistent homology
Authors: Islambekov Umar , Gel Yulia R.
Published: October 2018

This paper presents a new clustering algorithm for space–time data based on the concepts of topological data analysis and, in particular, persistent homology. Employing persistent homology—a flexible mathematical tool from algebraic topology used to extract topological information from data—in unsupervised learning is an uncommon and novel approach. A notable aspect of this methodology consists in analyzing data at multiple resolutions, which allows for distinguishing true features from noise based on the extent of their persistence. We evaluate the performance of our algorithm on synthetic data and compare it to other well‐known clustering algorithms such as K‐means, hierarchical clustering, and DBSCAN (density‐based spatial clustering of applications with noise). We illustrate its application in the context of a case study of water quality in the Chesapeake Bay.
A study of links between the Arctic and the midlatitude jet stream using Granger and Pearl causality
Authors: Samarasinghe S. M. , McGraw M. C. , Barnes E. A. , Ebert‐Uphoff I.
Published: October 2018

This paper investigates causal links between Arctic temperatures and the jet streams. We apply two different frameworks for this application based on the concepts of (1) Granger causality and (2) Pearl causality. Both methods show that Arctic temperature and jet speed and position all exhibit strong autocorrelation, but they also show that these variables are linked together by two robust positive feedback loops that operate on time scales of 5–25 days. The dynamical implications of these feedbacks are discussed. This study is only the beginning of a larger effort to apply and compare different causality methods in order to gain a deeper understanding of the causal connections between the Arctic and weather at lower latitudes.
Brief history of anti‐seizure drug development
Authors: Rho Jong M. , White H. Steve
Published: October 2018

The mainstay of therapy for epilepsy is anti‐seizure drugs (ASDs, also referred to as anticonvulsants and anti‐epileptic medications). Through much of the past century, only a handful for ASDs were available for clinical use. However, with the creation of the U.S. National Institutes of Health/National Institute of Neurological Disorders and Stroke (NINDS)–sponsored Anticonvulsant Screening Program (ASP), coupled with the emergence of high‐throughput screening platforms and methodologies, and advances in our understanding of the fundamental neurobiology of epilepsy, ASD development has greatly accelerated over the past 25 years. More than 18 new ASDs have been approved for clinical use since the inception of the ASP. Despite this remarkable success and the emergence of drugs possessing more favorable pharmacokinetic profiles that act on novel molecular targets, there has been increasing recognition that the paradigms for drug discovery have not yielded significant improvements in therapeutic efficacy, and that disease modification (i.e., anti‐epileptogenesis), among other challenges, must be addressed. Thus, with the renewed framework and mission of improving the lives of people with epilepsy, the name of the ASP was changed to the Epilepsy Therapy Screening Program (ETSP). This review briefly summarizes the history of ASD development and outlines some of the challenges and opportunities for the next generation of drug therapies for the epilepsy field.
Probabilistic seismic demand assessment accounting for finite element model class uncertainty: Application to a code‐designed URM infilled reinforced concrete frame building
Authors: Alam Mohammad S. , Barbosa Andre R.
Published: October 2018

Reliable and robust probabilistic assessment of structures requires explicit consideration of all relevant sources of uncertainty, both aleatory and epistemic. This paper proposes a formulation to incorporate model class uncertainty in probabilistic seismic demand assessment (PSDA) of structures, where model class uncertainty relates to the use of different structural analysis models used to predict the physical response of structural systems. The application of the proposed formulation is illustrated through the assessment of a recent code‐designed reinforced concrete (RC) frame building with unreinforced masonry (URM) infills, which is a prevalent form of construction worldwide. The model class uncertainty analyzed in this paper is related to the potential selection of one of three state‐of‐the‐art masonry infill strut models. In the application example, nonlinear static pushover (NSP) analyses and tornado sensitivity analyses are performed to identify the important parameters of infill strut models affecting the seismic response of the infilled RC frame. A hybrid stripe analysis (HSA) approach is adopted to perform nonlinear response history analyses (NRHAs) of the example RC frame. To account for relevant sources of uncertainty, latin hypercube sampling (LHS) is used to quantify the minimum number of realizations of model parameters necessary to achieve convergence of the coefficient of variation (COV) of the engineering response parameters assessed. Results of the NRHAs indicate that incorporating model class uncertainty significantly affects the estimation of uncertainties of the drift hazard demand.
Living in poisoning environments: Invisible risks and human adaptation
Authors: Arriaza Bernardo , Amarasiriwardena Dulasiri , Standen Vivien , Yáñez Jorge , Van Hoesen John , Figueroa Leonardo
Published: October 2018

This article describes the hidden natural chemical contaminants present in a unique desert environment and their health consequences on ancient populations. Currently, millions of people are affected worldwide by toxic elements such as arsenic. Using data gathered from Atacama Desert mummies, we discuss long‐term exposure and biocultural adaptation to toxic elements. The rivers that bring life to the Atacama Desert are paradoxically laden with arsenic and other minerals that are invisible and tasteless. High intake of these toxic elements results in severe health and behavioral problems, and even death. We demonstrate that Inca colonies, from Camarones 9 site, were significantly affected by chemical contaminants in their food and water. It appears however, some modern‐day Andean populations resist the elevated levels of arsenic exposure as a result of positive selection mediated via the arsenic methyltransferase enzyme and display more tolerance to high chemical doses. This article further debate the effects of natural pollution and biocultural adaptation of past populations.
A Comparative Study on Rapid Wastewater Treatment Response to Refugee Crises
Authors: Kosonen Heta , Kim Amy , Gough Heidi , Mikola Anna , Vahala Riku
Published: October 2018

Large‐scale population displacement can overwhelm wastewater treatment facilities and increase environmental pollution in the host communities. Academic research has discussed features that improve wastewater treatment systems' resiliency toward other types of disasters and rapidly changing operation conditions. Concepts that contribute to successful startup, refurbishment, and operation of biological treatment systems during refugee responses are yet to be identified. This study takes a novel approach to analyzing wastewater treatment system resiliency by presenting an input–mediator–output model analysis on advanced wastewater treatment delivery during refugee response in Jordan and Finland in 2015–2016. By comparing two distinctively different case studies, the research identifies principles that contribute to timely refugee response in advanced wastewater treatment systems on the dimensions of human resources, project environment, and wastewater treatment technology. These principles include 1) clear role division between agencies and stakeholders, 2) improving “human capacity” for rapid response decisions, 3) selecting a process that fits the regulative and operational environment, 4) enabling direct and fast information sharing, and 5) establishing fast‐track permitting processes for disaster conditions. Wastewater treatment system operators, regulative authorities, and aid organizations can use these findings to support rapid decision‐making in future disaster response situations.
Generalizing polygenic risk scores from Europeans to Hispanics/Latinos
Authors: Grinde Kelsey E. , Qi Qibin , Thornton Timothy A. , Liu Simin , Shadyab Aladdin H. , Chan Kei Hang K. , Reiner Alexander P. , Sofer Tamar
Published: October 2018

Polygenic risk scores (PRSs) are weighted sums of risk allele counts of single‐nucleotide polymorphisms (SNPs) associated with a disease or trait. PRSs are typically constructed based on published results from Genome‐Wide Association Studies (GWASs), and the majority of which has been performed in large populations of European ancestry (EA) individuals. Although many genotype‐trait associations have generalized across populations, the optimal choice of SNPs and weights for PRSs may differ between populations due to different linkage disequilibrium (LD) and allele frequency patterns. We compare various approaches for PRS construction, using GWAS results from both large EA studies and a smaller study in Hispanics/Latinos: The Hispanic Community Health Study/Study of Latinos (HCHS/SOL, ). We consider multiple approaches for selecting SNPs and for computing SNP weights. We study the performance of the resulting PRSs in an independent study of Hispanics/Latinos from the Women’s Health Initiative (WHI, ). We support our investigation with simulation studies of potential genetic architectures in a single locus. We observed that selecting variants based on EA GWASs generally performs well, except for blood pressure trait. However, the use of EA GWASs for weight estimation was suboptimal. Using non‐EA GWAS results to estimate weights improved results.
Structural covariance across the lifespan: Brain development and aging through the lens of inter‐network relationships
Authors: Aboud Katherine S. , Huo Yuankai , Kang Hakmook , Ealey Ashley , Resnick Susan M. , Landman Bennett A. , Cutting Laurie E.
Published: October 2018

Recent studies have revealed that brain development is marked by morphological synchronization across brain regions. Regions with shared growth trajectories form structural covariance networks (SCNs) that not only map onto functionally identified cognitive systems, but also correlate with a range of cognitive abilities across the lifespan. Despite advances in within‐network covariance examinations, few studies have examined lifetime patterns of structural relationships across known SCNs. In the current study, we used a big‐data framework and a novel application of covariate‐adjusted restricted cubic spline regression to identify volumetric network trajectories and covariance patterns across 13 networks (n = 5,019, ages = 7–90). Our findings revealed that typical development and aging are marked by significant shifts in the degree that networks preferentially coordinate with one another (i.e., modularity). Specifically, childhood showed higher modularity of networks compared to adolescence, reflecting a shift over development from segregation to desegregation of inter‐network relationships. The shift from young to middle adulthood was marked by a significant decrease in inter‐network modularity and organization, which continued into older adulthood, potentially reflecting changes in brain organizational efficiency with age. This study is the first to characterize brain development and aging in terms of inter‐network structural covariance across the lifespan.
Data‐driven approaches for tau‐PET imaging biomarkers in Alzheimer's disease
Authors: Vogel Jacob W. , Mattsson Niklas , Iturria‐Medina Yasser , Strandberg Olof T. , Schöll Michael , Dansereau Christian , Villeneuve Sylvia , van der Flier Wiesje M. , Scheltens Philip , Bellec Pierre , Evans Alan C. , Hansson Oskar , Ossenkoppele Rik ,   The Alzheimer's Disease Neuroimaging Initiative,   The Swedish BioFINDER Study
Published: October 2018

Previous positron emission tomography (PET) studies have quantified filamentous tau pathology using regions‐of‐interest (ROIs) based on observations of the topographical distribution of neurofibrillary tangles in post‐mortem tissue. However, such approaches may not take full advantage of information contained in neuroimaging data. The present study employs an unsupervised data‐driven method to identify spatial patterns of tau‐PET distribution, and to compare these patterns to previously published “pathology‐driven” ROIs. Tau‐PET patterns were identified from a discovery sample comprised of 123 normal controls and patients with mild cognitive impairment or Alzheimer's disease (AD) dementia from the Swedish BioFINDER cohort, who underwent [18F]AV1451 PET scanning. Associations with cognition were tested in a separate sample of 90 individuals from ADNI. BioFINDER [18F]AV1451 images were entered into a robust voxelwise stable clustering algorithm, which resulted in five clusters. Mean [18F]AV1451 uptake in the data‐driven clusters, and in 35 previously published pathology‐driven ROIs, was extracted from ADNI [18F]AV1451 scans. We performed linear models comparing [18F]AV1451 signal across all 40 ROIs to tests of global cognition and episodic memory, adjusting for age, sex, and education. Two data‐driven ROIs consistently demonstrated the strongest or near‐strongest effect sizes across all cognitive tests. Inputting all regions plus demographics into a feature selection routine resulted in selection of two ROIs (one data‐driven, one pathology‐driven) and education, which together explained 28% of the variance of a global cognitive composite score. Our findings suggest that [18F]AV1451‐PET data naturally clusters into spatial patterns that are biologically meaningful and that may offer advantages as clinical tools.
tDCS modulates behavioral performance and the neural oscillatory dynamics serving visual selective attention
Authors: McDermott Timothy J. , Wiesman Alex I. , Mills Mackenzie S. , Spooner Rachel K. , Coolidge Nathan M. , Proskovec Amy L. , Heinrichs‐Graham Elizabeth , Wilson Tony W.
Published: October 2018

Transcranial direct‐current stimulation (tDCS) is a noninvasive method for modulating human brain activity. Although there are several hypotheses about the net effects of tDCS on brain function, the field's understanding remains incomplete and this is especially true for neural oscillatory activity during cognitive task performance. In this study, we examined whether different polarities of occipital tDCS differentially alter flanker task performance and the underlying neural dynamics. To this end, 48 healthy adults underwent 20 min of anodal, cathodal, or sham occipital tDCS, and then completed a visual flanker task during high‐density magnetoencephalography (MEG). The resulting oscillatory responses were imaged in the time‐frequency domain using beamforming, and the effects of tDCS on task‐related oscillations and spontaneous neural activity were assessed. The results indicated that anodal tDCS of the occipital cortices inhibited flanker task performance as measured by reaction time, elevated spontaneous activity in the theta (4–7 Hz) and alpha (9–14 Hz) bands in prefrontal and occipital cortices, respectively, and reduced task‐related theta oscillatory activity in prefrontal cortices during task performance. Cathodal tDCS of the occipital cortices did not significantly affect behavior or any of these neuronal parameters in any brain region. Lastly, the power of theta oscillations in the prefrontal cortices was inversely correlated with reaction time. In conclusion, anodal tDCS modulated task‐related oscillations and spontaneous activity across multiple cortical areas, both near the electrode and in distant sites that were putatively connected to the targeted regions.
The impact of type 1 diabetes on neural activity serving attention
Authors: Embury Christine M. , Wiesman Alex I. , McDermott Timothy J. , Proskovec Amy L. , Heinrichs‐Graham Elizabeth , Lord Grace H. , Brau Kaitlin L. , Drincic Andjela T. , Desouza Cyrus V. , Wilson Tony W.
Published: October 2018

Type 1 diabetes has been associated with alterations in attentional processing and other cognitive functions, and previous studies have found alterations in both brain structure and function in affected patients. However, these previous neuroimaging studies have generally examined older patients, particularly those with major comorbidities known to affect functioning independent of diabetes. The primary aim of the current study was to examine the neural dynamics of selective attention processing in a young group of patients with type 1 diabetes who were otherwise healthy (i.e., without major comorbidities). Our hypothesis was that these patients would exhibit significant aberrations in attention circuitry relative to closely matched controls. The final sample included 69 participants age 19–35 years old, 35 with type 1 diabetes and 34 matched nondiabetic controls, who completed an Eriksen flanker task while undergoing magnetoencephalography. Significant group differences in flanker interference activity were found across a network of brain regions, including the anterior cingulate, inferior parietal cortices, paracentral lobule, and the left precentral gyrus. In addition, neural activity in the anterior cingulate and the paracentral lobule was correlated with disease duration in patients with type 1 diabetes. These findings suggest that alterations in the neural circuitry underlying selective attention emerge early in the disease process and are specifically related to type 1 diabetes and not common comorbidities. These findings highlight the need for longitudinal studies in large cohorts to clarify the clinical implications of type 1 diabetes on cognition and the brain.
Opposing patterns of neuronal variability in the sensorimotor network mediate cyclothymic and depressive temperaments
Authors: Conio Benedetta , Magioncalda Paola , Martino Matteo , Tumati Shankar , Capobianco Laura , Escelsior Andrea , Adavastro Giulia , Russo Daniel , Amore Mario , Inglese Matilde , Northoff Georg
Published: October 2018

Affective temperaments have been described since the early 20th century and may play a central role in psychiatric illnesses, such as bipolar disorder (BD). However, the neuronal basis of temperament is still unclear. We investigated the relationship of temperament with neuronal variability in the resting state signal—measured by fractional standard deviation (fSD) of Blood‐Oxygen‐Level Dependent signal—of the different large‐scale networks, that is, sensorimotor network (SMN), along with default‐mode, salience and central executive networks, in standard frequency band (SFB) and its sub‐frequencies slow4 and slow5, in a large sample of healthy subject (HC, n = 109), as well as in the various temperamental subgroups (i.e., cyclothymic, hyperthymic, depressive, and irritable). A replication study on an independent dataset of 121 HC was then performed. SMN fSD positively correlated with cyclothymic z‐score and was significantly increased in the cyclothymic temperament compared to the depressive temperament subgroups, in both SFB and slow4. We replicated our findings in the independent dataset. A relationship between cyclothymic temperament and neuronal variability, an index of intrinsic neuronal activity, in the SMN was found. Cyclothymic and depressive temperaments were associated with opposite changes in the SMN variability, resembling changes previously described in manic and depressive phases of BD. These findings shed a novel light on the neural basis of affective temperament and also carry important implications for the understanding of a potential dimensional continuum between affective temperaments and BD, on both psychological and neuronal levels.
Tri(1‐naphthyl)phosphine as a ligand in palladium‐free Sonogashira cross‐coupling of arylhalogenides with acetylenes
Authors: Govdi Anastasiya I. , Vasilevsky Sergey F. , Malysheva Svetlana F. , Kazheva Olga N. , Dyachenko Oleg A. , Kuimov Vladimir A.
Published: October 2018

Tri(1‐naphthyl)phosphine (Np3P) has been easily prepared in 34% yield from red phosphorus and 1‐bromonaphthalene in the superbasic system t‐BuONa/DMSO. The expedient procedures for the synthesis of aryl acetylenes by Sonogashira coupling of aryl iodides with terminal alkynes using Np3P as a ligand have been developed. For the first time, it is found that the reaction with compounds containing electron‐donating substituents preferably affords buta‐1,3‐diynes.
Promotion of healthy eating in clubs with junior teams in Australia: A cross‐sectional study of club representatives and parents
Authors: Gonzalez Sharleen , Clinton‐McHarg Tara , Kingsland Melanie , Hall Alix , Lecathelinais Christophe , Milner Sharin , Sherker Shauna , Rogers Ben , Doran Christopher , Brooke Daisy , Wiggers John , Wolfenden Luke
Published: October 2018

Issues addressed

To: (i) describe the prevalence of policies and practices promoting healthy eating implemented by sports clubs with junior teams; (ii) examine differences in such practices across geographic and operational characteristics of clubs; and (iii) describe the attitudes of club representatives and parents regarding the acceptability of sports clubs implementing policies and practices to promote healthy eating.

Methods

Cross‐sectional telephone surveys of junior community football club management representatives and parents/carers of junior players were conducted in the states of New South Wales and Victoria, Australia in 2016.

Results

Seventy‐nine of the 89 club representatives approached to participate completed the telephone survey. All clubs (100%; 95% CI 96.2‐100.0) reported recommending fruit or water be provided to players after games or at half‐time, 24% (95% CI 14.4‐33.7) reported promoting healthy food options through prominent positioning at point of sale and only 8% (95% CI 1.6‐13.6) of clubs had a written healthy eating policy. There were no significant differences between the mean number of healthy eating policies and practices implemented by club socio‐economic or geographic characteristics. Club representatives and parents/carers were supportive of clubs promoting healthy eating for junior players.

Conclusions

While there is strong support within sporting clubs with junior teams for policies and practices to promote healthy eating, their implementation is highly variable.

So what?

A considerable opportunity remains for health promotion policy and practice improvement in clubs with junior teams, particularly regarding policies related to nutrition.
Fundamental solution of steady and transient bio heat transfer equations especially for skin burn and hyperthermia treatments
Authors: Deka Kashmiri , Bhanja Dipankar , Nath Sujit
Published: October 2018

In the field of bio heat transfer, as of now, the main concern of researchers lies in the proper and accurate thermal damage of the diseased tissues without destroying or damaging the neighboring healthy tissues during the tumor treatment. The present work aims to develop a new approach toward solving the bio heat transfer equations for the skin burn and hyperthermia treatments. Both analytical and numerical solutions are proposed. For the analytical study, a differential transform method is used to solve steady and unsteady state heat equations. The finite volume method is adopted to solve these equations numerically, which provides a better scope to solve the highly nonlinear complex equations. To obtain a complete solution, a code is developed in MATLAB and MATHEMATICA. The variation of different parameters, such as perfusion constant, space heating, surface step heating, and thermal conductivity, with time were observed. Apart from the above analysis of temperature distribution during skin burn through the spilling of hot beverage, its numerical solution was also performed for this problem at different boundary conditions. It was observed that with the help of the temperature distribution, depending on the time and the severity of the burn, different ranges of depths of the burn can be determined.
Effects of hypnotics on prefrontal cortex activity during a verbal fluency task in healthy male subjects: A near‐infrared spectroscopy study
Authors: Tsuruta Yoshiyuki , Iwamoto Kunihiro , Banno Masahiro , Kawano Naoko , Kohmura Kunihiro , Miyata Seiko , Fujishiro Hiroshige , Noda Yukihiro , Noda Akiko , Iritani Shuji , Ozaki Norio
Published: October 2018

Objective

To assess the effects of hypnotics on prefrontal cortex activity in healthy subjects using near‐infrared spectroscopy (NIRS) in a double‐blind, placebo‐controlled crossover trial.

Methods

Eighteen healthy males received acute doses of ramelteon (8 mg), triazolam (0.125 mg), or placebo in a predetermined randomization schedule, with a washout period of more than 1 week. All subjects performed a verbal fluency task during NIRS assessments at baseline and at 1 and 4 hr post‐dose. The number of words correctly generated during the task (behavioral performance) and scores on the Stanford Sleepiness Scale (SSS) were also recorded at each test time.

Results

Compared with the placebo, triazolam (0.125 mg) significantly decreased oxyhemoglobin (oxy‐Hb) concentration change in NIRS during the posttask period and significantly increased behavioral performance, whereas triazolam (0.125 mg) and ramelteon (8 mg) significantly increased SSS scores.

Conclusions

The differential effects of two types of hypnotics on oxy‐Hb change measured by NIRS were observed in acute dosing, suggesting that when assessing brain activity of patients with psychiatric disorders, researchers should consider how certain types of hypnotics can influence brain function. This would also provide useful information to clinicians when prescribing hypnotics suitable for their patients' conditions.
Supramolecular Chemistry in Solid State Materials such as Metal‐Organic Frameworks
Authors: Fracaroli Alejandro M. , de Rossi Rita H.
Published: October 2018

Supramolecular chemistry has enriched the scientific research for more than fifty years reaching one of its summits in 2016, when the Chemistry Nobel Prize was awarded for the design and synthesis of molecular machines, in which host‐guest chemistry plays a fundamental role. Recently, the groups of Omar Yaghi and Fraser Stoddart, among others, have demonstrated that this chemistry can be extended to the pores of metal‐organic frameworks (MOFs). This heterogenization of supramolecular chemistry can be achieved through the incorporation of macrocycles to the organic struts of these highly porous and crystalline materials. Throughout this short review we summarize interesting examples of selective recognition by naturally occurring and synthetic macrocycles in solution and solid state; and later we survey important milestones to achieve specific recognition sites and develop host‐guest chemistry at the pores of MOFs. This summary contains examples of different synthetic strategies to incorporate macrocycles to solid state materials, and in particular, to prepare supramolecular MOFs with particular properties and related applications. Specifically, the revised research includes the incorporation of both naturally occurring and synthetic macrocycles to solid state materials such as polymers, metal nanoparticles, etc., as prelude of the solid phase recognition studied in MOFs. An important number of the contributions presented here feature porous solids with smooth access to the host's cavity incorporated in the pores, allowing specific recognition of guest molecules. This smooth access to those active recognition sites in materials with extremely high surface area such as MOFs, open the possibility to develop the next generation of frontier materials with application in fields such as selective capture of water toxins and heterogeneous catalysis, among others.
Challenges during diapause and anhydrobiosis: Mitochondrial bioenergetics and desiccation tolerance
Authors: Hand Steven C. , Moore Daniel S. , Patil Yuvraj
Published: October 2018

In preparation for the onset of environmental challenges like overwintering, food limitation, anoxia, or water stress, many invertebrates and certain killifish enter diapause. Diapause is a developmentally‐programed dormancy characterized by suppression of development and metabolism. For embryos of Artemia franciscana (brine shrimp), the metabolic arrest is profound. These gastrula‐stage embryos depress oxidative metabolism by ~99% during diapause and survive years of severe desiccation in a state termed anhydrobiosis. Trehalose is the sole fuel source for this developmental stage. Mitochondrial function during diapause is downregulated primarily by restricting substrate supply, as a result of inhibiting key enzymes of carbohydrate metabolism. Because proton conductance across the inner membrane is not decreased during diapause, the inference is that membrane potential must be compromised. In the absence of any intervention, the possibility exists that the F1Fo ATP synthase and the adenine nucleotide translocator may reverse, leading to wholesale hydrolysis of cellular ATP.

Studies with anhydrobiotes like A. franciscana are revealing multiple traits useful for improving desiccation tolerance that include the expression and accumulation late embryogenesis abundant (LEA) proteins and trehalose. LEA proteins are intrinsically disordered in aqueous solution but gain secondary structure (predominantly α‐helix) as water is removed. These protective agents stabilize biological structures including lipid bilayers and mitochondria during severe water stress. © 2018 IUBMB Life, 70(12):1251–1259, 2018